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  • Calcium  (124)
  • Fine structure
  • Springer  (211)
  • Iranian Fisheries Science Research Institute  (3)
  • American Geophysical Union
  • Irkutsk : Ross. Akad. Nauk, Sibirskoe Otd., Inst. Zemnoj Kory
  • Krefeld : Geologischer Dienst Nordhein-Westfalen
  • Wiley
  • 2015-2019  (3)
  • 2005-2009
  • 1975-1979  (78)
  • 1970-1974  (133)
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  • 1
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    The effect of various concentrations of dietary calcium and phosphorus on biological and culture characteristics of juvenile freshwater Crayfish, Astacus Leptodactylus (2018)
    Iranian Fisheries Science Research Institute | Tehran, Iran
    Details
    Publication Date: 2021-05-19
    Description: This study was performed to investigate the effect of Ca and P on rearing and biological indices of crayfish (Astacus leptodactylus). Twenty-five isonitrogenous and isoenergetic diets were used. The experimental diets were made of the basal diet that was contained casein and gelatin. The basal diet was supplemented with five levels of calcium (0, 1, 2, 3, 4 %)from calcium chloride and five levels of phosphorus (0, 0.5, 1, 1.5, 2%)from natrium phosphate monobasic. The study was conducted in two phases and four experiments. In each experiment the diets with three replicates, totally in the 75 culture tanks containing 100l were used for feeding crayfish with average weights 1-2g and 8-9g for 80 days. In the first and second experiments, 5 and 3 indivisiual crayfish (miniatures) with average weights 1.22±0.21g and 1.31±0.29 g respectively and during the third and forth experiment 10 and 4 indivisiuals crayfish with the average weights 8.48 ±1.03g and 9.06±1.41g respectively were stocked in each cultural tanks. The physicochemical factors of water (temperature, dissolved oxygen, pH as daily and hardness, nitrite, nitrate and phosphate as weekly) were measured for monitoring the condition of farming. The crayfish were fed about 5% of body weight for 3 times per day. The graded levels of Ca did not affect the growth indices. In crayfish (1-2g), weight gain and specific growth rate was significantly affected by the phosphorus levels.The average weight gain, survival, biomass increment in the different treatments was significantly affected by the graded levels of phosphorus. The crayfish were fed with diet containing calcium with 3-4% and phosphorus 1% showed the better growth. In the both group of experimental crayfish, were showed the graded levels of dietary Ca were caused the reduction the body ash and P values were increased. The clear correlation was not observed between the dietary levels of P and body ash and phosphorus in crayfish (1-2g). However, high levels of dietary phosphorus developed the body calcium. In Crayfish (8-9g) showed strong and negatively correlation between the dietary P levels and body ash and calcium. The graded dietary levels of Ca and P were caused increase in molting frequency and weight increment in molting. The optimum dietary levels of Ca and P were analyzed by broken –line regression showed 3-4%, 1% for crayfish 1-2g and 2-3, 1 -1.5% for crayfish 8-9g respectively. The results showed the presence of Ca and P are necessary for normal growth and molting in both group of crayfish. The proper growth was obtained at levels of 2-3% Ca and level of 1% P. Furthermore, the Ca and P ration in diet could not describe the interaction between Ca and P levels on growth function. So the determined Ca and P ratio were not obtained base of growth indices in the freshwater crayfish, Astacus leptodactylus.
    Description: Iranian Fisheries Science Research Institute
    Description: Published
    Keywords: Physicochemical ; Diet ; Calcium ; Phosphorus ; Growth ; Body Composition ; Moulting ; Astacus leptodactylus ; Gelatin ; Crayfish ; Temperature ; Dissolved oxygen ; pH ; Nitrite ; Nitrate ; Juvenile ; Freshwater
    Repository Name: AquaDocs
    Type: Report , Refereed
    Format: 67pp.
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  • 2
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    Determing some important extracted materials, such as : Alginates of sodium & calcium and alginic acid in three species of brown seaweeds (Sargassum illicifolium , Cystoseira indica and Nizimuddinia zanardinii) in coastal erea of Sistan and Baluochestan Provience (2018)
    Iranian Fisheries Science Research Institute | Tehran, Iran
    Details
    Publication Date: 2021-05-19
    Description: This study was determined some important extracted materials, Such as : Alginates of sodium & calcium and alginic acid in three species of brown seaweeds (Sargassum illicifolium , Cystoseira indica and Nizimuddinia zanardinii) during in different season in 1387 in coastal erea of Sistan and Baluochestan Provience. At First seaweeds sample were colected from sea beach and transferd to lab, so washed in fresh water and dried in the sun. So were under Alkaloid extraction with sodium carbonate (5 Persent), that were obtined fluid after filteration. The sodium alginate fibers extracted from fluid were combined by Alcohol. The calacium alginate fibers were deposited by calacium chlorids (5%) and Alginic acid resulted with chloridric acid (1N). The extraction yield of sodium alginate, calacium alginate and alginic acid in different samples of seaweeds with following Explaination: The presentage we have got, can be said , the present average of sodium alginate at Sargassum in Spring season in three areas (Chabahar, Tang and Pasabandar ) Respectively: 28.4±2 , 28.9±2 , 27.2±1.9 present, the present average of sodium alginate at Cystoseira in Spring in three areas at above mentioned goes in this way: 19.7±1.4, 18.6±1.4, 19.2±1.3 present and the present average of sodium alginate at Nizimuddinia in Spring were 23.4±1.5, 23.8±1.5 , 20.6±1.5 in these three areas. The present average of calacium alginate at Sargassum in Spring season in three areas (Chabahar, Tang and Pasabandar ): 33.7±0.5 , 33.7±0.8 , 33.1±1 present, the present average of calacium alginate at Cystoseira in Spring in three areas at above mentioned goes in this way: 28.8±1.5, 27.4±1, 27.4±1.5 present and the present average of calacium alginate at Nizimuddinia in Spring were 35.9±2.8, 23.9±1.5 , 35.9±2.8 in these three areas. The present average of Alginic acid at Sargassum in Spring season in three areas (Chabahar, Tang and Pasabandar ): 19.2±1.6 , 25.6±1.7 , 18.4±1.1 present, the present average of Alginic acid at Cystoseira in Spring in three areas at above mentioned goes in this way: 16.8±1.2, 15.8±1.1, 16.4±1 present and the present average of Alginic acid at Nizimuddinia in Spring were 19.2±1.6, 19.6±1.7 , 18.4±1.5 in these three areas. The present average of sodium alginate at Sargassum in Summer season in three areas (Chabahar, Tang and Pasabandar ) Respectively: 20.8±1 , 21±1 , 27.8±1.9 present, the present average of sodium alginate at Cystoseira in Summer in three areas at above mentioned goes in this way: 21±1.1, 13.2±1, 14.1±0.7 present and the present average of sodium alginate at Nizimuddinia in Summer were 25.3±2.3, 16.7±2.1 , 15.3±1.3 in these three areas. The present average of calacium alginate at Sargassum in Summer season in three areas (Chabahar, Tang and Pasabandar ): 29.5±2.1 , 29.7±2 , 28.3±2.2 present, the present average of calacium alginate at Cystoseira in Summer in three areas at above mentioned goes in this way: 21±1.1, 20.2±0.9, 20±0.7 present and the present average of calacium alginate at Nizimuddinia in Summer were 25.3±2.3, 29.7±2 , 23.1±1.5 in these three areas. The present average of Alginic acid at Sargassum in Summer season in three areas (Chabahar, Tang and Pasabandar ): 19.5±0.7 , 19.7±0.6 , 18.7±0.7 present, the present average of Alginic acid at Cystoseira in Summer in three areas at above mentioned goes in this way: 21±1.1, 11.5±1.4, 11.1±1.5 present and the present average of Alginic acid at Nizimuddinia in Summer were 14.8±1.3, 15.3±1.3 , 14.6±1 in these three areas. The present average of sodium alginate at Sargassum in Autumn season in three areas (Chabahar, Tang and Pasabandar ) Respectively: 31.5±4.3 , 31.6±4.8 , 29.4±4.8 present, the present average of sodium alginate at Cystoseira in Autumn in three areas at above mentioned goes in this way: 23±2.7, 21.4±2.8, 21.4±2.7 present and the present average of sodium alginate at Nizimuddinia in Autumn were 25.8±2.2, 26.4±2.1 , 23.4±1.9 in these three areas. The present average of calacium alginate at Sargassum in Autumn season in three areas (Chabahar, Tang and Pasabandar ): 43.3±1.6 , 42.8±2.7 , 41.7±2.9 present, the present average of calacium alginate at Cystoseira in Autumn in three areas at above mentioned goes in this way: 34.3±5.9, 32.4±5.5, 30.9±5.2 present and the present average of calacium alginate at Nizimuddinia in Autumn were 50±7.1, 50.2±7.5 , 45.6±5.2 in these three areas. The present average of Alginic acid at Sargassum in Autumn season in three areas (Chabahar, Tang and Pasabandar ): 28±3.8 , 28±3.5 , 26±3.9 present, the present average of Alginic acid at Cystoseira in Autumn in three areas at above mentioned goes in this way: 20.2±1.8, 19.2±2.1, 18.7±1.6 present and the present average of Alginic acid at Nizimuddinia in Autumn were 25.9±3, 26.1±2.9 , 24.6±3.6 in these three areas. The present average of sodium alginate at Sargassum in Winter season in three areas (Chabahar, Tang and Pasabandar ) Respectively: 35±1.6, 35.2±1.8 , 33.8±1.9 present, the present average of sodium alginate at Cystoseira in Winter in three areas at above mentioned goes in this way: 24.1±2, 22.9±1.2, 23.3±0.7 present and the present average of sodium alginate at Nizimuddinia in Winter were 28.2±1.3, 29.2±1.7 , 26.2±1.8 in these three areas. The present average of calacium alginate at Sargassum in Winter season in three areas (Chabahar, Tang and Pasabandar ): 45.6±1.9 , 45±2 , 44.6±2.5 present, the present average of calacium alginate at Cystoseira in Winter in three areas at above mentioned goes in this way: 38.2±2.8, 35.9±3.4, 35.6±3.5 present and the present average of calacium alginate at Nizimuddinia in Winter were 56.4±3.5, 56±3.5 , 51.8±2.5 in these three areas. The present average of Alginic acid at Sargassum in winter season in three areas (Chabahar, Tang and Pasabandar ): 31.8±1.2 , 32.1±0.9 , 30.9±1.2 present, the present average of Alginic acid at Cystoseira in Winter in three areas at above mentioned goes in this way: 21.1±1.2, 20.4±1.4, 19.3±1.4 present and the present average of Alginic acid at Nizimuddinia in Winter were 26.4±2.1, 27±2.2 , 24.6±2.2 in these three areas. The more amount of calacium alginate in Autumn can be found at Nizimuddinia in Tang area , wite amount of 50.2 present and the lates amount of Alginic acid at Cystoseira can be found in Summer with 11.1 present. If the Alginic acid become more than 20 present , it can be economical , that it can be showed more than 20 present in Autumn and Winter . According to this results, One way ANOVA showed that average of Alginates were not similar and significant differences ( P〈 0.05 ) between species.
    Description: Iranian Fisheries Science Research Institute
    Description: Published
    Keywords: Economical ; Alginic acid ; Species ; Brown seaweeds ; Sargassum illicifolium ; Cystoseira indica ; Nizimuddinia zanardinii ; Chloridric acid ; ANOVA ; Sodium ; Calcium ; Seaweeds
    Repository Name: AquaDocs
    Type: Report , Refereed
    Format: 74pp.
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  • 3
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    The study of annual cycle of gonads developments and sex steroids of gray mullet, Mugil cephalus in Golestan province (2018)
    Iranian Fisheries Science Research Institute | Tehran, Iran
    Details
    Publication Date: 2021-05-19
    Description: Grey mullet, Mugil cephalus is one of the most famous and valuable fish on the fisheries and aquaculture industry. This species is the most suitable to introducing the southern, northern and central regions of our country due to high resistant to large variation of water salinity and temperature. On the monthly sampling period biometric data including total length and total weight recorded and length and weight classes for every sex were determined. To understanding of physiological functions and sexual development of reproductive organs, this investigation carried out with Grey mullet imported from Hong Kong by 1993. Findings of this research can be used for management of artificial breeding of this species. Daily variation of pond water temperature was recorded. Sex steroid hormones and other plasma metabolites such as Ca2+, cholesterol, triglycerides and total proteins were measured by blood sampling. Gonad samples were prepared in order to histological studies. Oocyte growth was studied by measurement of egg diameters. Measured values of cholesterol, triglycerides of blood plasma revealed that these metabolites have seasonal variation and severely deposited on the summer and mobilized on the spawning seasons. Findings of this research suggested that egg diameters, values of sex steroid hormones (estradiol and progesterone) and Calcium concentrations of fish blood plasma shortening increased a long with day length shortening.
    Description: Iranian Fisheries Science Research Institute
    Description: Published
    Keywords: Physiological ; Mugil cephalus ; Sex steroid hormones ; Plasma metabolites ; Gonads ; Gray mullet ; Mugil cephalus ; Fisheries ; Aquaculture ; Species ; Salinity ; Temperature ; Sampling ; Estradiol ; Progesterone ; Calcium
    Repository Name: AquaDocs
    Type: Report , Refereed
    Format: 53pp.
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  • 4
    Electronic Resource
    Electronic Resource
    Intestinal calcium binding protein in uremia (1979)
    Springer
    Calcified tissue international 27 (1979), S. 205-210 
    Details
    ISSN: 1432-0827
    Keywords: Intestine ; Calcium ; Binding ; Protein ; Uremia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary In order to assess the usefulness of intestinal biopsies as indicators of end-organ responsiveness to vitamin D in uremic patients, calcium binding activity and calcium binding protein (CaBP) content were measured in intestinal biopsies from 12 uremic patients (glomerular filtration rate〈5.0 ml/min) and 12 adult controls. Values for both were found to vary with the site of biopsy, highest values being obtained in the duodenal bulb, with lower values distally. Values for activity correlated with values for CaBP content in both normals and uremics and no difference was observed between groups. Levels of calcium binding activity and content of CaBP did not correlate with serum immunoreactive parathormone levels, but were directly related to circulating 25-hydroxycholecalciferol (25-OHD) levels. The data show that intestinal CaBP is normal in activity, quantity, and affinity for calcium in malabsorbing uremic patients, and are consistent with the hypothesis that calcium malabsorption in uremia is unrelated to deficiency of intestinal calcium binding protein.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02441187
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  • 5
    Electronic Resource
    Electronic Resource
    Precipitation of calcium phosphates from electrolyte solutions V. The influence of citrate ions (1979)
    Springer
    Calcified tissue international 28 (1979), S. 131-136 
    Details
    ISSN: 1432-0827
    Keywords: Calcium ; Phosphate ; Citrate ; Precipitation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The influence of citrate ions on the precipitation of crystalline apatitic precipitates with low Ca/P molar ratios [octacalcium phosphate (OCP) and calcium-deficient apatites (DA) (system A)] and of the intercrystalline mixtures of calcium hydrogen phosphate dihydrate (DCPD) and DA (system B) was investigated. Samples were prepared by direct mixing of calcium chloride solutions (A, 6·10−3 mol dm−3; B, 1·10−1 mol dm−3) and sodium phosphate solutions (A, 6·10−3 mol dm−3; B, 2·10−2 mol dm−3) containing citrate (0–2·10−3 mol dm−3) and preadjusted to pH 7.4. In the presence of citrate ions: (a) crystal growth of OCP and DA was slowed down; (b) habit modification of DCPD crystals occurred; and (c) equilibration in intercrystalline mixtures of DCPD and DA's was slowed down. All phenomena were caused by surface adsorption of negatively charged ions, most probably CaC6H5O7-, which is the prevalent calcium citrate species under the given experimental conditions. Habit modification of DCPD was induced by preferential adsorption at the (001) crystal plane.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02441231
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  • 6
    Electronic Resource
    Electronic Resource
    Disordered mineral metabolism produced by ketogenic diet therapy (1979)
    Springer
    Calcified tissue international 28 (1979), S. 17-22 
    Details
    ISSN: 1432-0827
    Keywords: Anticonvulsant ; Ketogenic diet ; Calcium ; Vitamin D ; Bone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Vitamin D and mineral metabolism status was examined in five children maintained chronically on combined ketogenic diet-anticonvulsant drug therapy (KG), and the results compared to those obtained in 18 patients treated with anticonvulsant drugs alone (AD) and 15 normal controls. KG patients exhibited biochemical findings of vitamin D deficiency osteomalacia: decreased serum 25-hydroxyvitamin D (25OHD) and calcium concentrations, elevated serum alkaline phosphatase and parathyroid hormone concentrations, decreased urinary calcium and increased urinary hydroxyproline excretion, and decreased bone mass. Although the KG and AD groups demonstrated similar reductions in serum 25OHD concentration, the KG patients exhibited a significantly greater reduction in bone mass. In response to vitamin D supplementation (5000 IU/day), mean bone mass in the KG group increased by 8.1±0.9% (P〈0.001) over a 12-month period. These results suggest that ketogenic diet and anticonvulsant drug therapy have additive deleterious effects on bone mass and that these effects are partially reversible by vitamin D treatment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02441213
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  • 7
    Electronic Resource
    Electronic Resource
    Precipitation of calcium phosphates under conditions of double diffusion in collagen and gels of gelatin and agar (1979)
    Springer
    Calcified tissue international 27 (1979), S. 171-176 
    Details
    ISSN: 1432-0827
    Keywords: Calcium ; Phosphate ; Precipitation ; Double diffusion ; Collagen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary One-dimensional double diffusion was applied to determine critical concentrations at which the precipitation of calcium phosphates occurs in reconstituted connective tissue collagen and agar gels at 37°C and in gelatin gels at 25°C. Experiments were performed in the presence of unbuffered 0.15 mol dm−3 NaCl, or 0.15 mol dm−3 NaCl-veronal adjusted to pH 7.4. It was found that critical concentrations of precipitation of both precipitating components, CaCl2 and phosphate buffer (pH 7.4), were equimolar and independent of the ratios of initial concentrations of the components. Critical concentrations of precipitation were not affected by the concentrations and kinds of gels used. The first-formed precipitates showed amorphous structure by X-ray diffraction analyses. Infrared (IR) spectra of the precipitates indicated CaHPO4 · H2O to be their predominant species. The molar Ca/P ratio obtained by chemical analyses was 1.08. This precipitate transformed in time into octacalcium phosphate. In all experiments, two very thin membranes of precipitate were formed in the gel column at the onset of precipitation simultaneously on both sides of the actual disc of precipitate. IR spectra and chemical analyses showed that both membranes were identical to the actual precipitation discs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02441181
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  • 8
    Electronic Resource
    Electronic Resource
    Factors affecting parathyroid hormone-induced hypophosphatemia and32P specific activity in thyroparathyroidectomized rats (1979)
    Springer
    Calcified tissue international 27 (1979), S. 239-246 
    Details
    ISSN: 1432-0827
    Keywords: Parathyroid hormone ; Calcium ; Plasma phosphate ; Bone phosphate ; Plasma32P ; Specific activity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Plasma changes in calcium, phosphate, and their radionuclides were studied in thyroparathyroidectomized (TPTX) rats treated with parathyroid hormone (PTH) for 8 h, this treatment starting 10 h after injection of45Ca and32P. Prior to intravenous infusion or hourly injections of PTH (10 mU/g/h), rats were maintained in one of three ways: on an extended fast (24 h); on a partial fast (10 h); or provided with 10% glucose and 1% calcium lactate overnight as a substitution for solid food. The pattern of change for plasma calcium,45Ca, and45Ca specific activity (S.A.) produced by PTH was not affected by these dietary conditions. The changes in phosphate were as follows: During the experimental (8 h) period, the rate of loss of32P from plasma in control rats was proportional to the length of the fast. This suggests that32P was released into plasma during the experimental period proportional to the ready availability of soft tissue glucose. In rats on an extended fast, PTH was phosphaturic, hypophosphatemic, and increased the rate of loss of32P from plasma without affecting32P S.A. values. In rats fasted for only 10 h, PTH produced similar effects on plasma phosphate and plasma32P values, but also caused a significant fall in plasma32P S.A. After glucose and calcium lactate treatment, PTH-induced phosphaturia was temporarily lost and the marked hypophosphatemia was replaced with a slight hyperphosphatemia. Plasma32P values also rose slightly; therefore, no effect on32P S.A. was produced. It is concluded from these studies that as the result of the phosphaturia caused by PTH, the hypophosphatemia which is produced automatically changes the phosphate gradient between various body compartments, causing phosphate entry into plasma. The authors postulate that this phosphate entering plasma is withdrawn primarily from bone fluid and bone.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02441192
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  • 9
    Electronic Resource
    Electronic Resource
    Anticonvulsant drug-induced osteomalacia: Alterations in mineral metabolism and response to vitamin D3 administration (1979)
    Springer
    Calcified tissue international 27 (1979), S. 13-18 
    Details
    ISSN: 1432-0827
    Keywords: Anticonvulsants ; Calcium ; Vitamin D ; Parathyroid hormone ; Bone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Parameters of mineral metabolism were examined in 6 patients with moderately severe anticonvulsant drug-induced osteomalacia. Compared to 15 matched controls, the patients exhibited significantly reduced serum calcium, inorganic phosphate, and 25-hydroxyvitamin D concentration, elevated serum alkaline phosphatase and immunoreactive parathyroid hormone (iPTH) concentration, reduced intestinal47Ca absorption, reduced urinary calcium and increased urinary hydroxyproline excretion, and reduced forearm bone mass. Intestinal absorption of vitamin D3 was normal. Following 4 months of treatment with vitamin D3 (4000 units/day), serum 25-OHD concentration was increased to 3 times mean normal values and all parameters except serum iPTH, urinary calcium excretion, and forearm bone mass were returned to levels not significantly different from normal. Serum iPTH concentration was reduced by 39% (P〈0.05); 24-h urinary calcium excretion rose by 98% (P〈0.001), and forearm bone mass increased by 5.6% (P〈0.05). It is concluded that moderate-dose vitamin D3 supplementation is effective in normalizing parameters of mineral metabolism in this disorder, despite evidence of resistance to the biologic effects of vitamin D.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02441155
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  • 10
    Electronic Resource
    Electronic Resource
    The calciuria of increased fixed acid production in humans: Evidence against a role for parathyroid hormone and 1,25(OH)2-vitamin D (1979)
    Springer
    Calcified tissue international 28 (1979), S. 233-238 
    Details
    ISSN: 1432-0827
    Keywords: Calcium ; PTH ; 1,25(OH)2D ; Acid ; Bone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary We measured mineral and acid balances, serum iPTH, urinary cAMP/creatinine, and plasma concentrations of 25OHD and 1,25(OH)2D in 7 healthy adults during control conditions and during increased fixed acid production achieved either by the administration of NH4Cl (N=3) or by increased dietary protein intake (N=4). When acid production was increased, the subjects were in positive acid balance and negative Ca balance because of increased urinary Ca excretion. Serum iPTH fell slightly but urinary cAMP and the plasma levels of vitamin D metabolites did not change. We conclude that the accelerated skeletal and urinary losses of Ca that occur when fixed acid production is increased are not contributed to nor compensated for by the parathyroid-vitamin D endocrine systems.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02441241
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  • 11
    Electronic Resource
    Electronic Resource
    Vaterite, a constituent of the eggshells of the nonparasitic cuckoos,Guira guira andCrotophagi ani (1979)
    Springer
    Calcified tissue international 29 (1979), S. 63-69 
    Details
    ISSN: 1432-0827
    Keywords: Vaterite ; Calcium ; Eggshells ; Cuckoos
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The crystalline spherules occurring in patches on the outer surface of the eggshells ofGuira guira and the bloom on the entire outer surface of those ofCrotophagi ani were shown by X-ray diffraction analysis to be vaterite.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02408056
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  • 12
    Electronic Resource
    Electronic Resource
    Regulation of calcium transport in isolated periosteal cells, effects of hormones and metabolic inhibitors (1979)
    Springer
    Calcified tissue international 29 (1979), S. 155-161 
    Details
    ISSN: 1432-0827
    Keywords: Periosteal cells ; Calcium ; PTH ; CT ; Metabolic inhibitors
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Calcium transport was studied in cells isolated from cultured periostea of 18-day-old chick embryos. Net calcium uptake was stimulated by iodoacetate (IAA) and inhibited by dinitrophenol (DNP). Calcium efflux from the intracellular compartment was inhibited by IAA. Changes in the extra-or intracellular sodium concentration had only minor effects on calcium transport. This indicates that calcium efflux from periosteal cells is probably directly dependent on ATP hydrolysis, whereas calcium-sodium exchange is of less importance. The cation ionophore A23187 stimulated calcium uptake during short incubations but was inhibitory in long incubations. The possible involvement of the mitochondria in this effect is discussed. Parathyroid hormone (PTH) and calcitonin (CT) stimulated the net uptake of calcium in relatively low doses (both 0.01 U/ml or higher). The effects of the hormones on net calcium uptake were not additive. Calcium efflux was not changed in the presence of PTH or CT.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02408071
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  • 13
    Electronic Resource
    Electronic Resource
    Phytochrome-mediated uptake of calcium in Mougeotia cells (1979)
    Springer
    Planta 146 (1979), S. 31-39 
    Details
    ISSN: 1432-2048
    Keywords: Autoradiography ; Calcium ; Mougeotia ; Phytochrome
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Ca2+ is proposed to function as a messenger in such phytochrome-mediated responses as localized cell growth, intracellular movements, and control of plasma membrane properties. To test this hypothesis, the uptake of Ca2+ in irradiated and non-irradiated regions of individual threads of the green alga Mougeotia was studied with the aid of 45Ca2+ and low temperature autoradiography: 10–20 cells within 40–60 cell-long threads were irradiated for up to 1 min, transferred to darkness for 3 to 10 min, submersed in a radioactive medium for 1 min, washed in an unlabelled medium for 30 min, and then autoradiographed at-80° C for several days. The autoradiographs show that those cells which had been pre-irradiated with red light did take up 2–10 times more Ca2+ than the adjacent non-irradiated cells of the same thread. Cells pre-irradiated with farred light or red light followed by far-red light showed no enhanced uptake of Ca2+. These results might be interpreted to indicate, firstly, that phytochrome-Pfr is involved in the enhanced uptake of Ca2+ and secondly, that the accumulation of radioactive Ca2+ in red light irradiated cells is an expression of an increased intracellular concentration of Ca2+. This interpretation is based on the data that (i) the dark interval between irradiation and labelling precluded the involvement of photosynthesis, (ii) the effect of red light was reversible with far-red light, and (iii) the accumulation of Ca2+ persisted during the long wash-out period. We speculate, that the red light-enhanced accumulation of Ca2+ in Mougeotia cells is caused by a Pfr-mediated increase of the Ca-permeability of the plasma membrane, and perhaps by a Pfr-impeding of an active Ca2+-extrusion.
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    URL: http://dx.doi.org/10.1007/BF00381252
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    Forced calcium entry and polarized growth of Funaria spores (1979)
    Springer
    Planta 144 (1979), S. 401-406 
    Details
    ISSN: 1432-2048
    Keywords: A23187 gradients ; Calcium ; Germination (moss spores) ; Electric fields-Funaria ; Ionophore gradient ; Moss spores-Polarization ; Spores (moss)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We have used both steady electric fields, and gradients of the divalent ionophore, A23187, to control the point at which rhizoids emerge from spores of the common moss Funaria hygrometrica. The spores were grown in a medium containing calcium nitrate as the only major salt. Spores tend to form rhizoids towards the positive electrode, with a half maximal response to a difference of 4–8 mV across each cell. They also tend to form rhizoids towards the end of higher ionophore concentration in response to A23187 gradients. Both of these responses are the same at pH 5.5 and 8.0. Our tentative explanation is that Funaria spores tend to form rhizoids where most calcium enters. However, the point of chloronema emergence is scarcely affected by steady fields of up to 45 mV/cell. Moreover, when steady fields are applied across already developed rhizoids or chloronemata, their subsequent growth is directed towards the negative electrode in both cases, with rhizoids giving a 50% response at only 3—5 mV/cell, and chloronemata being less responsive.
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    Interaction of bovine rhodopsin with calcium ions (1979)
    Springer
    European biophysics journal 5 (1979), S. 33-41 
    Details
    ISSN: 1432-1017
    Keywords: Rhodopsin ; Calcium ; Reaction kinetics ; Regeneration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
    Notes: Abstract The formation of metarhodopsin II in various bovine rhodopsin preparations (rod outer segment (ROS) suspensions and rhodopsin-detergent solutions) was measured by means of flash spectrophotometry. The half-lifetime and formation of metarhodopsin II in ROS did not depend on the calcium concentration in the range of less than 10−9 M (using EGTA or EDTA) to 15×10−3 M calcium at pH values of 5.0, 7.1, and 9.0 (Table 1). The regeneration of rhodopsin from opsin by adding 11-cis retinal to ROS-suspensions and rhodopsin digitonin solutions was measured spectrophotometrically. It was not substantially different in either saline, one containing less than 10−7 M calcium (by adding EGTA), the other containing 10−3 M calcium (Table 2).
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    The effects of Mn2+ and Ca2+ on the prolonged depolarising after-potential in barnacle photoreceptor (1979)
    Springer
    European biophysics journal 5 (1979), S. 223-230 
    Details
    ISSN: 1432-1017
    Keywords: Prolonged depolarising after-potential (PDA) ; Visual pigment ; Invertebrate photoreceptor ; Manganese ; Calcium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
    Notes: Abstract We have studied the effects on the PDA of modifying intracellular and extracellular concentrations of Ca2+ and Mn2+. The effect of decreased Ca2+ concentration or addition of EGTA is mainly an increase in the PDA amplitude and length. Raising Ca2+ concentration using ruthenium red or high external Ca2+ has the opposite effect. The effect of Mn2+ is much more striking: In the presence of 50–100 mM Mn2+ the PDA is initially greatly depressed but can rise slowly for up to 20 or 30 s (in the dark) until it approaches its original amplitude and time course. Bridge measurements showed that the depression of the PDA corresponds to a depressed conductance and so is not due to an increase in K+ conductance. The Mn2+ effect is potentiated by decreased Ca2+. Appropriate stimulation suppresses the rising PDA as promptly as it does a normal PDA, suggesting that if lateral diffusion is the source of the slow rise, the PDA and PDA-depressing processes must be spatially linked. The action of the anti-PDA is apparently prolonged by both Ca2+ and Mn2+.
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    An ultrastructural study of iron and manganese deposition associated with extracellular polymers of pedomicrobium-like budding bacteria (1979)
    Springer
    Archives of microbiology 123 (1979), S. 213-226 
    Details
    ISSN: 1432-072X
    Keywords: Pedomicrobium ; Budding bacteria ; Iron deposition ; Manganese deposition ; Polymer ; Fine structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Morphological characteristics of two Pedomicrobium-like budding bacteria are described. A structured surface layer was regularly observed on strain 868. Ruthenium red- and Alcian blue-staining polymers were found on both strains. When either strain was grown in the presence of iron or manganese, the corresponding oxides accumulated on their surfaces. In thin sections iron oxides appeared as fine threads, arrays of particles or dense coatings, depending on the source of iron. Manganese oxides appeared as branching filaments or convoluted ribbons. Both metal oxides stained with ruthenium red. Extraction of the oxides followed by ruthenium red staining revealed that polyanionic polymers previously deposited on the cells were associated with the metals. Treatment of cultures with glutaraldehyde, HgCl2, or heat, inhibited manganese but not iron deposition, suggesting that iron oxides accumulated by passive, non-biological processes. Manganese oxides apparently accumulated under control of a biological manganese-oxidizing factor. Incomplete inhibition of manganese deposition observed in cell suspensions suggested that, if the oxidizing factor was an enzyme, it was unusually stable. Based on these results, possible mechanisms of iron and manganese deposition in association with extracellular polymers are suggested.
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    URL: http://dx.doi.org/10.1007/BF00406653
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    Effect of external factors on phototaxis of Chlamydomonas reinhardtii (1979)
    Springer
    Archives of microbiology 123 (1979), S. 93-99 
    Details
    ISSN: 1432-072X
    Keywords: Movement ; Phototaxis ; Cations ; Chlamydomonas ; Calcium ; Lanthanum ; Circadian rhythms
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effects of several cations on phototaxis of Chlamydomonas reinhardtii have been studied with the aid of an automated phototaxis monitoring device, coupled with a continuous culture. Sodium, potassium and magnesium ions, if added to the complete nutrient medium, have only slight effects on phototaxis at lower concentrations (10-3 mol), but inhibit at higher concentrations (10-2 mol). This inhibitory effect is not specific because motility is also impaired. Addition of 10-3 mol calcium enhances the phototactic reaction for some hours, but then the stimulation decreases gradually. Addition of 10-2 mol calcium causes strong inhibition. However, the reactivity recovers gradually during the following hours. If 10-3 mol potassium which does not influence phototaxis if added alone is applied simultaneously with calcium, the stimulation by calcium is enhanced. By the addition of 5·10-4—2·10-3 mol Ca2+ or Ca2++K+ cicadian rhythms with an average period length of 24 h are initiated which damp out after 1–2 weeks. If the cells are grown in a calcium deficient medium or if calcium is removed, phototactic activity decreases to very low reaction values or to zero, but is drastically increased immediately after the addition of calcium. The stimulatory effect of Ca2+ ions is specific. Ca2+ cannot be fully substituted by Ba2+ or Sr2+, and phototaxis is reversibly inhibited by lanthanum which is known to inhibit the calcium pump.
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    The structure of cyanobacterial phycobilisomes: a model (1979)
    Springer
    Archives of microbiology 123 (1979), S. 113-127 
    Details
    ISSN: 1432-072X
    Keywords: Phycobilisomes ; Phycobiliproteins ; Cyanobacteria ; Chromatic adaptation ; Fine structure ; Photosynthesis ; Protein assembly
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Phycobilisomes, supramolecular complexes of water-soluble accessory pigments, serve as the major light-harvesting antennae in cyanobacteria and red algae. Regular arrays of these organelles are found on the surface of the thylakoid membranes of these organisms. In the present study, the hemi-discoidal phycobilisomes of several species of cyanobacteria were examined in thin sections of cells and by negative staining after isolation and fixation. Their fundamental structures were found to be the same. Isolated phycobilisomes possessed a triangular core assembled from three stacks of disc-shaped subunits. Each stack contained two discs which were ∼12 nm in diameter and ∼6–7 nm thick. Each of these discs was probably subdivided into halves ∼3–3.5 nm thick. Radiating from each of two sides of the triangular core were three rods ∼12 nm in diameter. Each rod consisted of stacks of 2 to 6 disc-shaped subunits ∼6 nm thick. These discs were subdivided into halves ∼3 nm thick. The average number of discs of ∼6 nm thickness forming the peripheral rods varied among the strains studied. For certain chromatically adapting strains, the average rod length was dependent upon the wavelength of light to which cells were exposed during growth. Analyses of phycobilisomes by spectroscopic techniques, polyacrylamide gel electrophoresis, and electron microscopy were compared. These analyses suggested that the triangular core was composed of allophycocyanin and that the peripheral rods contained phycocyanin and phycoerythrin (when present). A detailed model of the hemi-discoidal phycobilisome is proposed. This model can account for many aspects of phycobiliprotein assembly and energy transfer.
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    URL: http://dx.doi.org/10.1007/BF00446810
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    Characterization of the cytoplasmic fibrils of Treponema refringens (Nichols) (1979)
    Springer
    Archives of microbiology 120 (1979), S. 205-213 
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    ISSN: 1432-072X
    Keywords: Cytoplasmic fibrils ; Treponemes ; Treponema refringens ; Fine structure ; Cell lysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The cytoplasmic fibrils of Treponema refringens were studied in situ by electron microscopy of thin sectioned and negatively stained cells. From 5 to 21 parallel fibrils ran through the cell in a band adjacent to the inner side of the cytoplasmic membrane, on the inner sides of the curves of the spirochete. The nuclear areas of cells were adjacent to the fibrils. Cross sections of fibrils isolated from cells which had been lysed were polygonal and not uniformly electron dense. Polyacrylamide gel electrophoresis of partially purified fibril preparations indicated their main component to be a protein with a molecular weight of 97,000. Fibrils were solubilized by 1% trypsin, 1% pronase, 6 M urea, 1 N HCl, 0.005 N NaOH or 1.3% sodium dodecyl sulfate. By electron microscopy of negatively stained isolated fibrils, each fibril was found to be a complex arrangement of strands rather than a single tubule.
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    Fine structure of the transitional zone of the rat seminiferous tubule (1979)
    Springer
    Cell & tissue research 198 (1979), S. 441-454 
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    ISSN: 1432-0878
    Keywords: Testis ; Rat ; Seminiferous tubule ; Transitional zone ; Fine structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary An electron microscopic study was made on the structure of the testicular transitional zone (TZ) in the adult rat. The TZ proper consists of modified Sertoli cells, with only a few spermatogonia and macrophages, surrounding distally a very narrow lumen. The TZ Sertoli cells have nuclei with a somewhat coarser matrix and more peripheral heterochromatin than Sertoli cell nuclei of the nearby seminiferous tubules, and the electron density of the cytoplasm varies from cell to cell. Smooth endoplasmic reticulum is abundant, but usually there are also scattered ribosomal rosettes and an occasional profile of rough endoplasmic reticulum. Microtubules are very numerous in the columnar portion of the cell, and laminar structures seemingly joining the cell surfaces are sometimes seen. Lipid droplets and lysosomal structures are frequent cellular components in proximal TZ Sertoli cells. Empty intracellular vacuoles are abundant, sometimes arranged around areas of smooth endoplasmic reticulum. Occasionally, membrane-limited fine granules and vacuoles are seen within Sertoli cells and also in the TZ lumen, suggesting a possible secretory activity by these cells. The apical processes of the Sertoli cells form large vacuolar structures, and in the basal parts of the epithelium vacuoles with capillary-like appearance are frequently seen. Phagocytosis of germinal cells by the Sertoli cells occurs in the proximal region of the TZ. Round waste bodies in contact with the Sertoli cell apices protruding into the tubulus rectus, are also common. The tunica propria of the TZ is thickened and somewhat wrinkled, and in the proximal region the myoid cell layer loses its continuity and is replaced by fibroblasts. The epithelium of the tubulus rectus adjacent to the TZ consists of several overlapping epithelial cells. The typical junctional complexes between TZ Sertoli cells appear to be impermeable to the lanthanum tracer.
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    Calcium binding sites in the vesicles of the carotid and aortic body chief cells (1979)
    Springer
    Cell & tissue research 199 (1979), S. 145-151 
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    ISSN: 1432-0878
    Keywords: Carotid body ; Aortic body ; Calcium ; X-ray microanalysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Chief cells of the carotid and aortic body chemoreceptors possess numerous cytoplasmic dense-core vesicles which are known to contain primarily dopamine. Following fixation in solutions containing 50 mM CaCl2, a 20–30 nm electron-dense particle (EDP) is often observed eccentrically located in many of the vesicles. Approximately 44 % of the carotid body and 16 % of the aortic body vesicles contain an EDP. The EDP probably represents the Ca+ + binding site critical to the stimulus-secretion coupling events culminating in exocytosis of these vesicles. The presence of Ca+ + in the cytoplasmic vesicles was verified by electron probe X-ray microanalysis.
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    Studies on fish scale formation and resorption (1979)
    Springer
    Cell & tissue research 201 (1979), S. 409-422 
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    ISSN: 1432-0878
    Keywords: Fish scale ; Fine structure ; Calcification ; Fibrillary plate ; Carassius auratus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Electron microscopic investigation of scales of the goldfish Carassius auratus revealed that the lamellae of fibrillary plates contain sheet-like structures composed of vertically oriented collagen fibers embedded in an organic matrix. The fibers (TC fibers) are smaller in diameter (35–45 nm) than those of the lamellae and the matrix is stained intensely with lead citrate. The sheet-like structures as well as the lamellae are formed by fibroblasts located beneath the lamellae. The orientation of the collagen fibers of the sheets and the lamellae seems to be controlled by the orientation of the ridges and invaginations of the surface of the fibroblasts. The fibrillary plate of C. auratus was found to be partially calcified. Calcification was initiated by the deposition of needle-like or flaky crystals of hydroxyapatite in the organic matrix of the sheet-like structure and proceeded into the TC fibers and the matrix region of the lamellae. The potassium pyroantimonate-osmium tetroxide method showed a heavy concentration of calcium in the osteoblasts, fibroblasts, and in the matrix regions of the fibrillary plate. Calcium-containing precipitates were also present in the “hole zone” of the collagen fibers in the lamellae, but the significance of this location in calcification remains to be elucidated.
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    The abdominal muscle receptor organ in Astacus leptodactylus (Crustacea) (1979)
    Springer
    Cell & tissue research 202 (1979), S. 41-61 
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    ISSN: 1432-0878
    Keywords: Abdominal muscle receptor organ ; Dendrites ; Fine structure ; Crayfish
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The structure of both the slow- and the fast-adapting abdominal muscle receptor organ of Astacus leptodactylus is described with particular reference to differences between the two systems. The receptors are composed of a thin muscle that extends from the front edge of one segment to the front edge of the following and a sensory cell connected with this muscle. In the zone where the sensory cells enter their respective muscle, muscle fibers are reduced (zone of relative muscle exclusion=ZRME) and partly replaced by connective tissue. The occurrence of dendritic processes of both the slow and the fast neurons is confined to this zone. The following differences between the two receptor types are established: (1) The fast receptor muscle reveals a smaller sarcomere length than the slow receptor muscle and a higher myosin/actin filament ratio. (2) Muscle fibers that pass the ZRME are always found at its periphery in the fast system, separated from dendritic processes by layers of connective tissue, while in the slow system muscle fibers frequently are intermingled with the sensory elements. (3) The ZRME of the slow receptor is 20–30% longer than that of the fast receptor. (4) The dendritic varicosities of the slow neuron, on an average, contain many more mitochondria than those of the fast neuron. (5) Dendritic processes (fine twigs as well as varicosities) are juxtaposed to the sarcolemma of the muscle fibers only in the slow system; in the fast system dendrites and muscle are spatially separated by connective tissue. It is assumed that these differences between the two receptor types arep at least in part responsible for the different thresholds observed in physiological experiments.
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    Side branch formation and orientation in the caulonema of the moss,Funaria hygrometrica: Normal development and fine structure (1979)
    Springer
    Protoplasma 100 (1979), S. 367-383 
    Details
    ISSN: 1615-6102
    Keywords: Cell polarity ; Fine structure ; Funaria caulonema ; Side branch formation ; Side branch orientation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The regular branching of theFunaria caulonema filaments is partly related to rhythms in nuclear and cell division. The formation and development of the branches were studied by light and electron microscopy with particular attention directed to the distribution of microtubules and the polar organization of the cytoplasm. The new side branch breaks through the wall of the mother cell. The site of branch development is determined by the position of the nucleus of the mother cell. In protonemata which grow in vertically placed Petri dishes gravity influences the position of nuclei and side branches, and also the direction of oblique cross walls in the caulonema filaments to a certain extent.
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    The fine structure of the antennal sensilla of the pine saw flyNeodiprion sertifer (Insecta: Hymenoptera) (1979)
    Springer
    Protoplasma 101 (1979), S. 111-126 
    Details
    ISSN: 1615-6102
    Keywords: Antennal sensilla ; Fine structure ; Neodiprion sertifer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary There is a considerable sexual dimorphism as regards the development of the antenna inNeodiprion sertifer. In the male this is manifested in a larger antennal surface area and the possession of a great number of long single-walled sensilla (SW 1), which are located on the antennal branches. In the female the antennal branches are vestigial, and the single-walled sensilla, of a second type (SW 2), are shorter and present in lower numbers. Both sexes have in addition four types of sensilla in common:viz. a third type of single-walled sensilla (SW 3), terminal pore sensilla, double-walled sensilla, and poreless sensilla. These four sensillar types are characterized not only by their external appearance but also by their internal morphology. Especially the cells enveloping the sensory cells vary in number and appearance.
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    The influence of humidity on the mineral composition of tomato plants with special reference to calcium distribution (1979)
    Springer
    Plant and soil 52 (1979), S. 427-435 
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    ISSN: 1573-5036
    Keywords: Ash alkalinity ; Calcium ; Cation distribution ; Humidity ; Magnesium ; Mineral composition ; Oxalate ; Pectate ; Tomato
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Tomato plants grown in water culture under two different humidity regimes (50% R.H. and 95% R.H.) were harvested at intervals over the growth period and cation uptake and calcium distribution investigated. The following results were obtained: 1. Plants in the high humidity regime initially grew faster but at the final harvest after 22 days, dry matter yields were the same. 2. In the high humidity treatment particularly towards the end of the experiment, the growth of the young leaves was disturbed and the plants showed symptoms resembling Ca or B deficiency. Analysis revealed that these tissues were lower in Ca than comparative tissues of the low humidity plants. The converse was true for B. 3. Cation uptake was little affected by the humidity treatment. However, the distribution of calcium within the plant was markedly influenced by humidity. In the high humidity treatment the level of Ca in the young leaves was very low and Ca accumulated in the stems. A high proportion of both Ca and Mg in these younger Ca deficient leaves was found to be associated with pectate. The same trend was observed in the stems, more of the Ca and Mg in this case being bound to oxalate as well as pectate. These results further indicate the possible significance of exchange movement of Ca particularly under low transpiration conditions when Ca transport by mass flow is restricted. 4. Xylem sap analysis showed a close cation-anion balance in all samples. NO3-ion was the predominant anion and the two major cations were K and Ca. This provides further evidence that the upper plant parts provide the major site of NO3-reduction in the tomato plant.
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    Fine structure of the agranular adenohypophysial cells in the hagfish, Myxine glutinosa (Cyclostomata) (1979)
    Springer
    Cell & tissue research 204 (1979), S. 67-75 
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    ISSN: 1432-0878
    Keywords: Adenohypophysis ; Hagfish ; Agranular cells ; Fine structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Agranular cells are found throughout the adenohypophysis of Myxine glutinosa. They are located at the margin of single hypophysial follicles in the form of a spongy epithelial net. Their relationship to the secretory cells of the adenohypophysis and their morphology are described in adult animals. The distribution and ultrastructure of the agranular cells in the hagfish are in good agreement with the pattern of comparable cells in other vertebrates.
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    The fine structural localization of acid phosphatase in pore cells of embryonic and newly hatched Deroceras reticulatum (Pulmonata: Stylommatophora) (1979)
    Springer
    Cell & tissue research 204 (1979), S. 253-265 
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    ISSN: 1432-0878
    Keywords: Pore cells ; Fine structure ; Acid phosphatase ; Cell lysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The fine structure of the pore cells in pre- and post-hatched Deroceras reticulatum is described. The cells have been divided into three main types on morphological grounds, one type being particularly rich in glycogen. Certain pore cells contain haemocyanin granules in grooves below cytoplasmic tongues, and in characteristic double-membrane-bounded vesicles within dilated cisternae of rough endoplasmic reticulum, as well as in other identified areas. All types of pore cells show fine fibres reminiscent of collagen associated with the basal lamina and pore complexes. In addition to acid phosphatase activity in lysosomes and Golgi elements, intra- and extracisternal activity has been demonstrated in association with the rough endoplasmic reticulum. The intracisternal activity is in close proximity to the Golgi apparatus and may represent enzyme that is about to enter the GERL system. Extracisternal activity may be associated with cellular lysis and death, or may represent local areas of degradation leading to cytodifferentiation. Remnants of lysed pore cells appear to be taken up by connective tissue amoebocytes.
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    Experimental examination of the possible influence of the 1.87 Å line emission on the fine structure of the lower ionosphere ionization (1978)
    Springer
    Pure and applied geophysics 116 (1978), S. 1-7 
    Details
    ISSN: 1420-9136
    Keywords: Continuous emission ; Fine structure ; Ionosphere ; Line emission
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Summary From the theoretical investigation ofLetfus andApostolov (1974) it follows that under flare conditions the intensive X-ray emission lines in the 1–8 Å range have an insignificant contribution to the ionization state of the lower ionosphere in comparison with the enhanced emission of the continuum. This result is experimentally confirmed by direct comparison of the intensity variations of the emission line 1.87 Å (Fe XXV) during the solar flare of 25 July 1967 measured onboard of the OSO III satellite with simultaneous ground observations of the ionization state variations of the lower ionosphere made by the A3 method.
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    The intestinal handling of calcium by the rat in vivo, as affected by cortisol. Effect of dietary calcium supplements (1978)
    Springer
    Calcified tissue international 25 (1978), S. 1-6 
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    ISSN: 1432-0827
    Keywords: Calcium ; Intestine ; Growth ; Cortisol ; Hydroxyproline ; Parathyroid hormone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary This paper reports the effects of cortisol on intestinal management of calcium and on related changes on bone metabolism. Five groups of 12 rats each fed a standard diet (0.8% Ca) received 2, 6, 16, 32, and 128 mg/kg/day of cortisol hemisuccinate, subcutaneously. After 16 days, intestinal absorption and excretion of Ca were measured with the aid of45Ca. True Ca absorption increased as a function of dose up to 16 mg/kg/day and remained high with the larger doses. Endogenous fecal Ca excretion increased exponentially as a function of the dose from 16 mg/kg/day onwards. Therefore, a dual effect was observed: (a) an increase in true Ca absorption at low cortisol doses (which increased net Ca absorption); and (b) an increase in endogenous fecal Ca excretion at high doses (which reduced net Ca absorption). In no case was a depression of true Ca absorption observed. Growth rate and food conversion efficiency were depressed only with a cortisol dose of 128 mg/kg/day. The urinary excretion of hydroxyproline, pyrophosphate, and aminopolysaccharides decreased with low doses and increased above normal levels with the highest dose. When animals treated with 128 mg/kg/day of cortisol were fed Ca-enriched diets, net Ca absorption improved. Simultaneously, growth rate and food conversion efficiency approached normal values. In these experiments, net absorption of Ca was found to be inversely related to urinary excretion of hydroxyproline. The urinary rate of excretion of hydroxyproline is suggested as an indicator of the effect of a Ca supplement on cortisol affected connective tissue turnover.
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    URL: http://dx.doi.org/10.1007/BF02010743
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    Effects of a single dose of fluoride on calcium metabolism (1978)
    Springer
    Calcified tissue international 26 (1978), S. 199-202 
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    ISSN: 1432-0827
    Keywords: Fluoride ; Calcium ; Phosphate ; Parathyroid hormone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Fluoride 27 mg was given perorally to 14 subjects. It was found that the serum fluoride concentration increased followed by a decrease to normal levels during 24 h. Serum concentrations of calcium and phosphate decreased initially whereas those of serum immunoreactive parathyroid hormone increased. After 24 h the measured quantities were within normal limits. The results are discussed with reference to mineralization of hard tissues and to fluoride treatment of osteoporotic patients.
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    URL: http://dx.doi.org/10.1007/BF02013258
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    Potentiation of the effects ofSolanum malacoxylon extracts on rat intestinal phosphate and calcium absorption by incubation with ruminal fluid (1978)
    Springer
    Calcified tissue international 26 (1978), S. 215-219 
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    ISSN: 1432-0827
    Keywords: Solanum malacoxylon ; Vitamin D metabolites ; Rickets ; Phosphate ; Calcium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The effects of a partially purified aqueous extract ofSolanum malacoxylon (SM) leaves and of an SM extract incubated with ruminal fluid (RF) prior to administration on intestinal phosphate and calcium absorption in rachitic rats were compared with 1α, 25-dihydroxy-vitamin D3[1α,25-(OH)2-D3] using a duodenal loop in situ method. The time course responses elicited by both extracts were qualitatively similar to that of 1α, 25-(OH)2-D3. However, a single dose of SMRF was significantly more effective in stimulating32P absorption than an equivalent dose of SM. Part of this difference can be accounted for by incomplete saturation of the phosphate transport system with the level of SM employed. Treatment with rumen potentiated the effects of SM on45Ca absorption to a lesser extent. Extraction of SMRF with nonpolar organic solvents and purification of the lipid extract by chromatography on Silica Gel G thin-layer plates and on Sephadex LH-20 columns yield two fractions which promote intestinal32P absorption. The bioactive fraction eluting first from the Sephadex LH-20 column migrates similarly as 1α,25-(OH)2-D3. The greater effectiveness of SMRF extracts on intestinal phosphate and calcium absorption may be tentatively attributed to the release of 1α,25-(OH)2-D3 from the corresponding glycoside, shown previously to be present in SM, and to steroid modification during incubation with rumen.
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    URL: http://dx.doi.org/10.1007/BF02013261
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    Selective stimulation of net calcium efflux from chick embryo tibiae by parathyroid hormone in vitro (1978)
    Springer
    Calcified tissue international 25 (1978), S. 227-232 
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    ISSN: 1432-0827
    Keywords: Parathyroid hormone ; Bone ; Calcium ; Chick embryo ; Organ culture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The purpose of this study was to measure in an in vitro system the movement of Ca and phosphate (Pi) out of bone when treated with parathyroid hormone (PTH). Tibiae from 13-day chick embryos were incubated for up to 8 h in a defined medium containing 1.8 mM Ca. Medium samples were collected every 2 h and were analyzed for Ca, Pi and lactate. Net effluxes from the bones were calculated. When bones were incubated with PTH in the medium (1 U/ml), net Ca efflux was increased 44, 60 and 100% at 4, 6 and 8 h, respectively. At no time was net Pi efflux affected by the hormone. The well known PTH-stimulated lactate production was not seen until 8 h. Lower doses of PTH (0.1 and 0.3 U/ml) were also effective. Comparing PTH (1 U/ml) responsiveness at higher (2.2 mM) and lower (0.9 mM) medium Ca concentrations, showed that with 2.2 mM Ca no increased Ca efflux was seen, while with 0.9 mM Ca significant elevation in medium Ca occurred 2 h sooner than in the experiments using 1.8 mM Ca. In another experiment, varying the medium Pi level from 1 to 2 mM had no effect on the Ca response to PTH. In neither experiment was Pi release affected by PTH. The results of this study have led to the following conclusions: (1) PTH acts on bone to cause an early dose related increase in net Ca efflux; (2) the effect is specific for Ca, since it is not accompanied by an increased Pi efflux, and may be saturated by raising the medium Ca level; and (3) PTH-stimulated Ca efflux in this system is not correlated with, and is probably not a result of increased lactate production.
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    URL: http://dx.doi.org/10.1007/BF02010774
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    Influence of partially purified extracts ofSolanum malacoxylon on bone resorption in organ culture (1978)
    Springer
    Calcified tissue international 26 (1978), S. 39-45 
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    ISSN: 1432-0827
    Keywords: Solanum malacoxylon ; Bone culture ; Resorption ; Calcium ; Osteoclasts
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The water-soluble active principle of the plantSolanum malacoxylon (SM) was partially purified by column chromatography, and its bone-resorbing activity was tested by using an organ culture system of 18-day fetal mouse fibulae prelabeled with45Ca. Three series of experiments were performed. In the first series, the aqueous extract of SM was submitted to Sephadex G-25 chromatography to separate the active substances. From six collected fractions only two exhibited reproducible bone-resorbing activity as indicated by an increased release of45Ca from bone rudiments. In the second series, the active fractions were combined and lyophilized to a powder which was dissolved in the culture media to obtain the concentrations of 5, 25, 50, and 100 μg/ml. The addition of this saltfree material resulted in a dose-related accentuation of45Ca release from fetal mouse bones into the medium. Histologically, the treated fibulae showed greater numbers of osteoclasts than the controls and a disappearance of bone trabeculae. In the third series, the active material was further purified on Sephadex LH-20 column. From four collected fractions, only one showed bone-resorbing activity in vitro. It is concluded that the purified active factor of SM exerts a direct effect on bone. It stimulates the mobilization of bone calcium in vitro by increasing the population of osteoclasts. The nature of the active principle remains unknown.
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    A proposed cellular mechanism for calcium transport in the intestinal epithelial cell (1978)
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    Calcified tissue international 26 (1978), S. 71-79 
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    ISSN: 1432-0827
    Keywords: Absorption ; Calcium ; Mitochondria ; Intestinal epithelium ; Potassium-pyroantimonate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Intracellular transport of calcium from the apical to the basal-lateral region of the intestinal epithelial cell was invetigated in duodenum from normal fed, fasted, and calcium-loaded rats. The process was followed with time using electron microscopy with potassium pyroantimonate to precipitate calcium. The observations made were subjected to morphometric analysis. The specificity of the method was demonstrated in the villus cell by resistance to micro-incineration and by absence of deposits following exposure to EGTA. Using this method calcium was seen in cells from calcium-fed rats at the microvillus border, in the Golgi zone, and within the internal compartments of the mitochondria. In cells from fasted rats calcium was not seen. Mitochondria were found largely at the apex of the cell and were free of detectable calcium. By 5 min, in the cells of fasted rats given a calcium load, the calcium had reached the Golgi apparatus and the inner mitochondrial compartment. After 15 min mitochondria were heavily loaded with calcium and had moved to the basal region of the cell. These observations suggest that mitochondria play an important role in absorption of calcium and appear to transport this ion from the apex to the basal region of the cell where entry into the capillaries takes place.
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    Calcium uptake and survival of Bacillus stearothermophilus (1978)
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    Archives of microbiology 119 (1978), S. 17-24 
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    ISSN: 1432-072X
    Keywords: Thermophilic bacteria ; Bacillus stearothermophilus ; thermostability ; Calcium ; Transport ; Survival
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The calcium transport in resting vegetative cells of Bacillus stearothermophilus was studied by determining the retention of 45Ca in a membrane filter assay. The kinetics of death by vegetative cells, when suspended in buffer at 55°C, was also investigated. The calcium influx required the presence of an energy source, e.g. glucose-1-phosphate and the system exhibited saturation kinetics. The requirements for survival of the thermophilic cells reflected those of the calcium transport system. Thus, cells treated with nitrogen gas showed an increased thermal stability and a decreased efflux of calcium. The initial velocity of calcium influx correlated linearly with the survival of the cells after 1 min heating at 55° C. Lanthanum inhibited calcium influx and reduced survival. Magnesium did not inhibit calcium influx but could replace calcium as a stabilizing agent. The results suggest that the thermophilic cells are not intrinsically heat stable but survive due to a high cellular concentration of divalent ions.
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    URL: http://dx.doi.org/10.1007/BF00407922
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    Local degenerative changes in the drum muscles of piranhas (Serrasalminae, Characidae) (1978)
    Springer
    Cell & tissue research 188 (1978), S. 75-82 
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    ISSN: 1432-0878
    Keywords: Drum muscles ; Piranha ; Degenerative changes ; Fine structure ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In the posterior drum muscle of the piranha structural alterations are frequently observed. Electron microscopic studies revealed a disordering of the myofibrils in these regions, accompanied by conspicuous changes in the mitochondria. As the degree of disorder increases, the mitochondrial cristae initially swell to form vesicles. Eventually the mitochondria become filled with myelin-like lamellar structures, which in many cases coalesce to form a dense outer wall. A striking concentration of lysosomes into localized masses was also characteristic of these regions.
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    Light and electron microscopy of the ducts and their subepithelial tissue in the rat ventral prostate (1978)
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    Cell & tissue research 192 (1978), S. 381-390 
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    ISSN: 1432-0878
    Keywords: Prostatic duct ; Epithelium ; Basal cell ; Muscular coat ; Fine structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The ducts of the rat ventral prostate have been studied by light and electron microscopy for elucidation of their role in prostatic function. The epithelium of the main duct consists of simple columnar cells and polymorphic basal cells. The columnar cells show no indication of secretory activity. The basal cells contain bundles of filaments of 5–6 nm thickness and numerous pinocytotic vesicles. The ducts are surrounded by layers of circular smooth muscle cells interspersed with nerve axons. On ultrastructural grounds the ducts do not appear to secrete material into the seminal fluid, but apparently the muscular coat actively helps drain the gland during ejaculation.
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    Catharanthine: A novel stimulator of pancreatic enzyme release (1978)
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    Cell & tissue research 192 (1978), S. 277-284 
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    ISSN: 1432-0878
    Keywords: Pancreas ; Calcium ; Vinca alkaloids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The plant alkaloid, catharanthine, was shown to stimulate release of amylase from pancreatic fragments and to cause extensive degranulation of pancreatic acinar cells with accumulation of membrane material in the Golgi region. The extent and time course of maximal catharanthine stimulation was comparable to that induced by the cholinergic analog bethanechol. Antimycin inhibited the action of catharanthine while atropine did not. Removal of Ca2+ from the incubation medium inhibited amylase release induced by catharanthine but did not affect release induced by bethanechol. Catharanthine induced a delayed release of 45Ca2+ from prelabeled pancreatic fragments as compared to bethanechol. It is suggested therefore that catharanthine activates the physiological pathway controlling amylase release by causing a rise in cytoplasmic Ca2+ but the mechanism by which this occurs is different from that caused by physiological secretagogues.
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    Degradation of the radula in the snails Biomphalaria glabrata say and Limnaea stagnalis L. (Gastropoda, Pulmonata) (1978)
    Springer
    Cell & tissue research 193 (1978), S. 283-295 
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    ISSN: 1432-0878
    Keywords: Radula ; Degradation ; Fine structure ; Pulmonata
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The radula of snails is formed at the posterior end of the radular gland or pocket, and degraded at the same rate at its anterior end. Degradation is due to different secretory activities of the inferior epithelium of the radular gland. Its secretions seem to degrade enzymatically the matrix of the radular membrane and basal plates of teeth, leaving only chitin containing microfibres and degradation products. The sclerotized parts of the teeth remain unchanged, but as they are now only loosely connected with the radular membrane. they are torn off easily during feeding movements. The rest of the degraded and frayed radular membrane and the subradular membrane are also lost by abrasion during feeding. The cells of the inferior epithelium are connected with each other by septate desmosomes and an elaborate system of deep lateral interdigitation which may provide tensile strength. Extrusion of degraded cells of the inferior epithelium into the subradular membrane takes place, although the thick basal lamina forms a continuous sheath which is closely adjoined to the basal parts of the inferior epithelium. Nerve fibres containing vesicles with electron dense neurosecretory material (deduced from the diameter of 200–250 nm) are attached to this sheath or penetrate into it; they may be involved in the regulation of production and degradation processes during radula replacement. Problems of the forward transport of radula and inferior epithelium are discussed.
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    Cold-induced insulin release in vitro: Evidence for exocytosis (1978)
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    Cell & tissue research 194 (1978), S. 387-398 
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    ISSN: 1432-0878
    Keywords: Isolated pancreatic islets ; Temperature ; Exocytosis ; Insulin ; Calcium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Exposure of isolated pancreatic islets (mouse or rat) to low temperature (2° C) evoked a threefold increase in insulin release irrespective of the glucose concentration in the incubation medium. Cold-induced release was transient and rewarming to 37° C restored the sensitivity of B-cells to glucose stimulation. In islets cooled to 2° C, exocytotic profiles could easily be detected both by thin-section and freeze-fracture electron microscopy. As revealed by the freeze-fracture technique, the number of exocytotic profiles per membrane area was increased three-to fourfold as compared to islet cells incubated at 20° C. This was paralleled by intracellular fusion of secretory vesicles. Cold-induced insulin release was not affected by theophylline, cytochalasin B, omission of extracellular Ca++ or D600. Replacement of extracellular Na+ with choline or sucrose suppressed the increase in insulin release and in frequency of exocytotic profiles recorded after exposure to 2° C. It is suggested that a redistribution of Ca++ from intracellular stores, possibly mediated by an increase in intracellular Na+, triggers exocytosis of insulin granules upon exposure to cold.
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    The effect of the ionophore A23187 on amylase release, cellular integrity and ultrastructure of mouse pancreatic acini (1978)
    Springer
    Cell & tissue research 186 (1978), S. 287-295 
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    ISSN: 1432-0878
    Keywords: Pancreas ; Calcium ; Ionophore
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The effects of the Ca2+ ionophore A 2317 on pancreatic amylase and lactate dehydrogenase (LDH) release, cellular electrolyte balance and ultra-structure were studied with the use of incubated pancreatic fragments. A 23187 (0.3 μM) in the presence of Ca2+, increased amylase release but at higher concentrations (1–10 μM) also increased LDH release and increased uptake of 14C-sucrose with concomitant loss of tissue K+ and gain in Na +. The ultrastructure of the majority of acini appeared normal and showed depletion of zymogen granules. Microtubules and microfilaments which have been implicated in the release process were normal or increased in number. In the absence of Ca+ the ionophore had no effect on secretion, cellular integrity or ultrastructure. It is concluded that A 23187 in the presence of Ca2+ increases amylase release by a mechanism comparable to the terminal steps in stimulussecretion coupling induced by physiological secretagogues. This provides further evidence that amylase release is mediated by a rise in cell Ca2+ although the mechanisms of the ionophore- and physiological secretagogue-induced rise in Ca+ are probably different. High concentrations of ionophore (〉 1 μM) also induce Ca2+ dependent damage in a fraction of the cells.
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    Effects of reserpine administration on the fine structure of the rat pars intermedia (1978)
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    Cell & tissue research 194 (1978), S. 115-123 
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    ISSN: 1432-0878
    Keywords: Pars intermedia ; Fine structure ; Reserpine ; Freeze fracture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Hormone release from the pars intermedia is under inhibitory control of the hypothalamus. Control may be mediated via dopaminergic fibers which directly contact secretory cells. Administration of reserpine in vivo to adult male rats for four consecutive days results in major alternations in pars intermedia cytology. Cells show expanded areas and whorls of rough endoplasmic reticulum, as well as extensive Golgi zones with numerous dense granules. Some nerve fibers exhibit alterations in vesicle content, while others retain a more normal appearance. Freeze-fracture of glands from reserpine-treated animals provides evidence for exocytosis of granules, although such phenomena are not observed in thin sections. The ultrastructural findings suggest that reserpine alters the content of local inhibitory neurotransmitters in the pars intermedia, leading to unrestrained hormone release, followed by renewed granule synthesis.
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    Morphogenesis of larval cuticle in the polychaete Phragmatopoma lapidosa (1978)
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    Cell & tissue research 186 (1978), S. 187-201 
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    ISSN: 1432-0878
    Keywords: Egg envelope ; Polychaeta, Sabellariidae ; Larva ; Cuticle ; Fine structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The development of the egg envelope and its incorporation into the larval cuticle of the polychaete Phragmatopoma lapidosa, was studied by correlative scanning and transmission electron microscopy. The mature egg possesses an envelope composed of five zones including an outer granular zone formed by the tips of the egg microvilli. The formation of the granules is described and their functions are discussed. The entire egg envelope is retained as the larval cuticle up to the 16 h trochophore stage. From this stage to about the 60 h larval stage, the envelope is gradually lost and replaced by a cuticle consisting of branching microvilli. The cuticle of the 20 day larva is composed of highly branching microvilli penetrating a homogeneous electron opaque cuticle. The possible functions of the cuticle among the Annelida are discussed.
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    Calcium and sulphur in neurosecretory granules and calcium in mitochondria as determined by electron microscope X-ray microanalysis (1978)
    Springer
    Cell & tissue research 186 (1978), S. 453-463 
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    ISSN: 1432-0878
    Keywords: Neurosecretory granules (Insects) ; Mitochondria ; Calcium ; Sulphur ; Microanalysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Sections of neurosecretory cells fixed in glutaraldehyde and osmium tetroxide were studied by means of an EMMA-4 analytical microscope. Secretory granules in neurosecretory cells of the corpus cardiacum and of the brain, both in the desert locust Schistocerca and in the blowfly Calliphora, as well as neurosecretory granules in posterior pituitaries of the frog Rana and of the albino rat all contain a high concentration of calcium. A distinct sulphur peak was also a constant feature. In neurosecretory cells of the corpus cardiacum of Schistocerca the chromatin contained a high concentration of calcium. The mitochondria also contained much calcium, but part of this disappeared during preparation except when fixative and wash contained calcium chloride. By block staining with uranyl acetate most calcium is displaced from the mitochondria, whereas most of the calcium remains in the neurosecretory granules. Since the calcium peaks in spectra from neurosecretory granules appear of similar size, regardless of variations in the preparative procedure, this calcium must be firmly bound. The possible role of the calcium bound to the neurosecretory substance is discussed. The presence of sulphur in insect neurosecretory granules indicates the presence of a protein besides the hormone, i.e., an insect neurophysin.
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    The temperature dependency of45Ca diffusion in bovine enamel (1977)
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    Calcified tissue international 24 (1977), S. 173-177 
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    ISSN: 1432-0827
    Keywords: Enamel ; Calcium ; Diffusion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The diffusion of45Ca ions in sound bovine enamel at pH 7.0 was studied as a function of temperature in the range 20°–40°C. The experimental data show that the diffusion is governed by two processes with activation energies of about 0.7 and 1.3 eV respectively. These values are considerably larger than the activation energy of calcium ion diffusion in water (0.2 eV). The diffusion process with the activation energy of 1.3 eV is dependent upon the calcium concentration in solution. A model based on the complex pore structure of enamel and on interactions of diffusing ions with the enamel constituents is discussed.
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    Diffusion of45Ca in bovine enamel (1977)
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    Calcified tissue international 24 (1977), S. 59-64 
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    ISSN: 1432-0827
    Keywords: Enamel ; Calcium ; Exchange ; Diffusion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The penetration of45Ca ions into whole bovine enamel from an aqueous solution was studied as a function of the Ca content in the solution. A sectioning technique was employed to measure the penetration of45Ca into the enamel. Probably only Ca ions occupying surface positions in the hydroxyapatite crystallites participate in the exchange process at the solution-enamel interface. The fraction of Ca ions participating in the exchange was 2% of the total number of Ca ions. Two different diffusion processes occur; firstly, a process governed by a diffusion coefficient, D1 ranging from about 5×10−14 to 2×10−12 cm2/s and strongly dependent on the calcium concentration in the solutions; and secondly a process with a concentration-independent diffusion coefficient, D2, with a value of 2.8×10−12 cm2/s. It is assumed that the 2 diffusion types correspond to intra-and interprismatic transport, respectively. A model based on the pore structure of dental enamel and on surface charges on hydroxyapatite crystallites is discussed.
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    The measurement of Ca2+ effluxes from bone (1977)
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    Calcified tissue international 24 (1977), S. 113-117 
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    ISSN: 1432-0827
    Keywords: Bone membrane ; Calcium ; Ion fluxes ; Calvarium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary To facilitate the study of membrane function in the control of the flow of ions into and out of bone, it was desirable to develop a system for the direct quantitation of unidirectional effluxes of calcium and phosphate from bones. Based on a mathematical analysis of the problem, a specially designed Ussing chamber was developed which proved successful. Calvaria from 2-day-old rat pups, 3-day chicks and adult mice were evaluated. Calcium influxes which exceeded the corresponding effluxes were observed in the neonatal calvaria but not with those from adult mice. Also, an asymmetry in efflux was observed in rat calvaria, the inner side of the skull showed a higher efflux than did the external side. no such asymmetry was seen with calvaria from chicks or mice. This new technology should permit a further exploration of the role of the bone membrane in electrolyte homeostasis.
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    The effect of fluoride on bone of rats fed diets deficient in calcium or phosphorus (1977)
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    Calcified tissue international 22 (1977), S. 9-17 
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    ISSN: 1432-0827
    Keywords: Bone ; Fluoride ; Calcium ; Phosphorus ; Mechanical Strength
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract Four groups of weanling rats were fed for 2 weeks on a diet sufficient or insufficient in calcium and/or phosphorus. Each group was divided into four subgroups which were offered distilled water supplemented with 0, 50, 75, or 150 ppm fluoride. High levels of fluoride in drinking water inhibited weight gain. This inhibition was less in rats deficient in phosphorus than when normal-phosphorus diets were offered. At a low level, fluoride was without any effect on bone ash, thickness of femoral cortical bone, and mechanical strength, as measured by maximal load, ultimate stress to breaking, and limit of elasticity. Modulus of elasticity was decreased. At higher levels fluoride tended to decrease most of these parameters, except in rats deprived of both calcium and phosphorus. The effect of fluoride was modified by lack of dietary calcium and/or phosphorus and appeared to be weaker in rats deficient in these nutrients. Lack of dietary calcium and/or phosphorus decreased bone strength more than did fluoride content of water and of bone mineral. Concentration of bone ash and thickness of femoral cortical bone were closely correlated with parameters of mechanical strength.
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    On the state of anionic groups of demineralized matrices of bone and dentine (1977)
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    Calcified tissue international 22 (1977), S. 275-284 
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    ISSN: 1432-0827
    Keywords: Bone ; Calcium ; Collagen ; Dentine ; Phosphoprotein
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract Calcium-binding and biochemical studies have been applied to characterize the state of the carboxylate and protein-bound phosphate groups in the EDTA-demineralized matrices of rat bone and dentine. The organic phosphate and carboxylate content of demineralized bone is virtually identical to that of purified steer skin collagen whereas demineralized dentine has a significantly higher phosphate and carboxylate content, presumably due to the presence of an acidic non-collagenous phosphoprotein. Two classes of calcium-binding sites can be detected in demineralized bone, demineralized dentine, and purified, reconstituted collagen. The number of strong calcium-binding sites correlates with the number of protein-bound phosphate groups. Depending on the preparative procedure, seven to nine such sites (per collagen molecule) are present in dentine, and one to two in the purified reconstituted collagen and in bone. The binding constant for the dentinal sites (1.1×104 M−1), however, is 20 times greater than that for bone or reconstituted collagen fibrils from skin. We tentatively conclude that the strong calcium-binding site in bone and reconstituted collagen is of the form protein-PO 4 − Ca++ whereas in dentine it is of the form the weak binding sites in bone and dentine are of the form protein-COO-Ca++; and that approximately 160 of the 217 carboxylate groups of the collagen molecules of dentine or bone are present as electrostatic linkages of the form protein-COO−+H3N-protein.
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    URL: http://dx.doi.org/10.1007/BF02010366
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    A new tracer method for the calculation of rates of bone formation and breakdown in osteoporosis and other generalised skeletal disorders (1977)
    Springer
    Calcified tissue international 22 (1977), S. 191-206 
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    ISSN: 1432-0827
    Keywords: Bone ; Calcium ; Strontium ; Apposition ; Tracer analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract 1. Evidence has accumulated that the rate of acceretion (A) of calcium to bone is the sum of two fluxes; apposition involving the laying down of new bone and augmentation which is the result of slow exchange of non-surface bone calcium with plasma calcium pools as the result of solid state diffusion. 2. A method has been devised for separating A into its two components. It requires the use of45Ca or, for clinical studies,85Sr as a calcium tracer. Studies which are initiated with a combined accretion rate-calcium balance study, are concluded with an estimate of the exponent of the power function which has been found to describe the whole body retention of tracer from the second month onward. 3. The impulse response function of the skeleton for the tracer is then calculated, making the assumption that in any uniform volume of bone, osteoclastic resorption is a first order process. Making in addition certain simplifying assumptions, which are shown to have a modest influence on the final results, a mean rate of bone resorption can be calculated using a development of the well known Stewart-Hamilton formula. The apposition rate is calculated as the sum of the resorption rate and the calcium balance. Augmentation and diminution, defined as equal and opposite exchange processes, are given by the difference between A and the apposition rate. 4. The results of our first thirteen studies in normal subjects and patients with metabolic bone disease are presented, together with analyses of some data from the literature. It is concluded that the development of an atraumatic method for measuring rates of bone formation and resorption in the whole body would be an important advance in the study of metabolic bone disease, and this work is presented so that critical comparisons may be initiated between this tracer method and independent histological methods for measuring these parameters.
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    Calcium deficiency, pregnancy, and lactation in rats (1977)
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    Calcified tissue international 23 (1977), S. 87-94 
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    ISSN: 1432-0827
    Keywords: Calcium ; Osteoporosis ; Lactation ; Chemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The calcium homeostatic mechanism was challenged in adult female rats by feeding them a calcium-deficient diet containing oxalate, and by subjecting them to pregnancy and lactation. The regimen caused a substantial weight loss, especially in those animals which reared their young well. Severe hypocalcaemia was observed in the lactating rats. Serum-P was slightly elevated. The content of hydroxyproline in serum was considerably elevated, reflecting the degree of calcium deprivation. Serum proteins were least influenced. The calcium depriving regimen reduced the growth of long bones, but did not stop it. The ash content of the bones was considerably reduced, the degree of reduction depended on the degree of calcium deprivation. Ash as percentage of total bone organ was reduced, but not to the same extent as total ash. Analyses of different parts of femur showed that the proximal and distal parts had lost more bone mineral than the diaphyseal shaft. The ash content of cortical bone tissue from the femur was estimated by a volumetric method. No differences were observed between test groups and controls, indicating that no measurable amounts of bone mineral had been removed from the walls of the vascular canals or by osteocytic osteolysis. Planimetric determinations on cross sections from femora disclosed that a great amount of bone had been removed from the endosteal surface of the diaphysis, while the periosteal surface demonstrated reduced bone apposition.
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    The early mineralization of enamel (1977)
    Springer
    Calcified tissue international 24 (1977), S. 271-274 
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    ISSN: 1432-0827
    Keywords: Enamel ; Mineralization ; Calcium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The potassium pyroantimonate technique was used to study the cellular distribution of calcium during the early mineralization of enamel in rat molar tooth germs at the electron microscope level. Differing patterns of calcium distribution were observed in the ameloblast seemingly associated with the appearance of Tomes' process. In the early secretory ameloblast calcium pyroantimonate deposits were observed within the Golgi apparatus, within coated vesicles, within mitochondria and associated with the inner aspect of the cell membrane. However, with the development of Tomes' process the ameloblasts no longer demonstrated these discrete deposits of calcium pyroantimonate. Instead they showed a diffuse cytoplasmic staining pattern with no preference for any particular organelle.
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    A model-independent comparison of the rates of uptake and short term retention of47Ca and85Sr by the skeleton (1977)
    Springer
    Calcified tissue international 22 (1977), S. 183-189 
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    ISSN: 1432-0827
    Keywords: Calcium ; Strontium ; Bone ; Mathematical modelling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract 1. A method has been devised for comparing the impulse response functions of the skeleton for two or more boneseeking tracers, and for estimating the contribution made by measurement errors to the differences between any pair of impulse response functions. 2. Comparisons were made between the calculated impulse response functions for47Ca and85Sr obtained in simultaneous double tracer studies in sixteen subjects. Collectively the differences between the47Ca and85Sr functions could be accounted for entirely by measurement errors. 3. Because the calculation of an impulse response function requires fewera priori assumptions than other forms of mathematical analysis, and automatically corrects for differences induced by recycling of tracer and non-identical rates of excretory plasma clearance of tracer, it is concluded that differences shown in previous in vivo studies between the fluxes of*Ca and*Sr into bone can be fully accounted for by undetermined oversimplifications in the various mathematical models used to analyse the results of those studies.85Sr is therefore an adequate tracer for bone calcium in most in vivo studies.
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    Localisation histochimique du calcium dans la colloïde des vésicules thyroïdiennes du rat (1977)
    Springer
    Calcified tissue international 24 (1977), S. 275-278 
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    ISSN: 1432-0827
    Keywords: Calcium ; Thyroid ; Calcium ; Thyroïde
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé Les auteurs utilisent une solution de Glyoxal bis 2-hydroxyanil à basse température pour localiser le calcium dans la thyroïde. Grâce à cette technique qui limite les mouvements ioniques, ils observent que le calcium situé principalement dans la colloïde est résorbé en même temps qu'elle lors d'une stimulation par le froid.
    Notes: Summary With a Glyoxal bis 2-hydroxyanil alcoholic solution at −25°C, the calcium was localized in frozen thyroid slices. The limited ionic movement permits seeing that the calcium situated principally in the colloid is resorbed at the same time by a low temperature stress.
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    Our present knowledge of calcium or hydrogen ions as transmitters in the vertebrate rod outer segments (1977)
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    European biophysics journal 3 (1977), S. 55-58 
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    ISSN: 1432-1017
    Keywords: Rhodopsin ; Rods ; Phototransduction ; Calcium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
    Notes: Abstract Difficulties in testing the possible role of calcium as a Transmitter in the R.O.S. are discussed. A comparison is made with the Sarcoplasmic Reticulum system where calcium flux are easily measured. The latest results reviewed on intact cellular structures are highly indicative but not yet conclusive.
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    Calcium ion, a putative intracellular messenger for light-adaptation in Limulus ventral photoreceptors (1977)
    Springer
    European biophysics journal 3 (1977), S. 141-143 
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    ISSN: 1432-1017
    Keywords: Calcium ; Limulus ; Photoreceptors ; Adaptation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
    Notes: Abstract Calcium ion fulfills several criteria for identifying an intracellular messenger for light-adaptation in Limulus photoreceptors. Direct injection of Ca++ mimicks two aspects of light-adaptation; sequestration of intracellular calcium tends to prevent light-adaptation; and light induces an increase in intracellular Ca++ as demonstrated by two independent techniques.
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    On the mechanism of conductance control of the arthropod visual cell membrane (1977)
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    European biophysics journal 3 (1977), S. 145-151 
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    ISSN: 1432-1017
    Keywords: Visual cell membranes ; Invertebrates ; Ion channels ; Activation of light channels ; Calcium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
    Notes: Abstract It is assumed that “dark channels” determine a permanent dark conductance of the arthropod visual cell membrane. The light stimulus causes a transient opening of “light channels”. The ion selectivity of dark channels and light channels is roughly described. Factors influencing the activation of light channels, as membrane energy metabolism, membrane potential and adjusted calcium ion concentration are specified. The mechanism of the action of calcium ions on the conductance of the visual cell membrane is discussed.
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    Electron microscopic investigation of the hydrogen-oxidizing acetate-forming anaerobic bacterium Acetobacterium woodii (1977)
    Springer
    Archives of microbiology 115 (1977), S. 207-213 
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    ISSN: 1432-072X
    Keywords: Acetobacterium woodii ; Hydrogen-oxidizing acetate-forming anaerobe ; Fine structure ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Acetobacterium woodii is a Gram-positive anaerobic nonsporeforming bacterium able to grow on H2 and CO2 as sole sources of energy. The product of fermentation is acetic acid. Fine structural analysis showed rod-shaped flagellated cells, and coccoid cells without flagella arranged predominantly in pairs and chains. The cell wall was found to be composed of three layers. The cell surface exhibited a periodic array of particles consisting of subunits. The cytoplasmic membrane showed particles either either in random distribution or in a hexagonal pattern. Intracytoplasmic membranes were rarely observed, whereas inclusion bodies of varying shapes, predominantly in an uncommon disc-shape, could frequently be observed. Their content was dissolved in ultrathin sections indicating hydrophobic nature.
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    The ultrastructure of an olfactory sensillum on the maxillary palps of Locusta migratoria (L.) (1977)
    Springer
    Cell & tissue research 184 (1977), S. 397-409 
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    ISSN: 1432-0878
    Keywords: Chemoreceptor ; Olfaction ; Locusta ; Fine structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The olfactory sensilla on the maxillary palp tip of Locusta migratoria (L.) resemble the surrounding contact chemoreceptors in general morphology. The perforated peg has a thicker wall than is commonly found in olfactory sensilla. The form and position of the sensilla are considered in relation of the olfactory function. The fine structure of the dendrites is discussed in relation to that described in other olfactory sensilla.
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    Fine structure of the drum muscles of the piranha (serrasalminae, characidae) (1977)
    Springer
    Cell & tissue research 185 (1977), S. 547-555 
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    ISSN: 1432-0878
    Keywords: Drum muscles ; Fine structure ; Piranha
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The anterior and the posterior drum muscles of the piranha resemble each other in all essential fine structural aspects: myofibrils are slender; sarcomeres are short compared with those of other drum muscles; mitochondria, located in the periphery of the fibers, are numerous and show an irregular internal structure; and the sarcoplasmic reticulum is abundant. Triads appear at the level of the Z lines. The drum muscles have many motor endplates, which, however, lack the characteristic junctional-fold apparatus. No lipid substances could be demonstrated in these muscles. In the posterior drum muscle the fibers depart from their orderly longitudinal arrangement at irregular intervals.
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    The sarcoplasmic reticulum and associated plasma membrane of trunk muscle lamellae in Branchiostoma lanceolatum (Pallas) (1977)
    Springer
    Cell & tissue research 181 (1977), S. 169-196 
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    ISSN: 1432-0878
    Keywords: Skeletal muscle ; Branchiostoma lanceolatum ; Fibre types ; Sarcoplasmic reticulum ; Sarcolemma ; Calcium ; X-ray micro-analysis ; Freeze-fracturing ; Replica
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The trunk muscle lamellae of Amphioxus is made up of cross-striated lamellae about 1 μm thick. Transverse tubules are absent, but numerous subsarcolemmal vesicles are found in both tissue blocks and minced samples after aldehyde and osmium fixation, embedding and sectioning. The vesicles contain a granular matrix, range in diameter from 30 to 200 nm and constitute about 3 to 6% of the muscle fibre volume. 8 out of 10 vesicles are found above the Z and I-bands. In the presence of oxalate, electron dense precipitates form within the vesicles. Energy-dispersive X-ray microanalysis reveals the presence of Calcium in these precipitates. The area of the plasma membrane is about 2 μm2/μm3 muscle fibre volume. The corresponding area of sarcoplasmic membrane is ca. 1 μm2/μm3. About 20% of the plasma membrane is directly overlaid and coupled to the sarcoplasmic vesicles. A thin surface coat is present all over the lamellae, but ruthenium red staining indicates that the coat is slightly concentrated above the sarcoplasmic vesicles. Freeze-fracture replicas reveal tightly packed coarse granular material in the vesicular membrane and less concentrated and smaller particles in the plasma membrane. The latter particles are seen somewhat less commonly above the vesicles than on the rest of the plasma membrane. Likewise, direct replicas of lamella spread on glass slides and freeze-dried, reveal a distinct pattern in the surface coat or its underlying structures, corresponding to the Z and I-bands. In the scanning electron microscope the general arrangement of the sarcoplasmic vesicles could be examined. In addition, numerous defects in the plasma- and vesicular membranes indicate a strong adhesion between the two. It is concluded that the trunk muscle lamellae of Amphioxus have a sarcoplasmic reticulum consisting of subsarcolemmal vesicles with calcium sequestrating properties at Z and I-level. Further that the plasma membrane and its surface coat is probably specialized above the vesicles as compared to the rest of the surface.
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    The fine structure of Micrococcus radiophilus and Micrococcus radioproteolyticus (1976)
    Springer
    Archives of microbiology 107 (1976), S. 313-320 
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    ISSN: 1432-072X
    Keywords: Micrococcus radiophilus ; Micrococcus radioproteolyticus ; Bacterial cell walls ; Fine structure ; Electron microscopy ; Taxonomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The radiation resistant bacteria Micrococcus radiophilus and M. radioproteolyticus were studied by thin sectioning and freeze-etching techniques and the two species were found to be similar in the fine structure. The only significant difference was in the appearance of the surfaces of the cell walls in freeze-etched preparations. Since the two species, together with M. radiodurans, possess a unique cell wall structure and a cell wall peptidoglycan, which is different from that of other micrococci and Gram-positive cocci, it is recommended that they be reclassified into a new genus.
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    The fine structure of a microplate-microtubule array, microfilaments and polyhedral body associated microtubules in several species of Anabaena (1976)
    Springer
    Archives of microbiology 111 (1976), S. 1-6 
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    ISSN: 1432-072X
    Keywords: Microtubules ; Anabaena ; Microtilaments ; Microplate-microtubule array ; Fine structure ; Blue-green algae
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A microplate-microtubule array was observed in Anabaena sp. (B-378). This structure consists of an arched plate, about 8 nm thick, and various microtubules, 12 nm in diameter and 50 nm long, arranged in rows. The microtubules project at right angles from one side of the plate into the cytoplasm or towards the plasma membrane. Up to twelve microplate-microtubule arrays were observed in a single section of a cell. Microfilaments, about 2.8 nm in diameter and of undetermined length, were observed in four isolates of Anabaena. The microfilaments were always found in bundles, which varied in size, up to 0.63 μm across and 0.91 μ long. Microtubules, 10 nm in diameter and about 150 nm in length, were observed associated with one facet of polyhedral bodies in 8 out of 20 isolates of Anabaena. The microtubules occurred in groups of up to 20 or more, and were always oriented with the long axis parallel to a facet of a polyhedral body. In cross section, the microtubules had an electron transparent lumen 5 nm wide and a wall 2.5 nm thick. These structures are compared to previously deseribed microtubules and microfilaments.
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    Electron microscopic study on the gill bars of amphioxus (Brachiostoma californiense) with special reference to Neurociliary control (1976)
    Springer
    Cell & tissue research 166 (1976), S. 167-178 
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    ISSN: 1432-0878
    Keywords: Gill bars ; Fine structure ; Neurociliary control ; Neurosecretion ; Cephalochordata
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Both primary and secondary (tongue) bars of the pharyngeal gill basket are covered by epithelial cells that are continuous with the cells that line the atrium. Anterior and posterior faces of the gill bars are covered with lateral ciliated cells, which possess a single cilium, ringed by microvilli, and an elaborate basal mitochondria-rootlet apparatus. Pharyngeal faces of the gill bars are covered with ciliated pharyngeal cells, atrial faces by mucus secreting atrial cells. The surface epithelium rests on a stromal septum, a flattened tube of basal lamina which dilates to form the visceral blood vessel (along the pharyngeal face) and skeletal blood vessel (along the atrial face). This basal lamina surrounds paired skeletal rods which run through the longitudinal axis of the gill bars near the atrial face. Between the skeletal rods and atrial cells of primary gill bars is a coelomic channel lined by epithelioid coelomic cells. Neuronal processes, some with neurosecretory granules, are located among the bases of the atrial cells. Some axons may contact lateral ciliated cells where the latter meet atrial cells, but synaptoid endings have not been found here or elsewhere in the gill bars. Nervous tissue has not been identified among lateral ciliated cells even though ciliary activity of these cells is supposedly regulated by atrial nervous tissue.
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    Fine structure of chemosensitive cells (glomus caroticum) in tissue culture (1976)
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    Cell & tissue research 168 (1976), S. 55-63 
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    ISSN: 1432-0878
    Keywords: Glomus caroticum (rabbit) ; Primary tissue culture ; Dense-cored vesicles ; Fine structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Cells of the carotid body of both embryonic and 1 to 2-d-old rabbits were cultured in monolayer in primary tissue culture. The cells grew in their original association of type I and type II cells. The fine structure of both cell types was similar to that in vivo. Even after one week in culture their morphological characteristics, such as the dense-cored vesicles, were preserved. The prolonged synthesis of catecholamines in culture and the formation of new granular vesicles is discussed.
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    Fine structure of the fetal rat thyroid and parathyroid glands at term and during prolonged gestation (1976)
    Springer
    Cell & tissue research 166 (1976), S. 421-425 
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    ISSN: 1432-0878
    Keywords: Thyroid follicular and parafollicular cells ; Parathyroid cells ; Fetal rat ; Prolonged gestation ; Fine structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The fine structure of the fetal rat thyroid and parathyroid glands was studied at term and during prolonged gestation, which was induced by subcutaneous injections of progesterone to the mothers from gestational days 20 through 24. At term, the follicular and parafollicular cells of the thyroid as well as cells of the parathyroid exhibited well developed cytoplasmic organelles. Morphological changes were not detected in either of the endocrine glands during prolonged gestation. The results are discussed in relationship to 1) thyroid follicular cell activity during stress and 2) the function of thyroid parafollicular and parathyroid cells in calcium homeostasis.
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    The effects of starvation on the planarian worm Polycelis tenuis iijima (1976)
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    Cell & tissue research 169 (1976), S. 193-209 
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    ISSN: 1432-0878
    Keywords: Planaria ; Starvation ; Fine structure ; Biochemistry ; Cytochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Employing a combination of microscopical, biochemical and autoradiographic techniques, the primary effects of starvation on adult Polycelis tenuis have been studied. Over a five week period of starvation there is on average a 32% decrease in the size of the organism. This decrease is contributed to by a reduction in mitosis and an increase in cell shrinkage autolysis and death. During starvation (following a sharp rise in RNA synthesis) there is a distinct sequence of events; four peaks of acid phosphatase activity can be resolved. The first is associated with the immediate response of the gastrodermis to feeding; the second (after 6 to 7 days) with increased autophagy and dedifferentiation in the gland cells and with muscle lysis; the third peak (after 14 to 15 days) is contributed to largely by the lysis of cells in the gut and the fourth peak (after 25 to 26 days) is caused by an extensive lysis of the reproductive system. Fine structural changes involving increased intracellular vacuolation, autophagy, crinophagy, atrophy of muscle, increased intercellular space and loss of basement membrane matrix have been related to changes in enzyme pattern. Nerve cells appear unchanged throughout the first five weeks of starvation. Pigment and gland cells loose their characteristic granules, dedifferentiate and become morphologically similar to the undifferentiated neoblasts. Dedifferentiation and the mechanisms involved in the survival of starvation are discussed.
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    Effect of calcium depletion and subsequent repletion on parathyroids, parafollicular (C) cells and bone in the growing pig (1976)
    Springer
    Cell & tissue research 168 (1976), S. 373-384 
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    ISSN: 1432-0878
    Keywords: Calcium ; Bone ; Parathyroid ; Parafollicular cells ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The ultrastructure of the chief cells of the parathyroid gland and thyroid parafollicular (C) cells and the morphology of bone in calcium depletion and subsequent repletion were examined in young growing pigs. A low calcium diet resulted in osteopenia, increased removal of the cartilaginous core, osteoclasia and osteocytic osteolysis. Subsequent repletion quickly returned bone to normal. In pigs fed the low calcium diet, there was a marked depletion of secretory granules but a striking increase in the number of microtubules in chief cells. Increasing the calcium content of the diet to normal quickly returned the ultrastructural appearance of chief cells to apparent normal. In the initial response to calcium repletion, chief cells exhibited large number of lysosomes and occasionally prominent paracrystalloid bodies. Electron microscopic examination of parafollicular (C) cells of the thyroid gland failed to reveal differences in ultrastructure between test and control pigs. These findings support the view that bone resorption following calcium deficiency may be the result of a secondary hyperparathyroidism rather than of calcium deficiency per se.
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    The subcellular localization of calcium in vertebrate smooth muscle: Calcium-containing and calcium-accumulating structures in muscle cells of mouse intestine (1976)
    Springer
    Cell & tissue research 169 (1976), S. 221-231 
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    ISSN: 1432-0878
    Keywords: Smooth muscle ; Calcium ; Sarcoplasmic reticulum ; Mitochondria ; Microprobe analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The intracellular localization of calcium by means of cytochemical techniques was studied in smooth muscle cells of mouse intestine. When the lead acetate method according to Carasso and Favard (1966) was used calcium was found in mitochondria and sarcoplasmic reticulum and occasionally between the myofilaments. The active ATP-dependent accumulation of calcium into cell structures was investigated by the oxalate method (Heumann and Zebe, 1967). After appropriate treatment the only structures of smooth muscle cells which contained calcium oxalate (identified by microprobe analysis) were elements of the sarcoplasmic reticulum. The results are discussed in relation to the role of calcium in the control of muscle activity during the contraction-relaxation cycle.
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    Fine structure of the ocellus of the cabbage looper moth (Trichoplusia ni) (1976)
    Springer
    Cell & tissue research 171 (1976), S. 523-533 
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    ISSN: 1432-0878
    Keywords: Dorsal ocellus ; Cabbage looper moth ; Fine structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The dorsal ocelli of adult cabbage looper moths were studied by light microscopy, and scanning and transmission electron microscopy. Each ocellus has a cuticular lens located on the distal end of a cuticular cone which encapsulates the receptor cells. There are two distinct types of receptor cells in the ocellus. Seventy large receptor cells form plate-like rhabdoms with several adjacent cells to produce a rhabdom network in the ocellus. Proximally ninety small receptor cells which have a disorganized microvillar rhabdomere are located at the base of the rhabdoms formed by the large cells. Extensive areas of gap junctions which occur between the rhabdoms and the membranes of large and small cells suggest that the cells may be electrically coupled to one another. Axons from both large and small receptor cells leave the base of the ocellus and extend to the protocerebrum to synapse with second order neurons.
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    Effect of collagenase on mechanical activity and fine structure of an intestinal smooth muscle (1976)
    Springer
    Cell & tissue research 173 (1976), S. 29-44 
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    ISSN: 1432-0878
    Keywords: Smooth muscle ; Taenia coli ; Collagenase ; Fine structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The effect of the enzyme collagenase (40–200 units · ml-1) on the spontaneous mechanical activity in vitro and on the fine structure of the taenia coli of the guinea-pig was investigated. Initially, the spontaneous activity of the taenia was enhanced both in the isometric and isotonic recordings; after several minutes the muscles became slack or elongated to up to twice their resting lengths. The structural changes were dramatic but a number of muscle cells remained apparently unaltered even with the highest concentration and the longest incubation time (120 minutes). The large variety of structural changes were tentatively grouped into two separate sequences. One sequence involved swelling of the muscle cell, dispersion of the filaments and breaking up of the cell membrane: the thick myofilaments increased considerably in size and became heterogeneous in size and shape, but were still recognizable after disruption of the cell membrane. The other disruptive sequence involved separation of the superficial part of the muscle cell, which became electron-lucent, from the core of the cell where filaments were very densely packed. Few or no changes were observed in non-muscle cells.
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    The effect of the ionophore A23187 on the ultrastructure and electrophysiological properties of frog skeletal muscle (1976)
    Springer
    Cell & tissue research 173 (1976), S. 193-209 
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    ISSN: 1432-0878
    Keywords: Muscle ; Ionophore A23187 ; Calcium ; Muscular dystrophy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The divalent cation ionophore A23187 has three major effects on the thin cutaneous pectoris muscle of frog: (1) The membrane potential is depolarized, an action that is found only when the [Ca2+] of the bathing saline is very low. (2) It causes an increase in resting tension and the development of contraction. This action is produced at both normal and low values of [Ca2+]o and is, therefore, independent of Ca2+ entry and of changes in Em. The ionophore is believed to act primarily by releasing Ca2+ from intracellular stores. (3) It causes major ultrastructural damage to the muscle filaments. It is believed that this damage is the result of the action of A23187 on the sarcoplasmic reticulum and the elevation of [Ca2+]i and we suggest that the action of this ionophore may serve as a useful model for the study of certain myopathies.
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    The fine structure of the drum muscles of the Tigerfish, Therapon jarbua, as compared with the trunk musculature (1976)
    Springer
    Cell & tissue research 174 (1976), S. 453-463 
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    ISSN: 1432-0878
    Keywords: Drum muscles ; Therapon jarbua ; Fine structure ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The fibers of drum and trunk muscles of the Tigerfish, Therapon jarbua, differ greatly in diameter. The myofibrils of the trunk muscles are irregularly oriented, while those of the drum muscles are rolled into spiral or concentric bands. Both muscle types possess the sarcomere structure typical of cross-striated musculature. However, the myofibrils of the drum muscles differ greatly in sarcomere length and width from those in the trunk musculature. The trunk muscles contain few mitochondria, whereas in the drum muscles mitochondria are abundant. The sarcoplasmic reticulum (SR) of the drum muscles takes the form of elongated tubes in both the A and the I region; that of the trunk musculature consists of small vesicles. Of the two muscle types, the drum muscle contains more SR. With respect to the form of the T system, the trunk musculature is of the Z type and the drum muscles of the A-I type. The drum muscle displays a considerably greater number of motor endplates; these lack typical junctional folds and have mitochondria with very few cristae. No fat could be demonstrated in either the drum or the trunk muscles. However, the concentration of glycogen is higher in the drum muscle than in the musculature of the trunk.
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    The fine structure of polychaete septate junctions (1976)
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    Cell & tissue research 174 (1976), S. 55-67 
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    ISSN: 1432-0878
    Keywords: Septate junctions ; Polychaeta ; Fine structure ; Cell junctions ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Epidermal septate junctions of Nereis sp. and Cirriformia sp. fixed with OsO4 or glutaraldehyde/OsO4 display variable structure in electron micrographs. In transverse section the septa are often indistinct and obscured by opaque material that fills the junctional cleft. Septa (spaced at 180–280 Å) are more clearly defined in slightly oblique transverse section; they exhibit an electron lucent center and appear to be linked by arms. En face views of the junction show a honeycomb pattern. Cytoplasmic faces of junctional membranes are backed with plaques opposite the septa. Lanthanum used as a tracer delineates junctional structure in negative contrast. In transverse section a chain-like lattice is present in the junctional cleft. En face views show parallel rows of pleated elements often linked by arms into honeycomb arrays. Oblique sections demonstrate that these pleated elements are continuous with the chain-like lattice seen in transverse sections. Lanthanum does not pass entirely through the junction. Lanthanum reveals that the septa have a very intricate substructure, but it is difficult to visualize the architecture that could generate the various images presented by these junctions when seen in different orientations. However, it is clear that these junctions possess some features that are diagnostic of several supposedly different types of septate junctions in invertebrates.
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    Gloeomonas oderChlamydomonas? Elektronenmikroskopische Untersuchungen anGloeomonas simulans (1976)
    Springer
    Plant systematics and evolution 125 (1976), S. 109-121 
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    ISSN: 1615-6110
    Keywords: Chlorophyceae ; Volvocales ; Gloeomonas ; Chlamydomonas ; Fine structure ; flagellar rootlet system ; cell wall ; nuclear inclusions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The fine structure ofGloeomonas simulans Fott (1957) was studied electron microscopically to ascertain whether it belongs to the genusChlamydomonas rather than toGloeomonas. Most cytoplasmic elements and the cell wall do not differ from otherChlamydomonadaceae but its flagellar rootlet system is unique: Each of the two flagella has an accessory basal body; its basis is accompanied by two inner and two outer bands which are connected distally (one inner and one outer band on each side) resp. proximally (the two outer bands); the latter form a long (up to 3–5 µm) connecting band between the two flagellar bases. The nucleus contains fibrillar bundels.—The unique flagellar rootlet system seems to provide a better basis for the generic classification ofGloeomonas than the position of the contractile vacuoles or the size of the apical papilla, and strongly suggests the exclusion ofG. simulans fromChlamydomonas.
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    Ultrastructural evidence for a direct connection between the myocardial granules and the sarcoplasmic reticulum in the cardiac ventricle of Myxine glutinosa (L.) (1975)
    Springer
    Cell & tissue research 163 (1975), S. 353-363 
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    ISSN: 1432-0878
    Keywords: Specific heart granules (Cyclostome) ; Atrial granules ; Calcium ; Uranophilic core substance ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The occurrence of structural connections between myocardial granules and tubular elements of the sarcoplasmic reticulum in the cardiac ventricle of the Atlantic hagfish is described. The core substance of the myocardial granules is shown to be uranophilic and in this respect similar to the granular cores within the lumen of the sarcoplasmic reticulum. After application of CaCl2-containing fixatives, the ultrastructure of the core substance of these organelles resembles that described for calcium-containing structures in vertebrate glial cells. Incidences of uranophilic core substance in the extracellular space suggest a secretory function of the myocardial granules. Possible implications of the sarcoplasmic reticulum and the myocardial granules in storage, intracellular transport, and secretion of bound calcium are discussed.
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    Chloride cells of larval Notonecta glauca and Naucoris cimicoides (Hemiptera, Hydrocorisae) (1975)
    Springer
    Cell & tissue research 156 (1975), S. 539-549 
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    ISSN: 1432-0878
    Keywords: Chloride cells ; Waterbugs (Notonecta glauca, Naucoris cimicoides) ; Fine structure ; Osmoregulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The chloride cells of the larval waterbugs, Notonecta glauca L. and Naucoris cimicoides L., ultrastructurally resemble the caviform chloride cells of other aquatic insects as well as those of teleost fish. Their predominant features are abundant mitochondria, basolateral plasma membrane infoldings and an apical cavity possessing numerous microvilli. After histochemical precipitation of chloride, dense deposits of silver chloride are present in the apical region. The cuticular area overlying the chloride cells is extremely reduced in thickness and differentiated into a plug-like structure. The 1st instars of Notonecta glauca raised from the eggs at various hypo-osmotic salt concentrations have identical numbers of thoracal chloride cells regardless of the external salinity. The number of cells progressively increases with each moult. However, in corresponding larval stages, there is a significant decrease in the number of thoracal chloride cells relative to increases in the external salinity. These results are consistent with the presumptive involvement of the chloride cells in osmotic hyperregulation.
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    Spermatogenesis in anthozoa: Differentiation of the spermatid (1975)
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    Cell & tissue research 157 (1975), S. 185-205 
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    ISSN: 1432-0878
    Keywords: Spermatids ; Fine structure ; Spermiogenesis ; Anthozoa
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The fine structure of spermatids has been examined in Calliactis, Protanthea, Gonactinia and Parazoanthus (Cnidaria, Anthozoa). The sperm cells are relatively simple and lack distinct acrosomes. Their nuclei, spherical in the zoanthid, in the actinians are slendertipped cones. Condensation of the chromatin is interpreted in terms of progressive coiling of densely-stained filaments and the elimination of nucleoplasm. Nuclear elongation occurs in the absence of microtubules. A well-developed centriolar complex is attached to the nuclear envelope by fibres and in this area (that of a shallow fossa in actinian sperm) the nuclear membranes seem to be thickened. The centrioles are surrounded by a mitochondrial collar, especially pronounced in Calliactis. In contact with the mitochondria and nucleus is a ring of lipid-containing vesicles 300–700 nm in diameter. A system of densely-staining vesicles 150–300 nm in size corresponds to the “pro-acrosomal vesicles” described for other coelenterates. They are scattered in the peripheral cytoplasm and are regarded as derivatives of the endoplasmic reticulum. Problems of organelle function and of differentiation during spermiogenesis are discussed.
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    The distribution of oxidizable mucosubstances and polysaccharides in the planarian Polycelis tenuis iijima (1975)
    Springer
    Cell & tissue research 161 (1975), S. 263-275 
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    ISSN: 1432-0878
    Keywords: Oxidizable mucosubstances ; Fine structure ; Planaria ; X-ray microanalysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary A chromic acid oxidation-silver technique was used to localize polysaccharide material in Polycelis tenuis at the electron microscope level. In the epithelium, staining was observed within apical vacuoles and on the free surfaces of the cells. A similar staining was observed in relation to the glycocalyx of the pharyngeal epithelia and that of the flame cells. Silver was deposited in the basement membrane. In the parenchyma, the major components giving a positive reaction were the cyanophil and mucous gland cells. Particularly strong silver staining (confirmed by X-ray microanalysis) was observed in the granules and Golgi apparatus of the cyanophil cells. IDPase activity was also found in relation to the Golgi apparatus and its secretory products. The overall distribution of mucopolysaccharide material was confirmed with the PAS and Alcian blue techniques. The fine structural localization of the Alcian blue was also determined using electron microscopy and X-ray microanalysis.
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    Additional evidence for the binding of calcium ions to elastin at neutral sites (1974)
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    Calcified tissue international 14 (1974), S. 317-325 
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    ISSN: 1432-0827
    Keywords: Calcification ; Neutral sites ; Elastin ; Calcium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé Des études précédentes suggèrent la présence de groupements carboxyles, sulfhydriles et aminés dans les sites de liaison en calcium de l'élastine. La possibilité de l'existence de sites neutres de liaison en calcium au niveau de l'élastine a été étudiée dans ce travail. Une augmentation de la fixation du calcium au niveau de l'élastine est observée après des modifications de dissolution qui ont aussi provoqué des modifications de structure de la protéine. Dans des mélanges méthanol-H2O, les liaisons du calcium semblent indépendantes du pH et de la force ionique. Sur dix ions testés (Ca2+, CO2+, Na2+, Cu2+, Zn2+, Cr3+, Pb+2, K+, Rb+ et Mg2+) seule la liaison du calcium est nettement augmentée, lorsque le méthanol est ajouté. Il semble que les sites neutres sont importants pour les divers rapports entre calcium et élastine et servent, peut-être, comme centres de nucléation au cours de la calcification de la protéine.
    Abstract: Zusammenfassung Vorgängige Studien haben die Bedeutung der Carboxyl-, Sulfhydryl- und Aminogruppen als Stellen der Calciumbindung im Elastin gezeigt. Die vorliegende Arbeit hatte zum Ziel, die Rolle der neutralen Koordinationsstellen im Elastin als mögliche Calcium-Bindungsseite abzuklären. Die Calciumbindindung an das Elastin wurde durch solche Lösungsmittelveränderungen erhöht, die auch gleichartige Verschiebungen im Proteinmolekül bewirkten. In Methanol-Wasser-Mischungen schien die Calciumbindung nicht von Veränderungen des pH oder der Ionenstärke abhängig zu sein. Von 10 Ionen, bei welchen die Bindung überprüft wurde, war einzig diejenige des Calciums signifikant erhöht, wenn Methanol zugesetzt wurde. Es wird vorgeschlagen, daß die neutralen Stellen für die verschiedenen Vorgänge, bei welchen Calcium und Elastin beteiligt sind, eine wichtige Rolle spielen und vielleicht für die Verkalkung der Proteine als Nukleationszentren in Frage kommen.
    Notes: Abstract Previous studies have implicated carboxyl groups, sulphhydryl groups and amino groups as the sites for calcium binding in elastin. In this study, the concept was investigated that neutral co-ordinating sites in elastin may also provide calcium binding sites. Calcium binding to elastin was increased upon solvent changes which also effected conformational changes in the protein. In methanol-H2O mixtures calcium binding appeared to be independent of changes in pH and ionic strength. Of ten ions tested (Ca2+, Co2+, Na+, Cu2+, Zn2+, Cr3+, Pb+2, K+, Rb+, and Mg2+), only calcium binding was significantly increased when methanol was added. It is proposed that neutral sites are important to the various relationships involving calcium and elastin and perhaps serve as nucleation centers in the calcification of the protein.
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    The effects of vitamin D analogues on bone resorption (1974)
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    Calcified tissue international 15 (1974), S. 333-339 
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    ISSN: 1432-0827
    Keywords: Vitamin D ; Bone ; Resorption ; Calcium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract A series of analogues of vitamin D have been tested for their ability to stimulate bone resorption in two test systems used previously to investigate the metabolites of vitamine D. These analogues were tested (a) by directly comparing their action on bone explants of mouse half-calvariain vitro, and (b) by injecting them into young mice and measuring the degree of resorptionin vitro when explants were prepared 18 hours after the injection. It is concluded that the key functional groups concerned with enhancing the activity of vitamin D3 are the 1α- and the 25-hydroxyl,both together; the cis ring structure for ring A appears necessary. 1α-Hydroxycholecalciferol (1α-OHD3) is about as active as 25-OHD3 in the direct test, but its potency is much nearer to that of 1,25-(OH)2D3 when tested by the second (indirect) method; it seems likely that 1α-OHD3 is converted into 1,25-(OH)2D3 in vivo. The results are discussed in relation to the designing of analogues for clinical and experimental use.
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    Effect of age on bone calcium and phosphate metabolism in organ culture (1974)
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    Calcified tissue international 16 (1974), S. 89-92 
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    ISSN: 1432-0827
    Keywords: Age ; Bone culture ; Calcium ; Phosphate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract Calvaria taken from mice aged 0, 1, 3 and 5 days were cultured for 48 h, in control medium (no added hormone), or in the presence of PTH (0.5 U/ml) or CT (50 mCl/ml). In the control group, there was a shift from net uptake of Ca and P (0- and 1-day bones) to net release (5-day bones). CT-treated bones of all ages took up Ca from the culture medium, but the percentage uptake declined with increasing age. Bones exposed to PTH released Ca and P to the culture medium, regardless of age. The changes with increasing age may be related to an increase in mineralization and other aspects of maturation in these bones.
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    Serum calcium, phosphate and alkaline phosphatase and morphometric bone examinations in 30 patients with renal insufficiency (1974)
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    Calcified tissue international 16 (1974), S. 129-138 
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    ISSN: 1432-0827
    Keywords: Serum ; Calcium ; Phosphate ; Alkaline phosphatase ; Kidney
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract In 30 patients with chronic renal insufficiency (16 non-dialysed and 14 on dialysis) serum calcium, phosphate and alkaline phosphatase were determined and, in a crest biopsy specimen, morphometric determinations of bone qualities were calculated. A positive correlation was established between serum alkaline phosphatase, the osteoblast surface and the active resorption surface in both dialysed and non-dialysed patients. A positive correlation was also established between the osteoblast surface and the active resorption. In the non-dialysed patients a negative correlation was established between serum calcium and the osteoid surface.
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    Effects ofSolanum malacoxylon on embryonic bonein vitro and on isolated mitochondria (1974)
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    Calcified tissue international 16 (1974), S. 219-226 
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    ISSN: 1432-0827
    Keywords: Bone ; Phosphate ; ATP ; Calcium ; Mitochondria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract An active constituent of the leaves ofSolanum malacoxylon (SM) is shown to promote calcium resorption and citrate production in embryonic chick frontal bone culturedin vitro. When injected into rats, SM reduces the ATP content of liver and kidneys. This phenomenon may be related to the ability of SM to stimulate mitochondrial ATPase activity at pH 9.4. SM significantly reduces the concentration of phosphate necessary to alter the uptake of calcium and respiration of siolated mitochondria. The data suggest that SM influences calcium and phosphate metabolism by affecting ion movements into and out of mitochondria.
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    Effects of ethylenediaminetetraacetate (EDTA) on urinary excretion of hydroxyproline, calcium and phosphorus in the rat (1974)
    Springer
    Calcified tissue international 16 (1974), S. 1-12 
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    ISSN: 1432-0827
    Keywords: EDTA ; Bone resorption ; Parathyroid hormone ; Calcium ; Hydroxyproline
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract The effects of ethylenediaminetetraacetate (EDTA) were studied in rats. Intravenous infusion of 4.84 mM Na2EDTA increased the urinary excretion of calcium six-fold, phosphorus three-fold and hydroxyproline 55% in 158 g thyroparathyroidectomized (TPTXed) rats. Calcitonin (25 MRC mU/rat/h) abolished the sodium EDTA-induced increase in hydroxyproline excretion, presumptive evidence that sodium EDTA was acting on bone. To determine whether the changes induced by sodium EDTA are due to lowering of plasma calcium, rats were infused with 4.84 mM ethylenebis(oxyethylenenitrilo)tetraacetic acid (EGTA), a more specific calcium chelator. EGTA increased the urinary excretion of calcium and phosphorus (P〈0.001) but not hydroxyproline in thyroparathyroidectomized rats. Furthermore, when TPTXed rats were infused with calcium EDTA (4.84 mM Ca2EDTA) in order that ionic calcium concentration would not be altered, hydroxyproline excretion was again markedly increased but phosphorus excretion was decreased by 26%. Since the displacement of the sodium ions in Na2EDTA by calciumin vivo is instantaneous, and since calcium EDTA itself induces collagenolysis, the increase in urinary hydroxyproline excretion due to sodium EDTA cannot be attributed solely to lowering of plasma calcium. From these data two conclusions are drawn. First, sodium EDTA enhances bone breakdown independently of its effect on parathyroid hormone secretion. Second, since bone plays a major role in the maintenance of plasma calcium, interpretation of results should be made with caution in those investigations in which EDTA is used to study calcium homeostasis.
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    Elemental composition of the superficial layer of rat incisor enamel (1974)
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    Calcified tissue international 16 (1974), S. 139-144 
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    ISSN: 1432-0827
    Keywords: Dental enamel ; Iron ; Calcium ; Phosphorus ; Electron probe
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract Using electron microprobe analysis, the surface layer of enamel of rat maxillary incisors was found to contain 10–30% Fe. The Ca and P concentrations in different areas of the enamel surface varied inversely with the Fe concentration. The Ca/P weight ratio was 1.8 in areas containing 10% Fe, but decreased to 1.0 in the most Fe-rich areas. The Fe concentration was highest at the prism boundaries, whereas the maximum concentrations of Ca and P were found within the enamel prisms. The concentrations of Fe in rat incisor enamel are among the highest values reported for any mineralized tissue.
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    The effect of thyroid hormone on calcium-induced nephrocalcinosis in the jird (Meriones unguiculatus) (1974)
    Springer
    Calcified tissue international 16 (1974), S. 157-162 
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    ISSN: 1432-0827
    Keywords: Hypothyroidism ; Hyperthyroidism ; Nephrocalcinosis ; Calcium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract Meriones unguiculatus (jirds or ‘gerbils’) were rendered hypo- or hyperthyroid by the addition of carbimazole or liothyronine to their diet, and in each of these states were found to be highly susceptible to the nephrotoxic effects of calcium gluconate. Histological studies showed that the pattern of induced nephrocalcinosis was the same in the hypo-, hyper- and eu-thyroid animals and was in the form of calcium deposits both within the cells of the proximal and distal convoluted tubules and in the basement membranes around such tubules. In view of these findings analysis of thyroid function should perhaps be incorporated into the list of diagnostic procedures used in the investigation of patients with nephrocalcinosis and nephrolithiasis.
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    Données histologiques et ultrastructurales sur le calcium thyroïdien (1974)
    Springer
    Calcified tissue international 14 (1974), S. 67-82 
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    ISSN: 1432-0827
    Keywords: Calcium ; Thyroïd ; Calcitonin ; Hibernation ; Electron microprobe
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé Une quantité importante de calcium se trouve conservée dans la thyroïde de Mammifères soumise à des traitements histologiques qui en eliminent la forme diffusible et les sels minéraux. Sur six espèces examinées, seul l'hibernantElyomis quercinus L. (Lérot) fait exception. Ce calcium, vraisemblablement engagé en combinaisons organiques, se répartit entre la colloïde, les cellules à calcitonine et les noyaux des deux lignées de cellules endocrines. Dans calcitonine, il revêt les grains de sécrétion d'une coque dense. Dans les noyaux, enfin, où sa teneur est très variable, il ne semble pas correspondre en totalité au cation habituellement lié aux acides nucléiques. Il existe, en outre, un calcium diffusible bien représenté dans les espaces intercellulaires et le long des lames basales. La forme diffusible se trouve aussi bien chez l'hibernant que dans les cinq autres espèces.
    Abstract: Zusammenfassung Nach routinemäßiger Aufarbeitung der Säugerschilddrüse für Histologie, bei welcher diffusionsfähiges Calcium und Mineralsalze eliminiert werden, bleiben erhebliche Mengen von Calcium erhalten. Von 6 untersuchten Arten ist der WinterschläferEliomys quercinus L. (Gartenschläfer) die einzige Ausnahme. Das vermutlich organisch gebundene Calcium verteilt sich auf das Kolloid, die Calcitoninzellen und die Zellkerne beider endokriner Zellstämme. Im Kolloid befindet es sich meist in den intrafollikulären Zellen; in den Calcitoninzellen umgibt es die Sekretkörner mit einer dichten Hülle; der Calciumgehalt der Zellkerne unterliegt großen Schwankungen und das Metall scheint nicht nur an die Nukleinsäuren gebunden zu sein. Ferner ist in der Schilddrüse diffusionsfähiges Calcium nachweisbar, das sich sowohl in den Interzellularräumen als auch entlang den Basalmembranen befindet; sowohl die Schilddrüse der winterschlafenden Art als auch die der anderen 5 Spezies enthalten Calcium in dieser Form.
    Notes: Abstract Large quantities of calcium are preserved in the thyroïd of Mammals after removal of the diffusible form and mineral salts by routine histological processes. Among the six species studies, only the hibernating species,Eliomys quercinus (garden dormouse), constitutes an exception. This calcium, probably bound organically, is localised in the colloïd, calcitonin cells and nuclei of both types of endocrine cells. In the colloïd, it is often associated with intrafollicular cells. In calcitonin cells, it densely coats the secretion granules. In nuclei, where the quantities of calcium vary greatly, it does not appear to correspond entirely to the cation usually associated with nuclei acids. Moreover, appreciable amounts of diffusible calcium are present in intercellular spaces and along basal laminae. This diffusible form exists in the hibernating species as well as in the five other species.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02060284
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    Effect of ethane-1-hydroxy-1,1-diphosphonate (EHDP) administration on duodenal calcium transport (1974)
    Springer
    Calcified tissue international 15 (1974), S. 21-29 
    Details
    ISSN: 1432-0827
    Keywords: EHDP ; Intestinal transport ; Calcium ; Vitamin D ; Microvilli
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé De l'éthane-1-hydroxy-1,1-diphosphonate (EHDP), administré par voie sous-cutanée à des rats à doses élevées (10 mg P/Kg de poids par jour×10), inhibe le transport du calcium au niveau du duodenum de rats, en utilisant des rapports de concentration serum/muqueuse en45Ca pour mesurer le transfert actif. Des études de microscopie électronique montrent l'accumulation de granules denses aux électrons dans les microvillosités: ces granules seraient constitués par une forme de calcium lié. On note aussi la rareté de ces granules dans les mitochondries; ces modifications sont analogues à celles observées dans les rats rachitiques. Il semble que les phénomènes pathologiques soient liées à un trouble du transport du calcium des microvillositées vers d'autres sites intracellulaires.
    Abstract: Zusammenfassung Es zeigte sich, daß bei Ratten, die mit hohen Dosen (10 mg P/kg Körpergewicht täglich×10) von Aethan-1-hydroxy-1,1-diphosphonat (EHDP) subkutan behandelt wurden, der Calciumtransport im Duodenum (gut sacs) gehemmt wurde; zur Messung des aktiven Transportes wurde das45Ca-Konzentrationsverhältnis Serosa/Mucosa benützt. Elektronenmikroskopische Untersuchungen zeigten in den Microvilli eine Anhäufung von elektronendichten Granula, die eine gebundene Form von Calcium darstellen; eine kleine Anzahl solcher Granula fand sich in den Mitochondrien; diese Veränderungen können auch bei rachitischen Ratten beobachtet werden. Aus den Resultaten kann geschlossen werden, daß dieser Defekt teilweise durch eine Interferenz des Calciumtransportes von den Microvilli zu anderen intrazellulären Stellen bedingt ist.
    Notes: Abstract Ethane-1-hydroxy-1,1-diphosphonate (EHDP) given subcutaneously to rats in high doses (10 mg P/Kg body weight daily×10) inhibited the transport of calcium by rat duodenal gut sacs, when45Ca serosal/mucosal concentration ratios were used to measure active transport. Electron microscopic studies revealed the accumulation of electron-dense granules in the microvilli, representing a bound form of calcium and a paucity of such granules in mitochondria, changes identical to those seen in rachitic rats. These results suggest that the defect is mediated in part by interference in transport of calcium from microvilli to other intracellular sites.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02059040
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  • 92
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    Structure of long bones of rats and mice fed a low calcium diet (1974)
    Springer
    Calcified tissue international 15 (1974), S. 71-76 
    Details
    ISSN: 1432-0827
    Keywords: Bone ; Calcium ; Deficiency ; Osteoporosis ; Species
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract 21-day-old rats and mice were fed a low-calcium diet (0.02% Ca) or a normal diet (0.5% Ca) for two weeks. Administration of the low-calcium diet resulted in greater decreases in femur ash content and serum calcium in rats than in mice. Microscopic examination revealed that metatarsal bones from a majority of the rats fed a low-calcium diet displayed moderate or severe osteoporotic changes whereas bones from mice were either normal or displayed only slight osteoporotic changes under the same experimental conditions. These results indicate that mice are better able to adapt to a low-calcium diet than are rats of the same age.
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    URL: http://dx.doi.org/10.1007/BF02059044
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  • 93
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    Characteristics of calcium uptake by calcitonin-treated mouse calvariain vitro (1974)
    Springer
    Calcified tissue international 15 (1974), S. 85-92 
    Details
    ISSN: 1432-0827
    Keywords: Calcitonin ; Calcium ; Uptake ; bone culture
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract The effect of calcitonin (CT) on calcium metabolism by bone was investigated in a stationary organ culture system, using half-calvaria from 5-day-old mice. CT induced the uptake of calcium by bones from the culture medium. This uptake was not accompanied by phosphate, so that the final Ca:P ratio of CT-treated bones (1.80±0.06) was significantly (p〈0.02) higher than the initial values before culture (1.59±0.03). The calcium uptake reached a plateau after approximately 48 hours of culture, and was reversed by PTH within 48 hours. Calcium uptake rppears to be an active effect of CT, and cannot be explained fully by an inhibition of bone aesorption, stimulation of new bone formation, or maturation of the mineral phase.
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    URL: http://dx.doi.org/10.1007/BF02059047
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  • 94
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    Effect of fluoride, calcium and phosphorus on periosteal surfaces (1974)
    Springer
    Calcified tissue international 15 (1974), S. 111-123 
    Details
    ISSN: 1432-0827
    Keywords: Fluoride ; Calcium ; Phosphorus ; Bone ; Periosteum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé Une méthode d'estimation de la surface périostée de l'os en voie de minéralisation est mise au point et appliquée à des porcs recevant 2 mg de fluorure par Kg de poids et par jour pendant 10 mois. L'adjonction de fluor intervient significativement dans le cas d'une déficience en calcium et phosphore. La surface en voie de minéralisation est nettement réduite. Lorsque le calcium et phosphore sont normaux, l'addition de fluorure augmente nettement la surface en voie de minéralisation. Le microscope électronique à balayage permet de mettre en évidence au niveau de l'os une perte de l'orientation longitudinale des fibers et des surfaces poreuses irrégulières chez les animaux soumis au floor.
    Abstract: Zusammenfassung Zur Bestimmung der verkalkenden Oberfläche des Periosts wurde eine Methode entwickelt und bei Schweinen angewandt, welche während etwa 10 Monaten 2 mg Fluorid per kg Körpergewicht und per Tag erhalten hatten. Dieses zusätzliche Fluorid hatte eine signifikante Wirkung bei Calcium- und Phosphormangel. Die verkalkende Oberfläuche ging stark zurück, während jedoch, wenn kein Calcium- und Phosphormangel bestand, das zusätzliche Fluorid die verkalkende Oberfläche vergrößerte. Beobachtungen mit dem Raster-Elektronenmikroskop am Knochen zeigten, daß die Längsorientierung der Fasern fehlte und daß Knochen von mit Fluorid gefütterten Tieren unregelmäßige, poröse Oberflächen aufwiesen.
    Notes: Abstract A method for estimating periosteal bone-mineralizing surface was developed and applied to swine fed 2 mg of fluoride/kg of body weight/day for about 10 months. Added fluoride interacted significantly with calcium and phosphorus deficiency. Mineralizing surface was greatly reduced, whereas when calcium and phosphorus were adequate, added fluoride greatly increased mineralizing surface. Scanning electron microscope observations of bone disclosed loss of longitudinal orientation of fibers and irregular porous surfaces in bone from fluoride-fed animals.
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    URL: http://dx.doi.org/10.1007/BF02059049
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    Reproducibility of specific gravity estimations on bone samples from different sites of cattle and sheep (1974)
    Springer
    Calcified tissue international 15 (1974), S. 181-188 
    Details
    ISSN: 1432-0827
    Keywords: Biopsy ; Bone ; Calcium ; Phosphorus ; Specific gravity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract The specific gravities (SG) of bone samples taken from various parts of the skeleton of cattle and sheep were determined gravimetrically in an effort to establish which sites give the most reproducible and uniform results, so that between animals, or sequential within animals, comparisons may be made with maximum sensitivity. Samples obtained from the mandible of sheep and the rib of cattle and sheep were found to be too variable to be useful for most purposes. Best results were obtained using whole bones which are easily prepared, such as the tibial tarsal bones of cattle and sheep and the fibular tarsal bone of cattle. These bones gave within animal deviations of 0.012–0.024 SG units, when comparing left bone with right bone. Slightly higher values were obtained for coccygeal vertebrae from cattle and distal metacarpal condyles from sheep. SG was related to ash, calcium and phosphorus contents of coccygeal vertebrae of cattle and it is considered that, for survey work on the mineral status of the bones of cattle and sheep, the correlations are sufficiently high to make their determination unnecessary. This will enable radiation determined SG techniques to be applied to this type of work.
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    URL: http://dx.doi.org/10.1007/BF02059055
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  • 96
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    Inhibition of calcium phosphate crystallization by nucleoside phosphates (1974)
    Springer
    Calcified tissue international 15 (1974), S. 287-293 
    Details
    ISSN: 1432-0827
    Keywords: Calcium ; Phosphate ; Inhibition ; Crystallization ; Nucleotides
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The 5′-triphosphates of adenosine, guanosine, uridine, and cytidine inhibited the crystallization of calcium phosphate from stable supersaturated solutions that had been seeded with crystals of hydroxyapatite. Concentrations of the nucleoside triphosphates in the micromolar range were sufficient to have a significant effect on the crystal growth process. Diphosphate and monophosphate derivatives had less effect on the precipitation of calcium phosphate. It is possible that the nucleoside triphosphates may play a beneficial role in regulating intracellular calcification, particularly in disease states in which calcium entry into cells is pathologically high.
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    URL: http://dx.doi.org/10.1007/BF02059063
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    The effect of two diphosphonates on the handling of calcium by rat kidney mitochondriain vitro (1974)
    Springer
    Calcified tissue international 15 (1974), S. 303-314 
    Details
    ISSN: 1432-0827
    Keywords: Diphosphonates ; Calcium ; Mitochondria ; ATPase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract The effect of two diphosphonate compounds on calcium handling in rat kidney mitochondria has been studiedin vitro. Initial calcium uptake in the presence of an oxidisable substrate and ATP was not influenced by either diphosphonate tested. The release of accumulated calcium from the mitochondria was, however, delayed by these compounds and the effect was found to be dose dependent. Similarily, a second uptake of calcium, induced by re-addition of ATP following preliminary release, was also modified by diphosphonates, the mitochondrial suspensions incubated with diphosphonates accumulating more calcium than control suspensions. The effect of these compounds could not be detected on three mitochondrial ATPase systems. The results have been discussed in relation to knownin vivo effects of diphosphonates.
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    URL: http://dx.doi.org/10.1007/BF02059065
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  • 98
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    On the mechanism of shell mineral solubilization by the chick embryo (1974)
    Springer
    Calcified tissue international 16 (1974), S. 339-342 
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    ISSN: 1432-0827
    Keywords: Calcium ; Resorption ; Shell membrane ; Chick ; Chloride
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract A histochemical test for chloride was conducted on shell membranes from hen eggs incubated for 9 or 17 days. After fixation with a mixture of osmium tetroxide and silver nitrate and subsequent exposure to direct sunlight, the membranes showed an abundant coarse precipitate. This precipitate did not appear in sections treated with a solution of nitric acid indicating that it did not contain chloride. However, a small amount of fine acidresistant precipitate was detected by electron microscopy and probably contained chloride. The theory which defines hydrochloric acid as the main solubilizing agent of shell mineral is based on histochemical results which supposedly demonstrate large concentrations of chloride in the shell membrane and chorionic epithelium. The present results do not support these observations.
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    URL: http://dx.doi.org/10.1007/BF02008242
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  • 99
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    Studies on the formation of calcified egg-capsules of ampullarid snails (1974)
    Springer
    Calcified tissue international 16 (1974), S. 283-291 
    Details
    ISSN: 1432-0827
    Keywords: Snails ; Vaterite ; Calcium ; Storage
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract Large quantities of calcium carbonate crystals were present in the albumin gland of the reproductive system of the fresh-water snailPomacea paludosa. X-ray diffraction analyses indicated that they were vaterite. Scanning electron microscope observation of the albumin gland revealed that they occurred as spherules and were distributed throughout the gland. Vaterite spherules were present in the albumin gland ofPomacea urceus and the capsule gland ofPila virens. The mineral portion of the egg capsules was also vaterite. The egg capsule of these snails consisted of two morphologically distinct layers. Vaterite is less common in nature than the other two polymorphs of calcium carbonate, calcite and aragonite, and has not been recorded in the reproductive system of molluscs. It is interesting to note that in these snails calcium carbonate was present as vaterite both in the storage organ and fully differentiated egg capsule.
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    URL: http://dx.doi.org/10.1007/BF02008236
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  • 100
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    Fine structure of frog lime sacs (1974)
    Springer
    Cell & tissue research 148 (1974), S. 301-308 
    Details
    ISSN: 1432-0878
    Keywords: Fine structure ; Lime sacs ; Anura ; Calcium transport
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary A histochemical and electron microscopical study was conducted on the lime sacs of larval and adult Rana catesbiana. Both undecalcified and EDTA-decalcified material was analyzed. The follicles of the lime sacs contain numerous aragonite crystals and are lined by a cuboidal epithelium. The epithelial cells contain granules of a material identified histochemically as acid mucopolysaccharide. Crystals similar to those present in the lumen of the follicles were also found inside the epithelial cells. These cells possess nuclei with coarsely distributed chromatin, many mitochondria, free ribosomes, well developed Golgi complexes and a few profiles of rough endoplasmic reticulum. Numerous variously electron dense granules seem to correspond to those characterized histochemically as mucopolysaccharides. Large, intracellular vacuoles appear to contain crystals. Release of the crystals into the lumen seems to occur by apocrine secretion. Resorption of calcium from the lumen probably takes place by diffusion through the apical plasma membrane as indicated by the presence of numerous microvilli. The intercellular spaces contain numerous, thin, interdigitating processes from neighbouring cells and appear to be sealed at both ends by junctional complexes. This observation is discussed in relation to the idea that the intercellular spaces might be related to the transit of calcium from the epithelial cells towards the sub-epithelial capillaries.
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    URL: http://dx.doi.org/10.1007/BF00224258
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