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  • Calcium  (137)
  • Neurosecretion  (90)
  • Fluoride
  • Springer  (243)
  • MDPI Publishing
  • National Academy of Sciences
  • 1975-1979  (85)
  • 1970-1974  (134)
  • 1965-1969  (24)
  • 1935-1939
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  • Springer  (243)
  • MDPI Publishing
  • National Academy of Sciences
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  • 1
    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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  • 2
    Electronic Resource
    Electronic Resource
    Bone fluoride concentrations associated with fluoridated drinking water (1979)
    Springer
    Calcified tissue international 27 (1979), S. 95-99 
    Details
    ISSN: 1432-0827
    Keywords: Bone ; Fluoride ; Analysis ; Food ; Age
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Recently published bone fluoride values from Iowa are very high compared to earlier reports, suggesting an increase in fluoride intake. Reanalysis of the Iowa specimens shows levels one-fourth those reported by the Iowa laboratory indicating an error in the original report. Seventeen bone specimens, collected from long-term residents of Rochester, New York, drinking 1 ppm F− water, had a mean value of 2085±270 ppm F− on an ashed-weight basis. This value is not significantly different from that predicted by the data of Zipkin et al. in 1958. These data, therefore, do not support the contention that there has been an increase in fluoride intake.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02441168
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  • 3
    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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  • 4
    Electronic Resource
    Electronic Resource
    Comparative uptake of fluoride from sodium fluoride, ammonium fluoride, and barium fluoride in rat teeth when predominantly administered in the pre-eruptive stage of development (1979)
    Springer
    Calcified tissue international 27 (1979), S. 117-119 
    Details
    ISSN: 1432-0827
    Keywords: Pre-eruptive ; Systemic ; Deposition ; Absorbability ; Fluoride
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary A comparative study was undertaken which focused on the systemic uptake of sodium fluoride (NaF), ammonium fluoride (NH4F), and barium fluoride (BaF2) in rat pups. Two critical achievements made this comparative study possible: (a) the demonstration of significant increases in fluoride (F) uptake-deposition in the treatment group pups relative to control group rats as a result of stomach tube feeding; and (b) the demonstration of clear-cut differences in F concentration levels between the treatment groups as a result of this stomach tube-systemic uptake. Data were reliable and significant enough to suggest that, of the 3 compounds in question, NH4F is absorbed most successfully in a systemic fashion, whereas BaF2 is the least absorbed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02441172
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  • 5
    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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  • 6
    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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  • 7
    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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  • 8
    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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  • 9
    Electronic Resource
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    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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  • 10
    Electronic Resource
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    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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  • 11
    Electronic Resource
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    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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  • 12
    Electronic Resource
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    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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00381252
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  • 13
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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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00380114
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  • 14
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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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    URL: http://dx.doi.org/10.1007/BF00535771
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  • 15
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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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    URL: http://dx.doi.org/10.1007/BF00535450
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  • 16
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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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    URL: http://dx.doi.org/10.1007/BF00403506
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  • 17
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    Synaptology of the central nervous system of the freshwater snail Lymnaea stagnalis (L.), with particular reference to neurosecretion (1979)
    Springer
    Cell & tissue research 198 (1979), S. 217-235 
    Details
    ISSN: 1432-0878
    Keywords: Synaptic contacts ; Neurosecretion ; Lymnaea stagnalis ; Tilting stage electron microscopy ; Serial section reconstruction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In the central nervous system (CNS) of the freshwater snail Lymnaea stagnalis 3 types of interneuronal contacts can be distinguished electron-microscopically, viz. true synapses, “synapse-like structures” (SLS), and “spinules”. Use of the electron microscope specimen tilting stage reveals numerous true synapses. Both “terminal” and “en passant” contacts occur on neurones and on glial cells. Furthermore “bigeminal” synapses are present. Complex (combined) convergent and divergent synaptic arrangements are found. On the basis of the morphology of presynaptic vesicles 7 types of true synapses can be discerned. Histochemical data on the contents of the vesicles are lacking. However, vesicle morphology suggests that type IV is aminergic and type VII cholinergic. Terminal and en passant SLS may penetrate deeply into neuronal somata and large axons, and into glial cells. A cluster of synaptic vesicles is present in the presynapse-like element. Spinules (spine-coated “evagination-invagination” specializations of the plasma membranes of 2 adjacent neuronal elements) are observed between somata, between axons, and between soma and axon. The neurosecretory Light Green Cells (LGC) and Caudo-Dorsal Cells (CDC) receive complex synaptic input. Type V true synapses, 2 types of SLS, and spinules contact the LGC. The complex morphology of the relationship between type A SLS and LGC, studied in serial sections, reveals that adjacent glial cells are also contacted by type A SLS. Type II true synapses, 3 types of SLS, and spinules are identified on the CDC. The validity of the methods of identification and classification of interneuronal contacts in the CNS of L. stagnalis, as well as the role of these contacts in the regulation of the activity of “ordinary” neurones, neurosecretory cells, and glial cells is discussed.
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    URL: http://dx.doi.org/10.1007/BF00232006
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  • 18
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    The hypothalamo-hypophysial system in the ground squirrel, Citellus erythrogenys Brandt (1979)
    Springer
    Cell & tissue research 198 (1979), S. 539-556 
    Details
    ISSN: 1432-0878
    Keywords: Neurosecretion ; Ground squirrel (Citellus erythrogenys Brandt) ; Seasonal changes ; Hibernation ; Quantitative analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Monthly observations of the “Gomori-positive” hypothalamo-hypophysial neurosecretory system (HHNS) of the ground squirrel, Citellus erythrogenys Brandt, were carried out light microscopically using several quantitative methods. From the beginning of hibernation, formation of neurosecretory material (NSM) in the neurosecretory cells (NSC) progressively decreases and release of neurohormones from the HHNS is almost fully inhibited. A maximal accumulation of NSM in the perikarya of the NSC and in the posterior pituitary (PP) is found in December. By this time the volume of the cell nuclei and nucleoli is at a minimum. Signs of activation of the HHNS appear and become more conspicuous as the time of arousal from torpor approaches. The amount of NSM in the NSC and the PP decreases simultaneously with the increase in volume of the NSC. Hyperemia and activation of glial elements is visible throughout the HHNS. The morphological signs of activation reach their peak in March. After reproduction is completed (April to beginning of May), the NSC and the PP are almost devoid of NSM. Beginning with June and during the summer and autumn months a progressive accumulation of NSM in the NSC and the PP parallels gradual diminution in the volume of the NSC structures and the glial cells. Mechanisms and effector pathways by which the HHNS influences seasonal adaptation of the organism and reproduction are discussed.
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    URL: http://dx.doi.org/10.1007/BF00234197
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  • 19
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    Electron microscopic study of the giant cells in the olfactory bulb of labyrinth fish (Belontiidae, Perciformes) (1979)
    Springer
    Cell & tissue research 199 (1979), S. 509-517 
    Details
    ISSN: 1432-0878
    Keywords: Olfactory bulb ; Giant cells ; Neurosecretion ; Electron microscopy ; Labyrinth fish
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The giant cells in the olfactory bulb of labyrinth fish, most likely belonging to the nervus terminalis, show ultrastructural features of active synthesis of secretory material. Dense core vesicles (70–100 nm in diameter), found in the perikaryon as well as in the axon, are the possible storage sites of the secretory substance. Its chemical nature is unknown. In some of these vesicles acid phosphatase is demonstrable. Large membrane-bound bodies (up to 2000 nm in diameter), either containing an electron dense matrix or debris of cytoplasmic organelles, are also acid phosphatase-positive, suggesting their lysosomal nature. Some other ultrastructural characteristics of these cells are also described.
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    URL: http://dx.doi.org/10.1007/BF00236086
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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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    URL: http://dx.doi.org/10.1007/BF00237734
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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 
    Details
    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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    URL: http://dx.doi.org/10.1007/BF02185585
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    Ultrastructural development of the neurohemal organ joined to the ecdysial gland after imaginal moulting in the male isopod Sphaeroma serratum fab. (Crustacea Flabellifera) (1979)
    Springer
    Cell & tissue research 203 (1979), S. 403-414 
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    ISSN: 1432-0878
    Keywords: Neurohemal organ ; Neurosecretion ; Moulting gland ; Ultrastructure ; Crustaceans
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Résumé Chez Sphaeroma serratum, la mue de puberté est suivie d'une dégénérescence de l'organe Y (glands de mue). Le plexus nerveux céphalique latéral, organe neurohémal accolé à cette glande a été l'objet de la présente étude ultrastructurale. Cet organe représente un centre de stockage de neurosécrétions qui proviennent d'une part, de deux cellules autochtones (cellules plexales) situées au sein même de ce plexus, d'autre part, de cellules neurosécrétrices situées dans le “ganglion mandibulaire” (cellules de type A). Chez les individus pubères, les cellules plexales et les cellules A du ganglion sous-oesophagien synthétisent des granules de neurosécrétion dont la taille est respectivement 1550±50Å et 1570±40Å. Il a été reconnu au sein du plexus 5 catégories de terminaisons dont les granules proviendraient pour deux d'entre elles des cellules plexales et des cellules A du “ganglion mandibulaire”. Chez les animaux pubères on observe un arrêt de la synthèse des granules de neurosécrétion au sein des cellules plexales et des cellules A du “ganglion mandibulaire”. Simultanément on enregistre dans le plexus la raréfaction puis la disparition des divers types de granules. Ce processus atteint en premier les terminaisons correspondant aux cellules plexales et aux cellules A du “ganglion mandibulaire”. La dégénérescence de la glande de mue chez les mâles pourrait être en relation avec l'arrêt de synthèse de ces cellules.
    Notes: Summary The present ultrastructural study deals with the lateral cephalic nerve plexus of Sphaeroma serratum, a neurohemal organ joined to the Y organ (ecdysial gland). This plexus acts as a storage centre for neurosecretory products from two sources: the two autochtonous cells (plexus cells) within the plexus itself, and the neurosecretory cells in various parts of the central nervous system, particulary the “mandibular ganglion” (A-cells). In prepuberal animals, plexus cells and subesophageal A-cells produce neurosecretory granules of two types measuring 1550±50Å and 1570±40Å respectively. Five categories of axon terminals were distinguished in the plexus. The granules found in two of these terminal types are believed to come from the plexus cells and from the “mandibular ganglion” A-cells. Cessation of production of neurosecretory granules in these A cells and plexus cells was observed in puberal animals, in the plexus with concomitant depletion and disappearance of different granule categories. The first axon terminals affected by this process are the two categories containing granules originating in the plexus and “mandibular ganglion” A-cells. Degeneration of the ecdysial gland in male Sphaeroma serratum might be connected with the cessation of granule formation in these two types of cell.
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    Immunocytochemical identification of hyperglycemic hormone-producing cells in the eyestalk of Carcinus maenas (1979)
    Springer
    Cell & tissue research 204 (1979), S. 379-385 
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    ISSN: 1432-0878
    Keywords: Neurosecretion ; Immunofluorescence ; Crustacea ; X-organ ; Hyperglycemic Hormone
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Antiserum raised in rabbits against extracts of sinus glands from Carcinus and shown by several criteria to contain antibodies directed against the neurosecretory hyperglycemic hormone was used to locate the hormone-producing perikarya in the optic ganglia. By means of the double antibody fluorescence technique, selective staining of the large neurosecretory perikarya of the medulla terminalis ganglionic X-organ (MTGXO) and their axons is obtained. The axon endings of the sinus gland are also stained. None of the other groups of neurosecretory cells in the eyestalk shows fluorescence. Preabsorption of the antiserum with pure hyperglycemic hormone abolishes the fluorescence.
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    URL: http://dx.doi.org/10.1007/BF00233650
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    Ultrastructure of the corpus cardiacum and corpus allatum of the house cricket Acheta domesticus (1979)
    Springer
    Cell & tissue research 198 (1979), S. 201-208 
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    ISSN: 1432-0878
    Keywords: Neurosecretion ; Corpus cardiacum ; Corpus allatum ; Acheta domesticus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The ultrastructure of the corpus cardiacum (CC) and corpus allatum (CA) of the house cricket, Acheta domesticus, is described. Axon profiles within the CC contain neurosecretory granules 160–350 nm in diameter which are indistinguishable from those found in type I neurosecretory cells of the pars intercerebralis and in the nervus corporis cardiaci I. The CC itself contains two cell types: intrinsic neurosecretory cells and glial cells. Intrinsic NSC cytoplasm contains Golgi bodies and electron dense neurosecretory granules 160–350 nm in diameter. Synaptoid configurations with 20–50 nm diameter electron lucent vesicles were observed within axon profiles of the CC. The structure of the CA is relatively uniform with one cell type predominating. Typical CA cells possess large nucleoli, active Golgi complexes, numerous mitochondria, and occassional microtubules. Groups of dark staining cells scattered throughout the CA of some animals were interpreted as evidence of cellular death.
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    URL: http://dx.doi.org/10.1007/BF00232004
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    The neurosecretory hypothalamo-hindbrain pathway and its possible significance for the regulation of blood pressure and the milk-ejection reflex (1979)
    Springer
    Cell & tissue research 196 (1979), S. 321-336 
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    ISSN: 1432-0878
    Keywords: Neurosecretion ; Hypothalamo-hindbrain pathway ; Rat ; Blood pressure ; Milk ejection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary 1. In lactating rats and in rats deprived of water, the amount of neurosecretory material in the fibres of the neurosecretory hypothalamohindbrain pathway exceeds that in untreated control animals. Under these experimental conditions the pathway and its target regions can be well analysed by means of fluorescence and electron microscopic methods. 2. The axons belonging to the hypothalamo-hindbrain pathway originate from perikarya located in the caudal portion of the nucleus paraventricularis and also from a small group of perikarya in the caudo-lateral hypothalamus. On the way to the hindbrain the neurosecretory fibres join other fibre bundles of the mid- and hindbrain. 3. In the hindbrain most of the neurosecretory fibres terminate in the area of the nucleus tractus solitarii and in the area of the dorsal column nuclei. The axon terminals form synapses with other neurones. 4. Using cytochemical methods at the ultrastructural level (Naumann and Sterba, 1976), the authors were able to prove that the vesicles in the exohypothalamic fibres and in their synaptic terminals contain the same sort of material as the neurophysin vesicles in the posterior lobe of the hypophysis. 5. The most distinct increase in neurophysin was observed in lactating females which were separated from their sucklings after a normal lactation period of 15 days and killed four days thereafter, and in rats deprived of water for different time periods. 6. The relationship of the neurosecretory hypothalamo-hindbrain pathway to the nucleus tractus solitarii and to the dorsal column nuclei suggests that, functionally, there may be a correlation between the system of blood-pressure control and the milk ejection reflex.
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    URL: http://dx.doi.org/10.1007/BF00240105
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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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    Bone mineral turnover in a patient with osteogenesis imperfecta estimated by fluoride excretion (1978)
    Springer
    Calcified tissue international 25 (1978), S. 283-287 
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    ISSN: 1432-0827
    Keywords: Fluoride ; Osteogenesis imperfecta ; Bone turnover
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary A child with severe osteogenesis imperfecta was treated with NaF for 8 years, at the end of which time his iliac bone contained 29 mg F/g Ca. Urine F was assayed at intervals for 4.5 years after discontinuing treatment. After the first few days the decline in urinary F excretion can be described by a twocomponent exponential function, with half-times of 5.4 months (10%) and 8.9 years (90%). The latter half-time value is of the same order of magnitude as those observed for F and other “bone-seeking” elements in normal subjects, which suggests that the turnover rate of bone mineral is normal in this disease. Three methods for estimating the attained body F burden at the end of NaF treatment — namely, metabolic balance, bone biopsy, and integration of the exponential function — yielded comparable values.
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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)
    Springer
    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)
    Springer
    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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    Scanning and transmission electron microscopy of the subfornical organ of the grass frog (Rana pipiens) (1978)
    Springer
    Cell & tissue research 186 (1978), S. 361-374 
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    ISSN: 1432-0878
    Keywords: Subfornical organ ; Circumventricular organs ; CSF-contacting neurons ; Encephalo-chromaffin cells ; Neurosecretion ; Rana pipiens
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The ventricular surface of the subfornical organ of the frog is made up of ependymal cells with numerous apical microvilli, occasional cytoplasmic protrusions and many vacuoles projecting into the lumen of the third ventricle. Between these cells dendrites of cerebrospinal fluid-contacting neurons reach the ventricle to terminate in bulbous enlargements. In addition, flask-shaped encephalo-chromaffin cells, containing granulated vesicles and aggregates of filaments in their cytoplasm, project into the cerebrospinal fluid. Surrounding the centrally located capillaries are enlarged dendrites and axons of heterogeneous morphology, some of which appear to originate within the subfornical organ, intermingled with dendrites and axons of normal structure. The glial cells in this region, especially the microglial cells, often contain large lipofuscin inclusions, suggestive of degeneration and subsequent phagocytosis of some of the enlarged dendrites and axons. The normally scarce neurosecretory peptidergic axons become more evident and form typical Herring bodies in stalk-transected animals. Neuronal perikarya of varying morphology are predominantly located peripheral to the region of enlarged dendrites and axons. Supraependymal macrophages are particularly numerous on the subfornical organ.
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    Distribution of fibres reacting with an α-endorphin antiserum in the neurohypophysis of Carassius auratus and Cyprinus carpio (1978)
    Springer
    Cell & tissue research 189 (1978), S. 251-256 
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    ISSN: 1432-0878
    Keywords: α-Endorphin ; Neurosecretion ; Fish pituitary ; Hypothalamohypophyseal relationships ; Immunocytology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary A strong positive immunoreaction with an α-endorphin antiserum occurs in two distinct sites of the goldfish and carp neurohypophysis. Fluorescent nerve terminals are found in the laminar nerve processes located in the rostral pars distalis, but the immunocytological reaction is mainly localised on the nerve processes of the posterior neurohypophysis lying between the intermediate lobe cells. Almost all the digitations of the neurohypophysis are strongly fluorescent. The immunoreactive fibres probably originate from the hypothalamus, where perikarya displaying the same immunoreaction have been found in the pars lateralis of the nucleus lateralis tuberis and in some minor centres. The possibility that the immunoreactive substances revealed on the neurohypophyseal processes may originate in the intermediate lobe cells is also discussed. It has now to be established if this hypothalamo-hypophyseal system contains a substance with endorphic properties or only some immunologically related substance devoid of the corresponding physiological activities.
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    URL: http://dx.doi.org/10.1007/BF00209274
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    Synaptic junctions in the sinus gland of the freshwater prawn Palaemon paucidens (1978)
    Springer
    Cell & tissue research 189 (1978), S. 435-440 
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    ISSN: 1432-0878
    Keywords: Neurosecretion ; Sinus gland ; Synapses ; Palaemon ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Two types of neurosecretory fibers, designated as Type 5 and Type 6 axons, in the sinus gland of the freshwater prawn, Palaemon, establish contact with other neurosecretory axons by means of synaptic junctions. This finding strongly supports the view that release of some neurohormones from the eyestalk may be regulated by neurosecretory neurons through synaptic transmission.
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    The hypothalamo-hypophysial system in acipenseridae (1978)
    Springer
    Cell & tissue research 186 (1978), S. 559-570 
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    ISSN: 1432-0878
    Keywords: Nucleus praeopticus ; Neurosecretion ; Acipenseridae ; Quantitative study
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The peptidergic neurosecretory cells (NSC) of the nucleus praeopticus (NP) of male and female sturgeons, A. güldenstädti Brandt, were studied light microscopically at different stages of their life cycle and under experimental conditions. Four main NSC types reflecting different phases of secretory cycle and life course of the cell have been tentatively distinguished. The maximum percentage of the high and moderate active NSC are found in juvenile animals in the sea (stages I and I–II of gonadal maturity, sgm), in upstream migrating fish in spring before spawning, in down-stream migrating fish 1–1.5 months after spawning, and in experimental fish kept for 8.5 hours in a 32‰ sodium chloride solution. The least active NSC accumulating neurosecretory material (NSM) are characteristic of juvenile fish (sgm II) in the sea, sturgeons maintained in a sodium chloride solution for 3.5 or 6 hours and fish which remained in a net, thrown to the sea, for some hours before fixation. The lowest percentage of these cells is observed in autumn migrants, in females soon after spawning (sgm VI) and in fish kept for 8.5 hours in a sodium chloride solution. Cells rich in basophilic substance and poor in NSM occur in juvenile and in down-stream migrating fish. Cells reflecting the state of exhaustion after hyperactivity and “ageing” cells are seen in adults, especially in sgm VI fish, and in autumn migrants. Pyknomorphous NSC are constantly present in all fish; they are most numerous in sturgeons found in a net. A diagram demonstrating the life course and the secretory cycle of the NSC is presented and the role of the hypothalamo-hypophysial neurosecretory system (HHNS) under stress conditions is discussed.
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    Immunofluorescence of somatostatin-producing sites in the hypothalamus of the tadpole, Alytes obstetricans Laur. (1978)
    Springer
    Cell & tissue research 187 (1978), S. 315-321 
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    ISSN: 1432-0878
    Keywords: Hypothalamus ; Tadpole, Alytes obstetricans ; Neurosecretion ; Somatostatin ; Immunofluorescence
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Three sites of somatostatin-synthesizing perikarya, or a related antigen, were determined by immunofluorescence in the hypothalamus of the tadpole, Alytes obstetricans (Amphibia, Anura). Two sites of neurosecretory perikarya were localized in the preoptic nuclei of the anterior hypothalamus; the axons extended either to the anterior diencephalon or to the median eminence and the pituitary. The third site was found in the posterior hypothalamus. These neurosecretory cells showed a strong immunofluorescent reaction; their axons all terminated at the level of the median eminence. Somatostatin cells were only found in intact or hypophysectomized tadpoles given somatotropin (STH). The strong reaction observed in hypophysectomized tadpoles was possibly due to the loss of the terminal portion of the neurosecretory pathway (median eminence and pituitary) by which the agent is transported to the site of discharge.
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    The ultrastructure of the herring bodies in rats subjected to different experimental conditions (1978)
    Springer
    Cell & tissue research 189 (1978), S. 41-51 
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    ISSN: 1432-0878
    Keywords: Herring bodies (rat) ; Colchicine ; Cold ; Neurosecretion ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary A study of the morphology of Herring bodies of the posterior pituitary lobe of rats treated with colchicine and/or exposed to low temperatures has been performed. After treatment with colchicine (20 μg in distilled water injected intracisternally) a predominance of Herring bodies with a large number of small “synaptic-like” vesicles surrounded by neurosecretory granules is found. Exposures to low temperature (4–6° C) result in an increase in the neurosecretory material and the Herring bodies show many neurosecretory granules of different densities. After treatment with colchicine and subsequent exposure to low temperatures, the Herring bodies are characterized by having a great number of autophagic bodies which become more numerous as the length of the exposure is increased; later autophagic vacuoles and lamellar bodies become evident.
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    URL: http://dx.doi.org/10.1007/BF00223120
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    Catharanthine: A novel stimulator of pancreatic enzyme release (1978)
    Springer
    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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    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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    Structural re-evaluation of the neurosecretory system in the crayfish eyestalk (1978)
    Springer
    Cell & tissue research 190 (1978), S. 235-246 
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    ISSN: 1432-0878
    Keywords: Neurosecretion ; Cobalt backfilling ; Crustacea ; Sinus gland ; X organ
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The topography of the neurosecretory system in the decapod eyestalk has not been precisely delineated with light microscopy. Cobalt iontophoresis and electron microscopy have proved useful in clarifying the microstructure of this system. The sinus gland (sg) of the crayfish eyestalk consists of aggregated axon terminals which end at or near the blood space, lontophoresing cobalt back through the cut base of the sinus glands reveals proximal cell bodies in the eyestalk only in the X organ (Xo) region. Electron microscopy demonstrates that axons from about 115 neurosecretory cell bodies in the Xo form the Xo-sg tract. Intermingled with these Xo somata are smaller non-neurosecretory cell bodies which do not send axons into the sinus gland. One of these exhibits catecholamine fluorescence. Backfilling also reveals a second group of fibres which run from the brain along the optic tract and into the sinus gland. These brain-sg fibres are smaller in diameter than Xo-sg axons and lack neurosecretory vesicles. From these fibres collaterals extend into the eyestalk neuropil, especially in the proximity of the visual elements. The possible function of these non-neurosecretory processes within the sinus gland is discussed.
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    Fine structural and cytochemical study of the innervation of smooth muscle in an amphibian (Bufo marinus) lung before and after denervation (1978)
    Springer
    Cell & tissue research 194 (1978), S. 419-432 
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    ISSN: 1432-0878
    Keywords: Lung ; Bufo marinus ; Innervation ; Adrenergic nerves ; Neurosecretion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The innervation of the toad (Bufo marinus) lung was studied with transmission electron microscopy and fluorescence techniques, both before and after 12 or 20 days close vagosympathetic denervation. Four cytologically distinct types of neuronal processes were recognised, in relation to the visceral muscles of the lung. These were described as cholinergic, adrenergic, nonadrenergic/non-cholinergic (NANC) and sensory on the basis of the characteristics of their vesicular content and cytochemical reactions. An apparent efferent innervation of visceral smooth muscle was achieved by NANC (50%), cholinergic (25%) and adrenergic (25%) fibres. A few sensory fibres were also present. After denervation only NANC fibres persisted, showing that the cell bodies of these fibres were intrapulmonary. The vascular smooth muscle was supplied by cholinergic, adrenergic and sensory fibres. In the walls of the proximal branches of the pulmonary artery were fibres containing large dense-cored vesicles. These profiles, which were associated with the vasa vasorum, were similar to neurosecretory fibres. After denervation all neural profiles associated with the vasculature had degenerated. The observations suggest that vagal vasodepressor effects in the toad lung are mediated indirectly through relaxation of visceral muscle strands which in their contracted state compress vascular channels.
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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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    Effect of local application of fluoride on healing of experimental bone fractures in rabbits (1977)
    Springer
    Calcified tissue international 22 (1977), S. 297-302 
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    ISSN: 1432-0827
    Keywords: Fluoride ; Gelfoam ; Fracture ; Ossification ; Breaking force
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract The effect of local application of low fluoride concentrations on the healing of experimental bone-radii fractures in 20 rabbits was examined. No external fixation was required after the osteotomy and gelfoamℜ being used as a medium for fluoride application. Histologic mineral and mechanical strength measurements were carried out on the healing callus. There were no significant changes in the ashpercentage and the fluoride concentration of the ash between the experimental and control callus. A significantly higher percentage of ossified tissue was found in the fluoride treated callus. The breaking strength was found to be significantly higher in the bone fractures treated with fluoride, whereas there was no notable difference between the surface areas. It is postulated that the greater amount of ossified tissues, the differences in organization of the bone trabecules, and/or an improved mineral crystallinity may be responsible for this result.
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    The temperature dependency of45Ca diffusion in bovine enamel (1977)
    Springer
    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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    A micromethod for the determination of fluoride in blood plasma and saliva (1977)
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    Calcified tissue international 23 (1977), S. 225-228 
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    ISSN: 1432-0827
    Keywords: Fluoride ; Analysis ; Blood ; Saliva
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary A simple and accurate technique for the determination of fluoride (F−) in capillary-sampled blood is presented. The method is based on the known addition-slope determination technique using the fluoride electrode is required. A standard deviation of 1.3–5.6% in the range 300–10 ng F/ml was given by 259 duplicate determinations on human plasma. Measurements of parotid saliva showed that it was possible to analyze fluoride concentrations as low as 4 ng F/ml with good reproducibility. The results also show that a 150 μl sample is sufficient for fluoride determination with high accuracy. This method can easily be used in a clinical laboratory.
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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)
    Springer
    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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    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)
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    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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    Plasma fluoride and enamel fluorosis (1977)
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    Calcified tissue international 22 (1977), S. 77-84 
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    ISSN: 1432-0827
    Keywords: Fluoride ; Blood plasma ; Enamel mineralization ; Rat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract It is postulated that tissue fluid F concentrations are the primary determinants of fluoride effects on bones and developing teeth and that these concentrations are dependent on, or mirrored by, blood plasma F. It has earlier been shown that the plasma F levels are dependent on the dietary F supply as well as on skeletal F concentration. Fasting and post-ingestion or postinjection plasma F levels have been determined in rats on F doses that cause different degrees of enamel fluorosis. The results indicate that temporary peak values rather than elevated fasting values are responsible for the occurrence of enamel fluorosis and that the peak values must approach about 10 μM in order to block enamel formation by the ameloblasts. The diagnostic and prognostic importance of plasma F determinations is discussed.
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    A model-independent comparison of the rates of uptake and short term retention of47Ca and85Sr by the skeleton (1977)
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    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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    Pharmacokinetics of fluoride in man after single and multiple oral doses (1977)
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    European journal of clinical pharmacology 12 (1977), S. 311-317 
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    ISSN: 1432-1041
    Keywords: Fluoride ; single- and multiple dose kinetics ; plasma concentration ; urinary excretion ; saliva/plasma concentration ratio
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The doses of fluoride (F) recommended in the literature for caries prevention and for the treatment of osteoporosis vary. This partly reflects inadequate knowledge of F pharmacokinetics. In the present study various single and multiple oral doses of F were given to eight volunteers, who had a strictly controlled F intake in the diet. The resulting plasma and parotid saliva concentrations as well as urinary output of F were measured. The plasma data fitted a two-compartment open model with a β-slope half-life ranging between 2 and 9 h. Plasma clearance was 0.15±0.02 (SD) liter/kg/h. Data from the highest dose (10 mg) were fitted to both two- and three-compartment models, and there was no significant difference between them. Multiple doses of F 3.0 or 4.5 mg yielded steady state concentrations ranging from 54 to 145 ng/ml. About 50 per cent of the given dose was recovered in the urine, which is indicative of considerable accumulation in the body. The saliva F/plasma F concentration ratio was 0.64 with a coefficient of variation of 5%.
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    The ultrastructure of the sinus gland of Gammarus oceanicus (Crustacea: Amphipoda) (1977)
    Springer
    Cell & tissue research 182 (1977), S. 557-564 
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    ISSN: 1432-0878
    Keywords: Sinus gland ; Gammarus ; Neurosecretion ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The sinus gland of Gammarus oceanicus, like that of other crustaceans, is composed of three elements: neurosecretory axons, glial cells and stromal sheath. Five neurosecretory axon types are identified on the basis of granule diameter, shape, and electron density, and axon matrix density. Exocytosis appears to be the major release mechanism of neurosecretory material. The preterminal regions of neurosecretory axons contain axoplasmic reticulum and neurotubules. Their arrangement in the axon and relationship with one another suggest a transport function. Multilamellar bodies are found in the terminal regions of neurosecretory axons. They arise from mitochondria and may be involved in granulolysis.
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    Neurosecretion in the basommatophoran snail Bulinus truncatus (Gastropoda, Pulmonata) (1977)
    Springer
    Cell & tissue research 176 (1977), S. 57-67 
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    ISSN: 1432-0878
    Keywords: Neurosecretion ; Alcian blue ; Alcian yellow staining ; Ultrastructure ; Bulinus truncatus
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The neurosecretory system of the freshwater snail Bulinus truncatus was investigated. With the Alcian blue-Alcian yellow (AB/AY) staining method at least 10 different types of neurosecretory cells (NSC) were distinguished in the ganglia of the central nervous system. The differences in staining properties of the NSC — with AB/AY the cells take on different shades of green and yellow — are borne out at the ultrastructural level: the NSC types contain different types of neurosecretory elementary granules. The neurosecretory system of B. truncatus is compared to that of Lymnaea stagnalis, the species which has received the most attention among the pulmonates. It appears from the comparison that the systems of both species show many similarities, although some differences are also apparent.
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    Homologous neurosecretory cell groups in the land snail Achatina fulica and the sea slug Aplysia californica (1977)
    Springer
    Cell & tissue research 176 (1977), S. 109-120 
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    ISSN: 1432-0878
    Keywords: Achatina fulica ; Aplysia californica ; Neurosecretion ; Homology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The right parietal ganglion of the African snail Achatina fulica contains an identifiable cluster of 20–40 white cells with somatic diameters of 80–110 μ. Cobalt chloride injection into these cells revealed an axon projection in the right parietal nerve as well as apparent terminations in the capsule. The cells contain an abundance of electron dense granules 1000–2000 Å in diameter which are formed in the Golgi apparatus. The granules stain with Gomori's chrome hematoxylin and paraldehyde fuchsin methods. While most cluster cells showed no “spontaneous” electrical activity, there was a correlation for the active cells between rate of activity and intensity of cell whiteness. These and other data suggest that the cluster cells are neurosecretory. A claim of homology with the “rostral white cells”, R3–R13, in the parieto-visceral ganglion of Aplysia is based on a similarity of morphological and electrophysiological features, together with analogous locations in the respective ganglia. It is concluded that the right parietal ganglion of Achatina is homologous with the right half of the parieto-visceral ganglion of Aplysia.
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    Microtubules in the neurosecretory neurones of the posterior pituitary of the rat (1977)
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    Cell & tissue research 180 (1977), S. 253-261 
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    ISSN: 1432-0878
    Keywords: Microtubules ; Neurohypophysis ; Neurosecretion ; Axoplasmic transport
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The microtubules in the neurosecretory neurones of the posterior pituitary were studied using different electron microscopical techniques. Tannic acid staining indicated that the microtubules had a 13 protofilament substructure similar to that described for microtubules from other tissues and organisms; the dimensions of the microtubules were also similar to that previously reported. Albumen pretreatment clearly showed the microtubules running across axonal swellings, but not continuing across the nerve endings. The only organelles showing possible association with the microtubules were small vesicles and smooth endoplasmic reticulum, no association between hormone granules and microtubules could be seen.
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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 hypothalamo-choroidal tract (1977)
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    Cell & tissue research 178 (1977), S. 129-141 
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    ISSN: 1432-0878
    Keywords: Choroid plexus ; Vasopressin ; Neurosecretion ; Rat ; Electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Light and electron microscopic examination of choroid plexuses from lateral ventricles of water-deprived and subcutaneously or intravenously vasopressin administered rats reveal morphologic changes typical for vasopressin responsive fluid transporting epithelia during hormonal stimulation. Ultrastructural changes noted in both dehydrated and vasopressin treated animals included: the frequent occurrence of choroidal “dark” cells, dilatation of the lateral and basal intercellular spaces, increased vacuolization of the apical cytoplasm, and a change in microvillar conformation from the normal clavate type to those with a filiform shape. On the basis of the ultrastructural changes observed it is proposed that the choroid plexus be regarded as a target tissue for vasopressin. These findings indicated that a vasopressinmediated transchoroidal cerebrospinal fluid absorption capability exists.
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    The hypothalamo-hypophysial system in acipenseridae (1976)
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    Cell & tissue research 170 (1976), S. 113-128 
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    ISSN: 1432-0878
    Keywords: Neurohypophysis ; Neurosecretion ; Acipenseridae ; Spawning ; Stress
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Neurohypophyses from sexually mature female sturgeons, Acipenser güldenstädti Brandt, killed before, soon after spawning, and during down-stream migration were studied light and electron microscopically. Ovaries were examined only under a light microscope. A large amount of neurosecretory material (3.5–4.5 arbitrary units) is found in the neurohypophysial “roots” during up-stream migration to spawning grounds. Neurosecretory fibres and their terminals are replete with elementary neurosecretory granules. Side by side with the latter some terminals contain single residual granules and few “synaptic” vesicles. Soon after spawning the amount of neurosecretory material decreases markedly in most individuals (content up to 1–3 units), and elementary granules are few in the fibres and their terminals. The number of residual granules increases, and “synaptic” vesicles are especially numerous. Granulated, disintegrating neurosecretory granules and granule-shadows occur in the preterminal parts of the fibres. The number of pituicytes increases because some “light” tanycytes seem to migrate from the ependymal into the subependymal layer. The restoration of neurosecretory material (reaching again up to 3.5–4.5 units) occurs within a month after spawning. The number of elementary granules increases in fibres and terminals while that of residual granules and “synaptic” vesicles decreases. These changes in the neurohypophysis of females after spawning are due to discharge of great amounts of peptide neurohormones into the general circulation after spawning. Spawning is regarded as a “physiological” stress for these females.
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    An ultrastructural in vitro study on the regulation of neurosecretory activity in the freshwater snail Lymnaea stagnalis (L.) with particular reference to Caudo-dorsal cells (1976)
    Springer
    Cell & tissue research 174 (1976), S. 201-219 
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    ISSN: 1432-0878
    Keywords: Neurosecretion ; Lymnaea stagnalis ; Neuron isolation ; Culture ; Quantitative electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The neurosecretory Caudo-Dorsal Cells (CDC) in the cerebral ganglia of the freshwater pulmonate snail Lymnaea stagnalis produce an ovulation stimulating hormone. Previously it has been shown that neuronal and non-neuronal inputs are involved in the regulation of their activity. The degree of autonomy of these cells has been investigated by studying with morphometric methods the ultrastructure of CDC maintained in vitro. CDC of isolated cerebral ganglia which were cultured for 7 days show a considerable rate of synthesis, transport and release of neurohormone. Apparently these processes can proceed in the absence of neuronal and hormonal inputs from outside the cerebral ganglia. Completely isolated CDC, however, do not show neurosecretory activity in vitro; active Golgi zones, indicating the formation of neurosecretory elementary granules, are absent from such cells. Isolation does not seem to affect general cell functions such as protein synthesis and respiration. It is suggested that a neuronal input, originating within the cerebral ganglia, is necessary for the stimulation of CDC neurosecretory activity. Techniques are described for the isolation and culture of neurosecretory cells of L. stagnalis.
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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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    Effect of calcium depletion and subsequent repletion on parathyroids, parafollicular (C) cells and bone in the growing pig (1976)
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    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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    Direct innervation of the mantle edge gland by neurosecretory axons in Helisoma duryi (Mollusca: Pulmonata) (1976)
    Springer
    Cell & tissue research 171 (1976), S. 397-401 
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    ISSN: 1432-0878
    Keywords: Mantle edge ; Neurosecretion ; Gastropoda ; Innervation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The mantle edge gland of Helisoma duryi is innervated by neurosecretory axons from the pallial nerves. Synaptoid contacts occur between axons and gland cells, and there is ultrastructural evidence for the release of neurosecretory material. The mantle edge gland contributes to the deposition of periostracum during shell formation, and direct neurosecretory innervation may control shell growth and regeneration.
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    Granulolysis in neurosecretory neurons of the rat supraoptico-posthypophyseal system (1976)
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    Cell & tissue research 172 (1976), S. 39-58 
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    ISSN: 1432-0878
    Keywords: Neurosecretion ; Posterior lobe of hypophysis ; Supraoptic nucleus ; Granulolysis ; Lysosomes ; Acid phosphatase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Résumé Les images ultrastructurales et cytochimiques de l'activité sécrétrice et lysosomiale des neurones neurosécréteurs supraoptico-posthypophysaires du rat ont été observées dans des circonstances où le nombre des grains de neurosécrétat et des lysosomes varient fortement. Au début de la réhydratation, après privation d'eau de 4 J, se développe dans les axones du lobe postérieur de l'hypophyse, plus ou moins vides de leurs grains, une autophagie intense. Elle intéresse surtout le réticulum lisse, abondant à ce stade, des microvésicules et des grains, bien que ces derniers soient encore peu nombreux. Si, à la reprise de la boisson, le transport axonal est inhibé par la colchicine, les grains s'accumulent dans les périkaryons, et le lobe postérieur ne se recharge pas. Toutefois l'autophagie, toujours intense dans les axones, reste très faible dans les périkaryons où la crinophagie n'est pas évidente. L'hypophysectomie induit également une charge granulaire des périkaryons, sans granulolyse importante; la mise en évidence des phosphatases acides fournit quelques images de crinophagie possible. Ce mécanisme est localisé exclusivement dans les périkaryons et l'autophagie essentiellement dans les axones. L'autophagie paraît constituer le mode de granulolyse prédominant et doit être considérée ici comme un des aspects du turnover des constituants cellulaires, signifiant un arrêt brusque d'une hypertrophie par hyperfonctionnement, plutôt que comme la régulation spécifique d'un excès de sécrétion.
    Notes: Summary Ultrastructural and cytochemical observations on neurosecretory neurons of the rat supraoptico-posthypophyseal systems were made under experimental conditions which resulted in striking changes in the amount of neurosecretory granules and lysosomes. Attention was focused on granulolysis. At the onset of rehydration following a 4 days water deprivation, very active autophagy took place in neurosecretory axons of the neural lobe involving the marked increase in smooth endoplasmic reticulum, microvesicles and neurosecretory granules, although the latter were still very few due to previous depletion. When axonal transport was inhibited by colchicine at the onset of rehydration, granules accumulated in the perikarya while granule reloading of the neural lobe was delayed. However autophagy, although always active in axons, remained scarce in perikarya. Moreover, in the latter there was only slight evidence of crinophagy. Hypophysectomy also induced granule accumulation in the perikarya, although accompanied by little granulolysis. Images indicative of crinophagy as shown by acid phosphatase localization were few and exclusively restricted to perikarya, while autophagy occurred essentially in axons. Autophagy appeared to be the predominant process for granulolysis and might be considered here as an aspect of the general turnover of cell constituents, related to the sudden regression of hyperactivity-induced hyperthrophy, rather than as an expression of a specific regulation of an excess of secretory material.
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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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    URL: http://dx.doi.org/10.1007/BF00221375
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    The primate median eminence II (1976)
    Springer
    Cell & tissue research 175 (1976), S. 265-277 
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    ISSN: 1432-0878
    Keywords: Median eminence ; Macaca mulatto ; High-voltage electron microscopy ; Neurosecretion ; Ependymal cells
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The ultrastructure of the normal median eminence of the male rhesus monkey (Macaca mulatta) is described using high-voltage electron microscopy. Surface specializations of ependymal cells lining the infundibular recess included cilia, apical extrusions, and microvilli. Supraependymal cells were predominantly macrophage-like, but examples of lymphocytic types were also seen. Tanycytes had long, branching, basal processes filled with numerous microtubules, some lipid droplets, and granules. The zona interna was composed of large unmyelinated neurosecretory fibers. A few myelinated fibers were also seen, but their character as neurosecretory fibers could not be established. The zona externa was composed of densely-packed profiles of neurosecretory fibers of small diameter, was well-vascularized and contained the terminations of tanycytes. Perivascular glial cells, vesiculated elements, pituicytes, and cellular elements common to connective tissue were observed. The intricate relationships between both the cellular and fibrous elements of the median eminence can be appreciated with the capability of high-voltage electron microscopy to discern ultrastructure in sections 10 times thicker than those used for low-voltage electron microscopy. The median eminence of this primate species has an ultrastructural organization similar to that described for most other species.
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    URL: http://dx.doi.org/10.1007/BF00232082
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    Morphometric in vitro analysis of the control of the activity of the neurosecretory dark green cells in the freshwater snail Lymnaea stagnalis (L.) (1976)
    Springer
    Cell & tissue research 174 (1976), S. 221-231 
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    ISSN: 1432-0878
    Keywords: Neurosecretion ; Lymnaea stagnalis ; Osmoregulation ; In vitro ; Quantitative electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The neurosecretory Dark Green Cells (DGC) in the pleural and parietal ganglia of the freshwater snail Lymnaea stagnalis seem to be involved in osmoregulation. Previous experiments have indicated that changes of the osmolality of the environment induce activity changes of the DGC. Furthermore, it was shown that information on environmental osmolality reaches the DGC via the blood. In the present study right pleural and parietal ganglion complexes were cultured for 3 days in vitro under different osmotic conditions. Quantitative electron microscopy revealed that, compared with the control osmolality (130 mOsm/kg H2O), osmolalities of 160 and 190 mOsm/kg H2O caused a reduced synthesis and an increased storage of neurohormone in the DGC. Apparently, the activity of the DGC depended on the osmotic pressure of the medium. It is proposed that in vivo the osmotic pressure of the blood (which is related to the osmolality of the environment) regulates DGC activity.
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    URL: http://dx.doi.org/10.1007/BF00222160
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    Neuronal and non-neuronal control of the neurosecretory Caudo-Dorsal cells of the freshwater snail Lymnaea stagnalis (L.) (1976)
    Springer
    Cell & tissue research 168 (1976), S. 11-31 
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    ISSN: 1432-0878
    Keywords: Neurosecretion ; Regulatory input ; Lymnaea stagnalis ; Synapse degeneration ; Quantitative electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The cerebral ganglia of the freshwater snail Lymnaea stagnalis contain two clusters of neurosecretory Caudo-Dorsal Cells (CDC). These cells produce a neurohormone which stimulates ovulation. Ganglion transplantation and quantitative electron microscopy show that neuronal isolation of the cerebral ganglia complex (CCC) results in an activation of the CDC. It was, therefore, concluded that the CDC are controlled by an inhibitory neuronal input originating outside the cerebral ganglia. Ultrastructural studies on synaptic degeneration in the CCC suggest that this input reaches the CDC via a special type of synapse-like structure, the type C-SLS. Furthermore, transplantation of CCC into acceptor snails leads to a reduced release and an increased intracellular breakdown of neurohormone in the CDC of the nervous system of the acceptors. It is supposed that these phenomena are caused by the release of an (unknown) factor from the transplanted CCC. Special attention was given to the formation and degradation of a peculiar type of neurohormone granule, the large electron dense granule. The physiological significance of the neuronal and non-neuronal control mechanisms which regulate CDC activity is discussed.
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    URL: http://dx.doi.org/10.1007/BF00219720
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    Histological and histochemical observations on the neurosecretory cells in the diencephalon of Chthonerpeton indistinctum and Ichthyophis paucisulcus (Gymnophiona, Amphibia) (1976)
    Springer
    Cell & tissue research 175 (1976), S. 137-145 
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    ISSN: 1432-0878
    Keywords: Diencephalon ; Gymnophiona ; Nucleus praeopticus ; Neurosecretion ; Acetylcholinesterase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary In the diencephalon of two species of Gymnophiona (Amphibia) two neurosecretory nuclei were examined with histological (Alcian Blue, Aldehyde Fuchsin, Brookes Trichrome stain) and enzyme histochemical techniques (acid phosphatase, α-naphthyl acetate esterase, acetylcholinesterase (AChE)). In the preoptic nucleus two categories of secretory neurons were distinguished: large and medium sized neurons. The perikarya of both cell types contain very little neurosecretory material. The Alcian Blue method stained the medium sized neurons faintly but selectively. The tractus praeopticohypophyseus is marked by the presence of Herring bodies, which, however, are relatively scarce. The neurohypophysis, in contrast, contains large amounts of neurosecretory material. Both cell types of the preoptic nucleus are characterized by their very strong AChE and α-naphthylacetate esterase activity. The AChE also marks the tractus praeoptico-hypophyseus. In the large neurons acid phosphatase is present around the nucleus; in the medium sized neurons this enzyme is concentrated close to the origin of the axon. In the dorso-caudal hypothalamus a small group of neurons is stained with Alcian-Blue. These neurons, which also contain AChE, are located immediately under the ependyma which seems to be specialized in this region.
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    A comparison of aldehyde fuchsin and alcian blue staining of neurosecretory material in Oncopeltus fasciatus (1975)
    Springer
    Cell & tissue research 161 (1975), S. 477-484 
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    ISSN: 1432-0878
    Keywords: Neurosecretory cells ; Oncopeltus fasciatus ; Neurosecretion ; Neurophysin ; Aldehyde fuchsin ; Alcian blue
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The dynamics of the “A” cells of the parsintercerebralis of Oncopeltus fasciatus over the first eight days of adult life was studied by microspectrophotometry of sections stained either with aldehyde fuchsin or alcian blue 8 GX. The data show that the two stains differ in their selectivity as they record different events in the history of the cells. A hypothesis is proposed that the aldehyde fuchsin is more sensitive to the presence of a “carrier” protein in the cell, whereas alcian blue 8 GX is more sensitive to the presence of the “active principle” in the cell.
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    URL: http://dx.doi.org/10.1007/BF00224138
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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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    URL: http://dx.doi.org/10.1007/BF00219469
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    Movement of neurosecretory product through the anatomical compartments of the neural lobe of the pituitary gland (1975)
    Springer
    Cell & tissue research 156 (1975), S. 483-497 
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    ISSN: 1432-0878
    Keywords: Neurohypophysis ; Neurosecretion ; Neurophysin ; Neurohypophysia hormones ; Electron microscopy ; Autoradiography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Electron-microscope autoradiographs have been prepared from the neural lobes of the pituitary glands of rats which had received intracisternal injections of [35S] cysteine at various times before gland removal. The rate of appearance and disappearance of autoradiographically demonstrable radioactivity in the neural lobe closely paralleled that previously determined, biochemically, for radioactive hormones and neurophysins. Radioactivity was appreciably associated with the undilated parts of neurosecretory axons only during the first few hours after injection of the label. The axonal dilations were subdivided into those in which small vesicles could be seen (“endings”) and those in which no small vesicles could be seen (“swellings”). Radioactivity appeared first in “endings” and then in progressively larger and larger profiles of “swellings”. It appeared that newly arrived granules were found close to the limiting membrane of the nerve swelling and that as time progressed they moved deeper and deeper into the swelling. On the basis of the results, suggestions were made for an anatomical explanation of the readily-releasable pool of hormone which has been demonstrated pharmacologically.
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    URL: http://dx.doi.org/10.1007/BF00225108
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    Correlations between brain catecholamines, neurosecretion, and serum corticoid levels in osmotically stressed mallard ducks (Anas platyrhynchos) (1975)
    Springer
    Cell & tissue research 161 (1975), S. 277-283 
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    ISSN: 1432-0878
    Keywords: Neurosecretion ; Osmotic stress ; Serum corticoid levels ; Catecholamine depletion ; Anas platyrhynchos (Aves)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The effects of depleting brain catecholamines with a combined treatment of reserpine and α-methyl-p-tyrosine on serum corticosterone levels and release of immunoreactive neurophysin from the median eminence, in osmotically stressed and unstressed mallard ducks, were studied. Corticoid levels in salt loaded birds were more than three times that of unstressed birds. The combined treatment of reserpine and α-methyl-p-tyrosine significantly decreased the concentration of brain monoamines in all experimental groups and raised serum corticoid levels in non-stressed birds to the same level found in the osmotically stressed animals. Immunoreactive neurophysin in the zona externa of the median eminence was depleted in all birds subjected to either osmotic stress and/or reserpine treatment but not in unstressed control birds. These preliminary data indicate that catecholamines may exert an inhibitory influence on both ACTH release from the anterior pituitary and neurophysin from the median eminence and that these two events may in some way be interrelated in the duck.
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    URL: http://dx.doi.org/10.1007/BF00220374
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    Neurosecretion in the sinus gland of the fiddler crab, Uca pugnax (1975)
    Springer
    Cell & tissue research 165 (1975), S. 129-133 
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    ISSN: 1432-0878
    Keywords: Neurosecretion ; Sinus gland ; Eyestalk ; Ultrastructure ; Uca
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The ultrastructure of the sinus gland of the fiddler crab, Uca pugnax, was investigated and found to be similar to that in other crustaceans. Five types of neurosecretory axon terminals were tentatively identified on the basis of the size, shape, and electron density of granules within the axons. Release of neuro-secretory material appears to be by exocytosis.
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    Additional evidence for the binding of calcium ions to elastin at neutral sites (1974)
    Springer
    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)
    Springer
    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)
    Springer
    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)
    Springer
    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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  • 96
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    Increased bone microhardness in fluoride treated rats (1974)
    Springer
    Calcified tissue international 15 (1974), S. 45-54 
    Details
    ISSN: 1432-0827
    Keywords: Bone ; Fluoride ; Microhardness ; Mineralization ; Strength
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract Microhardness was measured in sampling sites in the tibial diaphysis of control rats that received less than 1 ppm fluoride in the drinking water, and experimental rats that received 30, 90 and 120 ppm fluoride in the drinking water for 17 days. The latter dose was toxic, as evidenced by a decreased final body weight in this group. By means of tetracycline labelling, it was possible to measure bone hardness in four zones of increasing bone age: I) 3 days, II) 8 days, III) 13 days and IV) 22 days. Zones I through III represented bone formed during fluoride treatment, and Zone IV bone formed before fluoride treatment. In the control group, microhardness increased from Zone I to II, probably because mineral concentration was relatively low in Zone I, and remained constant thereafter. In the 90 and 120 ppm fluoride-treated groups, maximum microhardness was not achieved until Zone III. This delay was probably due to the fact that fluoride in large doses inhibits the rate of mineralization. In the 30 ppm fluoride-treated group, there was no delay in achievement of maximum microhardness; microhardness values in Zones I and III were greater than those in control animals, and microhardness in Zone III was higher than that in Zone IV. These results show that: 1) bone microhardness is increased in bone formed during fluoride treatment in rats given 30 ppm fluoride in the drinking water, 2) toxic doses of fluoride delay, but do not prevent achievement of normal maximum microhardness, and 3) changes in microhardness are seen only in bone formed during fluoride treatment.
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    URL: http://dx.doi.org/10.1007/BF02059042
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  • 97
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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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02059044
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  • 98
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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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  • 99
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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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  • 100
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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.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02059055
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