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  • Calcium  (7)
  • propranolol  (4)
  • Springer  (11)
  • American Physical Society
  • Annual Reviews
  • National Academy of Sciences
  • Springer Science + Business Media
  • 1980-1984  (11)
  • 1980  (11)
Collection
Publisher
  • Springer  (11)
  • American Physical Society
  • Annual Reviews
  • National Academy of Sciences
  • Springer Science + Business Media
Years
  • 1980-1984  (11)
Year
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 32 (1980), S. 45-53 
    ISSN: 1432-0827
    Keywords: Dentin ; Periodicity ; Allometry ; Calcium ; Sulfur
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary We have described differences in the aspects of biological rhythms for calcium and sulfur deposition on the labial and lingual sides of the growing rabbit incisor, where growth occurs along a spiral axis. The calcium oscillations appear to be smoother on the labial side than on the lingual side. The lingual side is characterized by high-frequency rhythms with high amplitudes which possess the greatest percent of the power (Fourier analysis). These observations also reflect a difference in behavior of the mean Ca concentration across the labial and lingual sides. Sulfur rhythms on the labial side have higher amplitudes than those on the lingual side, but systematic differences in distribution of power between high and low frequencies is not as pronounced as in the case of Ca. The differences in Ca rhythms reflect differences in the growth rates of incisors on either side of the spiral axis. The labial side grows slightly faster than the lingual side, and its odontoblasts secrete Ca along the spiral axis and toward the pulp cavity at the same time. Thus the resultant direction of growth is more nearly opposite the extension of the occlusal end on the labial side, and Ca is consequently deposited over a wider area relative to that on the lingual surfaces. On the lingual side, Ca is deposited within a more limited area, and growth must therefore be continuous at high frequencies. The distribution of Ca on both sides of the tooth reflects these differences in growth rate and periodicity in two ways. First, given a unit area of tooth, the calcium concentration on the labial side is less than that of the lingual side. Second, whereas the calcium concentration on the labial side declines rapidly from the enamel-dentin junction to the pulp cavity, it is uniformly high across the lingual side because its growth is more continuous at high frequencies.
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 32 (1980), S. 29-44 
    ISSN: 1432-0827
    Keywords: Rabbit ; Dentin ; Calcium ; Sulfur ; Periodicity ; Circadian ; Ultradian
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary We have identified a variety of biological rhythms involved in the apposition and mineralization of dentin in the rabbit incisor. Animals were injected during the day or night with lead acetate at 2-week intervals—to provide biological time markers in forming dentin—and transverse undecalcified sections of the lower incisors were prepared for electron microprobe analysis. The positions of the lead markers were identified, and the continuous distribution of calcium and sulfur was measured at 1 µm intervals between the markers. In thin sections stained with hematoxylin after decalcification, the widths of a series of structural increments (bands) were measured with an ocular micrometer. Fourier analysis of the data revealed spectra of structural and compositional rhythms with a range of periodicities which extended from a matter of hours [ultradian (〈24 h)] to days [infradian (〉24 h) and circadian (approximately 24 h)]. The structural and compositional rhythms appeared to be independent to the extent that they did not necessarily have the same periods, or amplitudes. Nor were there simple phase relationships between all of the rhythms. At some times, Ca and S fluctuations are inversely proportional (180° out of phase), but in other cases they are directly proportional or out of phase by varying degrees other than 180°. The analyses thus suggest that calcium and sulfur deposition (representing mineral and glycosaminoglycan deposition, respectively) are not simply inversely proportional, and that the hematoxylin-stained structural increments did not solely reflect differences in the distribution of the mineral components in dentin.
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  • 3
    ISSN: 1432-0827
    Keywords: Bone cells ; Cyclic AMP ; Calcium ; Ascites fluid resorptive protein
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The effects of a bone resorptive protein isolated from human cancer ascites fluid on bone cell calcium and cyclic AMP were studied with fetal rat cells. The osteoclast-activating factor increased bone cell calcium uptake at 37°C and 4°C with no direct effects on calcium efflux. Concentrations of the resorptive factor that increased in vitro bone resorption and cell calcium uptake had no effect on cyclic AMP. The effects of the protein on calcium uptake were not specific for bone cells, and large increases were also observed in isolated fetal rat skin cells. These studies suggest that increases in the permeability of the cell membrane to calcium are involved in the mechanism of action of the ascites fluid resorptive protein.
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  • 4
    ISSN: 1432-0827
    Keywords: Hydroxyapatite ; Dissolution ; Pyrophosphate, Diphosphonates ; Calcium ; Phosphate
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary Pyrophosphate and diphosphonate ions have been said to diminish the dissolution of hydroxyapatite crystals, because they lower the equilibrium concentrations of calcium and phosphate ions in the bulk solution around hydroxyapatite crystals in a closed system. However, in a closed system these effects are not necessarily due to an effect on dissolution alone. In this paper we have used a continuous flow system to study the effects of pyrophosphate and two diphosphonates, ethane-1-hydroxy-1,1-diphosphonate and dichloromethane diphosphonate, on the dissolution of hydroxyapatite. All three compounds decreased markedly the rate of dissolution of hydroxyapatite as well as the exchangeable pools of calcium and phosphate ions around the cystals.
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  • 5
    ISSN: 1432-0827
    Keywords: 1α-Hydroxy vitamin D3 ; 1,25-Dihydroxyvitamin D3 ; Calcium ; Transport ; Intestine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The timed sequence of events following the oral administration of 1α-hydroxy vitamin D3 (1αOHD3) to rachitic chicks was compared to that following a comparable dose of 1α,25-dihydroxyvitamin D3 (1,25(OH)2D3). RNA polymerase activity was maximally increased 20% by 1αOHD3 within 1 to 2 h and returned to control values after 8 h. Alkaline phosphatase activity was stimulated by 4 h and was maximal (3- to 5-fold increase) at 24 h. Calcium binding protein (CaBP) was detected initially within epithelial cells at the proximal end of the villus (just above the crypt) 6 to 8 h after 1αOHD3 administration, in epithelial cells lining the proximal half of the villus by 24 h, and in epithelial cells along nearly the entire villus by 48 h. At no time did goblet cells contain CaBP. Serum calcium concentrations were significantly elevated in 2 h and maximal by 12 h (an increase of 3.6 mg/dl). Calcium accumulation by the intestinal mucosa in vitro was increased by 6 to 8 h and maximal (60% increase over controls) at 24 h. Phosphate accumulation by the intestinal mucosa in vitro was increased by 6 h and maximal (105% increase over controls) between 8 and 24 h. 1,25(OH)2D3 increased CaBP and calcium accumulation by 4 h, 2 h sooner than did 1αOHD3. 1,25(OH)2D3 decreased serum calcium levels and increased serum phosphate levels at 2 h unlike 1αOHD3. No difference in the effects of these compounds on alkaline phosphatase activity, RNA polymerase activity, and phosphate accumulation could be demonstrated. These results are consistent with the possibility that 1αOHD3 may not require conversion to 1,25(OH)2D3 for all of its biological effects.
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 30 (1980), S. 27-34 
    ISSN: 1432-0827
    Keywords: Ultrastructure ; Calcium ; Cartilage ; Vesicles
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The potassium pyroantimonate technique was utilized for the selective subcellular localization of calcium in the mandibular condylar cartilage of 1-day-old rats. Electron dense calcium pyroantimonate precipitates were localized principally in mitochondria and at the cell membrane of the chondrocytes. In addition, small intracellular vesicles 0.1–0.2µm in diameter were observed in proximity to the cell membrane of chondrocytes of the mid-hypertrophic zone. The results suggest that these vesicles were being extruded from the cell into the extracellular matrix. Energy-dispersive analysis by X-rays confirmed that calcium is the principal cation of the electron-dense precipitates.
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  • 7
    ISSN: 1432-1041
    Keywords: oxprenolol ; propranolol ; sotalol ; slow release preparation ; plasma level ; exercise tachycardia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary Observations were made in 5 healthy subjects who exercised before and 1, 3, 6, 8 and 24 h after the oral administration on separate occasions of 160 mg oxprenolol, 160 mg slow release oxprenolol, 160 mg long acting propranolol and 400 mg sotalol. Blood samples were obtained before and at 1, 2, 3, 6, 8, 10 and 24 h after drug administration and assayed for drug concentration. Although the plasma concentration of oxprenolol after S. R. oxprenolol was significantly less at 1 and 2 h and significantly greater at 24 h than after conventional oxprenolol, there was little difference between the effects of the two drugs on an exercise tachycardia. The plasma level of propranolol and the reduction in an exercise tachycardia after L. A. propranolol increased slowly to reach a peak at 6 h and then declined gradually to 24 h. The maximum plasma concentration and effect after sotalol occurred at 3 h and then declined with an elimination half-life of 12.1 h. At 24 h the percentage reduction in an exercise tachycardia was 8.3±2.5 after oxprenolol, 10.0±2.3 after S. R. oxprenolol, 18.0±3.2 after L. A. propranolol and 14.7±3.4% after sotalol.
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 17 (1980), S. 349-354 
    ISSN: 1432-1041
    Keywords: propranolol ; radioreceptor assay ; beta-adrenoceptor antagonists ; lung membranes ; plasma level ; healthy volunteers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary A radioreceptor assay (RRA) recently developed in this laboratory for beta-adrenoceptor antagonists in plasma was evaluated in normal volunteers and compared with a radioimmunoassay (RIA) for propranolol. The RRA depends upon the ability of beta-adrenoceptor antagonists to compete with a radiolabelled ligand for beta-adrenoceptor binding sites on lung membranes. Unlike other assays, it measures biologically active drugs including active metabolites of the parent compound. In volunteers given a single oral dose of (±)-propranolol, considerable differences between the two assay methods were demonstrated. In other experiments this difference was shown to relate to the RIA's sensitivity to the inactive (+)-isomer of propranolol and possibly to inactive metabolites. The facility of the RRA in measuring plasma levels of several other non-selective beta-adrenoceptor antagonists was also demonstrated. By employing (−)-propranolol as the standard in the RRA, all of these drugs can be directly compared with a single and relatively simple assay technique.
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  • 9
    ISSN: 1432-1041
    Keywords: papaverine ; propranolol ; pindolol ; hypertension ; isoprenaline ; haemodynamic effects ; blood pressure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The influence of two β-adrenoceptor antagonists, propranolol and pindolol, on the haemodynamic effects of papaverine, isoprenaline and noradrenaline was investigated in 9 male patients with first degree essential hypertension. Propranolol and pindolol were given according to a doubleblind, crossover scheme. Heart rate and blood pressure were measured before and after each treatment. Propranolol 670 µg/kg i. v. reduced the supine and standing systolic blood pressures by 2.3% and 1.6%, respectively. Similarly, the intravenous administration of pindolol 35 µg/kg reduced supine and standing systolic blood pressure by 5.5% and 8.3% respectively (clinically insignificant). Neither drug affected diastolic blood pressure. Following propranolol, there were moderate reductions in supine and standing heart rates, respectively by 24% and 20% (p〈0.001). Similarly, but to a lesser extent, pindolol reduced supine and standing heart rate by 12% and 17% (p〈0.001). The effects of papaverine, which, at 1.5 mg/kg i. v. reduced systolic blood pressure by 5–10% and increased heart rate by 8–15%, were not significantly influenced by the β-blockers. The blood pressure and heart rate responses to isoprenaline, on the other hand, were attenuated or inhibited by both β-blockers. While the β-blockers inhibited the β-adrenoceptor component of noradrenaline, the pressor component of noradrenaline, which is mediated through the α-adrenoceptors, was not influenced by propranolol, but was inhibited after pindolol. It is concluded that pindolol differs qualitatively from propranolol in that it inhibited both the α-and β-adrenoceptor effects of noradrenaline.
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  • 10
    ISSN: 1432-1041
    Keywords: propranolol ; glucose ; schizophrenia ; glucose tolerance test ; blood glucose ; plasma propranolol
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary No correlation was found between blood glucose and simultaneous measurements of plasma propranolol concentration in patients with schizophrenia, on a daily dose of 80 mg to 1800 mg of propranolol as an adjunct to phenothiazine medication. The Glucose Tolerance Test (GTT) in ten patients on propranolol and phenothiazines did not differ significantly from those of a matched control group on phenothiazine alone. Two patients with mild diabetes showed no significant change in their GTT after stopping propranolol. These observations accord with the view that relatively high doses of propranolol as an adjunct to phenothiazine medication in schizophrenia are safe from the standpoint of glucose metabolism. This does not apply to the insulin dependent diabetic who is in danger of severe hypoglycaemia when glycogenolysis is blocked by propranolol.
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