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  • Articles: DFG German National Licenses  (2)
  • Electronic Resource  (2)
  • 1,25-dihydroxyvitamin D  (1)
  • Acidosomes  (1)
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  • Articles: DFG German National Licenses  (2)
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  • Electronic Resource  (2)
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  • 1
    Electronic Resource
    Electronic Resource
    Secondary hyperparathyroidism with 1,25-dihydroxyvitamin D deficiency and pseudohypoparathyroidism in childhood: Relationship between plasma 1,25-dihydroxyvitamin D and parathyroid hormone levels and urinary cyclic AMP response to exogenous PTH (1981)
    Springer
    European journal of pediatrics 135 (1981), S. 267-271 
    Details
    ISSN: 1432-1076
    Keywords: Pseudohypoparathyroidism ; Pseudopseudohypoparathyroidism ; 1,25-dihydroxyvitamin D
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract In order to clarify the complex interrelationship between serum calcium, 1,25-dihydroxyvitamin D (1,25(OH)2D), and parathyroid hormone (PTH), and the urinary excretion of cyclic AMP (cAMP) in response to exogenous PTH in pseudohypoparathyroidism (PHP) and related diseases, we investigated 3 patients with parathyroid disorders before and after treatment with 1α-hydroxyvitamin D3 (1α-OH-D3). Low plasma 1,25(OH)2D before treatment increased after giving 1α-OH-D3 (0.1 μg/kg/day), where-as high plasma PTH measured by the C-terminal assay (C-PTH) decreased in all 3. No response in urinary cAMP was found before or after treatment in 2 patients with PHP type I, despite the fall of plasma C-PTH. However, in one patient with extremely high plasma C-PTH but normal N-PTH (measured by a homologous radioimmunoassay using 1–34 human PTH), urinary cAMP response to exogenous PTH was increased after treatment with 1α-OH-D3. We suggest that he had pseudopseudohypoparathyroidism (PPHP) with Albright's hereditary osteodystrophy and a partial deficiency of renal 1α-hydroxylase. In this patient secondary hyperparathyroidism is thought to be due to 1,25(OH)2D deficiency, and the decreased responsiveness to exogenous PTH before treatment due to excess PTH occupying renal receptors.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00442101
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Acidification of the young phagosomes ofParamecium is mediated by proton pumps derived from the acidosomes (1997)
    Springer
    Protoplasma 196 (1997), S. 12-20 
    Details
    ISSN: 1615-6102
    Keywords: Acidosomes ; Concanamycin B ; Phagosomes ; Proton pumps ; Paramecium ; Vacuolar ATPase
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Although it is generally accepted that phagosome acidification is induced through the activity of a vacuolar proton pump (V-ATPase) present on the phagosome membrane, exactly how these pumps are delivered to the phagosomes is not well understood. To study this question inParamecium, it was necessary to first show that an authentic V-ATPase was present on their phagosomal membranes. Three antibodies raised against V-ATPases or their subunits were each found to label one or two large digestive vacuoles (DVs) inParamecium multimicronucleatum when immunofluorescence microscopy was used. Using horseradish peroxidase immunocytochemistry to increase sensitivity, about 10 DVs were shown to contain a V-ATPase. In high magnification images and cryoultramicrotomy these proton pumps were found to be located on the acidosomes, suggesting the vacuolar proton pumps on the DVs originate from the acidosomes. The authenticity of the V-ATPase was further confirmed by its sensitivity to cold temperature and to the V-ATPase specific inhibitor, concanamycin B, which at 10 nM doubled the t1/2 for vacuole acidification. Thus, we conclude that (1) acidosomes and some DVs ofParamecium have a bona-fide concanamycin B-sensitive and cold-sensitive V-ATPase, (2) the V-ATPase is delivered to the young DVs during acidosome fusion, and (3) the V-ATPase is involved in vacuole acidification. Finally, we have now determined thatParamecium has two immunologically related V-ATPases that are involved in two very different functions, (1) the acidification of phagosomes and (2) fluid segregation in the contractile vacuole complexes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01281054
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    Paper (German National Licenses)
    Fulltext
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