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1.
2.
Synergistic stimulation of the Ca2+ influx in rat hepatocytes by glucagon and the Ca2+-linked hormones vasopressin and angiotensin II 总被引:10,自引:0,他引:10
Glucagon was added to isolated rat hepatocytes, either alone or together with vasopressin or angiotensin II, and the effects on the initial 45Ca2+ uptake rate were investigated. Addition of glucagon alone which increased cyclic AMP content of the cells slightly increased the initial 45Ca2+ uptake rate. When glucagon was added together with vasopressin or angiotensin II--both of which when added separately increase the initial 45Ca2+ uptake rate but did not affect the cellular content of cyclic AMP--the measured initial 45Ca2+ uptake rate was larger than the sum of that seen with each hormone alone. This indicates that glucagon and Ca2+-linked hormones synergistically enhanced the Ca2+ influx in rat hepatocytes. These effects of glucagon can be mimicked by dibutyryl cyclic AMP or forskolin, suggesting that cyclic AMP augments both the resting Ca2+ and the vasopressin- or angiotensin II-stimulated influx. Measurement of the initial 45Ca2+ uptake rate as a function of the extracellular Ca2+ concentration indicated that the increase in the Ca2+ influx resulting from single or combined glucagon and vasopressin administration occurred through a homogeneous population of Ca2+ gates. These hormones were found to raise both the apparent Km for external Ca2+ and the apparent Vmax of the Ca2+ influx. The maximal increase in these two parameters was observed when the two hormones were added together. This suggests that glucagon and vasopressin synergistically stimulate the same Ca2+ gating mechanism. The dose-response curves for the action of glucagon or vasopressin applied in the presence of increasing concentrations of vasopressin or glucagon, respectively, showed that each hormone increases the maximal response to the other without affecting its ED50. It is proposed that glucagon and the Ca2+-linked hormones control the cellular concentration of two intermediates which are both necessary to allow Ca2+ entry into the cells. 相似文献
3.
Summary Amo 1618 inhibits germination and root growth of Lentil seedlings in the dark and in the light, with some symptoms of toxicity; CCC has no effect.Both CCC and Amo 1618 inhibit the catalase activity of a lentil root extract.Increasing concentrations of Amo 1618 progressively increase the activity of peroxidase and IAA-oxidase in vivo; the catalase activity remains unchanged.The effect of Amo 1618 on root growth can thus be explained by a diminished auxin level mediated by an increased auxin catabolism.The effect of Amo 1618 and that of kinetin on root growth and enzymes are parallet. Gibberellic acid has an opposite effect on auxin catabolism.
Une partie de ce travail a fait l'objet du mémoire de Licence de J. L. et a été réalisée au Laboratoire de Biochimie végétale de l'Institut de Botanique de Liège. 相似文献
Une partie de ce travail a fait l'objet du mémoire de Licence de J. L. et a été réalisée au Laboratoire de Biochimie végétale de l'Institut de Botanique de Liège. 相似文献
4.
Summary A histological, histochemical and ultrastrucutral study of the pars intercerebralis (PI) has been made in Locusta migratoria.
The acellular neural lamella is made up of an elastic tissue and collagen fibrils. The cells of the perilemma contain numerous lysosome structures and lipid granules.Three different types of neurosecretory cells (NSC A, B and C) have been distinguished in the PI associated with giant neurons.The cells termed A and B seem not to have an activity cycle during the two last larval instars. At the moment of sexual maturity the NSC A show an important accumulation of neurosecretory material and their number increases at the expense of the NSC B. The NSC A, which are characterized by a highly developped endoplasmic reticulum, contain numerous secretory granules which appear to be individualized in the Golgi complex in three different ways. The NSC B, with a reduced endoplasmic reticulum and an almost quiescent Golgi complex, contain abundant lysosome structures and more seldom some neurosecretory granules. In fact, the study of the fine structure shows different intermediate types, linking in a continuous way typical A cells and typical B cells. NSC A and NSC B might correspond to two opposed stages of secretory activity of one single cell type: the A cell representing the activity stage and the B cell the quiescent stage.NSC C show an accumulation of their neurosecretory products in relation to metamorphosis and sexual maturity. Ultrastructural evidence confirms their neurosecretory activity.A mode of regulating neurosecretion in NSC A and B by internal catabolism of the secretion and formation of lysosome like structures is discussed in the present paper.The giant neurons, which are surrounded by a glial envelope (trophospongium), contain several dense granules originated from Golgi complex. 相似文献
5.
The human cystatin C gene (CST3), mutated in hereditary cystatin C amyloid angiopathy,is located on chromosome 20 总被引:9,自引:4,他引:5
Magnus Abrahamson M. Quamrul Islam Josiane Szpirer Claude Szpirer Göran Levan 《Human genetics》1989,83(3):223-226
Summary Hereditary cystatin C amyloid angiopathy has recently been shown to be caused by a point mutation in the cystatin C gene. To determine the chromosomal localization of the gene, 20 human-rodent somatic cell hybrids and a fulllength cystatin C cDNA probe were used. Southern blot analysis of BamHI digested cell hybrid DNA revealed that the probe recognizes a 10.6 kb human specific fragment and that this fragment cosegregates with human chromosome 20. Therefore, the human cystatin C gene (CST3) was assigned to chromosome 20. 相似文献
6.
7.
Josiane Arnaud Pierre Bourlard Bernard Denis Alain E. Favier 《Biological trace element research》1996,53(1-3):129-136
This study was carried out to assess manganese (Mn) status after an acute episode of myocardial infarction. Plasma and erythrocyte
Mn concentrations were measured from admission to hospital to day 15 postadmission in 21 patients suffering from acute myocardial
infarction and in three control groups. The determination of Mn in these biological fluids was performed by electrothermal
atomic absorption spectrometry. Plasma Mn was higher (p<0.01) and erythrocyte Mn was similar in the acute myocardial infarction group compared to healthy age-matched control group.
Plasma and erythrocyte Mn remained unchanged during the 2 wk after acute myocardial infarction and were not correlated to
enzyme activities. A decrease of erythrocyte Mn with age, expressed in nmol/L, was noted (p<0.02). These results suggest that plasma and erythrocyte Mn do not provide an indication of myocardial damage. Nonetheless,
Mn status in elderly merits further attention. 相似文献
8.
Josiane Girardie Adrien Girardie Alain Van Dorsselaer Odile Sorokine Serge Geoffre Michel Hospital Gilles Precigoux 《Journal of peptide science》1995,1(5):311-318
An original insect neurohormone of 65 residues was synthesized by the solid-phase methodology using t-Boc strategy and Boc-Val-PAM–resin. The purification, conducted by several steps of liquid chromatography having mass, polarity or charge as separative criteria, yielded the product with the correct molecular weight of 6922 Da determined by mass spectrometry. The synthetic peptide had both the same affinity for the antinative neurohormone serum and the same biological activity as the native neurohormone. 相似文献
9.
Charles Coudray Sylvie Pucheu François Boucher Josiane Arnaud Joël de Leiris Alain Favier 《Biological trace element research》1994,41(1-2):69-75
The hypothesis that oxygen-derived free radicals play an important role in myocardial ischemic and reperfusion injury has received a lot of support. In the presence of catalytic amounts of transition metals such as iron, superoxide anions, and hydrogen peroxide can be transformed into a highly reactive hydroxyl radical °OH (Haber-Weiss reaction). In view of this, we have undertaken this study to investigate whether iron is involved in the reperfusion syndrome and therefore could aggravate free radicals injury. Coronary effluent iron concentrations and cardiac cytosolic iron levels were evaluated in rat hearts subjected to an ischemia/reperfusion sequences. In the case of total ischemia, iron concentration in coronary effluents peaked immediately in the first sample collected upon reperfusion. However, in the case of partial ischemia, iron concentration in coronary effluents peaked rather exclusively during ischemia period. Cardiac cytosolic iron level augmented significantly after 30 min of total ischemia and non significantly in the other ischemia protocols compared to perfused control hearts. It also appears that the iron released is not protein-bound, and could therefore have a marked catalytic activity. The results of the present study suggest that in the oxygen paradox, iron plays an important role in inducing alterations during reoxygenation. 相似文献
10.
Marie J. Richard Veronique Ducros Michel Rorêt Josiane Arnaud Charles Coudray Michèle Fusselier Alain Favier 《Biological trace element research》1993,39(2-3):149-159
In six chronic dialyzed uremic patients, an intravenous sodium selenite (Se 50 μg during 5 wk and then 100 μg) and zinc gluconate
(Zn 5 mg) supplementation was performed during 20 wk at each dialysis session three times weekly. Before supplementation,
plasma Se and Zn, plasma and erythrocytes (RBC) antioxidant metalloenzymes glutathione peroxidase (GPX), and superoxide dismutase
(SOD) were significantly decreased, whereas lipid peroxidation (as thiobarbituric acid reactants TBARs) was increased. To
obtain a significative change in plasma selenium, we had to use an Se dose of 100 μg/dialysis session. Then, treatment-increased
plasma Se (from 0.58 ±0.09 to 0.89±0.16 μmol/L) led to a repletion of RBC-GPX (from 29.6±6 to 43±5.8 U/g Hb) and increased
plasma GPX levels (from 62±13 to 151±43 U/L). Plasma Zn and RBC-SOD did not vary significantly. The change of TBARs was not
observed between wk 1 and 4. They decreased significantly between wk 4 (4.80±0.21μmol/L) and wk 20 (4.16±0.26 μmol/L). We
noted a low correlation between TBARs and plasma GPX. A strong correlation was observed between Se and plasma GPX. The reversal
of Se deficiencies should reduce oxidative damage observed in these patients. 相似文献