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221.
Cloning and molecular characterization of two genes encoding adhesion proteins involved in Trichomonas vaginalis cytoadherence 总被引:11,自引:2,他引:9
222.
Cells were subjected to a range of 45Ca2+ influx loads with A23187. We measured cell 45Ca2+ with time and A23187 dose, and the apparent 45Ca2+ influxes (≡“J(in,app)”) at Ca2+ steady state. We also measured endogeneous exchangeable and total cell Ca2+, which were 50 and 17–220 μM respectively. The effects of A23187 and Ca2+ on cell ATP, swelling, net Cl− permeability, and cell morphology were measured. These were modest and do not affect our conclusions.J(in,app) 3 × 10−4 [A23187]2.9·[Ca2+(o)]μmoles/l·min with 92–552 μM [Ca2+(o)] (≡ external Ca2+ concentration) and 0–7 μM A23187. J(in,app) was increased an order of magnitude by vanadate and is probably much less than the true influx. The least unlikely explanation found for the high [A23187] exponent, 2.9, was that most of the Ca2+ crossing the membrane is expelled by the pump before it can move deeper into the cell.Calcium pumping increased rapidly in response to increased influx, but the steady state cell 45Ca2+ was approximately proportional to J(in,app) rather than approximately constant between 10 and 120 μmoles/l·min with 184 μM [Ca2+(o)]. This is not the result expected from a simple feedback mechanism.At high A23187 doses the pump appears fully activated resulting in a linear relation between cell/medium 45Ca2+ and [A23187]−2. From the plot we calculated α≡free/total exchangeable Ca2+ = 0.38 ± 0.08 (n = 3) and a maximum pump rate, “Pmax” = 78 μmole/l·min. Pmax is underestimated insofar as J(in,app) is less than the true influx. 相似文献
223.
Jean Théodoridès 《Origins of life and evolution of the biosphere》1984,13(3-4):339-342
The Gregarinia, all parasitic in invertebrates have appeared in marine hosts (Polychaeta). The most primitive are the Archigregarinida (Selenidium) which are intestinal parasites. The Eugreganida (intestinal or coelomic) are found in various marine invertebrates as well as in terrestrial or fresh water arthropods. The Neogregarinida which parasitize only insects have a very reduced number of spores compensated by a schizogony (merogony). The Gregarinia constitute a perfect example of a concomitant evolution between a group of parasites and their hosts. 相似文献
224.
Jacques Dornand Jean-Claude Bonnafous Jean Favero Agnés Gartner Jean-Claude Mani 《Biochimica et Biophysica Acta (BBA)/Molecular Cell Research》1984,804(4):398-403
It is now well established that human lymphoblastoid cell lines showing immaturity characters display ecto-5′-nucleotidase activities lower than normal levels. A recent paper (Sun, A.S., Holland, J.F. and Ohnuma, T. (1983) Biochim. Biophys. Acta 762, 577–584) mentioned that this phenomenon resulted from the presence of a 5′-nucleotidase inhibitor in these cell lines. We demonstrate here that the use of 5′-[3H]AMP as a substrate, and inadequate analysis of the products formed, led them to a misinterpretation. [3H]Adenosine derived from 5′-[3H]AMP hydrolysis was further transformed into [3H]inosine by the adenosine deaminase activity of the leukemic cell lines tested; [3H]inosine was precipitated with the excess substrate and was not taken into account in the ecto-5′-nucleotidase determination, which led the authors to confuse this adenosine deaminase activity with a 5′-nucleotidase inhibitor. We did not observe 5′-nucleotidase inhibition by leukemic cell cytosol when convenient assay methods were used and showed that the presence of such an inhibitor remains to be established. 相似文献
225.
Luc Cynober Jean-Louis Auget Jean Agneray Ohvanesse G. Ekindjian 《Biochemical and biophysical research communications》1984,123(2):535-542
2-deoxyglucose uptake rates at low sugar concentrations (less than 500 μM) appeared to be lower than those predicted by the Michaelis-Menten model which correctly described higher concentrations. This phenomenon which we will call concentration-dependent transport lag, was also observed for L-glucose uptake which suggest that this phenomenon is carrier-independent. A model involving the perimembrane space is developed which, for L-glucose, gives k1 = 0.931 ± 0.072 × 10?6 l. mg protein?1. minute?1, k2 = 2.97 ± 0.19 × 10?7 l. mg protein?1. minute?1 and So = 88,8 ± 4,3 μM; where k1 is the diffusion constant in the cell membrane, k2 is the diffusion constant in the perimembrane space and So the sugar concentration required in the external medium in order to provide an équivalent sugar concentration in the transport carrier area. 相似文献
226.
Jean Morisset 《Regulatory peptides》1984,10(1):11-22
The increases in DNA synthesis and total DNA content after caerulein treatment support the trophic effect of this CCK analog on the pancreas. Over a 15 day caerulein treatment, pancreatic growth plateaued after 5 days and somatostatin is believed to be responsible for this phenomenon. The present study was undertaken to test this possibility. Rats were treated for 2 or 4 days with caerulein (1 μg · kg?1), somatostatin antiserum plus caerulein or caerulein plus somatostatin (600 μg · kg?1). Caerulein increased all parameters studied after 2 and 4 days; pancreatic hyperplasia was established after 2 days. The somatostatin antiserum significantly enhanced the effect of caerulein, especially on DNA synthesis and contents after 2 and 4 days. The trophic effect of caerulein was significantly reduced by somatostatin dramatically so with respect to hyperplasia. The effects of the somatostatin antiserum and those of somatostatin on stimulated pancreatic growth support the hypothesis that somatostatin may be considered an endogenous growth inhibitory factor for the pancreas. 相似文献
227.
Summary The administration of progesterone to ovariectomized rats induces an increase in the volume density (Vv) of the mitochondria and the appearance of giant mitochondria in the uterine glandular cells. This experimental model, including a stereological analysis, allowed us to investigate and quantify a direct effect of progesterone on a well-defined cellular structure without the intervention of estrogen in a priming phase. Synthetic compounds, promegestone, gestrinone and RU 38486, were tested in this model either in place of progesterone or simultaneously with progesterone. The potent progestomimetic activity of promegestone was confirmed by the proliferation of giant mitochondria and a high Vv value for the mitochondria, the two other compounds being inactive even at higher doses. At lower doses, gestrinone and RU 38486 partially inhibit the action of progesterone and at higher doses they both show a complete antagonist effect by preventing the development of the mitochondria. 相似文献
228.
An indirect enzyme-linked immunoadsorption assay (ELISA) was developed for cytochrome c3 using antisera to the cytochromes fromDesulfovibrio africanus Benghazi, Desulfovibrio vulgaris Hildenborough andDesulfovibrio salexigens British Guiana. The ELISA system was used to test for cross-reactions between these antisera and the heterologous antigens. In contrast to previous experiments using the Ouchterlony technique, all of the cytochromes c3 tested exhibited some degree of cross-reaction. Considerable variation was seen in cross-reactions for cytochromes c3 from differing strains ofD. desulfuricans. This observation raises questions about the taxonomic relatedness of these strains. No cross-reaction was seen with eukaryotic cytochrome c or withD. vulgaris cytochrome c553. The data demonstrate that cytochrome c3 is capable of undergoing nonprecipitating cross-reactions, and thus may not be as immunologically unique as was once thought.Abbreviations ELISA
Enzyme-linked immunoadsorption assay 相似文献
229.
230.
Découverte de microfaunes de l'Albienmoyen et supérieur dans la vallée de Joux (Jura Vaudois,Suisse)
The discovery of Foraminifera and Ostracodesin the dark green, sandy-glauconitic marl clay in the Joux Valley (in the Vaudois Jura) suggests to date these sediments Middle and Upper Albian. The Ostracode associations are similar to those found in the Paris Basin, but different from those which characterize the subalpine region. 相似文献