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Biomedical subjects

R Fuchs

Publications and source records attributed to R Fuchs.

At least 91 records · Page 5Linked to original sources
PubMed1985

Effects of 1 alpha,25-dihydroxycholecalciferol on sodium-ion translocation across chick intestinal brush-border membrane.

By utilizing isolated brush-border vesicles, Na+ transport across the luminal membrane of chick small intestine was found to be a composite of (i) a saturable (Km 10mM-Na+) amiloride-sensitive Na+/H+ antiport and (ii) a potential-sensitive conductive pathway. No evidence was obtained for the existence of a Na+/Cl- symport system. With the exception of the duodenum, luminal Na+ transfer in the entire small intestine was subject to regulation by vitamin D. Repletion of vitamin D-deficient chicks with 1 alpha,25-dihydroxycholecalciferol [1 alpha,25(OH)2D3] significantly decreased net Na+ uptake by isolated membrane vesicles (by approximately 30%). The sterol suppresses the conductive pathway (25-45% inhibition) as well as the Na+/H+ antiport system. Kinetic analysis of the latter revealed that 1 alpha,25(OH)2D3 altered Vmax (from 12.9 to 4.8 nmol of Na+/20s per mg of protein), but did not change Km. Diminution of Na+ transfer, entailing an increase in the electrochemical transmembrane Na+ gradient, provides an explanation of the simultaneously observed stimulatory action of 1 alpha,25(OH)2D3 on Na+-gradient-driven solute transport in chick small intestine. Indirect evidence was obtained that the luminal plasma membrane of chick small intestine displays a definite H+ permeability that is positively affected by 1 alpha,25(OH)2D3.

Amiloride↗
PubMed1985

Levamisole circumvents inhibition of lymphocyte activation imposed by uremic serum.

Uremic serum inhibits thymidine incorporation of phytohemagglutinin-stimulated lymphocytes originating in normal individuals. In this study the effect of levamisole on such inhibition was investigated. Preincubation with a wide range of levamisole concentrations resulted in complete prevention of the inhibitory effect imposed by uremic serum on thymidine incorporation. We would like to suggest that uremic serum possibly inhibits thymidine incorporation of normal lymphocytes by imposing an abnormal cyclic GMP/cyclic AMP intracellular ratio, and that levamisole may restore this ratio to normal.

Adolescent↗
PubMed1984

Screening for ochratoxin A in blood by flow injection analysis.

A micromethod for ochratoxin A detection in human sera by flow injection technique is described. The method requires 50 microliter of sera, and it is designed to distinguish samples containing less than 10 ng ochratoxin A per ml. The method is based on fluorescence measurement following a simple extraction procedure for which very small amounts of chemicals are needed. Since the method is not confirmatory, all samples showing fluorescence above a certain intensity have to be reanalysed with some other method where a confirmation step in included. Because of the small amount of serum needed and the rapid procedure (less than 15 min), a large number of samples can be analysed very quickly. The method may therefore be applicable for large screening campaigns conducted to determine the presence of ochratoxin A in blood. This conclusion is based on 1675 samples and 147 standards analysed concurrently by the flow injection technique and an earlier published enzymic method. The method is also suitable for monitoring ochratoxin A levels in the blood of experimental animals.

Chromatography, High Pressure Liquid↗
PubMed1984

Conversion of ochratoxin C into ochratoxin A in vivo.

The conversion of ochratoxin C to ochratoxin A was studied in rats after oral and intravenous administration. The concentration of ochratoxin A in the blood as a function of time was the same after oral administration of equivalent amounts of either ochratoxin C or ochratoxin A. The maximum ochratoxin A concentrations were measured 60 min after administration. Given intravenously, ochratoxin C was also converted to ochratoxin A. Maximum concentrations were reached after 90 min. It is concluded that ochratoxin C is readily converted to ochratoxin A after both oral and intravenous administration. There is reason to believe that a comparable toxicity of the two toxins is based upon this conversion and that only interference with the biotransformation mechanisms may cause a difference in their toxicity.

Administration, Oral↗
PubMed1984

[Rationalization and limits of diagnostic and operative measures in invasive cholestasis diagnosis (percutaneous transhepatic cholangiography) in primary medical care].

In a case of jaundice PTC enables the surgeon to detect its mechanical cause without further delay. This method is especially helpful in smaller hospitals without CT or even sonographic equipment. Explorative laparotomy is no longer necessary. An immediate decision can be made whether to perform a palliative or curative procedure or only to install a percutaneous bile drainage.

Biliary Tract Neoplasms↗