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Biomedical subjects

H Weicker

Publications and source records attributed to H Weicker.

At least 91 records · Page 5Linked to original sources
PubMed1979

Amino acid transport in the exocrine pancreas. IV. Do glucagon or insulin mediate the in vivo effect of caerulein on amino acid transport and incorporation?

The direct in vitro effect of caerulein on pancreatic protein synthesis and amino acid transport has been investigated. In contrast to in vivo conditions we were unable to demonstrate any effect on alpha-aminoisobutyric acid and leucine uptake and on leucine incorporation usin rat pancreatic lobules. Insulin and glucagon were therefore examined as possible mediators for the in vivo effect of caerulein. Insulin (1--5 microM) slightly enhanced AIB uptake (16% but did not change uptake and incorporation of leucine. Glucagon (0.01--1 microM) was ineffective. Both islet hormones had no influence on the formation of cyclic GMP induced by secretagogue either in rat (40% increase) or in guinea pig lobules (500% increase). It seems unlikely that the two islet hormones exert any direct effect on the exocrine pancreas and thus could serve as mediators for the in vivo synthetic effect of caerulein.

Aminoisobutyric Acids↗
PubMed1978

Cardiopulmonary adjustment and metabolic response to maximal and submaximal physical exercise of boys and girls at different stages of maturity.

Cardiopulmonary and metabolic variables were investigated at maximal and submaximal bicycle ergometer exercises in 41 swimmers of both sexes, 8--18 years old. VO2 max and VO2 max . HR-1 were higher in boys than in girls and increased with maturity, while VO2 max. kg-1 and HVE were not influenced by this. The HV increased clearly during this growth period, the pubertal and postpubertal subjects showing 16 and 17% higher values for HV and HV . kg-1 than those reported in normal schoolchildren populations. During the submaximal exercise at 70% VO2 max the highest HR values were found in the prepubertal group, whilst the lowest were observed in the postpubertal subjects. These findings suggest that a given percentage of VO2 max as a reference unit, is more reliable than a certain HR to obtain comparable results in subjects with different ages. Blood samples were collected before, during, and after the submaximal exercise. Blood glucose and FFA did not differ in relation to the stages of maturity. During exercise, insulin decreased in prepubertal children, did not alter in pubertal adolescents, and increased in postpubertal subjects. The lactate concentration, during exercise, increased in relation to maturity. The same results were found for HGH, but no differences were found with regard to sex. Since the pattern of HGH secretion during exercise is similar to that found after arginine and insulin administration it is assumed that the same mechanism (i.e., sex hormones) triggers the HGH release.

Adolescent↗
PubMed1977

Membrane phospholipid composition and anaphylactical response of cardiac and smooth muscle fibers in the Rh (D) system.

The anaphylactical response of sensitized smooth and cardiac papillary muscle fibers as target organs was induced by the stimulation of the complement systems in the antigen-antibody reaction of albumin and anti-albumin. However in the Rh (D) system anaphylaxis was only elicited on smooth muscle segments with the corresponding antigen. This discrepancy between both immune systems cannot be explained only by the fact the Rh (D) anti-D reaction does not stimulate the complement activity. Since this antigen-antibody reaction requires a protein phospholipid interaction, the failure of anaphylactical response on cardiac muscle fibers may be due to its phospholipid environment which differed considerably from that of the smooth muscle fibers. Besides the differences in composition and amount of the phospholipids the fatty acid distribution of phosphatidylethanolamine, phosphatidylcholine, sphingomyelin, cardiolipin derived from cardiac or smooth muscle membranes varied clearly. This may influence the protein phospholipid interaction which is essential for the antigen-antibody reaction of the Rh (D) system.

Anaphylaxis↗
PubMed1977

[Impairment of the cation transport on Rh-pos. human red cells after incubation with IgG-anti-D (author's transl)].

Rh-pos. human red cells sensitized with IgG-Anti-D showed at 4 degrees C an intracellular Na+-accumulation, which was amplified by an increase in the Na+-concentration in the incubation medium. This increase of the intracellular Na+-concentration may be due to a passive Na+-influx since the Na+-K+-ATPase system does not work at this temperature. At the optimal reaction-temperature of the enzyme the Na+-K+-ATPase activity of the sensitized Rh-pos. red cells was inhibited proportionally to the anti-D concentration. Both the amplified Na+-influx and the inhibition of the active Na+-transport caused an osmotic hemolysis. The hemoglobin release was significant above the anti-D titer step of 1:512. This mechanism suggests that the intravasular part of the immunohemolysis with Rh incompatibility was generated by an impaired active and passive cation transport following the antigen-antibody reaction. This suggestion is supported by the fact that IgG-Anti-D neither stimulated the complement system nor the intravascular monocyte mediated cell lysis, since the activity of the effector cells is reduced by the surplus of sensitized red cells and the presence of other inhibiting IgG immunoglobulins. The biochemical relationship of the Rh-D-antigen and the Na+-K+ATPase both located on membrane lipoproteins, may be the reason why only the antigen-antibody reaction in the Rh-D system impaired the cation transport. The antigen-antibody reaction of IgM-Anti-A and of the cold agglutinin IgM-Anti-I reacting with glycolipid and with glycoprotein membrane antigens respectively did not impair the cation transport after complement inactivation.

Adenosine Triphosphatases↗
PubMed1976

Automatic potentiometric titration and gas-liquid chromatography of underivatised free fatty acids.

A rapid and precise method is described for the determination of total free fatty acids (FFA) in the serum followed by the separation of individual FFA by gas-liquid chromatography (GLC). After the extraction the FFA are directly injected into the gas-liquid chromatograph without esterification. DEGS-PS serves as stationary phase. The esterified fatty acids such as cholesterol esters, phospholipids or triglycerides do not interfere with the FFA determined by the GLC method. This method is compared to other commonly used titrimetric and gas-chromatographic procedures. The changes of the composition of individual FFA during and after ergometer work is reported.

Autoanalysis↗
PubMed1975

The I antigen of human red cell membrane.

A high-active I antigen was isolated from human red cells after papainization. Investigations on its chemical composition and its serological properties are reported. 1. The I antigen activity was clearly demonstrated by hemagglutination inhibition studies and by the immuno-double-diffusion with all available anti-I sera. 2. The I antigen did not react with other antibodies directed against red cell antigens thus proving its specificity. Any relationships to antigen activities within the Pr-1/Pr-2, MN, and ABO systems could be excluded. 3. The substance was shown to be a glycoprotein and not a glycolipid. This was confirmed by different delipidation procedures promoting always an increase of I activity. The delipidized material contained only traces of fatty acids, and did not move on thin-layer chromatography in solvent systems normally used for glycolipid development. 4. The I determinant resides on alkali-stable oligosaccharide chains. The main sugars are galactose and N-acetylglucosamine which might be involved in the immunodeterminants.

Amino Acids↗
PubMed1975

[The importance of phosphatidylcholine in the binding of anti-D to human erythrocyte ghost membrane (author's transl)].

Incubation of Rh positive ghosts with phospholipase A2 and C abolished the adsorption of Rh antibodies on the ghosts; incubation with phospholipase D, however, did not affect their adsorption and none of these phospholipases affected the adsorption of antibodies of the ABO system. The impairment of antigen-antibody-reaction in Rh positive ghosts treated with phospholipase corresponds to the absence of the antigen-antibody reaction with the membrane protein associated with Rh characteristics in the Schultz-Dale-Test. The chromatogram of the phospholipids extracted from those stromata treated with various phospholipases and those not treated showed different patterns. After incubation with phospholipase-A2 the lecithin and cephalin streaks were reduced and in addition lysophosphatide and fatty acid streaks were detected. In the case of phospholipase C the lecithin and cephalin streaks were further reduced while diglyceride streaks made their appearance. The phospholipid extracts from those stromata treated with phospholipase D and those not treated were identical. Phospholipase C reduced the values of lipid phosphorus more than did phospholipase A2, while phospholipase D did not reduce them at all. This study supports the results of other investigators who have postulated that the Rh antigens are located in a lipoprotein on the membrane of the human erythrocyte. The antigen-antibody-reaction seems to require a precise protein-phospholipid interaction.

Binding Sites, Antibody↗