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Biomedical subjects

H Patscheke

Publications and source records attributed to H Patscheke.

69 records · Page 4Linked to original sources
PubMed1978

Superoxide-independent platelet response to xanthine oxidase.

Xanthine oxidase (1--5 microgram/ml) from cow's milk induces shape change, aggregation, and the release reaction of human washed platelets. Xanthine oxidase plus xanthine produce superoxide radicals, which reduce nitro blue tetrazolium. Superoxide dismutase, allopurinol, or ommission of xanthine inhibits the reduction of nitro blue tetrazolium but has no influence on the platelet response to xanthine oxidase. In contrast, small amounts of plasma or apyrase from potatoes abolish the effect on platelets, but not the enzyme activity of xanthine oxidase. Comparison of two xanthine oxidase preparations shows that higher specific enzyme activity corresponds to a lesser effect on platelets. The results suggest that platelet and enzyme activities reside in different components of xanthine oxidase preparations.

Apyrase↗
PubMed1978

The effect of amphiphilic phenylalkyl derivatives on platelet energy metabolism. Stimulation of glycolysis through activation of membrane ATPase.

In order to obtain information about the target of membrane-active inhibitors of platelet aggregation two phenylalkanoles and two phenylalkylamines were examined with respect to their influence on membrane ATPase and energy metabolism. The phenylalkanoles, 2-phenylethanol and 3-phenylpropanol, strongly enhanced the liberation in washed platelets of inorganic phosphate (Pi) from endogenous substrate or added ATP. A simultaneous decrease was found in the ATP/ADP ratio while glucose uptake, glycogen utilization and lactate formation increased. The effects of 2-phenylethanol and 3-phenylpropanol on Pi liberation and ATP/ADP ratio were detectable only with starving platelets; the stimulation of glycolysis could also be seen when glucose was added. It is concluded that presence of glucose enabled the platelets to reincorporate additionally liberated Pi into their ATP pool by virtue of the higher metabolic rate. The data suggest that a membrane-ATPase, possibly thrombosthenin ATPase, is the target of the phenylalkanoles. The phenylalkylamines, 2-phenylethylamine and 4-phenylbutylamine, appeared to inhibit Pi liberation and energy metabolism. Hence the aggregation inhibition produced by amphiphilic phenylalkylamines and phenylalkanoles is not due to a uniform metabolic effect of both classes of derivatives.

Adenosine Diphosphate↗
PubMed1977

Immune complex-induced platelet aggregation and 3H-serotonin release: microtechnique for an assay of virus and mycoplasma antigens or antibodies.

Human platelets are very sensitive indicators of immune complexes. The microplate test presented employs aggregation and/or release reaction of platelets as parameters of an antibody and antigen assay. The measurement of the release reaction is approximately 5 times more sensitive than the examination of aggregation patterns. Antibody titres of patients' sera attained values of 1/780,000 for adenoviruses and Mycoplasma pneumoniae. The determinations of 3H-serotonin release quantitative and therefore allow the equivalence point of a specific antibody/antigen interaction to be shown. This also provides the basis for reliable titre determinations in patients' sera with non-specific, direct platelet reactivity. If such an antiserum is titrated against the corresponding antigen, the release measurements reveal dose-response relations which are characteristic for an effect medicated by immune complexes.

Adenoviridae↗
PubMed1976

Antibody assay for adenoviruses and mycoplasma pneumoniae by the platelet aggregation test.

The practicability of the platelet aggregation test (PAT) in routine antibody assays for adenoviruses and Mycoplasma pneumoniae is demonstrated. An increase in reliability and sensitivity was achieved by employment of EDTA for washing the platelet and by addition of albumin to the test medium. Various lots of platelets yielded reproducible PAT titres which attained 1 : 156,250 in positive patient's sera. Commercially available antigens assigned for complement-fixation (CF) tests proved to be appropriate for the PAT. Checkerboard titrations revealed that the platelet reactivity of immune complexes formed was maintained in a range of up to 625-fold alterations of the antibody: antigen ratio. The fact that PAT and CF titres did not always correlate is interpreted as being due to the differences between complement-fixing and platelet reactivities of various immunoglobulin classes.

Adenoviridae↗
PubMed1975

Concanavalin A-induced aggregation of human blood platelets: Ca++-dependent and Ca++-independent effects.

Concanavalin A (CON A) causes platelets to aggregate. A Ca++-independent effect of CON A could be separated from a main effect which depends on Ca++. The main effect probably is a consequence of the CON A-induced platelet release reaction and therefore is platelet-specific. The weak residual effect observed in the presence of Na-2EDTA may be due to a similar mechanism as has been demonstrated for CON A-induced aggregations of several other normal and malignant transformed animal cells. Na-2EDTA did not inhibit the carbohydrate-specific binding capacity of CON A. Therefore, Na-2EDTA appears not to demineralize the CON A molecules under these experimental conditions. Alpha-methyl-D-glucoside inhibits the Ca++-independent as well as the Ca++-dependent effect of CON A. Pretreatment by neuraminidase stimulated the platelet aggregation induced by CON A. It is possible that removal of terminal sialic acid residues makes additional receptors accessible for the binding of CON A.

Binding Sites↗
PubMed1975

2-phenylethanol and some of its amphiphilic derivatives as inhibitors of platelet aggregation. Structure-activity relationship.

The relationship between chemical structure and inhibitory activity of some simple water soluble phenylalkyl derivatives has been investigated. The inhibitory effect of the following analogous and homologous derivatives increases in the sequence: phenylacetic acid less than 2-phenylethanol less than 2-phenylethylamine = 4-phenylbutyric acid less than 3-phenylpropanol less than 4-phenylbutylamine, i.e., the inhibitory effect is potentiated. 1. by elongation of the alkyl chain, which is accompanied by an increase of the lipophilic character, and 2. when the polar portion is represented by the positively charged amino-group. The effect of these amphiphilic compounds on platelet aggregation appears to be mediated through polar and apolar interactions with the outer layers of the plasma membrane. The fact that the amino derivatives are the most active inhibitors suggests that negatively charged groups may be involved in the polar binding of these inhibitors. Experiments with neuraminidase-treated platelets revealed that the enzymatically removable sialic acid residues are not those negatively charged binding sites. Phentolamine and propranolol which block adrenergic alpha- and beta-receptors, respectively, do not influence the inhibitory effect of these agents.

Adenosine Diphosphate↗