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Biomedical subjects

J Hofmann

Publications and source records attributed to J Hofmann.

At least 163 records · Page 9Linked to original sources
PubMed1981

Effect of arachidonic acid on the hexose monophosphate shunt and related coenzymes in human blood platelets.

The aggregation of human platelets after addition of arachidonic acid (AA) is accompanied by a 30 fold increase in the net flux through the hexose monophosphate shunt (HMPS). The levels of reduced glutathione (GSH) and NADPH as well as the NADPH/NADPH+NADP quotient show a temporary fall which is restricted to the interval between AA addition and beginning of aggregation suggesting a lag phase between the onset of enhanced coenzyme consumption and that of increased coenzyme regeneration. together with literature data the results point to a possible regulatory function of reduced coenzymes and the HMPS in the process of platelet activation.

Arachidonic Acid↗
PubMed1981

Suppressive and causal prophylactic activity of floxacrine in various avian malaria models.

Floxacrine, a 7-chloro-10-hydroxy-3(4-trifluoromethylphenyl)-3, 4-dihydroacridine-1,9-(2H, 10H)-dione and various standard malarials were found to be distinctly less active against avian malaria parasites than against rodent or nonhuman primate malaria parasites. Especially the suppressive action against asexual stages of P. gallinaceum, P. praecox and P. cathemerium was markedly reduced in comparison with that ascertained in mice infected with P. berghei. Similar results were observed in sporozoite-induced infections of P. gallinaceum and P. cathemerium respectively. Expressed as quotient of calculated causal prophylactic activity (CPD50) floxacrine was 42 and pyrimethamine 54 times more active against P. berghei yoelii than P. gallinaceum. The blood schizontocidal effect of floxacrine proved superior to that of mefloquine, chloroquine and mepacrine, whereas the causal prophylactic activity was slightly inferior to that of pyrimethamine but superior to that of primaquine. In vitro floxacrine revealed no effect against sporozoites of P. gallinaceum even at concentrations of 100 mcg/ml.

Acridines↗
PubMed1981

Glucose-6-phosphate dehydrogenase deficiency in human platelets and its effect on platelet aggregation.

Platelets from patients with known red blood cell G-6-PD deficiency were investigated to find out whether this genetic defect is associated with changes in platelet aggregation. The enzyme defect in platelets could be verified by a decreased G-6-PD activity which was as low as 15% compared to control subjects. The decreased enzyme activity was reflected by lowered levels of NADPH and GSH and by a diminished maximum capacity of the hexose monophosphate shunt. Aggregation measurements in platelet-rich plasma from deficient patients revealed an enhanced dose response to ADP which was higher by about one order of magnitude compared to controls. The same effect was observed in a smaller degree in arachidonic acid induced aggregation.

Blood Platelets↗
PubMed1980

Anticoagulant-free prepared blood platelets and the effect of calcium on their aggregation behaviour.

Human blood platelets were prepared by gel filtration of native blood and subsequent centrifugation in a Ficoll density gradient avoiding any anticoagulant during the preparation. In ADP, ionophore A 23 187 and thrombin induced aggregation an increase in extracellular Ca++ enhanced the velocity of aggregation. From a defined Ca++ concentration threshold on there was a shift from monophasic to biphasic aggregation.

Adenosine Diphosphate↗
PubMed1979

Islet transplantation in experimental diabetes of the rat. VI. Rate of regression in diabetic kidney lesions after isogeneic islet transplantation: quantitative measurements.

Intraportal transplantation of isogeneic adult islets in diabetic rats resulted in long-lasting amelioration of the metabolic disorder. The effect upon diabetes-induced kidney changes (enlargement of mesangial space, capillary changes, cell-proliferation) was examined quantitatively by morphometric studies. The major effect was a remarkable reduction of the mesangial space and re-widening of the capillary lumina. The number of endothelial cells was lowered. Regarding epithelial and mesangila cells no difference was observed between normal, diabetic and transplanted animals of age-matched groups.

Animals↗
PubMed1979

The use of acridine orange for testing blood platelet integrity.

Two processes are involved in the accumulation of acridine orange in human blood platelets. One follows a diffusion like kinetics and is independent of the ATP level whereas the second one can be completely abolished by ATP depletion. The acridine orange incorporation rate seems to be a suitable parameter for testing platelet integrity. It reflects very sensitively the influence of the preparation method as well as of anticoagulating substances used on the stability of platelet suspensions. The rates of acridine orange incorporation and of aggregation were measured in platelet-rich plasma and in saline suspended platelets after gel filtration, respectively, over a period of 120 min storage. Both rates are influenced to a different degree by anticoagulating agents such as citrate, heparin and EDTA. When contact with anticoagulating agents during platelet preparation is avoided, platelets show a constant acridine orange incorporation and aggregation during storage and the smallest morphological alteration.

Acridine Orange↗
PubMed1979

[Preparation of human platelets without the use of anticoagulants and study of the effect of Catt on aggregation].

A method for the preparation of human blood platelets is presented which substitutes the use of anticoagulants by a gelfiltration for the removal of plasma calcium from native blood. In a second step the platelets are separated from the gel filtered blood by a centrifugation on a Ficoll density gradient. The anticoagulant-free platelets reveal an intact morphological feature and a normal aggregation behaviour in response to different aggregation inducers. It was found that in ADP-induced aggregation monophasic aggregation is shifted to a biphasic one by increasing concentrations of extracellular calcium.

Blood Platelets↗
PubMed1976

Tension pneumothorax: a teaching model.

A TPT induced in a small rabbit is an excellent teaching model for the treatment of a TPT in the small human neonate. Pediatric housestaff, neonatal nurses, and others have utilized this model to gain confidence and expertise in the diagnosis and treatment of TPT. The rabbit model is inexpensive, readily available, and recreates the clinical condition of a TPT in an educational environment.

Animals↗