Biomedical subjects

R Marx

Publications and source records attributed to R Marx.

25 records · Page 2Linked to original sources

PubMed1976

[Modification of glycylglycine dipeptidase activity in the human ovary using follicle stimulating hormone. I].

The glycyl glycine dipeptidase activity under the in vitro influence of two follicle-stimulating hormone preparations of different concentration was investigated in 36 ovaries. A significant impediment was observed under Folistiman, whereas under Anthrogon the impediment could only be detected with higher concentrations. The FSH/ICSH relation evidently plays an important role in this respect. The results are in support of the statement that the glycyl glycine activity in vivo also depends on the gonadotrophin production. At the same time they affirm the fact that not only endopeptidases play a role in the hormone metabolism of the ovary.

Adnexa Uteri↗

PubMed1975

Comparative investigation on the influence of human and bovine collagen types I, II and III on the aggregation of human platelets.

Collagen types I, II and III from man and calf are distinctly different with respect to their effect on the induction of the aggregation of human platelets. Collagen type III was found to be a particularly potent inducer of platelet aggregation. The pathogenetic implications of these observations are briefly discussed.

Amino Acid Sequence↗

PubMed1975

[Hemostaseopathies in chronic, azotemic renal insufficiency. Pathogenesis, diagnosis, treatment (author's transl)].

A brief survey on the current concepts of diagnosis and pathogenesis of platelet dysfunction in chronic renal insufficiency is given on the basis of clinical hemostaseological investigations. Phenolic compounds, guanidine succinate and fibrin decomposition products are prominent in the discussion of uremia toxins possibly involved in disorders of thrombocytic function. Clinically practicable methods of analysis are briefly presented and the still imperfect status of therapy is emphasized.

Blood Coagulation Disorders↗

PubMed1975

[Stimulating effect of collagen and collagen derivatives on the propregation and adhesion of thrombocytes in defibrinogenated human citrate plasma and in animal citrate plasma].

Collagen type I form calf skin, collagen modified by pepsin, methylation, succinylation or deamidation and alpha1-chains or cyanogen bromide peptides were studied for their effect on adhesion and spreading of platelets. Some of the proteins increased platelet activity and indicated that the following structural parameters are of importance: 1. triple-helical conformation, 2. non-triple-helical regions, 3. charged amino acid side chains, 4. some activity was also detected for cyanogen bromide peptides of collagen alpha1-chain. The activity of collagen when used in a firbrinogen-free system is comparable to that of fibrinogen and potentiates platelet spreading caused by animal plasma.

Afibrinogenemia↗

PubMedDate not supplied

Crack, sex, and STD.

Increasing rates of syphilis, gonorrhea, chancroid, and sexually transmitted human immunodeficiency virus infection appear to be related to crack cocaine use. This article critically reviews 16 epidemiologic studies that examine drug use, sexual behavior, and sexually transmitted disease (STD). Eight studies found an association between crack and STD, one study found no association between crack and STD, and seven studies found STD to be related to other drugs or methods of cocaine use. The exchange of sex for money or drugs was associated with STD in seven studies. Publications that were reviewed have numerous methodologic weaknesses: broader sampling, uninfected comparison groups, and greater specification of drug use and sexual risk behaviors are needed. Further research should compare different drugs and associated sexual behavior and STD to assess the unique risk conferred by crack. Designing effective interventions will require investigation of risk behavior determinants and barriers to health care.

Chancroid↗

PubMedDate not supplied

The quaternary structure of yeast aminopeptidase I. 1. Molecular forms and subunit size.

The smallest active form of aminopeptidase I (EC 3.4.11.1) from yeast has a molecular weight of 6.4 X 10(5). At neutral pH the active enzyme is in equilibrium with two inactive subfragments (Mr = 3.2 X 10(5) and 1.1 X 10(5)) as well as with higher aggregates (Mr greater than or equal 1.2 X 10(6)). All of these species may be dissociated to give a single type of subunits with a molecular weight of 5.3 X 10(4). It is concluded that the active enzyme is a dodecamer whereas the subfragments correspond to dimeric and hexameric forms.

Aminopeptidases↗

PubMedDate not supplied

The quaternary structure of yeast aminopeptidase I. 2. Geometric arrangement of subunits.

Electron micrographs of native aminopeptidase I and of isolated subfragments were taken after negative staining with uranyl formate. From these studies and from the chemical evidence summarized in the preceding paper it is concluded that the active enzyme is a dodecamer possessing pseudo-D3 symmetry with the dimer as the smallest symmetric unit.

Aminopeptidases↗