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Biomedical subjects

M M Klein

Publications and source records attributed to M M Klein.

16 recordsLinked to original sources
PubMed1990

L-arginine and arginine analogues: effects on isolated blood vessels and cultured endothelial cells.

1. The present study examined effects of arginine (Arg) and various Arg analogues on the vascular tone of rabbit and rat aortic rings, the release of nitrite from cultured bovine aortic endothelial cells and the metabolism of L-Arg in bovine and porcine endothelial cell homogenates. The respective D-enantiomers or N-alpha-benzoyl-L-arginine ethyl ester did not substitute for L-Arg. 2. In bovine aortic endothelial cells, the release of nitrite was only observed in the presence of L-Arg or L-Arg methyl ester in the cell culture medium. 3. In dialyzed homogenates of porcine and bovine aortic endothelial cells, L-Arg was metabolized independently of NADPH and Ca2+ to yield L-ornithine (L-Orn) and L-citrulline (L-Cit). No concomitant nitrite formation was detected. 4. Pretreatment of rabbit and rat aortic rings with L-canavanine (L-Can) or NG-monomethyl-L-Arg (L-NMMA) inhibited ATP- and acetylcholine-induced relaxations (endothelium-dependent) but not glyceryltrinitrate-induced relaxations (endothelium-independent). 5. In rabbit aortic rings, Arg and monomeric Arg analogues induced endothelium-independent relaxations. L-Arg methyl ester induced an endothelium-independent contraction, and L-NMMA induced a relaxation in the absence of endothelium and a contraction in the presence of endothelium. Polymeric basic amino acids such as poly L-Arg induced endothelium-dependent relaxations (inhibited by L-Can), a subsequent refractoriness to endothelium-dependent vasodilators (not prevented by L-Can) and endothelial cell death. 6. We suggest that extracellular L-Arg is essential for the formation of endothelium-derived nitrogen oxides (EDNO). However, Arg and Arg analogues do not exert endothelium-dependent relaxation. L-Can and L-NMMA inhibit endothelium-dependent relaxation, consistent with an inhibition of EDNO formation from L-Arg, but also exert endothelium-independent effects on vascular tone.

Animals↗
PubMed1988

Arginine is a physiological precursor of endothelium-derived nitric oxide.

ATP dose dependently stimulated the formation and release of nitric oxide (NO) from perfused rabbit aorta. L-Canavanine, an inhibitor of various L-arginine-utilizing enzymes, abolished basal and ATP-induced NO formation and release. ATP increased the accumulation of presumably NO-derived NO2- in the medium of primary cultures of bovine aortic endothelial cells. 15NO, 15NO2- and 15NO3- formation was found when L-[guanido-15N2]arginine was added to the culture medium. We conclude that the terminal guanidino nitrogens of L-arginine are the physiological precursors of endothelium-derived NO.

Animals↗
PubMed1983

Psychological differentiation, self-concept, and object relations of adolescents as a function of family consensual types.

Thirty-three intact families consisting of an adolescent referred for psychotherapy, and a sibling adolescent, were classified according to the Reiss Card Sorting Test. All the families fit two of the types described by the theory of Reiss, the consensus sensitive and the distance sensitive; none were from the environment sensitive. Significant differences were found to exist between the adolescents in these two family types on personality measures. The adolescents from consensus-sensitive families showed a higher level of psychological differentiation, a higher self-concept, and more mature object relations than adolescents from the distance-sensitive families. The results verify and broaden aspects of Reiss' theory and are discussed in consideration with the development that has taken place in family therapy and research. They suggest that the relationship between the family and the adjustment of its children can be better understood and predicted on the basis of the family type.

Adolescent↗
PubMed1972

Nucleic acid enzyme studies of nonfermentative gram-negative bacteria using thin-layer chromatography.

A rapid and easy to perform procedure for determining the nucleic acid enzyme reactions of intact bacterial cells was developed. Overnight organism growth on triple sugar agar was tested for nucleoside phosphotransferase, nucleosidase, and nucleotidase activity. Reaction products were detected by means of thin-layer chromatography and fluorescence. Characteristic patterns were seen with certain strains of nonfermentative gram-negative bacteria, which indicated that these tests could aid in classification and identification of E0-1 group, Pseudomonas multivorans, P. cepacia, P. maltophilia, certain other Pseudomonas species, and Herellea vaginicola.

Acinetobacter↗