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M Dumitrescu

Publications and source records attributed to M Dumitrescu.

At least 19 recordsLinked to original sources
PubMed1996

Spectral and interferometrical study of the interaction of haemin with glutathione.

The interaction of haemin with reduced glutathione (GSH) was investigated in vitro and the association constant was determined by both spectrophotometric and interferometric methods. In order to elucidate the nature of this interaction, the reaction of haemin with a typical reductive agent (sodium dithionite) and a typical chelating agent for hem-iron (histidine) was also studied. Haemin-induced haemolysis in the presence and absence of GSH was monitored spectrophotometrically. The results outline the role of GSH at physiological concentration in preventing erythrocyte damage by haemin.

Erythrocyte Membrane↗
PubMed1995

Correlation between membrane potential changes and proliferation of murine peritoneal lymphocytes stimulated by Nocardia water soluble mitogen.

A comparative study of Nocardia water soluble mitogen (NWSM) action on membrane potential and proliferation rate of murine peritoneal lymphocytes was performed at various incubation times. The membrane surface charge was evaluated by laser doppler velocimetry (LDV) through the measurement of the cell electrophoretic mobility at different pH values (from pH 5 to 9). We demonstrated that NWSM treatment decreases the lymphocyte membrane potential. This variation reached a maximal level after 24 hrs. at pH 7 and remained unchanged during the 72 hrs. observation. A significant stimulation of lymphocyte proliferation was noted after a 24 hrs. incubation. However, the highest rate of [3H]-thymidine incorporation was observed at 48 hrs. with a subsequent decrease at 72 hrs. On the basis of these data, it is suggested, that membrane potential changes may represent an early important step in the mechanism of lymphocyte activation by NWSM, as it has been shown for some mitogenic compounds.

Animals↗
PubMedDate not supplied

Spectrophotometric assay of the interaction of Plasmodium berghei infected erythrocyte lysates and neutral red.

In order to reveal by absorption spectrophotometry the redox differences between the Plasmodium berghei infected erythrocyte lysates (MEL) and the healthy ones (HEL) we studied their interaction with the neutral red (NR) redox dye. The variation of the dye absorption intensity at 540 nm as a function of the hemoglobin content of the samples was attributed to the redox potential variation of the different hemoglobin aggregates formed in the samples containing different hemoglobin quantities. By short term treatment of the lysates with ascorbic acid in the presence of NR, great redox reactivity difference was proved between MEL and HEL as revealed by absorption and explained by the initial higher oxidation state of the Hb iron in MEL than in HEL.

Animals↗
PubMedDate not supplied

[The mechanisms of the antiherpetic action of aqueous propolis extracts. I. The antioxidant action on human fibroblast cultures].

A redox state modulation model was worked out in human fibroblast cultures treated with oxidation stress inducing agents and a redox agent, virtually protecting cell against the stress. Quantification of the global redox changes in fibroblasts was done using the hemoglobin electronic spectrum, in the presence and in the absence of H2O2.

Antioxidants↗
PubMedDate not supplied

[Evaluation of the etiopathogenic significance of E. coli serotypes 0 1--0 25].

A study was carried out on the incidence of E. coli serogroups 01--025, under different clinical and epidemiologic conditions, with a view to evaluating their etiopathogenic significance and the efficiency of immunofluoresence as a rapid laboratory method of diagnosis. A total number of 1542 samples were collected from humans (1075 feces samples and 467 urine samples from cases of urinary infection), and 387 from animals. The samples were collected from cases of enteritis and from healthy children and adults: 285 samples from infantile enteritis cases; 200 samples from adults with enteritis; 31 samples from healthy children: and 559 samples from healthy adults. These E. coli serogroups were found in humans, in both pathologic and normal conditions. The proportion of isolations of E. coli serogroups 01--025 was greater in the feces samples from healthy subjects than in the samples from enternal or urinary infections (48.80% as against 23.21%), demonstrating the opportunist character of these germs. Positive results were obtained in 30.23% of the products of animal origin (monkeys, dogs, chickens), pointing to the wide spread of these serogroups in nature. Serogroups 04 and 025 were predominant in both the human and animal products. The rapid immunofluorescence diagnosis cannot be applied to these serogroups owing to the multiple and varied antigenic fractions. The laboratory diagnosis can only be established in pure cultures by identification of the groups, by biochemical and serolgic methods, by agglutination reactions on slides and in test tubes.

Adolescent↗