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Biomedical subjects

F Michel

Publications and source records attributed to F Michel.

At least 271 records · Page 15Linked to original sources
PubMed1979

Genetic and physical characterization of a segment of yeast mitochondrial DNA involved in the control of genetic recombination.

Genetic recombination between the 3 RIB (ribosomal) loci of yeast mitochondrial DNA is under the control of a mitochondrial locus named omega (with alleles omega+ and omega-) which is tightly linked to the RIBI locus. We have attempted to elucidate the molecular mechanisms(s) involved by using rho- mutants with similar (RIBI+ RIB2+ RIB3(0) genotype but different recombination properties in rho- x rho+ crosses. These were obtained through pedigree analysis and their mitochondrial DNAs were mapped on a high resolution physical map of the RIB section that had been built by analysis of thermal denaturation profiles and electron microscopy of partially denatured molecules. By comparison of physical and genetic data it can be shown that possession of the omega+ allele by the rho- cell is not sufficient for its expression in crosses, some additional DNA segments(s) in the ribosomal region being needed. This result and several features of the rho+ x rho- crosses are discussed in the light of current concepts in mitochondrial genetics of yeast and the recently discovered fact that omega+ and omega- strains differ by the presence of a 1000 base pairs insertion in the former.

Base Sequence↗
PubMed1979

[Diagnostic and therapy-assessing studies of gingival capillary function by photoplethysmography (preliminary report)].

In the sense of relation pathology, the local peripheral blood supply plays a decisive role also in periodontal diseases. Thus, the differentiation of local circulatory disturbances is of great importance in diagnosis and early detection as well as in therapeutical decisions. Photoplethysmography is well suited for this purpose, especially in evaluating the curves by determining the time of inclination and the plateau index (if necessary, with resort to the nitrangin test). The indicated method also permits to assess the success of therapeutical measures.

Capillaries↗
PubMed1979

[Three case histories of cortical and sub-cortical auditory lesions. Audiological and tomodensimetrical confrontations (author's transl)].

The authors describe three case histories of auditory lesions involving the cortex or subcortex of the temporal lobes. In two of the cases there are minor lesions of the hemisphere producing an amusia without verbal deafness or agnosia of non-verbal sounds. In one of the two patients, the total transitory deafness makes the use of the term cortical deafness debatable. In the third case, a bilateral vascular lesion of the temporal lobes had produced a pure verbal deafness without loss of tone discrimination or loss of the capacity to recognise changes in rhythm or sound frequency. In these three patients in whom there was no anatomical verification, the data given by the scanner and the study of evoked cortical potentials recorded over the two cerebral hemispheres allowed a fairly good study of the correlations between the topography of the lesions and their semiotic consequences.

Audiometry↗
PubMed1979

[Shulman's syndrome: eosinophilic fasciitis (author's transl)].

A detailed report is made of the clinical, histological, biological manifestations of eosinophilic fasciitis, i. e. the Shulman's syndrome, about a 53-year-old man. An extreme induration of sub-cutaneous tissues from arms, legs and trunk, without involvement of the face and extremities, was associated with severe thickening of deep peri-muscular fascias. Raynaud's phenomenon was absent, as were morpheas and visceral involvement. Results of biopsies studied by standard, electron and I. F. microscopy, revealed sclerosis and cellular infiltrates (lymphocytes, plasma cells, histiocytes and eosinophils) in fascia and muscular septa; no changes were seen in epidermis, dermis or sub-cutaneous fat tissue. An elevated ESR, eosinophilia and hyperimmunoglobulinaemia with high levels of circulating immune complexes were the only biological abnormalities. A good response to systemic corticosteroid therapy was observed. These features were similar to those seen in other cases of eosinophilic fasciitis. The etiology and pathogenesis of the Shulman's syndrome remain unclear. A critical review of the literature suggests that eosinophilic fasciitis should be separated from scleroderma and pseudoscleroderma, although this opinion has been discussed.

Adrenal Cortex Hormones↗
PubMed1978

[Ulcers of the neck in hiatal hernias. Perforation into the free peritoneum (author's transl)].

Perforation into the free peritoneum of ulcers of the neck of hiatal hernias is a rare complication. On the basis of one case, which would appear to be the third reported in the literature but the only one in which the special circumstances resulted in the diagnosis being made preoperatively, the authors propose a new therapeutic attitude based upon the physiopathology of ulcers of the neck, combining suturing and reduction of the hernia with anterior repositioning of the greater curvature of the stomach, mobilised according to Thal's technique, and thereby simultaneously producing an anterior hemi-valve.

Aged↗
PubMed1978

Structural requirements for maximal inhibitory allosteric effect of estrogens and estrogen analogues on glutamate dehydrogenase.

The inhibition of glutamate dehydrogenase by estrogens, estrogen analogues or polyphenylethylene derivatives (about one hundred molecules, most of them having estrogenic or antiestrogenic activities) was measured. The efficiency of these compounds in inducing allosteric inhibition of the enzyme was compared and correlated to their chemical structure: an aromatic ring A, a free phenolic group in the region of carbon 3 of the steroid nucleus and a lipophilic substitution in the region of C-12, C-13 or C-17 were found to be the main structural features required for maximal efficiency on glutamate dehydrogenase. A tentative model for the relative orientation of the main inhibitor families is proposed. It accounts for most of the kinetic results and can be used as a tool for the selection of affinity labels directed towards the estrogen binding site of glutamate dehydrogenase.

Allosteric Site↗
PubMed1978

Affinity labelling of the estrogen binding site of glutamate dehydrogenase with iodoacetyldiethylstilbestrol. Selective alkylation of cysteine-89.

Iodoacetyldiethylstilbestrol was used as an affinity label to alkylate the estrogen binding site of bovine liver glutamate dehydrogenase. This reagent induced inactivation and alkylation of the enzyme. The non-alkylating analogues diethylstilbestrol and estradiol protected the enzyme towards alkylation. The apparent constant of alkylation was of the order of magnitude of I50 for the allosteric inhibition by diethylstilbestrol. These two results suggest that alkylation occurred at the estrogen binding site. The stoichiometry of alkylation was between one and two, depending on the experimental conditions. When the stoichiometry was found to be less than or equal to 1, 90% of the label was bound on cystein residues, 70% of which was carried by cysteine-89, a cysteine residue which is known to be inacessible to iodoacetamide in phosphate buffer in the same conditions of temperature and pH.

Affinity Labels↗
PubMed1978

[Pancreatic transplantation. Implantation of auto and allografts of the pancreas into the gastric wall of the diabetic rabbit (author's transl)].

The author's studied pancreatic autotransplants and allotransplants in the gastric submucosa of the rabbit after removal of the pancreas. Pancreatctomy causes severe diabetes with hyperkaliemic acidosis which is always fatal with 72 hours. Auto or allotransplantation cures the diabetes within two to three days, and maintains normal glucose balance for about 60 days. Early death after transplantation occurred when the graft was totally ineffective. After transplantation, the blood sugar rose progressively towards the 15th day, then suddenly and definetely at the time of necrosis of the graft towards the 15th or 21st day. The follow up in some transplanted animals exceeded two months. The interest of the procedure resides in the implantation of a large critical mass (25 to 30% of the pancreas ) in a well-vascularised area, drained by the portal system, and permitting the digestive tract elimination of the pancreatic necrosis whether of vascular or immune origin.

Animals↗
PubMed1978

[Anaerobic bacteria in digestive surgery. Pathogenic role and prognostic incidence (author's transl)].

The authors isolated in common surgical practice 83 anaerobic bacteria mainly bacteroides and clostridia. They analyse their pathogenic role in relation to the site of sampling. Comparing the bacteriological results with a clinical study of 96 cases of generalised peritonitis, there appeared to be no significant differente between the prognosis in peritonitis and anaerobic bacteria and those without anaerobic bacteria. The mortality was identical in septicemia due to anaerobic and aerobic bacteria; jaundice was just as frequent in both series. However, the prognosis of peritonitis due to anaerobic bacteria seems better when antibiotic treatment is adapted to the bacteria, e.g. lincomycin, metronidazole. With regard to anaerobic bacteria, which represent only part of the fecal flora, it may be dangerous by selection of resistant strains to use prophylactic antibiotics as a routine; local treatment of the septic focus seems the most important. The pathogenic role of anaerobic bacteria in digestive pathology is far from clearly defined; one should not follow the fashion of using even specific antibiotics without justification.

Adolescent↗
PubMed1977

[Hemispheric asymmetries of the human brain].

The authors studied 181 brains, 103 of which were dissected. They observed a "T1-T2 bridge" over the first temporal and second temporal gyri more often on the left side than on the right. This asymmetry was more frequent in males than in females. The maximal width of the superior aspect of the second temporal gyrus was greater on the right side in the majority of cases. By contrast, the fusiform gyrus was found wider on the left side in most subjects. The length of the precuneus was greater on the right. The greater size of the left planum temporale could be correlated with the sectional area of the anterior white commissure. The same correlation was found between the length of the precuneus and the area of the latter commissure. Anatomical asymmetries of the two cerebral hemispheres in man seem to be numerous. The interpretation of these asymmetries is difficult; some are likely to be related to functional asymmetries. In the future, the study of morphological asymmetries in routine neuropathology, in patients who have been submitted to detailed neuropsychological examination, would appear to be desirable.

Cerebral Cortex↗
PubMed1976

Recombined molecules of mitochondrial DNA obtained from crosses between cytoplasmic petite mutants of Saccharomyces cerevisiae: the stoichiometry of parental DNA repeats within the recombined molecule.

We have studied recombination between repetitive mitochondrial DNAs from cytoplasmic petite mutants of Saccharomyces cerevisiae. Mitochondrial DNA was isolated from two parental p- mutants, carrying respectively the CR and the ER mitochondrial genetic markers, and from two p- CRER diploid genetic recombinants. These two recombinants, obtained from the same parental petites, differ in their degrees of suppressiveness. The p- mitochondrial DNAs were analyzed by DNA-DNA hybridization, high resolution melting and reassociation kinetics. It was found that the repeating unit of the CR parental p- DNA is 3 to 4 times longer than that of the ER parent. There is very little sequence homology between these two p- mitochondrial DNAs and almost all parental sequences are integrated into the recombined molecules. Mitochondrial DNA from both types of recombinants seems to contain the two parental repeating units in the ratio 1:1.

Base Sequence↗