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Biomedical subjects

M Denis

Publications and source records attributed to M Denis.

At least 253 records · Page 14Linked to original sources
PubMed1979

A temperature-induced absorption band centered in the region of 666 nm related to the configuration of the active site in frozen cytochrome oxidase.

The existence of a temperature-induced absorption band centred in the region of 666 nm is demonstrated for both membrane-bound and soluble cytochrome oxidase in the frozen state. The 666 nm band is generated solely by an increase in temperature of both fully reduced and mixed valence state cytochrome oxidase in the presence of CO or O2 within the 'pocket' containing the active site; it is not formed in the absence of both CO and O2 from the sample. The formation of the 666 nm band is entirely reversible when the temperature is decreased again and its formation is not dependent on the presence of liganded CO at the sixth coordination site of haem a3 in the low temperature range (below --120 degrees C) prior to photolysis. The shape and intensity of the 666 nm band are not affected by the extent of CO recombination following flash and photolysis and temperature increase and are not affected by changes in the valence states of the four metal centres when the O2 reaction is in progress.

Animals↗
PubMed1976

Test of the incidental-cues hypothesis.

Five groups of adult Ss were submitted to free-recall learning of 24 objects presented as written nouns for the control group and as pictures for experimental groups, as follows: schematic black and white, schematic colored, detailed black and white, and detailed colored drawings. Pictures were better recalled than nouns. Recall was significantly inferior for schematic black and white than for detailed colored drawings, with schematic colored and detailed black and white drawings at an intermediate level. These results support the so-called incidental-cues hypothesis according to which the best recall of pictures in comparison with that of nouns is partially the result of pictures having more distinctive cues likely to be encoded than do verbal items.

Adolescent↗
PubMedDate not supplied

Neutralization activity and persistence of antibodies induced in response to vaccination with a novel mumps strain, RIT 4385.

BACKGROUND: We have previously shown that a new measles, mumps, rubella (MMR) vaccine, Priorix, with a novel mumps component elicits anti-mumps antibody titers comparable to the licensed M-M-R II vaccine. MATERIALS AND METHODS: To ensure that these antibodies had neutralizing activity against wild-type mumps virus, sera were prepared 2 and 18 months after vaccination of 12-24-month-old infants with either Priorix or M-M-R II and ELISA antibody titers and neutralizing activity were determined. RESULTS: After 2 months, Priorix and M-M-R II vaccines elicited comparable ELISA antibody titers and neutralizing activity. At 18 months ELISA seropositivity rates were 80-81% and 94-96% of vaccinees had neutralizing activity. All ELISA seropositives had neutralizing activity. CONCLUSION: These data suggest that both vaccines provided equivalent protection against mumps over this 18-month period.

Antibody Formation↗
PubMedDate not supplied

Evidence for a photoactivation of CO rebinding to fully reduced cytochrome c oxidase after low-temperature flash photolysis.

Carbon monoxide rebinding to isolated fully reduced cytochrome c oxidase has been investigated by low-temperature, flash photolysis, dual-wavelength spectrometry. By using separately different wavelength pairs to monitor the liganding of CO to Fe a3 and by keeping all other experimental conditions identical, there has been singled out a photoactivation effect on CO rebinding. For instance, at 187 K, the rate constant of CO rebinding observed at 425-475 nm was twice that derived from the kinetic at 444-475 nm despite a rate constant of photodissociation about 10 times larger at 425-475 nm than at 444-475 nm. This new finding is discussed with respect to previous investigations under similar conditions.

Animals↗
PubMedDate not supplied

Isolation and characterization of cytochrome b5 from Candida tropicalis grown on alkane.

Cytochrome b5 from Candida tropicalis grown on alkane has been solubulized in three different ways (sodium cholate, trypsin, osmotic wash). After solubilization of the microsomal membrane with sodium cholate, the purification of cytochrome b5 was achieved by DEAE-cellulose chromatography, hydroxylapatite chromatography, a second DEAE-cellulose chromatography and a Sephadex G-75 gel filtration. The purified protein had an apparent molecular weight of 16 000 +/- 1 000. After solubilization by trypsin treatment or osmotic wash, the purification procedure yielded a protein with an apparent molecular weight of 12 000 +/- 1 000. Though the purified proteins presented molecular weights depending on the technique of solubilization, they exhibited identical optical properties, a great stability with respect to temperature and pH, and were all autooxidable. Redox titrations revealed differences in their midpoint potential values, which were 35 +/- 5 mV for the b5 purified after cholate solubilization, -59 +/- 5 mV for the b5 purified after trypsin treatment and -65 +/- 5 mV for the b5 purified after osmotic wash.

Alkanes↗
PubMedDate not supplied

[Isolation and description of strains of Flavobacterium multivorum of telluric origin].

Twenty encapsulated strains of Flavobacterium multivorum were isolated from soil by elective culture in minimal medium containing inulin as the sole source of carbon and energy. These strains were compared with the type strain and with 5 other strains (including 4 clinical strains) of F. multivorum. Of 168 substrates tested, 18 carbohydrates were used as the sole carbon and energy source by all 26 strains. A few amino acids were used by some strains. The yellow pigment produced was found to be a carotene and its production was photo-inducible. The presence of a cytochrome c oxidase of the aa3 type was suggested by absorption spectra. The major cell lipids were phosphatidylethanolamine and sphingolipids; the major fatty acids were 13-methyltetradecanoic and 2-hydroxy-13-methyltetradecanoic acids. Soil and clinical strains of F. multivorum showed roughly similar patterns of antibiotic multiresistance. The average G + C content of the DNA of 11 strains was 40.8 +/- 1.5 mol%.

Anti-Bacterial Agents↗
PubMedDate not supplied

AIDS virus-specific cytotoxic T lymphocytes in lung disorders.

Human immunodeficiency virus (HIV) is implicated in the development of AIDS (acquired immune deficiency syndrome). HIV infection leads to the generation of HIV-specific thymus-derived (T) lymphocytes in humans and apes. We describe an experimental system permitting the quantitative and systematic analysis of HIV-specific cytotoxic T lymphocytes (CTL). Functional, HIV-specific CTL are obtained by broncho-alveolar lavage (BAL) from the lungs of seropositive patients with lymphocytic alveolitis. These alveolar CTL: (1) recognize and kill HIV-infected alveolar macrophages in vitro under autologous, but not heterologous, conditions; (2) correspond to standard CTL as they express the CD3 and CD8 surface markers, but not the CD4 marker; and (3) are restricted by class I HLA transplantation antigens in their cytotoxic activities. We propose the hypothesis that interactions between HIV-specific CTL and infected macrophages induce major inflammatory reactions in seropositive patients.

Cytotoxicity, Immunologic↗