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Biomedical subjects

R Gay

Publications and source records attributed to R Gay.

At least 55 records · Page 3Linked to original sources
PubMed1983

[Effect of growth phase and composition of the medium on the rate of biosynthesis of NADH: rubredoxin oxidoreductase in Clostridium acetobutylicum].

Among the three strains of Clostridium acetobutylicum we investigated: NRRL 592, NCIB 619 and ATCC 824, only the last was shown to contain a NADH: rubredoxin oxidoreductase activity. We report that the biosynthesis rate of this enzyme fluctuated in the proportions of 1 to 50 according to the growth phase and medium composition. These variations reflect a mode of regulation adjusted to the metabolism of bacteria.

Clostridium↗
PubMed1982

[Oesophagitis during mechanical ventilation].

Twenty-one patients whose condition required mechanical ventilation with nasogastric intubation were investigated for oesophagitis before the 3rd day and on the 15th day of treatment, including endoscopy and biopsy. Lesions of oesophagitis were detected in 14 cases during the initial examination and in 19 cases on the second endoscopy. The course of the lesions varied from one patient to another and appeared to be unrelated to the course of the primary disease. Oesophagitis in these patients is probably due to frequent episodes of gastro-oesophageal reflux encouraged by cough, impaired consciousness and the presence of a tube. Reflux may also be the cause of inapparent and recurrent lung aspiration.

Adult↗
PubMed1982

Multiple collagen gene expression with type III predominance in rat mucosal keratinocytes.

Collagen synthesis in serially propagated cultures of rat mucosal keratinocytes (line RTK-I) was investigated. Analysis of biosynthetically labeled cell and media proteins retrieved after limited pepsin digestion revealed seven or eight collagen chains originating from four distinct collagens (types I, III, IV, V). Type III collagen was identified as the predominant species based on its electrophoretic and chromatographic behavior in the reduced and unreduced states, on the peptide pattern generated by limited cleavage with CNBr and with trypsin, and on the immunofluorescent detection of intracellular, collagen type III-reactive material. Evidence for the synthesis of two type IV collagen chains (155 k and 160 k after limited pepsin digestion) was provided by immunofluorescent and electrophoretic studies. Type V collagen was revealed by immunofluorescence, and two, possibly three, component chains were resolved in native type V collagen isolated from the harvest medium. Type I collagen, identified by comigration with authentic carriers, was a constant but quantitatively variable synthetic product. This study provides evidence that keratinocytes produce collagens normally found in mesenchymal matrices (type I and III) in addition to collagens characteristic of basement membranes (type IV) and of pericellular structures (type V). These findings reveal a hitherto unrecognized complexity and heterogeneity of the collagens synthesized by a highly differentiated epithelial cell type.

Animals↗
PubMed1982

Acetone and Butanol Production by Clostridium acetobutylicum in a Synthetic Medium.

The effect of the component concentrations of a synthetic medium on acetone and butanol fermentation by Clostridium acetobutylicum ATCC 824 was investigated. Cell growth was dependent on the presence of Mg, Fe, and K in the medium. Mg and Mn had deleterious effects when in excess. Ammonium acetate in excess caused acid fermentation. The metabolism was composed of two phases: an acid phase and a solvent one. Low concentrations of glucose allowed the first phase only. The theoretical ratio of the conversion of glucose to solvents, which was 28 to 33%, was obtained with the following medium: MgSO(4), 50 to 200 mg/liter; MnSO(4), 0 to 20 mg/liter; KCl, 0.015 to 8 g/liter (an equivalent concentration of K was supplied in the form of KH(2)PO(4) and K(2)HPO(4)); FeSO(4), 1 to 50 mg/liter; ammonium acetate, 1.1 to 2.2 g/liter; para-aminobenzoic acid, 1 mg/liter; biotin, 0.01 mg/liter; glucose, 20 to 60 g/liter.

Journal Article↗
PubMed1981

[Evaluation of a method for the measurement of static total compliance (Siemens Elema LMC 940 calculator)].

The aim of the present study was to validate the method for the measurement of total compliance proposed by Siemens Elema. The pressure and flow signals of the Servo 900 respirator are treated by an LMC-940 calculator. 1 - A study with a pulmonary model was used to evaluate the applicability of the measuring techniques used by the calculator. Tele-inspiratory alveolar pressure is accurately assessed for successive measurements of inspiratory resistance if the interruption of inspiratory flow is at least 0.3 seconds. Tele-expiratory alveolar pressure is accurately interpreted even if flow at the end of expiration is not nil, as long as airway resistance remains constant. The error in measurement of tidal volume depends in part upon the compression relaxation effect of gases in the circuit. The device used to compensate for this effect is effective up to a tele-inspiratory pressure of 1.96 kPa (20 cm H2O). Beyond this pressure, tidal volume is overestimated. The error is small, if the time after which the flow is integrated is 130 ms. For shorter periods, the correction is less satisfactory. 2 - A study in eight patients was used to assess the validity of 38 measurements of Ctot on the respirator in comparison with contemporary measurements made under static conditions using a syringe. A highly significant linear correlation was seen between values of Ctot obtained by the two methods: Ctot syringe = 0.94 X Ctot calculator = 0.55 ml.cmH2O-1. (n = 38; r = 0.95; p less than 0.001). The mean error of the calculator for a given reference value was 0.099 l.kPa-1 (9.65 ml.cmH2O-1). There was a closer relation for variations in Ctot recorded by the two methods. Variations were always in the same sense, and their correlation was highly significant (n = 19; r = 0.98; p less than 0.001). Such a method for the surveillance of compliance is extremely easy. The accuracy of absolute values for Ctot is limited but it is a reliable method for following variations in compliance and hence the effects of treatment.

Evaluation Studies as Topic↗
PubMed1980

[Variations in cyclic AMP level and specific activities of adenylate cyclase and cyclic AMP phosphodiesterase during the cell cycle of an Actinomycete (author's transl)].

The variations in the concentrations of intra- and extracellular cyclic AMP and in he specific activities of adenylate cyclase (EC 4.6.1.1) and cyclic AMP phosphodiesterase (EC 3.1.4.17) have been monitored in synchronized cultures of Nocardia restricta, a prokaryote belonging to the group of Actinomycetes. At the beginning of the cell cycle, during a first period of RNA and protein synthesis, there is an increasing synthesis of adenylate cyclase which can be suppressed in the presence of chloramphenicol or rifampicin. Simultaneously, the specific activity of cyclic AMP phosphodiesterase decreases and the concentrations of intra- and extracellular cyclic AMP rise. After the end of DNA replication, during a second period of RNA and protein synthesis, the specific activity of cyclic AMP phosphodiesterase increases; during the same time, the specific activity of adenylate cyclase and the level of intracellular cyclic AMP drop. It appears that the overall metabolism of cyclic AMP is coordinated so that the cyclic AMP level will be high at the beginning of DNA replication and will fall thereafter. The results are discussed in comparison with known data about the variations of cyclic AMP during the cell cycle of mammalian cells in cultures.

3',5'-Cyclic-AMP Phosphodiesterases↗