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Biomedical subjects

R Gay

Publications and source records attributed to R Gay.

At least 73 records · Page 4Linked to original sources
PubMed1980

Chinese hamster lung cells synthesize and confine to the cellular domain a collagen composed solely of B chains.

The acid-soluble collagen extracted from cultured Chinese hamster lung (CHL) cell layers has been isolated after limited pepsin digestion and differential salt fractionation. Polyacrylamide gel electrophoresis of this material under denaturing conditions showed the presence of collagen chains with an apparent molecular mass of 120,000 daltons both before and after reduction, indicating the absence of interchain disulfide bonds in the native molecule. When chromatographed on CM-cellulose under denaturing conditions, the majority (> 90%) of the CHL cell layer collagen chains eluted as relatively basic components slightly before the human alpha 2(I) chain and coincident with the human B chain. In addition, the CM-cellulose elution profiles of the cyanogen bromide peptides derived from the human B chain and from the CHL cell layer chain were essentially identical. Examination of CHL cells in culture by using affinity-purified antibody to human B chain revealed this collagen to be localized in an extracellular matrix surrounding the cells. Furthermore, analysis of the culture medium indicated the absence of any comparable collagen chain. These data provide additional evidence for the existence of a molecular form of collagen composed solely of B chains and suggest that this molecular form of collagen has an unusual affinity for the cell layer in this system.

Animals↗
PubMed1980

Immunohistochemical localization of Type III collagen in the dentin of patients with osteogenesis imperfecta and hereditary opalescent dentin.

The immunohistochemical localization of Type III collagen was studied in the dentin from nine patients with dominantly inherited osteogenesis imperfecta (O.I.) and six patients with hereditary opalescent dentin (H.O.D.). The most consistent localization of Type III collagen was found in patients with O.I. Among these patients an indirect relationship existed between the severity of dentinal involvement and the presence of Type III antibody localization. Although a similar but less intense staining could be observed in some cases of H.O.D., the severity of dentinal alterations in H.O.D. was not correlative to the quantitative presence of material reacting with antibodies to Type III collagen. These observations further indicate that O.I. is not only clinically, but biochemically, a heterogeneous condition.

Adolescent↗
PubMed1980

Menadione reductase from Clostridium tyrobutyricum.

Menadione reductase (EC 1.6.99.2) has been purified 67-fold from Clostridium tyrobutyricum extracts. The molecular weight was found to be 60 000 and the prosthetic group was identified as FMN on the basis of the enzymatic analysis data. The binding of FMN to the menadione dehydrogenase apoenzyme was relatively weak with an apparent Km value of 2.5 x 10(-6) M. The enzyme exhibited group substrate specificity for compounds with a quinoid structure; naphthoquinones and benzoquinones without long carbon chain substituents were the most active. The reactivity of the enzyme with vitamin K1, coenzyme Q6, and cytochrome c was negligible and, with 2,6-dichlorophenol indophenol, relatively low. It was shown that the enzymatic reduction of menadione with the participation of either NADH or NADPH takes place by a "Ping-Pong" mechanism. The enzyme catalyzed the oxidation of NADH and NADPH at equal rates and was inhibited by dicumarol and p-chloromercuribenzoate.

Clostridium↗
PubMed1980

[Regulation of artificial ventilation in adult respiratory distress syndromes].

Progress in recent years in functionnal investigations of the ventilated patient has made it possible to refine the regulation of artificial ventilation in particular in patients with lesional oedema. The best ventilatory regimen is that which ensures adequate alveolar ventilation at the price of the least mechanical and haemodynamic difficulties. It is also that which ensures the best oxygen transfer and hence to reduce alveolo-arterial oxygen difference. It is now known that the reconstitution of functional residual capacity (FRC) is the essential step. The use of positive pressure at the end of expiration (PEEP) generally makes it possible to achieve this aim. Alveolar function in high critical opening pressure zones requires levels of PEEP for which the maintenance of constant cardiac output is necessary. This may be obtained by combining blood volume expansion with the effect of positive inotropic drugs. Estimation of VD/VT ratio, calculation of P(A - a)O2 and of oxygen transfer indices such as P(a/A)O2 may be used to assess the efficacy of exchanges. Cycle to cycle surveillance of quasi thoracopulmonary compliance offers information concerning the improvement in FRC.

Adult↗
PubMed1980

Synthesis of macromolecules in synchronously grown Arthrobacter.

The synchronous growth of Arthrobacter has not yet been studied. We have shown that synchrony of A. crystallopoietes and A. globiformis cultures can be achieved in a liquid synthetic medium by inoculating a fresh medium with cells taken from an advanced stationary phase culture. DNA content measurements and pulsed incorporations of tritiated thymidine have been used to show that DNA synthesis occurs in a stepwise manner in these synchronized cultures. The use of absorbance of cultures as a monitor of synchronized cell growth was especially useful since cells did not separate during the exponential phase. The breaks in the absorbance versus time curve indicated a slow-down in mass synthesis. Protein and RNA synthesis occurred in two waves during the time necessary for a doubling of cell mass: a first increase was observed at the beginning of the DNA replication; after a slow-down, a second sharp increase occurred after the replication of DNA. These results are discussed in relation to previous data on the existence of a differential transcription during the development of A. crystallopoietes.

Arthrobacter↗
PubMed1979

[Severe drug complications: current prevalence amongst patients admitted to adult intensive care units (author's transl)].

A retrospective study involving nine teaching hospital mixed intensive units provided information concerning severe drug complications amongst patients admitted to these departments over the past ten years. Amongst a total of 63717 patients admitted, there were 1132 drug complications (1.8%) without any predominance in terms of sex. Mortality was high (252 patients, i.e. 22.2%), being all the greater in older patients. Details concerning the various drug complications are given, the most common being anaphylactic shock and haemorrhage due to anticoagulants. These statistics are compared withthose already published by hospital departments of internal medicine.

Age Factors↗
PubMed1979

Immunohistochemical demonstration of basement membrane collagen in normal human skin and in psoriasis.

Antibodies prepared against the collagen C-chain derived from human placenta specifically strain the epidermal basement membrane of normal human skin as well as the basement membrane surrounding the skin appendages and capillaries. Using the antibodies, it was observed that all basement membranes in untreated psoriatic plaques appear fragmented and separted into several layers. The results suggest that psoriatic lesions are associated with a general loss of basement membrane integrity which may play a crucial role in the pathogenesis of the disease.

Antibody Specificity↗
PubMed1979

[The Davenport diagram and the international system of units].

The implantation of the international system of units in medical science leads to revising the Davenport diagram. This diagram has been widely used for 20 years as a system displaying the variations in acid-base equilibrium. In order to conserve its familiar aspect the coordinates are: a pH abscissa complete with a scale of H+ ion concentrations (nmol.l-1) and an ordinate using real plasma HCO-3 concentrations. The isobars of PCO2 are reconstructed for whole and semi-whole kilopascal values (kPa). The real plasma buffer lines are reconstructed for 3, 6 and 9 n.mmol.-1 of monomeric hemoglobin which are the nearest whole values of 5, 10 and 15 g of Hb/100 ml. The diagram is calculated for 37 degrees C and the constants used for pK' and aCO2 are the most recently suggested values.

Acid-Base Equilibrium↗