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PubMed1997

Adsorption of inhalational anesthetics and hydrochlorofluorocarbons on activated carbons as a biological model.

Chlorofluorocarbon (CFC) replacements have recently been used for their lower stability and because they have carbon-hydrogen bonds, which means that their atmospheric lifetime is expected to be much shorter than those of CFCs. The adsorption properties of 1,1,2-trichloro-1,2,2-trifluoroethane (CFC113) and its replacement compounds, 1,1-dichloro-2,2,2-trifluoroethane (HCFC123), 1,1-dichloro-1-fluoroethane (HCFC141b), and 1,1-dichloro-1,2,2,3,3-pentafluoropropane (HCFC255ca) on four kinds of activated carbons were investigated. The amount of CFC and HCFCs adsorbed on the activated carbon was concluded to depend upon the number of chloride and carbon atoms in their molecules. The adsorption isotherms of inhalational anesthetics (halothane, chloroform, enflurane, isoflurane, and methoxyflurane) on the activated carbon were measured to evaluate the action mechanism of inhalational anesthesia. The adsorption isotherms of CFC, HCFC, and the inhalational anesthetics were fitted to the Freundlich equation. The Freundlich constant N was well correlated with the minimum alveolar concentration (MAC) of the inhalational anesthetic: 1 MAC means that 50% of the patients will not move during a surgical operation. The adsorption mechanism of inhalational anesthetics on the surface of the activated carbon is concluded to be similar to the adsorption mechanism on a nerve cell. The anesthesia of CFC replacements can be estimated by the Freundlich constant N of the adsorption isotherms.

Adsorption↗
PubMed1992

Identification of glucose response proteins in two biological models of beta-cell adaptation to chronic high glucose exposure.

High resolution 2-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) combined with computerized analysis of gel images was used to search for proteins whose biosynthesis was induced or repressed in pancreatic islet cells chronically exposed to high glucose in an in situ and a tissue culture model of islet cell adaptation to excessive fuel load. The in situ model involved a 4-day intravenous infusion of either 50% glucose or 0.45% saline solution, followed by islet isolation, [35S]methionine labeling at 3 and 18 mM glucose for both groups, and protein analysis by 2-dimensional SDS-PAGE. The tissue culture model involved a 7-day culture of isolated rat islets in RPMI 1640 with 10% fetal calf serum containing either 3 or 30 mM glucose, followed by radiolabeling and 2-dimensional PAGE of proteins as in the in situ model. A small fraction of about 1.5% of the approximately 2000 identifiable proteins can be characterized as adaptive proteins. Of these altogether 58 proteins in the two models, 5 proteins were demonstrable in both models and two of these (proteins 1526 and 7622) are particularly noteworthy. Protein 1526 (Mr 57,000; pI 5.09) showed the same response pattern in both models and its expression was most enhanced when islets from chronically glucose-infused animals or those cultured for 7 days at 30 mM were radiolabeled at 18 mM glucose. Protein 7622 (Mr 68,000; pI 6.50) (also known as GSP-65; Collins, H.W., Buettger, C., and Matschinsky, F.M. (1990) Proc. Natl. Acad. Sci. U.S.A. 87, 5494-5498) showed a different labeling pattern in the two models: stimulation of [35S]methionine incorporation by 18 mM glucose both in control and experimental islets from the infusion study, but lack of such stimulation of radiolabeling in islets cultured for 7 days at 30 mM glucose in contrast to islets cultured at 3 mM. The experimental strategy and the methodology are evaluated and the significance of the results is discussed. Potentials of the approach and plans for future experiments are considered.

Animals↗
PubMed1989

Prague inbred lines of chickens: a biological model for MHC research.

Evidence for further complexity of the genetic structure of chicken major histocompatibility complex (B) is reviewed, with a historical account showing mutual dependence of the development of an animal genetic model and the growth of scientific knowledge concerning the chicken MHC.

Animals↗