Effect of different factors modifying the activity of some enzyme systems of the endoplastic reticulum on the sensitivity of cell organelles against the damaging action of chemical agents. I: Interrelations between the activity of some enzyme systems located in endoplasmic reticulum and hepatotoxicity of carbon tetrachloride.

An increased stability of liver lysosomes and mitochondria of burned, dehydrated and tumour-bearing rats has been found in the present investigations. Using biochemical criteria we were able to show that the membranes of liver subcellular particles of these animals become more resistent to the labilizing action of CCl4. The latter effect was confirmed by electron microscopic data. The tumour growth, dehydration and burning of rats as well as sleep deprivation, overheating, lanthanum and ruthenium red have been shown to cause changes in the activity of some enzyme-systems located in endoplasmic reticulum. The protective action of these chemical, pathological and stress factors against CCl4 produced damage to the cell organelles studied is discussed in relation to the activity of the drug metabolizing pathways; biochemical (modifying of some enzyme activity) as well as pharmacological (duration of hexobarbital sleep) data were used as criteria for the activity of these pathways.     

Parallel temperature dependence of contracture-associated enzyme release due to anoxia, 2,4-dinitrophenol (DNP), or caffeine and the calcium paradox.

Hypothermia during calcium-free perfusion of hearts protects them from injury caused by subsequent calcium repletion at 37 C (calcium paradox). Injury to calcium-free hearts is also associated with contracture caused by anoxia, 2,4-dinitrophenol (DNP), or caffeine. This study was done for the purpose of determining whether hypothermia during calcium-free perfusions protects hearts from contracture-associated injury. Langendorff-perfused rat hearts were studied in four experimental groups: I) Anoxia: Thirty minutes of anoxic perfusion at 37 C was followed by thirty minutes of anoxic calcium-free perfusion at 37-18 C. II) Calcium paradox: Five minutes of calcium-free perfusion at 37-18 C was followed by calcium repletion at 37 C. III, IVa) Caffeine or DNP: Five minutes of calcium-free perfusion at 37-18 C was followed by addition of 10 mM caffeine or 1 mM DNP in calcium-free medium at 37 C or, IVb) 1 mM DNP in calcium-free medium at 22 C. Injury was assessed by measurement of serial releases of creatine kinase (CK) in effluents and by cellular morphology. The results show that progressive hypothermia to 22 C during calcium-free perfusion periods produced a progressive reduction of CK release and morphologic evidence of injury due to anoxia, caffeine, or DNP, which closely paralleled protection of hearts from the calcium paradox. Protection from injury in all experimental groups was associated with preservation of sarcolemmal membrane integrity and prevention of cell separations at intercalated disk junctions. It is proposed that weakening of intercalated disks occurs during calcium-free perfusions and may be a cause of mechanical fragility of the sarcolemma. Hypothermia may protect hearts from contracture-associated injury by preserving the integrity of intercalated disk junctions during periods of extracellular calcium depletion.     

Studies of the capillary basal lamina. II. Preparation, chemical composition, andmetobolic properties.

Large amounts of basal laminae material can be extracted by sonic disruption from the capillary tissue of the rete mirabile of the eel swimbladder. The extracted basil laminae material has the same fibrillar pattern as that found in the intact tissue. Thechemical composition is similiar to that of other basil laminae isolated from tissues inmammals, with high content of glycine, proline, hydroxyproline, lysine, and hydroxylysine. The mono- and disaccharide units linked to the hydroxylysine are also present. Of all the pathways of glucose utilization, the 'C-glucose incorporation into the basallamina glycoproteins is the most sensitive to the medium glucose concentration. The glucosyltransferase activity seems stimulated to a plateau value of saturation when the medium glucose concentration is raised from 5 to 20 mm. The 'C-labeled amino acid incorporation into the basal laminae glycoproteins is not affected bythe medium glucose concentration. The results obtained in this study allow for a hypothesis which links the biochemical, morphologic, and functional properties of various typesof basal laminae in normal and hyperglycemic conditions.     

Studies on the effect of systemic administration of sensitizers in guinea-pigs with contact sensitivity to inorganic metal compounds. III. The effect of immunosuppressive agents on enhancing the unresponsiveness of already sensitized animals and an investigation of the action of the epicutaneous test within twenty-four hours

Permanent specific immunological unresponsiveness can be produced in guinea-pigs already sensitive to K₂Cr₂O₇ by the combination of an intravenous injection of 20 mg/kg K₂Cr₂O₇ and an epicutaneous contact with K₂Cr₂O₇ within 24 hr; 2 mg/kg K₂Cr₂O₇ produces only temporary desensitization. Methotrexate and cyclophosphamide for 1 week at the time of the intravenous injection increased the intensity of the suppression but did not prolong the unresponsiveness. Anti-thymocyte serum alone had no effect. A combination of cyclophosphamide and anti-thymocyte serum for 1 week at the time of the intravenous injection prolonged the unresponsiveness for 2 months, but the animals regained sensitivity by 3 months. The addition of prednisolone to this combination, reduced the duration of unresponsiveness produced by a combination of the specific sensitizer, cyclophosphamide and anti-thymocyte serum.

In animals given 20 mg/kg K₂Cr₂O₇ intravenously, removal of the site of epicutaneous application of K₂Cr₂O₇ within 24 hr inhibits the development of specific unresponsiveness. Histological examination of the site of application of the sensitizer reveals microscopic evidence of an inflammatory reaction, although no macroscopic changes can be seen. These findings are discussed in the context of the mechanism of the production of specific immunological tolerance in animals already sensitive.

     

Incorporation of the major outer membrane protein of Neisseria gonorrhoeae in saponin-lipid complexes (iscoms): chemical analysis, some structural features, and comparison of their immunogenicity with three other antigen delivery systems.

We incorporated the major outer membrane protein (PI) of Neisseria gonorrhoeae into immunostimulating complexes (iscoms) and examined some analytical, physicochemical, and immunological properties of these structures. The immunogenicity was compared with that of three other PI-containing structures, i.e., liposomes, outer membrane complexes produced by the bacterium, and protein-detergent-adjuvant complexes. AIPO4 and dioctadecyldimethylammonium bromide were used as adjuvants. Our results show that iscoms are much more immunogenic than liposomes and protein-detergent complexes but are also much more toxic. The localization of PI in iscoms was investigated. Therefore, the chymotrypsin susceptibility of PI in iscoms was tested, and the incorporation of fragments of PI was determined. Amphiphilic fragments of PI were incorporated in iscoms, but hydrophilic and hydrophobic fragments were not. Chymotrypsin degradation of PI in iscoms indicated that the protein is exposed to the environment in a similar manner as PI in outer membrane complexes, i.e., with both termini anchored in the iscom.