Role of membranes and energy-producing reactions in cellular processing of insulin in primary cultures of rat hepatocytes

Incubation of primary cultures of rat hepatocytes with the local anesthetics, procaine or lidocaine, had little or no effect on insulin uptake or degradation but caused an inhibition of insulin-stimulated glycogenesis. While exposure of cultures to the amines, monodansylcadaverine or CH3NH2, resulted in significant dose-dependent decreases in glycogenesis, only monodansylcadaverine (an inhibitor of receptor clustering) decreased uptake whereas CH3NH2 (a lysosomotropic agent) caused increases in both insulin uptake and degradation. When cells were treated with agents which inhibit glycolysis (NaF, 2-deoxy-D-glucose) or oxidative metabolism (2,4-dinitrophenol, carbonyl cyanide m-chlorophenyl hydrazone, NaN3, antimycin A), pronounced inhibitions of each of the bioactivities studied (syntheses of glycogen, protein, lipid) were observed, but only the glycolytic inhibitors decreased insulin uptake. These results suggest that insulin is internalized by an endocytotic process involving receptor clustering and requiring metabolic energy derived from glycolysis. The post-receptor biosynthetic processes involved in the expression of the biological activities of insulin (syntheses of glycogen, protein, lipid) require energy produced by oxidative metabolism while the degradation of insulin is carried out by nonlysosomal mechanisms which are not energy-requiring.     

Effect of psychotropic substances on the development of alcoholic motivation in noninbred white rats

The experiments have shown the capacity of antidepressant amitriptylin (0.5 mg/kg, i. p.) and tranquilizer phenazepam (0.1 mg/kg i. p.) to normalize the adaptive behaviour and almost completely prevent the development of alcohol motivation in animals with insufficient adaptive behaviour. It was established that in animals initially rejecting alcohol, chronic treatment with these drugs as well as d-amphetamine promoted alcohol motivation. The results obtained have proved our earlier hypothesis that preclinical search for drugs for the prevention and treatment of early stages of alcoholism is possible only in animals pre-selected according to their inclination to experimental alcoholism.     

The reduction of alpha-ketocarboxylic acids and alpha-dicarbonyl compounds with titanium(III) chloride

Thirteen model alpha-ketocarboxylic acids and alpha-dicarbonyl compounds have been observed to be reduced by titanium(III) chloride. The products of these reactions were shown by melting (boiling) points, mixed melting points, derivatives, refractive indices, infrared, and NMR comparisons with authentic compounds or literature information to be the corresponding alpha-hydroxycarboxylic acids or alpha-hydroxyketones.     

Cyclic nucleotide alterations in mixed leukocyte reaction: a preliminary report

Endogenous cyclic adenosine and guanosine monophosphate (cAMP, cGMP) levels were studied in human peripheral blood lymphocytes during mixed leukocyte reactions (MLR). cAMP level was consistently elevated in one-way MLR, with good correlation to 3H-thymidine uptake in these reactions. In contrast, cGMP level was practically unchanged. Irradiation of reacting cell populations resulted in inhibition of cyclic nucleotide phosphodiesterase (PDE) activity. These results suggest that metabolic alterations in cAMP may be associated with immune reactions of cellular recognition.     

Regulation of lung endothelin content by the glucocorticosteroid budesonide.

Intratracheal instillation of Sephadex beads induced a long-lasting inflammation in the rat lung as seen by an increase in lung weights. Repeated instillation enhanced this reaction and increased lung endothelin-1 content 3.5 times. Budesonide given s.c. abolished these effects and even reduced basal endothelin-1 content by 72%. The tissue content of the sensory neuropeptide neurokinin A were unaffected by both treatments. Endothelin has been proposed to play a part in the pathogenesis of bronchial asthma. If it is so, the ability of budesonide to reduce endothelin-1 content could thus be added to the list of beneficial effects of glucocorticosteroids in these conditions.     

Characterization of the self association of Avian sarcoma virus integrase by analytical ultracentrifugation.

Retroviral integration protein (IN) has been shown to be both necessary and sufficient for the integration of reverse-transcribed retroviral DNA into the host cell DNA. It has been demonstrated that self-assembly of IN is essential for proper function. Analytical ultracentrifugation was used to determine the stoichiometry and free energy of self-association of a full-length IN in various solvents at 23.3 degrees C. Below 8% glycerol, an association stoichiometry of monomer-dimer-tetramer is observed. At salt concentrations above 500 mM, dimer is the dominant species over a wide range of protein concentrations. However, as physiological salt concentrations are approached, tetramer formation is favored. The addition of glycerol to 500 mM NaCl, 20 mM Tris (pH 8.4), 2 mM beta-mercaptoethanol significantly enhances dimer formation with little effect on tetramer formation. Furthermore, as electrostatic shielding is increased by increasing the ionic strength or decreasing the cation size, dimer formation is strengthened while tetramer formation is weakened. Taken together, the data support a model in which dimer formation includes favorable buried surface interactions which are opposed by charge-charge repulsion, while favorable electrostatic interactions contribute significantly to tetramer formation.