Effect of propionate and pyruvate on citrulline synthesis and ATP content in rat liver mitochondria.

Propionate inhibits citrullinogenesis when succinate (plus rotenone) or glutamate are the oxidizable substrates used. Propionate decreases the intramitochondrial concentration of carbamylphosphate by decreasing the ATP content. When the energy supply for citrullinogenesis is provided by an influx of exogenous ATP, propionate is no longer an inhibitor. Pyruvate inhibits citrullinogenesis with glutamate but not with succinate (plus rotenone) as oxidizable substrates. Propionate and pyruvate deplete mitochondrial ATP but probably by different mechanisms.     

Mouse monoclonal antibodies can nonspecifically inhibit the proliferation of human T-cell growth factor-dependent T cells

A large series of mouse monoclonal antibodies was found to inhibit the proliferation of T-cell growth factor (TCGF)-dependent human T-cell blasts as measured by the incorporation of tritiated thymidine. The specificity of the antibody appeared to be irrelevant for inhibition and two T-cell-specific antibodies did not prevent the absorption of TCGF by treated T cells. It is suggested that the antibodies function by the indirect release of suppressor factors by Fc receptor-bearing TCGF-dependent cells.     

Investigation into use of drugs preceding death from asthma.

Copies of death certificates were provided by the Registrar General for all deaths attributed to asthma in persons aged 5 to 34 years which were registered in England and Wales in the last quarter of 1966 and the first quarter of 1967. Information was obtained from the relevant general practitioners about 177 of the 184 subjects, and necropsy data were obtained for 113 of the 124 cases in which a post-mortem examination was known to have been made. Ninety-eight per cent. of the subjects for whom evidence was obtained were known to have been suffering from asthma, and signs of severe asthma (overdistended lungs and small bronchi plugged with mucus) were found in 91% of necropsies (57% of all deaths). Evidence that death might have been due to any other pathological condition was rare. Death was sudden and unexpected in 81% of the subjects (137 out of 171), and 59% of all deaths were referred to coroners. In 39% of cases (67 out of 171) the practitioner had not regarded the patient as suffering from severe asthma in his terminal episode. Corticosteroids and sympathomimetic preparations were the only drugs to have been used by a large proportion of patients. Two-thirds of the patients had received corticosteroids before the terminal episode, but detailed information about their use provided no suggestion that excess use could have been responsible for any large proportion of the deaths. Eighty-four per cent. of the patients were known to have used pressurized aerosol bronchodilators, and several instances of their use in excess were described. Routine inquiries about their use in the hours immediately preceding death were not made, and further evidence is required before their effect can be assessed adequately.     

Reduced hepatic alpha-tocopherol content after long-term administration of ethanol to rats

We have studied the effects of long-term administration of ethanol on the distribution and pharmacokinetics of alpha-tocopherol. In rats fed ethanol (35% of total energy) for 5-6 weeks concentration of alpha-tocopherol in whole liver was reduced by 25% as compared to the pair-fed controls (P less than 0.003). This reduction was significant in the parenchymal cells (28%, P less than 0.004), whereas no significant difference was observed for the nonparenchymal cells. Mitochondrial alpha-tocopherol content was reduced by 55% in the ethanol-treated rats as compared to the controls (P less than 0.002), whereas no significant difference was observed in microsomes, light mitochondria or cytosol. The serum levels of alpha-tocopherol showed no significant difference between the groups. When in vivo labeled chylomicron alpha-[3H]tocopherol was injected intravenously to anesthetized rats, we found a significant increase in serum half-life of alpha-tocopherol in the ethanol-treated group as compared to the controls (P less than 0.025). Hepatic alpha-[3H]tocopherol content was similar in the two groups 24 h after injection.