In vivo inhibition of the tyrosinase of hamster melanoma with sodium diethyldithiocarbamate.

In vivo inhibition of the DOPA-oxydase activity of the soluble tyrosinase fraction of melanotic hamster melanoma is found after i.p. administration of diethyldithiocarbamate, with considerable increase in the content of SH-groups which probably play the role of free radical scavengers.     

The inability of nuclear dehydrogenating clostridia to oxidize bile salt hydroxyl groups.

In a survey of the intracellular bile salt oxidoreductase activity in fecal bacteria, 16 strains of nuclear dehydrogenating clostridia and 2 strains of non-nuclear dehydrogenating C. paraputrificum were demonstrated unable to oxidize cholate at any of the 3 OH groups. Since nuclear dehydrogenation at the delta-1 and delta-4 position requires a 3-oxo precursor steroid, it appears that these organisms require the presence of a 3 alpha-hydroxysteroid dehydrogenating organism for nuclear dehydrogenation.     

Influence of alpha-MSH and ACTH on cortical bone remodelling in hypophysectomized rats.

Hypophysectomy increases both periosteal resorption and endosteal apposition along the femur diaphysis in rat. Administration of alpha-MSH decreased the periosteal resorption but had no effect on the endosteal apposition. ACTH had only minor effects on the endosteum. Thus, alpha-MSH and ACTH, in the doses used, have different effects on cortical bone in rat. The effect of alpha-MSH on cortical bone could be an effect of the hormone alone or by its stimulation of other factors.     

Exchange of tritium from randomly tritiated taurocholate by microbial bile salt oxidoreductases.

Tritium distribution on randomly labelled taurocholate (TC) was estimated at 28%, 4%, 1% and less than 0.5% on the hydrogens opposite the 3alpha-, 7alpha- and 12alpha-OH groups and taurine moiety respectively. Anomalously, C. perfringens 3alpha-hydroxysteroid dehydrogenase (3alpha-HSDH) catalyzed tritium loss of 36% on formation of 7alpha-, 12alpha-dihydroxy-3-keto-5beta-cholanoate, implying additional losses of tritium at other sites by this enzyme.     

HCO-3-ATPase activity distribution in rat liver cell fractions prepared by zonal centrifugation.

Plasma membrane sheets prepared by zonal centrifugation of a premicrosomal pellet obtained from a rat liver homogenate are devoid of HCO-3-ATPase activity. Since the microsomal fraction is also lacking in this ATPase activity, it can be concluded that the HCO-3-ATPase is not involved in the secretion of HCO-3 into bile.     

Effect of low density lipoprotein and high density lipoprotein on sodium dodecyl sulphate precipitation of very low density lipoprotein from human serum.

In the presence of low density lipoprotein, the sodium sodecyl sulphate(SDS)-very low density lipoprotein(VLDL) complex sedimented, while in the presence of high density lipoprotein the complex floated. This SDS-VLDL aggregate floats at serum triglyceride to cholesterol ratio of 0.7-0.9 and sediments at a ratio of 0.2-0.5.     

Pigment granules in choroidal melanophores of the albino goldfish.

Pigment granules in choroidal melanophores of the albino goldfish contained fine particulate materials which were in various degrees aggregated in clumps. Tyrosinase was considered to be present in an inhibited state in these pigment granules.     

Increased susceptibility of Trypanosoma lewisi infected, or decomplemented rats to Salmonella typhimurium.

Rats infected with Trypanosoma lewisi or decomplemented by injection of cobra venom factor or complement activating factor of trypanosomes were found to be more susceptible to infection with Salmonella typhimurium. Decomplemented rats subsequently infected with T. lewisi developed higher blood parasitemia than did normal T. lewisi infected rats.     

Effect of electroconvulsive treatment on serum dopamine-beta-hydroxylase activity in man

The activity of dopamine-beta-hydroxylase was measured in the serum before and immediately after electroconvulsive treatments. No significant difference was observed, suggesting that the seizures did not cause an increase in the peripheral sympathetic tone.