Metabolism in Porifera XII. Further informations on the biosynthesis of 3β-hydroxymethyl-A-nor-steranes in the spongeAxinella verrucosa

Summary Direct incorporation and cold trap experiments suggest that cholest-4-en-3-one is an intermediate in the conversion of cholesterol into 3-hydroxymethyl-A-nor-cholestane in the marine spongeAxinella verrucosa. Cholest-4-en-3-one is further transformed by the sponge into cholest-4-en-3-ol, 5-cholestan-3-one and 5-cholestan-3-ol; these compounds arise from side reactions, which are not part of the major metabolic route leading to 3-hydroxymethyl-A-norsteranes.     

The effect ofβ-adrenergic stimulation and blockade on the efflux of PGE1-like material from the isolated perfused rabbit heart

Summary Prostaglandin (PG) release was measured from the isolated perfused rabbit heart. The effects of -adrenergic stimulation and blockade suggest that PG synthesis is regulated in part by adrenergic mechanisms.     

Effects of aluminium hydroxide on restraint-induced and restraint delay-induced gastric ulceration in rats

Summary Rats given aluminium hydroxide after cold-restraint stress but before the post-stress delay period, ulcerated significantly less severely and less frequently than rats given the drug before cold-restraint stress or those given water at either time period. Both aluminium hydroxide treated groups exhibited less ulceration than non-drug groups. These data suggest profound parasympathetic and hence, gastric acid, involvement in restraint delay-induced ulceration in rats.     

A microanalysis of colloid osmotic pressure

Summary A needle type of colloid osmometer has been devised with special attachments which made it useable with 3-l samples. It has been used in oncometry of fresh water teleosts to give the following results: 5.1±1.0 mm Hg for goldfish, 5.2±0.71 mm Hg for carp, and 14.3±0.75 mm Hg for eel.This study was supported in part by Research Grant 387036 from the Ministry of Education of Japan.invited to National Institute of Physiological Sciences, Okazaki, Japan.     

Studies on muscle fibre splitting in skeletal muscle

Summary Autoradiographic, stereological and histological studies have been carried out to determine the origin of muscle fibre splitting which supposedly occurs during muscle hypertrophy. The results obtained clearly indicate that the supposedly split fibres are a transient response probably derived from satellite cells and are not derived from pre-existing fibres by true splitting. Similarly, increases in muscle fibre size are not achieved by recruitment of satellite structures as indicated by lack of myonuclear recruitment.Acknowledgment. This work was carried out with the aid of a grant from the Medical Research Council of Great Britain. The authors are grateful for the excellent technical assistance of Miss H. Caulton, M.J. Wild and M. Fenner.     

Polyacetylenes from the spongePetrosia ficiformis found in dark caves

Summary Several high molecular weight polyacetylenes have been isolated from the spongePetrosia ficiformis found in dark caves. These compounds are related to, but different from, the polyacetylenes isolated from the same sponge living in its usual habitat.This work is a part of the Progetto finalizzato per l'Oceanografia e i Fondi Marini, CNR, Roma.The authors thank Mr G. Scognamiglio for the HPLC work, Mr C. Di Pinto for the NMR spectra and Mr G. Villani for the collection of the sponge.     

Effects of ACTH and diabetes on phospholipid metabolism in adrenal mitochondria.

Incorporation of 32P into adrenal mitochondrial phospholipids (PL) incrased in ACTH-treated rats, but it decreased in diabetics, inspite of the fact that these animals showed adrenal overacity. Since diabetics did not show increased 11 beta-hydroxylation. as opposed to ACTH-treated rats, it is suggested that the stimulation of this enzyme activity by exogenous ACTH is related to an increased turnover of PL at the mitochondrial membrane. The process is impaired in diabetics and prevents the stimulation of 11 beta-hydroxylation.