Metabolism in Porifera. VII. Conversion of [7,7-3H2]-fucosterol into calysterol by the spongeCalyx niceaensis

Summary The spongeCalyx niceaensis metabolizes administered [7,7-³H₂]-fucosterol to produce labelled calysterol, the principal sterol component of the sponge, possessing the unique feature of a cyclopropene ring bridging C_23,24.     

The influence of several sterols on the conversion ofβ-sitosterol into cholesterol in the cockroach

Zusammenfassung Die Umwandlung von-Sitosterol in Cholesterol in der SchabeBlattella germanica L. wird durch bestimmte Sterine mit unnatürlichen Seitenketten gehemmt. Anhäufung von zwei verschiedenen Metaboliten wurde festgestellt.

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This work was supported by a grant from the National Council for Agricultural Research TNO.     

Metabolism in Porifera. X. On the intermediary of a formamide moiety in the biosynthesis of isonitrile terpenoids in sponges

Summary Feeding the spongeAxinella cannabina with labelled axamide-1, the presumptive precursor of axisonitrile-1, resulted in the recovery of nonradioactive isonitrile.     

Fucosterol-24,28 epoxide and 28-Oxe-β-sitosterol as possible intermediates in the conversion ofβ-sitosterol into cholesterol in the locustLocusta migratoria L.

Résumé Le CriquetLocusta migratoria L. transforme l'époxyde-24, 28 du fucostérol en cholestérol; le desmostérol est un intermédiaire. Ce même Insecte ne transforme pas spécifiquement le céto-28 -sitostérol en cholestérol; on observe dans ce cas une inhibition de la désalkylation en 24 du -sitostérol. Un schèma de dégradation du -sitostérol parLocusta migratoria est présenté.     

Ascorbic acid and cholesterol: Effect of graded oral intakes on cholesterol conversion to bile acids in guinea-pigs

Summary A significant correlation between liver ascorbic acid (AA) and total bile acids or liver bile acids has been established in guinea-pigs by direct determination of the bile acids, confirming an earlier hypothesis. The oxidation of cholesterol to bile acids is dependent on the AA status, but it cannot be further stimulated by AA when the animals are already on an adequate intake of the vitamin. This suggests that AA has a hypocholesterolaemic effect over a limited range of AA status.     

Effect of aflatoxin B1 on the incorporation of14C-acetate into cholesterol by rat liver

Résumé L'administration d'aflatoxine B₁ (2 et 5 mg/kg, i.p., 24 h avant le sacrifice) a résulté en un abaissement de 80% de l'incorporation du l-¹⁴C-acétate en cholestérol par des coupes de tissu de foie. Le même traitement n'a pas altéré l'activité des drug metabolizing enzymes au niveau des microsomes du foie.     

Metabolism in porifera. VII. Conversion of [7,7-3H2]-fucosterol into calysterol by the sponge Calyx niceaensis

The sponge Calyx niceaensis metabolizes administered [7,7--(3)H2]-fucosterol to produce labelled calysterol, the principal sterol component of the sponge, possessing the unique feature of a cyclopropene ring bridging C23,24.     

Biogenesis of rifamycins. The conversion of rifamycin B into rifamycin Y

Riassunto È stata studiata la biogenesi della rifamicina Y, prodotta accanto alla rifamicina B da culture diS. mediterranei. I dati riportati dimostrano che la rifamicina Y deriva dalla rifamicina Be che la sua produzione dipende dalla concentrazione di fosfati nel terreno di cultura.

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Presented in part at the Vth International Congress of Chemotherapy, Wien, 26 June 1967.     

Lack of conversion of C29-phytosterols to cholesterol in the khapra beetle,Trogoderma granarium Everts

Summary Metabolic studies in which³H-sitosterol,³H-stigmasterol, and¹⁴C-desmosterol were administered by feeding and injection to the khapra beetle,Trogoderma granarium Everts, provided strong evidence that this insect is unable to dealkylate phytosterols and convert them to cholesterol.     

Desmosterol as a common intermediate in the conversion of a number of C28 and C29 plant sterols to cholesterol by the tobacco hornworm

Résumé Manduca sexta (Johannson) est capable de transformer 7 phytostérols en cholestérol. Ainsi, cet insecte peut déalcoyler le - et le-méthyl de même que les groupes méthylène et éthylidènes du carbone 24 et peut hydrogéner la double liaison 22, 23. Quand ces stérols sont combinés au 20, 25-diazacholestérol, on a constaté dans tous les cas que la transformation en cholestérol s'effectue par l'intermédiaire commun, le desmostérol.     

Metabolism of C19-steroids in testicular tissue of the newtTriturus vulgaris,during and after breeding

Summary Incubation studies with testicular homogenates ofTriturus vulgaris showed that testosterone was quantitatively the most important metabolite of dehydroepiandrosterone and androstenedione during breeding. After breeding the recovery of testosterone declined. This suggests that 17-hydroxysteroid dehydrogenase may be regulated for the needs of testicular androgen production.     

Alteration of erythrocyte (see article) -ATPase by replacement of cholesterol by desmosterol in the membrane.

Cholesterol of red blood cells (RBC) is readily exchanged by desmosterol and vice versa. The resulting alteration in the sterol composition influences the specific (Na+ plus K+)-ATPase activity. It is suggested that this effect is due to an altered membrane fluidity.     

Metabolism of the normal cardiovascular wall. 1. Utilization of glucose by arteries and veins

Riassunto Il destino del glucosio generalmente mercato¹⁴C in diverse arterie e vene del cane é stato studiato con l'uso di una tecnica quantitativa di radiocromatografia su carta.I risultati non solo mostrano che nella parete arteriosa ha luogo una notevole glicolisi aerobica ed anaerobica, ma anche chiaramente indicano che una percentuale relativamente alta di glucosio viene trasformata in amino acidi (probabilmente attraverso il ciclo degli tricarbossilici) ed in grassi.Quantitativamente è stato osservato che il tessuto arterioso utilizza maggiore quantità di glucosio di quello venoso e che tale differenza è tanto maggiore quanto più i vasi sono periferici.

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Investigation was conducted during tenure of Special Research Fellowship (No. 11091) U.S. Public Health Service.     

The effect of skim milk on plasma cholesterol in rats.

From the 15th day of birth, newborn rats were offered rat chow mixed with water or skim milk. The former also received tap water, the latter skim milk. In the latter group, plasma cholesterol was lowered in 43- and 64-day-old males and in 64-day-old females.     

Studies on chemotherapy of parasitic helminths (IX). Effects of praziquantel on the motility of various parasitic helminths and isolated host tissues

Summary Praziquantel (PQ) caused spastic and/or paralytic actions on the motility of various parasitic helminths and isolated host tissue preparations, through a neuropharmacological mechanism.     

Metabolism of hydrazines and hydrazides by the intestinal microflora

Summary Intestinal microorganisms are able to effect the metabolic reductive fission of hydrazines but not hydrazides during incubation in vitro.We thank the Medical Research Council for a studentship (to GCB).     

Studies on the late-pre-beta-lipoprotein of human serum.

Very low density lipoprotein (VLDL) isolated from 3 healthy normolipidaemic subjects had a raised VLDL cholesterol to triglyceride ratio. The VLDL fractions gave 2 pre-beta-bands on agarose gel electrophoresis. Family study of the subjects appears to indicate sex linkage of this trait and a possible polygenic type of inheritance.