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Biomedical subjects

S M Barlow

Publications and source records attributed to S M Barlow.

9 recordsLinked to original sources
PubMed1979

Congenital malformations and other reproductive hazards from environmental chemicals.

From a number of disasters which have already occurred throughout the world, it is known that the reproductive process in both animals and man may be severely affected by chemicals. The range of effects that might occur include not only foetal death or malformation, but also effects on the subsequent development, behaviour, intelligence and reproductive capacity of offspring which appear otherwise normal at birth. The special sensitivity of the foetus to some environmental carcinogens is also discussed. Some of the problems in screening for such effects in animals are mentioned along with the need for adequate monitoring programmes to detect reproductive toxicity both from industrial exposure to chemicals and from more general environmental exposure.

Abnormalities, Drug-Induced↗
PubMed1979

Prevention by diazepam of adverse effects of maternal restraint stress on postnatal development and learning in the rat.

Rats on days 12--14 of pregnancy were treated with restraint stress alone (9h daily), restraint stress plus diazepam (1 mg/kg, twice daily), diazepam alone, or left as untreated controls. Postnatal development and behaviour was assessed on a wide-ranging battery of tests. Offspring of mothers subjected to restraint stress alone were significantly retarded on a number of developmental measures including growth, ear-opening, cliff avoidance response, auditory startle response and mid-air righting reflex. When adult these offspring also showed significantly impaired learning ability in a swimming maze. However, the rate of development and learning ability in the restraint plus diazepam or diazepam alone groups was comparable to or slightly advanced of that in untreated controls. It is concluded that concurrent administration of a low dose of the tranquiliser diazepam during restraint stress prevents the adverse postnatal effects of maternal restraint stress.

Animals↗
PubMed1979

Comparison of lipid status in the hearts of piglets and rats on short term feeding of marine oils and rapeseed oils.

A series of 4 experiments with piglets and one experiment with rats has been conducted to establish the cardiac lipid status of weanling (3 weeks old) male animals fed fats with different contents of docosenoic fatty acids. Experimental fats were rapeseed oil (RSO) (48.0% 22:1), refined fish oil (RFO) (14.6% 22:1), partially hydrogenated fish oil (PHFO) (14.3% 22:1) and lard (0% 22:1) combined with sunflower seed oil (SFO) in different proportions in diets with 21% total fat. Lipidosis could not be detected in piglets as increased heart weights, by chemical assay for myocardial contents of triglycerides, or by accumulation of docosenoic fatty acids or nonesterified fatty acids (NEFA). In rats, diets with RSO at a level of 16% increased myocardial triglyceride and docosenoic fatty acid contents about 7 times while the effect on cardiac NEFA was inconsistent. Histological examinations of the hearts revealed stainable intracellular fat droplets in some piglets fed 16% RSO for 8 to 13 days, but not after 2, 4 and 6 and 16, 19 and 22 days of feeding. After 10 days of feeding, mild to moderate histological lipidosis was found in piglets fed diets containing 2% or more of 22:1 fatty acids, with no significant difference between RSO, RFO and PHFO in this respect. The same diets in rats gave about 5 times more histological lipidosis than in piglets. This is attributed to a difference in species response, the rat reacting in a more pronounced manner than the piglet. The cardiac lipidosis no-effect level in piglets corresponded to a daily intake of docosenoic fatty acids of 0.4 g per kg body weight. Mild lipidosis was also found in a few animals on docosenoic acid-free diets.

Animal Feed↗
PubMed1979

Plasma corticosterone responses to stress following chronic oral administration of diazepam in the rat.

The effect of daily, oral administration of diazepam on plasma corticosterone responses to stressors of varying intensity was investigated. In rats exposed to the mild stress of noise, diazepam, 10 mg kg-1 but not 1.0 or 0.1 mg kg-1, reduced plasma corticosterone concentrations by 30% in comparison with controls. However, in rats exposed to the more severe stressors, foot-shock or immobilization, none of these doses of diazepam reduced plasma corticosterone responses. In unstressed rats, diazepam 10 mg kg-1 raised plasma corticosterone concentrations. It is suggested that plasma corticosterone concentrations are not a reliable indicator of the tranquillizing effect of diazepam during stress.

Animals↗
PubMed1977

Erucic acid in edible fats and oils: a collaborative study on determination by open-tubular (capillary) gas-liquid chromatography.

An open-tubular (capillary) column gas-liquid chromatographic method for the determination of the specific isomer of docosenoic acid known as erucic acid (cis-docos-13-enoic) in the presence of other docosenoic acid isomers present in partially hydrogenated marine oils has been evaluated collaboratively. With wall-coated columns and the liquid phase SILAR-5CP, nine laboratories successfully analysed mixtures of partially hydrogenated marine oils, corn oil and rapeseed oil with a nominal content of 10% erucic acid, compatible with the regulations of the European Economic Community.

Chromatography, Gas↗
PubMed1976

Electron paramagnetic resonance studies of cytochrome P-450 and adrenal ferredoxin in single whole rat adrenal glands. Effect of corticotropin.

Low and high spin ferric cytochrome P-450 and reduced adrenal ferredoxin (adrenodoxin) have been directly studied by EPR techniques in whole rat adrenal glands. The spectra obtained correspond closely to those obtained from sub-cellular fractions except in the case of low spin ferric cytochrome P-450, where there are differences in the shape of the g = 2.41 line. The relative magnitudes of these peaks in anaerobic and aerobic rapidly frozen adrenals from control and corticotropin stimulated hypophysectomised rats were used to investigate the control and rate limiting steps in adrenal steroid biosynthesis via cytochrome P-450. All adrenals showed a close to maximal level of reduced adrenodoxin and aerobic and anaerobic glands from control rats and aerobic glands from corticotropin stimulated rats showed similar quantities of low spin ferric cytochrome P-450. On anaerobiosis the quantity of low spin ferric cytochrome in adrenals from corticotropin stimulated rats dropped to 30--40% of the aerobic level. Treatment of the rats with cycloheximide prior to administration of corticotropin prevented these changes. Approximately 0.4% of the total cytochrome P-450 was high spin ferric in control adrenals and in aerobic stimulated adrenals this rose to approximately to 0.6%. These results demonstrate that association of substrate with cytochrome P-450 is the rate limiting step in adrenal steroidogenesis via cytochrome P-450. It is suggested on the basis of these and mitochondrial optical and EPR experiments that the limiting step being observed is cholesterol binding to cholesterol side chain cleavage cytochrome P-450, and that the rate of this association is stimulated by corticotropin.

Adrenal Glands↗