PubMed Health⌕ Search

Biomedical subjects

B J Simpson

Publications and source records attributed to B J Simpson.

26 records · Page 2Linked to original sources
PubMed1987

Inhibin bioactivity in human testicular extracts.

Inhibin bioactivity was measured in human testicular extracts by a sensitive sheep pituitary cell bioassay. The relationship between testicular inhibin bioactivity, daily sperm production (DSP) and plasma concentrations of FSH, LH, testosterone and oestradiol were examined. The mean level of testicular inhibin bioactivity was 4.4 +/- 1.3 U/g (mean +/- SD) with a significantly lower value in those who received radiotherapy (3.2 +/- 1.4 U/g) than in the untreated group (4.8 +/- 1.1 U/g). In contrast to the rat, human testicular inhibin bioactivity was not significantly correlated to FSH or DSP. These findings suggest that inhibin may have a complex role in normal and/or pathological testicular function.

Aged↗
PubMed1975

Decontamination procedures for skin exposed to phenolic substances.

Spraying or swabbing with a mixture of polyethylene glycol 300/industrial methylated spirits (PEG-300/IMS) (2:1 by volume) has been shown to substantially reduce mortality, systemic effects, and skin burns resulting from skin contamination by phenol, cumene hydroperoxide, or phenol/acetone cleavage product. The skin-damaging potentials of sodium hydroxide and sulfuric acid have also been investigated. PEG-300/IMS(2:1 by volume) mixture was found, in rats, to be slightly less effective than water as means of decontamination. The PEG-300/IMS mixture has been shown not to cause eye irritation, and so should not present a hazard where this mixture is used as a decontaminant spray.

Acetone↗
PubMedDate not supplied

The carcinogenic response in mice to the topical application of propane sultone to the skin.

The carcinogenic effects of limited and repeated skin applications of propane sultone were investigated in three strains of mice, CF1, C3H and CBah (a hairless strain). Propane sultone was shown to be carcinogenic when given as a single application of a 25% w/v solution in toluene and also following twice weekly application of a 2.5% w/v solution for up to 58 weeks. More limited exposure to 2.5% w/v solutions of propane sultone resulted in a few skin tumours, although the incidences were not statistically significant. Most neoplasms were papillomas or carcinomas, although a small number of mesenchymal tumours of dermal origin also developed. No skin neoplasms were found in any control mice. The skin application of propane sultone was associated with a statistically significant increase in the incidence of systematic neoplasia in CFl and C3H mice. The exposed CFl mice had a higher incidence of neoplasms of lymphoreticular and lung origin, while female C3H mice showed a higher incidence of mammary gland and uterine tumours. In mice exposed to beta-propiolactone as a positive control, neoplasms developed at the site of application but, there was no evidence of increased systemic neoplasis in contrast to the findings with ptopane sultone.

Animals↗
PubMedDate not supplied

Assessment in rats of the reproductive toxicity of gasoline from a gasoline vapor recovery unit.

Gasoline (CAS 86290-81-5) is one of the world's largest volume commercial products. Although numerous toxicology studies have been conducted, the potential for reproductive toxicity has not been directly assessed. Accordingly, a two-generation reproductive toxicity study in rats was conducted to provide base data for hazard assessment and risk characterization. The test material, vapor recovery unit gasoline (68514-15-8), is the volatile fraction of formulated gasoline and the material with which humans are most likely to come in contact. The study was of standard design. Exposures were by inhalation at target concentrations of 5000, 10 000, and 20 000 mg/m(3). The highest exposure concentration was approximately 50% of the lower explosive limit and several orders of magnitude above anticipated exposure during refueling. There were no treatment-related clinical or systemic effects in the parental animals, and no microscopic changes other than hyaline droplet nephropathy in the kidneys of the male rats. None of the reproductive parameters were affected, and there were no deleterious effects on offspring survival and growth. The potential for endocrine modulation was also assessed by analysis of sperm count and quality as well as time to onset of developmental landmarks. No toxicologically important differences were found. Therefore, the NOAEL for reproductive toxicity in this study was > or =20 000 mg/m(3). The only systemic effects, in the kidneys of the male rats, were consistent with an alpha-2 u-globulin-mediated process. This is a male rat-specific effect and not relevant to human health risk assessment.

Administration, Inhalation↗
PubMedDate not supplied

Ninety-day feeding study in Fischer-344 rats of highly refined petroleum-derived food-grade white oils and waxes.

Subchronic 90-day feeding studies were conducted in male and female Fischer-344 (F-344) rats on highly refined white mineral oils and waxes representative of those used for food applications. The goal was to help clarify the mixed results found in other toxicity studies with laboratory animals. Seven white oils and 5 waxes were fed at dietary doses of 20,000, 2,000, 200, and 20 ppm and compared with control groups on untreated diet; toxicity was assessed at 90 days and also after a reversal period of 28 days and/or 85 days. Higher molecular-sized hydrocarbons (microcrystalline waxes and the higher viscosity oils) were without biological effects. Paraffin waxes and low- to midviscosity oils produced biological effects that were inversely related to molecular weight, viscosity, and melting point; oil type and processing did not appear to be determinants. Biological effects were more pronounced in females than in males. Effects occurred mainly in the liver and mesenteric lymph nodes and included increased organ weights, microscopic inflammatory changes, and evidence for the presence of saturated mineral hydrocarbons in affected tissues. Inflammation of the cardiac mitral valve was also observed at high doses in rats treated with paraffin waxes. Further studies are required to elucidate the mechanism for the responses observed and the relevance of these inflammatory responses in the F-344 rat to other species, including humans.

Animals↗