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Biomedical subjects

C D Roberts

Publications and source records attributed to C D Roberts.

At least 19 recordsLinked to original sources
PubMed1991

Statistical model in tests for eye irritants.

A test used to classify substances for eye irritancy, as required by the Consumer Product Safety Commission, is performed on 1-3 groups of 6 albino rabbits in a sequential manner. When the statistical implications of the test are realized, it is possible for a substance to be classified as an irritant with fewer reactions than the number required for it to be classified as not an irritant. A procedure is given for correcting the inconsistency in the current test, and an alternative test, which considerably reduces the number of animals required, is proposed. Probability models and expected sample size calculations have been derived.

Animal Testing Alternatives↗
PubMed1979

Bacteriological quality control in human milk-banking.

The bacteriological quality of pooled human milk donated to the Oxford milk bank was analysed and the effects on bacteriology of sterilisation of the milk-collecting vessels in the home with hypochlorite solution and of Holder pasteurisation in a purpose-built human-milk pasteuriser were studied. Collecting milk in hypochlorite-sterilised vessels resulted in a significantly lower bacterial count of both pathogens and species of unlikely pathogenicity before pasteurisation and significantly increased the chance of pasteurisation giving a sterile product. Potentially pathogenic organisms grown in untreated milk were Escherichia coli, Staphylococcus aureus, and group B beta-haemolytic streptococci. Seven species of organisms of unlikely pathogenicity were also identified. Pasteurisation eliminated all potential pathogens from milk but did not reliably remove any of the species of unlikely pathogens. Banked human milk may be contaminated with bacteria which are known to be capable of producing lipases, proteases, and decarboxylases. Accurate pasteurisation, together with attention to the sterility of the collecting vessels, results in a bacteriologically safe product that retains many of the protective properties of raw milk.

Disinfection↗
PubMed1977

Acne vulgaris: an investigation into the number of anaerobic diphtheroids and members of the Micrococcaceae in normal and acne skin.

A quantitative study was made of the microflora of 174 acne and 68 non-acne subjects. Two groups of organisms were investigated, the anaerobic diphtheroids and members of the Micrococcaceae. The results showed high numbers of both groups of bacteria in skin bearing blackheads, papules or pustules and in non-acne adolescent skin. There were significantly lower numbers of bacteria in the pilosebaceous ducts of normal looking skin in acne areas and in pre-adolescent skin when compared with non-acne adolescent skin. It is suggested that increased numbers of bacteria alone do not predispose to acne, but that their interaction with the skin, which is a function of the localized skin environment, may be important.

Acne Vulgaris↗
PubMed1975

An explanation fro chloracne -- an industrial hazard.

Patients with chloracne were investigated and the results compared with data matched for age and site from patients with acne vulgaris. The ultrastructural appearances of pilo-sebaceous ducts in both groups were similar. The industrial group had significantly fewer C. acnes than the patients with ordinary acne. They also showed a significant increase in the surface lipid percentage composition of squalene, wax ester and cholesterol and this was associated with a significant decrease in the triglyceride free fatty acids and total triglyceride pool. We suggest that the acnegenic agent has produced its effect by modifying the metabolism of the pilo-sebaceous fluid.

Acne Vulgaris↗
PubMed1973

Tetracycline and acne vulgaris: a clinical and laboratory investigation.

A satisfactory clinical response to long-term oral tetracycline treatment was associated with a mean serum tetracycline of 1.98 mug/ml. The surface lipid showed an increased triglyceride, decreased free fatty acids, and decreased cholesterol, and the amount of keratin within the pilosebaceous duct was reduced. At this dose level there was no quantitative decrease in the bacterial flora though there was a decrease in the fatty acids. We believe that the latter was due to a direct inhibition by tetracycline on extracellular lipases.

Acne Vulgaris↗