Biomedical subjects
Publications and source records attributed to A Whitehead.
The direct administration of either 103 or 108 cells of Salmonella enteritidis phage type 4 on to the conjunctiva of laying hens resulted in systemic infection. The bacterium was isolated from a variety of tissues, including the ovary and oviduct, and it was excreted in faeces for at least 27 days after infection.
Hens were exposed to small-particle aerosols containing different concentrations of Salmonella enteritidis phage type 4. They developed a systemic infection and some birds were still excreting the organism in the faeces when killed 28 days after infection. S enteritidis was present for a similar period in a wide range of alimentary tract issues and in the ovary and oviduct.
The fixed-dose procedure (FDP) was proposed by the British Toxicology Society in 1984 as an alternative to the LD50 study in the assessment of the acute oral toxicity of a substance. This paper presents a statistical evaluation of this procedure. A mathematical description of the FDP shows that the starting dose can affect the toxic classification of a substance. The toxic classification based on the FDP is compared with that based on an LD50 test. This shows that, in general, the FDP is likely to result in the same classification or a less toxic one than the LD50 procedure. However, for substances with very shallow dose-response slopes, the FDP is likely to result in the same classification or a more toxic one. The expected number of animals that will be tested and will die using the FDP will be reduced compared with the LD50 study. The results from the international validation study carried out in 1989 showed agreement with the results predicted from the mathematical model.
1. When the contents of 4 or more naturally-contaminated intact eggs were combined, the isolation rate of Salmonella enteritidis was improved by extending incubation at 37 degrees C from 24 to 48 h before sub-culture. 2. The isolation rate of salmonellas from raw homogenised whole egg was significantly increased by the inclusion of Novobiocin and Cefsulodin in the primary culture media. 3. Rappaport Vassiliadis broth was found to be superior to Selenite as a selective enrichment medium.
1. A scheme for augmented spontaneous reporting of adverse drug events using advanced view data systems was developed and applied to study 67,698 consecutive patients prescribed captopril in general practice for the treatment of hypertension. 2. Captopril was an effective hypotensive agent in this population, as only 1.9% of patients were withdrawn because of apparent inefficacy. 3. Adverse effects of captopril resulted in withdrawal of treatment in 8.9% of recipients, and such effects were more frequent in elderly and female recipients. 4. Skin reactions--usually maculopapular rashes--tended to occur early during therapy whereas cough occurred much later and was reported more frequently in non-smokers. 5. Some 1.1% of recipients died during follow-up. There was no evidence of any unusual or unexpected causes of death which might be partially or totally captopril-related in the study cohort. 6. The study confirms the feasibility of large scale postmarketing surveillance studied in general practice and allowed risk benefit assessments to be made on the use of captopril for treating hypertension.
The period during which specific pathogen free hens, infected by direct introduction into the crop of either 10(3), 10(6) or 10(8) cells of Salmonella enteritidis PT4, excreted the organism in faeces was closely related to the size of the inoculum, with the birds excreting for mean periods of 3.4, 16.4 and 36.8 days, respectively. The production of either IgG or IgM was also dose related with the birds which received 10(3) cells having lower antibody levels than those in the other two groups. In contrast, there was no relationship between the contamination of egg contents and either antibody status, faecal excretion, or the dose administered.
Meta-analysis provides a systematic and quantitative approach to the summary of results from randomized studies. Whilst many authors have published actual meta-analyses concerning specific therapeutic questions, less has been published about comprehensive methodology. This article presents a general parametric approach, which utilizes efficient score statistics and Fisher's information, and relates this to different methods suggested by previous authors. Normally distributed, binary, ordinal and survival data are considered. Both the fixed effects and random effects model for treatments are described.
Over 5700 hens eggs from 15 flocks naturally infected with Salmonella enteritidis were examined individually for the presence of the organism in either egg contents or on shells. Thirty-two eggs (0.6%) were positive in the contents. In the majority, levels of contamination were low. Three eggs, however, were found to contain many thousands of cells. In eggs where it was possible to identify the site of contamination, the albumen was more frequently positive than the yolk. Storage at room temperature had no significant effect on the prevalence of salmonella-positive eggs but those held for more than 21 days were more likely (P less than 0.01) to be heavily contaminated. In batches of eggs where both shells and contents were examined, 1.1% were positive on the former site and 0.9% in the latter.
In a double-blind comparison of haloperidol decanoate and fluphenazine decanoate given 4-weekly for 60 weeks as maintenance therapy in 38 chronic schizophrenic in-patients, plasma haloperidol, fluphenazine and prolactin levels were measured at regular intervals by radioimmunoassay. After the first injection, the mean plasma haloperidol level was highest at week 1 and fell gradually towards week 4. Mean pre-dose haloperidol levels changed little after week 8. Results suggested an absorption half-life of 4 weeks, although, in three cases steady state was only achieved after 11 monthly injections. Steady state levels of both haloperidol and fluphenazine correlated highly with dose. In two sub-groups observed at steady state, both drugs produced a biphasic pattern of plasma drug concentration between injections, a rapid rise on day 1 followed by stable elevated levels and a gradual return to pre-injection concentration by the end of week 4. In the fluphenazine sub-group there was a second peak on day 7 and a steeper decline, so that the mean area-under-curve in week 4 was 64% of that in week 1. Drug injections at steady state induced an increase in prolactin secretion in all of the fluphenazine sub-group and in half of those receiving haloperidol. Plasma prolactin changes resembled those for drug concentrations, but differences in times of peaks on day 1 resulted in weak correlations. Fluphenazine appeared more potent than haloperidol in provoking prolactin secretion.
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The total weight of the normal adult human heart as well as that of each ventricle is proportional to body size. Body weight is superior to height as a predictor of total heart and isolated ventricular weights. Ventricular wall thickness is an insensitive means of assessing ventricular hypertrophy. Heart weight is a poor predictor of isolated right ventricular mass but a slightly better predictor of isolated left ventricular mass. The only method of determining the presence or absence of hypertrophy with confidence is to use the Fulton technique for isolated ventricular weights. The use of an arbitrary upper and lower limit, as currently used, for isolated ventricular weights obtained by Fulton's method may, however lead to errors in determining the presence or absence of ventricular hypertrophy.
Preliminary results of a study of the possible relationship of depot-medroxy-progesterone acetate (DMPA) to invasive cervical cancer are presented. The findings are based on data from three participating centres in Thailand and one in Mexico. A relative risk for cervical cancer of 1.2 was observed in women who had ever used DMPA; this was not statistically significant. No consistent increase in risk with duration of use was observed, although a relative risk of 2 was found in women who had used DMPA for more than 5 years. This observed increase in risk was confined to women who were aged under 46 years or who had first been exposed to DMPA before 30 years of age. These findings are based on small numbers of subjects, and may not represent a causal relationship.
The preliminary results of a study of the incidence of breast cancer in relation to use of depot-medroxyprogesterone acetate (DMPA) are presented. The findings are based on data from three participating centres in Thailand, and one each in Kenya and Mexico. A relative risk for breast cancer of 0.7 was observed in women who had ever used DMPA; this was not statistically significant. Although no consistent decrease in risk with duration of use was observed, the lowest relative risk (0.5) was observed in women who had used DMPA for three or more years. These findings are based on small numbers and must be considered preliminary. However, they provide no evidence that DMPA increases the risk of breast cancer, and suggest that it may exert a protective effect, particularly in long-term users.
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Explore the source record for details and available documents.
Attitudes towards 'self' and 'partner' were studied in couples undergoing three different behavioural treatments for sexual inadequacy: systematic desensitization with counselling; guided practice with counselling; and practice with minimal counselling. Factor analysis of semantic differential scales identified five components--general evaluation, anxiety, and three factors relevant to sexual evaluation designated as 'loving', 'sexually attractive' and 'easy to arouse'. Differences in derived factor scores were found which related to sex of rater, identity of complainant, and treatment received; with the treatment combining guided practice with counselling being followed by significantly greater attitude changes.