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Biomedical subjects

D O Chanter

Publications and source records attributed to D O Chanter.

10 recordsLinked to original sources
PubMed1994

A study of the association between hormone replacement therapy, smoking and the occurrence of myocardial infarction in women.

The initial results are reported of a case-control study undertaken on the VAMP multi-purpose database and designed to estimate the risk for first-time occurrence of myocardial infarction in users of hormone replacement therapy (HRT). The findings currently available relate to the computerized data and show 2- to 5-fold increases in risk in smokers and those with diabetes mellitus, hypertension or hyperlipidaemia. With any form of HRT, a non-significant protective effect [adjusted odds ratio = 0.83 with 95% CI (confidence intervals) of 0.66-1.03, p = 0.089] has been shown. However, the protective effect of HRT in the data available to date appears to be confined to non-smokers in whom the odds ratio in the absence of other risk factors is 0.70 (95% CI of 0.49-1.00). The comparable odds ratio in smokers is 1.05 (95% CI of 0.71-1.53). These results should be interpreted with caution as smoking status was unknown for about half of the subjects and was more complete among the cases than controls.

Case-Control Studies↗
PubMed1987

The chances of false negative results in conventional toxicology studies with rats.

Data from conventional rat toxicology studies from 2 centres are used to estimate the coefficients of variation of organ weights, haematology and blood chemistry characteristics commonly measured in such studies. Charts, based on simple statistical formulae, are provided which enable this information to be used to indicate the probability of failing to detect a treatment effect of a given magnitude as statistically significant. The results, for a study with 20 rats/treatment group, when the treatment causes a change of 10% in the characteristic, indicate wide variability in the false negative error rate. With some characteristics (e.g. haemoglobin, total protein, brain weight, red blood cell count) the false negative rate is less than 0.1%, but for others (e.g. white blood cell count, glutamic-pyruvic transaminase, pituitary weight, cholesterol) it is in excess of 70%.

Animals↗
PubMed1985

The determination of mean residence time using statistical moments: is it correct?

The estimation of mean residence time using statistical moment theory is shown to lead to the true mean residence time only in the case of a concentration-time curve which is a single exponential. In other cases, including the commonly encountered double exponential, there is a systematic error present which can lead to the result being incorrect by as much as a factor of 2. For the case of instantaneous input, an alternative estimation procedure is suggested which gives an estimate much closer to the true mean residence time.

Models, Biological↗
PubMed1985

Effect of avoparcin interaction with anticoccidial compounds on the growth and carcase composition of broilers.

The anticoccidial drugs narasin, lasalocid, monensin and salinomycin, with and without avoparcin, were fed to 1280 broiler chickens from 1 to 49 d old. At day 49 significant interactions were detected between avoparcin and the anticoccidial compounds for body weight and food consumption. This indicated that the increases in body weight and food consumption obtained with avoparcin were greater with some anticoccidial compounds (lasalocid and salinomycin for body weights and lasalocid for food consumption) than with others (monensin and narasin for body weights and monensin, narasin and salinomycin for food consumption). Overall there was evidence that avoparcin increased body weight (5.8%), food consumption (2.5%) and efficiency of food utilisation (2.9%). In addition avoparcin produced significant increases in plucked weight and the proportion of visceral fat together with and decreases in the proportions of edible giblets and waste offal.

Animals↗
PubMed1982

The LD50 test: some considerations of precision.

Substantial improvements in the statistical aspects of the LD50 test are possible. These include modifications to the design of the experiments (including the use of sequential methods) and the replacement of outdated techniques of statistical analysis with more appropriate methods. With such improvements, it would be possible to reduce appreciably the number of animals used (to about 10 or 12) while still achieving precision similar to that obtained with present methods.

Animals↗