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Biomedical subjects

G M Raab

Publications and source records attributed to G M Raab.

42 records · Page 3Linked to original sources

Management of post-cricoid carcinoma.

This paper discusses the results of treatment of post-cricoid carcinoma based on a personal series of 141 patients. The following conclusions can be drawn: small tumours with no clinical evidence of cervical lymph node metastasis should almost certainly be treated with radiotherapy, which gives a 5-year survival of approximately 35%. Surgery for recurrent disease after radiotherapy if fraught with complications, and satisfactory salvage is seldom possible. Surgery for larger tumours and those associated with neck node metastases has a lower (20%) 5-year survival with a high incidence of complications. The main problem after pharyngolaryngectomy is replacement of the pharynx. There is no evidence that any one of the methods in common use (skin flaps, transposition of the colon or stomach) is superior to any other.

Adult↗

Variance function estimation for immunoassays.

A computer program is described which implements a recently described [1], modified likelihood method of determining an appropriate weighting function to use when fitting immunoassay dose-response curves. The relationship between the variance of the response and its mean value is assumed to have an exponential form, and the best fit to this model is determined from the within-set variability of many small sets of repeated measurements. The program estimates the parameter of the exponential function with its estimated standard error, and tets the fit of the experimental data to the proposed model. Output options include a list of the actual and fitted standard deviation of the set of responses, a plot of actual and fitted standard deviation against the mean response, and an ordered list of the 10 sets of data with the largests ratios of actual to fitted standard deviation. The program has been designed for a laboratory user without computing or statistical expertise. The test-of-fit has proved valuable for identifying outlying responses, which may be excluded from further analysis by being set to negative values in the input file.

Analysis of Variance↗

The potential of mid-trimester maternal plasma alpha-fetoprotein measurement in predicting infants of low birth weight.

Maternal plasma alpha-fetoprotein (AFP) was measured at mid-trimester in 113 women who subsequently were delivered of a singleton liveborn infant weighing less than 2.5 kg and in 113 matched controls whose infants weighed more than 2.5 kg. Plasma AFP levels were significantly higher in the subjects than in the controls, while 10 of the subjects and only 3 of the controls had values above 2.0 times the median. The higher AFP concentrations were seen both in pregnancies in which the outcome was a small premature infant and in those in which it was a small-for-dates baby.

Female↗

Incorporating HIV test data into forecasts of the AIDS epidemic in Scotland.

For AIDS cases in Scotland the date of HIV antibody positive diagnosis (HIV test date) is recorded on the AIDS case reports. Data are also available on the total numbers of individuals with HIV positive test reports in Scottish laboratories in each year since testing became available. These data are incorporated into a model of the HIV epidemic described in terms of testing rates by calendar year. The HIV infection curve is modelled as a step function, and the testing rates are allowed to differ between steps. Results are presented for intravenous drug users (IDUs) and for homosexual/bisexual men. The estimated rates of testing for the IDUs (estimates from 19 per cent to 44 per cent per year) are considerably higher than those for homosexual/bisexual men (estimates of 10 per cent to 17 per cent per year). Data on the year of testing for AIDS diagnoses gave relatively little improvement in estimates of the HIV infection curve. However, when this information is combined with data on the total number of HIV positive diagnoses per year, there is a dramatic improvement in the estimate of the HIV infection curve. This is particularly marked for infections in the most recent period and for the estimates of cumulative infections up to the present. However, these improvements are gained at the cost of assumptions of similar testing rates applying to all sections of the HIV infected populations, which will be difficult to check in practice. This suggests that these methods should not be used in isolation but in combination with other evidence about the spread of HIV infection in a population.

Acquired Immunodeficiency Syndrome↗