Biomedical subjects
Publications and source records attributed to J I Wells.
The factors involved when sampling powder mixes have been reviewed. The various methods are evaluated (manual, automatic, and sub-sampling) and the errors incurred are discussed. Certain rules have been applied to various samplers and their suitability for powder mixtures are described. The spinning riffler is apparently the most suitable, while the use of sample thieves should be avoided due to error and bias.
The factors affecting powder mixing are reviewed. Methods of analyzing a random mix are discussed (indices, the Poisson distribution, and analyses of variance [ANOVA]). The influence of particle size, shape, and density are described, along with scale of scrutiny and sampling. Segregation and agglomeration are major problems in powder mixing, and their prevention and minimization are therefore paramount. Ordered mixing reduces segregation, but also introduces other problems. Regulating the particle size of the drug and altering particle shape minimizes segregation and agglomeration.
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The diagnostic importance of a cytological evaluation of a Gram-stained smear of the discharge from a case of non-purulent vaginitis (NVP) due to corynebacterium vaginale is emphasized. A battery of rapid laboratory tests designed to identify the organism on the second day of incubation with an accuracy of at least 97% is proposed. In a prospective study of 1402 patients, 310 (22%) were found to be asymptomatic carriers of C. vaginale and 42 (3%) had vaginal discharge attributable only to C. vaginale. The clinical features of NVP and results of several treatment regimens in a controlled trial of treatment are compared. Metronidazole given by mouth (1200 mg/day in divided doses) produced the best remission rate, although complicating candidiasis developed in 25% of cases.
A simple set of tests is proposed to give excellent probability for the identification of Corynebacterium vaginale from clinical material. Using these tests, 380 C vaginale were isolated from genital tract specimens from 1402 patients. Of these isolates 70 were from symptomatic patients. These 70 isolates were subjected to a further set of tests to confirm their identity. The advantage of these primary tests is that they can be completed on the day of isolation of the organism. Of these 70 isolates 66 were confirmed as C vaginale thus giving the primary set of tests a 94% rate of accurate identification. However this rate may be increased beyond 97% by the promotion of one of the key secondary tests to the primary set.
The surface areas generated by the disintegration and dissolution of six commercial brands of phenylbutazone tablets B.P. 100 mg have been measured using a Model TA Coulter Counter. The graphs of surface area generated against time were all of the same shape and always reached a maximum value. The initial surface area increase was due to tablet disintegration and deaggregation and followed first order kinetics. A good correlation between the slope of this initial increase and disintegration time was found. The maximum surface area generated correlated at the probability level of better than 99-9% with the dissolution rat measured as t60. The subsequent decrease in surface area, after this maximum, was considered to be due to phenylbutazone dissolution and was also first order rate controlled.
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Of 1947 Aboriginal women who resided in non-metropolitan regions of Western Australia and gave birth during January 1983 to February 1985, 42% of women were screened prenatally for the presence of hepatitis B surface antigen (HBsAg). The proportions of Aboriginal women who were screened varied from 17% in the southern divisions to 72% in the Kimberley region. The screening programme identified 29 Aboriginal women with a positive result of the test. On this basis, the estimated prevalence of HBsAg among non-metropolitan Aboriginal women was 3.6% (95% confidence interval, 2.5%-5.1%). According to the geographical location of the mother's residence, the observed prevalence of HBsAg varied from 0 in the southern divisions to around 4%-5% in the central and eastern divisions.