Showing papers by "Mark Wilkinson published in 1991"

Comparison of the diagnostic yields of disposable and reusable cytology brushes in fibreoptic bronchoscopy.

Abstract: Disposable rake and reusable bristle type cytology brushes have been compared in 50 patients undergoing fibreoptic bronchoscopy for suspected malignancy. Forty seven patients were eventually found to have carcinoma of the bronchus. A diagnosis of malignancy was made from the specimens taken with one or other brush in 34 patients, from the reusable brush in 28, and from the disposable brush in 31. The specimens taken with the two types of brush were of similar quality. The reusable brush is about five times less expensive per procedure but carries a risk of cross contamination and cross infection, and time is needed to clean the brush after each bronchoscopy. The diagnostic yield appears to be at least as good with the disposable brush.

The use of primitive character state distributions in the assessment of holophyly

Abstract: Cladistic analyses are based on the distinction between primitive and derived character states (hypotheses of the polarity of evolutionary transformations) and a complete reliance on only derived character state distributions as bona fide evidence of holophyletic assemblages of taxa. The cladistic premise that only derived character state distributions provide evidence of holophyly is reconsidered and shown to be both unjustified and inconsistent with the desire or methodological prescription of using all the available evidence. Cladistic techniques are here viewed primarily as methods for the ordering of character states so that they may be differentially weighted. The problem of assigning realistic differential weight to primitive and derived character state distributions is briefly discussed. One possible use of primitive character state distributions as evidence of holophyly that is largely free of the problem of weight is proposed. This application is illustrated with an example from the caecilian amphibians (Amphibia: Gymnophiona).

Development of cor pulmonale in tight-skin mice with genetic emphysema.

Abstract: In man, one of the worst prognostic features in emphysema is the development of pulmonary hypertension and right ventricular hypertrophy (RVH). The investigation of RVH in emphysema is made difficult by the inadequacy of the available animal models. It was therefore of interest to investigate the development of RVH in the tight-skin mouse, a new model of genetic emphysema.’ In these mice, emphysema first occurs at 3-4 weeks of life and progresses thereafter.* Male tight-skin (C57 BL/6J-tsk+ / + p a ) mice and female pallid (C57 BL/6J p a + l + p a ) mice were obtained from Jackson Laboratory (Bar Harbor, Maine) and allowed to mate. The colony was maintained, whenever possible, by sibling mating, using t s k + l + p a males and homozygous p a + / + p a females. In all studies the pallid p a + l + p a mice served as controls for the t sk+l+pa mice. Male and female p a and tsk mice 2, 4, 8, 16, and 24 months old were used in this study. At all ages body weight of tsk mice was lighter than that of p a mice. This was significant at 8 ( l l%) , 16 (-21%), and 24 (-22%) months.) In tsk mice right ventricular (RV) weight was significantly lighter at 2 months, held similar values as in the pa mice at 4 and 8 months, and was heavier at 16 (+9%, ns) and 24 (+ 52%, p <0.001) month^.^ In the mouse, as in a wide range of mammalian species, heart mass is directly proportional to adult body m a s 4 Thus, it would be expected that the RV mass of the tsk mice from the eighth month of age onward should have been significantly lighter than that of the pa mice. As this was not the case, it could mean that in the tsk mice RVH first started to develop between 8 and 16 months of age.