Biomedical subjects
Publications and source records attributed to D Griffiths.
Testicular tumors of a similar histological type have been reported rarely in families. We report on 2 nontwin brothers and a first cousin who presented with embryonal carcinoma.
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86 renal allograft recipients were randomly assigned to cyclosporin (Cy) for 90 days followed by azathioprine and prednisolone (Aza and P), or to Aza and P from day 0, as part of the second Oxford trial of short-term Cy use. All 62 patients whose grafts functioned for at least 120 days were included in this study. Serum creatinine was significantly higher in Cy-treated patients than in control patients from day 28 to day 90. Serum uric acid was also significantly higher in Cy-treated patients over the same period. Both creatinine and uric acid fell to the level of the control group after conversion to Aza and P. Serum uric acid was significantly higher for a given level of creatinine during Cy treatment than in either the control patients or the Cy-treated patients after their treatment had been changed to Aza and P. These data imply that Cy affects both the glomerular filtration rate and renal tubular function but that these effects are largely reversible.
A definition is proposed for tube pressure (the pressure within a collapsible tube in the collapsed state, e.g. the urethral pressure or the pressure in the anal or oesophageal sphincter) which conforms to the common sense view that it is a measure of the ability of the tube to prevent leakage. It is not dependent on the orientation of a measuring probe in the tube. The orientation effects which have previously been reported are due to attempted bending of a stiff measuring catheter by internally and externally applied forces. A satisfactory way of measuring the tube pressure, by slow perfusion through a thin, flexible catheter with an end hole, and of testing whether it is a meaningful concept in a given case, is proposed. It is illustrated by measurements of urethral pressure in 42 continent and incontinent females. No cases of urinary incontinence due to poor urethral sealing ability are observed, indicating that tube pressure is a meaningful concept. The theory of viscosity-limited flow through a compressive zone in a collapsible tube, on which the perfusion method of measuring tube pressure is based, is developed.
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Plasma melatonin concentration of immature male elephant seals was determined by radioimmunoassay. Comparison of concentrations during two 24-h periods, one in midsummer and one in midwinter, showed that there was a marked circadian cycle in winter which was greatly modified during the long day length of summer. It is suggested that in summer there was sufficient ambient lighting during the night hours to depress the nocturnal rise in plasma melatonin. The complexity of pineal cycles in the natural environment is stressed, and in this regard the polar regions are of particular interest due to the extreme seasonal changes in day length there.
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Given an underlying distribution for the number of encounters between parasites and a host this may be generalised by the distribution of the number of eggs per encounter. If eggs are already present, a parasite may avoid oviposition at subsequent encounters. A class of avoidance-modified generalised distributions is presented to model such situations. The case of a solitary (single egg-laying) parasite and a Poisson distribution for the number of encounters gives rise to a distribution of particular interest. Various properties of this distribution are derived and alternative estimation procedures investigated. Estimators based on the method of mean and zero frequency are shown to have the dual advantages over other estimators that have been proposed of simplicity of computation and increased efficiency. Over a wide range of parameter values there is virtually no loss of efficiency in comparison with maximum likelihood estimation.
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