Avascular necrosis of the femoral head in childhood systemic lupus erythematosus

Four of 10 children with SLE kept under observation over the past nine years have developed avascular necrosis (AN) of the femoral head. The symptoms of AN are insidious and unpredictable and predate the radiologic diagnosis by weeks to months. In a comparison of these children with SLE, with and without AN, with a group of patients with nephrosis treated with corticosteroids and a group with glomerulonephritis treated with azathioprine, AN was related to the duration of daily steroid therapy rather than the total duration of steroid treatment; this was not true for azathioprine. The occurrence of AN in our patients while they were on alternate-day steroid therapy, or coincident with a relapse, suggests that its development is determined by underlying disease.     

Automated statistical analysis of microbial enumeration by dilution series

Equations are formulated for the standard error and confidence interval for the MPN estimate of microbial density from a general dilution series. A statistical test of homogeneity is presented. This tests whether a handling error in the dilution series may have occurred which would invalidate the density estimate. The analysis may be automated using a Basic computer program which contains a fast algorithm for the solution of the general MPN equation. This allows the calculation of the MPN, standard error, 95% confidence interval and test statistic for any dilution series, with any degree of replication at each dilution level, with variable sample volumes at each dilution level, with variable dilution ratio between levels, and with any number of levels.     

The survival of skeletal muscle myoblasts in vitro is sensitive to a donor of nitric oxide and superoxide, SIN-1, but not to nitric oxide or peroxynitrite alone.

The survival of skeletal muscle myoblasts in culture after exposure either to a donor of NO, sodium nitroprusside (SNP), or ethanamine, 2,2'-(hydroxynitrosohydrazono)bis-(DETA NONOate), or to a donor of both NO and O(-)(2), 3-morpholinosydnonimine hydrochloride (SIN-1), was investigated. SIN-1 reduced clonogenic survival markedly but donors of NO alone did not. The injurious effect of SIN-1 was prevented by oxyhemoglobin or by uric acid but not by superoxide dismutase. The exposure of myoblasts to authentic peroxynitrite (ONOO(-)) or to DETA NONOate in the presence of an O(-)(2)-generating system did not reduce their survival. The results show that NO or ONOO(-) alone is not detrimental to myoblast survival and suggest that SIN-1 toxicity is, at least in part, mediated by H(2)O(2) in this myoblast culture system.     

An individual-based model for predicting the emergence period of sea trout fry in a Lake District stream

The objective of this study was to predict interannual fluctuations in the emergence period of sea trout fry, using models developed from field data for 70 excavated redds, and laboratory data on egg and alevin development at 30 constant temperatures (range 1·5–10·5° C with 100 naturally fertilized eggs at each temperature). Egg weight and numbers per redd both increased with female length; a power function described the relationship. Early spawners were the largest females laying the largest and most numerous eggs, whilst late spawners were the smallest females laying the smallest and least numerous eggs; middle spawners being intermediate between these two extremes. Mean values for egg weight and numbers of eggs per redd were obtained for these three groups. Hatching and emergence times in the laboratory decreased with increasing temperature. Of five models tested for hatching time, the best fit was provided by a three-parameter hyperbolic model which formed the asis of the individual-based model used to predict egg hatching and fry emergence. Model development was described in detail and the final equations predicted the times taken for 5, 50 and 95% of the fry to emerge, and hence the period over which 90% of the fry emerged. Analogous models were obtained for egg hatching. All models were excellent fits to the laboratory data. Hatching times for eggs kept in perforated boxes in the stream were almost identical to those kept at similar mean temperatures in the laboratory. Model predictions of fry emergence times were validated by field data for 8 years (1967–1971, 1974, 1975, 1980). The chief objective was therefore fulfilled, and predictions for the 30-year study (1967–1996) revealed a large variation in the timing of emergence (extremes: 11 March–4 April 1989, 15–20 May 1979). Most of the variation in median emergence date was due to variations in water temperature, with spawning dates as a secondary factor; the latter, however, had a greater effect on the length of the emergence period.     

The effects of the perfusion of various solutions on the no-reflow phenomenon in experimental free flaps.

The effects of solution perfusion in the free epigastric flap of the rabbit, after normothermic ischemic periods of 8 hours or 12 hours, have been examined by operative microscopic and histological methods. A smaller group of animals was also studied in which the perfusion was done before the ischemic insult. An ischemia-related obstruction to the peripheral blood flow occurred in the absence of stagnant ischemic blood in this model. Although the 3 perfusion fluids studied were shown to penetrate to all levels of a flap after such an ischemic period, none of them had a beneficial effect on skin survival. However, the solution containing mannitol did have a protective effect on fat survival. Analogies between these experimental findings and the clinical situation are made, and the importance of the early diagnosis and treatment of ischemia in a flap is emphasized.     

Developmental patterns of copper and zinc concentrations in mouse liver and brain: evidence that the gene crinkled (cr) is associated with an abnormality in copper metabolism

An abnormality in copper metabolism during both the prenatal and postnatal (preweaning) periods was found to be associated with the autosomal recessive gene ”crinkled“ (cr) in mice. Liver copper concentration was significantly lower in crinkled mice (cr/cr) than in littermate controls (+/?) from 18 days of gestation to 20 days after birth. Crinkled mice older than 20 days of age had liver copper concentrations similar to those of littermate controls. Liver zinc and brain copper and zinc were similar in crinkled and noncrinkled mice at all times tested. In both crinkled and noncrinkled mice, brain copper concentration increased during the suckling period, and liver copper concentration decreased.