Malignant mesothelioma in Pilbara Aborigines

Malignant mesothelioma occurred in a female Aborigine after environmental exposure to asbestos. All known cases of the disease in Aborigines in Western Australia were reviewed; all occurred in Pilbara residents. Most were exposed while involved in the transport of asbestos from the Wittenoom crocidolite operation. Based on recent estimates of the size of the Aboriginal population in the Pilbara region, their incidence of this disease (250 per million for ages 15 and over) is one of the highest population-based rates recorded.     

Effects of light and temperature on macrocyst formation in paired mating types of Dictyostelium discoideum

Light-dark and temperature shifts performed on myxamoebal populations of mixed mating types indicate that there is early differentiation of the population leading to the macrocyst formation in Dictyostelium discoideum.     

Bile acid metabolism and plasma protein turnover in Crohn's disease

Postprandial duodenal bile acids, intestinal protein loss, and albumin and IgG turnover were studied in 19 non-operated patients with Crohn's disease. A lesion of the terminal ileum was present in 18 of 19 patients, either alone or associated with regional colitis. Identical bile acid studies were made in a control group of 20 patients with chronic diarrhoea of undetermined origin. Duodenal bile acid concentration was decreased in 9 of 19 patients with Crohn's disease, and in 5 of 20 patients with unexplained diarrhoea. The glycine/taurine-ratio was increased in 8 of 17 patients with Crohn's disease, but in only one of the 20 control patients. Abnormal intestinal protein loss was present in 13 of 14 patients with Crohn's disease. The fractional catabolic rate of albumin and IgG was increased in all 17 cases of Crohn's disease studied, except the patient with no protein loss. A statistically significant and positive correlation was observed between glycine/taurine-ratio and fractional catabolic rate of both albumin and IgG. No patient with Crohn's disease harboured an abnormal bacterial flora in the proximal small intestine. It is concluded that, in the absence of abnormal bacterial flora in the proximal jejunum, the glycine/taurine-ratio is more valuable as an indicator of terminal ileopathy than postprandial duodenal bile acid concentration in nonoperated patients with terminal ileitis. Abnormal intestinal protein loss and increased catabolic rate of albumin and IgG are practically always present in active Crohn's disease and are strong evidence of an organic gastrointestinal lesion in patients with normal radiographic findings.     

Effects of central administration of arginine-vasopressin on aversive memory retrieval

This study examined whether arginine-vasopressin (A-VP), given before the test would produce an improved retrieval of aversive memory, in the same way as pre-exposure to inescapable footshocks, in rats. For this purpose animals conditioned in a T-maze with appetitive (10% sucrose) and aversive (2.0 mA footshock) events were administered (intracerebroventricular) a single dose of 2.5, 5, 10 or 20 ng/rat of A-VP, 20-min before testing. In the retention test conducted with the same training apparatus 72 h after conditioning, the peptide treated rats showed a dose-dependent increase in latencies to enter the previously shocked goalarm, with the absence of such a difference in responding to the non-shocked goalarm. This differential response was not observed in saline treated rats. This effect of peptide on memory retrieval was similar to that seen following inescapable footshock in rats. These results suggest the possible involvement of central vasopressinergic mechanisms in the differential enhancement of memory of helplessness condition.     

On the existence of polyadenylated histone mRNA in Xenopus laevis oocytes

In a variety of systems, histone mRNA has been shown to lack poly(A) (Adesnik and Darnell, 1972; Grunstein et al., 1973). We have found, however, that in Xenopus laevis oocytes, poly (A)-containing mRNA codes for histones, in a wheat germ cell-free system, based on the following criteria: first, co-migration with authentic X. laevis oocyte histones on polyacrylamide gels; second, no detectable incorporation of tryptophan; third, differential incorporation of lysine and methionine into histone fraction H2A; fourth, resistance of histone fraction H2A to cleavage with cyanogen bromide; and fifth, correspondence of tryptic peptide maps of partially purified cell-free products with authentic X. laevis oocyte histone. RNA which directs the synthesis of histones in the cell-free system is retained on oligo(dT)-cellulose, even after denaturation in 80% DMSO at 70 degrees C, thereby demonstrating the covalent attachment of polyadenylic acid sequences to the mRNA. Poly (A)- RNA (7S-14S fraction) was also found to code for histones using the same criteria. We discuss the significance of the finding that X. laevis oocytes contain two classes of histone mRNA as well as the potential developmental implications of this observation.     

Validation and adjustment of the mathematical prediction model for human sweat rate responses to outdoor environmental conditions

Under outdoor conditions this model was over estimating sweat loss response in shaded (low solar radiation) environments, and underestimating the response when solar radiation was high (open field areas). The present study was conducted in order to adjust the model to be applicable under outdoor environmental conditions. Four groups of fit acclimated subjects participated in the study. They were exposed to three climatic conditions (30 degrees, 65% rh; 31 degrees C, 40% rh; and 40 degrees C, 20% rh) and three levels of metabolic rate (100, 300 and 450 W) in shaded and sunny areas while wearing shorts, cotton fatigues (BDUs) or protective garments. The original predictive equation for sweat loss was adjusted for the outdoor conditions by evaluating separately the radiative heat exchange, short-wave absorption in the body and long-wave emission from the body to the atmosphere and integrating them in the required evaporation component (Ereq) of the model, as follows: Hr = 1.5SL0.6/I(T) (watt) H1 = 0.047Me.th/I(T) (watt), where SL is solar radiation (W.m-2), Me.th is the Stephan Boltzman constant, and I(T) is the effective clothing insulation coefficient. This adjustment revealed a high correlation between the measured and expected values of sweat loss (r = 0.99, p < 0.0001).     

A generalized F mixture model for cure rate estimation

Cure rate estimation is an important issue in clinical trials for diseases such as lymphoma and breast cancer and mixture models are the main statistical methods. In the last decade, mixture models under different distributions, such as exponential, Weibull, log-normal and Gompertz, have been discussed and used. However, these models involve stronger distributional assumptions than is desirable and inferences may not be robust to departures from these assumptions. In this paper, a mixture model is proposed using the generalized F distribution family. Although this family is seldom used because of computational difficulties, it has the advantage of being very flexible and including many commonly used distributions as special cases. The generalised F mixture model can relax the usual stronger distributional assumptions and allow the analyst to uncover structure in the data that might otherwise have been missed. This is illustrated by fitting the model to data from large-scale clinical trials with long follow-up of lymphoma patients. Computational problems with the model and model selection methods are discussed. Comparison of maximum likelihood estimates with those obtained from mixture models under other distributions are included.