An objective test of stochastic behavior in riverine water quality models.

Predictions of river water quality models are subject to substantial uncertainties, which depend not only on parameterization and calibration strategies but also on the structure of the conceptual model itself. To evaluate the importance of this effect and associated implications for stochastic models, investigations were conducted based on a segment of the Potomac River in the eastern USA. Two commonly used conceptual representations of real-world processes were used, and their simulation of DO, BOD and NH(4) components scrutinized. A GLUE approach to the inverse problem was then used to examine how uncertainty changed along the river network for each conceptual model. Differences were observed not only between deterministic instances of each conceptual model, but also between their response surfaces as a whole. Uncertainties within the river network are substantially influenced by the selection of calibration data used, as well as the primary source of the constituent examined. The suggested methodology can be used to test conceptual model validity for specific applications. The results of this study will help users select and assess models for varied problems, and refine appropriate data collection and monitoring schemes.

Changes in skeletal muscle in males and females following endurance training.

Gender differences in substrate selection have been reported during endurance exercise. To date, no studies have looked at muscle enzyme adaptations following endurance exercise training in both genders. We investigated the effect of a 7-week endurance exercise training program on the activity of beta-oxidation, tricarboxylic acid cycle and electron transport chain enzymes, and fiber type distribution in males and females. Training resulted in an increase in VO2peak, for both males and females of 17% and 22%, respectively (P < 0.001). The following muscle enzyme activities increased similarly in both genders: 3-beta-hydroxyacyl CoA dehydrogenase (38%), citrate synthase (41%), succinate-cytochrome c oxidoreductase (41%), and cytochrome c oxidase (COX; 26%). The increase in COX activity was correlated (R2 = 0.52, P < 0.05) with the increase in VO2peak/fat free mass. Fiber area, size, and % area were not affected by training for either gender, however, males had larger Type II fibers (P < 0.05) and females had a greater Type I fiber % area (P < 0.05). Endurance training resulted in similar increases in skeletal muscle oxidative potential for both males and females. Training did not affect fiber type distribution or size in either gender.

Human acylation stimulating protein enhances triacylglycerol biosynthesis in plant microsomes.

Diacylglycerol acyltransferase has a universal role in catalyzing the acyl-CoA-dependent formation of triacylglycerol in microorganisms, animals and plants. Acylation stimulating protein, from human blood, is known to enhance diacylglycerol acyltransferase activity and triacylglycerol biosynthesis in human adipocytes. In the current study, acylation stimulating protein was also shown to enhance diacylglycerol acyltransferase activity in microsomes from cell suspension cultures of oilseed rape. Enzyme stimulation occurred over the pH range of 6-9 but the degree of stimulation decreased with increasing ionic strength at pH 7.4. Varying acyl-CoA concentration did not affect the degree of stimulation. Membranes from triacylglycerol producing cells in plants and humans may have similar binding sites for acylation stimulating protein which have been preserved during molecular evolution. The results suggest that human acylation stimulating protein may be useful in modifying lipid biosynthesis in plants.

Urinary tract infection and patient satisfaction after flexible cystoscopy and urodynamic evaluation.

OBJECTIVES: To investigate the incidence of symptomatic and asymptomatic bacteriuria and to assess patient satisfaction after flexible cystoscopy (FC) and urodynamic (UD) evaluation in a prospective survey. The incidence of urinary tract infection after FC and UD studies and the use of prophylactic antibiotics are issues of debate. The tolerability and acceptance of FC and UD studies by patients have not been thoroughly documented. It would be helpful to be able to give such information to patients before performing these procedures. METHODS: A total of 215 nonconsecutive patients seen as outpatients for FC and UD studies to evaluate various indications were studied. A midstream urine sample was taken before and 48 hours after the procedures. Patients were given a questionnaire that inquired about the presence of lower urinary tract symptoms before and 48 hours after the procedures. The self-administered questionnaire included questions to assess patients' tolerance of the procedures and how it compared with their expectations. RESULTS: Of the 201 patients analyzed (FC 103, UD studies 98), 9 patients (4. 5%) developed significant bacteriuria within 48 hours of FC and UD studies. Only 2 patients with significant bacteriuria reported newly developed symptoms within 48 hours. In a subgroup of 25 patients who were given prophylactic antibiotics for various reasons, 6 (24%) reported new symptoms, although none developed significant bacteriuria. The association between patients who had preprocedure pyuria (n = 7) and the development of significant growth after the procedure (n = 6) was significant (P <0.01). In response to the patient-satisfaction questionnaire, 166 (82.5%) reported that the procedure was not as bad as they expected, and 200 (99.5%) said that they would undergo the test again if necessary. CONCLUSIONS: FC and UD studies are safe, well-tolerated procedures. The addition of prophylactic antibiotics in these procedures is unnecessary, unless specific indications are present.

Sarcoma of the prostate treated with radiotherapy.

Sarcoma of the prostate is a rare primary tumour in adults. We report a 73-year-old man who presented with urinary outflow obstruction. He had histologically proven prostatic sarcoma and probably derived some benefit from radiotherapy. A brief review of the literature is included.

Hyponatraemia during transurethral resection--its practical prevention.

Haemodilutional consequences of transurethral resection of the prostate (TURP) can present clinical problems during or in the immediate period following this procedure. Recognition of large and rapid changes in the plasma sodium by inference from an ion selective electrode may avert the development of this potentially life-threatening complication.

The effect of histamine and histamine antagonists on gastric acid secretion and mucosal blood flow in man.

Histamine has been investigated for its effect on gastric acid secretion and mucosal blood flow in man. Dose-response curves were constructed and analysed in the presence of H1- and H2-antagonists. Mepyramine had no effect on acid secretion or mucosal blood flow. Cimetidine reduced acid secretion but had no effect on blood flow. This suggests that the vasculature is less sensitive to cimetidine than the parietal cell.