Perceived exertion associated with breathing hyperoxic mixtures during submaximal work

The effect of an enriched inspired oxygen concentration on perceived exertion (RPE) was investigated while running at two submaximal treadmill loads. Twelve males (VO2 max = 49.3 ml/kg-min) worked at 50% and 80% VO2 max, breathing either air or 80% O2-20% N2 in random order using a single blind technique. Subjects were evaluated while running for 10 min and during a 20 min recovery. Heart rate (HR), ventilation (VE), respiration rate (RR), tidal volume (VT) and RPE were measured before, during and after work. Blood lactate was measured 1 min after work. Oxygen concentration did not statistically affect HR, VE, RR or VT during exercise or recovery. At both loads, RPE at the end of exercise was significantly reduced breathing the hyperoxic mixture. At 50% VO2 max, mean RPE decreased from 11.2 breathing room air to 9.6 breathing 80% O2 and, 80% VO2 max, from 13.8 to 11.7 (P less than 0.01). Blood lactates were significantly reduced breathing 80% O2; from 23.4 mg to 13.3 at 50% VO2 max and from 55.5 to 36.5 at 80% VO2 max (P less than 0.01). The RPE correlated with lactate (r=0.64) at the end of work. Results indicate that during moderate and heavy work RPE is significantly affected by the inspired O2 concentration and there is a significant relationship between RPE and blood lactate.     

Effects of phenobarbital and diazepam on imipramine-induced changes in blood pressure, heart rate and rectal temperature of rats

To investigate the safety of anticonvulsants in doses found equipotent in suppressing imipramine induced convulsions, the effects of diazepam (1.8 mg/kg) or phenobarbital (40 mg/kg) following a toxic dose of imipramine (50 mg/kg) on heart rate, blood pressure and body temperature were examined in male Wistar rats. Administration of imipramine alone resulted in significant decreases in blood pressure, heart rate and rectal temperature. Phenobarbital or diazepam alone failed to significantly affect any of these parameters apart from a slight reduction in rectal temperature seen with phenobarbital. Diazepam given after imipramine antagonized the imipramine-induced decrease in heart rate but increased the hypotensive and hypothermic effects. Phenobarbital failed to significantly affect the imipramine-induced changes in any of the physiological parameters studied. The present data suggests that phenobarbital may be preferable to diazepam in treatment of imipramine-induced convulsions.     

Bronchial reactivity: interaction between vagal stimulation and inhaled histamine

The interaction between the effects of vagal stimulation and inhaled histamine on the bronchi was studied in anesthetized dogs. Reactivity was assessed by measuring changes in bronchial caliber visualized with tantalum bronchograms. In seven vagotomized dogs the bronchoconstrictor response to a combination of electrical stimulation of the vagus nerves and inhaled histamine solution produced a mean reduction in airway diameter (Daw) of 2.21 mm which was significantly greater than the additive results of the two stimuli applied separately (mean decrease in Daw 0.29 +/- 0.91 mm). In three dogs the effect of vagal stimulation was to produce a shift in the dose-response curve to inhaled histamine. These results indicate that the effect of the base-line bronchomotor tone must be considered in the evaluation of the effect of vagal blockade on airway reactivity. An increase in the resting degree of bronchomotor tone may contribute to the hyperreactivity observed in patients with asthma.     

The effect of physician-controlled health insurance. U.S. v. Oregon State Medical Society

The trial record in an antitrust case against the Oregon State Medical Society, finally decided in 1952, was examined to reconstruct the behavior of a competitive market for health insurance coverage. Health insurers, called "hospital associations," were found to have engaged individually in cost-control efforts similar to, but possibly more aggressive than, today's utilization review under professional sponsorship. The subsequent disappearance of these insurer-initiated cost controls in Oregon is traced to the medical society's organization of a competing Blue Shield plan as a model of insurer conduct and to a simultaneous boycott by physicians of the hospital associations as long as they persisted in questioning doctors' practices. Some modern parallels are noted, and the advantages of fostering privately sponsored cost-control efforts are suggested.     

Three-area epidemiological study of geographic differences in stroke mortality. I. Background and methods

An epidemiological study was conducted to determine the geographical variations in stroke mortality among three U.S. areas. They were Savannah, Georgia (high stroke rates), Hagerstown, Maryland (intermediate stroke rates) and Pueblo, Colorado (low stroke rates). In each area samples were drawn of the population in the 35--54 age group. The subjects were interviewed and examined to obtain the information required on medical conditions and/or living habits which would characterize each area. A brief medical and family history, as well as demographic and personal data, were obtained by interview. The medical examination included blood pressure, ECG, blood and urine chemistry, height and weight. In all three cities the response rate in the final sample selected was 90% (2,375 individuals) interviewed and 74% (1.939 individuals) examined.     

Cardiovascular and antiarrhythmic effects of aprindine (AC1802) during partial occlusion of a coronary artery in the pig

The effect of intravenously administered aprindine (AC1802) as a prophylactic agent against ventricular arrhythmias was studied in pigs. During the first 30 min of ischaemia 5 of the 22 untreated animals died because of ventricular fibrillation against 1 of the 23 animals pretreated with aprindine (P=0.09). Ventricular tachycardias were observed in 10 untreated animals and in none of the aprindine group (P=0.0002). The incidence of other arrhythmias was significantly less in the aprindine group compared with the untreated group (P less than 0.02).     

Landscape features control river's confluences water quality and tributary fish composition

Rivers networks represent hierarchical dendritic habitats within terrestrial landscapes and differences in connectivity and land use influence dispersal, and consequently biodiversity patterns. We, therefore, measured variation in water chemistry and fish abundance and related these to a number of landscape characteristics (e.g., wetland, urban, wooded, and agricultural) in the River Klarälven and its 30 permanently flowing tributaries. We hypothesized that these environmental attributes would differ between tributary and main stem habitat and that these differences would be driven by landscape attributes including land use. We found considerable intertributary variation in temperature and nutrient levels, and between the tributaries and the main stem. Generally, water temperature was lower in the tributaries, whereas nutrient levels were higher in the tributaries. The lower water temperature has implications for coldwater fishes, and we found two fishes, burbot and lamprey, associated with coldwater tributaries. We also found an inverse relationship between water quality and anthropogenic land use. Protecting tributaries with low anthropogenic impact will likely become increasingly important with ongoing global warming as they can function as thermal refugia for coldwater fishes. Hence, this study underscores the need to evaluate water courses at regional scales to identify spatial refuges and ensure connectivity.     

Enzymatic synthesis of monosaccharide fatty acid esters and their comparison with conventional products

5-O-Acyl-1,2-O-isopropylidene-D-xylofuranose and 6-O-acyl1,2∶3,4-di-O-isopropylidene-D-galactopyranose were enzymatically prepared from the corresponding monosaccharide acetals and commercial (crude) fatty acid mixtures. Subsequent acid-catalyzed hydrolysis of the isopropylidene group(s) gave monosaccharide esters with overall yields of 59–88%, where the monoester content was at least 80% (galactose oleate) and typically 90% for the other preparations. In contrast to sugar fatty acid esters prepared by conventional, high-temperature (trans)esterification, the enzymatically obtained monosaccharide esters contained no appreciable quantities of undersirable side products, and the only contaminants were monosaccharides and fatty acids.