The determination of purine levels in human and mouse plasma

Variable levels of acetic anhydride have been recommended for addition to one of two reagents used in the glyoxylic acid method for the determination of tryptophan. For use of this reagent immediately after preparation it was shown that a minimum of 16% (v/v) of acetic anhydride should be included in the formulation to obtain near-maximum sensitivity. It was further demonstrated that reagent formulations with and without acetic anhydride changed with exposure to light. The observed changes are manifest as changes in the relative sensitivities of the assay. Several modifications are recommended to improve the sensitivity and stability of the acetic anhydride-containing reagent in this assay.     

Muscle and femoral vein temperatures during short-term maximal exercise in heart failure

Core temperature decreases throughout short-term maximal exercise in heart-failure patients. To investigate possible causes for this unusual response to exercise, we studied core (pulmonary arterial blood), femoral vein, muscle, and skin temperatures in eight patients with severe heart failure who performed maximal upright incremental bicycle exercise to 50 W. A normal group (n = 4) was exercised for comparison. In the heart-failure patients, core temperature was 36.95 +/- 0.37 degrees C at rest, significantly (P less than 0.05) decreased at 25 W of exercise to 36.59 +/- 0.40 degrees C, and at 50 W remained decreased to 36.57 +/- 0.40 degrees C. In comparison, we found that the resting core temperature in the normal subjects was 37.28 +/- 0.34 degrees C, was the same at 25 W (37.29 +/- 0.41 degrees C), and increased significantly (P less than 0.05) to 37.50 +/- 0.32 degrees C at 50 W of exercise. Femoral vein temperature in heart-failure patients (n = 6) was below core temperature throughout exercise to 25 and 50 W (36.22 +/- 0.62 and 36.34 +/- 0.65 degrees C, respectively). Muscle temperature (n = 7) was significantly (P less than 0.05) lower in the heart-failure patients (34.8 +/- 1.1 degrees C) at rest compared with the normal subjects (36.2 +/- 1.0 degrees C). During exercise, muscle temperature increased above core temperature in only four of the heart-failure patients and was significantly (P less than 0.05) lower (36.5 +/- 1.3 degrees C) compared with the normal subjects (38.0 +/- 0.2 degrees C).(ABSTRACT TRUNCATED AT 250 WORDS)     

Differences in membrane lipid composition and fluidity of transplanted GRSL lymphoma cells, depending on their site of growth in the mouse

GRSL lymphoma cells were isolated from various growth sites in the host. The relative membrane lipid fluidities of these cells and of normal lymphoid cells were estimated by fluorescence polarization, using the probe diphenylhexatriene and by measuring the (free) cholesterol/phospholipid molar ratio in whole cells. The results indicate that the membrane fluidity (reciprocal of the lipid structural order) of the lymphoma cells increases in the order of their location: peripheral blood less than spleen less than mesenterial lymph node less than ascites fluid. The membrane fluidities of normal lymphocytes from thymus, mesenterial lymph node and spleen were about the same, but higher than of peripheral blood lymphocytes, and between those of the lymphoma cells from lymph node and spleen. These results are confirmed by more extensive analysis on purified plasma membranes from the splenic and ascitic GRSL lymphoma cells and from normal splenocytes and thymocytes. The significantly higher lipid order parameter found in the GRSL plasma membrane isolated from the spleen as compared to those from the ascites cells could be fully explained by the differences measured in the major chemical determinants of the fluidity, i.e., the cholesterol/phospholipid ratio, the sphingomyelin content and the degree of saturation of the fatty acyl groups of the phospholipids. It was also found that the cholesterol/phospholipid ratio in erythrocyte membranes isolated from the peripheral blood of the tumor bearers was higher than in those from normal control mice. The observed differences in membrane fluidity between distinct subsets of tumor cells may be relevant to the sensitivity of these cells to immune attack or to drugs.     

Histopathological survey of male gonads offish from petroleum production and control sites in the Gulf of Mexico

Testes, collected from 11 species of demersal and platform associated pelagic fishes, were examined microscopically for petroleum induced lesions. The fish were taken from 19 oil and gas production platforms and four control sites from the north-central Gulf of Mexico, during two periods, spring and late summer. The status of the spermatogenic cycle at the time specimens were collected correlated well with the known spawning times for the respective species of fish with one exception. Histopathological evaluation revealed acidophilic granular cells, chromatophores, degeneration and focal leucocytic aggregations as the most prominent and abundant conditions in testes, with encapsulated cysts, protozoa and helminths being observed only rarely. No evidence of adverse effects on gonadal morphology was found.     

Biology of Elodea canadensis mich. and its management in Australian irrigation systems

The seasonal growth and decline of a population of Elodea canadensis Mich. growing in an irrigation drain are described, together with some characteristics of the aquatic environment (turbidity, photosynthetically-available radiation, temperature and pH). Overwintering buds (up to 5000 m^?2) in the form of swollen dormant stem apices are produced in autumn with the onset of cold weather, remain in the mud, and grow out in the spring. In late summer vegetative reproduction also occurs when large numbers of the leafless stem portions which are capable of growing into independent plants are swept downstream from established populations. Results suggest that control measures should be applied in early summer when populations are approaching nuisance size, and again in late summer before fragmentation occurs and overwintering propagules are initiated. In irrigation channels in Australia, where draining and drying are not feasible, biomass in successfully reduced by widespread use of herbicides.