Effect of a fall of blood pressure on the release of catecholamines in the hypothalamus

The posterior hypothalamus of anaesthetized cats was superfused through a push-pull cannula and the release of endogenous catecholamines was determined in the superfusate which was continuously collected in 15 min periods. Fall in blood pressure elicited by nitroprusside or bleeding led to an increased rate of release of noradrenaline, adrenaline and dopamine in the hypothalamus. Transection of the brain causal to hypothalamus greatly reduced the rate of resting release of the catecholamines and abolished the enhancing effects of bleeding and nitroprusside. Determination of the catecholamines in samples which were collected in 90 s periods suggested a different pattern of release of the three catecholamines. Further shortening of the collection period (10 s) showed that the fall in blood pressure immediately increased the release of dopamine, while the rates of release of noradrenaline and adrenaline were increased gradually. Hypotension did not influence the rates of release of the catecholamines in the anterior hypothalamus. It is concluded that dopamine, adrenaline and noradrenaline systems of the hypothalamus are involved in the regulation of the arterial blood pressure. The different patterns of release might indicate that dopamine exerts a different function from those of noradrenaline and adrenaline in the normalization of the blood pressure after acute hypotension.     

Principal component analysis of interrelations in stored-wheat ecosystems infested with multiple species of insects

Principal component analysis (PCA) was used to determine the effects of infestation of bulk stored wheat by multiple species of insects at 30±2°C for 60 wk. Eight 204-liter drums containing wheat at 15.5% moisture content were used as three distinct man-made ecosystems: (a) Control system (2 drums), insect-free; (b) RST system (3 drums), artificially infested with Rhyzopertha dominica (F.),Sitophilus oryzae (L.), and Tribolium castaneum (Herbst ); and (c) COT system (3 drums), infested with Cryptolestes ferrugineus (Stephens ),Oryzaephilus surinamensis (L.), and Tribolium castaneum. The variables measured tri-weekly within each system included carbon dioxide, oxygen, temperature, grain moisture, seed damage, grain weight and volume, dust weight and volume, fat acidity values (FAV) of the wheat, seed germination, microflora including Alternaria alternata(Fr.) Keissler ,Aspergillus glaucus group, Aspergillus candidusLink , and bacteria, insects and the mite Tarsonemus granariusLindquist . PCA provided multivariate synopsis of the data quantifying several important relationships among the variables monitored. Tri-weekly and cumulative 60-wk analyses of each system showed that high bacterial counts were associated with high FAV levels;Tarsonemus numbers were positively related to Aspergillus; Alternaria and seed germination were negatively related to FAV, bacteria and grain damage; and that the number of insects was related to the presence of Aspergillus and negatively related to the presence of bacteria. Seed germination and Alternaria infection often decrease rapidly presumably because of infection by fungi of the Aspergillus glaucus group. The combined action of R. dominica and Aspergillus spp. enhanced seed damage and increased grain moisture content thus promoting bacterial growth which in turn inhibited insect and mold growth. Fat acidity values increased with time unless seed damage and bacterial infection were extensive as in the RST system.     

Induction of carboxymethylcellulase inMacrophomina phaseolina

Macrophomina phaseolina, the well-known jute pathogenic fungus produces very low levels of both extra- and intracellular carboxymethylcellulase even in the absence of any cellulose as carbon source in the medium. However, the production of these enzymes is greatly induced by soluble carboxymethylcellulose. The carboxymethylcellulase inM.phaseolina is repressed by glucose.     

Interaction of antitumor drugs with human erythrocyte ghost membranes and mastocytoma P815: a spin label study.

The cytotoxic and mutagenic properties of antitumor drugs such as adriamycin, acridines, diacridine, actinomycin D and Pt compounds are related to their interaction with nucleic acids and inhibition of protein synthesis. We have examined their interaction with human erythrocyte ghost membranes and murine mastocytoma cells using spin labeling techniques. These drugs induce changes in electron spin resonance of the spin labeled ghost membranes and in the mastocytoma cells. These alterations suggest that these drugs induce changes in protein conformation of the membranes. The membrane binding properties of these drugs may be important in their mechanism of action.     

Biochemical mechanism of nitrofurantoin resistance inVibrio el tor

Vibrio el tor cells contain a constitutive reductase enzyme which converts nitrofurantoin to an active principle that is responsible for the observed antibacterial activity of the drug. Acquisition of resistance of this strain towards nitrofurantoin is associated with the loss of this reductase. This enzyme is located in the periplasmic region of the nitrofurantoin-sensitive cells, and seems to play an important role in transporting the drug into the cells.     

Structural investigations of DNA-histone complexes. A spin label study.

We have prepared two acridine spin labels, 6-chloro-9-[4-(2,2,6,6-tetramethyl-1-piperidinyloxy)amino]-2-methoxyacridine (I) and 9-[4-(2,2,6,6-tetramethyl-1-piperidinyloxy)amino]-acridine (II) and have used them to study the binding of lysine-rich histone (H1) to DNA using electron spin resonance (ESR). ESR spectra of I in the presence of DNA, polydA-polydT and polydG-polydC were characteristic of highly immobilized radicals with maximum hyperfine splitting (2T11) of 59G, 62.5G and 59G respectively. However, the 2T11 values for II in the same systems were 55.5G, 55.5G and 62.5G respectively. Addition of H1 at a low P/D released ionically bound I and II from DNA. In the presence of 0.1 M NaCl, which prevents ionic binding, H1 still caused a significant release of bound II but not I from DNA. At a high P/D (with or without NaCl) H1 caused no displacement of either I or II. Our findings suggest that H1 does not affect the intercalating sites and probably binds to one of the grooves of DNA, most probably the major groove, and specifically in the A-T-rich regions.     

Ferritin as an exogenous yolk protein in snails

Summary A main yolk component in the oocytes of the pulmonate snailPlanorbarius corneus L. has been isolated and identified as the iron storage protein ferritin by its ultrastructure, iron content, immuunological properties and behaviour in disc electrophoresis. As judged from acrylamide electrophoresis data and ultrastructural observations, yolk ferritin is an exogenous protein which is synthesised in the hepatopancreas and taken up by the oocytes by endocytosis.     

Salt distribution around roots of wheat under different transpiration rates

Summary Magnitude of Na and Cl accumulation around wheat roots was studied under different transpiration conditions in a loamy sand soil salinized with sodium chloride to an electrical conductivity of 4.1 mmho/cm in the saturation extract. A significant correlation was observed between rate of water loss per unit root length and Na and Cl content of the soil closely adhering to the roots. Under high transpiration condition, maximum ion accumulation occurred in the apparent free space of roots followed by the soil closely adhering to the roots. Results indicate that salt concentration at the root surface is markedly altered under the influence of transpiration rate such that under high transpiration conditions, the plant roots may be exposed to a much higher salt concentration than that anticipated from an analysis of the bulk soil samples.Department of Soil and Water EngineeringDepartment of Soils     

Effect of sodium butyrate on mammalian cells in culture: a review.

Sodium butyrate produces reversible changes in morphology, growth rate, and enzyme activities of several mammalian cell types in culture. Some of these changes are similar to those produced by agents which increase the intracellular level of adenosine 3',5'-cyclic monophosphate (cAMP) or by analogs of cAMP. Sodium butyrate increases the intracellular level of cAMP by about two fold in neuroblastoma cells; therefore, some of the effects of sodium butyrate on these cells may in part be mediated by cAMP. Sodium butyrate appears to have properties of a good chemotherapeutic agent for neuroblastoma tumors because the treatment of neuroblastoma cells in culture causes cell death and "differentiation"; however, it is either innocuous or produces reversible morphological and biochemical alterations in other cell types.