Effects of octylguanidine on the electrical and mechanical events of xenopus heart

The effects of octylguanide on the electrical and mechanical events of Xenopus heart perfused at the rate of 5 ml/m with oxigenated Ringer of ph 7,4 at 24 degrees C were studied. The early effects on the action potential resemble those of the tetrodotoxina, the later effects looks like instead as those observed with metabolic poisons. The cardiac preparations poisoned by octylguanidine still have a metabolic reserve available to furnish energy for the contractile process.     

Lymphotoxin production by human lymphocytes. I. Study of the supernatants of phytohemagglutinin stimulated human lymphocyte cultures]

Lymphotoxin was found to be present in supernatants from 22 human lymphocytes cultures stimulated with phytohemagglutinin in a dose of 5 and 10 microgram/ml. The lymphocytes were obtained from the peripheral blood of 6 apparently healthy persons. Lymphotoxin activity was determined by simple and objective method, i.e. by staining the target cells (mouse L-cells) monolayer with crystal violet, with the following determination of optic densities of the L-cells lysates at 570 nm in the spectrophotometer. As revealed, 1 : 5 dilutions of the supernatants from the lymphocyte cultures incubated for 48 hours inhibited the L-cells growth by from 40 to 60%. With further incubation of the cultures (up to 72 and 96 hours) the cytotoxicity of their supernatants for the target cells showed no increase, whereas the blasttransformation index reaches the maximal value by 72nd incubation hour. Supernatants from unstimulated lymphocyte cultures failed to produce any cytotoxic effect on L-cells.     

Pheromone production, male abundance, body size, and the evolution of elaborate antennae in moths

The males of some species of moths possess elaborate feathery antennae. It is widely assumed that these striking morphological features have evolved through selection for males with greater sensitivity to the female sex pheromone, which is typically released in minute quantities. Accordingly, females of species in which males have elaborate (i.e., pectinate, bipectinate, or quadripectinate) antennae should produce the smallest quantities of pheromone. Alternatively, antennal morphology may be associated with the chemical properties of the pheromone components, with elaborate antennae being associated with pheromones that diffuse more quickly (i.e., have lower molecular weights). Finally, antennal morphology may reflect population structure, with low population abundance selecting for higher sensitivity and hence more elaborate antennae. We conducted a phylogenetic comparative analysis to test these explanations using pheromone chemical data and trapping data for 152 moth species. Elaborate antennae are associated with larger body size (longer forewing length), which suggests a biological cost that smaller moth species cannot bear. Body size is also positively correlated with pheromone titre and negatively correlated with population abundance (estimated by male abundance). Removing the effects of body size revealed no association between the shape of antennae and either pheromone titre, male abundance, or mean molecular weight of the pheromone components. However, among species with elaborate antennae, longer antennae were typically associated with lower male abundances and pheromone compounds with lower molecular weight, suggesting that male distribution and a more rapidly diffusing female sex pheromone may influence the size but not the general shape of male antennae.     

Patterns of the epidemic process in viral hepatitis A and B in territories with different morbidity levels. I. Hepatitis A

On the basis of data obtained by seroepidemiological studies general regularities, as well as essential differences, in the manifestations of the epidemic processes characterized by the active and sluggish spread of infection induced by hepatitis A virus have been revealed.