Inhibitory tripeptide,Lys-Phe-Tyr,as a fragment of physalaemin

Summary Several peptides were separated from-chymotrypsin-treated physalaemin by high voltage paper electrophoresis, and inhibition of the excitability of a molluscan giant neurone (tonically autoactive neurone) by the tripeptide, Lys-Phe-Tyr, was demonstrated.We thank Dr Sadaaki Iwanaga of Osaka University and Dr Atsuo Inoue of Daiichi Pharmaceutical CO for their helpful advice and the donation of the tripeptide (Lys-Phe-Tyr).     

Effects of ACTH and diabetes on phospholipid metabolism in adrenal mitochondria.

Incorporation of 32P into adrenal mitochondrial phospholipids (PL) incrased in ACTH-treated rats, but it decreased in diabetics, inspite of the fact that these animals showed adrenal overacity. Since diabetics did not show increased 11 beta-hydroxylation. as opposed to ACTH-treated rats, it is suggested that the stimulation of this enzyme activity by exogenous ACTH is related to an increased turnover of PL at the mitochondrial membrane. The process is impaired in diabetics and prevents the stimulation of 11 beta-hydroxylation.     

Species difference in the effects of proteolytic enzymes on red cell membrane

Summary Pronase and -chymotrypsin digested the major glycoprotein in the human and mouse red cell membranes and in SDS gel electrophoresis the glycoprotein disappeared accompanied by the appearance of a new band of lower mol.wt. However in the membranes of sheep, rat and rabbit, no digestion was demonstrated. The effects of pronase on anion permeability were almost identical for human and animal erythrocytes.     

Irreversible shock in rats after injection of microspheres into the renal artery

Summary After injection of microspheres into both renal arteries of rats, an irreversible shock syndrome develops, resulting in death within 4–12 h. Ligation of both renal pedicles after injection of microspheres prevents the shock. It is presumed that kininogenases released from the kidneys participate in the pathogenesis of the shock syndrome.These studies were supported in part by the Deutsche Forschungsgemeinschaft within the SFB 90, Cardiovasculäres System.     

Action de l'orientation et de la qualité de la lumière sur le développement des protonémas de Bryales

Summary The radiations coming from Blanc Brillant de Luxe' fluorescent stimulate the growth and ramification of protonema ofCeratodon purpureus (Hedw.) Brid. This stimulation is caused by red light (660 nm). Multidirectional lightening is more favorable than unidirectional exposition.     

Hydrogen peroxide generation inTrypanosoma cruzi

Summary Homogenates from T. cruzi epimastigotes produced 3.4 pmoles H₂O₂/min 10⁶ cells, as detected by the cytochrome c peroxidase assay. Addition of NADH or NADPH increased H₂O₂ production by a factor of 3 and 5, respectively. When supplemented with NADH and NADPH, the mitochondrial, microsomal, and supernatant fractions produced H₂O₂, the soluble fraction and the mitochondrial membranes being apparently the main generators of H₂O₂. The epimastigote homogenates showed cyanide-sensitive superoxide dismutase activity, equivalent to 0.28 g bovine superoxide dismutase per mg homogenate protein.This investigation was supported by grants from Consejo Nacional de Investigaciones Cientificas y Técnicas (CONICET) Argentina and the Scientific Office, American States Organization.Career Investigator of CONICET.     

Sensitivity of the developing chick myocardium to the positive inotropic effects of calcium and isoproterenol

Summary The present results show that the sensitivity of the chick myocardium to the positive motropic effect of Ca⁺⁺ decreases during development and that the Ca⁺⁺ concentration of the physiological solution used must be lowered below normal to study the effects of positive inotropic agents in preparations from younger embryos. Isoproterenol elicits positive inotropic responses in 7–9-day embryonic ventricle and in newborn chick atria; however, the 4-day embryonic myocardium is unresponsive to isoproterenol.This work was supported by Grant No. HL-15995 from the National Heart Institute (USPHS).The authors would like to thank Dr.F. E. Shideman for the isolated tissue baths used in these experiments.     

Lithium exchange in from epithelium: determination of unidirectional flux using the stable isotopes 6Li and 7Li in an ionic analyzer]

The use of the stable isotopes 6 and 7 of lithium, and detection with the ionic analyser, allow the measurement of unidirectional transepithelial Li-fluxes, between "external" and "internal" solutions which both contain 80% Na and 20% Li. Efflux was found to be bigger than influx. An important lag-phase on the curve, reveals the interference of a Li-compartment, with a high capacity, in the epithelium itself.     

Changes in ecdysone levels in the spiderPisaura mirabilis nymphs (Araneae,Pisauridae)

Summary RIA of ecdysones are made on nymphal extracts ofPisaura mirabilis during the intermoulting cycle. The hormone level is low during exuviation and the greatest part of the intermoulting period but increases notably before and after ecdysis. The main hormonal peak or pre-ecdysial peak is due to -ecdysone, characterized by combined TLC/RIA.Acknowledgment. We wish to thank Dr M. Hirn for his help during the manipulations and J. Britton who has translated the text into English.