Leiurus quinquestriatus venom inhibits different kinds of Ca2+-dependent K+ channels

A minor protein component of Leiurus quinquestriatus venom has been reported to inhibit selectively the apamin-insensitive Ca2+-dependent K+ channels of mammalian skeletal muscle (Miller, C., Moczydlowski, E., Latorre, R. and Phillips, M. (1985) Nature 313, 316-318). We report the effect of the venom on both the apamin-insensitive channels of the human erythrocyte, the Ehrlich cell and the rat thymocyte and the apamin-sensitive channel of the guinea pig hepatocyte. The venom inhibited Ca2+-dependent K+ transport in all the cases with a Ki value within the range of 1 to 10 micrograms/ml, similar to that reported previously in muscle. Valinomycin-induced K+ transport was also antagonized by the venom but its sensitivity was about 1/10 as much as that of the Ca2+-dependent K+ channel.     

Specific inhibition of human granulocyte elastase with peptide aldehydes

The kinetic features of human granulocyte elastase, chymotrypsin, porcine pancreatic elastase and elastomucoproteinase were compared. Amino acyl ester substrates were assayed and Km and kcat values were defined. Aldehyde analogues of the p-nitroanilide substrates designed for granulocyte elastase as optimal for Km appeared to be potent inhibitors. Suc-D-Phe-Pro-valinal (Ki = 40 microM) was found to inhibit granulocyte elastase competitively and specifically when measured with synthetic substrates, and the Ki was 3 microM with the natural protein substrate, elastin.     

The Pleistocene lake deposits of the NE Baza Basin (Spain): salinity variations and ostracod succession

The Guadix-Baza Basin in Spain covers an area of approximately 3000 km² and yields a sedimentary sequence ranging from Lower Miocene to Pleistocene. Twenty five meters of Lower Pleistocene lacustrine sediments have been located in the NE part of the Basin at about 1000 meters in altitude. This sequence which overlies dolomitic mud flat deposits consists of limestones, calcareous and dolomitic mudstones, dolostones, silty clays, sands and gravels. Salinity fluctuations and short dry episodes, related to lake level oscillations, have been recorded by textural, mineralogical and faunal changes throughout the sequence. Ostracods, which are the most commonly encountered fossils, permit to detect recurrent changes in water salinity and regime, and solute composition. The faunal changes indicate an alternation of slightly saline and bicarbonate-rich water (when ostracods and gastropods occur) with a saline NaCl-dominant water (in which ostracods, Cerastoderma bivalves and non-marine foraminifers are found).The frequent and recurrent hydrochemical changes in the Baza Basin in the Early Pleistocene point to a climate of high contrast like in the Mediterranean region today but with a greater availability of water within the system compared to the present situation in the area.     

Purification and properties of a coagulant proteinase isolated from bushmaster (Lachesis muta) venom (Serpentes: Viperidae)

The venom of Lachesis muta is a rich source of a thrombin-like enzyme. Its coagulant proteinase was purified by DEAE -Sephadex A -50 followed by agmatine CH -Sepharose and gel filtration on Sephadex G-100. On polyacrylamide gel electrophoresis at pH 8.4 a single band was observed. Its molecular weight by gel filtration was 49,000. The coagulant and esterolytic activities toward human fibrinogen and Tame of the inudasa were 662 NIH units/mg of protein and 4.37 delta OD225/min x 10(-3)/micrograms/ml, respectively. These values represent 23 and 5.7 fold increase over the crude venom. The enzyme mudasa, was evaluated with serum from human patients at Hospital Nacional de Ni?os Dr. Carlos Sáenz Herrera and found to be a valuable reagent for the quantification of fibrinogen on heparinized plasma.     

Postnatal development of amino acid metabolism enzymes in the liver and muscle of 'cafeteria' rats

The effect of feeding a high-energy highly palatable cafeteria diet on the liver and muscle ontogenesis of serine dehydratase, alanine transaminase, glutamine synthetase and adenylate deaminase during postnatal development of the rat has been studied. The results are in agreement with the lower amino acid utilization in cafeteria rats, both adults and during postnatal development. The feeding of excess energy coupled with high-quality protein resulted in changes in the ontogenesis of the studied enzymes that coincide with the development of protein synthesis and overall pup growth even before they had direct access to this rich diet, suggesting that cafeteria feeding already affects the amino acid metabolism of the pup through the dam's milk.     

Effect of chemical sympathectomy on renal hydroelectrolytic handling in dogs with chronic caval constriction

The effect of renal selective chemical sympathectomy by intrarenal infusion of 6-hydroxydopamine (6-OHDA, 5 mg/kg body weight) on the renal excretion of water and electrolytes was studied in 7 dogs in whom a syndrome of sodium and water retention and ascites formation was induced by partial constriction of thoracic inferior vena cava. Propranolol (1 mg) and phentolamine (3 mg) were also injected to obviate acute systemic hemodynamic changes. Sympathectomy was performed once in 4 dogs and three times in 3 dogs. Sympathectomy induced an abrupt and transient increase in urinary flow (from 170 +/- 30 to 890 +/- 60 ml/24 h) and sodium excretion (from 4.5 +/- 1.5 to 178 +/- 21 mEq/24 h). This was accompanied by an important fall in plasma renin activity (from 2.2 +/- 0.2 to 0.5 +/- 0.1 ng angiotensin I/ml/h) and aldosterone, and disappearance of ascites. It is concluded that chemical sympathectomy, by increasing renal sodium and water excretion, mobilizes the ascites induced by chronic caval constriction, a fact that highlights the role of the renal sympathetic system in the pathogenesis of sodium and water retention by the kidney.