Further Studies on Cynara Rhabdovirus

Cynara rhabdovirus (CyRV) was isolated from symptomless artichoke plants in southern Italy using Nicotiana langsdorffii as susceptible host and immune serum to artichoke latent virus to eliminate this virus from inoculum. CyRV can infect several solanaceous species, has thermal inactivation point of 40-45°C, dilution end point between 10^?2 and 10^?5 and longevity in vitro at 4 and 20°C of 4-5 days and 6-24 h, respectively. It was purified and used for preparing antisera with homologous titre varying from 1: 16 to 1: 64. In decoration tests, the virus did not react against antisera to eggplant mottled dwarf virus (EMDV) and its antiserum did not decorate ivy vein clearing virus (IVCV). Ultrastructural aspects of CyRV infection in Datura stramonium and Nicotiana glutinosa were very like those described for the same virus in the past except for presence of longer virions which were often encountered in infected cells during this study.     

Further Studies of Porcine Malignant Hyperthermia

A non-lethal procedure for identifying pigs apt to develop malignant hyperthermia is described. Susceptible animals were exposed to a variety of anaesthetic and other agents and it was shown that thiopentone sodium and CT 1341 (Glaxo) afforded a measure of protection against the development of the syndrome. Pretreatment with procaine did not prevent the onset of the condition and the administration of procaine when muscle rigidity was present failed to prevent a fatal outcome. The syndrome was induced in susceptible animals by halothane, chloroform, and a combination of halothane with suxamethonium. The effects of cyclopropane in susceptible pigs could not be predicted, and other tests showed that suxamethonium alone would not induce muscle contracture. Pretreatment with lignocaine failed to prevent induction of the syndrome by halothane.We believe that the porcine syndrome may result from more than one defect and that in one particular type the most effective treatment is immediate cooling coupled with the administration of sodium bicarbonate.     

Further Studies of Gastric Hypersecretion in Chronic Renal Failure

The effect of medical treatment has been studied in four patients with end-stage renal failure who suffered from severe spontaneous gastric hypersecretion, associated with very low levels of intraduodenal pH in two cases. Atropine decreased the overnight gastric acid output, but the residual acid secretion and duodenal content of acid remained dangerously high in one of the patients. Secretin inhibited the basal gastric secretion of acid in all cases and converted the pH of the duodenal contents to alkaline. While atropine cannot be used to control the gastric hypersecretion, secretin may prove to be valuable in the therapeutic management of the gastric hypersecretion of patients with chronic renal failure.     

Further Studies on Substrates Inducing Metacyclogenesis in Trypanosoma cruzi

Epimastigotes of Trypanosoma cruzi, Peru strain, incubated in Contreras' artificial triatomine urine transformed into metacyclic trypomastigotes when 10 mM L-glutamine, L-asparagine or D-fructose was added to the medium. Metacyclogenesis with these substrates was comparable to the percent metacyclic morphotype formation induced by L-proline and significantly greater than that stimulated by 10 mM D-glucose. Sodium acetate (10 mM) increased transformation induced by L-proline, and L-hydroxyproline (10 mM) increased transformation induced by D-fructose. Phosphoenolpyruvate (10 mM) inhibited L-proline-induced metacyclic trypomastigote stage formation. Three antimetabolites, azetidine 2-carboxylate (5 mM), malonic acid (1 mM), and desthiobiotin (5 mM), completely inhibited D-fructose-induced but not L-proline-induced transformation. The Costa Rica, Y, and CL strains of T. cruzi showed different patterns of percent metacyclogenesis with substrates that induce transformation in the Peru strain.     

Further Studies of Sodium Transport in Feline Red Cells

The transport of radioactive sodium in high sodium cat red blood cells has been studied under various experimental conditions. It was found that iodoacetate (IAA) and iodoacetamide (IAM) inhibit Na influx by 50% whereas NaF has no effect. Reversible dyes, such as methylene blue (Mb), also inhibit this influx by 60%. Both IAA and Mb effects show a lag period of about 40 min. Cell starvation abolishes the volume-dependent Na influx which is generally observed in these cells. IAA reduces significantly the volume-dependent Na influx but does not inhibit it completely. 5 mM magnesium chloride produces a twofold increase in Na influx. On the other hand, MgCl₂ has no effect on Na transport in human red cells or on potassium or sulfate transport in cat red cells. The effect of MgCl₂ is quite rapid and does not interfere with the volume-dependent Na influx. This effect is abolished in starved cells. Reincubation of previously stored cells in buffered solutions containing glucose and MgCl₂ causes more than one order of magnitude increase in Na influx. These several observations are discussed in terms of the possibility of a link between Na transport and Na-Mg-activated ATPase.     

Further Studies on Oxalic Acid Biosynthesis in Oxalate-accumulating Plants

l-Ascorbic acid functions as a precursor of oxalic acid in several oxalate-accumulating plants. The present study extends this observation to include Rumex crispus L. (curly dock), Amaranthus retroflexus L. (red root pigweed), Chenopodium album L. (lamb's-quarters), Beta vulgaris L. (sugar beet), Halogeton glomeratus M. Bieb. (halogeton), and Rheum rhabarbarum L. (rhubarb). Several species with low oxalate content are also examined.     

Further Studies on Antigenic Changes in Trypanosoma lewisi*

SYNOPSIS. An investigation of day-to-day changes in adult form antigens of T. lewisi in the rat shows that adult antigens, 2 of which are present in trace amounts in young forms, suddenly appear in large amounts in 9-day-old trypanosomes. An additional antigen is formed on the 13th day. In addition, 2-day-old trypanosomes contain some antigens not present in 6-day-old forms. The combined results of the present paper and a previous one indicate that there are antigenically 3 distinct stages of T. lewisi in the rat: 1- to 3-day-old, 4- to 8-day-old, and 9- to 14-day-old forms. From 9- to 11-day-old trypanosomes, there is a form containing both young and adult antigens.