The estimation of carrier rate from amoebic surveys

The purpose of surveys of amoebae or other organisms is the estimation of the carrier rate in a population, that is, of the proportion of persons who carry a given parasite. As a rule, the tests do not infallibly detect the presence of the organism in a known carrier. Thus simple estimation from a single examination of each member of a sample is not applicable.

Some energy-producing systems in Bdellovibrio bacteriovorus, strain 6-5-S

Bdellovibrio bacteriovorus 6-5-S, an obligate bacterial parasite, was grown on cells of Spirillum serpens in 20 l of medium. Maximum numbers of the parasite were attained at 42–55 h, about 2–12 h after there were no viable host cells remaining. Growth of B. bacteriovorus occurred only under aerobic conditions. The organism is rich in catalase. Endogenous respiration of cells and oxidation of NADH by cell extracts is inhibited by cyanide and azide but not by carbon monoxide. Difference spectra indicate the parasite has a cytochrome system and likely couples oxidation to phosphorylation, although efforts to demonstrate fixation of inorganic 32P into organic phosphate failed. Glutamine, glutamate, and asparagine stimulate respiration, and cell extracts contain glutamate and alanine dehydrogenases. B. bacteriovorus 6-5-S also has a tricarboxylic acid cycle, as isocitric dehydrogenase, the α-ketoglutarate dehydrogenase system, succinyl-CoA synthetase, fumarase, and malate dehydrogenase were found in the soluble fraction of the cell extract, and a bound succinic dehydrogenase in the particulate fraction. The glyoxylate cycle may not be present since isocitric lyase could not be detected despite the presence of acetate in the growth medium. Tests on cell extracts for glucose kinase, glucose 6-phosphate dehydrogenase, and 6-phosphogluconate dehydrogenase were also negative. However, aldolase, glyceraldehyde 3-phosphate dehydrogenase, pyruvate kinase, and lactic acid dehydrogenase were present although at rather low levels, indicating that the parasite can obtain energy from the substrate-linked phosphorylations of the glycolytic system.

The influence of anaesthetic agents on the formation of methaemoglobin induced by aniline in cats

Administration of anaesthetic agents modifies the methaemoglobin formation induced by aniline in cats. The maximum amount of methaemoglobin is reduced, so too is the rate at which the methaemoglobin disappears. Studies with phenylhydroxylamine indicate that these changes are due to anaesthetics modifying the metabolism of aniline to phenylhydroxylamine rather than modifying the action of phenylhydroxylamine on systems within the red blood cell. The microsomal metabolism inhibitor SKF 525A has no effect on methaemoglobin formation induced by aniline.

Right atrial myxoma mimicking a rheumatic disorder

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STUDIES WITH STAPHYLOCOCCAL TOXINS: VII. SEPARATION OF A PROTEOLYTIC ENZYME FROM ALPHA HEMOLYSIN

Certain preparations of alpha hemolysin induced dissolution of rabbit and sheep erythrocytes and hydrolyzed casein. Components which were independently hemolytic and proteolytic were separated by the following sequence of procedures: precipitation with zinc acetate and ethyl alcohol at approximately −5 °C and pH 4.0, ion exchange chromatography with carboxymethylcellulose, and zone electrophoresis with granules of potato starch. The comparative lytic activity of the hemolytic component against erythrocytes of the rabbit and of the sheep was 19:1. No separation could be effected between these two hemolytic properties.

Feline Haemobartonellosis - A Case Report

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THE TRICARBOXYLIC ACID CYCLE IN PSEUDOMONAS NIGRIFACIENS

All the enzymes of the tricarboxylic acid cycle, with the exception of oxalosuccinic acid decarboxylase, were detected in sonic extracts of the moderately halophilic bacterium Pseudomonas nigrifaciens. Several of the component enzymes of the cycle exhibited a slight salt requirement; activity of the others was reduced in the presence of added salt. These results are in contrast to the optimal salt requirement of the organism for growth (1.5 to 3.0% NaCl).Apart from the effects of salt on their activities, the component enzymes of the tricarboxylic acid cycle in P. nigrifaciens appear to be similar to those described from other sources.

THE EFFECT OF SALTS ON THE GROWTH OF MICROCOCCUS HALODENITRIFICANS N. SP

A halophilic coccus, Micrococcus halodenitrificans n. sp., isolated from meat curing brines is described. This organism grows optimally in media containing between 4.4 and 8.8% sodium chloride as determined by viable counts and manometric methods. The viable count decreases in media containing 2.2% or less sodium chloride. As salt concentrations increase above 8.8%, the length of the lag phase increases and the rate of growth decreases. The organism exhibits a specific sodium chloride requirement for growth. However, it continues to respire in the presence of sodium bromide.

THE EFFECTS OF SALTS ON THE NITRITASE AND LACTIC ACID DEHYDROGENASE ACTIVITY OFMICROCOCCUS HALODENITRIFICANS

With Micrococcus halodenitrificans, maximum production of nitritase occurs just after nitrite has been reduced completely to nitrogen. Maximum denitrifying activity takes place at pH 7.6 in the presence of 0.38 to 0.75 molar sodium chloride or sodium bromide. The activity is slightly less in the presence of lithium chloride but reaches a peak at 0.19 to 0.38 molar concentration. The reduction of nitrate to nitrite is inhibited by azide whereas reduction of nitrite to nitrogen is not, suggesting the possibility that at least two separate enzymes may be involved in these reactions. The lactic acid dehydrogenase of this organism shows maximum activity in the presence of 0.75 molar sodium chloride.