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M Wasserman

Publications and source records attributed to M Wasserman.

At least 55 records · Page 3Linked to original sources
PubMed1983

Separation and concentration of schizonts of Plasmodium falciparum by Percoll gradients.

A technique for the separation of schizonts of Plasmodium falciparum is described. The different stages of the asexual cell cycle of the parasite were positioned according to their density in a continuous gradient of Percoll. Young trophozoites coincided with erythrocytes in a broad band corresponding to densities from 1.075 to 1.100 g/ml, whereas schizonts were concentrated at a density approximating 1.062 g/ml. The viability of the parasites was unimpaired by this procedure. Young trophozoites and schizonts continued their normal life cycle when cultured after the separation procedure. The percentage of recovery was high, reaching 80% of the initial quantity. Possible applications of the technique are discussed.

Animals↗
PubMed1983

Acute renal failure secondary to myoglobinuria associated with Legionnaires' disease.

A case of nonfatal Legionnaires' disease was complicated by rhabdomyolysis, myoglobinuria, and acute nonoliguric renal failure. It was not determined whether the rhabdomyolysis was secondary to direct toxic effect of the organism or due to a circulating factor causing muscle necrosis. This case provides additional evidence that rhabdomyolysis with subsequent renal failure may be a serious complication of Legionnaires' disease.

Acute Kidney Injury↗
PubMed1982

Effects of Ca++ depletion on the asexual cell cycle of Plasmodium falciparum.

Ca++ was shown to be indispensable for the normal growth of cultures of Plasmodium falciparum. Inclusion of ethyleneglycolbis (beta-amino-ethylether) N,N'-tetra-acetic acid (EGTA) caused blocking of the asexual cell cycle of the parasite in two sites, the first blockage occurring between 20 and 26 hours after invasion of the erythrocyte. It proved to be irreversible by additions of Mg++ or Ca++, and to lead to morphologically abnormal parasites arrested in the mature trophozoite stage of the cycle. The second site of inhibition was probably one of the steps in the process of invasion of the erythrocyte by the merozoite. When 1 mM EGTA was added 24--30 hours after the culture was synchronized the cell cycle of the parasite continued without any interference in the normal maturation until the development of schizonts and release of merozoites into the medium. However, reinvasion of fresh erythrocytes by these merozoites was impeded. The inhibition of reinvasion caused by EGTA was overcome by the addition of an excess of Ca++ but not by an excess of Mg++. After the addition of Ca++ to cultures blocked just before the invasion phase as schizonts, the merozoites were again rendered fully infective and the rate of invasion was similar to that in an untreated control culture. Implications of the effects of Ca++ depletion on the asexual cell cycle and possible applications of EGTA as a reversible inhibitor of the invasion process are discussed.

Calcium↗
PubMed1977

Role of Ca2+ in preserving viability of Friend erythroleukaemic cells after ultramicroinjection.

Ca2+ facilitated the fusion by Sendai virus of Friend erythroleukaemic cells and Ehrlich ascites tumour cells but not that of hepatoma tissue culture cells. In the absence of Ca2+ Sendai virus caused the complete depletion of ATP and abolished protein synthesis in Friend erythro-leukaemic cells fused with each other. Addition of high concentrations of Ca2+ (10-20 mM) partially protected the cells from ATP depletion. After a further incubation of cells in complete medium plus 0.2 mM adenine, ATP levels and protein synthesis were restored to 60-85% of those of the untreated control. The protective effect of Ca2+ was used to improve the ultramicroinjection method which involves the fusion of human erythrocyte ghosts with cells. When human erythrocyte ghosts containing high K+ were fused with Friend erythroleukaemic cells in the presence of 10 mM Ca2+ ATP levels and protein synthesis after recovery were about 60-85% of the control. Friend erythroleukaemic cells subjected to ultramicroinjection under these conditions had a cloning efficiency of 75-95% of that of the untreated controls. In these experiments 70-100% of the cells had fused with ghosts. Induction of haemoglobin synthesis by dimethylsulphoxide was unimpaired in cells subjected to ultramicroinjection under the same conditions.

Adenosine Triphosphate↗
PubMed1976

A quantitative study of ultramicroinjection of macromolecules into animal cells.

Improvements in the technique of ultramicroinjection of macromolecules into animal cells are described. The method is based on the Sendai virus-induced fusion of animal cells with erythrocyte ghosts containing trapped macromolecules. Fusion of hepatoma tissue culture (HTC) cells with ghosts prepared by hemolysis of erythrocytes in the presence of cytochrome C is much more efficient than fusion with ghosts prepared in the presence of bovine serum albumin (BSA) as in previous investigations. La+++ is more fficient in promoting fusion and less toxic to cells than Mn++, which was used previously. Thus in all subsequent experiments, erythrocytes were hemolyzed in the presence of cytochrome C plus other macromolecules to be trapped, and the resultant ghosts fused in the presence of La+++. The percentage of HTC cells which fused with ghosts reached 80% in many experiments. Ghosts containing 125I-BSA were used to measure the number of BSA molecules injected into HTC cells. About 10(6) BSA molecules were injected per fused cell. The overall efficiency of injection was low (about 0.02% of the starting material).

Amino Acids↗
PubMed1975

Fitness of karyotypes in Drosophila pseudoobscura.

In the dynamics of the survival of chromosomal polymorphism selection may be operating at the genic level, at the chromosomal level or at the supergene level. Tests designed to distinguish between these levels were run on Drosophila pseudoobscura. There was no evidence for heterosis, a necessary requirement for gene-determined chromosomal polymorphism A strong chromosmal selection was observed. No evidence was found for the presence within one locality of more than a single superallele for each supergene (equals gene order). These results are compared to those found by others.

Alleles↗
PubMed1972

Factors influencing fitness in chromosomal strains in Drosophila subobscura.

Chromosomal polymorphism can be maintained by means of genic dominance, genic overdominance, recombination effects and karyotype selection. Experiments were carried out which allow us to distinguish among these factors as they effect egg hatch and larva-to-adult survival in D. subobscura. A strong karotype selection was observed. A small but highly significant recombination effect was also observed despite the fact that the material used in the experiment consisted of inbred, related strains and was therefore less likely to show such an effect than strains randomly chosen from a population. On the other hand, these strains, being inbred, were more likely to show genic dominance or genic overdominance than randomly picked samples. However neither genic dominance nor genic overdominance was detected.

Animals↗
PubMed1970

1-Isopropylamino-3-(4-indanoxy)-2-propanol HC1: a potent beta-adrenoreceptor antagonist.

1. The beta-adrenoceptor blocking activity of 1-isopropylamino-3-(4-indanoxy)-2-propanol HCl (USVC 6524) was determined in the anaesthetized dog, the isolated rat uterus and the isolated guinea-pig tracheal strip.2. USVC 6524 inhibited the positive inotropic, positive chronotropic and vasodilator responses to isoprenaline in the dog in a dose of 10 mug/kg and higher. On the basis of comparative pA(2) values, USVC 6524 is approximately 10 times more potent as a beta-adrenoceptor antagonist than propranolol.3. Cardiac depressant effects produced by USVC 6524 were relatively mild and occurred only after the onset of a strong beta-adrenoceptor blockade.4. USVC 6524 also blocked beta-adrenoceptors in the isolated rat uterus and guinea-pig tracheal spiral strip.

Adrenergic beta-Antagonists↗
PubMedDate not supplied

Cytological differentiation and sexual isolation between populations of Drosophila nigricruria.

Drosophila nigricruria has a distribution ranging from northern Mexico to Chile. It is a relatively rare species, primarily limited to cactus deserts or pine-oak associations at altitudes of 1200 to 2100 meters above sea level. The species comprises two cytological races with a zone of hybridization in the Oaxaca and Puebla regions of Mexico. Despite the zone of hybridization, gene flow for chromosome 4 genes is limited, or non-existent, between the two races. Sexual isolation tests were run using a population from the northern race, a hybrid population, and a population that is essentially southern. Sexual discrimination among these strains was on the same order of magnitude as that found between geographical populations of other species. There was no evidence to indicate that sexual isolation is any stronger between the cytological races of nigricruria than one might expect between any two geographical populations within a species.

Animals↗