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Biomedical subjects

W Leon

Publications and source records attributed to W Leon.

At least 37 records · Page 2Linked to original sources
PubMed1979

The effect of lampit on Trypanosoma cruzi in mice organs and in the bloodstream.

Mice infected with bloodstream forms of Trypanosoma cruzi were treated with an active Nitrofuran compound (Nifurtimox, Lampit). Determination of the number of intracellular forms of T. cruzi in the liver and the spleen of control and Lampit-treated mice showed that the drug induced a decrease in the number of parasites inside the cells. A decrease in the number of bloodstream forms was also observed. Ultrastructural observations showed that Lampit induces several alterations in T. cruzi, the most characteristic alteration being the appearance of dense masses localized in the mitochondrial matrix of the parasites.

Animals↗
PubMed1979

Acetate oxidation by bloodstream forms of Trypanosoma cruzi.

Bloodstream forms of Trypanosoma cruzi had a substantial increase in respiration in the presence of acetate. Oxidation of acetate took place via the tricarboxylic acid cycle and involved an antimycin A-sensitive respiratory pathway. Oxygen uptake in the presence of acetate was a sensitive to antimycin A inhibition as was CO2 production. There was a 6--7% residual O2 uptake which was not inhibited by high antimycin concentrations. Human anti-T. cruzi sera had no effect on oxygen uptake.

Acetates↗
PubMed1979

Antibody-induced capping of the intracellular stage of Trypanosoma cruzi.

Intracellular-stage Trypanosoma cruzi were isolated from infected mice. The effect of specific human antibodies on the membrane surface antigens was studied in vitro, using the immunofluorescent technique. The immune serum induced the aggregation of surface antigens, forming polar caps on the amastigotes.

Animals↗
PubMed1978

Sequence arrangement of the 16S and 26S rRNA genes in the pathogenic haemoflagellate Leishmania donovani.

Kinetic and chemical analysis show that the haploid genome of Leishmania donovani has between 4.6 and 6.5 X 10(7) Kb pairs of DNA. Cot analysis shows that the genome contains 12% rapidly reassociating DNA, U3% middle repetitive DNA with an average reiteration frequency of 77 and 62% single copy DNA. Saturation hybridization experiments show that 0.82% of the nuclear DNA is occupied by rRNA coding sequences. The average repetition frequency of these sequences is determined to be 166. Sedimentation velocity studies indicate the two major rRNA species have sedimentation values of 26S and 16S, respectively. The arrangement of the rRNA genes and their spacer sequences on long strands of purified rDNA has been determined by the examination of the structure of rRNA:DNA hybrids prepared for electron microscopy by the gene 32-ethidium bromide technique. Long DNA strands are observed to contain several gene sets (16S + 26S). One repeat unit contains the following sequences in the order given: (a) A 16S gene of length 2.12 Kb, (b) An internal transcribed spacer (Spl) of length 1.23 Kb, which contains a short sequence that may code for a 5.8S rRNA, (C) 26S gene with a length of 4.31 Kb which contains an internal gap region of length 0.581 Ib, (d) An external spacer of average length 5.85 Kb.

Animals↗
PubMed1978

Effect of ethidium bromide on growth and morphology of Leishmania tarentolae promastigotes in vitro.

Incubation of Leishmania tarentolae promastigotes in 0.01 microgram/ml ethidium bromide in Neo Ye medium for 96 h resulted in 60% inhibition of cell growth and 91% dyskinetoplasty. After 48 h incubation in ethidium bromide over 50% of the cells were scored dyskinetoplastic by light microscopy although the electron microscopical examination revealed that most promastigotes contained at least a small amount of kDNA. A few of the treated cells undergoing division contained two kinetoplasts--one devoid of kDNA and the other with a reduced amount of kDNA as seen in the electron micrographs.

Ethidium↗
PubMed1977

Effect of berenil on growth, mitochondrial DNA and respiration of Leishmania tarentolae promastigotes.

Incubation of Leishmania tarentolae promastigotes in 1.0 microgram/ml Berenil for 96 hr resulted in approximately 33% inhibition of cell growth and approximately 42.5% dyskinetoplasty in the cell population. The buoyant density of kinetoplast DNA (kDNA), p = 1.703 g/ml, remained unchanged after 96-hr exposure to the drug. Endogenous respiration as well as proline- and glucose-induced respiration dropped markedly after 36-hr exposure to Berenil. This drop occurred approximately 12 hr before the onset of dyskinetoplasty, a result which suggests that this drug adversely affects mitochondrial respiratory activity of the promastigotes.

Amidines↗
PubMed1975

Toxicity of 4-nitroquinoline 1-oxide for Crithidia fasciculata.

Growth inhibition of Crithidia fasciculata by 4-nitroquinoline 1-oxide (NQO) was observed in defined and complex media at 28 C. Aromatic amino acids, cystein, and nicotinic acid, among several other substances, were ineffective in overcoming NQO toxicity. Dicoumarol and bovine albumin reversed NQO inhibition. While bovine albumin probably acted by the extra-cellular binding of NQO, dicoumarol inhibited the activity of DT-diaphorase, which reduces NQO to 4-hydroxyaminonitroquinoline 1-oxide (HAQO). The DT-diaphorase from C. fasciculata had the same characteristics as the enzyme from rat liver. The specific protection by dicoumarol against NQO inhibition suggests that HAQO is the active toxic substance for C. fasciculata.

4-Hydroxyaminoquinoline-1-oxide↗
PubMed1975

Therapeutic splenectomy.

An eight-year experience at Charity Hosptial and Touro Infirmary indicates that 10 percent of splenectomies were performed for reasons other than trauma or malignancy. Fifty-nine per cent of therapeutic splenectomies were done for congenital spherocytosis or idiopathic thromboytopenic purpura. All patients having spherocytosis and 57 per cent having ITP had favorable response following splenctomy. Seven surgical death occurred following 69 splenectomies (mortality 10%). Three deaths were from pulmonary emboli, three from hemorrhagic disorders and one from peritonitis. Eighteen postopertive complications occurred, the most frequent being thromboembolic disease. Prophylactic anticoagulants were not used in any patient.

Anemia, Hemolytic↗