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Biomedical subjects

F Ebert

Publications and source records attributed to F Ebert.

At least 37 records · Page 2Linked to original sources
PubMed1982

The use of isoelectrofocusing in thin layer polyacrylamide and agarose gels as a method for the characterization of Venezuelan Trypanosoma cruzi stocks.

The technique of isoelectrofocusing has been used to compare culture forms of 12 stocks of T. cruzi isolated in different regions of Venezuela. The following seven enzymes have been used for the characterization: unspecific esterase (E.C.3.1.1), malate dehydrogenase (E.C.1.1.1.37), "malic enzyme" (E.C.1.1.1.40), hexokinase (E.C.2.7.1.1), phosphoglucomutase (E.C.2.7.5.1), glucosephosphate isomerase (E.C.5.3.1.9) and glucose-6-phosphate dehydrogenase (E.C.1.1.1.49). The isoelectrofocusing method allows to determine reproducible enzyme patterns of high selectivity and with a number of bands. This permits to recognize possible differences within the T. cruzi-complex much easier than previous methods. The Venezuelan T. cruzi stocks showed a remarkable homogenous behaviour concerning the enzyme profiles. Most of them were identical. Different types seen for "malic enzyme", phosphoglucomutase, and glucose-6-phosphate dehydrogenase were observed in only three stocks, It was not possible to find a clear relationship between the types and the histories of stocks.

Animals↗
PubMed1982

The identification of two main-groups of Trypanosoma cruzi stocks from Brazil by their isoenzyme patterns of isoelectrofocusing.

The isoelectrofocusing of seven enzymes was studied using extracts of 40 Brazilian stocks of T. cruzi culture forms. Four enzymes showed intraspecific variation in enzyme profiles and were selected for characterization of T. cruzi. These enzymes are: nonspecific esterase (E.C.3.1.1), phosphoglucomutase (E.C. 2.7.5.1), glucose-6-phosphate dehydrogenase (E.C. 1.1.1.49) and glucosephosphate isomerase (E.C. 5.3.1.9). The parasite stocks were isolated from endemic areas in the States: Rio Grande do Sul, Sao Paulo, Espirito Santo, Minas Gerais and Bahia. By combining the electrophoretic patterns of the four enzymes concerned the stocks have been classified into two main-groups. Stocks of group I were exclusively isolated from wild animal reservoirs, whereas group II was mainly composed of stocks from human cases and domestic hosts. Only three "sylvatic" stocks have been found in group II. The enzymes glucose-6-phosphate dehydrogenase and glucosephosphate isomerase showed further subtypes within both groups I and II; their significance is not yet clear. The results are in support of the existence of a domestic and a sylvatic transmission cycles in Brazil which are either clearly distinct or overlapping in some areas.

Animals↗
PubMed1979

Evidence for NADH- and NADPH-linked glutamate dehydrogenases in Trypanosoma cruzi epimastigotes.

Two glutamate dehydrogenases, NADH-linked (EC 1.2.1.2) and NADPH-linked (EC 1.2.1.4) were isolated from the epimastigote forms of Trypanosoma cruzi and purified. Both enzymes exist as hexamers. The molecular weights of the native NADH-and NADPH-linked glutamate dehydrogenases were estimated to be 360,000 and 265,000, respectively, and those of the subunits to be 58,000 and 43,000, respectively. The isoelectric point of the NADH-linked dehydrogenase is at pH 5.25 and that of the NADPH-linked enzyme at pH 5.1. The activities of both enzymes are regulated by product inhibition. In addition, purine nucleotides were shown to be potent inhibitors of the NADH-linked glutamate dehydrogenase.

Animals↗
PubMed1979

Effect of polyamines on protein kinases activities from Trypanosoma cruzi.

An interaction of polyamines with protein kinases activities from T. cruzi epimastigotes is demonstrated. Spermine and spermidine and less pronounced putrescine are found to inhibit protein kinases activities. In the extract of T. cruzi three protein kinases are distinguished on account of molecular weight (greater than 200 000, 95 000 and 40 000) and preference for acceptor proteins (phosvitin and histones). Especially the activity of the high molecular weight protein kinase which phosphorylates phosvitin is strongly inhibited by spermine and spermidine. The type of inhibition by both polyamines is found to be non-competitive with respect to ATP as well as phosvitin. The inhibition constants for spermine and spermidine are determined to be 1.4 mM and 2.0 nM, respectively.

Animals↗
PubMed1978

Leishmania donovani: ultrastructural localization of diaminobenzidine reactivity in the amastigotes.

Intracellular amastigotes of Leishmania donovani obtained from spleens of infected hamsters were studied by means of the diaminobenzidine technique for the presence of cytochromes and the activities of cytochrome oxidase and peroxidase. In the absence of H2O2, the oxidation of DAB, evidenced by electron-dense deposits localized on the cristae, inclusions, and enveloping membranes of the mitochondria and kinetoplast, revealed the activity of the cytochrome oxidase and the presence of the cytochromes. The increased deposition of DAB oxidation especially on the enveloping membranes in the presence of H2O2 suggests the activity of a peroxidase, probably cytochrome c peroxidase.

3,3'-Diaminobenzidine↗
PubMed1978

Effect of cyclic AMP on transformation and proliferation of leishmania cells.

A correlation between cyclic AMP (adenosine 3' : 5'-monophosphate) concentration within Leishmania cells and proliferation and transformation is demonstrated. By addition of dibutyryl cyclic AMP and cyclic AMP-phosphodiesterase inhibitors to the culture medium the intracellular level of cyclic AMP was increased. In the presence of 1mM caffeine the level of cyclic AMP accumulated in L. tropica promastigotes from 90 pmoles up to 380 pmoles per 10(9) cells, whereas the proliferation rate decreased to 50%. In the case of L. donovani the transformation of amastigotes to promastigotes was inhibited by addition of dibutyryl cyclic AMP as well as caffeine and papaverine. Especially caffeine (2mM) and papaverine (0.1mM) reduced the transformation rate to less than 5% after 48 h, compared to 35% of the control.

Bucladesine↗
PubMed1978

Protein typing by disc electrophoresis of some species of trypanosomes with special emphasis to Trypanosoma cruzi.

Proteins extracted from culture forms of T. cruzi, T. cruzi-like strains, T. rangeli, T. conhorrini and T. dionisii were separated by disc electrophoresis. The electrophoretic protein patterns of all strains examined were highly reproducible. The results indicate that each of these strains have their own "fingerprints" and the trypanosoma species could be identified by some typical specific protein bands. However, it was not possible to distinguish between the human strains of T. cruzi and the T. cruzi-like strains isolated from other sources.

Electrophoresis, Disc↗
PubMed1978

Cutaneous leishmaniasis in Eastern Saudi Arabia. Epidemiological and clinical features in a nonimmune population living in an endemic area.

Cutaneous leishmaniasis is endemic in Saudi-Arabia. Nonimmune Europeans and their families living temporarily in this area were affected by the disease in great number, resembling an epidemic outbreak. Clinical features and treatment of the disease, problems of re-infection and immunity, as well as epidemiological factors are discussed. Using biochemical methods the parasite was identified as Leishmania tropical major.

Adolescent↗
PubMed1977

Inhibition of protein kinase activity from Trypanosoma cruzi and Trypanosoma gambiense by 3'-deoxyadenosine.

3'-Deoxydadenosine was found to be a potent inhibitor of nucleoside-stimulated protein kinase activity from culture forms of Trypanosoma cruzi and bloodstream forms of Trypanosoma gambiense. The type of inhibition by 3'-deoxyadenosine was competitive with respect to ATP. The inhibition constants for 3'-deoxyadenosine were determined to be 0.11mM and 0.085mM for the enzyme from T. cruzi and T. gambiense, respectively. The apparent Km value for ATP was 0.2mM for both enzymes. 2'-Deoxyadenosine was less effective as inhibitor of the protein kinase activity. The inhibition constants were calculated to be 0.8mM and 0.67mM, respectively.

Adenosine Triphosphate↗
PubMed1977

Ultrastructural localization of diaminobenzidine reactivity in leishmania donovani promastigotes.

The ultrastructural localization of the activities of two enzyme systems in the culture forms of Leishmania donovani was shown by means of the diaminobenzidine techniques. The consistent deposition of electron dense reaction product of DAB oxidation without H2O2 in the kinetoplast and mitochondrial cristae and membranes was taken as evidence of the presence of cytochrome oxidase activity and cytochrome c. In the presence of H2O2, a more intense DAB oxidation was attributed to the activity of a peroxidase, possibly cytochrome c peroxidase. Mitochondrial and kinetoplast reactions to DAB were completely inhibited by KCN, methanol-nitroprusside, and by heating to 50 degrees C for 10 min. On the other hand, no inhibitory effect was observed with 100 mM 3-amino-1,2,4-triazole. Under all conditions of incubation tested, the microbodies were completely unreactive to DAB staining, which was utilized as the basis for their identification. These organelles are rounded, moderately electron-opaque bodies with a finely granular matrix and fine tubules or cores and are limited by a single membrane. Under normal staining method, the microbodies were indistinguishable from the rounded sections of mitochondria.

3,3'-Diaminobenzidine↗
PubMed1976

Cutaneous leishmaniasis in the Libyan Arab Republic: distribution of the disease and identity of the parasite.

The endemicity of cutaneous leishmaniasis in northwest Libya was confirmed. Although the strains isolated from man had variable biological properties they were all biochemically similar according to the tests used. The Libyan strains resemble those of zoonotic cutaneous leishmaniasis in parts of the Middle East, but can be differentiated from urban or highland strains. It is suggested that the recent discovery of the disease is due partly to the improvement in medical services, and partly to the development of new areas of land for agriculture and housing.

Adolescent↗