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Biomedical subjects

A Osuna

Publications and source records attributed to A Osuna.

At least 109 records · Page 6Linked to original sources
PubMed1988

New antiparasitic agents. III. Comparison between trypanocidal activities of some acridine derivatives against Trypanosoma cruzi in vitro.

Some acridine compounds referred to as 9-imino, 9-oxo and 9-thio derivatives were screened for activity against Trypanosoma cruzi in vitro. The results are discussed here with reference to the structure of the compounds tested. Attempts to elucidate the mode of action of active acridines are also included. The most active compounds that were tested were 9-thioacridanones and 9-thio-1,2,3,4-tetrahydroacridanones Added to this, the dialkylaminoalkylthio group seems to be the most convenient molecular moiety for trypanocidal activity in the 9-substituted acridine series.

Acridines↗
PubMed1988

Activity of rhodium(III) complexes against Trypanosoma cruzi.

In the present paper the antiprotozoan activity of several rhodium(III) complexes was studied by analysis of the [3H]-thymidine, [3H]-uridine and [3H]-leucine uptake occurring in epimastigotes of Trypanosoma cruzi in the presence of the drug as well as their effect on the viability and motility of infective forms. It has been found that the complexes do not interact with native DNA but that some of them inhibit both the precursor uptake and the viability of metacyclic forms. It seems that the mode of action on the epimastigotes should be different from that observed on metacyclic forms.

Animals↗
PubMed1988

[Photomaniac behavior and schizophrenia].

Two patients with a chronic residual schizophrenic disorder, according to DSM-III-R, showed a marked resistance to intensive light, manifested through a lack of intolerance and pain when looking at the Sun directly. Light suppresses melatonin secretion in humans, and the melatonin rhythm reflects the subject's light/darkness exposition. A photomaniac character of such a behavior (or phenomena that could favor it) recalls its opposite--the photophobic behavior as described in some cases of depression, and could cause a different profile of exposition to the light. Knowing about such phenomena--such though they lack every explanation for the time being--could be useful--from a methodology point of view, as well as heuristically valuable--during the study of photosensitive neuroendocrine processes in patients who evidence such phenomena.

Humans↗
PubMed1987

Differential behaviour of glucose 6-phosphate dehydrogenase in two morphological forms of Trypanosoma cruzi.

1. Glucose 6-phosphate dehydrogenase activity (EC 1.1.1.49) of two morphological forms of Trypanosoma cruzi, epimastigotes and metacyclics, are reported. 2. The kinetic behaviour and some of the kinetic parameters of the enzyme in both forms were studied. The enzymes showed a simple Michaelis-Menten kinetic. 3. The activity in epimastigote forms was alway higher than the metacyclic ones. At subsaturating concentrations of substrate was almost 10-fold higher, whereas at saturating concentrations was about 2-fold higher. 4. In epimastigote forms the specific activity and Km values, at pH 7.5 and 37 degrees C, was found to be 142 mUnits x mg-1 of protein and 0.23 mM, respectively. 5. In the same conditions, the specific activity and Km values in metacyclic forms was 75 mUnits x mg-1 of protein and 1.06 mM, respectively. 6. A possible role in the carbohydrate metabolism of glucose 6-phosphate dehydrogenase in both forms of Trypanosoma cruzi is discussed.

Ammonia↗
PubMed1987

Antitrypanosomal action of cis-diamminedichloroplatinum (II) analogs.

The present report deals with the alterations produced by cis-diamminedichloroplatinum (II) (DDP), and 2 of its analogs: cis-Pt(II)(tranylcypromine)2Cl2 and cis-Pt(II)(benzothiazole)2Cl2 in cultured epimastigote forms of Trypanosoma cruzi. Studies have been performed at the ultrastructural level and the inhibitory effect of these complexes on macromolecule synthesis, evaluated by 3H-thymidine, 3H-uridine, and 3H-leucine incorporation, has been investigated. DDP at concentrations of 50 and 100 micrograms/ml does not inhibit significantly the incorporation of radioactive precursors, but a clear decrease was observed with the 2 analogs. Eight hours of treatment at a concentration of 10 micrograms/ml rendered in all 3 cases an increase in autophagic vacuoles and lipids as well as an abnormal condensation of the nucleus chromatin.

Animals↗
PubMed1987

Mode of action of intercalating drug, cis-Pt(II)(DDH)Cl2, cis-Pt(II)(DDH) (metafluorobenzoic)2, and cis-Pt(II)(DDH)(mucubromic)2, on Trypanosoma cruzi.

The trypanocidal activity of three new compounds derived of the antineoplastic drug cis-diamminodichloroplatinum(II) (DDP) has been studied over epimastigote forms of Trypanosoma cruzi. The electron microscopy indicated that, in the treated animals, the nuclear chromatin is distributed in the nucleus in a lax form and that the number of lipidic vacuoles increases largely. This action is more significant when cis-Pt(II)1,2-diaminocyclohexane is used. In addition this compound causes a destabilization of the DNA double helix with a decrease of melting temperature. The three compounds inhibit the incorporation of leucine, uridine and thymidine, although the thymidine uptake is the most significantly affected.

Animals↗
PubMed1986

Study of an amoeboflagellate isolated from the nasal mucosa of man.

This paper examines the biology, morphology, and pathogenicity for mice of an amoeboflagellate isolated from human nasal mucosa. The biological and morphological relationships of this isolate with the amoebae (Lobosea) and the true slime molds (Eumycetoza) are discussed though the taxonomic affinities of the organism have not been determined.

Amoeba↗
PubMed1986

Evaluation of the toxicity of Rh(III) and Pt(II) complexes against Trypanosoma cruzi culture forms.

In the present study the activity of 15 complexes of Rh(III) and 19 of Pt(II) against Trypanosoma cruzi epimastigote forms was investigated. The results obtained show that complexes of Rh(III) with the highest antitumoural activity also appear to be more effective against cultured epimastigotes. Thus, complexes [Rh(L)4X2]+X- where L is a derivative of thiazole present high activity against the parasite, and were even more active when Cl- (X) was present in their structure. Complexes cis-Pt(L)m(X)n that present 1,2-diamminecyclohexane (DDH) in their molecule, e.g. cis-Pt(DDH)Cl2 and cis-Pt(DDH)(metafluorobenzoic)2 of high and moderate antitumoural activity, respectively, have shown greater effectiveness than cis-Pt(NH3)2Cl2 (DDP). The effect produced by cis-Pt(pentamidine)Cl2 complex, obtained in order to enforce the action of pentamidine, was considerably high. On the other hand, no positive correlation can be established between the antitumour effects of the Pt(II) complexes and its antitrypanosomic activity.

Animals↗
PubMed1985

Effect of poly-L-lysine and neuraminidase on the infectivity of Trypanosoma cruzi in cultured HeLa cells.

The percentage of parasitisation and index of adherence of Trypanosoma cruzi has been studied when host HeLa cells or metacyclic forms were pretreated with neuraminidase or with poly-L-lysine. The percentage of parasitisation was significatively reduced (P less than or equal to 0.001) when cells were pretreated with poly-L-lysine while pretreatment with neuraminidase caused no apparent effects. On the other hand, the adherence of the metacyclic forms pretreated with poly-L-lysine or neuraminidase was significantly higher than that of the control group.

Adhesiveness↗
PubMed1985

Isolation and purification of amastigotes of Trypanosoma cruzi from cultured vero cells.

A method is described for the isolation and purification of the intracellular amastigotes of Trypanosoma cruzi from cultured Vero cells. Host cells were infected with metacyclic forms obtained in Grace's medium. Six days after infection, the cells wer subjected to treatment with trypsin to obtain the intracellular forms. The parasites were collected and purified by Percoll discontinuous gradient centrifugation.

Animals↗