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Biomedical subjects

A Osuna

Publications and source records attributed to A Osuna.

At least 127 records · Page 7Linked to original sources
PubMed1985

[Effect of proteolytic enzymes on the penetration of Trypanosoma cruzi in peritoneal macrophages of mice].

The present study deals on the modifications produced by three proteolytic enzymes in the interiorization of cultured metacyclic forms of Trypanosoma cruzi in peritoneal macrophages of non-stimulated mice. The proteolytic enzymes used were trypsin, papain and collagenase. Pretreatment of metacyclic forms or macrophages with the enzymes resulted in lower penetration ratios with respect to controls. On the other hand, percentages of parasitization were maintained throughout the periods of time assayed.

Animals↗
PubMed1984

Purification of metacyclic forms of Trypanosoma cruzi by Percoll discontinuous gradient centrifugation.

A method for the purification of metacyclic forms of Trypanosoma cruzi has been developed. Metacyclic forms obtained in modified Grace medium were separated from the epimastigote forms by Percoll discontinuous density gradient centrifugation. Four different osmotic pressures were applied: 160 +/- 10, 260 +/- 10, 310 +/- 10 and 510 +/- 10 mosmol/kg H2O. At 160 mosmol/kg H2O, 100% of the metacyclic forms with a 21.3% yield were found in the interphase 1.120/1.125 g/ml, while 92.7% of the metacyclic forms with a 73.7% yield were found in the interphase 1.115/1.120 g/ml. At 310 mosmol/kg H2O, 100% of the metacyclic forms in the interphase 1.135/1.140 g/ml with a 36.8% yield were obtained. Metacyclic forms purified in this way do not show alterations in their capacity to infect cultures of HeLa cells.

Animals↗
PubMed1977

Regular G21-trisomy in 3 sibs from mother with trisomy 21 mosaicism.

This paper describes a family with 3 affected sibs with regular trisomy 21 Down syndrome. The condition seems to be transmitted from a phenotypically normal mother in whom G-trisomy mosaicism was identified. Giemsa banding depicted trisomy 21 mosaicism in cells from the mother. Chromosomes from the children showed a trisomy 21 in all the cells analysed.

Adolescent↗
PubMedDate not supplied

Studies on the interaction between antitrypanosome cis-DDP analogs with DNA.

The nature of the conformational changes produced in DNA by cis-DDP analogs has been studied by physiochemical techniques. The UV spectra showed that the DNA undergoes bathochromic shifts accompanied by hyperchromic effects in reaction with specific analogs (cis-Pt(DDH) (mucobromic)2, cis-Pt(tranilcypromine)2Cl2 and cis-Pt(DDH) Cl2), while a different series of analogs (cis-Pt(DDH) (metafluorobenzoic)2 and cis-Pt(pentamidine)Cl2) induce a significative decrease in the absorbance at 258 nm. Moreover one of these analogs (cis-Pt(pentamidine)Cl2) causes strong stabilization of the double helix to heat denaturation. The CD spectra indicate moreover that cis-Pt(pentamidine)Cl2 modifies the secondary structure of the DNA in a significant way with an increase of the positive band and a decrease of the ellipticity of the negative band. The antitrypanosome activity of cis-Pt(pentamidine)Cl2 is probably due to inhibition of the intracellular parasites division in parasitized cells.

Animals↗
PubMedDate not supplied

Ultrastructural investigation of human sperm using atomic force microscopy.

Ultrastructural investigation of human sperm in its natural environment (without fixation, dehydration, embedding, sectioning, etc.) was carried out by using atomic force microscope (AFM) in its tapping mode. This technique permits the examination of fine structural details of undamaged sperm and its topography with precision. Moreover, it allows 3D reconstruction of images and enhances the contrast to resolve details such as mitochondria that surround the axoneme at the sperm middle piece. An organized structure has been found in the flageller axoneme region. Ultrastructure also reveals folding and details of the depression of the membrane that cannot be examined with conventional techniques.

Humans↗
PubMedDate not supplied

The different behavior of diphtheria toxin, modeccin and ricin in HeLa cells infected with Trypanosoma cruzi.

We have studied the action of diphtheria toxin, modeccin and ricin on HeLa cells infected by Trypanosoma cruzi. Parasitized HeLa cells were resistant to diphtheria toxin and modeccin, whereas non-parasitized cells from the same cultures and control cultures showed cytopathological alterations. Protein synthesis, assayed by the incorporation of labelled methionine, diminished in toxin-treated control cultures but remained unaltered in the infected ones, compared to synthesis by untreated infected cells. Ricin, on the other hand, is a toxin that enters the cytoplasm by endocytosis. It has greater cytopathological effects in parasitized cells than in non-parasitized ones from the same cultures or uninfected control cells. Protein synthesis was inhibited in infected cultures treated with ricin.

Animals↗
PubMedDate not supplied

Adenylyl cyclase and G-proteins in Phytomonas.

Phytomonas sp. membranes have an adenylyl cyclase activity which is greater in the presence of Mn2+ than with Mg2+. The Mg2+ and Mn2+ activity ratio varies from one membrane preparation to another, suggesting that the adenylyl cyclase has a variable activation state. A[35S]GTP-gamma-S-binding activity with a Kd of 171 nM was detected in Phytomonas membranes. Incubation of these membranes with activated cholera or pertussis toxin and [adenylate 23P]NAD+ led to incorporation of radioactivity into bands of about 40-44 kDa. Crude membranes were electrophoresed on SDS-polyacrylamide gels and analyzed, by Western blotting, with the 9188 anti-alpha[s] antibody and the AS/7 antibody (anti-alpha[i], anti-alpha[i1], and anti-alpha[i2]. These procedures resulted in the identification of polypeptides of approximately 40-44 kDa. Phytomonas adenylyl cyclase could be activated by treatment of membrane preparations with cholera toxin, in the presence of NAD+, while similar treatment with pertussis toxin did not affect this enzyme activity. These studies indicate that in Phytomonas, adenylyl cyclase activity is coupled to an unknown receptor entity through G alpha[s] proteins.

Adenosine Diphosphate↗
PubMedDate not supplied

Modulatory role of endothelium-derived relaxing factors on the response to vasoconstrictors and flow-pressure curve in the isolated perfused rat kidney.

The aim of this study was to compare the effects of the blockade of nitric oxide (NO) and of endothelium-derived hyperpolarizing factor (EDHF) on the response to vasoconstrictors (VC) and on the flow-pressure curve in the isolated perfused rat kidney. To this end, dose-response curves to phenylephrine and BaCl2 were studied in the renal vasculature under basal conditions and after the infusion of N(omega)-nitro-L-arginine methyl ester (L-NAME) and tetraethylammonium (TEA) in endothelium-intact and endothelium-denuded (CHAPS-treated) preparations. In another experiment, renal flow-pressure curves were obtained under basal conditions and after the infusion of L-NAME or TEA. The flow-pressure curve was obtained by increasing renal perfusion flow (RPF) from 2.5 to 15 ml/min/g kidney weight (KW) over the basal level (5 ml/min/g KW). L-NAME or TEA produced a leftward shift of the dose-response curves of both VC, and the simultaneous administration of L-NAME and TEA produced a greater shift to the left in the pressor response curves. CHAPS treatment produced a leftward shift of the dose-response curves of both VC, and the dose-response curves were not significantly modified by the infusion of L-NAME or TEA. L-NAME markedly shifted the flow-pressure curve upward, especially at higher levels of RPF. However, the administration of TEA, perfusate solution (Tyrode) or D-NAME did not significantly change the flow-pressure curve. These results suggest that NO is released in response to VC as well as to increased perfusion flow in the isolated renal vascular bed. However, EDHF release seems to be stimulated by VC but not by increased perfusion flow.

Animals↗
PubMedDate not supplied

Cryptorchidism: treatment with human chorionic gonadotropin--a Venezuelan experience.

The study comprised 323 cryptorchidic boys, between 6 months and 14 years of age (mean age 5.68 years) with 440 maldescended testes. Testicular position was graded as inguinal low or prescrotal (I), inguinal middle (II), inguinal high (III), and abdominal testes (IV). Boys before 4 years of age received human chorionic gonadotropin (hCG) as intramuscular injections (I.M.), 500 IU twice a week for 5 weeks; and boys 4 or more years of age received hCG (IM), 1000 IU twice a week for 5 weeks. The objectives of this study were to evaluate the response of maldescended testes to treatment with hCG, and to investigate possible associations between the patients' ages and position of the testes with the response to hCG. Out of the 440 maldescended testes, 329 were in an inguinal location (75%) and 111 were abdominally located (25%). The overall response to hCG was 40%, and the inguinal testes response was 49%, with the highest success rates (72%) for the prescrotal testes. A positive correlation was found (p < .0001) between the rate of success and the testicular position. There was no association between the hCG response and the age at which treatment was initiated.

Adolescent↗
PubMedDate not supplied

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History, Modern 1601-↗