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Biomedical subjects

G Ortega

Publications and source records attributed to G Ortega.

At least 55 records · Page 3Linked to original sources
PubMed1994

Differential effects of the pyrimido-pyrimidine derivatives, dipyridamole and mopidamol, on platelet and vascular cyclooxygenase activity.

The chronic administration of 10 mg/kg/day of dipyridamole to rats produced 33.7% inhibition of platelet aggregation induced with ADP and a 93% increase in 6-keto-prostaglandin F1 alpha (6-keto-PGF1 alpha) in vascular samples, versus saline-treated rats. Mopidamol, 8.3 mg/kg/day, caused 50.6% inhibition of ADP-induced platelet aggregation, 37.6% inhibition of aggregation induced with arachidonic acid, a 47.6% decrease in serum levels of thromboxane B2 and a 23.7% increase in the vascular production of 6-keto-PGF1 alpha, versus saline-treated rats. Dipyridamole showed a higher in vitro anti-aggregating effect in whole blood (IC50 6.6 microM) than in platelet-rich plasma (PRP) (IC50 210 microM), when ADP was used as inducer, and had no effect in the presence of arachidonic acid. Mopidamol exerted a similar effect in whole blood (IC50 3.7-20 microM, depending on the inducer) and PRP (IC50 11-17.3 microM), and showed a dose-dependent inhibition of platelet aggregation and thromboxane B2 synthesis induced with arachidonic acid (IC50 16.8-22.3 microM). Mopidamol also inhibited enzymatically induced lipid peroxidation) (IC50 89 +/- 5.9 mumol/L) and had no effect on free radical-induced lipid peroxidation. The dose-dependent increase in 6-keto-PGF1 alpha in vascular samples after incubation with dipyridamole showed a negative linear correlation with inhibition of lipid peroxidation (r2 = 0.77). It is concluded that the phosphodiesterase inhibitors, dipyridamole and mopidamol, interfere in a different manner with platelet function. It seems that mopidamol may also exert a selective effect on platelet thromboxane synthesis.

Animals↗
PubMed1994

Differences in the lymphoproliferative pattern to Leishmania mexicana antigens recognized by immunized and infected mice.

Immunity to leishmanial infection depends primarily on the activities initiated by T lymphocytes which have been sensitized to a diverse pool of parasitic antigens. In this study, the pattern of the lymphoproliferative responses of lymph node and spleen cells isolated from BALB/c and C57BL/6 mice previously infected with Leishmania mexicana was heterogeneous. However, we observed more pronounced responses to antigen fractions with molecular masses of 63 and 10-15 kDa, based on T cell immunoblotting. Responses were stronger and more persistent in the intermediate resistant C57BL/6 strain, as compared to the more evanescent response in the highly susceptible BALB/c mice. Similar responses in terms of immunodominant fractions were also consistently seen in total and T lymphocytes isolated from BALB/c mice which had been immunized with a soluble extract of Leishmania mexicana. These results are discussed in terms of general requirements for an effective vaccine against human leishmaniasis.

Animals↗
PubMed1993

Wheel running raises body temperature and changes the daily cycle in golden hamsters.

The purpose of this study was to characterize the influence of wheel-running activity on temperature circadian rhythm in golden hamsters. Amplitude of body temperature rhythm was significantly higher in animals that had access to the running wheel. Qualitatively, wheel running resulted in squaring of temperature rhythm waveform, a phenomenon that was independent of ambient illumination. When the hamsters had access to an immobilized wheel, the effect on temperature was no longer observed. Fast Fourier Transformation after subtracting 24-h sine waveforms (to rule out harmonics of the principal frequency), indicated distinct secondary components of the rhythms, i.e., a 12-h component in animals that had access to the wheels and an 8-h component in animals that did not. The rise in body temperature could be dissociated from the start of the activity period, body temperature augmenting before the time of light-dark transition, while activity increased about 12 min later. On the first night after presentation of an estrous female, the temperature cycle in male hamsters that did not access to the wheels was similar to that found in animals running on the wheels; the effect was no longer observed in subsequent nights. The results contribute to the view that the spontaneous locomotor activity in hamsters has a significant effect on temperature cycle.

Animals↗
PubMed1992

Inhibition of ferrous-induced lipid peroxidation by pyrimido-pyrimidine derivatives in human liver membranes.

The effects of pyrimido-pyrimidine derivatives (dipyridamole, RA-642, and RA-233) on lipid peroxidation, using d-alpha-tocopherol as standard, were studied in enriched membrane fractions from human and rat hepatocytes. Equimolar concentrations of ferrous sulfate and ascorbic acid were used to induce lipid peroxidation. The amount of peroxidized lipids observed in membrane fractions from human liver was smaller than in those from rat liver. In both species, however, pyrimido-pyrimidine derivatives, except for RA-233 in rat liver, inhibited lipid peroxidation dose-dependently in the following sequence: RA-642 greater than dipyridamole greater than d-alpha-tocopherol RA-233.

Animals↗
PubMed1992

Effect of zeitgeber intensity reduction on a simulated dual-oscillator human circadian system: classical and dynamic analysis.

The two-oscillator model of human circadian rhythmicity was analyzed when a zeitgeber relative intensity of 1, 0.5, or 0.1 was introduced into the equations. Fourier analysis was compared with dynamic analysis such as attractor reconstruction or Liapunov exponent calculation. After a 50 or 90% reduction in zeitgeber intensity, the dynamics of the system became equivalent and differed significantly from those of a system with maximal zeitgeber intensity. When 10% aleatory noise was added to the data, the analysis was still applicable, and the results obtained were essentially the same as in the absence of noise. Dynamic analysis could thus provide a distinct classification for periodic data, based on the type of analysis.

Biometry↗
PubMed1992

[Characterization of Paracoccidioides brasiliensis antigens. Serological immunodiagnosis using western blotting].

The electrophoretic characterization on SDS-PAGE gels of Paracoccidioides brasiliensis antigens, strains 2511 and 6688; and the additional use of immunoblotting has permitted in this study to identify the immunogenic, sensitive and specific antigen fractions for the diagnosis of Paracoccidioidomycosis. The antigenic preparations showed differences depending on the morphologic form of the fungus and the method utilized. The procedure revealed heterogeneity in the humoral immune response of the patients studied and permitted us to establish indices of activity of Paracoccidioidomycosis by the sequential analysis of sera obtained during different stages of the disease. The high sensitivity of this method makes it useful as an additional technique for the serologic immunodiagnosis of Paracoccidioidomycosis.

Antibodies, Fungal↗
PubMed1992

[Carotenodermia].

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Adolescent↗
PubMed1992

[Non-specific digestive ulcers and Behçet's disease].

We present a 56-year-old patient with episodes of recurrent abdominal pain and constitutional syndrome, whose evolution was complicated by mucous ulcers in mouth, esophagus, anus and ileocecal valve, as well as occasional aphthae in scrotum. All these clinical signs are compatible with a Behçet's disease with relevant digestive manifestations.

Abdominal Pain↗
PubMed1992

[Treatment of arterial hypertension with captopril in lupus nephropathy].

We present a non-controlled prospective study of 10 hypertensive patients with systemic erythematous lupus and nephropathy, treated with captopril exclusively or combined with other drugs, in order to assess its effectivity and potential side effects. Four of these 10 patients had mild hypertension; 3, moderate hypertension and 3, severe hypertension. In 5 of them, arterial pressures was controlled with just captopril; in other 3, we added furosemide and in one patient, we added furosemide and nifedipine. In one case, hypertension was not controlled. Renal function remained stable and proteinuria improved in six patients. Three patients presented reversible agranulocytosis, during or immediately after treatment. One of them was treated two years after with enalapril, without observing hematologic recurrence. We conclude that captopril is useful in treating arterial hypertension associated to lupous nephropathy, but frequent leukocyte counting controls must be done during the first months.

Adolescent↗