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Biomedical subjects

M A Fernandez

Publications and source records attributed to M A Fernandez.

At least 55 records · Page 3Linked to original sources
PubMed1987

Retinal lipid peroxidation in experimental uveitis.

Lewis rats with retinal S-antigen-induced uveitis were treated with the enzymatic antioxidants superoxide dismutase and catalase or with the hydroxyl radical scavenger dimethyl thiourea for one week. The enucleated eyes of these animals and of normal saline-treated control rats were studied for the presence of lipid peroxidation products in the retina; In addition, choroidal thickness was measured by morphometric analysis to determine the severity of choroidal inflammation. Control animals showed severe chorioretinal inflammation and presence of lipid peroxidation products. Intraocular inflammation was less severe and formation of conjugated dienes and malonaldehyde was significantly inhibited in animals treated with the enzyme antioxidants or dimethyl thiourea. These results suggest that free radicals generated during intraocular inflammation can lead to retinal damage by peroxidation of its lipid cell membranes.

Animals↗
PubMed1987

Immunohistochemical localization of catalase in ocular tissue.

Localization of catalase in rat and bovine ocular tissues was investigated by an immunohistochemical method. Antisera to purified catalase was raised in a rabbit. Purity of catalase was determined by gel electrophoresis and specificity of the antibody was tested by immunoblot. The immunohistochemical method revealed the presence of catalase predominantly in epithelial and endothelial structures of the eye and in the retina, except in the outer segments. Catalase was found in abundance in those structures that are frequently exposed to oxygen metabolites under physiologic conditions and in such pathologic states as intraocular inflammations. These findings thus suggest that catalase, along with other antioxidant enzymes, may offer protection against the damaging effects of hydrogen peroxide.

Animals↗
PubMed1987

Role of oxygen radicals in experimental allergic uveitis.

The experimental autoimmune disease elicited by a large dose of retinal S antigen in guinea pigs is characterized by massive necrotizing uveitis and retinitis. Treatment of these animals with the antioxidants superoxide dismutase, catalase, and sodium benzoate resulted in marked reduction of uveal inflammation. The attenuated inflammation was characterized by a relatively well-preserved retina and retinal pigment epithelium along with a reduction of subretinal exudate and vitreous inflammation. These findings suggest that reactive oxygen metabolites may play a role in the destruction of ocular tissue and amplification of the inflammatory process in experimental uveitis.

Animals↗
PubMed1986

Effect of iron chelation on severity of ocular inflammation in an animal model.

Metabolites of oxygen-free radicals generated by polymorphonuclear leukocytes and macrophages are believed to inflict the initial tissue damage in acute inflammations. Of the various oxygen products, hydroxyl radicals are known to be potent toxic agents, and their generation depends largely on the presence of free iron. Treatment of experimental uveitis in Lewis rats with an iron chelator, deferoxamine mesylate, resulted in marked reduction in choroidal inflammation and suppression of retinal damage. These findings suggest that in experimental uveitis the severity of ocular inflammation and tissue damage may be mediated by the iron-catalyzed generation of hydroxyl radicals, and deferoxamine may thus serve as an anti-inflammatory agent.

Animals↗
PubMed1986

Activation and deactivation of the membrane-bound hydrogenase from Desulfovibrio desulfuricans, Norway strain.

The hydrogenase from D. desulfuricans, when isolated in air, had a low activity in the hydrogen-methyl viologen reductase assay, and no activity in the hydrogen-methylene blue reductase assay. The activity increased markedly during incubation under hydrogen. This process is interpreted in terms of conversion of the enzyme from a relatively inactive Unready state to the Active state. Oxidation by dichloro-indophenol caused conversion to a state in which the hydrogen-uptake activity to methyl viologen was preserved, but hydrogen-methylene blue activity was not. This form is termed the Ready state. This behaviour resembles that of the hydrogenase of Desulfovibrio gigas and thus may be a widespread property of this class of hydrogenases. The electron-spin-resonance spectra of the D. desulfuricans enzyme showed the presence of [3Fe-xS] and [4Fe-4S] clusters. Spectra were also observed in the various states of activation of the enzyme. In these respects, the hydrogenase of D. desulfuricans resembles that from D. gigas, although the latter may have an additional iron-sulphur cluster.

2,6-Dichloroindophenol↗
PubMed1986

Antiphlogistic effect of catalase on experimental phacoanaphylactic endophthalmitis.

Oxygen-derived free radicals generated by polymorphonuclear leukocytes have recently been implicated as important pathogenic mediators of tissue damage in immune complex-mediated acute inflammatory reactions. In order to study the role of oxygen radicals in experimentally induced phacoanaphylactic endophthalmitis, rats were immunized with soluble bovine lens protein and, following surgical disruption of the anterior lens capsule, subjected to treatment with catalase. Our data show that phacoanaphylactic endophthalmitis, as determined morphologically and by measurements of retinal edema, choroidal inflammation, retinal hemorrhage and necrotizing vasculitis, is greatly diminished in catalase-treated animals. This protective effect of catalase indicates that hydrogen peroxide (H2O2) and/or conversion products of H2O2 (e.g., hydroxyl radical, hypochlorous acid) may play an important role in the development of experimental phacoanaphylactic endophthalmitis.

Animals↗
PubMed1983

Effect of zinc deficiency on plasma glutathione in the rat.

The objective of this study was to determine the effect of zinc status on plasma glutathione concentration. Immature male rats were fed a low-zinc (less than 1 ppm) diet based on soybean protein. Pair-fed and ad libitum-fed controls consumed a similar diet supplemented with zinc (100 ppm). The plasma concentration of total glutathione (GSH plus GSSG), as determined by the glutathione reductase recycling method of Tietze, decreased in all groups when plasma was allowed to stand in air at room temperature. At 5 min approximately 90% of the total glutathione was present as GSH and the measurable concentration of GSH decreased logarithmically during 60 min. Less than one-half of the loss was accounted for by conversion to GSSG; the nature of the remaining loss is unknown. The plasma of rats fed the zinc-deficient diet for 2 weeks contained less total glutathione than that of ad libitum-fed controls. There was no difference between zinc-deficient rats and pair-fed controls.

Animals↗
PubMed1982

Evaluation of the soluble fibrin monomer complexes and other coagulation parameters in obstetric patients.

The soluble fibrin monomer complexes (SFMC) in 154 obstetric patients with possible disseminated intravascular coagulation (DIC) were evaluated in SDS polyacrylamide gel electrophoresis (PAGE) after precipitation with B-alanine. Other coagulation tests were performed on these patients. The patients were classified into three groups: A) patients with a clinical history of DIC (6 cases); B) patients with only the analytical alterations of DIC (35 cases); and C) patients who showed pathological obstetric diagnoses but without a clinical nor analytical history of DIC (113 cases). In the three groups, well-defined bands of less electrophoretic mobility than fibrinogen were obtained. A significant increase in the second electrophoretic band was found in group A (5.1 per cent) when compared to group C (0.5 per cent). The second electrophoretic band appeared in greater proportion in the group of patients with an unfavorable clinical evolution.

Abruptio Placentae↗
PubMed1982

Elevated lipid peroxide levels in platelets of chronic ischemic heart disease patients.

A significantly higher platelet malondialdehyde-like material (MDA--LM) content after physical and N-ethylmaleimide (NEM) stimulation is found in chronic ischemic heart disease (CHD) patients when compared to the control group. In subjects under aspirin treatment "in vivo" (1 gr/day) no difference is found between CHD and control group. It is suggested that the enhanced amount of lipid peroxides in CHD platelets is produced by a cyclooxygenase-dependent mechanism. This enhanced platelet lipid peroxide production in CHD may be another platelet-dependent risk factor for atherosclerosis in these patients.

Anticoagulants↗
PubMed1982

Oncocytoma of the lung.

This report describes the clinical, anatomical, histologic and ultrastructural features of a bronchial oncocytoma. Histologically the oncocytes have granular eosinophilic cytoplasm. Ultrastructurally this corresponds to mitochondrial hyperplasia. Because cytoplasmic eosinophilia may be due to an abundance of cytoplasmic organelles other than mitochondria, it is emphasized that electron-microscopic study is an essential component in the diagnosis of oncocytomas.

Adult↗
PubMedDate not supplied

Second trimester low-lying placenta and in-vitro fertilization? Exclude vasa previa.

We report the prenatal diagnosis of vasa previa using transvaginal sonography and color Doppler. This case supports the previously reported association of vasa previa with second trimester low-lying placentas and in-vitro fertilization. Sonographic examination for vasa previa should be considered in pregnancies with low-lying placentas and those resulting from in-vitro fertilization.

Adult↗
PubMedDate not supplied

Mapping of intrinsic bent DNA sites in the upstream region of DNA puff BhC4-1 amplified gene.

We have identified bent DNA sites in the distal and proximal DNA puff BhC4-1 amplified gene promoter region of Bradysia hygida. The 2D modeling of the 3D DNA path and the ENDS ratio values calculated in this promoter region resulted in the identification of ten pronounced bent sites named BhC4B - 9 to + 1. The 1847 bp fragment (- 3697 to - 1850) in relation to the transcription start site shows multiple bending sites, BhC4B - 9 to BhC4B - 4, with periodicity approximately 300 bp. The analysis of the other identified bent region, starting at position - 957, reveals that the BhC4B + 1 bent site colocalizes with the putative BhC4-1 minimal promoter. The sequence analysis of bent site BhC4B - 4 shows a distribution of dA*dT at approximately 10 bp intervals between the middle of each tract, but intervals with more than one turn, approximately 20 bp, two helix turns, were detected in the other bent sites described here. The bent sites BhC4B - 6 and BhC4B - 4, contain two consensus sequences, with 60 bp each. The apparent molecular weight of fragments in the BhC4-1 promoter region were estimated in agarose gels and compared with the data obtained in polyacrylamide gels without and with ethidium bromide. The mobility reduction ratios (R-values) were determined, and a high R-value, 1.80, for a 1215 bp fragment in the distal promoter region and a 1.23 significant R-value for a 662 bp fragment in the proximal segment were found. To further analyze the predicted bent DNA sites in these fragments, the 2D trajectories of the 3D DNA path and other parameters, AT percentage, roll angle, ENDS ratio and DeltaG, were determined. The role of these bent sites in the BhC4-1 transcription regulation is discussed.

Animals↗
PubMedDate not supplied

Role of free radicals in uveitis.

In acute inflammation, the tissue damage is generally mediated through polymorphonuclear leukocytes and macrophages. Recent studies on the mechanism of this leukocyte-mediated cytolysis have demonstrated that these cells, on stimulation, release a variety of reactive products. These metabolic products consist of superoxide and hydrogen peroxide, which in turn can form highly reactive species such as hydroxyl radicals. It is believed that these oxygen products play an important role in the tissue damage that occurs in inflammations such as uveitis. The ocular structures contain various antioxidant enzymes that normally protect against free radical mediated injury. In experimental animal models of uveitis, it has been shown that antioxidants and free radical scavengers can function as antiinflammatory agents and can protect the eye from inflammation-mediated tissue damage.

Animals↗