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Biomedical subjects

C Monteiro

Publications and source records attributed to C Monteiro.

30 records · Page 2Linked to original sources
PubMed1995

The allograft valve in heart transplantation and valve replacement. Genetic assessment of the origin of the cells by means of deoxyribonucleic acid profiles.

Assessment of the cellular origin of allograft valves is essential in comprehending their biologic behavior and in improving preparation methods. In this study we retrospectively analyzed 10 allografts obtained from patients who underwent valve replacement or heart transplantation. Histologic evaluation and deoxyribonucleic acid amplification by polymerase chain reaction technology with fluorescence labeled primers was performed on different parts of the valve leaflets. Automated analyses of the obtained amplimers showed in the heart transplantation group the presence of receptor cells interspersed with native donor cells in three cases. Preliminary results for the valve replacement group are inconclusive as yet.

Adult↗
PubMed1994

On the mechanisms of genotoxicity and metabolism of quercetin.

Quercetin has been the subject of numerous studies on its genetic toxicity and carcinogenicity. Despite its well-proven genetic damaging activity for various genetic end-points (reverse mutations, induction of SOS functions, induction of sister chromatid exchanges, chromosomal aberrations and micronuclei), the mechanisms of genetic damage by quercetin remain, by and large, unknown. The present study aims to further extend the observations on the possible active oxygen species mediated DNA-damaging activity of quercetin and the role of cytochrome P450-dependent metabolism on the genotoxicity of quercetin. The results reported in this work show that quercetin can produce the OH. radical, as assessed by deoxyribose degradation in the presence of Fe3+/EDTA (ethylenediaminetetraacetic acid), and that it induces strand breakage in isolated plasmidic DNA (pUC18). The data support the hypothesis that the production of OH. is mediated by H2O2. The results with genetically engineered V79 cells expressing rat cytochromes 1A1, 1A2 and 2B1 failed to demonstrate metabolism of quercetin, as indicated by the fact that neither an enhancement nor a decrease in the genotoxicity of quercetin was observed. Results obtained on the pH dependence of the induction of chromosomal aberrations by quercetin in V79 cells show that, as the pH value of the medium is increased to 8.0, there is a significant increase in the number of aberrant cells, as expected if oxygen radicals are responsible for the formation of chromosomal aberrations.

Animals↗
PubMed1993

Helicobacter pylori detection: a quality and cost analysis.

Histopathologic interpretation of hematoxylin and eosin (H&E)-stained endoscopic biopsies is a common method for identifying Helicobacter pylori. Few studies report the accuracy of this method, and none have compared costs of other diagnostic methods. In the clinical setting of a community hospital using standard diagnostic techniques, the purpose of this study were to determine 1) the comparative sensitivities and specificities of the H&E stain, the Warthin-Starry silver stain, the Giemsa stain, and the CLOtest; 2) the sensitivity and specificity of an "experienced" pathologist in identifying H. pylori by H&E stains, compared with a rotating pathology faculty; and 3) the time to diagnosis (turnaround time) and current patient charges for each diagnostic method. Bacterial identification by the silver stain (or a combination of other tests which were likely to compensate for false-positive and false-negative silver stains) were used as the diagnostic standard in evaluating 94 consecutive cases with the following results: The H&E stain interpreted by the rotating pathology staff was the least sensitive method and one of the least specific tests that were studied. The silver and Giemsa stains were equally sensitive in identifying H. pylori; the silver stain was more specific. The CLOtest was less sensitive than the silver and Giemsa stains, but was equally specific. CLOtest was similar in sensitivity to the H&E stain examined by the "experienced" pathologist, but was more specific. An experienced pathologist was significantly more sensitive than the rotating pathologists in evaluating H&E-stained slides. Therefore, if H&E stains are used to identify H. pylori, which is a common practice, it may be advantageous to use an experienced pathologist. The CLOtest was a simple, rapid, and cost effective substitute for H&E stains in the identification of H. pylori.

Biopsy↗
PubMed1993

The worldwide magnitude of protein-energy malnutrition: an overview from the WHO Global Database on Child Growth.

Using the WHO Global Database on Child Growth, which covers 87% of the total population of under-5-year-olds in developing countries, we describe the worldwide distribution of protein-energy malnutrition, based on nationally representative cross-sectional data gathered between 1980 and 1992 in 79 developing countries in Africa, Asia, Latin America, and Oceania. The findings confirm that more than a third of the world's children are affected. For all the indicators (wasting, stunting, and underweight) the most favourable situation--low or moderate prevalences--occurs in Latin America; in Asia most countries have high or very high prevalences; and in Africa a combination of both these circumstances is found. A total 80% of the children affected live in Asia--mainly in southern Asia--15% in Africa, and 5% in Latin America. Approximately, 43% of children (230 million) in developing countries are stunted. Efforts to accelerate significantly economic development will be unsuccessful until optimal child growth and development are ensured for the majority.

Africa↗
PubMed1992

Systemic lupus erythematosus in a child receiving long-term interferon therapy.

Systemic lupus erythematosus (SLE) developed in a 10 1/2-year-old white boy with juvenile laryngeal papillomatosis who had been treated with interferon alfa-n1 for 7 years. His age, gender, and fast recovery after discontinuation of interferon therapy and institution of appropriate treatment for SLE are compatible with a diagnosis of drug-induced SLE. Autoimmune disorders may occur as a complication of interferon therapy.

Autoimmune Diseases↗
PubMed1990

Tracheal agenesis.

Tracheal agenesis is a rare congenital anomaly. We report a case and review the cases previously reported. Clinical features that might indicate tracheal agenesis include antenatal polyhydramnios, severe respiratory distress, absence of an audible cry, failure to advance an endotracheal tube beyond the larynx, a palpable distal trachea, clinical improvement after esophageal intubation, and roentgenographic absence of a tracheal air column with an abnormal position of the carina. For immediate management of the affected infant, we recommend intubation of the esophagus with an endotracheal tube to provide an air passage, and determination of the level of the defect by careful use of contrast material and roentgenography. Infants having type I tracheal agenesis may benefit from immediate tracheostomy.

Bronchial Fistula↗
PubMed1990

Linkage of hereditary motor and sensory neuropathy type I to the pericentromeric region of chromosome 17.

Vance et al. have reported linkage of hereditary motor and sensory neuropathy type I (HMSN I) to the pericentromeric region of chromosome 17. We have studied eight families with HMSN I (also called the hypertrophic form of Charcot-Marie-Tooth disease) for linkage of the disease locus to polymorphic loci in the centromeric region of chromosome 17. Linkage has been confirmed for D17S58 (EW301) with a maximum lod score of 5.89 at theta = 0.08 and for D17S71 (pA10-41) with a maximum lod score of 3.22 at theta = 0.08. EW301 is on 17p, 5.5 centimorgans from the centromere. Two families, previously reported as being linked to the Duffy blood group locus on chromosome 1, were included in this study, and one now provides positive lod scores for chromosome 17 markers. There was no evidence of heterogeneity.

Charcot-Marie-Tooth Disease↗
PubMed1989

The frequency and origin of the sickle cell mutation in the district of Coruche/Portugal.

The frequency of the beta S mutation in the district of Coruche/Portugal is estimated to be about 4% from analysis of a group of 181 school children and their teachers in an area in which malaria has been endemic until recently. Several white Portuguese patients with sickle cell disease (six homozygous SS and one S beta degree thalassaemia) were found in a group of 309 further patients who were known and followed up by local medical practitioners. These patients had clinical and haematological features similar to patients of African origin, although their growth and sexual development appeared to be normal. The analysis of an array of polymorphic restriction sites within the beta S globin gene cluster (beta S haplotype) showed patterns that are known to occur in Africa. The frequencies of the three main African beta S haplotypes termed Senegal, Bantu, and Benin reflect the extent of Portuguese naval explorations. It is concluded that the sickle cell gene in Portugal has probably been imported from Africa and has been amplified in comparison with other genes characteristic for African races because of the selective advantage of AS heterozygotes in an area endemic for malaria.

Adolescent↗
PubMed1989

Oxidative stress in trisomy 21. A possible role in cataractogenesis.

Previous studies have suggested that free radicals and related species play a role in lens damage. The molecules involved may include proteins, lipids and DNA. Focal cortical changes and cortical liquefaction have been reported in patients with Down's syndrome over the age of 15 years. There is evidence supporting the hypothesis that trisomy 21 patients have an increase in free radical reactions and lipoperoxidation susceptibility. This could be due to an increase in the H2O2 generation catalysed by CuZn SOD although the activity of other gene products coded for on chromosome 21 cannot be excluded. Thiobarbituric acid reactive products were measured in human erythrocytes of nine DS patients and nine age-matched controls. There was a significant increase in the first group (21.0 +/- 2.3 nmol MDA/g Hb vs 16.4 +/- 2.9 nmol MDA/g Hb; p less than or equal to 0.01). In plasma, however, TBA products and antioxidant levels (ascorbic acid, tocopherol and uric acid) were not significantly different. Further studies should be carried out, namely through the use of more specific and sensitive methods, to assess the possible association between oxidative stress and cortical lens damage in DS patients.

Adolescent↗
PubMed1987

Superiority of antibody versus delayed hypersensitivity in clearance of HSV-1 from eye.

The contribution that antibody and delayed type hypersensitivity (DTH) make in promoting HSV-1 clearance from the infected cornea was investigated. Balb/c mice were immunized intravenously or subcutaneously with an attenuated strain of HSV-1 to generate hosts which were antibody-producing DTH-tolerant or antibody-producing DTH-responsive. Anti-mu serum treated mice were likewise sensitized intravenously or subcutaneously to obtain hosts which were antibody depressed-DTH tolerant or antibody-depressed DTH-responsive. Eight days after sensitization, these four sensitized groups and unsensitized controls were infected on scarified corneas with a stromal keratitis inducing strain of HSV-1, and the extent of virus replication was determined 1, 3, and 7 days later. Very different results were obtained depending upon the host's immune status. Virus proliferated extensively (greater than 3-4 logs) in the eyes of nonimmune mice and antibody-depressed DTH-tolerant hosts during the first 3 days after infection. In striking contrast, HSV-1 could not be detected even 24 hr post challenge in antibody-producing DTH-tolerant mice. In fact, such mice cleared virus from the eye as efficiently as immunologically intact hosts. However, in mice with the reverse immune status, ie antibody-depressed DTH-responsive, virus growth was clearly evident (greater than 2-3 logs) during days 1-3, and only thereafter did complete clearance occur. These results indicate that in the sensitized host antibody is both independent of and significantly more effective than DTH in promoting HSV-1 eradication from the infected eye.

Animals↗
PubMed1985

Resolution of HSV corneal infection in the absence of delayed-type hypersensitivity.

The role of delayed-type hypersensitivity (DTH) in the resolution of herpes simplex virus type 1 (HSV-1) ocular infection was examined. Infection of Balb/c mice on the sacrificed cornea with HSV-1 resulted in sensitization for DTH. This response, demonstrable by swelling of the ear following inoculation with ultraviolet-irradiated virus, was optimal 7 days postinfection. The reaction was immunologically specific and characterized histologically by a predominately mononuclear cell infiltrate. DTH responsiveness could be completely abrogated if the mice were inoculated intravenously with an attenuated strain of HSV-17 days before corneal infection. DTH-unresponsive mice were, nevertheless, resistant to corneal challenge with sublethal or lethal doses of HSV-1. Resistance was accompanied by a greater than 30-fold reduction in infectious virus in the eye 24 hr post challenge. A cellular infiltrate characteristic of a DTH response was not observed within the cornea during virus clearance. Tolerance was restricted to DTH, as antibodies to HSV antigens could be readily demonstrated 6-7 days after intravenous virus immunization. These antibodies may have contributed to the resistance observed. The results establish that neither a systemic nor local DTH response is required by the host to resist HSV-1 ocular infection.

Animals↗