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Biomedical subjects

M Bravo

Publications and source records attributed to M Bravo.

At least 91 records · Page 5Linked to original sources
PubMed1991

[Anticardiolipin antibodies in systemic lupus erythematosus: prevalence and clinical associations].

Anti-cardiolipin antibodies have been recently described in patients with systemic lupus erythematosus and other autoimmune disorders. Venous and arterial thrombosis, thrombocytopenia and recurrent abortion have been associated to the presence of these antibodies. Among 161 patients with systemic lupus we found 66% with anticardiolipin antibodies, mostly IgG type. Thrombosis and thrombocytopenia were more frequent in these patients (p < 0.05), especially among those with high titers. No association was found with central nervous system involvement, recurrent abortion, antinuclear or anti-DNA antibodies nor positivity for VDRL. These results support the frequent presence of anti-cardiolipin antibodies in patients with systemic lupus and their association to thrombosis and thrombocytopenia.

Adolescent↗
PubMed1991

[Utilization of health services in Puerto Rico of persons with mental disorders].

As part of a major study on the prevalence of mental disorders in Puerto Rico, this paper describes the mental health care utilization patterns of persons with a Diagnostic Interview Schedule (DIS) disorder within the last year. The main findings of this analysis show that a) there is a high rate of health service utilization, b) the public sector is the main provider of services c) persons with a DIS disorder use more the non psychiatric physician d) those with alcohol abuse and/or dependence tend to use more the services of general practitioners while schizophrenics, somatizers and those with cognitive impairment use more the services of mental health specialists. The use of other resources such as clergy or spiritualists do not substitute the use of health services.

Adolescent↗
PubMed1990

The psychological sequelae of disaster stress prospectively and retrospectively evaluated.

Aimed to document the psychological sequelae of a disaster in the adult (17-68 years) population of the Caribbean island of Puerto Rico, by surveying 912 persons (including 375 previously interviewed) with a Spanish version of the Diagnostic Interview Schedule. A rigorous methodology, which included both retrospective and prospective designs, was used, enabled by the occurrence of a catastrophic disaster only a year after a comprehensive survey was completed. Framed in a stress theoretical perspective, disaster effects for new depressive, somatic, and posttraumatic stress symptoms were identified, even after adjusting for demographic and methodologic factors. All the effects, however, were relatively small, suggesting that most disaster victims were rather resilient to the development of new psychological symptoms. Comparison of results with previous findings and its implications for both disaster and stress research are discussed, as well as the role of community psychologists in disaster action.

Adaptation, Psychological↗
PubMed1990

Preattentive vision and perceptual groups.

Recent evidence suggests that preattentive processing may not be limited to the analysis of simple stimulus features as previously suggested. To explore this idea a visual search task was used to test whether the shapes of several perceptual groups can be processed in parallel. Textured displays that give rise to strong perceptual grouping were used to create figures on a background. Search times for a target figure distinguished by a unique shape were found to be independent of the number of distractor figures in the display. This result indicates that perceptual groups may be processed in parallel and suggests an expanded role for preattentive processing in vision.

Adult↗
PubMed1990

Children of parents with psychiatric disorder in the community.

The relationship between parental psychopathology and risk for maladjustment in the offspring was investigated in a community sample. The children of 130 parents who met criteria for 12 DIS/DSM-III disorders were compared to the children of 235 normal parents. Significantly more children of disturbed parents were functionally impaired and had higher scores in the parent and youth Child Behavior Checklist total behavior scores as compared to children of normal parents. These associations were maintained even after accounting for an adverse family environment, suggesting a strong relationship between parental and childhood psychopathology as well as a mediating influence of environmental adversity.

Adaptation, Psychological↗
PubMed1990

Effect of lung T lymphocytes on fibroblasts in idiopathic pulmonary fibrosis and extrinsic allergic alveolitis.

Increased fibroblast replication and interstitial collagen accumulation occur commonly in the interstitial lung disease that progress to fibrosis. The processes controlling lung fibrogenesis are not completely understood, however. This study was designed to analyse the influence of T lymphocytes from lung tissue obtained at open lung biopsy from four patients with idiopathic pulmonary fibrosis and four patients with extrinsic allergic alveolitis on fibroblast proliferation and collagen synthesis in vitro. Lung T cell supernatants from patients with both diseases induced a moderate but significant inhibition of human lung fibroblast cell line growth. In contrast, there was a clear difference in the effect of T cells from the two groups of patients in relation to collagen production. Lung T lymphocytes from all four patients with idiopathic pulmonary fibrosis produced a substantial increase in collagen synthesis (from 371% to 514% of control values), whereas T cells from three of the four patients with extrinsic allergic alveolitis induced a significant decrease in collagen production (to 35%, 36%, and 43% of control values); in the fourth case there was an increase in collagen synthesis but this was lower than that seen with T cells from any of the patients with idiopathic pulmonary fibrosis. Peripheral T cells from six patients and control subjects caused a small increase in fibroblast proliferation and no change in collagen synthesis. The findings suggest that at least two types of interaction occur between lung T cells and fibroblasts in these disorders. A variable degree of inhibition of cell proliferation is observed in response to lung T cell supernatants from patients with both idiopathic pulmonary fibrosis and extrinsic allergic alveolitis; a substantial increase in collagen synthesis is triggered by lymphokines from patients with idiopathic pulmonary fibrosis.

Adult↗
PubMed1989

Reduction of cyclopropene by NifV- and wild-type nitrogenases from Klebsiella pneumoniae.

The nitrogenase from wild-type Klebsiella pneumoniae reduces cyclopropene to cyclopropane and propene in the ratio 1:2 at pH 7.5. We show in this paper that the nitrogenase from a nifV mutant of K. pneumoniae also reduces cyclopropene to cyclopropane and propene, but the ratio of products is now 1:1.4. However, both nitrogenases exhibit the same Km for cyclopropene (2.1 x 10(4) +/- 0.2 x 10(4) Pa), considerably more than the Km for the analogous reaction with Azotobacter vinelandii nitrogenase under the same conditions (5.1 x 10(3) Pa). Analysis of the data shows that the different product ratio arises from the slower production of propene compared with cyclopropane by the mutant nitrogenase. During turnover, both nitrogenases use a large proportion of the electron flux for H2 production. CO inhibits the reduction of cyclopropene by both K. pneumoniae proteins, but the mutant nitrogenase exhibits 50% inhibition at approx. 10 Pa, whereas the corresponding value for the wild-type nitrogenase is approx. 110 Pa. However, H2 evolution by the mutant enzyme is much less affected than is cyclopropene reduction. CO inhibition of cyclopropene reduction by the nitrogenases coincides with a relative increase in H2 evolution, so that in the wild-type (but not the mutant) the electron flux is approximately maintained. The cyclopropane/propene production ratios are little affected by the presence of CO within the pressure ranges studied at least up to 50% inhibition.

Binding Sites↗
PubMed1989

Glucose turnover rate and peripheral insulin sensitivity in alcoholic patients without liver damage.

Glucose intolerance is frequently found in alcoholic patients and an impaired insulin response has been documented in them. To look for alternative mechanisms that could explain this intolerance, a glucose turnover using tritiated glucose and an euglycemic glucose clamp were performed to measure the glucose production rate and peripheral insulin sensitivity, respectively. Two groups of recently abstinent chronic male alcoholic patients without evidence of liver damage were studied. The glucose turnover technique showed a higher basal glucose production rate in alcoholics, compared with normal volunteers (2.83 +/- 0.29 vs. 1.84 +/- 0.22 mg/kg/min); an intravenous ethanol load significantly increased this rate. The euglycemic glucose clamp did not show peripheral insulin resistance in alcoholics, compared with controls.

Adult↗
PubMed1988

Constitutive production of platelet-derived growth factor-like proteins by human prostate carcinoma cell lines.

Prostate carcinoma cell lines DU-145 and PC-3 express both platelet derived growth factor (PDGF)-1 and PDGF-2/sis genes. Concomitantly, these cells synthesize and secrete PDGF-like proteins, as judged by indirect immunofluorescence and by direct immunoprecipitation with specific PDGF antiserum. Conditioned media derived from DU-145 and PC-3 cells stimulated the incorporation of [3H]thymidine by 3T3 cells and competed with 125I-labeled PDGF for its binding to cell surface receptors of 3T3 cells. The biological activity was stable to heating at 100 degrees C for 10 min, sensitive to reducing agents, and neutralized by the IgG fraction of PDGF antiserum, properties similar to those of authentic PDGF. Both DU-145 and PC-3 cell lines appear to lack receptors for PDGF as indicated by their inability to mitogenically respond to PDGF and receptor binding of 125I-labeled PDGF. Production of PDGF-like proteins by human prostate carcinoma cells may play an important role in a paracrine mode in the organization of the extracellular matrix of the malignant tissue.

Carcinoma↗
PubMed1988

A rapid, sensitive high-performance liquid chromatography analysis of ammonia and methylamine for nitrogenase assays.

A dansyl chloride precolumn derivatization method has been developed for high-performance liquid chromatography analysis of NH3 and/or CH3NH2 produced by nitrogenase-catalyzed reduction of substrates such as N2 (NH3) or diazirine (NH3, CH3NH2). The dansyl chloride reagent can be used immediately after preparation and is stable at 4 degrees C for 1 month. The derivatization products from NH3 and CH3NH2 are prepared by direct treatment of the assay mixture (30 min of incubation) and are then stable in air and ambient light at room temperature for at least 1 day. They are separated isocratically within several minutes on a mu Bondapak C-18 reversed-phase column (Altex) at 2000-2500 psi using an eluent of 7:7:3 H2O:methanol:acetonitrile and are detected fluorometrically (368 nm excitation; 500 nm emission). The NH3 sensitivity is limited by the background NH3 in the reagents and under practical conditions is ca. 0.02 nmol (20-microliters injection volume). Methylamine sensitivity is an order of magnitude greater. The detector response for either product is linear to at least 2.4 nmol. The method is compared to alternative analytical procedures with respect to sensitivity, convenience, and absence of interferences.

Ammonia↗
PubMed1988

Fanconi's anemia lymphocytes: effect of caffeine, adenosine and niacinamide during G2 prophase.

In this investigation peripheral blood lymphocytes from 3 Fanconi's anemia (FA) patients, 2 FA heterozygotes and 4 normal subjects were treated with caffeine and/or adenosine, and/or niacinamide during G2 prophase. Caffeine dramatically increased breakage levels in homozygote and heterozygote cells. Niacinamide and adenosine decreased the amount of chromosomal aberrations detected in FA homozygote and heterozygote lymphocytes treated and untreated with caffeine during G2 prophase. Caffeine sensitivity of heterozygote lymphocytes is proposed as a new clinical test to explore heterozygosis in individuals of FA families.

Adenosine↗
PubMed1988

Cats see subjective contours.

Behavioural techniques were used to determine whether cats are able to see subjective contours. Through several stages of testing with increasingly complex displays, cats continued to respond to a figure defined by subjective contours. This result provides the first direct evidence that a nonhuman perceives subjective contours.

Animals↗
PubMed1988

[Psychiatric diagnostic classification in transcultural epidemiologic studies].

The utility of transcultural psychiatric epidemiology research is discussed as well as the methodological difficulties inherent in this type of investigation. The comparison across different cultures of the prevalence and incidence of mental illness in population studies can be used to obtain a better understanding of the risk and etiological factors involved in the development of specific psychiatric disorders. Nevertheless, most population studies have been carried out in developing countries mostly due to the complexity and high cost of these studies. As a consequence, a gap in psychiatric knowledge is created between the developed and developing countries resulting in the false notion that many of the psychiatric disorders observed in developed countries are universal to all human beings. The cross-cultural validity of certain psychiatric disorders based on the American Psychiatric Nosology (DSM III) are discussed. The article discusses the methodological difficulties which arise from the need of maintaining methods and criteria uniform in cross-cultural studies in order to allow comparisons, as well as the need of incorporating into the methodology the cultural differences existent in the manifestation or definition of the specific psychiatric disorders studied. Various possible methodologies are discussed which address this dilemma, such as the combination of empirical and ethnographic approaches and the cross-cultural comparison of empirically defined syndromes.

Anthropology, Cultural↗
PubMed1987

The Spanish Diagnostic Interview Schedule. Reliability and concordance with clinical diagnoses in Puerto Rico.

A Spanish translation of the Diagnostic Interview Schedule (DIS) was assessed using samples of Puerto Rican patients and community subjects from the San Juan area. Concordance between DIS results from psychiatrists' interviews and from laypersons' interviews was similar to results with the DIS in mainland samples. Comparisons of laypersons' DIS results with psychiatrists' clinical diagnoses yielded generally poorer agreement. Levels of agreement improved when diagnoses were clustered into higher-rank categories. These results raise cultural issues related to the use of the DIS in Puerto Rico.

Adolescent↗
PubMed1987

The prevalence of specific psychiatric disorders in Puerto Rico.

An epidemiologic survey of the lifetime and six-month prevalence rates of several psychiatric disorders was conducted in Puerto Rico. This study, carried out in 1984, applied selected schedules of a Spanish translation of the Diagnostic Interview Schedule to a stratified, island-wide probability sample of the population. With few exceptions, prevalence rates in this study were similar to those obtained in the US communities studied in the Epidemiologic Catchment Area program. The demographic correlates of the disorders are reviewed, and differences between the results of this study and those of previous studies suggesting a higher rate of mental disorder among Puerto Rican populations are discussed.

Adolescent↗