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Biomedical subjects

R A Pereira

Publications and source records attributed to R A Pereira.

At least 19 recordsLinked to original sources
PubMed2004

The relationship between parental nutritional status and overweight children/adolescents in Rio de Janeiro, Brazil.

BACKGROUND: The association between overweight parents and overweight children/adolescents was investigated in Rio de Janeiro, Brazil between 1995 and 1996, controlling for the influence of socio-economic and demographic factors. METHODS: Data were obtained from a two-stage, residence-based, random sample survey of children and adolescents aged 6-19 years and their parents. Body mass index (BMI) was used to classify nutritional status. Initially, a logistic regression model was built, using an indicator of parental weight (maternal BMI) as one of the independent variables and the child/adolescent's BMI as the dependent variable. Following that, the association between socio-economic and demographic variables and overweight children/adolescents was analysed in a univariate analysis. These variables were pre-selected for inclusion in the logistic model, provided that their levels of statistical significance were below P=0.25, and were added to the model individually according to the order of association strength in the univariate analysis. Finally, variables were retained in this model at a significance level of P=0.05. RESULTS: This study found that 20.7% of girls and 26.9% of boys were overweight, with a larger prevalence among children aged less than 9 years. In addition to maternal BMI, the predictors of overweight children and adolescents were age, gender and the number of people in a house. CONCLUSIONS: These results demonstrate the relationship between maternal nutritional status and overweight children and adolescents, suggesting that obesity-prevention programmes should be focused on the family.

Adolescent↗
PubMed2002

Heavy metals in soft tissues of Tursiops truncatus and Delphinus delphis from west Atlantic Ocean by X-ray spectrometry.

In this work, the concentration of heavy metals in muscle, liver, fat tissue and skin is studied in 15 Delphinus delphis and two Tursiops truncatus dolphins, stranded along the Portuguese coast of the Atlantic Ocean. Sample collection was performed post-mortem and the tissues were kept frozen until analysed. Sample preparation included lyophilising and grounding in a Teflon mill to avoid contamination by metals. The obtained powder was prepared as pellets for each sample and analysed directly by X-ray fluorescence spectrometry. The concentrations of K, Ca, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Br, Rb, Sr, Hg and Pb were obtained. Significant differences between the muscle, the skin and the fat tissues were detected. Cobalt concentrations were similar in liver, skin and muscle. The levels of Ni, Rb and Sr are at the level of the detection limit and whenever measurable are rather constant in all the analysed tissues. The results show that the highest concentrations of Mn, Cu and Hg are always in liver tissues. Zinc and Se concentrations are higher in skin and Pb is present in very low concentrations in all the analysed tissues except in skin; Fe and As are enhanced in muscle and liver. In general, the two studied species did not seem to differ significantly in their heavy metals concentration in a given tissue.

Adipose Tissue↗
PubMed2001

Cutting edge: a NK complex-linked locus governs acute versus latent herpes simplex virus infection of neurons.

Herpes simplex causes latent infections that periodically reactivate. Specific immunization attempts are failing to control herpes, prompting a fresh look at which host responses predominate. We report a NK complex-linked genetic locus, Rhs1, whose alleles influence the magnitude of experimental herpes simplex. Rhs1 provided rapid control of primary infection but caused a reciprocal increase in the number of latently infected neurons. Thus, in principle, establishment of latency is a consequence of efficient front line defense against herpesvirus infection. Based on conservation between human and mouse NK complexes, the data predict the presence of a human Rhs1 orthologue on chromosome 12p12-13.

Acute Disease↗
PubMed2001

Factors associated with overweight and central body fat in the city of Rio de Janeiro: results of a two-stage random sampling survey.

The purpose of the survey was to investigate the association of overweight (body mass index, BMI) and central body fat distribution (waist/hip girth ratio WHR) with socio-economic, demographic, lifestyle and dietary variables in the adult population of Rio de Janeiro City, Brazil, 1995-1996. A two-stage random sample population-based survey was performed, with 1455 males and 1906 females above 20 y old resident in Rio de Janeiro City, Brazil. Data were obtained by direct interview and physical examination of the subjects. The intake of selected nutrients (fat, saturated fat, cholesterol) and energy was obtained from a semi-quantitative food frequency questionnaire (FFQ). Variables with at least a marginal univariate association with the dependent variables (BMI and WHR) were selected as predictors in two logistic regression models, and variables statistically significant (P<0.05) were retained in them. Overweight prevalence was 44.9%, and 39.2% of the subjects had excessive central body fat distribution (elevated WHR). The proportions of subjects with an excessive intake of fat, saturated fat and cholesterol were respectively 31%, 42% and 47%. For the BMI model, the variables retained were age (OR=1.5, 95% CI=1.3-1.7), schooling (OR=1.7, 1.4-1.9) and smoking (OR=0.8; 0.7-0.9); and for WHR, age (OR=1.8, 1.5-2.1), schooling (OR=2.2, 1.9-2.6), occupation (OR=1.8, 1.1-2.0) and gender (OR=3.9, 3.2-4.7). Obesity and excessive central body fat are highly prevalent health problems in the studied population. As suggested by the identified risk factors, they should be urgently addressed through health nutrition education and physical activity programs; particularly those directed to the middle aged and female groups.

Adult↗
PubMed2001

High prevalence of hypertension among Black and Mulatto women in a Brazilian survey.

STUDY OBJECTIVES: Brazil has a high admixture of Blacks and Whites, making it possible to compare the prevalence of hypertension among Blacks, Whites, and Mulattos. DESIGN: A population-based health and nutrition survey was carried out in 1996 in the city of Rio de Janeiro, Brazil. Blood pressure, weight, height, food frequency information, and skin color were obtained from a sample of 2,802 private household residents aged 20 years or older. MAIN OUTCOME MEASURE: Hypertension was defined as systolic blood pressure >140 mm Hg and/or diastolic pressure >90 mm Hg or the use of antihypertensive medication. RESULTS: The prevalence of hypertension among men was 12.0% among Whites, 13.8% among Mulattos, and 14.4% for Blacks. For women, these prevalences were 12.0%, 16.4%, and 20.2%, respectively. After adjustment for age, calcium and salt intake, physical activity level, body mass index, and waist-hip ratio, we observed (among women only) a trend toward increasing prevalence of hypertension with increasing skin darkness. The adjusted odds ratio of hypertension was 1.52 for Mulatto women compared to Whites and 2.27 for Blacks compared to Whites (P<.05). With further adjustment for income, the odds ratios were reduced to 1.30 (95% CI 0.86-1.95) and 1.75 (95% CI 1.04-2.94). CONCLUSIONS: Black women showed increased risk of hypertension independent of socioeconomic factors or overweight status.

Adult↗
PubMed2000

Short stature and hypertension in the city of Rio de Janeiro, Brazil.

OBJECTIVE: Stature is a powerful indicator of poor nutrition early in life in nations where undernutrition is a public health problem. Hypertension in adults has been associated with factors present early in life such as low birth weight. We tested the hypothesis that short stature is associated with hypertension among adults. DESIGN AND SETTING: A household survey of representative adults in Rio de Janeiro city, Brazil was carried out in 1996. SUBJECTS: Blood pressure and anthropometric measures were collected from 2802 adults in their own households. Prevalence estimates and modelling incorporated the sample design and weights. RESULTS: Age-adjusted prevalence of hypertension for both sexes was lower in the third quartile of stature distribution. In women, but not in men, the odds ratio comparing the first quartile of stature with the fourth quartile was statistically significant with an odds ratio of 1.68 (95%CI 1.02-2.76). Adjusting for known risk factors for hypertension such as age, income, smoking, sodium and alcohol intake and race, the association among women, comparing the first with the fourth quartile for stature, was 1.84 (95%CI 1.03-3.30). With further adjustment for residual of weight on height the ratio reduced to 1.76 (95% CI 0.97-3.19, P value of trend = 0.03). Systolic blood pressure showed a U-shaped association with quartiles of stature, mainly among women, with a beta-coefficient significantly lower at the third quartile. CONCLUSIONS: This association of stature with hypertension supports the theory of an important ontogenetic dependence of adult blood pressure, at least among women.

Adult↗
PubMed2000

Upregulation of neuronal amyloid precursor protein (APP) and APP mRNA following magnesium sulphate (MgSO4) therapy in traumatic brain injury.

The aim of this study was to assess and quantitate topographically the effects of posttraumatic intravenous magnesium sulphate (MgSO4) on neuronal perikaryal APP antigen and messenger RNA (mRNA) expression in sheep brains 2 h after a controlled focal head impact. The percentage brain area with APP immunoreactive neuronal perikarya was 71, 56, 27.5 and 5.5%, respectively, in MgSO4-treated head-injured animals, head-injured animals without any treatment, MgSO4 treated nonimpacted animals, and nontreated nonimpacted control sheep. Although there was no statistically significant difference in APP immunoreactive neuronal perikarya in the MgSO4-treated HI group (mean 71%) compared to the HI group without any treatment (mean 56%), northern analysis showed that there was a 2.3-+/-0.2-fold increase in APP mRNA in the thalamus of treated impacted animals compared to untreated impacted animals (p < 0.005). However, MgSO4 treated nonimpacted control animals also showed a 1.6-+/-0.1-fold increase in APP mRNA compared to untreated nonimpacted controls (p < 0.005). MgSO4 therapy results in upregulation of neuronal APP mRNA and APP expression that is quantitatively greater following a focal head impact.

Amyloid beta-Protein Precursor↗
PubMed2000

Granzyme A, a noncytolytic component of CD8(+) cell granules, restricts the spread of herpes simplex virus in the peripheral nervous systems of experimentally infected mice.

Control of ganglionic herpes simplex virus (HSV) infection depends on CD8(+) cells but not on the death of infected neurons. Primarily, perforin and granzyme B mediate CD8(+) cell cytotoxicity, whereas the in vivo functions of granzyme A, a third granule protein, are unknown. Here, it is shown that granzyme A restricts the interneuronal spread of HSV and significantly influences ganglionic virus load.

Animals↗
PubMed1999

Upregulation of amyloid precursor protein messenger RNA in response to traumatic brain injury: an ovine head impact model.

There is evidence that the amyloid precursor protein (APP) plays an important role in neuronal growth and synaptic plasticity and that its increased expression following traumatic brain injury represents an acute phase response to trauma. We hypothesized that the previously described increased APP expression in response to injury (Van den Heuvel et al., Acta Neurochir. Suppl. 71, 209-211) is due to increased mRNA expression and addressed this by examining the expression of APP mRNA and APP within neuronal cell bodies over time in an ovine head impact model. Twenty-five anesthetized and ventilated 2-year-old Merino ewes sustained a left temporal head impact using a humane stunner and 9 normal sheep were used as nonimpact controls. Following postimpact survival periods of 15, 30, 45, 60, and 120 min, brains were perfusion fixed in 4% paraformaldehyde and examined according to standard neuropathological protocol. APP mRNA and antigen expression were examined in 5-microm sections by nonisotopic in situ hybridization and APP immunocytochemistry. The percentage of brain area with APP immunoreactivity within neuronal cell bodies in the impacted animals increased with time from a mean of 7.5% at 15 min to 54.5% at 2 h. Control brains showed only very small numbers of weakly APP-positive neuronal cell bodies ranging from 2 to 14% (mean 7%). Increased expression of APP mRNA was first evident in impacted hemispheres at 30 min after impact and progressively increased over time to involve neurons in all sampled regions of the brain, suggesting increased transcription of APP. In contrast, APP mRNA was undetectable in tissue from nonimpacted sheep. These data show that APP mRNA and antigen expression are sensitive early indicators of neuronal injury with widespread upregulation occurring as early as 30 min after head impact.

Amyloid beta-Protein Precursor↗
PubMed1999

Cell surface expression of H2 antigens on primary sensory neurons in response to acute but not latent herpes simplex virus infection in vivo.

CD8(+) T lymphocytes and class I major histocompatibility complex (MHC-I) molecules profoundly influence the severity of neuronal herpes simplex virus (HSV) infection in experimentally infected mice. Paradoxically, neurons are classically regarded as MHC-I deficient. However, it is shown here that H2-encoded heavy chains (alphaCs) and their associated light chain, beta2 microglobulin, are present on the surfaces of primary sensory neurons recovered from sensory ganglia within 1 to 2 weeks of HSV infection. During this time, some neurons are found to be tightly associated with T cells in vivo. Prior data showed that termination of productive HSV infection in the peripheral nervous system is not dependent on cell-mediated lysis of infected neurons. Consistent with these data, immunogold electron microscopy showed that the density of cell surface H2 on neurons is an order of magnitude lower than on satellite glia, which is predicted to favor a noncytolytic CD8 cell response.

Animals↗
PubMed1999

[Using food frequency questionnaire in past dietary intake assessment].

This paper aims to discuss which one is the best estimator of past diet: a retrospective report or a recent diet recall. The analysis included 13 articles published between 1984-1997 and selected from a MEDLINE search and from other reviews on this subject. The selection criterion was the use of a food frequency questionnaire (FFQ) in a validation study of retrospective report of dietary intake in remote past. Literature review shows that even taking into account misclassification, retrospective report of diet usually yields to a more reliable estimate of past diet pattern than current report. Past diet recall was strongly influenced by current intake and by diet patterns change. Analyzed investigations indicate that agreement between original and retrospective report was higher either for foods eaten rarely or frequently and lower for foods moderately consumed. This review allows considering the FFQ as a valuable instrument when studying the role of diet on the etiology of chronic diseases.

Diet Surveys↗
PubMed1999

Restricted replication of herpes simplex virus in satellite glial cell cultures clonally derived from adult mice.

To determine the possible influence of satellite glial cells on restricting the spread of herpes simplex virus in the peripheral nervous system, HSV replication was studied in clonally derived cultures of satellite glial cells from adult animals. Satellite cells were purified by exploiting their close anatomical association with primary sensory neurons. Dissociated neurons from dorsal root ganglia were micro-manipulated to remove all but one of the attached satellite cells and cultured in the presence of the mitogenic stimulators bovine pituitary extract and cholera toxin. Following a lag phase of 20-30 days some of the individual satellite cells began to proliferate. Initial cultures demonstrated bipolar morphology similar to cultured Schwann cells, some of which differentiated into large astrocytic whorl-like cells on subsequent passage. Immunocytochemical and molecular studies demonstrated that these cells, designated Sat.1, express glial fibrillary acidic protein, confirming their glial origin and by electron microscopy they were shown to be phagocytic. Under single step viral growth conditions Sat.1 cells were restrictive for HSV replication, producing in the order of 1000 times less infectious virus than Vero cells, a standard permissive cell line. These results suggest that satellite cells, which tightly encase sensory neurons, play a role in restricting interneural spread of HSV within the peripheral nervous system.

Animals↗
PubMed1997

[Multifactorial analysis of risk factors for low birth weight in Salvador, Bahia].

This study is a multifactorial analysis of the risk factors for low birthweight in a group of newborns in an urban area of Brazil. A total of 1023 infants born in four maternity units in Salvador, Bahia, between July 1987 and February 1988 were included in the study. The sources of information were clinical histories and interviews with the mothers in the maternity units. The analysis was by means of logistic regression. In the final model the risk factors were the following: maternal age less than 21 years or more than 35; gestational age less than 38 weeks; unfavorable outcome of an earlier pregnancy; interval of 12 months or less since prior birth; tobacco smoking; and hypertension. The population attributable risk values for the risk factors included in the final model are presented. These factors should be used to identify pregnant women at high risk of giving birth to a low-birthweight baby, in order to provide them with more prenatal care.

Brazil↗
PubMed1994

Upregulation of class I major histocompatibility complex gene expression in primary sensory neurons, satellite cells, and Schwann cells of mice in response to acute but not latent herpes simplex virus infection in vivo.

Major histocompatibility complex (MHC) deficiency is typical of almost all resident cells in normal neural tissue. However, CD8+ T cells, which recognize antigenic peptides in the context of class I MHC molecules, are known to mediate clearance of herpes simplex virus (HSV) from spinal ganglia of experimentally infected mice, leading to the hypothesis that class I expression in the peripheral nervous system must be upregulated in response to HSV infection. In addressing this hypothesis it is shown, in BALB/c (H-2d) mice, that normally deficient class I transcripts transiently accumulate in peripheral nerve Schwann cells, ganglionic satellite cells, and primary sensory neurons, indicating that in each of these cell types class I expression is regulated at the transcriptional level in vivo. Furthermore, for 3-4 wk after infection, H-2Kd/Dd antigens are expressed by satellite and Schwann cells but not neurons, suggesting additional posttranscriptional regulation of class I synthesis in neurons. Alternatively, the class I RNAs induced in neurons may not be derived from classical class I genes. Factors regulating H-2 class I expression emanate from within infected ganglia, probably from infected neurons themselves. However, induction of class I molecules was not maintained during latency, when viral gene expression in neurons is restricted to a single region within the virus repeats. These data have implications for the long-term survival of cells in HSV-infected neural tissue.

Acute Disease↗
PubMed1994

Two subpopulations of human triple-negative thymic cells are susceptible to infection by human immunodeficiency virus type 1 in vitro.

Some infants infected with human immunodeficiency virus type 1 (HIV-1) rapidly develop a fatal disease characterized by a severe lymphopenia. To explain the immune dysfunction, we proposed a mechanism by which a nongeneration of CD4+ T cells is caused by HIV-1 infection of thymic cells. To examine this hypothesis, we infected primary triple-negative (TN; phenotypically CD3- CD4- CD8-), CD1a- TN, or CD1a+ TN thymic cell subsets. Our data indicate that by flow cytometry, TN, CD1a- TN, and CD1a+ TN cells remain CD4 negative throughout the culture period. We demonstrated that TN and CD1a+ TN thymic cell subsets are susceptible to HIV-1 as is the entire thymic cell population, whereas CD1a- TN cells are not. A limited number of infected TN cells are expressing HIV-1 but the level of transcription is very high in permissive cells, as detected by in situ hybridization. We then performed blocking experiments on TN cells to examine the mechanism of HIV-1 entry into these cells. CD4 (OKT4a) monoclonal antibody blocks their infection. Finally, infection experiments on two subpopulations of TN cells (CD2+ CD7+ and CD2- CD7-) indicate that infected TN cells may correspond to both immature thymocytes and thymic dendritic cells. These data are of particular interest since infection of thymic stromal cells might result in an impairment of T-cell differentiation, which may explain a nongeneration of functional CD4+ T-cell population in the thymus. This phenomenon may play a role in AIDS pathogenesis, in particular in infants born from seropositive mothers.

Antibodies, Monoclonal↗
PubMed1986

Comparison of functional properties of thymic and splenic dendritic cells.

Murine dendritic cells (DC) which are negative for surface immunoglobulin (sIg), Fc receptor (FcR), Thy-1 antigen, and the mononuclear phagocyte-specific marker F4/80, but positive for the DC-specific marker 33D1 and major histocompatibility complex (MHC) Class 1 and Class II antigens were obtained from either the spleen (SDC) or thymus (TDC) and used to stimulate alloreactive cytotoxic T lymphocyte (Tc) generation in vitro, in 5-day mixed lymphocyte reaction (MLR) to investigate some of their functional properties. SDC were potent stimulators of Tc cells in the absence of supernatant of concanavalin-A-stimulated spleen cells (CSS) and using medium containing 1% thioglycolate-stimulated mouse serum (TMS) to avoid potential artifactual helper T cell activation by fetal calf serum (FCS) antigens. TDC did not stimulate Tc cells under these conditions, but did so when mixed with small numbers of SDC, or in the presence of CSS. 33D1 and complement (C')-treated SDC and TDC populations failed to stimulate Tc cell responses in the absence of CSS. In the presence of CSS, TDC treated in a similar manner did not stimulate Tc cell activity, while 33D1 and C'-treated SDC stimulated a weak but detectable Tc cell response. These results indicate that genuine DC were the dominant cells presenting Class I MHC antigens in the TDC population and also that a minority of contaminating non-DC in the SDC population expressed sufficient MHC Class I antigens for Tc cell activation, but did not produce factor(s) required for Tc cell activation. The pretreatment of SDC and TDC with CSS before using them as stimulators did not improve their ability to stimulate Tc cell responses, indicating that the effect of CSS in improving the ability of TDC to stimulate Tc cell responses was not solely due to MHC-elevating effects of components of CSS. Lipopolysaccharide (LPS)-treated SDC synthesized abundant interleukin 1 (IL-1), but TDC synthesized low levels of IL-1. Contact for 24 hr between TDC and splenic Tc cell precursors in medium containing 1% TMS but without CSS and FCS did not tolerize the T cells.

Animals↗