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J M de Souza

Publications and source records attributed to J M de Souza.

At least 19 recordsLinked to original sources
PubMed2006

Effects of mercury intoxication on the response of horizontal cells of the retina of thraira fish (Hoplias malabaricus).

Methyl mercury (MeHg) is highly neurotoxic, affecting visual function in addition to other central nervous system functions. The effect of mercury intoxication on the amplitude of horizontal cell responses to light was studied in the retina of the fish Hoplias malabaricus. Intracellular responses were recorded from horizontal cells of fish previously intoxicated with MeHg by intraperitoneal injection (IP group) or by trophic exposure (T group). Only one retina per fish was used. The doses of MeHg chloride administered to the IP group were 0.01, 0.05, 0.1, 1.0, 2.0, and 6.0 mg/kg. The amplitudes of the horizontal cell responses were lower than control in individuals exposed to 0.01 (N = 4 retinas), 0.05 (N = 2 retinas) and 0.1 mg/kg (N = 1 retina), whereas no responses were recorded in the 1.0, 2.0, and 6.0 mg/kg groups. T group individuals were fed young specimens of Astyanax sp previously injected with MeHg corresponding to 0.75 (N = 1 retina), 0.075 (N = 8 retinas) or 0.0075 (N = 4 retinas) mg/kg fish body weight. After 14 doses, one every 5 days, the amplitude of the horizontal cell response was higher than control in individuals exposed to 0.075 and 0.0075 mg/kg, and lower in individuals exposed to 0.75 mg/kg. We conclude that intoxication with MeHg affects the electrophysiological response of the horizontal cells in the retina, either reducing or increasing its amplitude compared to control, and that these effects are related to the dose and/or to the mode of administration.

Animals↗
PubMed2005

Raman spectra of deuteriated taurine single crystals.

The polarized Raman spectra of partially deuteriated taurine [(ND3+)0.65(NH3+)0.35(CH2)2SO3-] crystals from x(zz)x and x(zy)x scattering geometries of the Ag and Bg irreducible representations of the factor group C2h are reported. The temperature-dependent Raman spectra of partially deuteriated taurine do not reveal any evidence of the structural phase transition undergone by normal taurine at about 250 K, but an anomaly observed in the 180 cm-1 band at approximately 120 K implies a different dynamic for this band (which is involved in a pressure-induced phase transition) in the deuteriated crystal.

Argon↗
PubMed2004

Contrast sensitivity threshold measured by sweep-visual evoked potential in term and preterm infants at 3 and 10 months of age.

Although healthy preterm infants frequently seem to be more attentive to visual stimuli and to fix on them longer than full-term infants, no difference in visual acuity has been reported compared to term infants. We evaluated the contrast sensitivity (CS) function of term (N = 5) and healthy preterm (N = 11) infants at 3 and 10 months of life using sweep-visual evoked potentials. Two spatial frequencies were studied: low (0.2 cycles per degrees, cpd) and medium (4.0 cpd). The mean contrast sensitivity (expressed in percentage of contrast) of the preterm infants at 3 months was 55.4 for the low spatial frequency (0.2 cpd) and 43.4 for the medium spatial frequency (4.0 cpd). At 10 months the low spatial CS was 52.7 and the medium spatial CS was 9.9. The results for the term infants at 3 months were 55.1 for the low spatial frequency and 34.5 for the medium spatial frequency. At 10 months the equivalent values were 54.3 and 14.4, respectively. No difference was found using the Mann-Whitney rank sum T-test between term and preterm infants for the low frequency at 3 or 10 months or for the medium spatial frequency at 3 or 10 months. The development of CS for the medium spatial frequency was equally fast for term and preterm infants. As also observed for visual acuity, CS was equivalent among term and preterm infants, suggesting that visual experience does not modify the development of the primary visual pathway. An earlier development of synapses in higher cortical visual areas of preterm infants could explain the better use of visual information observed behaviorally in these infants.

Contrast Sensitivity↗
PubMed2001

Ultraviolet colour opponency in the turtle retina.

We have examined the functional architecture of the turtle Pseudemys scripta elegans retina with respect to colour processing, extending spectral stimulation into the ultraviolet, which has not been studied previously in the inner retina. We addressed two questions. (i) Is it possible to deduce the ultraviolet cone spectral sensitivity function through horizontal cell responses? (ii) Is there evidence for tetrachromatic neural mechanisms, i.e. UV/S response opponency? Using a constant response methodology we have isolated the ultraviolet cone input into the S/LM horizontal cell type and described it in fine detail. Monophasic (luminosity), biphasic L/M (red-green) and triphasic S/LM (yellow-blue) horizontal cells responded strongly to ultraviolet light. The blue-adapted spectral sensitivity function of a S/LM cell peaked in the ultraviolet and could be fitted to a porphyropsin cone template with a peak at 372 nm. In the inner retina eight different combinations of spectral opponency were found in the centre of the receptive field of ganglion cells. Among amacrine cells the only types found were UVSM-L+ and its reverse. One amacrine and four ganglion cells were also opponent in the receptive field surround. UV/S opponency, seen in three different types of ganglion cell, provides a neural basis for discrimination of ultraviolet colours. In conclusion, the results strongly suggest that there is an ultraviolet channel and a neural basis for tetrachromacy in the turtle retina.

Animals↗
PubMed1998

[Case-control design in cardiovascular disease epidemiology. II--Analysis of data].

The wide spread distribution of statistical software recommended for multivariate analysis as well as the ease in handling it can lead the users into adopting wrong measures if they do not pay attention to the theoretical principles behind those methods. With a view to bringing out some of these principles some steps for the data analysis of a case-control study undertaken in the city of S. Paulo-Brazil from March, 1993 to February, 1994 in order to test the association between diabetes mellitus and ischaemic heart disease after adjusting for potential confounders and/or modifiers of effect are presented. Methodologic issues are emphasized in the development of four steps: a) the data bank structure: b) the calculation of statistical power; c) the definition of variables strata and codification and d) the choice of the logistic regression method.

Case-Control Studies↗
PubMed1997

[Reproducibility of data in a study of the risk factors for insulin-dependent diabetes mellitus].

The reliability of information about mothers' and fathers' education, weight and height at birth, history of diarrhoea, duration of exclusive breast feeding and age of introduction of cows' milk products, selected from a structured questionnaire used in home interviewers was examined in a sample of 38 cases and 38 controls from a study related to the risk factors of insulin-dependent diabetes mellitus. The repetition of the questions was done by telephone. The agreement between the answers of both interviewers was verified using the kappa statistic (categorical variables) and the intra-class correlation coefficient (quantitative variables). The results enable one to conclude that the information is reproducible.

Birth Weight↗
PubMed1997

Electrophysiological measurements of spectral sensitivities: a review.

Spectral sensitivities of visual systems are specified as the reciprocals of the intensities of light (quantum fluxes) needed at each wavelength to elicit the same criterion amplitude of responses. The review primarily considers the methods that have been developed for electrophysiological determinations of criterion amplitudes of slow-wave responses from single retinal cells. Traditional flash methods can require tedious dark adaptations and may yield erroneous spectral sensitivity curves which are not seen in such modifications as ramp methods. Linear response methods involve interferometry, while constant response methods involve manual or automatic adjustments of continuous illumination to keep response amplitudes constant during spectral scans. In DC or AC computerized constant response methods, feedback to determine intensities at each wavelength is derived from the response amplitudes themselves. Although all but traditional flash methods have greater or lesser abilities to provide on-line determinations of spectral sensitivities, computerized constant response methods are the most satisfactory due to flexibility, speed and maintenance of a constant adaptation level.

Color Perception↗
PubMed1997

Dietary patterns in Japanese migrants to southeastern Brazil and their descendants.

This paper describes the dietary patterns of people of Japanese ancestry living in São Paulo, Brazil. Two cross-sectional surveys using a food frequency questionnaire (in 1989 and 1995) and self-administered three-day food record (only in 1995) were carried out in randomly chosen first-generation (Japan-born) and second-generation (Brazil-born) Japanese living in the city of São Paulo (n = 166), aged 40-69 years at the time of the first survey (1989). Daily intake of rice, bread, milk, fruits and coffee, and infrequent consumption of pork, green tea, black tea, tsukemono (pickled vegetables), seaweed and mushrooms were reported. The mean (+/- standard deviation) daily proportions of energy from fat among Japan-born participants were 27.2 +/- 6.7% for men and 26.2 +/- 6.7% for women. The respective figures for Brazil-born Japanese were 30.1 +/- 7.4% and 29.5 +/- 6.4%. These values were quite close to recent estimates for the general Brazilian population in metropolitan areas (about 30%), but seem to be higher than available data from Japan (25.3%). Dietary changes in this migrant population are discussed with focus on nutrients currently implicated in the etiology of major chronic diseases.

Aged↗
PubMed1997

IDDM and milk consumption. A case-control study in São Paulo, Brazil.

OBJECTIVE: To test the hypothesis that breast-feeding is a protective factor against IDDM and that early exposure to cow's milk is a risk factor for the disease. RESEARCH DESIGN AND METHODS: A case-control study was conducted in São Paulo, Brazil. A total of 346 diabetic children, aged < 18 years, were identified in two institutions in the city of São Paulo. Duration of exclusive breast-feeding and age of introduction to cow's milk products in infant diet were compared with 346 sex-, age-, and neighborhood-matched control children. All comparisons between diabetic and control children were done using paired tests. RESULTS: Statistically significant differences were found for the duration of exclusive breast-feeding (P = 0.007) and for the age of introduction to cow's milk products (P = 0.047). Control children had a longer time of exclusive breast-feeding and had received cow's milk later in their diet than the case children. CONCLUSIONS: The results suggest that a shorter duration of exclusive breast-feeding is a risk factor for IDDM (odds ratio [OR] 2.13; 95% CI 1.8-3.55) and that the introduction to cow's milk products before age 8 days is a risk factor for the disease.

Adolescent↗
PubMed1997

[Anemia in the first year of life and its relation to breast-feeding].

INTRODUCTION: Many studies in this field justify the hypothesis that early weaning is one of the causes of anemia in the first year of life. This study seeks to discover the prevalence of iron deficiency anemia and its relation to the duration of breast-feeding among infants aged 0-12 months. MATERIAL AND METHOD: A sample of 317 infants of four school health centers in the city of S. Paulo (Brazil) was studied. The information about diet was obtained by interviewing the mothers. The presence of anemia was verified by hemoglobin concentration, using the cianometahemoglobin method, and the criteria recommended by the World Health Organization (WHO) were utilized for the diagnosis. The duration of exclusive breast feeding was calculated by using the life table technique for censored data. RESULTS: The prevalence of anemia was found to be 14.5% for the whole population and 22.6% for infants aged more than 180 days. No association was found between anemia and time of breast-feeding; the median time were the same for both groups, anemic and non-anemic. COMMENTS: The results observed are more probably related to the demographic characteristics of the population studied and by no means lessen the importance of exclusive breast feeding in the prevention of anemia.

Anemia, Iron-Deficiency↗
PubMed1997

[Dose-response effect of risk factors for ischemic heart disease in males].

PURPOSE: Several authors have reported hypertension, smoking and hypercholesterolemia as independent risk factors for ischemic heart disease (IHD), but few of them have investigated the existence of a linear gradient related to the levels of these exposures and IHD. We evaluated the effect of different levels of these exposures and IHD after adjusting for known confounders. METHODS: The study was designed as a case-control and the period of data collection was from March/93 until February/94. The sample was composed of 547 men aged 30-69 years living in the city of São Paulo. We compared 192 cases with 355 controls (172 neighbourhood controls and 183 hospital controls). Logistic regression was the statistical method used to analyse of the data. RESULTS: The results showed a linear gradient for known duration of hypertension, known duration of hypercholesterolemia and daily number of cigarettes smoked. The variables known duration of diabetes mellitus and duration of smoking did not present such a tendency. CONCLUSION: Some methodological issues are presented to explain the absence of a linear gradient for known duration of diabetes mellitus and duration of smoking. It is concluded that the dose-response effect detected for known duration of hypertension, known duration of hypercholesteremia and daily number of cigarettes consumed were independent of the presence of major risk factors for ischemic heart disease.

Adult↗
PubMed1996

An AC constant-response method for electrophysiological measurements of spectral sensitivity functions.

A number of methods have been used in the past to measure spectral sensitivity (S(lambda)) functions of electric responses in the visual system. We present here a microcomputer based, AC, constant-response method for automatic on-line measurement of S(lambda) in cells with or without a sustained tonic response. It is based on feedback adjustment of light intensity to obtain constant peak-to-peak amplitudes of response to a flickering stimulus as the spectrum is scanned between 300 and 700 nm in 4 nm steps. It combines the advantages of: (1) on-line presentation of S(lambda) curves; (2) constant light adaptation; (3) sampling of many points; and (4) fast data collection time. The system can be applied to sensitivity or threshold (e.g., S(lambda), dark adaptation, receptive field) measurements of any electrically recorded visual response.

Animals↗
PubMed1996

[Diabetes mellitus and ischemic heart disease: case-control study].

Several works have been reported diabetes as an independent risk factor for ischaemic heart disease. The use of different methodologies have been an obstacle to a comparison of these studies. The study realized has sought to test the association between diabetes and ischaemic heart disease, after adjusting for known confounders and/or modifiers of effect. The study was designed as a case control study and the period of data collection was one year (March/93 to February/94). The cases were compared with three kinds of controls in two base-populations: primary and secondary. The sample was composed of 833 individuals of both genders of 30-69 years of age living in the city of S. Paulo, Brazil. Logistic regression was the statistical method used for the analysis of the data. The results showed that diabetes was not an independent risk factor for IHD. Hypertension, hypercholesterolemia, smoking and family antecedents of cardiovascular diseases were considered major risk factors for ischaemic heart disease. The interaction between diabetes and exposure levels of the others variables did not present statistical significance. Some methodological issues are presented to explain different magnitudes of effect according to the different kinds of controls. It is concluded that the presence of major risk factors in the models contributed to the disappearance of the association between diabetes and ischaemic heart disease.

Adult↗
PubMed1996

[Diabetes mellitus and ischemie heart disease. Comparison by gender].

PURPOSE: To test the association between diabetes mellitus and ischaemic heart disease (IHD) in males and females, after adjusting for known confounders and/or modifiers of effect. METHODS: The study was designed as a case-control and the period of data collection was one year (March/93 until February/94). The association between diabetes mellitus and IHD was evaluated in each one of two groups: one composed by men the other by women, aged 30-69 years living in the city of São Paulo. The respective samples sizes were 547 and 286. Logistic regression was the statistical method used to do the analysis of the data. RESULTS: There were similar odds ratios in both genders and diabetes was not considered an independent risk factor for IHD. In each one of the groups the variables hypertension, hypercholesterolemia, smoking and familial history were considered independent risk factors to IHD. The interaction between diabetes and exposures levels of other variables was not statistically significant. CONCLUSION: The presence of major risk factors in the models contributed to the disappearance of the association between diabetes mellitus and IHD.

Adult↗
PubMed1995

Cranio-orbital approach for the paraclinoidal and anterior communicating aneurysms.

Aneurysms arising at the proximal intracranial carotid artery (between cavernous sinus and posterior communicating artery) and at the anterior communicating complex may present with technical difficulties regarding appropriate access without excessive brain retraction. In a series of 15 patients the authors show the use of the cranio-orbital approach, formerly designed in the access of skull base tumors, for these subgroups of aneurysms. They discuss the advantages of a basal avenue in minimizing brain retraction, better anatomical orientation, obviation of tissue ressection and easier extra-dural bone removal. It was not identified any complication due to the described approach.

Adult↗
PubMed1995

[Risk factors for cancer of the esophagus: a case control study in a metropolitan area of south-eastern Brazil].

The association between esophageal cancer and smoking and drinking habits, instruction and nutritional factors was examined by means of the utilization of data of a case-control study which was undertaken in the city of S. Paulo (Brazil). Eighty five cases were compared with two hundred and ninety two hospital controls, with different diseases, including other kinds of cancer. The crude estimations of the odds ratios were calculated for all the variables. Logistic regression was used in the next steps of the analysis. The drinking habit [odds ratio = 3.68, 95% confidence interval (1.74 - 7.78)], the smoking habit [odds ratio 4.86; 95% confidence interval (1.95 - 12.13)] and the frequent eating of hot pepper [odds ratio = 2.48; 95% confidence interval (1.46 - 4.23)] are important risk factors for the disease. The estimate of odds ratio for smoking ordinary cigarette was 3.43 (1.31-8.97) and for smoking of corn straw hand-rolled cigarrette was of 4.18 (1.38-12.66).

Adult↗
PubMed1994

[Cleft lip and palate: case-control study].

This study relates to a case-control analysis for the purpose of verifying the association between oral clefts and possible risk factors. The analysed variables were: place of mother's residence (urban/rural), pollution, parental diseases, mother's diseases during the first four months of pregnancy, intake of drugs related to this period, heredity, smoking habits, alcohol consumption and X-ray examinations during pregnancy or X-ray examinations prior to pregnancy. There were 450 cases of clefts of whom 354 had a cleft lip with or without cleft palate and 96 had a cleft palate. The relative risk (RR) for each variable by was estimated points and at a 95% of confidence interval and multivariate analysis was applied. As regards cleft lip with or without cleft palate, the risk factors are heredity (RR = 4.96), epilepsy in the mother (RR = 2.39) and the intake of drugs such as anti-inflammatory substance in the first four months of pregnancy (RR = 2.59). Related to cleft palate, the risk factors are heredity (RR = 2.82) and pollution (RR = 2.58).

Brazil↗