PubMed Health⌕ Search

Biomedical subjects

J A Da Silva

Publications and source records attributed to J A Da Silva.

At least 19 recordsLinked to original sources
PubMed1992

The role of pregnancy in the course and aetiology of rheumatoid arthritis.

The aetiology of rheumatoid arthritis (RA) is unknown, although being female is generally recognized as the most important independent risk factor, the disease being 2 to 3 times more frequent in females than in males. The dramatic effect of pregnancy in rheumatoid arthritis has been documented for over 50 years. This review examines the evidence and possible mechanisms by which pregnancy modifies the disease process and may alter predisposition to the development of RA in later life.

Arthritis, Rheumatoid↗
PubMed1992

Visual space perception and visually directed action.

The results of two types of experiments are reported. In 1 type, Ss matched depth intervals on the ground plane that appeared equal to frontal intervals at the same distance. The depth intervals had to be made considerably larger than the frontal intervals to appear equal in length, with this physical inequality of equal-appearing intervals increasing with egocentric distance of the intervals (4 m-12 m). In the other type of experiment, Ss viewed targets lying on the ground plane and then, with eyes closed, attempted either to walk directly to their locations or to point continuously toward them while walking along paths that passed off to the side. Performance was quite accurate in both motoric tasks, indicating that the distortion in the mapping from physical to visual space evident in the visual matching task does not manifest itself in the visually open-loop motoric tasks.

Adult↗
PubMed1992

[Spinal cord neuroschistosomiasis: clinical and laboratory evaluation of 5 cases].

Schistosomiasis mansoni is an endemic disease in Brazil. Cases of nervous system schistosomiasis have been referred in our medical literature for the past forty years. In this report five cases of schistosomiasis of the spinal cord are studied. A review of the literature has been made and some clinical, laboratory and therapeutical aspects are discussed.

Adolescent↗
PubMed1992

The effects of gender and sex hormones on outcome in rheumatoid arthritis.

Disease patterns in RA vary between the sexes; the condition is more commonly seen in women, who exhibit a more aggressive disease and a poorer long-term outcome. Men, however, are more likely than women to die from extra-articular complications of rheumatoid disease. This chapter discusses the outcome and mortality studies that substantiate these conclusions and then examines the possible mechanisms that may account for them, including the HLA system, seropositivity, compliance, response to therapy and pain threshold. In particular, sex and sex hormones emerge as independent risk factors in rheumatoid disease. The epidemiological evidence points towards a peak age of onset of RA at the time of the menopause in women and towards later in life in men. Premenopausal women may fare better than postmenopausal women with RA. The possible protective effects of the oral contraceptive pill and the dramatic amelioration with pregnancy are well documented. In vivo and in vitro studies have demonstrated that sex hormones interfere with a number of the putative processes involved in the pathogenesis of RA, including immunoregulation, interaction with inflammatory mediators and the cytokine system, and direct effects on cartilage itself. All these observations point towards the importance of gonadal hormones. However, trials on the potential therapeutic use of sex hormones in RA are limited and, as yet, disappointing. Further work is necessary to determine whether the roles of sex hormones are as central protagonists or just supporting cast in the complex arena of rheumatoid disease.

Age Factors↗
PubMed1991

Joint space in radiologically normal knees.

Joint space loss is a characteristic feature of rheumatoid arthritis and osteoarthritis. It cannot be fully evaluated, however, without knowledge of the normal variability of joint space size. We have measured joint space size using digital image analysis in a population of radiologically normal individuals. Anteroposterior films of the knee were studied from 685 consecutive patients attending Casualty with unexplained knee pain or following trauma, but with no clinical or radiological evidence of arthritis. Results show that in a radiologically normal population, men have larger joint spaces than women and there is a steady decline in joint space size with age. We found no significant difference in joint space size between weight bearing and non-weight bearing women. There was also no difference in patients presenting with pain and those presenting following an injury. Normal joint space size was not related to height, weight or body mass index in a subgroup of 213 patients. We suggest that patients lose joint space with increasing age and eventually reach a 'pain threshold' at which symptoms of osteoarthritis occur. This explains the increase in joint symptoms in those who begin with smaller joint spaces; that is in women and in the elderly.

Adolescent↗
PubMed1991

[Coronary risk factors in high-rank athletes].

PURPOSE: To report the prevalence of coronary risk factors in elite athletes. METHODS: The prevalence of coronary risk factors was determined in 88 athletes (62 men and 26 women) who participate representing Brazil, in the Olympic Games at Seul in 1988, in the Project SEUL/COB/AMIL. The risk factors analyzed were: family history of coronary heart disease, hypercholesterolemia (total-cholesterol and subfractions), hypertension, glucose intolerance, smoking and left ventricle hypertrophy (LVH). We compared the mean values of total-cholesterol/HDL-cholesterol between men and women with unpaired Student's t Test. The distribution of risk factors prevalence by sex was analysed with the chi-square test. RESULTS: Family history of coronary heart disease was detected in 11 (12.5%) athletes. Smoking was found in 12 (13.6%) athletes. There was no one with hypertension or glucose intolerance. LVH was diagnosed with the echocardiogram, in 36 athletes (40.9%). Total-cholesterol mean was 172 +/- 36 mg/dl in men and 187 +/- 34 mg/dl in women. HDL-cholesterol mean was 46 +/- 10 mg/dl in men and 60 +/- 13 mg/dl in women. Total-cholesterol/HDL-cholesterol mean was 4.02 +/- 1.39 mg/dl in men and 3.21 +/- 0.74 mg/dl in women. The difference between total-cholesterol in mean and women was not statistically significant (p less than 0.05). HDL-cholesterol and total-cholesterol/HDL-cholesterol means were statistically different (p less than 0.05). Prevalence distribution of the number of risk factors by sex were not statistically different (p less than 0.05). CONCLUSION: The results shows how important is to look for coronary risk factors in elite athletes.

Adolescent↗
PubMed1989

Constancy of individual exponents for inspired lung volume: a comment on Harver (1987).

In this paper we made two brief commentaries on Harver's (1987) experiment. The first comment is an observation on the growing area of respiratory psychophysics for which we prefer the name Behavioral Physiology. In the second comment it is suggested that the stable individual differences in the exponent of the psychophysical power law reported by Harver may be an artifact of the psychophysical method employed: category production.

Arousal↗
PubMed1986

Stability of individual psychophysical functions for perceived distance in natural indoor and outdoor settings.

Exp. 1 examined correlations of the power functions exponents for individual observers, for apparent distance in a natural indoor setting, obtained for a group of 9 observers over 5 experimental sessions separated by intersession intervals that varied from 1 day to 9 mo. Stable individual differences in the exponent of the psychophysical power law were shown. Intercorrelations of subjects' exponents were positive and reliable with 1 day between sessions and 9 mo. In Exp. 2 the estimates of apparent distance were made by 5 independent groups of 10 observers each, tested and retested at different intersession intervals. There were 5 intervals of 1 day to 9 mo. Fair temporal stability of psychophysical power function exponents was observed in most groups. In Exp. 3 psychophysical power functions were obtained from magnitude estimates of apparent distance in a natural outdoor setting. The same 10 observers were tested and then retested after 1 day and again after 1 yr. Significant correlations for both intersessions intervals indicated consistent and persisting individual differences. Taken together Exps. 1, 2, and 3, regardless of the environment in which distance estimates were performed, clearly demonstrate that power functions are repeatable, enduring, and characteristic of individuals. In addition, the mean exponents were in reasonable agreement with other reported apparent distance exponents obtained in both settings.

Adult↗
PubMed1985

Scales for perceived egocentric distance in a large open field: comparison of three psychophysical methods.

Scales for perceived egocentric distance produced by three psychophysical methods in four ranges of distances were compared. It was found that (a) the exponents produced by ratio and fractionation methods are in good agreement; (b) the exponents of both these methods were larger than those produced by magnitude estimation; (c) an increase in range of distance was associated with a decrease in exponent, but this diminution seems to interact with the method used; (d) for all the psychophysical methods used, there was large variability in the individual exponent; (e) the exponent was smaller than 1.0 for approximately 78% of the pooled sample, with all adult observers (N = 612) considered; and (f) an arithmetic mean exponent equal to 0.90 represents fairly all the results obtained.

Adult↗
PubMed1984

The protective effect of carnitine in human diphtheric myocarditis.

Carnitine, an important cofactor in the transport of fatty acids to the interior of cell mitochondria, is depleted in myocardial tissue of guinea pigs submitted to diphtheric toxin administration. Mortality rates were reduced in these animals by supplying exogenous amounts of carnitine. The accumulation of fatty acids in the cytoplasm of human heart cells reported in cases of diphtheria suggests that carnitine might possibly be depleted in human myocardium as well. For the purpose of studying the effect of carnitine administration, 132 diphtheric patients were randomly divided into two groups, one of them (carnitine-treated group, n = 73) receiving DL-carnitine, 100 mg/kg/day during 4 days after admission, in addition to routine treatment, which was prescribed for this and the control group (n = 59). The presence of myocardial damage was evaluated by clinical, electrocardiographic, radiological, and enzymatic criteria. Carnitine administration resulted in decreased incidence of heart failure (P = 0.0475), of pacemaker implants (P = 0.0256), and of lethality indexes due to myocarditis (P = 0.013). We suggest that carnitine can play an important role in the treatment of diphtheric patients.

Adolescent↗
PubMed1983

Scales for measuring subjective distance in children and adults in a large open field.

Five age levels (6, 8, 10, 12 years, and adults, N = 127) estimated distance in a large open field by the fractionation method. Scales for subjective distance were derived for each group. It was found that (a) the adults differed from all the other groups, (b) the 12-year-olds differed from the six-year-olds, (c) all the exponents were smaller than 1, (d) perceived distance in a large open field was characterized by underconstancy, and (e) underconstancy was greater for the younger subjects.

Adult↗
PubMed1983

Scaling apparent distance in a large open field: some new data.

Judged distance in a large open field, scaled by the method of magnitude estimation, is related to physical distance by a power function with an exponent smaller than unity. The exponents obtained with two ranges of distance were not affected by the availability of a standard. The mean exponent for all 80 individual power functions was 0.86, with a standard deviation of 0.11.

Adolescent↗
PubMed1978

[Familial occurrence of basilar impression].

The authors studied nine members of the same family; two among them received surgical treatment for basilar impression and Arnold-Chiari malformation. In the other members of the family, several signs and symptoms of central nervous disease were observed. All patients had the apex of the odontoid apophysis above McGregor's line, 4 mm in the case 9, and 10 mm or more in the others.

Adult↗
PubMed1975

Turner-mongolism polysyndrome. Review of the first eight known cases.

To date, a total of eight cases of the Turner-mongolism polysyndrome have been recognized. The clinical manifestations included retarded growth (resulting in a small and infantile appearance), with shield-like chest, poorly developed breasts, absent body hair, brachycephaly, short neck with foldings and low hairline, oblique eyes with epicanthal folds, squat nose, scrotal or normal tongue, abnormal hard palate (high or cleft), short hands and feet, frequent cubitis valgus, normal clitoris (may be either hypoplastic or peniform), mental retardation, and the XO/G+ karyotype, mosaic for XO in most instances. At this time, a single cause for all cases of the double aneuploidy is not known.

Abnormalities, Multiple↗