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Biomedical subjects

A P da Silva

Publications and source records attributed to A P da Silva.

13 recordsLinked to original sources
PubMed2001

The influence of differing pore sizes on the biocompatibility of two polypropylene meshes in the repair of abdominal defects. Experimental study in dogs.

Two types of monofilament polypropylene meshes of markedly different construction, configuration and pore size were compared and used to repair full-thickness muscle defects in the abdominal wall of 22 mongrel dogs to assess their biocompatibility with host tissues. The defects were repaired with Prolene (Ethicon) woven mesh (pore size = 164 x 96 microns) and with an experimental, extruded mesh called T mesh (pore size = 3 mm x 4 mm). On the 30th postoperative day, the animals were sacrificed, and the segments of the abdominal wall containing the implanted meshes were excised. Although the Prolene mesh had greater tensile strength before implantation, 30 days after implantation, the T mesh showed similar tensile strength to Prolene mesh. The collagen densitometry showed a significant increase of total and mature collagen type I deposition in the T mesh. This suggests that the increased mature collagen type I deposition significantly increases the tensile strength of the reinforced mesh tissue and that the larger pore in the T mesh contributed to this finding by allowing increasing fibber orientation within the pores as a result of in vivo tension.

Abdominal Muscles↗
PubMed2000

Effects of interleukin-4 deprivation and treatment on resistance to Trypanosoma cruzi.

Trypanosoma cruzi (Y strain)-infected interleukin-4(-/-) (IL-4(-/-)) mice of strains 129/J, BALB/c, and C57BL/6 showed no significant difference in parasitemia levels or end point mortality rates compared to wild-type (WT) mice. Higher production of gamma interferon (IFN-gamma) by parasite antigen (Ag)-stimulated splenocytes was observed only for C57BL/6 IL-4(-/-) mice. Treatment of 129/J WT mice with recombinant IL-4 (rIL-4), rIL-10, anti-IL-4, and/or anti-IL-10 monoclonal antibodies (MAbs) did not modify parasitism. However, WT mice treated with rIL-4 and rIL-10 had markedly increased parasitism and suppressed IFN-gamma synthesis by spleen cells stimulated with parasite Ag, concanavalin A, or anti-CD3. Addition of anti-IL-4 MAbs to splenocyte cultures from infected WT 129/J, BALB/c, or C57BL/6 mice failed to modify IFN-gamma synthesis levels; in contrast, IL-10 neutralization increased IFN-gamma production and addition of rIL-4 and/or rIL-10 diminished IFN-gamma synthesis. We conclude that endogenous IL-4 is not a major determinant of susceptibility to Y strain T. cruzi infection but that IL-4 can, in association with IL-10, modulate IFN-gamma production and resistance.

Animals↗
PubMed1997

Cryptosporidium infection in infancy as a cause of malnutrition: a community study from Guinea-Bissau, west Africa.

Cryptosporidium parvum causes persistent diarrhea in young children in developing countries. To determine the interaction between nutritional status and cryptosporidiosis, an open cohort of 1064 children younger than 3 y of age was followed for 1441 child-years by weekly diarrhea recall visits. A total of 5072 weight and 4264 height measurements was made. There were no tendencies of low weight (P = 0.38) or height (P = 0.16) in children who acquired cryptosporidiosis. Cryptosporidiosis in infancy was accompanied by an estimated weight loss of 392 g (95% CI: 247, 538 g) in boys and 294 g (95% CI: 109, 479 g) in girls, corresponding to 3.7% and 2.9% of mean weight, respectively, at 2 y of age. No significant catch-up growth covered for this loss in weight. A similar effect in linear growth was shown (P = 0.02). Although it has been suggested that the effect of infections on nutrition is usually transient because of catch-up growth, the present study suggests that cryptosporidiosis in infancy has a permanent effect on growth.

Africa, Western↗
PubMed1994

Prolonged breast feeding, diarrhoeal disease, and survival of children in Guinea-Bissau.

OBJECTIVE: To analyse the impact of breast feeding on diarrhoeal disease and survival in children above 1 year of age in Guinea-Bissau, west Africa. DESIGN: A community study of an open cohort followed up weekly by interviews over 15 months. Data on feeding practices, anthropometry, and survival were recorded for three years. SETTING: 301 randomly selected houses in a semiurban area in the capital, Bissau. SUBJECTS: 849 children aged less than 3 years. MAIN OUTCOME MEASURES: Incidence and duration of diarrhoea, weight for age, and death of a child. RESULTS: The incidence of diarrhoea was higher in weaned children than in partially breast fed children, both in 1 year olds (relative risk 1.41; 95% confidence interval 1.23 to 1.62) and in 2 year olds (1.67; 1.29 to 2.15). The mean duration of an episode of diarrhoea was 5.3 days in breast fed children compared with 6.3 days in weaned children (P = 0.001). Independent of the age of weaning, a similar increase was found in an analysis comparing, for each child, the rate and duration of diarrhoea one month before and one month after weaning. Children with low weight for age were breast fed longer than the better nourished children (P = 0.02). Children aged 12-35 months who were not breast fed had a 3.5 times higher mortality (1.4 to 8.3) than breast fed children. CONCLUSIONS: The beneficial effects of breast feeding are not restricted to infancy. Though children who are partially breast fed after infancy may have a lower state of nutrition than the weaned ones, the benefit in terms of lower morbidity may be more important for child survival in places with a high morbidity from diarrhoea and with high mortality.

Age Factors↗
PubMed1994

Risk factors for Cryptosporidium diarrhea in early childhood: a case-control study from Guinea-Bissau, West Africa.

Cryptosporidium is increasingly recognized as an important agent of diarrhea in normal and immunocompromised humans. In young children in developing countries the parasite is a cause of persistent diarrhea with an associated excess mortality. To elucidate possible determinants of cryptosporidiosis, an open cohort of young children from a semiurban area of the capital of Guinea-Bissau was followed for 2 years. Data about possible risk factors were recorded each month, and a nested case-control study of 125 children with Cryptosporidium diarrhea and an equal number of matched controls was conducted. The following risk factors were identified by conditional multiple logistic regression: keeping of pigs (odds ratio (OR) = 2.5, 95% confidence interval (CI) 1.4-4.7) and dogs (OR = 2.1, 95% CI 1.0-4.2) in the household, storage of cooked food for later consumption (OR = 1.8, 95% CI 1.0-3.3), and child's sex (OR for boys = 1.9, 95% CI 1.0-3.4). Breast feeding was protective (OR = 0.3, 95% CI 0.1-1.1). The findings provide clues for interventions against this major cause of childhood diarrhea and give suggestions for further studies.

Animals↗
PubMed1994

The etiology of early childhood diarrhea: a community study from Guinea-Bissau.

A potential enteropathogen was found in 50% of 1219 diarrheal episodes and 48% of 511 asymptomatic controls in a 1-year community study of childhood diarrhea. Rotavirus (3% of episodes), Cryptosporidium species (6%), and enteropathogenic Escherichia coli (EPEC) with EPEC adherence factor (4%) were more prevalent in cases than controls. Giardia lamblia (19%) was the most prevalent organism but was not associated with diarrhea. Enterotoxigenic E. coli (12%), Strongyloides stercoralis (5%), Shigella species (2%), Entamoeba histolytica trophozoites (2%), and Vibrio cholerae (1%) were found at nonsignificantly higher rates. Salmonella and Campylobacter species were more prevalent among control infants. Cryptosporidium species and sequential infections from other pathogens caused persistent diarrhea.

Child↗
PubMed1994

Immunosuppression after measles vaccination.

The influence of conventional live attenuated measles vaccine on cellular immune responsiveness was investigated in Sweden and Guinea-Bissau. Sixteen children in a residential area in Bissau and 16 living in southern Stockholm were examined before and 8-10 days after vaccination. Lymphoproliferation was measured to concanavalin A (con-A), PPD and tetanus toxoid (TT) using a whole-blood 3H-thymidine incorporation assay. Stimulation indices were significantly lower after vaccination than before, in the case of con-A (p = 0.03) and TT (p = 0.01) in the Guinean children and in the case of PPD (p = 0.009) and TT (p = 0.03) in the Swedish children. Stimulation of lymphocytes from measles-immune children with measles antigens resulted in weak lymphoproliferative responses. These observations may be relevant to the increased mortality found in children immunized with high-titre measles vaccines, as compared to controls, in recent studies. The study confirms the applicability and usefulness under field conditions of the whole blood version of the thymidine incorporation assay.

Child, Preschool↗
PubMed1993

Cryptosporidiosis in infancy and childhood mortality in Guinea Bissau, west Africa.

OBJECTIVE: To investigate the epidemiology of and mortality from cryptosporidiosis in young children in Guinea Bissau, West Africa. DESIGN: Three year community study of an open cohort followed up weekly. SETTING: 301 randomly selected houses in a semi-urban area in the capital, Bissau. SUBJECTS: 1315 children aged less than 4 years. MAIN OUTCOME MEASURES: Cryptosporidium infection detected by examination of stools during episode of diarrhoea and death of a child. RESULTS: Cryptosporidium spp were found in 239 (7.4%) out of 3215 episodes of diarrhoea. The parasite was most common in younger children (median age 12 months) and at the beginning of the rainy seasons. The prevalence of cryptosporidiosis was 15% (77/513) in cases of persistent diarrhoea compared with 6.1% (148/2428) in diarrhoea lasting less than two weeks (p < 0.0001). Cryptosporidiosis was associated with excess mortality in children who had the infection in infancy, and this excess mortality persisted into the second year of life (relative mortality 2.9 (95% confidence interval 1.7 to 4.9)). The excess mortality could not be explained by malnutrition, or by socioeconomic factors, hygienic conditions, or breast feeding. CONCLUSIONS: Cryptosporidiosis is an important cause of death in otherwise healthy children in developing countries.

Child, Preschool↗
PubMed1993

[Selenium. Its physiologic and clinical importance].

Since its discovery in 1817, Selenium has had great biological importance as a key element of cellular protection and in its absence of pathological symptoms. In this revised work, historical aspects of selenium are considered, its characteristics, properties and source as well as its nutritional value, metabolism, physiopathological and biochemical function in humans and finally its future therapeutical application in humans and animals considering some of the traditional ways of treatment.

Humans↗
PubMed1991

Risk factors for HIV-2 infection in Guinea-Bissau.

To define the epidemiology of HIV-2 infection, we conducted a case-control study among hospitalized patients at an acute care hospital in Bissau, Guinea-Bissau, a country with endemic HIV-2 infection. Among 128 patients with various diagnoses, 23 (18%) were positive for HIV-2 by ELISA and Western blot. One of these patients was serologically reactive for HIV-1 also, but PCR and viral culture revealed the presence of HIV-2 only. To study risk factors, behaviors, and AIDS knowledge related to the acquisition of HIV infection, 22 HIV-2-seropositive and 21 seronegative hospitalized patients were given a physical examination and administered a questionnaire. Among women, transfusion was associated with HIV-2 infection (OR = 14.4, p = 0.02); among men, sex with a prostitute was the principal risk factor (OR = undefined, p = 0.02). Although 79% of HIV-infected patients and controls had heard of AIDS, only 17% of all study participants and 50% of males reporting sex with prostitutes had used condoms in the previous year. These data suggest that the risk factors for HIV-2 infection are similar to those for HIV-1 and support previous studies showing that HIV-2 is the predominant HIV in Guinea-Bissau. Efforts to decrease transmission of HIV-2 should include screening for HIV-2 in blood for transfusion in endemic areas (now done in Bissau) and education about the risk of sexual transmission.

Adolescent↗