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Biomedical subjects

J Barreto

Publications and source records attributed to J Barreto.

63 records · Page 4Linked to original sources
PubMed1994

The influence of Maloprim chemoprophylaxis on cellular and humoral immune responses to Plasmodium falciparum asexual blood stage antigens in schoolchildren living in a malaria endemic area of Mozambique.

We examined the impact of chemoprophylaxis on the cellular and humoral immune responses to polypeptides of the asexual Plasmodium falciparum blood stage antigens, the glutamate rich protein GLURP and Pf155/RESA, both of which in previous field studies have been identified as potentially protective antigens. The study was carried out in the Escola Primária de Lingamo, a primary school in a suburban area of Maputo, Mozambique. A cohort of 392 schoolchildren (aged 7-12 years) was randomly allocated to two equal groups, one receiving chemoprophylaxis with dapsone/pyrimethamine (Maloprim), the other receiving placebo every week from December 1989 to November 1990. The groups were then followed until November 1991 without chemoprophylaxis. Cellular responses to immunodominant epitopes from Pf155/RESA and GLURP, and to non malaria antigens C. albicans and PPD, were assessed by lymphocyte proliferation assays in vitro. Anti-GLURP and anti-Pf155/RESA antibodies were detected by enzyme-linked immunosorbent assay (ELISA) and erythrocyte membrane immunofluorescence (EMIF), and total anti-P. falciparum antibodies were measured by indirect fluorescent antibody test (IFAT). Immunological reactivities were evaluated every six months, at the end of the rainy season and at the end of the dry season, both during the period of chemoprophylaxis and during the follow-up. The antibody response rate to the GLURP was lower in the Maloprim group than in the placebo group during the intervention phase. The lymphoproliferative response rate to the malaria antigens was significantly lower at the end of the rainy season than at the end of the dry season, but the difference between the experimental group and the control group of schoolchildren was not statistically significant. These results suggest that the antibody responses to the GLURP molecule and partly to the Pf155/RESA antigen in this study population were shortlived and dependent on frequent boostering, but whether these antigens play a role in the development of natural clinical immunity remains open. In the experimental group of schoolchildren weekly chemoprophylaxis successfully reduced the parasite rate during the rainy season from 43% to 4%, and during the dry season from 18% to 0%. Chemoprophylaxis may therefore have a useful role in combination with another partially effective malaria control measure such as insecticide-impregnated bed nets or a malaria vaccine.

Animals↗
PubMed1993

Pathologic features of epidermoid carcinoma of the penis. A prospective study of 66 cases.

We report a whole-organ-section pathologic study of 66 cases of epidermoid carcinoma of the penis. Specimens were divided into three compartments: glans (G), coronal sulcus (COS), and foreskin (F) with 24, 4, and 12 histologic sections each. Four types of carcinomas were found: (a) superficially spreading (42%), a biphasic infiltrating and extensive carcinoma in situ usually involving more than one compartment and radially growing along the surface of G, BPS, F, or even urethra; (b) vertical growth (32%), unifocal high-grade, deeply invasive neoplasms with minimal or no carcinoma in situ component; (c) verrucous (18%), low-grade papillary or endophytic; and (d) multicentric (8%), two or more independent primary tumors separated by non-neoplastic mucosa. Inguinal lymph node metastasis were found in 82, 42, and 33% of pathologic types vertical growth, superficially spreading, and multicentric carcinomas, respectively; verrucous tumors did not show metastasis. The morphologic diversity of penile cancer may be related to different causative factors. Metastatic involvement suggests a distinctive biological behavior of the tumor. The widespread extension of superficially spreading and multicentric carcinomas to anatomical compartments indicate penile mucosa as one "field" prone to malignant transformation. These findings may be important for the selection of appropriate therapy and emphasize the need for a close follow-up of patients undergoing less than a complete removal of the three compartments.

Carcinoma, Squamous Cell↗
PubMed1993

High prevalence of sexually transmitted diseases in a rural area in Mozambique.

OBJECTIVE: To assess the extent of the sexually transmitted diseases (STDs) problem in a rural area of Mozambique. METHODS: A cross sectional study among pregnant women and patients presenting with genital complaints. Laboratory confirmation was done for gonorrhoea, chlamydial infection, active syphilis, trichomoniasis and HIV infection. SETTING: A primary health care setting in Vilanculos, Inhambane province, Mozambique. RESULTS: Evidence of one or more of the above STDs was found in 51% of 201 pregnant women, 56% of 85 women and 62% of 77 men with genital complaints. Neisseria gonorrhoea or Chlamydia trachomatis were found in 16% of pregnant women, 23% of female patients and 28% of male patients; genital ulcer disease was present in 6%, 28% and 36%, of respectively pregnant women, female and male patients. The prevalence of active syphilis was about the same in the three groups of study subjects, that is 15%. HIV infection was found in 4% of the male patients; no HIV infection could be detected in the female groups. CONCLUSION: STDs were a major health problem in this rural area in Mozambique. Though HIV infection was still low, the high prevalence of STDs indicates that the potential is there for an explosive spread of the HIV/AIDS epidemic.

Adolescent↗
PubMed1993

HIV-1 and HIV-2 antibodies in pregnant women in the City of Maputo, Mozambique. A comparative study between 1982/1983 and 1990.

The seroprevalence of HIV-1 and HIV-2 among pregnant women in Maputo, the capital of Mozambique, was compared between the years 1982/83, 1988 and 1990. None of the 432 serum samples collected in 1982/83 was positive for HIV antibodies whereas in 1988 the HIV-1 and HIV-2 seroprevalence was 0.4% (2/500) and 0.6% (3/500), respectively, and in 1990 0.6% (12/2014) and 0.2% (4/2014), respectively. These results indicate that HIV infection has been introduced recently in Maputo and is spreading at a slow rate among women.

Adolescent↗
PubMed1992

Vesicle acidification driven by a millionfold proton gradient: a model for acid influx through gastric cell membranes.

A delta pH 6 proton (internal pH 7.5, external pH 1.5) was imposed across the bilayer of egg phosphatidylcholine (PC) vesicles. The presence of the gradient was verified by the use of agents that predictably collapsed it. These agents included a detergent (Triton X-100), a pore-forming Na-H+ exchanger (nigericin), and weak acids capable of shuttling protons across the membrane (acetic and acetylsalicylic acids). The magnitude of the proton gradient and the rate of pH gradient collapse were determined by measuring pyranine fluorescence by use of an isosbestic point technique and calculating intravesicular pH from a calibration curve. Acid flux into the vesicles in the presence of chloride was measured directly by a simpler one-wavelength method. p-Xylene-bis-pyridinium bromide (DPX), a pyranine fluorescence quencher, was used to verify that the fluorescence signal originated from within the vesicles and that the observed rates of acidification were not an artifact due to pyranine leakage. Acid flux was found to be dependent on the ionic composition of the buffer. The presence of chloride ion in the external compartment caused a dramatic increase in the rate of acidification. It was demonstrated that the kinetics of acid flux into the vesicle were clearly controlled by the chloride-dependent mechanism at a relatively low chloride concentration of 2.5 mM. The model presented here is a simple and sensitive method for investigating the factors that influence acidification rates across membranes when acidification is driven by extremely large proton gradients, in the presence of chloride; conditions similar to those found in the stomach.

Acids↗
PubMed1991

Simultaneous carcinoma involving the endometrium and the ovary. A clinicopathologic, immunohistochemical, and DNA flow cytometric study of 18 cases.

Eighteen carcinomas involving both the endometrium and the ovary were studied. Stage, size, bilaterality and pattern of ovarian involvement, histologic types and grades, presence of endometrial hyperplasia or ovarian endometriosis, myometrial, tubal, lymphatic and blood vessel invasion, and follow-up of the patients were all evaluated. Accordingly, the cases were classified as follows: Group A (nine cases), two separate primary tumors; and Group B (nine cases), uterine primaries with ovarian metastasis or ovarian primaries with uterine metastasis. Immunohistochemical stains (CAM 5.2, wide-spectrum keratin, vimentin, carcinoembryonic antigen (CEA), CA 12.5, CA 19.9) were performed in all cases. Flow cytometric determination of nuclear DNA was done in 13 (seven Group A and six Group B tumors). Of the nine cases with independent primary tumors, seven showed different immunohistochemical profiles in the ovarian and uterine tumors, whereas only four of the nine metastatic ones had similar staining characteristics. Five cases with independent primary tumors, but only one of the metastatic group, exhibited different aneuploid stemlines in the endometrial and ovarian tumors. The other seven (two independent and five metastatic) cases had similar DNA indexes in both tumors. Immunohistochemical and DNA flow cytometric study may be of some value for the distinction between metastatic and independent tumors, but differential diagnosis must presently rely largely upon conventional clinicopathologic criteria.

Adenocarcinoma↗