PubMed Health⌕ Search

Biomedical subjects

M A da Silva

Publications and source records attributed to M A da Silva.

At least 19 recordsLinked to original sources
PubMed2004

Flavonoids and antiulcerogenic activity from Byrsonima crassa leaves extracts.

Byrsonima crassa Niedenzu (IK) (Malpighiaceae) is used in Brazilian folk medicine for the treatment of diseases related mainly to gastric ulcers. In this study, we evaluated the potential antiulcerogenic effect of three different extracts obtained from the leaves of Byrsonima crassa namely hydromethanolic (80% MeOH), methanolic (MeOH) and chloroformic extracts (CHCl(3)). The oral administration (250, 500 and 1000 mg/kg) of all the extracts reduced the formation of lesions associated with HCl/ethanol administration in mice. The 80% MeOH extract significantly reduced the incidence of gastric lesions by 74, 78 and 92% at doses of 250, 500 and 1000 mg/kg, respectively (P<0.01). The MeOH extract reduced the ulceration by 93 and 99% only at the doses of 500 and 1000 mg/kg (P<0.01). The lower gastroprotective action (69%) was observed when animals were treated with CHCl(3) extract at the dose of 1000 mg/kg (P<0.01). Phytochemical investigation of Byrsonima crassa afforded five known substances: quercetin-3-O-beta-d-galactopyranoside, quercetin-3-O-alpha-l-arabinopyranoside, the biflavonoid amentoflavone, (+)-catechin and (-)-epicatechin. The presence of these phenolic compounds may probably explain the antiulcerogenic effect of the extracts of Byrsonima crassa leaves.

Animals↗
PubMed2001

Evaluation of the effect of 90Sr beta-radiation on human blood cells by chromosome aberration and single cell gel electrophoresis (comet assay) analysis.

Among various environmental genotoxins, ionizing radiation has received special attention because of its mutagenic, carcinogenic and teratogenic potential. In this context and considering the scarcity of literature data, the objective of the present study was to evaluate the effect of 90Sr beta-radiation on human cells. Blood cells from five healthy donors were irradiated in vitro with doses of 0.2-5.0Gy from a 90Sr source (0.2Gy/min) and processed for chromosome aberration analysis and for comet assay. The cytogenetic results showed that the most frequently found aberration types were acentric fragments, double minutes and dicentrics. The alpha and beta coefficients of the linear-quadratic model, that best fitted the data obtained, showed that 90Sr beta-radiation was less efficient in inducing chromosome aberrations than other types of low linear energy transfer (LET) radiation such as 3H beta-particles, 60Co gamma-rays, 137Cs and 192Ir and X-rays. Apparently, 90Sr beta-radiation in the dose range investigated had no effect on the modal chromosome number of irradiated cells or on cell cycle kinetics. Concerning the comet assay, there was an increase in DNA migration as a function of radiation dose as evaluated by an image analysis system (tail moment) or by visual classification (DNA damage). The dose-response relation adequately fitted the non-linear regression model. In contrast to the cytogenetic data, 90Sr beta-radiation induced more DNA damage than 60Co gamma-radiation when the material was analyzed immediately after exposures. A possible influence of selective death of cells damaged by radiation was suggested.

Adult↗
PubMed2001

A single strain of Mycobacterium bovis bacillus Calmette-Guérin (BCG) grown in two different media evokes distinct humoral immune responses in mice.

Two attenuated bacillus Calmette-Guérin (BCG) preparations derived from the same Moreau strain, Copenhagen but grown in Sauton medium containing starch and bacto-peptone (onco BCG, O-BCG), or asparagine (intradermal BCG, ID-BCG), exhibited indistinguishable DNA sequences and bacterial morphology. The number of viable bacilli recovered from spleen, liver and lungs was approximately the same in mice inoculated with the vaccines and was similarly reduced (over 90%) in mice previously immunized with either BCG vaccine. The humoral immune response evoked by the vaccines was, however, distinct. Spleen cell proliferation accompanying the growth of bacilli in tissue was significantly higher in mice inoculated with O-BCG. These cells proliferated in vitro upon challenge with the corresponding BCG extract. Previous cell treatment with mAb anti-CD4 T cells abolished this effect. Anti-BCG antibodies, as assayed either in serum by ELISA or by determining the number of antibody-producing spleen cells by the spot-ELISA method, were significantly higher in mice inoculated with ID-BCG. Anti-BCG antibodies were detected in all immunoglobulin classes, but they were more prevalent in IgG with the following distribution among its isotypes: IgG1>(IgG2a = IgG2b)>IgG3. When some well-characterized Mycobacterium tuberculosis antigens were used as substitutes for BCG extracts in ELISA, although antibodies against the 65-kDa and 96-kDa proteins were detected significantly, antibodies against the 71-kDa, 38-kDa proteins and lipoarabinomannan were only barely detected or even absent. These results indicate that BCG bacilli cultured in Sauton-asparagine medium permitted the multiplication of bacilli, tending to induce a stronger humoral immune response as compared with bacilli grown in Sauton-starch/bacto-peptone-enriched medium.

Animals↗
PubMed2001

Evaluation of radioinduced damage and repair capacity in blood lymphocytes of breast cancer patients.

Genetic damage caused by ionizing radiation and repair capacity of blood lymphocytes from 3 breast cancer patients and 3 healthy donors were investigated using the comet assay. The comets were analyzed by two parameters: comet tail length and visual classification. Blood samples from the donors were irradiated in vitro with a 60Co source at a dose rate of 0.722 Gy/min, with a dose range of 0.2 to 4.0 Gy and analyzed immediately after the procedure and 3 and 24 h later. The basal level of damage and the radioinduced damage were higher in lymphocytes from breast cancer patients than in lymphocytes from healthy donors. The radioinduced damage showed that the two groups had a similar response when analyzed immediately after the irradiations. Therefore, while the healthy donors presented a considerable reduction of damage after 3 h, the patients had a higher residual damage even 24 h after exposure. The repair capacity of blood lymphocytes from the patients was slower than that of lymphocytes from healthy donors. The possible influence of age, disease stage and mutations in the BRCA1 and BRCA2 genes are discussed. Both parameters adopted proved to be sensitive and reproducible: the dose-response curves for DNA migration can be used not only for the analysis of cellular response but also for monitoring therapeutic interventions. Lymphocytes from the breast cancer patients presented an initial radiosensitivity similar to that of healthy subjects but a deficient repair mechanism made them more vulnerable to the genotoxic action of ionizing radiation. However, since lymphocytes from only 3 patients and 3 normal subjects were analyzed in the present paper, additional donors will be necessary for a more accurate evaluation.

Adult↗
PubMed1999

Active alpha-glucoside transport in Saccharomyces cerevisiae.

The AGT1 permease is a alpha-glucoside-H+ symporter responsible for the active transport of maltose, trehalose, maltotriose, alpha-methylglucoside, melezitose and sucrose. In wild-type as well as in MAL constitutive strains, alpha-methylglucoside seemed to be the best inducer of transport activity, while trehalose had no inducing effect. Based on the initial rates of transport it seems that the sugar preferentially transported by this permease is trehalose, followed by sucrose.

Biological Transport, Active↗
PubMed1999

[Prevalence of serologic markers of hepatitis B virus in hospital personnel].

OBJECTIVE: To verify the prevalence of the anti-HBc, anti-HBs and HBsAg markers of hepatitis B virus, and to identify the risk factors determining occupational infection with this virus among hospital personnel. METHODS: Samples of serum from 210 persons both male and female who work in different occupations at a hospital university, were analysed. The technique employed was the immunoenzymatic assay using commercial kits. RESULTS: As a control group, samples of serum from 45 volunteer blood donors were utilized. It was verified that 20.5% of the hospital personnel presented a positive reaction to at least one of the markers songht, as against 6.6% of the control group. The prevalence of each marker separately was: anti-HBc 8.1%, anti-HBs 5.2%, and HBsAg 2.9% in the hospital personnel; and 4.4%, 2.2% and 0.0% in the control group. The simultaneous presence of the anti-HBc and anti-HBs markers was detected in 4.3% of the workers. In the control group, the presence of the anti-HBc and anti-HBs markers was detected, isolately, with respective prevalences of 4.4% and 2.2%. Those who presented the highest rates of positivite reaction were: laboratory technicians 24.0%, nurses 23.6%, physicians 20.8%, and cleaning personnel 18.2%. CONCLUSIONS: The findings suggest that direct contact with patients and handling of blood and other body fluids are risk factors related to occupational infection with HBV. Therefore, it is recommended that hospital personnel be vaccinated against hepatitis B.

Adult↗
PubMed1998

[Myocardial revascularization surgery via a left minithoracotomy].

PURPOSE: There is, today, a global tendency towards a surgical approach privileging very small incisions, the so-called minimally invasive intervention, which results in a less aggressive action. The introduction of this new technique makes it possible to dissect the left internal thoracic artery (LITA) and to perform in the anastomosis with the anterior interventricular artery (AIA) through a left minithoracotomy. METHODS: From May of 1996 to october of 1997, 11 patients with ischemic heart disease and a single proximal lesion of the AIA were submitted to a myocardial revascularization (MR). The surgical approach consisted of a left anterolateral thoracotomy through the 4th left intercostal space, of approximately 10 cm, and in the last 6 cases, resection of part of the cartilage of the 4th and 5th ribs, dissection of the LITA, as well as opening and repair of the pericardium adjacent to the AIA was done. All patients received a single bypass to the AIA with a graft of the LITA, without extracorporeal circulation. RESULTS: The patients' age varied between 46 and 76 years (mean = 58.55). Ten patients (90.90%) were males and 1 (9.09%) was a female. Hospital stay ranged from 4 to 8 days, with the average of 5.2 days. None of the patients presented any electrocardiographic change in the immediate post-operatory period. During the control period one patient developed a clot in the distal LITA, with important compromise of the flow. In another patient the stenosis was at the level of the anastomosis. Both were successfully submitted to angioplasty. There were no deaths in the groups studied. CONCLUSION: The absence of deaths suggests to us that MR surgery carried out with this minimally invasive technique, in selected groups and is an excellent alternative to the revascularization of the AIA.

Aged↗
PubMed1998

[Risk factors for acute myocardial infarction in Brazil. FRICAS Study].

PURPOSE: To determine risk factors related to acute myocardial infarction (AMI) in Brazil. METHODS: Five hundred ninety one patients were selected in 20 medical centers in Brazil, between January/94 and March/95. Two-hundred-ninety-nine patients were cases, and 292 controls with a variety of acute diseases not related to the suspected or known risk factors for acute myocardial infarction. All data were collected through a structured questionnaire filled by the patients. The evaluation of the variables was done through univariate analysis with a significance level of 5%. RESULTS: The factors related to acute myocardial infarction were respectively to cases and controls: Hypercholesterolemia--210.93 +/- 46.74 mg/dl and 185.71 +/- 45.45 mg/dl, (p = 0.000); smoking--41.69% and 27.20% (p = 0.000); hypertension--52.35% and 20.88% (p = 0.000); diabetes--19.70% and 9.93% (p = 0.001); family history--related to the patient's father in 42.14% and 33.22% (p = 0.025) and to the mother in 42.14% and 30.82% (p = 0.007); socioeconomic level--88.99% and 60.20% owned house (p = 0.002); 44.45% and 33.21% owned car (p = 0.010); physical activity--56.83% and 48.28% had the habit of walking in the year prior to study entry (p = 0.029); diet--38.79% and 28.42% consumed canned food (p = 0.013). The mean weight was 72.50 +/- 26.89 kg and 69 +/- 12.26 kg (p = 0.0271). The mean height was 166.56 +/- 8.81 cm and 166.66 +/- 8.47 cm. CONCLUSION: This study confirmed the importance of hypercholesterolemia, hypertension, diabetes mellitus, overweight and family history as risk factors for acute myocardial infarction. There was a significant relation between socioeconomic level and the prevalence of acute myocardial infarction.

Adult↗
PubMed1998

European guidelines for quality assurance in the surgical management of mammographically detected lesions. European Breast Cancer Working Group.

The European Guidelines developed for mammography screening have contributed to the general discussion on quality assurance and the important tasks of the health professionals dealing with breast cancer screening. The cooperation of each medical discipline is of utmost importance in order to achieve optimal results and eventually a mortality reduction. The following guidelines are based on the British NHS quality assurance guidelines for surgeons in breast cancer screening and modified to meet the different needs in the European Countries. The term "surgeon" denotes a medical doctor trained and involved in the surgical treatment of breast diseases. The members of the working group who participated in order to adapt these guidelines are listed above. We hope that this document will contribute towards a more comprehensive approach of breast cancer screening-detected lesions throughout Europe.

Breast Neoplasms↗
PubMed1997

Cellular signalling of PCH-induced pigment aggregation in the crustacean Macrobrachium potiuna erythrophores.

The cellular system responsible for the transduction of the pigment-concentrating hormone (PCH) signal was investigated in erythrophores of the freshwater shrimp, Macrobrachium potiuna. Dose-response curves to the hormone were determined in the absence and in the presence of several drugs that affect sequential steps of the Ca(2+)-dependent signalling pathway. Additionally, the ability of forskolin to induce pigment dispersion was evaluated. Neomycin sulphate (10(-4) and 10(-3) mol.l-1), trifluoperazine (10(-5) and 10(-4) mol.l-1), 1-(5-isoquinolinesulfonlyl)-2-methylpiperazine (10(-7) and 10(-5) mol.l-1) and okadaic acid (10(-7) mol.l-1) significantly (P < 0.05) decreased the responses to PCH. However, okadaic acid at low concentration (10(-9) mol.l-1) and cyclosporin A (10(-6) and 10(-5) mol.l-1) did not significantly (P > 0.05) affect PCH activity. Forskolin (10(-4) mol.l-1) was able to half-maximally reverse the hormone-induced aggregation. Our results suggest that the pigment-concentrating hormone induces pigment aggregation through a Ca(2+)-dependent pathway with a posteriori phosphatase activation, probably the serine/threonine phosphatase 1.

1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine↗
PubMed1996

Isolation and in vitro hydrolysis of lentil protein fractions by trypsin.

The albumin and globulin fractions from lentil seeds were isolated and characterised by gel filtration. The latter was shown to be homogeneous and the former heterogeneous on PAGE. The amino acid analysis revealed high values of amidic amino acids for both fractions with great differences in the sulphur-containing amino acids. Native albumin, globulin and salt-soluble proteins were markedly resistant to trypsin hydrolysis compared to casein. The SDS-PAGE of native salt-soluble proteins indicated that the globulin fragments (20 to 30 kD) were slowly digested in the presence of albumin. The heating increased the hydrolysis of the proteins in the order: salt-soluble, albumin and globulin. The facilitated hydrolysis of the heated salt-soluble fraction seemed to be due to protein-protein interactions induced by heat.

Fabaceae↗
PubMed1994

[Chronic phase of Chagas disease. Clinical aspects and course of the disease].

PURPOSE: To evaluate the clinical and evolutive aspects of chronic chagasic patients. METHODS: Three hundred chronic chagasic patients, 180 females, with age ranging from 19 to 81 years (55.6 +/- 13.1) were retrospectively studied. Patients were divided according to the following clinical types: indeterminated, cardiac (with the subtypes: arrhythmogenic, dilated and mixed), digestive isolated and digestive plus cardiac involvement. The following variables were analysed: prevalence of each clinical forms, symptoms, electrocardiographic pattern and clinical outcome. RESULTS: At the start of the study, 73 (24.3%) patients were in indetermined type, 106 (35.3%) in cardiac arrhythmogenic, 95 (31.6%) in mixed, 7 (2.3%) in dilated, 16 (5.3%) in digestive plus cardiac type and 3 (1%) in the pure digestive type. The most prevalent symptoms were dyspnea on efforts (57%), palpitations (41.33%) and chest pain (33%). The most frequent electrocardiographic pattern was right bundle branch block plus antero-superior fascicular block, in 30% of the patients. The average follow-up time was 7.8 +/- 6.1 years and the outcome was considered good in 20 patients (6.6%), stable in 214 (71.3%) and bad in 66 (23%). At the end of the follow-up, 9 patients have evaluated from the indeterminated to the cardiac and digestive types, and 19 (17.92%), from the arrhythmogenic to mixed cardiac subtype. The follow-up was lost in 79 patients (26.3%), most of them, probably dead. CONCLUSION: With a mean time of 7.8 years, 12.3% of the patients in the indeterminated type evolved to the cardiac and/or digestive type; right brundle branch block with antero-superior fascicular block was the most prevalent electrocardiographic pattern; the outcome was stable or good in the majority of these patients.

Adult↗