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Biomedical subjects

A Alves

Publications and source records attributed to A Alves.

At least 55 records · Page 3Linked to original sources
PubMed2000

Multi-residue methodology for pesticide screening in wines.

A multi-residue solid-phase microextraction/gas chromatography/electron-capture detection method for pesticide screening (nine organochlorine, eleven organophosphorous and a tiadiazine insecticides, a benzoylurea acaricide and a halogenated sulfamide fungicide) in wine was developed. Fiber coating, extraction time and temperature, exposure of the fiber to the headspace or to the liquid phase and the ethanol effect on pesticides extraction were the parameters studied. The best results were obtained for a 100 microm poly(dimethylsiloxane) fiber, with 30 min immersion, in a 3 ml sample, at 45 degrees C. Pesticides extraction yield from aqueous spiked solutions was studied, for different ethanol concentrations (9%, 12.5% and 20%, v/v), which are representative of the main types of Portuguese wines. Calibration curves for extracted standards gave linear responses for all the pesticides, except dichlorvos, mevinphos, disulfoton and methidathion. Average detection limits were lower than 5 ppb and no significant interference from the matrix was found in the conditions studied, except for buprofezin.

Chromatography, Gas↗
PubMed2000

Biomaterial-induced sarcoma: A novel model to study preneoplastic change.

In the study of carcinogenesis most interest has focused on carcinomas, as they represent the majority of human cancers. The recognition of the adenoma-carcinoma sequence both in humans and in animal experimental models has given the field of basic oncology the opportunity to elucidate individual mechanisms in the multistep development of carcinoma. The relative scarcity of human sarcomas coupled with the lack of adequate animal models has hampered understanding of the molecular genetic steps involved. We present an experimental model in the rat in which a high incidence of malignant mesenchymal tumors arise around a subcutaneously implanted biomaterial. Nine commercially available biomaterials were implanted in a total of 490 rats of the Fischer strain for 2 years. On average, macroscopic tumors were found in 25.8% of implantation sites over a period from 26 to 110 weeks after implantation. The most frequent tumors were malignant fibrous histiocytomas and pleomorphic sarcomas, although fibrosarcomas, leiomyosarcomas, and angiosarcomas readily developed, the latter especially around polyurethane implants. Of particular interest are the results of a detailed histological study of the capsules around the implanted biomaterials without tumors. Here a spectrum of change from focal proliferative lesions through preneoplastic proliferation to incipient sarcoma could be observed. A parallel immunohistochemical study of peri-implant capsules showed that proliferating cell nuclear antigen was of particular help in identifying these atypical proliferative lesions. To our knowledge this is the first description of a sarcoma model in which preneoplastic lesions can be readily identified and also reproducibly induced. This model provides the molecular biologist with defined stages in the development of mesenchymal malignancy, with which the multistage tumorigenesis hypothesis can be tested, analogous to the well-known adenoma-carcinoma sequence.

Animals↗
PubMed2000

Impact of obesity on surgical outcomes after colorectal resection.

BACKGROUND: As the impact of obesity on surgical outcomes after colorectal resection is not well known, this study was designed to compare the results of colorectal resection in obese and nonobese patients. METHODS: From 1990 to 1997, 584 consecutive patients underwent elective colorectal resection in our department. Of these, 158 (27%) were obese (body mass index >27). Obese and nonobese patients were well matched for demographic data and surgical procedures. RESULTS: After right or left colectomy, no difference was noted between obese and nonobese patients for overall mortality, morbidity, or leakage rates. However, after left colectomy, postoperative intra-abdominal collections requiring treatment were significantly more frequent in obese than in nonobese patients (10% versus 2%; P <0.05). After proctectomy, the mortality rate was 5% (3 of 61) among obese patients and 0.5% (1 of 185) among nonobese patients (P <0.02). The anastomotic leakage rate was 16% (5 of 58) for obese patients and 6% (11 of 169) for nonobese patients (P <0. 05), and the corresponding proportions of transfused patients were 43% and 19%, respectively (P <0.02). After proctectomy, multivariate analysis showed that for obese patients, diabetes mellitus (P <0.05) and American Society of Anesthesiologists (ASA) status >2 (P <0.05) were significant risk factors for anastomotic leakage; age >60 years (P <0.01) and ASA status >2 (P <0.05) were significant risk factors for perioperative blood transfusions. CONCLUSIONS: Our study suggested that, for obese patients, (1) right colectomy can be performed in the same manner as for nonobese patients; (2) after left colectomy, abdominal drainage may be indicated, and (3) after proctectomy, a defunctioning stoma should be recommended when diabetes mellitus or ASA status >2 is present, and an autologous blood transfusion could be discussed for patients >60 years old or with ASA status >2.

Aged↗
PubMed2000

[Gene therapy of liver tumors].

Gene therapy is a new therapeutic option for liver tumors which has been evaluated in animal models. The liver has characteristic features particularly interesting for gene transfer. Because of the rapid tumor growth within a quiescent parenchyma, retroviral transfer could express selective tropism. Temporary anatomic vascular exclusion would allow selective perfusion of the liver and avoid extrahepatic diffusion of the gene therapy. The early results have been promising in the animal. Clinical studies are currently under way in patients with liver metastasis from colorectal cancer.

Adenoviridae↗
PubMed1999

Laparoscopic Heller's cardiomyotomy in achalasia. Is intraoperative endoscopy useful, and why?

BACKGROUND: Inappropriate length of the myotomy incision along the stomach, the most common technical fault during Heller's cardiomyotomy, is related to the difficulty of identifying the gastro-esophageal junction, in particular during laparoscopic surgery. The goal of this study was to evaluate the contribution of endoscopy to gastro-esophageal junction identification during laparoscopic Heller's cardiomyotomy. METHODS: In a group of 19 patients with intraoperative endoscopy with laparoscopic Heller's cardiomyotomy, surgical and endoscopic criteria for gastro-esophageal junction identification have been assessed. Then postoperative results of this group were compared with those of another group of 16 patients previously operated on without intraoperative endoscopy. RESULTS: Endoscopic and laparoscopic criteria for gastro-esophageal junction identification were discordant in 11 patients (11/19, 58%). The cardia was in all these cases at a more distal site with endoscopic criteria. Complications ascribable to suboptimal technique were more frequent in the group without intraoperative endoscopy (7/16 patients) than in the other group (2/19 patients). CONCLUSIONS: Endoscopy during laparoscopic Heller's cardiomyotomy is of great assistance in identifying the cardia, and thereby could improve surgical outcomes.

Cardia↗
PubMed1999

Management of anastomotic leakage after nondiverted large bowel resection.

BACKGROUND: The purpose of this study was to determine the natural history of anastomotic leakage after elective colorectal resection and supraperitoneal anastomosis without temporary stoma. STUDY DESIGN: Medical records from 1990 to 1997 were studied; 655 consecutive patients underwent colonic or rectal resection (without stoma). Patients were divided into two groups: those with clinical anastomotic leakage confirmed by laparotomy (group 1) and those without anastomotic leakage (group 2). Postoperative clinical and biologic findings were compared between the two groups. RESULTS: Anastomotic leakage occurred in 39 of 655 patients (6%). Clinically suspected anastomotic leakage was only confirmed by contrast radiography in 13 of 24 patients (54%), and by CT in 8 of 9 patients (89%). Significantly more patients in group 1 than group 2 had the following: fever (> 38 degrees C) on day 2 (p < 0.001); absence of bowel action on day 4 (p < 0.001); diarrhea before day 7 (p < 0.001); collection of more than 400 mL of fluid through abdominal drains from day 0 to day 3 (p < 0.01); renal failure on day 3 (p < 0.02); and leukocytosis after day 7 (p < 0.02). Among the 39 patients in group 1, 28 (71%) had at least one of these clinical or biologic manifestations before day 5, but the mean delay for reoperation was only 8 days. The combination of signs observed before day 5 was associated with an increased risk of anastomotic leakage, from 18% with two signs to 67% with three signs. Overall mortality rate was 2% (13 of 655) and was significantly higher in group 1 than group 2: 5 of 39 (13%) versus 8 of 616 (1%, p < 0.001). In patients with anastomotic leakage, death occurred in 5 of 23 patients (22%) reoperated on after day 5, versus 0 of 11 patients (0%) reoperated on before day 5 (NS). Univariate analysis showed that three clinical characteristics were associated with a significantly high risk of mortality after reoperation for anastomotic leakage: age greater than 65 years (p < 0.01), American Anesthesiologist Association score greater than 3 (p < 0.05), and blood transfusions during the first operation (p < 0.02). CONCLUSIONS: In our study, some postoperative clinical and biologic signs were associated with a higher risk of anastomotic leakage. The knowledge of these findings might help in the early diagnosis and management of patients with anastomotic leakage after large bowel resection.

Anastomosis, Surgical↗
PubMed1999

Immunological alterations in patients with primary tumors in central nervous system.

Natural killer (NK) cells play an important role in immune surveillance against tumors. The present work aimed to study the cytotoxic activity of NK cells and T cell subsets in peripheral blood of 13 patients with primary tumors in central nervous system (CNS). As controls 29 healthy subjects with the age range equivalent to the patients were studied. The methods employed were: a) determination of cytotoxic activity of NK cells towards K562 target cells, evaluated by single cell-assay; b) enumeration of CD3+ lymphocytes and their CD4+ and CD8+ subsets defined by monoclonal antibodies; c) the identification of tumors were done by histologic and immunochemistry studies. The results indicated that adults and children with tumor in CNS display reduced percentage of total T cells, helper/inducer subset and low helper/suppressor ratio. The cytotoxic activity of NK cells was decreased in patients with CNS tumors due mainly to a decrease in the proportion of target-binding lymphocytes. These results suggest that cytotoxic activity of NK cells may be affected by the immunoregulatory disturbances observed in patients with primary tumors in CNS.

Adolescent↗
PubMed1999

Are apolipoproteins A and B better than lipoproteins for assessing risk of obstructive coronary heart disease?

OBJECTIVE: To evaluate whether apolipoproteins A-I (Apo A-I) and B (Apo B) have, higher ensitivity (SN), specificity (SP) and positive predictive value (PPV) than lipoproteins (LP), total cholesterol (TC), high density lipoprotein (HDL), low density lipoprotein (LDL), very low density lipoprotein (VLDL), and triglycerides (TGL) in assessing the risk of coronary heart disease (CHD). METHODS: This is a transversal case-control study of 241 patients, who were divided into two groups: 1) 145 patients with CHD, and 2) 96 patients without coronary disease. A model of logistic regression to evaluate the relation between the LPs and CHD was developed in which variables with a p-alpha < 0.1 were included. RESULTS: Apo A-I levels were higher in the patients without CHD, (OR 2.08, CI 1.20-3.57). There were no statistical differences between the values of Apo A-I and the remaining lipid fractions (Apo A-I: 67%; Apo B: 100%; PPV: TC = 71%; TGC = 71%; HDL = 71%; LDL = 71%). The costs of the tests in Reais were as follows: Apo A-I: R$ 56.60; Apo B-100: R$ 56.60; TC: R$ 9.94; HDL: R$ 21.30; LDL: R$ 28.40; TGL: R$ 14.20. CONCLUSION: Levels of Apo A-I and Apo B have no advantage over conventional lipoproteins in predicting the risk of CHD, despite the statistical association between Apo A-I and CHD; in addition, their costs are higher than those of the conventional lipoproteins.

Aged↗
PubMed1998

Anatomy of spontaneous splenorenal and gastrorenal venous anastomoses. Review of the literature.

Portal hypertension is characterised by the development of a collateral portocaval circulation. Among these venous reroutings, some are situated posteriorly in the left subphrenic compartment. These are the spontaneous splenorenal and gastrorenal anastomoses. Their incidence is estimated at around 16%. On the one hand, there are the direct shunts, which anastomose the spelling v. to the left renal v., of an anecdotal nature, and on the other the spontaneous indirect splenorenal shunts, characterised by the presence of a complete neurovascular pedicle traversing the gastrophrenic ligament. This relates to the gastric collateral v., which is connected to the left renal v. via the inferior v. of the left crus of the diaphragm and the middle capsular v., hence the name "gastro-phreno-capsulo-renal shunt". At an advanced stage of portal hypertension these splenorenal shunts may acquire a major caliber and behave like actual surgical shunts.

Collateral Circulation↗
PubMed1998

[Nutritional evaluation of children with respiratory failure (RF): anthropometric evaluation upon admission to the pediatric intensive care units].

OBJECTIVE: Protein-energy malnutrition (PEM) constitutes an important complication in children submitted to intensive care treatment for respiratory failure (RF). This complication is not usually evaluated in assessment protocols. Nutrition assessment in a Pediatric Intensive Care Unit (PICU) was performed in children with respiratory failure. PATIENTS AND METHODS: A prospective study involving 65 children (1-158 months of age) with RF at admission to the PICU was carried out. The patients studied were divided into four groups according to their etiology: Group I (n = 29) included those with acute bronchial pathology; Group II (n = 17) those with pneumonia: Group III (n = 11) those in the post-operative period following cardiac surgery; and Group IV (n = 8) those patients with multiple-organ dysfunction. All patients in Groups I, II, and III had chronic diseases. Anthropometrical and nutritional evaluation included weight, height and body mass index (w/h2). RESULTS: The weight for age was low (59%). Height deficit was observed in a significantly lower percentage of the patients (13.1%). The body mass index showed values in relationship to the 50th percentile that varied between 83.4 +/- 23.1% and 97.1 +/- 4.7%. In 68.9% of the patients the criteria of global malnutrition were met according to the classification of McLaren and Read. CONCLUSIONS: The data confirm that PEM is frequent in patients with RF in the PICU and emphasize the usefulness of anthropometrical evaluation as an important, simple and non-invasive method of nutritional evaluation. Early and intensive nutritional intervention can reduce or prevent the vicious circle of malnutrition in RF patients hospitalized in the PICU.

Body Height↗
PubMed1998

[Diagnostic strategy in abdominal injuries].

There is persistent controversy concerning the management of patients with abdominal trauma. The major point is to determine whether or not the abdominal trauma is penetrating. In rare cases (shock, abdominal gunshot wound, peritonitis, evisceration, digestive tract bleeding and abdominal stab out of place) urgent laparotomy remains mandatory. In the other cases, although some centers recommend serial abdominal exams for asymptomatic patients, with the risk of delayed laparotomy, most authors prefer a more aggressive approach. In the case of anterior penetrating abdominal trauma, diagnostic peritoneal lavage, which is an over sensitive method, could be replaced by laparoscopy, which allows both diagnosis and treatment. Triple-contrast CT scan is the first-line diagnostic modality in penetrating back and flank trauma.

Abdominal Injuries↗
PubMed1997

[Possible role of the immune system in lead peripheral polyneuropathy. Case report].

This is a case report of a twenty-five years old man who developed, due to lead intoxication, a severe axonal peripheral predominantly motor neuropathy, after a shotgun injury. The projectile was retained in the right hip. Before this diagnosis had been done he was treated with corticosteroids in immunosuppressive doses and showed an improvement, but he had worsened at each attempt to interrupt the drug. Because he had also other signs of lead intoxication, such as abdominal cramps, severe anemia and seizures it was search for the blood levels of lead that was 101.2 micrograms/dl. The patient was treated with calcium disodium edetate and surgical removal of lead fragments. After that he had a good outcome with no need of corticosteroids. It is emphasized the possible relevance of the immune system on the mechanism of plumbic intoxication and the importance of the withdrawal of the lead material retained in joints.

Adult↗
PubMed1997

[Sarcoma of endometrial stroma (SEE). Clinical and pathological prognostic factors].

Endometrial Stromal Sarcomas are rare neoplasms, accounting for 0.2% of female genital tract malignancies. They occur predominantly in post menopausal women, although they can develop during the reproductive years or even in childhood. The most important prognostic factors are the patient's age at diagnosis, FIGO surgical stage, myometrial invasion, mitotic index, DNA index and tumoral necrosis. In this study we try to evaluate the main prognostic factors in the women treated in the Portuguese Oncology Institute in Oporto. From the study of the 14 patients with the diagnosis of endometrial stromal sarcoma, between 1974 and 1995, we can conclude that the main factors influencing the outcome were FIGO surgical staging, mitotic index and myometrial invasion.

Adolescent↗
PubMed1995

[A peripheral neuroectodermal tumor of the vulva].

A case of malignant peripheral neuroectodermal tumor occurring in the vulva of a 29-year-old woman is reported. It is a rare malignant tumor with aggressive biological behavior belonging to a wide group, the so-called small round-cell tumors. The patient is well and free of disease 8 months after surgery, chemotherapy and radiation therapy.

Adult↗
PubMed1995

[Lafora's disease: a possible diagnosis of juvenile dementia].

Five patients aged 12 to 16 years old were admitted between 1987 and 1994 at the neurological unit because of uncontrolled epilepsy. They had had a normal development until the adolescence, when a history of poor school performance and memory difficulty started. It is emphasized the clinical sequence of dementia followed by tonic-clonic seizures and myoclonus, the positive family history and the difficult therapeutic management, in spite of multiple anticonvulsant combinations, including sodium valproate and clonazepam. The clinical and laboratory differential diagnosis were discussed to show that similar cases should be submitted to skin biopsy looking for Lafora bodies in apocrine and eccrine glands. However, the liver is considered as the most reliable site for the biopsy, which in our study showed positivity in four out of the five cases.

Adolescent↗
PubMed1992

[Cystic oligodendroglioma and positivity of reactions for cysticercosis: report of a case].

A case of a 32-year old male patient with complaints of frontal headache progressive decrease in visual acuity, altered behaviour, and positive results of immunological tests for cysticercosis performed on the cystic and cerebrospinal fluids is presented. After several clinical and surgical proceedings, the frontal craniotomy was indicated and a multi-lobulated cystic tumor was excised. Biopsy material revealed an oligodendroglioma invading the degenerated membrane of cystic wall. Some aspects related to the possible mechanisms involved in the association of oligodendroglioma with neurocysticercosis in the presented case are discussed. Three different types of conclusions may be reached: (1) neurocysticercosis may have acted as an oncogenetic factor for the oligodendroglioma; (2) the glycoprotein nature of the antigens of gliomas and cysticercosis and the similarity in the molecular weight range of their polypeptides may be responsible for the positivity of the reactions for cysticercosis in the cystic fluid; or (3) the association of oligodendroglioma with cysticercosis may be a simple coincidence. The present study strengthens the opinion that other pathologies should be looked for when clinical treatment of cysticercosis does not follow the expected course.

Adult↗