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Biomedical subjects

J Ribeiro

Publications and source records attributed to J Ribeiro.

At least 19 recordsLinked to original sources
PubMed2006

Hemostatic response to acute physical exercise in healthy adolescents.

The chronic and immediate post-exercise responses in the hemostatic and fibrinolytic systems have been shown to be variable and reflect differing adaptations with ageing and responses to exercise protocols. This study investigated the effects of acute and exhaustive exercise on the amplitude and duration of hemostatic and fibrinolytic responses in young adolescent males. The sample comprised 10 sedentary boys (13.2+/-0.5 years, 55.8+/-11.3kg, 165.7+/-7.4cm), who had not exercised or received any medication for at least 2 weeks before the experiments. The subjects performed exhaustive stepping exercise, consisting of 1s up and down cycles to fatigue. When the subjects were unable to maintain the required stepping rhythm, they were given a 30s recovery period. Following each 30s recovery participants recommenced the stepping cadence until fatigue prevented them continuing. Venous blood samples were drawn before and immediately, 1 and 24h after exercise to assess the following coagulation and fibrinolytic parameters: Platelet counts, activated partial thromboplastin time (aPTT), prothrombin time (PT), coagulation factor VIII (FVIII:C), von Willebrand factor (vWF), fibrinogen concentration, thrombin-antithrombin complex (TAT), D-dimer, plasminogen activator inhibitor (PAI-1), and tissue-type plasminogen activator (t-PA). Immediately following exercise, platelet counts, aPTT, FVIII, vWF and t-PA were significantly elevated in contrast to PAI-1, which decreased significantly until 1h after exercise. FVIII and platelet counts were elevated at 1 and 24h after exercise, respectively. Only the parameters FVIII and PAI-1 did not return to baseline values during the first hour after physical exercise. When compared to adults the results revealed different rates and ranges of coagulation and fibrinolysis parameters being activated by exhaustive exercise in this group of adolescents.

Adolescent↗
PubMed2006

Exhaustive exercise with high eccentric components induces prothrombotic and hypofibrinolytic responses in boys.

It is known that coagulation and fibrinolysis are activated after exercise, and that the response is related to exercise intensity. The contribution, however, of eccentric exercise has not yet been investigated. Twenty boys (age 13 years) were randomly assigned to two experimental groups, which had to perform a monopedal stepping exercise until exhaustion. One group had to step up and down (U/D) in the same rhythm of one second each, while the other group (U/DD) had to step up during one second and to step down during two seconds, thereby experiencing a higher eccentric load. Blood samples were collected before and at 0, 1, and 24 hrs after exercise, and F VIII, t-PA, PAI-1, and D-dimer were determined as markers for coagulation or fibrinolysis, respectively. While the tendency for hypercoagulability was counterbalanced by fibrinolysis in the U/D group, the U/DD group showed a prothrombotic and hypofibrinolytic hemostatic response. It is assumed that eccentric exercise, beyond the well-known muscle fiber damage, also leads to some damage of the endothelial cells, affecting their capacity to liberate sufficient amounts of fibrinolytic agents.

Adolescent↗
PubMed2006

Effect of medium sugar source on the production of retroviral vectors for gene therapy.

The production of gene therapy retroviral vectors presents many difficulties, mainly due to vector instability and low cell productivities hampering the attainment of high titers of infectious viral vectors. The objective of this work is to increase the production titers of retroviral vectors by manipulating the sugar carbon sources used in bioreaction. Four sugars were tested (glucose, galactose, sorbitol, and fructose) on an established Moloney murine leukemia virus (MoMLV) producer cell line. Galactose and sorbitol did not support cell growth or vector production. Glucose supplemented at 25 mM supported the highest cell growth; however, the use of glucose or fructose at 83 and 140 mM have shown to improve the infectious vector titer three to fourfold. The reasons for the titer improvements were further analyzed and, although, the cell-specific productivity in viral transgene RNA and reverse transcriptase were augmented 5- and 6-fold for glucose at 140 mM and 14- and 16-fold for fructose at 140 mM, comparing with glucose at 25 mM, these increases did not seem sufficient to account for the 14- (140 mM glucose) and 32- (140 mM fructose) fold increment obtained for the infectious particles-specific productivity. Further accounting the enhancement in the titers was the improvement in the viral stability, the half-life of the vectors was enhanced by 30-60%. This resulted in a product quality with a superior ratio of infectious to total particles, thus reducing the most problematic contaminant in the production of retroviral vectors, non-infectious retroviral particles.

Carbohydrates↗
PubMed2006

Microbiological and epidemiological characterization of imipenem-resistant Pseudomonas aeruginosa strains from a Brazilian tertiary hospital: report from the SENTRY Antimicrobial Surveillance Program.

OBJECTIVES: To evaluate the antimicrobial susceptibility profile, the genetic similarity, and the mechanisms of carbapenem resistance among imipenem-resistant Pseudomonas aeruginosa isolates collected from a Brazilian tertiary teaching hospital. METHODS: Seventy-eight consecutive samples of P. aeruginosa were evaluated during 2000 and 2001. The antimicrobial susceptibility was evaluated by reference broth microdilution methods and the imipenem-resistant isolates were screened for metallo-beta-lactamase (MbetaL) production throughout disc approximation test and MbetaL Etest strips and isolates with positive screen test result were submitted to PCR assays using primers blaIMP-1, bla VIM-1, blaVIM-2 e blaSPM-1. The genetic similarity of MbetaL-producing strains was evaluated by automated ribotyping for epidemiological typing purpose. RESULTS: Resistance rates were high to the majority of antimicrobial agents tested except polymyxin B, which inhibited all samples at the Clinical and Laboratory Standards Institute breakpoint (< or = 2 microg/ml). Twenty-nine (37.2%) isolates were resistant to imipenem and these isolates showed great genomic variability. MbetaL production was demonstrated in two imipenem-resistant isolates, which were detected using blaSPM-1 and blaIMP-2-specific primers. Sequence analysis revealed the presence of blaSPM-1 and a novel blaIMP-type gene, blaIMP-16. CONCLUSION: The results of this study showed high resistance rates to the majority of antimicrobial agents among P. aeruginosa samples. High imipenem resistance rates were probably due to continuous selection of resistant mutants. The production of MbetaL did not represent a frequent mechanism of carbapenem resistance in this medical center; but a novel MbetaL was identified. Continued antimicrobial surveillance and infection control measures should be emphasized to minimize the emergence and dissemination of antimicrobial resistance.

Adolescent↗
PubMed2002

Cytometric, morphologic and enzymatic characterisation of haemocytes in Anodonta cygnea.

The haemocytes in bivalve mussels are involved in many processes such as lesion repair, shell repair, elimination of small particles and toxic substances. In Anodonta cygnea there are two categories of haemolymph cells, the granulocytes and hyalinocytes. Two groups of cells were identified by flow cytometry and morphological studies: one with larger size and granularity representing 75%, and another group of cells (25%) which were approximately half the size. The cytochemical reactions showed peroxidase activity in the larger cells and a weak prophenoloxidase activity in the smaller cells. These characteristics suggest that the most common haemocytes are granulocytes and hyalinocytes are less common. Enzymatic studies showed clear activities of few enzymes in different compartments of the mantle. Both haemocytes presented significant variations for alpha-manosidase and beta-glucurosidase activities depending on the acid or alkaline pH. Almost all were sensitive to the pH changes, mainly the beta-galactosidase in the haemolymph plasma. On the contrary, the same enzymatic analysis in the extrapallial elements showed more stabilised activities. The simulation of acidic and alkaline condition with the observation of significant morphological and enzymatic activity changes, allow us to speculate some functional role, mainly in the haemolymph elements. The granulocytes may be speculated to have intense involvement in the digestion of small residues with the formation of calcareous stores while the hyalinocytes are more responsible for the elimination of soluble cytotoxic compounds.

Animals↗
PubMed2001

Influence of the interval between the administration of doxorubicin and paclitaxel on the pharmacokinetics of these drugs in patients with locally advanced breast cancer.

PURPOSE: The combination of bolus doxorubicin followed by a 3-h infusion of paclitaxel has high antitumor activity in patients with metastatic breast cancer, but is limited by unexpected cardiac toxicity. In contrast, the administration of the two drugs 16 h apart has similar antitumor activity but less cardiac toxicity. The purpose of this study was to compare the pharmacokinetics of these drugs when doxorubicin administration preceded paclitaxel by 30 min or by 24 h. PATIENTS AND METHODS: Women with locally advanced breast cancer were treated with doxorubicin (60 mg/m2 i.v. bolus) followed 24 h later by paclitaxel (200 mg/m2 i.v. over 3 h) for six cycles (four before and two after surgery). In one of the first two cycles doxorubicin preceded paclitaxel by 30 min instead of 24 h, with plasma sampling for pharmacokinetic analysis up to 48 h. Determination of drug levels in plasma was done by HPLC. RESULTS: A total of 28 patients were included. No clinical cardiac toxicity was observed but five patients discontinued doxorubicin-paclitaxel treatment after four cycles because of a decrease in LVEF of at least 15% from baseline or to less than 50%. While paclitaxel pharmacokinetics were not changed, there was a 30% and an 80% increase in the AUC0, 24h for doxorubicin and doxorubicinol, respectively, when the drugs were administered 30 min instead of 24 h apart. Even when paclitaxel was given 24 h after doxorubicin, there was a rebound 240% increase in the plasma concentration of doxorubicinol. CONCLUSIONS: Paclitaxel interferes with the pharmacokinetics of doxorubicin leading to higher systemic exposure to both doxorubicin and doxorubicinol, which is more evident when the plasma concentration of the anthracyclines is higher. This interference may explain the higher incidence of cardiac toxicity observed when the two drugs are administered within a short interval.

Adult↗
PubMed2000

Imaging findings in pediatric adrenocortical carcinoma.

BACKGROUND: Adrenocortical carcinoma (ACC), a tumor that is rare among children, causes clinically evident hormonal disturbances. Imaging methods are used to stage disease and to plan surgical resection. OBJECTIVE: To describe the findings of the various imaging methods used to evaluate ACC. MATERIALS AND METHODS: We reviewed the records of ten consecutive patients (mean age, 8.1 years) who presented from 1987 to 1998 with ACC. All patients underwent computed tomography (CT) scanning; five underwent magnetic resonance (MR) imaging; four underwent ultrasonography (US); and eight underwent radionuclide bone scans. RESULTS: Seven patients presented with signs of hormonally functional tumors. Typical imaging findings consisted of a large, well-defined suprarenal tumor, containing calcifications (seven patients) with a thin capsule and central necrosis or hemorrhage (six patients). The inferior vena cava (IVC) was compressed by tumor in three patients, and ultrasonography demonstrated invasion of the IVC wall in one of these. Three patients' bone scans showed that the primary tumor took up radioactive tracer. Spread to lungs or liver or both was demonstrated in six patients. CONCLUSIONS: CT, US and MR imaging are effective methods of imaging the primary tumor. Chest CT and bone scintigraphy should be performed to detect metastases. The presence of a thin tumor capsule, a stellate central zone of necrosis, and evidence of hormonal function help distinguish ACC from neuroblastoma.

Adolescent↗
PubMed1999

Misclassification of susceptible strains of Staphylococcus aureus as methicillin-resistant S. aureus By a rapid automated susceptibility testing system.

Eight Staphylococcus aureus strains initially identified by Vitek GPS-BS or GPS-SA cards as resistant to oxacillin, but susceptible to most non-beta-lactam antibiotics, were found on further testing to be susceptible to oxacillin and ceftizoxime by disk diffusion tests. For all these strains, the MICs of oxacillin were </=0.5 microg/ml by agar dilution tests, and the strains were oxacillin susceptible when tested by the BBL Crystal MRSA ID and a Vitek machine with GPS-101 cards. None grew on oxacillin-salt agar screening plates. None were positive for mecA gene sequences by PCR. When S. aureus strains tested by Vitek GPS-SA or GPS-BS cards appear resistant to only penicillin and oxacillin, a confirmatory test such as the oxacillin-salt agar screening method should be performed.

Methicillin Resistance↗
PubMed1998

Development of a natural model of cutaneous leishmaniasis: powerful effects of vector saliva and saliva preexposure on the long-term outcome of Leishmania major infection in the mouse ear dermis.

We have developed a model of cutaneous leishmaniasis due to Leishmania major that seeks to mimic the natural conditions of infection. 1,000 metacyclic promastigotes were coinoculated with a salivary gland sonicate (SGS) obtained from a natural vector, Phlebotomus papatasii, into the ear dermis of naive mice or of mice preexposed to SGS. The studies reveal a dramatic exacerbating effect of SGS on lesion development in the dermal site, and a complete abrogation of this effect in mice preexposed to salivary components. In both BALB/c and C57Bl/6 (B/6) mice, the dermal lesions appeared earlier, were more destructive, and contained greater numbers of parasites after infection in the presence of SGS. Furthermore, coinoculation of SGS converted B/6 mice into a nonhealing phenotype. No effect of SGS was seen in either IL-4- deficient or in SCID mice. Disease exacerbation in both BALB/c and B/6 mice was associated with an early (6 h) increase in the frequency of epidermal cells producing type 2 cytokines. SGS did not elicit type 2 cytokines in the epidermis of mice previously injected with SGS. These mice made antisaliva antibodies that were able to neutralize the ability of SGS to enhance infection and to elicit IL-4 and IL-5 responses in the epidermis. These results are the first to suggest that for individuals at risk of vector-borne infections, history of exposure to vector saliva might influence the outcome of exposure to transmitted parasites.

Animals↗
PubMed1998

[Analysis of the reactive capacity of intracerebral circulation with CO2. A method easily performed].

Maintenance of cerebral perfusion pressure is a prerequisite for the prevention of cerebral ischaemia. Physiological fluctuations in systemic perfusion pressure are compensated by cerebrovascular autoregulation. Cerebral perfusion reserve may be determined by assessing changes in cerebral blood flow using vasodilating stimuli. Transcranial Doppler has been used to assess cerebral blood flow speed in response to those stimuli. We describe a method using Transcranial Doppler with CO2 to analyse cerebral vasoreactivity. The method can be useful to determine hemodynamic reserve in different cerebral ischaemic diseases.

Adult↗
PubMed1998

[Left ventricular filling in young patients with systemic lupus erythematosus in stable phase].

OBJECTIVE: The aim of this study was to evaluate the left ventricle filling pattern in patients with stable systemic lupus erythematosus (SLE). METHODS: This prospective study was performed in 22 healthy controls and in 24 patients with stable SLE. These two groups were submitted to a clinical, electrocardiographic and echocardiographic evaluation. RESULTS: Gender distribution and mean age were similar in both groups (p = NS). Patients with SLE were more symptomatic (21%) than control patients (0%) (p < 0.01). Left ventricular dimensions, wall thickness, and systolic function were not significantly different between the two groups. However, pericardial effusion was more frequently found in patients with SLE (21%) when compared to the control group (0%) (p < 0.05). When compared to the control group, patients with SLE showed an abnormal left ventricular filling pattern. Peak late mitral flow velocity was 0.45 +/- 0.2 m/sec in SLE patients and 0.36 +/- 0.1 m/sec in the control group (p = 0.001). CONCLUSION: These results demonstrate that patients with stable SLE, when compared to healthy controls, are frequently associated with cardiovascular symptoms, asymptomatic pericardial effusion, and an abnormal left ventricular filling pattern.

Adult↗
PubMed1997

[Acute myocardial infarct--the hospital phase and follow-up: sex-related differences].

OBJECTIVES: The aim of this study was to evaluate the differences between male and female patients, during hospitalization and follow-up, after acute myocardial infarction. PATIENTS: The clinical data and follow-up files of 504 previously hospitalized patients were studied. The patients were divided in two groups: Group A (male, n = 434) with a mean age of 56.4 +/- 11.7 years, and Group B (female, n = 70) with a mean age of 64.1 +/- 9.2 years. METHODS: The following parameters were studied: vascular risk factors; clinical, functional and anatomic aspects during hospitalization; therapeutic orientation and events; and mortality during follow-up. RESULTS: Hypertension, diabetes, obesity, anterior infarction and lower ejection fraction were more common in Group B. Coronary angiography and thrombolytic therapy were performed more frequently in Group A; severe coronary disease was more common in this group (60.8% vs 38.9%, p < 0.05). During the follow-up we observed a worse prognosis in the Group B, with a higher incidence of events, morbidity and mortality. Therapeutic approach was more aggressive in the male group. CONCLUSION: We observed a worse prognosis in the female patients after myocardial infarction, this fact may be attributed to a later age and higher previous morbidity; the therapeutic and diagnostic procedures are generally less aggressive in females, who are consequently referred for revascularization with more advanced stages of disease, and therefore with higher morbidity and mortality, in the short and long term, even though multivessel coronary disease is more common in males. Thrombolytic therapy was administered and coronary angiography was performed more often in Group A, who had more severe coronary disease.

Aged↗
PubMed1997

[The effects of a cardiac rehabilitation program on 2 populations of coronary patients: acute myocardial infarct and coronary bypass surgery].

UNLABELLED: Cardiac rehabilitation programmes (CRP) have proven beneficial in coronary heart disease. The purpose of this study was to evaluate the effects of our CRP on two coronary heart disease populations: after acute myocardial infarction (AMI-CRP) and after coronary artery bypass surgery (CABG-CRP). Results were compared to control groups (AMI-C and CABG-C). POPULATION: Group AMI-CRP: n = 43 patients, mean age = 48.7 +/- 9.8 years; Group AMI-C: n = 20 patients, mean age = 59.2 +/- 11.5 years; Group CABG-CRP: n = 54 patients, mean age = 54.9 +/- 9.7 years; Group CABG-C: n = 20 patients, mean age = 56.5 +/- 9.9 years. All patients are male and there were no significant differences in ventricular function and coronary disease severity. Parameters were evaluated in the AMI groups at discharge, 3 and 12 months after acute episode; in the CABG groups 3 and 12 months after surgery. RESULTS: Both CRP groups improved their exercise capacity (significantly improved the peak values of METs and double product). A favorable lipid profile change (total cholesterol and HDL) was induced in the CABG-CRP group and more significant in the AMI-CRP group. No significant differences were observed in obesity indexes (body weight and BMI > or = 27.8 Kg/m2). A increase in nonsmokers was important in all groups. Professional reintegration was 91.7% in the AMI-CRP group and 84.4% in the CABG-CRP group. The CRP groups showed a better knowledge of the disease, and a beneficial change in relation to themselves and the world that resulted in a decrease in depression and anxiety. CONCLUSIONS: Participation in our cardiac rehabilitation program, either after AMI or after CABG, improves cardio-respiratory fitness, favorably influences blood lipid profiles, and improves self-reliance and quality of life.

Adult↗
PubMed1996

Glutamine metabolism and neuropathological disorders in experimental hepatic encephalopathy: effect of transplanted hepatocytes.

BACKGROUND: Physiopathology of hepatic encephalopathy remains unclear. Recent studies have suggested that ammonia would not act by itself but through an increase in glutamine in the brain. We have previously demonstrated that transplantation of syngeneic hepatocytes into the spleen was able to correct both behavioral deficits and plasma amino acid changes observed in portacaval shunted rats. The aim of the present work was to show a correlation between the correction of chronic hepatic encephalopathy by means of intrasplenic hepatocyte transplantation and two parameters, brain glutamine concentration and ultrastructural aspects of astrocytes. METHODS: Inbred male Wistar Furth rats were divided into three groups: sham-operated rats (n = 10), rats subjected to portacaval shunt (n = 10), and rats subjected to portacaval shunt and intrasplenic hepatocellular transplantation of 10(7) hepatocytes isolated from livers of syngeneic rats (n = 10). Chronic hepatic encephalopathy was quantified 30 and 60 days after operation by means of nose-poke exploration and spontaneous activity. Pathologic examination and measurement of glutamine concentrations in the corpus striatus and in the cerebral cortex were performed 60 days after operation. RESULTS: Portacaval shunt rats showed reduced spontaneous activity and nose-poke exploration scores. After portacaval shunt a significant glutamine increase occurred in the corpus striatus and in the cerebral cortex when compared with sham rats (p < 0.05). Ultrastructural examination showed modification of astrocytes named Alzheimer type II after portacaval shunt. Correction of behavioral abnormalities by means of intrasplenic hepatocyte transplantation was associated with partial correction of striatal glutamine increase and with decrease in astrocyte alterations. Cortex glutamine concentration in portacaval shunt-intrasplenic hepatocyte transplantation group and in portacaval shunt rats did not differ significantly. CONCLUSIONS: These data show that intrasplenic hepatocyte transplantation not only prevents neurologic disorders of hepatic encephalopathy but can also decrease glutamine and ultrastructural alterations in the corpus striatus in an experimental model of chronic liver failure. These data are in favor of the involvement of glutamine in chronic hepatic encephalopathy. These results suggest that intrasplenic hepatocyte transplantation might be of therapeutic interest in chronic liver failure.

Animals↗