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Biomedical subjects

A Brito

Publications and source records attributed to A Brito.

At least 19 recordsLinked to original sources
PubMed2001

Parental self-efficacy and morbidity in pediatric asthma.

This study investigated the relationship between parental self-efficacy and asthma-related morbidity. Participants included 139 parents of children (ages 5-8) who were diagnosed with asthma and were primarily from lower-income and minority backgrounds. Parents completed a 22-item measure of self-efficacy; factor analysis was conducted on this measure, yielding two factors: learned helplessness and self-efficacy. Correlational analyses indicated that higher scores on the learned helplessness factor were significantly related to increased asthma-related morbidity for the majority of morbidity variables. The self-efficacy factor was significantly related to days of school missed. Regression analyses conducted with the factor scores and the morbidity variables provide further support that the learned helplessness factor accounts for a significant amount of the variance in asthma morbidity for many of the variables studied, while the self-efficacy factor was related to only a few. Although improving health outcomes of children with asthma is a multifaceted process, the results of this study suggest that targeting parental self-efficacy, particularly with parents who are experiencing high levels of perceived learned helplessness, may be a helpful component of an intervention program with this population.

Asthma↗
PubMed2000

School-based identification of asthma in a low-income population.

The increase in the prevalence, morbidity, and mortality of asthma among children over the last decade has been well documented, especially among low-income minority children. Hypotheses for the increases in morbidity and mortality include limited access to primary care services and the failure to recognize the presence and severity of asthma. The University of Miami Pediatric Mobile Clinic (Mobile Clinic) Asthma Intervention Program is designed to identify underserved asthmatic children at school and offer them culturally sensitive care. Nine elementary schools with low income, predominantly Hispanic and African-American populations regularly served by the Mobile Clinic, were chosen for study participation. All 5,800 students who were enrolled in kindergarten through third grade were given letters at the time of registration by their homeroom teachers about the asthma program. Caretakers who returned the questionnaire and reported that the student had asthma symptoms were invited to have the student undergo a medical evaluation in the Mobile Clinic. Over a 2-year period, caretakers of 423 students (7.3% of all students) expressed an interest in further evaluating their child's respiratory health. Of these, we enrolled and evaluated 154 in the Mobile Clinic's Asthma Intervention Program. The Mobile Clinic physicians identified 145 of the enrollees as having asthma. These results indicate that in elementary schools serving predominantly low-income minority populations, a large fraction of the asthmatic population (estimated prevalence, 6-10%) can be identified by a school-based letter. Further, in a subset of asthmatic students (children of interested caretakers), there is good agreement between caretaker responses and physician diagnosis of asthma. Since school attendance is mandatory, school-based methods may be an effective method for identifying low-income children with asthma.

Black or African American↗
PubMed2000

Monoclonal antibodies against hepatitis B s antigen: production, characterization, and use for diagnosis.

Three different hybridoma clones secreting anti-HBsAg antibody were constructed by fusing cells of mouse myeloma line Ag8-X63 with splenocytes from BALB/c mice immunized with recombinant HBsAg and natural HBV. The monoclonal antibodies obtained were characterized immunologically, and two were used to develop UMELISA for detection of HBsAg. This monoclonal assay enabled the detection of 0.1 UPE/mL with reference to the standard of the Paul Ehrlich Institute (Frankfurt, Germany). The assay compared well with a commercially available kit (UMELISA HBsAg) and was used for detection of HBsAg in blood donors.

Animals↗
PubMed2000

Disruption of the intestinal barrier and bacterial translocation in an experimental model of intestinal obstruction.

Clinical evidence and the use of experimental models in laboratory animals indicate that the intestine is a reservoir of microorganisms that can cause systemic infection in the human. The purpose of this work was to study the possible effect of intestinal obstruction (IO) on the mechanical and chemical barriers that bring protection against microorganisms crossing from the intestinal lumen towards the systemic tissues. We demonstrated that 24 hours after IO, histological and ultrastructural alterations do occur, seriously compromising the structure of the intestinal barrier in 100% of the studied animals. Likewise, it was observed that during the same period, microorganisms translocation from intestine to the peritoneal cavity and liver (100 and 80% respectively) occurred. The lungs were spared. Changes observed in the intestinal epithelium are related to a process similar to that produced by intestinal ischemia: mitochondrial destruction, with subsequent decrease of its capacity to supply energy and to preserve the equilibrium and structure of the intestinal epithelium. We propose that translocation of enteric bacteria may be the cause of the infection that brings about the death a significant group of animals at 48 hours (27%) and 72 hours (33%) post-IO.

Animals↗
PubMed1998

Relevance of serum bile acid profile in the diagnosis of intrahepatic cholestasis of pregnancy in an high incidence area: Portugal.

OBJECTIVE(S): The present work was conducted to clarify the relevance of usual liver function tests, and define the most predictive serum bile acid profile for diagnosis of intrahepatic cholestasis of pregnancy (ICP). STUDY DESIGN: This study comprised 20 healthy nonpregnant women and 77 pregnant women in the last trimester of pregnancy, from which 38 were normal pregnancies, and 39 suffered from ICP. Liver function tests were evaluated by routine laboratory techniques, conjugated bile acids were analysed by high-performance liquid chromatography, and unconjugated forms were measured by an enzymatic-fluorimetric assay. RESULTS: During the third trimester in normal pregnancy, increased concentration of conjugated species affected all primary bile acids, although only significantly for glycocholic acid. Moreover, deoxycholic acid proportion decreased when compared with healthy nonpregnant women. Important ICP-induced changes in serum profiles of amidated bile acids were observed, involving both a marked increase in cholic acid concentration and a shift towards a higher proportion of taurine-conjugated species. Among routine liver tests, alanine aminotransferase and conjugated bilirubin were the most common indicators of ICP. CONCLUSION(S): In the early diagnosis and follow-up of ICP, the most predictive and accurate markers (efficiency 100%) were: (i) TBA concentration in serum >11.0 micromol(-1): (ii) cholic/chenodeoxycholic acid ratio >1.5 and cholic acid percentage >42%: (iii) glycine/taurine bile acid ratio <1.0 or glycocholic acid concentration >2.0 micromol(-1). Accurate diagnosis based on sensitive biochemical markers followed by appropriate treatment may improve both pregnancy outcome and newborn prognosis.

Adolescent↗
PubMed1997

Effect of bilirubin on erythrocyte shape and haemolysis, under hypotonic, aggregating or non-aggregating conditions, and correlation with cell age.

The effect of unconjugated bilirubin on the morphology and haemolysis of human erythrocytes was accomplished under distinct incubation conditions: (i) hypotonic medium, with bilirubin concentrations ranging from 1 x 10(-9) to 1 x 10(-4) mol l-1; (ii) isotonic medium, with 171 mumol l-1 bilirubin, in the absence of albumin (aggregating conditions), using non-separated and age-fractionated erythrocytes; (iii) isotonic medium, with 171 mumol l-1 bilirubin, in the presence of a surplus of human serum albumin (non-aggregating conditions), and using sulfisoxazole as a bilirubin displacer (bilirubin/albumin and sulfisoxazole/ albumin molar ratios of 0.5 and 4.0, respectively). Our data showed that low concentrations of bilirubin (1 x 10(-7) to 1 x 10(-5) mol l-1) protect against hypotonic haemolysis and induce crenation, while higher bilirubin concentrations induce haemolysis and lead to membrane disruption. When aggregating conditions were used, these phenomena were reproduced, the younger cells being significantly more susceptible to crenation while the older erythrocytes showed increased susceptibility to haemolysis. In non-aggregating conditions, haemolysis was virtually absent, though crenation was evident. Based on the above observations we conclude that the first step of erythrocyte bilirubin toxicity is crenation due to an expansion of the outer membrane leaflet by bilirubin mono-anion location. This effect is more evident in younger cells and explains the protection against the hypotonic haemolysis. Insertion of bilirubin deeper into the bilayer, facilitated by higher concentrations (> or = 1 x 10(-4) mol l-1) and cell age, produces an unstable situation, where bilirubin acid aggregation is apparently the main cause for haemolysis and cell destruction.

Bilirubin↗
PubMed1994

[Sjögren's syndrome].

This paper consists the theorical review and the current concepts of the subject and the second includes the casuistry of the Stomatology Department of the Pulido Valente Hospital. From April 1989 to 1991 (2 years), a study was made on Sjögren Syndrome (Primary and Secondary) of multiple character with the particular co-operation of the Portuguese Institute of Rheumatology. With this paper we wish to point out the importance of the oral evaluation of the study of the plurisystemic diseases as well as to establish criterions of diagnosis for the Portuguese population. Eighty cases of suspected Sjögren's Syndrome have been assessed, 66 of which have been fully. The reason for the consultation was dry mouth, dry eyes and enlargement of parotid glands. The symptoms were isolated or in association with other pathologies after other causes had been excluded. We had to establish the salivary reference values for the Portuguese population in 22 healthy volunteers. The xerostomia was evaluated by the Sialochemistry, Sialography, Cintigraphy and biopsies of the lower lip and of the sublingual gland. The ophthalmologic examination took place in the Ophthalmology Department of Santo António dos Capuchos Hospital by means of Shirmer test, Rosa Bengala and B.U.T. In spite of Sjögren's Syndrome being, up to now, so remotely determined in connection with the treatment, these patients need medical care and Stomatology plays a fundamental role as far as the diagnosis and the therapeutic points of view are concerned. We maintain the notion that the Syndrome is not as infrequent as one would believe and the evaluation of the oral field is important to establish the degree of the disease and its treatment.

Female↗
PubMed1993

[Protein and energy requirements in patients with severe head injury].

The aim of the present study was to assess the effect of severe head injury over resting energy expenditure and nitrogen losses. Eight patients with severe head trauma (mean Glasgow scale of 4.9 +/- 1.6), subjected to emergency craniotomy were studied; four patients had septic complications and none received steroids. Energy expenditure was measured using indirect calorimetry and nitrogen losses were assessed measuring 24 h urea nitrogen excretion on days 1, 4, 7 and 10 of the postoperative period. Twelve healthy males composed the control group. Measured energy expenditure in patients, evaluated in 22 occasions, was 35 +/- 9.8 Kcal/kg/day or 145 +/- 41% of the estimation according to Harris-Benedict equations, compared to 22.0 +/- 4.6 Kcal/kg/day or 89.9 +/- 17.5% in the control group (p < 0.001). 24 h urinary urea nitrogen excretion in patients was 18 +/- 12 g/day (range 5.2-46.9) and the catabolic index was 7.4 +/- 13.5. It is concluded that, due to the great individual variability in measured energy expenditure in these patients and their hypercatabolism, indirect calorimetry and nitrogen balance studies become useful tools to perform an adequate nutritional support.

Adolescent↗
PubMed1992

MR relaxometry imaging. Work in progress.

Acquisition of relaxation rate dispersion curves from magnetic resonance images was demonstrated on a clinical, whole-body imaging system. Study of the behavior of relaxation rates over a range of field strengths probes the structural environment of imaged hydrogen protons and reveals information about the composition of tissue. The authors determined relaxation rates in extremities and heads of healthy volunteers. The sensitivity of the measurement is sufficient to obtain a distinctive relaxation rate dispersion behavior for different tissues.

Adult↗
PubMed1987

A preliminary study of MRI quantification of simulated calcified pulmonary nodules.

The potential of magnetic resonance imaging (MRI) quantification of calcium for the evaluation of pulmonary nodules was investigated in simulated nodules. Calcium salts do not contain mobile protons and thus have no signal on MR proton images. To determine whether the absence of signal from partially calcified nodules could be quantified, we studied simulated nodules containing known quantities of calcium salts. The soft tissue equivalent material was an agar-gelatin mixture (T1:1100-1500 msec; T2: 59-62 msec). In the first experiments, glass tubes were filled with the mixture, which contained suspensions of calcium carbonate (CaCO3) or silica dioxide (Si02), and were subjected to computed tomography (CT) scanning and MR imaging. In a second series of studies CaCO3 particles of various sizes (and therefore different surface-to-volume ratios) were similarly suspended and subjected to CT scanning and MR imaging. In a third series hydroxyapatite (HA) suspensions of different sizes were similarly studied. CaCO3 produced a significant reduction in MR hydrogen density and signal intensity of the agar-gelatin mixture. Reduction in T1 and T2 relaxation times was inconsistent and not related to particle size. CaCO3 produced its effect by soft-tissue displacement. HA (and Si02) caused a more marked fall in MR hydrogen density, signal intensity, and T1 and T2 relaxation times. The degree of the T1 and T2 effects was related to particle size, indicating a hydrophilic surface effect. The authors conclude that MRI quantification of calcium within pulmonary nodules (or other tissues) will be complex and will relate to the precise composition of the calcium salt and to the particle size of the aggregates.

Calcinosis↗
PubMed1984

Experimental pulmonary emboli detected using magnetic resonance.

Experimental pulmonary emboli that were labelled with non-magnetic barium threads and produced using aminocaproic acid were introduced into the internal jugular veins of five dogs. Transverse axial magnetic resonance (MR) images (0.35 T, 15 MHz) and CT scans (2.0 or 4.8 seconds, G.E. 9800 or 8800 scanner) were obtained from the lung apex to base in each animal. The MR images were gated to the cardiac cycle, and spin echo techniques were used (TR = gated to the cardiac cycle; TE = 28 and 56 msec). Nineteen sites of embolism were determined from the CT scans. Two observers, who had no knowledge of the number or position of the emboli, individually assessed the MR images and marked the sites of emboli on clear acetate overlays. Each observer detected 12 of 19 emboli (63%) and each had one false positive result. Of the 19 emboli, six were central or parahilar and 13 were in the outer two thirds of the lungs. Three (first observer) or four (second observer) of the seven false negative results were central. In retrospect, two central emboli were mistaken for hilar fat. One peripheral embolus was not visible, even in retrospect. The potential for MR to demonstrate relatively small pulmonary emboli has been shown. Clinical trials in patients seem warranted.

Animals↗
PubMed1984

Hepatic cirrhosis: magnetic resonance imaging.

The effect of periportal collagen deposition on magnetic resonance images and T1 and T2 relaxation times was studied in the rat. Hepatic cirrhosis was induced in 29 rats by chronic intraperitoneal thioacetamide injections. Another 14 rats in which liver abnormalities did not develop were used as controls. The rats were imaged using a small-bore resistive magnet. Histologic correlations and hydroxyproline measurements were performed to document the changes in periportal collagen deposition. The T1 and T2 relaxation times, determined both in vivo and in vitro with spectroscopy, were compared between the normal group and the group with moderate to severe histologic evidence of cirrhosis. The deposition of two to four times the normal amount of collagen in the liver did not affect the T1 or T2 relaxation time. Relatively pure periportal collagen fibrosis does not appear to affect the magnetic resonance image or T1 or T2 relaxation times of the rat liver.

Animals↗
PubMed1983

Nuclear magnetic resonance imaging of experimentally induced liver disease.

Experimental animal models of hepatitis, fatty liver, and hepatic iron overload were evaluated using a 3.5-kGauss nuclear magnetic resonance (NMR) imaging system. Increases in image intensity measurements and in T2 relaxation times equalled the sensitivity of histologic findings for the detection of early stages of hepatitis. A significant shift in T1 relaxation times characterized the early stages of hepatic necrosis. Liver triglyceride content correlated significantly with increases in NMR intensity measurements (p less than 0.01); however, changes in liver water content had a much greater influence on intensity, T1, and T2. Thus, it may be possible to distinguish hepatitis from benign fatty liver. Liver iron content correlated with decreases in NMR intensity measurements (p less than 0.001), and iron levels as low as 1.2 mg/g were detected. NMR may more specifically identify hepatocellular iron overload than do other techniques that do not distinguish hepatocellular from reticuloendothelial iron.

Animals↗
PubMed1981

Prader-Willi Syndrome after age 15 years.

Twenty-four patients, all of them over 15 years, with the Prader-Willi syndrome are described. Obesity, often extreme, associated with an insatiable appetite, was their principal handicap and this was made worse by educational subnormality and hypogonadism. Three of the them developed diabetes. Each attended a special school or an adult training centre. Although most of them were of short stature and had scoliosis, 2 were tall but they even more severely mentally retarded than is usually the case. Nine other patients died aged between 3 and 23 years. The most common cause of death was cor pulmonale.

Adolescent↗
PubMedDate not supplied

In vivo measurement of hepatic iodine concentration using fluorescent excitation analysis.

Hepatic iodine concentration was measured in the live dog by external use of fluorescent excitation analysis. The number of characteristic photons produced by interaction of exciting radiation from an americium-241 source with iodine within the tissue is proportional to the tissue iodine concentrations. A correction is made for absorption of radiation by the abdominal wall and other tissues lying between the volume of liver being assayed and the detector collimator. The technique is applicable to the in vivo measurement of iodine concentrations from 0.5 to 40 mg/g. Accuracy of the technique is approximately +/- 10%, which is within the range of variation in iodine concentration at various sites within the liver. Radiation dose is low, and radiolabeled tracer compounds need not be used.

Animals↗
PubMedDate not supplied

Recirculation of iopanoic acid after conjugation in the liver.

The purpose of the investigation was to determine if an enterohepatic recirculation occurred for the metabolite of iopanoic acid. The major metabolite of iopanoic acid (Telepaque) in dog bile is the glucuronide conjugate. The identification and quantitation of glucuronide conjugate was accomplished by elemental analysis, paper chromatography, thin layer chromatography, fluorescent excitation analysis, and high pressure liquid chromatography. The stability of iopanoic acid glucuronide in refrigerated dog bile was confirmed. Known amounts of the glucuronide conjugate were instilled into the duodenum of 8 awake adult dogs, and bile collected for 8 hours. Between 19% and 53% (average 31%) of the administered dose was recovered in bile, thereby documenting the presence of an enterohepatic recirculation of conjugated iopanoic acid. The slow rise and plateau of the excretion curve suggests that either the compound is absorbed slowly, or that absorption depends upon deconjugation in the gut. The implications are discussed.

Animals↗