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Biomedical subjects

J Duarte

Publications and source records attributed to J Duarte.

At least 19 recordsLinked to original sources
PubMed2002

Factors affecting somatic cell counts and their relations with milk and milk constituent yield in buffaloes.

Data concerning daily milk yield (MY), percentage of milk fat (%F), protein (%P), lactose (%LT), and total solids (%TS), and somatic cell counts (SCC) for a herd of 222 Murrah buffalo reared in the state of São Paulo, Brazil, were collected monthly from 1997 to 2000 in order to study the factors affecting SCC and their relation to milk production and constituents during lactation. SCC decreased in the second month of lactation and increased thereafter, up to the ninth month of lactation. The interaction of month of lactation x order of calving was significant. Mean MY observed during the first month of lactation was 6.87 kg, which increased to 7.65 kg during the second month, and then decreased until the ninth month of lactation (3.83 kg). During the different months of lactation, %F, %P, %LT, and %TS ranged from 6.28 to 8.38%, 4.05 to 4.59%, 4.96 to 5.34%, and 16.94 to 18.55%, respectively. Calving year, calving order, and order of month of lactation significantly affected MY, %F, %P, %LT, and %TS. The regression coefficients of transformed SCC on MY and %LT were negative and significant during all months of lactation, showing that milk and lactose yield decreased with increased transformed SCC, causing losses to buffalo milk producers.

Animals↗
PubMed2002

Relationship between cardiorespiratory fitness, body composition and blood pressure in school children.

BACKGROUND: The purpose of this comparative and correlational cross-sectional study was to describe the associations between cardiorespiratory fitness, blood pressure and body composition in Portuguese school children. METHODS: The sample comprised 529 children (246 males and 283 females) aged 8-15 years-old. Body height and body mass were determined by standard anthropometric METHODS: Blood pressures were measured with children sitting after at least 5 min rest. The maximal multistage 20 m shuttle run test was carried-out to predict maximal aerobic power. RESULTS: The present study shows that boys were more fit (p= or <0.05) and less fat than girls (p= or <0.05). Multiple regression analysis reveals that weight and age explained significantly (p= or <0.01) the amounts of systolic blood pressure (SBP) and diastolic blood pressure (DBP). In girls, percentage of fat (%F) showed an influence on the variance in SBP (4.9%, p= or <0.05). In addition, weight (14.5%) and age (9.8%) account significantly (p= or <0.01) for the amount of variance to DBP in males. For girls, age (11.4%) and BMI (2.4%) account significantly to the variance found in DBP. However, the independent variables, for both sexes, account less than 50% of the overall variance found in blood pressures values. CONCLUSIONS: In conclusion, the present study shows that boys were more fit and had less fat than girls. The level of cardiorespiratory fitness does not seem to be an important correlate of blood pressure variation across age groups and gender.

Adolescent↗
PubMed2002

Patients with severe acute pancreatitis should be more often treated in an Intensive Care Department.

BACKGROUND: Acute pancreatitis (AP) is a serious disease with a frustrating mortality rate, but with a very good quality of life reported among survivors, that justifies an optimised allocation of therapy intensity. PURPOSE: To audit monitoring and treatment of severe AP in our Intensive Care Department based upon Atlanta severity classification and following recommendations. METHODS: Retrospective study of all AP admitted to our ICU between 1st January, 1993 and 31st December, 1999 in a tertiary University Hospital in Northern Portugal. RESULTS: Our sample (n = 44) represents less than 1% of all patients observed in our ICU and approximately 3% of all patients with AP admitted to our Hospital between 1993 and 1999. All cases fulfilled at least one Atlanta criteria of severe AP. Mean length of stay was 11.6 days. Diagnosis of AP was established in less than 48 hours in 86% of cases: amylasemia and lypasemia were determined in 84 and 7%, respectively and 64% of cases were submitted to ultrasonography. The median time between diagnosis and ICU admission was 2 days. Biliary calculus was responsible for 38% of cases and ethanol for 14%: Thirty-six per cent were considered idiopathic (in none was ERCP performed). Concerning local complications, necrosis was diagnosed in 56% and pseudocysts or abscesses in 23%. Infection was diagnosed by US/CT guided punction or by the presence of gas in CT (performed in 83% during the first ten days of disease) in 18% of the cases. 68% were put on parenteral nutrition (beginning on the 2nd day after admission to ICU in 50% of patients); and 51% had enteric feeding (median day of start = 8.5 days). Antibiotics were prescribed in 91%. Forty-five per cent of patients were submitted to surgery (median day of surgery was 6 days). No statistically significant differences were found concerning local or systemic complications according to different therapies. Mortality rate in our ICU was 36%, mostly during first and second weeks. Patients admitted to ICU later than the second day after diagnosis seem to die earlier (P < 0.005). Outcome (death) was statistically related with organ dysfunction criteria, namely Atlanta criteria (renal failure), SOFA and proportion of days with organ dysfunction. CONCLUSIONS: In our Institution (a tertiary hospital) AP diagnosis is quickly made, local and systemic complications are clearly diagnosed and monitored, but at least 50% of patient waited for 2 days until ICU admission, representing those who die earlier.

Acute Disease↗
PubMed2001

Community acquired pneumonia among pediatric outpatients in Salvador, Northeast Brazil, with emphasis on the role of pneumococcus.

Pneumonia is one of the leading causes of hospitalization and death among children in developing countries, and mortality due to pneumonia has been associated with S. pneumoniae infection. This investigation was designed to describe the antimicrobial susceptibility and serotype patterns of pneumococcal strains recovered from the blood of children with community-acquired pneumonia (CAP) and to assess the clinical findings of pneumococcal bacteremic patients with pneumonia. In a 26 month prospective study, blood cultures were obtained as often as possible from children (<16 years of age) diagnosed with CAP in two emergency rooms. Antimicrobial drug susceptibility tests and serotyping were performed when pneumococcus was identified. We studied 3,431 cases and cultured blood samples from 65.5% of those. Pneumococcus was recovered from 0.8% of the blood samples. The differences in age, somnolence, wheezing and hospitalization among children with and without pneumococcal bacteremia were statistically significant. Pneumococcal bacteremia was age-related (mean 1.63 +/- 1.55; median 0.92) and associated with somnolence and hospitalization among children with CAP. One strain was recovered from pleural fluid. Penicillin resistance was detected in 21.0% (4/19) of the strains at an intermediate level, whereas 63.0% of the strains were resistant to trimethoprim-sulfamethoxazole. The most common serotypes were 14 and 6B, and these serotypes included the resistant strains. Eight of our 18 isolates from blood were of types included in the heptavalent conjugate pneumococcal vaccine, recently licensed in the USA.

Adolescent↗
PubMed2001

Effects of chronic quercetin treatment on hepatic oxidative status of spontaneously hypertensive rats.

The effects of chronic administration of an oral daily dose of quercetin (10 mg Kg(-1)), the most abundant dietary flavonoid, were investigated on hepatic oxidative status in spontaneously hypertensive rats and normotensive Wistar Kyoto rats. Decreased liver glutathione peroxidase activity, increased liver total glutathione levels and increased both hepatic and plasmatic malondialdehyde concentrations were observed in spontaneously hypertensive rats when compared to Wistar Kyoto rats. In spontaneously hypertensive rats, treatment with quercetin for 5 weeks reduced blood pressure, increased glutathione peroxidase activity and reduced both plasma and hepatic malondialdehyde levels. However, none of these effects were observed in Wistar Kyoto rats. In conclusion, quercetin shows both antihypertensive and antioxidant properties in this model of genetic hypertension.

Animals↗
PubMed2001

Dietary vitamin E supplementation protects the rat large intestine from experimental inflammation.

Vitamin E, the most potent antioxidant in the lipid phase, was tested for antiinflammatory activity in trinitrobenzenesulfonic acid-induced rat colitis. Rats were fed a nonpurified diet (saline and control groups) or a vitamin E supplemented diet (treated group, 300 mg/kg nonpurified diet). Vitamin E supplementation, which resulted in increased colonic vitamin E levels, reduced colonic weight and damage score, prevented lipid peroxidation and diarrhea, reduced interleukin-1 beta levels and preserved glutathione reductase activity and total glutathione levels. However, it did not modify myeloperoxidase levels, which are indicative of neutrophil infiltration in the inflamed colon. Vitamin E protects the rat colon from oxidative stress associated with inflammation.

Animals↗
PubMed2001

Antihypertensive effects of the flavonoid quercetin in spontaneously hypertensive rats.

1. The effects of an oral daily dose (10 mg kg(-1)) of the flavonoid quercetin for 5 weeks in spontaneously hypertensive (SHR) and normotensive Wistar Kyoto rats (WKY) were analysed. 2. Quercetin induced a significant reduction in systolic (-18%), diastolic (-23%) and mean (-21%) arterial blood pressure and heart rate (-12%) in SHR but not in WKY rats. 3. The left ventricular weight index and the kidney weight index in vehicle-treated SHR were significantly greater than in control WKY and these parameters were significantly reduced in quercetin-treated SHR in parallel with the reduction in systolic blood pressure. 4. Quercetin had no effect on the vasodilator responses to sodium nitroprusside or to the vasoconstrictor responses to noradrenaline or KCl but enhanced the endothelium-dependent relaxation to acetylcholine (E(max)=58+/-5% vs 78+/-5%, P<0.01) in isolated aortae. 5. The 24 h urinary isoprostane F(2 alpha) excretion and the plasma malonyldialdehyde (MDA) levels in SHR rats were increased as compared to WKY rats. However, in quercetin-treated SHR rats both parameters were similar to those of vehicle-treated WKY. 6. These data demonstrate that quercetin reduces the elevated blood pressure, the cardiac and renal hypertrophy and the functional vascular changes in SHR rats without effect on WKY. These effects were associated with a reduced oxidant status due to the antioxidant properties of the drug.

Acetylcholine↗
PubMed2001

Vasorelaxant effects of the bioflavonoid chrysin in isolated rat aorta.

Chrysin relaxed the contractions induced by noradrenaline in isolated endothelium-intact rat aortic rings (IC(50) = 16 +/- 4 microM). Endothelium removal and N(G)-nitro-L-arginine methyl ester inhibited this relaxant effect. Chrysin potentiated the relaxation to acetylcholine under control conditions or after incubation with the superoxide anion generator hypoxanthine/xanthine oxidase. It also potentiated the relaxation induced by 3-morpholino-sydnonimine, sodium nitroprusside, and 8-bromoguanosine-3':5'-cyclic-monophosphate. Therefore, vasorelaxation induced by chrysin in the rat aorta is endothelium- and NO-dependent. This effect is mediated by the prevention of O(2)(-)-induced inactivation of endothelial derived NO and also by the potentiation of cGMP-induced vasodilatation.

Animals↗
PubMed2001

Guillain-Barré syndrome in Spain, 1985-1997: epidemiological and public health views.

Retrospective demographic information and hospital record data were collected for 337 patients resident in Spain who had validated Guillain-Barré syndrome (GBS) diagnoses and clinical onset during the period 1985-1997 and had been admitted to 11 centres, covering a population of 3.9 million. The European age-adjusted GBS incidence per 100,000 for 1985-1997 among the population aged 20 and over was 0.85, with a breakdown of 1.14 in men and 0.58 in women. Incidence increased with age and time, with occasional rises that mimicked outbreaks and occurred at irregular 2- to 4-year intervals, mainly in winter. Spatial variation was modest. Respiratory and gastrointestinal infections respectively constituted 49.3 and 19.3% of recorded preceding events. The 97.5% intercentile limit, obtained from the 1985-1997 monthly incidences using predictions from a Poisson model, was proposed as the threshold value for pilot epidemiological surveillance of GBS in 1998-1999.

Adult↗
PubMed2000

Electroelution as a simple and fast protein purification method: isolation of an extracellular xylanase from Bacillus sp. CCMI 966.

An efficient and simple modified method of electroelution is described that can be used as a time-saving method for eluting multiple protein bands. Provided that the proteins are highly expressed, they can be purified rapidly and without requiring any prior knowledge of the protein characteristics. A xylanase excreted by Bacillus sp. CCMI 966 was purified directly from the polyacrylamide gel. Some of the properties of this enzyme are presented. It had an unusually apparent high molecular mass of 340kDa, as determined by native PAGE. The specific activity of the purified xylanase was 137 U/mg.

Journal Article↗
PubMed2000

Cardiovascular effects of visnagin on rats.

The present article describes the effects of visnagin on systolic blood pressure and heart rate in the anaesthetized rat. Intravenous administration of visnagin (0.3-5 mg kg-1) produced dose-related decreases in blood pressure with no significative changes in heart rate. Under nitric oxide synthase inhibition (L-NAME, 50 mg kg-1) the hypotensive effects of visnagin (5 mg kg-1) were not affected. Visnagin (5 x 10(-6) M-10(-4) M) produced a weak decrease in the rate and amplitude of spontaneous contractions in right atria. Visnagin also caused a weak decrease in peak contractile force and the df/dtmax with no significant changes in the time to peak tension or the time for total contraction in left atria driven at a basal rate of 1 Hz. Visnagin (10(-5) M, 5 x 10(-5) M and 10(-4) M) concentration-dependently decreased pressor response to KCl (IC50 = 5.1 +/- 2.5 x 10(-5) M) and noradrenaline (IC50 = 2.6 +/- 0.9 x 10(-5) M) in rat isolated mesenteric beds. Visnagin (3 x 10(-7) M-10(-4) M) induced a concentration-dependent relaxation of isolated mesenteric arteries contracted by noradrenaline (IC50 = 1.7 +/- 0.8 x 10(-5) M). The relaxant effects in the absence of functional endothelium were not significantly different (IC50 = 1.5 +/- 0.3 x 10(-5) M, P > 0.05) from those observed in segments with intact endothelium. In conclusion, the main mechanism responsible for the acute hypotensive effect of visnagin is the vasorelaxant response induced by this drug in resistance arteries.

Animals↗
PubMed2000

Involvement of protein kinase C, tyrosine kinases, and Rho kinase in Ca(2+) handling of human small arteries.

The mechanisms of Ca(2+) handling and sensitization were investigated in human small omental arteries exposed to norepinephrine (NE) and to the thromboxane A(2) analog U-46619. Contractions elicited by NE and U-46619 were associated with an increase in intracellular Ca(2+) concentration ([Ca(2+)](i)), an increase in Ca(2+)-independent signaling pathways, or an enhancement of the sensitivity of the myofilaments to Ca(2+). The two latter pathways were abolished by protein kinase C (PKC), tyrosine kinase (TK), and Rho-associated protein kinase (ROK) inhibitors. In Ca(2+)-free medium, both NE and U-46619 elicited an increase in tension that was greatly reduced by PKC inhibitors and abolished by caffeine or ryanodine. After depletion of Ca(2+) stores with NE and U-46619 in Ca(2+)-free medium, addition of CaCl(2) in the continuous presence of the agonists produced increases in [Ca(2+)](i) and contractions that were inhibited by nitrendipine and TK inhibitors but not affected by PKC inhibitors. NE and U-46619 induced tyrosine phosphorylation of a 42- or a 58-kDa protein, respectively. These results indicate that the mechanisms leading to contraction elicited by NE and U-46619 in human small omental arteries are composed of Ca(2+) release from ryanodine-sensitive stores, Ca(2+) influx through nitrendipine-sensitive channels, and Ca(2+) sensitization and/or Ca(2+)-independent pathways. They also show that the TK pathway is involved in the tonic contraction associated with Ca(2+) entry, whereas TK, PKC, and ROK mechanisms regulate Ca(2+)-independent signaling pathways or Ca(2+) sensitization.

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗
PubMed1999

Cardiovascular effects of captopril and enalapril in obese Zucker rats.

The effects of two weeks of oral administration of the angiotensin-converting enzyme inhibitors captopril (a sulphydryl-containing drug) and enalapril (which lacks the sulphydryl group) on skeletal muscle glucose uptake, arterial blood pressure, cardiac hypertrophy, proteinuria and aortic vascular reactivity in obese Zucker rats were evaluated. Captopril (50 mg kg(-1) once daily) and enalapril (10 mg kg(-1) did not modify body weight gain or food or water intake. Both drugs decreased systolic blood pressure (157+/-6, 133+/-4 and 136+/-3 mm Hg, in vehicle-, captopril- and enalapril-treated rats, respectively), blood glucose (172+/-8 vs. 151+/-7 and 158+/-5 mg dl(-1), respectively), proteinuria (46+/-10 vs. 17+/-2 and 18+/-2.5 mg dl(-1), respectively) and heart weight (2.17+/-0.03, 1.98+/-0.02 and 1.99+/-0.04 mg g(-1)of body weight, respectively). Plasma insulin concentration was significantly increased by enalapril (17+/-2 ng ml(-1) vs. 9+/-2) but not by captopril (12+/-1). In the absence of insulin, the diaphragms from captopril- or enalapril-treated rats showed a significantly higher glucose uptake than that of controls (31% and 30% vs. control group, respectively). The presence of insulin in the incubation medium did not stimulate peripheral glucose uptake in the control group but significantly increased glucose uptake in diaphragms from captopril- or enalapril-treated rats (enhancement of glucose uptake vs. control: 52% and 43%, respectively). Endothelium-intact aortic rings from control Zucker rats showed a poor relaxant response to acetylcholine (maximal relaxation of 38.4+/-4.7%). Captopril significantly improved the endothelium-dependent vascular relaxation responses to acetylcholine and the endothelium-independent relaxation to the nitric oxide donor sodium nitroprusside whereas enalapril did not modify these relaxant responses. Neither captopril nor enalapril significantly affected the vascular contractile responses to the vasoconstrictors noradrenaline or KCl. In conclusion, the angiotensin-converting enzyme inhibitors captopril and enalapril reversed insulin resistance and the associated cardiovascular complications (cardiac hypertrophy, hypertension and proteinuria) in the obese Zucker rat, an animal model of non-insulin-dependent (type II) diabetes mellitus. However, only captopril, but not enalapril, improved the impaired endothelium-dependent and independent relaxant responses in the isolated rat aorta.

Acetylcholine↗
PubMed1999

Effects of visnagin on cyclic nucleotide phosphodiesterases and their role in its inhibitory effects on vascular smooth muscle contraction.

1. Visnagin relaxed aortae previously contracted by noradrenaline. This effect was unalterated by endothelium removal and potentiated, at high concentrations, by the previous incubation with sodium nitroprusside. 2. Visnagin weakly inhibited the hydrolytic activity of the cyclic nucleotide phosphodiesterase (PDE) isozymes (PDE5, PDE4, PDE3, cyclic GMP activated PDE2 and PDE1). 3. The present results indicate an involvement of PDE inhibition in the relaxant effect of visnagin at high concentration (>5x10(-5) M).

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1999

Involvement of thromboxane A2 in the endothelium-dependent contractions induced by myricetin in rat isolated aorta.

1. The present study was undertaken to analyse the mechanism of the contractile response induced by the bioflavonoid myricetin in isolated rat aortic rings. 2. Myricetin induced endothelium-dependent contractile responses (maximal value=21+/-2% of the response induced by 80 mM KCl and pD2=5.12+/-0.03). This effect developed slowly, reached a peak within 6 min and then declined progressively. 3. Myricetin-induced contractions were almost abolished by the phospholipase A2 (PLA2) inhibitor, quinacrine (10 microM), the cyclo-oxygenase inhibitor, indomethacin (10 microM), the thromboxane synthase inhibitor, dazoxiben (100 microM), the putative thromboxane A2 (TXA2)/prostaglandin endoperoxide receptor antagonist, ifetroban (3 microM). These contractions were abolished in Ca2+-free medium but were not affected by the Ca2+ channel blocker verapamil (10 microM). 4. In cultured bovine endothelial cells (BAEC), myricetin (50 microM) produced an increase in cytosolic free calcium ([Ca2+]i) which peaked within 1 min and remained sustained for 6 min, as determined by the fluorescent probe fura 2. This rise in [Ca2+]i was abolished after removal of extracellular Ca2+ in the medium. 5. Myricetin (50 microM) significantly increased TXB2 production both in aortic rings with and without endothelium and in BAEC. These increases were abolished both by Ca2+-free media and by indomethacin. 6. Taken together, these results suggests that myricetin stimulates Ca2+ influx and subsequently triggers the activation of the PLA2 and cyclo-oxygenase pathways releasing TXA2 from the endothelium to contract rat aortic rings. The latter response occurs via the activation of Tp receptors on vascular smooth muscle cells.

Animals↗