974 resultados para Z-R relation
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BACKGROUND: The prevalence of hyperuricemia has rarely been investigated in developing countries. The purpose of the present study was to investigate the prevalence of hyperuricemia and the association between uric acid levels and the various cardiovascular risk factors in a developing country with high average blood pressures (the Seychelles, Indian Ocean, population mainly of African origin). METHODS: This cross-sectional health examination survey was based on a population random sample from the Seychelles. It included 1011 subjects aged 25 to 64 years. Blood pressure (BP), body mass index (BMI), waist circumference, waist-to-hip ratio, total and HDL cholesterol, serum triglycerides and serum uric acid were measured. Data were analyzed using scatterplot smoothing techniques and gender-specific linear regression models. RESULTS: The prevalence of a serum uric acid level >420 micromol/L in men was 35.2% and the prevalence of a serum uric acid level >360 micromol/L was 8.7% in women. Serum uric acid was strongly related to serum triglycerides in men as well as in women (r = 0.73 in men and r = 0.59 in women, p < 0.001). Uric acid levels were also significantly associated but to a lesser degree with age, BMI, blood pressure, alcohol and the use of antihypertensive therapy. In a regression model, triglycerides, age, BMI, antihypertensive therapy and alcohol consumption accounted for about 50% (R2) of the serum uric acid variations in men as well as in women. CONCLUSIONS: This study shows that the prevalence of hyperuricemia can be high in a developing country such as the Seychelles. Besides alcohol consumption and the use of antihypertensive therapy, mainly diuretics, serum uric acid is markedly associated with parameters of the metabolic syndrome, in particular serum triglycerides. Considering the growing incidence of obesity and metabolic syndrome worldwide and the potential link between hyperuricemia and cardiovascular complications, more emphasis should be put on the evolving prevalence of hyperuricemia in developing countries.
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The state-space approach is used to evaluate the relation between soil physical and chemical properties in an area cultivated with sugarcane. The experiment was carried out on a Rhodic Kandiudalf in Piracicaba, State of São Paulo, Brazil. Sugarcane was planted on an area of 0.21 ha i.e., in 15 rows 100 m long, spaced 1.4 m. Soil water content, soil organic matter, clay content and aggregate stability were sampled along a transect of 84 points, meter by meter. The state-space approach is used to evaluate how the soil water content is affected by itself and by soil organic matter, clay content, and aggregate stability of neighboring locations, in different combinations, aiming to contribute to a better understanding of the relation among these variables in the soil. Results show that soil water contents were successfully estimated by this approach. Best performances were found when the estimate of soil water content at locations i was related to soil water content, clay content and aggregate stability at locations i-1. Results also indicate that this state-space model using all series describes the soil water content better than any equivalent multiple regression equation.
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Numérisation partielle de reliure
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La forte teneur en elements siderophiles des sediments de la limite Cretace-Tertiaire suggere que les principaJes disparitions d'especes ont ete provoquees par des catastrophes cosmiques. Cette hypothese pourrait etre confirmee par la decouverte d'une anomaJie similaire it la limite Permien-Trias, caracterisee par la plus grave crise biologique du Phanerozoique. L'etude du site de Meishan, en Republique populaire de Chine, n'apporte aucune confirmation de ce scenario. Aucune trace d'iridium, Ie meilleur traceur de la matiere extraterrestre, n'a ete trouvee dans les 18 echantillons preleves au voisinage de la transition Permien-Trias. Toute relation entre la crise biologique du Permien-Trias et une catastrophe cosmique doit donc, pour l'instant, etre consideree comme hypothetique. The presence of siderophile-enriched material at the Cretaceous-Tertiary boundary suggests that the major extinctions of living species could result from cosmic catastrophes. The finding of the same kind of material at the Permian-Triassic boundary would be important to confirm the influence of cosmic phenomena on extinctions. The study of the M eishan section, in China, does not provide any support to this view. Iridium, the best tracer of cosmic material, has not been detected in any of the 18 samples collected around the boundary. A relation between the Permian-Triassic extinction and a cosmic collision therefore remains hypothetical.
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Numérisation partielle de reliure
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Oxygen consumption of collagenase-liberated rat adipocytes was measured by two different techniques: a microspectrophotometric method using hemoglobin as indicator of respiration and a technique using the oxygen electrode. These two completely different techniques gave similar values for oxygen consumption. With the spectrophotometric method, the oxygen consumption of single fat cells was determined. A close positive correlation (r = greater than 0.90) between oxygen consumption and fat cell size was observed in each tissue examined. With the oxygen electrode technique, oxygen consumption of adipocyte suspensions from young (40 days, 180 g) and old (90 days, 480 g) rats was examined. Fat cells of the suspensions were separated into classes of different size by a flotation technique. A significant positive correlation between fat cell size and oxygen consumption was observed in both young (r = 0.88) and old (r = 0.95) rats. However, the slope was much steeper in young rats. At a cell weight of 0.1 microgram the oxygen consumption was 0.364 and 0.086 microL O2/10(6) cells/min-1 in young and old rats, respectively. In the literature, a number of separate metabolic pathways have been found to be related positively to fat cell size and negatively to age. We conclude that these scattered metabolic observations are in agreement with integrated data on energy expenditure as evaluated from oxygen consumption. Estimations of the energy expenditure of adipose tissue indicates that this tissue is responsible for about 1% and 0.5% of the total energy expenditure in young and old rats, respectively.
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The isolation of the four Xenopus laevis vitellogenin genes has been completed by the purification from a DNA library of the B2 gene together with its flanking sequences. The overlapping DNA fragments analyzed cover 34 kilobases. The B2 gene which has a length of 17.5 kilobases was characterized by heteroduplex and R-loop mapping in the electron microscope and by in vitro transcription in a HeLa whole-cell extract. Its structural organization is compared with that of the closely related B1 gene. The mRNA-coding sequence of about 6 kilobases is interrupted 34 times in the B1 gene and 33 times in the B2 gene. Sequence homology between the two genes was not only found in exons. In addition, 54% of the intron sequences as well as 63% and 48.5% respectively of the 5' and 3' flanking sequences, show enough homology to form stable duplexes. These findings are compared with earlier results obtained with the two other closely related members of the vitellogenin gene family, the A1 and the A2 genes.