Browsing by Author "Villarroel, L."
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- ItemCompleteness of Chilean information on live births: design of a diagnostic instrument relating birth weight and gestational age at birth to neonatal mortality(ELSEVIER IRELAND LTD, 2006) Mardones, F. J.; Marshall, G.; Viviani, P.; Villarroel, L.; Tapia, J. L.; Cerda, J.; Garcia Huidobro, T.; Ralph, C.; Mardones Restat, F. J.
- ItemEmpiema pleural causado por tricomonas. Caso clínico(2010) Ramírez, A.; Palma, A.; Aviles, E.; Villarroel, L.Pleural empyema formation is one of the potential complications of lower respiratory tract infections and it is characterized by bacterial organisms seen on gram stain or the aspiration of pus on thoracentesis. Very rarely empyema can be caused by trichom
- ItemGenetic variation in P450c11AS in Chilean patients with low renin hypertension(ENDOCRINE SOC, 1996) Fardella, C.E.; Rodriguez, H.; Montero, J.; Zhang, G.R.; Vignolo, P.; Rojas, A.; Villarroel, L.; Miller, W.L.Low renin hypertension (LRH), which accounts for 10-20% of patients with idiopathic ''essential'' hypertension, bears hormonal similarities to mineralocorticoid-induced hypertension, but elevated mineralocorticoid concentrations have not been found. Some patients with LRH have normal, rather than suppressed, plasma aldosterone concentrations, so that the ratio of aldosterone concentration to PRA (Aldo/PRA) is high, suggesting inappropriately increased aldosterone biosynthesis. We characterized the CYP11B2 gene that encodes the aldosterone synthase, P450c11AS, in hypertensive and control populations in a single clinic in Santiago, Chile. We directly sequenced the entire CYP11B2 gene in 12 patients with LRH, 2 high renin hypertensive controls, and 2 normotensive controls. All sequences were identical, except that 8 of 24 LRH alleles encoded arginine rather than lysine at position 173. The Arg(173) and Lys(173) variants were expressed in transfected MA-10 cells, and their ability to convert deoxycorticosterone to aldosterone was measured; the apparent Michaelis constant (K-m) for Lys(173) was 2.73 mu mol/L; the K-m for Arg(173) was 2.53 mu mol/L. The apparent maximal velocity (V-max) for Lys(173) was 6.5x10(-3) mu g/mL . 24 h; the V-max for Arg(173) was 7.8x10(-3) mu g/mL . 24 h. The first order rate constant, V-max/K-m was 2.38 for Lys(173) and 3.08 for Arg(173). As these values were not significantly different, we sought to determine whether Arg(173) is a polymorphism linked to LRH. We examined position 173 in 52 unselected patients with idiopathic hypertension and 55 normotensive controls by PCR amplification of CYP11B2 exons 3-5 followed by digestion with Bsu36I, which digests the Arg(173) sequence, but not the Lys(173) sequence. More of the hypertensive alleles (39 of 104, 37.5%) than normotensive alleles (25 of 110, 22.5%) carried Arg(173) (chi(2)=5.57; P <0.02). Most of the Arg(173) alleles (31 of 72, 43.1%) were from hypertensive patients with Aldo/PRA below 30, whereas only 5 of 24 (20.8%) Arg(173) alleles were found in patients with Aldo/PRA greater than 30 (chi(2)=3.79; P=0.05) Thus, the Arg(173) variant of CYP11B2 may be linked to LRH in Chilean patients.
- ItemHistorical exposure to arsenic in drinking water and risk of late fetal and infant mortality - Chile 1950-2005(2014) Ríos, P.; Cortés, S.; Villarroel, L.; Ferreccio, C.A previous study comparing two Chilean cities demonstrated significant increase in fetal mortality in relation to increase in arsenic (As) exposure. Our aim was to confirm this association increasing size and variation of the comparison group, extending the time interval and measuring additional potential confounders. We used time series analysis of infant mortality indicators. We confirmed the clear excess of risk of late fetal death following the increase of the As concentration in drinking water, and the rapid return to the baseline mortality rate in response to the removal of arsenic after 1973. The effect was lower for neonatal and post-neonatal mortality. This study confirms that fetus is more sensitive to As and that regulations should consider additional protection for pregnant women and small children.
- ItemMicrosatellite instability and loss of heterozygosity have distinct prognostic value for testicular germ cell tumor recurrence(TAYLOR & FRANCIS INC, 2004) Velasco, A.; Riquelme, E.; Schultz, M.; Wistuba, I.I.; Villarroel, L.; Koh, M.S.; Leach, F.S.Germ cell tumor (GCT) is the most common genitourinary malignancy of men between the ages of 18 and 35 years. Therapy is ultimately successful in over 90% of patients, however significant morbidity and mortality can be associated with adjuvant treatment and relapse. Molecular markers that predict treatment response and/or poor outcome would have immediate clinical benefit since adjuvant treatment could be selectively reserved for patients at higher risk for relapse and those patients most likely to respond to treatment. In order to identify potential prognostic molecular markers, we evaluated 118 GCT for microsatellite instability (MSI), loss of heterozygosity (LOH) and MSH2 immunostaining to identify tumors associated with relapse and/or poor outcome following initial surgical, medical and/or radiation therapy.
- ItemPrenatal growth and metabolic syndrome components among Chilean children(CAMBRIDGE UNIV PRESS, 2012) Mardones, F.; Villarroel, L.; Arnaiz, P.; Barja, S.; Dominguez, A.; Castillo, O.; Farias, M.; Eriksson, J. G.; Pacheco, P.The association of prenatal growth with metabolic syndrome (MS) components and insulin resistance (IR) in children has not been studied in Chile and most developing countries. Some associations found in developed countries are controversial. A retrospective cohort study was designed linking present information on MS components and IR in children with register-based information on birth weight (BW), birth length (BL) and gestational age (GA). Examinations included anthropometry and blood pressure (BP), as well as self-report of pubertal status. A fasting blood sample was taken to determine lipids, glucose, insulin and homeostasis model assessment (HOMA)-IR was calculated. The study cohort of 2152 children was on average 11.4 +/- 1.0 years old. The prevalence of MS, IR and overweight were 7.6%, 24.5% and 34%, respectively. Elevated BP was negatively associated with dichotomized risk categories of the perinatal factors studied (BW, BL and GA). Contingency tables showed that high waist circumference (WC) and elevated BP had a U-shaped association with various categories of BW and BL, respectively. Stepwise linear regressions selected: (a) WC as inversely associated to GA and directly associated to BW, (b) BP as inversely associated to GA and (c) HOMA-IR as inversely associated to BL. Non-optimal prenatal growth seems to predispose to high WC, elevated BP and IR in school-age children, supporting the early life origin of several non-communicable diseases. Those associations were rather weak as estimated by the slopes of the regressions and probably reduced by their U-shaped nature; they would reasonably become stronger with a longer follow-up.
- ItemSocial capital and self-rated health in urban low income neighbourhoods in Chile(BMJ PUBLISHING GROUP, 2008) Sapag, J. C.; Aracena, M.; Villarroel, L.; Poblete, F.; Berrocal, C.; Hoyos, R.; Martinez, M.; Kawachi, I.Objective: To examine the potential association between social capital and self-rated health within a low income community of Santiago, Chile.