Browsing by Author "Orellana, P"

Now showing 1 - 3 of 3
  • No Thumbnail Available
    Item
    Captopril scintigraphy in the study of arterial hypertension in pediatrics
    (2004) Lagomarsino, E; Orellana, P; Muñoz, J; Velásquez, C; Cavagnaro, F; Valdés, F
    Renovascular hypertension (RVH) is responsible for 10% of arterial hypertension in children. The early diagnosis of RVH permits specific treatment leading to the cure of hypertension and avoidance of parenchymal damage. Captopril renal scintigraphy (CRS) provides information on the renovascular cause of the arterial hypertension. To validate the usefulness of CRS in hypertensive children, clinical, scintigraphic, and radiological data from 20 patients (mean age 6.1 +/- 5.5 years) were reviewed. Two patients were newborns. All had renal ultrasound scans and 9 had aortograms. In 7 children, RVH was confirmed by angiography, and CRS was positive for RVH in 6 of these. CRS was negative for RVH in 12 of 13 children without RVH. CRS was nondiagnostic in 3 children with abnormal baseline renal scintigraphy and severely decreased relative renal function (It;35%), 1 of whom had RVH. No side effects of captopril renography were observed. Captopril renography provides a logical, non-invasive, safe, and cost-effective approach in the evaluation of children suspected of having RVH.
  • No Thumbnail Available
    Item
    Dynamic instabilities in resonant tunneling induced by a magnetic field
    (1997) Orellana, P; Anda, E; Claro, F
    We show that the addition of a magnetic field parallel to the current induces self-sustained intrinsic current oscillations in an asymmetric double barrier structure. The oscillations are attributed to the nonlinear dynamic coupling of the current to the charge trapped in the well, and the effect of the external field over the local density of states across the system. Our results show that the system bifurcates as the field is increased, and may transit to chaos at large enough fields.
  • Thumbnail Image
    Item
    Relationship between acute pyelonephritis, renal scarring, and vesicoureteral reflux - Results of a coordinated research project
    (SPRINGER, 2004) Orellana, P; Baquedano, P; Rangarajan, V; Zhao, JH; Eng, NDC; Fettich, J; Chaiwatanarat, T; Sonmezoglu, K; Kumar, D; Park, YH; Samuel, AM; Sixt, R; Bhatnagar, V; Padhy, AK
    Acute pyelonephritis (APN) may produce permanent renal damage (PRD), which can subsequently lead to diverse complications. We prospectively evaluated 147 females and 122 males (mean age 3.5 years) with APN in order to analyze the relationship between the presence of PRD, at the time of cortical renal scintigraphy, and age, gender, episodes of urinary tract infection (UTI), and presence of vesicoureteral reflux (VUR). There were 152 children studied after the first proven UTI. VUR was present in 150 children. PRD was observed in 170 children. There were no significant differences between boys and girls. PRD was found in 36.4% of children younger than I year and in 70.1% of those older than I year (P<0.0001). Of children with VUR, 72% had PRD compared with 52% of children without VUR (P<0.0001). Of children with a first episode of UTI, 55.9% developed PRD as did 72.6% of those with recurrent UTI (P=0.004). Our results showed that PRD in children with APN is important, especially in the presence of VUR, recurrent UTI, and older age.