P-298: Screening of adolescent hypertension, and evaluation of target organ damages. Results from the Debrecen hypertension study

We performed a cross-sectional, population-based survey in Debrecen. All high school attending youths (a total sample of 10359, average age was 16.2±1.0 years) participated in the study. Following a 10 minute rest, 3 repeated BP measurements were taken by a validated OMRON M4 devices. Subjects completed a demographic and lifestyle survey as well. The 50th, 90th and 95th percentile value of the BP were defined by dividing the adolescent population into age-, gender- and height-specific subgroups. In comparison with US guidelines, in our sample, the systolic BP of boys in the different subgroups was 6 to 11 mmHg higher, while this difference was less marked for girls (1 to 5 mmHg). There were no marked differences in diastolic BP. With the help of a multiplex regression model we analyzed factors influencing BP. At systolic BP gender (β=0.373) and BMI(β=0.261) had a largest relative weight, while age (β=0.043), father's hypertension (β=0.042) and mother's hypertension (β=0.38) had a smaller, but also significant importance. BMI (β=0.264), gender (β=0.097), age (β=0.052), father's HTN (β=0.041) and mother's HTN (β=0.038) were predictive of diastolic BP. Adjusted R2 was 0.281 at systolic, and 0.181 at diastolic BP. Systolic and/or diastolic BP exceeded the age, gender and height adjusted 90th percentile of 1614 (15.84%) adolescents. Performing 2x3 extra measurements on this sample, 2.34% of the subjects had confirmed HTN. Target organ damage was observed in numerous cases: left ventricular hypertrophy in 13%, retinopathy in 12% and microalbuminuria in 10% of hypertensives. IMT in the common carotid artery was higher in hypertensive adolescents (means±SD: 0.55±0.11 mm) than in healthy control subjects (0.48±0.08 mm, p<0.001). Similar to this, a higher LVMI was measured in hypertensive (102.7±30.5 g/m2), than in healthy teenagers (91.1±25.2 g/m2, p<0.01). The screening of high blood pressure is important in adolescence also, because of the prevalence and the target organ damages. Early diagnosis of hypertension and follow-up may lead to the prevention of target organ damage

Measuring the deformation of a ferrogel sphere in a homogeneous magnetic field

A sphere of a ferrogel is exposed to a homogeneous magnetic field. In accordance to theoretical predictions, it gets elongated along the field lines. The time-dependence of the elastic shear modulus causes the elongation to increase with time analogously to mechanic creep experiments, and the rapid excitation causes the sphere to vibrate. Both phenomena can be well described by a damped harmonic oscillator model. By comparing the elongation along the field with the contraction perpendicular to it, we can calculate Poisson's ratio of the gel. The magnitude of the elongation is compared with the theoretical predictions for elastic spheres in homogeneous fields.Comment: 5 pages, 8 figure