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    Effects of losartan treatment on T-cell activities and plasma leptin concentrations in primary hypertension
    (Sage Publications Ltd, 2001) Sönmez, A.; Kısa, Ü.; Uckaya, G.; Eyileten, T.; Cömert, B.; Koç, B.; Özata, M.
    Recent evidence shows that leptin may contribute to elevated blood pressure (BP) and interact with die renin-angiotensin-aldosterone and cellular immune systems. Altered T-cell activities and changes in T-cell si ratios have also been reported in hypertension. However, little is known about the effects of AT(1)-receptor antagonism on T-cell activities and plasma leptin concentrations in primary hypertension. We have, therefore, investigated the relationship between leptin and T-cell activities and the effect of an AT(1)-receptor antagonist, losartan, in primary, hypertension. Twenty recently-diagnosed and untreated young adults (11 males and 9 females, age; 39.9 +/- 7.6 years, range 23-49 years, BMI; 27.6 +/- 3.7 kg/m(2)) and 20 normotensive healthy, age-, sex- and BMI-matched controls were studied. The [H-3]-thymidine uptakes of cultured lymphocytes were determined, both spontaneously and after stimulation,with phytohaemagglutinin. The tests were performed before mid after three months of treatment with losartan. The results indicate that the blastogenic responses of T-cells to phytohaemagglutinin are significantly higher in the patient group compared with controls (p=0.02). After normalisation of BP. T-cell responses were significantly reduced and were lower than in the controls (P=0.01). Pretreatment plasma leptin levels were significantly higher in hypertensives than in controls (P=0.01). However, losartan treatment had no significant effect on leptin concentrations; moreover, no correlation between leptin levels and T-cell activity was found. Our data show that plasma leptin levels and T-cell activity are markedly enhanced in untreated essential hypertension and that die alteration of T-cell activity is not related to plasma leptin levels. Antihypertensive treatment with losartan decreases T-cell activities but does not influence plasma leptin levels. We conclude that leptin levels are not affected by AT(1)-receptor blockade and are not related to T-cell activity.
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    A piezoelectric motor using two orthogonal bending modes of a hollow cylinder
    (Ieee-Inst Electrical Electronics Engineers Inc, 2002) Koç, B.; Cağatay, S.; Uchino, K.
    This paper proposes a compact ultrasonic motor with low manufacturing costs, a simpler driving circuit, and scalability. The stator of the motor presented in this paper consists of a hollow metal cylinder, whose outside surface was flattened on two sides at 90 degrees to each other, on which two rectangular piezoelectric plates were bonded. Because the cylinder has a partially square/partially circular outside surface, the stator has two degenerated bending modes that are orthogonal to each other. A wobbling motion is generated on the cylinder when only one piezoelectric plate is excited at a frequency between the two orthogonal bending modes. A rod through a pair of ferrules was used as the rotor of this motor. The prototype motor, whose stator was 2.4 mm in diameter and 10 mm in length, operated at 69.5 kHz, was experimentally characterized, and a maximum torque of 1.8 mNm was obtained.