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    Comparison of Ischemic Side Effects of Levosimendan and Dobutamine with Integrated Backscatter Analysis
    (John Wiley & Sons Inc, 2009) Duygu, Hamza; Nalbantgil, Sanern; Zoghi, Mehdi; Ozerkan, Filiz; Yildiz, Ahmet; Akilli, Azem; Akin, Mustafa
    Background: Levosimendan improves cardiac contractility without increasing oxygen consumption. However, its effects on ischemia were not supported with the utilization of a noninvasive parameter of myocardial characterization. Hypothesis: The changes observed in integrated backscatter (IBS) may be reflective of change in myocardial ischemia. In this study, the effect of levosimendan on ischemia detected by IBS was evaluated in patients with ischemic heart failure (HF). Methods: Patients who had LVEF <40% and NYHA III-IV symptoms of HF were included in this study. Patients were randomized to levosimendan (n = 21), or to dobutamine (n = 25) groups. The cyclic variation of integrated backscatter (CVIBS) was determined as the difference between the maximal and minimal values in a cardiac cycle.. average of three consecutive beats. CVIBS was taken from the mid-anteroseptal, mid-inferior, and mid-posterolateral areas of the parasternal short axis images before the drug administration and at the end of the 24-hour infusion period. Results: Baseline characteristics and concomitant medications were similar in both groups. A significant reduction in CVIBS was detected in anteroseptal (7.6 +/- 1.4 dB versus 5.9 +/- 0.8 dB, p = 0.01), inferior watt (7.4 +/- 0.8 dB versus 6.7 +/- 1.5 dB, P = 0.03), and posterolateral wall (9.0 +/- 1.2 dB versus 8.2 +/- 0.6 dB, P = 0.04) after dobutamine administration, while no significant changes were observed in the levosimendan group in all walls. Conclusions: Unlike dobutamine, levosimendan may not induce myocardial ischemia as shown by CVIBS at commonly used dosages in the setting of decompensated HF without active ischemia.
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    Exergetic performance assessment of solar photovoltaic cell (PV) assisted earth to air heat exchanger (EAHE) system for solar greenhouse cooling
    (Elsevier Science Sa, 2011) Yildiz, Ahmet; Ozgener, Onder; Ozgener, Leyla
    An experimental system was developed and tested in order to investigate the exergetic performance of a solar photovoltaic system (PV) assisted earth-to-air heat exchanger (under ground air tunnel) that is used for greenhouse cooling at the Solar Energy Institute, Ege University, Izmir, Turkey. This system was under operational conditions successfully during the 2010 summer cooling season. This paper provides the experimental results obtained between 18th of August and 26th of August of in 2010. Exergy destruction in the system was calculated and presented in this paper using a reference temperature of 15 degrees C. Results are discussed and interpreted in the paper for various performance metrics, such as the effect of climatic conditions and operating conditions on the system performance. Results show that the system may be satisfactorily used for greenhouse cooling in the Mediterranean and Aegean regions of Turkey. (C) 2011 Elsevier B.V. All rights reserved.
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    G protein beta 3 subunit gene polymorphism in Turkish hypertensives
    (Aves Yayincilik, 2008) Alioglu, Emin; Ercan, Ertugrul; Tengiz, Istemihan; Yildiz, Ahmet; Tuerk, Ugur Oensel; Saygi, Serkan; Cam, F. Sirri; Berdeli, Afig
    Objective: G protein is one of the most important regulators of intracellular signaling pathways. C825T polymorphism of G protein (33 subunit is associated with increased intracellular signal transduction. The 825T allele has been found associated with a variety of cardiovascular risk factors, including hypertension. The aim of the present study was to investigate the association between the C825T polymorphism of the G protein beta 3 subunit and essential hypertension in Turkish population. Methods: This cross-sectional, case-controlled study included 209 patients with essential hypertension (Patient group) and 82 subjects with normal blood pressure (Control group). The G protein 133 subunit C825T gene polymorphism was determined by polymerase chain reaction. Hypertension was defined according to JNC VII criteria. Statistical analysis was performed using Chi square and unpaired t tests. Logistic regression analysis was used to study association between hypertension and genotypes. Results: We found that the frequencies of the G protein 133 subunit C825T polymorphism in hypertensive and control groups were 17.7%, 59.3%, 23.0% and 32.9%, 48.8%, 18.3%, (CC, CT, TT) respectively (chi(2)=7.963, p=0.019). In the multivariate logistic regression analysis CT genotype had 2.2 (OR=2.262, 95% CI 1.228-4.167, p=0.009), and TT genotype had 2.3 times (OR=2.335, 95% CI 1.089-5.008, p=0.029) greater risk of hypertension compared to CC genotype. Conclusion: It seems that the G protein (33 subunit C825T gene polymorphism is associated with systolic and diastolic blood pressure. Furthermore, the study indicates that the G protein 133 subunit may be a susceptible gene to essential hypertension. (Anadolu Kardiyol Derg 2008; 8: 337-5)