Oral treatment with a zinc complex of acetylsalicylic acid prevents diabetic cardiomyopathy in a rat model of type-2 diabetes: activation of the Akt pathway.

BACKGROUND: Type-2 diabetics have an increased risk of cardiomyopathy, and heart failure is a major cause of death among these patients. Growing evidence indicates that proinflammatory cytokines may induce the development of insulin resistance, and that anti-inflammatory medications may reverse this process. We investigated the effects of the oral administration of zinc and acetylsalicylic acid, in the form of bis(aspirinato)zinc(II)-complex Zn(ASA)2, on different aspects of cardiac damage in Zucker diabetic fatty (ZDF) rats, an experimental model of type-2 diabetic cardiomyopathy. METHODS: Nondiabetic control (ZL) and ZDF rats were treated orally with vehicle or Zn(ASA)2 for 24 days. At the age of 29-30 weeks, the electrical activities, left-ventricular functional parameters and left-ventricular wall thicknesses were assessed. Nitrotyrosine immunohistochemistry, TUNEL-assay, and hematoxylin-eosin staining were performed. The protein expression of the insulin-receptor and PI3K/AKT pathway were quantified by Western blot. RESULTS: Zn(ASA)2-treatment significantly decreased plasma glucose concentration in ZDF rats (39.0 +/- 3.6 vs 49.4 +/- 2.8 mM, P < 0.05) while serum insulin-levels were similar among the groups. Data from cardiac catheterization showed that Zn(ASA)2 normalized the increased left-ventricular diastolic stiffness (end-diastolic pressure-volume relationship: 0.064 +/- 0.008 vs 0.084 +/- 0.014 mmHg/microl; end-diastolic pressure: 6.5 +/- 0.6 vs 7.9 +/- 0.7 mmHg, P < 0.05). Furthermore, ECG-recordings revealed a restoration of prolonged QT-intervals (63 +/- 3 vs 83 +/- 4 ms, P < 0.05) with Zn(ASA)2. Left-ventricular wall thickness, assessed by echocardiography, did not differ among the groups. However histological examination revealed an increase in the cardiomyocytes' transverse cross-section area in ZDF compared to the ZL rats, which was significantly decreased after Zn(ASA)2-treatment. Additionally, a significant fibrotic remodeling was observed in the diabetic rats compared to ZL rats, and Zn(ASA)2-administered ZDF rats showed a similar collagen content as ZL animals. In diabetic hearts Zn(ASA)2 significantly decreased DNA-fragmentation, and nitro-oxidative stress, and up-regulated myocardial phosphorylated-AKT/AKT protein expression. Zn(ASA)2 reduced cardiomyocyte death in a cellular model of oxidative stress. Zn(ASA)2 had no effects on altered myocardial CD36, GLUT-4, and PI3K protein expression. CONCLUSIONS: We demonstrated that treatment of type-2 diabetic rats with Zn(ASA)2 reduced plasma glucose-levels and prevented diabetic cardiomyopathy. The increased myocardial AKT activation could, in part, help to explain the cardioprotective effects of Zn(ASA)2. The oral administration of Zn(ASA)2 may have therapeutic potential, aiming to prevent/treat cardiac complications in type-2 diabetic patients

Barrier height enhancement and stability of the Au/n-InP Schottky barrier diodes oxidized by absorbed water vapor

We have fabricated the Au/n-InP Schottky barrier diodes (SBDs) with and without an intentionally grown interfacial oxide layer. The oxide layer on chemically cleaned indium phosphide (InP) surface has been obtained by exposure to water vapor at 1 ml/min at 200 degrees C before metal evaporation. The chemical composition of the surface oxides grown on the InP is investigated using x-ray photoelectron spectroscopy. Phosphorus is present as In(Po-3)(3), InPO4, P2O5 and elemental R The influence of the oxide on the Schottky barrier formation and contact stability at the InP (100) surface upon subsequent metal deposition has been investigated. The transport properties of the metal-semiconductor contacts have been observed to be significantly affected by the presence of the interfacial oxide layer. Thus, the barrier height has been increased by similar to 140 meV for the Au/n-InP SBD by means of the interfacial oxide grown by use of absorbed water vapor. Furthermore, in order to observe the effect of the aging in the Au/n-InP SBD with and without the interfacial oxide layer, the current-voltage (I-V) measurements have also been repeated 7, 14, 28, 45, 56, and 70 days after fabrication of these diodes. The obtained diode parameters were examined statistically and it was found that the reference and oxidized Au/n-InP SBDs exhibited stable characteristics 14 days after metal deposition. (c) 2005 American Vacuum Society

Ti/p-Si Schottky barrier diodes with interfacial layer prepared by thermal oxidation

We have identically prepared as many as 70 MIS (metal/insulating/semiconductor) Ti/p-Si Schottky barrier diodes (SBDs) with interfacial oxide layer and 70 MS (metal/semiconductor) Ti/p-Si SBDs without interfacial oxide layer for a statistical study. The oxide layer on a chemically cleaned Si surface was obtained by thermal oxidation before metal evaporation. The influence of thermal oxidation on Schottky barrier formation at the Si (10 0) surface upon subsequent metal deposition was investigated. The values of 1.087 and 0.584eV for the mean ideality factor and effective barrier height of the reference (without interfacial layer) MS Ti/p-Si SBDs were obtained from current-voltage (I-P) characteristics, respectively. The values of 1.240 and 0.761 eV for the mean ideality factor and effective barrier height of MIS Ti/p-Si SBDs with the thin oxide layer, respectively, were obtained from I-V characteristics. The transport properties of the metal-semiconductor contacts were observed to be drastically affected by the presence of the interfacial oxide layer. Thus, the barrier height was increased by 177 meV for Ti/p-Si by means of the thermal oxide. Furthermore, we have calculated a mean tunneling barrier height of chi = 0.31 eV for the MIS Ti/p-Si SBDs with interfacial oxide layer. (c) 2005 Elsevier B.V. All rights reserved

The barrier-height inhomogeneity in identically prepared H-terminated Ti/p-Si Schottky barrier diodes

We have identically prepared as many as 60 Ti/p-Si (100) Schottky barrier diodes (SBDs) with a doping density of about 10(15) cm(-3). The Si (100)-H surfaces were obtained by wet chemical etching in diluted hydrofloric acid. We have made a statistical study related to the experimental barrier heights (BHs) and ideality factors of the diodes, and we have looked at linear relationship between BHs and ideality factors. The BHs obtained from the current-voltage (I-V) characteristics varied from 0.556 to 0.617 eV, and the ideality factor varied from 1.019 to 1.196. The experimental BH and ideality factor distributions obtained from the I-V characteristics were fitted by a Gaussian function, and their mean values were found to be 0.577 +/- 0.013 eV and 1.098 +/- 0.044, respectively. Furthermore, the homogeneous BH value of approximately 0.602 eV for the device was obtained from the linear relationship between experimental effective BHs and ideality factors

Anatomical analysis of azygos vein system in human cadavers

The azygos system veins vary greatly in their mode of origin, course, tributaries, anastomoses and termination. Therefore, we aimed to investigate the types of azygos system in this study. Our research was made in Anatomy departments on 48 conserved cadavers aging between 27-70 years, of which 35 were males and 13 females. In the research, the diameters and levels of the azygos vein, the hemiazygos vein, the accessory hemiazygos vein and the superior intercostal vein were investigated. The subjects were classified in Anson's system with a basis of vertical and horizontal connections in the azygos venous system the classification included primitive or embryological types, transient type, unicolon type as three basic types and their eleven subgroups. According to this classification (amongst 48 cadavers), one (2.1%) of our subjects was found to be Type I, 44 (91.7%) of them were found to be Type II, and one (2.1%) was found to be Type III. These values were similar to those in the literature, however two (4.2%) subjects did not fit in any otherwise defined groups and were named as atypic group. It is very important to identify the variations of the azygos system in the computed tomography and magnetic resonance imaging of mediastinum. The abnormal azygos venous system may easily be confused with aneurysm, lymphadenopathy and other abnormalities like tumor. It is important to keep these kinds of variations in mind while performing the mediastinal operations or surgery of large vessels

Determination of the characteristic parameters of Sn/n-GaAs/Al-Ge Schottky diodes by a barrier height inhomogeneity model

A study on parameters of the Sn/n-GaAs Schottky barrier diode (SBD) fabricated on an n-type GaAs substrate has been made. The Sn/n-GaAs SBD has shown a nearly ideal behaviour with ideality factor and barrier height (BH) values of 1.081 and 0.642 eV, respectively, from the experimental forward-bias current-voltage (I-V) characteristics. A BH value of 0.724 eV has been obtained from the experimental reverse-bias capacitance-voltage (C-V) characteristics. An accurate theoretical modelling of the effect of the presence of inhomogeneities on the electron transport across the metal-semiconductor interface has been applied. This model attempts to explain abnormal experimental results obtained on 'real' Schottky diodes. Our results clearly demonstrate that the electron transport at the metal-semiconductor interface is significantly affected by low-barrier regions (patches). When the experimental data are described by the thermionic emission theory of inhomogeneous Schottky contacts, it has been concluded that both the experimental forward and reverse I-V characteristics and the difference between the values of the experimental I-V and C-V SBHs should be considered. An experimental BH difference of Delta = 0.082 V has been obtained for the Sn/n-GaAs SBD that is less than the critical value; therefore, it has been seen that the potential in front of the patch is not pinched off

Series resistance calculation for the metal-insulator-semiconductor Schottky barrier diodes

An accurate way of determining the series resistance R(s) of Schottky Barrier Diodes (SBDs) with and without the interfacial oxide layer using forward current-voltage (I-V) characteristics is discussed both theoretically and experimentally by taking into account the applied voltage drop across the interfacial layer V-i. For the experimental discussion, the forward bias I-V characteristics of the SBDs with and without the oxide layer fabricated by LEC (the Liquid-Encapsulated Czochralski) GaAs were performed. The SBD without the oxide layer was fabricated to confirm a novel calculation method. For the theoretical discussion, an expression of V-i was obtained by considering effects of the layer thickness and the interface state density parameters on forward bias I-V of the SBDs. The Value R(s) of the SBD with interfacial oxide layer was seen to be larger than that of the SBD without the interfacial oxide layer due to contribution of this layer to the series resistance. According to the obtained theoretical formula, the value of V-i for the SBD with the oxide layer was calculated and it was subtracted from the applied voltage values V and then the value of R(s) was recalculated. Thus, it has been shown that this new value of R(s) is in much closer agreement with that determined for the SBD without the oxide layer as predicted. Furthermore, the curves of the interface states energy distribution of each sample are determined. It was concluded that the shape of the density distribution curve and order of magnitude of the density of the interface states in the considered energy range are in close agreement with those obtained by others for Au/n-GaAs Schottky diodes by Schottky capacitance spectroscopy

Effect of series resistance on the forward current-voltage characteristics of Schottky diodes in the presence of interfacial layer

In order to make an accurate determination of Schottky diode parameters such as the ideality factor, the barrier height and the series resistance [using forward current-voltage (I-V) characteristics in the presence of an interfacial layer], a novel calculation method has been developed by taking into account the applied voltage drop across the interfacial layer (V-i). The parameters obtained by accounting for the voltage drop V,have been compared with those obtained without considering the above voltage drop. To examine the consistency of this approach, the comparison has been made by means of Schottky diodes fabricated on a n-type semiconductor substrate with different bulk thickness. It is shown that the voltage drop across the interfacial layer will increase the ideality factor and the voltage dependence of the I-V characteristics. In addition, it is shown that the series resistance value increases as the semiconductor bulk thickness has been increased

INTERPRETING THE NONIDEAL REVERSE BIAS C-V CHARACTERISTICS AND IMPORTANCE OF THE DEPENDENCE OF SCHOTTKY-BARRIER HEIGHT ON APPLIED VOLTAGE

WOS: A1995QF66000007This work presents an attempt related to the charging behaviour of interface states to the nonideal forward bias current-voltage (I-V) and the reverse bias capacitance-voltage (C-V) characteristics of A1-nSi Schottky barrier diodes. The diode showed nonideal I-V behaviour with an ideality factor of 1.50 and was thought to have a metal-interface layer-semiconductor configuration. Considering that the interface states localized at the interfacial layer-semiconductor interface are in equilibrium with the semiconductor, the energy distribution of the interface states was exactly determined from the forward bias I-V characteristics by taking into account the bias dependence of the effective barrier height, Phi(e). The determination of the intercept voltage and interface state density was made by means of a simple interface charge model which has been developed in detail. The I-V characteristics were used for determining the voltage dependence of the barrier height. Although the change in barrier height with applied bias is small, it is important for exactly determining the shape of the interface state density distribution curve. At a frequency of 500 kHz, the nonlinear reverse bias C-2-V plot with the curvature concave downward has been only thought of to be due to the contribution of the capacitance of the interface state charges. It is concluded that the nonlinear nature of C-2-V plots in the frequency range 50-200 kHz has been caused by the interface state charges as well as inversion layer and inversion layer charges. It has been understood by means of the interface state charge model that the C-2-V plots cannot only be interpreted in terms of the contribution of the interface state charges to the device capacitance