Role of Leukotriene in Gastric Ulcer Induced by Acetyl Salicylic Acid in Male Rabbits : Gastroprotection by Montelukast

Gastric mucosal damage is a common disorder of the gastrointestinal system. Non- steroidal anti-inflammatory drugs (NSAID) are known to be aggressive agents for gastric ulcer development. Leukotrienes  play an important role in gastric mucosal damage induced by NSAIDs. Montelukast , a selective reversible Cysteinyl leukotriene receptor 1 antagonist, was reported to have beneficial effects in management of experimental gastric mucosal ulceration. This study designed to evaluate  the role of leukotriene against acetyl salicylic acid-induced gastric mucosal damage and to evaluate the gastroprotective activity of montelukast . Thirty local domestic male rabbits had been used in this study , divided into five groups as follows: normal control group, acetylsalicylic acid ( ASA) treated group, Omeprazole pretreatment group, montelukast pretreatment group, montelukast alone  treatment group. At the end of the experiment, the stomach of rabbit  is removed to prepare the tissue homogenate .  The results revealed that after administration of ASA significantly increase the mean ulcer index along with the LTD4 concentration, LTB4 concentration . But in presence of  montelukast  there is a significant decreased in the mean ulcer index along with  LTD4 concentration, LTB4 concentration .  These results suggest that the leukotrienes play an important role in  acetyl salicylic acid induced gastric ulcerations and gastroprotective activity of montelukast can be attributed to decreased activity of leukotrienes in gastric mucosa . Keywords :  Gastric ulcer , H.pylori , Non-steroidal anti-inflammatory drugs , montelukas

Solving Nonstiff Higher-Order Ordinary Differential Equations Using 2-Point Block Method Directly

We describe the development of a 2-point block backward difference method (2PBBD) for solving system of nonstiff higher-order ordinary differential equations (ODEs) directly. The method computes the approximate solutions at two points simultaneously within an equidistant block. The integration coefficients that are used in the method are obtained only once at the start of the integration. Numerical results are presented to compare the performances of the method developed with 1-point backward difference method (1PBD) and 2-point block divided difference method (2PBDD). The result indicated that, for finer step sizes, this method performs better than the other two methods, that is, 1PBD and 2PBDD

Thermal characteristics and performance of Ag-water nanofluid: Application to natural circulation loops

The goal of this study is to investigate the thermal conductivity, viscosity and thermal performance in a single-phase natural circulation mini loop of Ag-water nanofluid which can be a potential working fluid for natural convective flat-plate solar collectors. The silver-water nanofluid with 5 wt% concentration, which contains also polyvinylpyrrolidone (PVP) with 1.25 wt%, was purchased. Then, the sample was diluted with de-ionized water to four different concentrations of 0.25, 0.5, 0.75 and 1 wt%. Thermal conductivity and viscosity were measured by 3 omega method and Brookfield rheometer, respectively. An effectiveness factor was used to define the thermal performance of Ag-water nanofluids for different inclination angles and heating powers. The results showed that nanofluid samples are thermally less conductive than the literature, at ambient temperature (23 degrees C). The viscosity of nanofluid decreases significantly with increasing temperature and increases with increasing concentration. Our measurements appear to be more compatible with PVP solution results available in the literature. Effectiveness is enhanced up to 11% with 1 wt% concentrated nanofluid compared to de-ionized water and the effectiveness of the mini loop indicates an enhancement with increase in inclination angle and particle concentration at whole applied power. According to obtained results, it is concluded that Ag-water nanofluid has a promising potential to be used in natural convective flat-plate solar collector. (C) 2016 Elsevier Ltd. All rights reserved