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Search Results: 1 - 10 of 26821 matches for " Ahmed Al-Sabi "
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Marine Toxins That Target Voltage-gated Sodium Channels
Ahmed Al-Sabi,Jeff McArthur,Vitaly Ostroumov,Robert J. French
Marine Drugs , 2006, DOI: 10.3390/md403157
Abstract: Eukaryotic, voltage-gated sodium (NaV) channels are large membrane proteins which underlie generation and propagation of rapid electrical signals in nerve, muscle and heart. Nine different NaV receptor sites, for natural ligands and/or drugs, have been identified, based on functional analyses and site-directed mutagenesis. In the marine ecosystem, numerous toxins have evolved to disrupt NaV channel function, either by inhibition of current flow through the channels, or by modifying the activation and inactivation gating processes by which the channels open and close. These toxins function in their native environment as offensive or defensive weapons in prey capture or deterrence of predators. In composition, they range from organic molecules of varying size and complexity to peptides consisting of ~10-70 amino acids. We review the variety of known NaV-targeted marine toxins, outlining, where known, their sites of interaction with the channel protein and their functional effects. In a number of cases, these natural ligands have the potential applications as drugs in clinical settings, or as models for drug development.
Disruption of Myelin Leads to Ectopic Expression of KV1.1 Channels with Abnormal Conductivity of Optic Nerve Axons in a Cuprizone-Induced Model of Demyelination
Bandita Bagchi, Ahmed Al-Sabi, Seshu Kaza, Dimitri Scholz, Valerie B. O'Leary, J. Oliver Dolly, Saak V. Ovsepian
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0087736
Abstract: The molecular determinants of abnormal propagation of action potentials along axons and ectopic conductance in demyelinating diseases of the central nervous system, like multiple sclerosis (MS), are poorly defined. Widespread interruption of myelin occurs in several mouse models of demyelination, rendering them useful for research. Herein, considerable myelin loss is shown in the optic nerves of cuprizone-treated demyelinating mice. Immuno-fluorescence confocal analysis of the expression and distribution of voltage-activated K+ channels (KV1.1 and 1.2 α subunits) revealed their spread from typical juxta-paranodal (JXP) sites to nodes in demyelinated axons, albeit with a disproportionate increase in the level of KV1.1 subunit. Functionally, in contrast to monophasic compound action potentials (CAPs) recorded in controls, responses derived from optic nerves of cuprizone-treated mice displayed initial synchronous waveform followed by a dispersed component. Partial restoration of CAPs by broad spectrum (4-aminopyridine) or KV1.1-subunit selective (dendrotoxin K) blockers of K+ currents suggest enhanced KV1.1-mediated conductance in the demyelinated optic nerve. Biophysical profiling of K+ currents mediated by recombinant channels comprised of different KV1.1 and 1.2 stoichiometries revealed that the enrichment of KV1 channels KV1.1 subunit endows a decrease in the voltage threshold and accelerates the activation kinetics. Together with the morphometric data, these findings provide important clues to a molecular basis for temporal dispersion of CAPs and reduced excitability of demyelinated optic nerves, which could be of potential relevance to the patho-physiology of MS and related disorders.
Comparison of the Bayesian Methods on Interval-Censored Data for Weibull Distribution  [PDF]
Al Omari Mohammed Ahmed
Open Journal of Statistics (OJS) , 2014, DOI: 10.4236/ojs.2014.48053
Abstract: This study considers the estimation of Maximum Likelihood Estimator and the Bayesian Estimator of the Weibull distribution with interval-censored data. The Bayesian estimation can’t be used to solve the parameters analytically and therefore Markov Chain Monte Carlo is used, where the full conditional distribution for the scale and shape parameters are obtained via Metropolis-Hastings algorithm. Also Lindley’s approximation is used. The two methods are compared to maximum likelihood counterparts and the comparisons are made with respect to the mean square error (MSE) to determine the best for estimating of the scale and shape parameters.
The Environmental Impacts of Kabd Landfill on the Soil and Groundwater in Kuwait: A Case Study  [PDF]
Ahmed R. Al Rashed
International Journal of Geosciences (IJG) , 2018, DOI: 10.4236/ijg.2018.95016
Abstract: The environmental impacts of the Kabd Landfill on the soil and groundwater in Kuwait were evaluated. Physical and chemical analyses were carried out on thirty pairs of surface, subsurface soil and five groundwater samples. The groundwater samples are collected from boreholes nearby and downstream of the landfill while the soil samples collected along six profiles. The groundwater samples were geochemically analyzed to determine the total dissolved solids, cations, anions and heavy metals, particularly Iron (Fe), Copper (Cu), zinc (Zn), Cadmium (Cd), Nickel (Ni), Chromium (Cr) and Aluminum (Al), Lithium (Li), Boron (B), Fluoride (F) and Vanadium (V). The soil samples were geochemically analyzed to determine concentration of Cadmium (Cd), Lead (Pb), Nickel (Ni), Iron (Fe), Aluminum (Al) and organics. The results show that the soil and groundwater are contaminated with high TDS, Na, Ca, Mg, Cl, SO4 and heavy metals, especially Ni, Cd, Cu, Al, V and F. The heavy metal concentrations in both the soil and groundwater samples are compared to the World Health Organization (WHO) standard permissible limits. The results revealed that the Zn, Li, B and Fe metals are below the WHO limits for consumption. The soil lithology, natures of dumping, the depth of quarry and the depth to the groundwater level play roles in leachate generation and groundwater contaminations. Such leachate may be originated from the capillary fringe water, moisture content and rising water table, due to its close level at the bottom of the waste disposal site. The organic strength of the soil was reduced due to waste decomposition and continuous gas
Hyperuricemia in Patients with Chronic Renal Failure in the General Hospital of National Reference of N’Djamena (Chad)  [PDF]
Guillaume Mahamat Abderraman, Ibrahim Hamat, Zeinabou Maiga Moussa Tondi, Ahmed Tall Lemrabott, Maria Faye, Cisse Mouhamadou Moustapha, Kossi Akomola Sabi, Ka Elhaj Fary Ka, Niang Abdou, Diouf Boucar
Open Journal of Nephrology (OJNeph) , 2017, DOI: 10.4236/ojneph.2017.71002
Abstract: Introduction: Hyperuricemia is defined as a level of serum uric acid greater than or equal to 70 mg/l (420 μmol/l) in men and 60 mg/l (360 μmol/l) in women. Several studies have shown that it is a risk factor or a factor of progression of chronic kidney disease. Recent experimental and epidemiological data correlate the association of hyperuricemia with chronic kidney disease (CKD), arterial hypertension and cardiovascular diseases, thus raising the question of the usefulness of therapeutics in the prevention of renal diseases. The objective of this study is to seek a link between chronic kidney disease and hyperuricemia. Materials and Methods: This is a descriptive and analytical study conducted at hemodialysis unit and cardiology service of General Hospital of National reference of N’Djamena (Chad) from 1th January to 1th October 2013 (10 months). We included all chronic kidney disease patients hospitalized in hemodialysis unit and cardiology service who presented associated hyperuricemia. Results: There were 712 CKD patients who were hospitalized. Among them, there were 108 patients who were included in the study and who had hyperuricemia as a prevalence of 15.20%. The average age of patients was 35.5 years and the sex ratio was 3/1. The age group between 40 to 60 years represented 54.6%. There were 41.7% of traders. Hypertensive patients accounted for 49.1%; association of diabetes and hypertension was noted in 12.90%. Renal insufficiency was moderate in 43.5% of patients. Hyperuricemia was present in more than 90% of patients. Profession, age, hematuria, proteinuria and hypertension were statistically positively related to hyperuricemia. Treatment consisted of prescribing allopurinol in 84% of patients. In more than 11% of patients the progression was unfavorable. Conclusion: The implication of hyperuricemia in chronic kidney disease has been proved in several recent studies. However, randomized studies at very long scales have to be carried out to conclude from its real impact on the prevention and treatment of chronic kidney disease.
Validation of Chaviaro Poulos and Hansen Stall Delay Model in the Case of Horizontal Axis Wind Turbine Operating in Yaw Conditions  [PDF]
Abdelfattah Bouatem, Ahmed Al Mers
Energy and Power Engineering (EPE) , 2013, DOI: 10.4236/epe.2013.51003
Abstract:

Operating in natural wind field, the horizontal axis wind turbines are subject to cyclical variation of aerodynamic loads. This cyclical loads fluctuation is a result of two aerodynamic phenomenon: the first one is the advancing and retreating blade effect; the second one is related to the cyclical variation of induced velocity at the rotor plane. In these operating conditions, the correct prediction of this load variation is necessary to predict some important parameters linked to the fatigue and stability of free yawing turbines. The main objective of the present study is the evaluation of the azimuthal variation of normal force at different radial positions. To model the problem, the blade element momentum theory is used and wind turbine is supposed operate in yaw conditions. The aerodynamic coefficients are corrected using Chaviaropoulos and Hansen model to take into account the phenomenon of stall delay. A computer code was developed to obtain the numerical values and results are compared with measurements performed in the NASA Ames wind tunnel.

Simultaneous Bilateral Spontaneous Pneumothorax: Report of 6 Adult Patients  [PDF]
Ahmed I. Al-Azzawi
World Journal of Cardiovascular Surgery (WJCS) , 2015, DOI: 10.4236/wjcs.2015.52004
Abstract: Background: Spontaneous pneumothorax (SP) refers to the spontaneous presence of air in the pleural sac(s) without iatrogenic or traumatic factors. The simultaneous bilateral SP (SBSP) is rare yet serious clinical condition which may pose a significant threat to patient’s life. Herein, 6 patients with SBSP managed in Sulaimaniyah Teaching Hospital (STH) over 6-year period (2006-2011) are reported with literature review. Methodology: A prospective clinical study. The diagnosis was made on clinical and radiographic grounds. The initial therapy was a bilateral tube thoracostomy (BTT) followed by chemical pleurodesis. Thoracotomy for excision of subpleural blebs or bullae and pleurectomy was performed for prolonged air leak (lasting >14 days). Results: There were 5 males (83.33%) and 1 female (16.67%) with a mean age of 34.8 years ranging between 20 and 50. All patients had presented with dyspnea and chest pain and were smokers. Three patients (50%) had primary (PSP) whereas the remaining had secondary (SSP) (chronic obstructive pulmonary disease—COPD, n = 2 and pneumonia, n = 1). None of the patients had recurrence. Unilateral thoracotomy was necessary in 5 patients (SSP, n = 3 and PSP, n = 2). Prolonged air leak was observed once postoperatively (16.7%) while mortality was nil. Conclusions: Prompt recognition of this rare yet potentially serious condition is crucial. The clinical diagnosis is straightforward with plain chest radiography being the most helpful workup. The initial therapy is via BTT followed by pleurodesis. Surgery is necessary for prolonged air leak and failure of the lung to expand.
Seismic Evaluation of Reinforced Concrete Frames in the Harsh Environment Using Pushover Analysis  [PDF]
Mohamed Sobaih, Ahmed Al Ghazali
Open Journal of Civil Engineering (OJCE) , 2016, DOI: 10.4236/ojce.2016.64055
Abstract: The main objective of this paper is to evaluate the seismic response of buildings of typical reinforced concrete frames when concrete starts to deteriorate gradually and to make a comparison between the base shear and the displacement at different stages of earthquake loading. Typical 5, 15, 20 and 30-storey reinforced concrete frames have been designed for seismicity according to the recently adopted seismic code in Abu Dhabi, ACI 318-08/IBC 2009 code. A pushover analysis has been performed to these four buildings by using SAP 2000. Twenty-four models have been created (6 models for each building) by decreasing the concrete strength gradually from 4000 psi (281 kg/cm2) to 1500 psi (105 kg/cm2). This is to simulate the effect of harsh environment on the strength of concrete in existing buildings.
The Legal System for Credit Cards in Jordan  [PDF]
Ahmed Adnan Al-Nuemat
Beijing Law Review (BLR) , 2017, DOI: 10.4236/blr.2017.82010
Abstract: As a widely used banking service and application, credit cards have gained popularity in the last few years. They have broadened in techniques, impressions on clients and consumer transactions. Owing to the fact that masses are utilizing this facility, credit cards have become more popular, especially in Jordan. The lawmakers of the country have not yet updated the legal system according to the ongoing advancements through special laws. Such an update would pave the way for legal protection. This is an ongoing process, and people are currently experiencing legal dilemmas owing to the unlawful use of credit cards.
Extraction of Aspirated Headscarf Pins with Fiberoptic Bronchoscopy  [PDF]
Ahmed I. Al-Azzawi
World Journal of Cardiovascular Surgery (WJCS) , 2017, DOI: 10.4236/wjcs.2017.712016
Abstract: Background: Foreign body aspiration is a common yet preventable health problem. Headscarf pin aspiration is a unique example of aspirated foreign bodies in young Muslim women usually removed using the rigid bronchoscope. However, the flexible bronchoscope is increasingly used for this purpose. This prospective study was conducted in Sulaimaniyah Teaching Hospital, Sulaimaniyah, Iraq and aimed to evaluate the usefulness of fiberoptic bronchoscope for removal of aspirated headscarf pins in view of the relevant literature. Methodology: Fifty female patients with headscarf pin aspiration were managed by fiberoptic bronchoscopy over an 8-year period (January 2008 to December 2015). The procedure was performed under local anesthesia and conscious sedation through the mouth. Results: The age ranged from 10 to 45 years with a mean of 27.5. All patients had cough, five had unilateral wheeze (10%) while haemoptysis occurred twice (4%). Fiberoptic bronchoscopy succeeded in 45 cases (90%). Rigid bronchoscopy under general anesthesia was necessary in (n = 4, 8%) while one patient (2%) required thoracotomy. Conclusion: Fiberoptic bronchoscopy is safe and effective in removal of aspirated headscarf pins and should be tried first.
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