Papers by Mohamed Ibrahim
Ophthalmology, Jan 27, 2018
In recent decades, the treatment paradigm for noninfectious intermediate uveitis, posterior uveit... more In recent decades, the treatment paradigm for noninfectious intermediate uveitis, posterior uveitis, and panuveitis, a group of intraocular inflammatory diseases, has included systemic and local (periocular or intraocular) corticosteroids, biologics, and other steroid-sparing immunomodulatory therapy agents. Recently, an intravitreal formulation of sirolimus, an immunosuppressant that inhibits the mammalian target of rapamycin, a key regulator of cell growth in the immune system, was developed. On the basis of this mechanism and the local method of delivery, it was hypothesized that intravitreal sirolimus can improve ocular inflammation in patients with noninfectious intermediate uveitis, posterior uveitis, and panuveitis, with minimal systemic exposure and systemic adverse events (AEs). This review summarizes the pharmacokinetics, efficacy, and safety results of intravitreal sirolimus from 3 preclinical studies and 4 phase 1-3 clinical studies. Preclinical studies in rabbits showed...
American journal of ophthalmology, Jan 8, 2018
To investigate the natural history of Stargardt disease (STGD1) using fixation location and fixat... more To investigate the natural history of Stargardt disease (STGD1) using fixation location and fixation stability. Multicenter, international, prospective cohort study. Fixation testing was performed using the Nidek MP-1 microperimeter as part of the prospective, multicenter, natural history study on the Progression of Stargardt disease (ProgStar). A total of 238 patients with ABCA4-related STGD1 were enrolled at baseline (bilateral enrollment in 86.6%) and underwent repeat testing at months 6 and 12. Outcome measures included the distance of the preferred retinal locus from the fovea (PRL) and the bivariate contour ellipse area (BCEA). After 12 months of follow-up, the change in the eccentricity of the PRL from the anatomic fovea was -0.0014 degrees (95% confidence interval [CI], -0.27 degrees, 0.27 degrees; P = .99). The deterioration in the stability of fixation as expressed by a larger BCEA encompassing 1 standard deviation of all fixation points was 1.21 degrees squared (deg) (95%...
Investigative ophthalmology & visual science, May 1, 2017
To compare different metrics and acquisition modes of fixation stability as a new visual function... more To compare different metrics and acquisition modes of fixation stability as a new visual function biomarker in a large cohort of patients with ABCA4-related Stargardt disease from the multicenter prospective ProgStar study. Fixation was tested during a separate fixation exam and also dynamically during a sensitivity exam, using fundus-tracking microperimetry (Nidek MP-1). Fixation data were analyzed using the bivariate contour ellipse area (BCEA), the 2/4 degree method, and the Fujii classification. In a total of 235 patients, the mean BCEA was larger when measured during the sensitivity exam (418 eyes; 12.5 vs. 4.6 deg2 during the fixation task in 427 eyes). Correlations between the two tests were generally weak. Fixation stability during the sensitivity test was significantly correlated with visual acuity. Comparing the BCEA values and the corresponding Fujii categories for these eyes revealed ranges of overlap where an eye with one defined BCEA value can fall into each of the thr...
Journal of African Earth Sciences, 2017
Based on seismic interpretation, the time structure map on top of the Abu Roash D Member in the a... more Based on seismic interpretation, the time structure map on top of the Abu Roash D Member in the area of study within the Gindi Basin displays an NE-SW anticline plunging toward the NE intersected by two NE-SW reverse faults. This faulted anticline has been interpreted to have formed by the Late Cretaceous tectonic inversion resulting from the NW movement of the African Plate relative to Laurasia. This anticline creates a distinctive closure which may represent a possible structural hydrocarbon trap in the fractured limestone of the Abu Roash D Member in this area. Through well-logging analysis, the variable cementation exponent "m" has been calculated using the Pickett Plot for the available wells in order to examine the presence of fractures within the entire carbonate Abu Roash D Member. The calculated "m" for Abu Roash D in the two studied wells are 1.56 and 1.34 for SWQ-21 and SWQ-25; respectively which is indicative of the fractured limestone nature. The application of the correct "m" (1.56) instead of 2 (traditional for the intergranular carbonate) for SWQ-21 well has revealed that, the water saturation for the uppermost part of Abu Roash D Member is lower than 50% (normal cut off for carbonate) possessing high porosity and reflecting good reservoir quality. The cross-plot between Archie water saturation (Sw) and neutron porosity (FN) for the uppermost part of this Member follows hyperbola with low BVW (F*Sw) value (0.06) which means that the reservoir is at irreducible state. The visual inspection for the log curve shapes in addition to the application of the presented technique in SWQ-25 well shows that the entire carbonate of Abu Roash D Member is water producing (Sw>50%). These results indicate that the upperpost part of the Abu Roash D Member in well SWQ-21 is fractured limestone and highly promising for hydrocarbon exploration within the Gindi Basin.
Marine Geophysical Research, 2017
JAMA ophthalmology, Jan 25, 2017
New outcome measures for treatment trials for Stargardt disease type 1 (STGD1) and other macular ... more New outcome measures for treatment trials for Stargardt disease type 1 (STGD1) and other macular diseases are needed. Microperimetry allows mapping of light sensitivity of the macula and provides topographic information on visual function beyond visual acuity. To measure and analyze retinal light sensitivity of the macula in STGD1 using fundus-controlled perimetry (microperimetry). This was a multicenter prospective cohort study. A total of 199 patients and 326 eyes with molecularly confirmed (ABCA4) STGD1 underwent testing with the Nidek MP-1 microperimeter as part of the multicenter, prospective Natural History of the Progression of Atrophy Secondary to Stargardt Disease (ProgStar) study. Sensitivity of 68 retinal loci was tested, and the mean sensitivity (MS) was determined; each point was categorized as "normal," "relative," or "deep" scotoma. Mean sensitivity and the number of points with normal sensitivity, relative, or deep scotomas. Mean (SD) pa...
Journal of Applied Business Research (JABR), 2013
The past three decades have witnessed a growing trend in using activity-based costing systems. Ma... more The past three decades have witnessed a growing trend in using activity-based costing systems. Management and accounting research have identified management support as one of the focal points for successful implementation of such systems. However, little research has been done to study managers motivational antecedents to support activity-based costing systems in the Middle East as well as in the Asian countries. It is expected that the level of support differs from one culture to another. This paper addresses this issue in an experimental setting where 129 managers from two different cultures were asked to respond to judgmental decisions to support activity-based costing systems. Two models of the expectancy theory (the force model and the valence model) were used to measure the motivational support for activity-based costing systems. The authors hypothesized that these models provide better explanations than a chance model. The results of the regression analyses support the resear...
Journal of Ophthalmic Inflammation and Infection, 2015
Background The National Eye Institute 39-Question Visual Function Questionnaire (NEI VFQ-39) is a... more Background The National Eye Institute 39-Question Visual Function Questionnaire (NEI VFQ-39) is an indicator of vision-related quality of life (QoL). The NEI VFQ-39 is used to assess the QoL in patients with non-infectious posterior uveitis, intermediate uveitis, or panuveitis, treated with subconjunctival (SCJ) or intravitreal (IVT) sirolimus as an immunomodulatory therapeutic (IMT) agent, delivered subconjunctivally (SCJ) or intravitreally (IVT) (the SAVE Study). Thirty subjects with non-infectious uveitis were randomized (SCJ:IVT, 1:1) for a prospective clinical trial. The 39-Question Visual Function Questionnaire (VFQ-39) was administered at baseline (BL), month 6 (M6), and month 12 (M12) visits. The survey measures self-reported vision health status for patients with chronic eye disease and assesses the effects of visual impairment on both task-oriented visual function and general health domains. In accordance to the NEI-VFQ Manual, each patient’s questionnaire was converted to...
Translational Vision Science & Technology, 2015
Purpose: To determine the efficacy and safety of repeated intravitreal and subconjunctival admini... more Purpose: To determine the efficacy and safety of repeated intravitreal and subconjunctival administrations of sirolimus in patients with noninfectious uveitis at 1 year in the Sirolimus as a Therapeutic Approach UVEitis (SAVE) Study. Methods: Open-label, prospective, and randomized interventional clinical trial in which 30 patients with noninfectious intermediate, posterior, or panuveitis were randomized 1:1 to receive sirolimus 352-lg intravitreal or 1320-lg subconjunctival. Sirolimus was administered at days 0, 60, and 120. At month 6, all subjects were allowed to receive sirolimus at intervals greater than or equal to 2 months and until month 12. Changes in vitreous haze (VH), visual acuity (VA), and retinal thickness at month 12 were compared with baseline. Results: Of patients with active uveitis at baseline (n ¼ 20), 70% showed greater than or equal to 2 steps reduction of VH at month 12 (P , 0.05), 88% (n ¼ 7) of patients with inactive uveitis at baseline showed either no change or reduction of VH to no haze, 36% (n ¼ 10) of all patients (n ¼ 28) gained greater than or equal to one line of VA, 21% (n ¼ 6) lost greater than or equal to 1 line, and 43% (n ¼ 12) showed no change. At the end of 1 year, no statistical differences in efficacy were found between intravitreal and subconjunctival groups. No serious adverse events were determined to be secondary to sirolimus. Conclusions: Repeated subconjunctival/intravitreal injections of sirolimus appear to be tolerated by patients with noninfectious uveitis over 12 months. Results from the index study suggest that sirolimus may provide benefits to patients with uveitis. Both intravitreal and subconjunctival routes demonstrate similar bioactivity/efficacy. The intravitreal route, however, was better tolerated. Translational Relevance: The SAVE Study illustrates for the first time the application of local formulations of sirolimus in non-infectious intermediate, posterior, and panuveitis. Subconjunctival/Intravitreal sirolimus may help to control inflammation while offering better tolerability/safety profiles than systemic therapies, including immunosuppressants and corticosteroids.
Quantitative imaging in medicine and surgery, 2015
To assess oxygen saturation (StO2) in retinal vessels of normal subjects and diabetic patients wi... more To assess oxygen saturation (StO2) in retinal vessels of normal subjects and diabetic patients with and without retinopathy using the modified version of the Flow Oximetry System (FOS) and a novel assessment software. The FOS and novel assessment software were used to determine StO2 levels in arteries and veins located between 1 and 2 mm from the margin of the optic disc and in the macular area. Eighteen normal subjects, 15 diabetics without diabetic retinopathy (DM no DR), and 11 with non-proliferative diabetic retinopathy (NPDR) were included in final analysis. The mean [± standard deviation (SD)] StO2 in retinal arteries was 96.9%±3.8% in normal subjects; 97.4%±3.7% in DM no DR; and 98.4%±2.0% in NPDR. The mean venous StO2 was 57.5%±6.8% in normal subjects; 57.4%±7.5% in DM no DR; and 51.8%±6.8% in NPDR. The mean arterial and venous StO2 across the three groups were not statistically different (P=0.498 and P=0.071, respectively). The arterio-venous differences between the three s...
Journal of Medical Imaging and Health Informatics, 2014
Qatar Foundation Annual Research Forum Volume 2012 Issue 1, 2012
Background and Objectives: There is an escalating interest among patients and consumers in the us... more Background and Objectives: There is an escalating interest among patients and consumers in the use of complementary and alternative medicines (CAM), specifically natural health products, for a variety of illnesses. The public interest in CAM makes it important to explore the attitudes and beliefs of pharmacists involved in selling and dispensing these products. Our objectives were to explore the attitudes of community pharmacists towards CAM and to gauge their opinions about the challenges faced when dispensing CAM during their daily practice. Methods: A qualitative exploratory study was conducted in Doha, Qatar. The Study utilized focus group meetings and a purposive sample of community pharmacists whose pharmacies sell CAM. Recruiting for focus group meetings continued until a point of saturation was reached. The discussions and responses to questions were audio-taped and transcribed verbatim. All recordings were analyzed for recurring themes and subsequently coded and categorized...
North Africa Technical Conference and Exhibition, 2012
Several authors have shown the applicability of modified black oil (MBO) approach for modeling ga... more Several authors have shown the applicability of modified black oil (MBO) approach for modeling gas condensate and volatile oil reservoirs. MBO approach could adequately replace compositional simulation in many applications (including water influx or water injection applications). Changing separator conditions during the history of the simulation run still needs compositional simulation, since PVT properties are calculated for specific separator conditions in black-oil and MBO approaches. Some commercial simulators have treated changes in separator conditions for black-oil applications. However, and to the best of our knowledge, no such treatment exists for the MBO approach. In field operations of volatile oils and gas condensates, however, separator conditions often change because these volatile fluids are usually separated through three and more separation stages, when wellhead pressure allows. We often see that the well stream is usually rerouted to lower pressure separators at la...
BMC pharmacology & toxicology, Jan 14, 2013
This study was designed to assess the safety, tolerability, and efficacy of intravenous infusion ... more This study was designed to assess the safety, tolerability, and efficacy of intravenous infusion of CA4P in patients with neovascular age-related macular degeneration (AMD). Prospective, interventional, dose-escalation clinical trial. Eight patients with neovascular AMD refractory to at least 2 sessions of photodynamic therapy received CA4P at a dose of 27 or 36 mg/m2 as weekly intravenous infusion for 4 consecutive weeks. Safety was monitored by vital signs, ocular and physical examinations, electrocardiogram, routine laboratory tests, and collection of adverse events. Efficacy was assessed using retinal fluorescein angiography, optical coherence tomography, and best corrected visual acuity (BCVA). The most common adverse events were elevated blood pressure (46.7%), QTc prolongation (23.3%), elevated temperature (13.3%), and headache (10%), followed by nausea and eye injection (6.7%). There were no adverse events that were considered severe in intensity and none resulted in discont...
Translational vision science & technology, 2014
To compare the retinal sensitivity measurements obtained with two microperimeters, the Micro-Peri... more To compare the retinal sensitivity measurements obtained with two microperimeters, the Micro-Perimeter 1 (MP-1) and the Optos optical coherence tomography (OCT)/scanning laser ophthalmoscope (SLO) in subjects with and without maculopathies. Forty-five eyes with no known ocular disease and 47 eyes with maculopathies were examined using both microperimeters. A contrast-adjusted scale was applied to resolve the different stimuli and background luminance existing between the two devices. There was a strong ceiling effect with the MP-1 in the healthy group, with 90.1% (1136 of 1260) test points clustered at 20 dB. The mean sensitivity for the corresponding points in the OCT/SLO was 25.8 ± 1.9 dB. A floor effect was also observed with the OCT/SLO in the maculopathy group with 9.7% (128 of 1316) points clustered at 9-dB values. The corresponding mean sensitivity in the MP-1 was 1.7 ± 3.9 dB. A regression equation between the two microperimeters was established in the common 10 to19 dB inte...
Life Sciences, 2005
Nitric oxide (NO) is a potent regulator in the cardiovascular system; it is generated by the nitr... more Nitric oxide (NO) is a potent regulator in the cardiovascular system; it is generated by the nitric oxide synthase (NOS) family of proteins. NO produced in endothelial cells plays a crucial role in vascular functions. The aim of this study was to clarify the effect of diabetes on aortic NO synthesis in a model of genetic hypertension and determine whether captopril modulates this effect. Diabetes was induced in ten weeks old spontaneously hypertensive rats (SHR) by streptozotocin injection. The rats were allocated into 3 groups: control group 1, non-diabetic SHR; group 2, diabetic SHR; group 3, diabetic SHR group receiving captopril at 80 mg/kg in drinking water for 4 weeks. Mean blood pressure (MBP) was measured once a week by tail-cuff method. Aortic NO metabolities (nitrite/nitrate) and endothelial NOS (NOS-3) were assayed by Griess reaction and by immunoblotting and immunohistochemistry, respectively. There was a significant decrease in nitrite/ nitrate (NOx) in aortas of diabetic SHR compared with controls. The decrease of aortic NOx in diabetic SHR was accompanied by a decrease in NOS-3 expression. Captopril treatment reduced MBP without affecting either NOx level or NOS-3 expression in aortas of diabetic SHR. We conclude that STZ-induced diabetes decreased NO in aortas of SHR that may reflect endothelial cell dysfunction; captopril administration decreased MBP
Journal of King Saud …, 2007
This study applied the technology acceptance model (in its original form and in an extended form)... more This study applied the technology acceptance model (in its original form and in an extended form) to the case of the computerized traffic test administered in the Emirate of Sharjah. The authors collected their data using a questionnaire from a sample of 397 applicants who ...
Arabian Journal of Geosciences, 2010
The present work deals with the geology, mineralogy, geochemistry, and origin of the metagabbroic... more The present work deals with the geology, mineralogy, geochemistry, and origin of the metagabbroichosted manganese deposits at Wadi Maliek in the southern Eastern Desert of Egypt. The manganese veins are found in the shear zones and channel ways of the fault planes within the metagabbroic rocks pointing to those hydrothermal solutions carrying manganese and iron load penetrating along these fractures. These faults are striking N 80°E-S 80°W with dipping 65°. These veins vary in thickness from 15 cm up to 125 cm wide; each vein may show difference in thickness from bottom to top. Microscopic examinations, X-ray diffraction, infrared spectral, differential thermal (DTA), thermogravimetric (TGA), and ESEM-EDAX analyses revealed that the manganese minerals consist mainly of pyrolusite, psilomelane, and ramsdellite. Goethite and hematite are the common iron minerals. Petrographically, the manganese deposits can be classified into three ore types based on the predominance of manganese and iron minerals: manganese, manganese-iron, and iron ore types. The geochemistry of Maliek deposits indicated that the total averages of some major oxides in manganese, manganese-iron, and iron ore types are respectively as follows: SiO 2 (15.64%, 11.52%, and 20.58%), MnO (39.9%, 17.81%, and 0.77%), FeO* (7.13%, 33.31%, and 37.08%), CaO (5.89%, 5.82%, and 5.32%), and Na 2 O (1.04%, 1.61%, and 1.53%). With regard to trace elements, the Maliek manganese deposits are rich in Zn, Ba, Pb, Sr, and V. Based on the geological, mineralogical, and geochemical results, the studied manganese deposits are considered to be precipitated from hydrothermal solution.
Advances in Therapy, 2003
The interaction between the renin-angiotensin system and nitric oxide (NO) is undeniable, but its... more The interaction between the renin-angiotensin system and nitric oxide (NO) is undeniable, but its nature is not fully known. This study investigated the contribution of NO to the acute hypotensive effect of captopril in conscious normotensive rats and the effect on blood pressure of dual administration of captopril and the phosphodiesterase-5 inhibitor zaprinast. In two separate experiments, rats were pretreated with the NO inhibitor L-arginine methyl ester (L-NAME) and with the NO enhancer zaprinast. Pretreatment with L-NAME attenuated and pretreatment with zaprinast potentiated the hypotensive effect of captopril. The hypotensive effect of captoril was not associated with a significant change in the plasma level of cyclic guanosine monophosphate (cGMP). These findings suggest that NO contributes to the blood pressure-lowering effect of captopril. The inability of captopril to alter plasma cGMP levels is not consistent with this view, however, and leads to the conclusion that NO contributes to the acute hypotensive effect of captopril, although the mechanism is not fully understood. Zaprinast potentiates the hypotensive effect of captopril, and an adjustment in dose should be considered when this combination is administered.
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Papers by Mohamed Ibrahim