Mohamed Gad
Desert Research Institute, Hydrology, Faculty Member
- I'm Prof Dr in Hydrology.I worked as Regional Hydrogeological Consultant in World Bank Project (SBWMP). I work in Des... moreI'm Prof Dr in Hydrology.I worked as Regional Hydrogeological Consultant in World Bank Project (SBWMP). I work in Desert Research Center in Egypt. I like work in scientific research.I cooperate with my colleagues to publish my works in modern scientific issues related to environmental and sociology-economic problems(I'm Prof Dr in Hydrology.I worked as Regional Hydrogeological Consultant in World Bank Project (SBWMP). I work in Desert Research Center in Egypt. I like work in scientific research.I cooperate with my colleagues to publish my works in modern scientific issues related to environmental and sociology-economic problems)edit
Research Interests:
ABSTRACT
ABSTRACT
Research Interests:
Reasonable utilization of land and water in transboundary aquifer systems requires consideration of the social and ecological dimensions of groundwater use. This paper discusses the experience of local institutions in monitoring and... more
Reasonable utilization of land and water in transboundary aquifer systems requires consideration of the social and ecological dimensions of groundwater use. This paper discusses the experience of local institutions in monitoring and managing the changing groundwater conditions and utilization at the terminal outlets to two major North African transboundary aquifer systems, the Nubian Sandstone Aquifer System (NSAS) and the North West Sandstone Aquifer System (NWSAS). Results from a multidisciplinary analysis of national research archives, remote sensing, interviews with decision-makers and direct surveys of cultivators in selected oases in both regions are used to examine the impacts of accelerated groundwater extraction from these systems during land reclamation and cultivation for both domestic and international agricultural export markets over the past two decades. Opportunities are identified for international initiatives to improve the management of the aquifer systems by encou...
Research Interests:
The cellular distribution of enzymes that esterify retinol and hydrolyze retinyl esters (RE) was studied in liver of vitamin A-sufficient,-deficient, and deficient rats treated with retinoic acid or N-(4-hydroxyphenyl)- retinamide. Livers... more
The cellular distribution of enzymes that esterify retinol and hydrolyze retinyl esters (RE) was studied in liver of vitamin A-sufficient,-deficient, and deficient rats treated with retinoic acid or N-(4-hydroxyphenyl)- retinamide. Livers were perfused and cell fractions enriched in hepatocytes, and nonparenchymal cells were obtained for assays of RE and enzyme activity. The specific activity of lecithin:retinol acyltransferase (LRAT) was approximately
Research Interests:
Research Interests:
We recently reported the presence of a neutral, bile salt-independent retinyl ester hydrolase (REH) activity in rat liver microsomes and showed that it was distinct from the previously studied bile salt-dependent REH and from nonspecific... more
We recently reported the presence of a neutral, bile salt-independent retinyl ester hydrolase (REH) activity in rat liver microsomes and showed that it was distinct from the previously studied bile salt-dependent REH and from nonspecific carboxylesterases (Harrison, E. H., and M. Z. Gad. 1989. J. Biol. Chem. 264: 17142-17147). We have now further characterized the hydrolysis of retinyl esters by liver microsomes and have compared the observed activities with those catalyzing the hydrolysis of cholesteryl esters. Microsomes and microsomal subfractions enriched in plasma membranes and endosomes catalyze the hydrolysis of retinyl esters at both neutral and acid pH. The acid and neutral REH enzyme activities can be distinguished from one another on the basis of selective inhibition by metal ions and by irreversible, active site-directed serine esterase inhibitors. The same preparations also catalyze the hydrolysis of cholesteryl esters at both acid and neutral pH. However, the enzyme(s)...
Research Interests:
Nitric oxide (NO) appears to play a critical role in modulating gastric mucosal defense. Administration of NO donors has been reported to protect the gastrointestinal mucosa against damage induced by several irritants. However, the... more
Nitric oxide (NO) appears to play a critical role in modulating gastric mucosal defense. Administration of NO donors has been reported to protect the gastrointestinal mucosa against damage induced by several irritants. However, the possible role of NO in healing existing ulcers must be clarified further. Therefore, the present study was designed to assess the effect of modulation of NO on the healing of an indomethacin-induced peptic ulcer using a NO precursor, L-arginine, and a competitive inhibitor of NO synthase, L-NAME. Results of administering L-arginine were compared to those using nitroglycerin (NTG), an NO donor. Rats were injected with a single oral dose of indomethacin (30 mg/kg) and then treated with L-arginine (200 mg/kg, i.p.), NTG (1 mg/kg, i.p.) or L-NAME (15 mg/kg, i.p.) once daily for 7 d starting 4 h after the indomethacin injection. Gross lesion examination and histological assessment were done. NO, prostaglandin (PGE2), and mucin content in gastric tissue were de...
Research Interests:
The major goal of this study was to examine the ability of several antioxidants namely, vitamin E, beta-carotene and N-acetylcysteine, to protect the brain from oxidative stress induced by lipopolysaccharide (LPS, endotoxin). LPS, a... more
The major goal of this study was to examine the ability of several antioxidants namely, vitamin E, beta-carotene and N-acetylcysteine, to protect the brain from oxidative stress induced by lipopolysaccharide (LPS, endotoxin). LPS, a component of the bacterial wall of gram-negative bacteria, has been recognized as one of the most potent bacterial products in the induction of host inflammatory responses and tissue injury and was used in this study to mimic infections. LPS injection resulted in a significant increase in the stress indices, plasma corticosterone and glucose concentration, a significant alteration of the brain oxidative status observed as elevation of the level of malondialdehyde (MDA, index of lipid peroxidation) and reduction of reduced glutathione (GSH), and a disturbance in the brain energy metabolism presented as a reduction in the ATP/ADP ratio and an increase in the mitochondrial/cytosolic hexokinase ratio. However, the activities of brain superoxide dismutase and...
Research Interests: Phospholipids, Oxidative Stress, Antioxidants, Brain, Blood Glucose, and 16 moreCholesterol, Animals, Corticosterone, Male, Glutathione, Vitamin E, Anti-inflammatory agents, Superoxide Dismutase, Lipopolysaccharides, Rats, Beta Carotene, Wistar Rats, N-Acetylcysteine, Malondialdehyde, Biochemistry and cell biology, and Adenosine Triphosphate
The cellular distribution of enzymes that esterify retinol and hydrolyze retinyl esters (RE) was studied in liver of vitamin A-sufficient, -deficient, and deficient rats treated with retinoic acid or N-(4-hydroxyphenyl)-retinamide. Livers... more
The cellular distribution of enzymes that esterify retinol and hydrolyze retinyl esters (RE) was studied in liver of vitamin A-sufficient, -deficient, and deficient rats treated with retinoic acid or N-(4-hydroxyphenyl)-retinamide. Livers were perfused and cell fractions enriched in hepatocytes, and nonparenchymal cells were obtained for assays of RE and enzyme activity. The specific activity of lecithin:retinol acyltransferase (LRAT) was approximately 10-fold greater in the nonparenchymal cell than the hepatocyte fraction from both vitamin A-sufficient and retinoid-treated rats. Total RE mass, newly synthesized [3H]RE and LRAT activity were positively correlated in liver and isolated cells of both normal (P < 0.0001) and retinoid-treated rats (P < 0.0002). In nonparenchymal cells, these three constituents were nearly equally enriched as evaluated by their relative specific activity values (RSA, defined as the percentage of recovered activity divided by the percentage of recov...
Research Interests:
Serum lactate dehydrogenase (LDH) isoenzyme and amino acid (a.a) patterns were evaluated in comparison to several other biochemical parameters for liver and renal function with the objective of clarifying the differential diagnosis of... more
Serum lactate dehydrogenase (LDH) isoenzyme and amino acid (a.a) patterns were evaluated in comparison to several other biochemical parameters for liver and renal function with the objective of clarifying the differential diagnosis of hepatic disorders and predicting the outcome of schistosomal infection in Egyptian patients. Patients examined included those with complicated hepatic disorders and others with different stages of schistosomal infestation, hepatoma or bladder cancer, in addition to a normal control group. Several biochemical parameters appeared to be useful in establishing consistent differences or similarities between the studied groups. Examples are; elevated serum AST/ALT ratio and methionine content in chronic schistosomiasis, elevated serum urea/creatinine ratio and leucine content in all schistosomal patients and extremely high levels of N-acetyl-beta-D-glucosaminidase (NAG) in the urine of non-schistosomal bladder cancer patients. In addition, characteristic LDH...
Research Interests:
Three antischistosomal drugs, praziquantel (CAS 55268-74-1, EMBAY 8440, Prz), oxamniquine (CAS 21738-42-1, Oxa) and oltipraz (CAS 64224-21-1, Olt) were examined for their ability to reverse the disturbances in carbohydrate metabolism... more
Three antischistosomal drugs, praziquantel (CAS 55268-74-1, EMBAY 8440, Prz), oxamniquine (CAS 21738-42-1, Oxa) and oltipraz (CAS 64224-21-1, Olt) were examined for their ability to reverse the disturbances in carbohydrate metabolism induced by Schistosoma mansoni (S. mansoni) infection. The infected mice were screened every 2 weeks for 16 weeks for their body and liver weights in addition to assessment of the activities of liver pyruvate kinase (PK), phosphofructokinase (PFK) (glycolysis), citrate synthase (CS) (Krebs' cycle) glycogen phosphorylase (GP) (glycogenolysis), glucose-6-phosphate dehydrogenase (G6PDH) and 6-phosphogluconate dehydrogenase (6PGDH) (hexose monophosphate shunt). Results of the study showed that infection with S. mansoni caused the following changes in mice livers: 1. significant increase in liver weights from the 6th week of infection, which coincided with schistosomal egg deposition, whereas body weights were reduced, 2. remarkable increase in the activ...
Research Interests: Glucose, Liver, Mice, Female, Animals, and 5 moreMale, Glycolysis, Body Weight, Praziquantel, and Pentose Phosphate Pathway
Radiation inactivation by high energy electrons, a method for determining the size of a protein without prior purification, was used to study the acid and neutral cholesteryl ester hydrolase (CEH) activities of rat liver microsomes. The... more
Radiation inactivation by high energy electrons, a method for determining the size of a protein without prior purification, was used to study the acid and neutral cholesteryl ester hydrolase (CEH) activities of rat liver microsomes. The same preparations were also assayed for the microsomal, "nonspecific" carboxylesterases using o-nitrophenyl acetate as substrate. Non-specific esterase activity surviving radiation could be fit to a single exponential function, the slope of which yielded a target size of 47 +/- 5 kDa (mean +/- S.D., n = 7). Surviving CEH activity assayed at pH 5 could also be fit to a single exponential that yielded a target size of 71 +/- 14 kDa (n = 5). In contrast, the surviving CEH activity assayed at pH 7 was more complex. The data from six experiments were described as the sum of two exponentials, indicating that most of the activity is due to an entity that is three to four times larger and a minor amount to one that is half the size of the pH 5 enzy...
Research Interests:
Previous studies have indicated the presence of both neutral and acid, bile salt-independent retinyl ester hydrolases associated with plasma membrane and endosome fractions of rat liver homogenates. In the present studies, chylomicrons... more
Previous studies have indicated the presence of both neutral and acid, bile salt-independent retinyl ester hydrolases associated with plasma membrane and endosome fractions of rat liver homogenates. In the present studies, chylomicrons containing tritium-labeled retinyl esters were injected intravenously into rats in order to study the initial metabolism of retinyl esters during and after uptake into the liver. At various times after chylomicron injection, plasma was obtained and the liver was homogenized and subjected to analytical subcellular fractionation. Labeled retinyl esters were rapidly cleared from plasma (half-time approximately 10 min) and appeared in the liver. Within the liver, label first appeared in plasma membrane/endosomal fractions that were also enriched in both neutral and acid, bile salt-independent retinyl ester hydrolase activities. At no time were the labeled esters significantly associated with fractions enriched in lysosomes. Rather, it appeared that the la...
Research Interests:
Previous studies have demonstrated that homogenates of the livers of rats contain a neutral retinyl ester hydrolase activity that requires millimolar concentrations of bile salts for maximal in vitro activity. The enzymatic properties of... more
Previous studies have demonstrated that homogenates of the livers of rats contain a neutral retinyl ester hydrolase activity that requires millimolar concentrations of bile salts for maximal in vitro activity. The enzymatic properties of this neutral, bile salt-dependent retinyl ester hydrolase activity in liver homogenates are nearly identical to those observed in the present report for the in vitro hydrolysis of retinyl palmitate by purified rat pancreatic cholesteryl ester hydrolase (EC 3.1.1.13). Moreover, anti-rat pancreatic cholesteryl ester hydrolase IgG completely inhibits the bile salt-dependent retinyl ester hydrolase activity of rat liver homogenates whereas normal rabbit IgG does not. We also show that liver homogenates contain a neutral, bile salt-independent retinyl ester hydrolase activity that differs from the bile salt-dependent activity in that 1) its absolute activity does not vary markedly among individual rats, 2) it is not inhibited by antibodies to pancreatic ...
Research Interests:
Insulin resistance has been implicated in the pathogenesis of type 2 diabetes. High fat diets cause insulin resistance. Both metformin and pioglitazone are considered "insulin sensitizers" and used as antihyperglycemic agents... more
Insulin resistance has been implicated in the pathogenesis of type 2 diabetes. High fat diets cause insulin resistance. Both metformin and pioglitazone are considered "insulin sensitizers" and used as antihyperglycemic agents for type 2 diabetes treatment. The aim of this study is to Compare pioglitazone and metformin effects on carbohydrate metabolism and insulin sensitivity in diabetic and glucose intolerant rats on high fat diet. Male albino rats were randomized to seven groups. The 1st group received high carbohydrate diet (control). The 2nd, 3rd and 4th groups received high sunflower oil diets for 6 weeks and either left untreated, or given pioglitazone or metformin during the last 3 weeks. The 5th, 6th, and 7th groups were made diabetic by STZ injection on day 15 of the 6 weeks-high fat diet regimen. They were either left untreated, or given pioglitazone or metformin during the last 3 weeks. High-fat diet induced glucose intolerance; represented by increase of serum ...
Research Interests:
Research Interests:
ABSTRACT Background. This study aimed to examine the contribution of Asymmetric Dimethylarginine (ADMA), an endogenous inhibitor of nitric oxide synthase and a novel marker of vascular endothelial dysfunction and atherosclerosis, and... more
ABSTRACT Background. This study aimed to examine the contribution of Asymmetric Dimethylarginine (ADMA), an endogenous inhibitor of nitric oxide synthase and a novel marker of vascular endothelial dysfunction and atherosclerosis, and Thrombin-Activatable Fibrinolysis Inhibitor (TAFI), a risk factor for venous thrombosis, in the predisposition of coronary restenosis after stent implantation in coronary artery disease (CAD) patients. Methods. Thirty seven patients with CAD were recruited from the department of cardiology at Kobry El Obba Military Hospital, Cairo, Egypt. The patients were hospitalized for coronary angiography and coronary stenting (CS). Overnight fasting blood samples were collected from the patients before CS and four months later for the determination of plasma ADMA and TAFI levels by ELISA technique. The patients underwent follow up coronary angiography to reveal in-stent restenosis. Results. Mean plasma levels of ADMA were shown to be significantly higher in CAD patients as compared with that reported for healthy subjects in previous studies. In addition, ADMA levels were shown to be significantly higher (p=0.01) by 30% in CAD patients four months after CS as compared to those before stenting. CAD patients who developed in-stent restenosis during angiographic follow-up (n=22) had 35% increase in ADMA levels (p=0.01) after CS. In non-diabetic CAD patients who developed in-stent restenosis (n=17), ADMA levels were higher by 19% (p=0.049) after CS. On the other hand, TAFI levels were not significantly changed after CS in CAD patients or any of the above subgroups. Conclusions. ADMA, but not TAFI, is linked to the predisposition of in-stent restenosis after CS.
ABSTRACT Cardiovascular disease (CVD) is one of the leading causes of death among Egyptians. Thus there is always an immense need for exploring the genetic and environmental factors contributing in the development of this disease. Among... more
ABSTRACT Cardiovascular disease (CVD) is one of the leading causes of death among Egyptians. Thus there is always an immense need for exploring the genetic and environmental factors contributing in the development of this disease. Among these factors emerge modulation of nitric oxide (NO) homeostasis and oxidative stress as central players according to recent reports. A range of biochemical disturbances including reduced availability of NO and oxidative stress has been shown to be associated with endothelial dysfunction (ED). Recent evidence indicates that ED may be genetically determined. Many studies described the contribution of ED in the predisposition of CVD, in particular myocardial infarction. Therefore, studies in our lab are running to identify the role of genetic polymorphisms in enzymes and regulatory proteins related to NO metabolism and oxidative stress in the predisposition of early-onset myocardial infarction (MI) in Egyptians. Results on the association of DDAH2 gene polymorphism with the incidence of cardiovascular disease in Egyptians will be presented as representative data. Our aim is to contribute through this information in the primary prevention of MI. Identification of genetically susceptible subjects will help in possible interventions (environmental) to undermine the possibility of CVD occurrence
Research Interests:
l-Arginine is one of the most metabolically versatile amino acids. In addition to its role in the synthesis of nitric oxide, l-arginine serves as a precursor for the synthesis of polyamines, proline, glutamate, creatine, agmatine and... more
l-Arginine is one of the most metabolically versatile amino acids. In addition to its role in the synthesis of nitric oxide, l-arginine serves as a precursor for the synthesis of polyamines, proline, glutamate, creatine, agmatine and urea. Several human and experimental animal studies have indicated that exogenous l-arginine intake has multiple beneficial pharmacological effects when taken in doses larger than
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Endothelial dysfunction is now widely recognized as an early marker of cardiovascular disease, making its treatment, or complete avoidance, an emerging, interesting therapeutic target. This study investigated the ability of the highly... more
Endothelial dysfunction is now widely recognized as an early marker of cardiovascular disease, making its treatment, or complete avoidance, an emerging, interesting therapeutic target. This study investigated the ability of the highly intriguing amino acid L-arginine to influence endothelial function. Its therapeutic potential is also compared to that of known cardiovascular medications, namely nitroglycerin [a nitric oxide (NO) donor] and enalapril [an angiotensin-converting enzyme (ACE) inhibitor]. Fifty male New Zealand rabbits were included in the study, divided into 5 equal groups: control, hypercholesterolemia (untreated), hypercholesterolemia (+L-arginine), hypercholesterolemia (+enalapril), and hypercholesterolemia (+nitroglycerin). Biochemical investigations included measurement of circulating NOx, malondialdehyde (MDA), and lipid profile markers, as well as dimethylarginine dimethylaminohydrolase (DDAH) and ACE activities. Furthermore, aortic ACE activity and blood platele...
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests: Oils, Free Radical, Liver, Animals, Male, and 7 moreGlutathione, Rats, Seeds, Time Factors, Pharmacological, Adjuvant Arthritis, and Indomethacin
Research Interests:
Research Interests:
Research Interests:
Research Interests: Folk Medicine, Medicinal Plants, Starch, Molecular and cellular biology, Kidney, and 20 moreBlood Glucose, Liver, Animals, Male, Fruit, Enzyme, Plant extracts, Rats, Seeds, Carbohydrate metabolism, Oral Hypoglycemic Agents, Wistar Rats, Plant Extract, Hypoglycemic Effect, Streptozotocin, Diabetic Rat, Glycogen, Molecular and Cellular Biochemistry, Trigonella, and Biochemistry and cell biology(Blood Glucose, Liver, Animals, Male, Fruit, Enzyme, Plant extracts, Rats, Seeds, Carbohydrate metabolism, Oral Hypoglycemic Agents, Wistar Rats, Plant Extract, Hypoglycemic Effect, Streptozotocin, Diabetic Rat, Glycogen, Molecular and Cellular Biochemistry, Trigonella, and Biochemistry and cell biology)
(Blood Glucose, Liver, Animals, Male, Fruit, Enzyme, Plant extracts, Rats, Seeds, Carbohydrate metabolism, Oral Hypoglycemic Agents, Wistar Rats, Plant Extract, Hypoglycemic Effect, Streptozotocin, Diabetic Rat, Glycogen, Molecular and Cellular Biochemistry, Trigonella, and Biochemistry and cell biology)
Research Interests:
Research Interests: Chronic kidney disease, Oxidative Stress, Cardiovascular disease, Peroxidase, Humans, and 19 moreHemodialysis, Male, Risk factors, Homocysteine, Endothelial dysfunction, Clinical Sciences, Aged, Middle Aged, Cardiovascular Risk Factor, Arginine, Cardiovascular Diseases, Risk Factors, Serum Asymmetric Dimethylarginine (ADMA), Chronic Kidney Failure, Myeloperoxidase, Malondialdehyde, Renal Dialysis, Case Control Studies, and Conservative treatment(Hemodialysis, Male, Risk factors, Homocysteine, Endothelial dysfunction, Clinical Sciences, Aged, Middle Aged, Cardiovascular Risk Factor, Arginine, Cardiovascular Diseases, Risk Factors, Serum Asymmetric Dimethylarginine (ADMA), Chronic Kidney Failure, Myeloperoxidase, Malondialdehyde, Renal Dialysis, Case Control Studies, and Conservative treatment)
(Hemodialysis, Male, Risk factors, Homocysteine, Endothelial dysfunction, Clinical Sciences, Aged, Middle Aged, Cardiovascular Risk Factor, Arginine, Cardiovascular Diseases, Risk Factors, Serum Asymmetric Dimethylarginine (ADMA), Chronic Kidney Failure, Myeloperoxidase, Malondialdehyde, Renal Dialysis, Case Control Studies, and Conservative treatment)