Mohamed Z. Gad

Protective effect of vitamin E, β-carotene and N-acetylcysteine from the brain oxidative stress induced in rats by lipopolysaccharide

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 Na+, K+-ATPase and contents of cholesterol and phospholipids were not altered. Administration of the aforementioned antioxidants prior to LPS injection ameliorated the oxidative stress by reducing levels of MDA, restoring GSH content and normalizing the mitochondrial/cytosolic hexokinase ratio in the brain in addition to lowering levels of plasma corticosterone and glucose. In conclusion, this study showed the increased free radical generation during infections and LPS-induced stress. It also suggests that brain oxidative status and energy is disturbed.

Biochemical study of the anti-diabetic action of the Egyptian plants fenugreek and balanites.

Fenugreek and Balanites are two plants commonly used in Egyptian folk medicine as hypoglycemic agents. In the present study, the effects of 21 days oral administration of Fenugreek seed and Balanites fruit extracts (1.5 g/kg bw) on the liver and kidney glycogen content and on some key liver enzymes of carbohydrate metabolism in STZ-diabetic rats were studied. In addition, the effects of these two plant extracts on the intestinal α-amylase activity in vitro and starch digestion and absorption in vivo were also examined. Results indicated that single injection of STZ (50 mg/kg bw) caused 5-folds increase in the blood glucose level, 80% reduction in serum insulin level, 58% decrease in liver glycogen and 7-folds increase in kidney glycogen content as compared to the normal levels. The activity of glucose-6-phosphatase was markedly increased, whereas, the activities of both glucose-6-phosphate dehydrogenase and phospho-fructokinase were significantly decreased in the diabetic rat liver. Administration of Fenugreek extract to STZ-diabetic rats reduced blood glucose level by 58%, restored liver glycogen content and significantly decreased kidney glycogen as well as liver glucose-6-phosphatase activity. Meanwhile, Balanites extract reduced blood glucose level by 24% and significantly decreased liver glucose-6-phosphatase activity in diabetic rats. On the other hand, our results demonstrated that both the Fenugreek and Balanites extracts were able to in vitro inhibit α-amylase activity in dose-dependent manner. Fenugreek was more potent inhibitor than Balanites. This inhibition was reversed by increasing substrate concentration in a pattern which complies well with the effect of competitive inhibitors. Furthermore, this in vitro inhibition was confirmed by in vivo suppression of starch digestion and absorption induced by both plant extracts in normal rats. These findings suggest that the hypoglycemic effect of Fenugreek and Balanites is mediated through insulinomimetic effect as well as inhibition of intestinal α-amylase activity.

Effect of pumpkin-seed oil on the level of free radical scavengers induced during adjuvant-arthritis in rats

Pumpkin-seed oil (PSO), a natural supplement rich with antioxidant ingredients, was given to rats in which arthritis was induced using Freunds complete adjuvant. Its effect was compared with that of indomethacin, as a classical anti-inflammatory agent. Two experimental patterns were studied, an acute phase that was applied only with PSO and a chronic phase applied for both PSO and indomethacin. Compared to normal untreated rats, it was shown that the induction of arthritis caused a decrease in serum sulphhydryl groups, with an increase in serum ceruloplasmin in both phases. Blood glutathione was first elevated in the acute phase, then its level was reduced in the chronic phase. Serum N-acetyl-beta-D-glucosaminidase activity was elevated only at the acute phase, while plasma total proteins and albumin were reduced at the chronic phase. Liver glucose-6-phosphate dehydrogenase activity was markedly increased, while no changes were observed in the levels of liver lipid peroxides and glutathione. These changes in the studied parameters were attributed to the superoxides and free radicals during arthritic inflammation. Administration of PSO succeeded in modulating most of the altered parameters affected during arthritis, especially at the chronic phase. Also, a remarkable inhibition of paw oedema was observed. A similar pattern was obtained upon treatment with indomethacin except that indomethacin markedly elevated liver lipid peroxides levels. Concurrent administration of PSO with indomethacin caused no changes in the parameters studied compared to that induced by treatment with indomethacin alone.

Effect of various stressors on the level of lipid peroxide, antioxidants and Na +, K+-ATPase activity in rat brain

The level of malondialdehyde (MDA), an index of lipid peroxidation, and the antioxidants superoxide dismutase (SOD) and glutathione (GSH), as well as the activity of Na+, K+-ATPase, were assessed in whole rat brain after immobilization, anemic hypoxia (NaNO2) and 72 h starvation. The effect of these stressors on plasma glucose and corticosterone levels was also observed. Hypoxia and starvation stimulated the lipidj peroxide formation in braini as indicated by an increase in the level of MDA, being higher after starvation than hypoxia. Brain SOD activity was also increased in response to hypoxia and starvation while GSH content was only diminished ini hypoxia. However, neither MDA nor antioxidants were affected by immobilization. On the other hand, the activity of brain Na+, K+-ATPase was significantly increased by immobilization and hypoxia but decreased in starvation. A similar pattern of change was also observed in plasma glucose and corticosterone levels in response to these stressors. These results elucidate differences in the biochemical response of animals towards various types of stress, with increased lipid peroxide formation in hypoxia and starvation.

Lipid peroxidation and lysosomal integrity in different inflammatory models in rats: the effects of indomethacin and naftazone.

In the present study, the potential involvement of lipid peroxidation and disruption of lysosomal integrity in the pathogenesis of different experimental models of inflammation was examined. The chosen models were carrageenan-induced paw oedema, carrageenan granuloma pouch (acute phase) and Freunds adjuvant-induced arthritis in rats. The pharmacological and biochemical effects of naftazone, a lysosomal membrane stabilizer and indomethacin, a standard anti-inflammatory agent were evaluated with regard to paw oedema volume, serum and exudate activities of the lysosomal enzyme N-acetyl-beta-D-glucosaminidase (NAG), in addition to serum and liver lipid peroxide (LP) levels. Intraperitoneal administration of the test drugs, in rats subjected to inflammation, produced: (1) a significant inhibition of carrageenan-induced paw oedema, (2) a marked reduction of the paw oedema of the Freunds adjuvant arthritis animals, (3) a remarkable decrease of lysosomal leakage of NAG into the exudate of carrageenan granuloma pouch, (4) a slight, but significant, reduction of NAG activity in the serum of rats subjected to carrageenan inflammation, and (5) a reduction of the serum level of LP that was elevated in adjuvant-induced arthritic rats. The level of liver LP was altered by either drugs in an opposite manner; while naftazone lowered hepatic LP, indomethacin markedly elevated its level. The results of the present investigation revealed that lipid peroxidation and disruption of lysosomal integrity are implicated in the pathogenesis of inflammatory processes, and the protection against these deleterious effects imparted both drugs significant anti-inflammatory activity.

Oxidative Stress and Asymmetric Dimethylarginine Are Associated with Cardiovascular Complications in Hemodialysis Patients: Improvements by L-Arginine Intake

Background/Aim: High incidence of cardiovascular disease (CVD) in chronic kidney disease (CKD) patients is a result of an interlaced relation between oxidative stress, endothelial dysfunction (ED) and inflammation. This study tries to investigate the development of these processes in CKD patients receiving conservative treatment or on hemodialysis (HD). We also examined the modulating effect of oral L-arginine in HD patients having CVD. Methods: The study included 12 healthy volunteers and 63 renal patients divided into 15 renal impairment, 18 HD free of CVD, and 30 HD suffering from CVD (HD+CVD). Of the latter, 15 patients were given oral L-arginine (15 g/day, 5 g t.i.d.) for 1 month. Blood levels of asymmetric dimethylarginine (ADMA), malondialdehyde (MDA), and homocysteine and myeloperoxidase activity (MPO) were estimated. Results: ADMA, MDA and homocysteine were significantly elevated in renal impairment group. HD and HD+CVD patients experienced higher levels, along with high MPO activity. Significant reduction by 21, 46, 11, and 26%, respectively, in the aforementioned parameters was observed in HD+CVD patients following L-arginine intake. Conclusion:We recommend considering ADMA, MDA, homocysteine and MPO as potentially important cardiovascular risk factors in CKD patients, and focus the attention to the cardiovascular advantages of L-arginine in these patients.

Overexpression of NMDAR2B in an inflammatory model of Alzheimer's disease: Modulation by NOS inhibitors

BACKGROUND Alzheimers disease (AD) is a common form of age-related dementia, characterized by deposition of amyloid Aβ plaques, neuroinflammation and neurodegeneration. N-methyl-D-aspartate receptors (NMDAR) are postsynaptic glutamate receptors that play a role in memory formation and are targets for memantadine, an anti-AD drug. Nitric oxide (NO) signaling has been involved in both memory development through neuronal NO synthase (nNOS), and neuroinflammation through inducible NO synthase (iNOS) which mediates CNS inflammatory processes. AIM To study the expression of the NMDAR2B subunit in an inflammatory model of AD before and after treatment with NO modulators. MATERIALS AND METHODS AD was induced in mice by a single dose of lipopolysaccharide (LPS). Behavioral tests for spatial and non-spatial memories and locomotor activity were performed to assess disease severity and progression. The effects of L-NAME (general NOS inhibitor), 1400W (iNOS inhibitor), diflunisal (systemic anti-inflammatory drug that does not cross the blood brain barrier), and L-arginine, the substrate for NOS was determined. Immunohistochemistry was done to confirm AD and brain lysates were tested for Aβ formation, levels of NMDAR2B subunits, and brain NO levels. RESULTS Systemic LPS induced AD, as shown by cognitive impairment; increased levels of Aβ and concomitant increase in the brain NO concentrations. This was associated with overexpression of NMDAR2B. All tested drugs improved behavioral dysfunction, prevented Aβ formation and NMDAR overexpression, and lead to decrease in NO concentration in the brain. L-Arginine alone, however, did not produce similar improvements. CONCLUSION NMDAR2B subunits are overexpressed in an inflammatory model of AD and NO inhibitors ameliorate this expression.

A Comparative Metabolomics Approach Reveals Early Biomarkers for Metabolic Response to Acute Myocardial Infarction

Discovery of novel biomarkers is critical for early diagnosis of acute coronary syndrome (ACS). Serum metabolite profiling of ST-elevation myocardial infarction (STEMI), unstable angina (UA) and healthy controls was performed using gas chromatography mass spectrometry (GC/MS), solid-phase microextraction coupled to gas chromatography mass spectrometry (SPME-GC/MS) and nuclear magnetic resonance (1H-NMR). Multivariate data analysis revealed a metabolic signature that could robustly discriminate STEMI patients from both healthy controls and UA patients. This panel of biomarkers consisted of 19 metabolites identified in the serum of STEMI patients. One of the most intriguing biomarkers among these metabolites is hydrogen sulfide (H2S), an endogenous gasotransmitter with profound effect on the heart. Serum H2S absolute levels were further investigated using a quantitative double-antibody sandwich enzyme-linked immunosorbent assay (ELISA). This highly sensitive immunoassay confirmed the elevation of serum H2S in STEMI patients. H2S level discriminated between UA and STEMI groups, providing an initial insight into serum-free H2S bioavailability during ACS. In conclusion, the current study provides a detailed map illustrating the most predominant altered metabolic pathways and the biochemical linkages among the biomarker metabolites identified in STEMI patients. Metabolomics analysis may yield novel predictive biomarkers that will potentially allow for an earlier medical intervention.

Triangular relationship between single nucleotide polymorphisms in the CYP2R1 gene (rs10741657 and rs12794714), 25-hydroxyvitamin d levels, and coronary artery disease incidence

Abstract Objective: To investigate the relationship between the rs10741657 and rs12794714 polymorphisms in the CYP2R1 gene, 25(OH)D levels, and coronary artery disease (CAD) incidence. Methods: In total, 134 male patients with verified CAD were recruited, alongside 109 age- and sex-matched controls. Genotyping was performed by polymerase chain reaction-restriction fragment length polymorphism, using the corresponding restriction enzyme for each polymorphism, whereas 25(OH)D levels were analyzed by HPLC-UV. Results: 25(OH)D levels were significantly lower in patients. The genotypic and allelic distributions of the rs10741657 polymorphism were significantly different between patients and controls, whereas insignificant results were obtained for the rs12794714 polymorphism. Furthermore, rs10741657, but not rs12794714, predicted 25(OH)D levels. Conclusion: The rs10741657 polymorphism is a novel genetic marker for CAD.

Endothelial Nitric Oxide Synthase (G894T) Gene Polymorphism in a Random Sample of the Egyptian Population: Comparison with Myocardial Infarction Patients

AIM The aim of this study was to detect endothelial nitric oxide synthase (eNOS) Glu298Asp gene variants in a random sample of the Egyptian population, compare it with those from other populations, and attempt to correlate these variants with serum levels of nitric oxide (NO). The association of eNOS genotypes or serum NO levels with the incidence of acute myocardial infarction (AMI) was also examined. METHODS One hundred one unrelated healthy subjects and 104 unrelated AMI patients were recruited randomly from the 57357 Hospital and intensive care units of El Demerdash Hospital and National Heart Institute, Cairo, Egypt. eNOS genotypes were determined by polymerase chain reaction-restriction fragment length polymorphism. Serum NO was determined spectrophotometrically. RESULTS The genotype distribution of eNOS Glu298Asp polymorphism determined for our sample was 58.42% GG (wild type), 33.66% GT, and 7.92% TT genotypes while allele frequencies were 75.25% and 24.75% for G and T alleles, respectively. No significant association between serum NO and specific eNOS genotype could be detected. No significant correlation between eNOS genotype distribution or allele frequencies and the incidence of AMI was observed. CONCLUSION The present study demonstrated the predominance of the homozygous genotype GG over the heterozygous GT and homozygous TT in random samples of Egyptian population. It also showed the lack of association between eNOS genotypes and mean serum levels of NO, as well as the incidence of AMI.