Othman Al-Shboul

The importance of interstitial cells of cajal in the gastrointestinal tract.

Gastrointestinal (GI) motility function and its regulation is a complex process involving collaboration and communication of multiple cell types such as enteric neurons, interstitial cells of Cajal (ICC), and smooth muscle cells. Recent advances in GI research made a better understanding of ICC function and their role in the GI tract, and studies based on different types of techniques have shown that ICC, as an integral part of the GI neuromuscular apparatus, transduce inputs from enteric motor neurons, generate intrinsic electrical rhythmicity in phasic smooth muscles, and have a mechanical sensation ability. Absence or improper function of these cells has been linked to some GI tract disorders. This paper provides a general overview of ICC; their discovery, subtypes, function, locations in the GI tract, and some disorders associated with their loss or disease, and highlights some controversial issues with regard to the importance of ICC in the GI tract.

Effect of oxidative stress on Rho kinase II and smooth muscle contraction in rat stomach

Recent studies have shown that both Rho kinase signaling and oxidative stress are involved in the pathogenesis of a number of human diseases, such as diabetes mellitus, hypertension, and atherosclerosis. However, very little is known about the effect of oxidative stress on the gastrointestinal (GI) smooth muscle Rho kinase pathway. The aim of the current study was to investigate the effect of oxidative stress on Rho kinase II and muscle contraction in rat stomach. The peroxynitrite donor 3-morpholinosydnonimine (SIN-1), hydrogen peroxide (H2O2), and peroxynitrite were used to induce oxidative stress. Rho kinase II expression and ACh-induced activity were measured in control and oxidant-treated cells via specifically designed enzyme-linked immunosorbent assay (ELISA) and activity assay kits, respectively. Single smooth muscle cell contraction was measured via scanning micrometry in the presence or absence of the Rho kinase blocker, Y-27632 dihydrochloride. All oxidant agents significantly increased ACh-induced Rho kinase II activity without affecting its expression level. Most important, oxidative stress induced by all three agents augmented ACh-stimulated muscle cell contraction, which was significantly inhibited by Y-27632. In conclusion, oxidative stress activates Rho kinase II and enhances contraction in rat gastric muscle, suggesting an important role in GI motility disorders associated with oxidative stress.

The role of free radicals and reactive species following traumatic brain injury

Abstract Introduction Traumatic brain injury is a leading cause of mortality and morbidity worldwide. Even though the primary phase of traumatic brain injury is mechanical and not amenable to intervention, the secondary phase is composed of a cascade of pathological and biochemical mechanisms that culminate in loss of neuronal functions. Among these secondary mechanisms of injury is the excess generation of free radicals and reactive species. Many reports in the literature documented the formation of oxygen and nitrogen free radicals and reactive species following traumatic brain injury. The formation of these reactive species following traumatic brain injury was further validated by detecting their footprints in traumatised neural tissues such as lipid peroxidation and protein nitration and carbonylation. This review aims to highlight the post-traumatic generation of free radicals and reactive species and discuss their role in propagating other secondary injury cascades. Conclusion The formation of free radicals and reactive species is a significant event after traumatic brain injury and is implicated in accentuating other elements of the secondary injury cascades including mitochondrial dysfunction, Ca++ dysregulation and activation of cellular proteases. The significance of these reactive species has been validated by many reports showing the virtues of scavenging these reactive species and/or their reactive by-products as a potential cure for traumatic brain injury.

Lower Levels of Serum Adiponectin and the T Allele of rs1501299 of the ADIPOQ Gene Are Protective against Polycystic Ovarian Syndrome in Jordan

Background Polycystic ovary syndrome (PCOS) is a common reproductive disorder. Obesity, which is linked with lower adiponectin levels, increases a womans risk of developing PCOS; however, the association between adiponectin and PCOS is controversial. Adiponectin levels could be affected by single nucleotide polymorphisms (SNPs) in the ADIPOQ gene. This study aimed to test the relationship between serum adiponectin and PCOS in Jordan and the association between the rs2241766, rs1501299, and rs266729 SNPs in the ADIPOQ gene and PCOS. Methods One hundred and fifty-four women with PCOS and 149 age- and body mass index–matched normally menstruating controls were recruited. Serum adiponectin levels were measured using enzyme-linked immunosorbent assay. Genotyping was performed using polymerase chain reaction–restriction fragment length polymorphism analysis. Results Serum adiponectin levels were significantly lower (P=0.0064) in PCOS women and rs1501299 (+276 G/T) genotype distributions were significantly different (P=0.01) between them and normally menstruating women. Multivariate analysis revealed that adiponectin levels remained significantly lower in PCOS women (P=0.001; odds ratio [OR], 0.9; 95% confidence interval [CI], 0.84–0.96). The GT genotype of rs1501299 increased the risk of PCOS (P<0.001; OR, 5.46; 95% CI, 2.42–12.33) and increased the risk of PCOS by three-fold (P<0.001; OR, 3.00; 95% CI, 1.36–6.60) relative to the TT genotype. The GG genotype increased the risk of PCOS as well (P<0.001; OR, 3:00; 95% CI, 1.36–6.60). Conclusion PCOS is associated with lower serum adiponectin levels independent of age and body mass index. The T allele of the rs1501299 (+276 G/T) SNP of the ADIPOQ gene protects against PCOS.

Serum Branched Chain Amino Acids Are Associated with Type 2 Diabetes Mellitus in Jordan

Background Diabetes mellitus is a global public health problem that is caused by the lack of insulin secretion (type 1) or resistance to its action (type 2). A low insulin-to-glucagon ratio predicts an increase in the serum levels of branched chain amino acids, a feature confirmed in several populations. This relationship has not been assessed in Jordan. The objective of this study was to investigate the association between serum branched chain amino acids and type 2 diabetes mellitus in patients in Jordan. Methods Two hundred type 2 diabetes mellitus patients and an additional 200 non-diabetic controls were recruited. Age, body mass index, and waist circumference of the subjects were recorded. Branched chain amino acid, total cholesterol, and triglyceride levels were measured from the collected serum samples. Results Serum branched chain amino acid levels were significantly higher in type 2 diabetes mellitus patients than in non-diabetes individuals (P<0.0001). In binomial regression analysis, serum branched chain amino acid levels remained significantly associated with diabetes mellitus and increased its risk (odds ratio, 1.004; 95% confidence interval, 1.001–1.006; P=0.003). Conclusion Type 2 diabetes mellitus is associated with higher branched chain amino acid levels in Jordan independent of age, sex, body mass index, waist circumference, and total serum cholesterol and serum triglyceride levels.

Phenelzine reduces the oxidative damage induced by peroxynitrite in plasma lipids and proteins

Abstract Peroxynitrite is a reactive nitrogen species produced in the intravascular compartment from superoxide anion and nitric oxide. Peroxynitrite destroys blood plasma proteins and membranes of red blood cells and of platelets. This explains why excessive production of peroxynitrite contributes to diseases and to ageing. Therapeutics that antagonize peroxynitrite may delay ageing and the progression of disease. We developed an in vitro assay that allows the investigation of the oxidative damage caused by peroxynitrite in the intravascular compartment. This assay correlates the damage with the rate of formation of protein carbonyl groups, 3-nitrotyrosine (3-NT) and thiobarbituric acid reactive substances. Using this assay, we evaluated the ability of phenelzine, a scavenger of reactive aldehydes, to antagonize the effects of peroxynitrite. Herein, we showed that phenelzine significantly decreased the lipid peroxidative damage caused by peroxynitirite in blood plasma and platelets. Moreover, it inhibited carbonyl group and 3-NT formation in blood plasma and platelet proteins.

Glucagon-like peptide-1 exerts anti-inflammatory effects on mouse colon smooth muscle cells through the cyclic adenosine monophosphate/nuclear factor-κB pathway in vitro

Background Intestinal smooth muscle cells (SMCs) undergo substantial morphological, phenotypic, and contractile changes during inflammatory bowel disease (IBD). SMCs act as a source and target for different inflammatory mediators, however their role in IBD pathogenesis is usually overlooked. Glucagon-like peptide-1 (GLP-1) is an incretin hormone reported to exert multiple anti-inflammatory effects in different tissues including the gastrointestinal tract through various mechanisms. Aim The aim of this research is to explore the effect of GLP-1 analog exendin-4 on the expression and secretion of inflammatory markers from mouse colon smooth muscle cells (CSMCs) after stimulation with lipopolysaccharide (LPS). Materials and methods Freshly isolated CSMCs from male BALB/c mice were cultured in DMEM and treated with vehicle, LPS (1 μg/mL), LPS+exendin-4 (50 nM), or LPS+exendin-4 (100 nM) for 24 h. Expression of inflammatory cytokines was then evaluated by antibody array membrane. Results CSMCs showed basal expression of several cytokines which was enhanced with the induction of inflammation by LPS. However, exendin-4 (50 and 100 nM) significantly (p<0.05) reduced the expression of multiple cytokines including tumor necrosis factor-α (TNF-α), interleukin-1α (IL-1α), T cell activation gene-3 (TCA-3), stromal cell-derived factor-1 (SDF-1), and macrophage colony stimulating factor (M-CSF). To confirm these results, expression of these cytokines was further assessed by enzyme-linked immunosorbent assay and real-time polymerase chain reaction and similar results were also observed. Moreover, secretion of TNF-α and IL1-α into the conditioned media was significantly downregulated by exendin-4 when compared to LPS-treated cells. Furthermore, LPS increased NF-κB phosphorylation, while exendin-4 significantly reduced levels of NF-κB phosphorylation. Conclusion These data indicate that GLP-1 analogs can exert significant anti-inflammatory effects on CSMCs and can potentially be used as an adjunct treatment for inflammatory bowel conditions.

Association of Adiponectin and rs1501299 of the ADIPOQ Gene with Prediabetes in Jordan

Type 2 diabetes mellitus (T2DM) is a worldwide health problem caused by resistance to insulin action. This chronic debilitating diseaseis preceded by a stage, known as prediabetes, in which a healthy lifestyle can delay the disease. The discovery of biochemical changes in prediabetes is important to identify individuals at risk of developing T2DM and in explaining disease pathogenesis. Adiponectin is secreted by fat cells and is linked with insulin resistance. Adiponectin levels are dysregulated in prediabetic subjects. This relationship had not been tested in Jordan. We recruited 130 subjects with prediabetes and 130 control subjects. We measured serum levels of adiponectin and genotyped subjects for three single nucleotide polymorphisms (SNPs) in the ADIPOQ gene; rs266729, rs1501299 and rs2241766. In multivariate analysis, we found that serum adiponectin lowers the risk of prediabetes (p = 0.002; odds ratio (OR), 0.764; 95% confidence interval (CI), 0.646–0.905). The rs1501299 SNP of the ADIPOQ gene was associated with prediabetes in our population (p = 0.041). Specifically, in multivariate analysis, the GT genotype of rs1501299 increased the risk of prediabetes (p = 0.010; OR, 2.350; 95% CI, 1.231–4.486) as well as the TT genotype (p = 0.006; OR, 4.774; 95% CI, 1.551–14.693). Our findings indicate that serum adiponectin and SNPs in the ADIPOQ gene are associated with prediabetes in Jordan.

The role of the RhoA/ROCK pathway in gender-dependent differences in gastric smooth muscle contraction

Gender-related differences in various gastric functions and diseases have been reported, with women having a higher prevalence of gastrointestinal disturbances than men. The aim of this study was to investigate sex-dependent differences in activation of the Rho-associated protein kinase (ROCK; RhoA/Rho kinase) pathway and muscle contraction in the stomach using single gastric smooth muscle cells (GSMC) from male and female Sprague–Dawley rats. Expression of ROCK1 and ROCK2 protein and acetylcholine (ACh)-induced activation of RhoA and ROCK were measured using a specifically designed enzyme-linked immunosorbent assay and activity assay kits, respectively. Contraction of a single GSMC was measured by scanning micrometry in the presence or absence of the ROCK inhibitor Y27632 dihydrochloride. ACh-induced activation of RhoA and ROCK and subsequent contraction were greater in male rats than in female rats but neither was related to differences in the expression of ROCK1 or ROCK2 or total RhoA amount. Most important, Y27632 inhibited and abolished differences in ACh-induced contraction in both sexes. In conclusion, increased ACh-induced contraction in the GSMC of male rats is attributable to greater RhoA/ROCK activation independent of differences in the expression of ROCK isoforms or total RhoA.

Non-genomic effects of progesterone on Rho kinase II in rat gastric smooth muscle cells

Various studies have shown that pregnancy is associated with gastrointestinal complaints that might result from disturbance of the normal contractile pattern of smooth muscle. Progesterone is an important steroid hormone, which plays a crucial role in female pregnancy. Progesterone affects muscle cells by genomic mechanisms, through nuclear receptors, and non-genomic mechanisms, through unidentified pathways. Non-genomic actions were defined as those occurring within 10 min of progesterone exposure. The aim of the present study was to investigate the non-genomic effect of progesterone on Rho kinase II activity in gastric smooth muscle. Single smooth muscle cells of the stomach obtained from Sprague Dawley rats were used. Dispersed gastric smooth muscle cells were treated with progesterone or acetylcholine (ACh) separately. Cells designated for progesterone treatment were incubated with 1 μM progesterone for 10 min. Rho kinase II expression and both basal and ACh-induced Rho kinase II activity were measured via specifically designed enzyme-linked immunosorbent assay (ELISA) and activity assay kits respectively in both control and progesterone-treated groups. Progesterone inhibited the ACh-induced, but not the basal, Rho kinase II activity in dispersed gastric smooth muscle cells without affecting its expression level. This study suggested that progesterone can rapidly affect the contractile activity of isolated gastric smooth muscle cells in rats via inhibition of the Rho kinase II pathway.