Oxygen free radical and lipid peroxides (oxidative stress) are highly reactive and represent very damaging compounds. Oxidative stress could be a major contributing factor to the tissue injury and fibrosis that characterize Crohn's disease. An imbalance between increased reactive oxygen species levels and decreased antioxidant defenses occurs in Crohn's patients. Decreased blood levels of vitamins C and E and decreased intestinal mucosal levels of CuZn superoxide dismutase, glutathione, vitamin A, C, E, and β-carotene have been reported for Crohn's patients. Increased levels of proinflammatory cytokines, such as interleukin-1 and -8 and tumor necrosis factor, have been detected in inflammatory bowel disease. Oxidative stress significantly increased the production of neutrophils, chemokines, and interleukin-8. These effects were inhibited by antioxidant vitamins and arachidonic acid metabolite inhibitors in human intestinal smooth muscle cells isolated from the bowels of Crohn's disease patients. The main pathological feature of Crohn's disease is an infiltration of polymorphonuclear neutrophils and mononuclear cells into the affected part of the intestine. Activated neutrophils produce noxious substances that cause inflammation and tissue injury. Due to the physiological and biochemical actions of reactive oxygen species and lipid peroxides, many of the clinical and pathophysiological features of Crohn's disease might be explained by an imbalance of increased reactive oxygen species and a net decrease of antioxidant molecules. This review describes the general concepts of free radical, lipid peroxide and antioxidant activities and eventually illustrates their interferences in the development of Crohn's strictures.
Obstructive sleep apnea (OSA) is associated with cardiovascular morbidity and mortality and many other physiological and immunological disorders. An increase in hypoxia due to OSA may cause generation of reactive oxygen species (ROS). ROS are toxic to biomembranes and may lead to peroxidation of lipids. An increase in systemic biomarkers of inflammation and oxidative stress has been found in patients with OSA. The first aim of this study was to test the hypothesis that OSA is linked to increased oxidative stress (lipid peroxidation) and decreased antioxidant defense [superoxide dismutase (SOD)]. The second aim was to measure the serum levels of neutrophil chemokines [interleukin-8 (IL-8)], and granulocyte chemotactic protein-2 (GCP-2) in OSA patients. Twenty five patients with severe OSA and 17 healthy subjects were recruited. IL-8 and GCP-2 were measured in the serum by a specific enzyme immunoassay kit. Oxidative stress level was quantitated by measurement of thiobarbituric acid reactive substances. SOD enzymatic activity was measured by purely chemical system based on NAD(P)H oxidation. Mean SOD and lipid peroxidation concentrations of patients were not significantly different from those of control subjects (0.29+/-0.015 vs 0.31+/-0.01 U/ml and 4.64+/-0.57 vs 4.62+/-0.54 mmol/ml, respectively). Higher concentrations of IL-8 and GCP-2 were found in OSA patients (198.8+/-4.76 vs 180.83+/-3.38 and 383.34+/-46.19 vs 218+/-13.16 pg/ml, respectively, p<0.005). The present study does not support the hypothesis that OSA is linked to increased oxidative stress and decreased antioxidant defense. On the other hand, it suggests that systemic inflammation characterizes OSA patients.
We aimed to assess the effect of Islamic intermittent fasting, during and outside of Ramadan, on plasma levels of leptin and ghrelin while controlling for several potential confounding variables. Eight healthy male volunteers with a mean age of 26.6±4.9 years reported to the sleep disorders center (SDC) at King Saud University on four occasions: 1) adaptation; 2) 4 weeks before Ramadan while performing Islamic fasting for 1 week (baseline fasting) (BLF); 3) 1 week before Ramadan (non-fasting baseline) (BL); and 4) during the second week of Ramadan while fasting. Plasma leptin and ghrelin levels were measured using enzyme-linked immunoassays at 22:00, 02:00, 04:00, 06:00, and 11:00. During BLF, there were significant reductions in plasma leptin concentrations at 22:00 and 02:00 compared with the baseline concentrations (at 22:00: 194.2±177.2 vs. 146.7±174.5; at 02:00: 203.8±189.5 vs. 168.1±178.1; p<0.05). During Ramadan, there was a significant reduction in plasma leptin levels at 22:00 (194.2±177.2 vs. 132.6±130.4, p<0.05). No significant difference in plasma ghrelin concentrations was detected during the BL, BLF, or Ramadan periods. Cosinor analyses of leptin and ghrelin plasma levels revealed no significant changes in the acrophases of the hormones during the three periods. The nocturnal reduction in plasma leptin levels during fasting may be the result of the changes in meal times during fasting.
Increased levels of plasma MDA in IBD is an important indication of oxidative stress. Patients with Crohn's disease are more susceptible to oxidative stress than patients with ulcerative colitis.
PurposeThis study aimed to assess the effect of diurnal intermittent fasting (DIF) during and outside of the month of Ramadan on plasma levels of interleukin (IL)-1β, IL-6, and IL-8, while controlling for sleep/wake pattern, sleep length and quality, meal composition, energy consumption and expenditure, and light exposure. DIF outside of the month of Ramadan was performed to evaluate the effect of DIF in the absence of the way of life accompanying Ramadan.MethodsTwelve healthy male volunteers with a mean age of 25.1 ± 2.5 years arrived to the sleep laboratory on 4 times: 1) adaptation, 5 weeks before Ramadan; 2) 4 weeks before Ramadan while performing DIF for 1 week (fasting outside of Ramadan; FOR); 3) 1 week before Ramadan (non-fasting baseline; non-fasting BL); and 4) After completing 2 weeks of Ramadan while performing DIF. Plasma levels of cytokines were assessed using enzyme-linked immunoassays at 22:00, 02:00, 04:00, 06:00, and 11:00.ResultsDuring DIF, there was a significant decrease in the levels of cytokines, particularly, IL-1β and IL-6, in most measurements compared to non-fasting BL. This reduction was more obvious during the FOR period. There were no significant changes in the circadian phase of the measured cytokines reflected by the acrophase of the measured variables during fasting (FOR and Ramadan) compared to non-fasting BL.ConclusionUnder controlled conditions, DIF led to significantly decreased plasma levels of cytokines (IL-1β, IL-6, and IL-8), particularly IL-1β and IL-6 across 24 h. DIF had no effect on the circadian patterns of the measured cytokines as shown by cosinor analysis.
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