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Pentoxifylline Inhibits Overflow and Reduces Intestinal Reperfusion Injury

The aim of this study was to determine the effects of pentoxifylline (Ptx) in reperfusion injury of the small bowel as a leukocyte stabilizer, free radical scavenger, and microcirculatory regulator. Ninety-six male Sprague-Dawley rats were used to determine the biochemical, histopathologic and blood flow changes of the reperfused small intestines after 30 minutes of a warm ischemic insult. Animals were divided into six groups: Sham (S), sham plus Ptx (SP), ischemia (I), ischemia plus Ptx (IP), reperfusion (R), and reperfusion plus Ptx (RP). Pentoxifylline was administered intraperitoneally at a dose of 50 mg/kg 15 minutes before ischemia. The superior mesenteric artery (SMA) was occluded distal to the right colic artery and collateral arcades were ligated as described by Megison. Sixty of the 96 rats (n = 10) were used to determine histopathologic changes, malondialdehyde (MDA), and myeloperoxidase (MPO) levels in tissue. Mucosal lesions were graded on a scale from 0 to 5 as described by Chiu. MDA and MPO levels of the intestinal mucosa were assayed to reflect the free radical formation and neutrophil sequestration, respectively. Thirty-six rats (n = 6) were used to measure blood flow changes of the intestine using 133Xe clearance technique. All data were presented as the mean values plus or minus the standard error of the means (means +/- sem). Although in the R group, mucosal injury score, blood flow, MPO, and MDA levels were higher significantly from the other groups (P < .05), in the RP group blood flow, MPO, and MDA levels were significantly decreased to the basal values (P < .05). Mucosal injury score of the RP group were lower than the reperfusion group but higher than the normal (P < .05). The authors conclude that pentoxifylline pretreatment before reperfusion stabilizes blood flow, decreases MPO and MDA levels to the normal, and attenuates but not completely prevents mucosal damage.

Comparison of Consequent Small Bowel Anastomoses After Transient Ischemia: An Experimental Study in Rats

BACKGROUND/PURPOSEnThe role of ischemia/reperfusion (I/R) damage on intestinal anastomotic healing remains to be precisely determined. The objective of this study was to investigate healing of small bowel anastomoses performed at different times after transient ischemia.nnnMETHODSnThirty male Wistar-Albino rats were investigated in five groups (four study and one control). Under general anesthesia, the superior mesenteric artery (SMA) was occluded for 40 minutes in the study rats. Biopsy specimens, to document I/R histopathology, were obtained before small intestinal anastomoses at 20 minutes (group 1), 90 minutes (group 2), 6 hours (group 3), and 24 hours (group 4) after reperfusion. In a control group, biopsy and intestinal anastomoses were performed after SMA dissection without occlusion. The rats were relaparotomized on the fifth day to determine in situ bursting pressures and to obtain specimens for hydroxyproline content and histopathologic evaluation.nnnRESULTSnHydroxyproline content and bursting pressures were compared statistically with Mann-Whitney U test. Although there was no statistical difference between the control group and group 1, there were significant differences (P < .05) between groups 2, 3, and 4, with both parameters decreasing as the duration after reperfusion increased.nnnCONCLUSIONnAnastomosis are less likely to leak when performed sooner rather than later after an ischemia/reperfusion event.

THE EFFECT OF 2-CHLOROADENOSINE ON LIPID PEROXIDE LEVEL DURING EXPERIMENTAL CEREBRAL ISCHEMIA-REPERFUSION IN GERBILS

Oxygen free radicals may be implicated in the pathogenesis of ischemia-reperfusion damage. It is known that 2-chloroadenosine (2-CADO) has neuromodulatory effects and prevents the neuronal damage seen in the period of postischemia reperfusion. However, direct effects of 2-CADO on lipid peroxidation have not been investigated previously. The attack on the cell membrane by free radicals leads to lipid peroxidation, which can be assayed by the malondialdehyde (MDA) level. The aim of this study was to determine the effect of 2-CADO therapy on lipid peroxidation in experimental forebrain ischemia and postischemia reperfusion in Mongolian gerbils. Cerebral ischemia was induced by a bilateral 30-mm occlusion of the common carotid arteries. 2-Chloroadenosine (0.6 mg/kg, IV) was administered 5 min subsequent to ischemia. Ischemia was followed by reperfusion for 30 min. The MDA level was measured by the thiobarbituric acid (TBA) test. Bilateral carotid artery occlusion for 30 min in gerbils resulted in no significant change in MDA level in the brain. The MDA level was higher in postischemia reperfusion than in the ischemic group. 2-Chloroadenosine treatment did not change the MDA level in the ischemic period. However, the MDA level recovered significantly upon 2-CADO therapy during reperfusion following ischemia. These results suggest that 2-CADO may offer some degree of protection against oxidative stress in cerebral ischemia-reperfusion damage.

The effect of Escherichia coli-derived lipopolysaccharides on plasma levels of malondialdehyde and 3-nitrotyrosine.

Abstract The aim of this study was to determine the effect of Escherichia coli ( E.coli)-derived lipopolysaccharide on rat plasma low density lipoprotein (LDL), malondialdehyde and 3-nitrotyrosine levels (an indicator of protein nitration). Six hours after intraperitoneal administration of E.coli, plasma LDL was measured electrophoretically and malondialdehyde level was measured by spectrophotometric method. Plasma malondialdehyde was significantly (p<0.001) elevated in E.coli-injected rats (4.97 ± 1.33; n=10) in comparison to control animals (1.83 ± 0.5; n=10). In addition, plasma 3-nitrotyrosine level, determined by reversephase HPLC, was also increased in the infected group (2.84 ± 1.17 to 0.22 ± 0.13; n=10). This increase was statistically significant (p<0.001). An increased level of oxidation of lipids and 3-nitrotyrosine was observed as a result of free radical-mediated damage in plasma. In conclusion, asymptomatic infections may increase the risk of atherosclerosis by inducing free radical formation and a consequent increase in the oxidation of LDL.

High-dose vitamin C supplementation accelerates the Achilles tendon healing in healthy rats

IntroductionThis experimental study was performed to assess, whether or not, vitamin C, required during the collagen synthesis, would influence the Achilles tendon healing in a healthy rat model.Materials and methodsThe right Achilles tendons of 42 healthy female Wistar Albino rats were completely ruptured. The rats were randomly divided into the vitamin C and control groups and both groups included third, tenth and twenty-first day subgroups. One hundred and fifty milligrams (1.5xa0cc) of vitamin C and 1.5xa0cc % 0.9 NaCl were injected once for every 2xa0days for the vitamin C and control groups, respectively. Qualitative and quantitative microscopic comparisons of the repair tissues of both groups were made on the mentioned days.ResultsAngiogenesis was more evident on the third day in the vitamin C group. There was a significant difference between the control and vitamin C groups regarding the type I collagen production on the tenth day. The structure of the repair tissue was almost in the form of regular dense connective tissue at the end of twenty-first day in the vitamin C group. Mean collagen fiber diameter was considerably higher, and the number of active fibroblasts in the repair tissue was slightly elevated in the vitamin C group during the entire healing process.ConclusionHigh-dose vitamin C supplementation once for every 2xa0days has stimulating effects on the Achilles tendon healing because of early angiogenesis and increased collagen synthesis in a healthy rat model. Further studies are needed to make clear the mentioned encouraging effects of the vitamin C on the Achilles tendon healing.

The effect of allopurinol on Na+K+ATPase related lipid peroxidation in ischemic and reperfused rabbit kidney

1. Na+K+ATPase is a membrane bound enzyme whose activity is essential for maintenance of cell viability. Lipid peroxidation changes membrane fluidity and enzyme activity. 2. The purpose of this study was to investigate the effect of allopurinol (free radical scavenger) on Na+K+ATPase activity in rabbit kidney cortex membrane. In this in vivo study we created ischemia and reperfusion in rabbit kidneys. 3. Enzyme activity were low in ischemic and reperfused kidneys, compared to the controls. In allopurinol treated ischemic and reperfused groups, the levels of Na+K+ATPase activity were high compared to the untreated group. 4. It has been concluded that allopurinol may protect this enzyme activity.

The effects of nitric oxide synthesis on the Na+ ,K(+)-ATPase activity in guinea pig kidney exposed to lipopolysaccharides.

Endotoxins (lipopolysaccharides; LPS) are known to cause multiple organ failure, including renal dysfunction. LPS triggers the synthesis and release of cytokines and the vasodilatör nitric oxide (NO•). A major contributor to the increase in NO• production is LPS-stimulated expression of inducible nitric oxide synthase (iNOS). This occurs in vasculature and most organs including the kidney. During endotoxemia, NO• and superoxide react spontaneously to form the potent and versatile oxidant peroxynitrite (ONOO−) and the formation of 3-nitrotyrosine (nTyr)-protein adducts is a reliable biomarker of ONOO− generation. Therefore, the present study was aimed at investigating the role of endogenous nitric oxide in regulating Na+,K+-ATPase activity in the kidney, and at investigating the possible contribution of reactive nitrogen species (RNS) by measuring of iNOS activity. In addition, the present study was aimed at investigating the relationship between nTyr formation with iNOS and Na+,K+-ATPase activities. Previously in our study, nTyr was not detectable in kidney of normal control animals but was detected markedly in LPS exposed animals. In this study, kidney Na+,K+-ATPase activity were maximally inhibited 6 h after LPS injection (P:0.000) and LPS treatment significantly increased iNOS activity of kidney (P:0.000). The regression analysis revealed a very close correlation between Na+,K+-ATPase activity and nTyr levels of LPS treated animals (r = −0.868, P = 0.001). Na+,K+-ATPase activity were also negatively correlated with iNOS activity (r = −0.877, P = 0.001) in inflamed kidney. These data suggest that NO• and ONOO− contribute to the development of oxidant injury. Furthermore, the source of NO• may be iNOS. iNOS are expressed by the kidney, and their activity may increase following LPS administration. In addition, NO• and ONOO− formation inhibited Na+,K+-ATPase activity. This results also have strongly suggested that bacterial LPS disturbs activity of membrane Na+,K+-ATPase that may be an important component leading to the pathological consequences such as renal dysfunction in which the production of RNS are increased as in the case of LPS challenge. (Mol Cell Biochem 271: 107–112, 2005)

Impaired Na + ,K + -ATPase activity as a mechanism of reactive nitrogen species-induced cytotoxicity in guinea pig liver exposed to lipopolysaccharides

In animal models of endotoxin, the excess production of NO and the reactive nitrogen species (RNS), are potent oxidant and nitrating agents, lead to lipid peroxidation, apoptosis, tissue dysfunction and injury and inactivate enzymes in many cell types. Although liver functions are well known to deteriorate following bacterial infection, the underlying specific mechanism(s) remain a matter of considerable debate. Therefore, the aim of the present study was to determine the in vivo effect of bacterial lipopolysaccharides (LPS) on Na+,K+-ATPase activity of guinea pig liver, and to investigate the possible contribution of RNS by measuring of iNOS activity and 3-nitrotyrosine (nTyr) levels. Liver Na+,K+-ATPase activity were maximally inhibited 6 h after LPS injection (p < 0.001). nTyr was not detectable in liver of normal control animals, but was detected markedly in LPS exposed animals. LPS treatment significantly increased iNOS activity of liver (p < 0.001). The regression analysis revealed a very close correlation between Na+,K+-ATPase activity and nTyr levels of LPS treated animals (r = −0.863, p < 0.001). Na+, K+-ATPase activity were also negatively correlated with iNOS activity (r = −0.823, p < 0.003) in inflamed tissues. Our results have strongly suggested that bacterial LPS disturbs activity of membrane Na+,K+-ATPase that may be an important component leading to the pathological consequences such as hepatocyte cell loss and dysfunction in which the production of RNS are increased as in the case of LPS challenge.

Changes in zinc levels and superoxide dismutase activities in the skin of acute, ultraviolet-B-irradiated mice after treatment with ginkgo biloba extract.

Acute ultraviolet-B (UV-B) irradiation is known to act as an initiator in the formation of reactive oxygen species. These oxygen products are highly reactive and they are able to cause irreversible damage to cellular components. Oxygen free radicals are normally neutralized by very efficient systems in the body. These include antioxidant enzymes like superoxide dismutase (SOD). In a healthy subject, there is a balance between free radicals and the levels of antioxidants. In some pathological conditions such as oxidative stress, the level of antioxidants is significantly reduced. The skin contains relatively high levels of zinc (Zn), an essential element known to be a cofactor in some metabolic pathways. Zinc has also been reported to have antioxidant properties.In the present study, we investigated the effect of ginkgo biloba extract (Gbe), a potent free-radical scavenger, on UV-B-irradiated skin by measuring SOD activity and Zn levels in the skin, before and after treatment. The SOD activity was decreased after UV-B exposure, in comparison with the control group (p<0.05). After Gbe treatment, the SOD activity increased (p<0.05) as compared with the untreated UV-B irradiated group. The Zn levels changed in the same pattern as the SOD activity values.

Protective effect of taurine on respiratory burst activity of polymorphonuclear leukocytes in endotoxemia.

Summary.The aim of this study was to evaluate the effect of endotoxin on PMN leukocyte respiratory burst activity by measuring G6PD, NADPH oxidase and XO activities in guinea pig. In addition, the possible protective role of taurine against endotoxin-mediated PMN leukocyte function was examined. All experiments were performed with four groups (control, taurine, endotoxemia, taurine plus endotoxin) of ten guinea pigs. After the endotoxin was administrated (4u2009mg/kg) both G6PD and NADPH oxidase activities were significantly reduced compared with the control group. NADPH oxidase activity returned to the control value and G6PD activity also increased but it did not reach the control value. However when taurine was administrated (300u2009mg/kg) the activity of NADPH oxidase reached the control value; furthermore, G6PD activity also increased but it could not reach to the control value. When taurine was administrated alone, no effect on these enzymes was observed. Following the endotoxin administration, the activity of XO considerably increased. When taurine was administrated together with endotoxine and alone, this activity decreased compared to control value in both conditions. These results indicate that the O2•− formation in PMN leukocytes after the endotoxin administration is ensured by the catalysis of XO due to the inhibited NADPH oxidase activity. It was observed that taurine has considerable anti-inflammatory and antioxidant effects. However, conflicting results were obtained when taurine was administrated alone or together with an oxidant agent.