The effects of iloprost and vitamin C on kidney as a remote organ after ischemia/reperfusion of lower extremities

Effect of Ascorbic Acid on Cardiac Surgery-Associated Acute Kidney Injury Incidence

Objectives  Acute kidney injury (AKI) is associated with higher perioperative mortality and morbidity. Oxidative stress has been proposed as a cause of postoperative AKI. Ascorbic acid (AA) supplementation was suggested as a novel and promising antioxidant. The aim of this study was to evaluate the capability of AA to reduce the incidence of postoperative AKI in cardiac surgery patients.

Methods  A prospective randomized trial was conducted in patients scheduled for on-pump cardiac surgery. Subjects in the AA group received 2 g of AA intravenously during the induction of anesthesia, 2 g before aortic cross-clamp removal and 1 g every 8 hours for five postoperative days (the JERICA protocol). Postoperatively, the patients were monitored for AKI and other complications. Malondialdehyde levels were monitored in a subpopulation of 100 patients to evaluate the effect of AA on oxidative stress level.

Results  The AA and control group consisted of 163 and 169 patients, respectively. The groups were well matched for baseline demographics and had similar intraoperative characteristics. The incidence of AKI in the AA and control group was 20.9 and 28.4%, respectively ( p  = 0.127). The estimated glomerular filtration rate did not differ between the study groups in the entire postoperative period. There was a trend toward higher malondialdehyde values with statistical significance on postoperative day 1 and lower in-hospital mortality in the AA group (0.6 vs. 4.1%, p  = 0.067).

Conclusion  Our results do not support the effectiveness of AA supplementation in reducing the incidence of postoperative AKI in on-pump cardiac surgery patients.

Clinical Registration Number  This study was registered with the ISRCTN Registry under the trial registration number ISRCTN98572043.

Effects of Prostaglandin Analogue Iloprost Treatment on Distant Organ Damage Following Ovarian Ischemia/Reperfusion Injury in Rats: An Experimental Study

Background

Ischemia/reperfusion (I/R) injury causes oxidative stress, which, in turn, may impair the oxidant/antioxidant balance in tissues and cause damage to the tissues. The local effects of I/R injury can be typically observed in the related organ while systemic effects can be observed predominantly in the heart, brain, lung, and kidney. In this study, we aimed to evaluate the effects of iloprost on heart tissues after an ovarian I/R injury in an experimental rat model.

Materials and methods

A total of 32 female Sprague Dawley rats were used for the experiment. The rats were divided into four groups with eight rats each: Group I, control group; Group II, ischemia group; Group III, I/R group; Group IV, I/R + iloprost group. Surgical intervention was performed in each group and after the procedures, heart tissues were obtained and examined histopathologically.

Results

No significant pathological finding was found in Group I and II while degeneration of muscle fibers and interstitial edema was observed in group III and dilation of the vessels was detected in Group IV. No fibrosis or inflammation was observed in any group.

Conclusion

Iloprost provided protection against I/R injury and thus may be an alternative treatment for I/R injury.

Effect of microRNA-26a on vascular endothelial cell injury caused by lower extremity ischemia-reperfusion injury through the AMPK pathway by targeting PFKFB3

Vascular endothelial cell (VEC) dysfunction plays an important role in the ischemia-reperfusion injury (IRI)-related diseases, and microRNAs (miRNAs) are key factors during this process. We conducted this study to investigate whether miRNA-26a (miR-26a) has effect on the IRI-induced VEC injury via the AMPK pathway by targeting 6-phosphofructo-2-kinase-fructose-2,6-biphosphatase 3 (PFKFB3). IRI rat models were successfully constructed by an abdominal incision. Additionally, the cultured VECs were further treated with miR-26a mimic or inhibitor, and si-PFKFB3. Both the reverse-transcription quantitative polymerase chain reaction and the western blot assay method were carried out to examine the expressions of PFKFB3, endothelial nitric oxide synthase (eNOS), and 5'-adenosine monophosphate-activated protein kinase (AMPK) α1, as well as the extent of the AMPK α1 phosphorylation levels in vascular tissues. Circulating endothelial cell (CEC), von Willebrand factor (VWF), thrombomodulin (TM), superoxide dismutase (SOD), malondialdehyde (MDA), nitric oxide (NO), and endothelin (ET) were all measured. In the rat model of an IRI, a poorly expressed miR-26a and contrarily highly expressed PFKFB3 were identified in vascular tissues. In response to an overexpression of miR-26a or to the PFKFB3 gene silencing, decreased CEC number, TM, VWF, MDA, and ET contents, increased AMPK α1, and eNOS levels, as well as the extent of AMPK α1 phosphorylation coordinate with both increased SOD and NO contents based on the restoration of the AMPK pathway. Overexpression of the miR-26a or si-PFKFB3 provides an elevation in cell proliferation. Our study suggests that the miR-26a RNA alleviates lower extremity IRI-induced VEC injury in rats through the activation of the AMPK pathway by inhibiting PFKFB3.

Protective Role for Antioxidants in Acute Kidney Disease

Acute kidney injury causes significant morbidity and mortality in the community and clinic. Various pathologies, including renal and cardiovascular disease, traumatic injury/rhabdomyolysis, sepsis, and nephrotoxicity, that cause acute kidney injury (AKI), induce general or regional decreases in renal blood flow. The ensuing renal hypoxia and ischemia promotes the formation of reactive oxygen species (ROS) such as superoxide radical anions, peroxides, and hydroxyl radicals, that can oxidatively damage biomolecules and membranes, and affect organelle function and induce renal tubule cell injury, inflammation, and vascular dysfunction. Acute kidney injury is associated with increased oxidative damage, and various endogenous and synthetic antioxidants that mitigate source and derived oxidants are beneficial in cell-based and animal studies. However, the benefit of synthetic antioxidant supplementation in human acute kidney injury and renal disease remains to be realized. The endogenous low-molecular weight, non-proteinaceous antioxidant, ascorbate (vitamin C), is a promising therapeutic in human renal injury in critical illness and nephrotoxicity. Ascorbate may exert significant protection by reducing reactive oxygen species and renal oxidative damage via its antioxidant activity, and/or by its non-antioxidant functions in maintaining hydroxylase and monooxygenase enzymes, and endothelium and vascular function. Ascorbate supplementation may be particularly important in renal injury patients with low vitamin C status.

Iloprost as an acute kidney injury-triggering agent in severely atherosclerotic patients

Background

Iloprost, a stable prostacyclin analog, is used as a rescue therapy for severe peripheral arterial disease (PAD). It has systemic vasodilatory and anti-aggregant effects, with severe vasodilatation potentially causing organ ischaemia when severe atherosclerosis is the underlying cause. In this study, we retrospectively analysed renal outcomes after iloprost infusion therapy in 86 patients.

Methods

Eighty-six patients with PAD who received iloprost infusion therapy were retrospectively analysed. Clinical and biochemical parameters were recorded before (initial, Cr1), during (third day, Cr2), and after (14th day following the termination of infusion therapy, Cr3) treatment. Acute kidney injury (AKI) was defined according to KDIGO guidelines as a ≥ 0.3 mg/dl (26.52 μmol/l) increase in creatinine levels from baseline within 48 hours.

Results:

Cr2 (1.46 ± 0.1 mg/dl) (129.06 ± 8.84 μmol/l) and Cr3 (1.53 ± 0.12 mg/dl) (135.25 ± 10.61 μmol/l) creatinine levels were significantly higher compared to the initial value (1.15 ± 0.6 mg/dl) (101.66 ± 53.04 μmol/l). AKI was observed in 36 patients (41.86%) on the third day of iloprost infusion. Logistic regression analysis revealed smoking and not using acetylsalicylic acid as primary predictors (p = 0.02 and p = 0.008, respectively) of AKI during iloprost treatment. On the third infusion day, patients’ urinary output significantly increased (1813.30 ± 1123.46 vs 1545.17 ± 873.00 cm³) and diastolic blood pressure significantly decreased (70.07 ± 15.50 vs 74.14 ± 9.42 mmHg) from their initial values.

Conclusion

While iloprost treatment is effective in patients with PAD who are not suitable for surgery, severe systemic vasodilatation can cause renal ischaemia, resulting in nonoliguric AKI. Smoking, no acetylsalicylic acid use, and lower diastolic blood pressure are the clinical risk factors for AKI during iloprost treatment.

VEGF released from a fibrin biomatrix increases VEGFR-2 expression and improves early outcome after ischaemia-reperfusion injury

Skeletal ischaemia-reperfusion (I-R) injury may influence patient outcome after severe vascular trauma or clamping of major vessels. The aim of this study was to observe whether locally applied vascular endothelial growth factor (VEGF) in fibrin could induce the expression of VEGF-receptor-2 (VEGFR-2) and improve the outcome after I-R injury. Transgenic mice expressing VEGFR-2 promoter-controlled luciferase were used for the assessment of VEGFR-2 expression. Ischaemia was induced for 2 h by a tension-controlled tourniquet to the hind limb, followed by 24 h of reperfusion. The animals were locally injected subcutaneously with fibrin sealant containing 20 or 200 ng VEGF; control animals received no treatment or fibrin sealant application. In vivo VEGFR-2 expression was quantified upon administration of luciferin at several observation times. For oedema and inflammation quantification, wet:dry ratio measurements and a myeloperoxidase assay of the muscle tissue were performed. Laser Doppler imaging showed that ischaemia was present and that the blood flow had returned to baseline levels after 24 h of reperfusion. VEGFR-2 expression levels in the fibrin + 200 ng VEGF were significantly higher than in all other groups. Granulocyte infiltration was reduced in both treatment groups, as well as reduced oedema formation. These results showed that VEGF released from fibrin had a positive effect on early I-R outcome in a mouse model, possibly via VEGFR-2. Copyright © 2016 John Wiley & Sons, Ltd.

The effect of iloprost and N-acetylcysteine on skeletal muscle injury in an acute aortic ischemia-reperfusion model: an experimental study

Objective. The objective of this study was to examine the effects of iloprost and N-acetylcysteine (NAC) on ischemia-reperfusion (IR) injuries to the gastrocnemius muscle, following the occlusion-reperfusion period in the abdominal aorta of rats. Materials and Methods. Forty male Sprague-Dawley rats were randomly divided into four equal groups. Group 1: control group. Group 2 (IR): aorta was occluded. The clamp was removed after 1 hour of ischemia. Blood samples and muscle tissue specimens were collected following a 2-hour reperfusion period. Group 3 (IR + iloprost): during a 1-hour ischemia period, iloprost infusion was initiated from the jugular catheter. During a 2-hour reperfusion period, the iloprost infusion continued. Group 4 (IR + NAC): similar to the iloprost group. Findings. The mean total oxidant status, CK, and LDH levels were highest in Group 2 and lowest in Group 1. The levels of these parameters in Group 3 and Group 4 were lower compared to Group 2 and higher compared to Group 1 (P < 0.05). The histopathological examination showed that Group 3 and Group 4, compared to Group 2, had preserved appearance with respect to hemorrhage, necrosis, loss of nuclei, infiltration, and similar parameters. Conclusion. Iloprost and NAC are effective against ischemia-reperfusion injury and decrease ischemia-related tissue injury.

Hydrogen sulfide reduces inflammation following abdominal aortic occlusion in rats

BACKGROUND

Remote renal ischemia-reperfusion injury (IRI) following infra-renal aortic occlusion leads to acute kidney injury and systemic inflammation. Hydrogen sulfide is a mediator of IRI and can ameliorate tissue injury in many organ systems. Its role in vascular surgery has yet to be established. We assessed the role of hydrogen sulfide in a rodent model of aortic occlusion.

METHODS

Wistar rats were divided into sham, control, and treatment groups (n = 6). Inflammation was assessed using a nonrecovery protocol. The infra-renal aorta was cross-clamped for 60 min and animals were reperfused for 120 min. Ten minutes before clamp release, treatment animals received hydrogen sulfide (10, 30, or 50 μg/kg) and control animals received 0.9% saline injected into the retroperitoneum. Renal injury and histology were assessed by a recovery protocol. The procedure was identical to the nonrecovery arm but with a single dose of hydrogen sulfide (30 μg/kg) and animals were recovered for 7 days.

RESULTS

There was no difference in animal weight between the groups (P = 0.337). In the nonrecovery arm, there was a reduction in serum levels of tumor necrosis factor alpha in sulfide-treated animals compared with controls (909 ± 98 vs. 607 ± 159 pg/mL; P = 0.0038). There was also a reduction in myeloperoxidase-positive cells in renal tissue in the sulfide-treated animals compared with controls (8 ± 4 vs. 17 ± 9; P = 0.03). There was no difference in histological injury score or endothelin-1 levels. In the recovery arm, there was no difference in renal function, Kidney Injury Molecule-1 levels, or histological injury scores.

CONCLUSION

Hydrogen sulfide has systemic and renal anti-inflammatory effects in remote IRI following aortic occlusion in rats.

Protective effect of N-acetylcysteine on kidney as a remote organ after skeletal muscle ischemia-reperfusion

PURPOSE: To investigate whether N-acetylcysteine has a protective effect against renal injury as a remote organ after skeletal muscle ischemia-reperfusion in rats. METHODS: Twenty Wistar male rats were divided randomly into two experimental groups: group ischemia-reperfusion (group I) and group ischemia-reperfusion + N-acetylcysteine (group II). After ketamine and xylazine anesthesia, femoral artery was exposed. All animals were undergone 2h of ischemia by occlusion femoral artery and 24h of reperfusion. Rats that were treated with N-acetylcysteine given IV at a dose of 150 mg/kg-¹, immediately before reperfusion. After 24h of reperfusion, the blood samples were collected and submitted for evaluation of plasmatic urea, creatinine values and then rats were euthanized and left kidney harvested for histopathological analysis under light microscopy. RESULTS: The urea (35±7.84 mg.dL-1), creatinine (1.46±0.47 mg.dL-1) values were significantly lower in group II (P=0.000). Renal histopathologic study in group I showed extensive distal and proximal tubular cells necrosis and sloughing of epithelial cells into the tubular lumen, cast formation in tubule and glomerul, glomerul fibrosis and hemorrhage. Histopathologically, there was a significant difference (p=0.037) between two groups. CONCLUSION: The N-acetylcysteine was able to decrease renal injury induced by skeletal muscle ischemia reperfusion in rats.

The effect of phlebotomy and mannitol on acute renal injury induced by ischemia/reperfusion of lower limbs in rats

BACKGROUND

Abdominal aortic surgery can cause ischemic/reperfusion (I/R) injury not only in the lower limbs but also in remote organs such as kidneys. Venous blood volume exclusion from the inferior vena cava (phlebotomy) or/and mannitol are used as a treatment for I/R injury of kidney in humans, despite the fact that the effectiveness of these treatments is still debated. The aim of this study was to evaluate the effects of phlebotomy or/and mannitol on rat kidneys in a model of lower limbs I/R-induced acute renal injury (ARI).

MATERIAL AND METHODS

Thirty male Wistar albino rats were used and divided into five groups: (I) sham-operated group, laparotomy without I/R injury (group [S], n = 6); (II) I/R group, infrarenal aortic cross-clamp was used for lower limbs I/R, 3 hours of ischemia followed by 2 hours of reperfusion (group [I/R], n = 6); (III) I/R + phlebotomy group, identical to group [I/R] except for 1 mL of blood aspiration from the inferior caval vein just after ischemia (group [P], n = 6); (IV) I/R + mannitol-treated group, these rats were subjected to I/R and received a bolus injection of mannitol (group [M], n = 6); and (V) I/R + phlebotomy + mannitol-treated group (group [P + M], n = 6), the same procedures were performed as those described for previous groups. At the end of 2-hour reperfusion, all rats were sacrificed. Both kidneys were harvested for biochemical assay (myeloperoxidase [MPO] and superoxide dismutase [SOD] activities, and malondialdehyde [MDA] and reduced glutathione levels) and for histopathological examination (tubular necrosis and acute inflammation on kidney [ARI score]).

RESULTS

Aortic I/R significantly increased the level of MDA (reflecting lipid peroxidation), SOD (enzymatic endogenous antioxidant), and MPO (reflecting neutrophil infiltration) activity (p < 0.05). Phlebotomy or/and mannitol treatments significantly decreased the level of MDA, SOD, and MPO activity and increased glutathione level (nonenzymatic antioxidant in the kidney tissues) (p < 0.05). Histological evaluation of ARI score showed that aortic I/R significantly increased (p value for group [S] versus group [I/R] was 0.012), whereas phlebotomy or/and mannitol treatments significantly decreased tubular necrosis and inflammatory infiltration (p values for group [I/R] versus group [P], [M], and [P + M] were 0.043, 0.043, and 0.003, respectively).

CONCLUSION

This experiment clearly indicated that the lower limbs I/R-induced ARI attenuated significantly by phlebotomy or/and mannitol treatments. Phlebotomy plus mannitol is more effective treatment than phlebotomy or mannitol alone in preventing lower limbs I/R-induced ARI in rats. Further clinical studies are required to clarify whether phlebotomy or/and mannitol treatments are beneficial in alleviating of ARI during abdominal aortic surgery.

Affirmative effects of iloprost on apoptosis during ischemia-reperfusion injury in kidney as a distant organ

OBJECTIVE

Apoptosis and its regulatory mechanisms take part in renal ischemia-reperfusion (I/R) injury which can result in acute renal failure and the inhibition of the caspase is considered as a new therapeutic strategy. In this context, we investigated the antiapoptotic and cytoprotective effects of iloprost, a prostacyclin analog, in kidney as a distant organ.

METHODS

Wistar albino rats were randomized into five groups (n = 12 in each) as sham, ischemia, I/R, iloprost (10 μg kg(-1)), and I/R + iloprost (10 μg kg(-1)). A 4 h reperfusion procedure was carried out after 4 h of ischemia. Caspase-8 was evaluated for death receptor-induced pathways, whereas caspase-9 was evaluated for mitochondria-dependent pathways and caspase-3 was investigated for overall apoptosis. Superoxide dismutase (SOD) enzyme activity and nitrite content as an indicator of nitric oxide (NO) production were also analyzed in kidney tissues.

RESULTS

Caspases-3, -8, and -9 were all significantly elevated in both ischemia and I/R groups compared to the sham group; however, treatment with iloprost reduced caspases-3, -8, and -9. SOD enzyme activity was attenuated by iloprost when compared to ischemic rats. The different effects of NO were found which change according to the present situation in ischemia, I/R, and treatment with iloprost.

CONCLUSIONS

These findings suggested that iloprost prevents apoptosis in both receptor-induced and mitochondria-dependent pathways in renal I/R injury and it may be considered as a cytoprotective agent for apoptosis. Understanding the efficiency of iloprost on the pathways for cell death may lead to an opportunity in the therapeutic approach for renal I/R injury.

The use of a prostacyclin analog, iloprost, as an adjunct to uterus preservation with histidine-tryptophan-ketoglutarate solution

INTRODUCTION

Although assisted reproductive techniques have made most causes of both male and female infertility treatable, uterine factor infertility is not able to therapy. Therefore, transplantation of the uterus has been suggested as a future possible cure. Organ preservation solutions seek to reduce reperfusion injury. Since iloprost is an antioxidant with cytoprotective properties, we investigated its potential positive effects in histidine-tryptophan-ketoglutarate (HTK) solution after 4 or 24 h cold storage period of the rat uterus.

METHODS

We divided 24 female Wistar-albino rats into four groups: Group 1 had the uterus tissue stored in HTK solution at 4 °C for 4h. Group 2, the tissue was stored in HTK solution combined with iloprost (10(-8) M) for 4h at 4 °C. The same procedures were repeated for 24 h for Groups 3 and 4 respectively. Tissue levels of malondialdehyde (MDA) and nitric oxide (NO), as indicators of oxidative stress were determined with histopathological evaluations.

RESULTS

MDA and NO levels were compared between the group 1 vs 3; and 2 vs 4. No significant difference was observed between the groups. Cold storage for 24 h produced alterations in histological appearances that were mitigated by the addition of iloprost to HTK solution.

CONCLUSION

In conclusion, addition of iloprost to HTK solution reversed the histological alterations after 24h-cold storage of the rat uterus.

Renoprotective effect of Linum usitatissimum seeds through haemodynamic changes and conservation of antioxidant enzymes in renal ischaemia-reperfusion injury in rats

Objective

To evaluate an ethanolic extract of seeds of Linum usitatissimum (Linn.) (EELU) for its renoprotective role in rats through its antihypertensive effect and conservation of biological oxidation enzymes.

Materials and methods

Male Wistar rats (200–250 g) underwent uninephrectomy on day 0; after 2 weeks of recovery, the nephrectomised rats were divided into four groups of eight each: (I) sham (II); renal ischaemia reperfusion (RIR); (III) RIR + EELU 200 mg/kg; and (IV) RIR + EELU 400 mg/kg. In group II, III and IV the renal artery was occluded for 45 min and reperfused for 4 weeks; the sham group did not undergo RIR.

Results

EELU (400 mg/kg) significantly decreased the haemodynamic changes after 4 weeks of RIR injury. EELU treatment significantly restored the levels of renal endogenous antioxidant enzymes and membrane-bound enzymes. EELU 400 mg/kg restored the levels of blood urea nitrogen and serum creatinine. EELU also decreased the levels of tumour necrosis factor-α and myeloperoxidase activity. A flow-cytometric study confirmed a significant decrease in cellular necrosis and increase in viability after RIR in EELU-treated rats. The anti-apoptotic role of EELU was evident from the decrease in DNA fragmentation. Renal tissue damage as assessed by histopathology was decreased in groups III and IV (200 and 400 mg/kg EELU).

Conclusion

We conclude that EELU protected the kidney against RIR-induced renal injury, probably by inhibiting reactive oxygen species that have a causal role in such cases. It also inhibits apoptotic cell death and inflammation, and improves haemodynamic changes.

ETS-GS, a new antioxidant, ameliorates renal ischemia-reperfusion injury in a rodent model

BACKGROUND

Ischemia-reperfusion (I/R) contributes to acute kidney injury (AKI). On the other hand, anti-oxidative drugs help to prevent renal injury caused by I/R. The current study examined whether a new antioxidant, ETS-GS, inhibits reactive oxygen species (ROS) generation and thereby prevents renal I/R injury in rodent models.

METHODS

Rats with experimentally-induced renal I/R injury were treated concurrently with an intravenous injection of either ETS-GS or saline. Anesthesia was induced with sevoflurane.

RESULTS

Histologic examination revealed marked reduction of interstitial congestion, edema, inflammation, and hemorrhage in kidney tissue harvested 24 h after ETS-GS treatment. Renal I/R-induced secretion of nitric oxide (NO) in serum was inhibited by ETS-GS treatment. Furthermore, malondialdehyde (MDA) levels in the kidney were significantly lower in ETS-GS-treated rats with renal I/R. Moreover, when murine macrophage-like RAW264.7 cells were stimulated with antimycin A in the presence or absence of simultaneous ETS-GS treatment, ETS-GS decreased ROS levels.

CONCLUSIONS

Thus, ETS-GS lowered ROS levels in cultured cells, reduced serum NO levels, decreased renal MDA levels, and protected rats against I/R-induced kidney injury. Given these in vitro and in vivo findings, ETS-GS is a strong candidate for future exploration of therapeutic potential in various human I/R diseases.

The effect of iloprost on renal dysfunction after renal I/R using cystatin C and beta2-microglobulin monitoring

The purpose of this study was to investigate the effect of iloprost, a cytoprotective prostacyclin analog, on renal injury during unilateral renal I/R in rats and to determine whether the levels of serum cystatin C (CyC) and beta2-microglobulin (B2M), as markers of glomerular function, might denote this injury. Thirty-two Wistar rats were randomized into four groups (n = 8) as follows: control (sham laparotomy), renal I/R (60-min left renal ischemia and 120-min reperfusion), renal I/R + iloprost (20 ng kg(-1) min(-1) infusion during renal I/R period, i.v.), and control + iloprost. Blood and kidney tissue samples were obtained for biochemical and histological analysis from all rats. Serum urea, creatinine, CyC, and B2M levels were evaluated for biochemical analysis. Histopathological changes in renal structure were examined for histological analysis. Serum urea, creatinine, and CyC levels were significantly increased in the renal I/R group. Iloprost treatment decreased these three markers in the renal I/R + iloprost group. beta2-Microglobulin levels were not significantly changed in any group. Histological analyses showed that renal I/R elicited significant renal injury, whereas iloprost significantly decreased I/R-induced renal injury. Serum CyC level is one of the good indicators of acute renal damage due to I/R produced by renal artery occlusion. In contrast, we have shown that there are no significant changes in the levels of serum B2M levels that would make it an accurate diagnostic tool for detecting acute changes in renal injury subject to renal I/R in rats.

The protective effects of ascorbic acid against renal ischemia-reperfusion injury in male rats

There is increasing evidence to suggest that toxic oxygen radicals play an essential role in the pathogenesis of ischemia/reperfusion (I/R) injury in the kidney. This study was designed to investigate the effects of ascorbic acid (AA) in I/R-induced renal injury in rats. Thirty two male Sprague-Dawley rats were divided equally into four groups: group 1 (control; dissection of the right renal pedicle without nephrectomy), group 2 (sham operated; unilateral nephrectomy), group 3 (I/R; unilateral nephrectomy + I/R); and group 4 (AA+I/R; unilateral nephrectomy and I/R treated with ascorbic acid, 250mg kg(-1) i.p., for one hour prior to ischemia). On the 15th day following nephrectomy, groups 3 and 4 were subjected to 45 min of renal pedicle occlusion followed by 3 h of reperfusion. At the end of the treatment period, kidney samples were taken for histological examination or determination of the renal malondialdehyde (MDA) and glutathione (GSH) levels. Serum creatinine, blood urea nitrogen (BUN), and lactate dehydrogenase (LDH) concentrations were measured for the evaluation of renal function. I/R caused a significant decrease in GSH level, which was accompanied with a significant increase in MDA level of kidney tissues. Similarly, serum BUN and creatinine levels, as well as LDH, were elevated in the I/R group as compared to the control group. In group four, AA treatment reversed all the changes in these biochemical indices, as well as histopathological alterations normally induced by I/R. The findings imply that reactive oxygen species play a causal role in I/R-induced renal injury, and that AA exerts renoprotective effects, probably by radical scavenging and antioxidant activities.

Vitamin effects on the immune system: vitamins A and D take centre stage

Vitamins are essential constituents of our diet that have long been known to influence the immune system. Vitamins A and D have received particular attention in recent years as these vitamins have been shown to have an unexpected and crucial effect on the immune response. We present and discuss our current understanding of the essential roles of vitamins in modulating a broad range of immune processes, such as lymphocyte activation and proliferation, T-helper-cell differentiation, tissue-specific lymphocyte homing, the production of specific antibody isotypes and regulation of the immune response. Finally, we discuss the clinical potential of vitamin A and D metabolites for modulating tissue-specific immune responses and for preventing and/or treating inflammation and autoimmunity.

Tezosentan reduces the renal injury induced by abdominal aortic ischemia-reperfusion in rats

BACKGROUND

Renal injury induced by aortic ischemia-reperfusion (IR) is an important factor in the development of postoperative acute renal failure following abdominal aortic surgery. Endothelin (ET) is involved in the development of renal injury induced by aortic IR and tezosentan (R0 61-0612) is a specific ET receptor antagonist. The aim of this study was to examine the effect of tezosentan on renal injury induced by abdominal aortic IR in rats.

MATERIAL AND METHODS

Twenty-four Wistar-Albino rats were randomized into three groups (eight per group). Control group underwent laparotomy and dissection of the infrarenal abdominal aorta (IAA) without occlusion. The aortic IR group underwent laparotomy and clamping of the IAA for 120 min followed by 120 min of reperfusion. Aortic IR + tezosentan group underwent same aortic IR periods, and received a bolus intravenous injection of 10 mg/kg tezosentan before ischemia plus continuous intravenous infusion of 1 mg/kg/h tezosentan during 120 min ischemia and 120 min reperfusion. At the end of the experiment, blood and kidney tissue specimens were obtained for biochemical analysis. Histological evaluation of the rat kidney tissues was also done.

RESULTS

Biochemical analysis showed that aortic IR significantly increased (P < 0.05 versus control) while tezosentan significantly decreased (P < 0.05 versus aortic IR) the tissue levels of malondialdehyde, superoxide dismutase, catalase and myeloperoxidase. Histological analyses showed that aortic IR significantly increased (P < 0.05 versus control) while tezosentan significantly decreased (P < 0.05 versus aortic IR) focal glomerular necrosis, dilatation of Bowman's capsule, degeneration of tubular epithelium, necrosis in tubular epithelium and tubular dilatation in the renal tissue samples.

CONCLUSION

The results of this study indicate that tezosentan reduces renal injury induced by aortic IR in rats. We think that tezosentan exerted this beneficial effect via reducing oxidative stress and lipid peroxidation, inhibition of leukocyte infiltration into renal tissue and acting cytoprotective on renal tubular cells after aortic IR.