Protective effect of aminoguanidine against oxidative stress and bladder injury in cyclophosphamide-induced hemorrhagic cystitis in rat

Advanced Glycation End Products in Health and Disease

Advanced glycation end products (AGEs), formed through the nonenzymatic reaction of reducing sugars with the side-chain amino groups of lysine or arginine of proteins, followed by further glycoxidation reactions under oxidative stress conditions, are involved in the onset and exacerbation of a variety of diseases, including diabetes, atherosclerosis, and Alzheimer’s disease (AD) as well as in the secondary stages of traumatic brain injury (TBI). AGEs, in the form of intra- and interprotein crosslinks, deactivate various enzymes, exacerbating disease progression. The interactions of AGEs with the receptors for the AGEs (RAGE) also result in further downstream inflammatory cascade events. The overexpression of RAGE and the AGE-RAGE interactions are especially involved in cases of Alzheimer’s disease and other neurodegenerative diseases, including TBI and amyotrophic lateral sclerosis (ALS). Maillard reactions are also observed in the gut bacterial species. The protein aggregates found in the bacterial species resemble those of AD and Parkinson’s disease (PD), and AGE inhibitors increase the life span of the bacteria. Dietary AGEs alter the gut microbiota composition and elevate plasma glycosylation, thereby leading to systemic proinflammatory effects and endothelial dysfunction. There is emerging interest in developing AGE inhibitor and AGE breaker compounds to treat AGE-mediated pathologies, including diabetes and neurodegenerative diseases. Gut-microbiota-derived enzymes may also function as AGE-breaker biocatalysts. Thus, AGEs have a prominent role in the pathogenesis of various diseases, and the AGE inhibitor and AGE breaker approach may lead to novel therapeutic candidates.

Tropisetron ameliorates cyclophosphamide-induced hemorrhagic cystitis in rats

Hemorrhagic cystitis is one of the most important complications of cyclophosphamide, a drug widely used in cancer chemotherapy and bone marrow transplantation. 5-HT₃ antagonists are anti-emetic agents and have been shown to have notable anti-inflammatory and antioxidant properties. This study was designed to investigate the possible protective effects of tropisetron against cyclophosphamide-induced hemorrhagic cystitis in rats. Hemorrhagic cystitis was induced in female rats by cyclophosphamide (270 mg/kg). Tropisetron (2.5, 5 and 7.5 mg/kg), granisetron (2.5 and 5 mg/kg), and ondansetron (5 mg/kg) were injected 15 min before, 4 and 8 h after cyclophosphamide. To evaluate the role of alpha7 nicotinic acetylcholine receptor (α7nAChR), its antagonist, methyllycaconitine (5 mg/kg) was administered 30 min before tropisetron. After 24 h, animals were killed under anesthesia. Macroscopic and histological changes were evaluated. Malondialdehyde (MDA), glutathione (GSH) and Evans blue were measured spectrophotometrically. Furthermore, the protein levels of p38 mitogen-activated protein kinases (P38 MAPK), p-P38, signal transducer and activator of transcription 3 (STAT3), p-STAT3 and Poly (ADP-ribose) polymerase (PARP) were determined using Western blot. Cyclophosphamide administration significantly induced histopathological damages and increased MDA, p-p38/p38, p-STAT3/STAT3, and PARP levels compared with the saline group. Tropisetron treatment diminished histopathological injuries as well as MDA level, and STAT3 activity compared to cyclophosphamide treated rats. Co-administration of methyllycaconitine with tropisetron, partially or completely reversed the protective effects of tropisetron. Our results showed that prophylactic administration of tropisetron markedly ameliorated the cyclophosphamide-induced bladder hemorrhage and inflammation in rats. These effects of tropisetron were α7nAChR dependent.

Protective effect of Nasturtium officinale R. Br and quercetin against cyclophosphamide-induced hepatotoxicity in rats

Cyclophosphamide (CPA) is used in the management of autoimmune conditions and malignant illnesses. However, its therapeutic use is limited because of its severe side effects, especially hepatotoxicity attributed to oxidative stress. Nasturtium officinale R. Br (watercress or WC) has pharmacological properties, such as anti-inflammation, and antioxidant activities. Therefore, the present study was design to assess effects of WC or its active ingredient, quercetin (QE), against CPA-induced hepatotoxicity. For this study, 49 male Wistar rats (200-250 g) were randomly selected and categorized into seven equal groups. The animals were pre- and post-treated with both hydroalcoholic extract of WC (500 mg/kg) and quercetin (75 mg/kg) for 10 consecutive days, and intraperitoneal administration of CPA (200 mg/kg) was performed on only day 10, one hour before the last dose of WC or quercetin. On day 11, all the animals were sacrificed, and their blood and liver were gathered for evaluation of the liver enzyme, hepatic oxidative stress markers, antioxidant enzymes activity, and hematoxylin and eosin staining. CPA significantly increased malondialdehyde (MDA), protein carbonyl (PCO) and nitric oxide (NO) levels and liver biomarkers. Otherwise, hepatic catalase (CAT), reduced glutathione (GSH), total thiol content (tSH), and ferric reducing antioxidant power (FRAP) were considerably lower than the control group. Results showed that WC has the ability to reduce the changes (MDA, PCO, FRAP, CAT, ALT and AST) and QE (MDA, PCO, AST) induced by CPA (p < 0.05). Histopathological finding confirmed the indicated results. These findings propose that WC and QE have protective effect against the CPA-induced hepatotoxicity by decreasing oxidative stress.

Aminoguanidine Protects Boar Spermatozoa against the Deleterious Effects of Oxidative Stress

Aminoguanidine is a selective inhibitor of the inducible nitric oxide synthase (iNOS) and a scavenger of reactive oxygen species (ROS). Numerous studies have shown the antioxidant properties of aminoguanidine in several cell lines, but the in vitro effects of this compound on spermatozoa under oxidative stress are unknown. In this study, we tested the hypothesis that aminoguanidine may protect against the detrimental effects of oxidative stress in boar spermatozoa. For this purpose, sperm samples were incubated with a ROS generating system (Fe²⁺/ascorbate) with or without aminoguanidine supplementation (10, 1, and 0.1 mM). Our results show that aminoguanidine has powerful antioxidant capacity and protects boar spermatozoa against the deleterious effects of oxidative stress. After 2 h and 3.5 h of sperm incubation, the samples treated with aminoguanidine showed a significant increase in sperm velocity, plasma membrane and acrosome integrity together with a reduced lipid peroxidation in comparison with control samples (p < 0.001). Interestingly, except for the levels of malondialdehyde, the samples treated with 1 mM aminoguanidine did not differ or showed better performance than control samples without Fe²⁺/ascorbate. The results from this study provide new insights into the application of aminoguanidine as an in vitro therapeutic agent against the detrimental effects of oxidative stress in semen samples.

Alleviation of Cyclophosphamide-induced Hemorrhagic Cystitis by Dietary Pomegranate: A Comparative Experimental Study With Mesna

In this study, we investigated the effects of pomegranate on alleviating cyclophosphamide-induced hemorrhagic cystitis (HC). Initially, 16 Sprague-Dawley rats were allocated into 4 groups: group 1 (control), group 2 (CP) in which HC was induced by cyclophosphamide; group 3 (CP+M), HC-induced rats that received Mesna regimen, and group 4 (CP+P), which compromised rats that had been on a 14-day diet of pomegranate juice before HC induction. Cystometry was performed a few hours before euthanasia; after euthanasia, aortic blood samples and bladder tissue samples were obtained to perform TUNEL assay, and histopathologic and biochemical assessments. Urodynamic findings revealed that mean detrusor pressure in CP+P was significantly lower compared with that in CP and CP+M (P<0.05). Histopathologically, urothelium destruction and inflammation were lower in CP+P and CP+M compared with that in CP. Collagen destruction was less prominent in CP+P compared with that in CP and CP+M. Tissue and plasma levels of malondialdehyde were significantly lower in CP+P versus CP (P<0.05). Catalase activity and total protein thiol group levels in plasma and bladder tissue were higher in CP+P versus CP (P<0.05). The TUNEL positivity in CP+P was significantly weaker than that in CP, indicating less DNA fragmentation and apoptosis. Pomegranate's characteristics could significantly affect the inflammatory and destructive process of hemorrhagic cystitis.

Aminoguanidine pretreatment prevents methotrexate-induced small intestinal injury in the rat by attenuating nitrosative stress and restoring the activities of vital mitochondrial enzymes

BACKGROUND

One of the major toxic side effects of methotrexate (MTX) is enterocolitis, for which there is no efficient standard treatment. Nitric oxide overproduction has been reported to play an important role in MTX-induced mucositis. This study was designed to investigate whether pretreatment with aminoguanidine (AG) - a selective iNOS inhibitor - prevents MTX-induced mucositis in rats.

METHODS

Rats were pretreated with AG (30 and 50 mg/kg body weight) i.p. daily 1 h before MTX (7 mg/kg body weight) administration for 3 consecutive days. After the final dose of MTX, the rats were killed, and the small intestines were used for analysis.

RESULTS

The small intestines of MTX-treated rats showed moderate to severe injury. Pretreatment with AG had a dose-dependent protective effect on MTX-induced mucositis. AG pretreatment reduced iNOS protein levels, mucosal nitric oxide levels, and protein tyrosine nitration. AG pretreatment also restored the activities of electron transport chain (ETC) complexes, vital tricarboxylic acid (TCA cycle) enzymes, and mitochondrial antioxidant enzymes.

CONCLUSIONS

These findings suggest that AG is beneficial in ameliorating MTX-induced enteritis in rats.

Aminoguanidine treatment increased NOX2 response in diabetic rats: Improved phagocytosis and killing of Candida albicans by neutrophils

In this study, we show that aminoguanidine (AMG), an inhibitor of protein glycation, increases the NOX2 (phagocyte NADPH oxidase) response and microbicidal activity by neutrophils, regardless of diabetic status. The non-enzymatic glycation of proteins, yielding irreversible advanced glycation end products (AGEs), is involved in the development of diabetes complications, including alterations of signaling pathways and the generation of reactive oxygen species by phagocytes. The phagocytes produce ROS (reactive oxygen species) through activation of the NOX2 complex, which generates superoxide. The purpose of this study was to evaluate the effect of hyperglycemia and the glycation of proteins on the NOX2 activity of neutrophils and its implications for cellular physiology, with a focus on the microbicidal activity of these cells. We treated diabetic rats with AMG and evaluated neutrophil ROS generation and Candida albicans killing ability. We observed a large increase in the microbicidal activity of peritoneal neutrophils from AMG-treated rats. The increase was independent of diabetic status and myeloperoxidase activity. Collectively, our results suggest that AMG has an immunomodulator role that triggers an increase in the microbicidal response of neutrophils mainly related to reactive oxygen species production by NOX2.

Ketamine-induced ulcerative cystitis and bladder apoptosis involve oxidative stress mediated by mitochondria and the endoplasmic reticulum

Ketamine abusers develop severe lower urinary tract symptoms. The major aims of the present study were to elucidate ketamine-induced ulcerative cystitis and bladder apoptosis in association with oxidative stress mediated by mitochondria and the endoplasmic reticulum (ER). Sprague-Dawley rats were distributed into three different groups, which received normal saline or ketamine for a period of 14 or 28 days, respectively. Double-labeled immunofluorescence experiments were performed to investigate tight junction proteins for urothelial barrier functions. A TUNEL assay was performed to evaluate the distribution of apoptotic cells. Western blot analysis was carried out to examine the expressions of urothelial tight junction proteins, ER stress markers, and apoptosis-associated proteins. Antioxidant enzymes, including SOD and catalase, were investigated by real-time PCR and immunofluorescence experiments. Ketamine-treated rats were found to display bladder hyperactivity. This bladder dysfunction was accompanied by disruptions of epithelial cadherin- and tight junction-associated proteins as well as increases in the expressions of apoptosis-associated proteins, which displayed features of mitochondria-dependent apoptotic signals and ER stress markers. Meanwhile, expressions of mitochondria respiratory subunit enzymes were significantly increased in ketamine-treated bladders. Conversely, mRNA expressions of the antioxidant enzymes Mn-SOD (SOD2), Cu/Zn-SOD (SOD1), and catalase were decreased after 28 days of ketamine treatment. These results demonstrate that ketamine enhanced the generation of oxidative stress mediated by mitochondria- and ER-dependent pathways and consequently contributed to bladder apoptosis and urothelial lining defects. Such oxidative stress-enhanced bladder cell apoptosis and urothelial barrier defects are potential factors that may play a crucial role in bladder overactivity and ulceration.

Intravesical hyaluronic acid treatment improves bacterial cystitis and reduces cystitis-induced hypercontractility in rats

OBJECTIVE

To investigate the effect of intravesical hyaluronic acid on Escherichia coli-induced cystitis and cystitis-induced hypercontractility in rats.

METHODS

Bacterial cystitis was induced in Wistar female rats by intravesical inoculation of E. coli. Isotonic saline was instilled in the control group (n = 6). The rats were either non-treated, treated with gentamycin (4 mg/kg, 5 days) or treated intravesically with hyaluronic acid (0.5 mL, 0.5%). On the eighth day, the bladder tissues were excised for histological examination, and the measurements of myeloperoxidase, superoxide dismutase and catalase activities. Contraction/relaxation responses to carbachol, isoprotrenol and papaverine were studied.

RESULTS

Tissue myeloperoxidase activity was increased, but superoxide dismutase and catalase activities were decreased in bacterial cystitis, while hyaluronic acid treatment reversed these changes. In the hyaluronic acid-treated group, healing of the uroepithelium was observed, while decreased inflammatory cell infiltration was obvious in gentamycin-treated group. E. coli-induced cystitis in all rats resulted in increased contraction responses to carbachol compared with controls (P < 0.01). Treatment with hyaluronic acid, but not gentamycin, significantly (P < 0.05) depressed hypercontractility at maximum carbachol concentrations. In all rats with cystitis, papaverine-induced relaxation was increased, whereas isoproterenol-induced relaxation curves were not different between the studied groups.

CONCLUSION

Gentamycin treatment, despite its ameliorative effect on inflammation, had no impact on the contractile dysfunction of the injured bladder. Intravesical hyaluronic acid, in addition to its supportive role in the healing of the epithelium, seems to lower the increased threshold for contraction and to reduce oxidative stress. These findings support a potential role for hyaluronic acid in the treatment of bacterial cystitis.

Effects of aminoguanidine and melatonin on intestinal ischemia/reperfusion injury in rats: An assessor-blinded, controlled experimental study

BACKGROUND

The reactive oxygen and nitrogen species generated during reperfusion of tissue are characteristic of intestinal ischemia and reperfusion (IIR) injury.

OBJECTIVE

This study was designed to assess whether the administration of aminoguanidine (AG), a selective nitric oxide synthase inhibitor, and/or melatonin has protective potential in IIR injury.

METHODS

Male Wistar albino rats (age, 3-4 weeks; weight, 100-150 g) were divided in a nonrandom fashion into 5 groups of equal size: group 1, IIR injury + AG 100 mg/kg; group 2, IIR injury + melatonin 10 mg/kg; group 3, IIR injury + AG 100 mg/kg + melatonin 10 mg/kg; group 4, sham operation; and group 5, IIR injury alone. Sixty minutes of intestinal ischemia and 4 hours of reperfusion were carried out in all but the sham-operation group. Ileal specimens were obtained from all rats to determine the extent of histologic changes, measure tissue concentrations of malondialdehyde (MDA) and protein carbonyl (PC), and assess the activity of superoxide dismutase (SOD) and glutathione peroxidase (GPx). Specimens were also assessed and scored by a pathologist blinded to the experiment and the data.

RESULTS

Forty rats were divided into 5 groups of 8 each; all 40 survived until study end. In the IIR injury-alone group, mean (SD) MDA concentration and PC content were significantly higher than that of the sham-operation group, and SOD and GPx activity were significantly lower: MDA concentration, 0.86 (0.03) versus 0.54 (0.01) mmol/g protein, respectively; PC content, 0.60 (0.02) versus 0.34 (0.01) mmol/g protein; SOD activity, 104.33 (43.14) versus 2954.72 (109.55) U/g protein; and GPx activity, 10.44 (0.63) versus 24.34 (1.77) U/g protein (all, P < 0.001). Administration of AG, melatonin, and the AG/melatonin combination was associated with significantly higher SOD (1802.31 [102.35], 1776.50 [58.41], and 1924.28 [98.10] U/g protein, respectively) and GPx (17.36 [1.23], 15.96 [1.08], and 18.06 [1.72] U/g protein) activity and significantly lower MDA concentration (0.62 [0.02], 0.64 [0.02], and 0.56 [0.01] mmol/g protein) and PC content (0.53 [0.03], 0.51 [0.01], and 0.49 [0.02] mmol/g protein) compared with the IIR injury-alone group (P < 0.001). Mean intestinal mucosal injury scores were significantly lower in the 3 treatment groups (2.12 [0.35], 1.75 [0.46], and 1.12 [0.35]) compared with the IIR injury-alone group (3.87 [0.35]; all, P < 0.001).

CONCLUSION

In this study, AG, melatonin, or both administered in combination were associated with improvements in oxidative markers in this rat model of IIR injury.

Urothelial signaling

The urothelium, which lines the inner surface of the renal pelvis, the ureters, and the urinary bladder, not only forms a high-resistance barrier to ion, solute and water flux, and pathogens, but also functions as an integral part of a sensory web which receives, amplifies, and transmits information about its external milieu. Urothelial cells have the ability to sense changes in their extracellular environment, and respond to chemical, mechanical and thermal stimuli by releasing various factors such as ATP, nitric oxide, and acetylcholine. They express a variety of receptors and ion channels, including P2X3 purinergic receptors, nicotinic and muscarinic receptors, and TRP channels, which all have been implicated in urothelial-neuronal interactions, and involved in signals that via components in the underlying lamina propria, such as interstitial cells, can be amplified and conveyed to nerves, detrusor muscle cells, and ultimately the central nervous system. The specialized anatomy of the urothelium and underlying structures, and the possible communication mechanisms from urothelial cells to various cell types within the bladder wall are described. Changes in the urothelium/lamina propria ("mucosa") produced by different bladder disorders are discussed, as well as the mucosa as a target for therapeutic interventions.

Evaluation of the effects of ozone therapy on Escherichia coli-induced cytitis in rat

OBJECTIVES

The aim of the study was to investigate the effect of ozone on oxidative/nitrosative stress and bladder injury caused by Escherichia coli in rat bladder.

METHODS

Twenty-one Wistar-Albino-type female rats included in the study were divided into three groups of equal number: (1) sham operation (control), (2) E. coli-only (EC), (3) EC + ozone. After ozone therapy for 3 days, urine and tissue samples were obtained for biochemical, microbiological, and histopathological analysis.

RESULTS

Tissue malondialdehyde (MDA), myeloperoxidase (MPO), and nitric oxide (NO) level were increased, whereas superoxide dismutase (SOD) and glutathione peroxidase (GPx) activity was decreased in the EC group. MDA, MPO, and NO levels were decreased, whereas SOD, GPx activity was increased in the ozone-treated group. Also, there was no bacterial translocation in this group.

CONCLUSION

The results of the present study suggest that ozone may be used as an agent to protect the bladder from oxidative/nitrosative stress occurring in cystitis.

Pharmacological inhibition of inducible nitric oxide synthase (iNOS) and nicotinamide adenine dinucleotide phosphate (NADPH) oxidase, convalesce behavior and biochemistry of hypertension induced vascular dementia in rats

Cognitive disorders are likely to increase over the coming years (5-10). Vascular dementia (VaD) has heterogeneous pathology and is a challenge for clinicians. Current Alzheimer's disease drugs have had limited clinical efficacy in treating VaD and none have been approved by major regulatory authorities specifically for this disease. Role of iNOS and NADPH-oxidase has been reported in various pathological conditions but there role in hypertension (Hypt) induced VaD is still unclear. This research work investigates the salutiferous effect of aminoguanidine (AG), an iNOS inhibitor and 4'-hydroxy-3'-methoxyacetophenone (HMAP), a NADPH oxidase inhibitor in Hypt induced VaD in rats. Deoxycorticosterone acetate-salt (DOCA-S) hypertension has been used for development of VaD in rats. Morris water-maze was used for testing learning and memory. Vascular system assessment was done by testing endothelial function. Mean arterial blood pressure (MABP), oxidative stress [aortic superoxide anion, serum and brain thiobarbituric acid reactive species (TBARS) and brain glutathione (GSH)], nitric oxide levels (serum nitrite/nitrate) and cholinergic activity (brain acetyl cholinesterase activity-AChE) were also measured. DOCA-S treated rats have shown increased MABP with impairment of endothelial function, learning and memory, reduction in serum nitrite/nitrate & brain GSH levels along with increase in serum & brain TBARS, and brain AChE activity. AG as well as HMAP significantly convalesce Hypt induced impairment of learning, memory, endothelial function, and alterations in various biochemical parameters. It may be concluded that AG, an iNOS inhibitor and HMAP, a NADPH-oxidase inhibitor may be considered as potential agents for the management of Hypt induced VaD.

Enterococcus faecalis overcomes foreign body-mediated inflammation to establish urinary tract infections

Urinary catheterization elicits major histological and immunological changes that render the bladder susceptible to microbial invasion, colonization, and dissemination. However, it is not understood how catheters induce these changes, how these changes act to promote infection, or whether they may have any protective benefit. In the present study, we examined how catheter-associated inflammation impacts infection by Enterococcus faecalis, a leading cause of catheter-associated urinary tract infection (CAUTI), a source of significant societal and clinical challenges. Using a recently optimized murine model of foreign body-associated UTI, we found that the implanted catheter itself was the primary inducer of inflammation. In the absence of the silicone tubing implant, E. faecalis induced only minimal inflammation and was rapidly cleared from the bladder. The catheter-induced inflammation was only minimally altered by subsequent enterococcal infection and was not suppressed by inhibitors of the neurogenic pathway and only partially by dexamethasone. Despite the robust inflammatory response induced by urinary implantation, E. faecalis produced biofilm and high bladder titers in these animals. Induction of inflammation in the absence of an implanted catheter failed to promote infection, suggesting that the presence of the catheter itself is essential for E. faecalis persistence in the bladder. Immunosuppression prior to urinary catheterization enhanced E. faecalis colonization, suggesting that implant-mediated inflammation contributes to the control of enterococcal infection. Thus, this study underscores the need for novel strategies against CAUTIs that seek to reduce the deleterious effects of implant-mediated inflammation on bladder homeostasis while maintaining an active immune response that effectively limits bacterial invaders.

Improvement by phytotherapeutic agent of detrusor overactivity, down-regulation of pharmacological receptors and urinary cytokines in rats with cyclophosphamide induced cystitis

PURPOSE

We characterized pharmacological effects of the phytotherapeutic agent Eviprostat® on urodynamic parameters, bladder muscarinic and purinergic receptors, and urinary cytokines in rats with cyclophosphamide induced cystitis.

MATERIALS AND METHODS

Urodynamic parameters in cyclophosphamide (150 mg/kg intraperitoneally) treated rats were measured by a cystometric method. Muscarinic and purinergic receptors in the bladder and other tissues were measured by radioreceptor assays using [N-methyl-(3)H]scopolamine methyl chloride and [(3)H]αβ-MeATP, respectively. The urinary cytokines interleukin-1β, 6 and 17 were measured with enzyme-linked immunoassay kits. Eviprostat (36 mg/kg per day twice daily for 7 days) was orally administered.

RESULTS

On cystometry the micturition interval and micturition volume were significantly decreased in cyclophosphamide vs sham treated rats, while micturition frequency, basal pressure and post-void residual urine volume were significantly increased. Repeat oral administration of Eviprostat in cyclophosphamide treated rats significantly increased the micturition interval and micturition volume, and decreased micturition frequency, basal pressure and post-void residual urine volume. The maximal number of binding sites for [N-methyl-(3)H]scopolamine methyl chloride and [(3)H]αβ-MeATP was significantly decreased in the bladder of cyclophosphamide vs sham treated rats. Such decreases were significantly attenuated by repeat Eviprostat treatment. Increased urinary cytokine levels in cyclophosphamide treated rats were also effectively attenuated by Eviprostat.

CONCLUSIONS

Repeat Eviprostat treatment significantly improved detrusor overactivity, down-regulated the expression of bladder pharmacological receptors and increased urinary cytokine levels in rats with cyclophosphamide induced cystitis. Therefore, Eviprostat may be a pharmacologically useful phytotherapeutic agent for cystitis.

Oral glutamine attenuates cyclophosphamide-induced oxidative stress in the bladder but does not prevent hemorrhagic cystitis in rats

Cyclophosphamide (CP) is widely used in the treatment of cancer and non-malignant disease states such as rheumatoid arthritis. Hemorrhagic cystitis is a major dose-limiting side effect of CP. The incidence of this side effect is related to the dosage and can be as high as 75%. Elimination of the side effects of CP can lead to better tolerance of the drug, and a more efficient therapy can be achieved for patients in need of CP treatment. Several studies have demonstrated that oxidative stress and neutrophil infiltration play important roles in CP-induced bladder damage. Glutamine is utilized under clinical conditions for preventing chemotherapeutic drug-induced side effects, based on its ability to attenuate oxidative stress. The aim of the study is to verify whether glutamine prevents CP-induced oxidative stress and bladder damage using a rat model. Adult male rats were administered 150 mg/kg body weight of CP intraperitoneally. Glutamine pretreated rats were administered 1 g/kg body weight of glutamine orally 2 h before the administration of CP. Vehicle/glutamine-treated rats served as controls. All the rats were killed 16 h after the dose of CP/vehicle. The urinary bladders were removed and used for light microscopic and biochemical studies. The markers of oxidative stress including malondialdehyde content, protein carbonyl content, protein thiol, and myeloperoxidase activity, a marker of neutrophil infiltration, were measured in bladder homogenates. CP treatment induced hemorrhagic cystitis in the rats. Pretreatment with glutamine significantly reduced CP-induced lipid peroxidation (p < 0.01), protein oxidation (p < 0.01), and increase in myeloperoxidase activity (p < 0.05). However, it did not prevent CP-induced bladder damage. The results of the present study show that glutamine pretreatment does not attenuate CP-induced hemorrhagic cystitis, although it prevents CP-induced oxidative stress and neutrophil infiltration significantly. It is therefore necessary to clarify the utility of glutamine as a chemoprotective agent before it is recommended in the market as a nutrient supplement.

Protective effect of aminoguanidine against cyclophosphamide-induced oxidative stress and renal damage in rats

BACKGROUND

Cyclophosphamide (CP) is widely used in the treatment of tumors and B-cell malignant disease, such as lymphoma, myeloma, chronic lymphocytic leukemia, and Waldenstrom's macroglobulinemia. Renal damage is one of the dose-limiting side effects of CP. Oxidative stress is reported to play important roles in CP-induced renal damage.

AIM

To find out whether aminoguanidine (AG) protects against CP-induced oxidative stress and renal damage.

METHOD

Renal damage was induced in the rats by administration of a single injection of CP at a dose of 150 mg/kg body weight intraperitoneally. For the AG pretreatment studies, the rats were injected intraperitoneally with AG at a dose of 200 mg/kg body weight 1 hour before administration of CP. The control rats received AG or saline alone. All the rats were killed 16 hours after the administration of CP or saline. The kidneys were used for histological examination by light microscopy and biochemical assays--malondialdehyde, protein carbonyl content, reduced glutathione (GSH), and the activities of antioxidant enzymes including glutathione peroxidase (GPx), glutathione S transferase (GSTase), catalase, glutathione reductase, and myeloperoxidase (MPO), a marker of neutrophil infiltration.

RESULTS

Pretreatment with AG attenuated CP-induced renal damage histologically. Pretreatment with AG prevented CP-induced lipid peroxidation, protein oxidation, depletion of reduced GSH, and loss of activities of the antioxidant enzymes including GPx, catalase, and GSTase and also MPO activity.

CONCLUSION

The results of the present study reveal that AG can prevent CP-induced renal damage by inhibiting oxidative stress. Thus, AG may be useful for prevention of the nephrotoxicity of CP.

Management of refractory hemorrhagic cystitis following hematopoietic stem cell transplantation in children

HC is a complication associated with HSCT, but occurs rarely in solid organ recipients. The reported incidence varies from <10% to more than 70%. HC is characterized by hemorrhagic inflammation in urinary tract mucosa with symptoms varying from asymptomatic microscopic hematuria to frank hematuria with clot formation and urinary tract obstruction. Early onset HC may be explained by toxicity of chemo- and/or radiotherapy, while multiple factors including viral infections and their interplay seem to be involved in late onset HC. So far, only incidence of cyclophosphamide-associated HC has been reduced with preventive treatment. Likely, once HC is established, the treatment principles are similar regardless of the etiology and depend on the intensity of HC. Prevention of urinary tract obstruction, transfusion support, analgesic, and spasmolytic therapy are generally accepted in HC management. Treatment beyond this conservative approach entails higher risk for side effects, and thus treatment escalation proportional to HC intensity is warranted. No standard and evidence-based treatment escalation algorithm has been widely adopted yet. As severe HC following HSCT is a potentially life-threatening complication, a multidisciplinary and individual approach is required in children suffering from this devastating complication.

Urothelial signaling

The urinary bladder "mucosa" or innermost portion of the bladder is composed of transitional epithelium, basement membrane, and the lamina propria. This chapter reviews the specialized anatomy of the bladder epithelium (urothelium) and speculates on possible communication mechanisms from urothelial cells to various cell types within the bladder wall. For example, beyond serving as a simple barrier, there is growing evidence that the urinary bladder urothelium exhibits specialized sensory properties and plays a key role in the detection and transmission of both physiological and nociceptive stimuli. Findings from a number of studies suggest that the urothelium exhibits both "sensor" (expressing receptors/ion channels capable of responding to thermal, mechanical, and chemical stimuli) and "transducer" (ability to release chemicals) properties. Thus, urothelial cells exhibit the ability to sense changes in their extracellular environment including the ability to respond to chemical, mechanical, and thermal stimuli that may communicate the state of the urothelial environment to the underlying nervous and muscular systems.

Effect of melatonin on the expression of Nrf2 and NF-kappaB during cyclophosphamide-induced urinary bladder injury in rat

Urotoxicity is one of the major problems associated with cyclophosphamide (CP) chemotherapy in cancer patients. Melatonin is a potent antioxidant and reduces CP-induced urotoxicity. However, the molecular mechanisms of protection offered by melatonin are not yet clear. The present study investigated the role of nuclear erythroid 2-related factor 2 (Nrf2) and nuclear factor-kappa B (NF-kappaB) on melatonin-mediated protection against CP-induced urotoxicity. CP was administered intraperitoneally at the dose of 150 mg/kg to induce urotoxicity in male Sprague-Dawley rats. Melatonin treatment (10 mg/kg) was initiated 3 days before and continued for 1 day after the CP administration. Melatonin treatment reduced the CP-induced oxidative stress and DNA damage in the urinary bladder as observed by abrogation in thiobarbituric acid-reactive substances and glutathione levels as well as comet and modified comet assay parameters. Melatonin treatment reduced the bladder damage and apoptosis as observed by histological analysis and TUNEL assay. Melatonin increased the expression of transcription factor Nrf2 as well as associated phase-II enzymes NADPH: quinone oxidoreductase-1 and heme oxygenase-1. Further melatonin treatment reduced the expression of transcription factor NF-kappaB. The results of the present study provide evidence that melatonin treatment favorably alters Nrf2 and NF-kappaB expression and, this appears to be at least in part responsible for observed protection against CP-induced urotoxicity.

Effects of fructosamine-3-kinase deficiency on function and survival of mouse pancreatic islets after prolonged culture in high glucose or ribose concentrations

Due to their high glucose permeability, insulin-secreting pancreatic beta-cells likely undergo strong intracellular protein glycation at high glucose concentrations. They may, however, be partly protected from the glucotoxic alterations of their survival and function by fructosamine-3-kinase (FN3K), a ubiquitous enzyme that initiates deglycation of intracellular proteins. To test that hypothesis, we cultured pancreatic islets from Fn3k-knockout (Fn3k(-/-)) mice and their wild-type (WT) littermates for 1-3 wk in the presence of 10 or 30 mmol/l glucose (G10 or G30, respectively) and measured protein glycation, apoptosis, preproinsulin gene expression, and Ca(2+) and insulin secretory responses to acute glucose stimulation. The more potent glycating agent d-ribose (25 mmol/l) was used as positive control for protein glycation. In WT islets, a 1-wk culture in G30 significantly increased the amount of soluble intracellular protein-bound fructose-epsilon-lysines and the glucose sensitivity of beta-cells for changes in Ca(2+) and insulin secretion, whereas it decreased the islet insulin content. After 3 wk, culture in G30 also strongly decreased beta-cell glucose responsiveness and preproinsulin mRNA levels, whereas it increased islet cell apoptosis. Although protein-bound fructose-epsilon-lysines were more abundant in Fn3k(-/-) vs. WT islets, islet cell survival and function and their glucotoxic alterations were almost identical in both types of islets, except for a lower level of apoptosis in Fn3k(-/-) islets cultured for 3 wk in G30. In comparison, d-ribose (1 wk) similarly decreased preproinsulin expression and beta-cell glucose responsiveness in both types of islets, whereas it increased apoptosis to a larger extent in Fn3k(-/-) vs. WT islets. We conclude that, despite its ability to reduce the glycation of intracellular islet proteins, FN3K is neither required for the maintenance of beta-cell survival and function under control conditions nor involved in protection against beta-cell glucotoxicity. The latter, therefore, occurs independently from the associated increase in the level of intracellular fructose-epsilon-lysines.