MESNA (2-Mercaptoethanesulfonate) Attenuates Brain, Heart, and Lung Injury Induced by Carotid Ischemia-Reperfusion in Rats.

Background: Ischemia-reperfusion (I/R) causes organ dysfunction as a result of the increased formation of various reactive oxygen metabolites, infiltration of inflammatory cells, interstitial edema, cellular dysfunction, and tissue death. Aim: The study aimed to investigate the cytoprotective effect of 2-mercaptoethanesulfonate (MESNA) against tissue damage in rats exposed to carotid ischemia-reperfusion. Materials and Methods: Twenty-four male Wistar albino rats were divided into four groups (n = 6): sham, carotid I/R, I/R + MESNA (75 mg/kg), and I/R + MESNA (150 mg/kg) groups. To induce ischemia in rats, the carotid arteries were ligated with silk sutures for 10 min; the silk suture was then opened, and 1 h reperfusion was done. MESNA (75 and 150 mg/kg) was administered intraperitoneally 30 min before ischemia-reperfusion. Tissue samples from the animals were taken for histological examination, while the serum levels of some biochemical parameters were utilized to evaluate the systemic alterations. ANOVA and Tukey's post hoc tests were applied with a significance level of 5%. Results: The ischemia-reperfusion-induced tissue damage as evidenced by increase in serum levels of alanine transaminase, aspartate aminotransferase, alkaline phosphatase, malondialdehyde, lactate dehydrogenase, and matrix metalloproteinases (MMP-1, -2, -8) was significantly (P < 0.05-0.0001) reversed after treatment with MESNA in a dose-dependent manner. Treatment with MESNA (75 and 150 mg/kg), significantly (P < 0.05-0.0001) decreased the I/R-induced increase in serum tumor necrosis factor-alpha (TNF-α) and Interleukin-1-beta (IL-1 ß). Conclusion: The results of this study suggest that MESNA has a protective effect on tissues by suppressing cellular responses to oxidants and inflammatory mediators associated with carotid ischemia-reperfusion.

Cysteine-lowering treatment with mesna against obesity: Proof of concept and results from a human phase I, dose-finding study.

AIM: To investigate whether mesna-sodium-2-mercaptoethane sulfonate) can reduce diet-induced fat gain in mice, and to assess the safety of single ascending mesna doses in humans to find the dose associated with lowering of plasma tCys by at least 30%. METHODS: C3H/HeH mice were shifted to a high-fat diet ± mesna in drinking water; body composition was measured at weeks 0, 2 and 4. In an open, phase I, single ascending dose study, oral mesna (400, 800, 1200, 1600 mg) was administered to 17 men with overweight or obesity. Mesna and tCys concentrations were measured repeatedly for a duration of 48 hours postdosing in plasma, as well as in 24-hour urine. RESULTS: Compared with controls, mesna-treated mice had lower tCys and lower estimated mean fat mass gain from baseline (week 2: 4.54 ± 0.40 vs. 6.52 ± 0.36 g; week 4: 6.95 ± 0.35 vs. 8.19 ± 0.34 g; Poverall = .002), but similar lean mass gain. In men with overweight, mesna doses of 400-1600 mg showed dose linearity and were well tolerated. Mesna doses of 800 mg or higher decreased plasma tCys by 30% or more at nadir (4h post-dosing). With increasing mesna dose, tCys AUC0-12h decreased (Ptrend < .001), and urine tCys excretion increased (Ptrend = .004). CONCLUSIONS: Mesna reduces diet-induced fat gain in mice. In men with overweight, single oral doses of mesna (800-1600 mg) were well tolerated and lowered plasma tCys efficiently. The effect of sustained tCys-lowering by repeated mesna administration on weight loss in humans deserves investigation.

Trimetazidine attenuates cyclophosphamide-induced cystitis by inhibiting TLR4-mediated NFκB signaling in mice.

AIM: Cyclophosphamide (CP)-induced cystitis is a challenging clinical problem involving inflammation and dysfunction of bladder. Trimetazidine (TMZ) is an anti-anginal drug with anti-oxidant and anti-inflammatory properties. We aimed to investigate the protective effects of TMZ in CP-induced cystitis via inhibiting TLR4/NFκB signaling. MAIN METHODS: Balb/c mice were administrated TMZ (10 or 20 mg/kg/day) intraperitoneally (i.p.) for 5 consecutive days before CP. On day 6, cystitis was induced by a single dose of CP (300 mg/kg, i.p.). Mesna (2-mercaptoethane sulfonate sodium; 30 mg/kg, i.p.) was administered 20 min before and at 4 and 8 h after the CP injection. After 24 h of cystitis induction, the bladders were removed for histopathological evaluation, contractility studies, biochemical analysis and western blotting. MTT assay was performed in a cancer cell line (MDA-MB-231) to evaluate the effect of TMZ on the cytotoxicity of CP. KEY FINDINGS: CP-induced severe cystitis was confirmed by histological disturbances and the decrease in carbachol-evoked contractions of detrusor strips, which was partially improved by TMZ (20 mg/kg/day). SOD activity and GSH content were decreased whereas TNF-α and IL-1ß levels were increased in the bladders of CP-treated mice, which were restored by TMZ or mesna. TMZ reduced the CP-induced increase in the protein expressions of caspase-3, TLR4 and phosphorylated-NFκB in bladder tissues. TMZ alone decreased the cell viability and TMZ also enhanced the cytotoxicity of CP. SIGNIFICANCE: Our study provides the first preclinical evidence that TMZ attenuates CP-induced urotoxicity by enhancing anti-oxidant capacity and suppressing inflammation possibly via downregulating TLR4-mediated NFκB signaling while augmenting the cytotoxicity of CP.

Infliximab and/or MESNA alleviate doxorubicin-induced Alzheimer's disease-like pathology in rats: A new insight into TNF-α/Wnt/ß-catenin signaling pathway.

AIMS: The current study aimed to elucidate the neurotoxic potential of DOX to induce AD-like pathology paying attention to the role of wingless-integrated/ß-catenin (Wnt/ß-catenin) signaling pathway. A major aim was to evaluate the efficacy of infliximab (IFX) either individually or in combination with 2-mercaptoethane sulfonate sodium (MESNA) on the DOX-induced neurotoxicity in rats. METHODOLOGY: AD-like pathology was induced in adult male Wistar rats by intraperitoneal (i.p.) administration of DOX at a dose of 3.5 mg/kg twice a week for 3 weeks. DOX-injected rats were then treated with either INF at a single dose of 5 mg/kg i.p. (IFX group), MESNA at a dose of 160 mg/kg/day i.p. for 4 weeks (MESNA group) or their combination at the same specified doses (INF + MESNA group). At the end of the study period, behavioral assessment was performed and the brain tissue samples were harvested at sacrifice. KEY FINDINGS: DOX-treated rats significantly exhibited AD-like brain injury, increased amyloid burden, enhanced neuroinflammation and apoptosis, and multifocal histological injury in the cerebral cortex with widespread vacuolations. IFX and MESNA significantly reversed all the aforementioned detrimental effects in the DOX-treated rats. SIGNIFICANCE: The study has provided sufficient evidence of the potential of IFX and/or MESNA to ameliorate the DOX-induced neurotoxicity, with the best improvement observed with their combined administration. A new insight has been introduced into the critical role of Wnt/ß-catenin activation.

Modulation of autophagy and transient receptor potential vanilloid 4 channels by montelukast in a rat model of hemorrhagic cystitis.

AIMS: Hemorrhagic cystitis (HC) is a major urotoxic complication of cyclophosphamide (CPA) therapy. This study investigated the uroprotective effect of montelukast on CPA-induced HC, compared to the efficacy of 2-mercaptoethane sulfonate sodium (MESNA). MAIN METHODS: Male albino rats were pretreated with MESNA (40 mg/kg/day, IP) or montelukast (10 mg/kg/day, orally) for three days then received a single dose of CPA (200 mg/kg, IP), 1 h after the last dose, and compared to CPA-treated rats receiving drug vehicle. Age-matched rats were used as controls. Bladders of rats were assessed biochemically, macroscopically and microscopically by light and electron microscope 24 h later. KEY FINDINGS: CPA injection contributed to increased bladder weight, urothelial ulceration, vascular congestion, hemorrhage, increased collagen deposition and mast cell infiltration, compared to control rats. Montelukast preconditioning suppressed mast cell infiltration and inflammatory mediators to greater extent than MESNA. Also, montelukast enhanced autophagosomes formation in detrusor myocytes and up-regulated the autophagy-related proteins (beclin-1 & LC3-II), likely through inhibition of phosphatidylinositol-3-kinase (PI3K)/protein kinase B (Akt)/mammalian target of rapamycin (mTOR) signaling pathway. Montelukast preconditioning offset the up-regulation of transient receptor potential vanilloid 4 (TRPV4) in urothelial tissue of CPA-treated rats, to greater extent than MESNA. SIGNIFICANCE: These results demonstrate the uroprotective effect of montelukast on CPA-induced HC, which appears to be more superior to MESNA. These findings suggest that montelukast can emerge as a novel strategy to protect against CPA-induced urotoxicity.

The Neuroprotective Effect of Mesna on Cisplatin-Induced Neurotoxicity: Behavioral, Electrophysiological, and Molecular Studies.

Peripheral neuropathy and cognitive impairments following cisplatin administration may interfere with the clinical usage of the drug. Mesna is a chemoprotective agent with anti-inflammatory and anti-oxidant effects. Our study aimed to investigate the protective effects of mesna against cisplatin-induced neurotoxicity. Neurotoxicity was induced by the administration of 2.5 mg/kg cisplatin twice a week for four consecutive weeks in male Wistar rats. The neuroprotective effect of mesna (150 mg/kg/day) was evaluated through behavioral, electrophysiological, and molecular studies. Cisplatin treatment caused passive avoidance memory impairment, increased anxiety-like behaviors, altered thermal sensitivity, and decreased muscle strength in a grip strength test. Our electrophysiological studies indicated that administration of cisplatin induced peripheral sensory neuropathy and decreased the amplitudes of the compound action potential of sensory nerves. Cisplatin administration increased MDA and 4-HNE levels and decreased anti-oxidant (SOD and GPx) enzymes. Proinflammatory cytokines (IL-1ß and TNF-α) and metalloproteinase-2 and 9 (MMP-2/9) were increased by cisplatin treatment. Morphological alterations were observed in the dorsal root ganglion (DRG) of cisplatin-treated rats. Cognitive impairments, anxiety, muscle strength, and thermal sensitivity changes induced by cisplatin were improved with mesna treatment. The reduced conduction velocity in sensory nerves was recovered in the cisplatin + mesna group. Mesna partially alleviated redox imbalance, reduced the proinflammatory cytokines, and MMP-2/9 levels. Mesna administration also relieved the morphological changes in DRG of cisplatin-treated rats. In conclusion, our results revealed that mesna can alleviate cisplatin-induced central and peripheral nervous system toxicity. These results support the concept that chemotherapy-induced neuropathy can be partially inhibited via mesna.

Mesna Alleviates Cerulein-Induced Acute Pancreatitis by Inhibiting the Inflammatory Response and Oxidative Stress in Experimental Rats.

BACKGROUND: Acute pancreatitis (AP) is a sudden inflammation of the pancreas that may be life-threatening disease with high mortality rates, particularly in the presence of systemic inflammatory response and multiple organ failure. Oxidative stress has been shown to be involved in the pathophysiology of acute pancreatitis. AIM: This study is designed to investigate the possible effect of mesna on an experimental model of cerulein-induced acute pancreatitis. METHODS: Animals were divided into five groups: Group 1 served as a control group given the saline; group II (mesna group) received mesna at a dose of (100 mg/kg per dose, i.p.) four times; group III (acute pancreatitis group) received cerulein at a dose of (20 µg/kg/dose, s.c.) four times with 1-h intervals; group VI, cerulein + mesna, was treated with mesna at a dose of (100 mg/kg, i.p.) 15 min before each cerulein injection. RESULTS: Animals with acute pancreatitis showed elevated serum amylase and lipase levels. Biochemical parameters showed increased pancreatic tumor necrosis factors-α (TNF-α) and interleukin-1ß (IL-1ß) levels. A disturbance in oxidative stress markers was evident by elevated pancreatic lipid peroxides (TBARS) and decline in pancreatic antioxidants' concentrations including reduced glutathione (GSH); superoxide dismutase (SOD); and glutathione peroxidase (GSH-Px). Histological examination confirmed pancreatic injury. Pre-treatment with mesna was able to abolish the changes in pancreatic enzymes, oxidative stress markers (TBARS, SOD, GSH and GSH-Px), pancreatic inflammatory markers (TNF-α, IL-1ß) as well as histological changes. CONCLUSIONS: Mesna mitigates AP by alleviating pancreatic oxidative stress damage and inhibiting inflammation.

Cyclophosphamide-induced cystitis results in NLRP3-mediated inflammation in the hippocampus and symptoms of depression in rats.

Recent breakthroughs demonstrate that peripheral diseases can trigger inflammation in the brain, causing psychosocial maladies, including depression. While few direct studies have been made, anecdotal reports associate urological disorders with mental dysfunction. Thus, we investigated if insults targeted at the bladder might elicit behavioral alterations. Moreover, the mechanism of neuroinflammation elicited by other peripheral diseases involves the NOD-like receptor family pyrin domain containing 3 (NLRP3) inflammasome, which is present in microglia in the brain and cleaves and activates proinflammatory cytokines such as IL-1ß. Thus, we further explored the importance of NLRP3 in behavioral and neuroinflammatory changes. Here, we used the well-studied cyclophosphamide (CP)-treated rat model. Importantly, CP and its metabolites do not cross the blood-brain barrier or trigger inflammation in the gut, so that any neuroinflammation is likely secondary to bladder injury. We found that CP triggered an increase in inflammasome activity (caspase-1 activity) in the hippocampus but not in the pons. Evans blue extravasation demonstrated breakdown of the blood-brain barrier in the hippocampal region and activated microglia were present in the fascia dentata. Both changes were dependent on NLRP3 activation and prevented with 2-mercaptoethane sulfonate sodium (Mesna), which masks the effects of the CP metabolite acrolein in the urine. Finally, CP-treated rats displayed depressive symptoms that were prevented by NLRP3 inhibition or treatment with Mesna or an antidepressant. Thus, we conclude that CP-induced cystitis causes NLRP3-dependent hippocampal inflammation leading to depression symptoms in rats. This study proposes the first-ever causative explanation of the previously anecdotal link between benign bladder disorders and mood disorders.

Agonists that stimulate secretion promote the recruitment of CFTR into membrane lipid microdomains.

The cystic fibrosis transmembrane conductance regulator (CFTR) is a tightly regulated anion channel that mediates secretion by epithelia and is mutated in the disease cystic fibrosis. CFTR forms macromolecular complexes with many proteins; however, little is known regarding its associations with membrane lipids or the regulation of its distribution and mobility at the cell surface. We report here that secretagogues (agonists that stimulate secretion) such as the peptide hormone vasoactive intestinal peptide (VIP) and muscarinic agonist carbachol increase CFTR aggregation into cholesterol-dependent clusters, reduce CFTR lateral mobility within and between membrane microdomains, and trigger the fusion of clusters into large (3.0 µm2) ceramide-rich platforms. CFTR clusters are closely associated with motile cilia and with the enzyme acid sphingomyelinase (ASMase) that is constitutively bound on the cell surface. Platform induction is prevented by pretreating cells with cholesterol oxidase to disrupt lipid rafts or by exposure to the ASMase functional inhibitor amitriptyline or the membrane-impermeant reducing agent 2-mercaptoethanesulfonate. Platforms are reversible, and their induction does not lead to an increase in apoptosis; however, blocking platform formation does prevent the increase in CFTR surface expression that normally occurs during VIP stimulation. These results demonstrate that CFTR is colocalized with motile cilia and reveal surprisingly robust regulation of CFTR distribution and lateral mobility, most likely through autocrine redox activation of extracellular ASMase. Formation of ceramide-rich platforms containing CFTR enhances transepithelial secretion and likely has other functions related to inflammation and mucosal immunity.

S-allyl cysteine ameliorates cyclophosphamide-induced downregulation of urothelial uroplakin IIIa with a concomitant effect on expression and release of CCL11and TNF-α in mice.

BACKGROUND: The aim of this study was to evaluate the modulatory effect of S-allyl cysteine against cyclophosphamide-induced changes in uroplakin IIIa, CCL11 and TNF-α. METHODS: Mice were treated with cyclophosphamide (200mg/kg×7 d, ip). S-allyl cysteine (150mg/kg×7d, ip), and comparator compound mesna (40mg/kg×7d, ip) were administered 1h before and 4h after each cyclophosphamide dose. The urinary bladder was analysed for mRNA and protein changes in uroplakin IIIa (UPIIIa), CCL11 and TNF-α and histopathological findings. RESULTS: Cyclophosphamide caused hemorrhagic cystitis formation and downregulation of UPIIIa. These changes were accompanied by upregulation of CCL11 and TNF-α. S-allyl cysteine attenuated these changes including protection at histological level. Mesna which was used as a comparator drug also showed protection. However, relatively S-allyl cysteine showed a stronger protective effect than mesna. CONCLUSION: These findings highlight a correlation between downregulaion of UPIIIa and enhanced production of inflammatory biomarkers and protective effects of S-allyl cysteine which has been reported to be a potent uroprotective agent. The present study strengthens its role which could be clinically exploited in chemotherapy regimen.

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.

Histone deacetylase inhibitors mediate DNA damage repair in ameliorating hemorrhagic cystitis.

Hemorrhagic cystitis is an inflammatory and ulcerative bladder condition associated with systemic chemotherapeutics, like cyclophosphomide. Earlier, we reported reactive oxygen species resulting from cyclophosphamide metabolite, acrolein, causes global methylation followed by silencing of DNA damage repair genes. Ogg1 (8-oxoguanine DNA glycosylase) is one such silenced base excision repair enzyme that can restore DNA integrity. The accumulation of DNA damage results in subsequent inflammation associated with pyroptotic death of bladder smooth muscle cells. We hypothesized that reversing inflammasome-induced imprinting in the bladder smooth muscle could prevent the inflammatory phenotype. Elevated recruitment of Dnmt1 and Dnmt3b to the Ogg1 promoter in acrolein treated bladder muscle cells was validated by the pattern of CpG methylation revealed by bisulfite sequencing. Knockout of Ogg1 in detrusor cells resulted in accumulation of reactive oxygen mediated 8-Oxo-dG and spontaneous pyroptotic signaling. Histone deacetylase (HDAC) inhibitor, suberoylanilide hydroxamic acid (SAHA), restored Ogg1 expression in cells treated with acrolein and mice treated with cyclophosphamide superior to the standard of care, mesna or nicotinamide-induced DNA demethylation. SAHA restored cyclophosphamide-induced bladder pathology to that of untreated control mice. The observed epigenetic imprinting induced by inflammation suggests a new therapeutic target for the treatment of hemorrhagic cystitis.

Synthesis of Reactive Polymers for Acrolein Capture Using AGET ATRP.

Acrolein is a toxic metabolite of the anticancer agent cyclophosphamide (CP). Current strategies to mitigate acrolein toxicity are insufficient, and in this brief article, we report the synthesis of well-defined low molecular weight block copolymers using activators generated by electron transfer atom transfer radical polymerization (AGET ATRP) capable of reacting with the cytotoxic small molecule acrolein. Acrolein reactivity was introduced into the block copolymers via incorporation of either (a) aminooxy or (b) sulfhydryl groups. The cytoprotective effect of the polymers was compared to sodium 2-sulfanylethanesulfonate (mesna) the current gold standard for protection from CP urotoxicity, and we found that the polymers bearing sulfhydryl moieties demonstrated superior cytoprotective activity.

Treatment with Mesna and n-3 polyunsaturated fatty acids ameliorates experimental ulcerative colitis in rats.

Oxidative damage is a central feature of ulcerative colitis. Here, we tested whether the antioxidant Mesna, when administered alone or in combination with n-3 polyunsaturated fatty acids (n-3 PUFAs), affects the outcome of dextran sodium sulphate (DSS)-induced ulcerative colitis in rats. After the induction of colitis, DSS-treated rats were further treated orally (p.o), intraperitoneally (i.p) or intrarectally (i.r) for either 7 or 14 days with Mesna, n-3 PUFAs or both. Rats were euthanized at the end of each treatment period. Clinical disease activity index was recorded throughout the experiment. At necropsy colorectal gross lesions were scored. Colitis was scored histologically, and the expression of myeloperoxidase (MPO), caspase-3, inducible nitric oxide synthase (iNOS) and nuclear factor κB (NF-κΒ) in colonic tissue was assessed by immunohistochemistry. Mesna alone was sufficient to significantly reduce colorectal tissue damage when administered orally or intraperitoneally. Orally coadministered n-3 PUFAs enhanced this effect, resulting in the significant suppression of DSS colitis after 7 days, and a remarkable recovery of colorectal mucosa was evident after 14 days of treatment. The amelioration of colon pathology co-existed with a significant decrease in MPO expression, overexpression of iNOS and reduction of nuclear NF-κB p65 in inflammatory cells, and the suppression of apoptosis in colonic epithelial cells. The simultaneous administration of Mesna and n-3 PUFAs is particularly effective in ameliorating DSS colitis in rats, by reducing oxidative stress, inflammation and apoptosis, probably through a mechanism that involves the inhibition of NF-κB and overexpression of iNOS.

Characterization of Batracylin-induced Renal and Bladder Toxicity in Rats.

Batracylin (NSC-320846) is a dual inhibitor of DNA topoisomerases I and II. Batracylin advanced as an anticancer agent to Phase I clinical trials where dose limiting hemorrhagic cystitis (bladder inflammation and bleeding) was observed. To further investigate batracylin's mechanism of toxicity, studies were conducted in Fischer 344 rats. Once daily oral administration of 16 or 32 mg/kg batracylin to rats for 4 days caused overt toxicity. Abnormal clinical observations and adverse effects on clinical pathology, urinalysis, and histology indicated acute renal damage and urothelial damage and bone marrow dysfunction. Scanning electron microscopy revealed sloughing of the superficial and intermediate urothelial layers. DNA damage was evident in kidney and bone marrow as indicated by histone γ-H2AX immunofluorescence. After a single oral administration of 16 or 32 mg/kg, the majority of batracylin was converted to N-acetylbatracylin (NAB) with a half-life of 4 hr to 11 hr. Mesna (Mesnex™), a drug known to reduce the incidence of hemorrhagic cystitis induced by ifosfamide or cyclophosphamide, was administered to rats prior to batracylin, but did not alleviate batracylin-induced bladder and renal toxicity. These findings suggest that batracylin results in DNA damage-based mechanisms of toxicity and not an acrolein-based mechanism of toxicity as occurs after ifosfamide or cyclophosphamide administration.

After myringotomy, can topical Mesna application be an alternative method to ventilation tube application?

Sodium-2-mercaptoethanesulfonate (Mesna) is a mucolytic substance that is also used for chemically assisted tissue dissection in otological surgery. We investigated the effects of Mesna as a chemical agent on the closing time of perforation of the eardrum in an experimental animal model. We performed simple myringotomy with a knife on 44 tympanic membranes of 22 rats. Four rats were excluded from the study because of serosity in their ears. Rats were divided into two study groups and a control group. These groups were the Mesna-administered group (Group A) (8 rats, 15 tympanic membranes), the saline-administered group (Group B) (8 rats, 14 tympanic membranes) and the control (native) group (6 rats, 11 tympanic membranes) (Group C). We applied Mesna locally for 20 min following myringotomy. Examination was made with an otoendoscope on days 1, 2, 3, 5, and 7, and patency rates were recorded. According to our results, we found that the closing time of the tympanic membrane was significantly longer in the Mesna group than in the saline administrated and native group. After myringotomy procedure, the application of a single dose of Mesna may contribute to the recovery duration of middle-ear pathologies by delaying the closing time of tympanic membrane perforation. However, Mesna cannot be an alternative method for the application of ventilation tubes.

Enzymatic and non-enzymatic mechanisms of dimesna metabolism.

The chemical reduction of the disulfide homodimer dimesna to its constituent mesna moieties is essential for its mitigation of nephrotoxicity associated with cisplatin and ifosfamide anticancer therapies and enhancement of dialytic clearance of the cardiovascular risk factor homocysteine. The objective of this study was to investigate potential enzymatic and non-enzymatic mechanisms of intracellular dimesna reduction. Similar to endogenous intracellular disulfides, dimesna undergoes thiol-disulfide exchange with thiolate anion-forming sulfhydryl groups via the two-step SN2 reaction. Determination of equilibrium constants of dimesna reduction when mixed with cysteine or glutathione provided a mechanistic explanation for dramatic cysteine and homocysteine depletion, but sparing of the endogenous antioxidant glutathione, previously observed during mesna therapy. Dimesna was reduced by recombinant enzymes of the thioredoxin system; however, oxidation of NADPH by the glutaredoxin system was only observed in the presence of combined dimesna and reduced glutathione, suggesting formation of oxidized glutathione following an initial non-enzymatic reduction of dimesna. Production of mesna by enzymatic and non-enzymatic mechanisms in HeLa cell lysate following dimesna incubation was demonstrated by a loss in mesna production following protein denaturation and prediction of residual non-enzymatic mesna production by mathematical modeling of thiol-disulfide exchange reactions. Reaction modeling also revealed that mixed disulfides make up a significant proportion of intracellular thiols, supporting their role in providing additional nephroprotection, independent of direct platinum conjugation.

Prevention of cyclophosphamide-induced hemorrhagic cystitis by resveratrol: a comparative experimental study with mesna.

PURPOSE: Hemorrhagic cystitis (HC) is the most common urotoxic side effect of cyclophosphamide (CP). The aim of this study was to compare the classical efficacy of mesna (2-mercaptoethane sulfonate sodium) with three different doses of resveratrol (RES) on cyclophosphamide-induced HC in rats. METHODS: Forty-six male Sprague-Dawley rats were divided into six groups. Group 1 served as a negative control (sham). Five groups received a single dose of cyclophosphamide (150 mg/kg) intraperitoneally at the same time. Groups 2, 3, 4, 5, and 6 received only CP, CP + 20 mg/kg RES, CP + 40 mg/kg RES, CP + 80 mg/kg RES, and CP + classical protocol of three doses of mesna (30 mg/kg three times), respectively. Antioxidants, cytokines, and malondialdehyde levels were measured in all groups. In addition, histopathological alterations in tissues were examined. RESULTS: CP administration induced severe HC with marked edema, hemorrhage, and inflammation in group 2. RES 20 mg/kg showed meaningful protection against bladder damage compared to the control group. It was seen that RES 40 mg/kg gave weaker protection but RES 80 mg/kg was not found to be effective. CONCLUSION: In conclusion, marked bladder protection was found in 20 and 40 mg/kg RES applications compared to the control group, but this protection was weaker than with mesna.

Metformin exhibits radiation countermeasures efficacy when used alone or in combination with sulfhydryl containing drugs.

Metformin, a biguanide drug used in the treatment of type II diabetes, was evaluated alone and in combination with amifostine, captopril, MESNA or N-acetyl-cysteine (NAC) for its ability to protect when administered 24 h after irradiation. Mouse embryo fibroblasts (MEF), human microvascular endothelial cells (HMEC) and SA-NH mouse sarcoma cells were exposed to 4 Gy in vitro. C3H mice were exposed to 7 Gy and evaluated utilizing an endogenous spleen colony assay system. Amifostine and WR1065, administered 30 min prior to irradiation, were used as positive controls. Treatment of MEF, HMEC and SA-NH cells with metformin elevated survival levels by 1.4-, 1.5- and 1.3-fold compared to 1.9-, 1.8- and 1.6-fold for these same cells treated with WR1065, respectively. Metformin (250 mg/kg) was effective in protecting splenic cells from a 7 Gy dose in vivo (protection factor = 1.8). Amifostine (400 mg/kg), administered 30 min prior to irradiation resulted in a 2.6-fold survival elevation, while metformin administered 24 h after irradiation in combination with NAC (400 mg/kg), MESNA (300 mg/kg) or captopril (200 mg/kg) enhanced survival by 2.6-, 2.8- and 2.4-fold, respectively. Each of these agents has been approved by the FDA for human use and each has a well characterized human safety profile. Metformin alone or in combination with selected sulfhydryl agents possesses radioprotective properties when administered 24 h after radiation exposure comparable to that observed for amifostine administered 30 min prior to irradiation making it a potentially useful agent for radiation countermeasures use.

The control of hyperhomocysteinemia through thiol exchange mechanisms by mesna.

In hyperhomocysteinemic patients, after reaction with homocysteine-albumin mixed disulfides (HSS-ALB), mesna (MSH) forms the mixed disulfide with Hcy (HSSM) which can be removed by renal clearance, thus reducing the plasma concentration of total homocysteine (tHcy). In order to assess the HSS-ALB dethiolation via thiol exchange reactions, the distribution of redox species of cysteine, cysteinylglycine, homocysteine and glutathione was investigated in the plasma of healthy subjects: (i) in vitro, after addition of 35 µM reduced homocysteine (HSH) to plasma for 72 h, followed by MSH addition (at the concentration range 10-600 µM) for 25 min; (ii) in vivo, after oral treatment with methionine (methionine, 200 mg/kg body weight, observation time 2-6 h). In both experiments the distribution of redox species, but not the total amount of each thiol, was modified by thiol exchange reactions of albumin and cystine, with changes thermodynamically related to the pKa values of thiols in the corresponding mixed disulfides. MSH provoked a dose-response reversal of the redox state of aged plasma, and the thiol action was confirmed by in vivo experiments. Since it was observed that the dimesna production could be detrimental for the in vivo optimization of HSSM formation, we assume that the best plasma tHcy lowering can be obtained at MSH doses producing the minimum dimesna concentration in each individual.