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Nitric oxide (NO) plays an important and diverse signalling role in the cardiovascular system, contributing to the regulation of vascular tone, endothelial function, myocardial function, haemostasis, and thrombosis, amongst many other roles. NO is synthesised through the nitric oxide synthase (NOS)-dependent L-arginine-NO pathway, as well as the nitrate-nitrite-NO pathway. The three isoforms of NOS, namely neuronal (NOS1), inducible (NOS2), and endothelial (NOS3), have different localisation and functions in the human body, and are consequently thought to have differing pathophysiological roles. Furthermore, as we continue to develop a deepened understanding of the different roles of NOS isoforms in disease, the possibility of therapeutically modulating NOS activity has emerged. Indeed, impaired (or dysfunctional), as well as overactive (or dysregulated) NOS activity are attractive therapeutic targets in cardiovascular disease. This review aims to describe recent advances in elucidating the physiological role of NOS isoforms within the cardiovascular system, as well as mechanisms of dysfunctional and dysregulated NOS in cardiovascular disease. We then discuss the modulation of NO and NOS activity as a target in the development of novel cardiovascular therapeutics. [ABSTRACT FROM AUTHOR]

Objective: Testicular tissues and sperms are typically vulnerable to oxidative stress and inflammation. Despite functioning as a signaling molecule in different physiological and pathological processes, hydrogen sulfide (H2S) role in the reproductive system is not fully recognized. This study aimed to assess whether H2S could counteract the testicular damage that acrylamide (AC) causes in male rats. Methods: Forty male rats were equally divided randomly into four groups: normal control, AC, H2S, and AC + H2S who received normal saline, 40 mg/Kg of AC, 200 µg/Kg of sodium hydrosulfide NaHS (H2S donor), and 40 mg/Kg of AC + 200 µg/Kg of NaHS by intraperitoneal injection for 14 consecutive days, respectively. Body and testes weights, sperm count and motility, lactate dehydrogenase isoenzyme-x (LDH-X), serum testosterone level, oxidative parameters, the expression level of inducible nitric oxide synthase (iNOS), inflammatory cytokines, and histopathological alterations were evaluated. Results: The reduction in relative testicular weights, sperm count, and motility served as evidence of the harmful effects of AC. However, these values were reversed when H2S and AC were combined. Additionally, AC significantly decreased serum testosterone level, testicular LDH-X activity, superoxide dismutase, catalase, and reduced glutathione. While malondialdehyde, expression levels of iNOS protein and inflammatory cytokines (TNF-α, IL-1β, and IL-6) levels were elevated. Interestingly, the co-administration of H2S with AC reversed these values, demonstrating an opposing effect in the previous parameters. Conclusion: H2S exhibited a protective effect in the rat model of testicular toxicity induced by AC, which may be associated with the suppression of iNOS expression, proinflammatory cytokines, and the inhibition of oxidative stress injury. [ABSTRACT FROM AUTHOR]

Nitric oxide (NO) plays an important and diverse signalling role in the cardiovascular system, contributing to the regulation of vascular tone, endothelial function, myocardial function, haemostasis, and thrombosis, amongst many other roles. NO is synthesised through the nitric oxide synthase (NOS)-dependent L-arginine-NO pathway, as well as the nitrate-nitrite-NO pathway. The three isoforms of NOS, namely neuronal (NOS1), inducible (NOS2), and endothelial (NOS3), have different localisation and functions in the human body, and are consequently thought to have differing pathophysiological roles. Furthermore, as we continue to develop a deepened understanding of the different roles of NOS isoforms in disease, the possibility of therapeutically modulating NOS activity has emerged. Indeed, impaired (or dysfunctional), as well as overactive (or dysregulated) NOS activity are attractive therapeutic targets in cardiovascular disease. This review aims to describe recent advances in elucidating the physiological role of NOS isoforms within the cardiovascular system, as well as mechanisms of dysfunctional and dysregulated NOS in cardiovascular disease. We then discuss the modulation of NO and NOS activity as a target in the development of novel cardiovascular therapeutics.

Chronic myeloid leukemia (CML) is characterized by constitutive BCR–ABL kinase activity, an aggressive proliferation of immature cells, and reduced differentiation. Targeting tyrosine kinase activity of BCR–ABL with imatinib is an effective therapy for the newly diagnosed CML patients; however, 20%–30% of the patients initially treated with imatinib eventually experience treatment failure. Therefore, early identification of these patients is of high clinical relevance. In the present study, we by undertaking a direct comparison of inducible NOS (iNOS) status in neutrophils from healthy volunteers, newly diagnosed, imatinib responder, and resistant CML patients as well as by conducting in vitro studies in K562 cells demonstrated that inhibition of BCR–ABL by imatinib or siRNA significantly enhanced NO generation and iNOS expression. Indeed, patients exhibiting treatment failure or imatinib resistance were less likely to induce NO generation/iNOS expression. Our findings further demonstrated that imatinib mediated antiproliferative and proapoptotic effect in BCR–ABL+ cells associated with enhanced iNOS expression, and it was significantly prevented in the presence of L‐NAME, 1400W, or iNOS siRNA. Overexpression of iNOS in K562 cells expectedly enhanced imatinib sensitivity on cytostasis and apoptosis, even at lower concentration (0.1 μM) of imatinib. Mechanistically, imatinib or BCR–ABL siRNA following deglutathionylation of NF‐κB, enhanced its binding to iNOS promoter and induced iNOS transcription. Deglutathionylation of procaspase‐3 however associated with increased caspase‐3 activity and cell apoptosis. Taken together, results obtained suggest that monitoring NO/iNOS level could be useful to identify patients likely to be responsive or resistant to imatinib and can be used to personalized alternative therapy. [ABSTRACT FROM AUTHOR]

Transient congenital hypothyroidism (TCH) has long-lasting consequences on the cardiovascular system during adulthood. The aim of this study was to determine whether nitric oxide (NO) and NO-producing enzymes are involved in impaired cardiac function as well as decreased tolerance to ischemia-reperfusion (IR) injury in adult male rats with TCH. Pregnant rats were divided into control and hypothyroid groups. Male offspring rats were categorized in control and hypothyroid (TCH) groups at week 16. Levels of NOx (nitrate+nitrite) and neuronal NOS (nNOS), inducible NOS (iNOS), and endothelial NOS (eNOS) were measured in hearts of rats and isolated perfused hearts from both groups were subjected to IR. Levels of NOx and NOSs were also measured in both groups after ischemia. Compared with controls, heart NOx levels were higher at baseline (48.0 ± 4.9 vs. 35.0 ± 2.6 μmol/L; P = 0.034) and following IR (103.6 ± 4.2 vs. 70.2 ± 2.7 μmol/L; P < 0.001) in rat with TCH. At baseline, compared with controls, heart iNOS and nNOS levels were significantly higher in rats with TCH (6.12 ± 0.34 vs. 4.78 ± 0.27 ng/mg protein; P = 0.008 for iNOS and 4.87 ± 0.28 vs. 3.55 ± 0.23 ng/mg protein; P = 0.003 for nNOS). Following IR, in rats with TCH, heart iNOS levels increased (11.75 ± 2.02 vs. 6.12 ± 0.34, ng/mg protein; P = 0.015) whereas nNOS level decreased (4.10 ± 0.25 vs. 4.87 ± 0.28 ng/mg protein; P = 0.063). Adverse effects of TCH on cardiac function are associated with increased ratio of iNOS/eNOS; in addition, increased heart nNOS levels are involved in impaired cardiac function while its decrease is associated with decreased tolerance to IR injury. [ABSTRACT FROM AUTHOR]

In the failing heart, iNOS is expressed by both macrophages and cardiomyocytes. We hypothesized that inflammatory cell-localized iNOS exacerbates left ventricular (LV) remodeling. Wild-type (WT) C57BL/6 mice underwent total body irradiation and reconstitution with bone marrow from iNOS mice (iNOSc) or WT mice (WTc). Chimeric mice underwent coronary ligation to induce large infarction and ischemic heart failure (HF), or sham surgery. After 28 days, as compared with WTc sham mice, WTc HF mice exhibited significant ( p < 0.05) mortality, LV dysfunction, hypertrophy, fibrosis, oxidative/nitrative stress, inflammatory activation, and iNOS upregulation. These mice also exhibited a ~twofold increase in circulating Ly6C pro-inflammatory monocytes, and ~sevenfold higher cardiac M1 macrophages, which were primarily CCR2 cells. In contrast, as compared with WTc HF mice, iNOSc HF mice exhibited significantly improved survival, LV function, hypertrophy, fibrosis, oxidative/nitrative stress, and inflammatory activation, without differences in overall cardiac iNOS expression. Moreover, iNOSc HF mice exhibited lower circulating Ly6C monocytes, and augmented cardiac M2 macrophages, but with greater infiltrating monocyte-derived CCR2 macrophages vs. WTc HF mice. Lastly, upon cell-to-cell contact with naïve cardiomyocytes, peritoneal macrophages from WT HF mice depressed contraction, and augmented cardiomyocyte oxygen free radicals and peroxynitrite. These effects were not observed upon contact with macrophages from iNOS HF mice. We conclude that leukocyte iNOS is obligatory for local and systemic inflammatory activation and cardiac remodeling in ischemic HF. Activated macrophages in HF may directly induce cardiomyocyte contractile dysfunction and oxidant stress upon cell-to-cell contact; this juxtacrine response requires macrophage-localized iNOS. [ABSTRACT FROM AUTHOR]

83 Structures of human nNOS, 55 structures of human eNOS, 13 structures of iNOS, and about 126 reported NOS-bound compounds are summarized and analyzed. Structural and statistical analysis show that, at least one copy of each analyzed compound binds to the active site (the substrate arginine binding site) of human NOS. And binding features of the three isoforms show differences, but the binding preference of compounds is not in the way helpful for inhibitor design targeting nNOS and iNOS, or for activator design targeting eNOS. This research shows that there is a strong structural and functional similarity between oxygenase domains of human NOS isoforms, especially the architecture, residue composition, size, shape, and distribution profile of hydrophobicity, polarity and charge of the active site. The selectivity and efficacy of inhibitors over the rest of isoforms rely a lot on chance and randomness. Further increase of selectivity via rational improvement is uncertain, unpredictable and unreliable, therefore, to achieve high selectivity through targeting this site is complicated and requires combinative investigation. After analysis on the current two targeting sites in NOS, the highly conserved arginine binding pocket and H4B binding pocket, new potential drug-targeting sites are proposed based on structure and sequence profiling. This comprehensive analysis on the structure and interaction profiles of human NOS and bound compounds provides fresh insights for drug discovery and pharmacological research, and the new discovery here is practically applied to guide protein-structure based drug discovery., Competing Interests: Jianshu Dong, Dié Li, Lei Kang, Chenbing Luo and Jiangyun Wang declare that they have no conflict of interest., (© The Author(s) 2023.)

Licofelone is a COX/5-LOX inhibitor, which recently was approved as an effective treatment for osteoarthritis. Beside its analgesic and anti-inflammatory effects, some reports show neuro-protective properties for this agent in central nervous system. Several lines of evidence declare the involvement of COX or LOX isoenzymes in epileptic disorders. To set the foundation for future research into the neurobiology of licofelone as a potential therapeutic agent, we studied the effect of licofelone in an animal model of epilepsy. Although different neurotransmitters and neuro-modulators like nitric oxide were introduced as suggested targets of licofelone, the underlying mechanisms of central effects of this drug are not still fully understood. We have utilized pentylenetetrazole-induced clonic seizure model to investigate the behavioral consequences of licofelone administration and its possible mechanisms in seizure susceptibility. Licofelone revealed anticonvulsant properties at the dose of 10 mg/kg (i.p) or higher in mice. Pre-treatment with NO (nitric oxide) donor, l-arginine, reversed this anticonvulsant effects dose dependently. L-NAME, as a non-selective nitric oxide synthase (NOS) inhibitor, potentiated the anticonvulsant effects of licofelone. A neuronal NOS inhibitor, 7-NI did not affect seizure threshold alone or in combination with licofelone. Using non-effective doses of selective inhibitors of inducible NOS, aminoguanidine or 1400W, significantly increased the seizure threshold when were accompanied by licofelone in low doses. These data support the involvement of NO as an important role player in the central neuro-protective properties of licofelone. Furthermore, it implies that down regulation of iNOS seems crucial for anticonvulsant properties of this COX/5-LOX inhibitor in seizure susceptibility. [ABSTRACT FROM AUTHOR]

Approximately more than 50% of patients with depression have the co-occurrence of anxiety, which complicates the treatment of disease. Recently, social isolation stress (SIS) paradigm has been suggested as an animal model to investigate the underlying mechanism involved in depression–anxiety co-occurrence. In this study, applying six weeks of SIS to adolescent mice, we tested whether nitrergic system plays a role in co-occurrence of depression and anxiety. In this study, comparisons between socially and isolated conditioned (SC and IC) animals showed that SIS induces behaviors relevant to depression and anxiety in IC mice and in addition, nitrergic system is involved in mediating the negative outcomes of SIS. Administration of subeffective doses of aminoguanidine (a specific inducible nitric oxide synthase inhibitor or iNOS, 50 mg/kg) and L-NAME (non-specific inhibitor of NOS, 10 mg/kg) significantly reversed the negative effects of SIS on behavioral profile as well as nitrite levels in the cortex of IC mice, Although administration of subeffective dose of 7-nitroindazole (a specific neuronal NOS inhibitor, 25 mg/kg) decreased the nitrite levels in the hippocampus, but had no effect on depressant and anxiogenic effects of SIS. Results of this study confirmed that SIS is an appropriate animal model to investigate the potential mechanisms in depression–anxiety co-occurrence. We also showed that nitrergic system has contributed to co-occurrence of depression and anxiety in IC mice as an underlying mechanism. [ABSTRACT FROM AUTHOR]

Fifty two compounds based on 5-nitropyrimidine- 2,4-dione moiety have been synthesized and evaluated for their inhibitory potency on the production of nitric oxide. Among them, compound 36 inhibited the production of nitric oxide (IC50: 8.6 μM) on lipopolysaccharide- induced RAW 264.7 cells and inducible nitric oxide synthase activity (IC50: 6.2 μ), as well as exerted no potential cytotoxicity (IC50 > 80.0 μ). Docking study confirmed that compound 36 was an inducible nitric oxide synthase inhibitor with perfect binding to the active site of inducible nitric oxide synthase. At a dose of 10 mg/kg, oral administration of 36 possessed protective properties in carrageenaninduced paw edema of male ICR mice. [ABSTRACT FROM AUTHOR]

The present study was designed to evaluate the effect of Naringin on memory of unstressed and stressed Swiss young albino mice. Naringin (80 mg/kg, i.p.) and donepezil (10 mg/kg) were administered for 21 successive days to separate groups of unstressed and stressed mice. The nootropic activity was evaluated using elevated plus maze and Hebbs Williams Maze. Brain acetylcholinesterase (AChE), brain nitrite and plasma corticosterone levels were also estimated. unpredictable chronic mild stress was produced by using different stressors. Naringin (80 mg/kg) and donepezil significantly showed memory enhancing activity in both unstressed and stressed mice. Naringin significantly reduced brain AChE activity and brain nitrite levels in both unstressed and stressed mice. Naringin (80 mg/kg) significantly reversed scopolamine-induced amnesia in unstressed and stressed mice. 7-Nitroindazole [a neuronal nitric oxide synthase (NOS) inhibitor] and aminoguanidine (an inducible NOS inhibitor) significantly enhanced memory improving activity and brain nitrite decreasing effect of naringin in unstressed and stressed mice respectively. Plasma corticosterone levels were significantly decreased by naringin (80 mg/kg) in stressed mice as compared to its control. Thus, naringin showed memory enhancing activity in unstressed mice probably by decreasing brain AChE activity and by inhibition of neuronal NOS. The memory enhancing activity of naringin in stressed mice might be due to decrease in brain AChE activity, inhibition of inducible NOS and also by decreasing the elevated plasma corticosterone levels. [ABSTRACT FROM AUTHOR]

Myeloid-derived suppressor cells (MDSCs) are critical mediators of tumor-associated immune suppression, with their numbers and activity strongly increased in most human cancers and animal models. MDSCs suppress anti-tumor immunity through multiple mechanisms, including the manipulation of arginine and tryptophan metabolism by such factors as arginase (Arg), inducible nitric oxide synthase (iNOS/NOS2), and indoleamine-2,3-dioxygenase (IDO). Prostaglandin E2 (PGE2), a mediator of chronic inflammation and tumor progression, has emerged as a key molecule in MDSC biology. PGE2 promotes MDSC development and their induction by additional factors, directly suppresses T cell immune responses and participates in the induction of other MDSC-associated suppressive factors, including Arg, iNOS and IDO. It further promotes MDSC recruitment to tumor environments through the local induction of CXCL12/SDF-1 and the induction and stabilization of the CXCL12 receptor, CXCR4, on tumor-associated MDSCs. The establishment of a positive feedback loop between PGE2 and cyclooxygenase 2 (COX-2), the key regulator of PGE2 synthesis, stabilizes the MDSC phenotype and is required for their suppressive function. The central role of PGE2 in MDSC biology provides for a feasible target for counteracting MDSC-mediated immune suppression in cancer. [ABSTRACT FROM AUTHOR]

The aim of present study was to evaluate antianxiety-like activity of gallic acid in Swiss young male albino mice; and to explore the possible underlying mechanisms for this activity. Gallic acid (5, 10, 20 mg/kg, i.p.) and alprazolam (0.25 mg/kg, i.p.) were administered for 10 successive days to separate groups of mice. On 10th day, 45 min after the drug administration, stress was produced by immobilization of mice for 150 min and these mice were called as stressed mice. Anxiolytic activity was evaluated using elevated plus maze and light-dark test. The plasma nitrite and corticosterone levels were also estimated in unstressed and stressed mice. Effects of 7-nitroindazole (neuronal NOS inhibitor) and aminoguanidine (inducible NOS inhibitor) on antianxiety-like activity of gallic acid were also evaluated. Gallic acid (10 and 20 mg/kg) and alprazolam per se significantly showed antianxiety-like activity in both unstressed and stressed mice. The drugs did not show any significant effect on locomotor activity of the mice. Gallic acid significantly decreased the plasma nitrite levels in both unstressed and stressed mice. 7-nitroindazole and aminoguanidine significantly enhanced antianxiety-like activity and plasma nitrite decreasing effect of gallic acid in unstressed and stressed mice respectively. Plasma corticosterone levels were significantly decreased by gallic acid in stressed mice as compared to its control. Thus, gallic acid showed antianxiety-like activity in unstressed mice probably by inhibition of nNOS. On the other hand, antianxiety-like activity in stressed mice might be through inhibition of iNOS and reduction of plasma corticosterone levels. [ABSTRACT FROM AUTHOR]

Background/Aims: Nonalcoholic fatty liver disease (NAFLD) is classically associated with insulin resistance and the inflammatory response, especially in the nonalcoholic steatohepatitis phase. The liver X receptors (LXRs) play a critical role in the regulation of cholesterol metabolism and inflammatory processes. Methods: Wild-type C57BL/6 mice were fed a normal diet (ND) or a high-fat (HF) diet for 8 weeks. Some ND- and HF-fed mice were treated (i.p.) with the LXR agonist T0901317 (30 mg/kg/day) for 7 days. Lipopolysaccharide (LPS, 50 μg/mouse) was then injected intraperitoneally to induce liver injury. The activation of MAPKs, NF-κB and the PI3K pathway was evaluated using Western blot. Bone marrow-derived macrophages (MDMs) were isolated from the femurs of C57BL/6 mice and cultured with or without T0901317 (20 μmol/l). The expression of tumor necrosis factor-alpha (TNF-α) and inducible nitric oxide synthase (iNOS) was evaluated in vitro or in vivo using real-time PCR, immunohistochemistry, or Western blot. Results: The LXR agonist T0901317 attenuated LPS-induced liver injury in a murine model of NAFLD, reflected by reduced serum alanine aminotransferase and aspartate aminotransferase levels, and reduced liver histology changes. Activation of LXRs reduced TNF-α and iNOS expression through inhibiting JNK and the PI3K signaling pathway. An in vitro study demonstrated that the activation of LXR inhibited the expression of TNF-α and iNOS in the MDMs of mice. Conclusions: Activation of LXRs attenuates LPS-induced liver injury in murine NAFLD through inhibiting the pro-inflammatory activity of macrophages. [ABSTRACT FROM AUTHOR]

Abstract: A series of oxadiazole derivatives containing 1,4-benzodioxan (4a–4s) have been first synthesized for their potential immunosuppressive activity. Among the compounds, compound 4i showed the most potent biological activity against RAW264.7 cells (inhibition=37.66±2.34% for NO overproduction and IC50 =0.05μM for iNOS). Docking simulation was performed to position compound 4i into the iNOS structure active site to determine the probable binding model. RT-PCR experiment results demonstrated that some of these compounds possessed good immunosuppressive activity against iNOS, especially for compound 4i. Therefore, compound 4i with potent inhibitory activity may be a potential agent. [Copyright &y& Elsevier]

Background: The contribution of nitric oxide (NO) to immune response and matrix degradation in the periodontal environment suggests a role for NO and NO-synthase (NOS) activity in the pathogenesis of cyclosporin A (CsA)-induced gingival overgrowth (GO). However, current knowledge on this topic is limited to experimental animal studies. The present study was undertaken on the basis of a hypothesis whether altered nitrite/nitrate levels in gingival crevicular fluid (GCF) and endothelial NOS (eNOS) and inducible NOS (iNOS) immunoreactivity in gingiva of CsA-treated patients contribute to the pathogenesis of CsA-induced GO. Methods: Twenty-four CsA-medicated renal transplant patients with GO (GO+; n = 12) or without GO (GO-; n = 12), 10 gingivitis, and 10 healthy subjects were included in the study. GCF samples from two proximal sites facing interdental papilla were collected, and papilla was excised, iNOS and eNOS were determined by immunohistochemistry. GCF nitrite/nitrate levels were analyzed based on the Griess reaction. Results: Weak iNOS immunostaining was observed in the healthy and GO- groups. In the gingivitis and GO+ groups, iNOS immunostaining significantly increased in connective tissue. Epithelial immunostaining of iNOS was localized to basal keratinocytes and the lower layer of stratum (str.) spinosum in the gingivitis group. In the GO+ group, iNOS immunostaining was differentially localized to keratinocytes of str. superficiale but considerably decreased in the str. basale. Weak eNOS immunostaining was found in the healthy and GO- groups, whereas higher immunostaining was observed in the gingivitis and GO+ groups. No intergroup differences were observed regarding nitrite/nitrate levels in GCF. Conclusion: CsA differentially upregulated iNOS, but not eNOS, in overgrown gingiva, which may play a pivotal role in the pathogenesis of CsA-induced GO. J Periodontol 2009;80:1638-1647. [ABSTRACT FROM AUTHOR]

Abstract: We have previously described a series of 3-phenyl-4,5-dihydro-1H-pyrazole derivatives as moderately potent nNOS inhibitors. As a follow up of these studies, several new 5-phenyl-1H-pyrrole-2-carboxamide derivatives have been synthesized, and their biological evaluation as in vitro inhibitors of both neural and inducible Nitric Oxide Synthase (nNOS and iNOS) is described. Some of these compounds show good iNOS/nNOS selectivity and the more potent compounds 5-(2-aminophenyl)-1H-pyrrole-2-carboxilic acid methylamide (QFF205) and cyclopentylamide (QFF212) have been tested as regulators of the in vivo nNOS and iNOS activity. Both compounds prevented the increment of the inducible NOS activity in both cytosol (iNOS) and mitochondria (i-mtNOS) observed in the MPTP model of Parkinson''s disease. [Copyright &y& Elsevier]

Abstract: Background: Activation of inducible nitric oxide synthase (iNOS) has been reported in congestive heart failure (CHF) conditions. However, it is unknown whether activation of iNOS affects prognosis of CHF patients. We prospectively studied the influence of activation of iNOS in the forearm on the outcome of CHF patients. Methods and Results: Forearm blood flow (FBF) responses to 3 doses of acetylcholine (ACh) and nitroglycerin (NTG), and 4 doses of a selective iNOS inhibitor (aminoguanidine: Amn) and a nonselective NOS inhibitor (L-NMMA) were examined using plethysmography in 68 patients with CHF from idiopathic dilated cardiomyopathy. Plasma brain natriuretic peptide (BNP) and tumor necrosis factor-α (TNF-α) were also measured in all patients. During the mean follow-up period of 3.8 years, 25 patients were hospitalized for worsening heart failure and 9 of these patients died. Patients with adverse events had a diminished vasodilator response to ACh (P < .001) compared to patients without adverse events. Amn significantly decreased FBF (P < .001) in patients with adverse events, but not in patients without adverse events. FBF responses to NTG and L-NMMA were not significantly different between the 2 groups. When grouped by maximum FBF responses to each drug above and below the median value, multivariate Cox proportional hazards model analyses for cardiac event showed a significance in the FBF response to Amn (adjusted hazard ratio 5.89, P < .001). FBF responses to maximum dose of Amn significantly correlated with BNP and TNF-α levels (both P < .001). Conclusions: CHF patients with vascular iNOS activation, as demonstrated by a greater vasoconstrictor response to Amn, had poor outcomes. Activation of iNOS in peripheral vessels, associated with proinflammatory cytokines in accordance to the severity of heart failure, is a marker for, or contributes to, adverse events in patients with CHF. [Copyright &y& Elsevier]

An elaborate network of highly inducible phase 2 proteins protects aerobic cells against the cumulative damaging effects of reactive oxygen intermediates and toxic electrophiles, which are the major causes of malignancy and chronic degenerative diseases. Many chemical and phytochemical agents, all of which react with thiol groups, induce the phase 2 response through their reactivity with critical cysteine thiols of Keapi. We recently found that the anti-inflammatory potencies (suppression of iNOS and COX-2 expression) of a series of triterpenoids with Michael reaction centers were closely correlated with the potencies of these agents to induce the phase 2 response. We now report that representatives of seven recognized chemical classes of inducers, including isothiocyanates, bisbenzylidenes, arsenicals, heavy metals, and vicinal dithiols, showed highly correlated inducer and anti-inflammatory potencies spanning more than six orders of magnitude of concentrations in established cells and in primary mouse peritoneal macrophages. Potency measurements were expressed as the D[subm] values (median effect concentration) by use of the Median Effect Equation. Whereas the phase 2 induction required the functional integrity of both the repressor Keapi and the transcription factor Nrf2, the effectiveness of inducers in blocking the up-regulation of iNOS by inflammatory cytokines was related to the nature of the cytokine and the inducer concentration. These studies identify suppression of inflammation as a consistent property of inducers of the phase 2 response and strongly suggest that this property is a central aspect of their chemoprotective actions. [ABSTRACT FROM AUTHOR]

The article presents on the effects of nitric oxide (NO) synthase inhibitors on cardiogenic shock (CS). According to mamalian research, CS accompanying myocardial infarction carries a case fatality rate related to a state of inflammatory storm accompanied by NO overproduction. The Phase III placebo controlled Study to Assess the Safety and efficacy of Tilarginine Acetate in CS trial demonstrated lack of clinical benefit of 5-h infusion of L-NMMA, an inhibitor of nitric oxide synthetase.

Abstract: Background: Cryopreservation is a valuable technique for storing heart valve and vascular allografts. However, the biological ramifications of cryopreservation are still unclear; therefore, using animal experiments we assessed how ‘cryopreservation’ influences graft allogenicity and cell viability. Methods: Thoracic aortas of Lewis rats were prepared as fresh (F) or cryopreserved (CP) grafts, and implanted into the infrarenal aorta of Lewis or Brown Norway rats (BNs). The grafts and spleens were harvested at post-operative day 7 and 28 (POD7, POD28) for analyses. Results: First, the systemic immune response to transplantation was estimated by mixed lymphocyte reaction analyses using spleen cells from naïve or recipient BNs. The alloreactivity of the recipients increased to 1.5 times that of the naïve BNs at POD7 and POD28, when stimulated by mitomycin C-treated Lewis spleen cells. Second, local immune response was estimated by TNFα, IFNγ, and iNOS mRNA expression in the grafts by quantitative PCR, which revealed 20- to 40-fold increases at POD28 after allotransplantation. Third, endothelial cell viability was estimated by endothelial NOS mRNA expression level: it was similar and highest in F and CP grafts before transplantation then significantly decreased after both syngeneic and allogeneic transplantation. Finally, intimal hyperplasia, expressed by I/M ratio, developed over time after allotransplantation, reaching 2.5 times the thickness of F grafts before transplantation. The results of these experiments revealed no difference between F and CP grafts before and after transplantation. Conclusion: Cryopreservation did not modify the allogenicity of vascular allografts and had minimal adverse impacts on graft cell viability. [Copyright &y& Elsevier]

Cerebral ischemia induces the expression of several growth factors and cytokines, which protect neurons against ischemic insults. Recent studies showed that granulocyte colony-stimulating factor (G-CSF) has a neuroprotective effect through the signaling pathway for the antiapoptotic cascade. The current study was designed to assess the neuroprotective mechanisms of G-CSF in ischemia/reperfusion injury using bone marrow chimera mice known to express enhanced green fluorescent protein (EGFP). Mice were subjected to ischemia/reperfusion and divided into two groups: those treated with G-CSF (G-CSF group) and vehicle (control group) (n=35 in each group). Immunohistochemistry and immunoblotting for antiapoptotic protein, nitrotyrosine, and inducible nitrate oxide synthase (iNOS) were performed. G-CSF significantly reduced stroke volume (34%, P<0.006). G-CSF upregulated Stat3, pStat3, and Bcl-2 (P<0.05), and suppressed iNOS and nitrotyrosine expression. In EGFP chimera mice, G-CSF decreased the migration of Iba-1/EGFP-positive bone marrow-derived monocytes/macrophages and increased intrinsic microglia/macrophages at ischemic penumbra (P<0.05), suggesting that bone marrow-derived monocytes/macrophages are not involved in G-CSF-induced reduction of ischemic injury size. Our study indicated that G-CSF exerts a neuroprotective effect through the direct activation of antiapoptotic pathway, and suggested that G-CSF is important for expansion of the therapeutic time window in patients with cerebral ischemia.Journal of Cerebral Blood Flow & Metabolism (2006) 26, 402–413. doi:10.1038/sj.jcbfm.9600195; published online 27 July 2005 [ABSTRACT FROM AUTHOR]

Administration of recombinant human erythropoietin (rhEPO) is known to induce protection against cardiac ischaemia injury improving functional recovery and reducing apoptosis. But the underlying mechanisms are not elucidated. We determined the role of nitric oxide synthases (NOS) as well as ATP-dependent (KATP) and calcium-activated (KCa) potassium channels in the early cardioprotection induced by rhEPO. Wistar male rats were divided into two experimental groups treated by rhEPO (5000 IU/kg, i.p.) or saline (control group). One hour later, rats were anaesthetized, hearts isolated, retrogradely perfused and submitted to a 30-min no-flow global ischaemia followed by 120 min of reperfusion sequence. Cardiac functional recovery (left ventricular developed pressure, LVDP) was significantly higher in the group treated by rhEPO (LVDP at 30 min reperfusion: 71.7 ± 2.3 mmHg) compared with the control group (57.4 ± 5.8 mmHg). We observed the same significant effect on its derivative (d P/d t). The rhEPO-induced improvement in ventricular function was abolished by perfusion prior to ischaemia with either N-nitro-l-arginine methyl ester (l-NAME, a nonspecific NOS inhibitor) or N-(3-(aminomethyl)benzyl)acetamidine (1400W, a specific inducible NOS inhibitor) or 5-hydroxydecanoic acid (5HD, a mitochondrial KATP channel blocker) but not with paxilline (a KCa channel inhibitor). Thus, in vivo rhEPO administration provides early preconditioning against ischaemic injury in the isolated perfused rat heart that is dependent on iNOS and mitochondrial KATP channels. [ABSTRACT FROM AUTHOR]

To study the role of endogenous NO in survival and recovery of spinal cord neurons after nerve lesions, wild type mice were compared to knock-out mice lacking neuronal, endothelial or inducible NO synthase (NOS) after sciatic nerve transection. The NO-generating capacities were assessed by NOS immunohistochemistry and NADPH-diaphorase staining. The feature of affected neurons was evaluated following Nissl- and TUNEL-staining, by immunocytochemical demonstration of cytochrome c-translocation, and by ultrastructural examination. Time point of cell loss was found to be independent of the mice type and occurred only at later post-axotomy states. The extent of neuronal degeneration, however, depended on the NO supply. Whereas a lack of endothelial or inducible NOS was well tolerated, deficiency of neuronal NOS enhanced the competence-to-die and led to a substantial apoptotic cell death of spinal cord neurons. Thus, NO supply turned out to be essential for cell survival and recovery with reference to the neuronal NOS isoform. [Copyright &y& Elsevier]

Objective: Antrochoanal polyp (ACP) is a polypoid lesion originating from the maxillary sinus, emerging from the ostium and extending to the choana. Although the etiologic causes of ACP are not known completely, it presents a fairly uniform clinical appearance. Nitric oxide (NO) has an important role in non-specific immunoreactions and inflammation in various tissues and has a main regulatory role in airway function and seems to involve in pathomechanism of several respiratory system diseases. NO is synthesized by the effect of three isoforms of nitric oxide synthase i.e. inducible NOS (iNOS). Some studies revealed that ACP has some different characteristics from the ordinary nasal polyps. In the present study, in order to compare ACP with allergic and non-allergic nasal polyps (NANP), we detected and localized the iNOS expression and also evaluate some histological parameters. Methods: Twenty-six cases were chosen from the files and four controls were used. The cases were separated as follows: normal inferior turbinate mucosa as control (n=4) ACPs (n=8), allergic nasal polyps (ANP) (n=9), and NANP (n=9). Five-micrometer thick sections were prepared from the paraffin sections of polyps and normal nasal mucosa to quantify the iNOS expression. iNOS protein was observed in the cytoplasm of epithelial and stromal inflammatory cells. iNOS protein expression in the groups was assessed according to the intensity of staining and histomorphological parameters, oedema, lymphocytic and eosinophilic cell infiltration were detected semi quantitatively. Results: iNOS expressions, either stromal or epithelial, were not different from each other among the four groups. Although it is not statistically significant, we noted that ANP and ACP frequently showed moderate and severe iNOS protein expression in epithelial and stromal parts when compared with NANPs and controls. Also, iNOS expression was significantly higher in the stroma of the ANPs than NANPs (P=0.012). Conclusions: ACPs and ANPs have frequently showed moderate and significant epithelial and stromal iNOS expression. Further studies are needed in large groups to elucidate differences between ACP and the other nasal polyps. [Copyright &y& Elsevier]

Developmental changes in the lung occur at birth, allowing for the transition from placental to air breathing. Here we have measured nitric oxide synthase (NOS) activity in the porcine lung pre and post partum. NOS activity, which was predominantly calcium dependent, was low in full term fetal tissue compared to that present in lungs from the newborn (5 minutes post partum), 1, 3, 6 and 14 day old animals. No increase in activity was seen when fetal pigs were allowed to breathe for 5 minutes. Specific activity remained low in fetal tissue following partial purification. By contrast, levels of NOS III protein in tissue extracts and in pulmonary arterial endothelial cells, demonstrated by immunohistochemistry, were similar in tissue from the fetal and newborn animals. Thus NOS activity is significantly lower in fetal when compared to postnatal lung tissue despite comparable amounts of NOS III protein being expressed, and birth is followed by an abrupt increase in enzyme activity in animals born at term which correlates with an increase in protein expression. [Copyright &y& Elsevier]

Nitric oxide (NO) is a small molecule produced by nitric oxide synthase (NOS) with various physio-pathological functions in the body. There are three main NOS isoforms, including the endothelial (eNOS), inducible (iNOS), and neuronal NOS (nNOS), that exist in the peripheral organs and nervous systems of humans and rodents. Moreover, NOS includes other identified NOS isoforms, such as retinal Muller glial cells (mNOS), mitochondrial (mtNOS), penile (PnNOS), testis-specific (TnNOS), and invertebrate Drosophila NOS (dNOS), which are the lesser-known types. It is proposed that the versatile functions of NOS isoforms depend on various NOS splice variant subtypes and their expression in the neural (e.g., brain, and spinal cord) and non-neuronal tissues (e.g., lung, kidney, liver, and GI tract). Therefore, this review summarizes the NOS subtypes, splice variants, targeted splicing expression in the body, and their proposed physio-pathological functions. At last, alternative NOS subtypes and isoforms, which have previously received scant attention, will be addressed in this article., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)