Formation of guanidinosuccinic acid, a stable nitric oxide mimic, from argininosuccinic acid and nitric oxide-derived free radicals

Pathogenesis of ventilator-induced lung injury: metabolomics analysis of the lung and plasma

INTRODUCTION

Nowadays,the mechanical ventilation (MV) aims to rest the respiratory muscles while providing adequate gas exchange, and it has been a part of basic life support during general anesthesia as well as in critically ill patients with and without respiratory failure. However, MV itself has the potential to cause or worsen lung injury, which is also known as ventilator-induced lung injury (VILI). Thus, the early diagnosis of VILI is of great importance for the prevention and treatment of VILI.

OBJECTIVE

This study aimed to investigate the metabolomes in the lung and plasma of mice receiving mechanical ventilation (MV).

METHODS

Healthy mice were randomly assigned into control group; (2) high volume tidal (HV) group (30 ml/kg); (3) low volume tidal (LV) group (6 ml/kg). After ventilation for 4 h, mice were sacrificed and the lung tissue and plasma were collected. The lung and plasma were processed for the metabolomics analysis. We also performed histopathological examination on the lung tissue.

RESULTS

We detected moderate inflammatory damage with alveolar septal thickening in the HV group compared with the normal and LV groups.The metabolomics analysis results showed MV altered the metabolism which was characterized by the dysregulation of γ-amino butyric acid (GABA) system and urea cycle (desregulations in plasma and lung guanidinosuccinic acid, argininosuccinic acid, succinic acid semialdehyde and lung GABA ), Disturbance of citric acid cycle (CAC) (increased plasma glutamine and lung phosphoenol pyruvate) and redox imbalance (desregulations in plasma and/or lung ascorbic acid, chenodeoxycholic acid, uric acid, oleic acid, stearidonic acid, palmitoleic acid and docosahexaenoic acid). Moreover, the lung and plasma metabolomes were also significantly different between LV and HV groups.

CONCLUSIONS

Some lung and plasma metabolites related to the GABA system and urea cycle, citric acid cycle and redox balance were significantly altered, and they may be employed for the evaluation of VILI and serve as targets in the treatment of VILI.

Metabolomics study of fibroblasts damaged by UVB and BaP

We have recently shown that both UVB and BaP can induce the production of ROS, apoptosis and even cancer. However, the differences in the metabolic profiles of skin damaged by UVB, BaP or UVB combined with BaP have not been studied. Therefore, we examined the metabolic changes in the human foreskin fibroblast injured by UVB or BaP or the combination of the two, using ultra performance liquid chromatography (UPLC) coupled with quadrupole time-of-flight mass spectrometry (qTOF-MS). 24 metabolites were altered in the UVB damage group, 25 in the BaP damage group, and 33 in the UVB combined with BaP group. These alterations indicated that the metabolic mechanisms of HFF-1 cells treated with UVB or BaP are related to multiple main metabolites including glycerophosphocholine (PC), lactosylceramide (LacCer), guanidinosuccinic acid (GSA), glutathione(GSH), and lysophosphatidylcholine (LysoPC) and the main mechanisms involved glycerophospholipid and glutathione metabolism. Thus, our report provided useful insight into the underlying mechanisms of UVB and BaP damage to skin cells.

Capillary Electrophoresis Mass Spectrometry-Based Metabolomics of Plasma Samples from Healthy Subjects in a Cross-Sectional Japanese Population Study

For large-scale metabolomics, such as in cohort studies, normalization protocols using quality control (QC) samples have been established when using data from gas chromatography and liquid chromatography coupled to mass spectrometry. However, normalization protocols have not been established for capillary electrophoresis-mass spectrometry metabolomics. In this study, we performed metabolome analysis of 314 human plasma samples using capillary electrophoresis-mass spectrometry. QC samples were analyzed every 10 samples. The results of principal component analysis for the metabolome data from only the QC samples showed variations caused by capillary replacement in the first principal component score and linear variation with continuous measurement in the second principal component score. Correlation analysis between diagnostic blood tests and plasma metabolites normalized by the QC samples was performed for samples from 188 healthy subjects who participated in a Japanese population study. Five highly correlated pairs were identified, including two previously unidentified pairs in normal healthy subjects of blood urea nitrogen and guanidinosuccinic acid, and gamma-glutamyl transferase and cysteine glutathione disulfide. These results confirmed the validity of normalization protocols in capillary electrophoresis-mass spectrometry using large-scale metabolomics and comprehensive analysis.

Free Radical Scavengers Prevent Argininosuccinic Acid-Induced Oxidative Stress in the Brain of Developing Rats: a New Adjuvant Therapy for Argininosuccinate Lyase Deficiency?

Tissue accumulation and high urinary excretion of argininosuccinate (ASA) is the biochemical hallmark of argininosuccinate lyase deficiency (ASLD), a urea cycle disorder mainly characterized by neurologic abnormalities, whose pathogenesis is still unknown. Thus, in the present work, we evaluated the in vitro and in vivo effects of ASA on a large spectrum of oxidative stress parameters in brain of adolescent rats in order to test whether disruption of redox homeostasis could be involved in neurodegeneration of this disorder. ASA provoked in vitro lipid and protein oxidation, decreased reduced glutathione (GSH) concentrations, and increased reactive oxygen species generation in cerebral cortex and striatum. Furthermore, these effects were totally prevented or attenuated by the antioxidants melatonin and GSH. Similar results were obtained by intrastriatal administration of ASA, in addition to increased reactive nitrogen species generation and decreased activities of superoxide dismutase, glutathione peroxidase, and glutathione S-transferase. It was also observed that melatonin and N-acetylcysteine prevented most of ASA-induced in vivo pro-oxidant effects in striatum. Taken together, these data indicate that disturbance of redox homeostasis induced at least in part by high brain ASA concentrations per se may potentially represent an important pathomechanism of neurodegeneration in patients with ASLD and that therapeutic trials with appropriate antioxidants may be an adjuvant treatment for these patients.

Argininosuccinate neurotoxicity and prevention by creatine in argininosuccinate lyase deficiency: An in vitro study in rat three-dimensional organotypic brain cell cultures

The urea cycle disorder (UCD) argininosuccinate lyase (ASL) deficiency, caused by a defective ASL enzyme, exhibits a wide range of phenotypes, from life-threatening neonatal hyperammonemia to asymptomatic patients, with only the biochemical marker argininosuccinic acid (ASA) elevated in body fluids. Remarkably, even without ever suffering from hyperammonemia, patients often develop severe cognitive impairment and seizures. The goal of this study was to understand the effect on the known toxic metabolite ASA and the assumed toxic metabolite guanidinosuccinic acid (GSA) on developing brain cells, and to evaluate the potential role of creatine (Cr) supplementation, as it was described protective for brain cells exposed to ammonia. We used an in vitro model, in which we exposed three-dimensional (3D) organotypic rat brain cell cultures in aggregates to different combinations of the metabolites of interest at two time points (representing two different developmental stages). After harvest and cryopreservation of the cell cultures, the samples were analyzed mainly by metabolite analysis, immunohistochemistry, and western blotting. ASA and GSA were found toxic for astrocytes and neurons. This toxicity could be reverted in vitro by Cr. As well, an antiapoptotic effect of ASA was revealed, which could contribute to the neurotoxicity in ASL deficiency. Further studies in human ASL deficiency will be required to understand the biochemical situation in the brain of affected patients, and to investigate the impact of high or low arginine doses on brain Cr availability. In addition, clinical trials to evaluate the beneficial effect of Cr supplementation in ASL deficiency would be valuable.

Metabolomics of Green-Tea Catechins on Vascular-Endothelial-Growth-Factor-Stimulated Human-Endothelial-Cell Survival

Neovascularization causes serious oculopathy related to upregulation of vascular-endothelial-growth factor (VEGF) causing new capillary growth via endothelial cells. Green-tea-extract (GTE) constituents possess antiangiogenesis properties. We used VEGF to induce human umbilical-vein endothelial cells (HUVECs) and applied GTE, epigallocatechin gallate (EGCG), and mixtures of different compositions of purified catechins (M1 and M2) to evaluate their efficacies of inhibition and their underlying mechanisms using cell-cycle analysis and untargeted metabolomics techniques. GTE, EGCG, M1, and M2 induced HUVEC apoptosis by 22.1 ± 2, 20.0 ± 0.7, 50.7 ± 8.5, and 69.8 ± 4.1%, respectively. GTE exerted a broad, balanced metabolomics spectrum, involving suppression of the biosynthesis of cellular building blocks and oxidative-phosphorylation metabolites as well as promotion of the biosynthesis of membrane lipids and growth factors. M2 mainly induced mechanisms associated with energy and biosynthesis suppression. Therefore, GTE exerted mechanisms involving both promotion and suppression activities, whereas purified catechins induced extensive apoptosis. GTE could be a more promising antineovascularization remedy for ocular treatment.

Daily sesame oil supplement attenuates joint pain by inhibiting muscular oxidative stress in osteoarthritis rat model

Osteoarthritis (OA) is the most common form of arthritis, affecting approximately 15% of the population. The aim of this study was to evaluate the efficacy of sesame oil in controlling OA pain in rats. Rat joint pain was induced by medial meniscal transection in Sprague-Dawley rats and assessed by using hindlimb weight distribution method. Muscular oxidative stress was assessed by determining lipid peroxidation, reactive oxygen species and circulating antioxidants. Sesame oil significantly decreased joint pain compared with positive control group in a dose-dependent manner. Sesame oil decreased lipid peroxidation in muscle but not in serum. Further, sesame oil significantly decreased muscular superoxide anion and peroxynitrite generations but increased muscular glutathione and glutathione peroxidase levels. Further, sesame oil significantly increased nuclear factor erythroid-2-related factor (Nrf2) expression compared with positive control group. We concluded that daily sesame oil supplement may attenuate early joint pain by inhibiting Nrf2-associated muscular oxidative stress in OA rat model.

Highly variable chemical signatures over short spatial distances among Scots pine (Pinus sylvestris) populations

Understanding within-species variability in terpenoid content and composition is highly relevant for predicting species adaptive potential to biotic stresses, but there is still limited information on terpene variations even for widespread species. We studied the foliage content and composition of terpenoids, foliage structure, and carbon (C) and nitrogen (N) contents in Pinus sylvestris L. in four Estonian sites ranging from dry forest to raised bog. In the bogs, samples were taken along the environmental gradient from drier margins towards wetter central parts. A chiral column was used to gain insight into the variation in terpene composition. We hypothesized that terpene contents increase and the composition becomes more diverse in more strongly N-limited sites (greater C/N ratio) and that terpene signatures cluster together in sub-sites with similar conditions (drier/wetter). Altogether 37 terpenes were quantified across the sites. Extremely large variability of terpene contents, 48-62% for monoterpenes and 61-89% for sesquiterpenes, was observed. According to the amounts of α-pinenes and (+)-3-carene, we distinguished two different 'pine chemotypes'. Contrary to the hypothesis, terpene contents and variability were the greatest in the dry site with the lowest C/N ratio. However, individual terpenoids correlated differently with C or N in different sites, indicating site effects on terpene composition. Moreover, correlations between the terpenoids and C or N depended on the pine chemotype. The sub-sites with different water regime were more strongly clustered together within the site than across the sites. The study demonstrates extensive variations in terpene contents and composition among the populations and over short spatial distances within the populations, suggesting a large among- and within-population adaptive capacity of P. sylvestris.

Protective effect of daily sesame oil supplement on gentamicin-induced renal injury in rats

Gentamicin, an aminoglycoside antibiotic, is widely used in the treatment of Gram-negative infections; however, dose-limiting nephrotoxicity restricts its optimal use. We investigated the effect of a daily sesame oil supplement on oxidative-stress-associated renal injury induced by a single daily dose of gentamicin in rats. Renal injury was induced by a single subcutaneous daily dose of gentamicin (100 mg kg(-1) d(-1) for 7 days), and then the effects of oral sesame oil (0.25, 0.5, and 1 mL kg(-1) d(-1) for 7 days) on renal injury, oxidative stress, hydroxyl radical, superoxide anion, and NO were assessed after treatment. Sesame oil inhibited gentamicin-induced renal injury, lipid peroxidation, hydroxyl radical, and superoxide anion, as well as NO production. In addition, sesame oil inhibited xanthine oxidase activity and inducible NOS expression in gentamicin-challenged rats. We hypothesize that a daily sesame oil supplement attenuates oxidative-stress-associated renal injury by reducing oxygen free radicals and lipid peroxidation in gentamicin-treated rats.

Hereditary urea cycle diseases in Finland

AIM

To estimate the incidence of urea cycle diseases (UCDs) in Finland and determine the course of the various disorders as well as the outcome.

METHODS

The original data were collected in the years 1998-2001. The diagnoses made after 2001, as well as the current status of the patients, were updated by surveys in the spring of 2007.

RESULTS

We found a total of 55 cases of UCDs in Finland by 2007: 30 cases of ornithine transcarbamylase (OTC) deficiency, 20 of argininosuccinate lyase (ASL) deficiency, 3 of carbamyl phosphate synthetase (CPS-I) deficiency, 1 of type 1 citrullinaemia and 1 of argininaemia. The estimated total incidence of UCDs was 1:39 000. The incidences of individual disorders were: OTC deficiency 1:62 000, ASL deficiency 1:144 000, CPS deficiency 1:539 000 and citrullinaemia 1:1 616 000. Eighteen (33%) of the patients with a diagnosis of UCD have died, most during their first hyperammonaemic crisis. One patient with OTC deficiency has had a liver transplant. Neurological symptoms of varying severity are common among these patients, particularly those with ASL deficiency.

CONCLUSION

The first survey on the incidence of UCDs in Finland shows some differences in the occurrence rates compared to other countries. Hyperammonaemia, and the neurological symptoms caused by it, can be avoided in most patients with late-onset UCDs with a standard treatment. However, in patients with ASL deficiency, the development of neurological symptoms seems to be inevitable in spite of careful treatment and avoidance of hyperammonaemia.

The prophylactic protective effect of sesamol against ferric-nitrilotriacetate-induced acute renal injury in mice

The aim of this study was to examine the prophylactic protective effects of 3,4-methylenedioxyphenol (sesamol) on ferric-nitrilotriacetate (Fe-NTA)-induced acute renal damage in mice. We induced acute renal injury in mice by treating them with 4 mg/kg of Fe-NTA for 3h. We used blood biochemistry, creatinine clearance, and histological examinations to assess renal function. With a high-performance chemiluminescence analyzer, we also determined the hydroxyl radical and superoxide anion levels (free radicals) generated. Renal xanthine oxidase activities were also assessed. Sesamol inhibited Fe-NTA-induced acute renal injury, renal lipid peroxidation, the levels of renal hydroxyl radical and superoxide anion generated, and the activity of xanthine oxidase in mice. Therefore, we concluded that sesamol protected mice against Fe-NTA-induced oxidative-stress-associated acute renal injury by at least partially inhibiting the production of reactive oxygen species.

SESAME OIL ATTENUATES CISPLATIN-INDUCED HEPATIC AND RENAL INJURIES BY INHIBITING NITRIC OXIDE-ASSOCIATED LIPID PEROXIDATION IN MICE

Although cisplatin (cis-diamminedichloroplatinum) is an effective drug for the treatment of several solid tumors and has been used therapeutically for decades, several cisplatin-induced side effects have limited its therapeutic dosage in clinical studies. Our aim was to examine the effect of sesame oil on cisplatin-induced hepatic and renal injuries in mice (8-week-old female SPF C57BL/6) given subcutaneous cisplatin (0, 5, 10, or 20 mg/kg). Hepatic and renal functions, lipid peroxidation (LPO) levels, and reactive oxygen free radicals were evaluated 3 days after cisplatin administration, and tumor volumes were recorded 0, 3, 6, and 9 days after cisplatin administration. Sesame oil (i) potently attenuated cisplatin-associated hepatic and renal injuries; (ii) decreased cisplatin-initiated LPO as well as the production of hydroxyl radical, peroxynitrite, and nitrite in blood and tissue; and (iii) did not affect the antitumor capacity exerted by cisplatin in mice with melanoma. We suggest that sesame oil attenuates cisplatin-induced hepatic and renal damage by at least partially inhibiting nitric oxide-associated LPO in mice. Sesame oil might be a new approach for preventing cisplatin-induced multiple organ injury during the treatment of tumors.

Sesamol delays mortality and attenuates hepatic injury after cecal ligation and puncture in rats: role of oxidative stress

Sesame oil potently protects rats against sepsis, and sesamol appears to be the protective ingredient in sesame oil. The aims of the present study were to examine the effects of sesamol on mortality and reactive oxygen species-associated liver injury in Wistar rats with cecal-ligation-and-puncture-induced sepsis (septic rats). After sepsis was induced, sesamol was administered every 6 h. The survival rate was determined during the ensuing 48 h. Hepatic injury was assessed using blood biochemistry and histological examination. Hepatic oxidative stress was assessed by determining the levels of liver lipid peroxidation, hydroxyl radical, and superoxide anion generation, and nitric oxide production 12 h after cecal ligation and puncture. Inducible nitric oxide synthase expression was also determined. Sesamol delayed mortality and attenuated hepatic injury in septic rats. Hepatic lipid peroxidation, hydroxyl radical, and superoxide anion levels were significantly lower in sesamol-treated septic rats. Furthermore, sesamol inhibited the production of nitrite and the expression of inducible nitric oxide synthase in the liver in septic rats. Therefore, sesamol may delay mortality and attenuate oxidative stress-associated liver injury by inhibiting the production of nitric oxide, at least partially, in septic rats.

ATTENUATION OF ENDOTOXIN-INDUCED OXIDATIVE STRESS AND MULTIPLE ORGAN INJURY BY 3,4-METHYLENEDIOXYPHENOL IN RATS

Endotoxin is a potent inducer of lipid peroxidation (LPO), which is associated with the development of endotoxemia. 3,4-Methylenedioxyphenol (sesamol) is one of the sesame oil lignans with a high anti-LPO effect. Whether sesamol can attenuate endotoxin-induced LPO and multiple organ injury is unknown. After a dose response for sesamol in endotoxin-challenged rats was established, experiments were conducted to assess its effects on hydroxyl radical, peroxynitrite, and superoxide anion counts, activities of superoxide dismutase, catalase, and glutathione peroxidase, as well as the production of nitric oxide (NO) and the expression of inducible NO synthase. In addition, the effects of sesamol on endotoxin-induced hepatic and renal injuries were assessed. Sesamol (a) dose dependently reduced serum LPO inendotoxin-challenged rats, (b) decreased hydroxyl radical and peroxynitrite, but not superoxide anion counts, (c)increased the activities of superoxide dismutase, catalase, and glutathione peroxidase in endotoxin-treated rats, (d)reduced NO production and inducible NO synthase expression, and (e) attenuated hepatic and renal injuries induced by endotoxin in rats. We concluded that sesamol might protect against organ injury by decreasing NO-associated LPO in endotoxemic rats.

BICUCULLINE METHIODIDE ATTENUATES HEPATIC INJURY AND DECREASES MORTALITY IN SEPTIC RATS: ROLE OF CYTOKINES

Bicuculline methiodide attenuates inflammation by inhibiting the production of proinflammatory cytokines, such as tumor necrosis factor-alpha, and by increasing the production of the anti-inflammatory cytokine interleukin-10, both of which play important roles in the pathogenesis of sepsis. The aim of this study was to examine the effects of bicuculline methiodide on sepsis in the cecal ligation and puncture septic-rat model. Cytokine production was measured by enzyme-linked immunosorbent assay. Oxidative stress was assessed by determining serum lipid peroxidation and nitrite levels. Hepatic injury was evaluated by determining the levels of serum aspartate aminotransferase, alkaline phosphatase, and total bilirubin. Mortality was recorded within 24 h. Bicuculline methiodide potently decreased the production of tumor necrosis factor-alpha and interleukin-1beta but increased interleukin-10 in serum. Bicuculline methiodide significantly decreased serum lipid peroxidation and nitrite levels. Further, bicuculline methiodide attenuated hepatic injury and reduced mortality after cecal ligation and puncture. Therefore, the alteration of cytokine production may be involved in the effects of bicuculline methiodide on hepatic injury and mortality in septic rats.

Low water-soluble uremic toxins

The uremic syndrome is the result of the retention of solutes, which under normal conditions are cleared by the healthy kidneys. Uremic retention products are arbitrarily subdivided according to their molecular weight. Low-molecular-weight molecules are characterized by a molecular weight below 500 D. The purpose of the present publication is to review the main water soluble, nonprotein bound uremic retention solutes, together with their main toxic effects. We will consecutively discuss creatinine, glomerulopressin, the guanidines, the methylamines, myo-inositol, oxalate, phenylacetyl-glutamine, phosphate, the polyamines, pseudouridine, the purines, the trihalomethanes, and urea per se.

Parenteral sesame oil attenuates oxidative stress after endotoxin intoxication in rats

Sesame oil is regarded as a daily nutritional supplement to increase cell resistance to lipid peroxidation. The aims of this study were to examine the effects of parenteral sesame oil on oxidative stress and hepatic disorder induced by lipopolysaccharide and to determine the defense mechanisms involved in sesame oil-associated anti-oxidative effects in rats. Oxidative stress was induced by lipopolysaccharide (5 mg/kg, intraperitoneally) and assessed by determination of lipid peroxidation. Sesame oil (8 ml/kg, subcutaneously) was given 3 h after lipopolysaccharide, and lipid peroxide levels, hydroxyl radical, superoxide anion, the enzyme activities of superoxide dismutase and catalase as well as the levels of glutathione and nitrite were examined 6 h after lipopolysaccharide. Hepatic function was assessed by determining the activities of serum aspartate aminotransferase and alkaline phosphatase. Sesame oil reduced lipid peroxidation and hydroxyl radical, but failed to affect superoxide anion. Superoxide dismutase and catalase were increased, but glutathione was not affected, and the levels of nitrite were reduced. Further, sesame oil-treated groups showed attenuated hepatic disorder in lipopolysaccharide-treated rats. Thus, parenteral sesame oil can be used to attenuate oxidative stress and relieve hepatic disorder after lipopolysaccharide intoxication in rats.

Nitric oxide in uremia: effects of several potentially toxic guanidino compounds

Vascular and neurologic impairment remain an important source of morbidity in patients with chronic renal failure (CRF). A portion of CRF patients still suffers from uremic encephalopathy or other signs of nervous system impairment. Several reports demonstrate increased incidence of cardiac infarction and cerebrovascular accidents in CRF patients, even in those with otherwise adequate dialysis treatment [1]. Premature vascular disease, including myocardial infarction, stroke, and peripheral vascular disorder, are the leading causes of death in this population. Although several traditional risk factors for vascular disease and endothelial dysfunction, including smoking, diabetes, dyslipidemia, and hypertension, are often increased in CRF, these factors can only partly explain the high vasculopathy-related morbidity and mortality. Several authors have postulated that CRF-associated atherosclerosis and endothelial dysfunction result from accumulation of certain 'uremic factors,' the identities of which are still a matter of debate. These factors include a variety of guanidino compounds (GCs), which have been shown to be nitric oxide synthase (NOS) modulators both in vitro and in vivo. However, other effects of accumulated uremic GCs have been identified.

Overexpression of arginase alters circulating and tissue amino acids and guanidino compounds and affects neuromotor behavior in mice

Arginine is an intermediate of the ornithine cycle and serves as a precursor for the synthesis of nitric oxide, creatine, agmatine and proteins. It is considered to be a conditionally essential amino acid because endogenous synthesis only barely meets daily requirements. In rapidly growing suckling neonates, endogenous arginine biosynthesis is crucial to compensate for the insufficient supply of arginine via the milk. Evidence is accumulating that the intestine rather than the kidney plays a major role in arginine synthesis in this period. Accordingly, ectopic expression of hepatic arginase in murine enterocytes by genetic modification induces a selective arginine deficiency. The ensuing phenotype, whose severity correlates with the level of transgene expression in the enterocytes, could be reversed with arginine supplementation. We analyzed the effect of arginine deficiency on guanidine metabolism and neuromotor behavior. Arginine-deficient transgenic mice continued to suffer from an arginine deficiency after the arginine biosynthetic enzymes had disappeared from the enterocytes. Postweaning catch-up growth in arginine-deficient mice was characterized by increased levels of all measured amino acids except arginine. Furthermore, plasma total amino acid concentration, including arginine, was significantly lower in adult male than in adult female transgenic mice. Decreases in the concentration of plasma and tissue arginine led to significant decreases in most metabolites of arginine. However, the accumulation of the toxic guanidino compounds, guanidinosuccinic acid and methylguanidine, corresponded inversely with circulating arginine concentration, possibly reflecting a higher oxidative stress under hypoargininemic conditions. In addition, hypoargininemia was associated with disturbed neuromotor behavior, although brain levels of toxic guanidino compounds and ammonia were normal.

Decolorization of synthetic dyes by the Fenton reagent and the Cu/pyridine/H2O2 system

Representative azo, triphenylmethane, heterocyclic and polymeric synthetic dyes have been decolorized by two biological non-ezymatic systems, copper/pyridine/H2O2 and the Fenton reagent. With the former system, intensive decolorization measured after 1 h was obtained with phenol red (89%), tropaeolin 00 (58%), Evans blue (95%), eosin yellowish (84%), and Poly B-411 (92%). The rate of decolorization was not affected by pH in the range of 3-9 and increased with increasing temperature. The use of the radical scavengers thiourea and superoxide dismutase showed that hydroxyl radicals rather than superoxide anions are involved in the reaction. Omission of pyridine led to a substantial decrease in the extent of decolorization (20-50% decolorization). The use of organic peroxide instead of H2O2 resulted in slightly slower decolorization, similar values of decolorization being obtained only after a 2-h incubation. Decolorization of the dyes by the Fenton reagent was also very effective but slower than that obtained with the first system. Except for phenol red and eosin yellowish, (decolorization 8% and 52%, respectively) the dyes were decolorized up to 99% after 1-day incubation.

Differential cardiovascular responses to blockade of nNOS or iNOS in rostral ventrolateral medulla of the rat

We investigated the contribution of neuronal or inducible nitric oxide synthase (nNOS or iNOS) at the rostral ventrolateral medulla (RVLM) to central cardiovascular regulation by endogenous nitric oxide (NO), using Sprague-Dawley rats anaesthetized and maintained with propofol. Microinjection bilaterally into the RVLM of a NO trapping agent, carboxy-2-phenyl-4,4,5,5-tetramethylimidazoline-l-oxy-l-3-oxide (10, 50 or 100 nmoles) resulted in significant hypotension and bradycardia. Similar application of a selective antagonist of nNOS, 7-nitroindazole (1, 2.5 or 5 pmoles), or selective antagonists of iNOS, aminoguanidine (125, 250 or 500 pmoles), N(6)-(l-iminoethyl)-L-lysine (250 pmoles) or S-methylisothiourea (250 pmoles), induced respectively a reduction or an enhancement in systemic arterial pressure, heart rate and power density of the vasomotor components in the spectrum of arterial blood pressure signals, the experimental index for sympathetic neurogenic vasomotor tone. Both hypotension and bradycardia induced by the NO precursor, L-arginine (100 nmoles), were significantly blunted when aminoguanidine (250 pmoles) was co-microinjected bilaterally into the RVLM. On the other hand, co-administered 7-nitroindazole (2.5 pmoles) was ineffective. Whereas low doses of S-nitro-N-acetylpenicillamine (0.25 or 0.5 nmoles) elicited hypertension and tachycardia, high doses of this non-nitrate NO donor (5 nmoles) induced hypotension and bradycardia. Reverse transcription - polymerase chain reaction analysis revealed that both iNOS and nNOS mRNA were expressed in the ventrolateral medulla. We conclude that the prevalence of nNOS over iNOS activity at the RVLM and the associated dominance of sympathoexcitation over sympathoinhibition may underlie the maintenance of sympathetic vasomotor outflow and stable systemic arterial pressure by the endogenous NO.