Antioxidative Propolis From Stingless Bees (Heterotrigona Itama) Preserves Endothelium-Dependent Aortic Relaxation of Diabetic Rats: The Role of Nitric Oxide and Cyclic Guanosine Monophosphate

Propolis from stingless bees (Heterotrigona itama) is a resinous compound that exhibits antihyperglycaemia, free radical scavenging, and cardioprotective properties. The effect of propolis on diabetic vessels has not been investigated. Thus, this research aimed to determine the effect of propolis supplementation on the level of antioxidants and its mechanism of action in the aorta of diabetic rats. Male Sprague-Dawley rats were divided into five groups (n=8/group): healthy (control), untreated diabetes (DM), metformin-treated diabetes (DM+M, 300 mg/kg/day metformin), propolis-treated diabetes (DM+P, 300 mg/kg/day propolis extract) and diabetes with combined treatment (DM+M+P, dosage as former). Oral supplementation was conducted for four weeks immediately upon successful induction of diabetes by streptozotocin (60 mg/kg, intraperitoneal injection). At the end of the study, the rats were euthanised, and thoracic aorta was processed into tissue homogenates to determine the levels of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase-1 (GPx-1) and soluble receptor for advanced glycation end-products (sRAGE). Aorta segments were harvested to examine their relaxation response towards graded concentration of acetylcholine (Ach; 10-8-10-4) M following precontraction with phenylephrine (PE; 10-6 M). Vasorelaxation towards a cumulative dose of propolis (0.01-1.00%) using PE-precontracted healthy aorta (n=6/experiments) was investigated under various simulated conditions: physiological buffer, L-NAME (10-4 M), methylene blue (10-5 M), indomethacin (10-5 M) and elevated glucose (25 mM). Propolis maintained antioxidative enzymes and sRAGE decoy molecules in the aortic tissue of the diabetic rats. The amelioration of diabetes-induced impairment of endothelium-dependent relaxation by propolis was mediated through the nitric oxide(NO)-cyclic guanosine monophosphate (cGMP) pathway. This non-clinical study reports vasoprotective property of propolis in diabetes mellitus.

Improving risk assessment approaches for chemicals with both endogenous and exogenous exposures.

To conduct risk assessments of exogenous chemicals for which there are also endogenous exposures, knowledge of the chemistry and biology of both types of exposures needs to be integrated into problem formulation and carried through to risk characterization. This issue is framed in a risk assessment context, highlighting the importance of quantifying increments of dose from all sources of the same or similar chemicals interacting with biological targets; understanding the influence of endogenous chemical concentrations on disease risk; and assessing total dose to targets in evaluating risk from incremental environmental exposures. Examples of recent assessments illustrate the importance of addressing this issue. Evaluations of data on blood or organ concentrations of ammonia, methanol, formaldehyde, acetaldehyde, and three gaseous signaling molecules (hydrogen sulfide, carbon monoxide, and nitric oxide) provide examples where current data are already informing perspectives on relative exposures at the portal of entry and systemically. To facilitate quality risk assessments of exogenous chemicals with endogenous exposures, a series of specific questions are presented that need to be addressed in systematic review to enhance problem formulation, improve the development of holistic conceptual models, and to facilitate the identification of priority data needs for improving risk assessments.

Does l-glutamine-supplemented diet extenuate NO-mediated damage on myenteric plexus of Walker 256 tumor-bearing rats?

This study was designed to appraise the relationship between enteric neuropathy and oxidative stress in cancer cachexia under l-glutamine-supplemented diet. Total and nitrergic neuronal populations were investigated in jejunum and ileum in four experimental groups: control (C); control l-glutamine-supplemented diet (CG); Walker-256 tumor (TW); and Walker-256 tumor supplemented with l-glutamine (TWG). In addition, local oxidative stress, neuronal nitric oxide synthase (nNOS) enzyme and nitric oxide (NO) levels were evaluated. Neuronal density and somatic area of the total and nitrergic populations were reduced in TW rats, which was accompanied by high oxidative stress, NO and nNOS levels. l-glutamine supplementation prevented neuronal atrophy, changes in pan neuronal density and nNOS overexpression (ileum), and restored total antioxidant capacity. Nevertheless, the oxidative stress was partially mitigated and no effect was observed on the reduction of nitrergic population and NO levels. l-glutamine-supplemented diet extenuates NO-mediated damage on the myenteric plexus although has a small benefit on oxidative stress.

[ERGOGENIC SPORT SUPPLEMENTS FOR ATHLETES].

Use of performance-enhancing supplements occurs at all levels of sports, from recreational athletes to professional athletes. Although some supplements do enhance athletic performance, many have no proven benefits and have adverse effects. Nutritional supplements are categorized into the following categories: I. Apparently Effective. II. Possibly Effective. III. Too Early To Tell. IV. Apparently Ineffective. This article will review 4 ergogenic supplements which are categorized in the first category--"Apparently Effective"--1) Buffer agents 2) Creatine 3) Caffeine and 4 Nitric Oxide. Given the widespread use of performance enhancing supplements, physicians, and dietitians should be prepared to counsel athletes about their effectiveness, safety and legality.

Tartary buckwheat on nitric oxide-induced inflammation in RAW264.7 macrophage cells.

We investigated the effects of tartary buckwheat (TB, Fagopyrum tataricum) on the production of pro-inflammatory mediators in lipopolysaccharide (LPS)- and interferon (IFN)-γ-stimulated RAW264.7 cells. We evaluated the anti-inflammatory effects of TB against the LPS- and IFN-γ-stimulated inflammatory response in RAW264.7 macrophage cells. We fractionated TB to obtain 4 fractions including the n-hexane, methylene chloride, ethyl acetate (EtOAc), and n-butanol fractions. In addition, rutin was isolated and identified from the EtOAc fraction. The 4 fractions and rutin effectively inhibited the production of reactive oxygen species, nitric oxide (NO), and interleukin-6. In addition, the mRNA expression levels of pro-inflammatory factors including nuclear factor kappa B, cyclooxygenase-2, and inducible NO synthase were down-regulated in LPS- and IFN-γ-stimulated RAW264.7 cells following treatment with the 4 fractions and rutin. The present study suggests that TB could induce anti-inflammation by regulating the expression of inflammatory mediators.

Renal failure in a soldier taking N.O.-Xplode.

INTRODUCTION: Dietary supplements are widely used but are unregulated by the US Food and Drug Administration. Presented here is a case of severe renal failure possibly associated with a dietary supplement, which demonstrates the need for improved patient-physician communication regarding the possible risks and lack of regulation of dietary supplements. METHODS: A 26-year-old man presented with 3 days of flank pain. The patient had been taking a dietary supplement called N.O.-Xplode for 3 months. Initial laboratory tests revealed a creatinine value of 9.45 mg/dL. Extensive laboratory analysis and imaging revealed no underlying cause of his renal injury. Renal biopsy showed acute tubular necrosis with normal glomeruli. After discontinuing N.O.-Xplode, renal function returned to normal within 1 week. CONCLUSIONS: This case demonstrates the need for improved patient-physician communication about dietary supplements. The patient had not consulted a physician before initiating use; the amount of each ingredient contained in the dietary supplement is unavailable; and there are no available data regarding safety or efficacy. It is critical that physicians are able and open to counseling patients on the inherent risks associated with dietary supplements, including their lack of regulation by the Food and Drug Administration, unknown efficacy, and possible serious adverse outcomes.

Interactions among chemical components of Cocoa tea (Camellia ptilophylla Chang), a naturally low caffeine-containing tea species.

In the 1980s, a novel tea species, Cocoa tea (Camellia ptilophylla Chang), was discovered in Southern China with surprisingly low caffeine content (0.2% by dry weight). Although its health promoting characteristics have been known for a while, a very limited amount of scientific research has been focused on Cocoa tea. Herein, a systematic study on Cocoa tea and its chemical components, interactions and bioactivities was performed. YD tea (Yunnan Daye tea, Camellia sinensis), a tea species with a high caffeine content (5.8% by dry weight), was used as a control. By UV-Vis spectrometry, High Performance Liquid Chromatography (HPLC), and Flame Atomic Absorption Spectrometry (FAAS) for chemical composition analysis, C-2 epimeric isomers of tea catechins and theobromine were found to be the major catechins and methylxanthine in Cocoa tea, respectively. More gallated catechins, methylxanthines, and proteins were detected in Cocoa tea compared with YD tea. Moreover, the tendency of major components in Cocoa tea for precipitation was significantly higher than that in YD tea. Catechins, methylxanthines, proteins, iron, calcium, and copper were presumed to be the origins of molecular interactions in Cocoa tea and YD tea. The interactions between catechins and methylxanthines were highly related to the galloyl moiety in catechins and methyl groups in methylxanthines. In vitro anti-inflammatory activity assays revealed that Cocoa tea was a more potent inhibitor of nitric oxide (NO) in lipopolysaccharide (LPS)-stimulated macrophage cells (RAW 264.7) than YD tea. This study constructs a solid phytochemical foundation for further research on the mechanisms of molecular interactions and the integrated functions of Cocoa tea.

Inibição da expressão de ciclooxigenase 2 em feridas cutâneas de camundongos NOD submetidos à terapia a laser de baixa intensidade / Inhibition of cyclooxygenase 2 expression in NOD mice cutaneous wound by low-level laser therapy

CONTEXTO: A terapia a laser de baixa intensidade (LLLT) tem sido relatada como importante moduladora da cicatrização de feridas cutâneas aumentando a proliferação fibroblástica associada ao aumento da expressão da citocina fator transformador de crescimento- β2 (TGF-βB2). OBJETIVO: No presente estudo foram avaliados os efeitos da LLLT sobre a expressão da enzima ciclooxigenase 2 (COX2) no sítio do reparo tecidual utilizando o modelo experimental com camundongos diabéticos não obesos (NOD) para estudar a cicatrização de feridas cutâneas. MÉTODOS: Foram utilizados 30 camundongos NOD, destes 14 ficaram diabéticos e foram divididos em dois grupos: o grupo I (n=7) foi submetido a um procedimento cirúrgico de feridas cutâneas e o grupo II (n=7) foi submetido a um procedimento cirúrgico de feridas cutâneas e tratados com LLLT. O grupo II foi submetido à LLLT nos seguintes parâmetros: 15 mW de potência, dose de 3,8 J/cm² e tempo de aplicação de 20 segundos. Após sete dias do ato cirúrgico e após aplicação do laser, os animais foram eutanasiados com sobredose de anestesia e amostras das feridas foram colhidas para posterior análise histopatológica, histomorfométrica e imuno-histoquímica. RESULTADOS: A LLLT promoveu a inibição da expressão da COX2 em feridas cutâneas de camundongos diabéticos. CONCLUSÃO: Em conjunto, os resultados sugeriram que a LLLT é capaz de modular negativamente a expressão da enzima COX2 contribuindo para o controle da resposta inflamatória em feridas cutâneas de camundongos NOD.

BACKGROUND: Low-level laser therapy (LLLT) has been reported to modulate the healing of wounds by inducing an increase in fibroblast number associated with increased expression of the cytokine transforming growth factor-β2 (TGF-β2). OBJECTIVE: In the present study, the effect of LLLT on expression of COX2 at the site of tissue repair was evaluated, using an experimental model with non obese diabetic mice (NOD) to study cutaneous wound healing. METHODS: Thirty NOD mice were used, of which 14 were diabetic and were divided into two groups: group I (n=7) underwent a surgical procedure of skin wounds and group II (n=7) underwent a surgical procedure of skin wounds and treated with LLLT. Group II was submitted to LLLT in the following parameters: 15 mW of power, dose of 3.8 J/cm² and exposure time of 20 seconds. Seven days after surgery and after laser application, animals were euthanized with an overdose of anesthesia and tissue samples were collected for subsequent histological analysis, histomorphometry and immunohistochemistry. RESULTS: The LLLT has promoted the inhibition of COX2 expression in skin wounds in mice diabetic. Taken together the results suggest that LLLT modulate the expression of COX2 improved the control of inflammatory reaction in cutaneous wound lesions in NOD mice. CONCLUSION: Taken together, the results suggested that LLLT is able to negatively modulate the expression of COX2 enzyme contributing to the inflammatory response in cutaneous wounds in NOD mice.

Inhaled nitric oxide therapy fails to improve outcome in experimental severe influenza.

In vitro, nitric oxide (NO) has been shown to have antimicrobial activity against a wide range of viruses, including influenza A virus. Therefore, we hypothesized that inhaled nitric oxide (iNO) would increase survival in vivo by reducing the viral load in C57Bl/6 mice infected with a lethal dose of influenza A/WSN/33 (H1N1; WSN/33) virus. NO was delivered to influenza-infected mice either continuously or intermittently at 80 or 160 ppm, respectively, using both prophylactic and post-infection treatment strategies. Murine survival and weight loss were assessed, and lung viral load was quantified via plaque assay. Here, we report that iNO administered prophylactically or post-influenza infection failed to improve survival of infected mice. No difference in lung viral load was observed between experimental groups. Although NO has antiviral activity against influenza A virus in vitro, iNO therapy provided no apparent benefit when used for treatment of influenza A virus infection in vivo.

Early involvement of nitric oxide in mechanisms of pathogenesis of experimental autoimmune uveitis induced by interphotoreceptor retinoid-binding protein (IRBP).

INTRODUCTION: Autoimmune uveitis is a group of HLA-associated inflammatory diseases of the eye, prevalent worldwide, that may cause blindness. It can be limited to the eye, or associated with a systemic syndrome. Furthermore, patients suffering from uveitis exhibit high serum and local nitric oxide (NO) levels as a consequence of cellular responses to immunologically privileged antigens within the eye such as interphotoreceptor retinoid binding protein (IRBP). To investigate NO production kinetics in autoimmune uveitis and its implication in mechanisms of ocular pathogenesis, we first attempted to develop an experimental model of autoimmune uveitis (EAU) on the Wistar rat, using the whole bovine retinal interphotoreceptor matrix extract (IPMe) and isolated IRBP. MATERIAL AND METHODS: Female Wistar rats (n=24) were divided into three experimental groups: "control rats" (n=3) consisting of non-immunized animals, "IRBP-immunized rats" (n=12) and "IPMe-immunized rats" (n=9), which received a subcutaneous injection, respectively, of 13 µg IRBP and 100 µg IPMe emulsified in complete Freund's adjuvant. On days 7, 14 and 21 post immunization, the rats were sacrificed. Nitrites were assessed in plasma and in homogenate of eyes using the Griess reaction. Meanwhile, eyes were collected for histological studies. RESULTS: Our results show the sensitivity of the Wistar strain to both IPMe and IRBP-induced EAU. In fact, we observed histological disorders affecting the retinal tissue in both models of EAU. On the other hand, a significantly increased production of NO in plasma and homogenate of eyes was also observed in comparison to the control group. Moreover, we noted with interest that maximal production of NO occurs prior to the alteration of retinal tissue. CONCLUSION: In summary, our results suggest the early involvement of NO in the mechanisms of pathogenesis of EAU. NO can be considered as a key bio-marker of poor prognosis in ocular autoimmune inflammation.

Sesquiterpenoids and diarylheptanoids from Nidus vespae and their inhibitory effects on nitric oxide production.

Two coriamyrtin-type sesquiterpenes, fengfangin A (1) and tutin (2), and six diarylheptanoids, namely alnusone (3), centrolobol (4), muricarpone B (5), 1-(3,4-dihydroxyphenyl)-7-(4-hydroxyphenyl)heptan-3-one (6), (3S)-1-(3,4-dihydroxyphenyl)-7-(4-hydroxyphenyl)heptan-3-ol (7), and (3S)-1-(4-hydroxyphenyl)-7-(3,4-dihydroxyphenyl)heptan-3-ol (8), were isolated from the 95% EtOH extract of nidus vespae, the nest of Polistes species. Their structures were identified by spectroscopic methods. Compounds 1 and 8 are new products. The absolute configuration of 1 was determined by single-crystal X-ray diffraction analysis using Flack parameter. The biological tests showed that compounds 5, 6, and 8 could inhibit nitric oxide (NO) production in lipopolysaccharide (LPS)-stimulated RAW 264.7 cells with IC(50) values in the range of 13-17 µM, whereas the sesquiterpenes were inactive in this assay (>25 µM). In addition, the ecological significance of the presence of neurotoxic sesquiterpene lactones in nidus vespae is briefly discussed.

Boldo prevents UV light and nitric oxide-mediated plasmid DNA damage and reduces the expression of Hsp70 protein in melanoma cancer cells.

OBJECTIVES: This study was designed to investigate the potential protective effect of a methanolic extract of Peumus boldus leaves on UV light and nitric oxide (NO)-mediated DNA damage. In addition, we investigated the growth inhibitory activity of this natural product against human melanoma cells (M14). METHODS: Boldine, catechin, quercetin and rutin were identified using a HPLC method. The extract was incubated with plasmid DNA and, before irradiating the samples with UV-R, H(2) O(2) was added. For analysis of DNA single-strand breaks induced by NO, the experiments were performed by incubating the extract with Angeli's salt. In the study on M14 cell line, cell viability was measured using MTT assay. Release of lactate dehydrogenase, a marker of membrane breakdown, was also measured. For the detection of apoptosis, the evaluation of DNA fragmentation (COMET assay) and caspase-3 activity assay were employed. The expression of heat shock protein 70 (Hsp70) was detected by Western blot analysis. Generation of reactive oxygen species was measured by using a fluorescent probe. KEY FINDINGS: The extract (demonstrating the synergistic effect of the constituents boldine and flavonoids), showed a protective effect on plasmid DNA and selectively inhibited the growth of melanoma cells. But a novel finding was that apoptosis evoked by this natural product in M14 cells, appears to be mediated, at least in part, via the inhibition of Hsp70 expression, which may be correlated with a modulation of redox-sensitive mechanisms. CONCLUSIONS: These results confirm the promising biological properties of Peumus boldus and encourage in-vivo investigations into its potential anti-cancer activity.

[Effects of pomegranate tannins on experimental gastric damages].

OBJECTIVE: To observe the antiulcer effects of pomegranate tannins in animal models. METHOD: Gastric ulcer models were established by pylorus ligation, intragastric absolute ethanol, and water-immersion stress, respectively. The ulcer index, the contents of nitric oxide (NO) and malondialdehyde (MDA), the activities of glutathione peroxidase (GSH-PX) and superoxide dismutase (SOD) from gastric mucosa of rats, the gastric juice volume, free acidity, total acidity,total acid output, the pepsin activity, the amount of adherent mucus and free mucus were measured, respectively. RESULT: Pomegranate tannins (500, 150, 50 mg x kg(-1)) significantly inhibited ulcerative formation induced by both water immersion stress and pylorus ligation, obviously decreased the gastric mucosa damages induced by intragastric absolute ethanol, in dose-dependent manner. Pomegranate tannins significantly inhibited absolute alcohol-induced elevation of MDA as well as decreasing of NO level, and activities of both SOD and GHS-PX from gastric mucosa. Pomegranate tannins significantly increased the secretion of adherent mucus and free mucus, but did not affect elevation of the free acidity, total acidity, and total acid output, gastric juice volume, gastric pepsin activity induced by pylorus ligation. CONCLUSION: Pomegranate tannins play a protective role against gastric ulcer. Its antiulcer effect is related to increasing secretion of adherent mucus and free mucus from the stomach wall, which may inhibit generation of oxygen-derived free radicals, and decrease the consumption of GSH-PX and SOD, and maintain content of NO at normal level.

An in vitro examination of the antioxidant and anti-inflammatory properties of buckwheat honey.

OBJECTIVE: Hydroxyl radical and hypochlorite anion formed at the wound site from superoxide anion produced by activated polymorphonuclear neutrophils (PMNs) are considered important factors in impaired wound healing. Superoxide anion may also react with nitric oxide produced by macrophages to form peroxynitrite, a third strong oxidant that damages surrounding tissue. In order to select honey for use in wound-healing products, different samples were compared for their capacity to reduce levels of reactive oxygen species (ROS) in vitro. METHOD: Honey samples were tested in assays for inhibition of ROS production by activated human PMNs, antioxidant activity (scavenging of superoxide anion in a cell-free system) and inhibition of human complement (reducing levels of ROS by limiting formation of complement factors that attract and stimulate PMNs). For buckwheat honey (NewYork, US), moisture and free acid content were determined by refractive index measurement and potentiometric titration respectively. Honey constituents other than sugars were investigated by thin layer chromatography, using natural product reagent to detect phenolic compounds. Constituents with antioxidant properties were detected by spraying the chromatogram with DPPH. RESULTS: Although most honey samples were shown to be active, significant differences were observed, with the highly active honey exceeding the activities of samples with minor effects by factors of 4 to 30. Most pronounced activities were found for American buckwheat honey from the state of NewYork. Phenolic constituents of buckwheat honey were shown to have antioxidant activity. CONCLUSION: As buckwheat honey was most effective in reducing ROS levels, it was selected for use in wound-healing products. The major antioxidant properties in buckwheat honey derive from its phenolic constituents, which are present in relatively large amounts. Its phenolic compounds may also exert antibacterial activity, whereas its low pH and high free acid content may assist wound healing.

Nitronaproxen: AZD 3582, HCT 3012, Naproxen Nitroxybutylester, NO-Naproxen.

Nitronaproxen [AZD 3582, HCT 3012, naproxen nitroxybutylester, NO-naproxen] is a naproxen derivative with similar anti-inflammatory activity to the parent compound, but with less gastrointestinal toxicity. It is the first of a new class of analgesic and anti-inflammatory drugs known as cyclo-oxygenase-inhibiting nitric oxide donators (CINODs), which are under development by NicOx. The better gastrointestinal tolerability of nitronaproxen appears to be due to its release of nitric oxide (NO) and the consequent maintenance of tissue perfusion and integrity. Nitronaproxen is in phase III clinical development for the treatment of osteoarthritis and is available for licensing. AstraZeneca had been a worldwide licensee for nitronaproxen and other CINODs. However, the results of phase II clinical trials of nitronaproxen did not fulfill AstraZeneca's strategic commercial criteria for further investment and NicOx reacquired rights following AstraZeneca's decision to discontinue its involvement in 2003. NicOx was surprised by AstraZeneca's decision, and remained fully convinced of the potential of nitronaproxen. NicOx is seeking new partners for development of compounds of the CINOD class. Nitronaproxen is in a phase III clinical trial for the treatment of osteoarthritis (OA) of the knee. The 13-week trial completed enrolment of 820 patients from 120 clinical sites in the US in May 2006. The study is designed to confirm that nitronaproxen is superior to placebo and is as effective as naproxen in relieving signs and symptoms of OA. The study will also seek to show that nitronaproxen has no adverse effect on blood pressure. An additional trial has begun that is employing ambulatory blood pressure monitoring to provide a description of the blood pressure effect of nitronaproxen over a 24-hour period in hypertensive subjects. This US trial will enrol approximately 120 volunteers with stable essential hypertension. The volunteers will not have osteoarthritis but will be between the ages of 50 and 75 years (representative of the osteoarthritis population). Results from both trials are expected in the fourth quarter of 2006. The phase II clinical programme for nitronaproxen, which included 2709 patients in five separate clinical studies, showed that the drug is a potent, safe anti-inflammatory agent, with potential for improved cardiovascular safety over NSAIDs and COX-2 selective NSAIDs. An independent advisory board recommended further development of nitronaproxen in the treatment of osteoarthritis in 2004 based on an evaluation of the full results of the phase II clinical programme.A clinical study had begun in September 2004 at the University of Pennsylvania in patients with mild essential hypertension, in which the effects of nitronaproxen and rofecoxib on arterial blood pressure would be compared. However, rofecoxib was withdrawn worldwide on 1 October 2004. It is unclear if the trial was completed. The STAR Multinational Study Group has conducted a phase II gastrointestinal safety and efficacy study of nitronaproxen versus naproxen in 970 patients with osteoarthritis at 80 sites in the following countries: Argentina, Brazil, Hungary, Mexico, Norway, Poland, South Africa and the UK. The study was completed in November 2002. AstraZeneca conducted a randomised, phase II trial evaluating the efficacy and safety of nitronaproxen among 672 subjects with symptomatic knee osteoarthritis. Results have been presented. Certain phase II trial data from 2003 had been somewhat disappointing. However, an underpowered trial and failures and deficiencies in a trial meant that it was not possible to draw conclusions from this data.

Brief exposures to NO2 augment the allergic inflammation in asthmatics.

Exposure to high ambient levels of nitrogen dioxide (NO2) enhances the airway reaction in humans to allergen, measured as decreased pulmonary function. We tested whether this NO2 effect is associated with an increased inflammatory response to allergen in the airways. To mimic real-life conditions, in which exposure to high ambient levels of NO2 occurs only during short periods of time but often several times a day, we used a repeated-exposure model. On day 1, 18 subjects with allergic asthma were exposed, in randomized order, to purified air or to 500 microg/m3 NO2 for 15 min, and on day 2 for 2 x 15 min. Allergen was inhaled 3-4h after the NO2 exposures on both days. Symptoms, pulmonary function, and inflammatory response in sputum and blood were measured daily. Eosinophil cationic protein in both sputum and blood increased more from day 1 to day 3 after NO2+allergen than after air+allergen, whereas eosinophil counts did not differ. The change in myeloperoxidase was significantly greater after NO2+allergen than after air+allergen in blood but not in sputum. This finding was not accompanied by raised levels of neutrophils in sputum and blood. Symptoms and pulmonary function were equally affected by NO2+allergen and air+allergen. We conclude that two to three brief exposures to ambient levels of NO2 can prime circulating eosinophils and enhance the eosinophilic activity in sputum in response to inhaled allergen. This might be an important mechanism by which air pollutants amplify the inflammatory reactions in the airways.

Is Gulf War Syndrome really a mystery?

Since the end of the 1991 Gulf War about 20,000 United States veterans and similar proportions of troops from other allied contingents have been affected by a variety of symptoms which have collectively become known as 'Gulf War Syndrome'. Similar symptoms have been reported in Iraqi civilians including children. Despite extensive investigations no agreement has been reached on whether there is an underlying cause or causes. In this article, the principal features of the illness are summarised and some of the proposed causes discussed. It is proposed that the common cause is the toxic smoke from incomplete combustion of oil from burning wells, and this hypothesis is related to the known toxicology of two likely combustion products, nitric oxide and carbon monoxide. The effect of this proposal on possible investigations and treatment is considered.

Teratological consequences of nitric oxide synthesis inhibition.

Nitric oxide (NO) is generated by a family of NO synthase (NOS) enzymes, including endothelial (eNOS), inducible (iNOS) and neuronal (nNOS). NO is an important bioregulator of a wide variety of physiological processes. Recent experimental evidence indicates that inhibition of NO synthesis can lead to teratogenesis. The current review focuses on this aspect of NOS. Exposure of pregnant rodents to non-selective NOS inhibitors, such as N(G)-nitro-L-arginine-methyl ester (L-NAME) and N(G)-nitro-L-arginine (L-NNA), has been linked to limb reduction defects. The teratogenic phenotype, characterized by hemorrhage and transverse terminal tissue destruction, has been regarded to be compatible with a vascular origin. The critical time for teratogenic response was traced to advanced stages of gestation. Similar limb reduction defects have been described in mice deficient in eNOS, but not in other NOS isoforms. Several observations have led to the proposal that hypoxia and possible consequential generation of reactive oxygen species are involved in the causation of NOS inhibitors induced limb defects.

Differential effect of phosphodiesterase IV inhibitor RP73401 on various inflammatory and immune responses relevent to rheumatoid arthritis.

Phosphodiesterase (PDE) IV inhibitors have been reported to possess potent anti-inflammatory activities through enhancement of cAMP. In this study, the immunopharmacological effect of PDE IV inhibitor (RP73401) was further carefully evaluated. RP73401 strongly blocked the production of tumor necrosis factor (TNF)-alpha from lipopolysaccharide (LPS)-stimulated murine macrophages (RAW264.7) and human peripheral blood mononuclear cells (PBMC) and LPS-primed mice. RP73401 did not relieve joint inflammation in adjuvant-arthritis (RA) model, whereas the compound attenuated arachidonic acid-induced inflammation. RP73401 displayed weak or no modulatory effects on the activation of macrophage and lymphocytes (assessed by proliferation, nitric oxide (NO) release and cell-cell adhesion, TNF-alpha production upon phorbol 12-myristate 13-acetate (PMA) treatment), and fluorescein-isothiocynate (FITC)-induced ear oedema. Collectively, these data suggest that PDE IV inhibitor RP73401 may differentially modulate various immune responses and these may explain its inability to inhibit adjuvant-induced joint inflammation or FITC-induced ear oedema.

Reactive nitrogen species scavenging, rather than nitric oxide inhibition, protects from articular cartilage damage in rat zymosan-induced arthritis.

1. The contribution of nitric oxide (NO) and peroxynitrite (PN) to inflammation in a zymosan-induced (1 mg, intra-articular, i.art.) rat model of arthritis was assessed by histopathology and by measuring the glycosaminoglycan (GAG) content of the articular cartilage. 2. Progression of the chronic synovitis in zymosan-induced arthritis (ZYA) was associated with increased nitrite and nitrotyrosine (3-NT) levels in the joint exudates that paralleled a progressive loss of the GAG content. An increase in 3-NT was also observed after i.art. PN. 3. The nonselective nitric oxide synthase (NOS) inhibitor l-N(G)-nitroarginine methyl ester (25-75 mg x kg(-1)day(-1)) or the selective inducible NOS inhibitor aminoguanidine (50-100 mg x kg(-1)day(-1)) given 1 h before (prophylactic) or 3 days after (therapeutic) injection of the zymosan ameliorated the synovitis, but worsened the GAG loss, as measured at the end of the experiment (day 7). 4. The PN scavenger uric acid (100-250 mg x kg(-1) i.p. four times daily) given prophylactically until the end of the experiment (day 14), in a dose compatible with its PN scavenging activity, significantly decreased both the synovitis and the GAG loss. 5. In conclusion, PN formation is associated with cartilage damage in addition to proinflammatory activity in ZYA. NOS inhibitors and a PN scavenger were able to reduce the cellular infiltration, while displaying opposite effects on cartilage homeostasis either by enhancing or ameliorating the damage, respectively.