[Effect of dinitrosyl iron complex with glutathione as a nitric oxide donor on blood circulation in healthy animals]

It has been shown that the hypotensive action of the nitric oxide donor, the dinitrosyl complex of iron with glutathione, on the organism of healthy rats, which is caused by a decrease in the general peripherical immunity, does not impair the microcirculation and is accompanied by an enhancement of the contractile activity of the myocardium. In hypotension caused by the dinitrosyl iron complex, neither the tension of oxygen and nitrogen in the blood nor its basic-acidic status changes. Thus, the possible inhibitory action of this complex on some enzymes and proteins in the animal organism does not affect the functioning of the heart, vessels, and blood. The dinitrosyl iron complex with glutathione only causes a decrease in arterial pressure. It is assumed that these complexes as well as dinitrosyl complexes of iron with other thiol ligands may be considered as the basis for designing a novel type of drugs for the treatment of cardiovascular diseases.

Nitric oxide (NO)-releasing aspirin and (NO) donors in protection of gastric mucosa against stress

Acute gastric mucosal lesions represent an important clinical problem. The experimental model of acute gastritis such as water immersion restraint (WRS) stress is useful tool in examination of pathomechanism of acute gastric damage. Nitric oxide (NO) plays an important role in the maintenance of gastric barrier, however the role of reactive oxygen species (ROS) in the interaction between NO and gastric mucosa integrity has been little studied. The purpose of our present study was to explain the participation of ROS in healing of WRS-induced gastric lesions accelerated by NO. Experiments were carrying out on 120 male Wistar rats. To assess gastric blood flow (GBF) laser Doppler flowmeter was used. The number of gastric lesions was established by planimetry. The colorimetric assays were used to determine gastric tissue level of malondialdehyde (MDA) and 4-hydroxynonenal (4-HNE), the products of lipid peroxidation by ROS, as well as superoxide dismutase (SOD) activity, the enzyme scavanger of ROS. We demonstrated that 3.5 h of WRS resulted in appearance of acute gastric mucosal lesions accompanied by a significant decrease of GBF. Biological effects of ROS were estimated by measuring tissue level of MDA and 4-HNE, as well as the SOD activity. It was demonstrated that 3.5 h of WRS led to significant increase of MDA and 4-HNE mucosal level, that was accompanied by a decrease of SOD activity. Pretreatment with NO-donors (SIN-1, SNAP, nitroglycerin, NO-ASA) resulted in reduction of gastric lesions number, increment of GBF, decrease of MDA and 4-HNE tissue level and increase of SOD activity. Suppression of ROS play an important role in NO-donors action in gastroprotection against gastric acute lesions induced by 3.5 h of WRS. NO-donors cause an attenuation of lipid peroxidation as documented by a decrease of MDA and 4-HNE levels and enhancement of antioxidative properties as evidenced by increase of SOD activity.

[Exogenous nitric oxide donor in the liver inflammatory and hemodynamic response after hemorrhagic shock]

BACKGROUND

Hemorrhagic shock (HS) results in oxidative stress to cells and in the induction of the inflammatory response, with an increased expression of a number of proinflammatory mediators and cytokines. We tested the ability of the nitric oxide (NO) donor sodium nitroprusside (NP) to reduce tissue injury in a rodent model of uncontrolled hemorrhagic shock.

METHODS

Seventy two Sprague Dawley rats weighing 250-300 g were subjected to a model of uncontrolled hemorrhagic shock. Four groups of animals were included (n = 18 per group): sham/saline, sham/NP, shock/saline, shock/NP. Experimental design consisted of the development of hemorrhagic shock (3 ml/100 g) in a 15-min period, tail amputation (75%) and drug administration at 30 min, fluid resuscitation (FR) with Ringer's lactate (RL) solution to reach a mean arterial pressure (MAP) of 40 mmHg, a hospital phase of 60 min with hemostasis and FR with LR solution to reach a MAP of 70 mmHg, and a 3-day observation phase. Treatment at the beginning of resuscitation included either normal saline (groups 1, 3) or NP (0.5 mg/kg) (groups 2, 4). The following parameters were evaluated: fluid requirements for resuscitation, liver injury tests, liver tissue myeloperoxidase (MPO), liver histology, and 3-day survival.

RESULTS

NP significantly reduced fluid requirements for resuscitation (p = 0.0001). We also observed an improved statistically significant difference in tests demonstrating hepatic injury (p = 0.0001), neutrophil infiltration as evidences by liver MPO (p <0.05), and histology studies (p = 0.001). Survival was also increased from 40% in controls to 60% with NP treatment.

CONCLUSIONS

These data suggest that excess NO mediates hemorrhage-induced liver injury, and that the suppression of NO with NP may reduce the pathological consequences of severe hemorrhage, possibly by scavenging superoxide (O(2)(-)), thus limiting the production of more aggressive radicals.

Nitric oxide and cardiovascular and renal effects

Nitric oxide (NO) has multiple protective effects for regulating the cardiovascular and renal systems. The major functions include endothelium-dependent relaxation, anti-inflammatory effects, as well as antihypertrophic and antithrombotic activities. Many of the activities mediated by NO are systematically antagonized by angiotensin-II (Ang II), a vasconstrictor peptide. Studies described in the review below have demonstrated that the balance between NO and Ang II activities rather than the absolute concentration of each molecule determines their effects on the physiology and pathophysiology of the cardiovascular and renal systems. NO donors have been used for years as therapeutic agents for a range of cardiovascular conditions including angina, myocardial infarction and for the reduction of arterial stiffness. An understanding of the mechanisms underlying the effects of these medications will enable the development of novel therapies to balance the effects of NO in the cardiovascular system.

[Therapeutic effect of recombinant human brain natriuretic peptide for treatment of decompensated heart failure: comparison with nitroglycerin]

OBJECTIVE

To compare the therapeutic effect of recombinant human brain natriuretic peptide (rhBNP) and nitroglycerin on acute decompensated heart failure (ADHF).

METHODS

Fifty ADHF patients were randomly divided into rhBNP group and nitroglycerin group. In all the patients, dyspnea and global clinical status were assessed before and at 30 min, 6 h and 24 h after drug administration, and the volume of fluid intake and urine along with hemodynamic parameters was recorded 24 h after drug administration. In the nitroglycerin group, the patients received an initial nitroglycerin dose of 5 microg/min, with subsequent dose increment of 5 microg/min every 3 to 5 min; the dose was adjusted individually according to the hemodynamics of the patients. The patients in rhBNP group were given rhBNP at the initial dose of 1.5 microg/kg by with an intravenous bolus injection followed by infusion at the rate of 0.0075 microg.kg(-1).min(-1) for 72 h.

RESULTS

At 30 min and 6 h after drug administration, the patients in the rhBNP group showed significant greater improvement of dyspnea (P=0.042 and 0.019) and global clinical status (P=0.018 and 0.044) than those in the nitroglycerin group, but 24 h after drug administration, no significant difference was noted between the two groups (P=0.192 and 0.179). Twenty-four hours after drug administration, the mean urine volume was significantly greater in rhBNP group than in nitroglycerin group (1513.8-/+242.9 vs 1341.2-/+239.7 ml, P=0.015), and the ejection fraction increased and pulmonary arterial pressure and systolic blood pressure decreased at greater amplitude in the former group (P=0.001,0.000 and 0.002, respectively). At 72 h, the numbers of premature ventricular contraction and couplets premature beats and onset of paroxysmal ventricular tachycardia were significantly reduced in rhBNP group as compared with the nitroglycerin group (P=0, 0.001 and 0.002, respectively).

CONCLUSION

RhBNP promotes urine excretion, decreases pulmonary arterial pressure and increases left ventricular ejection fraction to improve dyspnea and global clinical status and reduce the onset of ventricular arrhythmia in ADHF patients.

Nitrates and NO-NSAIDs in cancer chemoprevention and therapy: in vitro evidence querying the NO donor functionality

Properties of the NO-ASA family of NO-donating NSAIDs (NO-NSAIDs), notably NCX 4016 (mNO-ASA) and NCX 4040 (pNO-ASA), reported in more than one hundred publications, have included positive preclinical data in cancer chemoprevention and therapy. Evidence is presented that the antiproliferative, the chemopreventive (antioxidant/electrophile response element (ARE) activation), and the anti-inflammatory activity of NO-ASA in cell cultures is replicated by X-ASA derivatives that are incapable of acting as NO donors. pBr-ASA and mBr-ASA are conisogenic with NO-ASA, but are not NO donors. The biological activity of pNO-ASA is replicated by pBr-ASA; and both pNO-ASA and pBr-ASA are bioactivated to the same quinone methide electrophile. The biological activity of mNO-ASA is replicated by mBr-ASA; mNO-ASA and mBr-ASA are bioactivated to different benzyl electrophiles. The observed activity is likely initiated by trapping of thiol biomolecules by the quinone and benzyl electrophiles, leading to depletion of GSH and modification of Cys-containing sensor proteins. Whereas all NO-NSAIDs containing the same structural "linker" as NCX 4040 and NCX 4016 are anticipated to possess activity resulting from bioactivation to electrophilic metabolites, this expectation does not extend to other linker structures. Nitrates require metabolic bioactivation to liberate NO bioactivity, which is often poorly replicated in vitro, and NO bioactivity provided by NO-NSAIDs in vivo provides proven therapeutic benefits in mitigation of NSAID gastrotoxicity. The in vivo properties of X-ASA drugs await discovery.

Is NO the king? Pathophysiological benefit with uncertain clinical impact

NO is the "hero" molecule of the last few decades. It is a ubiquitous and omnipotent radical with both hemodynamic and antiproliferative effects within the cardiovascular system. NO is an important counterregulatory factor for vasoconstrictors and growth promoting substances. Endothelial dysfunction with decreased NO production is related to many cardiovascular disorders, such as coronary artery disease, heart failure and hypertension. Despite the important role of NO within the circulation, there is only limited evidence in the form of large clinical trials that NO delivery can reduce cardiovascular morbidity and mortality. Thus, NO donors are not in the first line therapy in ischemic heart disease, heart failure or arterial hypertension and NO delivery is recommended only in particular clinical situations, when a well established treatment is contraindicated or has an insufficient effect. It is concluded that the insufficient NO production is the principal disorder in endothelial dysfunction, which is related to cardiovascular pathology with deteriorated prognosis, but the impact of therapeutically increased NO bioactivity on the morbidity and mortality is inferior to well established treatment with ACE-inhibitors, AT(1) receptor blockers, beta-blockers, statins and certain antihypertensive drugs. There is little doubt that NO is king in the circulation, but kings seldom decide the battles.

[Effect of exogenous donors of nitric oxide and inhibitors of its enzymatic synthesis on experimental ischemic thrombosis in conjunctive veins of the rabbit eyes]

The beneficial action of dinitrosyl iron complex with glutathione on conjunctive veins of eyes in rabbits with experimental thrombosis of conjunctive veins has been demonstrated. Aqueous solutions of dinitrosyl iron complexes were added subconjunctively at doses of 5.4-8.1 micromole per eye. The average duration of thrombosis by the action of dinitrosyl iron complex decreased from 6.4 days in control animals to 2 days. The addition of dinitrosyl iron complex resulted in blood flow recovery in occlusive vessels and prevented ischemia and necrosis of tissues. The enhancement of hemorrhagic activity induced by dinitrosyl iron complexes was abrogated with combined addition of the nonselective NO synthase inhibitor N-nitro-L-arginine. In contrast, S-nitrosoglutathione affected adversely the veins: the duration of thrombosis in experimental thrombosis of conjunctive veins increased to 7 days. Intensive hemorhage developed in the conjunctive. The formation of protein-bound dinitrosyl iron complexes was observed by the EPR method in eye tissues after the subconjunctive or parabulbar addition of dinitrosyl iron complex with glutathione. This was not the case when the complex was injected intravenously. It was shown that dinitrosyl iron complex with glutathione induces the blockade of pellet aggregation or strengthens the fibrinolytic activity of plasma of patients with eye vessel pathology. The beneficial action of dinitrosyl iron complexes on conjunctive veins was proposed to be due to the capacity of dinitrosyl iron complexes to donate NO primarily to its biological targets. The release of free NO molecules in large amounts is not characteristic for dinitrosyl iron complexes. This process is characteristic of S-nitrosoglutathione, which sharply increases the probability of the accumulation of peroxynitrite, which produces a toxic effect on cells and tissues.

Efficacy of Nitric Oxide in Stroke - a randomized trial. Characteristics of patients recruited in Poland

BACKGROUND AND PURPOSE

High blood pressure is frequent in patients with acute stroke. It frequently returns back to normal values within the first days after onset. It is not yet established whether it requires treatment or not. The Efficacy of Nitric Oxide in Stroke (ENOS) trial aims to assess the efficacy of transdermal glyceryl trinitrate (GTN) patches versus control and stopping or continuing antihypertensive treatments in stroke. The rationale for the study is presented and characteristics of patients recruited in Poland and elsewhere compared.

MATERIAL AND METHODS

Patients were recruited to the ENOS study by 1 November, 2007. Baseline characteristics and outcome at 90 days were compared.

RESULTS

Of 783 patients overall, 78 patients were recruited in Poland. The age of the patients was similar in the two groups (70.0 vs. 69.1 years). There were fewer males among Polish patients (46.8% vs. 58.3%) and fewer intracranial haemorrhages (3.8% vs. 16.7%). There were more patients with no lesions on CT (41.8% vs. 19.3%). Polish patients more frequently had hypertension (76.0% vs. 66.4%) and subsequently more frequently had antihypertensive treatment (60.8% vs. 45.3%) and nitrates (10.1% vs. 5.0%). The number of patients independent after 3 months was similar.

CONCLUSIONS

Polish patients are slightly different from those treated in other countries, but at the moment the patient groups are too small to fully compare patient characteristics in different countries. The trial is ongoing and more centres are welcome to join.

Drugs for the perioperative control of hypertension: current issues and future directions

The management of hypertension continues to pose important challenges. Recent developments have established the importance of more rigorous blood pressure control in the community. In the perioperative setting, hypertension has long been recognised as undesirable, although the adverse impact of high blood pressure on the acute risks of elective surgery may have been previously overstated.A number of agents and techniques are available to control blood pressure perioperatively. These include principally general and regional anaesthetics, alpha(2)-adrenoceptor agonists, peripheral alpha(1)- and beta-adrenoceptor antagonists, dihydropyridine calcium channel antagonists, dopamine D(1A)-receptor agonists (fenoldopam), and nitric oxide donors. Recent years have seen important developments in the receptor selectivity of new compounds and in pharmacokinetics, particularly esterase metabolism. The future study of genomics may enable us to identify patients at risk for hypertension-related adverse events and target therapies most effectively to these high-risk groups.

Maternal and fetal hemodynamic effects induced by nitric oxide donors and plasma volume expansion in pregnancies with gestational hypertension complicated by intrauterine growth restriction with absent end-diastolic flow in the umbilical artery

OBJECTIVE

To evaluate the effect of plasma volume expansion (PVE) and nitric oxide (NO) donors, in addition to antihypertensive therapy for gestational hypertensive pregnancies complicated by intrauterine growth restriction (IUGR) with absent end-diastolic flow (AEDF) in the umbilical artery (UA).

METHODS

This was a case-control study into which 32 gestational hypertensive pregnancies with IUGR and AEDF were enrolled. Sixteen of these were treated with antihypertensive drugs, NO donors and PVE (Group A), and 16, matched for maternal age, gestational age and fetal conditions, were treated with antihypertensive drugs only (Group B). All patients underwent fetal and uteroplacental assessment and maternal echocardiography to evaluate total vascular resistance (TVR) and cardiac output before and 5-14 days after initiation of treatment.

RESULTS

After 5-14 days of treatment, the maternal TVR in Group A fell from 2170 +/- 248 to 1377 +/- 110 dynes.s.cm(-5) (P < 0.01), and that in Group B fell from 2090 +/- 260 to 1824 +/- 126 dynes.s.cm(-5) (P < 0.01), with the reduction being greater in Group A than in Group B (P < 0.01). There was a significant increase in cardiac output in Group A after 5-14 days of treatment vs. baseline (6.19 +/- 0.77 vs. 4.32 +/- 0.66, P < 0.001), and, after treatment, cardiac output was significantly greater in Group A than it was in Group B (6.19 +/- 0.77 vs. 4.70 +/- 0.44, P < 0.001). Reappearance of end-diastolic flow in the UA occurred in 14/16 patients in Group A but in no patients in Group B (87.5% vs. 0%, P < 0.05). The interval between detection of UA-AEDF and delivery was 28 +/- 16 days in Group A and 11 +/- 6 days in Group B (P < 0.05).

CONCLUSION

Administration of NO donors and PVE in gestational hypertensive pregnancies affected by IUGR and UA-AEDF appears to improve both maternal and fetal hemodynamics, inducing prolongation of gestation.

Possible new antiaging strategies related to neuroendocrine-immune interactions

The aging process demonstrates gradual and spontaneous changes, resulting in maturation through childhood, puberty and young adulthood, and then decline through middle and late age. However, animals and humans are capable of reaching the extreme limit of life span characteristic for the species with a very efficient network of antiaging mechanisms. Among them, neuroendocrine-immune interactions play a pivotal role. The loss of the capacity of the organism in remodeling the neuroendocrine-immune response leads to the appearance of age-associated pathologies. We herein report some substances which can be proposed as new antiaging strategies because of their capacity to remodel some biological functions in old animals and humans. These substances are: L-deprenyl, leptin, ghrelin, carnosine and NO donors. Their role as possible antiaging strategies in healthy people in relation to neuroendocrine-immune responses and zinc ion bioavailability is reported and discussed.

[Endothelium and nitric oxide]

Studied nature of the "blood vessels relaxing factor" derived from endothelium that was identified as nitric oxide caused intensive scientific research on nitric oxide regarding some aspects of its impact on human physiological and pathological processes. The objective of this short review is to discuss widely used (in the clinical practice) direct and indirect donors of nitric oxide and/or other agents, increasing nitric oxide concentration in human body, and their beneficial role for the prevention of atherosclerosis. Under physiological conditions, endothelium regulates the tone of blood vessels, homeostasis of which is maintained by endothelium-generated vasoconstrictors and vasodilators. The most important vasodilator and the main substance produced by the endothelium is nitric oxide. The failure of synthesis and/or the lost of nitric oxide bioavailability is the major feature of endothelial dysfunction and key factor initiating progression of atherosclerosis. The endothelial dysfunction initiates the series of events, which stimulate and aggravate the course of atherosclerosis by increasing endothelial permeability, platelet aggregation, and leukocyte adhesion, and cytokine expression. Further, the review deals with the mechanisms of action of statins, angiotensin-converting enzyme inhibitors, L-arginine, direct nitric oxide donors (nitroglycerin, isosorbide mononitrate and isosorbide dinitrate), and indirect nitric oxide donors (phosphodiesterase-V inhibitors, K(ATP) openers).

Nitric oxide and nanotechnology: a novel approach to inhibit neointimal hyperplasia

OBJECTIVE

Nitric oxide (NO) has been shown to inhibit neointimal hyperplasia after arterial interventions in several animal models. To date, however, NO-based therapies have not been used in the clinical arena. Our objective was to combine nanofiber delivery vehicles with NO chemistry to create a novel, more potent NO-releasing therapy that can be used clinically. Thus, the aim of this study was to evaluate the perivascular application of spontaneously self-assembling NO-releasing nanofiber gels. Our hypothesis was that this application would prevent neointimal hyperplasia.

METHODS

Gels consisted of a peptide amphiphile, heparin, and a diazeniumdiolate NO donor (1-[N-(3-Aminopropyl)-N-(3-ammoniopropyl)]diazen-1-ium-1,2-diolate [DPTA/NO] or disodium 1-[(2-Carboxylato)pyrrolidin-1-yl]diazen-1-ium-1,2-diolate [PROLI/NO]). Nitric oxide release from the gels was evaluated by the Griess reaction, and scanning electron microscopy confirmed nanofiber formation. Vascular smooth muscle cell (VSMC) proliferation and cell death were assessed in vitro by (3)H-thymidine incorporation and Personal Cell Analysis (PCA) system (Guava Technologies, Hayward, Calif). For the in vivo work, gels were modified by reducing the free-water content. Neointimal hyperplasia after periadventitial gel application was evaluated using the rat carotid artery injury model at 14 days (n = 6 per group). Inflammation and proliferation were examined in vivo with immunofluorescent staining against CD45, ED1, and Ki67 at 3 days (n = 2 per group), and graded by blinded observers. Endothelialization was assessed by Evans blue injection at 7 days (n = 3 per group).

RESULTS

Both DPTA/NO and PROLI/NO, combined with the peptide amphiphile and heparin, formed nanofiber gels and released NO for 4 days. In vitro, DPTA/NO inhibited VSMC proliferation and induced cell death to a greater extent than PROLI/NO. However, the DPTA/NO nanofiber gel only reduced neointimal hyperplasia by 45% (intima/media [I/M] area ratio, 0.45 +/- 0.07), whereas the PROLI/NO nanofiber gel reduced neointimal hyperplasia by 77% (I/M area ratio, 0.19 +/- 0.03, P < .05) vs control (injury alone I/M area ratio, 0.83 +/- 0.07; P < .05). Both DPTA/NO and PROLI/NO nanofiber gels significantly inhibited proliferation in vivo (1.06 +/- 0.30 and 0.19 +/- 0.11 vs injury alone, 2.02 +/- 0.20, P < .05), yet had minimal effect on apoptosis. Only the PROLI/NO nanofiber gel inhibited inflammation (monocytes and leukocytes). Both NO-releasing nanofiber gels stimulated re-endothelialization.

CONCLUSIONS

Perivascular application of NO-releasing self-assembling nanofiber gels is an effective and simple therapy to prevent neointimal hyperplasia after arterial injury. Our study demonstrates that the PROLI/NO nanofiber gel most effectively prevented neointimal hyperplasia and resulted in less inflammation than the DPTA/NO nanofiber gel. This therapy has great clinical potential to prevent neointimal hyperplasia after open vascular interventions in patients.

Dysfunction of nitric oxide synthases as a cause and therapeutic target in delayed cerebral vasospasm after SAH

Nitric oxide (NO), also known as endothelium-derived relaxing factor, is produced by endothelial nitric oxide synthase (eNOS) in the intima and by neuronal nitric oxide synthase (nNOS) in the adventitia of cerebral vessels. It dilates the arteries in response to shear stress, metabolic demands, pterygopalatine ganglion stimulation, and chemoregulation. Subarachnoid haemorrhage (SAH) interrupts this regulation of cerebral blood flow. Hemoglobin, gradually released from erythrocytes in the subarachnoid space destroys nNOS-containing neurons in the conductive arteries. This deprives the arteries of NO, leading to the initiation of delayed vasospasm. But such vessel narrowing increases shear stress, which stimulates eNOS. This mechanism normally would lead to increased production of NO and dilation of arteries. However, a transient eNOS dysfunction evoked by an increase of the endogenous competitive nitric oxide synthase (NOS) inhibitor, asymmetric dimethyl-arginine (ADMA), prevents this vasodilation. eNOS dysfunction has been recently shown to be evoked by increased levels of ADMA in CSF in response to the presence of bilirubin-oxidized fragments (BOXes). A direct cause of the increased ADMA CSF level is most likely decreased ADMA elimination due to the disappearance of ADMA-hydrolyzing enzyme (DDAH II) immunoreactivity in the arteries in spasm. This eNOS dysfunction sustains vasospasm. CSF ADMA levels are closely associated with the degree and time-course of vasospasm; when CSF ADMA levels decrease, vasospasm resolves. Thus, the exogenous delivery of NO, inhibiting the L-arginine-methylating enzyme (IPRMT3) or stimulating DDAH II, may provide new therapeutic modalities to prevent and treat vasospasm. This paper will present results of preclinical studies supporting the NO-based hypothesis of delayed cerebral vasospasm development and its prevention by increased NO availability.

[Cardioprotective efficacy of dinitrosyl iron complex with L-cysteine in rats in vivo]

The effect ofdinitrosyl iron complex (DNIC) with L-cysteine on the hemodynamic indices and the size of myocardial infarction, which was induced by 40-min regional ischemia and subsequent 60-min reperfusion, have been studied in rats in vivo. Intravenous bolus injection of DNIC (3.1 micromol/kg body weight in 0.5 ml saline) was performed before regional ischemia; the control group was administered the same volume of saline. DNIC administration significantly decreased the mean blood pressure throughout the experiment. DNIC reduced the duration of cardiac arrhythmias to 170 +/- 10 s as against 445 +/- 30 s in control. The myocardial infraction size significantly decreased in the DNIC group compared to control (38.0 +/- 1.4 and 48.0 +/- 3.9% of the area at risk, respectively; p < 0.05). A combination of the vasodilatory effect of DNIC with the reduction of the damaging effect of cardiac ischemia and reperfusion encourage the development of hypotensive and antiischemic drugs on this class of NO donors.

NSAIDs, coxibs, CINOD and H2S-releasing NSAIDs: what lies beyond the horizon

Nonsteroidal anti-inflammatory drugs are widely prescribed for treatment of pain and inflammation, despite their association with gastrointestinal complications, including bleeding and perforation. Inhibition of cyclo-oxygenases, is the main mechanism of action of aspirin and nonsteroidal anti-inflammatory drugs. Non-selective nonsteroidal anti-inflammatory drugs inhibit cyclo-oxygenase-1 and cyclo-oxygenase-2. Inhibition of cyclo-oxygenase-1 derived prostanoids in the stomach represent the underlying mechanism involved in development of gastric and duodenal ulcers in patients taking nonsteroidal anti-inflammatory drugs. Selective cyclo-oxygenases-2 inhibitor (coxibs) spare cyclo-oxygenase-1 show enhanced safety profile in the gastrointestinal tract, but increase the risk of heart attack and stroke. Spurred by these findings, two coxibs, rofecoxib and valdecoxib, were withdrawn from the market. In addition to prostanoids, two gaseous mediators, nitric oxide (NO) and hydrogen sulfide (H(2)S) exert protective effects in gastric mucosa. The inhibitory effects of NO on nonsteroidal anti-inflammatory drugs-induced leukocyte adherence have been exploited in the development of NO-releasing nonsteroidal anti-inflammatory drugs, also indicated as cyclo-oxygenase-inhibiting NO-donating drugs. Despite its non-selective profile versus cyclo-oxygenase isoenzymes, naprocyclo-oxygenase-inhibiting NO-donating drugs, the prototype of this class of anti-inflammatory agents, reduces systemic blood pressure and might have enhanced cardiovascular safety than coxibs, while causing less gastrointestinal damage than its parent drug, the naproxen. H(2)S-releasing nonsteroidal anti-inflammatory drugs derivatives have been recently developed, based on the observed ability of this gaseous mediator to cause vasodilation and to prevent leukocyte adherence. In pre-clinical settings, H(2)S-releasing nonsteroidal anti-inflammatory drugs produce less gastric damage as compared to the parent drugs. Cyclo-oxygenases-inhibiting NO-donating drugs and H(2)S-releasing nonsteroidal anti-inflammatory drugs represent examples of new anti-inflammatory drugs created through the exploitation of the beneficial effects of endogenous gaseous mediators in the gastrointestinal and cardiovascular systems.

Mouse models of asthma: can they give us mechanistic insights into the role of nitric oxide?

New clinical practice guidelines for patients with asthma include the recommendation to monitor exhaled breath nitric oxide (NO) levels. NO concentrations in exhaled breath are increased in asthmatics and increased NO levels correlate with worsening airway inflammation and asthma symptoms. The multiple roles of NO in the lung have not been delineated clearly. Clinical trials are being performed presently that test the apparently conflicting hypotheses that either donors or inhibitors of NO in the lung are effective strategies for treating asthma. These strategies evolved, in part, from results of pre-clinical studies performed in mice and other animal models. This review evaluates the existing literature with regard to mouse models of asthma and explores the often conflicting data on the role of NO, the nitric oxide synthase (NOS) enzymes, and the arginase enzymes in allergic airway inflammation. While we will emphasize the ovalbumin exposure mouse model, we will also examine other models. Where inconsistencies are identified among the studies, we attempt to determine whether such inconsistencies arise from methodological differences or alternative mechanisms. Ultimately, we address whether the allergen-exposed mouse is a suitable model for identifying promising new drugs for the treatment of human asthma. While a consensus is building that NO is beneficial or protective in subsets of asthmatics, results from studies using mouse models to investigate the individual roles of NO and the NOS enzymes in airway inflammation are often contradictory. Further research efforts with this model will allow us to distinguish which asthma patients may benefit best from NO donors and which may benefit from NO inhibitors.

Clinical use of nitric oxide donors and L-arginine in obstetrics

Nitric oxide (NO) is a free radical that plays a fundamental role in human physiology, being involved in the homeostasis of different functions. In obstetrics this molecule is determinant in the physiology of labor and cervical ripening; it possibly plays a fundamental role in the etiology of preeclampsia and intrauterine growth restriction, and it could also be utilized in view of its ability to induce smooth muscle relaxation. Several clinical trials have ascertained the ability of the topical application of NO donors to promote cervical ripening, and also labor induction. There is much less evidence on the use of NO donors in the vascular complications of pregnancy, either as prophylactics or therapeutic agents. Due to the capacity of NO to promote relaxation of smooth muscle, NO donors have been employed as tocolytics with performance similar to other agents. Moreover, although anecdotal, the experience of sudden uterine relaxation using NO donors in obstetric emergencies remains of great clinical value.

The NO TRAIL to YES TRAIL in cancer therapy (review)

Treatment of cancer patients with conventional therapies (chemotherapy, hormonal therapy, immunotherapy and radiation) respond initially well and experience prolonged tumor-free survival. However, in many patients tumor recurrences and relapses occur and such tumors exhibit the resistant phenotype i.e. cross-resistance to various cytotoxic and apoptotic agents. Therefore, new therapeutic strategies are currently being explored and are based on a better understanding of the underlying biochemical and molecular mechanisms of tumor cell resistance. Hence, novel sensitizing agents that can modify the tumor dysregulated apoptotic gene products can reverse resistance when used in combination with subtoxic doses of cytotoxic reagents. Targeted anti-tumor therapies are the current choice in the treatment of resistant tumors. One such targeted therapy is the application of TRAIL or TRAIL agonist monoclonal antibodies (mAbs) (anti-DR4 and anti-DR5) because, unlike Fas ligand and TNF-alpha, they are not cytotoxic to normal tissues. TRAIL as monotherapy will only be effective against TRAIL sensitive tumors, however, most tumors are resistant to TRAIL and their sensitization can restore their sensitivity to TRAIL apoptosis. We present, herein, one potential novel sensitizing agent, namely, nitric oxide (NO) that has been shown to sensitize TRAIL-resistant tumor cells to TRAIL apoptosis via its inhibitory effect on the transcription factors NF-kappaB and Yin Yang 1 (YY1), concomitantly with upregulation of DR5. We propose the therapeutic application of NO donors as sensitizing agents used in combination with TRAIL/DR4 or DR5 mAbs in the treatment of TRAIL-resistant tumors.

Development of novel agents based on nitric oxide for the control of colon cancer

Nitric oxide-donating nonsteroidal anti-inflammatory drugs (NO-NSAIDs) represent a novel class of compounds that hold promise as agents for the control of colon cancer. They are derivatives of conventional NSAIDs that have been modified by adding to them, via a spacer molecule, a nitric oxide releasing moiety. The expectation is that the combined effects of NO and the NSAID moiety will exceed those of each structural component alone. Extensive work has demonstrated their potency and efficacy in preclinical models of colon cancer. The mechanism of action of NO-NSAIDs involves the modulation of several critical cellular signaling pathways, whereas the induction of a state of oxidative stress, at least by NO-aspirin, appears to be a major proximal event. Clinical trials are needed to assess the role of NO-NSAIDs in the control of colon cancer.

Novel thromboresistant materials

The development of a clinically durable small-diameter vascular graft as well as permanently implantable biosensors and artificial organ systems that interface with blood, including the artificial heart, kidney, liver, and lung, remain limited by surface-induced thrombotic responses. Recent breakthroughs in materials science, along with a growing understanding of the molecular events that underlay thrombosis, has led to the design and clinical evaluation of a variety of biologically active coatings that inhibit components of the coagulation pathway and platelet responses by surface immobilization or controlled release of bioactive agents. This report reviews recent progress in generating synthetic thromboresistant surfaces that inhibit (1) protein and cell adsorption, (2) thrombin and fibrin formation, and (3) platelet activation and aggregation.

A review of chronic anal fissure management

Anal fissure management has rapidly progressed in the last 15 years as our understanding of fissure pathophysiology has developed. All methods of treatment aim to reduce the anal sphincter spasm associated with chronic anal fissures. Surgical techniques have been used for over 100 years with success. Lateral internal sphincterotomy remains the surgical treatment of choice for many practitioners. Postoperative impairment of continence remains controversial. Recently, less invasive methods of treatment have been explored. Topical nitrates, calcium channel blockers and botulinum toxin are established treatments. These and other non-surgical treatments are described in this review. Various guidelines and treatment algorithms for anal fissure are also discussed.

Interaction of L-Arginine-methyl ester and Sonic hedgehog in liver ischemia-reperfusion injury in the rats

AIM: To investigate the role of Sonic hedgehog (Shh) on the course of liver ischemia and reperfusion (I/R) in rats, and the interaction between treatment with nitric oxide donor L-Arginine-methyl ester (L-Arg) and up-regulation of Shh expression.

METHODS: A total of 30 male Sprague-Dawley rats weighing 220-240 g were used in this study. Sham-control group (G1, n = 10): a sham operation was performed (except for liver I/R). I/R-untreated group (G2, n = 10): rats underwent liver ischemia for 1 h followed by reperfusion for 45 min. I/R-L-Arg group (G3, n = 10): after performing the same surgical procedure as in group 2, animals were treated with L-Arg. Liver tissues were taken for determination of malondialdehyde (MDA) levels, and biochemical and histological evaluations were made.

RESULTS: Plasma alanine aminotransferase (ALT), aspartate aminotransferase (AST), lactate dehydrogenase (LDH) and γ-glutamyltranspeptidase (GGT) activities were higher in group 2 than in group 3. MDA values and the hepatic injury score decreased in the L-Arg treated group compared to the I/R-untreated group. In group 2, the hepatocytes were swollen with marked vacuolization. Group 3 rats showed well-preserved liver parenchyma, with hepatocytes extending from the central vein. The morphology of the hepatocytes and the sinusoidal structures was normal, without any signs of congestion. Mild Shh positive immunostaining was detected in group 2 animals. The expression of immunoreactive cells was increased markedly in liver tissue from I/R-L-Arg rats.

CONCLUSION: Our findings suggest that Shh molecules are critical factors in the pathophysiology of inflammatory liver injury induced by I/R. In addition, NO plays an important role in the immunohistochemical expression of these molecules.

Nitric oxide donor upregulation of stromal cell-derived factor-1/chemokine (CXC motif) receptor 4 enhances bone marrow stromal cell migration into ischemic brain after stroke

Stromal cell-derived factor-1 (SDF1) and its chemokine (CXC motif) receptor 4 (CXCR4), along with matrix metalloproteinases (MMPs), regulate bone marrow stromal cell (BMSC) migration. We tested the hypothesis that a nitric oxide donor, DETA-NONOate, increases endogenous ischemic brain SDF1 and BMSC CXCR4 and MMP9 expression, which promotes BMSC migration into ischemic brain and thereby enhances functional outcome after stroke. C57BL/6J mice were subjected to middle cerebral artery occlusion (MCAo), and 24 hours later, the following were intravenously administered (n = 9 mice per group): (a) phosphate-buffered saline; (b) BMSCs (5 x 10(5)); (c) 0.4 mg/kg DETA-NONOate; (d) combination of CXCR4-inhibition BMSCs with DETA-NONOate; and (e) combination of BMSCs with DETA-NONOate. To elucidate the mechanisms underlying combination-enhanced BMSC migration, transwell cocultures of BMSC with mouse brain endothelial cells (MBECs) or astrocytes were performed. Combination treatment significantly improved functional outcome after stroke compared with BMSC monotherapy and MCAo control, and it increased SDF1 expression in the ischemic brain compared with DETA-NONOate monotherapy and MCAo control. The number of BMSCs in the ischemic brain was significantly increased after combination BMSC with DETA-NONOate treatment compared with monotherapy with BMSCs. The number of engrafted BMSCs was significantly correlated with functional outcome after stroke. DETA-NONOate significantly increased BMSC CXCR4 and MMP9 expression and promoted BMSC adhesion and migration to MBECs and astrocytes compared with nontreatment BMSCs. Inhibition of CXCR4 or MMPs in BMSCs significantly decreased DETA-NONOate-induced BMSC adhesion and migration. Our data demonstrate that DETA-NONOate enhanced the therapeutic potency of BMSCs, possibly via upregulation of SDF1/CXCR4 and MMP pathways, and increased BMSC engraftment into the ischemic brain.

In vitro and in vivo antiproliferative and trypanocidal activities of ruthenium NO donors

BACKGROUND AND PURPOSE

Many compounds liberating NO (NO donors) have been used as therapeutic agents. Here we test two ruthenium nitrosyls, which release NO when activated by biological reducing agents, for their effects in vitro and in vivo against Trypanosoma cruzi, the agent responsible for the American trypanosomiasis (Chagas' disease).

EXPERIMENTAL APPROACH

Ruthenium NO donors were incubated with a partially drug-resistant strain of T. cruzi and the anti-proliferative and trypanocidal activities evaluated. In a mouse model of acute Chagas' disease, trypanocidal activity was evaluated by measuring parasitemia, survival rate of infected mice and elimination of amastigotes in myocardial tissue.

KEY RESULTS

In vitro, the observed anti-proliferative and trypanocidal activities of trans-[Ru(NO)(NH(3))(4)isn](BF(4))(3) and trans-[Ru(NO)(NH(3))(4)imN](BF(4))(3) were due to NO liberated upon reduction of these nitrosyls. Ru(NO)isn had a lower IC(50 epi) (67 microM) than the NO donor, sodium nitroprusside (IC(50 epi)=244 microM) and Ru(NO)imN (IC(50 try)=52 microM) was more potent than gentian violet (IC(50 try)=536 microM), currently used in the treatment of blood. Both ruthenium nitrosyls eliminated, in vivo, extracellular as well as intracellular forms of T. cruzi in the bloodstream and myocardial tissue and allowed survival of up to 80% of infected mice at a dose (100 nmol kg(-1) day(-1)) much lower than the optimal dose for benznidazole (385 micromol kg(-1) day(-1)).

CONCLUSIONS AND IMPLICATIONS

Our data strongly suggest that NO liberated is responsible for the anti-proliferative and trypanocidal activities of the ruthenium NO donors and that these compounds are promising leads for novel and effective anti-parasitic drugs.

Endothelial nitric oxide synthase plays an obligatory role in the late phase of ischemic preconditioning by activating the protein kinase C epsilon p44/42 mitogen-activated protein kinase pSer-signal transducers and activators of transcription1/3 pathway

BACKGROUND

The role of endothelial nitric oxide synthase (eNOS) in ischemic preconditioning (PC) and cardioprotection is poorly understood. We addressed this issue using a genetic, rather than pharmacological, approach.

METHODS AND RESULTS

In the nonpreconditioned state, eNOS-/- mice exhibited infarct sizes similar to those of wild-type mice. A sequence of six 4-minute coronary occlusion/4-minute reperfusion cycles (ischemic PC) induced late PC in wild-type mice; genetic deletion of eNOS abrogated the cardioprotection induced by late PC. In wild-type mice, ischemic PC induced membranous translocation of protein kinase C (PKC) epsilon and an increase in pSer-MEK-1/2 and pTyr-p44/42 mitogen-activated protein kinase, nuclear pSer-signal transducers and activators of transcription (STAT)1 and pSer-STAT3, and nuclear STAT1/3 DNA binding activity, followed by upregulation of cyclooxygenase-2 protein and activity 24 hours later. All of these changes were abrogated in eNOS-/- mice. The NO donor diethylenetriamine/NO recapitulated the effects of ischemic PC.

CONCLUSIONS

In contrast to previous reports, we found that basal eNOS activity does not modulate infarct size in the nonpreconditioned state. However, eNOS is obligatorily required for the development of the cardioprotective effects of late PC and acts as the trigger of this process by activating the PKC epsilon-MEK-1/2-p44/42 mitogen-activated protein kinase pathway, leading to Ser-727 phosphorylation of STAT1 and STAT3 and consequent upregulation of STAT-dependent genes such as cyclooxygenase-2. The effects of eNOS-derived NO are reproduced by exogenous NO (NO donors), implying that nitrates can upregulate cardiac cyclooxygenase-2.

Development of nitric oxide donors for the treatment of cardiovascular diseases

Nitric oxide (NO) is a molecule that dynamically modulates the physiological functions of the cardiovascular system, which include relaxation of vascular smooth muscle, inhibition of platelet aggregation, and regulation of immune responses. Because a reduced NO level has been implicated in the onset and progression of various disease states, NO is expected to provide therapeutic benefits in the treatment of cardiovascular diseases, such as essential hypertension, stroke, coronary artery disease, atherosclerosis, platelet aggregation after percutaneous transluminal coronary angioplasty, and ischemia/reperfusion injury. To date, pharmacologically active compounds that can release NO within the body, such as organic nitrates and sodium nitroprusside, have been used as therapeutic agents, but their efficacy is significantly limited by their rapid NO release, poor distribution to the target site, toxicity, and induction of tolerance. Therefore, new NO donors with better pharmacological and pharmacokinetic properties would be highly desirable. In this review, recent challenges in the development of new NO donors and NO delivery systems are summarized. Then, future developments of novel NO donors are also discussed in order to optimize NO delivery in the treatment of cardiovascular diseases.

Modern perspectives in the treatment of chronic anal fissures

INTRODUCTION

Anal fissures are commonly encountered in routine colorectal practice. Developments in the pharmacological understanding of the internal anal sphincter have resulted in more conservative approaches towards treatment. Simple measures are often effective for early fissures. Glyceryl trinitrate is well established as a first-line pharmacological therapy. The roles of diltiazem and botulinum, particularly as rescue therapy, are not well understood. Surgery has a defined role and should not be discounted completely.

METHODS

Data were obtained from Medline publications citing 'anal fissure'. Manual cross-referencing of salient articles was conducted. We have sought to highlight various controversies in the management of anal fissures.

FINDINGS

Acute fissures may heal spontaneously, although simple conservative measures are sufficient. Idiopathic chronic anal fissures need careful evaluation to decide what therapy is suitable. Pharmacological agents such as glyceryl trinitrate (GTN), diltiazem and botulinum toxin have been subjected to most scrutiny. Though practices in the UK vary, GTN or diltiazem would be suitable as first-line therapy with botulinum toxin used as rescue treatment. Sphincterotomy is indicated for unhealed fissures; fissurectomy has been revisited and advancement flaps have a role in patients in whom sphincter division is not suitable.

Pharmacological evaluation of anti-leishmanial activity by in vivo nitric oxide modulation in Balb/c mice infected with Leishmania major MRHO/IR/75/ER: An Iranian strain of cutaneous leishmaniasis

Cutaneous leishmaniasis with a variation in its clinical signs is still one of the health problems in the world, region and Iran. Immune responses against leishmania consist of cytokines, immune cells and mediators. Macrophages participate actively in the inflammatory response by releasing chemokines and mediators including nitric oxide (NO) and reactive oxygen and nitrogen intermediates. This study investigates whether NO had anti-leishmanial effects and/or mediated pathology in mice infected with Leishmania major MRHO/IR/75/ER (IR/75). NO inducer lipopolysaccharide (LPS) and NO donor S-nitrosoglutathione (SNOG) were used for their ability to increase RNI and to modify leishmania infection in susceptible Balb/c mice, in order to evaluate the effects of NO production on size and lesion macroscopy, delay of lesion formation and proliferation of amastigotes inside macrophages. Liver, spleen and lymph nodes were also studied as target organs to detect amastigotes. In addition to plasma, liver and spleen suspensions were investigated for NO induction by using Griess microassay. Statistical analysis of data revealed an association between increases in NO level with the pathology of disease in Balb/c mice infected with L. major IR/75. The survival of leishmania parasite inside the macrophages and its proliferation was affected by LPS and SNOG-treatments. An inconsistent relationship was evident between the NO modulation and pathological changes in treated Balb/c mice infected with L. major IR/75.

CAN NITRIC OXIDE-GENERATING COMPOUNDS IMPROVE THE OXIDATIVE STRESS RESPONSE IN EXPERIMENTALLY DIABETIC RATS?

1. The present study was designed to evaluate the protective effects of the nitric oxide (NO)-generating compounds L-arginine (L-Arg) and sodium nitroprusside (SNP) on oxidative stress markers in streptozotocin (STZ)-diabetic rats. 2. Diabetes was induced after a single intraperitoneal injection of STZ (60 mg/kg). Rats were divided into non-diabetic (control), diabetic and treated diabetic groups. The treated diabetic groups were supplemented with L-Arg (300 mg/kg), SNP (3 mg/kg per day) or glibenclamide (0.6 mg/kg per day) orally for 4 weeks. 3. At the end of the experiment, fasted rats were killed by cervical decapitation. Blood was collected for estimation of glucose, haemoglobin, glycosylated haemoglobin (HbA(1c)), total cholesterol, high-density lipoprotein-cholesterol and triglycerides. Thiobarbituric acid-reactive substances (TBARS; an index of lipid peroxidation), superoxide dismutase, glutathione peroxidase, catalase, nitrate/nitrite (NO(x)) and reduced glutathione (GSH) were estimated in liver and kidney homogenates. 4. A significant increase was observed in plasma glucose levels and HbA(1c), with a concomitant decrease in haemoglobin levels, in diabetic rats. These alterations reverted back to near normal after treatment with the NO-generating compounds. A loss of bodyweight, polydipsia, polyphagia and elevated levels of serum cholesterol and triglycerides were observed in diabetic rats. Hyperglycaemia was accompanied by a significant increase in tissue TBARS and a decrease in NO(x), GSH and anti-oxidant enzymes, whereas, supplementation with L-Arg and SNP significantly reduced TBARS levels and increased GSH and anti-oxidant enzyme activities. Linear regression analysis indicated that blood glucose and TBARS had a significant positive correlation with HbA(1c), whereas a negative correlation was observed between GSH and NO(x). 5. It is concluded that NO-generating compounds improve most of the biochemical abnormalities and anti-oxidant levels in diabetic rats. The beneficial effects of NO-generating compounds can be attributed to the generation of NO and/or enhanced anti-oxidant enzyme activities.

Systemic Inflammatory Response, Bacterial Translocation and Nitric Oxide Donors

Abdominal aortic surgery is relatively common and is associated with considerable post-operative morbidity and death. The aortic cross-clamping (supra or infrarenal) necessary for the insertion of a vascular graft, often in circumstances of haemorrhagic shock (e.e. a ruptured aneurysm) elicits a Systemic Inflammatory Response Syndrome (SIRS) and an Ischaemia-Reperfusion syndrome (I-R), with affectation of many organs including the kidneys and the intestine. Experimentally, the exogenous use of nitric oxide donors has proved to be able to control the SIRS, minimising the damage due to I-R and protecting from renal dysfunction and BT. However, clinical experience in these situations is still limited. Here we review the current status and experience of the authors in the use of nitric oxide donors in the control of the SIRS induced by infrarenal, suprarenal aortic cross-clamping, with or without haemorrhagic shock; and the Bacterial Translocation phenomenon (BT) induced by aortic cross-clamping below the mesenteric artery with or without associated hemorrhaging.

The role of nitric oxide in the pathophysiology of intimal hyperplasia

Since its discovery, nitric oxide (NO) has emerged as a biologically important molecule and was even named Molecule of the Year by Science magazine in 1992. Specific to our interests, NO has been implicated in the regulation of vascular pathology. This review begins with a summary of the molecular biology of NO, from its discovery to the mechanisms of endogenous production. Next, we turn our attention to describing the arterial injury response of neointimal hyperplasia, and we review the role of NO in the pathophysiology of neointimal hyperplasia. Finally, we review the literature regarding NO-based therapies. This includes the development of inhalational-based NO therapies, systemically administered L-arginine and NO donors, NO synthase gene therapy, locally applied NO donors, and NO-releasing prosthetic materials. By reviewing the current literature, we emphasize the tremendous clinical potential that NO-based therapies can have on the development of neointimal hyperplasia.

Botulinum toxin A injection in ISDN ointment-resistant chronic anal fissures

BACKGROUND

In the treatment of chronic anal fissures (CAFs), surgical sphincterotomy is more commonly being replaced by chemical sphincterotomy. After the good results of our pilot study including 32 patients, we now describe the effect of botulinum toxin A (BT-A) in a consecutive series of 100 patients with isosorbide dinitrate (ISDN) ointment-resistant CAFs.

METHODS

From October 2002 until August 2005, 100 patients (52 males, 48 females) with a median age of 45 (20-79) years were treated with an injection of 40-100 IU BT-A (Dysport, Ipsen, The Netherlands) in the internal anal sphincter.

RESULTS

After a median follow-up of 10 (4-38) months, 77 of the 100 CAFs (77%) were cured. 20 patients were given a second injection, 1 a third and 1 a fourth injection. In 11 patients a fissure recurred (14%). In 1 patient (1%) there was temporary incontinence due to flatus.

CONCLUSION

With an early response rate of 77% and an overall success rate of 66%, BT-A injections appear to be effective in patients with ISDN ointment-resistant CAFs if initial non-responders are retreated. These results are in concordance with the results of our pilot study. It is a simple technique with little or no side effects, that does not compromise future treatments. Its place in the first-line treatment of CAFs should be investigated further.

[Effect of the nitric oxide donors Na nitroprusside and L-arginine on the course of uveitis, the antioxidative and antiproteolytic potential of tear and blood in the experiment]

The nitric oxide (NO) donors Na nitroprusside and L-arginine were tested for their effects on the course of experimental immunogenic uveitis, antiproteolytic and antioxidative activities in the rabbit tear and blood. With the use of the NO donors, the course of uveitis was shown to be more severe and prolonged. In uveitis, there was a change in the activity of the antiproteinases--alpha1-antitrypsin and alpha2-macroglobulin and the antioxidative enzymes superoxide dismutase in both tear and blood. The magnitude of changes in the biochemical parameters under study suggested that the course of uveitis was more severe in the rabbits given the NO donors. Thus, the inclusion of the NO donors in the active phase enhances an inflammatory reaction in immunogenic uveitis.

Nitric oxide for preventing pre-eclampsia and its complications

BACKGROUND

Pre-eclampsia, a multisystem disorder of pregnancy characterised by high blood pressure and protein in the urine, is associated with endothelial dysfunction. Nitric oxide mediates many functions of the endothelium, including vasodilatation and inhibition of platelet aggregation. Pre-eclampsia may be associated with nitric oxide deficiency, but the evidence to support this suggestion is contradictory. Nevertheless, it has been hypothesised that agents which increase nitric oxide may prevent pre-eclampsia.

OBJECTIVES

To assess the effectiveness and safety of nitric oxide donors and precursors for preventing pre-eclampsia and its complications.

SEARCH STRATEGY

We searched the Cochrane Pregnancy and Childbirth Group's Trials Register (November 2006), CENTRAL (The Cochrane Library 2006, Issue 3), and EMBASE (2002 to December 2004).

SELECTION CRITERIA

Studies were included if they were randomised trials evaluating nitric oxide donors or precursors for preventing pre-eclampsia and its complications.

DATA COLLECTION AND ANALYSIS

Both review authors independently assessed studies for inclusion. Data were extracted and double checked for accuracy.

MAIN RESULTS

Six trials (310 women) were included. Four were of good quality and two were of uncertain quality. Four trials (170 women) compared nitric oxide donors (glyceryl trinitrate) or precursors (L-arginine) with either placebo or no intervention. There are insufficient data for reliable conclusions about the effects on pre-eclampsia (four trials, 170 women; relative risk (RR) 0.83, 95% confidence interval (CI) 0.49 to 1.41) or its complications. One trial (36 women) compared a nitric oxide donor with nifedipine, and another (76 women) compared it with antiplatelet agents. Both were too small for reliable conclusions about possible differential effects. Glyceryl trinitrate was associated with an increased risk of headache (two trials, 56 women; RR 6.85, 95% CI 1.42 to 33.04), and of stopping treatment (two trials, 56 women; RR 4.02, 95% CI 1.15 to 14.09) compared to placebo. However, the increase for both outcomes was due to an extreme result in one small trial (7/7 versus 0/9 for both outcomes).

AUTHORS' CONCLUSIONS

There is insufficient evidence to draw reliable conclusions about whether nitric oxide donors and precursors prevent pre-eclampsia or its complications.

Nitric oxide mediates cardiovascular symptoms in alcohol withdrawal

We studied whether nitric oxide is involved in cardiovascular symptoms in alcohol withdrawal. Cardiovascular effects of isosorbide dinitrate (ISDN; 20 mg sublingually), a nitric oxide donor were compared in 21 alcohol-dependent subjects during alcohol withdrawal (n=11) on days 1, 2, 3, and 10 to those during remission (n=10; duration=60.7+/-10.5 days). Cardiovascular parameters were measured non-invasively. The levels of systolic and diastolic blood pressure, total peripheral resistance were significantly higher in patients with withdrawal than in remission. Same cardiovascular parameters showed different response to ISDN during withdrawal when compared to remission. The differences were largest during the initial phase (1-2 days) of withdrawal. Nitric oxide may mediate at least some cardiovascular symptoms in withdrawal.

Sexual function in hypertensive patients receiving treatment

In many forms of erectile dysfunction (ED), cardiovascular risk factors, in particular arterial hypertension, seem to be extremely common. While causes for ED are related to a broad spectrum of diseases, a generalized vascular process seems to be the underlying mechanism in many patients, which in a large portion of clinical cases involves endothelial dysfunction, ie, inadequate vasodilation in response to endothelium-dependent stimuli, both in the systemic vasculature and the penile arteries. Due to this close association of cardiovascular disease and ED, patients with ED should be evaluated as to whether they may suffer from cardiovascular risk factors including hypertension, cardiovascular disease or silent myocardial ischemia. On the other hand, cardiovascular patients, seeking treatment of ED, must be evaluated in order to decide whether treatment of ED or sexual activity can be recommended without significantly increased cardiac risk. The guideline from the first and second Princeton Consensus Conference may be applied in this context. While consequent treatment of cardiovascular risk factors should be accomplished in these patients, many antihypertensive drugs may worsen sexual function as a drug specific side-effect. Importantly, effective treatment for arterial hypertension should not be discontinued as hypertension itself may contribute to altered sexual functioning; to the contrary, alternative antihypertensive regimes should be administered with individually tailored drug regimes with minimal side-effects on sexual function. When phosphodiesterase-5 inhibitors, such as sildenafil, tadalafil and vardenafil, are prescribed to hypertensive patients on antihypertensive drugs, these combinations of antihypertensive drugs and phosphodiesterase 5 are usually well tolerated, provided there is a baseline blood pressure of at least 90/60 mmHg. However, there are two exceptions: nitric oxide donors and α-adrenoceptor blockers. Any drug serving as a nitric oxide donor (nitrates) is absolutely contraindicated in combination with phosphodiesterase 5 inhibitors, due to significant, potentially life threatening hypotension. Also, α-adrenoceptor blockers, such as doxazosin, terazosin and tamsulosin, should only be combined with phosphodiesterase 5 inhibitors with special caution and close monitoring of blood pressure.

African American heart failure trial: role of endothelial dysfunction and heart failure in African Americans

Heart failure (HF) in African Americans may have differences in etiology and drug response. Compared with coronary disease in whites, HF in African Americans is marked by increased prevalence, earlier onset, increased risk for hospitalization and mortality, and increased prevalence of hypertension as the underlying cause of disease. There are apparent differences in pathophysiology and response to cardiac drugs. Endothelial dysfunction is potentially among the hallmarks of HF in this population, with diminished release of nitric oxygen (NO), increased inactivation of NO caused by increased oxidant stress, and impaired antioxidant defenses. Novel approaches to HF in African Americans include the use of isosorbide dinitrate combined with hydralazine in a fixed-dose formulation, which may affect endothelial dysfunction and the relative contribution of NO deficiency in this population. The African American Heart Failure Trial (A-HeFT) demonstrated improvement in morbidity and mortality, including a 39% reduction in hospitalization, improvement in quality of life or functional status, and a 43% reduction in mortality. When added to standard therapy, isosorbide dinitrate and hydralazine provide an evidence-based approach to diminishing morbidity and mortality in this high-risk population.

From hypertension to heart failure: role of nitric oxide-mediated endothelial dysfunction and emerging insights from myocardial contrast echocardiography

There is growing evidence that nitric oxide (NO)-mediated endothelial dysfunction occurs in hypertension and may represent the earliest stage of target organ damage, which ultimately leads to hypertensive heart disease and heart failure (HF). An understanding of how impaired myocardial microvascular function and flow reserve relate to early remodeling during the transition to HF in patients with hypertension may lead to new therapeutic insights. The hypertrophied heart, which is a feature of the adverse structural remodeling in hypertensive heart disease, may be accompanied by impaired coronary flow reserve (CFR). Reduced CFR could potentially cause subendocardial ischemia during conditions of high metabolic demand, such as uncontrolled hypertension and tachycardia. Such vulnerability of the subendocardium to abnormal perfusion or ischemia may accelerate the progression from compensated hypertrophy to HF. In this review, we discuss preliminary evidence that altered NO balance may contribute to cardiac hypertrophy-mediated myocardial ischemia. We also describe early results with myocardial contrast echocardiography in the postulated transition from compensated hypertrophy to cardiac failure. These data support further evaluation of NO mediators as potential targets for novel therapies in hypertensive heart disease.

Early and sustained benefit on event-free survival and heart failure hospitalization from fixed-dose combination of isosorbide dinitrate/hydralazine: consistency across subgroups in the African-American Heart Failure Trial

BACKGROUND

We previously reported that the fixed-dose combination of isosorbide dinitrate and hydralazine hydrochloride (FDC I/H) significantly decreased the risk of all-cause death and first hospitalization for heart failure (HF) and improved quality of life in patients with New York Heart Association class III or IV heart failure in the African-American Heart Failure Trial (A-HeFT). The current analyses further define the effect of FDC I/H on the timing of event-free survival (mortality or first hospitalization for HF) and time to first hospitalization for HF, as well as effects by subgroups and effects on cause-specific mortality.

METHODS AND RESULTS

Kaplan-Meier analyses of the 1050 A-HeFT patients on standard neurohormonal blockade demonstrated that FDC I/H produced a 37% improvement in event-free survival (P<0.001) and a 39% reduction in the risk for first hospitalization for HF (P<0.001). These benefits appeared to emerge early (at approximately 50 days of treatment) and were sustained through the duration of the trial. Subgroup analyses of treatment effect by age, sex, baseline blood pressure, history of chronic renal insufficiency, presence of diabetes mellitus, cause of HF, and baseline medication usage demonstrated consistent beneficial effect of FDC I/H on the primary composite score and event-free survival across all subgroups. Mortality from pump failure was reduced by 75% (P=0.012).

CONCLUSIONS

FDC I/H treatment of black patients with moderate to severe HF who were taking neurohormonal blockers produced early and sustained significant improvement in event-free survival and hospitalization for HF in the A-HeFT cohort, with significant reduction in mortality from cardiovascular and pump failure deaths. The treatment effects on the primary composite end point and event-free survival were consistent across subgroups.

Prevention by NCX 4016, a nitric oxide-donating aspirin, but not by aspirin, of the acute endothelial dysfunction induced by exercise in patients with intermittent claudication

Ischemia/reperfusion damage evokes systemic inflammation and endothelial dysfunction in patients with intermittent claudication. We compared the effects of aspirin with those of a nitric oxide-donating aspirin in preventing the acute, systemic endothelial dysfunction provoked by exercise-induced ischemia of the lower limbs in patients with intermittent claudication. In a prospective, randomized, single-blind, parallel-groups trial among 44 patients with intermittent claudication we compared four weeks of aspirin (100 mg o.d.) with NCX 4016 (800 mg b.i.d.). Primary end point was the exercise-induced changes in brachial flow-mediated vasodilation (FMD) at day 28; secondary end points were effort-induced changes of markers of neutrophil (plasma elastase) and endothelial (soluble VCAM-1) activation. Baseline FMD was comparable in the two groups, both on day 1 (pre-treatment: aspirin = 3.1 +/- 0.5%, nitroaspirin = 3.9 +/- 0.7%, p = NS), and on day 28 (aspirin = 3.4 +/- 0.7%, NCX 4016 = 3.2 +/- 0.6%, p = NS). Maximal treadmill exercise induced an acute worsening of FMD in both groups at baseline (aspirin = -1.15%, nitroaspirin = -1.76%); after four weeks treatment, the impairment of FMD induced by exercise was still present in the aspirintreated group (-1.46%) while it was abolished in the NCX 4016-treated group (+0.79%, p = 0.038 vs. aspirin). Similarly, exercise induced an increase of plasma elastase and of sVCAM-1 which were not affected by aspirin while they were suppressed by NCX 4016. Maximal treadmill exercise induces a systemic arterial endothelial dysfunction in patients with intermittent claudication. A nitric oxide-donating aspirin, but not aspirin, prevents effort-induced endothelial dysfunction.

The nitric oxide donor LA 419 decreases brain damage in a focal ischemia model

Stroke affects a large number of people, especially in developed countries, but treatment options are limited. Over the years, it has become clear that nitric oxide (NO) plays a major role in this pathology and that treatments that either reduce or increase NO presence may provide an alternative route for reducing the sequelae of brain ischemia. The NO donor LA 419 previously has been shown to protect the brain tissue from ischemic damage in an experimental model of global brain ischemia. Here we study whether this holds true for focal ischemia, a condition closer to the more common form of human stroke. Ischemia was induced in rats by a stereotaxic injection of endothelin-1, a potent vasoconstrictor, in the striatum. Seven days after the injection, magnetic resonance imaging (MRI) found a significant elevation in apparent diffusion coefficient (ADC) in the injected striatum of untreated rats, due to ischemia-induced vascular edema. Animals that received LA 419 prior to injection with endothelin-1 showed an ADC undistinguishable from the contralateral striatum or from the striatum of rats not treated with LA 419. In addition, immunohistochemistry with antibodies against neuronal nitric oxide synthase (nNOS), inducible NOS (iNOS), and nitrotyrosine showed a marked increase in the expression of these markers of NO production following ischemic treatment that was dampened by treatment with LA 419. In summary, our results clearly show that the NO donor LA 419 may be a useful compound for the prevention and/or treatment of focal brain ischemia.

[Perspectives in the treatment of subarachnoid-hemorrhage-induced cerebral vasospasm]

Cerebral vasospasm is still the most important cause of death and disability after rupture of intracranial aneurysms. The therapeutic strategies in the treatment of subarachnoid hemorrhage induced vasospasm vasospasm include four groups: 1) prevention of vasospasm; 2) reversion of vasospasm; 3) improvement of cerebral perfusion; and 4) neuroprotection and rescue therapies. Recent experimental studies allowed the design of phase II clinical studies which demonstrated positive results with medications and compounds such as statins (simvastatin and pravastatin) and endothelin-1 receptor antagonists (clasozentan). Moreover, experimental and clinical evidences showed the advantages of early cerebrospinal fluid drainage, intrathecal administration of NO-donors, effects of Ca2+ protein kinase inhibitor (Fasudil) and catecholamines on the cerebral vessels. This review article summarizes the stage of investigation of these medications and therapeutic strategies which will be relevant in the treatment of cerebral vasospasm.

Cyclo-Oxygenase (COX) Inhibiting Nitric Oxide Donating (CINODs) Drugs: A Review of Their Current Status

Non-steroidal anti-inflammatory drugs (NSAIDs) are widely used drugs but their use is hampered by gastrointestinal side effects. Cyclo-oxygenase Inhibitor Nitric Oxide Donors (CINODs) are a new class of anti-inflammatory and analgesic drugs generated by adding a nitric oxide generating moiety to the parent NSAID via an ester linkage. The combination of balanced inhibition of the two main COX isoforms with release of NO confers to CINODs a reduced gastrointestinal toxicity and a potent anti-inflammatory activity. It is suggested that the NO, which is released by the metabolism of nitrate as the compounds are broken down, may counteract the consequences of the NSAID-induced decrease in gastric mucosal prostaglandins. Recent clinical trials with CINODs (previously termed NO-NSAIDs) have provided data consistent with pre-clinical observations.