Progress in the understanding and treatment of chronic anal fissure

BACKGROUND

Chronic anal fissure is a common and painful condition associated with internal anal sphincter hypertonia. Reduction of this hypertonia improves the local blood supply, encouraging fissure healing. Surgical sphincterotomy is very successful at healing these fissures but requires an operation with associated morbidity. Temporary reduction in sphincter tone can be achieved on an outpatient basis by applying a topical nitric oxide donor (for example, glyceryl trinitrate) or injecting botulinum toxin into the anal sphincter.

METHODS

A Medline database was used to perform a literature search for articles relating to the non-surgical treatment of chronic anal fissure.

RESULTS

Review of the literature shows botulinum toxin injection to be more effective at healing chronic anal fissures than topical glyceryl trinitrate. Topical isosorbide dinitrate has not been directly compared with either of these two agents but has a healing rate approaching that of botulinum toxin injection. The main side effect of botulinum toxin injection is temporary faecal incontinence in approximately 2% of cases, whereas topical nitrates cause headaches in 20%-100% of cases. No long term side effects were identified with any of the medical treatments.

CONCLUSION

Chemical sphincterotomy is an effective treatment for chronic anal fissure and has the advantages over surgical treatment of avoiding long term complications (notably incontinence) and not requiring hospitalisation.

Acute and subacute toxicity and efficacy of S-nitrosylated captopril, an ACE inhibitor possessing nitric oxide activities

The toxicity and efficacy of S-nitrosocaptopril (CapNO), a novel vasodilator possessing the capacities of both a nitric oxide donor and an angiotensin converting enzyme (ACE) inhibitor, were examined in rodents. In single-dose acute toxicity studies in ICR mice, the median lethal dose (LD(50)) for CapNO was 674+/-94 mg/kg (iv) and 2078+/-100 mg/kg (po), whereas for oral captopril was 4286+/-173 mg/kg. S-nitrosoglutathione, containing the same S-nitroso moiety as CapNO, showed an LD(50) equal to CapNO when the values were expressed by the mol/kg. The cause of acute death by the high doses of CapNO was lethal hypotension. In the subacute toxicity studies, oral CapNO was well tolerated in normotensive and hypertensive rats at doses up to 500 mg/kg/day for 3 months, except for considerable reductions in food consumption and growth rate observed in the 500 mg/kg/day group. Serum chemistry and hematology tests performed in the subacute toxicity studies revealed no adverse effects of oral CapNO except for a significant decrease in cholesterol levels in hypertensive SHR rat. At autopsy, no histopathological changes in major organs were observed over the subacute period. Administration of a therapeutic dose of CapNO (iv, 250 microg/kg which produced 25% decreases in blood pressure) revealed no changes in the hematological parameters. Subchronic treatment of SHR and SS/Jr rats with oral CapNO (50 mg/kg/day) significantly reduced mean arterial pressure to the normotensive level. Considering the absence of adverse effects of CapNO in the subchronic toxicity study, CapNO appears to be a safe drug for further clinical trials, but particular caution must be taken because it can cause hypotension when overdosed.

[Pulmonary hypertension: the role of nitric oxide in adults]

The human body releases endogenous nitric oxide (NO) from three main sources: neurons, inflammatory processes (induced NO) and endothelium. The chemical industry produces NO by reacting sulfur dioxide and nitric acid, or sodium nitrite and sulfuric acid, or by oxidation of ammonia. Inhaled NO acts on smooth muscle cells of the pulmonary endothelium, causing relaxation by stimulation of guanylate-cyclase. The short half life of NO and its immediate breakdown into hemodynamically inactive but toxic metabolites make this drug a selective pulmonary vasodilator that can decrease pulmonary arterial pressure, improving right ventricular ejection fraction while decreasing intrapulmonary shunt and improving oxygenation.NO has demonstrated its usefulness in treating right ventricular failure secondary to pulmonary hypertension after heart surgery, especially in the transplanted patient. Doses have usually ranged from 5 to 20 parts per million. However, great individual variability in response to NO has been reported. Between 30 and 40% of patients do not respond to treatment. NO is also used to assess the reversibility of chronic pulmonary hypertension in patients who are candidates for heart transplants. Other uses have been suggested, such as reversion of pulmonary vasoconstriction induced by protamine. Applications are limited by the toxicity of metabolites and by route of administration.

Changes in coronary vessel resistance during postischemic reperfusion and effectiveness of nitroglycerin

OBJECTIVE

Microvascular incompetence after ischemia and reperfusion may compromise the normal postischemic coronary perfusion and additionally jeopardize the recovery of the myocytes. We investigated whether such a form of acute endothelial dysfunction occurs in the routine operative setting despite the use of protective measures. For this purpose, we measured pressure-flow relations in the coronary vasculature during heart operations before and after ischemia and after reperfusion and their reaction to the nitric oxide donor nitroglycerin.

METHODS

Forty-eight patients with a low risk profile scheduled for routine coronary artery bypass surgery were included. During normothermic extracorporeal circulation, the fibrillating heart was completely excluded from bypass by clamping of the ascending aorta and snaring of the caval veins. It was relieved of blood by opening the right atrium and venting the left atrium and ventricle to avoid distention. The coronary vessels were perfused under controlled flow, and the perfusion pressures were monitored. This protocol was performed in 24 patients before and immediately after ischemia and after a reperfusion period.

RESULTS

Compared with the preischemic control, vascular resistance was decreased by 17% (P <.003) immediately after ischemia but increased again by 46% (P <.0001) during an average of 25 minutes of reperfusion and, even more important, by 23% (P <.028) in comparison with the preischemic values. In two groups of 12 patients, nitroglycerin was added to the perfusate either in a dosage of 3 microg. kg. min(-1) or as a bolus injection of 2 mg. Low-dose nitroglycerin did not reduce the elevated postreperfusion resistances significantly, but bolus injection did (P <.0002). Coronary vessel resistance increased during reperfusion in particular in patients with a history of hypertension.

CONCLUSION

Coronary vasoconstriction during postischemic reperfusion is regularly present in the routine operative setting in cardiac surgery, despite myocardial protection measures. The amount of vasoconstriction varies considerably and is particularly increased in patients with hypertension. The nitric oxide donor nitroglycerin can normalize the elevated resistances, but only in high dosages. This demonstrates a preserved ability of vascular smooth muscle to relax. The phenomenon had no sequelae in our low-risk patients having elective operations. However, it may gain significance in the case of severe left heart hypertrophy and in patients at risk with both a postoperative low-output syndrome and reduced mean arterial pressures during reperfusion.

Cerebrovascular dysfunction after subarachnoid haemorrhage: novel mechanisms and directions for therapy

1. When a cerebral aneurysm ruptures, bleeding and clot formation occur around the surface of the brain, including several major blood vessels. The resulting condition, known as subarachnoid haemorrhage (SAH), often results in death or severe disability and is a significant cause of stroke. Delayed cerebral vasospasm and impaired vasodilatation are critical clinical complications that occur after SAH. Mechanisms contributing to the development of vasospasm and abnormal reactivity of cerebral arteries after SAH have been intensively investigated in recent years. The present short review briefly decribes recent advances in our knowledge of two relatively novel aspects of the mechanism(s) underlying the vascular abnormalities following SAH. 2. Cerebral arteries are depolarized after SAH, possibly due to decreased activity of potassium channels in vascular muscle. Decreased basal activation of potassium channels may be due to several mechanisms, including impaired activity of nitric oxide (NO). Vasodilator drugs that produce hyperpolarization, such as potassium channel openers, appear to be particularly effective for dilating cerebral arteries after experimental SAH. 3. Subarachnoid haemorrhage often involves decreased responsiveness of cerebral arteries to NO. This could be due to impaired activity of soluble guanylate cyclase, resulting in reduced basal levels of cGMP in cerebral vessels. However, an alternative explanation is that there may be an increased rate of cGMP hydrolysis by phosphodiesterase (PDE)-V in the cerebral vascular wall and that this abnormality contributes substantially to the impairment of NO-mediated cerebral vasodilatation after SAH. In support of this proposal, vasodilator responses to NO are reported to be normalized when coadministered with a PDE-V inhibitor following experimental SAH. 4. Thus, in cerebral vascular muscle after SAH, abnormalities of vasodilator mechanisms involving potassium channel function and also NO/cGMP activity may contribute to cerebral vascular dysfunction. These mechanisms may also represent useful and novel therapeutic targets for the treatment of vasospasm.

A nitric oxide donor induces neurogenesis and reduces functional deficits after stroke in rats

The adult rodent brain is capable of generating neuronal progenitor cells in the subventricular zone, and in the dentate gyrus of the hippocampus, throughout the life of the animal. Signals that regulate progenitor cell proliferation, differentiation, and migration are not well known. We report that administration of a nitric oxide donor, (Z)-1-[N-(2-aminoethyl)-N-(2-ammonioethyl) aminio]diazen-1-ium-1,2-diolate (DETA/NONOate), to young adult rats significantly increases cell proliferation and migration in the subventricular zone and the dentate gyrus. Treatment with DETA/ NONOate also increases neurogenesis in the dentate gyrus. Furthermore, administration of DETA/NONOate to rats subjected to embolic middle cerebral artery occlusion significantly increases cell proliferation and migration in the subventricular zone and the dentate gyrus, and these rats exhibit significant improvements of neurological outcome during recovery from ischemic stroke. Administration of DETA/NONOate significantly increases cortical levels of guanosine monophosphate both in ischemic and nonischemic rats, supporting the role of nitric oxide in promoting cell proliferation and neurogenesis. Thus, our data indicate that nitric oxide is involved in the regulation of progenitor cells and neurogenesis in the adult brain. This suggests that nitric oxide delivered to the brain well after stroke may have therapeutic benefits.

Protective effects of FK409, a novel nitric oxide donor, against postischemic myocardial dysfunction in guinea-pig hearts

Effects of FK409 were investigated in perfused guinea-pig Langendorff hearts subjected to ischemia and reperfusion. Nitric oxide electrode, fluorometry, and 31P nuclear magnetic resonance imaging were used to monitor changes in cellular high-phosphorous energy and nitric oxide and Ca2+ content in the heart together with simultaneous recordings of left ventricular developed pressure. After cardioplegic arrest with St. Thomas' Hospital solution, normothermic (37 degrees C) global ischemia was induced for 40 min, and hearts were reperfused for 40 min. FK409 at 10(-8) M, which has a minimum inotropic effect on nonischemic hearts, was added to the cardioplegic solution. Treatment with FK409 reduced left ventricular developed pressure during and after ischemia and improved postischemic recovery of left ventricular developed pressure from 55.4% at 40 min of reperfusion in FK409-free hearts up to 80.4% in hearts treated with FK409 (p < 0.01). Flow rate at 1.5 min after treatment with the cardioplegic solution was 27.7 ml/min in hearts treated with FK409 compared with 21.2 ml/min in drug-free hearts (p < 0.01). Treatment with FK409 significantly effected preservation of tissue level of beta-adenosine triphosphate at the end of ischemia or reperfusion. During ischemia, arrested with the cardioplegic solution, intracellular Ca2+ accumulation and nitric oxide release were reduced. At the end of ischemia in FK409-treated hearts, nitric oxide release was 86% greater than in drug-free hearts without reference to the Ca2+ concentration. In cardiac surgery, normothermic arrested hearts are subject to damage by oxygen free radicals in reperfusion injury. Therefore, nitric oxide exogenously supplied by FK409 was responsible for the cardioprotective action, presumably by acting directly as an oxygen radical scavenger during reperfusion. A specific nitric oxide donor, like FK409, may have therapeutic use as a nitric oxide-mediated vasorelaxant and additional protective action for reperfusion-injury hearts.

Nitric oxide: implications for vascular and endovascular surgery

Nitric oxide has a key role in vascular homeostasis. It plays a protective role by suppressing abnormal proliferation of vascular smooth muscle following various pathological situations including atherosclerosis and restenosis after vascular interventions such as balloon angioplasty, stent deployment and bypass grafting. It also has strong antiplatelet and anti-thrombogenic properties. In this review, possible applications to daily vascular and endovascular surgery practice, including systemic use of NO donors, enhancing endogenous production of NO by L-arginine and gene therapy, local delivery strategies and coating stents and grafts with NO-delivering/enhancing chemicals are reviewed.

New developments in the management of preterm labor

Current management of preterm labor has not changed the incidence of preterm delivery; therefore, significant research effort has been concentrated on the search for new methods of management. New tocolytics like inhibitors of cyclooxygenase 2 and nitric oxide donors have been tested in animal models and in preliminary clinical trials with promising results. Inhibition of cervical ripening may be one alternative to tocolysis. This new approach has a potential to be a valuable method of management of preterm labor if human studies confirm the promising results reported in animals. Growing evidence suggests that premature delivery may be associated with infection or fetal growth abnormalities, with dire consequences to the fetus. If these associations are to be included in risk and benefit assessment, then inhibition of preterm labor may prove to be detrimental to the fetus.

Relation of cyclic nucleotide ratios to ischemic and reperfusion injury in nitric oxide-donor treated rat hearts

Nitric oxide (NO) donors given during ischemia possibly protect the myocardium by increasing tissue cyclic guanosine monophosphate (cGMP) and decreasing cytosolic Ca2+ levels. However, NO donors also elevate ischemic cyclic adenosine monophosphate (cAMP) levels, which exacerbates ischemic-reperfusion injury. The authors propose that suppression of this NO donor-induced increase in cAMP would improve the cardioprotective properties of these compounds. Langendorff perfused rat hearts were treated with sodium nitroprusside (SNP, 0.1 mM ) or glyceryl trinitrate (GTN, 1.0 microM ) and/or adenylyl cyclase (SQ, 50 microM ) or guanylyl cyclase (ODQ, 30-300 microM ) inhibitors during 40-min low-flow (0.2 ml/min) ischemia. Control reperfusion rate-pressure product (RPP) recoveries were 47 +/- 3% (n = 9) and improved to 59 +/- 1% (n = 11) (p < 0.05) with SNP treatment. Ischemic ODQ treatment decreased RPP recovery to 33 +/- 3% (n = 10) (p < 0.05). ODQ eliminated the cardioprotective effects of SNP (RPP recovery: 40 +/- 5% [n = 7] vs. 59 +/- 1% [p < 0.05]). Adenylyl cyclase inhibition improved RPP recovery from 59 +/- 1% (SNP) to 72 +/- 4% (SNP + SQ) (n = 11) (p < 0.05). The authors conclude that (a) suppression of the NO donor-induced elevations in ischemic cGMP levels (ODQ) worsened reperfusion RPP, (b) suppression of the NO donor-induced elevation in ischemic cAMP levels (SQ) further improved reperfusion RPP in NO donor-treated hearts, and (c) the severity of ischemic-reperfusion injury in the NO donor-treated heart was inversely related to ischemic-tissue cGMP levels and often directly related to the ischemic-tissue cAMP-to-cGMP ratio.

Novel nitric oxide donor (FK409) ameliorates liver damage during extended liver resection with warm ischemia in dogs

BACKGROUND

Nitric oxide attenuates ischemia-reperfusion injury by maintaining organ circulation through its actions as a vasoregulator, an inhibitor of platelet aggregation, and an attenuator of leukocyte adhesion. Otherwise, the harmful effects of enhanced nitric oxide production induced by inducible nitric oxide synthase mediate ischemia-reperfusion injury. FK409 has been characterized as a spontaneous nitric oxide donor. The aim of this study was to evaluate the effects of FK409 on extended liver resection with ischemia using a canine model.

STUDY DESIGN

Adult mongrel dogs were subjected to 60 minutes of warm ischemia by partial inflow occlusion. After reperfusion the nonischemic lobes were resected and the remnant liver function was evaluated. The dogs were divided into two groups: the control group (n = 7) and the FK409 group (n = 6), which was given FK409 through the portal vein.

RESULTS

The hepatic tissue blood flow, serum liver enzymes levels, and serum endothelin-1 level after reperfusion were significantly better in the FK409 group than in the control group. Electron microscopy demonstrated that endothelial cells and Ito cells were well-preserved in the FK409 group. The 3-day survival rate was statistically better in the FK409 group (67%) than in the control group (14%).

CONCLUSIONS

FK409 appears to have protective effects during extended liver resection with ischemia.

The effect of transdermal glyceryl trinitrate, a nitric oxide donor, on blood pressure and platelet function in acute stroke

BACKGROUND AND PURPOSE

Hypertension is a common medical complication in acute stroke and is associated with a poor outcome. However, no large trials have assessed the effect of lowering blood pressure (BP) on outcome, and it remains unclear how BP should be managed in acute stroke. We assessed, in a double-blind randomised controlled trial, whether the nitric oxide (NO) donor glyceryl trinitrate (GTN, a known systemic and cerebral vasodilator), would lower BP and alter platelet function.

METHODS

Thirty-seven patients with recent (< 5 days) ischaemic or haemorrhagic stroke were randomised by minimisation to 12 days of daily treatment with transdermal GTN or matching placebo patches. Twenty-four-hour ambulatory BP was measured before and during GTN treatment at days 0, 1 and 8. Platelet aggregation and expression of adhesion molecules were assessed at the same time points. Functional outcome (Rankin scale) and case fatality were assessed at 3 months. Analysis was by intention-to-treat.

RESULTS

GTN significantly lowered BP by 13.0/5.2 mm Hg at day 1 and 9.3/5.0 mm Hg at day 8. The lesser reduction at day 8 than day 1 suggests that tolerance to GTN was developing. Non-significant falls of 0.9/0.6 and 3.8/0.0 mm Hg occurred at days 1 and 8, respectively, in the placebo group. GTN had no effect on heart rate, or platelet aggregation or expression of platelet adhesion molecules, including glycoproteins Ia, Ib, IIIa and P-selectin. Additionally, GTN did not alter case fatality or dependency, although the study was not powered for these outcomes.

CONCLUSIONS

Transdermal GTN, an NO donor, lowered BP by 5-8%, a clinically significant and relevant, but not excessive, degree in patients with acute stroke. However, GTN had no effect on platelet aggregation or expression of adhesion molecules. Since NO donors increase cerebral blood flow in patients with acute ischaemic stroke, GTN may be an appropriate drug for testing the effect of lowering BP on functional outcome.

Susceptibility to cerulein-induced pancreatitis in inducible nitric oxide synthase-deficient mice

Production of nitric oxide (NO) by inducible nitric oxide synthase (iNOS) has been proposed as a pathogenic factor in acute pancreatitis, but its role has still not been fully examined. The present study explored the role of iNOS in cerulein-induced acute pancreatitis using iNOS-deficient mice. Twelve- to 14-week-old male mice (C57B1/6 and iNOS-deficient) were administered cerulein by intraperitoneal (i.p.) injection at hourly intervals for 7 hours and killed 24 hours later after the first dose. Pancreatic wet weight, pancreatic myeloperoxidase (MPO) activity, and levels of plasma nitrite and serum amylase were measured. In another experiment isosorbide dinitrate (an NO donor) was given by oral gavage every 6 hours for 24 hours beginning simultaneously with cerulein injections in iNOS-deficient mice. Cerulein administration dose-dependently increased pancreatic wet weight, myeloperoxidase activity, and levels of nitrite and amylase in C57B1/6 mice. These parameters (except nitrite levels) were significantly intensified in iNOS-deficient mice. At the dose employed, cerulein failed to increase nitrite levels in iNOS-deficient mice. The susceptibility to cerulein toxicity in iNOS-deficient mice was abolished by NO donor treatment. NO release from an iNOS source appears to play a protective role in cerulein-induced pancreatitis. At least in part, NO may prevent neutrophil accumulation after cerulein administration.

Therapeutic potential of endothelin receptor antagonists and nitric oxide donors in pulmonary hypertension

Pulmonary hypertension can occur idiopathically as a primary disorder of the pulmonary circulation or more commonly, it can exist as a haemodynamic manifestation of a wide variety of pulmonary and cardiovascular diseases, including acute lung injury, chronic obstructive lung disease, congenital heart disease, mitral stenosis, chronic left-sided congestive heart failure and connective tissue diseases such as scleroderma. Pulmonary hypertension is associated with changes in vascular tone as well as vascular structure, with the relative contribution of each dependent upon the aetiology of the increased pulmonary vascular resistance. Most currently available treatments utilise anticoagulants as well as vasodilator drugs that only attenuate the vasoconstrictive component of the disease. The latter category includes oral calcium channel blockers, iv. and aerosolised prostacyclin analogues and inhaled nitric oxide but all three classes of vasodilators have disadvantages and limitations. Treatment with vasodilators is often ineffective in patients with longstanding pulmonary hypertension in which structural changes contribute significantly to the pulmonary hypertension, blood flow obstruction and right heart failure. In view of the immense clinical need, new therapies are being developed by pharmaceutical companies to treat pulmonary hypertension. This update will focus on the current development status of endothelin receptor antagonists and nitric oxide donors for the treatment of pulmonary hypertension.

Therapeutic implications of human endothelial nitric oxide synthase gene polymorphism

Vascular endothelial dysfunction is now recognized as a common phenomenon in an array of cardiovascular disorders. Production of nitric oxide via the endothelial isoform of nitric oxide synthase [eNOS (previously termed NOS3 or ecNOS)] is vital for a healthy endothelium; several polymorphic variations of the gene encoding eNOS (NOS3) are now known and have been investigated with respect to disease risk. Surprisingly, only approximately half of these studies have demonstrated significant associations between NOS3 polymorphisms and cardiovascular disease, and many reports are contradictory. Central issues include adequate statistical power, appropriateness of control cohorts, multigene interactions and plausible biological consequences. So far, the inconsistencies are not unique to the NOS3 polymorphisms, but probably represent the broad challenges in defining genetic aspects of complex disease processes.

Comparative Trial of Local Pharmacotherapy withl-Arginine, r-Hirudin, and Molsidomine to Reduce Restenosis after Balloon Angioplasty of Stenotic Rabbit Iliac Arteries

PURPOSE

To determine if local application of L-arginine, r-hirudin, or molsidomine significantly reduces restenosis after balloon angioplasty in stenotic rabbit iliac arteries.

MATERIALS AND METHODS

Thirty-one male cholesterol-fed New Zealand white rabbits underwent balloon dilation of both common iliac arteries to induce arterial stenosis. Four weeks later, one stenotic iliac artery was simultaneously dilated and received local application of L-arginine (210 mg/mL, n = 7), r-hirudin (0.5 mg/mL, n = 8), or molsidomine (0.2 mg/mL, n = 8) with a channeled balloon catheter. On the contralateral side, 0.9% saline was injected as a control. In eight sham animals, saline was applied to one iliac artery and balloon dilation to only the contralateral artery. Six weeks after local treatment, vessels were harvested, and computerized morphometric and immunohistologic analyses were performed.

RESULTS

Application of drugs resulted in a significant reduction of neointimal area as follows: 53% with L-arginine (1.01 mm(2) vs. 2.17 mm(2), P <.05), 43% with molsidomine (1.04 mm(2) vs. 1.89 mm(2), P <.05), and 20% with r-hirudin (1.79 mm(2) vs. 2.24 mm(2), P <.05). Infusion of saline led to a significant increase (50%, 1.21 mm(2) vs. 1.93 mm(2), P <.05) in neointimal area compared with balloon dilation alone. Immunohistologic findings showed a significant reduction of macrophages (5.0% vs. 10.2%, P <.05) and proliferating cells (6.2% vs. 10.6%, P <.05) in the neointima after local application of L-arginine.

CONCLUSION

Reduction of neointimal area was significant for L-arginine and molsidomine but not for r-hirudin. Saline infusion caused significant arterial trauma, resulting in additional neointimal proliferation.

[Role of nitric oxide in heart failure]

The benefit effects of nitric oxide (NO) donors in acute heart failure have led to the development of vasodilators as treatment of chronic heart failure. However, the mechanisms involved in the effects of NO are complex and still discussed. In chronic heart failure, the eNOS downregulation in vascular endothelium explains the alteration of endothelial function. In addition, in the myocardium, cytokines induce the expression of inducible nitric oxide synthase (iNOS) which increase NO production by myocytes and surrounding cells. This excess of NO production, associated with anion superoxide synthesis, limits the inotropic properties of catecholamines and exert proapoptotic effects. The role of NO donors in heart failure treatment is still controversial but by reducing preload they improve patient's symptoms. Beside blockade of the renin-angiotensin system, the angiotensin converting enzyme inhibitors act via the inhibition of bradykinin degradation which increase NO levels. Finally, vascular endothelial NO expression is improved by exercise training and participates in the improvement of exercise capacity in patients with chronic heart failure involved in cardiac readaptation program.

Nitric oxide for treatment of threatened preterm labor

OBJECTIVE

The aim of our study was the assessment of effectiveness of nitroglycerin as a donor of nitric oxide, administered in the form of transdermal therapeutic system, applied in the treatment of threatening preterm labor.

PATIENTS AND METHODS

The study was carried out on 30 pregnant patients with the symptoms of threatening preterm labor between 27th and 34th week of gestation. The patients were given nitroglycerin in the form of transdermal system releasing 5 mg of nitroglycerin in 24 h.

RESULTS

In our study the decrease in contractility and relaxation of uterus was observed in all obstetric patients. No changes in the fetal pulse rate and cardiotocographic tracing in the course of treatment and after completing treatment were observed.

CONCLUSION

Nitroglycerin in the form of transdermal therapeutic system releasing nitric oxide may be an effective and safe tocolytic drug, however, further investigation needs to be performed.

SIN-1, a nitric oxide donor, ameliorates experimental allergic encephalomyelitis in Lewis rats in the incipient phase: the importance of the time window

NO is involved in the regulation of immune responses. The role of NO in the pathogenesis of experimental allergic encephalomyelitis (EAE) is controversial. In this study, 3-morpholinosydnonimine (SIN-1), an NO donor, was administered to Lewis rats on days 5-7 postimmunization, i.e., during the incipient phase of EAE. SIN-1 reduced clinical signs of EAE compared with those in PBS-treated control rats and was accompanied by reduced ED1(+) macrophages and CD4(+) T cell infiltration within the CNS. Blood mononuclear cells (MNC) obtained on day 14 postimmunization revealed that SIN-1 administration enhanced NO and IFN-gamma production by blood MNC and suppressed Ag- and mitogen-induced proliferative responses. MHC class II, B7-1 and B7-2 were down-regulated in SIN-1-treated EAE rats. Simultaneously, frequencies of apoptotic cells among blood MNC were increased. In vivo, SIN-1 is likely to behave as an NO donor. Administration of SIN-1 induced NO production, but did not affect superoxide and peroxynitrite formation. Enhanced NO production during the priming phase of EAE thus promotes apoptosis, down-regulates disease-promoting immune reactivities, and ameliorates clinical EAE, mainly through SIN-1-derived NO, without depending on NO synthase.

Tacrolimus in acute renal failure: does L-arginine-infusion prevent changes in renal hemodynamics?

Nephrotoxicity is one of the main side effects of calcineurin-inhibitors. The influence of tacrolimus on the renal vasculature has not been well described. We have therefore examined the effects of tacrolimus on renal functional parameters as well as the contribution of the NO-system in a model of ischemic acute renal failure (ARF). Induction of ARF was achieved by clamping both renal arteries of female Sprague-Dawley rats. During the experiment, RBF, GFR, MAP, RVR and FENa were determined during infusion of vehicle, TAC, TAC and the NOS-activator L-arginine, and TAC and NOS-inhibition due to L-NMMA. TAC induced a significant rise in RVR with further decrease of RBF and GFR. Simultaneous L-arginine-infusion could reverse these effects during the infusion without complete restoration to preischemic levels. NOS-inhibition increased MAP and RBF without any effect on GFR. FENa did not differ significantly between the groups. Tacrolimus in the situation of ischemic acute renal failure causes vasoconstriction of pre- and postglomerular vessels with a further deterioration of renal function. L-arginine abolishes the functional deterioration, most likely due to increased NO-liberation.

Divergent effects of ischemia/reperfusion and nitric oxide donor on TNFalpha mRNA accumulation in rat organs

We previously showed that serum TNFalpha bioactivity in rats is proportional to the extent of graded tissue injury caused by laparotomy, intestinal ischemia, and reperfusion and that the spleen is an important source of TNFalpha secretion in this condition. TNFalpha production varies, depending on the type and duration of tissue injury. It is also affected by other mediators, such as nitric oxide (NO). TNFalpha is known to increase NO production, but the effect of NO on the production of TNFalpha has not yet been fully elucidated. In this study we determined the levels of TNFalpha mRNA in rat organs after graded injury caused by anesthesia, laparotomy, intestinal ischemia, and reperfusion and evaluated the effects of the NO donor S-nitroso-N-acetylpenicillamine (SNAP) on it. Samples from different organs were removed, and TNFalpha gene expression was evaluated by semiquantitative RT-PCR. TNFalpha mRNA was not detected in the intestine (the ischemic organ) and in the kidney, brain, heart, or liver after all 4 experimental protocols. In the mesenteric lymph node (draining the ischemic organ) a basal level of expression of TNFalpha mRNA was detected in the control (anesthesia alone) group, which was increased significantly after ischemia. In the spleen (a remote immune organ not directly involved in the ischemia), a significant gradual increase in TNFalpha mRNA, which correlated to the severity of the experimental protocol, was observed. In the lung (a central participant in post-injury multiple organ failure), all interventions increased TNFalpha mRNA. Infusion of SNAP exerted a differential effect on TNFalpha mRNA: diminished its accumulation in the lymph node, enhanced it in the lung, and had no effect in the spleen. The divergent organ pattern of TNFalpha transcription emphasizes the importance of its localized expression, which is critical to the understanding of its autocrine and paracrine actions in ischemia and reperfusion.

Pharmacological treatment of severe hypertension in pregnancy and the role of serotonin(2)-receptor blockers

Hypertensive disorders of pregnancy are the leading cause of maternal and perinatal mortality and morbidity in developing and developed countries. The etiology of preeclampsia is still unknown. Delivering the baby is the only definite treatment. The benefits of acute pharmacological control of severe hypertension prior to and/or post-delivery are generally accepted. Most drugs commonly used in the management of severe hypertension in pregnancy have significant maternal and/or neonatal adverse side effects. Furthermore, some are not effective to acutely lower the blood pressure in patients with a hypertensive crisis. Until recently not one of the commonly used antihypertensive drugs has been tailored to the pathophysiology of severe preeclampsia, being a clinical syndrome characterized by endothelial cell dysfunction, vasospasm and platelet aggregation. Ketanserin, a serotonin(2)-receptor blocker, is a drug that appears to be tailored for treating this pregnancy-associated enthothelial cell dysfunction. The results of several prospective trials show that there is a definite place for serotonin(2)-receptor blockers in the treatment of pregnancy-induced hypertensive disorders. This review provides a summary on the more established drugs as well as on some of the newer antihypertensive drugs used in pregnancy with emphasis on the existing experience with ketanserin.

[Drug treatment of erection disorders in patients with cardiovascular disease]

Erectile dysfunction is a frequent condition in cardiovascular patients. Since the arrival of oral erection-supporting medication, patients want to know how safe sexual activity is in cardiovascular disease in general and during use of erection-supporting medication in particular. Sexual intercourse with a steady partner causes no more cardiovascular risk than normal daily activities such as ironing, 2 kilometers of walking without climbing, paperhanging, playing golf or gardening. The relative risk of myocardial infarction during sexual activity is not significantly higher than for healthy persons. The incidence of cardiovascular morbidity and mortality is not higher among users of sildenafil. Sildenafil is contraindicated in patients using long-acting nitrates or who may need to use short-acting nitrates, because the combination may cause a sharp fall of the blood pressure. No interactions have been observed with beta-receptor blockers, calcium antagonists, thiazide and loop diuretics and ACE inhibitors. Before prescribing a symptomatic (pharmaceutical) treatment for patients with an erection disorder, attention should be given tot the sexological, psychological and medical backgrounds of the disorder. Secondary prevention of atherosclerotic risk factors is also important: regulation of blood pressure and blood sugar level, hyperlipidaemia and obesity, as well as a change of lifestyle (giving up smoking, adapting of diet and more physical exertion). Patients with a very low cardiac capacity should be advised to refrain from treatment of the erection disorder.

Role of nitric oxide in gastrointestinal inflammatory and ulcerative diseases: perspective for drugs development

Nitric oxide is a ubiquitous molecule involved in a variety of biological processes. The specific action of NO depends on its enzymatic sources namely neuronal nitric oxide synthase (nNOS), endothelial NOS (eNOS) and inducible NOS (iNOS) and all three isoforms have been localized in the gastrointestinal tract. Constitutive synthesis of NO by nNOS or eNOS isoforms is involved in the maintaining of the gastrointestinal mucosal integrity through modulation of gastric mucosal blood flow, epithelial secretion and barrier function. However, large amounts of NO synthesized from the inducible isoform have been implicated in tissue injury in the gut during inflammatory reactions. In this review we provide an overview of the dual role of nitric oxide in modulating gastrointestinal mucosal defense and injury. In addition, we highlight the therapeutic potential of NO modulation.

Effect of systemically administered nitric oxide donor, sodium nitroprusside on picrotoxin-induced convulsions in rats

Nitric oxide (NO), the gaseous neurotransmitter has been reported to have an endogenous anticonvulsant property. This has prompted proposals to develop NO donors as anticonvulsant drugs. In the present study, the effect of NO donor, sodium nitroprusside (SNP) on picrotoxin (PCT)-induced convulsions was investigated. A convulsant dose of PCT (5 mg/kg) was administered 5, 10, 15 and 30 min after intraperitoneal injection of graded doses (0.7, 1.25 and 2.5 mg/kg) of SNP. SNP at doses 0.7 and 1.25 mg/kg increased dose dependently the severity of PCT-induced convulsions. But, pretreatment with the higher dose (2.5 mg/kg) of SNP was protective against PCT-induced convulsions. However, post treatment (5 and 10 min) with the same dose exacerbated convulsions and caused death of the animals. These results indicate that the vasodilator effect of SNP and an increased perfusion of PCT into brain may be responsible for the proconvulsant action of SNP. A decreased entry of PCT because of marked vasodilation and hypotension has been speculated for an inhibition of convulsions in animals pretreated with a higher dose of SNP. In conclusion, the results reveal the non-suitability of SNP to be developed as an anticonvulsant.

Independent determinants of the efficacy of nitrate therapy

BACKGROUND

Asymmetric dosage regimens of isosorbide mononitrate provide better antianginal efficacy and quality of life in patients with stable angina pectoris than the daily administration of multiple small doses of the compound. It is not known whether certain patient characteristics contribute to this improved benefit.

OBJECTIVE

To determine independent factors contributing to this improved benefit. Multiple linear regression analysis was performed with a self assessment study in 1350 patients with stable angina pectoris. Quality of life was assessed by the Marquis questionnaire for patients with angina and included the assessment of immobility, pain and psychological distress. Individual scores were calculated as the pooled sums of the assessment scores and were expressed on an ordinal scale of 10.

RESULTS

Age did not influence the improvement in benefit. Gender, rhythmic disturbances, peripheral artery disease and the concomitant use of calcium channel blockers or beta-blockers were without effect. New York Heart Association angina classification was an independent variable: patients with a class I or II showed less benefit than did patients with class III or IV (p = 0.02). Obese patients as well as hypertensive patients (p = 0.04 and 0.02), and smokers also tended to benefit less (p = 0.08). In contrast, the presence of cholesterolemia and diabetes mellitus were associated with increase in the beneficial effect of nitrates on quality of life (p = 0.03 and 0.05).

CONCLUSIONS

Patients with severe angina pectoris benefit better from nitrate therapy than do patients with New York Heart Association class I - II. Also, patients with coronary artery disease and concomitant diabetes mellitus or cholesterolemia may benefit better from nitric oxide donor therapy than patients without such condition. In contrast, patients with concomitant obesity, hypertension, or who are smokers may show less benefit.

[The effect of exogenous nitric oxide on endothelial dysfunction in two-kidney, one-clip renovascular hypertensive rats]

Previous studies have shown that hypertension causes endothelial dysfunction. To study the influence of exogenous nitric oxide(NO) on endothelial dysfunction produced by hypertension, we administered a non-depressor dose of nipradilol to two-kidney, one-clip renovascular hypertensive rats(2K1C). Sprague-Dawley rats underwent either sham surgery(G-1) or clipping of the left renal artery. From day seven, 2K1C were randomized into 3 groups, placebo treatment(G-2), nipradilol treatment(G-3,) and propranolol treatment(G-4). Urinary NO2- + NO3-(NOx) excretion (UNOx V) was measured 4 weeks after clipping, and then, acetylcholine(Ach), A23187, or sodium nitroprusside(SNP)-induced relaxation were measured in the aorta. Blood pressure was increased in G-2, G-3, and G-4 compared to G-1. UNOx V was lower in G-2, G-3, and G-4 compared to G-1, but UNOx V was higher in G-3 compared to G-2 and G-4. Although Ach or A23187-induced relaxation was significantly decreased in isolated artery from G-2, G-3, and G-4 compared with those from G-1. Ach- or A23187-induced relaxation was improved in G-3. SNP-induced relaxation did not differ among the 4 groups. These results suggest that exogenous NO from nipradilol reduces the endothelial dysfunction caused by hypertension without changing the blood pressure.

Nonsteroidal anti-inflammatory drugs

NSAID-associated dyspeptic symptoms are common and can be managed empirically with an H2-receptor antagonist or a proton-pump inhibitor. Treatment of established gastroduodenal ulcers is accomplished best by withholding the offending drugs. Proton-pump inhibitors appear to heal ulcers at the same rate whether or not NSAID therapy is continued. After the ulcer is healed and if NSAID therapy must be continued, prophylaxis is accomplished best by the concomitant use of proton-pump inhibitors, misoprostol (at least 200 micrograms 3 times a day), or a NSAID that preferentially inhibits COX-2. The future development of newer, safer NSAID preparations, including highly selective COX-2 inhibitors and nitric oxide-releasing NSAIDs, should provide better treatment options for the increasing number of individuals requiring anti-inflammatory agents.

Pharmacology of selectin inhibitors in ischemia/reperfusion states

Recently, the selectin family of glycoprotein adhesion molecules (P-selectin, E-selectin, and L-selectin) has been implicated in the pathogenesis of a number of inflammatory disease states. The selectins modulate the early adhesive interactions between circulating neutrophils and the endothelium. Both P-selectin and E-selectin can be expressed on the surface of endothelial cells following stimulation by a number of inflammatory mediators. In contrast, L-selectin is constitutively expressed on the surface of neutrophils at very high levels. In addition, neutrophils also express ligands for the endothelial selectins, including the carbohydrate sialyl Lewis(x) and the high-affinity ligand P-selectin glycoprotein ligand 1, which facilitate neutrophil-endothelial interactions. Selectins have been extensively investigated in ischemia/reperfusion injury states. The study of selectin involvement in ischemia/reperfusion injury has been facilitated by the development of highly specific selectin antagonists, including monoclonal antibodies, carbohydrates, small molecule inhibitors, and soluble forms of P-selectin glycoprotein ligand 1. This article reviews the results of current studies of selectin antagonists in experimental models of ischemia/reperfusion injury.

Clinical experience of long-term transdermal treatment with nitric oxide donor for women with preeclampsia

Isosorbide dinitrate (ISDN), a nitric oxide donor, was applied transdermally for 4-16 days to 4 preeclamptic women with oligohydramnios, intrauterine fetal growth retardation (IUGR), and elevated resistance of blood flow in the uterine arteries. Pulsed Doppler ultrasonography revealed immediate and drastic improvement of pulsatility index (PI) of uterine arteries following treatment with ISDN. The average PI in uterine arteries of the 4 patients was reduced to approximately 67% of that of the untreated state. In 2 patients the amniotic fluid gradually increased over a few days which suggested improvement of fetoplacental circulation during administration of ISDN. This study suggests that long-term transdermal ISDN is an effective therapy, at least in a portion of preeclamptic women, to avoid maternal hypertension, fetal distress, oligohydramnios, and IUGR, and consequentially to prolong the gestational period.

Impact of polynitroxylated albumin (PNA) and tempol on ischemia/reperfusion injury: intravital microscopic study in the dorsal skinfold chamber of the Syrian golden hamster

Nitric oxide-releasing drugs have been shown to reduce ischemia/reperfusion (I/R) injury by acting as radical scavengers. However, their therapeutic application is hampered by specific side effects and rapid bioreduction in vivo. The half-life and antioxidant activity of nitroxides may be enhanced by their covalent binding to human serum albumin, resulting in polynitroxyl albumin (PNA). Thus, PNA may represent a novel antioxidative drug. The objectives of this study were to elucidate 1) whether PNA is able to diminish I/R injury; 2) the most effective dose of PNA in vivo; and 3) whether the addition of the nitroxide tempol enhances and/or prolongs the effect of PNA. Experiments were performed using a 4-h tourniquet-induced ischemia model in the hamster dorsal skinfold chamber. In the first part, five groups (n = 6) of animals received an infusion of 1) 1% body weight (b.w.) saline (0.9%); 2) 0.5% b.w. albumin (20%); 3) 0.5% b.w. PNA (20%); 4) 1% b.w. albumin (20%); and 5) 1% b.w. PNA (20%) 15 min prior to reperfusion. In the second part of the study, tempol (17 mg/mL) was added either to albumin or PNA (1:9), and 0.5% b.w. of this solution was infused (Group 6: tempol + albumin 0.5% b.w.; Group 7: tempol + PNA 0.5% b.w.). Intravital fluorescence microscopy allowed for quantification of functional capillary density (FCD), leukocyte adherence, extravasation of fluorescein isothiocyanate-labeled Dextran and non-viable (Propidium-positive) cell count prior to ischemia and 0.5 h, 2 h, and 24 h after reperfusion. PNA and--to a lesser extent albumin--effectively reduced postischemic microvascular perfusion failure, leukocyte adhesion, and tissue injury. PNA was most effective in the dose 1% b.w. Although free oxygen radical scavenging seems to be an underlying mechanism leading to the beneficial effects of PNA on I/R injury, hemodilution and known radical scavenging properties of pure albumin contribute in part to the observed effects. Although the combination of tempol and PNA revealed further short-term effects on microvascular perfusion and leukocyte adhesion, it did not result in a long-term improvement of tissue injury.

Effects of angiotensin II blockade on nitric oxide blood levels in IgA nephropathy

BACKGROUND

The effects of renin-angiotensin system blockade on nitric oxide (NO), especially in pathological conditions, are far from being established. The influence of kinins and angiotensin type 2 receptor are largely speculative and based mainly on animal studies. This study was aimed to address these aspects in humans.

METHODS

Eight IgA nephropathy patients with documented clinical and histological indicators of poor prognosis were given 50 mg of losartan, 10 mg of enalapril, and 40 mg of the NO donor isosorbide 5 mononitrate (as a control of NO generation) in randomized order for 7 days each. Treatment periods were separated by washout periods of 7 days each. Laboratory investigations were performed before and after each study period. Seven healthy controls received losartan and enalapril according to the same study design.

RESULTS

Glomerular filtration rate remained stable while effective renal plasma flow increased with each treatment (P<0.05). Under losartan and enalapril, filtration fraction fell (P=0.02), plasma renin activity increased (P<0.05) and urinary aldosterone concentration decreased (P=0.02). Angiotensin-converting enzyme activity was reduced to the limit of detection under enalapril (P<0.001). Blood NO, detected as nitrosylhaemoglobin by a recently developed technique of spin-trap electron paramagnetic resonance, increased significantly, as expected, during treatment with isosorbide 5 mononitrate (P=0.01), with enalapril (P<0.05), and also with losartan (P<0.05). Unlike losartan, enalapril significantly reduced albuminuria (P=0.01) in this short-term period. In the seven healthy controls, neither enalapril nor losartan were able to increase blood NO levels significantly.

CONCLUSIONS

Blood levels of nitrosylhaemoglobin, a surrogate marker of NO, increased under blockade of the renin-angiotensin system in patients with IgA nephropathy, but not in healthy volunteers. This increase could contribute to changes of effective renal plasma flow in renal disease states.

Sildenafil citrate potentiates the hypotensive effects of nitric oxide donor drugs in male patients with stable angina

OBJECTIVE

We sought to study the effects of a single oral dose of sildenafil citrate (50 mg) on blood pressure (BP) in men taking the nitric oxide (NO) donor drugs isosorbide mononitrate (ISMN) or glyceryl trinitrate (GTN) for stable angina.

BACKGROUND

Sildenafil, a selective phosphodiesterase type 5 inhibitor, is an orally effective treatment for erectile dysfunction. The presence of phosphodiesterases in the vasculature suggests the possibility of an interaction between sildenafil and NO donor drugs.

METHODS

Two double-blind, placebo-controlled, randomized, two-way crossover trials were undertaken. Sixteen male patients received oral ISMN (20 mg twice a day) for five to seven days before their dose of sildenafil or placebo and continued receiving ISMN daily until administration of the alternate drug seven days later. For the second study, 15 male patients received sublingual GTN (500 microg) 1 h after sildenafil or placebo on each of two study days, which were seven days apart. Sitting or standing BP was measured before and for 6 h after the administration of the study drug.

RESULTS

The effects of sildenafil plus ISMN on BP (standing mean maximum reductions from baseline in systolic/diastolic BP, -52/-29 mm Hg) were greater than the effects of placebo plus ISMN on BP (-25/-15 mm Hg; p < 0.001). Sildenafil plus GTN also resulted in greater sitting mean maximum reductions from baseline in systolic/diastolic BP (-36/-21 mm Hg) compared with placebo plus GTN (-26/-12 mm Hg; p < 0.01).

CONCLUSIONS

Coadministration of sildenafil with ISMN or GTN produced significantly greater reductions in BP than ISMN or GTN alone. Based on these data, sildenafil should not be administered to patients taking nitrates.

Reduction of infarct size by the NO donors sodium nitroprusside and spermine/NO after transient focal cerebral ischemia in rats

Nitric oxide (NO) plays a dual role (neuroprotection and neurotoxicity) in cerebral ischemia. NO promoting strategies may be beneficial shortly after ischemia. Therefore, we have studied the hemodynamic and possible neuroprotective effects of two NO donors, the classical nitrovasodilator sodium nitroprusside (SNP) and the NONOate spermine/NO, after transient focal cerebral ischemia in rats. Parietal cortical perfusion was measured by laser-Doppler flowmetry. The effects of increasing intravenous doses (10-300 microgram) of sodium nitroprusside and spermine/NO on cortical perfusion and arterial blood pressure were assessed. Transient (2 h) focal cerebral ischemia was carried out by the intraluminal thread method. The effects of intraischemic intravenous infusion of SNP (0.11, 1.1 mg/kg) and spermine/NO (0.36, 3.6 mg/kg) on hemodynamic parameters and infarct size developed after 1 week reperfusion were assessed. In control conditions, SNP and, to a lesser extent, spermine/NO induced dose-dependent hypotension and concomitant reduction in cortical perfusion. In focal cerebral ischemia, infusion of SNP (0.11 mg/kg) and spermine/NO (0.36, 3.6 mg/kg) reduced the infarct size. In the case of spermine/NO, cortical perfusion was maintained above the control levels during the ischemic insult. No significant hypotension was elicited by NO donors at the dose-ratios infused. In conclusion, brain damage induced by transient focal ischemia is reduced by intravenous NO donors. Neuroprotective effects of spermine/NO are due at least in part to improvement of brain perfusion, while sodium nitroprusside must provide direct cytoprotection. These results give further support to the protective effect of NO in the early stages of cerebral ischemia and point to the therapeutic potential of NONOates in the management of brain ischemic damage.

Pharmacotherapy for erectile dysfunction

OBJECTIVE

To review current pharmacologic treatment options for erectile dysfunction.

METHODS

Relevant literatures from the past two decades regarding the following treatments were reviewed: intracavemous injection, topical therapy, transurethral therapy and oral drugs.

STUDY SELECTION

More than 125 originally identified articles were reviewed, and 45 were selected that especially addressed the stated purpose.

RESULTS

Among the pharmacologic treatment options available, intracavemous injection therapy remains the most effective although the drop-out rate is high. Topical creams and gels have not been very successful. Transurethral alprostadil can be more effective if a constriction device is applied at the base of the penis. Oral sildenafil has the highest patient acceptance rate although systemic side effects can be a major drawback.

CONCLUSIONS

Effective pharmacotherapies for ED of various etiologies are now available. However, proper evaluation of every patient should be performed before giving treatment so that a number of potentially life-threatening causes of erectile dysfunction would not be missed.

The effects of FK409 on pulmonary ischemia-reperfusion injury in dogs

FK409 is the first spontaneous nitric oxide (NO) donor known to increase plasma cyclic guanosine 3',5'monophosphate levels. In this study, we evaluated the effect of FK409 on pulmonary ischemia-reperfusion injury in an in situ warm ischemia canine model. Fourteen dogs were divided into two groups, and the FK409-treated group was given 5 micrograms/kg per min FK409. Warm ischemia was induced for 3 h. The arterial partial pressure of oxygen (PaO2), arterial oxygen saturation (SaO2), cardiac output (CO), left pulmonary vascular resistance (L-PVR), and endothelin-I (ET-I) were measured. A histologic study was performed, and polymorphonuclear neutrophils (PMNs) were also counted. The PaO2, SaO2, and L-PVR levels and PMNs after 30 min of reperfusion, ET-I after 2 h of reperfusion, and the 7-day survival rate were significantly (P < 0.05) better in the FK409-treated group than in the control group. The histologic damage was reduced in the FK409-treated group compared to the control group. FK409 appears to have a protective effect in ischemia-reperfusion injury of the lung.

The sixth Carlos E. Rubio Memorial Lecture. Prevention and treatment of variceal hemorrhage

The medical treatment of portal hypertension has experienced a marked progress in the past decade due to the introduction of effective portal hypotensive therapy. This has been possible because of the better understanding of the pathophysiological mechanisms leading to portal hypertension. A major step forward was the introduction of beta-blockers for the prevention of bleeding and rebleeding from gastroesophageal varices. Effective therapy requires the reduction of the hepatic venous pressure gradient (HVPG) to 12 mmHg or below, or at least by 20% of baseline values. Unfortunately, this is only achieved in 1/3 to 1/2 of patients. Combination therapy, associating isosorbide-5-mononitrate and propranolol or nadolol administration enhances the reduction in portal pressure and increases the number of patients in whom HVPG decreases by more than 20% of baseline values and below 12 mmHg. Randomized clinical trials (RCT's) do support the concept that combination therapy is more effective than propranolol or nadolol alone, significantly better than sclerotherapy, and probably than endoscopic banding ligation. Therapy may be complemented by the association of spironolactone. The main inconvenience of pharmacological therapy is that there is no non-invasive method available to detect non-responders to treatment. Failures of drug therapy should be managed endoscopically. Failures of endoscopic treatment require 'rescue' by means of TIPS or shunt surgery. Patients with advanced liver failure should be considered for orthotopic liver transplantation, and put into a waiting list if eligible. In the treatment of acute variceal bleeding pharmacological therapy offer the unique advantage of allowing to provide specific therapy immediately after arrival to hospital, or even during transferral to hospital by ambulance, since it does not require sophisticated equipment and highly qualified medical staff. Vasopressin has been abandoned because of its toxicity, although this can be reduced by the combined administration of transdermal nitroglycerin. Terlipressin has longer effects and is more effective and safer than vasopressin alone or in combination with nitroglycerin. It has proved to be effective and to decrease mortality from bleeding in double-blind studies. RCT's have shown that this drug is as effective and safer than emergency sclerotherapy. Therapy should be maintained for five days to prevent early rebleeding. Somatostatin is probably as effective as terlipressin. Octreotide is probably useful after endoscopic therapy but can not be recommended as first line treatment. Endoscopic injection sclerotherapy and endoscopic banding ligation are very effective, but require well trained medical staff. There is an increasing trend for initiating therapy with a pharmacological agent, followed by semi-emergency endoscopic therapy as soon as a well trained endoscopist is available (within 12-24 hours), while maintaining drug therapy for 5 days. Failures of medical therapy may be treated by a second session of endoscopic treatment, but if this fails TIPS of emergency surgery should be done. In high-risk situations, such as bleeding from gastric varices or in patients with advanced liver failure, the decision for TIPS or surgery should be done earlier, after failure of the initial treatment.

Attenuation of intestinal ischemia/reperfusion injury with sodium nitroprusside: studies on mitochondrial function and lipid changes

Reactive oxygen species have been implicated in cellular injury during ischemia/reperfusion (I/R). Mitochondria are one of the main targets of oxygen free radicals and damage to this organelle leads to cell death. Reports suggest that nitric oxide (NO) may offer protection from damage during I/R. This study has looked at the functional changes and lipid alteration to mitochondria during intestinal I/R and the protection offered by NO. It was observed that I/R of the intestine is associated with functional alterations in the mitochondria as suggested by MTT reduction, respiratory control ratio and mitochondrial swelling. Mitochondrial lipid changes suggestive of activation of phospholipase A(2) and phospholipase D were also seen after (I/R) mediated injury. These changes were prevented by the simultaneous presence of a NO donor in the lumen of the intestine. These studies have suggested that structural and functional alterations of mitochondria are prominent features of I/R injury to the intestine which can be ameliorated by NO.

S-Nitroso-N-acetylpenicillamine (SNAP) during hemorrhagic shock improves mortality as a result of recovery from vascular hyporeactivity

Nitric oxide donors are protective against hemorrhagic shock (HS). However, no detailed investigation has been performed. We investigated this mechanism using S-nitroso-N-acetylpenicillamine (SNAP). HS (mean arterial pressure: 40 mm Hg) was induced in 20 dogs. Sixty min after HS, the animals were treated with saline (Cont-Gr: n = 7) or SNAP; 5 microg. kg(-1). 10 min(-1) followed by 5 microg. kg(-1). h(-1) (SNAP-Gr: n = 7). After another 60 min, the shed blood was reinfused. Reactivities to noradrenalin (NA), changes in hemodynamics, the plasma catecholamines, and nitric oxide derivatives were determined. In Cont-Gr, 3 dogs died at 90, 98, and 102 min after HS. In Cont-Gr, % changes of systolic arterial blood pressure to 1 and 2.5 microg/kg of NA after the recovery from HS decreased from 23.7% +/- 4.1% (before HS) to 6.5% +/- 0.6% and from 50.1% +/- 7.7% (before HS) to 14.5% +/- 2.6%, respectively (P < 0. 01). In SNAP-Gr, reactivity to NA was maintained. At 120 min after HS, mean arterial pressure and cardiac output in SNAP-Gr increased but not in Cont-Gr. Plasma catecholamine levels in SNAP-Gr were suppressed compared with those of Cont-Gr. In conclusion, a small dose of SNAP during HS decreased the mortality of the dogs. This might have been caused in part by residual vascular hyporeactivity.

IMPLICATIONS

The administration of a small dose of S-nitroso-N-acetylpenicillamine (a nitric oxide donor), a dose which did not exert a significant vasodilator effect, was administered during hemorrhagic shock in dogs. S-nitroso-N-acetylpenicillamine improved the vascular hyporeactivity to noradrenaline and decreased the mortality rate.

Beneficial effects of novel nitric oxide donor (FK409) on pulmonary ischemia-reperfusion injury in rats

BACKGROUND

Nitric oxide (NO) seems to play an important role in tissue injury during reperfusion of the lung. FK409 is the first spontaneous NO donor that increases plasma guanosine 3':5'-cyclic monophosphate. It is reported that FK409 prevented myocardial infarction following occlusion and reperfusion in rat coronary arteries. In this study, we evaluated the effects of FK409 on pulmonary ischemia-reperfusion injury in an in situ warm ischemia model of rats.

METHODS

Animals were divided into 2 groups: the FK409 study group that was administered FK409 (0.4 mg/kg) before reperfusion and the control group, administered a saline vehicle only. Following a thoracotomy, the bronchus, pulmonary artery and vein were separately clamped for 1 hour. Arterial oxygen tension (PaO2), arterial oxygen saturation (SaO2), and endothelin-I (ET-I) were measured after 2 hours of reperfusion. Histologic and immunohistochemical studies were performed; polymorphonuclear neutrophils (PMNs) were counted after 2 hours of reperfusion.

RESULTS

PaO2, SaO2, ET-I after 2 hours of reperfusion and the 7-day survival rate were significantly (p < 0.05) better in the FK409 group than the control group. Histologic damage was reduced in the FK409 group compared with the control group. PMN infiltration was also significantly (p < 0.05) lower in the FK409 group than in the control group.

CONCLUSION

FK409 seems to protect against ischemia-reperfusion injury of the lung. This effect may be related to a homeostatic effect on pulmonary vascular beds and prevention of PMN sequestration.

Protective effect of the nitric oxide donor molsidomine on indomethacin and aspirin-induced gastric injury in rats

OBJECTIVE

To study the effect of the nitric oxide donor, molsidomine, on gastric and duodenal injury induced by indomethacin and aspirin.

METHODS

Sprague-Dawley rats weighing 180-200 g were used after 24 h fasting. Indomethacin (5 mg/kg) was given subcutaneously as a single dose and followed by multiple injections of histamine. Molsidomine (0.05 mg/kg) or distilled water was given by gavage 30 min before indomethacin and repeated at 3 h intervals for two doses. Rats were killed 2 h after the last dose of molsidomine. Aspirin (500 mg/kg) was given by gavage and repeated 2.5 h later. Molsidomine or distilled water was given 30 min before the initial aspirin dose and repeated after 2 h. Animals were killed 2.5 h after the second dose of aspirin. The severity of the gastric mucosal damage was graded from 0 to 3, and the duodenal bulb ulcer surface area calculated by two independent observers using a dissecting microscope.

RESULTS

Indomethacin and aspirin resulted in significant gastric mucosal damage with median scores of 2 (interquartile ranges 1.4-3, n = 16 and 2-3, n = 10, respectively). Molsidomine significantly ameliorated indomethacin- and aspirin-induced damage with median scores of 1 (interquartile ranges 0.5-1.5, n = 19 and 0.6-1.9, n = 10, respectively; P<0.008 and P<0.02, respectively (Mann-Whitney Utest)). Molsidomine had no effect on duodenal bulb ulcerations caused by indomethacin.

CONCLUSION

Oral molsidomine has a protective effect on gastric mucosa against damage induced by ulcerogenic agents. This could have an important clinical benefit, especially in cardiac patients taking aspirin in addition to a nitric oxide donor such as molsidomine.

Nitric oxide donors (nitrates), L-arginine, or nitric oxide synthase inhibitors for acute ischaemic stroke

BACKGROUND

Nitric oxide has several effects that may be beneficial in ischaemic stroke and useful in the management of hypertension in acute stroke. Some forms of nitric oxide synthase inhibition may also be beneficial. However, high concentrations of nitric oxide are likely to be toxic to brain tissue.

OBJECTIVES

The objective of this review was to assess the effects of nitric oxide donors, L-arginine, or nitric oxide synthase-inhibitors in people with acute ischaemic stroke.

SEARCH STRATEGY

We searched the Cochrane Stroke Group trials register (July 1997), Medline (for trials from 1965), Embase (from 1980) and ISI (from 1981). We contacted drug companies and researchers in the field.

SELECTION CRITERIA

Randomised and quasi-randomised trials comparing nitric oxide donors, L-arginine, or nitric oxide synthase-inhibitors in patients within one week of onset of confirmed ischaemic stroke.

DATA COLLECTION AND ANALYSIS

Two reviewers independently applied the inclusion criteria.

MAIN RESULTS

No completed trials were found. One small placebo-controlled trial of glyceryl trinitrate patches is underway.

REVIEWER'S CONCLUSIONS

There is currently no evidence from randomised trials on the effects of nitric oxide donors, L-arginine, or nitric oxide synthase-inhibitors in patients with acute ischaemic stroke.

Hydroxylamine attenuates the effects of simulated subarachnoid hemorrhage in the rat brain and improves neurological outcome

Some of the neurological deficits that emerge after aneurysmal subarachnoid hemorrhage (SAH) in humans are presumably caused by ischemic brain damage consequential to SAH-induced delayed cerebral vasospasm. This vasospasm probably results from an imbalance among vasoactive factors released from both the clot formed by extravasated blood and adjacent tissues, and in particular from a decrease in the endothelium-derived relaxing factor nitric oxide (NO). Brain ischemia is also known to elevate brain production and deposition of beta-amyloid, and to induce a delayed increase in total NO synthase (NOS) activity due to induction of expression of so-called induced NOS isoform, phenomena that may secondarily contribute to SAH-related brain damage. The aim of this study was to investigate the effects of treatment with the intracellular NO donor hydroxylamine on: (i) basilar arterial wall that remained in a direct contact with the clot, (ii) formation of the beta-amyloid precursor protein (beta-APP), (iii) total brain NOS activity, and (iv) neurological outcome in a 'two-hemorrhage' rat SAH model. Intraperitoneal (i.p.) administration of 0.18 mmol/kg hydroxylamine hydrochloride (12.5 mg/kg) twice daily for 7 days beginning immediately after the first 'hemorrhage' (intracisternal blood injection) reduced basilar arterial wall damage and attenuated post-SAH neurological deficit. It also reduced the SAH-related increases in hippocampal and cortical beta-APP immunoreactivities and hippocampal NOS activity measured 24 h after commencement of the treatment. These results indicate that intracellular NO donors that yield NO through the action of widely distributed enzymes in brain cells (cytochromes, catalase) can attenuate detrimental effects of SAH.

Molluscum contagiosum effectively treated with a topical acidified nitrite, nitric oxide liberating cream

A double-blind, group-sequential clinical trial of acidified nitrite was performed to demonstrate the efficacy of this nitric oxide donor in treating molluscum contagiosum. Subjects received either 5% sodium nitrite co-applied with 5% salicylic acid under occlusion, or identical cream with 5% salicylic acid, omitting sodium nitrite. Active and control treatment groups were well matched for the number and duration of lesions and made a similar number of applications. We found a 75% cure rate in the active treatment group and 21% cure with control treatment (P = 0.01). The mean time to cure was 1.83 months. Staining of the skin and irritation were frequent side-effects but did not prevent successful treatment.

[Role of endothelin and nitric oxide in early gut ischemia]

OBJECTIVE

Inadequate perfusion in splanchnic organs and especially in the gut during acute burn period has been reported in many conventionally "successfully" resuscitated patients, but the mechanisms still remain unclear and its early preventive measures need to be further studied. The aim of this study is to evaluate the role of endothelin and nitric oxide in gut ischemia.

METHODS

Eighteen male pigs were randomly assigned to one of the three groups: group C, a sham burn group that was subjected to all surgical procedures except burn; group B, sustained 30% TBSA cutaneous thermal burn; Group N, NO donor (C87-3754) was given intravenously (0.0125 mg.kg-1.min-1) at the beginning of resuscitation.

RESULTS

In group B, PVF decreased rapidly after burn, and did not recover in the observation period (72 h), ET levels in portal blood and intestinal tissue elevated contrary to the changes in NO. In group N, PVF was higher than in group B.

CONCLUSION

1. Changes in ET and NO may influence the protal blood flow. 2. NO donor was proved to be beneficial in improving GI tissue perfusion by releasing NO.