Mechanisms of action of nitrates

Isosorbide DiNitrate Effect on Hemodynamic Profile, Liver Stiffness, and Exercise Tolerance in Fontan Circulation (The NEET Clinical Trial)

After Fontan operation, decreased venous capacitance and venoconstriction are adaptive mechanisms to maintain venous return and cardiac output. The consequent higher venous pressure may adversely impact end-organ function, exercise capacity and result in worse clinical outcomes. This pilot study evaluated the safety and effect of isosorbide dinitrate (ISDN), a venodilator, on exercise capacity, peripheral venous pressure (PVP), and liver stiffness in patients with Fontan circulation. In this prospective single-arm trial, 15 individuals with Fontan circulation were evaluated at baseline and after 4 weeks of therapeutic treatment with ISDN. Primary aims were to assess the safety of ISDN and the effect on maximal exercise. We also aimed to evaluate the effect of ISDN on ultrasound-assessed liver stiffness, markers of submaximal exercise, and PVP at rest and peak exercise. Repeated measures t-tests were used to assess change in variables of interest in response to ISDN. Mean age was 23.5 ± 9.2 years (range 11.2-39.0 years), and 10/15 (67%) were male. There was no statistically significant change in peak VO2 (1401 ± 428 to 1428 ± 436 mL/min, p = 0.128), but VO2 at the anaerobic threshold increased (1087 ± 313 to 1115 ± 302 mL/min, p = 0.03). ISDN was also associated with a lower peak exercise PVP (22.5 ± 4.5 to 20.6 ± 3.0 mmHg, p = 0.015). Liver stiffness was lower with ISDN, though the difference was not statistically significant (2.3 ± 0.4 to 2.1 ± 0.5 m/s, p = 0.079). Of the patients completing the trial, mild headache was common (67%), but there were no major adverse events. Treatment with ISDN for 4 weeks is well-tolerated in patients with a Fontan circulation. ISDN is associated with an increase in VO2 at anaerobic threshold, lower peak PVP, and a trend toward lower liver stiffness. Larger, longer duration studies will be necessary to define the impact of ISDN on clinical outcomes in the Fontan circulation.Clinical Trial Registration: URL: https://clinicaltrials.gov . Unique identifier: NCT04297241.

Double-Masked, Vehicle-Controlled, Randomized, Phase II Study of the Ocular Hypotensive Activity and Safety of VVN539 Ophthalmic Solution

Purpose

To assess safety and ocular hypotensive efficacy of VVN539 ophthalmic solution in a first-in-human study.

Design

Multicenter, double-masked, randomized, vehicle-controlled, dose-response, parallel-comparison study.

Participants

Sixty-eight subjects with ocular hypertension (OHT) or open-angle glaucoma enrolled at 5 private practices.

Methods

After washout of ocular hypotensive medications as required, the subjects were randomized to receive either VVN539 ophthalmic solution 0.02%, 0.04%, or vehicle once-daily (QD) in the morning (5 days), once-daily in the evening (6 days) and then twice-daily (6 days).

Main Outcome Measures

Comparison of VVNM539 to its vehicle in mean intraocular pressure (IOP) at each diurnal time point (8:00am, 10:00am, and 4:00pm) at visit 4 (day 7), visit 5 (day 14), and visit 6 (day 21).

Results

Mean IOP decreased throughout dosing in the active groups to between 18 and 20 mmHg in both active groups, to between 22 to 23 mmHg in the vehicle group. VVN539 0.04% was statistically superior to vehicle at all 9 diurnal time points (QD AM, QD PM, and twice daily, P ≤ 0.0109). VVN539 0.02% was statistically superior to vehicle at only 6 of 9 diurnal time points (selected QD times and twice daily). The most common ocular treatment-emergent adverse event was conjunctival hyperemia (11 [47.8%], 10 [4.5%], and 1 [4.3%]), followed by ocular hyperemia (3 [13.0%], 5 [22.7%] and 0), respectively. There were no clinically significant changes of note in visual acuity, biomicroscopy, dilated ophthalmoscopy, blood chemistry, hematology, or cardiovascular measures.

Conclusions

In conclusion, the results of this initial phase II study indicate that VVN539 ophthalmic solution showed clinically and statistically significant ocular hypertensive activity and was relatively well tolerated for the treatment of subjects with primary open-angle glaucoma or OHT. Additional studies will be required for a more complete evaluation of the utility of VVN539 ophthalmic solution.

Financial Disclosures

Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Therapeutic benefits of nitric oxide in lung transplantation

Lung transplantation is an evolutionary procedure from its experimental origin in the twentieth century and is now recognized as an established and routine life-saving intervention for a variety of end-stage pulmonary diseases refractory to medical management. Despite the success and continuous refinement in lung transplantation techniques, the widespread application of this important life-saving intervention is severely hampered by poor allograft quality offered from donors-after-brain-death. This has necessitated the use of lung allografts from donors-after-cardiac-death (DCD) as an additional source to expand the pool of donor lungs. Remarkably, the lung exhibits unique properties that may make it ideally suitable for DCD lung transplantation. However, primary graft dysfunction (PGD), allograft rejection and other post-transplant complications arising from unavoidable ischemia-reperfusion injury (IRI) of transplanted lungs, increase morbidity and mortality of lung transplant recipients annually. In the light of this, nitric oxide (NO), a selective pulmonary vasodilator, has been identified as a suitable agent that attenuates lung IRI and prevents PGD when administered directly to lung donors prior to donor lung procurement, or to recipients during and after transplantation, or administered indirectly by supplementing lung preservation solutions. This review presents a historical account of clinical lung transplantation and discusses the lung as an ideal organ for DCD. Next, the author highlights IRI and its clinical effects in lung transplantation. Finally, the author discusses preservation solutions suitable for lung transplantation, and the protective effects and mechanisms of NO in experimental and clinical lung transplantation.

Nitric oxide boosters as defensive agents against COVID-19 infection: an opinion

In the prevailing covid times, scientific community is busy in developing vaccine against COVID-19. Under such fascination this article describes the possible role of nitric oxide (NO) releasers in aiding the immune system of a human body against this dreadful pandemic disease. Despite some prodrug antiviral compounds are in practice to recover the patients suffering from covid-19, however, co-morbidity deaths are highest among the total deaths happened so far. This concurrence of a number of diseases in a patient along with this viral infection is indicative of the poor immunity. Literature background supports the use of NO as immunity boosting agent and hence, the nitric oxide releasing compounds could act as lucrative in this context. Some dietary suggestions of NO-containing food items have also been introduced in this article. Also, the profound effect of NO in relieving symptomatic severity of covid-19 has been opined in this work.Communicated by Ramaswamy H. Sarma.

Gemfibrozil derivatives as activators of soluble guanylyl cyclase - A structure-activity study

Previous studies demonstrated that anti-hyperlipidemic drug gemfibrozil acts as NO- and heme-independent activator of NO receptor soluble guanylyl cyclase. A series of new gemfibrozil derivatives were synthesized and evaluated for sGC activation. The structure-activity relationship study identified the positions in gemfibrozil's scaffold that are detrimental for sGC activation and those that are amendable for optimizing modifications. Compared with gemfibrozil, compounds 7c and 15b were more potent activators of cGMP-forming activity of purified sGC and exhibited enhanced relaxation of preconstricted mouse thoracic aorta rings. These studies established the overall framework needed for futher improvement of sGC activators based on gemfibrozil scaffold.

Nitric oxide as a therapeutic option for COVID-19 treatment: a concise perspective

Among several possible therapies applicable for treating COVID-19, nitric oxide therapy has also gained considerable interest. This article describes the same with mechanistic details.

Homogeneous single-label cGMP detection platform for the functional study of nitric oxide-sensitive (soluble) guanylyl cyclases and cGMP-specific phosphodiesterases

Cardiovascular diseases are the number one death worldwide. Nitric oxide (NO)-NO-sensitive (soluble) guanylyl cyclase (sGC)-cyclic guanosine monophosphate (cGMP) pathway regulates diverse set of important physiological functions, including maintenance of cardiovascular homeostasis. Resting and activated sGC enzyme converts guanosine triphosphate to an important second messenger cGMP. In addition to traditional NO generators, a number of sGC activators and stimulators are currently in clinical trials aiming to support or increase sGC activity in various pathological conditions. cGMP-specific phosphodiesterases (PDEs), which degrade cGMP to guanosine monophosphate, play key role in controlling the cGMP level and the strength or length of the cGMP-dependent cellular signaling. Thus, PDE inhibitors also have clear clinical applications. Here, we introduce a homogeneous quenching resonance energy transfer (QRET) for cGMP to monitor both sGC and PDE activities using high throughput screening adoptable method. We demonstrate that using cGMP-specific antibody, sGC or PDE activity and the effect of small molecules modulating their function can be studied with sub-picomole cGMP sensitivity. The results further indicate that the method is suitable for monitoring enzyme reactions also in complex biological cellular homogenates and mixture.

Cytoprotective Effects of Dinitrosyl Iron Complexes on Viability of Human Fibroblasts and Cardiomyocytes

Nitric oxide (NO) is an important signaling molecule that plays a key role in maintaining vascular homeostasis. Dinitrosyl iron complexes (DNICs) generating NO are widely used to treat cardiovascular diseases. However, the involvement of DNICs in the metabolic processes of the cell, their protective properties in doxorubicin-induced toxicity remain to be clarified. Here, we found that novel class of mononuclear DNICs with functional sulfur-containing ligands enhanced the cell viability of human lung fibroblasts and rat cardiomyocytes. Moreover, DNICs demonstrated remarkable protection against doxorubicin-induced toxicity in fibroblasts and in rat cardiomyocytes (H9c2 cells). Data revealed that the DNICs compounds modulate the mitochondria function by decreasing the mitochondrial membrane potential (ΔΨm). Results of flow cytometry showed that DNICs were not affected the proliferation, growth of fibroblasts. In addition, this study showed that DNICs did not affect glutathione levels and the formation of reactive oxygen species in cells. Moreover, results indicated that DNICs maintained the ATP equilibrium in cells. Taken together, these findings show that DNICs have protective properties in vitro. It was further suggested that DNICs may be uncouplers of oxidative phosphorylation in mitochondria and protective mechanism is mainly provided by the leakage of excess charge through the mitochondrial membrane. It is assumed that the DNICs have the therapeutic potential for treating cardiovascular diseases and for decreasing of chemotherapy-induced cardiotoxicity in cancer survivors.

Nitric oxide-releasing molecules at the interface of inorganic chemistry and biology: a concise overview

The useful aspects of nitric oxide (NO) are nowadays widely known. Due to the need for this molecule in the maintenance of homeostasis, NO-releasing compounds are tested every year to optimize its levels in a patient suffering from low NO production. This manuscript is an update of some important historical concerns about nitrosyl complexes having the ability to act as NO-releasing compounds under the influence of different chemically modified environments. At present, the search for efficient and less harmful NO-releasing molecules at desirable targets and concentrations has gained considerable momentum in nitrosyl chemistry. Iron, ruthenium, and manganese nitrosyls have been investigated elitely to disentangle their electronic transition (excitation) under visible light to act as NO donors without harming the healthy cells of a target. There is much evidence supporting the increase of NO lability if amino acids are used as complexing ligands, the design of a reduction center close to an NO grouping, and the development of porphyrin system-based nitrosyl complexes. From the overall survey, it may be concluded that the desirable properties of such scaffolds need to be evaluated further to complement the biological milieu.

Design, Synthesis and Biological Evaluation of Nitrate Derivatives of Sauropunol A and B as Potent Vasodilatory Agents

A group of nitrate derivatives of naturally occurring sauropunol A and B were designed and synthesized. Nitric oxide (NO) releasing capacity and vasodilatory capacity studies were performed to explore the structure-activity relationship of resulted nitrates. Biological evaluation of these compounds revealed that most of the synthesized mononitrate derivatives demonstrated superior releasing capacity than isosorbide mononitrate (ISMN), and 2MNS-6 even demonstrated stronger NO releasing capacity than isosorbide dinitrate (ISDN). Two dinitrates, DNS-1 and DNS-2, showed higher NO releasing capacity than ISDN. Evaluation of inhibitory activities to the contractions in mesenteric artery rings revealed that 2MNS-8 and DNS-2 showed stronger vasorelaxation activities than ISDN. High level of NO and soluble guanylyl cyclase (sGC) may be essential for the potent vasodilatory effect of DNS-2. The vasodilatory effects of DNS-2 may result from cellular signal transduction of NO-sGC-cGMP. DNS-2 was found to be the most potent sauropunol-derived nitrate vasodilatory agent for further pharmaceutical investigation against cardiovascular diseases.

Effectiveness of vinpocetine and isosorbide-5-mononitrate on experimental schistosomiasis mansoni: Biochemical and immunohistochemical study

Schistosomiasis is one of the most important tropical and subtropical devastating diseases, where praziquantel is the sole drug of choice. Praziquantel effectively kills the adult worms, however, drug resistance has been repeatedly reported. Moreover, there is currently no efficient anti-fibrotic therapy available for chronic schistosomiasis. So, novel drugs which exert anti-fibrotic efficacy are urgently needed. This research is complementary to our previous work that evaluated the anti-schistosomal effects of the anti-inflammatory vinpocetine, as well as the vasodilator and the anti-oxidant isosorbide-5-mononitrate. In the present study, we assessed the therapeutic efficacies of drugs in Swiss albino female mice experimentally infected with an Egyptian strain of Schistosoma mansoni, using some biochemical and immunohistochemical parameters. Our results revealed that both vinpocetine and isosorbide-5-mononitrate monotherapy significantly decreased hepatic nuclear factor-kappaB, 10 weeks post infection. The best effects were seen in mice administered praziquantel combined with isosorbide-5-mononitrate, as detected by reduction in hydroxyproline and collagen contents of the liver, and significant increase in the hepatic nitric oxide content. The data provides insight into the potential effects of the assessed drugs with isosorbide-5-mononitrate being more superior to vinpocetine, hence it can be used as novel adjuvant to praziquantel to alleviate schistosomal hepatic fibrosis. However, molecular mechanism/s and clinical trials are worthy to be scrutinized.

The efficacy and safety of soluble guanylate cyclase stimulators in patients with heart failure: A systematic review and meta-analysis

BACKGROUND

Several randomized controlled trials (RCTs) have been investigated the benefits of soluble guanylate cyclase (sGC) stimulators in the treatment of heart failure, but a comprehensive evaluation is lacking. We performed a meta-analysis to evaluate the efficacy and safety of oral sGC stimulators (vericiguat and riociguat) in patients with heart failure.

METHODS

Studies were searched and screened in PubMed, Embase, and Cochrane Library. Eligible RCTs were included that reported mortality, the change of EuroQol Group 5-Dmensional Self-report Questionnaire (EQ-5D) US index, N-terminal pro-B-type natriuretic peptide (NT-proBNP), or serious adverse events (SAEs). Relative risk or weight mean difference (WMD) was estimated using fixed effect model or random effect model. Analysis of sensitivity and publication bias was conducted.

RESULTS

Five trials with a total of 1200 patients were included. sGC stimulators had no impact on the mortality (1.25; 95% confidence interval 0.50-3.11) and significantly improved EQ-5D US index (0.04; 95% confidence interval 0.020-0.05). Furthermore, in comparison with control group, NT-proBNP was statistically decreased in riociguat group (-0.78; 95% confidence interval -1.01 to -0.47), but not in vericiguat group (0.04, 95% confidence interval -0.18 to 0.25). There were not obverse differences in SAEs between sGC stimulators and control groups (0.90; 95% confidence interval 0.72-1.12).

CONCLUSION

Our meta-analysis suggests that sGC stimulators could improve the quality of life in patients with heart failure with good tolerance and safety, but their long-term benefits need to be observed in the future. sGC stimulators are likely to be promising add-on strategies for the treatment of heart failure.

Anesthetic Treatment of Cardiac Disease During Pregnancy

PURPOSE OF REVIEW

This review summarizes the pathophysiology, peripartum treatment, and anesthetic management of parturients with cardiac disease. Valvular disease, coronary disease, and cardiomyopathy are specifically addressed in the context of the normal physiologic changes of pregnancy. We offer recommendations for anesthetic approaches, hemodynamic goals with an emphasis on interdisciplinary planning between anesthesiologists, cardiologists, cardiothoracic surgeons, obstetricians, maternal fetal medicine specialists, and neonatologists.

RECENT FINDINGS

Vaginal delivery with neuraxial analgesia can be well tolerated by many pregnant patients with cardiac disease when coordinated by an interdisciplinary team of experts. Cardiac disease in pregnancy can present a significant challenge for the interdisciplinary care team. A detailed understanding of each patient's cardiac pathology and the physiologic changes of pregnancy are critical to ensure a safe and successful labor and delivery. Optimized medical therapy in the peripartum period and neuraxial anesthesia with the judicious use of vasoactive agents can be of great benefit for these parturients. As is generally the case, cesarean delivery should be primarily reserved for obstetric indications and maternal wellbeing, with careful consideration of the fetus to guide best practices.

Crystal structure, Hirshfeld surface analysis and energy framework calculation of the first oxoanion salt containing 1,3-cyclo-hexa-nebis(methyl-ammonium): [3-(aza-niumylmeth-yl)cyclo-hex-yl]methanaminium dinitrate

The title salt, C8H20N22+·2NO3-, was obtained by a reaction between 1,3-cyclohexa-nebis(methyl-amine) and nitric acid. The cyclo-hexane ring of the organic cation is in a chair conformation with the methyl-ammonium substituents in the equatorial positions and the two terminal ammonium groups in a trans conformation. In the crystal, mixed cation-anion layers lying parallel to the (010) plane are formed through N-H⋯O hydrogen-bonding inter-actions; these layers are formed by infinite undulating chains running parallel to the [001] direction. The overall inter-molecular inter-actions involved in the structure were qu-anti-fied and fully described by Hirshfeld surface analysis. In addition, energy-framework calculations were used to analyse and visualize the three-dimensional topology of the crystal packing. The electrostatic energy framework is dominant over the dispersion energy framework.

Effects of the NO/soluble guanylate cyclase/cGMP system on the functions of human platelets

Platelets are circulating sentinels of vascular integrity and are activated, inhibited, or modulated by multiple hormones, vasoactive substances or drugs. Endothelium- or drug-derived NO strongly inhibits platelet activation via activation of the soluble guanylate cyclase (sGC) and cGMP elevation, often in synergy with cAMP-elevation by prostacyclin. However, the molecular mechanisms and diversity of cGMP effects in platelets are poorly understood and sometimes controversial. Recently, we established the quantitative human platelet proteome, the iloprost/prostacyclin/cAMP/protein kinase A (PKA)-regulated phosphoproteome, and the interactions of the ADP- and iloprost/prostacyclin-affected phosphoproteome. We also showed that the sGC stimulator riociguat is in vitro a highly specific inhibitor, via cGMP, of various functions of human platelets. Here, we review the regulatory role of the cGMP/protein kinase G (PKG) system in human platelet function, and our current approaches to establish and analyze the phosphoproteome after selective stimulation of the sGC/cGMP pathway by NO donors and riociguat. Present data indicate an extensive and diverse NO/riociguat/cGMP phosphoproteome, which has to be compared with the cAMP phosphoproteome. In particular, sGC/cGMP-regulated phosphorylation of many membrane proteins, G-proteins and their regulators, signaling molecules, protein kinases, and proteins involved in Ca²⁺ regulation, suggests that the sGC/cGMP system targets multiple signaling networks rather than a limited number of PKG substrate proteins.

High sucrose/fat diet and isosorbide mononitrate increase insulin resistance, nitric oxide production and myocardial apoptosis in a hypertensive rat model

The present study aimed to investigate the association between insulin resistance (IR), nitric oxide (NO) production and myocardial apoptosis in a background of coexisting hypertension in a rodent animal model. A hypertensive rat model was established by feeding Wistar and spontaneously hypertensive rats (SHR) with a high sucrose/fat (HSF) diet for 12 weeks, in conjunction with isosorbide mononitrate (ISMN). Increased IR, NO content, apoptotic gene and protein expression, and morphological alterations within rat myocardium were evaluated. Following a total of 12 weeks of feeding with HSF and ISMN resulted in increased IR and NO content within the myocardial tissue of Wistar and SHR rats. HSF and ISMN activated myocardial apoptosis by downregulating the gene transcription and protein expression levels of the anti‑apoptotic B‑cell lymphoma 2 (Bcl‑2), and increasing the pro‑apoptotic Bcl‑2 associated X protein. Apoptosis was demonstrated by DNA fragmentation in terminal deoxynucleotidyl‑transferase‑mediated dUTP nick end labelling assay. In all experiments, the combination of HSF and ISMN was associated with more pronounced effects, indicating the possible synergistic effects. In addition, the correlation analysis in the Wistar rats fed with HSF only, revealed a positive association between NO production and IR. The results of the present study indicated that HSF and ISMN simultaneously increased IR, NO production and myocardial apoptosis in the hypertensive rat model, and may therefore contribute to investigations into the long‑term clinical use of ISMN in hypertensive patients.

Nicorandil and Long-acting Nitrates: Vasodilator Therapies for the Management of Chronic Stable Angina Pectoris

Nicorandil and long-acting nitrates are vasodilatory drugs used commonly in the management of chronic stable angina pectoris. Both nicorandil and long-acting nitrates exert anti-angina properties via activation of nitric oxide (NO) signalling pathways, triggering vascular smooth muscle cell relaxation. Nicorandil has additional actions as an arterial K⁺ _ATP channel agonist, resulting in more "balanced" arterial and venous vasodilatation than nitrates. Ultimately, these drugs prevent angina symptoms through reductions in preload and diastolic wall tension and, to a lesser extent, epicardial coronary artery dilatation and lowering of systemic blood pressure. While there is some evidence to suggest a modest reduction in cardiovascular events among patients with stable angina treated with nicorandil compared to placebo, this prognostic benefit has yet to be proven conclusively. In contrast, there is emerging evidence to suggest that chronic use of long-acting nitrates might cause endothelial dysfunction and increased cardiovascular risk in some patients.

Responsiveness of internal thoracic arteries to nitroglycerin in patients with renal failure

Nitroglycerin is commonly used as an antispasmodic for treating spasm of coronary artery bypass grafts. This study investigated whether the presence of renal failure affects reactivity to nitroglycerin in internal thoracic arteries obtained from patients undergoing coronary bypass surgery. The patients were divided into three groups according to estimated glomerular filtration rate (eGFR, mL/min/1.73 m²): without renal failure (60 ≤ eGFR, n = 13), with moderate renal failure (30 ≤ eGFR < 60, n = 10), and with severe renal failure (eGFR < 30, n = 10). Organ chamber technique was used to evaluate concentration-related responses of isolated internal thoracic arteries to vasodilators. Nitroglycerin induced a concentration-dependent relaxation, which was significantly augmented in patients with severe but not moderate renal failure than in those without renal failure. In addition, there was a negative correlation between eGFR and the relaxant efficacy of nitroglycerin (P = 0.016). On the other hand, relaxant responses to BAY 60-2770 (which enhances cGMP generation as with nitroglycerin) were similar among three grades of renal function. An inverse relationship of eGFR to the relaxant efficacy of BAY 60-2770 was not observed, either (P = 0.314). These findings suggest that severe renal failure specifically potentiates nitroglycerin-induced relaxation in internal thoracic artery grafts.

A comparative study on the anti-schistosomal and hepatoprotective effects of vinpocetine and isosorbide-5-mononitrate on Schistosoma mansoni-infected mice

Schistosomiasis is a remarkable public health problem in developing countries. Presently, praziquantel is the optional drug for all human schistosomiasis. Owing to the increased praziquantel resistance, there is an urgent need to develop new alternatives. This study aims at determining the anti-schistosomal and/or the hepatoprotective effects of the anti-inflammatory drug; vinpocetine, and the vasodilator and the nitric oxide donor; isosorbide-5-mononitrate, in comparison to praziquantel. In the present research, the therapeutic efficacies of these drugs were assessed in Swiss albino female mice (CD-I strain) experimentally infected with an Egyptian strain of Schistosoma mansoni, using some general, parasitological, and histopathological parameters. In this work, praziquantel significantly reduced worm burden and hepatic egg load, increased the percentage of dead eggs in the small intestine and decreased granuloma count, but did not reduce granuloma diameter. While, either vinpocetine or isosorbide-5-mononitrate monotherapy did not induce significant reduction in the worm count, hepatic egg load or shift in the oogram pattern, but significantly reduced granuloma count and diameter. Moreover, isosorbide-5-mononitrate significantly reduced hepatic inflammation and necrosis. The best results were obtained in the mice groups treated with isosorbide-5-mononitrate combined with praziquantel or vinpocetine. Our results point to vinpocetine and isosorbide-5-mononitrate as a convenient and promising adjuvant to praziquantel for ameliorating schistosomal liver pathology. Further studies are recommended to reveal the actual pathways responsible for the different activities of vinpocetine and isosorbide-5-mononitrate.

Methods to assess bioresorbable vascular scaffold devices behaviour after implantation

Bioresorbable vascular scaffolds (BRS) represent a novel approach for coronary revascularization offering several advantages as compared to current generation DES, potentially reducing rate of late adverse events and avoiding permanent vessel caging. Nevertheless, safety concerns have been raised for an increased risk of scaffold thrombosis (ScT) in both early and late phases, probably related to a suboptimal scaffold implantation. In this context, the use of different imaging methodologies has been strongly suggested in order to guarantee an optimal implantation. We herein analyze the different imaging methodologies available to assess BRS after implantation and at follow-up.

Adverse Drug Reactions in the Intensive Care Unit

Adverse drug reactions (ADRs) are undesirable effects of medications used in normal doses [1]. ADRs can occur during treatment in an intensive care unit (ICU) or result in ICU admissions. A meta-analysis of 4139 studies suggests the incidence of ADRs among hospitalized patients is 17% [2]. Because of underreporting and misdiagnosis, the incidence of ADRs may be much higher and has been reported to be as high as 36% [3]. Critically ill patients are at especially high risk because of medical complexity, numerous high-alert medications, complex and often challenging drug dosing and medication regimens, and opportunity for error related to the distractions of the ICU environment [4]. Table 1 summarizes the ADRs included in this chapter.

Nitrates for the prevention of cardiac morbidity and mortality in patients undergoing non-cardiac surgery

BACKGROUND

Cardiac complications are not uncommon in patients undergoing non-cardiac surgery, especially in patients with coronary artery disease (CAD) or at high risk of CAD. Perioperative cardiac complications can lead to mortality and morbidity, as well as higher costs for patient care. Nitrates, which are among the most commonly used cardiovascular drugs, perform the function of decreasing cardiac preload while improving cardiac blood perfusion. Sometimes, nitrates are administered to patients undergoing non-cardiac surgery to reduce the incidence of cardiac complications, especially for patients with CAD. However, their effects on patients' relevant outcomes remain controversial.

OBJECTIVES

• To assess effects of nitrates as compared with other interventions or placebo in reducing cardiac risk (such as death caused by cardiac factors, angina pectoris, acute myocardial infarction, acute heart failure and cardiac arrhythmia) in patients undergoing non-cardiac surgery.• To identify the influence of different routes and dosages of nitrates on patient outcomes.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE and the Chinese BioMedical Database until June 2014. We also searched relevant conference abstracts of important anaesthesiology or cardiology scientific meetings, the database of ongoing trials and Google Scholar.We reran the search in January 2016. We added three potential new studies of interest to the list of 'Studies awaiting classification' and will incorporate them into our formal review findings for the review update.

SELECTION CRITERIA

We included randomized controlled trials (RCTs) comparing nitrates versus no treatment, placebo or other pharmacological interventions in participants (15 years of age and older) undergoing non-cardiac surgery under any type of anaesthesia.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures as expected by Cochrane. Two review authors selected trials, extracted data from included studies and assessed risk of bias. We resolved differences by discussion and, when necessary, sought help and suggestions from a third review author. We used a random-effects model for data analysis.

MAIN RESULTS

We included 27 randomized controlled trials (RCTs) (8244 participants analysed). Investigators reported 12 different comparisons of three different nitrates (nitroglycerin, isosorbide dinitrate and nicorandil) versus no treatment, placebo or other pharmacological interventions. All participants were older than 15 years of age. More than half of the trials used general anaesthesia. Surgical procedures in most trials were at low to moderate risk for perioperative cardiac complications. Only two comparisons including three studies reported the primary outcome - all-cause mortality up to 30 days post operation. Researchers reported other morbidity outcomes and adverse events in a variable and heterogeneous way, resulting in limited available data for inclusion in the meta-analysis. We determined that the overall methodological quality of included studies was fair to low, in accordance with risk of bias in most domains.In summary, we found no difference in the primary outcome - all-cause mortality up to 30 days post operation - when nitroglycerin was compared with no treatment (one study, 60 participants, 0/30 vs 1/30; (risk ratio (RR) 0.33, 95% confidence interval (CI) 0.01 to 7.87, very low-quality evidence based on GRADE criteria) or with placebo (two studies, 89 participants, 1/45 vs 0/44; RR 2.81, 95% CI 0.12 to 63.83, very low-quality evidence). Regarding our secondary outcomes, we noted no statistically significant differences in angina pectoris, acute myocardial infarction, acute heart failure, cardiac arrhythmia or cardiac arrest in any comparisons. In comparisons versus nitroglycerin, although more events of cardiac ischaemia were observed in participants receiving no treatment or placebo, we found no statistically significant differences in any comparisons, except the comparison of nicorandil versus placebo. One study revealed a potential dose-dependent protective effect of nicorandil for cardiac ischaemia.Adverse events were reported in a heterogeneous way among the comparisons. In general, more participants treated with nitrates had hypotension, tachycardia and headache, but investigators reported no statistically significant differences between groups in any comparisons.

AUTHORS' CONCLUSIONS

This systematic review suggests that nitroglycerin or isosorbide dinitrate is not associated with improvement in mortality and cardiac complications among patients undergoing non-cardiac surgery. Limited evidence suggests that nicorandil may reduce the risk of cardiac ischaemia in participants undergoing non-cardiac surgery. Additional studies are needed to consolidate the evidence.However, the data included in many of the analyses in this review are sparse - that is, adequate data are few - resulting in very low power to detect differences between nitrates and comparators. Thus, a more objective conclusion would state that available evidence is insufficient to show whether nitrates are associated with improvement in mortality and cardiac complications among patients undergoing non-cardiac surgery.Over the past decade, no high-quality studies have focused on association of cardiac mortality and morbidity with use of nitrates during non-cardiac surgery. This review underlines the need for well-designed trials in this field.

Vasodilator Therapy: Nitrates and Nicorandil

Nitrates have been used to treat symptoms of chronic stable angina for over 135 years. These drugs are known to activate nitric oxide (NO)-cyclic guanosine-3',-5'-monophasphate (cGMP) signaling pathways underlying vascular smooth muscle cell relaxation, albeit many questions relating to how nitrates work at the cellular level remain unanswered. Physiologically, the anti-angina effects of nitrates are mostly due to peripheral venous dilatation leading to reduction in preload and therefore left ventricular wall stress, and, to a lesser extent, epicardial coronary artery dilatation and lowering of systemic blood pressure. By counteracting ischemic mechanisms, short-acting nitrates offer rapid relief following an angina attack. Long-acting nitrates, used commonly for angina prophylaxis are recommended second-line, after beta-blockers and calcium channel antagonists. Nicorandil is a balanced vasodilator that acts as both NO donor and arterial K(+) ATP channel opener. Nicorandil might also exhibit cardioprotective properties via mitochondrial ischemic preconditioning. While nitrates and nicorandil are effective pharmacological agents for prevention of angina symptoms, when prescribing these drugs it is important to consider that unwanted and poorly tolerated hemodynamic side-effects such as headache and orthostatic hypotension can often occur owing to systemic vasodilatation. It is also necessary to ensure that a dosing regime is followed that avoids nitrate tolerance, which not only results in loss of drug efficacy, but might also cause endothelial dysfunction and increase long-term cardiovascular risk. Here we provide an update on the pharmacological management of chronic stable angina using nitrates and nicorandil.

Recent trends in the development of vitamin B12 derivatives for medicinal applications

This Feature Article highlights recent developments in the field of vitamin B12 derivatives for medicinal applications. The following topics are emphasized: (1) the development of aquacorrinoids for cyanide detection and detoxification, (2) the use of vitamin B12 conjugates and (3) antivitamins B12 for therapy and diagnosis, and (4) the design of corrinoids as activators of soluble guanylyl cyclase (sGC).

Synthesis of 2-[(18)F]Fluoro-2-deoxyisosorbide 5-mononitrate and Assessment of Its in vivo Biodistribution as Determined by Dynamic Positron Emission Tomography (PET)

Herein we disclose the synthesis of 2-fluoro-2-deoxyisosorbide 5-mononitrate (2F-IS-5MN), a fluorinated analogue of the commonly prescribed vasodilator isosorbide 5-mononitrate (IS-5MN). X-ray structural data for IS-5MN and its C2-epimeric congener IM-5MN are presented together with structural data for 2F-IS-5MN. Radioisotope labeling of 2F-IS-5MN has, for the first time, allowed observation of the in vivo biodistribution of this organic nitrate by means of dynamic positron emission tomography (PET) in wild-type mice.

Nitrosyl iron complexes with enhanced NO donating ability: synthesis, structure and properties of a new type of salt with the DNIC cations [Fe(SC(NH2)2)2(NO)2]+

A new structural type of water-soluble iron nitrosyl complexes with thiocarbamide has been obtained.

Recent insights in the paracrine modulation of cardiomyocyte contractility by cardiac endothelial cells

The cardiac endothelium is formed by a continuous monolayer of cells that line the cavity of the heart (endocardial endothelial cells (EECs)) and the luminal surface of the myocardial blood vessels (intramyocardial capillary endothelial cells (IMCEs)). EECs and IMCEs can exercise substantial control over the contractility of cardiomyocytes by releasing various factors such as nitric oxide (NO) via a constitutive endothelial NO-synthase (eNOS), endothelin-1, prostaglandins, angiotensin II, peptide growth factors, and neuregulin-1. The purpose of the present paper is actually to shortly review recent new information concerning cardiomyocytes as effectors of endothelium paracrine signaling, focusing particularly on contractile function. The modes of action and the regulatory paracrine role of the main mediators delivered by cardiac endothelial cells upon cardiac contractility identified in cardiomyocytes are complex and not fully described. Thus, careful evaluation of new therapeutic approaches is required targeting important physiological signaling pathways, some of which have been until recently considered as deleterious, like reactive oxygen species. Future works in the field of cardiac endothelial cells and cardiac function will help to better understand the implication of these mediators in cardiac physiopathology.

Synthesis and chemical and biological comparison of nitroxyl- and nitric oxide-releasing diazeniumdiolate-based aspirin derivatives

Structural modifications of nonsteroidal anti-inflammatory drugs (NSAIDs) have successfully reduced the side effect of gastrointestinal ulceration without affecting anti-inflammatory activity, but they may increase the risk of myocardial infarction with chronic use. The fact that nitroxyl (HNO) reduces platelet aggregation, preconditions against myocardial infarction, and enhances contractility led us to synthesize a diazeniumdiolate-based HNO-releasing aspirin and to compare it to an NO-releasing analogue. Here, the decomposition mechanisms are described for these compounds. In addition to protection against stomach ulceration, these prodrugs exhibited significantly enhanced cytotoxcity compared to either aspirin or the parent diazeniumdiolate toward nonsmall cell lung carcinoma cells (A549), but they were not appreciably toxic toward endothelial cells (HUVECs). The HNO-NSAID prodrug inhibited cylcooxgenase-2 and glyceraldehyde 3-phosphate dehydrogenase activity and triggered significant sarcomere shortening on murine ventricular myocytes compared to control. Together, these anti-inflammatory, antineoplasic, and contractile properties suggest the potential of HNO-NSAIDs in the treatment of inflammation, cancer, or heart failure.

Nitric oxide synthases in heart failure

SIGNIFICANCE

The regulation of myocardial function by constitutive nitric oxide synthases (NOS) is important for the maintenance of myocardial Ca(2+) homeostasis, relaxation and distensibility, and protection from arrhythmia and abnormal stress stimuli. However, sustained insults such as diabetes, hypertension, hemodynamic overload, and atrial fibrillation lead to dysfunctional NOS activity with superoxide produced instead of NO and worse pathophysiology.

RECENT ADVANCES

Major strides in understanding the role of normal and abnormal constitutive NOS in the heart have revealed molecular targets by which NO modulates myocyte function and morphology, the role and nature of post-translational modifications of NOS, and factors controlling nitroso-redox balance. Localized and differential signaling from NOS1 (neuronal) versus NOS3 (endothelial) isoforms are being identified, as are methods to restore NOS function in heart disease.

CRITICAL ISSUES

Abnormal NOS signaling plays a key role in many cardiac disorders, while targeted modulation may potentially reverse this pathogenic source of oxidative stress.

FUTURE DIRECTIONS

Improvements in the clinical translation of potent modulators of NOS function/dysfunction may ultimately provide a powerful new treatment for many hearts diseases that are fueled by nitroso-redox imbalance.

Involvement of guanylate cyclase and K+ channels in relaxation evoked by ferulate nitrate in rat aorta artery

Vasorelaxant properties of N-2-(ferulamidoethyl)-nitrate (ferulate nitrate, FLNT), a newly synthesized nitrate, were compared with those of isosorbide dinitrate, nicorandil, nitroglycerin, and 8-bromoguanosine 3,5-cyclic monophosphate (8-Br-cGMP) in rat aorta pre-contracted by phenylephrine. FLNT produced vasorelaxation in a concentration-dependent manner (0.1 - 100 µM). The degree of relaxation induced by FLNT was similar to that induced by isosorbide dinitrate. In addition, removal of endothelium did not affect the relaxant effect of FLNT. FLNT caused a rightward shift of the cumulative concentration-response curves of phenylephrine and reduced the maximal efficacy of contraction. 1H-[1,2,4]Oxadiazolo-[4,3-a]quinoxalin-1-one (ODQ, 10 µM) and K(+)-channel blockers charybdotoxin (CHT, 0.1 µM) and BaCl(2) (1 µM) reduced the relaxant effect of FLNT in the endothelium-denuded arteries, whereas glibenclamide (1 µM) and 4-aminopyridine (1 mM) failed to influence FLNT-induced vasorelaxation. Furthermore, in the presence of ODQ, both CHT (0.1 µM) and BaCl(2) (1 µM) still significantly reduced the relaxation evoked by FLNT. Pretreatment of vessels with hydroxocobalamin, a nitric oxide scavenger, abolished the FLNT effect. These findings demonstrate that FLNT induces relaxation of the rat aorta rings endothelium-independently. Furthermore, we demonstrated that FLNT-induced vasorelaxation is related to its stimulation of soluble guanylate cyclase and activation of K(+) channels.

Vitamin B₁₂ derivatives as activators of soluble guanylyl cyclase

Various newly prepared and previously known vitamin B₁₂ derivatives have been studied as potential soluble guanylyl cyclase (sGC) activators. All compounds tested were found to activate the sGC enzyme, although to differing extents. The best results were obtained with the derivatives synthesized from c-lactone and possessing aliphatic amides in the c- and d-positions.

Differential effects of organic nitrates on arterial diameter among healthy Japanese participants with different mitochondrial aldehyde dehydrogenase 2 genotypes: randomised crossover trial

OBJECTIVES

To determine whether polymorphisms at codon 487 (*1, GAA=Glu; *2, AAA=Lys) of mitochondrial aldehyde dehydrogenase 2 (ALDH2) influence nitroglycerine (glyceryl trinitrate (GTN))-induced vasodilation, and whether GTN or isosorbide dinitrate (ISDN) is a more effective antianginal agent in each ALDH2 genotype.

DESIGN

A randomised, open-label, crossover trial with 117 healthy Japanese (20-39 years) whose genotypes were determined (*1/*1, n=47; *1/*2, n=48; *2/*2, n=22) was performed at Kyushu University Hospital, Fukuoka, Japan. Participants were randomly assigned to treatment: sublingual spray of GTN (0.3 mg) or ISDN (1.25 mg). After ≥ 1 week, measurements were repeated using the other drug. The main outcome measures were the maximal rate of increase in the brachial artery diameter determined by ultrasonography, the time required to attain maximal dilation (T(max)) and the time required to attain 90% maximal dilation (T(0.9)).

RESULTS

The maximal artery diameter increase in response to GTN or ISDN did not differ among genotypes. However, GTN T(max) was significantly longer for *2/*2 (299.7 s, 269.0-330.4) than *1/*1 (254.7 s, 238.6-273.4; p=0.0190). GTN T(0.9) was significantly longer in the *1/*2 (206.1 s, 191.7-219.3) and *2/*2 (231.4 s, 211.8-251.0) genotypes than *1/*1 (174.9 s, 161.5-188.3; p=0.0068, p<0.0001, respectively). In contrast, the time-course of ISDN-induced vasodilation did not differ among genotypes. GTN T(max) and T(0.9) among *1 allele carriers (*1/*1 and *1/*2) were significantly shorter than those of ISDN, whereas the time course of GTN and ISDN vasodilation did not differ among participants carrying *2/*2.

CONCLUSIONS

The amplitude of GTN-induced vasodilation was not influenced by the ALDH2 genotype, but the response was significantly delayed in *2 allele carriers, especially *2/*2. GTN dilated the artery more quickly than ISDN in *1/*1 and *1/*2, but not in *2/*2. Trial registration number UMIN000001492 (UMIN-CTR database).

Latest approaches for the treatment of spasticity and autonomic dysreflexia in chronic spinal cord injury

Two of the most prevalent secondary complications following spinal cord injury (SCI), besides loss of function and/or sensation below the level of injury, are uncontrolled muscle spasticity and hypertensive autonomic dysreflexia. Despite the desires of the SCI community, there have been few advances in the treatment and/or management of these fundamental impediments to the quality of life associated with chronic SCI. Therefore, the purpose of this review is to focus on current drug treatment strategies that alleviate symptoms of spasticity and autonomic dysfunction. Subsequently, looking ahead, we discuss whether individuals suffering from autonomic dysreflexia and/or muscle spasms can take certain compounds that specifically and rapidly block the neurotransmission of pain into the injured spinal cord to get rapid relief for both aberrant reflexes for which painful stimuli below the level of SCI are common precipitants.

Severe obesity is associated with impaired arterial smooth muscle function in young adults

The degree of arterial dilatation induced by exogenous nitrates (nitrate-mediated dilatation, NMD) has been similar in obese and normal-weight adults after single high-dose glyceryl trinitrate (GTN). We examined whether NMD is impaired in obesity by performing a GTN dose-response study, as this is a potentially more sensitive measure of arterial smooth muscle function. In this cross-sectional study, subjects were 19 obese (age 31.0 ± 1.2 years, 10 male, BMI 44.1 ± 2.1) and 19 age- and sex-matched normal-weight (BMI 22.4 ± 0.4) young adults. Blood pressure (BP), triglycerides, high-density lipoprotein (HDL), and low-density lipoprotein (LDL)-cholesterol, glucose, insulin, high-sensitivity C-reactive protein (hs-CRP), carotid intima-media thickness (CIMT), and flow-mediated dilatation (FMD) were measured. After incremental doses of GTN, brachial artery maximal percent dilatation (maximal NMD) and the area under the dose-response curve (NMD AUC) were calculated. Maximal NMD (13.4 ± 0.9% vs. 18.3 ± 1.1%, P = 0.002) and NMD AUC (54,316 ± 362 vs. 55,613 ± 375, P = 0.018) were lower in obese subjects. The obese had significantly higher hs-CRP, insulin, and CIMT and lower HDL-cholesterol. Significant bivariate associations existed between maximal NMD or NMD AUC and BMI-group (r = -0.492, P = 0.001 or r = -0.383, P = 0.009), hs-CRP (r = -0.419, P = 0.004 or r = -0.351, P = 0.015), and HDL-cholesterol (r = 0.374, P = 0.01 or r = 0.270, P = 0.05). On multivariate analysis, higher BMI-group remained as the only significant determinant of maximal NMD (r² = 0.242, β = -0.492, P = 0.002) and NMD AUC (r² = 0.147, β = -0.383, P = 0.023). In conclusion, arterial smooth muscle function is significantly impaired in the obese. This may be important in their increased cardiovascular risk.

Clinical pharmacokinetics of the cyclooxygenase inhibiting nitric oxide donator (CINOD) AZD3582

The clinical pharmacokinetics of the COX-inhibiting nitric oxide donator (CINOD) AZD3582 and its metabolites, including naproxen, nitric oxide and nitrate, are summarized. AZD3582 has low aqueous solubility, moderate and passive intestinal permeability and is degraded by intestinal esterases. Its oral bioavailability (F) appears to be maximally a few per cent, and increases by several-fold after food intake. Ninety-four per cent or more of an AZD3582 dose is absorbed, of which at least 9–20% appears to be taken up as intact substance. AZD3582 has a predicted plasma protein binding degree of ∼ 0.1%, a half-life (t½) of 3 to 10 h and does not accumulate after repeated once- and twice-daily dosing. In patients AZD3582 does not provide a significantly better gastrointestinal (GI) side-effect profile than the highly permeable and locally irritating naproxen. Possible reasons for this include considerable GI uptake as naproxen, limited duration and extent of nitric oxide donation in the GI mucosa and the circulation, tolerance development (involving auto-inhibition of nitric oxide catalysing enzymes) and mucosal damage caused by nitric oxide. Blood pressure data suggest that nitric oxide is mainly donated within 3h. The uptake of naproxen is slightly slower and lower (≥ 94% relative GI uptake and 80–85% relative F) after AZD3582 administration compared with naproxen dosing. The naproxen t½ and trough steady-state concentrations after AZD3582 and naproxen dosing are similar. The average systemic nitrate exposure is approximately doubled after dosing of 375 to 750 mg AZD3582 twice daily.

Left ventricular torsion parameters are affected by acute changes in load

BACKGROUND

Quantification of left ventricular torsion may provide new indices of systolic and diastolic function. We sought to characterize the effect of acute manipulation of load on cardiac torsion, plecotropy in human subjects.

METHODS

Simultaneous Millar LV pressure, micromanometry, and echocardiograms were performed on 18 patients (10 male, mean age 66 years) with normal systolic function. Loading was altered sequentially by the administration of glyceryl trinitrate (GTN) and saline fluid loading. Echocardiographic speckle tracking imaging was used to quantify LV torsion and event timing was recorded relative to mitral valve opening (MVO).

RESULTS

GTN administration decreased preload (LV end diastolic pressure: 15.7 vs 8.4 mmHg, P < 0.001), and afterload (wall stress: 140 vs 84 x10(3)dyn/cm(2), P < 0.02). Administration of fluid increased preload (LVEDP 11.3 vs 18.1 mmHg, P < 0.001) and increased wall stress, but to a lesser extent (102 vs 117 x10(3)dyn/cm(2), P < 0.003). GTN administration augmented peak torsion (8.4 vs 11.0 deg, P < 0.05), increased systolic torsion velocity (46.6 vs 65.3deg/sec, P < 0.01) and resulted in earlier onset of untwisting (-105 vs -127ms, P < 0.05). Fluid loading decreased the proportion of untwisting prior to MVO (39.0 vs 31.0%, P < 0.05), untwisting acceleration (-750 vs -592deg/sec/sec, P < 0.05) and delayed the timing of peak untwisting (-37.0 vs 9.1ms, P < 0.01), but did not affect systolic torsion parameters.

CONCLUSIONS

Left ventricular torsion parameters are sensitive to acute changes in load and therefore need to be interpreted in the context of current loading conditions.

Quantitative analysis of cytokine-induced vascular toxicity and vascular leak in the mouse brain

A storm of inflammatory cytokines is released during treatment with pro-inflammatory cytokines, such as interleukin-2 (IL-2), closely approximating changes initially observed during sepsis. These signals induce profound changes in neurologic function and cognition. Little is known about the mechanisms involved. We evaluated a number of experimental methods to quantify changes in brain blood vessel integrity in a well-characterized IL-2 treatment mouse model. Measurement of wet versus dry weight and direct measurement of small molecule accumulation (e.g. [(3)H]-H(2)O, sodium fluorescein) were not sensitive or reliable enough to detect small changes in mouse brain vascular permeability. Estimation of brain water content using proton density magnetic resonance imaging (MRI) measurements using a 7T mouse MRI system was sensitive to 1-2% changes in brain water content, but was difficult to reproduce in replicate experiments. Successful techniques included use of immunohistochemistry using specific endothelial markers to identify vasodilation in carefully matched regions of brain parenchyma and dynamic contrast enhanced (DCE) MRI. Both techniques indicated that IL-2 treatment induced vasodilation of the brain blood vessels. DCE MRI further showed a 2-fold increase in the brain blood vessel permeability to gadolinium in IL-2 treated mice compared to controls. Both immunohistochemistry and DCE MRI data suggested that IL-2 induced toxicity in the brain results from vasodilation of the brain blood vessels and increased microvascular permeability, resulting in perivascular edema. These experimental techniques provide us with the tools to further characterize the mechanism responsible for cytokine-induced neuropsychiatric toxicity.