The Role of Nitroglycerin and Other Nitrogen Oxides in Cardiovascular Therapeutics

Trinitroglycerin-loaded chitosan nanogels accelerate angiogenesis in wound healing process

Trinitroglycerin (TNG) with remarkable angiogenic, antibacterial, and antioxidative activity is a promising candidate to govern wound healing capacity. However, its clinical administration is limited due to associated complications and NO short half-life. In the current study, TNG-loaded chitosan nanogels (TNG-Ngs) were examined in-vitro and in-vivo to gain insight into their clinical application. We prepared TNG-Ngs and characterized their physiochemical properties. The potential of TNG-Ngs was assessed using biocompatibility, scratch assay, and a full-thickness skin wounds model, followed by histopathological and immunohistochemistry examinations. TNG-Ngs particle size 96 ± 18 and definite size distribution histogram. The loading capacity (LC) and encapsulation efficiency (EE) of prepared TNG-Ngs were 70.2 % and 2.1 %, respectively. The TNG-Ngs samples showed enhanced migration of HUVECs with no apparent cytotoxicity. The topical use of TNG-Ngs200 on the wounds revealed a complete wound closure ratio, skin component formation, less scar width, remarkable granulation tissue, promoted collagen deposition, and enhanced the relative mean density of α-SMA and CD31. TNG-Ngs accelerated wound healing by promoting collagen deposition and angiogenic activity, as well as reducing inflammation. The findings indicated that TNG-Ngs is expected to be well vascularized in the wound area and to be more effective in topical therapy.

Computed tomography angiography assessment of Adamkiewicz artery with sublingual nitroglycerin administration

PURPOSE

Identification of the Adamkiewicz artery before aortic surgery is important for preventing postoperative complications due to spinal cord ischemia. The Adamkiewicz artery is difficult to identify due to its small diameter. Nitroglycerin has a vasodilatory effect and is used clinically to improve visualization of blood vessels on coronary computed tomography (CT) angiography. We investigated whether the vasodilatory effect of nitroglycerin could improve the ability to visualize the Adamkiewicz artery.

METHODS

We extracted 33 cases wherein contrast-enhanced CT images were taken before and after aortic aneurysm surgery. Nitroglycerin was administered for coronary artery evaluation on the preoperative CT. However, no nitroglycerin was administered before the postoperative CT. Aortic contrast-to-noise ratio, CT value, image noise, and diameter of the Adamkiewicz artery and anterior spinal artery were measured. The depiction of the Adamkiewicz artery was graded into four grades and evaluated. These measurements were performed by two independent reviewers.

RESULTS

In nitroglycerin-administered cases, the contrast-to-noise ratio and CT values were significantly higher (P < 0.001, P < 0.001, respectively); the Adamkiewicz artery and anterior spinal artery diameters were dilated (P = 0.005, P = 0.001, respectively). The Adamkiewicz artery score also improved significantly (P < 0.001). No significant difference was found in image noise.

CONCLUSION

Nitroglycerin contributed to improving the Adamkiewicz artery's visualization.

Effects of short-term dietary nitrate supplementation on exercise and coronary blood flow responses in patients with peripheral artery disease

Background

Peripheral arterial disease (PAD) is a prevalent vascular disorder characterized by atherosclerotic occlusion of peripheral arteries, resulting in reduced blood flow to the lower extremities and poor walking ability. Older patients with PAD are also at a markedly increased risk of cardiovascular events, including myocardial infarction. Recent evidence indicates that inorganic nitrate supplementation, which is abundant in certain vegetables, augments nitric oxide (NO) bioavailability and may have beneficial effects on walking, blood pressure, and vascular function in patients with PAD.

Objective

We sought to determine if short-term nitrate supplementation (via beetroot juice) improves peak treadmill time and coronary hyperemic responses to plantar flexion exercise relative to placebo (nitrate-depleted juice) in older patients with PAD. The primary endpoints were peak treadmill time and the peak coronary hyperemic response to plantar flexion exercise.

Methods

Eleven PAD patients (52-80 yr.; 9 men/2 women; Fontaine stage II) were randomized (double-blind) to either nitrate-rich (Beet-IT, 0.3 g inorganic nitrate twice/day; BRnitrate) or nitrate-depleted (Beet-IT, 0.04 g inorganic nitrate twice/day, BRplacebo) beetroot juice for 4 to 6 days, followed by a washout of 7 to 14 days before crossing over to the other treatment. Patients completed graded plantar flexion exercise with their most symptomatic leg to fatigue, followed by isometric handgrip until volitional fatigue at 40% of maximum on day 4 of supplementation, and a treadmill test to peak exertion 1-2 days later while continuing supplementation. Hemodynamics and exercise tolerance, and coronary blood flow velocity (CBV) responses were measured.

Results

Although peak walking time and claudication onset time during treadmill exercise did not differ significantly between BRplacebo and BRnitrate, the diastolic blood pressure response at the peak treadmill walking stage was significantly lower in the BRnitrate condition. Increases in CBV from baseline to peak plantar flexion exercise after BRplacebo and BRnitrate showed a trend for a greater increase in CBV at the peak workload of plantar flexion with BRnitrate (p = 0.06; Cohen's d = 0.56).

Conclusion

Overall, these preliminary findings suggest that inorganic nitrate supplementation in PAD patients is safe, well-tolerated, and may improve the coronary hyperemic and blood pressure responses when their calf muscles are most predisposed to ischemia.Clinical trial registration:https://clinicaltrials.gov/, identifier NCT02553733.

NLRP3 inflammasome: a key player in the pathogenesis of life-style disorders

Proinflammatory cytokines and chemokines play a crucial role in regulating the inflammatory response, which is essential for the proper functioning of our immune system. When infections or threats to the body's defense mechanisms are detected, the innate immune system takes the lead. However, an excessive inflammatory response can lead to the production of high concentrations of cytotoxic molecules, resulting in tissue damage. Inflammasomes are significant contributors to innate immunity, and one of the most extensively studied inflammasome complexes is NOD-like receptor 3 (NLRP3). NLRP3 has a wide range of recognition mechanisms that streamline immune activation and eliminate pathogens. These cytosolic multiprotein complexes are composed of effector, adaptor, and sensor proteins, which are crucial for identifying intracellular bacterial breakdown products and initiating an innate immune cascade. To understand the diverse behavior of NLRP3 activation and its significance in the development of lifestyle-related diseases, one must delve into the study of the immune response and apoptosis mediated by the release of proinflammatory cytokines. In this review, we briefly explore the immune response in the context of lifestyle associated disorders such as obesity, hyperlipidemia, diabetes, chronic respiratory disease, oral disease, and cardiovascular disease.

Effectiveness of a Glyceryl Trinitrate (GTN) Patch in Preventing Amputation, Improving Pain Control and Reducing the Size of Tissue Loss for a Patient With Critical Limb-Threatening Ischaemia (CLTI)

Background  Foot ulcer is a common complication of poorly controlled diabetes and peripheral vascular disease (PVD). The current standard of treatment for diabetic foot ulcers includes the management of underlying risk factors, wound debridement, use of antibiotics for infection, off-loading with cast, and revascularisation surgery. The glyceryl trinitrate (GTN) patch is currently off-licence in treating PVD or diabetic foot ulcers. This study aims to evaluate the effectiveness of the GTN patch in preventing amputation, improving pain control, and reducing the size of tissue loss (ulcer/gangrene) or localised ischaemic area. Method This is a pilot study of 30 patients who were started on the GTN patch from February 2020 to October 2021. Inclusion criteria were patients who have critical limb-threatening ischaemia (CLTI) and with no viable options or are at high risk for revascularisation, both endovascular and open surgery. Patients who were on a GTN patch for less than six weeks at the time of data collection or had unclear outcomes were excluded. The outcomes were retrospectively collected on prevention of amputation, improvement in pain control, and reduction in tissue loss (the size of ulcer/gangrene) or localised ischaemic area with the use of a GTN patch. The binomial test was used to compare the observed outcome of the GTN patch and the expected outcome, which was assumed to be 50% in this study. Results  Ninety-three per cent (93%) of the patients who had GTN patches successfully avoided amputation (p<0.0001). Eighty-four per cent (84%) of patients reported better pain control (p=0.0022) and improvement in the size of ulcer/gangrene/localised ischaemic areas (p=0.0005). Conclusion The GTN patch is effective in preventing amputation, improving pain control, and reducing the size of ulcer/gangrene/localised ischaemic areas in patients who have end-stage CLTI and no viable options or who are at high risk for revascularisation surgery.

Nontopical Nitrates in Flap Perfusion and Delay Phenomenon

Background

Topical nitrates have demonstrated efficacy in improving flap perfusion. However, evidence for nontopical nitrates in modulation of flap perfusion dynamics has yet to be consolidated. Here, we review evidence regarding the use of intravascular, sublingual, and oral nitrates in modulating flap perfusion.

Methods

We performed a review of the literature for evidence linking nontopical nitrates and flap perfusion, and included clinical studies, animal studies, and in vitro studies.

Results

Evidence suggests that intravascular, sublingual, and oral nitrates exert vasodilatory properties, which may be harnessed for identification of perforators and improved flap perfusion. We also found evidence suggesting nitrates may facilitate ischemic preconditioning while reducing ischemia-reperfusion injury.

Conclusions

Nitrates delivered intravascularly, sublingually, or orally may increase flap perfusion and serve as a method for ischemic preconditioning, particularly in the intraoperative setting.

Nitric Oxide Releasing Nanomaterials for Cardiovascular Applications

A central paradigm of cardiovascular homeostasis is that impaired nitric oxide (NO) bioavailability results in a wide array of cardiovascular dysfunction including incompetent endothelium-dependent vasodilatation, thrombosis, vascular inflammation, and proliferation of the intima. Over the course of more than a century, NO donating formulations such as organic nitrates and nitrites have remained a cornerstone of treatment for patients with cardiovascular diseases. These donors primarily produce NO in the circulation and are not targeted to specific (sub)cellular sites of action. However, safe, and therapeutic levels of NO require delivery of the right amount to a precise location at the right time. To achieve these aims, several recent strategies aimed at therapeutically generating or releasing NO in living systems have shown that polymeric and inorganic (silica, gold) nanoparticles and nanoscale metal-organic frameworks could either generate NO endogenously by the catalytic decomposition of endogenous NO substrates or can store and release therapeutically relevant amounts of NO gas. NO-releasing nanomaterials have been developed for vascular implants (such as stents and grafts) to target atherosclerosis, hypertension, myocardial ischemia-reperfusion injury, and cardiac tissue engineering. In this review, we discuss the advances in design and development of novel NO-releasing nanomaterials for cardiovascular therapeutics and critically examine the therapeutic potential of these nanoplatforms to modulate cellular metabolism, to regulate vascular tone, inhibit platelet aggregation, and limit proliferation of vascular smooth muscle with minimal toxic effects.

Topical glyceryl trinitrate to increase radial artery diameter in neonates: study protocol for a randomized controlled trial

BACKGROUND

Newborn infants admitted to the neonatal intensive care unit require arterial cannulation for hemodynamic monitoring and blood sampling. Arterial access is achieved through catheterization of umbilical or peripheral arteries. Peripheral artery cannulation is performed in critically ill newborns, but artery localization and cannulation is often challenging and unsuccessful. Therefore, increasing the internal diameter and preventing vasospasm are important for successful peripheral artery cannulation in neonates. Topical glyceryl trinitrate has the potential to increase cannulation success by relaxing arterial smooth muscles and thus increasing the internal diameter. We aim to conduct a pilot randomized controlled trial to evaluate the efficacy and safety of topycal glyceryl trinitrate in increasing the diameter of the radial artery in neonates.

METHODS/DESIGN

This study will be a single-center, observer-blind, randomized, placebo-controlled trial conducted in the neonatal intensive care unit of Perth Children's Hospital, Western Australia. A total of 60 infants born at >34 weeks of gestation who are admitted for elective surgery or medical reasons and for whom a peripheral arterial line is needed for sampling or blood pressure monitoring will be recruited after informed parental consent is obtained. The primary outcome will be the change in radial arterial diameter from baseline to postintervention. Secondary outcomes will be the absolute and percentage change from baseline in the radial arterial diameter in both limbs and safety (hypotension and methemoglobinemia).

DISCUSSION

This will be the first randomized controlled trial evaluating the use of topical glyceryl trinitrate to facilitate peripheral artery cannulation in neonates. If our pilot randomized controlled trial confirms the benefits of glyceryl trinitrate patches, it will pave the way for large multicenter randomized controlled trials in this field.

Novel nitric oxide donors are coronary vasodilators that also bind to the papain-like protease of SARS-CoV-2

Several investigational nitric oxide donors were originally created to correct vascular endothelial dysfunction in cardiovascular diseases. These 48 compounds contain an urea-like moiety attached to the well-known NO donors isosorbide 2- and 5-mononitrate. CR-0305 and CR-0202 were synthesized and found to be nontoxic in the cell lines HMEC-1, A549/hACE2 and VeroE6. CR-0305 induced vasodilation in human coronary arteries ex vivo. Since NO can also have antiviral properties, a study of drug-protein interactions with SARS-CoV-2 was undertaken using in silico modeling. CR-0305 experimentally outperformed the other compounds, including CR-0202, in binding the catalytic site of SARS-CoV-2 papain-like protease (PLpro). PLpro is a primary target for therapeutic inhibition of SARS-CoV-2 as it mediates viral replication and modulates host innate immune responses. CR-0305 is predicted to sit firmly in the PLpro catalytic pocket as confirmed by molecular dynamics simulations, wherein stability of binding to the catalytic site of PLpro induces a conformational change in the BL2 loop to a more closed conformation as observed previously with GRL0617. Surface plasmon resonance was performed with CR-0305 and CR-0202 to characterize binding affinity to purified SARS-CoV-2 PLpro protein. CR-0305 and CR-0202 also inhibited SARS-CoV-2 infection compared to vehicle as measured by virus N protein staining with a specific antibody in A549-ACE2 and VeroE6 cells at 20 µM. CR-0305 is a coronary vasodilator that appears to bind to the catalytic site of the PLpro of SARS-CoV-2 while targeting delivery of antiviral NO to cells infected by SARS-CoV-2, suggesting multiple indications for future development.

Recent advances on the development of NO-releasing molecules (NORMs) for biomedical applications

Nitric oxide (NO) is an important biological messenger as well as a signaling molecule that participates in a broad range of physiological events and therapeutic applications in biological systems. However, due to its very short half-life in physiological conditions, its therapeutic applications are restricted. Efforts have been made to develop an enormous number of NO-releasing molecules (NORMs) and motifs for NO delivery to the target tissues. These NORMs involve organic nitrate, nitrite, nitro compounds, transition metal nitrosyls, and several nanomaterials. The controlled release of NO from these NORMs to the specific site requires several external stimuli like light, sound, pH, heat, enzyme, etc. Herein, we have provided a comprehensive review of the biochemistry of nitric oxide, recent advancements in NO-releasing materials with the appropriate stimuli of NO release, and their biomedical applications in cancer and other disease control.

Arterial stiffness of the aorta and iliofemoral artery and their responses to nitroglycerin administration in myocardial infarction-prone Watanabe heritable hyperlipidemic rabbits

OBJECTIVES

The role of hypercholesterolemia in arterial stiffness, which usually reflects the progression of atherosclerosis has not been fully investigated. To clarify the meaning of arterial stiffness in hypercholesterolemia, we evaluated arterial stiffness in myocardial infarction-prone Watanabe heritable hyperlipidemic (WHHLMI) rabbits by using new arterial stiffness indices of the aorta and common iliac to femoral artery. The new arterial stiffness indices of both arteries were determined by the application of the theory of cardio-ankle vascular index (CAVI) to the aorta (aBeta) and ilio-femoral artery (ifBeta). Furthermore, the responses of both indices to nitroglycerin (NTG) administration were compared between WHHHMI and normal rabbits.

DESIGN AND METHODS

aBeta and ifBeta of WHHLMI and normal rabbits were measured under anesthesia. Pulse wave velocity in the whole aorta (aPWV) and ilio-femoral artery (ifPWV), blood pressure, and other parameters were measured before and after administration of NTG (50-120 μg/kg/min) every 1 for 5 min.

RESULTS

Atherosclerotic lesions were observed in the aorta, but a little in the ilio-femoral artery in WHHLMI rabbits. Compared with normal rabbits, aBeta was significantly higher, but ifBeta was lower in WHHLMI rabbits. When NTG was administered, ifBeta decreased significantly in both groups; however, aBeta increased in normal rabbits, but remained unchanged in WHHIMI rabbits.

CONCLUSION

These findings suggested that hereditary hypercholesterolemia in rabbits did not uniformly enhance arterial stiffness in elastic artery and muscular artery. The responses to NTG were also different between two arteries. The mechanism of these different responses needs further studies.

Investigating the multitarget pharmacological mechanism of Rhodiola wallichiana var. cholaensis acting on angina pectoris using combined network pharmacology and molecular docking

Background

Rhodiola wallichiana var. cholaensis (RW) is one of the traditional Chinese medicinal materials, which is used to treat angina pectoris (AP). However, the possible underlying mechanisms remains unclear. The aim of this study was to explore RW in the treatment of AP and to identify the potential mechanism of the core compounds.

Methods

In this study, systematic and comprehensive network pharmacology and molecular docking were used for the first time to explore the potential pharmacological mechanisms of RW on AP. First, the relative compounds were obtained by mining the literature, and potential targets of these compounds using target prediction were collected. We then built the AP target database using the DigSee and GeneCards databases. Based on the data, overlapping targets and hub genes were identified with Maximal Clique Centrality (MCC) algorithm in Cytoscape, cytoHubba. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses and protein-protein interaction (PPI) analysis were performed to screen the hub targets by topology. Molecular docking was utilized to investigate the receptor-ligand interactions on Autodock Vina and visualized in PyMOL.

Results

A total of 218 known RW therapeutic targets were selected. Systematic analysis identified nine hub targets (VEGFA, GAPDH, TP53, AKT1, CASP3, STAT3, TNF, MAPK1 and JUN) mainly involved in the complex treatment effects associated with the protection of the vascular endothelium, as well as the regulation of glucose metabolism, cellular processes, inflammatory responses, and cellular signal transduction. Molecular docking indicated that the core compounds had good affinity with the core targets.

Conclusions

The results of this study preliminarily identify the potential targets and signaling pathways of RW in AP therapy and lay a promising foundation for further experimental studies and clinical trials.

Regulatory effects of curcumin on nitric oxide signaling in the cardiovascular system

The continuously rising prevalence of cardiovascular disease (CVD) globally substantially impacts the economic growth of developing countries. Indeed, one of the leading causes of death worldwide is unfavorable cardiovascular events. Reduced nitric oxide (NO) generation is the pathogenic foundation of endothelial dysfunction, which is regarded as the first stage in the development of a number of CVDs. Nitric oxide exerts an array of biological effects, including vasodilation, the suppression of vascular smooth muscle cell proliferation and the functional control of cardiac cells. Numerous treatment strategies aim to increase NO synthesis or upregulate downstream NO signaling pathways. The major component of Curcuma longa, curcumin, has long been utilized in traditional medicine to treat various illnesses, especially CVDs. Curcumin improves CV function as well as having important pleiotropic effects, such as anti-inflammatory and antioxidant, through its ability to increase the bioavailability of NO and to positively impact NO-related signaling pathways. In this review, we discuss the scientific literature relating to curcumin's positive effects on NO signaling and vascular endothelial function.

Regulation of headache response and transcriptomic network by the trigeminal ganglion clock

OBJECTIVE

To characterize the circadian features of the trigeminal ganglion in a mouse model of headache.

BACKGROUND

Several headache disorders, such as migraine and cluster headache, are known to exhibit distinct circadian rhythms of attacks. The circadian basis for these rhythmic pain responses, however, remains poorly understood.

METHODS

We examined trigeminal ganglion ex vivo and single-cell cultures from Per2::LucSV reporter mice and performed immunohistochemistry. Circadian behavior and transcriptomics were investigated using a novel combination of trigeminovascular and circadian models: a nitroglycerin mouse headache model with mechanical thresholds measured every 6 h, and trigeminal ganglion RNA sequencing measured every 4 h for 24 h. Finally, we performed pharmacogenomic analysis of gene targets for migraine, cluster headache, and trigeminal neuralgia treatments as well as trigeminal ganglion neuropeptides; this information was cross-referenced with our cycling genes from RNA sequencing data to identify potential targets for chronotherapy.

RESULTS

The trigeminal ganglion demonstrates strong circadian rhythms in both ex vivo and single-cell cultures, with core circadian proteins found in both neuronal and non-neuronal cells. Using our novel behavioral model, we showed that nitroglycerin-treated mice display circadian rhythms of pain sensitivity which were abolished in arrhythmic Per1/2 double knockout mice. Furthermore, RNA-sequencing analysis of the trigeminal ganglion revealed 466 genes that displayed circadian oscillations in the control group, including core clock genes and clock-regulated pain neurotransmitters. In the nitroglycerin group, we observed a profound circadian reprogramming of gene expression, as 331 of circadian genes in the control group lost rhythm and another 584 genes gained rhythm. Finally, pharmacogenetics analysis identified 10 genes in our trigeminal ganglion circadian transcriptome that encode target proteins of current medications used to treat migraine, cluster headache, or trigeminal neuralgia.

CONCLUSION

Our study unveiled robust circadian rhythms in the trigeminal ganglion at the behavioral, transcriptomic, and pharmacogenetic levels. These results support a fundamental role of the clock in pain pathophysiology.

PLAIN LANGUAGE SUMMARY

Several headache diseases, such as migraine and cluster headache, have headaches that occur at the same time each day. We learned that the trigeminal ganglion, an important pain structure in several headache diseases, has a 24-hour cycle that might be related to this daily cycle of headaches. Our genetic analysis suggests that some medications may be more effective in treating migraine and cluster headache when taken at specific times of the day.

The biological role and future therapeutic uses of nitric oxide in extracorporeal membrane oxygenation, a narrative review

BACKGROUND

Nitric oxide (NO) is a gas naturally produced by the human body that plays an important physiological role. Specifically, it binds guanylyl cyclase to induce smooth muscle relaxation. NO's other protective functions have been well documented, particularly its protective endothelial functions, effects on decreasing pulmonary vascular resistance, antiplatelet, and anticoagulation properties. The use of nitric oxide donors as vasodilators has been known since 1876. Inhaled nitric oxide has been used as a pulmonary vasodilator and to improve ventilation perfusion matching since the 1990s. It is currently approved by the United States Food and Drug Administration for neonates with hypoxic respiratory failure, however, it is used off-label for acute respiratory distress syndrome, acute bronchiolitis, and COVID-19.

PURPOSE

In this article we review the currently understood biological action and therapeutic uses of NO through nitric oxide donors such as inhaled nitric oxide. We will then explore recent studies describing use of NO in cardiopulmonary bypass and extracorporeal membrane oxygenation and speculate on NO's future uses.

Quantification of Nitric Oxide in Single Cells Using the Single-Probe Mass Spectrometry Technique

Nitric oxide (NO) is a small molecule that plays important roles in biological systems and human diseases. The abundance of intracellular NO is tightly related to numerous biological processes. Due to cell heterogeneity, the intracellular NO amounts significantly vary from cell to cell, and therefore, any meaningful studies need to be conducted at the single-cell level. However, measuring NO in single cells is very challenging, primarily due to the extremely small size of single cells and reactive nature of NO. In the current studies, the quantitative reaction between NO and amlodipine, a compound containing the Hantzsch ester group, was performed in live cells. The product dehydro amlodipine was then detected by the Single-probe single-cell mass spectrometry technique to quantify NO in single cells. The experimental results indicated heterogeneous distributions of intracellular NO amounts in single cells with the existence of subpopulations.

p-Nitrobenzoate production from glucose by utilizing p-aminobenzoate N-oxygenase: AurF

Nitroaromatic compounds are widely used in industry, but their production is associated with issues such as the hazardousness of the process and low regioselectivity. Here, we successfully demonstrated the production of p-nitrobenzoate (PNBA) from glucose by constructing p-aminobenzoate N-oxygenase AurF-expressing E. coli. We generated this strain, which we named PN-1 by disrupting four genes involved in PNBA degradation: nfsA, nfsB, nemA, and azoR. We then expressed AurF from Streptomyces thioluteus in this strain, which resulted in the production of 945 mg/L PNBA in the presence of 1 g/L p-aminobenzoate. Direct production of PNBA from glucose was achieved by co-expressing the pabA, pabB, and pabC, as well as aurF, resulting in the production of 393 mg/L PNBA from 20 g/L glucose. To improve the PNBA titer, we disrupted genes involved in competing pathways: pheA, tyrA, trpE, pykA, and pykF. The resultant strain PN-4Ap produced 975 mg/L PNBA after 72 h of cultivation. These results highlight the potential of using microorganisms to produce other nitroaromatic compounds.

The effect of vitamin C on nitroglycerin-mediated vasodilation in individuals with and without the aldehyde dehydrogenase 2 polymorphism

AIMS

To mediate its pharmacodynamic effects, glyceryl trinitrate (GTN) requires bioactivation, by which it releases nitric oxide or a nitric oxide moiety. The exact mechanism of GTN bioactivation remains uncertain. Mitochondrial aldehyde dehydrogenase (ALDH-2) has been proposed as the primary enzyme responsible for this bioactivation process. Evidence for the importance of ALDH-2 in GTN bioactivation has been inconsistent, particularly in human models. An alternative hypothesis suggests that decreased ALDH-2 activity leads to accumulation of reactive cytotoxic aldehydes, which either inhibit the vasoactive product(s) of GTN or impair other enzymatic pathways involved in the bioactivation of GTN. We investigated the effect of supplemental vitamin C on vascular responses to GTN in healthy volunteers of East Asian descent, of whom 12 with and 12 without the ALDH-2 polymorphism participated.

METHODS

Subjects underwent 2 sequential brachial artery infusions of GTN at rates of 5, 11 and 22 nmol/min, separated by a 30-min washout period. The GTN infusions were carried out in the presence and absence of vitamin C using a randomized, crossover design. Venous occlusion plethysmography was used to measure forearm blood flow responses to GTN.

RESULTS

Compared to subjects with functional ALDH-2, the variant group exhibited blunted hemodynamic responses to intra-arterial GTN infusions, although this reduction in response was not statically significant. Contrary to our hypothesis, vitamin C had an inhibitory effect on GTN mediated vasodilation as compared to GTN during saline in both groups.

CONCLUSION

We conclude that vitamin C did not augment the acute vascular response to GTN in those with the ALDH-2 polymorphism.

Targeting endothelial permeability in the EPR effect

The characteristics of the primary tumor blood vessels and the tumor microenvironment drive the enhanced permeability and retention (EPR) effect, which confers an advantage towards enhanced delivery of anti-cancer nanomedicine and has shown beneficial effects in preclinical models. Increased vascular permeability is a landmark feature of the tumor vessels and an important driver of the EPR. The main focus of this review is the endothelial regulation of vascular permeability. We discuss current challenges of targeting vascular permeability towards clinical translation and summarize the structural components and mechanisms of endothelial permeability, the principal mediators and signaling players, the targeted approaches that have been used and their outcomes to date. We also critically discuss the effects of the tumor-infiltrating immune cells, their interplay with the tumor vessels and the impact of immune responses on nanomedicine delivery, the impact of anti-angiogenic and tumor-stroma targeting approaches, and desirable nanoparticle design approaches for greater translational benefit.

Oral Nicorandil effectively attenuates the incidence of contrast-induced nephropathy in patients undergoing cardiac catheterization: a randomized, controlled, open-label clinical trial

PURPOSE

The contrast-induced nephropathy (CIN) rate is increasing globally and can increase the rate of mortality and long-term problems. This study aims to determine the effect of Nicorandil on preventing CIN among patients undergoing cardiac catheterization.

METHODS

In a controlled randomized open-labeled clinical trial, all included patients undergoing cardiac catheterization due to coronary problems and possessing at least two risk factors of contrast nephropathy were divided into two groups of intervention and control. The intervention group received oral Nicorandil and normal saline, while the control group was treated with intravenous normal saline. Serum creatinine was measured before and 48 h after the procedure, and patients were assessed regarding CIN.

RESULTS

In this study, 172 patients entered each group; 41.86% and 45.34% were male in the control and Nicorandil groups. We showed that the incidence of CIN was meaningfully lower in the Nicorandil group (12, 7%) than in the control group (34, 19.8%, P = 0.001). Additionally, the incidence of CIN was notably lower in the female patients in the Nicorandil (85.7%) than in the control group (14.3%, P = 0.001); however, these numbers were not significantly different among men (64.0% and 36.0%, respectively, P = 0.850). After the injection of the contrast agent, the serum levels of blood urea nitrogen (P = 0.248), creatinine (P = 0.081), and glomerular filtration rate (P = 0.386) showed no significant differences between the control and Nicorandil groups. Multivariate regression analysis showed that Nicorandil significantly lowered the odds of CIN [odds ratio (OR) = 0.299, 95% confidence interval (CI) 0.149-0.602; P = 0.001] after adjustment for baseline creatinine (OR = 1.404, 95% CI 0.431-4.572; P = 0.574).

CONCLUSION

Our results indicate that pre-procedural treatment with Nicorandil may be effective against CIN in contrast to agent-exposed patients.

A prospective double-blinded randomized study on drug-eluting stent implantation into nitrate-induced maximally dilated vessels in patients with coronary artery disease

BACKGROUND

Percutaneous coronary intervention (PCI) has been developed using drug-eluting stents (DES); however, stent implantation is associated with concerns of stent thrombosis and target vessel revascularization (TVR). The stent diameter is a critical factor in TVR and clinical events. The nitrate administration in coronary angiography can dilate the reference vessel diameter, enabling accurate vessel size measurement and optimal stent implantation support. This study was designed to evaluate the effect of stent implantation in the maximally dilated coronary artery in patients with coronary artery disease (CAD).

METHODS

This prospective double-blinded randomized (1:1) study is designed to compare the efficacy and safety between DES implantation into the nitrate-induced maximally dilated vessels and conventional DES implantation in patients with CAD. A total of 400 patients who underwent PCI with a sirolimus-eluting stent will be enrolled. The primary endpoint is the mean diameter of the deployed stents. Secondary endpoints include cardiac death, myocardial infarction, stent thrombosis, or ischemia-driven TVR 1 year after the procedure.

DISCUSSION

This study will be the first randomized controlled trial to evaluate the effect of DES implantation on nitrate-induced maximally dilated vessels in patients with CAD.

TRIAL REGISTRATION

The trial was registered on 18 June 2021 as Effect of Ultimaster Stents Treated to the Most Dilated Coronary Vessels (ClinicalTrials.gov Identifier: NCT04931784).

Nitric Oxide Prevents Glioblastoma Stem Cells' Expansion and Induces Temozolomide Sensitization

Glioblastoma multiforme (GBM) has high mortality and recurrence rates. Malignancy resilience is ascribed to Glioblastoma Stem Cells (GSCs), which are resistant to Temozolomide (TMZ), the gold standard for GBM post-surgical treatment. However, Nitric Oxide (NO) has demonstrated anti-cancer efficacy in GBM cells, but its potential impact on GSCs remains unexplored. Accordingly, we investigated the effects of NO, both alone and in combination with TMZ, on patient-derived GSCs. Experimentally selected concentrations of diethylenetriamine/NO adduct and TMZ were used through a time course up to 21 days of treatment, to evaluate GSC proliferation and death, functional recovery, and apoptosis. Immunofluorescence and Western blot analyses revealed treatment-induced effects in cell cycle and DNA damage occurrence and repair. Our results showed that NO impairs self-renewal, disrupts cell-cycle progression, and expands the quiescent cells' population. Consistently, NO triggered a significant but tolerated level of DNA damage, but not apoptosis. Interestingly, NO/TMZ cotreatment further inhibited cell cycle progression, augmented G0 cells, induced cell death, but also enhanced DNA damage repair activity. These findings suggest that, although NO administration does not eliminate GSCs, it stunts their proliferation, and makes cells susceptible to TMZ. The resulting cytostatic effect may potentially allow long-term control over the GSCs' subpopulation.

Dose-response study of prophylactic nitroglycerin for prevention of pituitrin-induced hypertension during laparoscopic myomectomy: a prospective, randomized study

Objective

To determine the dose-response of nitroglycerin in preventing pituitrin-induced hypertension in patients undergoing laparoscopic myomectomy.

Methods

Hundred patients scheduled for elective laparoscopic myomectomy were randomly allocated into one of five groups (n = 20) to receive intravenous bolus of prophylactic nitroglycerin at 0, 50, 75, 100, and 125 μg one minute following administration of 3 IU of pituitrin into the myometrium. The patients were monitored for pituitrin-induced hypertension with the primary outcome to determine the effective dose of prophylactic nitroglycerin, defined as complete prevention of pituitrin-induced hypertension during the study period. Probit analysis was used to calculate the median effective dose (ED₅₀) and 95% effective dose (ED₉₅) of prophylactic nitroglycerin.

Results

Hypertension occurred in 19/20, 10/20, 8/20, 2/20, and 1/20 in patients who received 0, 50, 75, 100, and 125 ug of prophylactic nitroglycerin, respectively. The calculated ED₅₀ and ED₉₅ of nitroglycerin for preventing hypertension were 54 μg (95%CI: 35~66 μg) and 136 μg (95%CI: 105~289 μg).

Conclusion

A prophylactic bolus of nitroglycerin administered immediately following injection of pituitrin into the myometrium during laparoscopic myomectomy effectively prevented pituitrin-induced hypertension, with the ED₅₀ and ED₉₅ of 54 μg and 136 μg, respectively. This information would be useful for clinical practice.

Clinical trial registration

www.chictr.org.cn, Identifier ChiCTR2200062282.

NIR-II Absorbing Conjugated Polymer Nanotheranostics for Thermal Initiated NO Enhanced Photothermal Therapy

Photothermal therapy (PTT) has received constant attention as a promising cancer treatment. However, PTT-induced inflammation can limit its effectiveness. To address this shortcoming, we developed second near-infrared (NIR-II) light-activated nanotheranostics (CPNPBs), which include a thermosensitive nitric oxide (NO) donor (BNN6) to enhance PTT. Under a 1064 nm laser irradiation, the conjugated polymer in CPNPBs serves as a photothermal agent for photothermal conversion, and the generated heat triggers the decomposition of BNN6 to release NO. The combination of hyperthermia and NO generation under single NIR-II laser irradiation allows enhanced thermal ablation of tumors. Consequently, CPNPBs can be exploited as potential candidates for NO-enhanced PTT, holding great promise for their clinical translational development.

Physical Activity and Mortality in Patients with Coronary Artery Disease

PURPOSE OF REVIEW

Coronary artery disease (CAD) accounts for half of heart-related mortalities. Secondary prevention measures are aimed at enhancing the probability of survival in acute and chronic heart diseases. Physical activity (PA) has been shown to effectively reduce all-cause and cardiovascular (CV) mortality rates. This article reviews the relationship between PA and mortality in patients with CAD. Additionally, we discuss the process of vascular changes that contributes to survival benefits in physically active CAD patients, along with exercise dosing and guideline recommendations.

RECENT FINDINGS

Recent studies have shown that physical inactivity poses a modifiable risk factor that impedes favorable vasculature remodeling, unlike active individuals. Recent meta-analyses provide strong evidence of the multifaceted advantages of PA in lowering mortality rates in patients with CAD, as opposed to physically inactive participants. In summary, substantial evidence indicates that PA is significantly associated with reduction in all-cause and CV mortality in CAD patients, with a dose-response relationship.

Nitroglycerin improves the visibility of fibula-free flap perforators on computed tomography angiography in patients with oral or maxillofacial lesion

PURPOSE

To investigate the improvement of image quality and visualization of fibula-free flap (FFF) perforators on computed tomography angiography (CTA) after administration of sublingual nitroglycerin (NTG) tablets.

METHODS

A total of 60 patients with oral or maxillofacial lesions before CTA of the lower extremity were randomly divided into two groups (NTG group and non-NTG group). The signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR), overall image quality and grading of vessels were evaluated and compared. The lumen diameters of the major arteries and the proximal and distal peroneal perforators were measured. The number of visible perforators in muscular clearance and muscular layer was also counted and compared between the two groups.

RESULTS

The CNR of posterior tibial artery and overall image quality of CTA images in the NTG group was significantly higher than that in the non-NTG group (p < 0.05), although the SNR and CNR of other arteries did not show significant differences (p > 0.05). The lumen diameters of the peroneal artery and its perforators, anterior tibial artery, and posterior tibial artery were significantly larger in the NTG group (p < 0.001), while no significant difference prevailed in the diameter of the popliteal artery between the two groups (p = 0.298). Compared with the non-NTG group, a significant increase in the number of visible perforators was noted in the NTG group (p < 0.001).

CONCLUSIONS

The administration of sublingual NTG in CTA of the lower extremity can improve the image quality and visualization of perforators, which aids to surgeons select the optimum FFF.

A comparative study between angiotensin receptor neprilysin inhibitor (thiorphan/irbesartan) with each of nitrate and carvedilol in a rat model of myocardial ischemic reperfusion injury

The combined angiotensin receptor neprilysin inhibitor is a promising cardioprotective pharmacological agent. This study investigated the beneficial effects of thiorphan (TH)/irbesartan (IRB), in myocardial ischemia-reperfusion (IR) injury, compared to each of nitroglycerin and carvedilol. Male Wistar rats were divided into five groups (10 rats/group): Sham, untreated I/R, TH/IRB + IR (0.1/10 mg/kg), nitroglycerin + IR (0.2 mg/kg), and carvedilol + IR (10 mg/kg). Mean arterial blood pressure, cardiac functions and arrhythmia incidence, duration and score were assessed. Cardiac levels of creatine kinase-MB (CK-MB), oxidative stress, endothelin-1, ATP, Na⁺ /K⁺ ATPase pump activity and mitochondria complexes activities were measured. Histopathological examination, Bcl/Bax immunohistochemistry studies and electron microscopy examination of left ventricle were performed. TH/IRB preserved the cardiac functions and mitochondrial complexes activities, mitigated cardiac damage, reduced oxidative stress and arrhythmia severity, improved the histopathological changes and decreased cardiac apoptosis. TH/IRB showed a comparable effect to each of nitroglycerin and carvedilol in alleviating the IR injury consequences. TH/IRB showed significant preservation of mitochondrial complexes activity I and II compared to nitroglycerin. TH/IRB significantly increased LVdP/dtmax and decreased oxidative stress, cardiac damage and endothelin-1 along with increasing the ATP content, Na⁺ /K⁺ ATPase pump activity and mitochondrial complexes activity when compared to carvedilol. TH/IRB showed a cardioprotective effect in reducing IR injury that is comparable to each of nitroglycerin and carvedilol that could be explained in part by its ability to preserve mitochondrial function, increase ATP, decrease oxidative stress as well as endothelin 1.

Effect of clevidipine on intracranial pressure in pediatric neurosurgical patients: a single-center retrospective review

OBJECTIVE

Hemodynamic management in pediatric neurosurgical patients is essential for maintaining cerebral perfusion pressure (CPP), avoiding hemorrhage, and preventing secondary neurological injury. Antihypertensive infusions approved for pediatrics are not widely studied in the pediatric neurosurgical population and may have adverse effects on intracranial pressure (ICP), contributing to reduced CPP. Clevidipine is an ultra-rapid-acting intravenous antihypertensive agent used for hemodynamic control in adult surgical patients. In pediatric patients, clevidipine is safe and effective in controlling blood pressure in the perioperative period, although studies evaluating its effect on ICP in neurosurgical patients are lacking. The objective of this research was to evaluate the effect of clevidipine on ICP in pediatric neurosurgical patients.

METHODS

This single-center retrospective study involved patients admitted to the pediatric ICU between January 1, 2017, and December 31, 2020. Patients eligible for inclusion had ICP monitoring devices and received clevidipine infusion for a minimum of 6 hours postoperatively, with at least one ICP measurement pre- and postinfusion. Excluded patients had an elevated preinfusion ICP > 20 mm Hg. The primary outcome was the average change in ICP from preinfusion baseline to hours 6 to < 12, 12 to < 24, and 24 to < 48 of clevidipine infusion. Secondary outcomes included frequency of ICP measurements > 20 mm Hg, CPP measurements < 50 mm Hg, treatment failure defined by a need for concurrent antihypertensive infusion, and frequency of elevated serum triglycerides > 200 mg/dL. Descriptive data were expressed as frequency with percentage or median with interquartile range as appropriate. Analysis of continuous outcome variable data involved Mann-Whitney U-tests with an alpha significance of 0.05.

RESULTS

Data from 47 patients were included in the analysis. The average change in ICP from preinfusion baseline to 48 hours was < 1 mm Hg. Of 3025 total postinfusion ICP measurements in 47 patients, 67 measurements (2.2%) in 13 patients (28%) were > 20 mm Hg. CPP measurements < 50 mm Hg occurred in 16 of 45 patients (36%). Three patients (6.4%) required use of a secondary antihypertensive medication infusion, and 5 of 14 patients (36%) had serum triglycerides > 200 mg/dL.

CONCLUSIONS

Use of clevidipine had minimal effect on ICP. The results of this study suggest that clevidipine is effective at safely maintaining ICP and CPP measurements without detrimental adverse effects in pediatric neurosurgical patients.

In Vitro Drug Repurposing: Focus on Vasodilators

Drug repurposing aims to identify new therapeutic uses for drugs that have already been approved for other conditions. This approach can save time and resources compared to traditional drug development, as the safety and efficacy of the repurposed drug have already been established. In the context of cancer, drug repurposing can lead to the discovery of new treatments that can target specific cancer cell lines and improve patient outcomes. Vasodilators are a class of drugs that have been shown to have the potential to influence various types of cancer. These medications work by relaxing the smooth muscle of blood vessels, increasing blood flow to tumors, and improving the delivery of chemotherapy drugs. Additionally, vasodilators have been found to have antiproliferative and proapoptotic effects on cancer cells, making them a promising target for drug repurposing. Research on vasodilators for cancer treatment has already shown promising results in preclinical and clinical studies. However, additionally research is needed to fully understand the mechanisms of action of vasodilators in cancer and determine the optimal dosing and combination therapy for patients. In this review, we aim to explore the molecular mechanisms of action of vasodilators in cancer cell lines and the current state of research on their repurposing as a treatment option. With the goal of minimizing the effort and resources required for traditional drug development, we hope to shed light on the potential of vasodilators as a viable therapeutic strategy for cancer patients.

Hemodynamic impact of early mobilization in critical patients receiving vasoactive drugs: A prospective cohort study

BACKGROUND

Vasoactive drugs are one of the most common patient-related barriers to early mobilization. Little is known about the hemodynamic effects of early mobilization on patients receiving vasoactive drugs. This study aims to observe and describe the impact of mobilization on the vital signs of critical patients receiving vasoactive drugs as well as the occurrence of adverse events.

METHODS

This is a cohort study performed in an Intensive Care Unit with patients receiving vasoactive drugs. All patients, either mobilized or non-mobilized, had their clinical data such as vital signs [heart rate, respiratory rate, systolic blood pressure, diastolic blood pressure, mean arterial pressure, and oxygen saturation], type and dosage of the vasoactive drug, and respiratory support collected at rest. For mobilized patients, the vital signs were also collected after mobilization, and so was the highest level of mobility achieved and the occurrence of adverse events. The criteria involved in the decision of mobilizing the patients were registered.

RESULTS

53 patients were included in this study and 222 physiotherapy sessions were monitored. In most of the sessions (n = 150, 67.6%), patients were mobilized despite the use of vasoactive drugs. There was a statistically significant increase in heart rate and respiratory rate after mobilization when compared to rest (p<0.05). Only two (1.3%) out of 150 mobilizations presented an adverse event. Most of the time, non-mobilizations were justified by the existence of a clinical contraindication (n = 61, 84.7%).

CONCLUSIONS

The alterations observed in the vital signs of mobilized patients may have reflected physiological adjustments of patients' cardiovascular and respiratory systems to the increase in physical demand imposed by the early mobilization. The adverse events were rare, not serious, and reversed through actions such as a minimal increase of the vasoactive drug dosage.

Enhanced Permeability and Retention Effect as a Ubiquitous and Epoch-Making Phenomenon for the Selective Drug Targeting of Solid Tumors

In 1979, development of the first polymer drug SMANCS [styrene-co-maleic acid (SMA) copolymer conjugated to neocarzinostatin (NCS)] by Maeda and colleagues was a breakthrough in the cancer field. When SMANCS was administered to mice, drug accumulation in tumors was markedly increased compared with accumulation of the parental drug NCS. This momentous result led to discovery of the enhanced permeability and retention effect (EPR effect) in 1986. Later, the EPR effect became known worldwide, especially in nanomedicine, and is still believed to be a universal mechanism for tumor-selective accumulation of nanomedicines. Some research groups recently characterized the EPR effect as a controversial concept and stated that it has not been fully demonstrated in clinical settings, but this erroneous belief is due to non-standard drug design and use of inappropriate tumor models in investigations. Many research groups recently provided solid evidence of the EPR effect in human cancers (e.g., renal and breast), with significant diversity and heterogeneity in various patients. In this review, we focus on the dynamics of the EPR effect and restoring tumor blood flow by using EPR effect enhancers. We also discuss new applications of EPR-based nanomedicine in boron neutron capture therapy and photodynamic therapy for solid tumors.

Angina in 2022: Current Perspectives

Angina is the main symptom of ischemic heart disease; mirroring a mismatch between oxygen supply and demand. Epicardial coronary stenoses are only responsible for nearly half of the patients presenting with angina; whereas in several cases; symptoms may underlie coronary vasomotor disorders; such as microvascular dysfunction or epicardial spasm. Various medications have been proven to improve the prognosis and quality of life; representing the treatment of choice in stable angina and leaving revascularization only in particular coronary anatomies or poorly controlled symptoms despite optimal medical therapy. Antianginal medications aim to reduce the oxygen supply-demand mismatch and are generally effective in improving symptoms; quality of life; effort tolerance and time to ischemia onset and may improve prognosis in selected populations. Since antianginal medications have different mechanisms of action and side effects; their use should be tailored according to patient history and potential drug-drug interactions. Angina with non-obstructed coronary arteries patients should be phenotyped with invasive assessment and treated accordingly. Patients with refractory angina represent a higher-risk population in which some therapeutic options are available to reduce symptoms and improve quality of life; but robust data from large randomized controlled trials are still lacking.

The anesthetic management of a patient undergoing simultaneous open abdominal aortic aneurysm repair and coronary artery bypass grafting: A case report

RATIONALE

Surgery for abdominal aortic aneurysm (AAA) and concomitant severe coronary artery disease (CAD) is usually managed in a staged procedure. The anesthesia for concurrent surgery is rare and complex. In this report, we present an unusual case of undergoing simultaneous open abdominal aortic aneurysm (AAA) repair and coronary artery bypass grafting (CABG).

PATIENT CONCERNS

A 70-year-old male AAA patient with concurrent triple-vessel CAD underwent a simultaneous surgery.

DIAGNOSIS

The patient underwent computed tomography angiography (CTA) and coronary angiography. He was diagnosed with AAA and triple-vessel CAD.

INTERVENTIONS

The patient underwent simultaneous surgery.

OUTCOMES

The patient underwent anesthesia and surgery smoothly and was discharged on the 13th postoperative day.

LESSONS

The anesthetic management of simultaneous open abdominal aortic aneurysm repair and coronary artery bypass grafting is rare and complicated. Reasonable operation and anesthesia protocols, close monitoring and management of hemodynamic changes, and appropriate cell salvage and hemostasis measures are of great significance to increase perioperative safety and reduce the risk of postoperative complications.

Synthesis and Vasorelaxant Activity of Nitrate-Coumarin Derivatives

Due to the need for new chemical entities for cardiovascular diseases, we have synthesized a new series of nitrate-coumarins and evaluated their vasorelaxant activity in contraction-relaxation studies using rat aorta rings precontracted with phenylephrine or by depolarization with a high concentration of potassium chloride. Four of the new compounds were able to relax smooth vascular muscle with a similar profile and potency to glyceryl trinitrate (IC50 =12.73 nM) and sodium nitroprusside (IC50 =4.32 nM). Coumarin-7-yl-methyl nitrate (4), the best compound within the series, was able to relax smooth vascular muscle in the low nanomolar range (IC50 =1.92 nM). The mechanisms of action have been explored, being the activation of sGC and the opening of K+ channels involved. Our studies indicate that the new nitrate derivatives are reversible and not deleterious for aortic rings, suggesting that these compounds have a potential interest for the development of new and highly efficient vasodilator drugs.

Utility of NO and H2S donating platforms in managing COVID-19: Rationale and promise

Viral infections are a continuing global burden on the human population, underscored by the ramifications of the COVID-19 pandemic. Current treatment options and supportive therapies for many viral infections are relatively limited, indicating a need for alternative therapeutic approaches. Virus-induced damage occurs through direct infection of host cells and inflammation-related changes. Severe cases of certain viral infections, including COVID-19, can lead to a hyperinflammatory response termed cytokine storm, resulting in extensive endothelial damage, thrombosis, respiratory failure, and death. Therapies targeting these complications are crucial in addition to antiviral therapies. Nitric oxide and hydrogen sulfide are two endogenous gasotransmitters that have emerged as key signaling molecules with a broad range of antiviral actions in addition to having anti-inflammatory properties and protective functions in the vasculature and respiratory system. The enhancement of endogenous nitric oxide and hydrogen sulfide levels thus holds promise for managing both early-stage and later-stage viral infections, including SARS-CoV-2. Using SARS-CoV-2 as a model for similar viral infections, here we explore the current evidence regarding nitric oxide and hydrogen sulfide's use to limit viral infection, resolve inflammation, and reduce vascular and pulmonary damage.

Local nitroglycerin to facilitate peripheral arterial cannulation in children: systematic review and meta-analysis

BACKGROUND

Neonates and children admitted to intensive care units require peripheral arterial cannulation to monitor their blood pressures and for blood sampling, but many times it is unsuccessful.

OBJECTIVE

To conduct a systematic review and meta-analysis to evaluate the efficacy and safety of local nitroglycerin (NTG) to facilitate peripheral artery cannulation in neonates and children.

REVIEW METHODS

PubMed, EMBASE, CINAHL, Emcare and Cochrane library were searched till August 2021. Grey literature was searched through Mednar. Data were extracted by two reviewers independently using a prespecified form and the risk of bias was assessed. Meta-analysis was conducted using a random-effects model. The I2 statistic was used to quantify statistical heterogeneity. Certainty of evidence was assessed using the criteria of inconsistency, imprecision, indirectness, publication bias and size of effect as per the Grading of Recommendations, Assessment, Development and Evaluations (GRADE) guidelines.

RESULTS

Two randomised controlled trials (RCTs) were included in this meta-analysis (n=153). One was conducted in children 2-8 years of age and the other was in children <2 years. Both trials found increased success rates with the use of local NTG. Pooling of the two studies found that the first-attempt success rate was significantly higher in the NTG group (risk difference: 0.44, 95% CI 0.05 to 0.83; I2=89%). Overall procedure time was significantly lower in the NTG group (mean difference: -100.28 s, 95% CI -136.74 to -63.82; I2=0%). No major complications secondary to the use of NTG were noted. The GRADE of evidence was very low.

CONCLUSION

Local NTG may be useful in facilitating peripheral arterial cannulation in children. Adequately powered RCTs are needed to confirm these findings.

Endothelial and Vascular Smooth Muscle Dysfunction in Hypertension

The development of essential hypertension involves several factors. Vascular dysfunction, characterized by endothelial dysfunction, low-grade inflammation and structural remodeling, plays an important role in the initiation and maintenance of essential hypertension. Although the mechanistic pathways by which essential hypertension develops are poorly understood, several pharmacological classes available on the clinical settings improve blood pressure by interfering in the cardiac output and/or vascular function. This review is divided in two major sections. The first section depicts the major molecular pathways as renin angiotensin aldosterone system (RAAS), endothelin, nitric oxide signalling pathway and oxidative stress in the development of vascular dysfunction. The second section describes the role of some pharmacological classes such as i) RAAS inhibitors, ii) dual angiotensin receptor-neprilysin inhibitors, iii) endothelin-1 receptor antagonists, iv) soluble guanylate cyclase modulators, v) phosphodiesterase type 5 inhibitors and vi) sodium-glucose cotransporter 2 inhibitors in the context of hypertension. Some classes are already approved in the treatment of hypertension, but others are not yet approved. However, due to their potential benefits these classes were included.

Preventive and Therapeutic Effects of Low-Intensity Ultrasound Stimulation on Migraine in Rats

This study sought to systematically evaluate the prophylactic and therapeutic effects of low-intensity transcranial ultrasound stimulation on migraine in rats. We used video recordings to assess the head scratching behavior and laser speckle contrast imaging to record the changes in cerebral blood flow velocity of freely moving rats in a healthy group, migraine group, migraine group with ultrasound prevention, and migraine group with ultrasound therapy. Results demonstrated that (1) head scratching during migraine attacks in rats was accompanied by an decrease in cerebral blood flow; (2) both ultrasound prevention and therapy significantly reduced the number of head scratches but did not reduce the cerebral blood flow velocity; and (3) the number of head scratches in the ultrasound stimulation groups was not affected by the auditory effect. These results reveal that low-intensity ultrasound has the potential to be used clinically in the prevention and therapeutic treatment of migraine.

Increased PDT Efficacy When Associated with Nitroglycerin: A Study on Retinoblastoma Xenografted on Mice

Purposes: The aim of the study was to assess the efficacy of a treatment protocol that combines photodynamic therapy (PDT) and nitroglycerin (NG) on human retinoblastoma tumors xenografted on mice. We aimed to increase the PDT efficiency (in our least treatment-responsive retinoblastoma line) with better PS delivery to the tumor generated by NG, which is known to dilate vessels and enhance the permeability and retention of macromolecules in solid tumors. Methods: In vivo follow-up of the therapeutic effects was performed by sodium MRI, which directly monitors variations in sodium concentrations non-invasively and can be used to track the tumor response to therapy. NG ointment was applied one hour before PDT. The PDT protocol involves double-tumor targeting, i.e., cellular and vascular. The first PS dose was injected followed by a second one, separated by a 3 h interval. The timelapse allowed the PS molecules to penetrate tumor cells. Ten minutes after the second dose, the PS was red-light-activated. Results: In this study, we observed that the PDT effect was enhanced by applying nitroglycerin ointment to the tumor-bearing animal’s skin. PDT initiates the bystander effect on retinoblastomas, and NG increases this effect by increasing the intratumoral concentration of PS, which induces a higher production of ROS in the illuminated region and thus increases the propagation of the cell death signal deeper into the tumor (bystander effect).

Nitroglycerin as a model of migraine: Clinical and preclinical review

Migraine stands as one of the most disabling neurological conditions worldwide. It is a disorder of great challenge to study given its heterogeneous representation, cyclic nature, and complexity of neural networks involved. Despite this, clinical and preclinical research has greatly benefitted from the use of the nitric oxide donor, nitroglycerin (NTG), to model this disorder, dissect underlying mechanisms, and to facilitate the development and screening of effective therapeutics. NTG is capable of triggering a migraine attack, only in migraineurs or patients with a history of migraine and inducing migraine-like phenotypes in rodent models. It is however unclear to what extent NTG and NO, as its breakdown product, is a determinant factor in the underlying pathophysiology of migraine, and importantly, whether it really does facilitate the translation from the bench to the bedside, and vice-versa. This review provides an insight into the evidence supporting the strengths of this model, as well as its limitations, and shines a light into the possible role of NO-related mechanisms in altered molecular signalling pathways.

Nitroglycerin Use in the Emergency Department: Current Perspectives

Nitroglycerin, a fast-acting vasodilator, is commonly used as a first-line agent for angina in the emergency department and to manage chest pain due to acute coronary syndromes. It is also a treatment option for other disease states such as acute heart failure, pulmonary edema, and aortic dissection. Nitroglycerin is converted to nitric oxide, a potent vasodilator, in the body, leading to venodilation at lower dosages and arteriodilation at higher dosages that results in both preload and afterload reduction, respectively. Although nitroglycerin has historically been administered as a sublingual tablet and/or spray, it is often given intravenously in the emergency department as this enables titration to effect with predictable pharmacokinetics. In this review article, we outline the indications, mechanism of action, contraindications, and adverse effects of nitroglycerin as well as review relevant literature and make general recommendations regarding the use of nitroglycerin in the emergency department.

The Diverse Biological Activity of Recently Synthesized Nitro Compounds

The search for new and efficient pharmaceuticals is a constant struggle for medicinal chemists. New substances are needed in order to treat different pathologies affecting the health of humans and animals, and these new compounds should be safe, effective and have the fewest side effects possible. Some functional groups are known for having biological activity; in this matter, the nitro group (NO₂) is an efficient scaffold when synthesizing new bioactive molecules. Nitro compounds display a wide spectrum of activities that include antineoplastic, antibiotic, antihypertensive, antiparasitic, tranquilizers and even herbicides, among many others. Most nitro molecules exhibit antimicrobial activity, and several of the compounds mentioned in this review may be further studied as lead compounds for the treatment of H. pylori, P. aeruginosa, M. tuberculosis and S. mutans infections, among others. The NO₂ moiety triggers redox reactions within cells causing toxicity and the posterior death of microorganisms, not only bacteria but also multicellular organisms such as parasites. The same effect may be present in humans as well, so the nitro groups can be considered both a pharmacophore and a toxicophore at the same time. The role of the nitro group itself also has a deep effect on the polarity and electronic properties of the resulting molecules, and hence favors interactions with some amino acids in proteins. For these reasons, it is fundamental to analyze the recently synthesized nitro molecules that show any potential activity in order to develop new pharmacological treatments that enhance human health.

Chronic snus use in healthy males alters endothelial function and increases arterial stiffness

Background

Snus usage is commonly touted as a safer alternative to cigarette smoking. However, recent studies have demonstrated possible adverse cardiovascular effects in chronic snus users. The present study evaluates the effects of chronic snus use on vascular function by assessing central arterial stiffness and endothelial vasodilatory function in healthy chronic snus users as compared to matched non-users.

Methods and results

Fifty healthy males (24 snus users, 26 age-matched controls) with a mean age of 44 years were included in the study. Arterial stiffness was assessed employing both pulse wave velocity and pulse wave analysis. Endothelial vasodilatory function was measured by venous occlusion plethysmography, utilizing intra-arterial administration of acetylcholine, glyceryl trinitrate and bradykinin to further gauge endothelium-dependent and -independent vasodilatory function. Arterial stiffness was significantly higher in chronic snus users as compared to controls: pulse wave velocity [m/s]: 6.6±0.8 vs 7.1±0.9 resp. (p = 0.026), augmentation index corrected for heart rate [%]: 0.1±13.2 vs 7.3±7.8 resp. (p = 0.023). Endothelial independent vasodilation, i.e. the reaction to glyceryl trinitrate, was significantly lower in snus users as measured by venous occlusion plethysmography.

Conclusions

The results of this study show an increased arterial stiffness and an underlying endothelial dysfunction in daily snus users as compared to matched non-tobacco controls. These findings indicate that long-term use of snus may alter the function of the endothelium and therefore reinforces the assertion that chronic snus use is correlated to an increased risk of development of cardiovascular disease.

Vericiguat in Combination with Short-Acting Nitroglycerin in Patients With Chronic Coronary Syndromes: The Randomized, Phase Ib, VENICE Study

Vericiguat is a soluble guanylate cyclase stimulator indicated to reduce the risk of cardiovascular death and heart failure (HF) hospitalization in adults with symptomatic chronic HF and ejection fraction less than 45%. Guidelines recommend short‐acting nitrates, such as sublingual nitroglycerin, for the treatment of acute angina pectoris in patients with chronic coronary syndromes (CCSs), common comorbidities in HF. We evaluated safety, tolerability, and the pharmacodynamic interaction between vericiguat and nitroglycerin, coadministered in patients with CCSs. In this phase Ib, double‐blind, randomized, multicenter study, 36 patients with CCSs received either vericiguat 2.5 mg (up‐titrated every 2 weeks to 5 mg and 10 mg) or placebo. Patients also received nitroglycerin (0.4 mg sublingual). In total, 31 patients completed the study (vericiguat + nitroglycerin, n = 21; placebo + nitroglycerin, n = 10). There was no increase in treatment‐emergent adverse events (TEAEs) with vericiguat + nitroglycerin vs. placebo + nitroglycerin; three patients discontinued due to TEAEs (vericiguat + nitroglycerin, n = 1; placebo + nitroglycerin, n = 2). Decreases in mean blood pressure (BP; 6–10 mmHg systolic BP (SBP); 4–6 mmHg diastolic BP (DBP)) were independent of vericiguat exposure and occurred to a similar extent at trough and peak concentrations with all vericiguat doses and placebo. Coadministration of vericiguat with nitroglycerin in patients with CCSs was well tolerated, and the combination is unlikely to cause significant adverse effects beyond those known for nitroglycerin.

Sex-related differences in endothelium-dependent vasodilation of human gingiva

Background

Sex hormones influence circulation, periodontitis, and wound healing. The aim of the study was to compare the endothelium-dependent and independent vasodilation in human gingiva in men and women.

Methods

Gingival blood flow was evaluated in twelve male and twelve female subjects with healthy gingiva and no systemic conditions after acetylcholine or nitric oxide donor (NitroPOHL). Agonists were administered into the gingival sulcus at the right secondary incisor (test site). Regional gingival blood flow (GBF) was imaged by Laser Speckle Contrast Imager from the marginal gingiva to the mucogingival junction in four consecutive regions (coronal, midway1, midway2 and apical). Blood flow was expressed in Laser Speckle Perfusion Unit (LSPU). The absolute maximal blood flow change (Dmax), the area under the blood flow curve (AUC), and the time to peak (TTP) were calculated.

Results

Males had higher baseline GBF than females (257 ± 18.2 vs. 225 ± 18.8 LSPU, p < 0.001). Acetylcholine and NitroPOHL significantly increased the GBF in all test regions. The Dmax after the acetylcholine was reduced apically compared to the coronal (90 ± 13 LSPU vs. 117 ± 7 LSPU, p < 0.01), but it was similar after NitroPOHL (78 ± 9 LSPU vs. 86 ± 6 LSPU, p = 0.398) in both sexes. The Dmax and AUC were higher, and the TTP was smaller in men in most regions after acetylcholine but not after NitroPOHL.

Conclusion

In the human gingiva, the endothelium-independent vasodilation propagates without attenuation in the line of the vascular supply in both sexes. At the same time, the endothelium-dependent ascending vasodilation attenuates similarly in men and women. However, men had more pronounced endothelium-dependent vasodilation than women. Therefore, it might contribute to the increased severity of periodontal disease in men.

Trial registration

The study was registered with ClinicalTrials.gov on 09.06.2021 (NCT04918563).

A physiologically relevant role for NO stored in vascular smooth muscle cells: A novel theory of vascular NO signaling

S-nitrosothiols (SNO), dinitrosyl iron complexes (DNIC), and nitroglycerine (NTG) dilate vessels via activation of soluble guanylyl cyclase (sGC) in vascular smooth muscle cells. Although these compounds are often considered to be nitric oxide (NO) donors, attempts to ascribe their vasodilatory activity to NO-donating properties have failed. Even more puzzling, many of these compounds have vasodilatory potency comparable to or even greater than that of NO itself, despite low membrane permeability. This raises the question: How do these NO adducts activate cytosolic sGC when their NO moiety is still outside the cell? In this review, we classify these compounds as ‘nitrodilators’, defined by their potent NO-mimetic vasoactivities despite not releasing requisite amounts of free NO. We propose that nitrodilators activate sGC via a preformed nitrodilator-activated NO store (NANOS) found within the vascular smooth muscle cell. We reinterpret vascular NO handling in the framework of this NANOS paradigm, and describe the knowledge gaps and perspectives of this novel model.

Nitric oxide-releasing biomaterials for promoting wound healing in impaired diabetic wounds: State of the art and recent trends

Impaired diabetic wounds are serious pathophysiological complications associated with persistent microbial infections including failure in the closure of wounds, and the cause of a high frequency of lower limb amputations. The healing of diabetic wounds is attenuated due to the lack of secretion of growth factors, prolonged inflammation, and/or inhibition of angiogenic activity. Diabetic wound healing can be enhanced by supplying nitric oxide (NO) endogenously or exogenously. NO produced inside the cells by endothelial nitric oxide synthase (eNOS) naturally aids wound healing through its beneficial vasculogenic effects. However, during hyperglycemia, the activity of eNOS is affected, and thus there becomes an utmost need for the topical supply of NO from exogenous sources. Thus, NO-donors that can release NO are loaded into wound healing patches or wound coverage matrices to treat diabetic wounds. The burst release of NO from its donors is prevented by encapsulating them in polymeric hydrogels or nanoparticles for supplying NO for an extended duration of time to the diabetic wounds. In this article, we review the etiology of diabetic wounds, wound healing strategies, and the role of NO in the wound healing process. We further discuss the challenges faced in translating NO-donors as a clinically viable nanomedicine strategy for the treatment of diabetic wounds with a focus on the use of biomaterials for the encapsulation and in vivo controlled delivery of NO-donors.

Strategies to improve the EPR effect: A mechanistic perspective and clinical translation

Many efforts have been made to achieve targeted delivery of anticancer drugs to enhance their efficacy and to reduce their adverse effects. These efforts include the development of nanomedicines as they can selectively penetrate through tumor blood vessels through the enhanced permeability and retention (EPR) effect. The EPR effect was first proposed by Maeda and co-workers in 1986, and since then various types of nanoparticles have been developed to take advantage of the phenomenon with regards to drug delivery. However, the EPR effect has been found to be highly variable and thus unreliable due to the complex tumor microenvironment. Various physical and pharmacological strategies have been explored to overcome this challenge. Here, we review key advances and emerging concepts of such EPR-enhancing strategies. Furthermore, we analyze 723 clinical trials of nanoparticles with EPR enhancers and discuss their clinical translation.