Carbon monoxide: present and future indications for a medical gas

Baseline correction for the infrared spectra of exhaled breath

Infrared spectroscopy appears to be a promising analytical method for the metabolic analysis of breath. However, due to the presence of trace amounts in exhaled breath, the absorption strength of the metabolites remains extremely low. In such low detection limits, the nonlinear detection sensitivity of the infrared detector and electronic noise strongly modify the baseline of the acquired infrared spectra of breath. Fitting the reference molecular spectra with the baseline-modified spectral features of breath metabolites does not provide accurate identification. Therefore, baseline correction of the acquired infrared spectra of breath is the primary requirement for the success of breath-based infrared diagnosis. A selective spectral region-based, simple baseline correction method is proposed for the infrared spectroscopy of breath.

Therapeutic Use of Carbon Monoxide in Ex-Vivo Lung Perfusion in Donor With Prolonged Cold Ischemia

INTRODUCTION

Carbon monoxide (CO) has been shown to exert protective effects in multiple organs following ischemic injury, including the lung. The purpose of this study was to examine the effects of CO administration during ex vivo lung perfusion (EVLP) on lung grafts exposed to prolonged cold ischemia.

METHODS

Ten porcine lungs were subjected to 18 h of cold ischemia followed by 6 h of EVLP. Lungs were randomized to EVLP alone (control, n = 5) or delivery of 500 ppm of CO during the 1st hour of EVLP (treatment, n = 5). Following EVLP, the left lungs were transplanted and reperfused for 4 h.

RESULTS

At the end of EVLP, pulmonary vascular resistance (P = 0.007) and wet to dry lung weight ratios (P = 0.027) were significantly reduced in CO treated lungs. Posttransplant, lung graft PaO2/FiO2 (P = 0.032) and compliance (P = 0.024) were significantly higher and peak airway pressure (P = 0.032) and wet to dry ratios (P = 0.003) were significantly lower in CO treated lungs. Interleukin-6 was significantly reduced in plasma during reperfusion in the CO treated group (P = 0.040).

CONCLUSIONS

In this preclinical porcine model, CO application during EVLP resulted in better graft performance and outcomes after reperfusion.

Recent advances in carbon monoxide-releasing nanomaterials

As an endogenous signaling molecule, carbon monoxide (CO) has emerged as an increasingly promising option regarding as gas therapy due to its positive pharmacological effects in various diseases. Owing to the gaseous nature and potential toxicity, it is particularly important to modulate the CO release dosages and targeted locations to elucidate the biological mechanisms of CO and facilitate its clinical applications. Based on these, diverse CO-releasing molecules (CORMs) have been developed for controlled release of CO in biological systems. However, practical applications of these CORMs are limited by several disadvantages including low stability, poor solubility, weak releasing controllability, random diffusion, and potential toxicity. In light of rapid developments and diverse advantages of nanomedicine, abundant nanomaterials releasing CO in controlled ways have been developed for therapeutic purposes across various diseases. Due to their nanoscale sizes, diversified compositions and modified surfaces, vast CO-releasing nanomaterials (CORNMs) have been constructed and exhibited controlled CO release in specific locations under various stimuli with better pharmacokinetics and pharmacodynamics. In this review, we present the recent progress in CORNMs according to their compositions. Following a concise introduction to CO therapy, CORMs and CORNMs, the representative research progress of CORNMs constructed from organic nanostructures, hybrid nanomaterials, inorganic nanomaterials, and nanocomposites is elaborated. The basic properties of these CORNMs, such as active components, CO releasing mechanisms, detection methods, and therapeutic applications, are discussed in detail and listed in a table. Finally, we explore and discuss the prospects and challenges associated with utilizing nanomaterials for biological CO release.

Multiple Applications of a Novel Fluorescence Probe with Large Stokes Shift and Sensitivity for Rapid H2S Detection

Herein, a novel fluorescence probe Fla-DNP based on flavonol has been designed and synthesized for rapid, specific detection of H2S. With the addition of H2S, Fla-DNP triggered thiolysis and released Fla displaying the "turn-on" fluorescence response at 566 nm, which is consistent with the reaction site predicted by calculating Electrostatic potential and ADCH charges. As an easily available H2S probe, Fla-DNP has the advantages of high selectivity, anti-interference, low detection limit (0.834 μM), short response time (6 min), and large Stokes shift (124 nm). The sensing mechanism of H2S was determined by HRMS analysis and DFT calculation. Moreover, Fla-DNP processes a wide range of multiple applications, including the detection of H2S in environmental water samples with good recovery rates ranging from 89.6% to 102.0%, as well as tracking the production of H2S during food spoilage. Meanwhile, the probe exhibits superior biocompatibility and can not only be available used for H2S detection in living cells but be further designed as an H2S-activated CO photoreleaser, based on which it can be developed as a targeted anti-cancer drug.

Carbon Monoxide Poisoning: From Microbes to Therapeutics

Carbon monoxide (CO) poisoning leads to 50,000-100,000 emergency room visits and 1,500-2,000 deaths each year in the United States alone. Even with treatment, survivors often suffer from long-term cardiac and neurocognitive deficits, highlighting a clear unmet medical need for novel therapeutic strategies that reduce morbidity and mortality associated with CO poisoning. This review examines the prevalence and impact of CO poisoning and pathophysiology in humans and highlights recent advances in therapeutic strategies that accelerate CO clearance and mitigate toxicity. We focus on recent developments of high-affinity molecules that take advantage of the uniquely strong interaction between CO and heme to selectively bind and sequester CO in preclinical models. These scavengers, which employ heme-binding scaffolds ranging from organic small molecules to hemoproteins derived from humans and potentially even microorganisms, show promise as field-deployable antidotes that may rapidly accelerate CO clearance and improve outcomes for survivors of acute CO poisoning.

Multiconfigurational photodynamics simulations reveal the mechanism of photodecarbonylations of cyclopropenones in explicit aqueous environments

Gas-evolving photochemical reactions use light and mild conditions to access strained organic compounds irreversibly. Cyclopropenones are a class of light-responsive molecules used in bioorthogonal photoclick reactions; their excited-state decarbonylation reaction mechanisms are misunderstood due to their ultrafast (<100 femtosecond) lifetimes. We have combined multiconfigurational quantum mechanical (QM) calculations and non-adiabatic molecular dynamics (NAMD) simulations to uncover the excited-state mechanism of cyclopropenone and a photoprotected cyclooctyne-(COT)-precursor in gaseous and explicit aqueous environments. We explore the role of H-bonding with fully quantum mechanical explicitly solvated NAMD simulations for the decarbonylation reaction. The cyclopropenones pass through asynchronous conical intersections and have dynamically concerted photodecarbonylation mechanisms. The COT-precursor has a higher quantum yield of 55% than cyclopropenone (28%) because these trajectories prefer to break a σCC bond to avoid the strained trans-cyclooctene geometries. Our solvated simulations show an increased quantum yield (58%) for the systems studied here.

Carboxyhemoglobin (COHb): Unavoidable Bystander or Protective Player?

Carbon monoxide (CO) is a cytoprotective endogenous gas that is ubiquitously produced by the stress response enzyme heme-oxygenase. Being a gas, CO rapidly diffuses through tissues and binds to hemoglobin (Hb) increasing carboxyhemoglobin (COHb) levels. COHb can be formed in erythrocytes or in plasma from cell-free Hb. Herein, it is discussed as to whether endogenous COHb is an innocuous and inevitable metabolic waste product or not, and it is hypothesized that COHb has a biological role. In the present review, literature data are presented to support this hypothesis based on two main premises: (i) there is no direct correlation between COHb levels and CO toxicity, and (ii) COHb seems to have a direct cytoprotective and antioxidant role in erythrocytes and in hemorrhagic models in vivo. Moreover, CO is also an antioxidant by generating COHb, which protects against the pro-oxidant damaging effects of cell-free Hb. Up to now, COHb has been considered as a sink for both exogenous and endogenous CO generated during CO intoxication or heme metabolism, respectively. Hallmarking COHb as an important molecule with a biological (and eventually beneficial) role is a turning point in CO biology research, namely in CO intoxication and CO cytoprotection.

Cross-Regulation of the Cellular Redox System, Oxygen, and Sphingolipid Signalling

Redox-active mediators are now appreciated as powerful molecules to regulate cellular dynamics such as viability, proliferation, migration, cell contraction, and relaxation, as well as gene expression under physiological and pathophysiological conditions. These molecules include the various reactive oxygen species (ROS), and the gasotransmitters nitric oxide (NO∙), carbon monoxide (CO), and hydrogen sulfide (H2S). For each of these molecules, direct targets have been identified which transmit the signal from the cellular redox state to a cellular response. Besides these redox mediators, various sphingolipid species have turned out as highly bioactive with strong signalling potential. Recent data suggest that there is a cross-regulation existing between the redox mediators and sphingolipid molecules that have a fundamental impact on a cell’s fate and organ function. This review will summarize the effects of the different redox-active mediators on sphingolipid signalling and metabolism, and the impact of this cross-talk on pathophysiological processes. The relevance of therapeutic approaches will be highlighted.

Metal-Organic Frameworks as Intelligent Drug Nanocarriers for Cancer Therapy

Metal-organic frameworks (MOFs) are crystalline porous materials with periodic network structures formed by self-assembly of metal ions and organic ligands. Attributed to their tunable composition and pore size, ultrahigh surface area (1000-7000 m²/g) and pore volume (1.04-4.40 cm³/g), easy surface modification, appropriate physiological stability, etc., MOFs have been widely used in biomedical applications in the last two decades, especially for the delivery of bioactive agents. In the initial stage, MOFs were widely used to load small molecule drugs with ultra-high doses. Whereafter, more recent work has focused on the load of biomacromolecules, such as nucleic acids and proteins. Over the past years, we have devoted extensive effort to investigate the function of MOF materials for bioactive agent delivery. MOFs can be used not only as an intelligent nanocarrier to deliver or protect bioactive agents but also as an activator for their release or activation in response to the different microenvironments. Altogether, this review details the current progress of MOF materials for bioactive agent delivery and looks into their future development.

Role and Posttranslational Regulation of Cx46 Hemichannels and Gap Junction Channels in the Eye Lens

Connexins are a family of proteins that can form two distinct types of channels: hemichannels and gap junction channels. Hemichannels are composed of six connexin subunits and when open allow for exchanges between the cytoplasm and the extracellular milieu. Gap junction channels are formed by head-to-head docking of two hemichannels in series, each one from one of two adjacent cells. These channels allow for exchanges between the cytoplasms of contacting cells. The lens is a transparent structure located in the eye that focuses light on the retina. The transparency of the lens depends on its lack of blood irrigation and the absence of organelles in its cells. To survive such complex metabolic scenario, lens cells express Cx43, Cx46 and Cx50, three connexins isoforms that form hemichannels and gap junction channels that allow for metabolic cooperation between lens cells. This review focuses on the roles of Cx46 hemichannels and gap junction channels in the lens under physiological conditions and in the formation of cataracts, with emphasis on the modulation by posttranslational modifications.

Azaadamantanes, a New Promising Scaffold for Medical Chemistry

Azaadamantanes are nitrogen-containing analogs of adamantane, which contain one or more nitrogen atoms instead of carbon atoms. This substitution leads to several specific chemical and physical properties. The azaadamantane derivatives have less lipophilicity compared to their adamantane analogs, which affects both their interaction with biological targets and bioavailability. The significant increase in the number of publications during the last decade (2009-2020) concerning the study of reactivity and biological activity of azaadamantanes and their derivatives indicates a great theoretical and practical interest in these compounds. Compounds with pronounced biological activity have been already discovered among azaadamantane derivatives. The review is devoted to the biological activity of azaadamantanes and their derivatives. It presents the main methods for the synthesis of di- and triazaadamantanes and summarizes the accumulated data on studying the biological activity of these compounds. The prospects for the use of azaadamantanes in medical chemistry and pharmacology are discussed.

Endogenous Hemoprotein-Dependent Signaling Pathways of Nitric Oxide and Nitrite

Interdisciplinary research at the interface of chemistry, physiology, and biomedicine have uncovered pivotal roles of nitric oxide (NO) as a signaling molecule that regulates vascular tone, platelet aggregation, and other pathways relevant to human health and disease. Heme is central to physiological NO signaling, serving as the active site for canonical NO biosynthesis in nitric oxide synthase (NOS) enzymes and as the highly selective NO binding site in the soluble guanylyl cyclase receptor. Outside of the primary NOS-dependent biosynthetic pathway, other hemoproteins, including hemoglobin and myoglobin, generate NO via the reduction of nitrite. This auxiliary hemoprotein reaction unlocks a "second axis" of NO signaling in which nitrite serves as a stable NO reservoir. In this Forum Article, we highlight these NO-dependent physiological pathways and examine complex chemical and biochemical reactions that govern NO and nitrite signaling in vivo. We focus on hemoprotein-dependent reaction pathways that generate and consume NO in the presence of nitrite and consider intermediate nitrogen oxides, including NO2, N2O3, and S-nitrosothiols, that may facilitate nitrite-based signaling in blood vessels and tissues. We also discuss emergent therapeutic strategies that leverage our understanding of these key reaction pathways to target NO signaling and treat a wide range of diseases.

Amperometric Sensing of Carbon Monoxide: Improved Sensitivity and Selectivity via Nanostructure-Controlled Electrodeposition of Gold

A series of gold (Au) nanostructures, having different morphologies, were fabricated for amperometric selective detection of carbon monoxide (CO), a biologically important signaling molecule. Au layers were electrodeposited from a precursor solution of 7 mM HAuCl4 with a constant deposition charge (0.04 C) at various deposition potentials. The obtained Au nanostructures became rougher and spikier as the deposition potential lowered from 0.45 V to 0.05 V (vs. Ag/AgCl). As prepared Au layers showed different hydrophobicity: The sharper morphology, the greater hydrophobicity. The Au deposit formed at 0.05 V had the sharpest shape and the greatest surface hydrophobicity. The sensitivity of an Au deposit for amperometric CO sensing was enhanced as the Au surface exhibits higher hydrophobicity. In fact, CO selectivity over common electroactive biological interferents (L-ascorbic acid, 4-acetamidophenol, 4-aminobutyric acid and nitrite) was improved eminently once the Au deposit became more hydrophobic. The most hydrophobic Au was also confirmed to sense CO exclusively without responding to nitric oxide, another similar gas signaling molecule, in contrast to a hydrophobic platinum (Pt) counterpart. This study presents a feasible strategy to enhance the sensitivity and selectivity for amperometric CO sensing via the fine control of Au electrode nanostructures.

The potentials of carbon monoxide-releasing molecules in cancer treatment: An outlook from ROS biology and medicine

Carbon monoxide (CO) is now well recognized a pivotal endogenous signaling molecule in mammalian lives. The proof-of-concept employing chemical carriers of exogenous CO as prodrugs for CO release, also known as CO-releasing molecules (CO-RMs), has been appreciated. The major advantage of CO-RMs is that they are able to deliver CO to the target sites in a controlled manner. There is an increasing body of experimental studies suggesting the therapeutic potentials of CO and CO-RMs in different cancer models. This review firstly presents a short but crucial view concerning the characteristics of CO and CO-RMs. Then, the anticancer activities of CO-RMs that target many cancer hallmarks, mainly proliferation, apoptosis, angiogenesis, and invasion and metastasis, are discussed. However, their anticancer activities are varying and cell-type specific. The aerobic metabolism of molecular oxygen inevitably generates various oxygen-containing reactive metabolites termed reactive oxygen species (ROS) which play important roles in both physiology and pathophysiology. Although ROS act as a double-edged sword in cancer, both sides of which may potentially have been exploited for therapeutic benefits. The main focus of the present review is thus to identify the possible signaling network by which CO-RMs can exert their anticancer actions, where ROS play the central role. Another important issue concerning the potential effect of CO-RMs on the aerobic glycolysis (the Warburg effect) which is a feature of cancer metabolic reprogramming is given before the conclusion with future prospects on the challenges of developing CO-RMs into clinically pharmaceutical candidates in cancer therapy.

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CO-RMs as pro-drugs for controlled CO delivery are potentially beneficial in cancer treatment.

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Anticancer activities of CO-RMs are varying and cell-type specific.

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Anti-proliferative, pro-apoptotic, and anti-angiogenic effects are major niches.

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ROS may play a central role in the molecular pathways underlying anticancer activities of CO-RMs.

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CO-RMs can act against Warburg effect, a feature of cancer metabolic reprogramming.

'Carbon-Monoxide-Releasing Molecule-2 (CORM-2)' Is a Misnomer: Ruthenium Toxicity, Not CO Release, Accounts for Its Antimicrobial Effects

Carbon monoxide (CO)-releasing molecules (CORMs) are used to deliver CO, a biological ‘gasotransmitter’, in biological chemistry and biomedicine. CORMs kill bacteria in culture and in animal models, but are reportedly benign towards mammalian cells. CORM-2 (tricarbonyldichlororuthenium(II) dimer, Ru₂Cl₄(CO)₆), the first widely used and commercially available CORM, displays numerous pharmacological, biochemical and microbiological activities, generally attributed to CO release. Here, we investigate the basis of its potent antibacterial activity against Escherichia coli and demonstrate, using three globin CO sensors, that CORM-2 releases negligible CO (<0.1 mol CO per mol CORM-2). A strong negative correlation between viability and cellular ruthenium accumulation implies that ruthenium toxicity underlies biocidal activity. Exogenous amino acids and thiols (especially cysteine, glutathione and N-acetyl cysteine) protected bacteria against inhibition of growth by CORM-2. Bacteria treated with 30 μM CORM-2, with added cysteine and histidine, exhibited no significant loss of viability, but were killed in the absence of these amino acids. Their prevention of toxicity correlates with their CORM-2-binding affinities (Cys, K_d 3 μM; His, K_d 130 μM) as determined by ¹H-NMR. Glutathione is proposed to be an important intracellular target of CORM-2, with CORM-2 having a much higher affinity for reduced glutathione (GSH) than oxidised glutathione (GSSG) (GSH, K_d 2 μM; GSSG, K_d 25,000 μM). The toxicity of low, but potent, levels (15 μM) of CORM-2 was accompanied by cell lysis, as judged by the release of cytoplasmic ATP pools. The biological effects of CORM-2 and related CORMs, and the design of biological experiments, must be re-examined in the light of these data.

Carbon Monoxide and Nitric Oxide as Examples of the Youngest Class of Transmitters

The year 2021 is the 100th anniversary of the confirmation of the neurotransmission phenomenon by Otto Loewi. Over the course of the hundred years, about 100 neurotransmitters belonging to many chemical groups have been discovered. In order to celebrate the 100th anniversary of the confirmation of neurotransmitters, we present an overview of the first two endogenous gaseous transmitters i.e., nitric oxide, and carbon monoxide, which are often termed as gasotransmitters.

Cardiac function dependence on carbon monoxide

Nitric oxide, studied to evaluate its role in cardiovascular physiology, has cardioprotective and therapeutic effects in cellular signaling, mitochondrial function, and in regulating inflammatory processes. Heme oxygenase (major role in catabolism of heme into biliverdin, carbon monoxide (CO), and iron) has similar effects as well. CO has been suggested as the molecule that is responsible for many of the above mentioned cytoprotective and therapeutic pathways as CO is a signaling molecule in the control of physiological functions. This is counterintuitive as toxic effects are related to its binding to hemoglobin. However, CO is normally produced in the body. Experimental evidence indicates that this toxic gas, CO, exerts cytoprotective properties related to cellular stress including the heart and is being assessed for its cytoprotective and cytotherapeutic properties. While survival of adult cardiomyocytes depends on oxidative phosphorylation (survival and resulting cardiac function is impaired by mitochondrial damage), mitochondrial biogenesis is modified by the heme oxygenase-1/CO system and can result in promotion of mitochondrial biogenesis by associating mitochondrial redox status to the redox-active transcription factors. It has been suggested that the heme oxygenase-1/CO system is important in differentiation of embryonic stem cells and maturation of cardiomyocytes which is thought to mitigate progression of degenerative cardiovascular diseases. Effects on other cardiac cells are being studied. Acute exposure to air pollution (and, therefore, CO) is associated with cardiovascular mortality, myocardial infarction, and heart failure, but changes in the endogenous heme oxygenase-1 system (and, thereby, CO) positively affect cardiovascular health. We will review the effect of CO on heart health and function in this article.

Ischemia-Reperfusion Injury in Lung Transplantation

Lung transplantation has been established worldwide as the last treatment for end-stage respiratory failure. However, ischemia–reperfusion injury (IRI) inevitably occurs after lung transplantation. The most severe form of IRI leads to primary graft failure, which is an important cause of morbidity and mortality after lung transplantation. IRI may also induce rejection, which is the main cause of mortality in recipients. Despite advances in donor management and graft preservation, most donor grafts are still unsuitable for transplantation. Although the pulmonary endothelium is the primary target site of IRI, the pathophysiology of lung IRI remains incompletely understood. It is essential to understand the mechanism of pulmonary IRI to improve the outcomes of lung transplantation. Therefore, we reviewed the state-of-the-art in the management of pulmonary IRI after lung transplantation. Recently, the ex vivo lung perfusion (EVLP) system has been clinically introduced worldwide. Various promising therapeutic strategies for the protection of the endothelium against IRI, including EVLP, inhalation therapy with therapeutic gases and substances, fibrinolytic treatment, and mesenchymal stromal cell therapy, are awaiting clinical application. We herein review the latest advances in the field of pulmonary IRI in lung transplantation.

Metal-organic frameworks for therapeutic gas delivery

Nitric oxide (NO), carbon monoxide (CO), and hydrogen sulfide (H₂S) are gaseous signaling molecules (gasotransmitters) that regulate both physiological and pathological processes and offer therapeutic potential for the treatment of many diseases, such as cancer, cardiovascular disease, renal disease, bacterial and viral infections. However, the inherent labile nature of therapeutic gases results in difficulties in direct gases administration and their controlled delivery at clinically relevant ranges. Metal-organic frameworks (MOFs) with highly porous, stable, and easy-to-tailor properties have shown promising therapeutic gas delivery potential. Herein, we highlight the recent advances of MOF-based platforms for therapeutic gas delivery, either by endogenous (i.e., direct transfer of gases to targets) or exogenous (i.e., stimulating triggered release of gases) means. Reports that involve in vitro and/or in vivo studies are highlighted due to their high potential for clinical translation. Current challenges for clinical requirements and possible future innovative designs to meet variable healthcare needs are discussed.

CORM-2-entrapped ultradeformable liposomes ameliorate acute skin inflammation in an ear edema model via effective CO delivery

The short release half-life of carbon monoxide (CO) is a major obstacle to the effective therapeutic use of carbon monoxide-releasing molecule-2 (CORM-2). The potential of CORM-2-entrapped ultradeformable liposomes (CORM-2-UDLs) to enhance the release half-life of CO and alleviate skin inflammation was investigated in the present study. CORM-2-UDLs were prepared by using soy phosphatidylcholine to form lipid bilayers and Tween 80 as an edge activator. The deformability of CORM-2-UDLs was measured and compared with that of conventional liposomes by passing formulations through a filter device at a constant pressure. The release profile of CO from CORM-2-UDLs was evaluated by myoglobin assay. In vitro and in vivo anti-inflammatory effects of CORM-2-UDLs were assessed in lipopolysaccharide-stimulated macrophages and TPA-induced ear edema model, respectively. The deformability of the optimized CORM-2-UDLs was 2.3 times higher than conventional liposomes. CORM-2-UDLs significantly prolonged the release half-life of CO from 30 s in a CORM-2 solution to 21.6 min. CORM-2-UDLs demonstrated in vitro anti-inflammatory activity by decreasing nitrite production and pro-inflammatory cytokine levels. Furthermore, CORM-2-UDLs successfully ameliorated skin inflammation by reducing ear edema, pathological scores, neutrophil accumulation, and inflammatory cytokines expression. The results demonstrate that CORM-2-UDLs could be used as promising therapeutics against acute skin inflammation.

Carbon monoxide-releasing molecule-3: Amelioration of renal ischemia reperfusion injury in a rat model

Purpose

Despite the role of carbon monoxide in ameliorating ischemia-reperfusion injury (IRI), its use in the clinical setting is restricted owing to its toxicity. Herein, we investigated the in vivo effects of carbon monoxide–releasing molecule-3 (CORM-3) on IRI.

Materials and Methods

Fifteen rats were equally and randomly divided into three groups: sham (right nephrectomy), control (right nephrectomy and left renal ischemia), and CORM-3 (right nephrectomy and CORM-3 injection before left renal ischemia). Kidney tissues and blood samples collected from sacrificed rats were evaluated to determine the renoprotective effect and mechanism of CORM-3.

Results

Concentrations of serum creatinine and kidney injury molecule-1 in the CORM-3 group were significantly lower than in the control group after 75 minutes of IRI (1.2 vs. 2.4 mg/dL, p=0.01, and 292 vs. 550 pg/mL, p<0.001, respectively). Furthermore, the CORM-3 group exhibited a higher portion of normal tubules and glomeruli. TUNEL staining revealed fewer apoptotic renal tubular cells in the CORM-3 group than in the control group. The expression of 960 genes in the CORM-3 group was also altered. Pretreatment with CORM-3 before renal IRI produced a significant renoprotective effect. Fifteen of the altered genes were found to be involved in the peroxisome proliferator-activated receptors signaling pathway, and the difference in the expression of these genes between the CORM-3 and control groups was statistically significant (p<0.001).

Conclusions

CORM-3 ameliorates IRI by decreasing apoptosis and may be a novel strategy for protection against renal warm IRI.

Response of the cerebral vasculature to systemic carbon monoxide administration-Regional differences and sexual dimorphism

Previous studies about the modulation of the vasculature by CO were performed exclusively in male or sexually immature animals. Understanding the sex differences regarding systemic drug processing and pharmacodynamics is an important feature for safety assessment of drug dosing and efficacy. In this work, we used CORM-A1 as source of CO to examine the effects of this gasotransmitter on brain perfusion and the sex-dependent differences. Dynamic contrast-enhanced imaging (DCE)-based analysis was used to characterize the properties of CO in the modulation of cerebral vasculature in vivo, in adult C57BL/6 healthy mice. Perfusion of the temporal muscle, maxillary vein and in hippocampus, cortex and striatum was analysed for 108 min following CORM-A1 administration of 3 or 5 mg/kg. Under control conditions, brain perfusion was lower in females when compared with males. Under CO treatment, females showed a surprisingly overall reduced perfusion compared with controls (F = 3.452, p = .0004), while no major alterations (or even the expected increase) were observed in males. Cortical structures were only modulated in females. A striking female-dominated vasoconstriction effect was observed in the hippocampus and striatum following administration of CO, in this mixed-sex cohort. As these two regions are implicated in episodic and procedural memory formation, CO may have a relevant impact in learning and memory.

Exogenous carbon monoxide suppresses LPS-Induced platelet SNAREs complex assembly and α-granule exocytosis via integrin αIIbβ3-Mediated PKCθ/Munc18a pathway

Activation of coagulation occurs in sepsis and contributes to the development of thrombosis. Platelet α-granule exocytosis plays an important role in septic coagulation abnormalities. The present study aimed to investigate the effects and the underlying mechanisms of exogenous carbon monoxide, carbon monoxide-releasing molecules II (CORM-2)-liberated CO, on suppressing platelet α-granule exocytosis in sepsis. It was shown that CORM-2 weakened α-granule membrane fusion with platelet plasma membrane and attenuated α-granule contents exocytosis in LPS-Induced platelet. Further studies revealed that CORM-2 suppressed the expression of integrin α_IIbβ₃ in platelets stimulated by LPS. This was accompanied by a decrease in production and phosphorylation of PKCθ and Munc18a, SNARE complex assembly and subsequently platelet α-granule exocytosis. Taken together, we suggested that the potential mechanism of suppressive effect of CORM-2 on LPS-induced platelet SNAREs complex assembly and α-Granule Exocytosis might involve integrin α_IIbβ₃-mediated PKCθ/Munc18a pathway activation.

Carbon Monoxide and Cyanide Poisoning in the Burned Pregnant Patient: An Indication for Hyperbaric Oxygen Therapy

Carbon monoxide (CO) is a small molecule poison released as a product of incomplete combustion. Carbon monoxide binds hemoglobin, reducing oxygen delivery. This effect is exacerbated in the burned pregnant patient by fetal hemoglobin that binds CO 2.5- to 3-fold stronger than maternal hemoglobin. With no signature clinical symptom, diagnosis depends on patient injury history, elevated carboxyhemoglobin levels, and alterations in mental status. The standard of care for treatment of CO intoxication is 100% normobaric oxygen, which decreases the half-life of CO in the bloodstream from 5 hours to 1 hour. Hyperbaric oxygen (HBO2) is a useful adjunct to rapidly reduce the half-life of CO to 20 minutes and the incidence of delayed neurologic sequelae. Because of the slow disassociation of CO from hemoglobin in the fetus, there is a far stronger indication for HBO2 in the burned pregnant patient than in other burn patient populations.Cyanide intoxication is often a comorbid disease with CO in inhalation injury from an enclosed fire, but may be the predominant toxin. It acts synergistically with CO to effectively lower the lethal doses of both cyanide and CO. Diagnosis is best made in the presence of high lactate levels, carboxyhemoglobin concentrations greater than 10%, injury history of smoke inhalation from an enclosed fire, and alterations in consciousness. While treatment with hydroxocobalamin is the standard of care and has the effect of reducing concomitant CO toxicity, data indicate cyanide may also be displaced by HBO2.Carbon monoxide and cyanide poisoning presents potential complications impacting care. This review addresses the mechanism of action, presentation, diagnosis, and treatment of CO and cyanide poisonings in the burned pregnant patient and the use of HBO2 therapy.

Impact of Pharmacological Inhibition of Hydrogen Sulphide Production in the SOD1G93A-ALS Mouse Model

A number of factors can trigger amyotrophic lateral sclerosis (ALS), although its precise pathogenesis is still uncertain. In a previous study done by us, poisonous liquoral levels of hydrogen sulphide (H₂S) in sporadic ALS patients were reported. In the same study very high concentrations of H₂S in the cerebral tissues of the familial ALS (fALS) model of the SOD1G93A mouse, were measured. The objective of this study was to test whether decreasing the levels of H₂S in the fALS mouse could be beneficial. Amino-oxyacetic acid (AOA)—a systemic dual inhibitor of cystathionine-β-synthase and cystathionine-γ lyase (two key enzymes in the production of H₂S)—was administered to fALS mice. AOA treatment decreased the content of H₂S in the cerebral tissues, and the lifespan of female mice increased by approximately ten days, while disease progression in male mice was not affected. The histological evaluation of the spinal cord of the females revealed a significant increase in GFAP positivity and a significant decrease in IBA1 positivity. In conclusion, the results of the study indicate that, in the animal model, the inhibition of H₂S production is more effective in females. The findings reinforce the need to adequately consider sex as a relevant factor in ALS.

Different effects of partial pressure in a high-pressure gaseous mixture of carbon monoxide and oxygen for rat heart preservation

We maintained the function of an extracted rat heart after 24–48 h preservation in a high-pressure gaseous mixture of carbon monoxide (CO) and oxygen (O₂). Here, we assessed the effects of different partial pressures of hyperbaric CO and O₂ for 24–48 h at 4 °C on rat heart preservation and compared conditions including immersion in University of Wisconsin solution. Preserved hearts were transplanted into recipient rats via heterotopic cervical heart transplantation for in vivo evaluation and perfused using the Langendorff system for ex vivo evaluation. The survival rate of transplanted hearts was 100% at postoperative day 7 in the CO + O₂ (PCO:PO₂ = 1.5:2.0 atm) group but only 33% in the CO + O₂ (PCO:PO₂ = 2.0:1.5 atm) group. Langendorff system and histopathological analysis revealed that the left ventricular pressure of preserved hearts in the CO + O₂ (PCO:PO₂ = 1.5:2.0 atm) group was better than the CO + O₂ (PCO:PO₂ = 2.0:1.5 atm). We demonstrate that exposure of rat hearts to hyperbaric CO and O₂ is superior to the immersion method and that partial pressure of hyperbaric CO and O₂ is crucial to preservation.

Protective effects of carbon monoxide releasing molecule‑2 on pancreatic function in septic mice

The present study aimed to investigate the effect of carbon monoxide (CO)‑releasing molecule‑2 (CORM‑2) on pancreatic function in sepsis‑model mice. To perform the present investigation, mice were rendered septic by cecal ligation and puncture (CLP). Then, mice were either treated with or without CORM‑2 (8 mg/kg, intravenous) for different durations (6, 12 and 24 h) immediately following CLP. The levels of serum amylase and lipase, tumor necrosis factor α, interleukin‑1β and interleukin‑6 in addition to myeloperoxidase (MPO) activity in pancreatic tissues were determined at 6, 12 and 24 h post‑CLP. Histological scores and the expression of intercellular adhesion molecule 1 (ICAM‑1), vascular cell adhesion molecule 1 (VCAM‑1), nuclear factor‑κB (NF‑κB) and phosphorylated inhibitor of κB (p‑IκB‑α) in the pancreas were also evaluated at 24 h post‑CLP. The results of the present study revealed that compared with CLP‑alone group, CORM‑2 treatment significantly (P<0.05) reduced the levels of serum amylase, lipase and pro‑inflammatory cytokines. In parallel, the severity of pancreatic histology, MPO activity and the expression levels of ICAM‑1 and VCAM‑1 in the pancreas of CORM‑2 treated CLP mice were substantially decreased compared with the untreated group. Furthermore, CORM‑2 treatment inhibited the expression levels of NF‑κB and P‑IκB‑α in the pancreas of mice following CLP compared with the untreated group. CORM‑2‑liberated CO exerted protective effects on the pancreatic function of septic mice, and the beneficial effects may be due to the suppression of NF‑κB activation and subsequent regulation of NF‑κB‑dependent expression of cytokines.

Carbon monoxide (CO) and nitric dioxide (NO2) exposure during fetal life: impact on neonatal and placental weight, a prospective study

Objective: This prospective study aims to analyze how CO and NO₂ exposure during pregnancy affects birth and placental weight as well as umbilical arterial pH.Study design: The population in study includes 3614 women born in Italy, living in Lombardia Region, consecutively admitted to the Clinica Mangiagalli for an elective cesarean section from January 2004 to December 2006. Outdoor air quality data was provided by the Department of the Regional Environmental Protection Agency and obtained by a network of fixed monitoring stations distributed in eight geographical areas across the region.Results: A positive association was found between birth weight and the concentration of CO to whom women were exposed during the last 10 d of pregnancy (mean change g + 28, 95% CI +1 to +55, p .04). Conversely, placental weight was not influenced by exposure to CO while a statistically significant weight reduction was related to an increase in NO₂ exposure during the last trimester of pregnancy.Conclusion: Fetal weight was positively associated with an increased exposure to CO during the last 10 d of pregnancy. NO₂ exposure was associated to a placental weight reduction. These findings underline the existence of a complex biological role of such pollutants, especially of CO, in cell oxygenation at a placental level.

Neurointegrity and neurophysiology: astrocyte, glutamate, and carbon monoxide interactions

Astrocyte contributions to brain function and prevention of neuropathologies are as extensive as that of neurons. Astroglial regulation of glutamate, a primary neurotransmitter, is through uptake, release through vesicular and non-vesicular pathways, and catabolism to intermediates. Homeostasis by astrocytes is considered to be of primary importance in determining normal central nervous system health and central nervous system physiology - glutamate is central to dynamic physiologic changes and central nervous system stability. Gasotransmitters may affect diverse glutamate interactions positively or negatively. The effect of carbon monoxide, an intrinsic central nervous system gasotransmitter, in the complex astrocyte homeostasis of glutamate may offer insights to normal brain development, protection, and its use as a neuromodulator and neurotherapeutic. In this article, we will review the effects of carbon monoxide on astrocyte homeostasis of glutamate.

Do nitric oxide, carbon monoxide and hydrogen sulfide really qualify as 'gasotransmitters' in bacteria?

A gasotransmitter is defined as a small, generally reactive, gaseous molecule that, in solution, is generated endogenously in an organism and exerts important signalling roles. It is noteworthy that these molecules are also toxic and antimicrobial. We ask: is this definition of a gasotransmitter appropriate in the cases of nitric oxide, carbon monoxide and hydrogen sulfide (H₂S) in microbes? Recent advances show that, not only do bacteria synthesise each of these gases, but the molecules also have important signalling or messenger roles in addition to their toxic effects. However, strict application of the criteria proposed for a gasotransmitter leads us to conclude that the term ‘small molecule signalling agent’, as proposed by Fukuto and others, is preferable terminology.

Intermittent, low dose carbon monoxide exposure enhances survival and dopaminergic differentiation of human neural stem cells

Exploratory studies using human fetal tissue have suggested that intrastriatal transplantation of dopaminergic neurons may become a future treatment for patients with Parkinson's disease. However, the use of human fetal tissue is compromised by ethical, regulatory and practical concerns. Human stem cells constitute an alternative source of cells for transplantation in Parkinson's disease, but efficient protocols for controlled dopaminergic differentiation need to be developed. Short-term, low-level carbon monoxide (CO) exposure has been shown to affect signaling in several tissues, resulting in both protection and generation of reactive oxygen species. The present study investigated the effect of CO produced by a novel CO-releasing molecule on dopaminergic differentiation of human neural stem cells. Short-term exposure to 25 ppm CO at days 0 and 4 significantly increased the relative content of β-tubulin III-immunoreactive immature neurons and tyrosine hydroxylase expressing catecholaminergic neurons, as assessed 6 days after differentiation. Also the number of microtubule associated protein 2-positive mature neurons had increased significantly. Moreover, the content of apoptotic cells (Caspase3) was reduced, whereas the expression of a cell proliferation marker (Ki67) was left unchanged. Increased expression of hypoxia inducible factor-1α and production of reactive oxygen species (ROS) in cultures exposed to CO may suggest a mechanism involving mitochondrial alterations and generation of ROS. In conclusion, the present procedure using controlled, short-term CO exposure allows efficient dopaminergic differentiation of human neural stem cells at low cost and may as such be useful for derivation of cells for experimental studies and future development of donor cells for transplantation in Parkinson's disease.

Synthesis, functionalization, and applications of metal–organic frameworks in biomedicine

Metal–organic frameworks (MOFs), also known as coordination polymers, have attracted extensive research interest in the past few decades due to their unique physical structures and potentially vast applications.

Mesenchymal Stromal Cells Deficient in Autophagy Proteins Are Susceptible to Oxidative Injury and Mitochondrial Dysfunction

Oxidative stress resulting from inflammatory responses that occur during acute lung injury and sepsis can initiate changes in mitochondrial function. Autophagy regulates cellular processes in the setting of acute lung injury, sepsis, and oxidative stress by modulating the immune response and facilitating turnover of damaged cellular components. We have shown that mesenchymal stromal cells (MSCs) improve survival in murine models of sepsis by also regulating the immune response. However, the effect of autophagy on MSCs and MSC mitochondrial function during oxidative stress is unknown. This study investigated the effect of depletion of autophagic protein microtubule-associated protein 1 light chain 3B (LC3B) and beclin 1 (BECN1) on the response of MSCs to oxidative stress. MSCs were isolated from wild-type (WT) and LC3B^-/- or Becn1^+/- mice. MSCs from the LC3B^-/- and Becn1^+/- animals had increased susceptibility to oxidative stress-induced cell death as compared with WT MSCs. The MSCs depleted of autophagic proteins also had impaired mitochondrial function (decreased intracellular ATP, reduced mitochondrial membrane potential, and increased mitochondrial reactive oxygen species production) under oxidative stress as compared with WT MSCs. In WT MSCs, carbon monoxide (CO) preconditioning enhanced autophagy and mitophagy, and rescued the cells from oxidative stress-induced death. CO preconditioning was not able to rescue the decreased survival of MSCs from the LC3B^-/- and Becn1^+/- animals, further supporting the tenet that CO exerts its cytoprotective effects via the autophagy pathway.

Carbon Monoxide Improves Efficacy of Mesenchymal Stromal Cells During Sepsis by Production of Specialized Proresolving Lipid Mediators

Supplemental Digital Content is available in the text.

Objectives:

Mesenchymal stromal cells are being investigated as a cell-based therapy for a number of disease processes, with promising results in animal models of systemic inflammation and sepsis. Studies are ongoing to determine ways to further improve the therapeutic potential of mesenchymal stromal cells. A gas molecule that improves outcome in experimental sepsis is carbon monoxide. We hypothesized that preconditioning of mesenchymal stromal cells with carbon monoxide ex vivo would promote further therapeutic benefit when cells are administered in vivo after the onset of polymicrobial sepsis in mice.

Design:

Animal study and primary cell culture.

Setting:

Laboratory investigation.

Subjects:

BALB/c mice.

Interventions:

Polymicrobial sepsis was induced by cecal ligation and puncture. Mesenchymal stromal cells, mesenchymal stromal cells-conditioned with carbon monoxide, fibroblasts, or fibroblasts-conditioned with carbon monoxide were delivered by tail vein injections to septic mice. The mice were assessed for survival, bacterial clearance, and the inflammatory response during sepsis in each of the groups. Mesenchymal stromal cells were also assessed for their ability to promote bacterial phagocytosis by neutrophils, the production of specialized proresolving lipid mediators, and their importance for mesenchymal stromal cells function using gene silencing.

Measurements and Main Results:

Ex vivo preconditioning with carbon monoxide allowed mesenchymal stromal cells to be administered later after the onset of sepsis (6 hr), and yet maintain their therapeutic effect with increased survival. Carbon monoxide preconditioned mesenchymal stromal cells were also able to alleviate organ injury, improve bacterial clearance, and promote the resolution of inflammation. Mesenchymal stromal cells exposed to carbon monoxide, with docosahexaenoic acid substrate, produced specialized proresolving lipid mediators, particularly D-series resolvins, which promoted survival. Silencing of lipoxygenase pathways (5-lipoxygenase and 12/15-lipoxygenase), which are important enzymes for specialized proresolving lipid mediator biosynthesis, resulted in a loss of therapeutic benefit bestowed on mesenchymal stromal cells by carbon monoxide.

Conclusions:

Taken together, these data suggest that production of specialized proresolving lipid mediators contribute to improved mesenchymal stromal cell efficacy when exposed to carbon monoxide, resulting in an improved therapeutic response during sepsis.

The relationship between ambient carbon monoxide and heart rate variability-a systematic world review-2015

The objective of this report is to systematically review the literature pertaining to the evidence of the relationship between environmental carbon monoxide (CO) and heart rate variability (HRV). For this purpose, reports published in English scientific journals were critically reviewed by the authors employing PRISMA guidelines. Fifteen studies performed in China, Finland, Israel, Mexico, Taiwan, and the USA were identified as eligible to be included in the review. Out of these, 10 studies found a significant relationship between CO and HRV. However, while a proportion of these studies found an increase in parasympathetic tone, other studies found an increase in sympathetic tone. Methodological differences across these studies, including population understudy, sample size, measurement techniques, and accounting for intervening variables do not pave the way for a consensual conclusion. In conclusion, the lack of consistent results on the relationship between CO and HRV as reflected by the present review calls for more research employing appropriate indoor and outdoor ecological designs that account for possible interaction effects and individual differences. Involvement of olfactory receptors is suggested as a possible underlying mechanism for both short response latencies as well as for the diversity between individuals and samples investigated.

Fluorescent Probe Based on Azobenzene-Cyclopalladium for the Selective Imaging of Endogenous Carbon Monoxide under Hypoxia Conditions

Carbon monoxide (CO), a crucial gas message molecule, plays an important role in the regulation of physiological and pathological process. Hypoxia-induced CO is involved in modulating various cellular activities, including signal transduction, proliferation, and apoptosis. However, tracking CO fluctuation in the hypoxic cells is still a challenge due to lack of straightforward, visualized, and noninvasive tools. In this work, based on metal palladium-catalyzed reaction, we present the rational design, synthesis, and biological utility of an azobenzene-cyclopalladium-based fluorescent probe, ACP-2, for CO monitoring. ACP-2 exhibits capacity of detecting CO in aqueous buffer solution and live cells with high sensitivity and specificity. Utilizing ACP-2, we displayed a direct and visual evidence of endogenous CO up-regulation in live cells induced by hypoxia. Moreover, CO up-regulation during oxygen-glucose deprivation/reperfusion (OGD/R) was also imaged and certified by ACP-2.

Light-triggered CO delivery by a water-soluble and biocompatible manganese photoCORM

The discovery of salutary effects of low doses of carbon monoxide (CO) has spurred interest in designing exogenous molecules that can deliver CO to biological targets under controlled conditions. Herein we report a water-soluble photosensitive manganese carbonyl complex [MnBr(CO)3(pyTAm)] (2) (pyTAm = 2-(pyridyl)imino-triazaadamantane) that can be triggered to release CO upon exposure to visible light. Inclusion of a triazaadamantyl pharmacophore into the coligand of 2 improves its stability and solubility in water. Change in the coligand from 2-(pyridyl)imino-triazaadamantane to 2-(pyridyl)iminoadamantane (pyAm) or 2-(quinonyl)imino-triazaadamantane (qyTAm) dramatically alters these desired properties of the photoCORM. In addition to structures and CO-releasing properties of the three analogous complexes 1-3 from these three α-diimine ligands, theoretical calculations have been performed to determine the origin of Mn-CO bond labilization upon illumination. Rapid delivery of CO to myoglobin under physiological conditions attests the potential of 2 as a biocompatible photoCORM.

The emerging role of gasotransmitters in the pathogenesis of tuberculosis

Mycobacterium tuberculosis (Mtb) is a facultative intracellular pathogen and the second largest contributor to global mortality caused by an infectious agent after HIV. In infected host cells, Mtb is faced with a harsh intracellular environment including hypoxia and the release of nitric oxide (NO) and carbon monoxide (CO) by immune cells. Hypoxia, NO and CO induce a state of in vitro dormancy where Mtb senses these gases via the DosS and DosT heme sensor kinase proteins, which in turn induce a set of ∼47 genes, known as the Mtb Dos dormancy regulon. On the contrary, both iNOS and HO-1, which produce NO and CO, respectively, have been shown to be important against mycobacterial disease progression. In this review, we discuss the impact of O2, NO and CO on Mtb physiology and in host responses to Mtb infection as well as the potential role of another major endogenous gas, hydrogen sulfide (H2S), in Mtb pathogenesis.

Bactericidal Effect of a Photoresponsive Carbon Monoxide-Releasing Nonwoven against Staphylococcus aureus Biofilms

Staphylococcus aureus is a leading pathogen in skin and skin structure infections, including surgical and traumatic infections that are associated with biofilm formation. Because biofilm formation is accompanied by high phenotypic resistance of the embedded bacteria, they are almost impossible to eradicate by conventional antibiotics. Therefore, alternative therapeutic strategies are of high interest. We generated nanostructured hybrid nonwovens via the electrospinning of a photoresponsive carbon monoxide (CO)-releasing molecule [CORM-1, Mn2(CO)10] and the polymer polylactide. This nonwoven showed a CO-induced antimicrobial activity that was sufficient to reduce the biofilm-embedded bacteria by 70% after photostimulation at 405 nm. The released CO increased the concentration of reactive oxygen species (ROS) in the biofilms, suggesting that in addition to inhibiting the electron transport chain, ROS might play a role in the antimicrobial activity of CORMs on S. aureus The nonwoven showed increased cytotoxicity on eukaryotic cells after longer exposure, most probably due to the released lactic acid, that might be acceptable for local and short-time treatments. Therefore, CO-releasing nonwovens might be a promising local antimicrobial therapy against biofilm-associated skin wound infections.

The production of multi-transgenic pigs: update and perspectives for xenotransplantation

The domestic pig shares many genetic, anatomical and physiological similarities to humans and is thus considered to be a suitable organ donor for xenotransplantation. However, prior to clinical application of porcine xenografts, three major hurdles have to be overcome: (1) various immunological rejection responses, (2) physiological incompatibilities between the porcine organ and the human recipient and (3) the risk of transmitting zoonotic pathogens from pig to humans. With the introduction of genetically engineered pigs expressing high levels of human complement regulatory proteins or lacking expression of α-Gal epitopes, the HAR can be consistently overcome. However, none of the transgenic porcine organs available to date was fully protected against the binding of anti-non-Gal xenoreactive natural antibodies. The present view is that long-term survival of xenografts after transplantation into primates requires additional modifications of the porcine genome and a specifically tailored immunosuppression regimen compliant with current clinical standards. This requires the production and characterization of multi-transgenic pigs to control HAR, AVR and DXR. The recent emergence of new sophisticated molecular tools such as Zinc-Finger nucleases, Transcription-activator like endonucleases, and the CRISPR/Cas9 system has significantly increased efficiency and precision of the production of genetically modified pigs for xenotransplantation. Several candidate genes, incl. hTM, hHO-1, hA20, CTLA4Ig, have been explored in their ability to improve long-term survival of porcine xenografts after transplantation into non-human primates. This review provides an update on the current status in the production of multi-transgenic pigs for xenotransplantation which could bring porcine xenografts closer to clinical application.

Effects of carbon monoxide-releasing molecules on pulmonary vasoreactivity in isolated perfused lungs

In addition to its renowned poisonous effects, carbon monoxide (CO) is being recognized for its beneficial actions on inflammatory and vasoregulatory pathways, particularly when applied at low concentrations via CO-releasing molecules (CO-RMs). In the lung, CO gas and CO-RMs are suggested to decrease pulmonary vascular tone and hypoxic pulmonary vasoconstriction (HPV). However, the direct effect of CO-RMs on the pulmonary vasoreactivity in isolated lungs has not yet been investigated. We assessed the effect of CORM-2 and CORM-3 on the pulmonary vasculature during normoxia and acute hypoxia (1% oxygen for 10 min) in isolated ventilated and perfused mouse lungs. The effects were compared with those of inhaled CO gas (10%). The interaction of CORM-2 or CO with cytochrome P-450 (CYP) was measured simultaneously by tissue spectrophotometry. Inhaled CO decreased HPV and vasoconstriction induced by the thromboxane mimetic U-46619 but did not alter KCl-induced vasoconstriction. In contrast, concentrations of CORM-2 and CORM-3 used to elicit beneficial effects on the systemic circulation did not affect pulmonary vascular tone. High concentration of CO-RMs or long-term application induced a continuous increase in normoxic pressure. Inhaled CO showed spectral alterations correlating with the inhibition of CYP. In contrast, during application of CORM-2 spectrophotometric signs of interaction with CYP could not be detected. Application of CO-RMs in therapeutic doses in isolated lungs neither decreases pulmonary vascular tone and HPV nor does it induce spectral alterations that are characteristic of CO-inhibited CYP. High doses, however, may cause pulmonary vasoconstriction.

Carbon Monoxide-Releasing Molecule-2 Reduces Intestinal Epithelial Tight-Junction Damage and Mortality in Septic Rats

Objective

Damage to intestinal epithelial tight junctions plays an important role in sepsis. Recently we found that Carbon Monoxide-Releasing Molecule-2 (CORM-2) is able to protect LPS-induced intestinal epithelial tight junction damage and in this study we will investigate if CORM-2 could protect intestinal epithelial tight junctions in the rat cecal ligation and puncture (CLP) model.

Materials and Methods

The CLP model was generated using male Sprague-Dawley (SD) rats according to standard procedure and treated with CORM-2 or inactive CORM-2 (iCORM-2), 8 mg/kg, i.v. immediately after CLP induction and euthanized after 24h or 72h (for mortality rate only). Morphological changes were investigated using both transmission electron and confocal microscopy. The levels of important TJ proteins and phosphorylation of myosin light chain (MLC) were examined using Western blotting. Cytokines, IL-1β and TNF-α were measured using ELISA kits. The overall intestinal epithelial permeability was evaluated using FD-4 as a marker.

Results

CORM-2, but not iCORM-2, significantly reduced sepsis-induced damage of intestinal mucosa (including TJ disruption), TJ protein reduction (including zonula occludens-l (ZO-1), claudin-1 and occludin), MLC phosphorylation and proinflammatory cytokine release. The overall outcomes showed that CORM-2 suppressed sepsis-induced intestinal epithelial permeability changes and reduced mortality rate of those septic rats.

Conclusions

Our data strongly suggest that CORM-2 could be a potential therapeutic reagent for sepsis by suppressing inflammation, restoring intestinal epithelial barrier and reducing mortality.

Heat shock proteins and hormesis in the diagnosis and treatment of neurodegenerative diseases

Modulation of endogenous cellular defense mechanisms via the vitagene system represents an innovative approach to therapeutic intervention in diseases causing chronic tissue damage, such as in neurodegeneration. The possibility of high-throughoutput screening using proteomic techniques, particularly redox proteomics, provide more comprehensive overview of the interaction of proteins, as well as the interplay among processes involved in neuroprotection. Here by introducing the hormetic dose response concept, the mechanistic foundations and applications to the field of neuroprotection, we discuss the emerging role of heat shock protein as prominent member of vitagene network in neuroprotection and redox proteomics as a tool for investigating redox modulation of stress responsive vitagenes. Hormetic mechanisms are reviewed as possibility of targeted therapeutic manipulation in a cell-, tissue- and/or pathway-specific manner at appropriate points in the neurodegenerative disease process.