Rectal administration of carbon monoxide inhibits the development of intestinal inflammation and promotes intestinal wound healing via the activation of the Rho-kinase pathway in rats.

The inhalation of carbon monoxide (CO) gas and the administration of CO-releasing molecules were shown to inhibit the development of intestinal inflammation in a murine colitis model. However, it remains unclear whether CO promotes intestinal wound healing. Herein, we aimed to evaluate the therapeutic effects of the topical application of CO-saturated saline enemas on intestinal inflammation and elucidate the underlying mechanism. Acute colitis was induced with trinitrobenzene sulfonic acid (TNBS) in male Wistar rats. A CO-saturated solution was prepared via bubbling 50% CO gas into saline and was rectally administrated twice a day after colitis induction; rats were sacrificed 3 or 7 days after induction for the study of the acute or healing phases, respectively. The distal colon was isolated, and ulcerated lesions were measured. In vitro wound healing assays were also employed to determine the mechanism underlying rat intestinal epithelial cell restitution after CO treatment. CO solution rectal administration ameliorated acute TNBS-induced colonic ulceration and accelerated ulcer healing without elevating serum CO levels. The increase in thiobarbituric acid-reactive substances and myeloperoxidase activity after induction of acute TNBS colitis was also significantly inhibited after CO treatment. Moreover, the wound healing assays revealed that the CO-saturated medium enhanced rat intestinal epithelial cell migration via the activation of Rho-kinase. In addition, the activation of Rho-kinase in response to CO treatment was confirmed in the inflamed colonic tissue. Therefore, the rectal administration of a CO-saturated solution protects the intestinal mucosa from inflammation and accelerates colonic ulcer healing through enhanced epithelial cell restitution. CO may thus represent a novel therapeutic agent for the treatment of inflammatory bowel disease.

Carbon monoxide protects the kidney through the central circadian clock and CD39.

Ischemia reperfusion injury (IRI) is the predominant tissue insult associated with organ transplantation. Treatment with carbon monoxide (CO) modulates the innate immune response associated with IRI and accelerates tissue recovery. The mechanism has been primarily descriptive and ascribed to the ability of CO to influence inflammation, cell death, and repair. In a model of bilateral kidney IRI in mice, we elucidate an intricate relationship between CO and purinergic signaling involving increased CD39 ectonucleotidase expression, decreased expression of Adora1, with concomitant increased expression of Adora2a/2b. This response is linked to a >20-fold increase in expression of the circadian rhythm protein Period 2 (Per2) and a fivefold increase in serum erythropoietin (EPO), both of which contribute to abrogation of kidney IRI. CO is ineffective against IRI in Cd39-/- and Per2-/- mice or in the presence of a neutralizing antibody to EPO. Collectively, these data elucidate a cellular signaling mechanism whereby CO modulates purinergic responses and circadian rhythm to protect against injury. Moreover, these effects involve CD39- and adenosinergic-dependent stabilization of Per2. As CO also increases serum EPO levels in human volunteers, these findings continue to support therapeutic use of CO to treat IRI in association with organ transplantation, stroke, and myocardial infarction.

Carbon monoxide: An emerging therapy for acute kidney injury.

Treating acute kidney injury (AKI) represents an important unmet medical need both in terms of the seriousness of this medical problem and the number of patients. There is also a large untapped market opportunity in treating AKI. Over the years, there has been much effort in search of therapeutics with minimal success. However, over the same time period, new understanding of the underlying pathobiology and molecular mechanisms of kidney injury have undoubtedly helped the search for new therapeutics. Along this line, carbon monoxide (CO) has emerged as a promising therapeutic agent because of its demonstrated cytoprotective, and immunomodulatory effects. CO has also been shown to sensitize cancer, but not normal cells, to chemotherapy. This is particularly important in treating cisplatin-induced AKI, a common clinical problem that develops in patients receiving cisplatin therapies for a number of different solid organ malignancies. This review will examine and make the case that CO be developed into a therapeutic agent against AKI.

Carbon Monoxide Rescues the Developmental Lethality of Experimental Rat Models of Rhabdomyolysis-Induced Acute Kidney Injury.

Many victims, after being extricated from a collapsed building as the result of a disaster, suffer from disaster nephrology, a term that is referred to as the crush syndrome (CS). Recommended treatments, which include dialysis or the continuous administration of massive amounts of fluid are not usually easy in cases of such mass natural disasters. In the present study, we examined the therapeutic performance of a biomimetic carbon monoxide (CO) delivery system, CO-enriched red blood cells (CO-RBCs), on experimental animal models of an acute kidney injury (AKI) induced by traumatic and nontraumatic rhabdomyolysis, including CS and rhabdomyolysis with massive hemorrhage shock. A single CO-RBC treatment was found to effectively suppress the pathogenesis of AKI with the mortality in these model rats being improved. In addition, in further studies using glycerol-induced rhabdomyolysis model rats, the pathogenesis of which is similar to that for the CS, AKI and mortality were also reduced as the result of a CO-RBC treatment. Furthermore, CO-RBCs were found to have renoprotective effects via the suppression of subsequent heme protein-associated renal oxidative injury; the oxidation of myoglobin in the kidneys, the generation of reactive oxygen species by free heme produced from degraded-cytochrome P450 and hemoglobin-associated renal injury. Because CO-RBCs can be prepared and used at both hospitals and at a disaster site, these findings suggest that CO-RBCs have the potential for use as a novel cell therapy against both nontraumatic and traumatic rhabdomyolysis including CS-induced AKI. SIGNIFICANCE STATEMENT: After mass natural and man-made disasters, people who are trapped in collapsed buildings are in danger of acute kidney injury (AKI), including crush syndrome (CS)-related AKI. This paper reports that carbon monoxide-enriched red blood cells (CO-RBCs), which can be prepared at both hospitals and disaster sites, dramatically suppressed the pathogenesis of CS-related AKI, thus improving mortality via suppressing heme protein-associated renal injuries. CO-RBCs have the potential for serving as a practical therapeutic agent against disaster nephrology associated with the CS.

Intermittent low dose carbon monoxide inhalation does not influence glucose regulation in overweight adults: a randomized controlled crossover trial.

NEW FINDINGS: What is the central question of this study? Low dose carbon monoxide (CO) inhalation plays a role in regulating proteins involved in glucose metabolism; does low dose CO improve glucose and insulin responses to an oral glucose tolerance test in overweight adults? What is the main finding and its importance? Five days of intermittent CO inhalation does not alter the glucose or insulin responses to ingestion of a glucose bolus in overweight adults. Low dose CO is utilized in various physiological assessment procedures; these findings allow researchers and clinicians to utilize these procedures without concern of altering glucose metabolism. ABSTRACT: Low dose carbon monoxide (CO) inhalation upregulates several proteins important for glucose metabolism. Such changes could be clinically significant and may be relevant to those who use CO as a research tool. We hypothesized that low dose CO inhalation would improve glucose and insulin responses to an oral glucose bolus in overweight humans. Eleven young adults (5 men, 6 women; body mass index: 25-35 kg m-2 ) were included in this randomized, placebo-controlled, single-blinded crossover study. Following screening, participants completed two 7-day protocols with a 4-week washout. Twenty-four hours prior to and following five consecutive days of either once daily CO (men: 1.2 ml (kg body mass)-1 ; women: 1.0 ml (kg body mass)-1 ) or placebo (room air) inhalation, participants underwent oral glucose tolerance tests (OGTT). For key outcome variables, there were no significant main effects or interactions across condition or time point (mean ± SD), including fasting glucose (mg dl-1 : pre-placebo: 85.2 ± 10.1; post-placebo: 82.9 ± 10.6; pre-CO: 83.6 ± 7.7; post-CO: 84.0 ± 9.0), 2 h post glucose (mg dl-1 : pre-placebo: 100.9 ± 20.0; post-placebo: 98.7 ± 13.1; pre-CO: 94.2 ± 23.2; post-CO: 94.4 ± 14.9), or the Matsuda index (pre-placebo: 16.1 ± 11.5; post-placebo: 20.3 ± 24.7; pre-CO: 15.6 ± 15.3; post-CO: 17.5 ± 16.8). In conclusion, 5 days of low dose CO administration did not influence glucose and insulin responses to an OGTT in overweight adults. Low dose CO inhalation is utilized in a variety of physiological assessment procedures; these findings allow researchers to utilize these procedures without concern of altering glucose metabolism.

Systemic vasoprotection by inhaled carbon monoxide is mediated through prolonged alterations in monocyte/macrophage function.

Carbon monoxide (CO) is anti-inflammatory and protective in models of disease. Its actions in vitro are short-lived but are sustained in vivo. We hypothesize that systemic CO can mediate prolonged phenotype changes in vivo, with a focus on macrophages (Mφs). Mφs isolated from CO treated rats responded to lipopolysaccharide (LPS) with increased IL6, IL10 and iNOS expression but decreased TNF. Conditioned media (CM) collected from peritoneal Mφs isolated from CO treated rats stimulated endothelial cell (EC) proliferation versus CM from Mφs from air treated rats. This effect was mediated by Mφ released VEGF and HMGB1. Inhaled CO reduced LPS induced Mφ M1 inflammatory phenotype for up to 5 days. Mitochondrial oxygen consumption in LPS treated Mφs from CO treated mice was preserved compared to LPS treated Mφs from control mice. Finally, transient reduction of inflammatory cells at the time of inhaled CO treatment eliminated the vasoprotective effect of CO in a rodent carotid injury model. Thus, inhaled CO induces a prolonged mixed phenotype change in Mφs, and potentially other inflammatory cells, that contribute to vasoprotection. These findings demonstrate the ability of inhaled CO to modify Mφs in a sustained manner to mediate its therapeutic actions, supporting the translational potential of inhaled CO.

Breathing Micelles for Combinatorial Treatment of Rheumatoid Arthritis.

Breathing process involves inhalation and exhalation of different gases in animals. The gas exchange of the breathing process plays a critical role in maintaining the physiological functions of living organisms. Although artificial breathing materials exhibiting volume expansion and contraction upon alternate exposure to different gases have been well explored, those being able to realize the gas exchange remain elusive. Herein, we report breathing micelles (BM) capable of inhaling nitric oxide (NO) and exhaling carbon monoxide (CO), both of which are endogenous gaseous signaling molecules. We demonstrate that BM can simultaneously scavenge overproduced NO and attenuate proinflammatory cytokines in lipopolysaccharide (LPS)-challenged macrophage cells. In vivo studies revealed that BM outperformed conventional nonsteroidal anti-inflammatory drugs such as dexamethasone (Dexa) in treatment of rheumatoid arthritis (RA) in adjuvant-induced arthritis (AIA) rats, likely due to the combinatorial effect of NO depletion, CO-mediated deactivation of inducible NO synthase (iNOS) and activation of heme oxygenase-1 (HO-1). This work provides new insights into artificial BM for potential biomedical applications.

Extracorporeal resuscitation with carbon monoxide improves renal function by targeting inflammatory pathways in cardiac arrest in pigs.

Deleterious consequences like acute kidney injury frequently occur upon successful resuscitation from cardiac arrest. Extracorporeal life support is increasingly used to overcome high cardiac arrest mortality. Carbon monoxide (CO) is an endogenous gasotransmitter, capable of reducing renal injury. In our study, we hypothesized that addition of CO to extracorporeal resuscitation hampers severity of renal injury in a porcine model of cardiac arrest. Hypoxic cardiac arrest was induced in pigs. Animals were resuscitated using a conventional [cardiopulmonary resuscitation (CPR)], an extracorporeal (E-CPR), or a CO-assisted extracorporeal (CO-E-CPR) protocol. CO was applied using a membrane-controlled releasing system. Markers of renal injury were measured, and histopathological analyses were carried out. We investigated renal pathways involving inflammation as well as apoptotic cell death. No differences in serum neutrophil gelatinase-associated lipocalin (NGAL) were detected after CO treatment compared with Sham animals (Sham 71 ± 7 and CO-E-CPR 95 ± 6 ng/mL), while NGAL was increased in CPR and E-CPR groups (CPR 135 ± 11 and E-CPR 124 ± 5 ng/mL; P < 0.05). Evidence for histopathological damage was abrogated after CO application. CO increased renal heat shock protein 70 expression and reduced inducible cyclooxygenase 2 (CPR: 60 ± 8; E-CPR 56 ± 8; CO-E-CPR 31 ± 3 µg/mL; P < 0.05). Caspase 3 activity was decreased (CPR 1,469 ± 276; E-CPR 1,670 ± 225; CO-E-CPR 755 ± 83 pg/mL; P < 0.05). Furthermore, we found a reduction in renal inflammatory signaling upon CO treatment. Our data demonstrate improved renal function by extracorporeal CO treatment in a porcine model of cardiac arrest. CO reduced proinflammatory and proapoptotic signaling, characterizing beneficial aspects of a novel treatment option to overcome high mortality.

Emerging Delivery Strategies of Carbon Monoxide for Therapeutic Applications: from CO Gas to CO Releasing Nanomaterials.

Carbon monoxide (CO) therapy has emerged as a hot topic under exploration in the field of gas therapy as it shows the promise of treating various diseases. Due to the gaseous property and the high affinity for human hemoglobin, the main challenges of administrating medicinal CO are the lack of target selectivity as well as the toxic profile at relatively high concentrations. Although abundant CO releasing molecules (CORMs) with the capacity to deliver CO in biological systems have been developed, several disadvantages related to CORMs, including random diffusion, poor solubility, potential toxicity, and lack of on-demand CO release in deep tissue, still confine their practical use. Recently, the advent of versatile nanomedicine has provided a promising chance for improving the properties of naked CORMs and simultaneously realizing the therapeutic applications of CO. This review presents a brief summarization of the emerging delivery strategies of CO based on nanomaterials for therapeutic application. First, an introduction covering the therapeutic roles of CO and several frequently used CORMs is provided. Then, recent advancements in the synthesis and application of versatile CO releasing nanomaterials are elaborated. Finally, the current challenges and future directions of these important delivery strategies are proposed.

Inhaled carbon monoxide increases vasodilation in the microvascular circulation.

Preeclampsia (PE) is characterized by systemic maternal endothelial dysfunction. Changes in endothelial reactivity have been reported before the onset of clinical signs of PE, and continuing into the post-partum period. Women who smoke during pregnancy have a 33% reduced risk of developing PE. This reduced risk is hypothesized to be, in part, attributed to carbon monoxide (CO), a by-product of cigarette combustion and a known endogenous vasodilator. Determining the vascular effects of CO in healthy women, may inform how CO can improve endothelial function and have promise as a novel therapeutic for PE. As part of a pilot study to determine the vascular effects of CO, the aim of this study was to measure microvascular vasodilation following low-dose CO inhalation. Non-pregnant women inhaled ambient room air or 250 ppm CO for 24 min during microvascular assessment using laser speckle contrast imaging. Changes in vascular flux were measured in the forearm before, during, and following a three-minute arterial occlusion. CO inhalation increased end-tidal breath CO (EtCO) (9.1 ±â€¯1.9 vs. 1.8 ±â€¯0.7 ppm, p < 0.05) and increased microvascular vasodilation, measured as difference of maximum level/resting level ratio (mean difference 0.476, 95% confidence interval (CI) = 0.149-0.802 vs. 0.118, 95% CI = -0.425-0.662, p < 0.05). Women who inhaled CO had a longer time to half recovery of endothelial function following arterial occlusion, compared to controls (hazard ratio 0.29, 95% CI = 0.10-0.91, p = 0.033). Inhalation of CO moderately increased EtCO and resulted in an increased microvascular response, suggesting that CO may have potential as a therapeutic for PE.

Modification of the CO-rebreathing method to determine haemoglobin mass and blood volume in patients suffering from chronic mountain sickness.

NEW FINDINGS: What is the central question of this study? Is it necessary to modify the CO-rebreathing method to acquire reliable measurements of haemoglobin mass in patients with chronic mountain sickness? What is the main finding and its importance? The CO-rebreathing method must be modified because of the prolonged CO-mixing time in patients with chronic mountain sickness. After adaptation of the blood sampling method, reliable and valid results were attained. With this modification, it is possible to quantify the extent of polycythaemia and to distinguish between a haemoconcentration and an exclusive enhancement of erythrocyte volume. ABSTRACT: Patients suffering from chronic mountain sickness (CMS) exhibit extremely high haemoglobin concentrations. Their haemoglobin mass (Hbmass), however, has rarely been investigated. The CO-rebreathing protocol for Hbmass determination in those patients might need to be modified because of restricted peripheral perfusion. The aim of this study was to evaluate the CO uptake and carboxyhaemoglobin-mixing time in the blood of CMS patients and to adapt the CO-rebreathing method for this group. Twenty-five male CMS patients living at elevations between 3600 and 4100 m above sea level were compared with ethnically matched healthy control subjects from identical elevations (n = 11) and near sea level (n = 9) and with a Caucasian group from sea level (n = 6). CO rebreathing was performed for 2 min, and blood samples were taken for the subsequent 30 min. After the method was modified, its reliability was evaluated in test-retest experiments (n = 28), and validity was investigated by measuring the Hbmass before and after the phlebotomy of 500 ml (n = 4). CO uptake was not affected by CMS. The carboxyhaemoglobin mixing was completed after 8 min in the Caucasian group but after 14 min in the groups living at altitude. When blood was sampled 14-20 min after inhalation, the typical error of the method was 1.6% (confidence limits 1.2-2.5%). After phlebotomy, Hbmass decreased from 1779 ± 123 to 1650 ± 129 g, and no difference was found between the measured and calculated Hbmass (1666 ± 122 g). When the time of blood sampling was adapted to accommodate a prolonged carboxyhaemoglobin-mixing time, the CO-rebreathing method became a reliable and valid tool to determine Hbmass in CMS patients.

Programmed ROS/CO-releasing nanomedicine for synergetic chemodynamic-gas therapy of cancer.

BACKGROUND: To improve the outcome of cancer treatment, the combination of multiple therapy models has proved to be effective and promising. Gas therapy (GT) and chemodynamic therapy (CDT), mainly targeting the mitochondrion and nucleus, respectively, are two emerging strategy for anti-cancer. The development of novel nanomedicine for integrating these new therapy models is greatly significant and highly desired. METHODS: A new nanomedicine is programmed by successive encapsulation of MnO2 nanoparticles and iron carbonyl (FeCO) into mesoporous silica nanoparticle. By decoding the nanomedicine, acidity in the lysosome drives MnO2 to generate ROS, ·OH among which further triggers the decomposition of FeCO into CO, realizing the effective combination of chemodynamic therapy with gas therapy for the first time. RESULTS: Acidity in the TEM drives MnO2 to generate ROS, ∙OH among which further triggers the decomposition of FeCO into CO, realizing the effective combination of CDT and CDGT. The co-released ROS and CO do damage to DNA and mitochondria of various cancer cells, respectively. The mitochondrial damage can effectively cut off the ATP source required for DNA repair, causing a synergetic anti-cancer effect in vitro and in vivo. CONCLUSIONS: The combination of CDT and CDGT causing a synergetic anti-cancer effect in vitro and in vivo. The proposed therapy concept and nanomedicine designing strategy might open a new window for engineering high-performance anti-cancer nanomedicine.

Carbon Monoxide Attenuates Lipopolysaccharides (LPS)-Induced Acute Lung Injury in Neonatal Rats via Downregulation of Cx43 to Reduce Necroptosis.

BACKGROUND Acute lung injury (ALI) is one of major causes of death in newborns, making it urgent to improve therapy. Administration of low dose carbon monoxide (CO) plays a protective role in ALI but the mechanisms are not fully understood. This study was designed to test the therapeutic effect of monoxide-releasing molecule 3 (MORM3) in lipopolysaccharide (LPS) induced neonatal ALI and the possibly associated molecular mechanisms. MATERIAL AND METHODS For this study, 3- to 8-day old Newborn Sprague-Dawley rats were subjected to intraperitoneal injection of 3 mg/kg LPS to induce ALI. Then animals received intraperitoneal injection of carbon monoxide-releasing molecules 3 (CORM3) (8 mg/kg) or inactive CORM3 (iCORM3) for 7 consecutive days. Lung tissues were collected for histological examination and total cell counts and protein content in bronchoalveolar lavage fluid (BALF) were measured. Expression of Cx43 and necroptosis-related markers were detected by quantitative real-time polymerase chain reaction (qRT-PCR) and western blot. RESULTS LPS exposure induced significant lung injury indicated by histological damage, increased lung wet/dry weight ratio (W/D) and increased total cell counts and protein concentration in BALF. These changes were significantly ameliorated by administration of CORM3 but not iCORM3. LPS also increased necroptosis-related markers RIP1, RIP3, and MLKL and their elevation was blocked by CORM3. CORM3 administration ameliorated LPS induced elevation of Cx43 expression and adenoviral overexpression of Cx43 abolished lung protective effect of CORM3. CORM3 administration attenuated LPS induced activation of extracellular-signal-regulated kinase (ERK) and its protection against necroptosis was abolished by ERK inhibitor U0126. CONCLUSIONS CORM3 attenuates LPS-Induced ALI in neonatal rats and its lung protective effect might be through downregulation of Cx43 to attenuate ERK signaling and ameliorate necroptosis, suggesting CORM3 as a potential therapeutic drug for ALI in neonates.

User-oriented independent analysis of the toxic load model's ability to predict the effects of time-varying toxic inhalation exposures.

Toxic industrial chemicals and chemical warfare agents present an acute inhalation hazard to exposed populations. The hazardous materials consequence assessment modeling community requires toxicity models to estimate these hazards. One popular phenomenological toxicity model is the toxic load model. Although this model is only well-defined for constant-concentration exposures, several generalizations have been proposed for the case of time-varying exposures. None of them, however, were validated by experimental evidence at the time they were proposed. Accordingly, the Defense Threat Reduction Agency (DTRA) sponsored experiments to explore the effects of time-varying inhalation exposures of hydrogen cyanide (HCN) and carbon monoxide (CO) gas on rats. The experiments were designed and executed by the U.S. Army's Edgewood Chemical and Biological Center (ECBC) and the Naval Medical Research Unit Dayton (NAMRU-D) between 2012 and 2015. We conducted an independent analysis of the toxic load model's ability to predict the ECBC/NAMRU-D experimental data using an analytical methodology oriented toward hazard prediction model users. We found that although some of the proposed extensions of the toxic load model perform better than others, all of them have difficulty reproducing the experimental data. The toxic load model also has difficulty reproducing even the constant-concentration data for HCN exposures under 10 min.

Blood volume measurement using cardiovascular magnetic resonance and ferumoxytol: preclinical validation.

BACKGROUND: The hallmark of heart failure is increased blood volume. Quantitative blood volume measures are not conveniently available and are not tested in heart failure management. We assess ferumoxytol, a marketed parenteral iron supplement having a long intravascular half-life, to measure the blood volume with cardiovascular magnetic resonance (CMR). METHODS: Swine were administered 0.7 mg/kg ferumoxytol and blood pool T1 was measured repeatedly for an hour to characterize contrast agent extraction and subsequent effect on Vblood estimates. We compared CMR blood volume with a standard carbon monoxide rebreathing method. We then evaluated three abbreviated acquisition protocols for bias and precision. RESULTS: Mean plasma volume estimated by ferumoxytol was 61.9 ± 4.3 ml/kg. After adjustment for hematocrit the resultant mean blood volume was 88.1 ± 9.4 ml/kg, which agreed with carbon monoxide measures (91.1 ± 18.9 ml/kg). Repeated measurements yielded a coefficient of variation of 6.9%, and Bland-Altman repeatability coefficient of 14%. The blood volume estimates with abbreviated protocols yielded small biases (mean differences between 0.01-0.06 L) and strong correlations (r2 between 0.97-0.99) to the reference values indicating clinical feasibility. CONCLUSIONS: In this swine model, ferumoxytol CMR accurately measures plasma volume, and with correction for hematocrit, blood volume. Abbreviated protocols can be added to diagnostic CMR examination for heart failure within 8 min.

Perfusion with carbon monoxide does not affect extracellular glutamate in dialysates of the hippocampus of freely moving mice.

Carbon monoxide (CO) produces several neurological effects, including cognitive, mood, and behavioral disturbance. Glutamate is thought to play a particularly important role in learning and memory. Thus, the present study was aimed at investigating the local effect of CO on the glutamate level in the hippocampus of mice using in vivo reverse microdialysis. Mice were perfused with Ringer's solution (control) or CO (60-125 µM) in Ringer's solution into the hippocampus via microdialysis probe. Dialysate samples were collected every 20 min, and then analyzed with high-performance liquid chromatography coupled to an electrochemical detector. The result revealed that the perfusion with CO had no significant effect on glutamate levels (p = 0.316) as compared to the control group. This finding does not support a local CO rise as the cause of the increased glutamate level in the hippocampus of mice.

Modulatory Effects of Mild Carbon Monoxide Exposure in the Developing Mouse Cochlea.

Carbon monoxide (CO) is well known as a highly toxic poison at high concentrations, yet in physiologic amounts it is an endogenous biological messenger in organs such as the internal ear and brain. In this study we tested the hypothesis that chronic very mild CO exposure at concentrations 25-ppm increases the expression of oxidative stress protecting enzymes within the cellular milieu of the developing inner ear (cochlea) of the normal CD-1 mouse. In addition we tested also the hypothesis that CO can decrease the pre-existing condition of oxidative stress in the mouse model for the human medical condition systemic lupus erythematosus by increasing two protective enzymes heme-oxygenase-1 (HO-1), and superoxide dismutase-2 (SOD-2). CD-1 and MRL/lpr mice were exposed to mild CO concentrations (25 ppm in air) from prenatal only and prenatal followed by early postnatal day 5 to postnatal day 20. The expression of cell markers specific for oxidative stress, and related neural/endothelial markers were investigated at the level of the gene products by immunohistochemistry, proteomics and mRNA expression (quantitative real time-PCR). We found that in the CD-1 and MRL/lpr mouse cochlea SOD-2 and HO-1 were upregulated. In this mouse model of autoimmune disease defense mechanism are attenuated, thus mild CO exposure is beneficial. Several genes (mRNA) and proteins detected by proteomics involved in cellular protection were upregulated in the CO exposed CD-1 mouse and the MRL/lpr mouse.

The role of carbon monoxide and heme oxygenase in the prevention of sickle cell disease vaso-occlusive crises.

Sickle Cell Disease (SCD) is a painful, lifelong hemoglobinopathy inherited as a missense point mutation in the hemoglobin (Hb) beta-globin gene. This disease has significant impact on quality of life and mortality, thus a substantial medical need exists to reduce the vaso-occlusive crises which underlie the pathophysiology of the disease. The concept that a gaseous molecule may exert biological function has been well known for over one hundred years. Carbon monoxide (CO), although studied in SCD for over 50 years, has recently emerged as a powerful cytoprotective biological response modifier capable of regulating a host of physiologic and therapeutic processes that, at low concentrations, exerts key physiological functions in various models of tissue inflammation and injury. CO is physiologically generated by the metabolism of heme by the heme oxygenase enzymes and is measurable in blood. A substantial amount of preclinical and clinical data with CO have been generated, which provide compelling support for CO as a potential therapeutic in a number of pathological conditions. Data underlying the therapeutic mechanisms of CO, including in SCD, have been generated by a plethora of in vitro and preclinical studies including multiple SCD mouse models. These data show CO to have key signaling impacts on a host of metallo-enzymes as well as key modulating genes that in sum, result in significant anti-inflammatory, anti-oxidant and anti-apoptotic effects as well as vasodilation and anti-adhesion of cells to the endothelium resulting in preservation of vascular flow. CO may also have a role as an anti-polymerization HbS agent. In addition, considerable scientific data in the non-SCD literature provide evidence for a beneficial impact of CO on cerebrovascular complications, suggesting that in SCD, CO could potentially limit these highly problematic neurologic outcomes. Research is needed and hopefully forthcoming, to carefully elucidate the safety and benefits of this potential therapy across the age spectrum of patients impacted by the host of pathophysiological complications of this devastating disease.

The effect of blood volume and volume loading on left ventricular diastolic function in individuals with spinal cord injury.

STUDY DESIGN: Cohort Study (Prospective Observational Study). OBJECTIVES: The objectives of the study were (i) to examine left ventricular (LV) diastolic function at rest and during rapid saline infusion in those with spinal cord injury (SCI) and (ii) to determine the contribution of blood volume on the purported diastolic impairments in individuals with SCI. SETTINGS: St Catharines, ON, Canada. METHODS: Thirteen SCI (AIS:A-D; C4-T6; age: 41±8.5; 10 males, 3 females) and 12 able-bodied (AB) individuals (age: 40±8.5; 9 males, 3 females) without a history of cardiovascular disease participated in the study. LV structure and diastolic function were assessed via conventional echocardiography. The carbon monoxide rebreathe test was used to measure the blood volume. LV diastolic function was assessed once more following rapid saline infusion (dose: 15 ml kg-1; rate: 100 ml min-1). RESULTS: Compared with the AB group, individuals with SCI had a smaller LV internal diameter (SCI: 4.5±0.3 cm vs AB: 5.1±0.7 cm; P=0.01), lower blood volume (SCI: 3.9±0.6 l vs AB: 5.0±1.2 l; P=0.02) and end-diastolic volume (SCI: 97.2±29.4 ml vs AB: 128.6±38.3 ml; P=0.03). There were no between-group differences in baseline diastolic parameters; however, when LV internal diameter was adjusted for individuals with SCI demonstrated lower early to late transmitral velocity ratio (SCI: 1.9±0.5 vs AB: 2.2±0.7; P=0.03). There was no between-group difference in diastolic responses to the saline infusion, as both groups showed similar diastolic changes following volume loading. CONCLUSION: Individuals with SCI have preserved LV diastolic function despite having lower preload. Preserved diastolic function may be mediated by the cardiac atrophy that occurs following SCI. Individuals with SCI also demonstrate normal diastolic responses to increased volume loading, suggesting compliant ventricles.

Decreased blood pressure associated with in-vehicle exposure to carbon monoxide in Korean volunteers.

BACKGROUND: Carbon monoxide (CO) is one of the primary components of emissions from light-duty vehicles, and reportedly comprises 77% of all pollutants emitted in terms of concentration. Exposure to CO aggravates cardiovascular disease and causes other health disorders. The study was aimed to assess the negative effects by injecting different amounts of CO concentration directly to human volunteers boarding in the car. METHODS: Human volunteers were exposed to CO concentrations of 0, 33.2, and 72.4 ppm, respectively during the first test and 0, 30.3, and 48.8 ppm respectively during the second test while seated in the car. The volunteers were exposed to each concentration for approximately 45 min. After exposure, blood pressure measurement, blood collection (carboxyhemoglobin [COHb] analysis), medical interview, echocardiography test, and cognitive reaction test were performed. RESULT: In patients who were exposed to a mean concentration of CO for 72.4 ± 1.4 ppm during the first exposure test and 48.8 ± 3.7 ppm during the second exposure test, the COHb level exceeded 2%. Moreover, the diastolic blood pressure was decreased while increasing in CO concentration after exposure. The medical interview findings showed that the degree of fatigue was increased and the degree of concentration was reduced when the exposed concentration of CO was increased. CONCLUSION: Although the study had a limited sample size, we found that even a low concentration of CO flowing into a car could have a negative influence on human health, such as change of blood pressure and degree of fatigue.