Development of a risk prediction nomogram for delayed neuropsychiatric sequelae in patients with acute carbon monoxide poisoning.

OBJECTIVES: Delayed neuropsychiatric sequelae (DNS) are critical complications following acute carbon monoxide (CO) poisoning that can substantially affect the patient's life. Identifying high-risk patients for developing DNS may improve the quality of follow-up care. To date, the predictive DNS determinants are still controversial. Consequently, this study aimed to construct a practical nomogram for predicting DNS in acute CO-poisoned patients. METHODS: This retrospective study was conducted on patients with acute CO poisoning admitted to the Tanta University Poison Control Center (TUPCC) from December 2018 to December 2022. Demographic, toxicological, and initial clinical characteristics data, as well as laboratory investigation results, were recorded for the included patients. After acute recovery, patients were followed up for six months and categorized into patients with and without DNS. RESULTS: Out of 174 enrolled patients, 38 (21.8%) developed DNS. The initial Glasgow Coma Scale (GCS), carboxyhemoglobin (COHb) level, CO exposure duration, oxygen saturation, PaCO2, and pulse rate were significantly associated with DNS development by univariate analysis. However, the constructed nomogram based on the multivariable regression analysis included three parameters: duration of CO exposure, COHb level, and GCS with adjusted odd ratios of 1.453 (95% CI: 1.116-1.892), 1.262 (95% CI: 1.126-1.415), and 0.619 (95% CI: 0.486-0.787), respectively. The internal validation of the nomogram exhibited excellent discrimination (area under the curve [AUC] = 0.962), good calibration, and satisfactory decision curve analysis for predicting the DNS probability. CONCLUSIONS: The proposed nomogram could be considered a simple, precise, and applicable tool to predict DNS development in acute CO-poisoned patients.

Detection and clinical application of red blood cell survival. / çº¢ç»†èƒžå¯¿å‘½çš„æ£€æµ‹åŠå ¶ä¸´åºŠåº”ç”¨.

There are 2 techniques for detecting red blood cell survival (RBCS) detection techniques: red blood cell labeling test and carbon monoxide (CO) breath test. The former has disadvantages such as long measurement times and complicated procedures, while the latter is simple, convenient, moderately priced, and capable of dynamically monitoring changes in RBCS before and after treatment. Currently, the CO breath test is gradually being implemented in clinical practice. RBCS is not only applied to hematologic diseases such as multiple myeloma, myelodysplastic syndromes, lymphoma, and thalassemia, but also to non-hematologic diseases like type 2 diabetes and chronic kidney disease. It can assist in diagnosis, guide treatment, evaluate drug treatment efficacy, and predict disease progression.

CARDIOGENIC SHOCK AND GLOBUS PALLIDUS INJURY AS A PRESENTATION OF CARBON MONOXIDE POISONING.

Carbon monoxide poisoning is one of the leading causes of mortality and morbidity by poisoning in the world. Signs and symptoms are nonspecific and related to impaired oxygen delivery to tissues, with the brain being the most affected organ due to its high oxygen demand. CO-Hb is a poor indicator of severity and long-term outcome, with clinicians relying more on clinical features such as level of consciousness and need for intubation, organ dysfunction and shock and also pH level. A 45-year-old female was found unconscious in her home with the fireplace lit and smoke all over the house. She was last seen well 18 hours before. She was brought to the emergency department and was admitted to the ICU in coma and cardiogenic shock, with a metabolic acidosis with hyperlactacidemia and a CO-Hb level of 15.5%. Laboratorial investigation revealed hepatic cytolysis, acute renal failure, rhabdomyolysis and a troponin I level of 338 ng/L. ECG showed no acute myocardial ischemia. Echocardiogram revealed diffuse hypokinesia with an ejection fraction of 25%. Head CT scan showed bilateral and symmetrical hypodensities of the globus pallidus. The patient underwent hyperbaric oxygen treatment with full neurological and cardiac recovery, allowing extubation 48 hours after admission. This rare severe case of coma due to carbon monoxide intoxication with globus pallidus injury and cardiogenic shock was successfully treated with hyperbaric oxygen, showing that it can be the right treatment choice in these cases, with an excellent impact on neurological and cardiac outcome.

L'intoxication au CO est une des causes principales de décès par empoisonnement dans le monde. Les signes, non spécifiques, sont dus à l'hypoxie cellulaire et le cerveau est le plus souvent atteint en raison de sa consommation d'oxygène élevée. Le taux d'HbCO est un indice peu fiable de la gravité initiale et du risque de séquelles si bien que l'on préfère se baser sur la clinique (conscience, nécessité d'intubation, dysfonctions d'organe, choc) et le pH sanguin. Une femme de 45 ans a été trouvée inconsciente à son domicile entièrement enfumé, cheminée allumée. Le dernier contact remontait à 18 heures. Elle a été hospitalisée en réanimation en coma et choc cardiogénique, avec une acidose lactique et une HbCO à 15,5%. La biologie retrouvait une cytolyse hépatique, une insuffisance rénale aiguë, une rhabdomyolyse et une troponine I à 338 ng/L. L'ECG ne trouvait pas d'ischémie, l'échocardiographie objectivait une hypokinésie globale et évaluait la fraction d'éjection à 25%. La TDM cérébrale montrait une hypodensité pallidale bilatérale. L'oxygénothérapie hyperbare (OHB) a permis une récupération neurologique et cardiaque complètes, permettant l'extubation à h48. Cette récupération complète après OHB confirme qu'il peut s'agir du traitement idoine des intoxications graves au CO, avec un excellent impact sur les devenirs cardiaque et neurologique.

High-performance CO detection based on a PhC cavity in terahertz band.

Combined with the light absorption from molecular vibration, photonic crystal (PhC) cavity structures have gradually shown great potential in gas detection, particularly for toxic gases. We proposed a PhC cavity with a high-quality factor of 1.24 × 106 and a small mode volume of 2.3 × 10-4 (λ/n)3, which was used for carbon monoxide detection. To reduce the interference of other gases, we set the resonance frequency in the terahertz band. The numerical analysis shows that the structure has good selectivity and high sensitivity, and the linear fitting of the results provides the possibility to realize the application, which has great competitiveness in the same type of sensor structure. Additionally, we also proved that the interference of H2O and CO2 on the CO sensing can be ignored, and it supports the detection of CO without pre-drying.

Risk of lung diseases in patients with previous carbon monoxide poisoning: a nationwide population-based cohort study in the Republic of Korea.

INTRODUCTION: Carbon monoxide poisoning is associated with severe damage to various organs. In this study, we aimed to determine if previous carbon monoxide poisoning was associated with an increased risk of lung diseases. METHODS: The study population was derived from the National Health Insurance Service database of Korea between 1 January 2002 and 31 December 2021. Adults with carbon monoxide poisoning, with at least one visit to medical facilities between 2002 and 2021, were included. For comparison, an equal number of matched controls with the same index date were selected from the database. RESULTS: A total of 28,618 patients with carbon monoxide poisoning and 28,618 matched controls were included in this study. Approximately 42.8 per cent of the patient and control groups were female, with a mean age of 51.3 years. In patients with carbon monoxide poisoning, there was a significant increase in the risk of lung cancer (adjusted hazard ratio, 1.84; 95 per cent confidence interval, 1.42-2.39; P < 0.001), chronic obstructive pulmonary disease (adjusted hazard ratio, 1.60; 95 per cent confidence interval, 1.36-1.89; P < 0.001), pulmonary tuberculosis (adjusted hazard ratio, 1.46; 95 per cent confidence interval, 1.13-1.88; P = 0.003), and non-tuberculous mycobacterial infection (adjusted hazard ratio, 1.54; 95 per cent confidence interval, 1.01-2.36; P = 0.047). DISCUSSION: In this retrospective cohort study, previous carbon monoxide poisoning was associated with an increased risk of lung cancer, chronic obstructive pulmonary disease, pulmonary tuberculosis, and non-tuberculous mycobacterial infection. Further studies are needed to confirm such an association in other populations and the risk of lung diseases due to the toxic effect of carbon monoxide from different sources. CONCLUSIONS: Previous carbon monoxide poisoning was associated with an increased risk of lung diseases, but the relative importance of the causes and sources of exposure was not known. The long-term management of survivors of acute carbon monoxide poisoning should include monitoring for lung cancer, chronic obstructive pulmonary disease, pulmonary tuberculosis, and non-tuberculous mycobacterial infection.

Short and long-term outcomes of multidimensional physiotherapy in cases with acute compartment syndrome secondary to carbon monoxide poisoning with prolonged forearm compression.

BACKGROUND: Compartment syndrome following carbon monoxide (CO) poisoning and compression, can have a devastating impact on neuromuscular structures, depending on a time-based dosage. PURPOSE: To investigate multidimensional physiotherapy's short-term and long-term outcomes in identical twin cases who developed compartment syndrome due to CO poisoning and prolonged compression. STUDY DESIGN: Case report. METHODS: This study was conducted with two male cases, a 21-year-old identical twin. The loss of consciousness due to CO poisoning lasted for 15 hours. Case one had compartment syndrome that caused damage to the median and ulnar nerves in the right forearm, while Case two had compartment syndrome that caused damage to the radial nerve in the left forearm. No surgical intervention was performed (Fasciotomy etc). RESULTS: The disability, dexterity, hand health status, sensory-motor function, and edema were evaluated. Initial evaluations showed severe sensory and motor dysfunction, disability, and edema. Treatment included Complex decongestive physiotherapy, electrical stimulation, therapeutic ultrasound, orthotics, and exercises. On the 144th day (discharge day), both cases still exhibited weakness in functional strength and sensory loss compared to the uninjured side. At the ninth month, all parameters except strength were similar to the uninjured side in both cases. By the 53rd month, strength also reached normal values. CONCLUSIONS: Multidimensional physiotherapy effectively manages edema, improves sensory-motor function, and enhances hand function in the short and long term.

CoCorrole-Functionalized PCN-222 for Carbon Monoxide Selective Adsorption.

The high risk of CO poisoning justifies the need for indoor air quality control and warning systems based on the detection of low concentrations (ppm-ppb) of CO. Cobalt corrole complexes selectively bind CO vs. O2, CO2, N2, opening new fields of applications. By combining the CO chemisorption properties of cobalt corroles with the known sorption capacity of MOFs, we hope to obtain high performance sensing materials for CO detection. In addition, the exposed metal sites of MOFs lead to CO2 physisorption, allowing the co-detection of CO and CO2. In this work, PCN-222 a stable Zr-based MOF made from Ni(TCPP) with natural vacancies has been used as a porous matrix for the grafting of electron-poor metallocorroles. The materials were characterized by powder XRD, SEM and optical microscopy, BET analyses and gas adsorption measurements at 298 K. No degradation of the crystalline structure of PCN-222 was observed. At 1 atm, the adsorbed CO(g) volumes measured for the best materials were 12.15 cm3 g-1 and 14.01 cm3 g-1 for CoCorr2@PCN-222 and CoCorr3@PCN-222 respectively, and both materials exhibited high CO chemisorption and selectivity against O2, N2, and CO2 at low pressure due to the highest energy of the chemisorption process vs physisorption. (198 Words).

Real-time evolution characteristics and potential reactions of contaminants in commuter bus cabin air.

Despite the increasing use of motor vehicles, the impact of airborne pollutants and their health risks inside public transportation, such as commuter buses, is not well understood. This study assessed air quality inside an urban commuter bus by continuously monitoring PM10, PM2.5, and CO concentrations during both driving and parking periods. Our findings revealed that the ventilation system of the bus significantly reduced the infiltration of outdoor particulate matter and water vapor. However, CO concentrations were considerably higher inside the bus than outside, primarily due to vehicular self-emission. The ineffection of the ventilation system to remove CO potentially increases long-term exposure risks for passengers. The study identified ozone as a key oxidant in the cabin. Besides vehicle emissions, C3-C10 saturated aldehydes and carbonyl compounds were detected, including acetone, propanal, and hexanal. The presence of 6-MHO, an oxidation product of squalene, suggests that passengers contribute to VOCs load through direct emissions or skin surface reactions. Additionally, human respiration was found to significantly contribute to isoprene levels, estimated at 81.7 %. This research underscores the need for further investigation into the cumulative effects of stable compounds in cabin air and provides insights for developing healthier public transportation systems.

Opportunities for Insight into the Mechanism of Efficient CO2/CO Interconversion at a Nickel-Iron Cluster in CO Dehydrogenase.

The reduction of CO2 with low overpotential and high selectivity is a crucial challenge in catalysis. Fortunately, natural systems have evolved enzymes that achieve this catalytic reaction very efficiently at a complex nickel-iron-sulfur cluster within carbon monoxide dehydrogenase (CODH). Extensive biochemical, crystallographic, and spectroscopic work has been done to understand the structures and mechanism involved in the catalytic cycle, which are summarized here from the perspective of mechanistic organometallic chemistry. We highlight the ambiguities in the data and suggest experiments that could lead to clearer understanding of the mechanism and structures of intermediates at the active-site cluster. These include parallel crystallography and spectroscopy, as well as the preparation of synthetic analogues that help to interpret structural and spectroscopic signatures.

Customizing pyridinic nitrogen coordination in Ni-N-C for electrocatalytic CO2reduction towards CO.

Nickel anchored N-doped carbon electrocatalysts (Ni-N-C) are rapidly developed for the electrochemical reduction reaction of carbon dioxide (CO2RR). However, the high-performanced Ni-N-C analogues design for CO2RR remains bewilderment, for the reason lacking of definite guidance for its structure-activity relationship. Herein, the correlation between the proportion of nitrogen species derived from various nitrogen sources and the CO2RR activity of Ni-N-C is investigated. The X-ray photoelectron spectroscopy (XPS) spectrum combined with the CO2RR performance results show that pyridinic-N content has a positive correlation with CO2RR activity. Moreover, density functional theory (DFT) demonstrates that pyridinic-N coordinated Ni-N4 sites offers optimized free energy and favorable selectivity towards CO2RR compared with pyrrolic-N. Accordingly, Ni-Na-C with highest pyridinic-N content (ammonia as nitrogen source) performs superior CO2RR activity, with the maximum carbon monoxide faradaic efficiency (FECO) of 99.8% at -0.88 V vs. RHE and the FECO surpassing 95% within potential ranging of -0.88 to -1.38 V vs. RHE. The building of this parameter for CO2RR activity of Ni-N-C give instructive forecast for low-cost and highly active CO2RR electrocatalysts. .

Carbon monoxide-releasing Vehicle CO@TPyP-FeMOFs modulating macrophages phenotype in inflammatory wound healing.

Healing of chronic wounds has been critically limited by prolonged inflammation. Carbon monoxide (CO) is a biologically active molecule with high potential based on its efficacy in modulating inflammation, promoting wound healing and tissue remodeling. Strategies to use CO as a gaseous drug to chronic wounds have emerged, but controlling the sustained release of CO at the wound site remains a major challenge. In this work, a porphyrin-Fe based metal organic frameworks, TPyP-FeMOFs was prepared. The synthesized TPyP-FeMOFs was high-temperature vacuum activated (AcTPyP-FeMOFs) and AcTPyP-FeMOFs had a relatively high Fe (II) content. CO sorption isotherms showed that AcTPyP-FeMOFs chemisorbed CO and thus CO release was sustained and prolonged. In vitro evaluation results showed that CO@TPyP-FeMOFs reduced the inflammatory level of lipopolysaccharide (LPS) activated macrophages, polarized macrophages to M2 anti-inflammatory phenotype, and promoted the proliferation of fibroblasts by altering the pathological microenvironment. In vivo study confirmed CO@TPyP-FeMOFs promoted healing in a LPS model of delayed cutaneous wound repair and reduced macrophages and neutrophils recruitment. Both in vitro and in vivo studies verified that CO@TPyP-FeMOFs acted on macrophages by modulating phenotype and inflammatory factor expression. Thus, CO release targeting macrophages and pathological microenvironment modulation presented a promising strategy for wound healing.

Forensic utility of carboxyhemoglobin levels in postmortem spleen specimens in South Korea.

In order to determine whether CO poisoning was the definitive cause of death, the concentration of carboxyhemoglobin (COHb) in spleen specimens was analyzed using a gas chromatography-thermal conductivity detector. 125 cases of forensic autopsy reports containing COHb analysis requests were analyzed and subdivided into two groups, improbable and highly probable of CO intoxication. In the first group which consists of 100 cases, the results of COHb analysis were negative, and the circumstances of death, as well as the postmortem findings could not validate the exposure to CO. In the second group which consists of 25 cases, the results of COHb were positive, and both postmortem findings and circumstances of death confirmed the exposure to CO. In the cases of indoors and vehicle fires or those including the use of briquettes, COHb levels reached 43.1-97.5 %, whereas in individuals without any feature of CO poisoning had COHb level high as 29.8 %. However, certain cases without any connection to fire nor CO exposure also contained significant amount of CO based on post-mortem analysis. This study focuses on cases without any relationship to fire or CO and proves that COHb levels below 30 % may be considered as a contributing factor to but not exclusively as the cause of death.

Self-assembled carbon monoxide nanogenerators managing sepsis through scavenging multiple inflammatory mediators.

Sepsis, a life-threatening syndrome of organ damage resulting from dysregulated inflammatory response, is distinguished by overexpression of inflammatory cytokines, excessive generation of reactive oxygen/nitrogen species (RONS), heightened activation of pyroptosis, and suppression of autophagy. However, current clinical symptomatic supportive treatment has failed to reduce the high mortality. Herein, we developed self-assembled multifunctional carbon monoxide nanogenerators (Nano CO), as sepsis drug candidates, which can release CO in response to ROS, resulting in clearing bacteria and activating the heme oxygenase-1/CO system. This activation strengthened endogenous protection and scavenged multiple inflammatory mediators to alleviate the cytokine storm, including scavenging RONS and cfDNA, inhibiting macrophage activation, blocking pyroptosis and activating autophagy. Animal experiments show that Nano CO has a good therapeutic effect on mice with LPS-induced sepsis, which is manifested in hypothermia recovery, organ damage repair, and a 50% decrease in mortality rates. Taken together, these results illustrated the efficacy of multifunctional Nano CO to target clearance of multiple mediators in sepsis treatment and act against other refractory inflammation-related diseases.

Brain carbon monoxide can suppress the rat micturition reflex through brain γ-aminobutyric acid receptors.

OBJECTIVES: To investigate roles of brain carbon monoxide (CO), an endogenous gasotransmitter, in regulation of the rat micturition reflex. METHODS: In urethane-anesthetized (0.8 g/kg, ip) male rats, evaluation of urodynamic parameters was started 1 h before intracerebroventricular administration of CORM-3 (CO donor) or ZnPP (non-selective inhibitor of heme oxygenase, a CO producing enzyme) and continued for 2 h after the administration. We also investigated effects of centrally pretreated SR95531 (GABAA receptor antagonist) or SCH50911 (GABAB receptor antagonist) on the CORM-3-induced response. RESULTS: CORM-3 significantly prolonged intercontraction intervals (ICIs) without changing maximal voiding pressure (MVP), while ZnPP significantly shortened ICI and reduced single-voided volume and bladder capacity without affecting MVP, post-voided residual volume, or voiding efficiency. The ZnPP-induced ICI shortening was reversed by CORM-3. The CORM-3-induced ICI prolongation was significantly attenuated by centrally pretreated SR95531 or SCH50911, respectively. CONCLUSIONS: Brain CO can suppress the rat micturition reflex through brain γ-aminobutyric acid (GABA) receptors.

Analysis of factors associated with the development of delayed encephalopathy following acute carbon monoxide poisoning.

In this study, we analyzed the factors influencing the development of delayed encephalopathy in patients with acute carbon monoxide poisoning (ACOP) (DEACMP) following conventional treatment such as hyperbaric oxygen therapy (HBOT). Between January 2012 and January 2022, we retrospectively analyzed 775 patients with ACOP, who were admitted to the Second Department of Rehabilitation Medicine and received HBOT in the Second Hospital of Hebei Medical University. These patients were divided into the non-DEACMP and DEACMP groups based on their follow-up; we then compared the general data, clinical characteristics, admission examination, and treatment between the two groups to identify risk factors for the development of DEACMP. The DEACMP group comprised of 168 cases, while the non-DEACMP group consisted of 607 cases. Univariate analysis showed that there were 20 possible prognostic factors in the non-DEACMP and DEACMP groups. The results of multivariable regression analyses suggested that the occurrence of DEACMP was significantly correlated with advanced age, the combination of multiple medical histories, the duration of CO exposure, the duration of coma, poisoning degree, the Interval between ACOP and the first HBOT, the total number of HBOTs, and the combination with rehabilitation treatment. DEACMP patients who are older, have more comorbidities, prolonged CO exposure, prolonged coma, severe intoxication, long intervals between ACOP and the first HBOT, fewer HBOT treatments, and who are not treated with a combination of rehabilitative therapies have a poor prognosis.

Does Exposure to Ambient Air Pollution Affect Gestational Age and Newborn Weight?-A Systematic Review.

Current evidence suggests that airborne pollutants have a detrimental effect on fetal growth through the emergence of small for gestational age (SGA) or term low birth weight (TLBW). The study's objective was to critically evaluate the available literature on the association between environmental pollution and the incidence of SGA or TLBW occurrence. A comprehensive literature search was conducted across Pubmed/MEDLINE, Web of Science, Cochrane Library, EMBASE, and Google Scholar using predefined inclusion and exclusion criteria. The methodology adhered to the PRISMA guidelines. The systematic review protocol was registered in PROSPERO with ID number: CRD42022329624. As a result, 69 selected papers described the influence of environmental pollutants on SGA and TLBW occurrence with an Odds Ratios (ORs) of 1.138 for particulate matter ≤ 10 µm (PM10), 1.338 for particulate matter ≤ 2.5 µm (PM2.5), 1.173 for ozone (O3), 1.287 for sulfur dioxide (SO2), and 1.226 for carbon monoxide (CO). All eight studies analyzed validated that exposure to volatile organic compounds (VOCs) is a risk factor for SGA or TLBW. Pregnant women in the high-risk group of SGA occurrence, i.e., those living in urban areas or close to sources of pollution, are at an increased risk of complications. Understanding the exact exposure time of pregnant women could help improve prenatal care and timely intervention for fetuses with SGA. Nevertheless, the pervasive air pollution underscored in our findings suggests a pressing need for adaptive measures in everyday life to mitigate worldwide environmental pollution.

Differential diagnosis and prognosis of delayed neuropsychiatric sequelae after acute carbon monoxide poisoning in a patient with schizophrenia: A case report.

Background: Delayed neuropsychiatric sequelae (DNS) is a syndrome that appears days to weeks after acute carbon monoxide (CO) poisoning. DNS shows various neuropsychiatric symptoms, such as mental deterioration and parkinsonism. Case Presentation: Our case was a 37-year-old male with schizophrenia. He attempted suicide by CO poisoning and was brought to our emergency department (Day 0). He was ventilated with normobaric oxygen therapy for 3 days and moved to the psychiatric ward with clear consciousness. We restarted antipsychotics, and he gradually presented akinesia and rigidity. Additionally, around Day 32, he showed disorganized behaviors, mental deterioration, incontinence, and gait disturbance. Brain magnetic resonance imaging (MRI) showed slightly abnormal findings on Day 35. Although we suspected DNS on the clinical course and the MRI findings, catatonia and side-effects of antipsychotics were also considered. Finally, electroencephalography (EEG) on Day 38 with apparent abnormalities, including diffuse slow waves, resulted in our diagnosis of DNS, and he underwent hyperbaric oxygen therapy. His condition was dramatically improved, and his diffuse slow waves on EEG disappeared on Day 83. We also followed his clinical presentations and brain MRI until 33 months. Throughout the whole follow-up, his cognition, movement, and psychiatric symptoms remained stable. However, his brain MRI showed progressive atrophy in bilateral frontal lobes and increasing white matter lesions throughout the whole course. Conclusion: EEG, as well as brain MRI, may be crucial in the differential diagnosis of DNS in patients with complex conditions involving medications and severe mental illnesses.

An alcove at the acetyl-CoA synthase nickel active site is required for productive substrate CO binding and anaerobic carbon fixation.

One of seven natural CO2 fixation pathways, the anaerobic Wood-Ljungdahl Pathway (WLP) is unique in generating CO as a metabolic intermediate, operating through organometallic intermediates, and in conserving (versus utilizing) net ATP. The key enzyme in the WLP is acetyl-CoA synthase (ACS), which uses an active site [2Ni-4Fe-4S] cluster (A-cluster), a CO tunnel, and an organometallic (Ni-CO, Ni-methyl, and Ni-acetyl) reaction sequence to generate acetyl-CoA. Here we reveal that an alcove, which interfaces the tunnel and the A-cluster, is essential for CO2 fixation and autotrophic growth by the WLP. In vitro spectroscopy, kinetics, binding, and in vivo growth experiments reveal that a Phe229A substitution at one wall of the alcove decreases CO affinity thirty-fold and abolishes autotrophic growth; however, a F229W substitution enhances CO binding 80-fold. Our results indicate the structure of the alcove is exquisitely tuned to concentrate CO near the A-cluster; protect ACS from CO loss during catalysis, provide a haven for inhibitory CO, and stabilize the tetrahedral coordination at the Nip site where CO binds. The directing, concentrating, and protective effects of the alcove explain the inability of F209A to grow autotrophically. The alcove also could help explain current controversies over whether ACS binds CO and methyl through a random or ordered mechanism. Our work redefines what we historically refer to as the metallocenter "active site". The alcove is so crucial for enzymatic function that we propose it is part of the active site. The community should now look for such alcoves in all "gas handling" metalloenzymes.

Carbon Monoxide-Related Vision Loss in an Acute Burn Patient.

Carbon monoxide poisoning can occur as part of smoke exposure in the burn population. Here we report the case of a 32-year-old, previously healthy male, with carbon monoxide-related blindness after smoke exposure in an apartment fire. Cerebral hypoperfusion was diagnosed using magnetic resonance imaging of the brain, and the patient was diagnosed with cortical visual impairment. He was treated with hyperbaric oxygen therapy following which he had partial recovery of his vision. There is a paucity of information regarding this phenomenon and its treatment.