The effects of amifostine and dexamethasone on brain tissue lipid peroxidation during oxygen treatment of carbon monoxide-poisoned rats

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.

Heterogeneous Diffusion Metrics Patterns in Delayed Encephalopathy After Acute Carbon Monoxide Poisoning: A Case Report

Delayed encephalopathy (DE) following acute carbon monoxide (CO) poisoning is characterized by a wide range of neurological symptoms, including akinetic mutism, cognitive impairment, and gait disturbances. Herein, we reported the case of a 61-year-old patient with DE after acute CO poisoning, who displayed heterogeneous patterns of cortical and subcortical structural integrity on diffusion tensor imaging (DTI). Four distinct patterns of diffusion tensor metrics (fractional anisotropy [FA] and mean diffusivity [MD]) were observed in the patient compared to age-matched controls (a decrease in FA and an increase in MD, a decrease in FA only, an increase in MD only, and an increase in FA and MD). This study revealed heterogeneous patterns of cortical and subcortical damage associated with DE after CO poisoning, contributing to a deeper understanding of the diverse clinical symptoms observed in this patient.

The Efficacy of N-Butylphthalide and Dexamethasone Combined with Hyperbaric Oxygen on Delayed Encephalopathy After Acute Carbon Monoxide Poisoning

Background

Carbon monoxide (CO) poisoning is a common health problem among people in many countries, primarily because of its severe clinical effects and high toxicological morbidity and mortality. Acute brain injury and delayed encephalopathy after acute carbon monoxide poisoning (DEACMP) are the most common neurological complications. This study was performed to assess the efficacy of N-butylphthalide (NBP) and dexamethasone (DXM) combined with hyperbaric oxygen (HBO) in patients with DEACMP.

Patients and Methods

A total of 171 patients with DEACMP were recruited and assigned to the combined therapy group (receiving NBP and DXM 5 mg/day plus HBO therapy) or the control group (HBO therapy as monotherapy). Conventional treatments were provided for all patients. The cognition and movement changes in patients were evaluated by the Mini-Mental State Examination (MMSE), the Montreal Cognitive Assessment (MoCA) scale and the Barthel index of activities of daily living (ADL) before and after the treatment at 1 month, 3 months, and 1 year, respectively.

Results

At 1 month, 3 months, and 1 year after the treatment, the MMSE, MoCA and ADL scores were all significantly higher in the combined therapy group than those in the control group. There were no significant alterations in blood glucose, blood lipids, or liver and kidney function during the whole treatment session. Some patients experienced loss of appetite, mild headache and minor skin irritations. However, these patients recovered by themselves and needed no additional medications or special treatment.

Conclusion

These results indicated that NBP and DXM combined with HBO for the treatment of DEACMP can significantly improve the cognitive and motor functions of patients and is very safe.

After Treatment with Methylene Blue is Effective against Delayed Encephalopathy after Acute Carbon Monoxide Poisoning

Delayed encephalopathy after acute carbon monoxide (CO) poisoning (DEACMP) is the most severe and clinically intractable complication that occurs following acute CO poisoning. Unfortunately, the mechanism of DEACMP is still vague. Growing evidence indicates that delayed cerebral damage after CO poisoning is related to oxidative stress, abnormal neuro-inflammation, apoptosis and immune-mediated injury. Our recent report indicated that methylene blue (MB) may be a promising therapeutic agent in the prevention of neuronal cell death and cognitive deficits after transient global cerebral ischaemia (GCI). In this study, we aimed to investigate the potential of MB therapy to ameliorate the signs and symptoms of DEACMP. Rats were exposed to 1000 ppm CO for 40 min. in the first step; CO was then increased to 3000 ppm, which was maintained for another 20 min. The rats were implanted with 7-day release Alzet osmotic mini-pumps subcutaneously under the back skin, which provided MB at a dose of 0.5 mg/kg/day 1 hr after CO exposure. The results showed that MB significantly suppressed oxidative damage and expression of pro-inflammatory factors, including tumour necrosis factor-α and interleukin (IL)-1β. MB treatment also suitably modulated mitochondrial fission and fusion, which is helpful in the preservation of mitochondrial function. Furthermore, MB dramatically attenuated apoptosis and neuronal death. Lastly, behavioural studies revealed that MB treatment preserved spatial learning and memory in the Barnes maze test. Our findings indicated that MB may have protective effects against DEACMP.

Carbon Monoxide Poisoning: Pathogenesis, Management, and Future Directions of Therapy

Carbon monoxide (CO) poisoning affects 50,000 people a year in the United States. The clinical presentation runs a spectrum, ranging from headache and dizziness to coma and death, with a mortality rate ranging from 1 to 3%. A significant number of patients who survive CO poisoning suffer from long-term neurological and affective sequelae. The neurologic deficits do not necessarily correlate with blood CO levels but likely result from the pleiotropic effects of CO on cellular mitochondrial respiration, cellular energy utilization, inflammation, and free radical generation, especially in the brain and heart. Long-term neurocognitive deficits occur in 15-40% of patients, whereas approximately one-third of moderate to severely poisoned patients exhibit cardiac dysfunction, including arrhythmia, left ventricular systolic dysfunction, and myocardial infarction. Imaging studies reveal cerebral white matter hyperintensities, with delayed posthypoxic leukoencephalopathy or diffuse brain atrophy. Management of these patients requires the identification of accompanying drug ingestions, especially in the setting of intentional poisoning, fire-related toxic gas exposures, and inhalational injuries. Conventional therapy is limited to normobaric and hyperbaric oxygen, with no available antidotal therapy. Although hyperbaric oxygen significantly reduces the permanent neurological and affective effects of CO poisoning, a portion of survivors still have substantial morbidity. There has been some early success in therapies targeting the downstream inflammatory and oxidative effects of CO poisoning. New methods to directly target the toxic effect of CO, such as CO scavenging agents, are currently under development.

Combined application of dexamethasone and hyperbaric oxygen therapy yields better efficacy for patients with delayed encephalopathy after acute carbon monoxide poisoning

Background

Delayed encephalopathy after acute carbon monoxide (CO) poisoning (DEACMP) commonly occurs after recovering from acute CO poisoning. This study was performed to assess the efficacy of the combined application of dexamethasone and hyperbaric oxygen (HBO) therapy in patients with DEACMP.

Patients and methods

A total of 120 patients with DEACMP were recruited and randomly assigned into the experimental group (receiving dexamethasone 5 mg/day or 10 mg/day plus HBO therapy) and control group (HBO therapy as monotherapy). Meanwhile, the conventional treatments were provided for all the patients. We used the Mini-Mental State Examination (MMSE) scale to assess the cognitive function, the National Institutes of Health Stroke Scale (NIHSS) to assess the neurological function and the remission rate (RR) to assess the clinical efficacy. Myelin basic protein (MBP) in the cerebrospinal fluid (CSF) was also measured.

Results

After 4 weeks of treatment, compared to the control group, the experimental group had a significantly higher remission rate (P=0.032), a significantly higher average MMSE score (P=0.037) and a significantly lower average NIHSS score (P=0.002). Meanwhile, there was a trend toward better improvement with dexamethasone 10 mg/day, and the level of MBP in the CSF of patients was significantly lower in the experimental group than in the control group (P<0.0001). The addition of dexamethasone did not significantly increase the incidence of adverse events.

Conclusion

These results indicate that the combined application of dexamethasone and HBO therapy could yield better efficacy for patients with DEACMP and should be viewed as a potential new therapy.

Structural and functional damages of whole body ionizing radiation on rat brain homogenate membranes and protective effect of amifostine

PURPOSE

To investigate the effects of whole body ionizing radiation at a sublethal dose on rat brain homogenate membranes and the protective effects of amifostine on these systems at molecular level.

MATERIALS AND METHODS

Sprague-Dawley rats, in the absence and presence of amifostine, were whole-body irradiated at a single dose of 8 Gy and decapitated after 24 h. The brain homogenate membranes of these rats were analyzed using Fourier Transform Infrared (FTIR) spectroscopy.

RESULTS

Ionizing radiation caused a significant increase in the lipid to protein ratio and significant decreases in the ratios of olefinic = CH/lipid, CH₂/lipid, carbonyl ester/lipid and CH₃/lipid suggesting, respectively, a more excessive decrease in the protein content and the degradation of lipids as a result of lipid peroxidation. In addition, radiation changed the secondary structure of proteins and the status of packing of membrane lipid head groups. Furthermore, it caused a decrease in lipid order and an increase in membrane fluidity. The administration of amifostine before ionizing radiation inhibited all the radiation-induced alterations in brain homogenate membranes.

CONCLUSIONS

The results revealed that whole body ionizing radiation at a sublethal dose causes significant alterations in the structure, composition and dynamics of brain homogenate membranes and amifostine has a protective effect on these membranes.

Diffusion tensor imaging for predicting the clinical outcome of delayed encephalopathy of acute carbon monoxide poisoning

OBJECTIVE

The aim of the present study was to determine the relationship between neuropsychiatric outcomes and diffusion tensor imaging (DTI) in patients with delayed encephalopathy after acute carbon monoxide poisoning (DEACMP).

METHODS AND MATERIALS

66 patients and 60 healthy controls were included in this study. Median fractional anisotropy (FA) of the white matter (WM) bilaterally was compared between patients and healthy controls. The Glasgow Outcome Scale (GOS) was assessed at 4-6 months following DEACMP. The association between the GOS score and FA variables was explored using the Spearman rank correlation.

RESULTS

The FA values in WM were reduced in patients with DEACMP compared with those in the volunteers. Of the 66 patients, 21 (31.8%) achieved a good outcome (GOS-5), 26 (36.4%) had moderate disability (GOS-4), 14 (21.2%) had severe disability (GOS-3), 5 (7.6%) were in a vegetative state (GOS-2), and none of the patients died (GOS-1). The FA values in the WM in patients with DEACMP correlated significantly with GOS.

CONCLUSION

DTI may be a valuable tool for assessing the severity of brain injury and may be a predictor of outcome in patients with delayed encephalopathy of acute carbon monoxide poisoning. DTI may be a valuable tool for assessing the severity of tissue injury and may be a predictor of outcome.

Amifostine, a radioprotectant agent, protects rat brain tissue lipids against ionizing radiation induced damage: an FTIR microspectroscopic imaging study

Amifostine is the only approved radioprotective agent by FDA for reducing the damaging effects of radiation on healthy tissues. In this study, the protective effect of amifostine against the damaging effects of ionizing radiation on the white matter (WM) and grey matter (GM) regions of the rat brain were investigated at molecular level. Sprague-Dawley rats, which were administered amifostine or not, were whole-body irradiated at a single dose of 800 cGy, decapitated after 24 h and the brain tissues of these rats were analyzed using Fourier transform infrared microspectroscopy (FTIRM). The results revealed that the total lipid content and CH(2) groups of lipids decreased significantly and the carbonyl esters, olefinic=CH and CH(3) groups of lipids increased significantly in the WM and GM after exposure to ionizing radiation, which could be interpreted as a result of lipid peroxidation. These changes were more prominent in the WM of the brain. The administration of amifostine before ionizing radiation inhibited the radiation-induced lipid peroxidation in the brain. In addition, this study indicated that FTIRM provides a novel approach for monitoring ionizing radiation induced-lipid peroxidation and obtaining different molecular ratio images can be used as biomarkers to detect lipid peroxidation in biological systems.

Ischemia-modified albumin levels in carbon monoxide poisoning

OBJECTIVES

Ischemia-modified albumin (IMA) is an emerging diagnostic biomarker for many ischemic conditions. This study was conducted to investigate whether there is a change in IMA levels in carbon monoxide (CO) poisoning and, if so, the clinical relevance of IMA levels.

METHODS

This cohort study, performed between November 2008 and April 2009, compared the serum IMA levels of 33 CO-poisoned patients taken at the time of presentation at the emergency department and after 3 hours of treatment and 49 healthy controls. In addition, IMA and carboxyhemoglobin levels were analyzed according to CO poisoning patients' poisoning severity scores.

RESULTS

Carbon monoxide patients' IMA levels were higher than those of the control group both at time of admission and at the third hour of the treatment, P < .0001. A significant fall was determined in carboxyhemoglobin (CO-Hb) levels at the end of the third hour of treatment, P < .0001. However, there was no significant difference between the IMA levels measured at admission and at the end of the third hour of treatment (P > .05). There was no significant correlation between IMA and CO-Hb levels in CO-poisoned patients. Also, there was no difference in blood IMA levels in classification according to patients' poisoning severity score and CO-Hb levels.

CONCLUSION

Results from this pioneering study established a high level of IMA in CO-poisoned patients, suggesting that IMA may also be sensitive to hypoxia. Considering the preliminary nature of this study, the clinical utility of IMA levels in CO poisoning should be further investigated with more comprehensive studies.

Amifostine (WR2721) confers DNA protection to in vivo cisplatin-treated murine peripheral blood leukocytes

Amifostine [S-2-3-aminopropyl amino ethyl phosphorotioic acid], a modulator agent for antineoplastic drugs involved in free radicals generation has given controversial results in cisplatin treated leukocytes in vitro. We have evaluated the amifostine protection over leukocytes in vivo, using comet assay. Groups of five OF1 male mice were given one of three doses of amifostine (56, 105 and 200 mg/Kg) after a cisplatin single injection (10 mg/Kg). Serum malonyldialdehyde levels, catalase and superoxide dismutase activity were also evaluated. Amifostine showed significant DNA protection (p< 0.01) at the two lower doses evaluated. Malonyldialdehyde decreased in all amifostine treatments with respect to cisplatin while antioxidant enzyme activities remained unchanged. However, DNA migration increased with the highest amifostine dose; in fact highest dose of amifostine did no protect damage caused by cisplatin this result have implications on amifostine treatment schedules in clinical practice.