Progressive neuropsychiatric and brain abnormalities after smoke inhalation

Acute Neurobehavioral and Glial Responses to Explosion Gas Inhalation in Rats

Military personnel, firefighters, and fire survivors exhibit a higher prevalence of mental health conditions such as depression and post-traumatic stress disorder (PTSD) compared to the general population. While numerous studies have examined the neurological impacts of physical trauma and psychological stress, research on acute neurobehavioral effects of gas inhalation from explosions or fires is limited. This study investigates the early-stage neurobehavioral and neuronal consequences of acute explosion gas inhalation in Sprague-Dawley rats. Rats were exposed to simulated explosive gas and subsequently assessed using behavioral tests and neurobiological analyses. The high-dose exposure group demonstrated significant depression-like behaviors, including reduced mobility and exploration. However, neuronal damage was not evident in histological analyses. Immunofluorescence revealed increased density of radial glia and oligodendrocytes in specific brain regions, suggesting hypoxia and axon damage induced by gas inhalation as a potential mechanism for the observed neurobehavioral changes. These findings underscore the acute impact of explosion gas inhalation on mental health, highlighting the habenula and dentate gyrus of hippocampus as the possible target regions. The findings are expected to support early diagnosis and treatment strategies for brain injuries caused by explosion gas, offering insights into early intervention for depression and PTSD in affected populations.

Systemic anti-inflammatory effects of mesenchymal stem cells in burn: A systematic review of animal studies

Background

Despite the advances in burn care, severe burns still impose significant morbidity and mortality. Severe burns are associated with an inflammatory response that ranges from alterations in vital signs to shock, multiorgan failure, and death. Mesenchymal stem cells (MSCs) are known for their anti-inflammatory and immunomodulatory effects. Therefore, MSCs were investigated for their potential benefits in modulating burn-induced inflammation and organ damage in several studies.

Aim

We have conducted a systematic review of the literature to evaluate the efficacy of MSCs in modulating burn-induced systemic inflammation and organ damage in animal models.

Methods

Four databases were searched: PubMed, Cumulative Index of Nursing and Allied Health Literature, Scopus, and Web of Science. We used the Preferred Reporting Items for Systematic Reviews and Meta-Analysis as our basis of organization.

Results

Eight studies were included in the study. Bone marrow derived MSCs, umbilical cord derived MSCs (UC-MSCs), and UC-MSCs exosomes were used to modulate the burn-induced inflammation. MSCs therapy reduced serum levels of pro-inflammatory cytokines, improved renal function, inhibited tissue damage, and improved survival after burn. Furthermore, MSCs reversed all the burn-induced pathological changes in blood brain barrier (BBB).

Conclusion

MSCs may attenuate the burn-induced inflammation by decreasing serum levels of inflammatory cytokines. However, the effect on anti-inflammatory cytokines is conflicting and mandates more substantial evidence. Furthermore, MSCs reduce tissue inflammation, tissue damage, and apoptosis in the lungs and kidneys. In addition, MSCs reversed the burn-induced pathophysiologic changes in the BBB. The underlying mechanisms of these effects are poorly understood and should be the focus of future stem cell research.

Relevance to Patients

Severe burn patients are liable to systemic inflammation due to the release of inflammatory cytokines into the circulation. This inflammatory response has a broad spectrum of severity that ranges from alterations in vital signs to multiorgan failure and death. Despite the advances in burn care, burn-induced inflammation still imposes significant morbidity and mortality. This systematic review evaluates the potential benefits of stem cells in modulating burn-induced systemic inflammation in animal burn models.

Blood-Brain Barrier Dysfunction After Smoke Inhalation Injury, With and Without Skin Burn

Only a handful of published reports exist today that describe neurological complications following smoke inhalation injury. In this study, we characterize acute pathophysiological changes in the brain of sheep exposed to smoke inhalation, with- and without third-degree skin burn that models the injuries sustained by human victims of fire accidents. Blood-brain barrier integrity and hemorrhage were analyzed throughout the brain using specific histological stains: Hematoxylin & Eosin, Luxol fast blue, Periodic acid-Schiff (PAS), and Martius, Scarlet and Blue (MSB). Our data show that, following smoke inhalation injury, alone and in combination with third-degree skin burn, there was a significant increase in the number of congested and dilated blood vessels in the frontal cortex, basal ganglia, amygdala, hippocampus, pons, cerebellum, and pituitary gland as compared to sham-injured controls. Positive PAS staining confirmed damage to the basement membrane of congested and dilated blood vessels throughout the brain. Severe rupturing of blood vessels, microvascular hemorrhaging and bleeding throughout the brain was also observed in the injured groups. No significant changes in hemodynamics and PaO2 were observed. Our data demonstrate for the first time that acute smoke inhalation alone results in diffuse blood-brain barrier dysfunction and massive bleeding in the brain in the absence of hypoxia and changes in hemodynamics. These findings provide critical information and prompt further mechanistic and interventional studies necessary to develop effective and novel treatments aimed at alleviating CNS dysfunction in patients with smoke and burn injuries.

Ambient air pollution and daily hospital admissions for mental disorders in Shanghai, China

Few studies have investigated the associations between ambient air pollution and mental disorders (MDs), especially in developing countries. We conducted a time-series study to explore the associations between six criteria air pollutants and daily hospital admissions for MDs in Shanghai, China, from 2013 to 2015. The MDs data were derived from the Shanghai Health Insurance System. We used over-dispersed, generalized additive models to estimate the associations after controlling for time trend, weather conditions, day of the week, and holidays. In addition, we evaluated the effect of modification by age, sex, and season. A total of 39,143 cases of hospital admissions for MDs were identified during the study period. A 10-μg/m³ increase in 2-day, moving-average concentration of inhalable particulate matter, sulfur dioxide (SO₂), and carbon monoxide was significantly associated with increments of 1.27% [95% confidence interval (CI): 0.28%, 2.26%], 6.88% (95% CI, 2.75%, 11.00%), and 0.16% (95% CI: 0.02%, 0.30%) in daily hospital admissions for MDs, respectively. We observed positive but insignificant associations of fine particulate matter, nitrogen dioxide and ozone. The estimated association of SO₂ was relatively robust to the adjustment of simultaneous exposure to other pollutants. We found generally stronger associations of air pollutants with MDs in warm seasons than in cool seasons. There were no significant differences in the associations between different sex and age groups. This study suggested that short-term exposure to air pollution, especially to sulfur dioxide, was associated with increased risk of hospital admissions for MDs in Shanghai, China.

Limiting progressive hippocampal metabolic abnormalities after smoke inhalation injury

A 46-year-old man had a smoke inhalation injury. Within 1 month, he developed neuropsychiatric problems including toxic encephalopathy, cognitive disorder, depression symptoms and personality change. From 3 to 14 years after the toxic inhalation injury, the patient received treatment with sertraline and methylphenidate. The (18)F-fluorodeoxyglucose positron emission tomography scan at 3 years after injury showed deterioration of glucose metabolism in the hippocampus and orbital frontal region; at 14 years after injury, the hippocampus had no significant change but the orbital frontal region had deterioration of glucose metabolism. It was hypothesised that sertraline may have provided selective hippocampal neuroprotection. Further study is justified to evaluate sertraline as a possible neuroprotective agent after smoke inhalation injury.