Cholesterol metabolism: physiological versus pathological aspects in intracerebral hemorrhage.

Cholesterol is an important component of plasma membranes and participates in many basic life functions, such as the maintenance of cell membrane stability, the synthesis of steroid hormones, and myelination. Cholesterol plays a key role in the establishment and maintenance of the central nervous system. The brain contains 20% of the whole body's cholesterol, 80% of which is located within myelin. A huge number of processes (e.g., the sterol regulatory element-binding protein pathway and liver X receptor pathway) participate in the regulation of cholesterol metabolism in the brain via mechanisms that include cholesterol biosynthesis, intracellular transport, and efflux. Certain brain injuries or diseases involving crosstalk among the processes above can affect normal cholesterol metabolism to induce detrimental consequences. Therefore, we hypothesized that cholesterol-related molecules and pathways can serve as therapeutic targets for central nervous system diseases. Intracerebral hemorrhage is the most severe hemorrhagic stroke subtype, with high mortality and morbidity. Historical cholesterol levels are associated with the risk of intracerebral hemorrhage. Moreover, secondary pathological changes after intracerebral hemorrhage are associated with cholesterol metabolism dysregulation, such as neuroinflammation, demyelination, and multiple types of programmed cell death. Intracellular cholesterol accumulation in the brain has been found after intracerebral hemorrhage. In this paper, we review normal cholesterol metabolism in the central nervous system, the mechanisms known to participate in the disturbance of cholesterol metabolism after intracerebral hemorrhage, and the links between cholesterol metabolism and cell death. We also review several possible and constructive therapeutic targets identified based on cholesterol metabolism to provide cholesterol-based perspectives and a reference for those interested in the treatment of intracerebral hemorrhage.

Acute 1,2-Dichloropropane Poisoning due to Ingestion of Rubber Cement: An Autopsy Case Report and Review.

ABSTRACT: 1,2-Dichloropropane (1,2-DCP) is a common industrial solvent and chemical intermediate that can cause acute poisoning to humans through exposure during its production and industrial use. The target organs of 1,2-DCP include the eyes, respiratory system, liver, kidney, central nervous system, and skin. Forensic identification of 1,2-DCP poisoning is difficult because of the lack of characteristic pathological changes. This article reports an autopsy case of acute 1,2-DCP poisoning caused by self-ingestion of rubber cement. A woman developed seizures and coagulation dysfunction after ingesting approximately 10 mL of rubber cement and died 43 hours later. Autopsy revealed generalized subcutaneous hemorrhage, cardiopulmonary multifocal hemorrhage, bronchopneumonia, severe cerebral edema, focal hepatic necrosis, granular deposition in the glomerular capsule and renal tubules, and delipidation of the adrenal cortex. These findings indicate that 1,2-DCP poisoning can induce central nervous system dysfunction, respiratory system damage, liver and kidney function damage, hemolytic anemia, disseminated intravascular coagulation, and adrenal damage. This case may provide useful perspectives for forensic identification of 1,2-DCP poisoning in the future.

Brain-specific loss of Abcg1 disturbs cholesterol metabolism and aggravates pyroptosis and neurological deficits after traumatic brain injury.

Based on accumulating evidence, cholesterol metabolism dysfunction has been suggested to contribute to the pathophysiological process of traumatic brain injury (TBI) and lead to neurological deficits. As a key transporter of cholesterol that efflux from cells, the ATP-binding cassette (ABC) transporter family exerts many beneficial effects on central nervous system (CNS) diseases. However, there is no study regarding the effects and mechanisms of ABCG1 on TBI. As expected, TBI resulted in the different time-course changes of cholesterol metabolism-related molecules in the injured cortex. Considering ABCG1 is expressed in neuron and glia post-TBI, we generated nestin-specific Abcg1 knockout (Abcg1-KO) mice using the Cre/loxP recombination system. These Abcg1-KO mice showed reduced plasma high-density lipoprotein cholesterol levels and increased plasma lower-density lipoprotein cholesterol levels under the base condition. After TBI, these Abcg1-KO mice were susceptible to cholesterol metabolism turbulence. Moreover, Abcg1-KO exacerbated TBI-induced pyroptosis, apoptosis, neuronal cell insult, brain edema, neurological deficits, and brain lesion volume. Importantly, we found that treating with retinoid X receptor (RXR, the upstream molecule of ABCG1) agonist, bexarotene, in Abcg1-KO mice partly rescued TBI-induced neuronal damages mentioned above and improved functional deficits versus vehicle-treated group. These data show that, in addition to regulating brain cholesterol metabolism, Abcg1 improves neurological deficits through inhibiting pyroptosis, apoptosis, neuronal cell insult, and brain edema. Moreover, our findings demonstrate that the cerebroprotection of Abcg1 on TBI partly relies on the activation of the RXRalpha/PPARgamma pathway, which provides a potential therapeutic target for treating TBI.

The Neurobiological Links between Stress and Traumatic Brain Injury: A Review of Research to Date.

Neurological dysfunctions commonly occur after mild or moderate traumatic brain injury (TBI). Although most TBI patients recover from such a dysfunction in a short period of time, some present with persistent neurological deficits. Stress is a potential factor that is involved in recovery from neurological dysfunction after TBI. However, there has been limited research on the effects and mechanisms of stress on neurological dysfunctions due to TBI. In this review, we first investigate the effects of TBI and stress on neurological dysfunctions and different brain regions, such as the prefrontal cortex, hippocampus, amygdala, and hypothalamus. We then explore the neurobiological links and mechanisms between stress and TBI. Finally, we summarize the findings related to stress biomarkers and probe the possible diagnostic and therapeutic significance of stress combined with mild or moderate TBI.

Mechanism of Ferroptosis and Its Relationships with Other Types of Programmed Cell Death: Insights for Potential Therapeutic Benefits in Traumatic Brain Injury.

Traumatic brain injury (TBI) is a serious health issue with a high incidence, high morbidity, and high mortality that poses a large burden on society. Further understanding of the pathophysiology and cell death models induced by TBI may support targeted therapies for TBI patients. Ferroptosis, a model of programmed cell death first defined in 2012, is characterized by iron dyshomeostasis, lipid peroxidation, and glutathione (GSH) depletion. Ferroptosis is distinct from apoptosis, autophagy, pyroptosis, and necroptosis and has been shown to play a role in secondary brain injury and worsen long-term outcomes after TBI. This review systematically describes (1) the regulatory pathways of ferroptosis after TBI, (2) the neurobiological links between ferroptosis and other cell death models, and (3) potential therapies targeting ferroptosis for TBI patients.

Neurobiological Links between Stress, Brain Injury, and Disease.

Stress, which refers to a combination of physiological, neuroendocrine, behavioral, and emotional responses to novel or threatening stimuli, is essentially a defensive adaptation under physiological conditions. However, strong and long-lasting stress can lead to psychological and pathological damage. Growing evidence suggests that patients suffering from mild and moderate brain injuries and diseases often show severe neurological dysfunction and experience severe and persistent stressful events or environmental stimuli, whether in the acute, subacute, or recovery stage. Previous studies have shown that stress has a remarkable influence on key brain regions and brain diseases. The mechanisms through which stress affects the brain are diverse, including activation of endoplasmic reticulum stress (ERS), apoptosis, oxidative stress, and excitatory/inhibitory neuron imbalance, and may lead to behavioral and cognitive deficits. The impact of stress on brain diseases is complex and involves impediment of recovery, aggravation of cognitive impairment, and neurodegeneration. This review summarizes various stress models and their applications and then discusses the effects and mechanisms of stress on key brain regions-including the hippocampus, hypothalamus, amygdala, and prefrontal cortex-and in brain injuries and diseases-including Alzheimer's disease, stroke, traumatic brain injury, and epilepsy. Lastly, this review highlights psychological interventions and potential therapeutic targets for patients with brain injuries and diseases who experience severe and persistent stressful events.

A case of death of purulent meningitis caused by transorbital intracranial penetrating injury due to long-term residual bamboo chopstick.

This article reports a case of death caused by purulent meningitis after a long-term transorbital intracranial penetrating injury induced by a bamboo chopstick. A 53-year-old man was pierced with a bamboo chopstick into the left orbit, and the bamboo chopstick broke off. The man remained conscious after the injury but developed paroxysmal headaches. Multiple computed tomography, computed tomography angiography, and rhinoscopy detections revealed that a puncture tract had formed from the left orbit to the right edge of the brainstem through the skull base. However, there was no apparent brain injury or cerebrovascular rupture, thus excluding the possibility of a retained intracranial foreign body by the neurosurgeon. Therefore, the man only received symptomatic and conservative treatments. Unfortunately, the man was found dead one morning, 13 months later. Autopsy and histopathological examinations revealed that he died of purulent meningitis caused by a long-term residual intracranial bamboo chopstick. A review of the relevant literature regarding the diagnosis, including diagnostic values and limitations of different imaging technologies, and treatment of residual intracranial foreign bodies, revealed that this was a case of misdiagnosis, leading to delayed treatment. This case had an indirect causal relationship between the victim's death and medical treatment. This article provides clinical strategies for diagnosing and treating such cases and a forensic perspective for identifying causes of deaths attributed to medical malpractices.

Restraint Stress Delays the Recovery of Neurological Impairments and Exacerbates Brain Damages through Activating Endoplasmic Reticulum Stress-mediated Neurodegeneration/Autophagy/Apopotosis post Moderate Traumatic Brain Injury.

Based on accumulating evidence, patients recovering from mild and moderate traumatic brain injury (TBI) often experience increased sensitivity to stressful events. However, few studies have assessed on the effects and pathophysiological mechanisms of stress on TBI. In the current study, using a mouse model of moderate TBI, we investigated whether restraint stress (RS) regulates secondary neurodegeneration and neuronal cell death, which are commonly associated with neurological dysfunctions. Our data showed that RS significantly reduced body weight recovery, delayed the recovery of neurological functions (motor function, cognitive function and anxiety-like behavior) and exacerbated the brain lesion volume after moderate TBI. Immunofluorescence results indicated that moderate TBI-induced cell insults and blood-brain barrier leakage were aggravated by RS. Further Western blotting experiments showed that RS activated endoplasmic reticulum (ER) stress excessively after moderate TBI and decreased the number of NeuN-positive cells, but increased the number of CHOP/NeuN-co-positive cells by performing immunostaining in the injured cortex after moderate TBI. Moreover, RS increased the ratios of CHOP/Aß and CHOP/p-Tau co-positive cells in the injured cortex after moderate TBI. However, blocking ER stress with the classic ER stress inhibitor salubrinal remarkably decreased apoptosis and the levels of autophagy-related proteins in the mouse model of moderate TBI plus RS. Collectively, RS delays the recovery of neurological function and deteriorates morphological damage by excessively activating ER stress-mediated neurodegeneration, apoptosis and autophagy after moderate TBI. Thus, monitoring stress levels in patients recovering from non-severe TBI may merit consideration in the future.

Association between acute severe mercury poisoning and multiple organ failure.

Acute mercury poisoning, involving a number of organs, leads to severe dysfunctions, such as acute renal failure (ARF), and even threatens patients' lives. A case of acute severe mercuric chloride (HgCl2) poisoning with multiple organ failure was reported in this study. A 38-year-old woman orally took about 50 g HgCl2 powder in 2015, and showed nausea, emesis, clouding of consciousness, lip and nail cyanosis, and dark red bloody fluid from bilateral nostrils. Based on chest and abdominal CT examinations, gastroscopy, and colonoscopy, the patient was found to suffer oral mucosal hyperemia and ulceration, gastrointestinal bleeding (haematemesis and hemafecia), ARF, metabolic acidosis, collapse and shock. Despite assisted respiration and relevant active treatments, the patient's condition deteriorated gradually and she was dead eventually. The study suggests that the best treatments for acute HgCl2 poisoning accompanied with ARF are early blood purification and mercury elimination on the basis of conventional therapy.