Mild hypothermia attenuates post-resuscitation brain injury through a V-ATPase mechanism in a rat model of cardiac arrest.

Although therapeutic hypothermia is an effective treatment for post-resuscitation brain injury after cardiac arrest (CA), the underlying mechanism remains unclear. Vacuolar H(+)-ATPase (V-ATPase) plays a key role in cellular adaption to a hypoxic environment. This study sought to evaluate the effect of mild hypothermia on V-ATPase and its involvement in neuroprotection after CA. Male Sprague-Dawley rats were subjected to a 6-min CA, resuscitated successfully, and then assigned to either the normothermia (NT) group or the hypothermia (HT) group. Rats were further divided into 2 subgroups based on the time of euthanasia, either 3 or 24 h after CA (NT-3 h, HT-3 h; NT-24 h, HT-24 h). Mild hypothermia was induced following CA and maintained at 33°C for 2 h. Neurologic deficit scores were used to determine the status of neurological function. Brain specimens were analyzed by TUNEL assay, western blotting, and immunohistochemistry. V-ATPase activity was estimated by subtracting total ATP hydrolysis from the bafilomycin-sensitive activity. Mild hypothermia improved the neurological outcome (HT-24 h: 34.3 ± 16.4 vs NT-24 h: 50.3 ± 17.4) and significantly decreased neurocyte apoptosis 24 h after resuscitation. Mild hypothermia significantly increased V0a1 compared to NT-3 h; V0a1 expression was associated with a decrease in the cleaved caspase 3 expression. These findings suggested that mild hypothermia inhibits CA-induced apoptosis in the hippocampus, which may be associated with reduced V-ATPase impairment. These data provide new insights into the protective effects of hypothermia in vivo.

Resistin expression in adipose tissues and its effect on glucose metabolism in rats with brain injury.

Resistin (RSTN) expression in subcutaneous adipose tissue, and its effect on glucose metabolism in rats with traumatic brain injury, was investigated using real-time PCR, western blots, and enzyme linked immunoassays. Our results show that the expression of RSTN mRNA (3.192 ± 0.046, 4.016 ± 0.010, 6.004 ± 0.020, 8.213 ± 0.013, 11.199 ± 0.174, 15.094 ± 0.030), protein levels (1.79 ± 0.05, 1.98 ± 0.07, 2.75 ± 0.08, 3.19 ± 0.08, 4.25 ± 0.11, 4.48 ± 0.07), levels of serum insulin (512.96 ± 1.21, 580.57 ± 1.52, 769.71 ± 2.22, 826.08 ± 2.03, 1262.25 ± 3.40, 1512.80 ± 3.93), and fasting blood glucose levels (10.277 ± 0.040, 12.776 ± 0.038, 13.403 ± 0.263, 14.698 ± 0.100, 16.637 ± 0.110, 19.416 ± 0.025) were significantly higher in the traumatic rat group compared to the control group (P < 0. 05). Quantitative insulin sensitivity check index (QUICKI) was significantly lower in the traumatic group (-8.570 ± 0.005, -8.912 ± 0.004, -9.241 ± 0.022, -9.404 ± 0.007, -9.952 ± 0.007, -10.288 ± 0.002) than in the control group (-7.633 ± 0.003, -7.639 ± 0.004, -7.637 ± 0.006, -7.643 ± 0.003, -7.636 ± 0.006, -7.634 ± 0.004) (P < 0.05). Single factor linear correlation analysis showed that there was a significant negative correlation between RSTN expression and QUICKI (-0.983, P < 0.05) in the traumatic group. The increase in RSTN expression in the subcutaneous adipose tissue of rats with traumatic brain injury is likely related to the indexes of glycometabolism, including serum insulin, fasting blood glucose, and QUICKI. Our results lead us to conclude that RSTN may play an important role in the process of insulin resistance in rats with traumatic brain injury.

Effect of single nucleotide polymorphisms in the ATP-binding cassette B1 gene on the clinical outcome of traumatic brain injury.

The critical role of ATP-binding cassette B1 (ABCB1) in the function of the blood-brain barrier led us to conducted this prospective study in order to investigate the clinical outcome of patients suffering from severe traumatic brain injury. A total of 182 patients with traumatic brain injury were included in our study. Genotyping of ABCB1 C3435T and G2677T/A was conducted using polymerase chain reaction-restriction fragment length polymorphism. Using multivariate-logistic regression analysis, we found that patients carrying the CT+CC genotype of ABCB1 C3435T were more likely to have a better neurological outcome when compared with the TT genotype (odds ratio = 2.71, 95% confidence interval = 1.12-6.86). However, no significant association was found between the G2677T/A polymorphism and outcome of traumatic brain injury patients. Our study provides important information regarding the prognostic value of ABCB1 C3435T, and the ABCB1 C3435T polymorphism may be used as a predictive marker for the outcome of traumatic brain injury patients.

Variation in the BDNF gene interacts with age to predict mortality in a prospective, longitudinal cohort with severe TBI.

BACKGROUND: Mortality predictions following traumatic brain injury (TBI), and our understanding of TBI pathology, may be improved by including genetic risk in addition to traditional prognostic variables. One promising target is the gene coding for brain-derived neurotrophic factor (BDNF), a ubiquitous neurotrophin important for neuronal survival and neurogenesis. OBJECTIVE: We hypothesized the addition of BDNF genetic variation would improve mortality prediction models and that BDNF Met-carriers (rs6265) and C-carriers (rs7124442) would have the highest mortality rates post-TBI. METHODS: This study examined BDNF functional single nucleotide polymorphisms rs6265 (val66met) and rs7124442 (T>C) in relation to mortality in a prospective, longitudinal cohort with severe TBI. We examined 315 individuals receiving care for a closed head injury within the University of Pittsburgh Medical Center, aged 16 to 74 years. Mortality was examined acutely (0-7 days postinjury) and postacutely (8-365 days postinjury). A gene risk score (GRS) was developed to examine both BDNF loci. Cox proportional hazards models were used to calculate hazard ratios for survivability post-TBI while controlling for covariates. RESULTS: BDNF GRS was significantly associated with acute mortality, regardless of age. Interestingly, subjects in the hypothesized no-risk allele group had the lowest survival probability. Postacutely, BDNF-GRS interacted with age such that younger participants in the no-risk group had the highest survival probability, while older participants in the hypothesized no-risk group had the lowest probability of survival. CONCLUSIONS: These data suggest complex relationships between BDNF and TBI mortality that interact with age to influence survival predictions beyond clinical variables alone. Evidence supporting dynamic, temporal balances of pro-survival/pro-apoptotic target receptors may explain injury and age-related gene associations.

ApoE and S-100 expression and its significance in the brain tissue of rats with focal contusion.

This study explored the effect of focal cerebral contusion on the expression of ApoE and S-100, and its significance in determining the time of brain injury. Based on a rat model of cerebral contusion, immunohistochemistry was used to analyze the expressions of S-100 and ApoE at different time points after injury. Thirty minutes following cerebral contusion, ApoE protein expression was significantly increased in cortex neurons (P < 0.01), and S-100 protein expression was significantly (P < 0.001) elevated 2 h after cerebral contusion. Over time, the number of ApoE and S-100 positively expressing cells gradually increased. Three days after injury, ApoE was widely distributed throughout the tissue and the number of ApoE-positive cells and staining intensity reached a peak. ApoE expression decreased after this time point. Five days after cerebral contusion, the number of S-100-positive cells reached a peak level of expression higher than that in the control group. Our data demonstrate that the expression of ApoE and S-100 correlated with the progression of focal cerebral contusion. This suggests that both proteins may serve as effective biomarkers of focal cerebral contusions.

Analysis of key genes and modules during the courses of traumatic brain injury with microarray technology.

Gene expression data acquired at different times after traumatic brain injury (TBI) were analyzed to identify differentially expressed genes (DEGs). Interaction network analysis and functional enrichment analysis were performed to extract valuable information, which may benefit diagnosis and treatment of TBI. Microarray data were downloaded from Gene Expression Omnibus and pre-treated with MATLAB. DEGs were screened out with the SAM method. Interaction networks of the DEGs were established, followed by module analysis and functional enrichment analysis to obtain insight into the molecular mechanisms. A total of 39 samples at six time points (30 min, 4, 8, 24 , 72 h, and 21 days) were analyzed and generated 377 DEGs. Eight modules were identified from the networks and network ontology analysis revealed that cell surface receptor-linked signaling pathway, response to wounding and signaling pathway were significantly overrepresented. Altered risk genes and modules in TBI were uncovered through comparing the gene expression data acquired at various time points. These genes or modules could be potential biomarkers for diagnosis and treatment of TBI.

IL-6 polymorphism associated with fatal outcome in patients with severe traumatic brain injury.

OBJECTIVE: The aim of this study was to test whether a functional polymorphism (-174C/G) located in the promoter region of the interleukin-6 (IL-6) gene is associated with primary short-term outcome (death or Intensive Care Unit discharge) in patients with severe traumatic brain injury (TBI). METHODS: The study group consisted of 77 male patients who suffered severe TBI. The -174C/G IL-6 polymorphism was analysed by polymerase chain reaction (PCR) followed by restriction digestion. RESULTS: Severe TBI was associated with a 44% mortality rate. The GG genotype was significantly more frequent in the survivor group than in non-surviving patients (67% vs 41%; p =?0.038); similarly, the IL-6 -174G allele was more frequent in the survivor group than in non-surviving patients (81% vs 65%; p =0.031). CONCLUSION: The findings indicate that genetic variation regarding inflammatory response has significant impact on the short-term outcome for patients after acute severe TBI.

Upregulation of EphA3 receptor after spinal cord injury.

Spinal cord injury (SCI) releases a cascade of events that leads to the onset of an inhibitory milieu for axonal regeneration. Some of these changes result from the presence of repulsive factors that may restrict axonal outgrowth after trauma. The Eph receptor tyrosine kinase (RTK) family has emerged as a key repellent cue known to be involved in neurite outgrowth, synapse formation, and axonal pathfinding during development. Given the nonpermissive environment for axonal regeneration after SCI, we questioned whether re-expression of one of these molecules occurs during regenerative failure. We examined the expression profile of EphA3 at the mRNA and protein levels after SCI, using the NYU contusion model. There is a differential distribution of this molecule in the adult spinal cord and EphA3 showed an increase in expression after several injury models like optic nerve and brain injury. Standardized semi-quantitative RT-PCR analysis demonstrated a time-dependent change in EphA3 mRNA levels, without alterations in beta-actin levels. The basal level of EphA3 mRNA in the adult spinal cord is low and its expression was induced 2 days after trauma (the earliest time point analyzed) and this upregulation persisted for 28 days post-injury (the latest time point examined). These results were corroborated at the protein level by immunohistochemical analysis and the cell phenotype identified by double labeling studies. In control animals, EphA3 immunoreactivity was observed in motor neurons of the ventral horn but not in lesioned animals. In addition, GFAP-positive cells were visualized in the ventral region of injured white matter. These results suggest that upregulation of EphA3 in reactive astrocytes may contribute to the repulsive environment for neurite outgrowth and may be involved in the pathophysiology generated after SCI.