Jiyao Jiang

Neuroprotective effects of ischemic postconditioning on global brain ischemia in rats through upregulation of hippocampal glutamine synthetase

Brain ischemic postconditioning is the induction of brief periods of ischemia-reperfusion during the early stages following ischemia, and it has been shown to produce neuroprotective effects. The mechanisms underlying these neuroprotective effects are poorly understood. Glutamate excitotoxicity is one cause of postischemic neuronal death. Glutamine synthetase (GS) is an enzyme that is expressed in glial cells and may affect glutamate excitotoxicity. We induced global ischemia in rats and performed postconditioning with 6 cycles of 10 seconds reperfusion and 10 seconds reocclusion before final reperfusion. Hematoxylin and eosin staining revealed extensive neuronal loss (44.0 ± 2.8% cell survival) in the hippocampal CA1 region. Ischemic postconditioning decreased neuronal death (82.0 ± 5.6% cell survival; p<0.05). Western blotting revealed significantly increased GS expression in the hippocampus for the ischemia-reperfusion group over time compared with the sham group (p<0.05). Ischemic postconditioning resulted in significantly increased (p<0.05) GS expression compared with both the sham and ischemia-reperfusion groups, suggesting that upregulation of GS expression after ischemia constitutes a neuroprotective mechanism.

Activations of GABAergic signaling, HSP70 and MAPK cascades are involved in baicalin's neuroprotection against gerbil global ischemia/reperfusion injury

Baicalin, a flavonoid compound isolated from the plant Scutellaria baicalensis Georgi, is known as a protective agent against delayed neuronal cell death after ischemia/reperfusion. To investigate the neuroprotective mechanism of baicalin, the present study was conducted to explore whether the alterations of GABAergic signaling, heat shock protein 70 (HSP70) and mitogen-activated protein kinases (MAPKs) were involved in its neuroprotection on gerbils global ischemia. The bilateral carotid arteries were occluded by 5 min and baicalin at the dose of 200 mg/kg was intraperitoneally injected into the gerbils immediately after cerebral ischemia. Seven days after reperfusion, neurological deficit was scored and changes in hippocampal neuronal cell death were assessed by Nissl staining as well as NeuN immunohistochemistry. The mRNA and protein expressions of GABAergic signal molecules (GABA(A)R α1, GABA(A)R γ2, KCC2 and NKCC1) were determined in ischemic hippocampus by real-time RT-PCR and Western blot, respectively. In addition, HSP70 and MAPKs cascades (ERK, JNK and p38) were also detected using western blot assay. Our results illustrated that baicalin treatment significantly facilitated neurological function, suppressed the ischemia-induced neuronal damage. Besides, administration of baicalin also caused a striking increase of GABA(A)R α1, GABA(A)R γ2 and KCC2 together with the decrease of NKCC1 at mRNA and protein levels in gerbils hippocampus following an ischemic insult. Furthermore, the protein expressions of HSP70 and phosphorylated ERK (p-ERK) were evidently augmented while the phosphorylated JNK (p-JNK) and phosphorylated p38 (p-p38) were strikingly diminished in ischemic gerbils with baicalin treatment. These findings suggest that baicalin activates GABAergic signaling, HSP70 and MAPKs cascades in global ischemia, which may be a mechanism underlying the baicalins neuroprotection.

Glial fibrillary acidic protein as a biomarker in severe traumatic brain injury patients: a prospective cohort study

IntroductionGlial fibrillary acidic protein (GFAP) may serve as a serum marker of traumatic brain injury (TBI) that can be used to monitor biochemical changes in patients and gauge the response to treatment. However, the temporal profile of serum GFAP in the acute period of brain injury and the associated utility for outcome prediction has not been elucidated.MethodsWe conducted a prospective longitudinal cohort study of consecutive severe TBI patients in a local tertiary neurotrauma center in Shanghai, China, between March 2011 and September 2014. All patients were monitored and managed with a standardized protocol with inclusion of hypothermia and other intensive care treatments. Serum specimens were collected on admission and then daily for the first 5xa0days. GFAP levels were measured using enzyme-linked immunosorbent assay techniques. Patient outcome was assessed at 6xa0months post injury with the Glasgow Outcome Scale and further grouped into death versus survival and unfavorable versus favorable.ResultsA total of 67 patients were enrolled in the study. The mean time from injury to admission was 2.6xa0hours, and the median admission Glasgow Coma Scale score was 6. Compared with healthy subjects, patients with severe TBI had increased GFAP levels on admission and over the subsequent 5xa0days post injury. Serum GFAP levels showed a gradual reduction from admission to day 3, and then rebounded on day 4 when hypothermia was discontinued with slow rewarming. GFAP levels were significantly higher in patients who died or had an unfavorable outcome across all time points than in those who were alive or had a favorable outcome. Results of receiver operating characteristic curve analysis indicated that serum GFAP at each time point could predict neurological outcome at 6xa0months. The areas under the curve for GFAP on admission were 0.761 for death and 0.823 for unfavorable outcome, which were higher than those for clinical variables such as age, Glasgow Coma Scale score, and pupil reactions.ConclusionsSerum GFAP levels on admission and during the first 5xa0days of injury were increased in patients with severe TBI and were predictive of neurological outcome at 6xa0months.

Moderate Hypothermia Significantly Decreases Hippocampal Cell Death Involving Autophagy Pathway after Moderate Traumatic Brain Injury

Here, we evaluated changes in autophagy after post-traumatic brain injury (TBI) followed by moderate hypothermia in rats. Adult male Sprague-Dawley rats were randomly divided into four groups: sham injury with normothermia group (37 °C); sham injury with hypothermia group (32 °C); TBI with normothermia group (TNG; 37 °C); and TBI with hypothermia group (THG; 32 °C). Injury was induced by a fluid percussion TBI device. Moderate hypothermia (32 °C) was achieved by partial immersion in a water bath (0 °C) under general anesthesia for 4 h. All rats were killed at 24 h after fluid percussion TBI. The ipsilateral hippocampus in all rats was analyzed with hematoxylin and eosin staining; terminal deoxynucleoitidyl transferase-mediated nick end labeling staining was used to determine cell death in ipsilateral hippocampus. Immunohistochemistry and western blotting of microtubule-associated protein light chain 3 (LC3), Beclin-1, as well as transmission electron microscopy performed to assess changes in autophagy. At 24 h after TBI, the cell death index was 27.90 ± 2.36% in TNG and 14.90 ± 1.52% in THG. Expression level of LC3 and Beclin-1 were significantly increased after TBI and were further up-regulated after post-TBI hypothermia. Further, ultrastructural observations showed that there was a marked increase of autophagosomes and autolysosomes in ipsilateral hippocampus after post-TBI hypothermia. Our data demonstrated that moderate hypothermia significantly attenuated cell death and increased autophagy in ipsilateral hippocampus after fluid percussion TBI. In conclusion, autophagy pathway may participate in the neuroprotective effect of post-TBI hypothermia.

The Up-Regulation of Voltage-Gated Sodium Channel NaV1.6 Expression Following Fluid Percussion Traumatic Brain Injury in Rats

BACKGROUNDThe influx of Na+ and the depolarization mediated by voltage-gated sodium channels (VGSCs) is an early event in traumatic brain injury (TBI) induced cellular abnormalities and is therefore well positioned as an upstream target for pharmacologic modulation of the pathological responses to TBI. Alteration in the expression of the VGSC α-subunit has occurred in a variety of neuropathological states including focal cerebral ischemia, spinal injury, and epilepsy. OBJECTIVEIn this study, changes in Nav1.6 mRNA and protein expression were investigated in rat hippocampus after TBI. METHODSForty-eight adult male Sprague Dawley rats were randomly assigned to control or TBI groups. TBI was induced with a lateral fluid percussion device. Expression of mRNA and protein for Nav1.6 in the bilateral hippocampus was examined at 2, 12, 24, and 72 hours after injury by real-time quantitative polymerase chain reaction and Western blot. Immunofluorescence was performed to localize the expression of Nav1.6 protein in the hippocampus. RESULTSExpression of >Nav1.6 mRNA was significantly up-regulated in the bilateral hippocampus at 2 and 12 hours post-TBI. Significant up-regulation of Nav1.6 protein was identified in the ipsilateral hippocampus from 2 to 72 hours post-TBI and in the contralateral hippocampus from 2 to 24 hours post-TBI. Expression of Nav1.6 occurred predominantly in neurons in the hippocampus. CONCLUSIONResults of the study showed significant up-regulation of mRNA and protein for Nav1.6 in rat hippocampal neurons after TBI.

Attenuation of Cell Death in Injured Cortex After Post-Traumatic Brain Injury Moderate Hypothermia: Possible Involvement of Autophagy Pathway

OBJECTIVEnMultiple mechanisms participated in the cell death after fluid percussion traumatic brain injury (TBI). In the present study, we evaluated the effect on cell death in the injured cortex after fluid percussion TBI and investigated a possible role of autophagy.nnnMETHODSnTBI model was induced by a fluid percussion TBI device. Moderate hypothermia (32°C) was achieved by partial immersion in a water bath (0°C) under general anesthesia for 4 hours. All rats were killed at 6 or 24 hours after TBI.nnnRESULTSnCleaved caspase 3 evaluated with Western blotting and terminal deoxynucleotidyl transferase-mediated 2-deoxyuridine 5-triphosphate-biotin nick end labeling-positive cells in injured cortex were significantly increased 6 hours after fluid percussion TBI and were further up-regulated 24 hours after TBI, dramatic up-regulation of Beclin-1 and protein light chain-3 expression levels was also observed. Further up-regulation of biomarkers of autophagy, attenuation of caspase 3 up-regulation and reduction of cell death was observed after 4 hours of hypothermia. Immunofluorescence analysis for cell localization demonstrated that protein light chain-3- and Beclin-1-positive cells included neurons and glial cells in the injured cortex after TBI and hypothermic treatment. By ultrastructural observation, autolysosomes in injured cortex were significantly increased at 6 and 24 hours after TBI and were further up-regulated after TBI hypothermic treatment.nnnCONCLUSIONSnThese data suggest that hypothermic treatment could attenuate TBI-induced cell death in this fluid percussion TBI model, possibly through activation of autophagy pathway.

Autophagy Inhibitor 3-MA Weakens Neuroprotective Effects of Posttraumatic Brain Injury Moderate Hypothermia

OBJECTIVEnThe role of autophagy in moderate hypothermia in posttraumatic brain injury (post-TBI) remains elusive. In this study, we evaluated the protective role of autophagy in post-TBI moderate hypothermia.nnnMETHODSnAdult male Sprague-Dawley rats were randomly divided into 3 groups (nxa0= 36/group): TBI with hypothermia group (sham), TBI with hypothermia and a single intracerebroventricular injection of saline (saline, 5 μL), and TBI with hypothermia and a single intracerebroventricular injection of 3-methyladenine (600 nmol, diluted in 0.9% saline to a final volume of 5 μL). All rats, except those in the behavioral tests, were killed at 24 hours after fluid percussion TBI. Immunohistochemistry staining, western blot, and transmission electron microscopy were performed to assess changes in apoptosis and autophagy after injection of 3-methyladenine. Motor function (beam-walk test) and spatial learning/memory (Morris water maze) were assessed on postoperative days 1-5 and 11-15, respectively.nnnRESULTSnOur results showed downregulation of the expression level of microtubule-associated protein 1 light chain 3 and Beclin-1, aggravation of behavioral outcome, and increase of apoptosis.nnnCONCLUSIONnOur results suggest that the autophagy pathway is involved in the neuroprotective effect of post-TBI hypothermia and negative modulation of apoptosis may be 1 possible mechanism.

Rationale, methodology, and implementation of a nationwide multicenter randomized controlled trial of long-term mild hypothermia for severe traumatic brain injury (the LTH-1 trial).

BACKGROUNDnTraumatic brain injury (TBI) is a major public health problem recently, however, no intervention showing convincing efficacy. Therapeutic hypothermia with a relatively long duration (more than 48 h), as a promising treatment measure, might improve the patient outcome following severe TBI.nnnMETHODS/DESIGNnThe LTH-1 trial is a prospective, nationwide multicenter, randomized, controlled clinical trial to examine the efficacy and safety of long-term mild hypothermia in adult patients after severe traumatic brain injury. A total of 300 consecutive patients will be recruited from 15 large neurosurgical centers in China. The eligible patient will be randomized to receive either long-term mild hypothermia (34-35 °C) for 5 days, or normothermia (36-37 °C). Additionally, a standardized management protocol will be used in all patients. The primary end point is the neurological outcome 6 months post-injury on the Glasgow Outcome Scale. The secondary outcomes include GOS score at one month post-injury, mortality during six months after injury, length of ICU and hospital stay, intracranial pressure control and Glasgow Coma Scale score during the hospital stay and frequency of complications during the six-month follow-up period.nnnDISCUSSIONnLong-term hypothermia is recommended by most recent studies and its efficacy urgently needs to be established in randomized controlled settings. The LTH-1 trial, together with other ongoing studies, will present more evidence for optimal use of hypothermia in severe TBI patients.

ID1 affects the efficacy of radiotherapy in glioblastoma through inhibition of DNA repair pathways

Glioblastoma multiforme (GBM) is characterized by poor therapeutic response and poor overall survival. It is crucial that more effective therapies be developed for the treatment of GBM. Inhibitor of DNA binding protein-1 (ID1) has been shown to maintain the self-renewal capacity of neural stem cells and might be involved in the therapeutic resistance of GBM. In the present study, we explored survival data from the The Cancer Genome Atalas database that were based on ID1 expression for patients diagnosed with primary GBMs. Interestingly, patients with high ID1 expression had better survival than patients with low ID1 expression, and a strong correlation was found between radiotherapy efficacy, ID1 expression, and overall survival. We further investigated the relationship between ID1 expression and the radiosensitivity of glioblastoma using glioblastoma cell lines. The clonogenic formation assay showed that U87 ID1-shRNA cells were much less sensitive to radiation. Moreover, both the results of the γH2AX foci staining assay and the comet assay further revealed that ID1 negatively regulates DNA repair processes by downregulating the expression of genes such as DNA ligase IV (LIG4) and ataxia-telangiectasia-mutated. Additionally, ID1 induces G2/M arrest in U87 cells. Taken together, these results suggest that ID1 may be a new prognostic marker for GBM and have important implications for the therapeutic strategies used to treat GBM patients.

Acute Traumatic Brain Injury: Is Current Management Evidence Based? An Empirical Analysis of Systematic Reviews

Traumatic brain injury (TBI) is a major health and socioeconomic problem worldwide with a high rate of death and long-term disability. Previous studies have summarized evidence from large-scale randomized trials, finding no intervention showing convincing efficacy for acute TBI management. The present empirical study set out to assess another crucial component of evidence base-systematic review, which contributes a lot to evidence-based health care, in terms of clinical issues, methodological aspects, and implication for practice and research. A total of 44 systematic reviews pertaining to therapeutic interventions for acute TBI were identified through electronic database searching, clinical guideline retrieval, and expert consultation, of which 21 were published in Cochrane Library and 23 in peer-reviewed journals. Their methodological quality was generally satisfactory, with the median Overview Quality Assessment Questionnaire score of 5.5 (interquartile range 2-7). Cochrane reviews are of better quality than regular journal reviews. Twenty-nine high-quality reviews provided no conclusive evidence for the investigated 22 interventions except for an adverse effect of corticosteroids. Less than one-third of the component trials were reported with adequate allocation concealment. Additionally other methodological flaws in design-for example, ignoring heterogeneity among the TBI population-also contributed to the failure of past clinical research. Based on the above findings, evidence from both systematic reviews and clinical trials does not fully support current management of acute TBI. Translating from laboratory success to clinical effect remains an unique challenge. Accordingly it may be the time to rethink the way in future practice and clinical research in TBI.