Improvement of Mechanical Stability for Single Unit Recording Based on Skull Cap in Living Chinchilla.

Three-point head fixation was constructed to provide mechanical stability for single unit recording (SUR) on vestibular sensory system in living chinchilla previously. However, it is no more qualified to this work when the stimulation intensity becomes large because of frequent unit losing and neuron damage, which strongly implies that the mechanical stability has been broken during the stimulation. Here, we constructed a novel head fixation (skull cap assistant head fixation) provided by skull cap on the basis of three-point head fixation in order to improve the mechanical stability for SUR under the stimulation with large magnitude. The large area bone connection is the feature and advantage of this improved method, which directly fixes the tested local nervous tissue and microelectrode in an intact stable system through skull cap except two ear bars and a tube face mask. Our data exhibited that skull cap assistant head fixation could significantly improve the success rate of neural response activity recording in the population of semicircular canal neurons under the stimulation with large intensity (amplitude ≥100 deg/s). Based on the analysis of neural response activity and noise base-line during stimulation, our data further indicated that this method could significantly improve the mechanical stability for SUR during high-speed motion stimulation on vestibular system in living chinchilla. Skull cap assistant head fixation extends the application of SUR on vestibular neuron in linear response range and provides a solid foundation for electrophysiological research on vestibular sensory system in further studies.

Allicin protects spinal cord neurons from glutamate-induced oxidative stress through regulating the heat shock protein 70/inducible nitric oxide synthase pathway.

Allicin, the main biologically active compound derived from garlic, exerts a broad spectrum of pharmacological activities and is considered to have therapeutic potential in many neurological disorders. Using an in vitro spinal cord injury model induced by glutamate treatment, we sought to investigate the neuroprotective effects of allicin in primary cultured spinal cord neurons. We found that allicin treatment significantly attenuated glutamate-induced lactate dehydrogenase (LDH) release, loss of cell viability and apoptotic neuronal death. This protection was associated with reduced oxidative stress, as evidenced by decreased reactive oxygen species (ROS) generation, reduced lipid peroxidation and preservation of antioxidant enzyme activities. The results of western blot analysis showed that allicin decreased the expression of inducible nitric oxide synthase (iNOS), but had no effects on the expression of neuronal NOS (nNOS) following glutamate exposure. Moreover, allicin treatment significantly increased the expression of heat shock protein 70 (HSP70) at both mRNA and protein levels. Knockdown of HSP70 by specific targeted small interfere RNA (siRNA) not only mitigated allicin-induced protective activity, but also partially nullified its effects on the regulation of iNOS. Collectively, these data demonstrate that allicin treatment may be an effective therapeutic strategy for spinal cord injury, and that the potential underlying mechanism involves HSP70/iNOS pathway-mediated inhibition of oxidative stress.

The mGluR5 positive allosteric modulator CDPPB inhibits SO2-induced protein radical formation and mitochondrial dysfunction through activation of Akt in mouse hippocampal HT22 cells.

Sulfur dioxide (SO2) is a common gas pollutant that is detrimental to many organs. Previous studies have shown that SO2 exposure is involved in neurotoxicity and increased risk of many brain disorders; however, our understanding of the mechanisms underlying SO2-induced cytotoxicity on neuronal cells remains elusive. The group I metabotropic glutamate receptor 5 (mGluR5) can modulate addiction, pain, and neuronal cell death. In the present study, we showed that SO2 derivatives exposure induced protein radical formation, mitochondrial dysfunction, and apoptotic cell death in neuronal HT22 cells. Pretreatment with 3-cyano-N-(1,3-diphenyl-1H-pyrazol-5-yl) (CDPPB), a positive allosteric modulator of mGluR5, significantly attenuated SO2-induced neurotoxicity, which was fully prevented by the mGluR5 antagonist MPEP. CDPPB reduced the protein radical formation and inducible nitric oxide synthase (iNOS)-derived generation of nitric oxide, and inhibited mitochondrial dysfunction in both HT22 cells and isolated mitochondria after SO2 treatment. Moreover, CDPPB increased the activation of Akt in the presence and absence of SO2 treatment. Blocking Akt activation using the selective inhibitor LY294002 partially reversed the CDPPB-induced protection against SO2-induced neurotoxicity. This study provides mechanistic experimental support for oxidative stress and mitochondrial dysfunction after SO2 exposure in neuronal cells, and also introduces a novel therapeutic approach for SO2-induced neurotoxicity.

Small-molecule inhibitors at the PSD-95/nNOS interface attenuate MPP+-induced neuronal injury through Sirt3 mediated inhibition of mitochondrial dysfunction.

Post-synaptic density protein 95 (PSD-95) links neuronal nitric oxide synthase (nNOS) with the N-methyl-D-aspartic acid (NMDA) receptor in the central nervous system, and this molecular complex has been implicated in regulating neuronal excitability in several neurological disorders. Here, small-molecule inhibitors of the PSD-95/nNOS interaction, IC87201 and ZL006 were tested for neuroprotective effects in an in vitro Parkinson's disease (PD) model. We now report that IC87201 and ZL006 reduced MPP(+)-induced neuronal injury and apoptotic cell death in a dose-dependent manner in cultured cortical neurons. These protective effects were associated with suppressed mitochondrial dysfunction, as evidenced by decreased reactive oxygen species (ROS) generation, cytochrome c release, mitochondrial membrane potential (MMP) collapse, and the preserved mitochondrial complex I activity and ATP synthesis. IC87201 and ZL006 also preserved intracellular homeostasis through mitigating mitochondrial Ca(2+) uptake and promoting mitochondrial Ca(2+) buffering capacity. Moreover, treatment with IC87201 and ZL006 significantly increased the expression of Sirt3 after MPP(+) exposure, and knockdown of Sirt3 using specific targeted small interfere RNA (siRNA) partially nullified the protective effects induced by these two inhibitors. These data strongly support the hypothesis that targeting the PSD-95/nNOS interaction produces neuroprotective effects and may represent a novel class of therapeutics for PD as well as other neurological diseases where detrimental NMDA receptor signaling plays a major role.

[Treatment of unstable lumbar intervertebral disc herniation by modified lamina osteotomy replantation].

OBJECTIVE: To evaluate the clinical effects of the modified lamina replantation for the treatment of unstable lumbar intervertebral disc herniation. METHODS: From March 2009 to August 2011,63 patients with unstable lumbar intervertebral disc herniation were treated by discectomy, interbody fusion, pedicle screw fixation, and modified lamina replantation. There were 33 males and 30 females with an average age of 48.4 years old ranging from 22 to 68 years old. The average duration of disease was 38.8 months ranging from 3 months to 13 years. All patients had lower back and leg pains. X-ray,CT and MR results showed unstable lumbar intervertebral disc herniation. Preoperative and postoperative ODI, JOA scores, complication incident rates,radiographic healing rates,and lower back and leg pain recurrence rates were observed and recorded. RESULTS: Sixty-two incisions were healed at first stage, 1 at second stage. There were no complications such as deep vein thrombosis, intervertebral infection and so on. Sixty-one patients were followed up for more than one year, and the mean duration was 33 months. Nerve and dural injury occurred in 2 patients and 1 patient respectively. One-year fusion happened in 58 patients while the recurrence of lower back pain and leg pain after 1 year were noted in 4 patients and 1 patient respectively. ODI, and JOA scores were respectively re-assessed at 2 weeks, 6 months and 1 year after the operation, and the results showed a significant difference from the preoperative scores (P < 0.05). CONCLUSION: Modified lamina replantation for unstable lumbar intervertebral disc herniation showed lower rates of dural and nerve damage, as well as a higher lamina healing rate, lower back and leg pain recovery rate, and a better clinical score. It is a safe and efficient operation choice for lumbar spine surgery.

Some insights into the binding mechanism of Aurora B kinase gained by molecular dynamics simulation.

Aurora B kinase is essential in the process of mitosis, and its overexpression has been reported to be associated with a number of solid tumors. We therefore carried out molecular docking, molecular dynamics, and molecular mechanics Poisson-Boltzmann/surface area (MM-PBSA) calculations on several structurally diverse inhibitors (pentacyclic, pyrimidine, quinazoline, and pyrrolopyridine derivatives) and Aurora B kinase to explore the structural and chemical features responsible for the binding recognition mechanism. Molecular simulations reveal that the binding site mainly consists of six binding regions (sites A-F). We have identified that sites B and C are required for optimum binding in Aurora B-inhibitor complexes, sites A and F are needed to improve pharmacokinetic properties, while sites D and E lead to enhanced stability. We verified that hydrogen bonding to the hinge region and hydrophobic contact with the conserved hydrophobic pocket are of critical importance in the systems studied. Specifically, the amino acids Glu171, Phe172, and Ala173 in the hinge region and Leu99, Val107, and Leu223 in the conserved hydrophobic pocket probably account for the high binding affinities of these systems, as shown by hydrogen-bonding analysis and energy decomposition analysis. Hydrophobic contact with Phe172 is also in agreement with experimental data. In addition, the MM-PBSA calculations reveal that the binding of these inhibitors to Aurora B kinase is mainly driven by van der Waals/nonpolar interactions. The findings of this study should help to elucidate the binding pattern of Aurora B inhibitors and aid in the design of novel active ligands.

[Drug delivery of CPC/amifostine/cisplatin complex in vitro and its ability in repairing bone defect and eliminating tumor in vivo].

OBJECTIVE: To investigate the feasibility of using calcium phosphate cement/amifostine/cisplatin complex to fill and repair bone defect, caused by tumor resection. METHODS: Drug concentration in the CPC/ amifostine/cisplatin complex was determined. Rabbits with bone defect and rats with osteosarcoma were implanted with CPC and CPC/amifostine/cisplatin complex. RESULTS: Similar bone growth was observed in the femurs of rabbits implanted with CPC/amifostine/cisplatin complex and those implanted with CPC. CPC/amifostine/cisplatin complex delivered amifostine and cisplatin consistently and eliminated osteosarcoma cells implanted in the rats. CONCLUSION: CPC/amifostine/cisplatin complex repairs bone defect caused by tumors as a filling material.

[Physicochemical and sustained drug release properties of calcium phosphate cement/amifostine/cisplatin complex and its effect in repairing bone defect due to tumor resection in rabbits].

OBJECTIVE: To investigate the feasibility of using calcium phosphate cement/amifostine complex as an new filling material for repairing bone defect caused by tumor resection. METHODS: Calcium phosphate cement (CPC)/cisplatin/amifostine complex was prepared at the mass ratio of 1000:2:5. The setting time, mechanical strength, and porosity of the complex were determined, and scanning electron microscopy and assessment of sustained drug release and inhibitory effect against osteosarcoma cells were carried out. The degradation of the material and new bone ingrowth were also observed in a rabbit model of femoral bone defect. RESULTS: The setting time, strength, and porosity, appearances under scanning electron microscope, and sustained drug release properties of CPC/cisplatin/amifostine complex were identical to those of CPC, and the integration of amifostine in the complex did not affect the cytotoxicity of cisplatin against the osteosarcoma cells. Pathological evidences of the degradation of the material and new bone ingrowth into the material were observed with the passage of time following its implantation into the bone defect in rabbits. CONCLUSION: The CPC/cisplatin/amifostine complex can be used as a filling material for repairing bone defect caused by tumor resection and eliminating the residual tumor cells in rabbits.