Optimized terahertz generation in BNA organic crystals with chirped Ti:sapphire laser pulses.

We report on the efficient generation of intense terahertz radiation from the organic crystal N-benzyl-2-methyl-4-nitroaniline pumped by chirped Ti:sapphire femtosecond laser pulses. The THz energy and spectrum as a function of the pump fluence and duration of the chirped laser pulses are studied systematically. For the appropriate positively chirped pump pulses, a significant boost in the THz generation efficiency by a factor of around 2.5 is achieved, and the enhancement of high-frequency components (>1 THz) shortens the THz pulse duration. Via complete characterization of THz properties and transmitted laser spectra, this nonlinear behavior is attributed to the extended effective interaction length for phase matching as a result of the self-phase modulation of the intense pump laser pulses. Numerical calculations well reproduce the experimental observation. Our results demonstrate a robust, efficient, strong-field (up to several MV/cm) THz source using the common sub-10 mJ and sub-100 fs Ti:sapphire laser systems without optical parametric amplifiers.

The Role of Klotho Protein Against Sevoflurane-Induced Neuronal Injury.

The effects of general anesthetics on the developing brain have aroused much attention in recent years. Sevoflurane, a commonly used inhalation anesthetic especially in pediatric anesthesia, can induce developmental neurotoxicity. In this study, the differentially expressed mRNAs in the hippocampus of newborn rats exposed to 3% sevoflurane for 6 h were detected by RNA-Sequencing. Those data indicated that the mRNA of Klotho was increased after exposure to sevoflurane. Moreover, the protein expression of Klotho was assayed by Western Blot. Besides over-expression and under-expression of Klotho protein, we also detected changes of cell proliferation, ROS, JC-1, and Bcl-2/Bax ratio in PC12 cells exposed to sevoflurane. After exposure to 3% sevoflurane, the expression of Klotho protein increased in the hippocampus of neonatal rats. In PC12 cells, exposure to sevoflurane could increase cellular ROS level, reduce mitochondrial membrane potential and Bcl-2/Bax ratio. While overexpression of Klotho alleviated the above changes, knockdown of Klotho aggravated the injury of sevoflurane. Klotho protein could reduce oxidative stress and mitochondrial injury induced by sevoflurane in the neuron.

Advanced glycation end products activate the miRNA/RhoA/ROCK2 pathway in endothelial cells.

OBJECTIVE: AGEs induce endothelial cell dysfunction in HUVECs, resulting in ROS production and triggering apoptosis. This study sought to identify miRNAs involved in AGE-induced endothelial cell injury. METHODS: Microarray analysis to identify miRNAs altered with AGE stimulation was undertaken, and results were confirmed using real-time quantitative polymerase chain reaction. The interaction of miRNAs with the RhoA and ROCK2 genes was confirmed using luciferase assays, and their effects on expression were determined using Western blot analysis. The effects of AGEs and miRNAs on endothelial cell permeability were assessed. RESULTS: AGEs induced ROS production and apoptosis of HUVECs (p < 0.05). AGE-induced miR-200b and miR-200c downregulation led to increased expression of their target genes, RhoA and ROCK, respectively. AGE-induced endothelial cell permeability and F-actin expression were significantly reduced with both miR-200b and miR-200c mimics (p < 0.05). Furthermore, AGE-induced stress fiber formation was reduced in cells treated with miR-200b mimics. CONCLUSION: miR-200b and miR-200c are suppressed in AGE-induced endothelial cell injury, resulting in unregulated RhoA/ROCK2 signaling. Further studies are necessary to evaluate the therapeutic value of targeting miRNAs or their target genes for treatment of vascular diseases.

Intrathecal rapamycin attenuates the mechanical hyperalgesia of paclitaxel-induced peripheral neuropathy in mice.

Paclitaxel is an extensively used chemotherapy antitumor drug and paclitaxel-induced peripheral neuropathy (PIPN) is one of the most common side effect. Rapamycin, originally used as an adjuvant drug for chemotherapy, has recently been found to possess potential neuroprotective activities. Our purposes of this study are to verify the effect of rapamycin on PIPN, which contributes to a new target for PIPN treatment. Mice were given paclitaxel or rapamycin with different injection methods. Paw withdrawal threshold was tested at different time points for mechanical sensitivity assessment. Administration of paclitaxel, both 2 mg/kg and 5 mg/kg, could induce mechanical hypersensitivity. 0.01 mg intrathecal injection of rapamycin showed the best effect on attenuate the mechanical hyperalgesia of PIPN. Intrathecal injection of only rapamycin would not induce the mechanical hyperalgesia while when rapamycin and paclitaxel were used together the mechanical hyperalgesia induced by paclitaxel could be attenuated. Paclitaxel could induce mechanical hyperalgesia in mice and rapamycin could attenuate such mechanical hyperalgesia of PIPN.

A non-collinear autocorrelator for single-shot characterization of ultrabroadband terahertz pulses.

Conventional terahertz (THz) waveform or spectral diagnostics mainly employ the electro-optic-based techniques or the multi-shot Michelson interferometer. Simultaneously, single-shot, ultrabroadband THz spectral measurements remain challenging. In this paper, a novel probe-free scheme based on the non-collinear autocorrelation technique is proposed to characterize the ultrabroadband THz spectrum at a single-shot mode. The non-collinear autocorrelator is a modified beam-division interferometer, in which the two beams are recombined non-collinearly onto a camera. The temporal or spectral resolution and range depend on the noncollinear configuration and camera parameters. This simple approach has been applied experimentally to characterize the ultrashort THz pulse generated from ultraintense laser-solid interactions, demonstrating the capability of single-shot ultrabroadband measurements without an auxiliary ultrafast laser probe. The proposed non-collinear autocorrelator here would be much useful for characterization and applications of low-repetition-rate intense THz sources and could also be extended to other frequency bands.

Highly efficient generation of GV/m-level terahertz pulses from intense femtosecond laser-foil interactions.

The terahertz radiation from ultraintense laser-produced plasmas has aroused increasing attention recently as a promising approach toward strong terahertz sources. Here, we present the highly efficient production of millijoule-level terahertz pulses, from the rear side of a metal foil irradiated by a 10-TW femtosecond laser pulse. By characterizing the terahertz and electron emission in combination with particle-in-cell simulations, the physical reasons behind the efficient terahertz generation are discussed. The resulting focused terahertz electric field strength reaches over 2 GV/m, which is justified by experiments on terahertz strong-field-driven nonlinearity in semiconductors.

Two-dimensional monitoring of a laser-solid x-ray source spot via penumbral coded aperture imaging technique.

The uncertainties of spot size and position need to be clarified for x-ray sources as they can affect the detecting precision of the x-ray probe beam in applications such as radiography. In particular, for laser-driven x-ray sources, they would be more significant as they influence the inevitable fluctuation of the driving laser pulses. Here, we have employed the penumberal coded aperture imaging technique to diagnose the two-dimensional spatial distribution of an x-ray emission source spot generated from a Cu solid target irradiated by an intense laser pulse. Taking advantage of the high detection efficiency and high spatial resolution of this technique, the x-ray source spot is characterized with a relative error of ∼5% in the full width at half maximum of the intensity profile in a single-shot mode for general laser parameters, which makes it possible to reveal the information of the unfixed spot size and position precisely. Our results show the necessity and feasibility of monitoring the spot of these novel laser-driven x-ray sources via the penumbral coded aperture imaging technique.

Bupivacaine induces reactive oxygen species production via activation of the AMP-activated protein kinase-dependent pathway.

AIMS: It was our aim to investigate whether AMP-activated protein kinase (AMPK) mediates the considerable increase in reactive oxygen species (ROS) and cell apoptosis induced by bupivacaine in the human neuroblastoma cell line SH-SY5Y. METHODS: The recombinant plasmids pGPU6/GFP/Neo-shRNA AMPKα2 and pEGFP-N1-AMPKα2 were constructed and transfected into the SH-SY5Y cell line. The expression of AMPKα2 was determined by RT-PCR and Western blot after transfection. The SH-SY5Y cells transfected with recombinant plasmid were exposed to 1 mmol/l bupivacaine. Cell viability, intracellular ROS and apoptosis were determined. RESULTS: The plasmid pEGFP-N1-AMPKα2 can upregulate the expression of AMPKα2, and the pGPU6/GFP/Neo-shRNA AMPKα2 can downregulate the expression of AMPKα2 in cells. Inhibition of AMPKα2 expression attenuated ROS production and cell apoptosis, and overexpression of AMPKα2 promoted ROS production and cell apoptosis after bupivacaine treatment. CONCLUSION: AMPK probably mediated ROS production and cell apoptosis induced by bupivacaine.

High Glucose Enhances Bupivacaine-Induced Neurotoxicity via MCU-Mediated Oxidative Stress in SH-SY5Y Cells.

Bupivacaine, a typical local anesthetic, induces neurotoxicity via reactive oxygen species regulation of apoptosis. High glucose could enhance bupivacaine-induced neurotoxicity through regulating oxidative stress, but the mechanism of it is not clear. Mitochondrial calcium uniporter (MCU), a key channel for regulating the mitochondrial Ca2+ (mCa2+) influx, is closely related to oxidative stress via disruption of mCa2+ homeostasis. Whether MCU is involved in high glucose-sensitized bupivacaine-induced neurotoxicity remains unknown. In this study, human neuroblastoma (SH-SY5Y) cells were cultured with high glucose and/or bupivacaine, and the data showed that high glucose enhanced bupivacaine-induced MCU expression elevation, mCa2+ accumulation, and oxidative damage. Next, Ru360, an inhibitor of MCU, was employed to pretreated SH-SY5Y cells, and the results showed that it could decrease high glucose and bupivacaine-induced mCa2+ accumulation, oxidative stress, and apoptosis. Further, with the knockdown of MCU with a specific small interfering RNA (siRNA) in SH-SY5Y cells, we found that it also could inhibit high glucose and bupivacaine-induced mCa2+ accumulation, oxidative stress, and apoptosis. We propose that downregulation expression or activity inhibition of the MCU channel might be useful for restoring the mitochondrial function and combating high glucose and bupivacaine-induced neurotoxicity. In conclusion, our study demonstrated the crucial role of MCU in high glucose-mediated enhancement of bupivacaine-induced neurotoxicity, suggesting the possible use of this channel as a target for curing bupivacaine-induced neurotoxicity in diabetic patients.

[Clinical analysis of 31 cases of traumatic interhemispheric subdural hematomas].

OBJECTIVE: To analyze the clinical characteristics, pathogenesis and management of traumatic interhemispheric subdural hematomas (ISH). METHODS: Thirty-one traumatic ISH cases were reviewed and analyzed retrospectively. RESULTS: Of the 31 patients, 29 were cured and 2 died of multi-system organ failure (MSOF) and cerebral hernia respectively. Typically, ISH manifested hemiplegia or paralysis of the counterlateral lower limb known as falx syndrome. CONCLUSIONS: CT scans showing hematocele in the interhemispheric subdural space in excess of 20 ml, or with a thickness of hematocele over 1cm, may serve as a diagnostic criteria for ISH. For the treatment of ISH, surgery and conservative management are suggested on the basis of functional disturbance or the stability of the disease.

[Therapeutic effect of L-arginine on traumatic shock in rats].

OBJECTIVE: To evaluate the therapeutic effect of L-arginine (L-Arg) on traumatic shock in rats and explore the possible mechanisms. METHODS: Rat models of traumatic shock were established in Sprague-Daulay rats, which were randomly divided into two groups either to receive L-Arg treatment or not. The plasma concentration of endothelin (ET) and oxygen partial pressure in the tissues from the skeletal muscles, liver and small intestine were measured before and after the shock and 1, 3, and 5 h after resuscitation. The hemodynamics of the rats and their survival rates at 12 and 24 h were recorded. RESULTS: The changes of plasma ET levels and oxygen partial pressure in tissues of both groups were statistically significant after traumatic shock (P<0.05). Plasma ET concentration at 5 h after resuscitation was significantly lower in the treatment group than in the non-treatment shock group (P<0.05), while oxygen partial pressure in the liver and small intestine after resuscitation were significantly higher in the treatment group (P<0.05). The survival rates at 12 and 24 h were also significantly different between the 2 groups. CONCLUSION: Adscititious L-Arg can decrease plasma ET levels, improve oxygen partial pressure of internal organs and significantly increase the survival rate of the rats with traumatic shock.

Bupivacaine induces apoptosis via mitochondria and p38 MAPK dependent pathways.

Mitochondria and the p38 mitogen-activated protein kinase (MAPK) pathways play important roles in apoptosis. Although the effect of bupivacaine on apoptosis is known, it remains unclear whether bupivacaine induces apoptosis via mitochondrial depolarization and the p38 MAPK activity. In this study, SH-SY5Y cells were pretreated respectively with 50µM 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid (DIDS), 10µM 4-(4-Fluorophenyl)-2-[4-(methylsulfinyl)phenyl]-5-(4-pyridyl)-1H-imidazole (SB203580), and 50µM DIDS plus 10µM SB203580 30min prior to the treatment with either 1mM bupivacaine or an equivalent amount of medium. The cell viability, mitochondrial membrane potential, phospho-p38 MAPK (p-p38 MAPK) and cell apoptosis were investigated with MTT assay, western blots, Hoechst 33258 staining and flow cytometry assay. In addition, the roles of chloridion (Cl(-)) channel and reactive oxygen species were studied to explore the molecular mechanism of bupivacaine-induced mitochondrial injury. Pretreatment with DIDS could attenuate reactive oxygen species production, the phosphorylation of p38MAPK, dissipation of mitochondrial membrane potential and apoptosis of SH-SY5Y cells induced by bupivacaine. Pretreatment with SB203580 could attenuate apoptosis, but could not attenuate reactive oxygen species production, or dissipation of mitochondrial membrane potential induced by bupivacaine. These findings indicate that the mitochondrial anion channel and p38 MAPK pathway are implicated in bupicavaine-induced apoptosis. Bupivacaine-induced reactive oxygen species production results in an alteration in the permeability of the mitochondrial membranes and Cl(-) influx into mitochondria, which seems to be responsible for mitochondrial depolarization and the p38 MAPK activation.

[Identification and expression of shRNA vectors targeting human AMPKα2].

OBJECTIVE: To construct pGPU6/GFP/Neo-shRNA expression vector targeting human AMPKα2 gene and evaluate its silencing effect in SH-SY5Y cell line. METHODS: The oligonucleotides designed by Ambion online CAD software targeting AMPKα2 were cloned into the pGPU6/GFP/Neo vector. After confirmation by DNA sequencing and enzyme digestion analysis, the recombinant vectors were transfected into the SH-SY5Y cell line via lipofectamine and the positive clones were selected using G418. The expression levels of AMPKα2 mRNA and protein in the transfected cells were detected by RT-PCR and Western blotting, respectively. RESULTS: Four shRNA vectors were successfully constructed as confirmed by DNA sequencing and the enzyme digestion analysis. Among the 4 recombinant vectors, pGPU6/GFP/Neo-shRNA AMPKα2(3) showed the strongest gene silencing effect and down-regulated the protein expression of AMPKα2 by 63% in the transfected cells. CONCLUSION: Transfection with pGPU6/GFP/Neo-shRNA AMPKα2(3) results in effective inhibition of AMPKα2 gene expression in SH-SY5Y cells, which provide a means for studying AMPK-mediated cell injury.