Spatial arrangements of dorsal root ganglion cells after sciatic nerve crush

The present study explores 3D spatial arrangements of the A- and B-cells within the fifth lumbar dorsal root ganglion (DRG) of rat in order to test for differences after sciatic nerve crush (SNC). The pair correlation and cross-correlation functions were estimated through counting dipole probes superimposed on DRG sections. The data showed that the A- and B-cells were clustered at distances below 40 and 35 μm in sham-operated animals, respectively. These values were 35 and 25 μm in SNC animals. Beyond these distances, the cells of the control group were arranged neither clustered nor repulsed. The A- and B-cells showed a negative correlation (repulsion) at r = 270–290 μm and r = 100 in SNC ganglions, respectively. The plot of the cross-correlation function showed that the first maximum curve was r = 51 μm and 41 μm in sham-operated and SNC rats, respectively. The other differences were seen at r = 51–61 μm and r = 165 μm between cross-covariance of the cells. The “degree of order” for the A- and B-cells showed no significant difference and the low values of the two groups indicated the random distribution of cells in them.

Conclusion

The obtained data revealed that cellular spatial patterns in the dorsal root ganglion of the sciatic nerve crush were changed.     

Role of TRPM8 in dorsal root ganglion in nerve injury-induced chronic pain

Background

Chronic neuropathic pain is an intractable pain with few effective treatments. Moderate cold stimulation can relieve pain, and this may be a novel train of thought for exploring new methods of analgesia. Transient receptor potential melastatin 8 (TRPM8) ion channel has been proposed to be an important molecular sensor for cold. Here we investigate the role of TRPM8 in the mechanism of chronic neuropathic pain using a rat model of chronic constriction injury (CCI) to the sciatic nerve.

Results

Mechanical allodynia, cold and thermal hyperalgesia of CCI rats began on the 4th day following surgery and maintained at the peak during the period from the 10th to 14th day after operation. The level of TRPM8 protein in L5 dorsal root ganglion (DRG) ipsilateral to nerve injury was significantly increased on the 4th day after CCI, and reached the peak on the 10th day, and remained elevated on the 14th day following CCI. This time course of the alteration of TRPM8 expression was consistent with that of CCI-induced hyperalgesic response of the operated hind paw. Besides, activation of cold receptor TRPM8 of CCI rats by intrathecal application of menthol resulted in the inhibition of mechanical allodynia and thermal hyperalgesia and the enhancement of cold hyperalgesia. In contrast, downregulation of TRPM8 protein in ipsilateral L5 DRG of CCI rats by intrathecal TRPM8 antisense oligonucleotide attenuated cold hyperalgesia, but it had no effect on CCI-induced mechanical allodynia and thermal hyperalgesia.

Conclusions

TRPM8 may play different roles in mechanical allodynia, cold and thermal hyperalgesia that develop after nerve injury, and it is a very promising research direction for the development of new therapies for chronic neuroapthic pain.

     

Calyx and dimorphic neurons of mouse Scarpa's ganglion express histamine H3 receptors

Background  

Histamine-related drugs are commonly used in the treatment of vertigo and related vestibular disorders. The site of action of these drugs however has not been elucidated yet. Recent works on amphibians showed that histamine H3 receptor antagonists, e.g. betahistine, inhibit the afferent discharge recorded from the vestibular nerve. To assess the expression of H3 histamine receptors in vestibular neurons, we performed mRNA RT-PCR and immunofluorescence experiments in mouse Scarpa's ganglia.     

Glycine receptors expression in rat spinal cord and dorsal root ganglion in prostaglandin E2 intrathecal injection models

Background

Glycine receptors (GlyRs) are involved in the development of spinal pain sensitization. The GlyRα3 subunit has recently emerged as a key factor in inflammatory pain pathways in the spinal cord dorsal horn (DH). Our study is to identify the extent of location and cell types expressing different GlyR subunits in spinal cord and dorsal root ganglion (DRGs). To tease out the possible actions of GlyRs on pain transmission, we investigate the effects produced by GlyRs on acute inflammatory pain by behavioral testing using prostaglandin E2 (PGE2) intrathecal injection models. Furthermore, we investigate the changes of GlyR expression in DRGs and spinal cord in rats after the induction of acute inflammatory pain.

Results

Compared to the vehicle administration, the PGE2 intrathecal injection model produced significantly higher hyperalgesia, which started 3 h after PGE2 injection and lasted more than 5 h. PGE2 intrathecal injection significantly decreased GlyRα1 and GlyRα3 protein expressions in the L5 DH at 1 h and lasted to 5 h, and similar results were observed in the L5 DRG at 5 h. Confocal microscopic images showed the co-existence of punctate gephyrin and GlyRα3 immunoreactivity (IR) throughout the gray matter of the spinal cord, mainly in DH laminae I–III neurons and in ventral horn neurons. It also showed the co-existence of punctate gephyrin and GlyRα3 IR in DRG neurons.

Conclusions

In this study, PGE2 intrathecal injection significantly decreased protein expression of gephyrin, GlyRα1 and GlyRα3 in spinal cord DH and DRG. The gephyrin and GlyRα3 were localized on neuron cells both in the DH and DRG.

     

Inducible gene inactivation in neurons of the adult mouse forebrain

Background  

The analysis of the role of genes in important brain functions like learning, memory and synaptic plasticity requires gene inactivation at the adult stage to exclude developmental effects, adaptive changes or even lethality. In order to achieve temporally controlled somatic mutagenesis, the Cre/loxP-recombination system has been complemented with the tamoxifen-inducible fusion protein consisting of Cre recombinase and the mutated ligand binding domain of the human estrogen receptor (CreER^T2). To induce recombination of conditional alleles in neurons of the adult forebrain, we generated a bacterial artificial chromosome-derived transgene expressing the CreER^T2 fusion protein under control of the regulatory elements of the CaMKIIα gene (CaMKCreER^T2 transgene).     

Visualization of collagen regeneration in mouse dorsal skin using second harmonic generation microscopy

The purpose of this study is to highlight a clearer understanding of the process of collagen regeneration during wound healing. By means of second harmonic generation (SHG) microscopy, the changes of collagen arrangement at the wound margin were analyzed at 0, 3, 5, 7, 11 and 13 days post injury. The degree of collagen disorders associated with the healing process was quantitatively obtained using the aspect ratio of polar plot image of collagen azimuthal angles and the healing status of collagen could be estimated by arithmetical mean deviation (Ra) of the collagen SHG images. Our results suggest that SHG microscopy has potential advances in the collagen studies during wound healing and the arrangement of collagen fibers gradually transformed from disorder to order so as to contract the wound. It is capable of promoting clinical application of the noninvasive imaging tool and the analysis methods of collagen disorder as an effective scar management for prevention and treatment about aberrant healing. Original Text ? Astro, Ltd., 2009. The article is published in the original.     

一种抗光干扰光幕靶的设计与改进

提出一种抗光干扰光幕靶的设计方法。当光幕靶工作于近炮口距离时,炮口火光会影响光幕靶产生误触发信号,从而影响测试系统的准确度。设计利用了光电器件阵列对火光同时反映的特点,设计光电补偿部件及前置放大减法器,将火光引起的变化的光电流信号抵消掉。分析了设计原理,并用实弹射击的方法验证了电路设计的正确性。     

A mathematical model for a single screen barrier in open-plan offices

In open-plan offices, single screen barriers are widely used to separate individual workplaces as a means of improving acoustical privacy. In this paper, a general model for calculating the insertion loss of a single screen barrier in the presence of a floor and a ceiling is developed using the image source technique. In addition to the acoustical properties of the floor and ceiling, this model also takes the sound absorption of the screen, the sound transmission through the screen and the interference between the sound waves into account. This model is able to separate the contribution of reflected sound and diffracted sound from the total sound pressure level at the receiving point, which can help indicate how best to improve the acoustical design of an open office. The mean differences between the predicted 1/3 octave band insertion loss values behind the screen and the corresponding measured results are within 2 dB.     

A further study of a mathematical model for a screen in open-plan offices

In order to obtain a good acoustical environment in open-plan offices, the acoustic performance of a single screen needs to be well estimated. Based on the sound pressure or the sound energy summation, the models proposed by previous investigators provided the predictions of the speech intelligibility index (SII) at the receivers behind a single screen in the open-plan offices. In the development of these models, the expression describing the diffracted field of a screen was an empirical formula and the sound diffraction is assumed to be appeared in the shadow region of the screen. In the present study, the MacDonald analytical formula is applied to describe the diffracted field of a screen, and both the diffractions in the visible region and in the shadow region are considered in the proposed model though it seems that the diffraction in the visible region is small compared with that in the shadow region. The comparison of the predicted and experimental results of the Wang and Bradley and the predicted results of the improved model shows that the improved model can provide a more accurate prediction, and further calculations indicate that the improvement is mostly due to the application of the MacDonald analytical diffraction formula.     

Genomics-based screening of differentially expressed genes in the brains of mice exposed to silver nanoparticles via inhalation

Silver nanoparticles (AgNP) are among the fastest growing product categories in the nanotechnology industry. Despite the importance of AgNP in consumer products and clinical applications, relatively little is known regarding AgNP toxicity and its associated risks. We investigated the effects of AgNP on gene expression in the mouse brain using Affymetrix Mouse Genome Arrays. C57BL/6 mice were exposed to AgNP (geometric mean diameter, 22.18 ± 1.72 nm; 1.91 × 10⁷ particles/cm³) for 6 h/day, 5 days/week using the nose-only exposure system for 2 weeks. Total RNA isolated from the cerebrum and cerebellum was subjected to hybridization. From over 39,000 probe sets, 468 genes in the cerebrum and 952 genes in the cerebellum were identified as AgNP-responsive (one-way analysis of variance; p < 0.05). The largest groups of gene products affected by AgNP exposure included 73 genes in the cerebrum and 144 genes in the cerebellum. AgNP exposure modulated the expression of several genes associated with motor neuron disorders, neurodegenerative disease, and immune cell function, indicating potential neurotoxicity and immunotoxicity associated with AgNP exposure. Real-time PCR data for five genes analyzed from whole blood showed good correlation with the observed changes in the brain. Following rigorous validation and substantiation, these genes may assist in the development of surrogate markers for AgNP exposure and/or toxicity.     

Identification of a set of genes showing regionally enriched expression in the mouse brain

Background

We have recorded responses from single neurons in murine visual cortex to determine the effectiveness of the input from the two murine cone photoreceptor mechanisms and whether there is any unique selectivity for cone inputs at this higher region of the visual system that would support the possibility of colour vision in mice. Each eye was stimulated by diffuse light, either 370 (strong stimulus for the ultra-violet (UV) cone opsin) or 505 nm (exclusively stimulating the middle wavelength sensitive (M) cone opsin), obtained from light emitting diodes (LEDs) in the presence of a strong adapting light that suppressed the responses of rods.

Results

Single cells responded to these diffuse stimuli in all areas of striate cortex. Two types of responsive cells were encountered. One type (135/323 – 42%) had little to no spontaneous activity and responded at either the on and/or the off phase of the light stimulus with a few impulses often of relatively large amplitude. A second type (166/323 – 51%) had spontaneous activity and responded tonically to light stimuli with impulses often of small amplitude. Most of the cells responded similarly to both spectral stimuli. A few (18/323 – 6%) responded strongly or exclusively to one or the other spectral stimulus and rarely in a spectrally opponent manner.

Conclusion

Most cells in murine striate cortex receive excitatory inputs from both UV- and M-cones. A small fraction shows either strong selectivity for one or the other cone mechanism and occasionally cone opponent responses. Cells that could underlie chromatic contrast detection are present but extremely rare in murine striate cortex.     

A comprehensive analysis of the electric field distribution in an electrodynamic screen

The electrodynamic screen, or EDS, has shown promising results in mitigation of dust accumulation losses in solar energy harvesting systems. In this paper, the electric field distributions in two EDS configurations have been thoroughly investigated. The analytical solutions for the electric potential and electric field distribution in the first EDS configuration have been provided and corroborated numerically using finite element analysis (FEA) software. The electrostatic model of second EDS configuration has been developed in the FEA software and its electric field distribution has been analyzed numerically. A comparison has been made between the two configurations regarding dust removal efficiency.     

A novel methodology for photometric compensation of projection display on patterned screen

We propose a novel methodology based on the projector-camera (ProCam) system to address the photometric compensation issue for the projection display on the patterned screen.The patterned screen is treated as the combination of a perfect white screen and a color modulator.The perfect white screen is used to automatically and accurately characterize the ProCam system offline using the polynomial model,and the parameters of the color modulator can be efficiently recovered by employing only two gray images based on the linear reflectance model.The experimental results show that the color artifacts of the display image can be greatly improved with this methodology,which demonstrates its feasibility and validity in the photometric compensation.     

一种大面积抗干扰高射频激光光幕靶设计

提出了一种能同时测量高射频火炮射击速度和密集度的大面积激光光幕靶设计方案。采用半导体激光脉冲调制、光电传感器列阵接收和单片机数字处理技术,不仅实现了光靶与计时系统一体化,而且有效地去除诸如炮口闪光、外界自然光及蚊虫等干扰,提高了测量的灵敏度、精度和可靠性。     

基于广义线性模型的针刺足三里脊髓背根神经活动解码

神经系统以时空编码形式刻画外部刺激信息, 针刺作为对穴位的机械作用可以等效为对神经系统的一种外部刺激. 为了揭示神经系统如何表达和传递针刺作用, 本文设计了不同频率的针刺动物实验, 即在针刺大鼠足三里穴位时获取脊髓背根神经节电信号. 首先, 经过数据预处理获得单神经元动作电位序列并转化为点过程序列. 其次, 应用广义线性模型(GLM)编码针刺作用, 产生模拟的神经放电序列. 另外, 在模型基础上应用贝叶斯解码, 根据神经放电序列重构针刺随时间变化的位移波形. 最后, 基于时间重标度理论应用分位数分位数(Q-Q)图方法检验编码模型与点过程数据的一致性. 结果表明, GLM能够模拟针刺神经编码, 并正确解码针刺信息. 本文为针刺研究提供了新的视角, 对于构建神经系统与机器接口以改善针刺的临床研究具有潜在意义. 关键词： 针刺 点过程 广义线性模型 神经解码