Excitation and axonal flow: Autoradiographic study on motoneurons intracellularly injected with a 3H-amino acid

Summary Tritiated glycine has been injected intracellularly into cat motoneurons by means of cross barrel iontophoresis through microelectrodes. The amino acid is incorporated into proteins in the cell body and the synthesized radioactive proteins have been localized by autoradiography. The single-cell-injection technique has several advantages over the usual intraperitoneal, intravenous or intrathecal injection, e.g. distribution of the radiochemical is strictly confined to the injected neuron; the amount of injected substance can be estimated; it is easy to investigate simultaneously electrophysiological and morphological characteristics of a defined neuron. Since the injected cell body releases radioactive proteins into the axon, the transport of these substances can be studied under various conditions.In this study the influence of antidromic stimulation has been studied. Stimulated motoneurons demonstrate higher radioactivity in their cell bodies than unstimulated ones, reflecting an increased protein synthesis. The differences are even more pronounced in the axons of stimulated cells when compared with unstimulated ones. A significant, higher amount of radioactive material — up to 100% increase as demonstrated by silver grain counting — can be seen in the axons of stimulated neurons. Although considerable differences seem to exist for the quantity of the exported proteins no significant differences have been detected for the velocity of transportation. In axons of stimulated and unstimulated neurons proteins advance toward the periphery at the same rate.     

Excitation and depression of cortical neurones during spreading depression

Summary Variations in the excitability of individual cortical neurones during the invasion of spreading depression (SD) have been monitored by observing the alterations of spontaneous and L-glutamate-induced firing. Invasion of many neurones during SD is marked by a brief burst of firing which occurs concurrently with the onset of the negative slow extracellular potential. Other neurones do not fire, although the microelectrode records a negative slow wave. Depression of glutamate-induced and spontaneous firing follows and may last for several minutes. The initial loss of excitability of those neurones that discharge during SD invasion may be due to excessive depolarization. This phase is rapidly succeeded by a period of depressed excitability, during which the neurones can be invaded by an antidromic spike or excited by increased amounts of L-glutamate. These findings indicate that SD propagation initially involves the release of an excitant substance, possibly glutamic acid. The continuing effects of SD are due to the reduction in cell excitability. As many neurones are depressed without undergoing an initial excitation, it appears that a depressant substance is also involved. This may be gamma-aminobutyric acid.     

Divergent neuroendocrine responses to localized and systemic inflammation

The sympathetic nervous system (SNS) is part of an integrative network that functions to restore homeostasis following injury and infection. The SNS can provide negative feedback control over inflammation through the secretion of catecholamines from postganglionic sympathetic neurons and adrenal chromaffin cells (ACCs). Central autonomic structures receive information regarding the inflammatory status of the body and reflexively modulate SNS activity. However, inflammation and infection can also directly regulate SNS function by peripheral actions on postganglionic cells. The present review discusses how inflammation activates autonomic reflex pathways and compares the effect of localized and systemic inflammation on ACCs and postganglionic sympathetic neurons. Systemic inflammation significantly enhanced catecholamine secretion through an increase in Ca²⁺ release from the endoplasmic reticulum. In contrast, acute and chronic GI inflammation reduced voltage-gated Ca²⁺ current. Thus it appears that the mechanisms underlying the effects of peripheral and systemic inflammation neuroendocrine function converge on the modulation of intracellular Ca²⁺ signaling.     

Densities of glutamatergic and GABAergic presynaptic terminals are altered in experimental cortical dysplasia

Purpose: Cortical dysplasia (CD) is a major cause of epilepsy in children and adults, but underlying mechanisms of epileptogenesis in this disorder are poorly understood. We have utilized the irradiated rat model to study an injury‐based form of diffuse CD in rats. Prior studies in this model have shown reduced numbers of γ‐aminobutyric acid (GABA)ergic interneurons and reduced inhibitory synaptic currents in pyramidal cells in CD. We analyzed the number of excitatory and inhibitory presynaptic terminals in the neocortex of irradiated rats to better characterize altered connectivity in experimental CD. Methods: Antibodies to vesicular glutamate transporter 1 (VGLUT1), vesicular glutamate transporter 2 (VGLUT2), vesicular GABA transporter (VGAT), and parvalbumin (PV) were used to quantify glutamatergic and GABAergic presynaptic terminals in control and dysplastic cortex. Results: We found that the density of VGLUT1 terminals was increased in CD in comparison to layers IV, V, and VI in control cortex. VGLUT2 terminals were increased in CD compared to layers IV and VI. VGAT terminals were reduced in CD compared to layers II/III, IV, and V in controls as were PV‐immunoreactive somata and terminals. Discussion: These findings suggest an overall increase in excitatory synaptic connectivity and decrease in inhibitory synaptic connectivity in CD in irradiated rat. We propose that these changes contribute to hyperexcitability in these animals and may contribute to epileptogenicity in some forms of human CD.     

The SAC/SAC-CI studies of ground and low-lying electronic excited states of OClO,OClO and OClO

The properties of the ground and low-lying electronic excited states of OClO, OClO⁺ and OClO⁻ are studied employing symmetry-adapted-cluster (SAC)/symmetry-adapted-cluster configuration interaction (SAC-CI) method. The geometry of the ground state of OClO is optimized by SAC method using different basis sets and the reasonable geometry of the ground state of OClO is obtained by SAC/6-311++G (2d, 2p) level. The properties of nine low-lying electronic excited states of OClO, such as geometries, vertical excitation energies, adiabatic excitation energies, transition dipole moments and oscillation strengths, are studied at SAC-CI method. By SAC-CI/6-311++G (2d, 2p) level, the geometries of ten electronic states of OClO⁺ are optimized and the adiabatic ionization potentials (AIP) and the vertical ionization potentials (VIP) of OClO⁺ are calculated. The geometries of six electronic states of OClO⁻ are optimized and the vertical detachment energies (VDE) and adiabatic detachment energies (ADE) of OClO⁻ are obtained. Comparing with the available experimental and previous theoretical data, the SAC/SAC-CI/6-311++G (2d, 2p) results are reliable.     

自体荧光光谱检测胃浆膜识别胃癌组织

目的探讨自体荧光光谱从胃浆膜识别胃癌的可行性,为手术中准确确定胃癌切除范围奠定基础。方法选用激光源Xe灯的308、337、365和405nm14种激发波长测试和比较了41例患者胃癌、癌旁、正常处胃浆膜的自体荧光光谱。结果405nm激发正常组、癌旁组、胃癌组的单主峰强度依次减弱(P<0.05),可依此区分3组标本。胃癌组在610-630nm存在卟啉特征峰,胃癌组明显高于正常组(P<0.01);365nm激发可识别胃癌与正常组,但不能区分癌旁组(P>O.05);337YIITI、308niql激发从正常组到胃癌组双主峰强度逐步成相反的变化趋势,双峰强度比可有效区分3组标本,但308nm激发(P<0.01)比337nm激发(P<0.05)的可区分度更高。结论4种波长激发均能区分正常胃浆膜与胃癌浆膜,其中308nm、337nm、405nm激发的荧光光谱能更灵敏地区分胃癌、癌旁及正常胃浆膜,308nm的效果最好。     

Excitation mapping with the organic cation AGB

Excitation mapping is a method of visualizing the signaling history of neurons with permeant organic cations. It is compatible with high-resolution imaging, allowing concurrent visualization of all neuronal classes and their glutamate-gated excitation histories. Excitation mapping documents the stability and precision of neuronal signaling within a given neuronal class, arguing that single unit electrophysiological sampling accurately reflects neuronal diversity. We here review the theory of excitation mapping, provide methods and protocol links; outline imaging concepts; provide parametric data on the temporal range and physiological sensitivity of excitation mapping; and show that immunocytochemical methods for macromolecules are compatible with excitation mapping.     

Electromechanical delay is a key to neuromuscular transmission北大核心

BACKGROUND: With the development of sports medicine and rehabilitation medicine, electromechanical delay has been looked as an important index for evaluating the neuromuscular function at abroad. But the relevant research is little reported in China. OBJECTIVE: To review the literatures related to electromechanical delay published in recent years, and to explore the mechanisms, influential factors and the application status of the electromechanical delay, thereby providing reference for clinical practice and research. METHODS: A computer-based search of CNKI, WanFang and PubMed databases was performed for articles addressing electromechanical delay published from February 1979 to February 2017. The keywords were ”electromechanical delay, electro-mechanical response time” in English and Chinese, respectively. Repeated and old studies were excluded, and finally 44 eligible literatures were included, including 3 Chinese and 41 English articles. RESULTS AND CONCLUSION: The mechanisms of electromechanical delay have been clarified. The type of muscle fiber and the level of muscle fatigue can influence electromechanical delay, but the underlying mechanisms still remain unclear. Whether age and gender make effect on electromechanical delay is controversial. Electromechanical delay is not only used for evaluating the athletes’ ability to reaction, but also wildly used to investigate the mechanism of various sports injuries and evaluate the effectiveness of rehabilitation. © 2017, Journal of Clinical Rehabilitative Tissue Engineering Research. All rights reserved.     

A comparison of sexually explicit illustrations for use in psychosexual therapy

This quantitative study aimed to establish patients' preferred illustrations for educative use in psychosexual therapy by comparing their responses to photographs and line drawings both depicting sexual activity. A sample of 68 subjects, divided almost equally between the sexes and between the age groups 18-40 and 41-65, attending a sexual difficulties clinic at the Porterbrook Clinic, Sheffield were recruited. Nearly all subjects felt comfortable with both types of illustration and thought that they were helpful. Roughly 70% of subjects favoured photographs over line drawing as being the most informative and useful, and most appealing. However, preference was reversed when subjects were asked which illustrations were most acceptable for keeping at home, with 52% preferring line drawings. There were no significant differences between the age groups in their preference choices, in contrast to previous studies which have shown older subjects less accepting of sexually explicit material than younger people.