一种关于RPM放疗呼吸门控系统束流时间延迟性能的参考质控方法

目的：提出一种关于RPM放疗呼吸门控系统束流时间延迟性能的参考质控方法,给出参考条件下VB与EDGE加速器的时间延迟测量结果。方法：首先设计梯形质控呼吸曲线并加载运动模体,利用定位CT扫描由运动模体驱动的W-L模体,然后设计用于束流出束和截止延迟测量的两类质控计划,最后在加速器上执行质控计划,使用EPID采集模体的静态参考图像与运动测量图像,通过分析致密金属球在运动图像和参考图像中的位置差,反推束流的时间延迟,分别在VB与EDGE两台加速器上做方法验证。结果：VB与EDGE加速器的束流出束时间延迟均小于100 ms,截止时间延迟基本一致,VB加速器约为14 ms,EDGE约为22 ms。10FFF各剂量率的出束时间延迟基本一致,而6FFF、6 MV和10 MV则随剂量率的变化略有增加。4个能量各剂量率的束流截止时间延迟均较小且相对一致,部分能量有随剂量率变大而延迟缩小的趋势。结论：本研究提出的RPM束流时间延迟参考质控方法和条件具有较高的测量可信度和较强的临床实操性,测量结果表明RPM呼吸门控系统响应灵敏,研究结果为呼吸门控系统的时间延迟质控提供了重要的方法学指导与数据参考。     

Mechanisms of oral sensation

Sensory nerves that supply mechanoreceptors in the mucosal lining of the oral cavity, pharynx, and larynx provide the substrate for a variety of sensations. They are essential for the perception of complex or composite sensory experiences including oral kinesthesia and oral stereognosis. Relevant to the concerns of the oral health care delivery specialist they also contribute to initiation of reflexes and coordination and timing of patterned motor behaviors. The response of oral mechanoreceptors to natural stimuli is determined to a large degree by morphological factors such as the nature of the relationship between nerve ending and certain cellular specializations, their distribution in the mucosa, the diameter of their primary afferent nerve fibers, and the central distribution of these fibers in the brainstem. Because of morphological similarities to certain cutaneous mechanoreceptors, the mucosal lining may be considered as an internal continuation of the large receptor sheet for localization and detection of mechanical stimuli. In some regions of the oral, pharyngeal, and laryngeal mucosa, this analogy is appropriate whereas in others, existing data suggest a different role consistent with regionally specific demands (i.e., initiation of protective reflexes).     

离子通道门控动力学研究

报道作者近期在离子通道动力学方面所作的研究工作。以膜片钳记录信号的自相关函数为基础,证实了离子通道记忆性的存在,并提出两状态非线性随机模型和镶嵌点过程模型,用于描述记忆性和门控动力学的特征,这样做可以克服Ｍａｒｋｏｖ模型和分形模型所遇到的３项困难,即状态不可辨认性、开关判定的主观性和时间间隔疏漏。另外,作者还提出了连续分组平均时间检测法,帮助确定Ｍａｒｋｏｖ模型中状态的个数,与多指数拟合法相比,此方法更直观和易于操作     

Apoptotic cascade of neurons in the subcortical sensory relay nuclei following the neonatal infraorbital nerve transection

A terminal transferase-mediated dUTP nick end labeling (TUNEL) method was utilized for detection of neuronal death in the subcortical relay nuclei of the trigeminosensory system following the infraorbital nerve transection in newborn rats. At 18-24 h after injury, numerous TUNEL-positive profiles were found within the ventroposteromedial thalamic nucleus (VPM) contralateral to the injury, whereas the VPM on the ipsilateral side and of the age-matched normal control contained only a few profiles per section. Electron microscopy revealed that the TUNEL-positive profiles were apoptotic neurons. The ventral part of the ipsilateral brainstem sensory trigeminal nuclear complex (the nucleus principalis, and the subnuclei oralis and interpolaris) exhibited statistically significant 65-70% increase in number of apoptotic neurons compared to the contralateral side. Taken together with our previous study [T. Sugimoto, C. Xiao, H. Ichikawa, Neonatal primary neuronal death induced by capsaicin and axotomy involves an apoptotic mechanism, Brain Res. 807 (1998) 147-154], the present results demonstrated a cascade of apoptosis in the primary, secondary and tertiary order sensory neurons along the neuroaxis.     

Localization of verotoxin receptors in nervous system

We use immunohistochemistry to show the existence of verotoxin receptor in small sensory neurons in DRG of human, rabbit, rat and mouse. In capillary in nervous system, the verotoxin receptor exists in human and rabbit, but the receptor could not be demonstrated in rat and mouse, by this method. The receptors in sensory neuron of rat and in capillary in rabbit brain are determined as galactosylglobotriaosylceramide (GalGb3) and globotriaosylceramide (Gb3,), respectively. Although verotoxin was reported to bind to glycolipid receptors that possess the terminal disaccharide Galalpha1-4Galbeta (galactobiose), the binding to toxin to galabiosylceramide was half of that of GalGb3 which has galactobiose internally.     

Development of weakness in patients with chronic inflammatory demyelinating polyneuropathy and only sensory symptoms at presentation: A long-term follow-up study

This long-term follow-up study examined patients with chronic inflammatory demyelinating polyneuropathy (CIDP) and only sensory symptoms at first presentation, with emphasis on the development of motor symptoms and long-term disability. From all CIDP patients referred to our Department between 1987 and 1995, seven had only sensory symptoms at first clinical presentation. These were investigated according to a standard protocol, including a quantified clinical neurological examination and nerve conduction studies. The mean duration of the disease before weakness developed was 3.1 years, but varied considerably (0.8–6.3 years). At follow-up, weakness developed in five patients and persisted in three of them. Five patients were not seriously incapacitated by their disease (Rankin 1 or 2), four of them being in remission now and one showing a very slow progression of disease. Two patients were moderately disabled (Rankin 3); one had severe persistent sensory ataxia and only weakness during relapses and one had stepwise progression and moderate weakness. Motor nerve conduction studies revealed that the most notable worsening in the entire group of patients was a decrease in distal compound muscle action potential amplitudes, indicating the development of distal conduction block or axonal degeneration. These findings show that CIDP with only sensory symptoms is a transient clinical stage that precedes the appearance of weakness in about 70% of patients. The long-term prognosis does not differ from that of patients with CIDP who have weakness at the beginning of the disease. Received: 3 December 1998 Received in revised form: 17 May 1999 Accepted: 2 July 1999     

Ca2+ activation of hSlo K+ channel is suppressed by N-terminal GFP tag

The human slow poke (hSlo) K+ channel was tagged with GFP (green fluorescent protein) at the N-terminus of its alpha-subunit. The fusion protein was expressed transiently in HEK293 cells; it formed functional voltage-gated channels as shown by whole cell patch-clamp measurements. However, the tag lowered the voltage dependence of gating and it suppressed the typical left-shift of gating by intracellular binding of Ca2+. The location of the GFP-tagged N-terminus was confirmed to be on the extracellular side by application of a monoclonal antibody to nonpermeabilized cells. Structural interpretations of the effects are discussed.     

Inflammation-induced changes in peripheral glutamate receptor populations

The ionotropic glutamate receptors N-methyl-d-aspartate (NMDA), alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) and kainate (KA) have been localized on subpopulations of unmyelinated and myelinated sensory axons in normal skin. Behavioral studies indicate that activation of these receptors results in nociceptive behaviors and contributes to inflammatory pain. The goal of the present study was to determine if these glutamate receptors might contribute to the peripheral hypersensitivity observed in inflammation. The major findings were that 48 h following complete Freund's adjuvant (CFA)-induced inflammation, the proportions of unmyelinated axons labeled for NMDA, AMPA or KA receptors were 61%, 43% and 48%, respectively, in cutaneous nerves in the inflamed paw compared to 48%, 22% and 27%, respectively, in the non-inflamed paw. The proportions of myelinated axons labeled for NMDA, AMPA or KA receptors were 61%, 61% and 43%, respectively, compared to 43%, 42% and 28%, respectively, in the non-inflamed hindpaw. These increases were all significant. These data indicate that the number of sensory axons containing ionotropic glutamate receptors increases during inflammation, and this may be a contributing factor to peripheral sensitization in inflammation.     

The timing of galvanic vestibular stimulation affects responses to platform translation

We compared the effects of galvanic vestibular stimulation applied at 0, 0.5, 1.5 and 2.5 s prior to a backward platform translation on postural responses. The effect of the galvanic stimulation was largest on the final equilibrium position of the center of pressure (CoP). The largest effects occurred for the 0.5 and 0-s pre-period, when the dynamic CoP pressure changes in response to both the galvanic stimulus and the platform translation coincided. The shift in the final equilibrium position was also larger than the sum of the shifts for the galvanic stimulus and the platform translation alone for the 0.5 and 0-s pre-periods. The initial rate of change of the CoP response to the platform translation was not significantly affected in any condition. Changes in the peak CoP position could be accounted for by local interaction of CoP velocity changes induced by the galvanic and translation responses alone, but the changes in final equilibrium position could only be accounted for by a change in global body orientation. These findings suggest that the contribution of vestibulospinal information is greatest during the dynamic phase of the postural response, and that the vestibular system contributes most to the later components of the postural response, particularly to the final equilibrium position. These findings suggest that a nonlinear interaction between the vestibular signal induced by the galvanic current and the sensory stimuli produced by the platform translation occurs when the two stimuli are presented within 1 s, during the dynamic phase of the postural response to the galvanic stimulus. When presented at greater separations in time, the stimuli appear to be treated as independent events, such that no interaction occurs.     

Medial plantar nerve conduction velocities among patients with vibration syndrome due to chain-saw work

Objective: The present study examined the effect of the vibration syndrome (VS) on the peripheral nervous system in the lower extremities. Methods: Thirty-eight patients with VS due to previous exposure to vibration from chain-saw work and 55 age-matched controls were examined for sensory nerve conduction velocities in the medial plantar nerve (SCV-P). The patient group was divided into two subgroups, one with (n=19) and the other without vibration-induced white finger (VWF; n=19). Results: Analysis of variance of SCV-P for the three groups showed significant difference (F _2,89=10.65, P < 0.0001). A significant difference was found between the controls and the VWF⁺ group (P < 0.0001) but not between the controls and the VWF⁻ group (P=0.0508) by multiple comparison using Scheffe's method. Conclusion: These findings suggest that VS affects the peripheral nervous system function in the lower extremities via mediation of circulatory disturbance manifested as VWF. Received: 7 May 1998 / Accepted: 15 June 1999