Regulation of single potassium channels by serotonin in the cell bodies of the tail mechanosensory neurons ofAplysia californica

Sensory neurons in the pleural ganglion ofAplysia mediate the afferent portion of the tail withdrawal reflex. Previous work has shown that in these neurons and in the siphon sensory neurons ofAplysia, serotonin modulates a steady-state non-inactivating potassium current called the S current. Using the technique of patch clamping, we have examined the kinetics of single potassium channels and found that they share the properties of the S potassium channel of the siphon sensory neurons. This channel has an elementary slope conductance of73 ± 9.98pS(x±S.E.M.) and shows Goldman rectification. It is active at the resting potential and does not inactivate with maintained depolarization. Bath application of serotonin in a majority of experiments decreased the functional number of channels in the patch.     

The effects of longitudinal chromatic aberration and a shift in the peak of the middle-wavelength sensitive cone fundamental on cone contrast

Longitudinal chromatic aberration is a well-known imperfection of visual optics, but the consequences in natural conditions, and for the evolution of receptor spectral sensitivities are less well understood. This paper examines how chromatic aberration affects image quality in the middle-wavelength sensitive (M-) cones, viewing broad-band spectra, over a range of spatial frequencies and focal planes. We also model the effects on M-cone contrast of moving the M-cone fundamental relative to the long- and middle-wavelength (L- and M-cone) fundamentals, while the eye is accommodated at different focal planes or at a focal plane that maximizes luminance contrast. When the focal plane shifts towards longer (650nm) or shorter wavelengths (420nm) the effects on M-cone contrast are large: longitudinal chromatic aberration causes total loss of M-cone contrast above 10-20c/d. In comparison, the shift of the M-cone fundamental causes smaller effects on M-cone contrast. At 10c/d a shift in the peak of the M-cone spectrum from 560 to 460nm decreases M-cone contrast by 30%, while a 10nm blue-shift causes only a minor loss of contrast. However, a noticeable loss of contrast may be seen if the eye is focused at focal planes other than that which maximizes luminance contrast. The presence of separate long- and middle-wavelength sensitive cones therefore has a small, but not insignificant cost to the retinal image via longitudinal chromatic aberration. This aberration may therefore be a factor limiting evolution of visual pigments and trichromatic color vision.     

Auxiliary subunits of the AMPA receptor: The Shisa family of proteins

AMPA receptors mediate fast synaptic transmission in the CNS and can assemble with several types of auxiliary proteins in a spatio-temporal manner, from newly synthesized AMPA receptor tetramers to mature AMPA receptors in the cell membrane. As such, the interaction of auxiliary subunits with the AMPA receptor plays a major role in the regulation of AMPA receptor biogenesis, trafficking, and biophysical properties. Throughout the years, various ‘families’ of proteins have been identified and today the approximate full complement of AMPAR auxiliary proteins is known. This review presents the current knowledge on the most prominent AMPA-receptor-interacting auxiliary proteins, highlights recent results regarding the Shisa protein family, and provides a discussion on future research that might contribute to the discovery of novel pharmacological targets of auxiliary subunits.     

调幅信号的数字解调及其在生理信号远程传输中的应用

利用数字采样系统的特性,克服了用数字方法解调调幅信号的固有困难,提出了一种新的数字方法来解调这类信号,由于生理信号的超低频分量相当丰富,利用电话网络无法直接传送。     

DR不同类型平板探测器性能的比较研究

目的：研究非晶态硒和非晶态硅平板探测器的性能,以便合理的购买和使用DR。方法：比较量子检测效率DQE和调制传递函数MTF。结果：在空间分辨率较低时,非晶硅平板探测器的DQE最高;相比于非晶硅平板探测器,非晶硒平板探测器具有最优的MTF值,但空间分辨率增加时,非晶硅平板探测器的MTF迅速下降,而非晶硒平板探测器仍能保持较好的MTF值。结论：目前还没有一款DQE和MTF都做得很高的平板探测器,在摄片中应根据不同的检查部位来选择不同类型平板探测器的DR。     

利用管电流自动调节技术降低常规头部CT的照射剂量

目的 探讨常规头部CT采用管电流自动调节技术(即TCM螺旋扫描模式)能否降低照射剂量和提高影像质量。方法 50例成人患者,分别接受常规头部CT的TCM螺旋和常规轴扫模式,常规轴扫参数:140 kV,170mA用于颅底部;120 kV,150 mA用于颅脑部,2s/周。TCM螺旋扫描参数:120 kV,280 mA(最大管电流阈值),0.8 s/周。扫描剂量直接取自设备剂量指示值(CTDI和DLP)。影像质量分别由两位专家采用双盲法,对头部CT的颅底、脑灰-白质层面以及全部影像逐层进行CT值、信噪比测量以及综合评估。结果 常规头部CT采用TCM螺旋扫描模式较轴扫模式可使患者有效降低管电流使用量(44±12)mA,扫描时间(4.8±0.8)s,照射剂量(38±0.9)%:[CTDI:(32.10±9.0)mGy、(55.00±7.2)mGy;DLP(442.10±72)mGy·cm、(668.00±26)mGy·cm];经计算人体吸收剂量可降低(1.5±0.4)mSv,并可有效提高影像质量。结论 经两种不同扫描模式所得影像的CT值测量结果及其他影像质量参数的对照,应用TCM螺旋扫描模式的影像质量完全可与轴扫描模式相媲美,同时具有可减少扫描时间和照射剂量的优越性。     

干眼对视网膜成像质量的影响

目的比较干眼患者与健康人眼视网膜成像质量的差异。方法前瞻性队列研究。连续收集北京同仁医院眼科门诊无眼部器质性病变的轻度干眼患者22例（22眼）,对照组20例（20眼）,进行视觉相关生存质量[眼表疾病指数（OSDI）问卷]、基础泪液分泌（Schirmer Ⅰ）试验、角膜荧光染色、泪膜破裂时间（BUT）等检查。使用双通道客观视觉质量分析系统（OQASⅡ）以0.5 s为时间间隔,在6 mm瞳孔直径下测量患者自然瞬目后10 s的调制传递函数（MTF）截止频率动态变化。对于同一组患者不同时间点的数据通过Greenhouse-Geisser（G-G）法校正后,采用重复测量方差分析比较。比较干眼组与对照组瞬目后10 s不同时间段的MTF截止频率均值和MTF截止频率进展指数并作Spearman相关性分析。结果对照组/干眼组的平均BUT为（10.80±1.61）s/（3.36±1.26）s（t=-12.27,P<0.01）;Schirmer Ⅰ试验为（12.75±3.89）mm/（7.95±2.52）mm（t=-2.74,P<0.01）;OSDI评分为12.86±9.71/30.96±15.45（t=4.42,P<0.01）。2组瞬目后0.0～2.5 s、>2.5～5.0 s、>5.0～7.5 s、>7.5～10.0 s MTF截止频率均值分别为对照组（21.23±9.38）、（20.98±8.72）、（21.12±9.38）、（20.11±8.28）c/d,干眼组（26.20±16.09）、（24.60±15.99）、（24.24±15.83）、（23.20±15.05）c/d,组间比较结果显示,2组患者在瞬目后相同时间段的MTF截止频率均值差异均无统计学意义;重复测量方差分析结果显示干眼组瞬目后4个时间段的组内MTF截止频率均值差异具有统计学意义（F=14.49,P<0.01）,对照组结果差异无统计学意义。MTF截止频率进展指数与性别（r=0.46,P<0.01）、logMAR最佳矫正视力（r=0.33,P<0.05）、BUT（r=0.34,P<0.05）呈正相关;与OSDI功能影响（r=-0.36,P<0.05）和OSDI总得分呈负相关（r=-0.31,P<0.05）。结论干眼患者与正常人相比,瞬目后单位时间内的视网膜成像质量下降幅度较大,并与患者的BUT和对日常活动影响程度相关。     

虹膜固定型人工晶状体植入矫正高度近视的疗效

目的探讨虹膜固定型人工晶状体（10L）植入术矫正高度近视的近中期安全性、有效性以及术后的视觉质量。方法前瞻性临床研究。双眼植入虹膜固定型10L患者89例,屈光度范围-6．00-24．00D。观察术前、术后3个月患者的裸眼视力（UCVA）、最佳矫正视力（BCVA）、角膜内皮计数、眼压（10P）,以及3、4、5mm瞳孑L直径下像差均方根（RMS）值、调制传递函数（MTF）值。术前术后各指标变化采用配对￡检验进行比较。结果178眼均一次性成功植入虹膜固定型IOL,术后随访2-48个月。术后裸眼视力达到或超过术前最佳矫正视力者占80％,且两者差异有统计学意义（t=6．187,P=0．003）。术后残余屈光度（-0-36±0．53）D。患者术后眼压与术前相比差异无统计学意义。术后角膜内皮计数较术前稍有下降,差异有统计学意义（f=2．690,B=0．01）。术后高阶像差与术前相比差异无统计学意义,所有瞳孔直径下的术后MTF值较术前稍有提高f5mm瞳孔直径下的高频空间除外）,且差异有统计学意义（P〈0．05）。结论虹膜固定型10L植入术矫正高度近视安全有效．具有可逆性、可预测性等优点．并能够提供较好的术后视觉质量。但是虹膜固定型10L对角膜内皮、晶状体、虹膜的远期影响还需进一步观察。     

5-Hydroxyindole potentiates human alpha 7 nicotinic receptor-mediated responses and enhances acetylcholine-induced glutamate release in cerebellar slices

The effects of 5-hydroxyindole (5-HI) have been investigated on human alpha 7 nicotinic acetylcholine receptors (nAChRs) expressed in Xenopus oocytes and GH4 cells, on native alpha 7 nAChRs expressed by IMR-32 cells and on alpha 7 nAChR-mediated events in mossy fibre-granule cell synapses in rat cerebellar slices. In oocytes expressing alpha 7 nAChRs, 5-HI potentiated sub-maximal, 60 micro M ACh-induced ion currents in a concentration-dependent manner, the threshold effective concentration being 30 micro M. 5-HI itself did not act as an agonist on alpha 7 nAChRs. A maximum potentiation of 12 times the control was observed at 20 mM 5-HI. The effect of 1 mM 5-HI on the concentration-response curve for ACh revealed that 5-HI increased the potency as well as the efficacy of ACh on alpha 7 nAChRs. 5-HI also potentiated alpha 7-mediated increases in intracellular free calcium levels in both mammalian cells heterologously expressing human alpha 7 nAChRs and in human IMR-32 neuroblastoma cells expressing native alpha 7 nAChRs. At mossy fibre-granule cell synapses, application of 1 mM ACh induced glutamate-evoked excitatory post-synaptic currents (EPSCs). Co-application of 1 mM 5-HI with 1 mM ACh further increased the frequency of the EPSCs. The ACh-induced release, as well as the 5-HI-induced enhancement of release, were blocked by 1-10 nM methyllycaconitine or 200 nM alpha-bungarotoxin, demonstrating that both effects were mediated by presynaptic alpha 7 nAChRs. The results demonstrate that responses mediated by alpha 7 nAChRs are strongly potentiated by 5-HI.