Differences between pattern onset and pattern reversal retinal responses

The pattern-evoked electroretinogram was recorded to pattern onset-offset and pattern reversal stimuli in two color-normal subjects with either luminance contrast of black-red (600 nm) and black-green (526 nm) square-wave stripe patterns or color contrast red-green patterns. The size of the onset response shows a spatial tuning with luminance contrast patterns and only a simple low-pass filter function with color contrast patterns. The peak latency of the response to luminance contrast increases with increasing spatial frequency but stays constant with color contrast patterns. The size of the reversal responses, however, shows only a low-pass filter function under both contrast conditions. The peak latency to luminance contrast shows a slight increase and to color contrast it remains constant with increasing spatial frequency. The differences noted under the various stimulus conditions must take into account the possible effects of different luminance modulation depths of onset and reversal stimuli, the modulation transfer function of the eye, and the activity of luminance-antagonistic and color-antagonistic receptive fields.     

Sleep tonus inversion: a feature of juvenile dystonic parkinsonism

Polysomnographic monitoring of a 16-year-old girl suffering from dopa-responsive dystonic parkinsonism showed a change in the distribution of muscle activity in thigh muscles during different stages of sleep. The hamstring muscles were hypertonic at sleep onset compared with the vastus lateralis of the quadriceps muscles. At the third sleep cycle of each of the 2 nights, the time at which sleep benefit becomes clinically evident, the hypertonia in the hamstring muscles was reversed and the vastus lateralis became more hypertonic. It is suggested that the muscle tonus inversion marks the moment at which the sleep process alleviates the dystonic parkinsonian state manifested at wakefulness as a circardian fluctuation. According to our data, the flexor-extensor tonus inversion during sleep was not yet described in the literature, and may be an associated feature of dopa-responsive dystonic parkinsonism.     

The role of OKT3 in clinical transplantation

OKT3 is a murine monoclonal anti-T cell antibody that is directed to CD3, a five-chain molecular complex found in association with the T cell receptor for antigen. OKT3 was the first monoclonal antibody to be used in organ transplantation and during the past 10 years there has been extensive experience of its use both for preventing and treating rejection in organ transplantation. OKT3 blocks T cell function by modulating CD3 and the T cell receptor from the T cell surface. A reaction to OKT3 results from cytokines released when OKT# first reacts with T cells. This reaction is generally mild but can be severe. First rejections following kidney transplantation are reversed in approximately 95% of cases. Steroid-resistant rejections are also susceptible to OKT3 but in only approximately 75% of cases. When used for prophylaxis, OKT3 completely blocks rejection in 95% of patients and significantly delays the onset of rejection in those who do reject. Antibodies to OKT3 are produced in approximately 75% of patients receiving it. However, seldom are the antibodies to OKT3 present in high titer and only in those cases is successful re-use of OKT3 prevented. As is the case with all potent immunosuppressive drugs, the use of OKT3 is associated with increased viral, specifically cytomegalovirus, infections. However, it appears that reduction of concomitant immunosuppression decreases the incidence of severe infections. Unquestionably, OKT3 has been a useful addition to the immunosuppression used for organ transplantation. In addition, its use has stimulated research on other monoclonal antibodies for use in organ transplantation.     

Gender Differences in Pattern Reversal Evoked Potentials in Normal Elderly

Pattern reversal evoked potentials (PREPs) were recorded in 51 normal elderly subjects (27 males. 24 females). Elderly females had shorter P100 and N150 latencies, greater P100-N150 amplitudes, and higher noise power than elderly males. The N150 latency differences were significant even when P100 latency effects were partialled out statistically. Gender differences in P100-N150 amplitude Mere independent of both noise power and PREP latency measures. These results provide evidence that, in the elderly, 1) gender differences in PREP amplitude reflect factors specific to CNS processing of visual stimuli rather than global CNS anatomic or physiological factors, 2) gender differences in P100 latency reported in younger groups are also present in the elderly, and 3) there are separable factors underlying gender differences in N150 and P100 latencies in the elderly.     

Visual evoked cortical and subcortical potentials in human albinos

Albinism is a congenital condition in which hypopigmentation occurs. In addition to this abnormality there is a misrouting of the optic nerve fibers, with some fibers from the temporal retina following a crossed route at the chiasma and terminating in the contralateral cortical hemisphere. This contralateral preponderance of fibers from each eye should be recognizable from recording the visual evoked cortical potential over each hemisphere on monocular stimulation. Such a technique should produce evidence of responses of either increased amplitude or shorter latency over the contralateral hemisphere. Twenty-five human albinos (twenty-three oculocutaneous, two ocular) have been examined. Pattern appearance-disappearance visual evoked cortical potentials were used, but only on bioccipital derivations did these show clear lateralization. With the flash response the P2 component has a consistently shorter latency over the contralateral hemisphere to the eye stimulated.The visual evoked subcortical potential shows contrasting lateralization. The implications of these findings are discussed.     

离体背根神经节细胞膜电学特性的测量及其应用

本文介绍了蟾蜍及新生大鼠离体背根神经节神经细胞膜电位及诱发动作电位的细胞内记录方法以及膜电导,翻转电位等电学特性的测量。应用上述方法测得蟾蜍DRG细胞膜输入电阻为30～40MΩ,新生大鼠的输入膜电阻为45～70MΩ;α_1肾上腺素能受体激活引起DRG细胞膜去极化反应时,膜电导减小.而α_2-肾上腺素能受体激活引起细胞膜电位超极化反应时,膜电导增加。去甲肾上腺素引起DRG细胞膜去极化反应的平均翻转电位值为-88.5mV。这些方法为神经细胞的某些电学特性、神经递质及受体等方面的研究提供了基本的实验手段。     

New insights into the molecular mechanisms of general anaesthetics

This paper provides new insights of how general anaesthetic research should be carried out in the future by an analysis of what we know, what we do not know and what we would like to know. I describe previous hypotheses on the mechanism of action of general anaesthetics (GAs) involving membranes and protein receptors. I provide the reasons why the GABA type A receptor, the NMDA receptor and the glycine receptor are strong candidates for the sites of action of GAs. I follow with a review on attempts to provide a mechanism of action, and how future research should be conducted with the help of physical and chemical methods.     

血栓闭塞性脉管炎动静脉造影23例观察和认识

对2(?)例血栓闭塞性脉管炎动静脉造影结果的分折,认为远端动脉病变为主,而静脉的改变是继发的,其闭塞仅限于肢端病损。因此,宜改变传统高位截肢,代之以尽可能多保留肢体长度为目的的动静脉转流术等方式的治疗方法。     

新斯的明早期拮抗维库溴胺的可行性研究

目的 :探讨新斯的明早期拮抗维库溴胺的可行性。方法 :选择ASAⅠ～Ⅱ级 ,拟在全麻下行择期手术病人 48例 ,随机分成维库溴胺组 1 6例 ,维库溴胺 +新斯的明组 3 2例 ,后者又按在维库溴胺使用后不同时间内使用新斯的明分为Ⅰ、Ⅱ两组 ,1 0min内为Ⅰ (n=1 6例 ) ,在 1 1～3 0min内为Ⅱ (n =1 6例 )。麻醉开始后全部病人单次给予维库溴胺1 .5mg·kg-1,当手术结束时维库溴胺组静脉注入生理盐水 8ml,维库溴胺 +新斯的明组注入新斯的明0 .0 5mg·kg-1+阿托品 0 .0 2mg·kg-1+生理盐水至8ml。观察、记录各组病人从注入维库溴胺至肌张力恢复到四个成串刺激 (TOF) 0 .2 5、0 .70的时间。结果 :各组病人肌张力恢复至TOF 0 .2 5、0 .70时间为维库溴胺组 (4 5 .5 8± 8.88)min、(67.5 9±5 .60 )min。维库溴胺 +新斯的明组Ⅰ (2 3 .45±2 .82 )min、(3 1 .86± 3 .3 6)min。维库溴胺 +新斯的明组Ⅱ (2 8.70± 4.1 3 )min、(3 8.86± 2 .1 0 )min。维库溴胺 +新斯的明组恢复时间明显短于维库溴胺组(P <0 .0 1 ) ,维库溴胺 +新斯的明组Ⅰ恢复时间又明显短于维库溴胺 +新斯的明组Ⅱ (P <0 .0 1 )。手术后进行连续监测未发现再次阻滞现象。结论 :新斯的明可以早期拮抗维库溴胺的肌松效应 ,同时也提示拮抗时间愈早 ,肌张力     

汉防己碱对白血病K562细胞生长的促进耐药作用

目的考察汉防己碱(Tet)对白血病K562细胞生长的影响。方法采用体外细胞培养,即在37℃、5%CO2、饱和湿度的培养箱中培养,培养液为含10%热灭活NBS的完全RPMI1640细胞培养基。待K562细胞与药物作用48 h后,收集并处理细胞,结合MTT和Western blot法研究Tet对K562细胞生长的作用特点。结果 Tet在0.33～1.00μg/ml仅使K562及K562/ADM细胞的存活率降低至75%～80%,低浓度Tet(0.33μg/ml)使阿霉素(ADM)和顺铂(cDDP)对K562细胞生长的IC50增加(P<0.01),1.0μg/ml Tet则降低IC50,使ADM对K562/ADM细胞的IC50增加,cDDP的IC50无明显变化。0.33μg/ml Tet有提升2种细胞的P-gp和MRP1表达的作用(P<0.05)。Tet各浓度对LRP表达无明显影响。结论 Tet对K562及K562/ADM细胞生长抑制作用具浓度依耐性,低浓度具加速耐药的作用,其促进耐药细胞发展的机制至少与提升P-gp和MRP1表达有关。