Calcium, network activity, and the role of NMDA channels in synaptic plasticity in vitro.

Functionally effective neuronal circuits are constructed through a competitive process that requires patterned neuronal activity elicited by structured input from the environment. To explore the mechanisms of this activity-dependent synaptic restructuring, we have developed an in vitro preparation of mouse spinal cord neurons maintained in a 3-chambered cell-culture system. Sensory afferents that received chronic electrical stimulation for 3-5 d developed stronger synaptic connections than unstimulated afferents converging onto the same postsynaptic spinal cord neuron. Exposure to 100 microM DL-2-amino-5-phosphonovaleric acid (APV), an antagonist of the NMDA channel, during the stimulation period prevented the competitive advantage associated with electric stimulation. However, when APV was applied with a higher concentration of calcium (3 mM), activity-dependent synaptic plasticity was no longer inhibited by the NMDA receptor antagonist. This reversal of APV block of the plasticity was not impaired by reducing transmitter release with 3 mM magnesium (in addition to 3 mM calcium and APV). A suppressant effect of APV on spontaneous activity was observed, which was attributed to loss of the NMDA component of the EPSP. Activity-dependent plasticity was also blocked if spontaneous activity was suppressed with dilute tetrodotoxin (TTX; 5-10 nM), a dosage that reduces excitability of neurons but is insufficient to block sodium-dependent action potentials. These experiments bring into question how NMDA channel activation is involved in the processes of synaptic remodeling during development. The data suggest that postsynaptic activity is required for synaptic remodeling, but this activity need not involve NMDA receptor activation specifically for activity-evoked synaptic plasticity. Instead, the mechanism for plasticity appears to operate through calcium-dependent processes in general.     

胞嘧啶脱氨酶的原核表达和多克隆抗体的制备

目的：在原核系统中表达并纯化大肠杆菌胞嘧啶脱氨酶（cytosine deaminase,CD)，制备鼠抗大肠杆菌CD多克隆抗体，方法：亚克隆CD基因到原核表达载体pMAL-c2和pBV222中，并转化入大肠杆菌DH5α内，诱导表达并纯化MBP-CD和6his-CD融合蛋白，用纯化的MBP-CD融合蛋白免疫小鼠制备多克隆抗体。结果：通过重组质粒的酶切筛选出重组阳性克隆，成功地表达和纯化出MBP-CD和6his-CD融合蛋白，用纯化的MBP-CD成功制备了鼠抗CD多克隆抗体，并用6his-CD和GST-CD重组蛋白进行Western印迹分析，证实了抗体的正确性，结论：应用多克隆抗体可以检测体内外CD基因的表达，为临床前和临床上深入开展CD基因的生物治疗研究提供重要的实验材料。     

影像学检查在儿童过敏性紫癜的临床价值

目的探讨儿童过敏性紫癜的影像学特点及其临床价值。方法回顾性分析32例过敏性紫癜并发肠套叠患儿的临床及影像学资料。结果出现并发症之前过敏性紫癜的腹部X线主要表现为局限性小肠充气扩张，粘膜增粗，肠间隙增宽，可伴有液平；B超显示为不同程度的多发节段性肠壁水肿增厚，肠管狭窄等表现；出现并发症后，其X线表现加重，部分病例伴有肠穿孔；B超及X线监视下空气灌肠可以明确是否并发肠套叠，部分病例可通过空气灌肠达到复位治疗的目的。结论影像学检查的重要临床价值在于能与需要手术治疗的其他急腹症相鉴别，同时可以了解其是否并发常见的并发症，为临床确定治疗方案提供可靠的信息。     

Plasma proteins in a standardised skin mini-erosion (II): effects of extraction pressure

Background  

A standardised suction technique has been used to sample plasma proteins in dermal interstitial fluid (IF) serially for 5 to 6 days from a suction-induced skin mini-erosion. Increased protein concentrations ascribed to inflammation have been shown from day 1 onward. In this study, we assessed the effect of two different extraction pressures on IF sample composition.     

二乙基亚硝胺诱导大鼠肝细胞癌过程中明胶酶的动态变化

目的：观察肝癌形成过程中明胶酶表达（蛋白及mRNA水平）的动态变化，探索明胶酶在肝癌生长浸润中的作用。方法：应用免疫组化法、明胶酶谱法和RT-PCR法对大鼠肝癌形成过程中各期明胶酶表达情况进行观察，并与正常对照组进行比较分析。结果：正常肝组织及肝硬化组织内明胶酶有表达，肝癌形成后主要在癌细胞内表达；明胶酶原在正常肝组织中有低表达，诱癌过程中呈持续增高趋势；明胶酶-2mRNA与其酶蛋白表达趋向一致。结论：在肝癌形成过程中明胶酶转录和翻译水平均呈持续增高趋势。     

TRH、EGF及地塞米松促进未成熟胎肺组织分化及表面活性物质合成的研究

目的 比较TRH、EGF与地塞米松对未成熟胎肺形态发育及表面活性物质水平的影响。方法 在兔妊娠第22－24d或第24－26d分别用TRH、EGF或地塞米松母体静脉注射治病，通过光镜、图像分析及电镜等技术观察胎肺的形态结构，并检测胎肺的磷脂水平。结果 光镜下，TRH、EGF与地塞米松治疗组第25d及27d胎肺肺泡腔、肺泡间隔发育均明显好于对照组；EGF、TRH与地塞米松治疗组第27d胎肺的肺泡腔与肺泡间隔的面积比无明显差异。但EGF和TRH治疗组第25d胎肺的肺泡腔与肺泡间隔之比明显小于地塞米松治疗组。电镜下，三个治疗组第27d胎肺内含有板层体的Ⅱ型上皮细胞数量明显多于对照组，但各治疗组及对照组第25d的胎肺Ⅱ型上皮细胞胞浆内几乎未见明显板层体，相反胞浆内糖原含量却非常丰富。此外，三个治疗组27d胎肺的磷脂水平均明显高于对照组。结论 EGF、TRH及地塞米松在兔妊娠第24－26d母体治疗均能促进胎肺的形态发育和表面活性物质的合成，三种治疗方法对胎肺的影响程序无明显不同；在妊娠第22－24d治疗，地塞米松对胎肺形态结构的促进作用较EGF和TRH更明显，但三者对Ⅱ型上皮细胞分化及表面活性物质的合成均无明显影响。     

Therapy of human cervical carcinoma with monoclonal antibody-Pseudomonas exotoxin conjugates.

Pseudomonas exotoxin A (PE) linked to the F(ab')2 fragment of 1H10, a murine monoclonal antibody recognizing a carbohydrate epitope of a glycoconjugate expressed on the surface of human cervical carcinoma tumor cells, was evaluated for in vitro and in vivo activity. PE can kill cells by ADP-ribosylating elongation factor 2 thus inhibiting protein synthesis. Disulfide- as well as thioether-linked immunotoxins (1H10-PE) killed cervical carcinoma cells in vitro and were 20-160 times more inhibitory to target than to control cells. Cell killing was antibody mediated as demonstrated by the reduction of 1H10-PE growth inhibition to target CaSki cells by free 1H10 F(ab')2. In addition, a control antibody immunotoxin was nontoxic to CaSki cells. Thioether-linked 1H10-PE administered either i.v. or i.p. suppressed the growth of established solid s.c. cervical carcinoma tumors xenografted in nude mice for over 30 days. Treatment with antibody alone or a control immunotoxin had no significant effect on tumor growth. Administration of immunotoxin i.p. was associated with less toxicity than administration i.v., but i.v. injections were more effective at suppressing the growth of established solid tumors.     

人肿瘤特异抗原MAGE-3基因疫苗的构建和表达

目的：克隆肿瘤特异性共享抗原mage-3基因，制备基于α－病毒复制酶的高效黑色素瘤特异性基因疫苗。方法：用RT-PCR方法从黑色素瘤细胞系LB373中制备mage-3基因，以含α－病毒复制酶的哺乳细胞高效表达质粒pSMART2a为载体，构建重组DNA疫苗。重组子用载体中的T7和T3启动子序列为测序引物进行自动测序。再将鉴定过的重组质粒用脂质体法转化293细胞，用免疫印迹法和免疫组化法鉴定转化细胞中mage-3蛋白的表达。结果：正确构建了mage-3/pSMART2a重组质粒，并且在转化此质粒的293细胞中检测出了mage-3蛋白的表达。结论：此重组mage-3/pSMART2a质粒可以作为肿瘤特异的DNA疫苗，可进行下一步的肿瘤动物模型的疫苗接种及相关免疫学效应研究。     

后SARS时期对公共卫生与健康的再思考

在人们印象中“公共卫生”是一个很模糊的领域，它比较形象的载体可能就是爱国卫生运动或预防接种。美国1932年提出的公共卫生的定义，对现在依然有指导意义：公共卫生就是预防疾病，延长寿命，通过有组织的社会共同努力来改变环境卫生，从而促进身体的健康，提高工作效率，控制社区传染病的流行，教育个人形成良好的卫生习惯，组织医护人员对疾病进行早期的诊断和预防性治疗。简而言之，“公共卫生”就是关注公众健康的科学。公共卫生学不能脱离临床医学，后是对某种疾病的个体的治疗，而前则着眼对某种疾病做群体防护。     

建立一种新的多药耐药的诱导方法

目的建立裸鼠原位肝癌耐药模型。方法培养肝癌细胞系HepG2,建立裸鼠的皮下肿瘤,形成“供瘤鼠”。开腹直视下将瘤块种植于裸鼠的肝包膜下建立原位肝癌模型,通过表阿霉素间歇腹腔化疗,建立裸鼠原位肝癌耐药模型。用体检、B超、CT、剖腹探查监测肝内瘤块生长情况。用逆转录聚和酶链反应(RT-PCR)和免疫组织化学方法检测肿瘤耐药基因mdrl-mRNA和p-gp蛋白的表达。结果(1)模型建立无手术死亡(0/25),种植成瘤率为88%(22/25),补种3例全部成功,耐药诱导成功率为80%(16/20);(2)诱导组mdrl-mRNA和P-gp蛋白的表达均明显高于对照组,分别约是对照组的23倍和13倍。结论成功地建立了与临床肝癌相似的裸鼠原位肝癌耐药模型,为进一步研究肝癌多药耐药基因的诊断和逆转提供了良好的动物平台。