Functional synapses are formed between human NTera2 (NT2N, hNT) neurons grown on astrocytes

The formation of functional synapses is a late milestone of neuronal differentiation. The establishment of functional synapses can be used to assess neuronal characteristics of different cell lines. In the present study, we examined the in vitro conditions that influence the ability of human neurons derived from the NT2 cell line (NT2N neurons) to establish synapses. The morphologic, immunologic, and electrophysiologic characteristics of these synapses was examined. In the absence of astrocytes, NT2N neurons rarely formed synapses and their action potentials were weak and uncommon. In contrast, when plated on primary astrocytes, NT2N neurons were able to form both glutamatergic excitatory (71%) and GABAergic inhibitory (29%) functional synapses whose properties (kinetics, ion selectivity, pharmacology, and ultrastructure) were similar to those of synapses of neurons in primary cultures. In addition, coculture of NT2N neurons with astrocytes modified the morphology of the neurons and extended their in vitro viability to more than 1 year. Because astrocyte-conditioned medium did not produce these effects, we infer that direct contact between NT2N neurons and astrocytes is required. These results suggest that NT2N neurons are similar to primary neurons in their synaptogenesis and their requirement for glial support for optimal survival and maturation. This system provides a model for further investigations into the neurobiology of synapses formed by human neurons.     

α1-抗糜蛋白酶基因、早老素1基因 与阿尔茨海默病的相关分析

目的探讨中国汉族人中α１抗糜蛋白酶（ＡＡＣＴ）基因、早老素１（ＰＳ１）基因多态性与阿尔茨海默病（Ａｌｚｈｅｉｍｅｒｓｄｉｓｅａｓｅ,ＡＤ）的相关情况。方法应用ＰＣＲＲＦＬＰ方法,在１２３例患者和１４０例正常人中观察ＡＡＣＴ信号肽和ＰＳ１基因多态性的分布,进行关联分析。结果１ＡＤ患者与ＰＳ１基因等位基因１正关联,与等位基因２和基因型２／２负关联,但与１／１基因型无关;２ＡＡＣＴ信号肽基因多态性与ＡＤ无关联;３在三种ＰＳ１基因型中,ＡＡＣＴ信号肽基因多态性与ＡＤ均无关;４在ＡＡＣＴ基因ＡＡ、ＴＴ基因型中,ＰＳ１基因多态性与ＡＤ负关联,而ＴＡ型中ＰＳ１基因与ＡＤ无显著相关。结论中国人群中,ＡＤ与ＰＳ１基因２／２型负关联,而与ＡＡＣＴ信号肽基因多态性无关;ＡＡＣＴ信号肽和ＰＳ１基因多态性之间也无明显的相互影响。     

Liver resection for hepatocellular carcinoma in octogenarians

BACKGROUND: Liver resection is risky in patients aged > or = 80 years. Because of short life expectancies and improved nonoperative modalities, the role of liver resection in octogenarians with hepatocellular carcinoma (HCC) is unclear. METHODS: A retrospective review of the operative results of 260 patients with HCC between 1991 and 1997 was performed. According to the age at the time of operation, these patients were divided into 2 groups. Group 1 comprised 21 patients aged > or = 80 years, and group 2 comprised the other 239 younger patients. The backgrounds, pathologic features of the tumor, and operative results of the patients were compared. RESULTS: Octogenarians had a higher incidence of associated medical diseases, a higher incidence of negative serum hepatitis B surface antigen, a lower alpha-fetoprotein level, and a higher indocyanine green retention rate. Although octogenarians had a longer postoperative hospital stay, there were no significant differences between the 2 groups regarding operative morbidity and mortality. The 5-year disease-free and actuarial survival rates for octogenarians and younger patients were 50.6% and 35.3% (P = .15) and 40.9% and 59.3% (P = .46), respectively. CONCLUSION: Under meticulous preoperative assessments and postoperative care, liver resection for HCC is justified in selected octogenarians, with short- and long-term results comparable to those of younger patients.     

The experience in the treatment of patients with extensive full-thickness burns

The aim of the present study is to analyze the changes of cure rate and the main causes of death in the last 40 years, and to summarize our experience in the treatment of extensive full-thickness burn patients. The clinical characteristics, cure rate and main causes of death of 73 cases with total burned area more than 90% TBSA and full-thickness burn area more than 70% TBSA were analyzed retrospectively. Among them, 21 cases (28.8%) were cured and 52 cases (71.2%) died. The cure rate increased significantly in the recent years, and the main causes of death changed from shock and sepsis in the time period 1959–1978 to sepsis and MODS in the past two decades. Due to the improvement of early comprehensive management of burn shock, aggressive surgical approach to full-thickness burn wound and potent systemic supporting measures, the survival rate increased significantly.     

The effect of burn subeschar tissue fluid on skeletal muscle and hepatic amino acid uptake in an experimental system in vitro

Burn injury is associated with major metabolic disturbances. Many factors or mediators are responsible for post-burn metabolic changes. The present study was designed to test the role of interstitial edema fluid from burn eschar in regulating amino acid transport into hepatic and muscle tissue. Subeschar tissue fluid (SEF) was collected from just under the full thickness burn area. Amino acid transport, determined as the uptake of [3H]-alpha-aminoisobutyric acid by incubated soleus muscles or liver slices in vitro, was reduced after the addition of subeschar tissue fluid. The suppression was more marked with fluids taken from patients with a large burn area. Significant findings were noted when the total surface burn area was more than 70%. There were significant differences in the SEF suppression effect between survivors and non-survivors, but not between inhalation and non-inhalation victims. The results suggest the presence of one or more factors in subeschar tissue fluid that inhibit both muscle and liver amino acid transport. The data also suggest that the inhibitory factors are most likely produced by the burned tissue. This suppression effect may be beneficial to burn victims in maintaining near-normal vascular osmolarity by way of an increased plasma amino acid level.     

术后患者肠道吸收乳果糖、甘露醇的变化与创伤程度的关系

目的 测定手术后患者肠道对甘露醇和乳果糖吸收的变化,并研究这些变化与手术应激程度的关系。方法 用小剂量乳果糖（ｌａｃｔｕｌｏｓｅ,Ｌ,２ｇ）和甘露醇（ｍａｎｎｉｔｏｌ,Ｍ,１ｇ）的方法测定２０例腹部手术患者术前,术后第５第和１０天乳果糖／甘露醇比值（Ｌ／Ｍ比值）的变化。用急性生理和慢性健康状况评分方法Ⅱ（ＡＰＡＣＨＥⅡ）对患者的创伤程度进行评分。用带电化学检测器的高压液相色谱仪测定尿中的乳果糖和甘     

具有一般截面形状的平面复合曲梁正应力分析

分析工程中对于由多种材料组合而成的一般截面形状平面曲梁在载荷作用下的强度问题.在截面形状不变的假设基础上,导出了其正应力的计算公式.作为特殊情况,该梁在对称弯曲时的相应公式也可以从上述公式得到,最后给出了计算实例.     

4个铁路区段提速列车噪声影响调查

为探讨提速列车噪声对铁路两侧环境及居民健康影响,依据声源,环境噪声等固定标准,对４个铁路运行区段进行了调查。     

Factors limiting contrast sensitivity in experimentally amblyopic macaque monkeys

Contrast detection is impaired in amblyopes. To understand the contrast processing deficit in amblyopia, we studied the effects of masking noise on contrast threshold in amblyopic macaque monkeys. Amblyopia developed as a result of either experimentally induced strabismus or anisometropia. We used random spatiotemporal broadband noise of varying contrast power to mask the detection of sinusoidal grating patches. We compared masking in the amblyopic and non-amblyopic eyes. From the masking functions, we calculated equivalent noise contrast (the noise power at which detection threshold was elevated by square root of 2) and signal-to-noise ratio (the ratio of threshold contrast to noise contrast at high noise power). The relation between contrast threshold and masking noise level was similar for amblyopic and non-amblyopic eyes. Although in most cases there was some elevation in equivalent noise for amblyopic compared to fellow eyes, signal-to-noise ratio showed greater variation with the extent of amblyopia. These results support the idea that the contrast detection deficit in amblyopia is a cortical deficit.