带有隐含神经元的单层神经网络模型

提出了一种带有隐含神经元的单层神经网络模型。把网络的记忆容量区分为信息记忆容量和物理记忆容量。新模型能记忆相关图样,其信息容量α_i(最大记忆图样数/表达神经元数)首次超过了1。所作出的计算机模拟结果,表明了理论分析的正确性,证实了由5×5个显神经元组成的点阵能记住包含26个英文字母和4个任选图样的30个图样,因此该模型为神经网络的广泛应用提供了一条重要途径。     

大果木姜子的甘油三酯组成

采用光谱法和胰酯酶分解法对大果木姜子油酯中分得的结晶C—I组成进行了分析,结果表明C—I是由11种甘油三酯组成。其中2-位为月硅酸的甘油三酯占91.80％,1,3-位脂肪酸主要为癸酸和月桂酸,甘油三酯的组成中,CLC占62.24％,LLC占24.50％。     

利用带有原核增强子样序列的新型载体在大肠杆菌中高效表达人α肿瘤坏死因子

将去除信号肽的人肿瘤坏死因子-α(Tumor necrosis factor-α,TNF-α)cDNA插入到带有原核增强子样序列Px的新型表达载体pBV320中,使TNF cDNA 5′端直接置于大肠杆菌trp启动子下游,采用37℃恒温培养,使TNF在大肠杆菌中获得了高效表达,表达活性达1.35(±0.17)×10~6U/L菌液。表达的TNF-α对L929细胞的毒性作用可被抗人肿瘤坏死因子-α的单克隆抗体所中和。表达菌裂解液作SDS-聚丙烯酰胺凝胶电泳,显示有一条分子量与TNF分子量吻合、约为17000道尔顿的蛋白带。利用DEAE-Sepharose阴离子交换层析及Sephacryl S-200凝胶过滤对上述重组人TNF-α进行纯化,获得电泳纯产品,比活性为1.48×10~6U/mg。     

Utilization of alpha-ketoglutarate as a precursor for transmitter glutamate in cultured cerebellar granule cells

Alpha-ketoglutarate together with an amino group donor (alanine) was shown to be able to serve as a precursor for the glutamate pool which is released by potassium-induced depolarization (i.e., transmitter glutamate) in cerebellar granule cells. However, these compounds could not be utilized as precursors for intracellular glutamate or for release of transmitter aspartate. The formation of transmitter glutamate was inhibited by the transamination inhibitor aminooxyacetic acid but not by phenylsuccinate, an inhibitor of the dicarboxylate carrier in the mitochondrial membrane. Both of these inhibitors have previously been found to inhibit synthesis of transmitter glutamate from glutamine. The results support the hypothesis that alpha-ketoglutarate and alanine undergo transamination in the cytosol to form pyruvate and glutamate, and that this glutamate pool is available for transmitter release of glutamate but does not constitute the major intracellular pool of glutamate.     

Alpha-2-adrenergic modulation of the parathyroid hormone-inhibition of phosphate uptake in cultured renal (OK) cells

Parathyroid hormone enhances the formation of cAMP and decreases the Na+-dependent uptake of phosphate in cultured renal cells derived from the American opossum (OK cells). Epinephrine, acting as an alpha 2-adrenergic agonist, inhibits the PTH-induced synthesis of cAMP by a pertussis toxin-sensitive mechanism and blunts the inhibition of phosphate transport by PTH. Na+-dependent alpha-methylglucoside and Na+ uptakes by the cells are unaffected by PTH and epinephrine. These findings suggest that alpha 2-adrenergic agonists may selectively modulate PTH-sensitive phosphate transport in the renal proximal tubule.     

Computer aided analysis for biosensing and screening

Biosensors with animal and microbial cells immobilized close to the tip of a membrane electrode have been developed for chemical and drug testing. Our experimental results show that biosensors can be used for drug screening and to provide useful information about various cell-chemical interactions. A computer aided analysis (CAA) software package is being developed here using the biosensor for various screening purposes. This software package enables us to use a computer to analyze the biosensor dynamic responses. Computer simulation and parameter estimation techniques are used to select the best model and to describe the biochemical and pharmacologic effects of various chemicals and drugs on different cell lines.     

To early distinguish neonatal transient leukemoid proliferation from congenital leukemia by in vitro cell growth

To differentiate neonatal transient leukemoid proliferation from congenital leukemia at an early stage is often difficult. Bone marrow culture is found to be helpful in this aspect. A normal in vitro growth pattern suggests transient leukemoid proliferation, while an abnormal growth pattern indicates congenital leukemia. A neonate who manifested with pictures mimicking acute myeloblastic leukemia (M1), had a karyotype of 46, XY/46, XY, i(21 q). However, the in vitro growth pattern was normal and so only supportive treatment was given. All the leukemoid manifestations disappeared several months later and he is now a healthy 2 year old boy remaining in complete remission. A second neonate who also displayed features of acute myeloblastic leukemia (M2), had a karyotype of 46, XY/47, XY, + 21 and abnormal in vitro growth pattern. This neonate died at 18 days of age.