High-proportion differentiation of neural stem cells into neurons and formation of neural networks induced by active biomaterial scaffolds in vitro / 中国组织工程研究

BACKGROUND: Either good biocompatibility and biological activity of active biological materials or the potential of multidirectional differentiation of neural stem cells has great application prospect and value. OBJECTIVE: To investigate the effect of neurotrophic factor 3-chitosan active biomaterial scaffolds on the differentiation of neural stem cells and the expression of key proteins of the neurotrophic factor 3 signal pathway in vitro. METHODS: The neural stem cells were extracted and purified, and then divided into pure culture medium group, soluble neurotrophic factor 3 group, pure chitosan group, and neurotrophic factor 3-chitosan group for differentiation induction. The expression of TrkC, Akt / p-Akt and Erk/p-Erk in the neurotrophic factor 3 signaling pathway was detected by western blot after 6 hours of induction. After 7 days of induction, differentiation of neural stem cells was observed by immunocytochemistry of MAP2, MBP, and GFAP. After 14 days of induction, formation of neural network induced by neurotrophic factor 3-chitosan active biomaterials was observed by immunocytochemistry of MAP2, Synapsin-1, and PSD95. RESULTS AND CONCLUSION: The neurotrophic factor 3-chitosan group induced a high proportion of neural stem cells differentiated into neurons, with a ratio of 73.8%, which was significantly higher than that in the other three groups. Meanwhile, the proportion of cells differentiated into glial cells waslower than that in the other three groups. The expression of key proteins TrkC, p-Akt and p-Erk in the neurotrophic factor 3-chitosan group was higher than that in the other three groups. Meanwhile, neurotrophic factor 3-chitosan could induce the in vitro differentiation of neural stem cells to form neural network.

Electrophysiological characteristics of hippocampal postnatal early development mediated by AMPA receptors in rats / 生理学报

The present study was aimed to investigate the electrophysiological characteristics of hippocampal postnatal early development mediated by α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors in rats. Forty-eight Wistar rats were divided into postnatal 0.5-, 1-, 2- and 3-month groups (n = 12). Spontaneous excitatory postsynaptic currents (sEPSCs) and field excitatory postsynaptic potentials (fEPSPs) mediated by AMPA receptors were recorded to evaluate the changes in the intrinsic membrane properties of hippocampal CA1 pyramidal neurons by using patch-clamp and MED64 planar microelectrode array technique respectively. The results showed that, during the period of postnatal 0.5-3 months, some of the intrinsic membrane properties of hippocampal CA1 pyramidal neurons, such as the membrane capacitance (Cm) and the resting membrane potential (RMP), showed no significant changes, while the membrane input resistance (Rin) and the time constant (τ) of the cells were decreased significantly. The amplitude, frequency and kinetics (both rise and decay times) of sEPSCs were significantly increased during the period of postnatal 0.5-1 month, but they were all decreased during the period of postnatal 1-3 months. In addition, the range of evoked fEPSPs in hippocamal CA1 region was significantly expanded, but the fEPSP amplitudes were decreased significantly during the period of postnatal 0.5-3 months. Furthermore, the evoked fEPSPs could be significantly inhibited by extracellular application of the AMPA receptor antagonist 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX). These results suggest that AMPA receptor may act as a major type of excitatory receptor to regulate synaptic transmission and connections during the early stage of hippocampal postnatal development, which promotes the development and functional maturation of hippocampus in rats.

Functional expression of congenital long QT syndrome related HERG mutation A561V in vitro / 中华心血管病杂志

<p><b>OBJECTIVE</b>To investigate the functional expression of HERG mutation A561V detected in a Chinese congenital long QT syndrome family.</p><p><b>METHODS</b>The mutation gene A561V was cloned into eukaryotic expressive vector pcDNA3 by quick site-directed mutagenesis PCR and restriction enzymes. The wild-type HERG, heterozygous type HERG and HERG mutation A561V were respectively cotransfected with pRK5-GFP into HEK293 cells by Suprefact transfection regent. The protein expression was measured by immunofluorescence method and Western blot. The electrophysiological characteristics of transfected cells were determined by whole cell patch-clamp technique.</p><p><b>RESULTS</b>Direct sequence analyses revealed a C to T transition at position 1682. A561V mutation was correctly combined to eukaryotic expressive vector pcDNA3 and expressed in HEK293 cells. The protein expression of mutation and heterozygosis were located in cytoplasm and cellular membrane. 155 kDa and 135 kDa protein bands were detected in wild type HERG channel while only 135 kDa protein band was shown in heterozygous and mutational channels. Significant HERG tail-current was recorded in wild type HERG channel but not in mutation and heterozygosis channels.</p><p><b>CONCLUSION</b>This study evidenced a functional dominant-negative current suppression in HEK293 cells transfected with HERG mutation A561V.</p>

Single nucleotide polymorphisms of genes associated with high density lipoprotein metabolism in Chinese population / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To study the single nucleotide polymorphisms in genes associated with the high density lipoprotein (HDL) metabolism in Chinese population.</p><p><b>METHODS</b>Two hundred and nine normal Han ethnic subjects, aged 59+/-10 years, were recruited from 5 medical centers in western part of China. DNA was extracted by proteinase K digestion, phenol and chloroform extraction as well as isopropanol precipitation. The polymerase chain reaction (PCR)-restriction fragment length polymorphisms (RFLP) in conjunction with sequencing were employed to test the single nucleotide polymorphisms (SNPs) in ATP-binding cassette transporter (ABCA1), cholesteryl ester transfer protein (CETP) and lipoprotein lipase (LPL) genes.</p><p><b>RESULTS</b>The allelic frequencies of A and G of ABCA1 gene are 53.4% and 46.6%; of B2 and B1 allele of CETP, 41.0% and 59.0%; of HindIII (-) and (+) allele of LPL, 18.9% and 81.1%; and of PvuII(+) and (-) allele of LPL, 66.0% and 34.0%, respectively. All genotype frequencies fit well with the Hardy-Weinberg equilibrium; the significant linkage disequilibrium exists between LPL HindIII(+)and PvuII(+) polymorphisms. All of the RFLP in these genes result from the single nucleic substitution in fragment recognized by corresponding restriction enzymes.</p><p><b>CONCLUSION</b>The genetic polymorphisms of ABCA1, LPL-HindIII and LPL-PvuII in Chinese Han ethnic population are significantly different from Caucasians residing in USA or Europe.</p>

Methylation status of promoter of mismatch repair genes hMLH1 and hMSH2 in epithelial ovarian cancer / 中华检验医学杂志

Objective To explore the methylation status of hMLH1 and hMSH2 promoter region in the epithelial ovarian cancer and its role in oncogenesis.Methods Methylation status of hMLH1 and hMSH2 promoter region was assayed in 20 normal ovarian tissues,25 benign epithelial tumor,56 malignant epithelial tumor and cell lines SKOV3,3AO by methylation-specific PCR (MSP).SKOV3 and 3AO were analyzed before and after 5-aza-2′-deoxycytidine (5-Aza-CdR) treatment.In addition,an alterations of mRNA expression of hMLH1 and hMSH2 was observed by reverse transcription polymerase chain reaction (PT-PCR).Results No methylation of hMLH1 and hMSH2 promoter was found in normal ovarian tissues. CPG islands methylation of hMLH1 and hMSH2 was observed in 4% (1/25),8% (2/25) respectively in benign epithelial tumor,30.4% (17/56),51.8% (29/56) respectively in malignant epithelial tumor. Methylation status in promoter showed obvious correlation with pathological grade and lymph node metastasis (P