Biomedical subjects

Yong Liu

Publications and source records attributed to Yong Liu.

At least 217 records · Page 12Linked to original sources

PubMed2003

[Studies on the chemical constituents from the aerial parts of Cimicifuga dahurica].

AIM: To seek for new bioactive constituents from the aerial parts of Cimicifuga dahurica. METHODS: Various column chromatographic techniques were employed for the isolation and purification of the ingredients. The structures were elucidated on the basis of 1H, 13CNMR, 1H-1H COSY, HMQC, NOESY and HMBC spectra and chemical reactions. RESULTS: Two cyclolanostanol xylosides, cimidahuside C and D were isolated from the EtOAc section of EtOH extracts. CONCLUSION: Cimidahuside C(1) and D(2) are new triterpenoid xylosides.

Cimicifuga↗

PubMed2003

[Expression of amino terminal of nucleoprotein and glycoprotein G2 of Hantaan virus in insect cells in the form of fusion protein].

AIM: To express the glycoprotein G2 and amino terminal of nucleoprotein (NP) of Hantaan virus in Bac-to-Bac baculovirus expression system in the form of fusion protein. METHODS: The recombinant baculovirus expression vector pFBDHTa-G2S 0.7 was constructed. The chimeric gene was inserted into bacmid in E.coli DH10Bac with the help of Tn7 transposition system. Then the recombinant baculovirus was screened and the fusion protein was expressed in insect cells. The expression product was detected by ELISA, immunofluorescence assay and Western blot analysis. RESULTS: The recombinant baculovirus containing the chimeric gene G2S 0.7 had been constructed successfully and the fusion protein could be expressed in insect cells. The expressed protein could be recognized by the Hantaan virus NP-specific mAb and glycoprotein G2-specific mAb. CONCLUSION: The successful expression of fusion protein G2S 0.7 with biological activity in insect cells lays the foundation for further research on its immunological characteristic.

Animals↗

PubMed2003

[Construction and identification of recombinant retrovirus vector containg hTrx gene].

AIM: To construct a recombinant retrovirus vector carrying hTrx gene. METHODS: hTrx gene was cloned directionally into a retroviral vector pLXSN by DNA recombinant technique and the recombinant vector was identified EcoRI and BamHI digestion analysis. The recombinant was transfected into packaging cells PA317 via CaPO(4)-based transfection method, and viral titer in culture supernatant of transfected cells was detected. RESULTS: The recombinant pLTrxSN had been constracted. EcoRI and BamHI digestion analysis displayed two positive bands of 0.3 kb and 5.9 kb respectively. The viral titer in supernatant of transfected cells was 5.5x10(9) cfu/L. CONCLUSION: pLhTrxSN has been constructed successfully, which will be useful for Trx gene therapy and experiment study.

Genetic Therapy↗

PubMed2003

[How to search for foreign website on plant biology].

Plant growth and development, plant cell signaling and gene regulation, plant genome research were the hotpoint of current plant biology research. We introduce the mainly foreign website concerning with the three fields, and hope it will be helpful for the plant biology researchers.

English Abstract↗

PubMed2002

Detection of p16 hypermethylation in circulating plasma DNA of non-small cell lung cancer patients.

We detected tumor-associated aberrant hypermethylation of the p16 gene in plasma DNA from 105 non-small cell lung cancer (NSCLC) patients (65 squamous cell carcinoma (SCC) and 40 adenocarcinoma (ADC)) and 92 matched tumor DNA samples, using a modified semi-nested methylation-specific PCR (MSP). This technique increased the sensibility of detecting p16 hypermethylation from DNA samples in varying stages. p16 hypermethylation was present in 73.3% (77/105) of the plasma samples, and 79.3% (73/92) of the tumor samples. Among those cases with methylated p16 sequence in tumor samples, 87.7% (64/73) also demonstrated this epigenetic alteration in the corresponding plasma DNA. Only patients whose tumor cells had hypermethylated p16 gene exhibited aberrant methylation in their plasma samples. Regarding different clinical stages of SCC and ADC, the frequencies of p16 hypermethylation in plasma DNA were nearly the same as those in corresponding tumors, except for stage I ADC. Our study indicated that aberrant methylation of p16 may be an excellent biomarker for early diagnosis and follow-up of NSCLC patients, and MSP is a reliable method for these purposes.

Carcinoma, Non-Small-Cell Lung↗

PubMed2002

Activation of NMDA receptors and L-type voltage-gated calcium channels mediates enhanced formation of Fyn-PSD95-NR2A complex after transient brain ischemia.

Recent studies have indicated that tyrosine phosphorylation of NMDA receptor subunit 2A (NR2A) by Src family kinases (Src, Fyn, etc.) up-regulates NMDA receptors activity and postsynaptic density protein 95 kDa (PSD95) may mediate the regulation. To investigate whether the above processes are involved in brain ischemia-induced enhancement of NMDA receptors function, we examined the effects of transient (15 min) brain ischemia followed by reperfusion on interactions involving Fyn, NR2A and PSD95 in rat hippocampus by co-immunoprecipitation. Transient brain ischemia was induced by the method of four-vessel occlusion in Sprague-Dawley rats. Association between Fyn and NR2A increased immediately after brain ischemia and the increase was maintained for at least 24 h during followed reperfusion, up to about 1.7-1.8-fold relative to sham-groups. The 15-min reperfusion after brain ischemia induced enhanced co-immunoprecipitation of PSD95, Fyn and NR2A with one another. The associations of PSD95 with Fyn and NR2A increased at 0-24 h, 0-1 h of reperfusion, up to 6.9- and 2.1-fold relative to sham groups, respectively. Inhibiting activation of NMDA receptors or L-type voltage-gated calcium channels (L-VGCC) by ketamine or nifedipine attenuated the above increases of associations. These results suggest that stimulation of NMDA receptors and L-VGCC facilitates formation of a ternary complex: Fyn-PSD95-NR2A during transient brain ischemia followed by reperfusion, which may result in potentiation of NMDA receptor function and contribute to ischemic neuronal cell death.

Animals↗

PubMed2002

Deletion of tumor suppressor genes in Chinese non-small cell lung cancer.

In the present study, we used 22 microsatellite markers flanking to or within 13 known or candidate tumor suppressor genes (TSGs) to detect loss of heterozygosity (LOH) in these chromosomal regions among 41 cases of non-small cell lung cancer, including 28 squamous cell carcinoma (SCC) and 13 adenocarcinoma (ADC). The studied TSGs comprised FHIT, VHL, APC, PRLTS, p16, IFNA, PTEN, p57, ATM, p53, BRCA1, DPC4 and DCC. Our data demonstrated frequent allelic losses of FHIT, p53, IFNA, VHL and p16 in both SCC and ADC. PTEN and ATM showed the least frequency of LOH, while no deletion of BRCA1 was detected in all tumor samples. LOH analysis of PRLTS was extended to 26 cases of ADC, which demonstrated significantly higher frequency of LOH than SCC. Our data indicated a possible correlation between specific TSG(s) and either histological type of lung cancer, and more attention should be paid to the PRLTS gene, which might play an important role in the development of ADC.

Adenocarcinoma↗

PubMed2002

Chromosomal aberrations, DNA strand breaks and gene mutations in nasopharyngeal cancer patients undergoing radiation therapy.

Nasopharyngeal cancer (NPC) is a common disease in the south part of China, and its incidence is increasing in the southwest of China in recent years. Radiation therapy is the main therapeutic method for NPC in China. In this study, genetic changes were assessed in randomly selected nine NPC patients receiving radiation therapy by different genotoxical screening methods, the cytokinesis-block micronucleus test (CB-MNT), the buccal mucosa cell micronucleus test (BMC-MNT), the undivided lymphocyte micronucleus test (UL-MNT), chromosomal aberration (CA) test, the comet assay and the hprt gene mutation test (HPRT). Patients were used as self-control before receiving radiation therapy. Apart from the UL-MNT, all the methods detected genetic damages in NPC patients, though with different sensitivities. CB-MNT is the best biological indicator for evaluating genetic damage induced by radiation therapy in NPC patients; followed by CA and HPRT, while the BMC-MNT is simplest method as a potential biological indicator.

Adult↗

PubMed2002

Identification of gene function and functional pathways by systemic plasmid-based ribozyme targeting in adult mice.

To date, functional genomic studies have been confined to either cell-based assays or germline mutations, using transgenic or knockout animals. However, these approaches are often unable either to recapitulate complex biologic phenotypes, such as tumor metastasis, or to identify the specific genes and functional pathways that produce serious diseases in adult animals. Although the transcription factor NF-kappaB transactivates many metastasis-related genes in cells, the precise genes and functional-pathways through which NF-kappaB regulates metastasis in tumor-bearing hosts are poorly understood. Here, we show that the systemic delivery of plasmid-based ribozymes targeting NF-kappaB in adult, tumor-bearing mice suppressed NF-kappaB expression in metastatic melanoma cells, as well as in normal cell types, and significantly reduced metastatic spread. Plasmid-based ribozymes suppressed target-gene expression with sequence specificity not achievable by using synthetic oligonucleotide-based approaches. NF-kappaB seemed to regulate tumor metastasis through invasion-related, rather than angiogenesis-, cell-cycle- or apoptosis-related pathways in tumor-bearing mice. Furthermore, ribozymes targeting either of the NF-kappaB-regulated genes, integrin beta(3) or PECAM-1 (a ligand-receptor pair linked to cell adhesion), reduced tumor metastasis at a level comparable to NF-kappaB. These studies demonstrate the utility of gene targeting by means of systemic, plasmid-based ribozymes to dissect out the functional genomics of complex biologic phenotypes, including tumor metastasis.

Aging↗

PubMed2002

Chemokine production by rat alveolar macrophages is inhibited by taurine chloramine.

Taurine protects lung tissue from oxidant-induced damage in a variety of models that involve inflammation as a pathogenic feature. The mechanism of taurine protection is thought to be related to the formation and subsequent action of taurine chloramine (Tau-Cl). Tau-Cl results from the activity of a halide-dependent myeloperoxidase system associated with neutrophils. Since chemokines are secreted by activated alveolar macrophages and are prominently involved in propagating the inflammatory response in lung, we determined the effects of Tau-Cl on MCP-1 and MIP-2 production in NR8383, a cloned cell line derived from rat alveolar macrophages. Activation of NR8383 cells with LPS and IFN-gamma resulted in accumulation of MCP-1 and MIP-2 in the conditioned media over the following 24-h and this was inhibited by Tau-Cl in a concentration dependent fashion. Northern blot analyses of MCP-1 and MIP-2 mRNA expression revealed concentration dependent inhibition by Tau-Cl. Expression of MCP-1 transcripts was more potently inhibited by Tau-Cl relative to that of MIP-2. Since the promoter regions of these chemokine genes are regulated by NF-kappaB, nuclear protein extracts were evaluated for NF-kappaB binding to its sequence specific recognition site (EMSA). Tau-Cl treated cells expressed reduced nuclear NF-kappaB binding relative to the activated control cells. The composition of the NF-kappaB dimer contained predominately p50 and p65 subunits, but some c-Rel was also present. These results suggest that Tau-Cl inhibits production of chemokines by activated NR8383 cells through a mechanism that involves, in part, the NF-kappaB signaling pathway.

Animals↗

PubMed2002

Efficient generation of cytotoxic T lymphocytes against cervical cancer cells by adeno-associated virus/human papillomavirus type 16 E7 antigen gene transduction into dendritic cells.

Adeno-associated virus (AAV) is able to efficiently deliver a cytokine gene into dendritic cells (DC). Improvements in T cell priming by DC might be effected by the delivery of antigen genes into DC, resulting in continuous protein expression, as most proteins have short half-lives. In this study, a recombinant AAV vector containing the human papillomavirus (HPV)-16 E7 gene was used to pulse/infect DC and compared to the pulsing of DC by the lipofection of bacterially produced E7 protein. Pulsing of DC with AAV/antigen (Ag) gene was found to be superior to pulsing with protein in six different assay systems: (1) the level of antigen transfer into DC as determined by intracellular staining; (2) the level of MHC class I-restricted killing in cytotoxic T lymphocyte (CTL) assays; (3) the level of IFN-gamma expression; (4) the level of DC-T cell priming clusters generated; (5) the level of CD80 and CD83 expression on DC; and (6) in the resulting CD8:CD4 ratio. Finally, AAV/Ag gene pulsing resulted in strong CTL activity after only 7 days of priming. These data suggest that AAV vectors may offer advantages over the commonly used protein-pulsing technique and that AAV vectors may be useful for the stimulation of CTL activity and adoptive immunotherapy protocols.

Antigens↗

PubMed2002

Expression of transforming growth factor beta 1 in mesenchymal stem cells: potential utility in molecular tissue engineering for osteochondral repair.

The feasibility of using gene therapy to treat full-thickness articular cartilage defects was investigated with respect to the transfection and expression of exogenous transforming growth factor (TGF)-beta 1 genes in bone marrow-derived mesenchymal stem cells (MSCs) in vitro. The full-length rat TGF-beta 1 cDNA was transfected to MSCs mediated by lipofectamine and then selected with G418, a synthetic neomycin analog. The transient and stable expression of TGF-beta 1 by MSCs was detected by using immunohistochemical staining. The lipofectamine-mediated gene therapy efficiently transfected MSCs in vitro with the TGF-beta 1 gene causing a marked up-regulation in TGF-beta 1 expression as compared with the vector-transfected control groups, and the increased expression persisted for at least 4 weeks after selected with G418. It was suggested that bone marrow-derived MSCs were susceptible to in vitro lipofectamine mediated TGF-beta 1 gene transfer and that transgene expression persisted for at least 4 weeks. Having successfully combined the existing techniques of tissue engineering with the novel possibilities offered by modern gene transfer technology, an innovative concept, i.e. molecular tissue engineering, are put forward for the first time. As a new branch of tissue engineering, it represents both a new area and an important trend in research. Using this technique, we have a new powerful tool with which: (1) to modify the functional biology of articular tissue repair along defined pathways of growth and differentiation and (2) to affect a better repair of full-thickness articular cartilage defects that occur as a result of injury and osteoarthritis.

Animals↗

PubMed2002

Study of rat osteoblasts transfected by transforming growth factor beta 1 gene.

In order to investigate the effect of TGF beta 1 gene transfer on the biological characteristics, the effects of gene transfer and supernatant of transfected osteoblasts on the proliferation and ALP activity of osteoblasts were detected by 3H-TdR and MTT. Our results showed that TGF beta 1 gene transfer had no effect on the biological characteristics and the activated supernatant of transfected osteoblasts stimulated proliferation and inhibited ALP activity of osteoblasts. TGF beta 1 gene transfer could promote the expression of TGF beta 1 and the biological characteristics of transfected osteoblasts were stable, which might be helpful for gene therapy of bone defects in vivo.

Animals↗

PubMed2002

Transfection of articular chondrocytes with rhBMP7 gene and its expression.

In order to investigate the possibility of expression of exogenous gene in transduced articular chondrocytes, plasmid pcDNA3-rhBMP7 was delivered to cultured chondrocytes. Through immunohistochemical staining and RT-PCR assay, the expression of rhBMP7 gene was detected. And the bioactivity of transgene expression product was detected through MTT assay as well. It was confirmed that exogenous gene could be expressed efficiently in transduced chondrocytes and the transgene expression product had obvious bioactivity. The present study provided a theoretical basis for gene therapy on the problems of articular cartilage.

Animals↗

PubMed2002

Two new cyclolanostanol xylosides from the aerial parts of Cimicifuga dahurica.

From the aerial parts of Cimicifuga dahurica, two new cyclolanostanol xylosides, cimilactone A (1) and cimilactone B (2), and three known compounds were isolated. On the basis of spectral and chemical evidence, the structures of 1 and 2 were determined to be 12beta-acetoxy-3beta-O-D-xylopyranosyloxy-24,25,26,27-tetranor-9,19-cyclolanost-16,23-lactone (1) and 12beta-acetoxy-3beta-O-D-xylopyranosyloxy-24,25,26,27-tetranor-9,19-cyclolanost-7-ene-16,23-lactone (2). The known compounds were identified as cimigenol 3-O-beta-D-xylopyranoside, 23-O-acetylshengmanol-3-O-beta-D-xylopyranoside, and 25-O-acetylcimigenol-3-O-beta-D-xylopyranoside, respectively.

Cimicifuga↗

PubMed2002

The effects of the total saponin of Dipsacus asperoides on the damage of cultured neurons induced by beta-amyloid protein 25-35.

According to the pathogenesis of Alzheimer's disease (AD), beta-amyloid protein (A beta) was directly toxic to neurons, leading to neurodegeneration. Total saponin of Dipsacus asperoides (tSDA) is one of the main ingredients of Dipsacus asperoide, a traditional Chinese medicine. To explore the effects of tSDA on neuronal damage induced by A beta in vitro, biochemical analysis combining primary cultured neurons were adopted. Neurons were treated with 35 mmol/L A beta for 24 h, and tSDA at concentrations of 1-300 mg/L were added to A beta-treated cultures 24 h in advance, A beta for 24 h, the survival rate of neurons decreased closely by 50%. Lactate dehydrogenase release and the Malondialdehyde (MDA) level increased substantially. However, if neurons were pretreated with tSDA, the survival rate of neurons was higher than A beta-treated alone. Lactate dehydrogenase release and the MDA level decreased distinctly. Results demonstrated that tSDA possessed a neuroprotective action and that tSDA protected neurons against the toxicity of A beta, most likely by relieving oxidative stress or inhibiting the process of A beta, inducing free radical generation.

Alzheimer Disease↗

PubMed2002

An endogenous RNA transcript antisense to CNG(alpha)1 cation channel mRNA.

CNG channels are cyclic nucleotide-gated Ca(2+)-permeable channels that are suggested to be involved in the activity-dependent alterations of synaptic strength that are thought to underlie information storage in the CNS. In this study, we isolated an endogenous RNA transcript antisense to CNG(alpha)1 mRNA. This transcript was capable of down-regulating the expression of sense CNG(alpha)1 in the Xenopus oocyte expression system. RT-PCR, Northern blot, and in situ hybridization analyses showed that the transcript was coexpressed with CNG(alpha)1 mRNA in many regions of human brain, notably in those regions that were involved in long-term potentiation and long-term depression, such as hippocampal CA1 and CA3, dentate gyrus, and cerebellar Purkinje layer. Comparison of expression patterns between adult and fetal cerebral cortex revealed that there were concurrent developmental changes in the expression levels of anti-CNG1 and CNG(alpha)1. Treatment of human glioma cell T98 with thyroid hormone T(3) caused a significant increase in anti-CNG1 expression and a parallel decrease in sense CNG(alpha)1 expression. These data suggest that the suppression of CNG(alpha)1 expression by anti-CNG1 may play an important role in neuronal functions, especially in synaptic plasticity and cortical development. Endogenous antisense RNA-mediated regulation may represent a new mechanism through which the activity of ion channels can be regulated in the human CNS.

Adult↗

PubMed2002

Recurrent genomic aberrations in gastric carcinomas associated with Helicobacter pylori and Epstein-Barr virus.

Helicobacter pylori and Epstein-Barr virus (EBV) both have been associated with gastric carcinoma. No specific genomic aberrations have been reported in association with these agents. We studied 20 cases of primary gastric carcinoma (including 11 positive for and 6 for EBV) by comparative genomic hybridization with validation of results by fluorescence in situ hybridization, loss of heterozygosity analysis, and immunohistochemistry. The results were analyzed in respect to presence or absence of and EBV. The tumors were also compared in terms of histologic type, tumor location, and lymph node metastases. The most frequently observed aberrations in the gastric carcinomas were gains of chromosome 19, 17, 1p, 11, 20q, and 22. The more common losses were found in 4q, 6q, 13q, and 15q. Gains in chromosome 19 and losses in 9p23-pter were found more commonly in cases with (P < 0.05). Gains in centromeric region of chromosome 19 were more common in the EBV-negative cases (P < 0.05). Immunohistochemical expression of and correlated with gains in the regions containing these genes. Gains in chromosome 11 and losses in 15q15 were more common in cases with EBV (P < 0.01 and P < 0.001, respectively). There was no significant association between any genomic aberration and histologic type, tumor location, or nodal metastases. and EBV are associated with different genomic imbalances, suggesting that these infectious agents exert different influences in the development of gastric carcinoma.

Adult↗