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Ling Chen

Publications and source records attributed to Ling Chen.

At least 109 records · Page 6Linked to original sources
PubMed2003

Lu8Te and Lu7Te. Novel substitutional derivatives of lutetium metal.

Monocrystals of Lu8Te are synthesized by disproportionation of Lu7Te at 1000-1200 degrees C or by direct reaction of Lu plus Lu2Te3 at 1000 degrees C for 2 weeks. Lu7Te is produced by arc-melting of a suitable Lu-Lu2Te3 mixture, with good crystals being formed by subsequent annealing at 1300 degrees C. The structures of Lu8Te (P2m, Z = 1) and Lu7Te (Cmcm, Z = 4) exhibit simple AB... packing of distorted, not close-packed, layers along one short axis (, , respectively). Puckered Lu, Te layers are stacked normal to (010) or (001) in six- or eight-layer repeat sequences, with Te substituting for every third or every other Lu in every third or fourth layer, respectively. Strong Lu-Te bonding is indicated. Both Te substitutions decrease the volume per atom from that in hcp. Lu and also decrease the coordination number of all atoms from 12 to 9-11.

Journal Article↗
PubMed2003

Comparative analysis of the effects of packaging signal, transgene orientation, promoters, polyadenylation signals, and E3 region on growth properties of first-generation adenoviruses.

First-generation adenovectors have been developed for gene therapy and vaccine applications. The construction of these adenovectors has entailed the use of numerous types of expression cassettes. It has long been known that first-generation adenovectors can be rescued more easily and to higher titers with some transgenes than with others. This study has systematically shown that there can be marked differences in growth properties of recombinant adenovectors attributable to the use of promoters, the orientation of the transgene within the E1A/E1B-deleted region, and the inclusion of the E3 region. In addition, we had demonstrated the benefit of extending the packaging signal region to include elements V, VI, and VII. The effects of the complete packaging region were studied by plasmid competition studies between original and modified adenovectors. Similar competition studies between E3(+) and E3(-) adenovectors were performed and showed that the E3(+) vector had a growth advantage over its E3(-) counterpart. By making various changes, we have enhanced the growth capacity of our recombinant adenovector by more than 3-fold under serum-free and cell suspension growth conditions. Along with this enhanced growth, our adenovectors have maintained their genetic stability after 21 successive passages in cell culture. This increased robustness will be critical when adapting first-generation recombinant adenovectors to commercial production.

Adenoviridae↗
PubMed2003

Probing the activation site of ribonuclease L with new N6-substituted 2',5'-adenylate trimers.

2-5A trimer [5'-monophosphoryladenylyl(2'-5')adenylyl(2'-5')adenosine] activates RNase L. While the 5'-terminal and 2'-terminal adenosine N(6)-amino groups play a key role in binding to and activation of RNase L, the exocyclic amino function of the second adenylate (from the 5'-terminus) plays a relatively minor role in 2-5A's biological activity. To probe the available space proximal to the amino function of the central adenylate of 2-5A trimer during binding to RNase L, a variety of substituents were placed at that position. To accomplish this, the convertible building block 5'-O-dimethoxytrityl-3'-O-(tert-butyldimethylsilyl)-6-(2,4-dinitrophenyl)thioinosine 2'-(2-cyanoethylN,N-diisopropylphosphoramidite) was prepared as a synthon to introduce 6-(2,4-dinitrophenyl)thioinosine into the middle position of the 2-5A trimer during automated synthesis. Post-synthetic treatment with aqueous amines transformed the (2,4-dinitrophenyl)thioinosine into N(6)-substituted adenosines. Assays of these modified trimers for their ability to bind and activate RNase L showed that activation activity could be retained, albeit with some sacrifice compared to unmodified p5'A2'p5'A2'p5'A. Thus, the spatial domain about this N(6)-amino function could be available for modifications to enhance the biological potency of 2-5A analogues and to ligate 2-5A to targeting vehicles such as antisense molecules.

Animals↗
PubMed2003

Effect of vaccine delivery system on the induction of HPV16L1-specific humoral and cell-mediated immune responses in immunized rhesus macaques.

There have been numerous studies to assess the immunogenicity of candidate therapeutic and prophylactic vaccines for human papillomavirus (HPV), but few of them have directly compared different vaccines in an immunologically relevant animal system. In the present study, several vaccine delivery systems (VLPs, chimeric VLPs, plasmid DNA, and a replication incompetent adenoviral vector) expressing HPV16L1 were evaluated for their ability to induce HPV16L1 VLP-specific humoral immune responses, including neutralizing antibodies, and cell-mediated immune responses in rhesus macaques. Monkeys immunized with HPV16L1 VLPs mounted a potent humoral response with strongly neutralizing antibodies and a strong L1-specific Th2 response as measured by IL-4 production by CD4+ T cells. Monkeys immunized with plasmid DNA or an adenoviral vector expressing HPV16L1 showed strong Th1/Tc1 responses as measured by IFN-gamma production by CD4+ and/or CD8+ T cells and potent humoral responses, but only weakly neutralizing antibodies. These data demonstrate that the nature of the immune response against HPV16L1 is dramatically different when it is introduced via different delivery systems. Additionally, these findings support the notion that an HPV16L1 VLP-based vaccine will induce the strongly neutralizing antibodies necessary for effective prophylaxis.

Adenoviridae↗
PubMed2003

A new species of yunnanozoan with implications for deuterostome evolution.

Yunnanozoans are a distinctive clade of Lower Cambrian metazoans. Although widely accepted as deuterostomes, their exact placement within this superphylum is controversial. Here we describe a new species of Haikouella (H. jianshanensis) from the Chengjiang Lagerstätte (Yunnan, China) with exceptional preservation of a number of features. These include external gills, which suggest that the origin of the pharyngeal clefts was independent of the gills. The diagnostic branchial arches of chordates may, therefore, be composite structures. No evidence was found for the chordate-like structures that have been described in other yunnanozoans. We propose that yunnanozoans are stem-group deuterostomes, allied to the vetulicolians.

Animals↗
PubMed2003

Remarkable metal-rich ternary chalcogenides Sc14M3Te8 (M = Ru, Os).

In this novel motif, scandium atoms define infinite parallel chains of alternate trans-face-sharing cubes and pairs of square antiprisms in which each polyhedron is also centered by an M atom (M = Ru, Os). These chains are further linked into a three-dimensional structure by Sc(Te2Te4/2) octahedra. Physical property measurements show Sc14Ru3Te8 to be metallic and Pauli-paramagnetic, consistent with the results of extended Hückel band structure calculations. Matrix effects are evident in the dimensions within the chains. The major interactions are Sc-M and Sc-Te.

Journal Article↗
PubMed2003

Proteomic identification of heat shock protein 70 as a candidate target for enhancing apoptosis induced by farnesyl transferase inhibitor.

Farnesyl transferase inhibitors (FTIs) are novel antitumor drugs with clinical activity. FTIs inhibit cell growth not only by preventing direct Ras farnesylation but also through a Ras-independent pathway. Proteomics has been shown to be a powerful tool to monitor and analyze molecular networks and fluxes within the living cells and to identify the proteins that participate in these networks upon perturbation of the cellular environment. To observe early and dynamic protein changes in the cellular response to FTI in ovarian cancer cells, total proteins were extracted from 2774 cells treated or not with 10 microM manumycin, an FTI, for 3, 6 and 16 h. The proteins in the cells that were differentially expressed following treatment with manumycin for 3, 6 and 16 h were noted by two-dimensional electrophoresis and further identified by peptide mass fingerprinting as stress proteins. Both heat shock protein 70 (HSP70) and altered HSP70 were significantly up-regulated as early as 16 h in 2774 cells after exposure to manumycin. Since HSP70 plays an important role in protecting cells under stress, we treated the 2774 cells with the HSP inhibitor quercetin in combination with FTI. Quercetin dramatically enhanced the manumycin-mediated apoptosis in 2774 cells. Inducible HSP70 by manumycin in surviving ovarian cancer cells was also inhibited by quercetin as demonstrated by enzyme-linked immunosorbent assay. The inhibition of HSP70 by quercetin was correlated with enhancement of manumycin-induced mediated apoptosis in 2774 cells. The inhibition of HSP70 by 50 microM quercetin was also correlated with a decreased expression of procaspase-3 and enhancement of specific cleavage of poly (ADP-ribose) polymerase into apoptotic fragment in 2774 cells treated with manumycin. The interaction between the HSP70 inhibitor and FTI confirms the functional significance of the up-regulation of HSP70 as a protective mechanism against FTI-induced apoptosis and provides the framework for combination treatment of ovarian cancer.

Alkyl and Aryl Transferases↗
PubMed2003

Generation and characterization of chimeric recombinant AAV vectors.

Although most animal experiments with recombinant adeno-associated virus (AAV) vectors have been based on AAV serotype 2, recent studies showed that AAV vectors based on AAV serotype 1 performed more efficiently in muscle and other tissues. On the other hand, AAV2-based vectors can be readily purified by heparin column. To combine the advantages of both types of vectors, we developed a strategy to generate chimeric vectors by using a mixture of AAV helper plasmids encoding both serotypes in the transfection process. Because the AAV packaging machinery cannot distinguish between closely related AAV1 and AAV2 capsid proteins, each packaged virion contains capsid proteins from both serotypes. As expected, the resulting chimeric vectors could be purified by heparin column. Neutralizing antibody assays showed that the chimeric vectors can be inhibited by either AAV1 or AAV2 antiserum. In vivo, the chimeric vectors direct levels of expression similar to those of AAV1 in muscle or AAV2 in liver; that is, they combine the best transduction characteristics of both parent vectors. In summary, this study provides a straightforward method for combining various properties of different AAV serotypes into one vector. Potential limitations of the chimeric vectors are also discussed.

Animals↗
PubMed2003

Macrophages and MHC class II positive dendritiform cells in the iris and choroid of the pig.

PURPOSE: Macrophages and dendritic cells (DC) are considered to play an important role in the initiation and propagation of uveitis. Little is known about these cells in the normal pig uveal tract, despite the fact that the pig eye shares many similarities with the human eye and is considered as a suitable species to investigate the pathogenesis of human ocular disease. The aim of this study was to investigate the presence of immunocompetent cells in the uveal tract of the normal pig. METHODS: Iris and choroid wholemounts and cryostat sections were obtained from normal pig eyes. Single and double immunohistochemistry was performed by using anti-porcine leukocyte (CD45), anti-porcine macrophage (CD163, CD14), anti-porcine MHC class II (MCA1335), anti-human MHC class II (MCA379G), anti-porcine B lymphocyte (IgM), anti-porcine T lymphocyte (CD6) and anti-porcine granulocyte (MCA1219) monoclonal antibodies. RESULTS: A rich network of dendritiform CD163 positive tissue macrophages was observed in normal pig iris and choroid wholemounts (368 + 84/mm(2), 402 + 97/mm(2), respectively). Approximately 50% of the CD163 positive tissue macrophages in the iris coexpressed MHC class II. Double immunostaining revealed that a small population of the MHC class II positive cells, did not express macrophage markers, and probably represent classical DCs. B lymphocytes and granulocytes were not detected in iris and choroid wholemounts. An occasional T cell could be observed per high power field in iris wholemounts but not in the choroid. CONCLUSIONS: The present study reveals that the normal pig uveal tract contains a rich network of tissue macrophages and MHC class II positive dendritiform cells. At least three populations could be distinguished: MHC class II positive and negative tissue macrophages and MHC class II+ dendritiform cells lacking tissue macrophage markers.

Animals↗
PubMed2003

Comparative immunogenicity in rhesus monkeys of DNA plasmid, recombinant vaccinia virus, and replication-defective adenovirus vectors expressing a human immunodeficiency virus type 1 gag gene.

Cellular immune responses, particularly those associated with CD3(+) CD8(+) cytotoxic T lymphocytes (CTL), play a primary role in controlling viral infection, including persistent infection with human immunodeficiency virus type 1 (HIV-1). Accordingly, recent HIV-1 vaccine research efforts have focused on establishing the optimal means of eliciting such antiviral CTL immune responses. We evaluated several DNA vaccine formulations, a modified vaccinia virus Ankara vector, and a replication-defective adenovirus serotype 5 (Ad5) vector, each expressing the same codon-optimized HIV-1 gag gene for immunogenicity in rhesus monkeys. The DNA vaccines were formulated with and without one of two chemical adjuvants (aluminum phosphate and CRL1005). The Ad5-gag vector was the most effective in eliciting anti-Gag CTL. The vaccine produced both CD4(+) and CD8(+) T-cell responses, with the latter consistently being the dominant component. To determine the effect of existing antiadenovirus immunity on Ad5-gag-induced immune responses, monkeys were exposed to adenovirus subtype 5 that did not encode antigen prior to immunization with Ad5-gag. The resulting anti-Gag T-cell responses were attenuated but not abolished. Regimens that involved priming with different DNA vaccine formulations followed by boosting with the adenovirus vector were also compared. Of the formulations tested, the DNA-CRL1005 vaccine primed T-cell responses most effectively and provided the best overall immune responses after boosting with Ad5-gag. These results are suggestive of an immunization strategy for humans that are centered on use of the adenovirus vector and in which existing adenovirus immunity may be overcome by combined immunization with adjuvanted DNA and adenovirus vector boosting.

AIDS Vaccines↗
PubMed2003

Vaccine-induced immunity in baboons by using DNA and replication-incompetent adenovirus type 5 vectors expressing a human immunodeficiency virus type 1 gag gene.

The cellular immunogenicity of formulated plasmid DNA and replication-defective human adenovirus serotype 5 (Ad5) vaccine vectors expressing a codon-optimized human immunodeficiency virus type 1 gag gene was examined in baboons. The Ad5 vaccine was capable of inducing consistently strong, long-lived CD8(+)-biased T-cell responses and in vitro cytotoxic activities. The DNA vaccine-elicited immune responses were weaker than those elicited by the Ad5 vaccine and highly variable; formulation with chemical adjuvants led to moderate increases in the levels of Gag-specific T cells. Increasing the DNA-primed responses with booster doses of either Ad5 or modified vaccinia virus Ankara vaccines suggests a difference in the relative levels of cytotoxic and helper responses. The implications of these results are discussed.

AIDS Vaccines↗
PubMed2003

Clinical study for alleviating opiate drug psychological dependence by a method of ablating the nucleus accumbens with stereotactic surgery.

The aim of this study was to explore a new way of treating drug addiction by ablating the nucleus accumbens (NAC), which has a close relationship with drug-induced psychological dependence, using stereotactic surgery, blocking the mesocorticolimbic dopamine circuit, alleviating craving for drugs and lowering the relapse rate after detoxification. On the basis of animal experiments, stereotactic surgery was performed in 28 patients by making a lesion in the NAC bilaterally to treat opiate drug dependence. Indications, the criterion of therapeutic effect, treatment process and the therapeutic and safety evaluation index of the surgery were formulated particularly. The mean follow-up period was 15 months. Relapse has not occurred in 11 cases up till now. Drug-free time in these patients has been more than half a year in 4 cases (more than a year in 3 cases), and less than half a year in 7 cases. Relapse occurred in 15 cases after surgery. Drug-free time in these patients was more than half a year in 3 cases, between 1 month and half a year in 10 cases and less than 1 month in 2 cases. The therapeutic effect was excellent in 7 cases (26.9%), good in 10 cases (38.5%) and poor in 2 cases (7.7%). Another 7 cases were still under investigation at the time of writing. Relapse rates after surgery were 7.7, 38.5 and 57.5% within 1 month, between 1 month and half a year and after more than half a year, respectively. There were no common complications of surgery such as intracranial hematoma or infection in these patients after operation. Character type was changed slightly in 2 cases, and 4 cases suffered temporary memory loss, which did not affect their daily lives and learning function. They all recovered within 1 month. There were different degrees of effectiveness of treating drug addicts' psychological dependence by making lesions in the NAC bilaterally with stereotactic surgery. No particular complications occurred. The operation is safe and feasible. The mean follow-up time in this study was 15 months. The effectiveness was satisfactory. The relapse rate of drug addicts after detoxification was clearly reduced.

Follow-Up Studies↗
PubMed2003

Separation and identification of differentially expressed nuclear matrix proteins between human esophageal immortalized and carcinomatous cell lines.

AIM: To separate and identify differentially expressed nuclear matrix proteins (NMPs) between the immortalized human esophageal epithelial cell line (SHEE) and the malignantly transformed esophageal carcinoma cell line (SHEEC), and to provide new ways for finding specific markers and the pathogenesis of esophageal carcinoma. METHODS: SHEE and SHEEC cell lines were used to extract NMPs. The quality of NMPs was monitored by Western blot analysis including DNA topoisomerase IIalpha, proliferation cell nuclear antigen (PCNA) and histone. NMPs of SHEE and SHEEC were analyzed by two-dimensional electrophoresis (2-DE), silver staining and PDQuest6.2 image analysis software. Three spots in which the differentially expressed NMPs were more obvious, were selected and analyzed with matrix-assisted laser desorption/ionization time of flying mass spectrometry (MALDI- TOF-MS) and database search. RESULTS: Western blot analysis revealed that DNA topoisomerase IIalpha and PCNA were detected, and the majority of histones were deleted in NMPs of SHEE and SHEEC. After 2-DE image analysis by PDQuest6.2 software, the 2-DE maps were detected with an average of 106+/-7.1 spots in SHEE and 132+/-5.0 spots in SHEEC. Most of them were matched one another (r=0.72), only 16 protein spots were found differing in intensity. Three NMPs including cytoskeletal tropomyosin, FK506-binding protein 6, similar to retinoblastoma binding protein 8 were preliminarily identified by MALDI- TOF-MS. CONCLUSION: These differentially expressed NMPs may play an important role during malignant transformation from SHEE to SHEEC. Their separation and identification will contribute to searching for specific markers and probing into the pathogenesis of esophageal carcinoma.

Blotting, Western↗
PubMed2003

[Roentgenography and CT appearance in patients with severe acute respiratory syndrome].

OBJECTIVE: To evaluate the appearance and dynamic change of chest roentgenography and CT in patients with severe acute respiratory syndrome (SARS). METHODS: Serial roentgenography and CT of 61 confirmed SARS patients were analyzed. RESULTS: The onset symptom was fever in all patients. In the early phase of SARS, the main abnormal appearance was single or bilateral localized patchy clouding opacity on roentgenography, which progressed rapidly. The area of opacity peaked at about 2 weeks, involving the majority area of the lung in 57% of the patients. The area involved was correlated with the severity of clinical symptoms. The opacity disappeared gradually in 5 weeks in 84% of the patients. Lungs complicated infection were found in 6 patients with a prolonged duration of the illness. Among the 61 patients, 4 died. CT scan was performed in 16 SARS patients in the recovery phase, of whom 13 showed lung fibrosis. CONCLUSIONS: Lung infiltration in early phase develops rapidly and involves most area of the lung in advanced phase in most SARS patients. Lungs fibrosis was found in some patients in the recovery phase.

Adult↗
PubMed2003

[Study on activated carbon regeneration by heterogeneous catalytic wet oxidation].

The CuO-Al2O3 catalyzer was used to heterogeneous catalytic wet oxidation regeneration of activated carbon, which adsorbed the phenol saturated. The study found the effect of reaction factors on activated carbon regeneration by heterogeneous catalytic wet oxidation. And the optimum reaction condition was reaction temperature 210 degrees C, reaction time 60 min, catalyzer dosage 25 mg (calculated by Cu), reaction oxygen pressure 0.6 MPa at 25 degrees C, carbon 15 g (dry carbon), distilled water 300 mL. It was found that the catalyzer had good stability in this experiment by using X-rey radiation analysing catalyzer and experiment on catalyzer stability.

Carbon↗
PubMed2003

[Study on exons 3 and 4 of alpha-synuclein gene in Chinese familial Parkinson disease patients].

OBJECTIVE: To study the relationship of Chinese familial Parkinson disease with alpha-synuclein gene. METHODS: Polymerase chain reaction-single strand conformational polymorphism (PCR-SSCP) and polymerase chain reaction-heteroduplex analysis(PCR-HA) were employed to detect the abnormal mobilization in the familial Parkinson disease and sporadic Parkinson disease patients, then it was verified by gene sequencing. RESULTS: No mutation was found in alpha-synuclein gene exons 3 and 4 by PCR-SSCP together with PCR-HA. An inserted c and an inserted t were found in intron 4, position 23 and position 67 respectively. CONCLUSION: (1) Exons 3 and 4 of alpha-synuclein gene are not the mutational hot spots of Chinese familial Parkinson disease. (2) Two polymorphisms were found in intron 4 of alpha-synuclein gene. They are 23 ins c and 67 ins t.

Adult↗