PubMed Health⌕ Search

Biomedical subjects

Lin Tang

Publications and source records attributed to Lin Tang.

At least 37 records · Page 2Linked to original sources
PubMed2005

Immunogenicity and protective efficacy in monkeys of purified inactivated Vero-cell SARS vaccine.

BACKGROUND: In 2003, severe acute respiratory syndrome (SARS) resulted in hundreds of infections and deaths globally. We aim to assess immunogenicity and protective efficacy of purified inactivated Vero-cell SARS vaccine in monkeys. METHODS: The cultures of SARS coronavirus (SARS-CoV) BJ-01 strain infected Vero cells were inactivated with beta-propiolactone. Sequential procedures, including ultrafiltration, gel filtration and ion exchange chromatography, were performed to obtain purified inactivated SARS vaccine. The purified SARS vaccine was analyzed with electron microscope, HPLC and Western blotting. We immunized three groups of cynomolgus macaques fascicularis with adjuvant-containing purified vaccine, purified vaccine and unpurified vaccine, respectively, and a fourth group served as a control. Antibody titers were measured by plaque reduction neutralization test. The vaccinated monkeys were challenged with SARS-CoV BJ-01 strain to observe protective efficacy. Additionally, three groups of rhesus monkeys were immunized with different doses of the purified inactivated SARS vaccine (0.5, 1 and 2mug/time/monkey) on days 0 and 7, and the monkeys were challenged with SARS-CoV GZ-01 strain. We assessed the safety of the SARS vaccine and observed whether the antibody dependent enhancement (ADE) occurred under low levels of neutralizing antibody in rhesus. FINDINGS: The purity of SARS vaccine was 97.6% by HPLC identification and reacted with convalescent sera of SARS patients. The purified SARS vaccine induced high levels of neutralizing antibodies and prevented the replication of SARS-CoV in monkeys. Under low levels of neutralizing antibody, no exacerbation of clinical symptoms was observed when the immunized monkeys were challenged with SARS-CoV. In this preliminary animal trial, no side effects were detected when monkeys were immunized with purified SARS vaccine either at normal or large doses. INTERPRETATION: The purified inactivated SARS vaccine could induce high levels of neutralizing antibody, and protect the monkeys from the challenge of SARS-CoV. The SARS vaccine prepared in the study appeared to be safe in monkeys.

Animals↗
PubMed2005

Expression of heparanase mRNA in anti-sense oligonucleotide-transfected human esophageal cancer EC9706 cells.

AIM: To investigate the effects of anti-sense oligonucleotides (ASODNs) on mRNA expression of heparanase in human esophageal cancer EC9706 cells. METHODS: One non-sense oligonucleotide (N-ODN) and five ASODNs against different heparanase mRNA sites were transfected into EC9706 cells, then the expression of heparanase mRNA in EC9706 cells was studied by in situ hybridization. RESULTS: The expression of heparanase mRNA could be inhibited by ASODNs. There was no significant difference among five ASODNs (P>0.05), but there was a significant difference between ASODNs and N-ODN or non-transfected group (ASODN1: 2.25+/-0.25, ASODN2: 2.21+/-0.23, ASODN3: 2.23+/-0.23, ASODN4: 2.25+/-0.24 vs N-ODN: 3.47+/-2.80 or non- transfected group: 3.51+/-2.93 respectively, P<0.05). CONCLUSION: The expression of heparanase mRNA in EC9706 cells can be inhibited by ASODNs in vivo, and heparanase ASODNs can inhibit metastasis of esophageal squamous cell carcinoma or other tumors by inhibiting the expression of heparanase.

Cell Line, Tumor↗
PubMed2005

Crystal structure of pyridoxal kinase in complex with roscovitine and derivatives.

Pyridoxal kinase (PDXK) catalyzes the phosphorylation of pyridoxal, pyridoxamine, and pyridoxine in the presence of ATP and Zn2+. This constitutes an essential step in the synthesis of pyridoxal 5'-phosphate (PLP), the active form of vitamin B6, a cofactor for over 140 enzymes. (R)-Roscovitine (CYC202, Seliciclib) is a relatively selective inhibitor of cyclin-dependent kinases (CDKs), currently evaluated for the treatment of cancers, neurodegenerative disorders, renal diseases, and several viral infections. Affinity chromatography investigations have shown that (R)-roscovitine also interacts with PDXK. To understand this interaction, we determined the crystal structure of PDXK in complex with (R)-roscovitine, N6-methyl-(R)-roscovitine, and O6-(R)-roscovitine, the two latter derivatives being designed to bind to PDXK but not to CDKs. Structural analysis revealed that these three roscovitines bind similarly in the pyridoxal-binding site of PDXK rather than in the anticipated ATP-binding site. The pyridoxal pocket has thus an unexpected ability to accommodate molecules different from and larger than pyridoxal. This work provides detailed structural information on the interactions between PDXK and roscovitine and analogs. It could also aid in the design of roscovitine derivatives displaying strict selectivity for either PDXK or CDKs.

Animals↗
PubMed2005

Roscovitine targets, protein kinases and pyridoxal kinase.

(R)-Roscovitine (CYC202) is often referred to as a "selective inhibitor of cyclin-dependent kinases." Besides its use as a biological tool in cell cycle, neuronal functions, and apoptosis studies, it is currently evaluated as a potential drug to treat cancers, neurodegenerative diseases, viral infections, and glomerulonephritis. We have investigated the selectivity of (R)-roscovitine using three different methods: 1) testing on a wide panel of purified kinases that, along with previously published data, now reaches 151 kinases; 2) identifying roscovitine-binding proteins from various tissue and cell types following their affinity chromatography purification on immobilized roscovitine; 3) investigating the effects of roscovitine on cells deprived of one of its targets, CDK2. Altogether, the results show that (R)-roscovitine is rather selective for CDKs, in fact most kinases are not affected. However, it binds an unexpected, non-protein kinase target, pyridoxal kinase, the enzyme responsible for phosphorylation and activation of vitamin B6. These results could help in interpreting the cellular actions of (R)-roscovitine but also in guiding the synthesis of more selective roscovitine analogs.

Adenosine Triphosphate↗
PubMed2005

Genetic diversity and genetic structure of an endangered species, Trillium tschonoskii.

The genetic diversity and genetic structure of Trillium tschonoskii (Maxim) were investigated using amplified fragment length polymorphism markers. Eight primer combinations were carried out on 105 different individuals sampled from seven populations. Of the 619 discernible DNA fragments generated, 169 (27.3%) were polymorphic. The percentage of polymorphic bands within populations ranged from 4.52 to 10.50. Genetic diversity (H(E)) within populations ranged from 0.0130 to 0.0379, averaging 0.0536 at the species level. Genetic differentiation among populations was detected based on Nei's genetic diversity analysis (53.03%) and analysis of molecular variance (AMOVA) (52.43%). AMOVA indicated significant genetic differentiation among populations (52.43% of the variance) and within populations (47.57% of the variance) (p < 0.0002). Gene flow was low (0.4429) among populations. Species breeding system and limited gene flow among populations are plausible reasons for the high genetic differentiation observed for this species. We propose an appropriate strategy for conserving the genetic resources of T. tschonoskii in China.

China↗
PubMed2005

Structural evidence for alpha-synuclein fibrils using in situ atomic force microscopy.

Human alpha-synuclein is a presynaptic terminal protein and can form insoluble fibrils that are believed to play an important role in the pathogenesis of several neurodegenerative diseases such as Parkinson's disease, dementia with Lewy bodies and Lewy body variant of Alzheimer's disease. In this paper, in situ atomic force microscopy has been used to study the structural properties of alpha-synuclein fibrils in solution using two different atomic force microscopy imaging modes: tapping mode and contact mode. In the in situ contact mode atomic force microscopy experiments alpha-synuclein fibrils quickly broke into fragments, and a similar phenomenon was found using tapping mode atomic force microscopy in which alpha-synuclein fibrils were incubated with guanidine hydrochloride (0.6 M). The alpha-synuclein fibrils kept their original filamentous topography for over 1 h in the in situ tapping mode atomic force microscopy experiments. The present results provide indirect evidence on how beta-sheets assemble into alpha-synuclein fibrils on a nanometer scale.

Guanidine↗
PubMed2005

[Effects of metformin on fatty liver in insulin-resistant rats].

OBJECTIVES: To investigate the effects of metformin on fatty livers in insulin-resistant rats. METHODS: Thirty-one male Wistar rats were randomly divided into a normal (n=8) and an experimental group (n=23). The normal group rats were fed a standard diet, and those of the experimental group with a high-fat diet. After 8 weeks, 7 rats from the experimental group were sacrificed to verify whether the model was established successfully. Then the experimental group was randomly subdivided into two groups: one with metformin treatment (n=8) and one without (n=8). After 6 weeks, insulin sensitivity was measured with glucose infusion rate (GIR) by euglycermic hyperinsulinemia clamp technique. Aminotransferase, triglyceride (TG) and free fatty acids (FFA) were measured by biochemical methods, insulin by radioimmunoassay and tumor necrosis factor-alpha (TNF alpha) by ELISA. The steatosis changes and inflammation activity of all rat livers were scored histologically. RESULTS: Compared with the model group, the insulin resistance, liver index, visceral adiposity and weight loss of the metformin group were dramatically ameliorated. The steatosis and the inflammatory activity in the livers and the level of serum aminotransferase of the metformin group were also significantly decreased. Furthermore, metformin treatment lowered serum TG, liver lipid accumulation and the production of FFA and TNF alpha. CONCLUSION: Metformin can significantly improved insulin resistance and fatty liver development in rats fed a high-fat diet. It may become a new choice for fatty liver treatment in the future.

Animals↗
PubMed2004

Origin of the murine implantation serine proteinase subfamily.

The S1 serine protease family is one of the largest gene families known. Within this family there are several subfamilies that have been grouped together as a result of sequence comparisons and substrate identification. The grouping of related genes allows for the speculation of function for newly found members by comparison and for novel subfamilies by contrast. Analysis of the evolutionary patterns of genes indicates whether or not orthologs are likely to be identified in other species as well as potentially indicating that hypothesized orthologs are in fact not. Looking at subtle differences between subfamily members can reveal intricacies about function and expression. Previously, we have described genes encoding two novel serine proteinases, ISP1 and ISP2, which are most closely related to tryptases. The ISP1 gene encodes the embryo-derived enzyme strypsin, which is necessary for blastocyst hatching and invasion in vitro. Additionally both ISP1 and ISP2 are co-expressed in the endometrial gland during the time of hatching, suggesting that they may also both participate in zona lysis from within the uterine lumen. Here, we demonstrate that the ISPs are tandemly linked within the tryptase cluster on 17A3.3. We suggest that remarkable similarities within the 5'-untranslated and first intron regions of ISP1 and ISP2 may explain their intimate co-regulation in uterus. We also suggest that ISP genes have evolved through gene duplication and that the ISP1 gene has also begun to adopt an additional new function in the murine preimplantation embryo.

Amino Acid Sequence↗
PubMed2004

Inactivated SARS-CoV vaccine prepared from whole virus induces a high level of neutralizing antibodies in BALB/c mice.

We tested the ability of inactivated SARS-CoV vaccine to induce neutralizing antibodies in BALB/c mice. The inactivated vaccine was prepared by SARS-CoV virus propagation in Vero cells, with subsequent beta-propiolactone inactivation and Sepharose 4FF column chromatography purification. One hundred forty BALB/c female mice were divided into seven groups of 20 mice each. Of the seven groups, three groups were inoculated with 0.1, 1, and 3 microg of the vaccine without adjuvant while three other groups were inoculated at the same three dosages of vaccine with aluminum hydroxide as adjuvant, respectively. The remaining group was set up as a blank control. Each mouse was inoculated twice at an interval of 3 weeks. One week after the second immunization, mice sera were collected to detect serum neutralizing antibodies. An assay for determining neutralizing antibody titers was developed. The results can be summarized as follows: (1) higher dosages of vaccine induced higher levels of neutralizing antibody titer; (2) the level of neutralizing antibodies induced by the inoculation with aluminum hydroxide adjuvant was slightly higher than that without adjuvant, but the difference was not statistically significant.

Aluminum Hydroxide↗
PubMed2004

[Construction and identification of expressing siRNA plasmid against human augmenter of liver regeneration].

OBJECTIVES: To detect whether there is an expression of human augmenter of liver regeneration (hALR) in HepG2 cells. To develop a kind of RNAi that specifically targets human augmenter of liver regeneration by synthesizing small interfering RNA (siRNA) in vivo, and to assess the inhibitory effect of this siRNA on hALR expression. METHODS: The expression of hALR in HepG2 cells was observed with immunocytochemistry. The RNAi plasmid pSIALR-A and the unrelated control plasmid pSIALR-B were transfected into HepG2 cells. Forty-eight hours after transfection, the protein level of hALR was measured with immunocytochemistry; meanwhile, the reverse transcription PCR (RT-PCR) was performed to detect the expression of hALR mRNA. RESULTS: hALR was expressed by HepG2 cells. siRNA plasmid pSIALR-A, which targets the cDNA of hALR and the unrelated control plasmid pSIALR-B, was successfully constructed. Both immunocytochemistry and RT-PCR showed that pSIALR-A inhibited the expression of hALR in HepG2 cells significantly, compared with that of pSIALR-B. CONCLUSION: The results showed that the small interfering RNA targeting hALR suppresses the expression of hALR in a sequence-specific manner

Base Sequence↗
PubMed2004

[Study progress on determination of environmental trace toxicants by immunosensor].

Along with the advances in immunoassay and sensing techniques, the immunosensors based on specific immunoreaction and immobilized antibody (antigen) as recognition element were developed. They can be used for real-time, in-vivo and on-the-spot determination of pesticides, industrial organic pollutants, heavy metals, biotoxins, etc. with high sensitivity and selectivity. They possess a great potential for environmental monitoring. The working mechanism, fabrication and classification of immunosensor are briefly introduced in this paper. The latest study progress on immobilization methods and sensing techniques of immunosensor for determination of trace toxicants is reviewed. The application of immunosensor in environmental monitoring and the future development are also discussed.

Antigen-Antibody Reactions↗
PubMed2004

Plant regeneration from epicotyl explant of Jatropha curcas.

In vitro epicotyl explants from Jatropha curcas were cultured on MS medium with indole-3-butyric acid (IBA) and 6-benzyladenine (BA). Adventitious buds were directly induced from the surface of epicotyl explants under the condition with the combinations of IBA 0.1 mg/L and BA 0.2-0.7 mg/L. Of which IBA 0.1 mg/L and BA 0.5 mg/L induced the highest regeneration frequency. Shoot regeneration from callus required the combinations of IBA 0.5 mg/L with BA 0.1 mg/L, IBA 0.5 mg/L with BA 0.2 mg/L and IBA 1.0 mg/L with BA 0.5 mg/L, and the most suitable combination was IBA 1.0 mg/L and BA 0.5 mg/L. The health adventitious buds and regenerated shoots could be rooted on growth regulator-free MS medium. Regenerated plants with well developed shoots and roots were successfully transferred to greenhouse, without visible detectable variation.

Adenine↗
PubMed2004

[Determination of crocin-1 in rabbit plasma and the pharmacokinetics by RP-HPLC].

AIM: To develop a sensitive and specific HPLC method for the determination of crocin-1 in rabbit plasma, and study the pharmacokinetics in rabbit. METHODS: After i.v. administration of crocin-1 in rabbit, the sample could be well purified after precipitation of protein with methanol. Waters spherisorb C18 column (250 mm x 4.6 mm ID, 5 microm) was used and the mobile phase consisted of methanol-acetonitrile-1% aqueous acetic acid (15:10:50) at the flow rate of 1 mL x min(-1), and the UV detection wave length was 440 nm. The column temperature is 25 degrees C. RESULTS: The calibration curve was linear (r = 0.9997) in the range from 0.86 to 27.54 mg x L(-1) for crocin-1. The lowest detectable concentration of crocin-1 was 0.42 mg x L(-1). After given i.v. crocin-1 in rabbit, the concentration-time curves of crocin-1 was shown to fit two-compartment open model. CONCLUSION: This method is proved to be rapid, precise and reliable enough to be applied to the pharmacokinetics studies of crocin-1 in rabbit.

Animals↗
PubMed2003

A peptide motif consisting of glycine, alanine, and valine is required for the fibrillization and cytotoxicity of human alpha-synuclein.

Amyloid-like aggregation or fibrillization of alpha-synuclein (alpha-Syn) and the filamentous deposits in Lewy bodies are believed to be closely associated with several fatal neurodegenerative disorders, including Parkinson's disease and Alzheimer's disease. Here, we report the importance of a nine-residue peptide motif, (66)VGGAVVTGV(74), in the fibrillization and cytotoxicity of human alpha-Syn. Mutagenesis combined with thioflavin T fluorescence detection, atomic force microscopic imaging, and cytotoxicity assays reveal that deletion of this sequence completely eliminates alpha-Syn fibrillization and cell toxicity. However, deletion of the (71)VTGV(74) sequence decreases the fibrillization rate while the cytotoxicity remains unchanged. Incorporation of charged residues within this region slows aggregation and even impedes filament formation. In addition, substitution of Gly68 with Ala or C-terminal truncations of alpha-Syn accelerate the fibrillization processes. Circular dichroism studies suggest that beta-sheet formation is often concomitant with filament formation. Thus, this segment, namely, the GAV motif, is responsible for aggregation or fibrillization of alpha-Syn and perhaps other amyloidogenic proteins. The oligomers formed during fibrillogenesis might be associated with the cytotoxicities of various alpha-Syn species. This finding may provide further insight into the understanding of the molecular mechanism underlying the fibrillogenesis implicated in neurodegeneration as well as aid in drug design and development of transgenic models.

Alanine↗
PubMed2003

Recording performance of holographic diffraction gratings in dry films containing hyperbranched polyisophthalesters as polymeric binders.

By use of a photopolymerization-diffusion model, the diffraction efficiency of photopolymerizable recording dry films prepared from hyperbranched polyisophthalesters as polymeric binders was investigated. The recording characteristics of these films, i.e., spatial frequency, polymeric binder structure, exposure intensity, and modulation depth, are discussed in detail. For a given total exposure dose the diffraction efficiency first increases and then decreases with increasing exposure intensity, and this effect becomes more remarkable as the unsaturated concentration of polymeric binder increases. An optimum total exposure dose of 36 mJ cm(-2) and an exposure intensity of 0.4 mW cm(-2) were determined. A modulation depth of 1 was found to produce the highest diffraction efficiency. Longer-lasting gratings could be obtained by use of polymeric binders with higher cross-linking densities.

Journal Article↗
PubMed2003

Epigenetic silencing of multiple interferon pathway genes after cellular immortalization.

Abrogating cellular senescence is a necessary step in the formation of a cancer cell. Promoter hypermethylation is an epigenetic mechanism of gene regulation known to silence gene expression in carcinogenesis. Treatment of spontaneously immortal Li-Fraumeni fibroblasts with 5-aza-2'-deoxycytidine (5AZA-dC), an inhibitor of DNA methyltransferase (DNMT), induces a senescence-like state. We used microarrays containing 12 558 genes to determine the gene expression profile associated with cellular immortalization and also regulated by 5AZA-dC. Remarkably, among 85 genes with methylation-dependent downregulation (silencing) after immortalization, 39 (46%) are known to be regulated during interferon signaling, a known growth-suppressive pathway. This work indicates that gene silencing may be associated with an early event in carcinogenesis, cellular immortalization.

Antimetabolites, Antineoplastic↗
PubMed2003

A genome sequence of novel SARS-CoV isolates: the genotype, GD-Ins29, leads to a hypothesis of viral transmission in South China.

We report a complete genomic sequence of rare isolates (minor genotype) of the SARS-CoV from SARS patients in Guangdong, China, where the first few cases emerged. The most striking discovery from the isolate is an extra 29-nucleotide sequence located at the nucleotide positions between 27,863 and 27,864 (referred to the complete sequence of BJ01) within an overlapped region composed of BGI-PUP5 (BGI-postulated uncharacterized protein 5) and BGI-PUP6 upstream of the N (nucleocapsid) protein. The discovery of this minor genotype, GD-Ins29, suggests a significant genetic event and differentiates it from the previously reported genotype, the dominant form among all sequenced SARS-CoV isolates. A 17-nt segment of this extra sequence is identical to a segment of the same size in two human mRNA sequences that may interfere with viral replication and transcription in the cytosol of the infected cells. It provides a new avenue for the exploration of the virus-host interaction in viral evolution, host pathogenesis, and vaccine development.

Base Sequence↗