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Yong Liu

Publications and source records attributed to Yong Liu.

At least 199 records · Page 11Linked to original sources
PubMed2003

The E protein is a multifunctional membrane protein of SARS-CoV.

The E (envelope) protein is the smallest structural protein in all coronaviruses and is the only viral structural protein in which no variation has been detected. We conducted genome sequencing and phylogenetic analyses of SARS-CoV. Based on genome sequencing, we predicted the E protein is a transmembrane (TM) protein characterized by a TM region with strong hydrophobicity and alpha-helix conformation. We identified a segment (NH2-_L-Cys-A-Y-Cys-Cys-N_-COOH) in the carboxyl-terminal region of the E protein that appears to form three disulfide bonds with another segment of corresponding cysteines in the carboxyl-terminus of the S (spike) protein. These bonds point to a possible structural association between the E and S proteins. Our phylogenetic analyses of the E protein sequences in all published coronaviruses place SARS-CoV in an independent group in Coronaviridae and suggest a non-human animal origin.

Amino Acid Sequence↗
PubMed2003

Complete genome sequences of the SARS-CoV: the BJ Group (Isolates BJ01-BJ04).

Beijing has been one of the epicenters attacked most severely by the SARS-CoV (severe acute respiratory syndrome-associated coronavirus) since the first patient was diagnosed in one of the city's hospitals. We now report complete genome sequences of the BJ Group, including four isolates (Isolates BJ01, BJ02, BJ03, and BJ04) of the SARS-CoV. It is remarkable that all members of the BJ Group share a common haplotype, consisting of seven loci that differentiate the group from other isolates published to date. Among 42 substitutions uniquely identified from the BJ group, 32 are non-synonymous changes at the amino acid level. Rooted phylogenetic trees, proposed on the basis of haplotypes and other sequence variations of SARS-CoV isolates from Canada, USA, Singapore, and China, gave rise to different paradigms but positioned the BJ Group, together with the newly discovered GD01 (GD-Ins29) in the same clade, followed by the H-U Group (from Hong Kong to USA) and the H-T Group (from Hong Kong to Toronto), leaving the SP Group (Singapore) more distant. This result appears to suggest a possible transmission path from Guangdong to Beijing/Hong Kong, then to other countries and regions.

Genome, Viral↗
PubMed2003

Regulation of c-Jun N-terminal kinase activation in hydrogen peroxide induced neurotoxicity.

C-Jun N-terminal kinase 1 and 2 (JNK1/2) have been shown to be transiently activated and involved in neurotoxicity. We searched for possible upstream molecules, which are responsible for the regulation of hydrogen peroxide-(H2O2) induced JNK1/2 activation and JNK1/2-mediated apoptotic-like cell death in cultured rat cortical neurons. The results showed that JNK1/2 activation (monitored by anti-diphosphorylated JNK1/2 antibody) was largely prevented by elimination of extracellular Ca2+ or blockage of NMDA-receptors (NMDA-R), and was weakly but significantly decreased by blockage of L-type voltage-gated calcium channel (L-VGCC); furthermore, JNK1/2 activation was largely prevented by inhibition of Ca2+/calmodulin-dependent protein kinase-II (CaMKII) and protein-tyrosine kinases (PTK). We also found that H2O2-induced apoptotic-like cell death was partially prevented by elimination of extracellular Ca2+, or by inhibition of NMDA-R, L-VGCC, PTK and CaMKII, respectively. The above results suggest that in H2O2-induced neurotoxicity, JNK1/2 activation is mainly mediated by NMDA-R and L-VGCC. Consequently, PTK and CaMKII are critical intermediaries in JNK1/2 activation and are mainly responsible for JNK1/2-mediated apoptotic-like cell death.

Animals↗
PubMed2003

Cimidahuside 1 and 2, two new cyclolanostanol xylosides from the aerial parts of Cimicifuga dahurica.

Cimidahuside 1 and 2, two new cyclolanostanol xylosides were isolated from the aerial parts of Cimicifuga dahurica (Turcz.) MAXIM, on the basis of spectral data and chemical evidences, their structures were determined to be (20R,24R)-24,25-epoxy-3-beta-(beta-D-xylopyranosyloxy)-9,19-cyclolanost-7-ene-16,23-dione (1), and (20R,24R)-24,25-epxy-15-alpha-hydroxy-3-beta-((bet-D-xylpyranosyoxy)-9,19-cyclanost-7-ene-16,23-dione (2), respectively.

Cimicifuga↗
PubMed2003

Enteric disposition and recycling of flavonoids and ginkgo flavonoids.

OBJECTIVE: The objective of this study was to determine the intestinal and microbial disposition of flavonoids and how these disposition processes affect their enteric recycling. DESIGN: Studies were performed using a perfused rat intestinal model or using enrichment cultures and a pure isolate of Enterococcus avium (LY1). RESULTS: In the rat intestine, aglycones, such as quercetin and apigenin, were as permeable (P*(eff) > or = 2) as compounds such as propranolol (100% absorption). However, a significant portion of the absorbed aglycones was conjugated and the metabolites were excreted into the lumen. Flavonoid glycosides, such as isoquercitrin and apigenin-7-O-glucoside, also had high apparent P*(eff) values (> or = 2) in the upper small intestine because of rapid hydrolysis. However, isoquercitrin was absorbed much slower (P*(eff) < or = 0.7, p < 0.05) when hydrolysis was absent or inhibited by 20 mmol gluconolactone. Absorption of other intact glycosides was similar to intact isoquercitrin and was much slower than the corresponding aglycones (P*(eff) < or = 0.7, p < 0.05). Intestinal bacteria, such as LY1, hydrolyzed the flavonoid glycosides used in the study. Excreted glycosidases were involved in the hydrolysis of glycosides because glycosides were poorly taken up by LY1. In conclusion, glycosidase-catalyzed hydrolysis is a critical first step in the intestinal and microbial disposition of flavonoid glycosides. Aglycones were not only rapidly absorbed, but also rapidly metabolized into phase II conjugates, which were then excreted back into the lumen. Therefore, intestinal and microbial glycosidases and intestinal phase II enzymes make a significant contribution to the disposition of flavonoids via the proposed enteric and enterohepatic recycling scheme.

Animals↗
PubMed2003

Disparities in trends of hospitalization for potentially preventable chronic conditions among African Americans during the 1990s: implications and benchmarks.

OBJECTIVES: We compared trends in prevalence rates of preventable cardiovascular- and diabetes-related hospitalizations between African Americans and members of other major US racial/ethnic groups. METHODS: Standardized rates for 1991 to 1998 were derived from hospital and US census data for California. RESULTS: African Americans had significantly higher hospitalization rates in 1991, and discrepancies in rates continued to widen through 1998. Overall male and female rates were approximately 3 times higher for angina, 7 times higher for hypertension, between 7 and 8 times higher for congestive heart failure, and 10 times higher for diabetes. CONCLUSIONS: Widening disparities in cardiovascular- and diabetes-related health conditions were observed in this study, possibly owing to racial inequalities in provision of effective primary care.

Adult↗
PubMed2003

Analysis of spontaneous, gamma ray- and ethylnitrosourea-induced hprt mutants in HL-60 cells with multiplex PCR.

AIM: To explore the molecular spectra and mechanism of human hypoxanthine guanine phosphoribosyl transferase (hprt) gene mutation induced by ethyluitrosourea (ENU) and (60)Co gamma-rays. METHODS: Independent human promyelocytic leukemia cells (HL-60) mutants at the hprt locus were isolated from untreated, ethyluitrosourea (ENU) and (60)Co gamma-ray-exposed cells, respectively, and verified by two-way screening. The genetic changes underlying the mutation were determined by multiplex polymerase chain reaction (PCR) amplification and electrophoresis technique. RESULTS: With dosage increased, survival rate of plated cell reduced (in the group with dosage of ENU with 100-200 micro g/ml, P<0.01; in the group with dosage of (60)Co gamma-ray with 2-4 Gy, P<0.05) and mutational frequency increased (in the group of ENU 12.5-200.0 micro g/ml, P<0.05; in the group of (60)Co gamma-ray with 1-4 Gy, P<0.05) significantly. In the 13 spontaneous mutants analyzed, 92.3 % of mutant clones did not show any change in number or size of exon, a single exon was lost in 7.7 %, and no evidence indicated total gene deletion occurred in nine hprt exons. However, deletions were found in 79.7 % of ENU-induced mutations (62.5-89.4 %, P<0.01) and in 61.7 % of gamma-ray-induced mutations (28.6-76.5 %, P<0.01). There were deletion mutations in all 9 exons of hprt gene and the most of induced mutations were chain deletion with multiplex exons (97.9 % in gamma-ray-induced mutants, 88.1 % in ENU-induced mutants). CONCLUSION: The spectra of spontaneous mutations differs completely from that induced by EUN or (60)Co gamma-ray. Although both ENU and gamma-ray can cause destruction of genetic structure, mechanism of mutagenesis between them may be different.

Alkylating Agents↗
PubMed2003

Leptin receptor expression in the basolateral nucleus of amygdala of conditioned taste aversion rats.

AIM: To determine whether serum leptin level and the leptin receptor (OB-R) expression in the basolateral amygdala (BLA) change following conditioned taste aversion (CTA) formation. METHODS: The serum leptin concentration was measured by rat leptin RIA kit, long and short forms of leptin receptor (OB-Rb and OB-Ra) mRNA in the brain sections were examined by in situ hybridization (ISH) and the expression of OB-R was assessed by immunohistochemistry ABC method with a highly specific goat anti-OB-R antibody. RESULTS: The level of serum leptin didn't show significant difference between CTA and control group. Comparing with the control group, the CTA group had an increase on count of OB-R immunohistochemistry positive-stained cells in the BLA (127+/-12 vs 48+/-9 per 1 mm(2)). The OB-Rb mRNA expression level enhanced by 11.9 % in the BLA, while OB-Ra mRNA level increased by 7.4 % on the choroid plexus in CTA group. So BLA was supposed to be a region where interactions between gustatory and vagal signals take place. CONCLUSION: BLA is one of the sites, which are responsible for CTA formation in the brain. Leptin and OB-R maybe involved in neuronal communication for CTA. So leptin and its receptors probably take part in CTA and integration of autonomic and extroceptive information.

Amygdala↗
PubMed2003

Variation and significance of microtubules in rat volume overload cardiac hypertrophy.

OBJECTIVE: To investigate the function of microtubules in volume overload cardiac hypertrophy of rat. METHODS: The structure of microtubules was observed using an immunofluorescent microscope, while the pixel intensity and distribution of microtubule imaging was estimated from laser scanning confocal images of left ventricular cardiocytes immuno-labeled with an antibody to beta-tubulin. RESULTS: The pixels of the microtubule image taken just after volume overload were not evenly distributed. At 6 hours after overload, the pixel intensity of the microtubule image was decreased to less than 150 (arbitrary units), which was the same as the pixel intensity and distribution of the colchicine depolymerized microtubule image. The changes were partially recovered to 200 (arbitrary units) after 4 more days. The pixel intensity of the control microtubule image was 250 (arbitrary units) and had an even distribution. The structuring of the microtubules was more disordered as volume overload hypertrophy developed. CONCLUSIONS: There are disorders in the signal transduction pathways governing the hypertrophic response of cardiomyocytes in the hypertrophic myocardium and microtubule is one of the members of the signal transduction pathways governing the hypertrophic response of cardiomyocytes in the hypertrophic myocardium. The disordered microtubule array may be targeted during heart failure treatment.

Animals↗
PubMed2003

Effects of basic fibroblast growth factor on biological characteristics of osteoblasts.

OBJECTIVE: To elucidate the effects of exogenous basic fibroblast growth factor (bFGF) on biological characteristics of rat osteoblasts cultured in vitro. METHODS: The osteoblasts isolated from a Sprague-Dawley rat and cultured in vitro were treated with different concentrations of bFGF (5-50 ng/ml) respectively. At 24 hours after treatment, the proliferating cell nuclear antigen was measured with immunocytochemistry, alkaline phosphatase (ALP) activity was determined and the expression of transforming growth factor beta 1 (TGF-beta(1)) was detected to observe the effects of bFGF on growth and differentiation of osteoblasts. RESULTS: bFGF (5-50 ng/ml) could obviously promote the growth of osteoblasts. The intracellular expression of TGF-beta(1) mRNA increased significantly, but the intracellular ALP content decreased. CONCLUSIONS: bFGF can obviously stimulate the proliferation of osteoblasts and promote the synthesis of TGF-beta(1), but cannot promote the differentiation of osteoblasts.

Alkaline Phosphatase↗
PubMed2003

Heat shock protein 70 expression in the brain of rats with cerebral infarction after receiving vascular endothelial growth factor 165 gene therapy.

OBJECTIVE: To investigate the expression of heat shock protein 70 (HSP70) in the brain of rats with cerebral infarction after the administration of vascular endothelial growth factor 165 (VEGF165) gene therapy, thereby to provide molecular basis for clinical gene therapy of cerebral infarction. METHODS: Twenty-five Wistar rats were divided equally into 5 groups, namely normal control group, sham-operated control group, middle cerebral artery occlusion group (MACO group), eukaryotic expression plasmid group (pUCCAGGS group) and gene therapy group (receiving pUCCAGGS/hVEGF165).Rat models of permanent MACO was established by ligation with nylon suture, and in the latter two groups, pUCCAGGS or pUCCAGGS/ hVEGF165 was directly injected into the infarcted area. Seven days after the infarction, the rats were killed to obtain the brain tissues for immunohistochemical detection of HSP70 expression. RESULTS: In the rat brain cortex of the normal and sham-operated control group, similar low levels of HSP70 expression were detected (P >0.05), while in the MCAO group and pUCCAGGS group, HSP70 levels were both significantly higher (P <0.01), showing no differences between the latter two groups (P >0.05). Most intense HSP70 expression was detected in the gene therapy group (P <0.01). In the penumbra of the infarct area, MCAO, pUCCAGGS, and gene therapy group all had high expression levels of HSP70, which were comparable in the former two groups (P >0.05), with the highest expression levels occurring in the latter group. Within the infarct area, similar expression pattern was observed (P <0.01). CONCLUSION: The elevated HSP70 expression in response to VEGF165 gene therapy in the rats as observed in this study suggests the potency of VEGF165 gene to induce HSP70 expression.

Animals↗
PubMed2003

[Gene-enhanced tissue engineering: applications in osteoinduction using cultured mesenchymal stem cells transduced with the bFGF gene].

To investigate the effect of basic fibroblast growth factor(bFGF) gene transfection on the proliferation and differentiation of mesenchymal stem cells (MSCs) and to provide basis for accelerating bone defect repairing using gene-enhanced tissue engineering technology, Rabbit periosteum-derived MSCs were transfected with the full-length rat bFGF cDNA in vitro. The transient and stable gene expression of bFGF were determined by immunohistochemistry. The proliferation and the synthesis alkaline phosphatase (ALP) and osteocalcin(OC) of the transfected MSCs were also examined. The results showed that bFGF cDNA could be transferred into osteoblasts and expressed stably at least 4 weeks. The proliferation and OC content of genetically modified MSCs were increased significantly, whereas the ALP activity remained no change. In conclusion, transfer of gene encoding bFGF to MSCs increases its proliferation and osteogenesis property. Based on the successful conjunction of the existing techniques of tissue engineering with the novel possibilities offered by modern gene transfer technology, an innovative concept, molecular tissue engineering, was put forward for the first time. As a new branch of tissue engineering, it represents both a new area and an important trend in tissue engineering research.

Alkaline Phosphatase↗
PubMed2003

[Analysis on the SARS-CoV genome of PUMC01 isolate].

OBJECTIVE: To perform variation and phylogenetics analysis on the SARS-CoV genome sequence (PUMC01) isolated in the Peking Union Medical College Hospital. METHODS: The cDNA library of SARS-CoV (PUMC01 isolate) was constructed by means of random-priming strategy. Random selected plasmid was sequenced and the genome sequence of SARS-CoV-PUMC01 was assembled by conventional methods (The Genebank Accession No. of SARS-CoV-PUMC01 is AY350750). The variation and phylogenetics analysis were performed by comparing the PUMC01 sequence with other SARS-CoV isolates. RESULTS: Ten variation sites were found by comparing PUMC01 isolate with Tor2 and Urbani isolates. In phylogenetic analysis of 18 SARS-CoV isolates, two classes were observed and there is different differential time between these two classes and the different isolates in each class. CONCLUSIONS: The evidence of phylogenetic analysis of different SARS-CoV isolates from different region is instructive for understanding the clinical relations between the different isolates and the transmission chain of SARS-CoV.

Amino Acid Sequence↗
PubMed2003

[Isolation and identification of SARS-coronavirus in nasal and throat swabs collected from clinically diagnosed SARS patients].

OBJECTIVE: To isolate and identify SARS-coronavirus in nasal and throat swabs collected from clinically diagnosed severe acute respiratory syndrome (SARS) patients. METHODS: Nasal and throat swab specimens were inoculated onto well of 24-well plate containing confluent monolayers of Vero and MRC-5 cells. Isolates were identified with serology, electron microscopy and genome sequence. RESULTS: One hundred and fifty-eight nasal and throat swabs specimens from 79 SARS patients in Peking Union Medical College Hospital between April and May, 2003 were cultured for SARS-coronavirus. Cytopathic effect (CPE) was found in three nasal swab specimens inoculated in Vero cells. Acute and convalescent phase serum specimens collected from SARS patients were found with seroconversions and/or a fourfold or greater rises in indirect fluorescence antibodies (IgG and IgM) titers when the 3 isolates (infected Vero cells) were used as antigen. Coronavirus was observed in the culture supernatant by negative-stain electron microscopy. Genome sequence confirmed the isolates were SARS-coronavirus. CONCLUSIONS: The 3 isolates from nasal and throat swabs samples collected from 79 clinically diagnosed SARS patients were SARS coronavirus.

Adolescent↗
PubMed2003

[Reliability of detecting SARS-CoV antibody for diagnosis of SARS].

OBJECTIVE: To discuss the reliability of SARS-CoV antibody detection for SARS diagnosis. METHODS: Using SARS-CoV ELISA kit to detect relevant antibody in fresh serum of healthy, fever, probable, and suspect cases. RESULTS: The positive rate is 0%, 40%, and 95% respectively in healthy, probable, and suspect cases. CONCLUSIONS: It is reliable to detect SARS-CoV antibody in late suspect patients, but there will be high false-positive result in ordinary fever cases.

Adolescent↗
PubMed2003

[In situ hybridization analysis of USF1 mRNA expression in odontoblasts].

OBJECTIVE: To detect and verify USF1 mRNA expression in odontoblasts. METHODS: T-USF1 clone prepared previously was used as template and the desired USF1 cDNA segment was amplified by PCR with specific primers. The segment was labeled with digoxin as a probe and in situ hybridization was performed on the mounting of odontoblasts. RESULTS: Evidently positive staining was shown in the cytoplasm of odontoblasts. CONCLUSION: We verified the expression of USF1 mRNA in odontoblasts for the first time and provided evidence for further research.

DNA-Binding Proteins↗
PubMed2003

[Molecular phylogeny of some species of the acridoidea based on 16S rDNA].

Based on the 16S rDNA of 8 species (belonging to 8 families of Acridoidea) from China and keyed to 8 relative species of Orthoptera from GenBank, the homologus sequences were compared. The used frequency of nucleotide was calculated and the molecular phylogenetic tree constructed by MEGA microsoft. In the 480 bp fragment of mitochondial 16S rDNA, A + T was about 70.7% and G + C only 29.3%. The sequence data revealed considerable variation in 188 nucleotide sites among the analyzed individuals from 8 different families. The variation rate of transversion was larger than or approach to transition. The results showed that the ranges of the 16S rDNA nucleotide divergence within species, among species of a genus, among genera of a family, and among the same family and suborder were 1.5%, 3.5%-3.6%, 4.8%-15.8% and 15.2%-25.6%, respectively. The members of the same genus and family were grouped together. The phylogenetic relationships of 8 families were Pyrgomorphidae-->Chrotogonidae-->Pamphagidae-->Oedipodidae-->Acrididae--> Arcypteridae-->Gomphoceridae-->Catantopidae. Pyrgomorphidae had closer relationships with Chrotogonidae as well as being the most ancestral group. Arcypteridae and Gomphoceridae were the sister groups and had closer relationships with most evolutionary Catantopidae. Tridactylidae was divided firstly as a suborder, which differs from the recent taxonomy distinctly. Haglidae (Tettigonoidea) and Gryllidae were grouped into suborder Ensifera, Tetrigidae and 8 families of Acridoidea were grouped into suborder Caelifera, as same as recent taxonomy.

Animals↗