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Biomedical subjects

Jun Yu

Publications and source records attributed to Jun Yu.

At least 127 records · Page 7Linked to original sources
PubMed2004

A new role for Nogo as a regulator of vascular remodeling.

Although Nogo-A has been identified in the central nervous system as an inhibitor of axonal regeneration, the peripheral roles of Nogo isoforms remain virtually unknown. Here, using a proteomic analysis to identify proteins enriched in caveolae and/or lipid rafts (CEM/LR), we show that Nogo-B is highly expressed in cultured endothelial and smooth muscle cells, as well as in intact blood vessels. The N terminus of Nogo-B promotes the migration of endothelial cells but inhibits the migration of vascular smooth muscle (VSM) cells, processes necessary for vascular remodeling. Vascular injury in Nogo-A/B-deficient mice promotes exaggerated neointimal proliferation, and adenoviral-mediated gene transfer of Nogo-B rescues the abnormal vascular expansion in those knockout mice. Our discovery that Nogo-B is a regulator of vascular homeostasis and remodeling broadens the functional scope of this family of proteins.

Animals↗
PubMed2004

Effects of cholesterol on proliferation and functional protein expression in rabbit bile duct fibroblasts.

AIM: To investigate the effect of cholesterol (Ch) on the growth and functional protein expression of rabbit bile duct fibroblasts. METHODS: The cultured bile duct fibroblasts were divided randomly into two groups: the control group and the experiment group (fibroblasts were incubated respectively with 0.6 g/L Ch for 12, 24, 36 and 48 h). The growth and DNA synthesis of bile duct fibroblasts were measured by the means of (3)H-TdR incorporation. The total protein content of fibroblast was measured by BSA protein assay reagent kit, then the expression of alpha-actin was analyzed semi-quantitatively by Western blot. RESULTS: After treatment with 0.6 g/L Ch for 12, 24, 36 and 48 h, the values of (3)H-TdR incorporation of bile duct fibroblasts were respectively 3.1+/-0.39, 3.8+/-0.37, 4.6+/-0.48 and 5.2+/-0.56 mBq/cell, and the values of the corresponding control groups were 3.0+/-0.33, 3.2+/-0.39, 3.7+/-0.49 and 4.3+/-0.43 mBq/cell. After comparing the values of experiment groups and their corresponding control groups, it was found that the (3)H-TdR incorporation of bile duct fibroblasts after treatment with 0.6 g/L Ch for 24, 36 and 48 h were significantly increased (P<0.05, P<0.01, P<0.01), while the (3)H-TdR incorporation of 12-h group was not different statistically from its control group. Ch had no obvious effect on the total protein content of fibroblasts. After incubated with 0.6 g/L Ch for 12, 24, 36 and 48 h, the total protein content of each experiment group was not altered markedly compared with its corresponding control group. The values of experiment groups were 0.246+/-0.051, 0.280+/-0.049, 0.263+/-0.044 and 0.275+/-0.056 ng/cell, and those of corresponding control groups were 0.253+/-0.048, 0.270+/-0.042, 0.258+/-0.050 and 0.270+/-0.045 ng/cell. Western blot analysis revealed that the alpha-actin expression in fibroblasts affected by Ch for 12 and 24 h was not markedly changed compared with their corresponding control groups (P>0.05), the values of total gray scale of 12- and 24-h groups were 1748+/-185 and 1756+/-173, respectively. But after stimulation with Ch for 36 h, the total gray scale of fibroblasts (1923+/-204) was significantly higher than that of control group (1734+/-197). When the time of Ch treatment was lengthened to 48 h, the alpha-actin expression was markedly elevated, the total gray scale was 2 189+/-231 (P<0.01 vs control group). CONCLUSION: Moderately concentrated Ch can promote the proliferation of bile duct fibroblasts at early stage. With the prolongation of Ch treatment, the alpha-actin expression of fibroblasts was also increased, but the hypertrophy of fibroblasts was not observed.

Actins↗
PubMed2004

[Vasorelaxing effect of idoxifene on human internal mammary arteries].

The purpose of this study was to investigate the vasorelaxing effect and mechanism of idoxifene (a new estrogen receptor modulator) on human internal mammary artery (HIMA). HIMA segments were harvested from men during coronary artery bypass grafting surgery. Patients with diabetes mellitus, hypercholesterolemia, hypertension, or smoking habit were excluded. The vasorelaxing effect of idoxifene on artery rings from HIMA with and without endothelium was measured by means of perfusion in vitro. Cumulative dose-response to idoxifene in the range of 0.01-10 micromol/L was observed in the presence and absence of NO synthase inhibitor L-NAME. It was also studied whether the vasodilation effect of idoxifene on HIMA was blocked by methylene blue (MB), an inhibitor of guanylate cyclase (GC). The results obtained from idoxifene were compared with those from 17beta-estradiol (E(2)). It was found that idoxifene caused a concentration-dependent relaxation on HIMA. The dose range was from 0.03 micromol/L (minimal vasodilatory concentration) to 3 mmol/L (maximal vasodilatory concentration). It was also found that the vasorelaxation effect of idoxifene on HIMA was dependent on endothelium. E(2) (0.1-100 micromol/L) also resulted in an endothelium-dependent vasorelaxation, but the vessels were 15-fold less sensitive to E(2) than to idoxifene in their vasorelaxation responses. The EC(50) for E(2) was 4.65+/-0.34 micromol/L, compared with 0.32+/-0.02 micromol/L for idoxifene. The mean maximal vasodilatory value of E(2) was 88.3+/-5.7%, compared with 88.6+/-7.2% for idoxifene. Pretreatment with L-NAME (100micromol/L) abolished idoxifene-induced vasodilation virtually by blocking nitric oxide production. The vasorelaxing effect of idoxifene disappeared in the presence of MB (10 micromol/L). These findings demonstrate that idoxifene results in an endothelium-dependent vasorelaxation of HIMA, like estrogen. The effect of idoxifene is more potent than that of traditional estrogen, and is possibly mediated by NO-GC-cGMP pathway.

Estrogen Antagonists↗
PubMed2004

Genes controlling seed dormancy and pre-harvest sprouting in a rice-wheat-barley comparison.

Pre-harvest sprouting results in significant economic loss for the grain industry around the world. Lack of adequate seed dormancy is the major reason for pre-harvest sprouting in the field under wet weather conditions. Although this trait is governed by multiple genes it is also highly heritable. A major QTL controlling both pre-harvest sprouting and seed dormancy has been identified on the long arm of barley chromosome 5H, and it explains over 70% of the phenotypic variation. Comparative genomics approaches among barley, wheat and rice were used to identify candidate gene(s) controlling seed dormancy and hence one aspect of pre-harvest sprouting. The barley seed dormancy/pre-harvest sprouting QTL was located in a region that showed good synteny with the terminal end of the long arm of rice chromosome 3. The rice DNA sequences were annotated and a gene encoding GA20-oxidase was identified as a candidate gene controlling the seed dormancy/pre-harvest sprouting QTL on 5HL. This chromosomal region also shared synteny with the telomere region of wheat chromosome 4AL, but was located outside of the QTL reported for seed dormancy in wheat. The wheat chromosome 4AL QTL region for seed dormancy was syntenic to both rice chromosome 3 and 11. In both cases, corresponding QTLs for seed dormancy have been mapped in rice.

Amino Acid Sequence↗
PubMed2004

BGI-RIS: an integrated information resource and comparative analysis workbench for rice genomics.

Rice is a major food staple for the world's population and serves as a model species in cereal genome research. The Beijing Genomics Institute (BGI) has long been devoting itself to sequencing, information analysis and biological research of the rice and other crop genomes. In order to facilitate the application of the rice genomic information and to provide a foundation for functional and evolutionary studies of other important cereal crops, we implemented our Rice Information System (BGI-RIS), the most up-to-date integrated information resource as well as a workbench for comparative genomic analysis. In addition to comprehensive data from Oryza sativa L. ssp. indica sequenced by BGI, BGI-RIS also hosts carefully curated genome information from Oryza sativa L. ssp. japonica and EST sequences available from other cereal crops. In this resource, sequence contigs of indica (93-11) have been further assembled into Mbp-sized scaffolds and anchored onto the rice chromosomes referenced to physical/genetic markers, cDNAs and BAC-end sequences. We have annotated the rice genomes for gene content, repetitive elements, gene duplications (tandem and segmental) and single nucleotide polymorphisms between rice subspecies. Designed as a basic platform, BGI-RIS presents the sequenced genomes and related information in systematic and graphical ways for the convenience of in-depth comparative studies (http://rise.genomics.org.cn/).

China↗
PubMed2004

EST-based analysis of gene expression in the porcine brain.

Since pig is an important livestock species worldwide, its gene expression has been investigated intensively, but rarely in brain. In order to study gene expression profiles in the pig central nervous system, we sequenced and analyzed 43,122 high-quality 5' end expressed sequence tags (ESTs) from porcine cerebellum, cortex cerebrum, and brain stem cDNA libraries, involving several different prenatal and postnatal developmental stages. The initial ESTs were assembled into 16,101 clusters and compared to protein and nucleic acid databases in GenBank. Of these sequences, 30.6% clusters matched protein databases and represented function known sequences; 75.1% had significant hits to nucleic acid databases and partial represented known function; 73.3% matched known porcine ESTs; and 21.5% had no matches to any known sequences in GenBank. We used the categories defined by the Gene Ontology to survey gene expression in the porcine brain.

Animals↗
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

Structure-based preliminary analysis of immunity and virulence of SARS coronavirus.

The research on SARS-associated coronavirus (SARS-CoV) has not stopped since its discovery, but the pathogenesis of SARS is still unclear. To explore the possible molecular mechanisms of the invasion and virulence of SARS-CoV, we investigated the structural basis of the viral proteins using computational biology. Forty-five motifs relating to superantigens, toxins and other bioactive molecules were detected in the proteins of SARS-CoV. The results showed that the distribution of the motifs varied in different proteins. Enzyme-like motifs were located in the R protein, while ICAM- 1-like and toxin-like molecules were located in the spike, envelop, nucleocapsid, PUP1, PUP 2 and PUP 4 proteins. Comparison of SARS-CoV with other viruses (OC43, PEDV, HRSV, HHerpV and HAdenoV) showed that each group of motifs was different for each type of virus. Data suggest that the proteins of SARS-CoV with toxic motifs might play crucial roles in targeting host cells and interfering with the immune system. This study provides new information for drug and vaccine design, as well as therapeutic strategies against SARS.

Amino Acid Motifs↗
PubMed2004

Distribution of espI among clinical enterohaemorrhagic and enteropathogenic Escherichia coli isolates.

Enterohaemorrhagic (EHEC) and enteropathogenic (EPEC) Escherichia coli are important diarrhoeagenic pathogens; infection is dependent on translocation of a number of type III effector proteins. Until recently all the known effectors were encoded on the LEE pathogenicity island, which also encodes the adhesin intimin and the type III secretion apparatus. Recently, a novel non-LEE effector protein, EspI/NleA, which is required for full virulence in vivo and is encoded on a prophage, was identified. The aim of this study was to determine the distribution of espI among clinical EHEC and EPEC isolates. espI was detected in 86 % and 53 % of LEE+ EHEC and EPEC strains, respectively. Moreover, the espI gene was more commonly found in patients suffering from a more severe disease.

Adhesins, Bacterial↗
PubMed2004

The role of the Shigella flexneri yihE gene in LPS synthesis and virulence.

Previously, the authors have shown that inactivation of Shigella flexneri yihE, a gene of unknown function upstream of dsbA, which encodes a periplasmic disulphide catalyst, results in a global change of gene expression. Among the severely down-regulated genes are galETKM, suggesting that the yihE mutant, Sh54, may inefficiently produce the UDP-glucose and UDP-galactose required for LPS synthesis. This paper demonstrates that LPS synthesis in Sh54 is impaired. As a result, Sh54 is unable to polymerize host cell actin, due to aberrant localization of IcsA, or to cause keratoconjunctivitis in guinea pigs. Furthermore, Sh54 is more sensitive to some antimicrobial agents, and exhibits epithelial cytotoxicity characteristic of neither wild-type nor dsbA mutants. Supplying galETK in trans restores LPS synthesis and corrects all the defects. Hence, it is clear that the Shigella yihE gene is important not only in regulating global gene expression, as shown previously, but also in virulence through LPS synthesis via regulating the expression of the galETK operon.

Animals↗
PubMed2004

Improved maximum frequency estimation with application to instantaneous mean frequency estimation of surface electromyography.

The purpose of this study was to improve the maximum-frequency estimation. Three methods to estimate the maximum frequency of a bandlimited signal with additive white noise were compared. Two existing methods, the threshold-crossing method (TCM) and the hybrid method, were modified for time-frequency representations. A novel approach, the running-block threshold method (RBTM), was introduced. Based on calculation of detection probability (sensitivity) the RBTM improved the maximum-frequency estimate as compared with the TCM. The maximum-frequency estimation methods were also used to determine the integration interval for instantaneous mean-frequency (IMNF) estimation from synthesized surface electromyography containing white noise. Results showed that the IMNF estimate was improved by using any of the three methods and that the RBTM gave the best IMNF estimate.

Action Potentials↗
PubMed2004

Lack of major involvement of human uroplakin genes in vesicoureteral reflux: implications for disease heterogeneity.

BACKGROUND: Primary vesicoureteral reflux (VUR) is a hereditary disorder characterized by the retrograde flow of urine into the ureters and kidneys. It affects about 1% of the young children and is thus one of the most common hereditary diseases. Its associated nephropathy is an important cause of end-stage renal failure in children and adults. Recent studies indicate that genetic ablation of mouse uroplakin (UP) III gene, which encodes a 47 kD urothelial-specific integral membrane protein forming urothelial plaques, causes VUR and hydronephrosis. METHODS: To begin to determine whether mutations in UP genes might play a role in human VUR, we genotyped all four UP genes in 76 patients with radiologically proven primary VUR by polymerase chain reaction (PCR) amplification and sequencing of all their exons plus 50 to 150 bp of flanking intronic sequences. RESULTS: Eighteen single nucleotide polymorphisms (SNPs) were identified, seven of which were missense, with no truncation or frame shift mutations. Since healthy relatives of the VUR probands are not reliable negative controls for VUR, we used a population of 90 race-matched, healthy individuals, unrelated to the VUR patients, as controls to perform an association study. Most of the SNPs were not found to be significantly associated with VUR. However, SNP1 of UP Ia gene affecting a C to T conversion and an Ala7Val change, and SNP7 of UP III affecting a C to G conversion and a Pro154Ala change, were marginally associated with VUR (both P= 0.08). Studies of additional cases yielded a second set of data that, in combination with the first set, confirmed a weak association of UP III SNP7 in VUR (P= 0.036 adjusted for both subsets of cases vs. controls). CONCLUSION: Such a weak association and the lack of families with simple dominant Mendelian inheritance suggest that missense changes of uroplakin genes cannot play a dominant role in causing VUR in humans, although they may be weak risk factors contributing to a complex polygenic disease. The fact that no truncation or frame shift mutations have been found in any of the VUR patients, coupled with our recent finding that some breeding pairs of UP III knockout mice yield litters that show not only VUR, but also severe hydronephrosis and neonatal death, raises the possibility that major uroplakin mutations could be embryonically or postnatally lethal in humans.

Alanine↗
PubMed2004

Noninvasive optical imaging method to evaluate postantibiotic effects on biofilm infection in vivo.

Eradication of Staphylococcus aureus biofilms after rifampin treatment was tested in a mouse model of device-related infection by using biophotonic imaging. Following treatment, the bioluminescent signals decreased to undetectable levels, irrespective of the age of the biofilm. After the final treatment, the signals rebounded in a time-dependent manner and reached those for the untreated mice. Readministration of rifampin was unsuccessful in eradicating reestablished infections, with the rifampin MICs for such bacteria being increased and with the bacteria having point mutations in the rpoB gene.

Animals↗
PubMed2004

Identification of a novel Citrobacter rodentium type III secreted protein, EspI, and roles of this and other secreted proteins in infection.

Citrobacter rodentium is a member of a group of pathogens that colonize the lumen of the host gastrointestinal tract via attaching and effacing (A/E) lesion formation. C. rodentium, which causes transmissible colonic hyperplasia in mice, is used as an in vivo model system for the clinically significant A/E pathogens enterohemorrhagic and enteropathogenic Escherichia coli. These bacteria all contain a pathogenicity island called the locus of enterocyte effacement (LEE), which encodes a type III secretion system that is designed to deliver effector proteins into eukaryotic host cells. These effectors are involved in the subversion of host eukaryotic cell functions to the benefit of the bacterium. In this study we used mutant strains to determine the effects of the C. rodentium LEE-encoded effectors EspF, EspG, EspH, and Map on virulence in the mouse model. In addition, we identified a novel secreted protein, EspI encoded outside the LEE, whose secretion is also dependent on a functional type III secretion system. Mutant strains with each of the effectors investigated were found to be outcompeted by wild-type bacteria in mixed-infection experiments in vivo, although the effects of EspF and EspH were only subtle. In single-infection experiments, we found that EspF, EspG, and EspH are not required for efficient colonization of the mouse colon or for the production of hyperplasia. In contrast, strains producing EspI and Map had significant colonization defects and resulted in dramatically reduced levels of hyperplasia, and they exhibited very different growth dynamics in mice than the wild-type strain exhibited.

Amino Acid Sequence↗
PubMed2004

DNA microarray analysis of genome dynamics in Yersinia pestis: insights into bacterial genome microevolution and niche adaptation.

Genomics research provides an unprecedented opportunity for us to probe into the pathogenicity and evolution of the world's most deadly pathogenic bacterium, Yersinia pestis, in minute detail. In our present work, extensive microarray analysis in conjunction with PCR validation revealed that there are considerable genome dynamics, due to gene acquisition and loss, in natural populations of Y. pestis. We established a genomotyping system to group homologous isolates of Y. pestis, based on profiling or gene acquisition and loss in their genomes, and then drew an outline of parallel microevolution of the Y. pestis genome. The acquisition of a number of genomic islands and plasmids most likely induced Y. pestis to evolve rapidly from Yersinia pseudotuberculosis to a new, deadly pathogen. Horizontal gene acquisition also plays a key role in the dramatic evolutionary segregation of Y. pestis lineages (biovars and genomovars). In contrast to selective genome expansion by gene acquisition, genome reduction occurs in Y. pestis through the loss of DNA regions. We also theorized about the links between niche adaptation and genome microevolution. The transmission, colonization, and expansion of Y. pestis in the natural foci of endemic plague are parallel and directional and involve gradual adaptation to the complex of interactions between the environment, the hosts, and the pathogen itself. These adaptations are based on the natural selections against the accumulation of genetic changes within genome. Our data strongly support that the modern plague originated from Yunnan Province in China, due to the arising of biovar orientalis from biovar antiqua rather than mediaevalis.

Adaptation, Physiological↗
PubMed2004

Down-regulation of C-type natriuretic peptide receptor by vasonatrin peptide in cardiac myocytes and fibroblasts.

AIM: To investigate the regulatory effects of vasonatrin peptide (VNP) on the expression of C-type natriuretic peptide receptor (NPR-C) in cultured neonatal rat cardiac myocytes and fibroblasts. METHODS: Quantitative RT-PCR was undertaken to evaluate the levels of NPR-C mRNA and radioimmunoassay was used to determine the formation of intracellular cGMP. RESULTS: Twenty-four hours hypoxic exposure increased the level of NPR-C mRNA in cardiomyocytes, while did not alter the expression of NPR-C in cardiac fibroblasts. VNP (10(-8)-10(-6) mol/L) reduced the levels of NPR-C mRNA in cardiac myocytes induced by hypoxia in a concentration-dependent manner, and with high concentration (10(-6) mol/L) also decreased the expression of NPR-C in cardiac fibroblasts and air-control cardiac myocytes. The inhibitory effects of VNP on the expression of NPR-C was mimicked by 8-bromo-cGMP 10(-6) mol/L (a membrane permeable analog of cGMP). VNP (10(-8)-10(-6) mol/L) increased the formation of intracellular guanosine-3',5'-cyclic monophosphate (cGMP) in both cardiac myocytes and fibroblasts. HS-142-1, the particulate guanylyl cyclase-coupled receptor antagonist, partially abrogated the above effects of VNP. CONCLUSION: Hypoxic exposure for 24 h up-regulated the expression of NPR-C in cultured neonatal rat cardiac myocytes. VNP decreased the expression of NPR-C in cardiac myocytes and fibroblasts under both air-control and hypoxic condition, which was at least partially mediated by guanylate cyclase linked natriuretic peptide receptors through increasing the intracellular cGMP.

Animals↗
PubMed2004

Orthotopic liver transplantation for patients with hepatocellular carcinoma complicated by portal vein tumor thrombi.

BACKGROUND: Orthotopic liver transplantation (OLT) has been the valuable treatment of choice for patients with hepatocellular carcinoma (HCC). As the number of patients with portal vein tumor thrombi (PVTT) increases, most transplant centers become suspicious of the exact effect of the operation which has been accepted as a radical method. This study was designed to evaluate the clinical effects of OLT for patients with HCC associated with PVTT. METHODS: The follow-up of 24 patients with HCC complicated by PVTT who had received OLT (transplant group) from January 1999 to March 2003 was compared to that of 27 patients undergoing routine hepatic resection (resection group) and 59 patients without surgical treatment (non-surgical group). RESULTS: The perioperative mortality was zero for the transplant group. The 6-month, 1-year, and 2-year overall survival rates were 66.7%, 29.5% and 23.6% for the transplant group, 33.3%, 22.2% and 14.8% for the resection group (P=0.0335), and 42.1%, 24.4% and 4.1% for the non-surgical group, respectively (P=0.0316). The tumor free survival rates of recipients at 6-month, 1-year, and 2-year were 51.5%, 23.2% and zero, respectively. During the period of follow-up, the overall post-transplant intrahepatic recurrence or extrahepatic metastasis rate was 66.7% for the transplant group. CONCLUSION: OLT is an effective but palliative treatment modality for patients with HCC associated with PVTT followed by a prolonged survival but a poor tumor free survival rate.

Budd-Chiari Syndrome↗