Biomedical subjects

Y H Sun

Publications and source records attributed to Y H Sun.

At least 19 recordsLinked to original sources

PubMed2005

New genotype of avian influenza H5N1 viruses isolated from tree sparrows in China.

The 2004 outbreaks of highly pathogenic avian influenza H5N1 disease in China led to a great poultry loss and society attention. A survey of avian influenza viruses was conducted on tree sparrows (Passer montanus) collected in China in 2004. Four viruses were isolated from free-living tree sparrows. The results of the whole-genome analysis indicated that an H5N1 virus with a new genotype is circulating among tree sparrows. The hemagglutinin and neuraminidase genes of the new genotype were derived from Gs/Gd/96-like viruses and the nuclear protein gene descended from the 2001 genotype A H5N1 viruses, while the other inner genes originated from an unknown influenza virus. In experimental infection, all four viruses were highly pathogenic to chickens but not pathogenic to ducks or mice. The four tree sparrow viruses were different from the 2003 tree sparrow strain (genotype Z) in Hong Kong. The results suggested that H5N1 viruses might be distributed widely in tree sparrows.

Animals↗

PubMed2003

Characterization of cDNA encoding immunoglobulin light chain of the mandarin fish (Siniperca chuatsi).

Immunoglobulin light chain cDNA sequences of a perciform fish, the mandarin fish Siniperca chuatsi were amplified from head kidney mRNA by reverse transcription (RT)-PCR and RACE methods using degenerated primer and gene specific ones. In cDNA sequences of the VL region, nucleotide exchanges were present mainly within CDRs, although a lesser degree of variability was also found in FRs. Moreover, the length of CDR1 and CDR3 in the mandarin fish is shorter than in most other fish species. In the middle of S. chuatsi CL region, a microsatellite sequence (AGC)(6-8) was found, which is also present in another perciform species, the spotted wolffish (Anarhichas minor). The comparison of amino acid sequence of the mandarin fish CL domain with those of other vertebrates showed the highest degree of similarity of 94.5% to the spotted wolffish, while the similarity with rainbow trout (Oncorhynchus mykiss) Ig L1 (62.7%) and channel catfish (Ictalurus punctatus) Ig LG (55.9%) isotypes is also higher. However, there is only 50% identity in the VL regions between the mandarin fish and the wolffish. The sequence similarity of the mandarin fish CL domain with those of higher vertebrate did not readily allow it to be classified as kappa or lambda isotype. The phylogenetic analyses also demonstrated that the CL genes of the mandarin fish and most other teleost fish cluster as a separate branch out of the mammal kappa and lambda branches.

Amino Acid Sequence↗

PubMed2001

Blends of stearyl poly(ethylene oxide) coupling-polymer in chitosan as coating materials for polyurethane intravascular catheters.

To optimize the surface biocompatibility of the intravascular catheter, an amphiphilic coupling-polymer of stearyl poly (ethylene oxide) -co- 4,4'-methylene diphenyl diisocyanate-co- stearyl poly (ethylene oxide), for short MSPEO, was specially designed as the surface modifying additive (SMA). The blend of MSPEO in chitosan was coated on the outer wall of the catheters by the dip-coating method. The surface analysis was carried out by ATR-FTIR and contact angle measurements. The surface enrichment of MSPEO was confirmed. On the water interface, the larger the molecular weight of PEO was, the higher the surface enrichment. While on air interface, the case was the contrary. Three kinds of static test of clotting time, plasma recalcification time (PRT), prothrombin time (PT), and thrombin time (TT), as well as the static platelet adhesion experiment were carried out. The results indicated that the coated surface could resist the clotting effectively. In order to test the blood-compatibility of the coated catheters under a shear of blood flow, the dynamic experiment was performed through a closed-loop tubular system with the shear rate of 1500 s(-1). The results of blood regular testing at six different times (0, 5,10, 20, 30, and 60 min) indicated that the biocompatibility of the coating was nearly ideal. Finally, the SMA-MSPEO was proved to be non-chronic-toxic by animal experiments with rats and suitable as a coating material for clinical use.

Animals↗

PubMed2001

Intraurethral brachytherapy for prevention of recurrent urethral stricture after internal urethrotomy or transurethral resection of scar.

BACKGROUND PURPOSE: Restricture after internal urethrotomy is the major limitation to the long-term success of the procedure. The objective of this study was to evaluate the effect of intraurethral brachytherapy after internal urethrotomy or transurethral scar resection on recurrent urethral stricture. PATIENTS AND METHODS: From January 1998 to June 1999, catheter-based intraurethral brachytherapy with 192-iridium was performed in 17 patients with recurrent urethral stricture to prevent restricture after internal urethrotomy or transurethral resection of scar. The radiation was repeated within 3 days after surgery to reach a total dosage of 1000 to 1500 cGy. RESULTS: During the follow-up (range 14-27 months; mean 20 months), two patients had dysuria, including one patient with an atonic detrusor muscle. The other patient needed self-dilation. Fifteen patients presented normal voiding. The stricture recurred 3 months later in only one patient, so the restricture rate is 7%. No significant complication was observed associated with brachytherapy during the follow-up. CONCLUSION: Intraurethral brachytherapy after internal urethrotomy or transurethral resection of scar is a safe and effective treatment for recurrent urethral strictures.

Adolescent↗

PubMed2001

Compression of interventricular septum during right ventricular pressure loading.

The interventricular septum, which flattens and inverts in conditions such as pulmonary hypertension, is considered by many to be an unstressed membrane, in that its position is assumed to be determined solely by the transseptal pressure gradient. A two-dimensional finite element model was developed to investigate whether compression and bending moments (behavior incompatible with a membrane) exist in the septum during diastole under abnormal loading, i.e., pulmonary artery (PA) constriction. Hemodynamic and echocardiographic data were obtained in six open-chest anesthetized dogs. For both control and PA constriction, the measured left ventricular and right ventricular pressures were applied to a residually stressed mesh. Adjustments were made to the stiffness and end-bending moments until the deformed and loaded residually stressed mesh matched the observed configuration of the septum. During PA constriction, end-bending moments were required to obtain satisfactory matches but not during control. Furthermore, substantial circumferential compressive stresses developed during PA constriction. Such stresses might impede septal blood flow and provoke the unexplained ischemia observed in some conditions characterized by abnormal septal motion.

Animals↗

PubMed2001

Identification of bacterial genes required for in-vivo survival.

Genetic approaches used for in-vivo studies of bacterial pathogenesis are providing insights into how bacteria disrupt host defences and exploit host molecules for their own advantage. Signature tagged mutagenesis (STM) provides a means of identifying the genes involved in the process of infection, particularly those genes that are important for bacterial proliferation in-vivo. In this review, the application of STM to the understanding of bacterial pathogenesis and findings from work on three human pathogens, Salmonella typhimurium, Mycobacterium tuberculosis and Neisseria meningitidis, are discussed. The next challenge is to understand how these and other genes influence the infective process at the molecular and cellular levels and to design novel interventions to block the progression of disease.

Bacteria↗

PubMed2001

Effect of inhaled budesonide on bronchial hyperresponsiveness in adolescents with clinical remission of asthma.

STUDY OBJECTIVE: Many children with asthma go into long-term clinical remission at adolescence, but bronchial hyperresponsiveness (BHR) persists in some of these subjects. The regular use of inhaled corticosteroids improves BHR in patients with symptomatic asthma. The aim of this study was to determine whether BHR in adolescents with asthma remission could be reduced by prolonged treatment with inhaled corticosteroids. DESIGN: A randomized, double-blind, placebo-controlled, parallel study. PATIENTS: Thirty-seven adolescents with BHR and long-term remission of their asthma (neither symptoms nor any medication use during the previous 2 years). INTERVENTION: Subjects received inhaled budesonide (two 200-microg puffs bid; budesonide group, n = 19) or identical placebo (placebo group, n = 18) for 9 months. A separate group of patients with symptomatic asthma (symptomatic group, n = 19), using the same regimen of budesonide, was also studied. MEASUREMENTS AND RESULTS: The provocative concentration of methacholine producing a 20% fall in FEV(1) (PC(20)) was measured before and every 3 months during treatment. There was no significant difference among the three groups for the baseline PC(20). In neither the placebo nor the budesonide group did the geometric mean of PC(20) change significantly over the 9-month period. In contrast, a significant increase in PC(20) was noted in the symptomatic group as a result of the budesonide treatment. CONCLUSION: Our data have shown that budesonide inhaled regularly for 9 months did not cause a significant improvement in the BHR of adolescents with long-term asthma remission. This suggests that the mechanism underlying BHR in this clinical setting may be different from that in symptomatic asthma.

Administration, Inhalation↗

PubMed2001

Functional genomics and cell wall biosynthesis in loblolly pine.

Loblolly pine (Pinus taeda L.) is the most widely planted tree species in the USA and an important tree in commercial forestry world-wide. The large genome size and long generation time of this species present obstacles to both breeding and molecular genetic analysis. Gene discovery by partial DNA sequence determination of cDNA clones is an effective means of building a knowledge base for molecular investigations of mechanisms governing aspects of pine growth and development, including the commercially relevant properties of secondary cell walls in wood. Microarray experiments utilizing pine cDNA clones can be used to gain additional information about the potential roles of expressed genes in wood formation. Different methods have been used to analyze data from first-generation pine microarrays, with differing degrees of success. Disparities in predictions of differential gene expression between cDNA sequencing experiments and microarray experiments arise from differences in the nature of the respective analyses, but both approaches provide lists of candidate genes which should be further investigated for potential roles in cell wall formation in differentiating pine secondary xylem. Some of these genes seem to be specific to pine, while others also occur in model plants such as Arabidopsis, where they could be more efficiently investigated.

Arabidopsis↗

PubMed2001

[Changes in cyclin expression during proliferation and differentiation of CD34(+) cells derived from fetal liver induced by thrombopoietin].

In order to elucidate the intrinsic mechanism underlying proliferation and differentiation of megakaryocytes during ontogenesis, CD34(+) cells were isolated from human fetal liver (FL) with a high-gradient magnetic sorting system (MACS) and were incubated in liquid suspension with 50 and 100 ng/ml of thrombopoietin (TPO) and in MegaCult(Tm) -C semi-solid culture system with 0, 12.5, 25, 50, 100, and 200 ng/ml of TPO. The cell number, colony number of CFU-Mk, platelet-associated antigen phenotype, and DNA ploidy of CD41(+) cells were examined from d 0 to d 12 in culture. The expression patterns of cyclins B1, D1, and D3 were also analyzed by using immunoblot and flow cytometry. TPO stimulated proliferation of CD34(+) cells of FL from 1 x 10(5)/ml to 13.12 +/-4.06 10(5)/ml with 95% of CD41a(+) cells and 3% of CD34(+) cells after 12 d of culture. Most of the megakaryocytes (MKs) derived from FL were in 2 N ploidy class, and few in 4 N ploidy class, but no megakaryocytes ploidy class was higher than 4 N. The effect of TPO on the formation of CFU-Mk colonies from FL derived CD34(+) cells is shown in a dose-response curve. The expression of cyclin B1 increased progressively and the high level of cyclin B1 was maintained in FL CD34(+) cells induced by TPO during 12 d of culture. A high level of cyclin B1 appeared on FL derived MKs of G1 phase at d 12. The expression of cy-of cyclins D1 and D3 gradually increased in FL CD34(+) cells, which was induced by TPO during the initial 6-day incubation. Afterwards, the level of cyclins D1 and D3 decreased progressively, particularly in MKs which were in G2+M phases. These data suggest that (1) TPO induced proliferation and differentiation of FL derived CD34(+) cells through upregulation of cyclin B1 in G2+M phases and cyclins D1 and D3 in all phases of cell cycle, and (2) Continuing high level of cyclin B1 and decreases of cyclins D1 and cyclin D3 on MKs in G2+M phases may contribute to a retardation of MK endoreduplication.

Antigens, CD34↗

PubMed2000

Direct interaction of two homeoproteins, homothorax and extradenticle, is essential for EXD nuclear localization and function.

The Drosophila Homothorax (HTH) and Extradenticle (EXD) are two homeoproteins required in a number of developmental processes. EXD can function as a cofactor to Hox proteins. Its nuclear localization is dependent on HTH. In this study we present evidence of in vivo physical interaction between HTH and EXD, mediated primarily through an evolutionarily conserved MH domain in HTH. This interaction is essential for the mutual stabilization of both proteins, for EXD nuclear localization, and for the cooperative DNA binding of the EXD-HTH heterodimer. Some in vivo functions require both EXD and HTH in the nucleus, suggesting that the EXD-HTH complex may function as a transcriptional regulator.

Amino Acid Sequence↗

PubMed2000

CD34+ cells derived from fetal liver contained a high proportion of immature megakaryocytic progenitor cells.

Endoreplication and maturation of the megakaryocyte (MK) may be retarded or delayed during ontogenesis. In this study, CD34+ cells were isolated from both human fetal liver and adult bone marrow and incubated with thrombopoietin (TPO). The cell number, morphological characteristics, platelet-associated antigen phenotype, maturation stage and DNA ploidy of CD41+ cells were examined from day 0 to day 12 in culture. 1) TPO stimulated the proliferation of fetal liver (FL)-derived CD34+ cells with a mean 73.14-fold increase of CD41+ cells after 12 d in culture. Adult BM-derived CD34+ cells increased only slightly, with a mean 8.18-fold increase of CD41+ cells. 2) Although the membrane phenotype of both FL CD34+-derived MKs and BM CD34+ -derived MKs analyzed with CD41a, CD42a, CD61 and CD34 were similar, all FL CD34+-derived MKs were in maturation stage I and II and in low ploidy (<4N) class. By comparison, BM CD34+ MKs possessed 15% MKs in maturation stage III and IV and with 23% MKs in high ploidy class ( > 4N). 3) Most of cultured FL-derived CD34+ cells did not have a well developed demarcation system (DM) and numerous alpha-granules after 12 d incubation. von Willebrand factor (vWF) appeared earlier on the cultured BM-derived CD34+ cells than on FL-derived CD34+ cells. 4) The expression of both cyclin E and cyclin B1 progressively increased in FL CD34+ cells induced by TPO during 12 d in culture. 5) The expression of cyclin D1 gradually decreased in FL CD34+ cells induced by TPO over 12 d incubation. 6) Immunocytochemical analysis showed that cyclin D3 was detected only in cytoplasm of cultured FL-derived CD34+ cells, whereas in both cytoplasm and nuclei of cultured BM-derived CD34+ cells. These data suggest that FL-derived CD34+ cells contain a high proportion of immature megakaryocytic progenitor cells. It further suggests that TPO can push these progenitor cells into proliferation by upregulating the expression of cyclins B1 and E, and drive a high proportion of cells into megakaryocytic lineage.

Adult↗

PubMed2000

Functional genomics of Neisseria meningitidis pathogenesis.

The pathogenic bacterium Neisseria meningitidis is an important cause of septicemia and meningitis, especially in childhood. The establishment and maintenance of bacteremic infection is a pre-requisite for all the pathological sequelae of meningococcal infection. To further understand the genetic basis of this essential step in pathogenesis, we analyzed a library of 2,850 insertional mutants of N. meningitidis for their capacity to cause systemic infection in an infant rat model. The library was constructed by in vitro modification of Neisseria genomic DNA with the purified components of Tn10 transposition. We identified 73 genes in the N. meningitidis genome that are essential for bacteremic disease. Eight insertions were in genes encoding known pathogenicity factors. Involvement of the remaining 65 genes in meningocoocal pathogenesis has not been demonstrated previously, and the identification of these genes provides insights into the pathogenic mechanisms that underlie meningococcal infection. Our results provide a genome-wide analysis of the attributes of N. meningitidis required for disseminated infection, and may lead to new interventions to prevent and treat meningococcal infection.

Animals↗

PubMed2000

Embryonic and genetic manipulation in fish.

Fishes, the biggest and most diverse community in vertebrates are good experimental models for studies of cell and developmental biology by many favorable characteristics. Nuclear transplantation in fish has been thoroughly studied in China since 1960s. Fish nuclei of embryonic cells from different genera were transplanted into enucleated eggs generating nucleo-cytoplasmic hybrids of adults. Most importantly, nuclei of cultured goldfish kidney cells had been reprogrammed in enucleated eggs to support embryogenesis and ontogenesis of a fertile fish. This was the first case of cloned fish with somatic cells. Based on the technique of microinjection, recombinant MThGH gene has been transferred into fish eggs and the first batch of transgenic fish were produced in 1984. The behavior of foreign gene was characterized and the onset of the foreign gene replication occurred between the blastula to gastrula stages and random integration mainly occurred at later stages of embryogenesis. This eventually led to the transgenic mosaicism. The MThGH-transferred common carp enhanced growth rate by 2-4 times in the founder juveniles and doubled the body weight in the adults. The transgenic common carp were more efficient in utilizing dietary protein than the controls. An "all-fish" gene construct CAgcGH has been made by splicing the common carp beta-actin gene (CA) promoter onto the grass carp growth hormone gene (gcGH) coding sequence. The CAgcGH-transferred Yellow River Carp have also shown significantly fast-growth trait. Combination of techniques of fish cell culture, gene transformation with cultured cells and nuclear transplantation should be able to generate homogeneous strain of valuable transgenic fish to fulfil human requirement in 21st century.

Animals↗

PubMed2000

Wave-intensity analysis: a new approach to coronary hemodynamics.

In 10 anesthetized dogs, we measured high-fidelity left circumflex coronary (P(LCx)), aortic (P(Ao)), and left ventricular (P(LV)) pressures and left circumflex velocity (U(LCx); Doppler) and used wave-intensity analysis (WIA) to identify the determinants of P(LCx) and U(LCx). Dogs were paced from the right atrium (control 1) or right ventricle by use of single (control 2) and then paired pacing to evaluate the effects of left ventricular contraction on P(LCx) and U(LCx). During left ventricular isovolumic contraction, P(LCx) exceeded P(Ao), paired pacing increasing the difference. Paired pacing increased DeltaP(X) (the P(LCx)-P(Ao) difference at the P(Ao)-P(LV) crossover) and average dP(LCx)/dt (P < 0.0001 for both). During this time, WIA identified a backward-going compression wave (BCW) that increased P(LCx) and decreased U(LCx); the BCW increased during paired pacing (P < 0.0001). After the aortic valve opened, the increase in P(Ao) caused a forward-going compression wave that, when it exceeded the BCW, caused U(LCx) to increase, despite P(LV) and (presumably) elastance continuing to increase. Thus WIA identifies the contributions of upstream (aortic) and downstream (microcirculatory) effects on P(LCx) and U(LCx).

Animals↗

PubMed2000

[Analysis of heavy oil fractions in high-temperature coal tar by capillary gas chromatography/fourier transform infrared spectrometry].

Capillary gas chromatography-Fourier transform infrared spectrometry-gas chromatography retention indices (GC/FTIR-RI), combined with the linear relationship between retention value and boiling points for polycyclic aromatic hydrocarbons, performed the determination of the composition of heavy oil fractions in high-temperature coal tar. More than 70 and 61 compounds were separated and identified in heavy oil fractions F7(300-330 degrees C) and F8(330-360 degrees C) respectively. The results are useful in coal tar distillation processing and pollution monitoring when such compounds are present.

Anthracenes↗

PubMed2000

[Studies on shape selective isopropylation products of coal tar naphthalene by gas chromatography/mass spectrometry].

Shape selective isopropylation products of coal tar naphthalene over different zeolite catalysts have been studied by capillary gas chromatography/mass spectrometry (CGC/MS) combined with computerized library search and manual interpretations of mass spectra. The analytical results have shown that products mainly consisted of some monosubstituted, disubstituted and a few trisubstituted naphthalenes. Except the low activity of HZSM-5 catalyst, all other zeolite catalysts have higher activity. HY and H beta catalytic activities were the highest, and their naphthalene conversions attained to 79.12 and 55.79 percent respectively, but their selectivities for 2-isopropylnaphthalene (beta-IPN), 2, 6-diisopropylnaphthalene (2, 6-DIPN) and 2, 7-diisopropylnaphthalene (2, 7-DIPN) were too low. ZM catalysts had good activity and much better selectivity, especially for ZM4-3, of which its 2,6-DIPN/2,7-DIPN ratio was 2.97. Therefore, some zeolite catalysts are recommended for shape selective isopropylation of coal tar naphthalene.

English Abstract↗

PubMed1999

A conserved motif N-terminal to the DNA-binding domains of myogenic bHLH transcription factors mediates cooperative DNA binding with pbx-Meis1/Prep1.

The t(1;19) chromosomal translocation of pediatric pre-B cell leukemia produces chimeric oncoprotein E2a-Pbx1, which contains the N-terminal transactivation domain of the basic helix-loop-helix (bHLH) transcription factor, E2a, joined to the majority of the homeodomain protein, Pbx1. There are three Pbx family members, which bind DNA as heterodimers with both broadly expressed Meis/Prep1 homeo-domain proteins and specifically expressed Hox homeodomain proteins. These Pbx heterodimers can augment the function of transcriptional activators bound to adjacent elements. In heterodimers, a conserved tryptophan motif in Hox proteins binds a pocket on the surface of the Pbx homeodomain, while Meis/Prep1 proteins bind an N-terminal Pbx domain, raising the possibility that the tryptophan-interaction pocket of the Pbx component of a Pbx-Meis/Prep1 complex is still available to bind trypto-phan motifs of other transcription factors bound to flanking elements. Here, we report that Pbx-Meis1/Prep1 binds DNA cooperatively with heterodimers of E2a and MyoD, myogenin, Mrf-4 or Myf-5. As with Hox proteins, a highly conserved tryptophan motif N-terminal to the DNA-binding domains of each myogenic bHLH family protein is required for cooperative DNA binding with Pbx-Meis1/Prep1. In vivo, MyoD requires this tryptophan motif to evoke chromatin remodeling in the Myogenin promoter and to activate Myogenin transcription. Pbx-Meis/Prep1 complexes, therefore, have the potential to cooperate with the myogenic bHLH proteins in regulating gene transcription.

3T3 Cells↗

PubMed1999

A common mechanism for antenna-to-Leg transformation in Drosophila: suppression of homothorax transcription by four HOM-C genes.

The Drosophila HOM-C genes encode transcription factors containing the DNA-binding homeodomain. Mutations in the HOM-C genes can cause specific homeotic transformation, suggesting that the HOM-C genes determine segmental identities by acting on different target genes. However, misexpression of several HOM-C genes in the antenna disc causes similar antenna-to-leg transformations. Here we show that the Scr, Antp, Ubx, and abd-A HOM-C genes all exert their effects through a common mechanism: suppressing the transcription of the homothorax (hth) homeobox gene and thereby preventing the nuclear localization of the Extradenticle homeodomain protein. We also show that ectopic hth expression can cause duplication of the proximodistal axis of the antenna, suggesting that it is involved in proximodistal development of the antenna.

Animals↗