Biomedical subjects

Jian Yang

Publications and source records attributed to Jian Yang.

At least 163 records · Page 9Linked to original sources

PubMed2002

Genome sequence of Shigella flexneri 2a: insights into pathogenicity through comparison with genomes of Escherichia coli K12 and O157.

We have sequenced the genome of Shigella flexneri serotype 2a, the most prevalent species and serotype that causes bacillary dysentery or shigellosis in man. The whole genome is composed of a 4 607 203 bp chromosome and a 221 618 bp virulence plasmid, designated pCP301. While the plasmid shows minor divergence from that sequenced in serotype 5a, striking characteristics of the chromosome have been revealed. The S.flexneri chromosome has, astonishingly, 314 IS elements, more than 7-fold over those possessed by its close relatives, the non-pathogenic K12 strain and enterohemorrhagic O157:H7 strain of Escherichia coli. There are 13 translocations and inversions compared with the E.coli sequences, all involve a segment larger than 5 kb, and most are associated with deletions or acquired DNA sequences, of which several are likely to be bacteriophage-transmitted pathogenicity islands. Furthermore, S.flexneri, resembling another human-restricted enteric pathogen, Salmonella typhi, also has hundreds of pseudogenes compared with the E.coli strains. All of these could be subjected to investigations towards novel preventative and treatment strategies against shigellosis.

Amino Acid Sequence↗

PubMed2002

Hydrophobic probe binding of beta-lactoglobulin in the native and molten globule state induced by high pressure as affected by pH, KIO(3) and N-ethylmaleimide.

High hydrostatic pressure (HHP) at 500 MPa and 50 degrees C induces beta-LG into the molten globule state. Retinol, cis-parinaric acid (CPA), and 1-anilino-naphthalene-8-sulfonate (ANS) fluorescence from pH 2.5 to 10.5 in the presence of the native and molten globule states of beta-LG indicate that retinol binds to beta-LG in the calyx, CPA at the surface hydrophobic site, and ANS in multiple hydrophobic sites. HHP treatment results in a decrease of beta-LG affinity for retinol and CPA, suggesting conformational changes in the calyx and surface hydrophobic site of beta-LG during HHP treatment. beta-LG treated by HHP in the presence of N-ethylmaleimide (NEM) retains retinol affinity, suggesting that NEM protects the calyx conformation of beta-LG during HHP treatment. HHP treatment of beta-LG in the presence of KIO(3) exhibits a great decrease of CPA affinity compared to HHP-treated beta-LG in the absence of KIO(3), suggesting the formation of non-native disulfide bonding at the CPA binding site.

Anilino Naphthalenesulfonates↗

PubMed2002

Allele sharing for schizophrenia and schizo-affective disorder within a region of Homo sapiens specific XY homology.

A case (based upon an association with cerebral asymmetry) has been presented for a gene for psychosis within the Xq21.3/Yp region of homology that is specific to Homo sapiens. We tested this hypothesis using the pentanucleotide marker DXYS 156 that is located within this region. In 84 families affected by schizophrenia or schizo-affective disorder no tendency toward increased allele sharing amongst siblings was observed (chi(2) = 0.002). We conclude either that this region does not include a gene predisposing to psychosis or that if it does, the relevant variation is epigenetic rather than sequence-based. With respect to the latter possibility we draw attention to the recent evolutionary history of the Xq21.3/Yp region. Genes within the region are in transition to protection from X inactivation and therefore may be epigenetically labile.

Alleles↗

PubMed2002

Alterations in conserved Kir channel-PIP2 interactions underlie channelopathies.

Inwardly rectifying K(+) (Kir) channels are important regulators of resting membrane potential and cell excitability. The activity of Kir channels is critically dependent on the integrity of channel interactions with phosphatidylinositol 4,5-bisphosphate (PIP(2)). Here we identify and characterize channel-PIP(2) interactions that are conserved among Kir family members. We find basic residues that interact with PIP(2), two of which have been associated with Andersen's and Bartter's syndromes. We show that several naturally occurring mutants decrease channel-PIP(2) interactions, leading to disease.

Amino Acid Sequence↗

PubMed2002

A draft sequence of the rice genome (Oryza sativa L. ssp. indica).

We have produced a draft sequence of the rice genome for the most widely cultivated subspecies in China, Oryza sativa L. ssp. indica, by whole-genome shotgun sequencing. The genome was 466 megabases in size, with an estimated 46,022 to 55,615 genes. Functional coverage in the assembled sequences was 92.0%. About 42.2% of the genome was in exact 20-nucleotide oligomer repeats, and most of the transposons were in the intergenic regions between genes. Although 80.6% of predicted Arabidopsis thaliana genes had a homolog in rice, only 49.4% of predicted rice genes had a homolog in A. thaliana. The large proportion of rice genes with no recognizable homologs is due to a gradient in the GC content of rice coding sequences.

Arabidopsis↗

PubMed2002

Diminished hepatic response to fasting/refeeding and liver X receptor agonists in mice with selective deficiency of sterol regulatory element-binding protein-1c.

Two treatments, fasting/refeeding and administration of liver X receptor (LXR) agonists, elevate the mRNA for sterol regulatory element-binding protein-1c (SREBP-1c) and enhance lipid synthesis in liver. These treatments do not affect the mRNA for SREBP-1a, an alternative transcript from the same gene. Through homologous recombination, we eliminated the exon encoding SREBP-1c from the mouse genome, leaving the SREBP-1a transcript intact. On a normal diet, livers of SREBP-1c(-/-) mice manifested reductions in multiple mRNAs encoding enzymes of fatty acid and triglyceride synthesis, including acetyl-CoA carboxylase (ACC) and fatty acid synthase (FAS). In contrast, SREBP-1c(-/-) livers showed a compensatory increase in hepatic SREBP-2 mRNA, accompanied by increased mRNA levels for cholesterol biosynthetic enzymes. In fasted/refed animals, ACC and FAS mRNAs rose, but not to the same extent as in wild-type livers. The refeeding-induced increase in SREBP-1c(-/-) mice was greater than in mice lacking SREBP cleavage-activating protein (SCAP), in which all nuclear SREBPs are absent. Thus, SREBP-2 and/or SREBP-1a can substitute partially for SREBP-1c in permitting an insulin-mediated increase in ACC and FAS mRNAs. In contrast, mRNAs for several other lipogenic enzymes (glucose-6-phosphate dehydrogenase, malic enzyme, glycerol-3-phosphate acyltransferase, and stearoyl-CoA desaturase-1) showed a complete failure of the normal inductive response to refeeding, indicating specific reliance on SREBP-1c. Moreover, these mRNAs, as well as multiple other lipogenic mRNAs, showed a markedly blunted response to the LXR agonist T090137, indicating an essential role of SREBP-1c in the LXR response.

Acetyl-CoA Carboxylase↗

PubMed2002

Substrate specificity of protein tyrosine phosphatase: differential behavior of SHP-1 and SHP-2 towards signal regulation protein SIRPalpha1.

The substrate specificity of catalytic domains and the activation of full length protein tyrosine phosphatases, SHP-1 and SHP-2 have been investigated using synthetic phosphotyrosyl peptides derived from SIPRalpha1. We found that the catalytic domains of SHP-1 and SHP-2 exhibit different substrate specificity towards a longer trideca-peptide pY(469+3) ((-7)RPEDTLTpYADLDM(+5)) and not to the shorter decapeptide pY(469) ((-5)EDTLTpYADLD(+4)), the former being the substrate of SHP-2 only. Furthermore, the activation of full-length SHP-1 and not the SHP-2 by the deca/trideca-peptides suggested SIRPalpha 1 to be possibly acting as both an upstream activator and a substrate for SHP-1, and merely as the downstream substrate for SHP-2 in signaling events.

Antigens, Differentiation↗

PubMed2002

Enhanced cell affinity of poly (D,L-lactide) by combining plasma treatment with collagen anchorage.

Surface properties of poly (D,L-lactide) (PDLLA) were modified by combining plasma treatment and collagen modification. The changes of surface properties were characterized by contact angles, surface energy, X-ray photoelectron spectra and scanning electron microscopy. The mouse 3T3 fibroblasts were used as model cells to evaluate the cell affinity of PDLLA before and after modification. Effects of different modification methods including plasma treatment, collagen coating and combining plasma treatment with collagen anchorage were investigated and compared. The results showed that the hydrophilicity and surface-free energy were improved and reduced, respectively, after each modification. Plasma pre-treatment could improve the roughness as it incorporated the polar groups and positively charged groups onto the sample surface; so the plasma pre-treated surface would benefit in anchoring more collagen tightly. As a result, cell affinity of PDLLA modified by combining plasma treatment with collagen anchorage was greatly improved. The modified materials could endure rinsing by PBS, which would facilitate further application when the modified materials were used as cells scaffold in tissue engineering.

3T3 Cells↗

PubMed2002

A novel porous cells scaffold made of polylactide-dextran blend by combining phase-separation and particle-leaching techniques.

In this study, a kind of biodegradable material was developed by blending polylactide (PLA) with natural biodegradable dextran, and a novel sponge-like scaffold made of it was fabricated thereof using solvent-casting and particle-leaching technique. To obtain a uniform blend of PLA and dextran by simple solvent-casting method, hydroxyls of dextran should be protected via trimethylsilyl (TMS) groups to make dextran soluble in organic solvents. Benzene was found among the few solvents that could dissolve this TMS-protected dextran (TMSD) well, however, it was not a good solvent for PLA. Therefore, a homogeneous mixed solution of PLA and TMSD could be obtained when a mixture of dichloroform (DCM) and benzene (v/v = 6/4) was used. By this technique, PLA-dextran blend films and even PLA films were observed a microporous structure (pore size around 5-10 microm) formation throughout the films under scanning electron microscope (SEM). Scaffolds that were prepared by dissolving PLA and TMSD in mixed solvent of DCM and benzene and using salt as porogen, were observed the formation of micropores (pore size around 5-10 microm) in the cellular walls of macropores (pore size around 100-200 microm). This microporous structure was closely related to the phase separation occurring during films or foams formation, which was mainly due to the different solubility of PLA and TMSD in benzene, as well as the different evaporation rates of DCM and benzene. In comparison with PLA, the surface and bulk hydrophilicity of PLA-dextran blend films or foams were significantly improved after the TMS groups were removed in methanol, and the results of cell culture on these polymeric substrates exhibited an enhancement on cell attachment and proliferation.

3T3 Cells↗

PubMed2002

The uptake of manganese in brain endothelial cultures.

The present study focused on central nervous system (CNS) transport kinetics of manganese phosphate and manganese sulfate; these findings were correlated with the transport kinetics of manganese chloride (MnCl2), a model Mn compound that has been previously studied. A series of studies was performed to address the transport of Mn salts in confluent cultured endothelial cells. The initial rate of uptake (5 min) of Mn salts (chloride, sulfate, and phosphate) in rat brain endothelial (RBE4) cell cultures is salt-dependent, with the highest rates of uptake for Mn chloride and Mn sulfate (as reflected by the greatest displacement of 54Mn compared with control). Mn phosphate had a lower rate of uptake than the other two Mn salts. These data show that brain endothelial cells efficiently transport Mn sulfate.

Animals↗

PubMed2002

Effects of removal of the N-terminal amino acid residues on the activity and conformation of firefly luciferase.

A series of deletion mutants were constructed using polymerase chain reaction (PCR) to investigate the roles of luciferase N-terminal residues. The coding sequences of the first 0 (Luc0), 6 (Luc6), 7 (Luc7), 8 (Luc8), 9 (Luc9), 10 (Luc10) and 20 (Luc20) amino acids of the N-terminus were deleted and inserted into the prokaryotic expression vector pBV220. The results showed that the enzymes were completely inactivated when the first eight or more N-terminal amino acids were removed. The recombinant Luc0 and mutants Luc6 and Luc7 were purified to homogeneity by ammonium sulfate precipitation and liquid chromatography for determination of their activity and conformational changes. The activity assay showed that removal of the first six amino acids resulted in 29% loss of enzymatic activity while removal of the first seven amino acids resulted in nearly complete inactivation (with remaining activity <0.5% of the original activity). Circular dichroism spectra showed no significant secondary structure changes. But the fluorescence emission maximum red-shift indicated some conformational changes. Luc6 and Luc7 were more sensitive to guanidine unfolding than Luc0. The present result indicated the significant role of Ile7 to the luciferase stability.

Animals↗

PubMed2002

Short-term administration of basic fibroblast growth factor enhances coronary collateral development without exacerbating atherosclerosis and balloon injury-induced vasoproliferation in atherosclerotic rabbits with acute myocardial infarction.

We evaluated the effect of basic fibroblast growth factor (bFGF) on the extent of atherosclerosis and balloon injury-induced vasoproliferation in atherosclerotic animals with acute myocardial infarction (AMI). Fifty-six rabbits were fed a 1% cholesterol diet. Balloon injury of iliac arteries and experimental acute myocardial infarction were induced in the same animals. Rabbits were then randomized to a bFGF group (20 pg/day, intravenously) or a control group (intravenous saline solution). The beneficial effects of bFGF on cardiac function, infarct size, and collateral vessel development, and the possible effect on vasoproliferation of balloon-injured vessels, were measured after 1 and 2 weeks. The extent of atherosclerosis was measured after 1, 2, and 4 weeks. Our results showed that bFGF significantly reduced infarct size and increased collateral-vessel density (P <.01) in infarct areas. Cardiac function was better in the bFGF group than in corresponding controls (P <.05). Similar beneficial effects of bFGF were noted in animals after 1- and 2-week treatments. However, the extent of atherosclerosis and the vasoproliferation in chronic atherosclerotic vessels induced by balloon injury and cholesterol diet were not significantly different between the two groups. Our results suggest that short-term treatment with bFGF enhances collateral development and produces maximum therapeutic benefits without exacerbating atherosclerosis and cell proliferation in stenotic vessels after AMI in atherosclerotic rabbits.

Angioplasty, Balloon, Coronary↗

PubMed2002

Silicone implant in augmentation rhinoplasty.

During the past 6 years the authors have treated 406 patients with classic silicone augmentation rhinoplasty. The types and incidence of complications after subcutaneous or subfascial implantation are examined and discussed. They propose that most complications are related to the depth of the implant and the character of the tissues. To improve their operation and to prove their hypothesis, they performed subperiosteal augmentation rhinoplasty in 22 patients with satisfactory results. At the same time, they investigated the biomechanical properties of human nasal periosteum and fascia, including tensile strength, the stress-strain relationship, and stress relaxation characteristics under uniaxial tension. Although it has less failure strain, the periosteum has more tensile strength than fascia. So, in the view of biomechanics, the periosteum is thicker, tougher, and stiffer than fascia, and thus more suitable for covering silicone implants.

Adolescent↗

PubMed2002

A complete sequence of the T. tengcongensis genome.

Thermoanaerobacter tengcongensis is a rod-shaped, gram-negative, anaerobic eubacterium that was isolated from a freshwater hot spring in Tengchong, China. Using a whole-genome-shotgun method, we sequenced its 2,689,445-bp genome from an isolate, MB4(T) (Genbank accession no. AE008691). The genome encodes 2588 predicted coding sequences (CDS). Among them, 1764 (68.2%) are classified according to homology to other documented proteins, and the rest, 824 CDS (31.8%), are functionally unknown. One of the interesting features of the T. tengcongensis genome is that 86.7% of its genes are encoded on the leading strand of DNA replication. Based on protein sequence similarity, the T. tengcongensis genome is most similar to that of Bacillus halodurans, a mesophilic eubacterium, among all fully sequenced prokaryotic genomes up to date. Computational analysis on genes involved in basic metabolic pathways supports the experimental discovery that T. tengcongensis metabolizes sugars as principal energy and carbon source and utilizes thiosulfate and element sulfur, but not sulfate, as electron acceptors. T. tengcongensis, as a gram-negative rod by empirical definitions (such as staining), shares many genes that are characteristics of gram-positive bacteria whereas it is missing molecular components unique to gram-negative bacteria. A strong correlation between the G + C content of tDNA and rDNA genes and the optimal growth temperature is found among the sequenced thermophiles. It is concluded that thermophiles are a biologically and phylogenetically divergent group of prokaryotes that have converged to sustain extreme environmental conditions over evolutionary timescale.

Bacillaceae↗

PubMed2002

Assessing the DSM-IV structure of personality disorder with a sample of Chinese psychiatric patients.

The validity of the three-cluster system of personality disorders (PDs) in the latest version of the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV; APA, 1994) was examined in a sample of Chinese psychiatric patients (n = 227), who completed the self-report Personality Disorders Questionnaire for DSM-IV (PDQ-4; Hyler, 1994) and who were also administered the clinician-rated Personality Disorders Interview-IV (PDI-IV; Widiger, Mangine, Corbit, Ellis, & Thomas,). Using confirmatory factor analysis, a three-factor model corresponding to the DSM-IV clusters was tested and compared statistically to a one-factor model and a set of random, three-factor models. Only the clinician-rated instrument supported the DSM-IV three-cluster model, and then only when the factors were allowed to correlate. Results from the theoretically more rigorous uncorrelated model testing did not support the DSM-IV model for either assessment modality.

Adult↗

PubMed2002

[A clinicopathologic study of CD30-positive sinusoidal large B-cell lymphoma].

OBJECTIVE: To explore the clinicopathologic features of CD30-positive sinusoidal large B-cell lymphoma (CD30 + SLBCL) and its relative correlation with Epstein-Barr virus (EBV). METHODS: Two cases of CD30 + SLBCL, a 65-year-old men and a 85-year-old women were morphologically and immunophenotypically analyzed. EBV status was also evaluated through not only the polymerase chain reaction (PCR) amplification to the EBV Bam HIW DNA sequence, but also an immunohistochemical detection of the latent membrane protein 1 (LMP1). RESULTS: The patients presented with similarly superficial lymphadenopathy. One of them died of the tumor within 10 months. Microscopically, both of the neoplasms were characterized by a cohesive sinus growth pattern and the monomorphic cytology of the tumor cells. Immunohistochemically, They were both positive for CD45, CD30, and CD20 or CD79alpha, whereas neither expressed EMA, ALK1, nor any histiocytic/T-lineage markers. No evidence of EBV-infection could be found either. CONCLUSIONS: CD30 + SLBCL is a morphologically and immunophenotypically distinctive variant of diffuse large B-cell lymphoma, which should be distinguished from T/null cell type anaplastic large cell lymphoma and some other nodal lesions with a predominantly sinusoidal infiltrative pattern. CD30 + SLBCL may not be correlation with EBV.

Aged↗

PubMed2002

The morphometry and biomechanical properties of the rat small intestine after systemic treatment with epidermal growth factor.

Morphometric and passive biomechanical properties were studied in isolated segments of the duodenum, jejunum and ileum in 22 EGF-treated rats and 12 control rats. The rats were allocated to groups with EGF treatment for 2, 4, 7, and 14 days (n = 6 for each EGF treatment group except n = 4 for the 14 days group) or saline treatment (n = 3 for each group). The intestinal segments were pressurized with Krebs solution from 0 to 8 cmH2O for duodenum and 0 to 6 cmH2O for jejunum and ileum using a ramp distension protocol. The diameter and length were recorded at different pressure levels. Circumferential and longitudinal stresses (force per area) and strains (deformation) were computed from the length, diameter, pressure and the zero-stress state data. EGF treatment was associated with pronounced morphometric changes, e.g., the wall thickness, wall area, and the circumferential lengths significantly increased during EGF treatment in all intestinal segments (P < 0.05). Histological analysis showed that the thickness and area of the layers increased after EGF treatment. With respect to the biomechanical data, the opening angle increased in all segments during EGF treatment with the highest value in the 14 days EGF treatment group (P < 0.05). The same result was found for residual strain and the residual strain gradient through the intestinal wall. Linear regression analysis demonstrated that the opening angle mainly depended on the mucosa thickness and area. Furthermore, the circumferential stiffness increased in the duodenum and decreased in the jejunum and ileum during EGF treatment. A plateau was reached after 7 days where after it started to normalize (P < 0.01). In the longitudinal direction, all intestinal segments became stiffer after EGF treatment for 7 days. After 14 days the curve started to normalize in duodenum and jejunum but not in the ileum.

Animals↗

PubMed2002

[Comparison of biomechanical properties between human nasal periosteum and fascia].

There has been a lot of controversies on which layer the silastic implants should be inserted in the augmentation rhinoplasty, i.e. subperiosteal or deep subfascial. This study is to investigate the biomechanical properties of human nasal periosteum and deep fascia, including tensile strength, stress-strain and stress relaxation characters under uniaxial tension system. The periosteum is stronger in tensile strength than that of the fascia, but it is less elastic. Under a sudden increase of load, the periosteum relaxes far less than the fasia. Therefore, in view of biomechanics, the periosteum is thicker, tougher, stiffer and less relaxation than facia, thus has a better fixation effect.

Biomechanical Phenomena↗