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Biomedical subjects

W Xu

Publications and source records attributed to W Xu.

At least 145 records · Page 8Linked to original sources
PubMed2001

[Detection of Immunoglobulin light chain restriction of mucosa-associated lymphoid tissue type gastric lymphoma using mRNA in situ hybridization].

OBJECTIVE: To evaluate the usefulness of in situ hybridization for Immunoglobulin kappa and lambda light chain mRNA to detect light chain restriction in the diagnosis of primary gastric lymphoma (PGL) of mucosa-associated lymphoid tissue (MALT) type. METHODS: Twenty-seven cases of PGL of MALT type and 5 cases of gastritis were analyzed using in situ hybridization with fluorescent isothiocyanate (FITC)-labeled oligonucleotide probes for kappa and lambda light chain mRNA. The kappa:lambda ratios of tumor cells, lymphocytes and plasma cells were analyzed to detect light chain restriction and clonal plasma cells. RESULTS: Light chain restriction was found in 10 of 27 (37%) cases of PGL cases (in 5/9 low grade and 5/18 in high grade). Clonal plasma cells were detected in low grade but not in high-grade cases. No light chain restriction was found in gastritis specimens, the adjacent tissue of tumors or the distant stomach mucosa in lymphoma cases. CONCLUSIONS: The detection of clonality using mRNA in situ hybridization could be a helpful diagnostic tool for gastric lymphoma. The presence of clonal plasma cells can be a marker of the early lesion of low-grade PGL.

Diagnosis, Differential↗
PubMed2001

[The Influence of stress inhibition on the plasma levels of LPS, pro-inflammatory and Th1/Th2 cytokines in severely scalded rats].

OBJECTIVE: To explore the influence of stress inhibition on the plasma levels of LPS pro-inflammatory and Th1/Th2 cytokines in severely scalded rats. METHODS: Sprague-Dawley (SD) rats inflicted by 30% TBSA of deep partial thickness burn were employed as the model and randomly divided into burn with immediate resuscitation (A) and burn with immediate resuscitation and soluble cocktail (B) groups. Plasma was harvested from peripheral blood at different postburn time points for the determination of the levels of LPS, IL-1alpha, IL-6, TNFalpha, IL-8, IL-2, IFN-gamma, IL-4 and IL-10 in the rats of the two groups. And the rats inflicted by sham scalding were taken as control group (C). RESULTS: The postburn plasma levels of LPS, IL-1alpha, IL-4 and IL-10 increased gradually, while the plasma levels of IL-6, TNF, IL-8, IL-2 and IFN increased initially and decreased thereafter. The increasing ranges of LPS and these inflammatory cytokines were higher in A group, in which the increases of IL-1alpha, IL-6 and IL-4 appeared earlier in A (6 PBH) than those in B (12 PBH) groups. CONCLUSION: Prompt fluid resuscitation and stress inhibition could delay and ameliorate the postburn inflammatory reaction, decrease the production of Th2 cytokine and partially restore the production of Th1 cytokine after 48 PBH.

Animals↗
PubMed2001

[The adhesive and migrating function of human epithelial cells opsonized by fibronectin].

OBJECTIVE: To investigate the adhesive and migrating function of human epithelial keratiocytes during in vitro culture. METHODS: The adhesive and migrating function was determined in freshly isolated EKCs and those cultured for 7 similar 10 days after being opsonized by fibronectin (FN). The expressions of alpha(5)beta(1) receptors in EKC were examined with indirect immunofluorescence staining methods before and after culture. RESULTS: (1) The adhesive and migrating indices after FN opsonization of EKCs freshly isolated EKCs were obviously lower than those cultured for 7 similar 10 days (P < 0.01). (2) There exhibited positive staining of the expression of alpha(5)beta(1) receptors in the EKC after 1 day culture and in the proliferative epithelia after in vitro culturing of a tissue mass. While there exhibited strongly positive staining of the peripheral proliferative epithelia of the EKCs and tissue mass after 7 days of culture, negative or weakly positive stainings were found in freshly isolated EKCs. CONCLUSION: (1) There existed significant difference of biological function between the freshly isolated EKCs and those cultured for 7 similar 10 days. (2) The strongest expression of alpha(5)beta(1) receptors was observed at the active proliferative site (peripheral proliferative epithelia of a tissue mass) and in the biological active period (cultured for 7 days) of EKCs. (3) The adhesive and migrating function of EKCs could be effectively induced and activated by in vitro culture, which enabled the EKC to alter from a relatively biologically functional static state to an actively functional state.

Cell Adhesion↗
PubMed2001

A random-effects mixture model for classifying treatment response in longitudinal clinical trials.

A random-effects regression model that allows the random coefficients to have a multivariate normal mixture distribution is described for classifying treatment response in longitudinal clinical trials. The proposed model is capable of dealing with longitudinal data from unknown heterogeneous populations. As applied to longitudinal clinical trials, for example, the model can distinguish subgroups of treatment response. Use of the proposed model is illustrated by analyzing data from two psychiatric clinical trials. The first includes depressed patients assigned to drug treatment who are repeatedly measured in terms of their level of depression. The second trial examined schizophrenic patients longitudinally who were assigned to either a drug or placebo condition. For both, the random-effects mixture model allows an assessment of whether patients comprise distinct populations in terms of their treatment response. Based on parameter estimates of the mixture model, ample evidence for a mixture of response to treatment is observed for both datasets.

Algorithms↗
PubMed2001

[Study on vibration mode of different phonatory source and compensation after partial laryngectomy].

OBJECTIVE: To investigate the nature of pathological voice production and compensatory mechanism after partial laryngectomy. METHODS: Vocal function of 93 cases following partial laryngectomy (28 cases of horizontal partial laryngectomy, 35 vertical partial laryngectomy, 30 horizontal-vertical partial laryngectomy) were examined by acoustic analysis, aerodynamic analysis and videostroboscopic examination. RESULTS: Horizontal supraglottic laryngectomy(HL) resulted in slight dysphonia after operation. The cover of vocal fold was hypertrophic and edematous. Mucosa wave was increased. Acoustic analysis showed significant difference between normal and horizontal laryngectomy groups(P < 0.05). Vertical laryngectomy(VL) resulted in moderate-severe dysphonia. Acoustic analysis was significantly worse in VL than in normal group(P < 0.01). The nonglottic phonatory source was the contralateral ventricular fold or contralateral vestibular mucosa (arytenoid mucosa, root mucosa of glottis) to approximate the reconstructed flap. It was noted that contralateral vocal fold did not participate in vibration. Horizontal-vertical partial laryngectomy (HVL) resulted in moderate-severe dysphonia. Acoustic analysis of HVL was significantly worse than that of normal phonation(P < 0.01). The site of compensatory mucosa vibration upon phonation was the contralateral vocal fold or contralateral hypertrophic arytenoid mucosa. The thinner the flap, the better the vocal quality was. Vocal quality of VL was worse than that of HVL in regard to shimmer, jitter, normalized noise energy, maximal phonation time and harmonic-noise ratio, but there was no significant difference between them. CONCLUSIONS: Partial laryngectomy has different vibrating compensatory modes: Voice function of horizontal partial laryngectomy was the best as it preserved the normal vibration mode; vertical partial laryngectomy was the worst with the nonglottic vibrating source of reconstructed flap-ventricular fold. The reconstructed flap, ventricular fold, mucosa of epiglottis and arytenoid take predominantly part in neoglottal vibration. The situation, volume and pliability characteristic of reconstructed flap was also important to vocal quality.

Aged↗
PubMed2001

[Study on the inclusion interaction of beta-cyclodextrin with phosphatidylcholine by UV spectra].

A kind of cyclic oligosaccharides, beta-cyclodextrin (beta-CD) was found to possess inclusion ability with phosphatidylcholine (PC). The inclusion compound of beta-CD with PC was studied by elemental analysis of solid inclusion compound and UV spectra of different mole ratios beta-CD/PC in H2O-MeOH solution. The results indicate that two moles of beta-CD include one mole PC to form inclusion compound by Van Der Waals force, hydrophobic interaction and hydrogen bounds, etc. The selective binding ability of beta-CD with PC has been discussed from the viewpoint of size/shape-fitting and geometry fitting between the host cavity and the gust molecular. The solubility in aqueous solution, the oxidation stability of PC was increased by inclusion with beta-CD.

Chemical Phenomena↗
PubMed2001

[How to manage your dental clinic successfully].

For adapting the continuing reform of our medical care structure, further developing the standardize of the private dental clinics in China, in this article the key elements of the dental clinic management were presented, to emphasize the importance of medical service concept re new and team work build-up, also the clinic model of the modern dentistry was discussed.

English Abstract↗
PubMed2000

Cloning of the mouse Pax4 gene promoter and identification of a pancreatic beta cell specific enhancer.

Pax4 encodes a paired-box transcription factor and is essential for the differentiation of islet cells since the Pax4 homozygous mutant mice lack mature beta and delta cells. However, little is known about the transcriptional regulation of the Pax4 gene. We isolated and sequenced a 2.4-kb mouse genomic DNA fragment containing the 5' flanking sequence of Pax4 and identified a previously unrecognized intron. Primer extension revealed that this TATA-less promoter had only one transcription start site. The promoter activity of this fragment with various deletion mutants when tested in beta and non-beta cell lines indicated the presence of a beta-cell specific enhancer in the region, -1858 to -1954 bp. DNase 1 footprinting and gel retardation assays indicated that nuclear proteins from betaHC3 cells interacted with two sequences which contained putative CdxA/Nkx.2 and GATA-1,-2 binding sites. Site-directed mutagenesis indicated that both of these regions were necessary for beta-cell specific enhancer activity.

5' Untranslated Regions↗
PubMed2000

Crystal structure of a beta-catenin/Tcf complex.

The Wnt signaling pathway plays critical roles in embryonic development and tumorigenesis. Stimulation of the Wnt pathway results in the accumulation of a nuclear beta-catenin/Tcf complex, activating Wnt target genes. A crystal structure of beta-catenin bound to the beta-catenin binding domain of Tcf3 (Tcf3-CBD) has been determined. The Tcf3-CBD forms an elongated structure with three binding modules that runs antiparallel to beta-catenin along the positively charged groove formed by the armadillo repeats. Structure-based mutagenesis defines three sites in beta-catenin that are critical for binding the Tcf3-CBD and are differentially involved in binding APC, cadherin, and Axin. The structural and mutagenesis data reveal a potential target for molecular drug design studies.

Amino Acid Motifs↗
PubMed2000

Detection and characterization of a 36-kDa peptide in C-terminal region of a 24-kDa vacuolar protein (VP24) precursor in anthocyanin-producing sweet potato cells in suspension culture.

A 24-kDa vacuolar protein (VP24) was found to accumulate in anthocyanin-producing sweet potato cells (Ipomoea batatas Lam.) in suspension culture [Nozue et al., Plant Physiol. 115 (1997) 1065]. VP24 cDNA (accession No. AB025531) encodes a 96.3-kDa large precursor protein with a C-terminal propeptide which contains the eight putative transmembrane domains. The mature VP24 is probably involved in the formation of intravacuolar pigmented globules (cyanoplasts) in highly anthocyanin-containing vacuoles, but the biological function of the C-terminal region including the putative transmembrane domains is unknown. To confirm the expression and characterize the C-terminal region in the VP24 protein precursor in the anthocyanin-producing cells, polyclonal antibodies were developed against the fusion protein, including the C-terminal region, expressed in Escherichia coli. Western blot analysis showed that a 36-kDa peptide (VP36) localized in anthocyanin-containing vacuoles was expressed under continuous illumination, but not in darkness. The expression pattern of VP36 showed high similarity to VP24. These results suggested that VP36 may be derived from the large VP24 protein precursor; it includes several of the hydrophobic domains in the C-terminal region.

Journal Article↗
PubMed2000

Calreticulin modulates capacitative Ca2+ influx by controlling the extent of inositol 1,4,5-trisphosphate-induced Ca2+ store depletion.

Calreticulin (CRT) is a highly conserved Ca(2+)-binding protein that resides in the lumen of the endoplasmic reticulum (ER). We overexpressed CRT in Xenopus oocytes to determine how it could modulate inositol 1,4,5-trisphosphate (InsP(3))-induced Ca(2+) influx. Under conditions where it did not affect the spatially complex elevations in free cytosolic Ca(2+) concentration ([Ca(2+)](i)) due to InsP(3)-induced Ca(2+) release, overexpressed CRT decreased by 46% the Ca(2+)-gated Cl(-) current due to Ca(2+) influx. Deletion mutants revealed that CRT requires its high capacity Ca(2+)-binding domain to reduce the elevations of [Ca(2+)](i) due to Ca(2+) influx. This functional domain was also required for CRT to attenuate the InsP(3)-induced decline in the free Ca(2+) concentration within the ER lumen ([Ca(2+)](ER)), as monitored with a "chameleon" indicator. Our data suggest that by buffering [Ca(2+)](ER) near resting levels, CRT may prevent InsP(3) from depleting the intracellular stores sufficiently to activate Ca(2+) influx.

Animals↗
PubMed2000

Identification and characterization of differentially expressed genes in the early response phase during liver regeneration.

It has been suggested that the early response was a critical regulator of the remaining quiescent liver cells reentering the cell cycle after partial hepatectomy. The identification of genetic factors and function important in the early response phase during liver regeneration after partial hepatectomy will help in understanding the underlying molecular mechanisms of hepatic injuries. Through the application of complementary DNA representational difference analysis (RDA), we have identified genes that are up-regulated in early response phase during liver regeneration. Results from slot blot and Northern blot analysis confirmed that the RDA products were truly differentially expressed. In addition to well-characterized up-regulated genes during liver regeneration, including IGFBP-1, LRF-1, and metallothionein, we demonstrate the differential expression of at least 6 genes previously not known to be associated with liver regeneration. PC3 and TEC genes were identified as immediate-early response genes and were dramatically increased following partial hepatectomy. Ribosomal protein L6, ribosomal protein S7, chaperonin 10, and cytochrome oxidase I were identified to be up-regulated 4- to 5-fold after 70% partial hepatectomy. In addition to the known genes, 7 novel genes were isolated. Among them, two genes showed their up-regulation in liver regeneration by Northern blot analysis. One was exclusively expressed in liver, and no expression was observed in other tissues. Peak expression, 30-fold above baseline, occurred 60 min after 70% hepatectomy. Cycloheximide pretreatment could not suppress the induction of this gene, indicating that this gene as a novel immediate-early response gene following partial hepatectomy. The novel gene, which was represented three times in the differential clones, may be one of the highly up-expressed genes in regenerating liver. Its transcript is undetectable in normal liver; its level of mRNA increased by 0.5 h after 2/3 partial hepatectomy, reaching a maximum at 2 h. This gene is similar to human alpha-1-beta-glycoprotein (40%). These results suggest a role of these genes in the early response phase of liver regeneration.

Animals↗
PubMed2000

Induction of ref-1 ensures AP-1 activation in intracellular oxidative environment of IL-2-stimulated BA/F3beta cells.

Our previous study of interleukin-2 (IL-2) signaling found that redox factor-1 (Ref-1) mRNA was upregulated by IL-2. In this study, we further studied the function of Ref-1 in the potential redox regulation of IL-2 signaling in BA/F3beta cells. Western blot analysis confirmed that IL-2 stimulation increases Ref-1 protein. Flow cytometric assay by using 2',7'-dichlorofluorescin diacetate indicated that IL-2 stimulation results in an oxidative shift of intracellular environment. However, IL-2-induced activator protein-1 (AP-1) is oxidation-sensitive. Gel shift assays of nuclear extracts immunodepleted of Ref-1 protein demonstrated that IL-2-induced AP-1 DNA binding is dependent on the presence of Ref-1. This was further confirmed by the restoration of AP-1 DNA binding upon the re-addition of immunoprecipitated Ref-1. Additionally, reporter gene assays showed that AP-1 transcriptional activity was enhanced by the overexpression of Ref-1 and attenuated by the introduction of antisense Ref-1. These results suggest that the induction of Ref-1 ensures AP-1 activation in the intracellular oxidative environment of IL-2-stimulated BA/F3beta cells.

Base Sequence↗
PubMed2000

The conserved cysteine 7.38 residue is differentially accessible in the binding-site crevices of the mu, delta, and kappa opioid receptors.

Binding pockets of the opioid receptors are presumably formed among the transmembrane domains (TMDs) and are accessible from the extracellular medium. In this study, we determined the sensitivity of binding of [(3)H]diprenorphine, an antagonist, to mu, delta, and kappa opioid receptors to charged methanethiosulfonate (MTS) derivatives and identified the cysteine residues within the TMDs that conferred the sensitivity. Incubation of the mu opioid receptor expressed in HEK293 cells with MTS ethylammonium (MTSEA), MTS ethyltrimethylammonium (MTSET), or MTS ethylsulfonate (MTSES) inhibited [(3)H]diprenorphine binding with the potency order of MTSEA > MTSET > MTSES. Pretreatment of mu, delta, and kappa opioid receptors with MTSEA dose-dependently inhibited [(3)H]diprenorphine binding with MTSEA sensitivity in the order of kappa > mu >> delta. The effects of MTSEA occurred rapidly, reaching the maximal inhibition in 10 min. (-)-Naloxone, but not (+)-naloxone, prevented the MTSEA effect, demonstrating that the reaction occurs within or in the vicinity of the binding pockets. Each cysteine residue in the TMDs of the three receptors was mutated singly, and the effects of MTSEA treatment were examined. The mutants had similar affinities for [(3)H]diprenorphine, and C7. 38(321)S, C7.38(303)S, and C7.38(315)S mutations rendered mu, delta, and kappa opioid receptors less sensitive to the effect of MTSEA, respectively. These results indicate that the conserved Cys7.38 is differentially accessible in the binding-site crevice of these receptors. The second extracellular loop of the kappa receptor, which contains several acidic residues, appears to play a role, albeit small, in its higher sensitivity to MTSEA, whereas the negative charge of Glu6.58(297) did not. To the best of our knowledge, this is the first report to show that a conserved residue among highly homologous G protein-coupled receptors is differentially accessible in the binding-site crevice. In addition, this represents the first successful generation of MTSEA-insensitive mutants of mu, delta, and kappa opioid receptors, which will allow determination of residues accessible in the binding-site crevices of these receptors by the substituted cysteine accessibility method.

Amino Acid Sequence↗
PubMed2000

Sensitivity of mature Erbb2 to geldanamycin is conferred by its kinase domain and is mediated by the chaperone protein Hsp90.

ErbB receptors are a family of ligand-activated tyrosine kinases that play a central role in proliferation, differentiation, and oncogenesis. ErbB2 is overexpressed in >25% of breast and ovarian cancers and is correlated with poor prognosis. Although ErbB2 and ErbB1 are highly homologous, they respond quite differently to geldanamycin (GA), an antibiotic that is a specific inhibitor of the chaperone protein Hsp90. Thus, although both mature and nascent ErbB2 proteins are down-regulated by GA, only nascent ErbB1 is sensitive to the drug. To reveal the underlying mechanism behind these divergent responses, we made a chimeric receptor (ErbB1/2) composed of the extracellular and transmembrane domains of ErbB1 and the intracellular domain of ErbB2. The ErbB1/2 protein is functional since its kinase activity was stimulated by epidermal growth factor. The sensitivity of ErbB1/2 to GA was similar to that of ErbB2 and unlike that of ErbB1, indicating that the intracellular domain of the chimera confers GA sensitivity. This finding also suggests that the GA sensitivity of mature ErbB2 depends on cytosolic Hsp90, rather than Grp94, a homolog of Hsp90 that is restricted to the lumen of the endoplasmic reticulum, although both chaperones bind to and are inhibited by GA. Lack of Grp94 involvement in mediating ErbB2 sensitivity to GA is further suggested by the fact that a GA derivative with low affinity for Grp94 efficiently depleted ErbB2 protein in treated cells. To localize the specific region of ErbB2 that confers GA sensitivity, we made truncated receptors with progressive deletions of the cytoplasmic domain and tested the GA sensitivity of these molecules. We found that ErbB2 constructs containing an intact kinase domain retained GA sensitivity, whereas those lacking the kinase domain (ErbB2/DK) lost responsiveness to GA completely. Hsp90 co-immunoprecipitated with all ErbB2 constructs that were sensitive to GA, but not with ErbB2/DK or ErbB1. Both tyrosine-phosphorylated and non-phosphorylated ErbB2 proteins were similarly sensitive to GA, as was a kinase-dead ErbB2 mutant. These data suggest that Hsp90 uniquely stabilizes ErbB2 via interaction with its kinase domain and that GA stimulates ErbB2 degradation secondary to disruption of ErbB2/Hsp90 association.

Amino Acid Sequence↗