Biomedical subjects

W Yu

Publications and source records attributed to W Yu.

At least 163 records · Page 9Linked to original sources

PubMed1999

[Bone mineral analysis of whole body in 292 normal subjects assessed by dual X-ray absorptiometry].

OBJECTIVE: To understand whole body bone mineral changes in normal subjects. METHODS: Bone mineral was measured by dual X-ray absorptiometry (DXA) in 292 normal subjects aged 10-79, including 152 females and 140 males. They were divided into age-groups by decade. RESULTS: In males, peak value ages of total bone mineral content(TBMC), total bone mineral density(TBMD), anteroposterior spine BMD(L2-4 BMD) were in the 30-39, 20-39, 20-29 age-groups respectively. In females, they were all in the 30-39 age-group. Peak values of TBMC, TBMD, L2-4BMD were higher in males than those in females. Loss of bone mineral for females was more pronounced than that for males. There was a tendency of increased BMD among the 70-79 age-group for males. Loss of L2-4 BMD was more pronounced than TBMD. CONCLUSIONS: This study provides the normal bone mineral data of whole body for males and females, and the characteristic of changes.

Absorptiometry, Photon↗

PubMed1998

Preparation, Characterization, and Catalytic Properties of Polymer-Stabilized Ruthenium Colloids.

Poly(N-vinyl-2-pyrrolidone) (PVP)-stabilized ruthenium colloids were prepared by NaBH4 reduction at room temperature and characterized by transmission electron microscopy and x-ray photoelectron spectra. The average diameters of the colloids were 1.3-1.8 nm with final sigma = 0.4-0.7 nm with respect to the preparation conditions. The PVP-stabilized ruthenium colloids were used as catalysts in the hydrogenations of cyclooctene and n-heptene and the selective hydrogenation of citronellal to citronellol. Copyright 1998 Academic Press.

Journal Article↗

PubMed1998

5-oxo-ETE induces pulmonary eosinophilia in an integrin-dependent manner in Brown Norway rats.

We have shown previously that the 5-lipoxygenase product 5-oxo-6,8, 11,14-eicosatetraenoic acid (5-oxo-ETE) is a highly potent eosinophil chemoattractant in vitro. To determine whether this substance can induce pulmonary eosinophil infiltration in vivo, it was administered to Brown Norway rats by tracheal insufflation. Eosinophils were then counted in lung sections that had been immunostained with an antibody to eosinophil major basic protein. 5-Oxo-ETE induced a dramatic increase in the numbers of eosinophils (ED50, 2.5 microg) around the walls of the airways, which reached maximal levels (five times control levels) between 15 and 24 h after administration, and then declined. LTB4 also induced pulmonary eosinophil infiltration with a similar ED50 but appeared to be somewhat less effective. In contrast, LTD4 and LTE4 were inactive. 5-Oxo-ETE-induced eosinophilia was unaffected by the LTB4 and PAF antagonists LY255283 and WEB 2170, respectively. However, it was inhibited by approximately 75% by monoclonal antibodies to CD49d (VLA-4) or CD11a (LFA-1) but was not significantly affected by an antibody to CD11b (Mac-1). In conclusion, 5-oxo-ETE induces pulmonary eosinophilia in Brown Norway rats, raising the possibility that it may be a physiological mediator of inflammation in asthma.

Animals↗

PubMed1998

Soluble CD14(1-152) confers responsiveness to both lipoarabinomannan and lipopolysaccharide in a novel HL-60 cell bioassay.

CD14 is a pattern recognition receptor involved in the interaction with multiple ligands, including LPS from gram-negative bacteria and lipoarabinomannan (LAM) from mycobacteria. While the interactions between LPS and soluble CD14 (sCD14) have been analyzed in detail, LAM/CD14 interactions remain uncharacterized due to the lack of suitable functional assays. We describe herein a novel bioassay for the analysis of CD14/ligand interactions. CD14-negative myeloid HL-60 cells up-regulate endogenous CD14 gene expression when stimulated with LPS in the presence of recombinant soluble CD14(1-348). Using the HL-60 bioassay, we showed that sCD14(1-348) confers responsiveness not only to LPS, but also to LAM. The response to LAM, but not that to LPS, was highly dependent on LPS binding protein (LBP). The N-terminal half of CD14 was sufficient to mediate HL-60 responses to LAM, since HL-60 cells responded with similar efficiency when stimulated with LAM and LBP in the presence of sCD14(1-348) or sCD14(1-152). Thus, the N-terminal 152 amino acids of CD14 contain the site(s) involved in the interaction with LAM and LBP, as well as the residues required for LAM-dependent CD14 signaling.

Gene Expression Regulation↗

PubMed1998

Human ARHGDIG, a GDP-dissociation inhibitor for Rho proteins: genomic structure, sequence, expression analysis, and mapping to chromosome 16p13.3.

GDP-dissociation inhibitors (GDIs) play a primary role in modulating the activity of GTPases. We recently reported the identification of a new GDI for the Rho-related GTPases named RhoGDIgamma. This gene is now designated ARHGDIG by HUGO. Here, in a detailed analysis of tissue expression of ARHGDIG, we observe high levels in the entire brain, with regional variations. The mRNA is also present at high levels in kidney and pancreas and at moderate levels in spinal cord, stomach, and pituitary gland. In other tissues examined, the mRNA levels are very low (lung, trachea, small intestine, colon, placenta) or undetectable. RT-PCR analysis of total RNA isolated from exocrine pancreas and islets shows that the gene is expressed in both tissues. We also report the genomic structure of ARHGDIG. The gene spans over 4 kb and is organized into six exons and five introns. The upstream region lacks a canonical TATA box and contains several putative binding sites for ubiquitous and tissue-specific factors active in central nervous system development. Using FISH, we have mapped the gene to chromosome band 16p13.3. This band is rich in deletion mutants of genes involved in several human diseases, notably polycystic kidney disease, alpha-thalassemia, tuberous sclerosis, mental retardation, and cancer. The promoter structure and the chromosomal location of RhoGDIgamma suggest its importance and underscore the need for further investigation into its biology.

Base Sequence↗

PubMed1998

A study of sexual behavior among rural residents of China.

OBJECTIVE: Although the recent spread of HIV/AIDS and other sexually transmitted diseases (STDs) in China has been associated with sexual activities, little information has been available about sexual behavior in rural areas with high HIV prevalence. Studies identifying high-risk sexual behaviors are needed to formulate effective prevention programs. METHODS: A cross-sectional study design was used to measure sexual activities using a two-stage cluster sampling method. A two-part anonymous questionnaire was used. Sensitive questions related to sexual behavior were administered using a tape recorder, earphones, and an answer sheet which did not include the text. RESULTS: In total, 1057 subjects were interviewed. Among 886 sexually active individuals, 7.8% had >1 sexual partner, 22.8% had premarital sex, 2.4% had anal intercourse, 4.1% had oral intercourse, and 2.3% had both anal and oral intercourse. Less than 2% reported past or current sexually transmitted diseases. Overall, 10.4% used condoms; only 11.2% for every sexual act. History of premarital and extramarital sex was higher in younger people. CONCLUSIONS: Sexual norms in rural China are changing rapidly and high-risk sexual behavior among young rural residents is increasing. Strategies to prevent HIV/AIDS should include education to promote delayed onset of sexual activity, safer sexual behavior, and condom use.

Adolescent↗

PubMed1998

Requirement for specific proteases in cancer cell intravasation as revealed by a novel semiquantitative PCR-based assay.

Proteases are crucial for cancer metastasis, but due to lack of assays, their role in intravasation has not yet been tested. We have developed a human Alu sequence PCR-based assay to quantitate intravasated cells in an in vivo model. We demonstrated that metalloproteinases (MMPs), and most likely MMP-9, are required for intravasation by showing that marimastat, an inhibitor of MMPs, reduced intravasation by more than 90%, and that only tumor cell lines expressing MMP-9 intravasated. Cells with low surface urokinase plasminogen activator (uPA) and uPA receptor (uPAR) were also incapable of intravasation, despite the presence of high levels of MMP-9. We concluded that breaching of the vascular wall is a rate-limiting step for intravasation, and consequently for metastasis, and that cooperation between uPA/uPAR and MMP-9 is required to complete this step.

Allantois↗

PubMed1998

TGF-beta1 effects on proliferation of rat intestinal epithelial cells are due to inhibition of cyclin D1 expression.

Transforming growth factor-beta 1 (TGF-beta1) arrests intestinal epithelial cells (RIE-1 and IEC-6) in the G1 phase of the cell cycle and inhibits cyclin D1 expression. This report describes experiments designed to elucidate the mechanism of cyclin D1 inhibition and to determine whether inhibition of cyclin D1 expression is the cause, rather than the result, of TGF-beta1-mediated cell cycle arrest. TGF-beta1 inhibition of IEC-6 cell proliferation was associated with a decrease in the abundance of cyclin D1/Cdk4 complexes and a corresponding decrease in Cdk4-dependent phosphorylation of the retinoblastoma protein. Metabolic labeling studies indicated that TGF-beta1 inhibited cyclin D1 synthesis without altering the rate of cyclin D1 protein degradation. Cyclin D1 antisense oligonucleotides blocked serum-stimulated induction of cyclin D1 and DNA synthesis, whereas cyclin D1 sense oligonucleotides had no effect. RIE-1 cells were engineered to overexpress human cyclin D1 under the control of a tetracycline-repressible promoter. These cells entered S phase in the presence of TGF-beta1 only when human cyclin D1 was derepressed by the withdrawal of tetracycline. These data indicate that TGF-beta1 inhibits the synthesis of cyclin D1 in gut epithelial cells and that this inhibition is the cause, rather than the result, of TGF-beta1-mediated arrest of intestinal epithelial cell proliferation.

Animals↗

PubMed1998

Dextromethorphan potentiates the effect of morphine in rats with peripheral neuropathy.

Neuropathic pain responds poorly to opioids. We now report that combination of systemic morphine (2 mg/kg) and dextromethorphan (45 mg/kg), a clinically available antitussive with NMDA-antagonist properties, markedly alleviated mechanical and cold allodynia-like behavior in a rat model of peripheral mononeuropathy. Neither drug produced a significant effect on its own at these doses. The anti-allodynic effect of morphine plus dextromethorphan was reversed by naloxone. The present results suggest that a combination of NMDA-antagonist and opiates might be effective in treating neuropathic pain. Furthermore, the effect of this drug combination is mainly mediated via opioid receptors.

Analgesics, Opioid↗

PubMed1998

Distinct functional stoichiometry of potassium channel beta subunits.

Shaker-type potassium channels play important roles in determining the electrical excitability of cells. The native channel complex is thought to be formed by four pore-forming alpha subunits that provide four interaction sites for auxiliary modulatory Kvbeta subunits. Because Kvbeta subunits possess diverse modulatory activities including either up-regulation or down-regulation of potassium currents, differential assembly of the alpha-beta complex could give rise to diverse current properties. However, the detailed physical and functional stoichiometry of the alpha-beta complex remains unknown. Kvbeta1 subunits reduce potassium currents through inactivation, whereas Kvbeta2 subunits enhance potassium currents by inhibiting the Kvbeta1-mediated inactivation and at the same time by promoting the surface expression of certain potassium channels. In this report we show that Kvbeta1 and Kvbeta2 of the Shaker-type potassium channels display distinct functional stoichiometry to interact with the Kv1 alpha subunits, a subfamily of Shaker-type potassium channels. The interaction of Kvbeta1 subunits with alpha subunits is consistent with the alpha4betan model, where n equals 0, 1, 2, 3, or 4, depending upon the relative concentration of alpha and beta subunits. The alpha4betan stoichiometry allows for gradual changes of the Kvbeta1-mediated inactivation. In contrast, Kvbeta2 subunits self-associate to form oligomers and interact with the alpha subunits via alpha4beta4 stoichiometry, which permits effective multivalent associations with alpha subunits. Such distinct functional stoichiometry of Kvbeta1 and Kvbeta2 provides a molecular mechanism that is well suited to their contrasting activities of up-regulation or down-regulation of potassium currents.

Animals↗

PubMed1998

Isomeric differentiation of asparagine-linked oligosaccharides by matrix-assisted laser desorption-ionization postsource decay time-of-flight mass spectrometry.

Matrix-assisted laser desorption-ionization (MALDI)-postsource decay (PSD) was used to differentiate glycoprotein-released N-linked oligosaccharide isomers directly from aliquots of glycosidase digests and peak fractions collected from high-pH anion exchange chromatography (HPAEC) with minimal sample handling and material. With the implementation of instrumental tuning and acquisition controls, MALDI-PSD of NMR-characterized high-mannose, hybrid, and complex standards resulted in spectra with reproducible fragment ion peak intensity ratios which correlated well to the respective oligosaccharide branching patterns. A "knowledge-based" strategy was utilized to characterize unknown isomeric N-glycan structures in which specific fragment ion types and their distributions in the unknown PSD spectrum were compared to those in PSD spectra of standards possessing similar structural features. This PSD knowledge-based isomeric differentiation strategy was applied to distinguishing recombinant glycoprotein-derived Man7 D1 versus D2/D3 isomers directly from a PNGaseF digest aliquot of high-mannose N-glycans based on branching differences. A precursor ion selection device was employed to isolate the component of interest from the mass profile without additional chromatographic isolation steps. MALDI-MS signal-to-background was maximized for direct PSD with on-the-probe sample clean-up methods. The asialo complex N-glycan PSD knowledge base was used to differentiate HPAEC peak fractions containing the tri- and tri'-antennary branching isomers and two tetraantennary isomers with antennal versus core fucose locations. Although the particular asialo complex N-glycan isomers here were well separated by HPAEC, MALDI-MS alerted us to their presence using m/z-derived monosaccharide compositions and PSD fragmentation allowed us to differentiate these structures using the HPAEC elution positions as guides.

Asparagine↗

PubMed1998

Regulation of the MAP kinase pathway by mammalian Ksr through direct interaction with MEK and ERK.

BACKGROUND: Genetic screens in Drosophila melanogaster and Caenorhabditis elegans identified the kinase suppressor of Ras, Ksr, as a new component in the Ras intracellular signaling pathway. In these organisms, mutations in Ksr resulted in attenuation of Ras-mediated signaling. Homologs of Ksr have also been isolated from mice and humans; their precise role in Ras signaling is not well defined. Here, we present data showing interactions between the murine form of Ksr (mKsr-1) and other components of the Ras pathway. RESULTS: To gain insight into the biological function of Ksr, we used a yeast two-hybrid screen and found an interaction between the carboxy-terminal region of mKsr-1 and mitogen-activated protein (MAP) kinase kinase 1 (MAPKK-1 or MEK-1). An interaction was also detected between MAP kinase (also called extracellular signal-regulated kinase; ERK), and the amino-terminal region of mKsr-1. These interactions were recapitulated in COS-7 cells. Further, when COS-7 cells were transfected with either full-length mKsr-1 or only its carboxy-terminal region, an inhibition of serum-stimulated MAP kinase activation was observed. Microinjection of full-length mKsr-1 or its carboxy-terminal, but not its amino-terminal region, blocked serum-induced DNA synthesis in rat embryo fibroblasts. Co-injection of mKsr-1 with MEK-1 reversed the blockade. CONCLUSIONS: Together with the data from genetic analyses, our findings lead us to propose that mKsr-1 may control MAP kinase signaling by serving as a scaffold protein that links MEK and its substrate ERK.

Amino Acid Sequence↗

PubMed1998

Pathways for eosinophil lipid body induction: differing signal transduction in cells from normal and hypereosinophilic subjects.

Although lipid bodies, inducible cytoplasmic inclusions active in arachidonic acid metabolism, are abundant in activated leukocytes, including eosinophils, mechanisms for eosinophil lipid body formation are not certain. Eosinophils from hypereosinophilic syndrome (HES) donors contained about twice (approximately 18/cell) as many lipid bodies as eosinophils froin normal donors (approximately 10/cell). By immunocytochemistry both 5- and 15-lipoxygenases were localized at lipid bodies in HES eosinophils. Platelet-activating factor (PAF) induced rapid, receptor-mediated increases in lipid bodies in normal and HES eosinophils. Protein kinase C (PKC) inhibitors, chelerythrine and calphostin C, inhibited PAF-induced lipid body formation partially in normal and HES eosinophils. In HES, but not normal, eosinophils, PAF-induced lipid body formation was completely blocked by two tyrosine kinase inhibitors, herbimycin A and genistein, which were not acting on 5-lipoxygenase because they also blocked 5-HETE-induced lipid body formation in HES, and not normal, eosinophils. After 24 h culture with eosinophil growth factor cytokines [interleukin (IL)-3, IL-5, and granulocyte-macrophage colony-stimulating factor (GM-CSF) or GM-CSF alone but not IL-5 or IL-3 alone], normal eosinophils were induced to exhibit an HES-like phenotype, including increased lipid body numbers and tyrosine kinase-dependent signaling for PAF-induced lipid body formation. Thus, signal transduction mechanisms involved in PAF-induced lipid body formation in eosinophils can be differentially recruited. Tyrosine kinase-dependent signaling is not involved in normal eosinophils, but is active in HES eosinophils and in normal eosinophils cultured with GM-CSF. PKC- and tyrosine kinase-dependent pathways are involved in the formation of eosinophil lipid bodies, which may facilitate enhanced synthesis of lipoxygenase-derived eicosanoids.

Adult↗

PubMed1998

Human dopamine D3 and D2L receptors couple to inward rectifier potassium channels in mammalian cell lines.

The molecular mechanisms coupling the D3 dopamine receptor to downstream effectors have neither been well defined nor well characterized. Here we examine the coupling of the human D3 receptor to G-protein coupled inward rectifier potassium channels (GIRKs) in mammalian cells. Human D3 receptors couple strongly to homomeric human GIRK2 channels coexpressed in Chinese hamster ovary (CHO) cells, with a coupling efficiency comparable to that of D2L receptors. The coupling between D3 receptors and native GIRK channels was examined in an AtT-20 mouse pituitary cell line stably expressing the human D3 receptor. AtT-20 cells endogenously express somatostatin and muscarinic receptors coupled to GIRK channels. RT-PCR and Western blot analyses revealed that AtT-20 cells natively express Kir3.1 and Kir3.2 channel isoforms, but not D2 or D3 dopamine receptors. In D3 receptor expressing AtT-20 cells, application of the D2/D3 receptor agonist, quinpirole, induces pertussis toxin-sensitive inward rectifying K+ currents that are blocked by barium. Activation of D3 receptors leads to both homologous desensitization of this receptor and an unusual unidirectional heterologous desensitization of somatostatin receptors. AtT-20 cells may be a good model to examine the functional role of D3 dopamine receptors in regulating neurotransmitter secretion.

Adenosine Triphosphate↗

PubMed1998

Assays for investigating RNA editing in plant mitochondria.

In plant organelles transcripts are modified posttranscriptionally by RNA editing. This modification process changes almost every protein-coding RNA at specific cytidine and uridine positions. Therefore, mitochondrially encoded protein sequences differ from the genomically fixed information and show, after editing, a higher conservation. To investigate this unusual processing step in plant mitochondria, several assays have been developed. However, compared with the progress made in other RNA editing fields, knowledge about the factors involved in plant mitochondrial editing is limited. One reason for this is the lack of a reliable in vitro system for mitochondria. To reveal the biochemical nature of the RNA editing reaction in plant mitochondria, we developed an in vitro system by which we were able to show that cytidine is specifically modified to uridine by a deamination or transamination process. Here we describe the development of a pea in vitro system and discuss assays to follow the editing process.

Genetic Techniques↗

PubMed1998

Evidence that spinal endogenous opioidergic systems control the expression of chronic pain-related behaviors in spinally injured rats.

We have previously reported that ischemic spinal cord injury in rats leads to chronic pain-related behaviors. Thus, rats exhibited aversive reactions to innocuous mechanical stimuli (mechanical allodynia) applied to a body area at or rostral to the dermatomes innervated by the injured spinal segments. The responses of the rats to cold are also markedly enhanced (cold allodynia). Interestingly, more than 50% of spinally injured rats did not develop these abnormal pain-related behaviors after spinal cord injury. In the present study, we showed that the extent of injury is similar between allodynic and non-allodynic rats. Furthermore, intrathecal (i.t.) naloxone, a broad-spectrum opioid receptor antagonist, reversibly provoked mechanical and cold allodynia-like responses in spinally injured rats that did not develop such behaviors spontaneously. However, naloxone did not elicit such reactions in normal rats and did not alter the tail-flick latency in normal or spinally injured rats. Furthermore, i.t. D-Phe-Cys-Tyr-D-Trp-Orn-Thr-Pen-Thr-NH2 (CTOP) or naltridole, selective antagonists of mu and delta opioid receptors, respectively, also triggered pain-related behaviors similarly to naloxone. Although norbinaltorphimine (nor-BIN), a selective kappa-receptor antagonist, also elicited such responses, the time course of the effect makes it unlikely that spinal kappa-receptors were involved. These results suggested that the expression of abnormal pain-related behaviors in some spinally injured rats is tonically suppressed by the spinal opioidergic system. Interindividual differences that lead to lack or dysfunction of such inhibition may underly the appearence of pain-related behavior in some, but not all, spinally injured rats. It is suggested that such inhibition is exerted through spinal mu and delta, but not kappa, opioid receptors. The endogenous opioidergic control appears to be only active against abnormal painrelated behaviors in spinally injured rats. Our results are relevant for the clinical observation that only a subgroup of patients with nerve injury suffers from neuropathic pain.

Animals↗

PubMed1998

Comparison of radiography, computed tomography and magnetic resonance imaging in the detection of sacroiliitis accompanying ankylosing spondylitis.

OBJECTIVE: To compare magnetic resonance (MR) imaging, computed tomography (CT), and radiography in the detection of sacroiliitis accompanying ankylosing spondylitis (AS). DESIGN AND SUBJECTS: Nine volunteers and 24 patients were recruited. Radiography, CT, and MR imaging were completed within a 1-week period in 24 patients with AS. In precontrast MR examination, spin-echo T1, fast spin-echo T2, and gradient echo with rephasing T2* images were obtained without fat saturation using a 0.3-T imager for all volunteers and patients. Postcontrast MR examination was performed using the same precontrast SE T1 sequence for patients with AS. RESULTS AND CONCLUSIONS: MR imaging directly showed the normal cartilage in all 16 sacroiliac joints of the 8 volunteers. In the 24 patients with AS, cartilage abnormalities were observed in 42 sacroiliac joints. More diagnoses of sacroiliitis were made using MR and CT imaging than using radiography (P < 0.001). Therefore, low-field-strength MR can be useful in detecting early sacroiliitis in patients with AS. MR imaging was able to reveal early cartilage changes and bone marrow edema, which could not be found by either CT or radiography.

Adolescent↗

PubMed1998

Epidemiologic trends in the evaluation and treatment of lower urinary tract symptoms in elderly male Medicare patients from 1991 to 1995.

PURPOSE: We describe utilization of procedures to reveal recent epidemiologic trends in evaluation and management of benign prostatic hyperplasia (BPH). MATERIALS AND METHODS: Medicare claims data reflect clinical practice in the vast majority of elderly Americans. The standard 5% beneficiary sample from Medicare claims files for 1991 to 1995 was searched to identify men 65 years old or older with invoices containing diagnostic and procedure codes indicative of prostate disease or lower urinary tract symptoms. Physician/supplier file claims for this sample of patients were used to identify diagnostic and therapeutic procedures relevant to BPH. RESULTS: During these 5 years claims for uroflowmetry peaked in 1993, filling cystometry gradually declined and pressure flow studies increased. Transurethral resection of the prostate decreased 43%, with even steeper reductions for open prostatectomy. The proportion of transurethral resections performed in hospital inpatients ebbed from 96 to 88%. Age specific operative rates for transurethral resection were highest in the ninth decade, and during the 5 years operative rates generally declined more among white than black men of the same age. Although urethrocystoscopy and excretory urography explicitly for BPH decreased markedly, from 1992 to 1995 the proportion of transurethral resections preceded by urethrocystoscopy for any indication increased from 45 to 47%, while excretory urograms were still obtained before 36% of these operations in 1992 and decreased to 26% in 1995. CONCLUSIONS: Evaluation and treatment of lower urinary tract symptoms in elderly men in the United States changed rapidly between 1991 and 1995, with a sharp decline in invasive therapy for BPH.

Aged↗