Search PubMed⌕ Search

Biomedical subjects

W Wang

Publications and source records attributed to W Wang.

At least 487 records · Page 27Linked to original sources
PubMed2000

Affinity purification and partial characterization of the zonulin/zonula occludens toxin (Zot) receptor from human brain.

The intercellular tight junctions (TJs) of endothelial cells represent the limiting structure for the permeability of the blood-brain barrier (BBB). Although the BBB has been recognized as being the interface between the bloodstream and the brain, little is known about its regulation. Zonulin and its prokaryotic analogue, zonula occludens toxin (Zot) elaborated by Vibrio cholerae, both modulate intercellular TJs by binding to a specific surface receptor with subsequent activation of an intracellular signaling pathway involving phospholipase C and protein kinase C activation and actin polymerization. Affinity column purification revealed that human brain plasma membrane preparations contain two Zot binding proteins of approximately 55 and approximately 45 kDa. Structural and kinetic studies, including saturation and competitive assays, identified the 55-kDa protein as tubulin, whereas the 45-kDa protein represents the zonulin/Zot receptor. Biochemical characterization provided evidence that this receptor is a glycoprotein containing multiple sialic acid residues. Comparison of the N-terminal sequence of the zonulin/Zot receptor with other protein sequences by BLAST analysis revealed a striking similarity with MRP-8, a 14-kDa member of the S-100 family of calcium binding proteins. The discovery and characterization of this receptor from human brain may significantly contribute to our knowledge on the pathophysiological regulation of the BBB.

Amino Acid Sequence↗
PubMed2000

Neural electrophysiological studies on the external anal sphincter in children with anorectal malformation.

BACKGROUND/PURPOSE: Abnormality of innervation of external anal sphincter is one of the most important factors affecting postoperative anorectal function. The abnormalities of lumbosacral nerves have been reported in many radiological and histopathologic studies. There are few reports on the neurophysiological changes in children with anoractal malformation. The aim of this study was to examine the functional changes of nerves to the external anal sphincter in anorectal malformation. METHODS: Forty-five patients with anorectal malformation underwent studies of latencies of pudendo-anal reflex, spinoanal response, and evoked potential of cauda equine simultaneously. The conduction time of afferent nerve, efferent nerve, and sacral spinal center of pudendo-anal reflex arc were analyzed quantitatively. RESULTS: The latencies of pudendo-anal reflex, spino-anal response, and conduction time of sacral spinal center significantly are prolonged in patients with anorectal malformation (P< .05). There was significant difference between rectourethral fistula group and vestibular fistula group as well as low-type deformity group. The patients with lumbosacral anomalies such as lumbosacral spinal bifida or absence of S4 or S5 had prolonged latencies, especially the pudendo-anal reflex latency. There was significant negative correlation between the latencies and clinical scores. Although pudendoanal reflex latency was longer in patients who had posterior sagittal anorectoplasty than those who had abdominoperineal pull-through procedure, the difference was not significant. CONCLUSIONS: The abnormality of nerves to external anal sphincters is one of the important causes for clinical outcome. The neural lesions vary in each type of anal and lumbosacral deformity.

Adolescent↗
PubMed2000

Provision of rhIGF-I/IGFBP-3 complex attenuated development of cancer cachexia in an experimental tumor model.

UNLABELLED: Tumor growth is associated with development of cachexia which includes progressive wasting and anorexia. Our previous studies have indicated that insulin like growth factor-I (rhIGF-I) in complex with its binding protein 3 (IGFBP 3), but not free IGF-I, was a potent stimulator of muscle protein synthesis in rats with chronic undernutrition. The aim of the present study was to evaluate the effect of rhIGF-I/IGFBP-3 on the development of cancer cachexia, and to assess safety data on net tumor growth and progression during treatment. METHODS: A methylcholantrene induced sarcoma was implanted s.c. in C 57 bl mice. The animals were provided with rhIGF-I/rhIGFBP-3 (5 microg/g bw) i.v. twice daily (n= 18). Controls were provided with saline (n= 20). Body weight and food intake were registered daily. Net tumor growth was measured over 10 days. Protein synthesis in liver and muscle, as well as plasma concentrations of glucose, insulin, IGF-I and amino acids were measured at the end of the study. RESULTS: tumor size did not differ between control mice and rhIGF-I/rhIGFBP-3 treated mice (1.5 +/- 0.1 g wet tumor weight vs 1.6 +/- 0.2 g respectively). Saline treated tumor bearing controls lost 9.1 +/- 1.3 % body weight over 10 days due to rapid tumor growth while rhIGF-I/rhIGFBP-3 provision attenuated weight loss to 5.6 +/- 1.3% of body weight in study mice (P< 0.05). Food intake was improved and blood glucose concentration was reduced from 7.1 +/- 0.5 to 5.8 +/- 0.2 (P< 0.05) in response to treatment. CONCLUSION: Our results demonstrate that rhIGF-I/rhIGFBP-3 complex did not affect net tumor growth. Moreover rhIGF-I/rhIGFBP-3 complex improved tumor-host nutritional state by improving food intake, attenuating weight loss and improving glucose metabolism.

Animals↗
PubMed2000

Persimmon leaf extract and astragalin inhibit development of dermatitis and IgE elevation in NC/Nga mice.

BACKGROUND: We previously found that persimmon leaf extract contains antiallergic substances that inhibit histamine release by human basophilic cell line KU812 in response to cross-linkage of FcepsilonRI. OBJECTIVES: The purpose of this study was to identify substances in the persimmon leaf extract that are responsible for the effect and to examine their in vivo effects on the allergic mouse model. METHODS: HPLC analysis of persimmon leaf extract was done to measure its content. Inhibitory activity of persimmon leaf extract or its major constituent of flavonoids (astragalin) on the histamine release by KU812 cells was examined. To investigate the effects of these substances in vivo, models of passive cutaneous anaphylaxis and atopic dermatitis mice (NC/Nga) were used. RESULTS: Persimmon leaf extract or astragalin inhibited histamine release from KU812 in response to cross-linkage of FcepsilonRI. Oral intake of both substances dose dependently inhibited passive cutaneous reactions. Moreover, oral administration of these substances to NC/Nga atopic dermatitis-model mice led to a striking suppression of the development of dermatitis, scratching behavior, and serum IgE elevation. Histologic analyses revealed that infiltration of inflammatory cells, especially degranulated mast cells, thickening of the epidermis, and prominent hyperkeratosis, were significantly reduced. Immunologic studies showed that the capacity of spleen T cells to produce both IL-4 and IL-13, but not IFN-gamma, was downregulated by means of oral intake of these substances. CONCLUSION: This study demonstrates a novel activity of astragalin and the dramatic effect of persimmon leaf extract and astragalin on atopic dermatitis-model mice.

Administration, Oral↗
PubMed2000

Extracellular ATP inhibits the small-conductance K channel on the apical membrane of the cortical collecting duct from mouse kidney.

We have used the patch-clamp technique to study the effects of changing extracellular ATP concentration on the activity of the small-conductance potassium channel (SK) on the apical membrane of the mouse cortical collecting duct. In cell-attached patches, the channel conductance and kinetics were similar to its rat homologue. Addition of ATP to the bathing solution of split-open single cortical collecting ducts inhibited SK activity. The inhibition of the channel by ATP was reversible, concentration dependent (K(i) = 64 microM), and could be completely prevented by pretreatment with suramin, a specific purinergic receptor (P(2)) blocker. Ranking of the inhibitory potency of several nucleotides showed strong inhibition by ATP, UTP, and ATP-gamma-S, whereas alpha, beta-Me ATP, and 2-Mes ATP failed to affect channel activity. This nucleotide sensitivity is consistent with P(2)Y(2) purinergic receptors mediating the inhibition of SK by ATP. Single channel analysis further demonstrated that the inhibitory effects of ATP could be elicited through activation of apical receptors. Moreover, the observation that fluoride mimicked the inhibitory action of ATP suggests the activation of G proteins during purinergic receptor stimulation. Channel inhibition by ATP was not affected by blocking phospholipase C and protein kinase C. However, whereas cAMP prevented channel blocking by ATP, blocking protein kinase A failed to abolish the inhibitory effects of ATP. The reduction of K channel activity by ATP could be prevented by okadaic acid, an inhibitor of protein phosphatases, and KT5823, an agent that blocks protein kinase G. Moreover, the effect of ATP was mimicked by cGMP and blocked by L-NAME (N(G)-nitro-l-arginine methyl ester). We conclude that the inhibitory effect of ATP on the apical K channel is mediated by stimulation of P(2)Y(2) receptors and results from increasing dephosphorylation by enhancing PKG-sensitive phosphatase activity.

Adenosine Triphosphate↗
PubMed2000

Inhibition of metabolic activity in papillary thyroid carcinoma by a somatostatin analogue.

Two patients with widely metastatic papillary thyroid cancer demonstrated progressive growth of diffuse pulmonary lesions. One patient had no apparent response to high doses of 131I and the other hand no 131I uptake. 111In-pentetreotide scans revealed that many of the metastatic lesions expressed somatostatin receptors. The baseline metabolic activity and three-dimensional volume of the lesions were determined by 18F-fluoro-de-oxyglucose positron emission tomography (FDG-PET). After 3 or 4 months of octreotide (Sandostatin LAR Depot; Novartis Pharmaceutical, East Hanover, NJ) therapy, repeat FDG-PET scans revealed reductions in tumor volume and decreases in the standard uptake values of FDG. We conclude that octreotide therapy can change the biological activity of metastatic thyroid cancer lesions that exhibit somatostatin receptors.

Antineoplastic Agents, Hormonal↗
PubMed2000

Psychosocial predictors of smoking among secondary school students in Henan, China.

The objective of this study was to measure the risk factors associated with tobacco use among secondary school students in Henan, China. Self-reported questionnaires were administered to four secondary schools; 3519 students were studied including 1799 boys and 1720 girls aged 10-19. Demographic, behavioral, attitudinal/belief, knowledge and interpersonal variables were investigated. Overall, 15.1% of boys and 1.4% girls reported smoking at least occasionally. Smoking onset is most prevalent from the ages of 10-14. The smoking rate increased with age. The likelihood of tobacco use was significantly higher among those having peers, teachers or mother who smoked. Positive smoking-related attitudes among students had a significant association with their smoking status. The results suggest that effective smoking prevention interventions need to be comprehensive and implemented in the early teen years.

Adolescent↗
PubMed2000

Rapid determination of zygosity and common aneuploidies from amniotic fluid cells using quantitative fluorescent polymerase chain reaction following genetic amniocentesis in multiple pregnancies.

Following second-trimester twin amniocentesis, we used quantitative fluorescent polymerase chain reaction (QF-PCR) assays and polymorphic small tandem repeats (STR) for rapid determination of zygosity and common aneuploidies from amniotic fluid (AF) cells in four pregnancies with like-sex twins, fused placentae and inconclusive chorionicity. The first and the second cases were suspected to have inadvertent sampling of the same amniotic cavity twice. The first case showed a dizygotic (DZ) pattern and repeat amniocentesis was thus avoided. The second case was monozygotic (MZ) and was complicated by discordant fetal growth and twin-twin transfusion syndrome. The third case was associated with a co-twin malformation, occipital encephalocele. DNA studies revealed MZ twinning with a discordant structural defect. The fourth case was associated with co-twin abnormalities of cystic hygroma and hydrops fetalis. DNA studies showed DZ twinning with discordant structural and chromosomal defects. The QF-PCR assay with STR has the advantages of rapid determination of zygosity and common aneuploidies in AF cells. This simple test appears to be useful in the instances of possible inadvertent puncture of the same amniotic cavity twice during amniocentesis and of discordant fetal structural and/or chromosomal abnormalities following genetic amniocentesis in multiple pregnancies with uncertain chorionicity.

Adult↗
PubMed2000

Dietary soy protein is associated with reduced intestinal mucosal polyamine concentration in male Wistar rats.

Quantitation of polyamine levels has been correlated with biomarkers of proliferation in the colon mucosa where dysregulated epithelial hyperproliferation is associated with colorectal cancer risk. This study was performed to assess the response of polyamine measurements to dietary factors in an animal model. Male Wistar rats were fed purified diet or diets substituted by 20% lard fat, 20% beet fiber and 20% soy protein. After 2 wk, mucosal polyamines were measured along intestinal tracts by HPLC. In rats fed the control diet (n = 10), mucosal polyamines were found at high levels in the duodenum, jejunum and ileum but at low levels in the cecum, colon and rectum. Compared with rats fed the control diet, those fed the 20% lard diet showed greater polyamine levels in the large intestine (P < 0.05, n = 10), but those fed the 20% fiber diet exhibited lower polyamine levels in the small intestine (P < 0.05, n = 9). However, rats fed the 20% soy protein diet had lower polyamine levels in both small and large intestines (P < 0.05, n = 15). Significant linear correlations were observed between rectal polyamine levels and the dietary energy intakes in these four diet groups (r = 0.972-0.991, P < 0.001). Supplementation of 0.1% soy isoflavones to the basal diet or 0.3% DL-methionine to the 20% soy protein diet for 4 wk did not affect polyamine levels. The results indicate that soy protein reduced mucosal polyamine levels, at least in part, through reduction of energy intakes. Further studies are warranted to verify that polyamine levels in intestinal mucosa are useful as an intermediate endpoint of the dietary risk factors.

Animals↗
PubMed2000

The origin of the Jingwei gene and the complex modular structure of its parental gene, yellow emperor, in Drosophila melanogaster.

Jingwei (jgw) is the first gene found to be of sufficiently recent origin in Drosophila to offer insights into the origin of a gene. While its chimerical gene structure was partially resolved as including a retrosequence of alcohol dehydrogenase (ADH:), the structure of its non-ADH: parental gene, the donor of the N-terminal domain of jgw, is unclear. We characterized this non-ADH: parental locus, yellow emperor (ymp), by cloning it, mapping it onto the polytene chromosomes, sequencing the entire locus, and examining its expression patterns in Drosophila melanogaster. We show that ymp is located in the 96-E region; the N-terminal domain of ymp has donated the non-ADH: portion of jgw via a duplication. The similar 5' portions of the gene and its regulatory sequences give rise to similar testis-specific expression patterns in ymp and jgw in Drosophila teissieri. Furthermore, between-species comparison of ymp revealed purifying selection in the protein sequence, suggesting a functional constraint in ymp. While the structure of ymp provides clear information for the molecular origin of the new gene jgw, it unexpectedly casts a new light on the concept of genes. We found, for the first time, that the single locus of the ymp gene encompasses three major molecular mechanisms determining structure of eukaryotic genes: (1) the 5' exons of ymp are involved in an exon-shuffling event that has created the portion recruited by jgw; (2) using alternative cleavage sites and alternative splicing sites, the 3' exon groups of ymp produce two proteins with nonhomologous C-terminal domains, both exclusively in the testis; and (3) in the opposite strand of the third intron of ymp is an essential gene, musashi (msi), which encodes an RNA-binding protein. The composite gene structure of ymp manifests the complexity of the gene concept, which should be considered in genomic research, e.g., gene finding.

Alternative Splicing↗
PubMed2000

Rapid and parallel chromosomal number reductions in muntjac deer inferred from mitochondrial DNA phylogeny.

Muntjac deer (Muntiacinae, Cervidae) are of great interest in evolutionary studies because of their dramatic chromosome variations and recent discoveries of several new species. In this paper, we analyze the evolution of karyotypes of muntjac deer in the context of a phylogeny which is based on 1,844-bp mitochondrial DNA sequences of seven generally recognized species in the muntjac subfamily. The phylogenetic results support the hypothesis that karyotypic evolution in muntjac deer has proceeded via reduction in diploid number. However, the reduction in number is not always linear, i.e., not strictly following the order: 46-->14/13-->8/9-->6/7. For example, Muntiacus muntjak (2n = 6/7) shares a common ancestor with Muntiacus feae (2n = 13/14), which indicates that its karyotype was derived in parallel with M. feae's from an ancestral karyotype of 2n >/= 13/14. The newly discovered giant muntjac (Muntiacus vuquangensis) may represent another parallel reduction lineage from the ancestral 2n = 46 karyotype. Our phylogenetic results indicate that the giant muntjac is relatively closer to Muntiacus reevesi than to other muntjacs and may be placed in the genus Muntiacus Analyses of sequence divergence reveal that the rate of change in chromosome number in muntjac deer is one of the fastest in vertebrates. Within the muntjac subfamily, the fastest evolutionary rate is found in the Fea's lineage, in which two species with different karyotypes diverged in around 0.5 Myr.

Animals↗
PubMed2000

Differential gene expression detected by suppression subtractive hybridization in the ethylene glycol monomethyl ether-induced testicular lesion.

The solvent ethylene glycol monomethyl ether (EGME) produces the same testicular lesions in rodents and human testis cultures, whose onset is characterized by apoptosis of pachytene spermatocytes. To identify gene changes early in the lesion and determine the possible involvement of cells other than the spermatocytes, we employed a suppression subtractive hybridization technique using whole testes from mice treated 8 h previously with 500 mg/kg EGME to generate two subtracted mouse testis cDNA libraries enriched for gene populations either up-regulated or down-regulated by EGME. A total of 70 clones were screened, and 6 of them were shown by Northern blotting to be differentially expressed in the EGME lesion. The three clones with increased expression after EGME treatment were identical to t-complex testis expressed gene 1 (tctex1), a gene encoding ribosomal protein S25, and a heretofore uncharacterized mouse testis expressed sequence tag. Three other genes suppressed by EGME were tctex2, alpha-2,6-sialyltransferase gene, and another uncharacterized mouse testis expressed sequence tag. Predicted peptide sequences of these clones contain multiple motifs for phosphorylation, glycosylation, and myristoylation. In situ hybridization with the antisense RNA probes further supported the expression changes of these six clones and localized the changes in multiple germ cell stages as well as other cell types (Sertoli, interstitial and peritubular cells). These data at the gene expression level are the first to demonstrate the early involvement in this lesion of cell types other than the dying spermatocytes.

Amino Acid Motifs↗
PubMed2000

Septic mucosal intraepithelial lymphoid immune suppression: role for nitric oxide not interleukin-10 or transforming growth factor-beta.

OBJECTIVE: Recent studies indicate that sepsis induces a marked depression in the splenocyte immune response (as illustrated by decreased interleukin [IL]-2 production, interferon [IFN]-gamma production, or both) in response to T-cell mitogen. However, it is not known whether a similar depression is evident in the phenotypically distinct, small intestine intraepithelial lymphocytes (IELs) or what regulates this process during sepsis. Because the maintenance of a competent mucosal immune response is thought to be central to the animal's ability to survive sepsis, we attempted to determine whether IEL's IL-2/IFN-gamma production is suppressed and what mediates this depression. RESULTS: Our studies indicated that C3H/HeN mice subjected to cecal ligation and puncture (CLP) exhibited a marked decline in the ability of IELs to release IL-2/IFN-gamma at 24 hours and that this decline is associated with increased secretion of IL-10 and nitric oxide (NO). To the extent that IL-10 accounted for this loss of IL-2/IFN-gamma release, we observed that IL-10 gene deficiency neither restored the IL-2/IFN-gamma release nor suppressed the increase in NO when compared with background control, C57BL/6J mouse cells. To further study whether NO was involved in this immune suppression, iNOS knockout (iNOS -/-) were also subjected to the same procedure; however, the depression in IL-2/IFN-gamma was not seen in iNOS -/- mice when compared with background controls. CONCLUSION: Our data indicate that IL-10, which affects splenic lymphoid response, may not be a key mediator of IEL immune suppression and that the induction of NO may play a more significant role in gastrointestinal immune dysfunction seen in late sepsis.

Animals↗
PubMed2000

Modeling study on the validity of a possibly simplified representation of proteins.

The folding characteristics of sequences reduced with a possibly simplified representation of five types of residues are shown to be similar to their original ones with the natural set of residues (20 types or 20 letters). The reduced sequences have a good foldability and fold to the same native structure of their optimized original ones. A large ground state gap for the native structure shows the thermodynamic stability of the reduced sequences. The general validity of such a five-letter reduction is further studied via the correlation between the reduced sequences and the original ones. As a comparison, a reduction with two letters is found not to reproduce the native structure of the original sequences due to its homopolymeric features.

Amino Acid Sequence↗
PubMed2000

Perturbation theory for the kink of the sine-gordon equation

A singular perturbation theory is developed to investigate the kink propagating in systems governed by the sine-Gordon equation with perturbations. The outstanding characteristic of the present theory lies in that the dynamic equation and the dispersive wave as well as the "translation mode" are consistently determined in a natural manner, involving no sophisticated derivations pertaining to the inverse scattering transform. A distinct and strict linearization for the subject is introduced. Some notable cases are reformulated by the theory.

Journal Article↗
PubMed2000

Receptor density and recycling affect the rate of agonist-induced desensitization of mu-opioid receptor.

Previously, we reported that the time course for the rapid phosphorylation rate of mu-opioid receptor expressed in human embryonic kidney (HEK)293 cells did not correlate with the slow receptor desensitization rate induced by [D-Ala(2),N-MePhe(4), Gly-ol(5)]-enkephalin (DAMGO). However, others have suggested that receptor phosphorylation is the trigger for mu-opioid receptor desensitization. In this study, we demonstrated the relatively slow rate of receptor desensitization could be attributed partially to the recycling of internalized receptor as determined by fluorescence-activated cell-sorting analysis. However, the blockade of the endocytic and Golgi transport events in HEK293 cells with monensin and brefeldin A did not increase the initial rate of receptor desensitization. But the desensitization rate was increased by reduction of the mu-opioid receptor level with beta-furnaltrexamine (betaFNA). The reduction of the receptor level with 1 microM betaFNA significantly increased the rate of etorphine-induced receptor desensitization. By blocking the ability of receptor to internalize with 0.4 M sucrose, a significant degree of receptor being rapidly desensitized was observed in HEK293 cells pretreated with betaFNA. Hence, mu-opioid receptor is being resensitized during chronic agonist treatment. The significance of resensitization of the internalized receptor in affecting receptor desensitization was demonstrated further with human neuroblastoma SHSY5Y cells that expressed a low level of mu-opioid receptor. Although DAMGO could not induce a rapid desensitization in these cells, in the presence of monensin and brefeldin A, DAMGO desensitized the mu-opioid receptor's ability to regulate adenylyl cyclase with a t(1/2) = 9.9 +/- 2.1 min and a maximal desensitized level at 70 +/- 4.7%. Furthermore, blockade of receptor internalization with 0.4 M sucrose enhanced the DAMGO-induced receptor desensitization, and the inclusion of monensin prevented the resensitization of the mu-opioid receptor after chronic agonist treatment in SHSY5Y cells. Thus, the ability of the mu-opioid receptor to resensitize and to recycle, and the relative efficiency of the receptor to regulate adenylyl cyclase activity, contributed to the observed slow rate of mu-opioid receptor desensitization in HEK293 cells.

Brefeldin A↗
PubMed2000

Dopamine transporter tryptophan mutants highlight candidate dopamine- and cocaine-selective domains.

Cocaine blocks the normal role of the dopamine transporter (DAT) in terminating dopamine signaling and in restricting its spatial spread through molecular interactions that remain largely obscure. Cocaine analog structure-activity studies suggest roles for cationic and hydrophobic interactions between DAT, dopamine, cocaine, and the sodium and chloride ions whose gradients power uptake processes. Tryptophan residues lying in putative DAT transmembrane domains could contribute to both aromatic and cationic interactions between DAT and dopamine or cocaine. We thus produced mutant DATs with alanine substitutions for tryptophans lying in or near putative DAT transmembrane domains. We have focused analyses on mutations that exert selective influences on affinities for dopamine or the cocaine analog CFT [(-)-2-beta-carbomethoxy-3-beta-(4-fluorophenyl)tropane]. Substitutions W162A, W255A, and W310A reduced dopamine uptake affinities. 5W266A, 12W555A, and 12W561A each reduced dopamine superficial recognition affinities by more than 3-fold and all retained affinity for CFT. W406A, W496A and W523A each reduced CFT affinity, and W84A increased CFT affinity. None of these four mutations decreased dopamine uptake affinity. These data, current provisional DAT structural models, and results from parallel studies of other mutants identify candidate dopamine-selective DAT domains for transmembrane dopamine permeation and regions in which mutations selectively lower CFT affinities. Tryptophan residues may contribute more extensively to these selective domains than other previously studied DAT amino acids. These sites provide tempting targets for selective blockers of cocaine recognition by DAT.

Alanine↗