Biomedical subjects

S Wu

Publications and source records attributed to S Wu.

At least 91 records · Page 5Linked to original sources

PubMed2001

The additive effect of neurotransmitter genes in pathological gambling.

As access to gambling increases there is a corresponding increase in the frequency of addiction to gambling, known as pathological gambling. Studies have shown that a number of different neurotransmitters are affected in pathological gamblers and that genetic factors play a role. Polymorphisms at 31 different genes involved in dopamine, serotonin, norepinephrine, GABA and neurotransmitters were genotyped in 139 pathological gamblers and 139 age, race, and sex-matched controls. Multivariate regression analysis was used with the presence or absence of pathological gambling as the dependent variable, and the 31 coded genes as the independent variables. Fifteen genes were included in the regression equation. The most significant were the DRD2, DRD4, DAT1, TPH, ADRA2C, NMDA1, and PS1 genes. The r(2) or fraction of the variance was less than 0.02 for most genes. Dopamine, serotonin, and norepinephrine genes contributed approximately equally to the risk for pathological gambling. These results indicate that genes influencing a range of brain functions play an additive role as risk factors for pathological gambling. Multi-gene profiles in specific individuals may be of assistance in choosing the appropriate treatment.

Adult↗

PubMed2001

Polymorphism of human HLA-DRB1 antigens generated by genetic exchange between DR2 (DRB115011) and DR6 (DRB11405) alleles: a novel DRB1 allele (DRB1*1437) identified in a Paiwan tribe member of Taiwan.

We report herein the identification of a new DRB1 allele using sequence-based typing (SBT). This novel allele, HLA-DRB1*1437, was found in an aboriginal individual from the Paiwan tribe in the southern part of Taiwan. This individual was typed by SBT method as having an HLA genotype of HLA-A*02011/0203, HLA-B*15011/3901, HLA-DRB1*11011/1437, HLA-DRB3*0202/0202, and HLA-DPB1*0501/1301. This new allele differs from DRB1*1309 in the 5'-end nucleotide sequence of polymorphic exon 2 at codon 16 (CAT-->CAA; H16Q), codon 37 (AAC-->TTC; R37F), codon 47 (TTC-->TAC; F47Y), and codon 58 (GCC-->GCT; both specify alanine). By sequence comparison, it was found that this new allele has a 5'-end sequence (from amino acid residues 7 to 66) identical to that found in the DRB1*1405 allele and a 3'-end sequence (from amino acid residues 58 to 94) identical to that found in the DRB1*15011 allele. Both DRB1*1405 and DRB1*15011 alleles have been identified among the Paiwan members (Note).

Alleles↗

PubMed2001

New DR5 sequences: a novel DRB111122 allele identified in Paiwan tribe members of Taiwan and a corrected sequence for the DRB11201 allele.

We report herein the identification of a new DRB1 allele using sequence-based typing (SBT). This novel allele, HLA-DRB1*11122, was found in an aboriginal individual (SWP71) from the Paiwan tribe in the southern part of Taiwan. This individual was typed by SBT method as having an HLA genotype of HLA-A*24021/24021, HLA-B*4001/4002, HLA-DRB1*11122/15011, HLA-DRB3*0202, and HLA-DRB5*01011. This new allele differs from DRB1*1112 in the polymorphic exon 2 only at codon 34 (CAA-->CAG; both specify glutamine) and from DRB1*1110 in the exon 2 sequence only at codon 32 (CAT-->TAT; H32T). The most likely candidate allele which is found in the aboriginal populations of Taiwan and which may mutate into this new allele is DRB1*11011. DRB1*11122 allele differs from DRB1*11011 allele in the polymorphic exon 2 at both codon 34 (CAA-->CAG) and codon 37 (TAC-->TTC; T37F). This novel HLA-DRB1*11122 allele was also found in another aboriginal individual (SWP90) from the same Paiwan tribe. This SWP90 individual was typed by SBT method as having an HLA genotype of HLA-A*24021/24021, HLA-B*4002/5502, HLA-DRB1*11122/1201, and HLA-DRB3*01011/0202. However, the original DRB1*1201 sequence from HERLUFF was found to be erroneously reported and the corrected sequence from SWP90 is now presented herein.

Alleles↗

PubMed2001

Cytokine-induced restoration of differentiation and cell cycle arrest in v-Myc transformed U-937 monoblasts correlates with reduced Myc activity.

Deregulated expression of the myc-family of oncogenes in hematopoietic and other cell types plays an important role in tumorigenesis, and results in increased proliferative potential and block of cellular differentiation. We have previously shown that IFN-gamma restores phorbol ester-induced differentiation and cell cycle arrest in v-myc transformed human U-937 monoblasts. To investigate whether other cytokine signals could also abrogate such a block, IL-1, IL-3, IL-4, IL-6, IL-7, IL-10, IL-11, LIF, oncostatin M, M-CSF, G-CSF and GM-CSF, and TGFbeta1, TNF-alpha, IFN-alpha were examined. We show that GM-CSF and IL-6, in combination with the phorbol ester 12-O-tetradecanoyl-phorbol acetate (TPA), restored differentiation and cell cycle arrest. In contrast, treatment by TGFbeta1 +/- TPA resulted in an efficient G1/G0 arrest, but did not appear to induce terminal differentiation. Restoration of differentiation and cell cycle arrest was accomplished despite maintained expression of the v-Myc protein. Our results show that the cytokine-induced signals reduced Myc-dependent transcription of an artificial target promoter/reporter gene construct, correlating in most, but not all, cases with decreased association of v- and c-Myc with its essential partner, Max. Thus, cytokine-induced signals may counteract the activity of deregulated Myc, and contribute to the normalization of differentiation, arrest in the G1/G0 phase of the cell cycle, or both.

Cell Cycle↗

PubMed2001

Selective determination of dopamine in the presence of ascorbic acid at an over-oxidized poly(N-acetylaniline) electrode.

An over-oxidized poly(N-acetylaniline) (PNAANI)/GCE was used to determine dopamine (DA) in a large excess of ascorbic acid (AA) by differential pulse voltammetry. A linear relation between Ip and DA concentration was found over the range 5.0 x 10(-7) to 2.0 x 10(-5) M. The detection limit was 1.68 x 10(-8) M for S/N = 3 and 400 microM AA did not interfere with the DA determination. The high sensitivity was due to accumulation and selectivity was due to charge discrimination. The mechanism of selective determination of DA at over-oxidized PNAANI/GCE was also proposed.

Ascorbic Acid↗

PubMed2001

Multivariate prognostic analysis of stage I(E) primary non-Hodgkin's lymphomas of the nasal cavity.

From January 1968 to December 1997, a total of 71 patients with stage I(E) (Ann Arbor staging system, 1971) primary non-Hodgkin's lymphomas of the nasal cavity received treatment in the Cancer Center of Sun Yat-Sen University of Medical Sciences. Thirty-seven lesions were limited to the nasal cavity (limited I(E)), whereas the other 34 were extended to the structure out of the nasal cavity (extended I(E)). Forty-four patients were treated with radiochemotherapy and 27 with radiotherapy alone. Kaplan-Meier methods were used in the survival analysis. Multivariate analysis was carried out using the Cox proportional hazard model. The 5- and 10-year survival rates were 71.85% and 59.67% for the patients with a complete response to irradiation, and both were 13.89% for the patients with residue lesions (p = 0.0004). The 5- and 10-year survival rates were 69.81% and 56.72% for limited I(E), and 40.65% and 35.57% for extended I(E) (p = 0.0047). The prognosis was better for those younger than 44 years (p = 0.0003). The 10-year survival rates for radiotherapy alone and combined radiochemotherapy are 52% and 75% for limited I(E) versus 37.58% and 45% for extended I(E) (p = 0.0644). B symptoms did not significantly affect clinical outcome (p = 0.729). Multivariate analysis showed that complete response of local lesion after radiotherapy, invasion of the primary tumor to adjacent structures, and patients' age were independent prognostic factors. Our study showed that radiotherapy is the main treatment method for the primary non-Hodgkin's lymphomas of the nasal cavity; the addition of chemotherapy may improve long-term survival. The local tumor response to radiotherapy, whether the extranasal structures were invaded, and patients' age were independent prognostic factors.

Adolescent↗

PubMed2001

Neither GABA(A) nor strychnine-sensitive glycine receptors are the sole mediators of MAC for isoflurane.

UNLABELLED: Inhaled anesthetics produce immobility (a cardinal aspect of general anesthesia) by an action on the spinal cord, possibly by potentiating the responses of gamma-amino-n-butyric acid (GABA(A)) and glycine receptors to GABA and glycine. In this study, we antagonized GABA(A) and glycine responses by intrathecal administration of picrotoxin (a noncompetitive GABA(A) antagonist), strychnine (a competitive glycine antagonist), or combinations of these drugs. We measured the capacity of antagonist infusion to increase isoflurane MAC (the minimum alveolar concentration of anesthetic that prevents movement in response to noxious stimuli in 50% of subjects). We found that these potent GABA(A) and glycine receptor antagonists had a ceiling effect, either alone or in combination increasing the MAC of isoflurane by at most 47%. IMPLICATIONS: gamma-amino-n-butyric acid and glycine receptors may in part be responsible for the immobilizing action of isoflurane. They are not, however, the only receptors that contribute to isoflurane-induced immobility (i.e., that determine the MAC of isoflurane).

Absorption↗

PubMed2001

Gene expression profiling in human fetal liver and identification of tissue- and developmental-stage-specific genes through compiled expression profiles and efficient cloning of full-length cDNAs.

Fetal liver intriguingly consists of hepatic parenchymal cells and hematopoietic stem/progenitor cells. Human fetal liver aged 22 wk of gestation (HFL22w) corresponds to the turning point between immigration and emigration of the hematopoietic system. To gain further molecular insight into its developmental and functional characteristics, HFL22w was studied by generating expressed sequence tags (ESTs) and by analyzing the compiled expression profiles of liver at different developmental stages. A total of 13,077 ESTs were sequenced from a 3'-directed cDNA library of HFL22w, and classified as follows: 5819 (44.5%) matched to known genes; 5460 (41.8%) exhibited no significant homology to known genes; and the remaining 1798 (13.7%) were genomic sequences of unknown function, mitochondrial genomic sequences, or repetitive sequences. Integration of ESTs of known human genes generated a profile including 1660 genes that could be divided into 15 gene categories according to their functions. Genes related to general housekeeping, ESTs associated with hematopoiesis, and liver-specific genes were highly expressed. Genes for signal transduction and those associated with diseases, abnormalities, or transcription regulation were also noticeably active. By comparing the expression profiles, we identified six gene groups that were associated with different developmental stages of human fetal liver, tumorigenesis, different physiological functions of Itoh cells against the other types of hepatic cells, and fetal hematopoiesis. The gene expression profile therefore reflected the unique functional characteristics of HFL22w remarkably. Meanwhile, 110 full-length cDNAs of novel genes were cloned and sequenced. These novel genes might contribute to our understanding of the unique functional characteristics of the human fetal liver at 22 wk.

Cloning, Molecular↗

PubMed2001

A novel method for beat-to-beat detection of ventricular late potentials.

A novel method for beat-to-beat detection of ventricular late potentials (VLP) from high-resolution electrocardiograms (ECGs) is presented. ECG signals from the X lead are first filtered using a bandpass filter, and then a time-sequence adaptive filter, to improve its signal-to-noise ratio. Eight features are extracted using wavelet transform, from the VLP time-frequency distribution of the filtered ECG signals, and used as inputs of specially designed artificial neural network for VLP recognition. The artificial neural network was trained and tested using clinical data, respectively. The results show that the presented method can detect beat-to-beat-based VLP with sensitivity of 80% and specificity of 77%, and the detection accuracy is 78%.

Action Potentials↗

PubMed2001

DNA from uncultured organisms as a source of 2,5-diketo-D-gluconic acid reductases.

Total DNA of a population of uncultured organisms was extracted from soil samples, and by using PCR methods, the genes encoding two different 2,5-diketo-D-gluconic acid reductases (DKGRs) were recovered. Degenerate PCR primers based on published sequence information gave internal gene fragments homologous to known DKGRs. Nested primers specific for the internal fragments were combined with random primers to amplify flanking gene fragments from the environmental DNA, and two hypothetical full-length genes were predicted from the combined sequences. Based on these predictions, specific primers were used to amplify the two complete genes in single PCRs. These genes were cloned and expressed in Escherichia coli. The purified gene products catalyzed the reduction of 2,5-diketo-D-gluconic acid to 2-keto-L-gulonic acid. Compared to previously described DKGRs isolated from Corynebacterium spp., these environmental reductases possessed some valuable properties. Both exhibited greater than 20-fold-higher kcat/Km values than those previously determined, primarily as a result of better binding of substrate. The Km values for the two new reductases were 57 and 67 microM, versus 2 and 13 mM for the Corynebacterium enzymes. Both environmental DKGRs accepted NADH as well as NADPH as a cosubstrate; other DKGRs and most related aldo-keto reductases use only NADPH. In addition, one of the new reductases was more thermostable than known DKGRs.

Amino Acid Sequence↗

PubMed2001

Transcription profiling-based identification of Staphylococcus aureus genes regulated by the agr and/or sarA loci.

The advent of transcription profiling technologies has provided researchers with an unprecedented ability to study biological processes. Accordingly, a custom-made Affymetrix GeneChip, constituting >86% of the Staphylococcus aureus genome, was used to identify open reading frames that are regulated by agr and/or SarA, the two best-studied regulators of the organism's virulence response. RNA extracted from wild-type cells and agr, sarA, and agr sarA mutant cells in the early-, mid-, and late-log and stationary phases of growth was analyzed. Open reading frames with transcription patterns expected of genes either up- or downregulated in an agr- and/or SarA-dependent manner were identified. Oligonucleotide microarray and Northern blot analyses confirmed that the transcription of several known virulence genes, including hla (alpha-toxin) and spa (protein A), is regulated by each effector and provided insights about the regulatory cascades involved in both alpha-hemolysin and protein A expression. Several putative virulence factors were also identified as regulated by agr and/or SarA. In addition, genes that are involved in several biological processes but which are difficult to reconcile as playing a direct role in the organism's pathogenesis also appeared to be regulated by each effector, suggesting that products of both the agr and the sarA locus are more-global transcription regulators than previously realized.

Bacterial Proteins↗

PubMed2001

Kappa- but not delta-opioid receptors mediate effects of ischemic preconditioning on both infarct and arrhythmia in rats.

Two series of experiments were performed in the isolated perfused rat heart to determine the role of kappa- and delta-opioid receptors (OR) in cardioprotection of ischemic preconditioning (IP). In the first series of experiments, it was found that IP with two cycles of 5-min regional ischemia followed by 5-min reperfusion each reduced infarct size induced by 30-min ischemia, and the ameliorating effect of IP on infarct was attenuated with blockade of either 5 x 10(-6) mol/l nor-binaltorphimine (nor-BNI), a selective kappa-OR antagonist, or 5 x 10(-6) mol/l naltrindole (NTD), a selective delta-OR antagonist. The second series showed that U50,488H, a selective kappa-OR agonist, or D-Ala(2)-D-leu(5)-enkephalin (DADLE), a selective delta-OR agonist, dose dependently reduced the infarct size induced by ischemia, which mimicked the effects of IP. The effect of 10(-5) mol/l U50,488H on infarct was significantly attenuated by blockade of protein kinase C (PKC) with specific PKC inhibitors, 5 x 10(-6) mol/l chelerythrine or 8 x 10(-7) mol/l calphostin C, as well as by blockade of ATP-sensitive K(+) (K(ATP)) channels with blockers of the channel, 10(-5) mol/l glibenclamide or 10(-4) mol/l 5-hydroxydecanoate. IP also reduced arrhythmia induced by ischemia. Nor-BNI, but not NTD, attenuated, while U50,488H, but not DADLE, mimicked the antiarrhythmic action of IP. In conclusion, the present study has provided first evidence that kappa-OR mediates the ameliorating effects of IP on infarct and arrhythmia induced by ischemia, whereas delta-OR mediates the effects only on infarct. Both PKC and K(ATP) channels mediate the effect of activation of kappa-OR on infarct.

3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cycloh↗

PubMed2001

Inducible HSP70 mediates delayed cardioprotection via U-50488H pretreatment in rat ventricular myocytes.

To test the hypothesis that heat-shock proteins (HSPs) mediate delayed cardioprotection of prior kappa-opioid receptor (kappa-OR) stimulation, we first correlated cellular injury and viability with the expression of HSP70s in isolated rat ventricular myocytes subjected to prior kappa-OR stimulation with the selective agonist trans-(+/-)-3,4-dichloro-N-methyl-N-[2-(1-pyrrolidinyl)cyclohexyl]benzeneacetamide (U-50488H) and delayed lethal simulated ischemia (LSI). Cell injury and viability were indicated by lactate dehydrogenase release and trypan blue exclusion, respectively. The reduced injury and increased viability after pretreatment with U-50488H were concentration dependent and correlated directly with the expression of both stress-inducible (HSP70) and constitutive (HSC70) proteins. The effects mimic those with metabolic inhibition preconditioning (MIP). The cardioprotection against LSI by pretreatment with U-50488H and MIP was abolished and antagonized, respectively, via blockade of the kappa-OR by its selective antagonist, nor-binaltorphimine. We also found that blockade of the production of HSP70 but not HSC70 blocked the inhibitory effect of pretreatment with U-50488H on injury and viability. These observations provide evidence that stress-inducible HSP70 mediates delayed cardioprotection of prior kappa-OR stimulation.

3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cycloh↗

PubMed2001

Longitudinal study of blood pressure and stroke in over 37,000 People in China.

As part of a longitudinal study performed in urban China, 37,655 subjects were evaluated for stroke risk factors, including having their blood pressure measured in a standard fashion. The cohort was followed for 3.5 years during which time 427 subjects experienced incident strokes--221 ischemic, 203 hemorrhagic, and 3 undefined. Both systolic and diastolic blood pressure were significantly related to risk of stroke and stroke type. Associations were stronger for systolic than diastolic blood pressure. These results emphasize the importance of systolic blood pressure, as opposed to diastolic, as a risk factor for stroke. In this study, the risk of stroke is increased by about 25% with each 10 mm Hg increase in systolic blood pressure.

Adult↗

PubMed2001

Population coding with correlation and an unfaithful model.

This study investigates a population decoding paradigm in which the maximum likelihood inference is based on an unfaithful decoding model (UMLI). This is usually the case for neural population decoding because the encoding process of the brain is not exactly known or because a simplified decoding model is preferred for saving computational cost. We consider an unfaithful decoding model that neglects the pair-wise correlation between neuronal activities and prove that UMLI is asymptotically efficient when the neuronal correlation is uniform or of limited range. The performance of UMLI is compared with that of the maximum likelihood inference based on the faithful model and that of the center-of-mass decoding method. It turns out that UMLI has advantages of decreasing the computational complexity remarkably and maintaining high-level decoding accuracy. Moreover, it can be implemented by a biologically feasible recurrent network (Pouget, Zhang, Deneve, & Latham, 1998). The effect of correlation on the decoding accuracy is also discussed.

Algorithms↗

PubMed2001

Attention modulation of neural tuning through peak and base rate.

This study investigates the influence of attention modulation on neural tuning functions. It has been shown in experiments that attention modulation alters neural tuning curves. Attention has been considered at least to serve to resolve limiting capacities and to increase the sensitivity to attended stimulus, while the exact functions of attention are still under debate. Inspired by recent experimental results on attention modulation, we investigate the influence of changes in the height and base rate of the tuning curve on the encoding accuracy, using the Fisher information. Under an assumption of stimulus-conditional independence of neural responses, we derive explicit conditions that determine when the height and base rate should be increased or decreased to improve encoding accuracy. Notably, a decrease in the tuning height and base rate can improve the encoding accuracy in some cases. Our theoretical results can predict the effective size of attention modulation on the neural population with respect to encoding accuracy. We discuss how our method can be used quantitatively to evaluate different aspects of attention function.

Animals↗

PubMed2001

Selenium decreases thyroglobulin concentrations but does not affect the increased thyroxine-to-triiodothyronine ratio in children with congenital hypothyroidism.

Compared with euthyroid controls, patients with congenital hypothyroidism (CH) who are receiving L-T(4) treatment show elevated serum TSH relative to serum T(4) concentrations and increased T(4)/T(3) ratio. These abnormalities could be the consequence of impaired activity of the selenoenzymes deiodinases on which patients with CH rely to convert the ingested L-T(4) into active T(3). Eighteen patients (0.5-15.4 yr), diagnosed with CH in infancy, received selenomethionine (SeM, 20-60 microg selenium/day) for 3 months. The study took place in Belgium, a country where selenium intake is borderline. Compared with the values observed in age- and sex-matched euthyroid controls, patients with CH had decreased selenium, thyroglobulin and T(3) concentrations and increased TSH, reverse T(3), and T(4) concentrations and T(4)/T(3) ratio at baseline. Selenium supplementation caused a 74% increase in plasma selenium values but did not affect the activity of the selenoenzyme glutathione peroxidase used as a marker of selenium status. SeM abolished the TSH difference observed between CH patients and euthyroid controls at baseline and caused a significant decrease in thyroglobulin values. Thyroid hormone concentrations were not affected by SeM. In conclusion, our data suggest that selenium is not a limiting factor for peripheral T(4)-to-T(3) conversion in CH patients. In contrast, we find indirect evidence that SeM improves thyroid hormones feedback at the hypothalamo-pituitary level and decreases stimulation of the residual thyroid tissue, possibly suggesting greater intracellular T(4)-to-T(3) conversion.

Adolescent↗

PubMed2001

Pulmonary fibrosis with intractable pneumothorax: new pulmonary manifestation of relapsing polychondritis.

Relapsing Polychondritis is a rare disease which causes the repetitive inflammation of cartilage and connective tissues. Although the large airway is sometimes involved and the stenosis of them often influences the prognosis of the patients, there have been few reports concerning the manifestation of the peripheral lung. A 60-year-old man with pulmonary fibrosis was admitted to a regional hospital due to sudden deafness, and then he suffered from relapsing polychondritis. During the steroid therapy, he also suffered from bilateral pneumothoraces. His computed tomogram revealed many bilateral bullae, emphysematous changes, and fibrotic changes in bilateral lungs. The mechanism of generating peripheral pulmonary manifestations is also discussed.

Blood Cell Count↗