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Agachan F, Chen T, Pfeifer J, Reissman P, Wexner SD. A constipation scoring system to simplify evaluation and management of constipated patients. Dis Colon Rectum 1996; 39:681-5. [PMID: 8646957 DOI: 10.1007/bf02056950] [Citation(s) in RCA: 823] [Impact Index Per Article: 28.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
PURPOSE Constipation is a common complaint; however, clinical presentation varies with each individual. The aim of this study was to assess a standard scoring system for evaluation of constipated patients. MATERIALS AND METHODS All consecutive patients with idiopathic constipation who were referred for anorectal physiologic testing were assessed. A subjective constipation score was calculated based on a detailed questionnaire that included over 100 constipation-related symptoms. Based on the questionnaire, scores ranged from 0 to 30, with 0 indicating normal and 30 indicating severe constipation. The constipation score was then compared with the objective findings of the physiology tests, which include colonic transit time (CTT), anal manometry (AM), cinedefecography (CD), and electromyography (EMG). Colonic inertia was defined as diffuse marker delay on CTT without evidence of paradoxical contraction on AM, CD, or EMG. Pelvic outlet obstruction was defined as paradoxical puborectalis contraction, rectal prolapse or rectoanal intussusception, rectocele, or sigmoidocele. RESULTS A total of 232 patients (185 females and 47 males) of a mean age of 64.9 (range, 14-92) years were evaluated. All patients had a score of more than 15; on evaluation of the significance of different symptoms in the constipation score with the Pearson's linear correlation test, 8 of 18 factors were identified as significant (P < 0.05). These factors included frequency of bowel movements, painful evacuation, incomplete evacuation, abdominal pain, length of time per attempt, assistance for evacuation, unsuccessful attempts for evacuation per 24 hours, and duration of constipation. All 232 patients had objective obstruction attributable to one or more of the following causes: paradoxical puborectalis contraction (81), significant rectocele or sigmoidocele (48), rectoanal intussusception (64), and rectal prolapse (9). CONCLUSION The proposed constipation scoring system correlated well with objective physiologic findings in constipated patients to allow uniformity in assessment of the severity of constipation.
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29 |
823 |
2
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Paweletz CP, Charboneau L, Bichsel VE, Simone NL, Chen T, Gillespie JW, Emmert-Buck MR, Roth MJ, Petricoin III EF, Liotta LA. Reverse phase protein microarrays which capture disease progression show activation of pro-survival pathways at the cancer invasion front. Oncogene 2001; 20:1981-9. [PMID: 11360182 DOI: 10.1038/sj.onc.1204265] [Citation(s) in RCA: 683] [Impact Index Per Article: 28.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2000] [Revised: 01/10/2001] [Accepted: 01/15/2001] [Indexed: 12/23/2022]
Abstract
Protein arrays are described for screening of molecular markers and pathway targets in patient matched human tissue during disease progression. In contrast to previous protein arrays that immobilize the probe, our reverse phase protein array immobilizes the whole repertoire of patient proteins that represent the state of individual tissue cell populations undergoing disease transitions. A high degree of sensitivity, precision and linearity was achieved, making it possible to quantify the phosphorylated status of signal proteins in human tissue cell subpopulations. Using this novel protein microarray we have longitudinally analysed the state of pro-survival checkpoint proteins at the microscopic transition stage from patient matched histologically normal prostate epithelium to prostate intraepithelial neoplasia (PIN) and then to invasive prostate cancer. Cancer progression was associated with increased phosphorylation of Akt (P<0.04), suppression of apoptosis pathways (P<0.03), as well as decreased phosphorylation of ERK (P<0.01). At the transition from histologically normal epithelium to PIN we observed a statistically significant surge in phosphorylated Akt (P<0.03) and a concomitant suppression of downstream apoptosis pathways which proceeds the transition into invasive carcinoma.
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Journal Article |
24 |
683 |
3
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Brent DA, Baugher M, Bridge J, Chen T, Chiappetta L. Age- and sex-related risk factors for adolescent suicide. J Am Acad Child Adolesc Psychiatry 1999; 38:1497-505. [PMID: 10596249 DOI: 10.1097/00004583-199912000-00010] [Citation(s) in RCA: 421] [Impact Index Per Article: 16.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
OBJECTIVE To examine the impact of age and sex on adolescent suicide risk. METHOD A standard psychological autopsy protocol was used to compare 140 suicide victims with 131 community controls. The risk factors for older (> or = 16 years) and younger, and for male and female suicide were compared. RESULTS Mood disorders, parental psychopathology, lifetime history of abuse, availability of a gun, and past suicide attempt conveyed significant risk for suicide across all 4 demographic groups. Psychopathology, particularly substance abuse (alone and comorbid with mood disorder), was more common and conveyed a much higher risk for suicide in the older versus younger adolescents. Younger suicide victims showed lower suicidal intent. Males chose more irreversible methods, and conduct disorder was both more prevalent and a more significant risk factor in males. CONCLUSIONS The increased rate of suicide in older versus younger adolescents is due in part to greater prevalence of psychopathology, namely substance abuse, and greater suicidal intent in the older population. The increased rate in males is less easily explained, but it may stem from method choice and the greater prevalence of and risk conveyed by conduct disorder in males.
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Comparative Study |
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421 |
4
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25 |
374 |
5
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Chen T, Barton SC, Binyamin G, Gao Z, Zhang Y, Kim HH, Heller A. A miniature biofuel cell. J Am Chem Soc 2001; 123:8630-1. [PMID: 11525685 DOI: 10.1021/ja0163164] [Citation(s) in RCA: 343] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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24 |
343 |
6
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Wyrick JJ, Aparicio JG, Chen T, Barnett JD, Jennings EG, Young RA, Bell SP, Aparicio OM. Genome-wide distribution of ORC and MCM proteins in S. cerevisiae: high-resolution mapping of replication origins. Science 2001; 294:2357-60. [PMID: 11743203 DOI: 10.1126/science.1066101] [Citation(s) in RCA: 307] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
DNA replication origins are fundamental to chromosome organization and duplication, but understanding of these elements is limited because only a small fraction of these sites have been identified in eukaryotic genomes. Origin Recognition Complex (ORC) and minichromosome maintenance (MCM) proteins form prereplicative complexes at origins of replication. Using these proteins as molecular landmarks for origins, we identified ORC- and MCM-bound sites throughout the yeast genome. Four hundred twenty-nine sites in the yeast genome were predicted to contain replication origins, and approximately 80% of the loci identified on chromosome X demonstrated origin function. A substantial fraction of the predicted origins are associated with repetitive DNA sequences, including subtelomeric elements (X and Y') and transposable element-associated sequences (long terminal repeats). These findings identify the global set of yeast replication origins and open avenues of investigation into the role(s) ORC and MCM proteins play in chromosomal architecture and dynamics.
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MESH Headings
- Binding Sites
- Cell Cycle Proteins/metabolism
- Chromosomes, Fungal/metabolism
- DNA Replication
- DNA Transposable Elements
- DNA, Fungal/biosynthesis
- DNA, Fungal/genetics
- DNA, Fungal/metabolism
- DNA, Intergenic
- DNA-Binding Proteins/metabolism
- Genome, Fungal
- Minichromosome Maintenance Complex Component 4
- Minichromosome Maintenance Complex Component 7
- Nuclear Proteins/metabolism
- Oligonucleotide Array Sequence Analysis
- Origin Recognition Complex
- RNA, Fungal/genetics
- RNA, Fungal/metabolism
- RNA, Transfer/genetics
- RNA, Transfer/metabolism
- Repetitive Sequences, Nucleic Acid
- Replication Origin
- Saccharomyces cerevisiae/genetics
- Saccharomyces cerevisiae/metabolism
- Saccharomyces cerevisiae Proteins/metabolism
- Telomere/metabolism
- Terminal Repeat Sequences
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24 |
307 |
7
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Yang XY, Wang LH, Chen T, Hodge DR, Resau JH, DaSilva L, Farrar WL. Activation of human T lymphocytes is inhibited by peroxisome proliferator-activated receptor gamma (PPARgamma) agonists. PPARgamma co-association with transcription factor NFAT. J Biol Chem 2000; 275:4541-4. [PMID: 10671476 DOI: 10.1074/jbc.275.7.4541] [Citation(s) in RCA: 305] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
T lymphocyte activation is highlighted by the induction of interleukin-2 (IL-2) gene expression, which governs much of the early lymphocyte proliferation responses. Peroxisome proliferator-activated receptor-gamma (PPARgamma) is a member of the nuclear receptor superfamily of ligand-activated transcription factors. PPARgamma mRNA expression was found in human peripheral blood T lymphocytes, raising the possibility of PPARgamma involvement in the regulation of T cell function. Here we show that PPARgamma ligands, troglitazone and 15-deoxy-Delta(12,14) prostaglandin J(2), but not PPARalpha agonist Wy14643, inhibited IL-2 production and phytohemagglutinin-inducible proliferation in human peripheral blood T-cells in a dose-dependent manner. This inhibitory effect on IL-2 was restricted to the PPARgamma2-expressing, not the PPARgamma-lacking, subpopulation of transfected Jurkat cells. The activated PPARgamma physically associates with transcriptional factor NFAT regulating the IL-2 promoter, blocking NFAT DNA binding and transcriptional activity. This interaction with T-cell-specific transcription factors indicates an important immunomodulatory role for PPARgamma in T lymphocytes and could suggest a previously unrecognized clinical potential for PPARgamma ligands as immunotherapeutic drugs to treat T-cell-mediated diseases by targeting IL-2 gene expression.
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305 |
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Budd Haeberlein S, Aisen PS, Barkhof F, Chalkias S, Chen T, Cohen S, Dent G, Hansson O, Harrison K, von Hehn C, Iwatsubo T, Mallinckrodt C, Mummery CJ, Muralidharan KK, Nestorov I, Nisenbaum L, Rajagovindan R, Skordos L, Tian Y, van Dyck CH, Vellas B, Wu S, Zhu Y, Sandrock A. Two Randomized Phase 3 Studies of Aducanumab in Early Alzheimer's Disease. J Prev Alzheimers Dis 2022; 9:197-210. [PMID: 35542991 DOI: 10.14283/jpad.2022.30] [Citation(s) in RCA: 305] [Impact Index Per Article: 101.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
BACKGROUND Alzheimer's disease is a progressive, irreversible, and fatal disease for which accumulation of amyloid beta is thought to play a key role in pathogenesis. Aducanumab is a human monoclonal antibody directed against aggregated soluble and insoluble forms of amyloid beta. OBJECTIVES We evaluated the efficacy and safety of aducanumab in early Alzheimer's disease. DESIGN EMERGE and ENGAGE were two randomized, double-blind, placebo-controlled, global, phase 3 studies of aducanumab in patients with early Alzheimer's disease. SETTING These studies involved 348 sites in 20 countries. PARTICIPANTS Participants included 1638 (EMERGE) and 1647 (ENGAGE) patients (aged 50-85 years, confirmed amyloid pathology) who met clinical criteria for mild cognitive impairment due to Alzheimer's disease or mild Alzheimer's disease dementia, of which 1812 (55.2%) completed the study. INTERVENTION Participants were randomly assigned 1:1:1 to receive aducanumab low dose (3 or 6 mg/kg target dose), high dose (10 mg/kg target dose), or placebo via IV infusion once every 4 weeks over 76 weeks. MEASUREMENTS The primary outcome measure was change from baseline to week 78 on the Clinical Dementia Rating Sum of Boxes (CDR-SB), an integrated scale that assesses both function and cognition. Other measures included safety assessments; secondary and tertiary clinical outcomes that assessed cognition, function, and behavior; and biomarker endpoints. RESULTS EMERGE and ENGAGE were halted based on futility analysis of data pooled from the first approximately 50% of enrolled patients; subsequent efficacy analyses included data from a larger data set collected up to futility declaration and followed prespecified statistical analyses. The primary endpoint was met in EMERGE (difference of -0.39 for high-dose aducanumab vs placebo [95% CI, -0.69 to -0.09; P=.012; 22% decrease]) but not in ENGAGE (difference of 0.03, [95% CI, -0.26 to 0.33; P=.833; 2% increase]). Results of biomarker substudies confirmed target engagement and dose-dependent reduction in markers of Alzheimer's disease pathophysiology. The most common adverse event was amyloid-related imaging abnormalities-edema. CONCLUSIONS Data from EMERGE demonstrated a statistically significant change across all four primary and secondary clinical endpoints. ENGAGE did not meet its primary or secondary endpoints. A dose- and time-dependent reduction in pathophysiological markers of Alzheimer's disease was observed in both trials.
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Clinical Trial, Phase III |
3 |
305 |
9
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Rodriguez DA, Weinlich R, Brown S, Guy C, Fitzgerald P, Dillon CP, Oberst A, Quarato G, Low J, Cripps JG, Chen T, Green DR. Characterization of RIPK3-mediated phosphorylation of the activation loop of MLKL during necroptosis. Cell Death Differ 2015; 23:76-88. [PMID: 26024392 DOI: 10.1038/cdd.2015.70] [Citation(s) in RCA: 293] [Impact Index Per Article: 29.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2015] [Revised: 04/28/2015] [Accepted: 04/28/2015] [Indexed: 12/14/2022] Open
Abstract
Mixed lineage kinase domain-like pseudokinase (MLKL) mediates necroptosis by translocating to the plasma membrane and inducing its rupture. The activation of MLKL occurs in a multimolecular complex (the 'necrosome'), which is comprised of MLKL, receptor-interacting serine/threonine kinase (RIPK)-3 (RIPK3) and, in some cases, RIPK1. Within this complex, RIPK3 phosphorylates the activation loop of MLKL, promoting conformational changes and allowing the formation of MLKL oligomers, which migrate to the plasma membrane. Previous studies suggested that RIPK3 could phosphorylate the murine MLKL activation loop at Ser345, Ser347 and Thr349. Moreover, substitution of the Ser345 for an aspartic acid creates a constitutively active MLKL, independent of RIPK3 function. Here we examine the role of each of these residues and found that the phosphorylation of Ser345 is critical for RIPK3-mediated necroptosis, Ser347 has a minor accessory role and Thr349 seems to be irrelevant. We generated a specific monoclonal antibody to detect phospho-Ser345 in murine cells. Using this antibody, a series of MLKL mutants and a novel RIPK3 inhibitor, we demonstrate that the phosphorylation of Ser345 is not required for the interaction between RIPK3 and MLKL in the necrosome, but is essential for MLKL translocation, accumulation in the plasma membrane, and consequent necroptosis.
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Research Support, Non-U.S. Gov't |
10 |
293 |
10
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Chen TY, Peng YW, Dhallan RS, Ahamed B, Reed RR, Yau KW. A new subunit of the cyclic nucleotide-gated cation channel in retinal rods. Nature 1993; 362:764-7. [PMID: 7682292 DOI: 10.1038/362764a0] [Citation(s) in RCA: 289] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Retinal rods respond to light with a membrane hyperpolarization produced by a G-protein-mediated signalling cascade that leads to cyclic GMP hydrolysis and the consequent closure of a cGMP-gated channel that is open in darkness. A protein that forms this channel has recently been purified from bovine retina and molecularly cloned, suggesting that the native cGMP-gated channel might be a homo-oligomer. Here we report the cloning of another protein from human retina which has only about 30% overall identity to the rod channel subunit. This protein, immunocytochemically localized to rod outer segments, does not form functional channels by itself. However, when co-expressed with the cloned human rod channel protein, it introduces rapid flickers to the channel openings that are characteristic of the native channel. The hetero-oligomeric channel is also highly sensitive to the blocker L-cis-diltiazem, like the native channel. This new protein thus seems to be another subunit of the native rod channel. The hetero-oligomeric nature of the rod channel means that it is no exception to a common motif shared by other ligand-gated channels.
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289 |
11
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Nassif N, Cense B, Park B, Pierce M, Yun S, Bouma B, Tearney G, Chen T, de Boer J. In vivo high-resolution video-rate spectral-domain optical coherence tomography of the human retina and optic nerve. OPTICS EXPRESS 2004; 12:367-76. [PMID: 19474832 DOI: 10.1364/opex.12.000367] [Citation(s) in RCA: 277] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
An ultra-high-speed spectral-domain optical coherence tomography system (SD-OCT) was developed for imaging the human retina and optic nerve in vivo at a sustained depth profile (A-line) acquisition speed of 29 kHz. The axial resolution was 6 microm in tissue and the system had shot-noise-limited performance with a maximum sensitivity of 98.4 dB. 3-dimensional data sets were collected in 11 and 13 seconds for the macula and optic nerve head respectively and are presented to demonstrate the potential clinical applications of SD-OCT in ophthalmology. Additionally, a 3-D volume of the optic nerve head was constructed from the acquired data and the retinal vascular network was visualized.
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277 |
12
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Chute JP, Chen T, Feigal E, Simon R, Johnson BE. Twenty years of phase III trials for patients with extensive-stage small-cell lung cancer: perceptible progress. J Clin Oncol 1999; 17:1794-801. [PMID: 10561217 DOI: 10.1200/jco.1999.17.6.1794] [Citation(s) in RCA: 275] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
PURPOSE All cooperative group studies performed in North America for patients with extensive-stage small-cell lung cancer (SCLC) were evaluated to determine the pattern of the clinical trials and the outcome of patients over the past 20 years. PATIENTS AND METHODS Phase III trials for patients with extensive-stage SCLC were identified through a search of the National Cancer Institute Cancer Therapy Evaluation Program database from 1972 to 1993. Patients with extensive-stage SCLC treated during a similar time interval listed in the Surveillance, Epidemiology, and End Results (SEER) database were also examined. Trends were tested in the number of trials over time, the number and sex of patients entered onto the trials, and the survival time of patients treated over time. RESULTS Twenty-one phase III trials for patients with extensive-stage SCLC were initiated between 1972 and 1990. The median of the median survival times of patients treated on the control arms of the phase III trials initiated between 1972 and 1981 was 7.0 months; for those patients enrolled onto control arms between 1982 and 1990, the median survival time was 8.9 months (P =.001). Analysis of the SEER database of patients with extensive-stage SCLC over the same time period shows a similar 2-month prolongation in median survival time. CONCLUSION Analysis of 21 phase III trials initiated in North America and the SEER database from 1972 to 1994 demonstrates that there has been a modest improvement in the survival time of patients with extensive-stage SCLC.
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Meta-Analysis |
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275 |
13
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Chen TY, Yau KW. Direct modulation by Ca(2+)-calmodulin of cyclic nucleotide-activated channel of rat olfactory receptor neurons. Nature 1994; 368:545-8. [PMID: 7511217 DOI: 10.1038/368545a0] [Citation(s) in RCA: 262] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Olfactory receptor neurons depolarize in response to odorant stimulation of their sensory cilia. One transduction mechanism involves a G-protein-mediated increase in adenylate cyclase activity, raising the internal cyclic AMP concentration to open a cyclic nucleotide-activated cation channel on the plasma membrane. An influx of Ca2+ through this channel, which is permeable to both monovalent and divalent cations, triggers olfactory adaptation. Previous work has indicated that at least part of this Ca(2+)-mediated adaptation resides in the channel itself, but the mechanism remains unclear and controversial. Here we use the cloned channel from rat expressed in a cell line and the native channel from rat olfactory receptor cells to show that Ca2+ reduces the apparent affinity of the channel for cAMP by up to 20-fold in the presence of calmodulin, an abundant protein in olfactory cilia. This decrease in apparent affinity appears to involve a direct interaction between Ca(2+)-calmodulin and the channel, and it can reduce the activation of the channel by cAMP by up to a few hundred-fold, suggesting that it may be a key component of the Ca(2+)-triggered olfactory adaptation.
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262 |
14
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Abstract
In this paper, we discuss delayed Hopfield neural networks, investigating their global exponential stability. Sufficient conditions ensuring global exponential stability of delayed Hopfield neural networks are given.
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259 |
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Liu M, Chen TY, Ahamed B, Li J, Yau KW. Calcium-calmodulin modulation of the olfactory cyclic nucleotide-gated cation channel. Science 1994; 266:1348-54. [PMID: 7526466 DOI: 10.1126/science.266.5189.1348] [Citation(s) in RCA: 256] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Although several ion channels have been reported to be directly modulated by calcium-calmodulin, they have not been conclusively shown to bind calmodulin, nor are the modulatory mechanisms understood. Study of the olfactory cyclic nucleotide-activated cation channel, which is modulated by calcium-calmodulin, indicates that calcium-calmodulin directly binds to a specific domain on the amino terminus of the channel. This binding reduces the effective affinity of the channel for cyclic nucleotides, apparently by acting on channel gating, which is tightly coupled to ligand binding. The data reveal a control mechanism that resembles those underlying the regulation of enzymes by calmodulin. The results also point to the amino-terminal part of the olfactory channel as an element for gating, which may have general significance in the operation of ion channels with similar overall structures.
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256 |
16
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Chen T, Chen H. Approximation capability to functions of several variables, nonlinear functionals, and operators by radial basis function neural networks. ACTA ACUST UNITED AC 2012; 6:904-10. [PMID: 18263378 DOI: 10.1109/72.392252] [Citation(s) in RCA: 252] [Impact Index Per Article: 19.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The purpose of this paper is to explore the representation capability of radial basis function (RBF) neural networks. The main results are: 1) the necessary and sufficient condition for a function of one variable to be qualified as an activation function in RBF network is that the function is not an even polynomial, and 2) the capability of approximation to nonlinear functionals and operators by RBF networks is revealed, using sample data either in frequency domain or in time domain, which can be used in system identification by neural networks.
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Journal Article |
13 |
252 |
17
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Yellen G, Sodickson D, Chen TY, Jurman ME. An engineered cysteine in the external mouth of a K+ channel allows inactivation to be modulated by metal binding. Biophys J 1994; 66:1068-75. [PMID: 8038379 PMCID: PMC1275814 DOI: 10.1016/s0006-3495(94)80888-4] [Citation(s) in RCA: 246] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Substitution of a cysteine in the extracellular mouth of the pore of the Shaker-delta K+ channel permits allosteric inhibition of the channel by Zn2+ or Cd2+ ions at micromolar concentrations. Cd2+ binds weakly to the open state but drives the channel into the slow (C-type) inactivated state, which has a Kd for Cd2+ of approximately 0.2 microM. There is a 45,000-fold increase in affinity when the channel changes from open to inactivated. These results indicate that C-type inactivation involves a structural change in the external mouth of the pore. This structural change is reflected in the T449C mutant as state-dependent metal affinity, which may result either from a change in proximity of the introduced cysteine residues of the four subunits or from a change of the exposure of this residue on the surface of the protein.
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research-article |
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246 |
18
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Hsu SY, Kudo M, Chen T, Nakabayashi K, Bhalla A, van der Spek PJ, van Duin M, Hsueh AJ. The three subfamilies of leucine-rich repeat-containing G protein-coupled receptors (LGR): identification of LGR6 and LGR7 and the signaling mechanism for LGR7. Mol Endocrinol 2000; 14:1257-71. [PMID: 10935549 DOI: 10.1210/mend.14.8.0510] [Citation(s) in RCA: 234] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Glycoprotein hormone receptors, including LH receptor, FSH receptor, and TSH receptor, belong to the large G protein-coupled receptor (GPCR) superfamily but are unique in having a large ectodomain important for ligand binding. In addition to two recently isolated mammalian LGRs (leucine-rich repeat-containing, G protein-coupled receptors), LGR4 and LGR5, we further identified two new paralogs, LGR6 and LGR7, for glycoprotein hormone receptors. Phylogenetic analysis showed that there are three LGR subgroups: the known glycoprotein hormone receptors; LGR4 to 6; and a third subgroup represented by LGR7. LGR6 has a subgroup-specific hinge region after leucine-rich repeats whereas LGR7, like snail LGR, contains a low density lipoprotein (LDL) receptor cysteine-rich motif at the N terminus. Similar to LGR4 and LGR5, LGR6 and LGR7 mRNAs are expressed in multiple tissues. Although the putative ligands for LGR6 and LGR7 are unknown, studies on single amino acid mutants of LGR7, with a design based on known LH and TSH receptor gain-of-function mutations, indicated that the action of LGR7 is likely mediated by the protein kinase A but not the phospholipase C pathway. Thus, mutagenesis of conserved residues to allow constitutive receptor activation is a novel approach for the characterization of signaling pathways of selective orphan GPCRs. The present study also defines the existence of three subclasses of leucine-rich repeat-containing, G protein-coupled receptors in the human genome and allows future studies on the physiological importance of this expanding subgroup of GPCR.
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MESH Headings
- Amino Acid Sequence
- Animals
- Chromosomes, Human, Pair 1
- Chromosomes, Human, Pair 4
- Cloning, Molecular
- Cyclic AMP-Dependent Protein Kinases/metabolism
- GTP-Binding Proteins/metabolism
- Gene Expression Regulation
- Humans
- Mammals
- Membrane Proteins
- Molecular Sequence Data
- Multigene Family
- Mutagenesis, Site-Directed
- Phylogeny
- Receptors, Cell Surface/genetics
- Receptors, Cell Surface/metabolism
- Receptors, G-Protein-Coupled
- Receptors, LH/genetics
- Receptors, LH/metabolism
- Receptors, Peptide
- Recombinant Proteins/genetics
- Recombinant Proteins/metabolism
- Repetitive Sequences, Amino Acid
- Sequence Homology, Amino Acid
- Signal Transduction
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234 |
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Krishnan K, Chen T, Paster BJ. A practical guide to the oral microbiome and its relation to health and disease. Oral Dis 2016; 23:276-286. [PMID: 27219464 DOI: 10.1111/odi.12509] [Citation(s) in RCA: 223] [Impact Index Per Article: 24.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2016] [Accepted: 05/18/2016] [Indexed: 12/14/2022]
Abstract
The oral microbiome is incredibly complex with the average adult harboring about 50-100 billion bacteria in the oral cavity, which represent about 200 predominant bacterial species. Collectively, there are approximately 700 predominant taxa of which less than one-third still have not yet been grown in vitro. Compared to other body sites, the oral microbiome is unique and readily accessible. There is extensive literature available describing the oral microbiome and discussing the roles that bacteria may play in oral health and disease. However, the purpose of this review is not to rehash these detailed studies but rather to educate the reader with understanding the essence of the oral microbiome, namely that there are abundant bacteria in numbers and types, that there are molecular methods to rapidly determine bacterial associations, that there is site specificity for colonization of the host, that there are specific associations with oral health and disease, that oral bacteria may serve as biomarkers for non-oral diseases, and that oral microbial profiles may have potential use to assess disease risk.
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Review |
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223 |
20
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Fratacci MD, Frostell CG, Chen TY, Wain JC, Robinson DR, Zapol WM. Inhaled nitric oxide. A selective pulmonary vasodilator of heparin-protamine vasoconstriction in sheep. Anesthesiology 1991; 75:990-9. [PMID: 1741521 DOI: 10.1097/00000542-199112000-00011] [Citation(s) in RCA: 220] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Nitric oxide (NO) has recently been discovered to be an important endothelium-derived relaxing factor and produces profound relaxation of vascular smooth muscle. To learn if NO could be a potent and selective pulmonary vasodilator, NO was inhaled by 16 awake lambs in an attempt to reduce the increase in pulmonary artery pressure (PAP) and pulmonary vascular resistance (PVR) induced by either the infusion of an exogenous pulmonary vasoconstrictor (the thromboxane analog U46619) or the endogenous release of thromboxane that occurs during the neutralization of heparin anticoagulation by protamine sulfate. Inhaling greater than or equal to 40 ppm of NO during a continuous U46619 infusion returned the PAP to a normal value, without affecting systemic blood pressure or vascular resistance. Pretreatment with the cyclooxygenase inhibitor indomethacin before infusing U46619 did not reduce the pulmonary vasodilatory effect of inhaled NO, and we conclude that the dilatory effect of NO on the lung's circulation is independent of cyclooxygenase products such as prostacyclin. Continuously inhaling NO at 180 ppm did not significantly reduce the mean peak thromboxane B2 concentration at 1 min after protamine injection; however, the mean values of pulmonary hypertension and vasoconstriction at 1 min were markedly reduced below the levels in untreated heparin-protamine reactions. Breathing NO at lower concentrations (40-80 ppm) did not decrease the mean peak PAP and PVR at 1 min after protamine but decreased the PAP and PVR values at 2, 3, and 5 min below those of control heparin-protamine reactions. Intravenous infusion of nitroprusside completely prevented the transient increase of PAP and PVR during the heparin-protamine reaction; however, marked concomitant systemic vasodilation occurred. Inhaled NO is a selective pulmonary vasodilator that can prevent thromboxane-induced pulmonary hypertension during the heparin-protamine reaction in lambs and can do so without causing systemic vasodilation.
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Moore L, Chen T, Knapp HR, Landon EJ. Energy-dependent calcium sequestration activity in rat liver microsomes. J Biol Chem 1975. [DOI: 10.1016/s0021-9258(19)41338-0] [Citation(s) in RCA: 211] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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Klebe RJ, Chen T, Ruddle FH. Controlled production of proliferating somatic cell hybrids. J Biophys Biochem Cytol 1970; 45:74-82. [PMID: 4318843 PMCID: PMC2107999 DOI: 10.1083/jcb.45.1.74] [Citation(s) in RCA: 209] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
The techniques described permit the controlled production of large numbers of proliferating somatic cell hybrids in a relatively short period of time. Sendai virus is used to promote cell hybridization. beta-propriolactone is employed as the inactivating agent of Sendai virus since it produces complete loss of viral infectivity while preserving viral fusion capacity. Cells are fused in monolayer, instead of in suspension, since fixing cells in two dimensions permits one to control cell contacts during the fusion event through the expedient of varying multiplicities of the parental cells and the total cell density. Under the conditions described, a several hundred fold increase in the number of hybrid clones obtained is seen as compared to the controls.
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Abstract
The gating of ClC-0, the voltage-dependent Cl- channel from Torpedo electric organ, is strongly influenced by Cl- ions in the external solution. Raising external Cl- over the range 1-600 mM favors the fast-gating open state and disfavors the slow-gating inactivated state. Analysis of purified single ClC-0 channels reconstituted into planar lipid bilayers was used to identify the role of Cl- ions in the channel's fast voltage-dependent gating process. External, but not internal, Cl- had a major effect on the channel's opening rate constant. The closing rate was more sensitive to internal Cl- than to external Cl-. Both opening and closing rates varied with voltage. A model was derived that postulates (a) that in the channel's closed state, Cl- is accessible to a site located at the outer end of the conduction pore, where it binds in a voltage-independent fashion, (b) that this closed conformation can open, whether liganded by Cl- or not, in a weakly voltage-dependent fashion, (c) that the Cl(-)-liganded closed channel undergoes a conformational change to a different closed state, such that concomitant with this change, Cl- ion moves inward, conferring voltage-dependence to this step, and (d) that this new Cl(-)-liganded closed state opens with a very high rate. According to this picture, Cl- movement within the pre-open channel is the major source of voltage dependence, and charge movement intrinsic to the channel protein contributes very little to voltage-dependent gating of ClC-0. Moreover, since the Cl- activation site is probably located in the ion conduction pathway, the fast gating of ClC-0 is necessarily coupled to ion conduction, a nonequilibrium process.
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Thies RS, Chen T, Davies MV, Tomkinson KN, Pearson AA, Shakey QA, Wolfman NM. GDF-8 propeptide binds to GDF-8 and antagonizes biological activity by inhibiting GDF-8 receptor binding. Growth Factors 2001; 18:251-9. [PMID: 11519824 DOI: 10.3109/08977190109029114] [Citation(s) in RCA: 199] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
GDF-8 is a new member of the TGF-beta superfamily which appears to be a negative regulator of skeletal muscle mass. Factors which regulate the biological activity of GDF-8 have not yet been identified. However, the biological activities of TGF-beta superfamily members, TGF-beta1, -beta2 and -beta3, can be inhibited by noncovalent association with TGF-beta1, -beta2 and beta3 propeptides cleaved from the amino-termini of the TGF-beta precursor proteins. In contrast, the propeptides of other TGF-beta superfamily members do not appear to be inhibitory. In this investigation, we demonstrate that purified recombinant GDF-8 propeptide associates with purified recombinant GDF-8 to form a noncovalent complex, as evidenced by size exclusion chromatography and chemical crosslinking analysis. Furthermore, we show that GDF-8 propeptide inhibits the biological activity of GDF-8 assayed on A204 rhabdomyosarcoma cells transfected with a (CAGA)12 reporter construct. Finally, we demonstrate that GDF-8 propeptide inhibits specific GDF-8 binding to L6 myoblast cells. Collectively, these data identify the GDF-8 propeptide as an inhibitor of GDF-8 biological activity.
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Yang J, Chen T, Sun L, Zhao Z, Qi X, Zhou K, Cao Y, Wang X, Qiu Y, Su M, Zhao A, Wang P, Yang P, Wu J, Feng G, He L, Jia W, Wan C. Potential metabolite markers of schizophrenia. Mol Psychiatry 2013; 18:67-78. [PMID: 22024767 PMCID: PMC3526727 DOI: 10.1038/mp.2011.131] [Citation(s) in RCA: 193] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Schizophrenia is a severe mental disorder that affects 0.5-1% of the population worldwide. Current diagnostic methods are based on psychiatric interviews, which are subjective in nature. The lack of disease biomarkers to support objective laboratory tests has been a long-standing bottleneck in the clinical diagnosis and evaluation of schizophrenia. Here we report a global metabolic profiling study involving 112 schizophrenic patients and 110 healthy subjects, who were divided into a training set and a test set, designed to identify metabolite markers. A panel of serum markers consisting of glycerate, eicosenoic acid, β-hydroxybutyrate, pyruvate and cystine was identified as an effective diagnostic tool, achieving an area under the receiver operating characteristic curve (AUC) of 0.945 in the training samples (62 patients and 62 controls) and 0.895 in the test samples (50 patients and 48 controls). Furthermore, a composite panel by the addition of urine β-hydroxybutyrate to the serum panel achieved a more satisfactory accuracy, which reached an AUC of 1 in both the training set and the test set. Multiple fatty acids and ketone bodies were found significantly (P<0.01) elevated in both the serum and urine of patients, suggesting an upregulated fatty acid catabolism, presumably resulting from an insufficiency of glucose supply in the brains of schizophrenia patients.
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