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T Chiang

Publications and source records attributed to T Chiang.

At least 19 recordsLinked to original sources
PubMed2002

Evaluation on the use of a portable unit versus the laboratory for the monitoring of International Normalized Ratio (INR) in orally anticoagulated patients.

INTRODUCTION: Measuring the International Normalized Ratio (INR) through a laboratory requires venipuncture and takes about 1 hour for results to be available. A portable monitor (CoaguChek Plus System), which measures the INR using fingerstick samples, is evaluated in this study to determine its clinical significance in anticoagulated and non-anticoagulated individuals. The hospital's outpatient and inpatient laboratories were also compared in the study. MATERIALS AND METHODS: Paired venous and capillary blood INRs were performed on anticoagulated patients using the monitor and the Singapore General Hospital (SGH) outpatient and inpatient laboratories (OPS and IPS labs). Paired INRs of control samples were also performed using the monitor and the IPS lab. RESULTS: We plotted the difference in INR by the 2 methods (monitor and OPS lab, n = 91) against their mean, and calculated the limits of agreement (95% of the difference would lie between -0.90 to 0.70). After a logarithmic transformation on the data, we found that for 95% of the cases, the OPS lab would differ from the monitor by 13% below to 14% above. There was also a marginal difference (95% limits of agreement of -0.14 to 0.10) when we compared the INR obtained from OPS and IPS laboratories (n = 43). Our control sample (n = 19) showed that the 95% confidence interval for the bias was -0.04 to 0.10. CONCLUSION: The monitor should be used with caution in patients with INR > 3. We suggest use of the monitor in situations where the non-anticoagulated state of a patient needs to be measured. There is a difference in INR measured by laboratories within the same institution.

Anticoagulants↗
PubMed2001

Identification and characterization of a novel androgen receptor coregulator ARA267-alpha in prostate cancer cells.

The androgen receptor (AR) is a member of the steroid receptor superfamily that binds to the androgen response element to regulate target gene transcription. AR may need to interact with some selected coregulators for maximal or proper androgen function. Here we report the isolation of a new AR coregulator with a calculated molecular mass of 267 kDa named the androgen receptor-associated protein 267-alpha (ARA267-alpha). ARA267-alpha contains 2427 amino acids, including one Su(var)3-9, Enhancer-of-zeste, and Trithorax (SET) domain, two LXXLL motifs, three nuclear translocation signal (NLS) sequences, and four plant homeodomain (PHD) finger domains. Northern blot analyses reveal that ARA267-alpha is expressed predominantly in the lymph node as 13- and 10-kilobase transcripts. HepG2 is the only cell line tested that does not express ARA267-alpha. Yeast two-hybrid and glutathione S-transferase pull-down assays show that both the N and C terminus of ARA267-alpha interact with the AR DNA- and ligand-binding domains. Unlike other coregulators, such as CBP, which enhance the interaction between the N and C terminus of AR, we found that ARA267-alpha had little influence on the interaction between the N and C terminus of AR. Luciferase and chloramphenicol acetyltransferase assays show that ARA267-alpha can enhance AR transactivation in a dihydrotestosterone-dependent manner in PC-3 and H1299 cells. ARA267-alpha can also enhance AR transactivation with other coregulators, such as ARA24 or PCAF, a histone acetylase, in an additive manner. Together, our data demonstrate that ARA267-alpha is a new AR coregulator containing the SET domain with an exceptionally large molecular mass that can enhance AR transactivation in prostate cancer cells.

Amino Acid Sequence↗
PubMed2001

Promoter CpG methylation of Hox-a10 and Hox-a11 in mouse uterus not altered upon neonatal diethylstilbestrol exposure.

Mouse abdominal B-like Hoxa genes are expressed and functionally required in the developing reproductive tracts. Mice lacking either Hoxa-10 or Hoxa-11, two of the AbdB Hoxa genes, exhibit abnormal uterine development similar to that induced by in utero diethylstilbestrol (DES) exposure. Indeed, uterine Hoxa-10 and Hoxa-11 expression is potently repressed by perinatal DES exposure, providing a potential molecular mechanism for DES-induced reproductive tract malformations. We have shown previously that DES can permanently alter uterine lactoferrin gene expression through modulation of the lactoferrin promoter methylation pattern. Here we ask whether a similar mechanism also functions to deregulate uterine Hoxa-10 or Hoxa-11 expression during neonatal DES exposure. We mapped the Hoxa-10 promoter by cloning a 1.485 kb DNA fragment 5' of the Hoxa-10 exon1a. A 5' rapid amplification of cDNA ends (RACE) experiment revealed a transcription start site for the a10-1 transcript. Functional analysis of the proximal 200-bp sequences demonstrated significant promoter activity, confirming the location of the Hoxa-10 promoter. Moreover, methylation assays performed on eight CpGs in Hoxa-10 and 19 CpGs in Hoxa-11 proximal promoters demonstrated that all these CpGs were highly unmethylated in both control and DES-dosed mice from postnatal day 5 to day 30. Significant methylation around Hoxa-10 and Hoxa-11 promoters was only observed in DES-induced uterine carcinomas in 18-mo-old mice. Our results suggest that DES-induced downregulations of Hoxa-10 or Hoxa-11 gene expression are not associated with methylation changes in their proximal promoters and that gene imprinting by developmental DES exposure may be a gene-specific phenomenon.

Animals↗
PubMed2001

Transthoracic and transesophageal echocardiographic diagnosis of aneurysm of the sinus of Valsalva: a review of five year experience.

BACKGROUND: Aneurysms of the sinus of Valsalva (SVA) are uncommon congenital lesions. The clinical presentations vary from asymptomatic to progressive heart failure following rupture of the aneurysm into an adjacent cardiac chamber. Retrograde aortogram is the diagnostic tool of choice preoperatively. Recent studies have demonstrated that the SVA can be accurately diagnosed using transthoracic two-dimensional, and color Doppler flow mapping, even for surgical preparation without cardiac catheterization. We report our 5-year experience of transthoracic echocardiography (TTE) and transesophageal echocardiography (TEE) in the evaluation of SVA. METHODS: Eleven adult patients with SVA with or without rupture were studied using both TTE and TEE. All of the diagnoses were subsequently comfirmed by either cardiac catheterization or surgical findings. RESULTS: Aneurysms originated in the right coronary sinus (n = 9) and noncoronary sinus (n = 2); they ruptured into the right ventricle in 5 patients and the right atrium in 5 patients. An unruptured right SVA was noted in 1 patient. Both TTE and TEE could identify the site of the aneurysm, rupture sites, and the receiving chamber equally well. Co-existent cardiac lesions included 11 cases of valvular aortic regurgitation (mild in 7, moderate in 2 and severe in 2). Two cases of perimembranous type ventricular septal defect (VSD) and 6 cases of supracristal type VSD (including 1 case of tetraology of Fallot, 3 supracristal, 1 muscular and 1 subaortic) were noted. Three cases were complicated with valvular vegetations (1 aortic valve, 1 aortic and tricuspid valve and 1 aortic and pulmonic valve). One patient had patent ductus arteriosus and 2 patients had pulmonic valvular stenosis. CONCLUSIONS: TEE provides clearer definition for the detailed anatomy of the ruptured sac and co-existent cardiac lesions than TTE through high resolution and closer approach. We conclude that TEE is a powerful complementary diagnostic tool in the evaluation of patients with SVA. TEE also provides additionally useful information for guiding the surgical approach and for assessing the operative results even without cardiac catheterization.

Adult↗
PubMed2000

Sn/Ge(111) surface charge-density-wave phase transition

Angle-resolved photoemission has been utilized to study the surface electronic structure of 1 / 3 monolayer of Sn on Ge(111) in both the room-temperature (sqrt[3]xsqrt[3] )R30 degrees phase and the low-temperature ( 3x3) charge-density-wave phase. The results reveal a gap opening around the ( 3x3) Brillouin zone boundary, suggesting a Peierls-like transition despite the well-documented lack of Fermi nesting. A highly sensitive electronic response to doping by intrinsic surface defects is the cause for this unusual behavior, and a detailed calculation illustrates the origin of the ( 3x3) symmetry.

Journal Article↗
PubMed2000

d-band quantum well states

Observations of d-band quantum well states are made for atomically uniform Ag films on Fe(100) using angle-resolved photoemission. For increasing film thicknesses, quantum well peaks within the small 4d bandwidth multiply rapidly and merge into a bulklike spectrum at approximately 25 monolayers. An analysis of the peak positions yields a highly accurate bulk band structure of Ag. A very narrow d-band peak width (13 meV) is observed at the band top.

Journal Article↗
PubMed2000

Inhibition of tert-butyl hydroperoxide-induced cell membrane bleb formation by alpha-tocopherol and glutathione.

Multiple bleb formation on cell membrane is common during cell death. The effects of alpha-tocopherol and glutathione (GSH) on tert-butyl hydroperoxide (TBH)-induced membrane changes in rat hepatocytes were studied. Over 60 min of exposure, TBH (0.5-2.0 mM) caused a dose-dependent membrane blebbing. Cells pretreated with buthionine sulfoximine, a GSH synthesis inhibitor, had significantly greater blebbing and lactate dehydrogenase (LDH) leakage under 0.5 mM TBH treatment as compared to cells without pretreatment. However, the protective effect of GSH disappeared when the TBH concentration was increased to 2.0 mM. In the presence of alpha-tocopheryl succinate (TS) pretreatment, it was noted that bleb formation, expressed as the percentage of cells bearing blebs, the average bleb size, or the onset of blebbing, was partially suppressed even when TBH concentration was 2.0 mM. TBH-induced thiobarbituric acid reactive substances and LDH leakage were completely abolished by TS pretreatment. Accompanying bleb formation, membrane-insoluble actin was noted to decrease by immunoblot assay. The decrease in actin was also suppressed by TS. These results indicated that intracellular GSH and alpha-tocopherol status are important to the TBH-induced cell membrane abnormality. Furthermore, TS plays a defensive role against blebbing when GSH is exhausted by TBH.

Actins↗
PubMed1999

Economic transition and changing relation between income inequality and mortality in Taiwan: regression analysis.

OBJECTIVE: To examine the changing relation between income inequality and mortality through different stages of economic development in Taiwan. DESIGN: Regression analysis of mortality on income inequality for three index years: 1976, 1985, and 1995. SETTING: 21 counties and cities in Taiwan. MAIN OUTCOME MEASURES: All age mortality and age specific mortality in children under age 5. RESULTS: When median household disposable income was controlled for, the association between income inequality and mortality became stronger in 1995 than in 1976. Especially, the association between income inequality and mortality in children aged under 5, with adjustment for differences in median household disposable income, changed from non-significant in 1976 to highly significant in 1995. In 1995, the level of household income after adjustment for income distribution no longer had a bearing on mortality in children under 5. CONCLUSION: The health of the population is affected more by relative income than by absolute income after a country has changed from a developing to a developed economy.

Adolescent↗
PubMed1999

Quantum-well states as fabry-Perot modes in a thin-film electron interferometer

Angle-resolved photoemission from atomically uniform silver films on iron (100) shows quantum-well states for absolutely determined film thicknesses ranging from 1 to approximately 100 monolayers. These states can be understood in terms of Fabry-Perot modes in an electron interferometer. A quantitative line shape analysis over the entire two orders of magnitude of thickness range yields an accurate measurement of the band structure, quasiparticle lifetime, electron reflectivity, and phase shift. Effects of confinement energy gap, reflection loss, and surface scattering caused by controlled roughness are demonstrated.

Journal Article↗
PubMed1996

Microbial colonizers in leprosy skin ulcers and intensity of inflammation.

The microflora of 55 patients with leprosy skin ulcers was studied and related to a weighted inflammatory score (IS). The control group consisted of 18 ulcers with different underlying pathology. Leprosy ulcers were characterized by the exclusive presence of two types of branching gram-positive rods; a particular interesting proposal is that Mycobacterium leprae share common antigens with these unusual "leprosy ulcer associated" organisms and group G beta-hemolytic streptococci. In the leprosy group, corynebacteria and branching rods accounted for 97% of gram-positive bacilli and Bacillus species constituted only 3%. In the control group, B. species formed 50% of gram-positive rods; the rest were corynebacteria (p = 0.03). In the leprosy group, one third of the gram-positive bacteria were branching rods; none of them was acid fast. Ten of them were identified as Arcanobacterium haemolyticum, and the remaining 7 could not be identified. The IS of leprosy patients was lower than in the control group. The presence of more than two species of facultative or aerobic gram-negative rods or single species of pyogenic gram-positive cocci correlated with a high IS. The presence of two or more different pyogenic cocci resulted in a lower IS. Further studies into the nature of leprosyunique organisms as well as the inflammation inhibition factors in mixed infections are warranted. It is recommended that management of ulcers should consist of the application of local disinfection and early treatment of episodes of inflammation with a combination of fluoroquinolone and penicillin.

Actinomycetaceae↗