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Y T Wang

Publications and source records attributed to Y T Wang.

At least 37 records · Page 2Linked to original sources
PubMed2005

Identification and quantitation of eleven sesquiterpenes in three species of Curcuma rhizomes by pressurized liquid extraction and gas chromatography-mass spectrometry.

In this paper, GC-MS and pressurized liquid extraction (PLE) was developed for identification and quantitative determination/estimation 11 sesquiterpenes including germacrene D, curzerene, gamma-elemene, furanodienone, curcumol, isocurcumenol, furanodiene, germacrone, curdione, curcumenol and neocurdione in Ezhu which are derived from three species of Curcuma, i.e., Curcuma phaeocaulis, Curcuma wenyujin and Curcuma kwangsiensis by using an analogue as standard. The results showed the methodology could quantitatively compare the quality of three species of Curcuma. The contents of investigated sesquiterpenes in three species of Curcuma were high variant. Hierarchical clustering analysis based on characteristics of 11 identified peaks in GC profiles showed that 18 samples were divided into two main clusters, C. phaeocaulis and C. wenyujin, respectively. C. kwangsiensis showed the characters closed to C. phaeocaulis or C. wenyujin based on its location. Five components such as furanodienone, germacrone, curdione, curcumenol and neocurdione were optimized as markers for quality control of Ezhu.

Chemistry, Pharmaceutical↗
PubMed2005

Contact screening and latent TB infection treatment in Singapore correctional facilities.

SETTING: Singapore, a city-state with a tuberculosis (TB) incidence rate of 47 per 100000 population in 2000. OBJECTIVES: 1) To report our experience with contact investigation and latent TB infection (LTBI) treatment in high-risk contacts with unknown human immunodeficiency virus (HIV) status in correctional facilities (CFs) (prisons/drug rehabilitation centres); and 2) to compare the yield of contact screening in this setting with that in the community (household/family) setting. METHODS: The tuberculin skin test (TST) readings of 704 CF contacts screened from 1999 to 2001 were compared with those of 2729 household/family contacts who underwent screening in 2000. RESULTS: Respectively eight (1.1%) and 20 (0.7%) active TB cases were detected among the CF and community contacts. A significantly higher proportion of CF contacts had first (non-conversion) TST readings > or =15 mm (39% vs. 22%, OR 2.3; 95%CI 1.9-2.7; P < 0.001), and 10-14 mm (26% vs. 18%, OR 1.6; 95%CI 1.3-2.0; P < 0.001) and TST conversion (43% vs. 20%, OR 2.9; 95%CI 1.7-4.9; P < 0.001). LTBI treatment was started in 65% of the CF contacts screened; 87% completed treatment. CONCLUSION: We found a high LTBI rate among CF contacts, presenting an opportunity for intervention.

Adult↗
PubMed2004

Simultaneous determination of six main nucleosides and bases in natural and cultured Cordyceps by capillary electrophoresis.

A simple method is described for simultaneous determination of six main nucleosides and bases including adenine, uracil, adenosine, guanosine, uridine and inosine in Cordyceps by capillary electrophoresis (CE). Chemometric optimization based on central composite design was employed to find the optimum resolution. The optimum factor space was defined by three parameters: buffer concentration, pH and concentration of acetonitrile as organic modifier. Resolution (Rs) was employed to evaluate the response function. A running buffer composed of 500 mM boric acid, adjusted pH to 8.6 with sodium hydroxide and 12.2% acetonitrile as modifier was found to be the most appropriate for the separation. The contents of the six components were determined by using adenosine monophosphate as an internal standard. Furthermore, hierarchical clustering analysis based on characteristics of 32 peaks in CE profiles from the tested 12 samples showed that natural and cultured Cordyceps were in different clusters. Adenosine and inosine were extracted as markers for discrimination of natural Cordyceps. The result of clustering based on the two peaks characteristics was in excellent agreement with that based on 32 peaks'. Thus, adenosine and inosine could be used as markers for quality control of natural and cultured Cordyceps.

Buffers↗
PubMed2004

Simultaneous determination of ergosterol, nucleosides and their bases from natural and cultured Cordyceps by pressurised liquid extraction and high-performance liquid chromatography.

A simple method is described for the simultaneous determination of ergosterol, nucleosides and their bases in Cordyceps. The samples were extracted by using pressurised liquid extraction (PLE). The effects of experimental variables, such as solvent, temperature, static extraction time and cycles, on PLE efficiency have been studied. The results showed a strong influence of the solvent and temperature on extraction efficiency of PLE. The determination was achieved by high-performance liquid chromatography (HPLC) using a Zorbax NH2 analytical column (250 x 4.6 mm i.d., 5 microm) with diode-array detector (DAD). The automated preparation of the sample permits a very fast analysis which is an important goal for routine purpose.

Chromatography, High Pressure Liquid↗
PubMed2004

Treatment of latent TB infection for close contacts as a complementary TB control strategy in Singapore.

OBJECTIVE: To describe our initial experience with treatment of latent tuberculosis infection (LTBI) for close contacts of infectious TB cases in Singapore, an intermediate TB burden country with mass BCG (re)vaccination since the 1950s. METHODS: Screening of 5699 contacts of 1374 index cases notified in 1998 was carried out at the TB Control Unit. RESULTS: Seventy-five per cent (4239) completed tuberculin skin testing (TST). Fifty-three cases of TB disease were detected (0.9% yield). Twenty-one per cent (895/4239) of the TST-screened contacts were started on LTBI treatment, comprising 92% (810/883) of contacts with TST > or = 15 mm, 5% (64/1195) of those with TST 10-14 mm and 1% (21/2161) of those with TST < 10 mm. The regimen utilized was isoniazid for 6 months in adults and 9 months in children. Eighty-one per cent completed treatment. The incidence of isoniazid-induced hepatitis was 0.45%. Over the ensuing 4 years, one case of active TB was reported among those treated for LTBI, and 10 cases (five without TST readings) were notified among contacts who did not receive treatment. CONCLUSIONS: Where good case-finding and treatment of TB disease exist, and where resources permit, LTBI treatment for close contacts is feasible as a complementary TB control strategy in an intermediate TB burden country with a BCG-vaccinated population.

Adjuvants, Immunologic↗
PubMed2003

Survival among Chinese women with lung cancer in Singapore: a comparison by stage, histology and smoking status.

Lung cancer generally carries a poor prognosis and the determinants of survival have been of interest. However, survival estimates in Asian populations are scarce. This study describes survival rates and their determinants in Singapore Chinese women, a primarily non-smoking population. Three hundred and twenty-six Chinese women, diagnosed with primary lung carcinoma in three major hospitals in Singapore between April 1996 and December 1998, were followed up till 31 December 2000. The Kaplan-Meier method was used for survival analysis. Two hundred and eighty (85.7%) died from the disease during follow-up. The median survival time was 0.7 years and the three-year survival was 15.8%. These survival rates are similar to those of Western populations, and they provide a basis for examining trends over time. Age at diagnosis was an independent prognostic factor [adjusted hazard ratio (relative risk) 1.4, 95% confidence intervals (CI) 1.1-1.9 for women above 65 years relative to younger women]. Most (70.5%) tumours were stage III/IV at diagnosis. Three-year survival ranged from 72% among patients with stage I tumours to 7% for stage IV tumours. Overall, there was no survival difference among different histological types in all stages combined. When limited to stages I and II cancers, adenocarcinomas were associated with a better outcome relative to other histological subtypes combined (adjusted relative risk 0.4, 95% CI 0.1-1.0). Smoking was an independent risk factor (adjusted relative risk 1.3, 95% CI 1.0-1.8). Nevertheless, non-smokers comprised 57.4% of this series, highlighting the importance of increased awareness among health professionals and the public that lung cancer is not only a disease of smokers. The high proportion of late-stage tumours in this study and the impact of disease stage on outcome underline the importance of early detection in improving survival of lung cancer.

Adult↗
PubMed2003

Antinociceptive effect of calcitonin gene-related peptide in the central nucleus of amygdala: activating opioid receptors through amygdala-periaqueductal gray pathway.

The central nucleus of amygdala (CeA) plays an important role in pain regulation. Calcitonin gene-related peptide (CGRP)-like immunoreactive fibers and CGRP receptors are distributed densely in CeA. The present study was performed to elucidate the role of CGRP in nociceptive regulation in the CeA of rats. Intra-CeA injection of CGRP induced dose-dependent increases in the hind-paw withdrawal latency tested by hotplate test and Randall Selitto Test, indicating an antinociceptive effect of CGRP in CeA. Furthermore, the antinociceptive effect of CGRP was blocked by intra-CeA administration of the CGRP receptor antagonist CGRP8-37, suggesting that CGRP receptor1 is involved in the CGRP-induced antinociception. The CGRP-induced antinociception was attenuated by s.c. injection of the opioid antagonist naloxone, suggesting an involvement of endogenous opioid systems in CGRP-induced antinociception. Moreover, it was demonstrated that opioid receptors in the periaqueductal gray, but not in CeA, contributed to the CGRP-induced antinociception, indicating the importance of the pathway between CeA and the periaqueductal gray in CGRP-induced antinociception. Combining retrograde fluorescent tracing with immunohistochemistry, we found that met-enkephalinergic neurons were innervated by CGRP-containing terminals in CeA. Furthermore, most neurons in the CeA retrogradely traced from the periaqueductal gray were contacted by CGRP-containing terminals and some of them were surrounded by characteristic basket-like structures formed by the terminals, suggesting that CGRP innervates the neurons which project from CeA to the periaqueductal gray. The results indicate that CGRP activates the met-enkephalinergic neurons, which project from CeA to the periaqueductal gray, producing antinociceptive effect in rats.

Amygdala↗
PubMed2003

Performance of the rapidly extracted auditory evoked potentials index to detect the recovery and loss of wakefulness in anesthetized and paralyzed patients.

BACKGROUND: The rapidly extracted auditory evoked potentials index (A-lineTM ARX Index or AAI) has been proposed as a method to measure the depth of anesthesia. A prospective study was designed to assess the performance of AAI to detect the recovery and loss of wakefulness in anesthetized and paralyzed patients. METHODS: Fourteen adult patients undergoing elective surgery were anesthetized with propofol 1.5 mg kg-1, vecuronium 0.1 mg kg-1 and further propofol 1.0 mg kg-1. Wakefulness was measured by the ability of the patient to respond to command using the isolated forearm technique (IFT). After the patient responded, propofol was infused at 10 mg kg-1. h-1 until wakefulness (responsiveness) was lost. The AAI was recorded continuously throughout the study and analyzed off-line. RESULTS: The AAI showed a significant difference between the values registered during, 30 s before and 30 s after the recovery, and also between 30 s before and 30 s after the loss of wakefulness. The prediction probability (Pk) values for AAI were 0.786 and 0.864 during the transitions from unresponsiveness to responsiveness and from responsiveness to unresponsiveness. The area under the receiver operating characteristic curve for the responsive and unresponsive values was 0.926 (SE 0.002, 95% CI 0.922-0.931), and the AAI values of approximately 5%, 50% and 95% predicted probability of wakefulness were 19, 29 and 39, respectively. CONCLUSION: The AAI may be a good predictor of recovery and loss of wakefulness for anesthetized and paralyzed patients.

Adult↗
PubMed2003

Species-specific PCR primers for Pythium developed from ribosomal ITS1 region.

AIMS: To develop a specific method for distinguishing and detecting Pythium species. METHODS AND RESULTS: Twenty PCR primers were designed from the sequences of the rDNA internal transcribed spacer 1 (ITS1) region from 34 Pythium species. The specificity of these forward primers paired with ITS2 or ITS4 and reverse universal primers was tested. Five species-specific primers were obtained, other primers showed different specificity to Pythium species. The specific amplifications enabled nine Pythium species to be differentiated. Specific detection of Pythium aphanidermatum from infested plants and P. dimorphum from soil was demonstrated. CONCLUSIONS: A method for identifying nine Pythium species using specific PCR amplification was achieved. SIGNIFICANCE AND IMPACT OF THE STUDY: Because of its rapidness and ease, the results of PCR amplified with different primers can be a powerful method for identifying Pythium species and detecting or monitoring the target fungus directly from plant material, soil and water samples.

Base Sequence↗
PubMed2002

White spot syndrome virus (WSSV) infects specific hemocytes of the shrimp Penaeus merguiensis.

White spot syndrome virus (WSSV) was specifically detected by PCR in Penaeus merguiensis hemocytes, hemolymph and plasma. This suggested a close association between the shrimp hemolymph and the virus. Three types of hemocyte from shrimp were isolated using flow cytometry. Dynamic changes of the hemocyte subpopulations in P. merguiensis at different times after infection were observed, indicating that the WSSV infection selectively affected specific subpopulations. Immunofluorescence assay (IFA) and a Wright-Giemsa double staining study of hemocyte types further confirmed the cellular localization of the virus in the infected hemocytes. Electron microscopy revealed virus particles in both vacuoles and the nucleus of the semigranular cells (SGC), as well as in the vacuoles of the granular cells (GC). However, no virus could be detected in the hyaline cells (HC). Our results suggest that the virus infects 2 types of shrimp hemocytes--GCs and SGCs. The SGC type contains higher virus loads and exhibits faster infection rates, and is apparently more susceptible to WSSV infection.

Animals↗
PubMed2002

Detection of white spot syndrome virus (WSSV) of shrimp by means of monoclonal antibodies (MAbs) specific to an envelope protein (28 kDa).

The vp28 gene encoding an envelope protein (28 kDa) of white spot syndrome virus (WSSV) was amplified from WSSV-infected tiger shrimp that originated from Malaysia. Recombinant VP28 protein (r-28) was expressed in Escherichia coli and used as an antigen for preparation of monoclonal antibodies (MAbs). Three murine MAbs (6F6, 6H4 and 9C10) that were screened by r-28 antigen-based enzyme-linked immunosorbent assay (ELISA) were also able to recognize viral VP28 protein as well as r-28 on Western blot. Three non-overlapping epitopes of VP28 protein were determined using the MAbs in competitive ELISA; thus, an antigen-capture ELISA (Ac-ELISA) was developed by virtue of these MAbs. Ac-ELISA can differentiate WSSV-infected shrimp from uninfected shrimp and was further confirmed by a polymerase chain reaction (PCR) and Western blot. Approximately 400 pg of purified WSSV sample and 20 pg of r-28 could be detected by Ac-ELISA, which is comparable in sensitivity to PCR assay but more sensitive than Western blot in the detection of purified virus. Hemolymph and tissue homogenate samples collected from a shrimp farm in Malaysia during December 2000 and July 2001 were also detected by Ac-ELISA and PCR with corroborating results.

Animals↗
PubMed2002

Cardiac output increases prior to development of pulmonary edema after re-expansion of spontaneous pneumothorax.

Pulmonary edema following reexpansion of spontaneous pneumothorax is an uncommon complication. The underlying mechanism of this condition is unclear. We report the hemodynamic characteristics in a series of 7 male patients with spontaneous large (>50%) pneumothoraces of > or = 24 h and correlate the changes with reexpansion pulmonary edema (REPE). A pulmonary artery floatation catheter was inserted and hemodynamic data were obtained before therapeutic chest tube insertion, 1 h after chest tube insertion and the following day. Four (57%) patients developed REPE. There was a tendency for larger pneumothorax to develop REPE. Capillary wedge pressure did not change significantly 1 h after the insertion of chest tube in all our patients. Cardiac output increased significantly in patients who developed REPE compared to those who did not (+ 1.06 l/min vs -0.27 l/min; P = 0.03) 1 h after insertion of chest tube. One patient did not develop pulmonary edema despite having a large (> 80%) pneumothorax. His cardiac output did not rise 1 h after chest tube insertion. REPE is not an uncommon complication following chest tube drainage in patients with large and long-standing pneumothorax. The increase in cardiac output after chest tube insertion may be associated with subsequent development of REPE.

Adult↗
PubMed2002

Changes in the rapidly extracted auditory evoked potentials index and the bispectral index during sedation induced by propofol or midazolam under epidural block.

BACKGROUND: The bispectral index (BIS) and the rapidly extracted auditory evoked potentials index (A-line ARX Index or AAI) have been proposed as methods to measure the depth of sedation. A prospective study was designed to assess the performance of both these methods for measuring the depth of sedation induced by propofol or midazolam under epidural block. METHODS: Thirty-two ASA I and II adult patients undergoing elective gynaecological surgery under low-thoracolumbar epidural block were studied. Eighteen patients received propofol (Group P: 20 mg bolus every 3 min) and 14 received midazolam (Group M: 0.5 mg bolus every 5 min) until an observer's assessment of alertness/sedation (OAA/S) scale score of 1 was achieved. AAI and BIS were monitored for different OAA/S scores. RESULTS: AAI and BIS decreased and increased following the changes on the patients' OAA/S scores and correlated with sedation significantly. During the onset phase, the coefficients of Spearman's rank correlation for AAI and BIS were respectively 0.958 and 0.898 (P < 0.001) for Group P, and 0.973 and 0.945 (P < 0.001) for Group M. During the recovery phase in Group P, the coefficients were respectively 0.946 and 0.702 (P < 0.001). Linear regression analysis showed that both AAI and BIS were linearly related to the OAA/S scores. The coefficients of Spearman's rank correlation and linear regression for AAI were all greater than those for BIS (P < 0.05). CONCLUSIONS: Both AAI and BIS correlated well with the depth of sedation induced by propofol or midazolam under epidural block. AAI may be more valuable when monitoring depth of sedation.

Adult↗
PubMed2002

Bacteriologically-negative pulmonary tuberculosis--the Singapore tuberculosis control unit experience.

INTRODUCTION: Patients with radiological features suggestive of active pulmonary tuberculosis (PTB) from areas with a high prevalence of the disease have a high clinical likelihood of PTB regardless of the bacteriological findings. It is the established practice in many countries to initiate therapy in such patients. Our study aimed to determine if treatment for bacteriologically-negative PTB in our local population was appropriate and to identify features at presentation that would be predictive of active PTB, as defined by good and appropriate response to anti-tuberculous treatment. MATERIALS AND METHODS: A retrospective review of a randomised sample consisting of 100 bacteriologically-negative PTB patients given a course of anti-tuberculous treatment at the Singapore Tuberculosis Control Unit (TBCU). Based on their treatment response and outcome, patients were classified as probable active or unlikely active PTB. Patients' characteristics, clinical presentation and radiological findings were analysed for their association with likelihood of probable active PTB. RESULTS: Fifty-six per cent of patients in this study had probable active PTB. The decision to treat this group of patient was appropriate. There was no serious adverse reaction in the patients treated. The presence of symptoms, especially cough at presentation, a history of contact with tuberculosis and cavitation on chest radiograph, were associated with an increase risk of probable active disease. CONCLUSION: The TBCU's practice to treat patients suspected of having radiological PTB in the setting of negative sputum smear and culture seems to be appropriate in the majority of cases.

Adult↗
PubMed2002

Hepatotoxicity of tuberculosis chemotherapy under general programme conditions in Singapore.

SETTING: The Singapore Tuberculosis (TB) Control Unit, a high volume national referral centre. OBJECTIVES: To determine the incidence, clinical course and outcome of TB drug-induced hepatitis (DH) and the risk factors associated with DH under general programme conditions. DESIGN: A retrospective review of adult patients started on TB treatment in 1998. RESULTS: There were 55 cases of DH in the cohort of 1036 patients treated in 1998. The median time to diagnosis of DH was 38 days. Factors significantly associated with DH were abnormal baseline transaminases/ bilirubin (OR 2.1, 95%CI 1.1-4.3, P = 0.02), age >60 years (OR 1.97, 95%CI 1.14-3.34, P = 0.01) and female sex (OR 1.9, 95%CI 1.07-3.4, P = 0.02). Ethnicity, self-reported alcohol consumption and body weight were not associated with development of DH. All three patients with fatal DH had received pyrazinamide-containing regimens. Treatment was re-introduced in 48 patients and successfully completed in 45 patients. The median time to reinstitution of TB treatment was 23 days. CONCLUSION: The incidence of TB drug-induced hepatitis was 5.3%. Age >60 years, abnormal baseline transaminase/bilirubin levels and female sex were risk factors associated with the development of TB drug-induced hepatitis.

Alanine Transaminase↗
PubMed2002

An assessment of the role of exhaled carbon monoxide in acute asthmatic exacerbations in hospitalised patients.

Exhaled carbon monoxide is a useful marker of airway inflammation in untreated asthma. Whether exhaled CO is clinically useful in steroid treated patients in a hospital setting is uncertain. We therefore studied exhaled CO as a marker of asthma severity in clinical practice. Non-smoking "acute" asthmatics (hospitalised; n=33), "stable" asthmatics (n=35), and healthy controls (n=22) were recruited. Exhaled CO, peak expiratory flow (PEF) and FEV1 were measured daily (hospitalised cases) or once only (stable outpatients). Inpatients were managed without knowledge of the results. Exhaled CO levels in acute asthmatics (initial levels), stable asthmatics and controls were similar (median=2.0 ppm, h=5.05, p=0.08). In acute asthmatics, initial exhaled CO did not correlate with duration of hospitalisation, doses of intravenous corticosteroids, doses of nebulised salbutamol, PEF (% predicted) or FEV1 (% predicted). In stable asthmatics, exhaled CO did not correlate with corticosteroid dosage, PEF (% predicted) or FEV1 (% predicted). In the setting of acute hospitalised asthma patients, exhaled CO may not add any further to clinical management. This may in part be due to prior treatment with corticosteroids.

Acute Disease↗
PubMed2001

Interpretation of the tuberculin skin test in Mycobacterium bovis BCG-vaccinated Singaporean schoolchildren.

Tuberculin skin test (TST) interpretation in Singapore is confounded by universal BCG vaccination at birth and by a revaccination policy for schoolchildren who are tuberculin nonreactors (TST < 10 mm, using 1 TU PPD RT 23) at 12 or 16 yr old, with not more than two BCG vaccinations given to any child. School health records for birth cohorts 1978 to 1984 indicate that 82.8% were revaccinated at age 12 yr. By collation with the national database of tuberculosis (TB) notifications, we examined the risk of TB disease in these cohorts for the 4 yr subsequent to TST reading at ages 12 and 16 yr respectively, in intervals of 0-4, 5-9, 10-14, 15-17, and >/= 18 mm. Receiver-operating curves (ROCs) were constructed to ascertain the optimum TST cutoffs in screening for the likelihood of development of TB disease. A cutoff of 10 mm performed best for the group tested at age 12 yr, whereas 16 mm was found to be optimum in those tested at age 16 yr (> 80% of whom were BCG revaccinated 4 yr earlier). We have extrapolated these findings to the screening of contacts, and utilized these cutoff points to guide the treatment of latent TB infection in this high-risk group.

Adolescent↗