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Biomedical subjects

J L Tang

Publications and source records attributed to J L Tang.

At least 37 records · Page 2Linked to original sources
PubMed2001

Adverse effects of low-level air pollution on the respiratory health of schoolchildren in Hong Kong.

To evaluate the respiratory effects of long-term exposure to air pollution, schoolchildren (ages 8 to 12 years) from two districts in Hong Kong with contrasting air quality were studied. Parents of 1660 children completed questionnaires on respiratory symptoms, and 1294 children had their ventilatory function tested with a spirometer. After adjustment for relevant covariates, children living in the more polluted district had increased odds ratios for frequent cough (1.74), frequent sputum (1.87), chronic sputum (1.84), and doctor-diagnosed asthma (1.98). Children of both sexes in the more polluted district had significantly poorer lung function, and the differences among girls were more marked. The study provides additional evidence for the adverse effects of long-term exposure to relatively low-level air pollution.

Air Pollutants↗
PubMed2001

An efficacy-driven approach to the research and development of traditional Chinese medicine.

Research activities in traditional Chinese medicine have, to date, focused on the search for relevant active substances and mechanisms of action. This research approach is shaped partly by the conventional drug development model, which commences with determining the mechanism of disease, followed by the design and synthesis of therapeutically active compounds or molecules, animal and in vitro studies, and finally clinical trials in humans. Demonstration of clinical efficacy in humans using randomised controlled trials may be a better starting point for research into traditional Chinese medicine, given that these therapies are already in common use. An efficacy-driven approach could avoid basic research into therapies that are clinically ineffective, thus sparing precious research resources.

Evidence-Based Medicine↗
PubMed2001

[Determination of acyclovir in mouse plasma and tissues by reversed-phase high performance liquid chromatography].

The aim of this study was to establish an high performance liquid chromatographic method for determining acyclovir (ACV) concentration in mouse plasma and tissues. A solution of 0.25 mL 60 g/L perchloric acid and 0.25 mL acetonitrile was added into 0.2 mL plasma or 0.2 g tissues to precipitate proteins. Following centrifugation, the supernatant obtained was injected into a reversed-phase column. Operating conditions were Hypersil ODS column(250 mm x 4.6 mm i.d., 5 microns), methanol-water-acetic acid(1:99:0.5, volume ratio) solution as mobile phase at a flow rate of 1.5 mL/min, UV detection at 252 nm. The detection limit of ACV concentration in plasma was 20 micrograms/L and that in tissues was 50 ng/g. The standard curves for ACV were linear in plasma and homogenate of tissues (r > 0.99). The precision of the method was good and the recoveries of ACV were higher than 97.5%. So this method is rapid, accurate and convenient for determination of ACV concentrations in plasma and tissues.

Acyclovir↗
PubMed2000

Charged-particle multiplicity near midrapidity in central Au+Au collisions at sqrt[SNN]=56 and 130 GeV.

We present the first measurement of pseudorapidity densities of primary charged particles near midrapidity in Au+Au collisions at sqrt[s(NN)] = 56 and 130 GeV. For the most central collisions, we find the charged-particle pseudorapidity density to be dN/deta|(|eta|<1) = 408+/-12(stat)+/-30(syst) at 56 GeV and 555+/-12(stat)+/-35(syst) at 130 GeV, values that are higher than any previously observed in nuclear collisions. Compared to proton-antiproton collisions, our data show an increase in the pseudorapidity density per participant by more than 40% at the higher energy.

Journal Article↗
PubMed2000

Weighting bias in meta-analysis of binary outcomes.

This article demonstrates that the weighting-according-to-the-variance method may introduce biases in meta-analyses of binary outcomes. The weighting favors studies that have certain frequencies of outcome events and weights given to studies of the same size may differ tens to thousands of times merely because of variations in the frequency. It also applies different standards to different measures of effect. Thus, the weighting may distort the combined result or even lead to contradictory conclusions when different measures of effect are used. Generally, the bias is more likely to arise when the effect is heterogeneous across the combined trials, the trials are conducted in populations of highly varied risks, the relative risk is used as the effect measure, the effect to be combined is small, any of the trials falls beyond the risk range of 20% and 80%, and/or the number of trials is small. Suggestions for detection and control of the bias are also given.

Bias↗
PubMed2000

Misleading funnel plot for detection of bias in meta-analysis.

Publication and other forms of selection biases pose a threat to the validity of meta-analysis. Funnel plots are usually used to detect such biases; asymmetrical plots are interpreted to suggest that biases are present. Using 198 published meta-analyses, we demonstrate that the shape of a funnel plot is largely determined by the arbitrary choice of the method to construct the plot. When a different definition of precision and/or effect measure were used, the conclusion about the shape of the plot was altered in 37 (86%) of the 43 meta-analyses with an asymmetrical plot suggesting selection bias. In the absence of a consensus on how the plot should be constructed, asymmetrical funnel plots should be interpreted cautiously. These findings also suggest that the discrepancies between large trials and corresponding meta-analyses and heterogeneity in meta-analyses may also be determined by how they are evaluated.

Data Interpretation, Statistical↗
PubMed2000

Characterization of acute myeloid leukemia with MLL rearrangements--no increase in the incidence of coexpression of lymphoid-associated antigens on leukemic blasts.

MLL gene rearrangements are associated with coexpression of myeloid- and lymphoid-associated antigens on leukemic blasts and a dismal outcome in acute lymphoblastic leukemia (ALL). Whether the same conditions can apply to acute myeloid leukemia (AML) is not quite clear. Rearrangements of the MLL gene were analyzed on 113 patients with newly diagnosed de novo AML in a single institution. Sixteen (14%) of them showed rearranged bands by Southern blot analysis, including three (50%) of six infants, three (14%) of 21 children between 1 and 15 years and 10 (12%) of 86 adults. MLL rearrangements were not only detected in M5 (four of 12 patients, 33%) and M4 (six of 31, 19%) subtypes but also in other non-M4-M5 AML (six of 70, 9%), including M1, M2 and M7, but not M3 subtype. Seven patients had chromosomal abnormalities involving 11q23, but nine did not. The latter comprised three (6%) of 48 patients with normal karyotype, one with t(8;21), none with t(15;17), inv(16) or t(9;22), and four (15%) of 27 with cytogenetic aberrations other than those specific structural abnormalities. In contrast to ALL, AML patients with MLL rearrangements did not tend to coexpress lymphoid- and myeloid-associated antigens simultaneously on leukemic blasts and have similar outcome as those without the gene rearrangements.

Acute Disease↗
PubMed1999

Transcriptional regulation of endothelial nitric-oxide synthase by an interaction between casein kinase 2 and protein phosphatase 2A.

We previously demonstrated that lysophosphatidylcholine up-regulated endothelial nitric-oxide synthase promoter activity by increasing Sp1 binding via the action of protein serine/threonine phosphatase 2A (Cieslik, K., Zembowicz, A., Tang, J.-L., and Wu, K.K. (1998) J. Biol. Chem. 273, 14885-14890). To characterize the regulation of basal endothelial nitric-oxide synthase promoter activity and the signaling pathway through which lysophosphatidylcholine augments endothelial nitric-oxide synthase transcription, we used a casein kinase 2 inhibitor coupled with immunoprecipitation to demonstrate that basal Sp1 binding and endothelial nitric-oxide synthase promoter activity were controlled by casein kinase 2 complexed with protein serine/threonine phosphatase 2A. Casein kinase 2 catalyzed protein serine/threonine phosphatase 2A phosphorylation thereby inhibiting its activity. Lysophosphatidylcholine selectively activated p42/p44 mitogen-activated protein kinase. Purified extracellular regulated kinase 2 blocked casein kinase 2 activity and increased protein serine/threonine phosphatase 2A activity, resulting in an increased Sp1 binding and endothelial nitric-oxide synthase promoter activity. These results indicate that Sp1 binding to its cognate site on the endothelial nitric-oxide synthase promoter and its transactivation of endothelial nitric-oxide synthase is regulated by post-translational Sp1 phosphorylation and dephosphorylation through a dynamic interaction between casein kinase 2 and protein serine/threonine phosphatase 2A.

Casein Kinase II↗
PubMed1999

Extramedullary relapse after all-trans retinoic acid treatment in acute promyelocytic leukemia--the occurrence of retinoic acid syndrome is a risk factor.

All-trans retinoic acid (ATRA) is now a standard agent for remission induction of acute promyelocytic leukemia (APL). Recently, extramedullary relapse, which was a rare condition in APL patients after chemotherapy alone, was reported with an increased frequency after ATRA treatment. However, it is not yet clear whether ATRA truly increases the risk of extramedullary recurrence and what are the risk factors. In this study, three of 13 patients with recurrent APL after prior treatment of ATRA were found to have extramedullary involvement, compared with none in 11 recurrent patients previously treated with chemotherapy alone (estimated relative risk 2.100, 95% confidence interval 1.341-3.289). Furthermore, in the former group of patients, the development of retinoic acid (RA) syndrome during prior induction treatment was significantly associated with extramedullary involvement at relapse (three in five patients with RA syndrome vs none in eight without the syndrome, estimated relative risk 5.000, 95% confidence interval 1.448-17.271). In conclusion, ATRA may predispose APL patients to extramedullary involvement at relapse and the occurrence of RA syndrome is a risk factor for it. Further studies are needed to confirm these findings. It also remains to be clarified whether treatment modification is necessary in patients who develop RA syndrome during ATRA treatment.

Adolescent↗
PubMed1999

Minimally differentiated acute myeloid leukemia in Taiwan: predominantly occurs in children less than 3 years and adults between 51 and 70 years.

Acute myeloid leukemia (AML) with minimal differentiation was usually referred to as acute undifferentiated leukemia in the past. With the help of immunophenotyping, this subtype of leukemia was shown to express myeloid antigens on the blasts and was designated AML-M0 by FAB Cooperative Study Group in 1991. Among the 423 consecutive newly diagnosed de novo AML at our institution, 12 (2.8%) were of M0 subtype. The proportion of M0 in AML was higher in children than in adults (8.2% vs 1.7%). Four other M0 patients referred from outside hospitals for immunophenotyping were also included in this study. There were two peaks in age distribution of these 16 patients: less than 3 years and between 51 and 70 years, respectively. Organomegaly was more common in patients with AML-M0 than in those with other subtypes (56.3% vs 29.2%, P = 0.025). The former patients had higher incidences of CD7 and CD34 expression on the leukemic cells than the latter ones (50% vs 16.9%, P = 0.003 and 69.2% vs 37.9%, P = 0.019, respectively). The patients with AML-M0 showed more frequent clonal chromosomal abnormalities in the leukemic cells than other AML patients (83.3% vs 53.9%, P = 0.039); the same is also true for complex cytogenetic aberrations (50% vs 11. 4%, P = 0.004). Adults with AML-M0 showed a lower complete remission (CR) rate and significantly poorer survival than those with non M0-AML. However there was no significant difference in outcome between the two groups of pediatric patients. In conclusion, AML-M0 is a unique subtype of leukemia that has distinct age distribution and shows different clinical and biological characteristics from other AML. Adult patients have poor prognosis. Whether pediatric patients had better outcome than adults needs to be clarified in further studies.

Acute Disease↗
PubMed1999

Persistent leucocyte abnormalities in children years after previous long-term low-dose radiation exposure.

Two hundred and eighty-nine children who had been educated in a kindergarten during 1983-92 and received continuous low-dose whole body gamma-irradiation from 60Co-contaminated steel window frames in their classrooms were investigated for residual effects on their haematological tissues. Another 751 children, sex and age-matched, received similar but much lower exposure in an elementary school with classrooms built with contaminated steel rebars. The peripheral leucocytes of these children were examined 5-7 years after they had stopped using these irradiated classrooms. Children who received higher exposure in the kindergarten were shown to have a significant decrease in total leucocytes and neutrophils and an increase in eosinophils. Moreover, they were shown to be at significantly higher risk of developing relative leucopenia and neutropenia, but not lymphocytopenia, than those who received a lower exposure at the elementary school. Children from the kindergarten who had much higher exposure were shown to have a significant lowering of total leucocytes and neutrophils, and an increase in eosinophils years after exposure. Residual adverse haematological effects on the exposed children are strongly suspected.

Adolescent↗
PubMed1999

Smoking and mortality in an older Chinese cohort.

OBJECTIVES: Only limited data are available regarding smoking and health in later life and, in particular, in the older Chinese population. This paper reports the relationship between smoking and mortality in a Chinese cohort aged 70 years and older. SETTING: A population-based study conducted in Hong Kong. PARTICIPANTS: A cohort comprising 2030 subjects aged 70 and older were assembled in 1991-1992 and followed for 36 months. DESIGN: A prospective cohort study. MEASUREMENTS: Baseline information regarding smoking status as well as several social and health variables were obtained through face-to-face interview at the respondent's place of residence. The outcome variables were mortality from all causes as well as from cancer and cardiovascular and respiratory diseases. Causes of death were ascertained from death certificates. RESULTS: The prevalence rates of smoking at baseline were 24.9% in men and 8.2% in women. A total of 534 deaths occurred during the 36-month follow-up period. Of these, 447 were attributable to three main causes: cancer, cardiovascular disease, and respiratory disease. Elevated mortality risks from all causes were observed among both male (RR = 1.4; 95% CI, 0.9-1.9) and female (RR = 1.6; 95% CI, 1.0-2.5) current smokers, but the 95% confidence intervals overlapped. Significant association between current smoking and combined mortality from these three major causes was found in men; it was also found in women after excluding those with these diseases at baseline. More than a 3-fold increased risk of cancer mortality was found in current smokers of both sexes. Although nonsignificant associations were found between former smokers and mortality risks in men, women who were former smokers had increased mortality risks from all causes as well as from cancer and respiratory diseases. CONCLUSIONS: This 3-year prospective study of an older Chinese cohort reveals the impact of smoking on health during later life, especially in women. Smoking cessation, particularly in older men, should be beneficial in reducing mortality. Smoking cessation should begin as early as possible for women.

Aged↗
PubMed1999

Allogeneic stem cell transplantation for patients with high-risk myelodysplastic syndrome.

Allogeneic stem cell transplantation (allo-SCT) is the only treatment with curative potential for patients with myelodysplastic syndrome (MDS). From June 1986 to April 1997, we treated 12 patients with primary MDS (5 men, 7 women, median age, 36.5 years) by allo-SCT. All patients had one or more of the following poor prognostic factors: intermediate-2 or high-risk categories according to the International Prognostic Scoring System; disease progression during follow-up; heavy transfusion requirements and recurrent infections. The median duration from diagnosis of MDS to allo-SCT was 6 months. The preconditioning regimen included total body irradiation combined with either high-dose cytarabine (n = 6), high-dose cyclophosphamide (n = 4), or other regimens (n = 2). Ten patients received bone marrow transplantations and two patients received peripheral blood stem cell transplantations. Prophylaxis for graft-versus-host disease (GVHD) consisted of standard cyclosporin and short-course methotrexate. Acute GVHD of grade 2 or above occurred in 10 patients, while chronic GVHD occurred in seven of the nine patients who survived longer than 6 months after allo-SCT. With a median follow-up of 50 months, all nine patients with human leukocyte antigen (HLA)-matched sibling donors survived. One patient had a relapse 6 months after transplantation and achieved complete remission again with low-dose cytarabine therapy. The three patients receiving allo-SCT from unrelated or HLA-mismatched donors died of grade 3 to 4 acute GVHD and infection within 5 months after transplantation. The estimated disease-free survival at 4 years was 67% (95% confidence interval, 40-93%), and the overall survival was 75% (95% confidence interval, 50-99%). Our data suggest that allo-SCT should be considered early in the clinical course for young MDS patients with a poor prognosis and a matched sibling donor.

Adult↗