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T Hsieh

Publications and source records attributed to T Hsieh.

66 records · Page 4Linked to original sources
PubMed1976

Physicochomecial studies on interactions between DNA and RNA polymerase. Isolation and mapping of a T7 DNA fragment containing the early promoters for Escherichia coli RNA polymerase.

The cleavage sites in the early promoter region of coliphage T7 have been mapped for four restriction enzymes. They are, from the left end in base pairs, 1100 and 740 for Hinf; 680, 320, 530, 240, 77, and 67 for Hind II; 620 and 530 for Hpa II; 790 for Alu I. The nucleotide sequence between the Hind II site at 680 base pairs from the left end and the Hinf site at 740 base pairs from the left end has been determined, from which the start point of the promoter A3 is located at 720 base pairs from the left end. The start points of the other two major promoters A1 and A2 are deduced to be at 460 and 580 base pairs from the left end, respectively, from the chain lengths of the in vitro transcripts off the 1100 base-pairs long Hinf fragment. Similar to the sequences of a pL and pR promotors of phage lambda and a sequence in Simian Virus 40 used by Escherichia coli RNA polymerase as a promotor, the sequence of the A3 promotor of T7 also has a Hind II restriction site approximately 30 base pairs upstream to the start point of RNA synthesis. No such Hind II sites exist, however, for the A1 and A2 promoters. Experiments on the protection of some of the restriction sites on the 1100 base-pairs-long Hinf fragment by RNA polymerase binding support the electron microscopic observations of others that, in addition to the three sites A1, A2 and A3, there is at least a fourth site at which E. coli RNA polymerase can bind strongly. In addition to the Hind II site at 680 base pairs from the left end and the Hinf site at 740 base pairs from the left end, which are presumably protected by the binding of a single RNA polymerase at the A3 site, the Hind II site at 240 base pairs from the left end is also protected at a level of 5 polymerase molecules/DNA fragment. The possible existence of several minor promotor sites in the early promotor region, in addition to the three major promotor sites, is discussed.

Base Sequence↗
PubMed1976

Nasopharyngeal carcinoma and Epstein-Barr virus. III. The detection of anti-nuclear antibodies.

The presence of anti-nuclear antibodies (ANA) has been studied in 433 sera from 305 patients with anaplastic nasopharyngeal carcinoma (NPC) in Taiwan, by means of indirect fluorescent antibody method. Another 134 sera from normal adults or from patients with other diseases served as controls. Patients with NPC showed positive rate of 23.1%. Forty-two patients with other malignant and 25 patients with benign tumors of the head and neck showed positive rates of 9.5% and 8.0%, respectively. Forty-eight patients with inflammatory diseases and 19 normal adults were negative. The presence of ANA in 103 NPC patients before treatment was analyzed in detail. The positive rate was not significantly influenced by the age and sex of the patients, by the duration of the disease, by the extent of primary tumor and the presence of neck metastasis. But the positive rate rose as the anti-EB-VCA titer increased. This positive correlation of ANA and anti-EB-VCA antibodies was also significant in all the NPC sera. During and at the end of irradiation therapy, the ANA positive rates showed no remarkable variation. After treatment of the disease, ANA positive rate decreased gradually and this reduction became apparent after three years of remission of the disease. But the presence of ANA in NPC patients was not related to the prognosis of the patients. The possible mechanism in production of ANA in NPC patients was discussed with special reference to EB virus.

Adult↗
PubMedDate not supplied

Phosphatidylinositol 3-kinase is required for insulin-like growth factor-I-induced vascular smooth muscle cell proliferation and migration.

Insulin-like growth factor-I (IGF-I) plays an important role in regulating vascular smooth muscle cell (VSMC) proliferation and directed migration. The mitogenic and chemotactic actions of IGF-I are mediated through the IGF-I receptor, but how the activation of the IGF-I receptor leads to these biological responses is poorly understood. In this study, we examined the role of phosphatidylinositol 3-kinase (PI3 kinase) in mediating the mitogenic and chemotactic signals of IGF-I. IGF-I treatment resulted in a significant increase in phosphotyrosine-associated PI3 kinase activity in cultured primary VSMCs. To determine whether insulin receptor substrate (IRS)-1, -2, or both are involved in IGF-I signaling in VSMCs, cell lysates were immunoprecipitated with either an anti-IRS-1 or an anti-IRS-2 antibody, and the associated PI3 kinase activity was determined. IGF-I stimulation resulted in a significant increase in IRS-1- but not IRS-2-associated PI3 kinase activity, suggesting that IGF-I primarily utilizes IRS-1 to transmit its signal in VSMCs. The IGF-I-induced increase in IRS-I-associated PI3 kinase activity was concentration dependent. At the maximum concentration (50 ng/mL), IGF-I induced a 60-fold increase. This activation occurred within 5 minutes and was sustained at high levels for at least 6 hours. IGF-I also caused a concentration-dependent and long-lasting activation of protein kinase B (PKB/Akt). Inhibition of PI3 kinase activation by LY294002 or wortmannin abolished IGF-I-stimulated VSMC proliferation and reduced IGF-I-directed VSMC migration by approximately 60%. These results indicate that activation of PI3 kinase is required for both IGF-I-induced VSMC proliferation and migration.

Animals↗
PubMedDate not supplied

Immunologic reactivity in patients with nasopharyngeal carcinoma.

Immunologic reactivity was measured in 344 patients with nasopharyngeal carcinoma (NPC), before treatment, and in 398 age-matched control subjects. The data recorded suggest that depressed cell-mediated immunity in patients with NPC is a consequence rather than a cause of the disease. In order to reduce tumor burden in patients with NPC, radiation therapy with chemotherapy or immunopotentiation or both is recommended.

Adolescent↗
PubMedDate not supplied

Multiple risk factors of nasopharyngeal carcinoma: Epstein-Barr virus, malarial infection, cigarette smoking and familial tendency.

A community-based case-control study was carried out to assess multiple risk factors and familial aggregation of nasopharyngeal carcinoma (NPC). All of the 347 pathologically-confirmed NPC new cases were serially recruited from the National Taiwan University Hospital, and healthy community controls one-to-one matched with cases on age, sex and residence were selected from household registration offices. NPC risk factors were obtained from the study subjects through standardized interviews according to a structured questionnaire. Levels of antibody to EBV-specific DNase (anti-EBV DNase) and IgA antibody to EBV viral capsid antigen (anti-EBV VCA) were determined by standard methods blindly. Multiple logistic regression analysis for matched data showed significant associations of NPC with high levels of anti-EBV DNase and anti-EBV VCA independently. The effect of cigarette smoking on NPC was modified by age. The older the age, the more striking the dose-response relation between cigarette smoking and NPC. There was no significant association between alcohol consumption and NPC. Malarial infection history was associated with NPC with an odds ratio of 2.2, but the association was significant in males only. First-degree relatives of NPC cases had a greater NPC-affected rate than those of matched healthy controls with a relative risk of 19.2, and the heritability of NPC was estimated as 0.60 (95% confidence interval = 0.55-0.64) based on the multifactorial inheritance model. Familial NPC cases were younger than sporadic cases, but environmental risk factors were similar in the two groups.

Adult↗
PubMedDate not supplied

Human leukocyte antigen (HLA) frequency among patients with nasopharyngeal carcinoma in Taiwan.

In order to assess the association between human leukocyte antigens (HLA) and nasopharyngeal carcinoma (NPC), a total of 10 familial and 10 sporadic NPC patients and 171 unrelated healthy controls were studied. HLA typing was performed using commercial trays which defined 30 specificities of HLA-A, B and C loci and 10 specificities of HLA-D locus according to the method of Tiwari and Terasaki. HLA-A2, B16 and DR1 were found to be higher among patients with NPC than unrelated healthy controls with an odds ratio (OR) and a 95% confidence interval of 5.91 (2.1-16.6), 6.00 (2.0-18.0) and 6.89 (1.3-37.5), respectively. Further analysis showed that A2(+) B16(+) haplotype was significantly associated with a much higher risk of NPC (OR = 15.5) as compared with A2(-) B16(-) haplotype. No difference in frequency distributions of HLA-A, B, C and D antigens was observed between familial and sporadic NPC patients.

Adult↗
PubMedDate not supplied

The survival of patients with nasopharyngeal carcinoma.

The survival rates following treatment of 1,555 consecutive, previously untreated patients with nasopharyngeal carcinoma were studied. A 92.5% follow-up rate in 11 years is reported. Overall survival rates were 82.7% at one year, 67.4% at two years, 47.8% at five years, and 39.8% at ten years. Computer analysis revealed various factors influencing the survivals and hence prognosis. The outcomes in this series revealed five categories; clinical staging of nasopharyngeal carcinoma in five stages is, therefore, suggested.

Adult↗