Biomedical subjects
T C Lin
Publications and source records attributed to T C Lin.
Cloning, nucleotide sequence, and overexpression of the bacteriophage T4 regA gene.
The bacteriophage T4 regA gene codes for a regulatory protein that controls the expression of a number of T4 early genes, apparently at the level of translation. Restriction fragments containing the regA structural gene have been cloned into phage M13, and the nucleotide sequence has been determined. Translation of the DNA sequence predicted that regA protein contains 122 amino acids, with a Mr of 14,620. A DNA fragment carrying 85% of the coding sequence of regA has been cloned into the phage lambda leftward promoter PL expression vector pAS1, and a high level of truncated regA protein was produced by nalidixic acid induction. Protein chemical studies of the truncated regA protein gave results consistent with the nucleotide sequence of the regA gene. Subsequently, an intact regA gene was cloned into plasmid pAS1 and overexpressed. The regA protein produced in this way regulates the level of T4 45 and 44 proteins when their corresponding genes are carried on the same plasmid as the regA gene.
Study of subretinal intercellular space.
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Structure of the filamentous bacteriophage fl. Location of the A, C, and D minor coat proteins.
The location within the virion of the A, C, and D minor coat proteins of the filamentous bacteriophage fl has been analyzed. The A protein is present in approximately 5 copies/particle and is located at the tip of normal length phage, miniphage, and fl/pBR322 chimeric phage, a longer than normal length phage. The mole ratios of the A, C, and D proteins are the same for each type of particle, consistent with a model of phage organization in which the minor coat proteins are clustered near or at the ends of the phage. Normal length phage were fragmented by passing them through a French press, and those fragments that contained the A protein were separated from those that did not by treating the mixture with anti-A protein antibody. Analysis of the protein compositions of the two populations of fragments showed that the A and D proteins were found together in one population of fragments and that most, it not all, of the C protein was found in the other. These results show that the D protein is located near or at the A protein end of the phage and that the C protein is located in a region near or at the opposite end. Treatment of the virion with proteases which lowered the infectivity of the phage resulted in particles in which only the A protein was cleaved to any detectable extent. These particles remained resistant to the action of micrococcal nuclease.
Structure of filamentous bacteriophage: isolation, characterization, and localization of the minor coat proteins and orientation of the DNA.
The minor coat proteins of the filamentous bacteriophage fl and fd have been isolated and characterized. The phage have approximately 5 copies each of the A protein (product of gene III) and the D protein (product of gene VI). The phage also contains about 10 copies of the C protein. Preliminary evidence suggests that the "C protein" may actually be a mixture of proteins, the major component of which is the product of gene IX. The D protein is located near or at the A protein end of the phage, and the C protein is located in a region near or at the other end. The DNA appears to be oriented iun the virion such that the DNA which specifies the intergenic region is located close to the C protein end of the phage and that which codes for the gene III protein is located near the A and D protein end.
Isolation and characterization of the C and D proteins coded by gene IX and gene VI in the filamentous bacteriophage fl and fd.
The C and D proteins from bacteriophage fd and fl have been purified and characterized. Since the DNA sequence is known, the amino acid composition of these purified proteins indicated that they are coded for by the phage, the C protein being the product of Gene IX and the D protein specified by Gene VI. The molecular weights of the C and D proteins were calculated from the DNA sequences to be 3,650 and 12,350, respectively. These values are close to the molecular weights observed after polyacrylamide gel electrophoresis of the proteins in sodium dodecyl sulfate. Since the C and D proteins can be selectively labeled with radioactive cysteine and arginine, it was possible to estimate the number of the C and D protein molecules relative to the number of A protein molecules which had been accurately determined in previous studies. Based on these results, the average phage particle contains 5 A, 5 D, and 10 C protein molecules.
The A protein of bacteriophage fd: its interference with viral infection.
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[Virus multiplication in pigs inoculated with lapinized hog cholera live vaccine].
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Evaluation of the fluorescent antibody--cell culture test for detection and titration of hog cholera virus.
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Pathogenesis of hog cholera virus infection in experimentally inoculated swine.
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[Observation on the geriatric patients. Comprehensive study of 1,695 in-patients over 61-years-old in the department of internal medicine, N.T.U.H., between 1956-1962].
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Atrial tachyarrhythmias induced by acetylcholine in tilapia (Oreochromis sp.) isolated atria.
1. Effects of the parasympathetic neuromediator acetylcholine (ACh) on atrial tissues vary greatly depending on the species, the type of atrial cells and experimental conditions. The aim of the present study was to investigate, with microelectrode techniques, the arrhythmogenic effects of ACh in tilapia (Oreochromis sp.) isolated atria at room (22-25 degrees C) and high temperature (37 degrees C). 2. Acetylcholine (1-10 micromol/L) shortened action potential duration (APD), depressed action potential plateau and decreased twitch force in tilapia atria, as it did in human atrial fibres. In addition, ACh induced premature responses and re-entrant tachyarrhythmias (TA; frequency range from 7 to 25 Hz) in five of 19 and 14 of 22 tilapia atria tested at room and high temperature, respectively. The higher incidence of ACh-induced TA at 37 degrees C compared with room temperature was statistically significant. 3. The ACh-induced TA consisted of high-frequency and uniform action potentials accompanied by tension oscillation and elevation of diastolic force (flutter). Acetylcholine-induced TA could be readily abolished by atropine (1 micromol/L) and prevented by treatment with agents with local anaesthetic properties, such as 0.1 micromol/L tetrodotoxin or 3 micromol/L quinidine. The antagonistic action of quinidine occurred without significant prolongation of APD. 4. The present findings suggest that pharmacological concentrations of the cholinergic muscarinic agonist ACh readily induce TA (mainly atrial flutter) in tilapia atria, presumably via sodium channel-dependent re-entrant excitation. The poikilothermic tilapia appears to be an appropriate animal model for the study of atrial TA.
Factors predictive of survival in patients with node-positive colorectal cancer in Taiwan.
BACKGROUND/AIMS: Preoperative CEA levels, depth of tumor penetration, and the number of positive lymph nodes were reported as independent factors prognostic of survival in colorectal cancer patients. This study was carried out in an effort to evaluate the prognostic significance of these three factors in patients with Dukes' C colorectal cancer in Taiwan. METHODOLOGY: Between 1992 and 1994, a total of 112 patients with node-positive colorectal cancer were evaluated retrospectively at the Veteran General Hospital-Taipei. All patients underwent potentially curative surgery and received 5-fluorouracil based adjuvant chemotherapy. Reference to the Dukes' classification was according to the classical criteria described in 1932 for carcinoma of the rectum and adapted for use in colonic tumors. Data on the location of the tumor, depth of penetration, number of positive lymph nodes, degree of tumor differentiation, and preoperative CEA levels were analyzed to understand their association with survival. Blood samples for CEA measurement were taken a few days before operation. A multivariate analysis using the Cox's proportional hazards regression model was then performed to determine the most important independent predictors of survival among all the possible variables. RESULTS: Using univariate analysis the number of positive lymph nodes (P < 0.001), penetration of the bowel wall (P < 0.001), and preoperative CEA levels (P < 0.001) were found as significant prognostic factors, while the degree of tumor differentiation, location of the tumor, age and sex were not significant. Using multivariate Cox analysis the number of positive lymph nodes, penetration of the bowel wall, and preoperative CEA levels were still found as independent prognostic factors in node-positive colorectal cancer patients. CONCLUSIONS: Data obtained from our study indicates that preoperative CEA levels, depth of tumor penetration, and the number of positive lymph nodes were independent prognostic factors in Dukes' C colorectal cancer patients. They could serve as appropriate modifications of the initial Dukes scheme in node-positive diseases.
Randomized trial comparing weekly bolus 5-fluorouracil plus leucovorin versus monthly 5-day 5-fluorouracil plus leucovorin in metastatic colorectal cancer.
BACKGROUND/AIMS: The purpose of this study was to compare the efficacy and toxicity profiles of weekly intravenous (i.v.) bolus injection of 5-fluorouracil plus low-dose leucovorin with the Mayo Clinics' monthly 5-day schedule of 5-fluorouracil and leucovorin in the treatment of metastatic colorectal cancer. METHODOLOGY: A total of 96 patients with previously untreated metastatic colorectal cancer were randomized to receive either a weekly i.v. bolus injection of 5-fluorouracil 400 mg/m2 plus leucovorin 20 mg/m2 (weekly arm), or i.v. bolus injection of 5-fluorouracil 425 mg/m2 plus leucovorin 20 mg/m2 for 5 consecutive days every 4 or 5 weeks (monthly arm). Therapy was continued until disease progression or unacceptable toxicity appeared. In the presence of disease progression, the study regimen was stopped and second-line treatment was instituted after the patient was discontinued from this study. RESULTS: There was no significant difference of response rates between both regimens. The response rate were 14.3% in the weekly arm (2 CR and 5 PR, 95% CI: 2.6-25.2%) and 10.6% in the monthly arm (1 CR and 4 PR; 95% CI: 6.5-32.3%), respectively (P = 0.8957). The survival times were also similar between the two (P = 0.4207, log-rank test). The median survival were 15.8 months in the monthly arm and 18.4 months in the weekly arm. Hematologic toxicity was minimal in both arms. However, the monthly arm produced a higher toxicity in severe (grade 3-4) diarrhea (14.9% vs. 2%; P = 0.029) and stomatitis (8.5% vs. 0; P = 0.054). CONCLUSIONS: Weekly bolus injection of 5-fluorouracil and low-dose leucovorin achieved a similar response rate and survival as compared with the Mayo Clinics' monthly 5-day schedule, but severe toxicity was less commonly seen using the weekly regimen. As current chemotherapeutic treatment for metastatic colorectal cancer is largely palliative rather than curative, the weekly bolus regimen may be a more favorable approach in managing metastatic colorectal cancer.
Antioxidant and free radical scavenging effects of the tannins of Terminalia catappa L.
Reactive oxygen species (ROS) react with biological molecules and destroy the structure of cells and eventually cause free radical-induced disease such as inflammation and cancer. Previous studies showed that an aqueus extract of Terminalia catappa L. exhibited superoxide radical scavenger activity and modification of mitomycin C-induced clasto-genicity. In order to investigate the multiple antioxidant effect of the tannin components of T. catappa L., their ability to prevent lipid peroxidation, superoxide formation and their free radical scavenging activity were evaluated. The results indicated that all of these components showed potent antioxidant activity. Punicalagin and punicalin were the most abundant components and had the strongest anti-oxidative effects of this group of tannins.
A brief report on the production of primary specific-pathogen free pigs by hysterectomy in Taiwan, Republic of China.
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