Search PubMed⌕ Search

Biomedical subjects

S F Chang

Publications and source records attributed to S F Chang.

At least 91 records · Page 5Linked to original sources
PubMed1992

Spontaneous production of growth factors for human lymphocytes from a human papillomavirus type 18-contained foreskin fibroblast cell line.

An immortalized fibroblast cell line, designated as CCFS-1/KMC, derived from human neonatal foreskin fibroblasts, contained human papillomavirus (HPV) type 18 DNA. Since this newly established cell line could spontaneously secrete activating factors for normal human blood lymphocytes, the synthesis and release of potent inflammatory cytokines from this cell line were checked. To determine the presence of cytokines in the supernatant collected from the cell line, tests by a cytokine-specific ELISA and a mitogenesis bioassay were done. The cell line could spontaneously produce several immunoreactive cytokines, such as tumor necrosis factor (TNF), interleukin 1 (IL-1) and interleukin 6 (IL-6). It also could stimulate the mitosis of human blood lymphocytes and Raji lymphoblast cell line. These cytokines were present in the same fraction of isoelectric points (pI) from 5.4 to 5.6. This study suggests that non-immune bystander cells may exert immunomodulatory effect on the immune cells via the production of potent inflammatory cytokines during viral infection.

Cell Line↗
PubMed1992

Prevalence of transposons encoding kanamycin, ampicillin and trimethoprim resistance in isolates from urinary tract infections detected using DNA probes.

Drug resistant Gram-negative bacteria causing urinary tract infections were collected. Kanamycin, ampicillin or trimethoprim-resistant strains were analyzed separately for the presence of Tn5, Tn3, or Tn7 by colony hybridization. Of these isolates, kanamycin-resistant transposons were present in 38.2% of 60 kanamycin-resistant isolates. A 3.3 kb fragment containing SacI-BamHI transposase of Tn3 and 42.6% showed a positive reaction in 129 ampicillin-resistant clinical isolates. Among the 75 trimethoprim-resistant isolates studied, 52% were shown to contain Tn7 when probed with a 1 kb BamHI fragment of Tn7. Results from Southern hybridizations demonstrated that these antibiotic resistant genes had been born on plasmids in some clinical isolates.

Ampicillin Resistance↗
PubMed1992

[Secular trends in mortality for cerebrovascular diseases in Taiwan (1959-1989)].

Cerebrovascular disease (CVD) is predominantly a disease of the elderly, and its morbidity effects increase with advancing age. In Taiwan, the increasing proportion of the elderly, as a result of medical progress and improved health care in the past 30 years, is largely responsible for the apparent increase in the number of CVD deaths. From 1963 to 1981, CVD was the leading cause of death. The crude mortality rate (CMR) and age-specific mortality rate (ASMR) of CVD by sex were derived from vital statistical data from 1959 to 1989 in Taiwan. The age-adjusted mortality rate (AAMR) using the standard world population of WHO and the cumulative mortality rate (CUMR) from birth to less than 80 years of age were calculated. Before 1983, the total number of CVD deaths had increased steadily for 30 years. In 1989, the CMR was 76.6/100,000 in men and 67.7/100,000 in women. The highest AAMR was 158.5/100,000 in 1973 for men and 130.2/100,000 in 1972 for women, and the lowest AAMR was 91.3/100,000 in 1989 for men and 81.1/100,000 in 1972 for women. The highest CUMR was 26.3% in 1968 for men and 20.8% in 1972 for women, and the lowest CUMR was 14.5% in 1989 for men and 13.6% in 1989 for women. The AAMR and CUMR for both sexes reached a maximum in 1972 and began to decline thereafter. The declines in AAMR and CUMR were averaging 2%/yr for both sexes after 1972 and were averaging 5%/yr for men and 4%/yr for women after 1983. This declining trend in CVD deaths in Taiwan began later and has been slower than similar trends in Japan and the U.S.

Aged↗
PubMed1991

Characterization of cDNA encoding the mouse hepatic triglyceride lipase and expression by in vitro translation.

A cDNA coding for the mouse hepatic triglyceride lipase has been isolated from a mouse liver cDNA library. The nucleotide sequence of the cDNA shows an open reading frame encoding a polypeptide of 510 amino acids that is 91.5% and 86% homologous to rat and human hepatic lipase, respectively. The most drastic protein sequence divergence is found at the carboxyterminal end which was speculated to harbour one heparin-binding site. By in vitro translation of cRNA in the presence of pancreatic membranes the hepatic lipase was shown to be glycosylated and to have an electrophoretic mobility of 53 kDa.

Amino Acid Sequence↗
PubMed1991

Analysis of an Escherichia coli dnaB temperature-sensitive insertion mutation and its cold-sensitive extragenic suppressor.

An Escherichia coli mutant, ts121, was isolated following random insertional mutagenesis using phage lambda Mu transposition. The mutant phenotype includes inability to form colonies at temperatures above 38 degrees C and inability to propagate phage lambda at all temperatures. A lambda i434 cI- (ts121)+ transducing phage was isolated on the basis of its ability to form plaques on ts121 mutant bacteria. Using this transducing phage, it was shown through complementation and protein analyses, that the ts121 mutation is located in the dnaB gene. The exact insertion event was identified by polymerase chain reaction amplification of the DNA sequences containing the insertion junction. The mutational insertion event in ts121 was mapped precisely between base pairs 1514 and 1515 of the dnaB gene. This result predicts that the mutant dnaB protein has lost its six terminal amino acids. The reading frame shifts into Mu-specific DNA sequences resulting in an additional 20 amino acid residues. The E. coli wild type dnaB protein participates in host replication and interacts with lambda P protein to initiate phage lambda DNA replication. Our results demonstrate that the extreme carboxyl end of the dnaB protein is required for productive interaction with the lambda P replication protein at all temperatures, and is important for dnaB function at temperatures above 38 degrees C. Cold-sensitive extragenic suppressors of the ts121 mutation were isolated on the basis of their ability to restore colony formation at 42 degrees C. One of these extragenic suppressors was mapped at 54 min on the E. coli genetic map and localized to the suhB gene, whose product may affect the expression of a number of genes at the translational level.

Bacterial Proteins↗
PubMed1991

Acetylcholine receptor-specific T-lymphocyte clones in the normal human immune repertoire: target epitopes, HLA restriction, and membrane phenotypes.

Potentially autoimmune T-lymphocyte lines specific for the nicotinic acetylcholine receptor of the neuromuscular junction have been isolated previously from patients with myasthenia gravis. We report on the isolation and expansion of T cells specific for the acetylcholine receptor of Torpedo californica or for a recombinant mammalian acetylcholine receptor alpha chain peptide (X4), from the peripheral blood of 11 healthy donors. Two major T-cell epitopes, located between amino acid positions 44-104 and 141-172, were identified using a panel of overlapping mammalian alpha chain fusion proteins. Most T lines recognized the acetylcholine receptor epitopes in the molecular context of HLA-DR molecules. Unexpectedly, all the T. californica acetylcholine receptor-specific T lines obtained from one DR4 (DRw53), DQw3 donor and two DR4, w8 (DRw53), DQw3 donors were restricted by DRw53 product(s). Using DR gene-transfected L cells as antigen presenters, in 4 lines, a close relationship between the recognized epitope and the restricting DR element was revealed. The membrane phenotype of the T. californica acetylcholine receptor-and X4-specific T lines was predominantly CD4+CD8-, with some CD4+CD8+ components. It did not significantly differ from that of control, tuberculin purified protein derivate-specific T lines raised from the same donors. These findings are in harmony with previous ones demonstrating the presence of potentially autoimmune T-lymphocyte clones within normal immune repertoires.

Antigens, CD↗
PubMed1991

Gallstones roll.

Explore the source record for details and available documents.

Cholelithiasis↗
PubMed1990

Flecainide excretion in human breast milk.

Healthy human volunteers who intended not to breast feed were placed on a regimen of 100 mg oral flecainide every 12 hours for 5 1/2 days beginning 1 day after parturition. Milk and blood samples were collected during the dosing period and for 2 days after the last dose. Concentrations of flecainide in milk and plasma were assayed by HPLC. Apparent steady-state levels of flecainide in both milk and plasma were achieved in most cases by day 4 of the study. Highest daily average concentration of flecainide in milk ranged from 270 to 1529 ng/ml for the 11 subjects. Mean +/- SD milk to plasma flecainide ratios were 3.7 +/- 3.5, 3.2 +/- 2.3, 3.5 +/- 2.1, and 2.6 +/- 0.7 on study days 2, 3, 4, and 5, respectively. After the last dose of flecainide, peak milk levels of the drug occurred at 3 to 6 hours and then declined monoexponentially. The half-life for elimination of flecainide from milk was 14.7 +/- 3.5 hours and is very similar to the plasma elimination half-life of flecainide in healthy human subjects. The mean milk to plasma ratios for flecainide after the last dose were 2.3 +/- 1.0 and 2.9 +/- 1.1 at 24 and 48 hours after the dose, respectively. Based on the pharmacokinetics of flecainide in infants, the expected average steady-state plasma concentration of flecainide in a newborn infant consuming all of the milk production of its mother (approximately 700 ml/day) would not be expected to exceed about 62 ng/ml.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1990

Growth and characterization of normal human keratinocytes in F12 serum-free medium.

In a F12 medium supplemented with epidermal growth factor (20 ng/ml), insulin (5 micrograms/ml), transferrin (5 micrograms/ml), hydrocortisone (1 microM), cholera toxin (40 ng/ml), endothelial cell growth supplement (15 ng/ml) and retinoic acid (1 x 10(-7) M) on Vitrogen coated culture dishes, normal adult and newborn human foreskin keratinocytes were cultured for 4- and 2-time with population doublings (PD) accumulated as 8 and 12, respectively. The cells grown in this medium possessed a basaloid, undifferentiated and hyperproliferating nature, with a population doubling time of about 24 hours at early passage. Between the 1st and 2nd subcultures, cell proliferation was the most active. Delaying the time of first subculture lowered the rate of cell proliferation. The keratin of the cultured cells was studied by immunoblotting and revealed the presence of permanent keratin markers of the human skin (AE1 50 kDa and AE3 58kDa) as well as a relatively high intensity of a proliferating marker (AE1 48 kDa) and a relatively low intensity of a differentiation marker (AE3 67 kDa).

Adult↗
PubMed1989

Preparation and characterization of monoclonal antibody specific for alpha-bungarotoxin and localization of the epitope.

We prepared a monoclonal antibody (mAb) specific for alpha-bungarotoxin (alpha-BuTX) which can neutralize the lethal toxicity of the toxin and inhibit the binding of [3H]-alpha-BuTX to the nicotinic acetylcholine receptor. The radiolabelled toxin has a high affinity for the mAb. alpha-BuTX was digested with acid protease A and the resulting peptide fragments were isolated by reverse-phase HPLC. The epitope recognized by the mAb has been localized on the basis of competition radioimmunoassay between [3H]-alpha-BuTX and the peptide fragments of alpha-BuTX towards the antibody. The epitope specific for the mAb may be located in the second loop of alpha-BuTX, probably involving residues 34-41.

Amino Acid Sequence↗
PubMed1989

In vivo and in vitro studies on the release of thyrotropin in aging rats.

Effects of aging on the concentration of serum thyrotropin (TSH) and the release of TSH in vitro from anterior pituitary glands (APs) of male and female rats were investigated. Rats with 3-5 (young) and 24-26 (old) months of age were used. Some female rats were ovariectomized (Ovx) 10 weeks before use. After decapitation, trunk blood was collected. APs were bisected and preincubated with Krebs-Ringer phosphate buffer (KRB) at 37 degrees C for 60 min. They were then incubated with or without 10 nM thyrotropin-releasing hormone (TRH) for 30 min. The media were collected and replaced by fresh KRB. Incubations were continued and KRB media were changed three times, once every 30 min. One hemi-AP per flask and 7 or 8 flasks per group were used. The concentration of TSH in the medium and serum samples was measured by radioimmunoassay. The level of serum TSH in the diestrous, estrous and Ovx rats was reduced by aging. Thirty min after incubation with TRH, the release of TSH from APs of old intact female or Ovx rats was significantly (P less than 0.01) less than that of corresponding young rats. The concentration of serum TSH and TRH-stimulated release of TSH from APs of male rats was not altered by aging. There was no difference in the basal release of TSH from APs between old and young animals. These data suggest that the release of TSH from APs in response to TRH is decreased by aging in female but not in male rats.

Aging↗
PubMed1989

The subtypes, distribution and location of human papillomavirus DNA in genital warts and genital Bowen's disease--a study using in situ DNA.DNA hybridization.

The aim of this study is to investigate the difference in subtypes and distribution of human papillomavirus (HPV) between the benign pathological condition- Genital wart (condyloma acuminatum, verruca- like lesion and papular lesion) and genital Bowen's disease (Bowenoid papulosis, Mollucum contagiosum with Bowenoid papulosis and Condyloma acuminatum with verruca- like lesion and pathological bowenoid change) of genitalia by in situ DNA.DNA hybridization. In situ DNA.DNA hybridization was performed by hybridizing the RNAse treated and denatured frozen skin section with 3H-labeled HPV 6, 11, 16 and 18-DNAs probes and then developed autoradiogram on a glass slide. The results reveal that: (1) The benign cases are strongly associated with HPV 6/11, while the bowenoid cases are associated with HPV 16/18, indicating 16 positive in 24 cases and 3 positive in 5 cases respectively; (2) Four of sixteen benign cases were doubly infected with HPV 6/11 and 16/18; and 2 of 2 bowenoid cases were infected with HPV 16/18 only (3) In benign cases, HPV distributes through the upper third of epidermis and in bowenoid cases, HPV scatters throughout the whole epidermis including parabasal layers. These findings may indicate that the subtypes of HPV, the interaction of weak oncogenic virus (HPV 6/11) and strong oncogenic virus (HPV 16/18) and the presence of HPV on proliferating cells (parabasal layers) all play a part in oncogenicity. The detectability of HPV 6/11 DNA in both the nucleus and cytoplasm indicate that: 1). In situ DNA.DNA hybridization is a more sensitive method than the immunological detection of capsid antigen. 2). In addition to the nucleus, the cytoplasm is a site through which HPV 6/11 virus should pass during their life cycle. Using PEG hybridization mixture, it was revealed that 6 of the 6 HPV 6/11 positive condyloma acuminata harbored HPV 6. This result indicates that the subtype of HPV determine the gross morphology of skin lesion.

Bowen's Disease↗
PubMed1989

Characterization of cytotoxicity and R-plasmid in Salmonella krefeld.

From 1981 to 1984, 254 isolates of Salmonella krefeld were isolated from newborns and infants with acute gastroenteritis in southern Taiwan. All the crude enterotoxin preparations of S. krefeld caused the cytotoxic elongation reaction in Chinese hamster ovary K1 (CHO-K1) cells. Cytotoxic enterotoxin was also produced by S. krefeld inducing Vero cells to round up and appear partially detached from the culture plate. It was noted that S. krefeld showed internalization and multiplication in CHO-K1 cells. S. krefeld exhibited 12 different resistant patterns. And the predominant patterns were found to be resistant to kanamycin and ampicillin (Ka-Amr), and resistant to kanamycin, ampicillin, chloramphenicol and tetracycline (Ka-Am-Cm-Ter). It was found that two distinct plasmids of 34 megadalton (Md) and 120 Md were commonly present in these strains. S. krefeld haboured 34 Md and 120 Md R-plasmid, which conferred resistance to Ka-Amr and Ka-Am-Cm-Ter, respectively. From the resistance transferred patterns, Ka-Amr was the most common resistance among transconjugants. The frequency of transfer of the 34 Md R-plasmid (2.71 x 10(-3) transconjugants/donor cell) from S. krefeld to E. coli K-12 14R525 was 20 times higher than that of the 120 Md R-plasmid (1.48 x 10(-4) transconjugants/donor cell). In analysis of the restriction endonuclease digest of the 34 Md plasmid obtained from different bacterial sources, their specific identical DNA fragment pattern suggested that the outbreak infection due to S. krefeld had a common origin.

Cell Line↗
PubMed1989

Factor analysis for the presence of serum HBV DNA in chronic hepatitis B virus infection.

To elucidate the role of HBeAg and other influential factors for the presence of serum HBV DNA and their interactions, serum HBV DNA was examined in 68 patients with chronic HBV infections and 23 HBsAg negative persons by molecular hybridization. Based on the univariate analysis, the positive rate of HBV DNA was higher in patients with HBeAg (31/43, 72.1%) than in patients with anti-HBe (5/22, 22.7%) with an odd ratio of 8.78. The positive rates of HBV DNA between men and women were not significantly different, and the positive rates of HBV DNA were not related to the SGPT levels. The mean age of patients without HBV DNA was higher than that of patients with HBV DNA (p value less than 0.025), and the positive rate and concentration of HBV DNA were decreased with increasing age (p value less than 0.005). The positive rates of serum HBV DNA among different histological changes were not statistically different. However, the discordance of HBV DNA and HBeAg/anti-HBe was increased when the liver parenchymal damage became severe (p less than 0.05). Only 5 patients were anti-D positive and 3 of them had serum HBV DNA. To exclude interactions of the influential factors, multivariate analysis was also performed. HBeAg was the only significant factor for the presence of serum HBV DNA when logistic regression was used (p less than 0.001). The age was an important factor when the concentration of serum HBV DNA was considered.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1988

Pharmacokinetics and bioavailability of hydromorphone: effect of various routes of administration.

The pharmacokinetics and bioavailability of hydromorphone following various routes of administration, i.e., intravenous, oral, intranasal, and transdermal, were investigated in rabbits. Hydromorphone plasma concentrations were determined by reverse-phase high-performance liquid chromatography (HPLC). Comparison of area under the concentration versus time curve (AUC) between intravenous and oral administrations showed a low bioavailability of hydromorphone after oral administration. The nasal absorption of hydromorphone was studied by the in situ nasal recirculation technique, and the results showed that hydromorphone is well absorbed from the nasal mucosa. The transdermal permeation of hydromorphone was also evaluated for 24 hr and a steady-state plasma concentration (0.135 micrograms/ml) was achieved during the 6- to 24-hr periods following the application of a transdermal patch on the inner pinna of the rabbit's ear.

Administration, Cutaneous↗