Search PubMed⌕ Search

Biomedical subjects

C Y Lee

Publications and source records attributed to C Y Lee.

At least 55 records · Page 3Linked to original sources
PubMed2001

Clinical application of computer-aided rapid prototyping for tooth transplantation.

The maintenance of healthy periodontal ligament cells in the donor tooth is one of the most important factors for successful tooth transplantation. This is achieved by minimizing the extraoral time during the surgical procedure. If a duplicate form of donor tooth could be obtained before extraction, it would be possible to precontour the recipient alveolar bone compatible with the donor tooth, and thereby reduce the extra-oral time of the donor tooth. We obtained a three-dimensional image with the real dimensions of the donor tooth from a CT Highspeed Advantage, allowing a life-sized resin model of the tooth to be fabricated. From 22 clinical cases, we achieved an average total transplantation time of 7.7 min. The average distance between the transplanted root surface and the alveolar bone from 12 available cases was 0.87 mm at the mesial cervix, 0.91 mm at the mesial apex, 0.98 mm at the distal cervix and 1.16 mm at the distal apex on the postoperative radiographs. Clinical data indicate that computer-aided rapid prototyping may be of value in minimizing the extra-oral time and possible injury to transplanted tooth during the process of autotransplantation.

Adult↗
PubMed2001

Formation of protoberberine-type alkaloids by the tubers of somatic embryo-derived plants of Corydalis yanhusuo.

The effects of 0.5 - 5 mg/l abscisic acid [ABA], 0.5 - 10 mg/l (2RS,3RS)-1-(4-chlorophenyl)-4,4-dimethyl-2-(1,2,4-triazol-1-yl)pentan-3-ol [paclobutrazol] and 0.5 - 2 mg/l alpha-cyclopropyl-alpha-(4-methoxyphenyl)-5-pyrimidinemethanol [ancymidol], 0.5 - 5 mg/l gibberellic acid [GA(3)] and 15 - 100 mg/l polyethylene glycol [PEG] 4000 supplemented in half-strength Murashige and Skoog's (MS) medium on the production of the two major protoberberine-type alkaloids (D,L-tetrahydropalmatine and D-corydaline) by the tubers of somatic embryo-derived plants of Corydalis yanhusuo were examined. Somatic embryo derived plants were also maintained for 6 months on half-strength MS medium containing 0.1 mg/l GA(3) or 0.5 mg/l paclobutrazol. The alkaloid contents were determined by high performance liquid chromatography (HPLC). The analysis revealed that the contents of D,L-tetrahydropalmatine and D-corydaline in the tubers of somatic embryo-derived plants were higher than the marketed crude drug and varied with growth regulator/PEG-4000 treatment and the age of the plant.

Abscisic Acid↗
PubMed2001

Identification of oral spirochetes at the species level and their association with other bacteria in endodontic infections.

OBJECTIVES: Recent molecular approaches have revealed that fastidious organisms such as Bacteroides forsythus and oral treponemes were frequently found in root canals with apical periodontitis. The purpose of this study was to identify the isolates of oral spirochetes at the species level in endodontic infections and to determine their association with B forsythus and Porphyromonas gingivalis. STUDY DESIGN: Seventy-nine teeth with apical periodontitis were selected for this study. After sampling from the root canals aseptically, polymerase chain reaction amplification for the 16S rRNA gene was performed with eubacterial universal primers. Subsequently, dot-blot hybridization was performed with 8 species-specific oligonucleotide probes. The microbial associations were analyzed by using the odds ratio. RESULTS: The most frequently found species was P gingivalis (27.4%), followed by Treponema maltophilum (26%), B forsythus (16.4%), and Treponema socranskii (2.7%). Other treponemes, including Treponema denticola, were not detected in our samples. Significant microbial associations were identified between T maltophilum, B forsythus, and P gingivalis by performing analysis with the odds ratio. CONCLUSION: Our results indicate that T maltophilum should be included in etiologic studies of endodontic diseases.

Adolescent↗
PubMed2001

Multi-step sequential batch two-phase anaerobic composting of food waste.

This study was conducted to evaluate the newly devised process, called MUlti-step Sequential batch Two-phase Anaerobic Composting (MUSTAC). The MUSTAC process consisted of several leaching beds for hydrolysis, acidification and post-treatment, and a UASB reactor for methane recovery. This process to treat food waste was developed with a high-rate anaerobic composting technique based on the rate-limiting step approach. Rumen microorganisms were inoculated to improve the low efficiency of acidogenic fermentation. Both two-phase anaerobic digestion and sequential batch operation were used to control environmental constraints in anaerobic degradation. The MUSTAC process demonstrated excellent performance as it resulted in a large reduction in volatile solids (VS) (84.7%) and high methane conversion efficiency (84.4%) at high organic loading rates (10.8 kg VS m(-3) d(-1)) in a short SRT (10 days). Methane yield was 0.27 m3 kg(-1) VS, while methane gas production rate was 2.27 m3 m(-3) d(-1). The output from the post-treatment could be used as a soil amendment, which was produced at the same acidogenic fermenter without troublesome moving. The main advantages of the MUSTAC process were simple operation and high efficiency. The MUSTAC process proved stable, reliable and effective in resource recovery as well as waste stabilization.

Animals↗
PubMed2001

Gliotoxin induces apoptosis in cultured macrophages via production of reactive oxygen species and cytochrome c release without mitochondrial depolarization.

The cytotoxicity and its underlying mechanisms induced by gliotoxin (GT), an immunosuppressive agent, in macrophages are poorly understood. We report here that GT induced a rapid apoptosis (DNA fragmentation and hypodiploid nuclei obtained within 4 hrs of treatment) in murine macrophages PU5-1.8 in a dose-dependent and cell cycle-independent manner. The GT-induced apoptosis was suppressed by z-Asp, z-VAD-fmk and antioxidants suggesting that production of reactive oxygen species (ROS) and activation of caspases were important in this process. Also, release of cytochrome c from mitochondria was found to be an early event (within 1 hr) after addition of GT (250 ng/ml) and its presence in the cytosol was sufficient to elicit apoptosis. Interestingly, the release of cytochrome c was not accompanied by a reduction in the mitochondrial membrane potential (psi m) as determined by several psi m-sensitive fluorescent indicators. Taken together, our results indicate that GT is a potent apoptotic agent in PU5-1.8 cells and the loss of psi m is not a universal early marker for apoptosis.

Animals↗
PubMed2001

Kinetic analysis of inhibitory substrate degradation in bioaugmented activated sludge process.

A steady-state model coupling Haldane kinetics and mass conservative principles was developed herein to depict the degradation of a single inhibitory substrate in a bioaugmented activated sludge reactor. The substrate toxicity impact on the bioaugmentation was evaluated for three levels of inhibition coefficient Ki: 0.1, 10, and 1000 mg/L. Under high toxicity conditions of Ki = 0.1 mg/L, the input biomass markedly enhanced the substrate removal. However, at less toxicity of Ki > 10 mg/L, the input biomass was ineffective. The sensitivity study confirmed the parameters of k, Ks, and bd has no connection with Ki, but depends on the amounts of degradative bacteria inside the reactor. Alternatively, parameter Y is important only when Ki is greater than 10 mg/L and the bacteria significantly utilize the substrate. In addition, a novel indicator of marginal solids retention time examines the economic advantages of adding biomass as compared to extending the solids retention time.

Bacteria↗
PubMed2001

Steroid regulation of autophagic programmed cell death during development.

Apoptosis and autophagy are morphologically distinct forms of programmed cell death. While autophagy occurs during the development of diverse organisms and has been implicated in tumorigenesis, little is known about the molecular mechanisms that regulate this type of cell death. Here we show that steroid-activated programmed cell death of Drosophila salivary glands occurs by autophagy. Expression of p35 prevents DNA fragmentation and partially inhibits changes in the cytosol and plasma membranes of dying salivary glands, suggesting that caspases are involved in autophagy. The steroid-regulated BR-C, E74A and E93 genes are required for salivary gland cell death. BR-C and E74A mutant salivary glands exhibit vacuole and plasma membrane breakdown, but E93 mutant salivary glands fail to exhibit these changes, indicating that E93 regulates early autophagic events. Expression of E93 in embryos is sufficient to induce cell death with many characteristics of apoptosis, but requires the H99 genetic interval that contains the rpr, hid and grim proapoptotic genes to induce nuclear changes diagnostic of apoptosis. In contrast, E93 expression is sufficient to induce the removal of cells by phagocytes in the absence of the H99 genes. These studies indicate that apoptosis and autophagy utilize some common regulatory mechanisms.

Animals↗
PubMed2001

Quaternized wood as sorbent for hexavalent chromium.

The potential of quaternized wood (QW) chips in removing hexavalent chromium from synthetic solution and chrome waste under both batch and continuous-flow conditions was investigated. Sorption was found to be dependent on pH, metal concentration, and temperature. QW chips provide higher sorption capacity and wider pH range compared with untreated wood chips. The equilibrium data could be fitted into the Langmuir isotherm model, and maximum sorption capacities were calculated to be 27.03 and 25.77 mg/g in synthetic chromate solution and chrome waste, respectively. The presence of sulfate in high concentration appeared to suppress the uptake of chromium by QW chips. Column studies showed that bed depth influenced the breakthrough time greatly whereas flow rate of influent had little effect on its sorption on the column.

Adsorption↗
PubMed2001

Molecular cloning of the porcine acid-labile subunit (ALS) of the insulin-like growth factor-binding protein complex and detection of ALS gene expression in hepatic and non-hepatic tissues.

The acid-labile subunit (ALS) is an approximately 85 kDa N-glycoprotein that is known primarily as a component of the systemic insulin-like growth factor-binding protein (IGFBP) complex. We have amplified, using a PCR, three overlapping porcine ALS genomic DNA fragments that together encode the distal region of the signal peptide through to the COOH-terminus. The compiled sequence of 1775 nucleotides of the three overlapping DNAs and the deduced amino acid sequence of the mature porcine ALS (pALS) protein exhibited 84/81%, 79/77%, 79/78% and 84/79% identities with respect to those of the human, the rat, the mouse and the baboon respectively. Four conserved cysteine residues in the NH(2)-terminal domain and 20 leucine-rich repeats in the central domain also were identified at identical positions in the porcine ALS. By using Northern blot analysis, with a genomic DNA fragment as the probe, it was determined that a 2.2 kb ALS mRNA was induced in the liver during the late fetal stage, and hepatic ALS mRNA abundance was increased post-natally. Moreover, hepatic ALS mRNA abundance was increased by daily injection of porcine somatotropin (100 microg/kg body weight) in cross-bred market pigs each weighing approximately 100 kg. The ALS mRNA was not detected by Northern analysis in any non-hepatic tissue examined. However, results of a more sensitive solution hybridization/RNAse protection assay indicated that low levels of ALS mRNA were also present in adult muscle, spleen, ovary and uterus, but not in lung, kidney, oviduct and placenta. Taken together, the present results suggest that although liver is the primary organ that expresses the ALS gene under somatotropin stimulation, some non-hepatic tissues also express the gene at low levels in the pig.

Amino Acid Sequence↗
PubMed2001

A single center's 30 years' experience of esophageal adenocarcinoma.

BACKGROUND: Adenocarcinoma of the esophagus has been reported to be increasing in incidence in a number of regions throughout the world, while the incidence of squamous cell carcinoma (SCCA) of the esophagus is mostly stable or decreasing. To evaluate the increasing tendency of adenocarcinoma of the esophagus. METHODS: We studied retrospectively the records of patients with histologically proven esophageal cancer between 1970 and 1999 at the Yonsei Medical Center. RESULTS: Total cases of esophageal cancer were 969 patients of which the cases of adenocarcinoma and SCCA were 27 patients and 918 patients, respectively. The ratio of esophageal adenocarcinoma to SCCA was 0.0375 in the 1970s, 0.0241 in the 1980s and 0.0292 in the 1990s. There was no statistical difference (p = 0.811) in the ratios of adenocarcinoma of the esophagus between the three consecutive 10-year groups. CONCLUSION: In conclusion, unlike the US and other western countries, it seems that the ratio of esophageal adenocarcinoma compared to SCCA has not increased among patients with esophageal carcinoma at the Yonsei Medical Center.

Adenocarcinoma↗
PubMed2001

Protein-protein interaction of FHL3 with FHL2 and visualization of their interaction by green fluorescent proteins (GFP) two-fusion fluorescence resonance energy transfer (FRET).

LIM domain proteins are found to be important regulators in cell growth, cell fate determination, cell differentiation and remodeling of the cell cytoskeleton. Human Four-and-a-half LIM-only protein 3 (FHL3) is a type of LIM-only protein that contains four tandemly repeated LIM motifs with an N-terminal single zinc finger (half LIM motif). FHL3 expresses predominantly in human skeletal muscle. In this report, FHL3 was shown to be a novel interacting partner of FHL2 using the yeast two-hybrid assay. Furthermore, site-directed mutagenesis of FHL3 indicated that the LIM2 of FHL3 is the essential LIM domain for interaction with FHL2. Green fluorescent protein (GFP) was used to tag FHL3 in order to study its distribution during myogenesis. Our result shows that FHL3 was localized in the focal adhesions and nucleus of the cells. FHL3 mainly stayed in the focal adhesion during myogenesis. Moreover, using site-directed mutagenesis, the LIM1 of FHL3 was identified as an essential LIM domain for its subcellular localization. Mutants of GFP have given rise to a novel technique, two-fusion fluorescence resonance energy transfer (FRET), in the determination of protein-protein interaction at particular subcellular locations of eukaryotic cells. To determine whether FHL2 and FHL3 can interact with one another and to locate the site of this interaction in a single intact mammalian cell, we fused FHL2 and FHL3 to different mutants of GFP and studied their interactions using FRET. BFP/GFP fusion constructs were cotransfected into muscle myoblast C2C12 to verify the colocalization and subcellular localization of FRET. We found that FHL2 and FHL3 were colocalized in the mitochondria of the C2C12 cells and FRET was observed by using an epi-fluorescent microscope equipped with an FRET specific filter set.

Base Sequence↗
PubMed2001

Cellular cholesterol efflux is modulated by phospholipid-derived signaling molecules in familial HDL deficiency/Tangier disease fibroblasts.

Familial HDL deficiency (FHD) is the heterozygous form of Tangier disease (TD). Mutations of the ABCA1 gene cause FHD and TD. FHD/TD cells are unable to normally efflux cholesterol onto nascent HDL particles, which are rapidly catabolized. TD fibroblasts have an abnormal pattern of PLC and PLD activation following cell stimulation with HDL(3) or apolipoprotein A-I (apoA-I). We examined cellular cholesterol efflux in FHD and TD fibroblasts by phospholipid-derived-molecules, compared with that of normal cells. We used the PKC agonist 1,2-dioctanoylglycerol (DOG) and phorbol myristate acetate (PMA) to activate PKC, calphostin C, and GO 6976, as inhibitors of PKC; phosphatidic acid (PA), which is the product of PLD, and lysophosphatidic acid (LPA), phosphatidylcholine, sphingomyelin, and beta-cyclodextrin to investigate their potential effect in modulating cellular cholesterol efflux in [(3)H]cholesterol-labeled and cholesterol-loaded fibroblasts. Phosphatidylcholine, sphingomyelin, and beta-cyclodextrin promoted cholesterol efflux in an identical fashion in control, FHD, or TD fibroblasts. In a dose-dependent fashion, DOG (0-200 microM) increased apoA-I-mediated cellular cholesterol efflux by 40% in controls, 71% in FHD, and 242% in TD cells. PMA similarly increased cholesterol efflux to a maximum of 256% in controls, 182% in FHD, and 191% in TD cells. This effect was inhibited by calphostin C. PA (100 microM) also increased cholesterol efflux by 25% in control, 44% in FHD, and 100% in TD cells. Conversely, LPA reduced cholesterol efflux in a dose-dependent fashion in control and FHD cells (-50%, 200 microM) but not in TD cells, where efflux was increased by 140%. Propranolol (100 microM) significantly increased cholesterol efflux at 24 h in all three cell lines. n-Butanol partially decreased the DOG-mediated increase in cholesterol efflux. The inhibitory effect of calphostin C on DOG-stimulated cholesterol efflux could be partially overcome by propranolol, suggesting that PA is a downstream mediator of PKC-stimulated cholesterol efflux. We conclude that PLC and PLD activities are required for apoA-I-mediated cellular cholesterol efflux, and modulating cellular PA concentration can correct, at least partially, the cholesterol efflux defect in FHD and TD.

Adult↗
PubMed2001

Immunogenicity and fecal poliovirus excretion in sequential use of inactivated and oral poliovirus vaccines.

BACKGROUND AND PURPOSE: Though inoculation with inactivated poliovirus vaccine (IPV) is advocated, sequential use of IPV and live oral poliovirus vaccines (OPV) has many advantages. This study aimed to define the immunogenicities of IPV and OPV in Taiwanese children after the use of a sequential schedule of IPV-OPV and also to determine whether prior IPV inoculation hampers the fecal passage of OPV. METHODS: Fifty-nine infants were recruited to receive IPV-OPV sequential vaccinations consisting of IPV given at the ages of 2 and 4 months and OPV given at the ages of 6 and 18 months. Blood samples were taken at ages 2, 6, 18, and 19 months for antibody determination, and stool samples were collected to isolate vaccine strains of poliovirus after the second dose of OPV, at the age of 18 months. RESULTS: None of the children had severe systemic or local reactions. Protective antibodies were detected in all infants at the age of 6 months, 2 months after the second IPV dose. The antibody titers were augmented at the age of 19 months, 1 month after the booster dose of OPV. Stool samples collected 7 days after the second dose of OPV yielded at least one type of poliovirus in 9 of 18 children. Analysis of stool samples revealed that poliovirus was excreted by the 28th day in only two of the children. CONCLUSIONS: Our study showed that both IPV and OPV exhibit immunogenicity in Taiwanese children. Side effects of an IPV-OPV sequential schedule were mild and infrequent. Viral shedding in stools after OPV vaccination was preserved in a substantial proportion of subjects. These findings suggest that this sequential vaccination schedule can maintain herd immunity.

Antibodies, Viral↗
PubMed2001

Hepatitis A virus infection in Taipei in 1999.

BACKGROUND AND PURPOSE: Hepatitis A is a disease that is heavily affected by sanitation status. Hepatitis A is much less prevalent compared with decades ago in Taiwan, as in many rapidly developing regions. Hepatitis A vaccine is still self-paid under the National Health Insurance program and is still not widely utilized by the general public in Taiwan. This seroepidemiologic study evaluated the prevalence of antihepatitis A virus (anti-HAV) seropositivity in Taipei in 1999. METHODS: A total of 1017 serum samples from healthy inhabitants in Taipei were examined for anti-HAV antibody by qualitative enzyme immunoassay. RESULTS: The overall seroprevalence rate was 25.2% (255/1013) in the nonvaccinated population. The seropositivity rate for anti-HAV antibody among children younger than 12 months old was 23.3%. The rates dropped to between 1% and 4.8% among subjects between 1 and 20 years of age. A markedly higher rate of 40% was observed in subjects aged between 20 and 30 years. The seropositivity rate in subjects aged 31 to 50 was 80%. More than 90% of subjects older than 50 years were seropositive. The vaccination rate was low (0.5%). CONCLUSION: Our findings indicate that Taipei is an area of intermediate endemicity for hepatitis A virus. To achieve better herd immunity, a more active approach to the adoption of hepatitis A vaccine is warranted.

Adolescent↗
PubMed2001

Transthoracic and transesophageal echocardiographic diagnosis of aneurysm of the sinus of Valsalva: a review of five year experience.

BACKGROUND: Aneurysms of the sinus of Valsalva (SVA) are uncommon congenital lesions. The clinical presentations vary from asymptomatic to progressive heart failure following rupture of the aneurysm into an adjacent cardiac chamber. Retrograde aortogram is the diagnostic tool of choice preoperatively. Recent studies have demonstrated that the SVA can be accurately diagnosed using transthoracic two-dimensional, and color Doppler flow mapping, even for surgical preparation without cardiac catheterization. We report our 5-year experience of transthoracic echocardiography (TTE) and transesophageal echocardiography (TEE) in the evaluation of SVA. METHODS: Eleven adult patients with SVA with or without rupture were studied using both TTE and TEE. All of the diagnoses were subsequently comfirmed by either cardiac catheterization or surgical findings. RESULTS: Aneurysms originated in the right coronary sinus (n = 9) and noncoronary sinus (n = 2); they ruptured into the right ventricle in 5 patients and the right atrium in 5 patients. An unruptured right SVA was noted in 1 patient. Both TTE and TEE could identify the site of the aneurysm, rupture sites, and the receiving chamber equally well. Co-existent cardiac lesions included 11 cases of valvular aortic regurgitation (mild in 7, moderate in 2 and severe in 2). Two cases of perimembranous type ventricular septal defect (VSD) and 6 cases of supracristal type VSD (including 1 case of tetraology of Fallot, 3 supracristal, 1 muscular and 1 subaortic) were noted. Three cases were complicated with valvular vegetations (1 aortic valve, 1 aortic and tricuspid valve and 1 aortic and pulmonic valve). One patient had patent ductus arteriosus and 2 patients had pulmonic valvular stenosis. CONCLUSIONS: TEE provides clearer definition for the detailed anatomy of the ruptured sac and co-existent cardiac lesions than TTE through high resolution and closer approach. We conclude that TEE is a powerful complementary diagnostic tool in the evaluation of patients with SVA. TEE also provides additionally useful information for guiding the surgical approach and for assessing the operative results even without cardiac catheterization.

Adult↗
PubMed2001

Empirical monotherapy with meropenem in serious bacterial infections in children.

The efficacy and safety profile of meropenem were analyzed according to data collected from hospitalized pediatric patients aged 4 days to 20 years who had serious bacterial infections and were treated in a major teaching hospital in Taipei. Of the 53 patients enrolled, 47 were analyzed for clinical efficacy and 53 for safety. The satisfactory clinical response rate was 57% in lower respiratory tract infection, 58% in septicemia, 100% in complicated urinary tract infection, osteomyelitis, and central nervous system infection, 83% in skin and soft tissue infection, and 93% in intra-abdominal infection. Eleven (21%) patients experienced adverse events related to meropenem. The most commonly observed adverse reactions were elevated hepatic enzymes (7.5%), increased alkaline phosphatase (3.8%), and thrombocytosis (3.8%). There was no meropenem-related seizure, withdrawal, or death. The results of this study suggested that meropenem is well tolerated even in young infants, and is effective in treating serious childhood bacterial infection. However, this study also identified a proportion of hospitalized pediatric patients with isolates that were resistant to meropenem. The trends in meropenem resistance among nosocomially acquired bacteria should be monitored closely.

Adult↗
PubMed2000

Reversal of TNF-alpha resistance by hyperthermia: role of mitochondria.

The aim of this study is to examine the effect of hyperthermia on tumour necrosis factor-alpha (TNF-alpha) resistance in L929-11E cells. L929-11E is a TNF-alpha resistant variant derived from L929 cells, a commonly used model for TNF-alpha study. Based on the results from flow cytometry and Western blotting, hyperthermia (43 degrees C, 3 h) was found to induce apoptosis, mitochondrial potential (delta psi(m)) depolarization and release of cytochrome c in L929-11E cells. Similar responses were found in L929 cells when treated with TNF-alpha. Heating at 43 degrees C for 1 h did not significantly damage the mitochondria of L929-11E cells but partially reversed their resistance to TNF-alpha. When L929-11E cells were sequentially treated with heating (43 degrees C, 1 h) and TNF-alpha, a more severe damage in mitochondria was observed. Taken together, our results indicate (1) hyperthermia induced apoptosis in L929-11E cells via mitochondrial damages in a way very similar to the action of TNF-alpha in L929 cells, (2) hyperthermia could be used to overcome TNF-alpha resistance by altering mitochondrial activities and (3) L929-11E and its parental cells provide a useful model in elucidating the signalling linkage between TNF-alpha receptor and mitochondria.

Cell Line↗