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Y S Chen

Publications and source records attributed to Y S Chen.

At least 37 records · Page 2Linked to original sources
PubMed2003

On formation of CaO-Al(2)O(3)-SiO2 glass-ceramics by vitrification of incinerator fly ash.

CaO-Al(2)O(3)-SiO(2) system glass ceramics of incinerator fly ash have been prepared by vitrification and then heat-treated in different conditions. The thermal molten process (TMP) was applied to heat treat vitrified samples at high temperatures whereas in the powder sintering process water-quenched vitrified samples were ground into powder and then sintered at high temperatures. Gehlenite was found present as the major phase in all treated samples. Treated samples in general exhibited good leachability characteristics as well as chemical durability, except in the HCl solution. Microstructure and physical properties varied with the treatment condition. Fine and relatively high dense structures with desirable properties were obtained for samples treated by the TMP. For both processes, higher temperature treatments caused crystal growth and thus poor properties were attained. Good physical and mechanical properties achieved at 900-950 degrees C in this study imply the treated samples have attractive potential for engineering applications.

Aluminum Oxide↗
PubMed2003

Curcumin inhibited the arylamines N-acetyltransferase activity, gene expression and DNA adduct formation in human lung cancer cells (A549).

It is well known that N-acetyltransferase (NAT) plays an important role in the arylamine metabolism. We analysed the response of A549 human lung cancer cells for N-acetylation of 2-aminofluorene (AF) to curcumin. After curcumin treatment, the NAT activity was examined by HPLC, AF-DNA adduct formation was examined by HPLC, and NAT gene expression by polymerase chain reaction were detected. The NAT activity in the human A549 cells and cytosols was suppressed by curcumin in a dose-dependent manner. The results also demonstrated that gene expression (NAT1 mRNA) in human lung A549 tumor cells was inhibited and decreased by curcumin. After the incubation of human lung A549 tumor cells with AF with or without curcumin co-treatment, the cells were recovered and DNA was prepared and hydrolyzed to nucleotides. The adducted nucleotides were extracted into butanol and analyzation of AF-DNA adducts was done by HPLC. The results also demonstrated that curcumin decreases AF-DNA adduct formation in the human lung A549 tumor cells.

Acetylation↗
PubMed2002

Treatment and recycling of incinerated ash using thermal plasma technology.

To treat incinerated ash is an important issue in Taiwan. Incinerated ashes contain a considerable amount of hazardous materials such as dioxins and heavy metals. If these hazardous materials are improperly treated or disposed of, they shall cause detrimental secondary contamination. Thermal plasma vitrification is a robust technology to treat and recycle the ash residues. Under the high temperature plasma environment, incinerated ashes are vitrified into benign slag with large volume reduction and extreme detoxification. Several one-step heat treatment processes are carried out at four temperatures (i.e. 850, 950, 1,050 and 1,150 degrees C) to obtain various "microstructure materials". The major phase to form these materials is a solid solution of gehlenite (Ca2Al2SiO7) and åkermanite (Ca2MgSi2O7) belonging to the melilite group. The physical and mechanical properties of the microstructure materials are improved by using one-step post-heat treatment process after plasma vitrification. These microstructure materials with good quality have great potential to serve as a viable alternative for construction applications.

Conservation of Natural Resources↗
PubMed2002

Ginsenoside Rb1 enhances peripheral nerve regeneration across wide gaps in silicone rubber chambers.

Silicone rubber chambers filled with collagen containing ginsenoside Rb1 (GRb1) were used to repair lesioned rat sciatic nerves with 15-mm gaps between stumps. Six weeks after implantation, histology of the nerve regenerated in the chambers filled with GRb1 and collagen contained larger axons than those in the chambers with collagen only. This study showed that the GRb1 could exert a positive influence on nerve regeneration when using silicone rubber tubes.

Animals↗
PubMed2002

Utility and accuracy of template-directed dye-terminator incorporation with fluorescence-polarization detection for genotyping single nucleotide polymorphisms.

There are little independent data available about how well single nucleotide polymorphism (SNP) genotyping technologies perform in the typical molecular genetics laboratory. We evaluated the utility and accuracy of a widely used technology, template-directed dye-terminator incorporation with fluorescence-polarization detection (FP-TDI), in a sample of 177 SNPs selected solely on the basis of map location. Genotypes were generated without optimization using standard protocols. Overall, 81% of the SNPs we studied generated readable genotypes by FP-TDI. Thirty-two SNPs were genotyped in duplicate by PCR-RFLP orfluorescent dye-terminator sequencing. Out of a total of 631 duplicate genotypes, no true discrepancies were detected. The true error rate has a 95% chance of lying between 0 and 6 out of 1000 genotypes. We also tested for deviations from Hardy-Weinberg Equilibrium in 33 SNPs genotyped in 50 unrelated individuals, and no significant deviations were detected. Our FP-TDI data were readily adaptable to automated genotype calling using our own method of cluster analysis, which assigns a probability score to each genotype call. We conclude that FP-TDI is both efficient and accurate. The method can easily fill the needs of SNP genotyping projects at the scale typically used for regional or candidate-gene association studies.

Fluorescence Polarization↗
PubMed2002

The cost effectiveness of dual phase 201Tl thyroid scan in detecting thyroid cancer for evaluating thyroid nodules with equivocal fine-needle aspiration results: the preliminary Taiwanese experience.

The purposes of this study were to assess the helpfulness of dual phase 201Tl thyroid scan for differentiating malignant from benign thyroid lesions in cases of thyroid nodules with equivocal fine-needle aspiration (FNA) biopsy results. In addition, for thyroid nodules with equivocal FNA biopsy results, we try to make a decision analysis model compared the FNA biopsy alone strategy (strategy A) with decision strategy for the assistance of dual phase 201Tl thyroid scan (strategy B) before diagnostic thyroidectomy as thyroid cancer evaluation strategies for hypothetical cohorts of estimated 17,280-29,160 Taiwanese patients/per year with equivocal FNA biopsy results. Based on the findings of surgical histopathology, dual phase 201Tl thyroid scan sensitivity, specificity, and accuracy were 100%, 90%, and 96%, respectively, in cases of 27 thyroid nodules with equivocal FNA biopsy results. In cost effectiveness analysis, the strategy B showed a cost saving of 16,340,480-27,574,560 US dollars in unnecessary diagnostic thyroidectomy cost. The total cost of strategy B showed a cost saving of 13,932,232-23,520,564 US dollars than that of strategy A. The preliminary data indicate that dual phase 201Tl thyroid scan can save the cost of unnecessary diagnostic thyroidectomy in Taiwanese patients with equivocal FNA biopsy results. In addition, we may provide a noninvasive diagnostic method--dual phase 201Tl thyroid scan, as the first priority for Taiwanese patients with equivocal FNA biopsy before diagnostic thyroidectomy under the coverage of the national health insurance system in Taiwan.

Adolescent↗
PubMed2001

Effects of percutaneous electrical stimulation on peripheral nerve regeneration using silicone rubber chambers.

The purpose of this study was to determine whether 0.8-1 mA, 2 Hz of percutaneous electrical stimulation could affect the regeneration of a 10-mm gap of rat sciatic nerve created between the proximal and distal nerve stumps, which were sutured into silicone rubber tubes. Six weeks after implantation, though the group receiving the electrical stimulation had a lower success percentage of regeneration (57%) compared with the controls receiving no stimulation (70%), quantitative histology of the successfully regenerated nerves revealed that the mean values of the axon density, blood vessel number, blood vessel area, and percentage of blood vessel area in total nerve area in the group with the electrical stimulation were all significantly larger than those in the controls (p < 0.05). These results showed that the electrical stimulation could elicit rehabilitating effects on the regenerated nerves.

Animals↗
PubMed2001

Single imaging modality evaluation of living donors in liver transplantation: magnetic resonance imaging.

BACKGROUND: Liver graft size, anatomy of the bile duct and the vascular inflow and outflow are essential for living related liver transplantation (LRLT). Preoperative delineation of those variations that would change the operative procedure to achieve a successful result especially in an emergency condition. PURPOSE: Our aim was to develop a rapid and noninvasive imaging diagnostic method for the detection of anatomical variants that is mandatory for a safe operation when selecting potential liver transplant living donors. We used a different magnetic resonance (MR) imaging technique, which enabled to us to exploit the anatomical landmark of the liver, signal enhancement of blood flow in the abdomen, and the intrahepatic biliary routes inside the liver. Then, with the help of Advantage Window workstation reconstruction, the reconstructed single vascular or biliary systems were displaced in a three-dimensional fashion and the whole examination finished within 30 min. METHODS: Modification of the standard MR technique was performed on a superconductive 1.5T whole body image scanner, MR arteriogaphy, venography, and cholangiography with three-dimensional reconstruction in evaluating the anatomy of the hepatic arteries, hepatic veins, portal venous system, bile ducts, and liver size in potential liver transplant living donors. These anatomical structures were compared with traditional imaging methods. RESULTS: In all 38 cases, as well as delineation of the portal vein detail to the segmental level was satisfactorily obtained in this MR study. The images were well displayed in a three-dimensional fashion, which had good correlation with images from traditional imaging modalities and operative findings. In 86.8% cases, the MR arteriography was well matched with the celiac angiography. Of those 17 operative cases, estimation of liver volume was well correlated with the liver graft within 3.9-12.5% variation. In the major hepatic vein, we obtained 100% accuracy and 88.2% in the minor branches. Of 12 donors received intraoperative cholangiography during liver donation, good correlation of biliary anatomy was achieved. One donor was excluded from graft donation due to the complicated arterial supply to the left liver. According to the anatomical variation, surgical procedures in graft harvesting and anastomosis were readjusted and no major complications were found in those donors and all recipients survived after liver transplantation. CONCLUSION: MR volumetry, venography, angiography, and cholangiography with three-dimensional reconstruction is sufficient for all major imaging evaluation. It may replace the traditional conventional catheter angiography, computed tomography, sonography and endoscopic retrograde cholangiography as a single investigation in the evaluation of the potential liver transplant donors. Angiography is only valuable in suboptimal cases and intraoperative cholangiography is only performed in biliary ductile variants.

Adult↗
PubMed2001

Assessment of donor fatty livers for liver transplantation.

AIM: The effect of fatty liver on graft survival, especially with reference to macrovesicular and microvesicular steatosis, is still uncertain. This preliminarily study was designed to create a noninvasive method for the quantification of the hepatic fat content in vivo and to establish provisional criteria for the assessment of fatty donor livers before liver transplantation among transplant surgeons, radiologists, and pathologists. METHODS AND MATERIALS: Different degrees of rat fatty liver model were established by feeding rats a diet deficient in choline and methionine for different periods of time. Computed tomography (CT) with test tubes containing variable percentages of fat equivalent substance were used to assess the severity of fatty change of the rat liver. This was then correlated with the histological classification, level of hepatic enzymes, and graft survival. RESULTS: Linear correlation between the fat volume fraction added to the test tubes and CT density were found. The process of producing a fatty liver via diet alteration peaked at week 3. At this time hepatic enzymes, radiological fat content, and posttransplantation survival were worse (P=0.013), compared with other time points. Radiological assessment of fatty liver correlated well with survival and serum glutamic oxaloacetic transaminase and glutamic pyruvate transaminase levels. CONCLUSION: Severe microvesicular steatosis does not influence recipient survival, however, macrovesicular steatosis affects graft survival. Caliber CT is a practical and simple method that allows an accurate noninvasive quantitative assessment of hepatic fatty infiltration. It has potential to be a useful parameter for the assessment of donor livers for clinical liver transplantation.

Animals↗
PubMed2001

Hemorrhage following pediatric tonsillectomy before puberty.

OBJECTIVE: Control of postoperative bleeding, considered as the major complication following tonsillectomy, serves as a landmark for the safety of the operation. There is a constant decrease of the concentration of hemoglobin during childhood with lowest values around 6 years of age with normal values at the beginning of puberty accompanied by a constant decrease of the number of platelets after birth. Dehydration, poor oral intake and airway problems are predominant complications in early childhood. A retrospective study was undertaken to evaluate if the incidence of bleeding is associated with certain age groups in pediatric patients. We assessed if there is a questionable higher risk for blood transfusions due to the age-specific lower hemoglobin concentration in children. METHODS: Between January 1988 and August 2000, 2330 patients under 12 years of age underwent tonsillectomy, with or without adenoidectomy, in St. Anna Hospital, Duisburg. Group A (age<6 years) consisted of 1467 patients of whom 59.6% were male. Group B (aged 6-12 years) consisted of 863 patients, of whom 48.1% were male. RESULTS: Postoperative bleeding from the tonsillar fossae requiring treatment under general anesthesia occurred in group A (1%) and B (2.3%). Bleeding from the adenoidectomy site was treated in group A (0.3%) and B (0.3%). Primary bleeding occurred in the majority of patients in both groups group A (55%) and group B (75%). The latest bleeding was observed 6 days (group A) and 10 days (group B) following surgery, due to statistical analysis the difference was found to be significant (P<0.025). In group A there was one 42-month-old boy who died due to massive bleeding despite ligature of the external carotid artery and blood transfusions. Statistical evaluation shows a significant increase of postoperative bleeding with age (P=0.024). No blood transfusion was required in other patients. CONCLUSION: Tonsillectomy can be safely performed in children under 6 years of age with no increased risk of postoperative bleeding or risk of receiving blood transfusion. Rare cases of secondary hemorrhage seem to occur more frequently in younger children and should be treated immediately under general anesthesia to avoid severe complications.

Adenoidectomy↗
PubMed2001

Reactive oxygen species modulate angiotensin II-induced beta-myosin heavy chain gene expression via Ras/Raf/extracellular signal-regulated kinase pathway in neonatal rat cardiomyocytes.

Angiotensin II (Ang II) causes cardiomyocytes hypertrophy. Cardiac beta-myosin heavy chain (beta-MyHC) gene expression can be altered by Ang II. The molecular mechanisms are not completely known. Reactive oxygen species (ROS) are involved in signal transduction pathways of Ang II. However, the role of ROS on Ang II-induced beta-MyHC gene expression remains unclear. Here we found that Ang II increased beta-MyHC promoter activity and it was blocked by Ang II type 1 receptor antagonist losartan. Ang II dose-dependently increased the intracellular ROS. Cardiomyocytes cotransfected with a dominant negative mutant of Ras (RasN17), Raf-1 (Raf301), or a catalytically inactive mutant of extracellular signal regulated kinase (mERK2) inhibited Ang II-induced beta-MyHC promoter activity, indicating Ras/Raf/ERK pathway was involved. Antioxidants such as catalase or N-acetyl-cysteine decreased Ang II-activated ERK phosphorylation and inhibited Ang II-induced beta-MyHC promoter activity. These data indicate that Ang II increases beta-MyHC gene expression in part via the generation of ROS.

Angiotensin II↗
PubMed2001

Interventional radiologic procedures in liver transplantation.

Postoperative biliary and vascular complications contribute significantly to morbidity and mortality in liver transplantation. Interventional radiologists are an integral part of the multidisciplinary team necessary for optimizing the management of these complications. During a 15-year period, 39 cadaveric and 25 living related liver transplantations were performed at the Chang Gung Memorial hospital, Taiwan. Of 64 liver transplant recipients, 9 (3 adult and 6 pediatric) underwent 13 interventional radiological procedures for the treatment of biliary sludge-casts (n = 2), bile duct occlusion or stenosis (n = 2), hepatic veins thrombosis (n = 1), hepatic veins stenosis (n = 1), portal vein stenosis with splenorenal shunting (n = 1), biloma (n = 1), and infected fluid collection or ascites (n = 4). Antegrade or retrograde interventional approach was used to successfully treat all biliary complications, and all percutaneous drainage procedures were effective in the control of intra-abdominal fluid collections. Portal vein stenosis was treated by balloon dilatation, and the associated splenorenal shunt was closed by metallic coil embolization via transhepatic catheterization of the portal vein. Hepatic vein stenosis was effectively treated by balloon dilatation and expandable metallic stent deployment via transfemoral and jugular venous approaches, respectively. Hepatic vein thrombosis was only partially lysed by transvenous streptokinase administration, and surgical thrombectomy was needed to achieve complete recanalization. The total success rate of the interventional procedures was 92 % with no procedure-related complications. The overall survival rate in this series is 89 %, and all patients who underwent living related liver transplantation maintain to date a 100 % survival rate. We can conclude that interventional radiological procedures are very useful for managing biliary and vascular complications after liver transplantation. These techniques provide a cure in most situations, thus obviating the need for further surgical intervention or re-transplantation.

Adolescent↗
PubMed2001

Eosinophilic meningitis caused by Angiostrongylus cantonensis: report of 17 cases.

PURPOSE: To describe two outbreaks of Angiostrongylus cantonensis infection that occurred in Kaohsiung, Taiwan, during 1998 and 1999, and to characterize the source of the outbreaks and the clinical manifestations of the disease. SUBJECTS AND METHODS: We performed a retrospective cohort study among Thai laborers with eosinophilic meningitis who ate raw snails (Ampullarium canaliculatus), as well as an environmental surveillance of larvae in snails. RESULTS: We enrolled 17 Thai laborers in whom severe headache and eosinophilia developed within 4 to 23 days after eating raw snails. Twelve (71%) developed eosinophilic meningitis. Third-stage larvae were found in the cerebrospinal fluids of 2 patients and in all 12 tested snails. Specific antibodies to A. cantonensis were detected in serum from 16 of the patients and in cerebrospinal fluid from 5 of the patients. Central nervous system manifestations included headache (n = 17 [100%]), fever (n = 11 [65%]), Brudzinski's sign/stiff neck (n = 11 [65%]), hyperesthesia (n = 3 [18%]), cranial nerve palsy (n = 2 [12%]), diplopia (n = 2 [12%]), and ataxia (n = 1 [6%]). Laboratory findings included peripheral eosinophilia (n = 15 [88%]) and cerebrospinal fluid eosinophilia (n = 12 [71%]); elevated immunoglobulin (Ig) E levels (n = 13 [100%]); and transient increases in white blood cell count (n = 7 [41%]) and in serum levels of creatine kinase (n = 7 [41%]), transaminase (n = 3 [18%]), and lactate dehydrogenase (n = 2 [12%]). The severity of illness and eosinophilia were correlated with the number of ingested snails. Meningeal and basal ganglion enhancement was noted on magnetic resonance imaging in several patients. Treatment with mebendazole combined with glucocorticosteroids appeared to shorten the course of the infection, but not the number of relapses. The eosinophil count fell to normal within 3 months, but IgE levels remained elevated for as long as 6 months. All patients recovered with minimal neurologic sequelae. CONCLUSION: Eosinophilic meningitis caused by A. cantonensis should be considered in patients who have headache or central nervous system manifestations after eating raw snails.

Adult↗