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Biomedical subjects

C H Chen

Publications and source records attributed to C H Chen.

At least 37 records · Page 2Linked to original sources
PubMed2004

Central adenoid cystic carcinoma of the mandible manifesting as an endodontic lesion.

AIM: To present a case of adenoid cystic carcinoma (ACC) in the mandible, and manifesting as a periapical lesion. SUMMARY: A 56-year-old male suffered from pain around the right mandibular first molar for approximately 1 week. Oral examination revealed that the involved tooth was restored by a full coverage crown with no obvious abnormalities. A periapical radiograph revealed two ill-defined radiolucencies associated with the tooth, one over the mesial and another over the distal roots of the tooth; incomplete root filling and furcation involvement also being noted. The affected tooth was extracted based on the clinical impression of apical periodontitis. The surrounding tissue of the root apex was curetted and sent for histopathological examination, which revealed ACC. KEY LEARNING POINTS: Adenoid cystic carcinoma affecting the mandible may mimic a periapical lesion. Proper diagnosis of such a lesion is dependent on thorough clinical, radiographic and microscopic examinations. Such a case highlights the benefits of biopsy and histological examination of collected tissues. Diagnosis of lesions in the mandible should include salivary gland tumours.

Carcinoma, Adenoid Cystic↗
PubMed2004

Influences of follicular size on parthenogenetic activation and in vitro heat shock on the cytoskeleton in cattle oocytes.

The availability of cow ovaries from the slaughterhouse has been very limited in Taiwan. To maximize the use of cow ovaries for research purposes, whole ovary dissection was performed and the developmental competence of the oocytes derived from different sizes of follicles was assessed by the rates of in vitro maturation (IVM) and parthenogenetic activation of the oocytes in Experiment 1 (Exp 1). Cumulus-oocyte complexes (COCs) derived from small (1-2 mm) and large (3-8 mm) follicles were subjected to standard IVM culture for 24 h. Mature oocytes were selected and then parthenogenetically activated using A23187 (5 microm, 5 min) or thimerosal (200 microm, 10 min) alone or combined with 6-dimethylaminopurine (2.5 mm and 3.5 h, respectively). Activation rates of the oocytes, neither from the large nor small follicles, were affected by different activation treatments (single or combined stimuli). Whereas maturation rates for the oocytes from large follicles were superior to those from small follicles in both the single (59% vs 45%) and combined treatments (76% vs 40%; p < 0.05). To understand how prolonged heat shock (HS) influences cytoskeletal configurations of mature bovine oocytes, in Experiment 2 (Exp 2), matured oocytes derived from large follicles were randomly allocated to different durations of HS treatments at 41.5 degrees C for 0 (C0h, control, n = 12), 1 (HS1h, n = 28), 2 (HS2h, n = 31), and 4 h (HS4h, n = 30). An additional control group was cultured for 4 h without HS (38.5 degrees C, 4 h, n = 35). Alterations in nuclear structures, microtubules (MTs), and microfilaments (MFs) of the oocytes were examined. Abnormalities in the chromosomes, spindle MTs and the percentages of oocytes with cytoplasmic MTs increased with time of HS treatment. The intensity of the MF distribution in the HS oocytes was also altered. Significant changes in the cytoskeleton after HS may be associated with the reduced development under hyperthermia and, perhaps, with the low pregnancy rates of the animals during hot seasons.

Animals↗
PubMed2004

Elevated serum levels of a c-erbB-2 oncogene product in oral squamous cell carcinoma patients.

OBJECTIVES: Amplification of the proto-oncogene c-erbB-2 (HER-2/neu) has been shown to be a prognostic marker in many kinds of cancer including oral squamous cell carcinoma (OSCC). In order to obtain further information on the c-erbB-2 gene product p185, it is necessary to quantify expression levels. In this study we used an enzyme-linked immunosorbent assay (ELISA) for the extracellular domain of p185 to determine whether a soluble oncoprotein fragment can be detected in the serum of OSCC patients. METHOD: Sera from 84 OSCC patients, 51 breast cancer patients (as positive controls), and 15 healthy controls were assayed in an ELISA. To study c-erbB-2 overexpression in OSCC, and breast cancer tissue samples we used an immunohistochemical technique. RESULTS: The mean serum value (ng/ml, mean/SD) for the normal controls was 8.46/1.29. We chose the 95% level of normal controls as a cut-off to distinguish individuals with elevated levels. The breast cancer patients' and OSCC patients' serum values were 13.83/6.82 and 13.1/4.56, respectively. Significant differences (P < 0.0001) were observed between normal control and OSCC, normal control and the breast cancer group. Immunohistochemically detectable p185 (intermediate to high) was noted in 30 of 61 OSCC, and 24 of 51 breast cancer patients. There was a trend of association of serum oncoprotein fragment levels with tumor stages, but not with tumor sizes, nodal stages, metastases, and oral habits including betel quid chewing, alcohol drinking and smoking in the OSCC group. CONCLUSION: The results of the present study raise the possibility that soluble c-erbB-2 protein levels in serum is a useful parameter for monitoring the disease status as well as the effect of therapy on patients with OSCC.

Adult↗
PubMed2004

Risk factors for peptic ulcer disease in renal transplant patients--11 years of experience from a single center.

BACKGROUND: Peptic ulcer disease is a common complication among renal transplant recipients and causes significant morbidity and mortality. METHODS: From 1990 through 2000, 465 renal transplant patients were followed-up in our institute. Most patients received corticosteroids and cyclosporine-based immunosuppressive regimen. About one third (n = 156) of them received mycophenolate mofetil. Patients with endoscopy-proved peptic ulcer disease were identified by reviewing medical records. Possible risk factors were analyzed by univariate analysis and multiple logistic regression analysis. RESULTS: Among 465 kidney transplant patients, there were 181 (38.9%) who suffered at least 1 episode of peptic ulcer disease. The most frequent types of peptic ulcer disease were gastritis, gastric ulcer, duodenal ulcer, esophagitis, duodenitis and esophageal ulcer. By multivariate analysis, the use of methylprednisolone pulse therapy (odds ratio = 3.954, 95% confidence interval = 3.154-18.312, p = 0.03) and history of pre-transplant peptic ulcer disease (odds ratio = 7.599, 95% CI = 1.211-12.905, p < 0.0001) were independent risk factors for posttransplant peptic ulcer disease. CONCLUSIONS: Our findings demonstrated that renal transplant patients who undergo methylprednisolone pulse therapy for acute rejection or who have a history of pre-transplant peptic ulcer disease carry a high risk for the development of peptic ulcer disease and deserve intensive antiulcer treatment.

Adolescent↗
PubMed2003

Triplet-to-singlet exciton formation in poly(p-phenylene-vinylene) light-emitting diodes.

The triplet to singlet exciton formation ratio in a MEH-PPV light-emitting diode is measured by comparing the triplet-induced absorptions with optical and electric excitations at the same singlet exciton density. The ratio is a strong universal decreasing function of the averaged electric field. Using 4 ns for singlet to triplet intersystem crossing time, the ratio is significantly larger than the spin-independent value 3 at intermediate field but is reduced to about 2 for higher field.

Journal Article↗
PubMed2003

Matrix-assisted laser desorption/ionization detection of polymerase chain reaction products by utilizing the 5'-3' exonuclease activity of Thermus aquaticus DNA polymerase.

The 5'-3' exonuclease activity of DNA polymerase was utilized in the polymerase chain reaction system to generate a specific signal concomitant with amplification. These signals were detected by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOFMS). This method obviates the need to perform extensive DNA purification of reaction products that is often necessary for detecting larger DNA molecules by mass spectrometry. Oligonucleotides complementary to the internal region of the amplicon are degraded by the 5'-3' exonuclease activity and the degradation products are analyzed by MALDI mass spectrometry. We refer to this assay as the Exo-taq assay or probe degradation assay. This method should be amenable to automation.

DNA↗
PubMed2003

Epidemiology of otitis media in Chinese children.

From May to July 2001, 3013 Chinese children, aged 3-6 years old, from 19 kindergartens in Kaohsiung were examined for the prevalence of otitis media. A senior paediatric otolaryngologist performed examinations. Tympanometric and otoscopic records were combined for assessment of middle ear status. The prevalence rate of otitis media was 9.82% for all children, 5.24% for middle ear effusion and 5.34% for retracted tympanic membrane. The prevalence rates of otitis media in different age groups were as follows: 11.3% for 3-year-olds, 12.4% for 4-year-olds, 11.8% for 5-year-olds, and 6.1% for 6-year-olds. Considering the genetic factors and the previous history of otitis media, there was a significant difference between the normal group and the sick group.

Acoustic Impedance Tests↗
PubMed2003

Free radical-scavenging activity of Taiwanese native plants.

The 70% aqueous acetone extracts of ten Taiwanese native plants were evaluated by various antioxidant assays, including 1, 1-diphenyl-2-picrylhydrazyl (DPPH), hydroxyl (.OH) radicals, and reducing power assay. In the present study, extracts of Acer buerferianum var. formosanum, Cleyera japonica var. morii, Cyclobalanopsis stenophylla var. stenophylloides, and Machilus zuihoensis exhibited stronger activity against DPPH radicals, and their IC50 values ranged from 5.4 to 8.3 microg/ml. The ten selected extracts effectively inhibited the formation of .OH generated in the Fenton reaction system. Among the extracts whose reducing power activities were determined, A. buerferianum var. formosanum, C. japonica var. morii, C. stenophylla var. stenophylloides, Eriobotrya deflex, and M. zuihoensis showed high activity. The results indicate the 70% aqueous acetone extracts of A. buerferianum var. formosanum, C. japonica var. morii, C. stenophylla var. stenophylloides, and M. zuihoensis with great potency in these assay systems and may be candidates for the development of natural antioxidants.

Acer↗
PubMed2003

Prevalence and clinical implications of hepatitis B virus genotypes in southern Taiwan.

BACKGROUND: Hepatitis B virus (HBV) infection is a major health problem. HBV genotypes may be associated with progression of liver disease. The distribution and clinical implications of HBV genotypes in southern Taiwan are evaluated. METHODS: We used a polymerase chain reaction-restriction fragment length polymorphism genotyping method to determine HBV genotypes. RESULTS: The genotype distribution for 265 patients with chronic HBV infection was as follows: A, 3 (1%); B, 158 (60%); C, 90 (34%); D, 7 (2.5%); E, 0: F, 0; and unclassified, 7 (2.5%). Compared with genotype B patients, genotype C patients had a higher hepatitis B e antigen positive rate and higher fibrosis score. There was no significant difference in the mean age between genotype B and genotype C patients with hepatocellular carcinoma (HCC). However, when patients were stratified by age, the prevalence of genotype C was significantly higher in young HCC patients (<50 years of age) than in age-matched asymptomatic carriers (40% versus 10%, P < 0.001). Using multivariate analysis, the significant risk factors for advanced liver disease (cirrhosis or HCC) for patients with chronic HBV infection were old age, male gender and genotype C. CONCLUSIONS: These results suggest that genotype C is associated with more severe liver diseases than the B variant.

Adolescent↗
PubMed2003

Recycling and reuse of wastewater from a new-developed community using sand filtration, ultrafiltration, and ozonation.

In this study, the pilot apparatus combined with sand filtration, ozonation and ultrafiltration was established. Wastewater from the secondary treatment effluent in the new-developed community was taken as the sample for looking into the feasibility of domestic wastewater reuse and recycling. The test results by sand filtration, sand filtration/ultrafiltration, sand filtration/ozonation, and sand filtration/ultrafiltration/ozonation were compared for looking for appropriate treatment processes applied in the domestic wastewater reuse and recycling. Finally, cost analysis was carried out and sand filtration/ozonation process was suggested to be one of the best processes. The total cost is about 0.1-0.32 USD dollars per cubic meter of produced water by considering the capital and operation cost for five years in the small domestic wastewater treatment plant (50-750 CMD).

Conservation of Natural Resources↗
PubMed2003

Biotin-enhanced fragmentation for direct deoxyribonucleic acid sequencing using matrix-assisted laser desorption/ionization mass spectrometry.

Fragmentation of synthetic oligonucleotides under the influence of biotin was investigated using 3-hydroxypicolinic acid (3-HPA) as a matrix-assisted laser desorption/ionization (MALDI) matrix. Addition of biotin into the sample enhanced fragmentation of the oligonucleotide between bases. However, when the biotin was tagged to the 5'-terminus of the oligonucleotide, enhancements were observed not only in desorption/ionization efficiency but also in the fragmentation of molecular ions. The protonation/deprotonation process occurs on the tagged biotin is a possible reason for the enhancement in desorption/ionization. Site-specific backbone cleavage fragmentation patterns were observed. The sequences of oligonucleotides can be obtained from their fragment ions. The direct sequencing of a 5'-biotin-tagged 25-mer is demonstrated.

Base Sequence↗
PubMed2003

Hip arthroplasty in patients with cirrhosis of the liver.

We retrospectively reviewed 45 hip arthroplasties which were performed over a period of 20 years in 38 patients with cirrhosis of the liver. There was a high perioperative 30-day complication rate (26.7%). Advanced cirrhosis was associated with a higher risk of complications (p = 0.004) as also was increased age, a high level of creatinine, a low level of albumin, a low platelet count, ascites, encephalopathy and an increased operative blood loss. The survival of the prosthesis at five years was 77.8% and infection was a major cause of failure. In view of the high rate of early complications and the limited longevity of the prosthesis, surgeons who perform hip arthroplasty on such patients should counsel them appropriately preoperatively.

Adult↗
PubMed2002

Percolative Superconductivity in Mg1-xB2.

Our results from various transport experiments on Mg1-xB2 indicate a surprising effect associated with the presence of a Mg deficiency in MgB2: the phase separation between Mg-vacancy rich and Mg-vacancy poor phases. The Mg-vacancy poor phase is superconducting, but the insulating nature of the Mg-vacancy rich phase probably originates from the Anderson (disorder-induced) localization of itinerant carriers. Furthermore, electron diffraction measurements indicate that within vacancy-rich regions these defects tend to order with intriguing patterns. This electronic phase separation in Mg1-xB2 shows similar, but also distinct characteristics compared with that observed in La(2)CuO(4+delta).

Journal Article↗
PubMed2002

Electrochemistry: building on bubbles in metal electrodeposition.

In the electrodeposition of metals, a widely used industrial technique, bubbles of gas generated near the cathode can adversely affect the quality of the metal coating. Here we use phase-contrast radiology with synchrotron radiation to witness directly and in real time the accumulation of zinc on hydrogen bubbles. This process explains the origin of the bubble-shaped defects that are common in electrodeposited coatings.

Journal Article↗
PubMed2002

Formation of isomorphic Ir3+ and Ir4+ octamers and spin dimerization in the spinel CuIr2S4.

Inorganic compounds with the AB2X4 spinel structure have been studied for many years, because of their unusual physical properties. The spinel crystallographic structure, first solved by Bragg in 1915, has cations occupying both tetrahedral (A) and octahedral (B) sites. Interesting physics arises when the B-site cations become mixed in valence. Magnetite (Fe3O4) is a classic and still unresolved example, where the tendency to form ordered arrays of Fe2+ and Fe3+ ions competes with the topological frustration of the B-site network. The CuIr2S4 thiospinel is another example, well known for the presence of a metal-insulator transition at 230 K with an abrupt decrease of the electrical conductivity on cooling accompanied by the loss of localized magnetic moments. Here, we report the determination of the crystallographic structure of CuIr2S4 below the metal-insulator transition. Our results indicate that CuIr2S4 undergoes a simultaneous charge-ordering and spin-dimerization transition-a rare phenomenon in three-dimensional compounds. Remarkably, the charge-ordering pattern consists of isomorphic octamers of Ir83+S24 and Ir84+S24 (as isovalent bi-capped hexagonal rings). This extraordinary arrangement leads to an elegant description of the spinel structure, but represents an increase in complexity with respect to all the known charge-ordered structures, which are typically based on stripes, slabs or chequerboard patterns.

Journal Article↗