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Biomedical subjects

C Y Wei

Publications and source records attributed to C Y Wei.

16 recordsLinked to original sources
PubMed2005

Factors influencing arsenic accumulation by Pteris vittata: a comparative field study at two sites.

This study compared the factors influencing arsenic (As) accumulation by Pteris vittata at two sites, one containing As along with Au mineralization and the other containing Hg/Tl mineralization. The soils above these two sites contained high As concentrations (26.8-2955 mg kg(-1)). Although the As concentration, pH, soil cation exchange capacity and plant biomass differed significantly between the two sites, no differences were observed in the As concentrations in the fronds and roots, or the translocation factors, of P. vittata, suggesting that this species has consistent As hyperaccumulation properties in the field. The As concentration in the fronds was positively related to phosphorus (P) and potassium (K), but negatively related to calcium (Ca), at one site. This suggested that P, K and Ca influenced As accumulation by P. vittata in the field.

Arsenic↗
PubMed2001

Oxidative stress in human aging and mitochondrial disease-consequences of defective mitochondrial respiration and impaired antioxidant enzyme system.

Respiratory function of mitochondria is compromised in aging human tissues and severely impaired in the patients with mitochondrial disease. A wide spectrum of mitochondrial DNA (mtDNA) mutations has been established to associate with mitochondrial diseases. Some of these mtDNA mutations also occur in various human tissues in an age-dependent manner. These mtDNA mutations cause defects in the respiratory chain due to impairment of the gene expression and structure of respiratory chain polypeptides that are encoded by the mitochondrial genome. Since defective mitochondria generate more reactive oxygen species (ROS) such as O2- and H2O2 via electron leak, we hypothesized that oxidative stress is a contributory factor for aging and mitochondrial disease. This hypothesis has been supported by the findings that oxidative stress and oxidative damage in tissues and culture cells are increased in elderly subjects and patients with mitochondrial diseases. Another line of supporting evidence is our recent finding that the enzyme activities of Cu,Zn-SOD, catalase and glutathione peroxidase (GPx) decrease with age in skin fibroblasts. By contrast, Mn-SOD activity increases up to 65 years of age and then slightly declines thereafter. On the other hand, we observed that the RNA, protein and activity levels of Mn-SOD are increased two- to three-fold in skin fibroblasts of the patients with CPEO syndrome but are dramatically decreased in patients with MELAS or MERRF syndrome. However, the other antioxidant enzymes did not change in the same manner. The imbalance in the expression of these antioxidant enzymes indicates that the production of ROS is in excess of their removal, which in turn may elicit an elevation of oxidative stress in the fibroblasts. Indeed, it was found that intracellular levels of H2O2 and oxidative damage to DNA and lipids in skin fibroblasts from elderly subjects or patients with mitochondrial diseases are significantly increased as compared to those of age-matched controls. Furthermore, Mn-SOD or GPx-1 gene knockout mice were found to display neurological disorders and enhanced oxidative damage similar to those observed in the patients with mitochondrial disease. These observations are reviewed in this article to support that oxidative stress elicited by defective respiratory function and impaired antioxidant enzyme system plays a key role in the pathophysiology of mitochondrial disease and human aging.

Aging↗
PubMed1999

Determination of the sensitivity and specificity of PCR assays using different target dnas for the detection of Mycobacterium tuberculosis.

To establish a sensitive, specific and reproducible PCR assay for the detection of Mycobacterium tuberculosis, we evaluated three target DNAs: IS6110, 65 kDa heat shock protein gene; and mtp40 genomic fragment. We purified genomic DNA from 15 mycobacterial strains including four M. tuberculosis isolates, four M. bovis BCG isolates, and one of each for M. fortuitum, M. avium, M. intracellulare, M. szulgai, M. scrofulaceum, M. chelonei, and M. gordonae from the culture and used them as the template DNA. We studied 3 primer sets for IS6110, 2 primer sets for 65 kDa, and 3 primer sets for mtp40. Depending on the assay, these primer sets were used in the single-step PCR and/or nested PCR. The PCR assay targeting the 65 kDa protein gene could detect all of the tested mycobacterial strains, whereas targeting the IS6110 sequence resulted in detection of only M. tuberculosis and M. bovis BCG. Furthermore, targeting the mtp40 genomic fragment could be used to distinguish M. tuberculosis from M. bovis BCG. Using a nested PCR assay with primer sets specifically targeting the IS6110 or 65 kDa, we have been able to detect single copy M. tuberculosis genomic DNA. When the mtp40 genomic fragment was used as the target DNA, the sensitivity of detection was 10 copies of M. tuberculosis genomic DNA. This assay was demonstrated to have good sensitivity and specificity for detection and discrimination of mycobacterial species, and could be used in analyzing the clinical samples with low copy number infections such as the cerebrospinal fluid from the patient with tuberculous meningitis.

Bacterial Proteins↗
PubMed1999

Comparison of the sensitivity and specificity of an automatic ligase chain reaction assay system with a one-step polymerase chain reaction assay in the diagnosis of Mycobacterium tuberculosis complex.

BACKGROUND: Polymerase chain reaction (PCR) and ligase chain reaction (LCR) are two nucleic acid amplification-based molecular methods. The former has been used widely in the identification of Mycobacterium tuberculosis (M. tuberculosis). In contrast, the LCR assay which was recently introduced is not well known in our medical communities in Taiwan. To determine which method is more reliable and suitable for the identification of M. tuberculosis in our clinics, we compared the sensitivity and specificity of these two methods. METHODS: An automatic LCR assay system and a manual one-step PCR assay were studied in a side by side comparison of their performance in detection of M. tuberculosis. The automatic LCR system uses the single copy antigen protein b (Pab) gene and the manual one-step PCR assay uses the multi-copy IS6110 insertion element as the target DNA; both target DNA sequences are found specifically in M. tuberculosis complex. RESULTS: Both assays detected two of the M. tuberculosis complex strains, M. tuberculosis and M. bovis, but not other mycobacterial strains. In addition, both methods, which were based on different amplification principles, showed compatible sensitivity; as low as 10 and 100 copies of M. tuberculosis genomes were detected by the LCR and PCR assays, respectively. When the template DNA was less than 1000 copies, however, the automatic LCR assay system showed a lower reproducibility than that of the one-step PCR assay. CONCLUSION: Our results suggest that in addition to the PCR assay, the LCR assay is a useful method for the molecular identification of M. tuberculosis complex strains.

DNA Ligases↗
PubMed1999

Detection and identification of Mycobacterium tuberculosis by nested PCR assays in cerebrospinal fluid samples from patients with suspected tuberculous meningitis.

We used the nested polymerase chain reaction (PCR) assays developed previously to detect and identify Mycobacterium tuberculosis (M. tuberculosis) in the cerebrospinal fluid (CSF) samples from patients with suspected tuberculous meningitis and non-tuberculous patients. Our nested PCR assays target the multi-copy IS6110 insertion element and the single-copy mtp40 genomic DNA of M. tuberculosis. These assays, when used in combination, allowed us to detect a very low number of M. tuberculosis in the CSF samples, which otherwise would be undetectable by the culture method, and to distinguish M. tuberculosis from M. bovis. We applied these nested PCR assays to analyze eleven CSF samples. Among these, five of them were from patients with suspected tuberculous meningitis but all except one were culture negative. Our results of PCR assays show that three of these five are M. tuberculosis positive, one of which is M. bovis positive, and only one is M. tuberculosis negative. The other six CSF samples were from the clinically diagnosed non-tuberculous patients. Surprisingly, two of these so called non-tuberculous patients, a subarachnoid hemorrhage (SAH) and the syndrome of inappropriate antidiuretic hormone secretion (SIADH), were shown M. tuberculosis positive. This finding supports a long-standing argument that tuberculous meningitis is one of the causes of these neurological diseases. These nested PCR assays thus provide the neurologists with an important adjunct, in addition to the patient's clinical presentation and laboratory data, for the diagnosis of tuberculous meningitis.

Adolescent↗
PubMed1998

Reconstruction of scalp defects with free flaps in 30 cases.

29 consecutive patients treated for reconstruction of various scalp defects with 30 free flaps were reviewed. The scalp defects resulted from accidents (13), electric burns (4), tumour excision (8), chronic osteomyelitis (1), and osteoradionecrosis (1). Secondary reconstructions for cosmetic improvement were performed in 2 patients. The defects involved scalp with bone exposure in 21 patients, and both scalp and calvarium in 8 patients. The average extent of the defects was 130 cm2 (23-420 cm2). Free flaps employed for reconstruction included radial forearm flaps (15), latissimus dorsi muscle flaps (10), medial arm flaps (2), juri flap (1), rectus abdominis muscle flap (1), and scapular flap (1). In 6 cases bone grafts were used for skull reconstruction. Three patients required dura repair. There were two flap failures. Donor-site morbidity was negligible. No local recurrence occurred in 7 tumour cases who are still alive. Secondary procedures (tissue expansion, debulking) were performed in 6 patients. The authors recommend selection of reconstructive options for scalp defects according to their aetiology, localisation, and duration of treatment, whereas the size of the defect dose not seem to be the most important determinant. They conclude that a free flap procedure is appropriate for scalp reconstruction in trauma, osteomylitis, and osteoradionecrosis cases, and following radical resection of malignant tumours.

Accidents↗
PubMed1997

Digital tomosynthesis in breast imaging.

PURPOSE: To describe and evaluate a method of tomosynthesis breast imaging with a full-field digital mammographic system. MATERIALS AND METHODS: In this tomosynthesis method, low-radiation-dose images were acquired as the x-ray source was moved in an arc above the stationary breast and digital detector. A step-and-expose method of imaging was used. Breast tomosynthesis and conventional images of two imaging phantoms and four mastectomy specimens were obtained. Three experienced readers scored the relative lesion visibility, lesion margin visibility, and confidence in the classification of six lesions. RESULTS: Tomosynthesis image-reconstruction algorithms allow tomographic imaging of the entire breast from a single arc of the x-ray source and at a radiation dose comparable with that in single-view mammography. Except for images of a large mass in a fatty breast, the tomosynthesis images were superior to the conventional images. CONCLUSION: Digital mammographic systems make breast tomosynthesis possible. Tomosynthesis may improve the specificity of mammography with improved lesion margin visibility and may improve early breast cancer detection, especially in women with radiographically dense breasts.

Female↗
PubMed1995

The versatility of free rectus femoris muscle flap: an alternative flap.

In the 10-year period from June 1985 to December 1994, 54 free rectus femoris muscle or musculocutaneous flaps were performed at our hospital. It has been one of the most frequently used free muscle flaps in our institution and forms 2% of all free tissue transfers (total, 2,769 cases). In 26 patients, it was used for large wound coverage following debridement or tumor ablation, and in 27 patients, as a functioning free muscle transplantation for brachial plexus palsy or traumatic muscle loss. In one patient the components of the deep aponeurosis, muscle, and overlying skin were used for reconstruction of an abdominal wall defect after neurilemmoma excision. There were two complete failures, one due to diabetic foot infection and one due to venous occlusion. Four had superficial marginal skin necrosis. No significant disability of the donor limb was encountered. Easy approach, rapid harvest, large and reliable overlying skin flap, a single dominant neurovascular pedicle (with large vessel diameter and long motor nerve), easy primary closure of the donor site, and minimal donor site morbidity all make the rectus femoris flap a good alternative flap for free tissue transfer, in addition to the gracilis, rectus abdominis, and latissimus dorsi muscle flap.

Adult↗
PubMed1995

Adrenal cortical carcinoma with tumor thrombus invasion of inferior vena cava.

A case of adrenal cortical carcinoma with inferior vena cava (IVC) involvement is presented. Ultrasonography, computed tomography, and venacavography all presumptively showed a large mass over the upper pole of the left kidney with tumor thrombus in the IVC. However, aortography demonstrated that this mass was receiving its blood supply from the left inferior phrenic artery, aorta, and left renal artery. Radical surgery, including resection of the tumor and its adjacent organs (kidney, distal pancreas, spleen) and the tumor thrombus in the IVC, with the aid of cardiopulmonary bypass, was performed. We emphasize that adrenal cortical carcinoma can have tumor thrombi invading the IVC, and in such cases we suggest radical surgical removal of the tumor and the thrombus.

Adrenal Cortex Neoplasms↗
PubMedDate not supplied

Enzyme inhibitory assay using monoclonal antibody against acid alpha-D-glucosidase in prenatal diagnosis to identify homozygotes of Pompe's disease.

From January 1985 to January 1990, measurements of acid alpha-D-glucosidase activity in amniocytes or chorionic villus samplings were done for 24 pregnant mothers who were carriers of Pompe's disease. 6 women had two subsequent pregnancies. Amniotic fluid was obtained by transabdominal amniocentesis performed on 10 of them, while chorionic villus samplings were obtained in the other 20. The results showed that 7 (23.3%) cases were homozygotes, 16 (53.4%) cases were heterozygotes, and 7 (23.3%) cases were normal. Pregnancies were terminated in the homozygotic group. Final diagnosis was confirmed by either skin fibroblast culture or clinical course. However, we found that there was overlap in the acid alpha-D-glucosidase activity of amniocytes between homozygotes and heterozygotes due to residual activity of neutral alpha-D-glucosidase. In an attempt to identify heterozygotes for Pompe's disease, we established an enzyme inhibitory assay using monoclonal antibody (mAb) against acid alpha-D-glucosidase. Comparing the differences in alpha-D-glucosidase activity before and after mAb treatment the homozygotes were significantly lower than heterozygotes (P less than 0.001). There was no more overlap in the difference of acid alpha-D-glucosidase activity before and after mAb treatment between heterozygotes and homozygotes in amniocytes. This modified enzyme inhibitory assay should facilitate homozygote detection. Comparing acid alpha-D-glucosidase activity between CVS and amniocytes, the enzyme activity in CVS is about 5 times higher than in amniocytes. There was no overlap in the acid alpha-D-glucosidase activity between homozygotes and heterozygotes. Therefore, CVS is better than amniocentesis in the prenatal diagnosis of Pompe's disease.

Animals↗