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Biomedical subjects

M H Yang

Publications and source records attributed to M H Yang.

At least 55 records · Page 3Linked to original sources
PubMed1998

Expression of osteopontin and osteonectin in breast cancer.

Osteopontin (OP) and osteonectin (ON) are bone matrix proteins produced by mammary and other cancers. These proteins may play a role in tumor invasion and metastasis through integrin-mediated signal transduction. We evaluated expressions of OP and ON in 253 resected infiltrating ductal carcinoma of the breast, using immunohistochemical staining and follow-up data. OP and ON were detected 87.4% and 54.2% of 253 cases, respectively. The OP and ON positive staining were localized in the cytoplasm of carcinoma cells. OP and ON did not correlate with various clinicopathological parameters, such as age, lymph node involvement, tumor size, histologic grade, expression of p53 and estrogen receptor (ER). In the multivariate model, lymph node involvement and histologic grade were statistically significant prognostic factors. Assessed by a log rank test, the 5-year-survival rates of OP and ON positive groups and their negative groups were not statistically different. In conclusion, OP and ON immunopositivity of infiltrating ductal carcinomas of the breast provide no additional prognostic information in this study.

Adult↗
PubMed1998

Formaldehyde in the plant kingdom.

Formaldehyde, at its dimedone adduct, formaldemethone, has been detected by thin-layer and high-performance liquid chromatography in extracts of all species tested of marine algae, macrofungi, lichens, bryophytes, pteridophytes, gymnosperms and angiosperms. The yields of formaldehyde recorded in this study varied from 30 microg/g to 4060 microg/g, fresh weight.

Chromatography, High Pressure Liquid↗
PubMed1998

Pre-analytical for biological monitoring of manganese.

Manganese is an essential element but it may result in a toxic event if the workers are excessively exposed to this element. Monitoring of biological Mn exposure is therefore important. The careful preparation for Mn analysis is necessary. In order to get a correct protocol for sampling and storage of the biological samples, identification of the possible contamination source is necessary. This study is concerned with the monitoring procedure of manganese especially the sources of contamination sampling, sample transportation and storage. The results of the study shows that some kinds of needles and anticoagulants might be the main sources of contamination of specimen. It is important to avoid these contamination in performing biological monitoring on workers exposed to manganese.

Environmental Monitoring↗
PubMed1997

Automated on-line sample pretreatment system for the determination of trace metals in biological samples by inductively coupled plasma mass spectrometry.

A fully automated on-line sample pretreatment system combining microwave digestion with sample preconcentration/matrix separation for the determination of trace metals (Fe, Ni, Cu, Zn, and Pb) in blood and serum samples by inductively coupled plasma mass spectrometry (ICPMS) was designed and evaluated. The samples were mixed with an appropriate reagent and digested in a flow-through, focused microwave-heated oven. After digestion, the sample solution was transferred on-line to a column packed with iminodiacetate-based resin for separation of matrix elements like Na, K, Ca, Mg, Cl, P, and S that might interfere with the measurement by ICPMS. The analytes chelated on the resin were subsequently eluted and led to ICPMS for multielement determination. The whole sample pretreatment process was automatically controlled by a self-designed expert system. The analytical reliability of data from this on-line system was confirmed to be good with the analysis of SRM samples (Seronorm Whole Blood and NIST SRM 1598 Bovine Serum), and the limits of detection (3 sigma) for Fe, Ni, Cu, Zn, and Pb were 68, 0.34, 3.5, 13.4, and 0.22 microgram/L, respectively. With this fully automated on-line system, the determination of analytes in biological fluid samples down to micrograms-per-liter levels has been proven to be feasible, and the sample throughput can achieve up to 6 samples/h.

Animals↗
PubMed1997

Arsenic methylation capacity, body retention, and null genotypes of glutathione S-transferase M1 and T1 among current arsenic-exposed residents in Taiwan.

In order to elucidate the relationships among arsenic methylation capacity, body retention, and genetic polymorphisms of glutathione S-transferase (GST) M1 and T1, a total of 115 study subjects were recruited from Lanyang Basin located on the northeast coast of Taiwan. Specimens of drinking water, blood, urine, hair and toenail were collected from each study subject. Urinary inorganic and methylated arsenic were speciated by high performance liquid chromatography combined with hydride-generation atomic absorption spectrometry. Arsenic concentration in hair and toenail were quantitated by atomic absorption spectrophotometry. The polymerase chain reaction was used to determine genetic polymorphisms of GST M1 and T1. Arsenic concentrations in urine, hair, and toenail of study subjects were positively correlated with arsenic levels in their drinking water. Percentages of various arsenic species in urine (mean +/- standard error (SE) were 11.8 +/- 1.0, 26.9 +/- 1.2 and 61.3 +/- 1.4, respectively, for inorganic arsenic, monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA). Men and women had similar arsenic methylation capability. No associations were observed between arsenic methylation capability and arsenic content in either drinking water or urine. Ratios of arsenic contents in hair and toenail to urinary arsenic content (mean +/- standard error) were 6.2 +/- 0.7 and 16.5 +/- 1.7, respectively. Genetic polymorphisms of GST M1 and T1 were significantly associated with arsenic methylation. Subjects having the null genotype of GST M1 had an increased percentage of inorganic arsenic in urine, while those with null genotype of GST T1 had an elevated percentage of DMA in urine. Arsenic contents in hair and toenail were significantly correlated with the increase in arsenic concentrations of drinking water and urine, while no significant associations were observed between arsenic contents in hair and toenail and polymorphisms of GST M1 and T1. The relationship between arsenic methylation capability and body retention was modified by genetic polymorphisms of GST M1 and T1. Arsenic contents in hair and toenail were negatively associated with MMA percentage and positively associated with DMA percentage among subjects having null genotypes of GST M1 and T1, but not among those with non-null genotypes.

Arsenic↗
PubMed1997

Selective precipitation separation and inductively coupled plasma mass spectrometric determination of trace metal impurities in high purity silver.

A simple and rapid method for the determination of some trace element impurities in high purity silver, combining the isolation of analytes from the silver matrix with selective precipitation followed by ICP-MS determination was developed. On the basis of an extreme difference in the solubilities of the chlorides of silver and the other accompanying trace elements, silver can be separated completely through the addition of hydrochloric acid. The sample of silver was at first dissolved in 7 M nitric acid followed by addition of hydrochloric acid to remove the silver matrix by formation of a silver chloride precipitate, while leaving the trace element impurities in the solution, which was subsequently analysed by ICP-MS. Eleven elements (Al, Au, Cd, Co, Cu, Fe, Mg, Mn, Ni, Pb and Sn) were determined with good accuracy and precision. The limits of detection (based on the 3 sigma criterion) of these elements were 10(-1)-10(-3) ng g-1. The proposed method was successfully applied to the determination of metal impurities in high-purity silver samples (EM9465 and EM 9343) and validated by the analysis of NIST SRM 8171 (Fine Silver FS 14).

Chemical Precipitation↗
PubMed1997

Usefulness of argyrophilic nucleolar organizer regions score to differentiate suspicious malignancy in pulmonary cytology.

OBJECTIVE: Pulmonary cytologic specimens reported as "suspicious for malignancy" pose problems in clinical management. Silver staining for argyrophilic nucleolar organizer regions (AgNOR) has proved useful in making a cytopathologically differential diagnosis between benign and malignant cells. This study aimed to evaluate the usefulness of AgNOR score in the diagnosis of pulmonary cytologic specimens deemed inconclusive by conventional staining methods. METHODS: Pulmonary cytologic specimens initially reported as suspicious for malignancy with Papanicolaou or May-Grünwald-Giemsa (MGG) staining obtained from 35 proved cases were destained then restained using the AgNOR technique. Another 35 cases with clear cytologic diagnosis were also examined for comparison. The median number of dots, defined as the AgNOR score, was used to differentiate malignant from benign specimens. RESULTS: Malignant cases had significantly higher AgNOR scores than benign ones (p<0.001). There were no significant differences among smears previously stained with Papanicolaou or MGG method, among specimens obtained via bronchoscopic brushing, fine-needle aspiration of lung or pleural effusion, or among subgroups of malignant diseases. Based on the results of our previous study, the cutoff value of the AgNOR score to differentiate benignancy from malignancy was set at 6. At this setting, the sensitivity and specificity of AgNOR score were 88% and 80%, respectively, in aiding a differential diagnosis of pulmonary cytologic specimens initially classified as suspicious for malignancy. For those cases with a clear cytologic diagnosis, the sensitivity and specificity of AgNOR score were 92% and 100%, respectively. For all cases, the sensitivity of AgNOR score was 90% and the specificity was also 90%. CONCLUSIONS: The AgNOR score is of value in aiding a differential diagnosis between benign and malignant lesions in pulmonary specimens with equivocal cytologic features.

Artifacts↗
PubMed1997

The effect of cyclophosphamide on Fas-mediated apoptosis.

Fas is a cell surface protein that can mediate apoptosis and belongs to the tumor necrosis factor (TNF) receptor family. Anti-Fas antibody induces apoptotic cell death in sensitive cells. Because many chemotherapeutic drugs are capable of initiating pathways leading to apoptosis, we determined the effect of cyclophosphamide, one of the most widely used anticancer drugs, on Fas mediated apoptosis in human lymphoma cell lines; SKW6.4 and Jurkat. Cell lines were cultured for 3 days alone in a medium or with cyclophosphamide (2 micrograms/ml). Anti-Fas IgM of various concentrations was added after treatment. Apoptosis was measured by electrophoresis of DNA fragmentation and surface expression of Fas was measured by flow cytometry. These cell lines were found to express Fas and were very sensitive to anti-Fas induced by cyclophosphamide in Jurkat except SKW6.4. Cyclophosphamide augumented apoptosis mediated by anti-Fas, synergistically. These results suggested that the anti-cancer drug might be mediated via the pathway of Fas mediated apoptosis in the lymphoma cell lines.

Animals↗
PubMed1997

Pancreatic endocrine tumor admixed with a diffuse microcystic adenoma--a case report.

We report a case of pancreatic endocrine tumor admixed with a diffuse microcystic adenoma in a 67-year-old woman with a six months history of melena. Whipple's operation and near-total pancreatectomy were performed under the impression of a pancreatic cancer with duodenal invasion. The pancreas was enlarged and was entirely replaced by sponge-like tiny cysts, which were lined by a single layer of periodic acid Schiff positive cuboidal cells. Also encountered was a gray white solid area at the head portion which extended to the duodenum with an intraluminal polyp formation. The compact area was composed of solid and acinar structures of tumor cells, which showed a positive reaction for chromogranin A and neuron specific enolase, separated by delicate highly vascularized stroma. To the best of our knowledge, this is the first case report published with immunohistochemical studies to deal with a pancreatic endocrine tumor admixed with a diffuse microcystic adenoma.

Adenoma↗
PubMed1997

Extralobar pulmonary sequestration with an associated cyst of mixed bronchogenic and esophageal type--a case report.

We report an unusual case of extralobar pulmonary sequestration (ELS) with an associated cyst of mixed bronchogenic and esophageal type. A 58-year-old woman was incidentally found to have a 6 x 6 x 5 cm sized mass in the right superior mediastinum. The mass consisted of sequestrated pulmonary tissue and an unilocular cyst with a direct communication. The cyst could not be easily classified because it was lined by squamous or respiratory epithelium with two distinct muscle layers and bronchial glands. Bronchial cartilage was present in close proximity to the ELS. This unusual combination of ELS with a foregut cyst might be a part of bronchopulmonary foregut malformation, attributed to a common embryologic pathogenesis.

Bronchogenic Cyst↗
PubMed1997

Serum beta-carotene level, arsenic methylation capability, and incidence of skin cancer.

To elucidate the associations of arsenic-induced skin cancer with serum beta-carotene level and arsenic methylation capability, a total of 654 residents of age 30 or older were recruited from three arseniasis-hyperendemic villages in Taiwan and regularly examined for skin lesions during the follow-up period. There were 33 cases affected with newly diagnosed skin cancer during the follow-up, giving an incidence of 14.74 per 1000 person-years. Although most study subjects had stopped consuming high-arsenic artesian well water more than 20 years ago, the risk of skin cancer was found to increase significantly with cumulative arsenic exposure before the cessation of drinking artesian well water in a dose-response relationship. Frozen serum samples collected at the recruitment from newly developed skin cancer cases and matched controls were tested for beta-carotene levels by high-performance liquid chromatography. Frozen urine samples of these subjects were examined by high-performance liquid chromatography to speciate arsenite (AsIII), arsenate (AsV), monomethylarsonic acid (MMA), and dimethylarsinic acid and then quantitated by hydride generator combined with atomic absorption spectrometry. Skin cancer cases had a significantly lower serum level of beta-carotene than matched healthy controls. Although the primary methylation capability indexed by the ratio of MMA/(AsIII + AsV) was greater in cases than in controls, the secondary methylation capability indexed by the ratio of dimethylarsinic acid/MMA was lower in cases than in controls. An elevated proportion of MMA in total urinary arsenic level was associated with an increased risk of skin cancer. Subjects with a cumulative arsenic exposure of > or = 20.0 mg/liter-year and a proportion of MMA in total urinary arsenic level >26.7% had a multivariate-adjusted odds ratio of developing skin cancer as high as 20.91 (95% confidence interval, 2.63-166.5) compared wih those who had a cumulative arsenic exposure of <20.0 mg/liter-year and a MMA percentage of < or = 26.7%. Whether the association with capability of inorganic methylation is also applied to cancers of internal organs, including lung, liver, and urinary bladder, remains to be elucidated.

Adult↗
PubMed1996

Expression and mutation of H-ras in uterine cervical cancer.

In cervical cancer, abnormalities of ras genes have not been fully investigated. We studied the expression and mutation of H-ras oncogene in cervical cancer to investigate their relationship and usefulness as an independent prognostic indicator. Twenty-seven paraffin-embedded resection specimens of cervical cancer (21 squamous, 3 adeno, 2 adenosquamous, and 1 small cell) were examined by immunohistochemistry using a mAb H-ras p21 and by PCR and allele-specific oligonucleotide hybridization using H-ras codon 12 and 61 amplimers and oligonucleotide probes. A strong immunoreaction was noted in 10 cases (37%) and weak immunoreaction in an additional 6 cases (22%). H-ras codon 12 mutations were detected in 6 of 27 cases (22%) and all of the mutations were guanine to adenine transitions. There was no mutation in codon 61. Cases with codon 12 mutations included all 3 squamous, 2 adeno, and I adenosquamous carcinoma. Only 3 of 16 (19%) cases with positive staining and 3 of 11 (27%) cases with negative staining showed mutations. No correlation was found between ras gene alterations and patient survival time. Our findings indicate that expression and mutation of H-ras oncogene occur in cervical cancer but their determination adds no useful prognostic information.

Adult↗
PubMed1996

The impact of osteonectin for differential diagnosis of osteogenic bone tumors: an immunohistochemical and in situ hybridization approach.

Thirty-three osteosarcomas at various grades of histologic differentiation, including chondroblastic, osteoblastic, and fibroblastic variants, were investigated immunohistochemically for evidence of osteonectin. Twenty-two cases of varying types of osteosarcoma were examined with in situ hybridization for mRNA expression of osteonectin. Immunohistochemically, osteonectin was present in all the osteosarcomas in this study. With in situ hybridization, 12 out of 22 osteosarcomas showed a positive signal. Two osteochondrosarcomas, seven chondrosarcomas, and one mesenchymal chondrosarcoma were also studied with regard to the localization of osteonectin, either immunohistochemically or by in situ hybridization. Immunohistochemically, osteonectin was present in all the chondroid lesions except for one osteochondroma. However, in situ hybridization of osteonectin mRNA was negative in all the chondroid lesions we studied. This study revealed that immunohistochemical localization of osteonectin is not useful in providing conclusive diagnosis of osteosarcoma. In situ hybridization of osteonectin mRNA might be useful in differentiating osteosarcoma from nonsteogenic bone tumors.

Antisense Elements (Genetics)↗
PubMed1996

Myxoma of the mandible.

Myxoma of the jaw bone is a peculiar and rare tumor. A case of myxoma of the mandible is described in a 38-year-old man. The plain X-ray showed multiple osteolytic destructive lesions in the molar root area. CT scans demonstrated osteolytic expansile lesions with mild enhancement of the solid portion of the mass. Histologically, the tumor is composed of plump stellate cells with abundant amorphous myxoid stroma.

Adult↗
PubMed1996

Factors affecting DNA damage caused by lipid hydroperoxides and aldehydes.

Single (SSB) and double strand breaks (DSB) in supercoiled plasmid DNA pBR322 reacted with linoleic acid hydroperoxides (LOOH) were followed by agarose gel electrophoresis to obtain definitive information about factors affecting LOOH interaction with DNA. In water, LOOH induced extensive DSB, which were metal mediated and increased with incubation time. Adventitious metal bound to DNA was sufficient to decompose LOOH to reactive radicals, activity that was not readily inhibited by chelators DTPA and desferrioxamine. Added Fe2+ and Fe3+ increased SSB and DSB, although the effects of Fe2+ were more extensive. Above 100 microM both valences inhibited DNA damage. Strand breakage by LOOH proceeded via lipid alkoxyl and peroxyl radicals. Aldehydic lipid peroxidation products induced strand breaks via oxidation of double bonds, not by reactions of the carbonyl groups. Lipophilic antioxidants BHA, BHT, and alpha-tocopherol were about 20 times more effective than hydrophilic free radical scavengers sodium benzoate, inositol, DMSO, and mannitol in preventing LOOH-induced strand breaks, supporting lipid phase localization of the damage.

Aldehydes↗
PubMed1996

Effects of mixed leukocyte reaction, hydrocortisone and cyclosporine on expression of leukocyte adhesion molecules by endothelial and mesangial cells.

We investigated the effects of mixed leukocyte reaction (MLR), hydrocortisone (HC) and cyclosporine A (CsA) on the expression of leukocyte adhesion molecules on the mesangial (MC) and endothelial cells (EnC). Cell surface enzyme immunoassay showed that INFnu, IL-1beta, or TNF alpha stimulated expression of ICAM-1, or VCAM-1 on MC after 24 hours. Flow cytometric analysis demonstrated that MLR supernatant induced a marked increase in mean fluorescence of or % of cells highly expressing intercellular adhesion molecule(ICAM)-1 or vascular cell adhesion molecule (VCAM)-1 on both cells after 24 hours (p<0.001). HC treatment(300 ng/ml) during MLR effectively inhibited MLR-induced upregulation of ICAM-1 and VCAM-1 on both cells (p<0.005). When MLR supernatant with HC was added to adhesion molecule assay, there was no inhibitory effect of HC on VCAM-1. CsA treatment (500 ng/ml) during MLR caused a modest decrease in upregulation of VCAM-1 on EnC (p<0.05), but had no effects on ICAM-1 on both cells. CsA directly decreased expression of VCAM-1 on MC. In conclusion, alloreactive lymphocytes and monocytes upregulate the expression of VCAM-1 and ICAM-1 on target cells probably by the mediation of cytokines. HC effectively prevents MLR-induced upregulation of VCAM-1 and ICAM-1. CsA does not increase the expression of VCAM-1 and ICAM-1.

Cells, Cultured↗
PubMed1995

Well-differentiated, low-grade osteosarcoma of the clivus.

A case of well-differentiated osteosarcoma of the sphenoid bone was reported. The pathological differentiation of this rare entity from fibrous dysplasia, the radiographic appearance, and the differential diagnosis were discussed.

Diagnosis, Differential↗