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Biomedical subjects

S M Hsu

Publications and source records attributed to S M Hsu.

At least 37 records · Page 2Linked to original sources
PubMed1999

Breast cancer risk associated with genotype polymorphism of the estrogen-metabolizing genes CYP17, CYP1A1, and COMT: a multigenic study on cancer susceptibility.

Estrogen has been proposed to trigger breast cancer development via an initiating mechanism involving its metabolite, catechol estrogen (CE). To examine this hypothesis, we conducted a multigenic case-control study to determine whether polymorphisms of the genes responsible for CE formation via estrogen biosynthesis (CYP17) and hydroxylation (CYP1A1) and CE inactivation (COMT) are associated with an elevated risk for breast cancer in Taiwanese women, and whether the association between genotype and risk may be modified by estrogen exposure. One hundred and fifty breast cancer patients and 150 healthy controls were recruited. PCR-based RFLP assays were used to determine the genotypes of estrogen-metabolizing genes. The breast cancer risk associated with individual susceptibility genotypes varied among the three genes and was highest for COMT, followed by CYP1A1 and CYP17. After simultaneous consideration of all three genes and other well-established risk factors of breast cancer, the COMT genotype remained the most significant determinant for breast cancer development and was associated with a 4-fold increase in risk (95% confidence interval, 1.12-19.08). Furthermore, a trend of increasing risk for developing breast cancer was found in women harboring higher numbers of high-risk genotypes (P = 0.006), including the high activity CYP17 (CYP17 A2/A2), high inducibility CYP1A1 (CYP1A1 MspI vt/vt), and low activity COMT (COMT L/L) genotypes. The association of risk with the number of susceptibility genotypes was stronger in women with prolonged estrogen exposure (indicated by a higher number of estrogen exposure years or a higher number of estrogen exposure years between menarche and first full-term pregnancy), women with higher estrogen levels (implied by early menarche), and women with a higher body mass index (> or = 22.5). On the basis of comprehensive profiles of estrogen metabolism, this study supports the possibility that breast cancer can be initiated by estrogen exposure.

Body Mass Index↗
PubMed1999

Association between N-acetyltransferase 2 (NAT2) genetic polymorphism and development of breast cancer in post-menopausal Chinese women in Taiwan, an area of great increase in breast cancer incidence.

The incidence of breast cancer has increased greatly in Taiwan over the past 2 decades. Increased exposure to environmental carcinogens, including aryl aromatic amines, as a result of the economic boom, is suspected to be one factor contributing to this increase. The enzyme N-acetyltransferase 2 (NAT2) determines the rate of metabolism of aryl aromatic amines, and therefore the NAT2 slow acetylator genotype is associated with an increased risk of cancer. Our present case-control study of 150 breast cancer patients and 150 healthy controls in Taiwan was performed to explore the association between NAT2 genetic polymorphism and individual susceptibility to breast cancer. A structured questionnaire was used to collect relevant information regarding all known or suspected risk factors of breast cancer. The NAT2 genotype was determined using the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) assay in 139 cases and 133 controls, and 28.8% and 21.1%, respectively, were found to have slow acetylator genotypes. Multivariate analysis, simultaneously considering other risk factors, including age at menarche, nulliparity or age at first full-term pregnancy, body mass index (BMI), hormone replacement therapy (HRT) and smoking status, showed that the NAT2 slow acetylator genotype was associated with an increased risk with borderline significance (Odds Ratio, 1.81; 95% CI, 1.01-3.31). Interestingly, this association was not significant in premenopausal women, but was significant in post-menopausal women. Further stratification of our study subjects based on different risk factor status showed that the increased risk for an NAT2 slow acetylator was more marked in post-menopausal women who were not using HRT or who had a lower BMI. Our findings suggest that NAT2 polymorphism is a susceptibility factor for breast cancer in Taiwanese women, and that NAT2-metabolized carcinogens are probably present in the environment and may be associated with induction of breast cancer.

Acetylation↗
PubMed1999

Quiescent nasal T/NK cell lymphoma manifested as primary central nervous system lymphoma.

A 57-year-old man was diagnosed as primary T/NK-cell central nervous system lymphoma (CNSL) with intraocular involvement. However, review of a surgical specimen taken three years before for chronic paranasal sinusitis revealed an overlooked nasal T/NK cell lymphoma (TNKL), which showed similar histomorphology and immunophenotype with the CNS disease. Another patient, a 43-year-old woman, was initially diagnosed as a rare primary leptomeningeal T-cell lymphoma with ocular manifestation. Three years later, an isolated nasal TNKL emerged. Immunohistochemical and cytogenetic studies confirmed the same nature of the CNSL and the nasal TNKL. The nasal TNKLs of both patients had a strong expression of CD3, CD56, and Epstein-Barr virus antigens, but features of angiodestruction and mucosal ulceration were absent. We propose that: 1. a locally silent "quiescent" form of nasal TNKL may exist; and 2. a thorough examination and even blind biopsy of the nasal cavity is indicated when primary T/NK-cell CNSL is diagnosed.

Adult↗
PubMed1999

Using affinity capillary electrophoresis to evaluate average binding constant of 18-mer diphosphotyrosine peptide to antiphosphotyrosine Fab.

We used affinity electrophoresis in capillaries to investigate the interaction between a monovalent antiphosphotyrosine antibody fragment, antigen-binding fragment (Fab), and a divalent antigen (dAg), an 18-mer diphosphopeptide phosphorylated on two-site tyrosine residues. The migration shift behavior of Fab in electrophoretic solution was observed and the quantitative expression was presented to estimate the arithmetical average value of the intrinsic affinities for two epitopes on the dAg with the Ag binding site on the Fab. In dAg excess, based on measurement of mobility changes of Fab analytes at different dAg concentrations, the experimental average dissociation constant (Kd = 27.7 microM) was calculated. It was also found that the structural variation of the two epitopes for binding specificity to the Ag-binding domain of Fab is not apparent. Moreover, the Kd values of Fab-dAg complexes were measured at higher electric fields and shown to be independent of changes in the electric field. Thus, under conditions where the total dAg concentration is in excess of the total Fab concentration, the method and quantitative expression which we developed is generally useful for the understanding of molecular interaction for an unlabeled monovalent receptor and its divalent ligand in free solution.

Amino Acid Sequence↗
PubMed1999

The graded effect of hyperhomocysteinemia on the severity and extent of coronary atherosclerosis.

It is not clear to what extent methylenetetrahydrofolate reductase (MTHFR) gene and hyperhomocysteinemia effect the severity and extent of coronary atherosclerosis in Asian populations. We examined the MTHFR genotypes and plasma homocysteine (HCY) concentrations in 192 Taiwanese and investigated their relationship with coronary artery disease (CAD), and the severity and extent of coronary atherosclerosis. The distribution of MTHFR genotypes was similar in 116 CAD patients and 76 non-CAD subjects. Homozygosity was noted in 8% of CAD patients and 13% of non-CAD subjects (P=0.33; 95% CI, 0. 2-1.6). The geometric mean of HCY values was higher in CAD patients (11.10+/-1.51 micromol/l) than in non-CAD subjects (9.21+/-1.55 micromol/l) (P=0.003). HCY levels were higher in patients with multi-vessel disease (P<0.05) or in patients with > or = 90% stenotic lesions (P=0.005), compared with non-CAD subjects. The CAD risks in the top two HCY quartiles (> or = 14.0 and 10.1-13.9 micromol/l) were 4.0 (95% CI, 1.7-9.2) and 3.2 (95% CI, 1.4-7.4) times higher than in the lowest quartile (< or = 7.9 micromol/l) (P=0.001 and 0.007, respectively). Linear regression analysis showed significant correlations between HCY concentrations and the severity and extent of atherosclerosis (P=0.0001 for both). In conclusion, hyperhomocysteinemia appears to have a graded effect on the risk of CAD as well as the severity and extent of coronary atherosclerosis. Our findings do not support the homozygous genotype of MTHFR as a genetic risk factor for CAD in this Taiwanese population. Perhaps a further study including assessment of vitamin status is needed to better clarify the relationship between MTHFR genotypes and CAD.

Adult↗
PubMed1999

Cytochrome P4501A1 polymorphism as a susceptibility factor for breast cancer in postmenopausal Chinese women in Taiwan.

The incidence of breast cancer has been greatly increasing in Taiwan over the past two decades. Since cytochrome P4501A1 (CYP1A1) is involved in the metabolism of environmental carcinogens or oestrogen, we hypothesized that CYP1A1 genetic polymorphism may be a susceptibility factor for breast cancer. This hypothesis was evaluated in this case control study of 150 breast cancer patients and 150 healthy controls among Chinese women. Two CYP1A1 polymorphisms were studied, one containing a new Msp1 site and the other located in axon 7 and resulting in the replacement of an isoleucine (Ile) residue by a valine (Val). After simultaneously considering the known or significant risk factors for breast cancer, including the age of study participants, positive family history of breast cancer, early menarche (< or = 13 years), nulliparity and late first full-term pregnancy (> or = 30 years), hormone replacement therapy and smoking, the CYP1A1 Msp1 polymorphism was found to be a significant factor in determining the risk of breast cancer. The homozygous variant was the most susceptible genotype with an adjusted odds ratio of 1.98 (95% confidence interval (CI) = 1.01-3.99) compared with the non-homozygous variants (the homozygous wild-type and the heterozygous variant). In contrast, the CYP1A1 Ile/Val polymorphism was not significantly associated with breast cancer development (adjusted OR = 1.07, 95% CI = 0.64-1.78). Interestingly, the Msp1 polymorphism was especially significant in postmenopausal women, but not in premenopausal women. Further stratification analysis in postmenopausal women who were non-smokers and with no history of hormone replacement therapy showed the cancer risk due to the Msp1 variant to be more significant in women with early menarche. We conclude that CYP1A1 polymorphism is a susceptibility factor for breast cancer in postmenopausal Chinese women in Taiwan. Further study with a large sample size should be considered to address issues of interactions between CYP1A1 and other risk factors.

Amino Acid Substitution↗
PubMed1999

Microcalcifications of non-palpable breast lesions detected by ultrasonography: correlation with mammography and histopathology.

OBJECTIVES: Microcalcifications are generally not demonstrated well on ultrasonography. In this study, we attempted to demonstrate the usefulness of high-resolution ultrasonography in the detection of microcalcifications associated with non-palpable breast cancers. DESIGN: Fourteen patients with non-palpable breast lesions in whom microcalcifications were detected or suspected by ultrasonography and one patient in whom microcalcifications were detected on mammography only were included in the study. Mammography and analysis of biopsy specimens were performed in each patient and the findings were correlated with the ultrasonographic findings. Ultrasonography and mammography were performed independently by different physicians at different times. RESULTS: In three patients < or = 30 years of age, who were not at high risk of breast cancer and who had no evidence of cancer on palpation, high-resolution ultrasonography clearly showed microcalcifications but no mass. Two of these patients had ductal carcinoma in situ and one had small invasive carcinoma with extensive comedocarcinoma. Among the other 12 patients with non-palpable breast lesions, ultrasonography detected microcalcifications accurately in six and suggested possible microcalcifications in a further four. Microcalcifications in all of these ten patients were confirmed by mammography thereafter. Four of these ten patients had ductal carcinoma in situ, with or without invasive carcinoma. Of the remaining two patients, one demonstrated false-positive findings and one false-negative findings on ultrasound. On high-resolution ultrasonography, microcalcifications produced the appearance of twinkling stars (bright dots in different planes) in a dark sky (contrasted against ill-defined hypoechoic patches), corresponding on histopathology to groups of expanded ducts with increased cell density with or without necrosis. CONCLUSION: High-resolution ultrasonography may be used for detection of microcalcifications in non-palpable breast lesions. Ultrasonography is helpful in screening for early breast cancers, especially in young patients who are at risk for breast cancer and in whom mammography is not usually carried out.

Adult↗
PubMed1999

Tumor immunology--when a cancer cell meets the immune cells.

Tumor immunology consists of two essential concepts: immune surveillance, which specifies the host immune reactions against tumor cells, and tumor immune escape, which refers to the tumor-cell evasion process against the host immune system. Effective antitumor immunity by the host immune surveillance is supposed to be dependent on the identification of tumor antigens. In the process of malignant transformation, genetic mutations with aberrant expression of cancer-related genes and protein products are potentially immunogenic, which may serve as rejection antigens. Several scenarios are proposed to be responsible for tumor immune-escape mechanisms. The elucidation of the immune deficit against cancer progression has been a difficult task and no solitary mechanism explains the complicated cancer-host immune interactions. Cancer cells may overcome immune surveillance through a common but effective pathway, either by changing the polarity of effector cells, thus down-regulating the proliferation of tumor-specific cytotoxic T cells, or altering the effector compositions of immune cells within the tumor milieu, or both. Understanding the interaction between cancer cells and host immune cells within the tumor milieu is of importance for further clinical applications of immunotherapy in cancer treatment.

Antigens, Neoplasm↗
PubMed1998

Abundance of heat shock proteins (hsp89, hsp60, and hsp27) in malignant cells of Hodgkin's disease.

Heat shock proteins (HSPs) or stress proteins are synthesized by cells in response to environmental stress. Expression of HSPs by cells may have important physiological or pathological implications. In this study, we carried out an immunohistochemical and biochemical examination of low (hsp27), intermediate (hsp60), and high (hsp89) molecular weight HSP expression in reactive lymph nodes and in lymph nodes of patients with various types of lymphomas. In normal or reactive lymphoid tissues, hsp89 is abundant in large "transformed" lymphoid cells and immunoblasts. Hsp60 is widely distributed in lymphoid tissues, whereas hsp27 is absent in all lymphoid cells and histiocytes. Among lymphomas, the Hodgkin's Reed-Sternberg (H-RS) cells in Hodgkin's disease (HD) had the greatest abundance of hsp89 and hsp60 and, in 20% of cases, hsp27, in contrast to a much weaker staining of anti-hsp89 and -hsp60 in the background reactive lymphoid cells. The large lymphoid cells in small lymphocytic lymphoma are also rich in hsp89, but not hsp60 and hsp27. In contrast, the malignant cells in anaplastic large cell lymphoma and most high-grade tumors, including immunoblastic lymphomas, expressed minimal amounts of hsp89 and hsp60 and virtually no hsp27. Thus, the cellular level of HSPs was neither correlated with the proliferative capacity nor with the aggressiveness of the lymphomas. Hsp89, hsp60, and hsp27, as well, serve critical roles in the chaperoning of cellular proteins (e.g., a Mr 43,000 protein) in H-RS cells. The known interactions of HSPs with Rb, p53, peptide-MHC class II complexes, and cofactors of the glucocorticoid hormone receptor have further broadened the importance of HSPs in cell metabolism and in response to extracellular signals for proliferation, differentiation, or growth suppression (or apoptosis) of H-RS cells. Abundant HSP expression is seen only in HD, but not in other lymphomas. Such expression could have vital roles in the pathogenesis of HD.

Actins↗
PubMed1997

Determination of the dissociation constant of phosvitin-anti-phosphoserine interaction by affinity capillary electrophoresis.

We used affinity capillary electrophoresis (ACE) to study the interaction of a monoclonal anti-phosphoserine antibody (mAb) to a homopolyvalent antigen (hpAg), phosvitin. A model system, which allows the measurement of the true dissociation constant (Kd) in Ag excess based on measurement of migration shifts of mAb-hpAg complexes at different Ag concentrations in solution, is presented for the study of the interactions between a mAb and an Ag that has identical determinants. The experimental value of Kd (22.4 x 10(-6) M) obtained by ACE is shown to be in close agreement with the value (17.8 x 10(-6) M) obtained by the conventional immunoassay based on indirect competition enzyme-linked immunosorbent assay (ELISA). Moreover, the Kds of mAb-hpAg complexes were measured and shown to be independent of the applied electrical field strength. Thus, under conditions where the total Ag concentration is in large excess over the total Ab concentration and when certain requirements are fulfilled, this method offers the advantage of dealing with the determination of Kd for unlabeled mAb and homopolymeric Ag molecules in free solution rather than at the liquid-solid interface.

Antibodies, Monoclonal↗
PubMed1997

Determination of the association constant for slow phosphoserine-anti-phosphoserine interaction kinetics by capillary zone electrophoresis.

Capillary zone electrophoresis (CZE) was used to study the interaction of a monoclonal anti-phosphoserine antibody with its antigen. A model system that allows the determination of the real binding constant in a solution based on the change in peak areas at different concentrations of phosphoserine has been used for studying slow monoclonal antibody-antigen interaction kinetics involving low-molecular-weight antigens. CZE was applied in preincubation experiments. The slow interaction kinetics led to band broadening and resulted in far lower efficiency of the separation of complexed antibody from unbound antibody. However, when the run-to-run reproducibility of free phosphoserine was examined, it was found that it can be recovered quantitatively under electrophoresis conditions. On the basis of measurement of peak areas at different phosphoserine concentrations, the association constant was estimated (Ka = 5.21 X 10[5] M[-1]) and shown to be in close agreement with that obtained by equilibrium dialysis (Ka = 4.65 X 10[5] M[-1]). As long as the antigen participating in the interaction can be detected and recovered quantitatively in the CZE system, the method is generally useful for the study of monoclonal antibody-antigen interaction where the kinetics is slow and where the charge/ mass ratio of the unbound antigen differs from that of the complexed molecule.

Animals↗
PubMed1997

In situ DNA fragmentation assay for detection of apoptosis in paraffin-embedded tissue sections. Technical considerations.

Detection, by light microscopy, of cells in situ undergoing apoptosis has been improved by use of an in situ apoptosis (DNA fragmentation) assay on formalin-fixed and paraffin-embedded tissue sections. We studied conditions of tissue preparation and fixation that may affect the test results. In this study, we intended to determine whether archival tissues prepared under unknown conditions can be used for the in situ apoptosis assay. All tissue sections were pretreated with Proteinase K, followed by incubation with biotinylated 11-deoxyuridine triphosphate in terminal deoxynucleotidyl transferase and then avidin-biotin-peroxidase complex. The following formalin-fixed and paraffin-embedded histologic sections were tested: (1) normal tissues from surgically resected specimens fixed immediately or stored at 4 degrees C and then fixed after 1, 2, 4, 6, or 24 hours; (2) archival autopsy material from histologically normal tissues; and (3) freshly prepared normal tissues from C57 mice. We observed that fixation- and prefixation-elapsed times do not adversely affect the results of the assay. Similar, if not identical results were seen in archival human tissues stored for up to 25 years, the normal tissues freshly prepared from surgical specimens, and the tissues from C57 mice. We conclude that the in situ assay of DNA fragmentation is rapid, sensitive, and reproducible. The use of formalin-fixed and paraffin-embedded archival material as old as 25 years opens the way for a variety of studies of apoptosis in diverse pathologic states.

Animals↗
PubMed1996

Absence of T-cell- and B-cell-specific transcription factors TCF-1, GATA-3, and BSAP in Hodgkin's Reed-Sternberg cells.

Based on the presence of T cell receptor-beta (TcR-beta) gene rearrangements in L428 and HDLM-1 cells, the expression of CD2 in HDLM-1 cells, and the presence of immunoglobulin heavy-chain (IgH) gene rearrangement in KM-H2 cells, some researchers have concluded that these long-term cell lines derived from patients with Hodgkin's disease are lymphoid in nature. The information obtained from these cell lines has also been used in arguments for a lymphoid origin of H-RS cells in tissue despite the frequent absence of lymphoid markers and Ig/TcR gene rearrangements in these cells. We questioned whether one can use the limited expression of lymphoid markers or the limited gene rearrangement to conclude that H-RS cells have a lymphoid origin, because these markers may be aberrant in tumor cells. In this study, we examined the expression of two T-cell-specific transcription factors (TCF-1 and GATA-3) and one B-cell-specific transcription factor (BSAP) in cultured H-RS cells by using a gel mobility shift assay. The sensitivity and specificity of this assay for determination of cell lineage have been established in a large number of cultured human and murine cell lines. All three types of H-RS cell lines were consistently negative for BSAP, TCF-1, and GATA-3. The absence of GATA-3 was confirmed in H-RS cells in tissues by an in situ hybridization technique. Virtually all B-cell lines, with the exception of some myeloma cell lines, are positive for BSAP, which is the transcription factor for promoters for several B-cell markers, including VpreB1, lambda 5, CD19, and CD20. All T-cell lines tested were positive for TCF-1 and GATA-3, which are the transcription factors for promoters for several T-cell-restricted markers, including CD2, CD3, TcR, and lck. The absence of BSAP, TCF-1, and GATA-3 clearly indicates an underlying difference between H-RS cells and lymphoid cells.

Alzheimer Disease↗
PubMed1996

In situ apoptosis assay for the detection of early acute myocardial infarction.

Detection and age determination of myocardial infarction (MI) is often necessary in both clinical and pathological settings. Conventional histopathological techniques are of limited utility in the demonstration of myocardial ischemic cell death (MICD) within the first 6 hours of MI. In this study, an in situ apoptosis assay was evaluated for the determination of early MICD or early MI. Sections of formalin-fixed, paraffin-embedded archival tissue blocks from 80 hearts were stained for the presence of apoptotic cells by specific labeling of nuclear DNA fragmentation. Conventional hematoxylin and eosin stain showed acute MI (group A, n = 32), equivocal evidence for MICD or early infarction (group B, n = 35), or no abnormal findings (group C, n = 13). The sensitivity and specificity of the in situ apoptosis assay for MICD were confirmed in groups A and C patients. We showed that apoptosis of myocardial cells can occur after ischemic myocardial cell injury. Virtually all documented cases of acute MI (group A) revealed a sizeable distribution of apoptotic cells visible on gross examination of glass slides. Special attention was given to patients in group B, who were at high risk for MI and for suspected but not proved cardiac death. In this group, 34/35 cases (97%) showed focal or diffuse nuclear positivity of varying degrees for apoptosis, confirming the presence of MICD. A sizeable distribution of apoptotic cells, similar to that observed in group A, was noted in 13/35 cases (37%) of group B, suggesting acute MI in these cases. The in situ assay of DNA fragmentation can detect MICD while the histological diagnosis is still inconclusive. It is estimated that with this assay one can detect MICD as early as 2 to 4 hours.

Adult↗
PubMed1996

Apoptosis is a major pathway responsible for the resolution of type II pneumocytes in acute lung injury.

Proliferation of type II pneumocytes has been linked to a repair process during the early phase of acute lung injury, and it persists for a variable period. The mechanisms responsible for their dissolution and/or disappearance are not known, but we speculate that it may be partly due to apoptosis. Sections of lung tissue from patients with acute lung injury (n = 7) and chronic interstitial pneumonia (n = 14) were stained for detection of apoptotic cells via specific labeling of nuclear DNA fragmentation. Results were correlated with those of proliferating cell nuclear antigen (PCNA) staining for cell proliferation. Marked apoptosis of CD68-negative type II pneumocytes (30 to 80%) was detected in four of the seven (57%) cases of acute lung injury. In these cases, representing the resolution phase of acute lung injury, PCNA positivity in pneumocytes was extremely rare. In the 3 other cases in the acute/proliferative phase, apoptotic type II pneumocytes were rare whereas PCNA expression was quite evident in these cells. In chronic interstitial pneumonia, only rare type II pneumocytes (< 5%) exhibited apoptosis, and they showed variable staining for PCNA (up to 70%). We conclude that proliferation of type II pneumocytes occurs during the early phase of acute lung injury and is of variable extent and duration. In the resolution phase of acute lung injury, extensive apoptosis of type II pneumocytes is largely responsible for the disappearance of these cells. The time frame within which the apoptotic response occurs is variable and is likely to be dependent upon the specific etiology and extent of the injury. In chronic interstitial pneumonia, type II pneumocytes proliferate continuously, although to a much lesser degree than in the early phase of acute lung injury, and are minimally apoptotic.

Acute Disease↗