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Biomedical subjects

Y C Yang

Publications and source records attributed to Y C Yang.

At least 19 recordsLinked to original sources
PubMed1999

Melatonin potentiates the GABA(A) receptor-mediated current in cultured chick spinal cord neurons.

The effect of melatonin on the gamma-aminobutyric acidA (GABA(A)) receptor-mediated response was studied in cultured chick spinal cord neurons using the whole-cell voltage-clamp recording technique. Melatonin rapidly and reversibly potentiated the GABA-induced current in a dose-dependent fashion, with an EC50 of 766 microM and a maximal potentiation of 148%. Potentiation of the GABA response by melatonin was mediated by increasing the potency of GABA rather than the efficacy. Prolonged exposure to a saturating concentration of the disulfide-reducing agent dithiothreitol did not attentuate the effect of melatonin on the GABA response, indicating that melatonin does not act through the redox site. Furthermore, our results demonstrate that melatonin and 5alpha-pregnan-3alpha-ol-20-one (a positive steroid modulator of the GABA(A) receptor) act through different sites.

Animals↗
PubMed1999

Distinct actions of interleukin-9 and interleukin-4 on a hematopoietic stem cell line, EMLC1.

EMLC1 is a hematopoietic stem cell line that depends on stem cell factor (SCF) for growth and generates lymphoid, erythroid and myeloid progenitors in the presence of different cytokines. We have studied signaling events leading to cell proliferation and differentiation of EMLC1 mediated by interleukin (IL)-4 and IL-9. It was found that IL-9 enhances SCF-induced cell proliferation and promotes erythropoietin (EPO)-dependent erythroid differentiation of EMLC1 cells. However, IL-9 alone cannot support the growth of this cell line. In contrast, IL-4 by itself is sufficient to promote the growth of EMLC1 cells, even in the absence of SCF. Antiphosphotyrosine immunoblots of total cell lysates demonstrated that IL-4 and IL-9 induce tyrosine phosphorylation of different cellular substrates. Both IL-4 and IL-9 stimulated tyrosine phosphorylation of SHP-2, whereas the 90-kD tyrosine phosphorylated protein induced by IL-9 stimulation is Stat3. We have also shown that IL-4 is much more potent than IL-9 in inducing the expression of primary response gene c-myc. It was further determined that c-myc antisense oligodeoxynucleotide blocked IL-4 supported cell growth. Taken together, these results indicate that IL-4 may serve as a growth-promoting factor for hematopoietic stem cells, and IL-9 enhances both growth and erythroid differentiation of primitive hematopoietic progenitors. The results also suggest that differences in tyrosine phosphorylation induced by IL-4 and IL-9 may in part determine their distinct biological functions.

Animals↗
PubMed1999

Human leukocyte antigen polymorphisms in the Taiwanese population.

Polymorphisms of human leukocyte antigens (HLA) are important in transplantation medicine, anthropologic studies, and paternity testing. We investigated the polymorphisms of HLA classes I and II in the Taiwanese population by means of serologic typing and polymerase chain reaction (PCR) analysis with sequence-specific primers. We calculated the HLA-A, -B, and -C gene frequencies in 673 Taiwanese subjects and the HLA-DRB1, and HLA-DQB1 gene frequencies in 204 subjects with available DNA samples. Haplotype frequencies and linkage-disequilibrium were analyzed on the basis of these data. The common HLA class I antigens were A11 (gene frequency, 34.9%), A2 (29.3%), A24 (15.8%), and A33 (9.8%); B60 (21.9%), B46 (13.1%), B58 (9.7%), and B13 (8.5%); and Cw1 (18.8%), Cw7 (15.3%), and Cw10 (10.7%). The common HLA-DRB1 and HLA-DQB1 alleles were DRB1*12 (15.2%), DRB1*09 (15.2%), DRB1*08 (12.0%), and DRB1*04 (12.0%); and DQB1*0301 (23.5%), DQB1*0303 (15.2%), DQB1*0601 (14.5%), and DQB1*02 (10.8%). The common two-locus haplotypes were A2-B46 (frequency, 9. 7%), A11-B60 (9.6%), and A33-B58 (6.8%); DRB1*09-DQB1*0303 (14.9%), DRB1*12-DQB1*0301 (14.2%), and DRB1*08-DQB1*0601 (10.7%). This study is the first to report the gene frequencies of HLA-DQB1 alleles and the common HLA-DR-DQ haplotypes among Taiwanese. Comparison of our results with those from two other Chinese populations in mainland China reveals that Taiwanese are more closely related to southern Han than to northern Han Chinese.

China↗
PubMed1999

Stroke complicating pregnancy and the puerperium.

BACKGROUND: The role of nonobstetric factors, such as stroke, in maternal mortality has become of increasing importance because maternal deaths resulting directly from obstetric causes are decreasing. Strokes contribute to high mortality and morbidity, and are severe complications during pregnancy and puerperium. The objective of this study was to investigate the maternal outcome of patients with complications of stroke during pregnancy and puerperium. The causes, incidence and essential management of stroke are also reviewed. METHODS: During the 10-year period from January, 1986, to January, 1996, women who suffered from stroke during pregnancy, or up to six weeks postpartum, and were discharged from our hospital were identified. Stroke was defined as the abrupt onset of a focal neurologic syndrome that consisted of hemorrhagic and ischemic central nervous system events. All were assessed using computerized tomography or magnetic resonance imaging. Neurologists reviewed each case from the medical records. RESULTS: Thirteen women who had had a stroke during pregnancy or puerperium were identified. Nine of these women had intracerebral hemorrhage and four had ischemic strokes. During this 10-year period, approximately 85,321 women gave birth at the Mackay Memorial Hospital, and the incidence of stroke was approximately 1 in 6,500 pregnancies. Among the nine cases of hemorrhagic strokes, three women had preeclampsia and one had gestational diabetes mellitus. Mortality from strokes was 38%, and 63% of survivors had residual neurologic deficits; 46% of the strokes occurred during the puerperium. CONCLUSIONS: Stroke during pregnancy and puerperium causes high mortality and morbidity. Early diagnosis and adequate treatment cannot be overemphasized, as prompt and proper management is beneficial for outcome. The same meticulous care provided during the antepartum and intrapartum periods should be continued into the puerperium.

Adult↗
PubMed1998

MRG1, the product of a melanocyte-specific gene related gene, is a cytokine-inducible transcription factor with transformation activity.

Identification of cytokine-inducible genes is imperative for determining the mechanisms of cytokine action. A cytokine-inducible gene, mrg1 [melanocyte-specific gene (msg1) related gene], was identified through mRNA differential display of interleukin (IL) 9-stimulated and unstimulated mouse helper T cells. In addition to IL-9, mrg1 can be induced by other cytokines and biological stimuli, including IL-1alpha, -2, -4, -6, and -11, granulocyte/macrophage colony-stimulating factor, interferon gamma, platelet-derived growth factor, insulin, serum, and lipopolysaccharide in diverse cell types. The induction of mrg1 by these stimuli appears to be transient, with induction kinetics similar to other primary response genes, implicating its role in diverse biological processes. Deletion or point mutations of either the Box1 motif (binds Janus kinase 1) or the signal transducer and activator of transcription 3 binding site-containing region within the intracellular domain of the IL-9 receptor ligand binding subunit abolished or greatly reduced mrg1 induction by IL-9, suggesting that the Janus kinase/signal transducer and activator of transcription signaling pathway is required for mrg1 induction, at least in response to IL-9. Transfection of mrg1 cDNA into TS1, an IL-9-dependent mouse T cell line, converted these cells to IL-9-independent growth through a nonautocrine mechanism. Overexpression of mrg1 in Rat1 cells resulted in loss of cell contact inhibition, anchorage-independent growth in soft agar, and tumor formation in nude mice, demonstrating that mrg1 is a transforming gene. MRG1 is a transcriptional activator and may represent a founding member of an additional family of transcription factors.

Animals↗
PubMed1998

Increased MAPK activity and MKP-1 overexpression in human gastric adenocarcinoma.

Mitogen-activated protein kinase (MAPK) has been known to play a critical role in the regulation of the carcinogenesis in human cancers. In an effort to understand the functional role of the MAPK in the carcinogenesis of human gastric tissues, we examined the changes of MAPK levels in human gastric adenocarcinoma. We found that increased MAPK activity was accompanied by overexpression of mitogen-activated protein kinase phosphatase-1 (MKP-1), suggesting that signaling pathways leading to the activation of MAPK and the induction of MKP-1 expression are associated with carcinogenesis of human gastric adenocarcinoma.

Adenocarcinoma↗
PubMed1998

Transforming growth factor-beta stimulates interleukin-11 transcription via complex activating protein-1-dependent pathways.

Studies were undertaken to characterize the mechanism by which transforming growth factor-beta1 (TGF-beta1) stimulates epithelial cell interleukin (IL)-11 production. Nuclear run-on studies demonstrated that TGF-beta1 is a potent stimulator of IL-11 gene transcription. TGF-beta1 also stimulated the luciferase activity in cells transfected with reporter gene constructs containing nucleotides -728 to +58 of the IL-11 promoter. Studies with progressive 5' deletion constructs and site-specific mutations demonstrated that this stimulation was dependent on 2 AP-1 sites between nucleotides -100 and -82 in the IL-11 promoter. Mobility shift assays demonstrated that TGF-beta1 stimulated AP-1 protein-DNA binding to both AP-1 sites. Supershift analysis demonstrated that JunD was the major moiety contributing to AP-1-DNA binding in unstimulated cells and that c-Jun-, Fra-1-, and Fra-2-DNA binding were increased whereas JunD-DNA binding was decreased in TGF-beta1-stimulated cells. The sequence in the IL-11 promoter that contains the AP-1 sites also conferred TGF-beta1 responsiveness, in a position-independent fashion, on a heterologous minimal promoter. Thus, TGF-beta1 stimulates IL-11 gene transcription via a complex AP-1-dependent pathway that is dependent on 2 AP-1 motifs between nucleotides -100 and -82 that function as an enhancer in the IL-11 promoter.

Base Sequence↗
PubMed1998

A population-based study of the prevalence and associated factors of diabetes mellitus in southern Taiwan.

Diabetes mellitus is one of the major health care problems in Taiwan, since the mortality rate has increased from 7.91 per 100,000 in 1980 to 35.1 per 100,000 in 1996. To determine the prevalence of diabetes in southern Taiwan and to investigate possible associated factors, a stratified systematic cluster sampling of 1638 subjects (780 men and 858 women) aged > or =20 years living in Tainan city was investigated with a standard 75-g oral glucose tolerance test. The crude prevalence of diabetes in Tainan was 9.0% (10.3% men and 7.9% women) and the age-adjusted prevalence was 9.2% (10.4% men and 8.1% women). The crude prevalence of IGT was 14.0% (13.8% men and 14.1% women), and the age-adjusted prevalence was 15.5% (15.0% men and 15.9% women). The prevalence of diabetes by using the revised new diagnostic criteria was 7.5%. The prevalence of diabetes and IGT increased significantly with age for both genders, although the rises in prevalence of IGT in women was less consistent. Diabetic and IGT subjects were older and had higher levels of BMI, triglyceride, systolic and diastolic blood pressure, and higher prevalence of obesity, hypertension, and dyslipidemia but indulged in less physical activity than non-diabetic subjects. The significant factors associated with the newly diagnosed diabetes were age, family history of DM, BMI, systolic blood pressure, physical activity, and serum triglyceride levels.

Adult↗
PubMed1998

Accuracy of frozen section diagnosis in gynecology.

OBJECTIVE: A retrospective study was undertaken to evaluate the accuracy of frozen section diagnosis in gynecological surgery. METHODS: We compared the results of 792 consecutive gynecological frozen section diagnoses with their final diagnoses from January 1991 to June 1996. Slides for which the frozen section diagnosis was uncertain or incompatible with the final diagnosis were reviewed by an attending pathologist to determine the possible causes. RESULTS: A total of 299 ovarian, 390 lymph node, 56 uterine lesions, and 77 other tissue samples were obtained. The frozen section diagnosis was compatible with the final diagnosis in 97.5% of cases. The sensitivity for nonbenign lesions was 90.9%, and the specificity was 99.5%. There were no false positives or overestimated cases; 1.3% of cases were falsely negative, 0.4% underestimated the degree of malignancy, and 0.9% were uncertain. Possible causes for incompatible or uncertain frozen section diagnoses were analyzed. The accuracy of frozen section diagnoses for ovarian, lymph node, uterine, and other tissues was also evaluated. Frozen section was found to identify correctly 13 of 17 ovarian malignancies metastaic from other organs, 14 of 15 germ cell malignancies, and 3 of 4 dysgerminomas. The low sensitivity in ovarian borderline malignancy was due to the even lower sensitivity in its mucinous subgroup. The relationship between section numbers and accuracy of frozen section diagnosis in mucinous ovarian tumors was assessed. CONCLUSIONS: Frozen section diagnosis in gynecology is sufficiently accurate for clinical use, with a low false negative rate and an even lower false positive rate. Most incompatible frozen section diagnoses occurred in ovarian lesions, especially in mucinous ovarian tumors. Performing multiple sections (at least one section for every 10 cm in diameter) is recommended in the frozen section diagnosis of mucinous ovarian tumors.

Female↗
PubMed1998

Vitreous loss during conversion from conventional extracapsular cataract extraction to phacoemulsification.

PURPOSE: To study the outcome of vitreous loss among senior surgeons converting from conventional extracapsular cataract extraction (ECCE) to phacoemulsification. SETTING: A university teaching hospital in the United Kingdom. METHODS: A retrospective analysis of 87 planned cataract extractions performed from January 1992 to December 1996 and complicated by vitreous loss was done. Outcome measures included postoperative complication rates and visual acuity. RESULTS: During the study, vitreous loss occurred in 39 patients having ECCE and in 48 having phacoemulsification; the latter group included 8 patients with dropped nucleus. Postoperative complications included cystoid macular edema (18.7% of phaco patients, 30.8% of ECCE patients), retinal detachment (2.1% of phaco patients, 5.1% of ECCE patients), and expulsive hemorrhage (5.1% of ECCE patients). Phaco patients had higher rates of postoperative corneal edema (27.1%) than ECCE patients (12.8%) and transient intraocular pressure elevation (33.3%) versus 20.5%) but were more likely to receive posterior chamber intraocular lenses (70.8% versus 35.9%; P = .0024, chi-square test). After excluding pre-existing diseases, 83.3% of phaco patients and 67.6% of ECCE patients achieved a visual acuity of 6/12 or better. CONCLUSIONS: With careful patient selection, experienced extracapsular surgeons converting to phacoemulsification can achieve favorable results even in the presence of complications such as vitreous loss or dropped nucleus.

Aged↗
PubMed1998

Mutations of K-ras oncogene in human adrenal tumours in Taiwan.

Recently, we have found a high frequency of p53 gene mutations in human functional adrenal tumours. As the tumorigenesis is a multigene defect, we believe that other oncogenes may also be involved in the initiation or progression of adrenal tumours. Using the single-strand conformational polymorphism (SSCP) method, we chose the ras oncogenes as the target in this screening procedure because their high mutation rates were detected in thyroid tumours. For the ras oncogenes analysed, exon 1 to exon 2 of H-ras and K-ras genes in the tumour tissues of 13 Conn's syndrome, two adrenal Cushing's syndrome, two non-functional adrenal tumours, one adrenocortical hyperplasia and eight phaeochromocytomas and its paired adjacent normal adrenal tissues were amplified and sequenced. No mutations were detected in the H-ras gene. But mutations of the K-ras gene were detected in 46% (6 of 13) of Conn's syndrome; the hot spots were located at codon 15, 16, 18 and 31, which were different from those previously found in other tumours (codon 12, 13 and 61). Northern blot analysis with 1.1 kb K-ras cDNA revealed that K-ras mRNA was more than tenfold over-expressed in four of Conn's syndrome, one case of Cushing's syndrome and one case of adrenocortical hyperplasia. The mutation sites and mutation type were not found in other tissues, which conferred that this was highly related to adrenocortical tumours. Yet, the correlation between K-ras oncogene and adrenocortical tumours needs to be clarified by further studies.

Adrenal Cortex Neoplasms↗
PubMed1998

Alterations of RET oncogene in human adrenal tumors.

Previous studies have revealed specific activations of the RET oncogene in multiple endocrine neoplasia type 2 (MEN 2) and thyroid tumors. To understand the role of the RET proto-oncogene activation in sporadic adrenal tumors, we analyzed the alterations of the RET proto-oncogene in the cysteine-rich extracellular domain (exons 6 and 10), the terminal region of the extracellular domain and transmembrane domain (exon 11) and the tyrosine kinase domain (exons 12-17) in 35 cases of adrenal tumors (including 18 Conn's syndrome, 3 Cushing's syndrome, 2 non-functional adrenocortical tumor and 12 pheochromocytomas by polymerase chain reaction-single strand conformational polymorphism and sequencing methods. One case with pheochromocytoma and one with Conn's syndrome had point mutation. We also detected the rearrangement of the RET gene by reverse transcription-polymerase chain reaction and Southern hybridization. One case with Conn's syndrome and one with Cushing's syndrome were found to harbor RET/PTC1 (RET tyrosine kinase domain rearranged with H4 gene). The above results indicate that RET proto-oncogene mutations and RET/PTC1 are involved in the pathogenesis of sporadic adrenal tumors. Mutations at codon 634 of the RET gene were also found in adrenal tumors. This suggests that the RET oncogene may also play a role in the tumorigenesis of adrenal tumors, and this possibility requires further investigation.

Adrenal Gland Neoplasms↗
PubMed1998

Fasting plasma glucose in screening for diabetes in the Taiwanese population.

OBJECTIVE: To reveal the relationship between fasting and 2-h postload plasma glucose and to examine the appropriate fasting glucose cutoff as the primary screening test for diabetes. RESEARCH DESIGN AND METHODS: We recruited 5,303 subjects from preventive services of the National Cheng Kung University Hospital. Exclusion criteria were age <20 years, pregnancy, known diabetes, and a history of recent surgery, trauma, or illness. All subjects received the 75-g oral glucose tolerance test. The relationship between fasting and 2-h glucose was examined. Sensitivities, specificities, efficiency, and predictive values were assessed at different cutoffs of fasting glucose for prediction of diabetes. RESULTS: The best fit model for the relationship between fasting and 2-h glucose was fasting glucose = 4.914-0.060 x (2-h glucose) + 0.0144 x (2-h glucose)2. From this model, the fasting glucose was 6.0 mmol/l when 2-h glucose was 11.1 mmol/l. A fasting glucose with 6.25 mmol/l gave the same diabetes prevalence as the World Health Organization 2-h glucose criterion. When 7.8 mmol/l was the fasting glucose cutoff, the sensitivity was 28.5%. Lowering the cutoff from 7.8 to 7.0 mmol/l increased the sensitivity by 11.2% and slightly reduced the specificity and positive predictive value. If the cutoffs were 6.25 and 6.0 mmol/l, the sensitivity increased and the specificity and the positive predictive value decreased accordingly. CONCLUSIONS: Our results suggest that fasting glucose as a screening criterion for diabetes could be revised downward to 7.0 mmol/l, because the slight reduction of positive predictive value was more than balanced by an apparent increase of sensitivity and insignificant change of specificity.

Adult↗
PubMed1998

Familial transmission of human T-lymphotropic virus type 1 (HTLV-1) in patients with adult T-cell leukemia/lymphoma or HTLV-1-associated myelopathy.

The seroprevalence of human T-lymphotropic virus type 1 (HTLV-1) in Taiwan is 0.48%. In this study, we investigated the patterns of intrafamilial transmission of HTLV-1 in Taiwanese patients with adult T-cell leukemia/lymphoma (ATL/L) or tropical spastic paraparesis/HTLV-1-associated myelopathy (TSP/HAM). Fifteen index patients (9 men, 6 women, aged 31-71 yr), 13 with ATL/L, and two with TSP/HAM, and 98 relatives were included. Of the 98 relatives, 23 were seropositive for HTLV-1. Spouses of 11 patients were studied. Seven of eight wives of male patients but none of the three husbands of female patients were HTLV-1 carriers. Mother-to-child transmission was found in seven of 13 families and in 15 of 75 children tested. The correlation of breast-feeding with seropositivity in two families with seropositive mothers indicates its important role in vertical transmission of HTLV-1. Our findings suggest that husband-to-wife and mother-to-child transmission are the main forms of intrafamilial transmission of HTLV-1 in Taiwan, a nonendemic area. Screening for HTLV-1 in family members of patients with ATL/L or TSP/HAM, and seropositive blood donors, may be warranted. Seropositive individuals should be educated to prevent the spread of the virus through sexual contact and breast feeding.

Adult↗
PubMed1998

Primary retroperitoneal liposarcoma mimicking ovarian cancer: a case report.

Primary retroperitoneal liposarcoma is a rare malignancy comprising about only 0.1% of all cancers. It produces nonspecific symptoms and is often extensive when diagnosed. In this report, we present a case of a 68-year-old female patient who had a 29-kg retroperitoneal liposarcoma. Her early symptoms--including vague digestive disturbances, increasing abdominal girth and an abdominal mass, and clinical examinations such as sonography and computed tomography scan led to a preoperative diagnosis of ovarian cancer, until surgical and pathologic confirmation. Gross, radical resection of the tumor was successfully performed, and provided the most effective primary therapeutic approach. Histopathology revealed a mixed-type liposarcoma, with metastasis to the appendix. A poor prognosis was expected. Postoperative periodic follow-up was started to monitor for early detection of recurrence.

Aged↗
PubMed1998

Well-differentiated papillary villoglandular adenocarcinoma of the uterine cervix: a case report.

In contrast to other types of cervical adenocarcinoma, well-differentiated papillary villoglandular adenocarcinoma of the uterine cervix is unique for its tendency to develop in young women and its excellent prognosis. Until now, no tumor recurrence has been reported in the English literature following surgical treatment that varies from conization to radical hysterectomy. We report a case of 47-year-old female who presented with postcoital bleeding and was treated by radical hysterectomy for FIGO (International Federation of Gynecologists and Obstetricians) Stage Ib cervical carcinoma, in which the preoperative cervical biopsy diagnosis was adenocarcinoma. The patient was well at follow-up nine months after surgery. A literature review including treatment implications is presented.

Biopsy↗
PubMed1998

High-grade endometrial stromal sarcoma in a 10-year-old girl: case report.

Endometrial stromal sarcomas occur primarily in perimenopausal women and are quite uncommon in children. We report a case of high-grade endometrial stromal sarcoma in a 10-year-old girl, who initially experienced lower abdominal pain on voiding. After a series of examinations, surgical treatment was performed, including an extended total hysterectomy with bilateral salpingo-oophorectomy, bilateral pelvic lymph node sampling, and partial omentectomy. Adjuvant radiotherapy and hormonal therapy followed, however, the abdominal tumor recurred 9 months later. Invasion of the right lobe of the liver with compression of the inferior vena cava and pleural effusion was noted. The patient then received prolonged oral etoposide therapy. The treatment stabilized the tumor size and relieved her symptoms for 4 months. She finally succumbed to the disease as a result of distant metastasis.

Child↗