Biomedical subjects

Y C Yang

Publications and source records attributed to Y C Yang.

At least 55 records · Page 3Linked to original sources

PubMed2000

Identification of a lexA gene in, and construction of a lexA mutant of, Xanthomonas campestris pv. citri.

The lexA gene of Xanthomonas campestris pathovar citri (X.c. pv. citri) was cloned and sequenced. The 639-bp open reading frame encodes a protein of 213 amino acids that shares substantial sequence homology with the products of previously characterized lexA genes, sharing 46% identity with the LexA protein of Escherichia coli. Amino acids required for autocatalytic cleavage of LexA are conserved in the X.c. pv. citri protein, whereas domains thought to mediate DNA binding differ markedly from those of LexA proteins from E. coli and other bacteria. The X.c. pv. citri LexA protein was overexpressed in E. coli, and SDS-polyacrylamide gel electrophoresis revealed a molecular size of 23 kDa for the purified protein. A lexA mutant of X.c. pv. citri was constructed by gene replacement, and the basal level of recA expression in this mutant was shown to be similar to that for wild-type cells exposed to a DNA-damaging agent. These results indicate that LexA functions as a repressor of recA expression in X.c. pv. citri.

Bacterial Proteins↗

PubMed2000

Biaxial residual stress states of plasma-sprayed hydroxyapatite coatings on titanium alloy substrate.

Biaxial residual stress states of plasma-sprayed hydroxyapatite coatings (HACs) on titanium alloy substrate as a function of plasma power, powder feed rate and coating thickness were studied by X-ray 'sin2 psi' method. The Young's modulus of hydroxyapatite (HA), required for the stress analysis, was measured from the separated free coating by three-point bending test method. It was found that the directions of principal stresses were in proximity to and perpendicular to the spraying direction. The measured Young's moduli of HACs were much lower than the theoretical value reported. The denser, well-melted HAC exhibited a higher residual stress, as compared with the less dense, poor-melting HAC. The denser coatings could be effected by higher plasma power and lower powder feed rate. Significantly, the thicker 200 microm HAC exhibited higher residual stress than that of the thinner 50 microm HAC. The implications of residual stress in HAC for biomaterials are discussed in detail.

Alloys↗

PubMed2000

Epidemiologic study of type 2 diabetes in Taiwan.

Diabetes mellitus (DM) in adults is a global health problem, although its prevalence varies widely between different populations and the rate has generally increased worldwide. In Taiwan, the mortality rate from DM has almost doubled over the past 10 years. The prevalence of DM in Taiwan was established between 1985 and 1996 and the rates were between 4.9 and 9.2%. The prevalence of impaired glucose tolerance (IGT) was 15.5% (men 15% and women 15.9%). The prevalence of DM and IGT increased significantly with age for both genders. The significant factors associated with newly diagnosed DM were age, BMI, family history of DM, systolic blood pressure (hypertension), physical activity and serum triglyceride levels. The prevalence of large vessel disease (LVD) in DM and non-diabetic subjects were 20.0 and 12.9%, respectively. Among diabetics, 15.8% had ischemic heart disease (IHD), 1.7% leg vessel disease (leg VD), and 2.5% stroke. In non-diabetics, the prevalence of the aforementioned macroangiopathies were 11.5, 0.2 and 1.2%, respectively. The diabetics had a significantly higher prevalence of macrovascular disease than non-diabetic subjects. The most significantly associated with the LVD was serum cholesterol levels. Serum cholesterol and HbA1(c) were significantly associated with the development of IHD. Cigarette smoking and female gender were significantly associated with the leg VD. The prevalence of diabetic retinopathy (DR) was 35.0%. (background DR 30%, preproliferative DR 2.8% and proliferative DR 2.2%, respectively.) The prevalence of DR for previously and newly diagnosed diabetics were 45.2 and 28.3% (men 42.8 vs. 33.3% and women 47.5 vs. 24.8%), respectively. From multiple logistic regression analysis, duration of DM was the most important risk factor related to DR. Diabetic subjects treated with insulin had a higher risk of developing retinopathy than those treated with dietary control. The prevalence of nephropathy and neuropathy were 12.9 and 23.5%, respectively. For those patients with and those without nephropathy and neuropathy, the duration of DM, percentage of insulin treatment, percentage of hypertension, and fasting plasma glucose were significantly different. Diabetic duration, hypertension, insulin treatment and glycemic control consistently correlated with nephropathy and neuropathy. In conclusion, the prevalence of DM in Taiwan was between 4.9 and 9.2%, and the prevalence of IGT was 15.5%. The possible risk factors of newly diagnosed diabetes were age, family history of DM, BMI, SBP (hypertension), physical activity and triglyceride levels. Diabetes in Chinese subjects share many characteristics similar to other Asian populations. The burden imposed by the chronic complications of diabetes is massive. In Taiwan, the mortality rates from DM have increased greatly over the past 10 years. Reduction of the modificable risk factors such as BMI, hypertenion and dyslipidemia, and increase of physical activity and good glycemic control through public health efforts may help to reduce the risk of DM and its chronic complications.

Adult↗

PubMed2000

Neurotoxin 6-aminonicotinamide affects levels of soluble proteins and enzyme activities in various tissues of golden hamsters.

The effects of neurotoxin 6-aminonicotinamide (6-AN) on the levels of soluble proteins and enzyme activities in various tissues of golden hamsters were investigated. SDS-polyacrylamide gel electrophoresis showed that a soluble spinal cord protein with molecular mass 75.0 kDa was present at a higher concentration in the treated group compared to that in the control while that of a molecular mass 64.8 kDa appeared to be missing. However, there were no noticeable differences in protein concentrations observed with the cerebrum, brain stem, and cerebellum. Similarly, treatment with 6-AN decreased the concentration of a soluble protein in pectoral muscle having molecular mass 97.2 kDa and increased those having molecular masses 207.4 and 32.1 kDa. In the kidney, soluble proteins with molecular masses 176.6 kDa was missing and those of molecular masses 97.6, 49, 43.3, and 33.8 kDa were decreased whereas those of molecular masses 64.7 and 33.1 kDa were increased. In the testis the soluble proteins with molecular masses 125.4, 88.7, 69.0, 31.2, 19.1, and 17.4 kDa were missing and those of molecular masses 97.0, 51.3, 42.0, 33.0, 27.2, and 22.6 kDa were present in lower amounts whereas those of molecular masses 311.5, 75.0, 64.0, 54.1, and 53.2 kDa were present in higher amounts. The specific activity of 6-phosphogluconate dehydrogenase was markedly increased in the liver but that of other tissues was not affected. Acetylcholinesterase activity was markedly reduced in the spleen but was enhanced in the intestine. Monoamine oxidase activity was markedly reduced in the brain stem, cerebrum, kidney, and liver. The results suggest that the changes in levels of soluble proteins and enzyme activities shown with golden hamster tissues by 6-AN administration were quite different from those shown with quail tissues.

6-Aminonicotinamide↗

PubMed2000

Polyoxygenated bipyridine, pyrrolylpyridine, and bipyrrole alkaloids from Speranskia tuberculata.

Five novel polyoxygenated alkaloids, speranculatines A-C (3-5), speranskilatine A (6), and speranberculatine A (7), have been isolated from Speranskia tuberculata. Compounds 3-5, 6, and 7, have bipyridine, pyrrolylpyridine, and bipyrrole skeletons, respectively. This is the first time that these three alkaloid structural types have been reported. The structures of 3-7 were elucidated by spectroscopic methods, including 2D NMR techniques and X-ray crystallographic analysis.

Alkaloids↗

PubMed2000

Relationships of age, menopause and central obesity on cardiovascular disease risk factors in Chinese women.

OBJECTIVE: To evaluate the inter-relationships of age- and menopause- related changes of general obesity and body fat distribution and their independent effects on cardiovascular risk factors. DESIGN: Cross-sectional study. SUBJECTS: One-hundred and thirty-six premenopausal and 193 postmenopausal Chinese women with body mass index (BMI) < 30 kg/m2. MEASUREMENTS: Anthropometric surrogates of general obesity (BMI, total body fat percentage) and central obesity (waist-to-hip ratio, centrality index) were measured. Blood pressure, 75 g oral glucose tolerance test, glycosylated hemoglobin A1c and lipid profiles were also measured. RESULTS: Significant correlation coefficients between age, general obesity, central obesity and cardiovascular disease risk factors were noted. Through the menopausal transition, the BMI and total body fat percentage were increased significantly. After adjustments for age and BMI, the postmenopausal women showed higher android fat percentage, centrality index, glycosylated hemoglobin A1c, serum concentrations of total cholesterol, low-density lipoprotein (LDL) cholesterol and atherogenic indices than the premenopausal women. In multiple stepwise regression models, age exerted independent effects on oral glucose tolerance test 2 h plasma glucose level, systolic and diastolic blood pressure, total cholesterol level, and LDL cholesterol. Menopause was an independent variable in relation to the changes of glycosylated hemoglobin A1c, total and LDL cholesterol levels, triglyceride levels and atherogenic indices. The centrality index was the major independent variable of all the cardiovascular disease risk factors, except total and LDL cholesterol level. However, the variation of total body fat percentage had no independent effect on any cardiovascular disease risk factors. CONCLUSION: Through the aging and menopausal effects, women will increase total body fat content, favoring the central body fat distribution. Age, menopause and central obesity were all independent and significant factors to the cardiovascular disease risk factors in Chinese women.

Adipose Tissue↗

PubMed2000

Adenoid basal carcinomas of the cervix: a unique morphological evolution with cell cycle correlates.

Adenoid basal carcinoma (ABC) is a rare cervical carcinoma of postmenopausal women composed of small basal-type (basaloid) cells with focal endocervical ("adenoid") differentiation. ABCs are associated with high-grade squamous intraepithelial lesions (HSIL) and contain integrated human papillomavirus type 16 DNA. However, ABCs have a favorable prognosis and do not metastasize. Five (5) ABCs were analyzed histologically for a marker distinguishing basal/ squamous from columnar (adenoid) differentiation (p63) and cell cycle activity (Ki-67), and compared with 20 cervical (CC) carcinomas. In contrast to other CCs, ABCs contained 4 distinct components, including (1) a classic HSIL; (2) a limited invasive component with squamoid maturation, often with a discrete layer of peripheral basal cells; (3) outgrowth of small basal cells from either HSIL or squamoid areas; (4) focal endocervical (adenoid) differentiation. ABCs showed distinct differences in cell cycle activity relative to CCs. Ki-67 positivity was high in associated HSILs but remained high and concentrated in the suprabasal cells of the invasive squamoid component of ABC. Moreover, proliferative index was variable to sharply reduced in areas of basaloid and adenoid differentiation, in contrast to conventional CCs. ABC is a unique neoplasm, not only by its transition through multiple phenotypes during invasion, but also by a proliferative index that is high in more mature neoplastic cells during the infiltrative process and reduced with progressive basal differentiation. The precise mechanism underlying this unique process of tumor evolution is unclear. However, the postmenopausal status of these patients suggests that host factors related to aging may influence tumor evolution and morphology after HPV 16 infection.

Basal Cell Carcinoma↗

PubMed2000

Hypertension in elderly persons: its prevalence and associated cardiovascular risk factors in Tainan City, southern Taiwan.

BACKGROUND: Hypertension was the eighth leading cause of death in Taiwan in 1996, and the prevalence of hypertension has increased recently. The purpose of the study was to assess the prevalence of hypertension and its associated cardiovascular risk factors in elderly persons in Tainan City, southern Taiwan. METHODS: The study was a cross-sectional, population-based study. We used the stratified cluster sampling method to enroll subjects aged 65 years and above, 1435 persons in total, into our study. Questionnaire interview, body weight, body height, and blood pressure measurement were completed for 876 participants (response rate of 70.2%) at each subject's home by home visit. RESULTS: Hypertension was defined according to the criteria of the Fifth Report of the Joint National Committee on Detection, Evaluation, and Treatment of High Blood Pressure. The crude prevalence of hypertension was 60.4% (men 59.1%, women 61.9%); previously diagnosed hypertension was 31.1% (men 29.4%, women 33.1%); and newly diagnosed hypertension was 29.3% (men 29.7%, women 28.8%). The hypertensive group had a higher body mass index (BMI) than the normotensive group. There were no lifestyle differences such as smoking, drinking, eating a vegetarian diet, reading health information, and undergoing a health examination in the past year between the hypertensive and normotensive groups. However, the hypertensive group had a higher prevalence of regular exercise than did the normal blood pressure group on univariate analysis. Only BMI and family history of hypertension had a significantly positive association with hypertension on multiple logistic regression analysis. CONCLUSIONS: The crude prevalence of hypertension was 60.4% in elderly persons in Tainan City. Subjects who had family history of hypertension and higher BMI had a higher risk of hypertension, so they should be screened for high blood pressure regularly.

Age Factors↗

PubMed2000

Successful treatment of recurrent pelvic desmoid tumour with tamoxifen: case report.

The case report of a young woman with recurrent pelvic desmoid tumour successfully treated with tamoxifen is described. The desmoid tumour recurred within 6 months after the initial exploratory laparotomy. Tamoxifen therapy led to complete relief of ascites within 2 months and complete tumour regression by the end of the fourth month, and the patient has remained stable for 6 years. Without sacrificing pelvic organs or major vessels and preserving reproductive ability, tamoxifen should be considered as the first drug of choice in such a recurrent condition.

Adult↗

PubMed2000

Progesterone receptor gene expression in preimplantation pig embryos.

OBJECTIVE: It is not known whether progesterone, which plays a key role in establishing and maintaining pregnancy, acts directly on embryos or indirectly through the mother's reproductive tract. Since the physiological effects of progesterone are mediated by progesterone receptors (PR), the expression of PR during the preimplantation stages of pig embryos was determined. DESIGN AND METHODS: Preimplantation pig embryos at different developmental stages were examined using reverse transcription-polymerase chain reaction techniques for the purpose of determining PR gene expression. Immunocytochemistry procedures were used to determine whether PR mRNA is translated into PR protein in preimplantation embryos. RESULTS: PR mRNA was found in pig embryos at the two-cell stage, but levels started to decline at the four-cell stage; none was detected at the five- to eight-cell stage, nor at any time during the morula and blastocyst stages. Results showed that PR protein was immunostained in pig oocytes and embryos at the 4-cell stage, but that no significant immunostaining occurred during the morula and blastocyst stages. CONCLUSION: These results indicate that the effects of PR on early embryogenesis appear to be indirect, perhaps via PR-regulated growth-promoting factors produced in the maternal reproductive tract.

Animals↗

PubMed2000

Successful management of massive blood loss to extremely low hemoglobin in an elderly woman receiving spinal surgery.

Blood transfusion is absolutely indicated in acute anemia when the hemoglobin concentration falls below 6 g/dL. Sometimes it challenges the anesthesiologists if the blood intended for urgent transfusion is not readily or quickly available. In this case report, we describe an 81-year-old lady who accidentally sustained acute anemia after spinal surgery with the hemoglobin concentration falling to 1.4 g/dL. During the long wait for the process of cross-matching tests and delivery of blood from the blood bank in the city remote from the hospital, we could do nothing but administer crystalloid and colloid solutions to maintain the circulatory volume to prevent low cardiac output. Epinephrine was given when systolic blood pressure fell below 70 mmHg. Central venous pressure and arterial blood pressure were monitored to guide all the treatment. Fortunately, patient fully recovered on postoperative day 3 without any adverse events.

Aged↗

PubMed2000

Intraocular pressure and pulse rate measurements by the OBF tonograph--comparison to reference instruments.

The purpose of this study was to evaluate the accuracy of intraocular pressure (IOP) and ocular pulse rate (OPR) measurements obtained by the Ocular Blood Flow (OBF) tonograph (OBF Labs, Wiltshire, UK). Measurements of IOP and OPR by the OBF tonograph were compared to those of reference instruments. For IOP evaluation, measurements were obtained on patients with normal and abnormal pressures using the OBF tonograph and the Goldmann applannation tonometer in random alternate order. For the OPR evaluation, measurements were obtained using the OBF tonograph with simultaneous heart rate monitoring by ECG on patients with normal IOP. The validity of the OBF tonograph measurements was quantified in terms of 95% limits of agreement and their relationships to measurements by reference instruments was determined by linear regression analyses. 102 patients were recruited for IOP measurements. Mean IOP obtained by the Goldmann tonometer was 20.7 mmHg (7-42 mmHg, SD 6.98) whilst mean IOP obtained by the OBF tonograph was 20.1 mmHg (8.1-40.2, SD 6.1). Goldmann IOP and OBF tonograph IOP readings were well correlated (r = 0.945). Analysis of the difference in IOP measurements between two instruments (tonograph minus Goldmann tonometer) showed the mean bias to be 0.26 mmHg (-7.8 to +6.1 mmHg) and the 95% limits of agreement to be -4.35 to +4.87 mmHg. Agreement between two instruments appeared to be dependent on the IOP; at IOP lower than 20.6 mmHg there was an overall tendency for the tonograph IOP to be higher than Goldmann IOP and vice versa when IOP was above 20.6 mmHg. 47 patients were recruited for OPR and ECG measurements. Mean pulse rates were 74.8 beats per min (mean 43-110) by ECG and 73.9 beats per min (43-110) by tonography. Analysis of the difference in pulse rate between instruments (tonograph OPR minus ECG pulse rate) against the average pulse rate showed the mean bias to be -0.8 beats and the 95% limits of agreement to be between -7 to +5 beats. Ocular pulse rate values obtained by the OBF tonograph were very accurate when compared to ECG pulse rate. This indicates that there is unlikely to be a systematic lag in continuous ocular pulse waveform recording. Intraocular pressure measurements by the OBF tonograph correlated very well with Goldmann readings over a wide range of pressures and should be valid in the clinical setting.

Heart Rate↗

PubMed2000

[Surveillance of filariasis in some vulnerable areas in Guangxi after filariasis elimination].

OBJECTIVE: To explore the measures for continuing surveillance of filariasis. METHODS: Selecting some vulnerable spots for focal surveillance, double-slide biood sampling for microfilaria examination, dissecting vectors for detecting the mosquitoes infected with filarial larva, using IFAT for detecting antifilarial antibody. RESULTS: 27,938 persons were examined for microfilaria and 4,454 mosquitoes were dissected for filaria larva, all were negative. 3,606 serum samples were examined for antifilarial antibody average positive rate was 1.35%(0.39-4.97%). CONCLUSION: The results of surveillance showed that the achievement of filariasis control in Guangxi after filariasis elimination is consolidated.

Animals↗

PubMed1999

Tip60 interacts with human interleukin-9 receptor alpha-chain.

Interleukin-9 (IL-9) exerts its pleiotropic effects through the IL-9 receptor (IL-9R) complex that consists of the ligand specific IL-9R alpha-chain, and the IL-2R gamma-chain. In this study, we used a modified yeast two-hybrid system to isolate cDNAs encoding proteins that interact with the intracellular domain of the human IL-9R alpha-chain (hIL-9Ralpha). We have identified Tip60, an HIV-1 Tat transcription cofactor, as an hIL-9Ralpha interacting protein. The interaction between hIL-9Ralpha and Tip60 was confirmed by coimmunoprecipitation and colocalization studies. This is the first demonstration that Tip60 associates with a membrane receptor. We also mapped amino acids 411-423 in hIL-9Ralpha and amino acids 100-147 in Tip60 to be important for interaction. Interestingly, the region in hIL-9alpha that binds Tip60 is adjacent to the site previously shown to interact with Stat3. Tip60 binds HIV-Tat and mediates Tat-dependent transactivation possibly through its histone acetyltransferase activity. Our results therefore suggest that Tip60 may act as a cofactor of Stat3 or as an adaptor protein for molecules that are important for IL-9 signaling.

Acetyltransferases↗

PubMed1999

Postural hypotension and postural dizziness in patients with non-insulin-dependent diabetes.

BACKGROUND: Postural hypotension with a decline of 20 mm Hg or more in systolic blood pressure on standing is considered a potentially dangerous hypotensive response. Postural dizziness is often strongly associated with postural hypotension. However, there is conflicting evidence, and previous studies have been confined to the elderly, not specifically to patients with diabetes. Thus, we evaluated the association between postural hypotension and postural dizziness, and determined the factors most likely related to postural hypotension in patients with diabetes. METHODS: The subjects were 204 consecutive noninsulin-dependent patients with diabetes and 408 age- and sex-matched control subjects. Postural hypotension was defined as a decline of 20 mm Hg or more in systolic blood pressure 1 minute after standing. Postural dizziness was any feelings of dizziness, lightheadedness, or faintness that occurred while standing during the examination. RESULTS: The prevalence of postural hypotension and postural dizziness in patients with diabetes was higher than in control subjects. Those patients with both diabetes and postural hypotension were older and had higher supine systolic blood pressures and higher plasma glycosylated hemoglobin and fasting glucose levels. They had higher prevalence of postural dizziness, hypertension, and cerebrovascular disease, and lower standing systolic blood pressures than those without postural hypotension. They also were more often being treated with antihypertensive agents. Only 32.8% of patients with diabetes with postural hypotension suffered from postural dizziness. Postural dizziness, hypertension, cerebrovascular disease, and plasma glycosylated hemoglobin levels were independently associated with postural hypotension in patients with diabetes. CONCLUSIONS: Postural dizziness, glycemic control, hypertension, and cerebrovascular disease were important determinants of postural hypotension in patients with diabetes. Postural hypotension was associated with postural dizziness, but it cannot be determined clinically just from the presence of postural dizziness because the sensitivity for diagnosis of postural hypotension is low.

Aged↗

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

Modified radical hysterectomy for early Ib cervical cancer.

A total of 39 patients with selected early Ib cervical cancer were treated with modified radical hysterectomy (MRH) and compared with 102 patients with nonbulky Ib cervical cancer treated with radical hysterectomy (RH). Postoperative voiding difficulty (15.4 vs 46%) and constipation (43.6 vs 74.5%) were significantly less after MRH than after RH. All patients with MRH were followed uneventfully and the 3-year survival rate is 100%. No recurrence or persistence of disease was noted. It is suggested that patients with exophytic squamous cell carcinoma of the cervix less than 2 cm in diameter and invading less than 10 mm, as diagnosed by conization, may be effectively treated with MRH, resulting in less morbidity.

Female↗

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↗