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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
PubMed2006

Joint association of polymorphism of the FGFR4 gene and mutation TP53 gene with bladder cancer prognosis.

The impact of the fibroblast growth factor receptor 4 (FGFR4) Gly388Arg polymorphism on bladder cancer is unknown. We found no clear correlations between the FGFR4 genotype and risk of bladder cancer or pathological parameters. Neither the polymorphism nor TP53 mutation status was an independent predictor of prognosis, but they might act jointly on the disease-specific survival of patients.

Aged↗
PubMed2006

Negative effect of heat sterilization on the free amino acid concentrations in infant formula.

Infant formulas are often heat sterilized in hospitals where water contamination or nosocomial infection is a concern, but there are few studies of the effect of high heat on the nutritional value of infant formula. In particular, the effect of heat sterilization on free amino acid (FAA) concentrations is seldom discussed. In view of the importance of these nutrients for infant growth, we investigated the FAA concentrations of infant formula after heat sterilization. Powdered infant formulas were reconstituted with hot water (80 degrees C) in glass bottles and placed in an autoclave for 5 min at 105 degrees C and 5600 kg/m2 of pressure. Additional samples of formula were prepared by conventional methods to serve as controls. After autoclaving, we measured the FAA concentrations with ion exchange chromatography. The results were compared with those obtained after conventional preparation. We found a 19.5% lower amount of total protein after autoclaving compared with conventional preparation. Concentrations of total FAA were significantly lower after autoclaving (696.5 +/- 101.4 vs 899.4 +/- 152.2 micromol/l, P = 0.01). The concentrations of individual amino acids were also lower in autoclaved infant formulas, with differences ranging from -4.1 to 71.5% (mean 22.6%). Concentrations of certain amino acids were more than 30% lower, such as valine (71.5%), citrulline (61.1%), glutamine (60.6%), ethanolamine (54%), and lysine (39.2%). Both essential and nonessential amino acids were similarly affected by autoclaving, 28.17 and 27.13%, respectively, lower than in controls (P = 0.37). The concentration of ammonia was significantly higher after autoclaving (645.2 +/- 76.2 vs 393.2 +/-140.7 micromol/l, P = 0.0003). However, the urea level was significantly lower after autoclaving than after conventional preparation (1110.8 +/- 162.7 vs 1426.5 +/- 209.5 micromol/l, P = 0.0004). The accumulation of ammonia may reflect degradation of protein and amino acids. Autoclaving clearly results in decreased concentrations of FAA in infant formula. The increased concentration of ammonia after autoclaving is of concern if it leads to deleterious effects.

Amino Acids↗
PubMed2006

Late-onset visual decline following successful treatment of subfoveal choroidal neovascularisation with photodynamic therapy.

Photodynamic therapy (PDT) has been shown in large studies to be capable of achieving closure of choroidal neovascularization (CNV), thereby resulting in stabilization of visual acuity. We report a series of four patients with classic CNV treated with PDT with good initial result but subsequent severe visual loss that may be related to a change in the morphology of the subretinal scar.

Choroidal Neovascularization↗
PubMed2005

Verteporfin photodynamic therapy of choroidal neovascularization in angioid streaks: one-year results of a prospective case series.

PURPOSE: To report the 12-month results on the use of verteporfin photodynamic therapy (PDT) in the treatment of choroidal neovascularization (CNV) secondary to angioid streaks. STUDY DESIGN: Five-center prospective case series. METHODS: Patients with CNV secondary to angioid streaks who were treated with PDT were recruited and followed up at 3-month intervals for 12 months, with the addition of visits at 1.5 and 4.5 months if deemed appropriate by the investigator. Best-corrected visual acuity (BCVA) was measured at each visit after full refraction or with their current distance spectacles using Early Treatment Diabetic Retinopathy Study logarithm of the minimum angle of resolution charts. Stereoscopic fundus fluorescein angiography was used to determine baseline lesion characteristics and location. RESULTS: Twenty-two patients were recruited (23 eyes, 16 with subfoveal CNV and 7 with juxtafoveal; all classic no occult). Seventeen patients (77%) had angioid streaks secondary to pseudoxanthoma elasticum. In the subfoveal group, median BCVA at baseline was 49 letters (approximate Snellen equivalent, 20/100) and was 46 at 12 months (approximate Snellen equivalent, 20/125). Twelve of 16 eyes (75%) lost fewer than 8 letters, whereas 14 of 16 eyes (88%) lost fewer than 15 letters. The mean CNV greatest linear dimension (GLD) was 2520 microm at baseline. At 12 months, 7 of 16 eyes with subfoveal CNV at baseline were leaking (GLD = 3220 microm; P = 0.62). The mean number of treatments in the first 12 months was 2.9. In the juxtafoveal group, the median BCVA at baseline was 66 letters (approximate Snellen equivalent, 20/50) and was 51 letters at 12 months (approximate Snellen equivalent, 20/100). Two of 7 eyes (29%) gained 8 or more letters at the 12-month examination, whereas 4 of 7 eyes (57%) lost more than 15 letters. The mean CNV GLD at baseline was 1890 microm. At 12 months, 1 of 7 eyes with juxtafoveal CNV at baseline was leaking. Choroidal neovascularization progressed from juxtafoveal to subfoveal location during the follow-up period in 4 of 7 eyes. The mean number of treatments in the first 12 months was 3.4. No side effects were noted in either patient group. CONCLUSIONS: This small series suggests that treatment of CNV secondary to angioid streaks with verteporfin PDT seems to limit visual loss in most patients through the first 12 months of follow-up, particularly in those with subfoveal lesions at baseline.

Adult↗
PubMed2005

MHC class I chain-related gene A (MICA) polymorphism and the different histological types of cervical cancer.

Cervical cancer has been one of the most important gynecologic cancer in Taiwan with incidence of 24/100,000 and mortality of 8.7/100,000 annually. About 70-80% are squamous cell carcinoma; the remainder are composed of various types of adenocarcinoma, adenosquamous carcinoma and undifferentiated carcinoma. The Major Histocompatibility Complex (MHC) class I chain-related gene A (MICA) is expressed by keratinocytes and epithelial cells and interacts with gamma-delta T cells. Although MICA was not associated with cervical cancer in the study of Northern Sweden, there are no further studies about the association of MICA polymorphism and the different histological types of cervical cancer. We analyzed the MICA polymorphism in 110 cervical cancer cases (88 squamous cell carcinoma, 12 adenocarcinoma and 10 adenosquamous carcinoma) and 82 randomly selected unrelated controls from 1994 to 2000 in the Mackay Memorial Hospital, Taipei, Taiwan. DNA was extracted part from leukocytes of peripheral blood, part from tumor tissue and 5 polymorphic microsatellite alleles (A4,A5,A5.1,A6,A9) of MICA were identified by a polymerase chain reaction-based (PCR) technique using ABI Prism 377-18 DNA sequencer (Applied Biosystems, Foster City, CA, USA). The phenotypes, alleles and genotypes of MICA gene were calculated. There was no association with cervical cancer patients and non-cervical cancer patients (p=0.337, 0.356 and 0.414). After dividing the cervical cancer patients into 3 major histological types (squamous cell carcinoma, adenocarcinoma and adenosquamous carcinoma), the result was still the same (p=0.598, 0.172 and 0.617) in our study. We found no association between MICA gene polymorphism and cervical cancer in Taiwan. Different histological types of cervical cancer also have no significant correlation with MICA gene polymorphism. It demonstrates that polymorphism of MICA gene bears no relation to cervical cancer and the different histological types of cervical cancer in Taiwan. We need further studies for identifying the factors causing the differentiation of cancer cells of the uterine cervix.

Adenocarcinoma↗
PubMed2004

Imaging cells and tissues with refractive index radiology.

Can individual cells, including live cells, be imaged using hard x rays? Common wisdom until now required sophisticated staining techniques for this task. We show instead that individual cells and cell details can be detected in culture solution and tissues with no staining and no other contrast-enhancing preparation. The sample examined can be much thicker than for many other microscopy techniques without sacrificing the capability to resolve cells. The key factor in our approach is the use of a coherent synchrotron source and of contrast mechanisms based on the refractive index. The first successful tests were conducted on a variety of cell systems including skin and internal leaf cells, mouse neurons, rabbit fibroblast cells, and human tumor cells.

Animals↗
PubMed2004

Eye nutrient products for age-related macular degeneration: what do they contain?

BACKGROUND AND PURPOSE: Patients are increasingly well informed about the availability of antioxidant products and the claims made for their benefits in age-related macular degeneration (AMD). Consequently, their use is becoming widespread. The purpose of this study is to conduct a survey of the commonly encountered products, and to compare their ingredients with the current Age-Related Eye Disease Study (AREDS) recommendations. METHODS: A search was undertaken for products sold as 'eye nutrients' at local pharmacies and health food shops, and for products advertised via the Internet. Information about these products was collated and analysed. RESULTS: We identified 22 eye nutrient products. Analysis of their constituents showed that, although over 75% contained all the constituents used in AREDS, only two matched the dosage profiles recommended in the study. CONCLUSION: The authors draw no conclusion on the efficacy of nutritional supplements in the prevention of AMD. In order to advise their patients, ophthalmologists should be familiar with these products. The compiled list in this paper should provide a useful reference for them.

Antioxidants↗
PubMed2003

Mechanical properties and Young's modulus of plasma-sprayed hydroxyapatite coating on Ti substrate in simulated body fluid.

This study evaluated the Young's modulus, residual stress and strain, bonding strength, and microstructure of the plasma-sprayed hydroxyapatite coating (HAC) on Ti6Al4V substrate with and without immersion in Hank's balanced salt solution (HBSS). The purpose was to explore the possible correlation of HAC durability and mechanical properties of the coating. The results show that the residual stress and strain, Young's modulus, and bonding strength of the HAC after immersion in HBSS are substantially decreased. The decayed Young's modulus and mechanical properties of HACs are accounted for by the degraded interlamellar or cohesive bonding in the coating due to the increased porosity after immersion that weakens the bonding strength of coating and substrate system. The biologic implications of the research are discussed in detail. This study contributes to the arguments that the method to alleviate the dissolution of HAC will increase the bonding strength of the coating system after immersion, which together with the controlled residual stress and strain in the coating might promote the long-term stability of the HA-coated implant.

Adhesiveness↗
PubMed2003

Measurements of linear dimensions on fundus photographs: comparison between photographic film and digital systems.

PURPOSE: The aim of this study is to compare linear fundal landmarks measurements of standard photographic film with colour digital fundal images. METHODS: Pairs of fundus fluorescein images were acquired with a digital system and photographic film on 10 patients. Each pair of images was assessed independently by two observers who calculated the distance between two selected points on each image using easily identifiable landmarks. Measurements made using film images were compared to measurements made using the corresponding digital images. Agreement between the two methods of measurements was assessed using a linear correlation and graphical method. RESULTS: The patients were divided into two groups based on the field setting on the digital software. In Group 1, the correlation coefficient was 0.99 and in Group 2 it was 0.98, indicating a high level of agreement between measurements with the computer measuring tool for digital images compared to photographic films using a standard reticule. CONCLUSION: On the basis of the strong correlation between linear fundal landmark measurements between standard photographic film and colour digital fundal images, we conclude that the measurements from the digital images are acceptable for diagnostic and therapeutic purposes. Although there was a tendency for the measurements to be less accurate with increasing distances measured.

Fluorescein Angiography↗
PubMed2003

Successful treatment with weekly paclitaxel in a patient with recurrent endometrial cancer. A case report.

The best treatment for recurrent endometrial cancer is still uncertain, although weekly paclitaxel has shown some promise in the management of this disease. In this report we present a patient with recurrent endometrial cancer treated with weekly paclitaxel. Serial power Doppler angiography was used to assess the effects of therapy. The response was good, suggesting that recurrent endometrial cancer may be successfully treated with weekly paclitaxel and effectively monitored with power Doppler angiography.

Adenocarcinoma↗
PubMed2001

Hormonal markers and hepatitis B virus-related hepatocellular carcinoma risk: a nested case-control study among men.

BACKGROUND: The incidence of hepatitis B virus (HBV)-related hepatocellular carcinoma (HCC) is higher in men than in women. We examined whether endogenous sex hormone levels or hormone-related factors might affect the risk of HCC in men. METHODS: Baseline blood samples were collected from 4841 male Taiwanese HBV carriers without diagnosed HCC from 1988 through 1992. Plasma testosterone and estradiol levels and genetic polymorphisms in the hormone-related factors cytochrome P450c17 alpha (CYP17, A1 versus A2 alleles), steroid 5 alpha-reductase type II (SRD5A2, valine [V] versus leucine [L] alleles), and androgen receptor (AR, number of CAG repeats) were assayed among 119 case patients who were diagnosed with HCC during 12 years of follow-up and 238 control subjects. All statistical tests were two-sided. RESULTS: The risk of HCC increased with increasing concentrations of testosterone (odds ratio [OR](highest versus lowest tertile) = 2.97; 95% confidence interval [CI] = 1.54 to 5.70; P(trend) <.001) and with increasing number of the V allele of the SRD5A2 V89L polymorphism (OR(VV versus LL genotype) = 2.47; 95% CI = 1.21 to 5.03; P(trend) =.011). Fewer AR gene CAG repeats (<23 repeats) were associated with a 1.64-fold (95% CI = 1.00 to 2.68) increased risk of HCC. Although the CYP17 genotype alone did not increase the risk of HCC, there was evidence of a gene-gene interaction, because the CYP17 A1 allele statistically significantly increased the risk of HCC in the presence of fewer AR gene CAG repeats (OR = 2.51; 95% CI = 1.06 to 5.94). We found a similar interaction between the SRD5A2 VV genotype and fewer AR gene CAG repeats (OR = 5.58; 95% CI = 1.86 to 16.71). Body mass index (BMI) modified the association of HCC with testosterone and SRD5A2 genotype; in men with low BMI, multivariate-adjusted ORs for the highest tertile of testosterone versus the lowest and the SRD5A2 VV genotype versus the LL genotype were 7.63 (95% CI = 2.13 to 27.27) and 8.64 (95% CI = 2.75 to 27.14), respectively. No clear associations were found between estradiol or testosterone-to-estradiol ratio and HCC. CONCLUSIONS: Pathways involving androgen signaling may affect the risk of HBV-related HCC among men.

3-Oxo-5-alpha-Steroid 4-Dehydrogenase↗
PubMed2001

Cloning and characterization of hMAP126, a new member of mitotic spindle-associated proteins.

One novel gene product, hMAP126, was demonstrated to interact with p29 in the yeast two-hybrid assay. The full-length cDNA of hMAP126 has been obtained and encodes a protein of 1120 amino acids. Multiple tissue Northern blot analysis showed that hMAP126 was abundantly expressed in the testis. Polyclonal antiserum against hMAP126 was raised and affinity-purification of anti-hMAP126 antibodies was performed. The subcellular distribution of hMAP126 was localized to the mitotic spindle. Furthermore, hMAP126 was identified to be post-translationally modified and phosphorylated by p34(cdc2) kinase in vitro. Taken together, we have isolated a novel protein, hMAP126, which may be involved in the functional and dynamic regulation of mitotic spindles.

Amino Acid Sequence↗
PubMed2001

The p53 codon 249 mutant--derived from human functional adrenal tumors--can modify the cell shape of normal adrenocortical transfected cells.

Our previous study has indicated that p53 gene mutation occurred in 73% of human functional adrenal tumors, and the mutation hot spots were focused on codons 100, 102 (exon 4), and 249 (exon 7). Furthermore, a transcriptional activity study revealed that the mutant p53 protein derived from human functional adrenal tumors lost 90% transcriptional activity and the ability to bind with the p53 sequence. In order to investigate the influence of the mutant protein extracted from adrenocortical tumors on normal adrenal cells, we first cloned p53 cDNA from the human primary aldosteronism and constituted it with isopropyl thiogalactoside (IPTG) inducible expression vector as recombinant plasmid. The recombinant plasmid was then transfected to normal bovine adrenocortical cells through electroporation. The results showed that the p53 protein mutations at codons 100 and 102 could neither affect the cell morphology nor enable cell growth on the soft agar. In addition, no significant difference was found in cortisol level between the p53 transfected and the control cells. On the other hand, cell morphological changes and cell proliferation rate increase were observed when we used IPTG to induce the expression of the p53 protein, which mutated at codon 249, in adrenocortical cells. The cell morphology changes included less flattened and decreased elongation when compared to non-transfected cells. However, the cortisol level in transfected cells was not affected by the p53 mutants. Taken together, we concluded that the mutant p53 protein indeed participates in adrenal carcinogenesis; however, it has no influence on hormone production and secretion.

Adrenal Cortex↗
PubMed2001

Comparison of plasma-sprayed hydroxyapatite coatings and hydroxyapatite/tricalcium phosphate composite coatings: in vivo study.

This study aimed to compare biological properties, including osteoconduction, osseointegration, and shear strength, between plasma-sprayed hydroxyapatite (HA) and HA/tricalcium phosphate (TCP) coatings, using a transcortical implant model in the femora of canines. After 3 and 12 weeks of implantation, the implants with surrounding bone were assessed histologically in undecalcified sections in backscattered electron images (BEIs) under a scanning electron microscope (SEM). After short-term (3 week) follow-up, both coatings conducted new bone formation and revealed direct bone-to-coating contact. The HA/TCP coating could not enhance early host-to-coating responses. At 12 weeks, serious dissolution of the HA/TCP coatings evidently occurred. By the new bone healing index (NBHI) and apposition index (AI), we found no significant difference between HA/TCP-coated implants and HA-coated implants throughout all implant periods. At 12 weeks of implantation, some particles dissociated from the HA/TCP coating were found within the remodeling canal. After push-out measurements, the shear strength and failure mode of HA/TCP-coated implants were similar to those of HA-coated implants, and no statistical differences were found between either coating. Consequently, this study indicates that HA/TCP coatings have excellent biological response and may be considered suitable bioactive ceramic coatings for short-term clinical use.

Animals↗
PubMed2001

Genetic programs of epithelial cell plasticity directed by transforming growth factor-beta.

Epithelial-mesenchymal transitions (EMTs) are an essential manifestation of epithelial cell plasticity during morphogenesis, wound healing, and tumor progression. Transforming growth factor-beta (TGF-beta) modulates epithelial plasticity in these physiological contexts by inducing EMT. Here we report a transcriptome screen of genetic programs of TGF-beta-induced EMT in human keratinocytes and propose functional roles for extracellular response kinase (ERK) mitogen-activated protein kinase signaling in cell motility and disruption of adherens junctions. We used DNA arrays of 16,580 human cDNAs to identify 728 known genes regulated by TGF-beta within 4 hours after treatment. TGF-beta-stimulated ERK signaling mediated regulation of 80 target genes not previously associated with this pathway. This subset is enriched for genes with defined roles in cell-matrix interactions, cell motility, and endocytosis. ERK-independent genetic programs underlying the onset of EMT involve key pathways and regulators of epithelial dedifferentiation, undifferentiated transitional and mesenchymal progenitor phenotypes, and mediators of cytoskeletal reorganization. The gene expression profiling approach delineates complex context-dependent signaling pathways and transcriptional events that determine epithelial cell plasticity controlled by TGF-beta. Investigation of the identified pathways and genes will advance the understanding of molecular mechanisms that underlie tumor invasiveness and metastasis.

Cell Adhesion↗
PubMed2001

Molecular characterization and expression of the recX gene of Xanthomonas campestris pv. citri.

Two genes important in DNA repair, recA and lexA, were recently identified in Xanthomonas campestris pathovar citri (X.c. pv. citri). An open reading frame located immediately downstream of lexA and recA has now been isolated from this pathovar and characterized. This 486-bp open reading frame encodes a protein of 162 amino acids and shares substantial sequence similarity with recX of other bacterial species. The X.c. pv. citri RecX protein was overexpressed in Escherichia coli and purified; SDS-polyacrylamide gel electrophoresis revealed a molecular size of 18 kDa for the purified protein. Whereas Northern blot analysis failed to detect recX mRNA in X.c. pv. citri, recX transcripts were detected in this pathovar by reverse transcription and polymerase chain reaction analysis. The increased abundance of recX transcript in X.c. pv. citri revealed that the recX promoter was activated by exposure of cells to DNA-damaging agents. Southern blot and polymerase chain reaction analyses revealed the presence of a recX-related gene in all nine additional X. campestris pathovars tested. The genetic arrangement of lexA-recA-recX was apparent in X. campestris and each of the three genes transcribed from their own promoters.

Amino Acid Sequence↗
PubMed2001

Structural and functional characterization of the lexA gene of Xanthomonas campestris pathovar citri.

The role of the LexA protein and, specifically, its effect on recA expression were analyzed in Xanthomonas campestris pathovar citri (X.c. pv. citri). Overexpression of LexA from X.c. pv. citri, in the plant pathogen, as well as in Escherichia coli, results in increased sensitivity to the DNA-damaging agents mitomycin C and ultraviolet radiation, indicating that the recombinant X.c. pv. citri LexA protein is functional in a different bacterial species. Immunoblot analysis revealed that the overexpressed LexA protein functioned as a repressor of recA expression in X.c. pv. citri, and that the mitomycin C-induced increase in the abundance of RecA was accompanied by specific proteolysis of LexA that required RecA. Although the LexA protein from X.c. pv. citri also blocked the expression of recA in E. coli, the E. coli RecA protein was not able to support the autocatalytic cleavage of LexA from the plant pathogen. The transcription start site of the X.c. pv. citri lexA gene was identified, and the region upstream of this gene was shown to confer responsiveness to mitomycin C on a luciferase reporter gene construct. Electrophoretic mobility-shift assays demonstrated that X.c. pv. citri LexA interacts with the promoter region of X.c. pv. citri lexA, as well as with those of the recA genes of X.c. pv. citri and E. coli. These results indicate that LexA functions as a repressor of gene expression in X.c. pv. citri just as it does in E. coli.

Bacterial Proteins↗