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W Y Chen

Publications and source records attributed to W Y Chen.

At least 37 records · Page 2Linked to original sources
PubMed2001

Microcalorimetric studies of the interaction mechanisms between proteins and Q-sepharose at pH near the isoelectric point (pI) effects of NaCl concentration, pH value, and temperature.

This study examined the interaction mechanisms of beta-lactoglobulins A and B (Lg A, Lg B) with an anion exchanger, Q-Sepharose at pH near the isoelectric point at which the proteins are expected to be electrically neutralized under various NaCl concentrations and temperatures by the equilibrium binding analysis and the adsorption enthalpy directly measured by isothermal titration calorimetry. The data evaluated from isotherms fitted by the Langmuirean model reveal that the addition of NaCl considerably reduced the binding affinities and capacities of both the proteins with Q-Sepharose at pH 5.2, indicating that electrostatic forces are dominant during the adsorption. However, the hydrophobic interaction seems to be involved in adsorption as well at a higher NaCl concentration, and the adsorption enthalpies confirm this suggestion. In addition, the effects of temperature on the equilibrium binding behaviors for Lg A or Lg B with Q-Sepharose were found to be salt concentration-dependent, probably due to their different binding mechanisms at 0.03 M and 0.3 M NaCl. Where, at 0.3 M NaCl, the hydrophobic interaction plays a more pronounced role. This implication was again supported by the adsorption enthalpies. The presented data provide further insight to the interaction mechanisms between proteins and ion exchangers, facilitating the optimization of protein separations.

Calorimetry↗
PubMed2001

On-line, continuous and automatic monitoring of extracellular malondialdehyde concentration in anesthetized rat brain cortex.

An assay for in vivo, continuous and automatic monitoring of extracellular malondialdehyde concentrations in anesthetized rat brain cortex was developed. This method involved the use of microdialysis perfusion, on-line derivatization and on-line high-performance liquid chromatographic analysis. Microdialysate from an implanted microdialysis probe was on-line reacted with thiobarbituric acid at 80 degrees C for 10 min prior to on-line collection and automatic injection into a HPLC system equipped with a fluorescence detector. This method gave a linear response between the concentrations of the malondialdehyde in the microdialysates and the TEP solution where the microdialysis probe was placed. This method was used to observe the increased extracellular malondialdehyde production following elevated extracellular glutamate levels, which were achieved by perfusion of L-trans-pyrrolidine-2,4-dicarboxylate, a competitive inhibitor of glutamate uptake transporter.

Animals↗
PubMed2001

Primary leiomyosarcoma of bone.

We report a case of primary leiomyosarcoma in the right femoral diaphysis. Conventional radiographs revealed an indistinct osteolytic lesion with a very subtle periosteal reaction. MR imaging revealed an intramedullary lesion with a well-defined margin, cortical breakthrough and soft tissue extension. The lesion was isointense relative to muscle on T1-weighted imaging, iso-hypointense relative to fat on fast spin echo T2-weighted imaging, and hyperintense to muscle on fast spin echo T2-weighted imaging with fat saturation. A peripheral rim and intratumoral spoke-wheel-like enhancement in the soft tissue component of the tumor was noted on gadolinium-enhanced T1-weighted imaging with fat saturation. Such an enhancing pattern, which has not been described in the literature previously but has been seen in leiomyosarcomas elsewhere by both MR imaging and computed tomography, deserves further pathological correlation.

Adult↗
PubMed2001

Corneal haze after photorefractive keratectomy using different epithelial removal techniques: mechanical debridement versus laser scrape.

PURPOSE: To determine differences of corneal wound healing and haze after photorefractive keratectomy (PRK) using either mechanical epithelial debridement or laser-scrape epithelial removal in human subjects. DESIGN: A 6-month randomized, masked, prospective, paired-eye clinical study. PARTICIPANTS: Twenty eyes in 10 myopic patients treated between March 1999 and May 1999. INTERVENTION: Photorefractive keratectomy treatments with two different epithelial removal techniques. Continuous z-scan of confocal image, termed confocal microscopy through focusing (CMTF), was performed before surgery and at 3 weeks, 6 weeks, 3 months, and 6 months after surgery. MAIN OUTCOMES MEASURES: Epithelial and stromal thickness measurement, achieved stromal ablation depth, and objective assessment of corneal light-backscattering (corneal haze) were obtained from digital image analysis of the CMTF scans. Manifest refraction was also measured. Student's paired t test or two-way repeated-measures analysis of variance after rank transformation were performed to evaluate statistical differences between groups. RESULTS: Comparison of the mean posttreatment spherical equivalent between the two techniques showed no statistically significant difference. In preoperative corneas, mean epithelial thickness was 50.08+/-3.70 microm in the mechanical debridement group and 50.49+/-4.01 microm in laser-scrape group (not significant). For both groups, the epithelium was significantly thinner at 3 weeks, but returned to preoperative values by 6 months, with no difference between groups. Planned stromal ablation depth by PRK was 59.38+/-11.48 microm (39-73 microm; n = 8) in the mechanical group and 57.75 +/- 7.21 microm (48-70 microm; n = 8) in the laser-scrape group. Achieved stromal ablation depth was not significantly different between the two groups. Most importantly, in both groups CMTF-measured corneal haze increased significantly after surgery, peaked at 3 months, and then decreased at 6 months, with no significant difference between groups. (Power = 0.96). CONCLUSIONS: There is no significant difference in the corneal wound healing response between mechanical epithelial debridement versus laser-scrape technique in human myopic eyes undergoing PRK.

Adult↗
PubMed2001

Intestinal metastasis causing intussusception in a patient treated for osteosarcoma with history of multiple metastases: a case report.

Intestinal intussusception caused by metastatic tumors is a very rare condition. Preoperative diagnosis is not easy because of the condition's rarity and because of mild abdominal physical presentation. We report on a patient with osteosarcoma who suffered from abdominal pain and emesis during the period of autologous peripheral blood stem cell transplantation. He had undergone tumor excision and radiotherapy several times prior to autologous peripheral blood stem cell transplantation because of multiple metastases. Intestinal metastasis was suspected initially by computed tomographic scan and sonogram and was proved by surgical resection and pathological findings. Clinicians caring for pediatric patients with osteosarcoma with a history of multiple metastases should consider the possibility of intestinal metastases when equivocal abdominal symptoms develop after intensive chemotherapy.

Adolescent↗
PubMed2001

Spindle cell and mixed spindle/lymphocytic thymomas: an integrated clinicopathologic and immunohistochemical study of 81 cases.

Forty-three cases of spindle cell thymoma (medullary, WHO type A) and 38 cases of mixed spindle/lymphocytic thymoma (WHO type AB) were studied for their clinicopathologic and immunohistochemical characteristics. Three histologic patterns of spindle cell thymoma were observed: short-spindled (57%), long-spindled (31%), and micronodular (12%). The short-spindled variant was composed of oval to short spindle cells commonly arranged in a hemangiopericytic or microcystic pattern. The long-spindled variant chiefly consisted of fibroblast-like epithelial cells mimicking fibrohistiocytic neoplasms. The micronodular variant was characterized by small nests of short spindle cells dispersed among a lymphoid stroma with frequent germinal centers. All kinds of spindle cell could be admixed with lymphocyte-rich "cortex"-like areas to constitute mixed spindle/lymphocytic thymomas. Immunohistochemically, the epithelial cells in up to 70% of the short-spindled and long-spindled variants of spindle cell thymoma and 90% of mixed spindle/lymphocytic thymomas were positive for CD20, whereas the epithelial cells in all micronodular spindle cell thymomas were negative. All of the spindle cell thymomas and most of the mixed spindle/lymphocytic thymomas in this study were found in stages I and II. Follow up of the patients did not disclose relapse or mortality directly resulting from the tumors. However, the prognosis of stage I and II spindle cell and mixed spindle/lymphocytic thymomas did not significantly differ from those of stage I and II thymomas of other types by a stage-matched survival analysis. Our data showed that spindle cell and mixed spindle/lymphocytic thymomas are distinctive in histologic pattern and immunohistochemical profile. When interpreted within the context of staging, spindle cell and mixed spindle/lymphocytic thymomas presenting in stages I and II most likely behave in an indolent fashion.

Adult↗
PubMed2001

Quantification of prolactin receptor mRNA in multiple human tissues and cancer cell lines by real time RT-PCR.

Human prolactin (hPRL) has been reported to be involved in breast and prostate cancer development. The hPRL receptor (hPRLR) is expressed in a wide variety of tissues in at least three isoforms. In this study, a one-step real time reverse transcription PCR technique was used to determine relative expression levels of hPRLR mRNA in eleven human breast cancer cell lines, HeLa cells, three prostate cancer cell lines and nine normal human tissues. The housekeeping gene beta-actin was used for internal normalization. We demonstrate that hPRLR mRNA is up-regulated in six of the eleven breast cancer cell lines tested when compared with normal breast tissue. Of the cancer cell lines tested, we found that T-47D cells have the highest level of hPRLR mRNA, followed by MDA-MB-134, BT-483, BT-474, MCF-7 and MDA-MB-453 cells. In two breast cancer cell lines (MDA-MB-468 and BT-549), the hPRLR levels were found to be comparable to that of normal breast tissue. Three breast cancer cell lines (MDA-MB-436, MDA-MB-157 and MDA-MB-231) expressed hPRLR mRNA at levels lower than that of normal tissue. In contrast, in all three commonly used prostate cancer cell lines (LNCaP, PC-3 and DU 145), the levels of hPRLR mRNA were found to be down-regulated relative to that of normal prostate tissue. Of nine normal human tissues tested, we found that the uterus and the breast have the highest levels of hPRLR mRNA, followed by the kidney, the liver, the prostate and the ovary. The levels of hPRLR mRNA were the lowest among the trachea, the brain and the lung.

Adult↗
PubMed2001

Combination of PCR subtraction and cDNA microarray for differential gene expression profiling.

PCR subtraction hybridization has been used effectively to enrich and single out differentially expressed genes. However identification of these genes by means of cloning and sequencing individual cDNAs is a tedious and lengthy process. In this report, an attempt has been made to combine the use of PCR select cDNA subtraction hybridization and cDNA microarrays to identify differentially expressed genes using a nonradioactive chemiluminescent detection method. mRNA from human prolactin (hPRL) or human prolactin antagonist (hPRL-G129R) treated and non-treated breast cancer cells was isolated, and cDNAs were synthesized and used for the PCR subtraction to enrich the differentially expressed genes in the treated cells. The PCR-amplified and subtracted cDNA pools were purified and labeled using the digoxigenin method. Labeled cDNAs were hybridized to a human apoptosis cDNA microarray membrane and identified by chemiluminescence. The results suggest that the strategy of combining all three methods will allow for a more efficient, nonradioactive way of identifying differentially expressed genes in target cells.

Biotechnology↗
PubMed2001

In vitro studies of a prolactin antagonist, hPRL-G129R in human breast cancer cells.

Human prolactin (hPRL) has been shown to be one of the important survival/growth factors that promotes the proliferation of breast cancer cells in an autocrine/paracrine manner. In our recent studies, we demonstrated that a hPRL antagonist with a single amino acid substitution mutation (hPRL-G129R) was able to inhibit breast cancer cell proliferation via induction of apoptosis (1). In this study three independent yet related experiments were carried out regarding the effects of hPRL-G129R in breast cancer cells. We investigated the possible mechanism(s) of hPRL-G129R induced apoptosis in breast cancer cells. It is well documented that transforming growth factors (TGF) in conjunction with hormones such as estrogen and PRL play a major role in modulating the proliferation and apoptosis of mammary cells. We first investigated the relationships between hPRL/hPRL-G129R and TGFs. We show that hPRL is able to down-regulate TGF beta 1 (apoptotic factor) secretion and up-regulate TGF alpha (survival factor) secretion in a dose-dependent manner in T-47D cells. More importantly the hPRL antagonist up-regulates TGF beta 1 and down-regulates TGF alpha secretion. When hPRL-G129R was applied together with hPRL, it blocked the effects of hPRL. Secondly, we tested the possible involvement of caspases in hPRL-G129R induced apoptosis. We have shown that caspase-3 is activated by hPRL-G129R at a concentration of 250 ng/ml in T-47D breast cancer cells. Thirdly, we explored the additive effects of an anti-neoplastic drug, cisplatin, with the hPRL-G129R in T47D breast cancer cells. We show that cisplatin and hPRL-G129R when applied together resulted in about 40% growth inhibition in T-47D cells.

Amino Acid Substitution↗
PubMed2001

Ductal adenocarcinoma of the prostate with endometrioid features in a 69-year-old man.

We describe a case of ductal adenocarcinoma of the prostate with endometrioid characteristics presenting as painless hematuria and intraurethral tumor. A 69-year-old man had intermittent painless hematuria for 2 months. The serum prostate-specific antigen concentration was elevated (22.0 ng/mL). An enlarged prostate with a necrotic tumor was noted in the right lobe of the prostate on computerized tomography and magnetic resonance imaging studies. A polypoid and worm-like tumor was found within the prostatic urethra near the verumontanum. The tumor had a distinctly papillary configuration with a focal glandular structure on microscopy. Radical prostatectomy was performed and histology of the tumor specimen revealed it to be composed of a closely packed glandular structure lined by single layers of high columnar cells with focal stratification. Frequent papillary projections of glandular epithelium and intraglandular bridging were noted, with a histopathologic appearance similar to endometrioid carcinoma of the uterus. Androgen deprivation therapy was started immediately following surgery. No evidence of recurrence or metastasis was found at follow-up 27 months postoperatively. Distinct features of ductal adenocarcinoma of the prostate include intraurethral papillary tumor close to the verumontanum, urethral obstruction, and easy bleeding of the tumor. Its more aggressive behavior than classical microacinar adenocarcinoma of the prostate makes early recognition of this type of prostatic malignancy important.

Aged↗
PubMed2000

Effects of naloxone on lactate, pyruvate metabolism and antioxidant enzyme activity in rat cerebral ischemia/reperfusion.

Whether naloxone may modulate energy metabolism and endogenous antioxidant enzyme activities in ischemic cortex was studied. Cerebral ischemia/reperfusion (I/R) was produced by occluding two common carotid arteries and the right middle cerebral artery for 90 min followed by reperfusion in anesthetized Sprague-Dawley rats. Both pre-treatment (0.03 or 0.3 mg) and post-treatment (0.3 mg) of naloxone by intracerebroventricular infusion significantly reduced cortical infarct volumes. Pre-treatment with 0.03 mg reduced ischemia-induced suppression of extracellular pyruvate level and enhancement of lactate/pyruvate ratio as well as cerebral I/R-induced increases of endogenous catalase, glutathione peroxidase, and manganese superoxide dismutase activities. In conclusion, neuroprotective effects of naloxone in terms of reducing brain infarction involve attenuation of the disturbance of cellular functions following cerebral I/R via restoration of mitochondrial activities or energy metabolism.

Animals↗
PubMed2000

Microcalorimetric studies of interactions between proteins and hydrophobic ligands in hydrophobic interaction chromatography: effects of ligand chain length, density and the amount of bound protein.

Using isothermal titration calorimetry (ITC), this investigation directly measured the adsorption enthalpies of proteins on various hydrophobic adsorbents. Various amounts of butyl and octyl groups were attached onto CM-Sepharose to form C4 and C8, two types of hydrophobic adsorbents. The adsorption enthalpies of both trypsinogen and alpha-chymotrypsinogen A were measured at 4.0 M NaCl and pH 10.0, in which most ionic interaction was suppressed. The adsorption isotherms of both proteins on various adsorbents were also measured, thus allowing us to calculate the Gibbs free energy and entropy of adsorption. Experimental results indicated that the adsorption of both proteins on butyl-containing adsorbents was exothermic, while their adsorption on octyl ones was endothermic. In addition, binding of both proteins with the butyl ligand is basically an adsorption process, while binding with the octyl ligand is adsorption and partition processes. Moreover, on both butyl or octyl, the adsorption enthalpy became increasingly positive as the ligand density increased, while the adsorption entropy became more positive as the alkyl chain length or density of the adsorbent increased. In addition, ITC was used to measure protein-protein interaction. The adsorption enthalpy of both proteins increased as the amount of bound protein increased, and the enthalpy increase of trypsinogen appeared to be higher than that of alpha-chymotrypsinogen A. This observation implies that protein-protein repulsion was stronger among trypsinogen molecules in the experiments.

Calorimetry↗
PubMed2000

Molecular mechanism for silencing virally transduced genes involves histone deacetylation and chromatin condensation.

Virally transduced genes are often silenced after integration into the host genome. Chromatin immunoprecipitation and nuclease sensitivity experiments now demonstrate that silencing of the transgene is characterized by deacetylation of histone H4 lysines and chromatin condensation. Trichostatin A treatment results in dramatic reactivation of gene expression that is preceded by histone acetylation and chromatin decondensation. Analysis of individual histone H4 lysines demonstrate that chromatin domain opening is coincident with rapid acetylation of histone H4 K5, K12, and K16 and that maintenance of the open domain is correlated with acetylation of histone H4 K8. Removal of trichostatin A results in rapid deacetylation of histone H4 K8, chromatin condensation, and transcription silencing. The results suggest that deacetylation of histone H4 lysines and coincident chromatin condensation are critically involved in the silencing of virally transduced genes.

Acetylation↗
PubMed2000

Effect of dexamethasone on the expression of p34(cdc2) and cyclin B1 in pig oocytes in vitro.

The meiotic division in oocytes is arrested in the G2 phase of the cell cycle. Resumption of meiosis, also known as oocyte maturation, entails a G2 to M transition. At the G2-M boundary, maturation promoting factor (MPF) activation is usually induced via several ways, including tyrosine dephosphorylation of p34(cdc2) and synthesis of cyclin B according to cell type and species. Previous studies in our laboratory demonstrated that glucocorticoids directly inhibit the meiotic maturation of pig oocytes in vitro. The aim of this study was therefore to investigate the influence of glucocorticoids on the expression of p34(cdc2) and cyclin B1 in resumption of meiosis of pig oocytes. We detected the relative levels and association of p34(cdc2) and cyclin B1. Isolated cumulus-enclosed oocytes were cultured in Waymouth MB752/1 medium supplemented with sodium pyruvate (50 microgram/ml), LH (0.5 microgram/ml), FSH (0.5 microgram/ml), and estradiol-17beta (1 microgram/ml) in the presence or absence of dexamethasone (DEX) for 24 hr; they then were cultured without hormonal supplements in the presence or absence of DEX for an additional 24 hr. We found that cyclin B1, as well as p34(cdc2), was already present in fully grown G2-arrested pig oocytes when removed from the follicle. In these oocytes, cyclin B1 and p34(cdc2) were already associated in complex. Treatment with DEX at concentrations of 1 microgram/ml or above decreased the level of cyclin B1, but had no effect on the level of p34(cdc2). The exposure of oocytes to DEX also decreased the amount of complexed p34(cdc2)-cyclin B1. These findings suggest that the inhibitory action of DEX on meiotic maturation could be due, at least in part, to the reduced amount of p34(cdc2)-cyclin B1 complex.

Animals↗
PubMed2000

A DPDPE-induced enhancement of inward rectifier potassium current via opioid receptor in neuroblastomaxglioma NG108-15 cells.

The effect of a delta-selective opioid agonist, DPDPE([D-Pen(2, 5)]-enkephalin), on the inward rectifier potassium current (I(KIR)) of NG108-15 cell was studied by whole cell voltage-clamp technique. It was found that microM DPDPE increased the amplitude and delayed the activation and inactivation of I(KIR) rapidly and reversibly. These effects could be reversed by naloxone, but were still obtained in pertussis toxin (PTX) preincubated cells or when using GDP-betas (guanosine 5'-o-[2-thio] diphoaphate) containing electrodes to block the G-protein coupled events. The above results suggest that DPDPE-induced change of I(KIR) is mediated by delta-opioid receptor but does not involve G-proteins.

Animals↗
PubMed2000

Differential expression of ras in organs and embryos of shrimp Penaeus monodon (Crustacea: Decapoda).

Total RNA from shrimp hepatopancreas of Penaeus monodon showed three prominent bands that react with the shrimp ras probe, a 239-bp product, of approximately 4.8 kb (R1), 3.1 kb (R2) and 1.3 kb (R3) on the northern blot. The R1 is the least abundant. Analyses of total RNA from gill and heart were similar to each other. The highest expression of Ras was observed in the gill, while a negligible signal was detected with the Ras probe in muscle. Ras expression is developmentally regulated in embryonic stages of shrimp. Messenger RNA levels of ras were increased from a minimum in the nauplius stage to a maximum in the post-larvae stage for R1 and R2. R3 showed a maximum at the protozoea stage. On the other hand, the activity of protein geranylgeranyltransferase I was increased significantly in the early nauplius stage. No correlative increase of prenylation activity by protein geranylgeranyltransferase I was observed with the transcription activity of ras.

Amino Acid Sequence↗
PubMed2000

Trace Metals' abnormalities in hemodialysis patients: relationship with medications.

A multicenter collaborative study was performed to investigate the prevalence of abnormal blood contents of 6 trace metals, copper (Cu), zinc (Zn), aluminum (Al), lead (Pb), cadmium (Cd), and mercury (Hg), in hemodialysis (HD) patients and to analyze their relationship with the medications, such as CaCO3, Ca acetate, Al containing phosphate-binding agents, 1,25-dihydroxy vitD3, 1-hydroxy vitD3, and erythropoietin (EPO), as well as hematocrit level, by chi-square statistics. From 6 medical centers in Taiwan, we included 456 patients in maintenance HD for more than 4 months for this study, and they had continued the previously mentioned medications for at least 3 months. Blood samples were collected before initiating HD, and atomic absorption spectrophotometry was used to measure plasma levels of Cu, Zn, and Al as well as whole blood levels of Pb, Cd, and Hg. Three hundred seventy-five (78%) of the HD patients had low plasma Zn levels, that is, <800 microg/L, and the mean (+/-SD) concentration was 705.8 (+/-128.23) microg/L in all subjects. One hundred forty-one (31%) of the HD patients had high plasma Al, that is, >50 microg/L, and the mean (+/-SD) was 44.30 (+/-28.28) microg/L in all subjects. Three hundred thirty-three (73%) of the dialysis patients had high Cd levels, that is, >2.5 microg/L, and the mean (+/-SD) was 3.32 (+/-1.49) microg/L in all subjects. The majority of HD patients had normal blood levels of Cu, PB, and Hg. Only 21 (4. 6%), 5 (1.1%), and 3 (0.06%) patients had elevated blood levels of Cu, Pb, and Hg, respectively. Their mean (+/-SD) blood concentration of Cu, Pb, and Hg were 1,049.78 (+/-233.25) microg/L, 7.45 (+/-3.95) microg/dL, and 3.17 (+/-25.56) microg/L, respectively. Three patients had elevated plasma Hg concentrations, that is, 546, 12.6, and 24.0 microg/L, respectively. In the 152 normal healthy age and sex matched control group, the blood levels of Al, Cd, and Pb were all significantly lower than the HD patients. However, the levels of Cu and Zn were higher in the control group. The Hg level was not significantly different in both groups. There was no statistical difference between patients with normal and abnormal blood levels of trace metals in various medications except Al containing phosphate binder. The Al containing phosphate binder users had significantly higher plasma Al levels (54.71 +/- 26.70 versus 41.15 +/- 28.03 microg/L, p < 0.001) and hematocrit levels (29.61 +/- 4.61 versus 27. 81 +/- 3.91, p < 0.0005). There was no statistical correlation between erythropoietin (EPO) dose and hematocrit level in these patients. In conclusion, the blood level of trace metals of these HD patients except Al was not related to their medications. However, caution must be exercised in interpreting this result as dose and duration of medication; efficiency of HD and water treatment may play an important role. Otherwise, environmental factors, diet, and the aging process may contribute to the trace metal burden in uremia. Thus, Zn and Cu are abundant in seafood, and Cd is abundant in contaminated plants such as rice.

Acetates↗