Biomedical subjects

Wei Chen

Publications and source records attributed to Wei Chen.

At least 91 records · Page 5Linked to original sources

PubMed2006

Progesterone receptor modulator CDB-2914 down-regulates vascular endothelial growth factor, adrenomedullin and their receptors and modulates progesterone receptor content in cultured human uterine leiomyoma cells.

BACKGROUND: This study was conducted to evaluate the effects of graded concentrations (10(-8), 10(-7) and 10(-6) M) of progesterone receptor (PR) modulator CDB-2914 on the protein contents of PR, of vascular endothelial growth factor (VEGF), adrenomedullin (ADM) and their receptors in cultured human uterine leiomyoma and matching myometrial cells. METHODS: PR-A, PR-B, VEGF-A, VEGF-B, VEGF receptor (VEGFR)-1, VEGFR-2, ADM and ADM receptor (ADMR) contents were assessed by Western blot analysis. RESULTS: Treatment with 100 ng/ml progesterone increased VEGF-A, VEGF-B and ADM contents in cultured leiomyoma cells and normal myometrial cells. The concomitant treatment with 10(-6) M CDB-2914 significantly decreased the progesterone-induced VEGF-A, VEGF-B and ADM contents in cultured leiomyoma cells but not in normal myometrial cells. CDB-2914 treatment alone decreased VEGFR-1, VEGFR-2 and ADMR contents in cultured leiomyoma cells but not in normal myometrial cells. CDB-2914 treatment increased PR-A and decreased PR-B contents in cultured leiomyoma cells in a dose-dependent manner compared with untreated cultures, whereas no significant changes in PR isoform contents were observed in normal myometrial cells. CONCLUSIONS: These results suggest that CDB-2914 down-regulates VEGF, ADM and their receptor contents and modulates PR isoform contents in cultured leiomyoma cells in a cell-type-specific manner.

Adrenomedullin↗

PubMed2006

Quantum chemical study of adsorption and dissociation of H2S on the gallium-rich GaAs (001)-4 x 2 surface.

H(2)S adsorption and dissociation on the gallium-rich GaAs(001)-4 x 2 surface is investigated using hybrid density functional theory. Starting from chemisorbed H(2)S on the GaAs(001)-4 x 2 surface, two possible reaction routes have been proposed. We find that H(2)S adsorbs molecularly onto GaAs(001)-4 x 2 via the formation of a dative bond, and this process is exothermic with adsorption energy of 6.6 kcal/mol. For the first reaction route, one of the H atoms from the chemisorbed H(2)S is transferred to a second-layer As atom and the dissociated SH is inserted into the Ga-As bond with an activation barrier of 8.2 kcal/mol, which is found to be 29.3 kcal/mol more stable than the reactants. For the second case, the dissociated species may insert themselves into the Ga-Ga dimer resulting in the Ga-H-Ga and Ga-HS-Ga bridge-bonded states, which are found to be 29.8 and 22.2 kcal/mol more stable than the reactants, respectively. However, the calculations also show that the activation barrier (16.1 kcal/mol) for chemisorbed H(2)S dissociation through the second route is higher than the transfer of one H atom into a second-layer As atom. As a result, we conclude that sulfur insertion into the Ga-As bond is more kinetically favorable.

Journal Article↗

PubMed2006

Novel superalkali superhalogen compounds (Li3)+(SH)- (SH=LiF2, BeF3, and BF4) with aromaticity: new electrides and alkalides.

Optimized structures, with all real frequencies, of superalkali superhalides (Li(3))(+)(SH)(-) (SH=LiF(2), BeF(3), and BF(4)), are obtained, for the first time, at the B3LYP/aug-cc-pVDZ and MP2/aug-cc-pVDZ computational levels. These superalkali superhalides possess three characteristics that are significantly different from normal alkali halides. 1) They have a variety of structures, which come from five bonding mode types: edge-face, edge-edge, face-face, face-edge, and staggered face-edge. We find that the bonding mode type closely correlates with the Li(3)-SH bond energy. 2) The valence electrons on the Li(3) ring are pushed out by the (SH)(-) anion, and become excess electrons, conferring alkalide or electride characteristics on these Li(3)-SH species, depending on the bonding mode type. 3) The highest occupied molecular orbital of each Li(3)-SH species is a doubly occupied delocalized sigma bonding orbital on the Li(3) ring, which indicates its aromaticity. It is noticeable that the maximum negative nucleus-independent chemical shift value (about -10 ppm) moves out from the center of the Li(3) ring, owing to repulsion by the SH(-) anion. We find that these superalkali superhalides are not only complicated "supermolecules", but are also a new type of alkalide or electride, with aromaticity.

Journal Article↗

PubMed2006

A genome scan for loci influencing levels and trends of lipoprotein lipid-related traits since childhood: The Bogalusa Heart Study.

Coronary heart disease is the result of life-long processes. Previous genetic linkage analyses of lipid and lipoprotein variables that can be measured throughout life have focused on a single measure at one point in time. Genome-wide linkage analyses were performed in the present study to identify loci influencing the long-term levels and trends of high-density lipoprotein cholesterol (HDLC) and low-density lipoprotein cholesterol (LDLC) and triglycerides in a longitudinal cohort. Microsatellite markers (n=357) were typed on 779 white and 444 black siblings, ages 14-43 years. Subjects had been examined serially 2-13 times with 6963 serial observations over an average of 22 years from childhood to adulthood. Total and incremental area under the growth curves of lipid traits was calculated and used as measures for long-term levels and trends. After adjusting for age, sex and body mass index, heritability estimates of total area values for all lipid variables were higher than those of a single measurement in either childhood or adulthood. In blacks, significant linkage to LDLC incremental area (peak LOD=3.6 at 50 cM) was observed on chromosome 1; and suggestive linkage for total area of LDLC (LOD=2.9 at 21 cM) on chromosome 19. Only one suggestive linkage (LOD=2.2 at 161 cM) on chromosome 2 was identified in whites for LDLC incremental area. Other suggestive linkage (LOD> or =2.0) was noted for LDLC and HDLC in terms of either total or incremental area on chromosomes 2, 5, 7 and 15 for blacks and whites. Several lipid-related candidate genes such as low-density lipoprotein receptor (LDLR), LDL receptor-related proteins 3 and 8, ApoE, ApoAII and ApoCII are located in these regions. Linkage evidence found in this community-based study indicates that regions on these chromosomes harbor genetic loci that affect the propensity to develop dyslipidemia from childhood.

Adolescent↗

PubMed2006

Functional cortical source imaging from simultaneously recorded ERP and fMRI.

Feasibility of continuously and simultaneously recording visual evoked potentials (VEPs) with fMRI was assessed by quantitatively comparing cortical source images by means of receiver operating characteristic (ROC) curve analysis. The averaged EEG source images coincided well with simultaneously acquired fMRI activations. Strong correlation was found between the cortical source images of VEPs recorded inside and outside the scanner. Application of fMRI prior information strengthened correlation between estimated source images as well as resulted in source estimates with higher spatial resolution. The present results demonstrate that reliable cortical source images can be acquired during simultaneous fMRI scanning and they may be used for multimodal functional source imaging studies.

Adult↗

PubMed2006

Invariants of DNA sequences based on 2DD-curves.

The leading eigenvalue of the matrix associated with a DNA sequence as a important invariant is effectively used in analysis of DNA sequences. Here, we propose a new invariant base on the 2DD-Curves of DNA sequences which is simple for calculation. We can use it as an alternative invariant to characterize the DNA sequence. The utility of the new parameter is illustrated on the DNA sequences of 11 species.

Animals↗

PubMed2006

Residual renal function and volume control in peritoneal dialysis patients.

BACKGROUND: Fluid overload is not uncommon in patients on continuous ambulatory peritoneal dialysis (CAPD). Previous studies suggested that residual renal function (RRF) played an important role in maintaining fluid balance. However, good fluid status should be a balance between fluid intake and removal. Therefore, in the present study, we investigated the effect of RRF on patients' fluid status after focusing on the balance between fluid intake and removal in CAPD patients. METHODS: In this cross-sectional study, 195 stable CAPD patients in a single center were included. Patients were divided into three groups according to their urine output: anuric group with urine < or =100 ml/day, oliguric group with urine < or =400 ml/day and UO >400 ml group with urine >400 ml/day. Fluid status was evaluated by bioimpedance analysis and mean arterial pressure (MAP). The sodium removal and plasma sodium concentration were also measured. All the patients were educated to try to achieve good volume control by focusing on salt and fluid intake and their removals. RESULTS: There were 51, 31 and 113 patients in anuric, oliguric and UO >400 ml group, respectively. Anuric patients were older and had been on CAPD longer than that of the oliguric and UO >400 ml patients (p < 0.05). The urine output in the three groups were 9.28 +/- 22.68, 236.13 +/- 75.43 and 1,013.34 +/- 541.54 ml/day, respectively (p < 0.001). Bioimpedance analysis showed that the differences of extracellular water, intracellular water and total body water were not statistically significant among the three groups. However, there was significant difference in MAP among the three groups (MAP in anuric, oliguric and UO >400 ml groups were 93.27 +/- 13.35, 96.63 +/- 9.94 and 102.36 +/- 13.70 mm Hg, p < 0.01), and UO >400 ml group had higher MAP than anuric and oliguric groups (p < 0.05). The total sodium removal (renal + peritoneal) in anuric, oliguric and UO >400 ml groups were 96.44 +/- 60.18, 98.95 +/- 73.82 and 134.64 +/- 72.44 mmol/day, respectively (p < 0.01). The UO >400 ml group also had higher plasma sodium concentration than anuric and oliguric groups (plasma sodium in the three groups were 137.49 +/- 3.43, 137.82 +/- 2.63 and 139.15 +/- 3.30 mmol/l, respectively; p < 0.01). CONCLUSIONS: This study showed that extracellular water among anuric, oliguric and UO >400 ml groups was not significantly different, which suggested that RRF may be not so important as expected in maintaining good volume status. The higher blood pressure in patients with higher RRF and higher sodium and fluid removal in the present study suggested restricting salt and fluid intake might be more important for better blood pressure control in CAPD patients.

Antihypertensive Agents↗

PubMed2006

Insulin reduces the BOLD response but is without effect on the VEP during presentation of a visual task in humans.

Functional magnetic resonance imaging (fMRI) based on blood oxygen level-dependent (BOLD) contrast has become an invaluable tool in the assessment of in vivo neuronal activation. Quantification of the BOLD response is determined by the hemodynamic and metabolic changes that occur in response to brain stimulation. However, these changes may vary by changes in insulin, a hormone known to be vasoactive in some tissues. To determine if insulin has an effect on fMRI, we measured the BOLD response to a visual stimulus in five normal volunteers in which insulin was first suppressed and then brought to a high physiological concentration. In addition, we also examined the effect of insulin on activation of the visual cortex as measured by the visual-evoked potential (VEP). We found that the BOLD response measured in the presence of insulin (serum insulin=236+/-29 pmol/L) was significantly lower (P<0.001) than that measured in its absence (serum insulin=8+/-2 pmol/L). Insulin was without effect on P100 amplitude or latency acquired in the presence or absence of insulin in 28 subjects using the same stimulus as that used for the fMRI experiments. Our observations suggest that insulin may have effects on cerebral blood flow and/or metabolism that affect the BOLD signal that are independent of its effects on neuronal activation identified by event related potentials (ERP). These findings highlight the complexity that must be considered when interpreting differences in fMRI responses between groups of subjects that differ in insulin concentration and/or insulin sensitivity.

Adolescent↗

PubMed2006

Sorption, degradation and mobility of microcystins in Chinese agriculture soils: Risk assessment for groundwater protection.

In the present paper, sorption, persistence, and leaching behavior of three microcystin variants in Chinese agriculture soils were examined. Based on this study, the values of capacity factor and slope for three MCs variants in three soils ranged from 0.69 to 6.00, and 1.01 to 1.54, respectively. The adsorption of MCs in the soils decreased in the following order: RR > Dha7 LR > LR. Furthermore, for each MC variant in the three soils, the adsorption rate in the soils decreased in the following order: soil A > soil C > soil B. The calculated half-time ranged between 7.9 and 17.8 days for MC-RR, 6.0-17.1 days for MC-LR, and 7.1-10.2 days for MC-Dha7 LR. Results from leaching experiments demonstrated that recoveries of toxins in leachates ranged from 0-16.7% for RR, 73.2-88.9% for LR, and 8.9-73.1% for Dha7 LR. The GUS value ranged from 1.48 to 2.06 for RR, 1.82-2.88 for LR, and 1.76-2.09 for Dha7 LR. Results demonstrated the use of cyanobacterial collections as plant fertilizer is likely to be unsafe in soils.

Adsorption↗

PubMed2006

CNBP regulates forebrain formation at organogenesis stage in chick embryos.

We recently demonstrated that Cellular Nucleic acid Binding Protein (CNBP)(-/-) mouse embryos exhibit forebrain truncation due to a lack of proper morphogenetic movements of the anterior visceral endoderm (AVE) during pre-gastrulation stage (Chen, W., Liang, Y., Deng, W., Shimizu, K., Ashique, A.M., Li, E., Li, Y.P., 2003. The zinc-finger protein CNBP is required for forebrain formation in the mouse, Development 130, 1367-1379). However, CNBP expression pattern in the mouse forebrain suggests that CNBP may have more direct effects during forebrain development. Our data show that CNBP is expressed in tissues of early chick embryo that are the equivalent to the mouse embryo. Using a combination of RNAi-silencing and Retrovirus-misexpression approaches, we investigated the temporal function of CNBP in the specification/development of the chick forebrain during organogenesis. The silencing of CNBP expression resulted in forebrain truncation and the absence of BF-1, Six3 and Hesx1 expression, but not Otx2 in chick embryos. Misexpression of CNBP induced the expression of BF-1, Six3 and Hesx1 in the hindbrain, but not the expression of Otx2. These results offer novel insights into the function of CNBP during organogenesis as the regulator of forebrain formation and a number of rostral head transcription factors. Moreover, CNBP and Otx2 may play roles as regulators of forebrain formation in two parallel pathways. These new insights into CNBP functions underscore the essential role of CNBP in forebrain formation during chick embryo organogenesis.

Animals↗

PubMed2006

A novel selective progesterone receptor modulator asoprisnil (J867) down-regulates the expression of EGF, IGF-I, TGFbeta3 and their receptors in cultured uterine leiomyoma cells.

BACKGROUND: This study was conducted to evaluate the effects of a novel selective progesterone receptor modulator (SPRM) asoprisnil on the expression of growth factors and their receptors and on growth factor-induced proliferation of cultured uterine leiomyoma and matching myometrial cells. METHODS: The expression of epidermal growth factor (EGF), insulin-like growth factor-I (IGF-I) and transforming growth factor (TGFbeta3) was assessed by immunocytochemistry and semi-quantitative RT-PCR. The expression of phosphorylated EGF receptor (p-EGFR), IGF-I receptor alpha subunit (IGF-IRalpha) and phosphorylated TGFbeta receptor type II (p-TGFbeta RII) was assessed by Western blot analysis. Cell proliferation was assessed by 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium assay. RESULTS: Treatment with 10(-7) M asoprisnil decreased EGF, IGF-I and TGFbeta3 mRNA and protein expression as well as p-EGFR, IGF-IRalpha and p-TGFbeta RII protein expression in leiomyoma cells cultured for 72 h. EGF (100 ng/ml), IGF-I (100 ng/ml) and TGFbeta3 (10 ng/ml) increased the number of viable leiomyoma cells cultured for 72 h, whereas the concomitant treatment with 10(-7) M asoprisnil antagonized the growth factor-induced increase in leiomyoma cell proliferation. In cultured myometrial cells, however, asoprisnil affected neither the growth factor and their receptor expression nor the cell proliferation. CONCLUSION: Asoprisnil inhibits the expression of EGF, IGF-I, TGFbeta3 and their receptors in cultured leiomyoma cells without affecting their expressions in myometrial cells.

Adult↗

PubMed2006

Concepts in receptor optimization: targeting the RGD peptide.

Synthetic receptors have a wide range of potential applications, but it has been difficult to design low molecular weight receptors that bind ligands with high, "proteinlike" affinities. This study uses novel computational methods to understand why it is hard to design a high-affinity receptor and to explore the limits of affinity, with the bioactive peptide RGD as a model ligand. The M2 modeling method is found to yield excellent agreement with experiment for a known RGD receptor and then is used to analyze a series of receptors generated in silico with a de novo design algorithm. Forces driving binding are found to be systematically opposed by proportionate repulsions due to desolvation and entropy. In particular, strong correlations are found between Coulombic attractions and the electrostatic desolvation penalty and between the mean energy change on binding and the cost in configurational entropy. These correlations help explain why it is hard to achieve high affinity. The change in surface area upon binding is found to correlate poorly with affinity within this series. Measures of receptor efficiency are formulated that summarize how effectively a receptor uses surface area, total energy, and Coulombic energy to achieve affinity. Analysis of the computed efficiencies suggests that a low molecular weight receptor can achieve proteinlike affinity. It is also found that macrocyclization of a receptor can, unexpectedly, increase the entropy cost of binding because the macrocyclic structure further restricts ligand motion.

Models, Molecular↗

PubMed2006

Facile synthesis of polyaniline-sodium alginate nanofibers.

This work demonstrates a facile route to the synthesis of large quantities of uniform polyaniline-sodium alginate (PANI-SA) nanofibers template-guided by SA. This approach is an easy, inexpensive, environmentally friendly, and scalable one-step method to produce uniform nanofibers with controllable average diameters in bulk quantities. We started with biopolymer-monomer complexes formed between the carboxylic groups of SA and the amino group of an organic monomer (aniline). When ammonium persulfate was added, such polymer-monomer complexes could be polymerized. Then, polyaniline-sodium alginate nanofibers with uniform diameters from 40 to 100 nm were successfully obtained in a high yield. The resultant PANI-SA nanofibers were characterized by means of different techniques, such as ultraviolet-visible spectroscopy, thermogravimetric analysis, wide-angle X-ray diffraction, Fourier transform infrared spectroscopy, and scanning and transmission electron microscopy methods. The mechanism governing the formation of the polyaniline-sodium alginate nanofibers is discussed.

Journal Article↗

PubMed2006

Correlates of vascular structure and function measures in asymptomatic young adults: the Bogalusa Heart Study.

BACKGROUND: Adverse changes in arterial structure and function, independent predictors of cardiovascular (CV) disease morbidity and mortality, are known to be associated with CV risk factors, especially in middle-aged and older adults. Although non-invasive studies in this regard are beginning to emerge in a younger age population, information is lacking on the correlates of measures of vascular structure and function obtained simultaneously by different non-invasive methods. METHODS: In 518 black and white subjects (72% white, 44% male) aged 27-43 years, vascular structure and function were measured in terms of (1) carotid artery intima-media thickness (IMT), (2) aorta-femoral pulse wave velocity (af-PWV), and (3) pulsatile arterial function in terms of large (C1) and small (C2) artery compliances. RESULTS: Blacks versus whites and males versus females had higher carotid IMT; blacks versus whites higher af-PWV; and blacks versus whites and females versus males lower C1 and C2. In a multivariate regression model, significant predictors in the order of entry into the model were systolic blood pressure, male gender, age, cigarette smoking, and LDL cholesterol for carotid IMT (R(2)=0.189); systolic blood pressure, homeostasis model assessment of insulin resistance (HOMA-IR), cigarette smoking, and age for af-PWV (R(2)=0.200); systolic blood pressure, female gender, and HOMA-IR for C1 (R(2)=0.258); and systolic blood pressure, female gender, age, diastolic blood pressure, cigarette smoking, triglycerides, and black race for C2 (R(2)=0.394). CONCLUSION: In asymptomatic young adults, CV risk factors influence adversely measures of both structure and function of the vasculature to varying degrees, with small artery compliance showing maximum variance. As part of preventive cardiology, assessment of structure/function measures of the vasculature by simple non-invasive methods may be helpful in identifying early vascular damage in a high-risk young population group.

Adult↗

PubMed2006

A reducing and denaturing step maximizes the immunoprecipitations of m-calpain and I-2(PP2A)/SET: an approach toward antibodies that do not work well in immunoprecipitation.

Immunoprecipitation is an elegant method to isolate a specific protein of interest from a complex protein mixture such as cell lysate. We tried to increase the efficiency of m-calpain immunoprecipitation with anti-m-calpain antibodies directed toward denatured antigens that only work for immunoblotting and immunohistochemistry. We found that a reducing and denaturing step prior to immunoprecipitation greatly potentiates the efficiency of the immunoreaction. This improved method is also applicable for the immunoprecipitation of oncoprotein I-2(PP2A)/SET with antibodies directed toward a synthetic peptide that only work for immunoblotting. Thus, our improved method provides a way to maximize immunoprecipitation when using antibodies that do not work well under conventional immunoprecipitation conditions. Furthermore, the improved method is also suitable for decreasing the contaminating proteins during immunoprecipitation.

Antibodies↗

PubMed2006

Facile autoreduction of iron oxide/carbon nanotube encapsulates.

Facile autoreduction of iron oxide encapsulated within carbon nanotubes has been observed at a temperature 200 degrees C lower than those on the outer surface. This opens a new route to tune the state of confined nanoparticles of d-band metals by the confinement of CNTs.

Journal Article↗

PubMed2006

High-level expression, purification, and characterization of non-tagged Aspergillus flavus urate oxidase in Escherichia coli.

The entire encoding region for Aspergillus flavus uricase was cloned into pET-32a and expressed in Escherichia coli BL21 (DE3). The uricase was expressed in the E. coli cytoplasm in a completely soluble, biologically active form. A scalable process aimed to produce and purify multi-gram quantities of highly pure, recombinant urate oxidase (rUox) from E. coli was developed. The rUox protein was produced in a 30 L fermentor containing 25 L of 2x YT medium and purified to >99% purity using hydrophobic interaction, anion-exchange, and gel filtered chromatography. The final yield of purified rUox from fermentation resulted in approximately 27 g of highly pure, biologically active rUox per kg of cell paste (approximately 238 mg/8.8 g cell paste/L). The results presented here exhibit the ability to generate multi-gram quantities of rUox from E. coli that may be used for the development of pharmaceutics of reducing the hyperuricemia.

Aspergillus flavus↗

PubMed2006

The apoptosis effect of hispolon from Phellinus linteus (Berkeley & Curtis) Teng on human epidermoid KB cells.

Phellinus linteus (Berkeley & Curtis) Teng, a well-known fungus of the genus Phellinus in the family of Hymenochaetaceae, is being increasingly used to treat a wide variety of disease processes such as oral ulcer, gastroenteric disorder, inflammation, lymphatic disease, and various cancers. However, the mechanism underlying its anti-oral cancer effect is poorly understood. In the present study, we prepared the ethanol extract of Phellinus linteus as a crude drug, and then obtained the active component hispolon by bioassay-guided isolation. Hispolon showed a dose-dependent inhibition of human epidermoid KB cell proliferation with IC50 of 4.62+/-0.16 microg/ml. Furthermore, it was revealed that hispolon could induce human epidermoid KB cell apoptosis with the characteristic of a DNA ladder, and with a significant increase of sub-G1. This process was accompanied by the collapse of mitochondrial membrane potential, the release of cytochrome c and the activation of Caspase-3. These results demonstrated that hispolon induced the death of KB cells through a mitochondria mediated apoptotic pathway. We propose that Phellinus linteus and its effective components could be used as an anti-oral cancer drug for future studies.

Apoptosis↗