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Yao Wang

Publications and source records attributed to Yao Wang.

50 records · Page 3Linked to original sources
PubMed2003

Proteomic profiling of proteins associated with urokinase plasminogen activator receptor in a colon cancer cell line using an antisense approach.

Expression of urokinase plasminogen activator (uPA) and its receptor (uPAR) strongly correlates with a malignant tumour cell phenotype. In the multistep process of metastasis, uPA binding to uPAR influences different cellular functions. In the present study, a highly metastatic colon cancer cell line, HCT116 was transfected with an expression vector containing a 5' uPAR cDNA fragment in an antisense orientation. This construct was most effective in reducing uPAR cell surface expression as confirmed by flow cytometry analysis. Antisense transfection of HCT116 cells had no effect on proliferation but the following effects were observed: (1) a 1.3-fold decreased adhesion; (2) a two-fold decreased Erk MAP kinase activity; (3) a 2.7-fold decrease in Src kinase activity; (4) a 1.5- and two-fold decrease in uPA cell surface expression and secretion; (5) abrogation of promatrix metalloproteinase-9 secretion; and (6) a complete suppression of plasminogen-dependent matrix degradation. Using proteomic analysis, we demonstrate loss of approximately 200 proteins and quantitative differences in the expression of 141 other proteins in an antisense-clone compared to wild-type and mock-transfected control. Such changes in protein expression with the down-regulation of uPAR may be an important contributor in colon cancer progression and metastasis and may not only provide a basis to develop a proteomic data bank of uPAR-mediated signaling molecules but may also lead to the development of therapeutic approaches for the cure and better management of colon cancer.

5' Untranslated Regions↗
PubMed2003

Transgenic mice demonstrate novel promoter regions for tissue-specific expression of the urokinase receptor gene.

The urokinase-type plasminogen activator receptor (u-PAR) contributes to cell migration and proteolysis in normal and cancerous tissues. Currently, there are no reports on the regulatory regions directing tissue-specific expression. Consequently, we undertook a study to identify novel promoter regions required for expression of this gene in transgenic mice bearing a LacZ reporter regulated by varying amounts (0.4, 1.5, and 8.5 kb) of upstream sequence. The 0.4-kb u-PAR upstream sequence directed weak and strong LacZ expression in the placenta and epididymis, respectively, both of which are tissues that express endogenous u-PAR. Conversely, transgene expression in the apical cells of the colon positive for endogenous u-PAR protein required 1.5 kb of upstream sequence for optimal expression. Furthermore, chromatin accessibility assays coupled with real-time polymerase chain reaction suggested a putative regulatory region spanning -1295/-1192 driving u-PAR expression in colonic cells. Interestingly, placental transgene expression was augmented with the 8.5-kb upstream fragment compared with the shorter 1.5-kb fragment indicating contributing element(s) between -1.5 and -8.5 kb. Thus, while 0.4 kb of upstream sequence directs u-PAR expression in the epididymis, sequences located between -0.4 and -1.5 kb and between -1.5 and -8.5 kb are required for optimal tissue-specific expression in the colon and the placenta, respectively.

Animals↗
PubMed2003

Adenovirus-mediated gene transfer to healing tendon--enhanced efficiency using a gelatin sponge.

Adenovirus-mediated gene transfer is a potential method for enhancing tendon healing. We investigated the transfection of Ad5CMVntLacZ, an adenovirus containing the reporter gene LacZ, in primary cultured human rotator cuff tendon cells and in a rat Achilles tendon healing model in vivo. Ad5CMVempty, the adenoviral vector containing no inserted gene, was used as a control for adenoviral transfection alone. Activity of beta-galactosidase,the protein expressed by LacZ gene, was measured using a beta-galactosidase assay and detected visually by X-gal staining. Cultured cells were successfully transfected without impairing cell viability. Maximal beta-galactosidase activity was detected when cells were transfected at the dose of 1000 PFU/cell. The duration of LacZ expression was six days with a peak value at 24 h post-transfection. A transfection rate of 100% was obtained at 5000 PFU/cell. Successful in vivo transfection by Ad5CMVntLacZ was obtained in healing rat Achilles tendon as confirmed by X-gal staining. 0.4% of tendon cells were transfected when Ad5CMVntLacZ was injected into the tendon at a dose of 10(6) PFU. The rate rose to 2% with 10(8) PFU and 3% with 10(9) PFU. The duration of LacZ expression in vivo was 17 days. Transfection efficiency was enhanced threefold and localization improved when a gelatin sponge was used to deliver the adenovirus. The results demonstrate that adenovirus can be used to deliver a gene of interest to cultured human rotator cuff tendon cells and healing tendon, with gelatin sponge implantation enhancing adenoviral transfection efficiency in vivo.

Achilles Tendon↗
PubMed2003

Expression of urokinase-type plasminogen activator and its receptor is up-regulated during tendon healing.

The urokinase-type plasminogen activator (uPA) system has been implicated in cell migration, angiogenesis, extracellular matrix synthesis and tissue remodelling. However, little is known about the role of the system in tendon healing. We used a rat Achilles tendon model to study mRNA and protein expression of uPA and its receptor (uPAR) during tendon healing using immunohistochemical, Northern and Western blot analyses. Time-dependent increases in uPA/uPAR mRNAs and proteins, maximal on days 4-7 and 7-14 respectively, were found following Achilles tendon division. Interestingly, uninjured control tendons expressed uPA mRNA and protein, but little uPAR transcripts and protein. On day 14 following Achilles tendon division, uPA receptor protein increased 12.6-fold (p<0.001) while uPA itself increased only 1.3-fold (p<0.05). Immunohistochemical analyses revealed that both uPAR/uPA positive staining cells were increased in the healing tendon tissue section. These findings show for the first time that uPA, and especially its receptor uPAR, are up-regulated during tendon healing.

Achilles Tendon↗
PubMed2003

Notes on synthetic phased-array with 2-D sparse arrays.

Recent advances in 3-dimensional (3-D) imaging with 2-D sparse arrays have generated renewed interest in array synthesis theory. The 3-D imaging with arbitrary planar line shapes is particularly interesting. In this correspondence, we clarify some points presented in recent publications and show that aperture synthesis can be viewed with a very simple, physical approach. Its limitations due to approximations also will be discussed.

Computer-Aided Design↗
PubMed2003

Coded excitation with spectrum inversion (CEXSI) for ultrasound array imaging.

In this paper, a scheme called coded excitation with spectrum inversion (CEXSI) is presented. An established optimal binary code whose spectrum has no nulls and possesses the least variation is encoded as a burst for transmission. Using this optimal code, the decoding filter can be derived directly from its inverse spectrum. Various transmission techniques can be used to improve energy coupling within the system pass-band. We demonstrate its potential to achieve excellent decoding with very low (< 80 dB) side-lobes. For a 2.6 micros code, an array element with a center frequency of 10 MHz and fractional bandwidth of 38%, range side-lobes of about 40 dB have been achieved experimentally with little compromise in range resolution. The signal-to-noise ratio (SNR) improvement also has been characterized at about 14 dB. Along with simulations and experimental data, we present a formulation of the scheme, according to which CEXSI can be extended to improve SNR in sparse array imaging in general.

Algorithms↗
PubMed2003

Peptide models of four possible insulin folding intermediates with two disulfides.

The single-chain insulin (PIP) can spontaneously fold into native structure through preferred kinetic intermediates. During refolding, pairing of the first disulfide A20-B19 is highly specific, whereas pairing of the second disulfide is likely random because two two-disulfide intermediates have been trapped. To get more details of pairing property of the second disulfide, four model peptides of possible folding intermediates with two disulfides were prepared by protein engineering, and their properties were analyzed. The four model peptides were named [A20-B19, A7-B7]PIP, [A20-B19, A6-B7]PIP, [A20-B19, A6-A11]PIP, and [A20-B19, A7-A11]PIP according to their remaining disulfides. The four model peptides all adopt partially folded structure with moderate conformational differences. In redox buffer, the disulfides of the model peptides are more easily reduced than those of the wild-type PIP. During in vitro refolding, the reduced model peptides share similar relative folding rates but different folding yields: The refolding efficiency of the reduced [A20-B19, A7-A11]PIP is about threefold lower than that of the other three peptides. The present results indicate that the folding intermediates corresponding to the present model peptides all adopt partially folded conformation, and can be formed during PIP refolding, but the chance of forming the intermediate with disulfide [A20-B19, A7-A11] is much lower than that of forming the other three intermediates.

Chromatography, High Pressure Liquid↗
PubMed2003

Subcellular localization of feline immunodeficiency virus integrase and mapping of its karyophilic determinant.

Feline immunodeficiency virus (FIV), like other members of the lentivirus subfamily, such as human immunodeficiency virus type 1 (HIV-1), can infect nondividing and terminally differentiated cells. The transport of the preintegration complex into the nucleus is cell cycle-independent, but the mechanism is not well understood. Integrase is a key component of the complex and has been suggested to play a role in nuclear import during HIV-1 replication. To determine its karyophilic property, FIV integrase fused with glutathione S-transferase and enhanced green fluorescent protein was expressed in various feline and human cells and the subcellular localization was visualized by fluorescence microscopy. Wild-type FIV integrase was karyophilic in all cell lines tested and capable of targeting the fusion protein to the nuclei of transfected cells. Analysis of deletion and point mutation variants of FIV integrase failed to reveal any canonical nuclear localization signal, and the karyophilic determinant was mapped to the highly conserved N-terminal zinc-binding HHCC motif. A region near the C-terminal domain enriched with basic amino acid residues also affected the nuclear import of integrase. However, the role of this region is only modulatory in comparison to that of the zinc-binding domain. The N-terminal zinc-binding domain does not bind DNA and instead is essential in integrase multimerization. We therefore postulate that the karyophilic property of FIV integrase requires subunit multimerization promoted by the HHCC motif. Alternatively, the HHCC motif may directly promote interaction between FIV integrase and cellular proteins involved in nuclear import.

Animals↗
PubMed2003

The roles of growth factors in tendon and ligament healing.

Tendon healing is a complex and highly-regulated process that is initiated, sustained and eventually terminated by a large number and variety of molecules. Growth factors represent one of the most important of the molecular families involved in healing, and a considerable number of studies have been undertaken in an effort to elucidate their many functions. This review covers some of the recent investigations into the roles of five growth factors whose activities have been best characterised during tendon healing: insulin-like growth factor-I (IGF-I), transforming growth factor beta (TGFbeta), vascular endothelial growth factor (VEGF), platelet-derived growth factor (PDGF), and basic fibroblast growth factor (bFGF). All five are markedly up-regulated following tendon injury and are active at multiple stages of the healing process. IGF-I has been shown to be highly expressed during the early inflammatory phase in a number of animal tendon healing models, and appears to aid in the proliferation and migration of fibroblasts and to subsequently increase collagen production. TGFbeta is also active during inflammation, and has a variety of effects including the regulation of cellular migration and proliferation, and fibronectin binding interactions. VEGF is produced at its highest levels only after the inflammatory phase, at which time it is a powerful stimulator of angiogenesis. PDGF is produced shortly after tendon damage and helps to stimulate the production of other growth factors, including IGF-I, and has roles in tissue remodelling. In vitro and in vivo studies have shown that bFGF is both a powerful stimulator of angiogenesis and a regulator of cellular migration and proliferation. This review also covers some of the most recent studies into the use of these molecules as therapeutic agents to increase the efficacy and efficiency of tendon and ligament healing. Studies into the effects of the exogenous application of TGFbeta, IGF-I, PDGF and bFGF into the wound site singly and in combination have shown promise, significantly decreasing a number of parameters used to define the functional deficit of a healing tendon. Application of IGF-I has been shown to increase in the Achilles Functional Index and the breaking energy of injured rat tendon. TGFbeta and PDGF have been shown separately to increase the breaking energy of healing tendon. Finally, application of bFGF has been shown to promote cellular proliferation and collagen synthesis in vivo.

Animals↗
PubMed2002

Interferon-alpha (Intron A) upregulates urokinase-type plasminogen activator receptor gene expression.

The regulation of urokinase plasminogen activator receptor (uPAR) gene expression by interferon-alpha (IFN-alpha, or Intron A) and interferon-gamma (IFN-gamma) was studied in a HCT116 colon cancer cell line. uPAR mRNA levels were increased in a dose- and time-dependent manner in cells stimulated with IFN-alpha or IFN-gamma. uPAR protein levels reflected IFN-alpha and IFN-gamma induction of uPAR mRNA production. Cycloheximide, a protein synthesis inhibitor, also induced uPAR mRNA accumulation either alone or in combination with IFN-alpha or IFN-gamma, suggesting that the effect on uPAR mRNA levels activated by IFN-alpha or IFN-gamma does not require de novo protein synthesis. Both sodium butyrate and amiloride inhibited the uPAR mRNA levels induced by IFN-alpha or IFN-gamma. These results may provide useful information for the treatment of patients receiving IFN-alpha or IFN-gamma.

Amiloride↗
PubMed2002

Elevated plasma 4-pyridoxic acid in renal insufficiency.

BACKGROUND: Renal insufficiency is associated with altered vitamin B-6 metabolism. We have observed high concentrations of 4-pyridoxic acid, the major catabolite of vitamin B-6 metabolism, in plasma during renal insufficiency. OBJECTIVE: The objective was to evaluate the renal handling of 4-pyridoxic acid and the effects of renal dysfunction on vitamin B-6 metabolism. DESIGN: We measured the renal clearance of 4-pyridoxic acid and creatinine in 17 nonpregnant, 17 pregnant, and 16 lactating women. We then examined the influence of vitamin B-6 or alkaline phosphatase activity on the ratio of 4-pyridoxic acid to pyridoxal (PA:PL) in plasma in 10 men receiving a low (0.4 mg pyridoxine.HCl/d) or high (200 mg pyridoxine.HCl/d) vitamin B-6 intake for 6 wk, in 10 healthy subjects during a 21-d fast, in 1235 plasma samples from 799 people screened for hypophosphatasia, and in 67 subjects with a range of serum creatinine concentrations. RESULTS: Renal clearance of 4-pyridoxic acid was 232 +/- 94 mL/min in nonpregnant women, 337 +/- 140 mL/min in pregnant women, and 215 +/- 103 mL/min in lactating healthy women. These values were approximately twice the creatinine clearance, indicating that 4-pyridoxic acid is at least partially eliminated by tubular secretion. Elevated plasma creatinine concentrations were associated with marked elevations in 4-pyridoxic acid and PA:PL. PA:PL was not affected by wide variations in vitamin B-6 intake or by the wide range of pyridoxal-P concentrations encountered while screening for hypophosphatasia. CONCLUSIONS: Plasma 4-pyridoxic acid concentrations are markedly elevated in renal insufficiency. Plasma PA:PL can distinguish between increases in 4-pyridoxic acid concentrations due to increased dietary intake and those due to renal insufficiency.

Adult↗
PubMed2002

Optimizing the beam pattern of a forward-viewing ring-annular ultrasound array for intravascular imaging.

Intravascular ultrasound (IVUS) imaging systems using circumferential arrays mounted on cardiac catheter tips fire beams orthogonal to the principal axis of the catheter. The system produces high resolution cross-sectional images but must be guided by conventional angioscopy. A real-time forward-viewing array, integrated into the same catheter, could greatly reduce radiation exposure by decreasing angiographic guidance. Unfortunately, the mounting requirement of a catheter guide wire prohibits a full-disk imaging aperture. Given only an annulus of array elements, prior theoretical investigations have only considered a circular ring of point transceivers and focusing strategies using all elements in the highly dense array, both impractical assumptions. In this paper, we consider a practical array geometry and signal processing architecture for a forward-viewing IVUS system. Our specific design uses a total of 210 transceiver firings with synthetic reconstruction for a given 3-D image frame. Simulation results demonstrate this design can achieve side-lobes under -40 dB for on-axis situations and under -30 dB for steering to the edge of a 80 degrees cone.

Blood Vessels↗
PubMed2002

Nephron endowment and renal filtration surface area in young spontaneously hypertensive rats.

BACKGROUND/AIMS: A reduction in nephron endowment leading to reduced renal filtration surface area has been implicated in the development of hypertension. The aim of this study was to compare glomerular (and thereby nephron) number and renal filtration surface area in young Wistar-Kyoto rats (WKY) with young spontaneously hypertensive rats (SHR), prior to the development of hypertension in this model. METHODS: Using unbiased stereological methods the number and size of glomeruli, as well as total renal filtration surface area were determined in perfusion-fixed kidneys of 4-week-old WKY and SHR. RESULTS: At 4 weeks of age, in weight-matched animals, there was no significant difference in the number of glomeruli in the kidneys of SHR compared to WKY (28,620 +/- 1,643 and 25,670 +/- 1,263 glomeruli/kidney, respectively). Similarly, there was no difference in mean glomerular volume (SHR: 4.70 +/- 0.31 x 10(-4) mm(3); WKY: 4.28 +/- 0.20 x 10(-4) mm(3)). Surprisingly, total renal filtration surface area was significantly greater in SHR than WKY (3,867 +/- 116 and 3,176 +/- 83 mm(2), respectively). CONCLUSION: The renal abnormality underlying the development of hypertension in the SHR is not due to inborn deficits in nephron endowment and/or filtration surface area.

Aging↗