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Articles by B Liu
Total Records ( 13 ) for B Liu
  B Liu
  Objectives:

To examine the effect of reproductive history and use of hormonal therapies on the risk of hip and knee joint replacement for osteoarthritis.

Methods:

A prospective study of 1.3 million women aged on average 56 years at recruitment and followed-up through linkage to routinely collected hospital admission records was conducted. The adjusted relative risk (RR) of hip and knee replacement for osteoarthritis was examined in relation to parity, age at menarche, menopausal status, age at menopause and use of hormonal therapies.

Results:

Over a mean of 6.1 person-years of follow-up, 12 124 women had a hip replacement and 9977 a knee replacement. The risk of joint replacement increased with increasing parity and the effect was greater for the knee than the hip: increase in RR of 2% (95% CI 1 to 4%) per birth for hip replacement and 8% (95% CI 6 to 10%) for knee replacement. An early age at menarche slightly increased the risk of hip and knee replacement (relative risk for menarche <=11 years versus 12 years, 1.09 (95% CI 1.03 to 1.16) and 1.15 (95% CI 1.08 to 1.22), respectively). Menopausal status and age at menopause were not clearly associated with risk. Current use of postmenopausal hormone therapy was associated with a significant increase in the incidence of hip and knee replacement (RR 1.38 (95% CI 1.30 to 1.46) and RR 1.58 (95% CI 1.48 to 1.69), respectively) while previous use of oral contraceptives was not (RR 1.02 (95% CI 0.98 to 1.06) and RR 1.00 (95% CI 0.96 to 1.04) for hip and knee, respectively).

Conclusions:

Hormonal and reproductive factors affect the risk of hip and knee replacement, more so for the knee than the hip. The reasons for this are unclear.

  S. M Pantanelli , Z Li , R Fariss , S. P Mahesh , B Liu and R. B. Nussenblatt
 

Patients with active posterior and intermediate uveitis have inflammatory cells in their vitreous; those with primary intraocular lymphoma have malignant B-lymphoma cells concomitantly. These cell types cannot be distinguished clinically. The goal of this study was to investigate intrinsic autofluorescence as a noninvasive way of differentiating immune and lymphomatous cell populations. Human primary T cells were stimulated with or without anti-CD3 plus anti-CD28 stimulation. B-lymphoma cells (CA46) were cultured separately. Five experimental groups were prepared: unstimulated T cells, stimulated T cells, CA46 cells, and stimulated T cells mixed with CA46 cells at a ratio of 1:3 or mixed at a ratio of 3:1. Samples were excited with three wavelengths and imaged with a confocal microscope. For each condition, the autofluorescent emissions from the sample were measured. In separate experiments, T cells or CA46 cells were injected into the anterior chamber of a BALB/c mouse eye and autofluorescence was measured. Pure T-cell and lymphoma populations were clearly distinguishable based on autofluorescence intensity spectra. CA46 cells were the least fluorescent when excited with 351-nm light, but most fluorescent when excited with longer wavelengths like 488 nm. Mixed populations of T cells and CA46 cells had emission intensities that fell predictably in between those of the pure populations. An ex vivo study showed that CA46 cells could be detected based on their intrinsic autofluorescence. Our studies showed that normal activated and malignant lymphocyte populations can be distinguished based on their intrinsic autofluorescent properties. Future work with in vivo models may prove useful in facilitating the diagnosis of uveitis and other ocular diseases. [Cancer Res 2009;69(11):4911–7]

  X Yang , S Yang , C McKimmey , B Liu , S. M Edgerton , W Bales , L. T Archer and A. D. Thor
 

Genistein is a major isoflavone with known hormonal and tyrosine kinase-modulating activities. Genistein has been shown to promote the growth of estrogen receptor positive (ER+) MCF-7 cells. In ER-negative (ER–)/erbB-2-overexpressing (erbB-2+) cells, genistein has been shown to inhibit cell growth through its tyrosine kinase inhibitor activity. The effects of genistein on cell growth and tamoxifen response in ER+/erbB-2-altered breast cancers (known as luminal type B and noted in ~10 to 20% of breast cancers) have not been well explored. Using erbB-2-transfected ER+ MCF-7 cells, we found that genistein induced enhanced cellular proliferation and tamoxifen resistance when compared with control MCF-7 cells. These responses were accompanied by increased phosphorylation of ER and ER signaling, without increase in ER protein levels. Genistein-treated MCF-7/erbB-2 cells also showed enhanced activation/phosphorylation of erbB-2, Akt and mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase. Blockade of the phosphatidylinositol 3-kinase and/or MAPK pathways abrogated genistein-induced growth promotion, suggesting that genistein effects involve both critical signaling pathways. We also found that p27/kip1 was markedly downregulated in genistein-treated MCF-7/erbB-2 cells. Overexpression of p27/kip1 attenuated genistein-mediated growth promotion. In aggregate, our data suggest that the concomitant coexpression of ER and erbB-2 makes breast cancers particularly susceptible to the growth-promoting effects of genistein across a wide range of doses. The underlying mechanisms involve enhanced ER–erbB-2 cross talk and p27/kip1 downregulation.

  G. X Li , Y. K Chen , Z Hou , H Xiao , H Jin , G Lu , M. J Lee , B Liu , F Guan , Z Yang , A Yu and C. S. Yang
 

(–)-Epigallocatechin-3-gallate (EGCG), the major polyphenol in green tea, has been shown to inhibit tumorigenesis and cancer cell growth in animal models. Nevertheless, the dose–response relationship of the inhibitory activity in vivo has not been systematically characterized. The present studies were conducted to address these issues, as well as the involvement of reactive oxygen species (ROS), in the inhibitory action of EGCG in vivo and in vitro. We characterized the inhibitory actions of EGCG against human lung cancer H1299 cells in culture and in xenograft tumors. The growth of tumors was dose dependently inhibited by EGCG at doses of 0.1, 0.3 and 0.5% in the diet. Tumor cell apoptosis and oxidative DNA damage, assessed by the formation of 8-hydroxy-2'-deoxyguanosine (8-OHdG) and phosphorylated histone 2A variant X (-H2AX), were dose dependently increased by EGCG treatment. However, the levels of 8-OHdG and -H2AX were not changed by the EGCG treatment in host organs. In culture, the growth of viable H1299 cells was dose dependently reduced by EGCG; the estimated concentration that causes 50% inhibition (IC50) (20 µM) was much higher than the IC50 (0.15 µM) observed in vivo. The action of EGCG was mostly abolished by the presence of superoxide dismutase (SOD) and catalase, which decompose the ROS formed in the culture medium. Treatment with EGCG also caused the generation of intracellular ROS and mitochondrial ROS. Although EGCG is generally considered to be an antioxidant, the present study demonstrates the pro-oxidative activities of EGCG in vivo and in vitro in the described experimental system.

  B Liu , D Chen , L Yang , Y Li , X Ling , L Liu , W Ji , Y Wei , J Wang , Q Wei , L Wang and J. Lu
 

Mitogen-activated protein kinase kinase 4 (MKK4) is a critical mediator of stress-activated protein kinase signals that regulate apoptosis, inflammations and tumorigenesis. Several polymorphisms have been identified in the MKK4 gene. We hypothesized that genetic variants in the MKK4 promoter may alter its expression and thus cancer risk. In a case–control study of 1056 lung cancer cases and 1056 sex and age frequency-matched cancer-free controls, we genotyped two common polymorphisms in the MKK4 promoter region (–1304T>G and –1044A>T) with the Taqman assay, and we found that compared with the most common –1304TT genotype, carriers of –1304G variant genotypes had a decreased risk of lung cancer [odds ratio (OR) = 0.74; 95% confidence interval (CI) = 0.61–0.90 for TG, and OR = 0.62; 95% CI = 0.41–0.94 for GG] in an allele dose–response manner (adjusted Ptrend = 0.0005). Further stratification analysis showed that the protective role of the –1304G variant allele was more evident in low or normal body mass index (BMI) but restrained in the overweighters and that the –1304G variant genotypes interacted with BMI in reducing cancer risk (adjusted Pinteraction = 0.003). Moreover, the luciferase assay showed that the G allele in the promoter significantly increased the transcription activity of the MKK4 gene in vitro and that the MKK4 protein expression levels of the G variant carriers was significantly higher in tumor tissues than those of the –1304TT genotype. However, no significant association was observed between the –1044A>T polymorphism and risk of lung cancer. Our data suggest that the functional –1304G variant in the MKK4 promoter contributes to a decreased risk of lung cancer by increasing the promoter activity and that the G variant may be a marker for susceptibility to lung cancer.

  L Wang , J Zheng , Y Du , Y Huang , J Li , B Liu , C. j Liu , Y Zhu , Y Gao , Q Xu , W Kong and X. Wang
 

Rational: Vascular smooth muscle cells (VSMCs) switching from a contractile/differentiated to a synthetic/dedifferentiated phenotype has an essential role in atherosclerosis, postangioplastic restenosis and hypertension. However, how normal VSMCs maintain the differentiated state is less understood.

Objective: We aimed to indentify the effect of cartilage oligomeric matrix protein (COMP), a normal vascular extracellular matrix, on modulation of VSMCs phenotype.

Methods and Results: We demonstrated that COMP was associated positively with the expression of VSMC differentiation marker genes during phenotype transition. Knockdown of COMP by small interfering (si)RNA favored dedifferentiation. Conversely, adenoviral overexpression of COMP markedly suppressed platelet-derived growth factor-BB-elicited VSMC dedifferentiation, characterized by altered VSMC morphology, actin fiber organization, focal adhesion assembly, and the expression of phenotype-dependent markers. Whereas 7 integrin coimmunoprecipitated with COMP in normal rat VSMCs and vessels, neutralizing antibody or siRNA against 7 integrin inhibited VSMC adhesion to COMP, which indicated that 7β1 integrin is a potential receptor for COMP. As well, blocking or interference by siRNA of 7 integrin completely abolished the effect of COMP on conserving the contractile phenotype. In accordance, ectopic adenoviral overexpression of COMP greatly retarded VSMC phenotype switching, rescued contractility of carotid artery ring, and inhibited neointima formation in balloon-injured rats.

Conclusions: Our data suggest that COMP is essential for maintaining a VSMC contractile phenotype and the protective effects of COMP are mainly mediated through interaction with 7β1 integrin. Investigations to identify the factors affecting the expression and integrity of COMP may provide a novel therapeutic target for vascular disorders.

  B Liu , A. V Perepelov , M. V Svensson , S. D Shevelev , D Guo , S. N Senchenkova , A. S Shashkov , A Weintraub , L Feng , G Widmalm , Y. A Knirel and L. Wang
 

O-antigen (O-polysaccharide), a part of the outer membrane of Gram-negative bacteria, is one of the most variable cell constituents and is related to bacterial virulence. O-antigen diversity is almost entirely due to genetic variations in O-antigen gene clusters. In this study, the O-polysaccharide structures of Salmonella O55 and Escherichia coli O103 were elucidated by chemical analysis and nuclear magnetic resonance spectroscopy. It was found that the O-polysaccharides have similar pentasaccharide O-units, which differ only in one sugar (glucose versus N-acetylglucosamine) and in the N-acyl group (acetyl versus 3-hydroxybutanoyl) on 3-amino-3,6-dideoxy-d-galactose (d-Fuc3N). The Salmonella O55 antigen gene cluster was sequenced and compared with the E. coli O103 antigen gene cluster reported previously. The two gene clusters were found to share high-level similarity (DNA identity ranges from 53% to 76%), except for two putative acyl transferase genes (fdtC in Salmonella O55 and fdhC in E. coli O103) which show no similarity. Replacement of the fdtC gene in Salmonella O55 with the fdhC gene from E. coli O103 resulted in production of a modified O-antigen, which contains a 3-hydroxybutanoyl derivative of Fuc3N in place of 3-acetamido-3,6-dideoxygalactose. This finding strongly suggests that fdhC is a 3-hydroxybutanoyltransferase gene. The sequence similarity level suggested that the O-antigen gene clusters of Salmonella O55 and E. coli O103 originate from a common ancestor, and this evolutionary relationship is discussed.

  P Liu , W Chen , H Zhu , B Liu , S Song , W Shen , F Wang , S Tucker , B Zhong and D. Wang
  Objective

The purpose of this study was to specifically investigate the clinicopathological role of expression of vascular endothelial growth factor-C (VEGF-C) as well as the correlation with clinical outcomes in esophageal squamous cell carcinomas (ESCCs).

Methods

Seventy-three patients with ESCC resected in our institute were included in this study. Formalin-fixed paraffin-embedded specimens were stained for VEGF-C and the correlation between the staining, its clinicopathological parameters and its prognostic power were analyzed statistically.

Results

Of the 73 ESCC patients studied, 39 cases (53.4%) were strongly positive for VEGF-C. Six cases (8.2%) were negative and 28 cases (38.4%) revealed unclear weak reactions. All 34 cases were included in the negative group (46.6%). VEGF-C expression correlated with histological grade (P = 0.005), depth of tumor invasion (pT) (P = 0.021), lymph node metastasis (pN) (P = 0.002) and lymphatic invasion (P = 0.008). The median overall survival of 39 patients who had positive staining for tumor cell VEGF-C and 34 patients who had negative staining were 10.4 months (95% CI, 6.9–13.9 months) and 28.5 months (95% CI, 12.6–44.4 months), respectively (P = 0.003). In univariate analysis by log-rank test, histological grade, pN, stage, lymphatic invasion and VEGF-C were significant prognostic factors (P = 0.047, 0.007, 0.018, 0.002 and 0.003, respectively.). In multivariate analysis, high VEGF-C expression (P = 0.0451) maintained its independent prognostic influence on overall survival, as well as pN status (P = 0.0029).

Conclusions

Expression of VEGF-C is related to histological grade, pT, pN and lymphatic invasion, and is a prognostic indicator for ESCC.

  B Liu and J. Abe
 

The insensitivity of flowering to long daylength is an important characteristic which soybeans have used to adapt to environments at higher latitude. The objective of this study was to map the novel gene(s) for photoperiod insensitivity in the Japanese soybean landrace Sakamotowase. A previous study suggested that Sakamotowase possessed the genotype e1e1e3e3E4E4. The progeny of testcrosses with the Harosoy isoline for e3 (L62-667) produced the roughly expected segregation pattern for the monogenic inheritance, suggesting the major involvement of a single gene in photoperiod insensitivity of Sakamotowase. By mapping analysis for 6 linkage groups (LGs) harboring the known major genes and quantitative trait loci (QTLs) for flowering, we detected a major QTL for the insensitivity near an simple sequence repeat marker (Satt577) in LG C2 and a minor QTL in LG L. Our results therefore suggest that a novel gene for photoperiod insensitivity of Sakamotowase was located in LG C2. It was estimated from the position of the tagging marker that the novel gene may be an allele at the E1 or E7 loci or a novel gene tightly linked to the E1 locus.

  J Liu , Y Song , B Tian , J Qian , Y Dong , B Liu and Z. Sun
 

It is well established that promyelocytic leukaemia nuclear bodies (PML NBs) play important roles in DNA damage responses (DDR). After irradiation, PML NBs dynamically recruit or release important proteins involved in cell-cycle regulation, DNA repair and apoptosis. As PML protein is the key molecule of PML NBs’ dynamic assembling, we aimed to characterize the PML-interacting proteins in 60Co-irradiated MCF-7 cells. A proteomic approach using CoIP, mono-dimensional electrophoresis and tandem mass spectrometry, allowed us to identify a total of 124 proteins that may associate with PML after irradiation. Bioinformatic analysis of the identified proteins showed that most of them were related to characterized PML functions, such as transcriptional regulation, cell-cycle regulation, cell-death regulation and response to stress. Four proteins, B23, MVP, G3BP1 and DHX9, were verified to co-localize with PML differentially before and after ionizing radiation (IR) treatment. The proteins identified in this study will significantly improve our understanding of the dynamic organization and multiple functions of PML NBs in DDR.

  F Zhang , S Tsai , K Kato , D Yamanouchi , C Wang , S Rafii , B Liu and K. C. Kent
 

Bone marrow-derived progenitor cells have recently been shown to be involved in the development of intimal hyperplasia after vascular injury. Transforming growth factor-β (TGF-β) has profound stimulatory effects on intimal hyperplasia, but it is unknown whether these effects involve progenitor cell recruitment. In this study we found that although TGF-β had no direct effect on progenitor cell recruitment, conditioned media derived from vascular smooth muscle cells (VSMC) stimulated with TGF-β induced migration of both total bone marrow (BM) cells and BM-mesenchymal stem cells (MSC) and also induced MSC differentiation into smooth muscle like cells. Furthermore, overexpression of the signaling molecule Smad3 in VSMC via adenovirus-mediated gene transfer (AdSmad3) enhanced the TGF-β's chemotactic effect. Microarray analysis of VSMC stimulated by TGF-β/AdSmad3 revealed monocyte chemoattractant protein-1 (MCP-1) as a likely factor responsible for progenitor cell recruitment. We then demonstrated that TGF-β through Smad3 phosphorylation induced a robust expression of MCP-1 in VSMC. Recombinant MCP-1 mimicked the stimulatory effect of conditioned media on BM and MSC migration. In the rat carotid injury model, Smad3 overexpression significantly increased MCP-1 expression after vascular injury, consistent with our in vitro results. Interestingly, TGF-β/Smad3-induced MCP-1 was completely blocked by both Ro-32-0432 and rotterlin, suggesting protein kinase C- (PKC) may play a role in TGF-β/Smad3-induced MCP-1 expression. In summary, our data demonstrate that TGF-β, through Smad3 and PKC, stimulates VSMC production of MCP-1, which is a chemoattractant for bone marrow-derived cells, specifically MSC. Manipulation of this signaling system may provide a novel approach to inhibition of intimal hyperplasia.

  B Liu , J Yao , Y Wang , H Li and F. Qin
 

Protons, which are released during inflammation and injury, regulate many receptors and ion channels involved in pain transduction, including capsaicin channels (transient receptor potential vanilloid receptors 1). Whereas extracellular acidification both sensitizes and directly activates the channel, it also causes concomitant reduction of the unitary current amplitudes. Here, we investigate the mechanisms and molecular basis of this inhibitory effect of protons on channel conductance. Single-channel recordings showed that the unitary current amplitudes decreased with extracellular pH in a dose-dependent manner, consistent with a model in which protons bind to a site within the channel with an apparent pKa of ~6. The inhibition was voltage dependent, ~65% at –60 mV and 37% at +60 mV when pH was reduced from 7.4 to 5.5. The unitary current amplitudes reached saturation at [K+] ≥ 1 M, and notably the maximum amplitudes did not converge with different pHs, inconsistent with a blockade model based on surface charge screening or competitive inhibition of permeating ions. Mutagenesis experiments uncovered two acidic residues critical for proton inhibition, one located at the pore entrance and the other on the pore helix. Based on homology to the KcsA structure, the two acidic residues, along with another basic residue also on the pore helix, could form a triad interacting with each other through extensive hydrogen bonds and electrostatic contacts, suggesting that protons may mediate the interactions between the selectivity filter and pore helix, thereby altering the local structure in the filter region and consequently the conductance of the channel.

 
 
 
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