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Chen Liu

Publications and source records attributed to Chen Liu.

88 records · Page 5Linked to original sources
PubMed2003

Interleukin-1 inhibits hepatitis C virus subgenomic RNA replication by activation of extracellular regulated kinase pathway.

Interleukin-1 (IL-1) plays an important role in the inflammatory process. Some studies have demonstrated that IL-1 production was impaired in patients with chronic infections of hepatitis C virus (HCV), implying that IL-1 may play a role in viral clearance. Using an HCV subgenomic replicon cell line, we demonstrate that IL-1 can effectively inhibit HCV subgenomic RNA replication and viral protein expression, suggesting that IL-1 has direct antiviral activity. The inhibitory effect is associated with the extracellular regulatory kinase (ERK) activation. In addition, we also show that IL-1 can induce one of the interferon-stimulated genes (ISGs), 1-8U, which exhibits antiviral activity. However, it has no effect on the other ISG, 6-16, suggesting that IL-1 induces novel antiviral pathways within a cell.

Enzyme Activation↗
PubMed2003

beta-Catenin is expressed aberrantly in tumors expressing shadow cells. Pilomatricoma, craniopharyngioma, and calcifying odontogenic cyst.

We studied the beta-catenin immunohistochemical profile in tumors expressing shadow cells: pilomatricoma, 10 cases; calcifying odontogenic cyst, 6 cases; and craniopharyngioma, 9 cases. There was strong membranous, cytoplasmic, and nuclear staining of the immature basaloid cells in all of these tumors. Shadow cells were negative in all tumors. It has been documented that rising levels of free beta-catenin drive the formation of complexes with T-cell factor/lymphoid enhancer factor (TCF-Lef) and up-regulate the wingless-Wnt cell-cell signals. The end result is an abnormality of beta-catenin degradation and, thus, a buildup of free beta-catenin in the cytoplasm and/or nucleus, resulting in the stimulation of cellular proliferation and/or inhibition of cell death. beta-Catenin seems to have an important role in the oncogenesis of these tumors. The similar pattern of keratinization in these tumors and the similar pattern of beta-catenin immunoreactivity in the cytoplasm and the nucleus are important findings. It seems that the activation of a common cellular pathway, namely Wnt-beta-catenin-TCF-Lef, has a role in the pathogenesis of these tumors. The latter could be related to their shared method of keratinization or shared dysfunction of the cellular adhesion complex leading to tumorigenesis.

Craniopharyngioma↗
PubMed2003

[Study on diagnosis of cerebral cysticercosis by antibody detection and imaging techniques].

OBJECTIVE: To establish new criteria of antibody detection for the diagnosis of cerebral cysticercosis in combining with imaging examinations for reducing the missed and neglected diagnosis of the disease. METHODS: 1,160 cases with adequate clinical data were collected for the study, among them all cases received antibody detection and computerized tomography(CT), 538 cases were examined by magnetic resonance imaging(MRI). Following the locations that cysticerci parasitized, the cases were grouped in four types of cerebral cysticercosis: 1,087 cases in brain parenchyma (93.7%), 42 cases in brain ventricles (3.6%), 22 cases in brain meninges (1.9%), and 9 mixed cases (0.8%). According to the number of cysticerci showed by imaging analysis, cases involving parenchyma were further divided as subgroups of slight, moderate, and heavy infection with 1-2, 3-9 and over 10 parasites, with 552 cases(50.8%), 443 cases (39.8%) and 102 cases (9.4%) respectively. IHA and ELISA were used for detecting antibodies in the sera. RESULTS: 635 cases showed an IHA titer of 1:8 and above (54.7%), 700 cases (60.3%) showed positive ELISA and 460 cases (39.7%) showed weak positive. In the group of light infection (552 cases), 94.7% showed an IHA titer of less than 1:8, only 29 cases (5.3%) with a titer of 1:8 and above; 94 cases (17%) showed positive ELISA and 458 cases (83%) were weak positive. In the groups of moderate and heavy infections, all cases showed IHA titer of 1:8 and over, and positive or weak positive ELISA. CONCLUSION: Antibody titers are positively relevant to the intensity of Cysticercus infection. Most cases with light infection showed a low IHA titer (less than 1:8) and a weak positive ELISA, a fact that these cases would have been missed by the immunological tests. Therefore, an integrated analysis of the results with immunological test and clinical imaging technique is important in diagnosing cerebral cysticercosis.

Adolescent↗
PubMed2002

Pretreatment of donors with interleukin-18 attenuates acute graft-versus-host disease via STAT6 and preserves graft-versus-leukemia effects.

Interleukin-18 (IL-18) is a unique cytokine that modulates both T(H)1/T(H)2 responses, but its ability to modulate diseases through induction of T(H)2 cytokines is unclear. It has been shown to play an important role in allogeneic bone marrow transplantation (BMT). Because immune responses of allogeneic BM donors may affect acute graft-versus-host disease (GVHD), we investigated the effect of pretreating BM transplant donors with IL-18 on the severity of acute GVHD using a well-characterized experimental BMT model (BALB/c-->B6). Pretreatment of allogeneic BM transplant donors with IL-18 significantly improved survival (80% vs 0%; P <.001), and reduced clinical, biochemical, and pathologic indices of acute GVHD in BM transplant recipients. IL-18 pretreatment was associated with reduced interferon gamma (IFN-gamma) and greater IL-4 secretion by donor T cells after BMT. Acute GVHD mortality was reduced when IL-18 was administered to donors deficient in IFN-gamma and signal transducer and activator of transcription 4 (STAT4) but not STAT6 signaling molecules, suggesting a critical role for STAT6 signaling in IL-18's protective effect. IL-18 treatment did not alter donor CD8(+) cytotoxic T-lymphocyte (CTL) activity and preserved graft-versus-leukemia (GVL) effects after allogeneic BMT (70% vs 10%; P <.01). Together these data illustrate that pretreatment of donors with IL-18 prior to allogeneic BMT attenuates acute GVHD in a STAT6-dependent mechanism while preserving GVL effects.

Acute Disease↗
PubMed2002

Phage-displayed random peptide libraries in mice: toxicity after serial panning.

PURPOSE: In vivo screening of phage-displayed random peptide libraries (RPLs) has been used to identify peptide ligands to targets found on endothelial cells of blood vessels supplying specific tissues such as brain, kidney, and tumor tissue. Peptides that bind specifically to blood vessels supplying tumor tissue have been conjugated to cytotoxic agents and used to successfully eradicate tumors in a mouse model. With the ultimate goal of developing similar methods for treating human cancer, we describe an in vivo RPL screening process that, unlike previous in vivo experiments, does not harm the animal being screened. METHODS: RPLs were administered to FVB, BalbC, and tumor-bearing MRL/MpJ-fas(LPR) mice in a variety of dosing formats. Tumor nodules were excised 10 min following infusion and phage were amplified from the specimens. Phage were reinjected into the same animal within 48 h. This process was repeated twice for a total of three in vivo screens of mouse tumor tissue within the same animal. Mice were observed for systemic side effects, histopathologic damage, and presence of phage in organs. Peptide sequences were determined from several third-pan phage clones. RESULTS: Overall there was minimal toxicity from administration of single or repeat doses of RPLs. Amino acid consensus sequences were identified and some of the sequences were similar to those of peptide ligands that bind matrix metalloproteinases. CONCLUSIONS: Serial administration of an RPL is well tolerated and serial panning in individual mice leading to consensus sequence motifs is possible. Based on these preclinical data the Food and Drug Administration has approved the implementation of human clinical trials with this technique.

Amino Acid Sequence↗
PubMed2002

Flt3 ligand therapy for recipients of allogeneic bone marrow transplants expands host CD8 alpha(+) dendritic cells and reduces experimental acute graft-versus-host disease.

Recent evidence suggests that dendritic cells (DCs) can regulate and amplify immune responses. Flt3 ligand (FL)-derived DC function was tested as a stimulator of allogeneic lymphocytes in vitro and in vivo. Treatment of mice with FL dramatically expanded DC number, but DCs isolated from FL-treated mice (FL DCs) were poor stimulators of allogeneic T-cell responses in vitro. Further activation of FL DCs did not restore their stimulatory ability, and FL DCs did not suppress the stimulation of the allogeneic T cells by normal DCs. FL treatment significantly increased the CD8 alpha(+) DC subset, which appeared to be the reason for their poor stimulatory capacity. These observations were confirmed in vivo using a mouse model of acute graft-versus-host disease (GVHD) wherein host DCs play a critical role. FL treatment of recipients before allogeneic bone marrow transplantation dramatically suppressed donor T-cell responses to host antigens, thereby reducing GVHD mortality (P <.01). These data represent a novel strategy that alters host DCs and reduces acute GVHD.

Acute Disease↗
PubMed2002

Donor leukocyte infusion from immunized donors increases tumor vaccine efficacy after allogeneic bone marrow transplantation.

Donor T cells play a critical role in mediating both harmful graft-versus-host disease (GVHD) and beneficial graft-versus-tumor effect after allogeneic bone marrow transplantation (BMT). We have recently demonstrated a novel treatment strategy to stimulate specific antitumor activity with preservation of tolerance to host antigens after T cell-depleted allogeneic BMT by vaccination of recipients with irradiated B16 melanoma cells engineered to secrete granulocyte-macrophage colony-stimulating factor. In this murine system, donor leukocyte infusion from a donor immunized with the recipient-derived B16 vaccines enhanced clinical activity of tumor vaccines without exacerbating GVHD. CD4(+) T cells are essential for this enhancement. In vitro analysis of splenocytes from donor leukocyte infusion donor mice demonstrated that immunization of donors with the recipient-derived B16 vaccines elicited potent T-cell proliferation and cytokine responses specific to B16 antigens. These results demonstrate that immunization of donors with recipient-derived tumor vaccines preferentially induces tumor-specific T-cell responses and that vaccination of both donors and recipients can generate potent antitumor immunity without exacerbating GVHD. This strategy has important implications to prevent recurrence of malignancies after BMT.

Animals↗
PubMed2002

Identification of novel non-phosphorylated ligands, which bind selectively to the SH2 domain of Grb7.

Grb7 is an adapter-type signaling protein, which is recruited via its SH2 domain to a variety of receptor tyrosine kinases (RTKs), including ErbB2 and ErbB3. It is overexpressed in breast, esophageal, and gastric cancers, and may contribute to the invasive potential of cancer cells. Molecular interactions involving Grb7 therefore provide attractive targets for therapeutic intervention. We have utilized phage display random peptide libraries as a source of small peptide ligands to the SH2 domain of Grb7. Screening these libraries against purified Grb7 SH2 resulted in the identification of Grb7-binding peptide phage clones that contained a non-phosphorylated Tyr-X-Asn (YXN) motif. The tyrosine-phosphorylated form of this motif is characteristic of Grb7 SH2 domain binding sites identified in RTKs and other signaling proteins such as Shc. Peptides that are non-phosphorylated have greater potential in the development of therapeutics because of the instability of a phosphate group in vivo. Using a biased library approach with this conserved YXN motif, we identified seven different peptide phage clones, which bind specifically to the SH2 domain of Grb7. These peptides did not bind to the SH2 domain of Grb2 (which also selects for Asn at pY(+2)) or Grb14, a closely related family member. The cyclic structure of the peptides was required to bind to the Grb7 SH2 domain. Importantly, the synthetic Grb7-binding peptide G7-18 in cell lysates was able to specifically inhibit the association of Grb7 with the ErbB family of RTKs, in particular ErbB3, in a dose-dependent manner. These peptides will be useful in the development of targeted molecular therapeutics for cancers overexpressing Grb7 and in the development of Grb7-specific inhibitors to gain a complete understanding of the physiological role of Grb7.

Amino Acid Motifs↗
PubMed2002

Acute graft-versus-host disease does not require alloantigen expression on host epithelium.

Alloantigen expression on host antigen-presenting cells (APCs) is essential to initiate graft-versus-host disease (GvHD); therefore, alloantigen expression on host target epithelium is also thought to be essential for tissue damage. We tested this hypothesis in mouse models of GvHD using bone-marrow chimeras in which either major histocompatibility complex class I or class II alloantigen was expressed only on APCs. We found that acute GvHD does not require alloantigen expression on host target epithelium and that neutralization of tumor necrosis factor-alpha and interleukin-1 prevents acute GvHD. These results pertain particularly to CD4-mediated GvHD but also apply, at least in part, to CD8-mediated GvHD. These results challenge current paradigms about the antigen specificity of GvHD effector mechanisms and confirm the central roles of both host APCs and inflammatory cytokines in acute GvHD.

Acute Disease↗
PubMed2002

Combination of interferon alfa-2b and ribavirin in liver transplant recipients with histological recurrent hepatitis C.

Recurrent hepatitis C virus (HCV) infection is an important cause of fibrosis and cirrhosis after liver transplantation (LT), with histological recurrence developing in at least 50% of patients within the first year. The aim of this study is to assess the safety and efficacy of interferon alfa-2b plus ribavirin in treating histological recurrent HCV after LT. Since 1998, patients with HCV with significant histological recurrence (fibrosis >/= 3 and/or histological activity index >/= 5) or progressive cholestatic disease after LT were treated with interferon alfa-2b (3 million units subcutaneously three times weekly) plus ribavirin (800 to 1,000 mg/d) for 12 months. Immunosuppression was tapered to cyclosporine/FK506 monotherapy. HCV RNA was assessed at entry, week 24, end of treatment, and 6 months after therapy. The primary end point was loss of HCV RNA 6 months after therapy, whereas the secondary end point was histological response. Fifty-four patients met criteria for treatment and have completed follow-up. Patients were mainly men (71% men; mean age, 51 +/- 5 years) with genotype 1 infection (88%) and high viral load (mean HCV RNA, 38 +/- 9 mEq/mL). Dose modification was required in 72% of patients because of cytopenia or side effects. Intent-to-treat analysis showed that serum HCV RNA was undetectable in 19 patients (35%) week 24, 21 patients (38%) week 48, and 16 patients (30%) at the 6-month follow-up. Paired liver biopsy results (before and within 6 months after treatment) were available for 35 patients. Patients who achieved viral eradication had no significant progression of fibrosis after 1 year of therapy. In summary, combination therapy is a reasonable antiviral option for recurrent HCV infection for established post-LT hepatitis and appears to prevent histological progression of disease if viral eradication is successful.

Adult↗
PubMed2002

Enhanced allostimulatory activity of host antigen-presenting cells in old mice intensifies acute graft-versus-host disease.

Older bone marrow transplantation (BMT) recipients are at heightened risk for acute graft-versus-host disease (GVHD) after allogeneic BMT, but the causes of this association are poorly understood. Using well-characterized murine BMT models we have explored the mechanisms of increased GVHD in older mice. GVHD mortality, morbidity, and pathologic and biochemical indices were all worse in old recipients. Donor T cell responses were significantly increased in old recipients both in vivo and in vitro when stimulated by antigen-presenting cells (APCs) from old mice, which also secreted more TNF-alpha and IL-12 after LPS stimulation. In a B6 --> B6D2F1 model, CD4(+) donor T cells but not CD8(+) T cells mediated more severe GVHD in old mice. We confirmed the role of aged APCs in GVHD using B6D2F1 BM chimeras created with either old or young BM. Four months after chimera creation, allogeneic BMT from B6 donors caused significantly worse GVHD in old BM chimeras. APCs from these mice also stimulated greater responses from allogeneic cells in vitro. These data demonstrate a hitherto unsuspected mechanism of amplified donor T cell responses by aged allogeneic host APCs that increases acute GVHD in aged recipients in this BMT model.

Aging↗
PubMed2002

In vitro permeation of tetramethylpyrazine across porcine buccal mucosa.

AIM: To examine the in-vitro transport route of tetramethylpyrazine (TMP) across porcine buccal mucosa and to investigate the effects of drug concentration, pH in donor chamber, and 1-octanol/buffer partition coefficient on transbuccal permeation. METHODS: In-vitro permeation of TMP through porcine buccal mucosa was studied by using in-line flow through diffusion cells at 37 . The permeability of TMP was evaluated at different donor pH and drug concentration. Permeability of unionized (Pu) and ionized TMP (Pi) was calculated by using the Scientist software. RESULTS: The steady state flux of TMP increased linearly with the donor concentration (r2=0.96) at pH 7.4. The permeability and the partition coefficient increased with pH. Pu and Pi were 9.05 x 10(-6) cm.s(-1) and 2.99 x 10(-7) cm.s(-1), respectively. The total permeability coefficient increased with the fraction of unionized form. CONCLUSION: TMP permeated through buccal mucosa by a passive diffusion process. The partition coefficient and pH dependency of drug permeability indicated that the drug was transported mainly via the transcellular route by a partition mechanism.

Absorption↗
PubMed2002

[The expressions of TGF-beta1 and Smad 2 mRNA on diseased glomeruli and their significance in the development of glomerulosclerosis].

OBJECTIVE: To explore the expressions of transforming growth factor-beta1 (TGF-beta1) and its signaling transduction molecule Smad 2 and their significance in the development of glomerulosclerosis. METHODS: Using in situ hybridization and immunohistochemistry to detect Smad 2 mRNA expression and TGF-beta1, collagen IV, fibronectin expression in renal biopsies from 61 cases with a spectrum of glomerulonephritis including IgA nephropathy (40 cases), membranous glomerulonephritis (10 cases) and sclerosing glomerulonephritis (11 cases), compared with 11 cases of glomerular mild lesion with image analysis system. RESULTS: With the exception of Smad 2 mRNA expression in mild type IgA nephropathy, all other types of diseased glomeruli showed increased expression of both TGF-beta1 and Smad 2 mRNA when compared with the 11 cases of mild glomerular lesions. The expressions of glomerular TGF-beta1 and Smad 2 mRNA positively correlated with collagen IV and fibronectin deposition in the glomeruli. CONCLUSIONS: TGF-beta1 and Smad 2 may be involved in the excessive deposition of glomerular extracellular matrix and play an important role in the development of glomerulosclerosis.

Collagen Type IV↗
PubMedDate not supplied

Tumor cell targeting of transferrin-PEG-TNF-alpha conjugate via a receptor-mediated delivery system: design, synthesis, and biological evaluation.

PEGylation is a procedure of growing interest for enhancing the therapeutic and biotechnological potential of peptides and proteins. Transferrin (Tf) has been proposed to be useful for targeting cancer cells. The aim of this study was to modify PEGylated recombinant human tumor necrosis factor alpha (PEG-TNF-alpha) with Tf to form Tf-PEG-TNF-alpha conjugates, which would maintain the advantages of PEGylation and also achieve the function of active targeting to tumor cells. In PEGylation reactions with 5-, 20-, 40-, and 60-fold molar excess of 3.4 kDa N-hydroxysuccinimide-PEG-maleimide (PT1, PT2, PT3, and PT4, respectively), PEG-TNF-alpha conjugates with different PEG chains were synthesized. A perfusion chromatography technique using a cation-exchange column was introduced to purify PEG-TNF-alpha conjugates. PT4 with about five PEG chains was selected as a lead candidate due to highest extent of PEGylation and maximum reaction yield. Thiolated Tf was conjugated to the maleimide group at the distal end of the PEG chains on the PEG-TNF-alpha conjugates, with the resulting Tf-PEG-TNF-alpha conjugates after purification containing approximately one Tf ligand on one TNF-alpha molecule. The conjugate of Tf and PT4 (TPT4) was selected to assess the specificity and affinity to transferrin receptor (TfR) on two kinds of tumor cells, K562 and KB. Both the receptor binding assays and the competition experiments were performed using radioligand binding analysis. The results demonstrated that TPT4 as well as Tf bound specifically to the TfR on the tumor cell surface and the affinity of the conjugate to TfR was similar to that of native Tf. In contrast, PEG-TNF-alpha demonstrated no specificity. The biodistribution and antitumor effects were investigated in S-180 tumor-bearing mice. It was found that TPT4 could markedly alter in vivo behavioral characteristics of TNF-alpha. Compared with TNF-alpha and PT4, extravasated TPT4 in tumor tissues exhibited a significantly delayed blood clearance and the highest intratumoral TNF-alpha levels. Furthermore, the inhibitory rate of tumor of TPT4 enhanced 5.3- and 1.8-fold over that of TNF-alpha and PT4, indicating that TPT4 exhibited the highest antitumor activity. These results suggested that Tf-PEG-TNF-alpha was a useful long circulating conjugate with the capabilities of specific receptor binding resulting in enhanced antitumor activity of TNF-alpha.

Animals↗
PubMedDate not supplied

Breast implants as a possible etiology of epithelioid hemangioendothelioma and successful therapy with interferon-alpha2.

Epithelioid hemangioendothelioma is a rare vascular tumor with unpredictable behavior. It often presents as liver or lung nodules and is refractory to conventional chemotherapy. Surgical resection and/or liver transplantation have been the mainstay of therapy, but the results are mixed and unsatisfactory. Although the etiology of this malignancy is unknown, an increased incidence in women has been noted, and an association with exposure to vinyl chloride is emerging as a possible risk factor. This review proposes polyurethane/silicone breast implants as a potential cause of the condition and highlights the dramatic response to interferon (IFN)-alpha in a woman, so exposed, with widespread disease in the liver and lungs. The implications for other women who have had this type of implant could be significant, and the early use of IFN-alpha may be optimal.

Antineoplastic Agents↗