Search PubMed⌕ Search

Biomedical subjects

Feng Liu

Publications and source records attributed to Feng Liu.

At least 127 records · Page 7Linked to original sources
PubMed2005

Expression of IgSF in salivary adenoid cystic carcinoma and its relationship with invasion and metastasis.

BACKGROUND: The aim of the present work was to study the potential effect of intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1) and neural cell adhesion molecule (NCAM) of immunoglobulin superfamily on the invasion and metastasis of salivary adenoid cystic carcinoma (SACC). METHOD: The expressions of ICAM-1, VCAM-1 and NCAM of forty cases with SACC were examined by immunohistochemical methods using respective kits. RESULTS: A significant relation showed between the expression level and histological differentiation, expression of ICAM-1 and VCAM-1 in solid SACC was greatly increased compared with NCAM; SACC with metastatic lymph node or local recurrence displayed significant relationship to the up-regulation of ICAM-1 and VCAM-1, and to the down-regulation of NCAM. CONCLUSIONS: It is proposed that ICAM-1 and VCAM-1 may play a role in the invasion and metastasis of SACC. NCAM may be an invasion-resistant adhesion molecule.

Adult↗
PubMed2005

Gene transcription profile in mice vaccinated with ultraviolet-attenuated cercariae of Schistosoma japonicum reveals molecules contributing to elevated IFN-gamma levels.

Vaccination with ultraviolet-attenuated cercariae of Schistosoma japonicum induced protective immunity against challenge infection in experimental animal models. Our preliminary study on the transcription levels of IFN-gamma and IL-4 in splenic CD4+ T cells revealed that attenuated cercariae elicited predominantly a Th1 response in mice at the early stage, whereas normal cercariae stimulated primarily Th2-dependent responses. Further analysis on the gene profile of the skin-draining lymph nodes demonstrated that the levels of IFN-gamma were significantly higher in vaccinated mice than those in infected mice at day 4, 7 and 14 post-vaccination or post-infection. However, for IL-12 and IL-4, the potent inducers of Th1 and Th2 responses, respectively, as well as IL-10, there were no differences over the course of the experiment between the infected and vaccinated mice. To explore the underlying factors that may potentially contribute to elevated IFN-gamma in vaccinated mice, the mRNA profiles of the skin-draining lymph nodes at day 4 post-exposure were compared using oligonucleotide microarrays. Within the 847 probe sets with increased signal values, we focused on chemokines, cytokines and relevant receptors, which were validated by semi-quantitative RT-PCR. A comprehensive understanding of the immune mechanisms of attenuated cercariae-induced protection may contribute to developing efficient vaccination strategies against S. japonicum, especially during the early stage of infection.

Animals↗
PubMed2005

Identification of immunodominant Th1-type T cell epitopes from Schistosoma japonicum 28 kDa glutathione-S-transferase, a vaccine candidate.

Th1-type cytokines produced by the stimulation of Th1-type epitopes derived from defined schistosome-associated antigens are correlated with the development of resistance to the parasite infection. Schistosoma mansoni 28 kDa glutathione-S-transferase (Sm28GST), a major detoxification enzyme, has been recognized as a vaccine candidate and a phase II clinical trial has been carried out. Sheep immunized with recombinant Schistosoma japonicum 28GST (Sj28GST) have shown immune protection against the parasite infection. In the present study, six candidate peptides (P1, P2, P3, P4, P7 and P8) from Sj28GST were predicted, using software, to be T cell epitopes, and peptides P5 and P6 were designed by extending five amino acids at the N-terminal and C-terminal of P1, respectively. The peptide 190-211 aa in Sj28GST corresponding to the Th1-type epitope (190-211 aa) identified from Sm28GST was selected and named P9. The nine candidate peptides were synthesized or produced as the fusion protein with thioredoxin in the pET32c(+)/BL21(DE3) system. Their capacity to induce a Th1-type response in vitro was measured using lymphocyte proliferation, cytokine detection experiments and flow cytometry. The results showed that P6 (73-86 aa) generated the strongest stimulation effect on T cells among the nine candidate peptides, and drove the highest level of IFN-gamma and IL-2. Therefore, P6 is a functional Th1-type T cell epitope that is different from that in Sm28GST, and will be useful for the development of effective vaccines which can trigger acquired immunity against S. japonicum. Moreover, our strategy of identifying the Th1-type epitope by a combination of software prediction and experimental confirmation provides a convenient and cost-saving alternative approach to previous methods.

Amino Acid Sequence↗
PubMed2005

Inactivation of CtIP leads to early embryonic lethality mediated by G1 restraint and to tumorigenesis by haploid insufficiency.

CtIP interacts with a group of tumor suppressor proteins including RB (retinoblastoma protein), BRCA1, Ikaros, and CtBP, which regulate cell cycle progression through transcriptional repression as well as chromatin remodeling. However, how CtIP exerts its biological function in cell cycle progression remains elusive. To address this issue, we generated an inactivated Ctip allele in mice by inserting a neo gene into exon 5. The corresponding Ctip(-/-) embryos died at embryonic day 4.0 (E4.0), and the blastocysts failed to enter S phase but accumulated in G(1), leading to a slightly elevated cell death. Mouse NIH 3T3 cells depleted of Ctip were arrested at G(1) with the concomitant increase in hypophosphorylated Rb and Cdk inhibitors, p21. However, depletion of Ctip failed to arrest Rb(-/-) mouse embryonic fibroblasts (MEF) or human osteosarcoma Saos-2 cells at G(1), suggesting that this arrest is RB dependent. Importantly, the life span of Ctip(+/-) heterozygotes was shortened by the development of multiple types of tumors, predominantly, large lymphomas. The wild-type Ctip allele and protein remained detectable in these tumors, suggesting that haploid insufficiency of Ctip leads to tumorigenesis. Taken together, this finding uncovers a novel G(1)/S regulation in that CtIP counteracts Rb-mediated G(1) restraint. Deregulation of this function leads to a defect in early embryogenesis and contributes, in part, to tumor formation.

Animals↗
PubMed2005

PDK2: the missing piece in the receptor tyrosine kinase signaling pathway puzzle.

Activation of members of the protein kinase AGC (cAMP dependent, cGMP dependent, and protein kinase C) family is regulated primarily by phosphorylation at two sites: a conserved threonine residue in the activation loop and a serine/threonine residue in a hydrophobic motif (HM) near the COOH terminus. Although phosphorylation of these kinases in the activation loop has been found to be mediated by phosphoinositide-dependent protein kinase-1 (PDK1), the kinase(s) that catalyzes AGC kinase phosphorylation in the HM remains uncharacterized. So far, at least 10 kinases have been suggested to function as an HM kinase or the so-called "PDK2," including mitogen-activated protein (MAP) kinase-activated protein kinase-2 (MK2), integrin-linked kinase (ILK), p38 MAP kinase, protein kinase Calpha (PKCalpha), PKCbeta, the NIMA-related kinase-6 (NEK6), the mammalian target of rapamycin (mTOR), the double-stranded DNA-dependent protein kinase (DNK-PK), and the ataxia telangiectasia mutated (ATM) gene product. However, whether any or all of these kinases act as a physiological HM kinase remains to be established. Nonetheless, available data suggest that multiple systems may be used in cells to regulate the activation of the AGC family kinases. It is possible that, unlike activation loop phosphorylation, phosphorylation of the HM site in the different AGC family kinases is mediated by distinct kinases. In addition, phosphorylation of the AGC family kinase at the HM site could be cell type, signaling pathway, and substrate specific. Identification and characterization of the bonafide HM kinase(s) will be essential to verify these hypotheses.

3-Phosphoinositide-Dependent Protein Kinases↗
PubMed2005

The effects of stellate ganglion block on visual evoked potential and blood flow of the ophthalmic and internal carotid arteries in patients with ischemic optic neuropathy.

Ischemic optic neuropathy (ION) is a common disease that can cause a loss of visual acuity in the elderly. We treated ION patients with stellate ganglion block (SGB) and investigated its effects on picture visual evoked potential (P-VEP) and blood flow in the ophthalmic artery (OA) and internal carotid artery (ICA). Twelve ischemic eyes in 12 patients diagnosed by the same ophthalmologist were investigated in this study. All patients were treated with daily SGB on the affected side with 2-3 mL of 2% lidocaine for a treatment period of 10-15 days. In ION eyes before SGB, compared with healthy eyes, the latency of P-VEP P(100) was delayed (123 +/- 14 ms versus 98 +/- 3 ms; P < 0.05), and the amplitude was reduced (4.24 +/- 1.76 microV versus 10.26 +/- 4.09 microV; P < 0.05). After SGB, the latency and amplitude returned to normal (103 +/- 6 ms versus 98 +/- 3 ms; 10.43 +/- 4.88 microV versus 10.26 +/- 4.09 microV; P > 0.05). Before treatment, the blood flow velocities of the OA and the ICA on the ischemic side were slow and the resistance indexes were high, but SGB reduced these changes. SGB did not affect the OA and the ICA on the healthy side. We conclude that SGB improves P-VEP and OA and ICA blood flow in ION eyes. Further studies are needed to confirm that this is an effective method for the treatment of ION.

Adult↗
PubMed2005

[Clinicopathologic significance of CD105 mRNA expression in human breast carcinoma].

OBJECTIVE: To study endoglin (CD105) gene expression in breast cancer and its clinicopathologic significance. METHODS: In 40 patients with breast cancers, CD105 mRNA was detected at center and periphery of tumor and at nearby normal tissue by RT-PCR. RESULTS: The difference in CD105 mRNA expressions between cancer and normal breast tissue was significant (t = 12.08, P < 0.05), and the expression was significantly higher at the tumor periphery than at the tumor center (t = 7.52, P < 0.05). CD105 over-expression was related to lymph node metastases (t = 2.71, P < 0.05), but not to age, tumor size, pathologic grade or pathologic type (P > 0.05). CONCLUSION: CD105 over-expression may play a crucial role in the progression of breast cancer and lymph node metastasis.

Adult↗
PubMed2005

[Inducement effect of (DIPP-L-Trp)2-L-Lys-OCH3 on apoptosis of K562 cells through mitochondrial-dependent pathway].

BACKGROUND & OBJECTIVE: Phosphorylation of protein and peptide plays an important role in life activity. Some phosphoryl peptides are found to have activities to inhibit proliferation of tumor cells, but the involved mechanisms are unclear. This study was designed to investigate cell apoptosis induced by (O,O-diisopropyl phosphoryl-L-tryptophan)(2)-L-lysine methyl ester [(DIPP-L-Trp)(2)-L-Lys-OCH(3)], and its mechanism in K562 cells. METHODS: K562 cells were double stained by AnnexinV-FITC and propidium iodide (PI) to detect (DIPP-L-Trp)(2)-L-Lys-OCH(3)-induced apoptosis by flow cytometry (FCM). After treatment of different concentrations of (DIPP-L-Trp)(2)-L-Lys-OCH(3), K562 cells were stained by rhodamine123 and PI to detect changes in membrane potential (Delta Psi m), or stained by 2',7'-dichlorofluorescein diacetate (DCFH-DA) to detect reactive oxygen species (ROS) of mitochondrial by FCM. RESULTS: When treated with 50 microg/ml of (DIPP-L-Trp)(2)-L-Lys-OCH(3) for 24 h, apoptosis rate of K562 cells was 61.9%, Delta Psi m was decreased in 93.6% of K562 cells,and ROS production was decreased. Both Delta Psi m and ROS production in K562 cells mitochondria were decreased with the increasing concentration and extending treatment time of (DIPP-L-Trp)(2)-L-Lys-OCH(3). CONCLUSION: (DIPP-L-Trp) (2)-L-Lys-OCH(2) could induce apoptosis in K562 cells, which might relate with down-regulation of mitochondrial Delta Psi m and reduction of ROS production.

Apoptosis↗
PubMed2005

[Modified low-potassium dextran solution in heart-lung transplantation].

OBJECTIVE: To determine the application of modified low-potassium dextran (LPD) solution in heart-lung transplantation. METHODS: We used the modified LPD as the lung flush solution of the donor in the first heart-lung transplantation procedure in Hunan. RESULTS: The patient survived 555 days after the surgery and severe infection, lung disfunction or severe graft rejection never occurred. CONCLUSION: Modified LPD as lung flush solution of the donor during heart-lung transplantation demonstrates an excellent effect of lung protection.

Adult↗
PubMed2005

[Mucosal pathologic and ultrastructure changes of experimental maxillary sinusitis in rabbits].

OBJECTIVE: To investigate mucosal pathologic and ultrastructure changes relate to experimental maxillary sinusitis process in rabbits. The demarcation of acute and chronic maxillary sinusitis will be determined according to pathologic effects. METHOD: Thirty New Zealand white rabbits have been induced sinusitis will be divided into different groups according to the time of process. The pathologic changes are observed by microscope, scanning electric microscope and transmission electric microscope. RESULT: Within 3 weeks to induce infection the inflammation mainly show in acute style while after 3 weeks the main manifestation are chronic changes. In epithelium layer cilia shedding increased, the number of goblet cell added, squamous epithelium metaplasia and epithelia necrosis were observed during inflammatory process. In lamina propria glands metaplasia and decreased, the fibrosis is densed. CONCLUSION: The pathologic changes of maxillary mucosa are related to process. The borderline of acute and chronic experimental maxillary sinusitis is 3 weeks.

Animals↗
PubMed2005

[Measurement of macular edema in retinal vein occlusion using optical coherence tomography and its visual prognosis].

OBJECTIVE: To examine the type of macular edema in patients with retinal vein occlusion by using optical coherence tomography (OCT). To compare the sensitivity and specificity between OCT and fundus fluorescein angiography (FFA). To investigate the visual prognosis and risk factors in patients with cystoid macular edema (CME). METHODS: Ninety-one eyes of 90 patients with various types of retinal vein occlusion were examined by OCT and FFA. There were 54 cases male and 36 cases female. The age of these patients ranged from 20 to 74 years old and averaged (57.8 +/- 13.8) years old. Right eye was affected in 45 cases, and left eye in 46 cases (both eye in 1 case). Central retinal vein, hemicentral retinal vein and branch retinal vein were affected in 54, 9 and 28 eyes, respectively. The average follow-up period was 6.10 months. The sensitivity and specificity of OCT and FFA were measured. The visual prognosis and risk factors were analyzed. Macular central retinal thickness of 54 opposite normal eye was measured for comparison. RESULTS: (1) The classification of macular edema by OCT was cystoid macular edema in 71 eyes (78.0%); subretinal fluid in 14 eyes and laminar macular hole in 1 eye. The minimal and maximal height of intraretinal cystoid space was 94 microm and 1317 microm, respectively and averaged (668.18 +/- 245.58) microm. The minimal and maximal height of macular central retinal thickness of 54 opposite normal eye was 110 microm and 236 microm, respectively and averaged (154.09 +/- 21.85) microm. The maximal height of subretinal fluid space was 1377 microm or even beyond the detective limit of OCT. (2) The sensitivity of OCT for detection of CME was 98.6% and the specificity was 100%. The sensitivity of FFA was 86.1% and the specificity was 100.0%. (3) The visual prognosis of 61 eyes with CME follow-up over 3 months: The difference between the initial and final VA in branch retinal vein occlusion was statistically significant (P < 0.01), while no difference between initial and final VA in central and hemicentral retinal vein occlusion (P > 0.05). The factors affected visual prognosis of CME included the duration, the presence of hemorrhage in cystoid space and the severity of occlusion, etc. In CME under 3 months, the visual prognosis after therapy is better than that of before the therapy (P < 0.01); while in eyes with duration more than 3 months, no difference of vision could be detected before and after the therapy (P > 0.05). CONCLUSIONS: OCT is a safe, high-resolution, non-invasive, reliable and reproducible new examine method for detecting CME. The visual prognosis of CME is poor. It is possible that the visual prognosis can be improved by early detecting CME using OCT.

Adult↗
PubMed2005

[A study on stem cell mobilization after partial liver transplantation in rats].

OBJECTIVE: To explore the role of stem cell mobilization on regeneration of partially grafted livers. METHODS: Rats models with cross-sex 50% PLTx (partial liver transplantation) were established. The rats were divided into three groups: PLTx, WLTx (whole liver transplantation) and sham operation groups. Bone marrow and liver samples were collected on days 1, 3, 5, 7 postoperatively (each n = 6). The quantitative variations of the cells with stem cell markers in the bone marrow, including beta2m-/Thy-1.1+, CD45+/CD34+, Flt2/3+ and c-kit+ markers, were detected using flow cytometry. Sry gene positive cells in donor livers were detected by fluorescent in situ hybridization (FISH), and the expressions of CD34, c-kit and Thy-1.1 were detected by immunohistochemistry technique. RESULTS: Compared with the WLTx and sham operation groups, beta2m-/Thy-1.1+, CD45+/CD34+ cells in bone marrows in the PLTx group increased on the first postoperative day and decreased on the following days. The CD34, c-kit and Thy-1.1 positive cells detected in portal tract areas peaked during the 3-5 postoperative days. CD34+/CD45+ positive cells could be detected. The expressions of CD34, c-kit and Thy-1.1 positive cells were rare in the WLTx and sham operation groups. Sry+ cells could be detected in portal tract areas and few Sry+/CD34+ and Sry+/Thy-1.1+cells were detected. CONCLUSION: In the PLTx group, the stem cells in the bone marrow were mobilized and stem cells in the liver were activated.

Animals↗
PubMed2005

[Analysis of recombinant erythropoietin and its tryptic digest by capillary electrophoresis and capillary electrophoresis-electrospray ionization-mass spectrometry using capillary coated with 6,6-ionene].

The microheterogeneity of recombinant human erythropoietin (rhEPO) was analyzed by capillary electrophoresis (CE) using a capillary coated with 6,6-ionene. The applicability of a volatile electrolyte for fast analysis of tryptic fragments of rhEPO with online CE-electrospray ionization-mass spectrometry (ESI-MS) was investigated, resulting in a reproducible separation of eleven rhEPO tryptic fragments within 22 min under the following conditions: running buffer 300 mmol/L acetic acid-ammonium acetate (HAc-NH4Ac), pH 4.80, separation voltage -15 kV and capillary temperature 25 degrees C. The proposed method is rapid and effective, and can be used for the structural analysis of related proteins.

Electrophoresis, Capillary↗
PubMed2004

Numerical modelling of thermal effects in rats due to high-field magnetic resonance imaging (0.5-1 GHZ).

A finite-difference time-domain (FDTD) thermal model has been developed to compute the temperature elevation in the Sprague Dawley rat due to electromagnetic energy deposition in high-field magnetic resonance imaging (MRI). The field strengths examined ranged from 11.75-23.5 T (corresponding to 1H resonances of 0.5-1 GHz) and an N-stub birdcage resonator was used to both transmit radio-frequency energy and receive the MRI signals. With an in-plane resolution of 1.95 mm, the inhomogeneous rat phantom forms a segmented model of 12 different tissue types, each having its electrical and thermal parameters assigned. The steady-state temperature distribution was calculated using a Pennes 'bioheat' approach. The numerical algorithm used to calculate the induced temperature distribution has been successfully validated against analytical solutions in the form of simplified spherical models with electrical and thermal properties of rat muscle. As well as assisting with the design of MRI experiments and apparatus, the numerical procedures developed in this study could help in future research and design of tumour-treating hyperthermia applicators to be used on rats in vivo.

Animals↗
PubMed2004

Roles of PDK-1 and PKN in regulating cell migration and cortical actin formation of PTEN-knockout cells.

Mutations in the tumor suppressor protein PTEN (phosphatase and tensin homologue deleted on chromosome 10) enhance cell migration, yet the underlying molecular mechanisms remain largely uncharacterized. Loss of PTEN in mouse embryonic fibroblasts (MEFs) correlates with striking cortical actin accumulation. However, how loss of PTEN leads to cortical actin formation and whether the presence of cortical actin contributes to the increased cell migration are unclear. Here we show that overexpression of dominant-negative forms of (DN) PTEN, RhoA or its kinase-dead (KD) effector, PKN, inhibited cortical actin formation, indicating that cortical actin of Pten(-/-) MEFs is mediated by the PTEN/Rho/PKN pathway. However, neither DN RhoA nor KD PKN inhibited the enhanced migration of Pten(-/-) cells, in contrast to the inhibitory effect of DN Rac. In agreement with the previous observation that DN Akt inhibits migration of Pten(-/-) cells, we demonstrate here that overexpression of KD PDK-1, the Akt kinase, reduces Pten(-/-) cell migration. Furthermore, overexpression of DN forms of Akt, Rac, or PDK-1, all of which inhibit migration of Pten(-/-) cells, had no effect on cortical actin accumulation. Our findings suggest that PDK-1/Akt signaling pathway plays a major role in regulating cell migration induced by PTEN deficiency.

3-Phosphoinositide-Dependent Protein Kinases↗