Biomedical subjects

Yi Shen

Publications and source records attributed to Yi Shen.

At least 37 records · Page 2Linked to original sources

PubMed2005

A rice glutamate receptor-like gene is critical for the division and survival of individual cells in the root apical meristem.

Glu receptors are known to function as Glu-activated ion channels that mediate mostly excitatory neurotransmission in animals. Glu receptor-like genes have also been reported in higher plants, although their function is largely unknown. We have identified a rice (Oryza sativa) Glu receptor-like gene, designated GLR3.1, in which mutation by T-DNA insertion caused a short-root mutant phenotype. Histology and DNA synthesis analyses revealed that the mutant root meristematic activity is distorted and is accompanied by enhanced programmed cell death. Our results supply genetic evidence that a plant Glu receptor-like gene, rice GLR3.1, is essential for the maintenance of cell division and individual cell survival in the root apical meristem at the early seedling stage.

Amino Acid Sequence↗

PubMed2005

Age-associated decline in mitochondrial respiration and electron transport in Drosophila melanogaster.

The principal objective of the present study was to identify specific alterations in mitochondrial respiratory functions during the aging process. Respiration rates and the activities of electron transport chain complexes were measured at various ages in mitochondria isolated from thoraces of the fruit fly, Drosophila melanogaster, which consist primarily of flight muscles. The rates of state 3 respiration (ADP-stimulated), RCRs (respiratory control ratios) and uncoupled respiration rates decreased significantly as a function of age, using either NAD+- or FAD-linked substrates; however, there were no differences in state 4 respiration (ADP-depleted) rates. There was also a significant age-related decline in the activity of cytochrome c oxidase (complex IV), but not of the other mitochondrial oxidoreductases examined. Exposure of mitochondria isolated from young flies to low doses of KCN or NaAz (sodium azide), complex IV inhibitors, decreased cytochrome c oxidase activity and increased the production of H2O2. Collectively, these results support the hypothesis that impairment of mitochondrial respiration may be a causal factor in the aging process, and that such impairment may result from and contribute to increased H2O2 production in vivo.

Aging↗

PubMed2005

Liquid-crystalline phase development of a mesogen-jacketed polymer-application of two-dimensional infrared correlation analysis.

Two-dimensional correlation spectroscopy has been applied to study PMPCS (poly{2,5-bis[(4-methoxyphenyl)oxycarbonyl]styrene}), a representative example of mesogen-jacketed liquid crystalline polymers. With the precise analysis of a series of Fourier transform infrared (FTIR) spectra of PMPCS recorded at varied temperatures, a reasonable mechanism of the development of liquid crystalline (LC) phase is proposed. Before the phase transition, the conformational change of individual side chains occurs sooner than that of the backbone due to the larger motional freedom of the side chains. After the phase transition, however, the readjustment of still somewhat mobile backbone occurs before the ordered, rigid, and mutually interacting side chains. That is, phase transition leading to the LC phase formation brings in a new cooperative restriction of motions to the segments.

Journal Article↗

PubMed2005

Heart fatty acid binding protein in the rapid evaluation of myocardial damage following valve replacement surgery.

BACKGROUND: Myocardial damage occurs following valve replacement surgery. We estimated the value of heart fatty acid binding protein (H-FABP) in these patients. METHODS: Sixty elected patients were enrolled and distributed into single (group A) and double (group B) valve replacement groups. The clinical data were outlined and blood samples were collected perioperatively for determination of plasma levels of H-FABP, cardiac troponin-I (cTn-I), and CK-MB in both groups. RESULTS: 56 patients completed the study and no significant difference of clinical data was observed except CPB time and ACC time between groups. H-FABP level elevated quickly after reperfusion and peaked significantly earlier than cTn-I and CK-MB, it also declined rapidly but did not return to baseline at 24 h after reperfusion. Three markers' levels were all higher in group B than in group A after reperfusion with significant differences at their peaks and thereafter. Patients with postoperative complications had significantly higher H-FABP levels than usual. H-FABP peak level associated well with the length of CPB and ACC as well as with other 2 markers' peak levels in both groups. CONCLUSION: Compared with cTn-I and CK-MB, H-FABP is an earlier and potentially useful marker in the rapid evaluation of myocardial damage following valve replacement surgery with CPB.

Adult↗

PubMed2005

[Gastrointestinal stromal tumor: a clinicopathological study of 74 cases].

OBJECTIVE: To explore a simplified and reproducible approach for the diagnosis and morphologic prognostication of gastrointestinal stromal tumor (GIST). METHODS: Eighty-five cases of gastrointestinal mesenchymal tumors including 74 cases of GIST, 8 esophageal smooth muscle tumor, 1 rectal leiomyosarcoma, 1 Schwannoma, and 1 malignant fibrous histiocytoma were studied by histological evaluation along with an immunohistochemistry panel including vimentin, CD117 (c-kit), CD34, SMA, desmin and S-100. Clinicopathological correlation was performed in 31 cases of GIST that had accompanied with the available follow-up data. RESULTS: Among 74 GISTs, 34 arose principally from the stomach, 30 from the small intestine, and 10 other cases found in the esophagus, retroperitoneum, mesenterium and omentum. The patients' age ranged from 23 to 80 years (mean 52.5 years), with 45 males and 29 females. Histologically, the tumors composed of either spindle or oval to round cells arranged in interlacing fascicles forming whorls or cellular clusters, cytoplasm generally abundant and eosinophilic. There were 48 cases of spindle cell type, 10 cases of epithelioid cell type and 16 cases of mixed cell type. All 74 cases of GIST were positive for CD117 in a cell membranous pattern, however, some variable staining patterns of CD117 had been noticed in a few cases. In addition, 54 GISTs were also positive for CD34 (72.9%), 25 cases positive for SMA, 5 cases positive for S-100 and 5 cases positive for desmin. According to the Fletcher's scheme, GISTs in this study were divided into 4 subcategories including groups of very low risk of aggressive behavior (3 cases), of low risk (15 cases), of intermediate risk (36 cases) and of high risk (20 cases) respectively. Kaplan-Meier survival analysis of 31 GIST cases whom had been followed up for 16 to 72 months showed a statistically significant difference present among the subcategories (P < 0.01). CONCLUSIONS: GISTs predominantly occur in the middle and old age patients, more common in male, and positive CD117 staining is considered to be the defining marker to differentiate GIST from other mesenchymal tumors of the GI tract. Positive CD34 immun-staining, plus a CD117 positivity, strengthens further a diagnosis of GIST. Subclassification of GISTs using Fletcher's scheme appears to be simple, reproducible, and correlates well with the clinical behavior of the tumor.

Actins↗

PubMed2005

[The effect of entrapment of CpG sequence with cationic PLG nanoparticles on the immune responses of mice to pig paratyphoid vaccine].

Cationic PLG nanoparticles and liposome were prepared and used as package molecules to pack up pUC18-CpG. The effects of the packed pUC18-CpG on the cellular and humoral immune responses were detected in the mice that were inoculated with pig paratyphoid vaccine. The results showed that compared with the control, the amount of IgG and the titre of specific antibody were significantly increased in the sera of mice immunized with the CpG plasmid entrapped by cationic PLG nanoparticles; the proliferation and induced IL-2 bioactivity of lymphocytes were significantly enhanced in the spleen of the immunized mice; the stimulatory effect of cationic PLG nanoparticles was similar to or stronger than that of cationic liposome. These indicated that cationic PLG nanoparticle could be employed as an effective package molecule to promote the immunostimulatory effect of pUC18-CpG.

Adjuvants, Immunologic↗

PubMed2005

[Research evolution of ultrasound beamforming technology].

In this paper, four typical beamformers are explained according to the development process of ultrasound imaging systems. Comparison and analysis are made from several aspects, such as performance, integration, cost, and so on. Furthermore, characteristics of an analog and three digital beamformers are respectively summarized. At last, the development direction of beamformers is pointed out.

Ultrasonics↗

PubMed2004

Electroorganic synthesis using a fluoride ion mediator under ultrasonic irradiation: synthesis of oxindole and 3-oxotetrahydroisoquinoline derivatives.

[reaction: see text] Anodic intramolecular cyclization of alpha-(phenylthio)acetamides using a fluoride ion mediator was realized. Under ultrasonic irradiation, cyclization was accelerated markedly to give desired cyclized products in moderate to good yields. The local heating effect of ultrasonic irradiation seems to be more advantageous than usual heating.

Journal Article↗

PubMed2004

Regulating effects of porcine interleukin-6 gene and CpG motifs on immune responses to porcine trivalent vaccines in mice.

In order to develop novel immunoadjuvants to boost immune response of conventional vaccines, experiments were conducted to investigate the regulating effects of porcine interleukin-6 gene and CpG motifs as the molecular adjuvants on immune responses of mice that were co-inoculated with trivalent vaccines against Swine fever, the Pasteurellosis and Erysipelas suis. Synthetic oligodeoxynuleotides containing CpG motifs were ligated into pUC18, forming recombinant pUC18-CpG plasmid. Eukaryotic plasmid expressing porcine interleukin-6 (VPIL-6) were also constructed as molecular adjuvants in an attempt to enhance levels of immune responses of mice co-administered with the trivalent vaccines in this paper. The cellular and humoral immune responses of mice were systematically analysed, and the experimental results were observed that the number of white blood cells, monocytes, granuloytes and lymphocytes significantly increased, respectively, in the mice immunized with VPIL-6, compared with those of the control; the IgG content and titre of specific antibodies to the trivalent vaccine mounted remarkably in the sera from the VPIL-6 vaccinated mice; the proliferation of lymphocytes and induced IL-2 activities were significantly increased in the vaccinated groups. The above-mentioned immune responses of mice co-inoculated with pUC18-CpG plasmid were significantly stronger than those of co-inoculated with pUC18 plasmid, suggesting that the immunostimulatory effect of oligodeoxynuleotides CpG is closely connected with the number of CpG motifs. These results suggest that the porcine IL-6 gene and CpG motifs could be employed as effective immunoadjuvants to elevate immunity to conventional vaccines.

Adjuvants, Immunologic↗

PubMed2004

The immunoregulation of mice by somatic transgenic expression of porcine interleukin-6 gene and CpG sequence.

Porcine IL-6 gene and CpG sequences were used to enhance some indirect indicators of the immune response of mice. An indirect ELISA was used to quantify the amount of IgG in the sera from mice that had been inoculated with VPIL-6, a recombinant VR1020 vector into which had been inserted the porcine IL-6 gene cloned in our laboratory, or with CpG, pUC18 or VR1020. The induced bioactivity of IL-2 of lymphocytes in the spleen was assayed by the MTT method, and the proliferation of lymphocytes stimulated with ConA was tested to identify the immune response of the experimental mice. The amount of IgG in the immunized mice was significantly higher than that in the control group. Among the immunized groups, inoculation with VPIL-6 induced the highest content of IgG (p < 0.05), the greatest bioactivity of IL-2 and the greatest proliferation of lymphocytes from the spleen of the mice. These results suggest that inoculation with porcine IL-6 gene and CpG sequences may enhance the immune response of mice, and might be used as an immunoadjuvant.

Adjuvants, Immunologic↗

PubMed2004

Pre-eclampsia is associated with the failure of melanoma cell adhesion molecule (MCAM/CD146) expression by intermediate trophoblast.

The purpose of this study was to determine whether the expression of melanoma cell adhesion molecule (MCAM/CD146), like most other endothelial adhesion molecules, is reduced in the pregnancy disorder pre-eclampsia, and whether it is associated with the invasiveness of trophoblast. We used immunohistochemical approaches and analyzed 42 placentas from control and pre-eclamptic patients using an anti-CD146 monoclonal antibody. Our data show that in normal placentas, CD146 staining was specifically detected in intermediate trophoblasts that are most invasive and migratory, but not detected in noninvasive cytotrophoblasts or syncytiotrophoblasts. However in pre-eclampsia, CD146 was no longer present in the intermediate trophoblasts, although it was detectable in the blood vessels. At the same time, we tested CD31/PECAM-1, another endothelial adhesion molecule, and found its negative staining for all kinds of trophoblasts in both normal and pre-eclamptic placentas. The different staining patterns of CD146 in the normal and pre-eclamptic placentas provide the first evidence that in pre-eclampsia, intermediate trophoblasts fail to express CD146, implicating that CD146 plays an important role in trophoblast invasion.

Adult↗

PubMed2004

[Postoperative Th1 and Th2 type cytokine changes in patients with esophageal squamous cell carcinoma and their clinical significance].

OBJECTIVE: To study the expressions of Th1 and Th2 type cytokines in patients with esophageal squamous cell carcinoma and the influence of operation on such expressions. METHOD: Enzyme-linked immunosorbent assay (ELISA) was used to detect Th1 (IL-2 and INF-gamma) and Th2 type cytokines (IL-4, IL-6 and IL-10) in cultured peripheral blood mononuclear cells (PBMCs, for 48 h) from 30 healthy controls and 46 esophageal squamous cell carcinoma patients (collected before and 8 and 30 d after operation, respectively). RESULTS: Compared with the control group, the expressions of Th1 type cytokines, IL-2 and INF-gamma, were significantly depressed in the PBMCs of the cancer patients (P<0.05), while expression of Th2 type cytokines, IL-6 was significantly enhanced (P<0.05), and IL-4 and IL-10 showed only slight enhancement. Such changes in the expressions of the cytokines showed a correlation with TNM (tumor-node-metastasis)stage of the tumors. After operation, the expressions of Th1 type cytokines increased and Th2 type cytokines decreased. CONCLUSIONS: Th1 cells are suppressed in patients with esophageal squamous cell carcinoma, while the function of Th2 cells is enhanced. Operation may reverse such changes, and dynamic detection of Th1 and Th2 type cytokines may indicate the prognosis, therapeutic effect and risks of relapse and metastasis.

Adult↗

PubMed2003

Estrogen affects BDNF expression following chronic constriction nerve injury.

To investigate the effect of estrogen on BDNF expression in neuropathic pain. Using chronic constriction injury model, we detected BDNF mRNA and protein level by reverse transcription polymerase chain reaction and enzyme-linked immunosorbent assay, respectively. A hot-plate test was used as a sign of neuropathic pain. The rats with higher estrogen level exhibited more sensitive to thermal stimuli and had a higher level of BDNF mRNA and protein expression. The results suggest that BDNF level can be elevated by estrogen and estrogen may potentiate the sensitivity to thermal stimuli by its effect on BDNF expression. Thus, this study improves our understanding of the role of estrogen in the nociceptive processing.

Animals↗

PubMed2003

A novel anti-CD146 monoclonal antibody, AA98, inhibits angiogenesis and tumor growth.

The goal of our study was to raise monoclonal antibodies (mAbs) against endothelial cell-surface proteins specific for tumor vasculature. Here, we describe the generation and intensive characterization of mAb AA98, including its functional properties and its antigen identification. In our study, an enhanced mAb AA98 immunoreactivity was observed on stimulated human umbilical vein endothelial cells (HUVECs). In addition, mAb AA98 showed remarkably restricted immunoreactivity against intratumoral neovasculature compared with blood vessels of normal tissues. We identified the AA98 antigen as human CD146, an adhesion molecule belonging to the immunoglobulin superfamily. Data from in vitro experiments imply structural and signaling functions for endothelial CD146; however, the role of CD146 in vivo is largely unknown. Here, we show that mAb AA98 displays antiangiogenic properties in vitro and in vivo. Proliferation and migration of HUVECs were inhibited by mAb AA98 as was angiogenesis in chicken chorioallantoic membrane (CAM) assays and tumor growth in 3 xenografted human tumor models in mice. Our data provide new insights into the function of CD146 on endothelial cells, validate CD146 as a novel target for antiangiogenic agents, and demonstrate that mAb AA98 has potential as a diagnostic and therapeutic agent in vascular and cancer biology.

Animals↗

PubMed2003

4-1BB (CD137) differentially regulates murine in vivo protein- and polysaccharide-specific immunoglobulin isotype responses to Streptococcus pneumoniae.

4-1BB (CD137) is induced on activated CD4(+) and CD8(+) T cells and delivers a costimulatory signal upon binding the 4-1BB ligand (4-1BBL) expressed on antigen-presenting cells. Induction of 4-1BB is dependent on activation via the T-cell receptor (TCR) and possibly CD28. It was previously demonstrated that both an in vivo protein (pneumococcal surface protein A [PspA])- and polysaccharide (phosphorylcholine [PC] determinant of teichoic acid)-specific immunoglobulin (Ig) isotype response to Streptococcus pneumoniae was dependent on CD4(+) TCRalphabeta(+) T cells and B7-dependent costimulation through CD28. We thus postulated that 4-1BB costimulation would also play a role in regulating the in vivo anti-PspA and anti-PC response to S. pneumoniae. We demonstrate that mice genetically deficient in 4-1BBL elicit a markedly reduced IgM and IgG anti-PC but normal primary and secondary IgG anti-PspA responses to S. pneumoniae relative to those for wild-type mice. However, injection of an agonistic anti-4-1BB monoclonal antibody (MAb), while having no significant effect on the anti-PC response, strongly inhibits the primary anti-PspA response, the generation of PspA-specific memory, and germinal center formation but does not induce a lasting state of tolerance. In contrast, anti-4-1BB MAb has no effect on the anti-PspA response when injected only at the time of secondary immunization. Delay of the addition of anti-4-1BB leads to progressively less inhibition of the primary response up to day 8. This inhibition is independent of CD8(+) T cells and is associated with the expansion of CD4(+) T cells with an activated phenotype, which is partly dependent on B7-dependent costimulation. These data are the first to suggest a stimulatory role for endogenous 4-1BB-4-1BBL interactions during a humoral immune response to a pathogen and further underscore significant differences in costimulation requirements for an in vivo protein- versus polysaccharide-specific Ig isotype response to an extracellular bacterium.

4-1BB Ligand↗

PubMed2003

[FDG dual-head tomography with coincidence imaging and serum tumor marker assays for the assessment of malignancy of pulmonary lesions].

OBJECTIVE: To evaluate the performance of FDG dual-head tomography with coincidence (DHTC) imaging and serum tumor marker assays in identifying lung carcinoma in 160 patients with abnormal findings on chest radiography. METHODS: A prospective evaluation of FDG imaging with DHTC and the measurement of 3 serum tumor markers for lung cancer (carcinoembryonic antigen, CYFRA21-1 and neuron specific enolase) were performed in two weeks in 160 consecutive patients with known or suspected lung malignancy. All images were analyzed visually, and the count ratio of tumor to normal tissue (T/N ratio) was calculated. It was considered positive if the FDG uptake was increased relative to that in the adjacent lung tissue, and the uptake was focal and the T/N ratio > or = 1.3. The serum tumor marker test was considered positive for malignancy if the serum level of at least 1 marker was elevated. RESULTS: 127 patients were proven to have lung cancer by pathology, and 33 patients had benign lung disease. The sensitivity, specificity and accuracy of FDG DHTC in assessing lung cancer were 94.5%, 84.8% and 92.5%, respectively, and those of the serum tumor markers were 67.7%, 84.8% and 71.3%, respectively. FDG DHTC showed significantly higher sensitivity (P < 0.001) and accuracy (P < 0.001) than serum tumor markers. Four patients with lung cancer had negative findings on FDG DHTC but had positive serum markers. CONCLUSION: FDG DHTC imaging is a powerful tool for evaluating patients with lung lesions suggestive of malignancy. Although the determination of serum tumor marker levels is less accurate than FDG DHTC, the combination of a positive FDG result and positive tumor markers may be helpful in improving the diagnosis of lung cancer.

Adult↗

PubMed2002

The mechanism underlying T cell help for induction of an antigen-specific in vivo humoral immune response to intact Streptococcus pneumoniae is dependent on the type of antigen.

Little is known concerning the role of T cells in regulating an anti-polysaccharide Ig response to an intact pathogen. We previously reported that the in vivo Ig responses to Streptococcus pneumoniae (strain R36A), specific for pneumococcal surface protein A (PspA) and for the phosphorylcholine (PC) determinant of C-polysaccharide, were both dependent on TCR-alphabeta(+) T cells and B7-dependent costimulation, although only PspA-specific memory was generated. In this report, we show that the T cell help underlying these two Ag-specific Ig responses is distinct. Using H-Y-specific T cell transgenic mice made "nonleaky" by crossing with mice genetically deficient for TCR-alpha, we demonstrate that the T cell help for the anti-PC, in contrast to the anti-PspA, response is TCR-nonspecific and occurs normally in the absence of germinal center formation, although it is still dependent on B7-dependent costimulation. Consistent with these data, we demonstrate, using cathepsin S(-/-) mice, that although the anti-PC response is largely dependent on CD4(+) T cells, there is a reduced (or lack of) dependence, relative to the anti-PspA response, on the generation of new peptide-MHC class II complexes. In this regard, the T cell help for an optimal anti-PC response is delivered more rapidly than that required for an optimal anti-PspA response. Collectively, these data demonstrate a novel accelerated TCR-nonspecific B7-dependent form of T cell help for augmenting a polysaccharide-specific Ig response to an intact bacterium without the generation of memory.

Animals↗

PubMed2002

Dendritic cells pulsed with intact Streptococcus pneumoniae elicit both protein- and polysaccharide-specific immunoglobulin isotype responses in vivo through distinct mechanisms.

Immature bone marrow-derived myeloid dendritic cells (BMDCs) are induced to undergo phenotypic maturation and secretion of tumor necrosis factor (TNF)-alpha, interleukin (IL)-6, IL-12, and IL-10 when pulsed in vitro with intact Streptococcus pneumoniae. After transfer to naive mice, pulsed BMDCs induce immunoglobulin (Ig) isotype responses specific for both protein and polysaccharide pneumococcal antigens, having in common the requirement for viable BMDCs, T cells, and B7-dependent costimulation in the recipient mice. Whereas primary Ig isotype responses to bacterial proteins uniformly require BMDC expression of major histocompatibility complex class II, CD40, and B7, and the secretion of IL-6, but not IL-12, similar requirements for antipolysaccharide Ig responses were only observed for the IgG1 isotype.

Animals↗