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Biomedical subjects

Y Ge

Publications and source records attributed to Y Ge.

At least 19 recordsLinked to original sources
PubMed2006

Genetic profiling of the oral microbiota associated with severe early-childhood caries.

The determination of the composition of the microbial community in the oral cavity is usually based on cultivation methods; however, nearly half of the bacteria in the saliva and the dental plaque are not cultivable. In this study, we evaluated the difference in oral microbial diversity between children with severe early-childhood caries (S-ECC) and caries-free (CF) controls by means of a cultivation-independent approach called denaturing gradient gel electrophoresis (DGGE). Pooled dental plaque samples were collected from 20 children aged 2 to 8 years. Total microbial genomic DNA was isolated from those subjects, and a portion of the 16S rRNA gene locus was PCR amplified by using universal primers. We observed that the mean species richness of the bacterial population was greater in the CF children (n = 12) (42 +/- 3.7) than in the S-ECC children (n = 8) (35 +/- 4.3); the difference was statistically significant (P = 0.005). The overall diversity of plaque samples as measured by the Shannon index was 3.5 for the S-ECC group and 3.7 for the CF group (P = 0.004). Differences in DGGE profiles were distinguished on the basis of a cluster analysis. Sequence analysis of excised DGGE bands consisted of 2.7 phylotypes, on average. After adjusting for the number of observed bands, we estimated that the S-ECC group exhibited 94.5 total phylotypes and that the CF group exhibited 113.4. These results suggest that the microbial diversity and complexity of the microbial biota in dental plaque are significantly less in S-ECC children than in CF children.

Bacterial Typing Techniques↗
PubMed2006

The GATA site-dependent hemogen promoter is transcriptionally regulated by GATA1 in hematopoietic and leukemia cells.

Hemgn (a gene symbol for hemogen in mouse, EDAG in human and RP59 in rat) encodes a nuclear protein that is highly expressed in hematopoietic tissues and acute leukemia. To characterize its regulatory mechanisms, we examined the activities of a Hemgn promoter containing 2975 bp of 5' flanking sequence and 196 bp of 5' untranslated region (5' UTR) sequence both in vitro and in vivo: this promoter is preferentially activated in a hematopoietic cell line, not in nonhematopoietic cell lines, and is sufficient to drive the transcription of a lacZ transgene in hematopoietic tissues in transgenic mice. Mutagenesis analyses showed that the 5' UTR including two highly conserved GATA boxes is critical for the promoter activity. GATA1, not GATA2, binds to the GATA binding sites and transactivates the Hemgn promoter in a dose-dependent manner. Furthermore, the expression of human hemogen (EDAG) transcripts were closely correlated with levels of GATA1 transcripts in primary acute myeloid leukemia specimens. This study suggests that the Hemgn promoter contains critical regulatory elements for its transcription in hematopoietic tissues and Hemgn is a direct target of GATA1 in leukemia cells.

5' Untranslated Regions↗
PubMed2006

Characterization and application of two novel monoclonal antibodies against human OX40: costimulation of T cells and expression on tumor as well as normal gland tissues.

OX40, a membrane-bound molecule of the tumor-necrosis-factor-receptor superfamily, is a critical costimulatory receptor during the immune response. Here, we newly generated two specific mouse antihuman OX40 monoclonal antibodies (mAbs) (2G2 and 1F7), whose specificities are quite different from the available OX40 mAb (ACT35) by competition assay. It was also found that both mAbs could enhance the proliferation, activation and differentiation of T lymphocytes primed by anti-CD3 mAb. These results evidenced that both were functional antihuman OX40 mAbs. Furthermore, stained by 2G2 and 1F7, FCM and immunohistochemistry detected the constitutive expression of OX40 on tumor cell lines from epithelium, breast cancer and glioma tissues. Meanwhile, the non-tumor tissues (thyroid gland, stomach gland) were also found OX40 expression. These results suggested that OX40 is not only expressed in activated T cells, but also in some tumors as well as normal gland tissues. Such expression pattern indicated that OX40 may be a valuable surface antigen in unveiling its expression and function outside the immune system. Briefly, these novel antibodies may contribute to the evaluation of the mechanism of tumor metastasis and eventually shed light on further study of tumor immunotherapy and autoimmune diseases.

Animals↗
PubMed2006

Polymerase chain reaction-based denaturing gradient gel electrophoresis in the evaluation of oral microbiota.

BACKGROUND/AIMS: Clinical evaluation of oral microbial reduction after a standard prophylactic treatment has traditionally been based on bacterial cultivation methods. However, not all microbes in saliva or dental plaque can be cultivated. Polymerase chain reaction-based denaturing gradient gel electrophoresis (PCR-DGGE) is a cultivation-independent molecular fingerprinting technique that allows the assessment of the predominant bacterial species present in the oral cavity. This study sought to evaluate the oral microbial changes that occurred after a standard prophylactic treatment with a conventional oral care product using PCR-DGGE. METHODS: Twelve healthy adults participated in the study. Pooled plaque samples were collected at baseline, 24 h after prophylaxis (T1), and 4 days after toothbrushing with fluoride toothpaste (T4). The total microbial genomic DNA of the plaque was isolated. PCR was performed with a set of universal bacterial 16S rDNA primers. The PCR-amplified 16S rDNA fragments were separated by DGGE. The effects of the treatment and of dental brushing were assessed by comparing the PCR-DGGE fingerprinting profiles. RESULTS: The mean numbers of detected PCR amplicons were 22.3 +/- 6.1 for the baseline group, 13.0 +/- 3.1 for the T1 group, and 13.5 +/- 4.3 for the T4 group; the differences among the three groups were statistically significant (P < 0.01). The study also found a significant difference in the mean similarities of microbial profiles between the baseline and the treatment groups (P < 0.001). CONCLUSION: PCR-based DGGE has been shown to be an excellent means of rapidly and accurately assessing oral microbial changes in this clinical study.

Adult↗
PubMed2006

HLA-G polymorphism in a Chinese Han population with recurrent spontaneous abortion.

Reproduction is an important biological phenomenon posing an immunological paradox because the semiallogeneic fetus survives by evading maternal immune recognition. The detailed mechanisms behind this maternal-fetal immunotolerance remain elusive. Human leucocyte antigen (HLA)-G, a non-classical HLA class I antigen, initially identified as a molecule selectively expressed on extravillous cytotrophoblasts and first studied in the context of pregnancy, has long been supposed to play a critical role in fetal-maternal immunotolerance. To investigate the role of HLA-G polymorphism in this process and whether the HLA-G genotype is associated with an increased risk for a subsequent miscarriage, 69 women with three or more recurrent spontaneous abortions (RSA) and 146 fertile control women were genotyped for the HLA-G locus in this study. To our knowledge, this is the first report on HLA-G polymorphism in RSA and in normal fertile women from a Chinese Han population. Nine HLA-G alleles were detected in the fertile control group; however, the allele HLA-G*0103 was absent in the RSA group. No statistical significance was observed in the distribution of HLA-G alleles between the two groups. The frequency of the null allele HLA-G*0105 N in the RSA group and in normal fertile women is 0.7% and 1.4%, respectively. Our data suggested that there was no association of HLA-G polymorphism with RSA.

Abortion, Habitual↗
PubMed2005

A novel blocking monoclonal antibody recognizing a distinct epitope of human CD40 molecule.

CD40, a member of the tumor necrosis factor receptor superfamily, is an important costimulatory molecule during the immune response. Here, we report a blocking mouse antihuman CD40 monoclonal antibody, mAb 3G3, of which the specificity was verified by flow cytometry and Western blot. It was shown by competition test that 3G3 bound to a different site (epitope) of CD40 from the reported CD40 mAbs, including clone mAb89, 3B2, and 5C11. It was also found that mAb 3G3 could inhibit homotypic aggregation of Daudi cells induced by the agonistic anti-CD40 mAb 5C11. Furthermore, mAb 3G3 effectively inhibited the proliferation of peripheral blood mononuclear cells in mixed lymphocyte reaction assay. Finally, a sensitive and specific soluble CD40 (sCD40) ELISA kit was established by matching mAb 3G3 with 5C11, and it was found that the levels of sCD40 in sera from patients with immune disorders such as hyperthyroidism, chronic nephritis, and rheumatoid arthritis were obviously higher than those from normal individuals. Thus, this blocking anti-CD40 mAb provides a novel tool for the study of CD40.

Antibodies, Monoclonal↗
PubMed2005

Characterization and application of two novel monoclonal antibodies against 2IgB7-H3: expression analysis of 2IgB7-H3 on dendritic cells and tumor cells.

2IgB7-H3 has recently been identified as a new member of the B7 family. Its expression at the protein level remains largely unknown due to the lack of the specific monoclonal antibody (mAb). To characterize the expression of 2IgB7-H3, we newly generated two mouse antihuman 2IgB7-H3 mAbs (4H7 and 21D4). We found the constitutive expression of 2IgB7-H3 on a series of tumor cell lines. Furthermore, the expression was examined on monocyte-derived dendritic cells (Mo-DCs) and DCs from CD34(+) hematopoietic progenitor cells (HPC) by means of mAb staining. The results showed that 2IgB7-H3 was expressed on Mo-DCs at a high and stable level during differentiation in vitro. With the maturation of DCs from CD34(+) HPCs, the expression of the molecule was upregulated. However, the 2IgB7-H3 was not expressed on fresh isolated T and B lymphocytes, monocytes, or CD34(+) HPCs. These results suggested that 2IgB7-H3 may be a valuable surface antigen for the detection of DCs.

Animals↗
PubMed2004

Neuronal cell injury precedes brain atrophy in multiple sclerosis.

Global brain atrophy estimated using MRI and whole brain N-acetylaspartate (WBNAA) concentration measured with proton MR spectroscopy were obtained in 42 patients with relapsing-remitting multiple sclerosis and 41 matched control subjects. Patients exhibited cross-sectional atrophy (0.5%; p = 0.033) and WBNAA decline (1.8%/y; p = 0.005) vs disease duration. The 3.6-fold rate disparity between the two processes suggests that neuronal/axonal dysfunction (N-acetylaspartate decline) precedes parenchyma loss, not its consequence (i.e., is an earlier, more sensitive specific metric of the ongoing disease activity).

Adult↗
PubMed2004

Characterization and application of two novel monoclonal antibodies against CD40L: epitope and functional studies on cell membrane CD40L and studies on the origin of soluble serum CD40L.

CD40 ligand, a 33-kDa cell membrane molecule, a member of the tumor necrosis factor superfamily, is an important costimulatory molecule during immune response. Here, we report on two functional mouse anti-human CD40L monoclonal antibodies 1B1 and 4F1 characterized by flow cytometry, Western blotting, and competition assay. The antibodies bound to distinct CD40L epitopes and therefore resulted in different bioactivity. Both antibodies could induce CD4+ T-cell alloantigenic hyporesponsiveness ex vivo. The antibodies were matched to develop a two-site enzyme-linked immunosorbent assay (ELISA) for soluble CD40L (sCD40L). Using this ELISA assay, we found major differences between plasma and serum sCD40L levels. Because the count of platelet sharply decreased in aplastic anemia (AA) and idiopathic thrombocytopenic purpura (ITP), we further analyzed the sCD40L concentration in the plasma of AA and ITP patients. The results showed that the sCD40L in serum was much lower than that of healthy subjects. These data demonstrate that platelets seem to be a major contributor to sCD40L, though not the only source of sCD40L in serum.

Animals↗
PubMed2004

Characterization and functional study of five novel monoclonal antibodies against human OX40L highlight reverse signalling: enhancement of IgG production of B cells and promotion of maturation of DCs.

OX40 ligand (OX40L), a molecule originally identified as human gp34, is an important co-stimulatory molecule during immune response. In this study, we report on five functional mouse anti-human OX40L monoclonal antibodies named as 9H10, 4C12, 8D10, 4H4 and 1G1, characterized by means of flow cytometry, Western blot and competition assay. These monoclonal antibodies bound to distinct OX40L epitopes on activated B cells and dendritic cells (DCs) and two of them could suppress the proliferation of T lymphocytes co-stimulated by mature DCs. Furthermore, we demonstrated that our monoclonal antibodies, such as 9H10 and 4C12, could trigger OX40L reverse signal that enhanced IgG production of B cells and promoted maturation of DCs as evidenced by the upexpression of CD80, CD86, CD83 and CXCR4 and monoclonal antibody 9H10 could also promote anti-CD40 monoclonal-antibody-stimulated DCs in order to induce T cells to secrete more interleukin-2 and interferon-gamma, which suggested that OX40L signals could strengthen the effect of CD40 signals on promoting Th1 differentiation.

Animals↗
PubMed2002

Repeated massage-like stimulation induces long-term effects on nociception: contribution of oxytocinergic mechanisms.

Massage-like stroking induces acute antinociceptive effects that can be reversed by an oxytocin antagonist, indicating activation of oxytocin on endogenous pain controlling systems. We now demonstrate an increase in hindpaw withdrawal latencies (HWLs), in response to thermal and mechanical stimuli, which was present after six treatments of massage-like stroking every other day and which continued to increase through the remaining seven treatments. Repeated massage-like stroking also resulted in increased oxytocin-like immunoreactivity (oxytocin-LI) levels in plasma and periaquaductal grey matter (PAG). Furthermore, increases in HWLs were also present after injections of oxytocin into the PAG (0.1, 0.5 and 1.0 nmol). Intra-PAG oxytocin injection of 1 nmol followed by 1 or 20 nmol of naloxone attenuated the increments in HWL. Also, there was a dose-dependent attenuation of the oxytocin-induced antinociceptive effects following intra-PAG injection of the mu-opioid antagonist beta-funaltrexamine (beta-FNA) and the kappa-opioid antagonist nor-binaltorphimine (nor-BNI) but not the delta-antagonist naltrindole. The long-term antinociceptive effects of massage-like stroking may be attributed, at least partly, to the oxytocinergic system and its interaction with the opioid system, especially the mu- and the kappa-receptors in the PAG.

Afferent Pathways↗
PubMed2002

Cell death of olfactory receptor neurons in a rat with nasosinusitis infected artificially with Staphylococcus.

Nasosinusitis is a common cause of acquired hyposmia or anosmia. To study the apoptotic death of olfactory receptor neurons in nasosinusitis, we made an inflammation model in rat infected with Staphylococcus. The histochemical changes in olfactory epithelium were examined using antibodies against protein gene product 9.5 (PGP 9.5), single-strand DNA (ssDNA), Bcl-2 and Bax that might be involved in the apoptosis of olfactory receptor neurons. The thickness of olfactory epithelium and the number of ssDNA-labeled cells were evaluated in each post-treatment group and the results were analyzed by two-way analysis of variance (ANOVA) and post hoc tests. Hematoxylin-eosin staining showed that a severe inflammatory reaction had occurred on the infected side of the nasal cavity and sinus, but not on the non-infected side. However, apoptosis of olfactory receptor neurons occurred on both sides; the apoptosis on the non-infected side started later and behaved like a shadow curve similarly to the infected side. Repeated measures ANOVA showed significant differences of both the thickness of olfactory epithelium (P < 0.0001) and the number of ssDNA-labeled cells (P = 0.0339) in the epithelium between the infected side and non-infected side comparing treatment, time and their interactions. Bcl-2 and Bax were detected only on the infected side in the early stages. Thus, nasosinusitis induced the apoptosis of olfactory receptor neurons. However, the apoptosis occurred not only on the infected side, but also on the non-infected side with no significant inflammation. The Bcl-2/Bax family seems to play an important role in the apoptosis induced by infection, but not in the apoptosis on the non-infected side. The results suggest that mechanisms of apoptosis of olfactory receptor neurons on the infected side may differ from those on the non-infected side.

Analysis of Variance↗
PubMed2001

Steric hindrance as a basis for structure-based design of selective inhibitors of protein-tyrosine phosphatases.

Utilizing structure-based design, we have previously demonstrated that it is possible to obtain selective inhibitors of protein-tyrosine phosphatase 1B (PTP1B). A basic nitrogen was introduced into a general PTP inhibitor to form a salt bridge to Asp48 in PTP1B and simultaneously cause repulsion in PTPs containing an asparagine in the equivalent position [Iversen, L. F., et al. (2000) J. Biol. Chem. 275, 10300-10307]. Further, we have recently demonstrated that Gly259 in PTP1B forms the bottom of a gateway that allows easy access to the active site for a broad range of substrates, while bulky residues in the same position in other PTPs cause steric hindrance and reduced substrate recognition capacity [Peters, G. H., et al. (2000) J. Biol. Chem. 275, 18201-18209]. The current study was undertaken to investigate the feasibility of structure-based design, utilizing these differences in accessibility to the active site among various PTPs. We show that a general, low-molecular weight PTP inhibitor can be developed into a highly selective inhibitor for PTP1B and TC-PTP by introducing a substituent, which is designed to address the region around residues 258 and 259. Detailed enzyme kinetic analysis with a set of wild-type and mutant PTPs, X-ray protein crystallography, and molecular modeling studies confirmed that selectivity for PTP1B and TC-PTP was achieved due to steric hindrance imposed by bulky position 259 residues in other PTPs.

Animals↗
PubMed2001

Transcriptional regulation of cell-specific expression of the human cystathionine beta -synthase gene by differential binding of Sp1/Sp3 to the -1b promoter.

Cystathionine beta-synthase (CBS) catalyzes the condensation of serine and homocysteine to form cystathionine, an intermediate step in the synthesis of cysteine. We previously characterized the CBS -1b minimal promoter (-3792 to -3667) and found that Sp1/Sp3, nuclear factor Y, and USF-1 were involved in the regulation of basal promoter activity (Ge, Y., Konrad, M. A., Matherly, L. H., Taub, J. W. (2001) Biochem. J. 357, 97-105). In this study, the critical cis-elements and transcription factors in the CBS -1b upstream region (-4046 to -3792) were examined in HT1080 and HepG2 cells, which differ approximately 10-fold in levels of CBS transcripts transcribed from the CBS -1b promoter. In DNase I footprint and gel shift analyses and transient transfections of mutant CBS -1b promoter constructs into HT1080 and HepG2 cells, transcriptionally important roles for Sp1/Sp3 binding to three GC boxes and one GT box and for binding of myeloid zinc finger 1-like proteins to two myeloid zinc finger 1 elements were indicated. In gel shift assays, very low levels of Sp1/Sp3 DNA-protein complexes were detected in HT1080 cells compared with HepG2 cells despite comparable levels of nuclear factor Y and USF-1 binding and similar levels of Sp1 and Sp3 proteins on Western blots. Mixing of HT1080 and HepG2 nuclear extracts resulted in no difference in total Sp factor binding in gel shift assays, thus excluding a role for an unknown activator or inhibitor in the disparate Sp1/Sp3 binding between the lines. Increased Sp1/Sp3 binding in gel shift assays was observed upon treatment of HT1080 nuclear extracts with protein kinase A, and decreased Sp1/Sp3 binding resulted from treatment of HepG2 nuclear extracts with calf alkaline phosphatase, suggesting a role for changes in Sp1/Sp3 phosphorylation in transcription factor binding and transactivation of the CBS -1b promoter. Characterization of CBS promoter structure and function should clarify the molecular bases for variations in CBS gene expression in genetic diseases and the relationship between CBS and Down syndrome.

Base Sequence↗