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Biomedical subjects

Y Ke

Publications and source records attributed to Y Ke.

At least 91 records · Page 5Linked to original sources
PubMed1997

Isolation of and effector for metastasis-inducing DNAs from a human metastatic carcinoma cell line.

Benign rat mammary epithelial cells transfected with restriction enzyme-fragmented DNA from a human malignant metastatic cell line (Ca2-83) produces transfectants that yield metastatic tumours in syngeneic rats. The six metastasis-inducing DNAs (Met-DNAs) that have been isolated from such transfectants are subgene in size and do not code for any expressed mRNAs, but correspond to potential regulatory regions of human DNA from malignant, metastatic cells. In pilot studies the one Met-DNA tested is detectable in some human breast tumours but not in normal tissue. Transfection of all six Met-DNAs singly into the benign mammary epithelial cells causes enhanced expression of osteopontin, whilst transfection of cDNA for osteopontin also induces the metastatic state. These results show that short regulatory DNAs exist in human cancer cells that can induce metastatic spread via a common effector gene, osteopontin, in model rat mammary cell lines.

Animals↗
PubMed1997

Nonionic triblock copolymers facilitate delivery of exogenous proteins into the MHC class I and class II processing pathways.

Nonionic triblock copolymers are relatively nontoxic adjuvants that induce high-titer, long-lasting antibody responses. We have previously shown that these adjuvants also induce cell-mediated immunity including lymphokine production by CD4(+) T cells and cytolytic responses by CD8(+) T cells. These copolymers are thought to modulate hydrophobic adhesive interactions between antigens (Ag) and lymphoid cells. We sought to test the hypothesis that copolymers facilitate uptake of exogenous Ag by antigen-presenting cells (APC) using an in vitro model system. Our data show that nonionic triblock copolymers enhanced presentation of soluble ovalbumin (OVA) to the major histocompatibility complex (MHC) class II-restricted CD4(+) T cells and MHC class I-restricted CD8(+) T cells, respectively. Presentation of OVA via the class I pathway was enhanced by copolymers in both phagocytic and nonphagocytic APC. However, copolymers did not enhance binding of peptides to the MHC molecules on APC, presentation of endogenously synthesized Ag, or presentation of exogenous Ag delivered by electroporation. These results provide additional evidence that these nonionic triblock copolymers can serve as powerful adjuvants for augmenting both humoral and cell-mediated immunity to protein Ag.

Adjuvants, Immunologic↗
PubMed1997

Stem cells in prostatic epithelia.

The normal prostate is, structurally and functionally, a highly complex glandular tissue in which populations of epithelial and stromal cells interact, one with the other, and are under a constant state of proliferation, differentiation, elimination and selective secondary replenishment so that functional integrity of the tissue is maintained. The ability of normal prostatic tissue to maintain its structure and function is dependent upon retention of cells, generally regarded as 'stem cells', which are able to respond by proliferation and selective differentiation within a wide range of phenotypic alternatives. With respect to cells in the epithelial compartment, replenishment is possible at several levels from within distinct pathways of normal cellular differentiation. It is now appreciated that fully differentiated prostatic epithelial cells retain a far greater degree of phenotypic 'plasticity' than was earlier apparent from morphological examination of the intact tissue. This inherent plasticity, coupled with the ability of the intact tissue to respond to diverse environmental (particularly humoral) stimuli by regenerating a wide and divergent spectrum of functional prostatic epithelial phenotypes is its strength--but also its weakness. Disturbance and distortion of the homeostatic regulatory mechanisms, whether physical or humoral, which control the normal sequence of epithelial proliferation, differentiation and elimination exposes these cells, particularly multipotent 'stem cells', to an increased probability of genetic change, thus resulting in either transient, or permanent, neoplastic transformation.

Basement Membrane↗
PubMed1997

Differential expression of acidic and basic fibroblast growth factors in benign prostatic hyperplasia identified by immunohistochemistry.

OBJECTIVE: To detect the expression and to determine the relative cellular locations of the two peptide growth factors, acidic fibroblast growth factor (a-FGF) and basic (b)-FGF in tissues from human benign prostatic hyperplasia (BPH). MATERIALS AND METHODS: A series of 50 sequential and unselected cases of human BPH tissues, obtained after transurethral prostatectomy, was examined. Adjacent sections of formalin-fixed and paraffin wax-embedded tissues were stained immunohistochemically for expression of a-FGF and b-FGF using well-characterized and commercially available antibodies. The stained tissue sections were assessed for the cellular distribution of immunohistochemical products and analysed according to the relative intensity of staining as well as the spatial relationships of positively stained cells. RESULTS: Acidic-FGF was weakly expressed with a pancytoplasmic distribution within luminal glandular epithelial cells in regions of prostatic intra-epithelial neoplasia (both PIN I and II) but not by non-dysplastic normal or hyperplastic tissues. No expression of a-FGF was detected in basal epithelial cells or in the stromal compartment of any tissue examined. In contrast, b-FGF was strongly expressed within the cytoplasm of all basal epithelial cells, but not by luminal epithelial cells, in morphologically normal regions of all cases examined. Basal expression of b-FGF was diminished, or absent, in regions of mild epithelial dysplasia, particularly those strongly expressing a-FGF. Extensive nuclear and cytoplasmic expression of b-FGF occurred predominantly in smooth muscle-type stromal cells but not in all types of stromal cells. CONCLUSIONS: This study confirmed both a differential and a reciprocal expression of a- and b-FGF in non-dysplastic prostatic hyperplasia and in mildly dysplastic regions of prostatic tissues. While only small amounts of a-FGF were expressed in BPH, exclusively in the luminal epithelial compartment, its consistent appearance in PIN I and II suggests that it might contribute to the early stages of PIN. Conversely, b-FGF may be an important mediator of stromal-epithelial interaction during the pathogenesis of BPH. These results provide new information about the relative expression of these growth factors, particularly in the architectural relationships between different cell-types within normal and non-malignant prostatic tissues.

Epithelium↗
PubMed1997

[Mutation analysis of transforming growth factor-beta type II receptor gene in human gastric cancer tissues].

OBJECTIVE: Mutations which cause abarrent expression of transforming type II receptor (TGF-beta RII) are responsible for the escape of some tumor cells from growth control midiated by TGF-beta. Two mutation hot spots (cDNA 709-718, 1931-1936) have been reported on human colon cancer cell lines. To elucidate the situation of this gene in human gastric cancer, 44 gastric cancer tissues were examined for mutation at the two hot spots. METHODS: Genomic DNA extracted from the cancer tissues was PCR amplified and analysed by silver stain for single stranded conformation polymorphism. Positive samples were sequenced by dry-primer automatic sequencing method. RESULTS: The data revealed a deletion rate of 6.8% (3/44) of the 1st hot spot; CA insertion of the 2nd hot spot was not found in all 44 gastric cancer tissues. CONCLUSION: The mutation incidence of TGF-beta R II in human gastric cancer is low.

Humans↗
PubMed1996

Exogenous antigens gain access to the major histocompatibility complex class I processing pathway in B cells by receptor-mediated uptake.

Professional antigen-presenting cells, such as macrophages, dendritic cells, or B cells, take up soluble, exogenous antigens (Ags) and process them through the class II pathway. Several reports have shown that phagocytic macrophages also process particulate or soluble forms of exogenous Ag via the class I pathway. By contrast, B cells normally do not process soluble, exogenous Ag by way of the class I pathway unless Ags are directly introduced into the cytoplasm. Here we report that B cells present exogenous Ag via the class I pathway when Ags are taken up by receptor-mediated endocytosis. Thus, specialized methods of Ag uptake such as phagocytosis or receptor-mediated endocytosis deliver exogenous Ag into the class I pathway of Ag processing and presentation.

Animals↗
PubMed1996

Mutation analysis of the transforming growth factor beta type II receptor in sporadic human cancers of the pancreas, liver, and breast.

The transforming growth factor beta (TGF beta) binds the type II TGF beta growth factor receptor (TGF beta RII) to inhibit growth of most epithelial tissues. Most human colon cancers with microsatellite instability have frameshift mutations in two microsatellites within the TGF beta RII coding region; such mutations truncate the receptor to produce resistance to TGF beta. To investigate this pathway in other tissues, we surveyed sporadic human cancers of the pancreas, liver and breast to determine the frequency of microsatellite mutations in the TGF beta RII. We amplified genomic DNA segments containing two microsatellites plus 72% of domain XI of the serine-threonine kinase region. SSCP analysis showed no evidence of mutation in 32 sporadic cancers (12 pancreas, 10 liver, and 10 breast). We conclude that microsatellite mutations in TGF beta RII are uncommon in sporadic tumors of the pancreas, liver and breast.

Base Sequence↗
PubMed1996

Oral antigen inhibits priming of CD8+ CTL, CD4+ T cells, and antibody responses while activating CD8+ suppressor T cells.

We have been investigating the mechanisms by which exogenous protein Ags activate CD8+ T cells. Previously, we have shown that OVA primed CTL precursors in vivo if administered as an emulsion with an adjuvant such as CFA. Such CTLs inhibit development of Ab responses when adoptively transferred into syngeneic mice. Thus, CD8+ CTL are immunosuppressive. These studies were initiated to determine whether CD8+ suppressor T cells were cytolytic T cells. Oral administration of protein Ags is a well-established method for inducing tolerance in humoral and delayed hypersensitivity responses which is associated with development of CD8+ suppressor T cells. OVA was chosen as a model Ag because it has been used extensively in oral tolerance studies, and target cells expressing the OVA gene are well characterized. Our data show that multiple, intragastric doses of native OVA inhibited priming of CD8+ CTL precursors and also inhibited CD4+ T cells and Ab responses. Oral OVA inhibited CTL priming in mice immunized with OVA-loaded EL4 cells, OVA-expressing transfectants, or OVA in CFA. The observed tolerance is specific to the orally administered Ag. Although oral OVA did not prime CTL precursors, it did activate spleen cells that transferred unresponsiveness to naive syngeneic mice. Suppression was mediated by CD4-CD8+ T cells. These CD8+ suppressor T cells were phenotypically distinguished from CTL by reactivity with a mAb that recognizes activated suppressor T cells.

Administration, Oral↗
PubMed1996

2q-, a non-random chromosomal abnormality in human non-small-cell lung cancer.

Many cytogenetic studies have been carried out on human lung cancer. However the chromosomal alterations in human lung cancers are often complex, making it difficult to identify some abnormal chromosomes by routine cytogenetic studies. Using FISH (fluorescence in situ hybridization), we studied the alterations of chromosome 2, 3, and 17 in four human bronchial epithelial cell lines, two human non-small-cell lung cancer (NSCLC) cell lines, and 12 primary NSCLC specimens. 2q- was found in three out of four human bronchial epithelial cell lines, two NSCLC cell lines, and three out of seven primary NSCLC specimens tested. 3p- was noted in five cases of twelve primary NSCLC patients examined. 3p- was the first cytogenetic discovery and the most prominent abnormality in lung cancer. 2q- has rarely been reported in human lung cancer but loss of heterozygosity by RFLP analysis for 2q had been reported in human NSCLC. Our results indicate that 2q- was also a non-random chromosomal abnormality in the early stage of the development of human NSCLC. There would be one or more putative tumor suppressor gene(s) on the long arm of chromosome 2. Loss of the gene(s) presumably contributes to the carcinogenesis of human non-small-cell lung cancer.

Adult↗
PubMed1996

Integration of SV40 at 12q23 in SV40-immortalized human bronchial epithelial cells.

In four SV40-immortalized human bronchial epithelia] cell lines established in our laboratory, we identified the SV40 integration sites by fluorescence in situ hybridization. We found that in the late passage of all the four cell lines, SV40 integrated at 12q23. It is possible that only SV40 integration at 12q23 is necessary for the immortalization of human bronchial epithelial cells. Some DNA sequences or genes in the region, such as IGF-1, may be involved with a proliferative advantage of the cells with 12q23 SV40 integration.

Bronchi↗
PubMed1996

Splicing signals are required for S-phase regulation of the mouse thymidylate synthase gene.

The thymidylate synthase (TS) gene is expressed at a much higher level in cells undergoing DNA replication than in nondividing cells. In growth-stimulated mammalian cells, TS mRNA content increases 10 to 20-fold as cells progress from G1 through S phase. However, the rate of transcription of the TS gene does not increase during this interval, indicating that the gene is regulated at the posttranscriptional level. We have shown that both the promoter of the mouse TS gene and TS introns are necessary (although neither is sufficient) for S-phase-specific regulation of TS mRNA content. In the present study, we examined in more detail the role of introns in regulating TS mRNA levels in growth-stimulated cells. TS minigenes that contain normal or modified introns were stably transfected into mouse 3T6 fibroblasts, and the regulation of the minigenes was compared with that of the endogenous TS gene. TS minigenes that contain TS intron 1 or 2 maintain S-phase regulation. Deletion of most of the interior of the introns had only minor effects on regulation. However, when splicing of the intron was inhibited by alteration of the splice donor and acceptor sites, the minigene was expressed at a constant level following growth stimulation. Minigenes consisting of the TS promoter linked to either a luciferase or a human beta-globin indicator gene were growth regulated when spliceable introns were included in the minigenes. However, when the introns were eliminated, the minigenes were expressed at a constant level. These observations indicate that the splicing reaction itself, rather than a control sequence within the intron, is important for growth-regulated expression of the TS gene. Possible mechanisms to account for the dual requirement for the TS promoter and intron splicing for proper regulation of the TS gene are discussed.

Animals↗
PubMed1996

[Activation of proto-oncogenes induced by MNNG on primary culture of human gastric epithelium and immortalized human gastric epithelial cell line].

Epidemiologic study has shown the association of nitrosamide compounds with the high incidence of stomach cancer in south China. To study the mechanism of gastric carcinogenesis, we have established an immortalized human gastric epithelial cell line GES-1. GES-1 cells and the normal gastric tissues were treated with different concentrations of MNNG for 24 hours. Point mutation at codon 12 of c-Ha-ras gene was found in cells and tissues (43%) as demonstrated by PCR-RFLP. Rearrangement of c-met gene and amplification of c-erbB2 gene were detected by Southern blot assay on the MNNG treated GES-1 cells. The results indicate that MNNG treatment was intimately associated with the activation of certain oncogenes. H-ras and c-met genes, serving as early targets of carcinogens may play important role in the carcinogenesis of human gastric epithelial cells.

Cell Transformation, Neoplastic↗
PubMed1996

[Detection of bacterial vaginosis in gram stained vaginal smears and papanicolaou stained cervical smears].

OBJECTIVE: To determine the sensitivity and specificity of diagnosis of bacterial vaginosis (BV) by papanicolaou (PAP)-stained cervical smears and gram-stained vaginal smears according to clinical criteria. METHODS: In the prospective study of 196 non-pregnant women of child-bearing age, 94 were clinically diagnosed to have BV. Gram-stained vaginal smears and PAP-stained cervical smears were collected from all enrolled patients. RESULTS: In comparison with clinical diagnosis of BV, the sensitivity and specificity of gram-stained vaginal smears and PAP-stained cervical smears were 94.7% (89/94), 98.0% (100/102) 85.1% (80/94), and 95.1% (97/102). The characteristics of BV in gram-stained vaginal smears and PAP-stained cervical smears included small bacteria of Gardnerella and bacteroides morphotypes and curved gram variable rods and absence of bacteria of Lactobacillus morphotypes. CONCLUSION: It is possible to screen and manage BV according to Gram-stained vaginal smears or PAP-stained cervical smears.

Adult↗
PubMed1996

Phacoemulsification and posterior chamber intraocular lens implantation.

OBJECTIVE: The study was designed to evaluate the therapeutic effects of phacoemulsification and PMMA posterior chamber intraocular lens implantation. METHODS: The surgery was performed on 74 eyes of 67 patients with senile, complicated and congenital cataracts. RESULTS: Post-operatively, the visual acuities with spherical correction or without correction were 0.5 or better in 80.5% at one week and with correction, in 97.6% at three months. The mean astigmatism was 1.90 +/- 1.15 D at one week and 0.93 +/- 0.55 D at three months which were respectively less than that in the control group with a 10-12 mm large incision (P < 0.001), but almost the same as that in the control group with a small incision and manual nucleus division technique (P > 0.05). The main complications were iris bite in 6 eyes, capsular rupture in 2 eyes and aseptic hypopyon in one eye. The selection of cases, surgical techniques and management of intraoperative complications were discussed. CONCLUSION: These results suggest that phacoemulsification be applied extensively. However, that it has more complications and risk must be emphasized for a beginner.

Adult↗
PubMed1996

[Glucocorticoid-induced apoptosis of human gastric epithelial cells transfected with p53 genes].

To investigate the apoptosis-inducing effect of glucocorticoid on gastric epithelial cell expressing different p53 genes, a human gastric epithelial cell line-GES-1 was transfected with either wild type or mutant p53 cDNA in vitro. The cells were treated with hydrocortisone in a concentration range of 0.2-0.8 g/L. Apoptotic cells were found in those transfectants. The apoptotic response of the wild-type p53-transfected GES-1 cells was much more marked than that of the mutant p53 transfected ones. It can be inferred that the glucocorticoid secreted not only suppress the immunological response during inflammation, but induce gastric epithelial cell apoptosis as well. If the gastric epithelial cell contains mutant p53 genes, the glucocorticoid confer a selective growth advantage which advance the malignant process.

Apoptosis↗
PubMed1995

Regulation of mouse thymidylate synthase gene expression in growth-stimulated cells: upstream S phase control elements are indistinguishable from the essential promoter elements.

Expression of the mammalian thymidylate synthase (TS) gene in growth-stimulated cells is closely coordinated with entry into S phase. Previous studies with transfected TS minigenes have shown that sequences upstream of the coding region as well as an intron in the transcribed region are both necessary for proper regulation of TS mRNA content in growth-stimulated cells. The goal of the present study was to identify the upstream regulatory elements. Minigenes consisting of TS 5' flanking sequences linked to the TS coding region (interrupted by introns 1 and 2) were stably transfected into mouse 3T6 cells. Deletion and site-directed mutagenesis of the 5' flanking region revealed that there is a close correspondence between the upstream sequences that are necessary for S phase regulation and the 30 nucleotide region that is essential for promoter activity. These observations raised the possibility that regulation of the TS gene occurs at the transcriptional level. However, nuclear run-on assays showed that the rate of transcription of the TS gene changed very little during the G1-S phase transition. Furthermore, when the TS promoter was linked to an intron-less luciferase indicator gene, there was no change in expression following growth-stimulation. Therefore it appears that the TS gene is controlled primarily at the posttranscriptional level, and that the TS essential promoter region is necessary (although not sufficient) for proper S phase regulation.

Animals↗
PubMed1995

A novel cell-cycle-dependent 350-kDa nuclear protein: C-terminal domain sufficient for nuclear localization.

We have screened human scleroderma patients for immunoreactivity with the components of the nucleus and the mitotic apparatus. We announce the identification of a novel cell-cycle-dependent nuclear protein using serum from a CREST patient AH. AH protein first appears at the nucleus of G2-phase and associates with the centrosome throughout the cell cycle. As chromosomes condense during the prophase, AH protein becomes enriched at the kinetochores. During mitosis, AH protein progressively disperses from the kinetochore and becomes diffusely localized in the cytoplasm and in telophase; it appears to be enriched within the intracellular bridge. Molecular cloning and transfection studies reveal that the 350-kDa AH protein contains a coiled-coil and a globular domain at the C-terminus that is sufficient for nuclear localization.

Amino Acid Sequence↗