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Biomedical subjects

Y Dong

Publications and source records attributed to Y Dong.

At least 37 records · Page 2Linked to original sources
PubMed2002

Identification of metastasis-associated genes in early stage non-small cell lung cancer by subtractive hybridization.

Non-small cell lung cancer (NSCLC) is a leading cause of death and a substantial fraction of patients with surgically resected disease ultimately dies due to distant metastasis. To identify gene expression differences in early stage adenocarcinoma that either did or did not metastasize within a 5-year period, we employed a subtractive hybridization strategy of pooled RNA from primary adenocarcinomas (stage I) of the lung. Individual clones (n=225) of the subtracted cDNA library were sequenced. Further analyses of mRNA expression levels in a cohort of 70 NSCLC patients (stage I to IIIA) showed that the metastasis association of the identified genes was stage and histology specific. Cox regression analyses identified two genes (EIF4A1, MALA1) to be independent prognostic parameters for patients' survival in stage I and II disease. These findings could help to identify early-stage NSCLC patients at high risk for the development of distant metastasis.

Biomarkers, Tumor↗
PubMed2002

[Identification of a protein interacting with apoptin from human leucocyte cDNA library by using yeast two-hybrid screening].

To screen the protein interacting with apoptin from human leucocyte cDNA library by using yeast two-hybrid system, four clones interacting with apoptin were identified. One of them was homologous with Nmi (N-Myc interaction protein). Cell co-immunoprecipitation showed that apoptin could bind to Nmi in mammalian cells. Apoptin mutants T1, T2 and T3 lacked the C-terminal 11 AA,33-46 AA and both,respectively. Apoptin mutants T2 and T3 failed to interact with Nmi, suggesting that its 33-46 AA was pivotal for the interaction. Apoptin mutant T1 still interacted with Nmi, suggesting that its C-terminal 11 AA was not essential for the interaction.

Capsid↗
PubMed2001

p53 gene transfer does not enhance E2F-1-mediated apoptosis in human colon cancer cells.

E2F-1 and p53 are sequence specific transcription factors that are intimately involved in the regulation of the cell cycle. In addition to their role in cell cycle control, both E2F-1 and p53 have been identified as tumor suppressors and mediators of apoptosis. We have shown previously that adenoviral-mediated E2F-1 overexpression induces efficient apoptosis in colon adenocarcinoma cells. Previous reports have suggested that E2F-1 and p53 cooperate to mediate apoptosis and therefore, in this study, we examined the efficacy of combination gene therapy using adenovirus vectors expressing E2F-1 and p53 in human colon adenocarcinoma cell lines, HT-29 and SW620 (both mutant p53). Cells were treated by mock infection or infection with adenoviral vectors expressing b-galactosidase (LacZ), E2F-1, p53 or a combination of E2F-1 and p53. IC25 concentrations of each virus were estimated and used for each treatment in order to detect any synergistic or cooperative effects on tumor cell death in the combination therapy. By 5 days post infection, E2F-1-overexpressing cells exhibited growth inhibition and approximately 40-50% cell death in both cell lines. Co-expression of p53 with E2F-1 abrogated E2F-1-mediated growth inhibition and cell death. Cell cycle analysis revealed that overexpression of E2F-1 resulted in an accumulation of cells in G2/M phase, while overexpression of p53 resulted in a G1 phase accumulation. However, co-expression of E2F-1 and p53 counteracted each other as fewer cells accumulated in G1 and G2/M when compared to either p53 or E2F-1 alone. Furthermore, co-expression of p53 with E2F-1 resulted in decreased levels of E2F-1 protein expression. Mechanistically, upregulation of the CDK inhibitory protein, p21(WAF1/CIP1), was demonstrated in HT-29 cells following overexpression of either E2F-1, p53 or the combination E2F-1/p53 therapy. However, in SW620 cells, only the cells infected with Ad-p53 alone or in combination resulted in upregulation of p21(WAF1/CIP1). These results suggest that p53 and p21(WAF1/CIP1) may cooperate to inhibit the expression and activity of E2F-1. In conclusion, combination adenoviral vector-mediated E2F-1 and p53 gene transfer was not therapeutically advantageous in this in vitro model of human colon adenocarcinoma.

Adenocarcinoma↗
PubMed2001

Atrial natriuretic peptide gene G664A polymorphism and the risk of ischemic cerebrovascular disease.

The atrial natriuretic peptide (ANP) gene may underlie stroke susceptibility and sensitivity to cerebral ischemia in an animal model of stroke. The authors investigate its role in humans by genotyping a polymorphism (G664A) in 436 patients with ischemic cerebrovascular disease and 295 community control subjects. The frequency of this variant was similar in both groups and across the different stroke subtypes. The ANP gene G664A polymorphism is therefore unlikely to be an important risk factor for ischemic stroke in this population.

Aged↗
PubMed2001

[Quantitative analysis of human herpes virus type 8 and expression of its genes in patients with multiple myeloma].

OBJECTIVE: To investigate if infection of human herpesvirus type 8 (HHV8) exists in Chinese patients with multiple myeloma (MM), and to identify the relationship between clinical manifestation and the viral load in bone marrow biopsy samples. METHODS: Real-time quantitative PCR was conducted to define the viral load of HHV8 in bone marrow biopsy samples from 23 patients with MM. Nested PCR was conducted to amplify the KS330(233)Bam fragment of HHV8 from peripheral blood mononuclear cells, bone marrow aspirates and bone marrow biopsy samples. RT-PCR was used to study the expression of suspected oncogenes: vIL-6 and vIRF-1 genes. Bone marrow biopsy samples of 5 patients with blood diseases other than MM and 5 patients with non-blood system diseases were used as controls. PCR product of BCBL-1 cell line was used as positive control. RESULTS: (1) The positive rate of HHV8 in bone marrow biopsy samples from patients with MM was 69.6% (16/23) by real-time fluorescence quantitative PCR, and 82.6% (19/23) by nested-PCR. 16 bone marrow samples positive by fluorescence quantitative were positive too by nested-PCR. However, 3 bone marrow samples positive by nested-PCR were negative by fluorescence quantative. HHV8 was positive in only one of the 25 bone marrow aspirates from patients with MM (4%) and in none of the 20 peripharal blood samples from patients with MM. PCR showed negative result in 7 bone marrow aspirates taken form 13 MM patients with positive result by fluorescence quantative PCR. HHV8 was negative in bone marrow biopsy samples from patients with other diseases. HHV8 was negative in the peripheral blood samples from 16 MM patients, among which 9 out of the 11 cases with bone marrow biopsy samples taken showed HHV8 positive by fluorescence quatative PCR. Bone marrow biopsy samples of all patients with other blood diseases and non-blood system diseases were HHV8 negative. RT-PCR showed that among 12 MM patients the expression rate of vIRF-1 was 83.3% (10/12), and expression rate of vIL-6 was 0. The PCR positive products tallied with the sequence of HHV8 DNA. Clinical analysis showed that all of the patients with negative results had had chemotherapy. CONCLUSION: There is a certain association between multiple myeloma pathogenesis and HHV8. In detection of HHVb, nested-PCR is more sensitive than fluorescence quantitaative PCR. The viral gene vILR-1 plays a certain role in the pathogenesis of MM.

Adult↗
PubMed2001

Graft survival in a rhesus renal transplant model after immunotoxin-mediated T-cell depletion is enhanced by mycophenolate and steroids.

BACKGROUND: Anti-CD3 immunotoxin (IT), a T-cell-depleting agent, prolongs survival of renal allografts in a rhesus monkey model without the need for long-term immunosuppression. In this study we sought to further prolong allograft survival by giving short-term conventional immunosuppression simultaneous with IT administration. METHODS: MHC class II mismatched, juvenile rhesus monkeys were paired as donor and recipient for renal transplantation. Recipients received two to three daily doses of IT starting on the day of transplantation. Additional immunosuppression was given for no more than 60 days. Graft function was monitored by serum creatinine and renal biopsies. Flow cytometry was used to monitor T-cell recovery. RESULTS: Graft survival time (GST) in animals receiving IT was prolonged compared with controls with 50% of IT-treated monkeys surviving >100 days. Animals treated with IT plus mycophenolate mofetil (MMF) and steroids had significantly enhanced GST (mean GST, 305 days) compared with those treated with IT alone (mean GST, 94 days). In contrast, addition of cyclosporine or 40-O-[2-Hydroxyethyl]rapamycin did not significantly increase graft survival time. A comparison among animals from all treatment groups with short (<100 days) and long (>100 days) GST demonstrated that those with the shorter GST had a higher blood T-cell count 2 weeks after transplantation. Full recovery of CD4+ T cells required longer than 6 months. CONCLUSIONS: A combination with MMF and steroids given for 4 days after renal allograft transplantation significantly increases GST in IT-treated monkeys. We hypothesize that MMF and steroids suppress the initial T-cell activation mediated by IT.

Animals↗
PubMed2001

Successful conversion from conventional immunosuppression to anti-CD154 monoclonal antibody costimulatory molecule blockade in rhesus renal allograft recipients.

BACKGROUND: Several conventional forms of immunosuppression have been shown to antagonize the efficacy of anti-CD154 monoclonal antibody- (mAb) based costimulatory molecule blockade immunotherapy. Our objective was to determine if allograft recipients treated with a conventional immunosuppressive regimen could be sequentially converted to anti-CD154 mAb monotherapy without compromising graft survival. METHODS: Outbred juvenile rhesus monkeys underwent renal allotransplantation from MHC-disparate donors. After a 60-day course of triple therapy immunosuppression with steroids, cyclosporine, and mycophenolate mofetil, monkeys were treated with: (1) cessation of all immunosuppression (control); (2) seven monthly doses of 20 mg/kg hu5C8 (maintenance), or; (3) 20 mg/kg hu5C8 on posttransplant days 60, 61, 64, 71, 79, and 88 followed by five monthly doses (induction+maintenance). Graft rejection was defined by elevation in serum creatinine>1.5 mg/dl combined with histologic evidence of rejection. RESULTS: Graft survival for the three groups were as follows: group 1 (control): 70, 75, >279 days; group 2 (maintenance): 83, 349, >293 days, and; group 3 (induction+maintenance): 355, >377, >314 days. Acute rejection developing in two of four monkeys after treatment with conventional immunosuppression was successfully reversed with intensive hu5C8 monotherapy. CONCLUSIONS: Renal allograft recipients can be successfully converted to CD154 blockade monotherapy after 60 days of conventional immunosuppression. An induction phase of anti-CD154 mAb appears to be necessary for optimal conversion. Therefore, although concurrent administration of conventional immunosuppressive agents including steroids and calcineurin inhibitors has been shown to inhibit the efficacy of CD154 blockade, sequential conversion from these agents to CD154 blockade appears to be effective.

Animals↗
PubMed2001

Cyclin D1-CDK4 complex, a possible critical factor for cell proliferation and prognosis in laryngeal squamous cell carcinomas.

Cyclin D1 and its catalytic partner CDK4 are known to play important roles in the G1/S checkpoint of the cell cycle. The complex formed by CDK4 and cyclin D1 has been strongly implicated in the control of cell proliferation and prognoses in human malignancies. We investigated the immunohistochemical expression of cyclin D1, CDK4 and proliferating cell nuclear antigen (PCNA) in 102 patients with laryngeal squamous cell carcinoma (LSCC). Cyclin D1 overexpression was observed in 59 cases (57.8%) of LSCC, and was significantly correlated with tumor site, tumor size, lymph node metastasis and advanced stage. CDK4 overexpression was observed in 48 cases (47.1%), and was significantly correlated with tumor size and advanced stage. Cyclin D1 and CDK4 expression was significantly associated with cell proliferation measured by PCNA (r = 0.812, p < 0.0001 and r = 0.725, p < 0.0001, respectively). The Kaplan-Meier analysis showed that cyclin D1 overexpression was significantly associated with disease-free survival and overall survival. CDK4 overexpression was significantly associated with overall survival. When cyclin D1 and CDK4 are combined, the patients with co-overexpression of cyclin D1-CDK4 revealed the poorest overall survival. Additionally, in early-stage (I-II) cases, co-overexpression of cyclin D1-CDK4 was also revealed to possess a significant prognostic role. By multivariate analysis, cyclin D1 overexpression, lymph node metastasis and advanced stage were independent prognostic factors for disease-free survival. Cyclin D1 overexpression, CDK4 overexpression, tumor grade, lymph node metastasis and advanced stage were independent prognostic factors for overall survival. These findings indicate that cyclin D1 and CDK4 overexpression and/or co-overexpression of these proteins may play a pivotal role in the biological behavior of LSCC and may provide a strong prognostic implication.

Adult↗
PubMed2001

The Smad3 protein is involved in TGF-beta inhibition of class II transactivator and class II MHC expression.

TGF-beta is a immunoregulatory cytokine that inhibits class II MHC expression in a variety of cell types. Previous studies have shown that the class II MHC transactivator (CIITA), a master regulator that controls class II MHC expression, is targeted by TGF-beta for repression of IFN-gamma-induced class II MHC expression in astrocytes. The mechanism(s) underlying the TGF-beta inhibitory effect is not understood. In this study, we demonstrate that TGF-beta inhibition of CIITA expression occurs at the transcriptional level, and that both constitutive and IFN-gamma-induced human CIITA type IV promoter activity is inhibited by TGF-beta. TGF-beta does not affect the signaling events that mediate IFN-gamma activation of CIITA expression; i.e, TGF-beta does not inhibit IFN-gamma-induced STAT-1alpha phosphorylation and/or DNA binding ability, nor is IFN-gamma induction of IFN regulatory factor affected. The inhibitory effect of TGF-beta on the type IV CIITA promoter is mediated through a promoter region within 80 bp from the transcription start site. Elimination of TGF-beta inhibition of class II MHC and CIITA expression in Smad3-deficient astrocytes, as well as restoration of the inhibitory effect by overexpression of the Smad3 protein, demonstrates that Smad3 is essential in mediating TGF-beta inhibition of CIITA and class II MHC expression.

5' Untranslated Regions↗
PubMed2001

Characterization of the biological activity of gamma-glutamyl-Se-methylselenocysteine: a novel, naturally occurring anticancer agent from garlic.

Gamma-glutamyl-Se-methylselenocysteine (GGMSC) has recently been identified as the major Se compound in natural garlic and selenized garlic. Our working hypothesis is that GGMSC serves primarily as a carrier of Se-methylselenocysteine (MSC), which has been demonstrated in past research to be a potent cancer chemopreventive agent in animal carcinogenesis bioassays. The present study was designed to examine the in vivo responses to GGMSC or MSC using a variety of biochemical and biological end points, including (a) urinary Se excretion as a function of bolus dose; (b) tissue Se accumulation profile; (c) anticancer efficacy; and (d) gene expression changes as determined by cDNA array analysis. Our results showed that like MSC, GGMSC was well absorbed p.o., with urinary excretion as the major route for eliminating excess Se. When fed chronically, the profile of Se accumulation in various tissues was very comparable after treatment with either GGMSC or MSC. In rats that had been challenged with a carcinogen, supplementation with either GGMSC or MSC resulted in a lower prevalence of premalignant lesions in the mammary gland, and fewer mammary carcinomas when these early lesions were allowed to progress. More importantly, we found that a short term GGMSC/MSC treatment schedule of 4 weeks immediately after carcinogen dosing was sufficient to provide significant cancer protection, even in the absence of a sustained exposure past the initial 4-week period. With the use of the Clontech Atlas Rat cDNA Array, we further discovered that the gene expression changes induced in mammary epithelial cells of rats that were given either GGMSC or MSC showed a high degree of concordance. On the basis of the collective biology, biochemistry, and molecular biology data, we conclude that GGMSC is an effective anticancer agent with a mechanism of action very similar to that of MSC.

Animals↗
PubMed2001

Parthenocarpic apple fruit production conferred by transposon insertion mutations in a MADS-box transcription factor.

Fruit development in higher plants normally requires pollination and fertilization to stimulate cell division of specific floral tissues. In some cases, parthenocarpic fruit development proceeds without either pollination or fertilization. Parthenocarpic fruit without seed has higher commercial value than seeded fruit. Several apple (Malus domestica) mutants (Rae Ime, Spencer Seedless and Wellington Bloomless) are known to produce only apetalous flowers that readily go on to develop into parthenocarpic fruit. Through genetics, a single recessive gene has been identified to control this trait in apple. Flower phenotypes of these apple mutants are strikingly similar to those of the Arabidopsis mutant pistillata (pi), which produces flowers where petals are transformed to sepals and stamens to carpels. In this study, we have cloned the apple PI homolog (MdPI) that shows 64% amino acid sequence identity and closely conserved intron positions and mRNA expression patterns to the Arabidopsis PI. We have identified that in the apetalous mutants MdPI has been mutated by a retrotransposon insertion in intron 4 in the case of Rae Ime and in intron 6 in the case of Spencer Seedless and Wellington Bloomless. The insertion apparently abolishes the normal expression of the MdPI gene. We conclude that the loss of function mutation in the MdPI MADS-box transcription factor confers parthenocarpic fruit development in these apple varieties and demonstrates another function for the MADS- box gene family. The knowledge generated here could be used to produce parthenocarpic fruit cultivars through genetic engineering.

Amino Acid Sequence↗
PubMed2001

Apoptosis: an early event in metastatic inefficiency.

Whereas large numbers of cells from a primary tumor may gain access to the circulation, few of them will give rise to metastases. The mechanism of elimination of these tumor cells, often termed "metastatic inefficiency," is poorly understood. In this study, we show that apoptosis in the lungs within 1-2 days of introduction of the cells is an important component of metastatic inefficiency. First, we show that death of transformed, metastatic rat embryo cells occurred via apoptosis in the lungs 24-48 h after injection into the circulation. Second, we show that Bcl-2 overexpression in these cells inhibited apoptosis in culture and also conferred resistance to apoptosis in vivo in the lungs 24-48 h after injection. This inhibition of apoptosis led to significantly more macroscopic metastases. Third, comparison between the extent of apoptosis by a poorly metastatic cell line to that by a highly metastatic cell line 24 h after injection in the lungs revealed more apoptosis by the poorly metastatic cell line. These results indicate that apoptosis, which occurs at 24-48 h after hematogenous dissemination in the lungs is an important determinant of metastatic inefficiency. Although prior work has shown an association between apoptosis in culture and metastasis in vivo, this work shows that apoptosis in vivo corresponds to decreased metastasis in vivo.

Animals↗
PubMed2001

Immune function of astrocytes.

Astrocytes are the major glial cell within the central nervous system (CNS) and have a number of important physiological properties related to CNS homeostasis. The aspect of astrocyte biology addressed in this review article is the astrocyte as an immunocompetent cell within the brain. The capacity of astrocytes to express class II major histocompatibility complex (MHC) antigens and costimulatory molecules (B7 and CD40) that are critical for antigen presentation and T-cell activation are discussed. The functional role of astrocytes as immune effector cells and how this may influence aspects of inflammation and immune reactivity within the brain follows, emphasizing the involvement of astrocytes in promoting Th2 responses. The ability of astrocytes to produce a wide array of chemokines and cytokines is discussed, with an emphasis on the immunological properties of these mediators. The significance of astrocytic antigen presentation and chemokine/cytokine production to neurological diseases with an immunological component is described.

Animals↗
PubMed2001

Implication of malignancy and prognosis of p27(kip1), Cyclin E, and Cdk2 expression in epithelial ovarian tumors.

OBJECTIVE: The aim of this study was to further evaluate whether the expression of p27(kip1), cyclin E, and cdk2 is related to the malignancy of ovarian tumors and whether their expressions, alone or in combination, are associated with prognosis in epithelial ovarian carcinoma. METHODS: Immunohistochemical analysis using anti-p27(kip1), anti-cyclinE, and anti-cdk2 antibodies was carried out for 103 cases consisting of benign, borderline, and malignant ovarian tumors, and Western blot analysis and cdk2 activity assay were performed in 26 fresh ovarian tumor samples. RESULTS: p27(kip1) expression was reduced in ovarian carcinomas in contrast to benign and borderline tumors. The expression of cyclin E and cdk2 gradually increased from benign to borderline to malignant tumors. Kaplan-Meier survival analysis showed that patients with p27(kip1) expression had a high overall survival rate. Patients with cyclin E overexpression had a low overall survival rate. When the combination of these proteins was analyzed, patients with the p27(kip1) (-)/cyclin E (++)/cdk2 (++) phenotype were significantly associated with the poorest overall survival. In multivariate Cox regression analysis, the combined phenotype of p27(kip1) (-)/cyclin E (++)/cdk2 (++) was independently related to poor prognosis. CONCLUSIONS: Our results suggest that loss of p27(kip1) expression and overexpression of cyclin E or cdk2 were significantly associated with malignancy in ovarian tumors. p27(kip1) and cyclin E proteins may be valuable prognostic factors for epithelial ovarian carcinoma patients. Furthermore, the combined evaluation of p27(kip1)/cyclin E/cdk2 may provide the most important prognostic implication.

Adolescent↗
PubMed2001

The study on intramyocardial calcium overload and apoptosis induced by coxsackievirus B3.

The isolated cardiac myocytes of rats were immediately infected by cosackievirus B3 (CVB3) to investigate the effects of such procedure on the cell cycle, apoptosis and intracellular ionized calcium (Ca2+ i) of cardiac myocytes. Newborn Balb/c murine cardiac myocytes were cultivated, then infected by CVB3. Intracellular Ca2+ i was measured by flow cytometer. The calcium in the medium for culturing cardiac myocytes was detected by using atom absorb spectrum test. It was found that CVB3 could markedly inhibit the differentiation and proliferation of the infected cardiac myocytes and induce the apoptosis. The intracellular Ca2+ i level in the infected group was significantly higher than in the control group (P < 0.01). The calcium concentration in the medium for culturing cardiac myocytes in the infected group was significantly lower than in the control group (P < 0.05). It was suggested that the apoptosis and intracellular calcium overload of the CVB3-affected cardiac myocytes are likely to play an important role in the pathogenesis of viral myocarditis.

Animals↗
PubMed2001

Clinical characteristics of transmitted transfusion virus infection in children.

Clinical characteristics of transmitted transfusion virus (TTV) infection and its pathogenicity in children were evaluated. Serum TTV DNA from 118 children (mean age: 7.8 +/- 2.8 years) was detected by nested PCR. The product of PCR was cloned and sequenced. The positive rate for serum TTV-DNA in 20 healthy children, 9 cases of acute hepatitis, 51 cases of chronic hepatitis, 24 cases of nephritis or nephrotic syndrome and 14 cases of hypoplastic anemia or acute leukemia was 20%, 11%, 29%, 42% and 21% respectively, but there was no significant difference in TTV-DNA frequency among them (P > 0.05). Of the 16 patients receiving immunosuppressive agent for a long time, 7 (44%) were positive for TTV-DNA, and of the 17 cases not receiving immunosuppressive agent, 5 (29%) were positive with the difference being not significant (P > 0.05). Essential characteristics were pathogen-carrier or asymptomatic infection in children with TTV infection. Long-term employment of immunosuppressive agent did not increase the incidence in TTV infection. There was still high prevalence in TTV infection in healthy children not receiving blood product, suggesting the possibility of non hematogenous transmitted transfusion in TTV transmission.

Carrier State↗
PubMed2001

The cardiovascular actions of omapatrilat in spontaneously hypertensive rats.

Omapatrilat is a newly developed vasopeptidase inhibitor that inhibits both angiotensin-converting enzyme (ACE) and neutral endopeptidase and has potent antihypertensive efficacy. However, the specific effect of omapatrilat on cardiac function and left ventricular hypertrophy with hypertension remains controversial. Therefore, we investigated the effect of omapatrilat on blood pressure, cardiac hypertrophy, and cardiac function in spontaneously hypertensive rats (SHR). Studies were performed in SHR that received vehicle (n = 9), omapatrilat (n = 10), or fosinopril (ACE inhibitor, n = 7) by daily gavage for 56 days. Systolic blood pressure (SBP) and mean blood pressure (MBP) were measured by tail plethysmography. Left ventricular fractional shortening and left ventricular mass were measured by echocardiography at day 56. Omapatrilat and fosinopril significantly decreased SBP and MBP from day 1 through day 56, and omapatrilat markedly reduced SBP and MBP compared with fosinopril from day 21 to day 56. Although both omapatrilat and fosinopril decreased left ventricular mass and left ventricular mass-to-body weight ratio with increased LV fractional shortening, omapatrilat had a more potent effect on the reduction of left ventricular mass and improvement of cardiac function. This study shows that in SHR, omapatrilat mediated a potent and stable antihypertensive effect and a reduction in left ventricular mass with improvement of cardiac function, compared with ACE inhibition alone.

Angiotensin-Converting Enzyme Inhibitors↗