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Duff MC, Hunter DB, Hobbs DT, Fink SD, Dai Z, Bradley JP. Mechanisms of strontium and uranium removal from high-level radioactive waste simulant solutions by the sorbent monosodium titanate. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2004; 38:5201-5207. [PMID: 15506218 DOI: 10.1021/es035415+] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
High-level waste (HLW) is a waste associated with the dissolution of spent nuclear fuel for the recovery of weapons-grade material. It is the priority problem for the U.S. Department of Energy's Environmental Management Program. Current HLW treatment processes at the Savannah River Site (Aiken, SC) include the use of monosodium titanate (MST, with a similar stoichiometry to NaTi2O5 x xH2O) to concentrate strontium (Sr) and actinides. The high affinity of MST for Sr and actinides in HLW solutions rich in Na+ is poorly understood. Mechanistic information about the nature of radionuclide uptake will provide insight about MST treatment reliability. Our study characterized the morphology of MST and the chemistry of sorbed Sr2+ and uranium [U(VI)] as uranyl ion, UO2(2+), on MST, which were added (individually) from stock solutions of Sr and 238U(VI) with spectroscopic and transmission electron microscopic techniques. The local structure of sorbed U varied with loading, but the local structure of Sr did not vary with loading. Sorbed Sr exhibited specific adsorption as partially hydrated species whereas sorbed U exhibited specific adsorption as monomeric and dimeric U(VI)-carbonate complexes. Sorption proved site specific. These differences in site specificity and sorption mechanism may account forthe difficulties associated with predicting Sr and U loading and removal kinetics using MST.
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Smiraglia DJ, Smith LT, Lang JC, Rush LJ, Dai Z, Schuller DE, Plass C. Differential targets of CpG island hypermethylation in primary and metastatic head and neck squamous cell carcinoma (HNSCC). J Med Genet 2003; 40:25-33. [PMID: 12525538 PMCID: PMC1735270 DOI: 10.1136/jmg.40.1.25] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Head and neck squamous cell carcinomas (HNSCC) often metastasise to the cervical lymph nodes. It is known for HNSCC as well as other cancers that progression from normal tissue to primary tumour and finally to metastatic tumour is characterised by an accumulation of genetic mutations. DNA methylation, an epigenetic modification, can result in loss of gene function in cancer, similar to genetic mutations such as deletions and point mutations. We have investigated the DNA methylation phenotypes of both primary HNSCC and metastatic tumours from 13 patients using restriction landmark genomic scanning (RLGS). With this technique, we were able to assess the methylation status of an average of nearly 1300 CpG islands for each tumour. We observed that the number of CpG islands hypermethylated in metastatic tumours is significantly greater than what is found in the primary tumours overall, but not in every patient. Interestingly, the data also clearly show that many loci methylated in a patient's primary tumour are no longer methylated in the metastatic tumour of the same patient. Thus, even though metastatic HNSCC methylate a greater proportion of CpG islands than do the primary tumours, they do so at different subsets of loci. These data show an unanticipated variability in the methylation state of loci in primary and metastatic HNSCCs within the same patient. We discuss two possible explanations for how different epigenetic events might arise between the primary tumour and the metastatic tumour of a person.
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103
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Dai Z, Lakkis FG. Cutting edge: Secondary lymphoid organs are essential for maintaining the CD4, but not CD8, naive T cell pool. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2001; 167:6711-5. [PMID: 11739484 DOI: 10.4049/jimmunol.167.12.6711] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Despite declining thymic output with age, the peripheral naive T cell pool of an adult animal remains remarkably stable. Therefore, a central question in immunology is how the naive T cell pool is maintained. Here we show that the maintenance of the naive CD4, but not CD8, T cell population in the thymectomized adult mouse is dependent on the presence of secondary lymphoid tissues. This finding is explained by the inability of naive CD4 T cells to sustain normal levels of the survival molecule Bcl-2 or to undergo homeostatic proliferation in the absence of secondary lymphoid organs. Thus, naive CD4 T cells must traffic through secondary lymphoid organs to maintain a stable CD4 pool while naive CD8 T cells encounter their survival and proliferation signals outside the organized structures of secondary lymphoid tissues.
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104
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Zhao D, Dai Z, Zhou K, Zhang L. [Expression of the artificial cecropin CMIV-like gene of Chinese silkworm Bombyx mori in Laphygma exigua larvae]. WEI SHENG WU XUE BAO = ACTA MICROBIOLOGICA SINICA 2001; 41:680-5. [PMID: 12552823] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/28/2023]
Abstract
The synthesized CMIV-like Gene was linked with the signal peptide gene of nature silkworm antibacterial peptide and was inserted into baculovirus expression vector pFastBac 1, construcing a recombinant transposing vector. The vector was transformed into DH10Bac competent E. coli cells. The recombinant Bacmid was obtained. The recombinant Bacmid was transfected into sf21 cells to get the recombinant virus. Laphygma exigua larvae were infected with the recombinant virus to express the antibacterial peptide. The hemolymph were tested to have antibacterial activity. The active antibacterial peptide was purified by acid polyacrylamide electrophoresis. The specific expression of mRNA of CMIV-like Gene was tested using Northern blotting.
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105
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Zhu WG, Dai Z, Ding H, Srinivasan K, Hall J, Duan W, Villalona-Calero MA, Plass C, Otterson GA. Increased expression of unmethylated CDKN2D by 5-aza-2'-deoxycytidine in human lung cancer cells. Oncogene 2001; 20:7787-96. [PMID: 11753657 DOI: 10.1038/sj.onc.1204970] [Citation(s) in RCA: 87] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2001] [Revised: 09/05/2001] [Accepted: 09/13/2001] [Indexed: 11/09/2022]
Abstract
DNA hypermethylation of CpG islands in the promoter region of genes is associated with transcriptional silencing. Treatment with hypo-methylating agents can lead to expression of these silenced genes. However, whether inhibition of DNA methylation influences the expression of unmethylated genes has not been extensively studied. We analysed the methylation status of CDKN2A and CDKN2D in human lung cancer cell lines and demonstrated that the CDKN2A CpG island is methylated, whereas CDKN2D is unmethylated. Treatment of cells with 5-aza-2'-deoxycytidine (5-Aza-CdR), an inhibitor of DNA methyltransferase 1, induced a dose and duration dependent increased expression of both p16(INK4a) and p19(INK4d), the products of CDKN2A and CDKN2D, respectively. These data indicate that global DNA demethylation not only influences the expression of methylated genes but also of unmethylated genes. Histone acetylation is linked to methylation induced transcriptional silencing. Depsipeptide, an inhibitor of histone deacetylase, acts synergistically with 5-Aza-CdR in inducing expression of p16(INK4a) and p19(INK4d). However, when cells were treated with higher concentrations of 5-Aza-CdR and depsipeptide, p16(INK4a) expression was decreased together with significant suppression of cell growth. Interestingly, p19(INK4d) expression was enhanced even more by the higher concentrations of 5-Aza-CdR and depsipeptide. Our data suggest that p19(INK4d) plays a distinct role from other INK4 family members in response to the cytotoxicity induced by inhibition of DNA methylation and histone deacetylation.
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106
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Dai Z, Yu X. [Yu Jinghe's Chronicle]. ZHONGHUA YI SHI ZA ZHI (BEIJING, CHINA : 1980) 2001; 27:52-6. [PMID: 11618968] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/21/2023]
Abstract
The life and origin of medical learning from family of Yu Jinghe, renowned doctor of the Qing Dynasty, are described here in the form of chronicle. He was born in Yixing, Jiangsu. His parent died when he was a boy and he joined the Taiping Army for 5 years with difficult experiences. Later, he moved to Menghe and learned pharmacology from his elder brother. His works include Yu's Annotation on Shanghanlun Yi, Collection of Case Records on External Diseases, Collection After Practising Hour etc. Moreover, Yu's descendents and his close relationship with other modern celebrated doctors such as Ding Ganren and his son Ding Zhongying, and Yun Tieqiao are also mentioned.
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107
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Dai Z, Xu X, Chen Q. [Defective expression of B7.2 in B cell chronic lymphocytic leukemia B cells]. ZHONGHUA YI XUE ZA ZHI 2001; 81:1062-5. [PMID: 11758257] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/23/2023]
Abstract
OBJECTIVE To investigate the expression of B7.1 and B7.2 molecules in peripheral B cells of patients with chronic B cell lymphocytic leukemia (BCLL) and to study the relationship between B7.1 and B7.2 expression and pathogenic mechanism of BCLL. METHODS Peripheral blood mononuclear cells (PBMC) were separated by Ficoll-Hypaque lymphocytes separation medium from 25 normal persons (normal control group) and 23 BCLL patients (BCLL group) which were further divided into two groups, phase 0-II group and phase III-IV group. Flow cytometry (FCM) was used to analyze the B7.1 and B7.2 expression in peripheral B cells after the mononuclear cells had been cultured for 24 hours in vitro. RESULTS The B7.2 expression in B cells of BCLL patients was significantly lower than that in normal control group (P < 0.05). No statistically significant difference was found in the B7.1 expression and co-expression of B7.1 and B7.2 between the BCLL group and normal control group. The average B7.2 expression rates in patients of phase 0-II group and phase III-IV group were 25% +/- 17% and 17% +/- 8% respectively without statistically significant difference. CONCLUSION The B7.2 expression in B cell of patients with BCLL is defective, which may be one of the pathogenic mechanisms of chronic BCLL and a major cause why the body fails to clear the BCLL cells via immunological means.
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108
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Schwebach JR, Casadevall A, Schneerson R, Dai Z, Wang X, Robbins JB, Glatman-Freedman A. Expression of a Mycobacterium tuberculosis arabinomannan antigen in vitro and in vivo. Infect Immun 2001; 69:5671-8. [PMID: 11500443 PMCID: PMC98683 DOI: 10.1128/iai.69.9.5671-5678.2001] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The outermost layer of Mycobacterium tuberculosis contains two major polysaccharides, arabinomannan (AM) and glucan (GC). We studied the in vitro and in vivo expression of an M. tuberculosis AM antigen using monoclonal antibody (MAb) 9d8 (2a), an isotype-switched variant of the immunoglobulin G3 (IgG3) MAb 9d8. MAb 9d8 had been previously shown to bind M. tuberculosis AM and the M. tuberculosis surface. Our in vitro experiments showed that MAb 9d8(2a) bound strongly to whole-cell M. tuberculosis Erdman but not to the CDC 1551 strain grown in medium for an extended period. However, AM antigen was detected in the culture supernatant of both strains, and its concentration increased in a time-dependent manner. The detection of AM antigen from both strains was decreased in the presence of Tween 80. In mice infected with M. tuberculosis Erdman, AM antigen accumulated in organ homogenates concomitant to an increase in bacterial organ burden and an increase in IgG and IgM titer to AM. These results (i) indicate that the surface expression of AM during in vitro growth changes with culture age, is strain dependent, and is affected by the presence of Tween 80 in the culture media; (ii) show that AM is produced by bacteria growth in vivo; and (iii) demonstrate that the amount of in vivo-detected AM can be dependent on the number of bacteria in the infected organ.
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109
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Frühwald MC, O'Dorisio MS, Dai Z, Tanner SM, Balster DA, Gao X, Wright FA, Plass C. Aberrant promoter methylation of previously unidentified target genes is a common abnormality in medulloblastomas--implications for tumor biology and potential clinical utility. Oncogene 2001; 20:5033-42. [PMID: 11526488 DOI: 10.1038/sj.onc.1204613] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2000] [Revised: 05/08/2001] [Accepted: 05/09/2001] [Indexed: 11/08/2022]
Abstract
Medulloblastomas exhibit an array of diverse cytogenetic abnormalities. To evaluate the significance of epigenetic rather than genetic lesions in medulloblastomas and other primitive neuroectodermal tumors (PNETs) of the childhood CNS we performed a systematic analysis of gene specific and global methylation. Methylation-specific PCR detected no methylation for p15(INK4B), von Hippel Lindau and TP53 and only limited methylation for E-Cadherin and p16(INK4A) in tumors. The cell lines Daoy and MHH-PNET-5 in which the p16(INK4A) promoter was methylated did not express the gene, but demonstrated abnormalities by SSCP. Immunohistochemistry for p16 was negative in all examined normal cerebella and medulloblastomas. Using the technique of Restriction Landmark Genomic Scanning we detected methylation affecting up to 1% of all CpG islands in primary MB/PNETs and 6% in MB cell lines. Methylation patterns differed between medulloblastomas and PNETs. Examination of several methylated sequences revealed homologies to known genes and expressed sequences. Analysis of survival data identified seven of 30 hypermethylated sequences significantly correlating with poor prognosis. We suggest that DNA hypermethylation has an outstanding potential for the identification of novel tumor suppressors as well as diagnostic and therapeutic targets in MBs and other PNETs of the CNS.
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110
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Dai Z, Kerzic P, Schroeder WG, McNiece IK. Deletion of the Src homology 3 domain and C-terminal proline-rich sequences in Bcr-Abl prevents Abl interactor 2 degradation and spontaneous cell migration and impairs leukemogenesis. J Biol Chem 2001; 276:28954-60. [PMID: 11387320 DOI: 10.1074/jbc.m101170200] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
The hematopoietic cells from patients with Bcr-Abl-positive chronic myelogenous leukemia exhibit multiple abnormalities of cytoskeletal function. The molecular events leading to these abnormalities are not fully understood. Previously we showed that Bcr-Abl elicits ubiquitin-dependent degradation of Abl interactor proteins. Because recent studies have suggested a role of Abl interactor proteins in the pathway that regulates cytoskeletal function, we investigated whether mutations in Bcr-Abl that interfere with the signaling to Abl interactor proteins affect its leukemogenic activity. We report here that the Src homology 3 domain and C-terminal proline-rich sequences of Bcr-Abl are required for its binding to Abl interactor 2 as well as for the induction of Abl interactor 2 degradation. Although the deletion of these regions did not affect the ability of the mutant Bcr-Abl to transform hematopoietic cells to growth factor independence, it abrogated its ability to stimulate spontaneous cell migration on fibronectin-coated surfaces. Furthermore, the mutant Bcr-Abl, defective in binding to Abl interactor 2 and inducing its degradation, failed to induce chronic myelogenous leukemia-like disease in mouse. These results are consistent with a role of Abl interactor proteins in the regulation of cytoskeletal function as well as in the pathogenesis of Bcr-Abl-induced leukemogenesis.
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MESH Headings
- Adaptor Proteins, Signal Transducing
- Amino Acid Sequence
- Animals
- Bone Marrow Transplantation/pathology
- Cell Line
- Chemotaxis
- Fibronectins/physiology
- Fusion Proteins, bcr-abl/chemistry
- Fusion Proteins, bcr-abl/genetics
- Fusion Proteins, bcr-abl/metabolism
- Homeodomain Proteins/metabolism
- Humans
- Leukemia, Myelogenous, Chronic, BCR-ABL Positive/genetics
- Leukemia, Myelogenous, Chronic, BCR-ABL Positive/pathology
- Male
- Mice
- Mice, Inbred C57BL
- Mice, Inbred DBA
- Mice, Transgenic
- Mutagenesis
- Peptide Fragments/chemistry
- Peptide Fragments/metabolism
- Proline
- Recombinant Proteins/chemistry
- Recombinant Proteins/metabolism
- Retroviridae/genetics
- Sequence Deletion
- Transfection
- Tumor Cells, Cultured
- Ubiquitins/metabolism
- src Homology Domains
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Frühwald MC, O'Dorisio MS, Smith L, Dai Z, Wright FA, Paulus W, Jürgens H, Plass C. [Hypermethylation as a potential prognostic factor and a clue to a better understanding of the molecular pathogenesis of medulloblastoma--results of a genomewide methylation scan]. KLINISCHE PADIATRIE 2001; 213:197-203. [PMID: 11528554 DOI: 10.1055/s-2001-16851] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
BACKGROUND The molecular mechanisms controlling initiation and progression of medulloblastomas are largely unclear. Changes in DNA methylation of promoter regions have been shown to disturb the expression of growth regulatory genes. PATIENTS AND METHODS We evaluated DNA methylation patterns in 17 medulloblastomas, 5 stPNETs and 5 medulloblastoma cell lines using Restriction Landmark Genomic Scanning (RLGS), a method displaying up to 2.000 potential gene loci in a single gene. To test whether previously characterized tumor suppressor genes are affected by hypermethylation we performed MS-PCR for p15INK4B, p16INK4A, VHL, TP53 and E-cadherin. RESULTS The analysis of RLGS profiles from tumors revealed an abundance of hypermethylation in primary tumors and cell lines. Extrapolated to the human genome with its approximately 36,000 genes a total of 420 loci become hypermethylated in the tumor genomes. The previously characterized medulloblastoma breakpoint cluster in 17p11.2 appears to be a hotspot for aberrant methylation. Cox regression analysis of survival data identified seven CpG islands for which hypermethylation is suggestive of a poor prognosis. MS-PCR analysis of known genes demonstrated hypermethylation of p16INK4A in a limited number of tumors. The pattern of DNA hypermethylation was similar in medulloblastomas and stPNETs. However, some CpG islands were shown to be specific for a tumor type, while others were shared targets. CONCLUSIONS Hypermethylation is a common abnormality in primary medulloblastomas and supratentorial PNETs. Several hundreds of CpG islands are potential targets for methylation in medulloblastomas including the breakpoint cluster in 17p11.2. The methylation status of certain gene sequences appears to be associated with the clinical outcome. Promoter hypermethylation has an outstanding potential as a marker for the identification of novel tumor suppressors as well as diagnostic and therapeutic targets in medulloblastomas.
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112
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Smiraglia DJ, Rush LJ, Frühwald MC, Dai Z, Held WA, Costello JF, Lang JC, Eng C, Li B, Wright FA, Caligiuri MA, Plass C. Excessive CpG island hypermethylation in cancer cell lines versus primary human malignancies. Hum Mol Genet 2001; 10:1413-9. [PMID: 11440994 DOI: 10.1093/hmg/10.13.1413] [Citation(s) in RCA: 180] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Cancer cell lines are widely used in many types of cancer research, including studies aimed at understanding DNA hypermethylation of gene promoters in cancer. Hypermethylation of promoters is capable of repressing the expression of tumor suppressor genes and may play a role in the development and/or progression of cancer. Although both primary malignancies and cancer cell lines exhibit this epigenetic phenomenon, there has been no direct comparison between them. In order to address this question, we have utilized restriction landmark genomic scanning to measure the hypermethylation phenotypes of cancer cell lines and compared these data with the same analysis performed on primary malignancies. In all cases, cancer cell lines exhibit significantly higher levels of CpG island hypermethylation than the primary malignancies they represent. Colon cancer cell lines are most similar to their respective tumors, with only a 5-fold increase in hypermethylation, while head and neck squamous cell carcinoma cell lines show a 93-fold increase in hypermethylation. Furthermore, >57% of the loci methylated in cell lines are never methylated in 114 primary malignancies studied. Seventy percent of loci hypermethylated in cell lines are hypermethylated in lines from more than one type of cancer. These data indicate that most CpG island hypermethylation observed in cancer cell lines is due to an intrinsic property of cell lines as opposed to the malignant tissue from which they originated.
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113
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Rush LJ, Dai Z, Smiraglia DJ, Gao X, Wright FA, Frühwald M, Costello JF, Held WA, Yu L, Krahe R, Kolitz JE, Bloomfield CD, Caligiuri MA, Plass C. Novel methylation targets in de novo acute myeloid leukemia with prevalence of chromosome 11 loci. Blood 2001; 97:3226-33. [PMID: 11342453 DOI: 10.1182/blood.v97.10.3226] [Citation(s) in RCA: 66] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Aberrant DNA methylation is believed to be important in tumorigenesis by causing either transcriptional inactivation of genes or chromosomal instability. Several laboratories have identified promoter hypermethylation of tumor suppressor genes in acute myeloid leukemia (AML). However, these studies do not provide a global assessment of overall methylation changes and do not allow the identification of novel methylated sequences. Previously, nonrandom CpG island methylation was reported in 17 adult de novo AML diagnostic samples when compared with the corresponding remission samples by means of restriction landmark genomic scanning (RLGS). That study has been expanded on by an analysis of a larger set of CpG islands (1740 vs 1184), which now provides details of 33 cloned methylated loci, including 21 known genes or expressed sequence tags. Five of these cloned loci appear to be methylated only in AML and not in the 6 solid tumors studied in this study (more than 98 samples analyzed). Chromosomal location was available for 30 of the 33 loci, and 5 of these 30 (17%) are localized to chromosome 11, suggesting a trend toward overrepresentation of methylation events on this chromosome. These results provide evidence for widespread aberrant methylation in AML, with identification of novel methylation targets, epigenetic changes that appear unique to AML, and apparent preferential methylation on chromosome 11.
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García-Gutiérrez M, Missana T, Mingarro M, Samper J, Dai Z, Molinero J. Solute transport properties of compacted Ca-bentonite used in FEBEX project. JOURNAL OF CONTAMINANT HYDROLOGY 2001; 47:127-137. [PMID: 11288570 DOI: 10.1016/s0169-7722(00)00143-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The present Spanish concept of a deep geological high level waste repository includes an engineered clay barrier around the canister. The clay presents a very high sorption capability for radionuclides and a very small hydraulic conductivity, so that the migration process of solutes is limited by sorption and diffusion processes. Therefore, diffusion and distribution coefficients in compacted bentonite (i.e. in "realistic" liquid to solid ratio conditions) are the main parameters that have to be obtained in order to characterise solute transport that could be produced after the canister breakdown. Through-Diffusion (TD) and In-Diffusion (ID) experiments with HTO, Sr, Cs and Se were carried out using compacted FEBEX bentonite, which is the reference material for the Spanish concept of radioactive waste disposal. Experiments were interpreted by means of available analytical solutions that allow the estimation of diffusion coefficients and, in some cases, distribution coefficients. Analytical solutions are simple to use, but rely on hypotheses that do not hold in all the experiments. These experiments were interpreted also using an automatic parameter estimation code that overcomes the limitations of analytical solutions. Numerical interpretation allows the simultaneous estimation of porosity, diffusion and distribution coefficients, accounts for the role of porous sinters and time-varying boundary concentrations, and can use different types of raw concentration data.
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115
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Frühwald MC, O'Dorisio MS, Dai Z, Rush LJ, Krahe R, Smiraglia DJ, Pietsch T, Elsea SH, Plass C. Aberrant hypermethylation of the major breakpoint cluster region in 17p11.2 in medulloblastomas but not supratentorial PNETs. Genes Chromosomes Cancer 2001; 30:38-47. [PMID: 11107174] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/18/2023] Open
Abstract
Deletions of 17p have been consistently reported in up to 50% of medulloblastomas (MBs), and the major breakpoint interval has been localized to chromosome segment 17p11.2. Based on several reports linking aberrant DNA methylation and chromosomal disruption, we examined the methylation pattern in this region by employing restriction landmark genomic scanning (RLGS). Several CpG islands located in the major breakpoint cluster region were identified using a bacterial artificial chromosome (BAC) contig of the breakpoint region. A long-range methylation map was established for 20 MBs and 5 supratentorial primitive neuroectodermal tumors (stPNETs). Selected CpG islands were examined using Southern and bisulfite sequencing analysis. Aberrantly hypermethylated CpG islands in 17p11. 2 were found in 33% of MBs. Interestingly, one CpG island was methylated in MBs, but not in any of the examined stPNETs. A BAC clone covering three of the methylated CpG islands was partially sequenced in the search for a potential tumor suppressor gene. None of the expressed sequence tag sequences and full-length mouse/human cDNAs that were associated with aberrant methylation showed a change in expression levels due to methylation. The potential link between chromosomal instability in 17p11.2 and hypermethylation in this region is discussed.
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116
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Guan J, Dai Z, Shen H. [Study on the correlation of estrogen receptor gene polymorphism to bone mineral density of radius in Chinese Han postmenopausal women in Beijing]. ZHONGHUA FU CHAN KE ZA ZHI 2001; 36:40-2. [PMID: 11778544] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/23/2023]
Abstract
OBJECTIVE To investigate the distribution of estrogen receptor (ER) gene polymorphism in postmenopausal Han women in Beijing as well as its correlation with bone mineral density (BMD) of radius. METHODS Xba I, and Pvu II polymorphism of ER gene were studied by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) in 99 healthy postmenopausal Han women. BMD of distal (spongy bone) and proximal (compact bone) radius were determined by dual-energy X-ray absorptiometry (DEXA) as well. The relationship between BMD and polymorphism of ER gene was analyzed by variance analysis. RESULTS Pvu II polymorphism of ER gene is not associated with BMD of both sites of radius (P > 0.05); while Xba I polymorphism of ER gene is significantly associated with BMD spongy and compact bone of radius (P < 0.05). Women with XX genotype have the lowest BMD T-score of -1.55 +/- 0.37 for the compact and -2.54 +/- 0.38 for the spongy, and those with xx genotype have the highest BMD T-score of -0.95 +/- 0.24 for compact and -1.74 +/- 0.16 for spongy. CONCLUSION There is a significant correlation of Xba I polymorphism of ER gene with BMD of distal and proximal radius. It is indicated that the difference in ER genotypes among individuals might influence the development of osteoporosis.
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117
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Dai Z, Yu R, Gong X, Wang S. [The analysis of the axises of corneal astigmatism and total astigmatism in astigmatic patients]. YAN KE XUE BAO = EYE SCIENCE 2000; 16:279-80. [PMID: 12579790] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 04/20/2023]
Abstract
PURPOSE The axial amount and the relationship between the axises of corneal astigmatism and total astigmatism were statistically analyzed in ametropic patients, for the purpose of selecting the refractive correction, the base curve of contact lens, the axis of astigmatic contact lens, and providing the reference of operational amount of ecimer laser keratoplasty. METHODS The refractive state and the corneal curvature of ametropic patients were measured and consecutvely repeated 3 times in the same eye at the same state with the same autorefractometer in 107 cases. The detected axises of total astigmatism and corneal astigmatism were statistically analyzed through the computerized recording. RESULTS The mean angle between the axis of corneal astigmatism and the axis of total astigmatism was 5.73 degrees +/- 3.97 degrees in myopic patients, 3.13 degrees +/- 2.49 degrees in mixture astigmatism patients and 6.35 degrees +/- 4.20 degrees in hyperopic patients. CONCLUSION The angle between the axis of corneal astigmatism and the axis of total astigmatism in the refractive state was mainly caused by the difference of the axises of surface astigmatism of lens and cornea.
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118
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Huang P, Zhu S, Lu S, Li L, Dai Z, Jin Y. [Cerulenin inhibits growth of human colonic carcinoma in nude mice]. ZHONGHUA BING LI XUE ZA ZHI = CHINESE JOURNAL OF PATHOLOGY 2000; 29:435-8. [PMID: 11866947] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/23/2023]
Abstract
OBJECTIVE To determine the effects of fatty acid synthase inhibitor, cerulenin, on tumor growth of human colonic carcinoma (LoVo) in nude mice. METHODS The transplantable colonic carcinoma cell line LoVo model was established in BALB/CA-nu/nu mice by subcutaneous implantation. Cerulenin was administrated by i.p. injection (80 mg/kg, 160 mg/kg each time) for 10 times. 17 days later the mice were killed and tumor size evaluated. RESULTS The size of tumors in cerulenin-treated group were significantly smaller than in control group and were similar to that of the 5-Fu treated group. Transmission electronic microscopy (TEM) revealed that death of LoVo cells treated by cerulenin was associated with apoptosis characterized by cell shrinkage, condensation and chromosome fragmentation. bcl-2 oncoprotein expression rate was significantly lower in cerulenin-treated group in comparing with the control group. The expression rate of bax was the opposite to that of bcl-2. CONCLUSIONS Cerulenin effectively suppresses the growth of human colonic carcinoma cells in vivo. The mechanism of cell death may be correlated with apoptosis, and bcl-2 and bax gene may play an important role in regulating cerulenin-induced apoptosis.
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Zou S, Qin R, Wang J, Yang C, Yi J, Qian J, Liu F, Qin X, Dai Z, Qiu F. [Prognostic factors of clinical curative effect for malignant obstructive jaundice]. ZHONGHUA WAI KE ZA ZHI [CHINESE JOURNAL OF SURGERY] 2000; 38:771-4. [PMID: 11832161] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/23/2023]
Abstract
OBJECTIVE To explore prognostic factors for clinical treatment of patients with malignant obstructive jaundice. METHODS 17 variables from 216 consecutive patients with malignant obstructive jaundice admitted from 1990 to 1997 were included for statistical analysis. RESULTS The overall mortality was 19.9% (43/216), and the morbidity 37.5% (81/216). The morbidity of radical operation was higher than that of palliative operation (P < 0.01). There was a highly significant correlation between mortality, morbidity, ASA grade and duration of jaundice (P < 0.01). No correlation was seen between the mortality, type of operation and cause of jaundice. There was a highly significant correlation between the morbidity and the type of operation. CONCLUSIONS The choice of operation in patients with malignant obstructive jaundice is radical operation. Early diagnosis and choice of treatment are essential to improving carative effect.
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Huang J, Liu E, Dai Z, Shen C, Yang S, Chen N, Huang J. [The molecular spectra and existence state of sulfonated phthalimidomethyl phthalocyanine hydroxyl aluminum as amphiphilic photosensitizer in aqueous alcoholic solutions and water]. GUANG PU XUE YU GUANG PU FEN XI = GUANG PU 2000; 20:673-676. [PMID: 12945414] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The sulfonated phthalimidomethyl phthalocyanine hydroxyl aluminum (Al(OH)PcSP) is an amphiphilic photosensitizer which was proved to have the photodynamic activities against cancer. The electronic absorption spectra and aggregation state of the Al(OH)PcSP in aqueous alcoholic solutions and water were investigated. The results showed that the Al(OH)PcSP existed in the form of monomer in aqueous alcoholic solutions. The increase in the carbon chain and hydroxy of alcohol in solutions had no significant effects on the absorption spectra behaviors of Al(OH)PcSP. But in water, the Al(OH)PcSP existed in the equilibrium between monomer and dimer. The dimerization constant was 5.7307 x 10(4) mol-1.L. The characteristic absorption peak of the Q band of the Al(OH)PcSP dimer was red shifted to 740.5 nm from that of the monomer (676.5 nm), which contrast with those of other metal phthalocyanines dimer. The study on the fluorescence spectra of Al(OH)PcSP in aqueous alcoholic solutions suggested that the fluorescence of the dimer was weak.
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Dai Z, Luo X, Xie H, Peng HB. The actin-driven movement and formation of acetylcholine receptor clusters. J Cell Biol 2000; 150:1321-34. [PMID: 10995438 PMCID: PMC2150690 DOI: 10.1083/jcb.150.6.1321] [Citation(s) in RCA: 109] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2000] [Accepted: 07/18/2000] [Indexed: 11/22/2022] Open
Abstract
A new method was devised to visualize actin polymerization induced by postsynaptic differentiation signals in cultured muscle cells. This entails masking myofibrillar filamentous (F)-actin with jasplakinolide, a cell-permeant F-actin-binding toxin, before synaptogenic stimulation, and then probing new actin assembly with fluorescent phalloidin. With this procedure, actin polymerization associated with newly induced acetylcholine receptor (AChR) clustering by heparin-binding growth-associated molecule-coated beads and by agrin was observed. The beads induced local F-actin assembly that colocalized with AChR clusters at bead-muscle contacts, whereas both the actin cytoskeleton and AChR clusters induced by bath agrin application were diffuse. By expressing a green fluorescent protein-coupled version of cortactin, a protein that binds to active F-actin, the dynamic nature of the actin cytoskeleton associated with new AChR clusters was revealed. In fact, the motive force generated by actin polymerization propelled the entire bead-induced AChR cluster with its attached bead to move in the plane of the membrane. In addition, actin polymerization is also necessary for the formation of both bead and agrin-induced AChR clusters as well as phosphotyrosine accumulation, as shown by their blockage by latrunculin A, a toxin that sequesters globular (G)-actin and prevents F-actin assembly. These results show that actin polymerization induced by synaptogenic signals is necessary for the movement and formation of AChR clusters and implicate a role of F-actin as a postsynaptic scaffold for the assembly of structural and signaling molecules in neuromuscular junction formation.
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Dai Z, Konieczny BT, Lakkis FG. The dual role of IL-2 in the generation and maintenance of CD8+ memory T cells. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2000; 165:3031-6. [PMID: 10975812 DOI: 10.4049/jimmunol.165.6.3031] [Citation(s) in RCA: 68] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The mechanisms responsible for the generation and maintenance of T cell memory are unclear. In this study, we tested the role of IL-2 in allospecific CD8+ T cell memory by analyzing the long-term survival, phenotype, and functional characteristics of IL-2-replete (IL-2+/+) and IL-2-deficient (IL-2-/-) CD8+ TCR-transgenic lymphocytes in an adoptive transfer model. We found that IL-2 is not essential for the in vivo generation, maintenance, or recall response of CD8+ memory T cells. However, IL-2 increased the size of the CD8+ memory pool if present at the time of initial T cell activation but reduced the size of the pool if present during memory maintenance by inhibiting the proliferation of CD8+ memory T cells. Thus, IL-2-based vaccine strategies or immunosuppressive regimens that target IL-2 should take into account the divergent roles of IL-2 in CD8+ T cell immunity.
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Dai Z, Kerzic P, Schroeder W, McNiece I. Mutant forms of bcr-abl deficient in inducing abi degradation show different leukemogenic activity. Exp Hematol 2000. [DOI: 10.1016/s0301-472x(00)00367-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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Wagener ME, Konieczny BT, Dai Z, Ring GH, Lakkis FG. Alloantigen-driven T cell death mediated by Fas ligand and tumor necrosis factor-alpha is not essential for the induction of allograft acceptance. Transplantation 2000; 69:2428-32. [PMID: 10868653 DOI: 10.1097/00007890-200006150-00037] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND Fas ligand (FasL)-Fas and tumor necrosis factor alpha (TNFalpha)-tumor necrosis factor receptor (TNFR) interactions regulate immune responses and contribute to self-tolerance by mediating antigen-driven T cell apoptosis. It is not known whether FasL and TNFalpha, expressed by the recipient's lymphoid or nonlymphoid cells, are essential for the apoptosis of alloreactive T lymphocytes and the induction of allograft acceptance. METHODS We compared the survival of fully allogeneic vascularized cardiac allografts between wild-type (wt) and FasL-mutant (gld) recipient mice. In addition, we studied cardiac allograft survival in gld mice injected with TNFalpha-neutralizing antibody. Allograft acceptance (graft survival >100 days) was induced by treating the recipients with CTLA4Ig, a recombinant fusion protein that blocks B7-CD28 T cell costimulation. In vivo alloantigen-driven apoptosis of mature CD4+ and CD8+ T lymphocytes was analyzed in mice repeatedly stimulated with allogeneic splenocytes. RESULTS We found that CTLA4Ig induces 100% long-term acceptance of cardiac allografts in wt and gld mice. Similarly, CTLA4Ig induced 100% allograft acceptance in gld recipients injected with TNFalpha-neutralizing antibody. In vivo alloantigen-driven apoptosis of mature CD4+ and CD8+ T cells was significantly reduced in gld mice and in wt mice treated with anti-TNFalpha antibody. However, neutralizing TNFalpha activity in gld mice failed to abrogate alloantigen-driven T cell apoptosis. CONCLUSIONS These data indicate that: (1) FasL and TNFalpha expression are not obligatory for the induction of long-term allograft acceptance by CTLA4Ig and (2) FasL- and TNFalpha-independent death pathways contribute to alloantigen-driven T cell apoptosis.
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Chen B, Huang P, Dai Z, Lin G. [Proliferation inhibition and apoptosis induction of K562 cells by fatty acid synthase inhibitor--cerulenin]. ZHONGHUA XUE YE XUE ZA ZHI = ZHONGHUA XUEYEXUE ZAZHI 2000; 21:244-6. [PMID: 11876988] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/24/2023]
Abstract
OBJECTIVE To investigate the effect of fatty acid synthase (FAS) inhibitor--cerulenin on K562 leukemia cells and its mechanism. METHODS Inhibition rate of cerulenin on K562 leukemia cells was assayed by MTT method, cell apoptosis by flow cytometry (FCM) and agarose gel electrophoresis. RESULTS When treated with 10(-9) - 10(-5) mol/L of cerulenin for 24 h, the proliferation of K562 cells was obviously inhibited with dose related effect. At the same concentrations, the inhibition rates of human skin fibroblasts were all lower than 30%. When K562 cells were treated for 12 h with 50 microg/ml and 60 microg/ml of cerulenin, the apoptosis rate revealed by FCM was 42.30% and 38.8%, respectively, and DNA agarose gel electrophoresis showed the typical DNA ladder of apoptosis. CONCLUSION Fatty acid synthase inhibitor--cerulenin inhibits proliferation of K562 cells but not of human fibroblasts. Cerulenin mediated cytotoxity is due to apoptosis induction. Fatty acid synthase might be a potential target for anti-leukemia.
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