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Lanis JM, Lewis MS, Strassburger H, Larsen K, Bagby SM, Dominguez ATA, Marín-Jiménez JA, Pelanda R, Pitts TM, Lang J. Testing Cancer Immunotherapeutics in a Humanized Mouse Model Bearing Human Tumors. J Vis Exp 2022. [PMID: 36591990 DOI: 10.3791/64606] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Reversing the immunosuppressive nature of the tumor microenvironment is critical for the successful treatment of cancers with immunotherapy drugs. Murine cancer models are extremely limited in their diversity and suffer from poor translation to the clinic. To serve as a more physiological preclinical model for immunotherapy studies, this protocol has been developed to evaluate the treatment of human tumors in a mouse reconstituted with a human immune system. This unique protocol demonstrates the development of human immune system (HIS, "humanized") mice, followed by implantation of a human tumor, either a cell-line derived xenograft (CDX) or a patient derived xenograft (PDX). HIS mice are generated by injecting CD34+ human hematopoietic stem cells isolated from umbilical cord blood into neonatal BRGS (BALB/c Rag2-/- IL2RγC-/- NODSIRPα) highly immunodeficient mice that are also capable of accepting a xenogeneic tumor. The importance of the kinetics and characteristics of the human immune system development and tumor implantation is emphasized. Finally, an in-depth evaluation of the tumor microenvironment using flow cytometry is described. In numerous studies using this protocol, it was found that the tumor microenvironment of individual tumors is recapitulated in HIS-PDX mice; "hot" tumors exhibit large immune infiltration while "cold" tumors do not. This model serves as a testing ground for combination immunotherapies for a wide range of human tumors and represents an important tool in the quest for personalized medicine.
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Affiliation(s)
- Jordi M Lanis
- Department of Immunology and Microbiology, School of Medicine, University of Colorado Denver Anschutz Medical Campus
| | - Matthew S Lewis
- Department of Immunology and Microbiology, School of Medicine, University of Colorado Denver Anschutz Medical Campus
| | - Hannah Strassburger
- Department of Immunology and Microbiology, School of Medicine, University of Colorado Denver Anschutz Medical Campus
| | - Kristina Larsen
- Department of Immunology and Microbiology, School of Medicine, University of Colorado Denver Anschutz Medical Campus
| | - Stacey M Bagby
- Division of Oncology, School of Medicine, University of Colorado Denver Anschutz Medical Campus
| | - Adrian T A Dominguez
- Division of Oncology, School of Medicine, University of Colorado Denver Anschutz Medical Campus
| | - Juan A Marín-Jiménez
- Department of Medical Oncology, Catalan Institute of Oncology (ICO-L'Hospitalet)
| | - Roberta Pelanda
- Department of Immunology and Microbiology, School of Medicine, University of Colorado Denver Anschutz Medical Campus
| | - Todd M Pitts
- Division of Oncology, School of Medicine, University of Colorado Denver Anschutz Medical Campus
| | - Julie Lang
- Department of Immunology and Microbiology, School of Medicine, University of Colorado Denver Anschutz Medical Campus;
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Lang J, Leal AD, Marín-Jiménez JA, Hartman SJ, Shulman J, Navarro NM, Lewis MS, Capasso A, Bagby SM, Yacob BW, MacBeth M, Freed BM, Eckhardt SG, Jordan K, Blatchford PJ, Pelanda R, Lieu CH, Messersmith WA, Pitts TM. Cabozantinib sensitizes microsatellite stable colorectal cancer to immune checkpoint blockade by immune modulation in human immune system mouse models. Front Oncol 2022; 12:877635. [PMID: 36419897 PMCID: PMC9676436 DOI: 10.3389/fonc.2022.877635] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2022] [Accepted: 10/17/2022] [Indexed: 12/23/2023] Open
Abstract
Immune checkpoint inhibitors have been found to be effective in metastatic MSI-high colorectal cancers (CRC), however, have no efficacy in microsatellite stable (MSS) cancers, which comprise the majority of mCRC cases. Cabozantinib is a small molecule multi-tyrosine kinase inhibitor that is FDA approved in advanced renal cell, medullary thyroid, and hepatocellular carcinoma. Using Human Immune System (HIS) mice, we tested the ability of cabozantinib to prime MSS-CRC tumors to enhance the potency of immune checkpoint inhibitor nivolumab. In four independent experiments, we implanted distinct MSS-CRC patient-derived xenografts (PDXs) into the flanks of humanized BALB/c-Rag2nullIl2rγnullSirpαNOD (BRGS) mice that had been engrafted with human hematopoietic stem cells at birth. For each PDX, HIS-mice cohorts were treated with vehicle, nivolumab, cabozantinib, or the combination. In three out of the four models, the combination had a lower tumor growth rate compared to vehicle or nivolumab-treated groups. Furthermore, interrogation of the HIS in immune organs and tumors by flow cytometry revealed increased Granzyme B+, TNFα+ and IFNγ+ CD4+ T cells among the human tumor infiltrating leukocytes (TIL) that correlated with reduced tumor growth in the combination-treated HIS-mice. Notably, slower growth correlated with increased expression of the CD4+ T cell ligand, HLA-DR, on the tumor cells themselves. Finally, the cabozantinib/nivolumab combination was tested in comparison to cobimetinib/atezolizumab. Although both combinations showed tumor growth inhibition, cabozantinib/nivolumab had enhanced cytotoxic IFNγ and TNFα+ T cells. This pre-clinical in vivo data warrants testing the combination in clinical trials for patients with MSS-CRC.
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Affiliation(s)
- Julie Lang
- Department of Immunology and Microbiology, University of Colorado Anschutz Medical Campus, Aurora, CO, United States
| | - Alexis D. Leal
- Division of Medical Oncology, Department of Medicine, University of Colorado School of Medicine, Aurora, CO, United States
| | - Juan A. Marín-Jiménez
- Department of Medical Oncology, Catalan Institute of Oncology (ICO-L´Hospitalet), Barcelona, Spain
| | - Sarah J. Hartman
- Division of Medical Oncology, Department of Medicine, University of Colorado School of Medicine, Aurora, CO, United States
| | - Jeremy Shulman
- Department of Immunology and Microbiology, University of Colorado Anschutz Medical Campus, Aurora, CO, United States
| | - Natalie M. Navarro
- Division of Medical Oncology, Department of Medicine, University of Colorado School of Medicine, Aurora, CO, United States
| | - Matthew S. Lewis
- Department of Immunology and Microbiology, University of Colorado Anschutz Medical Campus, Aurora, CO, United States
| | - Anna Capasso
- Department of Oncology, Livestrong Cancer Institutes, Dell Medical School, University of Texas at Austin, Austin, TX, United States
| | - Stacey M. Bagby
- Division of Medical Oncology, Department of Medicine, University of Colorado School of Medicine, Aurora, CO, United States
| | - Bethlehem W. Yacob
- Division of Medical Oncology, Department of Medicine, University of Colorado School of Medicine, Aurora, CO, United States
| | - Morgan MacBeth
- Division of Medical Oncology, Department of Medicine, University of Colorado School of Medicine, Aurora, CO, United States
| | - Brian M. Freed
- Division of Allergy and Clinical Immunology, School of Medicine, University of Colorado, Anschutz Medical Campus, Aurora, CO, United States
| | - S. Gail Eckhardt
- Department of Oncology, Livestrong Cancer Institutes, Dell Medical School, University of Texas at Austin, Austin, TX, United States
| | - Kimberly Jordan
- Department of Immunology and Microbiology, University of Colorado Anschutz Medical Campus, Aurora, CO, United States
| | - Patrick J. Blatchford
- Department of Biostatistics and Informatics, Colorado School of Public Health, University of Colorado Denver, Aurora, CO, United States
| | - Roberta Pelanda
- Department of Immunology and Microbiology, University of Colorado Anschutz Medical Campus, Aurora, CO, United States
| | - Christopher H. Lieu
- Division of Medical Oncology, Department of Medicine, University of Colorado School of Medicine, Aurora, CO, United States
| | - Wells A. Messersmith
- Division of Medical Oncology, Department of Medicine, University of Colorado School of Medicine, Aurora, CO, United States
| | - Todd M. Pitts
- Division of Medical Oncology, Department of Medicine, University of Colorado School of Medicine, Aurora, CO, United States
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Dominguez ATA, Real AG, Levandowski CB, Lewis MS, Hartman S, Yacob B, Smoots S, Schreiber A, Lanis J, Nepal P, Diamond J, Lieu C, Messersmith W, Lang J, Pitts T. Abstract 3509: Immune modulation in immune co-cultures of pancreatic ductal adenocarcinoma by small molecule CLK/WNT pathway inhibitor SM04690. Cancer Res 2022. [DOI: 10.1158/1538-7445.am2022-3509] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Abstract
Pancreatic ductal adenocarcinoma (PDAC) shows little to no symptoms and is often detected at later stages which makes it difficult to treat resulting in a very low survival rate. PDAC is resistant to most chemotherapy mostly due to a high amount of stroma and low vascularity. Additionally, PDAC is resistant to the newer immunotherapies due to the lack of immune cells and/or the presence of exhausted T-cells. Expression of WNT pathway genes allows cancer to avoid the immune system by affecting immune cell activation and migration into the tumor microenvironment. In this study, we investigate Immune activation and migration by co-culturing peripheral blood mononuclear cells (PBMCs) with PDAC spheroids in the presence of SM04690 (CLK/WNTi). SM04690 is a potent CLK and downstream WNT signaling inhibitor. The migration of PBMCs into PDAC spheroids were analyzed by FLOW cell cytometry and fluorescence confocal microscopy. The total CD3+ T cell population remained unchanged in the presence of SM04690, however, T cell subpopulations were affected by WNT inhibition. The total CD4+ T cell population in the spheroid co-culture was significantly increased while the CD8+ population was significantly reduced. Among the CD4+ T cell population, there was a significant increase in CCR7+CD45RA- central memory cells and CCR7-CD45RA- effector memory cells, while there was a significant decrease in FoxP3+CD25+ regulatory T cells. Surface expression of PD-L1 and HLA-DR on PDAC cells were also significantly increased compared to the untreated co-culture control. Fluorescent labeled PDAC and PBMCs allow clear quantification of immune infiltration through spheroid and Matrigel organoid systems. Genes associated with b-catenin destruction complex (AXIN1 and 2, APC, GSK3A) and transcription factors associated with gene expression (TCF7 and TCF7L1) were also significantly reduced in the drug treatment. Additional studies are ongoing investigating the role cancer-associated fibroblast (CAFs) play in the tumor microenvironment in the presence of SM04690 (CLK/WNTi). WNT inhibition can be a potent immune modulator and influence surface marker expression on the tumor. This can lead to future drug combinations with immune checkpoint inhibitors or drug combinations taking advantage of expression changes. Future directions involve utilizing PRO-seq to identify enhancer RNAs and immediate transcriptional effects of WNT inhibition, identify novel targets for combination therapy, and in vivo PDAC humanized animal models studying the effects in the presence of an autologous immune system.
Citation Format: Adrian TA Dominguez, Adreanna G. Real, Cecilia B. Levandowski, Matthew S. Lewis, Sarah Hartman, Betelehem Yacob, Stephen Smoots, Anna Schreiber, Jordi Lanis, Pragya Nepal, Jennifer Diamond, Chris Lieu, Wells Messersmith, Julie Lang, Todd Pitts. Immune modulation in immune co-cultures of pancreatic ductal adenocarcinoma by small molecule CLK/WNT pathway inhibitor SM04690 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 3509.
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Affiliation(s)
| | | | | | | | - Sarah Hartman
- 1University of Colorado Anschutz Medical Campus, Aurora, CO
| | | | - Stephen Smoots
- 1University of Colorado Anschutz Medical Campus, Aurora, CO
| | - Anna Schreiber
- 1University of Colorado Anschutz Medical Campus, Aurora, CO
| | - Jordi Lanis
- 1University of Colorado Anschutz Medical Campus, Aurora, CO
| | - Pragya Nepal
- 1University of Colorado Anschutz Medical Campus, Aurora, CO
| | | | - Chris Lieu
- 1University of Colorado Anschutz Medical Campus, Aurora, CO
| | | | - Julie Lang
- 1University of Colorado Anschutz Medical Campus, Aurora, CO
| | - Todd Pitts
- 1University of Colorado Anschutz Medical Campus, Aurora, CO
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Marín-Jiménez JA, Capasso A, Lewis MS, Bagby SM, Hartman SJ, Shulman J, Navarro NM, Yu H, Rivard CJ, Wang X, Barkow JC, Geng D, Kar A, Yingst A, Tufa DM, Dolan JT, Blatchford PJ, Freed BM, Torres RM, Davila E, Slansky JE, Pelanda R, Eckhardt SG, Messersmith WA, Diamond JR, Lieu CH, Verneris MR, Wang JH, Kiseljak-Vassiliades K, Pitts TM, Lang J. Testing Cancer Immunotherapy in a Human Immune System Mouse Model: Correlating Treatment Responses to Human Chimerism, Therapeutic Variables and Immune Cell Phenotypes. Front Immunol 2021; 12:607282. [PMID: 33854497 PMCID: PMC8040953 DOI: 10.3389/fimmu.2021.607282] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2020] [Accepted: 03/04/2021] [Indexed: 01/22/2023] Open
Abstract
Over the past decade, immunotherapies have revolutionized the treatment of cancer. Although the success of immunotherapy is remarkable, it is still limited to a subset of patients. More than 1500 clinical trials are currently ongoing with a goal of improving the efficacy of immunotherapy through co-administration of other agents. Preclinical, small-animal models are strongly desired to increase the pace of scientific discovery, while reducing the cost of combination drug testing in humans. Human immune system (HIS) mice are highly immune-deficient mouse recipients rtpeconstituted with human hematopoietic stem cells. These HIS-mice are capable of growing human tumor cell lines and patient-derived tumor xenografts. This model allows rapid testing of multiple, immune-related therapeutics for tumors originating from unique clinical samples. Using a cord blood-derived HIS-BALB/c-Rag2nullIl2rγnullSIRPαNOD (BRGS) mouse model, we summarize our experiments testing immune checkpoint blockade combinations in these mice bearing a variety of human tumors, including breast, colorectal, pancreatic, lung, adrenocortical, melanoma and hematological malignancies. We present in-depth characterization of the kinetics and subsets of the HIS in lymph and non-lymph organs and relate these to protocol development and immune-related treatment responses. Furthermore, we compare the phenotype of the HIS in lymph tissues and tumors. We show that the immunotype and amount of tumor infiltrating leukocytes are widely-variable and that this phenotype is tumor-dependent in the HIS-BRGS model. We further present flow cytometric analyses of immune cell subsets, activation state, cytokine production and inhibitory receptor expression in peripheral lymph organs and tumors. We show that responding tumors bear human infiltrating T cells with a more inflammatory signature compared to non-responding tumors, similar to reports of "responding" patients in human immunotherapy clinical trials. Collectively these data support the use of HIS mice as a preclinical model to test combination immunotherapies for human cancers, if careful attention is taken to both protocol details and data analysis.
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Affiliation(s)
- Juan A. Marín-Jiménez
- Department of Medical Oncology, Catalan Institute of Oncology (ICO-L’Hospitalet), Barcelona, Spain
| | - Anna Capasso
- Department of Oncology, Livestrong Cancer Institutes, Dell Medical School, University of Texas at Austin, Austin, TX, United States
| | - Matthew S. Lewis
- Department of Immunology and Microbiology, School of Medicine, University of Colorado, Aurora, CO, United States
| | - Stacey M. Bagby
- Division of Medical Oncology, School of Medicine, University of Colorado, Aurora, CO, United States
| | - Sarah J. Hartman
- Division of Medical Oncology, School of Medicine, University of Colorado, Aurora, CO, United States
| | - Jeremy Shulman
- Department of Immunology and Microbiology, School of Medicine, University of Colorado, Aurora, CO, United States
| | - Natalie M. Navarro
- Division of Medical Oncology, School of Medicine, University of Colorado, Aurora, CO, United States
| | - Hui Yu
- Division of Medical Oncology, School of Medicine, University of Colorado, Aurora, CO, United States
- University of Colorado Cancer Center, Aurora, CO, United States
| | - Chris J. Rivard
- Division of Medical Oncology, School of Medicine, University of Colorado, Aurora, CO, United States
- University of Colorado Cancer Center, Aurora, CO, United States
| | - Xiaoguang Wang
- Department of Immunology and Microbiology, School of Medicine, University of Colorado, Aurora, CO, United States
| | - Jessica C. Barkow
- Department of Immunology and Microbiology, School of Medicine, University of Colorado, Aurora, CO, United States
| | - Degui Geng
- Division of Medical Oncology, School of Medicine, University of Colorado, Aurora, CO, United States
| | - Adwitiya Kar
- Division of Endocrinology, School of Medicine, University of Colorado, Aurora, CO, United States
| | - Ashley Yingst
- Department of Pediatrics, School of Medicine, University of Colorado, Aurora, CO, United States
| | - Dejene M. Tufa
- Department of Pediatrics, School of Medicine, University of Colorado, Aurora, CO, United States
| | - James T. Dolan
- Rocky Vista College of Osteopathic Medicine – OMS3, Rocky Vista University, Parker, CO, United States
| | - Patrick J. Blatchford
- Department of Biostatistics and Informatics, Colorado School of Public Health, University of Colorado Denver, Aurora, CO, United States
| | - Brian M. Freed
- Department of Immunology and Microbiology, School of Medicine, University of Colorado, Aurora, CO, United States
- Division of Allergy and Clinical Immunology, School of Medicine, University of Colorado, Aurora, CO, United States
| | - Raul M. Torres
- Department of Immunology and Microbiology, School of Medicine, University of Colorado, Aurora, CO, United States
- University of Colorado Cancer Center, Aurora, CO, United States
| | - Eduardo Davila
- Division of Medical Oncology, School of Medicine, University of Colorado, Aurora, CO, United States
- University of Colorado Cancer Center, Aurora, CO, United States
| | - Jill E. Slansky
- Department of Immunology and Microbiology, School of Medicine, University of Colorado, Aurora, CO, United States
- University of Colorado Cancer Center, Aurora, CO, United States
| | - Roberta Pelanda
- Department of Immunology and Microbiology, School of Medicine, University of Colorado, Aurora, CO, United States
- University of Colorado Cancer Center, Aurora, CO, United States
| | - S. Gail Eckhardt
- Department of Oncology, Livestrong Cancer Institutes, Dell Medical School, University of Texas at Austin, Austin, TX, United States
| | - Wells A. Messersmith
- Division of Medical Oncology, School of Medicine, University of Colorado, Aurora, CO, United States
- University of Colorado Cancer Center, Aurora, CO, United States
| | - Jennifer R. Diamond
- Division of Medical Oncology, School of Medicine, University of Colorado, Aurora, CO, United States
- University of Colorado Cancer Center, Aurora, CO, United States
| | - Christopher H. Lieu
- Division of Medical Oncology, School of Medicine, University of Colorado, Aurora, CO, United States
| | - Michael R. Verneris
- Department of Pediatrics, School of Medicine, University of Colorado, Aurora, CO, United States
| | - Jing H. Wang
- Department of Immunology and Microbiology, School of Medicine, University of Colorado, Aurora, CO, United States
- University of Colorado Cancer Center, Aurora, CO, United States
| | - Katja Kiseljak-Vassiliades
- University of Colorado Cancer Center, Aurora, CO, United States
- Division of Endocrinology, School of Medicine, University of Colorado, Aurora, CO, United States
| | - Todd M. Pitts
- Division of Medical Oncology, School of Medicine, University of Colorado, Aurora, CO, United States
- University of Colorado Cancer Center, Aurora, CO, United States
| | - Julie Lang
- Department of Immunology and Microbiology, School of Medicine, University of Colorado, Aurora, CO, United States
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Lewis MS, Danelishvili L, Rose SJ, Bermudez LE. MAV_4644 Interaction with the Host Cathepsin Z Protects Mycobacterium avium subsp. hominissuis from Rapid Macrophage Killing. Microorganisms 2019; 7:microorganisms7050144. [PMID: 31117286 PMCID: PMC6560410 DOI: 10.3390/microorganisms7050144] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2019] [Revised: 05/03/2019] [Accepted: 05/10/2019] [Indexed: 01/15/2023] Open
Abstract
Mycobacterium avium subspecies hominissuis (MAH) is an opportunistic pathogen that is ubiquitous in the environment and often isolated from faucets and showerheads. MAH mostly infects humans with an underlying disease, such as chronic pulmonary disorder, cystic fibrosis, or individuals that are immunocompromised. In recent years, MAH infections in patients without concurrent disease are increasing in prevalence as well. This pathogen is resistant to many antibiotics due to the impermeability of its envelope and due to the phenotypic resistance established within the host macrophages, making difficult to treat MAH infections. By screening a MAH transposon library for mutants that are susceptible to killing by reactive nitrogen intermediaries, we identified the MAV_4644 (MAV_4644:Tn) gene knockout clone that was also significantly attenuated in growth within the host macrophages. Complementation of the mutant restored the wild-type phenotype. The MAV_4644 gene encodes a dual-function protein with a putative pore-forming function and ADP-ribosyltransferase activity. Protein binding assay suggests that MAV_4644 interacts with the host lysosomal peptidase cathepsin Z (CTSZ), a key regulator of the cell signaling and inflammation. Pathogenic mycobacteria have been shown to suppress the action of many cathepsins to establish their intracellular niche. Our results demonstrate that knocking-down the cathepsin Z in human macrophages rescues the attenuated phenotype of MAV_4644:Tn clone. Although, the purified cathepsin Z by itself does not have any killing effect on MAH, it contributes to bacterial killing in the presence of the nitric oxide (NO). Our data suggest that the cathepsin Z is involved in early macrophage killing of MAH, and the virulence factor MAV_4644 protects the pathogen from this process.
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Affiliation(s)
- Matthew S Lewis
- Department of Biomedical Sciences, College of Veterinary Medicine, Oregon State University, Corvallis, OR 97331, USA.
| | - Lia Danelishvili
- Department of Biomedical Sciences, College of Veterinary Medicine, Oregon State University, Corvallis, OR 97331, USA.
| | - Sasha J Rose
- Department of Biomedical Sciences, College of Veterinary Medicine, Oregon State University, Corvallis, OR 97331, USA.
| | - Luiz E Bermudez
- Department of Biomedical Sciences, College of Veterinary Medicine, Oregon State University, Corvallis, OR 97331, USA.
- Department of Microbiology, College of Science, Oregon State University, Corvallis, OR 97331, USA.
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Hansen SG, Piatak M, Ventura AB, Hughes CM, Gilbride RM, Ford JC, Oswald K, Shoemaker R, Li Y, Lewis MS, Gilliam AN, Xu G, Whizin N, Burwitz BJ, Planer SL, Turner JM, Legasse AW, Axthelm MK, Nelson JA, Früh K, Sacha JB, Estes JD, Keele BF, Edlefsen PT, Lifson JD, Picker LJ. Addendum: Immune clearance of highly pathogenic SIV infection. Nature 2017. [PMID: 28636599 DOI: 10.1038/nature22984] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
This corrects the article DOI: 10.1038/nature12519.
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Hansen SG, Piatak M, Ventura AB, Hughes CM, Gilbride RM, Ford JC, Oswald K, Shoemaker R, Li Y, Lewis MS, Gilliam AN, Xu G, Whizin N, Burwitz BJ, Planer SL, Turner JM, Legasse AW, Axthelm MK, Nelson JA, Früh K, Sacha JB, Estes JD, Keele BF, Edlefsen PT, Lifson JD, Picker LJ. Correction: Corrigendum: Immune clearance of highly pathogenic SIV infection. Nature 2014. [DOI: 10.1038/nature13840] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Malouli D, Hansen SG, Nakayasu ES, Marshall EE, Hughes CM, Ventura AB, Gilbride RM, Lewis MS, Xu G, Kreklywich C, Whizin N, Fischer M, Legasse AW, Viswanathan K, Siess D, Camp DG, Axthelm MK, Kahl C, DeFilippis VR, Smith RD, Streblow DN, Picker LJ, Früh K. Cytomegalovirus pp65 limits dissemination but is dispensable for persistence. J Clin Invest 2014; 124:1928-44. [PMID: 24691437 DOI: 10.1172/jci67420] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2012] [Accepted: 02/13/2014] [Indexed: 11/17/2022] Open
Abstract
The most abundantly produced virion protein in human cytomegalovirus (HCMV) is the immunodominant phosphoprotein 65 (pp65), which is frequently included in CMV vaccines. Although it is nonessential for in vitro CMV growth, pp65 displays immunomodulatory functions that support a potential role in primary and/or persistent infection. To determine the contribution of pp65 to CMV infection and immunity, we generated a rhesus CMV lacking both pp65 orthologs (RhCMVΔpp65ab). While deletion of pp65ab slightly reduced growth in vitro and increased defective particle formation, the protein composition of secreted virions was largely unchanged. Interestingly, pp65 was not required for primary and persistent infection in animals. Immune responses induced by RhCMVΔpp65ab did not prevent reinfection with rhesus CMV; however, reinfection with RhCMVΔUS2-11, which lacks viral-encoded MHC-I antigen presentation inhibitors, was prevented. Unexpectedly, induction of pp65b-specific T cells alone did not protect against RhCMVΔUS2-11 challenge, suggesting that T cells targeting multiple CMV antigens are required for protection. However, pp65-specific immunity was crucial for controlling viral dissemination during primary infection, as indicated by the marked increase of RhCMVΔpp65ab genome copies in CMV-naive, but not CMV-immune, animals. Our data provide rationale for inclusion of pp65 into CMV vaccines but also demonstrate that pp65-induced T cell responses alone do not recapitulate the protective effect of natural infection.
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Hansen SG, Sacha JB, Hughes CM, Ford JC, Burwitz BJ, Scholz I, Gilbride RM, Lewis MS, Gilliam AN, Ventura AB, Malouli D, Xu G, Richards R, Whizin N, Reed JS, Hammond KB, Fischer M, Turner JM, Legasse AW, Axthelm MK, Edlefsen PT, Nelson JA, Lifson JD, Früh K, Picker LJ. Cytomegalovirus vectors violate CD8+ T cell epitope recognition paradigms. Science 2013; 340:1237874. [PMID: 23704576 DOI: 10.1126/science.1237874] [Citation(s) in RCA: 351] [Impact Index Per Article: 31.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
CD8(+) T cell responses focus on a small fraction of pathogen- or vaccine-encoded peptides, and for some pathogens, these restricted recognition hierarchies limit the effectiveness of antipathogen immunity. We found that simian immunodeficiency virus (SIV) protein-expressing rhesus cytomegalovirus (RhCMV) vectors elicit SIV-specific CD8(+) T cells that recognize unusual, diverse, and highly promiscuous epitopes, including dominant responses to epitopes restricted by class II major histocompatibility complex (MHC) molecules. Induction of canonical SIV epitope-specific CD8(+) T cell responses is suppressed by the RhCMV-encoded Rh189 gene (corresponding to human CMV US11), and the promiscuous MHC class I- and class II-restricted CD8(+) T cell responses occur only in the absence of the Rh157.5, Rh157.4, and Rh157.6 (human CMV UL128, UL130, and UL131) genes. Thus, CMV vectors can be genetically programmed to achieve distinct patterns of CD8(+) T cell epitope recognition.
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Affiliation(s)
- Scott G Hansen
- Vaccine and Gene Therapy Institute and Oregon National Primate Research Center, Oregon Health & Science University, Beaverton, OR 97006, USA
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Affiliation(s)
| | | | - Nicole Berkhout
- Menzies School of Health Research, Darwin, Northern Territory
| | - Susan Sayers
- Menzies School of Health Research, Darwin, Northern Territory
| | - Paul Maruff
- Centre for Neuroscience, University of Melbourne
- CogState, Melbourne, Victoria, Australia
| | - Sheree Cairney
- Menzies School of Health Research, Darwin, Northern Territory
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Affiliation(s)
- Kylie M. Dingwall
- Menzies School of Health Research, Institute of Advanced Studies, Charles Darwin University, Darwin, Northern Territory
| | - Matthew S. Lewis
- Menzies School of Health Research, Institute of Advanced Studies, Charles Darwin University, Darwin, Northern Territory
| | - Paul Maruff
- Centre for Neuroscience, University of Melbourne
- CogState, Melbourne, Victoria, Australia
| | - Sheree Cairney
- Menzies School of Health Research, Institute of Advanced Studies, Charles Darwin University, Darwin, Northern Territory
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Silbert BS, Scott DA, Evered LA, Lewis MS, Maruff PT. Preexisting Cognitive Impairment in Patients Scheduled for Elective Coronary Artery Bypass Graft Surgery. Anesth Analg 2007; 104:1023-8, tables of contents. [PMID: 17456647 DOI: 10.1213/01.ane.0000263285.03361.3a] [Citation(s) in RCA: 89] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
BACKGROUND An accurate assessment of the prevalence of cognitive impairment in patients scheduled for coronary artery bypass graft (CABG) surgery is necessary if valid assumptions regarding cognitive change are to be made. Such an assessment requires the use of a healthy control group free of cardiovascular disease. METHODS In a retrospective observational study, 349 patients scheduled for CABG surgery underwent neuropsychological testing. We compared the results with those from a group of 170 healthy controls without cardiovascular disease and containing more female patients who were matched for age and IQ score. Cognitive impairment was defined as test scores > or =2 sd less than the controls on two or more of the seven tests. RESULTS The CABG surgery patients performed significantly worse than the control group on all tests except the Grooved Pegboard test (nondominant). When analyzed by group, performance on the verbal learning test was the most impaired. Cognitive impairment was present in 122 (35%) of CABG surgery patients before their procedure. Prior myocardial infarction, age, and IQ were independent predictors of cognitive impairment. CONCLUSIONS Cognitive impairment is prevalent in patients presenting for CABG surgery. Impaired cognition before surgery must be considered when assessing the effects of CABG surgery on cognitive performance.
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Affiliation(s)
- Brendan S Silbert
- Department of Anaesthesia, Centre for Anaesthesia and Cognitive Function, St. Vincent's Hospital, Melbourne, Australia.
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13
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Lewis MS, Maruff P, Silbert BS, Evered LA, Scott DA. The influence of different error estimates in the detection of postoperative cognitive dysfunction using reliable change indices with correction for practice effects. Arch Clin Neuropsychol 2007; 22:249-57. [PMID: 17443923 DOI: 10.1016/j.acn.2007.01.019] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
Abstract
The reliable change index (RCI) expresses change relative to its associated error, and is useful in the identification of postoperative cognitive dysfunction (POCD). This paper examines four common RCIs that each account for error in different ways. Three rules incorporate a constant correction for practice effects and are contrasted with the standard RCI that had no correction for practice. These rules are applied to 160 patients undergoing coronary artery bypass graft (CABG) surgery who completed neuropsychological assessments preoperatively and 1 week postoperatively using error and reliability data from a comparable healthy nonsurgical control group. The rules all identify POCD in a similar proportion of patients, but the use of the within-subject standard deviation (WSD), expressing the effects of random error, as an error estimate is a theoretically appropriate denominator when a constant error correction, removing the effects of systematic error, is deducted from the numerator in a RCI.
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Affiliation(s)
- Matthew S Lewis
- Centre for Anaesthesia and Cognitive Function, Department of Anaesthesia, St. Vincent's Hospital, Victoria Parade, Melbourne 3065, Australia.
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14
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Lewis MS, Maruff P, Silbert BS, Evered LA, Scott DA. The influence of different error estimates in the detection of post-operative cognitive dysfunction using reliable change indices with correction for practice effects. Arch Clin Neuropsychol 2006; 21:421-7. [PMID: 16859888 DOI: 10.1016/j.acn.2006.05.004] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2005] [Revised: 05/05/2006] [Accepted: 05/12/2006] [Indexed: 11/29/2022] Open
Abstract
The reliable change index (RCI) expresses change relative to its associated error, and is useful in the identification of post-operative cognitive dysfunction (POCD). This paper examines four common RCIs that each account for error in different ways. Three rules incorporate a constant correction for practice effects and are contrasted with the standard RCI that had no correction for practice. These rules are applied to 160 patients undergoing coronary artery bypass graft (CABG) surgery who completed neuropsychological assessments preoperatively and 1 week post-operatively using error and reliability data from a comparable healthy non-surgical control group. The rules all identify POCD in a similar proportion of patients, but the use of the within subject standard deviation, expressing the effects of random error, as an error estimate is a theoretically appropriate denominator when a constant error correction, removing the effects of systematic error, is deducted from the numerator in a RCI.
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Affiliation(s)
- Matthew S Lewis
- Centre for Anaesthesia and Cognitive Function, Department of Anaesthesia, St. Vincent's Hospital, Victoria Parade, Melbourne 3065, Australia.
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15
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Silbert BS, Scott DA, Evered LA, Lewis MS, Kalpokas M, Maruff P, Myles PS, Jamrozik K. A comparison of the effect of high- and low-dose fentanyl on the incidence of postoperative cognitive dysfunction after coronary artery bypass surgery in the elderly. Anesthesiology 2006; 104:1137-45. [PMID: 16732083 DOI: 10.1097/00000542-200606000-00007] [Citation(s) in RCA: 76] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
BACKGROUND Postoperative cognitive dysfunction (POCD) after coronary artery bypass graft surgery is a common complication for which, despite many clinical investigations, no definitive etiology has been found. The current use of both high- and low-dose fentanyl as anesthetic techniques allowed us to investigate the effect of fentanyl on the incidence of POCD. METHODS Three hundred fifty patients scheduled to undergo elective coronary artery bypass graft surgery were randomized to receive either high-dose fentanyl (50 microg/kg) or low-dose fentanyl (10 mug/kg) as the basis of the anesthetic. All patients underwent neuropsychological testing before surgery and at 1 week, 3 months, and 12 months after surgery. RESULTS One hundred sixty-eight patients in the low-dose group and 158 patients in the high-dose group were included in the final analysis. Neuropsychological testing was performed on 88%, 93%, and 92% of patients at 1 week, 3 months, and 12 months, respectively. There was no difference between group mean scores at any of the three testing times. Analysis of individual patients by the 20% rule did not detect any differences between groups. The one SD rule, which has fewer false-positive results, detected significantly more patients with POCD in the low-dose group than in the high-dose group at 1 week (23.6% vs. 13.7%; P = 0.03) but not at the other testing times. Patients with POCD spent an average of 1.2 days longer in the hospital than those without POCD (P = 0.021). CONCLUSIONS High-dose fentanyl is not associated with a difference in the incidence of POCD at 3 or 12 months after surgery. Low-dose fentanyl leads to shorter postoperative ventilation times and may be associated with a greater incidence of POCD 1 week after surgery. Early POCD is associated with an increased duration of stay in the hospital.
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Affiliation(s)
- Brendan S Silbert
- Department of Anaesthesia, St. Vincent's Hospital, Melbourne, Australia.
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16
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Lewis MS, Maruff P, Silbert BS, Evered LA, Scott DA. Detection of Postoperative Cognitive Decline After Coronary Artery Bypass Graft Surgery is Affected by the Number of Neuropsychological Tests in the Assessment Battery. Ann Thorac Surg 2006; 81:2097-104. [PMID: 16731137 DOI: 10.1016/j.athoracsur.2006.01.044] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/17/2005] [Revised: 01/07/2006] [Accepted: 01/10/2006] [Indexed: 11/16/2022]
Abstract
BACKGROUND The assessment of postoperative cognitive dysfunction after coronary artery bypass graft surgery is made with the repeated administration of cognitive tests. This classification is vulnerable to error, and it has been suggested that increasing the number of tests in a battery while maintaining constant inclusion criteria for postoperative cognitive dysfunction increases the rate of false positive classification of deterioration. The current study tested this by applying a constant rule for cognitive dysfunction using combinations of two to seven cognitive tests. METHODS Two hundred and four coronary artery bypass graft patients (surgical) and 90 healthy nonsurgical controls aged 55 years or older completed a battery of cognitive tests at baseline (preoperative) and 1 week later (postoperative). In both groups, postoperative cognitive dysfunction was classified using all unique combinations of two to seven cognitive tests when performance deteriorated on two or more tests by at least the value of the baseline standard deviation. RESULTS The average incidence of cognitive dysfunction progressively increased in both groups as the number of cognitive tests increased from two (surgical: 13.3%; control: 3.1%) to seven tests (surgical: 49.4%; control: 41.1%). CONCLUSIONS Increasing the number of tests used to classify postoperative cognitive dysfunction appears to increase the sensitivity to change in the coronary artery bypass graft group. However, accompanying false positive classifications suggest that this improved sensitivity reflected increased error. Future rules for postoperative cognitive dysfunction need to account for this error and include a control group.
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Affiliation(s)
- Matthew S Lewis
- Centre for Anaesthesia and Cognitive Function, Department of Anaesthesia, St. Vincent's Hospital, Victoria Parade, Melbourne, Australia.
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17
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Abstract
The association between caregiver cognitive status and potentially harmful caregiver behavior was assessed in a sample of 180 caregiver-care recipient dyads. Compromised cognitive status was identified in 39% of these informal caregivers. Beyond variance explained by demographic factors, amount of care provided, care recipient cognitive status, and caregiver depressed affect, care recipients reported more frequently being subjected to potentially harmful caregiver behavior when their caregivers evidenced compromised cognitive status. While preliminary, critical areas of caregiver cognition appeared to be deficits in language comprehension and memory. Results indicate that compromised cognitive status is common among informal caregivers of impaired elders and that this may adversely influence the quality of care they provide.
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Affiliation(s)
- L S Miller
- Department of Psychology, University of Georgia, Athens, GA 30602-3013, USA.
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Lewis MS, Maruff P, Silbert BS, Evered LA, Scott DA. The sensitivity and specificity of three common statistical rules for the classification of post-operative cognitive dysfunction following coronary artery bypass graft surgery. Acta Anaesthesiol Scand 2006; 50:50-7. [PMID: 16451151 DOI: 10.1111/j.1399-6576.2006.00893.x] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
BACKGROUND The application of statistical rules to determine post-operative cognitive dysfunction (POCD) has varied, and partially explains the wide range of reported incidences of POCD in the literature. The current study assessed the sensitivity and specificity of three commonly used statistical rules in a sample of coronary artery bypass graft (CABG) patients and healthy non-surgical controls. METHODS Two hundred and four CABG patients [mean age, 68.8 years; standard deviation (SD), 7.0 years] completed neuropsychological assessment pre-operatively (baseline) and 1 week and 3 months post-operatively. Ninety age- and gender-matched non-surgical controls (mean age, 67.8 years; SD, 7.9 years) completed the same tasks at the same time points. POCD was determined in each group using three rules: the 1SD decline on two or more tasks; the 20% decline on 20% of tasks rule; and a modified reliable change index. RESULTS The modified reliable change index demonstrated the greatest combination of sensitivity and specificity. The 20% decline on 20% of tasks rule detected the largest incidence of impairment in the CABG group, but showed large incidences of false positive classifications in the control group. The 1SD rule detected the lowest incidence of POCD in the CABG group, but detected a larger incidence of impairment in the control group. CONCLUSIONS The use of the modified reliable change index is recommended, given the sensitivity to change it displayed and the low rates of false positive classification in the control sample. The use of control groups in future research is also recommended.
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Affiliation(s)
- M S Lewis
- Centre for Anaesthesia and Cognitive Function, Department of Anaesthesia, St. Vincent's Hospital, and School of Psychological Science, La Trobe University, Melbourne, Vic., Australia.
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19
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Lewis MS, Maruff PT, Silbert BS. Examination of the Use of Cognitive Domains in Postoperative Cognitive Dysfunction After Coronary Artery Bypass Graft Surgery. Ann Thorac Surg 2005; 80:910-6. [PMID: 16122453 DOI: 10.1016/j.athoracsur.2005.03.098] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/30/2004] [Revised: 03/22/2005] [Accepted: 03/23/2005] [Indexed: 10/25/2022]
Abstract
BACKGROUND Cognitive domain summary scores have been used to examine postoperative cognitive dysfunction in a number of influential studies. To successfully examine cognitive dysfunction in this way, the domains need to be consistent during the assessment time points or the results are distorted. The current study examines two methods of determining cognitive domains and examines their temporal stability during serial cognitive assessments after coronary artery bypass graft surgery. METHODS Two hundred and four coronary artery bypass graft patients and 80 matched healthy control subjects 55 years or older completed a battery of neuropsychological assessments at baseline and at 7 days and 3 months. Domains were determined in two ways. The first was based on precedence, and neuropsychological tests were allocated to commonly attributed cognitive domains. The second method was to conduct principal components analysis to statistically determine the domains at each time. The stability of these factors was then assessed over time by conducting repeated analysis. RESULTS There were discrepancies between the two methods used to determine decline, and among the factors in the control and surgical groups. Stability with time was not evident as the factors varied within the groups. CONCLUSIONS The assessment of postoperative cognitive dysfunction would be best served by the use of individual test results with efforts made to minimize false-positive classification as the extracted cognitive domains do not appear to be temporally consistent, and were sample specific.
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Affiliation(s)
- Matthew S Lewis
- Centre for Anaesthesia and Cognitive Function, Department of Anaesthesia, St. Vincent's Hospital, Victoria Parade, Australia.
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20
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Abstract
We report here a new DNA detection method in which polymer growth in atom transfer radical polymerization (ATRP) is used as a means to amplify detection signals. In this method, DNA hybridization and ligation reactions led to the attachment of ATRP initiators on a solid surface where specific DNA sequences were located. These initiators subsequently triggered the growth of poly(hydroxyethyl methacrylate) (PHEMA) at the end of immobilized DNA molecules and formed polymer brushes. The formation of PHEMA altered substrate opacity, rendering the corresponding spots readily distinguishable to the naked eye. A second ATRP reaction to form branched polymers on the surface drastically improved the visibility of DNA hybridization and significantly shortened the detection time. The resulting polymer film was characterized using infrared spectroscopy, ellipsometry, contact angle measurements, and atomic force microscopy. Direct visualization of 1 fmol of target DNA molecules of interest was demonstrated. A proof-of-principle experiment to detect DNA point mutation was conducted. The perfectly matched DNA targets were distinctively differentiated from those with mutations. The demonstrated capability to detect DNA mutation with direct visualization laid the groundwork for the future development of detector-free testing kits in single-nucleotide polymorphism screenings.
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Affiliation(s)
- Xinhui Lou
- Department of Chemistry, North Carolina State University, Raleigh, North Carolina 27695, USA
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21
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Silbert BS, Maruff P, Evered LA, Scott DA, Kalpokas M, Martin KJ, Lewis MS, Myles PS. Detection of cognitive decline after coronary surgery: a comparison of computerized and conventional tests. Br J Anaesth 2004; 92:814-20. [PMID: 15064253 DOI: 10.1093/bja/aeh157] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
BACKGROUND Postoperative cognitive decline is a common complication after coronary artery bypass graft (CABG) surgery. Postoperative cognitive decline is defined on the basis of change in cognitive function detected with repeated assessments using neuropsychological tests. Therefore improvement in neuropsychological testing instruments may increase our understanding of postoperative cognitive decline. METHODS Fifty patients undergoing CABG surgery completed both a conventional and a computerized battery of tests before and 6 days after CABG surgery. Fifty age- and education-matched controls completed the same test batteries 6 days apart. The reliability and the sensitivity to postoperative cognitive decline were computed for each battery. RESULTS Both test batteries detected postoperative cognitive decline 6 days after CABG surgery. For the computerized battery, the reliability of the reaction times (intraclass correlation 0.89-0.92) was greater than for any test from the conventional battery (intraclass correlation 0.56-0.71), although accuracy measures were less reliable (intraclass correlation 0.61-0.89). The computerized battery detected all the cases of POCD identified by the conventional test battery and also five cases that were classified as normal by the conventional tests. CONCLUSION Computerized tests are suitable for measuring cognitive change after CABG surgery and may detect change in a greater proportion of patients 6 days after CABG surgery than conventional neuropsychological tests.
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Affiliation(s)
- B S Silbert
- Department of Anaesthesia, St Vincent's Hospital, Melbourne, Australia.
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22
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Lewis MS, Gorman CB. Scanning Tunneling Microscope-Based Replacement Lithography on Self-Assembled Monolayers. Investigation of the Relationship between Monolayer Structure and Replacement Bias. J Phys Chem B 2004. [DOI: 10.1021/jp0379244] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Matthew S. Lewis
- Department of Chemistry, North Carolina State University, Box 8204, Raleigh, North Carolina 27695-8204
| | - Christopher B. Gorman
- Department of Chemistry, North Carolina State University, Box 8204, Raleigh, North Carolina 27695-8204
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Mead GM, Sydes MR, Walewski J, Grigg A, Hatton CS, Pescosta N, Guarnaccia C, Lewis MS, McKendrick J, Stenning SP, Wright D, Norbert P. An international evaluation of CODOX-M and CODOX-M alternating with IVAC in adult Burkitt's lymphoma: results of United Kingdom Lymphoma Group LY06 study. Ann Oncol 2002; 13:1264-74. [PMID: 12181251 DOI: 10.1093/annonc/mdf253] [Citation(s) in RCA: 246] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
BACKGROUND Burkitt's lymphoma (BL) is a rare and rapidly progressive form of B-cell non-Hodgkin's lymphoma. Cyclophosphamide, vincristine, doxorubicin, high-dose methotrexate (CODOX-M)/ifosfamide, etoposide and high-dose cytarabine (IVAC) is a highly effective alternating non-cross-resistant regimen developed by Magrath et al. (Magrath I., Adde M., Shad A. et al. J Clin Oncol 1996; 14: 925-934) at the US National Cancer Institute. The aim was to confirm these results in a larger, international, multi-centre study using International Prognostic Index-based criteria to assign prognostic groups, whilst slightly simplifying the protocol. PATIENTS AND METHODS A phase II study where: (i) low risk (LR) patients were treated with three cycles of modified CODOX-M; and (ii) high risk (HR) patients received treatment with four cycles of alternating modified CODOX-M and IVAC chemotherapy. Target of 60 patients, fit for protocol treatment, from 16 to 60 years of age with locally diagnosed, non-HIV-related, non-organ-transplant-related BL. RESULTS Results are given for 52 of 72 registered patients whose pathological eligibility was confirmed by central pathology review: 12 LR plus 40 HR. The majority of patients (n = 41) completed protocol treatment, but toxicity was severe, especially myelosuppression and mucositis. Overall, 2-year event-free survival (EFS) was 64.6% (95% CI 50.4% to 78.9%) and 2-year overall survival (OS) was 72.8% (95% CI 59.4% to 86.3%). For LR, 2-year EFS was 83.3% and OS was 81.5%. For HR, 2-year EFS was 59.5% and OS was 69.9%. CONCLUSIONS This study confirms high cure rates with this CODOX-M/IVAC approach.
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Affiliation(s)
- G M Mead
- Wessex Medical Oncology Unit, Royal South Hants Hospital, Southampton, UK
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24
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Abstract
Failure of one parent's chromosomes to organize nucleoli in an interspecific hybrid is an epigenetic phenomenon known as nucleolar dominance. Selective gene silencing on a scale of millions of bp is known to be involved, but the full extent to which nucleolus organizer region (NOR)-bearing chromosomes are inactivated beyond the NORs is unknown. Aided by genome sequence data for Arabidopsis thaliana, we have mapped the extent of nucleolar dominance-induced silencing in Arabidopsis suecica, the allotetraploid hybrid of A. thaliana and Arabidopsis arenosa. Using a sensitive reverse transcription PCR assay, we show that the four A. thaliana NORs, each approximately 4 Mbp in size, are approximately 99.5% silenced in A. suecica vegetative leaves, whereas the NORs inherited from A. arenosa remain fully active. The two A. thaliana NORs, NOR2 and NOR4, abut the telomeres on chromosomes 2 and 4, thus there are no genes distal to the NORs. The three protein-coding genes nearest NOR4 on its centromere-proximal side, the closest of which is only 3.1 kb from rRNA gene sequences, are shown to be transcribed in the hybrid despite the silencing of the adjacent approximately 4-Mbp NOR. These data argue against hypotheses in which NOR inactivation is attributed to the spread of silencing from adjacent chromosomal regions, but favor models in which NORs or rRNA genes are the targets of regulation.
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Affiliation(s)
- M S Lewis
- Biology Department, Washington University, Campus Box 1137, One Brookings Drive, St. Louis, MO 63130, USA
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25
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Lee SP, Fuior E, Lewis MS, Han MK. Analytical ultracentrifugation studies of translin: analysis of protein-DNA interactions using a single-stranded fluorogenic oligonucleotide. Biochemistry 2001; 40:14081-8. [PMID: 11705401 DOI: 10.1021/bi010302t] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Translin is a recently identified nucleic acid binding protein that appears to be involved in the recognition of conserved sequences found at many chromosomal breakpoints. Previous reports indicate that, based on gel filtration analysis and electron microscopy of protein-DNA complexes, translin forms an octameric structure that binds the DNA. In this study, we further examine the possibility of self-association of translin and its interactions with DNA by analytical ultracentrifugation. Sedimentation velocity analysis of translin indicates that the predominant species sediments with a sedimentation coefficient of 8.5 S and has a frictional ratio, f/f(omicron), of 1.35; these data are consistent with the presence of an octamer with an ellipsoidal configuration; a small amount of a component with significantly higher mass is also present. Equilibrium sedimentation studies of translin at three different protein concentrations also indicate that the predominant species present is an octamer with a minor fraction of aggregated species. Neither monomer nor dimer was detected. Sedimentation equilibrium studies of translin with an FITC-labeled single-stranded oligonucleotide were performed to examine the interaction. A novel analysis method has been developed to analyze protein-nucleic acid interactions based on global fitting of scans of 280 and 490 nm to appropriate mathematical models. Utilizing this method, it was determined that the DNA binding species of translin is an octamer binding a single-stranded oligonucleotide with a DeltaG degrees value of -9.49 +/- 0.12 kcal/mol, corresponding to a dissociation constant, K(d), of 84 +/- 17 nM. On the basis of this evidence and electron microscopy, it is envisioned that translin forms an annular structure of eight subunits, hydrodynamically an oblate ellipsoid, which binds DNA at chromosomal breakpoints.
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Affiliation(s)
- S P Lee
- Department of Microbiology and Immunology, Georgetown University Medical Center, Washington, DC 20007, USA
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26
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Hebert AM, Strohmaier J, Whitman MC, Chen T, Gubina E, Hill DM, Lewis MS, Kozlowski S. Kinetics and thermodynamics of beta 2-microglobulin binding to the alpha 3 domain of major histocompatibility complex class I heavy chain. Biochemistry 2001; 40:5233-42. [PMID: 11318646 DOI: 10.1021/bi002392s] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The major histocompatibility complex (MHC) class I molecule plays a crucial role in cytotoxic lymphocyte function. Functional class I MHC exists as a heterotrimer consisting of the MHC class I heavy chain, an antigenic peptide fragment, and beta2-microglobulin (beta2m). beta2m has been previously shown to play an important role in the folding of the MHC heavy chain without continued beta2m association with the MHC complex. Therefore, beta2m is both a structural component of the MHC complex and a chaperone-like molecule for MHC folding. In this study we provide data supporting a model in which the chaperone-like role of beta2m is dependent on initial binding to only one of the two beta2m interfaces with class 1 heavy chain. beta2-Microglobulin binding to an isolated alpha3 domain of the class I MHC heavy chain accurately models the biochemistry and thermodynamics of beta2m-driven refolding. Our results explain a 1000-fold discrepancy between beta2m binding and refolding of MHC1. The biochemical study of the individual domains of complex molecules is an important strategy for understanding their dynamic structure and multiple functions.
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Affiliation(s)
- A M Hebert
- Division of Monoclonal Ab, Center for Biologics Evaluation and Research, Food and Drug Administration, Bethesda, Maryland 20892, USA
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27
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Affiliation(s)
- E K Dimitriadis
- Division of Bioengineering and Physical Science, ORS, OD, National Institute of Health, Bethesda, Maryland 20892-5766, USA
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28
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Affiliation(s)
- M S Lewis
- Division of Bioengineering and Physical Science, National Institutes of Health, Bethesda, Maryland 20892-5766, USA
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29
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Munro R, Dorward N, Lewis MS, Beddall A. Prothrombin time inhibition detected with recombinant but not with conventional thromboplastins in two patients with high-titre IgM and moderate-titre IgA anticardiolipin antibodies. Clin Lab Haematol 2001; 23:61-4. [PMID: 11422233 DOI: 10.1046/j.1365-2257.2001.00342.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
We report two cases of high-titre IgM and moderate-titre IgA anticardiolipin antibodies (ACA) in whom prothrombin times (PT) derived using recombinant thromboplastins (rTP) were prolonged but were normal when measured with conventional thromboplastins. The anticoagulant nature of these antibodies cannot be categorized as the classical lupus type. We suggest that routine screening for the presence of antiphospholipid antibodies (APA) should be performed in patients who fall into this category.
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Affiliation(s)
- R Munro
- Department of Haematology, Morriston Hospital, Swansea, UK.
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30
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Shcherbakova PV, Hall MC, Lewis MS, Bennett SE, Martin KJ, Bushel PR, Afshari CA, Kunkel TA. Inactivation of DNA mismatch repair by increased expression of yeast MLH1. Mol Cell Biol 2001; 21:940-51. [PMID: 11154280 PMCID: PMC86684 DOI: 10.1128/mcb.21.3.940-951.2001] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Inactivation of DNA mismatch repair by mutation or by transcriptional silencing of the MLH1 gene results in genome instability and cancer predisposition. We recently found (P. V. Shcherbakova and T. A. Kunkel, Mol. Cell. Biol. 19:3177-3183, 1999) that an elevated spontaneous mutation rate can also result from increased expression of yeast MLH1. Here we investigate the mechanism of this mutator effect. Hybridization of poly(A)(+) mRNA to DNA microarrays containing 96.4% of yeast open reading frames revealed that MLH1 overexpression did not induce changes in expression of other genes involved in DNA replication or repair. MLH1 overexpression strongly enhanced spontaneous mutagenesis in yeast strains with defects in the 3'-->5' exonuclease activity of replicative DNA polymerases delta and epsilon but did not enhance the mutation rate in strains with deletions of MSH2, MLH1, or PMS1. This suggests that overexpression of MLH1 inactivates mismatch repair of replication errors. Overexpression of the PMS1 gene alone caused a moderate increase in the mutation rate and strongly suppressed the mutator effect caused by MLH1 overexpression. The mutator effect was also reduced by a missense mutation in the MLH1 gene that disrupted Mlh1p-Pms1p interaction. Analytical ultracentrifugation experiments showed that purified Mlh1p forms a homodimer in solution, albeit with a K(d) of 3.14 microM, 36-fold higher than that for Mlh1p-Pms1p heterodimerization. These observations suggest that the mismatch repair defect in cells overexpressing MLH1 results from an imbalance in the levels of Mlh1p and Pms1p and that this imbalance might lead to formation of nonfunctional mismatch repair complexes containing Mlh1p homodimers.
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Affiliation(s)
- P V Shcherbakova
- Laboratories of Molecular Genetics, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina 27709, USA
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Bamford EJ, Bowen RH, Broad JP, Hawken A, Morgan J, Owen CL, Powell L, Sullivan BC, Tollick H, Wakeman L, Lewis MS, Beddall AC. A capillary whole blood method for measuring the INR. Clin Lab Haematol 2000; 22:279-85. [PMID: 11122269 DOI: 10.1046/j.1365-2257.2000.00331.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
This study describes a method of measuring the INR on native whole blood capillary samples using Innovin recombinant thromboplastin. Modification of the reagent was necessary to compensate for the nonoptimal level of calcium in the sample/reagent mixture. Ninety-five percent of results obtained by the capillary blood method were no more than 0.42 INR higher or 0.38 INR lower than the venous blood method. The effect of changes in haematocrit was minimal. Significant differences in results were found between the Innovin and Thrombotest capillary blood methods. Provided the reagent was properly stored, there was no reagent drift and satisfactory results were obtained on samples supplied by UKNEQAS (coagulation) from previous trials. The method described is a convenient, simple and accurate method of measuring the INR using native capillary whole blood and Innovin recombinant thromboplastin.
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Affiliation(s)
- E J Bamford
- Haematology Department, Neath General Hospital, Pant yr Heol, Neath, UK
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32
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Abstract
The measurement of the concentration distribution of a macromolecule across a solution column by absorption optics usually requires optical transmission profiles of both the sample solution and the buffer, measured under identical conditions, to calculate the absorbance as the logarithm of the ratio of reference to sample intensity. For transport experiments, however, where the changes in the local macromolecule concentration with time are measured, a reference buffer intensity is not necessarily required. We demonstrate that the logarithm of the light transmitted through the sample solution, referred to as pseudo-absorbance, can suffice to determine macromolecular transport parameters of interest, with little loss of precision. Local changes in illumination of the sample column or in the detection efficiency of the transmitted light, as well as temporal fluctuations of the light source intensity can be well-described by consideration of time-invariant and radial-invariant signal components in the pseudo-absorbance data, using the systematic noise decomposition techniques developed recently (Schuck, P., and Demeler, B. (1999) Biophys. J. 76, 2288-2296). The practical use of the method is demonstrated with double-sector and single-sector sedimentation velocity experiments, and with analytical electrophoresis experiments. It is shown that pseudo-absorbance analysis can increase the capacity of a sedimentation velocity experiment in ultracentrifugation, and, in general, can considerably simplify the requirements of optical design.
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Affiliation(s)
- S R Kar
- Molecular Interactions Resource, National Institutes of Health, Bethesda, Maryland 20892, USA.
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Yoo SH, Lewis MS. Interaction of chromogranin B and the near N-terminal region of chromogranin B with an intraluminal loop peptide of the inositol 1,4, 5-trisphosphate receptor. J Biol Chem 2000; 275:30293-300. [PMID: 10906121 DOI: 10.1074/jbc.m001204200] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Given the interaction of the inositol 1,4,5-trisphosphate receptor (IP(3)R) with chromogranins A (CGA) and B (CGB), two major Ca(2+) storage proteins of secretory granules that have been shown to be IP(3)-sensitive intracellular Ca(2+) store of neuroendocrine cells, we have investigated the potential interaction of the intraluminal loop regions of the IP(3)R with both intact CGB and the conserved near N-terminal region of CGB. The interaction studies carried out with CGB and glutathione S-transferase fusion proteins of intraluminal loop regions of bovine type 1 IP(3)R showed that CGB interacts with intraluminal loop 3-2 (the second loop formed between transmembrane regions 5 and 6) of the IP(3)R at both pH 5.5 and 7.5. Analytical ultracentrifugation studies also indicated that CGB interacts with the same intraluminal loop region of the IP(3)R and the interaction was much stronger than that between CGA and the loop. Moreover, the conserved near N-terminal region of CGB also interacted with the intraluminal loop region of the IP(3)R. The CGB interaction with the IP(3)R intraluminal loop peptide at pH 7.5 showed a DeltaG(0) value of -8.1 kcal/mol at 37 degrees C for a 1:1 stoichiometry, indicating a K(d) of approximately 1.9 micrometer. These results give insight into the molecular organization of the IP(3)-sensitive Ca(2+) store.
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Affiliation(s)
- S H Yoo
- National Creative Research Initiative Center for Secretory Granule Research, Biomedical Research Center, Korea Advanced Institute of Science and Technology, Yu Sung Gu, Dae Jeon, Korea 305-701.
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Lewis MS, Wilson RA, Walker K, Stegeman-Olsen J, Norman DJ, Barry JM, Bennett WM. Factors in cardiac risk stratification of candidates for renal transplant. J Cardiovasc Risk 1999; 6:251-5. [PMID: 10501277 DOI: 10.1177/204748739900600410] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Renal transplant candidates are at high risk of fatal and nonfatal cardiac events. METHODS This study evaluated five clinical risk factors--age at least 50 years, insulin-requiring diabetes mellitus, angina, congestive heart failure and an abnormal electrocardiogram (ECG) (excluding left ventricular hypertrophy)--that had been used in the first tier of a two-tiered prospectively applied risk stratification algorithm. RESULTS Using multiple logistic regression analysis, age at least 50 years, abnormal ECG, and diabetes mellitus were independently predictive of cardiac death. Of the two remaining clinical risk factors, the presence of angina had independent predictive value for nonfatal cardiac events (myocardial infarction, coronary angioplasty, bypass surgery, and unstable angina). The independent predictive value of congestive heart failure approached statistical significance. CONCLUSION Clinical risk-factor analysis is helpful in identifying renal transplant candidates at high risk for fatal or nonfatal cardiac events.
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Affiliation(s)
- M S Lewis
- Division of Cardiology, Department of Medicine, Oregon Health Sciences University, Portland 97201, USA
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Abstract
Homologs of the Escherichia coli oxyR gene were identified in several Erwinia species, using a combination of PCR and Southern hybridization analysis. The oxyR gene from Erwinia carotovora was isolated on a cosmid clone and characterized. The gene and deduced gene product shared high level sequence identity with their E. coli counterparts (78 and 89% identity, respectively). In E. coli, the oxyR gene is a transcriptional activator that, under oxidizing conditions, induces expression of a set of oxidative defence genes. OxyR null mutants are, therefore, sensitive to hydrogen peroxide. Introduction of the E. carotovora oxyR gene into an E. coli oxyR mutant resulted in transformants that were hydrogen peroxide resistant, indicating that the Erwinia protein was functional in E. coli.
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Affiliation(s)
- M J Calcutt
- Cancer Research Center, University of Missouri, Columbia, USA
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36
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Dimitriadis EK, Prasad R, Vaske MK, Chen L, Tomkinson AE, Lewis MS, Wilson SH. Thermodynamics of human DNA ligase I trimerization and association with DNA polymerase beta. J Biol Chem 1998; 273:20540-50. [PMID: 9685411 DOI: 10.1074/jbc.273.32.20540] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The interaction between human DNA polymerase beta (pol beta) and DNA ligase I, which appear to be responsible for the gap filling and nick ligation steps in short patch or simple base excision repair, has been examined by affinity chromatography and analytical ultracentrifugation. Domain mapping studies revealed that complex formation is mediated through the non-catalytic N-terminal domain of DNA ligase I and the N-terminal 8-kDa domain of pol beta that interacts with the DNA template and excises 5'-deoxyribose phosphate residue. Intact pol beta, a 39-kDa bi-domain enzyme, undergoes indefinite self-association, forming oligomers of many sizes. The binding sites for self-association reside within the C-terminal 31-kDa domain. DNA ligase I undergoes self-association to form a homotrimer. At temperatures over 18 degreesC, three pol beta monomers attached to the DNA ligase I trimer, forming a stable heterohexamer. In contrast, at lower temperatures (<18 degreesC), pol beta and DNA ligase I formed a stable 1:1 binary complex only. In agreement with the domain mapping studies, the 8-kDa domain of pol beta interacted with DNA ligase I, forming a stable 3:3 complex with DNA ligase I at all temperatures, whereas the 31-kDa domain of pol beta did not. Our results indicate that the association between pol beta and DNA ligase I involves both electrostatic binding and an entropy-driven process. Electrostatic binding dominates the interaction mediated by the 8-kDa domain of pol beta, whereas the entropy-driven aspect of interprotein binding appears to be contributed by the 31-kDa domain.
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Affiliation(s)
- E K Dimitriadis
- Biomedical Engineering and Physical Sciences Program, National Institutes of Health, Bethesda, Maryland 20892, USA
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37
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Stone AL, Melton DJ, Lewis MS. Structure-function relations of heparin-mimetic sulfated xylan oligosaccharides: inhibition of human immunodeficiency virus-1 infectivity in vitro. Glycoconj J 1998; 15:697-712. [PMID: 9881776 DOI: 10.1023/a:1006940632184] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Heparins/heparan sulfates modulate the function of proteins and cell membranes in numerous biological systems including normal and disease processes in humans. Heparin has been used for many years as an anticoagulant, and anticoagulant heparin-mimetics were developed several decades ago by chemical sulfation of non-mammalian polysaccharides, e.g., an antithrombotic sulfated xylan. This pharmaceutical, which comprises a mixture of sulfated oligoxylans, also mimics most other biological actions of natural heparins in vitro, including inhibition of the human immunodeficiency virus, but the molecular basis for these actions has been unclear. Here, numerous Components of the sulfated oligoxylan mixture were isolated and when bioassayed in the case of anti-HIV-1 infectivity revealed that a structural specificity underlines the capacity of sulfated xylan to inhibit HIV-1, rather than a non-specific mechanism. Components were isolated by chromatographic fractionation through Bio-Gel P10 in 0.5 M ammonium bicarbonate. This fractionation revealed an elution range associated with apparent molecular weights of approximately 22000 to <1500 relative to standard heparin and heparan sulfates and newly prepared sulfated oligosaccharide standards. Components were characterized by metachromatic absorption spectroscopy, ultracentrifugation, GlcA analysis, and potency against HIV-1 infectivity, both in the tetrazolium cytotoxicity assay and in syncytium-forming assays, in CD4-lymphocytes. Structural specificity was indicated by the differential potencies exhibited by the Components: Highest activity (cytotoxicity) was exhibited by Components in the chromatographic region > or = approximately 5500 in mass (50% effective (inhibitory) concentration = 0.5-0.7 microg ml(-1) in the first fractionation series, and 0.1-0.5 microg ml(-1) in a second series). The potency declined sharply below approximately 5400 in mass, but with an exception; a second structure exhibiting relatively high potency eluted among low-mass oligosaccharides which had an average size of approximately a nonomer. Components displayed differential potencies also against the syncytium-forming infectivity of HIV-1. The high potency against syncytium-formation was retained by Components down to a minimum size of about 4500 in mass, smaller than the > or = approximately 5400 required above. One in ten of the beta1,4-linked xyloses in the native xylan are substituted with a monomeric alpha1,2 DGlcA branch. We have speculated that pharmaceutical actions of sulfated xylan might be related to structures involving the alpha-D linked substituents and this was examined using a space-filling model of a sulfated octaxylan and by analyses of Components for GlcA content. Understanding structure/function relations in the heparin-like actions of these agents would be of general significance for the careful examination of their potential clinical usefulness in many human processes modulated by heparins, including AIDS.
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Affiliation(s)
- A L Stone
- Laboratory of Developmental and Molecular Immunity, National Institute of Child Health and Human Development, NIH, Bethesda, MD 20892, USA.
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38
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Yoo SH, Lewis MS. Interaction between an intraluminal loop peptide of the inositol 1,4,5-trisphosphate receptor and the near N-terminal peptide of chromogranin A. FEBS Lett 1998; 427:55-8. [PMID: 9613599 DOI: 10.1016/s0014-5793(98)00393-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The near N-terminal region of chromogranin A (CGA) has been shown to be the secretory vesicle membrane binding region, and tetrameric chromogranin A has been demonstrated to bind four molecules of an intraluminal loop peptide of the inositol 1,4,5-trisphosphate (IP3) receptor. It was therefore necessary to determine whether the conserved near N-terminal region of CGA interacts with the intraluminal loop region of the IP3 receptor. In the present study, we found that the proposed anchor region of CGA, the conserved near N-terminal region, does indeed interact with the intraluminal loop region of the IP3 receptor at the intravesicular pH of 5.5, further strengthening the case for the potential interaction between tetrameric chromogranins and tetrameric IP3 receptors in the cell.
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Affiliation(s)
- S H Yoo
- Secretory Granule Research Group, Biomedical Research Center, Korea Advanced Institute of Science and Technology, Daejon, South Korea.
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Seok YJ, Sondej M, Badawi P, Lewis MS, Briggs MC, Jaffe H, Peterkofsky A. High affinity binding and allosteric regulation of Escherichia coli glycogen phosphorylase by the histidine phosphocarrier protein, HPr. J Biol Chem 1997; 272:26511-21. [PMID: 9334229 DOI: 10.1074/jbc.272.42.26511] [Citation(s) in RCA: 73] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
The histidine phosphocarrier protein (HPr) is an essential element in sugar transport by the bacterial phosphoenolpyruvate:sugar phosphotransferase system. Ligand fishing, using surface plasmon resonance, was used to show the binding of HPr to a nonphosphotransferase protein in extracts of Escherichia coli; the protein was subsequently identified as glycogen phosphorylase (GP). The high affinity (association constant approximately 10(8) M-1), species-specific interaction was also demonstrated in electrophoretic mobility shift experiments by polyacrylamide gel electrophoresis. Equilibrium ultracentrifugation analysis indicates that HPr allosterically regulates the oligomeric state of glycogen phosphorylase. HPr binding increases GP activity to 250% of the level in control assays. Kinetic analysis of coupled enzyme assays shows that the binding of HPr to GP causes a decrease in the Km for glycogen and an increase in the Vmax for phosphate, indicating a mixed type activation. The stimulatory effect of E. coli HPr on E. coli GP activity is species-specific, and the unphosphorylated form of HPr activates GP more than does the phosphorylated form. Replacement of specific amino acids in HPr results in reduced GP activation; HPr residues Arg-17, Lys-24, Lys-27, Lys-40, Ser-46, Gln-51, and Lys-72 were established to be important. This novel mechanism for the regulation of GP provides the first evidence directly linking E. coli HPr to the regulation of carbohydrate metabolism.
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Affiliation(s)
- Y J Seok
- NHLBI, National Institutes of Health, Bethesda, Maryland 20892, USA
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40
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Sakaguchi K, Sakamoto H, Lewis MS, Anderson CW, Erickson JW, Appella E, Xie D. Phosphorylation of serine 392 stabilizes the tetramer formation of tumor suppressor protein p53. Biochemistry 1997; 36:10117-24. [PMID: 9254608 DOI: 10.1021/bi970759w] [Citation(s) in RCA: 193] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Tumor suppressor protein p53 is a tetrameric phosphoprotein that activates transcription from several cell cycle regulating genes in response to DNA damage. Tetramer formation is critical to p53's ability to activate transcription; however, posttranslational modifications and protein stabilization also contribute to p53's ability to activate transcription. To determine if phosphorylation affects tetramer formation, we synthesized phosphopeptides corresponding to residues 303-393 of human p53, which includes the domain responsible for tetramer formation. Phosphate was chemically incorporated at Ser315, Ser378, or Ser392 and also at both Ser315 and Ser392. Equilibrium ultracentrifugal analyses showed that phosphorylation at Ser392 increased the association constant for reversible tetramer formation nearly 10-fold. Phosphorylation of either Ser315 or Ser378 had little effect on tetramer formation, but phosphorylation of Ser315 largely reversed the effect of phosphorylation at Ser392. Analyses by calorimetry demonstrated that phosphorylation may influence subunit affinity (and, in turn, DNA binding) by an enthalpy-driven process, possibly between the C-terminal residues and the region immediately adjacent to Ser315. The Kd for the tetramer-monomer transition of the unphosphorylated p53 C-terminal domain was determined to be approximately 1-10 microM. Thus, in normal, undamaged cells p53 may be largely monomeric. Enhancement of tetramer formation through phosphorylation of Ser392, coupled with a DNA-damage-induced increase in its nuclear concentration, could provide a switch that activates p53 as a transcription factor in response to DNA damage.
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Affiliation(s)
- K Sakaguchi
- Laboratory of Cell Biology, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA.
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41
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Sakaguchi K, Sakamoto H, Xie D, Erickson JW, Lewis MS, Anderson CW, Appella E. Effect of phosphorylation on tetramerization of the tumor suppressor protein p53. J Protein Chem 1997; 16:553-6. [PMID: 9246643 DOI: 10.1023/a:1026334116189] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Human tumor suppressor protein p53 is a 393-amino acid phosphoprotein that enhances transcription in response to DNA damage from several genes that regulate cell cycle progression. The tetrameric state of p53 is critical to wild-type function; the p53 tetramerization element is located in the C-terminal region of the protein. This region is phosphorylated at several evolutionarily conserved serines, suggesting that phosphorylation may be an important regulator of p53 function. In order to determine the effect of phosphorylation on tetramer formation, we synthesized phosphopeptides corresponding to p53(Ser303-Asp393) with phosphate incorporated at Ser315, Ser378, or Ser392, and at both Ser315 and Ser392. Equilibrium ultracentrifugation analysis showed that phosphorylation at Ser392 increased the association constant for tetramer formation nearly ten-fold. By itself, phosphorylation at Ser315 or Ser378 had little effect on tetramer formation, but Ser315 largely reversed the effect of phosphorylation at Ser392. Analysis by calorimetry suggests that phosphorylation may influence subunit affinity by an enthalpy driven process.
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Affiliation(s)
- K Sakaguchi
- Laboratory of Cell Biology, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA
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Lee SP, Xiao J, Knutson JR, Lewis MS, Han MK. Zn2+ promotes the self-association of human immunodeficiency virus type-1 integrase in vitro. Biochemistry 1997. [PMID: 8993331 DOI: 10.1021/bi961849obi961849o] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
It has been recently demonstrated that the Mg(2+)-dependent 3'-processing activity of purified human immunodeficiency virus type-1 (HIV-1) integrase is stimulated by the addition of exogenous Zn2+ [Lee, S. P., & Han, M. K. (1996) Biochemistry 35, 3837-3844]. This activation was hypothesized to result from integrase self-association. In this report, we examine the Zn2+ content of purified HIV-1 integrase by atomic absorption spectroscopy and by application of a thiol modification reagent, p-(hydroxymercuri)benzenesulfonate, with a metallochromic indicator, 4-(2-pyridylazo)resorcinol. We find that the Zn2+ content of HIV-1 integrase varies from 0.1 to 0.92 equiv of Zn2+ per monomer depending on the conditions of protein purification. In vitro activity assays, time-resolved fluorescence emission anisotropy, and gel filtration chromatographic analyses all indicate that EDTA yields an apoprotein which is predominantly monomeric and less active with Mg2+. Further, sedimentation equilibrium studies reveal that reconstitution of the apoprotein with Zn2+ results in a monomer-tetramer-octamer transition. These results suggest that Zn2+ promotes a conformation with enhanced oligomerization and thereby stimulates Mg(2+)-dependent 3'-processing. This may also imply that multimers larger than dimers (tetramers and possibly octamers) are required for in vitro activity of integrase in the presence of Zn2+ and Mg2+. It should be noted, however, that the content of Zn2+ did not significantly affect the 3'-processing and strand transfer reactions with Mn2+ in vitro.
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Affiliation(s)
- S P Lee
- Department of Biochemistry and Molecular Biology, Georgetown University Medical Center, Washington, DC 20007, USA
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43
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Abstract
It has been recently demonstrated that the Mg(2+)-dependent 3'-processing activity of purified human immunodeficiency virus type-1 (HIV-1) integrase is stimulated by the addition of exogenous Zn2+ [Lee, S. P., & Han, M. K. (1996) Biochemistry 35, 3837-3844]. This activation was hypothesized to result from integrase self-association. In this report, we examine the Zn2+ content of purified HIV-1 integrase by atomic absorption spectroscopy and by application of a thiol modification reagent, p-(hydroxymercuri)benzenesulfonate, with a metallochromic indicator, 4-(2-pyridylazo)resorcinol. We find that the Zn2+ content of HIV-1 integrase varies from 0.1 to 0.92 equiv of Zn2+ per monomer depending on the conditions of protein purification. In vitro activity assays, time-resolved fluorescence emission anisotropy, and gel filtration chromatographic analyses all indicate that EDTA yields an apoprotein which is predominantly monomeric and less active with Mg2+. Further, sedimentation equilibrium studies reveal that reconstitution of the apoprotein with Zn2+ results in a monomer-tetramer-octamer transition. These results suggest that Zn2+ promotes a conformation with enhanced oligomerization and thereby stimulates Mg(2+)-dependent 3'-processing. This may also imply that multimers larger than dimers (tetramers and possibly octamers) are required for in vitro activity of integrase in the presence of Zn2+ and Mg2+. It should be noted, however, that the content of Zn2+ did not significantly affect the 3'-processing and strand transfer reactions with Mn2+ in vitro.
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Affiliation(s)
- S P Lee
- Department of Biochemistry and Molecular Biology, Georgetown University Medical Center, Washington, DC 20007, USA
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44
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Sakamoto H, Kodama H, Higashimoto Y, Kondo M, Lewis MS, Anderson CW, Appella E, Sakaguchi K. Chemical synthesis of phosphorylated peptides of the carboxy-terminal domain of human p53 by a segment condensation method. Int J Pept Protein Res 1996; 48:429-42. [PMID: 8956076 DOI: 10.1111/j.1399-3011.1996.tb00861.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
A segment condensation method was developed for the chemical synthesis of large (> 90 amino acid) phosphopeptides and was used to produce phosphorylated and non-phosphorylated derivatives of the C-terminal tetramerization and regulatory domains of human p53 (residues 303-393). Efficient condensation synthesis of the 91 residue p53 domain was achieved in two steps. The non-phosphorylated N-terminal segment p53(303-334) (1) and its derivative phosphorylated at serine 315 (1P315), and the non-phosphorylated middle segment p53(335-360) (2), were synthesized as partially protected peptide thioesters in the solid phase using Boc chemistry. The C-terminal segment p53(361-393) (3) and its derivative phosphorylated at serine 392 (3P392) were synthesized as partially protected peptides in the solid phase using Fmoc chemistry. Phosphoamino acid was incorporated into the N-terminal segment (1P315) at the residue corresponding to p53 serine 315 as Boc-Ser(PO3(Bzl)2)-OH during synthesis. Serine 392 in the C-terminal segment was selectively phosphorylated after synthesis by phosphitylation followed by oxidation. A derivative phosphorylated at serine 378 was synthesized in a one-step condensation of the unphosphorylated N-terminal segment (1) and the phosphorylated long C-terminal segment p53(335-393) (2-3P378). Yields of the ligated peptides after removal of the protecting groups and HPLC purification averaged 60% for the first condensation and 35% for the second condensation. All five p53 peptides exhibited monomer-tetramer association as determined by analytical ultracentrifugation. Circular dichroism spectroscopy revealed that phosphorylation at Ser315 increased the alpha-helical content, which was abolished when Ser392 also was phosphorylated, suggesting an interaction between N-terminal and C-terminal residues of the C-terminal domain of p53.
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Affiliation(s)
- H Sakamoto
- Laboratory of Cell Biology, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, USA
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45
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Robey FA, Harris-Kelson T, Robert-Guroff M, Batinić D, Ivanov B, Lewis MS, Roller PP. A synthetic conformational epitope from the C4 domain of HIV Gp120 that binds CD4. J Biol Chem 1996; 271:17990-5. [PMID: 8663408 DOI: 10.1074/jbc.271.30.17990] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
The fourth conserved domain of the human immunodeficiency virus type 1 (HIV-1) envelope, the C4 region of glycoprotein 120 (gp120), is believed to be a major part of gp120 that is necessary for binding to CD4. Recently, we found that C4 in gp120 is probably an alpha-helix, because antibodies made against helical constructs of C4 react with native and recombinant gp120 but antibodies against linear C4 constructs do not. For the present study, we performed experiments to determine, first, if CD4 could bind to the helical C4 constructs and, second, if the binding was comparable with CD4 binding to gp120. Immobilized helical constructs derived from the C4s from HIV-1 and HIV-2 bound biotinylated recombinant CD4 with Kd values of 8.59 nM and 14.59 nM, respectively. Recombinant soluble CD4 inhibited the binding of biotinylated CD4 to the C4 construct from HIV-1 with a Kd of 9.88 nM, and recombinant gp120 blocked the binding of CD4 to the immobilized helical construct from C4 of HIV-1 with a Kd of 8.08 nM. The C4 peptide-(419-436) from HIV-1 (KIKQIINMWQEVGKAMYA-NH2) blocked CD4 binding to gp120 but only in a buffer containing 0.03% Brij 35 where the peptide displayed 17 +/- 1% alpha-helix; without the Brij 35, peptide-(419-436) displayed no helical content. The Kd for the peptide-(419-436) blocking CD4 binding to gp120 in Brij 35-containing buffer was found to be 42 microM. These results indicate that C4 constructs from HIV-1 and HIV-2 do bind CD4, but the constructs must display an alpha-helical conformation to do so. In addition, the results reported here will provide answers to key questions about structural requirements for HIV vaccines and therapeutics that hinge on understanding the molecular nature of the gp120-CD4 interaction as the first step in the HIV infection process.
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Affiliation(s)
- F A Robey
- Peptide and Immunochemistry Unit, NIDR, National Institutes of Health Bethesda, Maryland 20892, USA
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Abstract
The two major proteins of the secretory vesicles of neuroendocrine cells, chromogranin A (CGA) and chromogranin B (CGB), have been shown to undergo pH- and Ca2+-dependent conformational changes and aggregation and have been suggested to play essential roles during secretory vesicle biogenesis in the trans-Golgi network. CGA has been shown to exist primarily in a tetrameric state at pH 5.5 and primarily in a dimeric state at pH 7.5, and CGB has been shown to exist in a monomeric state at both pH 5.5 and pH 7.5. Using purified CGA and CGB, it recently has been shown that CGA interacts with CGB at pH 5.5 (Yoo, S. H.(1996) J. Biol. Chem. 271, 1558-1565). In expanding this investigation, we have studied the temperature dependence of the pH-dependent interaction of CGA and CGB by analytical ultracentrifugation and found that two molecules of CGA bound to two molecules of CGB at pH 5.5 with DeltaG0 values of -43.6 kcal/mol in the absence of Ca2+ at 37 degrees C and -40.3 kcal/mol in the presence of 0.1 mM Ca2+. However, one molecule of CGA bound to one molecule of CGB at pH 7.5 with DeltaG0 values of -13.6 kcal/mol in the absence of Ca2+ at 37 degrees C. The magnitude of DeltaG0 values increased with increasing temperatures at both pH values. However, the values for enthalpy and entropy changes decreased with increasing temperatures in both pH levels, suggesting formation of more ordered structures. In the absence of Ca2+ at pH 5. 5, the heterotetramerization reaction at 37 degrees C was entropically driven, whereas in the presence of Ca2+ (0.1 mM) the heterotetramerization was virtually an enthalpic reaction. On the other hand, the heterodimer formation in the absence of Ca2+ at pH 7. 5 showed large negative enthalpy and entropy changes at 37 degrees C, indicating an enthalpic interaction compensated by entropic changes. In view of the interaction of tetrameric CGA with tetrameric inositol 1,4,5-trisphosphate (IP3) receptor and the existence of heterotetrameric IP3 receptor in the cell, the heterotetramer formation by CGA and CGB not only raises the possibility of interaction between the heterotetrameric chromogranin and heterotetrameric IP3 receptor but also appears to reflect their important roles in the cell.
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Affiliation(s)
- S H Yoo
- Laboratory of Neurochemistry, NIDCD, National Institutes of Health, Bethesda, Maryland 20892, USA
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Junghans RP, Stone AL, Lewis MS. Biophysical characterization of a recombinant soluble interleukin 2 receptor (Tac). Evidence for a monomeric structure. J Biol Chem 1996; 271:10453-60. [PMID: 8631840 DOI: 10.1074/jbc.271.18.10453] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
The interleukin 2 receptor (IL2R) plays a prominent role in the biology of T cells, B cells, and NK cells during activation. Of the three chains described, the alpha-chain of the receptor (Tac; IL2R alpha; CD25) is the most subject to regulation and is shed from the surface of activated cells to generate a soluble form in serum and tissues. Conflicting results have been reported on the native structure of soluble Tac, suggesting variously a monomer, a dimer, or higher noncovalent forms, spawning different models for its mechanism of action. We similarly show a large M(r)(app) by HPLC sieving chromatography, suggesting a tetrameric form. However, stoichiometry-ordered size (SOS) analysis of antibody-antigen complexes indicated only a single epitope per Tac molecule, compatible with a monomeric form. This larger M(r)(app) also conflicted with prior in vivo data showing rapid filtration of soluble Tac through the renal glomerulus that was not expected of a larger complex. Using different solvents, denaturants, and columns in the chromatography suggested that the elevated M(r)(app) values were an artifact of solute-column interactions, termed "ionic exclusion", rather than reflecting larger native structures. Analytical ultracentrifugation using a new type of analysis specific to glycoproteins demonstrated monomeric masses under all salt conditions with no tendency to form dimers or higher aggregates. Finally, circular dichroism spectroscopy showed no salt-dependent changes to suggest conformational alterations that might correlate with mobility changes on high pressure liquid chromatography. We conclude therefore that Tac is monomeric under physiologic conditions. Assessments of higher molecular weight for the purified soluble protein by other methods may be explained by the highly acidic nature of the molecule, which hampers matrix penetration with chromatographic media and by the high carbohydrate content and low partial specific volumes that accelerate the molecule in sedimentation media relative to pure protein standards.
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Affiliation(s)
- R P Junghans
- Division of Hematology-Oncology, Harvard Medical School, New England Deaconess Hospital, Boston, Massachusetts 02215, USA
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Chattoraj DK, Ghirlando R, Park K, Dibbens JA, Lewis MS. Dissociation kinetics of RepA dimers: implications for mechanisms of activation of DNA binding by chaperones. Genes Cells 1996; 1:189-99. [PMID: 9140063 DOI: 10.1046/j.1365-2443.1996.d01-235.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
BACKGROUND The replication initiator of plasmid P1, RepA, binds DNA as monomer. The binding is stimulated by the chaperones DnaJ, DnaK and GrpE of Escherichia coli. Two models of chaperone action have been proposed. (i) Chaperones dissociate RepA dimers, which are inactive in DNA binding, into active monomers. (ii) The dissociation occurs spontaneously but the monomeric products require the chaperones for refolding into the active form. The latter model was based on the observation that RepA diluted 1000-fold below the K(D) for dimer dissociation, still required the chaperones for DNA binding. RESULTS We have confirmed that under the condition of DNA binding experiments, the RepA dimers dissociate reversibly into monomers with a K(D) value of 1.1 +/- 0.1 microM. In the vicinity of this concentration, the sedimentation coefficient of RepA was concentration dependent, allowing estimation of s(20,w) coefficients for the RepA monomer (2.95 S) and dimer (4.01 S). Dynamic light scattering experiments indicated an increase of the monomer fraction within 5 min of RepA dilution. Circular dichroism (CD) measurements were consistent with these results. CONCLUSION RepA monomerization is efficient without the mediation of chaperones. They are required to activate RepA most likely because they are needed to re-fold RepA monomers.
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Affiliation(s)
- D K Chattoraj
- Laboratory of Biochemistry, NCI, National Institutes of Health, Bethesda, MD 20892, USA
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Ghirlando R, Keown MB, Mackay GA, Lewis MS, Unkeless JC, Gould HJ. Stoichiometry and thermodynamics of the interaction between the Fc fragment of human IgG1 and its low-affinity receptor Fc gamma RIII. Biochemistry 1995; 34:13320-7. [PMID: 7577916 DOI: 10.1021/bi00041a007] [Citation(s) in RCA: 50] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
IgG-Fc receptors, cell surface glycoproteins binding the Fc region of antibodies, play a crucial role in the immune system. To better understand the nature of the recognition process, we have examined the interaction between huIgG1-Fc and a soluble fragment of huFc gamma RIII (sCD16). Analytical ultracentrifugation experiments clearly demonstrate that IgG1-Fc and sCD16 interact weakly to form a 1:1 complex with an association constant of 1.7 x 10(5) M-1 in PBS at 22.0 degrees C. The thermodynamic parameters, obtained from the temperature dependence of the equilibrium binding constants, exhibit an enthalpy-entropy compensation with a favorable enthalpy at physiological temperatures. The value of -360 cal mol-1 K-1 for delta Cp zero possibly identifies the process as one in which local folding/rearrangement is coupled to complex formation. The 1:1 stoichiometry and thermodynamic parameters provide a basis for understanding the nature of the Fc gamma R-IgG interactions.
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Affiliation(s)
- R Ghirlando
- Laboratory of Molecular Biology, National Institute of Diabetes, Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA
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Balagurumoorthy P, Sakamoto H, Lewis MS, Zambrano N, Clore GM, Gronenborn AM, Appella E, Harrington RE. Four p53 DNA-binding domain peptides bind natural p53-response elements and bend the DNA. Proc Natl Acad Sci U S A 1995; 92:8591-5. [PMID: 7567980 PMCID: PMC41012 DOI: 10.1073/pnas.92.19.8591] [Citation(s) in RCA: 106] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Recent structural studies of the minimal core DNA-binding domain of p53 (p53DBD) complexed to a single consensus pentamer sequence and of the isolated p53 tetramerization domain have provided valuable insights into their functions, but many questions about their interacting roles and synergism remain unanswered. To better understand these relationships, we have examined the binding of the p53DBD to two biologically important full-response elements (the WAF1 and ribosomal gene cluster sites) by using DNA circularization and analytical ultracentrifugation. We show that the p53DBD binds DNA strongly and cooperatively with p53DBD to DNA binding stoichiometries of 4:1. For the WAF1 element, the mean apparent Kd is (8.3 +/- 1.4) x 10(-8) M, and no intermediate species of lower stoichiometries can be detected. We show further that complex formation induces an axial bend of at least 60 degrees in both response elements. These results, taken collectively, demonstrate that p53DBD possesses the ability to direct the formation of a tight nucleoprotein complex having the same 4:1 DNA-binding stoichiometry as wild-type p53 which is accompanied by a substantial conformational change in the response-element DNA. This suggests that the p53DBD may play a role in the tetramerization function of p53. A possible role in this regard is proposed.
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Affiliation(s)
- P Balagurumoorthy
- Department of Biochemistry, University of Nevada Reno 89557-0014, USA
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