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Chiang A, Tam K, Au-Yeung R. COMBINED BORTEZOMIB AND VENETOCLAX TARGETS THE PRO-SURVIVAL FUNCTIONS OF LATENT VIRAL PROTEINS IN EPSTEIN-BARR VIRUS-DRIVEN LYMPHOPROLIFERATIVE DISEASES. Leuk Res 2022. [DOI: 10.1016/s0145-2126(22)00228-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Boguslawski KM, McKeown AN, Day CJ, Lacey KA, Tam K, Vozhilla N, Kim SY, Jennings MP, Koralov SB, Elde NC, Torres VJ. Exploiting species specificity to understand the tropism of a human-specific toxin. Sci Adv 2020; 6:eaax7515. [PMID: 32195339 PMCID: PMC7065885 DOI: 10.1126/sciadv.aax7515] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/18/2019] [Accepted: 12/17/2019] [Indexed: 06/10/2023]
Abstract
Many pathogens produce virulence factors that are specific toward their natural host. Clinically relevant methicillin-resistant Staphylococcus aureus (MRSA) isolates are highly adapted to humans and produce an array of human-specific virulence factors. One such factor is LukAB, a recently identified pore-forming toxin that targets human phagocytes by binding to the integrin component CD11b. LukAB exhibits strong tropism toward human, but not murine, CD11b. Here, phylogenetics and biochemical studies lead to the identification of an 11-residue domain required for the specificity of LukAB toward human CD11b, which is sufficient to render murine CD11b compatible with toxin binding. CRISPR-mediated gene editing was used to replace this domain, resulting in a "humanized" mouse. In vivo studies revealed that the humanized mice exhibit enhanced susceptibility to MRSA bloodstream infection, a phenotype mediated by LukAB. Thus, these studies establish LukAB as an important toxin for MRSA bacteremia and describe a new mouse model to study MRSA pathobiology.
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Affiliation(s)
- K. M. Boguslawski
- Department of Microbiology, New York University School of Medicine, New York, NY 10016, USA
| | - A. N. McKeown
- Department of Human Genetics, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - C. J. Day
- Institute for Glycomics, Griffith University, Gold Coast, QLD 4222, Australia
| | - K. A. Lacey
- Department of Microbiology, New York University School of Medicine, New York, NY 10016, USA
| | - K. Tam
- Department of Microbiology, New York University School of Medicine, New York, NY 10016, USA
| | - N. Vozhilla
- Department of Microbiology, New York University School of Medicine, New York, NY 10016, USA
| | - S. Y. Kim
- Office of Collaborative Sciences, New York University School of Medicine, New York, NY 10016, USA
- Department of Pathology, New York University School of Medicine, New York, NY 10016, USA
| | - M. P. Jennings
- Institute for Glycomics, Griffith University, Gold Coast, QLD 4222, Australia
| | - S. B. Koralov
- Department of Pathology, New York University School of Medicine, New York, NY 10016, USA
| | - N. C. Elde
- Department of Human Genetics, University of Utah School of Medicine, Salt Lake City, UT 84112, USA
| | - V. J. Torres
- Department of Microbiology, New York University School of Medicine, New York, NY 10016, USA
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Harbtn DN, Amleh A, Bernes A, Bodzian F, Boyer K, Conaway J, Dias H, Dommarco R, Duverney-Pret P, Earnest S, Ely D, Fornarelli L, Förster R, Gentry G, Görlitz G, Gomez F, Guess P, Hähnchen K, Hamilton D, Halley M, Hathaway M, Hickes H, Isono K, Kulinna H, Lucas P, Manger P, Manso L, Moffett S, Müller T, Orii T, Paul R, Reubke K, Rivera L, Rubbiani M, Schetter J, Schulz D, Shaocong L, Smead F, Tam K, Tengler H, Torma L, del Valle M, Verweij A, Walls G, Weiping G. Quantitation of Tebuconazole in Liquid and Solid Formulations by Capillary GC: Collaborative Study. J AOAC Int 2020. [DOI: 10.1093/jaoac/80.4.703] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
Abstract
A capillary gas chromatographic method has been developed for quantitation of tebuconazole (Folicur, Elite, Raxil, Lynx) in liquid and solid formulations. Tebuconazole is a broad-spectrum, systemic foliar fungicide used to control diseases of wheat, barley, peanut, and grasses grown for seed. Samples are dissolved in acetone and analyzed by capillary gas chromatography (GC) with dicyclohexyl phthalate as internal standard. Twenty-two laboratories from 11 countries participated in a collaborative study of the method. Each collaborator was provided reference standard, internal standard, and blind duplicate samples from 6 formulations: aqueous flowable (F), aqueous emulsifiable concentrate (EW), emulsifiable concentrate for seed treatment (ES), flowable for seed treatment (FS), wettable powder (WP), and dry flowable (DF). Collaborators were instructed to use peak area measurements for quantitation. The seed treatment flowable formulation required confirmation of accurate integration values by the collaborator. Relative standard deviation values for reproducibility (RSDR) for analysis of the formulations were as follows: 3.6 lb/gal F, 1.22; 250 g/L EW, 1.13; 15 g/L ES, 2.40; 25 g/L FS, 2.65; 25% WP, 0.96; 25% DF, 0.72; 45% DF, 0.72. The capillary GC method for quantitation of tebuconazole in fungicide formulations has been adopted first action by AOAC INTERNATIONAL.
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Affiliation(s)
- Donald N Harbtn
- Bayer Corporation, Agriculture Division, PO Box 4913, 8400 Hawthorne Rd, Kansas City, MO 64120-0013
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Raj V, Claudine S, Subramanian A, Tam K, Biswas A, Bongso A, Fong CY. Histological, immunohistochemical, and genomic evaluation of excisional and diabetic wounds treated with human Wharton's jelly stem cells with and without a nanocarrier. J Cell Biochem 2019; 120:11222-11240. [PMID: 30706534 DOI: 10.1002/jcb.28398] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2018] [Revised: 12/15/2018] [Accepted: 01/10/2019] [Indexed: 01/24/2023]
Abstract
We showed in previous studies that human umbilical cord Wharton's jelly stem cells (hWJSCs) improved the healing rates of excisional and diabetic wounds in the mouse model. As an extension of those studies, we report here the more detailed quantitative histological, immunohistochemical, and genomic evaluation of biopsies from those excisional and diabetic wounds in an attempt to understand the mechanisms of the enhanced wound healing aided by hWJSCs. Bright-field microscopic observations and ImageJ software analysis on histological sections of the excisional and diabetic wound biopsies collected at different time points showed that the thickness of the epidermis and dermis, and positive picrosirius-red stained areas for collagen, were significantly greater in the presence of hWJSCs compared with controls (P < 0.05). Immunohistochemistry of the diabetic wound biopsies showed increased positive staining for the vascular endothelial marker CD31 and cell proliferation marker Ki67 in the presence of hWJSCs and its conditioned medium (hWJSC-CM). Quantitative real-time polymerase chain reaction showed upregulation of groups of genes involved in extracellular matrix regulation, collagen biosynthesis, angiogenesis, antifibrosis, granulation, and immunomodulation in the presence of hWJSCs. Taken together, the results demonstrated that hWJSCs and hWJSC-CM that contains the paracrine secretions of hWJSCs, enhance the healing of excisional and diabetic wounds via re-epithelialization, collagen deposition, angiogenesis, and immunomodulation. The inclusion of an Aloe vera-polycaprolactone (AV/PCL) nanocarrier did not significantly change the effect of the hWJSCs. However, the topical application of an AV/PCL nanocarrier impregnated with hWJSCs is convenient and less invasive than the administration of hWJSC injections into wounds.
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Affiliation(s)
- Vaishnevi Raj
- Department of Obstetrics and Gynaecology, Yong Loo Lin School of Medicine, National University Health System, National University of Singapore, Singapore
| | - Stephanie Claudine
- Department of Obstetrics and Gynaecology, Yong Loo Lin School of Medicine, National University Health System, National University of Singapore, Singapore
| | - Arjunan Subramanian
- Department of Obstetrics and Gynaecology, Yong Loo Lin School of Medicine, National University Health System, National University of Singapore, Singapore
| | - Kimberley Tam
- BioSystems and Micromechanics IRG, Singapore-MIT Alliance in Research and Technology, Singapore
| | - Arijit Biswas
- Department of Obstetrics and Gynaecology, Yong Loo Lin School of Medicine, National University Health System, National University of Singapore, Singapore
| | - Ariff Bongso
- Department of Obstetrics and Gynaecology, Yong Loo Lin School of Medicine, National University Health System, National University of Singapore, Singapore
| | - Chui-Yee Fong
- Department of Obstetrics and Gynaecology, Yong Loo Lin School of Medicine, National University Health System, National University of Singapore, Singapore
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Liu FD, Tam K, Pishesha N, Poon Z, Van Vliet KJ. Improving hematopoietic recovery through modeling and modulation of the mesenchymal stromal cell secretome. Stem Cell Res Ther 2018; 9:268. [PMID: 30352620 PMCID: PMC6199758 DOI: 10.1186/s13287-018-0982-2] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [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: 03/07/2018] [Revised: 08/13/2018] [Accepted: 08/15/2018] [Indexed: 12/11/2022] Open
Abstract
BACKGROUND Efficient and sustained hematopoietic recovery after hematopoietic stem cell or bone marrow transplantation is supported by paracrine signaling from specific subpopulations of mesenchymal stromal cells (MSCs). Here, we considered whether in vitro mechanopriming of human MSCs could be administered to predictively and significantly improve in vivo hematopoietic recovery after irradiation injury. METHODS First, we implemented regression modeling to identify eight MSC-secreted proteins that correlated strongly with improved rescue from radiation damage, including hematopoietic recovery, in a murine model of hematopoietic failure. Using these partial least squares regression (PLSR) model parameters, we then predicted recovery potential of MSC populations that were culture expanded on substrata of varying mechanical stiffness. Lastly, we experimentally validated these predictions using an in vitro co-culture model of hematopoiesis and using new in vivo experiments for the same irradiation injury model used to generate survival predictions. RESULTS MSCs grown on the least stiff (elastic moduli ~ 1 kPa) of these polydimethylsiloxane (PDMS) substrata secreted high concentrations of key proteins identified in regression modeling, at concentrations comparable to those secreted by minor subpopulations of MSCs shown previously to be effective in supporting such radiation rescue. We confirmed that these MSCs expanded on PDMS could promote hematopoiesis in an in vitro co-culture model with hematopoietic stem and progenitor cells (HSPCs). Further, MSCs cultured on PDMS of highest stiffness (elastic moduli ~ 100 kPa) promoted expression of CD123+ HSPCs, indicative of myeloid differentiation. Systemic administration of mechanoprimed MSCs resulted in improved mouse survival and weight recovery after bone marrow ablation, as compared with both standard MSC expansion on stiffer materials and with biophysically sorted MSC subpopulations. Additionally, we observed recovery of white blood cells, platelets, and red blood cells, indicative of complete recovery of all hematopoietic lineages. CONCLUSIONS These results demonstrate that computational techniques to identify MSC biomarkers can be leveraged to predict and engineer therapeutically effective MSC phenotypes defined by mechanoprimed secreted factors, for translational applications including hematopoietic recovery.
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Affiliation(s)
- Frances D. Liu
- Department of Biological Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139 USA
- Biosystems and Micromechanics (BioSyM) Interdisciplinary Research Group, Singapore-MIT Alliance for Research and Technology, 1 Create Way, Singapore, 138602 Singapore
| | - Kimberley Tam
- Biosystems and Micromechanics (BioSyM) Interdisciplinary Research Group, Singapore-MIT Alliance for Research and Technology, 1 Create Way, Singapore, 138602 Singapore
| | - Novalia Pishesha
- Department of Biological Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139 USA
- Whitehead Institute for Biomedical Research, 455 Main Street, Cambridge, MA 02139 USA
| | - Zhiyong Poon
- Biosystems and Micromechanics (BioSyM) Interdisciplinary Research Group, Singapore-MIT Alliance for Research and Technology, 1 Create Way, Singapore, 138602 Singapore
| | - Krystyn J. Van Vliet
- Department of Biological Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139 USA
- Biosystems and Micromechanics (BioSyM) Interdisciplinary Research Group, Singapore-MIT Alliance for Research and Technology, 1 Create Way, Singapore, 138602 Singapore
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139 USA
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Tam K, Tang I, Ho J, Yeung W, Lee CK, Ip P, Kwok J. A study of human neutrophil antigen genotype frequencies in Hong Kong. Transfus Med 2017; 28:310-318. [PMID: 29280200 DOI: 10.1111/tme.12494] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2016] [Revised: 07/07/2017] [Accepted: 11/19/2017] [Indexed: 11/29/2022]
Abstract
BACKGROUND Alloantibodies against human neutrophil antigens (HNA) are associated with a variety of clinical conditions. Over the past decade, the allelic and genotypic frequencies of the five HNA systems have been evaluated. Although the HNA system is less polymorphic than human leukocyte antigens (HLA), significant differences in the genotypic and allele frequencies still exist in different populations, even those living in close proximity. OBJECTIVES To delineate HNA genotypic and allele frequencies to provide vital information on estimating the risk of HNA-associated diseases for our local population. METHODS Using a validated, in-house-developed assay, genotyping for HNA-1, HNA-3, HLA-4 and HNA-5 was performed on 300 samples from Chinese blood donors from Hong Kong. In addition, the frequency of the HNA-2 c.843A > T allele was also determined. RESULTS The allele frequencies of HNA-1a, -1b and -1c alleles were 67·8, 31·5 and 0%, respectively, whereas the frequencies of HNA-3a and HNA-3b were 71·0 and 29·0%, respectively. The frequencies of HNA-4a and -4b alleles were 99·5 and 0·5%, respectively, and for HNA-5a and -5b, alleles were 85·2 and 14·8%, respectively. Homozygotes for the HNA-2 c.843 TT variant were absent in our population, whereas only <4% of the population were c.843AT heterozygote carriers. CONCLUSIONS This is the first study to define HNA genotype and allele frequencies using a validated modified in-house PCR-SSP method in the Hong Kong Chinese blood donor population. Our approach provides a cost-effective assay for conducting routine HNA typing and facilitates the incorporation of these assays into routine clinical service. Our results are comparable with those reported in the Guangzhou Chinese population, but the allele frequencies in our Hong Kong Chinese population are significantly different from the reported European frequencies, confirming that a geographical difference exists for HNA allele frequencies.
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Affiliation(s)
- K Tam
- Division of Transplantation and Immunogenetics, Department of Pathology, Queen Mary Hospital, Hong Kong SAR, China
| | - I Tang
- Division of Transplantation and Immunogenetics, Department of Pathology, Queen Mary Hospital, Hong Kong SAR, China
| | - J Ho
- Division of Transplantation and Immunogenetics, Department of Pathology, Queen Mary Hospital, Hong Kong SAR, China
| | - W Yeung
- Division of Transplantation and Immunogenetics, Department of Pathology, Queen Mary Hospital, Hong Kong SAR, China
| | - C K Lee
- Hong Kong Red Cross Blood Transfusion Service, Kowloon, Hong Kong SAR, China
| | - P Ip
- Department of Paediatrics & Adolescent Medicine, University of Hong Kong, Hong Kong SAR, China
| | - J Kwok
- Division of Transplantation and Immunogenetics, Department of Pathology, Queen Mary Hospital, Hong Kong SAR, China
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Flores R, Taioli E, Yankelevitz D, Yip R, Becker B, Jirapatnakul A, Reeves A, Schwartz R, Tam K, Henschke C. P2.16-022 Initiative for Early Lung Cancer Research on Treatment: Pilot Implementation. J Thorac Oncol 2017. [DOI: 10.1016/j.jtho.2017.09.1431] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Fong CY, Tam K, Cheyyatraivendran S, Gan SU, Gauthaman K, Jeyaseelan K, Choolani M, Biswas A, Bongso A. Erratum: Human Wharton's Jelly Stem Cells and Its Conditioned Medium Enhance Healing of Excisional and Diabetic Wounds. J Cell Biochem 2017; 118:3016. [PMID: 28704592 DOI: 10.1002/jcb.26081] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [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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Tam K, Cheyyatraviendran S, Venugopal J, Biswas A, Choolani M, Ramakrishna S, Bongso A, Fong CY. Erratum: A Nanoscaffold Impregnated With Human Wharton's Jelly Stem Cells or Its Secretions Improves Healing of Wounds. J Cell Biochem 2017; 118:3017. [PMID: 28704591 DOI: 10.1002/jcb.26082] [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: 11/11/2022]
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Grover S, Lowensteyn I, Wang J, Tam K, Grover S, Rempel P. CHALLENGES IN TREATING DYSLIPIDEMIA AMONG CANADIANS: FACTORS ASSOCIATED WITH SUB-OPTIMAL ADHERENCE TO MEDICATION. Can J Cardiol 2014. [DOI: 10.1016/j.cjca.2014.07.536] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022] Open
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Fong CY, Tam K, Cheyyatraivendran S, Gan SU, Gauthaman K, Armugam A, Jeyaseelan K, Choolani M, Biswas A, Bongso A. Human Wharton's jelly stem cells and its conditioned medium enhance healing of excisional and diabetic wounds. J Cell Biochem 2014; 115:290-302. [PMID: 24038311 DOI: 10.1002/jcb.24661] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2013] [Accepted: 08/20/2013] [Indexed: 12/21/2022]
Abstract
Wound healing is a major problem in diabetic patients and current treatments have met with limited success. We evaluated the treatment of excisional and diabetic wounds using a stem cell isolated from the human umbilical cord Wharton's jelly (hWJSC) that shares unique properties with embryonic and adult mesenchymal stem cells. hWJSCs are non-controversial, available in abundance, hypo-immunogenic, non-tumorigenic, differentiate into keratinocytes, and secrete important molecules for tissue repair. When human skin fibroblasts (CCD) in conventional scratch-wound assays were exposed to hWJSC-conditioned medium (hWJSC-CM) the fibroblasts at the wound edges migrated and completely covered the spaces by day 2 compared to controls. The number of invaded cells, cell viability, total collagen, elastin, and fibronectin levels were significantly greater in the hWJSC-CM treatment arm compared to controls (P < 0.05). When a single application of green fluorescent protein (GFP)-labeled hWJSCs (GFP-hWJSCs) or hWJSC-CM was administered to full-thickness murine excisional and diabetic wounds, healing rates were significantly greater compared to controls (P < 0.05). Wound biopsies collected at various time points showed the presence of green GFP-labeled hWJSCs, positive human keratinocyte markers (cytokeratin, involucrin, filaggrin) and expression of ICAM-1, TIMP-1, and VEGF-A. On histology, the GFP-hWJSCs and hWJSC-CM treated wounds showed reepithelialization, increased vascularity and cellular density and increased sebaceous gland and hair follicle numbers compared to controls. hWJSCs showed increased expression of several miRNAs associated with wound healing compared to CCDs. Our studies demonstrated that hWJSCs enhance healing of excisional and diabetic wounds via differentiation into keratinocytes and release of important molecules.
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Affiliation(s)
- Chui-Yee Fong
- Department of Obstetrics and Gynaecology, Yong Loo Lin School of Medicine, National University Health System, National University of Singapore, Singapore, 119228, Singapore
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Tam K, Cheyyatraviendran S, Venugopal J, Biswas A, Choolani M, Ramakrishna S, Bongso A, Fong CY. A Nanoscaffold Impregnated With Human Wharton's Jelly Stem Cells or Its Secretions Improves Healing of Wounds. J Cell Biochem 2014; 115:794-803. [DOI: 10.1002/jcb.24723] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2013] [Accepted: 11/18/2013] [Indexed: 01/13/2023]
Affiliation(s)
- Kimberley Tam
- Department of Obstetrics and Gynaecology; Yong Yoo Lin School of Medicine; National University Health System; National University of Singapore; Kent Ridge; Singapore 119228 Singapore
| | - Suganya Cheyyatraviendran
- Department of Obstetrics and Gynaecology; Yong Yoo Lin School of Medicine; National University Health System; National University of Singapore; Kent Ridge; Singapore 119228 Singapore
| | - Jayarama Venugopal
- Department of Mechanical Engineering, Centre for Nanofibers and Nanotechnology; School of Engineering; National University of Singapore; Singapore 117576 Singapore
| | - Arijit Biswas
- Department of Obstetrics and Gynaecology; Yong Yoo Lin School of Medicine; National University Health System; National University of Singapore; Kent Ridge; Singapore 119228 Singapore
| | - Mahesh Choolani
- Department of Obstetrics and Gynaecology; Yong Yoo Lin School of Medicine; National University Health System; National University of Singapore; Kent Ridge; Singapore 119228 Singapore
| | - Seeram Ramakrishna
- Department of Mechanical Engineering, Centre for Nanofibers and Nanotechnology; School of Engineering; National University of Singapore; Singapore 117576 Singapore
| | - Ariff Bongso
- Department of Obstetrics and Gynaecology; Yong Yoo Lin School of Medicine; National University Health System; National University of Singapore; Kent Ridge; Singapore 119228 Singapore
| | - Chui-Yee Fong
- Department of Obstetrics and Gynaecology; Yong Yoo Lin School of Medicine; National University Health System; National University of Singapore; Kent Ridge; Singapore 119228 Singapore
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Schaff UY, Trott KA, Chase S, Tam K, Johns JL, Carlyon JA, Genetos DC, Walker NJ, Simon SI, Borjesson DL. Neutrophils exposed to A. phagocytophilum under shear stress fail to fully activate, polarize, and transmigrate across inflamed endothelium. Am J Physiol Cell Physiol 2010; 299:C87-96. [PMID: 20392928 DOI: 10.1152/ajpcell.00165.2009] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Anaplasma phagocytophilum is an obligate intracellular bacterium that has evolved mechanisms to hijack polymorphonuclear neutrophil (PMN) receptors and signaling pathways to bind, infect, and multiply within the host cell. E-selectin is upregulated during inflammation and is a requisite endothelial receptor that supports PMN capture, rolling, and activation of integrin-mediated arrest. Ligands expressed by PMN that mediate binding to endothelium via E-selectin include sialyl Lewis x (sLe(x))-expressing ligands such as P-selectin glycoprotein ligand-1 (PSGL-1) and other glycolipids and glycoproteins. As A. phagocytophilum is capable of binding to sLe(x)-expressing ligands expressed on PMN, we hypothesized that acute bacterial adhesion to PMN would subsequently attenuate PMN recruitment during inflammation. We assessed the dynamics of PMN recruitment and migration under shear flow in the presence of a wild-type strain of A. phagocytophilum and compared it with a strain of bacteria that binds to PMN independent of PSGL-1. Acute bacterial engagement with PMN resulted in transient PMN arrest and minimal PMN polarization. Although the wild-type pathogen also signaled activation of beta2 integrins and elicited a mild intracellular calcium flux, downstream signals including PMN transmigration and phosphorylation of p38 mitogen-activated protein kinase (MAPK) were inhibited. The mutant strain bound less well to PMN and failed to activate beta2 integrins and induce a calcium flux but did result in decreased PMN arrest and polarization that may have been partially mediated by a suppression of p38 MAPK activation. This model suggests that A. phagocytophilum binding to PMN under shear flow during recruitment to inflamed endothelium interferes with normal tethering via E-selectin and navigational signaling of transendothelial migration.
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Affiliation(s)
- U Y Schaff
- Department of Biomedical Engineering, School of Veterinary Medicine, University of California, Davis, CA 95616, USA
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Tam K, Banwell K, Froiland D, Russell D, Kind K, Thompson J. 120. OXYGEN REGULATED GENE EXPRESSION IN MOUSE CUMULUS CELLS. Reprod Fertil Dev 2009. [DOI: 10.1071/srb09abs120] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Hypoxia inducible factors (HIFs) are heterodimeric transcription factors that mediate the expression of a range of genes in response to low oxygen. Previously we showed that subsequent developmental outcomes were influenced by oxygen levels during in vitro maturation. The aim of the current study was to examine the effects of varying oxygen concentration during in vitro maturation of mouse COCs on expression of HIF target genes in the cumulus cells. I mmature COCs were collected from the ovaries of eCG-stimulated CBAB6F1 females (21 d) and cultured for 17-18 h under 2, 5 or 20% O2. Hyaluronidase-treated and recovered cumulus cells were collected and mRNA extracted for analysis. A microarray approach (Affymetrix 430_2) was used to identify genes in cumulus cells that were differentially expressed under varying oxygen concentrations (2, 5, 10 and 20%). This revealed 218 differentially expressed probes, of which 34 were up-regulated with decreasing oxygen levels. The great majority of these were classified as HIF-regulated genes. Specific analysis from real time RT-PCR of HIF regulated target genes Slc2a1, Ldha, Pgk1, Eno1, Ndrg1, Bnip3 were all significantly up-regulated (by at least 5–fold) when cells were cultured at 2% or 5% oxygen, when compared to 20% oxygen. Hif-1a mRNA decreased when cumulus cells were cultured in 2%, compared to 20% oxygen. This study demonstrates that cumulus cell gene expression is influenced by oxygen concentration, and suggests that these effects are mediated by the HIF transcription factors.
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Tam K, Russell D, Kind K, Thompson JG. Post hCG Follicle Differentiation in the Mouse Is Associated with an Increase in Hypoxia Inducible Factor Activity. Biol Reprod 2008. [DOI: 10.1093/biolreprod/78.s1.127c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Tam K, Russell D, Kind K, Thompson J. 435. Follicle differentiation and luteinisation in the mouse is associated with hypoxia inducible factor activity. Reprod Fertil Dev 2008. [DOI: 10.1071/srb08abs435] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Hypoxia inducible factors (HIF) are transcription factors that mediate the response to hypoxic stress. Under hypoxic conditions, HIF is stabilised, translocates to the nucleus, and binds to the Hypoxia Response Elements (HRE) upstream of numerous target genes involved in angiogenesis and glycolysis, including Vegf, Glut-1 and Ldha. Little is known about the role of HIFs in regulating ovarian function. In rat granulosa cells, FSH stimulates HIF 1α via the PI3K/Akt pathway, demonstrating a role for HIFs during follicular development. In contrast, there is limited information regarding the role of HIFs during corpus luteum formation. In this study we investigated whether HIFs play a role in follicle differentiation and luteinisation. Prepubertal C57Bl6 females were stimulated with eCG (5 IU) followed 46 h later by hCG (5 IU). Mice were sacrificed at 0, 4, 8, 12, 16 and 24 h post hCG and granulosa cells were collected for Western analysis of HIF-1a protein. To investigate HIF activation in the ovary, a transgenic reporter mouse line was developed by lenti-viral incorporation of an HRE (4)-SV40-eGFP construct. Ovaries were collected from mice plugged day 1, 4 and 8 for CL analysis in vivo.A time- dependent increase of HIF 1α protein levels in granulosa cells, maximal around time of ovulation, was observed. Ovaries from cycling HRE-eGFP transgenic mice exhibited no eGFP in primordial, primary or preantral follicles. Upon antrum formation, eGFP was evident in occasional sections in antral follicles but HIF signalling was restricted within the theca. In contrast, corpora lutea on pregnancy day 1, 4 and 8 readily expressed eGFP and eGFP expression increases as luteinisation progresses.These results demonstrate that in vivo HIFs may play a role in folliculogenesis, but this is restricted to theca cells of antral follicles before hCG stimulation. Following hCG, maximal HIF activity is associated with the time of ovulation. In addition, HIF activity is maintained during luteinisation.
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Tam K, Kinsinger N, Ayala P, Qi F, Shi W, Myung N. Real-time monitoring of Streptococcus mutans biofilm formation using a quartz crystal microbalance. Caries Res 2007; 41:474-83. [PMID: 17851235 PMCID: PMC2820325 DOI: 10.1159/000108321] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [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] [Received: 04/19/2006] [Accepted: 05/11/2007] [Indexed: 11/19/2022] Open
Abstract
The ability of Streptococcus mutans, a well-known etiological agent in dental caries, to attach and form a biofilm is an important key to its virulence. The effects of various environmental factors (i.e. sucrose concentration, flow rate and temperature as well as genetic manipulations) on the capability of S. mutans (UA 140) to attach, form and detach were monitored in situ using quartz crystal microbalance. The biofilm growth rate was much slower than that of planktonic growth. Greater availability of sucrose contributed to biofilms with less lag time, lower doubling times and earlier detachment. Flow rate experiments showed that as the shear stress was reduced, the maximum mass accumulated also decreased. However, the detachment process was independent of shear force, perhaps indicative of quorum sensing. Increasing the incubation temperature from 37 to 40 degrees C extended the lag period and inhibited the ability of the biofilm to attach readily. Absence of either the ciaH, luxS, gtfB or gtfC genes also greatly affected the ability of the S. mutans to adhere to a surface in comparison to the wild type. Quartz crystal microbalance results indicate that the gtfC gene possibly has a greater contribution to biofilm attachment than the gtfB gene, that the presence of the luxS gene is critical for attachment and that the ciaH gene primarily affects the initial reversible attachment of the biofilm.
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Affiliation(s)
- K. Tam
- Department of Chemical and Environmental Engineering, University of California-Riverside, Riverside, Calif., Los Angeles, Calif., USA
| | - N. Kinsinger
- Department of Chemical and Environmental Engineering, University of California-Riverside, Riverside, Calif., Los Angeles, Calif., USA
| | - P. Ayala
- Department of Chemical and Environmental Engineering, University of California-Riverside, Riverside, Calif., Los Angeles, Calif., USA
| | - F. Qi
- Department of Oral Biology and Medicine, UCLA School of Dentistry, Los Angeles, Calif., USA
| | - W. Shi
- Department of Oral Biology and Medicine, UCLA School of Dentistry, Los Angeles, Calif., USA
| | - N.V. Myung
- Department of Chemical and Environmental Engineering, University of California-Riverside, Riverside, Calif., Los Angeles, Calif., USA
- *Dr. N.V. Myung, Department of Chemical and Environmental Engineering, University of California, Bourns Hall, Riverside, CA 92521 (USA), Tel. +1 951 827 7710, Fax +1 951 827 5696, E-Mail
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Abstract
STUDY OBJECTIVES Obstructive sleep apnea (OSA) is characterized by repeated episodes of upper-airway obstruction during sleep leading to significant hypercapnic hypoxic conditions. These conditions are associated with increased levels of proinflammatory cytokines (including interleukin [IL]-6, tumor necrosis factor [TNF]-alpha, and C-reactive protein [CRP]) and subsequent increased cardiovascular risk. It is unclear whether hypercapnic hypoxia itself causes inflammatory perturbations. DESIGN We evaluated circulating IL-6, TNF- a and CRP in a piglet model of infant OSA, following exposure to acute intermittent hypercapnic hypoxia (IHH). Study groups comprised of treatment (n = 8) and control (n = 8) groups. Treatment was two 90-minute sessions of IHH with arterial blood sampled before and after each IHH session. MEASUREMENTS AND RESULTS IL-6, TNF-alpha and CRP levels were measured before and after IHH treatment sessions. Results showed an increase in IL-6 following the first session of IHH that was neither sustained, nor repeated, during a subsequent exposure. Using mixed-modelling, TNF-alpha changed between time points and groups. There were no changes in CRP over the duration of the study. CONCLUSION These results suggest that acute hypoxia causes a transient increase in IL-6 levels and has implications for the pathogenesis of increased cardiovascular disease in OSA, especially in childhood.
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Affiliation(s)
| | - Melanie Wong
- The Children's Hospital at Westmead, Sydney, NSW, Australia
| | - Kimberley Tam
- Department of Medicine, The University of Sydney, NSW, Australia
| | - Leyla Aouad
- Department of Medicine, The University of Sydney, NSW, Australia
| | - Karen A. Waters
- The Children's Hospital at Westmead, Sydney, NSW, Australia
- Department of Medicine, The University of Sydney, NSW, Australia
- Address correspondence to: Dr. Karen A. Waters,
Department of Medicine, Room 206, Blackburn Building, DO6, University of Sydney, NSW 2006, Australia61 2 9351 516561 2 9550 3851
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Kreth J, Hagerman E, Tam K, Merritt J, Wong DTW, Wu BM, Myung NV, Shi W, Qi F. Quantitative analyses of Streptococcus mutans biofilms with quartz crystal microbalance, microjet impingement and confocal microscopy. ACTA ACUST UNITED AC 2005; 1:277-284. [PMID: 16429589 PMCID: PMC1307168 DOI: 10.1017/s1479050504001516] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Microbial biofilm formation can be influenced by many physiological and genetic factors. The conventional microtiter plate assay provides useful but limited information about biofilm formation. With the fast expansion of the biofilm research field, there are urgent needs for more informative techniques to quantify the major parameters of a biofilm, such as adhesive strength and total biomass. It would be even more ideal if these measurements could be conducted in a real-time, non-invasive manner. In this study, we used quartz crystal microbalance (QCM) and microjet impingement (MJI) to measure total biomass and adhesive strength, respectively, of S. mutans biofilms formed under different sucrose concentrations. In conjunction with confocal laser scanning microscopy (CLSM) and the COMSTAT software, we show that sucrose concentration affects the biofilm strength, total biomass, and architecture in both qualitative and quantitative manners. Our data correlate well with previous observations about the effect of sucrose on the adherence of S. mutans to the tooth surface, and demonstrate that QCM is a useful tool for studying the kinetics of biofilm formation in real time and that MJI is a sensitive, easy-to-use device to measure the adhesive strength of a biofilm.
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Affiliation(s)
- J. Kreth
- Department of Oral Biology and Medicine, UCLA School of Dentistry, Los Angeles, CA 90095, USA
| | - E. Hagerman
- Department of Bioengineering, UCLA School of Engineering and Applied Sciences, Los Angeles, CA 90095, USA
| | - K. Tam
- Department of Chemical and Environmental Engineering. University of California, Riverside, CA 92521, USA
| | - J. Merritt
- UCLA Molecular Biology Institute, Los Angeles, CA 90025, USA
| | - D. T. W. Wong
- Department of Oral Biology and Medicine, UCLA School of Dentistry, Los Angeles, CA 90095, USA
| | - B. M. Wu
- Department of Bioengineering, UCLA School of Engineering and Applied Sciences, Los Angeles, CA 90095, USA
- Department of Materials Science and Engineering, UCLA School of Engineering and Applied Sciences, Los Angeles, CA 90095, USA
| | - N. V. Myung
- Department of Chemical and Environmental Engineering. University of California, Riverside, CA 92521, USA
| | - W. Shi
- Department of Oral Biology and Medicine, UCLA School of Dentistry, Los Angeles, CA 90095, USA
- UCLA Molecular Biology Institute, Los Angeles, CA 90025, USA
| | - F. Qi
- Department of Oral Biology and Medicine, UCLA School of Dentistry, Los Angeles, CA 90095, USA
- * Corresponding author: Dr F. Qi, Department of Oral Biology and Medicine, UCLA School of Dentistry, PO Box 951668, Los Angeles, CA 90095-1668, USA, T 1 310 825-0203, F 1 310 794-7109, E
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Castro C, Tharmaratnam U, Tam K, Brockhurst N, Tureanu L, Windrim R, Mowbray M. PATIENT CONTROLLED ANALGESIA USING FENTANYL FOR SECOND TRIMESTER LABOR ANALGESIA. VARYING BOLUS DOSE AND LOCKOUT INTERVAL. Anesthesiology 2002. [DOI: 10.1097/00000542-200204001-00059] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Affiliation(s)
- C. Castro
- Anesthesia, Mount Sinai Hospital, Toronto, ON, Canada
| | | | - K. Tam
- Nursing, Mount Sinai Hospital, Toronto, ON, Canada
| | | | - L. Tureanu
- Anesthesia, Mount Sinai Hospital, Toronto, ON, Canada
| | - R. Windrim
- OB/GYN, Mount Sinai Hospital, Toronto, ON, Canada
| | - M. Mowbray
- Nursing, Mount Sinai Hospital, Toronto, ON, Canada
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Ng JS, Fan DS, Young AL, Yip NK, Tam K, Kwok AK, Lam DS. Ocular hypertensive response to topical dexamethasone in children: a dose-dependent phenomenon. Ophthalmology 2000; 107:2097-100. [PMID: 11054340 DOI: 10.1016/s0161-6420(00)00357-2] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.6] [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: 11/21/2022] Open
Abstract
OBJECTIVE To investigate the ocular-hypertensive response to different dosages of topical dexamethasone eye drops in Chinese children. DESIGN Prospective, randomized clinical trial. PARTICIPANTS Thirty-one consecutive children undergoing bilateral strabismus surgery. INTERVENTION Topical dexamethasone (0.1%) was administered to children undergoing bilateral strabismus surgery. They were all less than 10 years of age. One eye was randomized to receive a regimen of four times daily, and another received a twice daily regimen. Intraocular pressure (IOP) was serially measured in the postoperative period for 4 weeks or more. Topical steroids were discontinued if IOP was 30 mmHg or more. MAIN OUTCOME MEASURES Intraocular pressure was measured on the day before the surgery, on postoperative days 1, 3, 5, 8, 12, 15, 22, 29, and 2 weeks thereafter until the IOP reached preoperative levels. Peak IOP, IOP net increase, and time to reach an IOP more than 20 mmHg in the two study groups were analyzed. RESULTS A total of 31 patients (20 male, 11 female) were examined. The mean age was 5.8 +/- 2.0 years (range, 2-10 years). Preoperative IOP in groups treated twice daily and four times daily were similar. After topical dexamethasone treatment, both groups showed a significant rise in peak IOP compared with preoperative values (twice daily, 25.2 +/- 6.8 mmHg vs. 14.3 +/- 2.4 mmHg, P < 0.001; four times daily, 28.7 +/- 6.9 mmHg vs. 14.3 +/- 2.9 mmHg, P < 0.001). The peak IOP was significantly higher in the four times daily group (P < 0.001), as was the net increase in IOP (twice daily, 10.9 +/- 5.8 mmHg vs. four times daily, 14.5 +/- 6.4 mmHg; P < 0.001). There was no difference in time for both groups to achieve the peak IOP, but the time to exceed its upper normal value (20 mmHg) was shorter in the four times daily group (twice daily, 12.3 +/- 9.1 days vs. four times daily, 10.0 +/- 7.4 days; P < 0.05). CONCLUSIONS In children treated with topical dexamethasone, ocular hypertension occurs in a dose-dependent manner. Children in the four times daily group had a quicker onset and more severe ocular hypertensive response than the twice daily group. Nevertheless, even the twice daily regimen produced significant IOP rise, suggesting that dexamethasone use in children should be avoided if possible, and it would be desirable to monitor the IOP twice weekly when it is administered to children.
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Affiliation(s)
- J S Ng
- Department of Ophthalmology, Alice Ho Miu Ling Nethersole Hospital, Tai Po, New Territories, Hong Kong
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Bowen KA, Tam K, Colombini M. Evidence for titratable gating charges controlling the voltage dependence of the outer mitochondrial membrane channel, VDAC. J Membr Biol 1985; 86:51-9. [PMID: 2413210 DOI: 10.1007/bf01871610] [Citation(s) in RCA: 60] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
A voltage-dependent anion-selective channel, VDAC, is found in outer mitochondrial membranes. VDAC's conductance is known to decrease as the transmembrane voltage is increased in either the positive or negative direction. Charged groups on the channel may be responsible for this voltage dependence by allowing the channel to respond to an applied electric field. If so, then neutralization of these charges would eliminate the voltage dependence. Channels in planar lipid bilayers which behaved normally at pH 6 lost much of their voltage dependence at high pH. Raising the pH reduced the steepness of the voltage dependence and raised the voltage needed to close half the channels. In contrast, the energy difference between the open and closed state in the absence of a field was changed very little by the elevated pH. The groups being titrated had an apparent pK of 10.6. From the pK and chemical modification, lysine epsilon amino groups are the most likely candidates responsible for VDAC's ability to respond to an applied electric field.
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