Publications by authors named "Abdul Momen"

42 Publications

Genotype-phenotype correlation of β-lactamase-producing uropathogenic Escherichia coli (UPEC) strains from Bangladesh.

Sci Rep 2020 09 3;10(1):14549. Epub 2020 Sep 3.

Maryland Pathogen Research Institute, University of Maryland, College Park, MD, USA.

Escherichia coli is a pathogen commonly encountered in clinical laboratories, and is capable of causing a variety of diseases, both within the intestinal tract (intestinal pathogenic strains) and outside (extraintestinal pathogenic E. coli, or ExPEC). It is associated with urinary tract infections (UTIs), one of the most common infectious diseases in the world. This report represents the first comparative analysis of the draft genome sequences of 11 uropathogenic E. coli (UPEC) strains isolated from two tertiary hospitals located in Dhaka and Sylhet, Bangladesh, and is focused on comparing their genomic characteristics to each other and to other available UPEC strains. Multilocus sequence typing (MLST) confirmed the strains belong to ST59, ST131, ST219, ST361, ST410, ST448 and ST4204, with one of the isolates classified as a previously undocumented ST. De novo identification of the antibiotic resistance genes bla, bla, bla and bla was determined, and phenotypic-genotypic analysis of virulence revealed significant heterogeneity within UPEC phylogroups.
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http://dx.doi.org/10.1038/s41598-020-71213-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7471317PMC
September 2020

Anaesthesia care providers employed in humanitarian settings by Médecins Sans Frontières: a retrospective observational study of 173 084 surgical cases over 10 years.

BMJ Open 2020 03 4;10(3):e034891. Epub 2020 Mar 4.

Health Services Unit, KEMRI-Wellcome Trust Research Programme, Nairobi, Kenya.

Objective: To describe the extent to which different categories of anaesthesia provider are used in humanitarian surgical projects and to explore the volume and nature of their surgical workload.

Design: Descriptive analysis using 10 years (2008-2017) of routine case-level data linked with routine programme-level data from surgical projects run exclusively by Médecins Sans Frontières-Operational Centre Brussels (MSF-OCB).

Setting: Projects were in contexts of natural disaster (ND, entire expatriate team deployed by MSF-OCB), active conflict (AC) and stable healthcare gaps (HG). In AC and HG settings, MSF-OCB support pre-existing local facilities. Hospital facilities ranged from basic health centres with surgical capabilities to tertiary referral centres.

Participants: The full dataset included 178 814 surgical cases. These were categorised by most senior anaesthetic provider for the project, according to qualification: specialist physician anaesthesiologists, qualified nurse anaesthetists and uncertified anaesthesia providers.

Primary Outcome Measure: Volume and nature of surgical workload of different anaesthesia providers.

Results: Full routine data were available for 173 084 cases (96.8%): 2518 in ND, 42 225 in AC, 126 936 in HG. Anaesthesia was predominantly led by physician anaesthesiologists (100% in ND, 66% in AC and HG), then nurse anaesthetists (19% in AC and HG) or uncertified anaesthesia providers (15% in AC and HG). Across all settings and provider groups, patients were mostly healthy young adults (median age range 24-27 years), with predominantly females in HG contexts, and males in AC contexts. Overall intra-operative mortality was 0.2%.

Conclusion: Our findings contribute to existing knowledge of the nature of anaesthetic provision in humanitarian settings, while demonstrating the value of high-quality, routine data collection at scale in this sector. Further evaluation of perioperative outcomes associated with different models of humanitarian anaesthetic provision is required.
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http://dx.doi.org/10.1136/bmjopen-2019-034891DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7059447PMC
March 2020

Whole genome sequencing provides genomic insights into three Morganella morganii strains isolated from bovine rectal swabs in Dhaka, Bangladesh.

FEMS Microbiol Lett 2020 03;367(6)

NSU Genome Research Institute (NGRI), North South University, Dhaka, Bangladesh.

Morganella morganii, a gram negative, facultative anaerobic bacterium belonging to the Proteeae tribe of the Morganellaceae family, is an unusual opportunistic pathogen mainly responsible for nosocomial and urinary tract infections. While cattle have long been established as a source of a few zoonotic pathogens, no such data has been recorded for M. morganii despite its ubiquitous presence in nature and a number of animal hosts. In this study, draft genomes were produced of three M. morganii isolates from Bangladeshi cattle. The three isolates, named B2, B3 and B5, possessed an average genome size of 3.9 Mp, a GC% of ∼51% and pan and core genomes of 4637 and 3812 genes, respectively. All strains were bearers of the qnrD1 carrying plasmid Col3M and possessed roughly similar virulence profiles and prophage regions. The strains also carried genes that were unique when compared with other publicly available M. morganii genomes. Many of these genes belonged to metabolic pathways associated with adaptation to environmental stresses and were predicted in silico to be borne in genomic islands. The findings of this study expand on the current understanding of M. morganii''s genomic nature and its adaptation in cattle.
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http://dx.doi.org/10.1093/femsle/fnaa043DOI Listing
March 2020

Cardioprotective GLP-1 metabolite prevents ischemic cardiac injury by inhibiting mitochondrial trifunctional protein-α.

J Clin Invest 2020 03;130(3):1392-1404

Ted Rogers Centre for Heart Research, University of Toronto, Toronto, Ontario, Canada.

Mechanisms mediating the cardioprotective actions of glucagon-like peptide 1 (GLP-1) were unknown. Here, we show in both ex vivo and in vivo models of ischemic injury that treatment with GLP-1(28-36), a neutral endopeptidase-generated (NEP-generated) metabolite of GLP-1, was as cardioprotective as GLP-1 and was abolished by scrambling its amino acid sequence. GLP-1(28-36) enters human coronary artery endothelial cells (caECs) through macropinocytosis and acts directly on mouse and human coronary artery smooth muscle cells (caSMCs) and caECs, resulting in soluble adenylyl cyclase Adcy10-dependent (sAC-dependent) increases in cAMP, activation of protein kinase A, and cytoprotection from oxidative injury. GLP-1(28-36) modulates sAC by increasing intracellular ATP levels, with accompanying cAMP accumulation lost in sAC-/- cells. We identify mitochondrial trifunctional protein-α (MTPα) as a binding partner of GLP-1(28-36) and demonstrate that the ability of GLP-1(28-36) to shift substrate utilization from oxygen-consuming fatty acid metabolism toward oxygen-sparing glycolysis and glucose oxidation and to increase cAMP levels is dependent on MTPα. NEP inhibition with sacubitril blunted the ability of GLP-1 to increase cAMP levels in coronary vascular cells in vitro. GLP-1(28-36) is a small peptide that targets novel molecular (MTPα and sAC) and cellular (caSMC and caEC) mechanisms in myocardial ischemic injury.
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http://dx.doi.org/10.1172/JCI99934DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7269572PMC
March 2020

CFTR Therapeutics Normalize Cerebral Perfusion Deficits in Mouse Models of Heart Failure and Subarachnoid Hemorrhage.

JACC Basic Transl Sci 2019 Dec 27;4(8):940-958. Epub 2019 Nov 27.

Department of Physiology, University of Toronto, Toronto, Ontario, Canada.

Heart failure (HF) and subarachnoid hemorrhage (SAH) chronically reduce cerebral perfusion, which negatively affects clinical outcome. This work demonstrates a strong relationship between cerebral artery cystic fibrosis transmembrane conductance regulator (CFTR) expression and altered cerebrovascular reactivity in HF and SAH. In HF and SAH, CFTR corrector compounds (C18 or lumacaftor) normalize pathological alterations in cerebral artery CFTR expression, vascular reactivity, and cerebral perfusion, without affecting systemic hemodynamic parameters. This normalization correlates with reduced neuronal injury. Therefore, CFTR therapeutics have emerged as valuable clinical tools to manage cerebrovascular dysfunction, impaired cerebral perfusion, and neuronal injury.
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http://dx.doi.org/10.1016/j.jacbts.2019.07.004DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6939007PMC
December 2019

Publisher Correction: Self-renewing resident cardiac macrophages limit adverse remodeling following myocardial infarction.

Nat Immunol 2019 May;20(5):664

Toronto General Hospital Research Institute, University Health Network (UHN), Toronto, Canada.

In the version of this article initially published, the equal contribution of the third author was omitted. The footnote links for that author should be "Sara Nejat" and the correct statement is as follows: "These authors contributed equally: Sarah A. Dick, Jillian A. Macklin, Sara Nejat." The error has been corrected in the HTML and PDF versions of the article.
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http://dx.doi.org/10.1038/s41590-019-0363-8DOI Listing
May 2019

B-Cell Deficiency Lowers Blood Pressure in Mice.

Hypertension 2019 03;73(3):561-570

From the Toronto General Hospital Research Institute, University Health Network, Canada (L.S.D., E.A.S., A.M., T.A., F.B., M.H.).

The proto-oncogene c-myb (and corresponding nuclear transcription factor, c-Myb) regulates the proliferation and differentiation of hematologic and vascular smooth muscle cells; however, the role of c-Myb in blood pressure regulation is unknown. Here, we show that mice homozygous for a hypomorphic c-myb allele ( c-myb ) conferring reduced c-Myb activity manifest reduced peripheral blood and kidney B220 B-cells and have decreased systolic (104±2 versus 120±1 mm Hg; P<0.0001) and diastolic blood pressure (71±2 versus 83±1 mm Hg; P<0.0001) compared with WT (wild type) mice. Additionally, c-myb mice had lower susceptibility to deoxycorticosterone acetate-salt experimental hypertension. Although cardiac (echocardiography) and resistance artery (perfusion myography) functions were normal, metabolic cage studies revealed that c-myb mice had increased 24-hour urine output and sodium excretion versus WT. Reconstitution of WT mice with c-myb bone marrow transplant and chimeric bone marrow transplant using mice lacking B-cells ( J T; h/h>WT and h/h:J T>WT, respectively) decreased blood pressure and increased 24-hour urine output compared with controls ( WT>WT; WT:J T>WT). J T mice also had decreased systolic (103±2 versus 115±1 mm Hg; P<0.0001) and diastolic blood pressure (71±2 versus 79±1; P<0.01) and increased 24-hour urine output versus WT. Real-time quantitative reverse transcription polymerase chain reaction of kidney medulla revealed reduced VR (vasopressin receptor 2) expression in c-myb and J T mice. These data implicate B-cells in the regulation of VR and its associated effects on salt and water handling and blood pressure homeostasis.
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http://dx.doi.org/10.1161/HYPERTENSIONAHA.118.11828DOI Listing
March 2019

Self-renewing resident cardiac macrophages limit adverse remodeling following myocardial infarction.

Nat Immunol 2019 01 11;20(1):29-39. Epub 2018 Dec 11.

Toronto General Hospital Research Institute, University Health Network (UHN), Toronto, Canada.

Macrophages promote both injury and repair after myocardial infarction, but discriminating functions within mixed populations remains challenging. Here we used fate mapping, parabiosis and single-cell transcriptomics to demonstrate that at steady state, TIMD4LYVE1MHC-IICCR2 resident cardiac macrophages self-renew with negligible blood monocyte input. Monocytes partially replaced resident TIMD4LYVE1MHC-IICCR2 macrophages and fully replaced TIMD4LYVE1MHC-IICCR2 macrophages, revealing a hierarchy of monocyte contribution to functionally distinct macrophage subsets. Ischemic injury reduced TIMD4 and TIMD4 resident macrophage abundance, whereas CCR2 monocyte-derived macrophages adopted multiple cell fates within infarcted tissue, including those nearly indistinguishable from resident macrophages. Recruited macrophages did not express TIMD4, highlighting the ability of TIMD4 to track a subset of resident macrophages in the absence of fate mapping. Despite this similarity, inducible depletion of resident macrophages using a Cx3cr1-based system led to impaired cardiac function and promoted adverse remodeling primarily within the peri-infarct zone, revealing a nonredundant, cardioprotective role of resident cardiac macrophages.
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http://dx.doi.org/10.1038/s41590-018-0272-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6565365PMC
January 2019

Cardiac-specific inducible overexpression of human plasma membrane Ca ATPase 4b is cardioprotective and improves survival in mice following ischemic injury.

Clin Sci (Lond) 2018 03 26;132(6):641-654. Epub 2018 Mar 26.

Toronto General Hospital Research Institute, University Health Network, Toronto, ON M5G-2C4, Canada

Heart failure (HF) is associated with reduced expression of plasma membrane Ca-ATPase 4 (PMCA4). Cardiac-specific overexpression of human PMCA4b in mice inhibited nNOS activity and reduced cardiac hypertrophy by inhibiting calcineurin. Here we examine temporally regulated cardiac-specific overexpression of hPMCA4b in mouse models of myocardial ischemia reperfusion injury (IRI) , and HF following experimental myocardial infarction (MI) Doxycycline-regulated cardiomyocyte-specific overexpression and activity of hPMCA4b produced adaptive changes in expression levels of Ca-regulatory genes, and induced hypertrophy without significant differences in Ca transients or diastolic Ca concentrations. Total cardiac NOS and nNOS-specific activities were reduced in mice with cardiac overexpression of hPMCA4b while nNOS, eNOS and iNOS protein levels did not differ. hMPCA4b-overexpressing mice also exhibited elevated systolic blood pressure vs. controls, with increased contractility and lusitropy In isolated hearts undergoing IRI, hPMCA4b overexpression was cardioprotective. NO donor-treated hearts overexpressing hPMCA4b showed reduced LVDP and larger infarct size versus vehicle-treated hearts undergoing IRI, demonstrating that the cardioprotective benefits of hPMCA4b-repressed nNOS are lost by restoring NO availability. Finally, both pre-existing and post-MI induction of hPMCA4b overexpression reduced infarct expansion and improved survival from HF. Cardiac PMCA4b regulates nNOS activity, cardiac mass and contractility, such that PMCA4b overexpression preserves cardiac function following IRI, heightens cardiac performance and limits infarct progression, cardiac hypertrophy and HF, even when induced late post-MI. These data identify PMCA4b as a novel therapeutic target for IRI and HF.
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http://dx.doi.org/10.1042/CS20171337DOI Listing
March 2018

A CD103 Conventional Dendritic Cell Surveillance System Prevents Development of Overt Heart Failure during Subclinical Viral Myocarditis.

Immunity 2017 11;47(5):974-989.e8

Toronto General Hospital Research Institute, University Health Network (UHN), Toronto ON, M5G 1L7, Canada; Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto ON, M5S 1A1, Canada; Department of Immunology, University of Toronto, Toronto ON, M5S 1A1, Canada; Peter Munk Cardiac Centre, Toronto ON, M5G 1L7, Canada; Ted Rogers Centre for Heart Research, Toronto ON, M5G 1L7, Canada. Electronic address:

Innate and adaptive immune cells modulate heart failure pathogenesis during viral myocarditis, yet their identities and functions remain poorly defined. We utilized a combination of genetic fate mapping, parabiotic, transcriptional, and functional analyses and demonstrated that the heart contained two major conventional dendritic cell (cDC) subsets, CD103 and CD11b, which differentially relied on local proliferation and precursor recruitment to maintain their tissue residency. Following viral infection of the myocardium, cDCs accumulated in the heart coincident with monocyte infiltration and loss of resident reparative embryonic-derived cardiac macrophages. cDC depletion abrogated antigen-specific CD8 T cell proliferative expansion, transforming subclinical cardiac injury to overt heart failure. These effects were mediated by CD103 cDCs, which are dependent on the transcription factor BATF3 for their development. Collectively, our findings identified resident cardiac cDC subsets, defined their origins, and revealed an essential role for CD103 cDCs in antigen-specific T cell responses during subclinical viral myocarditis.
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http://dx.doi.org/10.1016/j.immuni.2017.10.011DOI Listing
November 2017

HDL protects against doxorubicin-induced cardiotoxicity in a scavenger receptor class B type 1-, PI3K-, and Akt-dependent manner.

Am J Physiol Heart Circ Physiol 2018 01 6;314(1):H31-H44. Epub 2017 Oct 6.

Medical Sciences Graduate Program, McMaster University , Hamilton, Ontario , Canada.

Doxorubicin is a widely used chemotherapeutic with deleterious cardiotoxic side effects. HDL has been shown to protect cardiomyocytes in vitro against doxorubicin-induced apoptosis. Scavenger receptor class B type 1 (SR-B1), a high-affinity HDL receptor, mediates cytoprotective signaling by HDL through Akt. Here, we assessed whether increased HDL levels protect against doxorubicin-induced cardiotoxicity in vivo and in cardiomyocytes in culture and explored the intracellular signaling mechanisms involved, particularly the role of SR-B1. Transgenic mice with increased HDL levels through overexpression of human apolipoprotein A1 (apoA1) and wild-type mice (apoA1) with normal HDL levels were treated repeatedly with doxorubicin. After treatment, apoA1 mice displayed cardiac dysfunction, as evidenced by reduced left ventricular end-systolic pressure and +dP/d t, and histological analysis revealed cardiomyocyte atrophy and increased cardiomyocyte apoptosis after doxorubicin treatment. In contrast, apoA1 mice were protected against doxorubicin-induced cardiac dysfunction and cardiomyocyte atrophy and apoptosis. When SR-B1 was knocked out, however, overexpression of apoA1 did not protect against doxorubicin-induced cardiotoxicity. Using primary neonatal mouse cardiomyocytes and human immortalized ventricular cardiomyocytes in combination with genetic knockout, inhibitors, or siRNA-mediated knockdown, we demonstrated that SR-B1 is required for HDL-mediated protection of cardiomyocytes against doxorubicin-induced apoptosis in vitro via a pathway involving phosphatidylinositol 3-kinase and Akt1/2. Our findings provide proof of concept that raising apoA1 to supraphysiological levels can dramatically protect against doxorubicin-induced cardiotoxicity via a pathway that is mediated by SR-B1 and involves Akt1/2 activation in cardiomyocytes. NEW & NOTEWORTHY We have identified an important role for the scavenger receptor class B type 1 in facilitating high-density lipoprotein-mediated protection of cardiomyocytes against stress-induced apoptosis and shown that increasing plasma high-density lipoprotein protects against the deleterious side effects of the chemotherapeutic and cardiotoxic drug doxorubicin.
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http://dx.doi.org/10.1152/ajpheart.00521.2016DOI Listing
January 2018

Flexible shape-memory scaffold for minimally invasive delivery of functional tissues.

Nat Mater 2017 10 14;16(10):1038-1046. Epub 2017 Aug 14.

Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, Ontario M5S 3E5, Canada.

Despite great progress in engineering functional tissues for organ repair, including the heart, an invasive surgical approach is still required for their implantation. Here, we designed an elastic and microfabricated scaffold using a biodegradable polymer (poly(octamethylene maleate (anhydride) citrate)) for functional tissue delivery via injection. The scaffold's shape memory was due to the microfabricated lattice design. Scaffolds and cardiac patches (1 cm × 1 cm) were delivered through an orifice as small as 1 mm, recovering their initial shape following injection without affecting cardiomyocyte viability and function. In a subcutaneous syngeneic rat model, injection of cardiac patches was equivalent to open surgery when comparing vascularization, macrophage recruitment and cell survival. The patches significantly improved cardiac function following myocardial infarction in a rat, compared with the untreated controls. Successful minimally invasive delivery of human cell-derived patches to the epicardium, aorta and liver in a large-animal (porcine) model was achieved.
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http://dx.doi.org/10.1038/nmat4956DOI Listing
October 2017

Long-term audit of the use of fresh frozen plasma in a university hospital.

J Taibah Univ Med Sci 2017 Oct 9;12(5):437-444. Epub 2017 Jun 9.

Department of Statistics, College of Sciences and Health Professions, King Saud bin Abdulaziz University for Health Sciences, Riyadh, KSA.

Objectives: There is universal concern about the inappropriate use of fresh frozen plasma (FFP). This study aimed to determine the extent of the inappropriate use of FFP at a university hospital in KSA.

Methods: Medical records on the annual use of FFP were analysed from 1986 to 2007. Then, the results of the coagulation screening tests were extracted from the medical records of 531 consecutive patients in various departments of the hospital.

Results: As many as 68,480 FFP units were used during the 22 year study period. Consumption increased and then plateaued in 1995, but dropped dramatically by 30.9% and reached its lowest level in 2000. There was also a concomitant and overlapping drop in both FFP usage and the hospital mortality rate per patient admission. One-thousand-six-hundred-twenty FFP units were issued for 531 patients. Coagulation testing, before and after infusion, was adopted in almost all patients in the Department of Obstetrics and Gynaecology, in 90% of patients in the Department of Surgery and in approximately 70% of patients in other departments.

Conclusions: Significant inappropriate use of FFP at our institute has been made evident by examining the remarkable drop in use following the universal "HIV scare" of the early 1990s. The resulting drop in the hospital mortality rate, accompanying the simultaneous drop in FFP use, reflects the benefits of resorting to the use of less blood therapy. Coagulation testing was used to a satisfactory extent. Transfusion audits and educational programs could result a better use of FFP.
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http://dx.doi.org/10.1016/j.jtumed.2017.04.001DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6695031PMC
October 2017

Tumor Necrosis Factor/Sphingosine-1-Phosphate Signaling Augments Resistance Artery Myogenic Tone in Diabetes.

Diabetes 2016 07 5;65(7):1916-28. Epub 2016 Apr 5.

Department of Physiology, University of Toronto, Toronto, Ontario, Canada Toronto Centre for Microvascular Medicine, University of Toronto at the Li Ka Shing Knowledge Institute, St. Michael's Hospital, Toronto, Ontario, Canada Heart and Stroke/Richard Lewar Centre of Excellence for Cardiovascular Research, University of Toronto, Toronto, Ontario, Canada Keenan Research Centre at the Li Ka Shing Knowledge Institute, St. Michael's Hospital, Toronto, Ontario, Canada

Diabetes strongly associates with microvascular complications that ultimately promote multiorgan failure. Altered myogenic responsiveness compromises tissue perfusion, aggravates hypertension, and sets the stage for later permanent structural changes to the microcirculation. We demonstrate that skeletal muscle resistance arteries isolated from patients with diabetes have augmented myogenic tone, despite reasonable blood glucose control. To understand the mechanisms, we titrated a standard diabetes mouse model (high-fat diet plus streptozotocin [HFD/STZ]) to induce a mild increase in blood glucose levels. HFD/STZ treatment induced a progressive myogenic tone augmentation in mesenteric and olfactory cerebral arteries; neither HFD nor STZ alone had an effect on blood glucose or resistance artery myogenic tone. Using gene deletion models that eliminate tumor necrosis factor (TNF) or sphingosine kinase 1, we demonstrate that vascular smooth muscle cell TNF drives the elevation of myogenic tone via enhanced sphingosine-1-phosphate (S1P) signaling. Therapeutically antagonizing TNF (etanercept) or S1P (JTE013) signaling corrects this defect. Our investigation concludes that vascular smooth muscle cell TNF augments resistance artery myogenic vasoconstriction in a diabetes model that induces a small elevation of blood glucose. Our data demonstrate that microvascular reactivity is an early disease marker and advocate establishing therapies that strategically target the microcirculation.
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http://dx.doi.org/10.2337/db15-1450DOI Listing
July 2016

c-Myb Regulates Proliferation and Differentiation of Adventitial Sca1+ Vascular Smooth Muscle Cell Progenitors by Transactivation of Myocardin.

Arterioscler Thromb Vasc Biol 2016 07 12;36(7):1367-76. Epub 2016 May 12.

From the Toronto General Research Institute, University Health Network, Toronto, Ontario, Canada (E.A.S., M.C., R.B., A.M., O.E.-M., C.S.R., M.H.); and Heart and Stroke Richard Lewar Centre of Excellence, Ted Rogers Centre for Heart Research, McEwen Centre for Regenerative Medicine, and Peter Munk Cardiac Centre (E.A.S., M.C., R.B., C.S.R., M.H.), Department of Laboratory Medicine and Pathobiology (E.A.S., R.B., C.S.R., M.H.), Department of Immunology (C.C.L., C.S.R.), and Department of Medicine (M.C., M.H.), University of Toronto, Ontario, Canada.

Objective: Vascular smooth muscle cells (VSMCs) are believed to dedifferentiate and proliferate in response to vessel injury. Recently, adventitial progenitor cells were implicated as a source of VSMCs involved in vessel remodeling. c-Myb is a transcription factor known to regulate VSMC proliferation in vivo and differentiation of VSMCs from mouse embryonic stem cell-derived progenitors in vitro. However, the role of c-Myb in regulating specific adult vascular progenitor cell populations was not known. Our objective was to examine the role of c-Myb in the proliferation and differentiation of Sca1(+) adventitial VSMC progenitor cells.

Approach And Results: Using mice with wild-type or hypomorphic c-myb (c-myb(h/h)), BrdU (bromodeoxyuridine) uptake and flow cytometry revealed defective proliferation of Sca1(+) adventitial VSMC progenitor cells at 8, 14, and 28 days post carotid artery denudation injury in c-myb(h/h) arteries. c-myb(h/h) cKit(+)CD34(-)Flk1(-)Sca1(+)CD45(-)Lin(-) cells failed to proliferate, suggesting that c-myb regulates the activation of specific Sca1(+) progenitor cells in vivo and in vitro. Although expression levels of transforming growth factor-β1 did not vary between wild-type and c-myb(h/h) carotid arteries, in vitro differentiation of c-myb(h/h) Sca1(+) cells manifested defective transforming growth factor-β1-induced VSMC differentiation. This is mediated by reduced transcriptional activation of myocardin because chromatin immunoprecipitation revealed c-Myb binding to the myocardin promoter only during differentiation of Sca1(+) cells, myocardin promoter mutagenesis identified 2 specific c-Myb-responsive binding sites, and adenovirus-mediated expression of myocardin rescued the phenotype of c-myb(h/h) progenitors.

Conclusions: These data support a role for c-Myb in the regulation of VSMC progenitor cells and provide novel insight into how c-myb regulates VSMC differentiation through myocardin.
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http://dx.doi.org/10.1161/ATVBAHA.115.307116DOI Listing
July 2016

Biodegradable scaffold with built-in vasculature for organ-on-a-chip engineering and direct surgical anastomosis.

Nat Mater 2016 06 7;15(6):669-78. Epub 2016 Mar 7.

Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, Ontario M5S 3E5, Canada.

We report the fabrication of a scaffold (hereafter referred to as AngioChip) that supports the assembly of parenchymal cells on a mechanically tunable matrix surrounding a perfusable, branched, three-dimensional microchannel network coated with endothelial cells. The design of AngioChip decouples the material choices for the engineered vessel network and for cell seeding in the parenchyma, enabling extensive remodelling while maintaining an open-vessel lumen. The incorporation of nanopores and micro-holes in the vessel walls enhances permeability, and permits intercellular crosstalk and extravasation of monocytes and endothelial cells on biomolecular stimulation. We also show that vascularized hepatic tissues and cardiac tissues engineered by using AngioChips process clinically relevant drugs delivered through the vasculature, and that millimetre-thick cardiac tissues can be engineered in a scalable manner. Moreover, we demonstrate that AngioChip cardiac tissues implanted with direct surgical anastomosis to the femoral vessels of rat hindlimbs establish immediate blood perfusion.
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http://dx.doi.org/10.1038/nmat4570DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4879054PMC
June 2016

The Levels of Tissue Factor Pathway Inhibitor in Sepsis Patients Receiving Prophylactic Enoxaparin.

Turk J Haematol 2016 Jun 6;33(2):112-8. Epub 2015 Aug 6.

King Saud University College of Medicine, King Khalid University Hospital, Department of Critical Care, Riyadh, Saudi Arabia, Phone : +96611-4692253, E-mail :

Objective: Sepsis syndrome is usually accompanied by activation of blood coagulation mechanisms. Earlier studies found deficiencies of the 3 main natural anticoagulants, antithrombin, protein C, and protein S. However, none of these inhibitors block tissue factor, the prime trigger of coagulation during sepsis that is controlled specifically by the tissue factor pathway inhibitor (TFPI). The aim of this study was to characterize the fluctuations in the levels of natural anticoagulants, particularly TFPI, in the course of sepsis and to find out their association with the anticoagulant action of the low-molecular-weight heparin enoxaparin.

Materials And Methods: We studied 51 consecutive patients with sepsis. Blood samples were collected from patients at baseline (0 h) and at 4, 12, and 24 h after enoxaparin administration. The following assays were undertaken using commercial kits: activated partial thromboplastin time, prothrombin time, thrombin time, total and free TFPI, protein C and protein S, antithrombin, fibrinogen, and anti-factor Xa.

Results: Before enoxaparin administration, there was significant prolongation of the prothrombin time and activated partial thromboplastin time, and this remained the case in the 3 subsequent samples. There was marked reduction in the levels of antithrombin, protein C, and total and free protein S to below control values throughout the study. In contrast, plasma levels of both total and free TFPI were markedly elevated and increased after enoxaparin therapy. Anti-factor Xa levels were within the therapeutic range throughout. There was no difference in TFPI levels between those patients who died and those who survived.

Conclusion: Sepsis triggered marked release of TFPI from endothelial cells. This persisted and was increased further following the administration of enoxaparin. In contrast, there was marked consumption of the natural coagulation inhibitors antithrombin, protein C, and protein S. These results go some way towards explaining why the therapeutic use of recombinant TFPI fails to correct sepsis-associated coagulopathy.
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http://dx.doi.org/10.4274/tjh.2014.0312DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5100721PMC
June 2016

A 23 years audit of packed red blood cell consumption in a university hospital in a developing country.

Transfus Apher Sci 2015 Dec 9;53(3):300-7. Epub 2015 Jun 9.

Department of Statistics, College of Sciences and Health Professions, King Saud bin Abdulaziz University for Health Sciences, Riyadh, Saudi Arabia.

Background: There is paucity of information on the blood transfusion practice in developing countries. The current audit aims to find out the long term trend in the consumption of packed red blood cells (PRBCs) in a large Saudi teaching hospital in Riyadh

Materials And Methods: We analyzed the annual consumption of PRBCs from 1985 to 2007 in seven major hospital divisions (Medicine, General Surgery, Pediatrics, Obstetrics and Gynecology, Cardiac Surgery, Accident and Emergency and Renal Dialysis Unit) at the 850-bed King Khalid University Hospital (KKUH), Riyadh.

Results: Grand total consumption of PRBCs was 345,642 units. The consumption increased gradually and peaked in the year 1994, dropped to 30.4% 6 years later and then increased gradually thereafter, due to the expansion in the number of patients cared for in the Departments of Medicine, Cardiac Surgery and Accident and Emergency, while in the Department of Pediatrics the drop in consumption continued unabated. In the Renal Dialysis Unit consumption was minimal with the use of erythropoietin therapy. The crossmatch:transfusion ratio uncovered gross over-ordering of PRBCs and wastage of blood bank resources in most hospital divisions most notably in the Department of Obstetrics and Gynecology.

Conclusion: The results obtained indicate clearly that there has been overuse of blood products that dropped markedly in years coinciding with the worldwide apprehension about the safety of transfusion therapy particularly HIV transmission. This factor in addition to the current implementation of strict guidelines is gradually improving transfusion practices in our institute.
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http://dx.doi.org/10.1016/j.transci.2015.05.021DOI Listing
December 2015

Cardioprotective Signature of Short-Term Caloric Restriction.

PLoS One 2015 22;10(6):e0130658. Epub 2015 Jun 22.

Division of Experimental Therapeutics, Toronto General Research Institute, Toronto, Ontario, Canada; Department of Laboratory Medicine & Pathobiology, University of Toronto, Toronto, Ontario, Canada; Heart and Stroke Richard Lewar Centre of Excellence in Cardiovascular Research, University of Toronto, Toronto, Ontario, Canada; Peter Munk Cardiac Centre, University Health Network, Toronto, Ontario, Canada; Department of Medicine, University of Toronto, Toronto, Ontario, Canada; Ted Rogers Centre for Heart Research, University Health Network, Toronto, Ontario, Canada.

Objective: To understand the molecular pathways underlying the cardiac preconditioning effect of short-term caloric restriction (CR).

Background: Lifelong CR has been suggested to reduce the incidence of cardiovascular disease through a variety of mechanisms. However, prolonged adherence to a CR life-style is difficult. Here we reveal the pathways that are modulated by short-term CR, which are associated with protection of the mouse heart from ischemia.

Methods: Male 10-12 wk old C57bl/6 mice were randomly assigned to an ad libitum (AL) diet with free access to regular chow, or CR, receiving 30% less food for 7 days (d), prior to myocardial infarction (MI) via permanent coronary ligation. At d8, the left ventricles (LV) of AL and CR mice were collected for Western blot, mRNA and microRNA (miR) analyses to identify cardioprotective gene expression signatures. In separate groups, infarct size, cardiac hemodynamics and protein abundance of caspase 3 was measured at d2 post-MI.

Results: This short-term model of CR was associated with cardio-protection, as evidenced by decreased infarct size (18.5±2.4% vs. 26.6±1.7%, N=10/group; P=0.01). mRNA and miR profiles pre-MI (N=5/group) identified genes modulated by short-term CR to be associated with circadian clock, oxidative stress, immune function, apoptosis, metabolism, angiogenesis, cytoskeleton and extracellular matrix (ECM). Western blots pre-MI revealed CR-associated increases in phosphorylated Akt and GSK3ß, reduced levels of phosphorylated AMPK and mitochondrial related proteins PGC-1α, cytochrome C and cyclooxygenase (COX) IV, with no differences in the levels of phosphorylated eNOS or MAPK (ERK1/2; p38). CR regimen was also associated with reduced protein abundance of cleaved caspase 3 in the infarcted heart and improved cardiac function.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0130658PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4476723PMC
March 2016

Tumor Necrosis Factor-α Underlies Loss of Cortical Dendritic Spine Density in a Mouse Model of Congestive Heart Failure.

J Am Heart Assoc 2015 May 6;4(5). Epub 2015 May 6.

Tanz Center for Research in Neurodegenerative Diseases, Toronto, Ontario, Canada (R.F., B.M.F., L.N.H.).

Background: Heart failure (HF) is a progressive disorder characterized by reduced cardiac output and increased peripheral resistance, ultimately leading to tissue perfusion deficits and devastating consequences for several organs including the brain. We previously described a tumor necrosis factor-α (TNF-α)-dependent enhancement of posterior cerebral artery tone and concomitant reduced cerebral blood flow in a mouse model of early HF in which blood pressure remains minimally affected. HF is often associated with cognitive impairments such as memory deficits, even before any overt changes in brain structure and function occur. The pathophysiology underlying the development of cognitive impairments in HF is unknown, and appropriate treatment strategies are lacking.

Methods And Results: We used a well-established mouse model in which HF was induced by experimental myocardial infarction produced by permanent surgical ligation of the left anterior descending coronary artery (infarct size ≈25% of the left ventricular wall). Ligated mice developed enlarged hearts, congested lungs, and reduced cardiac output and blood pressure, with elevated peripheral resistance within 6 to 8 weeks after ligation. In this study, we demonstrated the significance of the proinflammatory cytokine TNF-α during HF-mediated neuroinflammation and associated impaired hippocampus-independent nonspatial episodic memory function. Augmented cerebral TNF-α expression and microglial activation in HF mice, indicative of brain inflammation, were accompanied by morphological changes and significant reduction of cortical dendritic spines (61.39±8.61% for basal and 61.04±9.18% for apical spines [P<0.001]). The significance of TNF-α signaling during the observed HF-mediated neurodegenerative processes is supported by evidence showing that sequestration or genetic deletion of TNF-α ameliorates the observed reduction of cortical dendritic spines (33.51±7.63% for basal and 30.13±6.98% for apical spines in wild-type mice treated with etanercept; 17.09±6.81% for basal and 17.21±7.29% for apical spines in TNF-α(-/-)). Moreover, our data suggest that alterations in cerebral serum and glucocorticoid-inducible kinase 1 (SgK1) expression and phosphorylation during HF may be TNF-α dependent and that an increase of SgK1 phosphorylation potentially plays a role in the HF-associated reduction of dendritic spine density.

Conclusions: Our findings demonstrate that TNF-α plays a pivotal role in HF-mediated neuroinflammation and associated alterations of cortical dendritic spine density and has the potential to reveal novel treatment strategies for HF-associated memory deficits.
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http://dx.doi.org/10.1161/JAHA.115.001920DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4599420PMC
May 2015

Factors affecting the attractiveness of medical tourism destination: an empirical study on India- review article.

Iran J Public Health 2014 Jul;43(7):867-76

1. Dept. of Business Administration, Faculty of Economics & Management Sciences, International Islamic University Malaysia, Kuala Lumpur, Malaysia.

Background: In this edge, medical tourism is not a new idea. Medical treatment is one of the essential demands of human beings and it requires high quality and intensive care. Beside western world, few developing countries are playing key roles as medical tourism destinations. India is one of the leading names among these countries. The purpose of the paper is to find the factors influencing the attractiveness of India as a health tourism destination.

Methods: The study has found the major contributing factors and their relative importance in the attractiveness of the health tourism destination that is India from consumers' perspectives by conducting survey with an application of structural equation modelling approach.

Results: In Indian context, medical tourists consider service quality and cost mostly to select any medical destination. In addition they also give value to the destination competitiveness but tourist attitude is less important in comparison with other factors affecting their destination choice. Since the study has used structural equation modelling approach to test the hypothesis and figure out the relative importance of the factors, the fundamental indices such as Normed Chi square(less than 3), RMSEA (less than 0.08) and CFI (more than 0.90) values show the overall model fit of the proposed model.

Conclusion: In order to transform a country such as India as an attractive and competitive medical tourist destination in this time of globalization, a step should be taken to control cost ensuring the quality of services.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4401052PMC
July 2014

Thioredoxin-Interacting Protein Deficiency Protects against Diabetic Nephropathy.

J Am Soc Nephrol 2015 Dec 8;26(12):2963-77. Epub 2015 Apr 8.

Department of Medicine and Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto General Research Institute, University Health Network, Department of Physiology, Banting and Best Diabetes Centre, and

Expression of thioredoxin-interacting protein (TxNIP), an endogenous inhibitor of the thiol oxidoreductase thioredoxin, is augmented by high glucose (HG) and promotes oxidative stress. We previously reported that TxNIP-deficient mesangial cells showed protection from HG-induced reactive oxygen species, mitogen-activated protein kinase phosphorylation, and collagen expression. Here, we investigated the potential role of TxNIP in the pathogenesis of diabetic nephropathy (DN) in vivo. Wild-type (WT) control, TxNIP(-/-), and TxNIP(+/-) mice were rendered equally diabetic with low-dose streptozotocin. In contrast to effects in WT mice, diabetes did not increase albuminuria, proteinuria, serum cystatin C, or serum creatinine levels in TxNIP(-/-) mice. Whereas morphometric studies of kidneys revealed a thickened glomerular basement membrane and effaced podocytes in the diabetic WT mice, these changes were absent in the diabetic TxNIP(-/-) mice. Immunohistochemical analysis revealed significant increases in the levels of glomerular TGF-β1, collagen IV, and fibrosis only in WT diabetic mice. Additionally, only WT diabetic mice showed significant increases in oxidative stress (nitrotyrosine, urinary 8-hydroxy-2-deoxy-guanosine) and inflammation (IL-1β mRNA, F4/80 immunohistochemistry). Expression levels of Nox4-encoded mRNA and protein increased only in the diabetic WT animals. A significant loss of podocytes, assessed by Wilms' tumor 1 and nephrin staining and urinary nephrin concentration, was found in diabetic WT but not TxNIP(-/-) mice. Furthermore, in cultured human podocytes exposed to HG, TxNIP knockdown with siRNA abolished the increased mitochondrial O2 (-) generation and apoptosis. These data indicate that TxNIP has a critical role in the progression of DN and may be a promising therapeutic target.
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http://dx.doi.org/10.1681/ASN.2014050528DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4657825PMC
December 2015

Hydrogels with integrin-binding angiopoietin-1-derived peptide, QHREDGS, for treatment of acute myocardial infarction.

Circ Heart Fail 2015 Mar 28;8(2):333-41. Epub 2015 Jan 28.

From the Institute of Biomaterials and Biomedical Engineering (L.A.R., N.F., C.L., M.R.) and Department of Chemical Engineering and Applied Chemistry (L.L.Y.C., M.R.), University of Toronto, Canada; and Toronto General Research Institute, University Health Network, Canada (J.W., A.M., R.-K.L.).

Background: Hydrogels are being actively investigated for direct delivery of cells or bioactive molecules to the heart after myocardial infarction (MI) to prevent cardiac functional loss. We postulate that immobilization of the prosurvival angiopoietin-1-derived peptide, QHREDGS, to a chitosan-collagen hydrogel could produce a clinically translatable thermoresponsive hydrogel to attenuate post-MI cardiac remodeling.

Methods And Results: In a rat MI model, QHREDGS-conjugated hydrogel (QHG213H), control gel, or PBS was injected into the peri-infarct/MI zone. By in vivo tracking and chitosan staining, the hydrogel was demonstrated to remain in situ for 2 weeks and was cleared in ≈3 weeks. By echocardiography and pressure-volume analysis, the QHG213H hydrogel significantly improved cardiac function compared with the controls. Scar thickness and scar area fraction were also significantly improved with QHG213H gel injection compared with the controls. There were significantly more cardiomyocytes, determined by cardiac troponin-T staining, in the MI zone of the QHG213H hydrogel group; and hydrogel injection did not induce a significant inflammatory response as assessed by polymerase chain reaction and an inflammatory cytokine assay. The interaction of cardiomyocytes and cardiac fibroblasts with QHREDGS was found to be mediated by β1-integrins.

Conclusions: We demonstrated for the first time that the QHG213H peptide-modified hydrogel can be injected in the beating heart where it remains localized for a clinically effective period. Moreover, the QHG213H hydrogel induced significant cardiac functional and morphological improvements after MI relative to the controls.
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http://dx.doi.org/10.1161/CIRCHEARTFAILURE.114.001881DOI Listing
March 2015

Enhanced proliferation and altered calcium handling in RGS2-deficient vascular smooth muscle cells.

J Recept Signal Transduct Res 2014 Dec 20;34(6):476-83. Epub 2014 May 20.

Division of Experimental Therapeutics, Toronto General Research Institute , University Health Network, Toronto, Ontario , Canada and.

Context: Regulator of G-protein signaling-2 (RGS2) inhibits Gq-mediated regulation of Ca(2+) signalling in vascular smooth muscle cells (VSMC).

Objective: RGS2 knockout (RGS2KO) mice are hypertensive and show arteriolar remodeling. VSMC proliferation modulates intracellular Ca(2+) concentration [Ca(2+)]i. RGS2 involvement in VSMC proliferation had not been examined.

Methods: Thymidine incorporation and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) conversion assays measured cell proliferation. Fura-2 ratiometric imaging quantified [Ca(2+)]i before and after UTP and thapsigargin. [(3)H]-labeled inositol was used for phosphoinositide hydrolysis. Quantitative RT-PCR and confocal immunofluorescence of select Ca(2+) transporters was performed in primary aortic VSMC.

Results And Discussion: Platelet-derived growth factor (PDGF) increased S-phase entry and proliferation in VSMC from RGS2KO mice to a greater extent than in VSMC from wild-type (WT) controls. Consistent with differential PDGF-induced changes in Ca(2+) homeostasis, RGS2KO VSMC showed lower resting [Ca(2+)]i but higher thapsigargin-induced [Ca(2+)]i as compared with WT. RGS2KO VSMC expressed lower mRNA levels of plasma membrane Ca(2+) ATPase-4 (PMCA4) and Na(+) Ca(2+) Exchanger (NCX), but higher levels of sarco-endoplasmic reticulum Ca(2+) ATPase-2 (SERCA2). Western blot and immunofluorescence revealed similar differences in PMCA4 and SERCA2 protein, while levels of NCX protein were not reduced in RGS2KO VSMC. Consistent with decreased Ca(2+) efflux activity, (45)Ca-extrusion rates were lower in RGS2KO VSMC. These differences were reversed by the PMCA inhibitor La(3+), but not by replacing extracellular Na(+) with choline, implicating differences in the activity of PMCA and not NCX.

Conclusion: RGS2-deficient VSMC exhibit higher rates of proliferation and coordinate plasticity of Ca(2+)-handling mechanisms in response to PDGF stimulation.
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http://dx.doi.org/10.3109/10799893.2014.920393DOI Listing
December 2014

p27 protein protects metabolically stressed cardiomyocytes from apoptosis by promoting autophagy.

J Biol Chem 2014 Jun 2;289(24):16924-35. Epub 2014 May 2.

From the Toronto General Research Institute, Peter Munk Cardiac Centre, and McEwen Centre for Regenerative Medicine, University Health Network, Toronto, Ontario M5G 2C4, Canada, and the Department of Medicine and Heart and Stroke/Richard Lewar Centre of Excellence, University of Toronto, Toronto M5G 1L7, Canada

p27(Kip1) (p27), a key regulator of cell division, has been implicated in autophagy of cancer cells. However, its role in autophagy, the evolutionarily conserved catabolic process that enables cells to remove unwanted proteins and damaged organelles, had not been examined in the heart. Here we report that ectopic delivery of a p27 fusion protein (TAT-p27) was sufficient to induce autophagy in neonatal rat ventricular cardiomyocytes in vitro, under basal conditions and after glucose deprivation. Conversely, lentivirus-delivered shRNA against p27 successfully reduced p27 levels and suppressed basal and glucose-deprived levels of autophagy in cardiomyocytes in vitro. Glucose deprivation mimics myocardial ischemia and induces apoptosis in cardiomyocytes. During glucose deprivation, TAT-p27 inhibited apoptosis, whereas down-regulation of p27 decreased survival of cardiomyocytes. However, inhibition of autophagy by pharmacological (3-methyladenine, chloroquine, or bafilomycin A1) or genetic approaches (siRNA-mediated knockdown of Atg5) sensitized cardiomyocytes to glucose deprivation-induced apoptosis, even in the presence of TAT-p27. TAT-p27 was also able to provoke greater levels of autophagy in resting and fasting cardiomyocytes in vivo. Further, TAT-p27 enhanced autophagy and repressed cardiomyocytes apoptosis, improved cardiac function, and reduced infarct size following myocardial infarction. Again, these effects were lost when cardiac autophagy in vivo was blocked by chloroquine. Taken together, these data show that p27 positively regulates cardiac autophagy in vitro and in vivo, at rest and after metabolic stress, and that TAT-p27 inhibits apoptosis by promoting autophagy in glucose-deprived cardiomyocytes in vitro and in post-myocardial infarction hearts in vivo.
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http://dx.doi.org/10.1074/jbc.M113.542795DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4059136PMC
June 2014

Calcium efflux activity of plasma membrane Ca2+ ATPase-4 (PMCA4) mediates cell cycle progression in vascular smooth muscle cells.

J Biol Chem 2014 Mar 21;289(10):7221-31. Epub 2014 Jan 21.

From the Division of Experimental Therapeutics, Toronto General Research Institute, University Health Network, Toronto, Ontario M5G 2C4, Canada.

We explored the role played by plasma membrane calcium ATPase-4 (PMCA4) and its alternative splice variants in the cell cycle of vascular smooth muscle cells (VSMC). A novel variant (PMCA4e) was discovered. Quantitative real-time-PCR-quantified PMCA4 splice variant proportions differed in specific organs. The PMCA4a:4b ratio in uninjured carotid arteries (∼1:1) was significantly reduced by wire denudation injury (to ∼1:3) by modulation of alternative splicing, as confirmed by novel antibodies against PMCA4a/e and PMCA4b. Laser capture microdissection localized this shift to the media and adventitia. Primary carotid VSMC from PMCA4 knock-out (P4KO) mice showed impaired [(3)H]thymidine incorporation and G1 phase arrest as compared with wild type (P4WT). Electroporation of expression constructs encoding PMCA4a, PMCA4b, and a PMCA4b mutant lacking PDZ binding rescued this phenotype of P4KO cells, whereas a mutant with only 10% of normal Ca(2+) efflux activity could not. Microarray of early G1-synchronized VSMC showed 39-fold higher Rgs16 (NFAT (nuclear factor of activated T-cells) target; MAPK inhibitor) and 69-fold higher Decorin (G1 arrest marker) expression in P4KO versus P4WT. Validation by Western blot also revealed decreased levels of Cyclin D1 and NFATc3 in P4KO. Microarrays of P4KO VSMC rescued by PMCA4a or PMCA4b expression showed reversal of perturbed Rgs16, Decorin, and NFATc3 expression levels. However, PMCA4a rescue caused a 44-fold reduction in AP-2β, a known anti-proliferative transcription factor, whereas PMCA4b rescue resulted in a 50-fold reduction in p15 (Cyclin D1/Cdk4 inhibitor). We conclude that Ca(2+) efflux activity of PMCA4 underlies G1 progression in VSMC and that PMCA4a and PMCA4b differentially regulate specific downstream mediators.
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http://dx.doi.org/10.1074/jbc.M113.533638DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3945381PMC
March 2014

Mutation in integrin-linked kinase (ILK(R211A)) and heat-shock protein 70 comprise a broadly cardioprotective complex.

PLoS One 2013 18;8(11):e77331. Epub 2013 Nov 18.

Division of Cardiovascular Research, Hospital for Sick Children, Toronto, Canada.

Rationale: Integrin-linked kinase (ILK) has been proposed as a novel molecular target that has translational potential in diverse cardiac diseases, since its upregulation promotes a broadly cardioprotective phenotype. However, ILK has been implicated as both a cardioprotective and oncogenic target, which imposes therapeutic constraints that are generally relevant to the translational potential of many kinases.

Objective: To study the cardioprotective properties of the activation-resistant, non-oncogenic, mutation of ILK (ILK(R211A)) against experimental MI in vivo and Doxorubicin induced apoptosis in vitro and it's relationships to stress induced heat shock proteins.

Methods/results: The transgenic mouse heart over-expressing a point mutation in the ILK pleckstrin homology (PH) domain (Tg(R211A)) exhibits a highly cardioprotective phenotype based on LAD-ligation-induced MI reduction in vivo, and on protection against doxorubicin (DOX)-induced cardiomyocyte apoptosis when overexpressed in human induced pluripotent stem cell (iPS)-derived cardiomyocytes in vitro. Intriguingly, the degree of cardioprotection seen with the ILK(R211A) mutation exceeded that with the ILK(S343D) mutation. Microarray and immunoprecipitation analyses revealed upregulation of expression levels and specific binding of ILK(WT), ILK(S343D) and ILK(R211A) to both constitutively active heat-shock protein 70 (Hsc70) and inducible Hsp70 in response to MI, and to acute ILK overexpression in iPSC-cardiomyocytes. ILK-mediated cardioprotection was shown to depend upon Hsp70 ATPase activity.

Conclusions: These findings indicate that wild type ILK and the non-oncogenic ILK(R211A) mutation comprise a cardioprotective module with Hsp/c70. These results advance a novel target discovery theme in which kinase mutations can be safely engineered to enhance cardioprotective effects.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0077331PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3832499PMC
July 2014

Clotting factor VIII (FVIII) and thrombin generation in camel plasma: A comparative study with humans.

Can J Vet Res 2013 Apr;77(2):150-7

The Coagulation Research Laboratory, Physiology Department, College of Medicine and King Khalid University Hospital (Gader, Al Momen, Alhaider) and College of Agriculture and Food Sciences (Al Haidary, Hussain), King Saud University, Riyadh 11461, Saudi Arabia; Comparative Coagulation Section, Animal Health Diagnostic Center, Cornell University, Ithaca, New York, USA (Brooks, Catalfamo).

The objective of this study was to characterize the highly elevated levels of clotting factor VIII (FVIII) in camel plasma. Whole blood was collected from healthy camels and factor VIII clotting activity (FVIII:C) assays were conducted using both the clotting and the chromogenic techniques. The anticoagulant citrate phosphate dextrose adenine (CPDA) produced the highest harvest of FVIII:C, the level of plasma factor VIII, compared to heparin:saline and heparin:CPDA anticoagulants. Camel FVIII can be concentrated 2 to 3 times in cryoprecipitate. There was a significant loss of camel FVIII when comparing levels of FVIII in camel plasma after 1 h of incubation at 37°C (533%), 40°C (364%), and 50°C (223%). Thrombin generation of camel plasma is comparable to that of human plasma. It was concluded that camel plasma contains very elevated levels of FVIII:C, approaching 8 times the levels in human plasma, and that these elevated levels could not be attributed to excessive thrombin generation. Unlike human FVIII:C, camel FVIII:C is remarkably heat stable. Taken together, these unique features of camel FVIII could be part of the physiological adaptation of hemostasis of the Arabian camel in order to survive in the hot desert environment.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3605932PMC
April 2013

Inhibition of Src kinase blocks high glucose-induced EGFR transactivation and collagen synthesis in mesangial cells and prevents diabetic nephropathy in mice.

Diabetes 2013 Nov 13;62(11):3874-86. Epub 2013 Aug 13.

Toronto General Research Institute, University Health Network, University of Toronto, Toronto, Ontario, Canada.

Chronic exposure to high glucose leads to diabetic nephropathy characterized by increased mesangial matrix protein (e.g., collagen) accumulation. Altered cell signaling and gene expression accompanied by oxidative stress have been documented. The contribution of the tyrosine kinase, c-Src (Src), which is sensitive to oxidative stress, was examined. Cultured rat mesangial cells were exposed to high glucose (25 mmol/L) in the presence and absence of Src inhibitors (PP2, SU6656), Src small interfering RNA (siRNA), and the tumor necrosis factor-α-converting enzyme (TACE) inhibitor, TAPI-2. Src was investigated in vivo by administration of PP2 to streptozotocin (STZ)-induced diabetic DBA2/J mice. High glucose stimulated Src, TACE, epidermal growth factor receptor (EGFR), mitogen-activated protein kinases (MAPKs), extracellular signal-regulated kinase (ERK1/2, p38), and collagen IV accumulation in mesangial cells. PP2 and SU6656 blocked high glucose-stimulated phosphorylation of Src Tyr-416, EGFR, and MAPKs. These inhibitors and Src knockdown by siRNA, as well as TAPI-2, also abrogated high glucose-induced phosphorylation of these targets and collagen IV accumulation. In STZ-diabetic mice, albuminuria, increased Src pTyr-416, TACE activation, ERK and EGFR phosphorylation, glomerular collagen accumulation, and podocyte loss were inhibited by PP2. These data indicate a role for Src in a high glucose-Src-TACE-heparin-binding epidermal growth factor-EGFR-MAPK-signaling pathway to collagen accumulation. Thus, Src may provide a novel therapeutic target for diabetic nephropathy.
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http://dx.doi.org/10.2337/db12-1010DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3806624PMC
November 2013

Controlled release of thymosin β4 from injected collagen-chitosan hydrogels promotes angiogenesis and prevents tissue loss after myocardial infarction.

Regen Med 2012 Jul;7(4):523-33

Chemical Engineering & Applied Chemistry, University of Toronto, ON, Canada.

Aims: Acute myocardial infarction (MI) leads to fibrosis and severe left ventricular wall thinning. Enhancing vascularization within the infarct reduces cell death and maintains a thick left ventricular wall, which is essential for proper cardiac function. Here, we evaluated the controlled delivery of thymosin β4 (Tβ4), which supports cardiomyocyte survival by inducing vascularization and upregulating Akt activity, in the treatment of MI.

Materials & Methods: We injected collagen-chitosan hydrogel with controlled release of Tβ4 into the infarct after performing left anterior descending artery ligation in rats.

Results: Tβ4-encapsulated hydrogel (thymosin) significantly reduced tissue loss post-MI (13 ± 4%), compared with 58 ± 3% and 30 ± 8% tissue loss for no treatment (MI only) and Tβ4-free hydrogel (control). Significantly more Factor VIII-positive blood vessels with diameter >50 µm were in the thymosin group compared with both MI only and control (p < 0.0001), showing Tβ4-induced vascularization. Wall thickness was positively correlated with the mature blood vessel density (r = 0.9319; p < 0.0001).

Conclusion: Controlled release of Tβ4 within the infarct enhances angiogenesis and presence of cardiomyocytes that are necessary for cardiac repair.
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http://dx.doi.org/10.2217/rme.12.35DOI Listing
July 2012