Publications by authors named "Stephen McCarthy"

40 Publications

The National Endoscopy Database (NED) Automated Performance Reports to Improve Quality Outcomes Trial (APRIQOT) randomized controlled trial design.

Endosc Int Open 2020 Nov 21;8(11):E1545-E1552. Epub 2020 Oct 21.

North Tees and Hartlepool NHL Foundation Trust - Gastroenterology, Stockton on Tees, United Kingdom of Great Britain and Northern Ireland.

Colonoscopists with low polyp detection have higher post colonoscopy colorectal cancer incidence and mortality rates. The United Kingdom's National Endoscopy Database (NED) automatically captures patient level data in real time and provides endoscopy key performance indicators (KPI) at a national, endoscopy center, and individual level. Using an electronic behavior change intervention, the primary objective of this study is to assess if automated feedback of endoscopist and endoscopy center-level optimal procedure-adjusted detection KPI (opadKPI) improves polyp detection performance. This multicenter, prospective, cluster-randomized controlled trial is randomizing NHS endoscopy centres to either intervention or control. The intervention is targeted at independent colonoscopists and each center's endoscopy lead. The intervention reports are evidence-based from endoscopist qualitative interviews and informed by psychological theories of behavior. NED automatically creates monthly reports providing an opadKPI, using mean number of polyps, and an action plan. The primary outcome is opadKPI comparing endoscopists in intervention and control centers at 9 months. Secondary outcomes include other KPI and proximal detection measures at 9 and 12 months. A nested histological validation study will correlate opadKPI to adenoma detection rate at the center level. A cost-effectiveness and budget impact analysis will be undertaken. If the intervention is efficacious and cost-effective, we will showcase the potential of this learning health system, which can be implemented at local and national levels to improve colonoscopy quality, and demonstrate that an automated system that collects, analyses, and disseminates real-time clinical data can deliver evidence- and theory-informed feedback.
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http://dx.doi.org/10.1055/a-1261-3151DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7584467PMC
November 2020

World Café approach: exploring the future vision of oral anticoagulants for patients with atrial fibrillation (AF) in Ireland.

BMJ Open 2020 09 24;10(9):e036493. Epub 2020 Sep 24.

Department of Economics, Cork University Business School, University College Cork, Cork, Ireland.

Objectives: To explore and reflect on the current anticoagulation therapy offered to patients with atrial fibrillation (AF), potential challenges and the future vision for oral anticoagulants for patients with AF and healthcare professionals in Ireland.

Design: A multistakeholder focus group using a World Café approach.

Participants: Nine participants from academic, clinical and health backgrounds attended the focus group together with a facilitator.

Results: Enhanced patient empowerment; more effective use of technology and developing system-based medical care pathways would provide improved supports for AF management. The challenges in providing these include cost and access issues, the doctor-patient relationship and the provision of education. While consensus for developing evidence-based pathways to maximise efficiency and effectiveness of AF treatment was evident, it would require a shared vision between stakeholders of integrated care. The benefits of embracing technological advances for clinicians and patients were evident; however, clinicians indicate this can increase pressure on already stretched resources; coupled with institutional barriers (including scarce resources) arising from the complex nature of anticoagulation for patients with AF, which emerged strongly. Including the unpredictable nature of warfarin, hidden costs associated with monitoring, adverse clinical effects, different patient cohorts (including those prescribed anticoagulant for the first time vs those switching from warfarin to a new oral anticoagulant (NOAC)), non-adherence concerns and undesirable impacts on patients' daily lives.

Conclusions: While anticoagulation therapy for patients with AF using NOACs has been widely adopted and is diffusing into routine practice, significant operationalisation issues and barriers to effective treatment/management persist. The reflections reported in this study are a catalyst for future discussion and research.
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http://dx.doi.org/10.1136/bmjopen-2019-036493DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7517561PMC
September 2020

Embedding the Pillars of Quality in Health Information Technology Solutions Using "Integrated Patient Journey Mapping" (IPJM): Case Study.

JMIR Hum Factors 2020 Sep 17;7(3):e17416. Epub 2020 Sep 17.

Department of Business Information Systems, Cork University Business School, University College Cork, Cork, Ireland.

Background: Health information technology (HIT) and associated data analytics offer significant opportunities for tackling some of the more complex challenges currently facing the health care sector. However, to deliver robust health care service improvements, it is essential that HIT solutions be designed by parallelly considering the 3 core pillars of health care quality: clinical effectiveness, patient safety, and patient experience. This requires multidisciplinary teams to design interventions that both adhere to medical protocols and achieve the tripartite goals of effectiveness, safety, and experience.

Objective: In this paper, we present a design tool called Integrated Patient Journey Mapping (IPJM) that was developed to assist multidisciplinary teams in designing effective HIT solutions to address the 3 core pillars of health care quality. IPJM is intended to support the analysis of requirements as well as to promote empathy and the emergence of shared commitment and understanding among multidisciplinary teams.

Methods: A 6-month, in-depth case study was conducted to derive findings on the use of IPJM during Learning to Evaluate Blood Pressure at Home (LEANBH), a connected health project that developed an HIT solution for the perinatal health context. Data were collected from over 700 hours of participant observations and 10 semistructured interviews.

Results: The findings indicate that IPJM offered a constructive tool for multidisciplinary teams to work together in designing an HIT solution, through mapping the physical and emotional journey of patients for both the current service and the proposed connected health service. This allowed team members to consider the goals, tasks, constraints, and actors involved in the delivery of this journey and to capture requirements for the digital touchpoints of the connected health service.

Conclusions: Overall, IPJM facilitates the design and implementation of complex HITs that require multidisciplinary participation.
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http://dx.doi.org/10.2196/17416DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7530692PMC
September 2020

Inhibition of Ebola infection by anti-parasitic quinoline derivatives.

F1000Res 2020 17;9:268. Epub 2020 Apr 17.

Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, M5H 2N2, Canada.

There continues to be no approved drugs for the treatment of Ebola virus disease (EVD). Despite a number of candidate drugs showing limited efficacy and/or in non-human primate studies, EVD continues to plaque certain areas of Africa without any efficacious treatments yet available. Recently, we have been exploring the potential for anti-malarial drugs to inhibit an model of Ebola Zaire replication using a transcription-competent virus-like particle (trVLP) assay. We examined the efficacy of chloroquine, amodiaquine and 36 novel anti-parasite quinoline derivatives at inhibiting Ebola virus replication. Drug efficacy was tested by trVLP assay and toxicity by MTT assay. Both chloroquine and amodiaquine were effective for inhibition of Ebola virus replication without significant toxicity. The half-maximal inhibitory concentration (IC ) of chloroquine and amodiaquine to inhibit Ebola virus replication were IC = 3.95 µM and IC = 1.45 µM, respectively. Additionally, three novel quinoline derivatives were identified as having inhibitory activity and low toxicity for Ebola trVLP replication, with 2NH2Q being the most promising derivative, with an IC of 4.66 µM. Quinoline compounds offer many advantages for disease treatment in tropical climates as they are cheap to produce, easy to synthesize and chemically stable. In this report, we have demonstrated the potential of anti-parasite quinolines for further investigation for use in EVD.
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http://dx.doi.org/10.12688/f1000research.22352.1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7268155PMC
March 2021

A Chemical Biology Approach to Probing the Folding Pathways of the Inhibitory Cystine Knot (ICK) Peptide ProTx-II.

Front Chem 2020 3;8:228. Epub 2020 Apr 3.

Department of Chemistry, UCL, London, United Kingdom.

Peptide toxins that adopt the inhibitory cystine knot (ICK) scaffold have very stable three-dimensional structures as a result of the conformational constraints imposed by the configuration of the three disulfide bonds that are the hallmark of this fold. Understanding the oxidative folding pathways of these complex peptides, many of which are important therapeutic leads, is important in order to devise reliable synthetic routes to correctly folded, biologically active peptides. Previous research on the ICK peptide ProTx-II has shown that in the absence of an equilibrating redox buffer, misfolded intermediates form that prevent the formation of the native disulfide bond configuration. In this paper, we used tandem mass spectrometry to examine these misfolded peptides, and identified two non-native singly bridged peptides, one with a Cys(III)-Cys(IV) linkage and one with a Cys(V)-Cys(VI) linkage. Based on these results, we propose that the -terminus of ProTx-II has an important role in initiating the folding of this peptide. To test this hypothesis, we have also studied the folding pathways of analogs of ProTx-II containing the disulfide-bond directing group penicillamine (Pen) under the same conditions. We find that placing Pen residues at the -terminus of the ProTx-II analogs directs the folding pathway away from the singly bridged misfolded intermediates that represent a kinetic trap for the native sequence, and allows a fully oxidized final product to be formed with three disulfide bridges. However, multiple two-disulfide peptides were also produced, indicating that further study is required to fully control the folding pathways of this modified scaffold.
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http://dx.doi.org/10.3389/fchem.2020.00228DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7145985PMC
April 2020

Impact of emergency care centralisation on mortality and efficiency: a retrospective service evaluation.

Emerg Med J 2020 Apr 7;37(4):180-186. Epub 2020 Jan 7.

Faculty of Health and Life Sciences, Northumbria University, Newcastle upon Tyne, UK.

Objective: Evidence favours centralisation of emergency care for specific conditions, but it remains unclear whether broader implementation improves outcomes and efficiency. Routine healthcare data examined consolidation of three district general hospitals with mixed medical admission units (MAU) into a single high-volume site directing patients from the ED to specialty wards with consultant presence from 08:00 to 20:00.

Methods: Consecutive unscheduled adult index admissions from matching postcode areas were identified retrospectively in Hospital Episode Statistics over a 3-year period: precentralisation baseline (from 16 June 2014 to 15 June 2015; n=18 586), year 1 postcentralisation (from 16 June 2015 to 15 June 2016; n=16 126) and year 2 postcentralisation (from 16 June 2016 to 15 June 2017; n=17 727). Logistic regression including key demographic covariates compared baseline with year 1 and year 2 probabilities of mortality and daily discharge until day 60 after admission and readmission within 60 days of discharge.

Results: Relative to baseline, admission postcentralisation was associated with favourable OR (95% CI) for day 60 mortality (year 1: 0.95 (0.88 to 1.02), p=0.18; year 2: 0.94 (0.91 to 0.97), p<0.01), mainly among patients aged 80+ years (year 1: 0.88 (0.79 to 0.97); year 2: 0.91 (0.87 to 0.96)). The probability of being discharged alive on any day since admission increased (year 1: 1.07 (1.04 to 1.10), p<0.01; year 2: 1.04 (1.02 to 1.05), p<0.01) and the risk of readmission decreased (year 1: 0.90 (0.87 to 0.94), p<0.01; year 2: 0.92 (0.90 to 0.94), p<0.01).

Conclusion: A centralised site providing early specialist care was associated with improved short-term outcomes and efficiency relative to lower volume ED admitting to MAU, particularly for older patients.
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http://dx.doi.org/10.1136/emermed-2019-208539DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7146926PMC
April 2020

Targeting ABL1 or ARG Tyrosine Kinases to Restrict HIV-1 Infection in Primary CD4+ T-Cells or in Humanized NSG Mice.

J Acquir Immune Defic Syndr 2019 12;82(4):407-415

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

Background: Previous studies support dasatinib as a potent inhibitor of HIV-1 replication. However, a functional distinction between 2 kinase targets of the drug, ABL1 and ARG, has not been assessed.

Setting: We used primary CD4 T-cells, CD8-depleted peripheral blood mononuclear cells (PBMCs) from a treatment naïve HIV-1 patient, and a humanized mouse model of HIV-1 infection. We assessed the roles of ABL1 and ARG during HIV-1 infection and use of dasatinib as a potential antiviral against HIV-1 in humanized mice.

Methods: Primary CD4 T-cells were administered siRNA targeting ABL1 or ARG, then infected with HIV-1 containing luciferase reporter viruses. Quantitative polymerase chain reaction of viral integration of 4 HIV-1 strains was also assessed. CD8-depleted PBMCs were treated for 3 weeks with dasatinib. NSG mice were engrafted with CD34 pluripotent stem cells from human fetal cord blood, and infected with Ba-L virus after 19 weeks. Mice were treated daily with dasatinib starting 5 weeks after infection.

Results: siRNA knockdown of ABL1 or ARG had no effect on viral reverse transcripts, but increased 2-LTR circles 2- to 4-fold and reduced viral integration 2- to 12-fold. siRNA knockdown of ARG increased SAMHD1 activation, whereas knockdown of either kinase reduced RNA polymerase II activation. Treating CD8-depleted PBMCs from a treatment-naïve patient with 50 nM of dasatinib for 3 weeks reduced p24 levels by 99.8%. Ba-L (R5)-infected mice injected daily with dasatinib showed a 95.1% reduction in plasma viral load after 2 weeks of treatment.

Conclusions: We demonstrate a novel nuclear role for ABL1 and ARG in ex vivo infection experiments, and proof-of-principle use of dasatinib in a humanized mouse model of HIV-1 infection.
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http://dx.doi.org/10.1097/QAI.0000000000002144DOI Listing
December 2019

Determining isoleucine side-chain rotamer-sampling in proteins from C chemical shift.

Chem Commun (Camb) 2019 Dec 23;55(94):14107-14110. Epub 2019 Oct 23.

Institute of Structural and Molecular Biology, Division of Biosciences, University College London, London, UKWC1E 6BT.

Chemical shifts are often the only nuclear magnetic resonance parameter that can be obtained for challenging macromolecular systems. Here we present a framework to derive the conformational sampling of isoleucine side chains from C chemical shifts and demonstrate that side-chain conformations in a low-populated folding intermediate can be determined.
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http://dx.doi.org/10.1039/c9cc06496fDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7138115PMC
December 2019

The Patient-Held Active Record of Medication Status (PHARMS) study: a mixed-methods feasibility analysis.

Br J Gen Pract 2019 May;69(682):e345-e355

School of Public Health, University College Cork, Cork.

Background: Medication errors frequently occur as patients transition between hospital and the community, and may result in patient harm. Novel methods are required to address this issue.

Aim: To assess the feasibility of introducing an electronic patient-held active record of medication status device (PHARMS) at the primary-secondary care interface at the time of hospital discharge.

Design And Setting: A mixed-methods study (non-randomised controlled intervention, and a process evaluation of qualitative interviews and non-participant observation) among patients >60 years in an urban hospital and general practices in Cork, Ireland.

Method: The number and clinical significance of errors were compared between discharge prescriptions of the intervention (issued with a PHARMS device) and control (usual care, handwritten discharge prescription) groups. Semi-structured interviews were conducted with patients, junior doctors, GPs, and IT professionals, in addition to direct observation of the implementation process.

Results: In all, 102 patients were included in the final analysis (intervention = 41, control = 61). Total error number was lower in the intervention group (median 1, interquartile range [IQR] 0-3) than in the control group (median 8, IQR (4-13.5, <0.001), with the clinical significance score in the intervention group also being lower than the control group (median 2, IQR 0-4 versus median 11, IQR 5-20, <0.001). The PHARMS device was found to be technically implementable using existing information technology infrastructure, and acceptable to all key stakeholders.

Conclusion: The results suggest that using PHARMS devices within existing systems in general practice and hospitals is feasible and acceptable to both patients and doctors, and may reduce medication error.
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http://dx.doi.org/10.3399/bjgp19X702413DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6478471PMC
May 2019

The Role of Disulfide Bond Replacements in Analogues of the Tarantula Toxin ProTx-II and Their Effects on Inhibition of the Voltage-Gated Sodium Ion Channel Na1.7.

J Am Chem Soc 2017 09 7;139(37):13063-13075. Epub 2017 Sep 7.

Department of Chemistry, University College London , 20 Gordon Street, London WC1H 0AJ, United Kingdom.

Spider venom toxins, such as Protoxin-II (ProTx-II), have recently received much attention as selective Na1.7 channel blockers, with potential to be developed as leads for the treatment of chronic nocioceptive pain. ProTx-II is a 30-amino acid peptide with three disulfide bonds that has been reported to adopt a well-defined inhibitory cystine knot (ICK) scaffold structure. Potential drawbacks with such peptides include poor pharmacodynamics and potential scrambling of the disulfide bonds in vivo. In order to address these issues, in the present study we report the solid-phase synthesis of lanthionine-bridged analogues of ProTx-II, in which one of the three disulfide bridges is replaced with a thioether linkage, and evaluate the biological properties of these analogues. We have also investigated the folding and disulfide bridging patterns arising from different methods of oxidation of the linear peptide precursor. Finally, we report the X-ray crystal structure of ProTx-II to atomic resolution; to our knowledge this is the first crystal structure of an ICK spider venom peptide not bound to a substrate.
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http://dx.doi.org/10.1021/jacs.7b06506DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5618157PMC
September 2017

Functional, Biophysical, and Structural Characterization of Human IgG1 and IgG4 Fc Variants with Ablated Immune Functionality.

Antibodies (Basel) 2017 Sep 1;6(3). Epub 2017 Sep 1.

Janssen Research & Development, LLC, 1400 McKean Road, Spring House, Ambler, PA 19477, USA.

Engineering of fragment crystallizable (Fc) domains of therapeutic immunoglobulin (IgG) antibodies to eliminate their immune effector functions while retaining other Fc characteristics has numerous applications, including blocking antigens on Fc gamma (Fcγ) receptor-expressing immune cells. We previously reported on a human IgG2 variant termed IgG2σ with barely detectable activity in antibody-dependent cellular cytotoxicity, phagocytosis, complement activity, and Fcγ receptor binding assays. Here, we extend that work to IgG1 and IgG4 antibodies, alternative subtypes which may offer advantages over IgG2 antibodies. In several in vitro and in vivo assays, the IgG1σ and IgG4σ variants showed equal or even lower Fc-related activities than the corresponding IgG2σ variant. In particular, IgG1σ and IgG4σ variants demonstrate complete lack of effector function as measured by antibody-dependent cellular cytotoxicity, complement-dependent cytotoxicity, antibody-dependent cellular phagocytosis, and in vivo T-cell activation. The IgG1σ and IgG4σ variants showed acceptable solubility and stability, and typical human IgG1 pharmacokinetic profiles in human FcRn-transgenic mice and cynomolgus monkeys. In silico T-cell epitope analyses predict a lack of immunogenicity in humans. Finally, crystal structures and simulations of the IgG1σ and IgG4σ Fc domains can explain the lack of Fc-mediated immune functions. These variants show promise for use in those therapeutic antibodies and Fc fusions for which the Fc domain should be immunologically "silent".
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http://dx.doi.org/10.3390/antib6030012DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6698826PMC
September 2017

Functional optimization of agonistic antibodies to OX40 receptor with novel Fc mutations to promote antibody multimerization.

MAbs 2017 10 31;9(7):1129-1142. Epub 2017 Jul 31.

a Janssen Research and Development, L.L.C. , Spring House , PA , USA.

Immunostimulatory receptors belonging to the tumor necrosis factor receptor (TNFR) superfamily are emerging as promising targets for cancer immunotherapies. To optimize the agonism of therapeutic antibodies to these receptors, Fc engineering of antibodies was applied to facilitate the clustering of cell surface TNFRs to activate downstream signaling pathways. One engineering strategy is to identify Fc mutations that facilitate antibody multimerization on the cell surface directly. From the analyses of the crystal packing of IgG1 structures, we identified a novel set of Fc mutations, T437R and K248E, that facilitated antibody multimerization upon binding to antigens on cell surface. In a NF-κB reporter assay, the engineered T437R/K248E mutations could facilitate enhanced agonism of an anti-OX40 antibody without the dependence on FcγRIIB crosslinking. Nonetheless, the presence of cells expressing FcγRIIB could facilitate a boost of the agonism of the engineered antibody with mutations on IgG1 Fc, but not on the silent IgG2σ Fc. The Fc engineered antibody also showed enhanced effector functions, including antibody-dependent cell-meditated cytotoxicity, antibody-dependent cellular phagocytosis, and complement-dependent cytotoxicity, depending on the IgG subtypes. Also, the engineered antibodies showed normal FcRn binding and pharmacokinetic profiles in mice. In summary, this study elucidated a novel Fc engineering approach to promote antibody multimerization on a cell surface, which could enhance agonism and improve effector function for anti-TNFR antibodies as well as other therapeutic antibodies.
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http://dx.doi.org/10.1080/19420862.2017.1358838DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5627589PMC
October 2017

Ebola virus VP35 blocks stress granule assembly.

Virology 2017 02 23;502:73-83. Epub 2016 Dec 23.

HIV-1 RNA Trafficking Laboratory, Lady Davis Institute at the Jewish General Hospital, Montréal, Québec, Canada H3T 1E2; Department of Medicine, McGill University, Montréal, Québec, Canada H3A 0G4; Department of Microbiology and Immunology, McGill University, Montréal, Québec, Canada H3A 0G4. Electronic address:

Stress granules (SGs) are dynamic cytoplasmic aggregates of translationally silenced mRNAs that assemble in response to environmental stress. SGs appear to play an important role in antiviral innate immunity and many viruses have evolved to block or subvert SGs components for their own benefit. Here, we demonstrate that intracellular Ebola virus (EBOV) replication and transcription-competent virus like particles (trVLP) infection does not lead to SG assembly but leads to a blockade to Arsenite-induced SG assembly. Moreover we show that EBOV VP35 represses the assembly of canonical and non-canonical SGs induced by a variety of pharmacological stresses. This SG blockade requires, at least in part, the C-terminal domain of VP35. Furthermore, results from our co-immunoprecipitation studies indicate that VP35 interacts with multiple SG components, including G3BP1, eIF3 and eEF2 through a stress- and RNA-independent mechanism. These data suggest a novel function for EBOV VP35 in the repression of SG assembly.
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http://dx.doi.org/10.1016/j.virol.2016.12.012DOI Listing
February 2017

12-Month Coronary Angiography, Intravascular Ultrasound and Histology Evaluation of a Novel Fully Bioabsorbable Poly-L-Lactic Acid/Amorphous Calcium Phosphate Scaffolds in Porcine Coronary Arteries.

J Biomed Nanotechnol 2016 Apr;12(4):743-52

Our previous studies have confirmed the superior biocompatibility of the poly-L-lactic acid/amorphous calcium phosphate (PLLA/ACP) scaffolds (PowerScaffold) compared to PLLA scaffolds and their similar 6-month radial strength compared with TAXUS stents. In order to conduct further dynamic observations on the performance of the PowerScaffold after 12-month implantation compared with the TAXUS stents. Twenty PowerScaffold and 20 TAXUS were implanted in porcine coronary arteries. At 12-month follow-up, Quantitative Coronary Angiography showed that the stent reference vessel diameter (3.19 ± 0.25 mm vs. 2.75 ± 0.22 mm, p < 0.05), the mean lumen diameter (3.07 ± 0.22 mm vs. 2.70 ± 0.17 mm, p < 0.05) and the late lumen gain (0.45 ± 0.07 mm vs. 0.06 ± 0.06 mm, p < 0.01) were all significantly greater with the PowerScaffold than the TAXUS. As well, Intravascular Ultrasound showed the stent reference vessel area (7.74 ± 0.48 mm2 vs. 6.96 ± 0.51 mm2, p < 0.05), the mean stent area (7.49 ± 0.46 mm2 vs. 6.53 ± 0.47 mm2, p < 0.05) and the mean lumen area (7.22 ± 0.50 mm2 vs. 6.00 ± 0.48 mm2, p < 0.01) were all significantly greater with the PowerScaffold than the TAXUS. The luminal patency rate of the PowerScaffold significantly increased from 72.45 ± 6.84% at 1 month to 93.54 ± 8.15% at 12 months (p < 0.01) while the TAXUS stents were associated with a non-significant decreasing trend (89.44 ± 8.44% vs. 86.53 ± 8.22%). Pathology indicated the average thickness of the struts degraded by 14.25 ± 3.04 μm at 1 month, 23.39 ± 2.45 μm at 6 months and 35.54 ± 2.20 μm at 12 months. Immunohistochemical examination showed that the expression of inflammatory factors NF-κB gradually decreased from 1-month to 12-month (36.79 ± 4.78 vs. 5.79 ± 2.85, P < 0.01). As the late lumen gain of arteries implanted with the PowerScaffold increases over time with the growth of vessels, it effectively reverse the late vascular negative remodeling observed with the TAXUS stents, providing a better option for lumen restoration treatment in clinical practice.
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http://dx.doi.org/10.1166/jbn.2016.2241DOI Listing
April 2016

Extracellular histones identified in crocodile blood inhibit in-vitro HIV-1 infection.

AIDS 2016 08;30(13):2043-52

aInstitute of Medical Science, University of Toronto, Toronto bCentre for Innovation, Canadian Blood Services, Toronto cDonnelly Centre for Cellular and Biomolecular Research dDepartment of Laboratory Medicine and Pathobiology eDepartment of Medicine, University of Toronto, Toronto, Ontario, Canada. *Hannah N. Kozlowski, Eric T.L. Lai and Pierre C. Havugimana contributed equally to this study. †Stephen D.S. McCarthy and Donald R. Branch are co-senior authors.

Objective: It has been reported that crocodile blood contains potent antibacterial and antiviral properties. However, its effects on HIV-1 infection remain unknown.

Design: We obtained blood from saltwater crocodiles to examine whether serum or plasma could inhibit HIV-1 infection. We purified plasma fractions then used liquid chromatography-mass spectrometry to identify the inhibitory protein factor(s). We then analyzed the ability of recombinant proteins to recapitulate HIV-1 inhibition and determine their mechanism of action.

Methods: Crocodylus porosus plasma was tested for inhibition of Jurkat T-cell HIV-1 infection. Inhibitor(s) were purified by reverse-phase chromatography then identified by protein liquid chromatography-mass spectrometry. Anti-HIV-1 activity of purified plasma or recombinant proteins were measured by p24 enzyme-linked immunosorbent assay and luciferase readouts, and mechanism of action was determined by measuring HIV-1 RNA, cDNA and transcription (using 1G5 cells).

Results: Crocodile plasma contains potent inhibitors of HIV-1IIIB infection, which were identified as histones. Recombinant human histones H1 and H2A significantly reduced HIV-1JR-FL infection (IC50 of 0.79 and 0.45 μmol/l, respectively), whereas H4 enhanced JR-FL luciferase activity. The inhibitory effects of crocodile plasma, recombinant H1 or recombinant H2A on HIV-1 infection were during or post-viral transcription.

Conclusion: Circulating histones in crocodile blood, possibly released by neutrophil extracellular traps, are significant inhibitors of HIV-1 infection in-vitro. Extracellular recombinant histones have different effects on HIV-1 transcription and protein expression and are downregulated in HIV-1 patients. Circulating histones may be a novel resistance factor during HIV-1 infection, and peptide versions should be explored as future HIV-1 therapeutics that modulate viral transcription.
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http://dx.doi.org/10.1097/QAD.0000000000001159DOI Listing
August 2016

c-SRC protein tyrosine kinase regulates early HIV-1 infection post-entry.

AIDS 2016 Mar;30(6):849-58

aDepartment of Laboratory Medicine and Pathobiology, University of Toronto bCentre for Innovation, Canadian Blood Services, Toronto cDepartment of Medicine, University of Toronto dDivision of Advanced Diagnostics, Infection and Immunity Group, Toronto General Research Institute, Toronto, Ontario M5G 2M1, Canada.

Objective: We investigated whether HIV-1 inhibition by SRC-family kinase inhibitors is through the non-receptor tyrosine kinase pp60 (c-SRC) and its binding partner, protein tyrosine kinase 2 beta (PTK2B).

Design: CD4 T-lymphocytes were infected with R5 (JR-FL) or X4 (HXB2) HIV-1. We used SRC-family kinase inhibitors or targeted siRNA knockdown of c-SRC and PTK2B, then monitored effects on the early HIV-1 lifecycle.

Methods: Four SRC-family kinase inhibitors or targeted siRNA knockdown were used to reduce c-SRC or PTK2B protein expression. Activated CD4 T-lymphocytes were infected with recombinant, nef-deficient, or replication-competent infectious viruses. Knockdown experiments examined early infection by monitoring: luciferase activity, expression of host surface receptors, reverse transcriptase activity, p24 levels and qPCR of reverse transcripts, integrated HIV-1, and two-long terminal repeat (2-LTR) circles.

Results: All SRC-family kinase inhibitors inhibited R5 and X4 HIV-1 infection. Neither c-SRC nor PTK2B siRNA knockdown had an effect on cell surface receptors (CD4, CXCR4, and CCR5) nor on reverse transcriptase activity. However, using JR-FL both decreased luciferase activity while increasing late reverse transcripts (16-fold) and 2-LTR circles (eight-fold) while also decreasing viral integration (four-fold). With HXB2, c-SRC but not PTK2B siRNA knockdown produced similar results.

Conclusions: Our results suggest c-SRC tyrosine kinase is a major regulator of HIV-1 infection, participating in multiple stages of infection post-entry: Reduced proviral integration with increased 2-LTR circles is reminiscent of integrase inhibitors used in combination antiretroviral therapy. Decreasing c-SRC expression and/or activity provides a new target for antiviral intervention and the potential for repurposing existing FDA-approved kinase inhibitors.
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http://dx.doi.org/10.1097/QAD.0000000000001028DOI Listing
March 2016

A Rapid Screening Assay Identifies Monotherapy with Interferon-ß and Combination Therapies with Nucleoside Analogs as Effective Inhibitors of Ebola Virus.

PLoS Negl Trop Dis 2016 Jan 11;10(1):e0004364. Epub 2016 Jan 11.

Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada.

To date there are no approved antiviral drugs for the treatment of Ebola virus disease (EVD). While a number of candidate drugs have shown limited efficacy in vitro and/or in non-human primate studies, differences in experimental methodologies make it difficult to compare their therapeutic effectiveness. Using an in vitro model of Ebola Zaire replication with transcription-competent virus like particles (trVLPs), requiring only level 2 biosafety containment, we compared the activities of the type I interferons (IFNs) IFN-α and IFN-ß, a panel of viral polymerase inhibitors (lamivudine (3TC), zidovudine (AZT) tenofovir (TFV), favipiravir (FPV), the active metabolite of brincidofovir, cidofovir (CDF)), and the estrogen receptor modulator, toremifene (TOR), in inhibiting viral replication in dose-response and time course studies. We also tested 28 two- and 56 three-drug combinations against Ebola replication. IFN-α and IFN-ß inhibited viral replication 24 hours post-infection (IC50 0.038μM and 0.016μM, respectively). 3TC, AZT and TFV inhibited Ebola replication when used alone (50-62%) or in combination (87%). They exhibited lower IC50 (0.98-6.2μM) compared with FPV (36.8μM), when administered 24 hours post-infection. Unexpectedly, CDF had a narrow therapeutic window (6.25-25μM). When dosed >50μM, CDF treatment enhanced viral infection. IFN-ß exhibited strong synergy with 3TC (97.3% inhibition) or in triple combination with 3TC and AZT (95.8% inhibition). This study demonstrates that IFNs and viral polymerase inhibitors may have utility in EVD. We identified several 2 and 3 drug combinations with strong anti-Ebola activity, confirmed in studies using fully infectious ZEBOV, providing a rationale for testing combination therapies in animal models of lethal Ebola challenge. These studies open up new possibilities for novel therapeutic options, in particular combination therapies, which could prevent and treat Ebola infection and potentially reduce drug resistance.
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http://dx.doi.org/10.1371/journal.pntd.0004364DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4709101PMC
January 2016

6-Month Follow-Up of a Novel Biodegradable Drug-Eluting Stent Composed of Poly-L-Lactic Acid and Amorphous Calcium Phosphate Nanoparticles in Porcine Coronary Artery.

J Biomed Nanotechnol 2015 Oct;11(10):1819-25

Rationale: We reported previously, in porcine coronary arteries, that the novel biodegradable PowerStent Absorb paclitaxel-eluting stent had improved and sustained structural strength and functional performance at one month post-implantation.

Objective: To report the stent performance at 6-month follow-up.

Methods And Results: Six PowerStent Absorb and six TAXUS stents were randomly implanted in the left anterior descending and right coronary arteries of six Tibet miniature pigs. Quantitative coronary angiography (QCA) and intravascular ultrasound (IVUS) images were obtained at the time of implantation (T0) and at 6 months (T6). Two animals were sacrificed at T6 for histopathological evaluation. At T6, QCA showed that the mean luminal vascular diameter (mLD) between the PowerStent and the TAXUS stents were similar (2.36 ± 0.38 vs. 2.61 ± 0.31, respectively). Based on the IVUS analysis, the mLD and the mean lumen cross-sectional area (mCSA) in the PowerStent-treated arteries were similar between T0 and T6 (mLD: 2.74 ± 0.13 vs. 2.70 ± 0.20 and mCSA: 6.81 ± 0.62 mm2 vs. 6.68 ± 0.94 mm2). Histopathology showed that the PowerStent stents were well apposed to the vessel wall with no recoil, strut fracture and thrombus formation. The stents were fully covered with a layer of endothelial cells.

Conclusions: At six-month post-implantation, the PowerStent Absorb stents maintained their structural strength and functional performance. The development of restenosis was controlled, no stent thrombosis was observed and the stents were fully re-endothelialized. These results suggest the PowerStent Absorb stent is safe and effective for up to 6 months when implanted in porcine coronary arteries.
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http://dx.doi.org/10.1166/jbn.2015.2102DOI Listing
October 2015

Optimal attenuation of experimental autoimmune encephalomyelitis by intravenous immunoglobulin requires an intact interleukin-11 receptor.

PLoS One 2014 31;9(7):e101947. Epub 2014 Jul 31.

Toronto General Research Institute, University Health Network, Toronto, Ontario, Canada; Department of Immunology, University of Toronto, and Centre for Innovation, Canadian Blood Services, Toronto, Ontario, Canada; Women's College Research Institute, Toronto, Ontario, Canada.

Background: Intravenous immunoglobulin (IVIg) has been used to treat a variety of autoimmune disorders including multiple sclerosis (MS); however its mechanism of action remains elusive. Recent work has shown that interleukin-11 (IL-11) mRNAs are upregulated by IVIg in MS patient T cells. Both IVIg and IL-11 have been shown to ameliorate experimental autoimmune encephalomyelitis (EAE), an animal model of MS. The objective of this study was to determine whether the protective effects of IVIg in EAE occur through an IL-11 and IL-11 receptor (IL-11R)-dependent mechanism.

Methods: We measured IL-11 in the circulation of mice and IL-11 mRNA expression in various organs after IVIg treatment. We then followed with EAE studies to test the efficacy of IVIg in wild-type (WT) mice and in mice deficient for the IL-11 receptor (IL-11Rα-/-). Furthermore, we evaluated myelin-specific Th1 and Th17 responses and assessed spinal cord inflammation and demyelination in WT and IL-11Rα-/- mice, with and without IVIg treatment. We also examined the direct effects of mouse recombinant IL-11 on the production of IL-17 by lymph node mononuclear cells.

Results: IVIg treatment induced a dramatic surge (>1000-fold increase) in the levels of IL-11 in the circulation and a prominent increase of IL-11 mRNA expression in the liver. Furthermore, we found that IL-11Rα-/- mice, unlike WT mice, although initially protected, were resistant to full protection by IVIg during EAE and developed disease with a similar incidence and severity as control-treated IL-11Rα-/- mice, despite initially showing protection. We observed that Th17 cytokine production by myelin-reactive T cells in the draining lymph nodes was unaffected by IVIg in IL-11Rα-/- mice, yet was downregulated in WT mice. Finally, IL-11 was shown to directly inhibit IL-17 production of lymph node cells in culture.

Conclusion: These results implicate IL-11 as an important immune effector of IVIg in the prevention of Th17-mediated autoimmune inflammation during EAE.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0101947PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4117465PMC
October 2015

Hysteresis can grant fitness in stochastically varying environment.

PLoS One 2014 28;9(7):e103241. Epub 2014 Jul 28.

Department of Applied Mathematics, University College Cork, Cork, Ireland; Department of Mathematical Sciences, University of Texas at Dallas, Richardson, Texas, United States of America.

Although the existence of multiple stable phenotypes of living organisms enables random switching between phenotypes as well as non-random history dependent switching called hysteresis, only random switching has been considered in prior experimental and theoretical models of adaptation to variable environments. This work considers the possibility that hysteresis may also evolve together with random phenotype switching to maximize population growth. In addition to allowing the possibility that switching rates between different phenotypes may depend not only on a continuous environmental input variable, but also on the phenotype itself, the present work considers an opportunity cost of the switching events. This opportunity cost arises as a result of a lag phase experimentally observed after phenotype switching and stochastic behavior of the environmental input. It is shown that stochastic environmental variation results in maximal asymptotic growth rate when organisms display hysteresis for sufficiently slowly varying environmental input. At the same time, sinusoidal input does not cause evolution of memory suggesting that the connection between the lag phase, stochastic environmental variation and evolution of hysteresis is a result of a stochastic resonance type phenomenon.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0103241PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4113350PMC
November 2015

Novel biodegradable drug-eluting stent composed of poly-L-lactic acid and amorphous calcium phosphate nanoparticles demonstrates improved structural and functional performance for coronary artery disease.

J Biomed Nanotechnol 2014 Jul;10(7):1194-204

Bioabsorbable drug-eluting stents (BDES) offer multiple advantages over a permanent bare metal stent (BMS) for coronary artery disease (CAD). However, current BDES remains two major issues: inferior radial strength and biocompatibility. PowerStent Absorb BDES, fabricated by co-formulating amorphous calcium phosphate (ACP) nanoparticles with poly-L-lactic acid (PLLA/ACP, 98/2, w/w) and 2% Paclitaxel (PAX, w/w) was designed to address these issues. Two cohorts of 6 miniature pigs were each implanted with PLLA/PAX (control, 2% PAX, w/w) or PowerStent Absorb BDES. After 1 month in-vivo study, histological analyses showed significantly reduced restenosis in the PowerStent Absorb BDES cohort relative to the control cohort (44.49 +/- 410.49% vs. 64.47 +/- 16.2%, p < 0.05). Stent recoil (21.57 +/- 5.36% vs. 33.81 +/- 11.49, P < 0.05) and inflammation (3.01 +/- 0.62 vs. 4.07 +/- 0.86, P < 0.01) were also obviously decreased. From in-vitro studies, PLLA/ACP/PAX stent tube maintained significantly greater radial strength than control group during 6 months in-vitro degradation (PLLA/ACP/PAX vs. PLLA/PAX: before hydrolysis: 82.4 +/- 1.9 N vs.74.8 +/- 3.8 N; 6 weeks: 73.9 +/- 1.8 N vs. 68.0 +/- 5.3 N; 3 months: 73.5 +/- 3.4 N vs.67.2 +/- 3.8 N; 6 months: 56.3 +/- 8.1 N vs. 57.5 +/- 4.9 N). Moreover, ACP facilitated the hydrolytic degradation of PLLA compared with control one (62.6% vs. 49.8%), meanwhile, it also increased the crystallinity of PLLA (58.4% vs. 50.7%) at 6 months. From SEM observations, ACP created nanometer pores that enlarge gradually to a micrometer scale as degradation proceeds. The changes of the porosity may result in greatly promoting re-endothelialization.
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http://dx.doi.org/10.1166/jbn.2014.1868DOI Listing
July 2014

Improved biocompatibility of poly(lactic-co-glycolic acid) orv and poly-L-lactic acid blended with nanoparticulate amorphous calcium phosphate in vascular stent applications.

J Biomed Nanotechnol 2014 Jun;10(6):900-10

Biodegradable polymers used as vascular stent coatings and stent platforms encounter a major challenge: biocompatibility in vivo, which plays an important role in in-stent restenosis (ISR). Co-formulating amorphous calcium phosphate (ACP) into poly(lactic-co-glycolic acid) (PLGA) or poly-L-lactic acid (PLLA) was investigated to address the issue. For stent coating applications, metal stents were coated with polyethylene-co-vinyl acetate/poly-n-butyl methacrylate (PEVA/PBMA), PLGA or PLGA/ACP composites, and implanted into rat aortas for one and three months. Comparing with both PEVA/PBMA and PLGA groups after one month, the results showed that stents coated with PLGA/ACP had significantly reduced restenosis (PLGA/ACP vs. PEVA/PBMA vs. PLGA: 21.24 +/- 2.59% vs. 27.54 +/- 1.19% vs. 32.12 +/- 3.93%, P < 0.05), reduced inflammation (1.25 +/- 0.35 vs. 1.77 +/- 0.38 vs. 2.30 +/- 0.21, P < 0.05) and increased speed of re-endothelialization (1.78 +/- 0.46 vs. 1.17 +/- 0.18 vs. 1.20 +/- 0.18, P < 0.05). After three months, the PLGA/ACP group still displayed lower inflammation score (1.33 +/- 0.33 vs. 2.27 +/- 0.55, P < 0.05) and higher endothelial scores (2.33 +/- 0.33 vs. 1.20 +/- 0.18, P < 0.05) as compared with the PEVA/PBMA group. Moreover, for stent platform applications, PLLA/ACP stent tube significantly reduced the inflammatory cells infiltration in the vessel walls of rabbit iliac arteries relative to their PLLA cohort (NF-kappaB-positive cells: 23.31 +/- 2.33/mm2 vs. 9.34 +/- 1.35/mm2, P < 0.05). No systemic biochemical or pathological evidence of toxicity was found in either PLGA/ACP or PLLA/ACP. The co-formulation of ACP into PLGA and PLLA resulted in improved biocompatibility without systemic toxicity.
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http://dx.doi.org/10.1166/jbn.2014.1856DOI Listing
June 2014

c-Src and Pyk2 protein tyrosine kinases play protective roles in early HIV-1 infection of CD4+ T-cell lines.

J Acquir Immune Defic Syndr 2014 Jun;66(2):118-26

*Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada; †Department of Microbiology and Biochemistry, Laval University, Québec, Canada; ‡Centre for Innovation, Canadian Blood Services, Toronto, Canada; and §Division of Advanced Diagnostics, Infection and Immunity Group, Toronto General Research Institute, Toronto, Canada.

Background: During early HIV-1 infection of CD4 T-lymphocytes, many host protein tyrosine kinases become activated within minutes, including phosphoprotein pp60 (c-Src) and the focal adhesion kinase family member, proline-rich tyrosine kinase 2 (Pyk2). Whether their activation facilitates or impedes infection remains to be determined.

Methods: c-Src kinase inhibitors (SU6656, PP1, and PP2), adenovectors [wild-type and dominant-negative (DN) c-src] or siRNA (targeting c-src or pyk2) were used to inhibit, compete with or knockdown c-Src in Jurkat C, Jurkat E6-1, Hut 78 or Kit225 T-cell lines. Cells were then infected with HIV-1 luciferase reporter virus expressing VSV-G or HXB2(X4) envelope, and luciferase activity was measured after 2 days. Reverse transcriptase activity and viral cDNA were measured 1 hour after infection, whereas integrated virus was measured 12 hours after infection.

Results: Pretreating Jurkat T-cells with SU6656 led to increased VSV-G luciferase activity. In the adenovector experiments, T-cells overexpressing dominant-negative c-Src, but not wild-type c-Src, showed increased luciferase activity after VSV-G infection. siRNA knockdown of c-Src or Pyk2, followed by HXB2 infection in Jurkat T-cells, lead to increased reverse transcriptase activity, viral cDNA, integrated virus, and increased luciferase activity.

Conclusions: Pyk2 is known to interact with c-Src. Thus, Pyk2 activation that coincides with increased c-Src activity during HIV-1 infection could be responsible for c-Src activation. Reduced c-Src activation increases HIV-1 reverse transcription, integration, and/or transcription, suggesting the high c-Src activity seen early in HIV-1 infection may be a cellular response to slow or prevent early infection in CD4 T-cells.
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http://dx.doi.org/10.1097/QAI.0000000000000105DOI Listing
June 2014

Engineered protease-resistant antibodies with selectable cell-killing functions.

J Biol Chem 2013 Oct 28;288(43):30843-54. Epub 2013 Aug 28.

From Biologics Research, Janssen Research and Development, LLC, Spring House, Pennsylvania 19477.

Molecularly engineered antibodies with fit-for-purpose properties will differentiate next generation antibody therapeutics from traditional IgG1 scaffolds. One requirement for engineering the most appropriate properties for a particular therapeutic area is an understanding of the intricacies of the target microenvironment in which the antibody is expected to function. Our group and others have demonstrated that proteases secreted by invasive tumors and pathological microorganisms are capable of cleaving human IgG1, the most commonly adopted isotype among monoclonal antibody therapeutics. Specific cleavage in the lower hinge of IgG1 results in a loss of Fc-mediated cell-killing functions without a concomitant loss of antigen binding capability or circulating antibody half-life. Proteolytic cleavage in the hinge region by tumor-associated or microbial proteases is postulated as a means of evading host immune responses, and antibodies engineered with potent cell-killing functions that are also resistant to hinge proteolysis are of interest. Mutation of the lower hinge region of an IgG1 resulted in protease resistance but also resulted in a profound loss of Fc-mediated cell-killing functions. In the present study, we demonstrate that specific mutations of the CH2 domain in conjunction with lower hinge mutations can restore and sometimes enhance cell-killing functions while still retaining protease resistance. By identifying mutations that can restore either complement- or Fcγ receptor-mediated functions on a protease-resistant scaffold, we were able to generate a novel protease-resistant platform with selective cell-killing functionality.
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http://dx.doi.org/10.1074/jbc.M113.486142DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3829399PMC
October 2013

Synthesis and characterization of pullulan-polycaprolactone core-shell nanospheres encapsulated with ciprofloxacin.

J Biomed Nanotechnol 2013 Sep;9(9):1644-55

Department of Biomedical Engineering and Biotechnology, University of Massachusetts, Lowell, Massachusetts, 01854, USA.

Nanosphere-encapsulated drugs offer a means to overcome many drug delivery limitations by localizing the site of delivery and providing controlled release. This research details the synthesis and encapsulation of ciprofloxacin in pullulan-polycaprolactone (PCL) core shell nanospheres and the characterization of these materials by 1H-NMR, UV spectroscopy, dynamic light scattering (DLS) and scanning electron microscopy (SEM).1H-NMR results confirm that the pullulan-PCL grafted copolymer was successfully synthesized. UV spectroscopy showed that the ciprofloxacin loaded nanospheres contain 35-40% ciprofloxacin by weight. DLS and SEM results indicate that the loaded nanospheres are spherical in shape and approximately 142+/-12 nm in size. Under in vitro test conditions, approximately 20% of the ciprofloxacin is released in the first 4 hours, with additional release over 10 days. The nanoparticles demonstrate bioactivity against Escheria coli and do not affect the proliferation of two human cell lines. These results demonstrate the potential of pullulan-PCL core-shell nanospheres as delivery vehicles of hydrophobic drugs, including antibiotics for localized treatments applicable to a wide-range of human bacterial infections.
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http://dx.doi.org/10.1166/jbn.2013.1654DOI Listing
September 2013

Correlations between pharmacokinetics of IgG antibodies in primates vs. FcRn-transgenic mice reveal a rodent model with predictive capabilities.

MAbs 2013 May-Jun;5(3):397-405. Epub 2013 Apr 2.

Biologics Research; Janssen Research & Development, LLC; Spring House, PA USA.

Transgenic mice expressing human neonatal Fc receptor (FcRn) instead of mouse FcRn are available for IgG antibody pharmacokinetic (PK) studies. Given the interest in a rodent model that offers reliable predictions of antibody PK in monkeys and humans, we set out to test whether the PK of IgG antibodies in such mice correlated with the PK of the same antibodies in primates. We began by using a single research antibody to study the influence of: (1) different transgenic mouse lines that differ in FcRn transgene expression; (2) homozygous vs. hemizygous FcRn transgenic mice; (3) the presence vs. absence of coinjected high-dose human intravenous immunoglobulin (IVIG), and (4) the presence vs. absence of coinjected high-dose human serum albumin (HSA). Results of those studies suggested that use of hemizygous Tg32 mice (Tg32 hemi) not treated with IVIG or HSA offered potential as a predictive model for PK in humans. Mouse PK studies were then done under those conditions with a panel of test antibodies whose PK in mice and primates is not significantly affected by target binding, and for which monkey or human PK data were readily available. Results from the studies revealed significant correlations between terminal half-life or clearance values observed in the mice and the corresponding values reported in humans. A significant relationship in clearance values between mice and monkeys was also observed. These correlations suggest that the Tg32 hemi mouse model, which is both convenient and cost-effective, can offer value in predicting antibody half-life and clearance in primates.
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http://dx.doi.org/10.4161/mabs.23836DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4169033PMC
April 2015

Sustained ocular delivery of ciprofloxacin using nanospheres and conventional contact lens materials.

Invest Ophthalmol Vis Sci 2012 Mar 13;53(3):1341-52. Epub 2012 Mar 13.

Department of Biological Sciences, University of Massachusetts Lowell, Lowell, Massachusetts 01854, USA.

Purpose: To formulate conventional contact lenses that incorporate nanosphere-encapsulated antibiotic and demonstrate that the lenses provide for sustained antibacterial activity.

Methods: A copolymer composed of pullulan and polycaprolactone (PCL) was used to synthesize core-shell nanospheres that encapsulated ciprofloxacin. Bactericidal activity of the nanosphere-encapsulated ciprofloxacin (nanosphere/cipro) was tested by using liquid cultures of either Staphylococcus aureus or Pseudomonas aeruginosa. Nanosphere/cipro was then incorporated into HEMA-based contact lenses that were tested for growth inhibition of S. aureus or P. aeruginosa in liquid cultures inoculated daily with fresh bacteria. Lens designs included thin or thick lenses incorporating nanosphere/cipro and ciprofloxacin-HCl-soaked Acuvue lenses (Acuvue; Johnson & Johnson Vision Care, Inc., Jacksonville, FL).

Results: Less than 2 μg/mL of nanosphere/cipro effectively inhibited the proliferation of cultures inoculated with 10(7) or 10(8) bacteria/mL of S. aureus and P. aeruginosa, respectively. HEMA-based contact lenses polymerized with nanosphere/cipro were transparent, effectively inhibited the proliferation of greater than 10(7)/mL of bacteria added daily over 3 days of culture, and killed up to 5 × 10(9) total microbes in a single inoculation. A thicker lens design provided additional inhibition of bacterial growth for up to 96 hours.

Conclusions: Core-shell nanospheres loaded with an antibiotic can be incorporated into a conventional, transparent contact lens and provide for sustained and effective bactericidal activity and thereby provide a new drug delivery platform for widespread use in treating ocular disorders.
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http://dx.doi.org/10.1167/iovs.11-8215DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3339908PMC
March 2012

Effect of β-sheet crystalline content on mass transfer in silk films.

J Memb Sci 2011 Nov;383(1-2):44-49

Biomedical Engineering and Biotechnology Program, University of Massachusetts at Lowell, Lowell MA 01854 USA.

The material properties of silk are favorable for drug delivery due to the ability to control material structure and morphology under ambient, aqueous processing conditions. Mass transport of compounds with varying physical-chemical characteristics was studied in silk fibroin films with control of β-sheet crystalline content. Two compounds, vitamin B12 and fluorescein isothiocynate (FITC) labeled lysozyme were studied in a diffusion apparatus to determine transport through silk films. The films exhibited size exclusion phenomenon with permeability coefficients with contrasting trends with increases in β-sheet crystallinity. The size exclusion phenomenon observed with the two model compounds was characterized by contrasting trends in permeability coefficients of the films as a function of β-sheet crystallinity. The diffusivity of the compounds was examined in the context of free volume theory. Apart from the β-sheet crystallinity, size of the compound and its interactions with silk influenced mass transfer. Diffusivity of vitamin B12 was modeled to define a power law relationship with β-sheet crystallinity. The results of the study demonstrate that diffusion of therapeutic agents though silk fibroin films can be directed to match a desired rate by modulating secondary structure of the silk proteins.
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http://dx.doi.org/10.1016/j.memsci.2011.08.032DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3224987PMC
November 2011

In vitro and in vivo degradation of poly(D, L-lactide-co-glycolide)/amorphous calcium phosphate copolymer coated on metal stents.

J Biomed Mater Res A 2011 Mar 25;96(4):632-8. Epub 2011 Jan 25.

Biomedical Engineering and Biotechnology Doctoral Program, University of Massachusetts, Lowell, Massachusetts 01854, USA.

The purpose of this study was to optimize a novel biodegradable polymer for drug eluting stent (DES) applications. Degradation profiles of different poly(D,L-lactide-co-glycolide)/amorphous calcium phosphate (PLGA/ACP) composites coated on stents were studied both in vitro and in vivo for three months. For the in vitro study, stents were immersed into the phosphate buffered saline (37 °C, pH 7.4) with constant shaking. The polymer weight loss was measured weekly and morphological changes were analyzed. The results demonstrated that approximately 60% of polymer was degraded within the three-month period and there was no significant difference between the different PLGA/ACP composites. However, the composite of 50% PLGA (65/35) with 50% ACP showed a slightly faster degradation rate than other composites. Morphologically, all stent surfaces changed from a micro-porous before degradation to a corrugated solid micro-net-like structure at two months post degradation. Based on in vitro results, 65% PLGA (65/35) with 35% ACP) coated stents were selected and implanted into rat aortas (n = 12) for the in vivo study. Microscopic observation showed that no composite was found on any of the implanted stents at 12 weeks post implantation, which indicated the selected PLGA/ACP composite is desired for DES applications.
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http://dx.doi.org/10.1002/jbm.a.33016DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3291328PMC
March 2011

Trans-iliac rat aorta stenting: a novel high throughput preclinical stent model for restenosis and thrombosis.

J Surg Res 2011 Mar 9;166(1):e91-5. Epub 2010 Dec 9.

Division of Cardiothoracic Surgery, Brown Medical School, Providence, Rhode Island, USA.

Background: Currently, preclinical stent development requires elaborate large animal models, which are time consuming and expensive. We herein report a high throughput rat aorta stenting model which could provide a rapid and low-cost platform for preclinical stent development.

Methods: A total of 86 metal stents (316L stainless steel 13 mm, VasoTech, Inc.) coated with poly (D, L-lactide-co-glycolide)/amorphous calcium phosphate (PLGA/ACP) copolymer were pre-mounted on 1.5 mm × 15 mm balloon catheters and were implanted into aspirin treated Sprague-Dawley rats (500-700 g) initially using either direct placement in the abdominal aorta (group A, n = 7) or a trans-iliac approach (cut-down, group B, n = 79). The surviving rats were sacrificed at 1, 2, 4, and 12 wk post-implantation and the stented arteries were analyzed histopathologically.

Results: Four rats died in group A and nine rats died in group B within 48 h post-stent implantation (mortality: 57% versus 11%, P < 0.05). All animals that died had stent thrombosis/paralysis with visible thrombus on necropsy. Histologically, neointimal growth peaked at approximately 4 wk post-implantation.

Conclusion: This result suggests that human-sized stents can be successfully implanted into the rat aorta via iliac artery insertion with a significantly higher survival rate than trans-aorta implantation. The model system allows rapid (4-12 wk) assessment of stent biocompatibility with mortality/paralysis used as an indicator of stent thrombosis.
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http://dx.doi.org/10.1016/j.jss.2010.11.882DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3071592PMC
March 2011