Publications by authors named "Timothy Watson"

166 Publications

Outcomes of patients with ST elevation myocardial infarction in the era of second-generation drug eluting stents; five-year follow-up.

N Z Med J 2019 11 8;132(1506):34-41. Epub 2019 Nov 8.

Green Lane Cardiovascular Service, Auckland City Hospital, Auckland.

Aim: The second-generation everolimus and zotarolimus drug eluting stents (DES) have shown superiority for repeat revascularisation and safety to the first-generation devices for stable patients. However, the benefit of those devices in the setting of ST elevation myocardial infarction (STEMI) has remained questionable due to concern regarding stent thrombosis (ST) seen with the first-generation devices. We review the outcomes of patients with STEMI treated in our centre at a time when the second-generation DES became the standard of care.

Methods: All patients who presented to our institution with STEMI and underwent emergency percutaneous intervention (PCI) in 2012 with second-generation DES were identified. Case notes and electronic records were reviewed. Patients undergoing staged PCI to non-culprit lesions were excluded. Patients who died during the primary cardiac event with cardiogenic shock were also excluded.

Results: A total of 399 patients (mean age 65+/-12, 274 (76%) male) were identified. Thirty-five patients (8.7%) died during hospitalisation with cardiogenic shock and were excluded from the subsequent analysis. A further 35 patients died during follow-up. Patients received a mean of 1.15 DES. Median follow-up time was 4.7 years. Median door to reperfusion time was 90 minutes. The all-cause mortality rate for STEMI survivors was 9.6%. Cardiac mortality rate was 3.6%. Thirty-one patients (8.5%) re-presented with symptoms leading to repeat coronary angiography. In-stent restenosis (ISR) was observed only in eight patients (2.2%). The significant factors associated with re-presentation were smoking and medication non-compliance.

Conclusion: Early mortality rates following emergency PCI for STEMI remain high despite low reperfusion times. The five-year follow-up data would suggest that STEMI survivors have good outcomes with the second-generation DES.
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November 2019

Chitosan-bioglass complexes promote subsurface remineralisation of incipient human carious enamel lesions.

J Dent 2019 05 2;84:67-75. Epub 2019 Apr 2.

Centre for Oral Clinical & Translation Sciences, Faculty of Dentistry, Oral & Craniofacial Sciences, King's College London, UK; Conservative & MI Dentistry, Faculty of Dentistry, Oral & Craniofacial Sciences, King's College London, King's Health Partners, London, UK. Electronic address:

Objectives: To test the in vitro subsurface remineralisation efficacy of chitosan-bioglass complex on artificial white spot lesions.

Methods: 64 artificial enamel white spot lesions were created by acidic gel and equally separated for static and 7d pH-cycling models. In each model, samples were assigned to 4 groups: (1) bioglass application on chitosan pre-treated lesions (CB); (2) chitosan-bioglass slurry (CBS); (3) "standard" remineralisation solution (RS - positive control); (4) deionised water (NC - negative control). Before each treatment using remineralising agents, 3-minute pellicle was formed on lesions' surfaces. Mineral content changes, surface and subsurface microhardness and ultrastructure were evaluated by Raman intensity mapping, Knoop microhardness and scanning electron microscopy, respectively. Data were statistically analysed using one-way ANOVA with Tukey's test (p < 0.05 is considered as significant).

Results: Chitosan-bioglass complexing was found to exhibit greater mineral regain and recovery of surface and subsurface microhardness compared to "standard" remineralisation solution and control groups, after static and dynamic pH-cycling remineralisation for 7 days (p < 0.05). Specifically, dense precipitations with Ca/P ratios similar to that in pure hydroxyapatite (HA) were observed on surfaces and subsurfaces which filled the porosities in the dynamic pH-cycling group, leaving no prismatic enamel structure exposed.

Conclusions: Chitosan-bioglass complex is positive in promoting subsurface mineral deposition in spite of the presence of a short-term salivary pellicle. Clinical significance chitosan-bioglass complexing may provide an alternative clinical strategy in remineralising early enamel carious lesions as well as desensitizing exposed porous vital dental tissues clinically.
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http://dx.doi.org/10.1016/j.jdent.2019.03.006DOI Listing
May 2019

Platelet inhibition to target reperfusion injury trial: Rationale and study design.

Clin Cardiol 2019 Jan 17;42(1):5-12. Epub 2018 Dec 17.

The Hatter Cardiovascular Institute, Institute of Cardiovascular Science, University College London, London, UK.

Background: In ST-segment elevation myocardial infarction (STEMI) patients treated with primary percutaneous coronary intervention (PPCI), current oral P2Y12 platelet inhibitors do not provide maximal platelet inhibition at the time of reperfusion. Furthermore, administration of cangrelor prior to reperfusion has been shown in pre-clinical studies to reduce myocardial infarct (MI) size. Therefore, we hypothesize that cangrelor administered prior to reperfusion in STEMI patients will reduce the incidence of microvascular obstruction (MVO) and limit MI size in STEMI patients treated with PPCI.

Methods: The platelet inhibition to target reperfusion injury (PITRI) trial, is a phase 2A, multi-center, double-blinded, randomized controlled trial, in which 210 STEMI patients will be randomized to receive either an intravenous (IV) bolus of cangrelor (30 μg/kg) followed by a 120-minute infusion (4 μg/kg/min) or matching saline placebo, initiated prior to reperfusion (NCT03102723).

Results: The study started in October 2017 and the anticipated end date would be July 2020. The primary end-point will be MI size quantified by cardiovascular magnetic resonance (CMR) on day 3 post-PPCI. Secondary endpoints will include markers of reperfusion, incidence of MVO, MI size, and adverse left ventricular remodeling at 6 months, and major adverse cardiac and cerebrovascular events.

Summary: The aim of the PITRI trial is to assess whether cangrelor administered prior to reperfusion would reduce acute MI size and MVO, as assessed by CMR.
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http://dx.doi.org/10.1002/clc.23110DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6436500PMC
January 2019

Clinical characteristics and outcomes of South-East Asian patients with Takotsubo (stress-induced) cardiomyopathy.

Int J Cardiol Heart Vasc 2018 Dec 23;21:29-31. Epub 2018 Sep 23.

Department of Cardiology, Tan Tock Seng Hospital, Singapore.

Background: There is limited data on the natural history of Takotsubo (stress-induced) cardiomyopathy in South-East Asian patients. We aim to evaluate the clinical characteristics, predisposing factors and outcomes of patients diagnosed with Takotsubo cardiomyopathy in our region.

Methods: From January 2010 to March 2017, 98 patients were diagnosed with Takotsubo cardiomyopathy in our institution. Data were collected retrospectively on baseline clinical characteristics, presenting symptoms, precipitating factors, clinical investigations and in-hospital clinical outcomes.

Results: 82% of the patients were female. An antecedent physical stressor was more common than emotional trigger with 35% of patients having no identifiable stressor. The most common presenting symptoms were chest pain (53.1%), dyspnea (45%) and diaphoresis (18.5%).The apical variant (89%) was the most common form of Takotsubo cardiomyopathy followed by the mid-ventricular type (5.1%). The mean left ventricular ejection fraction was 35 ± 11%.In-hospital mortality due to cardiovascular causes was 4.1%. 38% of patients developed in-hospital complications. By multi-variable analysis, lower left ventricular function was an independent predictor of in-hospital complication.

Conclusion: South-East Asian patients with Takotsubo cardiomyopathy are characterised by female predominance, higher incidence of physical triggers and low cardiovascular mortality. Lower left ventricular function was an independent predictor of adverse outcomes.
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http://dx.doi.org/10.1016/j.ijcha.2018.09.007DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6154765PMC
December 2018

Evaluation of the efficacy of calcium silicate vs. glass ionomer cement indirect pulp capping and restoration assessment criteria: a randomised controlled clinical trial-2-year results.

Clin Oral Investig 2019 Apr 19;23(4):1931-1939. Epub 2018 Sep 19.

Conservative & MI Dentistry (including Endodontics), King's College London Dental, Institute at Guy's Hospital, King's Health Partners, London, UK.

Objectives: Assess calcium silicate cement (Biodentine™) vs. glass ionomer cement (Fuji IX™, control) as indirect pulp capping (IPC) materials in patients with reversible pulpitis after a 2-year follow-up. Evaluate the integrity of the overlying resin composite restorations using modified USPHS criteria and FDI criteria. Investigate the sensitivity of the modified USPHS criteria compared to the FDI criteria in the assessment of the restorations.

Materials And Methods: Seventy-two restorations (36 Biodentine™, 36 Fuji IX™) were placed randomly in 53 patients. Periapical radiographs were taken at pre-treatment (T0), 12-month (T12), and 24-month (T24) review. Restorations were assessed using the modified USPHS and FDI criteria at T12 and T24.

Results: At 24 months, 15 teeth had failed to maintain vitality (6 Biodentine™, 9 Fuji IX™). Clinical success rate of IPC for both materials was 72% and is related to the intensity of reversible pulpitis symptoms. No difference was found between T12 and T24 in the periapical (PA) radiographs and in the integrity of the resin composite restorations overlying Biodentine™ compared to Fuji IX™. There was no difference in the efficacy of the USPHS criteria compared to the FDI criteria in the assessment of the resin composite restorations.

Conclusions: Biodentine™ and Fuji IX™ were clinically effective when used as IPC materials in teeth with reversible pulpitis at T24. Resin composite restorations overlying both materials performed well at T24. Using the USPHS or FDI criteria is equally efficient at T24; however, longer term follow-up is needed to establish whether there are sensitivity differences between these assessment criteria.

Clinical Significance: Teeth with deep carious lesions approaching the pulp and with signs of reversible pulpitis can be treated successfully by indirect pulp capping using either Biodentine™ or Fuji IX™. Using the USPHS or FDI criteria to assess restorations is equally effective at 2 years.

Trial Registration: NCT02201641.
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http://dx.doi.org/10.1007/s00784-018-2638-0DOI Listing
April 2019

The Solitaire device - on the cards for retrieval of recalcitrant thrombus in acute coronary syndrome.

EuroIntervention 2019 Apr 5;14(18):e1834-e1835. Epub 2019 Apr 5.

Department of Cardiology, Tan Tock Seng Hospital, Singapore.

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http://dx.doi.org/10.4244/EIJ-D-18-00234DOI Listing
April 2019

In-vitro subsurface remineralisation of artificial enamel white spot lesions pre-treated with chitosan.

Dent Mater 2018 08 8;34(8):1154-1167. Epub 2018 May 8.

Tissue Engineering & Biophotonics Research Division, King's College London Dental Institute, King's Health Partners, London, UK; Conservative & MI Dentistry, Dental Institute, King's College London Dental Institute, King's Health Partners, London, UK. Electronic address:

Objective: To test the null hypothesis that chitosan application has no impact on the remineralisation of artificial incipient enamel white spot lesions (WSLs).

Methods: 66 artificial enamel WSLs were assigned to 6 experimental groups (n=11): (1) bioactive glass slurry, (2) bioactive glass containing polyacrylic acid (BG+PAA) slurry, (3) chitosan pre-treated WSLs with BG slurry (CS-BG), (4) chitosan pre-treated WSLs with BG+PAA slurry (CS-BG+PAA), (5) remineralisation solution (RS) and (6) de-ionised water (negative control, NC). Surface and cross-sectional Raman intensity mapping (960cm) were performed on 5 samples/group to assess mineral content. Raman spectroscopy and attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) were used to identify the type of newly formed minerals. Surface and cross-sectional Knoop microhardness were implemented to evaluate the mechanical properties after remineralisation. Surface morphologies and Ca/P ratio were observed using scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectroscopy (EDX). Data were statistically analysed using one-way ANOVA with Tukey's test.

Results: BG+PAA, CS-BG, RS presented significantly higher mineral regain compared to NC on lesion surfaces, while CS-BG+PAA had higher subsurface mineral content. Newly mineralised crystals consist of type-B hydroxycarbonate apatite. CS-BG+PAA showed the greatest hardness recovery, followed by CS-BG, both significantly higher than other groups. SEM observations showed altered surface morphologies in all experimental groups except NC post-treatment. EDX suggested a higher content of carbon, oxygen and silicon in the precipitations in CS-BG+PAA group. There was no significant difference between each group in terms of Ca/P ratio.

Significance: The null hypothesis was rejected. Chitosan pre-treatment enhanced WSL remineralisation with either BG only or with BG-PAA complexes. A further investigation using dynamic remineralisation/demineralisation system is required with regards to clinical application.
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http://dx.doi.org/10.1016/j.dental.2018.04.010DOI Listing
August 2018

The effect of dentine pre-treatment using bioglass and/or polyacrylic acid on the interfacial characteristics of resin-modified glass ionomer cements.

J Dent 2018 06 30;73:32-39. Epub 2018 Mar 30.

Tissue Engineering and Biophotonics Research Division, King's College London Dental Institute, King's College London, United Kingdom; Department of Conservative & MI Dentistry, King's College London Dental Institute, King's College London, United Kingdom.

Objective: To evaluate the effect of load-cycle aging and/or 6 months artificial saliva (AS) storage on bond durability and interfacial ultramorphology of resin-modified glass ionomer cement (RMGIC) applied onto dentine air-abraded using Bioglass 45S5 (BAG) with/without polyacrylic acid (PAA) conditioning.

Methods: RMGIC (Ionolux, VOCO) was applied onto human dentine specimens prepared with silicon-carbide abrasive paper or air-abraded with BAG with or without the use of PAA conditioning. Half of bonded-teeth were submitted to load cycling (150,000 cycles) and half immersed in deionised water for 24 h. They were cut into matchsticks and submitted immediately to microtensile bond strength (μTBS) testing or 6 months in AS immersion and subsequently μTBS tested. Results were analysed statistically by two-way ANOVA and Student-Newman-Keuls test (α = 0.05). Fractographic analysis was performed using FE-SEM, while further RMGIC-bonded specimens were surveyed for interfacial ultramorphology characterisation (dye-assisted nanoleakage) using confocal microscopy.

Results: RMGIC applied onto dentine air-abraded with BAG regardless PAA showed no significant μTBS reduction after 6 months of AS storage and/or load cycling (p > 0.05). RMGIC-dentine interface showed no sign of degradation/nanoleakage after both aging regimens. Conversely, interfaces created in PAA-conditioned SiC-abraded specimens showed significant reduction in μTBS (p < 0.05) after 6 months of storage and/or load cycling with evident porosities within bonding interface.

Conclusions: Dentine pre-treatment using BAG air-abrasion might be a suitable strategy to enhance the bonding performance and durability of RMGIC applied to dentine. The use of PAA conditioner in smear layer-covered dentine may increase the risk of degradation at the bonding interface.

Clinical Significance: A combined dentine pre-treatment using bioglass followed by PAA may increase the bond strength and maintain it stable over time. Conversely, the use of PAA conditioning alone may offer no significant contribute to the immediate and prolonged bonding performance.
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http://dx.doi.org/10.1016/j.jdent.2018.03.014DOI Listing
June 2018

Cellular differentiation, bioactive and mechanical properties of experimental light-curing pulp protection materials.

Dent Mater 2018 06 16;34(6):868-878. Epub 2018 Mar 16.

Tissue Engineering and Biophotonics Research Division, King's College London Dental Institute, King's Health Partners, London, UK; Department of Conservative & MI Dentistry, King's College London Dental Institute, King's Health Partners, London, UK.

Objective: Materials for pulp protection should have therapeutic properties in order to stimulate remineralization and pulp reparative processes. The aim of this study was to evaluate the mechanical properties, biocompatibility, cell differentiation and bioactivity of experimental light-curable resin-based materials containing bioactive micro-fillers.

Methods: Four calcium-phosphosilicate micro-fillers were prepared and incorporated into a resin blend: 1) Bioglass 45S5 (BAG); 2) zinc-doped bioglass (BAG-Zn); 3) βTCP-modified calcium silicate (β-CS); 4) zinc-doped β-CS (β-CS-Zn). These experimental resins were tested for flexural strength (FS) and fracture toughness (FT) after 24h and 30-day storage in simulated body fluid (SBF). Cytotoxicity was evaluated using MTT assay, while bioactivity was evaluated using mineralization and gene expression assays (Runx-2 & ALP).

Results: The lowest FS and FT at 24h was attained with β-CS resin, while all the other tested materials exhibited a decrease in FS after prolonged storage in SBF. β-CS-Zn maintained a stable FT after 30-day SBF aging. Incorporation of bioactive micro-fillers had no negative effect on the biocompatibility of the experimental materials tested in this study. The inclusion of zinc-doped fillers significantly increased the cellular remineralization potential and expression of the osteogenic genes Runx2 and ALP (p<0.05).

Significance: The innovative materials tested in this study, in particular those containing β-CS-Zn and BAG-Zn may promote cell differentiation and mineralization. Thus, these materials might represent suitable therapeutic pulp protection materials for minimally invasive and atraumatic restorative treatments.
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http://dx.doi.org/10.1016/j.dental.2018.02.008DOI Listing
June 2018

Remineralisation of enamel white spot lesions pre-treated with chitosan in the presence of salivary pellicle.

J Dent 2018 05 21;72:21-28. Epub 2018 Feb 21.

Tissue Engineering & Biophotonics Research Division, King's College London Dental Institute, King's Health Partners, London, UK; Conservative & MI Dentistry, Dental Institute, King's College London Dental Institute, King's Health Partners, London, UK. Electronic address:

Objective: To investigate the remineralisation of chitosan pre-treated enamel white spot lesions (WSLs) by bioglass in the presence of the pellicle layer.

Methods: 50 artificial enamel white spot lesions were created by acidic gel. Two lesions were used to investigate the formation of the pellicle layer by treating with human whole saliva for 3 min. 48 lesions were assigned to 6 experimental groups (n = 8): (1) bioactive glass slurry, (2) bioactive glass containing polyacrylic acid (BG + PAA) slurry, (3) chitosan pre-treated WSLs with BG slurry (CS-BG), (4) chitosan pre-treated WSLs with BG + PAA slurry (CS-BG + PAA), (5) "standard" remineralisation solution (RS) and (6) de-ionised water (negative control, NC). Remineralisation was carried out using a pH-cycling model for 7 days. Before each treatment using remineralising agents, 3-min pellicle was formed on lesions' surfaces. Mineral content changes, surface and subsurface microhardness and ultrastructure were evaluated by Raman intensity mapping, Knoop microhardness and scanning electron microscopy, respectively. Data were statistically analysed using one-way ANOVA with Tukey's test (p < 0.05 is considered as significant).

Results: Despite the heterogeneously formed pellicle layer, all groups showed an increase in surface mineral content after pH-cycling. Chitosan pre-treatment enhanced the subsurface remineralisation of WSLs using bioglass as both pre-treated groups showed greater surface and subsurface microhardness compared to NC. CS-BG exhibited denser subsurface structure than BG, while in CS-BG + PAA the crystals were bigger in size but resemble more enamel-like compared to BG + PAA as shown in SEM observations. Remineralisation of RS was limited to the surface as no significant subsurface changes of mechanical properties and structure were found.

Conclusions: Chitosan pre-treatment can enhance WSL remineralisation with bioglass biomaterials when a short-term salivary pellicle is present. A further investigation using a long-term pH-cycling model with mature pellicle is suggested with regards to clinical application.

Clinical Significance: Chitosan pre-treatment has the potential in clinical application to remineralise subsurface lesions to achieve lesion consolidation.
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http://dx.doi.org/10.1016/j.jdent.2018.02.004DOI Listing
May 2018

Long and short of optimal stent design.

Open Heart 2017;4(2):e000680. Epub 2017 Oct 30.

Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand.

The ideal stent must fulfil a broad range of technical requirements. Stents must be securely crimped onto the delivery balloon and, in this form, must have a low profile and be sufficiently flexible to facilitate deliverability to the lesion site without distortion or displacement. Following expansion, stents must exert sufficient radial force on the vessel wall to overcome lesion resistance and elastic recoil. To achieve an optimal lumen diameter, the lesion must be uniformly and adequately scaffolded, with minimal tissue prolapse between struts but without compromising side-branch access. Furthermore, the deployed stent must conform to the vessel curvature to minimise vessel distortion, particularly at the stent edges. Radio-opacity is also important to guide safe positioning, adequate deployment and postdilataion and to permit assessment of optimal stent expansion. Equally though, the stent lumen must also be sufficiently visible to allow radiographic assessment of flow dynamics and restenosis. Efforts to optimise one characteristic of stent design may have detrimental effects on another. Thus, currently available stents all reflect a compromise between competing desirable features and have subtle differences in their performance characteristics. Striving to achieve stents with optimal deliverability, conformability and radial strength led to a reduction in longitudinal strength. The importance of this parameter was highlighted by complications occurring in the real-world setting where percutaneous coronary intervention is often undertaken in challenging anatomy. This review focuses on aspects of stent design relevant to longitudinal strength.
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http://dx.doi.org/10.1136/openhrt-2017-000680DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5663262PMC
October 2017

Clinical characteristics, risk factors and outcomes of South-East Asian patients with acute pulmonary embolism.

Int J Cardiol 2017 Dec 22;249:431-433. Epub 2017 Sep 22.

Department of Cardiology, Tan Tock Seng Hospital, Singapore. Electronic address:

Background: The clinical features of acute PE have not been well studied in South-East Asia. We therefore sought to evaluate the clinical characteristics, risk factors and outcomes of patients diagnosed with acute pulmonary embolism (PE) in our region.

Methods: From January 2008 to March 2013, 343 patients were admitted to our tertiary institution with acute PE. Data were collected retrospectively on baseline clinical characteristics, presenting signs and symptoms, results of electrocardiographic and imaging studies, therapeutic modality and hospital course.

Results: 91% of the patients presented with submassive PE. 6.1% of patients had saddle PE. The most common presenting symptom was dyspnea (72.3%) followed by chest pain (12.8%), hemoptysis (2.6%), syncope (2.6%) and cardiovascular collapse (1.2%). Risk factors for PE were idiopathic cause (33.5%), immobilization (21%), malignancy (6.1%) and hypercoagulable state (2.9%). The overall in-hospital mortality was 5%. Factors associated with mortality were massive PE, tachycardia at presentation, right ventricular dysfunction and cardiogenic shock. Bleeding complications occurred in 10.2% of patients (major bleeding in 3.5%).

Conclusion: Acute PE in the South-East Asian patients is associated with an overall mortality rate of 5%. The bleeding complications from treatment are also high.
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http://dx.doi.org/10.1016/j.ijcard.2017.09.173DOI Listing
December 2017

Causes of delay in door-to-balloon time in south-east Asian patients undergoing primary percutaneous coronary intervention.

PLoS One 2017 21;12(9):e0185186. Epub 2017 Sep 21.

Department of Cardiology, Tan Tock Seng Hospital, Singapore, Singapore.

Objective: To evaluate causes and impact of delay in the door-to-balloon (D2B) time for patients undergoing primary percutaneous coronary intervention (PPCI).

Subjects And Methods: From January 2009 to December 2012, 1268 patients (86% male, mean age of 58 ± 12 years) presented to our hospital for ST-elevation myocardial infarction (STEMI) and underwent PPCI. They were divided into two groups: Non-delay defined as D2B time ≤ 90 mins and delay group defined as D2B time > 90 mins. Data were collected retrospectively on baseline clinical characteristics, mode of presentation, angiographic findings, therapeutic modality and inhospital outcome.

Results: 202 patients had delay in D2B time. There were more female patients in the delay group. They were older and tend to self-present to hospital. They were less likely to be smokers and have a higher prevalence of prior MI. The incidence of posterior MI was higher in the delay group. They also had a higher incidence of triple vessel disease. The 3 most common reasons for D2B delay was delay in the emergency department (39%), atypical clinical presentation (37.6%) and unstable medical condition requiring stabilisation/computed tomographic imaging (26.7%). The inhospital mortality was numerically higher in the delay group (7.4% versus 4.8%, p = 0.12).

Conclusions: Delay in D2B occurred in 16% of our patients undergoing PPCI. Several key factors for delay were identified and warrant further intervention.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0185186PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5608363PMC
October 2017

Left ventricular pseudoaneurysm.

J Geriatr Cardiol 2017 Jan;14(1):78-80

Department of Cardiothoracic Surgery, National University Heart Centre, Singapore.

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http://dx.doi.org/10.11909/j.issn.1671-5411.2017.01.010DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5329737PMC
January 2017

An in vitro investigation of pre-treatment effects before fissure sealing.

Int J Paediatr Dent 2017 Nov 10;27(6):514-522. Epub 2017 Feb 10.

Paediatric Dentistry, Population and Patient Health, King's College London Dental Institute, London, UK.

Background: Fissure sealants prevent occlusal caries in permanent molars. Enamel preparation methods are used before fissure sealing.

Aims: To investigate effects of bioglass air-abrasion pre-treatment with and without an adhesive, on fissure enamel of permanent teeth, with respect to etchability, microleakage and microtensile bond strength.

Design: Half of the occlusal surfaces of 50 extracted premolars underwent bioglass air-abrasion. Dye was applied to the entire occlusal surface. Photographs were taken to score etched surface by dye uptake. Adhesive was applied to 25 of the bioglass-treated areas and all teeth were fissure sealed, sectioned, and evaluated using confocal microscopy. Buccal and lingual surfaces of a further eight premolars were acid-etched and randomly received: air-abrasion, adhesive, both, or none before sealant application for microtensile bond strength measurement in half of the samples immediately and half following 6 months of water immersion.

Results: Linear mixed models and multinomial logistic regression were used (P = 0.05). Bioglass air-abrasion significantly improved enamel etchability and reduced microleakage. The addition of an adhesive made no difference to either microleakage or microtensile bond strength. The combination of bioglass abrasion and adhesive led to more cohesive, rather than adhesive, failure.

Conclusions: Bioglass air-abrasion improved enamel etchability and reduced microleakage irrespective of the adhesive use but neither pre-treatment affected the microtensile bond strength.
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http://dx.doi.org/10.1111/ipd.12290DOI Listing
November 2017

Influence of bioactive particles on the chemical-mechanical properties of experimental enamel resin infiltrants.

Clin Oral Investig 2017 Jul 12;21(6):2143-2151. Epub 2016 Nov 12.

Biomaterials and Minimally Invasive Dentistry-Departamento de Odontologia, Facultad de Ciencias de la Salud, Universidad CEU, Cardenal Herrera, C/Del Pozo s/n, Alfara del Patriarca, Valencia, Spain.

Objective: This study aimed at evaluating the chemophysical properties of experimental resin infiltrants (ERIs) doped with different bioactive particles.

Methods: A control resin infiltrant (CR) was formulated using triethylene glycol dimethacrylate (TEGDMA) and ethoxylated bisphenol A dimethacrylate (BisEMA). Moreover, five experimental ERIs were also created by incorporating the following bioactive fillers (10 wt%) into the CR: hydroxyapatite (Hap), amorphous calcium phosphate (ACP), zinc-polycarboxylated bioactive glass (BAG-Zn), bioactive glass 45S5 (BAG 45S5), and calcium silicate modified with beta tricalcium phosphate (β-TCP). ICON® resin infiltrant was also used as control. All the ERIs used in this study were assessed for degree of conversion (DC), Knoop microhardness (KHN), softening ratio (SR), tensile cohesive strength (TCS), modulus of elasticity (E-modulus), water sorption (WS), and solubility (SL). Data were subjected to ANOVA and Tukey's test (α = 5%).

Results: ICON® presented the lowest DC, KHN, TCS, E-modulus, and SR. Incorporation of bioactive fillers into CR caused significant increase in the KHN. Conversely, no significant effect was observed on DC, TCS, and E-modulus. The resin infiltrant containing Hap showed a significant increase in softening ratio, while, ICON® presented the highest WS and SL. The WS of ACP-doped resin infiltrant was significantly higher than that of the Hap-doped infiltrant. The SL of the ACP-doped infiltrant was higher than CR BAG-Zn or BAG 45S5.

Conclusion: The incorporation of bioactive particles into experimental resin infiltrants can improve the chemomechanical properties and reduce water sorption and solubility.

Clinical Relevance: Resin infiltrants doped with bioactive particles may improve the long-term performance of the treatment of white-spot lesions.
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http://dx.doi.org/10.1007/s00784-016-2005-yDOI Listing
July 2017

Drug-Coated Balloons: A Safe and Effective Alternative to Drug-Eluting Stents in Small Vessel Coronary Artery Disease.

J Interv Cardiol 2016 Oct 30;29(5):454-460. Epub 2016 Aug 30.

Tan Tock Seng Hospital, Singapore.

Background: Drug-coated balloons (DCB) have been used to treat de novo small vessel coronary disease (SVD), with promising results and shorter dual antiplatelet therapy (DAPT) duration compared to drug-eluting stents (DES). We compared safety and effectiveness of the two treatments at 1 year.

Methods: We reviewed 3,613 angioplasty cases retrospectively from 2011 to 2013 and identified 335 patients with SVD treated with device diameter of ≤2.5 mm. DCB-only angioplasty was performed in 172 patients, whereas 163 patients were treated with second-generation DES.

Results: DCB patients had smaller reference vessel diameter (2.22 ± 0.30 vs. 2.44 ± 0.19 mm, P < 0.001) and received smaller devices (median diameter 2.25 vs. 2.50 mm, P < 0.001) compared to the DES group. DES-treated vessels had larger acute lumen gain (1.71 ± 0.48 mm) than DCB (1.00 ± 0.53 mm, P < 0.001). Half the patients had diabetes mellitus. While there were more patients presenting with acute coronary syndrome (ACS) in the DCB group (77.9% vs. 62.2%, P = 0.013), they received shorter DAPT (7.4 ± 4.7 vs. 11.8 ± 1.4 months, P < 0.001) than the DES group. The 1-year composite major adverse cardiac event rate was 11.6% in the DCB arm and 11.7% in the DES arm (P = 1.000), with target lesion revascularization rate of 5.2% and 3.7%, respectively, (P = 0.601).

Conclusions: In this high-risk cohort of patients, DCB-only angioplasty delivered good clinical outcome at 1 year. The results were comparable with DES-treated patients, but had the added benefit of a shorter DAPT regime.
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http://dx.doi.org/10.1111/joic.12333DOI Listing
October 2016

Angiographic, optical coherence tomography and histology findings from combination of a drug-coated balloon with an everolimus-eluting stent in a porcine model.

Int J Cardiol 2016 Nov 18;223:665-668. Epub 2016 Aug 18.

Wakayama Medical University, Kimiidera 811-1, Wakayama 641-8509, Japan.

Background: We designed a porcine model to compare the angiographic, optical coherence tomography (OCT) and histological findings of implanting an everolimus-eluting stent (EES) in the same segment of the coronary artery pre-treated with a drug-coating balloon (DCB; paccocath as carrier) with EES alone and DCB plus a bare metal stent (BMS).

Methods: Seven female swine averaging 46.0±2.4kg were treated by random assignment as follows: DCB followed by EES; DCB followed by BMS; and EES alone. Quantitative coronary angiography (QCA) and OCT were carried out post-implantation and repeated after 28±1days.

Results: All arteries remained patent and demonstrated no sign of thrombus formation. There was no significant difference at 1month between the treatment groups in lumen loss (0.64±0.43, 0.44±0.43 and 0.33±0.28mm for EES, DCB/EES and DCB/BMS respectively, p=0.37) and binary restenosis (6.86 (2.91-9.12), 4.93 (-1.53-10.7) and 4.18 (3.27-10.2)% respectively, p=0.87). OCT found mean neointimal thickness of 0.15±0.09, 0.07±0.03 and 0.08±0.03mm (p=0.05) for EES, DCB/EES and DCB/BMS respectively. Endothelial strut coverage was 92.3±5.5, 85.4±8.6 and 89.1±8.9% (p=0.05) and mean neointimal area was 1.06±0.42, 0.95±0.24 and 1.20±0.28mm (p=0.09) respectively. Inflammation score was similar between the three groups: 0.20 (0.20-0.28), 0.30 (0.22-0.48), 0.30 (0.20-0.38) for EES, DCB/EES and DCB/BMS respectively (p=0.14) and there were no differences in fibrin deposition.

Conclusions: The combination of DCB with EES appeared to be safe and effective. Using EES to bail out suboptimal DCB therapy appeared to be safe and effective in this porcine model.
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http://dx.doi.org/10.1016/j.ijcard.2016.08.268DOI Listing
November 2016

The Selection and Control of Starting Materials Should be Governed by Science and Risk-Based Approaches.

AAPS J 2017 01 3;19(1):1-3. Epub 2016 Aug 3.

Regulatory CMC; AstraZeneca | Global Regulatory Affairs, ROS17, Mill Court, Silk Road Business Park, Charter Way, Macclesfield, Cheshire, SK10 2NA, UK.

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http://dx.doi.org/10.1208/s12248-016-9960-8DOI Listing
January 2017

Root dentine and endodontic instrumentation: cutting edge microscopic imaging.

Interface Focus 2016 Jun;6(3):20150113

Tissue Engineering and Biophotonics Division , King's College London Dental Institute , Floor 17, Guy's Tower, Guy's Hospital, London SE1 9RT , UK.

Cutting of the dental hard tissues is an integral part of restorative dentistry. Cutting of the root dentine is also needed in preparation prior to endodontic treatment, with significant commercial investment for the development of flexible cutting instruments based around nickel titanium (NiTi) alloys. This paper describes the evolution of endodontic cutting instruments, both in materials used, e.g. the transition from stainless steel to NiTi, and the design of the actual instruments themselves and their method of activation-by hand or motor driven. We have been examining tooth-cutting interactions microscopically for over 25 years using a variety of microscopic techniques; in particular, video-rate confocal microscopy. This has given a unique insight into how many of the procedures that we take for granted are achieved in clinical practice, by showing microscopic video images of the cutting as it occurs within the tooth. This technology has now been extended to allow imaging of the endodontic instrument and the root canal wall for the first time. We are able to image dentine distortion and crack propagation during endodontic filing of the root canal space. We are also able to visualize the often claimed, but seldom seen action of contemporary endodontic instruments.
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http://dx.doi.org/10.1098/rsfs.2015.0113DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4843625PMC
June 2016

Effect of placing intentionally high restorations: Randomized clinical trial.

J Dent 2016 Feb 24;45:26-31. Epub 2015 Nov 24.

Primary Dental Care, King's College London Dental Institute, London, United Kingdom. Electronic address:

Objective: The aim of this study was to examine the behavior of posterior teeth restored with single-tooth restorations with intentionally high occlusal contacts.

Methods: Consent was obtained from 17 patients who were seen a total of 5 times over 3.5 years. The restorations placed were all full occlusal coverage gold restorations. Tooth mobility was recorded using the Periotest device and tooth movement was determined from impressions and 3D imaging. Patients were randomly assigned into two groups, the control group which received restorations with no intentional increase of the occlusal vertical dimension; or the treatment group where they received intentionally high restorations in 0.5mm supraocclusion.

Results: Statistical analysis showed no significant difference in mobility between visits for both the control and the treatment groups while a significant dependency and difference in tooth movement was observed between the subjects of the two groups. Most patients from the treatment group reported discomfort but no pain for the first 7-10 days after the restoration was fitted, which subsided over a period of couple of weeks. At review, 3 years later, no mobility or additional movement was observed.

Conclusions: Cementation of an intentionally high single-tooth restoration causes no increase in tooth mobility while occlusal adaptation re-establishes and restores the occlusal plane.
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http://dx.doi.org/10.1016/j.jdent.2015.11.006DOI Listing
February 2016

Unruptured Sinus of Valsalva Aneurysm with Right Ventricular Outflow Tract Obstruction and Supracristal Ventricular Septal Defect: A Rare Case.

Tex Heart Inst J 2015 Oct 1;42(5):462-4. Epub 2015 Oct 1.

Unruptured right sinus of Valsalva aneurysm that causes severe obstruction of the right ventricular outflow tract is extremely rare. We describe the case of a 47-year-old woman who presented with exertional dyspnea. Upon investigation, we discovered an unruptured right sinus of Valsalva aneurysm with associated right ventricular outflow tract obstruction and a supracristal ventricular septal defect. To our knowledge, only 2 such cases have previously been reported in the medical literature. Although treatment of unruptured sinus of Valsalva aneurysm remains debatable, surgery should be considered for extremely large aneurysms or for progressive enlargement of the aneurysm on serial evaluation. Surgery was undertaken in our patient because there was clear evidence of right ventricular outflow tract obstruction, right-sided heart dilation, and associated exertional dyspnea.
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http://dx.doi.org/10.14503/THIJ-14-4483DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4591888PMC
October 2015

Evaluation of Previously Cannulated Radial Arteries as Patent Coronary Artery Bypass Conduits.

Tex Heart Inst J 2015 Oct 1;42(5):448-9. Epub 2015 Oct 1.

In coronary artery bypass grafting, good-quality conduits are needed to maximize the potential for long-term patency. Revascularization has traditionally been achieved with use of the saphenous vein and the internal thoracic arteries. In recent years, total arterial revascularization with use of the radial arteries has been promoted. Meanwhile, use of the transradial approach for coronary angiography has also increased. The long-term effects of previous cannulation in radial artery bypass grafts are not known. Therefore, we used multidetector computed tomographic angiography to investigate radial-artery graft patency in a small series of patients who had undergone transradial angiography. We found a high patency rate, and we discuss those findings here.
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http://dx.doi.org/10.14503/THIJ-14-4671DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4591884PMC
October 2015

Profound sustained hypotension following renal denervation: a dramatic success?

Arq Bras Cardiol 2015 Aug;105(2):202-4

Departamento de Cardiologia, Medical Center, Universidade Malaya, Kuala Lumpur, MY.

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http://dx.doi.org/10.5935/abc.20150100DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4559132PMC
August 2015

An Analysis of Spatial Clustering of Stroke Types, In-hospital Mortality, and Reported Risk Factors in Alberta, Canada, Using Geographic Information Systems.

Can J Neurol Sci 2015 Sep 16;42(5):299-309. Epub 2015 Jul 16.

4Department of Clinical Neurosciences,Community Health Sciences,Hotchkiss Brain Institute,University of Calgary,Calgary,Alberta,Canada.

Background: Despite advances in the quality and delivery of stroke care, regional disparities in stroke incidence and outcome persist. Spatial analysis using geographic information systems (GIS) can assist in identifying high-risk populations and regional differences in efficacy of stroke care. The aim of this study was to identify and locate geographic clusters of high or low rates of stroke, risk factors, and in-hospital mortality across a provincial health care network in Alberta, Canada.

Methods: This study employed a spatial epidemiological approach using population-based hospital administrative data. Getis-Ord Gi* and Spatial Scan statistics were used to identify and locate statistically significant "hot" and "cold" spots of stroke occurrence by type, risk factors, and in-hospital mortality.

Results: Marked regional variations were found. East central Alberta was a significant hot spot for ischemic stroke (relative risk [RR] 1.43, p<0.001), transient ischemic attack (RR 2.25, p<0.05), and in-hospital mortality (RR 1.50, p<0.05). Hot spots of intracerebral hemorrhage (RR 1.80, p<0.05) and subarachnoid hemorrhage (RR 1.64, p<0.05) were identified in a major urban centre. Unexpectedly, stroke risk factor hot spots (RR 2.58, p<0.001) were not spatially associated (did not overlap) with hot spots of ischemic stroke, transient ischemic attack, or in-hospital mortality.

Conclusions: Integration of health care administrative data sets with geographic information systems contributes valuable information by identifying the existence and location of regional disparities in the spatial distribution of stroke occurrence and outcomes. Findings from this study raise important questions regarding why regional differences exist and how disparities might be mitigated.
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http://dx.doi.org/10.1017/cjn.2015.241DOI Listing
September 2015
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