Lithium Disilicate Ceramic Endocrown Biomechanical Response According to Different Pulp Chamber Extension Angles and Filling Materials

The purpose of this study is to evaluate the effect of pulp chamber extension angles and filling material mechanical properties on the biomechanical response of a ceramic endocrown. A 3D model of maxillary molar that underwent endodontically treatment was exported to computer aided design software to conduct finite element analysis (FEA). The endocrown model was modified considering different pulp chamber extension angles (right angle; 6°, 12° and 18° of axial divergence). The solids were imported into the computer aided engineering software in Standard for the Exchange of Product Data (STEP) format. Nine different filling materials were simulated to seal the orifice of the root canal system under each endocrown restoration (resin composite, bulk-fill resin composite, alkasite, flowable resin composite, glass ionomer cement, autocured resin-reinforced glass ionomer cement, resin cement, bulk-fill flowable resin composite, zinc oxide cement), totaling 36 models. An axial load (300 N) was applied at the occlusal surface. Results were determined by colorimetric graphs of von-Misses stress (VMS) and Maximum Principal Stress (MPS) on tooth, cement layer, and endocrown restorations. VMS distribution showed a similar pattern between the models, with more stress at the load region for the right-angled endocrowns. The MPS showed that the endocrown intaglio surface and cement layer showed different mechanical responses with different filing materials and pulp chamber angles. The stress peaks plotted in the dispersion plot showed that the filling material stiffness is proportional to the stress magnitude in the endocrown, cement layer and tooth adhesive surface. In addition, the higher the pulp chamber preparation angle, the higher the stress peak in the restoration and tooth, and the lower the stress in the cement layer. Therefore, 6° and 12° pulp chamber angles showed more promising balance between the stresses of the adhesive interface structures. Under the conditions of this study, rigid filling materials were avoided to seal the orifice of root canal system when an endocrown restoration was planned as rehabilitation. In addition, the pulp chamber axial walls were prepared between 6° and 12° of divergence to balance the stress magnitude in the adhesive interface for this treatment modality.     

Risk Stratification Among Survivors of Cardiac Arrest Considered for Coronary Angiography

BackgroundThe American College of Cardiology Interventional Council published consensus-based recommendations to help identify resuscitated cardiac arrest patients with unfavorable clinical features in whom invasive procedures are unlikely to improve survival.ObjectivesThis study sought to identify how many unfavorable features are required before prognosis is significantly worsened and which features are most impactful in predicting prognosis.MethodsUsing the INTCAR (International Cardiac Arrest Registry), the impact of each proposed “unfavorable feature” on survival to hospital discharge was individually analyzed. Logistic regression was performed to assess the association of such unfavorable features with poor outcomes.ResultsSeven unfavorable features (of 10 total) were captured in 2,508 patients successfully resuscitated after cardiac arrest (ongoing cardiopulmonary resuscitation and noncardiac etiology were exclusion criteria in our registry). Chronic kidney disease was used in lieu of end-stage renal disease. In total, 39% survived to hospital discharge. The odds ratio (OR) of survival to hospital discharge for each unfavorable feature was as follows: age >85 years OR: 0.30 (95% CI: 0.15 to 0.61), time-to-ROSC >30 min OR: 0.30 (95% CI: 0.23 to 0.39), nonshockable rhythm OR: 0.39 (95% CI: 0.29 to 0.54), no bystander cardiopulmonary resuscitation OR: 0.49 (95% CI: 0.38 to 0.64), lactate >7 mmol/l OR: 0.50 (95% CI: 0.40 to 0.63), unwitnessed arrest OR: 0.58 (95% CI: 0.44 to 0.78), pH <7.2 OR: 0.78 (95% CI: 0.63 to 0.98), and chronic kidney disease OR: 0.96 (95% CI: 0.70 to 1.33). The presence of any 3 or more unfavorable features predicted <40% survival. Presence of the 3 strongest risk factors (age >85 years, time-to-ROSC >30 min, and non-ventricular tachycardia/ventricular fibrillation) together or ≥6 unfavorable features predicted a ≤10% chance of survival to discharge.ConclusionsPatients successfully resuscitated from cardiac arrest with 6 or more unfavorable features have a poor long-term prognosis. Delaying or even forgoing invasive procedures in such patients is reasonable.     

Paediatric Patients with Coeliac Disease on a Gluten-Free Diet: Nutritional Adequacy and Macro- and Micronutrient Imbalances

Purpose of Review

A strict, lifelong gluten-free diet is the cornerstone for management of coeliac disease. Elimination of gluten from the diet may be associated with nutritional imbalance; however, the completeness of this diet in energy and macro- and micronutrients in children is not well described. Understanding the nutritional adequacy of the gluten-free diet in children during this critical period of growth and development when dietary intake is strongly influential is important.

Recent Findings

Children, regardless of whether they have eliminated gluten from their diet, have a tendency to consume excess fat and insufficient fibre, iron, vitamin D and calcium, compared to recommendations. In the context of a gluten-free diet, these imbalances may be worsened or have more significant consequences. Paediatric studies have demonstrated that intakes of folate, magnesium, zinc and selenium may decrease on a gluten-free diet.

Summary

Nutritional inadequacies may be risks of a gluten-free diet in a paediatric population. The potential implications of these inadequacies, both short and long term, remain unclear and warrant further investigation and clarification.

     

Improving Dengue Diagnostics and Management Through Innovative Technology

Purpose of Review

Dengue continues to be a major global public health threat. Symptomatic infections can cause a spectrum of disease ranging from a mild febrile illness to severe and potentially life-threatening manifestations. Management relies on supportive treatment with careful fluid replacement. The purpose of this review is to define the unmet needs and challenges in current dengue diagnostics and patient monitoring and outline potential novel technologies to address these needs.

Recent Findings

There have been recent advances in molecular and point-of-care (POC) diagnostics as well as technologies including wireless communication, low-power microelectronics, and wearable sensors that have opened up new possibilities for management, clinical monitoring, and real-time surveillance of dengue.

Summary

Novel platforms utilizing innovative technologies for POC dengue diagnostics and wearable patient monitors have the potential to revolutionize dengue surveillance, outbreak response, and management at population and individual levels. Validation studies of these technologies are urgently required in dengue-endemic areas.

     

Methylene Blue Counteracts H<Subscript>2</Subscript>S-Induced Cardiac Ion Channel Dysfunction and ATP Reduction

We have previously demonstrated that methylene blue (MB) counteracts the effects of hydrogen sulfide (H₂S) cardiotoxicity by improving cardiomyocyte contractility and intracellular Ca²⁺ homeostasis disrupted by H₂S poisoning. In vivo, MB restores cardiac contractility severely depressed by sulfide and protects against arrhythmias, ranging from bundle branch block to ventricular tachycardia or fibrillation. To dissect the cellular mechanisms by which MB reduces arrhythmogenesis and improves bioenergetics in myocytes intoxicated with H₂S, we evaluated the effects of H₂S on resting membrane potential (E_m), action potential (AP), Na⁺/Ca²⁺ exchange current (I_NaCa), depolarization-activated K⁺ currents and ATP levels in adult mouse cardiac myocytes and determined whether MB could counteract the toxic effects of H₂S on myocyte electrophysiology and ATP. Exposure to toxic concentrations of H₂S (100 µM) significantly depolarized E_m, reduced AP amplitude, prolonged AP duration at 90% repolarization (APD₉₀), suppressed I_NaCa and depolarization-activated K⁺ currents, and reduced ATP levels in adult mouse cardiac myocytes. Treating cardiomyocytes with MB (20 µg/ml) 3 min after H₂S exposure restored E_m, APD₉₀, I_NaCa, depolarization-activated K⁺ currents, and ATP levels toward normal. MB improved mitochondrial membrane potential (?ψ_m) and oxygen consumption rate in myocytes in which Complex I was blocked by rotenone. We conclude that MB ameliorated H₂S-induced cardiomyocyte toxicity at multiple levels: (1) reversing excitation–contraction coupling defects (Ca²⁺ homeostasis and L-type Ca²⁺ channels); (2) reducing risks of arrhythmias (E_m, APD, I_NaCa and depolarization-activated K⁺ currents); and (3) improving cellular bioenergetics (ATP, ?ψ_m).     

Clinical and metabolic features of the randomised controlled Diabetes Remission Clinical Trial (DiRECT) cohort

Aims/hypothesis

Substantial weight loss in type 2 diabetes can achieve a return to non-diabetic biochemical status, without the need for medication. The Diabetes Remission Clinical Trial (DiRECT), a cluster-randomised controlled trial, is testing a structured intervention designed to achieve and sustain this over 2 years in a primary care setting to determine practicability for routine clinical practice. This paper reports the characteristics of the baseline cohort.

Methods

People with type 2 diabetes for <6 years with a BMI of 27–45 kg/m² were recruited in 49 UK primary care practices, randomised to either best-practice diabetes care alone or with an additional evidence-based weight management programme (Counterweight-Plus). The co-primary outcomes, at 12 months, are weight loss ≥15 kg and diabetes remission (HbA_1c <48 mmol/mol [6.5%]) without glucose-lowering therapy for at least 2 months. Outcome assessors are blinded to group assignment.

Results

Of 1510 people invited, 423 (28%) accepted; of whom, 306 (72%) were eligible at screening and gave informed consent. Seven participants were later found to have been randomised in error and one withdrew consent, leaving 298 (176 men, 122 women) who will form the intention to treat (ITT) population for analysis. Mean (SD) age was 54.4 (7.6) years, duration of diabetes 3.0 (1.7) years, BMI 34.6 (4.4) kg/m² for all participants (34.2 (4.2) kg/m² in men and 35.3 (4.6) kg/m² in women) and baseline HbA_1c (on treatment) 59.3 (12.7) mmol/mol (7.6% [1.2%]). The recruitment rate in the intervention and control groups, and comparisons between the subgroups recruited in Scotland and England, showed few differences.

Conclusions/interpretation

DiRECT has recruited a cohort of people with type 2 diabetes with characteristics similar to those seen in routine practice, indicating potential widespread applicability. Over 25% of the eligible population wished to participate in the study, including a high proportion of men, in line with the prevalence distribution of type 2 diabetes.

Trial registration

www.controlled-trials.com/ISRCTN03267836; date of registration 20 December 2013

     

Preventing falls in older multifocal glasses wearers by providing single-lens distance glasses: the protocol for the VISIBLE randomised controlled trial

Background

Recent research has shown that wearing multifocal glasses increases the risk of trips and falls in older people. The aim of this study is to determine whether the provision of single-lens distance glasses to older multifocal glasses wearers, with recommendations for wearing them for walking and outdoor activities, can prevent falls. We will also measure the effect of the intervention on health status, lifestyle activities and fear of falling, as well as the extent of adherence to the program.

Methods/Design

Approximately 580 older people who are regular wearers of multifocal glasses people will be recruited. Participants will be randomly allocated to either an intervention group (provision of single lens glasses, with counselling and advice about appropriate use) or a control group (usual care). The primary outcome measure will be falls (measured with 13 monthly calendars). Secondary measures will be quality of life, falls efficacy, physical activity levels and adverse events.

Discussions

The study will determine the impact of providing single-lens glasses, with advice about appropriate use, on preventing falls in older regular wearers of multifocal glasses. This pragmatic intervention, if found to be effective, will guide practitioners with regard to recommending appropriate glasses for minimising the risk of falls in older people.

Trial Registration

The protocol for this study was registered with the Clinical Trials.gov Protocol Registration System on June 7^th 2006 (#350855).     

Clinical trials update from the European Society of Cardiology Meeting 2009: AAA,RELY, PROTECT,ACTIVE‐I,European CRT survey,German pre‐SCD II registry,and MADIT‐CRT

This article provides information and a commentary on trials relevant to the pathophysiology, prevention, and treatment of heart failure presented at the annual meeting of the European Society of Cardiology held in Barcelona in 2009. The AAA study does not support the routine use of aspirin for the prevention of vascular events in patients with asymptomatic atherosclerosis. RELY suggests that dabigatran may be more effective than warfarin for the prevention of stroke in patients with atrial fibrillation. Rolofylline was not superior to placebo in improving outcomes in patients with acute heart failure enrolled in the PROTECT study, but dyspnoea was improved. Data from ACTIVE‐I suggest that irbesartan does not provide additional therapeutic benefit in patients with atrial fibrillation who are well controlled on current therapy. The European cardiac resynchronization therapy (CRT) survey provides interesting epidemiological data on current CRT device usage. The German pre‐SCD II registry identified a low prevalence of patients with a reduced ejection fraction following myocardial infarction. Implantation of CRT‐D rather than an implantable cardioverter defibrillator in patients with mild heart failure and QRS ≥130 ms reduced the risk of hospitalization for heart failure in MADIT‐CRT; mortality was similarly low with each device.     

Role of nitric oxide in relaxation of the longitudinal layer of rectal smooth muscle

PURPOSE: This study was designed to investigate the role of nitric oxide in neurogenic relaxation of the longitudinal layer of human rectal smooth muscle. METHODS: Tissue was obtained from the mid rectum of patients undergoing anterior resection for carcinoma. Adjacent strips of longitudinal muscle were dissected and mounted in organ baths for isometric tension recording. In preliminary experiments to determine the response of strips to cholinergic, adrenergic, and potential excitatory agonists, strips were superfused with standard Krebs solution (37±0.5°C; pH, 7.4±0.05). Investigation of inhibitory, nonadrenergic noncholinergic responses required the addition of 3×10⁻⁶ M histamine to induce reproducible and stable tension for five-minute “test” periods, during which electrical field stimulation (EFS) and additional drugs were applied. In these experiments, strips were superfused with Krebs solution that contained atropine sulfate (3×10⁻⁶ M) and guanethidine (3×10⁻⁶ M). RESULTS: The response to cholinergic and adrenergic agonists was typical of nonsphincter specialized gastrointestinal smooth muscle. EFS elicited frequency-dependent, neurogenic (tetrodotoxin-sensitive) relaxations of precontracted strips, which were reduced in dose-dependent fashion by addition ofNω-nitro-l-arginine and restored by addition of 3×10 ⁻⁴ M l-arginine but not by d-arginine. Addition of exogenous nitric oxide (sodium nitroprusside) mimicked the relaxant response induced by EFS. CONCLUSION: Smooth muscle from the longitudinal layer of human rectum receives an intrinsic inhibitory innervation mediated by nitric oxide. Supported and financed by the Medical Research Council, United Kingdom. John Stebbing is in receipt of a Medical Research Council Clinical Training Fellowship. Read at the meeting of The American Society of Colon and Rectal Surgeons, Seattle, Washington, June 9 to 14, 1996.