Clinical effectiveness of pit and fissure sealants in primary and permanent teeth of children and adolescents: an umbrella review

PURPOSE

This umbrella review aimed to critically appraise the evidence published in systematic reviews (SRs) on the clinical effectiveness of sealants compared with each other/the non-use in primary/permanent teeth of children and adolescents with at least 12-month follow-up.

METHODS

A systematic literature search on 4 electronic databases was conducted up to January 18th, 2023. Following handsearching, two review authors independently screened retrieved articles, extracted data, and assessed the risk of bias (RoB) using the risk of bias in systematic reviews (ROBIS) tool. Based on a citation matrix, the overlap was interpreted by the corrected covered area (CCA).

RESULTS

Of 239 retrieved records, 7 SRs met the eligibility criteria with a moderate overlap among them (CCA = 7.4%). For primary molars, in 1120 1.5- to 8-year-old children, data on the clinical effectiveness of sealants were inconclusive. For permanent molars, 3 SRs found a significant caries risk reduction for sealants versus non-use (≤ 36-month follow-up). There was insufficient evidence to proof superiority of sealants over fluoride varnish for caries prevention (3 SRs), and to rank sealant materials according to the best clinical effectiveness in permanent molars. One study was rated at low and 6 at high RoB, which did not allow for a valid quantitative synthesis.

CONCLUSION

Considering the limitations of this umbrella review, sealants are more effective for caries prevention in children's permanent molars compared to no treatment. Future well-implemented RCTs are needed to draw reliable conclusions on the clinical effectiveness of sealants in primary and permanent teeth of children and adolescents.

Towards Clinical Translation of Microbeam Radiation Therapy (MRT) with a Compact Source

PURPOSE/OBJECTIVE(S)

MRT is an innovative concept of spatially fractionated radiation therapy that has demonstrated substantially improved normal tissue tolerance while achieving local tumor control in a wealth of preclinical studies. In MRT a collimator shapes a few micrometers wide planar x-ray beams with a spacing of a few 100 µm. MRT has the potential to improve cancer treatment substantially. However, until now, only a few large 3rd generation synchrotrons provide beam parameters that would allow patient treatments and therefore, MRT has not yet become clinically available. For a clinical translation, compact x-ray sources are required, that produce high dose rate orthovoltage x-rays from a micrometer sized emitter.

MATERIALS/METHODS

We developed and built a first prototype of a line focus x-ray tube (LFxT) dedicated to preclinical MRT research. By exploiting the heat capacity limit, the LFxT can deliver dose rates above 100 Gy/s from a just 50 µm-wide focal spot without destroying the rapidly (>200 Hz) rotating x-ray target. A bespoke collimator splits the homogeneous x-ray field into 50 µm wide high-dose peaks separated by 350 µm wide low-dose troughs (valleys). While the prototype in our lab is restricted to a power of 90 kW and 10 Gy/s at 300 kVp, we have started the development of the first clinically usable LFxT-2 at 1.5 MW power and >100 Gy/s at 600 kVp beam quality. We investigated the clinical applicability of the LFxT-2 by performing retrospective treatment planning studies. In particular, we were examining, whether 600 kVp photons would suffice to meet clinical dose constraints in MRT treatments treatment scenarios for first clinical use of MRT. We coupled the open source platform 3D Slicer with an in-house developed dose calculation algorithm for MRT treatment planning. For comparability of spatially fractionated MRT doses with conventional broad beam treatments, the MRT dose was converted to equivalent uniform dose (EUD) and equivalent doses in 2-Gy-fractions (EQD2). The 3D Slicer RT toolkit enabled the dosimetric analysis based on dose volume histograms (DVHs).

RESULTS

We installed a preclinical prototype of the LFxT that is currently put into operation and commissioned. Simulations show the feasibility of the next generation LFxT-2 with more than 100 Gy/s peak dose rate. Planned MRT dose distributions with the LFxT-2 meet established radiotherapy dose constraints in many of the investigated clinical cases. However, treatment planning procedures are not yet optimal and require improvement.

CONCLUSION

In a next step, we will build the LFxT-2 and aim for first clinical MRT trials at this source. In order to further improve calculated MRT dose distributions, we will implement inverse treatment planning techniques.

OCT2013, an ischaemia-activated antiarrhythmic prodrug, devoid of the systemic side effects of lidocaine

BACKGROUND AND PURPOSE

Sudden cardiac death (SCD) caused by acute myocardial ischaemia and ventricular fibrillation (VF) is an unmet therapeutic need. Lidocaine suppresses ischaemia-induced VF, but its utility is limited by side effects and a narrow therapeutic index. Here, we characterise OCT2013, a putative ischaemia-activated prodrug of lidocaine.

EXPERIMENTAL APPROACH

The rat Langendorff-perfused isolated heart, anaesthetised rat and rat ventricular myocyte preparations were utilised in a series of blinded and randomised studies to investigate the antiarrhythmic effectiveness, adverse effects and mechanism of action of OCT2013, compared with lidocaine.

KEY RESULTS

In isolated hearts, OCT2013 and lidocaine prevented ischaemia-induced VF equi-effectively, but OCT2013 did not share lidocaine's adverse effects (PR widening, bradycardia and negative inotropy). In anaesthetised rats, i.v. OCT2013 and lidocaine suppressed VF and increased survival equi-effectively; OCT2013 had no effect on cardiac output even at 64 mg·kg^-1 i.v., whereas lidocaine reduced it even at 1 mg·kg^-1 . In adult rat ventricular myocytes, OCT2013 had no effect on Ca²⁺ handling, whereas lidocaine impaired it. In paced isolated hearts, lidocaine caused rate-dependent conduction slowing and block, whereas OCT2013 was inactive. However, during regional ischaemia, OCT2013 and lidocaine equi-effectively hastened conduction block. Chromatography and MS analysis revealed that OCT2013, detectable in normoxic OCT2013-perfused hearts, became undetectable during global ischaemia, with lidocaine becoming detectable.

CONCLUSIONS AND IMPLICATIONS

OCT2013 is inactive but is bio-reduced locally in ischaemic myocardium to lidocaine, acting as an ischaemia-activated and ischaemia-selective antiarrhythmic prodrug with a large therapeutic index, mimicking lidocaine's benefit without adversity.

High resolution optical mapping of cardiac electrophysiology in pre-clinical models

Optical mapping of animal models is a widely used technique in pre-clinical cardiac research. It has several advantages over other methods, including higher spatial resolution, contactless recording and direct visualisation of action potentials and calcium transients. Optical mapping enables simultaneous study of action potential and calcium transient morphology, conduction dynamics, regional heterogeneity, restitution and arrhythmogenesis. In this dataset, we have optically mapped Langendorff perfused isolated whole hearts (mouse and guinea pig) and superfused isolated atria (mouse). Raw datasets (consisting of over 400 files) can be combined with open-source software for processing and analysis. We have generated a comprehensive post-processed dataset characterising the baseline cardiac electrophysiology in these widely used pre-clinical models. This dataset also provides reference information detailing the effect of heart rate, clinically used anti-arrhythmic drugs, ischaemia-reperfusion and sympathetic nervous stimulation on cardiac electrophysiology. The effects of these interventions can be studied in a global or regional manner, enabling new insights into the prevention and initiation of arrhythmia.

Management of proximal metaphyseal curvilinear tibial fractures in 25 skeletally immature dogs (2009 to 2020)

OBJECTIVES

To describe the occurrence, management and outcome of proximal metaphyseal curvilinear tibial fractures in skeletally immature dogs.

MATERIALS AND METHODS

A multi-centre retrospective review was conducted, searching for skeletally immature dogs presenting with proximal metaphyseal curvilinear tibial fractures between January 2009 and September 2020. Signalment, fracture description and case management data were retrieved. Outcome was assessed by retrospectively evaluating follow-up radiographs, hospital records and an owner questionnaire.

RESULTS

Twenty-five dogs met the inclusion criteria. All but one fracture was a result of minimal trauma. Twenty fractures were managed with internal fixation, two with external fixation and three conservatively. All 25 fractures healed. Eight major complications occurred in seven of 25 (28%) dogs. Twelve minor complications occurred in 10 of 25 (40%) dogs. Owner questionnaire data were available for 12 of 25 dogs; 11 of 12 were reported as having full function and one of 12 as having acceptable function at the time of questioning (median 34.5 months following presentation). At final follow-up, either by clinical examination or owner questionnaire, full function was achieved in 22 of 25 patients and acceptable function in three of 25.

CLINICAL SIGNIFICANCE

This study reported a series of proximal metaphyseal tibial fractures in skeletally immature dogs. The most common fixation method was internal fixation, which frequently resulted in full limb function at final follow-up. Owners reported outcome as fully functional in all dogs that underwent surgery at first presentation and had owner follow-up available, though positive outcomes may have been affected by participation bias.

Marker-less online MR-guided stereotactic body radiotherapy of liver metastases at a 1.5 T MR-Linac - Feasibility, workflow data and patient acceptance

INTRODUCTION

Stereotactic body radiotherapy (SBRT) is an established ablative treatment for liver tumors with excellent local control rates. Magnetic resonance imaging guided radiotherapy (MRgRT) provides superior soft tissue contrast and may therefore facilitate a marker-less liver SBRT workflow. The goal of the present study was to investigate feasibility, workflow parameters, toxicity and patient acceptance of MRgSBRT on a 1.5 T MR-Linac.

METHODS

Ten consecutive patients with liver metastases treated on a 1.5 T MR-Linac were included in this prospective trial. Tumor delineation was performed on four-dimensional computed tomography scans and both exhale triggered and free-breathing T2 MRI scans from the MR-Linac. An internal target volume based approach was applied. Organ at risk constraints were based on the UKSABR guidelines (Version 6.1). Patient acceptance regarding device specific aspects was assessed and toxicity was scored according to the common toxicity criteria of adverse events, version 5.

RESULTS

Nine of ten tumors were clearly visible on the 1.5 T MR-Linac. No patient had fiducial markers placed for treatment. All patients were treated with three or five fractions. Median dose to 98% of the gross tumor volume was 38.5 Gy. The median time from "patient identity check" until "beam-off" was 31 min. Median beam on time was 9.6 min. Online MRgRT was well accepted in general and no treatment had to be interrupted on patient request. No event of symptomatic radiation induced liver disease was observed after a median follow-up of ten month (range 3-17 months).

CONCLUSION

Our early experience suggests that online 1.5 T MRgSBRT of liver metastases represents a promising new non-invasive marker-free treatment modality based on high image quality, clinically reasonable in-room times and high patient acceptance. Further studies are necessary to assess clinical outcome, to validate advanced motion management and to explore the benefit of online response adaptive liver SBRT.

Novel effects of Foxo3a on immune system and cardiac remodeling after myocardial infarction

Background

Fibroblast/myofibroblast transdifferentiation following acute cardiac injury (MI) is a major mechanism of scar formation and adverse remodeling regulated by TGFβ/SMAD3 signaling. Myofibroblasts represent phenotypically modulated cells characterized by α-smooth muscle actin (α-SMA) and constitute the main source of extracellular matrix proteins such as collagen type I in the healing infarct wound. Moreover, the recruitment of a specific monocyte/macrophages subset (Ly6Chigh and Ly6Clow) control the healing process in the infarcted wound. The forkhead transcription factor FOXO3a has recently been shown to inhibit cardiac hypertrophy by different stressors and is involved in the immune response following injury.

Purpose

We hypothesized that FOXO3a, a key regulator of cell differentiation, cell cycle and size as well as the stress response, might inhibit matricellular remodeling following myocardial infarction by regulating transdifferentiation of fibroblasts into myofibroblasts. Moreover, we hypothesized that Foxo3a−/− mice favor the recruitment of monocytes of the type Ly6Clow leading to an anti-inflammatory profile and thus the remodeling after injury.

Methods

Acute myocardial infarction was induced in FOXO3−/− and WT mice (FVB background) by permanent LAD ligation. The myocardial infarction size was determined via ECHO. Myofibroblast trans-differentiation and fibrosis markers were analyzed by QT-PCR and protein analysis. The differentiation of macrophages studied via FACS. IP/IF and Western blotting were used to test for a direct interaction between FOXO3a and SMAD3 in vitro.

Results

FOXO3a−/− mice showed significantly higher survival rates compared to WT littermates. Myocardial inflammation (Mac-1, LFA, CD3, CD45), injury markers such as Troponin T were similar in both groups on day 4 post-MI. Myocardial expression of alpha smooth muscle actin (ASMA) and Collagen1A1 (Col1A1), as well as numbers of cardiac CD11b+/F4–80+/Ly6clow macrophages was significantly enhanced in FOXO3a−/− mice 15 days post infarction. Moreover, Foxo3a−/− mice showed larger fibrotic areas following MI. Mechanistically, immunoprecipitation showed direct interaction of FOXO3a with SMAD3a that was enhanced following activation of the transcription factor leading to diminished SMAD3 downstream gene expression.

Conclusion

Our results indicate that FOXO3a acts as a direct inhibitor of TGF-β regulated myofibroblast differentiation and matrix remodeling via FOXO3a-SMAD3 interaction following MI. Moreover, a Foxo3a deficiency might lead to the recruitment of monocytes type Ly6Clow leading to an anti-inflammatory profile in the infarct wound. Therefore, FOXO3a collectively regulates cardiac hypertrophy and fibrosis/scar formation following MI. Thus, targeting the FOXO3a-SMAD3 signaling axis might be of future therapeutic interest.

Funding Acknowledgement

Type of funding source: Foundation. Main funding source(s): German Resaerch Foundation

[Autopneumonectomie. A Forgotten Disease]

HISTORY

 An 80-year old female was referred to our hospital with left internal carotid artery stenosis and a childhood history of hemoptysis.

INVESTIGATIONS AND DIAGNOSIS

 The ECG showed 2nd degree Mobitz atrio-ventricular block. The chest x-ray and computerized tomography identified a shift of the mediastinum and the heart to the left. The left lung was completely destroyed whilst the right lung was enlarged and crossed the midline. Pulmonary function tests revealed a moderate restrictive ventilation disorder. The diagnosis of autopneumonectomy was based on patient history together with radiological findings.

TREATMENT AND COURSE

 A pacemaker was implanted with two stimulation electrodes via a left cephalic venous cutdown. A carotid endarterectomy was also performed without any complication.

CONCLUSION

 After autopneumonectomy, postpneumonectomy like syndrome may occur in very rare cases, whereupon operative treatment is mandatory. Any respiratory infections should be treated with antibiotics. Pacemaker electrode placement via the subclavian vein is contraindicated due to the risk of a catastrophic pneumothorax.

The Amplitude-Normalized Area of a Bipolar Electrogram as a Measure of Local Conduction Delay in the Heart

BACKGROUND

Re-entrant ventricular tachycardia may be non-inducible or haemodynamically compromising, requiring assessment of the electrophysiological properties of the myocardium during sinus rhythm (i.e., substrate mapping). Areas of heart tissue with slow conduction can act as a critical isthmus for re-entrant electrical excitation and are a potential target for ablation therapy.

AIM

To develop and validate a novel metric of local conduction delay in the heart, the amplitude-normalized electrogram area (norm_EA).

METHODS

A computational model of a propagating mouse action potential was used to establish the impact of altering sodium channel conductance, intracellular conductivity, fibrosis density, and electrode size/orientation on bipolar electrogram morphology. Findings were then validated in experimental studies in mouse and guinea pig hearts instrumented for the recording of bipolar electrograms from a multipolar linear mapping catheter. norm_EA was calculated by integrating the absolute area of a bipolar electrogram divided by the electrogram amplitude. Electrogram metrics were correlated with the local conduction delay during sodium channel block, gap junction inhibition, and acute ischemia.

RESULTS

In computational simulations, reducing sodium channel conductance and intracellular conductivity resulted in a decrease in signal amplitude and increase in norm_EA (reflecting a broadening of electrogram morphology). For larger electrodes (3 mm diameter/7.1 mm2 area), the change in norm_EA was essentially linear with the change in local conduction delay. Experimental studies supported this finding, showing that the magnitude of change in norm_EA induced by flecainide (1-4 μM), carbenoxolone (10-50 μM), and low-flow ischemia (25% of initial flow rate) was linearly correlated with the local conduction delay in each condition (r 2 = 0.92). Qualitatively similar effects were observed in guinea pig hearts perfused with flecainide. Increasing fibrosis density in the computational model also resulted in a decrease in signal amplitude and increase in norm_EA. However, this remains to be validated using experimental/clinical data of chronic infarct.

CONCLUSION

norm_EA is a quantitative measure of local conduction delay between the electrode pair that generates a bipolar electrogram, which may have utility in electrophysiological substrate mapping of non-inducible or haemodynamically compromising tachyarrhythmia.

Examination of the Effects of Conduction Slowing on the Upstroke of Optically Recorded Action Potentials

Introduction

The upstroke of optical action potentials (APs) recorded from intact hearts are generally recognized to be slower than those recorded with microelectrodes. This is thought to reflect spatial signal averaging within the volume of tissue that makes up the optical signal. However, to date, there has been no direct experimental study on the relationship between conduction velocity (CV) and optical AP upstroke morphology in the intact heart. Notably, it is known that sodium channel block and gap junction inhibition, which both slow CV, exert differential effects on the upstroke velocity of microelectrode-recorded APs. Whether such differences are evident in optical APs is not known. The present study sought to determine the relationship between tissue CV and optical AP upstroke velocity in intact mouse hearts.

Materials and Methods

Isolated, perfused mouse hearts were stained with the potentiometric dye Rh-237. Fluorescent signals were recorded from across the anterior surface of the left and right ventricles during constant pacing. Maximum rate of change in fluorescence (dF/dt_max) and tissue CV were assessed in control conditions, during an acute period of low-flow ischemia, and following perfusion of flecainide (1–3 μmol/L), a sodium channel blocker, or carbenoxolone (10–50 μmol/L), a gap junction inhibitor.

Results

During epicardial pacing, an anisotropic pattern was observed in both activation and dF/dt_max maps, with more rapid optical AP upstroke velocities orientated along the fastest conduction paths (and vice versa). Low-flow ischemia resulted in a time-dependent slowing of ventricular CV, which was accompanied by a concomitant reduction in optical AP upstroke velocity. All values returned to baseline on tissue reperfusion. Both flecainide and carbenoxolone were associated with a concentration-dependent reduction in CV and decrease in optical AP upstroke velocity, despite distinct mechanisms of action. Similar responses to carbenoxolone were observed for low- (156 μm pixel with) and high- (20 μm pixel width) magnification recordings. Comparison of data from all interventions revealed a linear relationship between CV and upstroke dF/dt.

Conclusion

In intact mouse hearts, slowing of optical AP upstroke velocity is directly proportional to the change in CV associated with low-flow ischemia, sodium channel block, and gap junction inhibition.

Supportive care needs of patients following treatment for colorectal cancer: risk factors for unmet needs and the association between unmet needs and health-related quality of life-results from the ColoREctal Wellbeing (CREW) study

Purpose

To investigate unmet needs of patients with colorectal cancer (CRC) at the end of treatment and whether unmet needs improve over time. Identify predictors of need following treatment and whether unmet need is associated with worse health-related quality of life (HRQoL).

Methods

As part of the UK ColoREctal Wellbeing (CREW) cohort study, patients treated for CRC completed the Supportive Care Needs Survey Short Form-34 (SCNS SF-34) 15 and 24 months following surgery, along with questionnaires measuring HRQoL, wellbeing, life events, social support, and confidence to manage their cancer before surgery, 3, 9, 15, and 24 months post-surgery.

Results

The SCNS SF-34 was completed by 526 patients at 15 months and 510 patients at 24 months. About one-quarter of patients had at least one moderate or severe unmet need at both time points. Psychological and physical unmet needs were the most common and did not improve over time. Over 60% of patients who reported 5 or more moderate or severe unmet needs at 15 months experienced the same level of unmet need at 24 months. HRQoL at the beginning of treatment predicted unmet needs at the end of treatment. Unmet needs, specifically physical, psychological, and health system and information needs, were associated with poorer health and HRQoL at the end of treatment.

Conclusions

Unmet needs persist over time and are associated with HRQoL. Evaluation of HRQoL at the start of treatment would help inform the identification of vulnerable patients. Assessment and care planning in response to unmet needs should be integrated into person-centred care.

Implications for Cancer Survivors

Early identification of CRC patients at risk of unmet needs will help infrom personalised survivorship care plans. The implementation of personalised and tailored services are likely to confer HRQoL gains.

Electronic supplementary material

The online version of this article (10.1007/s11764-019-00805-6) contains supplementary material, which is available to authorized users.

High-Throughput Analysis of Optical Mapping Data Using ElectroMap

Optical mapping is an established technique for high spatio-temporal resolution study of cardiac electrophysiology in multi-cellular preparations. Here we present, in a step-by-step guide, the use of ElectroMap for analysis, quantification, and mapping of high-resolution voltage and calcium datasets acquired by optical mapping. ElectroMap analysis options cover a wide variety of key electrophysiological parameters, and the graphical user interface allows straightforward modification of pre-processing and parameter definitions, making ElectroMap applicable to a wide range of experimental models. We show how built-in pacing frequency detection and signal segmentation allows high-throughput analysis of entire experimental recordings, acute responses, and single beat-to-beat variability. Additionally, ElectroMap incorporates automated multi-beat averaging to improve signal quality of noisy datasets, and here we demonstrate how this feature can help elucidate electrophysiological changes that might otherwise go undetected when using single beat analysis. Custom modules are included within the software for detailed investigation of conduction, single file analysis, and alternans, as demonstrated here. This software platform can be used to enable and accelerate the processing, analysis, and mapping of complex cardiac electrophysiology.

Probabilistic graphical model identifies clusters of EEG patterns in recordings from neonates

OBJECTIVES

In this paper we introduce a novel method for the evaluation of neonatal brain function via multivariate EEG (electroencephalography) signal processing and embedding into a probabilistic graph, the so called Chow-Liu tree.

METHODS

Using 28 EEG recordings of preterm and term neonate infants the complex features of the EEG signals were constructed in the form of a Chow-Liu tree. The trees were embedded into a 3 dimensional Euclidean space. Clustering of specific EEG patterns was done by complete linkage algorithm.

RESULTS

Our analytic tool was able to build clusters of patients with pathological EEG findings. In particular, we were able to make a visual proof on a 3d multidimensional scaling coordinate system with a good performance. The distances (graph edit distance) between Chow-Liu trees of different infants were proportional to the clinical findings of corresponding infants.

CONCLUSION

Our method may provide a basis for the future development of a diagnostic/prognostic non-invasive brain monitoring tool which will be able to differentiate between a variety of complex clinical findings.

SIGNIFICANCE

This model addresses relevant issues in neonatology and neuropediatrics in terms of identification of possible clinical factors which interfere with normal brain development and will allow fast unbiased recognition of infants with specific pathological EEG findings.

Stimulation with Porphyromonas gingivalis enhances malignancy and initiates anoikis resistance in immortalized oral keratinocytes

The aim of this study was to get new insights into molecular processes involved in tumor propagation of immortalized oral keratinocytes induced by the keystone pathogen Porphyromonas gingivalis. Cell culture experiments with immortalized OKF6 cells were performed to analyze cellular effects caused by bacterial stimulation focusing on altered gene expression, signaling pathways, proliferation rate, cell viability, migration and invasion behavior, and on the development of antiapoptotic pathways. Gene and protein expression were analyzed using real-time polymerase chain reaction, enzyme-linked immunosorbent assay, western blot, and protein arrays. Trypan blue staining was used to analyze proliferation and viability, transwell assays for cellular migration, Matrigel assays for invasion, and anoikis-assays for evaluating anoikis resistance. Stimulation of OKF6 cells with Porphyromonas gingivalis led to an alteration in the molecular repertoire of proteins which are involved in cell proliferation, epithelial-mesenchymal transition, stem cell formation, migration, invasion, and anoikis resistance. Higher proliferation rates were detected in conjunction with an activation of PI3K/Akt signaling and the mTOR-pathway. Additionally, inhibition of glycogen-synthase-kinase3-β led to stabilization of β-catenin and Snail, which resulted in a switch from predominant E-cadherin to N-cadherin expression and increased expression of the stem cell markers Oct3/4, Sox2, and Nanog. Enhanced biosynthesis and enzyme activity of matrix metalloproteinase-9 was accompanied by elevated invasion behavior. Finally, anoikis resistance was detected in stimulated keratinocytes by decreased apoptosis of nonadherent cells and elevated expression of epidermal growth factor receptor and c-Met. Hence, Porphyromonas gingivalis is able to induce a more aggressive tumor-like phenotype in immortalized oral keratinocytes, thus contributing to enhanced tumor features.

Cardiac Optogenetics and Optical Mapping - Overcoming Spectral Congestion in All-Optical Cardiac Electrophysiology

Optogenetic control of the heart is an emergent technology that offers unparalleled spatio-temporal control of cardiac dynamics via light-sensitive ion pumps and channels (opsins). This fast-evolving technique holds broad scope in both clinical and basic research setting. Combination of optogenetics with optical mapping of voltage or calcium fluorescent probes facilitates 'all-optical' electrophysiology, allowing precise optogenetic actuation of cardiac tissue with high spatio-temporal resolution imaging of action potential and calcium transient morphology and conduction patterns. In this review, we provide a synopsis of optogenetics and discuss in detail its use and compatibility with optical interrogation of cardiac electrophysiology. We briefly discuss the benefits of all-optical cardiac control and electrophysiological interrogation compared to traditional techniques, and describe mechanisms, unique features and limitations of optically induced cardiac control. In particular, we focus on state-of-the-art setup design, challenges in light delivery and filtering, and compatibility of opsins with fluorescent reporters used in optical mapping. The interaction of cardiac tissue with light, and physical and computational approaches to overcome the 'spectral congestion' that arises from the combination of optogenetics and optical mapping are discussed. Finally, we summarize recent preclinical work applications of combined cardiac optogenetics and optical mapping approach.

ElectroMap: High-throughput open-source software for analysis and mapping of cardiac electrophysiology

The ability to record and analyse electrical behaviour across the heart using optical and electrode mapping has revolutionised cardiac research. However, wider uptake of these technologies is constrained by the lack of multi-functional and robustly characterised analysis and mapping software. We present ElectroMap, an adaptable, high-throughput, open-source software for processing, analysis and mapping of complex electrophysiology datasets from diverse experimental models and acquisition modalities. Key innovation is development of standalone module for quantification of conduction velocity, employing multiple methodologies, currently not widely available to researchers. ElectroMap has also been designed to support multiple methodologies for accurate calculation of activation, repolarisation, arrhythmia detection, calcium handling and beat-to-beat heterogeneity. ElectroMap implements automated signal segmentation, ensemble averaging and integrates optogenetic approaches. Here we employ ElectroMap for analysis, mapping and detection of pro-arrhythmic phenomena in silico, in cellulo, animal model and in vivo patient datasets. We anticipate that ElectroMap will accelerate innovative cardiac research and enhance the uptake, application and interpretation of mapping technologies leading to novel approaches for arrhythmia prevention.

Restitution slope is principally determined by steady-state action potential duration

Aims

The steepness of the action potential duration (APD) restitution curve and local tissue refractoriness are both thought to play important roles in arrhythmogenesis. Despite this, there has been little recognition of the apparent association between steady-state APD and the slope of the restitution curve. The objective of this study was to test the hypothesis that restitution slope is determined by APD and to examine the relationship between restitution slope, refractoriness and susceptibility to VF.

Methods and results

Experiments were conducted in isolated hearts and ventricular myocytes from adult guinea pigs and rabbits. Restitution curves were measured under control conditions and following intervention to prolong (clofilium, veratridine, bretylium, low [Ca]e, chronic transverse aortic constriction) or shorten (catecholamines, rapid pacing) ventricular APD. Despite markedly differing mechanisms of action, all interventions that prolonged the action potential led to a steepening of the restitution curve (and vice versa). Normalizing the restitution curve as a % of steady-state APD abolished the difference in restitution curves with all interventions. Effects on restitution were preserved when APD was modulated by current injection in myocytes pre-treated with the calcium chelator BAPTA-AM – to abolish the intracellular calcium transient. The non-linear relation between APD and the rate of repolarization of the action potential is shown to underpin the common influence of APD on the slope of the restitution curve. Susceptibility to VF was found to parallel changes in APD/refractoriness, rather than restitution slope.

Conclusion(s)

Steady-state APD is the principal determinant of the slope of the ventricular electrical restitution curve. In the absence of post-repolarization refractoriness, factors that prolong the action potential would be expected to steepen the restitution curve. However, concomitant changes in tissue refractoriness act to reduce susceptibility to sustained VF. Dependence on steady-state APD may contribute to the failure of restitution slope to predict sudden cardiac death.

Intermuscular implantation technique for subcutaneous cardioverter-defibrillators

BACKGROUND

The conventional technique for subcutaneous implantable cardioverter-defibrillator (S-ICD) implantation has been associated with pocket complications. The aim of this study was to evaluate the efficacy and safety of an alternative intermuscular technique for S‑ICD implantation.

METHODS

S-ICDs were implanted in ten consecutive patients (ten males, mean age: 46.8 ± 14.7 years). The pocket for the pulse generator was made above the serratus anterior muscular fascia and beneath the latissimus dorsi muscle by detaching the fibrous tissue between the muscles. Electrode implantation was performed using the three- (n = 4) or the two-incision technique (n = 6).

RESULTS

All S‑ICDs were successfully implanted in the absence of any procedure-related complications with a successful 65-J standard polarity defibrillation threshold testing, apart from one patient with Brugada syndrome who needed device repositioning more dorsally. During a mean follow-up of 16.5 ± 7.3 months, no major complications requiring surgical repair were encountered, while patients demonstrated high levels of comfort and satisfaction with the cosmetic result. One patient experienced an inappropriate shock due to noise detection, which was resolved after reprogramming to a different sensing vector.

CONCLUSION

The intermuscular technique is a safe and efficacious approach for S‑ICD implantation. This technique could lead to fewer pocket-related complications and better cosmetic results.

System Design of a Computer Based Library Circulation System for the Radiology File Room

The operation and configuration of a reliable and inexpensive computer based system for locating X-ray film jackets are proposed. Card-dialer Touch-Tone telephones are used to accurately inform the computer of loans, to reserve film jackets, and to inquire about their locations. Computerassisted identification and recall of overdue and reserved film jackets increases their availability and the efficiency of file room personnel.

Sympathetic Nervous Regulation of Calcium and Action Potential Alternans in the Intact Heart

Rationale: Arrhythmogenic cardiac alternans are thought to be an important determinant for the initiation of ventricular fibrillation. There is limited information on the effects of sympathetic nerve stimulation (SNS) on alternans in the intact heart and the conclusions of existing studies, focused on investigating electrical alternans, are conflicted. Meanwhile, several lines of evidence implicate instabilities in Ca handling, not electrical restitution, as the primary mechanism underpinning alternans. Despite this, there have been no studies on Ca alternans and SNS in the intact heart. The present study sought to address this, by application of voltage and Ca optical mapping for the simultaneous study of APD and Ca alternans in the intact guinea pig heart during direct SNS.

Objective: To determine the effects of SNS on APD and Ca alternans in the intact guinea pig heart and to examine the mechanism(s) by which the effects of SNS are mediated.

Methods and Results: Studies utilized simultaneous voltage and Ca optical mapping in isolated guinea pig hearts with intact innervation. Alternans were induced using a rapid dynamic pacing protocol. SNS was associated with rate-independent shortening of action potential duration (APD) and the suppression of APD and Ca alternans, as indicated by a shift in the alternans threshold to faster pacing rates. Qualitatively similar results were observed with exogenous noradrenaline perfusion. In contrast with previous reports, both SNS and noradrenaline acted to flatten the slope of the electrical restitution curve. Pharmacological block of the slow delayed rectifying potassium current (I_Ks), sufficient to abolish I_Ks-mediated APD-adaptation, partially reversed the effects of SNS on pacing-induced alternans. Treatment with cyclopiazonic acid, an inhibitor of the sarco(endo)plasmic reticulum ATPase, had opposite effects to that of SNS, acting to increase susceptibility to alternans, and suggesting that accelerated Ca reuptake into the sarcoplasmic reticulum is a major mechanism by which SNS suppresses alternans in the guinea pig heart.

Conclusions: SNS suppresses calcium and action potential alternans in the intact guinea pig heart by an action mediated through accelerated Ca handling and via increased I_Ks.

Das equine leukämische Lymphom – eine seltene Unterart des equinen Lymphoms

Das equine leukämische Lymphom ist eine selten vorkommende Erkrankung des hämatopoetischen Gewebes. Es entsteht durch neoplastische Entartung von B- und T-Lymphozyten im Lymphgewebe und deren Auftreten in der Blutbahn. Die klinischen Symptome sind häufig unspezifisch und umfassen chronischen Gewichtsverlust, Ödeme an Unterbrust und Unterbauch sowie regionale Lymphadenopathien. Häufig werden die Pferde erst spät im Krankheitsverlauf vorgestellt und die Behandlung führt selten zum Erfolg. Die Übersichtsarbeit beschreibt klinische Symptome des equinen leukämischen Lymphoms, Befunde der labordiagnostischen sowie anderer weiterführender Untersuchungen und stellt die bisher aus der Literatur bekannten Therapieansätze dar.