Global constructive work is associated with ventricular arrhythmias after cardiac resynchronization therapy

AIMS

Non-invasive left ventricular (LV) pressure-strain loops provide a novel method for quantifying myocardial work by incorporating LV pressure in measurements of myocardial deformation. Early studies suggest that myocardial work parameters such as global constructive work (GCW) could be useful and reliable in arrhythmia prediction, particularly in patients undergoing cardiac resynchronization therapy (CRT). The aim of this study was to evaluate whether the magnitude of GCW was associated with the occurrence of ventricular arrhythmias in patients after CRT.

METHODS AND RESULTS

Patients on guideline-recommended treatment with a CRT defibrillator (CRT-D) were evaluated by 2D speckle-tracking echocardiography including measurements of GCW at least 6 months after implantation. The primary outcome was a composite of appropriate defibrillator therapy and sustained ventricular arrhythmia under the monitor zone. A total of 162 patients [mean age 66 years (±10), 122 males (75%)] were included. Sixteen (10%) patients experienced the primary outcome during a median follow-up of 18 months (interquartile range: 12-25) after the performance of index echocardiography. Patients with a below-median GCW (<1473 mmHg%) had a hazard ratio (HR) for the outcome of 8.14 [95% confidence interval (CI): 1.83-36.08], P = 0.006 compared with patients above the median in a univariate model and remained an independent predictor after multivariate adjustment for the estimated glomerular filtration rate and QRS duration [HR 4.75 (95% CI: 1.01-22.28), P < 0.05].

CONCLUSION

In patients treated with CRT-D, a GCW below median level was associated with a five-fold increase in the risk of ventricular arrhythmias.

The effect of increased plasma potassium on myocardial function; a randomized POTCAST substudy

Plasma potassium (p-K) in the high-normal range has been suggested to reduce risk of cardiovascular arrythmias and mortality through electrophysiological and mechanical effects on the myocardium. In this study, it was to investigated if increasing p-K to high-normal levels improves systolic- and diastolic myocardial function in patients with low-normal to moderately reduced left ventricular ejection fraction (LVEF). The study included 50 patients (mean age 58 years (SD 14), 81% men), with a mean p-K 3.95 mmol/l (SD 0.19), mean LVEF 48% (SD 7), and mean Global Longitudinal Strain (GLS) -14.6% (SD 3.1) patients with LVEF 35-55% from "Targeted potassium levels to decrease arrhythmia burden in high-risk patients with cardiovascular diseases trial" (POTCAST). Patients were given standard therapy and randomized (1:1) to an intervention that included guidance on potassium-rich diets, potassium supplements, and mineralocorticoid receptor antagonists targeting high-normal p-K levels (4.5-5.0 mmol/l). Echocardiography was done at baseline and after a mean follow-up of 44 days (SD 18) and the echocardiograms were analyzed for changes in GLS, mechanical dispersion, E/A, e', and E/e'. At follow-up, mean difference in changes in p-K was 0.52 mmol/l (95%CI 0.35;0.69), P<0.001 in the intervention group compared to controls. GLS was improved with a mean difference in changes of -1.0% (-2;-0.02), P<0.05 and e' and E/e' were improved with a mean difference in changes of 0.9 cm/s (0.02;1.7), P = 0.04 and ? 1.5 (-2.9;-0.14), P = 0.03, respectively. Thus, induced increase in p-K to the high-normal range improved indices of systolic and diastolic function in patients with low-normal to moderately reduced LVEF.

Treatment-induced increase in total body potassium in patients at high risk of ventricular arrhythmias; a randomized POTCAST substudy

OBJECTIVE

Hypokalemia is associated with increased risk of arrhythmias and it is recommended to monitor plasma potassium (p-K) regularly in at-risk patients with cardiovascular diseases. It is poorly understood if administration of potassium supplements and mineralocorticoid receptor antagonists (MRA) aimed at increasing p-K also increases intracellular potassium.

METHODS

Adults aged≥18 years with an implantable cardioverter defibrillator (ICD) were randomized (1:1) to a control group or to an intervention that included guidance on potassium rich diets, potassium supplements, and MRA to increase p-K to target levels of 4.5-5.0 mmol/l for six months. Total-body-potassium (TBK) was measured by a Whole-Body-Counter along with p-K at baseline, after six weeks, and after six months.

RESULTS

Fourteen patients (mean age: 59 years (standard deviation 14), 79% men) were included. Mean p-K was 3.8 mmol/l (0.2), and mean TBK was 1.50 g/kg (0.20) at baseline. After six-weeks, p-K had increased by 0.47 mmol/l (95%CI:0.14;0.81), p = 0.008 in the intervention group compared to controls, whereas no significant difference was found in TBK (44 mg/kg (-20;108), p = 0.17). After six-months, no significant difference was found in p-K as compared to baseline (0.16 mmol/l (-0.18;0.51), p = 0.36), but a significant increase in TBK of 82 mg/kg (16;148), p = 0.017 was found in the intervention group compared to controls.

CONCLUSIONS

Increased potassium intake and MRAs increased TBK gradually and a significant increase was seen after six months. The differentially regulated p-K and TBK challenges current knowledge on potassium homeostasis and the time required before the full potential of p-K increasing treatment can be anticipated.

TRIAL REGISTRATION

www.clinicaltrials.gov (NCT03833089).

Targeted potassium levels to decrease arrhythmia burden in high risk patients with cardiovascular diseases (POTCAST): Study protocol for a randomized controlled trial

BACKGROUND

Low plasma potassium (p-K) is associated with increased risk of malignant arrhythmia and observational studies indicate protective effects of p-K in the upper reference level. However, randomized clinical studies are needed to document whether actively increasing p-K to high-normal levels is possible and safe and improves cardiovascular outcomes.

OBJECTIVE

To investigate if increased p-K reduces the risk of malignant arrhythmia and all-cause death in high-risk patients with a cardiovascular disease treated with an implantable cardioverter defibrillator (ICD) for primary or secondary preventive causes. Secondly, to investigate whether high-normal p-K levels can be safely reached and maintained using already available medications and potassium-rich dietary guidance.

METHODS

This is a prospective, randomized, and open-labelled study enrolling patient at high-risk of malignant arrhythmias. According to sample size calculations, 1,000 patients will be randomized 1:1 to either an investigational regiment that aims to increase and maintain p-K at high-normal levels (4.5-5.0 mmol/L) or to usual standard of care and followed for an expected four years. The trial will run until a total of 291 events have occurred providing an α = 0.05 and 1-β = 0.80. The composite primary endpoint includes ventricular tachycardia >125 bpm lasting >30 seconds, any appropriate ICD-therapy, and all-cause mortality. At present, 739 patients have been randomized.

CONCLUSIONS

We present the rationale for the design of the POTCAST trial. The inclusion was initiated 2019 and is expected to be finished 2022. The study will show if easily available treatments to increase p-K may be a new treatment modality to protect against malignant arrythmias.

Treatment patterns for oral anticoagulants in older patients with atrial fibrillation: a retrospective, cross-sectional, nationwide study from Denmark

OBJECTIVES

Atrial fibrillation (AF) is a predominant risk factor of ischaemic stroke and treatment with oral anticoagulants (OACs) is recommended in all patients with risk factors. This study sought to examine treatment patterns of OACs in older patients with AF.

DESIGN

Retrospective, cross-sectional study.

SETTING

Danish nationwide administrative and clinical registers and databases.

PARTICIPANTS

A total of 40 027 patients, >75 years of age, after their first hospital contact due to AF between 2010 and 2018.

PRIMARY AND SECONDARY OUTCOMES MEASURES

The primary event of interest was claimed prescriptions for OACs within 180 days after first hospital contact due to AF. Proportions of patients treated with OACs were estimated and clinical factors associated with the probability of receiving OAC treatment were identified using adjusted logistic regression models.

RESULTS

A total of 40 027 patients were included with a slight majority of women (54%). The median age was 81 years (IQR 78-86). We found that an overall 32 235 patients (81%) were prescribed an OAC after their first hospital contact due to AF with a marked increase in the proportion of patients treated from 2010 to 2018. Factors related to a decreased probability of receiving treatment were bleeding risk factors such as a history of haemorrhagic stroke (OR 0.21, 95% CI 0.16 to 0.27), any bleeding (OR 0.58, 95% CI 0.53 to 0.62) as well as markers of frailty such as osteoporosis (OR 0.78, 95% CI 0.71 to 0.85).

CONCLUSION

In this large nationwide study, we found that in older patients with AF, the overall rates of OAC prescription were generally high (~80%) and increasing during the last decade. Factors associated with not receiving guideline recommended OAC treatment were generally related to bleeding risk factors or frailty.

Tomographic Study of Mesopore Formation in Ceria Nanorods

Porosity in functional oxide nanorods is a recently discovered new type of microstructure, which is not yet fully understood and still under evaluation for its impact on applications in catalysis and gas/ion storage. Here we explore the shape and distribution of pores in ceria in three dimensions using a modified algorithm of geometric tomography as a reliable tool for reconstructing defective and strained nanoobjects. The pores are confirmed as "negative-particle" or "inverse-particle" cuboctahedral shapes located exclusively beneath the flat surface of the rods separated via a sub-5 nm thin ceria wall from the outside. New findings also comprise elongated "negative-rod" defects, seen as embryonic nanotubes, and pores in cube-shaped ceria. Furthermore, we report near-sintering secondary heat treatment of nanorods and cubes, confirming persistence of pores beyond external surface rounding. We support our experiments with molecular modeling and predict that the growth history of voids is via diffusion and aggregation of atomic point defects. In addition, we use density functional theory to show that the relative stability of pore (shape) increases in the order "cuboidal" < "hexagonal-prismatic" < "octahedral". The results indicate that by engineering voids into nanorods, via a high-temperature postsynthetic heat treatment, a potential future alternative route of tuning catalytic activities might become possible.

Mobile Cloud Forensic Readiness Process Model for Cloud-Based Mobile Applications

Nowadays, mobile cloud applications have attracted millions of smartphone users due to the proliferation of cyber technologies and a wide range of applications. Mobile cloud forensic investigation methodologies need tremendous growth due to the increasing crime incidents. The forensic readiness model plays a significant role in the forensic investigation framework by ensuring the ease of investigation to the forensic investigator. The existing forensic readiness supports either the mobile device or cloud environment, which lacks to prepare the information for the investigation. This article presents a mobile cloud forensic readiness process model to identify the factors and prepare the information that effectively supports forensic investigations. The proposed model involves requirements for the mobile cloud forensics from multiple perspectives with the aim of developing the forensic-ready system. As a result, the proposed forensic readiness model enables the mobile cloud forensic to improve the accuracy of investigation as well as reduces the investigation time significantly.

Effect of Surfactants on Electrochemical Properties of Vanadium-Pentoxide Nanoparticles Synthesized via Hydrothermal Method

Vanadium pentoxide (V2O5) nanoparticles were synthesized via an anionic, cationic and non-ionic surfactant assisted hydrothermal method in which Ammonium metavanadate (NH4VO3) was used as precursor. The synthesized nanoparticles were characterized by using powder X-Ray Diffractometer, Scanning Electron Microscopy and UV-Vis spectroscopy. Crystalline nanoparticles were formed using different surfactants like Sodium Dodecyl Sulphate (SDS), Cetyltrimethylammonium Bromide (CTAB), Polyvenylpyrollidone (PVP) and Sodium Dodecyl Benzene Sulfonate (SDBS). The specific capacitance of V2O5 was calculated in 0.5 M KCl and 0.5 M Na2SO4 aqueous electrolyte by using cyclic voltammetry (CV). Electrochemical impedance, and Chronocoulommetry studies revealed a good capacitive and charge-discharge behavior of the prepared V2O5, which is very promising for the application for next-generation high-performance electro-chemical supercapacitors.

Enhanced photocatalytic efficacy of hetropolyacid pillared TiO2 nanocomposites

The removal of dye from industrial effluents is prime important, photo-catalysis is a finest method to combat dye from effluents. This study concerns about the investigation of photocatalytic activity of TiO2-HPAs (Hetropolyacids) nanocomposite namely TiO2-Phosphomolybdic nanocomposite [TiO2-HMA] and TiO2-Phosphotungstic nanocomposite [TiO2-HWA] which were prepared by Sol-gel method and the same were characterized by using XRD, SEM-EDAX. The photocatalytic activity of prepared photo-catalysts were evaluated and compared by the degradation of Methylene Blue dye in water solution under UV irradiation. In that TiO2-HMA nanocomposite showed superior photocatalytic activity than TiO2-HWA.

Versatile Peptide Dendrimers for Nucleic Acid Delivery

Dendrimers are nonviral vectors that have attracted interest on account of a number of features. They are structurally versatile because their size, shape, and surface charge can be selectively altered. Here we examine the functions of a new family of composite dendrimers that were synthesized with lipidic amino acid cores. These dendrimers are bifunctional because they are characterized by positively charged (lysine) modules for interaction with nucleic acids and neutral lipidic moieties for membrane lipid-bilayer transit. We assessed their structure-function correlations by a combination of molecular and biophysical techniques. Our assessment revealed an unexpected pleitropy of functions subserved by these vectors that included plasmid and oligonucleotide delivery. We also generated a firefly luciferase cell line in which we could modulate luciferase activity by RNA interference. We found that these vectors could also mediate RNA suppression of luciferase expression by delivering double-stranded luciferase transcripts generated in vitro. The structural uniqueness of these lipidic peptide dendrimers coupled with their ease and specificity of assembly and the versatility in their choice of cargo, puts them in a new category of macromolecule carriers. These vectors, therefore, have potential applications as epigenetic modifiers of gene function.

Adsorption of amphipathic dendrons on polystyrene nanoparticles

Adsorption of dendrons onto nanoparticles may provide new model structures which may be useful in drug and gene delivery. Tritiated amphipathic dendrons having three lipidic (C(14)) chains coupled to branched (dendritic) lysine head groups with 8, 16 or 32 free terminal amino groups have been synthesised by solid phase peptide techniques. The interaction between these tritiated dendrons and 200 nm polystyrene latex nanoparticles was investigated in phosphate buffered saline. The amount of dendron adsorbed increased with increasing concentration of dendrons and then decreased. Maximum adsorption of dendrons per gram of nanoparticles was found to be between 8.2 and 84 x 10(-6)M, the amounts adsorbed being inversely proportional to the number of amino groups present in the molecule. The number of dendron molecules adsorbed per nanoparticle was found to be between 430 and 4421. The degree of adsorption was found to be slightly altered by the temperature.

Interaction of cationic partial dendrimers with charged and neutral liposomes

Amphipathic partial dendrimers having three lipidic (C(14)) chains coupled to dendritic lysine head groups with eight, 16 or 32 free terminal amino groups have been synthesised by solid-phase peptide synthesis. Liposomes were prepared with positive, negative and neutral charge using the dehydration-rehydration method and their interaction with the partial dendrimers studied. The interaction efficiency of the partial cationic dendrimers studied was greater than 88%. Interaction of the cationic partial dendrimer converted liposomes with very low or negative charge into positively charged species. Apparent vesicle size increased with the head size of the partial dendrimer but, in the case of negatively charged liposomes, large changes in properties were observed after ultracentrifugation due to the formation of myelin figures. To investigate the mode of interaction with the liposomes, adsorption studies were performed by adding the partial dendrimer after the preparation of dehydration-rehydration vesicles. The results indicated that adsorption is inversely proportional to the head size of the partial dendrimer molecules and the extent of adsorption was similar on both positively and negatively charged liposomes. Adsorption produced liposomes with greater or similar zeta potentials to liposomes that incorporated partial dendrimer through the dehydration-rehydration method. Taking account of the different interaction efficiencies, this suggests there is a degree of partial dendrimer entrappment inside the liposomes.

Non-aqueous emulsions: hydrocarbon-formamide systems

There are few reports in the literature on formulation of non-aqueous emulsions. This study was designed to evaluate some design criteria for such systems. Formamide is the closest polar solvent that has the ability to replace water in emulsification when employing established non-ionic surfactants as stabilisers. For the majority of studies, linear alkanes (C6-C16) were dispersed in formamide as the continuous phase were stabilised with polysorbate 20. Initial studies involved gentle emulsification and observing mean globule size. The mean globule size varied in a non-linear fashion with alkyl chain length, the minimum being between C10 and C12. Sonication for 30 s led to smaller differences in the mean globule size. The effect of various parameters such as surfactant concentration and solvophilicity of the surfactant was observed. The surface activities of polysorbate 20, 40, 60 and 80 in formamide and critical micellar concentrations were determined. The latter were several orders of magnitude higher in formamide than in water, and the areas per molecule larger. The addition of water to the dodecane formamide systems did not destabilise the emulsion. Release of the model drug dehydroepiandrosterone from dodecane in formamide emulsions was studied in distilled water, the rate of release being dependent on the volume fraction of dodecane.

Interfacial behaviour and micelle formation of novel amphiphilic sequential lipid-lysine oligomers

As part of work on the design and synthesis of new supramolecular carrier systems for drugs, a series of novel linear oligomers of alternating alpha-amino tetradecanoic acid and lysine having positively charged groups and lipid chains was synthesised. The smallest member of the series (n=2) is insoluble in water and diluted acid solutions, but the larger members are soluble in acid conditions and poorly soluble in alkaline conditions. Hence, in one series, one can conduct experiments both on the determination of micelle formation and spread monolayer behaviour. The surface pressure-area isotherms revealed limiting surface areas at the air/water interface ranged from 0.04 to 0.9 nm(2) according to the oligomer size, and a linear correlation between the observed area per molecule and that projected by computer-generated molecular models was demonstrated. The surface tension of the soluble members in dilute acid solution fell as the concentration of the oligomers was increased, indicating that all of these polymers were surface active with quite clearly defined critical micelle concentrations. The fluorescence intensity ratio of third to first band in the emission spectra of pyrene as a function of the polymer concentrations demonstrated that, even after normalising the data for the amount of lipid chains in the system, the (n=3) oligomer had fewer accessible hydrophobic sites for pyrene, and the forces of the repulsion between the charged head groups was crucial on the formation of micelles, especially in the case of the n=3 oligomer. Supramolecular fibre-like structures were observed in aqueous solution only when n=3 by transmission electron microscopy (TEM). Cryogenic TEM observation of the (n=3) solution also revealed that the micelles might elongate to form long cylindrical or fibrous structures. The diameter of these structures was estimated to be 6.0-13 nm, although their length varied.

DNA transfection and transfected cell viability using amphipathic asymmetric dendrimers

Amphipathic asymmetric dendrimers have been investigated for use in delivery of genes into cells, with the objective of optimising transfection efficiency and maintaining cell viability. We have synthesised amphipathic asymmetric dendrimers by solid phase methods. The ability of two of these to transfect BHK cells in culture with beta-galactosidase gene was determined by X-gal staining. Cell viability was measured by the MTT assay for BHK cells, and by spectroscopy for lysis of erythrocytes. Interactions between dendrimer and DNA were investigated by agarose gel electrophoresis. BHK cells were optimally transfected at 5:1 +/- charge ratio yielding 20% cells receiving at least one copy of the plasmid. Cell viability decreased when the dendrimer to DNA ratio exceeded 5:1. Raising the pH significantly affected the electrophoretic mobility of complexes of dendrimer and DNA. We conclude that amphipathic asymmetric dendrimers enable efficient plasmid DNA uptake into BHK cells. Cell viability is maintained at high concentrations of dendrimer when complexed with DNA at a 5:1 +/- charge ratio. Efficiency of transfection and cell viability suggest the system may be suitable for gene delivery in vivo.

Oral uptake and translocation of a polylysine dendrimer with a lipid surface

A series of lipidic peptide dendrimers based on lysine with 16 surface alkyl (C(12)) chains has been synthesised in our laboratories. One of the series, a fourth generation dendrimer with a diameter of 2.5 nm was chosen to study its absorption after oral administration to female Sprague-Dawley rats (180 g, 9 weeks old). It was synthesised as the tritiated derivative (all acetyl portions) and had a molecular weight of 6300 and log P (octanol/water) of 1.24. First a single oral dose 14 mg/kg was administered by gavage. Maximum levels of dendrimer observed were 15% in the small intestine, 5% in the large intestine and 3% in the blood at 6 h after administration, while 1.5% reached the liver, 0.1% the spleen and 0. 5% the kidneys. In a parallel study with a higher dose of 28 mg/kg, approximately 1% was absorbed via Peyer's patches of the small intestine at 3 h. The maximum uptake by small intestine enterocytes was 4% of the dose after 3 h. After 12 h, 0.3 and 4% dendrimer was measured respectively in Peyer's patches and enterocytes of the large intestine. When calculated on the basis of target tissue weight, the total percentage of the dose absorbed through Peyer's patches was greater than through normal enterocytes in the small intestine after 3 and 24 h, but the opposite was true in the large intestine. These levels of uptake and translocation are lower than those exhibited by polystyrene particles in the range from 50 to 3000 nm. This might suggest that there is an optimum size for nanoparticulate uptake by the gut.

Distribution of a lipidic 2.5 nm diameter dendrimer carrier after oral administration

The biodistribution of a lipidic peptide dendrimer has been studied after oral administration to female Sprague-Dawley rats (180 g, 9 weeks old). Uptake by gut epithelial tissue of the radiolabelled dendrimer molecule (mol. wt. 6300; diameter 2.5 nm; log P=1.24) was studied in rats after a single oral dose by gavage (14 mg/kg). The maximum levels of dendrimer observed were 3% (blood), 1.5% (liver), 0.1% (spleen), 0.5% (kidneys), 15% (small intestine) and 5% (large intestine). Approximately 6% of a single administered dose (28 mg/kg) was recovered from the entire gastrointestinal tract while 1% was absorbed via the small intestine lymphoid tissue after 3 h; after 12 h, 0.1% was detected. The maximum uptake by the non-lymphoid small intestine was 4% of the dose after 3 h. After 12 h, 0.3 and 4% dendrimer was measured in the lymphoid large intestine and the non-lymphoid large intestine, respectively. The total percentage of the administered dose absorbed through the lymphoid tissue was comparatively greater than through the non-lymphoid tissue of the small intestine with respect to organ weight after 3 and 24 h.

Synthesis and physicochemical properties of lipophilic polyamide dendrimers

PURPOSE

To synthesise symmetrical dendritic macromolecules with external lipid surfaces, to investigate their behaviour at the air-water interface and their ability to form supramolecular aggregates, and to gain an understanding of their potential as drug carriers.

METHODS

Dendrimeric compounds were synthesised with molecular weights ranging from 737 (1st generation dendrimer) to 25,246 (6th generation dendrimer) with carbon numbers ranging from 40 to 1404. The surface behaviour of these compounds was determined using spread films at the air/water interface on a Langmuir trough, and transmission electron microscopy was used to study the supramolecular aggregates formed by the more hydrophobic members of the series.

RESULTS

Dendrimers up to a maximum of 6 generations were synthesised. Surface saturation did not allow the completion of the synthesis of the 7th generation. The limiting surface areas at the air/water interface ranged from 0.4 nm2 to 16.1 nm2 values in good agreement with the areas derived from computer generated molecular models (0.5 nm2 to 14 nm2).

CONCLUSIONS

The synthesised dendrimers exhibited a linear relationship between area per molecule and the molecular weight of the compounds. A dendrimer with 16 lipoamino acid branches formed tubular supramolecular aggregates with a helical structure and dimensions in the long axis of 140-200 nm.

Pressurized pack-based liposomes for pulmonary targeting of isoprenaline--development and characterization

Pressurized packs containing a phospholipid and drug that permits in situ formation of liposomes following deposition of the aerosolized cloud in the respiratory tract have been investigated. Prepared pressure packs and preformed liposomes of different lipoidal contents were characterized for shape, size, lamellarity and percentage drug entrapment. Pressure packs were studied for airway penetration efficiency. The study revealed that pressure packs-derived liposomes containing isoprenaline were fairly comparable with preformed liposomes by the ether injection method. The liposomal charge was found to effect drug disposition. However, drug sustained action was recorded in the case of liposomal inhalation(s) as compared to plain drug inhalation. The pressure packs thus demonstrated therapeutic potentiality in lung targeting of isoprenaline, as well as avoiding the liposome stability problem.