ResearchPad - Biomedical Engineering https://www.researchpad.co Default RSS Feed en-us © 2020 Newgen KnowledgeWorks <![CDATA[Automatic Prediction of Atrial Fibrillation Based on Convolutional Neural Network Using a Short-term Normal Electrocardiogram Signal]]> https://www.researchpad.co/product?articleinfo=5c89510cd5eed0c4847a4fe5

Background

In this study, we propose a method for automatically predicting atrial fibrillation (AF) based on convolutional neural network (CNN) using a short-term normal electrocardiogram (ECG) signal.

Methods

We designed a CNN model and optimized it by dropout and normalization. One-dimensional convolution, max-pooling, and fully-connected multiple perceptron were used to analyze the short-term normal ECG. The ECG signal was preprocessed and segmented to train and evaluate the proposed CNN model. The training and test sets consisted of the two AF and one normal dataset from the MIT-BIH database.

Results

The proposed CNN model for the automatic prediction of AF achieved a high performance with a sensitivity of 98.6%, a specificity of 98.7%, and an accuracy of 98.7%.

Conclusion

The results show the possibility of automatically predicting AF based on the CNN model using a short-term normal ECG signal. The proposed CNN model for the automatic prediction of AF can be a helpful tool for the early diagnosis of AF in healthcare fields.

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<![CDATA[Reliability, Learnability and Efficiency of Two Tools for Cement Crowns Retrieval in Dentistry]]> https://www.researchpad.co/product?articleinfo=5c131d1bd5eed0c48498df65 ]]> <![CDATA[Natural Sensations Evoked in Distal Extremities Using Surface Electrical Stimulation]]> https://www.researchpad.co/product?articleinfo=5c131d1ad5eed0c48498df0d ]]> <![CDATA[PEGylated crushed gold shell-radiolabeled core nanoballs for in vivo tumor imaging with dual positron emission tomography and Cerenkov luminescent imaging]]> https://www.researchpad.co/product?articleinfo=5b58ec17463d7e5414116038

Background

Radioactive isotope-labeled gold nanomaterials have potential biomedical applications. Here, we report the synthesis and characterization of PEGylated crushed gold shell-radioactive iodide-124-labeled gold core nanoballs (PEG-124I-Au@AuCBs) for in vivo tumor imaging applications through combined positron emission tomography and Cerenkov luminescent imaging (PET/CLI).

Results

PEG-124I-Au@AuCBs showed high stability and sensitivity in various pH solutions, serum, and in vivo conditions and were not toxic to tested cells. Combined PET/CLI clearly revealed tumor lesions at 1 h after injection of particles, and both signals remained visible in tumor lesions at 24 h, consistent with the biodistribution results.

Conclusion

Taken together, the data provided strong evidence for the application of PEG-124I-Au@AuCBs as promising imaging agents in nuclear medicine imaging of various biological systems, particularly in cancer diagnosis.

Electronic supplementary material

The online version of this article (10.1186/s12951-018-0366-x) contains supplementary material, which is available to authorized users.

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<![CDATA[Tailoring drug release rates in hydrogel-based therapeutic delivery applications using graphene oxide]]> https://www.researchpad.co/product?articleinfo=5b4b8fb8463d7e78c2172e35

Graphene oxide (GO) is increasingly used for controlling mass diffusion in hydrogel-based drug delivery applications. On the macro-scale, the density of GO in the hydrogel is a critical parameter for modulating drug release. Here, we investigate the diffusion of a peptide drug through a network of GO membranes and GO-embedded hydrogels, modelled as porous matrices resembling both laminated and ‘house of cards’ structures. Our experiments use a therapeutic peptide and show a tunable nonlinear dependence of the peptide concentration upon time. We establish models using numerical simulations with a diffusion equation accounting for the photo-thermal degradation of fluorophores and an effective percolation model to simulate the experimental data. The modelling yields an interpretation of the control of drug diffusion through GO membranes, which is extended to the diffusion of the peptide in GO-embedded agarose hydrogels. Varying the density of micron-sized GO flakes allows for fine control of the drug diffusion. We further show that both GO density and size influence the drug release rate. The ability to tune the density of hydrogel-like GO membranes to control drug release rates has exciting implications to offer guidelines for tailoring drug release rates in hydrogel-based therapeutic delivery applications.

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<![CDATA[Langevin dynamics encapsulate the microscopic and emergent macroscopic properties of midge swarms]]> https://www.researchpad.co/product?articleinfo=5b4ac753463d7e6b46cb1927

In contrast to bird flocks, fish schools and animal herds, midge swarms maintain cohesion but do not possess global order. High-speed imaging techniques are now revealing that these swarms have surprising properties. Here, I show that simple models found on the Langevin equation are consistent with this wealth of recent observations. The models predict correctly that large accelerations, exceeding 10 g, will be common and they predict correctly the coexistence of core condensed phases surrounded by dilute vapour phases. The models also provide new insights into the influence of environmental conditions on swarm dynamics. They predict that correlations between midges increase the strength of the effective force binding the swarm together. This may explain why such correlations are absent in laboratory swarms but present in natural swarms which contend with the wind and other disturbances. Finally, the models predict that swarms have fluid-like macroscopic mechanical properties and will slosh rather than slide back and forth after being abruptly displaced. This prediction offers a promising avenue for future experimentation that goes beyond current quasi-static testing which has revealed solid-like responses.

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<![CDATA[Graphene oxide conjugated with polymers: a study of culture condition to determine whether a bacterial growth stimulant or an antimicrobial agent?]]> https://www.researchpad.co/product?articleinfo=5bf2b9bdd5eed0c48412c521

Background

The results showed that the deciding factor is the culture medium in which the bacteria and the graphene oxide (GO) are incubated at the initial manipulation step. These findings allow better use of GO and GO-based materials more and be able to clearly apply them in the field of biomedical nanotechnology.

Results

To study the use of GO sheets applied in the field of biomedical nanotechnology, this study determines whether GO-based materials [GO, GO-polyoxyalkyleneamine (POAA), and GO-chitosan] stimulate or inhibit bacterial growth in detail. It is found that it depends on whether the bacteria and GO-based materials are incubated with a nutrient at the initial step. This is a critical factor for the fortune of bacteria. GO stimulates bacterial growth and microbial proliferation for Gram-negative and Gram-positive bacteria and might also provide augmented surface attachment for both types of bacteria. When an external barrier that is composed of GO-based materials forms around the surface of the bacteria, it suppresses nutrients that are essential to microbial growth and simultaneously produces oxidative stress, which causes bacteria to die, regardless of whether they have an outer-membrane-Gram-negative-bacteria or lack an outer-membrane-Gram-positive-bacteria, even for high concentrations of biocompatible GO-POAA. The results also show that these GO-based materials are capable of inducing reactive oxygen species (ROS)-dependent oxidative stress on bacteria. Besides, GO-based materials may act as a biofilm, so it is hypothesized that they suppress the toxicity of low-dose chitosan.

Conclusion

Graphene oxide is not an antimicrobial material but it is a general growth enhancer that can act as a biofilm to enhance bacterial attachment and proliferation. However, GO-based materials are capable of inducing ROS-dependent oxidative stress on bacteria. The applications of GO-based materials can clearly be used in antimicrobial surface coatings, surface-attached stem cells for orthopedics, antifouling for biocides and microbial fuel cells and microbial electro-synthesis.

Electronic supplementary material

The online version of this article (10.1186/s12951-017-0328-8) contains supplementary material, which is available to authorized users.

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<![CDATA[Host population structure and treatment frequency maintain balancing selection on drug resistance]]> https://www.researchpad.co/product?articleinfo=5b42fdd7463d7e1fd6df59cf

It is a truism that antimicrobial drugs select for resistance, but explaining pathogen- and population-specific variation in patterns of resistance remains an open problem. Like other common commensals, Streptococcus pneumoniae has demonstrated persistent coexistence of drug-sensitive and drug-resistant strains. Theoretically, this outcome is unlikely. We modelled the dynamics of competing strains of S. pneumoniae to investigate the impact of transmission dynamics and treatment-induced selective pressures on the probability of stable coexistence. We find that the outcome of competition is extremely sensitive to structure in the host population, although coexistence can arise from age-assortative transmission models with age-varying rates of antibiotic use. Moreover, we find that the selective pressure from antibiotics arises not so much from the rate of antibiotic use per se but from the frequency of treatment: frequent antibiotic therapy disproportionately impacts the fitness of sensitive strains. This same phenomenon explains why serotypes with longer durations of carriage tend to be more resistant. These dynamics may apply to other potentially pathogenic, microbial commensals and highlight how population structure, which is often omitted from models, can have a large impact.

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<![CDATA[Multiexcitation Fluorogenic Labeling of Surface, Intracellular, and Total Protein Pools in Living Cells]]> https://www.researchpad.co/product?articleinfo=5be2bbdcd5eed0c4843050b9

bc-2016-00169k_0006

Malachite green (MG) is a fluorogenic dye that shows fluorescence enhancement upon binding to its engineered cognate protein, a fluorogen activating protein (FAP). Energy transfer donors such as cyanine and rhodamine dyes have been conjugated with MG to modify the spectral properties of the fluorescent complexes, where the donor dyes transfer energy through Förster resonance energy transfer to the MG complex resulting in binding-conditional fluorescence emission in the far-red region. In this article, we use a violet-excitable dye as a donor to sensitize the far-red emission of the MG-FAP complex. Two blue emitting fluorescent coumarin dyes were coupled to MG and evaluated for energy transfer to the MG-FAP complex via its secondary excitation band. 6,8-Difluoro-7-hydroxycoumarin-3-carboxylic acid (Pacific blue, PB) showed the most efficient energy transfer and maximum brightness in the far-red region upon violet (405 nm) excitation. These blue-red (BluR) tandem dyes are spectrally varied from other tandem dyes and are able to produce fluorescence images of the MG-FAP complex with a large Stokes shift (>250 nm). These dyes are cell-permeable and are used to label intracellular proteins. Used together with a cell-impermeable hexa-Cy3-MG (HCM) dye that labels extracellular proteins, we are able to visualize extracellular, intracellular, and total pools of cellular protein using one fluorogenic tag that combines with distinct dyes to effect different spectral characteristics.

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<![CDATA[Efficient Synthesis of Nicotinamide-1-15N for Ultrafast NMR Hyperpolarization Using Parahydrogen]]> https://www.researchpad.co/product?articleinfo=5bd8bbe0d5eed0c48419efe8

bc-2016-00148s_0003

Nicotinamide (a vitamin B3 amide) is one of the key vitamins as well as a drug for treatment of M. tuberculosis, HIV, cancer, and other diseases. Here, an improved Zincke reaction methodology is presented allowing for straightforward and scalable synthesis of nicotinamide-1-15N with an excellent isotopic purity (98%) and good yield (55%). 15N nuclear spin label in nicotinamide-1-15N can be NMR hyperpolarized in seconds using parahydrogen gas. NMR hyperpolarization using the process of temporary conjugation between parahydrogen and to-be-hyperpolarized biomolecule on hexacoordinate iridium complex via the Signal Amplification By Reversible Exchange (SABRE) method significantly increases detection sensitivity (e.g., >20 000-fold for nicotinamide-1-15N at 9.4 T) as has been shown by Theis T. et al. (J. Am. Chem. Soc.2015, 137, 1404), and hyperpolarized in this fashion, nicotinamide-1-15N can be potentially used to probe metabolic processes in vivo in future studies. Moreover, the presented synthetic methodology utilizes mild reaction conditions, and therefore can also be potentially applied to synthesis of a wide range of 15N-enriched N-heterocycles that can be used as hyperpolarized contrast agents for future in vivo molecular imaging studies.

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<![CDATA[Using collision cones to assess biological deconfliction methods]]> https://www.researchpad.co/product?articleinfo=5bd0736440307c749edd8f0e

Biological systems consistently outperform autonomous systems governed by engineered algorithms in their ability to reactively avoid collisions. To better understand this discrepancy, a collision avoidance algorithm was applied to frames of digitized video trajectory data from bats, swallows and fish (Myotis velifer, Petrochelidon pyrrhonota and Danio aequipinnatus). Information available from visual cues, specifically relative position and velocity, was provided to the algorithm which used this information to define collision cones that allowed the algorithm to find a safe velocity requiring minimal deviation from the original velocity. The subset of obstacles provided to the algorithm was determined by the animal's sensing range in terms of metric and topological distance. The algorithmic calculated velocities showed good agreement with observed biological velocities, indicating that the algorithm was an informative basis for comparison with the three species and could potentially be improved for engineered applications with further study.

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<![CDATA[Local modulation of chemoattractant concentrations by single cells: dissection using a bulk-surface computational model]]> https://www.researchpad.co/product?articleinfo=5bcffa0540307c37826e787d

Chemoattractant gradients are usually considered in terms of sources and sinks that are independent of the chemotactic cell. However, recent interest has focused on ‘self-generated’ gradients, in which cell populations create their own local gradients as they move. Here, we consider the interplay between chemoattractants and single cells. To achieve this, we extend a recently developed computational model to incorporate breakdown of extracellular attractants by membrane-bound enzymes. Model equations are parametrized, using the published estimates from Dictyostelium cells chemotaxing towards cyclic AMP. We find that individual cells can substantially modulate their local attractant field under physiologically appropriate conditions of attractant and enzymes. This means the attractant concentration perceived by receptors can be a small fraction of the ambient concentration. This allows efficient chemotaxis in chemoattractant concentrations that would be saturating without local breakdown. Similar interactions in which cells locally mould a stimulus could function in many types of directed cell motility, including haptotaxis, durotaxis and even electrotaxis.

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<![CDATA[How chimpanzees integrate sensory information to select figs]]> https://www.researchpad.co/product?articleinfo=5bcb174140307c7bb5f60844 <![CDATA[Effects of the Alternate Combination of “Error-Enhancing” and “Active Assistive” Robot-Mediated Treatments on Stroke Patients]]> https://www.researchpad.co/product?articleinfo=5bca2ed640307c767ed7dcb6 <![CDATA[Rapid, Affordable, and Point-of-Care Water Monitoring Via a Microfluidic DNA Sensor and a Mobile Interface for Global Health]]> https://www.researchpad.co/product?articleinfo=5bca2ee440307c767ed7dcbb <![CDATA[A Non-Invasive Method for Estimating Cardiopulmonary Variables Using Breath-by-Breath Injection of Two Tracer Gases]]> https://www.researchpad.co/product?articleinfo=5bca2ee040307c767ed7dcba <![CDATA[Evaluating Innovative In-Ear Pulse Oximetry for Unobtrusive Cardiovascular and Pulmonary Monitoring During Sleep]]> https://www.researchpad.co/product?articleinfo=5bca2edd40307c767ed7dcb9 <![CDATA[Wireless Wearable Multisensory Suite and Real-Time Prediction of Obstructive Sleep Apnea Episodes]]> https://www.researchpad.co/product?articleinfo=5bca2ed840307c767ed7dcb7 <![CDATA[Non-Linear Dynamic Analysis of Inter-Word Time Intervals in Psychotic Speech]]> https://www.researchpad.co/product?articleinfo=5bca2edb40307c767ed7dcb8 <![CDATA[Authors' Index]]> https://www.researchpad.co/product?articleinfo=5bc90b7940307c65c3ed93f0