-
Revista de Gastroenterologia de Mexico... 2022Endoscopic submucosal dissection (ESD) is a well-established treatment for superficial gastrointestinal tumors and enables en bloc resection. Adequate tissue tension is...
INTRODUCTION AND AIMS
Endoscopic submucosal dissection (ESD) is a well-established treatment for superficial gastrointestinal tumors and enables en bloc resection. Adequate tissue tension is important for safe and effective dissection. Simplified magnetic anchor-guided ESD (MAG-ESD) with a neodymium magnet has potential benefits, compared with other current traction methods. We evaluated the feasibility of simplified MAG-ESD in an ex vivo porcine model.
MATERIALS AND METHODS
An experimental study was conducted, utilizing the standard ESD technique. An external magnet and an internal magnet, both neodymium magnets, were used for the magnetic anchoring. The internal magnet was attached to an arm of a hemoclip with a 2-0 silk suture. After the incision, the clip with the internal magnet was placed at the edge of the lesion. The external magnet was maneuvered around the surface to apply adequate tension.
RESULTS
A total of 15 en bloc ESDs (5 with no magnetic anchoring and 10 with magnetic anchoring) were carried out. Traction and dissection were feasible in all cases and the procedures were completed in fewer than 90min. Lesion size ranged from 15 to 50mm (mean 30mm). Two cases in the group with magnetic anchoring presented with punctate perforation (13.3%).
CONCLUSIONS
Our study demonstrated the feasibility of simplified MAG-ESD and en bloc resection in an ex vivo porcine model.
Topics: Animals; Dissection; Endoscopic Mucosal Resection; Humans; Magnetic Phenomena; Magnets; Neodymium; Swine
PubMed: 35090672
DOI: 10.1016/j.rgmxen.2021.03.002 -
International Journal of Molecular... Apr 2015In this review, we discuss the recent advances in and problems with the use of magnetically-guided and magnetically-responsive nanoparticles in drug delivery and... (Review)
Review
In this review, we discuss the recent advances in and problems with the use of magnetically-guided and magnetically-responsive nanoparticles in drug delivery and magnetofection. In magnetically-guided nanoparticles, a constant external magnetic field is used to transport magnetic nanoparticles loaded with drugs to a specific site within the body or to increase the transfection capacity. Magnetofection is the delivery of nucleic acids under the influence of a magnetic field acting on nucleic acid vectors that are associated with magnetic nanoparticles. In magnetically-responsive nanoparticles, magnetic nanoparticles are encapsulated or embedded in a larger colloidal structure that carries a drug. In this last case, an alternating magnetic field can modify the structure of the colloid, thereby providing spatial and temporal control over drug release.
Topics: Animals; Drug Delivery Systems; Ferric Compounds; Genetic Vectors; Humans; Magnetics; Magnetite Nanoparticles; Nucleic Acids; Transfection
PubMed: 25867479
DOI: 10.3390/ijms16048070 -
Journal of Magnetic Resonance (San... Nov 2021Small animal radiation experiments are of paramount importance for the advancement of human radiation therapy. These experiments use a dedicated radiation platform to...
Small animal radiation experiments are of paramount importance for the advancement of human radiation therapy. These experiments use a dedicated radiation platform to deliver radiation to small animals, such as mice and rats, similar to how human radiation therapy is performed. By acquiring images immediately before radiation delivery to guide positioning of the animals, image guidance plays a critical role to ensure accuracy of the experiments. Recently, MR-based image guidance has been enabled in human radiation therapy. This paper proposes a new concept using a unilateral magnet-based MRI scanner to realize image guidance for small animal radiation experiments. We reported our design, optimization, construction, and characterization of the magnet. The magnet was designed using eight 2-inch neodymium magnet cubes arranged in a modified Halbach ring configuration. The ring has an opening to allow for animal positioning. We considered a spherical region of interest (ROI) located outside of the ring's plane to allow radiation delivery to the ROI without obstruction of the magnet. An optimization problem was formulated and solved to determine the positions and orientations of the magnet cubes to generate a magnetic field with desired properties in the ROI. The optimization improved the average magnetic flux density from 55 mT to 72 mT and reduced variation from 1.2 T/m to 1.0 T/m. We constructed the magnet using 3D-printed templates to hold the neodymium magnet cubes with the optimized positions and orientations. We measured the spatial distribution of the magnetic flux density. The measurement results and computed results agreed with an average difference of 0.35% through the ROI.
Topics: Animals; Magnetic Fields; Magnetic Resonance Imaging; Magnets; Mice; Rats
PubMed: 34601187
DOI: 10.1016/j.jmr.2021.107062 -
Anales de Pediatria Nov 2022The ingestion of magnetic objects can cause complications in children, and there are no epidemiological or clinical data on the subject in Spain. (Observational Study)
Observational Study
INTRODUCTION
The ingestion of magnetic objects can cause complications in children, and there are no epidemiological or clinical data on the subject in Spain.
OBJECTIVES
To determine the incidence, epidemiological characteristics and management of magnet ingestion in paediatric emergency departments in Spain.
MATERIAL AND METHODS
Prospective observational multicentre study conducted over a 3-year period. The study universe consisted of patients aged less than 14 years.
RESULTS
The incidence was 4.8 cases per 100 000 emergency care episodes. Of the 72 patients included (mean age, 7.2 years), 54% were male. Seven percent had neuropsychiatric disorders. Sixty-one percent of the magnets were spherical and 69% came from toys. The size was variable, most frequently between 5 and 10 mm (50%), and ranging from 3 to 30 mm. Eighty-six percent of patients were asymptomatic. The most frequent symptom was abdominal pain. Eighty-three percent of the patients sought medical care within 6 h of ingestion and 92% within 24 h. Thirty-one percent of the cases were of multiple ingestion. Endoscopy was required for extraction in 15% of cases, a proportion that rose to 36% in the group of cases of multiple ingestion. None of the patients required surgery. We did not observe any gastrointestinal complications of magnet ingestion.
CONCLUSIONS
The ingestion of multiple magnets is less frequent than single magnet ingestion, and we did not observe any complications despite the lower frequency of procedures compared to other studies.
Topics: Child; Humans; Male; Female; Magnets; Foreign Bodies; Prospective Studies; Retrospective Studies; Endoscopy, Gastrointestinal; Emergency Service, Hospital; Eating
PubMed: 36115782
DOI: 10.1016/j.anpede.2022.09.001 -
World Journal of Gastroenterology Apr 2017Endoscopic submucosal dissection (ESD) is a well-established, minimally invasive treatment for superficial neoplasms of the gastrointestinal tract. The universal... (Review)
Review
Endoscopic submucosal dissection (ESD) is a well-established, minimally invasive treatment for superficial neoplasms of the gastrointestinal tract. The universal adoption of ESD has been limited by its slow learning curve, long procedure times, and high risk of complications. One technical challenge is the lack of a second hand that can provide traction, as in conventional surgery. Reliable tissue retraction that exposes the submucosal plane of dissection would allow for safer and more efficient dissection. Magnetic anchor guided endoscopic submucosal dissection (MAG-ESD) has potential benefits compared to other current traction methods. MAG-ESD offers tissue retraction independent of the endoscope mimicking a surgeon's "second hand". Two types of magnets can be used: electromagnets and permanent magnets. In this article we review the MAG-ESD technology, published work and studies of magnets in ESD. We also review the use of magnetic anchor guidance systems in natural orifice transluminal endoscopic surgery and the idea of magnetic non-contact retraction using surface ferromagentization. We discuss the current limitations, the future potential of MAG-ESD and the developments needed for adoption of this technology.
Topics: Animals; Endoscopic Mucosal Resection; Equipment Design; Gastrointestinal Neoplasms; Humans; Magnetics; Magnets; Natural Orifice Endoscopic Surgery; Treatment Outcome
PubMed: 28522906
DOI: 10.3748/wjg.v23.i16.2883 -
Journal (Canadian Dental Association) 2010Open-field aluminum-nickle-cobalt magnets have been used in prosthodontics for many years, but success has been limited because these magnets are susceptible to... (Review)
Review
Open-field aluminum-nickle-cobalt magnets have been used in prosthodontics for many years, but success has been limited because these magnets are susceptible to corrosion by the saliva and because their retentive force is weak relative to the initial retention offered by mechanical attachments. More recently, magnets have been made from alloys of the rare earth elements samarium and neodymium, which provide stronger magnetic force per unit size. In addition, a new generation of laser-welded containers has improved protection from salivary corrosion. The current resurgence of interest in this type of attachment appears justified because, unlike mechanical attachments, magnets have potential for unlimited durability and might therefore be superior to mechanical ball or bar attachments for the retention of removable prostheses on implants. To date, no long-term prospective trials have been conducted to confirm the clinical durability of this new generation of magnets for retaining dentures on either teeth or implants. The aim of this study was to document initial clinical experiences and levels of satisfaction among edentulous patients treated with mandibular implant-supported overdentures retained using a new generation of rare-earth magnetic attachments. At the outset, all but one of the 17 patients had had several years of experience with implant-supported overdentures. During the first year, the mean overall satisfaction among these 17 patients increased from less than 70 to over 90 out of 100 (standardized visual analogue scale). No unusual difficulties were encountered in rendering the treatment or maintaining the attachments. This report offers preliminary evidence of the excellent potential of these magnets for retaining mandibular implant-supported overdentures.
Topics: Contraindications; Corrosion; Dental Plaque; Dental Prosthesis, Implant-Supported; Dental Soldering; Denture Retention; Denture, Overlay; Humans; Lasers; Magnetic Resonance Imaging; Magnetics; Mandible; Neodymium; Patient Satisfaction; Samarium; Welding
PubMed: 20943036
DOI: No ID Found -
NMR in Biomedicine Aug 2022Prepolarized MRI (PMRI) is a long-established technique conceived to counteract the loss in signal-to-noise ratio (SNR) inherent to low-field MRI systems. When it comes...
Prepolarized MRI (PMRI) is a long-established technique conceived to counteract the loss in signal-to-noise ratio (SNR) inherent to low-field MRI systems. When it comes to hard biological tissues and solid-state matter, PMRI is severely restricted by their ultra-short characteristic relaxation times. Here we demonstrate that efficient hard-tissue prepolarization is within reach with a special-purpose 0.26 T scanner designed for ex vivo dental MRI and equipped with suitable high-power electronics. We have characterized the performance of a 0.5 T prepolarizer module, which can be switched on and off in 200 μs. To this end, we have used resin, dental and bone samples, all with times of the order of 20 ms at our field strength. The measured SNR enhancement is in good agreement with a simple theoretical model, and deviations in extreme regimes can be attributed to mechanical vibrations due to the magnetic interaction between the prepolarization and main magnets.
Topics: Magnetic Resonance Imaging; Magnetics; Magnets; Models, Theoretical; Signal-To-Noise Ratio
PubMed: 35384092
DOI: 10.1002/nbm.4737 -
BMC Medical Imaging May 2020We suspected that moving a small neodymium magnet would promote migration of the magnetic tracer to the sentinel lymph node (SLN). Higher monitoring counts on the skin... (Clinical Trial)
Clinical Trial
BACKGROUND
We suspected that moving a small neodymium magnet would promote migration of the magnetic tracer to the sentinel lymph node (SLN). Higher monitoring counts on the skin surface before making an incision help us detect SLNs easily and successfully. The present study evaluated the enhancement of the monitoring count on the skin surface in SLN detection based on the magnet movement in a sentinel lymph node biopsy (SNB) using superparamagnetic iron oxide (SPIO) nanoparticles.
METHODS
After induction of general anesthesia, superparamagnetic iron oxide nanoparticles were injected sub-dermally into the subareolar area or peritumorally. The neodymium magnet was moved over the skin from the injection site to the axilla to promote migration of the magnetic tracer without massage. A total of 62 patients were enrolled from February 2018 to November 2018: 13 cases were subjected to magnet movement 20 times (Group A), 8 were subjected to 1-min magnet movement (Group B), 26 were given a short (about 5 min) interval from injection to 1-min magnet movement (Group C), and 15 were given a long (about 25 min) interval before 1-min magnet movement using the magnetometer's head (Group D). In all cases, an SNB was conducted using both the radioisotope (RI) and SPIO methods. The monitoring counts on the skin surface were measured by a handheld magnetometer and compared among the four groups. Changes in the monitoring count by the interval and magnet movement were evaluated.
RESULTS
The identification rates of the SPIO and RI methods were 100 and 95.2%, respectively. The mean monitoring counts of Group A, B, C, and D were 2.39 μT, 2.73 μT, 3.15 μT, and 3.92 μT, respectively (p < 0.0001; Kruskal-Wallis test). The monitoring counts were higher with longer magnet movement and with the insertion of an interval. Although there were no relationships between the monitoring count on the skin surface and clinicopathologic factors, magnet movement strongly influenced the monitoring count on the skin surface.
CONCLUSION
Moving a small neodymium magnet is effective for promoting migration of a magnetic tracer and increasing monitoring counts on the skin surface.
TRIAL REGISTRATION
UMIN, UMIN000029475. Registered 9 October 2017.
Topics: Adult; Aged; Breast Neoplasms; Female; Humans; Magnetic Iron Oxide Nanoparticles; Magnetic Phenomena; Magnets; Middle Aged; Neodymium; Sentinel Lymph Node; Sentinel Lymph Node Biopsy
PubMed: 32460834
DOI: 10.1186/s12880-020-00459-2 -
International Journal of Molecular... Nov 2016Protein crystallization under a magnetic field is an interesting research topic because a magnetic field may provide a special environment to acquire improved quality... (Review)
Review
Protein crystallization under a magnetic field is an interesting research topic because a magnetic field may provide a special environment to acquire improved quality protein crystals. Because high-quality protein crystals are very useful in high-resolution structure determination using diffraction techniques (X-ray, neutron, and electron diffraction), research using magnetic fields in protein crystallization has attracted substantial interest; some studies have been performed in the past two decades. In this research field, the hardware is especially essential for successful studies because the environment is special and the design and utilization of the research apparatus in such an environment requires special considerations related to the magnetic field. This paper reviews the hardware for protein crystallization (including the magnet systems and the apparatus designed for use in a magnetic field) and progress in this area. Future prospects in this field will also be discussed.
Topics: Animals; Crystallization; Equipment Design; Humans; Magnetic Fields; Magnetics; Proteins
PubMed: 27854318
DOI: 10.3390/ijms17111906 -
Nano Letters Aug 2021The mechanical environment of a cell is not constant. This dynamic behavior is exceedingly difficult to capture in (synthetic) matrices. This paper describes a novel,...
The mechanical environment of a cell is not constant. This dynamic behavior is exceedingly difficult to capture in (synthetic) matrices. This paper describes a novel, highly adaptive hybrid hydrogel composed of magnetically sensitive magnetite nanorods and a stress-responsive synthetic matrix. Nanorod rearrangement after application of (small) magnetic fields induces strain in the network, which results in a strong (over 10-fold) stiffening even at minimal (2.5 wt %) nanorod concentrations. Moreover, the stiffening mechanism yields a fast and fully reversible response. In the manuscript, we quantitatively analyze that forces generated by the particles are comparable to cellular forces. We demonstrate the value of magnetic stiffening in a 3D MCF10A epithelial cell experiment, where simply culturing on top of a permanent magnet gives rise to changes in the cell morphology. This work shows that our hydrogels are uniquely suited as 3D cell culture systems with on-demand adaptive mechanical properties.
Topics: Cell Culture Techniques; Hydrogels; Magnetic Phenomena; Magnetics; Stress, Mechanical
PubMed: 34387494
DOI: 10.1021/acs.nanolett.1c00371