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World Journal of Gastroenterology Jul 2015To explore the anatomical feasibility of portacaval shunt using a magnetic compression technique (MCT) in cadavers.
AIM
To explore the anatomical feasibility of portacaval shunt using a magnetic compression technique (MCT) in cadavers.
METHODS
Computed tomography (CT) images of 30 portal hypertensive patients were obtained. The diameters of the portal vein (PV), the inferior vena cava (IVC), and distance between the two structures were measured. Similar measurements were performed on 20 adult corpses. The feasibility of portacaval shunt based on those measurements was analyzed. First stage of the extrahepatic portacaval shunt using MCT was performed on five cadavers. Specifically, the PV and IVC were exposed through an abdominal incision of the cadavers. The parent magnet was introduced from the femoral vein and was delivered into the IVC by an anchor wire and a 5F Cook catheter. The daughter magnet was introduced into the PV through the splenic vein using an interventional guide wire. When the daughter magnet met the parent magnet, they automatically clipped together and the first stage of the portacaval shunt was set up.
RESULTS
The average diameters of the PV and the IVC measured from the 30 CT image were 14.39 ± 2.36 mm and 18.59 ± 4.97 mm, respectively, and the maximum and minimum distances between the PV and the IVC were 9.79 ± 4.56 mm and 9.50 ± 4.79 mm, respectively. From 20 cadavers, the average diameters of the PV and the IVC were 14.48 ± 1.47 mm and 24.71 ± 2.64 mm, and the maximum and minimum distances between the PV and the IVC were 10.14 ± 1.70 mm and 8.93 ± 1.17 mm, respectively. The distances between the PV and the IVC from both the CT images and the cadavers were within the effective length of portacaval anastomosis using MCT (30.30 ± 4.19 mm). The PV and IVC are in close proximity to each other with no intervening tissues or structures in between. Simulated surgeries of the first stage using MCT on five cadavers was successfully performed.
CONCLUSION
Anatomically, extrahepatic portacaval shunt employing MCT is highly feasible in humans.
Topics: Adult; Aged; Cadaver; Constriction; Equipment Design; Feasibility Studies; Female; Humans; Hypertension, Portal; Magnetics; Magnets; Male; Middle Aged; Multidetector Computed Tomography; Phlebography; Portacaval Shunt, Surgical; Portal Vein; Vena Cava, Inferior
PubMed: 26185378
DOI: 10.3748/wjg.v21.i26.8073 -
IUBMB Life Aug 2011Magnetic targeting has shown promise to improve the efficacy and safety of different classes of therapeutic agents by enabling their active guidance to the site of... (Review)
Review
Magnetic targeting has shown promise to improve the efficacy and safety of different classes of therapeutic agents by enabling their active guidance to the site of disease and minimizing dissemination to nontarget tissues. However, its translation into clinic has proven difficult because of inherent limitations of traditional approaches inapplicable for deep tissue targeting in human subjects and a need for developing well-characterized and fully biocompatible magnetic carrier formulations. A novel magnetic targeting scheme based on the magnetizing effect of deep-penetrating uniform fields is presented as an example of a strategy providing a potentially clinically viable solution for preventing injury-triggered reobstruction of stented blood vessels (in-stent restenosis). The design of optimized magnetic carrier formulations and experimental results showing the feasibility of uniform field-controlled targeting for site-specific vascular delivery of small-molecule pharmaceuticals, biotherapeutics, and cells are discussed in the context of antirestenotic therapy. The versatility of this approach applicable to different classes of therapeutic agents exerting their antirestenotic effects through distinct mechanisms prompts exploring the utility of uniform field-mediated magnetic stent targeting for combination therapies with enhanced efficiencies and improved safety profiles. Additional improvements in terms of site specificity and protracted carrier retention at the site of injury may be expected from the development and use of magnetic carriers exhibiting affinity for arterial wall-specific antigens.
Topics: Blood Vessels; Humans; Magnetics; Nanoparticles
PubMed: 21721100
DOI: 10.1002/iub.479 -
BMJ Case Reports Mar 2014A 17-year-old girl was admitted with acute abdominal pain, vomiting and a leucocytosis, and was initially thought to have appendicitis. She underwent laparoscopic...
A 17-year-old girl was admitted with acute abdominal pain, vomiting and a leucocytosis, and was initially thought to have appendicitis. She underwent laparoscopic appendicectomy, where the tip of the appendix was noted to be mildly inflamed and she was discharged home the day after surgery. Two days later, she re-presented with small bowel obstruction which was subsequently demonstrated to be due to ingestion of five magnetic beads. She required a laparotomy and small bowel resection to resolve the obstruction, but has since fully recovered. This case highlights the potential intestinal complications caused by the intake of magnetic objects, and based on a literature review a number of recommendations are made to guide clinicians when managing similar cases.
Topics: Adolescent; Appendicitis; Diagnosis, Differential; Female; Foreign Bodies; Humans; Intestinal Obstruction; Intestine, Small; Magnets
PubMed: 24591386
DOI: 10.1136/bcr-2013-202794 -
International Journal of Molecular... May 2023Highly anisotropic single-molecule magnets (SMMs) have attracted much interest in the field of molecular magnetism because of their spin features and potential...
Highly anisotropic single-molecule magnets (SMMs) have attracted much interest in the field of molecular magnetism because of their spin features and potential technological applications. Additionally, a great effort has been devoted to the functionalization of such molecule-based systems which are made with ligands containing functional groups suitable to connect SMMs to junction devices or to perform their grafting on surfaces of different substrates. We have synthesized and characterized two lipoic acid-functionalized and oxime-based Mn(III) compounds, of formula [Mn(μ-O)(HN-sao)(lip)(MeOH)][Mn(μ-O)(HN-sao)(cnph)(MeOH)]}·10MeOH () and [Mn(μ-O)(HN-sao)(lip)(EtOH)]·EtOH·2HO () [HN-saoH = salicylamidoxime, lip = lipoate anion, cnph = 2-cyanophenolate anion]. Compound crystallizes in the space group ī of the triclinic system and crystallizes in the space group C2/c of the monoclinic system. In the crystal, neighboring Mn entities are linked using non-coordinating solvent molecules, which are H-bonded to N atoms of -NH groups of amidoxime ligand. In addition, Hirshfeld surfaces of and were calculated to study the variety of intermolecular interactions and the different levels of importance that take place in their crystal lattice; this type of computed study is the first time performed on Mn complexes. The study of the magnetic properties of and through dc magnetic susceptibility measurements reveals the coexistence of ferromagnetic and antiferromagnetic exchange couplings between the Mn(III) metal ions in both compounds, the latter being the predominant magnetic interaction. A spin S = 4 value of the ground state was obtained using isotropic simulations of the experimental magnetic susceptibility data for both and . Ac magnetic susceptibility measurements show features typical of slow relaxation of the magnetization in and , which indicate that SMM behavior takes place in both compounds.
Topics: Manganese; Thioctic Acid; Organometallic Compounds; Magnetics; Anions
PubMed: 37239996
DOI: 10.3390/ijms24108645 -
Molecules (Basel, Switzerland) May 2023Two mononuclear nickel(II) complexes of the formula [Ni(terpyCOOH)](ClO)∙4HO () and [Ni(terpyepy)](ClO) MeOH () [terpyCOOH = 4'-carboxyl-2,2':6',2″-terpyridine and...
Two mononuclear nickel(II) complexes of the formula [Ni(terpyCOOH)](ClO)∙4HO () and [Ni(terpyepy)](ClO) MeOH () [terpyCOOH = 4'-carboxyl-2,2':6',2″-terpyridine and terpyepy = 4'-[(2-pyridin-4-yl)ethynyl]-2,2':6',2″-terpyridine] have been prepared and their structures determined by single-crystal X-ray diffraction. Complexes and are mononuclear compounds, where the nickel(II) ions are six-coordinate by the six nitrogen atoms from two tridentate terpy moieties. The mean values of the equatorial Ni-N bond distances [2.11(1) and 2.12(1) Å for Ni(1) at and , respectively, are somewhat longer than the axial ones [2.008(6) and 2.003(6) Å ()/2.000(1) and 1.999(1) Å ()]. The values of the shortest intermolecular nickel-nickel separation are 9.422(1) () and 8.901(1) Å (). Variable-temperature (1.9-200 K) direct current (dc) magnetic susceptibility measurements on polycrystalline samples of and reveal a Curie law behavior in the high-temperature range, which corresponds to magnetically isolated spin triplets, the downturn of the χ product at lower temperatures being due to zero-field splitting effects (). Values of equal to -6.0 () and -4.7 cm () were obtained through the joint analysis of the magnetic susceptibility data and the field dependence of the magnetization. These results from magnetometry were supported by theoretical calculations. Alternating current (ac) magnetic susceptibility measurements of and in the temperature range 2.0-5.5 K show the occurrence of incipient out-phase signals under applied dc fields, a phenomenon that is characteristic of field-induced Single-Molecule Magnet (SMM) behavior, which herein concerns the 2 mononuclear nickel(II) complexes. This slow relaxation of the magnetization in and has its origin in the axial compression of the octahedral surrounding at their nickel(II) ions that leads to negative values of . A combination of an Orbach and a direct mechanism accounts for the field-dependent relation phenomena in and .
Topics: Nickel; Models, Molecular; Magnets; Crystallography, X-Ray; Ions
PubMed: 37298899
DOI: 10.3390/molecules28114423 -
Journal of the American Heart... Jun 2021Background Magnet wireless charging is being utilized increasingly in current generation smartphones. Apple's MagSafe is a proprietary wireless charging technology with...
Background Magnet wireless charging is being utilized increasingly in current generation smartphones. Apple's MagSafe is a proprietary wireless charging technology with an array of magnets that has the capacity to generate magnet fieldstrength >50 gauss (G). We hypothesize that there is clinically significant magnet interference caused by Apple's MagSafe technology on cardiac implantable electronic devices (CIED). Methods and Results This study has an in vivo and an ex vivo component. The in vivo component consists of consecutive patients who presented to the electrophysiology laboratory with previously implanted CIEDs. The iPhone 12 Pro Max was directly placed on the skin over the pocket of these patients and the effect was studied by device interrogation. For the ex vivo component of the study, CIEDs from major device companies were tested for magnetic interference caused by iPhone 12 Pro Max through unopened packages. We found that iPhone 12 Pro Max resulted in clinically identifiable magnet interference in 3/3 (100%) participants in vivo and in 8/11 (72.7%) devices ex vivo. Conclusions Apple's iPhone 12 Pro Max MagSafe technology can cause magnet interference on CIEDs and has the potential to inhibit lifesaving therapy.
Topics: Defibrillators, Implantable; Humans; Magnetic Fields; Magnets; Materials Testing; Pacemaker, Artificial; Prosthesis Failure; Risk Assessment; Risk Factors; Smartphone; Wireless Technology
PubMed: 34074132
DOI: 10.1161/JAHA.121.020818 -
Journal of Visualized Experiments : JoVE Jan 2018A spheroid culture is a useful tool for understanding cellular behavior in that it provides an in vivo-like three-dimensional environment. Various spheroid production...
A spheroid culture is a useful tool for understanding cellular behavior in that it provides an in vivo-like three-dimensional environment. Various spheroid production methods such as non-adhesive surfaces, spinner flasks, hanging drops, and microwells have been used in studies of cell-to-cell interaction, immune-activation, drug screening, stem cell differentiation, and organoid generation. Among these methods, microwells with a three-dimensional concave geometry have gained the attention of scientists and engineers, given their advantages of uniform-sized spheroid generation and the ease with which the responses of individual spheroids can be monitored. Even though cost-effective methods such as the use of flexible membranes and ice lithography have been proposed, these techniques incur serious drawbacks such as difficulty in controlling the pattern sizes, achievement of high aspect ratios, and production of larger areas of microwells. To overcome these problems, we propose a robust method for fabricating concave microwells without the need for complex high-cost facilities. This method utilizes a 30 x 30 through-hole array, several hundred micrometer-order steel beads, and magnetic force to fabricate 900 microwells in a 3 cm x 3 cm polydimethylsiloxane (PDMS) substrate. To demonstrate the applicability of our method to cell biological applications, we cultured adipose stem cells for 3 days and successfully produced spheroids using our microwell platform. In addition, we performed a magnetostatic simulation to investigate the mechanism, whereby magnetic force was used to trap the steel beads in the through-holes. We believe that the proposed microwell fabrication method could be applied to many spheroid-based cellular studies such as drug screening, tissue regeneration, stem cell differentiation, and cancer metastasis.
Topics: Cell Culture Techniques; Humans; Magnets; Spheroids, Cellular
PubMed: 29443026
DOI: 10.3791/55548 -
CMAJ : Canadian Medical Association... Sep 2007Static magnets are marketed with claims of effectiveness for reducing pain, although evidence of scientific principles or biological mechanisms to support such claims is... (Meta-Analysis)
Meta-Analysis Review
BACKGROUND
Static magnets are marketed with claims of effectiveness for reducing pain, although evidence of scientific principles or biological mechanisms to support such claims is limited. We performed a systematic review and meta-analysis to assess the clinical evidence from randomized trials of static magnets for treating pain.
METHODS
Systematic literature searches were conducted from inception to March 2007 for the following data sources: MEDLINE, EMBASE, AMED (Allied and Complementary Medicine Database), CINAHL, Scopus, the Cochrane Library and the UK National Research Register. All randomized clinical trials of static magnets for treating pain from any cause were considered. Trials were included only if they involved a placebo control or a weak magnet as the control, with pain as an outcome measure. The mean change in pain, as measured on a 100-mm visual analogue scale, was defined as the primary outcome and was used to assess the difference between static magnets and placebo.
RESULTS
Twenty-nine potentially relevant trials were identified. Nine randomized placebo-controlled trials assessing pain with a visual analogue scale were included in the main meta-analysis; analysis of these trials suggested no significant difference in pain reduction (weighted mean difference [on a 100-mm visual analogue scale] 2.1 mm, 95% confidence interval -1.8 to 5.9 mm, p = 0.29). This result was corroborated by sensitivity analyses excluding trials of acute effects and conditions other than musculoskeletal conditions. Analysis of trials that assessed pain with different scales suggested significant heterogeneity among the trials, which means that pooling these data is unreliable.
INTERPRETATION
The evidence does not support the use of static magnets for pain relief, and therefore magnets cannot be recommended as an effective treatment. For osteoarthritis, the evidence is insufficient to exclude a clinically important benefit, which creates an opportunity for further investigation.
Topics: Humans; Magnetics; Pain Management; Pain Measurement; Randomized Controlled Trials as Topic
PubMed: 17893349
DOI: 10.1503/cmaj.061344 -
Sensors (Basel, Switzerland) Mar 2021A magnetically-guided capsule endoscope, embedding flexible force sensors, is designed to measure the capsule-tissue interaction force. The flexible force sensor is...
A magnetically-guided capsule endoscope, embedding flexible force sensors, is designed to measure the capsule-tissue interaction force. The flexible force sensor is composed of eight force-sensitive elements surrounding the internal permanent magnet (IPM). The control of interaction force acting on the intestinal wall can reduce patient's discomfort and maintain the magnetic coupling between the external permanent magnet (EPM) and the IPM during capsule navigation. A flexible force sensor can achieve this control. In particular, by analyzing the signals of the force sensitive elements, we propose a method to recognize the status of the motion of the magnetic capsule, and provide corresponding formulas to evaluate whether the magnetic capsule follows the motion of the external driving magnet. Accuracy of the motion recognition in Ex Vivo tests reached 94% when the EPM was translated along the longitudinal axis. In addition, a method is proposed to realign the EPM and the IPM before the loss of their magnetic coupling. Its translational error, rotational error, and runtime are 7.04 ± 0.71 mm, 3.13 ± 0.47∘, and 11.4 ± 0.39 s, respectively. Finally, a control strategy is proposed to prevent the magnetic capsule endoscope from losing control during the magnetically-guided capsule colonoscopy.
Topics: Capsule Endoscopes; Equipment Design; Humans; Magnets; Mechanical Phenomena; Motion
PubMed: 33808443
DOI: 10.3390/s21072395 -
Nano Letters Dec 2022Nanometric topological spin textures, such as skyrmions (Sks) and antiskyrmions (antiSks), have attracted much attention recently. However, most studies have focused on...
Nanometric topological spin textures, such as skyrmions (Sks) and antiskyrmions (antiSks), have attracted much attention recently. However, most studies have focused on two-dimensional spin textures in films with inherent or synthetic antisymmetric spin-exchange interaction, termed Dzyaloshinskii-Moriya interaction, although three-dimensional (3D) topological spin textures, such as antiSks composed of alternating Bloch- and Néel-type spin spirals, chiral bobbers carrying emergent magnetic monopoles, and deformed Sk strings, are ubiquitous. To elucidate these textures, we have developed a 3D nanometric magnetic imaging technique, tomographic Lorentz transmission electron microscopy (TEM). The approach enables the visualization of the 3D shape of magnetic objects and their 3D vector field mapping. Here we report 3D vector field maps of deformed Sk-strings and antiSk using the technique. This research approach will lead to discoveries and understanding of fertile 3D magnetic structures in a broad class of magnets, providing insight into 3D topological magnetism.
Topics: Imaging, Three-Dimensional; Magnets; Microscopy, Electron, Transmission
PubMed: 36383503
DOI: 10.1021/acs.nanolett.2c03142