V pediatrické praxi přibývá případů polknutí magnetických cizích těles. Jde o magnetky ve tvaru kuliček, kostiček apod., které jsou součástí hraček. Tyto předměty jsou často drobné, a tím je usnadněno jejich náhodné polknutí. Přitom, pokud dojde k ingesci více než jednoho magnetického cizího tělesa, může dojít k závažným komplikacím, především ve smyslu perforace trávicího traktu.

The incidence of swalowing magnetic foreign bodies increases in children, often in the form of balls, cubes etc., which are part of toys. These magnets are often small, making it easy to accidentally swallow them. If more than one magnetic foreign body is ingested, serious complications can occur, especially perforation of the gastrointestinal tract.

• MeSH
• Digestive System Surgical Procedures methods   MeSH
• Foreign Bodies * surgery   MeSH
• Child MeSH
• Endoscopy, Gastrointestinal MeSH
• Humans MeSH
• Magnets MeSH
• Practice Guidelines as Topic MeSH
• Accidents, Home MeSH
• Check Tag
• Child MeSH
• Humans MeSH
• Female MeSH
• Publication type
• Case Reports MeSH
• Research Support, Non-U.S. Gov't MeSH

Magnetic beads (MBs) are versatile tools in the separation of nucleic acids, proteins and other biomacromolecules, their complexes and cells. In this article recent application of MBs in electrochemical biosensing and particularly in the development of DNA hybridization sensors is reviewed. In these sensors MBs serve not only for separation but also as a platform for optimized DNA hybridization. A hybridization event is detected separately at another surface, which is an electrode. The detection is based either on the intrinsic DNA electroactivity or on various kinds of DNA labeling, including chemical modification, enzyme tags, nanoparticles, electroactive beads, etc., greatly amplifying the signals measured. In addition to DNA hybridization, other kinds of biosensing in combination with MBs, such as DNA-protein interactions, are reviewed.

• MeSH
• Biosensing Techniques instrumentation   MeSH
• DNA analysis   genetics   MeSH
• Electrochemistry MeSH
• Financing, Organized MeSH
• Humans MeSH
• Magnetics MeSH
• Microspheres MeSH
• Nanostructures chemistry   MeSH
• Proteins analysis   immunology   metabolism   MeSH
• Check Tag
• Humans MeSH
• Publication type
• Review MeSH

Screen-printed platinum electrodes as transducer and magnetic beads as solid phase were combined to develop a particle-based electrochemical immunosensor for monitoring the serious food allergen ovalbumin. The standard arrangement of enzyme-linked immunosorbent assay became the basis for designing the immunosensor. A sandwich-type immunocomplex was formed between magnetic particles functionalized with specific anti-ovalbumin immunoglobulin G and captured ovalbumin molecules, and secondary anti-ovalbumin antibodies conjugated with the enzyme horseradish peroxidase were subsequently added as label tag. The electrochemical signal proportional to the enzymatic reaction of horseradish peroxidase during the reduction of hydrogen peroxide with thionine as electron mediator was measured by linear sweep voltammetry. The newly established method of ovalbumin detection exhibits high sensitivity suitable for quantification in the range of 11 to 222nM and a detection limit of 5nM. Magnetic beads-based assay format using external magnets for rapid and simple separation has been proven to be an excellent basis for electrochemical detection and quantification of food allergens in highly complex sample matrices.

• MeSH
• Biosensing Techniques instrumentation   methods   MeSH
• Electric Conductivity MeSH
• Electrochemistry MeSH
• Electrodes MeSH
• Antibodies, Immobilized chemistry   immunology   MeSH
• Immunoassay instrumentation   methods   MeSH
• Limit of Detection MeSH
• Magnets chemistry   MeSH
• Microspheres * MeSH
• Ovalbumin adverse effects   analysis   MeSH
• Platinum chemistry   MeSH
• Food Hypersensitivity metabolism   MeSH
• Electron Transport MeSH
• Animals MeSH
• Check Tag
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH

Superparamagnetic agents can be reliably used for magnetic resonance imaging (MRI) of pancreatic islets located in the liver sinusoids. However, the main disadvantages seemed to be the rather long culture time necessary for islet labeling and the low specificity of these agents. In the present study we investigated a more specific approach with a shorter labeling time using immunomagnetic particles. Isolated rat islets were cultivated with immunomagnetic beads coated with antibody against rat MHC class I antigen. Labeled islets were transplanted into the livers of syngeneic rats. The animals were examined weekly by MRI or livers explanted 10 minutes after islet transplantation for in vitro experiments. In both in vitro and in vivo studies, labeled transplanted islets were imaged as hypointensive spots, diffusely distributed throughout the liver. This experiment represents an alternative way of islet imaging by magnetic resonance, which is as effective as the use of known superparamagnetic contrast agents and more specific owing to targeting to specific donor antigens.

• MeSH
• Transplantation, Homologous methods   pathology   MeSH
• Liver * cytology   MeSH
• Rats MeSH
• Islets of Langerhans cytology   MeSH
• Magnetic Resonance Imaging MeSH
• Rats, Inbred Lew MeSH
• Rats, Wistar MeSH
• Islets of Langerhans Transplantation * methods   pathology   MeSH
• Animals MeSH
• Check Tag
• Rats MeSH
• Male MeSH
• Animals MeSH
• Publication type
• Research Support, Non-U.S. Gov't MeSH

DNA ligases are essential enzymes in all cells and have been proposed as targets for novel antibiotics. Efficient DNA ligase activity assays are thus required for applications in biomedical research. Here we present an enzyme-linked electrochemical assay based on two terminally tagged probes forming a nicked junction upon hybridization with a template DNA. Nicked DNA bearing a 5' biotin tag is immobilized on the surface of streptavidin-coated magnetic beads, and ligated product is detected via a 3' digoxigenin tag recognized by monoclonal antibody-alkaline phosphatase conjugate. Enzymatic conversion of napht-1-yl phosphate to napht-1-ol enables sensitive detection of the voltammetric signal on a pyrolytic graphite electrode. The technique was tested under optimal conditions and various situations limiting or precluding the ligation reaction (such as DNA substrates lacking 5'-phosphate or containing a base mismatch at the nick junction, or application of incompatible cofactor), and utilized for the analysis of the nick-joining activity of a range of recombinant Escherichia coli DNA ligase constructs. The novel technique provides a fast, versatile, specific, and sensitive electrochemical assay of DNA ligase activity.

• MeSH
• DNA Ligases chemistry   MeSH
• DNA chemistry   MeSH
• Electrochemical Techniques instrumentation   methods   MeSH
• Enzyme Assays instrumentation   methods   MeSH
• Enzymes, Immobilized chemistry   MeSH
• Escherichia coli chemistry   enzymology   MeSH
• Magnetics MeSH
• Escherichia coli Proteins chemistry   MeSH
• Publication type
• Journal Article MeSH
• Evaluation Study MeSH
• Research Support, Non-U.S. Gov't MeSH

Specific allergen immunotherapy is frequently associated with adverse reactions. Several strategies are being developed to reduce the allergenicity while maintaining the therapeutic benefits. Peptide immunotherapy is one such approach. Methods for the simple and rapid identification of immunogenic epitopes of allergens (i.e. allergenic epitopes) are ongoing and could potentially lead to peptide-based vaccines. An epitope extraction technique, based on biofunctionalized magnetic microspheres self-organized under a magnetic field in a channel of a simple microfluidic device fabricated from polydimethylsiloxane, was applied in the isolation and identification of prospective allergenic epitopes. Similarly to chromatographic column separations, the easily replaceable plug of self-organized beads in the channel benefits especially from an even larger surface-to-volume ratio and an enhanced interaction of the surfaces with passing samples. Ovalbumin, the major protein of egg white and a typical representative of food allergens, was selected as the model molecule. Highly resistant ovalbumin was at first efficiently digested by a magnetic proteolytic reactor with trypsin treated with l-1-tosylamido-2-phenylethyl chloromethyl ketone and the second step, i.e. capture of allergenic epitopes from the mixture of peptides, was performed by a magnetic immunoaffinity carrier with orientedly immobilized rabbit anti-ovalbumin IgG molecules. Captured peptides were released with 0.05% trifluoroacetic acid. The elution fractions were analyzed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. The peptide fragment of ovalbumin HIATNAVLFFGR (m/z: 1345.75, position: 371-382) was identified as a relevant allergenic epitope in this way. Such a microfluidic magnetic force-based epitope extraction technique applied in the epitope mapping of ovalbumin has the potential to be a significant step towards developing safe and cost-effective epitope-based vaccines.

• MeSH
• Allergens chemistry   immunology   MeSH
• Epitopes analysis   MeSH
• Financing, Organized MeSH
• Mass Spectrometry MeSH
• Immunomagnetic Separation methods   MeSH
• Epitope Mapping methods   MeSH
• Microfluidic Analytical Techniques methods   MeSH
• Microspheres MeSH
• Ovalbumin chemistry   immunology   MeSH
• Food Hypersensitivity MeSH
• Vaccines MeSH

Early-stage diagnosis of prostatic carcinoma is essential for successful treatment and, thus, significant prognosis improvement. In laboratory practice, the standard non-invasive diagnostic approach is the immunochemical detection of the associated biomarker, prostate-specific antigen (PSA). Ultrasensitive detection of PSA is essential for both diagnostic and recurrence monitoring purposes. To achieve exceptional sensitivity, we have developed a microfluidic device with a flow-through cell for single-molecule analysis using photon-upconversion nanoparticles (UCNPs) as a detection label. For this purpose, magnetic microparticles (MBs) were first optimized for the capture and preconcentration of PSA and then used to implement a bead-based upconversion-linked immunoassay (ULISA) in the microfluidic device. The digital readout based on counting single nanoparticle-labeled PSA molecules on MBs enabled a detection limit of 1.04 pg mL-1 (36 fM) in 50% fetal bovine serum, which is an 11-fold improvement over the respective analog MB-based ULISA. The microfluidic technique conferred several other advantages, such as easy implementation and the potential for achieving high-throughput analysis. Finally, it was proven that the microfluidic setup is suitable for clinical sample analysis, showing a good correlation with a reference electrochemiluminescence assay (recovery rates between 97% and 105%).

• MeSH
• Immunoassay instrumentation   methods   MeSH
• Humans MeSH
• Limit of Detection MeSH
• Microfluidic Analytical Techniques instrumentation   MeSH
• Prostatic Neoplasms diagnosis   blood   MeSH
• Nanoparticles chemistry   MeSH
• Prostate-Specific Antigen * analysis   blood   MeSH
• Check Tag
• Humans MeSH
• Male MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH

Magnetic bead cellulose was prepared by a suspension method from the mixture of viscose and magnetite using thermal sol-gel transition and regeneration of cellulose. The prepared magnetic particles after their activation with divinyl sulfone were shown to be suitable magnetic carrier for immobilization of α-chymotrypsin and for its application in proteomic studies. The specific activity of the immobilized proteinase was high; its activity did not change in the course of storage. The following properties of the immobilized proteinase were compared with those of the soluble enzyme: pH and temperature dependence of the activity, self-cleavage activity, and possibility of repeated use. α-Chymotrypsin immobilized to magnetic bead cellulose was used for the proteolytic digestion of porcine pepsin A and human gastric juice and a possibility of direct use of enzyme reaction products for matrix-assisted laser desorption/ionization time of flight mass spectrometry analysis was shown.

• MeSH
• Cellulose chemistry   MeSH
• Chymotrypsin chemistry   metabolism   MeSH
• Enzymes, Immobilized chemistry   metabolism   MeSH
• Humans MeSH
• Magnets chemistry   MeSH
• Microspheres * MeSH
• Molecular Sequence Data MeSH
• Pepsin A chemistry   metabolism   MeSH
• Proteolysis MeSH
• Solubility MeSH
• Amino Acid Sequence MeSH
• Cattle MeSH
• Sulfones chemistry   MeSH
• Gastric Juice enzymology   MeSH
• Animals MeSH
• Check Tag
• Humans MeSH
• Cattle MeSH
• Animals MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH

Magnetic harvesting of microalgal biomass provides an attractive alternative to conventional methods. The approach to this issue has so far been pragmatic, focused mainly on finding cheap magnetic agents in combination with harvestable microalgae species. The aim of this work was to study experimentally and theoretically the mechanisms leading to cell-magnetic agent attachment/detachment using real experiments and predictions made by colloidal adhesion (XDLVO) model. Two types of well defined magnetic beads (MBs) carrying ion exchange functional groups (DEAE - diethylaminoethyl and PEI - polyethylenimine) were studied in connection with microalgae (Chlorella vulgaris). Optimal harvesting efficiencies (>90%) were found for DEAE and PEI MBs, while efficient detachment was achieved only for DEAE MBs (>90%). These findings were in accordance with the predictions by XDLVO model. Simultaneously there was found a discrepancy between the XDLVO prediction and the poor detachment of PEI MBs from microalgal surface. This can be ascribed to an additional interaction (probably covalent bonds) between PEI and algal surface, which the XDLVO model is unable to capture given by its non-covalent nature.

• MeSH
• Models, Biological MeSH
• Biomass MeSH
• Cell Adhesion MeSH
• Chlorella vulgaris isolation & purification   physiology   MeSH
• Ethanolamines chemistry   MeSH
• Ion Exchange MeSH
• Colloids MeSH
• Magnetic Phenomena MeSH
• Magnetite Nanoparticles chemistry   MeSH
• Microalgae isolation & purification   physiology   MeSH
• Polyethyleneimine chemistry   MeSH
• Surface Properties MeSH
• Industrial Microbiology methods   MeSH
• Fresh Water microbiology   MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH

Investigation of protein glycosylation is an important area in biomarker discovery and biopharmaceutical research. Alterations in protein N-glycosylation can be an indication of changes in pathological conditions in the medical field or production parameters of biotherapeutics. Rapid development of these disciplines calls for fast, high-throughput, and reproducible methods to analyze protein N-glycosylation. Currently used methods require either long deglycosylation times or large excess of enzymes. In this paper, we report on the use of PNGase F immobilization onto the surface of magnetic microparticles and their use in rapid and efficient removal of N-glycans from glycoproteins. The use of immobilized PNGase F also allowed reusability of the enzyme-coated beads as the magnetic microparticles can be readily partitioned from the sample by a magnet after each deglycosylation reaction. The efficiency and activity of the PNGase F coated magnetic beads was compared with in-solution enzyme reactions using standard glycoproteins possessing the major N-glycan types of neutral, high mannose, and highly sialylated carbohydrates. The PNGase F coated magnetic beads offered comparable deglycosylation level to the conventional in-solution based method in 10-min reaction times for the model glycoproteins of immunoglobulin G (mostly neutral carbohydrates), ribonuclease B (high mannose type sugars), and fetuin (highly sialylated oligosaccharides) with the special features of easy removal of the enzyme from the reaction mixture and reusability.

• MeSH
• Electrophoresis MeSH
• Enzymes, Immobilized metabolism   MeSH
• Peptide-N4-(N-acetyl-beta-glucosaminyl) Asparagine Amidase metabolism   MeSH
• Glycoproteins chemistry   metabolism   MeSH
• Glycosylation MeSH
• Immunoglobulin G chemistry   metabolism   MeSH
• Microspheres * MeSH
• Oligosaccharides metabolism   MeSH
• Polysaccharides metabolism   MeSH
• Ribonucleases chemistry   metabolism   MeSH
• Publication type
• Journal Article MeSH