Testing the hemocompatibility of medical devices after their interaction with blood entails the need to evaluate the activation of blood elements and the degree of their coagulation and adhesion to the device surface. One possible way to achieve this is to use scanning electron microscopy (SEM). The aim was to develop a novel SEM-based method to assess the thrombogenic potential of medical devices and their adhesiveness to blood cells. As a part of this task, also find a convenient procedure of efficient and non-destructive sample fixation for SEM while reducing the use of highly toxic substances and shortening the fixation time. A polymeric surgical mesh was exposed to blood so that blood elements adhered to its surface. Such prepared samples were then chemically fixed for a subsequent SEM measurement; a number of fixation procedures were tested to find the optimal one. The fixation results were evaluated from SEM images, and the degree of blood elements' adhesion was determined from the images using ImageJ software. The best fixation was achieved with the May-Grünwald solution, which is less toxic than chemicals traditionally used. Moreover, manipulation with highly toxic osmium tetroxide can be avoided in the proposed procedure. A convenient methodology for SEM image analysis has been developed too, enabling to quantitatively evaluate the interaction of blood with the surfaces of various medical devices. Our method replaces the subjective assessment of surface coverage with a better-defined procedure, thus offering more precise and reliable results.
- MeSH
- histologické techniky * MeSH
- mikroskopie elektronová rastrovací MeSH
- oxid osmičelý * MeSH
- Publikační typ
- časopisecké články MeSH
Characterization of brain infarct lesions in rodent models of stroke is crucial to assess stroke pathophysiology and therapy outcome. Until recently, the analysis of brain lesions was performed using two techniques: (1) histological methods, such as TTC (Triphenyltetrazolium chloride), a time-consuming and inaccurate process; or (2) MRI imaging, a faster, 3D imaging method, that comes at a high cost. In the last decade, high-resolution micro-CT for 3D sample analysis turned into a simple, fast, and cheaper solution. Here, we successfully describe the application of brain contrasting agents (Osmium tetroxide and inorganic iodine) for high-resolution micro-CT imaging for fine location and quantification of ischemic lesion and edema in mouse preclinical stroke models. We used the intraluminal transient MCAO (Middle Cerebral Artery Occlusion) mouse stroke model to identify and quantify ischemic lesion and edema, and segment core and penumbra regions at different time points after ischemia, by manual and automatic methods. In the transient-ischemic-attack (TIA) mouse model, we can quantify striatal myelinated fibers degeneration. Of note, whole brain 3D reconstructions allow brain atlas co-registration, to identify the affected brain areas, and correlate them with functional impairment. This methodology proves to be a breakthrough in the field, by providing a precise and detailed assessment of stroke outcomes in preclinical animal studies.
- MeSH
- cévní mozková příhoda * diagnostické zobrazování patologie MeSH
- infarkt arteria cerebri media diagnostické zobrazování patologie MeSH
- jod * MeSH
- modely nemocí na zvířatech MeSH
- myši MeSH
- oxid osmičelý MeSH
- rentgenová mikrotomografie MeSH
- zvířata MeSH
- Check Tag
- myši MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Osmium tetroxide is a strong oxidizing agent used in electron microscopy. Eye exposure may cause severe burns, and after inhalation or ingestion damage to the respiratory or gastrointestinal tract occurs. Exposure to osmium and its compounds is extremely rare. We present a case of a 32-year-old female stained by 9 mL of 2% osmium tetroxide in acetone during an accident in the laboratory, with rare dermal and ocular findings. Due to lack of data in toxicological databases and the absence of antidote, the therapy was symptomatic. Osmium was detected in serum 19 hours later (0.22 μg/L) and in urine during the 15-hour collection (three samples-7.05, 1.65 and 8.45 μg/L). In blood serum on admission, after 1 and 2 days after exposure, the levels of iron (28.2, 39.8 and 50.5 μmol/L; reference range 5.8-34.5 μmol/L) and transferrin receptor/ferritine were elevated. To our knowledge, this is the first paper documenting a significant absorption from the skin and potentially from the eye conjunctiva, based on serum and urine analysis. The relationship between increased iron in blood and exposure has not been described yet, and the mechanism remains unknown. The patient is being followed up for the unknown long-term effects.
- MeSH
- dospělí MeSH
- kůže účinky léků MeSH
- lidé MeSH
- oči účinky léků MeSH
- oxid osmičelý otrava MeSH
- Check Tag
- dospělí MeSH
- lidé MeSH
- ženské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
- kazuistiky MeSH
This review is focused on the reaction of 1,2-diols with ligand complexes of six-valent osmium [Os(VI)L] (where L is a nitrogenous ligand) and possibilities of electrochemical analysis of yielded products. A number of biologically important molecules, such as mono-, oligo- and polysaccharides, RNA and glycoproteins, belong to compounds containing 1,2-diol in their structure. These compounds react with Os(VI)L yielding relatively stable ligand osmate esters which are electrochemically active and suitable to the electrochemical analysis. The ligand osmate esters give redox peaks at the mercury and carbon electrodes. The redox peaks are due to the electrochemical reduction or oxidation of osmium atoms. The osmate esters with some ligands give catalytic peaks at the mercury electrodes. The catalytic peak is due to the catalytic hydrogen evolution and is very sensitive. With the catalytic peak it is possible to measure picomolar concentrations in some cases. We have used reactions of Os(VI)L for the analysis of glycans and glycoproteins in relation to their great importance in biomedicine.
The review deals with osmium tetroxide, a very toxic volatile substance. It can be misused as a chemical weapon intoxicating by inhalation in closed space with limited air circulation (airports, shopping centres). In contrast, osmium tetroxide is very important compound in analytical chemistry especially in electron microscopy and DNA labelling in biophysical chemistry. Some analytical techniques for its detection are discussed with an emphasis on voltammetric methods.
[New chemical terrorism weapon - osmium tetroxide]
- MeSH
- chemický terorismus MeSH
- diagnostické techniky a postupy využití MeSH
- kožní manifestace MeSH
- lidé MeSH
- oční symptomy MeSH
- otrava diagnóza prevence a kontrola terapie MeSH
- oxid osmičelý otrava škodlivé účinky MeSH
- příznaky a symptomy ústrojí dýchacího MeSH
- příznaky a symptomy ústrojí trávicího MeSH
- příznaky a symptomy MeSH
- první pomoc metody využití MeSH
- Check Tag
- lidé MeSH
A complex of osmium tetroxide with 2,2'-bipyridine (Os,bipy) has been applied as a chemical probe of DNA structure as well as an electroactive DNA label. The Os,bipy has been known to form covalent adducts with pyrimidine DNA bases. Besides the pyrimidines, electrochemically active covalent adducts with Os,bipy are formed also by tryptophan (W) residues in peptides and proteins. In this paper we show that Os,bipy-treated proteins possessing W residues (such as avidin, streptavidin, or lysozyme) yield at the pyrolytic graphite electrode (PGE) a specific signal (peak alphaW) the potential of which differs from the potentials of signals produced by free Os,bipy or by Os,bipy-modified DNA. No such signal is observed with proteins lacking W (such as ribonuclease A or alpha-synuclein). Subpicomole amounts of W-containing proteins modified with Os,bipy can easily be detected using adsorptive transfer stripping voltammetry with the PGE. Binding of biotin to avidin interferes with Os,bipy modification of the protein, in agreement with the location of W residues within the biotin-binding site of avidin. These Ws are accessible for modification in the absence of biotin but hidden (protected from modification) in the avidin-biotin complex. The Os,bipy-modified avidin is unable to bind biotin, and its quarternary structure is disrupted. Analogous effects were observed with another biotin-binding protein, streptavidin. Our results demonstrate that modification of proteins with Os,bipy under conditions close to physiological, followed by a simple electrochemical analysis, can be applied in the microanalysis of protein structure and interactions.
- MeSH
- 2,2'-dipyridyl chemie MeSH
- avidin chemie MeSH
- biotin chemie MeSH
- elektrochemie MeSH
- elektrody MeSH
- elektrony MeSH
- financování organizované MeSH
- molekulární struktura MeSH
- oxid osmičelý analýza chemie MeSH
- proteiny analýza chemie MeSH
- reagencia zkříženě vázaná chemie MeSH
- tryptofan analýza chemie MeSH
- uhlík chemie MeSH
Labeling of oligonucleotide reporter probes (RP) with electroactive markers has frequently been utilized in electrochemical detection of DNA hybridization. Osmium tetroxide complexes with tertiary amines (Os,L) bind covalently to pyrimidine (predominantly thymine) bases in DNA, forming stable, electrochemically active adducts. We propose a technique of electrochemical "multicolor" DNA coding based on RP labeling with Os,L markers involving different nitrogenous ligands (such as 2,2' -bipyridine, 1,10-phenanthroline derivatives or N,N,N',N'-tetramethylethylenediamine). At carbon electrodes the Os,L-labeled RPs produce specific signals, with the potentials of these differing depending on the ligand type. When using Os,L markers providing sufficiently large differences in their peak potentials, parallel analysis of multiple target DNA sequences can easily be performed via DNA hybridization at magnetic beads followed by voltammetric detection at carbon electrodes. Os,L labeling of oligonucleotide probes comprising a segment complementary to target DNA and an oligo(T) tail (to be modified with the osmium complex) does not require any organic chemistry facilities and can be achieved in any molecular biological laboratory. We also for the first time show that this technology can be used for labeling of oligonucleotide probes hybridizing with target DNAs that contain both purine and pyrimidine bases.
Hydrogen peroxide and nicotinamide adenine dinucleotide (NADH) may be determined amperometrically using screen-printed electrodes chemically modified with iron(III) hexacyanoosmate(II) (Osmium purple) in flow injection analysis (FIA). The determination is based on the exploitation of catalytic currents resulting from the oxidation/reduction of the modifier. The performance of the sensor was characterized and optimized by controlling several operational parameters (applied potential, pH and flow rate of the phosphate buffer). Comparison has been made with analogous complexes of ruthenium (Ruthenium purple) and iron (Prussian blue). Taking into account the sensitivity and stability of corresponding sensors, the best results were obtained with the use of Osmium purple. The sensor exhibited a linear increase of the amperometric signal with the concentration of hydrogen peroxide in the range of 0.1-100 mg L(-1) with a detection limit (evaluated as 3sigma) of 0.024 mg L(-1) with a R.S.D. 1.5% for 10 mg L(-1) H2O2 under optimized flow rate of 0.4 mL min(-1) in 0.1M phosphate buffer carrier (pH 6) and a working potential of +0.15 V versus Ag/AgCl. Afterwards, a biological recognition element--either glucose oxidase or ethanol dehydrogenase--was incorporated to achieve a sensor facilitating the determination of glucose or ethanol, respectively. The glucose sensor gave linearity between current and concentration in the range from 1 to 250 mg L(-1) with a R.S.D. 2.4% for 100 mg L(-1) glucose, detection limit 0.02 mg L(-1) (3sigma) and retained its original activity after 3 weeks when stored at 6 degrees C. Optimal parameters in the determination of ethanol were selected as: applied potential +0.45 V versus Ag/AgCl, flow rate 0.2 mL min(-1) in 0.1 M phosphate buffer carrier (pH 7). Different structural designs of the ethanol sensor were tested and linearity obtained was up to 1000 mg L(-1) with a maximum R.S.D. of 5.1%. Applications in food analysis were also examined.
- MeSH
- alkoholdehydrogenasa analýza MeSH
- alkoholické nápoje analýza MeSH
- analýza potravin metody MeSH
- biosenzitivní techniky metody MeSH
- elektrochemie metody MeSH
- enzymy imobilizované MeSH
- ethanol analýza MeSH
- ferrokyanidy chemie MeSH
- financování organizované MeSH
- glukosa analýza MeSH
- glukosaoxidasa analýza MeSH
- katalýza MeSH
- NAD chemie MeSH
- oxid osmičelý chemie MeSH
- peroxid vodíku chemie MeSH
- sloučeniny ruthenia chemie MeSH
- železité sloučeniny chemie MeSH
- Publikační typ
- srovnávací studie MeSH
