Biokatalitikus aktivitás mérésére alkalmas mikrofabrikált elektrokémiai bioszenzorok fejlesztése és vizsgálata = Development and study of microfabricated electrochemical biosensors for biocatalyst assay

1. Miniatűr amperometriás mérőcellákat fejlesztettünk ki enzimaktivitás mérésére 1-10 micro l térfogatú mintákból mikrofabrikációs technológiák alkalmazásával. Az alapérzékelők szelektív válaszának biztosítására elektrokatalizátorokat, többrétegű polielektrolit, illetve elektropolimerizációval készült filmeket vizsgáltunk. Bizonyítottuk a kifejlesztett bioszenzorok alkalmasságát egyes oxidáz és hidroláz enzimek, illetve enzimszubsztrátok közvetlen meghatározására. 2. Fotolitográfia, mikrokontakt nyomtatás és különböző immobilizációs eljárások alkalmazásával mikroszkopikus méretű nukleinsav és protein mintázatokat alakítottunk ki aranyfelületeken. Módszert dolgoztunk felületen immobilizált glükóz-oxidáz enzim rétegek aktivitásának kvantitatív meghatározására pásztázó elektrokémiai mikroszkópia és digitális szimuláció alkalmazásával. A pásztázó elektrokémiai mikroszkópiát világszinten először alkalmaztuk sikeresen DNS szálak hibridizálódásának enzimaktivitás mérésen alapuló detektálására. 3. Új detektálási elveket dolgoztunk ki nukleinsavak hibridizációja és immunreakciók nyomonkövetésére felületi plazmon rezonanciás mérőrendszer és kémiailag módosított arany nanocsövek alkalmazásával. 4. Spektroelektrokémiai mikroszkópiás módszert dolgoztunk ki anyagtranszport kontrollált ionszelektív membránok vizsgálatára amellyel a membránkomponensek elektromos tér, illetve koncentrációgradiens indukált transzportja valósidőben nyomonkövethető. Új eljárásokat vezettünk be nanomólos kimutatási határú ionszelektív elektródok előállítására. | 1. Microfabricated amperometric microcells were developed for enzyme and enzyme substrate assays in microliter volume samples. Different selectivity enhancing layers based on electrocatalysts, polyelectrolyte multilayers and electropolymerized films were investigated. The applicability of the miniaturized biosensors for the assay of certain oxidase and hydrolase enzymes has been proved. 2. Photolithography, microcontact printing and different immobilization strategies were used to fabricate protein and nucleic acid micropatterns on gold surfaces. A new method was developed for quantification of the activity of surface confined enzymes based on 3D digital simulation in combination with scanning electrochemical microscopy. Scanning electrochemical microscopy was used successfully for the detection of nucleic acid hybridization events in conjunction with enzyme labeling. 3. New strategies were developed for the detection of affinity type biomolecular interactions based on surface plasmon resonance imaging and chemically modified nanotubules. It was shown that the potentiometric monitoring of an indicator ion such as Ca2+, whose zero-current flux through chemically modified nanochannels is altered by biorecognition events provides a sensitive label-free biosensing approach for protein and nucleic acid assays. 4. Spectroelectrochemical microscopy has been implemented as a novel method for multi-spectral imaging of ion transport processes in neutral carrier-based cation-selective membranes. New approaches for the fabrication of ion-selective sensors for the ultra trace analysis of calcium and lead ions were developed

Szintetikus receptor alapú kémiai szenzorok fejlesztése, tanulmányozása = Development and mechanistic study of chemical sensors based on synthetic receptors

Új szintetikus receptor molekulákat, elsősorban koronaétereket és kalixaréneket terveztünk és az előállított vegyületeket fizikai-kémiai módszerekkel jellemeztük kémiai szenzorok előállításához. A receptor molekulá-kat jelátvivő egységgel egy eszközben integrálva szenzorokat alakítottunk ki élettani, környezetvédelmi és élelmiszer minőségbiztosítás szempontjából fontos ionok meghatározására. Különböző eljárást dolgoztunk ki anyagtranszport kontrollált ionszelektív elektródok előállítására a szenzor paraméterek javítása céljából. Elsőként publikáltuk az ionofor-arany nanorészecske konjugátumok alkalmazását, mint új lehetőséget ionoforok ionszelektív membránban való rögzítésére. Az originális ötlet alapján ezüst szenzort fejlesztettünk ki, mely nanomólos kimutatási határral jelzi az ezüstionokat és megmutattuk az ilyen típusú érzékelők nyomanalitikai alkalmazhatóságát. Új elektród konstrukciót és eljárást javasoltunk robusztus, szilárd belső elvezetésű ionszelektív elektródok előállítására, mely pásztátó elektrokémiai mikroszkóphoz adaptálva ion-koncentrációk térben és időben való analízisét teszi lehetővé. Fluoreszcens iminodiacatamid tipusú receptor felhasználásával a cinkionok nanomólos tartományban való mérésére optikai cink ionszelektív szenzort, élelmiszerek nehézfém szennyezőinek szimultán meghatározására kémiailag módosított voltammetriás szenzort, míg mikroorganizmus és növényvédőszer szennyezők gyors meghatározására bioszenzorokat fejlesztettünk ki. | Novel synthetic receptors, primarily crown ethers and calixarenes have been synthesized and characterized for chemical sensors. By coupling the original sensormolecules to different signal transduction units new chemical sensors were fabricated for the selective determination of ions important in physiology, environmental protection and food quality control. Different approaches have been elaborated for the fabrication of mass transport controlled ion-selective sensors with improved analytical parameters. For the first time we have reported on the application of ionophore-gold nanoparticle conjugates as a new concept in confining ionophores to ion-selective membranes using inert nanoparticle carriers. Based on this new concept silver selective sensors were fabricated and the applicability of this type of sensors for trace analysis has been demonstrated. Potentiometric miroelectrodes of robust construction, adaptable to Scanning Electrochemical Microscope have been suggested for analysis in biological fluids. For the detection of zinc in the nanomolar concentration range optical zinc ion-selective sensor, while for the simultaneous detection of heavy metals at trace level in foods receptor modified voltammetric sensors, and for the analysis of microorganism and pesticides biosensors were developed

Szérumbiomarkerek akut lumbalis-lumbosacralis fájdalomban

Inflammation contributes to the pathogenesis of low back pain and sciatica. Growing evidence suggests that elevated levels of some inflammatory biomarkers are associated with these conditions. Much of the research evaluating the association between pro- and anti-inflammatory cytokines, chemokines, other regulatory molecules, and low back pain and sciatica, focused on patients with chronic low back pain, while fewer studies addressed the issue of detectable biomarkers in the acute phase. Previous studies suggest that pro-inflammatory cytokines such as TNF-alpha, IL-6, and IL-8 and anti-inflammatory IL-4 and IL-10 play an important role in the inflammatory response following intervertebral disc herniation. According to the approach of personalized medicine it is important to identify subsets of patients within the acute patient group regarding etiology, prognosis and treatment. In addition, if we can identify subgroups based on levels of pro-inflammatory biomarkers, where inflammation may be the leading cause of pain, we assume that this subgroup would likely be effectively treated with anti-inflammatory medication. The efficacy of TNF-alpha inhibitors and IL-6 inhibitors in treating low back pain and sciatica has already been tested in clinical trials, but further studies are required. Overall, identification of circulating biomarkers of acute low back pain and sciatica may assist in refining personalized diagnosis and treatment. Further research is needed to evaluate the role of inflammation in acute low back pain and sciatica, to identify what methods are appropriate for evaluation in clinical practice, and whether there are biomarkers of prognostic value in these patients

The effects of the post-reunification reforms on the German economy

A dolgozatom témájául Németország gazdasági vizsgálatát választottam, ezen belül pedig azt, hogy az AGENDA 2010 elnevezésű reformok milyen szerepet töltöttek be abban, hogy a 2000-es évek hanyatló gazdasága után Németország napjainkra Európa vezető gazdasági hatalma lett.Németország azért volt érdekes számomra, mert a 90-es évek elején egy olyan gazdasági helyzettel találta szembe magát, aminek megoldására nem volt eddig recept, senki semmilyen formában nem írta azt le, dolgozta ki, hogyan tud egy erős gazdasággal rendelkező ország integrálni és saját maga szintjére felzárkóztatni egy sokkal szerényebb képességű országrészt.A felzárkóztatást magas transzferekkel próbálták megoldani, ami az első néhány évben hozott is eredményeket, de a 90-es évek közepétől a fejlődés megállt.A 2000-es évek elejét gazdasági stagnálás, magas munkanélküliség, jelentős államadósság jellemezte.2003-ban Gerhard Schröder bejelentette az Agenda 2010 reformcsomagot, aminek egyik legfontosabb eleme a munkaerő-piaci reformok voltak.A reformok bejelentése után nem sokkal egy jelentős változás állt be a munkaerőpiacon és szignifikánsan csökkent a munkanélküliség.Dolgozatomban azt vizsgáltam, hogy milyen szerepet játszottak ebben a reformok, a reformoknak voltak-e egyéb hatásai, valamint milyen egyéb tényezők voltak még hatással a pozitív munkaerő-piaci változásokra.egyetemiGazdálkodásiK

A szülési fájdalom mérésével szerzett tapasztalataink

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Simple, single step potential difference measurement for the determination of the ultimate detection limit of ion selective electrodes

A single step measurement is proposed for evaluating the ultimate detection limit of ion selective electrodes. The essence of the method is the calculation of the detection limit from a potential difference measured across a membrane in equilibrium with deionized water when it is challenged with a relatively concentrated primary or interfering ion solution on one of its sides. It is aimed for fast screening of novel ionophore candidates and for reexamining existing ones to sort out those which are adequate for selective, subnanomolar analysis. The feasibility and the practical usefulness of the method is demonstrated upon the characterization potassium ion-selective electrodes with novel, and well-known ionophores. The proposed potential difference-based method is coupled to subsequent exponential dilutions for the determination the response slopes, selectivity coefficients and detection limits of the tested electrodes. This combination of electrode testing protocols provides full characterization of the studied electrodes and a back to back comparison of the indirectly calculated and directly measured detection limits. The calibration of the electrodes in dilute solutions revealed the superior dynamic response properties of the electrodes with the covalently anchored ionophore in submicromolar concentrations. © 2006 Wiley-VCH Verlag GmbH & Co. KGaA

How to assess the limits of ion-selective electrodes: Method for the determination of the ultimate span, response range, and selectivity coefficients of neutral carrier-based cation selective electrodes

The span and range of an ion-selective electrode (ISE) has been identified by IUPAC as a potential or activity difference between the upper and lower detection limits of the electrode. Once the span is known, the ultimately attainable detection limit of the ISE can be calculated using its theoretical response slope. In this paper, we propose an original method for the determination of the ultimate span and response range of ISEs. The simple measurement of span is recommended to aid the fast screening of novel ionophores and help to focus optimization processes to the most promising candidates. The measurement of span is combined with a generally applicable procedure for the determination of the three seminal parameters of ISEs: the response slope, the ultimate selectivity coefficients, and detection limit. In the proposed procedure, following the span measurement, two subsequent exponential dilution experiments are completed in which the responses of the electrode for the primary and the interfering ions are tested using a solution of a discriminated ion and deionized water as diluting electrolytes in consecution. The advantages and the practical usefulness of the proposed methods and procedures are demonstrated through the evaluation of the performance characteristics of novel and well-characterized ionophore-based potassium and calcium sensors. © 2006 American Chemical Society

Amperometric microcells for alkaline phosphatase assay

To develop simple electrochemical immunoassays, a screen printed amperometric microcell with graphite working and Ag/AgCl reference electrodes was tested for the determination of alkaline phosphatase enzyme (ALP) and anti-humanIgG conjugated ALP (α-hIgG-ALP) activity in 5-10 μl samples. To ensure reproducible, steady state conditions, the working electrode surface was coated with mass-transport controlling hydrogel layer. The kinetic response curves of the hydrogel coated electrodes were linear. In addition, the hydrogel layer reduced the nonspecific adsorption of the α-hIgG-ALP conjugate on the working electrode surface. The measurements were made in the range of 2 ÷ 4000 mU ml-1enzyme activities using ascorbic acid 2-phosphate (AAP) as the enzyme substrate. AAP is commercially available, non-toxic and has excellent stability. The sensitivity of the determinations was about 71% of the sensitivity which could be achieved using p-aminophenylphosphate (PAPP), a not easily accessible and unstable enzyme substrate. The experimentally determined kinetic parameters of the ALP enzyme catalyzed reactions were the same with the bare and hydrogel layer coated electrodes

A nagy felbontasú ideg-ultrahangvizsgálatok jelentősége a perifériás idegek betegségeinek diagnosztikájában [The significance of high-resolution ultrasonography in the diagnosis of peripheral nerve disorders]

High resolution ultrasonography is an emerging technique for the investigation of peripheral nerves and is increasingly used worldwide in the diagnosis of peripheral nerve disorders, however, until now it is not widespread in Hungary. According to the literature this method is especially useful in entrapment neuropathies, traumatic peripheral nerve injuries, tumors of the peripheral nerves and sonographically guided interventions. Ultrasonography allows precise morphological analysis and quantitative measurements of the nerves providing useful complementary information to electrodiagnostic data. In entrapment neuropathies ultrasound shows nerve swelling mainly proximal to the sites of compression and a focal change of echotexture. On longitudinal scan, an abrupt caliber change and spindle-like swelling of the compressed nerve segment can be seen. Evaluation of the anatomical background and visualisation of the postoperative and posttraumatic changes provide useful information for planning of the therapy. Ultrasound may be of significant help in localizing the pathological nerve segment when it is at an electrophysiologically inaccessible site or when substantial secondary axonal loss precludes precise electrophysiological localization and it might even show pathological changes when nerve conduction studies are normal. Contrary to electrophysiological investigation ultrasonography might discover neurotmesis in the akute phase of traumatic nerve injuries indicating the necessity of surgical intervention. We provide a summary of the main indications and further application areas of this method

Impaired cerebrovascular reactivity correlates with reduced retinal vessel density in patients with carotid artery stenosis: Cross-sectional, single center study.

BackgroundThe cerebral and retinal circulation systems are developmentally, anatomically, and physiologically interconnected. Thus, we hypothesized that hypoperfusion due to atherosclerotic stenosis of the internal carotid artery (ICA) can result in disturbances of both cerebral and retinal microcirculations. We aimed to characterize parameters indicating cerebrovascular reactivity (CVR) and retinal microvascular density in patients with ICA stenosis, and assess if there is correlation between them.MethodsIn this cross-sectional study the middle cerebral artery (MCA) blood flow velocity was measured by transcranial Doppler (TCD) and, simultaneously, continuous non-invasive arterial blood pressure measurement was performed on the radial artery by applanation tonometry. CVR was assessed based on the response to the common carotid artery compression (CCC) test. The transient hyperemic response ratio (THRR) and cerebral arterial resistance transient hyperemic response ratio (CAR-THRR) were calculated. Optical coherence tomography angiography (OCTA) was used to determine vessel density (VD) on the papilla whole image for all (VDP-WIall) and for small vessels (VDP-WIsmall). The same was done in the peripapillary region: all (VDPPall), and small (VDPPsmall) vessels. The VD of superficial (VDMspf) and deep (VDMdeep) macula was also determined. Significance was accepted when pResultsTwenty-four ICA stenotic patients were evaluated. Both CVR and retinal VD were characterized. There was a significant, negative correlation between CAR-THRR (median = -0.40) and VDPPsmall vessels (median = 52%), as well as between VDPPall vessels (median = 58%), and similar correlation between CAR-THRR and VDP-WIsmall (median = 49.5%) and between VDP-WIall (median = 55%).ConclusionThe significant correlation between impaired cerebrovascular reactivity and retinal vessel density in patients with ICA stenosis suggests a common mechanism of action. We propose that the combined use of these diagnostic tools (TCD and OCTA) helps to better identify patients with increased ischemic or other cerebrovascular risks