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At least 595 records · Page 33Linked to original sources
PubMed2005

Acetylcholinesterase sensor based on screen-printed carbon electrode modified with prussian blue.

Acetylcholinesterase (ChE) sensor based on Prussian blue (PB) modified electrode was developed and tested for the detection of organophosphorus and carbamic pesticides. The signal of the sensor was generated in PB mediated oxidation of thiocholine recorded at +200 mv in DC mode. ChE from electric eel was immobilized by cross-linking with glutaraldehyde in the presence of bovine serum albumin (BSA) on the surface of screen-printed carbon electrode covered with PB and Nafion. The content of the surface layer (specific enzyme activity, Nafion and BSA amounts) was optimized to establish high and reliable response toward the substrate and ChE inhibitors. The ChE/PB sensor makes it possible to detect Aldicarb, Paraoxon and Parathion-Methyl with limits of detection 30, 10 and 5 ppb, respectively (incubation 10 min). The feasibility of practical application of the ChE/PB sensor developed for the monitoring of degradation of the pesticides in wine fermentation was shown. To diminish matrix interferences, the electrolysis of the grape juice with Al anode and evaporation of ethanol were suggested, however the procedures decrease the sensitivity of pesticide detection and stability of the sample tested.

Acetylcholinesterase↗
PubMed2005

Electrochemical study on screen-printed carbon electrodes with modification by iron nanoparticles in Fe(CN)(6) (4-/3-) redox system.

The remarkable enhancement of electron transfer on screen-printed carbon electrodes (SPCEs) with modification by iron nanoparticles (Fe(nano)), coupled with Fe(CN)(6) (4-/3-) redox species, was characterized with an increase of electroactive area (A (ea)) at electrode surface together with a decrease of heterogeneous electron transfer rate constant (k degrees ) in the system. Hence, Fe(nano)-Fe(CN)(6) (3-) SPCEs with deposition of glucose oxidase (GOD) demonstrated a higher sensitivity to various glucose concentrations than Fe(CN)(6) (3-)/GOD-deposited SPCEs. In addition, an inhibited diffusion current from cyclic voltammograms was also observed with an increase in redox concentration and complicated the estimation of A (ea). Further analysis by the electrochemical impedance method, it was shown that this effect might be resulted from the electrode surface blocking by the products of activated complex decomposition.

Journal Article↗
PubMed2005

Development of cysteine-modified screen-printed electrode for the chronopotentiometric stripping analysis of cadmium(II) in wastewater and soil extracts.

Screen-printed carbon electrodes were fabricated with amino acid functionality by using in situ co-deposition of mercury and cysteine. The three-electrode configuration (graphite carbon working electrode, carbon counter electrode and silver/silver chloride reference electrode) incorporating a cysteine-modified working electrode exhibited good sensitivity towards cadmium(II). Several experimental variables affecting the sensor stripping response were characterised and optimised. These include cysteine and mercury concentrations, deposition time, deposition potential and stripping current. Surface analysis was also conducted using scanning electron microscopy (SEM) in order to characterize the electrode surface during cadmium analysis. The stripping chronopotentiometric response for cadmium(II) was linear in the concentration range 0.4-800 microg L(-1) when a deposition time of 2 min was used. A detection limit of 0.4 microg L(-1) was obtained using 0.025 M Tris-HCl buffer containing 0.1 M KCl (pH 7.4) as the supporting electrolyte. The analytical utility of the cysteine-modified sensor was demonstrated by applying it to cadmium analysis in various wastewater and soil samples collected from a contaminated site and extracted using acetic acid. The results obtained using the developed electrodes agreed satisfactorily with the values achieved using atomic absorption spectrometry and inductively coupled plasma mass spectrometry analysis. These results demonstrate the feasibility of using this type of sensor for cadmium analysis.

Cadmium↗
PubMed2000

Modified screen-printed electrodes for the investigation of the interaction of non-electroactive quinazoline derivatives with DNA.

Five morpholino-quinazoline derivatives have been investigated voltammetrically using a competition with the tris(o-phenanthroline) cobalt(III) redox marker for the accumulation at dsDNA modified screen-printed electrodes. An association of quinazolines with DNA was observed at the modified electrodes polarized by the negative potential of -0.4 V vs. Ag/AgCl. This was confirmed by a potentiometric stripping analysis based on the DNA guanine signal. Calibration curves for quinazolines within a concentration range of micromol/L were obtained with DP voltammetry using 5 x 10(-7) mol/L Co(phen)3(3+) marker. The quinazolines exhibit no effect on the DNA complex with the fluorescent thiazole orange derivative TO-PRO-3. The role of the accumulation potential in the association interaction with DNA is discussed.

Calibration↗
PubMed2003

Are digital images good enough? A comparative study of conventional film-screen vs digital radiographs on printed images of total hip replacement.

The aim of this study was to evaluate the inter- and intra-observer variability and to find differences in diagnostic safety between digital and analog technique in diagnostic zones around hip prostheses. In 80 patients who had had a total hip replacement (THR) for more than 2 years, a conventional image and a digital image were taken. Gruen's model of seven distinct regions of interest was used for evaluations. Five experienced radiologists observed the seven regions and noted in a protocol the following distances: stem-cement; cement-bone; and stem-bone. All images were printed on hard copies and were read twice. Weighted kappa, kappa(w), analyses were used. The two most frequently loosening regions, stem-cement region 1 and cement-bone region 7, were closely analyzed. In region 1 the five observers had an agreement of 86.75-97.92% between analog and digital images in stem-cement, which is a varied kappa(w) 0.29-0.71. For cement-bone region 7 an agreement of 87.21-90.45% was found, which is a varied kappa(w) of 0.48-0.58. All the kappa values differ significantly from nil. The result shows that digital technique is as good as analog radiographs for diagnosing possible loosening of hip prostheses.

Arthroplasty, Replacement, Hip↗
PubMed1999

[Motif expressing soft print lenses. Effect on visual function].

BACKGROUND: Contact lenses which change the structure and color of the iris are used not only for many therapeutic situations but also for cosmetic reasons. The purpose of this study was to investigate whether such lenses cause impairment of visual functions. MATERIAL AND METHODS: In healthy volunteers with an uncorrected visual acuity of 20/20 a clear soft-fitting lens and a special effect soft contact lens (Crazy lens, Bach Optic, Cologne) were tested in changing sequence. The following parameters were studied: visual acuity, contrast sensitivity (MCT 8000, VisTech Cons., Dayton, Ohio), Goldmann visual field, mesopic vision (Nyktometer, Rodenstock, Munich), and subjective wear comfort on a scale from 1 (excellent) to 10 (poor). Statistical analysis was performed using the Wilcoxon test and the Mann-Whitney U-test. RESULTS: Nine volunteers with a mean age of 29.9 +/- 5.1 years were analyzed. Visual acuity was reduced to 0.9 +/- 0.23 in the Crazy lens group compared to 1.2 +/- 0.13 in the clear lens group. Mesopic vision without glare was reduced from 1:2.5 to 1:7.4. Goldmann visual field displayed a significant constriction of following isopters: III/4, I/4, and I/3. Contrast sensitivity was significantly reduced in a photopic condition with and without glare and in a scotopic condition without glare; there was, however, an increase in contrast sensitivity in a scotopic condition with glare. Furthermore a decrease in wear comfort from 2.8 +/- 1.4 with the clear fitting lens to 5.7 +/- 2.1 with the print-lens was found. CONCLUSION: The tested special-effect contact lenses are associated with a reduction of many visual functions, including visual acuity and contrast sensitivity. This may interfere in some wearers with the ability to drive a car.

Adult↗
PubMed1989

Histochemical localization of cysteine-rich proteins by tissue printing on nitrocellulose.

A rapid technique for the histochemical localization of cysteine-rich proteins in plant tissues was developed. It is based on the immediate transfer of proteins to nitrocellulose membranes when a fresh cut organ is pressed against the membrane surface. The print was labeled for cysteine-rich proteins by reduction and alkylation of cysteinyl residues with dansylated iodoacetamide [N-iodoacetyl-N'-(-5-sulfo-1-naphthyl)ethylenediamine]. The S-carboxymethylated proteins were visualized by their fluorescence when excited with 360 nm light.

Antimicrobial Cationic Peptides↗
PubMed1996

Parasites as host [corrected] evolutionary prints: insights into host evolution from parasitological data.

The close relationships which link parasitic organisms to their hosts have led to the use of parasites as biological tags. Most studies on this topic refer to parasites as host ecological tags. Recent development of molecular methods which give access to the genomic structures of populations have provided new information on the evolutionary biology of parasites. In this paper, we have attempted to review whether parasites can be considered as "host evolutionary prints", and focus our discussion on host biodiversity and biogeography.

Animals↗
PubMed1983

Visuospatial analysis of the printed word.

Aphasic individuals often lose the ability to analyze written information phonetically because of left hemisphere damage experienced through cerebrovascular accident (CVA) or head trauma. In this study, aphasic and normal adults demonstrated use of a right hemisphere visuospatial strategy to analyze printed whole works and word parts such as prefixes and suffixes. The performances of the two groups were similar, suggesting that the hypothesized strategy could be useful as a reading approach for aphasics.

Adult↗
PubMed1977

Immunofixation after electrofocusing: improved method for specific detection of serum proteins with determination of isoelectric points. I. Immunofixation print technique for detection of alpha-1-protease inhibitor.

An improved method is described for direct localization of human serum proteins in polyacrylamide gel with simultaneous determination of their isoelectric points (pI). The technique employs isoelectric focusing in thin-layer polyacrylamide gels to separate the serum proteins and the pH gradient is read at 4 degrees C with a dual-membrane surface microelectrode. Subsequently, the desired proteins are localized by immunofixation in the gel or by immunofixation-printing onto cellulose acetate strips soaked in specific antiserum. No sectioning of the electrofocused gel is necessary, and the entire technique can be completed in less than 14 h. When this method is applied to the detection of the genetic variants of alpha-1-antitrypsin (alpha-1-protease inhibitor) (A1Pi system), the results indicate that it can be used to specifically localize serum proteins whose pI's differ by as little as 0.01 pH units. The resolution afforded is especially evident in the analysis of A1Pi M variants.

Blood Proteins↗
PubMed1985

Dissociated hemispheric superiorities for reading stenography vs print.

In two lateralized tachistoscopic lexical decision experiments at different exposure durations, we found for high-frequency function words written in stenography a shift from a RVF advantage at long exposures to a LVF advantage at short exposures, while for the same words written in print a strong RVF effect persisted. We suggest that a reduction of exposure duration, together with the strong visuo-spatial features in stenography, activate right-hemispheric word recognition. Stenography, a non-orthographic and syllabic-ideographic writing system, could be a model to investigate different hemispheric reading processes in Western subjects.

Adult↗
PubMed1982

Identification of protein bands in polyacrylamide gel by protein printing.

Previously described methods for identification of proteins separated in cylindrical polyacrylamide gels have been found to be costly in time and antiserum and difficult to apply to small amounts of protein as are found in cerebrospinal fluid. We describe a method which involves printing of the proteins on the cut surface of the gel onto nitrocellulose paper. The protein bands of the imprint can then be identified using labelled antibodies. We have found this to be economical and quick, and it has permitted sensitive and reliable identification of proteins in unconcentrated cerebrospinal fluid and aqueous humour.

Blood Proteins↗
PubMed1995

In vivo genotoxic effects of smoking and occupational lead exposure in printing press workers.

The objective of the present study was to evaluate the genotoxicity of a combination exposure to lead and smoking in workers from the printing industry and also to examine the possible interaction between the two agents. Individuals were classified into 4 different groups: control group, lead-exposed group, smokers and the double-exposure group. Chromosomal analysis was carried out according to conventional methods. Our preliminary study shows that lead-exposed individuals had a significantly increased frequency of sister chromatid exchanges. Further, double exposure to smoking and lead inhibits mitosis.

Adult↗
PubMed1990

Readability and content analysis of print cholesterol education materials.

This article reports the results of an analysis of the readability levels and content of 38 print cholesterol education materials available from government, health agency, professional association, university and industry sources. Each item was characterized according to the primary intended audience (general public, public and screening participants, or those identified with elevated cholesterol and patients in treatment), size, length and appearance. Readability analysis was done using the SMOG and Fog Grading formulas and content analysis examined the presence of messages in each of nine key areas. The readability assessment revealed that the average reading grade level was close to Grade 11, which is too difficult for many adults. Content analysis suggested a need to better address other heart disease risk factors, portion size and the use of brand name food recommendations. Further practice and research needs are identified.

Evaluation Studies as Topic↗
PubMedDate not supplied

In vivo genotoxicity of alcohol consumption and lead exposure in printing press workers.

The objective of the present study was to evaluate the genotoxicity of a double exposure to alcohol and lead in subjects from the printing industry, and the possible interaction between the two agents. Individuals were classified into four different groups: controls, lead-exposed individuals, alcohol consumers, and lead-exposed alcohol consumers. Chromosomal analysis was carried out according to conventional methods and data on chromosome aberrations and sister chromatid exchanges (SCEs) were obtained for each individual. Alcohol consumers had a significant increase in the frequency of SCEs compared to the controls. Though there was an increase in the frequency of chromosome aberrations and SCEs in individuals exposed to lead, it was not significant. Statistical analysis did not reveal an interaction between alcohol and lead in either assay.

Adult↗
PubMed2005

Precise blood lead analysis using a combined internal standard and standard addition approach with disposable screen-printed electrodes.

We report here a highly accurate and efficient method for blood lead analysis (BLA) through the use of a disposable electrode. A new type of mercury-plated preanodized screen-printed carbon electrode, together with a thallium(III) internal standard, simplifies calibration and gives easily quantifiable signals for accurate BLA. A preanodization procedure improves the preconcentration ability of the working electrode through the effect of lead (Pb) complexing with an electrogenerated surface functional group, mainly >C=O. Under optimized conditions, the ratio of the anodic stripping peak currents of Pb and Tl (i.e., i(Pb)/i(Tl)) is linear against [Pb] in the window of 1-300 ppb with a correlation coefficient and detection limit (signal-to-noise ratio=3) of 0.999 and 0.23 ppb, respectively. This approach was used to analyze blood samples (n=55) from workers at a local battery factory. The results are consistent with those obtained from graphite furnace atomic absorption spectroscopy and confirm the applicability of the proposed method.

Carbon↗
PubMed2005

Electroaddressed immobilization of recombinant HIV-1 P24 capsid protein onto screen-printed arrays for serological testing.

A serological chemiluminescent biochip was designed based on screen-printed electrode arrays composed of nine 1-mm(2) electrodes. Arrays were shown to be produced with good batch-to-batch reproducibility (standard deviations of 4.4 and 12.0% for ferricyanide oxidation potential and current, respectively) and very good reproducibility within a particular array (2.0 and 7.5% standard deviations for the same controls). Electrode arrays were used to electroaddress various bioconjugate structures comprising a recombinant HIV-1 P24 capsid protein (RH24K) in polypyrrole film. Entrapment of RH24K preimmobilized onto maleic anhydride-alt-methyl vinyl ether copolymer was shown to be the more efficient immobilization procedure. This addressed sensing layer enabled the detection of anti-P24 antibodies at a concentration of 3.5 ng/ml through peroxidase-labeled anti-human immunoglobulin G reaction. The biochip was used to perform an HIV-1 serological test in human sera. HIV-1 seropositive and seronegative sera were easily discriminated using serum dilutions greater than 1/10,000.

Amino Acid Sequence↗
PubMed2005

Amperometric, screen-printed, glucose biosensor for analysis of human plasma samples using a biocomposite water-based carbon ink incorporating glucose oxidase.

This paper describes the optimisation of a screen-printing water-based carbon ink containing cobalt phthalocyanine (CoPC) and glucose oxidase (GOD) for the fabrication of a glucose biosensor. To optimise the performance of the biosensor, the loadings of the electrocatalyst (CoPC) and enzyme (GOD) were varied. It was found that the maximum linear range was achieved with a CoPC loading of 20% (m/m, relative to the mass of carbon) and a GOD loading of 628 U per gram of carbon. In our studies we chose to employ chronoamperometry, as this technique is commonly used for commercial devices. The optimum operating applied potential was found to be +0.5 V, following an incubation period of 60 s. The optimum supporting electrolyte was found to be 0.05 M phosphate buffer at pH 8.0, which resulted in a linear range of 0.2-5 mM, the former represents the detection limit. The sensitivity was 1.12 microA mM(-1). The effect of temperature was also investigated, and it was found that 40 degrees C gave optimal performance. The resulting amperometric biosensors were evaluated by measuring the glucose concentrations for 10 different human plasma samples containing endogenous glucose and also added glucose. The same samples were analysed by a standard spectrophotometric method, and the results obtained by the two different methods were compared. A good correlation coefficient (R(2) = 0.95) and slope (0.98) were calculated from the experimental data, indicating that the new devices hold promise for biomedical studies.

Biosensing Techniques↗