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Sebastiaan J. Van Hal - One of the best experts on this subject based on the ideXlab platform.
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Evaluation of the Alfred 60/AST Device as a Screening Test for Urinary Tract Infections
2016Co-Authors: Sophie Lahanas, George Stathopoulos, Raymond C.k. Chan, Sebastiaan J. Van HalAbstract:The performance of the Alfred 60/AST device, an automated bacterial culture device which uses Laser Nephelometry to detect and quantify bacterial growth, was evaluated. The instrument is effective at screening negative samples and is more reliable at detect-ing bacteria than yeasts. Microscopy can be used to reduce the false-negative numbers. Urinary tract infections (UTIs) are one of the most commoninfections diagnosed in community and hospital settings (1, 2). It is therefore not surprising that urine samples constitute the largest proportion of specimens tested in microbiology laborato-ries (2, 3). Culture remains the current gold standard for diagnosis ofUTI but has limitations. It is time- and labor-intensive. Considering that 70 to 80 % of urine samples are proven negative for UTI (2, 4, 5, 6, 7), a rapid screening method could reduce costs and turn-around times. Alternative methods based on chemical and flow cytometry have had mixed results (2, 4, 8). This study was de-signed to evaluate the utility of a fully automated bacterial culture device (Alfred 60/AST)which utilizes Laser Nephelometry to detec
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Evaluation of the Alfred 60/AST Device as a Screening Test for Urinary Tract Infections
Journal of Clinical Microbiology, 2013Co-Authors: Sophie Lahanas, George Stathopoulos, Raymond C.k. Chan, Sebastiaan J. Van HalAbstract:ABSTRACT The performance of the Alfred 60/AST device, an automated bacterial culture device which uses Laser Nephelometry to detect and quantify bacterial growth, was evaluated. The instrument is effective at screening negative samples and is more reliable at detecting bacteria than yeasts. Microscopy can be used to reduce the false-negative numbers.
Uta-christina Hipler - One of the best experts on this subject based on the ideXlab platform.
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Antibacterial properties of cyclodextrin-antiseptics-complexes determined by microplate Laser Nephelometry and ATP bioluminescence assay.
International journal of pharmaceutics, 2013Co-Authors: Susanne Finger, Cornelia Wiegand, Hans-jürgen Buschmann, Uta-christina HiplerAbstract:Cyclodextrins (CDs) are able to form inclusion complexes with other molecules, thereby, protecting these guest molecules from degradation, enhancing their biocompatibility or influencing their physiological distribution while retaining their activity. Here, antibacterial effects of CD-complexes with the antiseptics chlorhexidine diacetate (CHX), iodine (IOD) and polihexanide (PHMB) were determined using two different in vitro methods, microplate Laser Nephelometry and an ATP bioluminescence assay. Laser Nephelometry is a direct method for monitoring and evaluating growth of micro-organisms by measurement of the turbidity of the solution. In contrast, the ATP bioluminescence assay determines specifically the amount of metabolic active bacterial cells. The antibacterial effects of CD-antiseptics-complexes were examined for Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Staphylococcus aureus and Staphylococcus epidermidis and the results of both methods were compared in respect of calculated means of half maximal inhibitory concentrations (IC50) and statistical evaluated Pearson's correlation coefficients (r). It could be demonstrated that both methods showed a high comparability although they differ in the parameters tested. This study revealed that CD-complexes with CHX and PHMB were most effective against E. coli and the tested staphylococci. While CD-IOD-complexes obtained high activity against K. pneumoniae, P. aeruginosa was distinctly more resistant compared to the other bacteria.
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Analysis of the adaptation capacity of Staphylococcus aureus to commonly used antiseptics by microplate Laser Nephelometry.
Skin Pharmacology and Physiology, 2012Co-Authors: Cornelia Wiegand, Martin Abel, Peter Ruth, Uta-christina HiplerAbstract:Background: Bacterial colonization and infection are important factors in compromised wound healing. Antiseptics have become an alternative for antimicrobial applications as antibiotic resistance is increasing; they have multiple targets with a broad spectrum of activity. Hence, the risk for developing resistance should be low. However, concerns have been raised that their growing use may result in bacteria that are less susceptible. Methods: The capacity of common antiseptics such as silver nitrate, polihexanide, octenidine, chlorhexidine and polyvinylpyrrolidone (PVP)-iodine to induce adaptation in a Staphylococcus aureus strain was analyzed in vitro using microplate Laser Nephelometry. S. aureus was repeatedly incubated with the respective half maximal inhibitory concentration (IC50) over a time period of 100 days. The influence of the continued treatment was determined by in situ monitoring of changes in the dose-response curves and calculation of the current IC50 values for the substances tested. Results: During the experiment, S. aureus quickly adapted to high concentrations of the antibiotic mupirocin during repeated treatment. Moreover, a significant increase of the IC50 for silver nitrate was observed over time. On the other hand, no significant difference was observed for polihexanide or chlorhexidine. While the IC50 for octenidine was also found to increase significantly, although the change was only marginal, reiterated incubation with PVP-iodine led to a decrease in the IC50. Conclusion: Repeated treatment of S. aureus with polihexanide, chlorhexidine, octenidine and PVP-iodine did not trigger bacterial adaptation to these substances.
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Antimicrobial properties of cyclodextrin-antiseptics-complexes determined by microplate Laser Nephelometry and ATP bioluminescence assay.
International journal of pharmaceutics, 2012Co-Authors: Susanne Finger, Cornelia Wiegand, Hans-jürgen Buschmann, Uta-christina HiplerAbstract:Antimicrobial effects of substances can be determined with different methods that measure distinct parameters. Thus, a comparison of the results obtained can be difficult. In this study, two in vitro methods were employed to determine concentration and time dependent effects of cyclodextrin (CD)-complexes with the antiseptics chlorhexidine diacetate (CHX), iodine (IOD) and polihexanide (PHMB) on Candida albicans and Malassezia pachydermatis. Using both, microplate Laser Nephelometry and the ATP bioluminescence assay, it could be shown that CD-antiseptics-complexes tested exhibited significant antifungal effects with the exception of γ-CD-CHX in the case of C. albicans. Microplate Laser Nephelometry (MLN) is an optical method and enables a quantitative determination of particle concentrations in solution. By means of this method, microbial growth under influence of potential antimicrobial substances can be monitored over a prolonged time period. In addition, the antimicrobial activity was analyzed by measurement of the microbial adenosine triphosphate (ATP) content with a bioluminescent assay. The luminescent signal is directly proportional to the amount of ATP, and thus, a linear function of the number of living microbial cells present. Both methods were compared according to the half maximal inhibitory concentration (IC(50)) calculated and the statistical evaluation of Pearson's correlation coefficient (r). In summary, it could be demonstrated that both methods yield similar results although they differ in the parameter.
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Antimycotic influence of β-cyclodextrin complexes : In vitro measurements using Laser Nephelometry in microtiter plates
International Journal of Pharmaceutics, 2006Co-Authors: Moustafa M G Fouda, Uta-christina Hipler, Dierk Knittel, Peter Elsner, Eckhard SchollmeyerAbstract:Abstract To determine the in vitro susceptibility of fungal organisms to β-cyclodextrin (CD) complexes with the antifungal agents econazole-nitrate (EC) and ciclopirox-olamine (CI), a fast, rapid and simple method using Laser Nephelometry in 96-microtiter plate is used. The antimycotic influence of the complexes against Candida albicans DSM 11225 and Candida krusei ATCC 6258 species was determined using this method. A rapid inhibition and even killing of both fungi was observed only above certain concentrations of complex ranged between 12.5 and 100 μg/ml for β-CD–econazole complex (CD–EC), while for the complex with ciclopirox-olamine (CD–CI) the range was between 150 and 400 μg/ml. The stability constants of the CD complexes with the two antimycotic derivatives are given. In addition, the nephelometric method allows the determination of solubilities of active agents. Thus, the improvement of solubility of both antimycotic agents in PBS buffer solution was observed by complexation with CD.
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Antimycotic influence of beta-cyclodextrin complexes--in vitro measurements using Laser Nephelometry in microtiter plates.
International journal of pharmaceutics, 2006Co-Authors: Moustafa M G Fouda, Uta-christina Hipler, Dierk Knittel, Peter Elsner, Eckhard SchollmeyerAbstract:To determine the in vitro susceptibility of fungal organisms to beta-cyclodextrin (CD) complexes with the antifungal agents econazole-nitrate (EC) and ciclopirox-olamine (CI), a fast, rapid and simple method using Laser Nephelometry in 96-microtiter plate is used. The antimycotic influence of the complexes against Candida albicans DSM 11225 and Candida krusei ATCC 6258 species was determined using this method. A rapid inhibition and even killing of both fungi was observed only above certain concentrations of complex ranged between 12.5 and 100 microg/ml for beta-CD-econazole complex (CD-EC), while for the complex with ciclopirox-olamine (CD-CI) the range was between 150 and 400 microg/ml. The stability constants of the CD complexes with the two antimycotic derivatives are given. In addition, the nephelometric method allows the determination of solubilities of active agents. Thus, the improvement of solubility of both antimycotic agents in PBS buffer solution was observed by complexation with CD.
R L Alexander - One of the best experts on this subject based on the ideXlab platform.
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Comparison of Radial Immunodiffusion and Laser Nephelometry for Quantitating Some Serum Proteins
2015Co-Authors: R L AlexanderAbstract:complement C3c and C4 in serum by using a Laser neph-elometer coupled with a data processor, I compared these results with values obtained by an early-readout radial immunodiffusion method. Day-to-day precision was better for Nephelometry than for radial immunodiffusion for all proteins analyzed. The average coefficient of variation was 6.0 % for Nephelometry and 9.9 % for radial immunodif-fusion. Comparison of these methods gave ranked cor-relation coefficients of 0.945, 0.981, 0.932, 0.803, and 0.792 for lgG, IgA, 1gM,C3c, and C4, respectively. Neph-elometry gave significantly higher values than radial im-munodiffusion for lgG, IgA, 1gM,and C3c, and significantly lower values for C4 (p < 0.001). Part of this bias was found to be due to the equation programmed in the data pro-cessor for calculating the standard curves. Within 95
G.i. Smirnov - One of the best experts on this subject based on the ideXlab platform.
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Polarization effects in high-informative pulse Laser Nephelometry of dispersed biosystems
Proceedings of SPIE, 1999Co-Authors: Sergey S. Bednarjevsky, Vladimir Mezentsev, Yuri V. Veryasov, Georgi Y. Sazhinov, G.i. SmirnovAbstract:The model of the pulse Laser Nephelometry polarization methods of using in biotechnologies and ecology is elaborated. It is shown that informativity of the Laser Nephelometry measurements increases when polarization self- action effects of short pulses of the Laser radiation are taken into account by multiple scattering is dispersed biological media with high concentration of weighted particles. The soliton and simulton regimes of the polarization transformation of the Laser pulses have been investigated. Conditions of the modulation instability are determined of the pulse Laser radiation of arbitrary polarization in nonlinear scattering biomedia.
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Modern methods and systems for precise control of the quality of agricultural and food production
Precision Agriculture and Biological Quality, 1999Co-Authors: Sergey S. Bednarjevsky, Yuri V. Veryasov, Evgeniya V. Akinina, G.i. SmirnovAbstract:The results on the modeling of non-linear dynamics of strong continuous and impulse radiation in the Laser Nephelometry of polydisperse biological systems, important from the viewpoint of applications in biotechnologies, are presented. The processes of nonlinear self-action of the Laser radiation by the multiple scattering in the disperse biological agro-media are considered. The simplified algorithms of the calculation of the parameters of the biological media under investigation are indicated and the estimates of the errors of the Laser-nephelometric measurements are given. The universal high-informative optical analyzers and the standard etalon specimens of agro- objects make the technological foundation of the considered methods and systems.
Sophie Lahanas - One of the best experts on this subject based on the ideXlab platform.
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Evaluation of the Alfred 60/AST Device as a Screening Test for Urinary Tract Infections
2016Co-Authors: Sophie Lahanas, George Stathopoulos, Raymond C.k. Chan, Sebastiaan J. Van HalAbstract:The performance of the Alfred 60/AST device, an automated bacterial culture device which uses Laser Nephelometry to detect and quantify bacterial growth, was evaluated. The instrument is effective at screening negative samples and is more reliable at detect-ing bacteria than yeasts. Microscopy can be used to reduce the false-negative numbers. Urinary tract infections (UTIs) are one of the most commoninfections diagnosed in community and hospital settings (1, 2). It is therefore not surprising that urine samples constitute the largest proportion of specimens tested in microbiology laborato-ries (2, 3). Culture remains the current gold standard for diagnosis ofUTI but has limitations. It is time- and labor-intensive. Considering that 70 to 80 % of urine samples are proven negative for UTI (2, 4, 5, 6, 7), a rapid screening method could reduce costs and turn-around times. Alternative methods based on chemical and flow cytometry have had mixed results (2, 4, 8). This study was de-signed to evaluate the utility of a fully automated bacterial culture device (Alfred 60/AST)which utilizes Laser Nephelometry to detec
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Evaluation of the Alfred 60/AST Device as a Screening Test for Urinary Tract Infections
Journal of Clinical Microbiology, 2013Co-Authors: Sophie Lahanas, George Stathopoulos, Raymond C.k. Chan, Sebastiaan J. Van HalAbstract:ABSTRACT The performance of the Alfred 60/AST device, an automated bacterial culture device which uses Laser Nephelometry to detect and quantify bacterial growth, was evaluated. The instrument is effective at screening negative samples and is more reliable at detecting bacteria than yeasts. Microscopy can be used to reduce the false-negative numbers.
