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At least 991 records · Page 55Linked to original sources
PubMed2005

Automated magnification calibration in transmission electron microscopy using Fourier analysis of replica images.

The magnification factor in transmission electron microscopy is not very precise, hampering for instance quantitative analysis of specimens. Calibration of the magnification is usually performed interactively using replica specimens, containing line or grating patterns with known spacing. In the present study, a procedure is described for automated magnification calibration using digital images of a line replica. This procedure is based on analysis of the power spectrum of Fourier transformed replica images, and is compared to interactive measurement in the same images. Images were used with magnification ranging from 1,000 x to 200,000 x. The automated procedure deviated on average 0.10% from interactive measurements. Especially for catalase replicas, the coefficient of variation of automated measurement was considerably smaller (average 0.28%) compared to that of interactive measurement (average 3.5%). In conclusion, calibration of the magnification in digital images from transmission electron microscopy may be performed automatically, using the procedure presented here, with high precision and accuracy.

Automation↗
PubMed2002

Comparison of two hemolysis procedures prior to an automated HbA(1c) immunoassay.

BACKGROUND: Hemoglobin A(1c) (HbA(1c)) is widely accepted as the most important biological parameter reflecting glycemic control in diabetic patients. Its measurement in clinical chemistry necessitates the use of reliable and robust methods. We studied here the influence of two hemolysis procedures on an automated HbA(1c) immunoassay using the Mira Plus analyzer. METHODS AND RESULTS: Whole blood was hemolyzed either manually, using an external manual procedure, or automatically on-board the analyzer. The results of imprecision studies showed comparable performance of both procedures, coefficients of variation (CVs) being slightly higher with the automated procedure (2.2-2.7% versus 1.7-2.1% in within-run experiments, and 2.4-3.5% versus 2.1-3.0% in between-run experiments). Comparison of results in 100 fresh samples showed acceptable correlation between the two procedures (r(2) = 0.94, y = 0.98x+0.43). Sedimentation of whole blood in sample tubes prior to automatic hemolysis did not alter the results. CONCLUSION: These data demonstrate that both procedures are suitable for routine use, with a higher practicability of the automated one. However, the values are not directly comparable, pointing out the critical role of every analytical step and the need for standardization and strict quality control of HbA(1c) assays.

Automation↗
PubMed2002

An integration architecture for the automation of a continuous production complex.

The development of integrated automation systems for continuous production plants is a very complicated process. A variety of factors must be taken into account, such as their different components (e.g., production units control systems, planning systems, financial systems, etc.), the interaction among them, and their different behavior (continuous or discrete). Moreover, the difficulty of this process is increased by the fact that each component can be viewed in a different way depending on the kind of decisions to be made, and its specific behavior. Modeling continuous production complexes as a composition of components, where, in turn, each component may also be a composite, appears to be the simplest and safest way to develop integrated automation systems. In order to provide the most versatile way to develop this kind of system, this work proposes a new approach for designing and building them, where process behavior, operation conditions and equipment conditions are integrated into a hierarchical automation architecture.

Automation↗
PubMed2000

Pesticide residue analysis in foodstuffs applying capillary gas chromatography with mass spectrometric detection. State-of-the-art use of modified DFG-multimethod S19 and automated data evaluation.

This paper focuses on recent developments in the author's laboratory and reports on the "ultimate" analysis scheme which has evolved over the last 20 years in our laboratory. This demonstrates the feasibility of screening analyses for pesticide residue identification, mainly by full scan GC-MS, down to the 0.01 ppm concentration level in plant foodstuffs. It is based on a miniaturized DFG S19 extraction applying acetone for extraction followed by liquid-liquid extraction with ethyl acetate-cyclohexane followed by gel permeation chromatography. The final chromatographic determination is carried out with a battery of three parallel operating gas chromatographic systems using effluent splitting to electron-capture and nitrogen-phosphorus detection, one with a SE-54 the other with a OV-17 capillary column and the third one with a SE-54 capillary column and mass selective detection for identification and quantitation. The method is established for monitoring more than 400 pesticides amenable to gas chromatography. These pesticide residues are identified in screening analyses by means of the dedicated mass spectral library PEST.L containing reference mass spectra and retention times of more than 400 active ingredients and also metabolites applying the macro program AuPest (Automated residue analysis on Pesticides) for automated evaluation which runs with Windows based HP ChemStation software. The two gas chromatographic systems with effluent splitting to electron-capture and nitrogen-phosphorus detection are used to check the results obtained with the automated GC-MS screening and also to detect those few pesticides which exhibit better response to electron-capture and nitrogen-phosphorus detection than to mass spectrometry in full scan.

Automation↗
PubMed2000

Cryogen free automated gas chromatography for the measurement of ambient volatile organic compounds.

An automated gas chromatographic system was constructed for measuring ambient volatile organic compounds (VOCs). Preconcentration of the VOCs was performed by using two separated sorbent traps of different combinations with each designated for either low or high boiling VOCs. Both traps and their associated valve systems were integrated as a complete system sharing a common sample inlet. Precise temperature controls for desorption relied on the use of a process controller with proportional-integral-derivative algorithm to throttle the current supply. No additional cryo-focusing stage prior to the column was needed owing to the flash heating capability for desorption. Other than the cryogen free preconcentration and focusing, the separation of VOCs of large volatility difference was also performed without cryogen. The system employed an Al2O3/KCl porous-layer open tubular column for separating C3-C7 compounds; and a DB-1 column for C6-C12. This automated GC system has been deployed in a Taiwan Environmental Protection Agency urban air quality monitoring station of Taiwan for continuous measuring C3-C7 ozone precursors. Excellent correlation between the car exhaust type of compounds measured by our GC system and carbon monoxide measured by a non-dispersive infrared spectrometer was observed, suggesting the automated GC system was robust and reliable.

Automation↗
PubMed2002

Strategy for the development of automated methods involving dialysis and trace enrichment as on-line sample preparation for the determination of basic drugs in plasma by liquid chromatography.

Among the sample preparation techniques, dialysis followed by clean-up and enrichment of the dialysate on a pre-column has proved to be a useful approach for the LC determination of drugs in plasma. By use of sample processors, like the ASTED system, such bioanalytical methods can be fully automated, the dialysis and trace enrichment steps being directly coupled to LC. In order to facilitate the development of such automated methods, a strategy based on a decision tree has been elaborated. After the selection of appropriate conditions for the LC analysis, the decision tree provides information about suggested starting conditions and guidelines for the optimisation of the most important parameters likely to influence analyte recovery and method selectivity. The plasma samples are dialysed on a cellulose acetate membrane in the static-pulsed mode and the dialysate is enriched on a trace enrichment pre-column packed with octadecyl silica or with a strong cation-exchange material. This decision tree is until now restricted to the analysis of basic drugs in plasma. In order to demonstrate the applicability of this method development strategy, an automated procedure based on the coupling of dialysis with trace enrichment has been developed for the LC determination of antifungal agents (clotrimazole, econazole and miconazole) in plasma.

Antifungal Agents↗
PubMed2003

Systematic error in automated in-tube solid-phase microextraction.

The widely employed configuration for automated in-tube solid-phase microextraction (SPME) involves modification of a commercial liquid chromatographic autosampler into an automated extraction device. This popular configuration is demonstrated to result in an inherent systematic error in the quantitation of analyte in a given matrix. The source of error is traced to the accumulation of analyte in the extraction and the pre-extraction segment (i.e., sample loop, metering valve and tubing prior to the metering valve) of the autosampler where the analyte comes in contact with the residual mobile phase. This results in cross-contamination due to sample/mobile phase mixing. The quantity of analyte accumulated in these segments is shown to consistently increase with the increasing number of draw/eject cycles. As a result of the accumulation, the amount of analyte recorded leads to inaccurate quantitative information, leading to overestimation of the limit of detection and limit of quantitation, when automated in-tube SPME is employed as an approach for sample enrichment. Insertion of a 100-microl air plug prior to extraction step was able to significantly minimize sample/mobile phase mixing of analyte with the residual mobile phase in the pre-extraction and extraction step, thus minimizing the systematic error.

Automation↗
PubMed2003

pO(2) measurements by phosphorescence quenching: characteristics and applications of an automated system.

An automated system for pO(2) analysis based upon phosphorescence quenching was tested. The system was calibrated in vitro with capillary samples of saline and blood. Results were compared to a conventional measuring procedure wherein pO(2) was calculated off-line by computer fitting of phosphorescence decay signals. PO(2) measurements obtained by the automated system were correlated (r(2) = 0.98) with readings simultaneously generated by a blood gas analyzer, accuracy being highest in the low (0-20 mm Hg) and medium pO(2) ranges (21-70 mm Hg). Measurements in in vivo studies in the hamster skin-fold preparation were similar to previously reported results. The automated system fits the phosphorescence decay data to a single exponential and allows repeated pO(2) measurements in rapid sequence.

Animals↗
PubMed2000

An automated test for measuring polymer biodegradation.

The biodegradability of polymer materials as evaluated by the modified Sturm test is labor-intensive, cumbersome and costly and also tends to cumulate errors. An automated system for the measurement of carbon dioxide would overcome many of these disadvantages. We describe here a method in which CO2 was determined by IR spectroscopy. We compared the results with those from trapping CO2 in a solution of barium hydroxide (Ba(OH)2) followed by manual titration. The automated system was more reproducible, less costly and more compact. The automated system could also be employed to measure the biodegradability of other substances such as oils and detergents.

Automation↗
PubMed1981

Computer analysis of visual field loss and optimization of automated perimetric test strategies.

Preliminary investigations of optimal target distribution patterns of automated perimetry were conducted. In the first study, frequency distributions of visual field defects were determined in glaucoma (260 scotomata) and optic nerve disease (110 scotomata) for approximately 30,000 visual field locations. The frequency distributions in glaucoma and optic nerve disease were different, and suggest guidelines for development of target distribution patterns to achieve optimal detection rates. The second study included computer simulation of 20 target distribution patterns currently used in manual and automated perimetry. Each distribution pattern was processed through the 370 glaucoma and optic nerve disease scotomata to assess detection performance. Both the density and distribution of target locations affected overall detection rates. In addition, some target configurations were more susceptible to false alarms than others. These data provide qualitative information for optimization of target distribution patterns in automated perimetry, and serve as a foundation for future quantitative studies.

Automation↗
PubMed2002

Automated analysis of foot-shock sensitivity and concurrent freezing behavior in mice.

Foot-shock is used in a variety of behavioral tasks either as a motivational stimulus, a way to characterize different rodents, or to test various pharmacological agents for their antinociceptive or analgesic effects. All these procedures need to assess foot-shock sensitivity either to rule out possible differences (when the shock is used as a motivational stimulus) or to use the differences to compare animals or treatments. In addition, many of the procedures that utilize foot-shock as a motivational stimulus evaluate freezing as an index of anxiety or fear. In the present study, data obtained by an automated computer system was compared with data obtained by human observers to validate the automated system for examining foot-shock sensitivity in mice. The different computer measures obtained for foot-shock sensitivity exhibited high correlations with human scoring at shock levels as low as 0.2 mA. The computer controlled analysis provided a non-subjective, quantifiable measurement of the foot-shock-induced response as well as freezing behavior. Automated data collection is an improvement over the methods of human visual observation in that the data collection is more standardized, efficient and consistent.

Animals↗
PubMed2002

Application of an automated specimen search system installed in a transmission electron microscope for the detection of caliciviruses in clinical specimens.

To evaluate the performance of an automated specimen search system in the detection of caliciviruses such as Norwalk-like viruses and Sapporo-like viruses, a suitable negative staining method was developed and the viruses were examined using the system installed in a transmission electron microscope (TEM). Clear images of the viruses were obtained by staining with 2% uranyl acetate at pH 4.0 as compared with 2% phosphotungstic acid staining at any pH. When the image parameter of 30+/-6 nm for the diameter of a single virus-like particle of 2% uranyl-acetate-stained Norwalk-like virus was set on the automated specimen search system, 95% of the virus-like particles that were counted by the conventional TEM technique were detected. The system was used to detect Norwalk-like viruses in five semipurified stool samples in which Norwalk-like viruses had already been detected by reverse transcription-polymerase chain reaction assay and conventional electron microscopy. The positive detection rate for Norwalk-like viruses, which had been counted by the conventional technique, ranged from 56.2 to 77.9% using this system. Our findings indicate that the automated specimen search system installed in a TEM is suitable for the detection of caliciviruses in semipurified stool samples. The system is useful for clinical diagnosis without the need for operator intervention.

Automation↗
PubMed1999

Development and validation of an automated, microscopy-based method for enumeration of groups of intestinal bacteria.

An automated microscopy-based method using fluorescently labelled 16S rRNA-targeted oligonucleotide probes directed against the predominant groups of intestinal bacteria was developed and validated. The method makes use of the Leica 600HR image analysis system, a Kodak MegaPlus camera model 1.4 and a servo-controlled Leica DM/RXA ultra-violet microscope. Software for automated image acquisition and analysis was developed and tested. The performance of the method was validated using a set of four fluorescent oligonucleotide probes: a universal probe for the detection of all bacterial species, one probe specific for Bifidobacterium spp., a digenus-probe specific for Bacteroides spp. and Prevotella spp. and a trigenus-probe specific for Ruminococcus spp., Clostridium spp. and Eubacterium spp. A nucleic acid stain, 4',6-diamidino-2-phenylindole (DAPI), was also included in the validation. In order to quantify the assay-error, one faecal sample was measured 20 times using each separate probe. Thereafter faecal samples of 20 different volunteers were measured following the same procedure in order to quantify the error due to individual-related differences in gut flora composition. It was concluded that the combination of automated microscopy and fluorescent whole-cell hybridisation enables distinction in gut flora-composition between volunteers at a significant level. With this method it is possible to process 48 faecal samples overnight, with coefficients of variation ranging from 0.07 to 0.30.

Adult↗
PubMed2004

Automated high through-put colocalization analysis of multichannel confocal images.

The laser scanning confocal microscope (LSCM) generates images of multiple labelled fluorescent samples. Colocalization of fluorescent labels is frequently examined. Here we present an example where localization of fluorescent analogues of cloned protein were referenced to fluorescent antibodies directed against the proteins of cellular compartments. Colocalization is usually evaluated by visual inspection of signal overlap or by using commercially available software tools, but there are limited possibilities to automate the analysis of large amounts of data. We developed a simple tool using Matlab to automate the colocalization procedure and to exclude the biased estimations resulting from visual inspections of images. The script in Matlab language code automatically imports confocal images and converts them into arrays. The contrast of all images is uniformly set by linearly reassigning the values of pixel intensities to use the full 8-bit range (0-255). Images are binarized on several threshold levels. The area above a certain threshold level is summed for each channel of the image and for colocalized regions. As a result, count of pixels above several threshold levels in any number of images is saved in an ASCII file. In addition Pearson's r correlation coefficient is calculated for fluorescence intensities of both confocal channels. Using this approach quick quantitative analysis of colocalization of hundreds of images is possible. In addition, such automated procedure is not biased by the examiner's subject visualization.

Automation↗
PubMed2002

Automated, nonrigid alignment of clinical myocardial contrast echocardiography image sequences: comparison with manual alignment.

Analysis of myocardial contrast echocardiography (MCE) images is currently done by manual techniques. The development of computationally efficient methods for aligning images provides an important first step toward the automation of MCE analysis. This is challenging because a nonrigid transformation correction is required. In this paper, we evaluate a state-of-the-art nonrigid alignment method on clinical MCE image sequences (n = 58) acquired on patients during rest and dipyridamole stress, using both B-mode intermittent ultraharmonic (IUH) imaging and real-time myocardial perfusion imaging (RTMPI). Using manual alignment as the reference, we show quantitatively that the automated method aligns images as well as a human observer. However, the new method is faster and more reliable than manual alignment and removes the need for an experienced physician to perform it. The automated technique can be used for quick poststudy off-line analysis and has the potential to be incorporated into an ultrasound machine.

Automation↗
PubMed1997

A new automated method of pain scoring in the formalin test in rats.

The formalin test is a valuable tool widely used in animal pain studies. We offer a new automated technique based on continuous recording of movements of animals injected in a hindpaw with formalin (5%). This method, based on image processing, allows the discrimination of specific pain-induced behaviors and general motor activity. The comparison of the pain scores evaluated by manual and automated methods showed the same biphasic response. This new process was validated by using compounds known to alter pain responses to formalin: morphine and a non-steroidal anti-inflammatory drug (ketoprofen). Morphine dose-dependently usually affects the two phases of formalin response with ED50 of 2.0 +/- 0.5 and 1.5 +/- 0.5 mg/kg s.c. for the first and the second phase, respectively. The injection of ketoprofen significantly decreased pain scores of the second phase but not those of the first phase. The specificity of the method was studied by determining the effect of diazepam. This sedative compound induced a decrease in pain scores as well as a decrease in motor activity parameters. These data show that this automated technique can be considered as a relevant, sensitive and specific tool which allows the easier use of the formalin test especially for the screening of analgesic drugs.

Analgesics, Opioid↗
PubMed2000

Automation of an absorbed enzyme immunoassay for the detection of Mycobacterium paratuberculosis antibodies for an eradication program.

As part of an ongoing Johne's disease eradication program by the state of Victoria, Australia, the Victorian Veterinary Pathology Services (VVPS) has been involved in testing over 150000 cattle samples per year for the presence of Johne's-specific antibodies. The Parachek kit (CSL, Victoria, Australia) has been used throughout the project. This method was automated using a Rosys 3300 and a Plato 7 (Dade/Behring Diagnostics) to pipette samples and the Behring ELISA Processor 3 (Dade/Behring Diagnostics) to wash EIA plates, add reagents, reads absorbances and perform data reduction of the results. Automation saved about 15h of labour per day, allowing one staff member to analyse up to 2000 samples per 8h shift compared to 800 samples using a manual protocol. Problems that were encountered include pipetting issues, the reading of the Paracheck endpoint, and excessive packaging of the kit. Maintenance, calibration and control of the analysers were an integral part of the process. VVPS, working in conjunction with CSL, suggested modification to the Parachek kit to make automation of the product more convenient. The approach resulted in a change in reagent volume and a reduction in packaging that reduced the cost of the test by 25%.

Animals↗
PubMed2001

Automated high-performance liquid chromatography method for the determination of rosiglitazone in human plasma.

A robust, fully automated assay procedure for the determination of rosiglitazone (I, BRL-49653) in human plasma has been developed. Plasma concentrations of I were determined using automated sequential trace enrichment of dialysates (ASTED) coupled to reversed-phase high-performance liquid chromatography. Sequential automated dialysis of human plasma samples was followed by concentration of the dialysate by trace enrichment on a C18 cartridge. Drug and internal standard, SB-204882 (II) were eluted from the trace enrichment cartridge by mobile phase (0.01 M ammonium acetate, pH 8-acetonitrile, 65:35, v/v) onto the HPLC column (a Novapak C18, 4 microm, 100x5 mm radial compression cartridge) protected by a Guard-Pak C18 cartridge. The compounds were detected by fluorescence detection, using an excitation wavelength of 247 nm, and emission wavelength of 367 nm. The lower limit of quantitation of the method was 3 ng/ml (200 microl aliquot) with linearity demonstrated up to 100 ng/ml. Within- and between-run precision and accuracy of determination were better than 10% across the calibration range. There was no evidence of instability of I in human plasma following three complete freeze-thaw cycles and samples can be safely stored for at least 7 months at -20 degrees C. This method has been successfully utilised to provide pharmacokinetic data throughout the clinical development of rosiglitazone.

Automation↗