Desktop analysers: quality of results obtained by medical office personnel.

We carried out a study to evaluate the quality of results obtained by 14 nontechnical medical office personnel using desktop analysers. The instruments evaluated were the Reflotron analyser, the Seralyzer, the Vision analyser and the DT60 analyser. For precision studies low and high concentrations of control materials were used. For correlation studies the results obtained by the office personnel were compared with those obtained by a trained technologist. The coefficient of variation for the office personnel ranged from 3.0% to 8.1% with the Reflotron analyser, from 6.3% to 26.5% with the Seralyzer, from 1.0% to 4.1% with the Vision analyser and from 1.4% to 16.7% with the DT60 analyser. The correlation coefficient ranged from 0.970 to 0.997 with the Reflotron analyser, from 0.779 to 0.997 with the Seralyzer, from 0.975 to 0.998 with the Vision analyser and from 0.963 to 0.995 with the DT60 analyser. The proportion of results obtained by the office personnel that differed by more than 10% from those obtained by the technologist was 7% with the Reflotron analyser, 42% with the Seralyzer, 2% with the Vision analyser and 21% with the DT60 analyser. The instruments whose operation involves the least number of steps gave the most reliable results in the hands of medical office personnel.     

Quality control issues in point of care testing

* Quality Control (QC) in Point of Care Testing (PoCT) is often thought of as a complex issue; however intelligent system analysis can simplify matters and greatly increase the chances of a well controlled system. What we want to achieve is a QC program which adequately controls the PoCT system, but does not excessively contribute to the operating costs or complexity of maintaining a PoCT instrument, or network of instruments. * Don't neglect effective pre-analytical work: good documentation, operator training, monitoring, and analyser maintenance programs are essential, as for any analyser. * Look closely at your analyser: Is it a "laboratory type" instrument or cartridge or strip based? Can it perform multiple test types or a single test only? How is it calibrated? Does it have built in self-check capabilities or an electronic check cartridge? Is the sample in contact with the instrument? What are the cartridge/strip/reagent storage requirements? * Establish where the analysis is taking place and which system component is involved. * Tailor your QC program to target this component, but still check the system as a whole. * A common approach is to check cartridges/strips on delivery and run a QA sample at least monthly to check storage conditions and operator performance. If there is no independent electronic instrument check, daily QC checks are also recommended. * Don't be afraid to stray beyond conventional QC models if necessary. Some PoCT systems are not adequately controlled by the application of conventional QC alone.     

An automated method for counting and sizing fish eggs

This paper describes an automated method for counting and sizing fish eggs in the diameter range 200–2500 μm. Eggs, suspended in water, are pumped at a controlled rate through an electronic sensor which produces a voltage pulse which is proportional in amplitude to particle size. The sensor is connected to a HIAC Criterion PC-320 particle analyser which is in turn connected to a Tracor Northern pulse height analyser. This equipment separates the voltage pulses into 398 recording channels. An ACT 1 Sirius microcomputer is used to store the data, transform it to egg size and then produce a histogram of egg size distribution in 20-μm class intervals.
The method has a counting accuracy of 99.5 ± 0.5%. It has been compared with two manual methods of estimating egg numbers.     

An immunohistochemical and morphometric study on astrocytes and microvas culature in the human cerebral cortex

In this study, astrocytes and microvessels of the human cerebral cortex were analysed morphometrically with the aim of acquiring quantitative information on the glio-vascular relationships, considered to be of great importance in the formation and functioning of the blood--brain barrier. Immunohistochemistry for the astrocytic marker, glial fibrillary acidic protein, was used with a computerized image analysis system. The brain tissue was embedded using the progressive lowering of temperature method, and the image analyser was applied to semithin sections subjected to immunogold--silver staining and viewed by epipolarization microscopy. The results show that, in the human cerebral cortex, astrocytes cover 11.4% of the cortex area and that their perivascular processes are nearly as extensive as the vascular bed (0.8% versus 1.72% of the cortex area). These processes form a virtually continuous sheath around the vascular walls, only 11% of the vessel perimeter lacking this astrocytic glia covering. The present results, compared with previous unpublished data obtained by conventional immunocytochemical procedures on wax sections, indicate that low-temperature methods combined with gold--silver immunolabelling on semithin sections significantly improve the detection of immunoreactivity and the performance of the image analyser. This revised version was published online in November 2006 with corrections to the Cover Date.     

Counting total cell numbers microscopically on stained films

Two main sources of error in the conventional stained film cell count method, i.e. errors from imperfect spreading of the suspension and uneven distribution of cells in the film, have been eliminated by counting all the cells in the film. Staining solution and sodium alginate were added to the suspension before spreading over the slide. With a microsyringe, 20-μl suspension was spread in two bands of ca 1.7 mm × 60 mm each. Then total cells could be counted easily in the x 100 magnification field by moving the slide in one direction. Results were satisfactory. Coefficients of variation were 2.6 and 1.1% in two separate yeast determinations each with five replicates. For counting higher magnifications, a suitable image analyser for automating the method is believed worthy of study.     

Thin-layer chromatography — flame ionization detection and the quantitation of marine neutral lipids and phospholipids

A method is described whereby a complete analysis of individual neutral lipid and phospholipid classes in marine animal total lipid can be achieved using an latroscan TLC-FID analyser. The method involves separate analyses of two samples of total lipid in solvents designed to separate neutral and polar lipid classes, together with calibration by a composite standard similar in composition to the sample under analysis. The method does not depend on the degree of unsaturation of the fatty acids present, is rapid and compares well in accuracy with conventional combined gravimetric, colouritnetric, and densitometric procedures.     

A rapid analytical technique for the determination of energy expenditure by the doubly labelled water method

The doubly labelled water method involves the administration of water enriched in 2H and 18O followed by determination of the turnover rates of these isotopes. Since 18O is eliminated from the body as both CO2 and water, while 2H leaves only as water, the difference between the two turnover rates provides a measure of CO2 production and hence energy expenditure. Isotopic analysis by conventional stable isotope ratio analysis (SIRA) is labour intensive and time consuming, as it requires off-line conversion of water samples to gases (H2 and CO2) followed by sequential analysis for each of the two isotopes using the mass spectrometer. Lack of suitable automated instrumentation with the ability to process large numbers of samples has prevented routine application of the method. We describe here an automated technique in which body water samples (urine, saliva, breath water or milk) are analysed simultaneously for 2H and 18O. The single bench system comprises two mass spectrometer analysers, one for measuring 2H from H2 gas, the other for measuring 18O from the water vapour (masses 18, 20). Both analysers share a common heated inlet system into which microlitre quantities of the body fluids are injected from an autosampler (102 samples). The water vapour flows both directly to one analyser for 18O measurement and into a uranium reduction furnace for conversion to H2, prior to 2H measurement by the second analyser. Both analysers also share vacuum and electronic components, enabling savings in both space and cost. In this paper we present results illustrating performance characteristics and procedures for routine application to human subjects.(ABSTRACT TRUNCATED AT 250 WORDS)     

Biofiltration of composting gases using different municipal solid waste-pruning residue composts: monitoring by using an electronic nose

The concentration of volatile organic compounds (VOCs) during the composting of kitchen waste and pruning residues, and the abatement of VOCs by different compost biofilters was studied. VOCs removal efficiencies greater than 90% were obtained using composts of municipal solid waste (MSW) or MSW-pruning residue as biofilter material. An electronic nose identified qualitative differences among the biofilter output gases at very low concentrations of VOCs. These differences were related to compost constituents, compost particle size (2-7 or 7-20 mm), and a combination of both factors. The total concentration of VOCs determined by a photoionization analyser and inferred from electronic nose data sets were correlated over an ample range of concentrations of VOCs, showing that these techniques could be specially adapted for the monitoring of these processes.     

Calorimetric method for the monitoring and control of biocatalysed reactions

A method for determining the reactant concentration and biocatalyst activity during a biocatalysed reaction is described. The analyser functions by monitoring the temperature change of a sample of reaction mixture which is held under adiabatic conditions. Details are given of the successful application of the analyser to the monitoring and control of a fed-batch bioconversion by Rhodococcus ruber NCIMB 40757 of acrylonitrile to 42% (w/w) (4.37 M) ammonium acrylate and the wider application of the analyser to other bioconversions is considered.     

Apparatus for determining oxygen in small gas samples

A simple modification to an electronic O₂ analyser is described which enables accurate determination of O₂ in small gas samples. The response to O₂ concentration is linear over the range 0–21% by volume and as little as 0.07 μl of O₂ can be detected. Analysis of a 25 μl sample takes 25 s.     

Semi-automated fluorimetric method for the estimation of urinary catecholamines using high-performance liquid chromatography

A high-performance liquid chromatographic method for the quantitation of adrenaline and noradranaline in urine is described, using fluorescence detection. The effluent from the liquid chromatograph is led directly into an analyser to produce the fluorescent trihydroxyindoles from the catecholamines. The method is more reliable and specific than conventional fluorescence techniques. Both catecholamines can be detected at levels of 0.5 ng on the column.     

Blood lymphocyte volumes and diameters in patients with chronic lymphocytic leukemia and normal controls

The electronic modal lymphocyte volumes of 151 patients with chronic lymphocytic leukemia (CLL) and 305 normal controls were determined by the hydrodynamically focused multi-channel Coulter TF analyser. The mean volumes of the normally distributed groups were 166 +/- 19.3 (range 126-216) fl in patients with CLL and 206 +/- 14.4 (range 126 +/- 246) fl in normal controls. The calculated cell diameters were 6.8 (6.2-7.4) micron and 7.3 (6.8-7.8) micron respectively. Our data do not support previous reports about relations between cell size and clinical stages of the Rai and Binet classifications.     

Identification of ichneumonid wasps using image analysis of wings

Abstract. Image analysis was used to measure the morphological characters of wings of five species of Canadian Itoplectis (Ichneumonidae). The procedure to digitize and measure various elements of the wings with an image analyser is outlined. Specimens were assigned to species by discriminant analysis and independent univariate comparisons of 144 characters from cells, veins and vertices. All the fifty specimens used were assigned to the correct species by both methods. Image analysis of ichneumonid wings is an effective alternative to the conventional identification system.     

Reliability of measurement of oxygen uptake by a portable telemetric system.

The purpose of the present study was to check the reliability of measurements of oxygen uptake (VO2) using a newly developed portable telemetry system. This system (K2) consisted of a face mask, a flow meter, a gas analyser with a transmitter, and a receiver. The total mass for the subject to carry was about 850 g. Three experiments were carried out, firstly to check the reliability and reproducibility of the flow meter and the K2 gas analyser, secondly to check the accuracy of K2 by comparing it with the Douglas bag method (DB), and thirdly to apply K2 to sports activities. In the first experiment, the flow meter was highly accurate up to 180 l.min-1 with good reproducibility. The measurement error of the gas analyser was less than 2%. In the second experiment, there was no significant difference in the calculated ventilation between K2 and DB. The VO2 showed no significant difference between K2 and DB with some exceptions. In the third experiment, we succeeded in the measurement of VO2 during rowing on water. The measurement of VO2 during running and playing soccer was also possible. It would seem that the present system could well be a powerful tool in the field measurement of VO2 during various sports activities.     

In vivo measurement of glucose concentration with lasers.

Common polarimeters defined the concentration of an optically active sample by measuring the intensity of the light beam after it has passed through the analyser. Consequently, it can be stated that up to now, there have been the disadvantages of having a signal dependent on absolute light intensity. The new method that is described has a sensitivity that is in great measure independent of absolute light intensity, whereby only one light trace is necessary. The new principle uses no mechanical rotations. Instead, an electrical signal indicates the amount of optical rotation of the sample. The high sensitivity that can be reached is theoretically only limited by polarization noise. By going to the uttermost physical and electronic lengths, sensitivity values of more than 10(-5) degrees can be reached. Furthermore, the mechanical dimensions of the apparatus can be made very small by the application of a solid-state laser.     

A rapid method for the determination of microbial biomass by dry weight using a moisture analyser with an infrared heating source and an analytical balance

Aims: Microbial biomass is an important biotechnological parameter. The traditional method for its determination involves an oven‐drying step and equilibration to room temperature before weighing, and it is tedious and time consuming. This work studied the utilisation of a moisture analyser consisting of an efficient infrared‐heating module and an analytical balance for the determination of microbial biomass by dry weight. Methods and Results: The method duration depended on the sample volume and was between 7 and 40 min for sample volumes of 1–10 ml. The method precision depended on the total dry weight analysed – 10 mg of total dry weight being sufficient to achieve coefficients of variation of 5% or less. Comparison with the conventional oven method provided a correlation coefficient r² of 0·99. The recovery of an internal standard ranged between 94·2 and 106·4% with a precision of 1·39–4·53%CV. Conclusions: Validation revealed sufficient method accuracy, precision and robustness and was successfully applied to the study of yeast and bacterial growth kinetics. Techniques are discussed that allow for increased method precision at low biomass concentrations, and equations are provided to estimate required drying time and method precision based on sample volume and total sample dry weight, respectively. Significance and Impact of the Study: This work presents a rapid method for the determination of microbial biomass, allowing for the timely implementation of biomass‐based information in biotechnological and laboratory protocols.     

A Simple and Accurate Method for Infra-Red Gas Analyser Calibration

An alternative method for calibrating infra-red gas analysersis described which uses gas mixtures prepared with a gas mixingcircuit constructed from commonly available materials. It isshown that the maximum error in the gas mixture is about 1.5%,and possible improvements to the technique are discussed. Key words: Infra-red gas analyser, Calibration     

电镜图像定量分析肺毛细血管碱性磷酸酶在高压氧研究中的应用

采用碱性磷酸酶（ＡＬＰ）的电镜细胞化学方法,观察在高压氧条件下小鼠肺毛细血管ＡＬＰ活性的分布、活性强度与超微结构改变之间的联系,并用计算机图像定量测量方法对酶活性变化进行了２１个参数的定量分析。文中介绍了多参数图像定量分析方法及计算公式。     

Comparative study of the vasoreactivity of isolated human cortical and juxtamedullary glomeruli using verapamil and dopamine

The purpose of the present study was to compare the area variations of human cortical and juxtamedullary glomeruli after incubation with verapamil and dopamine. The glomeruli were isolated by sieving; areas were measured by a video analyser. The surface of the cortical glomeruli increases largely with verapamil (+14,3%) and dopamine (+11,5%). But, the area of the juxtamedullary glomeruli remains unchanged in the same experimental conditions. Evidence of such a vasoreactivity difference between cortical and juxtamedullary glomeruli will permit a better understanding in the regulation of renal haemodynamics.     

Evaluation of the spiral plate and laser colony counting techniques for the enumeration of bacteria in foods

Summary (1) In a parallel study, samples of food and dairy products, bacterial cultures and spore suspensions were examined by two operators using both the spiral plate and surface drop techniques for counting bacteria. (2) Statistical analyses of the results showed no differences between the methods at the 5% level of probability; regression and correlation coefficients were highly significant. A variation between paired counts of less than 0.5 log₁₀ cycles was given by 95% of the samples. (3) The replicate variances of both methods were <0.006, indicating good agreement betweeen duplicate plates. (4) An electronic laser counter used in this study was found to give comparable results (r=0.966) to the grid-method of colony counting in a substantially shorter time. (5) Analysis of operation times and material requirements for each method showed that significant savings in cost, time, space and support labour could be achieved with the spiral plate method over conventional techniques.