Evaluation of four hematology and a chemistry portable benchtop analyzers using non-human primate blood

Background  Near patient testing (NPT) and point-of-care testing (POCT) using portable benchtop analyzers has become necessary in many areas of the medical community, including biocontainment.
Methods  We evaluated the Beckman AcT diff, Abaxis Vetscan HMII (two instruments), Abbott Cell-Dyn 1800, and Abaxis Vetscan VS2 for within-run precision and correlation to central laboratory instruments using non-human primates blood.
Results  Compared with the central laboratory instruments, the Beckman AcT diff correlated on 80%; the HMII instruments on 31% and 44%, the CD1800 on 31%, and the VS2 on 71% of assays. For assays with published manufacturers precision guidelines, the AcT diff met all nine, the HMII instruments met one and six of six, and the CD 1800 met one of six.
Conclusions  Laboratories using NPT/POCT must test their individual instruments for precision and correlation, identify assays that are reliable, and exclude or develop supplemental procedures for assays that are not.     

Quality of plasma cholesterol measurements in primary care.

Three surveys were made of the quality of plasma cholesterol measurements performed with a commercial desktop analyser (BCL Reflotron) in primary care. Each survey included three specimens, and results were received from 37, 61, and 69 participants. Although many participants obtained satisfactory results, 8.6% of the results differed by 1.0 mmol/l or more from the target values, and the overall between instrument dispersion of results was 1.3 times that between hospital laboratories. It was found that common sources of error were poor technique and the use of outdated reagent strips. Users of such instruments outside the laboratory need help and advice with training, and guidelines for this are provided. The main recommendations are that users should establish contact with a local clinical chemistry laboratory for training and support and should participate in external quality assessment schemes.     

Variation in pentobarbitone sleeping time in mice. 2. Variables affecting test results

The effect of some environmental factors on the pentobarbitone sleeping time (PST) in inbred strains of mice has been investigated. Age, dose level and fasting before the test significantly altered the PST while the source of the drug and regular handling of the mice had no effect. None of these factors affected strains differentially. Unsystematic effects such as litter differences contributed only a small proportion of the total variation in the experiments. The strain rankings were different from those obtained in some previous experiments. The effects of some of the environmental factors on the PST did not always agree with previous work. The implications of these results for the design of similar experiments and the relevance of baseline values in laboratory animals are discussed.     

Methodological considerations for the use of faecal nitrogen to assess diet quality in ungulates: The Alpine ibex as a case study

Faecal indices are used to describe spatiotemporal patterns of diet quality in wild herbivores, and near infrared spectroscopy methods (NIRS) distinctively reduce costs and labour compared to conventional chemical analyses. In this study we compared the prediction accuracy of faecal nitrogen (N), ash and fibrous fractions of a laboratory instrument (NIRS) with that of a lightweight portable instrument (VisNIRS) using faecal samples of Alpine ibex (Capra ibex). We then compared how different indices based on faecal N and fibrous fractions were able to detect the expected temporal trend and difference between sexes in diet quality, and verified whether the presumably lower accuracy of NIRS and VisNIRS (compared to wet chemistry) influenced the ability of indices to detect such trends. The laboratory NIRS was more accurate than the portable VisNIRS, especially for fibrous fractions. Predicted data from both instruments clearly identified the temporal trend identified by chemically analysed data, but only NIRS identified the small difference between sexes. Expressing faecal N as a proportion of organic matter (OM) or neutral detergent fibre (NDF) improved the power of the index as compared to expressing it as a proportion of dry matter (DM), irrespective of the method used to estimate the data. Faecal NDF contents followed the patterns expected from the variation of faecal N, while faecal acid detergent fibre (ADF) and especially lignin (ADL) followed contradictory patterns, which might be due to a selection of different forage sources rather than to changing quality of a homogenous forage source. We conclude that expressing faecal N as a proportion of OM is advised with wild herbivores faeces, where ash content can be biased by accidental soil contamination or ingestion. Faecal fibrous fractions are useful to complement faecal N and to avoid simplified interpretations of the results. For this purpose, NIRS methods can be extremely useful to predict multiple indices on large numbers of samples. VisNIRS portable instruments might be unable to detect subtle biological patterns in small numbers of samples. However, developing procedures for portable instruments outside laboratory facilities might further improve practicability, cost effectiveness, and, through allowing on-field predictions on large numbers of samples, power of statistical testing of diet quality indices.     

与医科学生谈实验动物标准化

实验动物标准化由实验动物生产条件的标准化、实验动物质量标准化、动物实验条件的标准化以及与之相适应的饲养管理规范化和动物实验规范化几个部分组成。实验动物法制化管理是实验动物标准化的保证。动物实验是医学生物学必需的是实验手段之一,用标准的实验动物进行标准的动物实验是科研实验的基本要求。     

Leveling the playing field: Evaluation of a portable instrument for quantifying balance performance

Balance is a complex, sensorimotor task requiring an individual to maintain the center of gravity within the base of support. Quantifying balance in a reliable and valid manner is essential to evaluating disease progression, aging complications, and injuries in clinical and research settings. Typically, researchers use force plates to track motion of the center of gravity during a variety of tasks. However, limiting factors such as cost, portability, and availability have hindered postural stability evaluation in these settings. This study compared the “gold standard” for assessing postural stability (i.e., the laboratory-grade force plate) to a more affordable and portable assessment tool (i.e., BTrackS balance plate) in healthy young adults. Correlations and Bland-Altman plots between the center of pressure outcome measures derived from these two instruments were produced. Based on the results of this study, the measures attained from the portable balance plate objectively quantified postural stability with high validity on both rigid and compliant surfaces, demonstrated by thirty-five out of thirty-eight observed postural stability metrics in both surface conditions with a correlation of 0.98 or greater. The low cost, portable system performed similarly to the lab-grade force plate indicating the potential for practitioners and researchers to use the BTrackS balance plate as an alternative to the more expensive force plate option for assessing postural stability, whether in the lab setting or in the field.     

不同全自动凝血仪检测结果的分析研究

目的:探讨不同全自动凝血分析仪检测结果是否具有可比性,同时对其检测结果临床可接受性进行评估,使不同全自动凝血分析仪检测结果标准化.方法:连续30天用SYSMEX CA- 1500及CA-7000全自动凝血分析仪同时检测并比对仪器配套定值质控物的PT、INR、APTT、FIB、TT值;同时连续30天利用两台仪器检测并对比新鲜血标本的PT、INR、APTT、FIB、TT值.结果:SYSMEX CA- 1500及CA-7000日间质控物各检测项目:PT、INR、APTT、FIB、TT变异系数均小于5％.CA- 1500及CA-7000全自动凝血分析仪检测新鲜血标本:PT、INR、APTT、FIB、TT统计分析结果,t检验其P值均＞0.05;相关系数r在0.993-0.999之间;两台仪器的偏差均符合1/2美国CLIA’88能力验证分析质量要求.结论:两台仪器PT、INR、APTT、FIB、TT的检测结果具有很好的相关性,经统计分析两台仪器检测结果无统计学意义.对不同凝血分析仪进行比对分析,不仅能够及时发现仪器存在的系统误差.而且使其检测结果具有很好的一致性,给临床可提供一个准确、可靠一致的实验室检测结果,使临床对疾病的诊断、疗效观察有一个统一的评判标准.     

A field method for the cephalometric x-ray study of skulls in early Nubian cemeteries

The cephalometer, a clinical and research instrument employed by the orthodontic profession to record standardized x-rays of the human skull, has been modified for research work in remote areas where the usual laboratory facilities are not available. This cephalometer was specifically designed to record cephalograms (head radiographs) on the living Nubian population and their extensive skeletal record. The cephalometer consists of a light, portable tripod stand and an aluminum beam to which is attached at one end a Wehmer cephalostat (head holder), and on the other end an isotope radiation source. Hence, the radiation source and the cephalostat were held in the standard relationship of five feet from source to the mid-saggittal plane of the cranium. Ytterbium-169, with a half life of 32.5 days, was used to expose the film. The isotope and the use of the new Experimental Polaroid X-ray Film permitted the x-ray examination of Nubian skulls with no conventional power source or darkroom facilities.     

Random marginal agreement coefficients: rethinking the adjustment for chance when measuring agreement

Agreement coefficients quantify how well a set of instruments agree in measuring some response on a population of interest. Many standard agreement coefficients (e.g. kappa for nominal, weighted kappa for ordinal, and the concordance correlation coefficient (CCC) for continuous responses) may indicate increasing agreement as the marginal distributions of the two instruments become more different even as the true cost of disagreement stays the same or increases. This problem has been described for the kappa coefficients; here we describe it for the CCC. We propose a solution for all types of responses in the form of random marginal agreement coefficients (RMACs), which use a different adjustment for chance than the standard agreement coefficients. Standard agreement coefficients model chance agreement using expected agreement between two independent random variables each distributed according to the marginal distribution of one of the instruments. RMACs adjust for chance by modeling two independent readings both from the mixture distribution that averages the two marginal distributions. In other words, both independent readings represent first a random choice of instrument, then a random draw from the marginal distribution of the chosen instrument. The advantage of the resulting RMAC is that differences between the two marginal distributions will not induce greater apparent agreement. As with the standard agreement coefficients, the RMACs do not require any assumptions about the bivariate distribution of the random variables associated with the two instruments. We describe the RMAC for nominal, ordinal and continuous data, and show through the delta method how to approximate the variances of some important special cases.     

Increased instrument intelligence--can it reduce laboratory error?

Recent literature has focused on the reduction of laboratory errors and the potential impact on patient management. This study assessed the intelligent, automated preanalytical process-control abilities in newer generation analyzers as compared with older analyzers and the impact on error reduction. Three generations of immuno-chemistry analyzers were challenged with pooled human serum samples for a 3-week period. One of the three analyzers had an intelligent process of fluidics checks, including bubble detection. Bubbles can cause erroneous results due to incomplete sample aspiration. This variable was chosen because it is the most easily controlled sample defect that can be introduced. Traditionally, lab technicians have had to visually inspect each sample for the presence of bubbles. This is time consuming and introduces the possibility of human error. Instruments with bubble detection may be able to eliminate the human factor and reduce errors associated with the presence of bubbles. Specific samples were vortexed daily to introduce a visible quantity of bubbles, then immediately placed in the daily run. Errors were defined as a reported result greater than three standard deviations below the mean and associated with incomplete sample aspiration of the analyte of the individual analyzer Three standard deviations represented the target limits of proficiency testing. The results of the assays were examined for accuracy and precision. Efficiency, measured as process throughput, was also measured to associate a cost factor and potential impact of the error detection on the overall process. The analyzer performance stratified according to their level of internal process control The older analyzers without bubble detection reported 23 erred results. The newest analyzer with bubble detection reported one specimen incorrectly. The precision and accuracy of the nonvortexed specimens were excellent and acceptable for all three analyzers. No errors were found in the nonvortexed specimens. There were no significant differences in overall process time for any of the analyzers when tests were arranged in an optimal configuration. The analyzer with advanced fluidic intelligence demostrated the greatest ability to appropriately deal with an incomplete aspiration by not processing and reporting a result for the sample. This study suggests that preanalytical process-control capabilities could reduce errors. By association, it implies that similar intelligent process controls could favorably impact the error rate and, in the case of this instrument, do it without negatively impacting process throughput. Other improvements may be realized as a result of having an intelligent error-detection process including further reduction in misreported results, fewer repeats, less operator intervention, and less reagent waste.     

Less invasive blood sampling in the animal laboratory: clinical chemistry and haematology of blood obtained by the Triatominae bug Dipetalogaster maximus

Dipetalogaster maximus (Dipmax), a blood-sucking bug belonging to the family Reduviidae, has been used to obtain blood samples, for example for clinical chemistry and haematology, in a variety of zoo animals and wildlife. Using this bug allows stress-free blood sampling as the bug is able to draw blood without the mammal noticing the bug. In laboratory animal science, the need for blood samples from unstressed animals may arise, especially in animal behaviour research. The use of Dipmax bugs may prove a valuable tool for this purpose. To validate the method, we compared an array of standard blood parameters sampled from New Zealand White rabbits, sampled either by the use of bugs or by the conventional method; puncture of vena auricularis caudalis. The overall hypothesis was that there was no significant difference in clinical chemistry and haematological parameters between the bug method and the conventional method. A total of 17 clinical parameters as well as 12 haematological parameters were measured and compared in New Zealand White rabbits. The results showed that for 13 of these 29 analysed parameters, the bug method and the conventional method did not give significantly different results, and the obtained results were thus directly comparable. For the remaining parameters the obtained results were significantly different. However, all parameters were measurable in the bug samples. The influences of the bug metabolism on these parameters are discussed.     

The effect of preweaning and postweaning housing on the behaviour of the laboratory mouse (Mus musculus)

Standard housing for laboratory mice severely restricts natural behaviour and the control that the animal has over its environment. Providing the cage with objects is a method that has been used to both increase environmental complexity, promote the performance of natural behaviour and provide greater controllability for the animal. This method of furnishing cages has mostly been studied in adult animals, and little is known about the influence that the preweaning environment has on the behaviour of mice as adults. This study aimed to investigate the effects on mice behaviour of preweaning and postweaning housing environment. In this experiment, 64 pairs of animals of the strain C57BL/6J were used. Half of the animals were born and reared until weaning in standard cages and the other half in cages twice the size of the standard and furnished with nesting material, a cardboard tube, a PVC nest box and a wooden chewblock. After weaning, half the animals in each group were changed to the other type of cage, whereas the other half remained in the same environment; in both cases they were kept in single-sex pairs of littermates. Behaviour during the dark, active period was studied through video recordings. We found no main effects of preweaning environment on behaviour; however, mice moved from furnished to standard cages at weaning showed a decrease in inactive behaviour at four weeks of age. Mice housed after weaning in standard cages spent less time inactive, and more time engaging in activities like feeding and drinking, self-grooming and allogrooming. A sex difference was also found, in that females showed a greater performance of exploratory behaviour as well as a greater prevalence of stereotypies. The use of different objects and locations within the furnished cage was also analysed at both ages. Results show that at eight weeks of age mice spent more time at the top of the cage, and that the use of the nest box (although not for resting) increased between four and eight weeks. Mice were found to use the nest box as a nesting site/sleeping place only at age four weeks, whereas they always used the nesting material for sleeping.     

A diet defined by its content of bovine milk exosomes and their RNA cargos has moderate effects on gene expression,amino acid profiles and grip strength in skeletal muscle in C57BL/6 mice

Exosomes are nanoparticles that transfer cargos from donor cells to recipient cells where they elicit changes in gene expression and metabolism. Evidence suggests that exosomes and their cargos are also absorbed from dietary sources such as bovine milk, and bovine exosomes promote the growth of myofibers in murine C2C12 myotube cell cultures. The aim of the current study was to determine whether the dietary intake of bovine milk exosomes alters strength, gene expression and amino acid profiles in murine skeletal muscles. Male and female C57BL/6 mice, age three weeks, were fed an AIN93G-based, exosome and RNA-depleted (ERD) diet for six weeks; controls were fed an exosome and RNA-sufficient (ERS) diet. Variables of feeding behavior, metabolism, grip strength, liver and kidney function, amino acid profiles, and gene expression patterns were analyzed by using metabolic cages, grip strength analyzers, clinical chemistry analyzers, targeted LC/MS–MS, and RNA sequencing analysis. The diets had no effect on food and water intake, respiratory exchange rate, physical activity, grip strength, markers of liver and kidney dysfunction, and amino acid profiles in muscle. Only twelve and nine mRNAs were differentially expressed in skeletal muscle from female and male mice, respectively, fed ERD and ERS diets. The modest effect of the ERD diet on gene expression and levels of free amino acids in skeletal muscle is consistent with observations that bovine milk exosomes and their cargos accumulate in tissues other than skeletal muscle.     

Novel device for quick measurement of glucose in POCT areas without pre‐analytical steps based on a multi‐way glucose biosensor

Professional Point of Care testing demands rapid analysis and professional quality. To assure rapid analysis of high quality the analytical tool ideally should be able to work without sample pre‐treatment and should offer the opportunity to calibrate and/or control the analytical performance of the tool. In contrast to an enormous number of different disposable‐strips used for patient self monitoring today and based on an extended knowledge with respect to multi‐way biosensors used in laboratory analyzers we decided to develop a professional Point of Care Testing system for glucose analysis based on a multi‐way biosensor. The multi‐way glucose biosensor placed in the instrument for 30 days did reduce the lag time between blood withdrawal and availability of a result of lab quality in a bedside area to about 10 seconds. No pre‐analytical steps are necessary for measuring capillary whole blood, no crossing over was observed, and the data could be transferred into a laboratory information system or a hospital information system. Thus, we were able to realize tools for professional health control able to measure glucose values in laboratory quality at places outside laboratories: e.g., in doctor's offices, hospital wards, critical care units, and training units of athletes. By combining the advantages of laboratory analyzers (high quality and low sample price) and the advantages of disposable strips (simple procedure and immediate results after sample withdrawal) with the Glukometer 3000 and LactatProfi 3000 we did start to fill the gap between the two basic technologies available on the market for diagnosis today. Glukometer 3000 and LactatProfi 3000 are worldwide the first and only mobile glucose and lactate measuring instruments for decentralized locations based on multi‐way biosensors.     

Accuracy and Feasibility of Point-Of-Care White Blood Cell Count and C-Reactive Protein Measurements at the Pediatric Emergency Department

Background

Several point-of-care (POC) tests are available for evaluation of febrile patients, but the data about their performance in acute care setting is sparse. We investigated the analytical accuracy and feasibility of POC tests for white blood cell (WBC) count and C-reactive protein (CRP) at the pediatric emergency department (ED).

Methods

In the first part of the study, HemoCue WBC and Afinion AS100 CRP POC analyzers were compared with laboratory’s routine WBC (Sysmex XE-2100) and CRP (Modular P) analyzers in the hospital central laboratory in 77 and 48 clinical blood samples, respectively. The POC tests were then adopted in use at the pediatric ED. In the second part of the study, we compared WBC and CRP levels measured by POC and routine methods during 171 ED patient visits by 168 febrile children and adolescents. Attending physicians performed POC tests in capillary fingerprick samples.

Results

In parallel measurements in the laboratory both WBC and CRP POC analyzers showed good agreement with the reference methods. In febrile children at the emergency department (median age 2.4 years), physician performed POC determinations in capillary blood gave comparable results with those in venous blood analyzed in the laboratory. The mean difference between POC and reference test result was 1.1 E9/L (95% limits of agreement from -6.5 to 8.8 E9/L) for WBC and -1.2 mg/L (95% limits of agreement from -29.6 to 27.2 mg/L) for CRP.

Conclusions

POC tests are feasible and relatively accurate methods to assess CRP level and WBC count among febrile children at the ED.     

A method of reconstruction of clinical gas-analyzer signals corrupted by positive-pressure ventilation.

The use of sidestream infrared and paramagnetic clinical gas analyzers is widespread in anesthesiology and respiratory medicine. For most clinical applications, these instruments are entirely satisfactory. However, their ability to measure breath-by-breath volumetric gas fluxes, as required for measurement of airway dead space, oxygen uptake, and so on, is usually inferior to that of the mass spectrometer, and this is thought to be due, in part, to their slower response times. We describe how volumetric gas analysis with the Datex Ultima analyzer, although reasonably accurate for spontaneous ventilation, gives very inaccurate results in conditions of positive-pressure ventilation. We show that this problem is a property of the gas sampling system rather than the technique of gas analysis itself. We examine the source of this error and describe how cyclic changes in airway pressure result in variations in the flow rate of the gas within the sampling catheter. This results in the phenomenon of "time distortion," and the resultant gas concentration signal becomes a nonlinear time series. This corrupted signal cannot be aligned or integrated with the measured flow signal. We describe a method to correct for this effect. With the use of this method, measurements required for breath-by-breath gas-exchange models can be made easily and reliably in the clinical setting.     

Clinical chemistry reference database for Wistar rats and C57/BL6 mice

Clinical chemistry data are decisive for evaluating altered organ function or damage in experimental animals. Few publications provide reliable clinical chemistry reference intervals, and analytical methods are often not described. Here, we investigated common clinical chemistry values in adult male and female Wistar rats and C57/BL6 mice (n=30/group). Blood samples were taken and analysed for electrolytes, substrates, metabolites and enzymes. In addition, we investigated cystatin C, an important marker of glomerular dysfunction. All data were obtained using commercially available kits frequently employed in most clinical chemistry laboratories and compared with data from other studies, as well as with human data. Significant gender-specific differences were observed in rats (electrolytes, retention parameters and transaminases) and in mice (cholesterol, glucose). High variability was noted for sodium, potassium, glucose, creatine kinase, lactate dehydrogenase and transaminase levels. Both rodent species showed markedly higher alpha-amylase activity than humans. This report demonstrates significant differences between genders for many analytes in rats and for fewer parameters in mice. Some reference values displayed major discrepancies between rodents and humans.     

The validation of a portable force plate for measuring force-time data during jumping and landing tasks

The purpose of this study was to determine the reliability and validity of a portable force plate when analyzing jumping and landing tasks. Subjects performed 3 drop vertical jumps and 3 drop landings on both a standard strain gauge laboratory force plate and a portable force plate. In contrast to typical laboratory installed force plates, the portable 6-component force plate can be easily transported and used onsite at various training or data collection sites and incorporates Hall effect technology. The measured parameters included maximum force and time to maximum force for initial stance of the both tests, maximum takeoff force, and time to maximum takeoff force for the drop vertical jump. The Pearson correlation coefficients for the drop landing and the drop vertical jump for maximum force (r = 0.942, r = 0.940), time to maximum force (r = 0.891, r = 0.920) and for drop jump maximum jumping force (r = 0.971), and time to maximum takeoff force (r = 0.917) were all high and indicate that the force data collected by a resistor-type portable force plate provide similar measures to a standard strain-gauge laboratory force plate. Additionally, the within session reliability of the drop landing and the drop vertical jump measured by the portable force plate showed high interclass correlation coefficients for examined variables of 0.979 and 9.67 for maximum landing force and 0.917 and 0.920 for time to maximum landing force, respectively. The interclass correlation coefficients for the maximum takeoff force and time to maximum takeoff force during the drop vertical jump were 0.991 and 0.86. The results indicate the force and timing measurements from the portable force plate were both valid and reliable. Use of the portable force plate may facilitate methods of force measurement that can be applied out into the field and therefore a valuable tool for on site landing and jump force measurements in a variety of settings for large numbers of subjects.     

Response,use and habituation to a mouse house in C57BL/6J and BALB/c mice

Animal welfare depends on the possibility to express species-specific behaviours and can be strongly compromised in socially and environmentally deprived conditions. Nesting materials and refuges are very important resources to express these behaviours and should be considered as housing supplementation items. We evaluated the effects of one item of housing supplementation in standard settings in laboratory mice. C57BL/6JOlaHsd (B6) and BALB/cOlaHsd (BALB) young male and female mice, upon arrival, were housed in groups of four in standard laboratory cages and after 10 days of acclimatization, a red transparent plastic triangular-shaped Mouse House™ was introduced into half of the home cages. Animals with or without a mouse house were observed in various contexts for more than one month. Body weight gain and food intake, home cage behaviours, emotionality and response to standard cage changing procedures were evaluated. The presence of a mouse house in the home cage did not interfere with main developmental and behavioural parameters or emotionality of BALB and B6 male and female mice compared with controls. Both strains habituated to the mouse house in about a week, but made use of it differently, with BALB mice using the house more than the B6 strain. Our results suggest that mice habituated to the mouse house rather quickly without disrupting their home cage activities. Scientists can thus be encouraged to use mouse houses, also in view of the implementation of the EU Directive (2010/63/EU).