Quick tests for the determination of ammonia in poultry litter

The objective of this work was to test the ability of various available quick tests to determine ammonia concentration of poultry litters. A total of 136 samples was collected from brood chambers of poultry houses. Samples were equally divided between surface samples (top 25 mm) and core samples. Samples were frozen until analysis but received no further processing. Samples were analyzed for ammonia by autoanalyzer (standard) and several quick tests (conductivity, Quantofix N-Volumeter, and Reflectoquant). In addition, samples were analyzed by near-infrared spectroscopy by scanning samples using a large-sample transport device on a FOSS-NIRSystems model 6500 (64 co-added scans from 400 to 2,498 nm). Results showed that, although ammonia could be determined with reasonable accuracy by near-infrared spectroscopy using data in the 1,100 to 2,498 nm spectral range (final calibration R2 of approximately 0.90), none of the quick tests, including near-infrared, worked as well as previously found with dairy manures. The best results were found using the Quantofix or Reflectoquant (R2 of approximately 0.75), and conductivity worked only with the core samples (R2 of approximately 0.75). It is believed that interferences due to the presence of uric acid (spectroscopy, Quantofix, and Reflectoquant) and sodium bisulfate used to treat the litter (conductivity) were the cause of the decreased accuracies as compared to results achieved previously with dairy manures.

High-throughput assay of oxygen radical absorbance capacity (ORAC) using a multichannel liquid handling system coupled with a microplate fluorescence reader in 96-well format

The oxygen radical absorbance capacity (ORAC) assay has been widely accepted as a standard tool to measure the antioxidant activity in the nutraceutical, pharmaceutical, and food industries. However, the ORAC assay has been criticized for a lack of accessibility due to the unavailability of the COBAS FARA II analyzer, an instrument discontinued by the manufacturer. In addition, the manual sample preparation is time-consuming and labor-intensive. The objective of this study was to develop a high-throughput instrument platform that can fully automate the ORAC assay procedure. The new instrument platform consists of a robotic eight-channel liquid handling system and a microplate fluorescence reader. By using the high-throughput platform, the efficiency of the assay is improved with at least a 10-fold increase in sample throughput over the current procedure. The mean of intra- and interday CVs was <or=15%, and the limit of detection and limit of quantitation were 5 and 6.25 microM, respectively.

Automatic flow system with voltammetric detection for diacetyl monitoring during brewing process

Diacetyl can be determined by adsorptive stripping voltammetry after derivatization with o-phenylenediamine. The method may be applicable to the determination of diacetyl in different foods, being a good alternative to other analytical methods. In this work an on-line automated analytical system for diacetyl determination in beer is described. A hanging mercury drop electrode voltammetric flow detector was used, and the analyte was determined without the traditional deoxygenation procedure. The method was successfully applied to the determination of diacetyl during beer fermentation and in the final product. The automation strategy used was based on a flow network similar to those used in multicommutated flow systems, with a pervaporation unit used for diacetyl separation. The developed system was tested in real conditions in the monitoring of brewing processes. The results obtained were similar to those obtained with the usual GC-ECD methodology in the 5-600 ppb range. The analytical rate of the developed method is about 12 determinations/h.

[Automated analyser of organ cultured corneal endothelial mosaic]

PURPOSE

Until now, organ-cultured corneal endothelial mosaic has been assessed in France by cell counting using a calibrated graticule, or by drawing cells on a computerized image. The former method is unsatisfactory because it is characterized by a lack of objective evaluation of the cell surface and hexagonality and it requires an experienced technician. The latter method is time-consuming and requires careful attention. We aimed to make an efficient, fast and easy to use, automated digital analyzer of video images of the corneal endothelium.

METHODS

The hardware included a PC Pentium III ((R)) 800 MHz-Ram 256, a Data Translation 3155 acquisition card, a Sony SC 75 CE CCD camera, and a 22-inch screen. Special functions for automated cell boundary determination consisted of Plug-in programs included in the ImageTool software. Calibration was performed using a calibrated micrometer. Cell densities of 40 organ-cultured corneas measured by both manual and automated counting were compared using parametric tests (Student's t test for paired variables and the Pearson correlation coefficient).

RESULTS

All steps were considered more ergonomic i.e., endothelial image capture, image selection, thresholding of multiple areas of interest, automated cell count, automated detection of errors in cell boundary drawing, presentation of the results in an HTML file including the number of counted cells, cell density, coefficient of variation of cell area, cell surface histogram and cell hexagonality. The device was efficient because the global process lasted on average 7 minutes and did not require an experienced technician. The correlation between cell densities obtained with both methods was high (r=+0.84, p<0.001). The results showed an under-estimation using manual counting (2191+/-322 vs. 2273+/-457 cell/mm(2), p=0.046), compared with the automated method.

CONCLUSIONS

Our automated endothelial cell analyzer is efficient and gives reliable results quickly and easily. A multicentric validation would allow us to standardize cell counts among cornea banks in our country.

[Determination of elastase 1 in plasma or serum by latex turbidometric immunoassay with automatic analyzer]

We developed a latex turbidometric immunoassay(LTIA) for elastase 1. The precisions were 1.0-2.8% intra-run and 1.2-2.9% inter-day. The dilution test showed good linearity between 80-4000 ng/dl. There was interference by bilirubin, hemoglobin, lipemia or rheumatoid factor. Serum and plasma elastase 1 measured by LTIA(y) showed significant correlations with those by RIA(x) (serum: y = 0.98x--18, r = 0.980, n = 64, plasma: y = 0.96x--19, r = 0.976, n = 61). It was confirmed that the values were elevated in patients with pancreatic disease compared to the normal level. These results demonstrate that the determination of elastase 1 in plasma or serum by this method is useful, simple and time-saving, when compared with that by RIA.

Can technology expedite the cervical cancer screening process? A Hong Kong experience using the AutoPap primary screening system with location-guided screening capability

We studied the usefulness of an automated screening instrument for processing Papanicolaou (Pap) smears to determine whether it could speed human examination by recording the time to screen 1,007 cervical Pap smears with an AutoPap primary screening instrument with location-guided screening (LGS) software and by conventional microscopic examination. We also assessed the accuracy of the methods to determine preparation adequacy, and we compared the diagnosis by each method. The AutoPap with LGS satisfactorily determined the adequacy of Pap smears and identified the marked abnormal cells for human examination. An accurate diagnosis was possible when only the marked cells were examined, and this method reduced the screening time to less than half that required for conventional screening. With low-grade squamous intraepithelial and more severe lesions as a threshold, there were 37 cases in the conventional group and 29 cases in the LGS group. With atypical squamous cells of undetermined significance as the threshold, there were 111 cases in the LGS group and 93 cases in the conventional group. The AutoPap with LGS can significantly speed the examination of Pap smears without lowering the detection rate of clinically important lesions, thus helping alleviate the cytotechnologist shortage.

Collection, storage, and filtration of in vivo study samples using 96-well filter plates to facilitate automated sample preparation and LC/MS/MS analysis

The benefits of high-throughput bioanalysis within the pharmaceutical industry are well established. One of the most significant bottlenecks in bioanalysis is transferring in vivo-generated study samples from their collection tubes during sample preparation and extraction. In most cases, the plasma samples must be stored frozen prior to analysis, and the freeze/thaw (F/T) process introduces thrombin clots that are capable of plugging pipets and automated liquid-transfer systems. A new approach to dealing with this problem involves the use of Ansys Captiva 96-well 20-microm polypropylene filter plates to collect, store frozen, and filter plasma samples prior to bioanalysis. The samples are collected from the test subjects, and the corresponding plasma samples are placed directly into the wells of the filter plate. Two Duoseal (patent pending) covers are used to seal the top and bottom of the plate, and the plate is stored at down to -70 degrees C. Prior to sample analysis, the seals are removed and the plate is placed in a 96-well SPE manifold. As the plasma thaws, it passes (by gravity or mild vacuum) through the polypropylene filter into a 96-well collection plate. A multichannel pipet or automated liquid-transfer system is used to transfer sample aliquots without fear of plugging. A significant advantage of this approach is that, unlike other methods, issues related to incomplete pipetting are virtually eliminated. The entire process is rapid since thawing and filtering take place simultaneously, and if a second F/T cycle is required for reanalysis, it is not necessary to refilter the samples (additional clotting was not observed after three F/T cycles). This technique was tested using monkey, rat, and dog plasma and sodium heparin and EDTA anticoagulants. To assess the possibility of nonspecific binding to the polypropylene filter, a variety of drug candidates from diverse drug classes were studied. Validation data generated for two Lilly compounds from distinct classes, before and after filtering, are presented in this paper as practical examples of this technique. While LC/MS/MS is the primary method of bioanalysis in our laboratory, the technique presented in this paper is applicable to other forms of detection as well.

Semi-automated enzymatic measurement of serum zinc concentration

OBJECTIVE

To measure serum zinc concentration by means of carbonic anhydrase reactivation using an automated analyzer.

METHODS

The zinc content of carbonic anhydrase (CA), whose cofactor is zinc, was removed by dialysis against pyridine 2 to 6 dicarboxylic acid and a pure apoenzyme was obtained. Serum proteins were precipitated with trichloroacetic acid (TCA) solution and the supernatant fraction of the sample was used to determine the zinc concentration. The negative effects of the precipitant on CA activity in the assay were completely removed, reaction conditions for maximal CA activity were provided and the color of the product was enhanced and stabilized. P-nitrophenyl acetate was used as the substrate and the change of absorbance of p-nitrophenol which was produced was followed at 400 nm. The initial rate of the esterase activity of CA was measured by using an automated analyzer. Analytical performance characteristics of the assay were determined. The zinc concentrations in serum samples of healthy subjects and patients were measured.

RESULTS

The enzymatic assay is accurate, sensitive, specific and is not affected by other metals. There was excellent agreement with the results obtained using an atomic absorption spectrophotometer (AAS) (y = 0.98X + 0.18, r = 0.99). Serum zinc concentrations were found to be higher in patients with vivax malaria, and lower in patients with cutaneous leishmaniasis than in healthy subjects.

CONCLUSION

The enzymatic method is suitable for semiautomated measurement of serum zinc concentration.

Source apportionment of gaseous atmospheric pollutants by means of an absolute principal component scores (APCS) receptor model

A multivariate statistical method has been applied to apportion the atmospheric pollutant concentrations measured by automatic gas analyzers placed on a mobile laboratory for air quality monitoring in Taranto (Italy). In particular, Principal Component Analysis (PCA) followed by Absolute Principal Component Scores (APCS) technique was performed to identify the number of emission sources and their contribution to measured concentrations of CO, NOx, benzene toluene m+p-Xylene (BTX). This procedure singled out two different sources that explain about 85% of collected data variance.

Performance characteristics of a point of care C-reactive protein assay

BACKGROUND

C-reactive protein (CRP) is a non-specific marker of inflammation that can be used for atherosclerotic risk assessment. This application requires increased precision at low CRP concentrations compared to traditional assays.

METHODS

The Micros CRP analyzer (ABX Diagnostics) is a small bench top device. Its limit of detection, limit of quantitation, linearity and imprecision were assessed. Method comparison studies were performed using samples both inside and outside the reference interval. Anticoagulant effects and the prozone effect were also evaluated.

RESULTS

The limit of detection was 0.1 mg/l. The method was linear from 2 to 60 and 0.3 to 60 mg/l using systematic error limits of 10% and 20%, respectively. The total imprecision was <8% for CRP concentrations from 0.7 to 9.1 mg/l. A prozone effect was seen at CRP concentrations >500 mg/l. Using samples from 120 apparently healthy adults, the Micros CRP method demonstrated excellent concordance with the BN II high sensitivity CRP (hs-CRP) method. The Micros CRP method compared well with a nephelometric method using samples with elevated CRP concentrations.

CONCLUSIONS

The Micros CRP method is adequate for atherosclerotic risk prediction in clinical practice but does not have adequate accuracy at CRP concentrations <2 mg/l for epidemiological studies.

Reactivity of macroprolactin in common automated immunoassays

OBJECTIVES

To evaluate a simple assay for macroprolactin for use with the Bayer Immuno 1 analyzer, and to compare the reactivity of macroprolactin in commonly used automated prolactin assays.

METHODS

Macroprolactin in serum was precipitated in a buffer containing 13.3% polyethylene glycol (PEG) 8000, redissolved, and assayed on the Bayer Immuno 1 for PRL. Presence of macroprolactin was confirmed in some sera by FPLC using a Pharmacia Superose 12 column, followed by prolactin assay of the fractions on the Immuno 1. Sera with and without macroprolactin were then also assayed on the Abbott AxSYM, Bayer Centaur, Beckman Access, and Roche Elecsys.

RESULTS

The PEG precipitation assay is simple and reproducible (CVs < 15%), and we established a normal range of < 20% precipitation of total PRL by PEG. The assay correlates well with the amount of macroprolactin separated by FPLC as a peak with a MW of approximately 180 kDa. Macroprolactin showed the following cross-reactivities in commonly used PRL assays: Roche Elecsys > Bayer Immuno 1 > Abbott AxSYM > Bayer Centaur > Beckman Access, with the Centaur showing more variability than other assays.

CONCLUSION

Macroprolactin can be easily quantitated using the Immuno 1 PRL assay after PEG precipitation. It cross-reacts to different degrees with common prolactin assays, and is a major source of variability between them.

Application of an improved biuret method to the determination of total protein in urine and cerebrospinal fluid without concentration step by use of Hitachi 7170 auto-analyzer

A biuret automated colorimetric assay for total protein in urine and cerebrospinal fluids was established. The procedures were as follows. Acidify all urine sample before analysis. Add precipitant Na(2)WO(4) to urine samples. After 10 min, centrifuge, decant the supernatant fluid, drain the inverted tubes on absorbent tissue, dissolve the precipitation with 0.1 mol/L NaOH, and finally adapt the reconstituted urine to the Hitachi 7170 analyzer. A cell-free cerebrospinal fluid sample produced by centrifugation can be inserted in an auto-analyzer for protein measurement directly. The program: mix 35 microl sample (CSF or reconstituted urine) and standard with 0.2 mol/L NaOH; incurable at 37 degrees C for 5 min, and real A1. Add concentrated biuret reagent, and 10 min later measure absorbance A2 at 546 nm vs. reagent blank. Secondary wavelength was 700 nm. The test results were calculated against a one-point standard. This biuret colorimetric method was relatively simple, fast, and accurate for the determination of protein in urine and cerebrospinal fluid, with a wide linearity extending from 0.125 g/L up to 6 g/L, had a good correlation with Benzethonium chloride turbidimetry technique, and was a practical routine method.

New automated chemiluminescent assay for erythropoietin

Erythropoietin (EPO) is a polypeptide hormone produced by the kidney that regulates erythropoiesis by controlling the proliferation and differentiation of erythroid progenitors in bone marrow. Assays for EPO are used to monitor dosage and response to human recombinant erythropoietin also may have diagnostic utility in the differential diagnosis of anemia and polycythemia. We evaluated an automated, chemiluminescent immunoassay for EPO (DPC Immulite) in terms of precision, linearity, interference, and correlation with reference assays. The Immulite assay demonstrated acceptable correlation with the reference immunochemiluminometric method (slope = 1.087, y intercept = 0.567, R value = 0.990). Within-run CVs ranged from 2.3% to 5.0%, while between-run CVs ranged from 4.1% to 9.5%. Linearity extended beyond the manufacturer's stated claims, and recovery ranged from 96.8% to 100.9% across the concentrations tested. No significant interference was noted with hemoglobin, bilirubin, or triglyceride. Overall, this method compares favorably with the existing immunochemiluminometric reference method and offers clinical laboratories an alternative for the analysis of erythropoietin.

Agilent 2100 bioanalyzer for restriction fragment length polymorphism analysis of the Campylobacter jejuni flagellin gene

The Agilent 2100 bioanalyzer (Agilent Technologies, Palo Alto, Calif.) utilizes capillary electrophoresis on a microchip device (LabChip 7500; Caliper Technologies, Mountain View, Calif.) that is capable of rapidly sizing small DNA fragments. To determine whether the system could replace conventional restriction fragment length polymorphism (RFLP) typing by agarose gel electrophoresis, we compared the analyzer with conventional flagellin RFLP for typing Campylobacter jejuni. Ninety-seven isolates representing 46 Fla types were initially analyzed. Correct Fla types were detected in 59% of the isolates. The major problem with the system was in resolving samples containing multiple DNA fragments differing from 8 to 20 bp. Overall, the bioanalyzer has the potential to replace conventional RFLP analysis by gel electrophoresis, but improvements in the chip separation are needed.

[Automated analysis for determination of PCBs in fish]

An automated analytical method for determination of polychlorinated biphenyls (PCBs) in fish was developed using supercritical fluid extraction (SFE) in combination with an automated sample preparation instrument (Prep) and GC/MS. By incorporating basic alumina with the sample in the extraction process, and optimizing the amount of carbon dioxide used, fish lipid was selectively reduced. The extract was cleaned up on a Florisil cartridge with Prep. The method was evaluated using naturally contaminated tissues and by comparison of automated analytical method results with those obtained by the conventional method. Mean recovery of PCBs from 3 kinds of fish including hairtail, mackerel and yellowtail were 69.8%, 90.2% and 81.1%, respectively. This method is less laborious and requires far less organic solvent than the conventional method, but produced comparable results.

[Investigations on the usefulness of the dry chemistry blood anaylsis system SPOTCHEM SP-4410in laboratory diagnosis of cattle]

The usefulness of the dry-chemistry blood analyzer, SPOTCHEM SP-4410, for analysis of bovine blood chemistry was studied in a veterinary clinic. The control serum Precipath-U, Boehringer-Mannheim, was used to measure precision within each run and between days. The coefficients of variation (CV) ranged between 1.54% and 4.86%, with the exception of albumin and creatine phosphokinase showing a CV of 6.3% and 10.03% for between-day precision. For methodological comparison bovine serum samples were assayed with both the SPOTCHEM SP-4410 and the automated blood analyzer HITACHI 705, which served as a wet-chemistry reference system. The following analytes were measured: glucose, urea, creatinine, total protein, albumin, total bilirubin and the enzymes AST, CPK and gamma-GT. For hemoglobin, which was measured in heparinized whole blood, the CO oximeter 855, CIBA-CORNING, was used as a reference system. The comparative analysis showed very good correlation in eight of ten parameters and their correlation coefficients (r) ranged between 0.962 and 0.998. Only the correlation coefficients of the analysis of total bilirubin (r = 0.903) and albumin (r = 0.771) were less satisfactory. The recovery test was carried out with the two parameters glucose and blood urea. The recovery of glucose was 93.7% and of urea 98.8%. The SPOTCHEM SP-4410 is easy to use and proved to be reliable and accurate, and therefore it seems to be useful for analysis of bovine blood samples.

Enzymatic microtiter plate-based nitrate detection in environmental and medical analysis

Our microtiter plate assay is based on the enzymatic reduction of nitrate by dissimilatory nitrate reductase from Pseudomonas stutzeri [EC 1.7.99.4]. Exogenous redox mediators like methyl viologen, methylene blue, and cibachron blue were applied to reduce nitrate reductase. Concentrations of 0.02-0.9 mM nitrate can be detected with +/-6% standard deviation, by using a photometric Griess reaction for the formed nitrite. Nitrate reductase is stable in the pH range 6.5-9.0 and works in the temperature range 4-76 degrees C. The assay shows no interferences with salt content up to 1 M chloride or 11 mM chlorate, and serum albumin content up to 50 mg/ml. The time demand of our two-step procedure is 20 min/100 samples. Nitrate reductase could be conserved on site of the wells of microtiter plates for at least 6 months at room temperature. The nitrate assay was applied in environmental and consumer goods analysis, and for medical diagnostics in human plasma samples.

Five useful approaches for generating more valid gel images of loss of heterozygosity and clonality analysis with an automated 377 DNA sequencer

The recently introduced fluorescence-based gene scan system for assessment of loss of heterozygosity (LOH) and clonality with an automated DNA sequencer has several advantages over the traditional method. However, the production of gel images with this system is subjected to more technical challenges, including the interference of autofluorescence, weaker and less consistent signals that result from the restricted well size and difficulties in sample loading. To minimize the impact of these technical difficulties, several unique strategies were used, including the following: elimination of fabrics or paper towels in the cleaning of gel plates and containers; use of a modified loading buffer; use of more concentrated gels; use of an innovative apparatus to clean gel wells before and after the prerun; and covering the black printer cartridge with a sheet of scotch tape. With these strategies, the authors have been able to consistently obtain gel images that can be presented as either densitometric graphs or as band patterns for direct visual assessment.

Comparison of automated short tandem repeat and manual variable number of tandem repeat analysis of chimerism in bone marrow transplant patients

Hematopoietic chimerism can be monitored in bone marrow transplant patients at DNA polymorphic sites. In this study, allele detection and quantification by ethidium bromide-stained agarose gels were compared with automated fluorescent sizing on an artificially mixed system and on chimeric post-transplant whole blood and sorted cell populations. A panel of five variable number of tandem repeats (VNTRs) were amplified and quantified visually on an ethidium bromide-stained gel. The ten short tandem repeats (STRs) were amplified as a multiplex polymerase chain reaction (PCR) and fluorescently detected on a DNA sequencer. Fluorescent band intensities were converted to fluorescent peak areas for allele quantification. Using mixed DNA of different proportions, both STRs and VNTRs showed linearity and appeared equally sensitive. However, case studies showed STRs to be more sensitive (<5%) than VNTRs (<10%). The STRs more accurately quantified the minor DNA component at low concentrations.

Stand-alone automated solutions can enhance laboratory operations

Clinical laboratory automation has developed over the past decade as one means of consolidating testing, reducing costs, and improving the effectiveness of laboratory testing. Most of the developments have been aimed at core clinical laboratory operations, and have primarily addressed preanalytical and analytical processing of traditional specimens arriving in blood collection or similar aliquot tubes. Much less attention has been given to specialized applications such as processing specimens for urine toxicology, and only recently have vendors attacked the problems associated with sorting and maintaining the laboratory's inventory of specimens. This report highlights selected developments in these areas, describes one approach to cost-effective custom platform development, and discusses the advantages and pitfalls to solving problems with laboratory automation.

The new era of automated immunoassay

Use of immunoassays and other ligand-binding assays in clinical diagnosis has increased dramatically during the last several years. Despite impressive technical advances, "mass production" of these assays in a routine laboratory still presents many difficulties. This review of ligand-binding assay technology highlights some recent developments, emphasizing challenges and possible solutions for cost-effective patient care.

Apolipoprotein B-100: employing the electrochemiluminescence technology of the Elecsys systems for the detection of the point mutation Arg(3500)Gln

Apolipoprotein B-100 (apo B-100) plays an essential role in lipoprotein metabolism where it is involved in the clearance of LDL particles from the bloodstream. The mutation Arg3500Gln in the apo B-100 gene impairs the binding of the LDL particles to the LDL receptor, resulting in elevated LDL-cholesterol levels in the blood which, in turn, fuel the development of premature atherosclerosis. Here we describe a rapid, automated test for the detection of the most frequent mutation in the apo B-100 gene. This PCR-based test employs electrochemiluminescence as detection technology and allows the reliable discrimination of all genotypes. The assay has been especially developed for the non-specialized routine clinical chemistry laboratory by employing an analyzer and chemistry often present in this type of labof1tory. Because of its low costs and easy handling the assay can be performed on a daily basis.

The quantitative measurement of autoantibodies to thyroglobulin and thyroid peroxidase by automated microparticle based immunoassays in Hashimoto's disease, Graves' disease and a follow-up study on postpartum thyroid disease

The aim of this study was to investigate the association between various autoimmune thyroid diseases and the presence of anti-TPO and anti-Tg antibodies using two novel automated microparticle based immunoassays developed for the AxSYM analyzer. Serum samples from 65 individuals with Hashimoto's Disease, 38 with Graves' Disease and 80 UK blood donors were assayed. In addition, samples were taken from 50 women known to be positive for TPO antibodies, for up to 24 weeks following delivery. Precision for both assays ranges from 5.7-9.1% CV, while analytical sensitivity was determined to be 1.0 IU/ml for Anti-Tg and 0.3 IU/ml for Anti-TPO. The Anti-TPO test showed positive results in 86% of Hashimoto's Disease and 87% of Graves' Disease. The figures obtained for Anti-Tg were 58% and 73% respectively. Specificity was 94% with Anti-TPO and 99% with Anti-Tg. The postpartum women were divided into 2 groups, group A remained symptomless while group B developed thyroid dysfunction. Within the 2 groups, medians calculated at each time point were compared between and within groups using the Mann-Whitney Rank Sum Test or the Kruskal-Wallis One Way ANOVA on Ranks. Anti-TPO baseline levels (week 6) were statistically different between both groups (median 36 vs. 167 IU/ml, p = 0.002). In group A, the median values increased from 36 to 87 IU/ml within the observation period, although the difference was not statistically significant. In group B, antibody titres showed a statistically significant increase from 168 IU/ml (week 6) up to 676 IU/ml after 20 weeks (p < 0.001). Anti-Tg baseline levels were not statistically different between the two groups. In group A, the median values did not change significantly over time (range: 47-86 IU/ml) whereas antibody titres in group B showed a statistically significant increase from 79 IU/ml (week 6) to 276 IU/ml after 24 weeks (p = 0.002). Results obtained indicate that these assays provide useful tools for the quantitative determination of autoantibodies in both primary diagnosis as shown with the Hashimoto's disease and Graves' disease samples and patient follow-up as demonstrated with the postpartum samples. The automation and high precision of the assays make them perfectly suited to routine diagnostic use.

Direct measurement of LDL-C in children: performance of two surfactant-based methods in a general pediatric population

OBJECTIVES

Several pediatric advisory groups have recommended selective screening for dyslipidemia in children. Low-density lipoprotein cholesterol (LDL-C) is measured clinically with the Friedewald calculation in fasting samples. Nonfasting measurement of LDL-C would be clinically useful in children.

DESIGN AND METHODS

In the present study, we examine the performance of two surfactant-based direct LDL-C assays in paired samples, fasting and nonfasting, from 100 children.

RESULTS

LDL-C in the fasting state was significantly lower with the Friedewald estimation: 2.43 +/- 0. 61 mmol/L, N-geneous (Genzyme Corp.) direct LDL-C: 2.30 +/- 0.59 mmol/L, and Roche (Roche Diagnostics) direct LDL-C: 2.32 +/- 0.57 mmol/L than with ultracentrifugation-dextran-sulfate-Mg(2+) precipitation (UC-DS): 2.47 +/- 0.64 mmol/L. Moreover, there was increased negative bias using nonfasting samples with N-geneous: 2. 25 +/- 0.56 mmol/L and Roche: 2.26 +/- 0.56 mmol/L compared with fasting UC-DS. Correlation with US-DS was highest for Friedewald (r = 0.974) and fasting N-geneous (r = 0.973), and lowest with nonfasting N-geneous (r = 0.849) and Roche in fasting (r = 0.891) and nonfasting samples (r = 0.747). The sensitivity at LDL-C concentration of 2.85 mmol/L for the two direct methods when either fasting or nonfasting samples were used, was lower than that obtained with Friedewald.

CONCLUSION

Overall, these direct LDL-C assays demonstrated limited utility in screening children but may be useful in the management of lipid disorders.

Analytic validation of an infrared milk urea assay and effects of sample acquisition factors on milk urea results

The objective of this study was to determine if milk samples, as they are routinely collected by Ontario Dairy Herd Improvement, would yield accurate milk urea results with an infrared assay. This investigation involved analytic validation of the infrared assay and assessment of the effect of DHI routine sample acquisition factors on milk urea results. Analytic validation of an automated milk urea assay was performed by assessing the relative accuracy and precision of milk urea results produced by the Fossomatic 4000 Milk Analyzer, an infrared method of analysis, compared with the Eurochem test, an accepted reference method. Results indicated that, when interpreted at the group level, milk urea results between the infrared method and the reference test were in good agreement. The two tests shared a similar and high level of precision. Milk urea concentrations obtained from composite (metered) milk samples, and not quarter stripping samples, were most representative of concurrent serum urea concentrations. The addition of bronopol preservative did not result in a numerically important change in milk urea concentrations. Storage of preserved metered milk samples for up to 4 d at either room temperature or by refrigeration, or for up to 3 d by freezing, did not result in changes in milk urea concentrations. We concluded that milk samples, as they are routinely collected and handled by DHI, are suitable for measurement of milk urea concentrations with the infrared method of analysis if data are interpreted at the group level.

Automated quantitative determination of the new renin inhibitor CGP 60536 by high-performance liquid chromatography

A fully automated high-performance liquid chromatography method with fluorescence detection for the determination of the renin inhibitor CGP 60536 in animal and human plasma and urine has been developed and validated. After addition of an internal standard, the compounds were automatically extracted from 400 microl of plasma or urine with methyl alcohol-acetic acid (99:1, v/v) on 100-mg Bond-Elut CN cartridges using the Gilson ASPEC system. The on-line chromatographic separation was performed on a LiChrospher 100 RP8 5-microm particle size packed analytical column (25x0.4 cm I.D.). The mobile phase consisted of acetonitrile-0.01 M potassium dihydrogenphosphate (65:35, v/v) at a flow-rate of 0.8 ml/min. The analytes were detected using a fluorescence detector at excitation and emission wavelengths of 280 and 330 nm, respectively. The limit of quantitation was established at 4.5 ng/ml in plasma (accuracy 106% and precision 1%), and 9.0 ng/ml in urine (accuracy 101% and precision 13%). The method was applied to the investigation of the pharmacokinetics of CGP 60536.

Preoperative screening for von Willebrand disease type 1: low yield and limited ability to predict bleeding

Type 1 von Willebrand disease (vWd) is the most common hereditary bleeding disorder. The objective of this study was to measure the von Willebrand factor antigen (vWf:Ag) in a large cohort of patients who underwent surgery to assess the role of a new rapid immunoassay in a screening procedure for vWd in preoperative conditions. We studied 832 consecutive patients (540 children, 292 adults) referred to the surgical departments. For each patient we determined the vWf:Ag level with two different assays, an enzyme-linked immunosorbent assay (ELISA)(Asserachrom vWf:Ag; Diagnostica Stago, France) and a rapid immunoassay (Liatest vWf:Ag; Diagnostica Stago). Using the reference test, we found 30 of 832 patients with a vWf:Ag value below the lower limits (21 U/dL to 46 U/dL). The coefficient of correlation between the two tests was 0.77 (P = .001). When receiver operating characteristic curves were used, the cutoff value calculated to detect vWf:Ag defect with the rapid assay was 68.5 U/dL, leading to 0.36% false negatives and 9.7% false positives. Thus the rapid immunoassay appears to be a useful and easy method that is adaptable to urgent situations. Among the 30 patients with low values in ELISA, 8 had personal or familial bleeding history. Repeat blood samples confirmed the diagnosis of vWd in 5 cases, leading to a prevalence of vWd type 1 of 0.6%. However, in our series the absence of severe bleeding complications raises the question of the screening and the management of patients bearing a type 1 Willebrand disease during surgery.

A continuous assay for the spectrophotometric analysis of sulfotransferases using aryl sulfotransferase IV

We have developed a continuous spectrophotometric coupled-enzyme assay for sulfotransferase activity. This assay is based on the regeneration of 3'-phosphoadenosine-5'-phosphosulfate (PAPS) from the desulfated 3'-phosphoadenosine-5'-phosphate (PAP) by a recombinant aryl sulfotransferase using p-nitrophenyl sulfate as the sulfate donor and visible spectrophotometric indicator of enzyme turnover. Here recombinant rat aryl sulfotransferase IV (AST-IV) is expressed, resolved to the pure beta-form during purification, and utilized for the regeneration. The activity of betaAST-IV to catalyze the synthesis of PAPS from PAP and p-nitrophenyl sulfate is demonstrated via capillary zone electrophoresis, and the kinetics of this reverse-physiological reaction are calculated. betaAST-IV is then applied to the coupled enzyme system, where the steady-state activity of the commercially available Nod factor sulfotransferase is verified with an enzyme concentration study and substrate-specificity assays of N-chitoses. The potential applications of this assay include rapid kinetic determinations for carbohydrate and protein sulfotransferases, high-throughput screening of potential sulfotransferase substrates and inhibitors, and biomedical screening of blood samples and other tissues for specific sulfotransferase enzyme activity and substrate concentration.

Evaluation of four automated methods for determination of whole blood cyclosporine concentrations

Cyclosporine is a widely used and potent immunosuppressant drug with a narrow therapeutic index. Therefore, cyclosporine concentrations should be monitored closely. Various automated immunologic methods for cyclosporine whole blood determinations are available. Two new methods, fluorescence polarization immunoassay (FPIA) for the AxSYM by Abbott Laboratories, Chicago, IL, and the cloned enzyme donor immunoassay (CEDIA) by Boehringer Mannheim, Mannheim, Germany, have been introduced. In addition, Dade Behring improved its enzyme multiplied immunoassay (EMIT) assay. The present study evaluated all 3 new methods in comparison with high-performance liquid chromatography (HPLC) and the FPIA for the TDx analyzer. We measured whole blood cyclosporine concentrations of 179 samples obtained from 127 patients after kidney, bone marrow, heart-lung, and liver transplantation. All 4 automated immunologic methods can be used for routine measurement of cyclosporine whole blood concentrations. Disadvantages, such as higher cross-reactivity (Abbott TDx, CEDIA) or a limited linearity range (EMIT), are accompanied by advantages, such as a high precision (Abbott TDx) or an easy sample handling procedure (CEDIA). Information presented in this article should help to find the most adequate cyclosporine method for each medical laboratory.

Automated kinetic exclusion assays to quantify protein binding interactions in homogeneous solution

A method was developed for the quantification of protein-ligand interactions in which the free protein present in homogeneous reaction mixtures was separated and quantified using a KinExA immunoassay instrument. Separation was achieved by rapid percolation of the reaction mixture over a column of microbeads whose surfaces were coated with an immobilized form of the ligand. The protein thus captured was quantified using a fluorescently labeled anti-protein antibody. The features of this new method were illustrated using a model system in which each of the principal reagents was covalently labeled with a different fluorescent molecule: mouse monoclonal anti-biotin primary antibody (fluorescein), biotin (B-phycoerythrin), and goat anti-mouse polyclonal secondary antibody (indodicarbocyanin). Values for the equilibrium and kinetic rate constants for the binding between the anti-biotin antibody and biotin conjugated with B-phycoerythrin were determined and shown to be independent of whether the fluorescent label was located on the primary or secondary antibody. Equilibrium binding experiments conducted with (F(AB))(2) and corresponding F(AB) fragments showed that the valency of the binding protein had no influence on the value of the dissociation constant. The values of the equilibrium and rate constants obtained by this new method are those for the binding reaction in homogeneous solution; the immobilized ligand is only a tool exploited for the separation and quantification of the free protein.

Interference of Hb-H disease in automated reticulocyte counting

Hb-H disease is a form of alpha-thalassemia commonly found in south-east Asia. In this condition, numerous Hb-H bodies are found in erythrocytes using reticulocyte staining preparations. This is the first study addressing the possible interference of Hb-H inclusions in automated reticulocyte counting. In this study, seven Hb-H disease samples were tested. Results obtained by the visual method and the Technicon H*3 automated method agreed relatively well. This was in contrast to the Coulter STKS automated method which generally gave lower results. Furthermore, when the incubation time was extended to 180 min in the Coulter STKS method, two Hb-H disease samples gave results several-fold higher than those obtained using the 60 min incubation time. These discrepant results were likely to have been caused by the analyser using the wrong threshold to separate reticulocytes and mature erythrocytes. High and low interference in Hb-H disease samples was observed in the Coulter STKS automated reticulocyte method. Laboratories should be aware of this potential problem, particularly when samples are from patients of Asian origin.

Pseudo-reticulocytosis as a result of malaria parasites

Recently fully automated methods for enumerating reticulocytes have become available as an integral function in routine haematology analysers. In such methods, all intraerythrocytic nucleic acid is stained and can be regarded as representing reticulocytes. It has previously been shown that Howell-Jolly bodies may be counted as reticulocytes in automated flow cytometric methods. In the present paper, data from two patients are described indicating that severe malaria infection may lead to falsely increased reticulocyte counts, at least in the CELL-DYN(R) 4000 haematology analyser. In this instrument, the intraerythrocytic nuclear material of the parasites will be stained and counted as reticulocytes. This phenomenon appears to be independent of the type of Plasmodium infection. Clinical haematology laboratories should be aware of this potential source of pseudo-reticulocytosis.

Performance characteristics of IMMULITE TPS: a comparison with TPS IRMA

This paper describes an automated immunoassay for the measurement of TPS developed for the IMMULITE. The IMMULITE system is a fully automated continous random access analyzer, which uses enzyme-amplified chemiluminiscent as the detection system. The IMMULITE TPS assay is a sequential, two-site chemiluminiscent enzyme immunometric assay designed for the quantitative measurement of TPS in serum. The IMMULITE TPS assay covers a clinical concentration range of 20-2400 U/L, with a lower detection limit of 6 U/L. A serum method comparison (n = 340) to the TPS IRMA assay demonstrates a correlation coefficient of 0.961 and a slope of 1.04. Samples run on IMMULITE TPS assay exhibit linearity upon dilution where recovered values fall within 15% of the theoretical sample value. The intra-assay precision of the IMMULITE TPS assay ranged from 3.3-4.7%, while the interassay precision ranged from 3.9-6.0%. By using different methods (immunoradiometric assay vs chemiluminiscent enzyme-labeled immunometric assay, one-step procedure vs sequential two-step procedure, manual vs fully automated procedure) the two TPS tumor marker tests used in this study gave quite comparable determinations for the sera from the cancer patients.

Automated Cobas Core PSA assays: sensitive, precise, and specific measurement of PSA-total and PSA-total/PSA-free ratio

We describe the analytical performance of the newly developed Roche Cobas Core PSA Total EIA and the Cobas Core PSA Free EIA. The assays are designed for the random access immunochemistry analyzer Cobas Core. Both assays are highly precise (CV's < 4%) and highly sensitive (PSA Total: analytical sensitivity < 0.02 ng/ml; PSA Free: < 0.01 ng/ml). The PSA Total EIA measures PSA-ACT and PSA free equimolarly. The assays are standardized against the reference material of the Stanford group and correlate very well with the designated golden standard Hybritech Tandem-R assays. The high-dose-hook is beyond 20,000 ng/ml and 4500 ng/ml for the PSA Total and PSA Free assay, respectively. In summary, the data indicate clearly the reliability of the measuring system and the achievement of the demands of PSA diagnostics.

Development of a new automated enzyme immunoassay for the determination of neuron-specific enolase

Neuron-specific enolase (NSE) represents the gamma gamma- and alpha gamma- isoforms of the dimeric glycolytic enzyme enolase. NSE is predominantly found in neurons and neuroendocrine cells and has proven to be a marker for tumors derived from these cells. It is widely accepted in the monitoring of patients with small cell lung cancer and is also of value as an aid in diagnosis. Recently it has become of interest in the monitoring of brain damage. Monoclonal antibodies against gamma-enolase were raised in mice and selected for optimal performance on the Cobas Core enzyme immunoassay system. The antibody combination of choice was MAb 18E5 for capturing and MAb 84B10 for detection which is accomplished by using a horseradish peroxidase conjugate and the substrate 3,3',5,5'-tetramethylbenzidine. The resulting assay is a one-step enzyme immunoassay of the sandwich type. It is performed on the fully automated Cobas Core immunoassay analyzer with a total assay time of 45 min. The sample volume is 10 microliters. Calibration is done by a 1-point recalibration using a lot-specific master calibration curve provided with the kit. The dynamic range is 0-200 ng/ml. The analytical detection limit (standard 0 + 2SD) of the Cobas Core NSE EIA II was 0.1 ng/ml. Intra- and interassay coefficients of variation were < 5% and < 6%, respectively. A Hook Effect was not observed up to a concentration of 20'000 ng/ml. Test results correlated closely with the well established polyclonal Cobas Core NSE EIA (r = 0.99). In summary, the Cobas Core NSE EIA II is a rapid, reliable and convenient test for measuring NSE in human serum.

LIAISON hCG--an automated chemiluminescent immunoassay for the determination of human chorionic gonadotropin (hCG)

An immunoassay utilizing chemiluminescence and paramagnetic particles has been developed for the new fully automated, random access LIAISON immunoanalyzer. The LIAISON hCG assay is a two-site immunolouminometric one-step assay using two highly specific monoclonal antibodies. Total incubation time is only 10 min. A specially designed unique Reagent Integral contains all specific reagents; the on-board stability of these reagents is given over a very long period (> 4 weeks). The assay works with a 2-point calibrated master curve. 30 microliters sample is added to 200 microliters tracer and 20 microliters antibody-coated magnetic particles. After 10 min incubation the particles are separated, washed and the chemiluminescent signal is generated. The time to first result is only 15 min. The assay with a unique extended standard range up to 5,000 ng/ml shows no high dose hook effect up to 500,000 mlU/ml (spiked sera). The assay detects both the intact molecule and the free beta subunit. The cross-reactivity to FSH, LH and TSH is less than 0.1%. Precision (within-run < 3%; between-run < 5%), linearity, recovery and sensitivity (< 0.5 mlU/ml) are excellent. The assay shows a very good correlation to the LIA-mat hCG (r = 0.996). In summary the LIAISON hCG assay together with the new LIAISON immunoanalyzer is a very rapid and accurate method for the quantitative determination of hCG/beta-hCG in serum.

Comparison of visual microscopic and computer-automated fluorescence detection of rabies virus neutralizing antibodies

The rapid fluorescent focus inhibition test (RFFIT) and the fluorescent antibody virus neutralization test (FAVNT) are both diagnostic tests for determining levels of rabies neutralizing antibodies. An automated method for determining fluorescence has been implemented to reduce the work time required for fluorescent visual microscopic observations. The automated method offers several advantages over conventional visual observation, such as the ability to rapidly test many samples. The antibody titers obtained with automated techniques were similar to those obtained with both the RFFIT (n = 165, r = 0.93, P < 0.001) and the FAVNT (n = 52, r = 0.99, P < 0.001).

Liaison free PSA--an automated chemiluminescent immunoassay for the determination of free prostate specific antigen (fPSA)

The LIAISON fPSA offers a rapid, reliable and precise method for the fully automated determination of free PSA.

LIAISON Ferritin--an automated chemiluminescent immunoassay for the determination of Ferritin

An immunoassay utilizing chemiluminescence and paramagnetic particles has been developed for the new fully automated random access LIAISON immunoanalyzer. The LIAISON Ferritin assay is a two-site immunoluminometric one-step assay using two highly specific monoclonal antibodies. A specially designed unique Reagent Integral contains all specific reagents. The cooled reagent compartment guarantees an on-board stability of at least 4 weeks. The assay works with a 2-point calibrated master curve. To perform, the assay, 10 microliters sample is added to 300 microliters tracer and 20 microliters antibody-coated magnetic particles. After 10 min incubation the particles are separated, washed and the chemiluminescent signal is generated. The time to first result is only 15 min. The assay with a unique extended standard range up to 3,000 ng/ml shows no high dose hook effect up to 150,000 ng/ml (spiked sera). The cross-reactivity to human liver ferritin is 100%, to human spleen ferritin 66% and to human heart ferritin 8%. Precision (within-run < 3%; between-run < 5%), linearity, recovery and sensitivity (< 0.2 ng/ml) are excellent. The assay shows a very good correlation to LlA-mat Ferritin (r = 0.994). In summary the LIAISON Ferritin run on the new LIAISON immunoanalyzer and is a very rapid and accurate method rapidly providing reliable results.

Evaluation of Sysmex UF-100 urine flow cytometer vs chamber counting of supravitally stained specimens and conventional bacterial cultures

We evaluated the Sysmex UF-100 urine flow cytometer (TOA Medical Electronics, Kobe, Japan) with 269 uncentrifuged urine specimens by comparing it with Sternheimer staining and particle counting in 1-microL disposable chambers with both brightfield and phase-contrast microscopy (the reference method). Results of routine test strip analysis, sediment microscopy (182 specimens), and bacterial culture (204 specimens) were also available. Detection of urinary WBCs and RBCs was highly reliable with the UF-100 compared with manual chamber counting (r = .98 and .88, respectively). Identification of bacteria was equal to that with visual microscopy of uncentrifuged specimens; sensitivity was 55%, and specificity 90%, compared with bacterial cultures at a cutoff of > 10(3) colony-forming units per milliliter. Renal damage was difficult to evaluate even with manual methods because of the low counts of renal tubular cells and casts; with standard manual Sternheimer-stained sediment analysis, sensitivity was 65% to 69% and specificity 66% to 91%, compared with the uncentrifuged chamber method at a cutoff of 3 and 10 particles per microliter, respectively. Renal damage was demonstrated with the UF-100 with a sensitivity of 26% to 69% and specificity 92% to 94%, compared with chamber counts. Automated urinalysis with the UF-100 urine flow cytometer offers considerable savings in time and labor. When high sensitivity is needed, visual microscopic review should be performed to detect renal disease.

[Comparison of LDL-C values measured with the automated method and the ultracentrifugation method in severe hypertriglyceridemia, and prevalence and life-style of patients with hypertriglyceridemia]

The correlation between LDL-cholesterol (LDL-C) values assayed by the direct method and the ultra-centrifugation method is reported good in normal to moderate hypertriglyceridemia, but it is not clear in severe hypertriglyceridemia. We examined such a correlation in mild (triglycerides, 150-400 mg/dl; n = 3) and severe (> or = 800 mg/dl, n = 9) hypertriglyceridemia. The bias of LDL-C determined by the direct method in comparison with the ultracentrifugation method was from -1.1% to 3.4% and from -49.5% to 15.7% in mild and severe hypertriglyceridemia, respectively. The prevalence of severe hypertriglyceridemia was only 0.2% both in hospital patients and in company workers. Data analyses of company workers indicated that people with severe hypertriglyceridemia have a higher body-mass index, consume more alcohol, smoke more, and exercise less than those with a normal level of triglycerides. These results suggest that there is not a good correlation between LDL-C values assayed by the direct method and the ultracentrifugation method in severe hypertriglyceridemia; but that the direct method can be used for the clinical examination of LDL-C, because of the very low prevalence of severe hypertriglyceridemia. Patients with severe hypertriglyceridemia should improve their life-style as soon as possible.

Automated measurement of serum ferroxidase activity

A method is described for automated measurement of serum ceruloplasmin ferroxidase activity. In this method, Fe2+ ions are used as the substrate. In addition, a new calibration system without ceruloplasmin is also presented. Optimum assay reaction conditions were determined. Maximal catalytic activity was obtained at 0.45 mol/L acetate buffer, pH 5.8. The reagents and calibrator are stable for at least 6 months. Significant correlations between serum ferroxidase and p-phenylenediamine oxidase activities (r = 0.96; P <0.0001) and copper concentration (r = 0.93; P <0.0001) were found. The range for serum ceruloplasmin ferroxidase activity in healthy persons was 198-1107 U/L, and in patients with bronchial asthma it was 601-1912 U/L.