Rapid automated determination of adenosine deaminase and lysozyme for differentiating tuberculous and nontuberculous pleural effusions

The catalytic concentration of pleural adenosine deaminase (ADA) and the ratio of pleural lysozyme (PL) to serum lysozyme (SL) were measured in consecutive patients (49 tuberculous and 179 nontuberculous) with two automated procedures in a Hitachi 717 analyzer. Using sensitivity and specificity curves, we established cutoff values at 33 U/L for ADA and 1.7 for the PL/SL ratio. The sensitivity of ADA activities for tuberculous effusion was 90%, specificity 85%. Combining ADA with the PL/SL ratio enhanced specificity to 99%. However, high values for ADA and lysozyme ratios are not, alone or in combination, sensitive or specific enough to replace pleural biopsy or culture of pleural fluid for the diagnosis of tuberculous empyema.

Inorganic, organic, and total mercury in blood and urine: cold vapor analysis with automated flow injection sample delivery

A cold vapor atomic absorption technique for blood or urine mercury analysis that uses persulfate oxidation to prepare samples for total mercury analysis and acid permanganate oxidation to prepare samples for inorganic mercury analysis is described. The linearity of the procedures ranged from 0.5 to 25 micrograms/L. Precision ranged from 20% at 1 microgram/L to 7% at 20 micrograms/L. Documentation of accuracy is based on analysis of samples prepared by an international proficiency survey program. The development of a two-step digestion procedure followed by automated flow-injection mercury analysis was a necessary precursor to the assessment of inorganic and alkylmercury exposure in a large unexposed human population. Application of this technique to 902 blood and 902 urine samples collected from a normal human population who had no extraordinary mercury exposure generated mean plus two standard deviation skewed confidence-limit ranges of results as follows: blood total mercury, 0-8.4 micrograms/L; blood inorganic mercury, 0-1.7 micrograms/L; blood organic mercury, 0-7.5 micrograms/L; urine total mercury, 0-9.9 micrograms/L; urine inorganic mercury, 0-8.6 micrograms/L; and urine organic mercury, 0-1.8 micrograms/L.

D- and L-lactate determination in dairy products: presentation of a fast automated analysis system

A flow-injection system is presented, which is versatile, automated and has an integrated enzyme system. Its efficiency at determining D- and L-lactate separately in dairy products is compared with the officially used reference method (DIN 10335). By means of a mathematical elimination of matrix effects, the pretreatment steps can be clearly reduced. As a result of the immobilization of the enzymes, an appropriate automation software and an adaptation of the system developed to the given medium, the analysis could be performed within 5 min and was distinctly cheaper than alternative methods. The values determined in 15 different dairy products deviated from those of the reference method by 3% at a maximum.

Identification and cholesterol quantification of low density lipoprotein subclasses in young adults by VAP-II methodology

Low density lipoprotein (LDL) particles are heterogeneous in size, density, and chemical composition; small, dense LDL may be more atherogenic than large, buoyant LDL. We have developed a rapid microscale method called LDL VAP-II (Vertical Auto Profile-II) for quantification of cholesterol in LDL subclasses. The method is based upon a short (1 h) single vertical spin density-gradient ultracentrifugation and on-line VAP-II analyzer. LDL VAP-II is rapid and reproducible. Using this method five LDL subclasses, designated as LDL-1 (most buoyant) through LDL-5 (most dense), have been identified in a population consisting of 195 medical students (ages, 22-29 years). The Rf (relative position of the major LDL peak in the density gradient; the higher the Rf value, the lower the peak density) was significantly positively correlated with cholesterol levels of high density lipoprotein (HDL) (r = 0.594), HDL3 (0.350) and HDL2 (0.625), and significantly negatively correlated with triglycerides (TG) (-0.355) and cholesterol levels of very low density lipoprotein (VLDL) (-0.386) and intermediate density lipoprotein (IDL) (-0.432). These results are consistent with those obtained by other investigators. The Rf value was significantly correlated with peak particle diameter as determined by non-denaturing gradient gel electrophoresis (r = 0.859). In a forward stepwise multivariate analysis comparing Rf with sex, VLDL, LDL, Lp[a], IDL, HDL3, HDL2, and triglyceride, only HDL2 remained in the model.

A linear modelling approach to automatic interpretation of quality control measurements in mammography

An approach to the automated interpretation of quality control data is described in which the relationship between small changes in system performance and the resulting small changes in the measured quality control test results are approximated as a set of linear equations in matrix form. The inverse of this forward matrix is then used to identify causal changes from the set of measured changes. This approach has been investigated for the case of mammographic screening quality assurance and shown to provide a potentially useful tool to assist in the interpretation task.

Decoupling spatial and temporal processes for clinical analyzers

The separation of time and space in processing a sample greatly simplifies the design of automation for clinical testing. The efficient spatial arrangement of analytical units and sample manipulators has become a more complex task because of the degree of automation required on today's state-of-the-art analyzer. Minimization of sample volume and the reduction of overall analyzer size further complicate the design problem. We report the development of a proprietary method of decoupling the temporal and spatial elements required for analysis of samples. This process is based on number theory and can be used to optimize the distance between the physical processing stations while allowing these same stations to operate on samples over a substantial range of times. The technique is versatile and can also be used when it is desirable to sequentially move groups of items from location to location.

Automated determination of microbial peroxidase activity in fermentation samples using hydrogen peroxide as the substrate and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonate) as the electron donor in a flow injection system

An automated flow injection method has been developed for the determination of microbial peroxidase activity. The substrate used was hydrogen peroxide and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonate (ABTS) was used as the electron donor. In the presence of hydrogen peroxide, peroxidase catalyses the dehydrogenation of ABTS, resulting in the formation of a resonance-stabilized radical cation of ABTS. The green-blue colour formed, recorded at 418 nm, is taken as a measure of the peroxidase activity. The general technical conditions and the general enzymic kinetics have been optimized. Conditions for activation and stabilization of the enzyme were found, e.g., ammonium sulfate acts as a peroxidase activator. The resulting method has a good precision, sensitivity and speed.

Fully automated assay for cobalamin-dependent methylmalonyl CoA mutase

We constructed a fully automated assay for the cobalamin-dependent enzyme methylmalonyl coenzyme A (CoA) mutase. The assay involves preincubation of the enzyme with adenosylcobalamin, incubation with substrate, termination of the reaction by adding trichloroacetic acid, filtration to remove precipitated protein, and finally analysis of the filtrate (containing methylmalonyl CoA and the product succinyl CoA) by HPLC. These steps were carried out by an inexpensive programmable autosampler equipped with thermostated sample racks and mobile disposable extraction column racks used here as a sample filtering device. A central element in the developmental work was to measure stability of reagents, enzyme, and product against the storage conditions during unattended analysis and the time table of the program. We evaluated the performance of the method by measuring methylmalonyl CoA mutase activity in rat liver, human fibroblasts, and human glioma cells. The within-run imprecisions (CV) were 2-10% for measuring enzyme activity in 20 replicate samples of a homogenate (test of the automated assay), and 7-12% for measuring enzyme activity in homogenates from 20 culture dishes (test of the total procedure). The method allows the unattended analysis of 56 samples per 24 h. This strategy for automation may be easily adapted for other enzyme assays.

Rapid, fully automated measurement of plasma homocyst(e)ine with the Abbott IMx analyzer

We have developed a totally automated fluorescence polarization immunoassay for homocyst(e)ine with no pretreatment or chromatographic steps. Comparison with four well-established chromatographic methods yielded r values ranging from 0.980 to 0.997 and slopes from 1.030 to 1.493. Inter- and intraassay CVs ranged from 0.0% to 8.0% and from 0.0% to 6.4%, respectively. Imprecision (CV) of measuring six plasma samples on three instruments ranged from 6.3% to 10.2%. The assay was linear for plasma samples diluted with buffer from 0 to 8-fold. Mean recovery of homocysteine added to two plasma samples was 97.1% and 99.9%. The assay exhibited almost no cross-reactivity towards cysteine and methionine, and a batch of 20 samples can be processed in 60 min.

Automated analysis of a novel anti-epileptic compound, CGP 33,101, and its metabolite, CGP 47,292, in body fluids by high-performance liquid chromatography and liquid-solid extraction

Automated procedures for the determination of CGP 33,101 in plasma and the simultaneous determination of CGP 33,101 and its carboxylic acid metabolite, CGP 47,292, in urine are described. Plasma was diluted with water and urine with a pH 2 buffer prior to extraction. The compounds were automatically extracted on reversed-phase extraction columns and injected onto an HPLC system by the automatic sample preparation with extraction columns (ASPEC) automate. A Superlosil LC-18 (5 microns) column was used for chromatography. The mobile phase was a mixture of an aqueous solution of potassium dihydrogen phosphate, acetonitrile and methanol for the assay in plasma, and of an aqueous solution of tetrabutylammonium hydrogen sulfate, tripotassium phosphate and phosphoric acid and of acetonitrile for the assay in urine. The compounds were detected at 230 nm. The limit of quantitation was 0.11 mumol/l (25 ng/ml) for the assay of CGP 33,101 in plasma, 11 mumol/l (2.5 micrograms/ml) for its assay in urine and 21 mumol/l (5 micrograms/ml) for the assay of CGP 47,292 in urine.

Automated dibucaine number measurement with DuPont Dimension ES and AR analyzers

We report a fully automated method for determining dibucaine number (DN) in a single-run procedure involving Dimension cholinesterase (CHE) Flex pseudo-(P)CHE reagents. The method was developed and optimized with the "open channels" and "kinetic" software facilities of the Dimension-ES instrument, where the DN is calculated automatically by an algorithm from the ratio of the uninhibited and inhibited rates, measured bichromatically, from a single analysis. The protocol was satisfactorily assessed for substrate depletion, linearity, reagent stability. and the effects of different dibucaine concentrations. Validation was performed across a range of CHE activities (1.5-22 kU/L) representing the three main genotypes, UU, UA, and AA. The respective DNs (mean +/- SD), determined on the Dimension-ES, were 82.0 +/- 1.6 (n = 32), 71.0 +/- 3.1 (n = 10), and 23.0 +/- 2.7 (n = 14), with corresponding imprecisions (CV) of 0.3%, 0.6%, and 5.2% (intraassay) and 0.7%, 0.7%, and 8.6% (interassay). Comparisons with reference (x) laboratory values and the DuPont aca (x') procedure (n = 53) gave regression equations of: y = 0.88x + 11.2, r = 0.99, and y = 0.85x' + 11.9, r = 0.99. A separate trial conducted with a Dimension-AR instrument gave similar performances. We conclude that the new DN method is fast, efficient, and appropriate for clinical use.

Automated measurement of alpha-amylase isoenzymes with 6(3)-deoxymaltotriose as selective amylase inhibitor

We developed an automated method for measurement of alpha-amylase isoenzymes in serum by a single kinetic assay (SKA) and a double kinetic assay (DKA) with 2-chloro-4-nitrophenyl-6(5)-azido-6(5)-deoxy-beta-maltopentaoside as a substrate and 6(3)-deoxymaltotriose (DOG3) as a novel selective amylase inhibitor. DOG3 showed a large difference in inhibitory activity between human pancreatic alpha-amylase (HPA; 86.9% inhibition) and salivary alpha-amylase (32.1% inhibition) at 0.33 mmol/L. Constant inhibition was obtained immediately after addition of DOG3. The inhibitory effect did not change with variation in concentrations of amylase up to approximately 3000 U/L. The results obtained by SKA correlated well with those obtained by three methods: monoclonal antibody (r = 0.988), wheat germ inhibitor (r = 0.989), and DKA (r = 0.995). The within-run and between-run CVs for HPA were 0.63-2.32% on SKA, 0.69-1.81% on DKA. No significant interferences by endogenous serum compounds were observed with the proposed methods.

Automated measurement of urinary iodine with use of ultraviolet irradiation

We have modified an automated measurement system of urinary iodine (UI) and established a sensitive UI assay system by using ultraviolet (UV) digestion. The automated system is sensitive enough to detect concentrations of UI < 0.78 mumol/L (< 10 micrograms/dL) in a small volume of urine (500 microL). Sample throughput is > 30/h, including a water washing. The within-assay imprecision (CV) was < or = 10% in the UI range of 0.10-3.00 mumol/L; the between-assay CV was usually < or = 15% in the same range. Analytical recovery of iodine added to urine samples was consistently > 90%. The theoretical values were recovered when UV irradiation was used but not in its absence. High (supraphysiological) doses of thiocyanate or ascorbic acid, which are major interfering substances to the ceric-arsenious acid reaction, did not interfere with this system. The correlation between UI determined by this method and by the acid digestion method was linear (r = 0.994). For samples containing iodine at < 1.00 mumol/L, the correlation between values by both methods was still significant (r = 0.937). UI in an iodine-deficient area in Ukraine, measured by this system, ranged from 0.06 to 1.83 mumol/L (median 0.44 mumol/L, n = 95), significantly lower than in Japan (range 0.23-50.70 mumol/L, median 4.70 mumol/L, n = 84) and consistent with mild iodine deficiency. This modified automated assay system, therefore, is useful and applicable for screening UI in inhabitants of iodine-deficient areas.

Automated homogeneous liposome-based assay system for total complement activity

We developed an automated homogeneous immunoassay, based on immune lysis of dinitrophenyl (DNP)-labeled liposomes, for measuring total complement activity. Liposome lysis caused by complement activity was detected spectrophotometrically from entrapped glucose-6-phosphate dehydrogenase activity. Complement activity in human sera was quantified by comparison with a calibration curve. For ease of application to fully automated routine clinical analyzers, we adopted a two-reagent system, one reagent containing a homogeneous population of small DNP-labeled liposomes and one containing antibody/substrate. This system required calibration only once a week. Within-run and between-run CVs were 0.4-1.3% (n = 10) and 1.8-4.7% (n = 10), respectively. Serum results were linear upon dilution (with saline) over a twofold range. Bilirubin, hemoglobin, Intrafat, and serum proteins such as rheumatoid factor, M protein, IgG, and IgA did not affect the assay results. The results (y) correlated well with those from a hemolytic complement activity test (x): y = 1.05x - 1.14, r = 0.92, on 66 samples in the range < 10- > 50 kU/L. This method should therefore be of great use for the determination of complement activity.

Density adjustment of software settings minimizes bias in automated sperm motility estimation

To minimize overestimation of motility, it is recommended that fresh semen be diluted with seminal plasma prior to automated analysis. However, for glycerolated or cryopreserved semen this is impractical, and alternative methods are needed to minimize automated motility bias. In the present study, the proportion of motile spermatozoa was determined in fresh, diluted and cryopreserved semen (n = 25 ejaculates) using visual and automated methods. The effect of software settings on motility was investigated by assessing samples at a range of modified settings. At standard settings, automated motility was biased in fresh semen (+7.2%) after dilution with cryopreservative (-2.9%) and after cryopreservation (-7.8%) (P < 0.0001 versus visual). Automated motility was inversely related to the minimum number of frames for motility sampling (P < 0.0001), with mean estimates of 41.0, 46.1, 52.0 and 58.2% generated at settings of 8, 4, 2 and 1 frame(s) respectively (n = 15 fresh, diluted and cryopreserved samples). Based on an arbitrary ordinal scale, a method was developed whereby motility sampling was adjusted prior to analysis according to sperm density. Analysis of an independent set of semen samples with density-adjusted software settings reduced bias in automated estimates (n = 30) before and after freezing (P < 0.0001). In addition, bias was no longer related to sperm density. In conclusion, modification of software settings is an effective alternative to dilution to minimize bias in automated motility estimates in fresh, diluted and cryopreserved human semen.

Use of standardized protease enzymes for antibody screening of blood donor samples with the microplate system AutoAnalyzer

Papain, bromelin and ficin can be standardized by the casein method for use in red blood cell antibody screening tests. The minimal and optimal enzyme activity for detecting blood group antibodies in donors, using the new Automated Pre-Transfusion Blood Testing System Olympus PK7200 by the two-stage method for all three enzymes, is one casein unit. One casein unit of proteinase activity changed the red blood cell surface charge to a low plateau value as measured by electrophoretic mobility and sialic acid content, and removed sterically inhibiting structures of surface protein as detected by SDS-PAGE.

Three assays for glycohemoglobin compared

Using 123 specimens, we compared the concordance of three different methods for determining glycohemoglobin (GHb): the Diamat (Bio-Rad Laboratories), an automated analyzer measuring HbA1c by cation-exchange chromatography; an assay with the IMx analyzer (Abbott Laboratories), based on boronate affinity binding; and an HPLC method measuring HbA1c by cation-exchange chromatography on a PolyCAT A column (PolyLC Inc.). The Pearson's correlation coefficient between PolyCAT A and Diamat was 0.900 +/- 0.038 (mean +/- 2 SD) and between PolyCAT A and IMx, 0.857 +/- 0.042. However, up to twofold differences were seen in some samples. The proportion of GHb was consistently lower with the PolyCAT A method than with the other two assays, apparently because of better separation of HbA1c from nonglycated coeluting forms of Hb. The difference in glycation percentage between the PolyCAT A and Diamat methods is 2-3% over the whole concentration range. These results point to the limitations of Diamat as a reference method to be used to calibrate other methods for determining HbA1c. Further, a switch from one method to another is likely to cause considerable problems in the clinical follow-up of certain patients.

[Irregular antibodies. A comparative study of 2 series of 20,000 subjects: one with a conventional identification test, the other with gel-test]

The results of irregular antibody screening in two successive series of 21485 and 19819 individuals were retrospectively analysed. All the irregular antibody screenings were performed with an autoanalyser according to Rosenfield and Lalezary [1, 2] but red cell antibody identification tests were not the same: conventional manual tests in the first series and gel-test Diamed in the second one. In spite of a bigger number of identification tests performed in the second series, the percentage of patients with irregular antibodies was approximately the same (2.27% and 2.22%) in each series. Analysis of identified specificities shows in the second series the increase of immune antibodies (+ 42.3%) especially antibodies with anti-Rh specificity and the decline of natural antibodies (- 28.9%) essentially of anti-Lewis b and P1 antibodies. The sensitivity of both the gel-test and the autoanalyser screening for identification of immune antibodies are more or less the same. The sensitivity of gel-test probably gives a safer transfusion but increases the workload of both the laboratory and the blood bank delivery service.

Automated procedures for the quantitation of protein

An entirely automated 96-well microplate-based system to perform procedures for the measurement of protein is described. This single instrument system utilizes a series of computer-controlled mechanical subsystems to move the plate, control incubations and dispense samples or reagents in order to perform the assay. This system allows the investigator to reproducibly perform these protein assays on large numbers of biological samples with minimal effort.

Fully enzymatic method for determining 1,5-anhydro-D-glucitol in serum

We have developed a fully enzymatic method to measure 1,5 anhydro-D-glucitol (1,5-AG) in serum through use of pyranose oxidase (PROD: EC 1.1.3.10), glucokinase (EC 2.7.1.2), and an ATP-regenerating system. In a previous report (Clin Chem 1989;35:2039-43) the glucose interfering with the measurement of 1,5-AG was removed with a minicolumn. In the method used here, glucokinase and an ATP-regenerating system efficiently convert glucose to the unreactive compound, glucose 6-phosphate, making the method selective for 1,5-AG. The hydrogen peroxide produced in the oxidation of 1,5-AG by PROD is detected with a standard enzymatic color-developing system. The within-run and day-to-day precision (CV) of this method was 0.52-1.29% and 1.17-4.48%, respectively. The correlation (r) between the results obtained with our proposed method (y) and those obtained with the mini-column method (x) was 0.998 (y = 1.007x + 0.493 mg/L; n = 100; Sy/x = 0.641 mg/L). This newly developed method allows quicker and easier measurement of serum 1,5-AG than previously described methods.

Fully automated flow-injection system for quantifying 1,5-anhydro-D-glucitol in serum

We have developed a flow-injection system with colorimetric detection to measure 1,5-anhydro-D-glucitol in serum. Serum samples are directly and serially injected into a clean-up column every 3.5 min to remove interferences before the enzymatic reaction. 1,5-Anhydro-D-glucitol, after being passed through the column, is oxidized by immobilized pyranose oxidase (EC 1.1.3.10), and the hydrogen peroxide produced reacts with the chromogen substrate in the presence of immobilized horseradish peroxidase (EC 1.11.1.7) to form Bindshedler's Green. The detection limit was 1.2 mumol/L (1.2 pmol). The correlation between results obtained with the present system (y) and gas chromatography-mass spectrometry (GC-MS) (x) in samples containing < 30 mumol/L 1,5-anhydro-D-glucitol, including many samples from patients with diabetes mellitus, was y = 0.975x-0.111 mumol/L (r = 0.997), which was superior to that obtained between the enzymatic and GC-MS methods. Our system needs only to be set up; it runs without any manual pretreatment, assays 17 samples/h, and shows imprecision (CV) of < 2%.

[Basic evaluation of the new fully automated urine sediment analyzer (U-FCM) based on flowcytometric technology]

We developed a new automated urine sediment analyzer (U-FCM) based on Flow Cytometry with the cooperative technical aid of TOA Medical Electronics Co., ltd. Flow Cytometry using an argon laser (wave length 488 nm) is used as the method for detection. This instrument provides quick, easy and accurate screening for patients whose urinalysis abnormalities indicate the need for further testing. Abnormal patient samples are separated from patient samples whose parameters are totally normal, thus decreasing the need for additional testing. The instrument is useful as a diagnostic aid, and in monitoring the therapeutic effect. Also it is useful in the health checking service for visitors at the AMHTS office.

EMIT cyclosporine assay: development of an application protocol for Technicon AXON System

Monitoring parent drug cyclosporine (CsA) concentrations in whole blood has been facilitated by the introduction of automated nonisotopic immunoassays [fluorescence polarization monoclonal whole blood assay (FPIA), EMIT Cyclosporine Assay]. The latter assay currently has a defined application only for Cobas Mira Chemistry Systems. The purpose of our work was to develop an application for this assay on the Technicon AXON. Instrument settings were optimized to arrive at the following assay performance characteristics. Limit of sensitivity was 50 micrograms/L. Interassay coefficients of variation (CV) were 11.2% (n = 16; mean = 81 micrograms/L) and 9.4% (n = 16; mean = 418 micrograms/L). Recoveries of 102, 112, and 117% were obtained by spiking aliquots of 10 whole blood patient pools of known CsA concentrations with 50, 100, and 200 micrograms/L CsA, respectively. Serial dilutions of two patient specimens demonstrated a linear relationship between expected and actual CsA concentrations (r = 0.996, 0.998; regression lines; y = 0.989x + 11.7; y = 0.979x + 9.5). Carryover and interference (lipemia) were not evident. Instrument calibration stability is at least 1 month. Comparison with CsA concentrations analyzed in renal transplant patients by the FPIA assay produced a linear regression equation of EMIT = 1.113x - 44.5, r = 0.968, Sy/x = 20.8, n = 32. Comparison with high-performance liquid chromatography (HPLC)-derived values in the same patient population produced a linear regression equation of EMIT = 1.114x - 16.4, r = 0.970, Sy/x = 20.2. FPIA-derived CsA concentrations averaged 14.2% more than those obtained with the EMIT method with the latter averaging 1.3% more than HPLC values.(ABSTRACT TRUNCATED AT 250 WORDS)

Automated Cobas Mira kinetic enzymatic assay for ethylene glycol applied to emergency situations

An automated kinetic method for assaying ethylene glycol in serum using glycerol dehydrogenase with the multiparametric analyzer Cobas Mira is described. Initially, 5 microL of sample is mixed with tris-NAD buffer; after enzyme addition, the variation of the absorbance at 340 nm is automatically measured, and the instrument calculates the ethylene glycol concentration of the specimen. The method has good precision and specificity and is suitable for emergency screening. Some applications developed in our laboratory are also described.

Hybridisation techniques on gridded high density DNA and in situ colony filters based on fluorescence detection

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Simple procedures can markedly enhance automated immunoassay performance

Theoretically, optimal performance for an immunoassay system is achieved when both the interassay and within-run precisions are identical. Using the Ciba Corning ACS:180 automated immunoassay system, the authors made two simple changes to the operating procedures that allowed near-optimal analytic performance (as assessed with the interassay coefficient of variation determined by the protocol of the National Committee for Clinical Laboratory Standards) for four of six hormones: thyroid-stimulating hormone, luteinizing hormone, prolactin, and human chorionic gonadotropin. At low hormone concentrations, the 20% interassay coefficients of variation for the hormones assayed were as follows: free tetraiodothyronine, 1.74 pM; thyroid-stimulating hormone, .033 mIU/L; luteinizing hormone, .21 U/L; follicle-stimulating hormone, .69 U/L; prolactin, 5.03 mU/L; and human chorionic gonadotropin, 1.52 mU/L. The operational enhancements improved the analytic performance of the assay for all hormones assessed compared with the performance of previously used isotopic immunoassays.

Rapid automated enzyme immunoassay of serum amyloid A

Serum amyloid A (SAA), a sensitive acute-phase protein, is the precursor of AA fibrils in reactive amyloidosis. However, SAA is poorly immunogenic, and development and standardization of immunoassays of this protein have been difficult. We established an automated polyclonal/monoclonal microparticle capture enzyme immunoassay, standardized with the World Health Organization prospective reference standard for SAA. A stabilized concentrate of SAA was used for controls and calibrators. The assay range was 1-750 mg/L with CVs < 7% throughout. Plasma and serum gave identical results and no interferences were observed. Linear regression against radial immunodiffusion assay gave a slope of 1.04 (95% confidence interval 0.99-1.10), intercept of -9 mg/L (95% confidence interval -14-3), and residual SD (SEE) of 20 for samples containing < or = 200 mg/L (n = 173). In 105 apparently healthy adults the mean (SD) SAA concentration was 3.7 (3.6) mg/L, the median was 3.0 mg/L, and the range, 0.7-26.4 mg/L. In clinical acute-phase sera, values up to 2200 mg/L were seen. This method will facilitate measurement and investigation of SAA in clinical practice generally and in AA amyloidosis.

Automation of the Maxam-Gilbert chemical sequencing reactions

A practical automated method of Maxam-Gilbert chemical sequencing reactions that uses solid-phase chromatography methods to purify DNA following chemical modification and cleavage is described in this report. The automation has primarily been made possible by using specially designed BioPak mini-columns, compatible with the Biomek 1000 automated workstation, which can be utilized in a manner similar to that of standard pipet tips. This automated chromatographic sequencing method produces rapid and reliable data as verified by sequencing a known human factor IX exon VIII gene fragment. The procedure presented in this report is a prototype for a single-fragment reaction and can easily be expanded to perform reactions on as many as 8 fragments at a time. The automation eliminates the tedious and time-consuming steps in the original method and increases the rate of sequence acquisition. This technology makes the Maxam-Gilbert chemical sequencing protocol more accessible, especially in large-scale, automated sequencing projects.

[Evaluation of yellow IRIS/model 450 for routine urinalysis]

BACKGROUND

Urinalysis yields a great deal of information quickly and economically for detection of renal diseases. The inter-technician variation and time consuming are major problems while processing large amount of specimens. The purpose of this study is to evaluate the benefit of an automated urine analyzer, Yellow IRIS/model 450, and the feasibility of replacing the currently-used manual KOVA method.

METHODS

A total of 1,000 random urine specimens were analyzed with Yellow IRIS and KOVA method. Precision, correlation, and detection rate of abnormality were compared between these two methods.

RESULTS

The results revealed that Yellow IRIS had high precision with little between-run and within-run variation, while the obtained values were notably highly correlated with the expected values (r = 0.99). In addition, detection rate of blood cell abnormalities for the Yellow IRIS was twice better than for the manual KOVA method.

CONCLUSIONS

The high precision of the machine, the simple procedure of performing, and the quickness of obtaining data, can minimize variability caused by the manual method and save processing time for mass screening. It is feasible to replace the manual urinalysis by the automated urine analyzer Yellow IRIS. Nevertheless, to minimize the extent of manual manipulation, including pouring the urine into the pour cup, and placement of the urine strip, will assist in a wider acceptance for the Yellow IRIS/Model 450.

Evaluation of an algorithm for the automated sequential assignment of protein backbone resonances: a demonstration of the connectivity tracing assignment tools (CONTRAST) software package

The peptide sequential assignment algorithm presented here was implemented as a macro within the CONnectivity TRacing ASsignment Tools (CONTRAST) computer software package. The algorithm provides a semi- or fully automated global means of sequentially assigning the NMR backbone resonances of proteins. The program's performance is demonstrated here by its analysis of realistic computer-generated data for IIIGlc, a 168-residue signal-transducing protein of Escherichia coli [Pelton et al. (1991) Biochemistry, 30, 10043-10057]. Missing experimental data (19 resonances) were generated so that a complete assignment set could be tested. The algorithm produces sequential assignments from appropriate peak lists of nD NMR data. It quantifies the ambiguity of each assignment and provides ranked alternatives. A 'best first' approach, in which high-scoring local assignments are made before and in preference to lower scoring assignments, is shown to be superior (in terms of the current set of CONTRAST scoring routines) to approaches such as simulated annealing that seek to maximize the combined scores of the individual assignments. The robustness of the algorithm was tested by evaluating the effects of imposed frequency imprecision (scatter), added false signals (noise), missing peaks (incomplete data), and variation in user-defined tolerances on the performance of the algorithm.

Reloading and stability of polyacrylamide slab gels for automated DNA sequencing

Current automated fluorescent instruments are all based on slab gels that are used once and then discarded. Practitioners of capillary gel electrophoresis often reuse their gels for multiple samples. As slab gels are made thinner to increase speed, the ability to reload new samples after each run will become more desirable. Techniques have previously been developed for reloading and stabilizing capillary gels. The application of these methods to slab gel electrophoresis is reported. Gels are shown to be reusable for at least four consecutive automated runs. The stability of various slab gel formulations and their ability to survive multiple loadings with sequencing samples are compared. Formamide-containing gels are shown to be superior to their urea counterparts. The potential that running buffer additives have for improving automated DNA sequencing is discussed. Residual template DNA in sequencing samples can produce gel instability, reduce resolution and decrease signal. These effects are examined.

Sequential quantification of AgNOR area and number during silver staining by means of an image analysing system

Standardized AgNOR staining protocols are required to compare results obtained by means of image analysis systems (IAS) in different laboratories. In order to investigate the staining kinetics of the NOR silver staining, we evaluated automatically the area and number of AgNORs of a human transitional-cell carcinoma cell line (HOK-1) by IAS at one minute intervals over a total staining period of 30 minutes. Results showed a constant increase (standard error of estimate: 0.001; R squared: 0.8) of the AgNOR area reaching a plateau after 10 minutes followed by further area increase. In contrast, in all experiments a pronounced variability in the AgNOR number (standard error of estimate: 0.042; R squared: 0.75) was noted, reflecting the aggregation of silver stained spots. Thus the evaluation of the AgNOR area yielded reliable and easily reproducible results, whereas the assessment of the AgNOR number by means of an automated IAS was associated with a marked variability.

Automated gas chromatography/tandem mass spectrometry assay for tebufelone and a 13C,(18)O-labeled analog in plasma: applicabilityto absolute bioavailability determination

An automated capillary gas chromatography/tandem mass spectrometry (GC/MS/MS) assay for the simultaneous quantitation of tebufelone (TE) and 13C, (18)O-labeled TE (TE-CO) in plasma was developed. This method permits the use of stable isotope coadministration (TE and TE-CO dosed concurrently via peroral and intravenous routes, respectively) for the determination of TE absolute bioavailability. The selectivity of MS/MS conducted on a triple-quadrupole instrument allowed minimal sample preparation and rapid analysis. Electron ionization produced molecular ions (M+) for TE, TE-CO, and the 3-methyl-TE internal standard which were selected in Q1 to undergo collisionally activated dissociation in Q2. Quantitation was achieved through monitoring product ions at m/z 248, 251 and 248, respectively, in Q3. A 2-1000 ng per sample (40 pg to 20 ng injected) quantitation range provided access to an effective 1-5000 p.p.b. plasma concentration range (0.2-2 g samples) for both TE and TE-CO. The assay showed no bias and less than 8% relative standard deviation over the entire range. The method was used to determine plasma levels of TE and TE-CO in four dogs receiving 2.5:2.5 mg/kg TE:TE-CO, intravenously. The pharmacokinetics of both isotopomers proved to be identical, indicating no isotope effect and verifying the chemical stability of the (18)O-carbonyl label under these dosing conditions. In addition, the applicability of this analytical approach to the determination of TE peroral bioavailability was initially tested in dogs.

Measurement of hybridoma cell number, viability, and morphology using fully automated image analysis

A novel automated image analysis method is described for characterizing the viability and morphology of animal cells from suspension cultures. With the aid of the exclusion dye Trypan Blue, the total and viable cell counts and the percentage of dead cells present are found. The area, perimeter, equivalent diameter, and circularity of the projected image of each cell are also measured, allowing the estimation of cell volume. The image analysis method is inherently sensitive, precise, consistent (non-operator dependent) and relatively fast, taking approximately 22 min to analyze one sample. The data it gives on individual cellular activity, as characterized by Trypan Blue uptake and cell morphology, are valuable in allowing early diagnosis of even subtle changes in the health of a culture. The method should permit better optimization of culture conditions, and will provide data for the modeling of cell population dynamics. As the conventional manual method is operator dependent, relatively limited in the amount of information it provides, and has a tendency to underestimate Trypan Blue takeup, it is suggested that image analysis be the preferred option for animal cell counting and viability determinations.

[The development of a rapid semiautomatic enzymatic analyzer of beta-lactam antibiotics]

A new method and a device for enzymatic express assay of beta-lactam antibiotics are described. The principle of the device operation is based on the use of native enzymes specific to the antibiotics assayed. The method makes it possible to exclude the influence of the buffer capacity of the samples on the results of the assay. The data on the testing of the method and device with model solutions of benzylpenicillin are presented. The relative error of a single measurement does not exceed 2 per cent. The time of an assay is not more than 3 minutes. Recommendations on the use of the device in research studies and manufacture are presented.

Amino acid sequence of a major human amelogenin protein employing Edman degradation and cDNA sequencing

The abundant hydrophobic, proline-glutamine, and histidine-rich (over 90%) amelogenins constitute the major class of proteins in forming extracellular enamel matrix. These are thought to play a major role in the structural organization and mineralization of developing enamel. The present report describes the successful sequencing of the major human amelogenin protein, by use of both Edman degradation and cDNA sequencing. When Edman degradation was used, over 75% of the primary structure of the protein was determined. This sequence was supplemented with cDNA sequencing studies, which revealed the predicted sequence of this protein. Together, they provide the complete sequence of an important human enamel protein. The information complements recent studies on bovine and human amelogenin genes. A comparison between the present results and the protein sequences predicted from the corresponding human amelogenin genomic coding regions and that of cDNA sequences of other species is described.

Automated immunochemical binding assay (flow-ELISA) based on repeated use of an antibody column placed in a flow-injection system

A computer-controlled immunological binding assay intended for monitoring concentrations of interesting metabolites during bioprocesses has been developed. The main focus has been on speed, reliability, reproducibility and operational stability of the assay. The assay is based on the repeated use of a preparation of immobilized antibodies. Stability in the regeneration step is a prerequisite and was achieved by intermittent recalibration of the system. Furthermore, before immobilizing the polyclonal antibodies, they were purified on immobilized antigen and eluted using the same procedure as used in the assay cycle. Antibody preparation could be used for more than 50 cycles and in some cases for several hundred cycles. Since the calibration curve is valid for the whole life-time of the antibody column, recalibration only involved the registration of the column capacity. Experiments have been performed concerning monitoring of chromatographic separations as well as adsorption experiments from complex mixtures.

Automated determination of free phenytoin in human plasma with on-line equilibrium dialysis and column-switching high-performance liquid chromatography

Free phenytoin in human plasma was automatically determined by on-line equilibrium dialysis using the automated sequential trace enrichment of dialysate (ASTED) sample preparation system and HPLC. The dialysis cell was a modification of the cell supplied with the ASTED. Total phenytoin was analysed with the same analytical set-up and plasma protein binding was determined. Free phenytoin was determined in plasma from epileptic patients and the results were compared to those obtained by ultrafiltration. Automated determination of free and total phenytoin in plasma by the ASTED-HPLC combination was shown to be an accurate and reproducible method and the results in free phenytoin analyses were in agreement with those found with ultrafiltration. The sample throughput with the automated on-line combination of dialysis and column-switching HPLC was 75 samples in 24 h when the sample was dialysed at 37 degrees C.

Automated enzymatic analysis of inulin

We have developed an automated enzymatic assay for quantitation of inulin in plasma and urine that can be performed on the Cobas FARA II. In the assay, inulinase hydrolyzes inulin to fructose, and sorbitol dehydrogenase converts fructose to sorbitol with consumption of NADH, which is detected by spectrophotometry. The method incorporates a sample blank (inactivated inulinase) for each specimen to subtract contributions of endogenous fructose. Recovery of fructose or inulin was near 100%, with linearity to 300 mg/L. The enzymatic assay (y) agreed well with an anthrone comparison method (x) for analysis of inulin in both urine specimens (y = 1.00x - 138; Sy/x = 714) and plasma specimens (y = 1.00x - 3.5; Sy/x = 5.5). Glucose at 300 mg/L yielded an apparent inulin value of 1.3 mg/L in the enzymatic assay, but reacted at nearly 10% equivalency in the anthrone assay. Interferences from sorbitol, mannitol, and xylitol were negligible. CVs for day-to-day precision studies were 1-4%. The automated enzymatic assay of inulin is faster and avoids the use of caustic reagents required by the classical anthrone method.

Fully automated assay of glycohemoglobin with the Abbott IMx analyzer: novel approaches for separation and detection

We describe a novel assay for measuring glycohemoglobin directly from anticoagulated whole blood with the Abbott IMx analyzer. The glycohemoglobin is labeled with a soluble polyanionic affinity reagent and the anionic complex is then captured with a cationic solid-phase matrix. Glycohemoglobin is quantified by measuring the quenching by heme of the static fluorescence from an added fluorophore. The assay is standardized to report both percent total glycohemoglobin (%GHb) and percent hemoglobin A1c (%HbA1c). Glucose, bilirubin, triglycerides, labile fraction, and hemoglobin variants do not interfere in the assay. Within- and between-run CVs are approximately 4-5%, with total CVs of approximately 6.5%. Highly significant linear correlations (r > 0.97) were obtained in comparison studies with two major assay methodologies. The time to obtain one result is approximately 10 min (including assay of a control), 56 min for 22 results. We describe the development, standardization, and validation of this new method.

A micro enzymic method for determination of choline-containing phospholipids in serum and high density lipoproteins

A micro method is described for the assay of choline-containing phospholipids in serum and high density lipoproteins (HDL) using an automated microtiter plate reader. The method is adapted from the enzymic method of Takayama, Itoh, Nagasaki, and Tanimuzu (Clin. Chim. Acta 79, 93-98, 1977) using phospholipase D, choline oxidase, and peroxidase coupled with the color generating system phenol and 4-amino-antipyrine. The micro method requires 5 microL of serum or HDL sample, and 42 samples can be assayed in duplicate in one run using a 96-well flat-bottom microtiter plate. The reaction is linear up to 400 mg/dL and the lower limit of detection is 0.25 mg of choline-containing phospholipids per assay. The coefficient of variation within an assay is 0.86-0.79%, and day-to-day variation is 0.9-1.5%. Results obtained by the micro method are in excellent agreement with those obtained by the procedure of Takayama et al. (r = 0.997). The supernatant left after removal of low density lipoproteins and very low density lipoproteins from serum and precipitation with heparin/manganese chloride reagent can thus be conveniently used for the micro assay of choline phospholipids in HDL.

An automatic monitoring system for epithelial cell height

This paper describes an automatic method to measure cell height (h) of epithelia grown as monolayers on transparent filter supports. Tissues are mounted in an Ussing-type chamber enabling solution exchange on both sides. The apical and basal side of the epithelial cells are marked with fluorescent beads. The image of the fluospheres is captured with a video camera and processed by a computer-based video imaging system. One basal reference bead in a gelatin layer on the filter support and up to three beads attached at the apical surface are used to monitor changes in cell height of three cells simultaneously. The focusing of the microbeads is done automatically by moving the objective with a piezoelectric device mounted on the nosepiece of the microscope. The algorithm for locating the bead is based on the changes in fluorescent light intensity emitted by the fluospheres. The method has an accuracy higher than 0.1 micron and a time resolution as low as 6 s if measurements are restricted to one bead at the apical side. The method was tested on artificial model systems and used to measure volume changes in renal cultured epithelia (A6) after exposing the serosal surface to hypotonic solutions and replacing cell-impermeable sucrose by an organic compound (glycerol) with a smaller reflection coefficient. Serosal hypotonicity elicited a rapid volume increase followed by regulatory volume decrease, whereas the organic compound replacement caused a steady increase in cell volume.