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BACKGROUND AND OBJECTIVE: Discrepancies between serum and heparin plasma samples have been described for many commercial troponin assays including the cardiac troponin T (cTnT) assay. Using the current 3rd generation Elecsys Troponin T immunoassay, heparin plasma cannot be recommended for the determination of cTnT due to systematic lower test results caused by a direct interference of the immunoassay by heparin. The purpose of the multicenter study was to evaluate the analytical performance of an improved 4th generation Elecsys Troponin T immunoassay with a special focus on the comparability of cTnT results determined in heparin plasma and serum. METHODS AND RESULTS: The multicenter evaluation was performed in 10 clinical laboratories according to a standardized protocol (Roche Diagnostics, Penzberg, Germany, Study No. B05P008). The Elecsys Troponin T immunoassay was performed on the Modular Analytics E170 and Elecsys 2010 systems. Intraassay imprecision (n = 21) and total imprecision (2 runs/d, 10 days, triplicate measurements) were evaluated using 2 commercial controls (Roche Diagnostics) and 6 different serum pools (cTnT: 0.0140 - 4.102 microg/L). Intraassay CVs ranged from 0.73 to 3.22%. Total imprecision CVs ranged from 3.61 to 35.45% (cTnT < 0.1 microg/L) and 1.82 to 9.09% (cTnT > 0.1 microg/L), respectively. The cut-off for myocardial necrosis was determined to be 0.03 microg/L using the 10% total imprecision CV criteria. Linearity was assessed by serial dilutions of 6 different serum samples using cTnT negative serum pools. Linearity was proven up to 21.3 microg/L (recoveries: 90% - 110%). Regression data of all comparison studies were calculated according to the method of Passing and Bablok. The method comparison between the 4th generation and the commercially available cTnT immunoassay showed highly similar results across the whole measuring range (0.01 - 25.0 microg/L): y = 1.024x -0.001, r = 0.998; n = 988. Using the commercially available cTnT reagent, the serum to heparin plasma comparison yielded a systematic bias to approximately 8% lower cTnT results in heparin plasma. However, suitable comparability was obtained using the 4th generation Elecsys cTnT assay. The regression analysis (serum vs. heparin plasma) across the studied measuring range (cTnT: 0.01 - 14 microg/L) yielded the following equation: y = 0.975x + 0.001; r = 0.986; n = 403. However, rare individual serum to matched heparin plasma samples still yielded poor comparability (deviation > 20%) using the 4th generation Elecsys Troponin T immunoassay. CONCLUSION: Our data confirm an excellent analytical performance of the improved troponin T immunoassay. Most importantly, no systematic bias between cTnT results determined in serum and heparin plasma was observed from data obtained in 7 evaluation sites. The performance of the 4th generation Elecsys Troponin T assay is therefore comparable to other commercially available troponin immunoassays. Further studies are necessary to investigate the cause of poor comparability of cTnT results in rare individual serum to matched heparin plasma samples.

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The objetive of this work was to elaborate cotija type cheese prepared with whole milk and chickpea (Cicer arietinum L.), inoculated with S. Thermophilus and to compare its physicochemical, microbiological and sensorial characteristics with a commercial cheese. Two mixture were selected 70:30 and 80:20 (whole milk:chickpea paste). Both mixture were ground, pasteurized and inoculated with. S. Thermophilus, to develop taste and aroma. Two rennet concentrations (1:10,000 and 2:10,000), lactic acid and 50 per cent CaCl2 solution were used in both products. Results showed that cheese made with 70:30 mixture and 1:10,000 rennet concentration gave a weak curde and 12 per cent of total solids were lost; in the same way as 70:30 mixture and 2:10,000 rennet concentration. Nevertheless, cheese made with 80:20 mixture and 10,000 or 2:10,000 rennet concentration showed hard consistency of its curd. Addition of 10 per cent sodium chloride solution to he 80:20 mixture cheese, made better whey drain, and a cotija type cheese with similar sensory characteristics as a whole milk cheese, was obtained. Chemical and physical analysis of the extended cotija type cheese showed 14.3 +/- 0.42 and 15.5 +/- 0.21 g/100 g of protein and lipid content respectively. Microbiologically, the extended cotija type cheese is pathogenic microorganisms free for human consumption. Sensory evaluation of the chickpea extended cheese showed a 80 per cent acceptance while the acceptance of the whole milk commercial cheese was 90 per cent.

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OBJECTIVE: Assessment of preanalytical and storage conditions for selenium determination in urine. DESIGN AND METHOD: A design is established for the study of the effect of HCl as sample preservative, and for the stability of urine samples with time and temperature of storage. The effect of sample sonication before taking aliquots is also evaluated. All measurements are performed using hydride generation atomic fluorescence spectrometry. Selenium concentrations measured from 52 urine samples of healthy population in Barcelona are used for an estimation of the selenium reference level. RESULTS: HCl addition to urine samples has no effect on Se stability. Significant differences are due to time and temperature of storage. The Se reference level in urine samples from population in Barcelona area is estimated to be 22.8 +/- 6.7 microg Se g(CT)(-1) (CT: creatinine). CONCLUSIONS: No significant differences are observed in selenium content when HCl is added as preservative. The Se content remains constant at room temperature for one day, for a week at 4 degrees C and for a fortnight when stored at -20 degrees C.

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A retrospective study of stat and routine laboratory analysis turnaround time was performed in a 1000-bed public hospital before and after the implementation of instrument and computer changes. Significant decreases in turnaround time were found for enzyme tests in the stat laboratory and for all analytes studied in the routine laboratory. The decrease in TAT was evaluated using a physician satisfaction scale, elaborated in conjunction with specialists from several fields, that disclosed an increase in perceptive quality. Results from other authors and recommendations by the College of American Pathologists for turnaround time are discussed.

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The pharmacokinetics of gentamicin in adult patients with endocarditis were studied. The records were reviewed for 64 patients treated for bacterial endocarditis and for whom serum gentamicin concentrations had been requested between May 1990 and May 1993. The patients were divided into those with serum creatinine concentration (SCr) <1.2 mg/dL and those with SCr > or = 1.2 mg/dL. The measured serum gentamicin concentrations, patient demographic information, dosage interval, and SCr were entered into a pharmacokinetics program for analysis. The pharmacokinetic values evaluated were steady-state distribution volume (V), clearance (CL), elimination rate constant (k), and half-life (t1/2). The mean +/- S.D. t1/2 and V of gentamicin were 4.7 +/- 2.4 hr and 0.29 +/- 0.11 L/kg. Half-life was correlated with SCr and V. These two variables may explain 66% of the variation in t1/2. No difference in V was observed between patients with normal versus abnormal SCr. Men had a lower k than women. V and CL were lower in patients under age 60 than in older patients. Adult patients with endocarditis may have expanded gentamicin V. V and CL accounted for most of the variation in gentamicin t1/2.

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Analytical performance and practicability of the new Boehringer Mannheim/Hitachi 747 analysis system were assessed in a multicentre evaluation involving four laboratories. The analytical performance was evaluated according to a protocol similar to the ECCLS guidelines and comprised 13 analytes including enzymes, substrates and electrolytes. About 65,000 results were obtained within three months. The evaluation was planned and supported by a program system called "Computer Aided Evaluation". Acceptance criteria have been established for judging the results. The median of the within-run coefficients of variation (CVs) in control sera of all methods was below 1%, being far below the acceptance limit of 2%. The median of CVs of between-days imprecision was below 2% (acceptance criterion 3%). The high degree of precision prompted us to set up a biometrical model suitable for the differentiation between deviant points, outliers and measurements that can still be explained by the system performance. No relevant drift effects were observed during eight hours. The methods were linear over a wide range, avoiding rerun analysis in most cases. No sample-related carry-over was found. Reagent-dependent carry-over outside the acceptance limits was measured from uric acid to phosphorus to a slight extent, and from triacylglycerols to lipase, as well as from total protein to bilirubin to a perceptible degree. It can be avoided by separating these reagent combinations in the channel arrangement. Taking a systematic deviation of more than 10% as unacceptable, four of the 13 analytes suffered from interference by haemoglobin, one by bilirubin and one by turbidity. The Boehringer Mannheim/Hitachi 747 analysis system is capable of determining serum indices which in combination with the interferogram allow an assessment of the interference. With the exception of chloride the recovery of the assigned values for all control sera showed values between 95 and 105%. Out of 40 method comparison studies for enzymes and substrates, 31 yielded regression equations with less than 5% proportional errors and less than 5% constant errors. Deviations exceeding these acceptance criteria can be explained by differences in the reagent formulation, in the method employed or in calibration. The agreement of the ISE method comparisons was within a +/- 5% deviation over a wide analytical range. Practicability of the Boehringer Mannheim/Hitachi 747 analysis system was assessed with the help of a questionnaire, in which properties of the instrument were quantified, thus permitting a relatively objective rating. The 190 questions were placed in 14 groups, each dealing with an attribute of the instrument.(ABSTRACT TRUNCATED AT 400 WORDS)

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We present the results of a multicentre evaluation with Boehringer Mannheim/Hitachi instruments of new "enzymatic" methods for the determination of Na+, K+, and Cl- in serum or plasma. The between-day coefficient of variation was less than 1.4% (Na+), less than 2.6% (K+) and less than 1.7% (Cl-). The linear range of the assays were at least 80 to 200 mmol/l (Na+), 1.5 to 17 mmol/l (K+) and about 30 to at least 200 mmol/l (Cl-). The comparisons with routine flame atomic emission spectrometry and coulometry showed a satisfactory agreement of the test results. The "enzymatic" assays are insensitive to even grossly elevated levels of bilirubin and lipids (sodium, potassium, and chloride assays), NH4+ (potassium assay) and amylase (chloride assay). Interference by various drugs was not detected. Since the new methods can easily be adapted to photometric clinical chemistry instruments, they represent a valuable alternative to the use of ion-selective electrodes, flame atomic emission spectrometry and coulometry.

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