Understanding the 'Silver Book' - An important reference for standardised nomenclature in clinical laboratory sciences.

Clinical laboratories perform a wide menu of testing (examinations). Successful requesting, examination, and ordering in this environment requires clear standardised nomenclature. The Silver Book (SB) is an IUPAC (International Union of Pure and Applied Chemistry) publication, produced with the support of both IUPAC and the IFCC (International Federation of Clinical Chemistry and Laboratory Medicine), that makes recommendations on logical standardised nomenclature, symbols, properties, and units in many disciplines of the clinical laboratory sciences. These recommendations are founded on and in agreement with the principles and work of the International Organization for Standardization (ISO), Bureau International des Poids et Mesures (BIPM), IUPAC, and the IFCC. Practical applications described are based on those scientific principles. The SB recommendations apply to all types of examination, not only to measurement of quantities but also examination of nominal properties where no magnitude is involved. The SB is applicable not only to clinical chemistry, but to many other clinical laboratory disciplines. For examples, reports regarding haemostasis, toxicology, clinical microbiology, reproduction and fertility, clinical pharmacology, clinical allergology, clinical molecular biology, and clinical immunohaematology have been published by the IUPAC and the IFCC. Peak scientific bodies such as the IUPAC and the IFCC have important roles in the development of sound international standards for nomenclature of examinations. Such standards support safe and effective representation of patient health information, foster portability, and empower future decision support systems.

Recommendations for clinical laboratory science reports regarding properties, units, and symbols: the NPU format.

The document describes the Nomenclature for Properties and Units (NPU) format developed by the joint committee on Nomenclature for Properties and Units of the IFCC and IUPAC. Basic concepts, in particular system, component, kind-of-property, and unit are defined. Generalities concerning quantities and units, and terminological rules are recalled. A constant format is structured for reporting clinical laboratory information. It is adapted for examinations, including measurements, performed in the clinical laboratories. The NPU format follows international recommendations. Using this format, more than 16,000 properties examined in the clinical laboratories have been described. A regularly updated version of the descriptions is available from the IFCC. Examples from different disciplines are given to promote the dissemination of the format. The object of the NPU format is the transfer of examination data without loss of accuracy between the laboratory personnel and the clinicians. The format is well-adapted for comparative and epidemiological studies.

[The virtual slide: a new tool for the External Quality Control for the spermatozoid assessment morphology]. / La lame virtuelle : un nouvel outil pour le contrôle externe de qualité de l'analyse morphologique des spermatozoïdes.

As part of the accreditation procedures, External Quality Control (EQC) must be performed for all biological determinations. In the exploration of male infertility, the spermocytogram is very important because it is often used as first line and an error of interpretation may have dramatic consequences. Alongside the EQC which usely consists of carrying out preparation slides (stained or not), we tested the use of a slide scanned from a stained specimen ("virtual slide"). All participants (n = 57) received a sample of the following supports: an unstained slide, a stained one and a virtual slide, all of them from a single human ejaculate. The required tests were the proportion of typical forms of spermatozoa and the degree of teratozoospermia using the Multiple Abnomalities Index (MAI) according to David's criteria. Results showed that for the two examinations, the dispersion of results remains similar regardless of the support. Furthermore, results seemed no to be influenced by the staining technique. This indicates that the discrepancy between results came from the quality of the observer. Moreover, the numerical values of half the participants were situated in the interval mean of ±â€Š30% for the evaluation of typical forms and ±â€Š15% for MAI. We recommend the virtual slide for EQC spermocytogram to evaluate and improve the reading ability. In addition, we propose to retain an interval of acceptability of ±â€Š30% for the evaluation of typical forms and ±â€Š15% for MAI.

Traceability of values for catalytic activity concentration of enzymes: a Certified Reference Material for aspartate transaminase.

BACKGROUND: A new reference material for the liver enzyme aspartate transaminase (AST) (L-aspartate: 2-oxoglutarate-aminotransferase, EC 2.6.1.1), also called aspartate aminotransferase (ASAT), has been developed under the code ERM-AD457/IFCC. This certified reference material (CRM) for AST has been produced from a human type recombinant AST expressed in Escherichia coli and a buffer containing bovine serum albumin, and has been lyophilised. METHODS: The homogeneity and the stability of the material have been tested and the catalytic activity concentration has been characterised by 12 laboratories using the reference procedure for AST at 37 degrees C from the International Federation of Clinical Chemistry and Laboratory Medicine (IFCC). RESULTS: The certified catalytic activity concentration and certified uncertainty of AST in the reconstituted material are (1.74+/-0.05) microkat/L or (104.6+/-2.7) U/L (with a coverage factor k=2; 95% confidence interval). CONCLUSIONS: Both the certified value and uncertainty are traceable to the International System of Units (SI). The material is aiming to control the IFCC reference procedure for AST at 37 degrees C, which will then be used to assign values to calibrants and control materials. The present paper highlights the scientific challenges and innovations which were encountered during the development of this new CRM.

Clinical laboratory sciences data transmission: the NPU coding system.

In health care services, technology requires that correct information be duly available to professionals, citizens and authorities, worldwide. Thus, clinical laboratory sciences require standardized electronic exchanges for results of laboratory examinations. The NPU (Nomenclature, Properties and Units) coding system provides a terminology for identification of result values (property values). It is structured according to BIPM, ISO, IUPAC and IFCC recommendations. It uses standard terms for established concepts and structured definitions describing: which part of the universe is examined, which component of relevance in that part, which kind-of-property is relevant. Unit and specifications can be added where relevant [System(spec)-Component(spec); kind-of-property(spec) = ? unit]. The English version of this terminology is freely accessible at http://dior.imt.liu.se/cnpu/ and http://www.labterm.dk, directly or through the IFCC and IUPAC websites. It has been nationally used for more than 10 years in Denmark and Sweden and has been translated into 6 other languages. The NPU coding system provides a terminology for dedicated kinds-of-property following the international recommendations. It fits well in the health network and is freely accessible. Clinical laboratory professionals worldwide will find many advantages in using the NPU coding system, notably with regards to an accreditation process.

Procedimientos primarios de referencia de la IFCC para la medición de concentraciones de actividad catalítica de enzimas a 37 ºC: Parte 8. Procedimiento de referencia para la medición de la concentración catalítica de alfa-amilasa [alfa-Amilasa: 1,4-alfa-D-glucan 4-glucanohidrolasa (AMY), EC 3.2.1.1]

Este trabajo es el octavo de una serie dedicada a los procedimientos de referencia para la medición de las concentraciones de actividad catalítica de las enzimas a 37 ºC y a la certificación de las preparaciones de referencia. Otras partes se refieren a: Parte 1. El concepto de los procedimientos de referencia para la medición de las concentraciones de la actividad catalítica de las enzimas; Parte 2. Procedimiento de referencia para la medición de la concentración catalítica de creatina quinasa; Parte 3: Procedimiento de referencia para la medición de la concentración catalítica de lactato deshidrogenasa; Parte 4. Procedimiento de referencia para la medición de la concentración catalítica de alanin aminotransferasa; Parte 5. Procedimiento de referencia para la medición de la concentración catalítica de aspartato aminotransferasa; Parte 6. Procedimiento de referencia para la medición de la concentración catalítica de gamma-glutamiltransferasa; Parte 7. Certificación de cuatro materiales de referencia para la determinación de la actividad enzimática de gamma-glutamiltransferasa, lactato deshidrogenasa, alanin aminotransferasa y creatina quinasa a 37 ºC. El procedimiento que se describe aquí se deduce a partir del método de referencia de la IFCC a 30 ºC descrito previamente. Las diferencias se tabulan y comentan en Clin Chem Lab Med 2006; 44: 1146-55.

Standardization of gamma-glutamyltransferase assays by intermethod calibration. Effect on determining common reference limits.

BACKGROUND: The improvement of the consistency of gamma-glutamyltransferase (GGT) activity results among different assays after calibration with a common material was estimated. We evaluated if this harmonization could lead to reference limits common to different routine methods. METHODS: Seven laboratories measured GGT activity using their own routine analytical system both according to the manufacturer's recommendation and after calibration with a multi-enzyme calibrator [value assigned by the International Federation of Clinical Chemistry and Laboratory Medicine (IFCC) reference procedure]. All samples were re-measured using the IFCC reference procedure. Two groups of subjects were selected in each laboratory: a group of healthy men aged 18-25 years without long-term medication and with alcohol consumption less than 44 g/day and a group of subjects with elevated GGT activity. RESULTS: The day-to-day coefficients of variation were less than 2.9% in each laboratory. The means obtained in the group of healthy subjects without common calibration (range of the means 16-23 U/L) were significantly different from those obtained by the IFCC procedure in five laboratories. After calibration, the means remained significantly different from the IFCC procedure results in only one laboratory. For three calibrated methods, the slope values of linear regression vs. the IFCC procedure were not different from the value 1. The results obtained with these three methods for healthy subjects (n=117) were gathered and reference limits were calculated. These were 11-49 U/L (2.5th-97.5th percentiles). The calibration also improved the consistency of elevated results when compared to the IFCC procedure. CONCLUSIONS: The common calibration improved the level of consistency between different routine methods. It permitted to define common reference limits which are quite similar to those proposed by the IFCC. This approach should lead to a real benefit in terms of prevention, screening, diagnosis, therapeutic monitoring and for epidemiological studies.

IFCC primary reference procedures for the measurement of catalytic activity concentrations of enzymes at 37 degrees C.

This paper is the eighth in a series dealing with reference procedures for the measurement of catalytic activity concentrations of enzymes at 37 degrees C and the certification of reference preparations. Other parts deal with: Part 1. The concept of reference procedures for the measurement of catalytic activity concentrations of enzymes; Part 2. Reference procedure for the measurement of catalytic concentration of creatine kinase; Part 3. Reference procedure for the measurement of catalytic concentration of lactate dehydrogenase; Part 4. Reference procedure for the measurement of catalytic concentration of alanine aminotransferase Part 5. Reference procedure for the measurement of catalytic concentration of aspartate aminotransferase Part 6. Reference procedure for the measurement of catalytic concentration of gamma-glutamyltransferase; Part 7. Certification of four reference materials for the determination of enzymatic activity of gamma-glutamyltransferase, lactate dehydrogenase, alanine aminotransferase and creatine kinase at 37 degrees C. The procedure described here is deduced from the previously described 30 degrees C IFCC reference method. Differences are tabulated and commented on.

Influence of human haptoglobin polymorphism on oxidative stress induced by free hemoglobin on red blood cells.

BACKGROUND: An in vitro study was conducted to determine whether haptoglobin phenotypes differed in their protective effect against oxidative stress induced by extracellular hemoglobin on red blood cells. METHODS: Conjugated dienes and thiobarbituric acid-reactive substances (TBARS) were determined in human red blood cell membranes in the presence of hemoglobin and various concentrations of each type of purified haptoglobin. In addition, the release of K+ and lactate dehydrogenase from red blood cells was measured. RESULTS: A protective effect of haptoglobin was observed in terms of results obtained for the four parameters examined, with significant differences (p<0.001) between the three haptoglobin types; type 1-1 was the most active and type 2-2 the least active. A proportion of oxidative damage was not sensitive to haptoglobin, but to desferrioxamine (an iron chelator), indicating the participation of two actors, hemoglobin and free iron, in the oxidative stress of membrane lipids. CONCLUSIONS: The antioxidant role of haptoglobin and the phenotype dependence were confirmed for preventing possible oxidative damage induced by free hemoglobin and iron release during its catabolism.

Intermethod calibration of alanine aminotransferase (ALT) and gamma-glutamyltransferase (GGT) results: application to Fibrotest and Actitest scores.

Two multi-component scores (Fibrotest and Actitest) have been proposed to evaluate liver fibrosis or necro-inflammatory lesions as an alternative to liver biopsy. This approach requires standardization of alanine aminotransferase (ALT) and gamma-glutamyltransferase (GGT) determinations. For this purpose, ALT and GGT values were assigned to a multi-enzyme material using the appropriate primary reference procedure. This material was used as a common calibrator for sera from 20 patients with viral hepatitis. Measurements were carried out in 11 laboratories, using their own automated routine methods and compared to results obtained using the primary reference procedure. The expression of results in multiples of the upper reference limit worsened the inter-laboratory variation for both enzymes. The multi-enzyme material was commutable for ALT and GGT determination carried out with six analytical systems. Common calibration significantly improved inter-laboratory consistency, which finally reached 1.8% and 3.3% for ALT and GGT, respectively. For each enzyme, it also permitted the retention of a common reference interval for a set of calibrated methods and the improvement of inter-laboratory coherency of Fibrotest and Actitest scores.

A reference material for traceability of aspartate aminotransferase (AST) results.

Standardization of aspartate aminotransferase (AST) determination is highly desirable for inter-laboratory comparison. Serum AST mean values for 20 patients suffering from viral hepatitis showed an inter-laboratory (n = 13) variation of 9.4%. Part of this variation was due to two laboratories using procedures without pyridoxal-5'-phosphate. A traceable AST value was assigned to an enzyme calibrator (EC) through the appropriate International Federation of Clinical Chemistry and Laboratory Medicine (IFCC) primary reference procedure. The EC was commutable for seven routine methods. Common calibration using the EC reduced the inter-laboratory coefficient of variation (CV = 5.9% ) and allowed retention of a common reference interval for a set of routine procedures. Calibration made superfluous the expression of results in multiples of the upper reference limit, which increased inter-laboratory variation (CV = 18.5%). Furthermore, for 92% of patients, calibration with the EC allowed the correction of misclassifications when taking into account the reference interval of the reference procedure. Use of this EC could be proposed to complete the AST reference system.

Determination of lipase catalytic activity in two reference materials: BCR 693 and BCR 694 by titrimetry at constant pH.

Because routine assays for pancreatic lipase catalytic activity are not yet standardized, between-method comparability is very poor. This is mainly due to the lack of reference materials (RMs). The aim of this study was to assign values of catalytic concentration to two human pancreatic lipase RMs, one prepared from human pancreatic juice (BCR 693), the other obtained by recombinant technology (BCR 694). Lipase catalytic activity was assayed in five experienced laboratories, using aliquots from the same lot of triolein emulsion and a standardized titrimetric procedure, optimized with regard to substrate, cofactors and pH. The accepted sets of data (n = 4) gave a mean +/- the corresponding uncertainty expressed as the 0.95 confidence interval of 1732 +/- 72 U/l and 1043 +/- 60 U/l for BCR 693 and 694, respectively. Transferability of the whole operating procedure proved to be quite satisfactory. The authors conclude that both RMs can be used to verify the correct implementation of the standardized measurement procedure and to assign values to secondary lipase materials (commercial calibrators, control products) which, in turn, ensures traceability to the standardized procedure in this study, and contributes to the harmonization of laboratory results according to the Directive for in vitro Diagnostic Medical Devices.

Time-resolved fluorescence allows selective monitoring of Trp30 environmental changes in the seven-Trp-containing human pancreatic lipase.

Human pancreatic lipase (HPL, triacylglycerol acylhydrolase, EC 3.1.1.3) is a carboxyl esterase which hydrolyzes insoluble emulsified triglycerides and is essential for the efficient digestion of dietary fats. Though the three-dimensional structure of this enzyme has been determined, monitoring the conformational changes that may accompany the binding of various substrates and inhibitors is still of interest. Because of its sensitivity and ease of use, fluorescence spectroscopy of the intrinsic Trp residues is ideally suited for this purpose. However, the presence of seven Trp residues spread all over the HPL structure renders the interpretation of the fluorescence changes difficult with respect to the identification and location of the conformational or environmental changes taking place at the various Trp residues. In this context, the aim of this work was to investigate the contribution of the individual Trp residues to the fluorescence properties of HPL. To this end, we analyzed the steady-state and time-resolved fluorescence parameters of five single-point mutants in which one Trp residue was substituted with a weakly fluorescent Phe residue. In addition to the Trp residues at positions 30, 86, and 252, strategically located with respect to the active site, we also mutated Trp residues at positions 17 and 402, as representative residues of the HPL N- and C-terminal domains, respectively. Taken together, our data suggested that the solvent-exposed Trp30 residue contributed to at least 44% of the overall fluorescence of wild-type HPL. Moreover, we found that the long-lived fluorescence lifetime (6.77 ns) of wild-type HPL could be specifically attributed to Trp30, a feature that enables selective monitoring of its environmental changes. Additionally, Trp residues at positions 17 and 402 strongly contributed to the 1.61 ns lifetime of HPL, while Trp residues at positions 86 and 252 contributed to the 0.29 ns lifetime.

Preparation and characterization of reference materials for human pancreatic lipase: BCR 693 (from human pancreatic juice) and BCR 694 (recombinant).

There is a lack of certified reference material (CRM) for lipase catalytic activity. Consequently between-method comparability is very poor. The aim of this study was to produce two lipase CRMs, one from human pancreatic juice (BCR 693), and another using recombinant technologies (BCR 694). Lipase was purified from pancreatic juice, using column chromatography and isoelectric focusing. Recombinant lipase was produced with a transfected cell line and purified with column chromatography. Adding buffered bovine serum albumin and subsequent freeze-drying were used to stabilize both materials. A standardized titrimetric method was employed to compare their catalytic properties to those of two plasma pools of patients suffering from acute pancreatitis. About 5 kU (titrimetry, 37 degrees C) of each material were obtained. They were lyophilized without apparent modifications of their catalytic properties, which stayed identical to those exhibited by the enzyme present in patient's pools. Stability of both materials was estimated at several years when stored in a dry form at -20 degrees C. Both materials appear to have similar catalytic properties and stability and were found commutable as regards a reference method and a routine measurement procedure. An international certification campaign will be carried out to assign values to BCR 693 and BCR 694.

IFCC primary reference procedures for the measurement of catalytic activity concentrations of enzymes at 37 degrees C. Part 1. The concept of reference procedures for the measurement of catalytic activity concentrations of enzymes.

This paper is the first in a series dealing with reference procedures for the measurement of catalytic activity concentrations of enzymes at 37 degrees C and with the certification of reference preparations. Other parts deal with: Part 2. Reference Procedure for the Measurement of Catalytic Concentration of Creatine Kinase; Part 3. Reference Procedure for the Measurement of Catalytic Concentration of Lactate Dehydrogenase; Part 4. Reference Procedure for the Measurement of Catalytic Concentration of Alanine Aminotransferase; Part 5. Reference Procedure for the Measurement of Catalytic Concentration of Aspartate Aminotransferase; Part 6. Reference Procedure for the Measurement of Catalytic fication of Four Reference Materials for the Determination of Enzymatic Activity of y-Glutamyltransferase, Lactate Dehydrogenase, Alanine Aminotransferase and Creatine Kinase at 37 degrees C. A document describing the determination of preliminary reference values is also in preparation.

Evaluation of commutability of control materials.

The commutability of 13 control materials was evaluated by performing parallel measurements on two different analysers: a Synchron CX-5 Delta from Beckman-Coulter and a Vitros 950 from Ortho-Clinical Diagnostics. Twenty three clinical chemistry analytes (substrates, electrolytes and enzymatic activities) were determined in plasma from 15 different patients in order to define intermethod relationship for each analyte. The relationship observed for each control material was compared to those obtained for patients' specimens. The results show that commutability depends both on the tested analyte and on the control material. No totally commutable material has been found for the whole set of tested parameters. Most control materials were commutable for inorganic phosphate, glucose, chloride, triglycerides, alanine aminotransferase, amylase and y-glutamyltransfera-se, but less than a quarter of control materials were commutable for sodium, calcium, creatinine, alkaline phosphatase and lipase. Seven materials were commutable for more than half of the analytes, whereas five control materials were commutable for less than a quarter of these analytes. We propose to verify the commutability of materials before their use in an external quality control assessement.

IFCC primary reference procedures for the measurement of catalytic activity concentrations of enzymes at 37 degrees C. Part 3. Reference procedure for the measurement of catalytic concentration of lactate dehydrogenase.

This paper is the third in a series dealing with reference procedures for the measurement of catalytic activity concentrations of enzymes at 37 degrees C and the certification of reference preparations. Other parts deal with: Part 1. The Concept of Reference Procedures for the Measurement of Catalytic Activity Concentrations of Enzymes; Part 2. Reference Procedure for the Measurement of Catalytic Concentration of Creatine Kinase; Part 4. Reference Procedure for the Measurement of Catalytic Concentration of Alanine Aminotransferase; Part 5. Reference Procedure for the Measurement of Catalytic Concentration of Aspartate Aminotransferase; Part 6. Reference Procedure for the Measurement of Catalytic Concentration of gamma-Glutamyltransferase; Part 7. Certification of Four Reference Materials tamyltransferase, Lactate Dehydrogenase, Alanine Aminotransferase and Creatine Kinase at 37 degrees C. A document describing the determination of preliminary upper reference limits is also in preparation. The procedure described here is deduced from the previously described 30 degrees C IFCC reference method (1). Differences are tabulated and commented on in Appendix 1.

IFCC primary reference procedures for the measurement of catalytic activity concentrations of enzymes at 37 degrees C. Part 2. Reference procedure for the measurement of catalytic concentration of creatine kinase.

This paper is the second in a series dealing with reference procedures for the measurement of catalytic activity concentrations of enzymes at 37 degrees C and the certification of reference preparations. Other parts deal with: Part 1. The Concept of Reference Procedures for the Measurement of Catalytic Activity Concentrations of Enzymes; Part 3. Reference Procedure for the Measurement of Catalytic Concentration of Lactate Dehydrogenase; Part 4. Reference Procedure for the Measurement of Catalytic Concentration of Alanine Aminotransferase; Part 5. Reference Procedure for the Measurement of Catalytic Concentration of Aspartate Aminotransferase; Part 6. Reference Procedure for the Measurement of Catalytic Concentration of gamma-Glutamyltransferase; Part 7. Certification of Four Reference Materials for the Determination of Enzymatic Activity of gamma-Glutamyltransferase, Lactate Dehydrogenase, Alanine Aminotransferase and Creatine Kinase at 37 degrees C. A document describing the determination of preliminary reference values is also in preparation. The pro- described 30 degrees C IFCC reference method (1). Differences are tabulated and commented on in Appendix 3.