[Glossary of the acronyms for the institutions concerned by metrology]. / Glossaire des acronymes d'institutions relevant de la métrologie.

Metrology and one of its contributions, metrological traceability represent two fundamental developments for the clinical laboratories. Several international and national institutions take part in these developments. They elaborate recommendations going from concepts to implementation in the clinical laboratories. These activities are helpful for accrediting clinical laboratories.

[Introducing the new international vocabulary of metrology]. / Présentation du nouveau Vocabulaire international de métrologie.

The 3rd edition of the "International vocabulary of metrology - Basic and general concepts and associated terms (VIM)" is a fundamental document for the people who are concerned by metrology. This international standard is bilingual (french/english). The VIM contains definitions of metrological concepts, their hierarchy, numerous explicative notes and examples. This approach confirms that the concepts of the VIM are applicable to various disciplines including clinical laboratory sciences.

[Recommendations for metrological control of measuring equipments in the clinical laboratories]. / Recommandations pour la maîtrise métrologique des équipements de mesure au laboratoire d'analyses de biologie médicale (Document D).

The control of the measuring equipment (balances, mass standards, micropipettes, dilutors, volumetric glassware, thermometers...) is essential to obtain reliable analytical results. This control requires knowledge and use of the main standards, instructions for use, metrological verifications and confirmations as well as creation of checking and standardizing certificates ensuring metrological traceability. These items should help to control the quality of the analytical performances (fidelity and trueness in particular).

[Recommendations for expressing uncertainty of measurement of quantitative results in laboratory medicine]. / Recommandations relatives à l'expression de l'incertitude de mesure des résultats quantitatifs en biologie médicale (Document F).

In laboratory medicine, the quantitative results of examinations are interpreted with regard to reference intervals, clinical decision limits or previous results of a patient, from which it is necessary to inform the clinician about the uncertainty of measurement linked to the value of the result. This document explains the problematic of the expression of the uncertainty of measurement. It proposes recommendations concerning a simple way to evaluate uncertainty of measurement using long term internal quality control data and the value of the uncertainty linked to the method calibration. It approaches the determination of analytical goals and the choice of methods and also the comments accompanying the record of results and a help to their interpretation.

Carnitine in human polymorphonuclear leukocytes, mononuclear cells, and platelets.

We tried to study the distribution of carnitine in human blood. Total carnitine (free plus acylcarnitine) was determined in red blood cells, polymorphonuclear leukocytes, mononuclear cells, platelets, and plasma from 15 apparently healthy adults. We did not find carnitine in red blood cells but found it in significant amounts in polymorphonuclear leukocytes and mononuclear cells, 52.2 +/- 16.9 and 41.9 +/- 9.3 mumol/10(9) cells (mean +/- 1 SD), respectively. We also found that platelets contain carnitine in small amounts, 49.0 +/- 8.4 nmol/10(9) cells. In plasma the carnitine concentration was 51.5 +/- 3.3 mumol/L. We conclude that blood carnitine is localized mainly in polymorphonuclear leukocytes and mononuclear cells (83% of whole-blood carnitine).

Interassay calibration as a major contribution to the comparability of results in clinical enzymology.

OBJECTIVE: Factors contributing to the applicability of interassay calibration of methods measuring enzyme catalytic activities are described. Also discussed are the properties essential for such a material. Similarity of specificity for the methods to be calibrated as well as commutability between the material(s) intended to be used as calibrator are the main criteria to be satisfied. RESULT: Several examples demonstrated that interassay calibration is feasible but a multi-enzyme calibrator with a wide commutability for the most popular methods remains to be developed. This is the project of the IFCC Working Group on Calibrators in Clinical Enzymology (WG-CCE). Several experimental data are also presented that indicate that the temperature at which the reaction is carried out is not a limiting factor in the implementation of interassay calibration in clinical enzymology.

Validation of an enzyme calibrator--an IFCC guideline. International Federation of Clinical Chemistry.

OBJECTIVES: The objective of this guideline is to improve standardization in clinical enzymology in order to improve intermethod comparability of patients' results. DESIGN AND METHODS: The reference system, combination of the reference method and the reference material, is used to produce a reference value for a given catalytic activity. Sets of methods are formed of methods exhibiting the same analytical specificity. Materials intended to be used as enzyme calibrators are experimentally checked for their commutability. RESULTS: The transfer of accuracy from the reference value to patients' results is dependent on methods (analytical specificity) and on materials (experimentally assessed commutability). The feasibility of this approach was demonstrated with materials of high level for several enzymes and for each of them for several routine methods. CONCLUSION: Expected advantages of this approach in clinical enzymology are presented.

Preparation of enzyme calibration materials.

Standardisation in clinical enzymology needs not only reference methods but also reference materials. While single-enzyme reference enzymes have been developed, a multienzyme certified reference material (MECRM) available in high amount remains to be produced. To transfer trueness from the value of the reference system to patients' results, validated enzyme calibrators (EC) are also needed. Both the MECRM and the ECs must exhibit the same catalytic properties as the corresponding enzymes in human plasma. Moreover, commutability of these materials with patients' samples must be experimentally tested for one or a set of methods defined by an analytical specificity equal to that of the reference method. Various experimental studies have shown that the commutability of an enzyme material depends on the source of enzyme and its purification process, the matrix (including cofactors, effectors, additives, stabilisers... ) and the mode of processing of the final material. To promote intermethod calibration in clinical enzymology, a collaborative programme between the International Federation of Clinical Chemistry and Laboratory Medicine (IFCC), Institute for Reference Materials and Measurements (IRMM, Geel, Belgium) and IFCC corporate members is in progress for the development of a MECRM containing amylase, ALT, AST, ALP, CK, GGT, LDH, and lipase and exhibiting a wide and defined commutability.

Modifications of plasma enzyme activities after severe head injury; evaluation of prognosis using multivariate methods.

The aim of this study was to analyse the plasma variations of four enzymatic activities (lactate dehydrogenase, aldolase, creatine kinase, aspartate aminotransferase) in 134 patients suffering from severe head injury. Enzymatic activities were assayed daily for 3 days after the trauma. Means of the four enzymatic activities were significantly different according to their evolution (death or survival), except for creatine kinase, 48 h after the trauma. Multivariate analysis indicated that lactate dehydrogenase and aldolase levels were useful in order to discriminate between potential survivors and non-survivors. The value of multivariate analysis in head traumatology is discussed.

[Value of C-reactive protein determination in cranial traumatology]. / Intérêt de la détermination de la protéine C réactive en traumatologie crânienne.

Serum C reactive protein can be assayed precisely and specifically by immunonephelometry. This protein was determined daily for four days in 102 patients suffering of a skull trauma. Skull trauma without any complication (n=43) did not lead to a significant increase of C reactive protein level, in contrast to skull trauma complicated by an intracranial haematoma (n=32), in patients with profound coma (n=17) and in cases leading to a fatal issue (n=10). C reactive protein concentrations in uncomplicated skull trauma were found to be significantly different from those of the three series of complicated situations. C reactive protein patterns were correlated with the evolution of the trauma. It is therefore recommended that C reactive protein concentrations in serum should be determined daily during four days following the accident.

Diagnostic value of C-reactive protein and transthyretin in bone infections of the lower limb.

In a prospective study, white and red blood cell counts, hematocrit, erythrocyte sedimentation rate (ESR), albumin, alpha-1 acid glycoprotein, C-reactive protein (CRP), and transthyretin (TTR) values were determined by serial measurements during 23 days in 80 patients with an open fracture of the lower limb. Postoperative reference profiles were defined in 74 patients without septic complications. In the six remaining patients, serum CRP and TTR concentrations were found efficient for the early diagnosis of postoperative infections: a CRP/TTR mass concentration ratio higher than 0.6 from the 8th day after surgery was sensitive (100%) and specific (93%). Variations of CRP and TTR concentrations often preceded the clinical diagnosis in patients with early infection. ESR was found unreliable with regard to postoperative infection because of its high dependence with respect to red blood cell count.

Incomplete or absent acute phase response in some postoperative patients.

In a prospective study, 74 patients were admitted for an open fracture of the lower limb and treated by osteosynthesis. None of them presented infectious complication during the postoperative period. Among them, 67 exhibited a classical acute phase response. In 5 patients, the response was apparently incomplete since no serum C-reactive protein (CRP) rise was observed after the injury; i.e. CRP concentrations remained inferior to the detection limit of the assay used; in contrast, serum alpha-1 acid glycoprotein (AAG) concentrations were temporarily increased, a variation associated with a concomitant decrease of transthyretin (TTR) concentration. In 2 other patients, CRP and AAG levels were not significantly modified. The 7 patients did not suffer hepatic insufficiency or protein malnutrition. In our series, incomplete or absent acute phase response was not rare (prevalence 9%) and was not related to an increased risk of postoperative infection. In contrast to CRP, the TTR response, i.e. a transitory decrease, was observed in all the 7 patients.

Catalytic properties and stability of lipase purified from human pancreatic juice.

Catalytic properties of a preparation of human pancreatic lipase purified from pancreatic juice have been compared to those of the enzyme present in pooled plasma from patients suffering from acute pancreatitis. They were very similar as regards influence of effectors (sodium deoxycholate, colipase and Ca2+), optimal pH and apparent KM in optimized conditions. The stability of the preparation appeared to be satisfactory. It was found to be stable for at least 200 days in a liquid form at +4 degrees C and predictive degradation rates per year of the lyophilized form at +4 degrees C and -20 degrees C were 0.06% and 0.00%, respectively. The close similarity of properties of this preparation with those of a recombinant human pancreatic lipase produced in V79 Chinese hamster lung cells suggests that both approaches (purification from human pancreatic juice and gene transfer technology) could be used to produce a suitable reference material for this enzyme.

Production and certification of an enzyme reference material for adenosine deaminase 1 (BCR 647).

BACKGROUND: We describe the preparation of a lyophilised reference material containing purified human adenosine deaminase 1 and the certification of its catalytic concentration. METHODS: The enzyme was purified from human erythrocytes. RESULTS: The enzyme was >99% pure on polyacrylamide gel electrophoresis. Only trace amounts (<0.4%) of alanine aminotransferase, aspartate aminotransferase and L-lactate dehydrogenase were detected in the purified fraction. The purified adenosine deaminase had a molar mass of 41600 g/mol and an isoelectric pH at 4.7, 4.85 and 5.0. The material was prepared by diluting the purified adenosine deaminase in a matrix containing 50 mmol/l Tris-HCl buffer pH 7.4 and 30 g/l human serum albumin; dispensing in vials and freeze-drying. The batch was homogeneous and the predicted loss of adenosine deaminase activity per year on the basis of accelerated degradation studies was 0.006% at -20 degrees C and 0.04% at 4 degrees C. The certified value for adenosine deaminase catalytic concentration in the reconstituted reference material is (2.55+/-0.09) microkat/l when measured by the method that uses adenosine as substrate and glutamate dehydrogenase as auxiliary enzyme at 37 degrees C. CONCLUSIONS: The material can be used to verify the comparability of results from different laboratories, for intra-laboratory quality control, or for calibration of the adenosine deaminase catalytic concentration measurements.

Soybean oil, blackcurrant seed oil, medium-chain triglycerides, and plasma phospholipid fatty acids of stressed patients.

Thirty-six adult severe head injury and cerebral stroke patients in four intensive-care units were randomized to receive one of three enteral diets for 21 days. These diets, which supplied 45% of calories from fat, differed only in lipid composition. Diet A was comprised of 100% soybean oil, diet B contained a 50:50 (wt/wt) mixture of soybean oil and medium-chain triglycerides (MCTs), and diet C contained 42.5% MCT, 50% soybean oil, and 7.5% blackcurrant seed oils. Plasma phosphatidylcholine and fatty acid composition of plasma total phospholipids were determined before initiating treatment (day 0) and weekly throughout the study. Results indicated that at the start of the study, all patients had low linoleic acid (18:2 omega 6) levels compared with healthy subjects. Emulsion A disturbed the balance between several fatty acids of the omega 6 series, as exemplified by the significant increase in 18:2 omega 6 proportions. In contrast, both emulsions B and C introduced a less-pronounced rise in 18:2 omega 6 associated for emulsion C with a significant increase in dihomo-gamma-linolenic acid (20:3 omega 6) and docosapentaenoic acid (22:5 omega 3) in plasma phospholipids. Furthermore, 18:3 omega 6 change was significantly different between groups A and C and that of 20:3 omega 6 between group A and both groups B and C. Throughout the study, arachidonic acid (20:4 omega 6) exhibited remarkable steady-state levels regardless of the diet. This study shows that providing the injured body with high amounts of 18:2 omega 6 does not lead to high levels of its upper derivatives in plasma phospholipids.(ABSTRACT TRUNCATED AT 250 WORDS)

Composition of phospholipid fatty acids in red blood cell membranes of patients in intensive care units: effects of different intakes of soybean oil, medium-chain triglycerides, and black-currant seed oil.

Fatty acid composition of phospholipids in red blood cell membranes was studied in 32 severely head-injured or cerebral stroke patients receiving enteral nutrition for 3 weeks. During this study the effects of three diets differing only by their lipid composition were investigated. The daily energy intake of each patient amounted to 2950 kilocalories, of which the lipid fraction represented 45.7%. Diet A contained only soybean oil, diet B consisted of a 50% soybean oil and 50% medium-chain triglycerides mixture, and diet C was an emulsion of 50% soybean oil, 42.5% medium-chain triglycerides, and 7.5% black-currant seed oil. Our results showed no biochemical signs of fatty acid deficiency in red blood cell membranes for the patients at the beginning of the study, after a comparison with a control group of 20 healthy adults. Inhibition of delta 6-desaturase activity on linoleic acid (C18:2 omega 6) after diet A was suggested by an increase of linoleic acid without a corresponding increase of dihomo-gamma-linolenic acid (C20:3 omega 6). Replacing 50% of soybean oil by with medium-chain triglycerides (diet B) prevented this enzyme inhibition. Supply of black-currant seed oil rich in gamma-linolenic (C18:3 omega 6) and stearidonic (C18:4 omega 3) acids (diet C) induced significant increases of dihomo-gamma-linolenic and eicosapentaenoic (C20:5 omega 3) acids, without influencing arachidonic acid (C20:4 omega 6) levels. This balance was evaluated through the ratio (C20:3 omega 6 + C20:5 omega 3)/C20:4 omega 6.

[Expression of results in clinical biology: current update]. / Expression des résultats en biologie clinique: actualités.

The aim of this review is to present some essential characteristics of the International System of Units (SI), especially the base kinds of quantities, units and symbols. IUPAC and IFCC recommendations to report results from clinical laboratories are indicated, including some recent developments in the nomenclature of derived quantities. It is constantly necessary to indicate 3 parts of a format, i.e. the system, the measured component or process and the kind of quantity. Each part of this format may be supplemented with information to improve understanding and comparability of data obtained at different calendar times or coming from different patients or from different laboratories. The proposed format is flexible enough to accept technical changes and is well adapted to microcomputers.

[Practicality of centrifugal analysis]. / Praticabilité de l'analyse centrifuge.

The practicability of a method or of an apparatus is one of the "figures of merit" which are used by the clinical chemist to choose a method or an apparatus. Joined to the reliability and the efficiency, it has to be evaluated by different tests. Unfortunately, few reflections concern the definition of this criterion, which often is little discussed in the other divisions of the pure and applied chemistry. The clinical chemist is well suited to study and evaluate the practicability. The present paper attempts to define this criterion and to set the discussion of this question.

[Determination of plasma creatinine with centrifugal analyser]. / Etude de la méthode de détermination de la créatinine plasmatique à l'analyseur centrifuge.

An automated kinetic method to determine creatinine in plasma with Jaffé reaction (alkaline picrate reagent) using a Gemsaec analyser is studied in order to argue the precision and the accuracy. The analysis of the reaction rate of a primar standard solution and of different plasmas suggests that a rapid measure is requisite in order to avoid interferences from chromogens contained in plasma which develop a same but often slower and durabler coloration at the used wavelength. The method is compared to the manual procedure using adsorption on Lloyd's reagent.

[The enzymes of the enterocyte. Prospects for a functional exploration]. / Les enzymes de l'entérocyte. Perspectives pour une exploration fonctionnelle

The authors recall the enzymatic activity and transport activities which were localised in the glycocalyx, the microvillous membrane, the intracellular compartment and the basolateral membrane of the enterocyte. The relationships between the processes of digestion and absorption, on the one hand, active transport, energy metabolism and sodium and potassium dependent ATPase, on the other hand are considered. The application of these data to functional investigation of the enterocyte is discussed, emphasizing the complementary character of the biological tests used currently and the importance of sodium and potassium dependent ATPase in the phenomena of active transport.