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1.
Orthop Traumatol Surg Res ; 100(2): 217-20, 2014 Apr.
Article in English | MEDLINE | ID: mdl-24582652

ABSTRACT

BACKGROUND: Periprosthetic joint infection often raises diagnostic challenges, as the published criteria are heterogeneous. New markers for predicting periprosthetic infection have been evaluated. Here, we assessed one of these markers, C-reactive protein (CRP), in joint fluid. HYPOTHESIS: We hypothesised that intra-articular CRP levels would perform better than serum CRP concentrations in diagnosing knee prosthesis infection. PATIENTS AND METHODS: We prospectively included 30 patients including 10 with native-knee effusions, 11 with prosthetic-knee aseptic effusions, and 11 with prosthetic-knee infection defined using 2011 Musculoskeletal Society criteria. Serum CRP was assayed using turbidimetry or nephelometry and intra-articular CRP using nephelometry. Appropriate statistical tests were performed to compare the three groups; P values < 0.05 were considered significant. RESULTS: Serum and intra-articular CRP levels were 5- to 16-fold higher in the group with periprosthetic infection than in the other two groups. Although the areas under the ROC curves were not significantly different, the likelihood ratios associated with the selected cut-offs suggested superiority of intra-articular CRP: a value > 2.78 mg/L suggested possible infection (100% sensitivity and 82% specificity) and a value > 5.37 mg/L probable infection (90% sensitivity and 91% specificity). DISCUSSION: Our findings suggest a possible role for intra-articular CRP assay in diagnosing knee prosthesis infection and perhaps periprosthetic infection at any site. LEVEL OF EVIDENCE: Level III, diagnostic study, development of a diagnostic criterion in consecutive patients comparatively to a reference standard.


Subject(s)
C-Reactive Protein/analysis , Knee Prosthesis/adverse effects , Prosthesis-Related Infections/diagnosis , Adult , Aged , Aged, 80 and over , Arthroplasty, Replacement, Knee , Biomarkers/blood , Female , Humans , Male , Prospective Studies , Prosthesis-Related Infections/blood , Sensitivity and Specificity
3.
Ann Biol Clin (Paris) ; 62(6): 701-5, 2004.
Article in French | MEDLINE | ID: mdl-15563430

ABSTRACT

The aim of the study was to check if a slight and non visible hemolysis to naked eye such as that induced by blood coagulation could interfere in the immunonephelometric measurement of haptoglobin, and if this interference was dependent on the protein phenotype. Results confirmed that blood coagulation induced a non visible hemolysis whose intensity markedly varied from one specimen to another. Under our conditions (kinetic measurement with a Beckman Coulter immunonephelometer), we observed with the sera a negative interference linked to the hemolysis induced by blood coagulation when compared to corresponding plasmas obtained with lithium heparinate (p < 0,005). It was checked also that this anticoagulant did not induce a positive interference. Hemolysis interference was not found phenotype dependent. These results lead us to recommend to perform haptoglobin measurements on heparinised plasmas.


Subject(s)
Haptoglobins/analysis , Hemolysis , Adult , Aged , Aged, 80 and over , Blood Chemical Analysis , Female , Humans , Male , Middle Aged , Phenotype
4.
Ann Biol Clin (Paris) ; 62(6): 717-20, 2004.
Article in French | MEDLINE | ID: mdl-15563433

ABSTRACT

Effect of a pyridoxal phosphate (PP) supplementation of reagents used for ALT and AST measurement was studied in serum of 20 patients suffering from viral hepatitis. Measurements of enzyme activities were carried out at 37 degrees C, using an automate (AU 600, Olympus). Significant differences (p < 0.0001) were observed both for ALT and AST, meanwhile they were more marked for ALT than for AST. This difference was associated with a strong interindividual variability regarding PP activation effect on ALT. In conclusion, aminotransferase measurements should be carried out with a reagent supplemented with PP, when the enzyme activity is used to evaluate a cytolysis. The same recommendation applies when ALT results are integrated into various combinations developed for the evaluation of liver status.


Subject(s)
Alanine Transaminase/blood , Alanine Transaminase/drug effects , Aspartate Aminotransferases/blood , Aspartate Aminotransferases/drug effects , Hepatitis, Viral, Human/blood , Hepatitis, Viral, Human/enzymology , Pyridoxal Phosphate/pharmacology , Adult , Aged , Female , Humans , Male , Middle Aged
5.
Int J Pharm ; 282(1-2): 131-40, 2004 Sep 10.
Article in English | MEDLINE | ID: mdl-15336388

ABSTRACT

The potential of a reverse water-in-fluorocarbon (w-in-FC) emulsion stabilized with a semifluorinated amphiphile, namely C8F17(CH2)11OP(O)[N(CH2CH2)2O]2 (F8H11DMP) for drug delivery through intrapulmonary administration was investigated in the mouse. This study involved assessment of the effect of single or repeated intranasal instillations of a plain emulsion on lung tissue integrity, and evaluation of blood glucose levels in mice treated with an insulin-loaded emulsion. When instilled intranasally to mice, the plain emulsion did not alter lung tissue integrity, as demonstrated by histological staining, and did not induce any airway inflammatory reaction. Treated mice exhibited decreased body weight within the 3-4 days that followed the first emulsion administration, but this decrease was reversible within few days. Mice instilled intranasally with the insulin-loaded emulsion displayed decreased blood glucose levels within the 20 min that followed the administration, thus demonstrating the potential of the reverse w-in-FC emulsion stabilized with F8H11DMP to systemically deliver drugs, including peptides, upon lung administration.


Subject(s)
Drug Delivery Systems , Fluorocarbons/chemistry , Lung/metabolism , Administration, Intranasal , Animals , Blood Glucose/metabolism , Body Weight/drug effects , Bronchoalveolar Lavage Fluid/cytology , Emulsions , Hypoglycemic Agents/administration & dosage , Hypoglycemic Agents/pharmacology , Indicators and Reagents , Insulin/administration & dosage , Insulin/pharmacology , Male , Mice , Mice, Inbred BALB C
7.
Ann Biol Clin (Paris) ; 60(3): 281-6, 2002.
Article in French | MEDLINE | ID: mdl-12050043

ABSTRACT

Results of catalytic activities of enzymes are highly dependent on the measurement procedures and on local conditions. Thus, only poorly marked improvement of interlaboratory comparability of results have been observed in clinical enzymology. To solve this problem, SFBC and IFCC have proposed to use "validated enzyme calibrators". Standardised operating procedures adapted to 37 C have been developed by IFCC for the most commonly used enzymes in clinical chemistry, and will be soon published. Reference materials which have been certified with these SOPs can be used as calibrators for a set of measurement methods which exhibit the same analytical specificity. Calibrators must be commutable, a property that must be checked experimentally. It is possible to produce stable and commutable materials for the calibration of a set of methods. Interest of this approach has been demonstrated for several enzymes. Results of two studies presented here show that the comparison of results to the upper limit of reference ranges does not improve the interlaboratory comparability of results in contrast to the calibration of different methods by a common calibrator which allowed to reach an interlaboratory CV close to 4% for ALT and gammaGT.


Subject(s)
Enzymes/blood , Calibration , Catalysis , Chemistry, Clinical/methods , Humans , Sensitivity and Specificity
8.
Ann Biol Clin (Paris) ; 59(3): 291-7, 2001.
Article in French | MEDLINE | ID: mdl-11397677

ABSTRACT

The large metrological variation (CV, about 25%) observed between laboratories, at the national French level, for the measurement of enzymatic activities results in a loss of efficiency in using laboratory results. Current data show that the standardisation of methods is insufficient to solve this problem and needs to be completed by an harmonisation of the practices including the use of a common reference (calibrator). The present work, carried out by the joint working group between laboratories of the Centres for Periodic Health Examination and the French Society of Clinical Biology (SFBC), deals mainly with the feasibility and evaluation of the improvement of the consistency of the results. Twenty laboratories participated in this study. Five independent surveys were conducted during an height month period. Two enzymes were selected because of their clinical importance and their interest in prevention, screening, diagnosis or epidemiology: ALT (alanine aminotransferase) and GGT (gamma-glutamyltransferase). In each survey three kinds of samples i.e. control sera, candidate calibrators and human serum pools, each of them at two levels of activity (one physiological and the other pathological) were measured in duplicate. The low intra-laboratory imprecision and the high degree of the standardisation of used methods, due to an important effort previously done in this field, permitted to consider a common calibration. The stability and mainly the commutability, i.e. the ability for the candidate calibrator to show a behaviour similar to that of human samples towards the used methods, allowed to reduce the inter-laboratory variation by a half to two third-fold, reaching a coefficient of variation < 5% similar to those observed for cholesterolemia or glycemia. This level of consistency should permit to use common reference limits and common decision limits, after validation of this approach in real practice. The consequences of the harmonisation of practices, extended to the all laboratories, exceed largely the scope of this study. The reduction of the uncertainty and a better approach of the accuracy for the measurement of enzymatic activities should led to a real benefit for the patients in terms of prevention, screening, diagnosis or therapeutic monitoring and consequently for the public health.


Subject(s)
Clinical Enzyme Tests/standards , Laboratories/standards , Alanine Transaminase/blood , Calibration , Epidemiologic Methods , France , Humans , Quality Assurance, Health Care , Quality Control , Reference Values , Reproducibility of Results , Societies, Scientific , gamma-Glutamyltransferase/blood
11.
Clin Biochem ; 31(6): 489-94, 1998 Aug.
Article in English | MEDLINE | ID: mdl-9740971

ABSTRACT

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.


Subject(s)
Clinical Laboratory Techniques/standards , Enzymes/analysis , Calibration , Enzymes/standards , Humans , Reference Standards , Temperature
12.
Clin Biochem ; 31(6): 495-500, 1998 Aug.
Article in English | MEDLINE | ID: mdl-9740972

ABSTRACT

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.


Subject(s)
Clinical Laboratory Techniques/standards , Enzymes/analysis , Calibration , Humans , Reference Standards , Reproducibility of Results
13.
Clin Chim Acta ; 278(2): 151-62, 1998 Dec.
Article in English | MEDLINE | ID: mdl-10023822

ABSTRACT

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.


Subject(s)
Calibration , Enzymes/metabolism , Reference Standards , Catalysis , Humans , Viscosity
14.
Ann Biol Clin (Paris) ; 55(3): 229-34, 1997.
Article in French | MEDLINE | ID: mdl-9238425

ABSTRACT

Results in enzymology obtained in routine conditions, differ considerably according to the measurement procedures, and the use of conversion factors is not an advisable solution. Some studies show that between-laboratory agreement of results can be improved by using validated enzyme calibrators. The conditions, which are required to define a strategy for the development of such calibrators, are described in a first part. The example of lipase activity, which is measured in routine conditions with important between-method discrepancy, is studied in a second part. This example emphasised the need of an a priori control of the validity of the calibrators. Under these conditions, between-method agreement is in fact considerably improved. With the collaboration of manufacturers for the development of validated enzyme multicalibrators, it will be possible to improve the efficiency of the information transmitted by clinical chemists to clinicians. Thus, enzyme activities measurements could benefit from the same improvement as immunoassay of proteins with the use of CRM 470 by manufacturers to calibrate their standards.


Subject(s)
Calibration/standards , Immunoenzyme Techniques/standards , Humans , Information Systems , Lipase/metabolism , Pancreas/enzymology , Patient Care Team
16.
Clin Chem ; 42(12): 1979-83, 1996 Dec.
Article in English | MEDLINE | ID: mdl-8969636

ABSTRACT

Comparability of lipase catalytic activities was poor when lipase was determined in 50 patients' specimens by a turbidimetric (Boehringer) and a colorimetric (Sigma) assay. Mean values of results differed by a ratio of 2.39. Optimal common conditions were defined for the titration of lipase activity in two commercial calibrators and in a home-purified preparation of human pancreatic lipase (HPL). When using these titers for each calibrator, comparability was greatly improved (ratio = 1.25). This result indicates that a significant part of between-method discrepancy is due to the lack of a reference method for the titration of lipase calibrators. Intermethod behavior of each material was compared with that of patients' specimens. By using HPL as calibrator, comparability was still dramatically improved (ratio = 1.01). This study shows the importance of the validation of a material for defined routine measurement procedures, before its use as calibrator.


Subject(s)
Colorimetry/standards , Lipase/blood , Nephelometry and Turbidimetry/standards , Calcium/pharmacology , Calibration , Catalysis , Colipases/pharmacology , Colorimetry/methods , Deoxycholic Acid/pharmacology , Humans , Hydrogen-Ion Concentration , Lipase/metabolism , Nephelometry and Turbidimetry/methods , Pancreas/enzymology
17.
Clin Chim Acta ; 251(2): 119-29, 1996 Jul 30.
Article in English | MEDLINE | ID: mdl-8862468

ABSTRACT

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.


Subject(s)
Lipase/metabolism , Pancreatic Juice/enzymology , Calcium/pharmacology , Catalysis , Cholagogues and Choleretics/pharmacology , Deoxycholic Acid/pharmacology , Emulsions , Freeze Drying , Humans , Hydrogen-Ion Concentration , Indicators and Reagents , Kinetics , Lipase/chemistry , Lipase/isolation & purification , Nephelometry and Turbidimetry , Olive Oil , Plant Oils/chemistry , Spectrophotometry, Ultraviolet
18.
Clin Chim Acta ; 251(2): 145-62, 1996 Jul 30.
Article in English | MEDLINE | ID: mdl-8862470

ABSTRACT

We describe the preparation of a lyophilized material containing purified human pancreatic alpha-amylase and the certification of its catalytic concentration. The enzyme was purified from human pancreas by ammonium sulphate precipitation and chromatography successively on DEAE-Sephacel, CM-Sepharose and Sephadex G-75. The purified enzyme had a specific activity of 52.9 kU/g protein and was > 99% pure on polyacrylamide gel electrophoresis. Only trace amounts of lipase and lactate dehydrogenase were detected in the purified fraction. The purified pancreatic alpha-amylase had a molar mass of 57,500 g/mol and an isoelectric point at 7.1. The material was prepared by diluting the purified alpha-amylase in a matrix containing PIPES buffer 25 mmol/l, pH 7.0, sodium chloride 50 mmol/l, calcium chloride 1.5 mmol/l, EDTA 0.5 mmol/l and human serum albumin 30 g/l, dispensing in ampoules and freeze-drying. The ampoules were homogeneous and the yearly loss of activity on the basis of accelerated degradation studies was less than 0.01% at -20 degrees C. The certified value for alpha-amylase catalytic concentration in the reconstituted reference material is 555 U/l +/- 11 U/l when measured by the specified method at 37 degrees C. The material can be used to verify the comparability of results from laboratories, for intra-laboratory quality control or for calibration of alpha-amylase catalytic concentration measurements.


Subject(s)
Pancreas/enzymology , alpha-Amylases/isolation & purification , Catalysis , Drug Stability , Electrophoresis, Polyacrylamide Gel , Freeze Drying , Humans , Hydrogen-Ion Concentration , Indicators and Reagents , Pancreas/chemistry , Reference Standards , Spectrophotometry, Ultraviolet , Time Factors , alpha-Amylases/chemistry
19.
Eur J Clin Chem Clin Biochem ; 33(11): 859-64, 1995 Nov.
Article in English | MEDLINE | ID: mdl-8620064

ABSTRACT

alpha-Amylase, alkaline phosphatase and gamma-glutamyltransferase were studied in a multicentre evaluation. Analyses were performed on different patient samples. Each enzyme was assayed in two different laboratories at both 30 and 37 degrees C, with widely used reagent kits and with the IFCC reference method (if in existence). Results differed considerably according to the measurement procedure. Data also showed that it was not possible to employ a constant conversion factor for one enzyme and different techniques between 30 and 37 degrees C. Calibration with three reference materials extensively improved the intermethod consistency for most of the tested measurement procedures. It was possible to transfer accuracy from the method used for the certification of the reference material to routine procedures, by using the reference material as calibrator. Temperature did not seem to be a crucial variable for the implement of the enzyme calibrator approach.


Subject(s)
Alkaline Phosphatase/analysis , Reference Standards , alpha-Amylases/analysis , gamma-Glutamyltransferase/analysis , Alkaline Phosphatase/blood , Animals , Humans , Laboratories/standards , Myocardium/enzymology , Pancreas/enzymology , Quality Control , Reagent Kits, Diagnostic , Reproducibility of Results , Swine , Temperature , alpha-Amylases/blood , gamma-Glutamyltransferase/blood
20.
Ann Biol Clin (Paris) ; 53(3): 147-54, 1995.
Article in French | MEDLINE | ID: mdl-7574101

ABSTRACT

We report here on the results of a multicenter study of three enzyme activities (gamma-glutamyltransferase, alkaline phosphatase and amylase). For each activity, measurements were performed in two laboratories on different series of patients' specimens under routine conditions, at 30 and 37 degrees C, with techniques frequently used in France and with the IFCC reference method, when it exists. For each technique, precision was acceptable, but results differed considerably according to the technique used. The study also showed that for different techniques it is not possible to use a single transformation factor for activities between 30 and 37 degrees C. Patients' results determined by two techniques often showed a constant relationship. Groups of techniques that determined the same catalytic activity in patients' specimens were identified, whereas other techniques did not have this property. Several preparations, including reference materials produced by the Community Bureau of Reference (European Community, Brussels) and ten commercial secondary materials were tested for similar behaviour as compared to patients' samples. Results show the commutability of reference materials within a group of techniques indicating that they can be used as calibrators. This was seldom the case for the commercial secondary materials and we did not find any such material suitable for calibration of the three enzymatic activities. The present study demonstrates that with defined techniques and validated calibrators it is possible to reduce considerably differences between results obtained with different techniques at different temperatures and in different laboratories.


Subject(s)
Alkaline Phosphatase/metabolism , Amylases/metabolism , Clinical Enzyme Tests/methods , gamma-Glutamyltransferase/metabolism , Calibration , Humans , Reference Values
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