[Description of the processes involved in the control of point-of-care testing]. / Description des processus impliqués dans la maîtrise des examens de biologie médicale délocalisés.

Compliance to EN ISO 22870 standard for point-of-care testing (POCT) accreditation is close to those of EN ISO 15189 in central laboratory. However, it is mandatory to master the elements which are specific to POCT. In this paper, we describe the two main processes involved to help medical biologists to achieve standard requirements, particularly in the risk assessment study. The first process concerns the deployment of a POCT device in a hospital outside laboratory and the second is the classical process of medical biology testing, outlining the steps which are different from the laboratory testing process. Furthermore, we reference, in front of each sub-process described, the different articles published in the present volume detailing specific guidelines to master them.

[Guidelines for the formation of a multidisciplinary group for point-of-care testing supervision according to EN ISO 22870]. / Recommandations pour la constitution d'un groupe d'encadrement des examens de biologie médicale délocalisés.

EN ISO 22870 requires the medical laboratory director to form a multidisciplinary group for the management of point-of-care testing activities and to appoint a person responsible for this group. This article proposes to define the composition (representatives of the medical laboratory, care units owning point-of-care devices, administration), missions (introduction, follow-up and evaluation of point-of-care devices) and the decision circuit of this group and to describe the profile of the head and the tasks assigned.

[Guidelines for selection and implementation of a point-of-care testing device according to the EN ISO 22870 and French regulation]. / Recommandations pour le choix et la mise en place d'un dispositif de biologie médicale délocalisé.

Implementation is the main step of the point-of-care testing (POCT) device installation process to comply with EN ISO 22870. The multidisciplinary POCT management group is in charge to align that process with the standards but also with the French regulation (ordinance 2010-49 of 13 January 2010) which authorizes POCT only in case of urgent therapeutic decisions. This article defines two reports to be prepared during the deployment of a POCT device : a report that justifies the use of a POCT device, taking into account a risk-benefit analysis and a report that justifies the choice of the device including proofs of conformity of its installation.

[Guidelines for point-of-care testing quality management according to ISO 22870]. / Recommandations pour la mise en place d'un système de management de la qualité des examens de biologie médicale délocalisés.

In this paper, we focus on the additional requirements of EN ISO 22870 compared to those described in Chapter 4: Quality Management of EN ISO 15189. They concern the quality policy, the management reviews and the audits. Thus, we propose a template of quality policy statement, and specific requirements for conducting management review of POCT are given. Finally, a questionnaire for performing an audit of POCT activities is proposed. The composition and activities of the multidisciplinary group for the supervision of POCT activities, which is also a specific requirement of EN ISO 22870, is discussed in another article of this volume.

[Guidelines for the management of point-of care testing pre-examination, examination and post-examination phases according to the EN ISO 22870 standard]. / Recommandations pour la maîtrise des phases pré-analytique et analytique des examens de biologie médicale délocalisés.

Quality of point-of-care examinations depends on the quality assurance system settled. This paper describes the different tools used to control the pre-examination, examination and post-examination procedures taking part in the quality of patient care according to the requirements of the standard EN ISO 22870 and EN ISO 15189 as well. They include mainly: For the pre-examination phase, the sample traceability and for the analytical phase, the practice of internal quality control and the participation in external quality assessment programme.

[Guidelines for the management of point-of care testing nonconformities according to the EN ISO 22870]. / Recommandations pour la gestion des non-conformités des examens de biologie médicale délocalisés.

In this paper, guidelines are proposed to fulfill the requirements of EN ISO 22870 standard regarding the management of point-of-care testing (POCT) nonconformities. In the first part, the main nonconformities that may affect POCT are given, the means for resolution and the control of adverse events are proposed. In the second part, we propose recommendations in case of unavailability of a point-of-care testing device from the occurring of the adverse event, to the restarting of the device.

[Guidelines for the order process of medical laboratory tests]. / Outils pour l'élaboration et la gestion des formulaires de demande d'examens de biologie médicale.

This document presents the requirements enumerated in the ISO 15189 standard to make reliable the formulation of a medical laboratory test order. The contents and the filling conditions of the request laboratory tests form are described, to clarify the interest of the information required. The purpose is to help to construct a specific formulation allowing the adequate realization of the laboratory tests but also to collect the needed clinical information essential to allow a relevant interpretation of the results with a goal of improvement of patient care. We present also the main forms required for special laboratory tests, particularly concerning the human genome. Finally, the criteria to be reviewed at the entry of the laboratory (contract review) during the request acceptation before its registration are enumerated.

Specific interaction of Aspergillus fumigatus with fibrinogen and its role in cell adhesion.

Interaction between Aspergillus fumigatus conidia and different proteins known to mediate the attachment of malignant tumor cells or microorganisms to the host tissues was studied in vitro. Flow cytometry using fluorescein isothiocyanate-conjugated fibrinogen confirmed that binding of human fibrinogen to the conidia was dose dependent and specific. Binding was inhibited by unlabeled fibrinogen and by basement membrane laminin. Moreover, the expression of fibrinogen receptors at the surfaces of conidia seemed to be related to the maturation of the conidia. Binding sites appeared to be located in the D domains of the fibrinogen molecule. However, the peptide sequence recognized by the fungus could not be identified but was different from the classical adhesive recognition sequences, RGDS and fibrinogen gamma-chain dodecapeptide. In addition, an assay of adherence to proteins immobilized onto microtiter plates allowed us to establish the role of these interactions in fungal adhesion. Conidia strongly adhered to human fibrinogen and to laminin but not to fibronectin. Adhesion to fibrinogen substrates was specific, since it was inhibited by soluble fibrinogen and by specific antibodies, and seemed to be mediated by the D domains of the molecule. Study of the adhesion of numerous strains or clinical isolates to various mammalian fibrinogens did not reveal any particular affinity of strains for some animal species. Finally, by cultivation of the fungus in the presence of 125I-human fibrinogen and analysis of the radiolabeled material bound to the surface of the fungus, we were able to specify the sequence of events allowing its installation within the host. The interactions identified here may play an important role in governing fungal adherence and host tissue invasion.

Purification and characterization of a fibrinogenolytic serine proteinase from Aspergillus fumigatus culture filtrate.

A fibrinogenolytic proteinase has been isolated from Aspergillus fumigatus culture filtrate by ammonium sulfate precipitation followed by successive chromatographies on Sephadex G-75 and immobilized phenylalanine. The purified proteinase exhibited a molecular weight of about 33 kDa. When analysed by SDS-polyacrylamide gels containing co-polymerized fibrinogen, the proteinase appeared as a broad band at the top of the gels, which could correspond to polymerization of the enzyme, as suggested by SDS-PAGE analysis of the unboiled eluate. The isoelectric point was 8.75 and the enzyme was not glycosylated. Proteinase activity was optimum at pH 9 and between 37 and 42 degrees C, although a decrease in activity was observed above 37 degrees C. PMSF and chymostatin markedly inhibited the proteinase activity, and good kinetic constants were obtained for the synthetic substrate, N-Suc-Ala-Ala-Pro-Phe-pNA. These results provide direct evidence that this enzyme belongs to the chymotrypsin-like serine proteinase group.

Specific binding of human fibrinogen fragment D to Aspergillus fumigatus conidia.

The interaction of purified human fibrinogen with Aspergillus fumigatus conidia was investigated by immunofluorescence and electron microscopy and binding assays with radiolabeled proteins. We described the localization of the binding sites on the A. fumigatus conidia and on the fibrinogen molecule and determined the binding characteristics. Immunofluorescence revealed that the fixation of purified fibrinogen was selectively associated with conidia and suggested a role for the D domains of the fibrinogen molecule. Binding assays performed with 125I-radiolabeled proteins confirmed that binding sites were located specifically in the D domains. No reaction could be detected with fragment E. The binding of 125I-fragment D to conidia was time dependent, saturable, and specific. Scatchard analysis of the data revealed an average of 1,200 binding sites per conidium, and an apparent dissociation constant (Kd) of 2.2 x 10(-9) M was estimated. Pretreatment of the cells with proteolytic enzymes or heat abolished binding, demonstrating the protein nature of the binding sites. Ultrastructural localization of the fungal receptors was determined by transmission electron microscopy. Labeling appeared to be associated with the outer electron-dense layer of the conidial wall and progressively decreased during the germination process. Labeling of thin sections with fragment D and an antifibrinogen immune serum revealed that binding sites also lay in the inner part of the wall and in vacuoles. These results indicate the presence at the conidial surface of specific receptors for fibrinogen which could act as mediators of conidial adherence to host tissues.

Fungal cell adhesion molecules in Candida albicans.

Adherence of Candida albicans to host tissues is considered a crucial step in the pathogenesis of candidiasis. Using in vitro assays, it was demonstrated that the yeast-mycelium transition was an important phenomenon in the acquisition of adhesive properties. Proteins with MWs of 60, 68, 200 and greater than 200 kDa seemed to be involved in germ tube adherence to plastic surfaces. Likewise, recent investigations have revealed that C. albicans expresses on its surface receptors which interact with a wide variety of host proteins, particularly some extracellular matrix components like fibronectin, laminin and collagen. Plasmatic components, such as fibrinogen, iC3b and C3d, have also been proposed as mediators of adherence of C. albicans. Thus, by their reaction with laminin, fibrinogen and C3d, the mannoproteins of 68 and 60 kDa demonstrated multiple biological activities. Proteins of similar MWs were detected as C3d and iC3b receptors, the latter showing similarities with the neutrophil CR3. Based upon the antigenic, structural and functional homologies between the candidal receptors and mammalian integrins, it was postulated that these fungal cell adhesion molecules (F-CAM) are members of the integrin family. Interactions with host proteins and molecular mimicry of mammalian adhesion molecules may be a fertile area for further research.

Structures involved in the binding of human fibrinogen to Candida albicans germ tubes.

Recent evidence for the interaction between human fibrinogen and Candida albicans germ tubes have led us to attempt to characterize the structures involved. Using 125I-radiolabeled proteins, fibrinogen purified by affinity chromatography and its plasmin degradation products, the binding sites on the fibrinogen molecule appeared to be located specifically in the D-domain. Conversely to the fibrinogen and the fragment D, radiolabeled fragment E, however, did not interact with cells. The binding was time-dependent, saturable and reversible. Scatchard analysis of the data obtained revealed an average of 6000 binding sites per germ tube with dissociation constant (Kd) of 5.2 X 10(-8) M. No potent competition was observed for a range of different proteins and carbohydrates. Fibrinogen fragment D binding proteins were identified using a dithiothreitol-iodoacetamide extract of the fungus. By sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western blotting, one component of 68 kDa was detected. Thus, the presence of fibrinogen binding proteins specifically localized on the cell wall surface of C. albicans germ tubes may constitute one of the factors involved in the development of candidosis.

Laminin receptors on Candida albicans germ tubes.

Recent evidence for the role of laminin in cell adhesion and in the pathogenesis of several bacterial infections has led us to investigate the existence of receptors for this extracellular matrix component in Candida albicans. At first, immunofluorescence demonstrated the presence of laminin-binding sites at the surface of germ tubes. Electron microscopy confirmed this result and permitted precise localization of the binding sites on the outermost fibrillar layer of the germ tube cell wall. By using 125I-radiolabeled laminin, the binding was shown to be saturable and specific, hence demonstrating characteristics of true receptors. Analysis of the data by the Scatchard equation indicated that there were about 8,000 binding sites per cell, with a dissociation constant (Kd) of 1.3 x 10(-9) M. Binding was inhibited by prior heating or trypsinization of cells. Furthermore, of the different proteins and carbohydrates tested in competition experiments, only fibrinogen greatly reduced the laminin binding. Finally, dithiothreitol and iodoacetamide treatment of germ tubes allowed us to identify the laminin receptors through analysis of this extract by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western immunoblotting. Two components, of 68 kilodaltons and a doublet of 60 and 62 kilodaltons, were detected. Thus, C. albicans possesses germ tube-specific surface receptors for laminin which could mediate its attachment to basement membranes and so contribute to the establishment of candidiasis.