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W Huisman

Publications and source records attributed to W Huisman.

At least 19 recordsLinked to original sources
PubMed2001

European Communities Confederation of Clinical Chemistry Working Group on Accreditation: past, present and future.

During the past 10 years, many activities have taken place in the field of quality systems and accreditation in medical laboratories. Each country in Europe has a slightly different approach. The Working Group on Accreditation of the European Communities Confederation of Clinical Chemistry (EC4) tries to support harmonisation of these efforts. For this purpose, they edited the Essential Criteria for quality systems of medical laboratories and supported the forthcoming International ISO standard "Quality management for the medical laboratory". At this moment, a Model Quality Manual is nearly ready for publication. The next items are setting up criteria for auditing the quality system and criteria for the accreditation process.

Accreditation↗
PubMed2000

Quantitative and qualitative analysis of haemoglobin variants using capillary zone electrophoresis.

Capillary zone electrophoresis (CZE) has been introduced into the clinical chemistry laboratory because of its range of potential applications. In this paper, we evaluate an alkaline CZE method for the quantification of HbA2 and HbF and also assess the combination of the alkaline CZE method with an acid CZE method for the determination of haemoglobin variants in an automated fashion. Correlation of the HbA2% determined between the HbA2-CZE method (alkaline conditions) and the Helena Sickle Thal Quick Column method was good (r = 0.91). The correlation between the HbF% determined by the HbA2-CZE method and by the alkaline denaturation method was acceptable (r = 0.81). The HbA2-CZE method was able to identify a large number of haemoglobin variants. The variants HbC and HbE or HbS and HbD, however, had the same characteristics under alkaline conditions and could therefore not be discriminated from each other. The identification of these overlapping variants could be accomplished by the analysis of the blood specimens in combination with the HbA1c-CZE method (acid conditions). We conclude that the presented applications for capillary zone electrophoresis can be used for quantitative and qualitative analysis of haemoglobin variants.

Chromatography, Liquid↗
PubMed2000

Usefulness of EC4 essential criteria for quality systems of medical laboratories as guideline to the ISO 15189 and ISO 17025 documents. European Community Confederation of Clinical Chemistry (EC4) Working Group on Harmonisation of Quality Systems and Accreditation.

Many medical laboratories have made a start with the introduction of quality management systems. However, it is still not clear against which standards such systems should be measured. The existing ISO and CEN standards do not cover essential aspects of medical laboratories. The publication of the EC4 Essential Criteria has stimulated the development of the ISO/Draft International Standard 15189. This standard seems adequate for our type of laboratories. However, it is not easy to read. The EC4 Essential Criteria could well serve as a guide, covering additional aspects, e.g. on total quality management and budget management as required in the EFQM model, that are not (yet) included in the ISO standard. In the present article the EC4 Essential Criteria are cross-referenced with two new international ISO standards, ISO/FDIS 15189 and ISO/FDIS 17025, the latter being the successor of ISO guide 25 and EN 45000. Both new ISO documents are in compliance with the new ISO 9000:2000 standard.

Europe↗
PubMed1999

Vaccination with experimental feline immunodeficiency virus vaccines, based on autologous infected cells, elicits enhancement of homologous challenge infection.

Cats were vaccinated with fixed autologous feline immunodeficiency virus (FIV)-infected cells in order to present viral proteins to the immune system of individual cats in an MHC-matched fashion. Upon vaccination, a humoral response against Gag was induced. Furthermore, virus-neutralizing antibodies were detected in a Crandell feline kidney cell-based neutralization assay, but not in a neutralization assay based on primary peripheral blood mononuclear cells. Despite the induction of these FIV-specific responses, vaccinated cats were not protected. Instead, accelerated virus replication was found, an observation similar to what previous experiments using other vaccine candidates have shown. Here, the results of the present study are discussed in the light of enhancement of lentivirus infections as a complicating factor in lentivirus vaccine development.

Animals↗
PubMed1998

Accelerated viraemia in cats vaccinated with fixed autologous FIV-infected cells.

We have vaccinated cats with fixed autologous FIV infected PBMC to determine whether autologous presentation of antigen is capable of inducing a protective immune response against homologous challenge. To this end autologous PBMC were infected with a FIV molecular clone (19k1). When infection was established, cells were inactivated by dialysis against paraformaldehyde. Upon vaccination, cats developed a virus specific immune response as measured by ELISA against the Gag protein of FIV. No antibodies against the envelope protein were detected with a peptide ELISA. Virus neutralizing antibodies however could be detected with a neutralization assay based on infection of CrFK cells, but not in an assay based on infection of primary T-cells. Although vaccination led to the induction of these virus-specific immune responses, vaccinated cats were not protected against homologous challenge but showed an accelerated viraemia upon infection. This was shown both by PCR and cell-associated viral load. The possible mechanisms underlying this observation are discussed in this paper.

Animals↗
PubMed1998

Additional Essential Criteria for Quality Systems of Medical Laboratories. European Community Confederation of Clinical Chemistry (EC4) Working Group on Harmonisation of Quality Systems and Accreditation.

Essential Criteria for Quality Systems of Medical Laboratories have been published recently by the European Community Confederation of Clinical Chemistry (EC4) Working Group on Harmonisation of Quality Systems and Accreditation. The Essential Criteria address the majority of critical aspects of quality management in the medical laboratory. They have been accepted by the EC4 General Assembly and are endorsed by the Forum of European Societies for Clinical Chemistry (FESCC). However, a supplement to the Essential Criteria was necessary, addressing two aspects, which are only partly covered by the Essential Criteria: the management of resources and point of care testing. Thus, the EC4 Working Group on Harmonisation of Quality Systems and Accreditation has decided to formulate Additional Essential Criteria for Quality Systems of Medical Laboratories, directed at the issues of management of resources and point of care testing. Criteria on management of resources address financial aspects, information logistics and acceptance by clients. Criteria on point of care testing address responsibilities, education of non-laboratory staff and operational aspects. The Additional Criteria are supplementary to the previously published Essential Criteria and should be read as an integral part of these.

Accreditation↗
PubMed1997

Salmonella typhimurium aroA recombinants and immune-stimulating complexes as vaccine candidates for feline immunodeficiency virus.

Two experimental feline immunodeficiency virus (FIV) vaccines were tested, either alone or in combination, in four groups of cats (A-D). One vaccine (SL3261-FIV) was composed of live attenuated Salmonella typhimurium aroA (SL3261) strains expressing the capsid (Gag) and part of the envelope (Env) proteins of FIV. The other was composed of FIV Gag and Env proteins incorporated into immune-stimulating complexes (iscom-FIV). Cats of group A were immunized four times with SL3261-FIV. Cats of group B were immunized twice with SL3261-FIV and then twice with iscom-FIV. Cats of group C were immunized twice with SL3261 expressing the B subunit of cholera toxin (SL3261-CtxB) and then twice with iscom-FIV. Cats of group D, which served as negative controls, were immunized twice with SL3261-CtxB and then twice with iscom into which the Gag and Env proteins of simian immunodeficiency virus (SIV) had been incorporated (iscom-SIV). Two weeks after the last immunization, all cats were challenged with FIV. At this time, cats immunized with iscom-FIV (groups B and C) showed strong plasma antibody responses to Gag and Env, whilst these responses were weak or undetectable in the cats immunized four times with SL3261-FIV (group A). Seven weeks after FIV challenge, Env-specific antibody responses had increased considerably in cats of all groups except group A. The mean virus loads in the cats of this group proved to be lower than those of the other groups at all time points, indicating partial protection.

Animals↗
PubMed1997

Essential criteria for quality systems in medical laboratories.

The introduction of total quality systems in medical and clinical laboratories and accreditation of these laboratories is gaining more and more interest. In several countries laboratories have set up quality systems, and accrediation schemes are also operating. The standards of these schemes have much in common although several differences exist. There exists uncertainty in several countries on the choice of a system. Laboratory specialists are confronted with a new way of thinking concerning the management and daily practice of their laboratories. It is not clear, which standards should be used as a basis, and certainly not how to interpret such standards. Particulary in the European Union, harmonisation of criteria for quality systems is desirable. In the present paper, the document entitled "Essential Criteria for Quality Systems in Medical Laboratories" is presented. The document has been accepted in the general Assembly of the European Communities Confederation of Clinical Chemistry (EC4) and by the working group on Good Laboratory Services of the European Council on Laboratory Medicine (ECLM). The criteria in the document are focussed on the particular situation of medical laboratories, including pre- and post-analytical aspects. Reference is made, where applicable, to EN 45001, ISO 9001 and ISO guide 25 draft 3.

Chemistry, Clinical↗
PubMed1996

Canine distemper virus from diseased large felids: biological properties and phylogenetic relationships.

Specific pathogen free (SPF) domestic cats were inoculated with tissue homogenate obtained from a Chinese leopard (Panthera pardus japonensis) that had died in a North American zoo from a natural infection with canine distemper virus (CDV). The cats developed a transient cell-associated CDV viraemia along with pronounced lymphopenia but did not show any clinical symptoms. Plasma neutralizing-antibody titres against the homologous CDV (A92-27/4, isolated from the Chinese leopard) were consistently higher than against the CDV vaccine strain 'Bussell'. The Chinese leopard CDV isolate showed in vitro biological properties reminiscent of virulent, wild-type CDV strains. Sequence analysis of the H gene of two large felid CDV isolates from the USA (A92-27/4 and A92-6) revealed up to 10% amino acid changes including up to four additional potential N-linked glycosylation sites in the extra-cytoplasmic domain as compared to CDV vaccine strains. Phylogenetic analysis was performed using the entire coding region of the H gene and a 388 bp fragment of the P gene of several morbillivirus species. Evidence was obtained that recent CDV isolates from different species in the United States (including isolates from large felids), Europe and Africa are significantly distinct from CDV vaccine strains. All wild-type CDV isolates analysed clustered according to geographical distribution rather than to host species origin. By sequence analysis a CDV epizootic among large felids in a Californian safari park was linked to a virus which most likely originated from feral non-felid carnivores.

Amino Acid Sequence↗
PubMed1995

Enhancement of feline immunodeficiency virus infection after immunization with envelope glycoprotein subunit vaccines.

Cats were immunized three times with different recombinant feline immunodeficiency virus (FIV) candidate vaccines. Recombinant vaccinia virus (rVV)-expressed envelope glycoprotein with (vGR657) or without (vGR657 x 15) the cleavage site and an FIV envelope bacterial fusion protein (beta-Galactosidase-Env) were incorporated into immune-stimulating complexes or adjuvanted with Quil A. Although all immunized cats developed antibodies against the envelope protein, only the cats vaccinated with the rVV-expressed envelope glycoproteins developed antibodies which neutralized FIV infection of Crandell feline kidney cells. These antibodies failed to neutralize infection of thymocytes with a molecularly cloned homologous FIV. After the third immunization the cats were challenged with homologous FIV. Two weeks after challenge the cell-associated viral load proved to be significantly higher in the cats immunized with vGR657 and vGR657 x 15 than in the other cats. The cats immunized with vGR657 and vGR657 x 15 also developed antibodies against the Gag proteins more rapidly than the cats immunized with beta-Galactosidase-Env or the control cats. This suggested that immunization with rVV-expressed glycoprotein of FIV results in enhanced infectivity of FIV. It was shown that the observed enhancement could be transferred to naive cats with plasma collected at the day of challenge.

Animals↗
PubMed1995

Neutralization of feline immunodeficiency virus by polyclonal feline antibody: simultaneous involvement of hypervariable regions 4 and 5 of the surface glycoprotein.

Sites involved in antibody-mediated neutralization of feline immunodeficiency virus were mapped by reciprocal exchange of envelope fragments or amino acids between molecular clones of feline immunodeficiency virus with different susceptibilities to neutralization by a polyclonal cat serum. Combinations of mutations within HV-4 or within HV-4 and HV-5 changed the susceptibility of the viruses to neutralizing antibody.

Animals↗
PubMed1995

Quality and accreditation systems in clinical biochemistry in the European Union.

The European Community Confederation of Clinical Chemistry (EC4) formed in Nice in April 1993 has established a working group on laboratory accreditation. The aim of the group is to explore the possibilities for harmonisation of accreditation and quality systems in clinical laboratories in the European Community (EC). It is felt essential that professions should play a key role in the process, and that the principle of subsidiarity should be observed in relation to implementation and organisation in individual member states. The first task has been to collect information concerning such systems. In September 1993 a questionnaire was distributed to the twelve IFCC related societies for clinical chemistry in the EC. By December 1994 eleven societies had responded. The questionnaire related to the existence or planned introduction of quality and accreditation systems, the basis of the standards used and requirements for analytical aspects and qualifications of staff as well as professional aspects. Questions also addressed the way in which inspection were organised, the selection and training of inspectors, the organisation of systems and what interest there was in harmonisation. The results of this study are presented in this paper.

Accreditation↗
PubMed1994

Quality system in the medical laboratory: the role of a quality manual.

A quality system for a medical laboratory should be directed on all fundamental aspects of its function. This implies the obligation to join the External Quality Assessment schemes, and to make use of its results. It means the setting-up of a quality system according to a medical translation of the items of the EN 45001 standard. And it means taking into account such professional aspects as registration and post-doctoral education, regular contacts with physicians and paying special attention to the suitability of tests. This whole process can be instituted on the basis of an ISO 9000 approach, which means specific standards for the medical laboratories, and inspection, in which the professionals should play an important role. The use of a quality manual facilitates the whole process. It should eventually lead to an accreditation system for medical laboratories. Cooperation in Europe on these aspects is important. An overview is given on the way the system works in the Netherlands.

Europe↗
PubMed1983

Formulation of a stable vidarabine infusion fluid.

Decomposition of vidarabine in a 5% glucose infusion fluid after steam sterilization was measured by HPLC and TLC analysis. After sterilization for 60 minutes at 100 degrees C and 20 minutes at 120 degrees C no degradation could be observed. A slight but significant degradation was observed after sterilization for 60 minutes at 120 degrees C followed by storage for eight months. Assuming 5% loss of content to be acceptable, it was concluded that a vidarabine infusion fluid can be sterilized for 20 minutes at 120 degrees C and stored at room temperature for at least eight months afterwards.

Adenine↗
PubMed1982

Unstable glycosylated hemoglobin in patients with diabetes mellitus.

Incubation of washed erythrocytes for 4 h at 37 degrees C in saline resulted in the disappearance of an unstable glycosylated fraction. In a reference group, its amount was very small, but its presence had a significant influence on the upper level of the reference range. In non-diabetic pregnant women, the unstable fraction was significantly higher than in the non-pregnant individuals, which resulted in a lower reference range for the stable HbA1. In diabetic patients, the average unstable HbA1 was about 10% of the "unincubated" level, with marked differences between individuals (0--30%), even in patients with a slightly elevated HbA1. Therefore it is important to determine the concentration of stable HbA1.

Diabetes Mellitus↗