A two-step strategy combining assisted benchmark testing (entry controls) and External Quality Assessments (EQAs) with blinded simulated clinical specimens to enhance and maintain the quality of ...nucleic acid amplification testing was developed. This strategy was successfully applied to 71 diagnostic laboratories in The Netherlands when upscaling the national diagnostic capacity during the SARS-CoV-2 pandemic. The availability of benchmark testing in combination with advice for improvement substantially enhanced the quality of the laboratory testing procedures for SARS-CoV-2 detection. The three subsequent EQA rounds demonstrated high quality testing with regard to specificity (99.6% correctly identified) and sensitivity (93.3% correctly identified). Even with the implementation of novel assays, changing workflows using diverse equipment and a high degree of assay heterogeneity, the overall high quality was maintained using this two-step strategy. We show that in contrast to the limited value of Cq value for absolute proxies of viral load, these Cq values can, in combination with metadata on strategies and techniques, provide valuable information for laboratories to improve their procedures. In conclusion, our two-step strategy (preparation phase followed by a series of EQAs) is a rapid and flexible system capable of scaling, improving, and maintaining high quality diagnostics even in a rapidly evolving (e.g. pandemic) situation.
We have investigated whether the Farr assay measures the primary interaction between DNA and anti-DNA. By the use of zonal centrifugation to analyse DNA/anti-DNA complexes and by a detailed study of ...the quantitative aspects of the Farr assay we demonstrate that: (a) binding of a single IgG molecule to a PM2 DNA molecule (molecular weight 5.9 X 10(6)) renders the latter precipitable in half-saturated ammonium sulphate; (b) two antibody molecules are required for precipitation of T7 DNA (molecular weight 25 X 10(6)); (c) millipore filtration detects binding of a single antibody molecule per molecule of PM2 DNA; (d) theoretically and experimentally the relation between free DNA (F) and the amount of serum (S) can be described by IfF =-cS where c is a constant; (e) it is feasable to quantitate serum anti-DNA activity in terms of units per ml.
DNA/anti-DNA complexes were studied by equilibrium density centrifugation in CsC1 and by zonal centrifugation in sucrose gradients. Complexes prepared of circular DNA preparations PM2 DNA or SV40 DNA ...with anti-DNA obtained from patients with systemic lupus erythematosus were found to be stable under the conditions of CsC1 equilibrium centrifugation. This enabled homogeneous complexes of DNA and anti-DNA of composition AgAb1, AgAb2, AgAb3 etc to be isolated. The stability of these complexes, their banding pattern in CsC1 gradients and their sedimentation behaviour suggest that anti-DNA binds to DNA in a monogamous bivalent way.
Human monocytes produce a number of soluble mediators involved in regulation of inflammation and lymphocyte growth and differentiation such as interleukin 1 (IL 1) and tumor necrosis factor. ...Recently, the cDNA of another monocyte-derived factor, interleukin 6 (IL 6), was cloned. Herein we show that purified E. coli-derived recombinant IL 6 (rIL 6) is as active as IL 1 in the thymocyte assay. In addition, IL 1 and IL 6 synergize strongly in stimulating thymocyte proliferation. Another property shared by IL 1 and IL 6 is their pyrogenicity. Human rIL 6 induces a monophasic fever after i.v. injection into rabbits. Together with the observation that IL 1 induces IL 6 in a variety of cells including thymocytes, our data suggest that IL 6 is involved in many of the pleiotropic effects of IL 1.
Abstract Background Children with an obstetric brachial plexus injury (OBPI) can experience problems in the performance of meaningful activities such as writing, bimanual activities, and ...participation in sports and leisure activities. Aims To quantify the everyday functioning and participation of 7–8 year-old children with an OBPI, with special emphasis on writing, and to investigate associated characteristics. Methods Parents of children with an OBPI were sent a self-report questionnaire regarding the school performance, writing abilities, bimanual hand use, and participation in sports and leisure activities of their child, assessed with the Vineland Adaptive Behavior Scales (VABS sub-scale writing), the ABILHAND-kids, and the Children’s Assessment of Participation and Enjoyment (CAPE). Furthermore, questions were asked about socio-demographic variables, medical history, pain, and the use of assistive devices. Results Fifty three questionnaires were filled in (response 61%). According to the parents, 66% of their children were almost completely recovered, and 58% had a near normal arm function. Most of the children preferred to use their non-involved hand. More than 45% of the children complained about pain, and 39.6% had difficulties with writing, which resulted in a mean developmental delay of 8 months on the VABS sub-scale. Children with writing problems significantly more often had neurosurgery, were living with a single parent, more often received assistance at school, and had a significantly lower ABILHAND-kids score, compared to children with no writing problems. Conclusions Large percentages of 7–8 year-old children with an OBPI experience difficulties with writing and have musculoskeletal pain. Restrictions in participation were less pronounced.
