Recommendations for the application and follow-up of quality controls in medical laboratories

This is a translation of the paper “Recommendations for the application and follow-up of quality controls in medical biology laboratories” published in French in the journal Annales de Biologie Clinique (Recommandations pour la mise en place et le suivi des contrôles de qualité dans les laboratoires de biologie médicale. Ann Biol Clin (Paris). 2019;77:577-97.). The recommendations proposed in this document are the result of work conducted jointly by the Network of Accredited Medical Laboratories (LABAC), the French Society of Medical Biology (SFBC) and the Federation of Associations for External Quality Assessment (FAEEQ). The different steps of the implementation of quality controls, based on a risk analysis, are described. The changes of reagent or internal quality control (IQC) materials batches, the action to be taken in case of non-conform IQC results, the choice of external quality assessment (EQA) scheme and interpretation of their results as well as the new issue of analyses performed on several automatic systems available in the same laboratory are discussed. Finally, the concept of measurement uncertainty, the robustness of the methods as well as the specificities of near-patient testing and rapid tests are described. These recommendations cannot apply for all cases we can find in medical laboratories. The implementation of an objective alternative strategy, supported with documented evidence, might be equally considered

Influence of seawater exchanges across the Bab-el-Mandeb Strait on sedimentation in the Southern Red Sea during the last 60 ka

International audience[1] The location of core MD92-1008 close to the southern edge of the Red Sea is ideal to study the evolution of seawater exchanges with the Northern Indian Ocean through the Bab-el-Mandeb narrow strait. The present study was aimed at documenting the paleoceanographic evolution of this area over the past 60 ka using high-resolution magnetic, sedimentological, and geochemical indicators. Two modes of variability dominate the records: (i) long-term, glacial-interglacial variations and (ii) rapid, millennial scale variability (Dansgaard-Oeschger type) during the last glacial period. Changes in magnetic concentration were documented from natural and laboratory magnetizations after proper normalization. They are inversely correlated to the total organic carbon (TOC) content, pointing out the key role played by reductive dissolution of magnetite on the evolution of magnetic concentration. Based on the temporal evolution of TOC, CaCO 3 , and planktonic δ 13 C, we suggest that past changes in the organic matter content (i) were closely linked to glacio-eustatic variations which modulated long-term seawater exchanges and nutrient supplies to the Red Sea through the narrow Bab-el-Mandeb Strait and (ii) reflect millennial-scale changes in productivity driven by monsoon wind intensity which controlled the amount of nutrient-rich intermediate waters upwelled in the Gulf of Aden during the summer season and advected into the Southern Red Sea. The sea level rise following the onset of deglaciation generated a rapid flush of detrital material that was accumulated on the continental margins and on the previously emerged zones of the Bab-el-Mandeb area. Influence of seawater exchanges across the Bab-el-Mandeb Strait on sedimentation in the Southern Red Sea during the last 60 ka, Paleoceanography, 28, 675-687

Diagenetic modulation of the magnetic properties in sediments from the Northern Indian Ocean

Large changes in magnetic mineral concentration dependent parameters by more than 1 order of magnitude occur over 50-150 cm intervals in two marine sediment cores from the oxygen minimum zone in the Gulf of Aden. High-resolution sedimentological and chemical analyses indicate that these intervals are not associated with turbiditic events or sediment reworking, they do not result from changes in carbonate dilution or differences in sediment properties, and they do not correspond to volcanic layers. Magnetic mineralogical analyses reveal a change in magnetic mineral concentration from a magnetite-goethite assemblage to pure magnetite within the peak. The peaks almost disappear when the abundance of magnetic minerals is calculated after correcting for the magnetic moments of each magnetic mineral. Therefore, under the assumption that the variability of the magnetic parameters results from postdepositional mineralogical transformations, a relatively constant amount of magnetite was present at the surface of the sediment. Changes in redox conditions and nonsteady state diagenesis transformations have effectively been observed along both cores. Large values of total organic carbon coincide with poor preservation of biogenic and detrital magnetite, which reflects reductive dissolution of the finer magnetite grains. At the same levels, Fe2+ release from reductively dissolved magnetite favored precipitation of goethite. The susceptibility peaks coincide with episodes of magnetite preservation caused by reduced surface productivity and/or enhanced bottom-water ventilation accompanying northward extension of Glacial Antarctic Intermediate Water into the Indian Ocean

Dyserythropoiesis evaluated by the RED score and hepcidin:ferritin ratio predicts response to erythropoietin in lower-risk myelodysplastic syndromes

International audienceErythropoiesis-stimulating agents are generally the first line of treatment of anemia in patients with lower-risk myelodysplastic syndrome. We prospectively investigated the predictive value of somatic mutations, and biomarkers of ineffective erythropoiesis including the flow cytometry RED score, serum growth-differentiation factor-15, and hepcidin levels. Inclusion criteria were no prior treatment with erythropoiesis-stimulating agents, low- or intermediate-1-risk myelodysplastic syndrome according to the International Prognostic Scoring System, and a hemoglobin level 4 (P=0.05) and a hepcidin:ferritin ratio 2000 pg/mL and a hepcidin:ferritin ratio <9 (P=0.0008 and P=0.01, respectively). In multivariate analysis, both variables were associated with shorter response duration. Erythroid response to epoetin zeta was similar to that obtained with other erythropoiesis-stimulating agents and was correlated with higher baseline hepcidin:ferritin ratio and lower RED score. ClinicalTrials.gov registration: NCT 03598582