Preventive plasmapheresis for rituximab related flare in cryoglobulinemic vasculitis.

Introduction: Rituximab monotherapy represents the main therapeutic option for cryoglobulinemic vasculitis (CV) with severe organ involvement. However, initial worsening of the CV, known as rituximab-associated CV flare (=CV flare), has been described and are associated with high mortality rates. The aim of the present study is to evaluate the outcomes of plasmapheresis initiated before or during rituximab treatment, as prevention of CV flare. Methods: We conducted a retrospecttive study in our tertiary referral center from 2001 to 2020. We have included all patients with CV receiving rituximab and divided them in two groups whether they had flare prevention by plasmapheresis or not. We evaluated rituximab-related CV flare incidence in both groups. CV flare was defined as the onset of a new organ involvement or worsening of the initial manifestations within 4 weeks following rituximab. Results: Among the 71 patients included, 44 received rituximab without plasmapheresis (control = CT cohort) and 27 received plasmapheresis before or during rituximab treatment (preventive plasmapheresis = PP cohort). PP was given to patients thought to have a high risk of CV flare, with significantly more severe diseases than patients in the CT cohort. Despite this, no CV flare was observed in the PP group. In the other hand, 5 flares occurred in the CT cohort. Conclusion: Our results show that plasmapheresis is efficient and well tolerated to prevent rituximab-associated CV flare. We believe that our data support the use of plasmapheresis in this indication, especially in patients with high risk of CV flare.

Formative Assessment of Diagnostic Testing in Family Medicine with Comprehensive MCQ Followed by Certainty-Based Mark.

INTRODUCTION: The choice of diagnostic tests in front of a given clinical case is a major part of medical reasoning. Failure to prescribe the right test can lead to serious diagnostic errors. Furthermore, unnecessary medical tests are a waste of money and could possibly generate injuries to patients, especially in family medicine. METHODS: In an effort to improve the training of our students to the choice of laboratory and imaging studies, we implemented a specific multiple-choice questions (MCQ), called comprehensive MCQ (cMCQ), with a fixed and high number of options matching various basic medical tests, followed by a certainty-based mark (CBM). This tool was used in the assessment of diagnostic test choice in various clinical cases of general practice in 456 sixth-year medical students. RESULTS: The scores were significantly correlated with the traditional exams (standard MCQ), with matched themes. The proportion of "cMCQ/CBM score" variance explained by "standard MCQ score" was 21.3%. The cMCQ placed students in a situation closer to practice reality than standard MCQ. In addition to its usefulness as an assessment tool, those tests had a formative value and allowed students to work on their ability to measure their doubt/certainty in order to develop a reflexive approach, required for their future professional practice. CONCLUSION: cMCQ followed by CBM is a feasible and reliable evaluation method for the assessment of diagnostic testing.

B cells response directed against Cut4 and CFP21 lipolytic enzymes in active and latent tuberculosis infections.

BACKGROUND: Better understanding of the immune response directed against Mycobacterium tuberculosis (Mtb) is critical for development of vaccine strategies and diagnosis tests. Previous studies suggested that Mtb enzymes involved in lipid metabolism, are associated with persistence and/or reactivation of dormant bacilli. METHODS: Circulating antibodies secreting cells (ASCs), memory B cells, and antibodies directed against Cut4 (Rv3452) and CFP21 (Rv1984c) antigens were explored in subjects with either active- or latent-tuberculosis (LTB), and in Mtb-uninfected individuals. RESULTS: Circulating anti-Cut4 ASCs were detected in 11/14 (78.6%) subjects from the active TB group vs. 4/17 (23.5%) from the LTB group (p = 0.001). Anti-CFP21 ASCs were found in 11/14 (78.6%) active TB vs. in 5/17 (29.4%) LTB cases (p = 0.01). Circulating anti-Cut4 and anti-CFP21 ASCs were not detected in 38 Mtb uninfected controls. Memory B cells directed against either Cut4 or CFP21 were identified in 8/11 (72.7%) and in 9/11 (81.8%) subjects with LTB infection, respectively, and in 2/6 Mtb uninfected individuals (33.3%). High level of anti-Cut4 and anti-CFP21 IgG were observed in active TB cases. CONCLUSION: Circulating IgG SCs directed against Cut4 or CFP21 were mostly detected in patients presenting an active form of the disease, suggesting that TB reactivation triggers an immune response against these two antigens.

Performance of two real-time PCR assays for hepatitis B virus DNA detection and quantitation.

In-house developed real-time PCR (qPCR) techniques could be useful conjunctives to the management of hepatitis B virus (HBV) infection in resource-limited settings with high prevalence. Two qPCR assays (qPCR1 and qPCR2), based on primers/probes targeting conserved regions of the X and S genes of HBV respectively, were evaluated using clinical samples of varying HBV genotypes, and compared to the commercial Roche Cobas AmpliPrep/Cobas TaqMan HBV Test v2.0. The lower detection limit (LDL) was established at 104 IU/ml for qPCR1, and 91 IU/ml for qPCR2. Good agreement and correlation were obtained between the Roche assay and both qPCR assays (r = 0.834 for qPCR1; and r = 0.870 for qPCR2). Differences in HBV DNA load of > 0.5 Log10 IU/ml between the Roche and the qPCR assays were found in 49/122 samples of qPCR1, and 35/122 samples of qPCR2. qPCR1 tended to underestimate HBV DNA quantity in samples with a low viral load and overestimate HBV DNA concentration in samples with a high viral load when compared to the Roche test. Both molecular tools that were developed, used on an open real-time PCR system, were reliable for HBV DNA detection and quantitation. The qPCR2 performed better than the qPCR1 and had the additional advantage of various HBV genotype detection and quantitation. This low cost quantitative HBV DNA PCR assay may be an alternative solution when implementing national programmes to diagnose, monitor and treat HBV infection in low- to middle-income countries where testing for HBV DNA is not available in governmental health programmes.

High-affinity uranyl-specific antibodies suitable for cellular imaging.

Monoclonal antibodies (mAbs) have proved to be valuable models for the study of protein-metal interactions, and previous reports have described very specific antibodies to chelated metal ions, including uranyl. We raised specific mAbs against UO2(2+)-DCP-BSA (DCP, 1,10-phenanthroline-2,9-dicarboxylic acid) to generate new sets of antibodies that might cross-react with various complexed forms of uranyl in different environments for further application in the field of toxicology. Using counter-screening with UO2(2+)-DCP-casein, we selected two highly specific mAbs against uranyl-DCP ( K D 10-100 pM): U04S and U08S. Competitive assays in the presence of different metal ions (UO2(2+), Fe (3+), Zn2+, Cu2+, and Ca2+) showed that uranyl in solution can act as a good competitor, suggesting some antibody ability to cross-react with chelating groups other than DCP in the UO2(2+) equatorial coordination plane. Interestingly, one of the antibodies could be used for revealing uranyl cations in cell samples. Fluorescence activated cell sorting analyses after immunolabeling revealed the interaction of uranyl with human kidney cells HK2. The intracellular accumulation of uranyl could be directly visualized by metal-immunostaining using fluorescent-labeled mAb. Our results suggest that U04S mAb epitopes mostly include the uranyl fraction and its paratopes can accommodate a wide variety of chelating groups.

Consequences of the bleed-through phenomenon in immunofluorescence of proteins forming radiation-induced nuclear foci.

PURPOSE: By allowing the visualization of the proteins inside cells, the immunofluorescence technique has revolutionized our view of events that follow radiation response. Particularly, the formation of nuclear foci, their kinetic of appearance and disappearance, and the association-dissociation of protein partners are useful endpoints to better understand the effects of ionizing radiation. Recently, the technique based on the phosphorylation of the histone 2A family, member X (H2AX) has generated a plethora of reports concerning the interaction between the major proteins involved in DNA repair and stress signaling pathways. However, some unavoidable overlaps of excitation and emission wavelength spectra (the so-called bleed-through phenomenon) of the available fluorescent markers are still generating discrepancies and misinterpretations in the choreography of DNA damage response. Biases are particularly strong with the fluorescein isothiocyanate (FITC)-rhodamine couple, tetramethyl rhodamine iso-thiocyanate (TRITC), the most extensively used markers. METHOD AND RESULTS: Here, two representative examples of biased co-immunofluorescence with pH2AX proteins that form radiation-induced nuclear foci or not are presented. A brief review of literature points out differences in kinetic of appearance and association-dissociation of radiation-induced pH2AX and MRE11 foci. CONCLUSION: Through this report, we would like authors to consider more carefully protein co-localizations by performing systematically, before any co-immunofluorescence, immunofluorescence of each protein separately to avoid bleed-through artifacts.