Individual cell-by-cell quantitation of lymphocyte surface membrane Ig in normal and CLL lymphocyte and during ontogeny of mouse B lymphocytes by immunoperoxidase assay

A new quantitative immunoperoxidase method is presented for determining absolute amounts of peroxidase and, consequently, surface antigen densities of individual cells in B lymphocytes from normal individuals, from subjects with CLL and prolymphocytic leukemia, and during ontogeny of B lympocytes in the mouse. The following results were observed: (1) The density of B antigenic sites were lower on CLL than on normal B lymphocytes. (2) The B antigens density of leukemic lymphocytes varied less from cell to cell, forming a homogeneous peak on histograms. (3) In a very rare case of CLL, the antigen density was measured at the time of initial diagnosis (22,500 sites or 647 U) and during the development of a blastic crisis (135,000 sites or 2576 U). The cell by cell distribution changed from a homogeneous peak with a low number of antigenic sites per cell to a heterogeneous peak with a high number of antigenic sites per cell. (4) In prolymphocytic leukemia, the density of B antigenic sites was greater than on normal B lymphocytes and much more heterogeneous than on CLL lymphocytes. (5) During ontogeny of B lymphocytes in the mouse, maturation is associated with the appearance of a population of cells of intermediate to high Smig density. The finding of a decrease in, and altered distribution of, surface markers in CLL is compared with these ontologic findings in the mouse, and the concept that a monoclonal B lymphocyte in CLL may be arrested at a particular stage in its differentiation is discussed.     

Evaluation of lockdown effect on SARS-CoV-2 dynamics through viral genome quantification in waste water,Greater Paris,France, 5 March to 23 April 2020

IntroductionSevere acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the etiological agent of coronavirus disease (COVID-19). People infected with SARS-CoV-2 may exhibit no or mild non-specific symptoms; thus, they may contribute to silent circulation of the virus among humans. Since SARS-CoV-2 RNA can be detected in stool samples, monitoring SARS-CoV-2 RNA in waste water (WW) has been proposed as a complementary tool to investigate virus circulation in human populations.AimTo test if the quantification of SARS-CoV-2 genomes in WW correlates with the number of symptomatic or non-symptomatic carriers.MethodWe performed a time-course quantitative analysis of SARS-CoV-2 by RT-qPCR in raw WW samples collected from several major WW treatment plants in Greater Paris. The study period was 5 March to 23 April 2020, including the lockdown period in France (from 17 March).ResultsWe showed that the increase of genome units in raw WW accurately followed the increase of human COVID-19 cases observed at the regional level. Of note, the viral genome could be detected before the epidemic grew massively (around 8 March). Equally importantly, a marked decrease in the quantities of genome units was observed concomitantly with the reduction in the number of new COVID-19 cases, 29 days following the lockdown.ConclusionThis work suggests that a quantitative monitoring of SARS-CoV-2 genomes in WW could generate important additional information for improved monitoring of SARS-CoV-2 circulation at local or regional levels and emphasises the role of WW-based epidemiology.     

Modelling of a novel x-ray phase contrast imaging technique based on coded apertures

X-ray phase contrast imaging is probably the most relevant among emerging x-ray imaging techniques, and it has the proven potential of revolutionizing the field of diagnostic radiology. Impressive images of a wide range of samples have been obtained, mostly at synchrotron radiation facilities. The necessity of relying on synchrotron radiation has prevented to a large extent a widespread diffusion of phase contrast imaging, thus precluding its transfer to clinical practice. A new technique, based on the use of coded apertures, was recently developed at UCL. This technique was demonstrated to provide intense phase contrast signals with conventional x-ray sources and detectors. Unlike other attempts at making phase contrast imaging feasible with conventional sources, the coded-aperture approach does not impose substantial limitations and/or filtering of the radiation beam, and it therefore allows, for the first time, exposures compatible with clinical practice. The technique has been thoroughly modelled, and this paper describes the technique in detail by going through the different steps of the modelling. All the main factors influencing image quality are discussed, alongside the viability of realizing a prototype suitable for clinical use. The model has been experimentally validated and a section of the paper shows the comparison between simulated and experimental results.     

The Sequential Relation Between Changes in Catastrophizing and Changes in Posttraumatic Stress Disorder Symptom Severity

Catastrophizing has been discussed as a cognitive precursor to the emergence of posttraumatic stress disorder (PTSD) symptoms following the experience of stressful events. Implicit in cognitive models of PTSD is that treatment-related reductions in catastrophizing should yield reductions in PTSD symptoms. The tenability of this prediction has yet to be tested. The present study investigated the sequential relation between changes in a specific form of catastrophizing—symptom catastrophizing—and changes in PTSD symptom severity in a sample of 73 work-disabled individuals enrolled in a 10-week behavioral activation intervention. Measures of symptom catastrophizing and PTSD symptom severity were completed at pre-, mid-, and posttreatment assessment points. Cross-sectional analyses of pretreatment data revealed that symptom catastrophizing accounted for significant variance in PTSD symptom severity, β = .40, p < .001, sr = .28 (medium effect size), even when controlling for known correlates of symptom catastrophizing, such as pain and depression. Significant reductions in symptom catastrophizing and PTSD symptoms were observed during treatment, with large effect sizes, ds = 1.42 and 0.94, respectively, ps < .001. Cross-lagged analyses revealed that early change in symptom catastrophizing predicted later change in PTSD symptoms; early changes in PTSD symptom severity did not predict later change in symptom catastrophizing. These findings are consistent with the conceptual models that posit a causal relation between catastrophizing and PTSD symptom severity. The clinical implications of the findings are discussed.