The sensitivity of SARS-CoV-2 antigen tests in the view of large-scale testing.

OBJECTIVES: Antigen tests have emerged as an alternative to SARS-CoV-2 diagnostic PCR, thought to be valuable especially for the screening of bigger communities. To check appropriateness of the antigen based testing, we determined sensitivity of two point-of-care antigen tests when applied to a cohort of COVID-19 symptomatic, COVID-19 asymptomatic and healthy persons. METHODS: We examined nasopharyngeal swabs with antigen test 1 (Panbio Covid-19 Ag Rapid Test, Abbott) and antigen test 2 (Standard F Covid-19 Ag FIA, SD Biosensor). An additional nasopharyngeal and oropharyngeal swab of the same individual was checked with PCR (Allplex SARS-nCoV-2, Seegene). Within a 4-day period in October 2020, we collected specimens from 591 subjects. Of them, 290 had COVID-19 associated symptoms. RESULTS: While PCR positivity was detected in 223 cases, antigen test 1 and antigen test 2 were found positive in 148 (sensitivity 0.664, 95%CI 0.599, 0.722) and 141 (sensitivity 0.623, 95%CI 0.558, 0.684) patients, respectively. When only symptomatic patients were analysed, sensitivity increased to 0.738 (95%CI 0.667, 0.799) for the antigen test 1 and to 0.685 (95%CI 0.611, 0.750) for the antigen test 2. The substantial drop in sensitivity to 12.9% (95%CI 0.067, 0.234) was observed for samples with the PCR threshold cycle above > 30. CONCLUSIONS: Low sensitivity of antigen tests leads to the considerable risk of false negativity. It is advisable to implement repeated testing with high enough frequency if the antigen test is used as a frontline screening tool, and to follow with PCR if it is applied to vulnerable populations.

Age-Related Differences in Socio-demographic and Behavioral Determinants of HIV Testing and Counseling in HPTN 043/NIMH Project Accept.

Youth represent a large proportion of new HIV infections worldwide, yet their utilization of HIV testing and counseling (HTC) remains low. Using the post-intervention, cross-sectional, population-based household survey done in 2011 as part of HPTN 043/NIMH Project Accept, a cluster-randomized trial of community mobilization and mobile HTC in South Africa (Soweto and KwaZulu Natal), Zimbabwe, Tanzania and Thailand, we evaluated age-related differences among socio-demographic and behavioral determinants of HTC in study participants by study arm, site, and gender. A multivariate logistic regression model was developed using complete individual data from 13,755 participants with recent HIV testing (prior 12 months) as the outcome. Youth (18-24 years) was not predictive of recent HTC, except for high-risk youth with multiple concurrent partners, who were less likely (aOR 0.75; 95% CI 0.61-0.92) to have recently been tested than youth reporting a single partner. Importantly, the intervention was successful in reaching men with site specific success ranging from aOR 1.27 (95% CI 1.05-1.53) in South Africa to aOR 2.30 in Thailand (95% CI 1.85-2.84). Finally, across a diverse range of settings, higher education (aOR 1.67; 95% CI 1.42, 1.96), higher socio-economic status (aOR 1.21; 95% CI 1.08-1.36), and marriage (aOR 1.55; 95% CI 1.37-1.75) were all predictive of recent HTC, which did not significantly vary across study arm, site, gender or age category (18-24 vs. 25-32 years).

Incidence of non-lung solid cancers in Czech uranium miners: a case-cohort study.

OBJECTIVES: Uranium miners are chronically exposed to radon and its progeny, which are known to cause lung cancer and may be associated with leukemia. This study was undertaken to evaluate risk of non-lung solid cancers among uranium miners in Príbram region, Czech Republic. METHODS: A retrospective stratified case-cohort study in a cohort of 22,816 underground miners who were employed between 1949 and 1975. All incident non-lung solid cancers were ascertained among miners who worked underground for at least 12 months (n=1020). A subcohort of 1707 subjects was randomly drawn from the same population by random sampling stratified on age. The follow-up period lasted from 1977 to 1996. RESULTS: Relative risks comparing 180 WLM (90th percentile) of cumulative lifetime radon exposure to 3 WLM (10th percentile) were 0.88 for all non-lung solid cancers combined (95% CI 0.73-1.04, n=1020), 0.87 for all digestive cancers (95% CI 0.69-1.09, n=561), 2.39 for gallbladder cancer (95% CI 0.52-10.98, n=13), 0.79 for larynx cancer (95% CI 0.38-1.64, n=62), 2.92 for malignant melanoma (95% CI 0.91-9.42, n=23), 0.84 for bladder cancer (95% CI 0.43-1.65, n=73), and 1.13 for kidney cancer (95% CI 0.62-2.04, n=66). No cancer type was significantly associated with radon exposure; only malignant melanoma and gallbladder cancer showed elevated but non-significant association with radon. CONCLUSIONS: Radon was not significantly associated with incidence of any cancer of interest, although a positive association of radon with malignant melanoma and gallbladder cancer cannot be entirely ruled out.

Effect of diabetes mellitus type 1 diagnosis on the corneal cell densities and nerve fibers.

Relation of diabetes mellitus (DM) to the various stages of corneal nerve fiber damage is well accepted. A possible association between changes in the cornea of diabetic patients and diabetic retinopathy (DR), DM duration, and age at the time of DM diagnosis were evaluated. The study included 60 patients with DM type 1 (DM1) and 20 healthy control subjects. The density of basal epithelial cells, keratocytes and endothelial cells, and the status of the subbasal nerve fibers were evaluated using in vivo corneal confocal microscopy. Basal epithelial cell density increased with age (p=0.026), while stromal and endothelial cell density decreased with age (p=0.003, p=0.0005, p<0.0001). After the DM1 diagnosis was established, this association with age weaken. We showed nerve fiber damage in DM1 patients (p<0.0001). The damage correlated with the degree of DR. DM1 patients with higher age at DM1 diagnosis had a higher nerve fiber density (p=0.0021). These results indicated that age at DM1 diagnosis potentially has an important effect on final nerve fiber and corneal cell density.

Ultra-lightweight superconducting wire based on Mg, B, Ti and Al.

Actually, MgB2 is the lightest superconducting compound. Its connection with lightweight metals like Ti (as barrier) and Al (as outer sheath) would result in a superconducting wire with the minimal mass. However, pure Al is mechanically soft metal to be used in drawn or rolled composite wires, especially if applied for the outer sheath, where it cannot provide the required densification of the boron powder inside. This study reports on a lightweight MgB2 wire sheathed with aluminum stabilized by nano-sized γ-Al2O3 particles (named HITEMAL) and protected against the reaction with magnesium by Ti diffusion barrier. Electrical and mechanical properties of single-core MgB2/Ti/HITEMAL wire made by internal magnesium diffusion (IMD) into boron were studied at low temperatures. It was found that the ultra-lightweight MgB2 wire exhibited high critical current densities and also tolerances to mechanical stress. This predetermines the potential use of such lightweight superconducting wires for aviation and space applications, and for powerful offshore wind generators, where reducing the mass of the system is required.

Low mortality of children undergoing hematopoietic stem cell transplantation from 7 to 8/10 human leukocyte antigen allele-matched unrelated donors with the use of antithymocyte globulin.

Human leukocyte antigen (HLA)-matched sibling donor hematopoietic stem cell transplantation (HSCT) is available for only approximately 30% patients needing HSCT. Use of alternative donors is associated with a high incidence and severity of graft-versus-host disease (GVHD). Here we report our experience with GVHD prophylaxis using pre-transplant rabbit antithymocyte globulin (rATG), in addition to post transplant cyclosporin A and methotrexate. Seventy-five children received unmanipulated grafts from 7 to 10/10 HLA allele-matched unrelated donors. Median follow-up was 25 months (range, 6-65 months). Only 2/75 patients (2.5%) developed acute GVHD grades III-IV, and 17/75 (25%) developed extensive chronic GVHD. Overall survival was 79%. It was similar in patients receiving grafts from 7 or 8/10 to 9 or 10/10 allele-matched donors, and similar in patients receiving peripheral blood stem cells and marrow. Six (11%) patients died owing to relapse, and 10 (13%) due to transplant-related complications. The addition of rATG appears to result in a low incidence of severe GVHD and overall mortality.

[EBV quantification in children after allogeneic hematopoietic stem cell transplantation]. / Kvantifikace EBV u detí po alogenní transplantaci hematopoetických kmenových bunek.

BACKGROUND: Patients undergoing allogeneic hematopoietic stem cell transplantation (AHSCT) are endangered by developing Epstein-Barr virus-related post-transplant lymfoprolipherative disease (EBV-LPD). The aims of the study were to retrospectively characterise the viral loads in four patients who died of this complication, and to test possible risk factors for EBV reactivation in a prospectively observed cohort of children after AHSCT. METHODS AND RESULTS: Serial DNA samples extracted from whole blood from four patients who died of post-transplant EBV-LPD in year 2000 were retrospectively analysed for EBV load using quantitative real-time PCR. First detection of EBV activation preceded death by 24-91 days. All four patients exceeded a viral load of one million EBV copies per 100,000 human genome equivalents. A cohort of 72 children undergoing AHSCT between 2001-2004 was prospectively followed-on using the same quantification method from regularly obtained samples of whole blood, and clinical and laboratory data were recorded on a weekly basis, totalling at 3,896 person-weeks of observation. Approximately one half of the cohort experienced at least one episode of EBV reactivation during the first 100 days after AHSCT, four of the episodes being accompanied with viral loads higher than our provisional threshold of 10,000 copies per 100,000 human genome equivalents. Three of the four patients developed EBV-LPD and were successfully treated by intravenous administration of anti-CD20 antibody. Testing of possible clinical and laboratory predictors of EBV reactivation did not reveal any clinically useful association. CONCLUSIONS: The cornerstone of predicting EBV-LPD in AHSCT is a regular monitoring of EBV viral load using quantitative methods. Using this strategy with a threshold of 10,000 EBV copies per 100,000 human genome equivalents was proved to be effective, as shown by no death of EBV for the study period, compared to four cases in the year before the quantitative monitoring.