ABSTRACT
IntroductionIn the current SARS-CoV-2 pandemic, testing for SARS-CoV-2 specific antibodies is paramount to monitor immune responses in post-authorization vaccination and sero-epidemiology studies. However, large scale and iterative serological testing by venipuncture in older persons can be challenging. Capillary blood sampled using a finger prick and collected on protein saver cards, i.e., dried blood spots (DBS), has already proven to be a promising alternative. However, elderly persons have a reduced cutaneous microvasculature, which may affect DBS-based antibody testing. Therefore, we aimed to evaluate the performance of DBS for the detection of SARS-CoV-2 antibodies in nursing homes residents. Materials and methodsWe collected venous blood and paired Whatman and EUROIMMUN DBS from nursing home residents, and from staff as a reference population. Venous blood samples were analyzed for the presence of SARS-CoV-2 IgG antibodies using the Abbot chemiluminescent microparticle immunoassay (CMIA). DBS were analyzed by the EUROIMMUN enzyme-linked immuno sorbent assay (ELISA) for SARS-CoV-2 IgG antibodies. We performed a statistical assessment to optimize the ELISA cut-off value for the DBS using the Youdens J index. ResultsA total of 273 paired DBS-serum samples were analyzed, of which 129 were positive as assessed by the reference test. The sensitivities and specificities of DBS ranged from 95.0% to 97.1% and from 97.1% to 98.8%, respectively, depending on population (residents or staff) or DBS card type. ConclusionDBS sampling is a valid alternative to venipuncture for the detection of SARS-CoV-2 antibodies in the elderly.
ABSTRACT
Sustaining a traumatic brain injury (TBI) during adolescence has a profound effect on brain development and can result in persistent executive functioning deficits in daily life. Cognitive recovery from pediatric-TBI relies on the potential of neuroplasticity, which can be fostered by restorative training-programs. However the structural mechanisms underlying cognitive recovery in the immature brain are poorly understood. This study investigated gray matter plasticity following 2â¯months of cognitive training in young patients with TBI. Sixteen adolescents in the chronic stage of moderate-severe-TBI (9 male, mean ageâ¯=â¯15y8m⯱â¯1y7m) were enrolled in a cognitive computerized training program for 8â¯weeks (5 times/week, 40â¯min/session). Pre-and post-intervention, and 6â¯months after completion of the training, participants underwent a comprehensive neurocognitive test-battery and anatomical Magnetic Resonance Imaging scans. We selected 9 cortical-subcortical Regions-Of-Interest associated with Executive Functioning (EF-ROIs) and 3 control regions from the Desikan-Killiany atlas. Baseline analyses showed significant decreased gray matter density in the superior frontal gyri pâ¯=â¯0.033, superior parietal gyri pâ¯=â¯0.015 and thalamus pâ¯=â¯0.006 in adolescents with TBI compared to age and gender matched controls. Linear mixed model analyses of longitudinal volumetric data of the EF-ROI revealed no strong evidence of training-related changes in the group with TBI. However, compared to the change over time in the control regions between post-intervention and 6â¯months follow-up, the change in the EF-ROIs showed a significant difference. Exploratory analyses revealed a negative correlation between the change on the Digit Symbol Substitution test and the change in volume of the putamen (râ¯=â¯-0.596, pâ¯=â¯0.015). This preliminary study contributes to the insights of training-related plasticity mechanisms after pediatric-TBI.