Recurrence quantification analysis of heart rate variability is a COVID-safe alternative to gas analysis in the detection of metabolic thresholds

The first aim of the study was to verify if in individuals with different physical fitness levels the Recurrence Quantification Analysis (RQA) of Heart Rate Variability (HRV) time series could be an alternative to Gas Exchange (GE) analysis in the determination of metabolic thresholds. The second aim was to investigate the validity of the RQA method compared to the GE method in thresholds detection. The two metabolic thresholds were estimated in thirty young individuals during Cardiopulmonary Exercise Testing on a cycle-ergometer and HR, VO2 and Workload were measured by the two different methods (RQA and GE methods). RM ANOVA was used to assess main effects of methods and methods-by-groups interaction effects for HR, VO2 and Workload at the aerobic (AerT) and the anaerobic (AnT) thresholds. Validity of the RQA at both thresholds was assessed for HR, VO2 and Workload by Ordinary Least Products (OLP) regression analysis, Typical Percentage Errors (TE), Intraclass Correlation Coefficients (ICC) and the Bland Altman plots. No methods-by-groups interaction effects were detected for HR, VO2 and Workload at the AerT and the AnT. The OLP regression analysis showed that at both thresholds RQA and GE methods had very strong correlations (r >0.8) in all variables (HR, VO2 and Workload). Slope and intercept values always included the 1 and the 0, respectively. At the AerT the TE ranged from 4.02% to 10.47% (HR and Workload, respectively) and in all variables ICC values were excellent ([≥]0.85). At the AnT the TE ranged from 2.61% to 6.64% (HR and Workload, respectively) and in all variables ICC values were excellent ([≥]0.89). Our results suggest that the RQA of HRV time series is a COVID-safe approach for the determination of metabolic thresholds in individuals with different physical fitness levels, therefore, it can be used as a valid method for threshold detection alternative to gas analysis.

Graphene nanoplatelet and Graphene oxide functionalization of face mask materials inhibits infectivity of trapped SARS-CoV-2

Recent advancements in bidimensional nanoparticles such as Graphene nanoplatelets (G) and the derivative Graphene oxide (GO) have the potential to meet the need for highly functional personal protective equipment (PPE) that confers increased protection against SARS-CoV-2 infection and the spread COVID-19. The ability of G and GO to interact with and bind microorganisms as well as RNA and DNA provides an opportunity to develop engineered textiles for use in PPE. The face masks widely used in health care and other high-risk settings for COVID transmission provide only a physical barrier that decreases likelihood of infection and do not inactivate the virus. Here, we show pre-incubation of viral particles with free GO inhibits SARS-CoV-2 infection of VERO cells. Highly relevant to PPE materials, when either polyurethane or cotton material was loaded with G or GO and culture medium containing SARS-CoV-2 viral particles either filtered through or incubated with the functionalized materials, the infectivity of the medium was nearly completely inhibited. The findings presented here constitute an important nanomaterials-based strategy to significantly increase face mask and other PPE efficacy in protection against the SARS-CoV-2 virus and COVID-19 that may be applicable to additional anti-SARS-CoV-2 measures including water filtration, air purification, and diagnostics. One Sentence SummaryCotton and polyurethane materials functionalized with bidimensional Graphene nanoplatelets trap SARS-CoV-2 and have the potential to reduce spread of COVID-19.

Extracellular truncated tau causes early presynaptic dysfunction associated with Alzheimer's disease and other tauopathies.

The largest part of tau secreted from AD nerve terminals and released in cerebral spinal fluid (CSF) is C-terminally truncated, soluble and unaggregated supporting potential extracellular role(s) of NH2 -derived fragments of protein on synaptic dysfunction underlying neurodegenerative tauopathies, including Alzheimer's disease (AD). Here we show that sub-toxic doses of extracellular-applied human NH2 tau 26-44 (aka NH 2 htau) -which is the minimal active moiety of neurotoxic 20-22kDa peptide accumulating in vivo at AD synapses and secreted into parenchyma- acutely provokes presynaptic deficit in K+ -evoked glutamate release on hippocampal synaptosomes along with alteration in local Ca2+ dynamics. Neuritic dystrophy, microtubules breakdown, deregulation in presynaptic proteins and loss of mitochondria located at nerve endings are detected in hippocampal cultures only after prolonged exposure to NH 2 htau. The specificity of these biological effects is supported by the lack of any significant change, either on neuronal activity or on cellular integrity, shown by administration of its reverse sequence counterpart which behaves as an inactive control, likely due to a poor conformational flexibility which makes it unable to dynamically perturb biomembrane-like environments. Our results demonstrate that one of the AD-relevant, soluble and secreted N-terminally truncated tau forms can early contribute to pathology outside of neurons causing alterations in synaptic activity at presynaptic level, independently of overt neurodegeneration.