Zimatore, G. | bioRxiv Science

bioRxiv2021

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.

biophysics↗

bioRxiv2019

Self-Organization of Whole Gene Expression through Coordinated Chromatin Structural Transition: Validation of Self-Organized Critical Control of Genome Expression

Through our studies on whole genome regulation, we have demonstrated the existence of self-organized critical control (SOC) of whole gene expression - genomic self-organization mechanism through the emergence of a critical point (CP) at both the cell population and single cell level. In this paper, based on HRG and EGF-stimulated MCF-7 breast-cancer cell line, we shed light on the origin of critical transitions stemming from coordinated chromatin remodeling. In so doing, we validated the core of the SOC control mechanism through the application of a non-linear signal analysis technique (Recurrence Quantification Analysis: RQA), and of Principal Component Analysis (PCA). The main findings were: O_LITranscriptional co-regulation follows a strong and invariant exponential decay as between gene spacing along the chromosome is increased. This shows that the co-regulation occurs on a mainly positional basis reflecting local chromatin organization. C_LIO_LIThere are two main fluctuation modes on the top of the cell-kind specific gene expression values spanning the entire genome expression. These modes establish an autonomous genomic critical control system (genome-engine) through the activation of the CP for cell-fate guiding critical transitions revealed by SOC analysis. C_LI The elucidation of the link between spatial position on chromosome and co-regulation together with the identification of specific locations on the genome devoted to the generalization of perturbation stimuli, give a molecular basis to the self-organization dynamics of genome expression and cell-fate decision.

genomics↗