Two Operational Modes of Cardio-Respiratory Coupling Revealed by Pulse-Respiration Quotient.

Due to the fact that respiratory breath-to-breath and cardiac intervals between two successive R peaks ( and , respectively) are not temporally concurrent, in a previous paper, we proposed a method to calculate both the integer and non-integer parts of the pulse respiration quotient ( = / = + + ), and being parts of the border for each . In this work, we study the correlations between and , as well as those between and mean within each (), on a group of twenty subjects in four conditions: in supine and standing positions, in combination with spontaneous and slow breathing. Results show that the vs.

Pulse respiration quotient as a measure sensitive to changes in dynamic behavior of cardiorespiratory coupling such as body posture and breathing regime.

In this research we explored the (homeo)dynamic character of cardiorespiratory coupling (CRC) under the influence of different body posture and breathing regimes. Our tool for it was the pulse respiration quotient (PRQ), representing the number of heartbeat intervals per breathing cycle. We obtained non-integer PRQ values using our advanced Matlab algorithm and applied it on the signals of 20 healthy subjects in four conditions: supine position with spontaneous breathing (Supin), standing with spontaneous breathing (Stand), supine position with slow (0.

In Silico Screening of Natural Compounds for Candidates 5HT6 Receptor Antagonists against Alzheimer's Disease.

Alzheimer's disease (AD), a devastating neurodegenerative disease, is the focus of pharmacological research. One of the targets that attract the most attention for the potential therapy of AD is the serotonin 5HT6 receptor, which is the receptor situated exclusively in CNS on glutamatergic and GABAergic neurons. The neurochemical impact of this receptor supports the hypothesis about its role in cognitive, learning, and memory systems, which are of critical importance for AD.

Slow 0.1 Hz Breathing and Body Posture Induced Perturbations of RRI and Respiratory Signal Complexity and Cardiorespiratory Coupling.

We explored the physiological background of the non-linear operating mode of cardiorespiratory oscillators as the fundamental question of cardiorespiratory homeodynamics and as a prerequisite for the understanding of neurocardiovascular diseases. We investigated 20 healthy human subjects for changes using electrocardiac RR interval (RRI) and respiratory signal (Resp) Detrended Fluctuation Analysis (DFA, α, α, α, α), Multiple Scaling Entropy (MSE, MSE, MSE, MSE), spectral coherence (Coh), cross DFA (ρ and ρ) and cross MSE (X and X) indices in four physiological conditions: supine with spontaneous breathing, standing with spontaneous breathing, supine with 0.1 Hz breathing and standing with 0.

Generalized Poincaré plots analysis of heart period dynamics in different physiological conditions: Trained vs. untrained men.

Background: Recently we proposed a new method called generalized Poincaré plot (gPp) analysis which gave a new insight into the pattern of neurocaridac control. In this study we examined potential of gPp method to reveal changes in cardiac neural control in young athletes during three conditions: supine rest, running and relaxation, with respect to untrained subjects.

Methods: This method is based on the quantification of Pearson's correlation coefficients r(j, k), between symmetrical (j = k) and asymmetrical summed j previous and k following RR intervals up to the 100th order (j,k≤100).

Identification of Candidate Allosteric Modulators of the M1 Muscarinic Acetylcholine Receptor Which May Improve Vagus Nerve Stimulation in Chronic Tinnitus.

Chronic tinnitus is characterized by neuroplastic changes of the auditory cortex. A promising method for therapy of chronic tinnitus is vagus nerve stimulation (VNS) combined with auditory stimulation. The principle of VNS is reversal of pathological neuroplastic changes of the auditory cortex toward physiological neural activity and synchronicity.

New complexity measures reveal that topographic loops of human alpha phase potentials are more complex in drowsy than in wake.

A number of measures, stemming from nonlinear dynamics, exist to estimate complexity of biomedical objects. In most cases they are appropriate, but sometimes unconventional measures, more suited for specific objects, are needed to perform the task. In our present work, we propose three new complexity measures to quantify complexity of topographic closed loops of alpha carrier frequency phase potentials (CFPP) of healthy humans in wake and drowsy states.

Uncoupling of cardiac and respiratory rhythm in atrial fibrillation.

Rearranged origin of heart rhythm in patients with atrial fibrillation (AF) influences the regulation of the heart and consequently the respiratory rhythm, and the bidirectional interaction of these rhythms not documented. Hence, we examined coupling of the RR interval and the respiration (Resp) signal by coherence, Granger causality and the cross-sample entropy method of time series analysis in patients with AF and a healthy control group. In healthy subjects, the influence of respiration on cardiac rhythm was found as increased coherence at the breathing frequency (BF) range, significantly stronger interaction and synchrony from Resp to RR than from RR to Resp.

Common molecular mechanism of the hepatic lesion and the cardiac parasympathetic regulation in chronic hepatitis C infection: a critical role for the muscarinic receptor type 3.

Background: The pathophysiological overlapping between Sjorgen's Syndrome (SS) and HCV, presence of anti- muscarinic receptor type 3 (M3R) antibodies in SS, the role that M3R plays in the regulation of the heart rate, has led to the assumption that cardiovagal dysfunction in HCV patients is caused by anti-M3R antibodies elicited by HCV proteins or by their direct interaction with M3R.

Results: To identify HCV protein which possibly is crossreactive with M3R or which binds to this receptor, we performed the Informational Spectrum Method (ISM) analysis of the HCV proteome. This analysis revealed that NS5A protein represents the most probable interactor of M3R or that this viral protein could elicit antibodies which modulate function of this receptor.

Generalized Poincaré Plots-A New Method for Evaluation of Regimes in Cardiac Neural Control in Atrial Fibrillation and Healthy Subjects.

Classical Poincaré plot is a standard way to measure nonlinear regulation of cardiovascular control. In our work we propose a generalized form of Poincaré plot where we track correlation between the duration of j preceding and k next RR intervals. The investigation was done in healthy subjects and patients with atrial fibrillation, by varying j,k ≤ 100.

In silico Therapeutics for Neurogenic Hypertension and Vasovagal Syncope.

Neurocardiovascular diseases (NCVD) are the leading cause of death in the developed world and will remain so till 2020. In these diseases the pathologically changed nervous control of cardiovascular system has the central role. The actual NCV syndromes are neurogenic hypertension, representing the sympathetically mediated disorder, and vasovagal syncope, which is the vagally mediated disorders.

Topographic distribution of EEG alpha attractor correlation dimension values in wake and drowsy states in humans.

Organization of resting state cortical networks is of fundamental importance for the phenomenon of awareness, which is altered in the first part of hypnagogic period (Hori stages 1-4). Our aim was to investigate the change in brain topography pattern of EEG alpha attractor correlation dimension (CD) in the period of transition from Hori stage 1 to 4. EEG of ten healthy adult individuals was recorded in the wake and drowsy states, using a 14 channel average reference montage, from which 91 bipolar channels were derived and filtered in the wider alpha (6-14 Hz) range.

Nonlinear properties of cardiac rhythm and respiratory signal under paced breathing in young and middle-aged healthy subjects.

We examined the effects of gender and age in young and middle-aged subjects on the level of cardio-respiratory interaction by analyzing properties of cardiac, respiratory and cardiac-respiratory regulatory mechanisms under paced breathing. In 56 healthy subjects, ECG (RR interval) and respiratory signal were simultaneously acquired in supine position at paced (0.1-0.

RR interval-respiratory signal waveform modeling in human slow paced and spontaneous breathing.

Our aim was to model the dependence of respiratory sinus arrhythmia (RSA) on the respiratory waveform and to elucidate underlying mechanisms of cardiorespiratory coupling. In 30 subjects, RR interval and respiratory signal were recorded during spontaneous and paced (0.1Hz/0.

Influenza vaccine as prevention for cardiovascular diseases: possible molecular mechanism.

Despite plausible evidence for beneficial effects of the vaccination against influenza in cardiovascular diseases (CVD) very limited studies have been carried out to explain the molecular mechanism of this phenomenon. Using the informational spectrum method (ISM), a virtual spectroscopy method for analysis of protein-protein interactions, the bradykinin 2 receptor (BKB2R) was identified as a principal host protein which could mediate molecular processes underlying the cardioprotective effect of influenza vaccines. Based on this finding we suggest that some antibodies elicited by influenza vaccines act as agonists, which activate a BKB2R-associated signaling pathway contributing to the protection against CVD.

The role of G protein coupled receptor kinases in neurocardiovascular pathophysiology.

In coronary artery disease the G protein related kinases (GRKs) play a role in desensitization of β-adrenoreceptors (AR) after coronary occlusion. Targeted deletion and lowering of cardiac myocyte GRK-2 decreases the risk of post-ischemic heart failure (HF). Studies carried out in humans confirm the role of GRK-2 as a marker for the progression of HF after myocardial infarction (MI).

Modeling the relationship between Higuchi's fractal dimension and Fourier spectra of physiological signals.

The exact mathematical relationship between FFT spectrum and fractal dimension (FD) of an experimentally recorded signal is not known. In this work, we tried to calculate signal FD directly from its Fourier amplitudes. First, dependence of Higuchi's FD of mathematical sinusoids on their individual frequencies was modeled with a two-parameter exponential function.

EEG alpha phase shifts during transition from wakefulness to drowsiness.

Phases of alpha oscillations recorded by EEG were typically studied in the context of event or task related experiments, rarely during spontaneous alpha activity and in different brain states. During wake-to-drowsy transition they change unevenly, depending on the brain region. To explore their dynamics, we recorded ten adult healthy individuals in these two states.

Temporal analysis of the spontaneous baroreceptor reflex during mild emotional stress in the rat.

The effect of emotional stress on the spontaneous baroreceptor reflex (sBRR) in freely moving rats was investigated. Six male Wistar rats equipped with an intra-arterial polyethylene catheter were exposed to a 2-min air-jet stress. For time course analysis of the sBRR response to stress, the records of systolic blood pressure (SBP) and pulse interval (PI) were divided into five regions: baseline (BASELINE), acute exposure to air-jet stress (STRESS), immediate recovery (IMMED.

Heart rate variability in children with exercise-induced idiopathic ventricular arrhythmias.

Ventricular arrhythmias (VAs) are common pediatric rhythm disorders requiring comprehensive laboratory evaluation. Although usually idiopathic, implying a benign character and favorable prognosis, the initial clinical approach is still not established in all cases. Considering their prognostic significance, exercise-induced (precipitated or aggravated) VAs usually require additional diagnostics, treatment, and follow-up.

Modeling EEG fractal dimension changes in wake and drowsy states in humans--a preliminary study.

Aim of this preliminary study was to examine and compare topographic distribution of Higuchi's fractal dimension (FD, measure of signal complexity) of EEG signals between states of relaxed wakefulness and drowsiness, as well as their FD differences. The experiments were performed on 10 healthy individuals using a fourteen-channel montage. An explanation is offered on the causes of the detected FD changes.