Spontaneous Variability Research Articles

Evaluation of the impact of surgical aortic valve replacement on short-term cardiovascular and cerebrovascular controls through spontaneous variability analysis.

We assessed the effect of surgical aortic valve replacement (SAVR) on cardiovascular and cerebrovascular controls via spontaneous variability analyses of heart period, approximated as the temporal distance between two consecutive R-wave peaks on the electrocardiogram (RR), systolic, diastolic and mean arterial pressure (SAP, DAP and MAP) and mean cerebral blood flow (MCBF). Powers in specific frequency bands, complexity, presence of nonlinear dynamics and markers of cardiac baroreflex and cerebral autoregulation were calculated. Variability series were acquired before (PRE) and after (POST) SAVR in 11 patients (age: 76±5 yrs, 7 males) at supine resting and during active standing. Parametric spectral analysis was performed based on the autoregressive model. Complexity was assessed via a local nonlinear prediction approach exploiting the k-nearest-neighbor strategy. The presence of nonlinear dynamics was checked by comparing the complexity marker computed over the original series with the distribution of the same index assessed over a set of surrogates preserving distribution and power spectral density of the original series. Cardiac baroreflex and cerebral autoregulation were estimated by assessing the transfer function from SAP to RR and from MAP to MCBF and squared coherence function via the bivariate autoregressive approach. We found that: i) orthostatic challenge had no effect on cardiovascular and cerebrovascular control markers in PRE; ii) RR variance was significantly reduced in POST; iii) complexity of SAP, DAP and MAP variabilities increased in POST with a greater likelihood of observing nonlinear dynamics over SAP compared to PRE at supine resting; iv) the amplitude of MCBF variations and MCBF complexity in POST remained similar to PRE; v) cardiac baroreflex sensitivity decreased in POST, while cerebrovascular autoregulation was preserved. SAVR induces important changes of cardiac and vascular autonomic controls and baroreflex regulation in patients exhibiting poor reactivity of cardiovascular regulatory mechanisms, while cerebrovascular autoregulation seems to be less affected.

Influence of seasonal changes on the karyotype stability of Ukrainian Black and White dairy cows

Of the total dairy cattle, 49 % belong to the Ukrainian black-and-white dairy breed. Animals are demanding to the conditions of detention, so the aim of the study was to study the impact of seasonal changes in the environment on the stability of the karyotype of cows of three age groups (first-born, adult and cows 8–10 years). The variability of the karyotype of the studied animals in different seasons of the year was manifested in the form of quantitative and structural disorders of chromosomes. Of the total dairy cattle, 49 % belong to the Ukrainian black-and-white dairy breed. Animals are demanding to the conditions of detention, so the aim of the study was to study the impact of seasonal changes in the environment on the stability of the karyotype of cows of three age groups (first-born, adult and cows 8–10 years). The variability of the karyotype of the studied animals in different seasons of the year was manifested in the form of quantitative and structural disorders of chromosomes. In primiparous women, the most pronounced genomic variability (aneuploidy) was observed in summer and winter and was 16.4 % and 8.8 %. In summer, this variability was more than twice the limit of spontaneous chromosomal variability. The highest percentage of structural chromosome abnormalities (chromosomal breaks) in cows of three age groups was observed in winter and was 2.5 %, 2.8 %, 3.0 %, respectively, and did not exceed the limit of spontaneous mutagenesis characteristic of cattle. An increased proportion of lymphocytes with a micronucleus in first-borns and cows aged 8–10 years (5.6 ‰, 6.4 ‰, respectively) was observed in the summer. The increased proportion of dinuclear lymphocytes appeared in the first-born in the summer season and amounted to 7.6 ‰ (at P > 0.99), and in cows 8–10 years, this variability in the summer season was 6.2 ‰, in winter – 6.7 ‰ with a statistically significant difference (P > 0.95) between the spontaneous level of cytogenetic variability. The association between karyotype stability of the studied animals and seasonal environmental factors was determined using a correlation coefficient (r). A significant positive correlation was found between aneuploidy and air temperature in primiparous and cows aged 8–10 years, relative humidity, precipitation and wind strength and chromosomal gaps in primiparous and adult cows, atmospheric pressure, relative humidity and asynchronous divergence. in adult cows and cows aged 8–10 years. A positive reliable associative dependence of the appearance of micronucleus lymphocytes and dinuclear lymphocytes on the amount of precipitation and wind strength in this area in primiparous and adult cows was established.

Ajmaline Testing and the Brugada Syndrome

Brugada syndrome (BrS) diagnosis requires the presence of a typical type 1 ECG pattern. Owing to the spontaneous ECG variability, the real BrS prevalence in the general population remains unclear. The aim of the present study was to evaluate the prevalence of positive ajmaline challenge for BrS in a cohort of consecutive patients who underwent electrophysiological evaluation for different clinical reasons. All consecutive patients from 2008 to 2019 who underwent ajmaline testing were prospectively included. A total of 2,456 patients underwent ajmaline testing, 742 (30.2%) in the context of familial screening for BrS. In non-familial screening group (1,714) ajmaline testing resulted positive in 186 (10.9%). Indications for ajmaline testing were: suspicious BrS ECG in 23 cases (12.4%), palpitations in 27 (14.5%), syncope in 71 (38.2%), presyncope in 7 (3.8%), family history of sudden cardiac death in 18 (9.7%), documented ventricular arrhythmias in 12 (6.5%), unexplained cardiac arrest in 4 (2.2%), atrial fibrillation in 16 (8.5%), brady-arrhythmias in 1 (0.5%), and cerebrovascular accidents in 7 (3.7%). Compared with the overall population, ajmaline testing positive patients were younger (42.8 ± 15.5 vs 48.9 ± 20.4; p <0.001) and more frequently male (65.1% vs 56.3%; p = 0.023). Implantable cardioverter defibrillator was implanted in 84 patients (45.2%). During a median follow-up of 42.4 months, 12 appropriate shocks and 13 implantable cardioverter defibrillator related complications were reported. In conclusion, the BrS was diagnosed in an unexpected high proportion of patients that underwent ajmaline testing for a variety of cardiovascular symptoms. This can lead to an adequate counseling and clinical management in BrS patients.

Comparison of symbolization strategies for complexity assessment of spontaneous variability in individuals with signs of cardiovascular control impairment

Symbolic analysis was frequently utilized in cardiovascular control assessment from spontaneous variability of heart period (HP) and systolic arterial pressure (SAP). However, due to different symbolization approaches comparison among studies present in literature is difficult especially on pathological groups with signs of autonomic dysfunction. We performed HP and SAP symbolic analyses via different symbolization methods over a group of Parkinson’s disease (PD) patients with no sign of orthostatic hypotension and over age- and gender-matched healthy (H) controls at rest in supine position (REST) and during head-up tilt (HUT). The most frequently exploited symbolization methods applied directly to the original values, referred to as amplitude-based (AB) techniques, and to their first variations, labeled as variation-based (VB) methods, were compared. The rates of pattern families featuring different amount of variability among symbols were computed. In agreement with the inclusion criteria PD patients could maintain steady SAP during HUT via a tachycardic response. In spite of similar trends symbolic markers exhibited subtle differences. The level of consistency among different symbolic approaches is more dependent on the type of series and pattern family than on symbolization strategy (i.e. AB or VB). Consistency was higher over SAP than HP symbolic indexes and over highly variable patterns than more stable ones. All the symbolic methods detected an increased complexity of cardiac and vascular controls in PD patients compared to H subjects more evident during HUT than at REST. Symbolic markers of highly variable patterns provide interpretation independent of the symbolization technique exploited for their computation.

Complexity and Nonlinearities of Short-Term Cardiovascular and Cerebrovascular Controls after Surgical Aortic Valve Replacement.

We assessed the effect of surgical aortic valve replacement (SAVR) on cardiovascular and cerebrovascular controls with particular attention to their complexity and presence of nonlinear behaviors via the analysis of spontaneous variability of heart period (HP), systolic and diastolic arterial pressure (SAP and DAP) and mean cerebral blood flow (MCBF). Variability series were acquired before (PRE) and after (POST) SAVR in 12 patients (age: 76±4.7 yrs, 7 males) at rest in supine position and during active standing. Complexity was assessed via a local nonlinear prediction approach exploiting the k-nearest neighbor strategy. The presence of nonlinear dynamics was checked by comparing the complexity marker computed over the original series with the distribution of values assessed over 100 surrogates preserving distribution and power spectral density of the original series but with random phases. We found that: i) HP variance was significantly reduced in POST; ii) the complexity of SAP and DAP variabilities increased in POST with a greater likelihood of observing nonlinear dynamics over SAP compared to PRE at supine rest; iii) the amplitude of MCBF fluctuations and its complexity in POST remained similar to PRE. SAVR induces important changes of the cardiac and vascular autonomic controls, while cerebrovascular regulation seems to be less affected.

The effect of personality measurement conditions on spontaneous swimming behavior in the pale chub Zacco platypus (Cyprinidae)

Studies on personality have revealed that some personality traits are strongly correlated; thus, researchers may be able to acquire data for variables related to different personality traits from one measurement. Therefore, the aim of the present study was to test whether spontaneous movement traits used in fish personality measurements are correlated or vary among different contexts in a common Chinese cyprinid fish, the pale chub (Zacco platypus, Cyprinidae). The median swimming speed, percent time spent moving and median turning rate were measured in a boldness context (with a shelter available), then in an exploration context (with a novel object nearby) and finally in a control context (i.e., with no shelter or novel object). The median swimming speed, percent time spent moving, and median turning rate all showed positive correlations between the control and the other two contexts, which suggests that future studies might use spontaneous swimming variables measured in exploration or boldness contexts to avoid the need to carry out a separate activity test. Further analysis comparing the distance to and latency to explore the novel object between the exploration context (with the novel object present) and control context (with an imaginary object at the same position) showed that the amount of time it took for the fish to first reach the object for exploration was significantly shorter in an exploration context than in a control context. This suggests that latency to explore might be useful as a variable indicating exploration in the pale chub in the future.

How fluent? Part B. Underlying contributors to continuous measures of fluency in aphasia

ABSTRACT Background While persons with aphasia (PwA) are often dichotomised as fluent or nonfluent, agreement that fluency is not an all-or-nothing construct has led to the use of continuous variables as a way to quantify fluency, such as multi-dimensional rating scales, speech rate, and utterance length. Though these measures are often used in research, they provide little information about the underlying fluency deficit. Aim The aim of the study was to identify how well commonly used continuous measures of fluency capture variability in spontaneous speech variables at lexical, grammatical, and speech production levels. Methods & Procedures Speech samples of 254 English-speaking PwA from the AphasiaBank database were analyzed to examine the distributions of four continuous measures of fluency: the WAB-R fluency scale, utterance length, retracing, and speech rate. Linear regression was used to identify spontaneous speech predictors contributing to each fluency outcome measure. Outcomes & Results All the outcome measures reflected the influence of multiple underlying dimensions, although the predictors varied. The WAB-R fluency scale, speech rate, and retracing were influenced by measures of grammatical competence, lexical retrieval, and speech production, whereas utterance length was influenced only by measures of grammatical competence and lexical retrieval. The strongest predictor of WAB-R fluency was aphasia severity, whereas the strongest predictor for all other fluency proxy measures was grammatical complexity. Conclusions Continuous measures allow a variety of ways to objectively quantify speech fluency; however, they reflect superficial manifestations of fluency that may be affected by multiple underlying deficits. Furthermore, the deficits underlying different measures vary, which may reduce the reliability of fluency diagnoses. Capturing these differences at the individual level is critical to accurate diagnosis and appropriately targeted therapy.

Fluent or nonfluent? Part A. Underlying contributors to categorical classifications of fluency in aphasia

ABSTRACT Background The concept of fluency is widely used to dichotomously classify aphasia syndromes in both research and clinical practice. Despite its ubiquity, reliability of fluency measurement is reduced due to its multi-dimensional nature and the variety of methods used to measure it. Aims The primary aim of the study was to determine what factors contribute to judgements of fluency in aphasia, identifying methodological and linguistic sources of disagreement. Methods & Procedures We compared fluency classifications generated according to fluency scores on the revised Western Aphasia Battery (WAB-R) to clinical impressions of fluency for 254 English-speaking people with aphasia (PwA) from the AphasiaBank database. To determine what contributed to fluency classifications, we examined syndrome diagnoses and measured the predictive strength of 18 spontaneous speech variables extracted from retellings of the Cinderella story. The variables were selected to represent three dimensions predicted to underlie fluency: grammatical competence, lexical retrieval, and the facility of speech production. Outcomes & Results WAB-R fluency classifications agreed with 83% of clinician classifications, although agreement was much greater for fluent than nonfluent classifications. The majority of mismatches were diagnosed with anomic or conduction aphasia by the WAB-R but Broca’s aphasia by clinicians. Modifying the WAB-R scale improved the extent to which WAB-R fluency categories matched clinical impressions. Fluency classifications were predicted by a combination of variables, including aspects of grammaticality, lexical retrieval and speech production. However, fluency classification by WAB-R was largely predicted by severity, whereas the presence or absence of apraxia of speech was the largest predictor of fluency classifications by clinicians. Conclusions Fluency judgements according to WAB-R scoring and those according to clinical impression showed some common influences, but also some differences that contributed to mismatches in fluency categorization. We propose that, rather than using dichotomous fluency categories, which can mask sources of disagreement, fluency should be explicitly identified relative to the underlying deficits (word-finding, grammatical formulation, speech production, or a combination) contributing to each individual PwA’s fluency profile. Identifying what contributes to fluency disruptions is likely to generate more reliable diagnoses and provide more concrete guidance regarding therapy, avenues we are pursuing in ongoing research.

Rhythm disturbances as a potential early marker of Parkinson's disease in idiopathic REM sleep behavior disorder.

ObjectiveWe aimed to identify timing distortions in production and perception of rhythmic events in patients with idiopathic REM sleep behavior disorder (iRBD) as early markers of Parkinson's disease (PD).MethodsRhythmic skills, clinical characteristics, dysautonomia, depression, and olfaction were compared in 97 participants, including 21 participants with iRBD, 38 patients with PD, and 38 controls, matched for age, gender, and education level. Rhythmic disturbances can be easily detected with dedicated motor tasks via a tablet application. Rhythm production was tested in two conditions: to examine the ability to generate a spontaneous endogenous rhythm, tapping rate and variability in a finger tapping task without external stimulation was measured, while the ability to synchronize to an external rhythm was tested with finger tapping to external auditory cues. Rhythm perception was measured with a task, in which the participants had to detect a deviation from a regular rhythm. Participants with iRBD had dopamine transporter imaging.ResultsParticipants with iRBD and PD revealed impaired spontaneous rhythm production and poor rhythm perception compared to controls. Impaired rhythm production was correlated with olfaction deficits, dysautonomia, impaired non‐motor aspects of daily living, and dopamine uptake measures.ConclusionsParticipants with iRBD show impaired rhythm production and perception; this impairment is correlated with other early markers for PD. Testing rhythmic skills with short and inexpensive tests may be promising for screening for potential future PD in iRBD patients.

Frequency-specific alternations in the moment-to-moment BOLD signals variability in schizophrenia.

Variability of neuronal activity is considered as the fundamental mechanism for the flexible and optimal brain function. Moreover, different frequency neuro signal is related to specific function. While little is currently known regarding changes in spontaneous BOLD variability of schizophrenia. The current study used resting-state fMRI data from 53 chronic schizophrenic subjects and 67 healthy subjects to investigate this issue. The data-driven method was used to measure the BOLD variability (MSSD: mean square successive difference) in two different frequency bands respectively (slow-5: 0.01-0.027Hz; slow-4:0.027-0.073Hz). Schizophrenic subjects exhibited decreased BOLD variability in thalamus region, sensorimotor and visual networks, and increased BOLD variability in salience network compared to matched healthy controls. Moreover, the interaction effects between frequency and group were observed in thalamus and right dorsolateral prefrontal cortex (DLPFC). These findings identified that altered BOLD variability is frequency dependent in schizophrenia. Importantly, the severity of patients' negative symptom was related to the increased BOLD variability of DLPFC within slow-4 frequency band, highlighting the evidence that abnormal BOLD variability of frontal cortex is likely to have effects on the pathophysiology of negative symptom in schizophrenia.

Dynamical interaction between heart rate and blood pressure of end-stage renal disease patients evaluated by cross recurrence plot diagonal analysis.

The assessment of spontaneous variability of blood pressure and heart rate is based on specific physiological hypotheses about dynamic features, for example, the baroreflex modulation of heart rate over time in daily life. Usually, arterial baroreflex control of heart rate is explored without delays between blood pressure and heart rate data points, within a narrow range of values, excluding the analysis of saturation regions or low-threshold changes. In this work, we examine the dynamic interactions between systolic blood pressure (SBP) and interbeat interval (IBI), in 15-min length time series and for the first time using the analysis of diagonals derived from a cross-recurrence plots in healthy persons and end-stage renal disease (ESRD) patients. We found that ESRD patients have stronger intermittent dynamical interactions between IBI and SBP, but they lose most of the dynamical interactions. Although healthy subjects exhibit a continuously changing order of precedence between IBI and SBP at different lags, ESRD patients preserve this changing order of precedence only for lags >0 beats.NEW & NOTEWORTHY This study is the first to compare the time-variant pattern of systolic blood pressure (SBP) and interbeat interval (IBI) coupling between ESRD patients and healthy volunteers through the analysis of diagonal in cross-recurrence plots, and in the face of an orthostatic challenge. Our results demonstrated alternant interactions on the order of precedence (IBI → SBP or SBP→ IBI) at different time delays. This pattern is different in resting position and during active standing for the two groups studied, and interestingly, some association patterns are lost in ESRD patients. These patterns of alternant interactions on the order of precedence could be related to autonomic neural activities and cardiovascular synchronization at different scales both in time and space. This could reflect physiological adaptive flexibility of cardiovascular regulation. Losing some association patterns in ESRD may be the result of chronic adjustments of many physiological mechanisms (including chronic sympathetic hyperactivity), which could increase cardiovascular vulnerability to hemodynamic challenges.

BOLD and EEG signal variability at rest differently relate to aging in the human brain

Variability of neural activity is regarded as a crucial feature of healthy brain function, and several neuroimaging approaches have been employed to assess it noninvasively. Studies on the variability of both evoked brain response and spontaneous brain signals have shown remarkable changes with aging but it is unclear if the different measures of brain signal variability – identified with either hemodynamic or electrophysiological methods – reflect the same underlying physiology. In this study, we aimed to explore age differences of spontaneous brain signal variability with two different imaging modalities (EEG, fMRI) in healthy younger (25 ​± ​3 years, N ​= ​135) and older (67 ​± ​4 years, N ​= ​54) adults. Consistent with the previous studies, we found lower blood oxygenation level dependent (BOLD) variability in the older subjects as well as less signal variability in the amplitude of low-frequency oscillations (1–12 ​Hz), measured in source space. These age-related reductions were mostly observed in the areas that overlap with the default mode network. Moreover, age-related increases of variability in the amplitude of beta-band frequency EEG oscillations (15–25 ​Hz) were seen predominantly in temporal brain regions. There were significant sex differences in EEG signal variability in various brain regions while no significant sex differences were observed in BOLD signal variability. Bivariate and multivariate correlation analyses revealed no significant associations between EEG- and fMRI-based variability measures. In summary, we show that both BOLD and EEG signal variability reflect aging-related processes but are likely to be dominated by different physiological origins, which relate differentially to age and sex.

The manifold structure of limb coordination in walking Drosophila.

Terrestrial locomotion requires animals to coordinate their limb movements to efficiently traverse their environment. While previous studies in hexapods have reported that limb coordination patterns can vary substantially, the structure of this variability is not yet well understood. Here, we characterized the symmetric and asymmetric components of variation in walking kinematics in the genetic model organism Drosophila. We found that Drosophila use a single continuum of coordination patterns without evidence for preferred configurations. Spontaneous symmetric variability was associated with modulation of a single control parameter-stance duration-while asymmetric variability consisted of small, limb-specific modulations along multiple dimensions of the underlying symmetric pattern. Commands that modulated walking speed, originating from artificial neural activation or from the visual system, evoked modulations consistent with spontaneous behavior. Our findings suggest that Drosophila employ a low-dimensional control architecture, which provides a framework for understanding the neural circuits that regulate hexapod legged locomotion.

Characterization of the Asymmetry of the Cardiac and Sympathetic Arms of the Baroreflex From Spontaneous Variability During Incremental Head-Up Tilt.

Hysteresis of the baroreflex (BR) is the result of the different BR sensitivity (BRS) when arterial pressure (AP) rises or falls. This phenomenon has been poorly studied and almost exclusively examined by applying pharmacological challenges and static approaches disregarding causal relations. This study inspects the asymmetry of the cardiac BR (cBR) and vascular sympathetic BR (sBR) in physiological closed loop conditions from spontaneous fluctuations of physiological variables, namely heart period (HP) and systolic AP (SAP) leading to the estimation of cardiac BRS (cBRS) and muscle sympathetic nerve activity (MSNA) and diastolic AP (DAP) leading to the estimation of vascular sympathetic BRS (sBRS). The assessment was carried out in 12 young healthy subjects undergoing incremental head-up tilt with table inclination gradually increased from 0 to 60°. Two analytical methods were exploited and compared, namely the sequence (SEQ) and phase-rectified signal averaging (PRSA) methods. SEQ analysis is based on the detection of joint causal schemes representing the HP and MSNA burst rate delayed responses to spontaneous SAP and DAP modifications, respectively. PRSA analysis averages HP and MSNA burst rate patterns after aligning them according to the direction of SAP and DAP changes, respectively. Since cBRSs were similar when SAP went up or down, hysteresis of cBR was not detected. Conversely, hysteresis of sBR was evident with sBRS more negative when DAP was falling than rising. sBR hysteresis was no longer visible during sympathetic activation induced by the orthostatic challenge. These results were obtained via the SEQ method, while the PRSA technique appeared to be less powerful in describing the BR asymmetry due to the strong association between BRS estimates computed over positive and negative AP variations. This study suggests that cBR and sBR provide different information about the BR control, sBR exhibits more relevant non-linear features that are evident even during physiological changes of AP, and the SEQ method can be fruitfully exploited to characterize the BR hysteresis with promising applications to BR branches different from cBR and sBR.

Antioxidant Effect of Resveratrol on Autonomic Cardiocirculatory Control in Heart Failure Rats

In animal models of heart failure (HF), resveratrol (RESV) reduced the disease progression and increased the survival rate. Nevertheless, there are no reports in the literature about the effect of RESV on autonomic cardiocirculatory control during the establishment of HF. This study aimed to evaluate the antioxidant effect of RESV on the cardiac autonomic balance and baroreflex sensitivity of HF rats induced by myocardial infarction (MI). Wistar rats were divided into the following groups: Control; Control + RESV; HF; HF + RESV (10mg/kg/day, p.o.). The MI‐induced HF model was produced by ligation of the coronary artery. After four weeks, the animals were anaesthetized for femoral artery and vein catheterization and, 24 hours later, recordings were carried out in conscious animals. Baseline arterial pressure and heart rate (HR, bpm) were recorded during 30 minutes to assess spontaneous baroreflex sensitivity and HR variability. Phenylephrine and sodium nitroprusside (NPS), and methylatropine and propranolol were used for baroreflex evaluation and estimation of cardiac parasympathetic and sympathetic tone, respectively. At the end of the experiments, the animals were anaesthetized to evaluate the cardiac function, using the intraventricular pressure curve, and to withdraw the heart for calculation of heart weight/body weight ratio (HW/BW, mg/g) and the infarct size. The oxidative stress was assessed by measurement of thiobarbituric acid reactive substances (TBARS) in plasma samples. HF and HF+RESV showed 41±3% and 35±3% of infarct size, respectively, and HW/BW ratio increase (3.9±0.1 vs 3.7±0.2 vs 3.0±0.07). HF rats exhibited higher HR compared to control animals (374±12 vs 333±6). RESV did not alter basal parameters in the control group but prevented HR alterations in HF+RESV group (337±6). HF blunted baroreflex sensitivity to phenylephrine (1.3±0.2 vs 2.3±0.3) and NPS (−3.9±0.5 vs −6.0±0.6), increased cardiac sympathetic tone (−44±9 vs −20±4) and decreased parasympathetic tone (54±12 vs 120±7), intrinsic HR (381±8 vs. 401±5), baroreflex effectiveness index (0.06±0.01 vs 0.15±0.01) and LF/HF ratio (0.17±0.05 vs 0.43±0.06). RESV hampered alterations in baroreflex function and cardiac vagal tone (103±13), improve HR variability indexes (LF/HF: 0.3±0.07) and reduced sympathetic control of HR (−29±3) and intrinsic HR in HF+RESV group (360±9). In cardiac function, RESV improved the maximal slope of the systolic increment of left ventricular pressure in HF animals (9004±1120 vs 5956±605 vs 6914±581 mmHg/s). HF increased TBARS compared to control, whereas RESV produced an antioxidant effect in HF+RESV group (11.2±0.9 vs 21.7±3 vs 8.2±1.4 μmol/L). In conclusion, the antioxidant effect of RESV counteracts the cardiovascular autonomic dysfunction and improves systolic left ventricle function during the onset of HF.Support or Funding InformationCNPq e UnaerpThis abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Atmospheric Variability Driven by Radiative Cloud Feedback in Brown Dwarfs and Directly Imaged Extrasolar Giant Planets

Growing observational evidence has suggested active meteorology in atmospheres of brown dwarfs (BDs) and directly imaged extrasolar giant planets (EGPs). In particular, a number of surveys have shown that near-IR brightness variability is common among L and T dwarfs. Despite initial understandings of atmospheric dynamics which is the major cause of the variability by previous studies, the detailed mechanism of variability remains elusive, and we need to seek a natural, self-consistent mechanism. Clouds are important in shaping the thermal structure and spectral properties of these atmospheres via large opacity, and we expect the same for inducing atmospheric variability. In this work, using a time-dependent one-dimensional model that incorporates a self-consistent coupling between the thermal structure, convective mixing, cloud radiative heating/cooling and condensation/evaporation of clouds, we show that radiative cloud feedback can drive spontaneous atmospheric variability in both temperature and cloud structure in conditions appropriate for BDs and directly imaged EGPs. The typical periods of variability are one to tens of hours with typical amplitude of the variability up to hundreds of Kelvins in effective temperature. The existence of variability is robust over a wide range of parameter space, but the detailed evolution of variability is sensitive to model parameters. Our novel, self-consistent mechanism has important implications for the observed flux variability of BDs and directly imaged EGPs, especially those evolve in short timescales. It is also a promising mechanism for cloud breaking, which has been proposed to explain the L/T transition of brown dwarfs.

Resting-State Neural Firing Rate Is Linked to Cardiac-Cycle Duration in the Human Cingulate and Parahippocampal Cortices.

Stimulation and functional imaging studies have revealed the existence of a large network of cortical regions involved in the regulation of heart rate. However, very little is known about the link between cortical neural firing and cardiac-cycle duration (CCD). Here, we analyze single-unit and multiunit data obtained in humans at rest, and show that firing rate covaries with CCD in 16.7% of the sample (25 of 150). The link between firing rate and CCD was most prevalent in the anterior medial temporal lobe (entorhinal and perirhinal cortices, anterior hippocampus, and amygdala), where 36% (18 of 50) of the units show the effect, and to a lesser extent in the mid-to-anterior cingulate cortex (11.1%, 5 of 45). The variance in firing rate explained by CCD ranged from 0.5 to 11%. Several lines of analysis indicate that neural firing influences CCD, rather than the other way around, and that neural firing affects CCD through vagally mediated mechanisms in most cases. These results show that part of the spontaneous fluctuations in firing rate can be attributed to the cortical control of the cardiac cycle. The fine tuning of the regulation of CCD represents a novel physiological factor accounting for spontaneous variance in firing rate. It remains to be determined whether the “noise” introduced in firing rate by the regulation of CCD is detrimental or beneficial to the cognitive information processing carried out in the parahippocampal and cingulate regions.SIGNIFICANCE STATEMENT Fluctuations in heart rate are known to be under the control of cortical structures, but spontaneous fluctuations in cortical firing rate, or “noise,” have seldom been related to heart rate. Here, we analyze unit activity in humans at rest and show that spontaneous fluctuations in neural firing in the medial temporal lobe, as well as in the mid-to-anterior cingulate cortex, influence heart rate. This phenomenon was particularly pronounced in the entorhinal and perirhinal cortices, where it could be observed in one of three neurons. Our results show that part of spontaneous firing rate variability in regions best known for their cognitive role in spatial navigation and memory corresponds to precise physiological regulations.

THE CONNECTION OF THE KARIOTYPE AND REVERSING ABILITY COWS OF THE UKRAINIAN BLACK AND WHEAT DAIRY BREEDS

The aim of research: Studing cariotype conducted cows of Ukrainian Black-and-White dairy breeds and installed corelation conection between cariotype instability and reproduction ability.&#x0D; Methods of research: Сytogenetic – analysis of metaphase plates, peripheral blood cells cows of Ukrainian Black-and-White dairy breeds, micronucleus test-reaction of the organism on mutagenic factors of different nature, zootechnical – analysis of reproductive properties of animals Ukrainian Black-and-White dairy breeds, statistical.&#x0D; Research result: Cariotype analis of Ukrainian Black-and-White dairy breeds (30 heads) farm husbandry “Progress +” showed the following results: control of spontaneous mytagenesis in cows wich was reserch showing quantitative and structural chromosomal aberation. Quantative chromosomal aberationwas find as aneuploidy. Aneuploidy was equal to 7,4% which does not exceed the limits of spontaneous chromosomal variability(1,5–8,3%), what is normal for animals of milk production breeds. Cellular frequency with asynchronous difference centroid chromosomal areas i population of cows at husbandry “Progress +” was 1,05% and did not exceed the spontaneous cytogenetic variability characteristic for the species Bostaurus. The share of metaphase plates with structural chromosomal abnormalities (chromosomal breaks) 2,6% equal to the level of spontaneous chromosomal variability for cows (0,17–11,1%). Cellular cell with micro nucleus and dual core lymphocytes was within the spontaneous level, characteristic of mammals, which were kept in the absence of direct genotoxic effects and amounted to 3.7‰ and 2.3‰, respectively. To install associate conection between chromosomal abnormalities and the reproductive ability of the studied cows was carried out a correlation analysis. Received coefficient between dual-core lymphocytes and age 1 calving (r = -0,9585) indicates a negative correlation with the strength of communication according to the Student's criteria isreliable at P &gt; 0.99.&#x0D; Conclusions: Quantitative chromosomal aberrations (aneuploidy) were 7.4% which does not exceed the limit of spontaneous chromosomal variability, characteristic for animals breeds of milk production.&#x0D; The frequency of cells with asynchronous difference is established centroid chromosomal areas – 1,05% and a fraction of metaphase plates – 2,6% which corresponds to the level of spontaneous chromosomal variability in cattle.&#x0D; Detected сell frequency with micro nucleus and dual core lymphocytes which were within the spontaneous level, characteristic of mammals which are kept in the absence of direct genotoxic effects and amounted to 3.7‰ and 2.3‰.&#x0D; Was detected a negative correlation relationship between dual-core lymphocytes and age of the 1 calving (r = -0.9585, P &gt; 0.99).

Dynamic cerebral autoregulation after confinement in an isolated environment for 14\u2009days

BackgroundTo develop human space exploration, it is necessary to study the effects of an isolated and confined environment, as well as a microgravity environment, on cerebral circulation. However, no studies on cerebral circulation in an isolated and confined environment have been reported. Therefore, we investigated the effects of a 14-day period of confinement in an isolated environment on dynamic cerebral autoregulation.MethodsWe participated in an isolation and confinement experiment conducted by the Japan Aerospace Exploration Agency in 2016. Eight healthy males were isolated and confined in a facility for 14 days. Data were collected on the days immediately before and after confinement. Arterial blood pressure waveforms were obtained using a finger blood pressure monitor, and cerebral blood flow velocity waveforms in the middle cerebral artery were obtained using transcranial Doppler ultrasonography for 6 min during quiet rest in a supine position. Dynamic cerebral autoregulation was evaluated by transfer function analysis between spontaneous variability of beat-to-beat mean arterial blood pressure and mean cerebral blood flow velocity.ResultsTransfer function gain in the low- and high-frequency ranges increased significantly (0.54 ± 0.07 to 0.69 ± 0.09 cm/s/mmHg and 0.80 ± 0.05 to 0.92 ± 0.09 cm/s/mmHg, respectively) after the confinement.ConclusionThe increases observed in transfer function gain may be interpreted as indicating less suppressive capability against transmission from arterial blood pressure oscillation to cerebral blood flow velocity fluctuation. These results suggest that confinement in an isolated environment for 14 days may impair dynamic cerebral autoregulation.Trial registrationUMIN000020703, Registered 2016/01/22.

Testing the vagal withdrawal hypothesis during light exercise under autonomic blockade: a heart rate variability study.

We performed the first analysis of heart rate variability (HRV) at rest and during exercise under full autonomic blockade on the same subjects, to test the conjecture that vagal tone withdrawal occurs at exercise onset. We hypothesized that between rest and exercise there would be 1) no differences in total power (PTOT) under parasympathetic blockade, 2) a PTOT fall under β1-sympathetic blockade, and 3) no differences in PTOT under blockade of both autonomic nervous system branches. Seven men [24 (3) yr, mean (SD)] performed 5-min cycling (80 W) supine, preceded by 5-min rest during control and with administration of atropine, metoprolol, and atropine + metoprolol (double blockade). Heart rate and arterial blood pressure were continuously recorded. HRV and blood pressure variability were determined by power spectral analysis, and baroreflex sensitivity was determined by the sequence method. At rest, PTOT and the powers of low- and high-frequency components of HRV (LF and HF, respectively) were dramatically decreased with atropine and double blockade compared with control and metoprolol, with no effects on LF-to-HF ratio and on the normalized LF (LFnu) and HF (HFnu). During exercise, patterns were the same as at rest. Comparing exercise with rest, PTOT varied as hypothesized. For systolic and diastolic blood pressure, resting PTOT was the same in all conditions. During exercise, in all conditions, PTOT was lower than in control. Baroreflex sensitivity decreased under atropine and double blockade at rest and under control and metoprolol during exercise. The results support the hypothesis that vagal suppression determined disappearance of HRV during exercise.NEW & NOTEWORTHY This study provides the first demonstration, by systematic analysis of heart rate variability at rest and during exercise under full autonomic blockade on the same subjects, that suppression of vagal activity is responsible for the disappearance of spontaneous heart rate variability during exercise. This finding supports previous hypotheses on the role of vagal withdrawal in the control of the rapid cardiovascular response at exercise onset.