Impact of Flaxseed Oil Supplementation on Tobacco Dependence, Craving, and Haematological Parameters in Tobacco-Dependent Subjects.

Background Tobacco is prevalently used in smoking or smokeless forms and remains a major public health concern worldwide, with its adverse effects on overall health. Omega-3 fatty acid (FA) has shown its promising effects in various health conditions. Objective The purpose of this study was to evaluate the effect of flaxseed oil (omega-3 supplementation) on tobacco dependence, craving, withdrawal symptoms, and haematological parameters in tobacco users. Methods In this randomised, single-blind, placebo-controlled study, 104 tobacco users (54 in the omega-3 group and 50 in the placebo group) were supplemented with 10 ml of food-grade flaxseed oil and 10 ml of placebo for six months, respectively. Their demographics, frequency of daily tobacco use, tobacco dependence, tobacco craving, tobacco withdrawal symptoms, and complete blood count (CBC) were assessed at baseline (before intervention) and after a six-month intervention. Results The demographic characteristics of the two groups were similar except for gender at baseline. There were 50 males and four females in the omega-3 group, while there were 42 males and eight females in the placebo group. After a six-month flaxseed oil intervention, BMI values showed a significant reduction (p = 0.0081) in the omega-3 group when compared to baseline; however, CBC parameters did not show any significant changes when comparing baseline to follow-up values. On the contrary, haemoglobin and red blood cells (RBCs) showed significant changes when comparing the follow-ups of the omega-3 group with the placebo group, indicating p = 0.0016 and p = 0.0163, respectively. Also, omega-3 effectively decreased daily tobacco use frequency (p<0.0001), tobacco dependence (p<0.0001), and craving (p<0.0001). Conclusion Supplementation of 10 ml of flaxseed oil per day (omega-3 FA) for six months significantly reduced tobacco dependence and cravings. Additionally, the flaxseed oil supplementation effectively reduced the frequency of daily tobacco intake and modulated tobacco withdrawal symptoms. Thus, our results suggest that flaxseed oil supplementation is a useful adjunct for tobacco users who intend to quit tobacco use.

Slow-wave sleep dysfunction in mild parkinsonism is associated with excessive beta and reduced delta oscillations in motor cortex.

Increasing evidence suggests slow-wave sleep (SWS) dysfunction in Parkinson's disease (PD) is associated with faster disease progression, cognitive impairment, and excessive daytime sleepiness. Beta oscillations (8-35 Hz) in the basal ganglia thalamocortical (BGTC) network are thought to play a role in the development of cardinal motor signs of PD. The role cortical beta oscillations play in SWS dysfunction in the early stage of parkinsonism is not understood, however. To address this question, we used a within-subject design in a nonhuman primate (NHP) model of PD to record local field potentials from the primary motor cortex (MC) during sleep across normal and mild parkinsonian states. The MC is a critical node in the BGTC network, exhibits pathological oscillations with depletion in dopamine tone, and displays high amplitude slow oscillations during SWS. The MC is therefore an appropriate recording site to understand the neurophysiology of SWS dysfunction in parkinsonism. We observed a reduction in SWS quantity (p = 0.027) in the parkinsonian state compared to normal. The cortical delta (0.5-3 Hz) power was reduced (p = 0.038) whereas beta (8-35 Hz) power was elevated (p = 0.001) during SWS in the parkinsonian state compared to normal. Furthermore, SWS quantity positively correlated with delta power (r = 0.43, p = 0.037) and negatively correlated with beta power (r = -0.65, p < 0.001). Our findings support excessive beta oscillations as a mechanism for SWS dysfunction in mild parkinsonism and could inform the development of neuromodulation therapies for enhancing SWS in people with PD.

Exploring the Relation Between Interstitial Lung Diseases and Chronic Periodontitis: A Systematic Review.

The objective of this systematic review is to determine the association between interstitial lung diseases and chronic periodontitis from various aspects such as microbial, biomarker, genetic, and environmental levels. A systematic review was carried out from 2000 to 2021 following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) recommendations including studies searched in PubMed-Medline, Google Scholar, and Cochrane databases. A total of more than 100 articles were obtained in the initial screening process. Out of these 42 studies fulfilled the inclusion criteria and were included in the study. According to the extracted data, there is mounting evidence suggesting the association between these two diseases. Our systematic review raises the prospect of a connection between chronic periodontitis and interstitial lung diseases, within the limitations of the studies we included.

Classification of bruxism based on time-frequency and nonlinear features of single channel EEG.

BACKGROUND: In the classification of bruxism patients based on electroencephalogram (EEG), feature extraction is essential. The method of using multi-channel EEG fusing electrocardiogram (ECG) and Electromyography (EMG) signal features has been proved to have good performance in bruxism classification, but the classification performance based on single channel EEG signal is still understudied. We investigate the efficacy of single EEG channel in bruxism classification. METHODS: We have extracted time-domain, frequency-domain, and nonlinear features from single EEG channel to classify bruxism. Five common bipolar EEG recordings from 2 bruxism patients and 4 healthy controls during REM sleep were analyzed. The time domain (mean, standard deviation, root mean squared value), frequency domain (absolute, relative and ratios power spectral density (PSD)), and non-linear features (sample entropy) of different EEG frequency bands were analyzed from five EEG channels of each participant. Fine tree algorithm was trained and tested for classifying sleep bruxism with healthy controls using five-fold cross-validation. RESULTS: Our results demonstrate that the C4P4 EEG channel was most effective for classification of sleep bruxism that yielded 95.59% sensitivity, 98.44% specificity, 97.84% accuracy, and 94.20% positive predictive value (PPV). CONCLUSIONS: Our results illustrate the feasibility of sleep bruxism classification using single EEG channel and provides an experimental foundation for the development of a future portable automatic sleep bruxism detection system.

Pyopneumothorax Secondary to Pulmonary Tuberculosis Superadded by Congenital Factor XIII Deficiency: A Case Report.

Pyopneumothorax is a rare complication of pulmonary tuberculosis, contributing significantly to morbidity and mortality. Additionally, factor XIII deficiency, a rare bleeding disorder, may pose a diagnostic challenge due to normal results in routine coagulation tests. We present the case of an 18-year-old boy who presented with a history of left-sided pyopneumothorax secondary to drug-sensitive Mycobacterium tuberculosis, complicated by congenital factor XIII deficiency. After three months of intercostal drainage placement, the patient developed severe anemia and bleeding tendencies, necessitating a referral to clinical hematology. Genetic testing revealed factor XIII deficiency. This case highlights the complicated interplay between tuberculosis-related complications and a coexisting genetic disorder, highlighting the importance of comprehensive clinical assessment and multidisciplinary management.

Excessive cortical beta oscillations are associated with slow-wave sleep dysfunction in mild parkinsonism.

Increasing evidence associates slow-wave sleep (SWS) dysfunction with neurodegeneration. Using a within-subject design in the nonhuman primate model of Parkinson's disease (PD), we found that reduced SWS quantity in mild parkinsonism was accompanied by elevated beta and reduced delta power during SWS in the motor cortex. Our findings support excessive beta oscillations as a mechanism for SWS dysfunction and will inform development of neuromodulation therapies for enhancing SWS in PD.

The Effect of Skeletal Muscle-Pump on Blood Pressure and Postural Control in Parkinson's Disease.

PURPOSE: Activation of the calf (gastrocnemius and soleus) and tibialis anterior muscles play an important role in blood pressure regulation (via muscle-pump mechanism) and postural control. Parkinson's disease is associated with calf (and tibialis anterior muscles weakness and stiffness, which contribute to postural instability and associated falls. In this work, we studied the role of the medial and lateral gastrocnemius, tibialis anterior, and soleus muscle contractions in maintaining blood pressure and postural stability in Parkinson's patients and healthy controls during standing. In addition, we investigated whether the activation of the calf and tibialis anterior muscles is baroreflex dependent or postural-mediated. METHODS: We recorded electrocardiogram, blood pressure, center of pressure as a measure of postural sway, and muscle activity from the medial and lateral gastrocnemius, tibialis anterior, and soleus muscles from twenty-six Parkinson's patients and eighteen sex and age-matched healthy controls during standing and with eyes open. The interaction and bidirectional causalities between the cardiovascular, musculoskeletal, and postural variables were studied using wavelet transform coherence and convergent cross-mapping techniques, respectively. RESULTS: Parkinson's patients experienced a higher postural sway and demonstrated mechanical muscle-pump dysfunction of all individual leg muscles, all of which contribute to postural instability. Moreover, our results showed that coupling between the cardiovascular, musculoskeletal, and postural variables is affected by Parkinson's disease while the contribution of the calf and tibialis anterior muscles is greater for blood pressure regulation than postural sway. CONCLUSION: The outcomes of this study could assist in the development of appropriate physical exercise programs that target lower limb muscles to improve the muscle-pump function and reduce postural instability in Parkinson's disease.

Correlation Between Chronic Periodontitis and Lung Cancer: A Systematic Review With Meta-Analysis.

Periodontal disease is associated with many systemic diseases, such as cardiovascular diseases, atherosclerosis, diabetes mellitus, stroke, and pulmonary diseases. Interestingly, recent literature suggests that periodontal disease might be a risk factor for various cancers such as lung, colon, oesophageal, head, and neck cancers. However, the precise mechanistic link is lacking. Hence, in this meta-analysis, we aimed to investigate the correlation between periodontal disease and lung cancer in periodontally diseased patients. Data were searched for relevant studies from 2010 to 2022. We correlated periodontal disease and lung cancer based on adjusted ORs/HRs and associated CIs. I2 statistic was used to assess statistical heterogeneity. Publication bias was analyzed by visually inspecting the symmetry of the funnel plot and Egger's test. The study is registered in the International Prospective Register of Systematic Reviews (PROSPERO; registration no: CRD42023390819). A total of 194,850 participants from observational studies (two case-control studies and five cohort studies) were incorporated for the current analysis. The meta-analysis of included studies showed an overall effect size (risk ratio) of the periodontal disease group with respect to the non-periodontal disease group for lung neoplasm to be 1.41 (95% CI: 1.32-1.52). The value was more than 1, indicating that the periodontal disease group had a relatively higher lung cancer prevalence than the non-periodontal disease group. Further, the overall risk ratio was found to be statistically significant (p<0.00001). Moreover, the funnel plot suggested some degree of publication bias. Evidence in our study implicated that there is an increased risk of occurrence of lung cancer in chronic periodontitis patients.

3D printed guide tube system for acute Neuropixels probe recordings in non-human primates.

Objective.Neuropixels (NP) probes are a significant advance in electrophysiological recording technology that enable monitoring of hundreds of neurons in the brain simultaneously at different depths. Application of this technology has been predominately in rodents, however widespread use in non-human primates (NHPs) such as rhesus macaques has been limited. In this study we sought to overcome two overarching challenges that impede acute NP implantation in NHPs: (1) traditional microdrive systems that mount to cephalic chambers are commonly used to access cortical areas for microelectrode recordings but are not designed to accommodate NP probes, and (2) NHPs have thick dura mater and tissue growth within the cephalic chambers which poses a challenge for insertion of the extremely fragile NP probe.Approach.In this study we present a novel NP guide tube system that can be adapted to commercial microdrive systems and demonstrate an implant method using the NP guide tube system. This system was developed using a combination of CAD design, 3D printing, and small part machining. Software programs, 3D Slicer and SolidWorks were used to target cortical areas, approximate recording depths and locations, and for in-silico implant testing.Main results.We performedin vivotesting to validate our methodology, successfully implanting, explanting, and reimplanting NP probes. We collected stable neurophysiological recordings in the premotor cortex of a rhesus macaque at rest and during performance of a reaching task.Significance.In this study we demonstrate a robust Neuropixels implant system that allows multiple penetrations with the same NP probe and share design files that will facilitate the adoption of this powerful recording technology for NHP studies.

Cardio-respiratory interactions in response to lower-body negative pressure.

The relationship between heart rate and blood pressure, as well as cardiorespiratory coupling, play a critical role in maintaining blood pressure and organ perfusion during conditions of blood loss. Traditional vital signs such as blood pressure, breathing rate, and oxygen saturation are poor markers of blood loss, making it difficult for medics to assess the severity of central hypovolemia. Monitoring hemorrhage is further complicated by the fact that some patients have a low tolerance to hemorrhage and would reach the point of cardiovascular collapse in less time than high tolerant individuals. Therefore, this study aimed to investigate the potential of the physiological interaction between heart rate and blood pressure, and cardiorespiratory coupling to track the progression of simulated hemorrhage, as well as distinguish individuals with low tolerance (LT) from the ones with high tolerance (HT) to hypovolemia. Nineteen subjects (age: 28 ± 6 years; height: 170 ± 7 cm; weight: 68 ± 10 kg) underwent a progressive lower body negative pressure (LBNP) protocol in which the participant was supine inside the chamber for 12 min (baseline) before 12 min of chamber decompression at -20, -30, -40, -50 and -60 mmHg followed by a 12 min recovery period. Twelve subjects reached presyncope before or during -60 mmHg LBNP stage and were considered low tolerant (LT, 12 participants), while the ones who completed -60 mmHg were considered high tolerant (HT, 7 participants). Continuous blood pressure (BP), respiration (RSP), and electrocardiogram (ECG) signals were acquired simultaneously during baseline and each LBNP stage. RR interval was calculated using ECG, while systolic blood pressure (SBP), and pulse pressure were derived from BP waveform. Wavelet transform coherence and convergent cross-mapping techniques were employed to study the physiological interdependence and the causal relationship between heart rate, blood pressure, and respiration. The interaction between blood pressure and heart rate in terms of gain, active gain, and fraction time active(SBP↔RR,PP↔RR)to maintain homeostasis was higher in the LT group during baseline, and LBNP simulated mild, moderate, and severe hemorrhage. The significant time of interaction between SBP and RSP, and the causal effect of blood pressure on respiration were higher in the HT group during baseline compared to the LT group. HT participants also had a higher causal effect of respiration on blood pressure(RSP→SBP,RSP→PP)during -30 and -40 mmHg compared to LT. Moreover, the HT group displayed a higher causal drive of respiratory-related changes in heart rate(RSP→RR)and heart rate mediated changes in respirationRR→RSPduring severe simulated hemorrhage (-40 mmHg) compared to the LT group. The calculated metrics to distinguish between individual LT from HT subjects achieved a sensitivity of 58%-83%, an accuracy of 63%-84%, and an area under the ROC curve of 74%-86%, while the overlap of LT individual responses with HT was 0%-33%. These results indicate the potential of cardiorespiratory coupling, and heart rate and blood pressure interaction toward tracking the progression of hemorrhage and distinguishing individuals with low tolerance to hypovolemia from those with high tolerance. Measurements of such interactions could improve clinical outcomes for patients with low tolerance to hypovolemia and therefore reduce morbidity and mortality through early implementation of life-saving interventions.

Parkinsonian daytime sleep-wake classification using deep brain stimulation lead recordings.

Excessive daytime sleepiness is a recognized non-motor symptom that adversely impacts the quality of life of people with Parkinson's disease (PD), yet effective treatment options remain limited. Deep brain stimulation (DBS) of the subthalamic nucleus (STN) is an effective treatment for PD motor signs. Reliable daytime sleep-wake classification using local field potentials (LFPs) recorded from DBS leads implanted in STN can inform the development of closed-loop DBS approaches for prompt detection and disruption of sleep-related neural oscillations. We performed STN DBS lead recordings in three nonhuman primates rendered parkinsonian by administrating neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). Reference sleep-wake states were determined on a second-by-second basis by video monitoring of eyes (eyes-open, wake and eyes-closed, sleep). The spectral power in delta (1-4 Hz), theta (4-8 Hz), low-beta (8-20 Hz), high-beta (20-35 Hz), gamma (35-90 Hz), and high-frequency (200-400 Hz) bands were extracted from each wake and sleep epochs for training (70% data) and testing (30% data) a support vector machines classifier for each subject independently. The spectral features yielded reasonable daytime sleep-wake classification (sensitivity: 90.68 ± 1.28; specificity: 88.16 ± 1.08; accuracy: 89.42 ± 0.68; positive predictive value; 88.70 ± 0.89, n = 3). Our findings support the plausibility of monitoring daytime sleep-wake states using DBS lead recordings. These results could have future clinical implications in informing the development of closed-loop DBS approaches for automatic detection and disruption of sleep-related neural oscillations in people with PD to promote wakefulness.

Basal ganglia engagement during REM sleep movements in Parkinson's disease.

To elucidate the role of the basal ganglia during REM sleep movements in Parkinson's disease (PD) we recorded pallidal neural activity from four PD patients. Unlike desynchronization commonly observed during wakeful movements, beta oscillations (13-35 Hz) synchronized during REM sleep movements; furthermore, high-frequency oscillations (150-350 Hz) synchronized during movement irrespective of sleep-wake states. Our results demonstrate differential engagement of the basal ganglia during REM sleep and awake movements.

Effect of Parkinson's Disease on Cardio-postural Coupling During Orthostatic Challenge.

Cardiac baroreflex and leg muscles activation are two important mechanisms for blood pressure regulation, failure of which could result in syncope and falls. Parkinson's disease is known to be associated with cardiac baroreflex impairment and skeletal muscle dysfunction contributing to falls. However, the mechanical effect of leg muscles contractions on blood pressure (muscle-pump) and the baroreflex-like responses of leg muscles to blood pressure changes is yet to be comprehensively investigated. In this study, we examined the involvement of the cardiac baroreflex and this hypothesized reflex muscle-pump function (cardio-postural coupling) to maintain blood pressure in Parkinson's patients and healthy controls during an orthostatic challenge induced via a head-up tilt test. We also studied the mechanical effect of the heart and leg muscles contractions on blood pressure. We recorded electrocardiogram, blood pressure and electromyogram from 21 patients with Parkinson's disease and 18 age-matched healthy controls during supine, head-up tilt at 70°, and standing positions with eyes open. The interaction and bidirectional causalities between the cardiovascular and musculoskeletal signals were studied using wavelet transform coherence and convergent cross mapping techniques, respectively. Parkinson's patients displayed an impaired cardiac baroreflex and a reduced mechanical effect of the heart on blood pressure during supine, tilt and standing positions. However, the effectiveness of the cardiac baroreflex decreased in both Parkinson's patients and healthy controls during standing as compared to supine. In addition, Parkinson's patients demonstrated cardio-postural coupling impairment along with a mechanical muscle pump dysfunction which both could lead to dizziness and falls. Moreover, the cardiac baroreflex had a limited effect on blood pressure during standing while lower limb muscles continued to contract and maintain blood pressure via the muscle-pump mechanism. The study findings highlighted altered bidirectional coupling between heart rate and blood pressure, as well as between muscle activity and blood pressure in Parkinson's disease. The outcomes of this study could assist in the development of appropriate physical exercise programs to reduce falls in Parkinson's disease by monitoring the cardiac baroreflex and cardio-postural coupling effect on maintaining blood pressure.

Prevalence of obstructive sleep apnea in diabetic patients.

Context: Obstructive sleep apnea (OSA)-related hypoxemia stimulates release of acute-phase proteins and reactive oxygen species that exacerbate insulin resistance and lipolysis and cause an augmented prothrombotic and proinflammatory state which can leads to premature death. Aims: This study aims to study the prevalence of OSA in diabetic patients. Setting and Design: It was a cross-sectional study, done over a period of 1 year in a tertiary care hospital. Materials and Methods: A total of 149 type 2 diabetic patients were enrolled after taking written consent. All patients were subjected to STOP BANG questionnaire and patients falling in intermediate-high risk (score 3-8), were taken for overnight polysomnography to confirm the diagnosis of OSA (apnea hypopnea index ≥ 5). Statistical Analysis Used: Statistical Package for Social Sciences (SPSS) Version 21.0 statistical analysis software. Results: Fifty-five percent of our diabetic population were having OSA. The age of patients enrolled in the study ranged between 30 and 86 years and prevalence increases with an increase in age groups. Majority (61.7%) of our cases were males. Incremental trend in weight, body mass index (BMI), neck circumference, and waist circumference of OSA cases were found with increasing in severity of OSA. Mean levels of raised blood sugar and HbA1c were higher in severe OSA cases. Conclusions: OSA has a high prevalence in patients with type 2 diabetes mellitus. Patients with type 2 diabetes should be screened for OSA, even in the absence of symptoms, especially in individuals with higher waist circumference and BMI.

RésuméContexte: L'hypoxémie liée à l'apnée obstructive du sommeil (AOS) stimule la libération de protéines de phase aiguë et d'espèces réactives de l'oxygène qui exacerber la résistance à l'insuline et la lipolyse et provoquer un état prothrombotique et pro-inflammatoire accru qui peut conduire à un décès. Objectifs: Cette étude vise à étudier la prévalence de l'AOS chez les patients diabétiques. Cadre et conception: il s'agissait d'une étude transversale, réalisée sur une période d'un an dans un hôpital de soins tertiaires. Matériels et méthodes: Un total de 149 patients diabétiques de type 2 ont été recrutés après avoir pris consentement écrit. Tous les patients ont été soumis au questionnaire STOP BANG et les patients à risque intermédiaire-élevé (score 3-8), ont été prise pour une polysomnographie nocturne pour confirmer le diagnostic d'AOS (index d'apnée hypopnée ≥ 5). Analyse statistique utilisée: statistique Package for Social Sciences (SPSS) Version 21.0 du logiciel d'analyse statistique. Résultats: Cinquante-cinq pour cent de notre population diabétique étaient souffrant d'AOS. L'âge des patients inclus dans l'étude variait entre 30 et 86 ans et la prévalence augmente avec l'augmentation des tranches d'âge. La majorité (61,7 %) de nos cas étaient des hommes. Tendance progressive du poids, de l'indice de masse corporelle (IMC), du tour de cou et du tour de taille des cas d'AOS ont été trouvés avec une augmentation de la sévérité de l'AOS. Les taux moyens de glycémie élevée et d'HbA1c étaient plus élevés dans les cas graves d'AOS. Conclusions: L'AOS a une prévalence élevée chez les patients atteints de diabète de type 2. Les patients atteints de diabète de type 2 doivent subir un dépistage de l'AOS, même en l'absence de symptômes, en particulier chez les personnes ayant un tour de taille et un IMC plus élevés.

Remdesivir - Current evidence & perspective in management of COVID-19 infection.

Coronavirus infection or COVID 19 was first reported in December 2019 in Wuhan, China, and has rapidly spread to more than 200 countries. The pandemic has also taken a toll of over 2.2 million. But the elusive search for an effective antidote is still on. Pending multiple and robust randomized controlled studies, some drugs are being used globally based on in-vitro studies, in -vivo evidence, observational studies, and small nonrandomized studies. Remdesivir is a nucleotide analog. It inhibits viral RNA-dependent RNA polymerase enzyme. Several studies have hitherto demonstrated the promising in-vitro and in-vivo antiviral activities of the molecule against severe acute respiratory syndrome coronavirus (SARS-CoV-1) and the Middle East respiratory syndrome coronavirus (MERS-CoV) strains. It has now exhibited potential in vitro activity against SARS-CoV-2 strains too. Based on pivotal studies, remdesivir is now being used to treat moderate to severe patients through emergency use authorizations and other access programs around the world. This review aims to summarize the evidence and clinical trials of remdesivir as a potential therapeutic option for COVID-19.

An update on the diagnostic biomarkers for asthma.

Asthma is a respiratory disorder accounts for ~339 million cases per annum. The initial diagnosis of asthma relies on the symptomatic identification of characters, such as wheeze, shortness of breath, chest tightness, and cough. The presence of two or more of these symptoms may be considered as indicative of asthma. The asthma-diagnostic also involves spirometry test before and after inhaling a bronchodilator like albuterol. Because asthma pathophysiology involves participation of immune system, the cytokines play an important role. The review discusses various molecules that are or may be used as biomarkers for the asthma diagnosis.

Cardio-postural interactions and muscle-pump baroreflex are severely impacted by 60-day bedrest immobilization.

To understand fundamental mechanisms associated with post-flight orthostatic intolerance we investigated the interaction between the cardiovascular and postural functions before and after 60 days of head down bedrest (HDBR). Twenty healthy young males (35.0 ± 1.7 years) were subjected to 60-day HDBR at 6˚ to simulate spaceflight-induced fluid shifts. A supine-to-stand (STS) test was conducted to evaluate cardio-postural control before and after (R) HDBR while an assessment of cardiovascular function was performed during HDBR. Beat-to-beat heart period, systolic blood pressure, and electromyography impulses were derived for wavelet transform coherence and causality analyses of the cardio-postural control and used to assess changes in the muscle-pump baroreflex. During quiet stand of the STS test, compared to baseline, heart rate was 50% higher on the day of exit from bedrest (R0) and 20% higher eight days later (R8). There was a 50% increase in deoxygenated hemoglobin on R0 and R8. Leg muscle activity reduced, and postural sway increased after HDBR. Causality of the muscle-pump baroreflex was reduced on R0 (0.73 ± 0.2) compared to baseline (0.87 ± 0.2) with complete recovery by R8. The muscle-pump baroreflex also had decreased gain and fraction time active following HDBR. Overall, our data show a significantly impaired muscle-pump baroreflex following bedrest.

Effect of Aging on Muscle-Pump Baroreflex of Individual Leg Muscles During Standing.

Activation of leg muscles is an important component in the regulation of blood pressure during standing, failure of which could result in syncope and falls. Our previous work demonstrated baroreflex mediated activation of leg muscles (muscle-pump baroreflex) as an important factor in the regulation of blood pressure during standing; however, the effect of aging on the muscle-pump baroreflex of individual leg muscles during standing remains to be understood. Here, the interaction between systolic blood pressure (SBP) and the activation of lateral gastrocnemius (LG), medial gastrocnemius (MG), tibialis anterior (TA), and soleus (SOL) muscles during standing was quantified. Beat-to-beat heart period (RR interval), SBP, electromyography impulse (EMGimp) were derived from continuously acquired electrocardiography, finger blood pressure, and calf-electromyography, respectively. The cardiac baroreflex (SBP→RR) causality (0.88 ± 0.08 vs. 0.94 ± 0.03, p = 0.01), percent time with significant coherence (%SC: 50.95 ± 23.31 vs. 76.75 ± 16.91, p = 0.001), and gain (4.39 ± 4.38 vs. 13.05 ± 8.11, p < 0.001) was lower in older (69 ± 4 years) compared to young (26 ± 2 years) persons. Muscle-pump baroreflex (SBP→EMGimp) causality of LG (0.81 ± 0.08 vs. 0.88 ± 0.05, p = 0.01) and SOL (0.79 ± 0.11 vs. 0.88 ± 0.04, p = 0.01) muscles was lower in older compared to young persons. %SC was lower for all muscles in the older group (LG, p < 0.001; MG, p = 0.01; TA, p = 0.01; and SOL, p < 0.001) compared to young. The study outcomes highlighted impairment in muscle-pump baroreflex with age in addition to cardiac baroreflex. The findings of the study can assist in the development of an effective system for monitoring orthostatic tolerance via cardiac and muscle-pump baroreflexes to mitigate syncope and falls.

Relationship between Ischemic Stroke and Pulse Rate Variability as a Surrogate of Heart Rate Variability.

Autonomic reflex ascertains cardiovascular homeostasis during standing. Impaired autonomic reflex could lead to dizziness and falls while standing; this is prevalent in stroke survivors. Pulse rate variability (PRV) has been utilized in the literature in lieu of heart rate variability (HRV) for ambulatory and portable monitoring of autonomic reflex predominantly in young, healthy individuals. Here, we compared the PRV with gold standard HRV for monitoring autonomic reflex in ischemic stroke survivors. Continuous blood pressure and electrocardiography were acquired from ischemic stroke survivors (64 ± 1 years) and age-matched controls (65 ± 2 years) during a 10-minute sit-to-stand test. Beat-by-beat heart period (represented by RR and peak-to-peak (PP) intervals), systolic blood pressure (SBP), diastolic blood pressure (DBP), and pulse arrival time (PAT), an indicator of arterial stiffness, were derived. Time and frequency domain HRV (from RR intervals) and PRV (from PP intervals) metrics were extracted. PAT was lower (248 ± 7 ms vs. 270 ± 8 ms, p < 0.05) suggesting higher arterial stiffness in stroke survivors compared to controls during standing. Further, compared to controls, the agreement between HRV and PRV was impaired in stroke survivors while standing. The study outcomes suggest that caution should be exercised when considering PRV as a surrogate of HRV for monitoring autonomic cardiovascular control while standing in stroke survivors.