HF Ratio Research Articles

Physiological and behavioral response of foals to hot iron or freeze branding

Branding horses with permanent marks is still a routine for many breeders in many parts of the world. This method of identification is traditionally done with a hot iron, although cold or freeze branding with liquid nitrogen has been widely disseminated as a less painful method. However, there are no studies comparing freeze and hot iron branding related to horses. This study aimed to compare brand quality and autonomic responses (heart rate variability), cortisol levels, and behavioral responses induced by hot branding (hot iron) and freeze branding (liquid nitrogen). Twenty-three foals of pure and crossbreds of Mangalarga Marchador, aged between 20 and 28 weeks, males and females were branded with the symbol 47 (6.5 × 8.5 cm) on the left shoulder. The animals were divided into 2 groups: hot iron (n = 11) and freeze (n = 12) and the twitching lip method was used to restrain the animals during the branding. No differences in cortisol levels were detected between the 2 groups. In the behavioral assessment, only in the hot iron group was one case of kicking and another of rearing observed. Horses in the hot iron group had more limb movements than did those in the freeze group. Our results have shown that hot iron branding has higher autonomic activation than freeze branding, with sympathetic predominance over the parasympathetic activation, as characterized by higher LF/ HF ratio, LF, SDNN/RMSSD ratio, and lower HF. Freeze branding produced fewer wounds and necrosis in the skin with no significant differences in the sharpness of the mark. Freeze branding proved to be a better option than hot iron because it causes less intense autonomic stress responses and fewer open wounds while giving the same sharpness as the hot iron branding. In terms of animal welfare, hot iron branding should be avoided or universally banned.

High-precision Pb and Hf isotope and highly siderophile element abundance systematics of high-MgO Icelandic lavas

Ocean island basalts (OIB) exhibit significant variations in their 87Sr/86Sr, 143Nd/144Nd, 176Hf/177Hf, 186,187Os/188Os, and 206,207,208Pb/204Pb compositions that indicate contributions from multiple mantle sources. To further constrain the relationships between diverse long-lived isotopic systems in OIB, new double-spike Pb and Hf isotope data, as well as isotope dilution highly siderophile element (HSE: Os, Ir, Ru, Pt, Pd, and Re) abundances are reported for nineteen Icelandic picrites and basalts for which 3He/4He, 87Sr/86Sr, 143Nd/144Nd, and 186,187Os/188Os data have been reported previously (Brandon et al., 2007. GCA). Hafnium-Nd-He isotope systematics for the sample set reveal the presence of an ancient refractory source with low-3He/4He, while He-Pb isotope correlations indicate that recycled oceanic crustal components with high-3He/4He added from a less degassed mantle source are present in the Iceland plume. The highly depleted, low-3He/4He signature is sampled in the Northern and Western Volcanic Zones, likely due to higher degrees of partial melting at those localities enabling sampling of this refractory endmember. The 187Os/188Os ratios show correlations with Pb, Hf, and Nd isotope ratios indicating binary mixing between depleted and enriched sources, with no evidence for decoupling due to sulfide metasomatism. The spread of 187Os/188Os- 206,207,208Pb/204Pb data can be explained by addition of 1–11% young recycled oceanic crust to a depleted mantle source distinct from the source of Atlantic MORB. Abundances of the HSE in Northern and Western Volcanic Zone lavas overlap with those from other OIB with similar MgO contents, showing fractionated patterns that are enriched in the more incompatible Re, Pd, and Pt over the compatible Ru, Ir, and Os. Calculated parental melt HSE abundances of those lavas also overlap with those of other OIB. Eastern Volcanic Zone lavas are highly depleted in Pt and Pd relative to other Icelandic lavas. Abundances of Pt and Pd correlate with isotopic parameters, such as 206Pb/204Pb, in Icelandic lavas, indicating that the isotopically enriched endmember sampled in the Eastern Volcanic Zone is depleted in the HSE, consistent with it being mafic in nature. The abundances of MgO in the lavas also roughly correlate with isotopic parameters, supporting the identity of the depleted endmember as ultramafic and the enriched endmember as mafic. New and previously published double-spike Pb isotope data show chiefly binary mixing with an additional component present in the vicinity of the volcano Öræfajökull. Icelandic 207Pb/204Pb and 208Pb/204Pb data plot below and above the majority of Mid-Atlantic Ridge basalt data, respectively, indicating that both depleted and enriched end-members in the plume have a lower U depletion age and a higher Th/U than ambient mantle. This is consistent with the enriched and depleted end-members within the Iceland plume being <2 Ga recycled oceanic crust and lithospheric mantle, respectively.

Wearable Patch Heart Rate Variability Is an Early Marker of Systemic Inflammation During Experimental Human Endotoxemia.

Early diagnosis and treatment can reduce the risk of organ failure and mortality in systemic inflammatory conditions. Heart rate variability (HRV) has potential for early identification of the onset of systemic inflammation, as it may detect changes in sympathetic nervous system activity resulting from the developing inflammatory response before clinical signs appear. With the use of new methodologies, we investigated the onset and kinetics of HRV changes as well as several inflammatory parameters and symptoms during experimental human endotoxemia, a model of systemic inflammation in humans in vivo. Healthy volunteers were intravenously administered LPS (n = 15) or placebo (n = 15). HRV was determined using a wireless wearable device, and parameters low to high frequency (LF:HF) ratio, root mean square of the successive differences (RMSSD), and standard deviation of normal-to-normal R-R intervals (SDNN)were calculated through 1-min-rolling 6-min windows. Plasma cytokine levels and flu-like symptoms and vital signs were serially assessed. The increase in LF:HF ratio, reflecting sympathetic predominance, was more pronounced in the LPS group compared to the placebo group, with the difference becoming statistically significant 65 min following LPS administration (1.63 [1.42-1.83] vs. 1.28 [1.11-1.44], P = 0.005). Significant between-group differences in RMSSD and SDNN were observed from 127 to 140 min post-LPS administration onwards, respectively. Plasma cytokine levels showed significant between-group differences staring 60 min post-LPS. For symptom score, heart rate, temperature, and diastolic blood pressure, significant differences compared with the placebo group were observed at 90, 118, 120, and 124 min post-LPS, respectively. In a controlled human model of systemic inflammation, elevations in the LF:HF ratio followed very shortly after elevations in plasma cytokine levels and preceded onset of flu-like symptoms and alterations in vital signs. HRV may represent a promising non-invasive tool for early detection of a developing systemic inflammatory response.

Effect of Hypoglycemia on Heart Rate Variability in People with Type 1 Diabetes and Impaired Awareness of Hypoglycemia.

Background:People with impaired awareness of hypoglycemia (IAH) are at elevated risk of severe, potentially hazardous, hypoglycemia and would benefit from a device alerting to hypoglycemia. Heart rate variability (HRV) changes with hypoglycemia due to sympathetic activity. Since IAH is associated with suppressed sympathetic activity, we investigated whether hypoglycemia elicits a measurable change in HRV in patients with T1D and IAH.Method:Eligible participants underwent a modified hyperinsulinemic euglycemic hypoglycemic clamp (glucose nadir, 43.1 ± 0.90 mg/dl), while HRV was measured by a VitalConnect HealthPatch. Measurements of HRV included Root Mean Square of the Successive Differences (RMSSD) and low to high frequency (LF:HF) ratio. Wilcoxon rank-sum test was used for testing within-subject HRV changes.Results:We included 12 participants (8 female, mean age 57 ± 12 years, mean HbA1c 57 ± 5 mmol/mol (7.4 ± 0.4%)). Symptoms increased from 4.0 (1.5-7.0) at euglycemia to 7.5 (5.0-11.0) during hypoglycemia (P = .003). In response to hypoglycemia, the LF:HF ratio and RMSSD increased when normalized for data obtained during euglycemia (both P < .01). The LF:HF ratio increased in 6 participants (50%) and declined in one other participant (8%). The RMSSD decreased in 3 (25%) and increased in 4 (33%) participants. In 2 patients, no change in HRV could be detected in response to hypoglycemia.Conclusions:This study reveals that hypoglycemia-induced changes in HRV are retained in the majority of people with T1D and IAH, and that these changes can be detected by a wearable device. Real-time HRV seems usable for detection of hypoglycemia in patients with IAH.

Variation in the analytical figure of merit for in situ Hf isotopic measurements by LA-MC-ICPMS in zircon standards at variable spatial resolutions.

Lu-Hf isotopic systematics is a powerful tool and gained importance as a geochemical tracer in geosciences. A multi-collector inductively coupled plasma mass spectrometer coupled with a laser ablation system has been used to perform zircon hafnium (Hf) isotopic analysis, and protocol is established for measurement of Hf isotopes. Toward this, two zircon standards, Z91500 and Plesovice, have been used for Hf isotopic measurements at four different spot sizes (50, 40, 25, and 20 μm). The isotopic data for ≥25 μm have an excellent agreement with published data, but for 20 μm, the results are erroneous and irrelevant to geological application. It has been observed that Hf beam intensity has a linear relation to the volume of the target (RM) ablated. 178 Hf/177 Hf ratio and ɛHf for both standards are comparable with the published recommended values. The present study indicates that 176 Lu/177 Hf ratio for Z91500 is more homogeneous than Plesovice zircon. The 176 Hf/177 Hf isotopic ratio for 50 and 25 μm shows an excellent agreement with the previously reported data. However, for 40-μm spot size, a slightly higher but negative offset of -123 and -105 ppm in 176 Hf/177 Hf ratio have been observed for Plesovice and 91500, respectively.

The effects of six-week slow, controlled breathing exercises on heart rate variability in physically active, healthy individuals

Background and Study Aim: Heart rate variability (HRV) provides information about sympathetic-parasympathetic balance. The effects of different types of physical exercises on HRV have been investigated so far. The purpose of the current study was to evaluate the chronic effects of six-week slow and controlled breathing exercise on HRV in physically active, healthy adults.&#x0D; Material and Methods: A total of 22 individuals (11 female, 11 male) participated in the study voluntarily. The experimental group (EG) attended to the breathing exercises for 15 minutes per day, three days a week for six weeks. Neither the EG nor the control group (CG) did join in any regular physical activity program during the study. Both groups participated in the HRV measurements before and after the six-week of process.&#x0D; Results: Only the EG showed statistically significant changes in some HRV parameters. The alterations observed in LF:HF ratio, HFnu, and LFnu parameters were to reflect the increase in parasympathetic activity. Although the changes in the other parameters of HRV such as SDNN, SDSD, RMSSD, TP, HF, LF, and VLF were also related to increased vagal activity, these alterations were not significant. However, no significant change was found in the CG.&#x0D; Conclusions: These results show that only the slow, controlled breathing exercises for six weeks could be used to improve parasympathetic activity in physically active individuals. A study could be designed where the duration is kept over 8 weeks, and the effects of physical exercises only, breathing exercises only, and physical + breathing exercises together on HRV are examined.

The effects of six-week slow, controlled breathing exercises on heart rate variability in physically active, healthy individuals

Background and Study Aim: Heart rate variability (HRV) provides information about sympathetic-parasympathetic balance. The effects of different types of physical exercises on HRV have been investigated so far. The purpose of the current study was to evaluate the chronic effects of six-week slow and controlled breathing exercise on HRV in physically active, healthy adults.&#x0D; Material and Methods: A total of 22 individuals (11 female, 11 male) participated in the study voluntarily. The experimental group (EG) attended to the breathing exercises for 15 minutes per day, three days a week for six weeks. Neither the EG nor the control group (CG) did join in any regular physical activity program during the study. Both groups participated in the HRV measurements before and after the six-week of process.&#x0D; Results: Only the EG showed statistically significant changes in some HRV parameters. The alterations observed in LF:HF ratio, HFnu, and LFnu parameters were to reflect the increase in parasympathetic activity. Although the changes in the other parameters of HRV such as SDNN, SDSD, RMSSD, TP, HF, LF, and VLF were also related to increased vagal activity, these alterations were not significant. However, no significant change was found in the CG.&#x0D; Conclusions: These results show that only the slow, controlled breathing exercises for six weeks could be used to improve parasympathetic activity in physically active individuals. A study could be designed where the duration is kept over 8 weeks, and the effects of physical exercises only, breathing exercises only, and physical + breathing exercises together on HRV are examined.

English

BACKGROUND Reduced heart rate variability (HRV) is associated with an increased risk of cardiovascular morbidity and mortality. The aim of the study was to determine whether reduced HRV is predictive of angiographic coronary artery disease (CAD) METHODS This study was done among 71 clinically stable subjects who underwent elective coronary angiography for diagnosis or pre-operative evaluation. High frequency (HF; 0.15 – 0.40 Hz), low frequency (LF; 0.04 – 0.15 Hz), LF / HF ratio, total power ≤ 0.4 Hz were used as the conventional indices of HRV. Analysis of variance (ANOVA) and chi square test was used to assess the statistical analysis. Statistical significance analysis was carried out with International Business Machines Statistical Package for the Social Sciences (IBM SPSS) version 22. RESULTS Out of 71 subjects, only 58 were available for final analysis. 20 subjects had normal coronary arteries, 19 had single vessel disease and remaining 19 had multi vessel disease. The HF power of HRV showed decreasing trend as the severity of angiographic stenosis increased. The median values of LF power for single vessel disease and multi vessel disease were 148 ms2 and 160 ms2 respectively. The group without coronary artery disease has a median of 215 ms2 for LF power. The median HF power was lower in single vessel disease group (133 ms2 ) compared to group with normal coronaries (139 ms2 ) and it was very low in multi vessel disease (81 ms2 ) group compared to group with normal coronaries. CONCLUSIONS A weak association of HF and LF power of HRV with degree of angiographic stenosis was observed. KEYWORDS Heart Rate Variability, Coronary Angiogram, Angiographic Stenosis

A Study of Cardiac Autonomic Functions in Patients with Chronic Stable Angina Undergoing Percutaneous Coronary Revascularization.

ObjectiveIn the present study, cardiac autonomic functions in CSA patients were evaluated before and after percutaneous coronary intervention (PCI) using heart rate variability (HRV).MethodsThirty patients with CSA were recruited from cardiology outpatient clinics of VMMC and Safdarjung hospital, New Delhi, India. For each patient HRV parameters (LF, HF, LF:HF ratio, SDNN, RMSSD, total power, and pNN50) were gathered before and after PCI. Data were compiled and analyzed using licensed statistical software: SPSS version 21.0.ResultsOut of 30 subjects, SDNN (61.47±22.27 vs. 32.24±16.50ms, p<0.0001), RMSSD (53.86±31.41 vs. 28.81±23.80ms, p=0.001) and pNN50 (46.24±34.36 vs. 5.20±6.63, p<0.0001) in post-PCI were significantly higher as compared to the pre-PCI values. There were significant increases in both LF (1193ms2±302.04ms2vs. 1054.60ms2±208 ms2, p<0.001) and HF (991.57±872.40ms2vs. 466.72ms2±257.93ms2, p<0.0001), also in total power (3548.37ms2±807.73ms2vs. 2428 ms2±867.07 ms2, p<0.0001) in post-PCI as compared to pre-PCI. The LF:HF ratio in pre-PCI was higher as compared to post-PCI (1.467±1.639 vs. 1.143±0.852, p=0.805), but the difference was not statistically significant.ConclusionIn this preliminary study, it is concluded that there is significant improvement in resting cardiovascular parameters, resting autonomic tone as measured by HRV which shows increase in both parasympathetic as well as sympathetic reactivity following revascularization by PCI in CSA patients. Hence, we also suggest that the use of noninvasive tests such as HRV should be done to stratify further risk of disease progression.

Нeart rate variability of children aged 8-11 with deprivation of auditory function

ntroduction.Currently, there are quite a number of publications on the peculiarities of heart rate in children with hearing impairments. However, such studies were conducted with individuals who had varying degrees of deafness and virtually did not examine children with congenital deafness.Children with congenital deafness are likely to have significant changes in cardiovascular system (CVS) indicators compared to their healthy peers. Purpose.The aim of the study was to elucidate the mechanisms of heart rate regulation in children with deprivation of auditory function during active orthostatic testing. Methods. The study involved 15 children: boys (7 individuals) and girls (8 individuals) aged 8-11 with congenital deafness and 17 almost healthy peers. Cardiorhythmograms were recorded with spectral characteristics of heart rate: (VLFms2, less than 0.05 Hz), low (LFms2, 0.05--0.4 Hz) frequencies; the ratio of LF/HF was considered.Results.The results of the study suggest that a group of childrenwith hearing deprivation in all indicators of spectral analysis of HRV had a much lower reactivity of the CVScompared to their healthy peers. The LF indicator did not change significantly, and therefore the sympathetic link of regulation did not play a significant role. However, the contribution of the parasympathetic system, which can be judged by HF, was significantly reduced in both groups. Thus, we can assume that the regulation of blood circulation was due to reduced activation of the parasympatheticlink with constant sympathetic. This feature is indicated by the indicator of vagosympathetic balance of the LF / HF ratio. Its changes reached quite significant values: 87.5% in deaf and 262.5% in healthy children. This indicates the leading role of the sympathetic system in the regulation of heart rhythm in children 8-11 years during orthostasis. However, the differences in the reactivity of the CVSof representatives of different groups indicated a less pronounced degree of activation of this link in the regulation of children with derivation of auditory function.The ratio of the length and width of the autocorrelation cloud (L / W) indicated a similar dependence. The dynamics of this indicator in the direction of increase may indicate a change in the intensity of the autonomic circuit regulation of cardiac activity. 202159In healthy subjects, these changes occurred with a greater degree of activation of central regulatory mechanisms than in children with hearing impairments.Because TP is an almost complete physiological analogue of SDNN, its decrease during orthostasis in children with hearing deprivation by 20.1% and 44.2% in healthy people indicates that the total effect of central regulation mechanisms decreases.Originality.Currently, there are virtuallyno data on reactive changes in the cardiovascular system of children with hearing impairments to postural gravitational loads, especially in relation to children with congenital deafness. This is important given that information about the reactions of thecardiovascular system of children with hearing impairments will allow you to adjust the exercise, choose the optimal motor mode and predict possible deviations or pathologies.Conclusion.Children with the deprivation of auditory function are characterized by more pronounced maladaptive responses of the cardiovascular system to orthostatic load than their healthypeers. Central regulatory mechanisms in deaf children have less pronounced activation compared to healthy children. At orthostatic test, in both groups of subjects, regulation of blood circulation is carried out mainly at the expense of a parasympathetic link of an autonomic nervous system.Keywords. deprivation of auditory function, heart rate variability, spectral analysis

Validity of the Polar V800 heart rate monitor for assessing cardiac autonomic control in individuals with spinal cord injury

Aim: Spinal cord injury (SCI) is associated with changes in cardiac autonomic control, that can be evaluated by heart rate variability (HRV), for which the electrocardiogram (ECG) is the gold standard. However, the use of ECG is limited to laboratory environments, and new tools are needed for this purpose and that can be applied in the routine monitoring of individuals with SCI. The present study aimed to investigate the validity of the Polar V800 heart rate monitor in assessing the cardiac autonomic control of individuals with SCI. Methods: Nineteen adult men with SCI (paraplegia n = 10; 44.5 ± 8.5 years and tetraplegia n = 9; 34.4 ± 7.5 years) participated in this cross-sectional study. The participants remained in the sitting position at rest for 10 min for the acquisition of the ECG and Polar V800 signals. The last 5-min window was used to count the beat-by-beat R-R interval series and then calculate the HRV indices (linear methods in the time and frequency domains). The study subgroups were compared, and the validity of the measurements generated with a heart rate monitor was determined using the intraclass correlation coefficient (ICC2,1) and Bland-Altman graphs. Results: Agreement analyses for the R-R intervals, SDNN, rMSSD, PNN50, SD1, LF, HF, and LF: HF ratio tended to show reliability ranging from acceptable to excellent (ICC = 0.579-0.990; P = 0.043-0.001) and acceptably narrow limits of agreement within both the group with tetraplegia and the group with paraplegia. Conclusion: The Polar V800 heart rate monitor is a valid instrument for assessing HRV in individuals with paraplegia and tetraplegia.

Seasonal and secular variations in selected indicators of the cardiovascular system among 7-11 years old children

The aim was to study seasonal variations in selected indicators of the cardiovascular system (CVS) in primary school students over 5 academic years and compare the findings with the results obtained in 2004-2007. Methods. Heart rate (HR) and its variability, blood pressure (BP) and its variability and cardiac performance were studied using spiroarteriocardiorhythmograph (SACR). Data were collected in late March - early April and late September - early October. The measurements were taken in in 2016-2019 (n=214, 701 measurements) and in 2004-2007 (n=317, 810 measurements). The analysis of the dynamics of semiannual changes ("delta" indicators, in% of the initial level) of CVS indicators of schoolchildren was carried out. As a comparison group, we used adult women (sample size -285 people), surveyed once in different seasons in 2002-2012. Results. Seasonal variability was revealed only for systolic blood pressure and LF / HF ratio reflecting the level of autonomic regulation of the cardiovascular system. In 2016-2019, in the sample of primary school students, an increase in systolic blood pressure over the school year (autumn - spring) and a decrease in LF / HF (in 2 nd - 5th grades ) was fixed. However, in 2004-2007 in children of the same age, seasonal changes had the opposite direction - a decrease in systolic blood pressure over the school year and an increase in LF / HF (in 1st - 5th grades), which corresponds to the seasonal variation of these indicators in adults. Conclusion. The obtained data showed a change in seasonal variability of the functional state of the CVS in primary school children. It has been suggested that such changes could be related to the computerization of education, but further research is warranted.

Rifting of the oceanic Azores Plateau with episodic volcanic activity

Extension of the Azores Plateau along the Terceira Rift exposes a lava sequence on the steep northern flank of the Hirondelle Basin. Unlike typical tholeiitic basalts of oceanic plateaus, the 1.2 km vertical submarine stratigraphic profile reveals two successive compositionally distinct basanitic to alkali basaltic eruptive units. The lower unit is volumetrically more extensive with ~ 1060 m of the crustal profile forming between ~ 2.02 and ~ 1.66 Ma, followed by a second unit erupting the uppermost ~ 30 m of lavas in ~ 100 kyrs. The age of ~ 1.56 Ma of the youngest in-situ sample at the top of the profile implies that the 35 km-wide Hirondelle Basin opened after this time along normal faults. This rifting phase was followed by alkaline volcanism at D. João de Castro seamount in the basin center indicating episodic volcanic activity along the Terceira Rift. The mantle source compositions of the two lava units change towards less radiogenic Nd, Hf, and Pb isotope ratios. A change to less SiO2-undersaturated magmas may indicate increasing degrees of partial melting beneath D. João de Castro seamount, possibly caused by lithospheric thinning within the past 1.5 million years. Our results suggest that rifting of oceanic lithosphere alternates between magmatically and tectonically dominated phases.

Disturbances of Autonomic Regulation of Cardiovascular System at Different Working Regimes with Night Shifts

Aim To study temporal and spectral characteristics of heart rhythm variability (HRV) in night shift workers.Materials and methods Along with traditional risk factors, conditions of labor contribute to development of cardiovascular morbidity, including night shift work, which can be associated with disorders of the autonomic regulation detected by analysis of HRV. This study included 100 healthy men. 74 of them were engaged in shift work, including 53 men with rotating shift work, 21 men with fixed night shifts, and 26 men with day-time work. HRV was analyzed by data of 5-min electrocardiogram recording (background recording and orthostatic test).Results Night-shift workers had decreases in total power of regulation (ТР, SDNN) and in the parasympathetic branch (HF, pNN50). Rotating night-shift workers displayed significant decreases in SDNN and pNN50 and pronounced changes in the VLF / LF / HF ratio in the orthostatic test.Conclusion In work with night shifts, the type of autonomic regulation differs from the "standard" functioning of the autonomic nervous system (ANS). This study showed different effects of night work regimens on HRV indexes. With the rotating shift work, the ANS dysregulation was more profound and was evident by a significant decrease in the ANS total tone and parasympathetic activity (SDNN, pNN50) compared to night shifts with fixed working hours. The excessive weakening of the parasympathetic component in the passive orthostatic test can be considered as an early marker for ANS maladaptation.

Measurement of L subshell fluorescence yield ratios of some high Z elements by selective excitation method

The L1, L2 and L3 subshells of Hf, Ta and Re atoms have been excited selectively by using microprobe XRF beam line, Indus‐2, RRCAT, India. The consequent characteristic L X‐ray photons, emitted from the targets due to creations of vacancies in L subshells, are measured using silicon drift detector (X‐123) spectrometer. As the energy of synchrotron radiation increases, the contribution of characteristic L X‐ray intensity increases. The advantage of the increase in the intensity of the characteristic L X‐ray photons with an increase in the energy of synchrotron radiation has been used to determine the L subshell fluorescence yield ratios of Hf, Ta and Re atoms by adopting the selective excitation method. The measured ratios of L subshell fluorescence yield have been compared with theoretical and other experimental values.

Short-term aerobic training improves heart rate variability in men living with HIV: a pre-post pilot study

Background Heart rate variability (HRV) a feasible predictor of prognosis in cardiovascular outcomes shown to be reduced in people living with HIV (PLWH). Objective This study sought to understand the effects of short-term aerobic training (AT) on the resting HRV and endothelial function in this population. Methods PLWH performed 24 sessions of AT protocol. The protocol consists of 40 min of treadmill (60 to 80% of the VO2max), 3 times per week, for 8 weeks. HRV (standard deviation of all normal RR intervals - SDNN; root mean square of the successive differences - rMSSD; low frequency - LF; high frequency - HF; LF:HF ratio) and endothelial function parameters were evaluated by EndoPAT system pre and post intervention. Results 7 men, the median age of the sample was 49 years (range, 38–68 years), completed the protocol. AT improved resting HRV parameters: SDNN (p = 0.02, power analysis (PA) 0.54), rMSSD (p = 0.02, PA = 0.99), LF (p = 0.02, PA = 0.85). HF, LF:HF ratio and endothelial function parameters showed no changes. Conclusions The results suggest the short-term AT may improve HRV in men living with HIV.

Immediate Effects of Yoga Based Relaxation Technique Yoga Nidra on Heart Rate Variability in Young and Healthy Volunteers

Introduction: Cardiovascular autonomic functions are affected by the negative influences of stress which bring about alterations in heart rate variability (HRV). Yoga based relaxation techniques like Yoga Nidra have been found to relieve stress as shown by improved HRV. This study was conducted to assess the immediate effects of a yoga based guided relaxation technique, Yoga Nidra on HRV parameters in young and healthy volunteers.&#x0D; Methods: This was an interventional study conducted in the Department of Clinical Physiology, Institute of Medicine, Maharajgunj. Fifty two male medical students were divided into supine rest group (n=26) and Yoga Nidra group (n=26). HRV indices were recorded before and after supine rest and Yoga Nidra. Intra-group and inter-group comparisons of the HRV parameters were done before and after the interventions.&#x0D; Results: In comparison to the supine rest, Yoga Nidra produced significant increase in values of HF (1460.72 Vs 3272.99; p=0.03) and HFnu (50.32 Vs 62.68; p=0.004); and significant reduction in the values of LFnu (49.68 Vs 37.32; p=0.004) and LF:HF ratio (0.99 Vs 0.59; p=0.004), which suggested that the parasympathetic modulating response of Yoga Nidra was better than that of supine rest.&#x0D; Conclusion: Yoga Nidra, a yoga based relaxation technique brings better relaxation response than supine rest as indicated by the significantly improved HRV indices.

A precise geochemical volcano-stratigraphy of the Deccan traps

This geochemical study is based on 69 volcanic rocks representing the entire volcano-stratigraphy of the 12 lava formations of the Deccan Traps (DT) of the Indian peninsula. The DT constitutes one of the largest continental flood basalt province (CFB) in the world. More than 90% of the lavas of this province are considered to have erupted in less than one million years by plume volcanism, coinciding with the Cretaceous-Paleogene (K-Pg) boundary, leading to the speculation that this volcanism had a major role in the end-Cretaceous mass extinction. The current study was undertaken to fully geochemically characterize the DT plume with respect to major-trace element composition as well as their correlated Sr-Nd-Pb and Hf isotope geochemistry of each lava formation in step-by-step sampling the entire Deccan vertical stratigraphy of over 60 samples mostly on the Western Ghat Escarpment as collected by Beane (1988).The upper lava formations from Poladpur to Panhala-Desur, the Wai subgroup, are sharply distinguishable geochemically by all the geochemical parameters from the lower lava formations of the Lonavala and Kalsubai subgroups. This distinction is remarkable as they are on samples in a continuous supposedly vertical sequence in space and time. The Wai subgroup shows restricted range in FeO/MgO ratios at a given MgO wt% but indicating a more Fe-rich mantle source than many other CFB (average Mg# 46.7 as opposed to the 53.3 Mg# for the lower subgroups) province; the lower subgroups show a widely variable FeO/MgO ratios, interpreted as results of partial melting of subducted eclogitic slab. This interpretation is supported by the trace elements including the rare earths, and the isotopic ratios of Nd, Sr, Pb and Hf that were all measured in the same lava samples. Our high precision Pb isotopic measurements reveal the gist of the Deccan plume characteristics as Pb content in the mantle is low in contrast with their higher abundance in the continental crust. The Wai subgroup demonstrates a relatively consistent initial 206Pb/204Pb ratios as opposed to their heterogeneous compositions in the lower formations of Lonavala and Kalsubai. In addition, the Pb isotopes in a 206Pb/204Pb vs 207Pb/204Pb plot define an age of 2604 ± 140 Ma that we interpret as the “provenance” age of the subducted slab that sourced the lower formation lavas. Interestingly, this “errorchron” is also consistent with the “Dupal anomaly” concept developed on the sub Indian Oceanic mantle derived basalts.The combined multiple isotopic volcano-stratigraphy shows the geochemical contrast more dramatically than any other previous study on the Deccan. This high precision multiple isotopic study of the Deccan is consistent with recent U-Pb and Ar-Ar geochronologic studies on the rapid eruption of the Deccan, mostly the plume head, interpreted here constituting the upper lava formations of the Wai subgroup as without much interaction with the continental crust.

Assessment of the association of heart rate variability and baroreflex sensitivity with depressive symptoms and stress experienced by women in pregnancy

BackgroundPregnancy is a unique physiological state with systemic changes including cardiovascular, autonomic, hemodynamic and psychological. Increase in incidence of stress and depression in antenatal period has been reported. Autonomic changes in pregnancy and its dysfunction in depression are well documented. However, there is lack of evidence associating cardiovascular autonomic dysfunction to stress and depressed mood in pregnant women. MethodsIn this correlation study, we assessed cardiovascular autonomic functions of 172 pregnant women using heart rate variability (HRV) and baroreflex sensitivity (BRS). The Edinburg postnatal depression scale (EPDS) was used to evaluate depressive symptoms and perceived stress scale (PSS) was used to assess stress. The HRV and BRS parameters were correlated with EPDS and PSS. Multiple regression analysis was performed for EPDS and PSS individually to study their association with cardiac autonomic functions(CAF). ResultsHRV and BRS were well correlated to EPDS and PSS scores. The depression and stress were found to be significantly associated to autonomic dysfunctions as increased sympathetic and decreased parasympathetic activity. Among various CAF parameters, LF:HF ratio and BRS were found to be significantly associated with depression and stress among these women. ConclusionLF:HF ratio and BRS may be associated with depression during antenatal period. The depression in antenatal period may add on to cardiovascular risk in expecting mothers.

Active women demonstrate acute autonomic and hemodynamic shifts following exercise in heat and humidity: A pilot study

ABSTRACT The purpose of this study was to assess autonomic and hemodynamic recovery in women who performed moderate-intensity exercise in heat. Seven women (31.7 ± 7.6 years, 67.5 ± 4.4 kg, 25.7 ± 5.6% Fat, 43.9 ± 5.1 mL/kg/min) completed two identical bouts of graded treadmill walking (~60% VO2peak). One bout was hot (37.5 ± 1.4°C, 46.5 ± 4.6% relative humidity (RH)), and the other was moderate (20.7 ± 1.1°C, 29.9 ± 4.1% RH). For 24 h before and one h after each bout, participants had heart rate variability monitored. After each exercise bout HR and BP were measured during 30 min of supine recovery and 10 min of orthostatic challenge. HF power and RMSSD were lower and LF power and LF:HF ratio greater following exercise in the heat and remained different from the moderate condition for 30 min (p < 0.05). During supine recovery, heat exposure led to higher HR (p = 0.002) and lower DBP (p = 0.016). SBP (p = 0.037) and DBP (p = 0.008) were both lower after 10 min of supine recovery following hot exercise than after moderate temperature. Average response did not reveal orthostatic hypotension despite heat causing a higher HR (p = 0.011) and lower SBP (p = 0.026) after 10 min of orthostatic exposure. Trained women exhibit an autonomic shift toward sympathetic dominance for at least 30 min after exercise in heat. Women who exercise in heat should be wary of an exacerbated HR response after exercise and low recovery blood pressures.