Physiological effects of Shinrin-yoku (taking in the atmosphere of the forest)--using salivary cortisol and cerebral activity as indicators

The purpose of this study is to examine the physiological effects of Shinrin-yoku (taking in the atmosphere of the forest). The subjects were 12 male students (22.8+/-1.4 yr). On the first day of the experiments, one group of 6 subjects was sent to a forest area, and the other group of 6 subjects was sent to a city area. On the second day, each group was sent to the opposite area for a cross check. In the forenoon, the subjects were asked to walk around their given area for 20 minutes. In the afternoon, they were asked to sit on chairs and watch the landscapes of their given area for 20 minutes. Cerebral activity in the prefrontal area and salivary cortisol were measured as physiological indices in the morning at the place of accommodation, before and after walking in the forest or city areas during the forenoon, and before and after watching the landscapes in the afternoon in the forest and city areas, and in the evening at the place of accommodation. The results indicated that cerebral activity in the prefrontal area of the forest area group was significantly lower than that of the group in the city area after walking; the concentration of salivary cortisol in the forest area group was significantly lower than that of the group in the city area before and after watching each landscape. The results of the physiological measurements show that Shinrin-yoku can effectively relax both people's body and spirit.     

Differences in Salivary Alpha-Amylase and Cortisol Responsiveness following Exposure to Electrical Stimulation versus the Trier Social Stress Tests

Background

Cortisol is an essential hormone in the regulation of the stress response along the HPA axis, and salivary cortisol has been used as a measure of free circulating cortisol levels. Recently, salivary alpha-amylase (sAA) has also emerged as a novel biomarker for psychosocial stress responsiveness within the sympathetic adrenomedullary (SAM) system.

Principal Findings

We measured sAA and salivary cortisol in healthy volunteers after exposure to the Trier Social Stress Test (TSST) and electric stimulation stress. One hundred forty-nine healthy volunteers participated in this study. All subjects were exposed to both the TSST and electric stimulation stress on separate days. We measured sAA and salivary cortisol levels three times immediately before, immediately after, and 20 min after the stress challenge. The State (STAI-S) and Trait (STAI-T) versions of the Spielberger Anxiety Inventory test and the Profile of Mood State (POMS) tests were administered to participants before the electrical stimulation and TSST protocols. We also measured HF, LF and LF/HF Heart Rate Variability ratio immediately after electrical stimulation and TSST exposure. Following TSST exposure or electrical stimulation, sAA levels displayed a rapid increase and recovery, returning to baseline levels 20 min after the stress challenge. Salivary cortisol responses showed a delayed increase, which remained significantly elevated from baseline levels 20 min after the stress challenge. Analyses revealed no differences between men and women with regard to their sAA response to the challenges (TSST or electric stimulations), while we found significantly higher salivary cortisol responses to the TSST in females. We also found that younger subjects tended to display higher sAA activity. Salivary cortisol levels were significantly correlated with the strength of the applied electrical stimulation.

Conclusions

These preliminary results suggest that the HPA axis (but not the SAM system) may show differential response patterns to distinct kinds of stressors.     

Heart rate variability and body temperature during the sleep onset period

Heart rate variability (HRV) and body temperature during the sleep onset period was examined. The core body temperature and electrocardiogram were recorded continuously beginning 1 h before lights out (LO) until the end of the first rapid eye movement sleep (REM) in 14 young healthy subjects. HRV was calculated by the MemCalc method. The time course changes in body temperature and HRV was analyzed before and after sleep onset, and during the following eight consecutive phases: the 60 min before LO, the 30 min before LO, LO, first stage 2 (sleep onset), first slow wave sleep (SWS), stage 2 just before REM, start of REM, and end of REM. A clear decline was observed in the ratio of the low frequency (LF) to high frequency (HF) component of HRV (LF/HF), normalized LF (LF/(LF + HF)), and body temperature prior to sleep onset both in the time course of the sleep onset period and in the consecutive phases. The HF increased prior to sleep onset in the consecutive phases, while no clear increase was observed in the time course of sleep onset period. Changes in LF/(LF + HF) and LF/HF preceded SWS and REM. These results suggest the existence of a strong coupling between the cardiac autonomic nervous system and body temperature at the sleep onset period that may not be circadian effects. Furthermore, LF/(LF + HF) and LF/HF may possibly anticipate sleep and the onset of each sleep stage.

     

A circadian rhythm in heart rate variability contributes to the increased cardiac sympathovagal response to awakening in the morning

Morning hours are associated with a heightened risk of adverse cardiovascular events. Recent evidence suggests that the sleep-wake cycle and endogenous circadian system modulate cardiac function in humans and may contribute to these epidemiological findings. The aim of the present study was to investigate the interaction between circadian and sleep-wake-dependent processes on heart rate variability (HRV). Fifteen diurnally active healthy young adults underwent a 72-h ultradian sleep-wake cycle (USW) procedure (alternating 60-min wake episodes in dim light and 60-min nap opportunities in total darkness) in time isolation. The present study revealed a significant main effect of sleep-wake-dependent and circadian processes on cardiac rhythmicity, as well as a significant interaction between these processes. Turning the lights off was associated with a rapid increase in mean RR interval and cardiac parasympathetic modulation (high-frequency [HF] power), whereas low-frequency (LF) power and sympathovagal balance (LF:HF ratio) were reduced (p?≤?.001). A significant circadian rhythm in mean RR interval and HRV components was observed throughout the wake and nap episodes (p?≤?.001). Sleep-to-wake transitions occurring in the morning were associated with maximal shifts towards sympathetic autonomic activation as compared to those occurring during the rest of the day. Namely, peak LF:HF ratio was observed in the morning, coincidental with peak salivary cortisol levels. These results contribute to our understanding of the observed increase in cardiovascular vulnerability after awakening in the morning.     

Heart rate variability after radiofrequency ablation of epicardial ganglionated plexuses on the ovine left atrium

Background

Ganglionated plexuses (GP) are terminal parts of cardiac autonomous nervous system (ANS). Radiofrequency ablation (RFA) for atrial fibrillation (AF) possibly affects GP. Changes in heart rate variability (HRV) after RFA can reflect ANS modulation.

Methods

Epicardial RFA of GP on the left atrium (LA) was performed under the general anesthesia in 15 mature Romanov sheep. HRV was used to assess the alterations in autonomic regulation of the heart. A 24???hour ECG monitoring was performed before the ablation, 2 days after it and at each of the 12 following months. Ablation sites were evaluated histologically.

Results

There was an instant change in HRV parameters after the ablation. A standard deviation of all intervals between normal QRS (SDNN), a square root of the mean of the squared differences between successive normal QRS intervals (RMSSD) along with HRV triangular index (TI), low frequency (LF) power and high frequency (HF) power decreased, while LF/HF ratio increased. Both the SDNN, LF power and the HF power changes persisted throughout the 12???month follow???up. Significant decrease in RMSSD persisted only for 3 months, HRV TI for 6 months and increase in LF/HF ratio for 7 months of the follow???up. Afterwards these three parameters were not different from the preprocedural values.

Conclusions

Epicardial RFA of GP’s on the ovine left atrium has lasting effect on the main HRV parameters (SDNN, HF power and LF power). The normalization of RMSSD, HRV TI and LF/HF suggests that HRV after epicardial RFA of GPs on the left atrium might restore over time.

     

The influence of hydration status on heart rate variability after exercise heat stress

While exercise heat stress and hydration status are known to independently influence heart rate variability (HRV), the combined effect of these physiological stressors is unknown. Thus, heat-acclimated subjects (n=5) performed exercise heat trials (40 °C, 20% relative humidity) in the euhydrated and hypohydrated state (3.9±0.7% body weight loss). During each trial, cardiac cycle R–R interval data were collected for 45 min at rest (pre-) and after (post-) completing 90 min of cycle ergometer exercise. Pre- and post-exercise RRI data were analyzed by Fast Fourier Power Spectral analysis to determine the high-frequency (HF), low-frequency (LF), very low-frequency (VLF), and total power (TP) components of HRV. Overall HRV was decreased by both hypohydration and exercise heat stress. Hypohydration reduced TP, LF, VLF, and LF:HF ratio $(P<0.05)$ while HF was significantly higher. The change in both LF and HF power (pre- vs. post-exercise) were blunted during hypohydration compared to euhydration. These data suggest that dehydration alone positively influences the parasympathetic (HF) control of HRV, but the reduction in overall HRV and the blunted oscillations in LF and HF power following exercise heat stress support an overall deleterious effect of dehydration on autonomic cardiac stability.     

The Effect of a Single Session of Short Duration Biofeedback-Induced Deep Breathing on Measures of Heart Rate Variability During Laboratory-Induced Cognitive Stress: A Pilot Study

This study examines the acute effect of heart rate variability (HRV) biofeedback on HRV measures during and immediately after biofeedback and during the following laboratory-induced stress. Eighteen healthy males exposed to work-related stress were randomised into an HRV biofeedback group (BIO) or a comparative group (COM). Subjects completed a modified Stroop task before (Stroop 1) and after (Stroop 2) the intervention. Both groups had similar physiological responses to stress in Stroop 1. In Stroop 2, the COM group responded similarly to the way they did to Stroop 1: respiratory frequency (RF) and heart rate (HR) increased, RMSSD and high frequency (HF) power decreased or had a tendency to decrease, while low frequency (LF) power showed no change. The BIO group responded differently in Stroop 2: while RF increased and LF power decreased, HR, RMSSD and HF power showed no change. In the BIO group, RMSSD was higher in Stroop 2 compared to Stroop 1. In conclusion, HRV biofeedback induced a short term carry-over effect during both the following rest period and laboratory-induced stress suggesting maintained HF vagal modulation in the BIO group after the intervention, and maintained LF vagal modulation in the COM group.     

Association of salivary steroid hormones and their ratios with time-domain heart rate variability indices in healthy individuals

BackgroundStress system consists of the hypothalamicpituitary-adrenal (HPA) axis and the locus caeruleus/norepinephrine-autonomic nervous system (ANS). Traditionally, HPA axis activity is evaluated by measuring its end-product cortisol, while the activity of ANS is assessed using heart rate variability (HRV) indices. Alterations in cortisol levels and HRV measures during laboratory-based stress tasks were extensively studied in previous research. However, scarce data exist on the associations of HRV measures with the levels of other adrenal steroid hormones under baseline conditions. Thus, we aimed to evaluate the activity of the HPA axis by measuring salivary cortisol, cortisone, dehydroepiandrosterone (DHEA) levels, and their ratios and to examine its association with HRV measures in a sample of healthy young and middle-aged adults.MethodsFor each participant (n=40), three data collection sessions taking place at the same time of the day were scheduled within five working days. Participants completed a self-reported questionnaire on sociodemographic and lifestyle characteristics, filled out t h e Perceived Stress Scale and State-Trait Anxiety Inventory. Also, saliva samples were collected, and physiological measures, including resting HR and HRV, were recorded during three data collection sessions.ResultsStatistically significant associations between diminished parasympathetic vagal tone evaluated by time domain HRV measures and higher salivary cortisol, lower DHEA levels, as well as decreased DHEA to cortisol ratio, were found. Also, physiological stress indicators (i.e., HRV) showed greater intraindividual stability compared with biochemical biomarkers (i.e., salivary steroid hormones) within five days.ConclusionsOur findings suggest that both cortisol and DHEA mediate the link between two stress-sensitive homeostatic systems.     

Pre-service Teachers and Stress During Microteaching: An Experimental Investigation of the Effectiveness of Relaxation Training with Biofeedback on Psychological and Physiological Indices of Stress

Pre-service teacher stress is an understudied research area, with the majority of research focusing on subjective reports of stress. The present study sought to examine the influence of stress-reduction techniques on both subjective and objective indicators of stress during microteaching in preservice teachers. A sample of 44 preservice teachers were randomly assigned to one of three intervention groups; biofeedback, relaxation, or control. Participants in the biofeedback group received relaxation-assisted biofeedback training designed to teach participants the physiological signs of the stress response using HeartMath monitor, along with the HeartMath Quick Coherence® technique. Those in the relaxation group were given training in the HeartMath Quick Coherence relaxation technique, with no biofeedback training. Finally, those in the control group did not receive any relaxation or biofeedback training. Using a repeated-measures design, both psychological and physiological indices of stress were measured before and after students engaged in microteaching approaches. Examination of the psychological ratings identified that feelings of calm increased across time; this showed that participants were more comfortable with the microteaching situation with repeated practice. However, none of the physiological interventions were effective in reducing stress. The present study highlights practice as a useful strategy to reduce stress in microteaching situations and points to the importance of employing evidence-based interventions when attempting to reduce stress.     

先天性心脏病患儿介入封堵术治疗前后CRP、NT-proBNP、心率变异性的变化及与术后心功能的关系研究

摘要 目的：探讨先天性心脏病（CHD）患儿介入封堵术治疗前后C-反应蛋白（CRP）、N末端B型利钠肽原（NT-proBNP）、心率变异性（HRV）的变化及与术后心功能的关系。方法：选择2020年10月至2021年6月在本院行介入封堵术治疗的95例CHD患儿为研究对象,采用化学发光法检测血清CRP水平,采用电化学发光免疫技术检测血清NT-proBNP水平,采用24 h动态心电图及12导联同步心电图分析HRV指标,观察手术前后患儿的血清CRP、NT-proBNP水平及HRV指标变化,比较术后不同NYHA心功能分级患儿的血清CRP、NT-proBNP水平和HRV指标,分析患儿术前血清CRP水平、血清NT-proBNP水平、HRV指标与术后NYHA心功能分级的相关性。结果：介入封堵术后患儿血清CRP、NT-proBNP、LF/HF水平逐渐降低,术后3 d、术后1个月时均低于术前,术后1个月时均低于术后3 d时（P<0.025）;而TP、HF、LF、R-R、PNN50%、ASDNN、SDANN、SDNN、rMSSD水平逐渐升高,术后3 d、术后1个月时均高于术前,术后1个月时均高于术后3 d 时（P<0.025）。患儿术后3 d的血清CRP、NT-proBNP水平及LF/HF水平随着NYHA心功能分级的升高而升高,TP、HF、LF、R-R、PNN50%、ASDNN、SDANN、SDNN、rMSSD水平随着NYHA心功能分级的升高而降低（多有P＜0.05）。患儿术后3 d的NYHA心功能分级与治疗前血清CRP、NT-proBNP及LF/HF水平呈负相关,与TP、HF、LF、R-R、PNN50%、ASDNN、SDANN、SDNN、rMSSD水平呈正相关（P＜0.05）。结论：CHD患儿经介入封堵术治疗后,血清CRP、NT-proBNP及HRV指标变化明显,与术后NYHA心功能分级显著相关,血清CRP、NT-proBNP及HRV指标有望成为评估CHD患儿介入封堵术后预后的较敏感性指标。     

Differential Patterns and Determinants of Cardiac Autonomic Nerve Dysfunction during Endotoxemia and Oral Fat Load in Humans

The autonomic nervous system (ANS) plays an important role in regulating the metabolic homeostasis and controlling immune function. ANS alterations can be detected by reduced heart rate variability (HRV) in conditions like diabetes and sepsis. We determined the effects of experimental conditions mimicking inflammation and hyperlipidemia on HRV and heart rate (HR) in relation to the immune, metabolic, and hormonal responses resulting from these interventions. Sixteen lean healthy subjects received intravenous (i.v.) low-dose endotoxin (lipopolysaccharide [LPS]), i.v. fat, oral fat, and i.v. glycerol (control) for 6 hours, during which immune, metabolic, hormonal, and five HRV parameters (pNN50, RMSSD, low-frequency (LF) and high-frequency (HF) power, and LF/HF ratio) were monitored and energy metabolism and insulin sensitivity (M-value) were assessed. LPS infusion induced an increase (AUC) in HR and LF/HF ratio and decline in pNN50 and RMSSD, while oral fat resulted in elevated HR and a transient (hours 1-2) decrease in pNN50, RMSSD, and HF power. During LPS infusion, ΔIL-1ra levels and ΔIL-1ra and ΔIL-1ß gene expression correlated positively with ΔLF/HF ratio and inversely with ΔRMSSD. During oral fat intake, ΔGLP-1 tended to correlate positively with ΔHR and inversely with ΔpNN50 and ΔRMSSD. Following LPS infusion, lipid oxidation correlated positively with HR and inversely with pNN50 and RMSSD, whereas HRV was not related to M-value. In conclusion, suppression of vagal tone and sympathetic predominance during endotoxemia are linked to anti-inflammatory processes and lipid oxidation but not to insulin resistance, while weaker HRV changes in relation to the GLP-1 response are noted during oral fat load.

Trial Registration

ClinicalTrials.gov NCT01054989     

Interaction with indoor plants may reduce psychological and physiological stress by suppressing autonomic nervous system activity in young adults: a randomized crossover study

Background

Developments in information technology cause a great deal of stress to modern people, and controlling this stress now becomes an important issue. The aim of this study was to examine psychological and physiological benefits of interaction with indoor plants.

Methods

The study subjects were 24 young male adults at the age of 24.9 ± 2.1 (mean ± SD). The crossover experimental design was used to compare the differences in physiological responses to a computer task and a plant-related task. Subjects were randomly distributed into two groups. The first group (12 subjects) carried out transplanting of an indoor plant, whereas the second group (12 subjects) worked on a computer task. Then, each subject switched activities. The psychological evaluation was carried out using the semantic differential method (SDM) and physiological evaluation using heart rate variability (low-frequency (LF) and high-frequency (HF) components) and blood pressure.

Results

Analysis of the SDM data showed that the feelings during the transplanting task were different from that during the computer task: the subjects felt more comfortable, soothed, and natural after the transplanting task than after the computer task. The mean value of total log[LF/(LF + HF)] (sympathetic activity) increased over time during the computer task but decreased at the end of the transplanting task, and the differences were significant. Furthermore, diastolic blood pressure was significantly lower after the transplanting task.

Conclusions

Our results suggest that active interaction with indoor plants can reduce physiological and psychological stress compared with mental work. This is accomplished through suppression of sympathetic nervous system activity and diastolic blood pressure and promotion of comfortable, soothed, and natural feelings.     

Seasonal variation in heart rate variability in asthmatic children

Asthma is a "seasonal disease" with symptoms either aggravated by environmental changes during specific seasons or prevalent at certain times of the year for other reasons. We examined whether the heart rate variability (HRV) of asthmatic children changes by season. The HRV during a portion of one night (00:00-04:00) and day (12:00-16:00) and the entire 24h period (00:00-24:00) during each of the four seasons was analyzed. The data of 95 children with asthma and 106 healthy children, as controls, were assessed. In children with asthma during the 24h period, seasonal variation in the low-frequency (LF) band (0.04-0.15 Hz) and the high-frequency (HF) band (0.15-0.4 Hz) were detected (HF: F=6.81, p=.0003; LF: F=4.18, p= .008). The HF value in the summer was significantly higher than in autumn and spring (Scheffe test: autumn vs. summer, s = 4.46, p < .001: spring vs. summer, s = 2.86, p < .05), while the LF value in autumn was significantly lower than in summer (s = 3.42, p < .01). In the control group, no seasonal variation in HF, LF, or LF/HF was detected. The findings infer the HRV, a surrogate measure of autonomic nervous system function, of asthmatic children is more susceptible to seasonal changes brought about by either endogenous annual rhythms or environmental weather phenomena.     

Link between Peripheral Artery Disease and Heart Rate Variability in Hemodialysis Patients

Peripheral artery disease (PAD) and low heart rate variability (HRV) are highly prevalent in hemodialysis patients, and both are associated with increased cardiovascular morbidity and mortality. This study aims to examine the suggested relationship between PAD and HRV, and the relationship of parameters before and after hemodialysis. This study enrolled 161 maintenance hemodialysis patients. PAD was defined as ABI < 0.9 in either leg. HRV was performed to assess changes before and after hemodialysis. The change in HRV (△HRV) was defined as post-hemodialysis HRV minus pre-hemodialysis HRV. Patients’ clinical parameters were collected from the dialysis records. All HRV parameters except high frequency (HF) % were lower in patients with PAD than patients without PAD, though not achieving significant level. In patients without PAD, HF (P = 0.013), low frequency (LF) % (P = 0.028) and LF/HF (P = 0.034) were significantly elevated after hemodialysis, whereas no significant HRV parameters change was noted in patients with PAD. Serum intact parathyroid hormone was independently associated with △HF (β = -0.970, P = 0.032) and △LF% (β = -12.609, P = 0.049). Uric acid level (β = -0.154, P = 0.027) was negatively associated with △LF/HF in patients without PAD. Our results demonstrated that some of the HRV parameters were significantly increased after hemodialysis in patients without PAD, but not in patients with PAD, reflecting a state of impaired sympatho-vagal equilibrium. Severity of secondary hyperparathyroidism and hyperuricemia contributed to lesser HRV parameters increase after hemodialysis in patients without PAD.     

Cardiovascular reactivity to mental stress: relationship with menstrual cycle and gender

The purpose of the present study was to determine the fluctuation in cardiovascular reactivity to mental stress during the menstrual cycle by comparing heart rate variability (HRV), and other physiological and psychological data in females with those in males. Cardiovascular reactivity to two mental tasks was measured in 14 females during the follicular and luteal phase of menstruation over two menstrual cycles. The same tasks were subsequently given to a matched pair of males (N=14), at the same intervals as their corresponding females. Heart rate, blood pressure and HRV were used as indices of cardiovascular reactivity. Subjective mental workload was measured at the end of each task. Power spectral analysis of HRV showed that the high frequency (HF) component in HRV decreased more during the luteal phase than the follicular phase. The low frequency (LF) component in HRV and the LF/HF ratio in the luteal phase were significantly higher than that in the follicular phase. The LF component and the LF/HF ratio were significantly lower in females than in males; conversely, the HF component was significantly higher in females than in males. Neither significant effects of menstrual cycle, gender and mental stress nor any significant interactions were found for mental workload. These findings indicate that sympathetic nervous activity in the luteal phase is significantly greater than in the follicular phase whereas parasympathetic nervous activity is predominant in the follicular phase. The results also suggest that predominance of sympathetic nervous activity in males compared with a dominant parasympathetic nervous activity in females.     

The effect of wearing sanitary napkins of different thicknesses on physiological and psychological responses in Muslim females

Background

Menstruation is associated with significant unpleasantness, and wearing a sanitary napkin (SN) during menses causes discomfort. In addition, many Muslim women use a thick type of SN during menses due to the religious requirement that even disposable SNs be washed before disposal. Therefore, the objective of this study was to measure the physiological and psychological responses to wearing SNs of different thicknesses during menstruation and non-menstruation phases at rest and during physical activity/exercise among Muslim women.

Methods

Eighteen Muslim females were randomly assigned to wear an ultra slim type (US, thin) or a maxi type (MT, thick) SN on two different occasions (i.e., during non-menses and menses). Each subject tested both types of SN. Upon arriving at the laboratory, each subject was equipped with an ambulatory electrocardiograph and rested in a seated position for 10 min. She was then given either an US or MT SN, put it in place, and rested in a seated position for 10 min. Each subject then walked at 3 km/h for 10 min, sat resting for 10 min, and then walked at 5 km/h for another 10 min. At the end of each 10-min stage, subjects marked their feelings of discomfort on the visual analog scale (VAS). Perceived exertion during exercise was evaluated using the Borg scale. Heart rate and low frequency-to-high frequency ratio (LF/HF) of heart rate variability were continuously recorded during rest and exercise.

Results

During both the non-menses and menses trials, VAS and LF/HF were significantly lower in subjects using the US SN compared to the MT SN. These results indicate that when wearing the US SN, subjects were more comfortable and did not increase sympathetic activities. Meanwhile, perceived exertion during exercise had no significant difference between US and MT although the means of the scores for US tended to be lower than those of MT.

Conclusions

The results of this study (VAS and LF/HF) indicate that wearing an US SN induces less physiological and psychological stress compared to wearing a MT SN. Thus, use of the former will empower women to live their lives with vitality during menses.     

Preeclamptic pregnancy is associated with increased sympathetic and decreased parasympathetic control of HR

Previous work from our laboratory using heart rate variability (HRV) has demonstrated that women before menopause have a more dominant parasympathetic and less effective sympathetic regulations of heart rate compared with men. Because it is still not clear whether normal or preeclamptic pregnancy coincides with alternations in the autonomic functions, we evaluated the changes of HRV in 17 nonpregnant, 17 normotensive pregnant, and 11 preeclamptic women who were clinically diagnosed without history of diabetic neuropathy, cardiac arrhythmia, and other cardiovascular diseases. Frequency-domain analysis of short-term, stationary R-R intervals was performed to evaluate the total variance, low-frequency power (LF; 0.04-0.15 Hz), high-frequency power (HF; 0.15-0.40 Hz), ratio of LF to HF (LF/HF), and LF in normalized units (LF%). Natural logarithm transformation was applied to variance, LF, HF, and LF/HF for the adjustment of the skewness of distribution. We found that the normal pregnant group had a lower R-R value and HF but had a higher LF/HF and LF% compared with the nonpregnant group. The preeclamptic group had lower HF but higher LF/HF compared with either the normal pregnant or nonpregnant group. Our results suggest that normal pregnancy is associated with a facilitation of sympathetic regulation and an attenuation of parasympathetic influence of heart rate, and such alterations are enhanced in preeclamptic pregnancy.     

A randomized,double-masked,placebo-controlled crossover trial on the effects of L-ornithine on salivary cortisol and feelings of fatigue of flushers the morning after alcohol consumption

Background

Residual alcohol effects on physiological and psychological symptoms are commonly experienced the morning after alcohol consumption. The purpose of this study was to assess the effects of L-ornithine on subjective feelings and salivary stress markers the morning after alcohol consumption and to investigate whether L-ornithine acutely accelerates ethanol metabolism.

Methods

This study had a randomized, placebo-controlled, double-masked crossover design. Subjects were all healthy Japanese adults with the ‘flusher’ phenotype for alcohol tolerance. In experiment 1, 11 subjects drank 0.4 g/kg body weight alcohol 1.5 h before their usual bedtime. Half an hour after drinking, they ingested either a placebo or 400 mg ornithine. The next morning on awakening, subjects completed a questionnaire containing a visual analog scale (VAS), the Oguri-Shirakawa-Azumi sleep inventory MA version (OSA-MA), and a profile of mood states (POMS) and collected a saliva sample for measurement of salivary stress markers (cortisol, secretory immunoglobulin A, and α-amylase). In experiment 2, placebo or 400 mg ornithine were administrated to 16 subjects both before and after drinking, and the feeling of drunkenness, breath ethanol concentration and one-leg standing time were repeatedly investigated until 180 min after alcohol consumption.

Results

There were significant decreases in “awareness”, “feeling of fatigue” and “lassitude” VAS scores and in “anger-hostility” and “confusion” POMS scores and a significant increase in “sleep length” in the OSA-MA test. Salivary cortisol concentrations on awakening were reduced after ornithine supplementation. There were no differences between ornithine and placebo in any of the subjective or physiological parameters of acute alcohol metabolism.

Conclusions

Taking 400 mg ornithine after alcohol consumption improved various negative feelings and decreased the salivary stress marker cortisol the next morning. These effects were not caused by an increase in acute alcohol metabolism.

     

Low to high frequency ratio of heart rate variability spectra fails to describe sympatho-vagal balance in cardiac patients

Heart rate variability (HRV) reflects an influence of autonomic nervous system on heart work. In healthy subjects, ratio between low and high frequency components (LF/HF ratio) of HRV spectra represents a measure of sympatho-vagal balance. The ratio was defined by the authorities as an useful clinical tool, but it seems that it fails to summarise sympatho-vagal balance in a clinical setting. Value of the method was re-evaluated in several categories of cardiac patients. HRV was analysed from 24-hour Holter ECGs in 132 healthy subjects, and 2159 cardiac patients dichotomised by gender, median of age, diagnosis of myocardial infarction or coronary artery surgery, left ventricular systolic function and divided by overall HRV into several categories. In healthy subjects, LF/HF ratio correlated with overall HRV negatively, as expected. The paradoxical finding was obtained in cardiac patients; the lower the overall HRV and the time-domain indices of vagal modulation activity were the lower the LF/HF ratio was. If used as a measure of sympatho-vagal balance, long-term recordings of LF/HF ratio contradict to clinical finding and time-domain HRV indices in cardiac patients. The ratio cannot therefore be used as a reliable marker of autonomic activity in a clinical setting.     

Effects of recombinant human thyrotropin on heart rate variability and blood pressure in patients on l-thyroxine-suppressive therapy for differentiated thyroid carcinoma

BACKGROUND: Recombinant human thyrotropin (rhTSH) is now currently used for the follow-up of patients with differentiated thyroid carcinoma (DTC) after total thyroid ablation. Side effects after rhTSH could involve the autonomic system and TSH receptors are possibly expressed in the heart and coronary arteries. METHODS:Heart rate variability (HRV), studied by power spectral analysis of low (LF) and high frequency (HF) powers, blood pressure (BP) and their responses to orthostatism were investigated before and 3, 6, 9 days after the first of two administrations of rhTSH on alternate days in 11 patients on chronic l-thyroxine (l-T4) suppressive therapy for DTC and in 31 healthy controls. RESULTS: A transient asymptomatic decrease in systolic and mean BP was observed during the rhTSH test, but rhTSH did not modify sympathovagal control of HRV and the lying to standing responses. Decreased LF power and LF/(LF + HF) and LF/HF ratios in DTC patients versus healthy controls indicated a sympathetic failure ascribed to the TSH-suppressive therapy with l-T4 rather than to direct effects of rhTSH. CONCLUSIONS: These findings allowed us to confirm the cardiovascular safety of rhTSH and the absence of its effects on sympathovagal control of HRV when used in the follow-up of patients with normal heart function after thyroid ablation for DTC.