摘要 :
AimsTo investigate eclampsia and pre-eclampsia electroencephalograms (EEGs) and related animal experiments, and to publish a Japanese article in English.
摘要 :
BACKGROUND: Preeclampsia is associated with enhanced sympathetic activity as well as subnormal plasma volume. Meanwhile, in over 50% of these complicated pregnancies, the subnormal plasma volume has been found to persist for a pro...
展开
BACKGROUND: Preeclampsia is associated with enhanced sympathetic activity as well as subnormal plasma volume. Meanwhile, in over 50% of these complicated pregnancies, the subnormal plasma volume has been found to persist for a prolonged period after pregnancy. The objective of this study is to test the hypothesis that in normotensive formerly-preeclamptic women, persistence of a subnormal plasma volume coincides with enhanced sympathetic activity and with it, an altered autonomic control of blood pressure. METHODS: Forty-eight formerly-preeclamptic women participated in this study. After measurement of their plasma volume by iodine 125-albumin indicator dilution, they were subdivided into a group with a normal plasma volume (plasma volume > 48 ml/kg lean body mass) and a group with a subnormal plasma volume (< or = 48 ml/kg lean body mass). We performed spectral analysis on their beat-to-beat blood pressure and heart rate recordings and compared both groups using non-parametric tests. RESULTS: Formerly-preeclamptic women with a subnormal plasma volume had a higher sympathetic activity (P = .001) and a lower baroreflex sensitivity (P = .04) than their counterparts with a normal plasma volume. CONCLUSION: In normotensive formerly-preeclamptic women, a subnormal plasma volume coincides with a higher sympathetic activity in the blood pressure regulation and lower baroreflex sensitivity. Whether these alterations in the autonomic control mechanisms are a cause or effect of the subnormal plasma volume remains to be elucidated.
收起
摘要 :
Objectives: Recent studies have shown that both innate and adaptive immunity response contributes to vascular dysfunction by vascular remodelling and later hypertension. Furthermore, the sympathetic activity mediates the vascular ...
展开
Objectives: Recent studies have shown that both innate and adaptive immunity response contributes to vascular dysfunction by vascular remodelling and later hypertension. Furthermore, the sympathetic activity mediates the vascular dysfunction through pro-inflammatory activity of immune system. In context to insidious onset hypertension, the study was planned to observe the association of immunity with the increased sympathetic activity in pre-hypertensive adults. Materials and Methods: Thirty healthy pre-hypertensive (as per JNC VII) non-smokers, non-alcoholic and non-obese male adults volunteers were recruited from the study area. Equal numbers of normotensive controls were taken for comparison. On reporting day, they were subjected to the recording of demographic and anthropometric measurements, hand grip dynamometry and later investigated for serum levels of interleukin-17 (IL-17) and high-sensitivity C-reactive proteins (hsCRP) after written informed consent. The data collected were analysed for differences in mean and association of immune and inflammatory markers with sympathetic activity by statistical tests. Results: Significantly higher values of weight, BMI, % BF, visceral fat, resting heart rate and IL-17 and a lower sympathetic reactivity was observed in pre-hypertensive subjects. Values of hsCRP was higher in prehypertensive but was not statistically significant. IL-17 was a positive significant predictor with 4.7 times (P = 0.02) increase in odds of being pre-hypertensive, whereas sympathetic reactivity was a significant negative predictor (OR = 0.75; P = 0.001). SBP and DBP are both related negatively and significantly (P < 0.05) to the sympathetic reactivity suggesting that blood pressure is related to sympathetic nervous system. Furthermore, the hsCRP is observed to be related positively to the % BF and to only SBP and RHR, complimenting link of adiposity as an inflammatory process to blood pressure. IL-17 levels in blood are observed to be positively and significantly related to DBP. Conclusion: Elevated IL-17 levels are significant predictor of pre-hypertension along with lower sympathetic reactivity. No direct association was observed between IL-17 and sympathetic system except with raised DBP. Immune mechanism is part of pathogenesis of increased blood pressure in pre-hypertensive with enhanced baseline sympathetic activity.
收起
摘要 :
An understanding of the explosive's shock sensitivity is of vital importance for the hazard assessment and vulnerability evaluations of munitions. This paper summarizes the experimental and modeling research relating to shock init...
展开
An understanding of the explosive's shock sensitivity is of vital importance for the hazard assessment and vulnerability evaluations of munitions. This paper summarizes the experimental and modeling research relating to shock initiation and sympathetic reaction of PBXN-109. The modeling has focused on developing and applying Ignition and Growth (I&G) models using the hydrocode LS-DYNA, taking into consideration the reduced shock sensitivity due to changes in source of ingredients. Detonation front tracking was applied to selected sympathetic reaction experiments and one Large Scale Gap Test series to extract additional information of the response of the acceptor charges. The simulated arrival times were compared with the measured data at the fibreoptic array positions. Finally, the shock sensitivity curve that summarizes the critical combination of peak shock pressure P and the derived parameter P(2)t was described for the PBXN-109 formulations and compared with curves reported for other explosives.
收起
摘要 :
An experiment assessed the joint effect of dispositional need for closure (NFC) and task difficulty on engagement-related myocardial beta-adrenergic activity. Participants who scored either low or high on the NFC scale performed a...
展开
An experiment assessed the joint effect of dispositional need for closure (NFC) and task difficulty on engagement-related myocardial beta-adrenergic activity. Participants who scored either low or high on the NFC scale performed an ambiguous categorization task with either low or high difficulty. Confirming the theory-derived predictions, task difficulty effects on pre-ejection period (PEP) reactivity were moderated by NFC. If difficulty was low, PEP reactivity was low and independent of the participants' NFC level. If difficulty was high, participants with high NFC showed increased PEP reactivity compared to participants with low NFC. These results extend previous research on Wright's model of engagement-related cardiovascular reactivity and suggest that the model may provide a useful framework for assessing the impact of personality on cardiovascular response.
收起
摘要 :
Stress is a well-known factor affecting cardiac contractility through the cardiac sympathetic nerves. A positive inotropic effect of the cardiac sympathetic nerves on the myocardium is reflected by pre-ejection period (PEP) shorte...
展开
Stress is a well-known factor affecting cardiac contractility through the cardiac sympathetic nerves. A positive inotropic effect of the cardiac sympathetic nerves on the myocardium is reflected by pre-ejection period (PEP) shortening. Patients with Parkinson disease (PD) and neurogenic orthostatic hypotension (NOH) (PD + NOH) or with pure autonomic failure (PAF) have markedly decreased myocardial 6-[~(18)F]Fluorodopamine-derived radioactivity, reflecting cardiac sympathetic denervation. The functional effects of the cardiac sympathetic denervation have been unknown. We measured PEP and heart rate-corrected PEP (PEPI) responses to i.v. tyramine (1 mg/min) in 13 patients (9 PD + NOH and 4 PAF) with low 6-[~(18)F]Fluorodopamine-derived radioactivity and in subjects with normal radioactivity (15 multiple system atrophy with NOS patients (MSA + NOS). Baseline PEP and PEPI did not differ between the groups. By 10 min after initiation of tyramine infusion, PEP and PEPI were significantly lower (P < 0.01) in MSA + NOS, compared to base line, whereas PEP and PEPI remained unchanged in the PD + NOH/PAF group. The PEP and PEPI decrease was larger in the MSA + NOS group than in the PD + NOH/PAF group (P < 0.05). One of the functional consequences of cardiac sympathetic denervation is failure to increase contractility in response to stimuli that depend on endogenous norepinephrine release.
收起
摘要 :
The Poincaré plot is a visual representation of the R-R time series within a Cartesian plane constructed by plotting each R-R interval as a function of the previous one. The plot can be characterized by parameters that quantify t...
展开
The Poincaré plot is a visual representation of the R-R time series within a Cartesian plane constructed by plotting each R-R interval as a function of the previous one. The plot can be characterized by parameters that quantify the standard deviation (SD) of short- and long-term R-R interval variability (SD1 and SD2, respectively). Claims regarding the use of Poincaré plot analysis as an alternative to conventional time-domain and spectral analytic measures of parasympathetic contributions to heart rate variability (HRV) have been evaluated somewhat extensively. However, its proposed utility for characterizing sympathetic influences on HRV during periods of acute mental stress, using SD2 and the SD1/SD2 ratio, has received minimal attention. In the present study, the electrocardiogram was used to record R-R interval variability in healthy participants during a resting baseline period, while they performed a challenging reaction time task, and then during a recovery period. Simultaneously, the thoracic impedance cardiogram was used to derive the pre-ejection period (PEP), which reflects sympathetic cardiac control. HRV was quantified using time-domain, spectral analytic, and Poincaré plot indices. Task performance elicited significant reductions in HRV and PEP parameters, indicating withdrawal of parasympathetic tone with concomitant sympathetic activation. Following cessation of task performance, all HRV and impedance measures returned to baseline levels, signaling resumption of parasympathetic dominance. Bivariate associations linking SD2 and the SD1/SD2 ratio to PEP were observed; however, these were not large in magnitude, were exceeded in size by associations between the Poincaré metrics and conventional HRV markers of parasympathetic cardiac influences, and were eliminated when the latter were controlled statistically. These observations challenge the proposal that the Poincaré SD2 and SD1/SD2 metrics are suitable markers of sympathetic cardiac regulation in research concerned with mental and physical health.
收起
摘要 :
Research on listening effort has used various physiological measures to examine the biological correlates of listening effort but a systematic examination of the impact of listening demand on cardiac autonomic nervous system activ...
展开
Research on listening effort has used various physiological measures to examine the biological correlates of listening effort but a systematic examination of the impact of listening demand on cardiac autonomic nervous system activity is still lacking. The presented study aimed to close this gap by assessing cardiac sympathetic and parasympathetic responses to variations in listening demand. For this purpose, 45 participants performed four speech-in-noise tasks differing in listening demand-manipulated as signalto-noise ratio varying between + 23 dB and-16 dB-while their pre-ejection period and respiratory sinus arrythmia responses were assessed. Cardiac responses showed the expected effect of listening demand on sympathetic activity, but failed to provide evidence for the expected listening demand impact on parasympathetic activity: Pre-ejection period reactivity increased with increasing listening demand across the three possible listening conditions and was low in the very high (impossible) demand condition, whereas respiratory sinus arrythmia did not show this pattern. These findings have two main implications. First, cardiac sympathetic responses seem to be the more sensitive correlate of the impact of task demand on listening effort compared to cardiac parasympathetic responses. Second, very high listening demand may lead to disengagement and correspondingly low effort and reduced cardiac sympathetic response. (c) 2021 Elsevier B.V. All rights reserved.
收起
摘要 :
Aim: Endothelin-1 (ET-1) plays an important role in the pathogenesis of salt-dependent forms of hypertension in adult rats, but its participation in salt hypertension elicited in immature rats is still unknown. Therefore, we compa...
展开
Aim: Endothelin-1 (ET-1) plays an important role in the pathogenesis of salt-dependent forms of hypertension in adult rats, but its participation in salt hypertension elicited in immature rats is still unknown. Therefore, we compared ET-1 role in the development or the maintenance of salt hypertension induced in young (4-week-old) or adult (12-week-old) Dahl rats. Methods: The contribution of pressor ET-1 effects to the maintenance of high blood pressure (BP) was studied using acute injection of ET A receptor antagonist ambrisentan (BSF 208075, 1 mg kg -1 iv) to young or adult rats with established salt hypertension. Furthermore, using chronic ambrisentan treatment (30 mg kg -1 day -1 in the drinking fluid during 5 weeks of high salt intake), we investigated the age-dependent involvement of ET A receptors in salt hypertension development in these two age groups. Results: Acute ET A receptor blockade lowered BP in both age groups of salt hypertensive Dahl rats more than in rats fed a low-salt diet (but without any age-dependent difference). Chronic ET A receptor blockade strongly attenuated the development of salt hypertension and cardiac hypertrophy in adult rats, but it had no significant effects on salt hypertension in young animals. Pronounced BP reduction induced in adult salt hypertensive rats by chronic ambrisentan treatment was attributed to attenuated sympathetic BP component, without changes in nitric oxide (NO)-dependent BP regulation. In contrast, chronic ambrisentan treatment of young animals did not modify sympathetic BP component but substantially attenuated NO-dependent vasodilatation. Conclusions: ET A receptor-mediated ET-1 effects play an important role in salt hypertension of adult but not young Dahl rats.
收起
原文获取