| 1. |
- Wallin, Gunnar B, 1936, et al.
(författare)
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Sympathetic single axonal discharge after spinal cord injury in humans: activity at rest and after bladder stimulation
- 2014
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Ingår i: Spinal Cord. - : Springer Science and Business Media LLC. - 1362-4393 .- 1476-5624. ; 52:6, s. 434-438
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Tidskriftsartikel (refereegranskat)abstract
- Study design: Clinical experimental mechanistic study. Objectives: (1) To determine in three spinal cord-injured patients whether individual muscle sympathetic nerve fibres below the level of the spinal lesion display spontaneous activity. (2) To determine in these patients if individual sympathetic vasoconstrictor fibres show a prolonged discharge following a bladder stimulus. Methods: Microneurographic recordings of action potentials from individual muscle nerve sympathetic fibres in a peroneal nerve. Recordings of skin blood flow and electrodermal responses in a foot. Results: In all patients, there was sparse ongoing spontaneous impulse traffic in individual sympathetic fibres. Brisk mechanical pressure over the urinary bladder evoked a varying number of action potentials in individual fibres, but the activity was brief and did not continue after the end of the evoked multiunit burst. Conclusion: Prolonged discharges in individual sympathetic fibres are unlikely to contribute to a long duration of blood pressure increases induced by brief bladder stimuli.
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| 2. |
- Donadio, Vincenzo, et al.
(författare)
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Arousal elicits exaggerated inhibition of sympathetic nerve activity in phobic syncope patients.
- 2007
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Ingår i: Brain : a journal of neurology. - : Oxford University Press (OUP). - 1460-2156. ; 130:Pt 6, s. 1653-62
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Tidskriftsartikel (refereegranskat)abstract
- Alerting stimuli causing arousal have been shown to elicit a reproducible transient inhibition of muscle sympathetic nerve activity (MSNA) in healthy subjects. The aim of the present study was to test whether this inhibitory response to arousal is exaggerated in patients with a history of vasovagal syncope. We studied 24 untreated syncope patients, 12 of whom met the DSM-IV-TR diagnostic criteria for blood/injury phobia and 18 age-matched healthy subjects. MSNA was recorded from the peroneal nerve at the fibular head. Arousal was induced by randomly presented trains of five electrical pulses delivered to a finger. The pulses were triggered on five consecutive R waves of the ECG, with a delay of 200 ms. Patients also underwent cardiological and neurological examinations, tilt test and a structured interview to investigate diagnostic criteria for specific phobia. The syncope patients had significantly lower resting MSNA (29 +/- 2 bursts/min) and diastolic blood pressure (BP, 78 +/- 2 mmHg) compared to controls (36 +/- 2 bursts/min and 84 +/- 3 mmHg; P < 0.05), whereas no significant differences were found for resting heart rate and systolic BP. The phobic patient group exhibited prolonged sympathetic inhibitions to arousal stimuli compared to controls and non-phobic patients, whereas no difference was found between tilt-positive and tilt-negative patients or between controls and non-phobic patients. The findings suggest that the degree of inhibition in response to arousal stimuli is related to a subjective factor coupled to fear of blood/injury. The exaggerated inhibition in patients with phobia to blood/injury may be a factor predisposing to syncope in those patients.
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| 3. |
- Donadio, Vincenzo, et al.
(författare)
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Daytime sympathetic hyperactivity in OSAS is related to excessive daytime sleepiness.
- 2007
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Ingår i: Journal of sleep research. - : Wiley. - 0962-1105 .- 1365-2869. ; 16:3, s. 327-32
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to investigate the relationships among sympathetic hyperactivity, excessive daytime sleepiness (EDS) and hypertension in obstructive sleep apnoea syndrome (OSAS). Ten newly diagnosed OSAS patients with untreated EDS and daytime hypertension underwent polysomnography (PSG) and daytime measurements of plasma noradrenaline (NA), ambulatory blood pressure (BP), muscle sympathetic nerve activity (MSNA) by microneurography and objective assessment of EDS before and during 6 months of compliance-monitored continuous positive airway pressure (CPAP) treatment. One month after the start of CPAP, BP, MSNA and NA were significantly lowered, remaining lower than baseline also after 3 and 6 months of treatment. CPAP use caused a significant improvement of sleep structures, and reduced EDS. A statistical correlation analysis demonstrated that EDS was not correlated with sleep measures obtained from baseline PSG (% sleep stages, apnoea and arousal index, mean oxygen saturation value), whereas daytime sleepiness was significantly correlated with MSNA. Furthermore, MSNA and BP showed no correlation. Our data obtained from selected patients suggest that the mechanisms inducing EDS in OSAS are related to the degree of daytime sympathetic hyperactivity. Additionally, resting MSNA was unrelated to BP suggesting that factors other than adrenergic neural tone make a major contribution to OSAS-related hypertension. The results obtained in this pilot study need, however, to be confirmed in a larger study involving more patients.
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| 4. |
- Donadio, V., et al.
(författare)
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Muscle sympathetic response to arousal predicts neurovascular reactivity during mental stress
- 2012
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Ingår i: Journal of Physiology-London. - : Wiley. - 0022-3751. ; 590:12, s. 2885-2896
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Tidskriftsartikel (refereegranskat)abstract
- Key points Mental stress (MS) is often initiated by a sensory or cognitive stimulus, which induces a brief arousal reaction followed by a longer stress phase. Both phases induce blood pressure (BP) increases whereas effects on muscle sympathetic nerve activity (MSNA) vary: in approximately 50% of healthy subjects (responders) arousal induces a brief MSNA reduction, which is absent in the remaining 50% (non-responders). We now report a link between the arousal response and neurovascular effects of MS in healthy males. Our data show that during MS, responders to arousal exhibited a significant decrease of MSNA and a lesser BP increase compared to non-responders. The whole material displayed a positive correlation between MSNA responses induced by arousal and MS. In addition, arousal induced MSNA changes correlated positively with BP changes during MS. We conclude that the MSNA response to arousal predicts MSNA and BP responses to MS.
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| 5. |
- Donadio, Vincenzo, et al.
(författare)
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Sympathetic and cardiovascular activity during cataplexy in narcolepsy.
- 2008
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Ingår i: Journal of sleep research. - : Wiley. - 1365-2869 .- 0962-1105. ; 17:4, s. 458-63
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Tidskriftsartikel (refereegranskat)abstract
- Autonomic nervous system activity changes have been described during cataplexy as playing a role in triggering it. To confirm these previous findings, we investigated the time course of sympathetic and cardiovascular activities during cataplexy. We made for the first time microneurographic recordings of 10 cataplectic episodes in three patients with hypocretin-deficient narcolepsy. During microneurography, muscle sympathetic nerve activity (MSNA) was recorded simultaneously with heart rate (HR), respiratory movements, arterial finger blood pressure (BP), electroencephalography, electro-oculogram and superficial electromyogram. Results showed no significant autonomic changes before the onset of the cataplectic episodes. Cataplexy was associated with a significant increase in MSNA and BP compared with baseline, whereas HR was markedly decreased. An irregular breathing pattern mainly characterized by apnea typically occurred during the attacks. In conclusion, our findings did not show significant changes in autonomic activity prior to cataplexy onset, ruling out a triggering role of the autonomic system. However, cataplexy was associated with co-activation of sympathetic and parasympathetic autonomic systems, a pattern reminiscent of that reported during the vigilance reaction in animals.
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| 6. |
- Engström, Tomas, 1950, et al.
(författare)
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Effektiv småbåtsproduktion. Delrapport
- 1984
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Consumer report ("avnämarrapport" in Swedish) for a research foundation (Styrelsen för Teknisk Utveckling, Stockholm). A comment: Publishing consumer reports was the praxis during this (early) period of time at Chalmers University of Technology, as well as probably at some other universities. This means that frequent and vast academic publication by means of e.g. conference papers and refereed contributions to scientific journals was almost unheard of. At least so for some of the applied science disciplines. However, today are the situation indeed very different (i.e. earlier was the publication in many respects focused on trying to satisfy the executive administrator the research foundation in question etc.). To be more precise, this early praxis was definitively the case for the research and development work carried out at the Department of Transportation (a broadly applied science discipline), which was characterized by more practical strives to e.g. engineer research results. Rather than relying on truer scientific efforts in a narrower sense. Functional satisfaction (i.e. something engineered work as planned instead verification/falsification of a hypothesis) was judged as being a primary aim of this research and development work. Therefore are (in the context of the publications registered in Chalmers Public Library CPL) the author making distinctions between consumer reports, on one hand. And, one the other hand, reports and preprints (manuscripts), while instead the academically orientated publications are various sort of scientific contributions presented at conferences or published in scientific journals (actually it is somewhat more complex, but further explanations are omitted here). The consumer reports were aimed at a various external organization with who the authors cooperated, and these are in many cases not available in PDF format to be easily read by logging in at CPL. This particular approach has judged as being fair/relevant fair in order to mirror of work conducted by the author or authors during the passing decades. Besides, the competencies at Chalmers Library, who actually have been very helpful, have not managed to provide appropriate answers to the various questions implied being at hand just above (this despite trying to get hold of such answers, hence this very comment).
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| 7. |
- Hart, Emma C, et al.
(författare)
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Baroreflex control of muscle sympathetic nerve activity: a nonpharmacological measure of baroreflex sensitivity.
- 2010
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Ingår i: American journal of physiology. Heart and circulatory physiology. - : American Physiological Society. - 1522-1539 .- 0363-6135. ; 298:3, s. H816-22
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Tidskriftsartikel (refereegranskat)abstract
- The sensitivity of baroreflex control of sympathetic nerve activity (SNA) represents the responsiveness of SNA to changes in blood pressure. In a slightly different analysis, the baroreflex threshold measures the probability of whether a sympathetic burst will occur at a given diastolic blood pressure. We hypothesized that baroreflex threshold analysis could be used to estimate the sensitivity of the sympathetic baroreflex measured by the pharmacological modified Oxford test. We compared four measures of sympathetic baroreflex sensitivity in 25 young healthy participants: the "gold standard" modified Oxford analysis (nitroprusside and phenylephrine), nonbinned spontaneous baroreflex analysis, binned spontaneous baroreflex analysis, and threshold analysis. The latter three were performed during a quiet baseline period before pharmacological intervention. The modified Oxford baroreflex sensitivity was significantly related to the threshold slope (r = 0.71, P < 0.05) but not to the binned (1 mmHg bins) and the nonbinned spontaneous baroreflex sensitivity (r = 0.22 and 0.36, respectively, P > 0.05), which included burst area. The threshold analysis was also performed during the modified Oxford manipulation. Interestingly, we found that the threshold analysis results were not altered by the vasoactive drugs infused for the modified Oxford. We conclude that the noninvasive threshold analysis technique can be used as an indicator of muscle SNA baroreflex sensitivity as assessed by the modified Oxford technique. Furthermore, the modified Oxford method does not appear to alter the properties of the baroreflex.
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| 8. |
- Hart, Emma C, et al.
(författare)
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Hysteresis in the sympathetic baroreflex: role of baseline nerve activity.
- 2011
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Ingår i: The Journal of physiology. - : Wiley. - 1469-7793 .- 0022-3751. ; 589:Pt 13, s. 3395-404
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Tidskriftsartikel (refereegranskat)abstract
- Sympathetic baroreflex sensitivity (BRS) is greater during decreasing compared to increasing diastolic blood pressure (DBP) in young men and women. In older men and women there is no difference in sympathetic BRS to increasing and decreasing DBP. We investigated whether the sensitivity of the central nervous system to increasing and decreasing DBP is dependent upon baseline muscle sympathetic nerve activity (MSNA). We hypothesised that the difference in sympathetic BRS between falling and rising segments of DBP would be positively related to baseline MSNA in 30 young men, 21 young women, 14 older men and 14 postmenopausal women. MSNA was measured using peroneal microneurography and BRS was measured using the spontaneous baroreflex threshold technique. On average, sympathetic BRS was greater during decreasing compared to increasing DBP in young men (P <0.05) and women (P <0.05). In older men and women, mean sympathetic BRS was similar in response to increasing and decreasing DBP. The difference (delta) between the falling and rising BRS correlated with baseline MSNA in young (r =0.58, P <0.05) and older men (r =0.66, P <0.05) and postmenopausal women (r =0.74, P <0.05). Thus, all men, and older women, with higher BRS to falling DBP had lower baseline MSNA. This relationship was not observed in young women (r =0.14, P >0.05). In summary, baseline MSNA plays a role in determining sympathetic BRS to falling and rising DBP in young and older men and postmenopausal women, but not in young women. This relationship is consistent with a decreased potential for sympathoexcitation in people with higher resting MSNA. Furthermore, the lack of relationship in young women suggests important contributions of sex hormones to differential responses of MSNA to falling and rising pressures.
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| 9. |
- Johansson, Peter E., Associate professor, 1978-, et al.
(författare)
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Let us measure, then what? : Exploring purposeful use of innovation management self-assessments.
- 2019
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Ingår i: International Journal of Quality & Reliability Management. - 0265-671X .- 1758-6682. ; 36:10, s. 1734-1749
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Tidskriftsartikel (refereegranskat)abstract
- PurposeThe purpose of this paper is to increase the understanding regarding how managers attempt to make purposeful use of innovation management self-assessments (IMSA) and performance information (PI).Design/methodology/approachAn interpretative perspective on purposeful use is used as an analytical framework, and the paper is based on empirical material from two research projects exploring the use of IMSA and PI in three case companies. Based on the empirical data, consisting of interviews and observations of workshops and project meetings, qualitative content analysis has been conducted.FindingsThe findings of this paper indicate that how managers achieve a purposeful use of PI is related to their approach toward how to use the specific PI at hand, and two basic approaches are analytically separated: a rule-based approach and a reflective approach. Consequently, whether or not the right thing is being measured also becomes a question of how the PI is actually being interpreted and used. Thus, the extensive focus on what to measure and how to measure it becomes edgeless unless equal attention is given to how managers are able to use the PI to make knowledgeable decisions regarding what actions to take to achieve the desired changes.Practical implicationsGiven the results, it comes with a managerial responsibility to make sure that all managers who are supposed to be engaged in using the PI are given roles in the self-assessments that are aligned with the level of knowledge they possess, or can access.Originality/valueHow managers purposefully use PI is a key to understand the potential impact of self-assessments.
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| 10. |
- Jonsson Eskelin, John, 1987, et al.
(författare)
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From MEG to clinical EEG: evaluating a promising non-invasive estimator of defense-related muscle sympathetic nerve inhibition
- 2023
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Ingår i: Scientific Reports. - 2045-2322. ; 13:1
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Tidskriftsartikel (refereegranskat)abstract
- Sudden, unexpected stimuli can induce a transient inhibition of sympathetic vasoconstriction to skeletal muscle, indicating a link to defense reactions. This phenomenon is relatively stable within, but differs between, individuals. It correlates with blood pressure reactivity which is associated with cardiovascular risk. Inhibition of muscle sympathetic nerve activity (MSNA) is currently characterized through invasive microneurography in peripheral nerves. We recently reported that brain neural oscillatory power in the beta spectrum (beta rebound) recorded with magnetoencephalography (MEG) correlated closely with stimulus-induced MSNA inhibition. Aiming for a clinically more available surrogate variable reflecting MSNA inhibition, we investigated whether a similar approach with electroencephalography (EEG) can accurately gauge stimulus-induced beta rebound. We found that beta rebound shows similar tendencies to correlate with MSNA inhibition, but these EEG data lack the robustness of previous MEG results, although a correlation in the low beta band (13-20 Hz) to MSNA inhibition was found (p = 0.021). The predictive power is summarized in a receiver-operating-characteristics curve. The optimum threshold yielded sensitivity and false-positive rate of 0.74 and 0.33 respectively. A plausible confounder is myogenic noise. A more complicated experimental and/or analysis approach is required for differentiating MSNA-inhibitors from non-inhibitors based on EEG, as compared to MEG.
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