| 1. |
- Krämer, Heidrun H, et al.
(författare)
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Central correlation of muscle sympathetic nerve activation during baroreflex unloading - a microneurography-positron emission tomography study
- 2014
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Ingår i: European Journal of Neuroscience. - : Wiley. - 0953-816X .- 1460-9568. ; 39:4, s. 623-629
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Tidskriftsartikel (refereegranskat)abstract
- The baroreceptor reflex controls spontaneous fluctuations in blood pressure. One major control variable of the baroreflex is the sympathetic vasoconstrictor activity to muscles [MSNA; burst frequency (BF) and burst incidence (BI)], which can be quantitatively assessed by microneurography. We aimed to investigate the central regions involved in baroreflex regulation of MSNA. Healthy men (mean age 25 years) participated in three experimental sessions. (i) Microneurography recordings of MSNA from the left peroneal nerve during rest and baroreflex unloading, induced by lower body negative pressure (LBNP; -40 mmHg). If MSNA could be reliably recorded throughout this procedure (n = 15), the subjects entered the positron emission tomography (PET) experiments. The two PET sessions took place in a randomised order. Cerebral glucose metabolism (18-fluorodeoxyglucose) was analysed after: (ii) baroreflex unloading (LBNP); and (iii) control condition (lying in the LBNP chamber without suction). The PET data were analysed employing SPM8. LBNP elicited a significant increase in MSNA in all successfully recorded subjects (BI: P = 0.001; F = 5.54; BF: P < 0.001; F = 36.59). As compared with the control condition, LBNP was associated with increased PET regional glucose metabolism bilaterally in the orbitofrontal cortex (OFC; BA 11, 47). Related to the rise of BF, there was increased activation of the left OFC (BA 11); related to the rise of BI there was increased activation of the brainstem corresponding to the rostral ventrolateral medulla. Our data support a role for the ventrolateral medulla and the OFC in baroreflex-mediated control of MSNA in humans. © 2013 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.
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| 2. |
- Mannaert, H., et al.
(författare)
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Foreword
- 2011
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Ingår i: 3rd International Conference on Mobile, Hybrid, and On-Line Learning, eL and mL 2011. - 2308-4367.
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Tidskriftsartikel (refereegranskat)
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| 3. |
- Schreyer, A. -M, et al.
(författare)
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Experimental flow studies on separation and reattachment in the vicinity of sharp,wedge shaped leading edges at low Reynolds numbers
- 2010
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Ingår i: New Results In Numerical And Experimental Fluid Mechanics VII. - Berlin, Heidelberg : Springer Berlin/Heidelberg. - 9783642142420 ; , s. 273-280
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Konferensbidrag (refereegranskat)abstract
- The flow field around sharp leading edges in subsonic, low Reynolds number flow is investigated experimentally. Separation occurs already at small angles of attack. Under certain conditions reattachment takes place and a separation bubble develops. As this influences the lift and drag of an airfoil decisively, the conditions leading to reattachment and the formation of a laminar boundary layer are of special interest. The influences of the Reynolds number, angle of attack and leading edge apex angle on the boundary layer properties are studied by means of hot-wire anemometry, flow visualisation techniques and measurements of the pressure distribution over the leading edge. For a small parameter range, laminar separation followed by laminar reattachment is observed.
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