| 1. |
- Golster, Helena, et al.
(författare)
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Heterogeneous blood flow response in the foot on dependency, assessed by laser Doppler perfusion imaging
- 1997
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Ingår i: Acta Physiologica Scandinavica. - 0001-6772 .- 1365-201X. ; 159:2, s. 101-106
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Tidskriftsartikel (refereegranskat)abstract
- The exact nature of the decrease in foot skin blood flow seen after a change in posture remains unsettled. This mechanism has previously been examined by non-invasive techniques such as the laser Doppler perfusion monitor (laser Doppler flowmetry). Taking into account the shortcomings of laser Doppler perfusion monitoring when applied to the determination of skin blood flow, which normally shows substantial heterogeneity, we have applied an emerging technology, the laser Doppler perfusion imager (LDPI). This technique provides a more comprehensive picture of the blood flow distribution in the skin, as it maps skin blood flow over a surface area (120×120 mm, 4096 measurement sites). It was used to examine if the reduction in tissue perfusion or the alterations in flow distributions seen after a change in posture (supine to dependency) could be fully explained by an increase in venous pressure (venous stasis of 50 mmHg) or if the data suggest a complementary mechanism.Skin blood flow of the forefoot decreased from 0.60 V (volt) (median) during rest to 0.40 and 0.38 V during venous stasis and dependency, respectively. Although almost identical median values were obtained during stasis and dependency, the flow distributions were different, with a loss of high flow values during venous stasis. Biological zero was 0.24 V.As the LDPI technique readily records skin perfusion during variations in venous stasis and posture, as well as information on flow distribution changes, it appears promising for future application in stimuli-response studies of skin blood flow. The difference in flow distribution seen between increased venous pressure and dependency suggests an additive regulatory mechanism to the veni-vasomotor reflex during a change in posture.
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| 2. |
- Jönsson, Björn, 1951-, et al.
(författare)
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Is oscillometric ankle pressure reliable in leg vascular disease?
- 2001
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Ingår i: Clinical Physiology and Functional Imaging. - : Wiley. - 1475-0961 .- 1475-097X. ; 21:2, s. 155-163
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Tidskriftsartikel (refereegranskat)abstract
- The objective of the study was to evaluate the validity of oscillometric systolic ankle pressure in symptomatic leg arterial occlusive disease. Ankle pressure measurements using oscillometric curves obtained using a standard 12-cm cuff with a specially designed device for signal processing were validated against the continuous wave (CW) Doppler technique. Thirty-four subjects without signs or symptoms of peripheral vascular disease (68 legs) and 47 patients with leg ischaemia (85 legs) varying from moderate claudication to critical ischaemia were examined. The oscillometric curves were analysed using several algorithms reported in the literature, based on the assumption that maximum oscillations are recorded near mean arterial pressure. In normals, reasonable agreement between CW Doppler and oscillometric methods was seen. When an algorithm that determined the lowest cuff pressure at which maximum oscillations occurred, and a characteristic ratio for systolic pressure of 0·52 was used, the mean difference between CW Doppler and oscillometry was 1·7 mmHg [range −19 to +27, limits of agreement (2 SD) 21·1 mmHg]. In ischaemic legs, oscillometry overestimated systolic ankle pressure by a mean of 28·8 mmHg [range –126 to +65, limits of agreement 82·8 mmHg]. The difference was more pronounced among patients with critical ischaemia compared with claudicants, and also more evident among diabetics. The error of oscillometric pressure determination in subjects with leg arterial disease inversely increased with CW Doppler ankle pressure. In 39% of the recordings in legs with a CW Doppler systolic pressure below 100 mmHg, the oscillometric mean arterial pressure was higher than the recorded CW Doppler systolic pressure. In conclusion, the oscillometric method to determine systolic ankle pressure, based on the concept of maximum cuff oscillations occurring near mean arterial pressure, is not reliable in leg arterial disease, usually overestimating ankle pressure.
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| 3. |
- Mustafa, S, et al.
(författare)
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Hyperthermia-induced vasoconstriction of the carotid artery and the role of potassium channels
- 2005
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Ingår i: Journal of Stroke & Cerebrovascular Diseases. - : Elsevier BV. - 1052-3057 .- 1532-8511. ; 14:3, s. 122-126
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Tidskriftsartikel (refereegranskat)abstract
- Clinical experience and experimental studies have shown that hyperthermia can cause cerebral ischaemia and brain damage. By in vitro experiments with heating, we previously were able to induce carotid artery constriction. The objective of the present study was to clarify the mechanism of this thermal response. Isometric tension was recorded in rabbit carotid artery specimens using organ baths during stepwise temperature elevation. The heating responses were investigated at basal tone, in precontracted vessels, after blocking of adrenergic responses and administration of potassium (K)-channel activators and inhibitors. Stepwise heating of carotid artery strips from 37°C to 47°C induced reproducible graded contraction. The hyperthermic responses were not due to adrenergic stimulation, which were reduced and resistant to neurogenic blockade by tetrodotoxin. Heating-induced contractions were potentiated by the K-channel inhibitors tetraethylammonium, BaCl2, charybdotoxin, and the Na+/K+ ATPase inhibitor ouabain. Levcromakalim (BRL), a K+-channel activator, reduced heating induced contractions. Heating of carotid artery preparations induced reversible graded vasoconstriction proportional to temperature. The heating-induced contractions were not mediated by an adrenergenic process, but rather were due to inhibition of K+ channels, which increases Ca2+ entry. In vivo, this reaction may lead to a disturbance of autoregulation of cerebral blood flow and ischemia with brain damage. © 2005 by National Stroke Association.
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| 4. |
- Tanaka, H, et al.
(författare)
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Blood pressure and cardiovascular autonomic function in healthy children and adolescents
- 2000
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Ingår i: Journal of Pediatrics. - : Elsevier BV. - 0022-3476 .- 1097-6833. ; 137:1, s. 63-67
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Tidskriftsartikel (refereegranskat)abstract
- Objectives: To investigate the relationship between blood pressure levels and cardiovascular autonomic function in adolescents and preadolescents. Study design: We measured variability of beat-to-beat arterial pressure and R-R intervals using power spectral analysis in 56 adolescents (aged 13-16 16 years, mean age, 9.0 +/- 1.4 years) and 71 preadolescents (6-12 years, mean age, 13.5 +/- 1.1 years) in the supine and standing positions. Results: Adolescents had higher levels of systolic arterial pressure and lower high-frequency power of RR intervals than preadolescents. Correlation between the basal level of arterial pressure and autonomic function rn as observed in adolescents but not in preadolescents. Tn adolescents, multivariate analysis indicated that tho basal level of arterial pressure was inversely related with the high-frequency power of RR intervals and positively with the ratio of low-frequency and high-frequency pow er. No significant relation was found in preadolescents. During standing, adolescents had a more marked increase in diastolic arterial pressure, heart rate, low frequency of R-R intervals, and low frequency of arterial pressure compared with those of preadolescents, Changes in diastolic pressure showed a significant negative correlation with changes in high frequency of R-R intervals. Conclusion: Cardiovascular autonomic function plays an important role in increasing blood pressure levels associated with increased modulation of vagal tone of the heart after puberty but does not in the preadolescent.
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| 5. |
- Tanaka, H., et al.
(författare)
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Evidence of decreased sympathetic function in children with psychosomatic symptoms
- 2002
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Ingår i: Clinical Autonomic Research. - : Springer Science and Business Media LLC. - 0959-9851 .- 1619-1560. ; 12:6, s. 477-482
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Tidskriftsartikel (refereegranskat)abstract
- We investigated cardiovascular autonomic function using power spectral analysis of heart rate variation and beat-to-beat finger arterial pressure at rest and while standing and correlated these findings with self-reported psychosomatic and psychosocial symptoms in 122 schoolchildren. Children with three or more psychosomatic and psychosocial symptoms (somatizers) were found to have significantly lower blood pressure than children without symptoms. Somatizers had the more decreased spectral power of the low frequency (LF) band of arterial pressure and RR intervals in the supine position. The high frequency (HF) power did not differ between the two groups. Somatizers showed a more marked reduction in systolic arterial pressure at the onset of standing than did subjects without symptoms but somatizers showed an identical response in systolic arterial pressure when compared to subjects without symptoms during the later stage of standing. The increases in the LF band of arterial pressure and LF/HF of RR intervals during standing were higher in somatizers. These results suggest that somatizers have decreased sympathetic modulation. We conclude that psychosomatic and psychosocial symptoms in children might be associated with low blood pressure and decreased sympathetic modulation.
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| 6. |
- Thulesius, Olav, 1930-, et al.
(författare)
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Human exposures to acrylamide are below the threshold for carcinogenesis
- 2004
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Ingår i: Human and Experimental Toxicology. - : Sage Publications. - 0960-3271 .- 1477-0903. ; 23:7, s. 357-358
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Tidskriftsartikel (refereegranskat)abstract
- Dose-response calculations for a threshold of carcinogenesis in animal studies do not support the notion that acrylamide (ACR) with the present status of consumption in food is carcinogenic for humans. This is in agreement with the recent reassuring epidemiological studies which have shown a lack of correlation between exposure to ACR in food and the incidence of cancer. © Arnold 2004.
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| 7. |
- Thulesius, Olav, 1930-
(författare)
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Phlebography and heparin for deep venous thrombosis introduced by Gunnar Bauer more than 60 years ago
- 2006
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Ingår i: Phlebology. - : SAGE Publications. - 0268-3555 .- 1758-1125. ; 21:3, s. 107-109
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Tidskriftsartikel (refereegranskat)abstract
- The story of a surgeon who in a country hospital in Sweden became a pioneer of modern phebology. He helped to set the standard of venography and heparin treatment for deep venous thrombosis and post-thrombotic valvular insufficiency more than 60 years ago. This happened when the surgeon Gunnar Bauer, stimulated by advancement in research and development of anticoagulants, introduced heparin treatment for deep venous thrombosis. He also started using descending phlebography for detection of venous reflux and advocated the controversial method of early ambulation after deep venous thrombosis. © 2006 Royal Society of Medicine Press.
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| 8. |
- Thulesius, Olav, 1930-
(författare)
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Thermal reactions of blood vessels in vascular stroke and heatstroke
- 2006
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Ingår i: Medical principles and practice. - : S. Karger AG. - 1011-7571 .- 1423-0151. ; 15:4, s. 316-321
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Tidskriftsartikel (refereegranskat)abstract
- Research on the pathophysiology and treatment of brain damage with special focus on thermal vascular responses is the subject of this minireview. Interruption of cerebral blood supply by vascular obstruction, temporary cardiac arrest or hyperthermia causes a sudden attack of vascular stroke or heatstroke with serious consequences. It may not induce immediate cell death, but can precipitate a complex biochemical cascade leading to a delayed neuronal loss. When testing thermal vasomotor responses by stepwise cooling of isolated carotid arteries, a temperature-proportional dilatation was observed while heating induced the opposite response: a marked vasoconstriction. General hyperthermia with an increased oxygen demand combined with a reduction of blood supply therefore is a serious consequence. At the cellular level an important mechanism involving hyperthermia is the temperature-dependent regulation of K+ channel tone of vascular smooth muscle. Further, their inhibition through temperature elevation causes vasoconstriction. In heatstroke, which can induce platelet aggregation and the release of the vasoconstrictor serotonin, arterial cooling attenuates this response. General hypothermia is induced to prevent or attenuate neurological damage in stroke. The procedure is not without serious side effects. Therefore, rapid institution of selective brain cooling has been considered in adults and in infants with postpartum encephalopathy. Copyright © 2006 S. Karger AG.
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| 9. |
- Thulesius, Olav, 1930-
(författare)
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Vensystemets fysiologi och patofysiologi
- 2002
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Ingår i: Klinisk fysiologisk kärldiagnostik. - Lund : Studentlitteratur AB. - 9789144021898 - 9144021895 ; , s. 245-254
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 10. |
- Yousif, MHM, et al.
(författare)
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A pharmacological study of bronchodilator properties of NKH477, forskolin, and beta-agonists on guinea pig and ovine isolated bronchioles
- 2000
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Ingår i: Drug development research (Print). - 0272-4391 .- 1098-2299. ; 51:3, s. 169-176
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Tidskriftsartikel (refereegranskat)abstract
- In this study we assessed the relaxant responses of two direct adenylate cyclase activators, NKH477 and forskolin, in comparison with two beta -adrenoceptor agonists, salbutamol and isoprenaline. The possible potentiation effect of NKH477 and forskolin on beta -agonist-induced bronchodilatation was examined. The effectiveness of NKH477 and forskolin in reversing tachyphylaxis development to salbutamol or isoprenaline was also investigated. We tested the in vitro bronchodilator effect of salbutamol, NKH477, and forskolin (10(-9)-10(-4) M) On isolated guinea pig bronchiolar ring segments precontracted with carbachol (3 muM). Salbutamol, NKH477, and forskolin produced a concentration-dependent relaxation. Potency values (pD(2)) were determined from cumulative concentration-response curves. The rank order for their potencies was salbutamol > NKH477 > forskolin (7.3 +/- 0.3, 6.4 +/- 0.3, and 5.4 +/- 0.1, respectively). The bronchodilator effects of salbutamol, isoprenaline, NKH477, and forskolin (10(-9)-10(-4) M) were examined on isolated ovine bronchioles precontracted with carbachol (0.3 muM). Isoprenaline, NKH477, and forskolin produced a concentration-dependent relaxation with pot values of 6.1 +/- 0.2, 5.4 +/- 0.2, and 5.3 +/- 0.2, respectively. Tachyphylaxis to the relaxant effects of salbutamol on guinea pig isolated bronchioles was experimentally induced and the potency of salbutamol was reduced to 5.9 +/- 0.2 after 24 h incubation with salbutamol (10(-5) M). NKH477 and forskolin (10(-6) M) produced a partial reversal of tachyphylaxis to salbutamol-induced relaxation using salbutamol pretreated tissues. The potency of salbutamol was increased to 6.6 +/- 0.2 and 5.9 +/- 0.2 after incubation with NKH477 or forskolin (10(-6) M), respectively Tachyphylaxis to the relaxant effects of isoprenaline resulted in a reduced potency of 5.7 +/- 0.2. Forskolin (10-6 M) Produced a partial reversal of tachyphylaxis, while NKH477 (10(-6) M) produced a complete reversal of tachyphylaxis to isoprenaline-induced relaxation with an pot value of 6.3 +/- 0.1. In conclusion, the guinea pig and sheep isolated bronchioles serve as good models to study the relaxant effects of the bronchodilator agents salbutamol, isoprenaline, NKH477, and forskolin. The beta -agonists examined had higher potencies than NKH477 or forskolin. However, the two adenylate cyclase activators, with greater effectiveness of NKH477, when used in combination with the beta -agonists, could produce an increase in the potency of the beta -agonists. Furthermore, the effectiveness of NKH477 and forskolin in reversing tachyphylaxis to the bronchodilator effects of the beta -agonists, particularly salbutamol, may provide an advantage in long-term use of beta -agonists in bronchial asthma therapy. Drug Dev. Res. 51:169-176, 2000. (C) 2001 Wiley-Liss, Inc.
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