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排序方式: 共有357条查询结果,搜索用时 31 毫秒
1.
Jan Willem R. Pott Kwok H. Wong 《Albrecht von Graefes Archiv fur klinische und experimentelle Ophthalmologie》2006,244(10):1357-1359
Background Leber’s hereditary optic neuropathy (LHON) is a maternally inherited optic neuropathy caused by mutations in mitochondrial DNA (mtDNA). It is also believed that several epigenetic factors have an influence on the development of LHON.Methods A case series was observed.Results Three patients who developed bilateral optic neuropathy are presented. All patients had a primary LHON mutation in their mtDNA, but also a subnormal vitamin B12 serum level at the time of presentation.Conclusions The clinical picture of optic neuropathy associated with vitamin B12 deficiency shows similarity to that of LHON. Both involve the nerve fibres of the papillomacular bundle. The present case reports suggest that optic neuropathy in patients carrying a primary LHON mtDNA mutation may be precipitated by vitamin B12 deficiency. Therefore, known carriers should take care to have an adequate dietary intake of vitamin B12 and malabsorption syndromes like those occurring in familial pernicious anaemia or after gastric surgery should be excluded. 相似文献
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F. Pott F. S. Larsen E. Ejlersen P. Linkis L. G. Jrgensen N. H. Secher 《Clinical physiology and functional imaging》1995,15(2):119-130
Summary. During transplantation of the liver cerebral perfusion was monitored by transcranial Doppler determined middle cerebral artery mean flow velocity (Vmean) and pulsatility index (PI) in six fulminant hepatic failure patients and 11 patients with chronic liver disease. In both groups of patients Vmean, PI and central haemodynamic variables were recorded during (1) the last preanhepatic hour; (2) the anhepatic phase; (3) the first 15 min of reperfusion; and (4) for the following 45 min of reperfusion. No significant differences were detected between the two groups of patients with respect to changes of variables with time. The Vmean (40±13 cm s-1 [mean±SD]), thoracic electrical impedance (TI) (30±7 Ohm), heart rate (97±19 beats min-1), mean arterial pressure (84±9 mmHg) and arterial carbon dioxide tension (PaCO2, 4.5±0.4 kPa) remained stable in the anhepatic phase, while cardiac output (CO, 7.6±2.7 to 5.4±1.41 min-1), stroke volume (SV, 79±26 to 56±15 ml) and PI (1.2±0.3 to 0.9±0.2) decreased (P<0.05). During reperfusion, CO (9.9±4.01 min-1), SV (105±40 ml), PaCO2 (5.5±0.6 kPa), Vmean (57±17 cm s-1) and PI (1.2±0.2) became elevated. Taken together, during the anhepatic phase of the liver transplantation a maintained central blood volume as indicated by the constant TI served for a stable blood pressure and in turn cerebral perfusion, whereas revascularization of the graft increased cerebral perfusion concomitant with an elevated carbon dioxide tension. 相似文献
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During orthostatic hypotension we evaluated whether presyncopal symptoms relate to a reduced brain oxygenation. Nine subjects performed 50° head-up tilt for 1 h and eight subjects were followed during 2 h of supine rest and during 1 h of 10° head-down tilt. Cerebral perfusion was assessed by transcranial Doppler determined middle cerebral artery blood velocity (MCA vmean), while brain blood oxygenation was assessed by near-infrared spectrophotometry determined concentration changes for oxygenated (ΔHbO2) and deoxygenated haemoglobin and brain cell oxygenation by the oxidized cytochrome c concentration (ΔCytO2). During head-up tilt, six volunteers developed presyncopal symptoms and mean arterial pressure (88 (78–103) to 68 (57–79) mmHg; median and range), heart rate (96 (72–111) to 65 (50–107) beats min?1), MCA vmean (59 (51–82) to 41 (29–56) cm s?1), ΔHbO2 (by ?5.3 (?3.0 to ?14.8) μmol l?1) and ΔCytO2 were reduced (by ?0.2 (?0.1 to ?0.4) μmol l?1; P < 0.05). During tilt down the cardiovascular variables recovered immediately and ΔHbO2 increased to 2.2 (?0.9–12.0) mmol L?1 above the resting value and also ΔCytO2 recovered. In the nonsyncopal head-up tilted subjects as in the controls, blood pressure, heart rate, MCA vmean and brain oxygenation indices remained stable. The results suggest that during orthostasis, presyncopal symptoms relate not only to cerebral hypoperfusion but also to reduced brain oxygenation. 相似文献
5.
Katrin Banach Moritz Bünemann Jörg Hüser Lutz Pott 《Pflügers Archiv : European journal of physiology》1993,423(3-4):245-250
L-type Ca2+ current (I
Ca) was measured in cultured atrial myocytes from hearts of adult guinea-pigs using whole-cell voltage clamp. Potentiation of I
Ca induced by -adrenergic stimulation (isoprenaline 2· 10–7 M) could be completely antagonized by diluted sera (1100 v/v). Half-maximal inhibition of -receptorstimulated I
Ca occurred at about 11000. Basal I
Ca was not affected by serum. Atropine in a concentration (10–6M) that completely antagonized the anti-adrenergic effect of acetylcholine (ACh, 2·10–6 M) did not interfere with the effect of serum. In cells dialysed with cyclic adenosine monophosphate (cAMP)-containing (10–4 M) pipette solution, potentiated I
Ca was insensitive to both ACh and serum. Preincubation of the myocytes with pertussis toxin almost completely abolished the anti-adrenergic effects of both ACh and serum. The potency of serum was not reduced by dialysis. It is concluded that serum contains a factor which, like ACh, inhibits -receptor-stimulated adenylyl cyclase via Giprotein.A preliminary report of this work has appeared in abstract form [11] 相似文献
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Middle cerebral artery blood velocity during exercise with beta-1 adrenergic and unilateral stellate ganglion blockade in humans 总被引:5,自引:0,他引:5
Ide K Boushel R Sørensen HM Fernandes A Cai Y Pott F Secher NH 《Acta physiologica Scandinavica》2000,170(1):33-38
A reduced ability to increase cardiac output (CO) during exercise limits blood flow by vasoconstriction even in active skeletal muscle. Such a flow limitation may also take place in the brain as an increase in the transcranial Doppler determined middle cerebral artery blood velocity (MCA V(mean)) is attenuated during cycling with beta-1 adrenergic blockade and in patients with heart insufficiency. We studied whether sympathetic blockade at the level of the neck (0.1% lidocaine; 8 mL; n=8) affects the attenuated exercise - MCA V(mean following cardio-selective beta-1 adrenergic blockade (0.15 mg kg(-1) metoprolol i.v.) during cycling. Cardiac output determined by indocyanine green dye dilution, heart rate (HR), mean arterial pressure (MAP) and MCA V(mean) were obtained during moderate intensity cycling before and after pharmacological intervention. During control cycling the right and left MCA V(mean) increased to the same extent (11.4 +/- 1.9 vs. 11.1 +/- 1.9 cm s(-1)). With the pharmacological intervention the exercise CO (10 +/- 1 vs. 12 +/- 1 L min(-1); n=5), HR (115 +/- 4 vs. 134 +/- 4 beats min(-1)) and delta MCA V(mean) (8.7 +/- 2.2 vs. 11.4 +/- 1.9 cm s(-1) were reduced, and MAP was increased (100 +/- 5 vs. 86 +/- 2 mmHg; P < 0.05). However, sympathetic blockade at the level of the neck eliminated the beta-1 blockade induced attenuation in delta MCA V(mean) (10.2 +/- 2.5 cm s(-1)). These results indicate that a reduced ability to increase CO during exercise limits blood flow to a vital organ like the brain and that this flow limitation is likely to be by way of the sympathetic nervous system. 相似文献
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