Search results for "Flow"
showing 10 items of 5185 documents
Biophysics of venous return from the brain from the perspective of the pathophysiology of chronic cerebrospinal venous insufficiency
2011
This article discusses the biophysical aspects of venous outflow from the brain in healthy individuals and in patients with chronic cerebrospinal venous insufficiency. Blood flows out of the brain differently, depending on body position. In the supine position it flows out mainly through internal jugular veins, while in the upright position it uses the vertebral veins. This phenomenon is probably not due to the active regulation of the flow but instead results from the collapse of jugular veins when the head is elevated. Such a collapse is associated with a significant increase in flow resistance, which leads to redirection of the flow towards the vertebral pathway. Theoretical calculations…
The Effects of Renal Denervation on Renal Hemodynamics and Renal Vasculature in a Porcine Model
2015
Rationale Recently, the efficacy of renal denervation (RDN) has been debated. It is discussed whether RDN is able to adequately target the renal nerves. Objective We aimed to investigate how effective RDN was by means of functional hemodynamic measurements and nerve damage on histology. Methods and Results We performed hemodynamic measurements in both renal arteries of healthy pigs using a Doppler flow and pressure wire. Subsequently unilateral denervation was performed, followed by repeated bilateral hemodynamic measurements. Pigs were terminated directly after RDN or were followed for 3 weeks or 3 months after the procedure. After termination, both treated and control arteries were prepar…
Ticlopidine in the Treatment of Multiple Atherosclerotic Arteriopathy: a Strain Gauge Plethysmography and Döppler Spectrum Analysis Evaluation
1987
The effect of ticlopidine was compared with flunarizine in patients with iliac–femoral and / or femoral–popliteal arteriosclerotic arteriopathy accompanied by lesions of the cervical arteries of no haemodynamic significance. In the lower limbs, plethysmography (strain gauge measurements) and Döppler ultrasonography integrated by spectral analysis of the cervical arteries showed qualitative and quantitative improvements of the regional haematic flow. Side-effects were negligible which suggests that ticlopidine is useful in the treatment of multiple arteriosclerotic arteriopathy.
Study of Cellular DIMA Content by Flow Cytometry in Primary Bladder Carcinomas
1992
A prospective study of cellular DNA content by flow cytometry was performed on a nonconsecutive series of 67 patients undergoing diagnostic and/or therapeutic transurethral resection for primary urothelial bladder carcinoma. DNA-aneuploidy was present in 82% of the cases (55/67), while multiclonality was found in 45% of the DNA-aneuploid cases (25/55). DNA-ploidy was much more strictly correlated with histological grading (p less than 0.005) than with papillary or non-papillary growth pattern (p less than 0.05) or T staging (p less than 0.05). Of 26 patients with a minimum follow-up of 24 months, 100% (6/6) of cases with DNA-diploid neoplasias showed no signs of disease relapse, versus 10% …
Correlation of skeletal muscle blood oxygenation level-dependent MRI and skin laser doppler flowmetry in patients with systemic sclerosis
2013
Purpose To investigate the origin of skeletal muscle BOLD MRI alterations in patients with systemic sclerosis (SSc) by correlating BOLD MRI T2* signal of calf muscles with microcirculatory blood flow of calf skin measured by laser Doppler flowmetry (LDF). Materials and Methods BOLD MRI (3T) and LDF measurements were performed in 12 consecutive SSc patients (6 women, 6 men; mean age 54.0 ± 10.0 years) and 12 healthy volunteers (4 men, 8 women; mean age 44.7 ± 13.1 years). For both modalities, the same cuff compression paradigm at mid-thigh level was used. LDF datasets were acquired using a PeriScan PIM II Imager (Perimed AB, Stockholm, Sweden) at the upper calf corresponding to the level of …
On the Number of Measurements Necessary to Assess Regional Cerebral Blood Flow by Local Laser Doppler Recordings: A Simulation Study with Data from 4…
1995
Laser Doppler fluxmetry may improve the monitoring of cortical blood flow in neurosurgical patients. So far, however, the variability of laser Doppler readings found in the cerebral cortex has prevented a consequent usage of the technique in clinical practice. The current report analyzes the regional variability of laser Doppler readings from experimental animals. Typical frequency histograms of observed flow values display non-Gaussian distributions. A simulation technique is used to assess the number of measuring sites required for valid estimates of regional cortical flow. From a total of 990 local flow measurements from 45 rabbits random samples of sizes between 5 and 100 were repeatedl…
Distribution of lymphocyte surface antigens in healthy neonates.
1994
Using flow cytometric analysis we investigated the distribution of major lymphocyte surface antigens in newborn infants. A total of 221 newborns entered the study, of whom 53 fullfilled our criteria of healthy mature neonates. Percentages of immunofluorescent-positive cells were as follows (median and range from 25th to 75th percentiles given): for CD1 3.8%; 2.3%–5.8%. CD2 60.9%; 52.4%–66.8%. CD3 57.5%; 50.5%–63.3%. TcRas 57.7%; 48.1%–60.0%. CD4 36.3%; 28.0%–42.6%. CD8 23.0%; 20.0%–27.4%. CD11a 56.3%; 46.3%–68.5%. CD19 12.1%; 8.6%–14.8%. CD20 10.9%; 8.4%–12.9%. CD25 2.6%; 2.1%–4.5%. CDw52 61.0%; 51.2%–76.1%. CD71 5.2%; 3.1%–9.3%. While the ranges for the percentage of immunofluorescent-posi…
Coronary venous therapy to improve microvascular dysfunction.
2021
The coronary circulation is a complex system in which vascular resistances are determined by an interplay of forces in at least three compartments: the epicardial, the microvascular, and the venous district. Cardiologists, and particularly interventional cardiologists, normallly place the focus of their attention on diseases of the epicardial coronary circulation as possible causes of coronary syndromes and neglect the importance of the other two compartments of coronary circulation. The study of the coronary microcirculation, an increasingly recognized source of ischemia, has long been disregarded, but is witnessing a revival since the (re-)introduction of diagnostic tools in the better eq…
Perfusion heterogeneity does not explain excess muscle oxygen uptake during variable intensity exercise
2010
Previous research investigating endurance sports from a physiological perspectivehas mainly used constant or graded exercise protocols, although the nature ofsports like cross-country skiing and road cycling leads to continuous variations inworkload. Current knowledge is thus limited as regards physiological responses tovariations in exercise intensity. Therefore, the overall objective of the present thesiswas to investigate cardiovascular and metabolic responses to fluctuations inexercise intensity during exercise. The thesis is based on four studies (Studies I-IV);the first two studies use a variable intensity protocol with cardiorespiratory andblood measurements during cycling (Study I) …
Muscle Free Fatty-Acid Uptake Associates to Mechanical Efficiency During Exercise in Humans
2018
Intrinsic factors related to muscle metabolism may explain the differences in mechanical efficiency (ME) during exercise. Therefore, this study aimed to investigate the relationship between muscle metabolism and ME. Totally 17 healthy recreationally active male participants were recruited and divided into efficient (EF; n = 8) and inefficient (IE; n = 9) groups, which were matched for age (mean ± SD 24 ± 2 vs. 23 ± 2 years), BMI (23 ± 1 vs. 23 ± 2 kg m−2), physical activity levels (3.4 ± 1.0 vs. 4.1 ± 1.0 sessions/week), and V˙O2peak (53 ± 3 vs. 52 ± 3 mL kg−1 min−1), respectively, but differed for ME at 45% of V˙O2peak intensity during submaximal bicycle ergometer test (EF 20.5 ± 3.5 vs. I…