WorldWideScience

Sample records for blood flow tissue

  1. Tissue blood flow mapping using laser technology

    Science.gov (United States)

    Wardell, Karin; Linden, Maria; Nilsson, Gert E.

    1995-03-01

    By the introduction of the laser Doppler perfusion imager (LDPI) the microvascular blood flow in a tissue area can be mapped by sequentially moving a laser beam over the tissue. The measurement is performed without touching the tissue and the captured perfusion values in the peripheral circulation are presented as a color-coded image. In the ordinary LDPI-set-up, 64 X 64 measurement sites cover an area in the range of about 10 - 150 cm2 depending on system settings. With a high resolution modification, recordings can be done on tissue areas as small as 1 cm2. This high resolution option has been assessed in animal models for the mapping of small vessels. To be able to record not only spatial but also temporal perfusion components of tissue blood flow, different local area scans (LAS) have been developed. These include single point recording as well as integration of either 2 X 2, 3 X 3, or 4 X 4 measurement sites. The laser beam is repeatedly moved in a quadratic pattern over the small tissue area of interest and the output value constitutes the average perfusion of all captured values within the actual region. For the evaluation, recordings were performed on healthy volunteers before and after application of a vasodilatating cream on the dorsal side of the hand.

  2. Generating New Blood Flow : Integrating Developmental Biology and Tissue Engineering

    NARCIS (Netherlands)

    Krenning, Guido; Moonen, Jan-Renier A. J.; van Luyn, Marja J. A.; Harmsen, Martin C.

    2008-01-01

    Vascular tissue engineering aims to restore blood flow by seeding artificial tubular scaffolds with endothelial and smooth muscle cells, thus creating bioartificial blood vessels. Herein, the progenitors of smooth muscle and endothelial cells hold great promise because they efficiently differentiate

  3. Intrinsic regulation of blood flow in adipose tissue

    DEFF Research Database (Denmark)

    Henriksen, O; Nielsen, Steen Levin; Paaske, W

    1976-01-01

    Previous studies on intact human subcutaneous tissue have shown, that blood flow remains constant during minor changes in perfusion pressure. This so-called autoregulatory response has not been demonstrable in isolated preparations of adipose tissue. In the present study on isolated, denervated...... vasoconstriction with pronounced flow reduction. These two reactions may be important for local regulation of blood flow in subcutaneous tissue during orthostatic changes in arterial and venous pressure. It is concluded that the response in adipose tissue to changes in arterial pressure (autoregulation), venous...... subcutaneous tissue in female rabbits only 2 of 12 expts. revealed an autoregulatory response during reduction in arterial perfusion pressure. Effluent blood flow from the tissue in the control state was 15.5 ml/100 g-min (S.D. 6.4, n = 12) corresponding to slight vasodilatation of the exposed tissue...

  4. Blood flow in healed and inflamed periodontal tissues of dogs

    Energy Technology Data Exchange (ETDEWEB)

    Hock, J.M.; Kim, S.

    1987-01-01

    The objectives of this study were to determine if increased blood flow associated with gingivitis would decrease following resolution of gingival inflammation in dogs with periodontitis; if increased blood flow in inflamed gingiva was associated with changes in the blood flow of alveolar bone, and if blood flow in gingiva and alveolar bone increased if periodontitis was reactivated by ligating teeth. Regional blood flow was measured in dogs with pre-existing periodontitis, using radioisotope-labelled, plastic microspheres. In the first experiment on 4 adult Beagle dogs, teeth in the left jaws were treated to resolve the periodontitis, while teeth in the right jaws were not treated. Gingival and bone blood flow were measured after 12 wk. Blood flow was significantly (p<0.05) lower in non-inflamed healed gingiva (32.1 +- 2.7 ml/min/100 g) than in inflamed gingiva (46.1 +- 5.3 ml/min/100 g). No differences in the blood flow of the alveolar bone underlying inflamed or non-inflamed gingiva were present. In the second experiment, the right mandibular teeth of 5 dogs were treated to resolve periodontitis while teeth in the other quadrants were ligated for 4, 10 or 12 wk. The duration of ligation did not alter blood flow. Gingival blood flow around ligated maxillary and mandibular teeth was comparable and approximately 54% higher than around non-ligated teeth (p<0.03). The difference in blood flow between gingiva with G.I.>1 and gingiva with G.I.<2 was significant (p<0.04). Blood flow in bone was not altered by changes in the inflammatory status of the overlying gingiva. The findings suggest that changes in blood flow associated with inflammation are reversible and that blood flow alveolar bone is regulated independently of gingival blood flow.

  5. Blood flow in healed and inflamed periodontal tissues of dogs

    International Nuclear Information System (INIS)

    The objectives of this study were to determine if increased blood flow associated with gingivitis would decrease following resolution of gingival inflammation in dogs with periodontitis; if increased blood flow in inflamed gingiva was associated with changes in the blood flow of alveolar bone, and if blood flow in gingiva and alveolar bone increased if periodontitis was reactivated by ligating teeth. Regional blood flow was measured in dogs with pre-existing periodontitis, using radioisotope-labelled, plastic microspheres. In the first experiment on 4 adult Beagle dogs, teeth in the left jaws were treated to resolve the periodontitis, while teeth in the right jaws were not treated. Gingival and bone blood flow were measured after 12 wk. Blood flow was significantly (p1 and gingiva with G.I.<2 was significant (p<0.04). Blood flow in bone was not altered by changes in the inflammatory status of the overlying gingiva. The findings suggest that changes in blood flow associated with inflammation are reversible and that blood flow alveolar bone is regulated independently of gingival blood flow. (author)

  6. Blood flow and oxygenation in peritendinous tissue and calf muscle during dynamic exercise in humans

    DEFF Research Database (Denmark)

    Boushel, R; Langberg, Henning; Green, Stefan Mathias;

    2000-01-01

    1. Circulation around tendons may act as a shunt for muscle during exercise. The perfusion and oxygenation of Achilles' peritendinous tissue was measured in parallel with that of calf muscle during exercise to determine (1) whether blood flow is restricted in peritendinous tissue during exercise......, and (2) whether blood flow is coupled to oxidative metabolism. 2. Seven individuals performed dynamic plantar flexion from 1 to 9 W. Radial artery and popliteal venous blood were sampled for O2, peritendinous blood flow was determined by 133Xe-washout, calf blood flow by plethysmography, cardiac output...... by dye dilution, arterial pressure by an arterial catheter-transducer, and muscle and peritendinous O2 saturation by spatially resolved spectroscopy (SRS). 3. Calf blood flow rose 20-fold with exercise, reaching 44 +/- 7 ml (100 g)-1 min-1 (mean +/- s.e.m. ) at 9 W, while Achilles' peritendinous flow...

  7. Adrenergically stimulated blood flow in brown adipose tissue is not dependent on thermogenesis.

    Science.gov (United States)

    Abreu-Vieira, Gustavo; Hagberg, Carolina E; Spalding, Kirsty L; Cannon, Barbara; Nedergaard, Jan

    2015-05-01

    Brown adipose tissue (BAT) thermogenesis relies on blood flow to be supplied with nutrients and oxygen and for the distribution of the generated heat to the rest of the body. Therefore, it is fundamental to understand the mechanisms by which blood flow is regulated and its relation to thermogenesis. Here, we present high-resolution laser-Doppler imaging (HR-LDR) as a novel method for noninvasive in vivo measurement of BAT blood flow in mice. Using HR-LDR, we found that norepinephrine stimulation increases BAT blood flow in a dose-dependent manner and that this response is profoundly modulated by environmental temperature acclimation. Surprisingly, we found that mice lacking uncoupling protein 1 (UCP1) have fully preserved BAT blood flow response to norepinephrine despite failing to perform thermogenesis. BAT blood flow was not directly correlated to systemic glycemia, but glucose injections could transiently increase tissue perfusion. Inguinal white adipose tissue, also known as a brite/beige adipose tissue, was also sensitive to cold acclimation and similarly increased blood flow in response to norepinephrine. In conclusion, using a novel noninvasive method to detect BAT perfusion, we demonstrate that adrenergically stimulated BAT blood flow is qualitatively and quantitatively fully independent of thermogenesis, and therefore, it is not a reliable parameter for the estimation of BAT activation and heat generation.

  8. Effect of spinal sympathetic blockade upon postural changes of blood flow in human peripheral tissues

    DEFF Research Database (Denmark)

    Skagen, K; Haxholdt, O; Henriksen, O;

    1982-01-01

    local nervous blockade was induced by Lidocaine in 133Xe labelled subcutaneous tissue on one side. During epidural blockade and tilt blood flow increased by 12% whereas blood flow decreased by 30% on the control side. Thus epidural blockade had no influence on the vasoconstrictor response...

  9. Blood flow and oxygenation in peritendinous tissue and calf muscle during dynamic exercise in humans

    DEFF Research Database (Denmark)

    Boushel, Robert Christopher; Langberg, H; Green, Sara Marie Ehrenreich;

    2000-01-01

    1. Circulation around tendons may act as a shunt for muscle during exercise. The perfusion and oxygenation of Achilles' peritendinous tissue was measured in parallel with that of calf muscle during exercise to determine (1) whether blood flow is restricted in peritendinous tissue during exercise...... with a rise in leg vascular conductance and microvascular haemoglobin volume, despite elevated systemic vascular resistance. 4. The parallel rise in calf muscle and peritendinous blood flow and fall in O2 saturation during exercise indicate that blood flow is coupled to oxidative metabolism in both tissue...... by dye dilution, arterial pressure by an arterial catheter-transducer, and muscle and peritendinous O2 saturation by spatially resolved spectroscopy (SRS). 3. Calf blood flow rose 20-fold with exercise, reaching 44 +/- 7 ml (100 g)-1 min-1 (mean +/- s.e.m. ) at 9 W, while Achilles' peritendinous flow...

  10. Diet-induced changes in subcutaneous adipose tissue blood flow in man

    DEFF Research Database (Denmark)

    Simonsen, L; Bülow, J; Astrup, A;

    1990-01-01

    The effect of a carbohydrate-rich meal on subcutaneous adipose tissue blood flow was studied with and without continuous i.v. infusion of propranolol in healthy volunteers. The subcutaneous adipose tissue blood flow was measured with the 133Xe washout method in three different locations...... it in the forearm. This indicates that the mechanism for the flow increase is elicited by a stimulation of vascular beta-adrenoceptors in the subcutaneous adipose tissue, since the beta-adrenoceptor inhibition did not affect the overall metabolic and hormonal responses to the meal.......: the forearm, the thigh and the abdomen. The subjects were given a meal consisting of white bread, jam, honey and apple juice (about 2300 kJ). The meal induced a twofold increase in blood flow in the examined tissues. Propranolol abolished the flow increase in the thigh and the abdomen and reduced...

  11. Exercise-induced increase in dog adipose tissue blood flow before and after denervation

    DEFF Research Database (Denmark)

    Bülow, J; Madsen, J

    1986-01-01

    Subcutaneous adipose tissue blood flow was examined during rest and exercise in the inguinal fat pads of four female dogs using the Xe wash-out technique. The experiments were performed before and after denervation of one of the pads. No difference between the resting flows in the two pads could...... be demonstrated either before or after denervation. The flow increased about two-fold on average from rest to exercise. This response was similar before and after denervation. It is concluded that direct sympathetic innervation is not involved in the regulation of adipose tissue blood flow during exercise....

  12. SELF-MIXING LASER-DOPPLER VELOCIMETRY OF LIQUID FLOW AND OF BLOOD PERFUSION IN TISSUE

    NARCIS (Netherlands)

    DEMUL, FFM; KOELINK, MH; WEIJERS, AL; GREVE, J; AARNOUDSE, JG; GRAAFF, R; DASSEL, ACM

    1992-01-01

    The velocimetry method of self-mixing, i.e., the feedback of Doppler-scattered light into the laser cavity, is used for the measurement of liquid flow and of blood perfusion in human tissue. The method is eIucidated by the registration of the blood perfusion of a finger under repeated occlusion of t

  13. Determination of cardiac output, tissue blood flow, volume and lipid content in Sprague-Dawley rats

    International Nuclear Information System (INIS)

    One critical aspect of physiologically-based pharmacokinetic (PBPK) model development is the choice of values for organ blood flows, cardiac output and tissue volumes for input into models. These values vary depending upon the strain, size, age, and sex of animal for which a PBPK model is being developed. Tissue blood flows, cardiac output, tissue volume, and lipid content were determined in male S-D rats, (350-375 g, N=8). A radiolabel microsphere method utilizing Scandium (46Sc), Tin (113Sn),and Gadolinium (153Gd) was used to determine blood flow. Each rat received 3 radiolabeled injections. After the third injection, animals were sacrificed, and radioactivity in each tissue was determined in a 3-channel gamma counter. Tissues sampled include brain, heart, kidneys, liver, lungs, spleen, pancreas, adrenals, stomach, intestines, colon, testis, bone and skeletal muscle. Cardiac output was 142 ml/min. Blood flow values for eliminating organs were 0.49 (liver), 16.52 (kidney), and 1.77 (lung) ml/min/g tissue. Tissues which had significantly increased blood flow during the dark cycle included femur, abdonimal fat, triceps brachii and abdominal muscles, stomach, spleen and lung. Dissectable fat, organ volume, and organ lipid content were determined in a separate group of rats (N= 8). Volume and lipid content were determined for the same tissues as blood flow. Body fat was 7.35% of bw and extractable lipid content of eliminating organs was 42.3 (liver), 43.4 (kidney), and 35.9 (lung) mg/g tissue. Precise measurements should improve the accuracy of PBPK model predictions, and therfore help in reducing uncertainites in risk assessment of volatile organics and other pollutnats

  14. Blood flow measurements in selected oral tissues in dogs using radiolabelled microspheres and rubidium-86

    International Nuclear Information System (INIS)

    Radiolabelled microspheres and 86Rb were used in dogs to measure oral tissue blood flow. The tissues studied were mandibular alveolar and basal bone, oral mucosa, gingiva, lip, tongue and soft tissue of hard palate. A suspension of 6 x 106 cerium-141 labelled microspheres, 15 + - 5 μm in diameter was injected into the left ventricle through an arterial catheter in 9 healthy adult dogs. Cardiovascular stability was assessed during the catheterization and injection of microspheres. Following the microsphere injection, 500 μCi of 86Rb was injected intravenously and the animal was killed within 60s. Blood flow measured using 86Rb was not significantly different (p > 0.05) from radiolabelled microsphere flow in mandibular basal bone, oral mucosa and gingiva, suggesting that in these oral tissues nutritional or capillary exchange flow is similar to total blood flow. In mandibular alveolar bone, lip, tongue and soft tissue of hard palate, however, 86Rb measurements were significantly greater (p 86Rb shows promise for continued studies of blood flow in healthy and pathological oral tissues. (author)

  15. Loss of autoregulation of blood flow in subcutaneous tissue in juvenile diabetes

    DEFF Research Database (Denmark)

    Henriksen, O; Kastrup, J; Parving, H H;

    1984-01-01

    and retinopathy. The blood flow remained constant in all normal subjects, when the arterial perfusion pressure was varied between 70 and 150 mm Hg. All diabetics had impaired or reduced autoregulation of the subcutaneous blood flow. The blood flow increased and decreased almost linearly with the changes...... in arterial perfusion pressure. The mechanism underlying the defect autoregulation of blood flow in diabetics is uncertain; possibilities include structural changes of the arterioles and/or alterations of local metabolic factors.......The autoregulation of blood flow in subcutaneous tissue was investigated at the level of the lateral malleolus by the local 133Xenon washout technique. We have investigated eight long-term insulin-dependent diabetics and seven healthy controls. All diabetics had moderate diabetic nephropathy...

  16. Blood Flow Versus Hematocrit in Optimization of Oxygen Transfer to Tissue During Fluid Resuscitation.

    Science.gov (United States)

    Siam, Jamal; Kadan, Marwa; Flaishon, Ron; Barnea, Ofer

    2015-12-01

    The effectiveness of fluid resuscitation regimens in hemorrhagic trauma is assessed based on its ability to increase oxygen concentration in tissue. Fluid resuscitation using both crystalloids and colloids fluids, creates a dilemma due to its opposing effects on oxygen transfer. It increases blood flow thereby augmenting oxygen transport but it also dilutes the blood simultaneously and reduces oxygen concentration thereby reducing oxygen transport. In this work we have studied these two opposing effects of fluid therapy on oxygen delivery to tissue. A mathematical model of oxygen diffusion from capillaries to tissue and its distribution in tissue was developed and integrated into a previously developed hemodynamic model. The capillary-tissue model was based on the Krogh structure. Compared to other models, fewer simplifying assumptions were made leading to different boundary conditions and less constraints, especially regarding capillary oxygen content at its venous end. Results showed that oxygen content in blood is the dominant factor in oxygen transport to tissue and its effect is greater than the effect of flow. The integration of the capillary/tissue model with the hemodynamic model that links administered fluids with flow and blood dilution indicated that fluid resuscitation may reduce oxygen transport to tissue.

  17. Sympathetic reflex control of blood flow in human peripheral tissues

    DEFF Research Database (Denmark)

    Henriksen, O

    1991-01-01

    Sympathetic vasoconstrictor reflexes are essential for the maintenance of arterial blood pressure in upright position. It has been generally believed that supraspinal sympathetic vasoconstrictor reflexes elicited by changes in baroreceptor activity play an important role. Recent studies on human ...... to collision of normodromically and antidromically conducted impulses in efferent sympathetic vasoconstrictor fibers. The evidence obtained suggests that sympathetic vasoconstrictor reflexes to postural changes are complex and highly differentiated....

  18. Insulin action in muscle and adipose tissue in type 2diabetes: The significance of blood flow

    Institute of Scientific and Technical Information of China (English)

    2015-01-01

    Under normal metabolic conditions insulin stimulatesmicrovascular perfusion (capillary recruitment) ofskeletal muscle and subcutaneous adipose tissue andthus increases blood flow mainly after meal ingestionor physical exercise. This helps the delivery of insulinitself but also that of substrates and of other signallingmolecules to multiple tissues beds and facilitatesglucose disposal and lipid kinetics. This effect is impairedin insulin resistance and type 2 diabetes early in thedevelopment of metabolic dysregulation and reflectsearly-onset endothelial dysfunction. Failure of insulinto increase muscle and adipose tissue blood flowresults in decreased glucose handling. In fat depots, ablunted postprandial blood flow response will result inan insufficient suppression of lipolysis and an increasedspill over of fatty acids in the circulation, leading toa more pronounced insulin resistant state in skeletalmuscle. This defect in blood flow response is apparenteven in the prediabetic state, implying that it is afacet of insulin resistance and exists long before overthyperglycaemia develops. The following review intendsto summarize the contribution of blood flow impairmentto the development of the atherogenic dysglycemia anddyslipidaemia.

  19. Blood flow, substrate utilization and heat generation in tissues drained by the azygos vein in man.

    Science.gov (United States)

    Brundin, T; Hagenfeldt, L; Söderberg, R; Wahren, J

    1987-12-01

    The present study was undertaken to examine the blood flow, heat generation and substrate utilization in tissues drained by the azygos vein in healthy subjects. Catheters were inserted percutaneously into the azygos vein and the pulmonary artery in 10 healthy male subjects in the basal, post-absorptive state. Blood flow in the azygos vein was measured by thermodilution technique, blood temperature was recorded in both the azygos vein and the pulmonary artery and blood samples for the determination of oxygen content and substrate concentrations were collected from both vessels repeatedly at timed intervals. Free fatty acid (FFA) exchange was evaluated following the intravenous infusion of 14-C labelled oleic acid. The average azygos vein blood flow was 94 +/- 10 ml/min. The coefficient of variation for the flow determination was 3.6%. The blood temperature in the azygos vein was consistently higher than that in the pulmonary artery, indicating an average calculated net heat production in the tissues of 0.5 W. The oxygen uptake to the tissues drained by the azygos vein amounted to 6 +/- 1 ml/min. Significant amounts of glucose, FFA and ketone bodies were taken up in the azygos area, while both glycerol and FFA were released. The FFA uptake could, if oxidized, account for about half of the oxygen uptake. In conclusion, the findings indicate that, in the basal state, the tissues drained by the azygos vein utilize both glucose and FFA. Heat is generated within the area but the rate of generation is low and can largely be explained by the oxidative metabolism. The findings do not support an important role for brown adipose tissue metabolism in the interscapular region in man. PMID:3427881

  20. Interscapular brown adipose tissue blood flow in the rat. Determination with 133xenon clearance compared to the microsphere method

    DEFF Research Database (Denmark)

    Astrup, A; Bülow, J; Madsen, J

    1984-01-01

    a close correlation to the blood flow values determined with microspheres. Y = 0.98. X + 0.15 (r = 0.96, P less than 0.001). The Xe clearance method has the advantages compared to the microsphere technique that it permits continuous monitoring of the blood flow and does not require the sacrifice......The xenon clearance method was adapted to continuous measurement of interscapular brown adipose tissue (ISBAT) blood flow in anesthetized rats. The ISBAT-blood partition coefficient for xenon was determined to 3.6 ml X g-1. The blood flow values obtained by Xe clearance were compared with flow...

  1. Subcutaneous adipose tissue blood flow in the forefoot during 24 hours. Labeling pattern and reproducibility

    DEFF Research Database (Denmark)

    Jelnes, Rolf; Bülow, J; Tønnesen, K H

    1987-01-01

    Wash-out of 133xenon from a local depot in the subcutaneous adipose tissue in the forefoot was measured continuously during 24 hours on subsequent recordings in 51 feet (normal circulation: 10, intermittent claudication: 22 and ischaemic nocturnal rest pain: 19) with a mean time interval of 26 days...... (range: 3-90 days). The patients were studied under two different conditions. Firstly, during the day in the erect position, awake (sitting, standing and quiet walking) and secondly, during night hours in the supine position, asleep. The coefficient of variation of nocturnal adipose tissue blood flow...

  2. Deuterium MR spectroscopy at 4.7 T. Quantification of tumour and subcutaneous tissue blood flow in animal models

    DEFF Research Database (Denmark)

    Wirestam, R; Larsen, V.A.; Stubgaard, M;

    1995-01-01

    Deuterium MR spectroscopy was used for the determination of tissue blood flow (TBF). The tracer D2O was injected into the tissue of interest, and tracer washout was followed using a 4.7 T spectroscopy/imaging unit. Normal subcutaneous tissue in rats was studied, as well as tissue influenced by...

  3. Effects of terlipressin on patients with sepsis via improving tissue blood flow.

    Science.gov (United States)

    Xiao, Xudong; Zhang, Jie; Wang, Yaoli; Zhou, Jian; Zhu, Yu; Jiang, Dongpo; Liu, Liangming; Li, Tao

    2016-01-01

    Terlipressin (TP), an analog of arginine vasopressin, was reported beneficial in sepsis patients when combined use with norepinephrine (NE), but the undetermined action, mechanism, and safety limited it to become the first-line vasopressor for sepsis patients. With 32 septic shock patients, we investigated the effects of a small dose of TP (1.3 μg/kg/h) on hemodynamic, tissue blood flow, vital organ function, acid-base balance, and coagulation function to systemically know the beneficial effect and side effects of TP on septic shock. The results showed that as compared with the single use of NE group (17 patients), a small dose of TP (1.3 μg/kg/h) in combination with NE continuous infusion, except for decreasing the mortality and NE requirement, could better improve and stabilize the hemodynamics, improve the tissue blood flow, increase the blood oxygen saturation and urine volume, and decrease the lactate level and complication rate (47% versus 82.3% in NE group). Meanwhile, TP + NE did not induce blood bilirubin increase and platelet count decrease and hyponatremia that vasopressin has. The results show that low dose of TP continuous infusion can help NE achieve the good resuscitation effect by improving tissue blood flow, stabilizing hemodynamics, and protecting organ function in septic shock patients while did not induce the side effects that high dose or bonus of TP or vasopressin induced. Low dose of TP may be recommended as the first-line vasopressor for refractory hypotension after severe sepsis or septic shock. PMID:26253455

  4. Noncontact diffuse optical assessment of blood flow changes in head and neck free tissue transfer flaps

    Science.gov (United States)

    Huang, Chong; Radabaugh, Jeffrey P.; Aouad, Rony K.; Lin, Yu; Gal, Thomas J.; Patel, Amit B.; Valentino, Joseph; Shang, Yu; Yu, Guoqiang

    2015-07-01

    Knowledge of tissue blood flow (BF) changes after free tissue transfer may enable surgeons to predict the failure of flap thrombosis at an early stage. This study used our recently developed noncontact diffuse correlation spectroscopy to monitor dynamic BF changes in free flaps without getting in contact with the targeted tissue. Eight free flaps were elevated in patients with head and neck cancer; one of the flaps failed. Multiple BF measurements probing the transferred tissue were performed during and post the surgical operation. Postoperative BF values were normalized to the intraoperative baselines (assigning "1") for the calculation of relative BF change (rBF). The rBF changes over the seven successful flaps were 1.89±0.15, 2.26±0.13, and 2.43±0.13 (mean±standard error), respectively, on postoperative days 2, 4, and 7. These postoperative values were significantly higher than the intraoperative baseline values (pflap vascularity after the tissue transfer. By contrast, rBF changes observed from the unsuccessful flaps were 1.14 and 1.34, respectively, on postoperative days 2 and 4, indicating less flow recovery. Measurement of BF recovery after flap anastomosis holds the potential to act early to salvage ischemic flaps.

  5. [Effect of hyperbaric oxygenation on local tissue blood flow to a small intestine transplant intended for esophagoplasty].

    Science.gov (United States)

    Vinnitskiĭ, L I; Piuskiulian, L I; Zhidkov, I L; Demurov, E A

    1981-04-01

    The time course of the local tissue blood flow in the small intestinal graft used for esophagoplasty was studied in 54 acute experiments on rabbits exposed to hyperbaric oxygenation (1 hour, 2 ata). It has been shown that hyperbaric oxygenation prevents alterations in the local tissue blood flow in the small intestine. This fact provides evidence in favour of hyperbaric oxygenation application under clinical conditions.

  6. Diet-induced changes in subcutaneous adipose tissue blood flow in man: effect of beta-adrenoceptor inhibition

    DEFF Research Database (Denmark)

    Simonsen, L; Bülow, J; Astrup, A;

    1990-01-01

    The effect of a carbohydrate-rich meal on subcutaneous adipose tissue blood flow was studied with and without continuous i.v. infusion of propranolol in healthy volunteers. The subcutaneous adipose tissue blood flow was measured with the 133Xe washout method in three different locations......: the forearm, the thigh and the abdomen. The subjects were given a meal consisting of white bread, jam, honey and apple juice (about 2300 kJ). The meal induced a twofold increase in blood flow in the examined tissues. Propranolol abolished the flow increase in the thigh and the abdomen and reduced...... it in the forearm. This indicates that the mechanism for the flow increase is elicited by a stimulation of vascular beta-adrenoceptors in the subcutaneous adipose tissue, since the beta-adrenoceptor inhibition did not affect the overall metabolic and hormonal responses to the meal....

  7. Evaluation of a new high power, wide separation laser Doppler probe : Potential measurement of deeper tissue blood flow

    NARCIS (Netherlands)

    Clough, Geraldine; Chipperfield, Andrew; Byrne, Christopher; de Mul, Frits; Gush, Rodney

    2009-01-01

    Objective: To compare the output from a novel high power, wide separation laser Doppler flow probe (DP1-V2-HP, 4 mm, with IRLD20) with that of a standard flow probe (DP1-V2, 0.5 mm, with DRT4) (Moor UK) and to explore its potential for use in the noninvasive measurement of blood flow in deeper tissu

  8. Do distribution volumes and clearances relate to tissue volumes and blood flows? A computer simulation

    Directory of Open Access Journals (Sweden)

    Lemmens Hendrikus JM

    2006-06-01

    Full Text Available Abstract Background Kinetics of inhaled agents are often described by physiological models. However, many pharmacokinetic concepts, such as context-sensitive half-times, have been developed for drugs described by classical compartmental models. We derived classical compartmental models that describe the course of the alveolar concentrations (FA generated by the physiological uptake and distribution models used by the Gas Man® program, and describe how distribution volumes and clearances relate to tissue volumes and blood flows. Methods Gas Man® was used to generate FA vs. time curves during the wash-in and wash-out period of 115 min each with a high fresh gas flow (8 L.min-1, a constant alveolar minute ventilation (4 L.min-1, and a constant inspired concentration (FI of halothane (0.75%, isoflurane (1.15%, sevoflurane (2%, or desflurane (6%. With each of these FI, simulations were ran for a 70 kg patient with 5 different cardiac outputs (CO (2, 3, 5, 8 and 10 L.min-1 and for 5 patients with different weights (40, 55, 70, 85, and 100 kg but the same CO (5 L.min-1. Two and three compartmental models were fitted to FA of the individual 9 runs using NONMEM. After testing for parsimony, goodness of fit was evaluated using median prediction error (MDPE and median absolute prediction error (MDAPE. The model was tested prospectively for a virtual 62 kg patient with a cardiac output of 4.5 L.min-1 for three different durations (wash-in and wash-out period of 10, 60, and 180 min each with an FI of 1.5% halothane, 1.5% isoflurane, sevoflurane 4%, or desflurane 12%. Results A three-compartment model fitted the data best (MDPE = 0% and MDAPE ≤ 0.074% and performed equally well when tested prospectively (MDPE ≤ 0.51% and MDAPE ≤ 1.51%. The relationship between CO and body weight and the distribution volumes and clearances is complex. Conclusion The kinetics of anesthetic gases can be adequately described e by a mammilary compartmental model. Therefore

  9. Are blood flow and lipolysis in subcutaneous adipose tissue influenced by contractions in adjacent muscles in humans?

    DEFF Research Database (Denmark)

    Stallknecht, Bente; Dela, Flemming; Helge, Jørn Wulff

    2006-01-01

    Aerobic exercise increases whole body adipose tissue lipolysis, but is lipolysis higher in subcutaneous adipose tissue (SCAT) adjacent to contracting muscles than in SCAT adjacent to resting muscles? Ten healthy, overnight-fasted males performed one-legged knee extension exercise at 25% of maximal......(-1), P > 0.05; 85% W(max) 88 +/- 31 vs. -9 +/- 25 nmol x 100 g(-1) x min(-1), P contracting than adjacent to resting muscle irrespective of exercise intensity. Thus specific exercises can induce "spot lipolysis...... from femoral SCAT interstitial and arterial glycerol concentrations and blood flow. In general, blood flow and lipolysis were higher in femoral SCAT adjacent to contracting than adjacent to resting muscle (time 15-30 min; blood flow: 25% W(max) 6.6 +/- 1.0 vs. 3.9 +/- 0.8 ml x 100 g(-1) x min(-1), P...

  10. Assessment of tissue blood flow following small artery welding with an intraluminal dissolvable stent.

    Science.gov (United States)

    He, F C; Wei, L P; Lanzetta, M; Owen, E R

    1999-01-01

    Using the technique of radioactive 51Cr-labeled biological microspheres, this study evaluated arterial blood flow following small vessel anastomosis by CO2 laser welding and a dissolvable stent in the lumen. A total of 30 Sprague-Dawley rats were divided into two groups. Group A: 11 rats had their femoral arteries ligated on one side. The contralateral side served as a control, with the artery transected and repaired using conventional microsuturing. Group B: 19 rats had their femoral arteries transected and repaired using CO2 laser welding and an intraluminal dissolvable stent technique. The contralateral side was again used as a control using conventional microsuturing. At 1 hr postoperatively, 51Cr-labeled biological microspheres were injected centripetally into the left common carotid artery and the legs and thighs immediately harvested for measurement of radioactivity. All repaired arteries were patent (30/30 in the microsuturing group and 19/19 in the stented welding group), with no detectable stenosis or dilation at the repaired site. Statistical analysis showed that tissue radioactivity (cpm/g) in the ligated group (3,972 +/- 384 in thighs and 3,142 +/- 742 in legs) was significantly lower than in the microsuturing group (7,132 +/- 1,723 in thighs and 6,557 +/- 1,469 in legs) (P welding group, in both thighs (7,064 +/- 2,599 and 7,006 +/- 2,406, respectively; P > 0.05) and legs (6,386 +/- 1,703 and 6,288 +/- 1,757, respectively; P > 0.05). This study provided evidence that the dissolvable stent placed intraluminally does not impair blood circulation and that when coupled with CO2 laser welding offers a high-quality alternative to conventional small vessel anastomosis. PMID:10231124

  11. The role of tissue oxygen tension in the control of local blood flow in the microcirculation of skeletal muscles

    DEFF Research Database (Denmark)

    Ngo, Thuc Anh

    2010-01-01

    In the microcirculation blood flow is highly regulated dependent on the metabolic activity of the tissues. Among several mechanisms, mechanisms involved in the coupling of changes in tissue oxygen tension due to changes in the metabolic activity of the tissue play an important role. In the systemic...... (inhibitor of KATP channels) in the superfusate abolished both vasodilatation and constriction to low and high oxygen superfusate, indicating that KATP channels are involved in both hypoxic vasodilatation and hyperoxic vasoconstriction. Red blood cells (RBCs) have been proposed to release ATP and...... as in the intact blood-perfused arteriole. This indicates that RBCs are not essential for hypoxic vasodilatation. In addition several potential pathways were evaluated. Application of DPCPX (inhibitor of adenosine A1 and A2 receptors) and L-NAME (inhibitor of NO-synthase) did not affect vasomotor responses to low...

  12. Regional disturbances in blood flow and metabolism in equine limb wound healing with formation of exuberant granulation tissue

    DEFF Research Database (Denmark)

    Sørensen, Mette A.; Petersen, Lars; Bundgaard, Louise;

    2014-01-01

    As in other fibroproliferative disorders, hypoxia has been suggested to play a key role in the pathogenesis of exuberant granulation tissue (EGT). The purpose of this study was to investigate metabolism and blood flow locally in full-thickness wounds healing with (limb wounds) and without (body...... a significant difference between body and limb wounds. In conclusion, the metabolic disturbances may suggest an inadequate oxygen supply during the wound healing process in equine limb wounds healing with EGT. This may be related to the inherently decreased perfusion in the wound bed of limb wounds....... wounds) formation of EGT. Microdialysis was used to recover endogenous metabolites from the wounds, and laser Doppler flowmetry was used to measure blood flow. Measurements were performed before wounding and 1-28 days after wounding. Blood flow was consistently lower in limb wounds than in body wounds...

  13. Blood flow and vascular reactivity in collaterally perfused brain tissue. Evidence of an ischemic penumbra in patients with acute stroke

    DEFF Research Database (Denmark)

    Olsen, T S; Larsen, B; Herning, M;

    1983-01-01

    In a group of 48 patients with completed stroke, 8 patients had viable collaterally perfused brain tissue which was accessible for rCBF recordings with a two dimensional technique. All 8 had deep subcortical infarcts on CT-scan, and angiographic occlusion of the arteries normally supplying the in...... the experimental finding of an ischemic penumbra associated with acute cerebral infarcts and suggest that early restoration of the blood flow in acute stroke patients might improve recovery and prognosis in selected patients....

  14. Determination of adipose tissue blood flow with local 133Xe clearance. Evaluation of a new labelling technique

    DEFF Research Database (Denmark)

    Simonsen, Lene; Enevoldsen, Lotte Hahn; Bülow, Jens

    2003-01-01

    Adipose tissue blood flow was measured in six healthy, non-obese subjects with the xenon wash-out technique after labelling of the tissue by either injection of 133Xe dissolved in isotonic sodium chloride (water depot) or injection of 133Xe in gas form (gas depot). The wash-out rates were...... registered from four depots simultaneously. Two depots were placed above the umbilicus, and two depots were placed below the umbilicus in the abdominal, subcutaneous adipose tissue. A water depot and a gas depot were placed in the two positions, respectively. It was not possible to demonstrate any difference...... between the wash-out rates registered from the two depot types, and it was also not possible to demonstrate any difference between the changes in wash-out rates induced by an oral glucose load. Similarly, the tissue distribution of the water and the gas depots appeared to be similar as registered...

  15. Regional blood flow in brain and peripheral tissues during acute experimental arterial subdural bleeding.

    Science.gov (United States)

    Orlin, J R; Zwetnow, N N; Hall, C

    1993-01-01

    The effects of a large intracranial arterial subdural bleeding on regional blood flow in the brain (rCBF) and in other body organs were studied, using a porcine model. The bleeding was produced by leading blood through a catheter from the abdominal aorta via an electronic drop recorder into the subdural compartment (SDC) over the left cerebral hemisphere. Pressures in the right lateral cerebral ventricle and in the cisterna magna were recorded along with 15 other vital parameters. Measurements of rCBF were carried out using radioactive microspheres 1) before the start of bleeding, 2) during the early bleeding phase, and 3) during the late bleeding phase. When the bleeding was initiated, the intracranial pressures rose within one minute to a level approximately 40 mmHg below the systemic arterial pressure, whilst the latter usually decreased 30-40 mmHg. In the subsequent early bleeding phase the cerebral perfusion pressure and the bleeding pressure fluctuated at a level of approximately 40 mmHg for several minutes. In the late bleeding phase, the perfusion pressure decreased maximally, even when a Cushing reaction was activated. During the early bleeding phase the changes in rCBF varied between the cerebral regions. However, the mean flow remained largely constant in the presence of a decreasing cerebrovascular resistance, indicating that autoregulation of CBF was intact. Concomitantly, cardiac output and heart rate decreased, whilst regional blood flow in extracerebral organs tended to increase, possibly due to an intracranial effect on the autonomic nervous system. In the late bleeding phase, rCBF was critically reduced in all regions, in spite of a marked rise in systemic arterial pressure.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8372718

  16. Noncontact diffuse optical assessment of blood flow changes in head and neck free tissue transfer flaps (Conference Presentation)

    Science.gov (United States)

    Huang, Chong; Radabaugh, Jeffrey P.; Aouad, Rony K.; Lin, Yu; Gal, Thomas J.; Patel, Amit B.; Valentino, Joseph; Shang, Yu; Yu, Guoqiang

    2016-02-01

    Head and neck cancer accounts for 3 to 5% of all cancers in the United States. Primary or salvage surgeries are extensive and often lead to major head and neck defects that require complex reconstructions with local, regional, or free tissue transfer flaps. Knowledge of tissue blood flow (BF) changes after free tissue transfer may enable surgeons to predict the failure of flap thrombosis at an early stage. This study used our recently developed noncontact diffuse correlation spectroscopy to monitor dynamic BF changes in free flaps without getting in contact with the targeted tissue. Eight free flaps were elevated in patients with head and neck cancer; one of the flaps failed. Multiple BF measurements probing the transferred tissue were performed during and post the surgical operation. Postoperative BF values were normalized to the intraoperative baselines (assigning '1') for the calculation of relative BF change (rBF). The rBF changes over the seven successful flaps were 1.89 +/- 0.15, 2.26 +/- 0.13, and 2.43 +/- 0.13 (mean +/- standard error) respectively on postoperative days 2, 4, and 7. These postoperative values were significantly higher than the intraoperative baseline values (p flap vascularity after the tissue transfer. By contrast, rBF changes observed from the unsuccessful flap were 1.14 and 1.34 respectively on postoperative days 2 and 4, indicating a less flow recovery. Measurement of BF recovery after flap anastomosis holds the potential to act early to salvage ischemic flaps.

  17. New optical sensing technique of tissue viability and blood flow based on nanophotonic iterative multi-plane reflectance measurements

    Directory of Open Access Journals (Sweden)

    Yariv I

    2016-10-01

    Full Text Available Inbar Yariv,1 Menashe Haddad,2,3 Hamootal Duadi,1 Menachem Motiei,1 Dror Fixler1 1Faculty of Engineering and the Institute of Nanotechnology and Advanced Materials, Bar Ilan University, Ramat Gan, Israel; 2Sackler School of Medicine, Tel-Aviv University, Tel-Aviv, Israel; 3Mayanei Hayeshua Medical Center, Benei Brak, Israel Abstract: Physiological substances pose a challenge for researchers since their optical properties change constantly according to their physiological state. Examination of those substances noninvasively can be achieved by different optical methods with high sensitivity. Our research suggests the application of a novel noninvasive nanophotonics technique, ie, iterative multi-plane optical property extraction (IMOPE based on reflectance measurements, for tissue viability examination and gold nanorods (GNRs and blood flow detection. The IMOPE model combines an experimental setup designed for recording light intensity images with the multi-plane iterative Gerchberg-Saxton algorithm for reconstructing the reemitted light phase and calculating its standard deviation (STD. Changes in tissue composition affect its optical properties which results in changes in the light phase that can be measured by its STD. We have demonstrated this new concept of correlating the light phase STD and the optical properties of a substance, using transmission measurements only. This paper presents, for the first time, reflectance based IMOPE tissue viability examination, producing a decrease in the computed STD for older tissues, as well as investigating their organic material absorption capability. Finally, differentiation of the femoral vein from adjacent tissues using GNRs and the detection of their presence within blood circulation and tissues are also presented with high sensitivity (better than computed tomography to low quantities of GNRs (<3 mg. Keywords: Gerchberg-Saxton, optical properties, gold nanorods, blood vessel, tissue viability

  18. Evaluation of copper(II)-pyruvaldehyde bis (N-4-methylthiosemicarbazone) for tissue blood flow measurement using a trapped tracer model

    International Nuclear Information System (INIS)

    We have investigated the application of a simple trapped tracer model to measurements of tissue 64Cu-PTSM uptake combined with continuous arterial sampling. A dual-tracer method was used to compare blood flow estimated by 64Cu-PTSM with values derived from measurements using cobalt-57 microspheres in the rat. Prolonged retention of 64Cu-PTSM following intravenous administration was initially confirmed in both normal tissues and tumours. After intraventricular 64Cu-PTSM infusion, cumulative arterial 64Cu activity increased progressively, and after extraction in n-octanol was found to plateau to levels corresponding with those reached following administration of 57Co microspheres. Rapid and species-dependent rates of 64Cu-PTSM decomposition to non-extractable 64Cu complexes were found in rat and human blood in vitro (70% ± 6% and 43% ± 5% respectively at 16 min), demonstrating the need for immediate processing of arterial samples. Close agreement was found between blood flow estimated by 64Cu-PTSM and 57Co microsphere methods in tissues of low to moderate flow: muscle (0.01, 0.08, 0.07 ml/min per gram; mean difference, mean 64Cu, mean 57Co), brain (0.09, 0.52, 0.43 ml/min per gram) and kidney (-0.16, 2.29, 2.45 ml/min per gram). Estimates of cardiac output also compared favourably between the two methods (5.7, 59.8, 54.1 ml/min). (orig./MG)

  19. Impaired autoregulation of blood flow in subcutaneous tissue of long-term type 1 (insulin-dependent) diabetic patients with microangiopathy

    DEFF Research Database (Denmark)

    Kastrup, J; Nørgaard, T; Parving, H H;

    1985-01-01

    Autoregulation of blood flow in subcutaneous tissue was studied at the level of the lateral malleolus in eight long-term Type 1 (insulin-dependent) diabetic patients with clinical microangiopathy, eight short-term Type 1 diabetic patients without clinical microangiopathy and seven healthy control...... by activation of the leg muscle vein pump (heel raising). Mean arterial blood pressure was thus varied between 60 and 160 mmHg. In normal and short-term diabetic subjects blood flow remained within 10% of control values during the changes in arterial blood pressure. In six of the eight Type 1 diabetic patients...... with clinical microangiopathy, autoregulation of blood flow was impaired, blood flow changing approximately 20% per 10 mmHg change in arterial blood pressure; the slope of the autoregulation curves was significantly higher compared with the two control groups (p less than 0.02). Resting mean arterial blood...

  20. Cerebral tissue oxygenation index and superior vena cava blood flow in the very low birth weight infant.

    LENUS (Irish Health Repository)

    Moran, M

    2012-02-01

    BACKGROUND: Superior vena cava (SVC) flow assesses blood flow from the upper body, including the brain. Near infrared spectroscopy (NIRS) provides information on brain perfusion and oxygenation. AIM: To assess the relationship between cerebral tissue oxygenation index (cTOI) and cardiac output measures in the very low birth weight (VLBW) infant in the first day of life. METHODS: A prospective observational cohort study. Neonates with birth weight less than 1500 g (VLBW) were eligible for enrollment. Newborns with congenital heart disease, major congenital malformations and greater than Papile grade1 Intraventricular Haemorrhage on day 1 of life were excluded. Echocardiographic evaluation of SVC flow was performed in the first 24 h of life. Low SVC flow states were defined as a flow less than 40 mL\\/kg\\/min. cTOI was measured using NIRO 200 Hamamatsu. RESULTS: Twenty-seven VLBW neonates had both echocardiography and NIRS performed. The median (range) gestation was 29\\/40 (25 + 3 to 31 + 5 weeks) and median birth weight was 1.2 kg (0.57-1.48 kg). The mean (SD) TOI was 68.1 (7.9)%. The mean (SD) SVC flow was 70.36(39.5) mLs\\/kg\\/min. The correlation coefficient of cerebral tissue oxygenation and SVC flow was r = 0.53, p-value 0.005. There was a poor correlation between right and left ventricular output and cTOI which is not surprising considering the influence of intra- and extracardiac shunts. CONCLUSION: There is a positive relationship between cerebral TOI values and SVC flow in the very low birth infant on day one of life.

  1. Blood flow responses to mild-intensity exercise in ectopic vs. orthotopic prostate tumors; dependence upon host tissue hemodynamics and vascular reactivity.

    Science.gov (United States)

    Garcia, Emmanuel; Becker, Veronika G C; McCullough, Danielle J; Stabley, John N; Gittemeier, Elizabeth M; Opoku-Acheampong, Alexander B; Sieman, Dietmar W; Behnke, Bradley J

    2016-07-01

    Given the critical role of tumor O2 delivery in patient prognosis and the rise in preclinical exercise oncology studies, we investigated tumor and host tissue blood flow at rest and during exercise as well as vascular reactivity using a rat prostate cancer model grown in two transplantation sites. In male COP/CrCrl rats, blood flow (via radiolabeled microspheres) to prostate tumors [R3327-MatLyLu cells injected in the left flank (ectopic) or ventral prostate (orthotopic)] and host tissue was measured at rest and during a bout of mild-intensity exercise. α-Adrenergic vasoconstriction to norepinephrine (NE: 10(-9) to 10(-4) M) was determined in arterioles perforating the tumors and host tissue. To determine host tissue exercise hyperemia in healthy tissue, a sham-operated group was included. Blood flow was lower at rest and during exercise in ectopic tumors and host tissue (subcutaneous adipose) vs. the orthotopic tumor and host tissue (prostate). During exercise, blood flow to the ectopic tumor significantly decreased by 25 ± 5% (SE), whereas flow to the orthotopic tumor increased by 181 ± 30%. Maximal vasoconstriction to NE was not different between arterioles from either tumor location. However, there was a significantly higher peak vasoconstriction to NE in subcutaneous adipose arterioles (92 ± 7%) vs. prostate arterioles (55 ± 7%). Establishment of the tumor did not alter host tissue blood flow from either location at rest or during exercise. These data demonstrate that blood flow in tumors is dependent on host tissue hemodynamics and that the location of the tumor may critically affect how exercise impacts the tumor microenvironment and treatment outcomes. PMID:27125846

  2. The effect of non-esterified long-chain fatty acids on blood flow and thermogenesis in brown adipose tissue in the young dog

    DEFF Research Database (Denmark)

    Astrup, A; Bülow, J; Christensen, N J

    1985-01-01

    In vitro experiments have demonstrated that increasing the molar ratio of extracellular non-esterified fatty acids (NEFA) to albumin stimulates thermogenesis in brown adipocytes. To test these results, in vivo blood flow and local temperature were measured in perirenal brown adipose tissue (BAT) ...

  3. A Decrease in Spatially Resolved Near-Infrared Spectroscopy-Determined Frontal Lobe Tissue Oxygenation by Phenylephrine Reflects Reduced Skin Blood Flow

    DEFF Research Database (Denmark)

    Ogoh, Shigehiko; Sato, Kohei; Okazaki, Kazunobu;

    2014-01-01

    BACKGROUND: Spatially resolved near-infrared spectroscopy-determined frontal lobe tissue oxygenation (ScO2) is reduced with administration of phenylephrine, while cerebral blood flow may remain unaffected. We hypothesized that extracranial vasoconstriction explains the effect of phenylephrine on Sc...

  4. Acute effects of nicotine and smoking on blood flow, tissue oxygen, and aerobe metabolism of the skin and subcutis

    DEFF Research Database (Denmark)

    Sørensen, Lars Tue; Jørgensen, Stig; Petersen, Lars J;

    2009-01-01

    BACKGROUND: Nicotine released from tobacco smoke causing reduction in blood flow has been suggested as causative for postoperative wound complications in smokers, but the mechanism remains unknown. MATERIALS AND METHODS: In eight healthy male smokers and eight ex-smokers, the cutaneous and subcut......BACKGROUND: Nicotine released from tobacco smoke causing reduction in blood flow has been suggested as causative for postoperative wound complications in smokers, but the mechanism remains unknown. MATERIALS AND METHODS: In eight healthy male smokers and eight ex-smokers, the cutaneous...

  5. Deuterium Nuclear Magnetic Resonance Measurements of Blood Flow and Tissue Perfusion Employing 2H2O as a Freely Diffusible Tracer

    Science.gov (United States)

    Ackerman, Joseph J. H.; Ewy, Coleen S.; Becker, Nancy N.; Shalwitz, Robert A.

    1987-06-01

    The use of deuterium oxide (2H2O) is proposed as a freely diffusible nuclear magnetic resonance (NMR) blood flow and tissue perfusion tracer of potential clinical utility. Deuterium is a stable, nonradiative isotope commercially available as 2H2O at enrichment levels of essentially 100%--i.e., 110 molar equivalent deuterium. This high concentration, together with the short relaxation time of the spin 1 (quadrupole) deuterium nuclide, provides substantial sensitivity for NMR spectroscopy. As a result, when 2H2O is administered in a bolus fashion to a specific tissue or organ in vivo, the deuterium NMR intensity time course can be analyzed, using mathematical models developed by others for radiolabeled tracers, to measure the rate of blood flow and tissue perfusion. Such an application is demonstrated herein at a static magnetic field of 8.5 tesla. Using single-compartment flow modeling, hepatic blood flow and tissue perfusion in fasted (18 hr) male Sprague-Dawley rats was determined to be 61 ± 17 (mean ± SD) ml/100 g per min (n = 5).

  6. Effect of short-term scrotal hyperthermia on spermatological parameters, testicular blood flow and gonadal tissue in dogs

    NARCIS (Netherlands)

    Henning, H; Masal, C; Herr, A; Wolf, K; Urhausen, C; Beineke, A; Beyerbach, M; Kramer, S; Günzel-Apel, A-R

    2014-01-01

    The objective was to assess the effect of a short-term scrotal hyperthermia in dogs on quantitative and qualitative ejaculate parameters, testicular blood flow and testicular and epididymal histology. After a control period, the scrotum of seven normospermic adult beagle dogs was insulated with a se

  7. Cyclo-oxygenase-2 mediated prostaglandin release regulates blood flow in connective tissue during mechanical loading in humans

    DEFF Research Database (Denmark)

    Langberg, H; Boushel, Robert Christopher; Skovgaard, D;

    2003-01-01

    prior to the experiment) or COX unspecific (n = 8, indomethacin 100 mg (12 and 1 h pre-experiment) and acetyl salicylic acid 500 mg day-1 for 3 days pre-experiment). Prostaglandin E2 (PGE2) concentration was determined by microdialysis and blood flow by 133Xe washout. In C, interstitial PGE2 rose from...

  8. Correlation between regional cerebral blood flow and degree of brain tissue injury of interictal epileptic activity in patients with epilepsy

    International Nuclear Information System (INIS)

    Objective: To explore the correlation between the change of regional cerebral blood flow (rCBF) and brain tissue injury from interictal epileptic activity in patients with epilepsy. Methods: Forty-eight patients with epilepsy and 30 healthy persons were included in the study from which the serum S100β protein levels were determined by double antibody sandwich ELISA method. SPECT rCBF imaging was performed in all patients. The visual and semi-quantitative analyses were used to analyze the epileptic foci. SPSS 11.0 was applied for variance and linear correlation analyses. Results: Serum S-100β in patients with interictal epileptic activity was significantly higher than that in control group ((0.572±0.163) μg/L vs (0.218±0.134) μg/L, t =9.96, P<0.01). According to epilepsy control criteria, 20 cases achieved complete control (CC), 18 cases achieved partial control (PR). However, 10 cases got no improvement,whose serum S-100β protein ((0.809±0.056) μg/L) and the percentage change of rCBF ((0.337±0.060) %) were significantly higher than those of CC ((0.443±0.083) μg/L, (0.035±0.038) %) and those of PC ((0.585±0.108) μg/L, (0.187±0.075)%), F=56. 740, 92. 316, P<0.01. There were high correlation between serum S-100β and the percentage change of rCBF in epilepsy patients (r =0.887, P<0.01). Conclusion: Serum S-100β protein assay combined with rCBF on SPECT imaging can make semi-quantitative diagnosis of epilepsy and help evaluate the brain damage from interictal epileptic activity. (authors)

  9. Blood Flow Multiscale Phenomena

    OpenAIRE

    Agić, Ante; Mijović, Budimir; Nikolić, Tatjana

    2007-01-01

    The cardiovascular disease is one of most frequent cause deaths in modern society. The objective of this work is analyse the effect of dynamic vascular geometry (curvature, torsion,bifurcation) and pulsatile blood nature on secondary flow, wall shear stress and platelet deposition. The problem was examined as multi-scale physical phenomena using perturbation analysis and numerical modelling. The secondary flow determined as influence pulsatile pressure, vascular tube time-dependen...

  10. Microwave Ablation Using Four-Tine Antenna: Effects of Blood Flow Velocity, Vessel Location, and Total Displacement on Porous Hepatic Cancer Tissue

    Science.gov (United States)

    Chaichanyut, Montree

    2016-01-01

    This research is concerned with microwave ablation analyses using a 2.45 GHz four-tine (4T) antenna for hepatic cancer tissue. In the study, three-dimensional finite-element models were utilized to examine the tissue temperature distributions during and after MW ablation. A preliminary study was first carried out with regard to the specific absorption rates along the 4T antenna insertion depths and the temperature distributions inside the solid and porous liver models with either 3 cm-in-diameter tumor or 5 cm-in-diameter tumor. Based on the preliminary results, the porous models were further examined for the effect of varying blood flow velocities (0–200 cm/s) with a 1 cm-in-diameter blood vessel next to the antenna and also for the effect of vessel-antenna locations (0, 0.8, and 1.3 cm) with a constant blood flow velocity of 16.7 cm/s. All scenarios were simulated under temperature-controlled mode (90°C). The findings revealed that the blood flow velocity and vessel location influence the ablation effectiveness and that increased blood flow inhibits heat transfer to the vessel wall. At the nearest and farthest vessel-antenna locations (0 and 1.3 cm), approximately 90.3% and 99.55% of the cancer cells were eradicated except for the areas adjacent to the vessel. In addition, total tissue thermal displacement is 5.9 mm which is 6.59% of the total length of the overall model. PMID:27642364

  11. Microwave Ablation Using Four-Tine Antenna: Effects of Blood Flow Velocity, Vessel Location, and Total Displacement on Porous Hepatic Cancer Tissue.

    Science.gov (United States)

    Chaichanyut, Montree; Tungjitkusolmun, Supan

    2016-01-01

    This research is concerned with microwave ablation analyses using a 2.45 GHz four-tine (4T) antenna for hepatic cancer tissue. In the study, three-dimensional finite-element models were utilized to examine the tissue temperature distributions during and after MW ablation. A preliminary study was first carried out with regard to the specific absorption rates along the 4T antenna insertion depths and the temperature distributions inside the solid and porous liver models with either 3 cm-in-diameter tumor or 5 cm-in-diameter tumor. Based on the preliminary results, the porous models were further examined for the effect of varying blood flow velocities (0-200 cm/s) with a 1 cm-in-diameter blood vessel next to the antenna and also for the effect of vessel-antenna locations (0, 0.8, and 1.3 cm) with a constant blood flow velocity of 16.7 cm/s. All scenarios were simulated under temperature-controlled mode (90°C). The findings revealed that the blood flow velocity and vessel location influence the ablation effectiveness and that increased blood flow inhibits heat transfer to the vessel wall. At the nearest and farthest vessel-antenna locations (0 and 1.3 cm), approximately 90.3% and 99.55% of the cancer cells were eradicated except for the areas adjacent to the vessel. In addition, total tissue thermal displacement is 5.9 mm which is 6.59% of the total length of the overall model. PMID:27642364

  12. Effect of steel and teflon infusion catheters on subcutaneous adipose tissue blood flow and infusion counter pressure in humans

    DEFF Research Database (Denmark)

    Højbjerre, Lise; Skov-Jensen, Camilla; Kaastrup, Peter;

    2009-01-01

    BACKGROUND: Subcutaneous tissue is an important target for drug deposition or infusion. A local trauma may induce alterations in local microcirculation and diffusion barriers with consequences for drug bioavailability. We examined the influence of infusion catheters' wear time on local...... microcirculation and infusion counter pressure. METHODS: One steel catheter and one Teflon (Dupont, Wilmington, DE) catheter were inserted in subcutaneous, abdominal adipose tissue (SCAAT) in 10 healthy, lean men. The catheters were infused with isotonic saline at a rate of 10 microL/h for 48 h. Another steel...... catheter and a Teflon catheter were inserted contralateral to the previous catheters after 48 h. The infusion counter pressure was measured during a basal infusion rate followed by a bolus infusion. The measurements during a basal rate infusion were repeated after the bolus infusion. Adipose tissue blood...

  13. Real-time evaluation of tissue vitality by monitoring of microcirculatory blood flow, HbO2, and mitochondrial NADH redox state

    Science.gov (United States)

    Deutsch, Assaf; Pevzner, Eliyahu; Jaronkin, Alex; Mayevsky, Avraham

    2004-06-01

    Monitoring of tissue vitality (oxygen supply/demand) in real time is very rare in clinical practice although its use as an early warning alarming system, for clinical care medicine, is very practical. In our previous communication (SPIE 2003) we described the Tissue Spectroscope - TiSpec02, by which tissue microcirculatory blood flow (TBF) and mitochondrial NADH fluorescence were measured using a single light source (390nm). In order to improve the measurement capabilities as well as to decrease dramatically the size and cost of this clinical device, we have changed the TiSpec02 into a multi-wavelength illumination system in the new TiSpec03. In order to measure microcirculatory blood flow by laser Doppler flowmetry we used a 785nm laser diode. For mitochondrial NADH fluorescence measurement we adopted the 370nm LED. For the determination of the oxygenation level of hemoglobin (HbO2) we used the 2-wavelength reflectance technique. This new monitored parameter that was added to the TiSpec03 increases the accuracy of the diagnosis of tissue vitality. The bundle of optical fibers used to connect the tissue to the TiSpec03, was integrated into a special anchoring methodology depending on the monitored tissue or organ. In order to test the performance of the improved TiSpec we have used it in experimental animals brain models exposed to various pathophysiological conditions. Rats and gerbils were anesthetized and the fiber optic probe was located epidurally used dental acrylic cement. During anoxia and ischemia the lack of O2 led to a clear decrease in TBF and HbO2 while NADH shows a large elevation. When brain activation was induced by cortical spreading depression (SD), the elevated O2 consumption was recorded as a large oxidation (decrease) of mitochondrial NADH while TBF increase dramatically. Blood HbO2 was not affected significantly by the SD wave.

  14. Effect of insulin catheter wear-time on subcutaneous adipose tissue blood flow and insulin absorption in humans

    DEFF Research Database (Denmark)

    Clausen, Trine Schnedler; Kaastrup, Peter; Stallknecht, Bente

    2009-01-01

    blood flow (ATBF) and absorption of the rapid-acting insulin analog insulin aspart over a period of 4 days. METHODS: Teflon insulin catheters (Medtronic, Minneapolis, MN) were inserted into the abdominal SAT of 10 healthy men without diabetes (mean +/- SEM age, 23.0 +/- 1.1 years; body mass index, 22...... +/- 3 min on day 0 to 45 +/- 4 min on day 4 (P = 0.019). Neither peak plasma concentration nor area under the curve of insulin aspart changed significantly. CONCLUSIONS: Insertion of a Teflon insulin catheter into the SAT results in increased ATBF and faster absorption of insulin aspart in a period of 4...

  15. Blood flow autoregulation in pedicled flaps

    DEFF Research Database (Denmark)

    Bonde, Christian T; Holstein-Rathlou, Niels-Henrik; Elberg, Jens J

    2009-01-01

    INTRODUCTION: Clinical work on the blood perfusion in skin and muscle flaps has suggested that some degree of blood flow autoregulation exists in such flaps. An autoregulatory mechanism would enable the flap to protect itself from changes in the perfusion pressure. The purpose of the present study...... was to evaluate if, and to what extent, a tissue flap could compensate a reduction in blood flow due to an acute constriction of the feed artery. Further, we wanted to examine the possible role of smooth muscle L-type calcium channels in the autoregulatory mechanism by pharmacological intervention with the L......-type calcium channel blocker nimodipine and the vasodilator papaverine. MATERIAL AND METHODS: Pedicled flaps were raised in pigs. Flow in the pedicle was reduced by constriction of the feed artery (n=34). A transit time flow probe measured the effect on blood flow continuously. Following this, three different...

  16. Local Control of Blood Flow

    Science.gov (United States)

    Clifford, Philip S.

    2011-01-01

    Organ blood flow is determined by perfusion pressure and vasomotor tone in the resistance vessels of the organ. Local factors that regulate vasomotor tone include myogenic and metabolic autoregulation, flow-mediated and conducted responses, and vasoactive substances released from red blood cells. The relative importance of each of these factors…

  17. Subtracted dynamic MR perfusion source images (sMRP-SI) provide collateral blood flow assessment in MCA occlusions and predict tissue fate

    Energy Technology Data Exchange (ETDEWEB)

    Villringer, Kersten; Serrano-Sandoval, Rafael; Galinovic, Ivana; Ostwaldt, Ann-Christin; Brunecker, Peter; Fiebach, Jochen B. [Charite-Universitaetsmedizin, Academic Neuroradiology, Center for Stroke Research (CSB), Berlin (Germany); Grittner, Ulrike [Charite, Universitaetsmedizin Berlin, Center for Stroke Research, Berlin (Germany); Charite, Department for Biostatistics and Clinical Epidemiology, Berlin (Germany); Schneider, Alice [Charite, Universitaetsmedizin Berlin, Center for Stroke Research, Berlin (Germany); Rocco, Andrea [Charite, Department of Neurology and Center for Stroke Research, Berlin (Germany)

    2016-05-15

    Collateral blood flow is accepted as a predictive factor of tissue fate in ischemic stroke. Thus, we aimed to evaluate a new method derived from MR perfusion source images to assess collateral flow in patients with ICA/MCA occlusions. A total of 132 patients of the prospective 1000+ study were examined. MR perfusion source images were assessed according to Δimg{sub n} = img{sub n} + 1 - img{sub n} - 1 using the five-grade Higashida collateral flow rating system. Higashida scores were correlated to mismatch (MM) volume, mismatch ratio, day 6 FLAIR lesion volumes and day 90 mRS. Patients with Higashida scores 3 and 4 had significantly lower admission NIHSS, smaller FLAIR day 6 lesion volumes (p < 0.001) and higher rates of better long-term outcome (mRS 0-2, p = 0.002). There was a linear trend for the association of Higashida grade 1 (p = 0.002) and 2 (p = 0.001) with unfavourable outcome (day 90 mRS 3-6), but no significant association was found for MM volume, MM ratio and day 90 mRS. Inter-rater agreement was 0.58 (95 % CI 0.43-0.73) on day 1, 0.70 (95 % CI 0.58-0.81) on day 2. sMRP-SI Higashida score offers a non-invasive collateral vessel and tissue perfusion assessment of ischemic tissue. The predictive value of Higashida rating proved superior to MM with regard to day 90 mRS. (orig.)

  18. Subtracted dynamic MR perfusion source images (sMRP-SI) provide collateral blood flow assessment in MCA occlusions and predict tissue fate

    International Nuclear Information System (INIS)

    Collateral blood flow is accepted as a predictive factor of tissue fate in ischemic stroke. Thus, we aimed to evaluate a new method derived from MR perfusion source images to assess collateral flow in patients with ICA/MCA occlusions. A total of 132 patients of the prospective 1000+ study were examined. MR perfusion source images were assessed according to Δimgn = imgn + 1 - imgn - 1 using the five-grade Higashida collateral flow rating system. Higashida scores were correlated to mismatch (MM) volume, mismatch ratio, day 6 FLAIR lesion volumes and day 90 mRS. Patients with Higashida scores 3 and 4 had significantly lower admission NIHSS, smaller FLAIR day 6 lesion volumes (p < 0.001) and higher rates of better long-term outcome (mRS 0-2, p = 0.002). There was a linear trend for the association of Higashida grade 1 (p = 0.002) and 2 (p = 0.001) with unfavourable outcome (day 90 mRS 3-6), but no significant association was found for MM volume, MM ratio and day 90 mRS. Inter-rater agreement was 0.58 (95 % CI 0.43-0.73) on day 1, 0.70 (95 % CI 0.58-0.81) on day 2. sMRP-SI Higashida score offers a non-invasive collateral vessel and tissue perfusion assessment of ischemic tissue. The predictive value of Higashida rating proved superior to MM with regard to day 90 mRS. (orig.)

  19. Regional cerebral blood flow in various types of brain tumor. Effect of the space-occupying lesion on blood flow in brain tissue close to and remote from tumor site

    DEFF Research Database (Denmark)

    Kuroda, K; Skyhøj Olsen, T; Lassen, N A

    1982-01-01

    Regional cerebral blood flow (rCBF) was measured in 23 patients with brain tumors using the 133Xe intra-carotid injection method and a 254 channel gamma camera. The glioblastomas (4) and astrocytomas (4) all showed hyperemia in the tumor and tumor-near region. This was also seen in several...

  20. Synthetic aperture tissue and flow ultrasound imaging

    DEFF Research Database (Denmark)

    Nikolov, Svetoslav

    at every emission, which makes it possible to average over a large number of lines. This makes stationary echo canceling easier and significantly improves the velocity estimates. Only 8 emissions per plane are necessary to create the color flow map. Scanning 12 cm in depth, up to 800 planes can be obtained...... imaging applied to medical ultrasound. It is divided into two major parts: tissue and blood flow imaging. Tissue imaging using synthetic aperture algorithms has been investigated for about two decades, but has not been implemented in medical scanners yet. Among the other reasons, the conventional scanning...... and beamformation methods are adequate for the imaging modalities in clinical use - the B-mode imaging of tissue structures, and the color mapping of blood flow. The acquisition time, however, is too long, and these methods fail to perform real-time three-dimensional scans. The synthetic transmit aperture...

  1. Endovascular blood flow measurement system

    Science.gov (United States)

    Khe, A. K.; Cherevko, A. A.; Chupakhin, A. P.; Krivoshapkin, A. L.; Orlov, K. Yu

    2016-06-01

    In this paper an endovascular measurement system used for intraoperative cerebral blood flow monitoring is described. The system is based on a Volcano ComboMap Pressure and Flow System extended with analogue-to-digital converter and PC laptop. A series of measurements performed in patients with cerebrovascular pathologies allows us to introduce “velocity-pressure” and “flow rate-energy flow rate” diagrams as important characteristics of the blood flow. The measurement system presented here can be used as an additional instrument in neurosurgery for assessment and monitoring of the operation procedure. Clinical data obtained with the system are used for construction of mathematical models and patient-specific simulations. The monitoring of the blood flow parameters during endovascular interventions was approved by the Ethics Committee at the Meshalkin Novosibirsk Research Institute of Circulation Pathology and included in certain surgical protocols for pre-, intra- and postoperative examinations.

  2. Blood flow in the choriocapillaris

    OpenAIRE

    Zouache, M. A.; Eames, I; Luthert, P J

    2015-01-01

    The choriocapillaris is a capillary bed located in a thin layer adjacent to the outer retina and is part of the oxygen delivery system to the photoreceptors of the eye. The blood flow is approximately planar and is serviced by microvessels, which join the choriocapillaris through inlets perpendicular to its plane. Capillaries are densely organised and separated by avascular septal posts, which direct the blood flow. The capillary bed is composed of a juxtaposition of tessellating vascular uni...

  3. Super-resolution spectral estimation of optical micro-angiography for quantifying blood flow within microcirculatory tissue beds in vivo

    OpenAIRE

    Yousefi, Siavash; Qin, Jia; Wang, Ruikang K.

    2013-01-01

    In this paper, we propose a super-resolution spectral estimation technique to quantify microvascular hemodynamics using optical microangiography (OMAG) based on optical coherence tomography (OCT). The proposed OMAG technique uses both amplitude and phase information of the OCT signals which makes it sensitive to the axial and transverse flows. The scanning protocol for the proposed method is identical to three-dimensional ultrahigh sensitive OMAG, and is applicable for in vivo measurements. I...

  4. Hyperhomocysteinemia decreases bone blood flow

    Directory of Open Access Journals (Sweden)

    Neetu T

    2011-01-01

    Full Text Available Neetu Tyagi*, Thomas P Vacek*, John T Fleming, Jonathan C Vacek, Suresh C TyagiDepartment of Physiology and Biophysics, School of Medicine, University of Louisville, Louisville, KY, USA *These authors have equal authorshipAbstract: Elevated plasma levels of homocysteine (Hcy, known as hyperhomocysteinemia (HHcy, are associated with osteoporosis. A decrease in bone blood flow is a potential cause of compromised bone mechanical properties. Therefore, we hypothesized that HHcy decreases bone blood flow and biomechanical properties. To test this hypothesis, male Sprague–Dawley rats were treated with Hcy (0.67 g/L in drinking water for 8 weeks. Age-matched rats served as controls. At the end of the treatment period, the rats were anesthetized. Blood samples were collected from experimental or control rats. Biochemical turnover markers (body weight, Hcy, vitamin B12, and folate were measured. Systolic blood pressure was measured from the right carotid artery. Tibia blood flow was measured by laser Doppler flow probe. The results indicated that Hcy levels were significantly higher in the Hcy-treated group than in control rats, whereas vitamin B12 levels were lower in the Hcy-treated group compared with control rats. There was no significant difference in folate concentration and blood pressure in Hcy-treated versus control rats. The tibial blood flow index of the control group was significantly higher (0.78 ± 0.09 flow unit compared with the Hcy-treated group (0.51 ± 0.09. The tibial mass was 1.1 ± 0.1 g in the control group and 0.9 ± 0.1 in the Hcy-treated group. The tibia bone density was unchanged in Hcy-treated rats. These results suggest that Hcy causes a reduction in bone blood flow, which contributes to compromised bone biomechanical properties.Keywords: homocysteine, tibia, bone density

  5. Phosphorothioate oligonucleotide inhibits tissue factor expression in endothelial cells induced by blood flow shear stress in rats

    Institute of Scientific and Technical Information of China (English)

    Li Qianning; Yang Yimin; Ying Dajun; Cheng Rongchuan; Gong Zili; Liu Yong; Zhou Zhujuan; Zheng Jian

    2008-01-01

    Objective: To determine the effect of antiparallel phosphorothioate triplex-forming oligonucleotide (apsTFO),which was designed according to shear stress response element (SSRE) in tissue factor (TF) gene promoter region, on the expression of endothelial TF in carotid artery stenosis rats. Methods: Rat model of severe carotid artery stenosis were inflicted by silica gel tube ligation. Half an hour before the model infliction, GT20-apsTFO, GT20-psTFO and GT21-apsTFO labeled with green fluorescence (FITC) were injected into the vena caudalis of rat at a dose of 0.5 mg/kg.Half an hour, 4 or 9 h after the ligation, the distribution of TFO in the common carotid artery, the liver and the kidney was detected with aid of fluorescence microscopy. And the mRNA and protein expressions of TF, Egr-1 and Spl in the above-mentioned organs were determined with in situ hybridization and immunohistoehemical assay respectively in 6 h after the model establishment, and the results were analyzed with an image analysis system. Results: Only in 1 h after TFO injection, fluorescent granules appeared in the liver, the kidney and the vascular wall and lumen of carotid artery,and then in 4.5 h, they still deposited in above sites except the vascular lumen. GT20-apsTFO and GT21-apsTFO significant down-regulated the mRNA and protein expressions of TF compared to the rats without treatment (P0.05).The 3 TFOs had no inhibition on the mRNA and protein expressions of Egr-I and Spl. Conclusion: Pretreated apsTFO can partly come into the vascular endothelial cells, and inhibit TF expression induced by shear stress, but had no effect on Egr-1 and Spl gene expressions.

  6. Development of a Phantom Tissue for Blood Perfusion Measurements and Noninvasive Blood Perfusion Estimation in Living Tissue

    OpenAIRE

    Mudaliar, Ashvinikumar

    2007-01-01

    A convenient method for testing and calibrating surface perfusion sensors has been developed. A phantom tissue model is used to mimic the non-directional blood flow of tissue perfusion. A computational fluid dynamics (CFD) model was constructed in Fluent to design the phantom tissue and validate the experimental results. The phantom perfusion system was used with a perfusion sensor based on the clearance of thermal energy. A heat flux gage measures the heat flux response of tissue whe...

  7. Effects of antiglaucoma drugs on blood supply to eye tissues

    Energy Technology Data Exchange (ETDEWEB)

    Chiou, G.C.Y.; Yan, H.Y.

    1986-03-01

    Although it is essential that intraocular pressure (IOP) be reduced in glaucoma treatment, it is also vitally important to provide sufficient blood flow to eye tissues so that healthy visual field is maintained. It is possible for an agent to reduce IOP and blood supply to the eye. In that case, glaucoma appears to be under control since IOP has been reduced to within normal range yet the disease is actually progressing, causing damage to the retina, optic nerve, and other tissues. /sup 85/Sr-Microsphere technique was used to study the effects of several antiglaucoma drugs on blood supply to various eye tissues. Clearly, L-timolol, D-timolol and pilocarpine are good drugs to use in treating glaucoma because they do not reduce blood flow. On the other hand, although moperone reduced IOP effectively, it also decreased blood supply markedly. Therefore, it should not be used for the treatment of glaucoma.

  8. Evaluation of Hepatic Tissue Blood Flow Using Xenon Computed Tomography with Fibrosis Progression in Nonalcoholic Fatty Liver Disease: Comparison with Chronic Hepatitis C

    Directory of Open Access Journals (Sweden)

    Ryuta Shigefuku

    2014-01-01

    Full Text Available Aims: The present study evaluated the utility of xenon computed tomography (Xe-CT as a noninvasive diagnostic procedure for the measurement of hepatic tissue blood flow (TBF in patients with nonalcoholic fatty liver disease (NAFLD or chronic hepatitis C (CH-C. Methods: Xe-CT was performed in 93 patients with NAFLD and in 109 patients with CH-C. Subjects were classified into one of three groups, based on fibrosis stage: group 1, no bridging fibrosis; group 2, bridging fibrosis; and group 3, liver cirrhosis. Correlations between hepatic TBFs in each fibrosis stage were examined. Results: In group 1, portal venous TBF (PVTBF, hepatic arterial (HATBF, and total hepatic TBF (THTBF were significantly lower in patients with in nonalcoholic steatohepatitis (NASH than in those with CH-C (p < 0.001, p < 0.05, p < 0.001, respectively. In group 2, PVTBF and THTBF were significantly lower in patients with in NASH than in those with CH-C (p < 0.001, p < 0.05, respectively. In group 3, hepatic TBFs were not significantly different when comparing patients with NASH and those with CH-C. Conclusions: PVTBF decreased due to fat infiltration. Therefore, hemodynamic changes occur relatively earlier in NAFLD than in CH-C. Patients with NASH should be monitored carefully for portal hypertensive complications in the early fibrosis stage.

  9. Modified Beer-Lambert law for blood flow

    Science.gov (United States)

    Baker, Wesley B.; Parthasarathy, Ashwin B.; Busch, David R.; Mesquita, Rickson C.; Greenberg, Joel H.; Yodh, A. G.

    2015-03-01

    The modified Beer-Lambert law is among the most widely used approaches for analysis of near-infrared spectroscopy (NIRS) reflectance signals for measurements of tissue blood volume and oxygenation. Briefly, the modified Beer-Lambert paradigm is a scheme to derive changes in tissue optical properties based on continuous-wave (CW) diffuse optical intensity measurements. In its simplest form, the scheme relates differential changes in light transmission (in any geometry) to differential changes in tissue absorption. Here we extend this paradigm to the measurement of tissue blood flow by diffuse correlation spectroscopy (DCS). In the new approach, differential changes of the intensity temporal auto-correlation function at a single delay-time are related to differential changes in blood flow. The key theoretical results for measurement of blood flow changes in any tissue geometry are derived, and we demonstrate the new method to monitor cerebral blood flow in a pig under conditions wherein the semi-infinite geometry approximation is fairly good. Specifically, the drug dinitrophenol was injected in the pig to induce a gradual 200% increase in cerebral blood flow, as measured with MRI velocity flow mapping and by DCS. The modified Beer-Lambert law for flow accurately recovered these flow changes using only a single delay-time in the intensity auto-correlation function curve. The scheme offers increased DCS measurement speed of blood flow. Further, the same techniques using the modified Beer-Lambert law to filter out superficial tissue effects in NIRS measurements of deep tissues can be applied to the DCS modified Beer-Lambert law for blood flow monitoring of deep tissues.

  10. Cerebral blood-flow tomography

    DEFF Research Database (Denmark)

    Lassen, N A; Henriksen, L; Holm, S;

    1983-01-01

    Tomographic maps of local cerebral blood flow (CBF) were obtained with xenon-133 and with isopropyl-amphetamine-iodine-123 (IMP) in 11 subjects: one normal, two tumor cases, and eight cerebrovascular cases. A highly sensitive four-face, rapidly rotating, single-photon emission tomograph was used...

  11. Nocturnal variations in peripheral blood flow, systemic blood pressure, and heart rate in humans

    DEFF Research Database (Denmark)

    Sindrup, J H; Kastrup, J; Christensen, H;

    1991-01-01

    Subcutaneous adipose tissue blood flow rate, together with systemic arterial blood pressure and heart rate under ambulatory conditions, was measured in the lower legs of 15 normal human subjects for 12-20 h. The 133Xe-washout technique, portable CdTe(Cl) detectors, and a portable data storage unit...... were used for measurement of blood flow rates. An automatic portable blood pressure recorder and processor unit was used for measurement of systolic blood pressure, diastolic blood pressure, and heart rate every 15 min. The change from upright to supine position at the beginning of the night period...... was associated with a 30-40% increase in blood flow rate and a highly significant decrease in mean arterial blood pressure and heart rate (P less than 0.001 for all). Approximately 100 min after the subjects went to sleep an additional blood flow rate increment (mean 56%) and a simultaneous significant decrease...

  12. Joint probability discrimination between stationary tissue and blood velocity signals

    DEFF Research Database (Denmark)

    Schlaikjer, Malene; Jensen, Jørgen Arendt

    2001-01-01

    In CFM-mode the blood velocity estimates are overlaid onto the B-mode image. The velocity estimation gives non-zero velocity estimates in both the surrounding tissue and the vessels. A discrimination algorithm is needed to determine, which estimates represent blood flow and should be displayed....... This study presents a new statistical discriminator. Investigation of the RF-signals reveals that features can be derived that distinguish the segments of the signal, which do an do not carry information on the blood flow. In this study 4 features, have been determined: (a) the energy content in the segments...

  13. Dexmedetomidine decreases the oral mucosal blood flow.

    Science.gov (United States)

    Kawaai, Hiroyoshi; Yoshida, Kenji; Tanaka, Eri; Togami, Kohei; Tada, Hitoshi; Ganzberg, Steven; Yamazaki, Shinya

    2013-12-01

    There is an abundance of blood vessels in the oral cavity, and intraoperative bleeding can disrupt operations. There have been some interesting reports about constriction of vessels in the oral cavity, one of which reported that gingival blood flow in cats is controlled by sympathetic α-adrenergic fibres that are involved with vasoconstriction. Dexmedetomidine is a sedative and analgesic agent that acts through the α-2 adrenoceptor, and is expected to have a vasoconstrictive action in the oral cavity. We have focused on the relation between the effects of α-adrenoceptors by dexmedetomidine and vasoconstriction in oral tissues, and assessed the oral mucosal blood flow during sedation with dexmedetomidine. The subjects comprised 13 healthy male volunteers, sedated with dexmedetomidine in a loading dose of 6 μg/kg/h for 10 min and a continuous infusion of 0.7 μg/kg/h for 32 min. The mean arterial pressure (MAP), heart rate (HR), cardiac output (CO), stroke volume (SV), systemic vascular resistance (SVR), and palatal mucosal blood flow (PMBF) were measured at 0, 5, 10, 12, 22, and 32 min after the start of the infusion. The HR, CO, and PBMF decreased significantly during the infusion even though there were no differences in the SV. The SVR increased significantly but the PMBF decreased significantly. In conclusion, PMBF was reduced by the mediating effect of dexmedetomidine on α-2 adrenoceptors. PMID:23958351

  14. Ocular Blood Flow Autoregulation Mechanisms and Methods

    Directory of Open Access Journals (Sweden)

    Xue Luo

    2015-01-01

    Full Text Available The main function of ocular blood flow is to supply sufficient oxygen and nutrients to the eye. Local blood vessels resistance regulates overall blood distribution to the eye and can vary rapidly over time depending on ocular need. Under normal conditions, the relation between blood flow and perfusion pressure in the eye is autoregulated. Basically, autoregulation is a capacity to maintain a relatively constant level of blood flow in the presence of changes in ocular perfusion pressure and varied metabolic demand. In addition, ocular blood flow dysregulation has been demonstrated as an independent risk factor to many ocular diseases. For instance, ocular perfusion pressure plays key role in the progression of retinopathy such as glaucoma and diabetic retinopathy. In this review, different direct and indirect techniques to measure ocular blood flow and the effect of myogenic and neurogenic mechanisms on ocular blood flow are discussed. Moreover, ocular blood flow regulation in ocular disease will be described.

  15. Mapping blood flow directionality in the human brain.

    Science.gov (United States)

    Park, Sung-Hong; Do, Won-Joon; Choi, Seung Hong; Zhao, Tiejun; Bae, Kyongtae Ty

    2016-07-01

    Diffusion properties of tissue are often expressed on the basis of directional variance, i.e., diffusion tensor imaging. In comparison, common perfusion-weighted imaging such as arterial spin labeling yields perfusion in a scalar quantity. The purpose of this study was to test the feasibility of mapping cerebral blood flow directionality using alternate ascending/descending directional navigation (ALADDIN), a recently-developed arterial spin labeling technique with sensitivity to blood flow directions. ALADDIN was applied along 3 orthogonal directions to assess directional blood flow in a vector form and also along 6 equally-spaced directions to extract blood flow tensor matrix (P) based on a blood flow ellipsoid model. Tensor elements (eigenvalues, eigenvectors, etc) were calculated to investigate characteristics of the blood flow tensor, in comparison with time-of-flight MR angiogram. While the directions of the main eigenvectors were heterogeneous throughout the brain, regional clusters of blood flow directionality were reproducible across subjects. The technique could show heterogeneous blood flow directionality within and around brain tumor, which was different from that of the contralateral normal side. The proposed method is deemed to provide information of blood flow directionality, which has not been demonstrated before. The results warrant further studies to assess changes in the directionality map as a function of scan parameters, to understand the signal sources, to investigate the possibility of mapping local blood perfusion directionality, and to evaluate its usefulness for clinical diagnosis.

  16. Tissue motion in blood velocity estimation and its simulation

    DEFF Research Database (Denmark)

    Schlaikjer, Malene; Torp-Pedersen, Søren; Jensen, Jørgen Arendt;

    1998-01-01

    Determination of blood velocities for color flow mapping systems involves both stationary echo cancelling and velocity estimation. Often the stationary echo cancelling filter is the limiting factor in color flow mapping and the optimization and further development of this filter is crucial...... to the improvement of color flow imaging. Optimization based on in-vivo data is difficult since the blood and tissue signals cannot be accurately distinguished and the correct extend of the vessel under investigation is often unknown. This study introduces a model for the simulation of blood velocity data in which......, breathing, and anatomy. All three of these motions are handled independently by the simulation program, which also includes a parametric model for the pulsatile velocity in the elastic vessel. The model can be used for optimizing both color flow mapping and spectral display systems...

  17. Correlation of skin temperature and blood flow oscillations

    Science.gov (United States)

    Sagaidachnyi, A. A.; Usanov, D. A.; Skripal, A. V.; Fomin, A. V.

    2012-03-01

    Interrelation of skin temperature and blood flow oscillations of fingers under normal conditions in healthy subjects has been investigated. Oscillations of a blood flow were measured by means of photoplethysmography; oscillations of a temperature were registered by means of thermal imaging camera. The method of blood flow reconstruction by temperature oscillations with the use of the Pennes bioheat transfer equation and a definition of delay time of a temperature in relation to blood flow signal has been described. Temperature oscillations have a lag in relation to blood flow oscillations of approximately 10-20 seconds. Delay time of temperature waves can be used for the definition of an effective thickness of a tissue layer separating blood vessels and skin surface. Use of the described technique of comparison of finger blood flow and temperature oscillations allows to raise correlation coefficient of the signals from 0.35 to 0.63 on average, which testifies of high degree of conditionality of temperature oscillations by blood flow oscillations. The considered method of non-contact restoration of blood flow oscillations by means of temperature oscillation measurements might find practical application in skin thermal lesions research, research of influence of physical and chemical factors on a skin microcirculation.

  18. Our experience of blood flow measurements using radioactive tracers

    International Nuclear Information System (INIS)

    A critical study of blood flow measuring methods is proposed. After a review of the various diffusible and non-diffusible radioactive tracers and the corresponding detector systems, the principles which allow to measure blood flow from the data so obtained, are studied. There is a different principle of flow measurement for each type of tracer. The theory of flow measurement using non-diffusible tracers (human serum albumin labelled with 131I or sup(99m)Tc, 113In-labelled siderophiline) and its application to cardiac flow measurement are described first. Then the theory of flow measurement using diffusible tracers (133Xe, 85Kr) and its application to measurement of blood flow through tissues (muscles and kidney particularly) are described. A personal experience of this various flow measurements is reported. The results obtained, the difficulties encountered and the improvments proposed are developed

  19. Skeletal Blood Flow in Bone Repair and Maintenance

    Institute of Scientific and Technical Information of China (English)

    Ryan E.Tomlinson; Matthew J.Silva

    2013-01-01

    Bone is a highly vascularized tissue, although this aspect of bone is often overlooked. In this article, the importance of blood flow in bone repair and regeneration will be reviewed. First, the skeletal vascular anato-my, with an emphasis on long bones, the distinct mechanisms for vascularizing bone tissue, and methods for remodeling existing vasculature are discussed. Next, techniques for quantifying bone blood flow are briefly summarized. Finally, the body of experimental work that demonstrates the role of bone blood flow in fracture healing, distraction osteogenesis, osteoporosis, disuse osteopenia, and bone grafting is examined. These results illustrate that adequate bone blood flow is an important clinical consideration, particularly during bone regeneration and in at-risk patient groups.

  20. Regulation of cerebral blood flow during exercise.

    Science.gov (United States)

    Querido, Jordan S; Sheel, A William

    2007-01-01

    Constant cerebral blood flow (CBF) is vital to human survival. Originally thought to receive steady blood flow, the brain has shown to experience increases in blood flow during exercise. Although increases have not consistently been documented, the overwhelming evidence supporting an increase may be a result of an increase in brain metabolism. While an increase in metabolism may be the underlying causative factor for the increase in CBF during exercise, there are many modulating variables. Arterial blood gas tensions, most specifically the partial pressure of carbon dioxide, strongly regulate CBF by affecting cerebral vessel diameter through changes in pH, while carbon dioxide reactivity increases from rest to exercise. Muscle mechanoreceptors may contribute to the initial increase in CBF at the onset of exercise, after which exercise-induced hyperventilation tends to decrease flow by pial vessel vasoconstriction. Although elite athletes may benefit from hyperoxia during intense exercise, cerebral tissue is well protected during exercise, and cerebral oxygenation does not appear to pose a limiting factor to exercise performance. The role of arterial blood pressure is important to the increase in CBF during exercise; however, during times of acute hypotension such as during diastole at high-intensity exercise or post-exercise hypotension, cerebral autoregulation may be impaired. The impairment of an increase in cardiac output during exercise with a large muscle mass similarly impairs the increase in CBF velocity, suggesting that cardiac output may play a key role in the CBF response to exercise. Glucose uptake and CBF do not appear to be related; however, there is growing evidence to suggest that lactate is used as a substrate when glucose levels are low. Traditionally thought to have no influence, neural innervation appears to be a protective mechanism to large increases in cardiac output. Changes in middle cerebral arterial velocity are independent of changes in

  1. Synthetic Capillaries to Control Microscopic Blood Flow

    Science.gov (United States)

    Sarveswaran, K.; Kurz, V.; Dong, Z.; Tanaka, T.; Penny, S.; Timp, G.

    2016-02-01

    Capillaries pervade human physiology. The mean intercapillary distance is only about 100 μm in human tissue, which indicates the extent of nutrient diffusion. In engineered tissue the lack of capillaries, along with the associated perfusion, is problematic because it leads to hypoxic stress and necrosis. However, a capillary is not easy to engineer due to its complex cytoarchitecture. Here, it is shown that it is possible to create in vitro, in about 30 min, a tubular microenvironment with an elastic modulus and porosity consistent with human tissue that functionally mimicks a bona fide capillary using “live cell lithography”(LCL) to control the type and position of cells on a composite hydrogel scaffold. Furthermore, it is established that these constructs support the forces associated with blood flow, and produce nutrient gradients similar to those measured in vivo. With LCL, capillaries can be constructed with single cell precision—no other method for tissue engineering offers such precision. Since the time required for assembly scales with the number of cells, this method is likely to be adapted first to create minimal functional units of human tissue that constitute organs, consisting of a heterogeneous population of 100-1000 cells, organized hierarchically to express a predictable function.

  2. Establishing the diffuse correlation spectroscopy signal relationship with blood flow.

    Science.gov (United States)

    Boas, David A; Sakadžić, Sava; Selb, Juliette; Farzam, Parisa; Franceschini, Maria Angela; Carp, Stefan A

    2016-07-01

    Diffuse correlation spectroscopy (DCS) measurements of blood flow rely on the sensitivity of the temporal autocorrelation function of diffusively scattered light to red blood cell (RBC) mean square displacement (MSD). For RBCs flowing with convective velocity [Formula: see text], the autocorrelation is expected to decay exponentially with [Formula: see text], where [Formula: see text] is the delay time. RBCs also experience shear-induced diffusion with a diffusion coefficient [Formula: see text] and an MSD of [Formula: see text]. Surprisingly, experimental data primarily reflect diffusive behavior. To provide quantitative estimates of the relative contributions of convective and diffusive movements, we performed Monte Carlo simulations of light scattering through tissue of varying vessel densities. We assumed laminar vessel flow profiles and accounted for shear-induced diffusion effects. In agreement with experimental data, we found that diffusive motion dominates the correlation decay for typical DCS measurement parameters. Furthermore, our model offers a quantitative relationship between the RBC diffusion coefficient and absolute tissue blood flow. We thus offer, for the first time, theoretical support for the empirically accepted ability of the DCS blood flow index ([Formula: see text]) to quantify tissue perfusion. We find [Formula: see text] to be linearly proportional to blood flow, but with a proportionality modulated by the hemoglobin concentration and the average blood vessel diameter.

  3. Quantifying Blood Flow in the DIEP Flap: An Ultrasonographic Study

    Directory of Open Access Journals (Sweden)

    Joseph Richard Dusseldorp, BCom, MBBS(Hons

    2014-10-01

    Conclusions: This study confirms that perforator size is a critical factor in optimizing blood flow in perforator-based free tissue transfer. Further research is required to understand the flow dynamics of perforator flaps based on multiple perforators. However, surgeons should be cognizant that a single large perforator may have substantially higher flow rates than multiple small perforators. Routine FVI calculation is recommended to ensure complete flap survival.

  4. Connective tissue: Vascular and hematological (blood) support.

    Science.gov (United States)

    Calvino, Nick

    2003-01-01

    Connective Tissue (CT) is a ubiquitous component of all major tissues and structures of the body (50% of all body protein is CT), including that of the blood, vascular, muscle, tendon, ligament, fascia, bone, joint, IVD's (intervertebral discs) and skin. Because of its ubiquitous nature, CT is an often overlooked component of any essential nutritional program that may address the structure, and/or function of these tissues. The central role of CT in the health of a virtually all cells, tissues, organs, and organ systems, is discussed. General nutritional CT support strategies, as well as specific CT support strategies that focus on blood, vascular, structural system (eg, muscles, tendons, ligaments, fascia, bone, and joints), integument (skin) and inflammatory and immune mediation will be discussed here and will deal with connective tissue dynamics and dysfunction. An overview of the current scientific understanding and possible options for naturally enhancing the structure and function of CT through the application of these concepts will be discussed in this article, with specific attention on the vascular and hematological systems.

  5. 21 CFR 870.2120 - Extravascular blood flow probe.

    Science.gov (United States)

    2010-04-01

    ... blood flow probe. (a) Identification. An extravascular blood flow probe is an extravascular ultrasonic or electromagnetic probe used in conjunction with a blood flowmeter to measure blood flow in...

  6. Bone blood flow and metabolism in humans

    DEFF Research Database (Denmark)

    Heinonen, Ilkka; Kemppainen, Jukka; Kaskinoro, Kimmo;

    2012-01-01

    Human bone blood flow and metabolism during physical exercise remains poorly characterised. In the present study we measured femoral bone blood flow and glucose uptake in young healthy subjects by positron emission tomography in three separate protocols. In six women, blood flow was measured...... in femoral bone at rest and during one leg intermittent isometric exercise with increasing exercise intensities. In nine men, blood flow in femur was determined at rest and during dynamic one leg exercise, and two other physiological perturbations: moderate systemic hypoxia (14 O(2) ) at rest and during...... exercise, and during intra-femoral infusion of high-dose adenosine. Bone glucose uptake was measured at rest and during dynamic one leg exercise in five men. The results indicate that isometric exercise increased femoral bone blood flow from rest (1.8 ± 0.6 ml/100g/min) to low intensity exercise (4.1 ± 1...

  7. The Physics of Coronary Blood Flow

    CERN Document Server

    Zamir, M

    2005-01-01

    Coronary blood flow is blood flow to the heart for its own metabolic needs. In the most common form of heart disease there is a disruption in this flow because of obstructive disease in the vessels that carry the flow. The subject of coronary blood flow is therefore associated mostly with the pathophysiology of this disease, rarely with dynamics or physics. Yet, the system responsible for coronary blood flow, namely the "coronary circulation," is a highly sophisticated dynamical system in which the dynamics and physics of the flow are as important as the integrity of the conducting vessels. While an obstruction in the conducting vessels is a fairly obvious and clearly visible cause of disruption in coronary blood flow, any discord in the complex dynamics of the system can cause an equally grave, though less conspicuous, disruption in the flow. This book is devoted specifically to the dynamics and physics of coronary blood flow. While relevance to the clinical and pathophysiological issues is clearly maintaine...

  8. Stochastic modeling for magnetic resonance quantification of myocardial blood flow

    Science.gov (United States)

    Seethamraju, Ravi T.; Muehling, Olaf; Panse, Prasad M.; Wilke, Norbert M.; Jerosch-Herold, Michael

    2000-10-01

    Quantification of myocardial blood flow is useful for determining the functional severity of coronary artery lesions. With advances in MR imaging it has become possible to assess myocardial perfusion and blood flow in a non-invasive manner by rapid serial imaging following injection of contrast agent. To date most approaches reported in the literature relied mostly on deriving relative indices of myocardial perfusion directly from the measured signal intensity curves. The central volume principle on the other hand states that it is possible to derive absolute myocardial blood flow from the tissue impulse response. Because of the sensitivity involved in deconvolution due to noise in measured data, conventional methods are sub-optimal, hence, we propose to use stochastic time series modeling techniques like ARMA to obtain a robust impulse response estimate. It is shown that these methods when applied for the optical estimation of the transfer function give accurate estimates of myocardial blood flow. The most significant advantage of this approach, compared with compartmental tracer kinetic models, is the use of a minimum set of prior assumptions on data. The bottleneck in assessing myocardial blood flow, does not lie in the MRI acquisition, but rather in the effort or time for post processing. It is anticipated that the very limited requirements for user input and interaction will be of significant advantage for the clinical application of these methods. The proposed methods are validated by comparison with mean blood flow measurements obtained from radio-isotope labeled microspheres.

  9. Hepatic and intestinal blood flow following thermal injury

    International Nuclear Information System (INIS)

    Because cardiac output decreases after burn injuries, investigators have assumed, based upon dye clearance techniques, that hepatic and intestinal blood flow are also decreased following these injuries. Blood flow to the liver, stomach, small intestine, and kidney was determined by the uptake of 201thallium and 125I-labeled fatty acid (para-125I-phenyl-3-methyl pentanoic acid) in a 20% body surface area scald injury that also included plasma volume replacement resuscitation. Uptake of these radioisotopes was determined 15 minutes, 18 hours, and 72 hours after injury. The uptake of the 201thallium and 125I-labeled fatty acid by the gastrointestinal tissues was not statistically different at any of the time periods after comparison of the injured and control (sham-treated) animals. 201Thallium uptake by the kidney was significantly diminished 15 minutes after the burn injury (P less than 0.01). Based on these blood flow measurement techniques, the data suggest that the 20% body surface area scald injury did not alter blood flow to the liver or gastrointestinal tract within the initial 72 hours after the burn injury even though a decrease in renal blood flow was easily detected. These results suggest that the dysfunction of the gastrointestinal system or hepatic system observed after an acute burn injury is not simply the result of hypovolemic shock, which reduces both renal and mesenteric blood flow. These gastrointestinal and hepatic alterations may be related to a factor or factors other than intestinal ischemia

  10. Real-time contrast-enhanced ultrasound determination of microvascular blood volume in abdominal subcutaneous adipose tissue in man. Evidence for adipose tissue capillary recruitment

    DEFF Research Database (Denmark)

    Tobin, L; Simonsen, L; Bülow, J

    2010-01-01

    with a 4% coefficient of variation in both tissues. Blood flow and the change in signal intensity as a measure of the microvascular volume increased significantly and simultaneously in abdominal subcutaneous adipose tissue after glucose intake. The forearm blood flow and muscle signal intensity remained...

  11. Retinal blood flow in diabetic retinopathy.

    OpenAIRE

    Patel, V.; Rassam, S; NEWSOM, R.; Wiek, J; Kohner, E.

    1992-01-01

    OBJECTIVES--(a) To report on the basic parameters of retinal blood flow in a population of diabetic patients with and without retinopathy and non-diabetic controls; (b) to formulate a haemodynamic model for the pathogenesis of diabetic retinopathy from this and other studies. DESIGN--Laser-Doppler velocimetry and computerised image analysis to determine retinal blood flow in a large cross sectional study. SETTING--Diabetic retinopathy outpatient clinic. SUBJECTS--24 non-diabetic controls and ...

  12. Hydrodynamic theory of tissue shear flow

    CERN Document Server

    Popović, Marko; Merkel, Matthias; Etournay, Raphaël; Eaton, Suzanne; Jülicher, Frank; Salbreux, Guillaume

    2016-01-01

    We propose a hydrodynamic theory to describe shear flows in developing epithelial tissues. We introduce hydrodynamic fields corresponding to state properties of constituent cells as well as a contribution to overall tissue shear flow due to rearrangements in cell network topology. We then construct a constitutive equation for the shear rate due to topological rearrangements. We identify a novel rheological behaviour resulting from memory effects in the tissue. We show that anisotropic deformation of tissue and cells can arise from two distinct active cellular processes: generation of active stress in the tissue, and actively driven cellular rearrangements. These two active processes result in distinct cellular and tissue shape changes, depending on boundary conditions applied on the tissue. Our findings have consequences for the understanding of tissue morphogenesis during development.

  13. Semiquantitative imaging measurement of baseline and vasomodulated normal prostatic blood flow using sildenafil

    OpenAIRE

    Haaga, JR; Exner, A; Fei, B; Seftel, AD

    2006-01-01

    The physiologic variability of blood flow to the prostate has not been studied until this time. We report the vasoactive effects of sildenafil and phenylephrine on blood flow of the normal prostate. Sildenafil increases prostate blood flow by approximately 75% and phenylephrine reduces the flow incrementally. Administration of these drugs with dynamic contrast-enhanced magnetic resonance imaging may improve the diagnosis of cancerous tissue because according to the literature, tumor angiogeni...

  14. High speed optical holography of retinal blood flow

    Science.gov (United States)

    Pellizzari, M.; Simonutti, M.; Degardin, J.; Sahel, J.-A.; Fink, M.; Paques, M.; Atlan, M.

    2016-08-01

    We performed non-invasive video imaging of retinal blood flow in a pigmented rat by holographic interferometry of near-infrared laser light backscattered by retinal tissue, beating against an off-axis reference beam sampled at a frame rate of 39 kHz with a high throughput camera. Local Doppler contrasts emerged from the envelopes of short-time Fourier transforms and the phase of autocorrelation functions of holograms rendered by Fresnel transformation. This approach permitted imaging of blood flow in large retinal vessels (30 microns diameter) over 400 by 400 pixels with a spatial resolution of 8 microns and a temporal resolution of 6.5 ms.

  15. High speed optical holography of retinal blood flow

    CERN Document Server

    Pellizzari, Mathilde; Degardin, Julie; Sahel, Jose-Alain; Fink, Mathias; Paques, Michel; Atlan, Michael

    2016-01-01

    We performed non-invasive video imaging of retinal blood flow in a pigmented rat by holographic interferometry of near-infrared laser light backscattered by retinal tissue, beating against an off-axis reference beam sampled at a frame rate of 39 kHz with a high throughput camera. Local Doppler contrasts emerged from the envelopes of short-time Fourier transforms and the phase of autocorrelation functions of holograms rendered by Fresnel transformation. This approach permitted imaging of blood flow in large retinal vessels (30 microns diameter) over 400 by 400 pixels with a spatial resolution of 8 microns and a temporal resolution of 6.5 ms.

  16. Methods for blood flow measurements using ultrasound contrast agents

    Science.gov (United States)

    Fowlkes, J. Brian

    2003-10-01

    Blood flow measurements using ultrasound contrast agents are being investigated for myocardial perfusion and more recently in other organ systems. The methods are based largely on the relative increase in echogenicity due to the concentration of bubbles present in the ultrasound beam. In the simplest form, regional differences in blood volume can be inferred but the possibility exists to extract perfusion from the transit of contrast agent through tissue. Perfusion measurements rely on determining the flux of blood through a tissue volume and as such require knowledge of the fractional blood volume (FBV), i.e., ml blood/g tissue and the rate of exchange, commonly measured as the mean transit time (MTT). This presentation will discuss methods of determining each of these values and their combination to estimate tissue perfusion. Underlying principles of indicator-dilution theory will be provided in the context of ultrasound contrast agents. Current methods for determining MTT will include imaging of the intravenous bolus, in-plane contrast disruption with interval and real-time contrast recovery imaging, and control of contrast agent flow using arterial disruption (contrast interruption). The advantages and limitations of the methods will be examined along with current applications. [Work supported in part by NIH.

  17. Determination of the tissue-to-blood partition coefficient for 131iodo-antipyrine in human subcutaneous adipose tissue

    DEFF Research Database (Denmark)

    Jelnes, R; Astrup, A

    1985-01-01

    131Iodo-antipyrine (131I-AP) is commonly used for blood flow measurements in adipose tissue. These estimations have been based on the assumption of the tissue-to-blood partition coefficient being 1 ml g-1. No exact determination of the tissue-to-blood partition coefficient for 131I-AP in adipose...... tissue has been carried out. In the present study a partition coefficient of 1.12 +/- 0.06 (mean +/- S.D.) for 131I-AP in adipose tissue has been determined based on the partition coefficient for 131I-AP between lipid-saline (1.24 ml g-1), red blood cells-plasma (0.64 ml g-1), protein-saline (0.19 ml g-1...

  18. Blood flow in skin, subcutaneous adipose tissue and skeletal muscle in the forearm of normal man during an oral glucose load

    DEFF Research Database (Denmark)

    Bülow, J; Astrup, A; Christensen, N J;

    1987-01-01

    decreased to 4.5 +/- 0.34 mmol l-1 at the end of the experiment. In the control experiments glucose concentration was constant. Arterial noradrenaline concentration increased significantly from 1.0 +/- 0.13 to about 1.5 +/- 0.3 nmol l-1 120 min after glucose and remained at this level during the experiment....... Similarly adrenaline increased from 0.16 +/- 0.11 to about 0.4 +/- 0.16 nmol l-1 180 min after glucose. It is hypothesized that the vasodilating effect of glucose in subcutaneous tissue is secondary to metabolic events connected to glucose uptake and energy deposition in adipose tissue....

  19. [The landmarks of the measurement of cerebral blood flow].

    Science.gov (United States)

    István, Nyáry

    2008-01-30

    History of the measurement of local cerebral blood flow may cover a period of one and a half centuries. Parallel forthcoming of both theoretical and technical development were the key elements of ensuing progress resulting in the present state, when by the aid of in vivo blood flow and metabolic maps, we can visualize locales of brain functioning and their interconnections. Two theoretical landmarks should be mentioned in this historic process. First, the work of Adolf Fick, as the starter of quantitative measurements in this field, and Seymour Kety's model of a single, homogenously perfused tissue element. The solution of this model, in the form of Kety's equation is still fundamental to present day blood flow mapping techniques. Among the numerous investigators over the past years, two Hungarian scientist can be named as major contributors. Kálmán Sántha made substantial studies with continuous registration of local cerebral blood flow by the aid of thermocouples, while Emil P6sztor invented the hydrogen clearance method for the measurement of local cerebral blood flow both in human and in animal studies.

  20. An implantable blood pressure and flow transmitter.

    Science.gov (United States)

    Rader, R. D.; Meehan, J. P.; Henriksen, J. K. C.

    1973-01-01

    A miniature totally implantable FM/FM telemetry system has been developed to simultaneously measure blood pressure and blood flow, thus providing an appreciation of the hemodynamics of the circulation to the entire body or to a particular organ. Developed for work with animal subjects, the telemetry system's transmission time is controlled by an RF signal that permits an operating life of several months. Pressure is detected by a miniature intravascular transducer and flow is detected by an extravascular interferometric ultrasonic technique. Both pressure and flow are calibrated prior to implanting. The pressure calibration can be checked after the implanting by cannulation; flow calibration can be verified only at the end of the experiment by determining the voltage output from the implanted sensing system as a function of several measured flow rates. The utility of this device has been established by its use in investigating canine renal circulation during exercise, emotional encounters, administration of drugs, and application of accelerative forces.

  1. The regulation of subcutaneous adipose tissue blood flow in the ischaemic forefoot during 24 hours. Studies using the 133-xenon wash-out technique continuously over 24 hours

    DEFF Research Database (Denmark)

    Jelnes, R

    1988-01-01

    in 0.1 ml isotonic saline injected into the subcutaneous adipose tissue in the forefoot. The detector is connected to a memory unit allowing for storage of data. Due to the short distance, the recorded elimination rate constant must be corrected for combined convection and diffusion of the radioactive...... within normal range. SBF during day-time activities decreased by up to 50% postoperatively. This is caused by the reappearance of the local, sympathetic, veno-arteriolar vasoconstrictor response. During sleep SBF increased by 71%. The term postreconstructive hyperaemia seems improper, at least in a long-term...

  2. Blood flow characteristics in the aortic arch

    Science.gov (United States)

    Prahl Wittberg, Lisa; van Wyk, Stevin; Mihaiescu, Mihai; Fuchs, Laszlo; Gutmark, Ephraim; Backeljauw, Philippe; Gutmark-Little, Iris

    2012-11-01

    The purpose with this study is to investigate the flow characteristics of blood in the aortic arch. Cardiovascular diseases are associated with specific locations in the arterial tree. Considering atherogenesis, it is claimed that the Wall Shear Stress (WSS) along with its temporal and spatial gradients play an important role in the development of the disease. The WSS is determined by the local flow characteristics, that in turn depends on the geometry as well as the rheological properties of blood. In this numerical work, the time dependent fluid flow during the entire cardiac cycle is fully resolved. The Quemada model is applied to account for the non-Newtonian properties of blood, an empirical model valid for different Red Blood Cell loading. Data obtained through Cardiac Magnetic Resonance Imaging have been used in order to reconstruct geometries of the the aortic arch. Here, three different geometries are studied out of which two display malformations that can be found in patients having the genetic disorder Turner's syndrome. The simulations show a highly complex flow with regions of secondary flow that is enhanced for the diseased aortas. The financial support from the Swedish Research Council (VR) and the Sweden-America Foundation is gratefully acknowledged.

  3. Analysis of blood and tissue in gallbladder cancer

    Energy Technology Data Exchange (ETDEWEB)

    Rautray, T.R. [Department of Dental Biomaterials, School of Dentistry, Kyungpook National University, 2-188-1 Samduk-dong, Jung-gu, Daegu (Korea, Republic of)], E-mail: tapash77@hotmail.com; Vijayan, V. [Dept. of Physics, Valliammai Engineering College, SRM Nagar, Chennai (India); Sudarshan, M. [UGC-DAE Consortium for Scientific Research, Kolkata Centre, 3/LB-8 Bidhan Nagar, Kolkata 700 098, West Bengal (India); Panigrahi, S. [Dept. of Physics, National Institute of Technology, Rourkela 769 008, Orissa (India)

    2009-09-01

    Particle induced X-ray emission, particle induced {gamma}-ray emission studies has been carried out to analyse normal and carcinoma tissues and blood samples of gallbladder of both sexes and seventeen trace elements namely Na, Mg, Al, K, Ca, Ti, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Br and Pb were estimated in the tissue and blood samples. In the present study, concentration of Zn in the carcinoma gallbladder tissue is less than that of the normal gallbladder tissue. Tobacco habit could be one of the important factors to decrease the elemental concentrations in blood and tissue samples.

  4. Uteroplacental blood flow during alkalosis in the sheep

    International Nuclear Information System (INIS)

    Uteroplacental blood flow was measured by the radioactive-microsphere technique in eight near-term pregnant ewes during a normal control period and during maternal metabolic alkalosis. All measurements were made on awake, unanesthetized animals. Alkalosis, defined for this study as an arterial pH of 7.60 or greater, was produced by the oral administration of sodium bicarbonate, 3 g/kg body wt. The rise in pH thus produced was unaccompanied by significant changes in systemic arterial blood pressure and cardiac output, while maternal arterial P/sub CO2/ rose slightly from control levels. Cotyledonary blood flow declined from a control value of 1.177 ml/min to 1.025 ml/min during alkalosis. This decline of 13 percent in cotyledonary blood flow is significant (P less than 0.02). Blood flow to the remaining uterine tissue, or noncotyledonary uterus, did not change with alkalosis, being maintained at approximately 195 ml/min. It is concluded that maternal alkalosis, unaccompanied by major changes in P /sub CO2/ and systemic arterial pressure, causes a small increase in the resistance of the uteroplacental circulation

  5. Electromechanical Model of Blood Flow in Vessels

    OpenAIRE

    Ivo Cap; Barbora Czippelova

    2008-01-01

    The present paper deals with some theoretical derivations connected with very efficient method of solution of hydrodynamic problems of blood flow in human cardiovascular system. The electromechanical analogy of liquid flow in a tube and electromagnetic wave propagating along an electric transmission line is discussed. We have derived a detailed circuit-like model of an elementary section of the elastic tube with viscose Newtonian liquid. The analogy harmonic current electrical cir...

  6. Vasodilator interactions in skeletal muscle blood flow regulation

    DEFF Research Database (Denmark)

    Hellsten, Ylva; Nyberg, Michael Permin; Jensen, Lasse Gliemann;

    2012-01-01

    During exercise, oxygen delivery to skeletal muscle is elevated to meet the increased oxygen demand. The increase in blood flow to skeletal muscle is achieved by vasodilators formed locally in the muscle tissue, either on the intraluminal or the extraluminal side of the blood vessels. A number...... vasodilators are both stimulated by several compounds, eg. adenosine, ATP, acetylcholine, bradykinin, and are affected by mechanically induced signals, such as shear stress. NO and prostacyclin have also been shown to interact in a redundant manner where one system can take over when formation of the other...... that this remaining hyperemia may be explained by cAMP and cGMP independent smooth muscle relaxation, such as effects of endothelial derived hyperpolarization factors (EDHFs) or through metabolic modulation of sympathetic effects. The nature and role of EDHF as well as potential novel mechanisms in muscle blood flow...

  7. Measurement of tumor blood flow following neutron irradiation

    International Nuclear Information System (INIS)

    Clinical oncologists and cancer researchers benefit from information on the vascularization or non-vascularization of solid tumors because of blood flow's influence on three popular treatment types: hyperthermia therapy, radiotherapy, and chemotherapy. The objective of this research is the development of a clinically useful tumor blood flow measurements technique. The designed technique is sensitive, has good spatial resolution, in non-invasive and presents no risk to the patient beyond his usual treatment. Tumor blood flow was determined by measuring the washout of positron emitting isotopes created through neutron therapy treatment. In order to do this, several technical and scientific questions were addressed first. These questions have been answered through both theoretical calculation and measurement. The first question was answered through the measurement of macroscopic cross sections for the predominant nuclear reactions in the body. These results correlate well with an independent mathematical prediction of tissue activation and measurements of mouse spleen neutron activation. The second question was addressed by performing cell suspension and protein precipitation techniques on neutron activated mouse spleens. The third and final question was answered by using first physical principles to develop a model mimicking the blood flow system and measurement technique. In a final set of experiments, the above were applied to flow models and animals. The ultimate aim of this project is to apply its methodology to neutron therapy patients

  8. Blood flow dynamics in the snake spectacle.

    Science.gov (United States)

    van Doorn, Kevin; Sivak, Jacob G

    2013-11-15

    The eyes of snakes are shielded beneath a layer of transparent integument referred to as the 'reptilian spectacle'. Well adapted to vision by virtue of its optical transparency, it nevertheless retains one characteristic of the integument that would otherwise prove detrimental to vision: its vascularity. Given the potential consequence of spectacle blood vessels on visual clarity, one might expect adaptations to have evolved that mitigate their negative impact. Earlier research demonstrated an adaptation to their spatial layout in only one species to reduce the vessels' density in the region serving the foveal and binocular visual fields. Here, we present a study of spectacle blood flow dynamics and provide evidence of a mechanism to mitigate the spectacle blood vessels' deleterious effect on vision by regulation of blood flow through them. It was found that when snakes are at rest and undisturbed, spectacle vessels undergo cycles of dilation and constriction, such that the majority of the time the vessels are fully constricted, effectively removing them from the visual field. When snakes are presented with a visual threat, spectacle vessels constrict and remain constricted for longer periods than occur during the resting cycles, thus guaranteeing the best possible visual capabilities in times of need. Finally, during the snakes' renewal phase when they are generating a new stratum corneum, the resting cycle is abolished, spectacle vessels remain dilated and blood flow remains strong and continuous. The significance of these findings in terms of the visual capabilities and physiology of snakes is discussed.

  9. Cerebral blood flow in acute mountain sickness

    DEFF Research Database (Denmark)

    Jensen, J B; Wright, Anne; Lassen, N A;

    1990-01-01

    Changes in cerebral blood flow (CBF) were measured using the radioactive xenon technique and were related to the development of acute mountain sickness (AMS). In 12 subjects, ascending from 150 to 3,475 m, CBF was 24% increased at 24 h [45.1 to 55.9 initial slope index (ISI) units] and 4% increased...

  10. Effects of aortic irregularities on blood flow.

    Science.gov (United States)

    Prahl Wittberg, Lisa; van Wyk, Stevin; Fuchs, Laszlo; Gutmark, Ephraim; Backeljauw, Philippe; Gutmark-Little, Iris

    2016-04-01

    Anatomic aortic anomalies are seen in many medical conditions and are known to cause disturbances in blood flow. Turner syndrome (TS) is a genetic disorder occurring only in females where cardiovascular anomalies, particularly of the aorta, are frequently encountered. In this study, numerical simulations are applied to investigate the flow characteristics in four TS patient- related aortic arches (a normal geometry, dilatation, coarctation and elongation of the transverse aorta). The Quemada viscosity model was applied to account for the non-Newtonian behavior of blood. The blood is treated as a mixture consisting of water and red blood cells (RBC) where the RBCs are modeled as a convected scalar. The results show clear geometry effects where the flow structures and RBC distribution are significantly different between the aortas. Transitional flow is observed as a jet is formed due to a constriction in the descending aorta for the coarctation case. RBC dilution is found to vary between the aortas, influencing the WSS. Moreover, the local variations in RBC volume fraction may induce large viscosity variations, stressing the importance of accounting for the non-Newtonian effects. PMID:26104133

  11. Frequency encoding in renal blood flow regulation

    DEFF Research Database (Denmark)

    Marsh, Donald J; Sosnovtseva, Olga; Pavlov, Alexey N;

    2005-01-01

    With a model of renal blood flow regulation, we examined consequences of tubuloglomerular feedback (TGF) coupling to the myogenic mechanism via voltage-gated Ca channels. The model reproduces the characteristic oscillations of the two mechanisms and predicts frequency and amplitude modulation...

  12. Cerebral blood flow tomography with xenon-133

    DEFF Research Database (Denmark)

    Lassen, N A

    1985-01-01

    Cerebral blood flow (CBF) can be measured tomographically by inhalation of Xenon-133. The calculation is based on taking a sequence of tomograms during the wash-in and wash-out phase of the tracer. Due to the dynamic nature of the process, a highly sensitive and fast moving single photon emission...

  13. Frequency encoding in renal blood flow regulation

    DEFF Research Database (Denmark)

    Marsh, D.J.; Sosnovtseva, Olga; Pavlov, A.N.;

    2005-01-01

    With a model of renal blood flow regulation, we examined consequences of tubuloglomerular feedback (TGF) coupling to the myogenic mechanism via voltage-gated Ca channels. The model reproduces the characteristic oscillations of the two mechanisms and predicts frequency and amplitude modulation of ...

  14. Xenon computed tomographic blood flow mapping

    International Nuclear Information System (INIS)

    Xenon CT flow information appears to be clinically useful in the diagnosis and management of a broad spectrum of clinical disorders. It also appears to be a useful tool for the experimental study of the cerebral circulation, with recent work also extending to application to the study of solid abdominal organs. The authors therefore found xenon CT CBF mapping to be a useful new blood flow methodology and are of the opinion that as CT technology improves, one will be able to obtain still better flow information with less accompanying radiation exposure and/or a reduction in the level of xenon inhalation required

  15. Quantitative blood flow velocity imaging using laser speckle flowmetry

    Science.gov (United States)

    Nadort, Annemarie; Kalkman, Koen; van Leeuwen, Ton G.; Faber, Dirk J.

    2016-04-01

    Laser speckle flowmetry suffers from a debated quantification of the inverse relation between decorrelation time (τc) and blood flow velocity (V), i.e. 1/τc = αV. Using a modified microcirculation imager (integrated sidestream dark field - laser speckle contrast imaging [SDF-LSCI]), we experimentally investigate on the influence of the optical properties of scatterers on α in vitro and in vivo. We found a good agreement to theoretical predictions within certain limits for scatterer size and multiple scattering. We present a practical model-based scaling factor to correct for multiple scattering in microcirculatory vessels. Our results show that SDF-LSCI offers a quantitative measure of flow velocity in addition to vessel morphology, enabling the quantification of the clinically relevant blood flow, velocity and tissue perfusion.

  16. Real-time contrast-enhanced ultrasound determination of microvascular blood volume in abdominal subcutaneous adipose tissue in man. Evidence for adipose tissue capillary recruitment

    DEFF Research Database (Denmark)

    Tobin, L; Simonsen, L; Bülow, J

    2010-01-01

    The adipose tissue metabolism is dependent on its blood perfusion. During lipid mobilization e.g. during exercise and during lipid deposition e.g. postprandial, adipose tissue blood flow is increased. This increase in blood flow may involve capillary recruitment in the tissue. We investigated...... the basic and postprandial microvascular volume in adipose tissue using real-time contrast-enhanced ultrasound (CEU) imaging in healthy normal weight subjects. In nine subjects, CEU was performed in abdominal subcutaneous adipose tissue and in the underlying skeletal muscle after a bolus injection...... of ultrasound contrast agent to establish the reproducibility of the technique. In nine subjects, the effect of an oral glucose load on blood flow and microvascular volume was measured in abdominal subcutaneous adipose tissue and forearm skeletal muscle. ¹³³Xe washout and venous occlusion strain...

  17. Modeling of blood flow in arterial trees.

    Science.gov (United States)

    Anor, Tomer; Grinberg, Leopold; Baek, Hyoungsu; Madsen, Joseph R; Jayaraman, Mahesh V; Karniadakis, George E

    2010-01-01

    Advances in computational methods and medical imaging techniques have enabled accurate simulations of subject-specific blood flows at the level of individual blood cell and in complex arterial networks. While in the past, we were limited to simulations with one arterial bifurcation, the current state-of-the-art is simulations of arterial networks consisting of hundreds of arteries. In this paper, we review the advances in methods for vascular flow simulations in large arterial trees. We discuss alternative approaches and validity of various assumptions often made to simplify the modeling. To highlight the similarities and discrepancies of data computed with different models, computationally intensive three-dimensional (3D) and inexpensive one-dimensional (1D) flow simulations in very large arterial networks are employed. Finally, we discuss the possibilities, challenges, and limitations of the computational methods for predicting outcomes of therapeutic interventions for individual patients. PMID:20836052

  18. Arterial secondary blood flow patterns visualized with vector flow ultrasound

    DEFF Research Database (Denmark)

    Pedersen, Mads Møller; Pihl, Michael Johannes; Hansen, Jens Munk;

    2011-01-01

    This study presents the first quantification and visualisation of secondary flow patterns with vector flow ultrasound. The first commercial implementation of the vector flow method Transverse Oscillation was used to obtain in-vivo, 2D vector fields in real-time. The hypothesis of this study...... was that the rotational direction is constant within each artery. Three data sets of 10 seconds were obtained from three main arteries in healthy volunteers. For each data set the rotational flow patterns were identified during the diastole. Each data set contains a 2D vector field over time and with the vector angles...... and velocity magnitudes the blood flow patterns were visualised with streamlines in Matlab (Mathworks, Natick, MA, USA). The rotational flow was quantified by the angular frequency for each cardiac cycle, and the mean rotational frequencies and standard deviations were calculated for the abdominal aorta f-1...

  19. Microwave imaging of tissue blood content changes.

    Science.gov (United States)

    Hawley, M S; Broquetas, A; Jofre, L; Bolomey, J C; Gaboriaud, G

    1991-05-01

    Active microwave imaging gives information on the dielectric properties of of the body, allowing the collection of data that are distinct from, but complementary to, those available from other imaging methods based on different radiations. Two types of microwave imaging systems have been developed. The first is a planar system that irradiates the object with a plane wave and collects scattered phase and amplitude data at 1024 points on a parallel plane. The data can be reconstructed using a back propagation technique to give an image of the object. The second type of system is a tomographic scanner, consisting of a multiplexed 64-element circular array of waveguides. The waveguides are electronically scanned, alternately as sources and receivers, to give a complete scan of the object with no mechanical movement. A tomographic 'slice' of the object is reconstructed using spectral domain interpolation. Both systems work at 2.45 GHz with an incident power less than 1 mW cm-2 at the object and require a coupling medium (usually water) between the object and the source/receiver. Imaging parameters are appropriate for clinical use: a spatial resolution of 1 cm, measurement time of a few seconds and contrast resolution of around 1%. The effects of changes in perfusion on images of isolated animal organs are presented. Images have also been obtained, with both systems, of the internal dielectric structure of the forearm and of variations in dielectric properties due to changes of tissue blood content effected by application and release of tourniquets to the upper arm. Results show that these changes are well demonstrated by microwave imaging, and possible clinical applications are discussed. PMID:1870328

  20. Ocular Blood Flow and Normal Tension Glaucoma

    Directory of Open Access Journals (Sweden)

    Ning Fan

    2015-01-01

    Full Text Available Normal tension glaucoma (NTG is known as a multifactorial optic neuropathy characterized by progressive retinal ganglion cell death and glaucomatous visual field loss, even though the intraocular pressure (IOP does not exceed the normal range. The pathophysiology of NTG remains largely undetermined. It is hypothesized that the abnormal ocular blood flow is involved in the pathogenesis of this disease. A number of evidences suggested that the vascular factors played a significant role in the development of NTG. In recent years, the new imaging techniques, fluorescein angiography, color Doppler imaging (CDI, magnetic resonance imaging (MRI, and laser speckle flowgraphy (LSFG, have been used to evaluate the ocular blood flow and blood vessels, and the impaired vascular autoregulation was found in patients with NTG. Previous studies showed that NTG was associated with a variety of systemic diseases, including migraine, Alzheimer’s disease, primary vascular dysregulation, and Flammer syndrome. The vascular factors were involved in these diseases. The mechanisms underlying the abnormal ocular blood flow in NTG are still not clear, but the risk factors for glaucomatous optic neuropathy likely included oxidative stress, vasospasm, and endothelial dysfunction.

  1. Glial and neuronal control of brain blood flow

    DEFF Research Database (Denmark)

    Attwell, David; Buchan, Alastair M; Charpak, Serge;

    2010-01-01

    Blood flow in the brain is regulated by neurons and astrocytes. Knowledge of how these cells control blood flow is crucial for understanding how neural computation is powered, for interpreting functional imaging scans of brains, and for developing treatments for neurological disorders. It is now...... recognized that neurotransmitter-mediated signalling has a key role in regulating cerebral blood flow, that much of this control is mediated by astrocytes, that oxygen modulates blood flow regulation, and that blood flow may be controlled by capillaries as well as by arterioles. These conceptual shifts...... in our understanding of cerebral blood flow control have important implications for the development of new therapeutic approaches....

  2. Tissue distribution of histo-blood group antigens

    DEFF Research Database (Denmark)

    Ravn, V; Dabelsteen, Erik

    2000-01-01

    The introduction of immunohistochemical techniques and monoclonal antibodies to specific carbohydrate epitopes has made it possible to study in detail the tissue distribution of histo-blood group antigens and related carbohydrate structures. The present paper summarizes the available data...... concerning the histological distribution of histo-blood group antigens and their precursor structures in normal human tissues. Studies performed have concentrated on carbohydrate antigens related to the ABO, Lewis, and TTn blood group systems, i.e. histo-blood group antigens carried by type 1, 2, and 3 chain...... carrier carbohydrate chains. Histo-blood group antigens are found in most epithelial tissues. Meanwhile, several factors influence the type, the amount, and the histological distribution of histoblood group antigens, i.e. the ABO, Lewis, and saliva-secretor type of the individual, and the cell- and tissue...

  3. Regional blood flow studies with radioisotopes

    International Nuclear Information System (INIS)

    The methodological approaches to blood flow analysis include (1) diffusible indicator methods, (2) clearance techniques and (3) nondiffusible indicator methods. In each case, accurate measurements of blood flow can be obtained by developing mathematical models which relate the time-dependent observation derived from following the fate of a radiotracer as a function of time to the physiological process itself. Application of these models to biological systems involves constraints and necessitates compromises which may affect the validity of the measurements. Nevertheless, when these techniques are carefully applied and adequately validated, they have provided critical physiological information about such organ systems as the brain and kidney and promise to provide diagnostic information in patients with suspected coronary and peripheral vascular disease

  4. Caffeine reduces myocardial blood flow during exercise.

    Science.gov (United States)

    Higgins, John P; Babu, Kavita M

    2013-08-01

    Caffeine consumption has been receiving increased interest from both the medical and lay press, especially given the increased amounts now available in energy products. Acute ingestion of caffeine usually increases cardiac work; however, caffeine impairs the expected proportional increase in myocardial blood flow to match this increased work of the heart, most notably during exercise. This appears to be mainly due to caffeine's effect on blocking adenosine-induced vasodilatation in the coronary arteries in normal healthy subjects. This review summarizes the available medical literature specifically relating to pure caffeine tablet ingestion and reduced exercise coronary blood flow, and suggests possible mechanisms. Further studies are needed to evaluate this effect for other common caffeine-delivery systems, including coffee, energy beverages, and energy gels, which are often used for exercise performance enhancement, especially in teenagers and young athletes. PMID:23764265

  5. Blood flow-restricted exercise in space

    OpenAIRE

    Hackney, Kyle J; Everett, Meghan; Scott, Jessica M; Ploutz-Snyder, Lori

    2012-01-01

    Prolonged exposure to microgravity results in chronic physiological adaptations including skeletal muscle atrophy, cardiovascular deconditioning, and bone demineralization. To attenuate the negative consequences of weightlessness during spaceflight missions, crewmembers perform moderate- to high-load resistance exercise in conjunction with aerobic (cycle and treadmill) exercise. Recent evidence from ground-based studies suggests that low-load blood flow-restricted (BFR) resistance exercise tr...

  6. Red blood cell in simple shear flow

    Science.gov (United States)

    Chien, Wei; Hew, Yayu; Chen, Yeng-Long

    2013-03-01

    The dynamics of red blood cells (RBC) in blood flow is critical for oxygen transport, and it also influences inflammation (white blood cells), thrombosis (platelets), and circulatory tumor migration. The physical properties of a RBC can be captured by modeling RBC as lipid membrane linked to a cytoskeletal spectrin network that encapsulates cytoplasm rich in hemoglobin, with bi-concave equilibrium shape. Depending on the shear force, RBC elasticity, membrane viscosity, and cytoplasm viscosity, RBC can undergo tumbling, tank-treading, or oscillatory motion. We investigate the dynamic state diagram of RBC in shear and pressure-driven flow using a combined immersed boundary-lattice Boltzmann method with a multi-scale RBC model that accurately captures the experimentally established RBC force-deformation relation. It is found that the tumbling (TU) to tank-treading (TT) transition occurs as shear rate increases for cytoplasm/outer fluid viscosity ratio smaller than 0.67. The TU frequency is found to be half of the TT frequency, in agreement with experiment observations. Larger viscosity ratios lead to the disappearance of stable TT phase and unstable complex dynamics, including the oscillation of the symmetry axis of the bi-concave shape perpendicular to the flow direction. The dependence on RBC bending rigidity, shear modulus, the order of membrane spectrin network and fluid field in the unstable region will also be discussed.

  7. Aortic blood flow subtraction: an alternative method for measuring total renal blood flow in conscious dogs

    DEFF Research Database (Denmark)

    Sandgaard, N C F; Andersen, J L; Holstein-Rathlou, N-H;

    2002-01-01

    We have measured total renal blood flow (TRBF) as the difference between signals from ultrasound flow probes implanted around the aorta above and below the renal arteries. The repeatability of the method was investigated by repeated, continuous infusions of angiotensin II and endothelin-1 seven...

  8. High speed optical holography of retinal blood flow.

    Science.gov (United States)

    Pellizzari, M; Simonutti, M; Degardin, J; Sahel, J-A; Fink, M; Paques, M; Atlan, M

    2016-08-01

    We performed noninvasive video imaging of retinal blood flow in a pigmented rat by holographic interferometry of near-infrared laser light backscattered by retinal tissue, beating against an off-axis reference beam sampled at a frame rate of 39 kHz with a high throughput camera. Local Doppler contrasts emerged from the envelopes of short-time Fourier transforms and the phase of autocorrelation functions of holograms rendered by Fresnel transformation. This approach permitted imaging of blood flow in large retinal vessels (∼30 microns diameter) over 400×400  pixels with a spatial resolution of ∼8 microns and a temporal resolution of ∼6.5  ms.

  9. High speed optical holography of retinal blood flow.

    Science.gov (United States)

    Pellizzari, M; Simonutti, M; Degardin, J; Sahel, J-A; Fink, M; Paques, M; Atlan, M

    2016-08-01

    We performed noninvasive video imaging of retinal blood flow in a pigmented rat by holographic interferometry of near-infrared laser light backscattered by retinal tissue, beating against an off-axis reference beam sampled at a frame rate of 39 kHz with a high throughput camera. Local Doppler contrasts emerged from the envelopes of short-time Fourier transforms and the phase of autocorrelation functions of holograms rendered by Fresnel transformation. This approach permitted imaging of blood flow in large retinal vessels (∼30 microns diameter) over 400×400  pixels with a spatial resolution of ∼8 microns and a temporal resolution of ∼6.5  ms. PMID:27472604

  10. Quantification of myocardial blood flow and blood flow reserve in the presence of arterial dispersion: a simulation study.

    Science.gov (United States)

    Schmitt, Melanie; Viallon, Magalie; Thelen, Manfred; Schreiber, Wolfgang G

    2002-04-01

    Myocardial blood flow (MBF) can be quantified using dynamic T1-weighted MRI of diffusible tracers and a mathematical model of underlying vasculature. Quantification of MBF by means of T1- weighted MRI requires knowledge of the arterial input function (AIF). The AIF can be estimated from the left ventricular (LV) cavity. However, dispersion may occur between the LV and the tissue of interest because of the laminar blood flow profiles, branching of venules, and because of stenosis. To evaluate the influence of dispersion on the results of MBF quantification, a simulation study was performed. The dispersion was described as a convolution of the AIF with an exponential residue function. Synthetic tissue and AIF curves were analyzed and the derived parameters fit to the simulated parameters. The results show that an unaccounted dispersion may result in a systematic underestimation of MBF up to approximately 50%. Underestimation increases with increasing dispersion and with increasing MBF. Assuming equal dispersion at rest and during hyperemia, myocardial perfusion reserve (MPR) estimates are also susceptible to underestimation of approximately 20%. An unaccounted dispersion therefore can lead to systematic underestimation of both blood flow and perfusion reserve.

  11. Surfactant bolus instillation: effects of different doses on blood pressure and cerebral blood flow velocities

    OpenAIRE

    Rey, M.; Segerer, Hugo; Kiessling, C.; Obladen, Michael

    1994-01-01

    Fifteen preterm infants suffering from respiratory distress syndrome were randomly allocated to receive either high-dose (200 mg/kg) or low-dose (100 mg/kg) surfactant treatment. Retreatments were done with the low dose. Blood pressure, blood gases and cerebral blood flow velocities were determined before and after 24 bolus instillations. With the high dose mean blood pressure and mean cerebral blood flow velocity dropped significantly. With the low dose only mean cerebral blood flow velocity...

  12. Biology and Mechanics of Blood Flows Part I: Biology

    CERN Document Server

    Thiriet, Marc

    2008-01-01

    Biology and Mechanics of Blood Flows presents the basic knowledge and state-of-the-art techniques necessary to carry out investigations of the cardiovascular system using modeling and simulation. Part I of this two-volume sequence, Biology, addresses the nanoscopic and microscopic scales. The nanoscale corresponds to the scale of biochemical reaction cascades involved in cell adaptation to mechanical stresses among other stimuli. The microscale is the scale of stress-induced tissue remodeling associated with acute or chronic loadings. The cardiovascular system, like any physiological system, has a complicated three-dimensional structure and composition. Its time dependent behavior is regulated, and this complex system has many components. In this authoritative work, the author provides a survey of relevant cell components and processes, with detailed coverage of the electrical and mechanical behaviors of vascular cells, tissues, and organs. Because the behaviors of vascular cells and tissues are tightly coupl...

  13. Regional cerebral blood flow in childhood headache

    International Nuclear Information System (INIS)

    Regional cerebral blood flow (rCBF) was measured in 16 cranial regions in 23 children and adolescents with frequent headaches using the non-invasive Xenon-133 inhalation technique. Blood flow response to 5% carbon dioxide (CO2) was also determined in 21 patients, while response to 50% oxygen was measured in the two patients with hemoglobinopathy. Included were 10 patients with a clinical diagnosis of migraine, 4 with musculoskeletal headaches, and 3 with features of both types. Also studied were 2 patients with primary thrombocythemia, 2 patients with hemoglobinopathy and headaches, 1 patient with polycythemia, and 1 with headaches following trauma. With two exceptions, rCBF determinations were done during an asymptomatic period. Baseline rCBF values tended to be higher in these young patients than in young adults done in our laboratory. Localized reduction in the expected blood flow surge after CO2 inhalation, most often noted posteriorly, was seen in 8 of the 13 vascular headaches, but in none of the musculoskeletal headache group. Both patients with primary thrombocythemia had normal baseline flow values and altered responsiveness to CO2 similar to that seen in migraineurs; thus, the frequently reported headache and transient neurologic signs with primary thrombocythemia are probably not due to microvascular obstruction as previously suggested. These data support the concept of pediatric migraine as a disorder of vasomotor function and also add to our knowledge of normal rCBF values in younger patients. Demonstration of altered vasomotor reactivity to CO2 could prove helpful in children whose headache is atypical

  14. Structured Tree Outflow Condition for Blood Flow in Arteries

    Science.gov (United States)

    Olufsen, Mette

    1998-11-01

    Modeling blood flow and especially propagation of the pulse wave in the systemic arteries is of interests to the medical society because of the significance of the dicrotic wave. The pulse wave propagating along the larger arteries is reflected because of tapering and branching of the vessels, as well as the peripheral resistance, which is mainly stemming from the smaller arteries and arterioles. In order to avoid artificial reflections it is important to determine a boundary condition, representing the smaller arteries and arterioles, which is physiologically correct. In this work we have proposed a boundary condition based on a structured tree model. The result will be compared both with other modeling approaches as well as with results from measurements of flow and pressure at a number of locations along the larger arteries. The model for the larger arteries is based on the axisymmetrical Navier Stokes equations where the blood is assumed Newtonian and incompressible and the vessels are tapering. In the structured tree the model is based on a linearization of the axisymmetrical Navier-Stokes equations. The reason for setting up a structured tree is that the smaller arteries consist of an almost binary tree. Furthermore, the role of the smaller arteries is to allow blood perfusion of specific tissues. This is done in a structured and optimal way such that the smaller arteries cover the tissue evenly using a minimization principle.

  15. Regional cerebral blood flow in diabetic patients

    International Nuclear Information System (INIS)

    N-isopropyl-p-123I-iodoamphetamine (IMP) was used to quantify the regional cerebral blood flow (r-CBF) in 11 diabetic patients (average age; 67.9 years) and 12 non-diabetic subjects (average age; 67.4 years), none of whom had (cerebrovascular disease (CVD) on CT studies. A reference sampling method by continuous arterial blood sampling was used to quantify r-CBF. There were no significant differences in physiological or laboratory data between diabetic and non-diabetic groups except for fasting plasma glucose and HbA1c levels. The average of r-CBF in each region of cerebrum and cerebellum was significantly lower in diabetic group than that in the control group (p<0.01). These observations show that r-CBF of diabetic patients is reduced, even in the absence of findings of CVD on a CT study. (author)

  16. Regional cerebral blood flow in diabetic patients

    Energy Technology Data Exchange (ETDEWEB)

    Nagamachi, Shigeki; Ono, Shinnichi; Nishikawa, Takushi (Nichinan Hospital of Miyazaki Prefecture (Japan)) (and others)

    1993-02-01

    N-isopropyl-p-[sup 123]I-iodoamphetamine (IMP) was used to quantify the regional cerebral blood flow (r-CBF) in 11 diabetic patients (average age; 67.9 years) and 12 non-diabetic subjects (average age; 67.4 years), none of whom had (cerebrovascular disease (CVD) on CT studies). A reference sampling method by continuous arterial blood sampling was used to quantify r-CBF. There were no significant differences in physiological or laboratory data between diabetic and non-diabetic groups except for fasting plasma glucose and HbA[sub 1c] levels. The average of r-CBF in each region of cerebrum and cerebellum was significantly lower in diabetic group than that in the control group (p<0.01). These observations show that r-CBF of diabetic patients is reduced, even in the absence of findings of CVD on a CT study. (author).

  17. Capillary pericytes regulate cerebral blood flow in health and disease

    DEFF Research Database (Denmark)

    Hall, Catherine N; Reynell, Clare; Gesslein, Bodil;

    2014-01-01

    Increases in brain blood flow, evoked by neuronal activity, power neural computation and form the basis of BOLD (blood-oxygen-level-dependent) functional imaging. Whether blood flow is controlled solely by arteriole smooth muscle, or also by capillary pericytes, is controversial. We demonstrate...... blood flow, capillaries dilate before arterioles and are estimated to produce 84% of the blood flow increase. In pathology, ischaemia evokes capillary constriction by pericytes. We show that this is followed by pericyte death in rigor, which may irreversibly constrict capillaries and damage the blood-brain...

  18. Photoacoustic monitoring and imaging of blood vessels in tissue

    Science.gov (United States)

    Kolkman, Roy G. M.; Pilatou, Magdalena C.; Steenbergen, Wiendelt; de Mul, Frits F. M.

    2002-06-01

    Using very sensitive photoacoustical detectors we localized and monitored the blood content in tissue. In these detectors a PVdF-layer has been used as piezo-electric material and also fibers for the illumination of the sample are integrated. The resolution is about 20micrometers in depth and about 50-100micrometers laterally. The wavelengths of the laser light were 532 and 1064 nm. With these colors we can measure at different depths in tissue. The measurements concerned blood perfusion in real tissue: vessels in chicken breast, in test animals at various positions and in the human arm.

  19. Subcutaneous blood flow during insulin-induced hypoglycaemia

    DEFF Research Database (Denmark)

    Hilsted, J; Madsbad, S; Sestoft, L

    1982-01-01

    Subcutaneous blood flow was measured preceding insulin-induced hypoglycaemia, at the onset of hypoglycaemic symptoms and 2 h later in juvenile diabetics with and without autonomic neuropathy and in normal males. In all groups subcutaneous blood flow decreased at the onset of hypoglycaemic symptoms...... compared with pre-hypoglycaemic flow. Two hours after onset of hypoglycaemic symptoms, subcutaneous blood flow was still significantly decreased compared with pre-hypoglycaemic flow. In normal subjects local nerve blockade had no effect on blood flow changes during hypoglycaemia, whereas local alpha...

  20. Renal cortical and medullary blood flow responses to altered NO availability in humans

    DEFF Research Database (Denmark)

    Damkjær, Mads; Vafaee, Manoucher; Møller, Michael L;

    2010-01-01

    , tissue layers with a thickness of one voxel were eliminated stepwise from the external surface of the VOI (voxel peeling), and the blood flow subsequently was determined in each new, reduced VOI. Blood flow in the shrinking VOIs decreased as the number of cycles of voxel peeling increased. After 4......-5 cycles, blood flow was not reduced further by additional voxel peeling. This volume-insensitive flow was measured to be 2.30 ± 0.17 ml·g tissue(-1)·min(-1) during the control period; it increased during infusion of glyceryl nitrate to 2.97 ± 0.18 ml·g tissue(-1)·min(-1) (P

  1. Role of the blood transfusion service in tissue banking.

    Science.gov (United States)

    Warwick, R M; Eastlune, T; Fehily, D

    1996-01-01

    Tissue transplantation and banking are rapidly growing services throughout the world reflecting the widening availability of transplantable cadaver tissue and the mounting clinical indications particularly in orthopaedic, plastic and cardiovascular surgery. In the US tissue banking is more established, yet continues to show a rapid growth profile. In the UK it is currently organised in a variety of different ways and by a number of different organisations. The risks of disease transmission by tissue transplantation are similar to those for blood transfusion and the majority of tissues are grafted during procedures that are not life saving. The danger of disease transmission has resulted in the introduction of legislation in the US which allows the FDA to inspect tissue banks and to recall and destroy tissues. In the UK, there is currently no regulation or inspection of tissue banks to demonstrate that donor selection, tissue processing and tracking are conducted to acceptable standards. Blood transfusion services in the UK, US, New Zealand, Australia and possibly other countries have extended their roles to include organ and tissue donation to varying degrees, with the collection, processing and distribution of bone and tendon allografts most commonly undertaken. They have readily available special capabilities and experience with an established infrastructure, compliant with Good Manufacturing Practice, placing them in an ideal position to provide this service safely and cost-effectively.

  2. Palmar skin blood flow and temperature responses throughout endoscopic sympathectomy.

    Science.gov (United States)

    Crandall, Craig G; Meyer, Dan M; Davis, Scott L; Dellaria, Suzanne M

    2005-01-01

    Thoracic surgical sympathectomy is often performed to treat primary palmar and axillary hyperhidrosis. An increase in palmar skin temperature is frequently used to identify the success of the procedure. Because changes in palmar skin temperature occur secondary to changes in skin blood flow, the objective of this study was to test the hypothesis that monitoring palmar skin blood flow would provide greater temporal resolution relative to monitoring palmar skin temperature. In 11 patients with palmar and/or axillary hyperhidrosis, we measured palmar skin temperature and blood flow (via laser Doppler flowmetry) throughout the sympathectomy procedure. Five minutes after the initial cautery, skin blood flow increased from 48 +/- 7 perfusion units to 121 +/- 17 perfusion units (P 0.05). The time required to reach peak skin blood flow (22 +/- 3 min) was significantly less than the time required to reach peak skin temperature (34 +/- 0.3 min; P <0.001). Finally at 5, 10, and 15 min after the initial cautery, skin blood flow increased to a larger percentage of the total increase in skin blood flow relative skin temperature (all P <0.006). These data suggest that monitoring skin blood flow provides greater temporal resolution when compared with monitoring skin temperature during thoracic sympathectomy. However, the initial cautery of the parietal pleura over the ganglion may result in increases in skin blood flow before physical disruption of the ganglion. This occurrence may limit the utility of skin blood-flow measurements in identifying the success of the procedure. PMID:15616091

  3. Holographic laser Doppler imaging of microvascular blood flow

    CERN Document Server

    Magnain, C; Boucneau, T; Simonutti, M; Ferezou, I; Rancillac, A; Vitalis, T; Sahel, J A; Paques, M; Atlan, M

    2014-01-01

    We report on local superficial blood flow monitoring in biological tissue from laser Doppler holographic imaging. In time averaging recording conditions, holography acts as a narrowband bandpass filter, which, combined with a frequency shifted reference beam, permits frequency selective imaging in the radiofrequency range. These Doppler images are acquired with an off axis Mach Zehnder interferometer. Microvascular hemodynamic components mapping is performed in the cerebral cortex of the mouse and the eye fundus of the rat with near-infrared laser light without any exogenous marker. These measures are made from a basic inverse method analysis of local first order optical fluctuation spectra at low radiofrequencies, from 0 Hz to 100 kHz. Local quadratic velocity is derived from Doppler broadenings induced by fluid flows, with elementary diffusing wave spectroscopy formalism in backscattering configuration. We demonstrate quadratic mean velocity assessment in the 0.1 to 10 millimeters per second range in vitro ...

  4. Skin temperature and subcutaneous adipose blood flow in man

    DEFF Research Database (Denmark)

    Astrup, A; Bülow, J; Madsen, J

    1980-01-01

    correlation between skin temperature and ATBF. In the range from 25 to 37 degrees CATBF increased 9% of the control flow on average per centigrade increase in skin temperature. ATBF at the control side was uninfluenced by the contralateral variations in skin temperature. Although no better correlation could......The abdominal subcutaneous adipose tissue blood flow (ATBF) was measured bilaterally by the 133Xe washout method. At one side of the skin (epicutaneous) temperature was varied with a temperature blanket, the other side served as control. There was a significant (P less than 0.001) positive...... be demonstrated between ATBF and subcutaneous temperature than between ATBF and skin temperature, arguments are presented in favour of the hypothesis that ATBF is influenced by the subcutaneous temperature rather than via reflexes from the skin. Infiltration of the 133Xe depots with 20 microgram...

  5. The effect of 0.5% ropivacaine on epidural blood flow

    DEFF Research Database (Denmark)

    Dahl, J B; Simonsen, L; Mogensen, T;

    1990-01-01

    Twenty patients scheduled for elective abdominal surgery received epidural analgesia with 20 ml 0.5% ropivacaine or 0.5% bupivacaine. Epidural blood flow was measured by an epidural 133Xe clearance technique on the day before surgery (no local anaesthetic) and again 1 h before surgery, 30 min after...... injection of the local anaesthetic during continuous infusion (8 ml/h). Median initial blood flow was 5.0 ml/min and 6.0 ml/min per 100 g tissue in patients receiving ropivacaine and bupivacaine, respectively. After epidural bupivacaine, blood flow increased in 8 of 10 patients to 6.9 ml/min per 100 g...

  6. Effects of inspiratory resistance, inhaled beta-agonists and histamine on canine tracheal blood flow

    Energy Technology Data Exchange (ETDEWEB)

    Kelly, W.T.; Baile, E.M.; Brancatisano, A.; Pare, P.D.; Engel, L.A. (Dept. of Respiratory Medicine, Westmead Hospital, Westmead, NSW (Australia))

    1992-01-01

    Tracheobronchial blood flow is potentially important in asthma as it could either influence the clearance of mediators form the airways, thus affecting the duration and severity of bronchoispasm, or enhance oedema formation with a resultant increase in airflow obstruction. In anaesthetized dogs, spontaneously breathing via a tracheostomy, we investigated the effects of three interventions which are relevant to acute asthma attacks and could potentially influence blood flow and its distribution to the mucosa and remaining tissues of the trachea: (1) increased negative intrathoracic pressure swings (-25[+-]1 cmH[sub 2]O) induced by an inspiratory resistance; (2) variable inhaled doses of a beta-adrenoceptor-agonist (terbutaline); and (3) aerosolized histamine sufficient to produce a threefold increase in pulmonary resistance. Microspheres labelled with different radioisotopes were used to measure blood flow. Resistive breathing did not influence tracheobronchial blood flow. Following a large dose of terbutaline, mucosal blood flow (Qmb) increased by 50%. After inhaled histamine, Qmb reached 265% of the baseline value. We conclude that, whereas increased negative pressure swings do not influence tracheobronchial blood flow or its distribution, inhalation of aerosolized terbutaline, corresponding to a conventionally nebulized dose, increases mucosal blood flow. Our results also confirm that inhaled histamine, in a dose sufficient to produce moderate bronchoconstriction, increases tracheal mucosal blood flow in the area of deposition. (au).

  7. Topical menthol increases cutaneous blood flow.

    Science.gov (United States)

    Craighead, Daniel H; Alexander, Lacy M

    2016-09-01

    Menthol, the active ingredient in several topically applied analgesics, activates transient receptor potential melastatin 8 (TRPM8) receptors on sensory nerves and on the vasculature inducing a cooling sensation on the skin. Ilex paraguariensis is also a common ingredient in topical analgesics that has potential vasoactive properties and may alter the mechanisms of action of menthol. We sought to characterize the microvascular effects of topical menthol and ilex application and to determine the mechanism(s) through which these compounds may independently and combined alter cutaneous blood flow. We hypothesized that menthol would induce vasoconstriction and that ilex would not alter skin blood flow (SkBF). Three separate protocols were conducted to examine menthol and ilex-mediated changes in SkBF. In protocol 1, placebo, 4% menthol, 0.7% ilex, and combination menthol+ilex gels were applied separately to the skin and red cell flux was continuously measured utilizing laser speckle contrast imaging (LSCI). In protocol 2, seven concentrations of menthol gel (0.04%, 0.4%, 1%, 2%, 4%, 7%, 8%) were applied to the skin to model the dose-response curve. In protocol 3, placebo, menthol, ilex, and menthol+ilex gels were applied to skin under local thermal control (34°C) both with and without sensory nerve blockage (topical lidocaine 4%). Post-occlusive reactive hyperemia (PORH) and local heating (42°C) protocols were conducted to determine the relative contribution of endothelium derived hyperpolarizing factors (EDHFs)/sensory nerves and nitric oxide (NO), respectively. Red cell flux was normalized to mean arterial pressure expressed as cutaneous vascular conductance (CVC: flux·mmHg(-1)) in all protocols. Topical menthol application increased SkBF compared to placebo (3.41±0.33 vs 1.1±0.19CVC: peffect, p<0.05) with an ED50 of 1.0%. Similarly, SkBF was increased after menthol application during PORH (3.62±0.29 vs. 2.50±0.21flux·mmHg(-1); p<0.001), but not local heating

  8. Laser Doppler measurement of cutaneous blood flow

    International Nuclear Information System (INIS)

    Laser Doppler velocimetry is an instrument system which has only recently been applied to the evaluation and quantitation of perfusion in the micro-vascular bed. The instrument is based on the Doppler principle, but uses low power laser light rather than the more commonly used ultrasound, and has a sample volume of approximately 1 mm/sup 3/. As it is non-invasive, it can be used on any skin surface or exposed microvascular bed and provides a continuous semi-quantitative measure of microcirculatory perfusion, it has a number of advantages as compared to other cutaneous blood flow measurement techniques. Initial studies have shown that it is easily used, and it has demonstrated good correlation with both xenon radio-isotope clearance and microsphere deposition techniques. Areas of current evaluation and utilization are in most major areas of medicine and surgery and include plastic, vascular and orthopaedic surgery, dermatology, gastro-enterology, rheumatology, burns and anaesthesiology

  9. Cerebral blood flow and metabolism during sleep

    DEFF Research Database (Denmark)

    Madsen, Peter Lund; Vorstrup, S

    1991-01-01

    A review of the current literature regarding sleep-induced changes in cerebral blood flow (CBF) and cerebral metabolic rate (CMR) is presented. Early investigations have led to the notion that dreamless sleep was characterized by global values of CBF and CMR practically at the level of wakefulness......, while rapid eye movement (REM) sleep (dream sleep) was a state characterized by a dramatically increased level of CBF and possibly also of CMR. However, recent investigations firmly contradict this notion. Investigations on CBF and CMR performed during non-REM sleep, taking the effect of different...... levels of sleep into consideration, show that light sleep (stage II) is characterized by global levels of CBF and CMR only slightly reduced by 3-10% below the level associated with wakefulness, whereas CBF and CMR during deep sleep (stage III-IV) is dramatically reduced by 25-44%. Furthermore, recent...

  10. Quantification of blood perfusion using 3D power Doppler: an in-vitro flow phantom study

    Energy Technology Data Exchange (ETDEWEB)

    Raine-Fenning, N J [School of Human Development, Queens Medical Centre, University of Nottingham, Nottingham (United Kingdom); Ramnarine, K V [Department of Medical Physics, University Hospitals of Leicester NHS Trust, Leicester (United Kingdom); Nordin, N M [School of Human Development, Queens Medical Centre, University of Nottingham, Nottingham (United Kingdom); Campbell, B K [School of Human Development, Queens Medical Centre, University of Nottingham, Nottingham (United Kingdom)

    2004-01-01

    Three-dimensional (3D) power Doppler data is increasingly used to assess and quantify blood flow and tissue perfusion. The objective of this study was to assess the validity of common 3D power Doppler 'vascularity' indices by quantification in well characterised in-vitro flow models. A computer driven gear pump was used to circulate a steady flow of a blood mimicking fluid through various well characterised flow phantoms to investigate the effect of the number of flow channels, flow rate, depth dependent tissue attenuation, blood mimic scatter particle concentration and ultrasound settings. 3D Power Doppler data were acquired with a Voluson 530D scanner and 7.5 MHz transvaginal transducer (GE Kretz). Virtual Organ Computer-aided Analysis software (VOCAL) was used to quantify the vascularisation index (VI), flow index (FI) and vascularisation-flow index (VFI). The vascular indices were affected by many factors, some intuitive and some with more complex or unexpected relationships (e.g. VI increased linearly with an increase in flow rate, blood mimic scatter particle concentration and number of flow channels, and had a complex dependence on pulse repetition frequency). Use of standardised settings and appropriate calibration are required in any attempt at relating 'vascularity indices' with flow.

  11. Data adaptive estimation of transversal blood flow velocities

    DEFF Research Database (Denmark)

    Pirnia, E.; Jakobsson, A.; Gudmundson, E.;

    2014-01-01

    The examination of blood flow inside the body may yield important information about vascular anomalies, such as possible indications of, for example, stenosis. Current Medical ultrasound systems suffer from only allowing for measuring the blood flow velocity along the direction of irradiation...... the transversal blood flow. In this paper, we propose a novel data-adaptive blood flow estimator exploiting this modulation scheme. Using realistic Field II simulations, the proposed estimator is shown to achieve a notable performance improvement as compared to current state-of-the-art techniques....

  12. Xenon tissue/blood partition coefficient for pig urinary bladder

    DEFF Research Database (Denmark)

    Nielsen, K K; Bülow, J; Nielsen, S L;

    1990-01-01

    In four landrace pigs the tissue/blood partition coefficient (lambda) for xenon (Xe) for the urinary bladder was calculated after chemical analysis for lipid, water and protein content and determination of the haematocrit. The coefficients varied from bladder to bladder owing to small differences...

  13. Integrated Measurements of Electrical Activity, Oxygen Tension, Blood Flow, and Ca2+ -Signaling in Rodents In Vivo

    DEFF Research Database (Denmark)

    Mathiesen, Claus; Thomsen, Kirsten; Lauritzen, Martin

    2014-01-01

    in rodent preparation. We also describe methods for recording of cerebral blood flow (CBF), tissue partial pressure of oxygen (tpO2), and cytosolic calcium transients. We finally give examples where electrophysiology, blood flow, metabolism, and calcium transients have been studied together....

  14. Cerebellar blood flow in methylmercury poisoning (Minamata disease)

    International Nuclear Information System (INIS)

    We looked at regional cerebellar blood flow in patients with Minamata disease (MD) using technetium-99 m ethyl cysteinate dimer (99m-Tc-ECD). We carried out single-photon emission computed tomography (SPECT) on 15 patients with MD (eight men, seven women, aged 51-78 years, mean 70.5 years) and 11 control subjects (eight men, three women, aged 62-80 years, mean 72.5 years). Regional blood flow was measured in the superior, middle, and inferior portions of the cerebellar hemispheres, and the frontal, temporal and occipital cerebral lobes. The degree of cerebellar atrophy was assessed on MRI. There were significant differences in regional blood flow in all parts of the cerebellum between patients and control, but no significant decrease was observed in the cerebrum. Blood flow was lower in the inferior cerebellum than in the other parts. Even in patients without cerebellar atrophy, flow was significantly decreased regional blood flow in the inferior part. (orig.)

  15. Full-field laser Doppler imaging and its physiological significance for tissue blood perfusion

    Science.gov (United States)

    Binzoni, T.; Van DeVille, D.

    2008-12-01

    Using Monte Carlo simulations for a semi-infinite medium representing a skeletal muscle tissue, it is demonstrated that the zero- and first-order moments of the power spectrum for a representative pixel of a full-field laser-Doppler imager behave differently from classical laser-Doppler flowmetry. In particular, the zero-order moment has a very low sensitivity to tissue blood volume changes, and it becomes completely insensitive if the probability for a photon to interact with a moving red blood cell is above 0.05. It is shown that the loss in sensitivity is due to the strong forward scatter of the propagating photons in biological tissues (i.e., anisotropy factor g = 0.9). The first-order moment is linearly related to the root mean square of the red blood cell velocity (the Brownian component), and there is also a positive relationship with tissue blood volume. The most common physiological interpretation of the first-order moment is as tissue blood volume times expectation of the blood velocity (in probabilistic terms). In this sense, the use of the first-order moment appears to be a reasonable approach for qualitative real-time blood flow monitoring, but it does not allow us to obtain information on blood velocity or volume independently. Finally, it is shown that the spatial and temporal resolution trade-off imposed by the CMOS detectors, used in full-field laser-Doppler hardware, may lead to measurements that vary oppositely with the underlying physiological quantities. Further improvements on detectors' sampling rate will overcome this limitation.

  16. Photoacoustic imaging of blood perfusion in tissue and phantoms

    Science.gov (United States)

    Pilatou, Magdalena C.; Kolkman, Roy G. M.; Hondebrink, Erwin; Bolt, Rene A.; de Mul, Frits F. M.

    2001-06-01

    To localize and monitor the blood content in tissue we developed a very sensitive photo-acoustical detector. PVDF has been used as piezo-electric material. In this detector also fibers for the illumination of the sample are integrated. Resolution is about 20 (m in depth and about 50-100 m laterally). We use 532 nm light. We will show how photoacoustics can be used for measuring the thickness of tissue above bone. We will also report measurements on tissue phantoms: e.g. a vessel delta from the epigastric artery branching of a Wistar rat, filled with an artificial blood-resembling absorber. The measurements have been carried out on phantoms containing vessels at several depths. Signal processing was enhanced by Fourier processing of the data.

  17. Measurement of regional cerebral blood flow by positron emission tomography

    International Nuclear Information System (INIS)

    The principal advantage of positron emission tomography over other methods for measuring cerebral blood flow stems from the accurate, quantitative three-dimensional measurements of regional brain radioactivity that are possible with this technique. As a result, accurate quantitative measurements of regional cerebral blood flow can be obtained for both superficial and deep cerebral structures. The value of PET for investigating central nervous system physiology and pathology extends far beyond this, however. Through the use of different radiotracers and appropriate mathematical models, PET can be applied to the measurement of a wide variety of physiologic variables. Measurements of rCBF tell only part of the story. Experience with PET and with a variety of other techniques has taught us that rCBF is at times a poor indicator of the metabolic, functional, and biochemical status of cerebral tissue. It is only by understanding the interaction of all of these factors that our understanding of neurologic disease can advance. It is in the investigation of these complex relationships that the real value of PET resides

  18. Blood Flow Restricted Exercise and Vascular Function

    Directory of Open Access Journals (Sweden)

    Masahiro Horiuchi

    2012-01-01

    Full Text Available It is established that regular aerobic training improves vascular function, for example, endothelium-dependent vasodilatation and arterial stiffness or compliance and thereby constitutes a preventative measure against cardiovascular disease. In contrast, high-intensity resistance training impairs vascular function, while the influence of moderate-intensity resistance training on vascular function is still controversial. However, aerobic training is insufficient to inhibit loss in muscular strength with advancing age; thus, resistance training is recommended to prevent sarcopenia. Recently, several lines of study have provided compelling data showing that exercise and training with blood flow restriction (BFR leads to muscle hypertrophy and strength increase. As such, BFR training might be a novel means of overcoming the contradiction between aerobic and high-intensity resistance training. Although it is not enough evidence to obtain consensus about impact of BFR training on vascular function, available evidences suggested that BFR training did not change coagulation factors and arterial compliance though with inconsistence results in endothelial function. This paper is a review of the literature on the impact of BFR exercise and training on vascular function, such as endothelial function, arterial compliance, or other potential factors in comparison with those of aerobic and resistance training.

  19. Regional cerebral blood flow in neuropediatrics

    International Nuclear Information System (INIS)

    Single photon emission computed tomography can effectively and non-invasively measure regional blood flow. Mostly used 99mTc-HMPAO is a safe brain imaging agent for pediatric applications. The radiation dose is acceptable. Knowledge of the normal rCBF pattern, including normal asymmetries and variations due to age, is necessary prerequisite for the evaluation and reporting of the results of 99mTc-HMPAO brain SPECT studies in clinical practice. The interpretation of he rCBF study in a child requires knowledge of normal brain maturation. The aim of the present review is to focus on the contribution to clinical developmental neurology of SPECT The clinical use of SPECT in developmental neurology are epilepsy, brain death, acute neurological loss including stroke, language disorders, cerebral palsy, high-risk neonates, hypertension due to renovascular disease, traumatic brain injury, migraine, anorexia nervosa, autism, Gilles de la Tourette syndrome, attention deficit disorder-hyperactivity, and monitoring therapy. Sedation is not routinely used, rather each child is evaluated. However, drug sedation is mandatory in some uncooperative children. (author)

  20. Pulsatile blood flow in Abdominal Aortic Aneurysms

    Science.gov (United States)

    Salsac, Anne-Virginie; Lasheras, Juan C.; Singel, Soeren; Varga, Chris

    2001-11-01

    We discuss the results of combined in-vitro laboratory measurements and clinical observations aimed at determining the effect that the unsteady wall shear stresses and the pressure may have on the growth and eventual rupturing of an Abdominal Aortic Aneurysm (AAA), a permanent bulging-like dilatation occurring near the aortic bifurcation. In recent years, new non-invasive techniques, such as stenting, have been used to treat these AAAs. However, the development of these implants, aimed at stopping the growth of the aneurysm, has been hampered by the lack of understanding of the effect that the hemodynamic forces have on the growth mechanism. Since current in-vivo measuring techniques lack the precision and the necessary resolution, we have performed measurements of the pressure and shear stresses in laboratory models. The models of the AAA were obtained from high resolution three-dimensional CAT/SCANS performed in patients at early stages of the disease. Preliminary DPIV measurements show that the pulsatile blood flow discharging into the cavity of the aneurysm leads to large spikes of pressure and wall shear stresses near and around its distal end, indicating a possible correlation between the regions of high wall shear stresses and the observed location of the growth of the aneurysm.

  1. Regional cerebral blood flow in focal cortical epilepsy

    DEFF Research Database (Denmark)

    Hougaard, Kristina Dupont; Oikawa, T; Sveinsdottir, E;

    1976-01-01

    Regional cerebral blood flow (rCBF) was studied in ten patients with focal cortical epilepsy. The blood flow was measured by the intra-arterial injection of xenon 133 (133Xe), and the isotope clearance was recorded by a multidetector scintillation camera with 254 detectors. Three patients were...

  2. Blood flow velocity in migraine attacks - a transcranial Doppler study

    Energy Technology Data Exchange (ETDEWEB)

    Zwetsloot, C.P.; Caekebeke, J.F.V.; Jansen, J.C.; Odink, J.; Ferrari, M.D. (Rijksuniversiteit Leiden (Netherlands))

    1991-05-01

    A pulsed Doppler device was used to measure blood flow velocities in the common carotid artery, the extracranial part of the internal carotid artery, the external carotid artery, the middle cerebral artery, and the anterior cerebral artery in 31 migraneurs without aura (n=27) and with aura (n=4), both during and ouside an attack. The aims were to compare blood flow velocity during and between migraine attacks and to study asymmetries of the blood flow velocity. Compared with blood flow velocity values obtained in the attack-free interval, blood flow velocity was lower during attacks without aura in both common carotid arteries, but not in the other extra- and intracranial vessels which were examined. However, during attacks of migraine with aura, blood flow velocity tended to be lower in all examined vessels. There were no asymmetries of the blood flow velocity. It is suggested that during migraine attacks without aura there is a dissociation in blood flow regulation in the common carotid and middle cerebral arteries. 20 refs., 2 tabs.

  3. Nephron blood flow dynamics measured by laser speckle contrast imaging

    DEFF Research Database (Denmark)

    von Holstein-Rathlou, Niels-Henrik; Sosnovtseva, Olga V; Pavlov, Alexey N;

    2011-01-01

    Tubuloglomerular feedback (TGF) has an important role in autoregulation of renal blood flow and glomerular filtration rate (GFR). Because of the characteristics of signal transmission in the feedback loop, the TGF undergoes self-sustained oscillations in single-nephron blood flow, GFR, and tubula...

  4. Glial and neuronal control of brain blood flow

    DEFF Research Database (Denmark)

    Attwell, David; Buchan, Alastair M; Charpak, Serge;

    2010-01-01

    Blood flow in the brain is regulated by neurons and astrocytes. Knowledge of how these cells control blood flow is crucial for understanding how neural computation is powered, for interpreting functional imaging scans of brains, and for developing treatments for neurological disorders. It is now...

  5. Blood flow measurement using a highly filled carbon polymer sandwich sensor and an elasto-pseudo compressible vascular flow.

    Science.gov (United States)

    Mehdian, M; Rahnejat, H

    1996-01-01

    Vascular grafts are widely employed in clinical practice and still pose significant problems of compatibility and longevity, particularly when the prosthesis is to replace arteries of small diameter. Once a graft has been implanted in the vascular tree, there is no easy way of assessing its interactions with the surrounding tissue. Doppler flow probes or some imaging techniques are commonly used to monitor flow velocity in vascular prostheses. It is, however, difficult to monitor a patient's recovery on a continuous basis. Continuous means of measurement can be quite invaluable. This paper presents a high-carbon filled polymer (HCFP) sensor that is developed for blood flow measurement in vascular grafts. Furthermore, a computational fluid dynamics model of incompressible blood flow in elastic blood vessels is presented. PMID:9046189

  6. Regional blood flow during exercise in humans measured by near-infrared spectroscopy and indocyanine green

    DEFF Research Database (Denmark)

    Boushel, R; Langberg, Henning; Olesen, J;

    2000-01-01

    Using near-infrared spectroscopy (NIRS) and the tracer indocyanine green (ICG), we quantified blood flow in calf muscle and around the Achilles tendon during plantar flexion (1-9 W). For comparison, blood flow in calf muscle was determined by dye dilution in combination with magnetic resonance...... imaging measures of muscle volume, and, for the peritendon region, blood flow was measured by (133)Xe washout. From rest to a peak load of 9 W, NIRS-ICG blood flow in calf muscle increased from 2.4+/-0.2 to 74+/-5 ml x 100 ml tissue(-1) x min(-1), similar to that measured by reverse dye (77+/-6 ml x 100...

  7. Lattice BGK Simulations of the Blood Flow in Elastic Vessels

    Institute of Scientific and Technical Information of China (English)

    LU Xiao-Yang; YI Hou-Hui; CHEN Ji-Yao; FANG Hai-Ping

    2006-01-01

    @@ The lattice Boltzmann method is applied to study the flow in elastic blood vessels. The volume-flow rate increases considerably when the compliance constant of the blood vessel is below a critical value. There is a region of the compliance constant in which the average volume-flow rate is dramatically enhanced. A harmonic perturbation of the pressure does not change the behaviour of the average volume-flow rate while the harmonic wave attenuates very quickly along the tube when the resonant period is close to that of the input wave. The model, together with the simulation results, is expected to be helpful to understand the mechanism of the blood volume-flow rate related to the compliance constant of the blood vessel, especially on the dependence of the flux of human blood vessel under weather changes, which has medical significance.

  8. Mammary blood flow regulation in the nursing rabbit

    Energy Technology Data Exchange (ETDEWEB)

    Katz, M.; Creasy, R.K.

    1984-11-01

    Cardiac output and mammary blood flow distribution prior to and after suckling were studied in 10 nursing rabbits by means of radionuclide-labeled microspheres. Suckling was followed by a 5.8% rise in cardiac output and a 20.4% rise in mammary blood flow. Determinations of intraglandular blood flow distribution have shown that there was a 43% increase in blood flow to the glands suckled from as compared to a 22.7% rise to the contralateral untouched glands and a 4.9% rise in the remainder of untouched glands. The conclusion is that a local mechanism may be involved in the regulation of mammary blood flow in the nursing rabbit.

  9. Design and Simulation of Axial Flow Maglev Blood Pump

    OpenAIRE

    Huachun Wu; Ziyan Wang; Xujun Lv

    2011-01-01

    The axial flow maglev blood pump (AFMBP) has become a global research focus and emphasis for artificial ventricular assist device, which has no mechanical contact, mechanical friction, compact structure and light weight, can effectively solve thrombus and hemolysis. Magnetic suspension and impeller is two of the important parts in the axial flow maglev blood pump, and their structure largely determines the blood pump performance. The research adopts electromagnetic and fluid finite element an...

  10. MUSCLE METABOLISM WITH BLOOD FLOW RESTRICTION IN CHRONIC FATIGUE SYNDROME

    OpenAIRE

    McCully, Kevin K; Smith, Sinclair; Rajaei, Sheeva; Leigh, John S.; Natelson, Benjamin H

    2003-01-01

    The purpose of this study was to determine if chronic fatigue syndrome (CFS) is associated with reduced blood flow and muscle oxidative metabolism. Patients with CFS according to CDC criteria (n=19) were compared to normal sedentary subjects (n = 11). Muscle blood flow was measured in the femoral artery with Doppler ultrasound after exercise. Muscle metabolism was measured in the medial gastrocnemius muscle using 31P magnetic resonance spectroscopy (MRS). Muscle oxygen saturation and blood vo...

  11. PERFORMANCE MODELING AND ANALYSIS OF BLOOD FLOW IN ELASTIC ARTERIES

    Institute of Scientific and Technical Information of China (English)

    Anil Kumar; C.L. Varshney; G.C. Sharma

    2005-01-01

    Two different non-Newtonian models for blood flow are considered, first a simple power law model displaying shear thinning viscosity, and second a generalized Maxwell model displaying both shear thinning viscosity and oscillating flow viscous-elasticity. These models are used along with a Newtonian model to study sinusoidal flow of blood in rigid and elastic straight arteries in the presence of magnetic field. The elasticity of blood does not appear to influence its flow behavior under physiological conditions in the large arteries,purely viscous shear thinning model should be quite realistic for simulating blood flow under these conditions. On using the power law model with high shear rate for sinusoidal flow simulation in elastic arteries, the mean and amplitude of the flow rate were found to be lower for a power law fluid compared to Newtonian fluid for the same pressure gradient. The governing equations have been solved by Crank-Niclson scheme. The results are interpreted in the context of blood in the elastic arteries keeping the magnetic effects in view. For physiological flow simulation in the aorta, an increase in mean wall shear stress, but a reduction in peak wall shear stress were observed for power law model compared to a Newtonian fluid model for matched flow rate wave form. Blood flow in the presence of transverse magnetic field in an elastic artery is investigated and the influence of factors such as morphology and surface irregularity is evaluated.

  12. The Effect of Blood Flow on Magnetic Resonance Imaging of Non Thermal Irreversible Electroporation

    Science.gov (United States)

    Hjouj, Mohammad; Lavee, Jacob; Last, David; Guez, David; Daniels, Dianne; Sharabi, Shirley; Rubinsky, Boris; Mardor, Yael

    2013-10-01

    To generate an understanding of the physiological significance of MR images of Non-Thermal Irreversible Electroporation (NTIRE) we compared the following MR imaging sequences: T1W, T2W, PD, GE, and T2 SPAIR acquired after NTIRE treatment in a rodent liver model. The parameters that were studied included the presence or absence of a Gd-based contrast agent, and in vivo and ex-vivo NTIRE treatments in the same liver. NTIRE is a new minimally invasive tissue ablation modality in which pulsed electric fields cause molecularly selective cell death while, the extracellular matrix and large blood vessels remain patent. This attribute of NTIRE is of major clinical importance as it allows treatment of undesirable tissues near critical blood vessels. The presented study results suggest that MR images acquired following NTIRE treatment are all directly related to the unique pattern of blood flow after NTIRE treatment and are not produced in the absence of blood flow.

  13. Tissue/blood partition coefficients for xenon in various adipose tissue depots in man

    DEFF Research Database (Denmark)

    Bülow, J; Jelnes, Rolf; Astrup, A;

    1987-01-01

    Tissue/blood partition coefficients (lambda) for xenon were calculated for subcutaneous adipose tissue from the abdominal wall and the thigh, and for the perirenal adipose tissue after chemical analysis of the tissues for lipid, water and protein content. The lambda in the perirenal tissue...... was found to correlate linearly to the relative body weight (RBW) in per cent with the regression equation lambda = 0.045 . RBW + 0.99. The subcutaneous lambda on the abdomen correlated linearly to the local skinfold thickness (SFT) with the equation lambda = 0.22 SFT + 2.99. Similarly lambda on the thigh...... correlated to SFT with the equation lambda = 0.20 . SFT + 4.63. It is concluded that the previously accepted lambda value of 10 is generally too high in perirenal as well as in subcutaneous tissue. Thus, by application of the present regression equations, it is possible to obtain more exact estimates...

  14. Spiral blood flow in aorta-renal bifurcation models.

    Science.gov (United States)

    Javadzadegan, Ashkan; Simmons, Anne; Barber, Tracie

    2016-01-01

    The presence of a spiral arterial blood flow pattern in humans has been widely accepted. It is believed that this spiral component of the blood flow alters arterial haemodynamics in both positive and negative ways. The purpose of this study was to determine the effect of spiral flow on haemodynamic changes in aorta-renal bifurcations. In this regard, a computational fluid dynamics analysis of pulsatile blood flow was performed in two idealised models of aorta-renal bifurcations with and without flow diverter. The results show that the spirality effect causes a substantial variation in blood velocity distribution, while causing only slight changes in fluid shear stress patterns. The dominant observed effect of spiral flow is on turbulent kinetic energy and flow recirculation zones. As spiral flow intensity increases, the rate of turbulent kinetic energy production decreases, reducing the region of potential damage to red blood cells and endothelial cells. Furthermore, the recirculation zones which form on the cranial sides of the aorta and renal artery shrink in size in the presence of spirality effect; this may lower the rate of atherosclerosis development and progression in the aorta-renal bifurcation. These results indicate that the spiral nature of blood flow has atheroprotective effects in renal arteries and should be taken into consideration in analyses of the aorta and renal arteries. PMID:26414530

  15. Blood Flow Regulation and Inflammatory Response in Experimental Models of Diabetes

    OpenAIRE

    Pettersson, Ulrika

    2012-01-01

    Type 2 diabetes is caused by defect pancreatic islet β-cells together with peripheral insulin resistance. The disease is often accompanied by obesity with associated low-grade visceral adipose tissue inflammation, which contributes to insulin resistance. As a consequence of, and a possible compensation for the increased insulin demand, blood flow to the pancreatic islets is increased in animal models of diabetes. This increased blood perfusion might with time affect the vascular network as we...

  16. ANALYSIS OF PULSATILE BLOOD FLOW IN AXIALLY MOVING ARTERIES

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    In order to study motional properties of pulsatile blood flow in axially moving arteries, the authors derived some expressions of the pulsatile blood flow from the basic equations of motion for blood and vascular walls, including an axial blood velocity equation, a flow rate equation and a wall shear stress equation, which described not only the overall axial movement of the arteries but also the elastic properties of the vascular walls, discussed the effects of the arterial wall elasticity on the wall shear stress in coronary arteries in terms of these expressions, and analyzed changes of motional properties of pulsatile blood flow between an elastic arterial tube model and a rigid tube model. The results proved the inference by J.E. Moore Jr. et al. (1994) that the axial movement of arteries be as important in determining coronary artery hemodynamics as the elastic property of the vascular wall.

  17. On the flow dependency of the electrical conductivity of blood

    NARCIS (Netherlands)

    Hoetink, AE; Faes, TJC; Visser, KR; Heethaar, RM

    2004-01-01

    Experiments presented in the literature show that the electrical conductivity of flowing blood depends on flow velocity. The aim of this study is to extend the Maxwell-Fricke theory, developed for a dilute suspension of ellipsoidal particles in an electrolyte, to explain this flow dependency of the

  18. Cerebral blood flow and metabolism during exercise: implications for fatigue

    NARCIS (Netherlands)

    N.H. Secher; T. Seifert; J.J. van Lieshout

    2008-01-01

    During exercise: the Kety-Schmidt-determined cerebral blood flow (CBF) does not change because the jugular vein is collapsed in the upright position. In contrast, when CBF is evaluated by (133)Xe clearance, by flow in the internal carotid artery, or by flow velocity in basal cerebral arteries, a app

  19. Regional blood flow in rats after a single low-protein, high-carbohydrate test meal.

    Science.gov (United States)

    Glick, Z; Wickler, S J; Stern, J S; Horwitz, B A

    1984-07-01

    It was previously observed that a single low-protein, high-carbohydrate test meal results in increased in vitro thermic activity of brown adipose tissue. In the present study, we have examined whether such a meal increases the in vivo thermic activity, estimated from measurement of the rate of blood flow. With radioactively labeled microspheres, blood flows into brown fat and several other tissues were determined in meal-deprived (n = 11) and meal-fed (n = 11) rats. The microspheres were injected into the heart of anesthetized animals about 2-2.5 h after the test meal, one injection in the resting state and one during maximal norepinephrine stimulation. In the resting state, blood flow per gram tissue more than doubled in the brown fat (P less than 0.05) and was increased more than 50% in the heart (P less than 0.01) of the fed group. Blood flows into liver and retroperitoneal white fat were reduced by 40 (P less than 0.01) and 30%, respectively, in the fed group. During norepinephrine infusion, significant meal-associated increases in blood flow were evident only in brown fat (P less than 0.05) and the soleus muscle (P less than 0.05), whereas a significant decrease was observed in the liver (P less than 0.05). No statistically significant meal-associated changes in norepinephrine-stimulated blood flow were found in the other tissues examined (i.e., heart, gastrocnemius, and diaphragm muscles, kidneys, white fat, spleen, and adrenals). Our in vivo data thus support the view that brown fat plays a role in the thermic effect of a meal. PMID:6742226

  20. Effects of non Newtonian spiral blood flow through arterial stenosis

    Science.gov (United States)

    Hasan, Md. Mahmudul; Maruf, Mahbub Alam; Ali, Mohammad

    2016-07-01

    The spiral component of blood flow has both beneficial and detrimental effects in human circulatory system. A numerical investigation is carried out to analyze the effect of spiral blood flow through an axisymmetric three dimensional artery having 75% stenosis at the center. Blood is assumed as a Non-Newtonian fluid. Standard k-ω model is used for the simulation with the Reynolds number of 1000. A parabolic velocity profile with spiral flow is used as inlet boundary condition. The peak values of all velocity components are found just after stenosis. But total pressure gradually decreases at downstream. Spiral flow of blood has significant effects on tangential component of velocity. However, the effect is mild for radial and axial velocity components. The peak value of wall shear stress is at the stenosis zone and decreases rapidly in downstream. The effect of spiral flow is significant for turbulent kinetic energy. Detailed investigation and relevant pathological issues are delineated throughout the paper.

  1. Increased bone marrow blood flow in polycythemia vera

    Energy Technology Data Exchange (ETDEWEB)

    Lathinen, R.; Lathinen, T.; Hyoedynmaa, S.

    1983-01-01

    Bone marrow blood flow was measured in polycythemia vera, in compensatory and in relative polycythemia with a /sup 133/Xe washout method. In the treated polycythemia vera bone marrow blood flow was significantly increased compared with the age-matched controls. The fraction of blood flow entering the bone and flowing through the hematopoietic marrow was markedly increased in both the untreated and the treated polycythemia vera. Although the number of observations in compensatory and relative polycythemia was small, the results suggest that bone marrow blood flow is not markedly increased in these diseases. The results also suggest that in older patients the simple /sup 133/Xe method may support the diagnosis of polycythemia vera.

  2. Diurnal variations in lower leg subcutaneous blood flow rate in patients with chronic venous leg ulcers

    DEFF Research Database (Denmark)

    Sindrup, J H; Kastrup, J; Kristensen, J K

    1991-01-01

    The blood flow rate in subcutaneous adipose tissue was measured on the lower legs of 11 patients with chronic lower-leg venous insufficiency and ulceration and in eight age-matched control subjects for 12-20 h, under ambulatory conditions, using the 133Xe wash-out technique with portable Cadmium...

  3. Regional variations in nocturnal fluctuations in subcutaneous blood flow rate in the lower leg of man

    DEFF Research Database (Denmark)

    Sindrup, J H; Kastrup, J; Jørgensen, B

    1991-01-01

    aspect of the right lower leg of normal human subjects. In the present study subcutaneous adipose tissue blood flow rates were measured simultaneously in the right and left lower legs of 16 normal human subjects over 12-20 h ambulatory conditions. The 133Xe wash-out technique, portable CdTe(Cl) detectors...

  4. Influence of the renin-angiotensin system on human forearm blood flow

    DEFF Research Database (Denmark)

    Stadeager, C; Hesse, B; Henriksen, O;

    1990-01-01

    Although angiotensin II is a potent vasoconstrictor agent in all tissues, including the human forearm, equivocal effects on forearm blood flow (FBF) have been found after angiotensin blockade. In 13 healthy Na(+)-depleted subjects FBF was measured by the 133Xe washout technique; subcutaneous and ...

  5. Combined inhibition of nitric oxide and prostaglandins reduces human skeletal muscle blood flow during exercise

    DEFF Research Database (Denmark)

    Boushel, Robert Christopher; Langberg, Henning; Gemmer, Carsten;

    2002-01-01

    The vascular endothelium is an important mediator of tissue vasodilatation, yet the role of the specific substances, nitric oxide (NO) and prostaglandins (PG), in mediating the large increases in muscle perfusion during exercise in humans is unclear. Quadriceps microvascular blood flow...

  6. INDIVIDUAL-TYPOLOGICAL FEATURES OF BLOOD FLOW AND VASCULAR REACTIVITY IN FEMALE STUDENTS

    Directory of Open Access Journals (Sweden)

    Horban D. D.

    2014-12-01

    Full Text Available The study of functional state of the microcirculation in the female body by laser Doppler flux-metry (LDF, which allows evaluating the state of the tissue blood flow and detecting signs of microcirculation changes under the influence of various factors were done. Studying individual typological features of blood circulation during recording LDF-grams in girl’s students, most of them recorded mainly of high LDF-grams with severe vasomotor waves of the second order. Parameter of microcirculation (PM of each blood flow ranged from 3.4 to 27.4 perf. ed.; on average it was 19,0 ± 0,43 perf. units. The level of tissue blood flow oscillations – SCR ranged from 0.57 to 3.23 perf. units., accounting for an average of 2,06 ± 0,05 perf. units. The coefficient of variation on average was 13,2 ± 0,51. We identified three types of LDF-grams, corresponding to different types of blood. We also determined the relationship of the thermal hyperemia with the phases of the menstrual cycle and daily dynamics of changes of microcirculation blood. Data on the peculiarities of microcirculation in female students have important theoretical and practical significance for understanding the mechanisms of regulation of tissue blood flow. The normative indicators of blood microcirculation of female students would much easier identify the functional changes in human body by using of non-invasive methods. The data on blood circulation in females can be used as standard rates of LDF measuring the study of pathological processes in medicine.

  7. Regulation of exercise blood flow: Role of free radicals.

    Science.gov (United States)

    Trinity, Joel D; Broxterman, Ryan M; Richardson, Russell S

    2016-09-01

    During exercise, oxygen and nutrient rich blood must be delivered to the active skeletal muscle, heart, skin, and brain through the complex and highly regulated integration of central and peripheral hemodynamic factors. Indeed, even minor alterations in blood flow to these organs have profound consequences on exercise capacity by modifying the development of fatigue. Therefore, the fine-tuning of blood flow is critical for optimal physical performance. At the level of the peripheral circulation, blood flow is regulated by a balance between the mechanisms responsible for vasodilation and vasoconstriction. Once thought of as toxic by-products of in vivo chemistry, free radicals are now recognized as important signaling molecules that exert potent vasoactive responses that are dependent upon the underlying balance between oxidation-reduction reactions or redox balance. Under normal healthy conditions with low levels of oxidative stress, free radicals promote vasodilation, which is attenuated with exogenous antioxidant administration. Conversely, with advancing age and disease where background oxidative stress is elevated, an exercise-induced increase in free radicals can further shift the redox balance to a pro-oxidant state, impairing vasodilation and attenuating blood flow. Under these conditions, exogenous antioxidants improve vasodilatory capacity and augment blood flow by restoring an "optimal" redox balance. Interestingly, while the active skeletal muscle, heart, skin, and brain all have unique functions during exercise, the mechanisms by which free radicals contribute to the regulation of blood flow is remarkably preserved across each of these varied target organs. PMID:26876648

  8. Regulation of exercise blood flow: Role of free radicals.

    Science.gov (United States)

    Trinity, Joel D; Broxterman, Ryan M; Richardson, Russell S

    2016-09-01

    During exercise, oxygen and nutrient rich blood must be delivered to the active skeletal muscle, heart, skin, and brain through the complex and highly regulated integration of central and peripheral hemodynamic factors. Indeed, even minor alterations in blood flow to these organs have profound consequences on exercise capacity by modifying the development of fatigue. Therefore, the fine-tuning of blood flow is critical for optimal physical performance. At the level of the peripheral circulation, blood flow is regulated by a balance between the mechanisms responsible for vasodilation and vasoconstriction. Once thought of as toxic by-products of in vivo chemistry, free radicals are now recognized as important signaling molecules that exert potent vasoactive responses that are dependent upon the underlying balance between oxidation-reduction reactions or redox balance. Under normal healthy conditions with low levels of oxidative stress, free radicals promote vasodilation, which is attenuated with exogenous antioxidant administration. Conversely, with advancing age and disease where background oxidative stress is elevated, an exercise-induced increase in free radicals can further shift the redox balance to a pro-oxidant state, impairing vasodilation and attenuating blood flow. Under these conditions, exogenous antioxidants improve vasodilatory capacity and augment blood flow by restoring an "optimal" redox balance. Interestingly, while the active skeletal muscle, heart, skin, and brain all have unique functions during exercise, the mechanisms by which free radicals contribute to the regulation of blood flow is remarkably preserved across each of these varied target organs.

  9. Organ hierarchy during low blood flow on-pump: a randomized experimental positron emission tomography study

    DEFF Research Database (Denmark)

    Thomassen, Sisse Anette; Kjærgaard, Benedict; Frøkiær, Jørgen;

    ; normothermic CPB with a blood flow of 2.5 L/min/m2 for one hour followed by a randomisation to a blood flow of either 2.0 L/min/m2 (Group I) or 1.5 L/min/m2 (Group II) for another hour and finally one hour with blood flow of 2.5 L/min/m2. Regional tissue perfusion of brain, liver, kidney, and muscle...... indicates existence of an organ hierarchy with persevered perfusion of the brain but affected muscle tissue perfusion in in both Groups of suboptimal blood flow. The finally results will be ready for presentation at DASAIM 2014 in November. Non-parametric statistical method will be used. Discussion To our...... knowledge this is the first study investigating organ hierarchy with dynamic PET-CT during profound systemic ischemia due to suboptimal blood flows during normothermic CPB. References 1. Murphy JM, Hessel II EA, Groom RC. Optimal perfusion during cardiopulmonary bypass: an Evidence-based approach. Anesth...

  10. Collateral sources of costal and crural diaphragmatic blood flow

    International Nuclear Information System (INIS)

    We measured the contribution of aortic, internal mammary, and intercostal arteries to the blood flow to the costal and crural segments of the diaphragm and other respiratory muscles in seven dogs breathing against a fixed inspiratory elastic load. We used radiolabeled microspheres to measure the blood flow with control circulation, occlusion of the aorta distal to the left subclavian artery, combined occlusion of the aorta and both internal mammary arteries, and occlusion of internal mammary arteries alone. With occlusion of the aorta distal to the left subclavian artery, blood flow to the crural diaphragm decreased from 40.3 to 23.5 ml . min-1 X 100 g-1, whereas costal flow did not change significantly (from 41.7 to 38.1 ml . min-1 . 100 g-1). Blood flows to the sternomastoid and scalene muscles (above the occlusion) increased by 200 and 340%, respectively, whereas flows to the other respiratory muscles did not change significantly. Blood flows to organs above the occlusion either remained unchanged or increased, whereas flows to those below the occlusion all decreased. When the internal mammary artery was also occluded, flows to the crural segment decreased further to 12.1 and costal flow decreased to 20.4 ml X min-1 X 100 g-1. Internal mammary arterial occlusion alone in two dogs had no effect on diaphragmatic flow. In conclusion, intercostal collateral vessels are capable of supplying a significant proportion of blood flow to both segments of the diaphragm but the costal segment is better served than the crural segment

  11. Coronary blood flow in the anesthetized American alligator (Alligator mississippiensis).

    Science.gov (United States)

    Jensen, Bjarke; Elfwing, Magnus; Elsey, Ruth M; Wang, Tobias; Crossley, Dane A

    2016-01-01

    Coronary circulation of the heart evolved early within ectothermic vertebrates and became of vital importance to cardiac performance in some teleost fish, mammals and birds. In contrast, the role and function of the coronary circulation in ectothermic reptiles remains largely unknown. Here, we investigated the systemic and coronary arterial responses of five anesthetized juvenile American alligators (Alligator mississippiensis) to hypoxia, acetylcholine, adenosine, sodium nitroprusside, isoproterenol, and phenylephrine. We recorded electrocardiograms, monitored systemic blood pressure, blood flows in both aortae, and blood flow in a major coronary artery supplying most of the right ventricle. Coronary arterial blood flow was generally forward, but there was a brief retrograde flow during a ventricular contraction. Blood pressure was significantly changed in all conditions. Acetylcholine decreased coronary forward flow, but this response was confounded by the concomitant lowered work of the ventricles due to decreased heart rate and blood pressure. Coronary forward flow was poorly correlated with heart rate and mean arterial pressure across treatments. Overall changes in coronary forward flow, significant and not significant, were generally in the same direction as mean arterial pressure and ventricular power, approximated as the product of systemic cardiac output and mean arterial pressure. PMID:26436857

  12. Low cerebral blood flow in hypotensive perinatal distress

    International Nuclear Information System (INIS)

    Hypoxic brain injury is the most important neurological problem in the neonatal period and accounts for more neurological deficits in children than any other lesion. The neurological deficits are notably mental retardation, epilepsy and cerebral palsy. The pathogenesis has hitherto been poorly understood. Arterial hypoxia has been taken as the obvious mechanism but this does not fully explain the patho-anatomical findings. In the present investigation we have examined the arterial blood pressure and the cerebral blood flow in eight infants a few hours after birth. The 133Xe clearance technique was used for the cerebral blood flow measurements. The study confirmed that perinatal distress may be associated with low arterial blood pressure, and it was shown that cerebral blood flow is very low, 20 ml/100 g/min or less, in hypotensive perinatal distress. It is concluded that cerebral ischaemia plays a crucial role in the development of perinatal hypoxic brain injury. (author)

  13. Aging, regional cerebral blood flow, and neuropsychological functioning

    International Nuclear Information System (INIS)

    Previous studies found changes in regional cerebral blood flow (rCBF) patterns related to both age and various cognitive tasks. However, no study has yet demonstrated a relationship between rCBF and performance on the Luria-Nebraska Neuropsychological Battery (LNNB) in an elderly group. Seventy-nine elderly volunteers (56-88 years old), both healthy and demented, underwent the 133xenon inhalation rCBF procedure and were given the LNNB. The decrements in the gray-matter blood flow paralleled decrements in performance on the LNNB. Using partial correlations, a significant proportion of shared variance was observed between gray-matter blood flow and the LNNB scales. However, there was much less of a relationship between white-matter blood flow and performance on the LNNB. This study suggests that even within a restricted age sample rCBF is related in a global way to neuropsychological functioning

  14. Aging, regional cerebral blood flow, and neuropsychological functioning

    Energy Technology Data Exchange (ETDEWEB)

    MacInnes, W.D.; Golden, C.J.; Gillen, R.W.; Sawicki, R.F.; Quaife, M.; Uhl, H.S.; Greenhouse, A.J.

    1984-10-01

    Previous studies found changes in regional cerebral blood flow (rCBF) patterns related to both age and various cognitive tasks. However, no study has yet demonstrated a relationship between rCBF and performance on the Luria-Nebraska Neuropsychological Battery (LNNB) in an elderly group. Seventy-nine elderly volunteers (56-88 years old), both healthy and demented, underwent the /sup 133/xenon inhalation rCBF procedure and were given the LNNB. The decrements in the gray-matter blood flow paralleled decrements in performance on the LNNB. Using partial correlations, a significant proportion of shared variance was observed between gray-matter blood flow and the LNNB scales. However, there was much less of a relationship between white-matter blood flow and performance on the LNNB. This study suggests that even within a restricted age sample rCBF is related in a global way to neuropsychological functioning.

  15. Reduced blood flow to contracting skeletal muscle in ageing humans

    DEFF Research Database (Denmark)

    Nyberg, Michael Permin; Hellsten, Ylva

    2016-01-01

    consequences of ageing and physical inactivity can be challenging; yet, observations from cross-sectional and longitudinal studies on the effects of physical activity have provided some insight. Physical activity has the potential to offset the age-related decline in blood flow to contracting skeletal muscle...... during exercise where systemic blood flow is not limited by cardiac output, thereby improving O2 delivery and allowing for an enhanced energy production from oxidative metabolism. The mechanisms underlying the increase in blood flow with regular physical activity include improved endothelial function...... the O2 demand of the active skeletal muscle of aged individuals during conditions where systemic blood flow is not limited by cardiac output seems to a large extent to be related to the level of physical activity. This article is protected by copyright. All rights reserved....

  16. Blood flow changes coincide with cellular rearrangements during blood vessel pruning in zebrafish embryos.

    Directory of Open Access Journals (Sweden)

    Eva Kochhan

    Full Text Available After the initial formation of a highly branched vascular plexus, blood vessel pruning generates a hierarchically structured network with improved flow characteristics. We report here on the cellular events that occur during the pruning of a defined blood vessel in the eye of developing zebrafish embryos. Time-lapse imaging reveals that the connection of a new blood vessel sprout with a previously perfused multicellular endothelial tube leads to the formation of a branched, Y-shaped structure. Subsequently, endothelial cells in parts of the previously perfused branch rearrange from a multicellular into a unicellular tube, followed by blood vessel detachment. This process is accompanied by endothelial cell death. Finally, we show that differences in blood flow between neighboring vessels are important for the completion of the pruning process. Our data suggest that flow induced changes in tubular architecture ensure proper blood vessel pruning.

  17. Experimental comparison of mammalian and avian blood flow in microchannels

    Science.gov (United States)

    Fink, Kathryn; Liepmann, Dorian

    2015-11-01

    The non-Newtonian, shear rate dependent behavior of blood in microchannel fluid dynamics has been studied for nearly a century, with a significant focus on the characteristics of human blood. However, for over 200 years biologists have noted significant differences in red blood cell characteristics across vertebrate species, with particularly drastic differences in cell size and shape between mammals and non-mammalian classes. We present an experimental analysis of flow in long microchannels for several varieties of mammalian and avian blood, across a range of hematocrits, channel diameters, and flow rates. Correlation of shear rate and viscosity is compared to existing constitutive equations for human blood to further quantify the importance of red blood cell characteristics. Ongoing experimental results are made available in an online database for reference or collaboration. K.F. acknowledges funding from the ARCS Foundation and an NSF Graduate Research Fellowship through NSF Grant DGE 1106400.

  18. Measuring bovine mammary gland blood flow using a transit time ultrasonic flow probe.

    Science.gov (United States)

    Gorewit, R C; Aromando, M C; Bristol, D G

    1989-07-01

    Lactating cattle were used to validate a transit time ultrasonic blood flow metering system for measuring mammary gland arterial blood flow. Blood flow probes were surgically placed around the right external pudic artery. An electromagnetic flow probe was implanted in tandem with the ultrasonic probe in two cows for comparative measurements. The absolute accuracy of the implanted flow probes was assessed in vivo by mechanical means on anesthetized cows after 2 to 3 wk of implantation. The zero offset of the ultrasonic probes ranged from -12 to 8 ml/min. When the ultrasonic probe was properly implanted, the slopes of the calibration curves were linear and ranged from .92 to .95, tracking absolute flow to within 8%. The transit time instrument's performance was examined under a variety of physiological conditions. These included milking and hormone injections. The transit time ultrasonic flow meter accurately measured physiological changes in mammary arterial blood flow in chronically prepared conscious cattle. Blood flow increased 29% during milking. Epinephrine decreased mammary blood flow by 90 to 95%. Oxytocin doses increased mammary blood flow by 15 to 24%. PMID:2674232

  19. [Evaluation on blood clearance and hepatic uptake of 99mTc-GSA in rats with blood flow conversion].

    Science.gov (United States)

    Ohno, K

    1997-05-01

    This study was aimed to clarify a contribution of the hepatic blood flow in hepatic accumulation of 99mTc-DTPA-galactosyl serum albumin (99mTc-GSA). The experiment was performed in rats by the blood flow conversion with an external scintillation gamma camera and laser doppler flowmeter. Rats were divided into 4 groups: hepatic artery ligation (HAL, n = 10), portal vein ligation (PVL, n = 8), both hepatic artery and portal vein ligation (HAL+PVL, n = 9), and control (CONT, n = 10) groups. The scintigraphic data were obtained in each group for 10 minutes after intravenous injection of 99mTc-GSA (50 micrograms/100 g B.W). The regions of interest were assigned over the heart and whole liver and the time activity curves (TAC) were generated. Five parameters of HH 4, LHL 4, KH1, KH2, KL, were calculated as blood clearance and hepatic accumulation from TAC in each rat. HH4 as blood clearance index in CONT, HAL, PVL and HAL+PVL was 0.58 +/- 0.04 (mean +/- SE), 0.63 +/- 0.04, 0.85 +/- 0.04, 0.97 +/- 0.001, respectively. HH 4 between CONT vs PVL, HAL+PVL was statistically significant (p hepatic uptake index in CONT, HAL, PVL and HAL+PVL was 0.96 +/- 0.001, 0.93 +/- 0.01, 0.71 +/- 0.07, 0.41 +/- 0.04, respectively. This parameter was also statistically significant between CONT vs PVL and HAL+PVL groups. Another parameter of KH1 for blood clearance and KL for hepatic uptake were also significant between CONT vs PVL and HAL+PVL groups. All parameters obtained in 99mTc-GSA study correlated well with the hepatic flow rate which was measured with a laser doppler flowmeter and reflected the reduction rate of the hepatic tissue blood flow 4 minutes after the ligation of target vessels. These result suggest that blood clearance and hepatic uptake of 99mTc-GSA are significantly affected by hepatic blood inflow. 99mTc-GSA scintigraphy may be useful in evaluating hepatic tissue blood flow. PMID:9226469

  20. Radiohalogenated thienylethylamine derivatives for evaluating local cerebral blood flow

    Science.gov (United States)

    Goodman, Mark M.; Knapp, Jr., Furn F.

    1990-01-01

    Radiopharmaceuticals useful in brain imaging comprising radiohalogenated thienylethylamine derivatives. The compounds are 5-halo-thiophene-2-isopropyl amines able to cross the blood-brain barrier and be retained for a sufficient length of time to allow the evaluation or regional blood flow by radioimaging of the brain.

  1. Blood flow structure in patients with coronary heart disease

    Science.gov (United States)

    Malinova, Lidia I.; Simonenko, Georgy V.; Denisova, Tatyana P.; Tuchin, Valery V.

    2007-05-01

    Blood flow structure was studied by PC integrated video camera with following slide by slide analysis. Volumetric blood flow velocity was supporting on constant level (1 ml/h). Silicone tube of diameter comparable with coronary arteries diameter was used as vessel model. Cell-cell interactions were studied under glucose and anticoagulants influence. Increased adhesiveness of blood cells to tube walls was revealed in patient with coronary heart disease (CHD) compare to practically healthy persons (PHP). In patients with stable angina pectoris of high functional class and patients with AMI shear stress resistant erythrocyte aggregates were predominating in blood flow structure up to microclots formation. Clotting and erythrocytes aggregation increase as response to glucose solution injection, sharply defined in patients with CHD. Heparin injection (10 000 ED) increased linear blood flow velocity both in patients with CHD and PHP. After compare our results with other author's data we can consider that method used in our study is sensible enough to investigate blood flow structure violations in patients with CHD and PHP. Several differences of cell-cell interaction in flow under glucose and anticoagulant influence were found out in patients with CHD and PHP.

  2. Spatiotemporal changes in blood-brain barrier permeability, cerebral blood flow, T2 and diffusion following mild traumatic brain injury.

    Science.gov (United States)

    Li, Wei; Watts, Lora; Long, Justin; Zhou, Wei; Shen, Qiang; Jiang, Zhao; Li, Yunxia; Duong, Timothy Q

    2016-09-01

    The blood-brain barrier (BBB) can be impaired following traumatic brain injury (TBI), however the spatiotemporal dynamics of BBB leakage remain incompletely understood. In this study, we evaluated the spatiotemporal evolution of BBB permeability using dynamic contrast-enhanced MRI and measured the volume transfer coefficient (K(trans)), a quantitative measure of contrast agent leakage across the blood and extravascular compartment. Measurements were made in a controlled cortical impact (CCI) model of mild TBI in rats from 1h to 7 days following TBI. The results were compared with cerebral blood flow, T2 and diffusion MRI from the same animal. Spatially, K(trans) changes were localized to superficial cortical layers within a 1mm thickness, which was dramatically different from the changes in cerebral blood flow, T2 and diffusion, which were localized to not only the superficial layers but also to brain regions up to 2.2mm from the cortical surface. Temporally, K(trans) changes peaked at day 3, similar to CBF and ADC changes, but differed from T2 and FA, whose changes peaked on day 2. The pattern of superficial cortical layer localization of K(trans) was consistent with patterns revealed by Evans Blue extravasation. Collectively, these results suggest that BBB disruption, edema formation, blood flow disturbance and diffusion changes are related to different components of the mechanical impact, and may play different roles in determining injury progression and tissue fate processes following TBI. PMID:27208495

  3. Functional Doppler optical coherence tomography for cortical blood flow imaging

    Science.gov (United States)

    Yu, Lingfeng; Liu, Gangjun; Nguyen, Elaine; Choi, Bernard; Chen, Zhongping

    2010-02-01

    Optical methods have been widely used in basic neuroscience research to study the cerebral blood flow dynamics in order to overcome the low spatial resolution associated with magnetic resonance imaging and positron emission tomography. Although laser Doppler imaging and laser speckle imaging can map out en face cortical hemodynamics and columns, depth resolution is not available. Two-photon microscopy has been used for mapping cortical activity. However, flow measurement requires fluorescent dye injection, which can be problematic. The noninvasive and high resolution tomographic capabilities of optical coherence tomography make it a promising technique for mapping depth resolved cortical blood flow. Here, we present a functional Doppler optical coherence tomography (OCT) imaging modality for quantitative evaluation of cortical blood flow in a mouse model. Fast, repeated, Doppler OCT scans across a vessel of interest were performed to record flow dynamic information with a high temporal resolution of the cardiac cycles. Spectral Doppler analysis of continuous Doppler images demonstrates how the velocity components and longitudinally projected flow-volume-rate change over time, thereby providing complementary temporal flow information to the spatially distributed flow information of Doppler OCT. The proposed functional Doppler OCT imaging modality can be used to diagnose vessel stenosis/blockage or monitor blood flow changes due to pharmacological agents/neuronal activities. Non-invasive in-vivo mice experiments were performed to verify the capabilities of function Doppler OCT.

  4. Modeling of human colonic blood flow for a novel artificial anal sphincter system

    Institute of Scientific and Technical Information of China (English)

    Peng ZAN; Guo-zheng YAN; Hua LIU

    2008-01-01

    A novel artificial anal sphincter system has been developed to simulate the normal physiology of the human anorectum. With the goal of engineering a safe and reliable device, the model of human colonic blood flow has been built and the relationship between the colonic blood flow rate and the operating occlusion pressure of the anorectum is achieved. The tissue ischemia is analyzed based on constitutive relations for human anorectum. The results suggest that at the planned operating occlusion pressure of less than 4 kPa the artificial anal sphincter should not risk the vaseularity of the human colon.

  5. Ultrafast Ultrasound Imaging of Ocular Anatomy and Blood Flow

    Science.gov (United States)

    Urs, Raksha; Ketterling, Jeffrey A.; Silverman, Ronald H.

    2016-01-01

    Purpose Ophthalmic ultrasound imaging is currently performed with mechanically scanned single-element probes. These probes have limited capabilities overall and lack the ability to image blood flow. Linear-array systems are able to detect blood flow, but these systems exceed ophthalmic acoustic intensity safety guidelines. Our aim was to implement and evaluate a new linear-array–based technology, compound coherent plane-wave ultrasound, which offers ultrafast imaging and depiction of blood flow at safe acoustic intensity levels. Methods We compared acoustic intensity generated by a 128-element, 18-MHz linear array operated in conventionally focused and plane-wave modes and characterized signal-to-noise ratio (SNR) and lateral resolution. We developed plane-wave B-mode, real-time color-flow, and high-resolution depiction of slow flow in postprocessed data collected continuously at a rate of 20,000 frames/s. We acquired in vivo images of the posterior pole of the eye by compounding plane-wave images acquired over ±10° and produced images depicting orbital and choroidal blood flow. Results With the array operated conventionally, Doppler modes exceeded Food and Drug Administration safety guidelines, but plane-wave modalities were well within guidelines. Plane-wave data allowed generation of high-quality compound B-mode images, with SNR increasing with the number of compounded frames. Real-time color-flow Doppler readily visualized orbital blood flow. Postprocessing of continuously acquired data blocks of 1.6-second duration allowed high-resolution depiction of orbital and choroidal flow over the cardiac cycle. Conclusions Newly developed high-frequency linear arrays in combination with plane-wave techniques present opportunities for the evaluation of ocular anatomy and blood flow, as well as visualization and analysis of other transient phenomena such as vessel wall motion over the cardiac cycle and saccade-induced vitreous motion. PMID:27428169

  6. Femoral Blood Flow and Cardiac Output During Blood Flow Restricted Leg Press Exercise

    Science.gov (United States)

    Everett, M. E.; Hackney, K.; Ploutz-Snyder, L.

    2011-01-01

    Low load blood flow restricted resistance exercise (LBFR) causes muscle hypertrophy that may be stimulated by the local ischemic environment created by the cuff pressure. However, local blood flow (BF) during such exercise is not well understood. PURPOSE: To characterize femoral artery BF and cardiac output (CO) during leg press exercise (LP) performed at a high load (HL) and low load (LL) with different levels of cuff pressure. METHODS: Eleven subjects (men/women 4/7, age 31.4+/-12.8 y, weight 68.9+/-13.2 kg, mean+/-SD) performed 3 sets of supine left LP to fatigue with 90 s of rest in 4 conditions: HL (%1-RM/cuff pressure: 80%/0); LL (20%/0); LBFR(sub DBP) (20%/1.3 x diastolic blood pressure, BP); LBFR(sub SBP) (20%/1.3 x supine systolic BP). The cuff remained inflated throughout the LBFR exercise sessions. Artery diameter, velocity time integral (VTI), and stroke volume (SV) were measured using Doppler ultrasound at rest and immediately after each set of exercise. Heart rate (HR) was monitored using a 3-lead ECG. BF was calculated as VTI x vessel cross-sectional area. CO was calculated as HR x SV. The data obtained after each set of exercise were averaged and used for analyses. Multi-level modeling was used to determine the effect of exercise condition on dependent variables. Statistical significance was set a priori at p LL (9.92+/-0.82 cm3) > LBFR(sub dBP)(6.47+/-0.79 cm3) > LBFR(sub SBP) (3.51+/-0.59 cm3). Blunted exercise induced increases occurred in HR, SV, and CO after LBFR compared to HL and LL. HR increased 45% after HL and LL and 28% after LBFR (p<0.05), but SV increased (p<0.05) only after HL. Consequently, the increase (p<0.05) in CO was greater in HL and LL (approximately 3 L/min) than in LBFR (approximately 1 L/min). CONCLUSION: BF during LBFR(sub SBP) was 1/3 of that observed in LL, which supports the hypothesis that local ischemia stimulates the LBFR hypertrophic response. As the cuff did not compress the artery, the ischemia may have occurred

  7. Non invasive blood flow assessment in diabetic foot ulcer using laser speckle contrast imaging technique

    Science.gov (United States)

    Jayanthy, A. K.; Sujatha, N.; Reddy, M. Ramasubba; Narayanamoorthy, V. B.

    2014-03-01

    Measuring microcirculatory tissue blood perfusion is of interest for both clinicians and researchers in a wide range of applications and can provide essential information of the progress of treatment of certain diseases which causes either an increased or decreased blood flow. Diabetic ulcer associated with alterations in tissue blood flow is the most common cause of non-traumatic lower extremity amputations. A technique which can detect the onset of ulcer and provide essential information on the progress of the treatment of ulcer would be of great help to the clinicians. A noninvasive, noncontact and whole field laser speckle contrast imaging (LSCI) technique has been described in this paper which is used to assess the changes in blood flow in diabetic ulcer affected areas of the foot. The blood flow assessment at the wound site can provide critical information on the efficiency and progress of the treatment given to the diabetic ulcer subjects. The technique may also potentially fulfill a significant need in diabetic foot ulcer screening and management.

  8. Ultrasonic Imaging of Hemodynamic Force in Carotid Blood Flow

    Science.gov (United States)

    Nitta, N.; Homma, K.

    Hemodynamic forces including blood pressure and shear stress affect vulnerable plaque rupture in arteriosclerosis and biochemical activation of endothelium such as NO production. In this study, a method for estimating and imaging shear stress and pressure gradient distributions in blood vessel as the hemodynamic force based on viscosity estimation is presented. Feasibility of this method was investigated by applying to human carotid blood flow. Estimated results of shear stress and pressure gradient distributions coincide with the ideal distributions obtained by numerical simulation and flow-phantom experiment.

  9. CHARACTERIZATION OF RENAL BLOOD FLOW REGULATION BASED ON WAVELET COEFFICIENTS

    DEFF Research Database (Denmark)

    Pavlov, A.N.; Pavlova, O.N.; Mosekilde, Erik;

    2010-01-01

    The purpose of this study is to demonstrate the possibility of revealing new characteristic features of renal blood flow autoregulation in healthy and pathological states through the application of discrete wavelet transforms to experimental time series for normotensive and hypertensive rats....... A reduction in the variability of the wavelet coefficients in hypertension is observed at both the microscopic level of the blood flow in efferent arterioles of individual nephrons and at the macroscopic level of the blood pressure in the main arteries. The reduction is manifest in both of the main frequency...

  10. ''Blood flow measurements in the irradiated pig skin using β emitters radionuclides''

    International Nuclear Information System (INIS)

    Non invasive methods of study of the skin blood flow are numerous, but generally do not give any indication on the cutaneous micro-circulatory flow, except for cutaneous laser Doppler. The isotopic exploration of the skin with injected γ radionuclides, even of weak energy, doe snot allow to characterize the skin blood flow, because of the important contribution of the subcutaneous tissues. The use of β emitters energy spectrum, analyzed by different quantitative methods, are proportional to the thickness of the screen localized between the radioactive source and detector. Using simple and complex phantoms composed of tissue equivalent screens, with 32P sources placed at different depths, it was possible to study the degradation of β spectra, simulating respectively the sub-epidermis and sub-dermis vascular levels. A modelization and an experimental study in-vivo are proposed in this work, with 32P phosphate administered intravenously in pigs. (author)

  11. Research Advances: DRPS--Let The Blood Flow!

    Science.gov (United States)

    King, Angela G.

    2007-01-01

    A team from the University of Pittsburgh's McGowan Institute for Regenerative Medicine has shown the potential for clinical use of the drag-reducing polymer (DRP) poly(N-vinylformamide), or PNVF. The high molecular weight PNVF is shown to reduce resistance to turbulent flow in a pipe and to enhance blood flow in animal models and it also…

  12. Blood Flow through an Open-Celled Foam

    Science.gov (United States)

    Ortega, Jason; Maitland, Duncan

    2011-11-01

    The Hazen-Dupuit-Darcy (HDD) equation is commonly used in engineering applications to model the pressure gradient of flow through a porous media. One major advantage of this equation is that it simplifies the complex geometric details of the porous media into two coefficients: the permeability, K, and form factor, C. However through this simplification, the flow details within the porous media are no longer accessible, making it difficult to study the phenomena that contribute to changes in K and C due to clotting of blood flow. To obtain a more detailed understanding of blood flow through a porous media, a direct assessment of the complex interstitial geometry and flow is required. In this study, we solve the Navier-Stokes equations for Newtonian and non-Newtonian blood flow through an open-celled foam geometry obtained from a micro-CT scan. The nominal strut size of the foam sample is of O(10e-5) m and the corresponding Reynolds number based upon this length ranges up to O(10). Fitting the pressure gradient vs. Darcy velocity data with the HDD equation demonstrates that both viscous and inertial forces play an important role in the flow through the foam at these Reynolds numbers. Recirculation zones are observed to form in the wake of the pore struts, producing regions of flow characterized by both low shear rates and long fluid residence times, factors of which have been shown in previous studies to promote blood clotting.

  13. A multiple disk centrifugal pump as a blood flow device.

    Science.gov (United States)

    Miller, G E; Etter, B D; Dorsi, J M

    1990-02-01

    A multiple disk, shear force, valveless centrifugal pump was studied to determine its suitability as a blood flow device. A pulsatile version of the Tesla viscous flow turbine was designed by modifying the original steady flow pump concept to produce physiological pressures and flows with the aid of controlling circuitry. Pressures and flows from this pump were compared to a Harvard Apparatus pulsatile piston pump. Both pumps were connected to an artificial circulatory system. Frequency and systolic duration were varied over a range of physiological conditions for both pumps. The results indicated that the Tesla pump, operating in a pulsatile mode, is capable of producing physiologic pressures and flows similar to the Harvard pump and other pulsatile blood pumps. PMID:2312140

  14. 75 FR 36060 - Notice of Request for Extension of Approval of an Information Collection; Blood and Tissue...

    Science.gov (United States)

    2010-06-24

    ... Collection; Blood and Tissue Collection at Slaughtering and Rendering Establishments AGENCY: Animal and Plant... collection associated with regulations for blood and tissue collection at slaughtering and rendering... FURTHER INFORMATION CONTACT: For information on regulations for blood and tissue collection...

  15. Laboratory diagnosis of infections due to blood and tissue parasites.

    Science.gov (United States)

    Rosenblatt, Jon E

    2009-10-01

    Microscopy remains the cornerstone of the laboratory diagnosis of infections due to blood and tissue parasites. Examination of thick and thin peripheral blood smears stained with Giemsa or other appropriate stains is used for detection and identification of species of Plasmodium, Babesia, Trypanosoma, Brugia, Mansonella, and Wuchereria. Even in the hands of well-trained technologists, diagnosis may be hampered by the sparseness of organisms on the slide and by the subjective nature of differentiating similar-appearing organisms. Microscopy and/or culture of ulcer, bone marrow, tissue aspirate, and biopsy samples are useful for the diagnosis of African trypanosomiasis, onchocerciasis, trichinosis, and leishmaniasis. Serologic assays are available for the diagnosis of a number of these infections, but none of these assays are sensitive or specific enough to be used on their own to establish a diagnosis. In particular, the use of assays for the diagnosis of infection with a particular helminth will often cross-react with antibodies to a different helminth. Very sensitive polymerase chain reaction assays have been developed for a number of these parasites and are available from the Centers for Disease Control and Prevention and from several referral laboratories. PMID:19691431

  16. In vivo functional imaging of blood flow and wall strain rate in outflow tract of embryonic chick heart using ultrafast spectral domain optical coherence tomography

    Science.gov (United States)

    Li, Peng; Yin, Xin; Shi, Liang; Rugonyi, Sandra; Wang, Ruikang K.

    2012-09-01

    During cardiac development, the cardiac wall and flowing blood are two important cardiac tissues that constantly interact with each other. This dynamic interaction defines appropriate biomechanical environment to which the embryonic heart is exposed. Quantitative assessment of the dynamic parameters of wall tissues and blood flow is required to further our understanding of cardiac development. We report the use of an ultrafast 1310-nm dual-camera spectral domain optical coherence tomography (SDOCT) system to characterize/image, in parallel, the dynamic radial strain rate of the myocardial wall and the Doppler velocity of the underlying flowing blood within an in vivo beating chick embryo. The OCT system operates at 184-kHz line scan rate, providing the flexibility of imaging the fast blood flow and the slow tissue deformation within one scan. The ability to simultaneously characterize tissue motion and blood flow provides a useful approach to better understand cardiac dynamics during early developmental stages.

  17. Regional cerebral blood flow during hypoxia-ischemia in immature rats

    Energy Technology Data Exchange (ETDEWEB)

    Vannucci, R.C.; Lyons, D.T.; Vasta, F.

    1988-02-01

    Immature rats subjected to a combination of unilateral common carotid artery ligation and hypoxia sustain brain damage confined largely to the ipsilateral cerebral hemisphere. To ascertain the extent and distribution of ischemic alterations in the brains of these small animals, we modified the Sakurada technique to measure regional cerebral blood flow using carbon-14 autoradiography. Seven-day-old rats underwent right common carotid artery ligation following which they were rendered hypoxic with 8% O2 at 37 degrees C. Before and during hypoxia, the rat pups received an injection of iodo(/sup 14/C)antipyrine for determination of regional cerebral blood flow. Blood flows to individual structures of the ipsilateral cerebral hemisphere were not influenced by arterial occlusion alone; flows to the contralateral hemisphere and to the brainstem and cerebellum actually increased by 25-50%. Hypoxia-ischemia was associated with decreases in regional cerebral blood flow of the ipsilateral hemisphere such that by 2 hours, flows to subcortical white matter, neocortex, striatum, and thalamus were 15, 17, 34, and 41% of control, respectively. The hierarchy of the blood flow reductions correlated closely with the distribution and extent of ischemic neuronal necrosis. However, unlike the pathologic pattern of this model, the degree of ischemia appeared homogeneous within each brain region. Blood flows to contralateral cerebral hemispheric structures were relatively unchanged from prehypoxic values, whereas flows to the brainstem and cerebellum nearly doubled and tripled, respectively. Thus, ischemia is the predominant factor that determines the topography of tissue injury to major regions of immature rat brain, whereas metabolic factors may influence the heterogeneous pattern of damage seen within individual structures.

  18. Pulsatile blood flow, shear force, energy dissipation and Murray's Law

    Directory of Open Access Journals (Sweden)

    Bengtsson Hans-Uno

    2006-08-01

    Full Text Available Abstract Background Murray's Law states that, when a parent blood vessel branches into daughter vessels, the cube of the radius of the parent vessel is equal to the sum of the cubes of the radii of daughter blood vessels. Murray derived this law by defining a cost function that is the sum of the energy cost of the blood in a vessel and the energy cost of pumping blood through the vessel. The cost is minimized when vessel radii are consistent with Murray's Law. This law has also been derived from the hypothesis that the shear force of moving blood on the inner walls of vessels is constant throughout the vascular system. However, this derivation, like Murray's earlier derivation, is based on the assumption of constant blood flow. Methods To determine the implications of the constant shear force hypothesis and to extend Murray's energy cost minimization to the pulsatile arterial system, a model of pulsatile flow in an elastic tube is analyzed. A new and exact solution for flow velocity, blood flow rate and shear force is derived. Results For medium and small arteries with pulsatile flow, Murray's energy minimization leads to Murray's Law. Furthermore, the hypothesis that the maximum shear force during the cycle of pulsatile flow is constant throughout the arterial system implies that Murray's Law is approximately true. The approximation is good for all but the largest vessels (aorta and its major branches of the arterial system. Conclusion A cellular mechanism that senses shear force at the inner wall of a blood vessel and triggers remodeling that increases the circumference of the wall when a shear force threshold is exceeded would result in the observed scaling of vessel radii described by Murray's Law.

  19. Fast blood flow visualization of high-resolution laser speckle imaging data using graphics processing unit.

    Science.gov (United States)

    Liu, Shusen; Li, Pengcheng; Luo, Qingming

    2008-09-15

    Laser speckle contrast analysis (LASCA) is a non-invasive, full-field optical technique that produces two-dimensional map of blood flow in biological tissue by analyzing speckle images captured by CCD camera. Due to the heavy computation required for speckle contrast analysis, video frame rate visualization of blood flow which is essentially important for medical usage is hardly achieved for the high-resolution image data by using the CPU (Central Processing Unit) of an ordinary PC (Personal Computer). In this paper, we introduced GPU (Graphics Processing Unit) into our data processing framework of laser speckle contrast imaging to achieve fast and high-resolution blood flow visualization on PCs by exploiting the high floating-point processing power of commodity graphics hardware. By using GPU, a 12-60 fold performance enhancement is obtained in comparison to the optimized CPU implementations.

  20. Nonlinear interactions in renal blood flow regulation

    DEFF Research Database (Denmark)

    Marsh, Donald J.; Sosnovtseva, Olga; Chon, Ki H.;

    2005-01-01

    We have developed a model of tubuloglomerular feedback (TGF) and the myogenic mechanism in afferent arterioles to understand how the two mechanisms are coupled. This paper presents the model. The tubular model predicts pressure, flow, and NaCl concentration as functions of time and tubular length...

  1. In-vivo imaging of blood flow in human retinal vessels using color Doppler optical coherence tomography

    Science.gov (United States)

    Yazdanfar, Siavash; Rollins, Andrew M.; Izatt, Joseph A.

    1999-04-01

    Quantification of retinal blood flow may lead to a better understanding of the progression and treatment of several ocular disorders, including diabetic retinopathy, age- related macular degeneration, and glaucoma. Current techniques, such as fluorescein angiography and laser Doppler velocimetry are limited, failing to provide sufficient information to the clinician. Color Doppler optical coherence tomography (CDOCT) is a novel technique using coherent heterodyne detection for simultaneous cross- sectional imaging of tissue microstructure and blood flow. This technique is capable of high spatial and velocity resolution imaging in highly scattering media. We implemented CDOCT for retinal blood flow mapping in human subjects. No dilation of the pupil was necessary. CDOCT is demonstrated for determining bidirectional flow in sub- 100micrometers diameter vessels in the retina. Additionally, we calculated Doppler broadening using the variance of depth- resolved spectra to identify regions with large velocity gradients within the Xenopus heart. This technique may be useful in quantifying local tissue perfusion in highly vascular retinal tissue.

  2. Impact of extracorporeal blood flow rate on blood pressure, pulse rate and cardiac output during haemodialysis

    DEFF Research Database (Denmark)

    Schytz, Philip Andreas; Mace, Maria Lerche; Soja, Anne Merete Boas;

    2015-01-01

    BACKGROUND: If blood pressure (BP) falls during haemodialysis (HD) [intradialytic hypotension (IDH)] a common clinical practice is to reduce the extracorporeal blood flow rate (EBFR). Consequently the efficacy of the HD (Kt/V) is reduced. However, only very limited knowledge on the effect of redu...

  3. Peripheral blood flow control in diabetes mellitus

    DEFF Research Database (Denmark)

    Hilsted, Jannik

    1991-01-01

    Long term diabetes has a profound effect on the peripheral circulation. This has been demonstrated to be due to the presence of angiopathy and autonomic neuropathy, affecting autoregulation and distensibility of the vessels as well as local and central reflex regulation of the vascular resistance....... Whereas the hemodynamic consequences of vascular denervation are well known (causing blood pressure maladaptation to a number of stimuli such as standing, exercise and agonist infusion) (Hilsted 1985), the consequences of disturbances in autoregulation and distensibility remain to be established....

  4. Development of miniaturized mass flow meter for an axial flow blood pump.

    Science.gov (United States)

    Kosaka, Ryo; Maruyama, Osamu; Nishida, Masahiro; Yamane, Takashi

    2007-05-01

    To grasp the conditions of patients and implantable artificial hearts, it is essential to monitor the blood flow rate continuously and noninvasively. However, it is difficult to monitor the pump flow rate in an implantable artificial heart, because the conventional flow meter is too large to implant into the human body, and the flow estimation method is influenced by changes in the blood characteristics and the pump performance. In particular, the power consumption has neither linearity nor uniqueness with respect to the pump flow rate in an axial flow blood pump. In this research, we develop a prototype miniaturized mass flow meter that uses centrifugal force F(c) for discharged patients with an axial flow blood pump. This flow meter measures the F(c) corresponding to the mass flow rate, and implements compensation for static pressure. Because the strain gauges are attached outside of the curved tube, this mass flow meter has no blood contact point, resulting in a compact design. To evaluate the measurement accuracy and the tracking performance, the mass flow meter was compared with the conventional ultrasonic flow meter in a mock-up circulation study. As a result, the measurement error ranging from 0.5 to 5.0 L/min was less than +/-10% with respect to the maximum flow rate. The tracking performance of pulsation flow was approximately equivalent to that of the conventional flow meter. These experiments demonstrated that the prototype miniaturized mass flow meter using F(c) could accurately measure the mass flow rate continuously and noninvasively. PMID:17470214

  5. Circulating Blood Monocyte Subclasses and Lipid-Laden Adipose Tissue Macrophages in Human Obesity.

    Directory of Open Access Journals (Sweden)

    Tal Pecht

    Full Text Available Visceral adipose tissue foam cells are increased in human obesity, and were implicated in adipose dysfunction and increased cardio-metabolic risk. In the circulation, non-classical monocytes (NCM are elevated in obesity and associate with atherosclerosis and type 2 diabetes. We hypothesized that circulating NCM correlate and/or are functionally linked to visceral adipose tissue foam cells in obesity, potentially providing an approach to estimate visceral adipose tissue status in the non-surgical obese patient.We preformed ex-vivo functional studies utilizing sorted monocyte subclasses from healthy donors. Moreover, we assessed circulating blood monocyte subclasses and visceral fat adipose tissue macrophage (ATM lipid content by flow-cytometry in paired blood and omental-fat samples collected from patients (n = 65 undergoing elective abdominal surgery.Ex-vivo, NCM and NCM-derived macrophages exhibited lower lipid accumulation capacity compared to classical or intermediate monocytes/-derived macrophages. Moreover, of the three subclasses, NCM exhibited the lowest migration towards adipose tissue conditioned-media. In a cohort of n = 65, increased %NCM associated with higher BMI (r = 0.250,p<0.05 and ATM lipid content (r = 0.303,p<0.05. Among patients with BMI≥25Kg/m2, linear regression models adjusted for age, sex or BMI revealed that NCM independently associate with ATM lipid content, particularly in men.Collectively, although circulating blood NCM are unlikely direct functional precursor cells for adipose tissue foam cells, their increased percentage in the circulation may clinically reflect higher lipid content in visceral ATMs.

  6. MRI macromolecular contrast agents as indicators of changed tumor blood flow

    International Nuclear Information System (INIS)

    Background. A rapid mapping technique derived from dynamic contrast enhanced MRI data was used to identify and characterize reduction of blood flow in fibrosarcoma SA-1 tumors treated either by application of electric pulses or vinblastine. Materials and methods. Tissue permeability surface area product (PS) and fractional blood volume (BV) were calculated on a pixel-by-pixel basis using dynamic MRI intensity data after administration of gadomer- 17 or polylysine-Gd-DTPA; prototypic macromolecular contrast agents designed for blood pool enhancement. PS and BV values of untreated tumors were compared to those of tumors treated by local application of 8 electric pulses (amplitude/distance ratio, 1300 V/cm; duration, 100 μs, frequency, 1 Hz) percutaneously to the tumor or by systemic administration of vinblastine (2.5 mg/kg). Results. Both treatments transiently, but significantly reduced tumor blood flow, application of electric pulses to the tumors being by 40% more effective in reducing tumor blood flow than systemic administration of vinblastine. PS and BV values derived with polylysine-Gd-DTPA-enhanced MRI were lower compared to those with gadomer-17, due to larger molecular size. Interestingly, Gd-DTPA-enhanced MRI did not show any significant changes of PS and BV between untreated and treated tumors. Conclusion. This study demonstrates that dynamic contrast enhanced MRI can be effectively used to qualitatively monitor tumor blood flow, and quantitatively by means of BV and PS. (author)

  7. Hall effect in electrolyte flow measurements: introduction to blood flow measurements.

    Science.gov (United States)

    Szwast, Maciej; Piatkiewicz, Wojciech

    2012-06-01

    The Hall effect has been applied to electrolyte flow measurement. It has been proven that Hall voltage does not depend on electrolyte concentration; however, there is a linear relationship between Hall voltage and flow velocity. Obtained results for electrolyte allow us to suppose that Hall effect can be used to determine blood flow. Research on blood will be conducted as the next step. PMID:22145845

  8. Design and Simulation of Axial Flow Maglev Blood Pump

    Directory of Open Access Journals (Sweden)

    Huachun Wu

    2011-03-01

    Full Text Available The axial flow maglev blood pump (AFMBP has become a global research focus and emphasis for artificial ventricular assist device, which has no mechanical contact, mechanical friction, compact structure and light weight, can effectively solve thrombus and hemolysis. Magnetic suspension and impeller is two of the important parts in the axial flow maglev blood pump, and their structure largely determines the blood pump performance. The research adopts electromagnetic and fluid finite element analysis, and puts forward a method to design the magnetic suspension and impeller of axial flow blood pump, which tacks into account the small volume of axial blood pump. The magnetic bearing’s characteristics are evaluated by electromagnetic finite element analysis. The Blades have been designed by calculating aerofoil bone line, and make simulation analysis for different thicken ways of blade by Fluent software, and make a conclusion that the blade thickened with certain rules has better characteristics in the same conditions. The results will provide some guidance for design of axial flow maglev blood pump, and establish theoretical basis for application of the implantable artificial heart pump.

  9. Single image correlation for blood flow mapping in complex vessel networks

    Science.gov (United States)

    Chirico, Giuseppe; Sironi, Laura; Bouzin, Margaux; D'Alfonso, Laura; Collini, Maddalena; Ceffa, Nicolo'G.; Marquezin, Cassia

    2015-05-01

    Microcirculation plays a key role in the maintenance and hemodynamics of tissues and organs also due to its extensive interaction with the immune system. A critical limitation of state-of-the-art clinical techniques to characterize the blood flow is their lack of the spatial resolution required to scale down to individual capillaries. On the other hand the study of the blood flow through auto- or cross-correlation methods fail to correlate the flow speed values with the morphological details required to describe an intricate network of capillaries. Here we propose to use a newly developed technique (FLICS, FLow Image Correlation Spectroscopy) that, by employing a single raster-scanned xy-image acquired in vivo by confocal or multi-photon excitation fluorescence microscopy, allows the quantitative measurement of the blood flow velocity in the whole vessel pattern within the field of view, while simultaneously maintaining the morphological information on the immobile structures of the explored circulatory system. Fluorescent flowing objects produce diagonal lines in the raster-scanned image superimposed to static morphological details. The flow velocity is obtained by computing the Cross Correlation Function (CCF) of the intensity fluctuations detected in pairs of columns of the image. The whole analytical dependence of the CCFs on the flow speed amplitude and the flow direction has been reported recently. We report here the derivation of approximated analytical relations that allows to use the CCF peak lag time and the corresponding CCF value, to directly estimate the flow speed amplitude and the flow direction. The validation has been performed on Zebrafish embryos for which the flow direction was changed systematically by rotating the embryos on the microscope stage. The results indicate that also from the CCF peak lag time it is possible to recover the flow speed amplitude within 13% of uncertainty (overestimation) in a wide range of angles between the flow and

  10. Epidural blood flow and regression of sensory analgesia during continuous postoperative epidural infusion of bupivacaine

    DEFF Research Database (Denmark)

    Mogensen, T; Højgaard, L; Scott, N B;

    1988-01-01

    Epidural blood flow was measured in seven patients undergoing elective abdominal surgery during combined lumbar epidural and general anesthesia. After an initial dose of 20 ml plain bupivacaine 0.5%, a continuous epidural infusion of bupivacaine 0.5% (8 ml/hr) was given for 16 hours for postopera......Epidural blood flow was measured in seven patients undergoing elective abdominal surgery during combined lumbar epidural and general anesthesia. After an initial dose of 20 ml plain bupivacaine 0.5%, a continuous epidural infusion of bupivacaine 0.5% (8 ml/hr) was given for 16 hours...... surgery, and 8, 12, and 16 hours later during the continuous infusion. Initial blood flow was 6.0 +/- 0.7 ml/min per 100 g tissue (mean +/- SEM). After epidural bupivacaine, blood flow increased in all seven patients to 7.4 +/- 0.7 ml (P less than 0.02). Initial level of sensory analgesia was T4.5 +/- 0...... than 0.03) in the other five patients as the level of sensory analgesia regressed postoperatively. These data suggest that changes in epidural blood flow during continuous epidural infusion of bupivacaine, and thus changes in rates of vascular absorption of bupivacaine from the epidural space, may...

  11. Effects of Aortic Irregularities on the Blood Flow

    Science.gov (United States)

    Gutmark-Little, Iris; Prahl-Wittberg, Lisa; van Wyk, Stevin; Mihaescu, Mihai; Fuchs, Laszlo; Backeljauw, Philippe; Gutmark, Ephraim

    2013-11-01

    Cardiovascular defects characterized by geometrical anomalies of the aorta and its effect on the blood flow are investigated. The flow characteristics change with the aorta geometry and the rheological properties of the blood. Flow characteristics such as wall shear stress often play an important role in the development of vascular disease. In the present study, blood is considered to be non-Newtonian and is modeled using the Quemada model, an empirical model that is valid for different red blood cell loading. Three patient-specific aortic geometries are studied using Large Eddy Simulations (LES). The three geometries represent malformations that are typical in patients populations having a genetic disorder called Turner syndrome. The results show a highly complex flow with regions of recirculation that are enhanced in two of the three aortas. Moreover, blood flow is diverted, due to the malformations, from the descending aorta to the three side branches of the arch. The geometry having an elongated transverse aorta has larger areas of strong oscillatory wall shear stress.

  12. Nocturnal foot blood flow in patients with arterial insufficiency

    DEFF Research Database (Denmark)

    Jelnes, Rolf; Tønnesen, K H

    1984-01-01

    Twenty-four hour continuous recording of xenon (133Xe) wash-out from the forefoot was performed on patients with normal circulations (n = 10) and on patients with different degrees of arterial insufficiency (n = 36). During day hours the calculated subcutaneous blood flow in the forefoot was on a...... claudication. In patients with severe ischaemia, i.e. having rest pain, the blood flow decreased by approximately 50%. The changes in local blood flow may be due to changes in local sympathetic tone and to changes in local perfusion pressure.......Twenty-four hour continuous recording of xenon (133Xe) wash-out from the forefoot was performed on patients with normal circulations (n = 10) and on patients with different degrees of arterial insufficiency (n = 36). During day hours the calculated subcutaneous blood flow in the forefoot...... was on average the same in patients with normal circulations and in patients with different degrees of arterial insufficiency (mean: 2.0 +/- 0.8 ml min-1 100 g-1). During sleep the blood flow nearly doubled in patients with normal circulations; no systematic change was seen in patients with intermittent...

  13. An analysis of the sluicing gate in pulmonary blood flow.

    Science.gov (United States)

    Fung, Y C; Zhuang, F Y

    1986-05-01

    For pulmonary blood flow in zone 2 condition, in which the blood pressure in the venule (pven) is lower than the alveolar gas pressure (pA), the blood exiting from the capillary sheet and entering a venule must go through a sluicing gate. The sluicing gate exists because the venule remains patent while the capillaries will collapse when the static pressure of blood falls below the alveolar gas pressure. In the original theory of sheet flow the effect of the tension in the interalveolar septa on the flow through the sluicing gate was ignored. Since the tension multiplied by the curvature of the membrane is equivalent to a lateral pressure tending to open the gate, and since the curvature of the capillary wall is high in the gate region, this effect may be important. The present analysis improves the original theory and demonstrates that the effect of membrane tension is to cause flow to increase when the venous pressure continues to decrease. The shape of the sluicing gate resembles that of a venturi tube, and can be determined by an iterative integration of the differential equations. The result forms an important link in the theory of pulmonary blood flow in zone 2 condition.

  14. Sodium hydrosulfide alleviates pulmonary artery collagen remodeling in rats with high pulmonary blood flow.

    Science.gov (United States)

    Li, Xiaohui; Du, Junbao; Jin, Hongfang; Geng, Bin; Tang, Chaoshu

    2008-11-01

    This study aimed to explore the effect of sodium hydrosulfide (NaHS) on pulmonary artery collagen remodeling in rats with high pulmonary blood flow. Thirty-two Sprague-Dawley rats were randomly divided into a sham group, shunt group, sham + NaHS (an H2S donor) group, and shunt + NaHS group. After 11 weeks of shunting, mean pulmonary artery pressure (MPAP), relative median area (RMA) of pulmonary arteries, H2S concentration in lung tissues, plasma endothelin-1 (ET-1) levels, and ET-1 mRNA in lung tissues were investigated. Collagen I and collagen III were evaluated by immunohistochemistry. Hydroxyproline assay and Sirius-red staining were performed. Matrix metalloproteinase-13 (MMP-13), tissue inhibitor of metalloproteinase-1 (TIMP-1), and connective tissue growth factor (CTGF) were evaluated by immunohistochemistry. After 11 weeks of shunting, rats showed a significant pulmonary hypertension and pulmonary artery collagen remodeling in association with a decrease in lung tissue H2S content. After NaHS treatment for 11 weeks, lung tissue H(2)S content was increased, whereas MPAP was attenuated and RMA was reduced. Meanwhile, pulmonary artery collagen I and collagen III protein expressions of intra-acinar pulmonary arteries were inhibited, but MMP-13/TIMP-1 ratio was augmented with a decreased plasma ET-1 content and lung tissue ET-1mRNA and CTGF expressions. The downregulation of H(2)S is involved in the development of pulmonary artery collagen remodeling induced by high pulmonary blood flow.

  15. Combined inhibition of nitric oxide and prostaglandins reduces human skeletal muscle blood flow during exercise

    Science.gov (United States)

    Boushel, Robert; Langberg, Henning; Gemmer, Carsten; Olesen, Jens; Crameri, Regina; Scheede, Celena; Sander, Michael; Kjær, Michael

    2002-01-01

    The vascular endothelium is an important mediator of tissue vasodilatation, yet the role of the specific substances, nitric oxide (NO) and prostaglandins (PG), in mediating the large increases in muscle perfusion during exercise in humans is unclear. Quadriceps microvascular blood flow was quantified by near infrared spectroscopy and indocyanine green in six healthy humans during dynamic knee extension exercise with and without combined pharmacological inhibition of NO synthase (NOS) and PG by l-NAME and indomethacin, respectively. Microdialysis was applied to determine interstitial release of PG. Compared to control, combined blockade resulted in a 5- to 10-fold lower muscle interstitial PG level. During control incremental knee extension exercise, mean blood flow in the quadriceps muscles rose from 10 ± 0.8 ml (100 ml tissue)−1 min−1 at rest to 124 ± 19, 245 ± 24, 329 ± 24 and 312 ± 25 ml (100 ml tissue)−1 min−1 at 15, 30, 45 and 60 W, respectively. During inhibition of NOS and PG, blood flow was reduced to 8 ± 0.5 ml (100 ml tissue)−1 min−1 at rest, and 100 ± 13, 163 ± 21, 217 ± 23 and 256 ± 28 ml (100 ml tissue)−1 min−1 at 15, 30, 45 and 60 W, respectively (P < 0.05 vs. control). In conclusion, combined inhibition of NOS and PG reduced muscle blood flow during dynamic exercise in humans. These findings demonstrate an important synergistic role of NO and PG for skeletal muscle vasodilatation and hyperaemia during muscular contraction. PMID:12205200

  16. Quantitative myocardial blood flow with Rubidium-82 PET

    DEFF Research Database (Denmark)

    Hagemann, Christoffer E; Ghotbi, Adam A; Kjær, Andreas;

    2015-01-01

    Positron emission tomography (PET) allows assessment of myocardial blood flow in absolute terms (ml/min/g). Quantification of myocardial blood flow (MBF) and myocardial flow reserve (MFR) extend the scope of conventional semi-quantitative myocardial perfusion imaging (MPI): e.g. in 1) identificat......Positron emission tomography (PET) allows assessment of myocardial blood flow in absolute terms (ml/min/g). Quantification of myocardial blood flow (MBF) and myocardial flow reserve (MFR) extend the scope of conventional semi-quantitative myocardial perfusion imaging (MPI): e.g. in 1...... pretest probability of CAD can support the clinical decision-making in treatment of CAD patients as a complementary tool to the invasive coronary angiography (CAG). Recently, several studies have proven Rubidium-82 ((82)Rb) PET's long-term prognostic value by a significant association between compromised...... global MFR and major adverse cardiovascular events (MACE), and together with new diagnostic possibilities from measuring the longitudinal myocardial perfusion gradient, cardiac (82)Rb PET faces a promising clinical future. This article reviews current evidence on quantitative (82)Rb PET's ability...

  17. Inner ocular blood flow responses to an acute decrease in blood pressure in resting humans

    International Nuclear Information System (INIS)

    Whether inner ocular vessels have an autoregulatory response to acute fluctuations in blood pressure is unclear. We tried to examine the validity of acute hypotension elicited by thigh-cuff release as to assess the dynamic autoregulation in the ocular circulation. Blood flow velocity in the superior nasal and inferior temporal retinal arterioles, and in the retinal and choroidal vasculature were measured with the aid of laser speckle flowgraphy before and immediately after an acute decrease in blood pressure in 20 healthy subjects. Acute hypotension was induced by a rapid release of bilateral thigh occlusion cuffs that had been inflated to 220 mmHg for 2 min. The ratio of the relative change in retinal and choroidal blood flow velocity to the relative change in mean arterial blood pressure (MAP) was calculated. Immediately after cuff release, the MAP and blood flows in the all ocular target vessels decreased significantly from the baseline values obtained before thigh-cuff release. The ratio of the relative change in inner ocular blood flow velocity to that in the MAP exceeded 1% / %mmHg. An explicit dynamic autoregulation in inner ocular vessels cannot be demonstrated in response to an acute hypotension induced by the thigh-cuff release technique. (paper)

  18. Implantable sensor for intraoperative and postoperative monitoring of blood flow: a preliminary report.

    Science.gov (United States)

    Rabinovitz, R S; Hartley, C J; Michael, L H; Entman, M L; Hawkins, H K; Sekela, M E; Noon, G P

    1990-08-01

    We have developed an implantable 20 MHz Doppler flow sensor, to monitor blood flow in patients after operation. During surgery the sensor is wrapped around a blood vessel and secured in place with a releasable tie. No tissue puncturing techniques are required. The lead wires, together with a release cable, are exteriorized through the chest wall. Several days after operation, the tie is externally released, and the sensor is pulled out. Twenty-seven sensors were implanted in 24 dogs for up to 16 days. All were extracted successfully with minimal visible behavioral reaction in the awake dogs and caused no thrombosis or vascular damage. The Doppler velocity signals had excellent linear correlations (r = 0.99) with data from electromagnetic flow sensors and timed blood collections. In addition, the sensors were applied to coronary artery bypass grafts in 31 patients for up to 2 days after operation. High-quality signals were obtained, and intraoperatively recorded signals agreed well with simultaneous electromagnetic flow tracings. All sensors were extracted with minimal discomfort to the awake patients and with no complications. Thus, the implantable flow sensor is a safe, reliable, accurate, and simple method for intraoperative and postoperative monitoring of blood flow in vessels 2.5 to 5 mm in diameter. PMID:2199684

  19. The endothelial glycocalyx promotes homogenous blood flow distribution within the microvasculature.

    Science.gov (United States)

    McClatchey, P Mason; Schafer, Michal; Hunter, Kendall S; Reusch, Jane E B

    2016-07-01

    Many common diseases involve impaired tissue perfusion, and heterogeneous distribution of blood flow in the microvasculature contributes to this pathology. The physiological mechanisms regulating homogeneity/heterogeneity of microvascular perfusion are presently unknown. Using established empirical formulations for blood viscosity modeling in vivo (blood vessels) and in vitro (glass tubes), we showed that the in vivo formulation predicts more homogenous perfusion of microvascular networks at the arteriolar and capillary levels. Next, we showed that the more homogeneous blood flow under simulated in vivo conditions can be explained by changes in red blood cell interactions with the vessel wall. Finally, we demonstrated that the presence of a space-filling, semipermeable layer (such as the endothelial glycocalyx) at the vessel wall can account for the changes of red blood cell interactions with the vessel wall that promote homogenous microvascular perfusion. Collectively, our results indicate that the mechanical properties of the endothelial glycocalyx promote homogeneous microvascular perfusion. Preservation or restoration of normal glycocalyx properties may be a viable strategy for improving tissue perfusion in a variety of diseases.

  20. The endothelial glycocalyx promotes homogenous blood flow distribution within the microvasculature.

    Science.gov (United States)

    McClatchey, P Mason; Schafer, Michal; Hunter, Kendall S; Reusch, Jane E B

    2016-07-01

    Many common diseases involve impaired tissue perfusion, and heterogeneous distribution of blood flow in the microvasculature contributes to this pathology. The physiological mechanisms regulating homogeneity/heterogeneity of microvascular perfusion are presently unknown. Using established empirical formulations for blood viscosity modeling in vivo (blood vessels) and in vitro (glass tubes), we showed that the in vivo formulation predicts more homogenous perfusion of microvascular networks at the arteriolar and capillary levels. Next, we showed that the more homogeneous blood flow under simulated in vivo conditions can be explained by changes in red blood cell interactions with the vessel wall. Finally, we demonstrated that the presence of a space-filling, semipermeable layer (such as the endothelial glycocalyx) at the vessel wall can account for the changes of red blood cell interactions with the vessel wall that promote homogenous microvascular perfusion. Collectively, our results indicate that the mechanical properties of the endothelial glycocalyx promote homogeneous microvascular perfusion. Preservation or restoration of normal glycocalyx properties may be a viable strategy for improving tissue perfusion in a variety of diseases. PMID:27199117

  1. Verapamil buffering effect on the abrupt elevation in blood pressure, linkage with microcirculatory blood flow.

    Science.gov (United States)

    Gmitrov, J

    2008-01-01

    1 We studied the effects of verapamil on sudden elevation in blood pressure, microcirculation and arterial baroreflex sensitivity (BRS). 2 Thirty experiments (10 controls and 20 with verapamil) were performed in rabbits sedated using pentobarbital infusion (5 mg kg(-1) h(-1)). 3 BRS, mean femoral artery blood pressure (MAP), heart rate (HR) and ear lobe skin microcirculatory blood flow, estimated using microphotoelectric plethysmography (MPPG), were simultaneously measured during 30 min of verapamil infusion (20 mug kg(-1) min(-1)). BRS was assessed from HR and MAP responses to intravenous phenylephrine (Ph) and by power spectral analysis using transfer function (TF) from MAP to the HR (BRS(Ph,TF)). 4 Verapamil significantly increased microcirculatory blood flow, and decreased BRS(Ph,TF) and phenylephrine-induced abrupt elevation in MAP (MAP(AE)). 5 A significant inverse correlation was found between verapamil-induced changes in MAP(AE), BRS and in microcirculatory blood flow, measured before phenylephrine blood pressure ramps (DeltaMAP(AE) with DeltaBRS(TF), r = -0.47, P < 0.036; DeltaMAP(AE) with DeltaMPPG, r = -0.49, P < 0.025). 6 These results suggest involvement of the arterial baroreflex and vascular blood pressure-buffering mechanisms, their enhancement by verapamil, and thus a potential benefit of verapamil in cardiovascular conditions where patients present with abrupt high elevations in blood pressure. PMID:18598288

  2. Blood flow mechanics and oxygen transport and delivery in the retinal microcirculation: multiscale mathematical modeling and numerical simulation.

    Science.gov (United States)

    Causin, Paola; Guidoboni, Giovanna; Malgaroli, Francesca; Sacco, Riccardo; Harris, Alon

    2016-06-01

    The scientific community continues to accrue evidence that blood flow alterations and ischemic conditions in the retina play an important role in the pathogenesis of ocular diseases. Many factors influence retinal hemodynamics and tissue oxygenation, including blood pressure, blood rheology, oxygen arterial permeability and tissue metabolic demand. Since the influence of these factors on the retinal circulation is difficult to isolate in vivo, we propose here a novel mathematical and computational model describing the coupling between blood flow mechanics and oxygen ([Formula: see text]) transport in the retina. Albeit in a simplified manner, the model accounts for the three-dimensional anatomical structure of the retina, consisting in a layered tissue nourished by an arteriolar/venular network laying on the surface proximal to the vitreous. Capillary plexi, originating from terminal arterioles and converging into smaller venules, are embedded in two distinct tissue layers. Arteriolar and venular networks are represented by fractal trees, whereas capillary plexi are represented using a simplified lumped description. In the model, [Formula: see text] is transported along the vasculature and delivered to the tissue at a rate that depends on the metabolic demand of the various tissue layers. First, the model is validated against available experimental results to identify baseline conditions. Then, a sensitivity analysis is performed to quantify the influence of blood pressure, blood rheology, oxygen arterial permeability and tissue oxygen demand on the [Formula: see text] distribution within the blood vessels and in the tissue. This analysis shows that: (1) systemic arterial blood pressure has a strong influence on the [Formula: see text] profiles in both blood and tissue; (2) plasma viscosity and metabolic consumption rates have a strong influence on the [Formula: see text] tension at the level of the retinal ganglion cells; and (3) arterial [Formula: see text

  3. A numerical study of blood flow using mixture theory.

    Science.gov (United States)

    Wu, Wei-Tao; Aubry, Nadine; Massoudi, Mehrdad; Kim, Jeongho; Antaki, James F

    2014-03-01

    In this paper, we consider the two dimensional flow of blood in a rectangular microfluidic channel. We use Mixture Theory to treat this problem as a two-component system: One component is the red blood cells (RBCs) modeled as a generalized Reiner-Rivlin type fluid, which considers the effects of volume fraction (hematocrit) and influence of shear rate upon viscosity. The other component, plasma, is assumed to behave as a linear viscous fluid. A CFD solver based on OpenFOAM(®) was developed and employed to simulate a specific problem, namely blood flow in a two dimensional micro-channel, is studied. Finally to better understand this two-component flow system and the effects of the different parameters, the equations are made dimensionless and a parametric study is performed. PMID:24791016

  4. Mediators of increased blood flow in porcine skin

    Directory of Open Access Journals (Sweden)

    H. D. Moore

    1992-01-01

    Full Text Available Nicotinates and benzalkonium chloride (B.Cl cause inflammatory changes in human skin, thought to be dependent upon prostaglandin formation. This study has examined the effects of hexyl-nicotinate (HN and B.Cl on blood flow in porcine skin. The role of prostaglandins and interleukin (IL-1 in the blood flow response has been investigated. Blood flow was increased by both HN and B.Cl, the response to B.Cl being more protracted. Cyclooxygenase inhibitor pretreatment reduced these responses. IL-1-like biological activity was identified in normal porcine epidermis and the amounts recovered from inflamed skin were similar. Thus prostaglandin formation in HN or B.Cl-induced inflammation, if IL-1 dependent, is not associated with the loss of significant amounts of the cytokine from the epidermis.

  5. Heart blood flow simulation: a perspective review.

    Science.gov (United States)

    Doost, Siamak N; Ghista, Dhanjoo; Su, Boyang; Zhong, Liang; Morsi, Yosry S

    2016-01-01

    Cardiovascular disease (CVD), the leading cause of death today, incorporates a wide range of cardiovascular system malfunctions that affect heart functionality. It is believed that the hemodynamic loads exerted on the cardiovascular system, the left ventricle (LV) in particular, are the leading cause of CVD initiation and propagation. Moreover, it is believed that the diagnosis and prognosis of CVD at an early stage could reduce its high mortality and morbidity rate. Therefore, a set of robust clinical cardiovascular assessment tools has been introduced to compute the cardiovascular hemodynamics in order to provide useful insights to physicians to recognize indicators leading to CVD and also to aid the diagnosis of CVD. Recently, a combination of computational fluid dynamics (CFD) and different medical imaging tools, image-based CFD (IB-CFD), has been widely employed for cardiovascular functional assessment by providing reliable hemodynamic parameters. Even though the capability of CFD to provide reliable flow dynamics in general fluid mechanics problems has been widely demonstrated for many years, up to now, the clinical implications of the IB-CFD patient-specific LVs have not been applicable due to its limitations and complications. In this paper, we review investigations conducted to numerically simulate patient-specific human LV over the past 15 years using IB-CFD methods. Firstly, we divide different studies according to the different LV types (physiological and different pathological conditions) that have been chosen to reconstruct the geometry, and then discuss their contributions, methodologies, limitations, and findings. In this regard, we have studied CFD simulations of intraventricular flows and related cardiology insights, for (i) Physiological patient-specific LV models, (ii) Pathological heart patient-specific models, including myocardial infarction, dilated cardiomyopathy, hypertrophic cardiomyopathy and hypoplastic left heart syndrome. Finally, we

  6. Effect of pregnancy on regional cerebral blood flow

    International Nuclear Information System (INIS)

    Regional cerebral blood flow (r-CBF) of 10 pregnant women were quantified by 133Xe SPECT study with inhalation method before and after artificial abortion. During pregnancy, value of r-CBF in each region except occipital lobe was significantly higher than that of the post abortion. Arterial blood gas was analyzed after SPECT procedure. Pco2 concentration increased significantly after artificial abortion. Although its mechanism is unknown, our preliminary work demonstrates that r-CBF increased by pregnancy. (author)

  7. Cerebral blood flow velocity changes after rapid administration of surfactant.

    OpenAIRE

    Cowan, F.; Whitelaw, A; D. Wertheim; Silverman, M

    1991-01-01

    A computer linked Doppler system was used to make continuous measurements of cerebral blood flow velocity (CBFV) from the middle cerebral artery, mean arterial blood pressure (MAP) from the umbilical artery, and heart rate before, during, and for 20 minutes after the endotracheal administration of 200 mg/kg of porcine surfactant in 10 preterm infants with respiratory distress syndrome. Within two minutes of surfactant administration, there was a median fall of 6 mm Hg (15%) fall in MAP and 36...

  8. Fontan Outcomes and Pulmonary Blood Flow at Birth.

    Science.gov (United States)

    Evans, William N; Acherman, Ruben J; Reardon, Leigh C; Ciccolo, Michael L; Galindo, Alvaro; Rothman, Abraham; Winn, Brody J; Yumiaco, Noel S; Restrepo, Humberto

    2016-01-01

    We previously noted, in a small group of post-Fontan patients, a possible association between hepatic fibrosis scores and the status of pulmonary blood flow at birth. To further explore this observation, we examined data from all Fontan patients seen in our center from July 2010 to March 2015. We identified 200 patients for analysis. Of the 200 patients, 56 underwent transvenous-hepatic biopsy. Of the 200 patients, 13 (6.5%) had protein-losing enteropathy. We divided both the 56 biopsy patients and the entire cohort of 200 patients into 4 groups: (1) unobstructed pulmonary blood flow at birth with functional left ventricles, (2) unobstructed pulmonary blood flow at birth with functional right ventricles, (3) obstructed pulmonary blood flow at birth with functional left ventricles, and (4) obstructed pulmonary blood flow at birth with functional right ventricles. Analysis of the 56 liver-biopsy patient groups showed median hepatic total-fibrosis scores for the 4 groups of 2 (0-6), 2 (0-8), 3 (2-6), and 4 (1-8), respectively, with statistical significance between groups 4 and 1 (p = 0.031). For the entire cohort of 200 patients, we analyzed the incidence of protein-losing enteropathy for each of the four groups and found protein-losing enteropathy percent occurrences of 0, 2.9, 8.8, and 16.1, respectively, with statistical significance between groups 4 and 2 (p = 0.031) and between groups 4 and 1 (p = 0.025). A history of obstructed pulmonary blood flow at birth, coupled with a functional right ventricle, may predict a poorer long-term Fontan outcome.

  9. Cerebral blood flow in asymptomatic individuals

    International Nuclear Information System (INIS)

    We studied the relationship between cortical grey matter flow (CBF) and age, cerebrovascular risk factors and the severity of subcortical hypersignals (HS, hyperintensity score in MRI) in 47 asymptomatic subjects with cerebrovascular risk factors. Multiple regression analysis revealed that HS was most strongly related to CBF, and that hematocrit, age and evidence of ischemic change detected in the electrocardiogram also appeared to be independent determinants of CBF. Both the severity and location of hypersignals were correlated with CBF. The most significant negative correlation observed was that between CBF and HS in the basal ganglia-thalamic region, where the degree of signal abnormality was modest. Decreased CBF in asymptomatic subjects with cerebrovascular risk factors may be related to microcirculatory disturbance associated with elevated hematocrit and an increase in the number of risk factors, and functional suppression of cerebral cortex due to the neuronal disconnection associated with subcortical lesions. In addition, impaired cerebral circulation may be related to MRI signal abnormalities. (author)

  10. Pulmonary blood flow distribution in transposition of the great arteries

    International Nuclear Information System (INIS)

    Pulmonary blood flow distribution was studied by scintillation scanning of the lungs after the infusion of iodine-131-labeled macroaggregates of human albumin before and after the Mustard operation in 53 patients with transposition of the great arteries. The patients were classified as follows: Group 1 (24 infants with uncomplicated transposition of the great arteries); Group II (18 patients with transposition and ventricular septal defect); and Group III (11 patients with transposition, ventricular septal defect and pulmonary obstruction). Before operation, 21 patients had a normal distribution of pulmonary blood flow, 10 had preferential flow to the right lung and 2 had preferential flow to the left lung. After operation, 19 had a normal pattern of pulmonary blood flow, 21 had preferential flow to the right lung and 3 had preferential flow to the left lung. The scanning studies have proved helpful in follow-up of patients to rule out recurrence of the shunt, pulmonary or systemic venous obstruction, development of pulmonary hypertension and occlusion of a palliative systemic-pulmonary shunt

  11. Flow of Red Blood Cells in Stenosed Microvessels

    Science.gov (United States)

    Vahidkhah, Koohyar; Balogh, Peter; Bagchi, Prosenjit

    2016-06-01

    A computational study is presented on the flow of deformable red blood cells in stenosed microvessels. It is observed that the Fahraeus-Lindqvist effect is significantly enhanced due to the presence of a stenosis. The apparent viscosity of blood is observed to increase by several folds when compared to non-stenosed vessels. An asymmetric distribution of the red blood cells, caused by geometric focusing in stenosed vessels, is observed to play a major role in the enhancement. The asymmetry in cell distribution also results in an asymmetry in average velocity and wall shear stress along the length of the stenosis. The discrete motion of the cells causes large time-dependent fluctuations in flow properties. The root-mean-square of flow rate fluctuations could be an order of magnitude higher than that in non-stenosed vessels. Several folds increase in Eulerian velocity fluctuation is also observed in the vicinity of the stenosis. Surprisingly, a transient flow reversal is observed upstream a stenosis but not downstream. The asymmetry and fluctuations in flow quantities and the flow reversal would not occur in absence of the cells. It is concluded that the flow physics and its physiological consequences are significantly different in micro- versus macrovascular stenosis.

  12. Metabolic control of muscle blood flow during exercise in humans

    DEFF Research Database (Denmark)

    Boushel, Robert Christopher

    2003-01-01

    and the vasculature that induce vasodilation. A link between muscle metabolic events and microvascular control of blood flow is illustrated by local dilation of terminal arterioles during contraction of muscle fibers and conduction of vasodilation upstream. Endothelial-derived vasodilator mechanisms are known...... to exert control of muscle vasodilation. Adenosine, nitric oxide (NO), prostacyclin (PGI2), and endothelial-derived hyperpolarization factor (EDHF) are possible mediators of muscle vasodilation during exercise. In humans, adenosine has been shown to contribute to functional hyperemia as blood flow...

  13. Instability of the middle cerebral artery blood flow in response to CO2.

    Directory of Open Access Journals (Sweden)

    Rosemary E Regan

    Full Text Available BACKGROUND: The middle cerebral artery supplies long end-artery branches to perfuse the deep white matter and shorter peripheral branches to perfuse cortical and subcortical tissues. A generalized vasodilatory stimulus such as carbon dioxide not only results in an increase in flow to these various tissue beds but also redistribution among them. We employed a fast step increase in carbon dioxide to detect the dynamics of the cerebral blood flow response. METHODOLOGY/PRINCIPAL FINDINGS: The study was approved by the Research Ethics Board of the University Health Network at the University of Toronto. We used transcranial ultrasound to measure the time course of middle cerebral artery blood flow velocity in 28 healthy adults. Normoxic, isoxic step increases in arterial carbon dioxide tension of 10 mmHg from both hypocapnic and normocapnic baselines were produced using a new prospective targeting system that enabled a more rapid step change than has been previously achievable. In most of the 28 subjects the responses at both carbon dioxide ranges were characterised by more complex responses than a single exponential rise. Most responses were characterised by a fast initial response which then declined rapidly to a nadir, followed by a slower secondary response, with some showing oscillations before stabilising. CONCLUSIONS/SIGNIFICANCE: A rapid step increase in carbon dioxide tension is capable of inducing instability in the cerebral blood flow control system. These dynamic aspects of the cerebral blood flow responses to rapid changes in carbon dioxide must be taken into account when using transcranial blood flow velocity in a single artery segment to measure cerebrovascular reactivity.

  14. Accurate blood flow measurements: are artificial tracers necessary?

    Directory of Open Access Journals (Sweden)

    Christian Poelma

    Full Text Available Imaging-based blood flow measurement techniques, such as particle image velocimetry, have become an important tool in cardiovascular research. They provide quantitative information about blood flow, which benefits applications ranging from developmental biology to tumor perfusion studies. Studies using these methods can be classified based on whether they use artificial tracers or red blood cells to visualize the fluid motion. We here present the first direct comparison in vivo of both methods. For high magnification cases, the experiments using red blood cells strongly underestimate the flow (up to 50% in the present case, as compared to the tracer results. For medium magnification cases, the results from both methods are indistinguishable as they give the same underestimation of the real velocities (approximately 33%, based on in vitro reference measurements. These results suggest that flow characteristics reported in literature cannot be compared without a careful evaluation of the imaging characteristics. A method to predict the expected flow averaging behavior for a particular facility is presented.

  15. Effect of blood flow parameters on flow patterns at arterial bifurcations--studies in models.

    Science.gov (United States)

    Liepsch, D W

    1990-01-01

    Atherosclerotic lesions are found primarily at arterial bends and bifurcations. Flow disturbances at these anatomic sites play a major role in atherogenesis. How hemodynamic factors such as vessel geometry, the pulsatile nature of blood flow, vessel wall elasticity and the non-Newtonian flow behavior of blood influence the flow field at these sites must be clarified. We have performed fundamental studies using a birefringent solution in a simplified rigid 90 degree T-bifurcation and pulsatile flow. The velocity distribution was measured with a laser Doppler anemometer. Flow in an elastic abdominal aorta model has been visualized using magnetic resonance imaging. In both flow studies, zones with negative velocity were found. These model measurements demonstrate that no flow parameter can be neglected. Further detailed studies are necessary to examine the interaction between fluid dynamic and cellular surface properties. PMID:2404201

  16. Blood Pump Development Using Rocket Engine Flow Simulation Technology

    Science.gov (United States)

    Kiris, Cetin C.; Kwak, Dochan

    2002-01-01

    This viewgraph presentation provides information on the transfer of rocket engine flow simulation technology to work involving the development of blood pumps. Details are offered regarding the design and requirements of mechanical heart assist devices, or VADs (ventricular assist device). There are various computational fluid dynamics issues involved in the visualization of flow in such devices, and these are highlighted and compared to those of rocket turbopumps.

  17. Diffuse optical correlation tomography of cerebral blood flow during cortical spreading depression in rat brain

    Science.gov (United States)

    Zhou, Chao; Yu, Guoqiang; Furuya, Daisuke; Greenberg, Joel; Yodh, Arjun; Durduran, Turgut

    2006-02-01

    Diffuse optical correlation methods were adapted for three-dimensional (3D) tomography of cerebral blood flow (CBF) in small animal models. The image reconstruction was optimized using a noise model for diffuse correlation tomography which enabled better data selection and regularization. The tomographic approach was demonstrated with simulated data and during in-vivo cortical spreading depression (CSD) in rat brain. Three-dimensional images of CBF were obtained through intact skull in tissues(~4mm) deep below the cortex.

  18. Bone tissue engineering: the role of interstitial fluid flow

    Science.gov (United States)

    Hillsley, M. V.; Frangos, J. A.

    1994-01-01

    It is well established that vascularization is required for effective bone healing. This implies that blood flow and interstitial fluid (ISF) flow are required for healing and maintenance of bone. The fact that changes in bone blood flow and ISF flow are associated with changes in bone remodeling and formation support this theory. ISF flow in bone results from transcortical pressure gradients produced by vascular and hydrostatic pressure, and mechanical loading. Conditions observed to alter flow rates include increases in venous pressure in hypertension, fluid shifts occurring in bedrest and microgravity, increases in vascularization during the injury-healing response, and mechanical compression and bending of bone during exercise. These conditions also induce changes in bone remodeling. Previously, we hypothesized that interstitial fluid flow in bone, and in particular fluid shear stress, serves to mediate signal transduction in mechanical loading- and injury-induced remodeling. In addition, we proposed that a lack or decrease of ISF flow results in the bone loss observed in disuse and microgravity. The purpose of this article is to review ISF flow in bone and its role in osteogenesis.

  19. Computational Dynamics of Arterial Blood Flow in the Presence of Magnetic Field and Thermal Radiation Therapy

    Directory of Open Access Journals (Sweden)

    T. Chinyoka

    2014-01-01

    Full Text Available We conduct a numerical study to determine the influence of magnetic field and thermal radiation on both velocity and temperature distributions in a single blood vessel. The model here assumes that blood is a Newtonian incompressible conducting fluid with radially varying viscosity due to hematocrit variation. The transient equations of momentum and energy transport governing the flow in an axisymmetric configuration are solved numerically using a semi-implicit finite difference method. Results are presented graphically and discussed both qualitatively and quantitatively from the physiological point of view. The results of this work may enhance current understanding of the factors that determine the effects of hyperthermia treatment on tumor tissues.

  20. Ultrasonic Doppler blood flow meter for extracorporeal circulation

    Science.gov (United States)

    Dantas, Ricardo G.; Costa, Eduardo T.; Maia, Joaquim M.; Nantes Button, Vera L. d. S.

    2000-04-01

    In cardiac surgeries it is frequently necessary to carry out interventions in internal heart structures, and where the blood circulation and oxygenation are made by artificial ways, out of the patient's body, in a procedure known as extracorporeal circulation (EC). During this procedure, one of the most important parameters, and that demands constant monitoring, is the blood flow. In this work, an ultrasonic pulsed Doppler blood flowmeter, to be used in an extracorporeal circulation system, was developed. It was used a 2 MHz ultrasonic transducer, measuring flows from 0 to 5 liters/min, coupled externally to the EC arterial line destined to adults perfusion (diameter of 9.53 mm). The experimental results using the developed flowmeter indicated a maximum deviation of 3.5% of full scale, while the blood flow estimator based in the rotation speed of the peristaltic pump presented deviations greater than 20% of full scale. This ultrasonic flowmeter supplies the results in a continuous and trustworthy way, and it does not present the limitations found in those flowmeters based in other transduction methods. Moreover, due to the fact of not being in contact with the blood, it is not disposable and it does not need sterilization, reducing operational costs and facilitating its use.

  1. Radionuclide Tracers for Myocardial Perfusion Imaging and Blood Flow Quantification.

    Science.gov (United States)

    deKemp, Robert A; Renaud, Jennifer M; Klein, Ran; Beanlands, Rob S B

    2016-02-01

    Myocardial perfusion imaging is performed most commonly using Tc-99m-sestamibi or tetrofosmin SPECT as well as Rb-82-rubidium or N-13-ammonia PET. Diseased-to-normal tissue contrast is determined by the tracer retention fraction, which decreases nonlinearly with flow. Reduced tissue perfusion results in reduced tracer retention, but the severity of perfusion defects is typically underestimated by 20% to 40%. Compared to SPECT, retention of the PET tracers is more linearly related to flow, and therefore, the perfusion defects are measured more accurately using N-13-ammonia or Rb-82.

  2. Velocity estimation using synthetic aperture imaging [blood flow

    OpenAIRE

    Nikolov, Svetoslav; Jensen, Jørgen Arendt

    2001-01-01

    Presented an approach for synthetic aperture blood flow ultrasound imaging. Estimates with a low bias and standard deviation can be obtained with as few as eight emissions. The performance of the new estimator is verified using both simulations and measurements. The results demonstrate that a fully functioning synthetic aperture scanner can be made

  3. History of International Society for Cerebral Blood Flow and Metabolism

    DEFF Research Database (Denmark)

    Paulson, Olaf B; Kanno, Iwao; Reivich, Martin;

    2012-01-01

    dealing with CBF and metabolism were arranged, and the fast growing research led to a demand for a specialized journal. In this scientific environment, the International Society for Cerebral Blood Flow and Metabolism (ISCBFM) and its official Journal of Cerebral Metabolism were established in 1981 and has...

  4. Renal blood flow in experimental septic acute renal failure

    NARCIS (Netherlands)

    Langenberg, C.; Wan, L.; Egi, M.; May, C. N.; Bellomo, R.

    2006-01-01

    Reduced renal blood flow (RBF) is considered central to the pathogenesis of septic acute renal failure (ARF). However, no controlled experimental studies have continuously assessed RBF during the development of severe septic ARF. We conducted a sequential animal study in seven female Merino sheep. F

  5. Development of a miniature intraventricular axial flow blood pump.

    Science.gov (United States)

    Yamazaki, K; Umezu, M; Koyanagi, H; Outa, E; Ogino, S; Otake, Y; Shiozaki, H; Fujimoto, T; Tagusari, O; Kitamura, M

    1993-01-01

    A new intraventricular axial flow blood pump has been designed and developed as a totally implantable left ventricular assist device (LVAD). This pump consists of an impeller combined with a guide-vane, a tube housing, and a DC motor. The pump is introduced into the LV cavity through the LV apex, and the outlet cannula is passed antegrade across the aortic valve. Blood is withdrawn from the LV through the inlet ports at the pump base, and discharged to the ascending aorta. Our newly developed axial flow pump system has the following advantages: 1) it is a simple and compact system, 2) minimal blood stasis both in the device and the LV cavity, 3) minimal blood contacting surface of the pump, 4) easy accessibility with a less invasive surgical procedure, and 5) low cost. A pump flow > 5 L/min was obtained against 100 mmHg differential pressure in the mock circulatory system. The pump could produce a passive pulsatile flow effect with a beating heart more efficiently than other non-pulsatile pumps because of minimal pressure drop and inertia along the bypass tract. Anatomic fit studies using dissected hearts of dilated cardiomyopathy (DCM) cadavers showed that this pump could smoothly pass through the aortic valve without any interference with mitral valve function. Recently, a dynamic pressure groove bearing and a miniature lip seal have been developed. The dynamic pressure groove bearing has a simple structure and acts as a pressure resistant sealing mechanism.(ABSTRACT TRUNCATED AT 250 WORDS)

  6. Increased cerebral blood flow in preeclampsia with magnetic resonance imaging

    NARCIS (Netherlands)

    Zeeman, GG; Hatab, MR; Twickler, DM

    2004-01-01

    Objective: The purpose of this study was to compare third trimester and nonpregnant cerebral blood flow of women with preeclampsia to normotensive control subjects with the use of magnetic resonance imaging techniques. Study design: Nine normotensive pregnant women and 12 untreated women with preecl

  7. Patterns of regional cerebral blood flow in acute stroke

    DEFF Research Database (Denmark)

    Olsen, T S; Skriver, E B

    1981-01-01

    In a consecutive group of 56 stroke patients the regional cerebral blood flow was measured within 84 hours after stroke. A 254 multidetector scintillation camera and the intracarotid Xenon-133 injection method was used to study rCBF. Typical rCBF-patterns are described and compared to the findings...

  8. Simple technique for measuring relative renal blood flow

    International Nuclear Information System (INIS)

    To determine whether externally monitored early renal uptake of 131I-hippurate is proportional to renal blood flow, the renal uptake of 131-hippurate at 1 to 2 min after injection was compared with the renal accumulation of radioactive carbonized microspheres in dogs. A renal artery catheter equipped with a balloon was used to decrease renal blood flow unilaterally. One minute after the intravenous injection of 100 μCi of 131I-hippurate, about 1 μCi of either 85Sr- or 95Nb-labeled carbon microspheres was injected into the left ventricle. Radioactivity was measured over both kidneys. The total radioactivity within each kidney region of interest was corrected for background and integrated over the 1 to 2 min interval after injection. Thirteen measurements of relative renal blood flow were made for seven dogs. The dogs were then killed and both kidneys were excised and counted for the radioactivity of the microspheres. The 1 to 2-min relative renal uptake of 131I-hippurate correlated well with relative microsphere uptake, suggesting that relative renal blood flow can be simply determined from the external measurements of renal uptake of 131I-hippurate

  9. Whole-body vibration dosage alters leg blood flow.

    NARCIS (Netherlands)

    Lythgo, N.; Eser, P.; Groot, P.C.E. de; Galea, M.

    2009-01-01

    The effect of whole-body vibration dosage on leg blood flow was investigated. Nine healthy young adult males completed a set of 14 random vibration and non-vibration exercise bouts whilst squatting on a Galileo 900 plate. Six vibration frequencies ranging from 5 to 30 Hz (5 Hz increments) were used

  10. Splanchnic blood flow and hepatic glucose production in exercising humans

    DEFF Research Database (Denmark)

    Bergeron, R; Kjaer, M; Simonsen, L;

    2001-01-01

    The study examined the implication of the renin-angiotensin system (RAS) in regulation of splanchnic blood flow and glucose production in exercising humans. Subjects cycled for 40 min at 50% maximal O(2) consumption (VO(2 max)) followed by 30 min at 70% VO(2 max) either with [angiotensin...

  11. Age and gender related differences in aortic blood flow

    DEFF Research Database (Denmark)

    Traberg, Marie Sand; Pedersen, Mads Møller; Hemmsen, Martin Christian;

    2012-01-01

    The abdominal aorta (AA) is predisposed to development of abdominal aneurysms (AAA), a focal dilatation of the artery with fatal consequences if left untreated. The blood flow patterns in the AA is thought to play an important role in the development of AAA. The purpose of this work...

  12. Influence of blood flow on the coagulation cascade

    DEFF Research Database (Denmark)

    The influence of diffusion and convetive flows on the blood coagulation cascade is investigated for a controlled perfusion experiment. We present a cartoon model and reaction schemes for parts of the coagulation cascade with sunsequent set up of a mathematical model in two space dimensions plus one...

  13. A VARIATIONAL MODEL FOR 2-D MICROPOLAR BLOOD FLOW

    Institute of Scientific and Technical Information of China (English)

    He Ji-huan

    2003-01-01

    The micropolar fluid model is an essential generalization of the well-established Navier-Stokes model in the sense that it takes into account the microstructure of the fluid.This paper is devolted to establishing a variational principle for 2-D incompressible micropolar blood flow.

  14. Impaired endothelial function and blood flow in repetitive strain injury

    NARCIS (Netherlands)

    Brunnekreef, J.J.; Benda, N.M.M.; Schreuder, T.H.A.; Hopman, M.T.E.; Thijssen, D.H.J.

    2012-01-01

    Repetitive Strain Injury (RSI) is a disabling upper extremity overuse injury that may be associated with pathophysiological changes in the vasculature. In this study we investigated whether RSI is associated with endothelial dysfunction and impaired exercise-induced blood flow in the affected forear

  15. Haemodialysis decreases finger pressures independent of artificial kidney blood flow.

    NARCIS (Netherlands)

    Hoek, F. van; Scheltinga, M.R.M.; Houterman, S.; Beerenhout, C.H.

    2010-01-01

    BACKGROUND: During haemodialysis, some patients experience intensification of symptoms of haemodialysis access-induced distal ischaemia. Aim of this study is to compare the effects of two different regimens of arterial blood flow in patients with an arteriovenous access. METHODS: A questionnaire ide

  16. Cerebral blood flow during static exercise in humans

    DEFF Research Database (Denmark)

    Rogers, H B; Schroeder, T; Secher, N H;

    1990-01-01

    Cerebral blood flow (CBF) was determined in humans at rest and during four consecutive unilateral static contractions of the knee extensors. Each contraction was maintained for 3 min 15 s with the subjects in a semisupine position. The contractions corresponded to 8, 16, 24, and 32% of the maxima...

  17. Longitudinal Cerebral Blood Flow Changes during Speech in Hereditary Ataxia

    Science.gov (United States)

    Sidtis, John J.; Strother, Stephen C.; Naoum, Ansam; Rottenberg, David A.; Gomez, Christopher

    2010-01-01

    The hereditary ataxias constitute a group of degenerative diseases that progress over years or decades. With principal pathology involving the cerebellum, dysarthria is an early feature of many of the ataxias. Positron emission tomography was used to study regional cerebral blood flow changes during speech production over a 21 month period in a…

  18. Velocity estimation using synthetic aperture imaging [blood flow

    DEFF Research Database (Denmark)

    Nikolov, Svetoslav; Jensen, Jørgen Arendt

    2001-01-01

    Presented an approach for synthetic aperture blood flow ultrasound imaging. Estimates with a low bias and standard deviation can be obtained with as few as eight emissions. The performance of the new estimator is verified using both simulations and measurements. The results demonstrate that a fully...

  19. Cerebral blood flow in patients with dementia of Alzheimer's type

    DEFF Research Database (Denmark)

    Postiglione, A; Lassen, N A; Holman, B L

    1993-01-01

    In the normal brain as well as in Alzheimer's disease (AD), regional cerebral blood flow (CBF) is coupled to metabolic demand and, therefore, changes in CBF reflect variations in neuronal metabolism. The use of radionuclide techniques, such as positron emission tomography (PET) and single photon...

  20. Ascending aortic blood flow dynamics following intense exercise.

    Science.gov (United States)

    Kilgour, R D; Sellers, W R

    1990-10-01

    The purpose of this study was to compare and contrast aortic blood flow kinetics during recovery from intense aerobic (maximal oxygen uptake test) and anaerobic (Wingate anaerobic power test) exercise. Fifteen healthy male subjects (VO2max = 56.1 +/- 5.8 mk/kg/min) participated in this study. Beat-to-beat peak aortic blood flow velocity (pkV) and acceleration (pkA) measurements were obtained by placing a 3.0 MHz continuous-wave ultrasonic transducer on the suprasternal notch at rest and during recovery (immediately post-exercise, 2.5 min, and 5.0 min) following the two exercise conditions. Peak velocity and acceleration significantly increased (p less than 0.01) from rest to immediately post-exercise and remained elevated throughout the 5-min recovery period. No differences were observed between the aerobic and anaerobic tests. Stroke distance significantly declined (p less than 0.01) immediately following exercise and progressively rose during the 5-min recovery period. The results indicate that: 1) aortic blood flow kinetics remained elevated during short-term recovery, and 2) intense aerobic and anaerobic exercise exhibit similar post-exercise aortic blood flow kinetics. PMID:2262232

  1. Coded ultrasound for blood flow estimation using subband processing

    DEFF Research Database (Denmark)

    Gran, Fredrik; Udesen, Jesper; Nielsen, Michael bachmann;

    2007-01-01

    This paper further investigates the use of coded excitation for blood flow estimation in medical ultrasound. Traditional autocorrelation estimators use narrow-band excitation signals to provide sufficient signal-to-noise-ratio (SNR) and velocity estimation performance. In this paper, broadband co...

  2. Coded ultrasound for blood flow estimation using subband processing

    DEFF Research Database (Denmark)

    Gran, F.; Udesen, J.; Jensen, J.A.;

    2008-01-01

    This paper investigates the use of coded excitation for blood flow estimation in medical ultrasound. Traditional autocorrelation estimators use narrow-band excitation signals to provide sufficient signal-to-noise-ratio (SNR) and velocity estimation performance. In this paper, broadband coded sign...

  3. Oscillations and chaos in renal blood flow control

    DEFF Research Database (Denmark)

    Holstein-Rathlou, N H

    1993-01-01

    In normotensive, halothane-anesthetized rats, oscillations can be found both in the single-nephron blood flow and in the tubular pressure. Experimental data and computer simulations support the hypothesis that the oscillations are caused by the tubuloglomerular feedback (TGF) mechanism. Model...

  4. Results of Pancreatic Blood Shunting into the Systemic Blood Flow in Insulin-Dependent Diabetics

    OpenAIRE

    Galperin, E. I.; Diuzheva, T. G.; Petrovsky, P. F.; A. Yu. Chevokin; Dokuchayev, K. V.; Rabinovich, S. E.; Gitel, E. P.; Kuzovlev, N. F.; Platonov, L. V.

    1996-01-01

    A new surgical method of treating patients with unstable insulin-dependent diabetes (IDD) has been developed-that of surgically shunting pancreatic blood into the systemic blood flow with the purpose of creating a more optimal interaction of subcutaneously administered insulin and pancreas-secreted glucagon. The long term results of the operation depend on the patency of a splenorenal anastomosis. This has been studied by following up 137 patients over periods from half a year to three years....

  5. A hemolysis study of an intravascular blood cooling system for localized organ tissue cooling.

    Science.gov (United States)

    Merrill, T L; Mingin, T; Merrill, D R; Botbyl, J; Akers, J E

    2013-01-01

    Therapeutic hypothermia can reduce both ischemic and reperfusion injury arising after strokes and heart attacks. New localized organ cooling systems offer a way to reduce tissue damage more effectively with fewer side effects. To assess initial blood safety of our new organ cooling system, the CoolGuide Cooling System (CCS), we investigated safe operating conditions and configurations from a hemolysis perspective. The CCS consists of a peristaltic pump, a custom-built external heat exchanger, a chiller, biocompatible polyvinyl cellulose (PVC) tubing, and a control console. The CCS cools and circulates autologous blood externally and re-delivers cooled blood to the patient through a conventional catheter inserted directly into the organ at risk. Catheter configurations used included: a 7F guide catheter only, a 7F guide with a 0.038" wire inserted through the center and advanced 2 cm distal to the catheter distal tip, a 6F guide catheter only and a 6F guide with a 0.014" guidewire similarly inserted through the center. Using porcine blood, an in vitro test rig was used to measure the degree of hemolysis generation, defined as the percentage change in free hemoglobin, adjusted for total hemoglobin and hematocrit, between exiting and entering blood. The highest degree of hemolysis generation was 0.11±0.04%, based on the average behavior with a 6F catheter and a 0.014" guidewire configuration at a blood flow rate of approximately 130 mL/min. In terms of average percentage free hemoglobin exiting the system, based on total hemoglobin, the highest value measured was 0.17%±0.03%, using this 6F and 0.014" guidewire configuration. This result is significantly below the most stringent European guideline of 0.8% used for blood storage and transfusion. This study provides initial evidence showing hemolysis generation arising from the CoolGuide Cooling System is likely to be clinically insignificant. PMID:23047283

  6. Effect of spinal cord compression on local vascular blood flow and perfusion capacity.

    Directory of Open Access Journals (Sweden)

    Mohammed Alshareef

    Full Text Available Spinal cord injury (SCI can induce prolonged spinal cord compression that may result in a reduction of local tissue perfusion, progressive ischemia, and potentially irreversible tissue necrosis. Due to the combination of risk factors and the varied presentation of symptoms, the appropriate method and time course for clinical intervention following SCI are not always evident. In this study, a three-dimensional finite element fluid-structure interaction model of the cervical spinal cord was developed to examine how traditionally sub-clinical compressive mechanical loads impact spinal arterial blood flow. The spinal cord and surrounding dura mater were modeled as linear elastic, isotropic, and incompressible solids, while blood was modeled as a single-phased, incompressible Newtonian fluid. Simulation results indicate that anterior, posterior, and anteroposterior compressions of the cervical spinal cord have significantly different ischemic potentials, with prediction that the posterior component of loading elevates patient risk due to the concomitant reduction of blood flow in the arterial branches. Conversely, anterior loading compromises flow through the anterior spinal artery but minimally impacts branch flow rates. The findings of this study provide novel insight into how sub-clinical spinal cord compression could give rise to certain disease states, and suggest a need to monitor spinal artery perfusion following even mild compressive loading.

  7. Effect of spinal cord compression on local vascular blood flow and perfusion capacity.

    Science.gov (United States)

    Alshareef, Mohammed; Krishna, Vibhor; Ferdous, Jahid; Alshareef, Ahmed; Kindy, Mark; Kolachalama, Vijaya B; Shazly, Tarek

    2014-01-01

    Spinal cord injury (SCI) can induce prolonged spinal cord compression that may result in a reduction of local tissue perfusion, progressive ischemia, and potentially irreversible tissue necrosis. Due to the combination of risk factors and the varied presentation of symptoms, the appropriate method and time course for clinical intervention following SCI are not always evident. In this study, a three-dimensional finite element fluid-structure interaction model of the cervical spinal cord was developed to examine how traditionally sub-clinical compressive mechanical loads impact spinal arterial blood flow. The spinal cord and surrounding dura mater were modeled as linear elastic, isotropic, and incompressible solids, while blood was modeled as a single-phased, incompressible Newtonian fluid. Simulation results indicate that anterior, posterior, and anteroposterior compressions of the cervical spinal cord have significantly different ischemic potentials, with prediction that the posterior component of loading elevates patient risk due to the concomitant reduction of blood flow in the arterial branches. Conversely, anterior loading compromises flow through the anterior spinal artery but minimally impacts branch flow rates. The findings of this study provide novel insight into how sub-clinical spinal cord compression could give rise to certain disease states, and suggest a need to monitor spinal artery perfusion following even mild compressive loading. PMID:25268384

  8. In vitro validation of volumetric blood flow measurement using Doppler flow wire.

    Science.gov (United States)

    Jenni, R; Kaufmann, P A; Jiang, Z; Attenhofer, C; Linka, A; Mandinov, L

    2000-10-01

    Determination of any volumetric blood flow requires assessment of mean blood flow velocity and vessel cross-sectional area. For evaluation of coronary blood flow and flow reserve, however, assessment of average peak velocity alone is widely used, but changes in velocity profile and vessel area are not taken into account. We studied the feasibility of a new method for calculation of volumetric blood flow by Doppler power using a Doppler flow wire. An in vitro model with serially connected silicone tubes of known lumen diameters (1.5, 2.0, 2.5, 3.0, 3.5 and 4.0 mm) and pulsatile blood flow ranging from 10 to 200 mL/min was used. A Doppler flow wire was connected to a commercially available Doppler system (FloMap(R), Cardiometrics) for online calculation of the zeroth (M(0)) and the first (M(1)) Doppler moment, as well as mean flow velocity (V(m)). Two different groups of sample volumes (at different gate depths) were used: 1. two proximal sample volumes lying completely within the vessel were required to evaluate the effect of scattering and attenuation on Doppler power, and 2. distal sample volumes intersecting completely the vessel lumen to assess the vessel cross-sectional area. Area (using M(0)) and V(m) (using M(1)/M(0)) obtained from the distal gates were corrected for scattering and attenuation by the data obtained from the proximal gates, allowing calculation of absolute volumetric flow. These results were compared to the respective time collected flow. Correlation between time collected and Doppler-derived flow measurements was 0.98 (p measurements in each individual tube. The mean paired flow difference between the two techniques was 1.5 +/- 9.0 mL/min (ns). Direct volumetric blood flow measurement from received Doppler power using a Doppler flow wire system is feasible. This technique may potentially be of great clinical value because it allows an accurate assessment of coronary flow and flow reserve with a commercially available flow wire system. PMID

  9. The blood-tendon barrier: identification and characterisation of a novel tissue barrier in tendon blood vessels.

    Science.gov (United States)

    Lehner, C; Gehwolf, R; Ek, J C; Korntner, S; Bauer, H; Bauer, H C; Traweger, A; Tempfer, H

    2016-01-01

    Tissue barriers function as "gate keepers" between different compartments (usually blood and tissue) and are formed by specialised membrane-associated proteins, localising to the apicolateral plasma membrane domain of epithelial and endothelial cells. By sealing the paracellular space, the free diffusion of solutes and molecules across epithelia and endothelia is impeded. Thereby, tissue barriers contribute to the establishment and maintenance of a distinct internal and external environment, which is crucial during organ development and allows maintenance of an organ-specific homeostatic milieu. So far, various epithelial and endothelial tissue barriers have been described, including the blood-brain barrier, the blood-retina barrier, the blood-testis barrier, the blood-placenta barrier, and the cerebrospinal fluid (CSF)-brain barrier, which are vital for physiological function and any disturbance of these barriers can result in severe organ damage or even death. Here, we describe the identification of a novel barrier, located in the vascular bed of tendons, which we term the blood-tendon barrier (BTB). By using immunohistochemistry, transmission electron microscopy, and tracer studies we demonstrate the presence of a functional endothelial barrier within tendons restricting the passage of large blood-borne molecules into the surrounding tendon tissue. We further provide in vitro evidence that the BTB potentially contributes to the creation of a distinct internal tissue environment impacting upon the proliferation and differentiation of tendon-resident cells, effects which might be fundamental for the onset of tendon pathologies. PMID:27227787

  10. Mechanical axial flow blood pump to support cavopulmonary circulation.

    Science.gov (United States)

    Throckmorton, A L; Kapadia, J; Madduri, D

    2008-11-01

    We are developing a collapsible, percutaneously inserted, axial flow blood pump to support the cavopulmonary circulation in infants with a failing single ventricle physiology. An initial design of the impeller for this axial flow blood pump was performed using computational fluid dynamics analysis, including pressure-flow characteristics, scalar stress estimations, blood damage indices, and fluid force predictions. A plastic prototype was constructed for hydraulic performance testing, and these experimental results were compared with the numerical predictions. The numerical predictions and experimental findings of the pump performance demonstrated a pressure generation of 2-16 mm Hg for 50-750 ml/min over 5,500-7,500 RPM with deviation found at lower rotational speeds. The axial fluid forces remained below 0.1 N, and the radial fluid forces were determined to be virtually zero due to the centered impeller case. The scalar stress levels remained below 250 Pa for all operating conditions. Blood damage analysis yielded a mean residence time of the released particles, which was found to be less than 0.4 seconds for both flow rates that were examined, and a maximum residence time was determined to be less than 0.8 seconds. We are in the process of designing a cage with hydrodynamically shaped filament blades to act as a diffuser and optimizing the impeller blade shape to reduce the flow vorticity at the pump outlet. This blood pump will improve the clinical treatment of patients with failing Fontan physiology and provide a unique catheter-based therapeutic approach as a bridge to recovery or transplantation. PMID:19089799

  11. The effect of lung orientation on functional imaging of blood flow

    Science.gov (United States)

    Burrowes, Kelly S.; Tawhai, Merryn H.

    2007-03-01

    Advancing technology has enabled rapid improvements in imaging and image processing techniques providing increasing amounts of structural and functional information. While these imaging modalities now offer a wealth of information about function within the body in health and disease certain limitations remain. We believe these can largely be addressed through a combined medical imaging - computational modeling approach. For example, imaging may only be performed in the prone or supine postures but humans function naturally in the upright position. We have developed an image-based computational model of coupled tissue mechanics and pulmonary blood flow to enable predictions of pulmonary perfusion in various postures and lung volumes. Lung and vascular geometries are derived using a combination of imaging reconstruction and computational algorithms. Solution of finite deformation equations provides predictions of tissue deformation and internal pressure distributions within the lung parenchyma. By embedding vascular models within the lung volume we obtain a coupled model of blood vessel deformation as a result of changes in lung volume. A 1D form of the Navier-Stokes flow equations are solved within the vascular model to predict perfusion. Tissue pressures calculated from the mechanics model are incorporated into the vascular constitutive pressure-radius relationship. Results demonstrated a relatively consistent flow distribution in all postures indicating the large influence of branching structure on flow distribution. It is hoped that this modeling approach may provide insights to enable interpolation of imaging measurements in alternate postures and lung volumes and enable an increased understanding of the mechanisms influencing pulmonary perfusion distribution.

  12. Influence of Gravity on Blood Volume and Flow Distribution

    Science.gov (United States)

    Pendergast, D.; Olszowka, A.; Bednarczyk, E.; Shykoff, B.; Farhi, L.

    1999-01-01

    In our previous experiments during NASA Shuttle flights SLS 1 and 2 (9-15 days) and EUROMIR flights (30-90 days) we observed that pulmonary blood flow (cardiac output) was elevated initially, and surprisingly remained elevated for the duration of the flights. Stroke volume increased initially and then decreased, but was still above 1 Gz values. As venous return was constant, the changes in SV were secondary to modulation of heart rate. Mean blood pressure was at or slightly below 1 Gz levels in space, indicating a decrease in total peripheral resistance. It has been suggested that plasma volume is reduced in space, however cardiac output/venous return do not return to 1 Gz levels over the duration of flight. In spite of the increased cardiac output, central venous pressure was not elevated in space. These data suggest that there is a change in the basic relationship between cardiac output and central venous pressure, a persistent "hyperperfusion" and a re-distribution of blood flow and volume during space flight. Increased pulmonary blood flow has been reported to increase diffusing capacity in space, presumably due to the improved homogeneity of ventilation and perfusion. Other studies have suggested that ventilation may be independent of gravity, and perfusion may not be gravity- dependent. No data for the distribution of pulmonary blood volume were available for flight or simulated microgravity. Recent studies have suggested that the pulmonary vascular tree is influenced by sympathetic tone in a manner similar to that of the systemic system. This implies that the pulmonary circulation is dilated during microgravity and that the distribution of blood flow and volume may be influenced more by vascular control than by gravity. The cerebral circulation is influenced by sympathetic tone similarly to that of the systemic and pulmonary circulations; however its effects are modulated by cerebral autoregulation. Thus it is difficult to predict if cerebral perfusion is

  13. Assessment of maternal cerebral blood flow in patients with preeclampsia

    Directory of Open Access Journals (Sweden)

    Mandić Vesna

    2005-01-01

    Full Text Available Introduction Systemic vasoconstrktion in preeclamptic patients increases vascular resistance, and is manifested by increased arterial blood flow velocity. The aim of the study is to evaluate if there is a change of Doppler indices in maternal medial cerbral artery (MCA in severe preeclampsia due to: 1 severity of clinical symptoms, 2 the beginning of eclamptic attack and 3 the application of anticonvidsive therapy. Material and methods A prospective clinical study included 92 pregnant women, gestational age 28-36 weeks. They were divided into three groups: normotensive (n=30, mild preeclampsia (n=33, and severe preeclampsia (n=29. We investigated maternal cerebral circulation by assessing the MCA. We registrated: pulsatility index (Pi, resistance index (Ri, Systolic/diastolic ratio (S/D, and the maximum systolic, end diastolic and medium velocity. Patients with severe preeclampsia were divided into two subgroups: subgroup 1 included patients without symptoms of threatening eclampsia (n=18; 62.06%; while subgroup 2 included those with symptoms of preeclampsia (n=11; 37.94%. All patients with severe preeclampsia were treated with magnesium sulfate (MgSO4, and cerebral blood flow was measured before and after the treatment. Statistical analysis was done by oneway ANOVA, Student t-test and t-paired sample test. The difference was considered to be significant if p < 0.05. Results Significantly increased Pi, Ri and all velocities were established in the group of patients with severe preeclampsia compared with the other two groups. In the group with severe preeclamsia we registrated significantly increased values of all velocities (patients with signs of threatening eclampsia. After MgSO4 treatment in patients with severe preeclampsia significantly decreased values of Pi, Ri, S/D ratio and all velocities were registered. Discussion In the studied group of patients with severe preclampsia we found increased velocity values, Pi and Ri, especially in

  14. Skeletal blood flow, iliac histomorphometry, and strontium kinetics in osteoporosis: a relationship between blood flow and corrected apposition rate

    Energy Technology Data Exchange (ETDEWEB)

    Reeve, J.; Arlot, M.; Wootton, R.; Edouard, C.; Tellez, M.; Hesp, R.; Green, J.R.; Meunier, P.J.

    1988-06-01

    In 20 untreated patients with idiopathic or postmenopausal osteoporosis, kinetic studies of skeletal blood flow (using /sup 18/F) and bone turnover (using /sup 85/Sr) were combined with dynamic histomorphometry performed on transiliac biopsies taken within 6 weeks of each other. In 8 patients the combined studies were repeated after treatment. A further 5 patients were studied only while receiving treatment. As expected, skeletal blood flow measured by /sup 18/F correlated with an index of /sup 85/Sr uptake into the exchangeable pools of bone. Additionally and independently, skeletal blood flow correlated with an index of the work rate of the osteoblasts in each multicellular unit of bone (the corrected apposition rate of Parfitt). These correlations were statistically significant in both the untreated patients (P less than 0.05) and the whole group (P less than 0.001). Further indices related to bone turnover at the level of the skeleton as a whole were significantly associated with skeletal blood flow only in the combined group.

  15. Pulsatile microvascular blood flow imaging by short-time Fourier transform analysis of ultrafast laser holographic interferometry

    CERN Document Server

    Puyo, L; Rancillac, A; Simonutti, M; Paques, M; Sahel, J A; Fink, M; Atlan, M

    2015-01-01

    We report on wide-field imaging of pulsatile microvascular blood flow in the exposed cerebral cortex of a mouse by holographic interferometry. We recorded interferograms of laser light backscattered by the tissue, beating against an off-axis reference beam with a 50 kHz framerate camera. Videos of local Doppler contrasts were rendered numerically by Fresnel transformation and short-time Fourier transform analysis. This approach enabled instantaneous imaging of pulsatile blood flow contrasts in superficial blood vessels over 256 x 256 pixels with a spatial resolution of 10 microns and a temporal resolution of 20 ms.

  16. Tissue Factor, Blood Coagulation, and Beyond: An Overview

    Directory of Open Access Journals (Sweden)

    Arthur J. Chu

    2011-01-01

    Full Text Available Emerging evidence shows a broad spectrum of biological functions of tissue factor (TF. TF classical role in initiating the extrinsic blood coagulation and its direct thrombotic action in close relation to cardiovascular risks have long been established. TF overexpression/hypercoagulability often observed in many clinical conditions certainly expands its role in proinflammation, diabetes, obesity, cardiovascular diseases, angiogenesis, tumor metastasis, wound repairs, embryonic development, cell adhesion/migration, innate immunity, infection, pregnancy loss, and many others. This paper broadly covers seminal observations to discuss TF pathogenic roles in relation to diverse disease development or manifestation. Biochemically, extracellular TF signaling interfaced through protease-activated receptors (PARs elicits cellular activation and inflammatory responses. TF diverse biological roles are associated with either coagulation-dependent or noncoagulation-mediated actions. Apparently, TF hypercoagulability refuels a coagulation-inflammation-thrombosis circuit in “autocrine” or “paracrine” fashions, which triggers a wide spectrum of pathophysiology. Accordingly, TF suppression, anticoagulation, PAR blockade, or general anti-inflammation offers an array of therapeutical benefits for easing diverse pathological conditions.

  17. Spatial mapping of blood flow and oxygen consumption in the human calf muscle using near-infrared spectroscopy

    Science.gov (United States)

    Fantini, Sergio; Hoimes, Matthew L.; Casavola, Claudia; Franceschini, Maria-Angela

    2001-05-01

    We have designed a new optical probe to perform spatially resolved measurements of blood flow and oxygen consumption over an area of about 4 x 4 cm2 of the lateral gastrocnemius muscle (calf muscle) of human subjects. The blood flow and the oxygen consumption were measured non- invasively with frequency-domain, near-infrared spectroscopy from the maximum rate of increase of the oxy- and deoxy- hemoglobin concentrations in the muscle during venous occlusion. In a preliminary test on one subject, involving measurements at rest and after exercise, we have found that the spatial variability of the measured blood flow and oxygen consumption is significantly greater than the variability of repeated measurements at a given tissue location. We have also observed a strong spatial dependence of the exercise-induced increase in blood flow and oxygen consumption.

  18. Laser doppler blood flow imaging using a CMOS imaging sensor with on-chip signal processing.

    Science.gov (United States)

    He, Diwei; Nguyen, Hoang C; Hayes-Gill, Barrie R; Zhu, Yiqun; Crowe, John A; Gill, Cally; Clough, Geraldine F; Morgan, Stephen P

    2013-01-01

    The first fully integrated 2D CMOS imaging sensor with on-chip signal processing for applications in laser Doppler blood flow (LDBF) imaging has been designed and tested. To obtain a space efficient design over 64 × 64 pixels means that standard processing electronics used off-chip cannot be implemented. Therefore the analog signal processing at each pixel is a tailored design for LDBF signals with balanced optimization for signal-to-noise ratio and silicon area. This custom made sensor offers key advantages over conventional sensors, viz. the analog signal processing at the pixel level carries out signal normalization; the AC amplification in combination with an anti-aliasing filter allows analog-to-digital conversion with a low number of bits; low resource implementation of the digital processor enables on-chip processing and the data bottleneck that exists between the detector and processing electronics has been overcome. The sensor demonstrates good agreement with simulation at each design stage. The measured optical performance of the sensor is demonstrated using modulated light signals and in vivo blood flow experiments. Images showing blood flow changes with arterial occlusion and an inflammatory response to a histamine skin-prick demonstrate that the sensor array is capable of detecting blood flow signals from tissue. PMID:24051525

  19. Laser Doppler Blood Flow Imaging Using a CMOS Imaging Sensor with On-Chip Signal Processing

    Science.gov (United States)

    He, Diwei; Nguyen, Hoang C.; Hayes-Gill, Barrie R.; Zhu, Yiqun; Crowe, John A.; Gill, Cally; Clough, Geraldine F.; Morgan, Stephen P.

    2013-01-01

    The first fully integrated 2D CMOS imaging sensor with on-chip signal processing for applications in laser Doppler blood flow (LDBF) imaging has been designed and tested. To obtain a space efficient design over 64 × 64 pixels means that standard processing electronics used off-chip cannot be implemented. Therefore the analog signal processing at each pixel is a tailored design for LDBF signals with balanced optimization for signal-to-noise ratio and silicon area. This custom made sensor offers key advantages over conventional sensors, viz. the analog signal processing at the pixel level carries out signal normalization; the AC amplification in combination with an anti-aliasing filter allows analog-to-digital conversion with a low number of bits; low resource implementation of the digital processor enables on-chip processing and the data bottleneck that exists between the detector and processing electronics has been overcome. The sensor demonstrates good agreement with simulation at each design stage. The measured optical performance of the sensor is demonstrated using modulated light signals and in vivo blood flow experiments. Images showing blood flow changes with arterial occlusion and an inflammatory response to a histamine skin-prick demonstrate that the sensor array is capable of detecting blood flow signals from tissue. PMID:24051525

  20. Laser doppler blood flow imaging using a CMOS imaging sensor with on-chip signal processing.

    Science.gov (United States)

    He, Diwei; Nguyen, Hoang C; Hayes-Gill, Barrie R; Zhu, Yiqun; Crowe, John A; Gill, Cally; Clough, Geraldine F; Morgan, Stephen P

    2013-09-18

    The first fully integrated 2D CMOS imaging sensor with on-chip signal processing for applications in laser Doppler blood flow (LDBF) imaging has been designed and tested. To obtain a space efficient design over 64 × 64 pixels means that standard processing electronics used off-chip cannot be implemented. Therefore the analog signal processing at each pixel is a tailored design for LDBF signals with balanced optimization for signal-to-noise ratio and silicon area. This custom made sensor offers key advantages over conventional sensors, viz. the analog signal processing at the pixel level carries out signal normalization; the AC amplification in combination with an anti-aliasing filter allows analog-to-digital conversion with a low number of bits; low resource implementation of the digital processor enables on-chip processing and the data bottleneck that exists between the detector and processing electronics has been overcome. The sensor demonstrates good agreement with simulation at each design stage. The measured optical performance of the sensor is demonstrated using modulated light signals and in vivo blood flow experiments. Images showing blood flow changes with arterial occlusion and an inflammatory response to a histamine skin-prick demonstrate that the sensor array is capable of detecting blood flow signals from tissue.

  1. Effects of Sevoflurane and Propofol on Organ Blood Flow in Left Ventricular Assist Devices in Pigs

    Directory of Open Access Journals (Sweden)

    Paloma Morillas-Sendín

    2015-01-01

    Full Text Available The aim of this study was to assess the effect of sevoflurane and propofol on organ blood flow in a porcine model with a left ventricular assist device (LVAD. Ten healthy minipigs were divided into 2 groups (5 per group according to the anesthetic received (sevoflurane or propofol. A Biomedicus centrifugal pump was implanted. Organ blood flow (measured using colored microspheres, markers of tissue injury, and hemodynamic parameters were assessed at baseline (pump off and after 30 minutes of partial support. Blood flow was significantly higher in the brain (both frontal lobes, heart (both ventricles, and liver after 30 minutes in the sevoflurane group, although no significant differences were recorded for the lung, kidney, or ileum. Serum levels of alanine aminotransferase and total bilirubin were significantly higher after 30 minutes in the propofol group, although no significant differences were detected between the groups for other parameters of liver function, kidney function, or lactic acid levels. The hemodynamic parameters were similar in both groups. We demonstrated that, compared with propofol, sevoflurane increases blood flow in the brain, liver, and heart after implantation of an LVAD under conditions of partial support.

  2. Blood flow changes after unilateral carotid artery ligation monitored by optical coherence tomography

    Science.gov (United States)

    Ma, Yushu; Liang, Chengbo; Suo, Yanyan; Zhao, Yuqian; Wang, Yi; Xu, Tao; Wang, Ruikang; Ma, Zhenhe

    2016-03-01

    Unilateral carotid artery ligation which could induce adaptive improvement is a classic model that has been widely used to study pathology of ischemic disease. In those studies, blood flow is an important parameter to characterize the ischemia. Optical coherence tomography (OCT) is a powerful imaging modality which can provide depth resolved images in biological tissue with high spatial and temporal resolution. SPF rats was anesthetized with isoflurane and divided into two groups. In first group, bilateral carotid artery was surgically exposed, and then left carotid artery was ligated. Blood flow changes of the contralateral carotid artery was monitored using high speed spectral domain optical coherence tomography, including the absolute flow velocity and the flow volume. In the other group, skull window was opened at the ipsilateral cerebral cortex of ligation and blood supply of small artery was measured before and after the ligation. The measured results demonstrate the blood supply compensation process after unilateral carotid artery ligation. With the superiority of high resolution, OCT is an effective technology in monitoring results of carotid artery after ligation.

  3. Epidural blood flow and regression of sensory analgesia during continuous postoperative epidural infusion of bupivacaine

    DEFF Research Database (Denmark)

    Mogensen, T; Højgaard, L; Scott, N B;

    1988-01-01

    Epidural blood flow was measured in seven patients undergoing elective abdominal surgery during combined lumbar epidural and general anesthesia. After an initial dose of 20 ml plain bupivacaine 0.5%, a continuous epidural infusion of bupivacaine 0.5% (8 ml/hr) was given for 16 hours...... for postoperative pain relief. The epidural blood flow was measured by a local 133Xe clearance technique in which 15-35 MBq 133Xe diluted in 1 ml saline was injected through the epidural catheter on the day before surgery (no bupivacaine), 30 minutes after the initial dose of bupivacaine on the morning before...... surgery, and 8, 12, and 16 hours later during the continuous infusion. Initial blood flow was 6.0 +/- 0.7 ml/min per 100 g tissue (mean +/- SEM). After epidural bupivacaine, blood flow increased in all seven patients to 7.4 +/- 0.7 ml (P less than 0.02). Initial level of sensory analgesia was T4.5 +/- 0...

  4. Laser speckle contrast imaging of cerebral blood flow in humans during neurosurgery: a pilot clinical study

    Science.gov (United States)

    Parthasarathy, Ashwin B.; Weber, Erica L.; Richards, Lisa M.; Fox, Douglas J.; Dunn, Andrew K.

    2010-11-01

    Monitoring cerebral blood flow (CBF) during neurosurgery can provide important physiological information for a variety of surgical procedures. CBF measurements are important for assessing whether blood flow has returned to presurgical baseline levels and for assessing postsurgical tissue viability. Existing techniques for intraoperative monitoring of CBF based on magnetic resonance imaging are expensive and often impractical, while techniques such as indocyanine green angiography cannot produce quantitative measures of blood flow. Laser speckle contrast imaging (LSCI) is an optical technique that has been widely used to quantitatively image relative CBF in animal models in vivo. In a pilot clinical study, we adapted an existing neurosurgical operating microscope to obtain LSCI images in humans in real time during neurosurgery under baseline conditions and after bipolar cautery. Simultaneously recorded ECG waveforms from the patient were used to develop a filter that helped reduce measurement variabilities due to motion artifacts. Results from this study demonstrate the feasibility of using LSCI to obtain blood flow images during neurosurgeries and its capability to produce full field CBF image maps with excellent spatial resolution in real-time with minimal disruption to the surgical procedure.

  5. Laser Doppler Blood Flow Imaging Using a CMOS Imaging Sensor with On-Chip Signal Processing

    Directory of Open Access Journals (Sweden)

    Cally Gill

    2013-09-01

    Full Text Available The first fully integrated 2D CMOS imaging sensor with on-chip signal processing for applications in laser Doppler blood flow (LDBF imaging has been designed and tested. To obtain a space efficient design over 64 × 64 pixels means that standard processing electronics used off-chip cannot be implemented. Therefore the analog signal processing at each pixel is a tailored design for LDBF signals with balanced optimization for signal-to-noise ratio and silicon area. This custom made sensor offers key advantages over conventional sensors, viz. the analog signal processing at the pixel level carries out signal normalization; the AC amplification in combination with an anti-aliasing filter allows analog-to-digital conversion with a low number of bits; low resource implementation of the digital processor enables on-chip processing and the data bottleneck that exists between the detector and processing electronics has been overcome. The sensor demonstrates good agreement with simulation at each design stage. The measured optical performance of the sensor is demonstrated using modulated light signals and in vivo blood flow experiments. Images showing blood flow changes with arterial occlusion and an inflammatory response to a histamine skin-prick demonstrate that the sensor array is capable of detecting blood flow signals from tissue.

  6. Changes in Hepatic Blood Flow During Transcatheter Arterial Infusion with Heated Saline in Hepatic VX2 Tumor

    International Nuclear Information System (INIS)

    Purpose. This study evaluates the influence of transcatheter arterial infusion with heated saline on hepatic arterial and portal venous blood flows to tumor and normal hepatic tissues in a rabbit VX2 tumor model. Methods. All animal experiments were approved by the institutional animal care and use committee. Twenty rabbits with VX2 liver tumors were divided into the following two groups: (a) the treated group (n = 10), which received a 60 mL transarterial injection of 60 °C saline via the hepatic artery; (b) the control group (n = 10), which received a 60 mL injection of 37 °C saline via the hepatic artery. Using ultrasonography, the blood flows in both the portal vein and hepatic artery were measured, and the changes in the hemodynamic indices were recorded before and immediately after the injection. The changes in the tumor and normal liver tissues of the two groups were histopathologically examined by hematoxylin and eosin staining after the injection. Results. After the transcatheter arterial heated infusion, there was a decrease in the hepatic arterial blood flow to the tumor tissue, a significant decrease in the hepatic artery mean velocity (P < 0.05), and a significant increase in the resistance index (P < 0.05). On hematoxylin and eosin staining, there were no obvious signs of tissue destruction in the normal liver tissue or the tumor tissue after heated perfusion, and coagulated blood plasma was observed in the cavities of intratumoral blood vessels in the treated group. Conclusions. The changes in tumor blood flow in the rabbit VX2 tumor model were presumably caused by microthrombi in the tumor vessels, and the portal vein likely mediated the heat loss in normal liver tissue during the transarterial heated infusion.

  7. Ozone Therapy on Cerebral Blood Flow: A Preliminary Report

    Directory of Open Access Journals (Sweden)

    Bernardino Clavo

    2004-01-01

    Full Text Available Ozone therapy is currently being used in the treatment of ischemic disorders, but the underlying mechanisms that result in successful treatment are not well known. This study assesses the effect of ozone therapy on the blood flow in the middle cerebral and common carotid arteries. Seven subjects were recruited for the therapy that was performed by transfusing ozone-enriched autologous blood on 3 alternate days over 1 week. Blood flow quantification in the common carotid artery (n = 14 was performed using color Doppler. Systolic and diastolic velocities in the middle cerebral artery (n = 14 were estimated using transcranial Doppler. Ultrasound assessments were conducted at the following three time points: 1 basal (before ozone therapy, 2 after session #3 and 3 1 week after session #3. The common carotid blood flow had increased by 75% in relation to the baseline after session #3 (P < 0.001 and by 29% 1 week later (P = 0.039. In the middle cerebral artery, the systolic velocity had increased by 22% after session #3 (P = 0.001 and by 15% 1 week later (P = 0.035, whereas the diastolic velocity had increased by 33% after session #3 (P < 0.001 and by 18% 1 week later (P = 0.023. This preliminary Doppler study supports the clinical experience of achieving improvement by using ozone therapy in peripheral ischemic syndromes. Its potential use as a complementary treatment in cerebral low perfusion syndromes merits further clinical evaluation.

  8. Occlusion-free Blood Flow Animation with Wall Thickness Visualization.

    Science.gov (United States)

    Lawonn, Kai; Glaßer, Sylvia; Vilanova, Anna; Preim, Bernhard; Isenberg, Tobias

    2016-01-01

    We present the first visualization tool that combines pathlines from blood flow and wall thickness information. Our method uses illustrative techniques to provide occlusion-free visualization of the flow. We thus offer medical researchers an effective visual analysis tool for aneurysm treatment risk assessment. Such aneurysms bear a high risk of rupture and significant treatment-related risks. Therefore, to get a fully informed decision it is essential to both investigate the vessel morphology and the hemodynamic data. Ongoing research emphasizes the importance of analyzing the wall thickness in risk assessment. Our combination of blood flow visualization and wall thickness representation is a significant improvement for the exploration and analysis of aneurysms. As all presented information is spatially intertwined, occlusion problems occur. We solve these occlusion problems by dynamic cutaway surfaces. We combine this approach with a glyph-based blood flow representation and a visual mapping of wall thickness onto the vessel surface. We developed a GPU-based implementation of our visualizations which facilitates wall thickness analysis through real-time rendering and flexible interactive data exploration mechanisms. We designed our techniques in collaboration with domain experts, and we provide details about the evaluation of the technique and tool.

  9. Involvement of calcitonin gene-related peptide in migraine: regional cerebral blood flow and blood flow velocity in migraine patients

    DEFF Research Database (Denmark)

    Lassen, L.H.; Jacobsen, V.B.; Haderslev, P.A.;

    2008-01-01

    g/min) or placebo for 20 min was studied in 12 patients with migraine without aura outside attacks. Xenon-133 inhalation SPECT-determined regional cerebral blood flow (rCBF) and transcranial Doppler (TCD)-determined blood velocity (V-mean) in the middle cerebral artery (MCA), as well as the heart......Calcitonin gene-related peptide (CGRP)-containing nerves are closely associated with cranial blood vessels. CGRP is the most potent vasodilator known in isolated cerebral blood vessels. CGRP can induce migraine attacks, and two selective CGRP receptor antagonists are effective in the treatment...... of migraine attacks. It is therefore important to investigate its mechanism of action in patients with migraine. We here investigate the effects of intravenous human alpha-CGRP (h alpha CGRP) on intracranial hemodynamics. In a double-blind, cross-over study, the effect of intravenous infusion of haCGRP (2 mu...

  10. 超声动态评估组织灌注技术评价糖尿病患者肾脏皮质血流灌注%Evaluation of Renal Cortical Blood Flow in Patients with Diabetes by Dynamic Assessment of Tissue Perfusion

    Institute of Scientific and Technical Information of China (English)

    乔智蔚

    2016-01-01

    Objective To evaluate the effect of tissue perfusion technique in evaluating renal cortical blood flow in patients with diabetes mellitus.Methods Two patients with type 60 diabetes mellitus in our hospital from March 2013 to September 2015 were selected as the observation group. According to the glomerular filtration of the group:A group of 20 cases ( normal) , B group of 40 cases ( decreased) , the other 30 normal subjects as the control group. The group suffering from the use of color Doppler ul-trasound equipment, and the use of PixelFlux software for further analysis of the image and research.Results In the observation group ( a group) and the control group were compared, average perfusion intensity and the mean velocity of blood flow there were statistically significant differences ( P 0. 05);observation group B group and control group and were compared with each other and average perfusion intensity, average velocity of blood flow, tissue resistance index of P was less than 0.05. There is a statistically significant.Conclusion Dynamic ultrasound assessment in tissue perfusion technique can more accurately evaluate the ROI of flow parameters, so diabetic pa-tients accept dynamic ultrasound examination can clear the renal function, the treatment as soon as possible to determine, and improving the level of quality of life of patients has important significance.%目的:超声动态评估组织灌注技术用于评价糖尿病患者肾脏皮质血流灌注的效果。方法选择2013年3月—2015年9月期间该院收治的60例2型糖尿病患者作为观察组研究对象。按照其肾小球的过滤情况进行分组:A组20例(正常),B组40例(下降),另选择30名正常者作为对照组研究对象。该组患例采用彩超仪器,并使用PixelFlux软件对图像进行进一步的分析与研究。结果观察组A组与对照组相比较,平均灌注强度、平均血流速度均差异有统计学意义(P0.05);观察组B组与对照与患者相互

  11. Blood Flow Imaging in Maternal and Fetal Arteries and Veins

    Science.gov (United States)

    Ricci, S.; Urban, G.; Vergani, P.; Paidas, M. J.; Tortoli, P.

    Maternal and fetal blood circulation has been investigated for nearly a decade through ultrasound (US) techniques. Evaluation of the spectrogram related to a single sample volume has been proven valuable for the assessment of fetal well-being and for prediction of pregnancy complications. In this work, an alternative technique, called Multigate Spectral Doppler Analysis (MSDA), is proposed. In this approach, 128 sample volumes aligned along the same scan line are simultaneously investigated to detect the blood velocity profile with high resolution. Profiles obtained through MSDA reveal features not detectable with the standard US technique, thus representing a more accurate flow signature. Some preliminary illustrative results are reported here.

  12. Margination of leukocytes in blood flow through small tubes.

    Science.gov (United States)

    Goldsmith, H L; Spain, S

    1984-03-01

    Leukocyte margination in the vessels of the microcirculation has been attributed to a flow-dependent interaction with red cells. To determine the extent of this effect, experiments with human blood were done in 100- to 180-micron tubes to detect changes in cell distribution as a function of hematocrit and flow rate. Using a flow visualization technique, the leukocyte concentration distribution was determined in 45% ghost cell suspensions. Migration of cells toward the wall was observed at centerline velocities greater than 1 mm sec-1 and increased with increasing flow rate. The effect was probably due to a more rapid inward migration of ghosts than leukocytes because of fluid inertia and cell density differences. Experiments were therefore carried out in whole blood at hematocrits from 20 to 60%, measuring the number concentration of leukocytes and erythrocytes within the tube, nt, and comparing it to that in the infusing reservoir, no, (Fahraeus effect). At mean tube shear rates G less than 100 sec-1, nt/no less than 1 for both leukocytes and erythrocytes showing net migration of cells away from the wall, although at nearly all hematocrits there was an enrichment of leukocytes relative to erythrocytes in the tubes. At G less than 50 sec-1, nt/no remained less than 1 for erythrocytes but increased to greater than 1 for leukocytes showing migration toward the wall, the increase being greatest at 20% hematocrit in the 100-micron tubes. The nature of the effect was revealed by cine films which showed that, as the flow rate decreased, erythrocytes formed rouleaux which migrated inward creating a core and displacing leukocytes to the periphery. In control experiments using washed blood cells in phosphate buffer-albumin, nt/no less than 1 for both leukocytes and erythrocytes at all G and hematocrits, and leukocytes were now distributed. Cine films of washed blood confirmed that, in the absence of rouleaux, no significant inward migration of erythrocytes occurred. PMID

  13. Anisodamine augments mucosal blood flow during gut ischemia/reperfusion

    Institute of Scientific and Technical Information of China (English)

    Hu Sen; Sheng Zhiyong

    2002-01-01

    Objective: To determine if anisodamine is able to augment mucosal perfusion during gut ischemia-reperfusion (I/R). Methods: A jejunal sac was formed in Sprague Dawley rat. A Laser Doppler probe and a tonometer were inserted into the sac which was filled with saline. The superior mesenteric artery was occluded (SMAO) for 60minutes followed by 90 minutes of reperfusion. At the end of 60 minutes of SMAO, either 0.2mg/kg of anisodmine or dobutamine was injected into the jejunal sac. Laser Doppler mucosal blood flow and regional PCO2 (PrCO2) measurements were made. Results: Mucosal blood flow was significantly increased at 30,60 and 90 minutes of reperfusion (R30, R60, R90 ) when intraluminal anisodamine or dobutamine was introduced compared to intraluminal saline only (44±3.3)% or (48±4.1)% vs. (37±2.6) % at R30, (57±5.0)% or (56±4.7)% vs. (45±2.7)% at R60, (64±3.3) % or (56 ± 4.2) % vs. (48 ± 3.4) % at R90 , respectively P<0.05). Blood flow changes were also reflected by lowering of jejunal PrCO2 measurements after intraluminal anisodamine or dobutamine compared with that of the saline controls (41±3. 1)mmHg or (44±3.0)mmHg vs. (49±3.7) mmHg at R30 , (38±3.7)mmHg or (40±2. 1)mmHg vs. (47±3.8) mmHgat R60, (34±2.1) mmHg or (39± 3.0) mmHg vs. (46±3.4) mmHg at R90, respectively,P<0. 05). The most interesting finding was that there were significantly higher mucosal blood flow and lower jejunal PrCO2 in anisodamine group than those in dobutamine group at 90 minutes of reperfusion (64± 3.3) %vs. (56±4.2)% for blood flow or (34 ± 2.1)mmHg vs. (39 ± 3.0)mmHg for PrCO2, respectively, P<0.05),suggesting that anisodamine had more lasting effect on mucosal perfusion than dobutamine. Conclusions:Intraluminal anisodamine can augment mucosal blood flow during gut I/R, and it may provide the protective effect on gut from ischemia and reperfusion injury.

  14. A Reconstruction Method of Blood Flow Velocity in Left Ventricle Using Color Flow Ultrasound.

    Science.gov (United States)

    Jang, Jaeseong; Ahn, Chi Young; Jeon, Kiwan; Heo, Jung; Lee, DongHak; Joo, Chulmin; Choi, Jung-il; Seo, Jin Keun

    2015-01-01

    Vortex flow imaging is a relatively new medical imaging method for the dynamic visualization of intracardiac blood flow, a potentially useful index of cardiac dysfunction. A reconstruction method is proposed here to quantify the distribution of blood flow velocity fields inside the left ventricle from color flow images compiled from ultrasound measurements. In this paper, a 2D incompressible Navier-Stokes equation with a mass source term is proposed to utilize the measurable color flow ultrasound data in a plane along with the moving boundary condition. The proposed model reflects out-of-plane blood flows on the imaging plane through the mass source term. The boundary conditions to solve the system of equations are derived from the dimensions of the ventricle extracted from 2D echocardiography data. The performance of the proposed method is evaluated numerically using synthetic flow data acquired from simulating left ventricle flows. The numerical simulations show the feasibility and potential usefulness of the proposed method of reconstructing the intracardiac flow fields. Of particular note is the finding that the mass source term in the proposed model improves the reconstruction performance. PMID:26078773

  15. Regional cerebral blood flow in stroke by 133Xenon inhalation and emission tomography

    DEFF Research Database (Denmark)

    Lassen, N A; Henriksen, L; Paulson, O

    1981-01-01

    A rapidly rotating single-photon emission tomograph was used to study regional cerebral blood flow by 133Xenon inhalation. Using a rotation speed of 180 degrees/5 sec a tomographic picture of the average Xenon concentration in 3 slices is obtained. By taking a sequence of 4 one-minute tomograms d...... cerebral blood flow measured tomographically by 133Xenon inhalation circumvents the extra-cranial contamination and the superposition of intracranial tissues that hamper 133Xenon inhalation flow studies using stationary detectors.......A rapidly rotating single-photon emission tomograph was used to study regional cerebral blood flow by 133Xenon inhalation. Using a rotation speed of 180 degrees/5 sec a tomographic picture of the average Xenon concentration in 3 slices is obtained. By taking a sequence of 4 one-minute tomograms...... during and after a one-minute 133Xenon inhalation period a flow-dependent variation in local isotope concentration is seen. This sequence is used for calculating CBF by a deconvolution procedure. The CBF maps have a spatial resolution of approximately 1.7 cm (FWHM). This preliminary study comprises...

  16. Numerical simulation of blood flow and interstitial fluid pressure in solid tumor microcirculation based on tumor-induced angiogenesis

    Institute of Scientific and Technical Information of China (English)

    Gaiping Zhao; Jie Wu; Shixiong Xu; M. W. Collins; Quan Long; Carola S. K(o)nig; Yuping Jiang; Jian Wang; A. R. Padhani

    2007-01-01

    A coupled intravascular-transvascular-interstitial fluid flow model is developed to study the distributions of blood flow and interstitial fluid pressure in solid tumor microcirculation based on a tumor-induced microvascular network.This is generated from a 2D nine-point discrete mathematical model of tumor angiogenesis and contains two parent vessels.Blood flow through the microvascular network and interstitial fluid flow in tumor tissues are performed by the extended Poiseuille's law and Darcy's law, respectively, transvascular flow is described by Starling's law; effects of the vascular permeability and the interstitial hydraulic conductivity are also considered. The simulation results predict the heterogeneous blood supply, interstitial hypertension and low convectionon the inside of the tumor, which are consistent with physiological observed facts. These results may provide beneficial information for anti-angiogenesis treatment of tumor and further clinical research.

  17. Numerical simulation of blood flow and interstitial fluid pressure in solid tumor microcirculation based on tumor-induced angiogenesis

    Science.gov (United States)

    Zhao, Gaiping; Wu, Jie; Xu, Shixiong; Collins, M. W.; Long, Quan; König, Carola S.; Jiang, Yuping; Wang, Jian; Padhani, A. R.

    2007-10-01

    A coupled intravascular transvascular interstitial fluid flow model is developed to study the distributions of blood flow and interstitial fluid pressure in solid tumor microcirculation based on a tumor-induced microvascular network. This is generated from a 2D nine-point discrete mathematical model of tumor angiogenesis and contains two parent vessels. Blood flow through the microvascular network and interstitial fluid flow in tumor tissues are performed by the extended Poiseuille’s law and Darcy’s law, respectively, transvascular flow is described by Starling’s law; effects of the vascular permeability and the interstitial hydraulic conductivity are also considered. The simulation results predict the heterogeneous blood supply, interstitial hypertension and low convection on the inside of the tumor, which are consistent with physiological observed facts. These results may provide beneficial information for anti-angiogenesis treatment of tumor and further clinical research.

  18. Quantification of complex blood flow using real-time in vivo vector flow ultrasound

    DEFF Research Database (Denmark)

    Pedersen, Mads Møller; Pihl, Michael Johannes; Haugaard, Per;

    2010-01-01

    A quantitative method for distinguishing complex from non-complex flow patterns in ultrasound is presented. A new commercial BK Medical ultrasound scanner uses the Transverse Oscillation vector flow technique for visualising flow patterns in real-time. In vivo vector flow data of the blood flow...... ultrasound. From the same data the mean standard deviation of the flow angles (MSTDA) were calculated and compared to the expert evaluations. Comparison between the combined experts evaluations and the MSTDA was performed. Using linear regression analysis, a correlation coefficient of 0.925 was found....... The upper and lower bounds for a 95% confidence interval of 0.974 and 0.792 respectively, were calculated. The MSTDA was below 25 for the common carotid artery and above 25 for the carotid bulb. Thus, the MSTDA value can distinguishing complex flow from non-complex flow and can be used as the basis...

  19. Altering blood flow does not reveal differences between nitrogen and helium kinetics in brain or in skeletal miracle in sheep.

    Science.gov (United States)

    Doolette, David J; Upton, Richard N; Grant, Cliff

    2015-03-01

    In underwater diving, decompression schedules are based on compartmental models of nitrogen and helium tissue kinetics. However, these models are not based on direct measurements of nitrogen and helium kinetics. In isoflurane-anesthetized sheep, nitrogen and helium kinetics in the hind limb (n = 5) and brain (n = 5) were determined during helium-oxygen breathing and after return to nitrogen-oxygen breathing. Nitrogen and helium concentrations in arterial, femoral vein, and sagittal sinus blood samples were determined using headspace gas chromatography, and venous blood flows were monitored continuously using ultrasonic Doppler. The experiment was repeated at different states of hind limb blood flow and cerebral blood flow. Using arterial blood gas concentrations and blood flows as input, parameters and model selection criteria of various compartmental models of hind limb and brain were estimated by fitting to the observed venous gas concentrations. In both the hind limb and brain, nitrogen and helium kinetics were best fit by models with multiexponential kinetics. In the brain, there were no differences in nitrogen and helium kinetics. Hind limb models fit separately to the two gases indicated that nitrogen kinetics were slightly faster than helium, but models with the same kinetics for both gases fit the data well. In the hind limb and brain, the blood:tissue exchange of nitrogen is similar to that of helium. On the basis of these results, it is inappropriate to assign substantially different time constants for nitrogen and helium in all compartments in decompression algorithms. PMID:25525213

  20. Oxidative Damage to Lung Tissue and Peripheral Blood in Endotracheal PM2.5-treated Rats

    Institute of Scientific and Technical Information of China (English)

    ZHI-QING LIN; ZHU-GE XI; DAN-FENG YANG; FU-HUAN CHAO; HUA-SHAN ZHANG; WEI ZHANG; HUANG-LIANG LIU; ZAI-MING YANG; RU-BAO SUN

    2009-01-01

    Objective To investigate the oxidative damage to lung tissue and peripherial blood in PM2.5-treated rats.Methods PM2.5 samples were collected using an auto-sampling instrument in summer and winter.Treated samples were endotracheally instilled into rats.Activity of reduced glutathione peroxidase (GSH-Px) and concentration of malondialdehyde (MDA) were used as oxidative damage biomarkers of lung tissue and peripheral blood detected with the biochemical method.DNA migration length (μm) and rate of tail were used as DNA damage biomarkers of lung tissue and peripheral blood detected with the biochemical method. Results The activity of GSH-Px and the concentration of MDA in lung tissue significantly decreased after exposure to PM2.5 for 7-14 days.In peripheral blood,the concentration of MDA decreased,but the activity of GSH-Px increased 7 and 14 days after experiments.The two indicators had a dose-effect relation and similar changing tendency in lung tissue and peripheral blood.The DNA migration length (μm) and rate of tail in lung tissue and peripheral blood significantly increased 7 and 14 days after exposure to PM2.5.The two indicators had a dose-effect relation and similar changing tendency in lung tissue and peripheral blood. Conclusion PM2.5 has a definite oxidative effect on lung tissue and peripheral blood.The activity of GSH-Px and the concentration of MDA are valuable biomarkers of oxidative lung tissue damage induced by PM2.5.The DNA migration length (μm) and rate of tail are simple and valuable biomarkers of PM2.5-induced DNA damage in lung tissues and peripheral blood.The degree of DNA damage in peripheral blood can predict the degree of DNA damage in lung tissue.

  1. Case with stenosis of internal carotid artery detected as a region of decreased blood flow by Tc-99m HMPAO cerebral blood flow scintigraphy

    Energy Technology Data Exchange (ETDEWEB)

    Hayashida, K.; Nishimura, T.; Uehara, T.; Imakita, S.; Yokota, I.; Ogura, H.; Oka, H.; Hayashi, M.; Kikuchi, H.

    1987-04-01

    Tc-99m hexamethylpropyleneamine oxime (= HMPAO) is expected to be an excellent agent as blood flow tracer of brain because it passes through blood brain barrier and is retained in brain parenchyma for several hours. Tc-99m HMPAO scintigraphy was applied to a patient complaining of transient ischemic attack without neurological findings. Left hemispheric hypoperfusion was detected by Tc-99m HMPAO cerebral blood flow scintigraphy. Although it was normal in CT and MRI, it was proved to be a 99 % stenosis of left internal carotid artery by digital subtraction angiography. Tc-99m HMPAO cerebral blood flow scintigraphy is useful for detecting abnormality of cerebral blood flow.

  2. Kinetics of CLL cells in tissues and blood during therapy with the BTK inhibitor ibrutinib

    OpenAIRE

    Wodarz, Dominik; Garg, Naveen; Komarova, Natalia L.; Benjamini, Ohad; Keating, Michael J.; Wierda, William G.; Kantarjian, Hagop; James, Danelle; O’Brien, Susan; Burger, Jan A.

    2014-01-01

    During ibrutinib therapy, 1.7% of blood and 2.7% of tissue CLL cells die per day which is 3 and 5 times higher than without treatment.The fraction of CLL cells that redistribute into the blood during ibrutinib treatment represents 23.3% ± 17% of the tissue disease burden.

  3. Methods for measurement of cerebral blood flow in man

    DEFF Research Database (Denmark)

    Lassen, N A

    1976-01-01

    A survey of the currently available methods for the measurement of cerebral blood flow in man is given. Many of the clinically important brain diseases such as tumors, stroke, brain trauma or epilepsy entail focal or regional flow alterations. Therefore a special emphasis is placed on methods...... information both on spatial localization and, especially, on ischemic areas. The most promising is computer-assisted axial tomography with freely diffusible radioactive isotopes or with x-rays using an intra-arterial injection of contrast. But, the available techniques are still too slow: in order to measure...

  4. Occlusion cuff for routine measurement of digital blood pressure and blood flow

    DEFF Research Database (Denmark)

    Lassen, N A; Krähenbühl, B; Hirai, M

    1977-01-01

    A miniaturized blood pressure cuff made of plastic material and applicable to fingers and toes is described. The cuff was compared to rubber cuffs and to bladder-free cuffs. It was found to be more reliable than the former type and much easier to use than the latter type. It is recommended for us...... in conjunction with a mercury-in-Silastic strain gauge for routine measurement of digital blood pressure and blood flow in patients with arterial disease.......A miniaturized blood pressure cuff made of plastic material and applicable to fingers and toes is described. The cuff was compared to rubber cuffs and to bladder-free cuffs. It was found to be more reliable than the former type and much easier to use than the latter type. It is recommended for use...

  5. Cafeteria diet induce changes in blood flow that are more related with heat dissipation than energy accretion

    Science.gov (United States)

    Sabater, David; Agnelli, Silvia; Arriarán, Sofía; Romero, María del Mar; Fernández-López, José Antonio; Alemany, Marià

    2016-01-01

    Background. A “cafeteria” diet is a self-selected high-fat diet, providing an excess of energy, which can induce obesity. Excess of lipids in the diet hampers glucose utilization eliciting insulin resistance, which, further limits amino acid oxidation for energy. Methods. Male Wistar rats were exposed for a month to “cafeteria” diet. Rats were cannulated and fluorescent microspheres were used to determine blood flow. Results. Exposure to the cafeteria diet did not change cardiac output, but there was a marked shift in organ irrigation. Skin blood flow decreased to compensate increases in lungs and heart. Blood flow through adipose tissue tended to increase in relation to controls, but was considerably increased in brown adipose tissue (on a weight basis). Discussion. The results suggest that the cafeteria diet-induced changes were related to heat transfer and disposal. PMID:27547590

  6. Cafeteria diet induce changes in blood flow that are more related with heat dissipation than energy accretion.

    Science.gov (United States)

    Sabater, David; Agnelli, Silvia; Arriarán, Sofía; Romero, María Del Mar; Fernández-López, José Antonio; Alemany, Marià; Remesar, Xavier

    2016-01-01

    Background. A "cafeteria" diet is a self-selected high-fat diet, providing an excess of energy, which can induce obesity. Excess of lipids in the diet hampers glucose utilization eliciting insulin resistance, which, further limits amino acid oxidation for energy. Methods. Male Wistar rats were exposed for a month to "cafeteria" diet. Rats were cannulated and fluorescent microspheres were used to determine blood flow. Results. Exposure to the cafeteria diet did not change cardiac output, but there was a marked shift in organ irrigation. Skin blood flow decreased to compensate increases in lungs and heart. Blood flow through adipose tissue tended to increase in relation to controls, but was considerably increased in brown adipose tissue (on a weight basis). Discussion. The results suggest that the cafeteria diet-induced changes were related to heat transfer and disposal. PMID:27547590

  7. Subcutaneous blood flow in early male pattern baldness

    International Nuclear Information System (INIS)

    The subcutaneous blood flow (SBF) was measured by the 133Xe washout method in the scalp of 14 patients with early male pattern baldness. Control experiments were performed in 14 normal haired men matched for age. The SBF in the scalp of the normal individuals was about 10 times higher than previously reported SBF values in other anatomical regions. In patients with early male pattern baldness, SBF was 2.6 times lower than the values found in the normal individuals (13.7 +/- 9.6 vs 35.7 +/- 10.5 ml/100 g/min-1). This difference was statistically significant (p much less than 0.001). A reduced nutritive blood flow to the hair follicles might be a significant event in the pathogenesis of early male pattern baldness

  8. Clitoral blood flow increases following vaginal pressure stimulation.

    Science.gov (United States)

    Lavoisier, P; Aloui, R; Schmidt, M H; Watrelot, A

    1995-02-01

    The vascular responses of clitoral arteries to vaginal pressure stimulation in 10 volunteer women were evaluated by Doppler ultrasonography. Pressure stimulations (20-160 mm Hg) along the lower third of the vagina increased blood velocity and flow into clitoral arteries in 9 of the 10 women. The latency and duration of the Doppler responses ranged from 0.1 to 1.6 sec and from 3.2 to 9.5 sec, respectively, and the response was associated with a blood flow increase of 4 to 11 times the baseline prestimulation level. This response parallels that recorded in the cavernous arteries in men when a similar range of pressure stimulations are applied to the glans penis. Similar responses evoked in the male and female suggest a sexual synergy that may occur during intercourse in that such physiological responses and reflexes may be reciprocally reinforced.

  9. Pressure Gradient Estimation Based on Ultrasonic Blood Flow Measurement

    Science.gov (United States)

    Nitta, Naotaka; Homma, Kazuhiro; Shiina, Tsuyoshi

    2006-05-01

    Mechanical load to the blood vessel wall, such as shear stress and pressure, which occurs in blood flow dynamics, contribute greatly to plaque rupture in arteriosclerosis and to biochemical activation of endothelial cells. Therefore, noninvasive estimations of these mechanical loads are able to provide useful information for the prevention of vascular diseases. Although the pressure is the dominant component of mechanical load, for practical purposes, the pressure gradient is also often important. So far, we have investigated the estimation of the kinematic viscosity coefficient using a combination of the Navier-Stokes equations and ultrasonic velocity measurement. In this paper, a method for pressure gradient estimation using the estimated kinematic viscosity coefficient is proposed. The validity of the proposed method was investigated on the basis of the analysis with the data obtained by computer simulation and a flow phantom experiment. These results revealed that the proposed method can provide a valid estimation of the pressure gradient.

  10. Subcutaneous blood flow in early male pattern baldness

    Energy Technology Data Exchange (ETDEWEB)

    Klemp, P.; Peters, K.; Hansted, B.

    1989-05-01

    The subcutaneous blood flow (SBF) was measured by the /sup 133/Xe washout method in the scalp of 14 patients with early male pattern baldness. Control experiments were performed in 14 normal haired men matched for age. The SBF in the scalp of the normal individuals was about 10 times higher than previously reported SBF values in other anatomical regions. In patients with early male pattern baldness, SBF was 2.6 times lower than the values found in the normal individuals (13.7 +/- 9.6 vs 35.7 +/- 10.5 ml/100 g/min-1). This difference was statistically significant (p much less than 0.001). A reduced nutritive blood flow to the hair follicles might be a significant event in the pathogenesis of early male pattern baldness.

  11. Cerebral autoregulation control of blood flow in the brain

    CERN Document Server

    Payne, Stephen

    2016-01-01

    This Brief provides a comprehensive introduction to the control of blood flow in the brain. Beginning with the basic physiology of autoregulation, the author goes on to discuss measurement techniques, mathematical models, methods of analysis, and relevant clinical conditions, all within this single volume. The author draws together this disparate field, and lays the groundwork for future research directions. The text gives an up-to-date review of the state of the art in cerebral autoregulation, which is particularly relevant as cerebral autoregulation moves from the laboratory to the bedside. Cerebral Autoregulation will be useful to researchers in the physical sciences such as mathematical biology, medical physics, and biomedical engineering whose work is concerned with the brain. Researchers in the medical sciences and clinicians dealing with the brain and blood flow, as well as industry professionals developing techniques such as ultrasound, MRI, and CT will also find this Brief of interest.

  12. Regulation of the skeletal muscle blood flow in humans

    DEFF Research Database (Denmark)

    Mortensen, Stefan; Saltin, Bengt

    2014-01-01

    In humans, skeletal muscle blood flow is regulated by an interaction between several locally formed vasodilators including nitric oxide (NO) and prostaglandins. In plasma, ATP is a potent vasodilator that stimulates the formation of NO and prostaglandins and very importantly can offset local...... sympathetic vasoconstriction. ATP is released into plasma from erythrocytes and endothelial cells and the plasma concentration increases in both the feeding artery and the vein draining the contracting skeletal muscle. Adenosine also stimulates the formation of NO and prostaglandins, but the plasma adenosine...... concentration does not increase during exercise. In the skeletal muscle interstitium, there is a marked increase in the concentration of ATP and adenosine and this increase is tightly coupled to the increase in blood flow. The sources of interstitial ATP and adenosine are thought to be skeletal muscle cells...

  13. Pulmonary blood flow distribution measured by radionuclide computed tomography

    International Nuclear Information System (INIS)

    Distributions of pulmonary blood flow per unit lung volume were measured in sitting patients with a radionuclide computed tomography (RCT) by intravenously administered Tc-99m macroaggregates of human serum albumin (MAA). Four different types of distribution were distinguished, among which a group referred as type 2 had a three zonal blood flow distribution as previously reported (West and co-workers, 1964). The pulmonary arterial pressure (Pa) and the venous pressure (Pv) were determined in this group of distribution. These values showed satifactory agreements with the pulmonary artery pressure (Par) and the capillary wedged pressure (Pcw) measured by Swan-Ganz catheter in eighteen supine patients. Those good correlations enable to establish a noninvasive methodology for measurement of pulmonary vascular pressures

  14. In Vivo μPIV Measurements of Blood Flow in Small Vessels of a Rat Model.

    Science.gov (United States)

    Wei, Timothy; Conner, Nadine; Russell, John; Legac, Paul

    2007-11-01

    Ongoing research at the University of Wisconsin Medical School is addressing the effects of perfusion of glottal tissue on voice production. Building on the approach developed by Gharib's group at CalTech for embryonic zebra fish, we have modified μPIV to measure flow in capillaries and small blood vessels in a live rat model. In lieu of seeding particles, the DPIV correlation algorithm tracks the motion of red blood cells moving through these vessels. The methodology will be presented along with a video sequence showing measurements made from muscle tissue laid nominally flat on a microscope stage. Challenges of measurements in three-dimensional geometries, i.e. the throat, will be discussed.

  15. Relations of blood pressure and head injury to regional cerebral blood flow.

    Science.gov (United States)

    Kisser, Jason E; Allen, Allyssa J; Katzel, Leslie I; Wendell, Carrington R; Siegel, Eliot L; Lefkowitz, David; Waldstein, Shari R

    2016-06-15

    Hypertension confers increased risk for cognitive decline, dementia, and cerebrovascular disease. These associations have been attributed, in part, to cerebral hypoperfusion. Here we posit that relations of higher blood pressure to lower levels of cerebral perfusion may be potentiated by a prior head injury. Participants were 87 community-dwelling older adults - 69% men, 90% white, mean age=66.9years, 27.6% with a history of mild traumatic brain injury (mTBI) defined as a loss of consciousness ≤30min resulting from an injury to the head, and free of major medical (other than hypertension), neurological or psychiatric comorbidities. All engaged in clinical assessment of systolic and diastolic blood pressure (SBP, DBP) and single photon emission computed tomography (SPECT). Computerized coding of the SPECT images yielded relative ratios of blood flow in left and right cortical and select subcortical regions. Cerebellum served as the denominator. Sex-stratified multiple regression analyses, adjusted for age, education, race, alcohol consumption, smoking status, and depressive symptomatology, revealed significant interactions of blood pressure and head injury to cerebral blood flow in men only. Specifically, among men with a history of head injury, higher systolic blood pressure was associated with lower levels of perfusion in the left orbital (β=-3.21, p=0.024) and left dorsolateral (β=-2.61, p=0.042) prefrontal cortex, and left temporal cortex (β=-3.36, p=0.014); higher diastolic blood pressure was marginally associated with lower levels of perfusion in the left dorsolateral prefrontal cortex (β=-2.79, p=0.051). Results indicate that men with a history of head injury may be particularly vulnerable to the impact of higher blood pressure on cerebral perfusion in left anterior cortical regions, thus potentially enhancing risk for adverse brain and neurocognitive outcomes. PMID:27206865

  16. Myocardial blood flow and metabolism in left ventricular ischemic dysfunction

    OpenAIRE

    Vanoverschelde, Jean-Louis

    1995-01-01

    Due to its inherent truly quantitative capabilities, its noninvasive nature and its nondestructive characteristics, PET has emerged as a unique investigative tool for the assessment and quantification of myocardial blood flow and metabolism in man. The present thesis reviews some of the insights gained with the use of PET into the pathophysiology of regional left ventricular ischemic dysfunction. Chapters 1 and 2 dealt with definitions and specific issues pertinent to the pathophysiologic...

  17. Estimation of cerebral blood flow during cardiopulmonary resuscitation in humans

    DEFF Research Database (Denmark)

    Christensen, S F; Stadeager, Carsten Preben; Siemkowicz, E

    1990-01-01

    Cerebral blood flow (CBF) and cardiac output (CO) were measured during cardiopulmonary resuscitation in patients who were unsuccessfully resuscitated by use of C14-iodoantipyrine injected into the left ventricle. CO varied between 1.3 and 2.2 l/min with mean 1.8 +/- 0.6 l/min (+/- SD) (28 ml...... resuscitation showed signs of maldistribution suggestive of a patchy and incomplete perfusion....

  18. Feasibility of patient specific aortic blood flow CFD simulation.

    Science.gov (United States)

    Svensson, Johan; Gårdhagen, Roland; Heiberg, Einar; Ebbers, Tino; Loyd, Dan; Länne, Toste; Karlsson, Matts

    2006-01-01

    Patient specific modelling of the blood flow through the human aorta is performed using computational fluid dynamics (CFD) and magnetic resonance imaging (MRI). Velocity patterns are compared between computer simulations and measurements. The workflow includes several steps: MRI measurement to obtain both geometry and velocity, an automatic levelset segmentation followed by meshing of the geometrical model and CFD setup to perform the simulations follwed by the actual simulations. The computational results agree well with the measured data. PMID:17354898

  19. Determination of cerebral blood flow with the EMI CT scanner

    International Nuclear Information System (INIS)

    Cerebral blood flow (CBF) determinations were made in seven baboons and two patients with the EMI CT dedicated head scanner. The method for determining the CBF was tested and measurements were made during physiological states elicited by changes in pCO2 and depth of anaesthesia. The method has a number of advantages, particularly for assessing CBF responses to pCO2 changes. (author)

  20. Flow of red blood cells in capillary networks

    OpenAIRE

    Couto, Ana; Teixeira, Lúcia; Leble, Vladimir; Lima, R.; Ribeiro, António E.; Dias, Ricardo

    2011-01-01

    In the present work we have studied the flow of red blood cells through a column packed with soda lime glass spheres with diameter of 337.5 micron (pore diameter 150 micron). The ratio between the average velocity of the RBCs and the average velocity of the carrying fluid (physiological saline) was close to 0.9. The RBCs migrated faster through the column than the carrying fluid mainly due to a hydrodynamic chromatographic effect.

  1. CEREBRAL BLOOD FLOW AND METABOLISM IN ANXIETY AND ANXIETY DISORDERS

    OpenAIRE

    Mathew, Roy J.

    1994-01-01

    Anxiety disorders are some of the commonest psychiatric disorders and anxiety commonly co-exists with other psychiatric conditions. Anxiety can also be a normal emotion. Thus, study of the neurobiological effects of anxiety is of considerable significance. In the normal brain, cerebral blood flow (CBF) and metabolism (CMR) serve as indices of brain function. CBF/CMR research is expected to provide new insight into alterations in brain function in anxiety disorders and other psychiatric disord...

  2. Modeling study of terminal transients of blood flow

    Science.gov (United States)

    Stiukhina, Elena S.; Postnov, Dmitry E.

    2016-04-01

    In spite of growing body of experimental and theoretical results on blood flow (BF) patterns under the continuously sustained circulation, much less is known about BF dynamics under the exceptional, but still important cases of venous or arterial occlusion used in medical probes. Since these conditions finally lead to complete or nearly complete stop of red blood cells (RBC) motion, we term it as TTBF, being the Terminal Transients of Blood Flow. An extreme case of such transients is the ultimate extinction of BF after the stopping of heart contractions, during which it is governed by gravitation, some vascular-originated propulsion mechanisms, and, possibly, by RBC aggregation. Quite little is known about this process, while reports the detectable post-mortal motion of mice RBC during at least 2 hours. In our work we present the modeling study of TTBF patterns due to gravitational forces. We present the minimalistic model configuration of vasculature in order to simulate what happens immediately after the pumping of blood has been stopped. Our main findings are concerned to reversal of arterial BF, as well as to duration and non-monotonicity of transients.

  3. Unsteady magnetohydrodynamic blood flow through irregular multi-stenosed arteries.

    Science.gov (United States)

    Mustapha, Norzieha; Amin, Norsarahaida; Chakravarty, Santabrata; Mandal, Prashanta Kumar

    2009-10-01

    Flow of an electrically conducting fluid characterizing blood through the arteries having irregular shaped multi-stenoses in the environment of a uniform transverse magnetic-field is analysed. The flow is considered to be axisymmetric with an outline of the irregular stenoses obtained from a three-dimensional casting of a mild stenosed artery, so that the physical problem becomes more realistic from the physiological point of view. The marker and cell (MAC) and successive-over-relaxation (SOR) methods are respectively used to solve the governing unsteady magnetohydrodynamic (MHD) equations and pressure-Poisson equation quantitatively and to observe the flow separation. The results obtained show that the flow separates mostly towards the downstream of the multi-stenoses. However, the flow separation region keeps on shrinking with the increasing intensity of the magnetic-field which completely disappears with sufficiently large value of the Hartmann number. The present observations certainly have some clinical implications relating to magnetotherapy which help reducing the complex flow separation zones causing flow disorder leading to the formation and progression of the arterial diseases.

  4. Unsteady magnetohydrodynamic blood flow through irregular multi-stenosed arteries.

    Science.gov (United States)

    Mustapha, Norzieha; Amin, Norsarahaida; Chakravarty, Santabrata; Mandal, Prashanta Kumar

    2009-10-01

    Flow of an electrically conducting fluid characterizing blood through the arteries having irregular shaped multi-stenoses in the environment of a uniform transverse magnetic-field is analysed. The flow is considered to be axisymmetric with an outline of the irregular stenoses obtained from a three-dimensional casting of a mild stenosed artery, so that the physical problem becomes more realistic from the physiological point of view. The marker and cell (MAC) and successive-over-relaxation (SOR) methods are respectively used to solve the governing unsteady magnetohydrodynamic (MHD) equations and pressure-Poisson equation quantitatively and to observe the flow separation. The results obtained show that the flow separates mostly towards the downstream of the multi-stenoses. However, the flow separation region keeps on shrinking with the increasing intensity of the magnetic-field which completely disappears with sufficiently large value of the Hartmann number. The present observations certainly have some clinical implications relating to magnetotherapy which help reducing the complex flow separation zones causing flow disorder leading to the formation and progression of the arterial diseases. PMID:19665698

  5. Cerebral blood flow is reduced in patients with sepsis syndrome

    International Nuclear Information System (INIS)

    The relationship between sepsis-induced CNS dysfunction and changes in brain blood flow remains unknown, and animal studies examining the influence of sepsis on cerebral blood flow (CBF) do not satisfactorily address that relationship. We measured CBF and cerebrovascular reactivity to CO2 in nine patients with sepsis syndrome using the 133Xe clearance technique. Mean CBF was 29.6 +/- 15.8 (SD) ml/100 g.min, significantly lower than the normal age-matched value in this laboratory of 44.9 +/- 6.2 ml/100 g.min (p less than .02). This depression did not correlate with changes in mean arterial pressure. Despite the reduction in CBF, the specific reactivity of the cerebral vasculature to changes in CO2 was normal, 1.3 +/- 0.9 ml/100 g.min/mm Hg. Brain blood flow is reduced in septic humans; the contribution of this reduction to the metabolic and functional changes observed in sepsis requires further study

  6. Cerebral blood flow is reduced in patients with sepsis syndrome

    Energy Technology Data Exchange (ETDEWEB)

    Bowton, D.L.; Bertels, N.H.; Prough, D.S.; Stump, D.A.

    1989-05-01

    The relationship between sepsis-induced CNS dysfunction and changes in brain blood flow remains unknown, and animal studies examining the influence of sepsis on cerebral blood flow (CBF) do not satisfactorily address that relationship. We measured CBF and cerebrovascular reactivity to CO/sub 2/ in nine patients with sepsis syndrome using the /sup 133/Xe clearance technique. Mean CBF was 29.6 +/- 15.8 (SD) ml/100 g.min, significantly lower than the normal age-matched value in this laboratory of 44.9 +/- 6.2 ml/100 g.min (p less than .02). This depression did not correlate with changes in mean arterial pressure. Despite the reduction in CBF, the specific reactivity of the cerebral vasculature to changes in CO/sub 2/ was normal, 1.3 +/- 0.9 ml/100 g.min/mm Hg. Brain blood flow is reduced in septic humans; the contribution of this reduction to the metabolic and functional changes observed in sepsis requires further study.

  7. Predicting Endometrium Receptivity with Parameters of Spiral Artery Blood Flow

    Institute of Scientific and Technical Information of China (English)

    GONG Xuehao; LI Quanshui; ZHANG Qingping; ZHU Guijin

    2005-01-01

    Summary: In order To evaluate whether the parameters of spiral artery blood flow, as measured by transvaginal color Doppler, may be used to assess endometrium receptivity prior to embryo transfer (ET), a retrospective study of 94 infertile women who had undergone ART treatments with different outcomes (pregnant or nonpregnant) was done. Subendometrial blood flow was evaluated. The resistance index (RI), systolic/diastolic ratio (S/D) and pulsatility index (PI) were significantly lower in those who achieved pregnancy as compared with those who did not: 0.62±0.04 vs 0.68±0.04 (P<0.001), 2.66±0.33 vs 3.19±0.39 (P<0.01) and 1.15±0.17 vs 1.34±0.22 (P<0.05), respectively. Furthermore, when RI>0.72, PI>1.6, and S/D>3.6, no pregnancy occurred. These data suggest that the parameters of spiral artery blood flow could be used as a new assay in predicting endometrial receptivity before ET.

  8. The Effect of Pulsatile Versus Nonpulsatile Blood Flow on Viscoelasticity and Red Blood Cell Aggregation in Extracorporeal Circulation

    OpenAIRE

    Ahn, Chi Bum; Kang, Yang Jun; Kim, Myoung Gon; Yang, Sung; Lim, Choon Hak; Son, Ho Sung; Kim, Ji Sung; Lee, So Young; Son, Kuk Hui; Sun, Kyung

    2016-01-01

    Background Extracorporeal circulation (ECC) can induce alterations in blood viscoelasticity and cause red blood cell (RBC) aggregation. In this study, the authors evaluated the effects of pump flow pulsatility on blood viscoelasticity and RBC aggregation. Methods Mongrel dogs were randomly assigned to two groups: a nonpulsatile pump group (n=6) or a pulsatile pump group (n=6). After ECC was started at a pump flow rate of 80 mL/kg/min, cardiac fibrillation was induced. Blood sampling was perfo...

  9. Effects of hypothyroidism on vascular 125I-albumin permeation and blood flow in rats

    International Nuclear Information System (INIS)

    Effects of hypothyroidism on vascular 125I-albumin permeation and on blood flow were assessed in multiple tissues of male Sprague-Dawley rats rendered hypothyroid by dietary supplementation with 0.5% (wt/wt) 2-thiouracil or by thyroidectomy. In both thiouracil-treated and thyroidectomized rats, body weights, kidney weight, arterial blood pressure, and pulse rate were decreased significantly v age-matched controls. After 10 to 12 weeks of thiouracil treatment, 125I-albumin permeation was increased significantly in the kidney, aorta, eye (anterior uvea, choroid, retina), skin, and new granulation tissue, remained unchanged in brain, sciatic nerve, and heart, and was decreased in forelimb skeletal muscle. A similar pattern was observed in thyroidectomized rats, except that increases in 125I-albumin permeation for all tissues were smaller than those observed in thiouracil-treated rats, and 125I-albumin permeation in retina did not differ from controls. In both thiouracil-treated and thyroidectomized rats, changes in blood flow (assessed with 15-microns, 85Sr-labeled microspheres) relative to the decrease in arterial blood pressure were indicative of a decrease in regional vascular resistance except in the choroid and in the kidney, in which vascular resistance was increased significantly. Glomerular filtration rate was decreased, but filtration fraction and urinary excretion of albumin remained unchanged by thiouracil treatment and thyroidectomy. These results indicate that vascular hemodynamics and endothelial cell barrier functional integrity are modulated in many different tissues by the thyroid. In view of the correspondence of hypothyroid- and diabetes-induced vascular permeability changes, these results raise the possibility that altered thyroid function in diabetes may play a role in the pathogenesis of diabetic vascular disease

  10. Nocturnal variations in lower-leg subcutaneous blood flow in paraplegic men

    DEFF Research Database (Denmark)

    Sindrup, J H; Wroblewski, H; Kastrup, J;

    1992-01-01

    1. Lower-leg subcutaneous adipose tissue blood flow rates were measured over 12-20 h under ambulatory conditions by means of the 133Xe-washout technique in nine paraplegic men, all with complete spinal cord lesions at or below the Th 6 level, and in nine age-matched healthy men. Portable Cd......Te(Cl) detectors and data-storage units were used. 2. The central and local sympathetic vasoconstrictive activity at the lower leg was measured under laboratory conditions by means of the 133Xe-washout technique and a stationary NaI(Tl) detector system. 3. The paraplegic men were found to have intact central...... and local sympathetic vasoconstrictive activity in their lower legs. Moreover, they all had a nocturnal hyperaemic blood flow phase of the same magnitude and duration as the control subjects. 4. The possibility that the somaesthetic nerves play a role in the hyperaemic response could be excluded, as all...

  11. Human Blood-Vessel-Derived Stem Cells for Tissue Repair and Regeneration

    OpenAIRE

    Chien-Wen Chen; Mirko Corselli; Bruno Péault; Johnny Huard

    2012-01-01

    Multipotent stem/progenitor cells with similar developmental potentials have been independently identified from diverse human tissue/organ cultures. The increasing recognition of the vascular/perivascular origin of mesenchymal precursors suggested blood vessels being a systemic source of adult stem/progenitor cells. Our group and other laboratories recently isolated multiple stem/progenitor cell subsets from blood vessels of adult human tissues. Each of the three structural layers of blood ve...

  12. Sodium hydrosulfide alleviated pulmonary vascular structural remodeling induced by high pulmonary blood flow in rats

    Institute of Scientific and Technical Information of China (English)

    Xiao-hui LI; Jun-bao DU; Ding-fang BU; Xiu-ying TANG; Chao-shu TANG

    2006-01-01

    Aim: To explore the possible role of endogenous hydrogen sulfide (H2S), a novel gasotransmitter, in the pathogenesis of pulmonary vascular structural remodeling (PVSR) induced by high pulmonary blood flow. Methods: Thirty-two Sprague-Dawley male rats were randomly divided into sham, shunt, sham+NaHS (a H2S donor) and shunt+NaHS groups. Rats in shunt and shunt+NaHS groups underwent an abdominal aorta-inferior vena cava shunt, and rats in shunt+NaHS and sham+NaHS groups were intraperitoneally injected with NaHS. PVSR was investigated using optical microscope and transmission electron microscope. Lung tissue H2S was evaluated by sulfide-sensitive electrodes. Nitric oxide synthase (NOS), heme oxygenase (HO-1), proliferative cell nuclear antigen (PCNA) and extracellular signal-regulated kinase (ERK) activation were analyzed by Western blotting. Results: After 11 weeks of shunting, PVSR developed with a decrease in lung tissue H2S production and an increase in nitric oxide (NO). However, lung tissue carbon monoxide (CO) did not change. After the treatment with NaHS for 11 weeks, H2S donor ameliorated PVSR and downregulated PCNA expression and ERK activation with an increase in lung tissue CO production and HO-1 protein expression but a decrease in NO production, NOS activity and eNOS protein expression in shunted rats. Conclusions: H2S exerted a regulatory effect on PVSR induced by high pulmonary blood flow. Meanwhile, H2S down-regulated the ERK/MAPK signal pathway, inhibited the NO/NOS pathway and enhanced the CO/HO pathway in rats with high pulmonary blood flow.

  13. Measurement of regional cerebral blood flow by intravenous administation of 133 xenon

    International Nuclear Information System (INIS)

    Reviewing the background and the theory for rCFB measurements the following conditions are established for the use of flow measurement with 133-Xenon as a reliable indicator for indirect measurements of cerebral functional activity. 1. There is a strict coupling between rCBF and regional metabolism. This condition can only be considered to be fulfilled in the normal non-anoxic bran tissue. 2. There is a close correlation between the tissue and the venous concentration of 133-Xenin which can be reliably approximated by the blood-brain partition coefficient. This condition can be considered to be fullfilled in the normal flow range, but not in pathological conditions such as cerebrovascular occlusions. 3. Intercompartment diffusion of 133-Xenon has no significant effect upon the measurement of rCBF values. This condition appear to share its limitations for fulfilement with condition 2. 4. There is no significant contamination by the extracerebral flow components at IH or IV rCBF measurements. 5. There is a negligible 'look through' effect from surrounding areas to region with focal high or low blood flow. (U.W.)

  14. Three-dimensional flow contrast imaging of deep tissue using noncontact diffuse correlation tomography

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Yu; Huang, Chong; Irwin, Daniel; He, Lian; Shang, Yu; Yu, Guoqiang, E-mail: guoqiang.yu@uky.edu [Department of Biomedical Engineering, University of Kentucky, Lexington, Kentucky 40506 (United States)

    2014-03-24

    This study extended our recently developed noncontact diffuse correlation spectroscopy flowmetry system into noncontact diffuse correlation tomography (ncDCT) for three-dimensional (3-D) flow imaging of deep tissue. A linear array of 15 photodetectors and two laser sources connected to a mobile lens-focusing system enabled automatic and noncontact scanning of flow in a region of interest. These boundary measurements were combined with a finite element framework for DCT image reconstruction implemented into an existing software package. This technique was tested in computer simulations and using a tissue-like phantom with anomaly flow contrast design. The cylindrical tube-shaped anomaly was clearly reconstructed in both simulation and phantom. Recovered and assigned flow contrast changes in anomaly were found to be highly correlated: regression slope = 1.00, R{sup 2} = 1.00, and p < 10{sup −5} in simulation and regression slope ≥ 0.97, R{sup 2} ≥ 0.96, and p < 10{sup −3} in phantom. These results exhibit promise of our ncDCT technique for 3-D imaging of deep tissue blood flow heterogeneities.

  15. Three-dimensional flow contrast imaging of deep tissue using noncontact diffuse correlation tomography

    International Nuclear Information System (INIS)

    This study extended our recently developed noncontact diffuse correlation spectroscopy flowmetry system into noncontact diffuse correlation tomography (ncDCT) for three-dimensional (3-D) flow imaging of deep tissue. A linear array of 15 photodetectors and two laser sources connected to a mobile lens-focusing system enabled automatic and noncontact scanning of flow in a region of interest. These boundary measurements were combined with a finite element framework for DCT image reconstruction implemented into an existing software package. This technique was tested in computer simulations and using a tissue-like phantom with anomaly flow contrast design. The cylindrical tube-shaped anomaly was clearly reconstructed in both simulation and phantom. Recovered and assigned flow contrast changes in anomaly were found to be highly correlated: regression slope = 1.00, R2 = 1.00, and p −5 in simulation and regression slope ≥ 0.97, R2 ≥ 0.96, and p −3 in phantom. These results exhibit promise of our ncDCT technique for 3-D imaging of deep tissue blood flow heterogeneities

  16. Effect of TIPS placement on portal and splanchnic arterial blood flow in 4-dimensional flow MRI

    Energy Technology Data Exchange (ETDEWEB)

    Stankovic, Zoran [Northwestern University, Department of Radiology, Feinberg School of Medicine, Chicago, IL (United States); University Medical Center Freiburg, Department of Diagnostic Radiology and Medical Physics, Freiburg (Germany); Roessle, Martin; Schultheiss, Michael [University Medical Center Freiburg, Department of Gastroenterology, Freiburg (Germany); Euringer, Wulf; Langer, Mathias [University Medical Center Freiburg, Department of Diagnostic Radiology and Medical Physics, Freiburg (Germany); Salem, Riad; Barker, Alex; Carr, James; Collins, Jeremy D. [Northwestern University, Department of Radiology, Feinberg School of Medicine, Chicago, IL (United States); Markl, Michael [Northwestern University, Department of Radiology, Feinberg School of Medicine, Chicago, IL (United States); Northwestern University, Department of Biomedical Engineering, McCormick School of Engineering, Chicago, IL (United States)

    2015-09-15

    To assess changes in portal and splanchnic arterial haemodynamics in patients undergoing transjugular intrahepatic portosystemic shunt (TIPS) using four-dimensional (4D) flow MRI, a non-invasive, non-contrast imaging technique. Eleven patients undergoing TIPS implantation were enrolled. K-t GRAPPA accelerated non-contrast 4D flow MRI of the liver vasculature was applied with acceleration factor R = 5 at 3Tesla. Flow analysis included three-dimensional (3D) blood flow visualization using time-resolved 3D particle traces and semi-quantitative flow pattern grading. Quantitative evaluation entailed peak velocities and net flows throughout the arterial and portal venous (PV) systems. MRI measurements were taken within 24 h before and 4 weeks after TIPS placement. Three-dimensional flow visualization with 4D flow MRI revealed good image quality with minor limitations in PV flow. Quantitative analysis revealed a significant increase in PV flow (562 ± 373 ml/min before vs. 1831 ± 965 ml/min after TIPS), in the hepatic artery (176 ± 132 ml/min vs. 354 ± 140 ml/min) and combined flow in splenic and superior mesenteric arteries (770 ml/min vs. 1064 ml/min). Shunt-flow assessment demonstrated stenoses in two patients confirmed and treated at TIPS revision. Four-dimensional flow MRI might have the potential to give new information about the effect of TIPS placement on hepatic perfusion. It may explain some unexpected findings in clinical observation studies. (orig.)

  17. Effect of TIPS placement on portal and splanchnic arterial blood flow in 4-dimensional flow MRI

    International Nuclear Information System (INIS)

    To assess changes in portal and splanchnic arterial haemodynamics in patients undergoing transjugular intrahepatic portosystemic shunt (TIPS) using four-dimensional (4D) flow MRI, a non-invasive, non-contrast imaging technique. Eleven patients undergoing TIPS implantation were enrolled. K-t GRAPPA accelerated non-contrast 4D flow MRI of the liver vasculature was applied with acceleration factor R = 5 at 3Tesla. Flow analysis included three-dimensional (3D) blood flow visualization using time-resolved 3D particle traces and semi-quantitative flow pattern grading. Quantitative evaluation entailed peak velocities and net flows throughout the arterial and portal venous (PV) systems. MRI measurements were taken within 24 h before and 4 weeks after TIPS placement. Three-dimensional flow visualization with 4D flow MRI revealed good image quality with minor limitations in PV flow. Quantitative analysis revealed a significant increase in PV flow (562 ± 373 ml/min before vs. 1831 ± 965 ml/min after TIPS), in the hepatic artery (176 ± 132 ml/min vs. 354 ± 140 ml/min) and combined flow in splenic and superior mesenteric arteries (770 ml/min vs. 1064 ml/min). Shunt-flow assessment demonstrated stenoses in two patients confirmed and treated at TIPS revision. Four-dimensional flow MRI might have the potential to give new information about the effect of TIPS placement on hepatic perfusion. It may explain some unexpected findings in clinical observation studies. (orig.)

  18. Regional cerebral blood flow before and after vascular surgery in patients with transient ischemic attacks with 133-xenon inhalation tomography

    DEFF Research Database (Denmark)

    Vorstrup, S; Hemmingsen, Ralf; Lindewald, H;

    1982-01-01

    with no abnormality on the CT-scan. The abnormal blood flow pattern was found to be unchanged after clinically successful reconstructive vascular surgery. This suggests the presence of irreversible ischemic tissue damage without gross emollition (incomplete infarction). It is concluded, that TIAs are often harmful...

  19. Onset of small intestinal atrophy is associated with reduced intestinal blood flow in TPN-fed neonatal piglets

    DEFF Research Database (Denmark)

    Niinikoski, Harri; Stoll, Barbara; Guan, Xinfu;

    2004-01-01

    Our aim was to determine the speed of onset of total parenteral nutrition (TPN)-induced mucosal atrophy, and whether this is associated with changes in intestinal blood flow and tissue metabolism in neonatal piglets. Piglets were implanted with jugular venous and duodenal catheters and either a p...

  20. ABO blood grouping from hard and soft tissues of teeth by modified absorption-elution technique

    Directory of Open Access Journals (Sweden)

    B K Ramnarayan

    2013-01-01

    Full Text Available Background: Teeth have always been known as stable tissue that can be preserved both physically and chemically for long periods of time. Blood group substances have been known to be present in both the hard and soft tissues of the teeth. Objectives: This study aimed at detection of ABO blood group substances from soft and hard tissues of teeth and also to evaluate the reliability of teeth stored for a relatively long period as a source of blood group substances by absorption-elution technique with some modifications. Results: Blood group obtained from the teeth was compared with those obtained from the blood sample. Pulp showed a very large correlation in both fresh and long-standing teeth though it decreased slightly in the latter. Hard tissue showed a large correlation in both the groups indicating that hard tissue is quite reliable to detect blood group and that there is no much difference in the reliability in both the groups. However, combining pulp and hard tissue, correlation is moderate. Correlation of blood grouping with the age, sex, and jaw distribution was carried out. Conclusion: Blood group identification from hard and soft tissues of teeth aids in the identification of an individual.

  1. Biomarkers measured in buccal and blood leukocyte DNA as proxies for colon tissue global methylation

    OpenAIRE

    Ashbury, Janet E.; Taylor, Sherryl A; Tse, M Yat; Stephen C Pang; Louw, Jacob A; Vanner, Stephen J.; King, Will D

    2014-01-01

    There is increasing interest in clarifying the role of global DNA methylation levels in colorectal cancer (CRC) etiology. Most commonly, in epidemiologic studies, methylation is measured in DNA derived from blood leukocytes as a proxy measure of methylation changes in colon tissue. However, little is known about the correlations between global methylation levels in DNA derived from colon tissue and more accessible tissues such as blood or buccal cells. This cross-sectional study utilized DNA ...

  2. Investigating the impact of oxygen concentration and blood flow variation on photodynamic therapy

    Science.gov (United States)

    Penjweini, Rozhin; Kim, Michele M.; Finlay, Jarod C.; Zhu, Timothy C.

    2016-03-01

    Type II photodynamic therapy (PDT) is used for cancer treatment based on the combined action of a photosensitizer, a special wavelength of light, oxygen (3O2) and generation of singlet oxygen (1O2). Intra-patient and inter-patient variability of oxygen concentration ([3O2]) before and after the treatment as well as photosensitizer concentration and hemodynamic parameters such as blood flow during PDT has been reported. Simulation of these variations is valuable, as it would be a means for the rapid assessment of treatment effect. A mathematical model has been previously developed to incorporate the diffusion equation for light transport in tissue and the macroscopic kinetic equations for simulation of [3O2], photosensitizers in ground and triplet states and concentration of the reacted singlet oxygen ([1O₂]rx) during PDT. In this study, the finite-element based calculation of the macroscopic kinetic equations is done for 2-(1- Hexyloxyethyl)-2-devinyl pyropheophorbide (HPPH)-mediated PDT by incorporating the information of the photosensitizer photochemical parameters as well as the tissue optical properties, photosensitizer concentration, initial oxygen concentration ([3O2]0), blood flow changes and Φ that have been measured in mice bearing radiation-induced fibrosarcoma (RIF) tumors. Then, [1O2]rx calculated by using the measured [3O2] during the PDT is compared with [1O2]rx calculated based on the simulated [3O₂]; both calculations showed a reasonably good agreement. Moreover, the impacts of the blood flow changes and [3O2]0 on [1O2]rx have been investigated, which showed no pronounced effect of the blood flow changes on the long-term 1O2 generation. When [3O2]0 becomes limiting, small changes in [3O₂] have large effects on [1O2]rx.

  3. Resistance exercise with different volumes: blood pressure response and forearm blood flow in the hypertensive elderly

    Directory of Open Access Journals (Sweden)

    Brito AF

    2014-12-01

    Full Text Available Aline de Freitas Brito,1 Caio Victor Coutinho de Oliveira,2 Maria do Socorro Brasileiro-Santos,1 Amilton da Cruz Santos1 1Physical Education Department, 2Research Laboratory for Physical Training Applied to Performance and Health, Federal University of Paraíba, João Pessoa, Brazil Background: The purpose of this study was to evaluate the effect of two sessions of resistance exercise with different volumes on post-exercise hypotension, forearm blood flow, and forearm vascular resistance in hypertensive elderly subjects.Methods: The study was conducted with ten hypertensive elderly (65±3 years, 28.7±3 kg/m2 subjected to three experimental sessions, ie, a control session, exercise with a set (S1, and exercise with three sets (S3. For each session, the subjects were evaluated before and after intervention. In the pre-intervention period, blood pressure, forearm blood flow, and forearm vascular resistance were measured after 10 minutes of rest in the supine position. Thereafter, the subjects were taken to the gym to perform their exercise sessions or remained at rest during the same time period. Both S1 and S3 comprised a set of ten repetitions of ten exercises, with an interval of 90 seconds between exercises. Subsequently, the measurements were again performed at 10, 30, 50, 70, and 90 minutes of recovery (post-intervention in the supine position.Results: Post-exercise hypotension was greater in S3 than in S1 (systolic blood pressure, −26.5±4.2 mmHg versus −17.9±4.7 mmHg; diastolic blood pressure, −13.8±4.9 mmHg versus −7.7±5 mmHg, P<0.05. Similarly, forearm blood flow and forearm vascular resistance changed significantly in both sessions with an increase and decrease, respectively, that was more evident in S3 than in S1 (P<0.05.Conclusion: Resistance exercises with higher volume were more effective in causing post-exercise hypotension, being accompanied by an increase in forearm blood flow and a reduction of forearm vascular

  4. Renal blood flow and metabolism after cold ischaemia

    DEFF Research Database (Denmark)

    Henriksen, J H; Petersen, H K

    1984-01-01

    Peroperative measurements of renal blood flow (RBF), renal O2-uptake, and renal venous lactate/pyruvate (L/P) ratio were performed before and after a period of 30-71 min of hypothermic (10-15 degrees C) renal ischaemia in nine patients, undergoing surgery for renal calculi. Before ischaemia, RBF.......01) immediately after re-established perfusion and 36% (P less than 0.02) 30 min later. In one additional patient, who had a short warm ischaemia (8 min), the flow pattern was the same. As arterial pressure remained constant, the reduced RBF signifies an increased renal vascular resistance. Renal O2-uptake...... and renal venous L/P ratio were almost constant, indicating no significant anaerobic processes being involved in the flow response. None of the patients showed any signs of reactive hyperaemia. It is concluded that hypothermic renal ischaemia may be followed by an increased renal vascular resistance even...

  5. Low-affinity hemoglobin increases tissue PO2 and decreases arteriolar diameter and flow in the rat cremaster muscle.

    Science.gov (United States)

    Kunert, M P; Liard, J F; Abraham, D J; Lombard, J H

    1996-07-01

    The hypothesis that tissue oxygen delivery in excess of metabolic demand results in vasoconstriction and reduced blood flow was tested in the cremaster muscle of anesthetized Sprague-Dawley rats by studying the effects of an intravenous infusion of RSR-13, an allosteric effector of hemoglobin. RSR-13 reduces the affinity of hemoglobin for oxygen, causing a right shift in the oxygen dissociation curve. Thus, oxygen delivery to the tissues was increased without elevations in blood flow or blood pressure. Tissue PO2, arteriolar diameter, and RBC velocity were measured and volume flow was calculated from diameter and RBC velocity in third-order arterioles. In rats receiving RSR-13 at a rate of 200 mg kg-1 in 15 min (n = 18) P50 (the PO2 at which hemoglobin is 50% saturated) increased from 36 +/- 1 to 52 +/- 3 mm Hg, and tissue PO2 increased to a maximum of 146 +/- 12% above its control value. P50 and tissue PO2 did not change in the control group (n = 8) receiving vehicle at a rate equivalent to that in the experimental group. In a separate group of rats receiving RSR-13 (n = 7), P50 increased from 38 +/- 1 to 51 +/- 3 mm Hg, calculated arteriolar flow decreased from 9 +/- 3 to a minimum of 1.4 +/- 1 nl sec-1, and arteriolar diameter decreased from 27 +/- 3 to a minimum of 13 +/- 3 micrograms P50, volume flow, and arteriolar diameter did not change in the control group (n = 10). These results suggest that an increased tissue oxygen delivery, caused by a right shift in the oxygen dissociation curve, may cause an increase in vascular resistance independent of an elevated blood flow. PMID:8812756

  6. The effect of glucagon-like peptide-2 on arterial blood flow and cardiac parameters

    DEFF Research Database (Denmark)

    Bremholm, Lasse; Hornum, Mads; Andersen, Ulrik B;

    2010-01-01

    Glucagon-like peptide-2 (GLP-2) is known to increase mesenteric blood flow. The aim of the study was to evaluate the effect of GLP-2 on blood flow in different vascular sites, and dynamic changes in cardiac parameters.......Glucagon-like peptide-2 (GLP-2) is known to increase mesenteric blood flow. The aim of the study was to evaluate the effect of GLP-2 on blood flow in different vascular sites, and dynamic changes in cardiac parameters....

  7. An Ultrasound Simulation Model for the Pulsatile Blood Flow Modulated by the Motion of Stenosed Vessel Wall.

    Science.gov (United States)

    Zhang, Qinghui; Zhang, Yufeng; Zhou, Yi; Zhang, Kun; Zhang, Kexin; Gao, Lian

    2016-01-01

    This paper presents an ultrasound simulation model for pulsatile blood flow, modulated by the motion of a stenosed vessel wall. It aims at generating more realistic ultrasonic signals to provide an environment for evaluating ultrasound signal processing and imaging and a framework for investigating the behaviors of blood flow field modulated by wall motion. This model takes into account fluid-structure interaction, blood pulsatility, stenosis of the vessel, and arterial wall movement caused by surrounding tissue's motion. The axial and radial velocity distributions of blood and the displacement of vessel wall are calculated by solving coupled Navier-Stokes and wall equations. With these obtained values, we made several different phantoms by treating blood and the vessel wall as a group of point scatterers. Then, ultrasound echoed signals from oscillating wall and blood in the axisymmetric stenotic-carotid arteries were computed by ultrasound simulation software, Field II. The results show better consistency with corresponding theoretical values and clinical data and reflect the influence of wall movement on the flow field. It can serve as an effective tool not only for investigating the behavior of blood flow field modulated by wall motion but also for quantitative or qualitative evaluation of new ultrasound imaging technology and estimation method of blood velocity. PMID:27478840

  8. Nailfold capillaroscopy and blood flow laser-doppler analysis of the microvascular damage in systemic sclerosis: preliminary results

    Directory of Open Access Journals (Sweden)

    C. Pizzorni

    2011-06-01

    Full Text Available Objectives: Systemic sclerosis (SSc is characterized by altered microvascular structure and function. Nailfold videocapillaroscopy (NVC is the tool to evaluate capillary morphological structure and laser-Doppler Blood flowmetry (LDF can be used to estimate cutaneous blood flow of microvessels. The aim of this study was to investigate possible relationships between capillary morphology and blood flow in SSc. Methods: 27 SSc patients and 12 healthy subjects were enrolled. SSc microvascular involvement, as evaluated by NVC, was classified in three different patterns (“Early”, “Active”, “Late”. LDF analysis was performed at the II, III, IV, V hand fingers in both hands and both at cutaneous temperature and at 36°C. Statistical evaluation was carried out by non-parametric procedures. Results: Blood flow was found significantly lower in SSc patients when compared with healthy subjects (p<0.05. The heating of the probe to 36°C induced a significant increase in peripheral blood flow in all subjects compared to baseline (p <0.05, however, the amount of variation was significantly lower in patients with SSc, compared with healthy controls (p <0.05. The SSc patients with NVC “Late” pattern, showed lower values of peripheral blood flow than patients with NVC “Active” or “Early” patterns (p<0.05. Moreover, a negative correlation between the tissue perfusion score and the progression of the SSc microangiopathy was observed, as well as between the tissue perfusion and the duration of the Raynaud’s phenomenon (p <0.03. Conclusions: LDF can be employed to evaluate blood perfusion in the microvascular circulation in SSc patients. The blood flow changes observed with the LDF seem to correlate with the severity of microvascular damage in SSc as detected by NVC.

  9. Blood pressure and blood flow variation during postural change from sitting to standing: model development and validation

    DEFF Research Database (Denmark)

    Olufsen, M.S.; Ottesen, Johnny T.; Tran, H.T.;

    2005-01-01

    Short-term cardiovascular responses to postural change from sitting to standing involve complex interactions between the autonomic nervous system, which regulates blood pressure, and cerebral autoregulation, which maintains cerebral perfusion. We present a mathematical model that can predict...... dynamic changes in beat-to-beat arterial blood pressure and middle cerebral artery blood flow velocity during postural change from sitting to standing. Our cardiovascular model utilizes 11 compartments to describe blood pressure, blood flow, compliance, and resistance in the heart and systemic circulation....... To include dynamics due to the pulsatile nature of blood pressure and blood flow, resistances in the large systemic arteries are modeled using nonlinear functions of pressure. A physiologically based submodel is used to describe effects of gravity on venous blood pooling during postural change. Two types...

  10. Protection of spermatogenisis during X-irradiation and chemotherapy by temporary blood flow interruption

    International Nuclear Information System (INIS)

    In an animal model the possibility was tested to interrupt the blood flow to the testis temporarily and repeatedly. Subsequently, it was investigated whether blood flow interuption during irradiation or during cytostatic drug administration could limit the damage induced to the spermatogonial stem cells. The effect of repeatedly blood flow interruptions on spermatogenesis was evaluated. (author). 192 refs.; 15 figs.; 11 tabs

  11. Glucagon-like peptide-2 increases mesenteric blood flow in humans

    DEFF Research Database (Denmark)

    Bremholm, Lasse; Hornum, Mads; Henriksen, Birthe Merete;

    2008-01-01

    OBJECTIVE: Mesenteric blood flow is believed to be influenced by digestion and absorption of ingested macronutrients. We hypothesized that the intestinotrophic hormone, GLP-2 (glucagons-like peptide 2), may be involved in the regulation of mesenteric blood flow. Changes in mesenteric blood flow...

  12. Validation of an optical flow algorithm to measure blood flow waveforms in arteries using dynamic digital x-ray images

    Science.gov (United States)

    Rhode, Kawal; Lambrou, Tryphon; Hawkes, David J.; Hamilton, George; Seifalian, Alexander M.

    2000-06-01

    We have developed a weighted optical flow algorithm for the extraction of instantaneous blood velocity from dynamic digital x-ray images of blood vessels. We have carried out in- vitro validation of this technique. A pulsatile physiological blood flow circuit was constructed using sections of silicone tubing to simulate blood vessels with whole blood as the fluid. Instantaneous recording of flow from an electromagnetic flow meter (EMF) provided the gold standard measurement. Biplanar dynamic digital x-ray images of the blood vessel with injection of contrast medium were acquired at 25 fps using a PC frame capture card. Imaging of a Perspex calibration cube allowed 3D reconstruction of the vessel and determination of true dimensions. Blood flow waveforms were calculated off-line on a Sun workstation using the new algorithm. The correlation coefficient between instantaneous blood flow values obtained from the EMF and the x-ray method was r equals 0.871, n equals 1184, p less than 0.0001. The correlation coefficient for average blood flow was r equals 0.898, n equals 16, p less than 0.001. We have successfully demonstrated that our new algorithm can measure pulsatile blood flow in a vessel phantom. We aim to use this algorithm to measure blood flow clinically in patients undergoing vascular interventional procedures.

  13. Effects of exercise training with blood flow restriction on blood pressure in medicated hypertensive patients

    Directory of Open Access Journals (Sweden)

    Marcos Antônio Cezar

    2016-06-01

    Full Text Available Abstract The development of non-pharmacological approaches to hypertension (HA is critical for both prevention and treatment. This study examined the hemodynamic and biochemical responses of medicated hypertensive women to resistance exercise with blood flow restriction (vascular occlusion. Twenty-three women were randomly assigned to one of three groups: High intensity strength training (n = 8; low-intensity resistance exercise with occlusion (n = 8; and control (n = 7. The first two groups underwent eight weeks of training performed twice a week, including three series of wrist flexion exercises with or without vascular occlusion. The exercised with occlusion group showed pre- to post-test reduction in systolic and diastolic blood pressure, mean arterial pressure, and double product, whereas the other groups showed no significant hemodynamic changes. In conclusion, resistance exercise during 8 weeks was effective in lowering blood pressure in medicated hypertensive subjects.

  14. Blood BDNF concentrations reflect brain-tissue BDNF levels across species

    DEFF Research Database (Denmark)

    Klein, Anders B; Williamson, Rebecca; Santini, Martin A;

    2011-01-01

    Brain-derived neurotrophic factor (BDNF) is involved in synaptic plasticity, neuronal differentiation and survival of neurons. Observations of decreased serum BDNF levels in patients with neuropsychiatric disorders have highlighted the potential of BDNF as a biomarker, but so far there have been...... no studies directly comparing blood BDNF levels to brain BDNF levels in different species. We examined blood, serum, plasma and brain-tissue BDNF levels in three different mammalian species: rat, pig, and mouse, using an ELISA method. As a control, we included an analysis of blood and brain tissue from...... conditional BDNF knockout mice and their wild-type littermates. Whereas BDNF could readily be measured in rat blood, plasma and brain tissue, it was undetectable in mouse blood. In pigs, whole-blood levels of BDNF could not be measured with a commercially available ELISA kit, but pig plasma BDNF levels (mean...

  15. Development of a Flexible Implantable Sensor for Postoperative Monitoring of Blood Flow

    OpenAIRE

    Cannata, Jonathan M.; Chilipka, Thomas; Yang, Hao-Chung; Han, Sukgu; Ham, Sung W.; Rowe, Vincent L.; Weaver, Fred A; Shung, K. Kirk; Vilkomerson, David

    2012-01-01

    We have developed a blood flow measurement system using Doppler ultrasound flow sensors fabricated of thin and flexible piezoelectric-polymer films. These flow sensors can be wrapped around a blood vessel and accurately measure flow. The innovation that makes this flow sensor possible is the diffraction-grating transducer. A conventional transducer produces a sound beam perpendicular to its face; therefore, when placed on the wall of a blood vessel, the Doppler shift in the backscattered ultr...

  16. Autoregulation of cerebral blood flow in orthostatic hypotension

    Science.gov (United States)

    Novak, V.; Novak, P.; Spies, J. M.; Low, P. A.

    1998-01-01

    BACKGROUND AND PURPOSE: We sought to evaluate cerebral autoregulation in patients with orthostatic hypotension (OH). METHODS: We studied 21 patients (aged 52 to 78 years) with neurogenic OH during 80 degrees head-up tilt. Blood flow velocities (BFV) from the middle cerebral artery were continuously monitored with transcranial Doppler sonography, as were heart rate, blood pressure (BP), cardiac output, stroke volume, CO2, total peripheral resistance, and cerebrovascular resistance. RESULTS: All OH patients had lower BP (PTPR (P.75) but with a flat slope. An expansion of the "autoregulated" range was seen in some patients. The OH_AF group was characterized by a profound fall in BFV in response to a small reduction in BP (mean deltaBP .75). CONCLUSIONS: The most common patterns of cerebral response to OH are autoregulatory failure with a flat flow-pressure relationship or intact autoregulation with an expanded autoregulated range. The least common pattern is autoregulatory failure with a steep flow-pressure relationship. Patients with patterns 1 and 2 have an enhanced capacity to cope with OH, while those with pattern 3 have reduced capacity.

  17. Effects of intramedullary reaming and nailing on blood flow in rat femora

    Energy Technology Data Exchange (ETDEWEB)

    Indrekvam, K.; Lekven, J.; Engesaeter, L.B.; Langeland, N. (University of Bergen, Surgical Research Laboratory, Orthopedic Division, Haukeland Hospital, Bergen (Norway))

    1992-01-01

    The right femur in 40 rats was reamed, and in 40 others it was additionally nailed. Analysis of bone blood flow was performed by the distribution of radiolabeled microspheres at different postoperative time intervals. Blood-flow measurements were accompanied by analyses of hydroxyproline and calcium contents. Immediately after reaming, the blood flow of the diaphyseal part of the femur was reduced to approximately one third of that of the intact femur, whereas the contents of hydroxyproline and calcium were reduced by 10 percent. Within 1 week, the blood flow was normal. This study provides evidence that the presence of a nail does not interfere with the restoration of bone blood flow. Restoration of blood flow in bone apparently is a rapid process. The replacement of hydroxyproline and calcium contents seemed to be linked to flow, as no increase in these constituents were found until the blood flow had approximated the level of the intact femur. (au).

  18. Mucosal blood flow measurements using laser Doppler perfusion monitoring

    Institute of Scientific and Technical Information of China (English)

    Dag Arne Lihaug Hoff; Hans Gregersen; Jan Gunnar Hatlebakk

    2009-01-01

    Perfusion of individual tissues is a basic physiological process that is necessary to sustain oxygenation and nutrition at a cellular level. Ischemia, or the insufficiency of perfusion, is a common mechanism for tissue death or degeneration, and at a lower threshold, a mechanism for the generation of sensory signalling including pain. It is of considerable interest to study perfusion of peripheral abdominal tissues in a variety of circumstances. Microvascular disease of the abdominal organs has been implicated in the pathogenesis of a variety of disorders, including peptic ulcer disease, inflammatory bowel disease and chest pain. The basic principle of laser Doppler perfusion monitoring (LDPM) is to analyze changes in the spectrum of light reflected from tissues as a response to a beam of monochromatic laser light emitted. It reflects the total local microcirculatory blood perfusion, including perfusion in capillaries, arterioles, venules and shunts. During the last 20-25 years, numerous studies have been performed in different parts of the gastrointestinal (GI) tract using LDPM. In recent years we have developed a multi-modal catheter device which includes a laser Doppler probe, with the intent primarily to investigate patients suffering from functional chest pain of presumed oesophageal origin. Preliminary studies show the feasibility of incorporating LDPM into such catheters for performing physiological studies in the GI tract. LDPM has emerged as a research and clinical tool in preference to other methods; but, it is important to be aware of its limitations and account for them when reporting results.

  19. Developmental validation of a novel lateral flow strip test for rapid identification of human blood (Rapid Stain Identification--Blood).

    Science.gov (United States)

    Schweers, Brett A; Old, Jennifer; Boonlayangoor, P W; Reich, Karl A

    2008-06-01

    Human blood is the body fluid most commonly encountered at crime scenes, and blood detection may aid investigators in reconstructing what occurred during a crime. In addition, blood detection can help determine which items of evidence should be processed for DNA-STR testing. Unfortunately, many common substances can cause red-brown stains that resemble blood. Furthermore, many current human blood detection methods are presumptive and prone to false positive results. Here, the developmental validation of a new blood identification test, Rapid Stain Identification--Blood (RSID--Blood), is described. RSID--Blood utilizes two anti-glycophorin A (red blood cell membrane specific protein) monoclonal antibodies in a lateral flow strip test format to detect human blood. We present evidence demonstrating that this test is accurate, reproducible, easy to use, and highly specific for human blood. Importantly, RSID--Blood does not cross-react with ferret, skunk, or primate blood and exhibits no high-dose hook effect. Also, we describe studies on the sensitivity, body fluid specificity, and species specificity of RSID--Blood. In addition, we show that the test can detect blood from a variety of forensic exhibits prior to processing for DNA-STR analysis. In conclusion, we suggest that RSID--Blood is effective and useful for the detection of human blood on forensic exhibits, and offers improved blood detection when compared to other currently used methods.

  20. Testing of models of flow-induced hemolysis in blood flow through hypodermic needles.

    Science.gov (United States)

    Chen, Yangsheng; Kent, Timothy L; Sharp, M Keith

    2013-03-01

    Hemolysis caused by flow in hypodermic needles interferes with a number of tests on blood samples drawn by venipuncture, including assays for metabolites, electrolytes, and enzymes, causes discomfort during dialysis sessions, and limits transfusion flow rates. To evaluate design modifications to address this problem, as well as hemolysis issues in other cardiovascular devices, computational fluid dynamics (CFD)-based prediction of hemolysis has potential for reducing the time and expense for testing of prototypes. In this project, three CFD-integrated blood damage models were applied to flow-induced hemolysis in 16-G needles and compared with experimental results, which demonstrated that a modified needle with chamfered entrance increased hemolysis, while a rounded entrance decreased hemolysis, compared with a standard needle with sharp entrance. After CFD simulation of the steady-state velocity field, the time histories of scalar stress along a grid of streamlines were calculated. A strain-based cell membrane failure model and two empirical power-law blood damage models were used to predict hemolysis on each streamline. Total hemolysis was calculated by weighting the predicted hemolysis along each streamline by the flow rate along each streamline. The results showed that only the strain-based blood damage model correctly predicted increased hemolysis in the beveled needle and decreased hemolysis in the rounded needle, while the power-law models predicted the opposite trends. PMID:23419169

  1. The hydrogen gas clearance method for liver blood flow examination: inhalation or local application of hydrogen?

    Science.gov (United States)

    Metzger, H P

    1989-01-01

    The combined method of hydrogen inhalation and local hydrogen production enable the determination of hepatic blood flow (HBF) and local hepatic blood flow (LHBF). LHBF was registered within a small superficial tissue volume of 0.5 mm in diameter by means of a multi-wire electrode having 200 microns producing and 100 microns measuring wires arranged within less than 300 microns distance between the measuring wires. The feeding current for hydrogen production was 1 microA, the potential less than 10 V. The clearance in response to inhalation was registered by means of the same measuring electrodes within the same tissue volume. Spontaneously breathing rats (Wistar-Frömter strain, 180-230 g bw, N = 19, ketamin-xylazine anesthesia, artificial respiration) showed the following flow values: HBF +/- SD = 0.50 +/- 0.26 ml/g.min, n = 48 registrations; LHBF +/- SD = 4.66 +/- 2.13 ml/g.min, n = 43. The validity of the combined method is demonstrated in the LHBF/HBF graph which summarizes the data of hemorrhagic and control animals, m = 0.1 and yo = 0.001. The correlation coefficient of r = 0.685 shows a reasonable correlation of the combined data despite the wide scattering of the individual values.

  2. Interactive retinal blood flow analysis of the macular region.

    Science.gov (United States)

    Tian, Jing; Somfai, Gábor Márk; Campagnoli, Thalmon R; Smiddy, William E; Debuc, Delia Cabrera

    2016-03-01

    The study of retinal hemodynamics plays an important role to understand the onset and progression of diabetic retinopathy. In this work, we developed an interactive retinal analysis tool to quantitatively measure the blood flow velocity (BFV) and blood flow rate (BFR) in the macular region using the Retinal Function Imager (RFI). By employing a high definition stroboscopic fundus camera, the RFI device is able to assess retinal blood flow characteristics in vivo. However, the measurements of BFV using a user-guided vessel segmentation tool may induce significant inter-observer differences and BFR is not provided in the built-in software. In this work, we have developed an interactive tool to assess the retinal BFV and BFR in the macular region. Optical coherence tomography data was registered with the RFI image to locate the fovea accurately. The boundaries of the vessels were delineated on a motion contrast enhanced image and BFV was computed by maximizing the cross-correlation of pixel intensities in a ratio video. Furthermore, we were able to calculate the BFR in absolute values (μl/s). Experiments were conducted on 122 vessels from 5 healthy and 5 mild non-proliferative diabetic retinopathy (NPDR) subjects. The Pearson's correlation of the vessel diameter measurements between our method and manual labeling on 40 vessels was 0.984. The intraclass correlation (ICC) of BFV between our proposed method and built-in software was 0.924 and 0.830 for vessels from healthy and NPDR subjects, respectively. The coefficient of variation between repeated sessions was reduced significantly from 22.5% to 15.9% in our proposed method (p<0.001).

  3. Simplifying the xenon-enhanced CT technique for measuring cerebral blood flow

    International Nuclear Information System (INIS)

    The authors present their study to simplify the xenon-enhanced CT technique for measuring cerebral blood flow (CBF) by monitoring the end-tidal expired-air xenon concentration (CXe) with use of CT scanning. Measurement of CBF with xenon CT requires that CXe be monitored as a function of time, and with conventional methods, specialized equipment (eg, thermoconductivity meters) is employed. In the proposed technique, CXe is monitored by scanning the patient's expired air concurrent with the brain tissue. A flexible breathing tube is used to channel the expired air through the scan field to enable sampling

  4. Cerebral lactate production and blood flow in acute stroke

    DEFF Research Database (Denmark)

    Henriksen, O; Gideon, P; Sperling, B;

    1992-01-01

    Eight stroke patients were examined serially in the acute phase and 1 week and 2-4 weeks after stroke with water-suppressed proton magnetic resonance spectroscopy. The time courses of lactate level and regional cerebral blood flow were studied. A high lactate level was found in the acute phase...... that follows reperfusion. The amount of lactate present in the acute phase reflects the severity of ischemia in the affected region. The lactate level was still above normal in the subacute phase with hyperemia, suggesting lactate production through aerobic glycolysis. Thus, the lactate level in the subacute...

  5. Endoscopic retrograde cholangiopancreatography causes reduced myocardial blood flow

    DEFF Research Database (Denmark)

    Christensen, M; Hendel, H W; Rasmussen, V;

    2002-01-01

    ). PATIENTS AND METHODS: 11 patients scheduled for ERCP were monitored with a Holter tape recorder and underwent myocardial perfusion scintigraphies, to evaluate myocardial perfusion at rest and during ERCP. RESULTS: Ten patients completed the study. Eight patients had no sign of myocardial ischemia...... with either of the two methods, while two patients developed signs of ischemia during ERCP with both the Holter tape recording and on myocardial scintigraphy (P = 0.02). CONCLUSIONS: Patients undergoing ERCP may develop true myocardial ischemia with reduced myocardial blood flow. Although this is a small...

  6. Skin blood flow with elastic compressive extravehicular activity space suit.

    Science.gov (United States)

    Tanaka, Kunihiko; Gotoh, Taro M; Morita, Hironobu; Hargens, Alan R

    2003-10-01

    During extravehicular activity (EVA), current space suits are pressurized with 100% oxygen at approximately 222 mmHg. A tight elastic garment, or mechanical counter pressure (MCP) suit that generates pressure by compression, may have several advantages over current space suit technology. In this study, we investigated local microcirculatory effects produced with negative ambient pressure with an MCP sleeve. The MCP glove and sleeve generated pressures similar to the current space suit. MCP remained constant during negative pressure due to unchanged elasticity of the material. Decreased skin capillary blood flow and temperature during MCP compression was counteracted by greater negative pressure or a smaller pressure differential.

  7. Cerebral blood flow and oxidative metabolism during human endotoxemia

    DEFF Research Database (Denmark)

    Møller, Kirsten; Strauss, Gitte Irene; Qvist, Jesper;

    2002-01-01

    The proinflammatory cytokine, tumor necrosis factor-alpha (TNF-alpha), has been suggested to mediate septic encephalopathy through an effect on cerebral blood flow (CBF) and metabolism. The effect of an intravenous bolus of endotoxin on global CBF, metabolism, and net flux of cytokines and catech...... cerebral flux of TNF-alpha, interleukin (IL)-1beta, and IL-6 did not differ significantly from zero. Thus, high circulating levels of TNF-alpha during human endotoxemia do not induce a direct reduction in cerebral oxidative metabolism....

  8. Methylphenidate decreases regional cerebral blood flow in normal human subjects

    Energy Technology Data Exchange (ETDEWEB)

    Wang, G.J.; Volkow, N.D. (Brookhaven National Lab., Upton, NY (United States) SUNY, Stony Brook, NY (United States)); Fowler, J.S.; Ferrieri, R.; Schlyer, D.J.; Alexoff, D.; Warner, D.; Wolf, A.P.; Pappas, N.; King, P.; Wong, C. (Brookhaven National Lab., Upton, NY (United States)); Hitzemann, R.J. (SUNY, Stony Brook, NY (United States)); Lieberman, J. (Hillside Hospital, Glen Oaks, NY (United States))

    1994-01-01

    To assess the effects of methylphenidate (MP) on cerebral blood flow (CBF), 5 healthy males were studied using [sup 15]O-water and positron emission tomography before and after MP (0.5mg/kg iv). MP significantly decreased whole brain CBF at 5-10 minutes (25[+-]11%) and at 30 minutes (20[+-]10%) after its administration. Decrements in CBF were homogeneous throughout the brain (regional decrements 23-30%) and probably reflect the vasoactive properties of MP. The vasoactive properties of MP should be considered when prescribing this drug chronically and/or when giving it to subjects with cerebrovascular compromise.

  9. Study on animals‘ femur blood flow alteration under inadequate decompression with 133Xe isotope washout method

    Institute of Scientific and Technical Information of China (English)

    YuShao-Ning; TiaoWu-Xun; 等

    1998-01-01

    Animals' regional femur blood(F) alteration was studied under an inadequate decompression by using the inhaled isotope 133Xe washout method.Results showed that the average F on left and right side of minipigs' femur decreased from 15.4±1.8 and 16.9±2.0mg/(100g.min)(before exposure)to 10±1.8and 11.1±1.6mg(100mg.min)(after expposure for 1.5h under the pressure of 0.5 MPa and then decompression to normal with the rate of 0.03-0.04MPa/min)respectively;the blood flow of hematopoietic marrow tissues(f1) on both sides also decreased from 19.3±2.0 and 22.1±1.9ml(100mg.min)to 13.9±1.4 and 13.8±1.0ml(100mg.min).The exact same alteration also happened in the experiment on New Zealand rabbits.It indicates that inadequate decompression in hyperbaric exposure can give rise to decrease animals' one blood flow and insufficient bone blood supply serves as one of the reasons for causing decompressive osteonecrosis.

  10. Blood flow drives lumen formation by inverse membrane blebbing during angiogenesis in vivo.

    Science.gov (United States)

    Gebala, Véronique; Collins, Russell; Geudens, Ilse; Phng, Li-Kun; Gerhardt, Holger

    2016-04-01

    How vascular tubes build, maintain and adapt continuously perfused lumens to meet local metabolic needs remains poorly understood. Recent studies showed that blood flow itself plays a critical role in the remodelling of vascular networks, and suggested it is also required for the lumenization of new vascular connections. However, it is still unknown how haemodynamic forces contribute to the formation of new vascular lumens during blood vessel morphogenesis. Here we report that blood flow drives lumen expansion during sprouting angiogenesis in vivo by inducing spherical deformations of the apical membrane of endothelial cells, in a process that we have termed inverse blebbing. We show that endothelial cells react to these membrane intrusions by local and transient recruitment and contraction of actomyosin, and that this mechanism is required for single, unidirectional lumen expansion in angiogenic sprouts. Our work identifies inverse membrane blebbing as a cellular response to high external pressure. We show that in the case of blood vessels such membrane dynamics can drive local cell shape changes required for global tissue morphogenesis, shedding light on a pressure-driven mechanism of lumen formation in vertebrates.

  11. Complex blood flow quantification using real-time in vivo vector flow ultrasound

    DEFF Research Database (Denmark)

    Pedersen, Mads Møller; Pihl, Michael Johannes; Per, Haugaard;

    for the vector angle estimates was calculated for each box in every frame. For comparison three ultrasound experts evaluated the presence of complex flow in every box. The trial was blinded. For every sequence the mean standard deviation of the vector angle estimates were calculated for box1 {39......A new method to define and quantify complex blood flow is presented. The standard deviations of real-time in vivo vector flow angle estimates are used. Using vector flow ultrasound imaging both carotid bifurcations of two healthy volunteers were scanned. Scanning was performed with a 7.6 MHz linear...... transducer (8670, B-K Medical, Denmark) and a commercial vector flow ultrasound scanner (ProFocus 2202, B-K Medical). Eight video sequences of one cardiac cycle were obtained. In every frame boxes were placed to define the common carotid artery(box1) and the carotid bulb(box2). The standard deviation...

  12. Numerical Simulation of Unsteady Blood Flow through Capillary Networks.

    Science.gov (United States)

    Davis, J M; Pozrikidis, C

    2011-08-01

    A numerical method is implemented for computing unsteady blood flow through a branching capillary network. The evolution of the discharge hematocrit along each capillary segment is computed by integrating in time a one-dimensional convection equation using a finite-difference method. The convection velocity is determined by the local and instantaneous effective capillary blood viscosity, while the tube to discharge hematocrit ratio is deduced from available correlations. Boundary conditions for the discharge hematocrit at divergent bifurcations arise from the partitioning law proposed by Klitzman and Johnson involving a dimensionless exponent, q≥1. When q=1, the cells are partitioned in proportion to the flow rate; as q tends to infinity, the cells are channeled into the branch with the highest flow rate. Simulations are performed for a tree-like, perfectly symmetric or randomly perturbed capillary network with m generations. When the tree involves more than a few generations, a supercritical Hopf bifurcation occurs at a critical value of q, yielding spontaneous self-sustained oscillations in the absence of external forcing. A phase diagram in the m-q plane is presented to establish conditions for unsteady flow, and the effect of various geometrical and physical parameters is examined. For a given network tree order, m, oscillations can be induced for a sufficiently high value of q by increasing the apparent intrinsic viscosity, decreasing the ratio of the vessel diameter from one generation to the next, or by decreasing the diameter of the terminal vessels. With other parameters fixed, oscillations are inhibited by increasing m. The results of the continuum model are in excellent agreement with the predictions of a discrete model where the motion of individual cells is followed from inlet to outlet.

  13. Quantification of volumetric cerebral blood flow using hybrid laser speckle contract and optical coherence tomography (Conference Presentation)

    Science.gov (United States)

    Valim, Niksa; Dunn, Andrew K.

    2016-03-01

    Studying neurovascular blood flow function in cerebrovascular activities requires accurate visualization and characterization of blood flow volume as well as the dynamics of blood cells in microcirculation. In this study, we present a novel integration of laser speckle contrast imaging (LSCI) and spectral domain optical coherence tomography (SD-OCT) for rapid volumetric imaging of blood flow in cortical capillaries. LSCI uses the illumination of wide-field near infrared light (NIR) and monitors back scattered light to characterize the relative dynamics of blood flow in microcirculation. Absolute measurement of blood cells and blood volume requires high-resolution volumetric structural information. SD-OCT system uses coherence gating to measure scattered light from a small volume within high structural resolution. The structural imaging system rapidly assesses large number of capillaries for spatio-temporal tracking of red blood cells (RBC). A very fast-ultra resolution SD-OCT system was developed for imaging high-resolution volumetric samples. The system employed an ultra wideband light source (1310 ± 200 nm in wavelength) corresponding to an axial resolution of 3 micrometers in tissue. The spectrometer of the SD-OCT was customized for a maximum scanning rate of 147,000 line/s. We demonstrated a fast volumetric OCT angiography algorithm to visualize large numbers of vessels in a 2-mm deep sample volume. A LSCI system that has been developed previously in our group was integrated to the imaging system for the characterization of dynamic blood cells. The conjunction data from LSCI and SD-OCT systems imply the feasibility of accurate quantification of absolute cortical blood flow.

  14. Can perfusion CT assessment of primary colorectal adenocarcinoma blood flow at staging predict for subsequent metastatic disease? A pilot study

    Energy Technology Data Exchange (ETDEWEB)

    Goh, Vicky [Mount Vernon Hospital, Paul Strickland Scanner Centre, Northwood (United Kingdom); Halligan, Steve [University College Hospital, Department of Academic Radiology, London (United Kingdom); Wellsted, David M. [University of Hertfordshire, Health Research and Development Support Unit, Hatfield (United Kingdom); Bartram, Clive I. [St Mark' s Hospital, Intestinal Imaging Centre, Harrow (United Kingdom)

    2009-01-15

    We aimed to determine whether perfusion CT measurements at colorectal cancer staging may predict for subsequent metastatic relapse. Fifty two prospective patients underwent perfusion CT at staging to estimate tumour blood flow, blood volume, mean transit time, and permeability surface area product. Patients considered metastasis free and suitable for surgery underwent curative resection subsequently. At final analysis, a median of 48.6 months post-surgery, patients were divided into those who remained disease free, and those with subsequent metastases. Vascular parameters for these two groups were compared using t-testing, and receiver operator curve analysis was performed to determine the sensitivity and specificity of these vascular parameters for predicting metastases. Thirty seven (71%) patients underwent curative surgery; data were available for 35: 26 (74%) remained disease free; 9 (26%) recurred (8 metastatic, 1 local). Tumour blood flow differed significantly between disease-free and metastatic patients (76.0 versus 45.7 ml/min/100 g tissue; p=0.008). With blood flow <64 ml/min/100 g tissue, sensitivity and specificity (95% CI) for development of metastases were 100% (60-100%) and 73% (53-87%), respectively. Our preliminary findings suggest that primary tumour blood flow might potentially be a useful predictor warranting further study. (orig.)

  15. Calibration of diffuse correlation spectroscopy blood flow index with venous-occlusion diffuse optical spectroscopy in skeletal muscle

    Science.gov (United States)

    Li, Zhe; Baker, Wesley B.; Parthasarathy, Ashwin B.; Ko, Tiffany S.; Wang, Detian; Schenkel, Steven; Durduran, Turgut; Li, Gang; Yodh, Arjun G.

    2015-12-01

    We investigate and assess the utility of a simple scheme for continuous absolute blood flow monitoring based on diffuse correlation spectroscopy (DCS). The scheme calibrates DCS using venous-occlusion diffuse optical spectroscopy (VO-DOS) measurements of arm muscle tissue at a single time-point. A calibration coefficient (γ) for the arm is determined, permitting conversion of DCS blood flow indices to absolute blood flow units, and a study of healthy adults (N=10) is carried out to ascertain the variability of γ. The average DCS calibration coefficient for the right (i.e., dominant) arm was γ=(1.24±0.15)×108 (mL·100 mL-1·min-1)/(cm2/s). However, variability can be significant and is apparent in our site-to-site and day-to-day repeated measurements. The peak hyperemic blood flow overshoot relative to baseline resting flow was also studied following arm-cuff ischemia; excellent agreement between VO-DOS and DCS was found (R2=0.95, slope=0.94±0.07, mean difference=-0.10±0.45). Finally, we show that incorporation of subject-specific absolute optical properties significantly improves blood flow calibration accuracy.

  16. Human red blood cells deformed under thermal fluid flow.

    Science.gov (United States)

    Foo, Ji-Jinn; Chan, Vincent; Feng, Zhi-Qin; Liu, Kuo-Kang

    2006-03-01

    The flow-induced mechanical deformation of a human red blood cell (RBC) during thermal transition between room temperature and 42.0 degrees C is interrogated by laser tweezer experiments. Based on the experimental geometry of the deformed RBC, the surface stresses are determined with the aid of computational fluid dynamics simulation. It is found that the RBC is more deformable while heating through 37.0 degrees C to 42.0 degrees C, especially at a higher flow velocity due to a thermal-fluid effect. More importantly, the degree of RBC deformation is irreversible and becomes softer, and finally reaches a plateau (at a uniform flow velocity U > 60 microm s(-1)) after the heat treatment, which is similar to a strain-hardening dominated process. In addition, computational simulated stress is found to be dependent on the progression of thermotropic phase transition. Overall, the current study provides new insights into the highly coupled temperature and hydrodynamic effects on the biomechanical properties of human erythrocyte in a model hydrodynamic flow system.

  17. Building a 3D Virtual Liver: Methods for Simulating Blood Flow and Hepatic Clearance on 3D Structures

    Science.gov (United States)

    Rezania, Vahid; Tuszynski, Jack

    2016-01-01

    In this paper, we develop a spatio-temporal modeling approach to describe blood and drug flow, as well as drug uptake and elimination, on an approximation of the liver. Extending on previously developed computational approaches, we generate an approximation of a liver, which consists of a portal and hepatic vein vasculature structure, embedded in the surrounding liver tissue. The vasculature is generated via constrained constructive optimization, and then converted to a spatial grid of a selected grid size. Estimates for surrounding upscaled lobule tissue properties are then presented appropriate to the same grid size. Simulation of fluid flow and drug metabolism (hepatic clearance) are completed using discretized forms of the relevant convective-diffusive-reactive partial differential equations for these processes. This results in a single stage, uniformly consistent method to simulate equations for blood and drug flow, as well as drug metabolism, on a 3D structure representative of a liver. PMID:27649537

  18. Evaluation of the Effects of Acupuncture on Blood Flow in Humans with Ultrasound Color Doppler Imaging

    OpenAIRE

    Takayama, Shin; WATANABE, Masashi; Kusuyama, Hiroko; Nagase, Satoru; Seki, Takashi; Nakazawa, Toru; Yaegashi, Nobuo

    2012-01-01

    Color Doppler imaging (CDI) can be used to noninvasively create images of human blood vessels and quantitatively evaluate blood flow in real-time. The purpose of this study was to assess the effects of acupuncture on the blood flow of the peripheral, mesenteric, and retrobulbar arteries by CDI. Statistical significance was defined as P values less than 0.05. Blood flow in the radial and brachial arteries was significantly lower during needle stimulation on LR3 than before in healthy volunteer...

  19. Clustering of microscopic particles in constricted blood flow

    CERN Document Server

    Bächer, Christian; Gekle, Stephan

    2016-01-01

    A mixed suspension of red blood cells (RBCs) and microparticles flows through a cylindrical channel with a constriction mimicking a stenosed blood vessel. Our three-dimensional Lattice-Boltzmann simulations show that the RBCs are depleted right ahead and after the constriction. Although the RBC mean concentration (hematocrit) is 16.5% or 23.7%, their axial concentration profile is very similar to that of isolated tracer particles flowing along the central axis. Most importantly, however, we find that the stiff microparticles exhibit the opposite behavior. Arriving on a marginated position near the channel wall, they can pass through the constriction only if they find a suitable gap to dip into the dense plug of RBCs occupying the channel center. This leads to a prolonged dwell time and, as a consequence, to a pronounced increase in microparticle concentration right in front of the constriction. For biochemically active particles such as drug delivery agents or activated platelets this clustering may lead to p...

  20. Multiscale modeling and simulation of brain blood flow

    Science.gov (United States)

    Perdikaris, Paris; Grinberg, Leopold; Karniadakis, George Em

    2016-02-01

    The aim of this work is to present an overview of recent advances in multi-scale modeling of brain blood flow. In particular, we present some approaches that enable the in silico study of multi-scale and multi-physics phenomena in the cerebral vasculature. We discuss the formulation of continuum and atomistic modeling approaches, present a consistent framework for their concurrent coupling, and list some of the challenges that one needs to overcome in achieving a seamless and scalable integration of heterogeneous numerical solvers. The effectiveness of the proposed framework is demonstrated in a realistic case involving modeling the thrombus formation process taking place on the wall of a patient-specific cerebral aneurysm. This highlights the ability of multi-scale algorithms to resolve important biophysical processes that span several spatial and temporal scales, potentially yielding new insight into the key aspects of brain blood flow in health and disease. Finally, we discuss open questions in multi-scale modeling and emerging topics of future research.

  1. Multiscale modeling and simulation of brain blood flow

    Energy Technology Data Exchange (ETDEWEB)

    Perdikaris, Paris, E-mail: parisp@mit.edu [Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Grinberg, Leopold, E-mail: leopoldgrinberg@us.ibm.com [IBM T.J Watson Research Center, 1 Rogers St, Cambridge, Massachusetts 02142 (United States); Karniadakis, George Em, E-mail: george-karniadakis@brown.edu [Division of Applied Mathematics, Brown University, Providence, Rhode Island 02912 (United States)

    2016-02-15

    The aim of this work is to present an overview of recent advances in multi-scale modeling of brain blood flow. In particular, we present some approaches that enable the in silico study of multi-scale and multi-physics phenomena in the cerebral vasculature. We discuss the formulation of continuum and atomistic modeling approaches, present a consistent framework for their concurrent coupling, and list some of the challenges that one needs to overcome in achieving a seamless and scalable integration of heterogeneous numerical solvers. The effectiveness of the proposed framework is demonstrated in a realistic case involving modeling the thrombus formation process taking place on the wall of a patient-specific cerebral aneurysm. This highlights the ability of multi-scale algorithms to resolve important biophysical processes that span several spatial and temporal scales, potentially yielding new insight into the key aspects of brain blood flow in health and disease. Finally, we discuss open questions in multi-scale modeling and emerging topics of future research.

  2. Alterations of Regional Cerebral Blood Flow in Major Depressive Disorder

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Won Hyoung; Chung, Yong An; Seo, Ye Young; Yoo, Ik Dong; Na, Sae Jung; Jung, Hyun Suk; Kim, Ki Jun [College of Medicine, The Catholic University of Korea, Seoul (Korea, Republic of)

    2009-04-15

    The authors analyzed how the regional cerebral blood flow (rCBF) findings of patients with major depression differ from the normal control, and our results were compared to previous reports. Twelve patients fulfilling DSM-IV criteria for major depression who were off all psychotropic medications for > 4 weeks (male: 7, female: 5, age range: 19approx52 years, average age: 29.3+-9.9 years) and 14 normal volunteers (male: 8, female: 6, age range: 19approx53 years, average age: 31.4+-9.2 years) were recruited. Images of brain perfusion SPECT were obtained using Tc-99m ECD and patterns of the rCBF were compared between patients with major depression and the healthy control subjects. The patients with major depression showed increase of the r-CBF in right lingual gyrus, right fusiform gyrus, left lingual gyrus, left precuneus, and left superior temporal gyrus, and showed decrease of r-CBF in right pons, left medial frontal gyrus, cingulate gyrus of left limbic lobe, cingulate gyrus of right frontal lobe, and cingulate gyrus of right limbic lobe compared to the normal control. The Tc-99m ECD brain perfusion SPECT findings in our study did not differ from the previously reported regional cerebral blood flow pattern of patients with major depression. Especially, decreased rCBF pattern typical to major depression patients in the right pons, left medial frontal gyrus, and cingulate regions was clearly demonstrated

  3. Laser Doppler flowmetry: reproducibility, reliability, and diurnal blood flow variations.

    Science.gov (United States)

    Roeykens, Herman J J; Deschepper, Ellen; De Moor, Roeland J G

    2016-08-01

    The aim of this investigation was (1) to evaluate the reliability of laser Doppler flowmetry (LDF) taking into consideration the use of a silicone splint and the inclination of the probe towards the buccal surface of a human tooth and (2) to determine whether diurnal variations of pulpal blood flow can be registered by means of LDF. Forty-one splints were made by one and the same principal investigator for the registration of pulpal blood flow in vivo in a maxillary right central incisor. Thirty dentists, without experience in LDF recording, were then asked to drill a right-angled shaft in a pre-manufactured splint with a referral point at 2 mm from the enamel-cement border central on the buccal surface of the right central upper incisor. The remaining 11 splints were handled by the principal investigator. The shafts in the 30 splints were analysed using Cone Beam CT imaging of the axial and sagittal angles and compared these to the 11 shafts prepared by the trained principal investigator. LDF was recorded for 90 s in each splint and statistically analysed. LDF values without the use of a splint were statistically significantly different (p < 0.05) and the variance was greater, indicating the superiority of splint use. Significant diurnal variations on LDF values were observed, indicating that special attention should be paid to registration during the day, especially when multiple measurements are to be compared. PMID:27184153

  4. Altered Cerebral Blood Flow Covariance Network in Schizophrenia.

    Science.gov (United States)

    Liu, Feng; Zhuo, Chuanjun; Yu, Chunshui

    2016-01-01

    Many studies have shown abnormal cerebral blood flow (CBF) in schizophrenia; however, it remains unclear how topological properties of CBF network are altered in this disorder. Here, arterial spin labeling (ASL) MRI was employed to measure resting-state CBF in 96 schizophrenia patients and 91 healthy controls. CBF covariance network of each group was constructed by calculating across-subject CBF covariance between 90 brain regions. Graph theory was used to compare intergroup differences in global and nodal topological measures of the network. Both schizophrenia patients and healthy controls had small-world topology in CBF covariance networks, implying an optimal balance between functional segregation and integration. Compared with healthy controls, schizophrenia patients showed reduced small-worldness, normalized clustering coefficient and local efficiency of the network, suggesting a shift toward randomized network topology in schizophrenia. Furthermore, schizophrenia patients exhibited altered nodal centrality in the perceptual-, affective-, language-, and spatial-related regions, indicating functional disturbance of these systems in schizophrenia. This study demonstrated for the first time that schizophrenia patients have disrupted topological properties in CBF covariance network, which provides a new perspective (efficiency of blood flow distribution between brain regions) for understanding neural mechanisms of schizophrenia.

  5. Influence of postmortem time on the outcome of blood cultures among cadaveric tissue donors.

    Science.gov (United States)

    Saegeman, V; Verhaegen, J; Lismont, D; Verduyckt, B; De Rijdt, T; Ectors, N

    2009-02-01

    Tissue banks provide tissues of human cadaver donors for transplantation. The maximal time limit for tissue retrieval has been set at 24 h postmortem. This study aimed at evaluating the evidence for this limit from a microbiological point of view. The delay of growth in postmortem blood cultures, the identification of the species isolated and clinical/environmental factors were investigated among 100 potential tissue donors. No significant difference was found in the rate of donors with grown blood cultures within (25/65=38%) compared with after (24/65=37%) 24 h of death. Coagulase-negative staphylococci and gastro-intestinal microorganisms were isolated within and after 24 h of death. Two factors--antimicrobial therapy and "delay before body cooling"--were significantly inversely related with donors' blood culture results. From a microbiological point of view, there is no evidence for avoiding tissue retrieval among donors after 24 h of death.

  6. Effects of Cortical Spreading Depression on Synaptic Activity, Blood Flow and Oxygen Consumption in Rat Cerebral Cortex

    DEFF Research Database (Denmark)

    Hansen, Henning Piilgaard

    2010-01-01

    As the title of this thesis indicates I have during my PhD studied the effects of cortical spreading depression (CSD) on synaptic activity, blood flow and oxygen consumption in rat cerebral cortex. This was performed in vivo using an open cranial window approach in anesthetized rats. I applied...... Laser-Doppler Flowmetry for measurements of cerebral blood flow, glass microelectrodes for recording of synaptic activity – local field potentials – and ongoing cortical electrical activity and a Clark type electrode for measurements of tissue partial pressure of oxygen (tpO2). Offline calculations...... of cerebral metabolic rate of oxygen (CMRO2) were performed using a compartment model as described Gjedde1. In the first study we characterized the frequency dependency of evoked responses of the transcallosal fiber network (TC) in the somatosensory cortex concerning: synaptic activity, cerebral blood flow...

  7. Two and Three Dimensional Blood Flow Simulations in Different Types of Blood Vessels

    Directory of Open Access Journals (Sweden)

    Balazs ALBERT

    2015-12-01

    Full Text Available In this paper we present a synthesis of our results obtained on blood flow simulation in different types of blood vessels. We present first some remarks on the wall shear stress (WSS in the case of a human abdominal aortic aneurysm (AAA, and then we concentrate on the mechanical conditions which would lead to the “rupture” of the vascular vessel with aneurysm and implicitly to a possible stroke. We also make some investigations on the Fahraeus-Lindqvist effect in arterioles. Considering an axial-symmetric reservoir full of blood and which is linked to an arteriole (with the same particular geometry, we have pointed out the concentration of the red blood cells in this arteriole towards the core of the vessel. To improve our work we have considered a real three-dimensional geometry, which is a serious jump versus our previous results, where only the axial-symmetric geometries were considered. In this respect we have reconsidered the case of a carotid artery stenosis with and without a stent.

  8. Platelet-Rich Blood Derivatives for Stem Cell-Based Tissue Engineering and Regeneration

    NARCIS (Netherlands)

    Masoudi, E.A.; Ribas, J.; Kaushik, G.; Leijten, J.C.H.; Khademhosseini, A.

    2016-01-01

    Platelet-rich blood derivatives have been widely used in different fields of medicine and stem cell-based tissue engineering. They represent natural cocktails of autologous growth factors, which could provide an alternative for recombinant protein-based approaches. Platelet-rich blood derivatives, s

  9. Intensive blood pressure control affects cerebral blood flow in type 2 diabetes mellitus patients

    DEFF Research Database (Denmark)

    Kim, Yu-Sok; Davis, Shyrin C A T; Truijen, Jasper;

    2011-01-01

    Type 2 diabetes mellitus is associated with microvascular complications, hypertension, and impaired dynamic cerebral autoregulation. Intensive blood pressure (BP) control in hypertensive type 2 diabetic patients reduces their risk of stroke but may affect cerebral perfusion. Systemic hemodynamic...... variables and transcranial Doppler-determined cerebral blood flow velocity (CBFV), cerebral CO2 responsiveness, and cognitive function were determined after 3 and 6 months of intensive BP control in 17 type 2 diabetic patients with microvascular complications (T2DM+), in 18 diabetic patients without (T2DM......-) microvascular complications, and in 16 nondiabetic hypertensive patients. Cerebrovascular reserve capacity was lower in T2DM+ versus T2DM- and nondiabetic hypertensive patients (4.6±1.1 versus 6.0±1.6 [P

  10. A simple model of cerebral blood flow dependence on arterial blood pressure

    CERN Document Server

    Gersten, Alexander

    2011-01-01

    It is shown that the dependence of the cerebral blood flow (CBF) on mean arterial blood pressure (MABP) can be described with a simple model having the following assumptions. Below certain MABP (denoted as MABP1) there are no autoregulatory or feedback mechanisms influencing CBF. Between MABP1 and MABP2 (MABP at which breakthrough accurs) there is a linear (on MABP) dependent feedback with a sloap depending very much on the individual considered. The classical autoregulation model with a plateau in between MABP1 and MABP2 is a particular case of this model. The model describes well the experiments performed on dogs (Harper 1966), for which the individual feedback sloap parameter varied to great extent, indicating the importance of mesurments on individuals against averaged mesurments (or measurments on diffent individuals) which superficially support the classical autoregulation. New effect of decreased CBF, while increasing MABP, was observed.

  11. Determinants of resting cerebral blood flow in sickle cell disease.

    Science.gov (United States)

    Bush, Adam M; Borzage, Matthew T; Choi, Soyoung; Václavů, Lena; Tamrazi, Benita; Nederveen, Aart J; Coates, Thomas D; Wood, John C

    2016-09-01

    Stroke is common in children with sickle cell disease and results from an imbalance in oxygen supply and demand. Cerebral blood flow (CBF) is increased in patients with sickle cell disease to compensate for their anemia, but adequacy of their oxygen delivery has not been systematically demonstrated. This study examined the physiological determinants of CBF in 37 patients with sickle cell disease, 38 ethnicity matched control subjects and 16 patients with anemia of non-sickle origin. Cerebral blood flow was measured using phase contrast MRI of the carotid and vertebral arteries. CBF increased inversely to oxygen content (r(2)  = 0.69, P Brain oxygen delivery, the product of CBF and oxygen content, was normal in all groups. Brain composition, specifically the relative amounts of grey and white matter, was the next strongest CBF predictor, presumably by influencing cerebral metabolic rate. Grey matter/white matter ratio and CBF declined monotonically until the age of 25 in all subjects, consistent with known maturational changes in brain composition. Further CBF reductions were observed with age in subjects older than 35 years of age, likely reflecting microvascular aging. On multivariate regression, CBF was independent of disease state, hemoglobin S, hemoglobin F, reticulocyte count and cell free hemoglobin, suggesting that it is regulated similarly in patients and control subjects. In conclusion, sickle cell disease patients had sufficient oxygen delivery at rest, but accomplish this only by marked increases in their resting CBF, potentially limiting their ability to further augment flow in response to stress. Am. J. Hematol. 91:912-917, 2016. © 2016 Wiley Periodicals, Inc. PMID:27263497

  12. Correlation study of uterine spiral artery blood flow characteristics with placental development and hypoxia in patients with preeclampsia

    Institute of Scientific and Technical Information of China (English)

    Rong Ma

    2016-01-01

    Objective:To study the correlation of uterine spiral artery blood flow characteristics with placental development and hypoxia in patients with preeclampsia.Methods:A total of 66 patients diagnosed with preeclampsia in our hospital between June 2013 and May 2016 were selected as the preeclampsia group (PE group) of the study and healthy women who gave birth in our hospital during the same period were selected as control group. At 32-37 weeks of gestation, uterine spiral artery ultrasonography was conducted to determine blood flow parameters PI, RI and S/D, and peripheral blood was collected to separate mononuclear cells and then determine CTLA-4 and CD28 mRNA level; after childbirth, placenta tissue was collect to determine the levels of placental development-related cytokines and apoptotic molecules.Results: Uterine spiral artery RI, PI and S/D of PE group were significantly higher than those of control group; PLGF, NGF, EGF, IGF-I, VEGF, Xiap, Survivin, bcl-2 and CD28 content in placenta tissue of PE group were significantly lower than those of control group and negatively correlated with uterine spiral artery PI, RI and S/D while GDF-15, caspase-3, caspase-9 and CTLA-4 content were significantly higher than those of control group and positively correlated with uterine spiral artery PI, RI and S/D; CTLA-4 mRNA level in peripheral blood mononuclear cells of PE group was significantly higher than that of control group and positively correlated with uterine spiral artery were PI, RI and S/D while CD28 mRNA level was significantly lower than that of control group and negatively correlated with uterine spiral artery PI, RI and S/D.Conclusion:Uterine spiral artery blood flow resistance increases and blood flow volume decreases in patients with preeclampsia, and the above blood flow characteristics will hinder the placental development, induce cell apoptosis and aggravate the placental hypoxia.

  13. Pulsed photoacoustic techniques and glucose determination in human blood and tissue

    OpenAIRE

    Zhao, Z.

    2002-01-01

    Abstract Determination of blood glucose level is a frequently occurring procedure in diabetes care. As the most common method involves collecting blood drops for chemical analysis, it is invasive and liable to afflict a degree of pain and cause a skin injury. To eliminate these disadvantages, this thesis focuses on pulsed photoacoustic techniques, which have potential ability in non-invasive blood glucose measurement. The fundamental theory of photoacoustics in liquid and soft tissue ...

  14. Upper limit of cerebral blood flow autoregulation in experimental renovascular hypertension in the baboon

    DEFF Research Database (Denmark)

    Strandgaard, S; Jones, J V; MacKenzie, E T;

    1975-01-01

    The effect of arterial hypertension on cerebral blood flow was studied by the intracarotid 133Xe clearance method in baboons. The arterial blood pressure was raised in gradual steps with angiotensin. Baboons with renal hypertension of 8-12 weeks duration were studied along with normotensive baboons....... In initially normotensive baboons, cerebral blood flow remained constant until the mean arterial blood pressure had risen to the range of 140 to 154 mm Hg; thereafter cerebral blood flow increased with each rise in mean arterial blood pressure. In the chronically hypertensive baboons, cerebral blood flow...... remained constant until the mean arterial blood pressure had been elevated to the range of 155 to 169 mm Hg. Thus, in chronic hypertension it appears that there are adaptive changes in the cerebral circulation which may help to protect the brain from further increases in arterial blood pressure....

  15. Sympathetic reflex control of subcutaneous blood flow in tetraplegic man during postural changes

    DEFF Research Database (Denmark)

    Skagen, K; Jensen, K; Henriksen, O;

    1982-01-01

    1. The effect of head-up tilt upon subcutaneous blood flow in the distal arm and leg was studied in 12 patients with complete traumatic spinal cord transection at the cervical level. 2. Blood flow was measured by the local 133Xe washout technique. 3. Leg lowering induced a 47% decrease in blood f...

  16. Middle cerebral artery blood velocity and cerebral blood flow and O2 uptake during dynamic exercise

    DEFF Research Database (Denmark)

    Madsen, P L; Sperling, B K; Warming, T;

    1993-01-01

    Results obtained by the 133Xe clearance method with external detectors and by transcranial Doppler sonography (TCD) suggest that dynamic exercise causes an increase of global average cerebral blood flow (CBF). These data are contradicted by earlier data obtained during less-well-defined conditions....... To investigate this controversy, we applied the Kety-Schmidt technique to measure the global average levels of CBF and cerebral metabolic rate of oxygen (CMRO2) during rest and dynamic exercise. Simultaneously with the determination of CBF and CMRO2, we used TCD to determine mean maximal flow velocity...... in the middle cerebral artery (MCA Vmean). For values of CBF and MCA Vmean a correction for an observed small drop in arterial PCO2 was carried out. Baseline values for global CBF and CMRO2 were 50.7 and 3.63 ml.100 g-1.min-1, respectively. The same values were found during dynamic exercise, whereas a 22% (P

  17. Theory to predict shear stress on cells in turbulent blood flow.

    Science.gov (United States)

    Morshed, Khandakar Niaz; Bark, David; Forleo, Marcio; Dasi, Lakshmi Prasad

    2014-01-01

    Shear stress on blood cells and platelets transported in a turbulent flow dictates the fate and biological activity of these cells. We present a theoretical link between energy dissipation in turbulent flows to the shear stress that cells experience and show that for the case of physiological turbulent blood flow: (a) the Newtonian assumption is valid, (b) turbulent eddies are universal for the most complex of blood flow problems, and (c) shear stress distribution on turbulent blood flows is possibly universal. Further we resolve a long standing inconsistency in hemolysis between laminar and turbulent flow using the theoretical framework. This work demonstrates that energy dissipation as opposed to bulk shear stress in laminar or turbulent blood flow dictates local mechanical environment of blood cells and platelets universally.

  18. Effect of labetalol on cerebral blood flow and middle cerebral arterial flow velocity in healthy volunteers

    DEFF Research Database (Denmark)

    Schroeder, T; Schierbeck, Jens; Howardy, P;

    1991-01-01

    The effect of labetalol, a combined alpha- and beta-adrenoceptor antagonist, on the cerebral circulation was investigated in 7 normotensive subjects. Cerebral blood flow (CBF) was measured with the intravenous 133Xe method and mean flow velocity (Vmean) in the middle cerebral artery was determined...... using transcranial Doppler (TCD) ultrasound. Examination was performed before and then 15, 60 and 120 min after 0.75 mg/kg i.v. labetalol. Reactivity to inhalation of 5% CO2 in air was studied before, and again 90 min after labetalol administration. Neither CBF nor Vmean changed following labetalol...

  19. Blood BDNF concentrations reflect brain-tissue BDNF levels across species

    DEFF Research Database (Denmark)

    Klein, Anders B; Williamson, Rebecca; Santini, Martin A;

    2011-01-01

    Brain-derived neurotrophic factor (BDNF) is involved in synaptic plasticity, neuronal differentiation and survival of neurons. Observations of decreased serum BDNF levels in patients with neuropsychiatric disorders have highlighted the potential of BDNF as a biomarker, but so far there have been...... no studies directly comparing blood BDNF levels to brain BDNF levels in different species. We examined blood, serum, plasma and brain-tissue BDNF levels in three different mammalian species: rat, pig, and mouse, using an ELISA method. As a control, we included an analysis of blood and brain tissue from...

  20. A lumped-parameter model to investigate the effect of plantar pressure on arterial blood flow in a diabetic foot.

    Science.gov (United States)

    Hahn, C; Mahajan, A; Chu, T; Schoen, M

    2007-08-01

    This paper presents a lumped-parameter model for the big-toe region that investigates the effect of plantar pressure on the diameter of the blood vessels, specifically the arteries, in the presence of arterial and/or tissue changes. The model developed in this paper uses a multi-domain energy system approach to develop the lumped-parameter differential equations. Blood flow is modelled as fluidic flow through compliant pipes that have inertia, stiffness, and damping. The tissue material is treated as a soft compliant material that transmits the external force to the blood vessels. Conclusions have been drawn to show the effect of plantar pressure, tissue damage, and their combination on the diameter of the blood vessels. The principles used here can be used to model the entire foot and the model used to investigate the effect of plantar pressure, tissue damage, and arterial changes on different parts of the foot. The work presented here may also have applications in other vascular diseases. PMID:17937206

  1. Renal blood flow distribution during E. coli endotoxin shock in dog.

    Science.gov (United States)

    Kirkebø, A; Tyssebotn, I

    1980-04-01

    The effect of endotoxin on renal blood flow distribution was studied in anesthetized dogs. Renal blood flow was measured as hydrogen clearance by platinum electrodes placed in outer and in inner halves of cortex and by electromagnetic flowmeter. Intravenous injection of E. coli endotoxin, 3-5 mg/kg b. wt., promptly reduced arterial blood pressure (AP) and renal blood flow. After a transient increase for 45 min AP and renal blood flow declined to about 50% of the control 2 1/2-3 h after injection. The reduction in outer cortical blood flow (OCF) was not significantly different from the reduction in inner cortical blood flow (ICF). The hematocrit (Hct) increased from 40.1 +/- 3.8% to 54.6 +/- 8%, but mean renal vascular resistance did not change. Total plasma protein concentration was not significantly elevated. A marked local flow variability was observed in some periods during the phase of shock with declining AP and total renal blood flow at high Hct. Thus renal blood flow showed phasic changes, but the OCF/ICF ratio was not changed during endotoxin shock. Local blood flow instability was observed periodically at high Hct. PMID:6998257

  2. Flow measurements in a blood-perfused collagen vessel using x-ray micro-particle image velocimetry.

    Science.gov (United States)

    Antoine, Elizabeth; Buchanan, Cara; Fezzaa, Kamel; Lee, Wah-Keat; Rylander, M Nichole; Vlachos, Pavlos

    2013-01-01

    Blood-perfused tissue models are joining the emerging field of tumor engineering because they provide new avenues for modulation of the tumor microenvironment and preclinical evaluation of the therapeutic potential of new treatments. The characterization of fluid flow parameters in such in-vitro perfused tissue models is a critical step towards better understanding and manipulating the tumor microenvironment. However, traditional optical flow measurement methods are inapplicable because of the opacity of blood and the thickness of the tissue sample. In order to overcome the limitations of optical method we demonstrate the feasibility of using phase-contrast x-ray imaging to perform microscale particle image velocimetry (PIV) measurements of flow in blood perfused hydrated tissue-representative microvessels. However, phase contrast x-ray images significantly depart from the traditional PIV image paradigm, as they have high intensity background, very low signal-to-noise ratio, and volume integration effects. Hence, in order to achieve accurate measurements special attention must be paid to the image processing and PIV cross-correlation methodologies. Therefore we develop and demonstrate a methodology that incorporates image preprocessing as well as advanced PIV cross-correlation methods to result in measured velocities within experimental uncertainty.

  3. Flow measurements in a blood-perfused collagen vessel using x-ray micro-particle image velocimetry.

    Directory of Open Access Journals (Sweden)

    Elizabeth Antoine

    Full Text Available Blood-perfused tissue models are joining the emerging field of tumor engineering because they provide new avenues for modulation of the tumor microenvironment and preclinical evaluation of the therapeutic potential of new treatments. The characterization of fluid flow parameters in such in-vitro perfused tissue models is a critical step towards better understanding and manipulating the tumor microenvironment. However, traditional optical flow measurement methods are inapplicable because of the opacity of blood and the thickness of the tissue sample. In order to overcome the limitations of optical method we demonstrate the feasibility of using phase-contrast x-ray imaging to perform microscale particle image velocimetry (PIV measurements of flow in blood perfused hydrated tissue-representative microvessels. However, phase contrast x-ray images significantly depart from the traditional PIV image paradigm, as they have high intensity background, very low signal-to-noise ratio, and volume integration effects. Hence, in order to achieve accurate measurements special attention must be paid to the image processing and PIV cross-correlation methodologies. Therefore we develop and demonstrate a methodology that incorporates image preprocessing as well as advanced PIV cross-correlation methods to result in measured velocities within experimental uncertainty.

  4. New noninvasive quantitative assessment of cerebral blood flow using N-isopropyl-(iodine 123)p-iodoamphetamine

    International Nuclear Information System (INIS)

    The use of a nomogram is described as a new noninvasive quantitative assessment of cerebral blood flow using N-isopropyl-(123I)p-iodoamphetamine (IMP) and single-photon emission computed tomography. The nomogram was constructed from a computer analysis of the flow value relative to varying washout rate of brain activities between early and late tomographic images, and partition coefficient between brain tissue and blood. The validity of this method was evaluated in normal volunteers and in patients with cerebrovascular disorders by comparing the cortical flow values (Y) estimated from the IMP-nomogram with initial slope indices (X) by the 133Xe inhalation method. A significant correlation (N = 42, r = 0.88, P less than .001) was demonstrated between them, and the regression line was Y = 1.6X-7. A development and confirmation of this method made it possible to measure flow values noninvasively with the use of IMP

  5. Pulsatile blood flow in human bone assessed by laser-Doppler flowmetry and the interpretation of photoplethysmographic signals

    International Nuclear Information System (INIS)

    Human bone blood flow, mean blood speed and the number of moving red blood cells were assessed (in arbitrary units), as a function of time, during one cardiac cycle. The measurements were obtained non-invasively on five volunteers by laser-Doppler flowmetry at large interoptode spacing. The investigated bones included: patella, clavicle, tibial diaphysis and tibial malleolus. As hypothesized, we found that in all bones the number of moving cells remains constant during cardiac cycles. Therefore, we concluded that the pulsatile nature of blood flow must be completely determined by the mean blood speed and not by changes in blood volume (vessels dilation). Based on these results, it is finally demonstrated using a mathematical model (derived from the radiative transport theory) that photoplethysmographic (PPG) pulsations observed by others in the literature, cannot be generated by oscillations in blood oxygen saturation, which is physiologically linked to blood speed. In fact, possible oxygen saturation changes during pulsations decrease the amplitude of PPG pulsations due to specific features of the PPG light source. It is shown that a variation in blood oxygen saturation of 3% may induce a negative change of ∼1% in the PPG signal. It is concluded that PPG pulsations are determined by periodic ‘positive’ changes of the reduced scattering coefficient of the tissue and/or the absorption coefficient at constant blood volume. No explicit experimental PPG measurements have been performed. As a by-product of this study, an estimation of the arterial pulse wave velocity obtained from the analysis of the blood flow pulsations give a value of 7.8 m s−1 (95% confidence interval of the sample mean distribution: [6.7, 9.5] m s−1), which is perfectly compatible with data in the literature. We hope that this note will contribute to a better understanding of PPG signals and to further develop the domain of the vascular physiology of human bone. (note)

  6. Cell-cell interaction in blood flow in patients with coronary heart disease (in vitro study)

    Science.gov (United States)

    Malinova, Lidia I.; Simonenko, Georgy V.; Denisova, Tatyana P.; Tuchin, Valery V.

    2007-02-01

    Blood cell-cell and cell-vessel wall interactions are one of the key patterns in blood and vascular pathophysiology. We have chosen the method of reconstruction of pulsative blood flow in vitro in the experimental set. Blood flow structure was studied by PC integrated video camera with following slide by slide analysis. Studied flow was of constant volumetric blood flow velocity (1 ml/h). Diameter of tube in use was comparable with coronary arteries diameter. Glucose solution and unfractured heparin were used as the nonspecial irritants of studied flow. Erythrocytes space structure in flow differs in all groups of patients in our study (men with stable angina pectoris (SAP), myocardial infarction (MI) and practically healthy men (PHM). Intensity of erythrocytes aggregate formation was maximal in patients with SAP, but time of their "construction/deconstruction" at glucose injection was minimal. Phenomena of primary clotting formation in patients with SAP of high function class was reconstructed under experimental conditions. Heparin injection (10 000 ED) increased linear blood flow velocity both in patients with SAP, MI and PHP but modulated the cell profile in the flow. Received data correspond with results of animal model studies and noninvasive blood flow studies in human. Results of our study reveal differences in blood flow structure in patients with coronary heart disease and PHP under irritating conditions as the possible framework of metabolic model of coronary blood flow destabilization.

  7. Combined blood/tissue analysis for cancer biomarker discovery: application to renal cell carcinoma.

    Science.gov (United States)

    Johann, Donald J; Wei, Bih-Rong; Prieto, DaRue A; Chan, King C; Ye, Xiaying; Valera, Vladimir A; Simpson, R Mark; Rudnick, Paul A; Xiao, Zhen; Issaq, Haleem J; Linehan, W Marston; Stein, Stephen E; Veenstra, Timothy D; Blonder, Josip

    2010-03-01

    A method that relies on subtractive tissue-directed shot-gun proteomics to identify tumor proteins in the blood of a patient newly diagnosed with cancer is described. To avoid analytical and statistical biases caused by physiologic variability of protein expression in the human population, this method was applied on clinical specimens obtained from a single patient diagnosed with nonmetastatic renal cell carcinoma (RCC). The proteomes extracted from tumor, normal adjacent tissue and preoperative plasma were analyzed using 2D-liquid chromatography-mass spectrometry (LC-MS). The lists of identified proteins were filtered to discover proteins that (i) were found in the tumor but not normal tissue, (ii) were identified in matching plasma, and (iii) whose spectral count was higher in tumor tissue than plasma. These filtering criteria resulted in identification of eight tumor proteins in the blood. Subsequent Western-blot analysis confirmed the presence of cadherin-5, cadherin-11, DEAD-box protein-23, and pyruvate kinase in the blood of the patient in the study as well as in the blood of four other patients diagnosed with RCC. These results demonstrate the utility of a combined blood/tissue analysis strategy that permits the detection of tumor proteins in the blood of a patient diagnosed with RCC. PMID:20121140

  8. Noninvasive optical quantification of absolute blood flow, blood oxygenation, and oxygen consumption rate in exercising skeletal muscle

    Science.gov (United States)

    Gurley, Katelyn; Shang, Yu; Yu, Guoqiang

    2012-07-01

    This study investigates a method using novel hybrid diffuse optical spectroscopies [near-infrared spectroscopy (NIRS) and diffuse correlation spectroscopy (DCS)] to obtain continuous, noninvasive measurement of absolute blood flow (BF), blood oxygenation, and oxygen consumption rate (\\Vdot O2) in exercising skeletal muscle. Healthy subjects (n=9) performed a handgrip exercise to increase BF and \\Vdot O2 in forearm flexor muscles, while a hybrid optical probe on the skin surface directly monitored oxy-, deoxy-, and total hemoglobin concentrations ([HbO2], [Hb], and THC), tissue oxygen saturation (StO2), relative BF (rBF), and relative oxygen consumption rate (r\\Vdot O2). The rBF and r\\Vdot O2 signals were calibrated with absolute baseline BF and \\Vdot O2 obtained through venous and arterial occlusions, respectively. Known problems with muscle-fiber motion artifacts in optical measurements during exercise were mitigated using a novel gating algorithm that determined muscle contraction status based on control signals from a dynamometer. Results were consistent with previous findings in the literature. This study supports the application of NIRS/DCS technology to quantitatively evaluate hemodynamic and metabolic parameters in exercising skeletal muscle and holds promise for improving diagnosis and treatment evaluation for patients suffering from diseases affecting skeletal muscle and advancing fundamental understanding of muscle and exercise physiology.

  9. In Vivo Photoacoustic Tomography of Total Blood Flow and Potential Imaging of Cancer Angiogenesis and Hypermetabolism

    OpenAIRE

    Yao, Junjie; Maslov, Konstantin I.; Wang, Lihong V.

    2012-01-01

    Blood flow is a key parameter in studying cancer angiogenesis and hypermetabolism. Current photoacoustic blood flow estimation methods focus on either the axial or transverse component of the flow vector. However, the Doppler angle (beam-to-flow angle) is needed to calculate the total flow speed, and it cannot always be estimated accurately in practice, especially when the system's axial and lateral resolutions are different. To overcome this problem, we propose a method to compute the total ...

  10. The use of BDNF to enhance the patency rate of small-diameter tissue-engineered blood vessels through stem cell homing mechanisms.

    Science.gov (United States)

    Zeng, Wen; Wen, Can; Wu, Yangxiao; Li, Li; Zhou, Zhenhua; Mi, Jianhong; Chen, Wen; Yang, Mingcan; Hou, Chunli; Sun, Jiansen; Zhu, Chuhong

    2012-01-01

    The patency rate of small-diameter tissue-engineered blood vessels is the determinant for their application in coronary artery bypass grafting. The coronary artery is innervated by vagus nerves. The origin of vagus nerves is rich in brain-derived neurotrophic factors (BDNF). We have investigated whether BDNF could improve the patency rate of small-diameter tissue-engineered blood vessels through promoting stem cell homing and paracrine activity. In vitro, we isolated early and late endothelial progenitor cells (EPCs) and found BDNF could promote single clone formation and paracrine function of EPCs, and could also induce the proliferation, migration and differentiation of late EPCs. BDNF could enhance the capturing of EPCs in parallel-plate flow chamber. Flow cytometric analysis and laser-scanning confocal microscope showed BDNF could enhance the mobilization and homing of C57BL/6 mouse EPCs after wire injury. Based on it, BDNF was coupled to the lumen surface of the blood vessel matrix material incubated with collagen through SPDP to construct BDNF-modified small-diameter tissue-engineered blood vessel. The blood vessel patency rate was significantly higher than that of control group 8 weeks after implantation in rats and the endothelialization level was superior to control. These results demonstrate that BDNF can effectively improve patency of small-diameter tissue-engineered blood vessels through stem cell homing and paracrine, and it is expected to play an important role in the construction of substitutes for coronary artery bypass grafting.

  11. Iodoamphetamine as a new tracer for local cerebral blood flow in the rat

    DEFF Research Database (Denmark)

    Rapin, J R; Le Poncin-Lafitte, M; Duterte, D;

    1984-01-01

    blood flow and a more real estimation of hippocampal flow. It is concluded from the brain uptake of the derivatives of both amphetamines during the first minutes following their injection that these tracers can be used as a chemical microembolus for the measurement of local cerebral blood flow....

  12. Brain energy metabolism and blood flow differences in healthy aging

    DEFF Research Database (Denmark)

    Aanerud, Joel; Borghammer, Per; Chakravarty, M Mallar;

    2012-01-01

    Cerebral metabolic rate of oxygen consumption (CMRO(2)), cerebral blood flow (CBF), and oxygen extraction fraction (OEF) are important indices of healthy aging of the brain. Although a frequent topic of study, changes of CBF and CMRO(2) during normal aging are still controversial, as some authors...... years. The magnitudes of CMRO(2) and CBF declined in large parts of the cerebral cortex, including association areas, but the primary motor and sensory areas were relatively spared. We found significant increases of OEF in frontal and parietal cortices, excluding primary motor and somatosensory regions......, and in the temporal cortex. Because of the inverse relation between OEF and capillary oxygen tension, increased OEF can compromise oxygen delivery to neurons, with possible perturbation of energy turnover. The results establish a possible mechanism of progression from healthy to unhealthy brain aging, as the regions...

  13. Cerebral blood flow and oxygen metabolism in the Rett syndrome

    Energy Technology Data Exchange (ETDEWEB)

    Yoshikawa, Hideto; Fueki, Noboru; Suzuki, Hisaharu; Sakuragawa, Norio; Iio, Masaaki (National Central Hospital for Mental, Nervous and Muscular Disorders, Tokyo (Japan))

    1992-05-01

    Positron emission tomography (PET) was performed on six patients with the Rett syndrome and the results were compared with the concurrent clinical status of the patients. The cerebral metabolic rate of oxygen (CMRO{sub 2}) was low in five patients, and oxygen extraction fraction (OEF) was low in four patients; both had a tendency to decline with advancing age. Although the cause is unknown, it is suggested that impaired oxidative metabolism exists in the Rett syndrome. An analysis of the distribution among brain regions showed that the ratios of values for the frontal cortex to those for the temporal cortex for both the cerebral blood flow (CBF) and CMRO{sub 2} were lower than those for the controls, which may indicate the loss of of hyperfrontality in the Rett syndrome. Distribution of brain metabolism may be immature in the Rett syndrome. (author).

  14. Peculiarities of Brain's Blood Flow : Role of Carbon Dioxide

    CERN Document Server

    Gersten, Alexander

    2011-01-01

    Among the major factors controlling the cerebral blood flow (CBF), the effect of PaCO2 is peculiar in that it violates autoregulatory CBF mechanisms and allows to explore the full range of the CBF. This research resulted in a simple physical model, with a four parameter formula, relating the CBF to PaCO2. The parameters can be extracted in an easy manner, directly from the experimental data. With this model earlier experimental data sets of Rhesus monkeys and rats were well fitted. Human data were also fitted with this model. Exact formulae were found, which can be used to transform the fits of one animal to the fits of another one. The merit of this transformation is that it enable us the use of rats data as monkeys data simply by rescaling the PaCO2 values and the CBF data. This transformation makes possible the use of experimental animal data instead of human ones.

  15. Portable real time analysis system for regional cerebral blood flow

    International Nuclear Information System (INIS)

    A very portable, regional cerebral blood flow (rCBF) analysis instrument system suitable for use in the operating theater during surgery is under development. Cadmium telluride (CdTe) solid state radiation detectors, an 8086 based data acquisition and communications module and a DEC Microvax computer are used so that the instrument is very compact, yet has the computational power to provide real time data analysis in the clinical environment. The instrument is currently being used at Bowman Gray School of Medicine to study rCBF during cardiopulmonary bypass surgery (CPB). Preliminary studies indicate that monitoring rCBF during this surgical procedure may provide insights into the mechanism that causes a significant fraction of these patients to suffer post operative neuropsychological deficit

  16. Portable real time analysis system for regional cerebral blood flow

    Energy Technology Data Exchange (ETDEWEB)

    Tiernan, T.; Entine, G.; Stump, D.A.; Prough, D.S.

    1988-02-01

    A very portable, regional cerebral blood flow (rCBF) analysis instrument system suitable for use in the operating theater during surgery is under development. Cadmium telluride (CdTe) solid state radiation detectors, an 8086 based data acquisition and communications module and a DEC Microvax computer are used so that the instrument is very compact, yet has the computational power to provide real time data analysis in the clinical environment. The instrument is currently being used at Bowman Gray School of Medicine to study rCBF during cardiopulmonary bypass surgery (CPB). Preliminary studies indicate that monitoring rCBF during this surgical procedure may provide insights into the mechanism that causes a significant fraction of these patients to suffer post operative neuropsychological deficit.

  17. The Utility of Cerebral Blood Flow Assessment in TBI.

    Science.gov (United States)

    Akbik, Omar S; Carlson, Andrew P; Krasberg, Mark; Yonas, Howard

    2016-08-01

    Over the past few decades, intracranial monitoring technologies focused on treating and preempting secondary injury after traumatic brain injury (TBI) have experienced considerable growth. A physiological measure fundamental to the management of these patients is cerebral blood flow (CBF), which may be determined directly or indirectly. Direct measurement has proven difficult previously; however, invasive and non-invasive CBF monitors are now available. This article reviews the history of CBF measurements in TBI as well as the role of CBF in pathologies associated with TBI, such as cerebral autoregulation, hyperemia, and cortical spreading depression. The limitations of various CBF monitors are reviewed in order to better understand their role in TBI management. PMID:27315250

  18. Cerebral blood flow in normal and abnormal sleep and dreaming

    Energy Technology Data Exchange (ETDEWEB)

    Meyer, J.S.; Ishikawa, Y.; Hata, T.; Karacan, I.

    1987-07-01

    Measurements of regional or local cerebral blood flow (CBF) by the xenon-133 inhalation method and stable xenon computerized tomography CBF (CTCBF) method were made during relaxed wakefulness and different stages of REM and non-REM sleep in normal age-matched volunteers, narcoleptics, and sleep apneics. In the awake state, CBF values were reduced in both narcoleptics and sleep apneics in the brainstem and cerebellar regions. During sleep onset, whether REM or stage I-II, CBF values were paradoxically increased in narcoleptics but decreased severely in sleep apneics, while in normal volunteers they became diffusely but more moderately decreased. In REM sleep and dreaming CBF values greatly increased, particularly in right temporo-parietal regions in subjects experiencing both visual and auditory dreaming.

  19. Cerebral blood flow in normal and abnormal sleep and dreaming

    International Nuclear Information System (INIS)

    Measurements of regional or local cerebral blood flow (CBF) by the xenon-133 inhalation method and stable xenon computerized tomography CBF (CTCBF) method were made during relaxed wakefulness and different stages of REM and non-REM sleep in normal age-matched volunteers, narcoleptics, and sleep apneics. In the awake state, CBF values were reduced in both narcoleptics and sleep apneics in the brainstem and cerebellar regions. During sleep onset, whether REM or stage I-II, CBF values were paradoxically increased in narcoleptics but decreased severely in sleep apneics, while in normal volunteers they became diffusely but more moderately decreased. In REM sleep and dreaming CBF values greatly increased, particularly in right temporo-parietal regions in subjects experiencing both visual and auditory dreaming

  20. Cerebral blood flow response to propranolol in streptozotocin diabetic rats

    DEFF Research Database (Denmark)

    Lass, Preben; Knudsen, G M

    1990-01-01

    The influence of propranolol on cerebral blood flow (CBF) was tested in streptozotocin diabetic rats and in control animals. Resting CBF values were 40% lower in the diabetic rats compared with controls. Intravenous injection of propranolol (2 mg kg-1) decreased CBF significantly in the control...... group; the CBF decreased for 15 min after propranolol injection and returned to baseline values after 90 min. In the diabetic rats, the CBF declined steadily but this decrease did not reach significance, even after 90 min. Impaired beta-adrenergic mechanisms may be an important factor in the CBF...... alterations which occur in diabetes mellitus. Further, it is suggested that an impaired CBF response may play a role in CNS lesions in diabetic patients treated with beta antagonists....

  1. Numerical method of characteristics for one-dimensional blood flow

    CERN Document Server

    Acosta, Sebastian; Riviere, Beatrice; Penny, Daniel J; Rusin, Craig G

    2014-01-01

    Mathematical modeling at the level of the full cardiovascular system requires the numerical approximation of solutions to a one-dimensional nonlinear hyperbolic system describing flow in a single vessel. This model is often simulated by computationally intensive methods like finite elements and discontinuous Galerkin, while some recent applications require more efficient approaches (e.g. for real-time clinical decision support, phenomena occurring over multiple cardiac cycles, iterative solutions to optimization/inverse problems, and uncertainty quantification). Further, the high speed of pressure waves in blood vessels greatly restricts the time-step needed for stability in explicit schemes. We address both cost and stability by presenting an efficient and unconditionally stable method for approximating solutions to diagonal nonlinear hyperbolic systems. Theoretical analysis of the algorithm is given along with a comparison of our method to a discontinuous Galerkin implementation. Lastly, we demonstrate the ...

  2. Cerebral blood flow changes in Parkinson's disease associated with dementia

    International Nuclear Information System (INIS)

    Dementia is one of the main non-motor symptoms of Parkinson's disease (PD) and it is diagnosed in about 30% of cases. Its aetiology remains unclear and contributing factors are controversial. Dementia may be more common in old patients with severe motor symptoms and mild cognitive impairment. Clinico-pathological studies show the association between dementia in PD and the age-related group of dementias, such as AD and VaD. A valuable aid in the assessment of dementia in PD is cerebral blood flow (CBF) brain SPECT scanning. It shows three different patterns of rCBF reduction, including frontal lobe hypoperfusion, iu Alzheimer-likel type of hypoperfusion and multiple, vascular defects. The heterogeneity of rCBF reduction may reflect the multifactorial pathophysiology of dementia in PD. It may result from concomitant AD pathology, cerebrovascular disease, destruction of nigro-striato-frontal projection or may be a distinct disease of different aetiology. (author)

  3. Doppler Assessment of Uterine Blood Flow in Recurrent Pregnancy Loss

    Directory of Open Access Journals (Sweden)

    Maryam Barzin

    2011-05-01

    Full Text Available Recurrent spontaneous abortion affects 2%-5% of"ncouples. Uterine perfusion is considered as one of the"nfactors that influences the success of implantation."nDuring the normal menstrual cycle, the impedance"nto uterine artery blood flow diminishes progressively"nduring the luteal phase, reaching the lowest values"nin the period coinciding with the implantation time."nImpedance of uterine arteries is a good indicator of"nthe possibility of a subsequent pregnancy. High blood"nflow resistance is associated with a reduced conception"nrate and women with lower pulsatility index values"nhave the highest possibility of becoming pregnant. An"nimpaired uterine perfusion could play a major role in"nthe pathogenesis of recurrent spontaneous abortion. In"nthis study, we examined sixty women with recurrent"nspontaneous abortion and a control group including"nthirty normal women with at least one previous"nuncomplicated pregnancy and without history of any"nabortion. Transvaginal sonography associated with"nDoppler flow measurement was performed during"nthe midluteal phase of a cycle in all women. The"nmeasurement of the ascending branch of both right"nand left uterine arteries was taken lateral to the cervix"nat the level of the internal os. The pulsatility and"nresistance index of both uterine arteries were calculated"nand compared in both groups. In this presentation we"nreport our finding in two groups. We also explain the"nexact method of study and present some interesting"ncases

  4. Tissue-Informative Mechanism for Wearable Non-invasive Continuous Blood Pressure Monitoring

    Science.gov (United States)

    Woo, Sung Hun; Choi, Yun Young; Kim, Dae Jung; Bien, Franklin; Kim, Jae Joon

    2014-10-01

    Accurate continuous direct measurement of the blood pressure is currently available thru direct invasive methods via intravascular needles, and is mostly limited to use during surgical procedures or in the intensive care unit (ICU). Non-invasive methods that are mostly based on auscultation or cuff oscillometric principles do provide relatively accurate measurement of blood pressure. However, they mostly involve physical inconveniences such as pressure or stress on the human body. Here, we introduce a new non-invasive mechanism of tissue-informative measurement, where an experimental phenomenon called subcutaneous tissue pressure equilibrium is revealed and related for application in detection of absolute blood pressure. A prototype was experimentally verified to provide an absolute blood pressure measurement by wearing a watch-type measurement module that does not cause any discomfort. This work is supposed to contribute remarkably to the advancement of continuous non-invasive mobile devices for 24-7 daily-life ambulatory blood-pressure monitoring.

  5. Multiscale modeling of red blood cell mechanics and blood flow in malaria.

    Directory of Open Access Journals (Sweden)

    Dmitry A Fedosov

    2011-12-01

    Full Text Available Red blood cells (RBCs infected by a Plasmodium parasite in malaria may lose their membrane deformability with a relative membrane stiffening more than ten-fold in comparison with healthy RBCs leading to potential capillary occlusions. Moreover, infected RBCs are able to adhere to other healthy and parasitized cells and to the vascular endothelium resulting in a substantial disruption of normal blood circulation. In the present work, we simulate infected RBCs in malaria using a multiscale RBC model based on the dissipative particle dynamics method, coupling scales at the sub-cellular level with scales at the vessel size. Our objective is to conduct a full validation of the RBC model with a diverse set of experimental data, including temperature dependence, and to identify the limitations of this purely mechanistic model. The simulated elastic deformations of parasitized RBCs match those obtained in optical-tweezers experiments for different stages of intra-erythrocytic parasite development. The rheological properties of RBCs in malaria are compared with those obtained by optical magnetic twisting cytometry and by monitoring membrane fluctuations at room, physiological, and febrile temperatures. We also study the dynamics of infected RBCs in Poiseuille flow in comparison with healthy cells and present validated bulk viscosity predictions of malaria-infected blood for a wide range of parasitemia levels (percentage of infected RBCs with respect to the total number of cells in a unit volume.

  6. Role of cerebral blood flow in extreme breath holding

    Directory of Open Access Journals (Sweden)

    Bain Anthony R.

    2016-01-01

    Full Text Available The role of cerebral blood flow (CBF on a maximal breath-hold (BH in ultra-elite divers was examined. Divers (n = 7 performed one control BH, and one BH following oral administration of the non-selective cyclooxygenase inhibitor indomethacin (1.2 mg/kg. Arterial blood gases and CBF were measured prior to (baseline, and at BH termination. Compared to control, indomethacin reduced baseline CBF and cerebral delivery of oxygen (CDO2 by about 26% (p < 0.01. Indomethacin reduced maximal BH time from 339 ± 51 to 319 ± 57 seconds (p = 0.04. In both conditions, the CDO2 remained unchanged from baseline to the termination of apnea. At BH termination, arterial oxygen tension was higher following oral administration of indomethacin compared to control (4.05 ± 0.45 vs. 3.44 ± 0.32 kPa. The absolute increase in CBF from baseline to the termination of apnea was lower with indomethacin (p = 0.01. These findings indicate that the impact of CBF on maximal BH time is likely attributable to its influence on cerebral H+ washout, and therefore central chemoreceptive drive to breathe, rather than to CDO2.

  7. Lipiodol-TAE and hepatic blood flow in radiation hepatitis

    Energy Technology Data Exchange (ETDEWEB)

    Azuma, Kazuyoshi; Hirokawa, Yutaka; Fukuoka, Haruhito (Hiroshima Univ. (Japan). School of Medicine) (and others)

    1991-06-01

    A 58-year-old man with biliary tract cancer associated with obstructive jaundice was treated with radiation therapy. The area encompassing the common bile duct and the porta hepatis was irradiated with 2 Gy per fraction to a total dose of 40 Gy. One day after the completion of irradiation, Lipiodol-transcatheter arterial embolization (Lipiodol-TAE) was performed. The irradiated field was seen as contrast media accumulation on hepatic arteriography and as defect shadow on superior mesenteric arteriography. Retention of Lipiodol, injected from the hepatic artery, was not seen in the irradiated field. Hepatic parenchyma exposed to irradiation was shown as low density area on CT performed 28 days after Lipiodol-TAE. The irradiated field was gradually enhanced on serial CT scans, and was seen as high density area on delayed scans. These radiologic appearances lead to the diagnosis of radiation hepatitis in this patient. A review of the literature, in addition to these findings, revealed that sinusoid blood flow in radiation hepatitis is delayed, depending on arterial blood, and that peribiliary plexus is strongly involved in hemodynamics of arterially injected Lipiodol. (N.K.).

  8. Dual role of cerebral blood flow in regional brain temperature control in the healthy newborn infant.

    Science.gov (United States)

    Iwata, Sachiko; Tachtsidis, Ilias; Takashima, Sachio; Matsuishi, Toyojiro; Robertson, Nicola J; Iwata, Osuke

    2014-10-01

    Small shifts in brain temperature after hypoxia-ischaemia affect cell viability. The main determinants of brain temperature are cerebral metabolism, which contributes to local heat production, and brain perfusion, which removes heat. However, few studies have addressed the effect of cerebral metabolism and perfusion on regional brain temperature in human neonates because of the lack of non-invasive cot-side monitors. This study aimed (i) to determine non-invasive monitoring tools of cerebral metabolism and perfusion by combining near-infrared spectroscopy and echocardiography, and (ii) to investigate the dependence of brain temperature on cerebral metabolism and perfusion in unsedated newborn infants. Thirty-two healthy newborn infants were recruited. They were studied with cerebral near-infrared spectroscopy, echocardiography, and a zero-heat flux tissue thermometer. A surrogate of cerebral blood flow (CBF) was measured using superior vena cava flow adjusted for cerebral volume (rSVC flow). The tissue oxygenation index, fractional oxygen extraction (FOE), and the cerebral metabolic rate of oxygen relative to rSVC flow (CMRO₂ index) were also estimated. A greater rSVC flow was positively associated with higher brain temperatures, particularly for superficial structures. The CMRO₂ index and rSVC flow were positively coupled. However, brain temperature was independent of FOE and the CMRO₂ index. A cooler ambient temperature was associated with a greater temperature gradient between the scalp surface and the body core. Cerebral oxygen metabolism and perfusion were monitored in newborn infants without using tracers. In these healthy newborn infants, cerebral perfusion and ambient temperature were significant independent variables of brain temperature. CBF has primarily been associated with heat removal from the brain. However, our results suggest that CBF is likely to deliver heat specifically to the superficial brain. Further studies are required to assess the

  9. Regional blood flow and skeletal muscle energy status in endotoxemic rats

    International Nuclear Information System (INIS)

    Endotoxins induce muscle wasting in part as a result of depressed protein synthesis. To investigate whether these changes reflect impaired energy transduction, blood flow, O2 extraction, and high-energy phosphates in muscle and whole-body O2 consumption (Vo2) have been measured. Vo2 was measured for 6 h after an initial sublethal dose of endotoxin (Escherichia coli lipopolysaccharide 0.3 mg/100 g body wt sc) or saline and during 6 h after a second dose 24 h later. In fed or fasted rats, Vo2 was either increased or better maintained after endotoxin. In anesthetized fed rats 3-4 h after the second dose of endotoxin Vo2 was increased, and this was accompanied by increased blood flow measured by 57Co-labelled microspheres to liver (hepatic arterial supply), kidney, and perirenal brown adipose tissue and a 57 and 64% decrease in flow to back and hindlimb muscle, respectively, with no change in any other organ. Hindlimb arteriovenous O2 was unchanged, indicating markedly decreased aerobic metabolism in muscle, and the contribution of the hindlimb to whole-body Vo2 decreased by 46%. Adenosine 5'-triphosphate levels in muscle were unchanged in endotoxin-treated rats, and this was confirmed by topical nuclear magnetic resonance spectroscopy, which also showed muscle pH to be unchanged. These results show that, although there is decreased blood flow and aerobic oxidation in muscle, adenosine 5'-triphosphate availability does not appear to be compromised so that the endotoxin-induced muscle catabolism and decreased protein synthesis must reflex some other mechanism

  10. Effects of lornoxicam and intravenous ibuprofen on erythrocyte deformability and hepatic and renal blood flow in rats

    Science.gov (United States)

    Arpacı, Hande; Çomu, Faruk Metin; Küçük, Ayşegül; Kösem, Bahadır; Kartal, Seyfi; Şıvgın, Volkan; Turgut, Hüseyin Cihad; Aydın, Muhammed Enes; Koç, Derya Sebile; Arslan, Mustafa

    2016-01-01

    Background Change in blood supply is held responsible for anesthesia-related abnormal tissue and organ perfusion. Decreased erythrocyte deformability and increased aggregation may be detected after surgery performed under general anesthesia. It was shown that nonsteroidal anti-inflammatory drugs decrease erythrocyte deformability. Lornoxicam and/or intravenous (iv) ibuprofen are commonly preferred analgesic agents for postoperative pain management. In this study, we aimed to investigate the effects of lornoxicam (2 mg/kg, iv) and ibuprofen (30 mg/kg, iv) on erythrocyte deformability, as well as hepatic and renal blood flows, in male rats. Methods Eighteen male Wistar albino rats were randomly divided into three groups as follows: iv lornoxicam-treated group (Group L), iv ibuprofen-treated group (Group İ), and control group (Group C). Drug administration was carried out by the iv route in all groups except Group C. Hepatic and renal blood flows were studied by laser Doppler, and euthanasia was performed via intra-abdominal blood uptake. Erythrocyte deformability was measured using a constant-flow filtrometry system. Results Lornoxicam and ibuprofen increased the relative resistance, which is an indicator of erythrocyte deformability, of rats (P=0.016). Comparison of the results from Group L and Group I revealed no statistically significant differences (P=0.694), although the erythrocyte deformability levels in Group L and Group I were statistically higher than the results observed in Group C (P=0.018 and P=0.008, respectively). Hepatic and renal blood flows were significantly lower than the same in Group C. Conclusion We believe that lornoxicam and ibuprofen may lead to functional disorders related to renal and liver tissue perfusion secondary to both decreased blood flow and erythrocyte deformability. Further studies regarding these issues are thought to be essential. PMID:27536068

  11. Self-propelled particles that transport cargo through flowing blood and halt hemorrhage.

    Science.gov (United States)

    Baylis, James R; Yeon, Ju Hun; Thomson, Max H; Kazerooni, Amir; Wang, Xu; St John, Alex E; Lim, Esther B; Chien, Diana; Lee, Anna; Zhang, Jesse Q; Piret, James M; Machan, Lindsay S; Burke, Thomas F; White, Nathan J; Kastrup, Christian J

    2015-10-01

    Delivering therapeutics deep into damaged tissue during bleeding is challenging because of the outward flow of blood. When coagulants cannot reach and clot blood at its source, uncontrolled bleeding can occur and increase surgical complications and fatalities. Self-propelling particles have been proposed as a strategy for transporting agents upstream through blood. Many nanoparticle and microparticle systems exhibiting autonomous or collective movement have been developed, but propulsion has not been used successfully in blood or used in vivo to transport therapeutics. We show that simple gas-generating microparticles consisting of carbonate and tranexamic acid traveled through aqueous solutions at velocities of up to 1.5 cm/s and delivered therapeutics millimeters into the vasculature of wounds. The particles transported themselves through a combination of lateral propulsion, buoyant rise, and convection. When loaded with active thrombin, these particles worked effectively as a hemostatic agent and halted severe hemorrhage in multiple animal models of intraoperative and traumatic bleeding. Many medical applications have been suggested for self-propelling particles, and the findings of this study show that the active self-fueled transport of particles can function in vivo to enhance drug delivery. PMID:26601282

  12. The blood flow changes associated with idiopathic and secondary intracranial hypertension

    International Nuclear Information System (INIS)

    Full text: The radiological diagnosis of idiopathic intracranial hypertension (IIH) is one of exclusion and as the MR venogram is prone to flow artefacts, the diagnosis of secondary intracranial hypertension (SIH) can also be problematic. The purpose of this paper is to define the blood flow characteristics, which are useful in the diagnosis of these conditions. Twelve patients with clinical findings suggestive of IIH and 12 control subjects were investigated with MR venography and MR flow quantification studies of the cerebral arteries and veins. Total cerebral blood flow, superior sagittal sinus (SSS) and straight sinus (ST) blood flows were measured. MR venography confirmed 7 of the 12 patients had venous outflow obstruction and thus SIH. The remaining 5 patients had IIH. The control patients mean total blood flow was 855 ml/min, the SSS flow was 400ml/min and the ST flow 117 ml/min. The total blood flow in the IIH patients was 46% higher (P = 0.0002) and the ST blood flow 38% higher (P = 0.05) than the control group, the SSS flow was 17% higher but this failed to reach significance. In SIH the SSS flow was reduced by 25% (P = 0.003) compared with the control group, the total and ST blood flow were not significantly altered. In IIH there is hyperaemia and the SSS appears limited in its ability to increase flow, therefore venous collaterals carry a greater load. In SIH, selective obstruction of the SSS reduces flow in this vessel but total blood flow is normal indicating there is also increased flow in collateral veins. Presumably the limited ability of the SSS to drain blood away from the brain in each condition raises venous sinus pressure and alters CSF resorption giving raised CSF pressure. Copyright (2002) Blackwell Science Pty Ltd

  13. Skeletal blood flow in Paget's disease of bone and its response to calcitonin therapy.

    Science.gov (United States)

    Wootton, R; Reeve, J; Spellacy, E; Tellez-Yudilevich, M

    1978-01-01

    1. Blood flow to the skeleton was measured by the 18F clearance method of Wooton, Reeve & Veall (1976) in 24 patients with untreated Paget's disease. In every patient but one, resting skeletal blood flow was increased. There was a significant positive correlation between skeletal blood flow and serum alkaline phosphatase and between skeletal blood flow and urinary total hydroxyproline excretion. 2. Fourteen patients were re-studied after they had received short-term (7 days or less) or long-term (7 weeks or more) calcitonin. Skeletal blood flow, alkaline phosphatase and urinary hydroxy-proline excretion fell towards normal in every case. There was some evidence from the short-term studies that calcitonin produced a more rapid fall in skeletal blood flow than in alkaline phosphatase. 3. Glomerular filtration rate appeared to increase transiently in response to calcitonin.

  14. Placental blood flow measurements with radioisotopes in the pregnant guinea pig

    International Nuclear Information System (INIS)

    In 15 pregnant guinea pigs near term the blood flow (BF) of the myometrium and the placenta as well as the cardiac output were measured with 99Tcsup(m)-labelled microspheres. In front of one placenta the clearance of 133Xe was estimated in the same animal. For the 133Xe measurement a theoretical concept is presented. The mean placental BF is 105ml/(minx100g)(SD:84) for 99Tcsup(m) and 244(SD:80)ml/(minx100g) for 133Xe. The difference in both flow values is assumed to be related to foetal placental BF. The placental blood flow is also related to the location of the placenta in the uterine horn. The ratio of myometrial blood flow to placental blood flow decreased with an increase in the mean arterial blood pressure. The measurements are a preliminary report of an attempt to compare two different methods in measuring placental blood flow. (author)

  15. Subcutaneous blood flow in man during sleep with continous epdural anaesthesia

    DEFF Research Database (Denmark)

    Sindrup, JH; Petersen, Lars Jelstrup; Kastrup, Jens;

    1996-01-01

    BACKGROUND: Subcutaneous blood flow increases during sleep and we evaluated if this increase is affected by epidural anaesthesia. METHODS: Lower leg subcutaneous blood flow was determined by 133Xenon clearance in ten subjects during continous epidural anaesthesia at L2-L3 including eight hours...... of sleep, while the opper abdominal subcutaneous blood flow served as control. RESULTS: Epidural anaesthesia to the level of the umbilicus was followed by an increase in the lower leg subcutaneous blood flow fra 3.4 (1.8-6.3) to 7.8 (3.6-16.9) ml min-1 (median and range; P...-1 100 g-1 after 34 (29-70) min (Pepidural anaesthesia induced only a temporary increase in lower leg subcutaneous blood flow, it hindered the rise in subcutaneous blood flow normally manifest...

  16. LASER-DOPPLER VELOCIMETRY AND MONTE-CARLO SIMULATIONS ON MODELS FOR BLOOD PERFUSION IN TISSUE

    NARCIS (Netherlands)

    DEMUL, FFM; KOELINK, MH; KOK, ML; HARMSMA, PJ; GREVE, J; GRAAFF, R; AARNOUDSE, JG

    1995-01-01

    Laser Doppler flow measurements and Monte Carlo simulations on small blood perfusion flow models at 780 nm are presented and compared. The dimensions of the optical sample volume are investigated as functions of the distance of the laser to the detector and as functions of the angle of penetration o

  17. A Model of Anterograde Oxygenated Lung Blood Flow in Acardia.

    Science.gov (United States)

    Marinakis, Sotirios; Burki, Marco; Abdel-Sayed, Saad; von Segesser, Ludwig Karl

    2016-01-01

    In extreme situations such as hyperacute rejection of heart transplant or major heart trauma, heart explantation and extracorporeal membrane oxygenation (ECMO) hemodynamic support might be the only means for survival. In our previous model of acardia, pulmonary artery (PA) was clamped and did not receive any anterograde blood flow. A model of anterograde PA perfusion might be necessary to avoid ischemic pulmonary damage in prolonged ECMO in acardia. The aim of this study was to describe the surgical technique and to determine the feasibility of an anterograde lung perfusion in acardia through the anastomosis of the right internal mammary artery (RIMA) to the PA. A venoarterial cardiopulmonary bypass was established in three pigs (72 ± 2.6 kg) by the transjugular insertion to the caval axis of a double-staged cannula with carotid artery return. Heart was excised and ECMO was established as previously reported. Right internal mammary artery was harvested and after measurement of its output (93.3 ± 5.8 ml/min, representing 2.17% ± 0.15% of total pump flow), it was anastomosed to PA. Right internal mammary artery anastomosis to PA is a feasible, safe, and easy to perform maneuver assuring an anterograde lung perfusion in acardia. PMID:27442854

  18. Physiological non-Newtonian blood flow through single stenosed artery

    Science.gov (United States)

    Mamun, Khairuzzaman; Rahman, Mohammad Matiur; Akhter, Most. Nasrin; Ali, Mohammad

    2016-07-01

    A numerical simulation to investigate the Non-Newtonian modelling effects on physiological flows in a three dimensional idealized artery with a single stenosis of 85% severity. The wall vessel is considered to be rigid. Oscillatory physiological and parabolic velocity profile has been imposed for inlet boundary condition. Where the physiological waveform is performed using a Fourier series with sixteen harmonics. The investigation has a Reynolds number range of 96 to 800. Low Reynolds number k - ω model is used as governing equation. The investigation has been carried out to characterize two Non-Newtonian constitutive equations of blood, namely, (i) Carreau and (ii) Cross models. The Newtonian model has also been investigated to study the physics of fluid. The results of Newtonian model are compared with the Non-Newtonian models. The numerical results are presented in terms of pressure, wall shear stress distributions and the streamlines contours. At early systole pressure differences between Newtonian and Non-Newtonian models are observed at pre-stenotic, throat and immediately after throat regions. In the case of wall shear stress, some differences between Newtonian and Non-Newtonian models are observed when the flows are minimum such as at early systole or diastole.

  19. Regulation of peripheral blood flow in Complex Regional Pain Syndrome: clinical implication for symptomatic relief and pain management

    Directory of Open Access Journals (Sweden)

    Coderre Terence J

    2009-09-01

    Full Text Available Abstract Background During the chronic stage of Complex Regional Pain Syndrome (CRPS, impaired microcirculation is related to increased vasoconstriction, tissue hypoxia, and metabolic tissue acidosis in the affected limb. Several mechanisms may be responsible for the ischemia and pain in chronic cold CPRS. Discussion The diminished blood flow may be caused by either sympathetic dysfunction, hypersensitivity to circulating catecholamines, or endothelial dysfunction. The pain may be of neuropathic, inflammatory, nociceptive, or functional nature, or of mixed origin. Summary The origin of the pain should be the basis of the symptomatic therapy. Since the difference in temperature between both hands fluctuates over time in cold CRPS, when in doubt, the clinician should prioritize the patient's report of a persistent cold extremity over clinical tests that show no difference. Future research should focus on developing easily applied methods for clinical use to differentiate between central and peripheral blood flow regulation disorders in individual patients.

  20. Synchronization of Sacral Skin Blood Flow Oscillations in Response to Local Heating

    OpenAIRE

    Jan, Yih-Kuen; Liao, Fuyuan

    2011-01-01

    Local heating causes an increase in skin blood flow by activating sensory axon reflex and metabolic nitric oxide controls. It has been observed that the remote skin area without temperature changes also shows a slightly increase in blood flow. The responsible mechanism of this indirect vasodilation remains unclear. We hypothesized that the remote skin area will have enhanced synchronization of blood flow oscillations (BFO), thus inducing a vasodilatory response. We studied BFO in two sites se...

  1. Extraction of the magnetohydrodynamic blood flow potential from the surface electrocardiogram in magnetic resonance imaging.

    Science.gov (United States)

    Nijm, Grace M; Swiryn, Steven; Larson, Andrew C; Sahakian, Alan V

    2008-07-01

    The magnetohydrodynamic effect generates voltages related to blood flow, which are superimposed on the electrocardiogram (ECG) used for gating during cardiac magnetic resonance imaging (MRI). A method is presented for extracting the magnetohydrodynamic signal from the ECG. The extracted magnetohydrodynamic blood flow potential may be physiologically meaningful due to its relationship to blood flow. Removal of the magnetohydrodynamic voltages from the ECG can potentially lead to improved gating and diagnostically useful ECGs.

  2. Myocardial Ischemia: Lack of Coronary Blood Flow or Myocardial Oxygen Supply/Demand Imbalance?

    Science.gov (United States)

    Heusch, Gerd

    2016-07-01

    Regional myocardial blood flow and contractile function in ischemic myocardium are well matched, and there is no evidence for an oxygen supply/demand imbalance. Thus, myocardial ischemia is lack of coronary blood flow with electric, functional, metabolic, and structural consequences for the myocardium. All therapeutic interventions must aim to improve blood flow to ischemic myocardium as much and as quickly as possible. PMID:27390331

  3. Low resource processing algorithms for laser Doppler blood flow imaging.

    Science.gov (United States)

    Nguyen, Hoang C; Hayes-Gill, Barrie R; Zhu, Yiqun; Crowe, John A; He, Diwei; Morgan, Stephen P

    2011-07-01

    The emergence of full field laser Doppler blood flow imaging systems based on CMOS camera technology means that a large amount of data from each pixel in the image needs to be processed rapidly and system resources need to be used efficiently. Conventional processing algorithms that are utilized in single point or scanning systems are therefore not an ideal solution as they will consume too much system resource. Two processing algorithms that address this problem are described and efficiently implemented in a field programmable gate array. The algorithms are simple enough to use low system resource but effective enough to produce accurate flow measurements. This enables the processing unit to be integrated entirely in an embedded system, such as in an application-specific integrated circuit. The first algorithm uses a short Fourier transformation length (typically 8) but averages the output multiple times (typically 128). The second method utilizes an infinite impulse response filter with a low number of filter coefficients that operates in the time domain and has a frequency-weighted response. The algorithms compare favorably with the reference standard 1024 point fast Fourier transform in terms of both resource usage and accuracy. The number of data words per pixel that need to be stored for the algorithms is 1024 for the reference standard, 8 for the short length Fourier transform algorithm and 5 for the algorithm based on the infinite impulse response filter. Compared to the reference standard the error in the flow calculation is 1.3% for the short length Fourier transform algorithm and 0.7% for the algorithm based on the infinite impulse response filter. PMID:21316289

  4. BIFURCATION OF FLOW AND MASS TRANSPORT IN A CURVED BLOOD VESSEL

    Institute of Scientific and Technical Information of China (English)

    TAN Wenchang(谭文长); WEI Lan(魏兰); ZHAO Yaohua(赵耀华); TAKASHI Masuoka

    2003-01-01

    A numerical analysis of flow and concentration fields of macromolecules in a slightly curved blood vessel was carried out. Based on these results, the effect of the bifurcation of a flow on the mass transport in a curved blood vessel was discussed. The macromolecules turned out to be easier to deposit in the inner part of the curved blood vessel near the critical Dean number. Once the Dean number is higher than the critical number, the bifurcation of the flow appears. This bifurcation can prevent macromolecules from concentrating in the inner part of the curved blood vessel. This result is helpful for understanding the possible correlations between the blood dynamics and atherosclerosis.

  5. Time-resolved volumetric MRI blood flow: a Doppler ultrasound perspective

    Science.gov (United States)

    van Pelt, Roy; Oliván Bescós, Javier; Nagel, Eike; Vilanova, Anna

    2014-03-01

    Hemodynamic information is increasingly inspected to assess cardiovascular disease. Abnormal blood-flow patterns include high-speed jet flow and regurgitant flow. Such pathological blood-flow patterns are nowadays mostly inspected by means of color Doppler ultrasound imaging. To date, Doppler ultrasound has been the prevailing modality for blood-flow analysis, providing non-invasive and cost-effective blood-flow imaging. Since recent years, magnetic resonance imaging (MRI) is increasingly employed to measure time-resolved blood-flow data. Albeit more expensive, MRI enables volumetric velocity encoding, providing true vector-valued data with less noise. Domain experts in the field of ultrasound and MRI have extensive experience in the interpretation of blood-flow information, although they employ different analysis techniques. We devise a visualization framework that extends on common Doppler ultrasound visualizations, exploiting the added value of MRI velocity data, and aiming for synergy between the domain experts. Our framework enables experts to explore the advantages and disadvantages of the current renditions of their imaging data. Furthermore, it facilitates the transition from conventional Doppler ultrasound images to present-day high-dimensional velocity fields. To this end, we present a virtual probe that enables direct exploration of MRI-acquired blood-flow velocity data using user-friendly interactions. Based on the probe, Doppler ultrasound inspired visualizations convey both in-plane and through-plane blood-flow velocities. In a compound view, these two-dimensional visualizations are linked to state-of-the-art three-dimensional blood-flow visualizations. Additionally, we introduce a novel volume rendering of the blood-flow velocity data that emphasizes anomalous blood-flow patterns. The visualization framework was evaluated by domain experts, and we present their feedback.

  6. Eigenspectra optoacoustic tomography achieves quantitative blood oxygenation imaging deep in tissues

    CERN Document Server

    Tzoumas, Stratis; Olefir, Ivan; Stangl, Stefan; Symvoulidis, Panagiotis; Glasl, Sarah; Bayer, Christine; Multhoff, Gabriele; Ntziachristos, Vasilis

    2015-01-01

    Light propagating in tissue attains a spectrum that varies with location due to wavelength-dependent fluence attenuation by tissue optical properties, an effect that causes spectral corruption. Predictions of the spectral variations of light fluence in tissue are challenging since the spatial distribution of optical properties in tissue cannot be resolved in high resolution or with high accuracy by current methods. Spectral corruption has fundamentally limited the quantification accuracy of optical and optoacoustic methods and impeded the long sought-after goal of imaging blood oxygen saturation (sO2) deep in tissues; a critical but still unattainable target for the assessment of oxygenation in physiological processes and disease. We discover a new principle underlying light fluence in tissues, which describes the wavelength dependence of light fluence as an affine function of a few reference base spectra, independently of the specific distribution of tissue optical properties. This finding enables the introd...

  7. Mathematical analysis of non-Newtonian blood flow in stenosis narrow arteries.

    Science.gov (United States)

    Sriyab, Somchai

    2014-01-01

    The flow of blood in narrow arteries with bell-shaped mild stenosis is investigated that treats blood as non-Newtonian fluid by using the K-L model. When skin friction and resistance of blood flow are normalized with respect to non-Newtonian blood in normal artery, the results present the effect of stenosis length. When skin friction and resistance of blood flow are normalized with respect to Newtonian blood in stenosis artery, the results present the effect of non-Newtonian blood. The effect of stenosis length and effect of non-Newtonian fluid on skin friction are consistent with the Casson model in which the skin friction increases with the increase of either stenosis length or the yield stress but the skin friction decreases with the increase of plasma viscosity coefficient. The effect of stenosis length and effect of non-Newtonian fluid on resistance of blood flow are contradictory. The resistance of blood flow (when normalized by non-Newtonian blood in normal artery) increases when either the plasma viscosity coefficient or the yield stress increases, but it decreases with the increase of stenosis length. The resistance of blood flow (when normalized by Newtonian blood in stenosis artery) decreases when either the plasma viscosity coefficient or the yield stress increases, but it decreases with the increase of stenosis length.

  8. MEASUREMENT OF REGIONAL BONE BLOOD FLOW IN THE CANINE MANDIBULAR RAMUS USING RADIOLABELLED TOAD RED BLOOD CELLS

    Institute of Scientific and Technical Information of China (English)

    毛驰; 王翰章

    1994-01-01

    Toad red blood cells were used to measure regional bone blood flow in the canine mandibular ramus.The blood cells were labelled with sodium pertechnetate and fixed in 10% formalin;they were 22×15 μm in size and had a specific gravity close to that of dog red blood cells.These cells had no discernible effect on systemic hemody-namics after injection,did not agglutinate,were well mixed and evenly distributed throughout the body,and were completely extracted in one circulation through the mandible.The mandibular ramus was divided into six regions,and the blood flow rates in each were found to be similar to those reported in previous studies with radiolabelled carbonized,microspheres.Furthermore,the blood flow distribution pattern of the mandibular ramus determined in this study was identical to that of our previous study using the bone-seeking radionuclide method.We suggest that radiolabelled toad red blood cells are an ideal marker for measuring regional blood flow in the canine mandible.

  9. Determination of the amplitude and phase relationships between oscillations in skin temperature and photoplethysmography-measured blood flow in fingertips

    International Nuclear Information System (INIS)

    It is well established that skin temperature oscillations in fingertips coexist with blood flow oscillations and there is a certain correlation between them. At the same time, the reasons for differences in waveform and the delay between the blood flow and temperature oscillations are far from being fully understood. In this study we determine the relationships between spectral components of the blood flow and temperature oscillations in fingertips, and we ascertain the frequency dependences of amplitude attenuation and delay time for the temperature oscillations. The blood flow oscillations were considered as a source of thermal waves propagating from micro-vessels towards the skin surface and manifesting as temperature oscillations. The finger temperature was measured by infrared thermography and blood flow was assessed by photoplethysmography for ten healthy subjects. The time–frequency analysis of oscillations was based on the Morlet wavelet transform. The frequency dependences of delay time and amplitude attenuation in temperature compared with blood flow oscillations have been determined in endothelial (0.005–0.02 Hz) and neurogenic (0.02–0.05 Hz) frequency bands using the wavelet spectra. We approximated the experimental frequency dependences by equations describing thermal wave propagation through the medium and taking into account the thermal properties and thickness of a tissue. Results of analysis show that with the increase of frequency f the delay time of temperature oscillations decreases inversely proportional to f1/2, and the attenuation of the amplitude increases directly proportional to exp f1/2. Using these relationships allows us to increase correlation between the processed temperature oscillations and blood flow oscillations from 0.2 to 0.7 within the frequency interval 0.005–0.05 Hz. The established experimental and theoretical relationships clarify an understanding of interrelation between the dynamics of blood flow and skin

  10. Decreased cerebral blood flow after administration of sodium bicarbonate in the distressed newborn infant

    DEFF Research Database (Denmark)

    Lou, H C; Lassen, N A; Fris-Hansen, B

    1978-01-01

    In the course of our studies on cerebral blood flow in newborn infants, we have observed a striking depressing effect of sodium bicarbonate infusion on cerebral blood flow which in some cases may severely aggravate cerebral ischemia. We measured cerebral blood flow before and after the treatment...... with 1 to 8 meqs of sodium bicarbonate in seven distressed newborn infants. The 133 Xe clearance technique was used. The results showed in six of the seven cases a decrease in cerebral blood flow, which in most cases was reduced to 14 to 22 ml/100 g/min, which is about half the value prior to the...

  11. Modeling cerebral blood flow during posture change from sitting to standing

    DEFF Research Database (Denmark)

    Ottesen, Johnny T.; Olufsen, M.; Tran, H.T.

    2004-01-01

    extremities, the brain, and the heart. We use physiologically based control mechanisms to describe the regulation of cerebral blood flow velocity and arterial pressure in response to orthostatic hypotension resulting from postural change. To justify the fidelity of our mathematical model and control......Abstract Hypertension, decreased cerebral blood flow, and diminished cerebral blood flow velocity regulation, are among the first signs indicating the presence of cerebral vascular disease. In this paper, we will present a mathematical model that can predict blood flow and pressure during posture...

  12. Visualization of microvascular blood flow in mouse kidney and spleen by quantum dot injection with "in vivo cryotechnique".

    Science.gov (United States)

    Terada, Nobuo; Saitoh, Yurika; Saitoh, Sei; Ohno, Nobuhiko; Jin, Takashi; Ohno, Shinichi

    2010-12-01

    The "in vivo cryotechnique" (IVCT) is a powerful tool to instantly capture blood flow, and all plasma components are well kept in tissue samples. In this study, we injected glutathione (GSH)-coated quantum dots (QDs), which emit a 650-nm-fluorescent signal with an ultraviolet excitation, into anesthetized mouse left ventricles, and IVCT was performed for kidneys, spleens and livers at 2, 5, 10, 15, 30s or 24h after the QD injection. The frozen tissues were processed to freeze-substitution fixation (FS). Then, some specimens were embedded in paraffin wax for tissue sectioning, and some were cut with a razor blade and directly mounted on glass slides. They were observed in fluorescence or confocal laser scanning microscope (CLSM). In the renal cortex, QD distribution was detected mostly in glomerular blood capillaries at 2second, and extended to peritubular blood capillaries at 5s. Distribution of horseradish peroxidase (HRP) in renal cortex at 30s after the injection was compared by the simultaneous injection with QDs. HRP was detected by a diaminobenzidin reaction in interstitium in addition to blood vessels, whereas QDs were localized only inside blood vessels. Three-dimensional reconstruction with CLSM demonstrated the capillary networks in the whole renal glomerulus. In the spleens, QDs were detected in splenic cords entering from sheathed capillaries at 10s, and extended to deeper splenic cords and also into splenic sinuses at 15s. Thus, strict time-dependent visualization of blood flow in tissue sections became possible within seconds by the new technical combination of IVCT and injection of QDs into animal organs. PMID:20858507

  13. Modeling of Cerebral Oxygen Transport Based on In vivo Microscopic Imaging of Microvascular Network Structure, Blood Flow, and Oxygenation.

    Science.gov (United States)

    Gagnon, Louis; Smith, Amy F; Boas, David A; Devor, Anna; Secomb, Timothy W; Sakadžić, Sava

    2016-01-01

    Oxygen is delivered to brain tissue by a dense network of microvessels, which actively control cerebral blood flow (CBF) through vasodilation and contraction in response to changing levels of neural activity. Understanding these network-level processes is immediately relevant for (1) interpretation of functional Magnetic Resonance Imaging (fMRI) signals, and (2) investigation of neurological diseases in which a deterioration of neurovascular and neuro-metabolic physiology contributes to motor and cognitive decline. Experimental data on the structure, flow and oxygen levels of microvascular networks are needed, together with theoretical methods to integrate this information and predict physiologically relevant properties that are not directly measurable. Recent progress in optical imaging technologies for high-resolution in vivo measurement of the cerebral microvascular architecture, blood flow, and oxygenation enables construction of detailed computational models of cerebral hemodynamics and oxygen transport based on realistic three-dimensional microvascular networks. In this article, we review state-of-the-art optical microscopy technologies for quantitative in vivo imaging of cerebral microvascular structure, blood flow and oxygenation, and theoretical methods that utilize such data to generate spatially resolved models for blood flow and oxygen transport. These "bottom-up" models are essential for the understanding of the processes governing brain oxygenation in normal and disease states and for eventual translation of the lessons learned from animal studies to humans. PMID:27630556

  14. Modeling of Cerebral Oxygen Transport Based on In vivo Microscopic Imaging of Microvascular Network Structure, Blood Flow, and Oxygenation

    Science.gov (United States)

    Gagnon, Louis; Smith, Amy F.; Boas, David A.; Devor, Anna; Secomb, Timothy W.; Sakadžić, Sava

    2016-01-01

    Oxygen is delivered to brain tissue by a dense network of microvessels, which actively control cerebral blood flow (CBF) through vasodilation and contraction in response to changing levels of neural activity. Understanding these network-level processes is immediately relevant for (1) interpretation of functional Magnetic Resonance Imaging (fMRI) signals, and (2) investigation of neurological diseases in which a deterioration of neurovascular and neuro-metabolic physiology contributes to motor and cognitive decline. Experimental data on the structure, flow and oxygen levels of microvascular networks are needed, together with theoretical methods to integrate this information and predict physiologically relevant properties that are not directly measurable. Recent progress in optical imaging technologies for high-resolution in vivo measurement of the cerebral microvascular architecture, blood flow, and oxygenation enables construction of detailed computational models of cerebral hemodynamics and oxygen transport based on realistic three-dimensional microvascular networks. In this article, we review state-of-the-art optical microscopy technologies for quantitative in vivo imaging of cerebral microvascular structure, blood flow and oxygenation, and theoretical methods that utilize such data to generate spatially resolved models for blood flow and oxygen transport. These “bottom-up” models are essential for the understanding of the processes governing brain oxygenation in normal and disease states and for eventual translation of the lessons learned from animal studies to humans.

  15. A NUMERICAL ANALYSIS OF THE BLOOD FLOW AROUND THE BILEAFLET MECHANICAL HEART VALVES WITH DIFFERENT ROTATIONAL IMPLANTATION ANGLES

    Institute of Scientific and Technical Information of China (English)

    HONG Taehyup; KIM Chang Nyung

    2011-01-01

    The effects of implantation angles of Bileaflet Mechanical Heart Valves (BMHVs) on the blood flow and the leaflet motion are investigated in this paper.The physiological blood flow interacting with the moving leaflets ofa BMHV is simulated with a strongly coupled implicit Fluid-Structure Interaction (FSI) method based on the Arbitrary-Lagrangian-Eulerian (ALE) approach and the dynamic mesh method (remeshing) in Fluent.BMHVs are widely used to be implanted to replace the diseascd heart valves,but the patients would suffer from some complications such as hemolysis,platelet activation,tissue overgrowth and device failure.These complications are closely related to both the flow characteristics near the valves and the leaflet dynamics.The currentnumerical model is validated against a previous experimental study.The numerical results show that as the rotation angle of BMHV is increased the degree of asymmetry of the blood flow and the leaflet motion is increased,which may lead to an unbalanced force acting on the BMHVs.This study shows the applicability of the FSI model for the interaction between the blood flow and the leaflet motion in BMHVs.

  16. Cerebral blood flow in Alzheimer’s disease

    Directory of Open Access Journals (Sweden)

    Roher AE

    2012-10-01

    Full Text Available Alex E Roher,1 Josef P Debbins,2 Michael Malek-Ahmadi,3 Kewei Chen,4 James G Pipe,2 Sharmeen Maze,2 Christine Belden,3 Chera L Maarouf,1 Pradeep Thiyyagura,4 Hua Mo,4 Jesse M Hunter,1 Tyler A Kokjohn,1,5 Douglas G Walker,6 Jane C Kruchowsky,6 Marek Belohlavek,7 Marwan N Sabbagh,3 Thomas G Beach81The Longtine Center for Neurodegenerative Biochemistry, Banner Sun Health Research Institute, Sun City, 2Keller Center for Imaging Innovation, Neuroimaging Research, Barrow Neurological Institute, Phoenix, 3Cleo Roberts Center for Clinical Research, Banner Sun Health Research Institute, Sun City, 4Computational Image Analysis Program, Banner Alzheimer’s Institute, Phoenix, 5Department of Microbiology, Midwestern University, Glendale, 6Laboratory of Neuroinflammation, Banner Sun Health Research Institute, Sun City, 7Division of Cardiovascular Diseases, Mayo Clinic, Scottsdale, 8Civin Laboratory for Neuropathology, Banner Sun Health Research Institute, Sun City, AZ, USABackground: Alzheimer’s disease (AD dementia is a consequence of heterogeneous and complex interactions of age-related neurodegeneration and vascular-associated pathologies. Evidence has accumulated that there is increased atherosclerosis/arteriosclerosis of the intracranial arteries in AD and that this may be additive or synergistic with respect to the generation of hypoxia/ischemia and cognitive dysfunction. The effectiveness of pharmacologic therapies and lifestyle modification in reducing cardiovascular disease has prompted a reconsideration of the roles that cardiovascular disease and cerebrovascular function play in the pathogenesis of dementia.Methods: Using two-dimensional phase-contrast magnetic resonance imaging, we quantified cerebral blood flow within the internal carotid, basilar, and middle cerebral arteries in a group of individuals with mild to moderate AD (n = 8 and compared the results with those from a group of age-matched nondemented control (NDC subjects (n = 9

  17. Uteroplacental blood flow measured by placental scintigraphy during epidural anaesthesia for caesarean section

    Energy Technology Data Exchange (ETDEWEB)

    Skjoeldebrand, A.; Eklund, J.; Johansson, H.; Lunell, N.-O.; Nylund, L.; Sarby, B.; Thornstroem, S. (Departments of Anaesthesiology, Obstetrics and Gynaecology and Medical Physics, Karolinska Institute at Huddinge University Hospital, Stockholm (Sweden))

    1990-01-01

    The uteroplacental blood flow was measured before and during epidural anaesthesia for caesarean section in 11 woman. The blood flow was measured with dynamic placental scintigraphy. After an i.v. injection of indium-113m chloride, the gamma radiation over the placenta was recorded with a computer-linked scintillation camera. The uteroplacental blood flow could be calculated from the isotope accumulation curve. The anaesthesia was performed with bupivacaine plain 0.5%, 18-22 ml and a preload of a balanced electrolyte solution 10 ml/kg b.w. was given. The placental blood flow decreased in eight patients and increased in three with a median change of -21%, not being statistically significant. No correlation between maternal blood pressure and placental blood flow was found. (author).

  18. Cerebral angiography, blood flow and vascular reactivity in progressive hypertension

    Science.gov (United States)

    Li, Yunxia; Shen, Qiang; Huang, Shiliang; Li, Wei; Muir, Eric R.; Long, Justin; Duong, Timothy Q.

    2015-01-01

    Chronic hypertension alters cerebral vascular morphology, cerebral blood flow (CBF), cerebrovascular reactivity, increasing susceptibility to neurological disorders. This study evaluated: i) the lumen diameters of major cerebral and downstream arteries using magnetic resonance angiography, and ii) basal CBF, and iii) cerebrovascular reactivity to hypercapnia of multiple brain regions using arterial-spin-labeling technique in spontaneously hypertensive rats (SHR) at different stages. Comparisons were made with age-matched normotensive Wistar Kyoto (WKY) rats. In 10-week SHR, lumen diameter started to reduce, basal CBF, and hypercapnic CBF response were higher from elevated arterial blood pressure, but there was no evidence of stenosis, compared to age-matched WKY. In 20-week SHR, lumen diameter remained reduced, CBF returned toward normal from vasoconstriction, hypercapnic CBF response reversed and became smaller, but without apparent stenosis. In 40-week SHR, lumen diameter remained reduced and basal CBF further decreased, resulting in larger differences compared to WKY. There was significant stenosis in main supplying cerebral vessels. Hypercapnic CBF response further decreased, with some animals showing negative hypercapnic CBF responses in some brain regions, indicative of compromised cerebrovascular reserve. The territory with negative hypercapnia CBF responses corresponded with the severity of stenosis in arteries that supplied those territories. We also found enlargement of downstream vessels and formation of collateral vessels as compensatory responses to vasoconstriction upstream vessels. The middle cerebral and azygos arteries were amongst the most susceptible to hypertension-induced changes. Multimodal MRI provides clinically relevant data that might be useful to characterize disease pathogenesis, stage disease progression, and monitor treatment effects in hypertension. PMID:25731987

  19. Transient Non-Newtonian Blood Flow under Magnetic Targeting Drug Delivery in an Aneurysm Blood Vessel with Porous Walls

    Science.gov (United States)

    Alimohamadi, Haleh; Imani, Mohsen

    2014-11-01

    The present investigation deals with numerical solution of blood flow patterns through an aneurysm artery under the applied magnetic field. Transient extended Navier-Stokes, Brinkman, continuity, and heat conduction equations govern this phenomenon and unsteady pulsatile inlet velocity varies by human heart-beating frequency. Our simulation demonstrates applying 105 magnetic field intensity (MnF) to recirculate flow and increase fluid flux and maximum blood temperature by 62.5x and 3.5%, respectively, in the aneurysm region. It is also shown that the vessel's wall porosity plays an important role in magnetic targeting of drug delivery performance, as this parameter can noticeably change maximum blood temperature and pressure.

  20. Simple Radiowave-Based Method For Measuring Peripheral Blood Flow Project

    Science.gov (United States)

    Oliva-Buisson, Yvette J.

    2014-01-01

    Project objective is to design small radio frequency based flow probes for the measurement of blood flow velocity in peripheral arteries such as the femoral artery and middle cerebral artery. The result will be the technological capability to measure peripheral blood flow rates and flow changes during various environmental stressors such as microgravity without contact to the individual being monitored. This technology may also lead to an easier method of detecting venous gas emboli during extravehicular activities.

  1. Towards noninvasive method for the detection of pathological tissue variations by mapping different blood parameters

    Science.gov (United States)

    Abdallah, Omar; Qananwah, Qasem; Abo Alam, Kawther; Bolz, Armin

    2010-04-01

    This paper describes the development of an early detection method for probing pathological tissue variations. The method could be used for classifying various tissue alteration namely tumors tissue or skin disorders. The used approach is based on light scattering and absorption spectroscopy. Spectral content of the scattered light provides diagnostic information about the tissue contents. The importance of this method is using a safe light that has less power than the used in the imaging methods that will enable the frequent examination of tissue, while the exiting modalities have drawbacks like ionization, high cost, time-consuming, and agents' usage. A modality for mapping the oxygen saturation distribution in tissues noninvasively is new in this area of research, since this study focuses on the oxygen molecule in the tissue which supposed to be homogenously distributed through the tissues. Cancers may cause greater vascularization and greater oxygen consumption than in normal tissue. Therefore, oxygen existence and homogeneity will be alternated depending on the tissue state. In the proposed system, the signal was extracted after illuminating the tissue by light emitting diodes (LED's) that emits light in two wavelengths, red (660 nm) and infrared (880 nm). The absorption in these wavelengths is mainly due to oxyhemoglobin (HbO2) and deoxyhemoglobin (Hb) while other blood and tissue contents nearly have low effect on the signal. The backscattered signal which is received by a photodiodes array (128 PDs) was measured and processed using LabVIEW. Photoplethysmogram (PPG) signals have been measured at different locations. These signals will be used to differentiate between the normal and the pathological tissues. Variations in hemoglobin concentration and blood perfusion will also be used as an important indication feature for this purpose.

  2. Effects of vascular elastosis on uterine blood flow and perfusion in anesthetized mares.

    Science.gov (United States)

    Esteller-Vico, A; Liu, I K M; Vaughan, B; Steffey, E P; Brosnan, R J

    2015-04-01

    In the uterus of the mare, data obtained using transrectal Doppler ultrasonography indicate that uterine blood flow (UBF) is dynamic and changes throughout the estrous cycle. Degenerative lesions in the uterus are associated with subfertility and infertility. Among these lesions, vascular elastosis has been reported in aged, multiparous, and infertile mares. Angiosis of the uterine vasculature could potentially compromise UBF. The objectives of this experiment are to determine levels of UBF and perfusion of reproductively healthy mares and compare them to levels of subfertile/infertile mares affected by uterine vascular elastosis. Twenty mares were classified on the basis of degree of vascular degeneration and stage of cycle. A fluorescent microsphere technique was used to measure reproductive organ perfusion, where microspheres were injected into the left ventricle of the heart and became trapped in capillary beds in proportion to blood flow and tissue perfusion. The reproductive tract was removed, sectioned, and the fluorescent intensity evaluated to measure blood flow and perfusion. Additionally, full-thickness samples of the uterine wall were examined postmortem to further assess the degree of vascular degeneration in all layers of uterine wall. The mean value of uterine perfusion for the control mares during estrus (n = 5) was higher (P perfusion was not different (P > 0.05) during estrus (n = 5) and diestrus (n = 5); 5.9 and 7.2 mL/min/100g, respectively. Uterine perfusion in subfertile/infertile mares affected by elastosis was lower than that of control mares during both estrus (P perfusion between the control and elastosis groups indicate that elastosis of the uterine vasculature is associated with decreased uterine perfusion during both phases of the estrous cycle. In the uterus, a compromise in UBF could have implications in endometrial glandular development, postbreeding endometritis, uterine clearance, development of the conceptus, and

  3. A venous outflow method for measurement of rapid changes of the cerebral blood flow and oxygen consumption in the rat.

    Science.gov (United States)

    Nilsson, B; Siesjö, B K

    1983-01-01

    A technique for continuous measurement of cerebral venous outflow in the rat is described. The method involves cannulation of one retroglenoid vein close to its exit from the skull, and diversion of cerebral venous blood through a closed extracorporal circuit with a drop recording device, the blood being returned to the central venous circulation via a catheter in the external jugular vein. Occlusion of the contralateral retroglenoid vein increases measured flow and minimizes extracerebral contamination of the diverted cerebral venous blood. The venous outflow system is not further isolated from cerebral or potential extracerebral collaterals. Thus, the mass of tissue drained cannot be exactly defined anatomically. However, the experiments involving changes of PP, arterial CO2 tension, and induction of epileptic seizure activity, and simultaneous indirect measurements with radioactive tracer technique, indicate that significant extracerebral contamination does not occur and that in short term measurements the venous outflow represents cerebral blood flow (CBF) in a constant mass of (dorsal and central, mainly forebrain) cerebral tissue. Measurement of arterial blood pressure and pressure in the cisterna magna allows calculation of cerebral perfusion pressure (PP). By simultaneous measurement of arterial and cerebral venous oxygen content changes in cerebral oxygen consumption (CMRO2) can be calculated. The method has been applied to document several situations of transient CBF and CMRO2 changes. PMID:6658967

  4. Intensive blood pressure lowering increases cerebral blood flow in older subjects with hypertension.

    Science.gov (United States)

    Tryambake, Dinesh; He, Jiabao; Firbank, Michael J; O'Brien, John T; Blamire, Andrew M; Ford, Gary A

    2013-06-01

    Hypertension is associated with reduced cerebral blood flow (CBF). Intensive (blood pressure (BP) lowering in older people might give greater reduction in cardiovascular risk, but there are concerns that this might produce hypoperfusion which may precipitate falls and possibly stroke. We determined the effect of intensive compared with usual BP lowering on CBF in hypertensive older subjects. Individuals aged >70 years with a history of systolic hypertension on 1 or no BP lowering drugs were recruited from primary care (n=37; age, 75±4 years; systolic BP, >150 mm Hg) and randomized to receive intensive (target BP, treatment. Baseline BP (ambulatory or in clinic) and baseline gray matter CBF were not significantly different between the groups. After treatment, BP was reduced significantly in both groups but fell more in the intensive group (26/17 versus 15/5 mm Hg; Phypertension increases CBF, compared with BP lowering to usual target. These findings suggest hypertension in older people shifts the autoregulatory CBF curve rightward and downward and is reversible with BP lowering.

  5. Relationship between blood pressure and cerebral blood flow during supine cycling: influence of aging.

    Science.gov (United States)

    Smirl, Jonathan D; Hoffman, Keegan; Tzeng, Yu-Chieh; Hansen, Alex; Ainslie, Philip N

    2016-03-01

    The cerebral pressure-flow relationship can be quantified as a high-pass filter, where slow oscillations are buffered (TFA) findings (altered phase or intact gain). This study aimed to determine whether these previous findings accurately represent this relationship. Both younger (20-30 yr; n = 10) and older (62-72 yr; n = 9) adults were examined. To enhance the signal-to-noise ratio, large oscillations in blood pressure (via oscillatory lower body negative pressure; OLBNP) were induced during steady-state moderate intensity supine exercise (∼45-50% of heart rate reserve). Beat-to-beat blood pressure, cerebral blood velocity, and end-tidal Pco2 were monitored. Very low frequency (0.02-0.07 Hz) and low frequency (0.07-0.20 Hz) range spontaneous data were quantified. Driven OLBNP point estimates were sampled at 0.05 and 0.10 Hz. The OLBNP maneuvers augmented coherence to >0.97 at 0.05 Hz and >0.98 at 0.10 Hz in both age groups. The OLBNP protocol conclusively revealed the cerebrovascular system functions as a high-pass filter during exercise throughout aging. It was also discovered that the older adults had elevations (+71%) in normalized gain (+0.46 ± 0.36%/%: 0.05 Hz) and reductions (-34%) in phase (-0.24 ± 0.22 radian: 0.10 Hz). There were also age-related phase differences between resting and exercise conditions. It is speculated that these age-related changes in the TFA metrics are mediated by alterations in vasoactive factors, sympathetic tone, or the mechanical buffering of the compliance vessels. PMID:26586907

  6. Evaluation of periodontal tissues condition in children with blood coagulability pathology

    OpenAIRE

    Gavrilenko, M. A.

    2014-01-01

    Background. Actuality of the problem is determined by the high prevalence of inflammatory diseases of periodontal tissues in children with blood pathology (100%). Primary prevention of dental caries and periodontal diseases has the exceptional importance in the dentist’s work with children who have blood coagulability disorders. Prevention of dental diseases of the oral cavity in this category of patients has a number of features because there is the risk of bleeding during both home oral hyg...

  7. Biological and engineering design considerations for vascular tissue engineered blood vessels (TEBVs)

    OpenAIRE

    Fernandez, Cristina E.; Achneck, Hardean E.; Reichert, William M.; Truskey, George A.

    2014-01-01

    Considerable advances have occurred in the development of tissue-engineered blood vessels (TEBVs) to repair or replace injured blood vessels, or as in vitro systems for drug toxicity testing. Here we summarize approaches to produce TEBVs and review current efforts to (1) identify suitable cell sources for the endothelium and vascular smooth muscle cells, (2) design the scaffold to mimic the arterial mechanical properties and (3) regulate the functional state of the cells of the vessel wall. I...

  8. Non-Coding CK19 RNA in Peripheral Blood and Tissue of Breast Cancer Patients

    OpenAIRE

    Neda Moazzezy; Saeid Bouzari; Najmeh Yardehnavi; Mana Oloomi

    2013-01-01

    Breast carcinoma is the major cause of cancer-related death in women. The incidence of this carcinoma is rising and there are many attempts to decrease this problem. The aim of this study was detection of full-length cytokeratin 19 (CK19) mRNA, in peripheral blood and tissue of breast cancer patients in early stage of cancer. In this study, RT-PCR (reverse transcriptase-polymerase chain reaction) technique was used for detection of CK19 mRNA in peripheral blood and tissue of breast cancer pat...

  9. Eigenspectra optoacoustic tomography achieves quantitative blood oxygenation imaging deep in tissues

    Science.gov (United States)

    Tzoumas, Stratis; Nunes, Antonio; Olefir, Ivan; Stangl, Stefan; Symvoulidis, Panagiotis; Glasl, Sarah; Bayer, Christine; Multhoff, Gabriele; Ntziachristos, Vasilis

    2016-06-01

    Light propagating in tissue attains a spectrum that varies with location due to wavelength-dependent fluence attenuation, an effect that causes spectral corruption. Spectral corruption has limited the quantification accuracy of optical and optoacoustic spectroscopic methods, and impeded the goal of imaging blood oxygen saturation (sO2) deep in tissues; a critical goal for the assessment of oxygenation in physiological processes and disease. Here we describe light fluence in the spectral domain and introduce eigenspectra multispectral optoacoustic tomography (eMSOT) to account for wavelength-dependent light attenuation, and estimate blood sO2 within deep tissue. We validate eMSOT in simulations, phantoms and animal measurements and spatially resolve sO2 in muscle and tumours, validating our measurements with histology data. eMSOT shows substantial sO2 accuracy enhancement over previous optoacoustic methods, potentially serving as a valuable tool for imaging tissue pathophysiology.

  10. Eigenspectra optoacoustic tomography achieves quantitative blood oxygenation imaging deep in tissues

    Science.gov (United States)

    Tzoumas, Stratis; Nunes, Antonio; Olefir, Ivan; Stangl, Stefan; Symvoulidis, Panagiotis; Glasl, Sarah; Bayer, Christine; Multhoff, Gabriele; Ntziachristos, Vasilis

    2016-01-01

    Light propagating in tissue attains a spectrum that varies with location due to wavelength-dependent fluence attenuation, an effect that causes spectral corruption. Spectral corruption has limited the quantification accuracy of optical and optoacoustic spectroscopic methods, and impeded the goal of imaging blood oxygen saturation (sO2) deep in tissues; a critical goal for the assessment of oxygenation in physiological processes and disease. Here we describe light fluence in the spectral domain and introduce eigenspectra multispectral optoacoustic tomography (eMSOT) to account for wavelength-dependent light attenuation, and estimate blood sO2 within deep tissue. We validate eMSOT in simulations, phantoms and animal measurements and spatially resolve sO2 in muscle and tumours, validating our measurements with histology data. eMSOT shows substantial sO2 accuracy enhancement over previous optoacoustic methods, potentially serving as a valuable tool for imaging tissue pathophysiology. PMID:27358000

  11. Tissue banking: relationship with blood donor and organ donor card status.

    Science.gov (United States)

    McKenzie, Kenneth D; Fitzpatrick, Patricia E; Sheehan, John D

    2012-01-01

    Understanding the relationships among altruistic health acts may serve to aid therapeutic research advances. In this paper, we report on the links between two such behaviours-donating blood and carrying an organ donor card-and willingness to donate urological tissue to a tissue bank. Reasons for the differential willingness to do so are examined in this paper. A systematic sample of 259 new and returning attendees at a tertiary urology referral clinic in Ireland completed a self-report questionnaire in an outpatient setting. In addition to demographic details, details of known diagnosis of malignancy and family history of cancer; attitudes to tissue donation for research purposes were gauged using a 5-point Likert scale. Both blood donors and organ donor card carriers were more likely to be willing to donate tissue for research purposes. Blood donors were more likely want to know their overall results in comparison to nonblood donors and want their samples to be used for nonprofit research. Our hypothesis that being a blood donor would be a better predictor to donate urological tissue than being an organ donor card carrier borne out by the trends reported above. PMID:22567418

  12. A rapid, non enzymatic method for genomic DNA extraction from whole blood and mammalian tissues

    Directory of Open Access Journals (Sweden)

    Adnan F. N Al-azawy

    2011-05-01

    Full Text Available Although several methods have been exist for DNA extraction from blood or animal tissues samples, traditionally most of these methods consume long time and using expensive chemicals such as proteinase K or toxic organic solvent such as phenol. On the other hand, there is no rapid, simple one method for the extraction of genomic DNA from blood and animal tissues samples in the same time. Since the objective of this study was to development easy modified method for DNA extraction from difference mammalian tissues such as fresh or frozen whole blood, kidney, liver, heart, muscles. The description method have many advantages, reducing the time, using inexpensive materials, no phenol, in addition to small amount of mammalian tissue is required (100-200 mg and 2 ml from whole blood. Genomic DNA was obtained having high molecular weight and good quality, shown by agarose gel electrophoresis and spectrophtometric analysis. These results shown that the modified method is simple, fast, safe, most economical, resulting in a high molecular genomic DNA of good quality from several mammalian tissues and can be used in medical laboratories and research centers.

  13. Regulatory T Cells in HIV-Infected Immunological Nonresponders Are Increased in Blood but Depleted in Lymphoid Tissue and Predict Immunological Reconstitution

    DEFF Research Database (Denmark)

    Gaardbo, Julie C; Hartling, Hans J; Ronit, Andreas;

    2014-01-01

    BACKGROUND: HIV-infected immunological nonresponders fail to immune reconstitute despite optimal treatment. We hypothesized that regulatory T cells (Tregs) are involved in immunological reconstitution. Tregs and Treg subpopulations were measured in blood and Foxp3 cells in lymphoid tissue...... (CD4 T-cell count 200-500 cells/μL), 30 responders (CD4 T-cell count >500 cells/μL), and 34 healthy controls. Tregs, Treg subpopulations, and intracellular staining for interleukin 10 in peripheral blood were measured using flow cytometry. Foxp3 cells in lymphoid tissue were evaluated using...... immunolabeling. The CD4 T-cell count was determined at inclusion and after 1 year of follow-up. RESULTS: INR displayed high percentage of Tregs and activated Tregs in peripheral blood accompanied by a high percentage of Tregs expressing interleukin 10, whereas numbers of Foxp3 cells in lymphoid tissue were low...

  14. Visualization and measurement of capillary-driven blood flow using spectral domain optical coherence tomography

    OpenAIRE

    Cito, Salvatore; Ahn, Yeh-Chan; Pallares, Jordi; Duarte, Rodrigo Martinez; Chen, Zhongping; Madou, Marc; Katakis, Ioanis

    2012-01-01

    Capillary-driven flow (CD-flow) in microchannels plays an important role in many microfluidic devices. These devices, the most popular being those based in lateral flow, are becoming increasingly used in health care and diagnostic applications. CD-flow can passively pump biological fluids as blood, serum or plasma, in microchannels and it can enhance the wall mass transfer by exploiting the convective effects of the flow behind the meniscus. The flow behind the meniscus has not been experimen...

  15. Effect of selective occlusion of the umbilical arteries and/or veins on uterine blood flow in sheep.

    Science.gov (United States)

    Hasaart, T H; de Haan, J; Horiguchi, T

    1986-01-01

    Maternal uterine blood flow was depressed during total umbilical cord occlusion, probably based on an increased fetal cotyledonary tissue pressure (Hasaart and de Haan (1985) Eur. J. Obstet. Gynec. Reprod. Biol., 19, 125-131). This supposed mechanism was further analysed by performing selective occlusions of the umbilical arteries and/or veins (mean occlusion time 35 s). An occluding device which allowed separate occlusion of umbilical veins and arteries was applied to the umbilical cord in 7 chronically prepared fetal lambs between 106 and 135 days gestation. Median uterine artery blood flow (UBF) was measured with an electromagnetic flow meter. During occlusion of both umbilical veins (VV, n = 22) in 6 animals a maximal decrease in UBF to 87.5% of control value (P less than 0.001) was found at the end occlusion, followed by a gradual return to control value in the post occlusion period. Occlusion of both umbilical arteries (AA, n = 29) in 5 animals was accompanied by a slight increase in UBF to 103% of control value (P less than 0.01). Total occlusion of the umbilical arteries and veins simultaneously (n = 17) in 4 animals did not result in any change in UBF. The changes in volume and turgor in the fetal cotyledonary tissue associated with the arterial and venous occlusions should lead to respectively a decrease (AA) and increase (VV) in resistance to maternal flow, causing the changes in uterine blood flow. It is concluded that volume changes in the fetal compartment of the sheep placenta affect maternal uterine blood flow. PMID:3956829

  16. In vivo analysis of physiological 3D blood flow of cerebral veins

    Energy Technology Data Exchange (ETDEWEB)

    Schuchardt, Florian; Schroeder, Laure; Baeuerle, Jochen; Harloff, Andreas [University Medical Centre, Department of Neurology, Freiburg (Germany); Anastasopoulos, Constantin [University Medical Center, Department of Neuropaediatrics and Muscle Disorders, Freiburg (Germany); University Medical Centre, Department of Neuroradiology, Freiburg (Germany); Markl, Michael [Northwestern University, Department of Radiology, Feinberg School of Medicine and McCormick School of Engineering, Chicago, IL (United States); Hennemuth, Anja; Drexl, Johann [Fraunhofer MEVIS, Bremen (Germany); Valdueza, Jose M. [Neurological Center, Segeberger Kliniken, Bad Segeberg (Germany); Mader, Irina [University Medical Centre, Department of Neuroradiology, Freiburg (Germany)

    2015-08-15

    To visualize and quantify physiological blood flow of intracranial veins in vivo using time-resolved, 3D phase-contrast MRI (4D flow MRI), and to test measurement accuracy. Fifteen healthy volunteers underwent repeated ECG-triggered 4D flow MRI (3 Tesla, 32-channel head coil). Intracranial venous blood flow was analysed using dedicated software allowing for blood flow visualization and quantification in analysis planes at the superior sagittal, straight, and transverse sinuses. MRI was evaluated for intra- and inter-observer agreement and scan-rescan reproducibility. Measurements of the transverse sinuses were compared with transcranial two-dimensional duplex ultrasound. Visualization of 3D blood flow within cerebral sinuses was feasible in 100 % and within at least one deep cerebral vein in 87 % of the volunteers. Blood flow velocity/volume increased along the superior sagittal sinus and was lower in the left compared to the right transverse sinus. Intra- and inter-observer reliability and reproducibility of blood flow velocity (mean difference 0.01/0.02/0.02 m/s) and volume (mean difference 0.0002/-0.0003/0.00003 l/s) were good to excellent. High/low velocities were more pronounced (8 % overestimation/9 % underestimation) in MRI compared to ultrasound. Four-dimensional flow MRI reliably visualizes and quantifies three-dimensional cerebral venous blood flow in vivo and is promising for studies in patients with sinus thrombosis and related diseases. (orig.)

  17. Tissue Banking: Relationship with Blood Donor and Organ Donor Card Status

    OpenAIRE

    McKenzie, Kenneth D.; Fitzpatrick, Patricia E.; Sheehan, John D.

    2012-01-01

    Understanding the relationships among altruistic health acts may serve to aid therapeutic research advances. In this paper, we report on the links between two such behaviours—donating blood and carrying an organ donor card—and willingness to donate urological tissue to a tissue bank. Reasons for the differential willingness to do so are examined in this paper. A systematic sample of 259 new and returning attendees at a tertiary urology referral clinic in Ireland completed a self-report questi...

  18. Depth discrimination in acousto-optic cerebral blood flow measurement simulation

    Science.gov (United States)

    Tsalach, A.; Schiffer, Z.; Ratner, E.; Breskin, I.; Zeitak, R.; Shechter, R.; Balberg, M.

    2016-03-01

    Monitoring cerebral blood flow (CBF) is crucial, as inadequate perfusion, even for relatively short periods of time, may lead to brain damage or even death. Thus, significant research efforts are directed at developing reliable monitoring tools that will enable continuous, bed side, simple and cost-effective monitoring of CBF. All existing non invasive bed side monitoring methods, which are mostly NIRS based, such as Laser Doppler or DCS, tend to underestimate CBF in adults, due to the indefinite effect of extra-cerebral tissues on the obtained signal. If those are to find place in day to day clinical practice, the contribution of extra-cerebral tissues must be eliminated and data from the depth (brain) should be extracted and discriminated. Recently, a novel technique, based on ultrasound modulation of light was developed for non-invasive, continuous CBF monitoring (termed ultrasound-tagged light (UTL or UT-NIRS)), and shown to correlate with readings of 133Xe SPECT and laser Doppler. We have assembled a comprehensive computerized simulation, modeling this acousto-optic technique in a highly scattering media. Using the combination of light and ultrasound, we show how depth information may be extracted, thus distinguishing between flow patterns taking place at different depths. Our algorithm, based on the analysis of light modulated by ultrasound, is presented and examined in a computerized simulation. Distinct depth discrimination ability is presented, suggesting that using such method one can effectively nullify the extra-cerebral tissues influence on the obtained signals, and specifically extract cerebral flow data.

  19. Impedance cardiography: Pulsatile blood flow and the biophysical and electrodynamic basis for the stroke volume equations

    Directory of Open Access Journals (Sweden)

    Donald P Bernstein

    2010-01-01

    , and more precisely, the electro-dynamic equivalent of peak aortic reduced average blood acceleration (PARABA, d/dtmax/R, s-2. As necessary for stroke volume calculation, dZ/dtmax/Z0 must undergo square root transformation to yield an ohmic mean flow velocity equivalent. To compute SV, the square root of the dimensionless ohmic mean acceleration equivalent ([dZ/dtmax/Z0]0.5, s-1 is multiplied by a volume of electrically participating thoracic tissue (VEPT, mL and left ventricular ejection time (TLVE, s. To find the bulk volume of the thoracic contents (i.e. VEPT, established methods implement exponential functions of measured thoracic length (L(cmn or height-based thoracic length equivalents (0.01×%H(cmn. The new method conceptualizes VEPT as the intrathoracic blood volume (ITBV, mL, which is approximated through allometric equivalents of body mass (aMb. In contrast to the classical two-element parallel conduction model, the new method comprises a three-compartment model, which incorporates excess extra-vascular lung water (EVLW as a component of both Z0 and VEPT. To fully appreciate the evolution and analytical justification for impedance-derived SV equations, a review of the basics of pulsatile blood flow is in order.

  20. In vivo cerebral blood flow autoregulation studies using rheoencephalography

    Science.gov (United States)

    Bodo, M.; Pearce, F.; Garcia, A.; Van Albert, S.; Settle, T.; Szebeni, J.; Baranyi, L.; Hartings, J.; Armonda, R.

    2010-04-01

    Acute management of patients with traumatic brain/blast injury is a challenge. To minimize secondary injury and improve outcome, it is critical to detect neurological deterioration early, when it is potentially reversible. One potential monitoring method is cerebral electrical impedance (rheoencephalography-REG) because of its non-invasiveness and good time resolution. Reported here are the results of cerebral blood flow (CBF) manipulations comparing electroencephalogram (EEG) with REG (both intra-cerebral) and measuring with surface and skull REG electrodes. Our hypothesis was that REG would reflect spreading depression and CBF autoregulation. Animal experiments were performed using one rat (four trials with intracerebral electrodes), monkeys (n=8, with surface electrodes) and pigs (n = 24 pigs with skull electrodes; 57 trials, 19 types of liposomes). Challenges included intracranial pressure (ICP) elevation, liposome infusion, and hemorrhage. Data were stored on a PC and evaluated off line. CBF autoregulation was evaluated both by visual inspection and by a Matlab script. These studies confirmed that REG reflects CBF autoregulation and that REG is useful for detecting spreading depression (SD), vasospasm and the lower limit of CBF autoregulation. These findings have clinical relevance for use in noninvasive neuro-monitoring in the neurosurgery intensive care and during transportation of patients with brain injury.