Sample records for reperfusion blood flow

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

    Institute of Scientific and Technical Information of China (English)

    Hu Sen; Sheng Zhiyong


    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.

  2. The effects of anisodamine and dobutamine on gut mucosal blood flow during gut ischemia/reperfusion

    Institute of Scientific and Technical Information of China (English)

    Sen Hu; Zhi-Yong Sheng


    AIM: To determine if anisodamine is able to augmentmucosal perfusion during gut I/R ischemia-reperfusion.METHODS: A jejunal sec wes formed in Sprague Dawley rat.A Laser Doppler probe and a tonometer were inserted intothe sac which was filled with saline. The superiormesenteric artery was occluded (SMAO)for 60 minutesfollowed by 90 minutes of reperfusion. At the end of 60minutes of SMAO, either 0. 2 mg/kg of anisodmine ordobutamine was injected into the jejunal sac. Laser Dopplermucosal blood flow and regional PCO2 ( PrCO2 )measurements were made.RESULTS: Mucosal blood flow was significantly increased at30,60 and 90 minutes of reperfusion (R30, R60, R90 ) whenintraluminal anisodamine or dobutamine was presentcompared to intraluminal saline only(44 + 3.3 % or 48 + 4. 1% vs37+2.6% atR30, 57+5.0% or56+4.7 % vs45+2.7% atR60, 64+3.3% or56+4.2 % vs48+3.4 % atR90,respectively P < 0. 05 ). Blood flow changes were alsoreflected by lowering of jejunal PrCO2 measurements afterintraluminal anisodamine or dobutamine compared with thatof the saline controls (41 + 3. 1 mmHg or 44 ± 3.0 mmHg vs49 + 3.7 mmHg at R30, 38 + 3.7 mmHg or 40 + 2. 1 mmHg vs 47+ 3.8 mmHg at R60, 34 + 2. 1 mmHg or 39 + 3.0 mmHg vs 46 3.4 mmHg at R90, respectively, P< 0.05). Most interestingfinding wes that there were significantly higher mucosalblood flow and lower jejunal PrCO2 in anisodamine groupthan those in dobutamine group at 90 minutes of reperfusion(64+ 3.3 % vs 56 + 4.2 % for blood flow or 34 + 2. 1 mmHgvs 39 + 3.0 mmHg for PrCO2, respectively, P < 0. 05 ),suggesting that anisodamine had a more lasting effect onmucosal perfusion than dobutamine.CONCLUSION: Intraluminal anisodamine and dobutaminecan augment mucosal blood flow during gut I/R and alleviatemucosal acidosis. The results provided benificial effects onthe treatment of splanchnic hypoperfusion followingtraumatic or burn shock.

  3. Evaluation of hemolysis in microcatheter directed blood infusion at different flow rates for transarterial salvage reperfusion: In-vitro study. (United States)

    Froelich, Jens J; Ray, Udayan; Monkhorst, Jessica; Marwick, Thomas H; Hardikar, Ashutosh; Harle, Robin; Carr, Michael W


    Microcatheter directed blood reperfusion is an endovascular salvage option for acute cerebral artery occlusions. It has not been investigated whether this technique may be associated with hemolysis. Analysis of hemolysis during blood infusion through different microcatheters and infusion rates to assess related risks. Four microcatheters with different inner diameters were perfused with blood samples at three infusion rates. Hemolytic markers including lactate-dehydrogenase (LDH) and haptoglobin were analyzed. Samples before and after blood infusion were compared using Student's t-test. Flow-related degree of hemolysis was analyzed with regression analysis. Resulting shear stress was calculated and correlated with LDH and haptoglobin. Significant increase of LDH and decrease of haptoglobin was found after blood reperfusion through small microcatheters at progressive flow rates (phemolysis was found with larger diameter microcatheters at all flow rates (p>0.05). Correlation between shear stress, LDH and haptoglobin was r=0.86 and r=0.75, respectively. Progressive hemolysis occurs during blood perfusion of small lumen microcatheters at increasing flow rates. This phenomenon may be related to turbulent flow, exposure time and increased shear stress. Larger microcatheters did not induce hemolysis and may be the preferred choice for stroke reperfusion.

  4. Effect of Perfluorane on the Amplitude-Frequency Spectrum of Fluctuations in Cerebral Blood Flow in Hemorrhagic Hypotension and During the Reperfusion Period

    Directory of Open Access Journals (Sweden)

    I. A. Ryzhkov


    Full Text Available Objective: to use laser Doppler flowmetry (LDF to investigate the effect of perfluorane on the time course of microhemocirculato ry changes in the rat pial vessels in acute blood loss and after autohemotransfusion.Material and methods. Experiments were car ried out on 31 outbred male rats weighing 300—400 g under anesthesia with intraperitoneal Nembutal 45 mg/kg. The caudal artery was catheterized to measure blood pressure (BP, to sample and reinfuse blood, and to administer infusion solutions. LDF (ЛАКК 02 device, LAZMA, Russia was used to record blood flow in the pial vessels of the left parietal region (the center coordinates were 3 mm caudal to bregma and 2 mm left of the sagittal suture. A volumefixed acute blood loss model was applied. The goal amount of blood loss was 30% of the circulating blood volume. At 10 minutes after blood sampling, the animals were administered 0.9% NaCl solution (physiologic saline (PS, n=15 or perfluorane (PF, n=16 in a dose of 3 ml/kg body weight. At 60 minutes following blood sampling, autohemotransfusion was used, after which there was a 60min reperfusion period. The investigators analyzed LDF readings and determined the following indicators: microcirculation index; the maximum amplitudes of blood flow fluctuations in the endothelial, neurogenic, and myogenic frequency ranges by a wavelet analysis. The data were statistically processed using Statistica 7.0 software.Results. Hypovolemia caused a more than 50% reduction in BP; moreover, blood flow in the pial vessels decreased by less than 20% of its baseline level (p<0.05. In the same period, there was an increase in the amplitude of flux motions mainly in the neurogenic (NA frequency. The differences in microcirculatory parameters between the PS or PF groups were in the retention of higher NA in the PS group throughout hypovolemia; at the same time the groups did not differ in the arterial blood levels of the index of perfusion (IP, рСО2, and

  5. Intraportal versus Systemic Pentoxifylline Infusion after Normothermic Liver Ischemia: Effects on Regional Blood Flow Redistribution and Hepatic Ischemia-Reperfusion Injury

    Directory of Open Access Journals (Sweden)

    Edson A. Ribeiro


    Full Text Available Pentoxifylline (PTX has been shown to have beneficial effects on microcirculatory blood flow. In this study we evaluate the potential hemodynamic and metabolic benefits of PTX during hepatic ischemia. We also test the hypothesis that portal PTX infusion can minimize the I/R injury when compared to systemic infusion. Methods. Twenty-four dogs ( kg were subjected to portal triad occlusion (PTO for 45 min. The animals were assigned to 3 groups: CT (control, PTO, , PTX-syst (PTO + 25 mg/Kg of PTX IV, , and PTX-pv (PTO + 25 mg/Kg of PTX in the portal vein, . Animals were followed for 120 min. Systemic hemodynamics, gastrointestinal tract perfusion, oxygen-derived variables, and liver enzymes were evaluated throughout the experiment. Results. Animals treated with PTX presented significantly higher CO in the first hour after reperfusion, when compared to the CT (~3.7 vs. 2.1 L/min, . Alanine aminotransferase (ALT was similar in the PTX groups two hours after reperfusion but significantly higher in the CT (227 vs. ~64 U/L, . Conclusion. PTX infusion was associated with hemodynamic benefits and was able to minimize liver injury during normothermic hepatic I/R. However, local PTX infusion was not associated with any significant advantage over systemic route.

  6. Role of eicosanoids and white blood cells in the beneficial effects of limited reperfusion after ischemia-reperfusion injury in skeletal muscle

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    Anderson, R.J.; Cambria, R.A.; Dikdan, G.; Lysz, T.W.; Hobson, R.W. II (UMDNJ-New Jersey Medical School, Newark (USA))


    Limiting the rate of reperfusion blood flow has been shown to be beneficial locally in models of ischemia-reperfusion injury. We investigated the effects of this on eicosanoids (thromboxane B2, 6-keto-PGF1 alpha, and leukotriene B4), white blood cell activation, and skeletal muscle injury as quantitated by triphenyltetrazolium chloride and technetium-99m pyrophosphate after ischemia-reperfusion injury in an isolated gracilis muscle model in 16 anesthetized dogs. One gracilis muscle in each dog was subjected to 6 hours of ischemia followed by 1 hour of limited reperfusion and then by a second hour of normal reperfusion. The other muscle was subjected to 6 hours of ischemia followed by 2 hours of normal reperfusion. Six dogs each were used as normal reperfusion controls (NR) and limited reperfusion controls (LR), with 5 dogs being treated with a thromboxane synthetase inhibitor (LR/TSI) and another five with a leukotriene inhibitor (LR/LI). LR in all three groups (LR, LR/TSI, and LR/LI) showed a benefit in skeletal muscle injury as measured by triphenyltetrazolim chloride and technetium-99m pyrophosphate when compared with NR. However, there was no significant difference between the groups with LR regarding eicosanoid levels and white blood cell activation when compared with NR. These results demonstrate that LR produces benefits by mechanisms other than those dependent upon thromboxane A2, prostacyclin, or white blood cell activation.

  7. Conditioned blood reperfusion during angioplasty (CoBRA) treatment of acute myocardial infarction. (United States)

    Patel, M B; Kilgore, K S; Ortolano, G A; Gryboski, C L; Qureshi, M A; Marcovitz, P; Naylor, K B; Park, J L; Wenz, B; Gikakis, N; Freedman, R J; Lucchesi, B R; O'Neill, W W


    Acute myocardial infarct (MI) results in ischemia distal to lesions which puts heart muscle at risk for reperfusion injury (RI). Neutrophils, platelets and complement are putative mediators of RI. Recent advances in filtration technology provide integrated neutrophil and platelet removal together with complement-attenuating properties in a single blood-conditioning device. The present study characterizes the properties of a blood-conditioning filter and describes its clinical effect when used in conjunction with active hemoperfusion for acute MI. The filter reduces leukocytes by 99.9998 +/- 0.0002% (pheart preparation. The deposition of membrane attack complex and the resultant functional myocardial impairments [reflected in hemodynamic and biochemical measurements, including developed pressure, coronary blood flow, lymph-derived myocardial creatine kinase (CK)] are significantly attenuated by blood conditioning. Integration of the blood-conditioning filter into an active hemoperfusion system during primary percutaneous transluminal coronary angioplasty (PTCA) for acute MI (n=8) did not delay the procedure or cause any complications. Reperfusion of occluded coronary arteries with 300 cm3 of conditioned blood led to significant improvement in echocardiographic global wall motion scores (in standard deviations) following treatment (-1.64 +/- 0.18 to -1.45 +/- 0.15, p=0.02). Initial reperfusion of totally occluded coronary arteries with conditioned blood leads to acutely improved ventricular function. Collectively, these data provide a strong indication for continued investigation of conditioned blood reperfusion in angioplasty following acute MI for the long-term effect upon recovery of salvagable myocardium.

  8. Blood flow (United States)

    ... the same time, the veins carry oxygen-poor blood (shown in blue) from the tissues back toward the heart. From there, it passes to the lungs to receive more oxygen. This cycle repeats itself when oxygen-rich blood returns to the heart from the lungs, which ...

  9. Effect of eye acupuncture on cerebral blood flow and velocity in rats with ischemia-reperfusion%眼针对大鼠脑缺血再灌注脑血流量及速度影响

    Institute of Scientific and Technical Information of China (English)

    吴翊馨; 张海平; 苏胜林


    Objective To observe the effect of eye acupuncture on cerebral blood flow and velocity in rats with cerebral ischemia reperfusion(ICRI) and to explore the mechanisms of eye acupunture treatment to cerebral ischencic diseases.Methods Laser Doppler microcirculation measurement instrument was used to measure blood flow and velocity of cerebnal cortex in rats 24 hours after cerebral ischemia.The structural changes in the capillary loops of the cortex was observed with electron microscope.Results The blood flow of cerebral cortex was 63.28 ± 8.84 PU for ischemic model rats and 169.39 ± 19.89 for the model rats with eye acupuncture,and the blood flow velocity was 19.98 ±6.75 mm/s for the model rats and 57.43 ± 28.54 mm/s for the model rats with eye acupucture,respectively,with significant defferences between the two groups(P < 0.01 for all).The ultrastructure of cerebral cortex capillary was normal for model rats with eye acupuntrre but necrosis and atrophy of capillary endothelial cells were observed in cerebral ischemic model rats.Conclusion Eye acupucture can increase blood flow and velocity of cortex tissue in rats with ICRI and improve ultrastructure of the capillary endothelial cells in rats with ICRI.%目的 观察眼针对脑缺血再灌注模型(CIRI)大鼠脑皮层血流量及流速影响,探讨眼针治疗脑缺血性疾病的可能机制.方法 运用激光多普勒微循环测量仪检测缺血24 h模型大鼠大脑皮层组织血流量及血流速度;观察电镜下毛细血管管壁的结构变化.结果 模型组与眼针组大鼠大脑皮层组织血流量与血流速度分别为(63.28 ±8.84)、(169.38±19.89) PU和(18.98 ±6.75)、(57.43±28.84) mm/s,与模型组比较,眼针组大鼠大脑皮层组织的血流量明显升高、血流速度明显加快(P<0.01);眼针组大鼠大脑皮层毛细血管的超微结构基本正常,模型组内皮细胞坏死、萎缩.结论 眼针能够增加ICRI模型大鼠脑皮层组织血流量,提高血流

  10. Blood flow and microgravity (United States)

    Bureau, Lionel; Coupier, Gwennou; Dubois, Frank; Duperray, Alain; Farutin, Alexander; Minetti, Christophe; Misbah, Chaouqi; Podgorski, Thomas; Tsvirkun, Daria; Vysokikh, Mikhail


    The absence of gravity during space flight can alter cardio-vascular functions partially due to reduced physical activity. This affects the overall hemodynamics, and in particular the level of shear stresses to which blood vessels are submitted. Long-term exposure to space environment is thus susceptible to induce vascular remodeling through a mechanotransduction cascade that couples vessel shape and function with the mechanical cues exerted by the circulating cells on the vessel walls. Central to such processes, the glycocalyx - i.e. the micron-thick layer of biomacromolecules that lines the lumen of blood vessels and is directly exposed to blood flow - is a major actor in the regulation of biochemical and mechanical interactions. We discuss in this article several experiments performed under microgravity, such as the determination of lift force and collective motion in blood flow, and some preliminary results obtained in artificial microfluidic circuits functionalized with endothelium that offer interesting perspectives for the study of the interactions between blood and endothelium in healthy condition as well as by mimicking the degradation of glycocalyx caused by long space missions. A direct comparison between experiments and simulations is discussed. xml:lang="fr"

  11. Methylene blue protects the cortical blood-brain barrier against ischemia/reperfusion-induced disruptions. (United States)

    Miclescu, Adriana; Sharma, Hari Shanker; Martijn, Cécile; Wiklund, Lars


    To investigate the effects of cardiac arrest and the reperfusion syndrome on blood-brain barrier permeability and evaluate whether methylene blue counteracts blood-brain barrier disruption in a pig model of controlled cardiopulmonary resuscitation. Randomized, prospective, laboratory animal study. University-affiliated research laboratory. Forty-five piglets. Forty-five anesthetized piglets were subjected to cardiac arrest alone or 12-min cardiac arrest followed by 8 mins cardiopulmonary resuscitation. The first group (n = 16) was used to evaluate blood-brain barrier disruptions after untreated cerebral ischemia after 0, 15, or 30 mins after untreated cardiac arrest. The other two groups received either an infusion of saline (n = 10) or infusion of saline with methylene blue (n = 12) 1 min after the start of cardiopulmonary resuscitation and continued 50 mins after return of spontaneous circulation. In these groups, brains were removed for immunohistological analyses at 30, 60, and 180 mins after return of spontaneous circulation. An increase of injured neurons and albumin immunoreactivity was demonstrated with increasing duration of ischemia/reperfusion. Less blood-brain barrier disruption was observed in subjects receiving methylene blue as demonstrated by decreased albumin leakage (p blue treatment reduced cerebral tissue nitrite/nitrate content (p blood-brain barrier permeability and neurologic injury were increased early in reperfusion after cardiac arrest. Methylene blue exerted neuroprotective effects against the brain damage associated with the ischemia/reperfusion injury and ameliorated the blood-brain barrier disruption by decreasing nitric oxide metabolites.

  12. Resting cerebral blood flow (United States)

    Ances, B M.; Sisti, D; Vaida, F; Liang, C L.; Leontiev, O; Perthen, J E.; Buxton, R B.; Benson, D; Smith, D M.; Little, S J.; Richman, D D.; Moore, D J.; Ellis, R J.


    Objective: HIV enters the brain soon after infection causing neuronal damage and microglial/astrocyte dysfunction leading to neuropsychological impairment. We examined the impact of HIV on resting cerebral blood flow (rCBF) within the lenticular nuclei (LN) and visual cortex (VC). Methods: This cross-sectional study used arterial spin labeling MRI (ASL-MRI) to measure rCBF within 33 HIV+ and 26 HIV− subjects. Nonparametric Wilcoxon rank sum test assessed rCBF differences due to HIV serostatus. Classification and regression tree (CART) analysis determined optimal rCBF cutoffs for differentiating HIV serostatus. The effects of neuropsychological impairment and infection duration on rCBF were evaluated. Results: rCBF within the LN and VC were significantly reduced for HIV+ compared to HIV− subjects. A 2-tiered CART approach using either LN rCBF ≤50.09 mL/100 mL/min or LN rCBF >50.09 mL/100 mL/min but VC rCBF ≤37.05 mL/100 mL/min yielded an 88% (29/33) sensitivity and an 88% (23/26) specificity for differentiating by HIV serostatus. HIV+ subjects, including neuropsychologically unimpaired, had reduced rCBF within the LN (p = 0.02) and VC (p = 0.001) compared to HIV− controls. A temporal progression of brain involvement occurred with LN rCBF significantly reduced for both acute/early (<1 year of seroconversion) and chronic HIV-infected subjects, whereas rCBF in the VC was diminished for only chronic HIV-infected subjects. Conclusion: Resting cerebral blood flow (rCBF) using arterial spin labeling MRI has the potential to be a noninvasive neuroimaging biomarker for assessing HIV in the brain. rCBF reductions that occur soon after seroconversion possibly reflect neuronal or vascular injury among HIV+ individuals not yet expressing neuropsychological impairment. GLOSSARY AEH = acute/early HIV infection; ANOVA = analysis of variance; ASL-MRI = arterial spin labeling MRI; CART = classification and regression tree; CBF = cerebral blood flow; CH = chronic HIV

  13. [Mechanisms of coronary flow recovery in the isolated heart during reperfusion with cardioprotective liposomal emoxipin form]. (United States)

    Toropova, Ia G; Antonova, L V; Mukhamadiiarov, R A; Bogdanov, M V; Golovkin, A S


    In the experiments on the isolated perfused rat heart the effects of liposomes, containing different concentrations (0.25 and 0.1 mg/mL) of emoxipine, on coronary flow restoration after total normothermic ischemia and reperfusion were studied. The coronary flow, levels of nitrates and nitrites in the outflowing perfusate from heart and level of free radical processes were assessed, The obtained results showed that 0.1 mg/mL liposomal emoxipine provide with stronger increase coronary flow during reperfusion mostly due to the increase concentration of endothelial nitric oxide compare with treatments at 0.25 mg/mL.

  14. Spinal Cord Blood Flow after Ischemic Preconditioning in a Rat Model of Spinal Cord Ischemia

    Directory of Open Access Journals (Sweden)

    David Zvara


    Full Text Available Spinal cord blood flow after ischemic preconditioning is poorly characterized. This study is designed to evaluate spinal cord blood flow patterns in animals after acute ischemic preconditioning. Experiment 1: After a laminectomy and placement of a laser Doppler probe over the lumbar spinal cord to measure spinal cord blood flow, 16 male Sprague-Dawley rats were randomized into two groups: ischemic preconditioning (IPC, n = 8, and control (CTRL, n = 8. Rats in the CTRL and the IPC groups were subjected to 12 min of ischemia directly followed by 60 min of reperfusion. IPC rats received 3 min of IPC and 30 min of reperfusion prior to the 12-min insult period. Experiment 2: After instrumentation, the rats were randomized into three groups: control (CTRL, n = 7, ischemic preconditioning (IPC, n = 7, and time control (TC, n = 4. Rats in the CTRL and the IPC groups were subjected to the same ischemia and reperfusion protocol as above. The TC group was anesthetized for the same time period as the CTRL and the IPC groups, but had no ischemic intervention. Microspheres were injected at baseline and at 15 and 60 min into the final reperfusion. All rats were euthanized and tissue harvested for spinal cord blood flow analysis. In Experiment 1, there was a slight, significant difference in spinal cord blood flow during the ischemic period; however, this difference soon disappeared during reperfusion. In experiment 2, there was no difference in blood flow at any experimental time. The results of these experiments demonstrate that IPC slightly enhances blood flow to the spinal cord during ischemia; however, this effect is not sustained during the reperfusion period.

  15. Local Control of Blood Flow (United States)

    Clifford, Philip S.


    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…

  16. Blood Flow in the Microcirculation (United States)

    Secomb, Timothy W.


    The microcirculation is an extensive network of microvessels that distributes blood flow throughout living tissues. Reynolds numbers are much less than 1, and the equations of Stokes flow apply. Blood is a suspension of cells with dimensions comparable to microvessel diameters. Highly deformable red blood cells, which transport oxygen, have a volume concentration (hematocrit) of 40–45% in humans. In the narrowest capillaries, these cells move in single file with a surrounding lubricating layer of plasma. In larger vessels, the red blood cells migrate toward the centerline, reducing the resistance to blood flow. Vessel walls are coated with a layer of macromolecules that restricts flow. At diverging bifurcations, hematocrit is not evenly distributed in the downstream vessels. Other particles are driven toward the walls by interactions with red blood cells. These physiologically important phenomena are discussed here from a fluid mechanical perspective.

  17. Holographic laser Doppler imaging of pulsatile blood flow

    CERN Document Server

    Bencteux, Jeffrey; Kostas, Thomas; Bayat, Sam; Atlan, Michael


    We report on wide-field imaging of pulsatile motion induced by blood flow using heterodyne holographic interferometry on the thumb of a healthy volunteer, in real-time. Optical Doppler images were measured with green laser light by a frequency-shifted Mach-Zehnder interferometer in off-axis configuration. The recorded optical signal was linked to local instantaneous out-of-plane motion of the skin at velocities of a few hundreds of microns per second, and compared to blood pulse monitored by plethysmoraphy during an occlusion-reperfusion experiment.

  18. Endovascular blood flow measurement system (United States)

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


    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.

  19. Neuromodulation of cerebral blood flow

    NARCIS (Netherlands)

    ter Laan, Mark


    Dit proefschrift behandelt de modulatie van de cerebrale doorbloeding (cerebral blood flow, CBF) door cervicale elektrische stimulatie en de aanname dat het sympathisch zenuwstelsel hierin een specifieke rol speelt. Enkele resultaten met cervicale ruggenmergsstimulatie (spinal cord stimulation, SCS)

  20. Hyperhomocysteinemia decreases bone blood flow

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    Neetu T


    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

  1. Chaotic advection in blood flow. (United States)

    Schelin, A B; Károlyi, Gy; de Moura, A P S; Booth, N A; Grebogi, C


    In this paper we argue that the effects of irregular chaotic motion of particles transported by blood can play a major role in the development of serious circulatory diseases. Vessel wall irregularities modify the flow field, changing in a nontrivial way the transport and activation of biochemically active particles. We argue that blood particle transport is often chaotic in realistic physiological conditions. We also argue that this chaotic behavior of the flow has crucial consequences for the dynamics of important processes in the blood, such as the activation of platelets which are involved in the thrombus formation.

  2. Magnetohydrodynamics of blood flow. (United States)

    Keltner, J R; Roos, M S; Brakeman, P R; Budinger, T F


    The changes in hydrostatic pressure and electrical potentials across vessels in the human vasculature in the presence of a large static magnetic field are estimated to determine the feasibility of in vivo NMR spectroscopy at fields as high as 10 T.A 10-T magnetic field changes the vascular pressure in a model of the human vasculature by less than 0.2%. An exact solution to the magnetohydrodynamic equations describing a conducting fluid flowing transverse to a static magnetic field in a nonconducting, straight, circular tube is used. This solution is compared to an approximate solution that assumes that no magnetic fields are induced in the fluid and that has led previous investigators to predict significant biological effects from static magnetic fields. Experimental results show that the exact solution accurately predicts the magnetohydrodynamic slowing of 15% NaCl flowing transverse to 2.3- and 4.7-T magnetic fields for fluxes below 0.5 liter/min while the approximate solution predicts a much more retarded flow.

  3. Hyperglycemia is an important predictor of impaired coronary flow before reperfusion therapy in ST-segment elevation myocardial infarction

    NARCIS (Netherlands)

    Timmer, [No Value; Ottervanger, JP; de Boer, MJ; Hoorntje, JCA; Gosselink, ATM; Suryapranata, H; Zijlstra, F; van't Hof, AWJ; Dambrink, Jan Hendrik Everwijn


    OBJECTIVES This study was designed to investigate whether elevated glucose is associated with impaired Thrombolysis In Myocardial Infarction (TIMI) flow before primary percutaneous coronary intervention (PCI). BACKGROUND Reperfusion before primary PCI in patients with ST-segment elevation myocardial

  4. Cerebral blood-flow tomography

    DEFF Research Database (Denmark)

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


    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....

  5. Matrix metalloproteinase-9 expression and blood brain barrier permeability in the rat brain after cerebral ischemia/reperfusion injury

    Institute of Scientific and Technical Information of China (English)

    Lifang Lei; Xiaohong Zi; Qiuyun Tu


    BACKGROUND: The integrity of the blood brain barrier (BBB) plays an important role in the patho-physiological process of cerebral ischemia/reperfusion injury. It has been recently observed that metalloproteinase-9 (MMP-9) is closely related to cerebral ischemia/reperfusion injuryOBJECTIVE: This study was designed to observe MMP-9 expression in the rat brain after cerebral ischemia/reperfusion injury and to investigate its correlation to BBB permeability.DESIGN, TIME AND SETTING: This study, a randomized controlled animal experiment, was performed at the Institute of Neurobiology, Central South University between September 2005 and March 2006.MATERIALS: Ninety healthy male SD rats, aged 3-4 months, weighing 200-280g, were used in the present study. Rabbit anti-rat MMP-9 polyclonal antibody (Boster, Wuhan, China) and Evans blue (Sigma, USA) were also used.METHODS: All rats were randomly divided into 9 groups with 10 rats in each group: normal control group, sham-operated group, and ischemia for 2 hours followed by reperfusion for 3,6,12 hours, 1,2,4 and 7 days groups. In the ischemia/reperfusion groups, rats were subjected to ischemia/reperfusion injury by suture occlusion of the right middle cerebral artery. In the sham-operated group, rats were merely subjected to vessel dissociation. In the normal control group, rats were not modeled.MAIN OUTCOME MEASURES: BBB permeability was assessed by determining the level of effusion of Evans blue. MMP-9 expression was detected by an immunohistochemical method.RESULTS: All 90 rats were included in the final analysis. BBB permeability alteration was closely correlated to ischemia/reperfusion time. BBB permeability began to increase at ischemia/reperfusion for 3 hours, then it gradually reached a peak level at ischemia/reperfusion for 1 day, and thereafter it gradually decreased. MMP-9 expression began to increase at ischemia/reperfusion for 3 hours, then gradually reached its peak level 2 days after perfusion, and thereafter

  6. Ocular Blood Flow Autoregulation Mechanisms and Methods

    Directory of Open Access Journals (Sweden)

    Xue Luo


    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.

  7. Ocular Blood Flow Autoregulation Mechanisms and Methods


    Xue Luo; Yu-meng Shen; Meng-nan Jiang; Xiang-feng Lou; Yin Shen


    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 va...

  8. Preventive administration of cromakalim reduces aquaporin-4 expression and blood-brain barrier permeability in a rat model of cerebral ischemia/reperfusion injury

    Institute of Scientific and Technical Information of China (English)

    Shilei Wang; Yanting Wang; Yan Jiang; Qingxian Chang; Peng Wang; Shiduan Wang


    Cromakalim, an adenosine triphosphate-sensitive potassium channel opener, exhibits protective effects on cerebral ischemia/reperfusion injury. However, there is controversy as to whether this effect is associated with aquaporin-4 and blood-brain barrier permeability. Immunohistochemistry results show that preventive administration of cromakalim decreased aquaporin-4 and IgG protein expression in rats with ischemia/reperfusion injury; it also reduced blood-brain barrier permeability, and alleviated brain edema, ultimately providing neuroprotection.

  9. YiQiFuMai powder injection ameliorates blood-brain barrier dysfunction and brain edema after focal cerebral ischemia-reperfusion injury in mice. (United States)

    Cao, Guosheng; Ye, Xinyi; Xu, Yingqiong; Yin, Mingzhu; Chen, Honglin; Kou, Junping; Yu, Boyang


    YiQiFuMai powder injection (YQFM) is a modern preparation derived from the traditional Chinese medicine Sheng-Mai-San. YQFM is widely used in clinical practice in the People's Republic of China, mainly for the treatment of microcirculatory disturbance-related diseases. However, little is known about its role in animals with ischemic stroke. The aim of this study was to examine the effect of YQFM on brain edema and blood-brain barrier (BBB) dysfunction induced by cerebral ischemia-reperfusion (I/R) injury. Male C57BL/6J mice underwent right middle cerebral artery occlusion for 1 hour with a subsequent 24-hour reperfusion to produce I/R injury. YQFM (three doses: 0.336, 0.671, and 1.342 g/kg) was then given intraperitoneally (IP). The results demonstrated that YQFM significantly decreased infarct size, improved neurological deficits, reduced brain water content, and increased cerebral blood flow after I/R injury. 18F-fluorodeoxyglucose micro-positron emission tomography imaging and hematoxylin and eosin staining results indicated that YQFM is able to ameliorate brain metabolism and histopathological damage after I/R. Moreover, YQFM administration reduced BBB leakage and upregulated the expression of zona occludens-1 (ZO-1) and occludin, which was confirmed by Evans Blue extravasation, Western blotting, and immunofluorescence assay. Our findings suggest that YQFM provides protection against focal cerebral I/R injury in mice, possibly by improving BBB dysfunction via upregulation of the expression of tight junction proteins.

  10. Quantitative Cerebral Blood Flow Measurements Using MRI


    Muir, Eric R; Watts, Lora Talley; Tiwari, Yash Vardhan; Bresnen, Andrew; Timothy Q Duong


    Magnetic resonance imaging utilized as a quantitative and noninvasive method to image cerebral blood flow. The two most common techniques used to detect cerebral blood flow are dynamic susceptibility contrast (DSC) perfusion MRI and arterial spin labeling perfusion MRI. Herein we describe the use of these two techniques to measure cerebral blood flow in rodents, including methods, analysis, and important considerations when utilizing these techniques.

  11. Stimulation of the sphenopalatine ganglion induces reperfusion and blood-brain barrier protection in the photothrombotic stroke model.

    Directory of Open Access Journals (Sweden)

    Haviv Levi

    Full Text Available PURPOSE: The treatment of stroke remains a challenge. Animal studies showing that electrical stimulation of the sphenopalatine ganglion (SPG exerts beneficial effects in the treatment of stroke have led to the initiation of clinical studies. However, the detailed effects of SPG stimulation on the injured brain are not known. METHODS: The effect of acute SPG stimulation was studied by direct vascular imaging, fluorescent angiography and laser Doppler flowmetry in the sensory motor cortex of the anaesthetized rat. Focal cerebral ischemia was induced by the rose bengal (RB photothrombosis method. In chronic experiments, SPG stimulation, starting 15 min or 24 h after photothrombosis, was given for 3 h per day on four consecutive days. Structural damage was assessed using histological and immunohistochemical methods. Cortical functions were assessed by quantitative analysis of epidural electro-corticographic (ECoG activity continuously recorded in behaving animals. RESULTS: Stimulation induced intensity- and duration-dependent vasodilation and increased cerebral blood flow in both healthy and photothrombotic brains. In SPG-stimulated rats both blood brain-barrier (BBB opening, pathological brain activity and lesion volume were attenuated compared to untreated stroke animals, with no apparent difference in the glial response surrounding the necrotic lesion. CONCLUSION: SPG-stimulation in rats induces vasodilation of cortical arterioles, partial reperfusion of the ischemic lesion, and normalization of brain functions with reduced BBB dysfunction and stroke volume. These findings support the potential therapeutic effect of SPG stimulation in focal cerebral ischemia even when applied 24 h after stroke onset and thus may extend the therapeutic window of currently administered stroke medications.

  12. Regional cerebral blood flow in schizophrenia

    Energy Technology Data Exchange (ETDEWEB)

    Mathew, R.J.; Duncan, G.C.; Weinman, M.L.; Barr, D.L.


    Regional cerebral blood flow (rCBF) was measured via xenon133 inhalation technique in 23 patients with schizophrenia and 18 age- and sex-matched controls. The mean blood flow to both hemispheres was found to be lower for the patients. The patients and their controls did not differ on interhemispheric differences in blood flow. There were no differences in rCBF between medicated and unmedicated, subchronic and chronic, and paranoid and nonparanoid patients. Hallucinations were associated with reduced blood flow to several postcentral regions.

  13. Improvement of regional myocardial blood flow and function and reduction of infarct size with ivabradine: protection beyond heart rate reduction. (United States)

    Heusch, Gerd; Skyschally, Andreas; Gres, Petra; van Caster, Patrick; Schilawa, Dustin; Schulz, Rainer


    Effects of the bradycardic agent ivabradine on regional blood flow, contractile function, and infarct size were studied in a pig model of myocardial ischaemia/reperfusion. Heart rate reduction by beta-blockade is associated with negative inotropism and unmasked alpha-adrenergic coronary vasoconstriction. Ivabradine is the only available bradycardic agent for clinical use. Anaesthetized pigs were subjected to 90 min controlled left anterior descending coronary artery hypoperfusion and 120 min reperfusion. Regional blood flow was measured with microspheres, regional function with sonomicrometry, and infarct size with triphenyl tetrazolium chloride staining. Pigs received placebo or ivabradine (0.6 mg/kg i.v.) before or during ischaemia or before reperfusion, respectively. Pre-treatment with ivabradine reduced infarct size from 35 +/- 4 (SEM) to 19 +/- 4% of area at risk (AAR). Ivabradine 15-20 min after the onset of ischaemia increased regional myocardial blood flow from 2.12 +/- 0.31 to 3.55 +/- 0.56 microL/beat/g and systolic wall thickening from 6.7 +/- 1.0 to 16.3 +/- 3.0%; infarct size was reduced from 12 +/- 4 to 2 +/- 1% of AAR. Ivabradine 5 min before reperfusion still reduced infarct size from 36 +/- 4 to 21 +/- 5% of AAR. The benefit of ivabradine on flow and function was eliminated by atrial pacing, but part of the reduction of infarct size by ivabradine was not. Ivabradine's protection goes beyond heart rate reduction.

  14. L-propionylcarnitine increases postischemic blood flow but does not affect recovery of energy charge. (United States)

    Sassen, L M; Bezstarosti, K; Van der Giessen, W J; Lamers, J M; Verdouw, P D


    Effects of pretreatment with L-propionylcarnitine (50 mg/kg, n = 9) or saline (n = 10) were studied in open-chest anesthetized pigs, in which ischemia was induced by decreasing left anterior descending coronary artery blood flow to 20% of baseline. After 60 min of ischemia, myocardium was reperfused for 2 h. In both groups, flow reduction abolished contractile function of the affected myocardium and caused similar decreases in ATP (by 55%) and energy charge [(ATP + 0.5ADP)/(ATP + ADP + AMP); decrease from 0.91 to 0.60], mean arterial blood pressure (by 10-24%), the maximum rate of rise in left ventricular pressure (by 26-32%), and cardiac output (by 20-30%). During reperfusion, "no-reflow" was attenuated by L-propionylcarnitine, because myocardial blood flow returned to 61 and 82% of baseline in the saline- and L-propionylcarnitine-treated animals, respectively. Cardiac output of the saline-treated animals further decreased (to 52% of baseline), and systemic vascular resistance increased from 46 +/- 3 to 61 +/- 9 mmHg.min.l-1, thereby maintaining arterial blood pressure. In L-propionylcarnitine-treated pigs, cardiac output remained at 75% of baseline, and systemic vascular resistance decreased from 42 +/- 3 to 38 +/- 4 mmHg.min.l-1. In both groups, energy charge but not the ATP level of the ischemic-reperfused myocardium tended to recover, whereas the creatine phosphate level showed significantly more recovery in saline-treated animals. We conclude that L-propionylcarnitine partially preserved vascular patency in ischemic-reperfused porcine myocardium but had no immediate effect on "myocardial stunning." Potential markers for long-term recovery were not affected by L-propionylcarnitine.

  15. Pancreatic islet blood flow and its measurement. (United States)

    Jansson, Leif; Barbu, Andreea; Bodin, Birgitta; Drott, Carl Johan; Espes, Daniel; Gao, Xiang; Grapensparr, Liza; Källskog, Örjan; Lau, Joey; Liljebäck, Hanna; Palm, Fredrik; Quach, My; Sandberg, Monica; Strömberg, Victoria; Ullsten, Sara; Carlsson, Per-Ola


    Pancreatic islets are richly vascularized, and islet blood vessels are uniquely adapted to maintain and support the internal milieu of the islets favoring normal endocrine function. Islet blood flow is normally very high compared with that to the exocrine pancreas and is autonomously regulated through complex interactions between the nervous system, metabolites from insulin secreting β-cells, endothelium-derived mediators, and hormones. The islet blood flow is normally coupled to the needs for insulin release and is usually disturbed during glucose intolerance and overt diabetes. The present review provides a brief background on islet vascular function and especially focuses on available techniques to measure islet blood perfusion. The gold standard for islet blood flow measurements in experimental animals is the microsphere technique, and its advantages and disadvantages will be discussed. In humans there are still no methods to measure islet blood flow selectively, but new developments in radiological techniques hold great hopes for the future.

  16. Ciliary Blood Flow and Aqueous Humor Production (United States)

    Kiel, J.W.; Hollingsworth, M.; Rao, R.; Chen, M.; Reitsamer, H.A.


    Aqueous humor production is a metabolically active process sustained by the delivery of oxygen and nutrients and removal of metabolic waste by the ciliary circulation. This article describes our investigations into the relationship between ciliary blood flow and aqueous humor production. The results presented indicate that there is a dynamic relationship between ciliary blood flow and aqueous humor production, with production being blood flow independent above a critical level of perfusion, and blood flow dependent below it. The results also show that the plateau portion of the relationship shifts up or down depending on the level of secretory stimulation or inhibition, and that oxygen is one critical factor provided by ciliary blood flow. Also presented is a theoretical model of ocular hydrodynamics incorporating these new findings. PMID:20801226

  17. Endomorphins and β-Endorphin Do Not Affect Heart Tolerance to the Pathogenic Effect of Reperfusion. (United States)

    Mukhomedzyanov, A V; Maslov, L N; Tsibulnikov, S Yu; Pei, J M


    Selective agonists of μ1- and μ2-opioid receptors endomorphin-2 and endomorphin-1 injected intravenously in a dose of 4500 nmol/kg in 5 min before coronary blood flow resumption had no effect on cardiac reperfusion damage. Consequently, μ1- and μ2-opioid receptors are not involved in the regulation of heart tolerance to reperfusion injury. Nonselective opioid receptor agonist β-endorphin (100 nmol/kg) also did not affect heart tolerance to the pathogenic effect of reperfusion.

  18. The Physics of Coronary Blood Flow

    CERN Document Server

    Zamir, M


    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...

  19. Mechanics of blood flow in the microcirculation. (United States)

    Secomb, T W


    The microcirculation in most tissues consists of an intricate network of very narrow tubes. In analyses of blood flow through the microcirculation, inertial effects can be neglected, but continuum models for blood cannot be assumed, since blood is a concentrated suspension of cells with dimensions comparable to vessel diameters. These cells strongly influence blood flow. About 45% of blood volume consists of red blood cells, whose key mechanical properties are known. A red cell has a fluid interior, surrounded by a flexible membrane, which strongly resists area changes, but bends and shears easily. White blood cells are comparable in size but much less numerous. They are less flexible than red cells and capable of active locomotion. Other suspended elements are much smaller than red cells: This review focuses on the mechanics of red cell motion in the microcirculation. Experimental and theoretical studies of blood flow in uniform tubes, bifurcations and networks are discussed. Comparisons between predicted and observed flows in networks imply that resistance to blood flow in living microvessels is higher than that in uniform tubes with corresponding diameters. Living microvessels have non-uniform geometries, and red cells must deform continually to traverse them. Theoretical results are presented implying that these transient deformations contribute to increased flow resistance in the microcirculation.

  20. Blood flow autoregulation in pedicled flaps

    DEFF Research Database (Denmark)

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


    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...

  1. Targeting reperfusion injury in the era of primary percutaneous coronary intervention

    DEFF Research Database (Denmark)

    Lønborg, Jacob Thomsen


    Introduction of reperfusion therapy by primary percutaneous coronary intervention (PCI) has resulted in improved outcomes for patients presenting with ST-segment elevation myocardial infarction. Despite the obvious advantages of primary PCI, acute restoration of blood flow paradoxically also...

  2. Carbon dioxide and liver blood flow. (United States)

    Dutton, R; Levitzky, M; Berkman, R


    This study was designed to determine blood flow to the liver during hypercapnia and combined hypercapnia-hypoxia with the portal vein and hepatic artery intact except for placement of an electromagnetic flow probe around these vessels. Twenty mongrel dogs weighing 30-45 kg were anesthetized with pentobarbital and flow probes and occluders were surgically implanted. Ten of these dogs were subjected to hypercapnia alone. During inspiration of 6% CO2 in room air, portal vein flow increased from 588 +/- 73 ml/min to 731 +/- 113 ml/min (p less than .05), while hepatic artery flow did not change significantly from its control mean of 221 +/- 38 ml/min. In the remaining dogs, inhalation of 6% O2 resulted in a reduction of portal blood flow within 30 min from 527 +/- 55 ml/min to 381 +/- 41 ml/min (p less than .01). Again, mean hepatic artery flow did not increase significantly above its control of 273 +/- 43 ml/min. Subsequent inhalation of 6% CO2 plus 6% O2 (combined hypercapniahypoxia) for 30 min in these same animals resulted in a significant increase of portal vein blood flow from 514 +/- 46 ml/min to 716 +/- 116 ml/min (p less than .05). Thus, hypercapnia alone increases total liver blood flow, primarily by an increase in portal vein flow. Hypoxia results in a decrease in portal vein flow. The superimposition of hypercapnia on hypoxia restores blood flow to a level close to that found with hypercapnia alone. Hypercapnia in the range of 63 +/- 4 mmHg PCO2 overwhelms the tendency toward a reduction of portal vein blood flow induced by an arterial PO2 of 42 +/- 5 mmHg in the presence of mild hypocapnia (PCO2 : 30.2 +/- 1 mmHg).

  3. Bone blood flow and metabolism in humans

    DEFF Research Database (Denmark)

    Heinonen, Ilkka; Kemppainen, Jukka; Kaskinoro, Kimmo


    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...... leg. In conclusion, resting femoral bone blood flow increases by physical exercise, but appears to level off with increasing exercise intensities. Moreover, while moderate systemic hypoxia does not change bone blood flow at rest or during exercise, intra-arterially administered adenosine during...

  4. The protective effect of HET0016 on brain edema and blood-brain barrier dysfunction after cerebral ischemia/reperfusion. (United States)

    Liu, Yu; Wang, Di; Wang, Huan; Qu, Youyang; Xiao, Xingjun; Zhu, Yulan


    N-hydroxy-N-(4-butyl-2-methylphenyl) formamidine (HET0016) is a specific 20-hydroxyeicosatetraenoic acid (20-HETE) inhibitor which was first synthesized in 2001. It has been demonstrated that HET0016 reduces cerebral infarction volume in rat middle cerebral artery occlusion (MCAO) models. However, little is known about the role of HET0016 in the blood-brain barrier (BBB) dysfunction after cerebral ischemia/reperfusion (I/R) injury. The present study was designed to examine the effect of HET0016 in a MCAO and reperfusion rat model to determine whether it protects against brain edema and BBB disruption. Rats were subjected to 90 min MCAO, followed by 4, 24, 48, and 72 h reperfusion. Brain edema was measured according to the wet and dry weight method. BBB permeability based on the extravasation of Evans blue and sodium fluorescein was detected. BBB ultrastructure alterations were presented through transmission electron microscope. Superoxide production in ischemic tissue was also measured by dihydroethidium fluorescent probe. Western blot was used to analyze the expression of Claudin-5, ZO-1, MMP-9, and JNK pathway. At 24h after reperfusion, HET0016 reduced brain edema and BBB leakage. Ultrastructural damage of BBB and the increase of superoxide production were attenuated by HET0016 treatment. Western blot showed that HET0016 suppressed the activation of MMP-9 and JNK pathway but restored the expression of Claudin-5 and ZO-1. In conclusion, these results suggest that HET0016 protects BBB dysfunction after I/R by regulating the expression of MMP-9 and tight junction proteins. Furthermore, inhibition of oxidative stress and JNK pathway may be involved in this protecting effect.

  5. Brachial blood flow under relative levels of blood flow restriction is decreased in a nonlinear fashion. (United States)

    Mouser, J Grant; Ade, Carl J; Black, Christopher D; Bemben, Debra A; Bemben, Michael G


    Blood flow restriction (BFR), the application of external pressure to occlude venous return and restrict arterial inflow, has been shown to increase muscular size and strength when combined with low-load resistance exercise. BFR in the research setting uses a wide range of pressures, applying a pressure based upon an individual's systolic pressure or a percentage of occlusion pressure; not a directly determined reduction in blood flow. The relationship between relative pressure and blood flow has not been established. To measure blood flow in the arm under relative levels of BFR. Forty-five people (18-40 years old) participated. Arterial occlusion pressure in the right arm was measured using a 5-cm pneumatic cuff. Blood flow in the brachial artery was measured at rest and at pressures between 10% and 90% of occlusion using ultrasound. Blood flow decreased in a nonlinear, stepped fashion. Blood flow decreased at 10% of occlusion and remained constant until decreasing again at 40%, where it remained until 90% of occlusion. The decrease in brachial blood flow is not proportional to the applied relative pressure. The prescription of blood flow restriction should take into account the stimulus provided at each relative level of blood flow. © 2017 Scandinavian Society of Clinical Physiology and Nuclear Medicine. Published by John Wiley & Sons Ltd.

  6. Regulation of blood flow by prostaglandins

    DEFF Research Database (Denmark)

    Boushel, Robert Christopher; Langberg, H; Risum, N;


    adaptation of connective tissues e.g. tendon. This review covers the role of PG for mediating tissue blood flow at rest and during increases in metabolic demand such as exercise and reactive hyperaemia. There is strong evidence that PGs contribute to elevate blood flow at rest and during reactive hyperaemia...... in a variety of tissues. Their role for regulating the large increases in muscle blood flow during exercise is less clear which may be explained by redundant mechanisms. Several interactions are known to exist between specific vasodilator substances, and therefore PGs can act in synergy with other substances...... and contribute to functional hyperaemia. Furthermore, there is evidence for differential, tissue-specific influences of PGs where their influence on blood flow during exercise may be profound....

  7. Blood flow and permeability in microvessels (United States)

    Sugihara-Seki, Masako; Fu, Bingmei M.


    The mechanics of blood flow in microvessels and microvessel permeability are reviewed. In the first part, characteristics of blood flow in vivo and in vitro are described from a fluid-mechanical point of view, and mathematical models for blood flow in microvessels are presented. Possible causes of the increased flow resistance obtained in vivo compared to in vitro are examined, including the effects of irregularities of vessel lumen, the presence of endothelial surface glycocalyx and white blood cells. In the second part, the ultrastructural pathways and mechanisms whereby endothelial cells and the clefts between the cells modulate microvessel permeability to water and solutes are introduced. Previous and current models for microvessel permeability to water and solutes are reviewed. These models examine the role of structural components of interendothelial cleft, such as junction strands and surface glycocalyx, in the determination of water and solute transport across the microvessel walls. Transport models in the tissue space surrounding the microvessel are also described.

  8. Clinical relevance of intermittent tumour blood flow

    Energy Technology Data Exchange (ETDEWEB)

    Durand, Ralph E.; Aquino-Parsons, Christina [British Columbia Cancer Research Centre, Vancouver (Canada)


    One of the goals of translational cancer research is to understand basic 'phenomena' so that tumour response to therapy can be improved. One such phenomenon is intermittent tumour blood flow. The impact of the transient hypoxia that results from decreased tumour blood flow is now beginning to be appreciated in preclinical systems, and also receiving some attention in clinical practise. Thus in this article we review the nature and frequency of microregional blood flow changes in preclinical and clinical tumours and examine the impact of those changes on response to both radiotherapy and chemotherapy. Additionally, the implications of non-constant blood flow for both the growth of the unperturbed tumour and the regrowth of surviving tumour clonogens during and after therapy are examined.

  9. Frequency encoding in renal blood flow regulation

    DEFF Research Database (Denmark)

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


    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 the myogenic oscillation by TGF. Analysis by wavelet transforms of single-nephron blood flow confirms that both amplitude and frequency of the myogenic oscillation are modulated by TGF. We developed a double-wavelet transform technique to estimate modulation frequency. Median value of the ratio of modulation...... TGF cycle to the next. We used a blood pressure signal recorded by telemetry from a conscious rat as the input to the model. Blood pressure fluctuations induced variability in the modulation records similar to those found in the nephron blood flow results. Frequency and amplitude modulation can...

  10. Ischemia reperfusion injury, ischemic conditioning and diabetes mellitus. (United States)

    Lejay, Anne; Fang, Fei; John, Rohan; Van, Julie A D; Barr, Meredith; Thaveau, Fabien; Chakfe, Nabil; Geny, Bernard; Scholey, James W


    Ischemia/reperfusion, which is characterized by deficient oxygen supply and subsequent restoration of blood flow, can cause irreversible damages to tissue. Mechanisms contributing to the pathogenesis of ischemia reperfusion injury are complex, multifactorial and highly integrated. Extensive research has focused on increasing organ tolerance to ischemia reperfusion injury, especially through the use of ischemic conditioning strategies. Of morbidities that potentially compromise the protective mechanisms of the heart, diabetes mellitus appears primarily important to study. Diabetes mellitus increases myocardial susceptibility to ischemia reperfusion injury and also modifies myocardial responses to ischemic conditioning strategies by disruption of intracellular signaling responsible for enhancement of resistance to cell death. The purpose of this review is twofold: first, to summarize mechanisms underlying ischemia reperfusion injury and the signal transduction pathways underlying ischemic conditioning cardioprotection; and second, to focus on diabetes mellitus and mechanisms that may be responsible for the lack of effect of ischemic conditioning strategies in diabetes.

  11. Establishing the flow cytometric assessment of myeloid cells in kidney ischemia/reperfusion injury. (United States)

    Williams, Timothy M; Wise, Andrea F; Alikhan, Maliha A; Layton, Daniel S; Ricardo, Sharon D


    Polychromatic flow cytometry is a powerful tool for assessing populations of cells in the kidney through times of homeostasis, disease and tissue remodeling. In particular, macrophages have been identified as having central roles in these three settings. However, because of the plasticity of myeloid cells it has been difficult to define a specific immunophenotype for these cells in the kidney. This study developed a gating strategy for identifying and assessing monocyte and macrophage subpopulations, along with neutrophils and epithelial cells in the healthy kidney and following ischemia/reperfusion (IR) injury in mice, using antibodies against CD45, CD11b, CD11c, Ly6C, Ly6G, F4/80, CSF-1R (CD115), MHC class II, mannose receptor (MR or CD206), an alternatively activated macrophage marker, and the epithelial cell adhesion marker (EpCAM or CD326). Backgating analysis and assessment of autofluorescence was used to extend the knowledge of various cell types and the changes that occur in the kidney at various time-points post-IR injury. In addition, the impact of enzymatic digestion of kidneys on cell surface markers and cell viability was assessed. Comparisons of kidney myeloid populations were also made with those in the spleen. These results provide a useful reference for future analyses of therapies aimed at modulating inflammation and enhancing endogenous remodeling following kidney injury.

  12. Cerebral blood flow response to functional activation

    DEFF Research Database (Denmark)

    Paulson, Olaf B; Hasselbalch, Steen G; Rostrup, Egill


    Cerebral blood flow (CBF) and cerebral metabolic rate are normally coupled, that is an increase in metabolic demand will lead to an increase in flow. However, during functional activation, CBF and glucose metabolism remain coupled as they increase in proportion, whereas oxygen metabolism only...

  13. 21 CFR 870.2120 - Extravascular blood flow probe. (United States)


    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Extravascular blood flow probe. 870.2120 Section... 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...

  14. 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;


    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...... arterial blood pressure by 49% and decreased TRBF by 12%, providing an increase in renal vascular resistance of 69%. Dynamic analysis showed autoregulation of renal blood flow in the frequency range ... of TRBF by aortic blood flow subtraction is a practical and reliable method that allows direct comparison of excretory function and renal blood flow from two kidneys. The method also allows direct comparison between TRBF and flow in the caudal aorta....

  15. An implantable blood pressure and flow transmitter. (United States)

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


    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.


    Institute of Scientific and Technical Information of China (English)

    WEI Lan; WEN Gong-bi; TAN Wen-chang


    A numerical analysis of the steady/pulsatile flow and macromolecular (such as LDL and Albumin) transport in curved blood vessels was carried out. The computational results predict that the vortex of the secondary flow is time-dependent in the aortic arch.The concentration of macromolecule concentrates at the region of sharp curve, and the wall concentration at the outer part is higher than that at the inner part. Atherosclerosis and thrombosis are prone to develop in such regions with sharp flow.

  17. Cerebral blood flow in the neonate. (United States)

    Vutskits, Laszlo


    Ensuring adequate oxygenation of the developing brain is the cornerstone of neonatal critical care. Despite decades of clinical research dedicated to this issue of paramount importance, our knowledge and understanding regarding the physiology and pathophysiology of neonatal cerebral blood flow are still rudimentary. This review primarily focuses on currently available human clinical and experimental data on cerebral blood flow and autoregulation in the preterm and term infant. Limitations of systemic blood pressure values as surrogates for monitoring adequate cerebral oxygen delivery are discussed. Particular emphasis is placed on the high interindividual variability in cerebral blood flow values, vasoreactivity, and autoregulatory thresholds making the applications of normative values highly questionable. Technical and ethical difficulties to conduct such trials leave us with a near complete lack of knowledge on how pharmacological and surgical interventions impact on cerebral autoregulation. The ensemble of these works argues for the necessity of highly individualized care by taking advantage of continuous bedside monitoring of cerebral circulation. They also point to the urgent need for further studies addressing the exciting but difficult issue of cerebral blood flow autoregulation in the neonate.

  18. Blood flow characteristics in the aortic arch (United States)

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


    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.

  19. Methylophiopogonanone A Protects against Cerebral Ischemia/Reperfusion Injury and Attenuates Blood-Brain Barrier Disruption In Vitro.

    Directory of Open Access Journals (Sweden)

    Mingbao Lin

    Full Text Available Methylophiopogonanone A (MO-A, an active homoisoflavonoid of the Chinese herb Ophiopogon japonicus which has been shown to have protective effects on cerebral ischemia/reperfusion (I/R injury, has been demonstrated to have anti-inflammatory and anti-oxidative properties. However, little is known about its role in cerebral I/R injury. Therefore, in this study, by using a middle cerebral artery occlusion (MCAO and reperfusion rat model, the effect of MO-A on cerebral I/R injury was examined. The results showed that MO-A treatment reduced infarct volume and brain edema, improved neurological deficit scores, reversed animal body weight decreases, and increased animal survival time in the stroke groups. Western blotting showed that MO-A suppressed MMP-9, but restored the expression of claudin-3 and claudin-5. Furthermore, transmission electron microscopy were monitored to determine the blood-brain barrier (BBB alterations in vitro. The results showed that MO-A markedly attenuated BBB damage in vitro. Additionally, MO-A inhibited ROS production in ECs and MMP-9 release in differentiated THP-1 cells in vitro, and suppressed ICAM-1 and VCAM-1 expression in ECs and leukocyte/EC adhesion. In conclusion, our data indicate that MO-A has therapeutic potential against cerebral I/R injury through its ability to attenuate BBB disruption by regulating the expression of MMP-9 and tight junction proteins.

  20. Whole blood transcriptomics in cardiac surgery identifies a gene regulatory network connecting ischemia reperfusion with systemic inflammation.

    Directory of Open Access Journals (Sweden)

    Orfeas Liangos

    Full Text Available BACKGROUND: Cardiac surgery with cardiopulmonary bypass (CS/CPB is associated with increased risk for postoperative complications causing substantial morbidity and mortality. To identify the molecular mechanisms underlying CS/CPB-induced pathophysiology we employed an integrative systems biology approach using the whole blood transcriptome as the sentinel organ. METHODOLOGY/PRINCIPAL FINDINGS: Total RNA was isolated and globin mRNA depleted from whole blood samples prospectively collected from 10 patients at time points prior (0, 2 and 24 hours following CS/CPB. Genome-wide transcriptional analysis revealed differential expression of 610 genes after CS/CPB (p<0.01. Among the 375 CS/CPB-upregulated genes, we found a gene-regulatory network consisting of 50 genes, reminiscent of activation of a coordinated genetic program triggered by CS/CPB. Intriguingly, the highly connected hub nodes of the identified network included key sensors of ischemia-reperfusion (HIF-1alpha and C/EBPbeta. Activation of this network initiated a concerted inflammatory response via upregulation of TLR-4/5, IL1R2/IL1RAP, IL6, IL18/IL18R1/IL18RAP, MMP9, HGF/HGFR, CalgranulinA/B, and coagulation factors F5/F12 among others. Differential regulation of 13 candidate genes including novel, not hitherto CS/CBP-associated genes, such as PTX3, PGK1 and Resistin, was confirmed using real-time quantitative RT-PCR. In support of the mRNA data, differential expression of MMP9, MIP1alpha and MIP1beta plasma proteins was further confirmed in 34 additional patients. CONCLUSIONS: Analysis of blood transcriptome uncovered critical signaling pathways governing the CS/CPB-induced pathophysiology. The molecular signaling underlying ischemia reperfusion and inflammatory response is highly intertwined and includes pro-inflammatory as well as cardioprotective elements. The herein identified candidate genes and pathways may provide promising prognostic biomarker and therapeutic targets.

  1. Transcutaneous measurement of volume blood flow (United States)

    Daigle, R. E.; Mcleod, F. D.; Miller, C. W.; Histand, M. B.; Wells, M. K.


    Blood flow velocity measurements, using Doppler velocimeter, are described. The ability to measure blood velocity using ultrasound is derived from the Doppler effect; the change in frequency which occurs when sound is reflected or transmitted from a moving target. When ultrasound of the appropriate frequency is transmitted through a moving blood stream, the blood cells act as point scatterers of ultrasonic energy. If this scattered ultrasonic energy is detected, it is found to be shifted in frequency according to the velocity of the blood cells, nu, the frequency of the incident sound, f sub o, the speed of sound in the medium, c, and the angle between the sound beam and the velocity vector, o. The relation describing this effect is known as the Doppler equation. Delta f = 2 f sub o x nu x cos alpha/c. The theoretical and experimental methods are evaluated.

  2. Cerebral blood flow in acute mountain sickness

    DEFF Research Database (Denmark)

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


    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...

  3. Effects of aortic irregularities on blood flow. (United States)

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


    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.

  4. Ergot alkaloids decrease rumen epithelial blood flow (United States)

    Two experiments were conducted to determine if ergot alkaloids affect blood flow to the absorptive surface of the rumen of steers. Steers (n=8 total) were pair-fed alfalfa cubes at 1.5× NEM and received ground endophyte-infected tall fescue seed (E+) or endophyte-free tall fescue seed (E-) via rumen...

  5. Frequency encoding in renal blood flow regulation

    DEFF Research Database (Denmark)

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


    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...

  6. Blood flow dynamics in the snake spectacle. (United States)

    van Doorn, Kevin; Sivak, Jacob G


    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.

  7. Coronary flow velocity analysis during short term follow up after coronary reperfusion: use of transthoracic Doppler echocardiography to predict regional wall motion recovery in patients with acute myocardial infarction


    Hozumi, T; Kanzaki, Y; Ueda, Y.; Yamamuro, A; Takagi, T; Akasaka, T; Homma, S; Yoshida, K.; Yoshikawa, J


    Background: A recent study using a Doppler guide wire showed that coronary flow velocity measurements immediately after coronary reperfusion were useful in predicting recovery of regional left ventricular function. The value of coronary flow velocity analyses during follow up after reperfusion has not been established in the clinical setting.

  8. Physiologically tolerable insulin reduces myocardial injury and improves cardiac functional recovery in myocardial ischemic/reperfused dogs. (United States)

    Zhang, Hang-Xiang; Zang, Yi-Min; Huo, Jian-Hua; Liang, Shao-Jun; Zhang, Hai-Feng; Wang, Yue-Min; Fan, Qian; Guo, Wen-Yi; Wang, Hai-Chang; Gao, Feng


    This study was designed to examine whether physiologically tolerable insulin, which maintains lower blood glucose, can protect the myocardium against ischemia/reperfusion (I/R) injury in a preclinical large animal model. Adult dogs were subjected to 50 minutes of myocardial ischemia (80% reduction in coronary blood flow) followed by 4 hours of reperfusion and treated with vehicle, glucose-insulin-potassium (GIK; glucose, 250 g/L; insulin, 60 U/L; potassium, 80 mmol/L), GK, or low-dose insulin (30 U/L) 10 minutes before reperfusion. Treatment with GIK exerted significant cardioprotective effects as evidenced by improved cardiac function, improved coronary blood flow, reduced infarct size, and myocardial apoptosis. In contrast, treatment with GK increased blood glucose level and aggravated myocardial I/R injury. It is interesting that treatment with insulin alone at the dose that reduced blood glucose to a clinically tolerable level exerted significant cardioprotective effects that were comparable to that seen in the GIK-treated group. This low-dose insulin had no effect on coronary blood flow after reperfusion but markedly reduced coronary reactive hyperemia and switched myocardial substrate uptake from fat to carbohydrate. Our results suggest that lower glucose supply to the ischemic myocardium at early reperfusion may create a "metabolic postconditioning" and thus reduce myocardial ischemia/reperfusion injury after prolonged reperfusion.

  9. Ocular Blood Flow and Normal Tension Glaucoma

    Directory of Open Access Journals (Sweden)

    Ning Fan


    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.

  10. Dexmedetomidine decreases the oral mucosal blood flow. (United States)

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


    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.

  11. Effects of rapamycin on cerebral oxygen supply and consumption during reperfusion after cerebral ischemia. (United States)

    Chi, O Z; Barsoum, S; Vega-Cotto, N M; Jacinto, E; Liu, X; Mellender, S J; Weiss, H R


    Activation of the mammalian target of rapamycin (mTOR) leads to cell growth and survival. We tested the hypothesis that inhibition of mTOR would increase infarct size and decrease microregional O2 supply/consumption balance after cerebral ischemia-reperfusion. This was tested in isoflurane-anesthetized rats with middle cerebral artery blockade for 1h and reperfusion for 2h with and without rapamycin (20mg/kg once daily for two days prior to ischemia). Regional cerebral blood flow was determined using a C(14)-iodoantipyrine autoradiographic technique. Regional small-vessel arterial and venous oxygen saturations were determined microspectrophotometrically. The control ischemic-reperfused cortex had a similar blood flow and O2 consumption to the contralateral cortex. However, microregional O2 supply/consumption balance was significantly reduced in the ischemic-reperfused cortex. Rapamycin significantly increased cerebral O2 consumption and further reduced O2 supply/consumption balance in the reperfused area. This was associated with an increased cortical infarct size (13.5±0.8% control vs. 21.5±0.9% rapamycin). We also found that ischemia-reperfusion increased AKT and S6K1 phosphorylation, while rapamycin decreased this phosphorylation in both the control and ischemic-reperfused cortex. This suggests that mTOR is important for not only cell survival, but also for the control of oxygen balance after cerebral ischemia-reperfusion.

  12. Protective Effect of Angiopoietin-1 on the Blood Brain Barrier after Focal Cerebral IschemiaReperfusion Injury in Rats

    Directory of Open Access Journals (Sweden)

    Xuan GAO


    Full Text Available Objective: To observe the protective effect of angiopoietin-1 (Ang-1 on the blood brain barrier (BBB after focal cerebral ischemia-reperfusion injury (CIRI in rats. Methods: Forty male healthy Wister rats were selected. The focal CIRI models were established using middle cerebral artery occlusion and 30 rats were divided into sham-operation group (n=10, normal saline group (NS group (n=10 and Ang-1 treatment group (n=10. The rats were killed 48 h after reperfusion, and brain water content, BBB permeability, cerebral infarction volume and neurological severity scores in rats were detected respectively. Results: 48 h after reperfusion, both the brain water content and Evans blue (EB content in Ang-1 treatment group were significantly lower than in NS control [(68.69±4.46 % vs. (79.08±4.12 %, P<0.001; (98.60±10.56 μg/g vs. (379.90±21.64 μg/g, P<0.001], and there was no statistical significance by comparison to those in sham-operation group [(65.37±3.28 %; (89.62±8.65 μg/g, P>0.05]. The cerebral infarction volume in Ang-1 treatment group was markedly smaller than in NS group [(0.119±0.022 cm3 vs. (0.407±0.036 cm3, P<0.001], and no significant difference was presented when compared with sham-operation group [(0.104±0.011 cm3, P>0.05]. Besides, the neurological severity scores in Ang-1 treatment group were notably lower than in NS group [(1.83±0.29 points vs. (2.87±0.34 points, P<0.001], but higher than in sham-operation group [(0.79±0.11 points, P<0.001]. Conclusion: Ang-1 can decrease BBB permeability after focal CIRI in rats, so it has a protective effect on CIRI.

  13. Addition of tanshinone ⅡA to UW solution decreases skeletal muscle ischemia-reperfusion injury

    Institute of Scientific and Technical Information of China (English)

    Hong-gang WANG; Zhi-yong LI; Xiao-lin LIU


    Aim: To investigate whether tanshinone ⅡA could improve the effect of UW solution for skeletal muscle preservation and to determine the dose range of tanshinone ⅡA providing optimal protection during ischemia and reperfusion. Methods: Ischemic rat limbs were perfused with UW solution or UW plus tanshinone ⅡA (UW+T, 0.05, 0.1, or 0.2 mg/mL) for 0.5 h before reperfusion; controls (I/R) received no perfusion. Serum creatine phosphokinase (CPK), aspartate aminotransferase (AST), and lactate dehydrogenase (LDH) were measured pre-ischemia and after reperfusion (2-h, 4-h, and 6-h). Muscle water content, superoxide dismutase (SOD), malondialdehyde (MDA), adenosine triphosphatase (ATPase) were assessed pre-reperfusion and after 6-h reperfusion. Intercellular adhesion molecule-1 (ICAM-1) and apoptosis were detected after 6-h reperfusion. Reperfusion blood flow was monitored during reperfusion period. Results: UW and UW+T prevented luxury perfusion during reperfusion and inhibited ICAM-1 expression and apoptosis after 6-h reperfusion. Serum CPK, AST, and LDH levels in UW rats were significantly less than those in controls after 2-h reperfusion (no difference, 4-h or 6-h reperfusion). After 4-h ischemia, there were significant differences in water content, MDA, SOD, and ATPase between UW and controls, but no difference after 6-h reperfusion. All tests with UW+T rats were significantly different from control results at corresponding durations. Higher tanshinone doses improved results. Conclusion: UW plus tanshinone ⅡA increased protection against I/R injury, suggesting that tanshinone ⅡA has clinical value.

  14. [Effect of different concentrations liposomal emoxipine on coronary flow, contractive and pump function of the isolated rat heart after normotermic ischema and further reperfusion]. (United States)

    Toropova, Ia G; Mukhamadiiarov, R A; Golovkin, A S


    In the experiments on the isolated perfused rat heart we studied the effects of liposomes containing different concentrations (0.25 and 0.1 mg/ml) of emoxipine on coronary flow, contractive and pump function of the isolated heart, which was effected by total normothermical ischemia and reperfusion. The parameters of the contractile activity of hearts, coronary flow and pump function of the hearts were assessed. It was detected that the introduction of the liposomal emoxipine during ischemia provides a protective effect against ischemic and reperfusion myocardial damage and smaller concentration of the emoxipin (0.1 mg/ml) in composition with the liposomes promote the best recovery of contractile activity and the pumping function of the ischemic heart in the period of the reperfusion.

  15. Red blood cell clusters in Poiseuille flow (United States)

    Ghigliotti, Giovanni; Selmi, Hassib; Misbah, Chaouqi; Elasmi, Lassaad


    We present 2D numerical simulations of sets of vesicles (closed bags of a lipid bilayer membrane) in a parabolic flow, a setup that mimics red blood cells (RBCs) in the microvasculature. Vesicles, submitted to sole hydrodynamical interactions, are found to form aggregates (clusters) of finite size. The existence of a maximal cluster size is pointed out and characterized as a function of the flow intensity and the swelling ratio of the vesicles. Moreover bigger clusters move at lower velocity, a fact that may prove of physiological interest. These results quantify previous observations of the inhomogeneous distribution of RBCs in vivo (Gaehtgens et al., Blood Cells 6 - 1980). An interpretation of the phenomenon is put forward based on the presence of boli (vortices) between vesicles. Both the results and the explanation can be transposed to the three-dimensional case.

  16. Deterministic Aperiodic Sickle Cell Blood Flows (United States)

    Atsaves, Louis; Harris, Wesley


    In this paper sickle cell blood flow in the capillaries is modeled as a hydrodynamical system. The hydrodynamical system consists of the axisymmetric unsteady, incompressible Navier-Stokes equations and a set of constitutive equations for oxygen transport. Blood cell deformation is not considered in this paper. The hydrodynamical system is reduced to a system of non-linear partial differential equations that are then transformed into a system of three autonomous non-linear ordinary differential equations and a set of algebraic equations. We examine the hydrodynamical system to discern stable/unstable, periodic/nonperiodic, reversible/irreversible properties of the system. The properties of the solutions are driven in large part by the coefficients of the governing system of equations. These coefficients depend on the physiological properties of the sickle cell blood. The chaotic nature of the onset of crisis in sickle cell patients is identified. Research Assistant.

  17. Computational Analysis of Human Blood Flow (United States)

    Panta, Yogendra; Marie, Hazel; Harvey, Mark


    Fluid flow modeling with commercially available computational fluid dynamics (CFD) software is widely used to visualize and predict physical phenomena related to various biological systems. In this presentation, a typical human aorta model was analyzed assuming the blood flow as laminar with complaint cardiac muscle wall boundaries. FLUENT, a commercially available finite volume software, coupled with Solidworks, a modeling software, was employed for the preprocessing, simulation and postprocessing of all the models.The analysis mainly consists of a fluid-dynamics analysis including a calculation of the velocity field and pressure distribution in the blood and a mechanical analysis of the deformation of the tissue and artery in terms of wall shear stress. A number of other models e.g. T branches, angle shaped were previously analyzed and compared their results for consistency for similar boundary conditions. The velocities, pressures and wall shear stress distributions achieved in all models were as expected given the similar boundary conditions. The three dimensional time dependent analysis of blood flow accounting the effect of body forces with a complaint boundary was also performed.

  18. Atorvastatin preconditioning improves the forward blood flow in the no-reflow rats. (United States)

    Shao, Liang; Zhang, Yong; Ma, Aiqun; Zhang, Ping; Wu, Dayin; Li, Wenzhu; Wang, Jue; Liu, Kun; Wang, Zhaohui


    Atorvastatin is not only an antilipemic but also used as an anti-inflammatory medicine in heart disease. Our working hypothesis was that atorvastatin preconditioning could improve the forward blood flow in the no-reflow rats associated with inflammation. We investigated that two doses of atorvastatin preconditioning (20 and 5 mg/kg/day) could alleviate deterioration of early cardiac diastolic function in rats with inflammation detected by echocardiography and haemodynamics. This benefit was obtained from the effect of atorvastatin preconditioning on improving forward blood flow and preserving the infarct cardiomyocytes, which was estimated by Thioflavin S and TTC staining in rats with myocardial ischemia/reperfusion. Subsequently, the improving of forward blood flow was ascribed to reduction of microthrombus in microvascular and myocardial fibrosis observed by MSB and Masson's trichrome staining with atorvastatin preconditioning. Ultimately, we found that atorvastatin preconditioning could reduce inflammation factor, such as tumor necrosis factor-α and fibrinogen-like protein 2, both in myocardial and in mononuclear cells, which probably attribute to microcirculation dysfunction in no-reflow rats detected by immunohistochemistry staining, western blot, and ELISA detection, respectively. In conclusion, atorvastatin preconditioning could alleviate deterioration of early cardiac diastolic function and improve the forward blood flow in the no-reflow rats attributing to reduction of TNF-α and fgl-2 expression.

  19. Blood flow measurements and clot detection with nearinfrared spectroscopy


    Rossow, MJ; Gatto, R.; D'amico, E.; Mantulin, WW; Gratton, E


    Detecting impeded blood flow and locating the clot causing it is a major challenge in neurosurgery. We propose an instrument that uses near-infrared spectroscopy to simultaneously detect clots and measure blood flow. © 2006 Optical Society of America.

  20. Relationship of gelatinases-tight junction proteins and blood-brain barrier permeability in the early stage of cerebral ischemia and reperfusion

    Institute of Scientific and Technical Information of China (English)

    Haolin Xin; Wenzhao Liang; Jing Mang; Lina Lin; Na Guo; Feng Zhang; Zhongxin Xu


    Gelatinases matrix metalloproteinase-2 and matrix metalloproteinase-9 have been shown to mediate claudin-5 and occludin degradation, and play an important regulatory role in blood-brain barrier permeability. This study established a rat model of 1.5-hour middle cerebral artery occlusion with reperfusion. Protein expression levels of claudin-5 and occludin gradually decreased in the early stage of reperfusion, which corresponded to the increase of the gelatinolytic activity of matrix metalloproteinase-2 and matrix metalloproteinase-9. In addition, rats that received treatment with matrix metalloproteinase inhibitor N-[(2R)-2-(hydroxamidocarbonylmethyl)-4-methylpenthanoyl]-L- tryptophan methylamide (GM6001) showed a significant reduction in Evans blue leakage and an inhibition of claudin-5 and occludin protein degradation in striatal tissue. These data indicate that matrix metalloproteinase-2 and matrix metalloproteinase-9-mediated claudin-5 and occludin degradation is an important reason for blood-brain barrier leakage in the early stage of reperfusion. The leakage of the blood-brain barrier was present due to gelatinases-mediated degradation of claudin-5 and occludin proteins. We hypothesized that the timely closure of the structural component of the blood-brain barrier (tight junction proteins) is of importance.

  1. Effect of black tea consumption on brachial artery flow-mediated dilation and ischaemia-reperfusion in humans. (United States)

    Schreuder, Tim H A; Eijsvogels, Thijs M H; Greyling, Arno; Draijer, Richard; Hopman, Maria T E; Thijssen, Dick H J


    Tea consumption is associated with reduced cardiovascular risk. Previous studies found that tea flavonoids work through direct effects on the vasculature, leading to dose-dependent improvements in endothelial function. Cardioprotective effects of regular tea consumption may relate to the prevention of endothelial ischaemia-reperfusion (IR) injury. Therefore, we examined the effect of black tea consumption on endothelial function and the ability of tea to prevent IR injury. In a randomized, crossover study, 20 healthy subjects underwent 7 days of tea consumption (3 cups per day) or abstinence from tea. We examined brachial artery (BA) endothelial function via flow-mediated dilation (FMD), using high resolution echo-Doppler, before and 90 min after tea or hot water consumption. Subsequently, we followed a 20-min ischaemia and 20-min reperfusion protocol of the BA after which we measured FMD to examine the potential of tea consumption to protect against IR injury. Tea consumption resulted in an immediate increase in FMD% (pre-consumption: 5.8 ± 2.5; post-consumption: 7.2 ± 3.2; p tea consumption (p tea ingestion improves BA FMD. However, the impact of the IR protocol on FMD was not influenced by tea consumption. Therefore, the cardioprotective association of tea ingestion relates to a direct effect of tea on the endothelium in humans in vivo.

  2. Glial and neuronal control of brain blood flow

    DEFF Research Database (Denmark)

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


    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...... in our understanding of cerebral blood flow control have important implications for the development of new therapeutic approaches....

  3. Decorrelation-based blood flow velocity estimation: effect of spread of flow velocity, linear flow velocity gradients, and parabolic flow.

    NARCIS (Netherlands)

    Lupotti, F.A.; Steen, A.F.W. van der; Mastik, F.; Korte, C.L. de


    In recent years, a new method to measure transverse blood flow, based on the decorrelation of the radio frequency (RF) signals has been developed. In this paper, we investigated the influence of nonuniform flow on the velocity estimation. The decorrelation characteristics of transverse blood flow us

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

    Energy Technology Data Exchange (ETDEWEB)

    Hock, J.M.; Kim, S.


    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. Skin blood flow changes during apneic spells in preterm infants

    NARCIS (Netherlands)

    Suichies, H.E.; Aarnoudse, J.G.; Okken, A.; Jentink, H.W.; Mul, de F.F.M.; Greve, J.


    Changes in skin blood flow during apneic spells were determined in 18 preterm infants using a diode laser Doppler flow meter without light conducting fibres. Heart rate, nasal air flow, impedance pneumography, skin and incubator temperature and laser Doppler skin blood flow were recorded simultaneou

  6. Absolute quantification of myocardial blood flow. (United States)

    Yoshinaga, Keiichiro; Manabe, Osamu; Tamaki, Nagara


    With the increasing availability of positron emission tomography (PET) myocardial perfusion imaging, the absolute quantification of myocardial blood flow (MBF) has become popular in clinical settings. Quantitative MBF provides an important additional diagnostic or prognostic information over conventional visual assessment. The success of MBF quantification using PET/computed tomography (CT) has increased the demand for this quantitative diagnostic approach to be more accessible. In this regard, MBF quantification approaches have been developed using several other diagnostic imaging modalities including single-photon emission computed tomography, CT, and cardiac magnetic resonance. This review will address the clinical aspects of PET MBF quantification and the new approaches to MBF quantification.

  7. Nonlinear interactions in renal blood flow regulation

    DEFF Research Database (Denmark)

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


    , identical except for the strength of TGF input, with a third, fixed resistance segment representing prearteriolar vessels. The two arteriolar segments are electrically coupled. The arteriolar, glomerular, and tubular models are linked; TGF modulates arteriolar circumference, which determines vascular...... resistance and glomerular capillary pressure. The model couples TGF input to voltage-gated Ca channels. It predicts autoregulation of GFR and renal blood flow, matches experimental measures of tubular pressure and macula densa NaCl concentration, and predicts TGF-induced oscillations and a faster smaller...

  8. Phosphomimetic modulation of eNOS improves myocardial reperfusion and mimics cardiac postconditioning in mice.

    Directory of Open Access Journals (Sweden)

    Terrence Pong

    Full Text Available OBJECTIVE: Myocardial infarction resulting from ischemia-reperfusion injury can be reduced by cardiac postconditioning, in which blood flow is restored intermittently prior to full reperfusion. Although key molecular mechanisms and prosurvival pathways involved in postconditioning have been identified, a direct role for eNOS-derived NO in improving regional myocardial perfusion has not been shown. The objective of this study is to measure, with high temporal and spatial resolution, regional myocardial perfusion during ischemia-reperfusion and postconditioning, in order to determine the contribution of regional blood flow effects of NO to infarct size and protection. METHODS AND RESULTS: We used myocardial contrast echocardiography to measure regional myocardial blood flow in mice over time. Reperfusion after myocardial ischemia-reperfusion injury is improved by postconditioning, as well as by phosphomimetic eNOS modulation. Knock-in mice expressing a phosphomimetic S1176D form of eNOS showed improved myocardial reperfusion and significantly reduced infarct size. eNOS knock-out mice failed to show cardioprotection from postconditioning. The size of the no-reflow zone following ischemia-reperfusion is substantially reduced by postconditioning and by the phosphomimetic eNOS mutation. CONCLUSIONS AND SIGNIFICANCE: Using myocardial contrast echocardiography, we show that temporal dynamics of regional myocardial perfusion restoration contribute to reduced infarct size after postconditioning. eNOS has direct effects on myocardial blood flow following ischemia-reperfusion, with reduction in the size of the no-reflow zone. These results have important implications for ongoing clinical trials on cardioprotection, because the degree of protective benefit may be significantly influenced by the regional hemodynamic effects of eNOS-derived NO.

  9. Dexmedetomidine Attenuates Blood-Spinal Cord Barrier Disruption Induced by Spinal Cord Ischemia Reperfusion Injury in Rats

    Directory of Open Access Journals (Sweden)

    Bo Fang


    Full Text Available Background/Aims: Dexmedetomidine has beneficial effects on ischemia reperfusion (I/R injury to the spinal cord, but the underlying mechanisms are not fully understood. This study investigated the effects and possible mechanisms of dexmedetomidine on blood-spinal cord barrier (BSCB disruption induced by spinal cord I/R injury. Methods: Rats were intrathecally pretreated with dexmedetomidine or PBS control 30 minutes before undergoing 14-minute occlusion of aortic arch. Hind-limb motor function was assessed using Tarlov criteria, and motor neurons in the ventral gray matter were counted by histological examination. The permeability of the BSCB was examined using Evans blue (EB as a vascular tracer. The spinal cord edema was evaluated using the wet-dry method. The expression and localization of matrix metalloproteinase-9 (MMP-9, Angiopoietin-1 (Ang1 and Tie2 were assessed by western blot, real-time polymerase chain reaction, and immunofluorescence. Results: Intrathecal preconditioning with dexmedetomidine minimized the neuromotor dysfunction and histopathological deficits, and attenuated EB extravasation after spinal cord I/R injury. In addition, dexmedetomidine preconditioning suppressed I/R-induced increase in MMP-9. Finally, Dexmedetomidine preconditioning enhanced the Ang1-Tie2 system activity after spinal cord I/R injury. Conclusions: Dexmedetomidine preconditioning stabilized the BSCB integrity against spinal cord I/R injury by inhibition of MMP-9, and enhancing the Ang1-Tie2 system.

  10. Tissue blood flow mapping using laser technology (United States)

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


    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.

  11. Cerebral blood flow tomography with xenon-133

    Energy Technology Data Exchange (ETDEWEB)

    Lassen, N.A.


    Cerebral blood flow (CBF) can be measured tomographically by inhalation of Xenon-/sup 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 computed tomograph (SPECT) is required. Two brain-dedicated SPECT systems designed for this purpose are mentioned, and the method is described with special reference to the limitations inherent in the soft energy of the 133Xe primary photons. CBF tomography can be used for a multitude of clinical and investigative purposes. This article discusses in particular its use for the selection of patients with carotid occlusion for extracranial/intracranial bypass surgery, for detection of severe arterial spasm after aneurysm bleeding, and for detection of low flow areas during severe migraine attacks. The use of other tracers for CBF tomography using SPECT is summarized with emphasis on the /sup 99m/Tc chelates that freely pass the intact blood-brain barrier. The highly sensitive brain-dedicated SPECT systems described are a prerequisite for achieving high resolution tomograms with such tracers.

  12. Regional cerebral blood flow in schizophrenics

    Energy Technology Data Exchange (ETDEWEB)

    Uchino, J.; Ohta, Y.; Nakane, Y.; Mori, H.; Hirota, N.; Yonekura, M.


    The present study on schizophrenics dealt with the relationship of regional cerebral blood flow (rCBF) to age, disease duration, and treatment length with chlorpromazine hydrochloride (CPZ). Regional cerebral blood flow in 28 cerebral regions of interest was measured by iv injection of /sup 133/X in 54 schizophrenic patients and 39 healthy volunteers. Neither age nor dosage of CPZ significantly influenced rCBF. All patients, including 11 treated for a short period of time (6 months or less), were characterized by having a decreased rCBF over the whole cerebrum. Thirty-four patients treated for a long period of time (2 years or more) had a varied rCBF distribution in the left hemisphere, with the most predominant feature being the decrease in rCBF in the frontal lobe (i.e., hypofrontality); however, there was no linear correlation between rCBF and disease duration. A decreased rCBE in the right occipital region was seen in patients with paranoid schizophrenia, suggesting that manifestations of symptoms may depend on disturbed regions. These results suggest that cerebral dysfunction in schizophrenic patients may not be restricted to the frontal lobe, but cover the whole cerebrum, and that nonuniform dysfunction in various regions of the cerebrum, including the frontal lobe, may be involved in manifestations of symptoms.

  13. Ischemia and reperfusion injury of the rat liver: the role of nimodipine. (United States)

    Chávez-Cartaya, R E; Pino DeSola, G; Ramirez-Romero, P; Calne, R Y; Jamieson, N V


    The protective effect of the calcium channel blocker nimodipine on liver ischemia and reperfusion was studied in the rat. The homeostasis of intracellular calcium ions seems to be a determinant factor in the cell injury that appears after ischemia and reperfusion. Nimodipine was used to downregulate the calcium levels in the cytosol of the ischemic cell, the hypothetical role of Ca2+ in the pathogenesis of ischemia and reperfusion injury. The experimental procedure consisted of the temporary interruption of blood flow to the left lateral and medial lobes of the rat liver and subsequent reperfusion after a period of 45 min of ischemia. Nimodipine (10 micrograms/kg body wt) was administered either before or after the onset of ischemia. The postischemic liver blood flow and liver oxyhemoglobin saturation were recorded using a He-Ne laser Doppler flowmeter and photometer, which showed, in the pretreated group, a recovery of reperfusion blood flow (58.1%) and liver reflectance (85.5%) significantly better (P flow (32.8%) and reflectance (70.5%). In the group that received nimodipine after ischemia, the recovery of the blood flow and the postreperfusion liver reflectance were not significantly better than those in the untreated control group. ALT levels (P < 0.05), galactose elimination capacity (P < 0.001), and histological studies also showed a protective effect of calcium antagonist nimodipine when administered before ischemia.

  14. Gastric mucosal electrical potential difference, pH, blood flow, and morphology during hypoxia and selective gastric ischaemia with and without allopurinol pretreatment in anaesthetized dogs

    DEFF Research Database (Denmark)

    Højgaard, L; Bülow, J B; Madsen, J


    Ischaemia has been implicated in the pathogenesis of gastric mucosal disorders. The aim of this investigation was to study the gastric mucosal electrical potential difference (PD), pH, blood flow and morphology during hypoxia, gastric ischaemia, and gastric ischaemia following inhibition of free...... radical formation with allopurinol. PD and pH were measured simultaneously with an intragastric microelectrode, and the PD values were corrected for the liquid junction potentials created by the intragastric pH variation. Blood flow was measured by the radiolabelled microsphere technique in 18...... anaesthetized dogs. Short general hypoxia and short ischaemia caused reversible declines in PD, increases in pH, and no morphological damage. Ischaemia for 1 h caused a significant decline in PD persistent after reperfusion, an increase in pH, and morphological PD, but after reperfusion PD was normalized. Gross...

  15. Effects of salidroside pretreatment on expression of tumor necrosis factor-alpha and permeability of blood brain barrier in rat model of focal cerebralischemia-reperfusion injury. (United States)

    Han, Tian


    To observe changes in expression of tumor necrosis factor (TNF)-alpha and permeability of blood brain barrier after salidroside pretreatment in rats with injury induced by focal cerebralischemia-reperfusion. Forty-five male SD rats were randomly divided into three groups (n=15): control group, ischemia-reperfusion (IR) model group, and salidroside pretreatment group. Before the IR model establishment, the rats in the salidroside pretreatment group were intraperitoneally administered with salidroside at a dose of 24 mg/(kg·d) for 7 d. After 30 min post the last administration, the IR model was induced by occlusion of middle cerebral artery with a filament. After 24 h post the operation, the water content and Evens blue content in the ischemia cerebral hemisphere were determined, and the level of TNF-alpha mRNA was detected by the semi-quantitative RT-PCR. Compared with the IR model group, the salidroside pretreatment group had significantly lower (Psalidroside pretreatment alleviated the focal cerebralischemia-reperfusion injury in the rat model, possibly by decreasing the permeability of blood brain barrier, attenuating brain edema and reducing TNF-alpha expression. Copyright © 2013 Hainan Medical College. Published by Elsevier B.V. All rights reserved.

  16. Effects of salidroside pretreatment on expression of tumor necrosis factor-alpha and permeability of blood brain barrier in rat model of focal cerebralischemia-reperfusion injury

    Institute of Scientific and Technical Information of China (English)

    Tian Han


    Objective:To observe changes in expression of tumor necrosis factor(TNF)-alpha and permeability of blood brain barrier after salidroside pretreatment in rats with injury induced by focal cerebralischemia-reperfusion.Methods:Forty-five maleSD rats were randomly divided into three groups(n=15): control group, ischemia-reperfusion(IR) model group, and salidroside pretreatment group.Before theIR model establishment, the rats in the salidroside pretreatment group were intraperitoneally administered with salidroside at a dose of24 mg/(kg•d) for7 d.After30 min post the last administration, theIR model was induced by occlusion of middle cerebral artery with a filament.After24 h post the operation, the water content andEvens blue content in the ischemia cerebral hemisphere were determined, and the level of TNF-alpha mRNA was detected by the semi-quantitativeRT-PCR.Results:Compared with theIR model group, the salidroside pretreatment group had significantly lower(P<0.05) water content andEvens blue content in the ischemia cerebral hemisphere and also had significantly lower(P<0.05) level of TNF-alpha in the ischemic cerebral cortex tissue.Conclusions:The salidroside pretreatment alleviated the focal cerebralischemia-reperfusion injury in the rat model, possibly by decreasing the permeability of blood brain barrier, attenuating brain edema and reducingTNF-alpha expression.

  17. Reperfusion injury following cerebral ischemia: pathophysiology, MR imaging, and potential therapies

    Energy Technology Data Exchange (ETDEWEB)

    Pan, Jie; Konstas, Angelos-Aristeidis; Bateman, Brian; Pile-Spellman, John [Columbia University, Department of Radiology, New York, NY (United States); Ortolano, Girolamo A. [Pall Corporation, East Hills, NY (United States)


    Restoration of blood flow following ischemic stroke can be achieved by means of thrombolysis or mechanical recanalization. However, for some patients, reperfusion may exacerbate the injury initially caused by ischemia, producing a so-called ''cerebral reperfusion injury''. Multiple pathological processes are involved in this injury, including leukocyte infiltration, platelet and complement activation, postischemic hyperperfusion, and breakdown of the blood-brain barrier. Magnetic resonance imaging (MRI) can provide extensive information on this process of injury, and may have a role in the future in stratifying patients' risk for reperfusion injury following recanalization. Moreover, different MRI modalities can be used to investigate the various mechanisms of reperfusion injury. Antileukocyte antibodies, brain cooling and conditioned blood reperfusion are potential therapeutic strategies for lessening or eliminating reperfusion injury, and interventionalists may play a role in the future in using some of these therapies in combination with thrombolysis or embolectomy. The present review summarizes the mechanisms of reperfusion injury and focuses on the way each of those mechanisms can be evaluated by different MRI modalities. The potential therapeutic strategies are also discussed. (orig.)

  18. Noninvasive optical measurement of cerebral blood flow in mice using molecular dynamics analysis of indocyanine green.

    Directory of Open Access Journals (Sweden)

    Taeyun Ku

    Full Text Available In preclinical studies of ischemic brain disorders, it is crucial to measure cerebral blood flow (CBF; however, this requires radiological techniques with heavy instrumentation or invasive procedures. Here, we propose a noninvasive and easy-to-use optical imaging technique for measuring CBF in experimental small animals. Mice were injected with indocyanine green (ICG via tail-vein catheterization. Time-series near-infrared fluorescence signals excited by 760 nm light-emitting diodes were imaged overhead by a charge-coupled device coupled with an 830 nm bandpass-filter. We calculated four CBF parameters including arrival time, rising time and mean transit time of a bolus and blood flow index based on time and intensity information of ICG fluorescence dynamics. CBF maps were generated using the parameters to estimate the status of CBF, and they dominantly represented intracerebral blood flows in mice even in the presence of an intact skull and scalp. We demonstrated that this noninvasive optical imaging technique successfully detected reduced local CBF during middle cerebral artery occlusion. We further showed that the proposed method is sufficiently sensitive to detect the differences between CBF status in mice anesthetized with either isoflurane or ketamine-xylazine, and monitor the dynamic changes in CBF after reperfusion during transient middle cerebral artery occlusion. The near-infrared optical imaging of ICG fluorescence combined with a time-series analysis of the molecular dynamics can be a useful noninvasive tool for preclinical studies of brain ischemia.

  19. Cerebral blood flow and metabolism during sleep

    DEFF Research Database (Denmark)

    Madsen, Peter Lund; Vorstrup, S


    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...

  20. Intraoperative cerebral blood flow imaging of rodents (United States)

    Li, Hangdao; Li, Yao; Yuan, Lu; Wu, Caihong; Lu, Hongyang; Tong, Shanbao


    Intraoperative monitoring of cerebral blood flow (CBF) is of interest to neuroscience researchers, which offers the assessment of hemodynamic responses throughout the process of neurosurgery and provides an early biomarker for surgical guidance. However, intraoperative CBF imaging has been challenging due to animal's motion and position change during the surgery. In this paper, we presented a design of an operation bench integrated with laser speckle contrast imager which enables monitoring of the CBF intraoperatively. With a specially designed stereotaxic frame and imager, we were able to monitor the CBF changes in both hemispheres during the rodent surgery. The rotatable design of the operation plate and implementation of online image registration allow the technician to move the animal without disturbing the CBF imaging during surgery. The performance of the system was tested by middle cerebral artery occlusion model of rats.

  1. Dynamic mechanisms of cardiac oxygenation during brief ischemia and reperfusion

    Energy Technology Data Exchange (ETDEWEB)

    Parsons, W.J.; Rembert, J.C.; Bauman, R.P.; Greenfield, J.C. Jr.; Piantadosi, C.A. (Duke Univ., Durham (USA))


    Myocardial oxygenation may be altered markedly by changes in tissue blood flow. During brief ischemia and reperfusion produced by transient occlusion of the left anterior descending artery in 10 open-chest dogs, changes in the oxygenation of tissue hemoglobin (Hb) plus myoglobin (Mb) and the oxidation-reduction (redox) state of mitochondrial cytochrome aa3 were monitored continuously using near-infrared spectroscopy. The nondestructive optical technique indicated that coronary occlusion produced an abrupt drop in tissue oxygen stores (tHb02 + Mb02), tissue blood volume (tBV), and the oxidation level of cytochrome aa3. Changes in the cytochrome oxidation state were related inversely to transmural collateral blood flow within the ischemic region (r = 0.77) measured with radiolabeled microspheres. Furthermore, there was a direct relationship (r = 0.91) between collateral blood flow and the tissue level of desaturated Hb and Mb (tHb + Mb). Reperfusion after 2 min of ischemia led to a synchronous overshoot of baseline in coronary flow and tBV followed by supranormal increases in tHb + Mb02 and the oxidation level of cytochrome aa3. The tHb + Mb level increased transiently during reperfusion. This response correlated inversely with collateral flow during ischemia (r = 0.91). Accordingly, the time required to reach peak tHb + Mb levels was shortest in dogs with high collateral flows (r = 0.75). Thus collateral blood flow partially sustains myocardial oxygenation during coronary artery occlusion and influences tissue reoxygenation early during reperfusion.

  2. Mapping blood flow directionality in the human brain. (United States)

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


    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.

  3. Cerebral blood flow simulations in realistic geometries

    Directory of Open Access Journals (Sweden)

    Szopos Marcela


    Full Text Available The aim of this work is to perform the computation of the blood flow in all the cerebral network, obtained from medical images as angiographies. We use free finite elements codes as FreeFEM++. We first test the code on analytical solutions in simplified geometries. Then, we study the influence of boundary conditions on the flow and we finally perform first computations on realistic meshes. L’objectif est ici de simuler l’écoulement sanguin dans tout le réseau cérébral (artériel et veineux obtenu à partir d’angiographies cérébrales 3D à l’aide de logiciels d’éléments finis libres, comme FreeFEM++. Nous menons d’abord une étude détaillée des résultats sur des solutions analytiques et l’influence des conditions limites à imposer dans des géométries simplifiées avant de travailler sur les maillages réalistes.

  4. The effect of hyperosmotic solutions on the hepatic blood flow

    DEFF Research Database (Denmark)

    Winkler, K; Henriksen, Jens Henrik Sahl; Tygstrup, N


    The present study was undertaken in order to measure the effect of hyperosmotic solutions on portal and hepatic blood flow. In five anaesthetized pigs without arterial blood supply to the liver, portal blood flow rate was measured (electromagnetic flowmeter) during 5 min lasting intravenous infus...... for these osmotic effects are not known, but they have to be taken into consideration in studies of the portal and hepatic blood flow.......The present study was undertaken in order to measure the effect of hyperosmotic solutions on portal and hepatic blood flow. In five anaesthetized pigs without arterial blood supply to the liver, portal blood flow rate was measured (electromagnetic flowmeter) during 5 min lasting intravenous...

  5. Lycium barbarum polysaccharides reduce neuronal damage, blood-retinal barrier disruption and oxidative stress in retinal ischemia/reperfusion injury.

    Directory of Open Access Journals (Sweden)

    Suk-Yee Li

    Full Text Available Neuronal cell death, glial cell activation, retinal swelling and oxidative injury are complications in retinal ischemia/reperfusion (I/R injuries. Lycium barbarum polysaccharides (LBP, extracts from the wolfberries, are good for "eye health" according to Chinese medicine. The aim of our present study is to explore the use of LBP in retinal I/R injury. Retinal I/R injury was induced by surgical occlusion of the internal carotid artery. Prior to induction of ischemia, mice were treated orally with either vehicle (PBS or LBP (1 mg/kg once a day for 1 week. Paraffin-embedded retinal sections were prepared. Viable cells were counted; apoptosis was assessed using TUNEL assay. Expression levels of glial fibrillary acidic protein (GFAP, aquaporin-4 (AQP4, poly(ADP-ribose (PAR and nitrotyrosine (NT were investigated by immunohistochemistry. The integrity of blood-retinal barrier (BRB was examined by IgG extravasations. Apoptosis and decreased viable cell count were found in the ganglion cell layer (GCL and the inner nuclear layer (INL of the vehicle-treated I/R retina. Additionally, increased retinal thickness, GFAP activation, AQP4 up-regulation, IgG extravasations and PAR expression levels were observed in the vehicle-treated I/R retina. Many of these changes were diminished or abolished in the LBP-treated I/R retina. Pre-treatment with LBP for 1 week effectively protected the retina from neuronal death, apoptosis, glial cell activation, aquaporin water channel up-regulation, disruption of BRB and oxidative stress. The present study suggests that LBP may have a neuroprotective role to play in ocular diseases for which I/R is a feature.

  6. Failure of P-selectin blockade alone to protect the liver from ischemia-reperfusion injury in the isolated blood-perfused rat liver

    Institute of Scientific and Technical Information of China (English)

    Samuel Wyllie; Neal R Barshes; Feng-Qin Gao; Saul J Karpen; John A Goss


    AIM: To determine if blockade of P-selectin in the isolated blood-perfused cold ex vivo rat liver model protects the liver from ischemia-reperfusion injury. METHODS: The effect of P-selectin blockade was assessed by employing an isolated blood-perfused cold ex vivo rat liver with or without P-selectin antibody treatment before and after 6 h of cold storage in University of Wisconsin solution.RESULTS: In our isolated blood-perfused rat liver model, pre-treatment with P-selectin antibody failed to protect the liver from ischemia-reperfusion injury, as judged by the elevated aspartate aminotransferase activity. In addition, P-selectin antibody treatment did not significantly reduced hepatic polymorphonuclear leukocyte accumulation after 120 min of perfusion. Histological evaluation of liver sections obtained at 120 min of perfusion showed significant oncotic necrosis in liver sections of both ischemic control and P-selectin antibody-treated groups. However, total bile production after 120 min of perfusion was significantly greater in P-selectin antibody-treated livers, compared to control livers. No significant difference in P-selectin and ICAM-1 mRNAs and proteins, GSH, GSSG, and nuclear NF-κB was found between control and P-selectin antibody-treated livers.CONCLUSION: In conclusion, we have shown that blockade of P-selectin alone failed to reduced polymorphonuclear leukocyte accumulation in the liver and protect hepatocytes from ischemia-reperfusion injury in the isolated blood-perfused cold-ex vivo rat liver model.

  7. Autoregulation of coronary blood flow in the isolated beating pig heart. (United States)

    Schampaert, Stéphanie; van 't Veer, Marcel; Rutten, Marcel C M; van Tuijl, Sjoerd; de Hart, Jurgen; van de Vosse, Frans N; Pijls, Nico H J


    The isolated beating pig heart model is an accessible platform to investigate the coronary circulation in its truly morphological and physiological state, whereas its use is beneficial from a time, cost, and ethical perspective. However, whether the coronary autoregulation is still intact is not known. Here, we study the autoregulation of coronary blood flow in the working isolated pig heart in response to brief occlusions of the coronary artery, to step-wise changes in left ventricular loading conditions and contractile states, and to pharmacologic vasodilating stimuli. Six slaughterhouse pig hearts (473 ± 40 g) were isolated, prepared, and connected to an external circulatory system. Through coronary reperfusion and controlled cardiac loading, physiological cardiac performance was achieved. After release of a coronary occlusion, coronary blood flow rose rapidly to an equal (maximum) level as the flow during control beats, independent of the duration of occlusion. Moreover, a linear relation was found between coronary blood flow and coronary driving pressure for a wide variation of preload, afterload, and contractility. In addition, intracoronary administration of papaverine did not yield a transient increase in blood flow indicating the presence of maximum coronary hyperemia. Together, this indicates that the coronary circulation in the isolated beating pig heart is in a permanent state of maximum hyperemia. This makes the model excellently suitable for testing and validating cardiovascular devices (i.e., heart valves, stent grafts, and ventricular assist devices) under well-controlled circumstances, whereas it decreases the necessity of sacrificing large mammalians for performing classical animal experiments. © 2013, Copyright the Authors. Artificial Organs © 2013 Wiley Periodicals, Inc. and International Center for Artificial Organs and Transplantation.

  8. Incomplete brain infarction of reperfused cortex may be quantitated with iomazenil

    DEFF Research Database (Denmark)

    Nakagawara, J; Sperling, B; Lassen, N A


    with ischemic stroke to detect viable neurons in cortex that appeared structurally intact on conventional neuroimaging studies. METHODS: Fourteen patients were selected by (1) angiography within 24 hours of onset showing embolic occlusion of an intracranial artery, (2) cerebral blood flow showing ischemia...... of moderate severity in 12 cases and spontaneous reflow in 2 cases, and (3) thrombolysis with reperfusion within 24 hours in most cases. Thirty reperfused cortical areas that remained structurally intact, 7 infarcted cortical areas, and 6 contralateral cerebellar areas with reduced blood flow were selected...

  9. Dynamic Effect of Rolling Massage on Blood Flow (United States)

    Chen, Yan-Yan; Yi, Hou-Hui; Li, Hua-Bing; Fang, Hai-Ping


    The Chinese traditional medical massage has been used as a natural therapy to eliminate some diseases. Here, the effect of the rolling massage frequency to the blood flow in the blood vessels under the rolling massage manipulation is studied by the lattice Boltzmann simulation. The simulation results show that when the frequency is smaller than or comparable to the pulsatile frequency of the blood flow, the effect on the blood flux by the rolling massage is small. On the contrast, if the frequency is twice or more times of the pulsatile frequency of the blood flow, the blood flux is greatly enhanced and increases linearly with respect to the frequency. Similar behavior has also been observed on the shear stress on the blood vessel walls. The result is helpful for understanding that the rolling massage has the function of promoting the blood circulation and removing the blood stasis.

  10. Dynamic Effect of Rolling Massage on Blood Flow

    Institute of Scientific and Technical Information of China (English)

    CHEN Yan-Yan; YI Hou-Hui; LI Hua-Bing; FANG Hai-Ping


    The Chinese traditional medical massage has been used as a natural therapy to eliminate some diseases.Here, the effect of the rolling massage frequency to the blood flow in the blood vessels under the rolling massage manipulation is studied by the lattice Boltzmann simulation.The simulation results show that when the frequency is smaller than or comparable to the putsatile frequency of the blood flow, the effect on the blood flux by the rolling massage is small.On the contrast, if the frequency is twice or more times of the putsatile frequency of the blood flow, the blood flux is greatly enhanced and increases linearly with respect to the frequency.Similar behavior has also been observed on the shear stress on the blood vessel waits.The result is helpful for understanding that the rolling massage has the function of promoting the blood circulation and removing the blood stasis.

  11. A polymeric micelle magnetic resonance imaging (MRI) contrast agent reveals blood-brain barrier (BBB) permeability for macromolecules in cerebral ischemia-reperfusion injury. (United States)

    Shiraishi, Kouichi; Wang, Zuojun; Kokuryo, Daisuke; Aoki, Ichio; Yokoyama, Masayuki


    Blood-brain barrier (BBB) opening is a key phenomenon for understanding ischemia-reperfusion injuries that are directly linked to hemorrhagic transformation. The recombinant human tissue-type plasminogen activator (rtPA) increases the risk of symptomatic intracranial hemorrhages. Recent imaging technologies have advanced our understanding of pathological BBB disorders; however, an ongoing challenge in the pre-"rtPA treatment" stage is the task of developing a rigorous method for hemorrhage-risk assessments. Therefore, we examined a novel method for assessment of rtPA-extravasation through a hyper-permeable BBB. To examine the image diagnosis of rtPA-extravasation for a rat transient occlusion-reperfusion model, in this study we used a polymeric micelle MRI contrast-agent (Gd-micelles). Specifically, we used two MRI contrast agents at 1h after reperfusion. Gd-micelles provided very clear contrast images in 15.5±10.3% of the ischemic hemisphere at 30min after i.v. injection, whereas a classic gadolinium chelate MRI contrast agent provided no satisfactorily clear images. The obtained images indicate both the hyper-permeable BBB area for macromolecules and the distribution area of macromolecules in the ischemic hemisphere. Owing to their large molecular weight, Gd-micelles remained in the ischemic hemisphere through the hyper-permeable BBB. Our results indicate the feasibility of a novel clinical diagnosis for evaluating rtPA-related hemorrhage risks. Copyright © 2017 Elsevier B.V. All rights reserved.

  12. Poloxamer 188 protects neurons against ischemia/reperfusion injury through preserving integrity of cell membranes and blood brain barrier.

    Directory of Open Access Journals (Sweden)

    Jin-Hua Gu

    Full Text Available Poloxamer 188 (P188, a multiblock copolymer surfactant, has been shown to protect against ischemic tissue injury of cardiac muscle, testes and skeletal muscle, but the mechanisms have not been fully understood. In this study, we explored whether P188 had a protective effect against cerebral ischemia/reperfusion injury and its underlying mechanisms. The in vivo results showed that P188 significantly reduced the infarct volume, ameliorated the brain edema and neurological symptoms 24 h after ischemia/reperfusion. In the long-term outcome study, P188 markedly alleviated brain atrophy and motor impairments and increased survival rate in 3 weeks of post stroke period. Additionally, P188 protected cultured hippucampal HT22 cells against oxygen-glucose deprivation and reoxygenation (OGD/R injury. The ability in membrane sealing was assessed with two fluorescent membrane-impermeant dyes. The results showed that P188 treatment significantly reduced the PI-positive cells following ischemia/reperfusion injury and repaired the HT22 cell membrane rupture induced by Triton X-100. In addition, P188 inhibited ischemia/reperfusion-induced activation of matrix metalloproteinase (MMP-9 and leakage of Evans blue. Therefore, the present study concludes that P188 can protect against cerebral ischemia/reperfusion injury, and the protection involves multi-mechanisms in addition to the membrane resealing.

  13. Multiscale modeling of blood flow: from single cells to blood rheology. (United States)

    Fedosov, Dmitry A; Noguchi, Hiroshi; Gompper, Gerhard


    Mesoscale simulations of blood flow, where the red blood cells are described as deformable closed shells with a membrane characterized by bending rigidity and stretching elasticity, have made much progress in recent years to predict the flow behavior of blood cells and other components in various flows. To numerically investigate blood flow and blood-related processes in complex geometries, a highly efficient simulation technique for the plasma and solutes is essential. In this review, we focus on the behavior of single and several cells in shear and microcapillary flows, the shear-thinning behavior of blood and its relation to the blood cell structure and interactions, margination of white blood cells and platelets, and modeling hematologic diseases and disorders. Comparisons of the simulation predictions with existing experimental results are made whenever possible, and generally very satisfactory agreement is obtained.


    NARCIS (Netherlands)



    In chronic hypoxemia blood flow and oxygen supply to vital organs are maintained, but to nonvital organs they are decreased. We measured organ blood flows (microspheres) and whole blood viscosity in 10 chronically hypoxemic lambs, with an atrial septal defect and pulmonary stenosis, and in 8 control

  15. Daily rhythm of cerebral blood flow velocity

    Directory of Open Access Journals (Sweden)

    Spielman Arthur J


    Full Text Available Abstract Background CBFV (cerebral blood flow velocity is lower in the morning than in the afternoon and evening. Two hypotheses have been proposed to explain the time of day changes in CBFV: 1 CBFV changes are due to sleep-associated processes or 2 time of day changes in CBFV are due to an endogenous circadian rhythm independent of sleep. The aim of this study was to examine CBFV over 30 hours of sustained wakefulness to determine whether CBFV exhibits fluctuations associated with time of day. Methods Eleven subjects underwent a modified constant routine protocol. CBFV from the middle cerebral artery was monitored by chronic recording of Transcranial Doppler (TCD ultrasonography. Other variables included core body temperature (CBT, end-tidal carbon dioxide (EtCO2, blood pressure, and heart rate. Salivary dim light melatonin onset (DLMO served as a measure of endogenous circadian phase position. Results A non-linear multiple regression, cosine fit analysis revealed that both the CBT and CBFV rhythm fit a 24 hour rhythm (R2 = 0.62 and R2 = 0.68, respectively. Circadian phase position of CBT occurred at 6:05 am while CBFV occurred at 12:02 pm, revealing a six hour, or 90 degree difference between these two rhythms (t = 4.9, df = 10, p Conclusion In conclusion, time of day variations in CBFV have an approximately 24 hour rhythm under constant conditions, suggesting regulation by a circadian oscillator. The 90 degree-phase angle difference between the CBT and CBFV rhythms may help explain previous findings of lower CBFV values in the morning. The phase difference occurs at a time period during which cognitive performance decrements have been observed and when both cardiovascular and cerebrovascular events occur more frequently. The mechanisms underlying this phase angle difference require further exploration.

  16. Data adaptive estimation of transversal blood flow velocities

    DEFF Research Database (Denmark)

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


    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......, posing natural difficulties due to the complex behaviour of blood flow, and due to the natural orientation of most blood vessels. Recently, a transversal modulation scheme was introduced to induce also an oscillation along the transversal direction, thereby allowing for the measurement of also...... 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....

  17. 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


    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......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...

  18. Prediction of Anomalous Blood Viscosity in Confined Shear Flow (United States)

    Thiébaud, Marine; Shen, Zaiyi; Harting, Jens; Misbah, Chaouqi


    Red blood cells play a major role in body metabolism by supplying oxygen from the microvasculature to different organs and tissues. Understanding blood flow properties in microcirculation is an essential step towards elucidating fundamental and practical issues. Numerical simulations of a blood model under a confined linear shear flow reveal that confinement markedly modifies the properties of blood flow. A nontrivial spatiotemporal organization of blood elements is shown to trigger hitherto unrevealed flow properties regarding the viscosity η, namely ample oscillations of its normalized value [η]=(η-η0)/(η0ϕ) as a function of hematocrit ϕ (η0=solvent viscosity). A scaling law for the viscosity as a function of hematocrit and confinement is proposed. This finding can contribute to the conception of new strategies to efficiently detect blood disorders, via in vitro diagnosis based on confined blood rheology. It also constitutes a contribution for a fundamental understanding of rheology of confined complex fluids.

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

    Energy Technology Data Exchange (ETDEWEB)

    Itoh, K.; Korogi, Y.; Tomiguchi, S.; Takahashi, M. [Dept. of Radiology, Kumamoto University School of Medicine (Japan); Okajima, T. [Dept. of Neurology, Johnan Hospital, Maihara, Johnan-mochi (Japan); Sato, H. [Dept. of Neurology, Minamata City General Hospital and Medical Centre (Japan)


    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.)

  20. Cerebellar blood flow in methylmercury poisoning (Minamata disease). (United States)

    Itoh, K; Korogi, Y; Tomiguchi, S; Takahashi, M; Okajima, T; Sato, H


    We looked at regional cerebellar blood flow in patients with Minamata disease (MD) using technetium-99m 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.

  1. El flujo como indicador del efecto terapéutico del ácido folínico en la isquemia-reperfusión Capillary blood flown as an index of the therapeutic effect of folinic acid in ischemia-reperfusion syndrome

    Directory of Open Access Journals (Sweden)

    J. San Cristóbal


    Full Text Available Objetivo: estudio sobre reperfusión intestinal con una doble finalidad: a valorar la utilidad de la medición del flujo capilar intestinal mediante láser-doppler para el estudio de la reperfusión intestinal; y b comparar el efecto de las formas racémica y levo del ácido folínico en su tratamiento. Diseño experimental: modelo murino de isquemia intestinal mediante clampaje completo de la arteria mesentérica superior durante 90 minutos. Se compara la evolución de tres grupos de tratamiento: suero salino, ácido folínico y ácido levofolínico. Se analiza la evolución de parámetros bioquímicos (niveles de creatín kinasa, láctico deshidrogenasa y fosfatasa alcalina a los 60 minutos y dos y siete días de restablecer el flujo sanguíneo, flujo capilar en yeyuno e íleon mediante láser-doppler (durante isquemia y tras primera hora de reperfusión, lesión mucosa intestinal, y curva de supervivencia. Resultados: el láser-doppler permitió analizar con fiabilidad el efecto de los tratamientos sobre el flujo capilar durante reperfusión intestinal. El ácido levofolínico mejoró el flujo capilar en el íleon a partir de los 25 minutos de reperfusión, a la vez que disminuyó la lesión mucosa en el mismo tramo intestinal el séptimo día de evolución (p Objective: an intestinal reperfusion study with two aims: a to assess the usefulness of intestinal capillary blood flow measurement by laser-Doppler for intestinal reperfusion studies; and b to compare the effects of racemic and levo forms of folinic acid in treating the syndrome. Experimental design: a murine model of intestinal ischemia by completely clamping the superior mesenteric artery for 90 minutes. A comparison was made of three treatment groups: saline, folinic acid, and levo-folinic acid. The following factors were analyzed: changes in biochemical parameters (levels of creatine kinase, lactic dehydrogenase, and alkaline phosphatase at 60 minutes, and at two and seven days

  2. Blood flow restricted exercise and vascular function. (United States)

    Horiuchi, Masahiro; Okita, Koichi


    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.

  3. Pulsatile blood flow in Abdominal Aortic Aneurysms (United States)

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


    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.

  4. Synthetic Capillaries to Control Microscopic Blood Flow (United States)

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


    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.

  5. Blood Flow Restricted Exercise and Vascular Function

    Directory of Open Access Journals (Sweden)

    Masahiro Horiuchi


    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.

  6. Effects of supplementing qi and activating blood circulation on piamatral microcirculation in gerbils with cerebral ischemic reperfusion%益气活血对脑缺血再灌注沙土鼠脑膜微循环的作用

    Institute of Scientific and Technical Information of China (English)

    俞国平; 戴良珏; 方敏; 谢荭


    position with an median incision made in the lateral cervical nucleus to isolate and expose bilateral common carotid artery (CCA). The bilateral CCA were occluded by atraumatic micro-bulldog clamp, and the occluded blood flow in the distal end was observed under the microscope. Thirty minutes after occlusion of bilateral CCA, the vascular clamp was unclamped to recover the cerebral blood reperfusion. Gerbils in the medicine group were abdominally injected with 0.4 mL of Huangqi injection (containing 0.8 g of crude drug), 0.3 mL of compound Danggui injection (containing Danggui, Chuanqiong and Honghua, 0.09 g for each)and 0.3 mL of Danshen injection (containing 0.45 g of Shengyao). Animals in the control group were abdominally injected with same-volume of normal saline. The changes of pial microcirculation were quantitatively observed in two groups through cranium window respectively before blockage, at the reperfusion after blockage as well as in 120 minutes after injection by laser microcirculation microscope and the TV video system.MAIN OUTCOME MEASURES: The changes of piamatral microcirculation as well as comparison in venous blood flow velocity in gerbils of each group before and after ischemic reperfusion.RESULTS: All gerbils were involved in the analysis of results with no animal died in the experiment.①When the CCA of animals in the two groups were blocked, obvious contraction of piamatral microcirculation was seen and partial blood vessels were blocked up. Platelet and red blood cells etc.adhered to the arteriolae of grade Ⅰ and veinules below grade Ⅲ with microthrombus formed and large ischemic area appeared. The blood flow rate was obviously slowed down. Moderate and severe aggregations were found in red blood cells, and the white blood cells were significantly increased.There was obvious exudation in the periphery of microvessels. After CCA reperfusion, the arteriolae and veinule were in different thickness, and the thrombus in veinule of grade Ⅰ and

  7. 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


    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...

  8. Glial and neuronal control of brain blood flow

    DEFF Research Database (Denmark)

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


    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...

  9. 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))


    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.

  10. Sex differences of human cortical blood flow and energy metabolism

    DEFF Research Database (Denmark)

    Aanerud, Joel; Borghammer, Per; Rodell, Anders


    cortex. Women had significant decreases of cerebral blood flow as function of age in frontal and parietal lobes. Young women had significantly higher cerebral blood flow than men in frontal and temporal lobes, but these differences had disappeared at age 65. The absent sex difference of cerebral energy...

  11. Regional cerebral blood flow in focal cortical epilepsy

    DEFF Research Database (Denmark)

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


    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 st...

  12. Subcutaneous blood flow during insulin-induced hypoglycaemia

    DEFF Research Database (Denmark)

    Hilsted, J; Madsbad, S; Sestoft, L


    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...

  13. Exploration of 4D MRI blood flow using stylistic visualization. (United States)

    van Pelt, Roy; Oliván Bescós, Javier; Breeuwer, Marcel; Clough, Rachel E; Gröller, M Eduard; ter Haar Romenij, Bart; Vilanova, Anna


    Insight into the dynamics of blood-flow considerably improves the understanding of the complex cardiovascular system and its pathologies. Advances in MRI technology enable acquisition of 4D blood-flow data, providing quantitative blood-flow velocities over time. The currently typical slice-by-slice analysis requires a full mental reconstruction of the unsteady blood-flow field, which is a tedious and highly challenging task, even for skilled physicians. We endeavor to alleviate this task by means of comprehensive visualization and interaction techniques. In this paper we present a framework for pre-clinical cardiovascular research, providing tools to both interactively explore the 4D blood-flow data and depict the essential blood-flow characteristics. The framework encompasses a variety of visualization styles, comprising illustrative techniques as well as improved methods from the established field of flow visualization. Each of the incorporated styles, including exploded planar reformats, flow-direction highlights, and arrow-trails, locally captures the blood-flow dynamics and may be initiated by an interactively probed vessel cross-section. Additionally, we present the results of an evaluation with domain experts, measuring the value of each of the visualization styles and related rendering parameters.

  14. The role of polymorphonudear cells in lung ischemia-reperfusion injury in a canine model of pulmonary thromboembolism

    Institute of Scientific and Technical Information of China (English)



    Objective To explore the effects of polymoronuclear cells (PMN) on lung ischemia-reperfusion(I/R) injury in a canine model of pulmonary thromboembolism. Methods Fifteen dogs were divided into three groups; a sham group (n=5), an ischemia group (n=5) and a reperfusion group (n=5). PMN in the whole blood were isolated with density gradient centrifugation. Apoptosis rate of the PMN was measured through flow cytome-

  15. 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


    @@ 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.

  16. Blood flow controls bone vascular function and osteogenesis (United States)

    Ramasamy, Saravana K.; Kusumbe, Anjali P.; Schiller, Maria; Zeuschner, Dagmar; Bixel, M. Gabriele; Milia, Carlo; Gamrekelashvili, Jaba; Limbourg, Anne; Medvinsky, Alexander; Santoro, Massimo M.; Limbourg, Florian P.; Adams, Ralf H.


    While blood vessels play important roles in bone homeostasis and repair, fundamental aspects of vascular function in the skeletal system remain poorly understood. Here we show that the long bone vasculature generates a peculiar flow pattern, which is important for proper angiogenesis. Intravital imaging reveals that vessel growth in murine long bone involves the extension and anastomotic fusion of endothelial buds. Impaired blood flow leads to defective angiogenesis and osteogenesis, and downregulation of Notch signalling in endothelial cells. In aged mice, skeletal blood flow and endothelial Notch activity are also reduced leading to decreased angiogenesis and osteogenesis, which is reverted by genetic reactivation of Notch. Blood flow and angiogenesis in aged mice are also enhanced on administration of bisphosphonate, a class of drugs frequently used for the treatment of osteoporosis. We propose that blood flow and endothelial Notch signalling are key factors controlling ageing processes in the skeletal system. PMID:27922003

  17. Mammary blood flow regulation in the nursing rabbit

    Energy Technology Data Exchange (ETDEWEB)

    Katz, M.; Creasy, R.K.


    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.

  18. Ultrasonic Doppler measurement of renal artery blood flow (United States)

    Freund, W. R.; Beaver, W. L.; Meindl, J. D.


    Studies were made of (1) blood flow redistribution during lower body negative pressure (LBNP), (2) the profile of blood flow across the mitral annulus of the heart (both perpendicular and parallel to the commissures), (3) testing and evaluation of a number of pulsed Doppler systems, (4) acute calibration of perivascular Doppler transducers, (5) redesign of the mitral flow transducers to improve reliability and ease of construction, and (6) a frequency offset generator designed for use in distinguishing forward and reverse components of blood flow by producing frequencies above and below the offset frequency. Finally methodology was developed and initial results were obtained from a computer analysis of time-varying Doppler spectra.


    Institute of Scientific and Technical Information of China (English)

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


    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.

  20. Micro-PIV measurements of blood flow in extraembryonic blood vessels of chicken embryos. (United States)

    Lee, Jung Yeop; Ji, Ho Seong; Lee, Sang Joon


    The hemodynamic characteristics of blood flow are important in the diagnosis of circulatory diseases, since such diseases are related to wall shear stress of cardiovascular vessels. In chicken embryos at early stages of development, it is possible to directly visualize blood flow inside blood vessels. We therefore employed a micro-PIV technique to assess blood flow in extraembryonic venous and arterial blood vessels of chicken embryos, using red blood cells (RBCs) as tracers and obtaining flow images of RBCs using a high-speed CMOS camera. The mean velocity field showed non-Newtonian flow characteristics. The blood flow in two venous vessels merged smoothly into the Y-shaped downstream vein without any flow separation or secondary flow. Vorticity was high in the inner regions, where the radius of curvature varied greatly. A periodic variation of temporally resolved velocity signals, due to beating of the heart, was observed in arterial blood vessels. The pulsating frequency was obtained by fast Fourier transform analysis using the measured velocity data. The measurement technique used here was useful in analyzing the hemodynamic characteristics of in vivo blood flow in chicken embryos.

  1. Effect of intestinal ischemia-reperfusion injury on protein levels of leptin and orexin-A in peripheral blood and central secretory tissues

    Institute of Scientific and Technical Information of China (English)

    Ji Lin; Guang-Tao Yan; Xiu-Hua Hao; Lu-Huan Wang; Kai Zhang; Hui Xue


    AIM: To explore the effect of intestinal ischemia-reperfusion injury on protein levels of leptin and orexin-A in peripheral blood and their central secretory tissues and to find out the role leptin and orexin-A play in acute inflammatory responses.METHODS: An intestinal ischemia-reperfusion (I/R)injury model of rats was established and rats were divided randomly into six groups: sham-operation group, 60 min ischemia/30 min reperfusion group (I60'R30'), I60'R90',I60'R150', I60'R240' and I60'R360', 9 rats each group.Two highly-sensitive radioimmunoassays for leptin and orexin-A were established and used to check the change of their concentrations in peripheral blood and central secretory tissues before and after intestinal I/R injury.RESULTS: Compared with the serum leptin level before injury, it decreased significantly in I60'R30' group and increased significantly in I60'R360' group; compared to sham-operation group after injury, serum leptin level increased significantly in I60'R360' group; compared to sham-operation group after injury, adipose leptin levels decreased significantly in I60'R30' and I60'R90' groups,while increased significantly in I60'R360' group. There was no significant difference between the expression levels of orexin-A before and after I/R injury.CONCLUSION: Leptin has a time-dependent response and orexin-A has a delayed response to acute inflammatory stimuli such as intestinal I/R injury and they may participate in metabolic disorders in injury as inflammatory cytokines.

  2. 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;


    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...

  3. Cerebral blood flow and metabolism during sleep. (United States)

    Madsen, P L; Vorstrup, S


    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 data indicate that global levels of CBF and CMR are about the same during REM sleep as in wakefulness. On the regional level, deep sleep seems to be associated with a uniform decrease in regional CBF and CMR. Investigations concerning regional CBF and CMR during REM sleep are few but data from recent investigations seem to identify site-specific changes in regional CBF and CMR during REM sleep. CBF and CMR are reflections of cerebral synaptic activity and the magnitude of reduction in these variables associated with deep sleep indicates that overall cerebral synaptic activity is reduced to approximately one-half the level associated with wakefulness, while cerebral synaptic activity levels during REM sleep are similar to wakefulness. However, even though the new understanding of CBF and CMR during sleep provides significant and important information of the brain's mode of working during sleep, it does not at its current state identify the physiological processes involved in sleep or the physiological role of sleep.

  4. Dynamics of blood flow in a microfluidic ladder network (United States)

    Maddala, Jeevan; Zilberman-Rudenko, Jevgenia; McCarty, Owen

    The dynamics of a complex mixture of cells and proteins, such as blood, in perturbed shear flow remains ill-defined. Microfluidics is a promising technology for improving the understanding of blood flow under complex conditions of shear; as found in stent implants and in tortuous blood vessels. We model the fluid dynamics of blood flow in a microfluidic ladder network with dimensions mimicking venules. Interaction of blood cells was modeled using multiagent framework, where cells of different diameters were treated as spheres. This model served as the basis for predicting transition regions, collision pathways, re-circulation zones and residence times of cells dependent on their diameters and device architecture. Based on these insights from the model, we were able to predict the clot formation configurations at various locations in the device. These predictions were supported by the experiments using whole blood. To facilitate platelet aggregation, the devices were coated with fibrillar collagen and tissue factor. Blood was perfused through the microfluidic device for 9 min at a physiologically relevant venous shear rate of 600 s-1. Using fluorescent microscopy, we observed flow transitions near the channel intersections and at the areas of blood flow obstruction, which promoted larger thrombus formation. This study of integrating model predictions with experimental design, aids in defining the dynamics of blood flow in microvasculature and in development of novel biomedical devices.

  5. Regional patterns of cortical blood flow distinguish extraverts from introverts


    Stenberg, Georg; Risberg, Jarl; Warkentin, S.; Rosén, Ingmar


    Eysenck's hypothesis of higher cortical arousal in introverts was examined using regional cerebral blood flow measurement in 37 healthy subjects . The measurement was made at rest, using the133Xe-inhalation method. Estimates of gray matter flow were obtained for 32 brain regions. There was no significant evidence of personality differences in general arousal, as measured by the mean flow level, averaged over all regions. There were, however, regional differences. An overall test of the blood ...

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

    NARCIS (Netherlands)

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

    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

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

    NARCIS (Netherlands)

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


    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

  8. Assessment of skin flaps using optically based methods for measuring blood flow and oxygenation. (United States)

    Payette, Jeri R; Kohlenberg, Elicia; Leonardi, Lorenzo; Pabbies, Arone; Kerr, Paul; Liu, Kan-Zhi; Sowa, Michael G


    The objective of this study was to compare two noninvasive techniques, laser Doppler and optical spectroscopy, for monitoring hemodynamic changes in skin flaps. Animal models for assessing these changes in microvascular free flaps and pedicle flaps were investigated. A 2 x 3-cm free flap model based on the epigastric vein-artery pair and a reversed MacFarlane 3 x 10-cm pedicle flap model were used in this study. Animals were divided into four groups, with groups 1 (n = 6) and 2 (n = 4) undergoing epigastric free flap surgery and groups 3 (n = 3) and 4 (n = 10) undergoing pedicle flap surgery. Groups 1 and 4 served as controls for each of the flap models. Groups 2 and 3 served as ischemia-reperfusion models. Optical spectroscopy provides a measure of hemoglobin oxygen saturation and blood volume, and the laser Doppler method measures blood flow. Optical spectroscopy proved to be consistently more reliable in detecting problems with arterial in flow compared with laser Doppler assessments. When spectroscopy was used in an imaging configuration, oxygen saturation images of the entire flap were generated, thus creating a visual picture of global flap health. In both single-point and imaging modes the technique was sensitive to vessel manipulation, with the immediate post operative images providing an accurate prediction of eventual outcome. This series of skin flap studies suggests a potential role for optical spectroscopy and spectroscopic imaging in the clinical assessment of skin flaps.


    Institute of Scientific and Technical Information of China (English)


    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.

  10. The effect of hyperosmotic solutions on the hepatic blood flow

    DEFF Research Database (Denmark)

    Winkler, K; Henriksen, Jens Henrik; Tygstrup, N


    The present study was undertaken in order to measure the effect of hyperosmotic solutions on portal and hepatic blood flow. In five anaesthetized pigs without arterial blood supply to the liver, portal blood flow rate was measured (electromagnetic flowmeter) during 5 min lasting intravenous...... infusions of hyperosmotic galactose (50%, 84-100 ml) and mannitol (25%, 100 ml), with physiological saline (100 ml) as control. Portal blood flow increased to a peak value of (39% [P = 0.06] galactose and 37%, [P = 0.06], mannitol) soon after stop of the hyperosmotic infusion. For galactose the change ended...... somewhat earlier than for mannitol. Saline induced a minor increase (15%). Similarly, increments of, on average, 144% of the hepatic blood flow rate was seen in six patients with cirrhosis, following infusion of hyperosmotic galactose, the increase being more pronounced than in the pigs. The causes...

  11. Propofol post-conditioning protects the blood brain barrier by decreasing matrix metalloproteinase-9 and aquaporin-4 expression and improves the neurobehavioral outcome in a rat model of focal cerebral ischemia-reperfusion injury. (United States)

    Ji, Feng-Tao; Liang, Jian-Jun; Miao, Li-Ping; Wu, Qiang; Cao, Ming-Hui


    Propofol, an intravenous anesthetic, inhibits neuronal apoptosis induced by ischemic stroke, protects the brain from ischemia/reperfusion injury and improves neuronal function. However, whether propofol is able to protect the blood brain barrier (BBB) and the underlying mechanisms have remained to be elucidated. In the present study, a rat model of cerebral ischemia/reperfusion was established, using a thread embolism to achieve middle cerebral artery occlusion. Rats were treated with propofol (propofol post-conditioning) or physiological saline (control) administered by intravenous injection 30 min following reperfusion. Twenty-four hours following reperfusion, neurobehavioral manifestations were assessed. The levels of cephaloedema, damage to the BBB and expression levels of matrix metalloproteinase-9 (MMP-9), aquaporin-4 (AQP-4) and phosphorylated c-Jun N-terminal kinase (pJNK) were determined in order to evaluate the effects of propofol on the BBB. In comparison to the cerebral ischemia/reperfusion group, the levels of brain water content and Evans blue content, as well as the expression levels of MMP-9, AQP-4 and pJNK were significantly reduced in the propofol post-conditioning group. These results indicated that propofol post-conditioning improved the neurobehavioral manifestations and attenuated the BBB damage and cephaloedema induced following cerebral ischemia/reperfusion. This effect may be due to the inhibition of MMP-9 and AQP-4 expression, and the concurrent decrease in JNK phosphorylation.

  12. Effects of non Newtonian spiral blood flow through arterial stenosis (United States)

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


    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.

  13. Mesenteric, coeliac and splanchnic blood flow in humans during exercise

    DEFF Research Database (Denmark)

    Perko, M J; Nielsen, H B; Skak, C


    blood flow as assessed by the Indocyanine Green dye-elimination technique. 3. Cycling increased arterial pressure, heart rate and cardiac output, while it reduced total vascular resistance. These responses were not altered in the postprandial state. During fasting, cycling increased mesenteric, coeliac......1. Exercise reduces splanchnic blood flow, but the mesenteric contribution to this response is uncertain. 2. In nineteen humans, superior mesenteric and coeliac artery flows were determined by duplex ultrasonography during fasting and postprandial submaximal cycling and compared with the splanchnic...... decreased by 51 and 31 % (0.49 +/- 0.07 and 0.96 +/- 0.28 l min-1). Splanchnic blood flow values assessed by duplex ultrasound and by dye-elimination techniques were correlated (r = 0.70; P exercise in humans, splanchnic resistance increases and blood flow is reduced following...

  14. Mesenteric, coeliac and splanchnic blood flow in humans during exercise

    DEFF Research Database (Denmark)

    Perko, M J; Nielsen, H B; Skak, C;


    1. Exercise reduces splanchnic blood flow, but the mesenteric contribution to this response is uncertain. 2. In nineteen humans, superior mesenteric and coeliac artery flows were determined by duplex ultrasonography during fasting and postprandial submaximal cycling and compared with the splanchnic...... blood flow as assessed by the Indocyanine Green dye-elimination technique. 3. Cycling increased arterial pressure, heart rate and cardiac output, while it reduced total vascular resistance. These responses were not altered in the postprandial state. During fasting, cycling increased mesenteric, coeliac...... and splanchnic resistances by 76, 165 and 126 %, respectively, and it reduced corresponding blood flows by 32, 50 and 43 % (by 0.18 +/- 0.04, 0.42 +/- 0.03 and 0.60 +/- 0.04 l min-1). Postprandially, mesenteric and splanchnic vascular resistances decreased, thereby elevating regional blood flow, while...

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

    DEFF Research Database (Denmark)

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


    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...

  16. Excitatory amino acid changes in the brains of rhesus monkeys following selective cerebral deep hypothermia and blood flow occlusion

    Institute of Scientific and Technical Information of China (English)

    Jun Pu; Xiaoqun Niu; Jizong Zhao


    Selective cerebral deep hypothermia and blood flow occlusion can enhance brain tolerance to ischemia and hypoxia and reduce cardiopulmonary complications in monkeys. Excitotoxicity induced by the release of a large amount of excitatory amino acids after cerebral ischemia is the major mechanism underlying ischemic brain injury and nerve cell death. In the present study, we used selective cerebral deep hypothermia and blood flow occlusion to block the bilateral common carotid arteries and/or bilateral vertebral arteries in rhesus monkey, followed by reperfusion using Ringer's solution at 4°C. Microdialysis and transmission electron microscope results showed that selective cerebral deep hypothermia and blood flow occlusion inhibited the release of glutamic acid into the extracellular fluid in the brain frontal lobe and relieved pathological injury in terms of the ultrastructure of brain tissues after severe cerebral ischemia. These findings indicate that cerebral deep hypothermia and blood flow occlusion can inhibit cytotoxic effects and attenuate ischemic/ hypoxic brain injury through decreasing the release of excitatory amino acids, such as glutamic acid.

  17. Modified Beer-Lambert law for blood flow (United States)

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


    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.

  18. Spontaneous oscillations of capillary blood flow in artificial microvascular networks. (United States)

    Forouzan, Omid; Yang, Xiaoxi; Sosa, Jose M; Burns, Jennie M; Shevkoplyas, Sergey S


    Previous computational studies have suggested that the capillary blood flow oscillations frequently observed in vivo can originate spontaneously from the non-linear rheological properties of blood, without any regulatory input. Testing this hypothesis definitively in experiments involving real microvasculature has been difficult because in vivo the blood flow in capillaries is always actively controlled by the host. The objective of this study was to test the hypothesis experimentally and to investigate the relative contribution of different blood cells to the capillary blood flow dynamics under static boundary conditions and in complete isolation from the active regulatory mechanisms mediated by the blood vessels in vivo. To accomplish this objective, we passed whole blood and re-constituted blood samples (purified red blood cells suspended in buffer or in autologous plasma) through an artificial microvascular network (AMVN) comprising completely inert, microfabricated vessels with the architecture inspired by the real microvasculature. We found that the flow of blood in capillaries of the AMVN indeed oscillates with characteristic frequencies in the range of 0-0.6 Hz, which is in a very good agreement with previous computational studies and in vivo observations. We also found that the traffic of leukocytes through the network (typically neglected in computational modeling) plays an important role in generating the oscillations. This study represents the key piece of experimental evidence in support of the hypothesis that spontaneous, self-sustained oscillations of capillary blood flow can be generated solely by the non-linear rheological properties of blood flowing through microvascular networks, and provides an insight into the mechanism of this fundamentally important microcirculatory phenomenon.

  19. Granulocyte-Colony Stimulating Factor Increases Cerebral Blood Flow via a NO Surge Mediated by Akt/eNOS Pathway to Reduce Ischemic Injury

    Directory of Open Access Journals (Sweden)

    Hock-Kean Liew


    Full Text Available Granulocyte-colony stimulating factor (G-CSF protects brain from ischemic/reperfusion (I/R injury, and inhibition of nitric oxide (NO synthases partially reduces G-CSF protection. We thus further investigated the effects of G-CSF on ischemia-induced NO production and its consequence on regional cerebral blood flow (rCBF and neurological deficit. Endothelin-1 (ET-1 microinfused above middle cerebral artery caused a rapid reduction of rCBF (ischemia which lasted for 30 minutes and was followed by a gradual recovery of blood flow (reperfusion within the striatal region. Regional NO concentration increased rapidly (NO surge during ischemia and recovered soon to the baseline. G-CSF increased rCBF resulting in shorter ischemic duration and an earlier onset of reperfusion. The enhancement of the ischemia-induced NO by G-CSF accompanied by elevation of phospho-Akt and phospho-eNOS was noted, suggesting an activation of Akt/eNOS. I/R-induced infarct volume and neurological deficits were also reduced by G-CSF treatment. Inhibition of NO synthesis by L-NG-Nitroarginine Methyl Ester (L-NAME significantly reduced the effects of G-CSF on rCBF, NO surge, infarct volume, and neurological deficits. We conclude that G-CSF increases rCBF through a NO surge mediated by Akt/eNOS, which partially contributes to the beneficial effect of G-CSF on brain I/R injury.


    Institute of Scientific and Technical Information of China (English)

    LIUZhao-rong; XUGang; CHENYong; TENGZhong0=zhao; QINKai-rong


    Blood flow in artery was treated as the flow under equilibriums state(the steady flow under mean pressure)combined with the periodically small pulsatile flow.Using vascular strain energy function advanced by Fung,the vascular stress-strain relationship under equilibrium state was analyzed and the circumferential and axial elastic moduli were deduced that are expressed while the arterial strains around the equilibrium state are relatively small,so that the equations of vesse wall motion under the pulsatile pressure could be established here.Through solving both the vessel equations and the linear Navier-Stokes equations,the analytic expressions of the blood flow velocities and the vascular displacements were obtained.The influence of the difference between vascular circumferentia and axial elasticities on pulsatile blood flow and vascular motion was discussed in details.


    Institute of Scientific and Technical Information of China (English)

    柳兆荣; 徐刚; 陈泳; 滕忠照; 覃开蓉


    Blood flow in artery was treated as the flow under equilibrium state ( the steady flow under mean pressure ) combined with the periodically small pulsatile flow. Using vascular strain energy function advanced by Fung, the vascular stress-strain relationship under equilibrium state was analyzed and the circumferential and axial elastic moduli were deduced that are expressed while the arterial strains around the equilibrium state are relatively small, so that the equations of vessel wall motion under the pulsatile pressure could be established here. Through solving both the vessel equations and the linear NavierStokes equations, the analytic expressions of the blood flow velocities and the vascular displacements were obtained. The influence of the difference between vascular circumferential and axial elasticities on pulsatile blood flow and vascular motion was discussed in details.

  2. The effect of hyperglycemia on blood brain barrier of rats with focal cerebral ischemia/reperfusion injury

    Institute of Scientific and Technical Information of China (English)


    Objective: To determine whether hyperglycemia could aggravate the microvascular damage in ischemic stroke.Methods: Hyperglycemia model was made by injection of streptozocin through subcutaneous injection in wistar rats. Using the suture model, the rats were subjected to 3 h of focal ischemia and different times of reperfusion,including 6,12,24,48,96 h and 7 d. TTC dyeing was used to show the infarction area of rats. The infarctive volume of rats were calculated by computer imaging analysis system;Matrix metalloproteinase (MMP-2) and (MMP-9)were detected by immunohistochemistry and in situ hybridization histochemistry in Wistar rats.Results: The infarctive volume was siginificantly larger in hyperglycemic rats than that of nonhyperglycemic rats. The level of MMP-2,MMP-9 expression in the group of hyperglycemic rats was higher than that of nonhyperglycemic rats. Conclusion: Hyperglycemia aggravated the injury of focal ischmia-reperfusion in wistar rats and the higher expression of MMP-2, MMP-9 might be one of the mechanism in aggravation of focal ischemia/reperfusion injury.

  3. Regulation of exercise blood flow: Role of free radicals. (United States)

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


    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.

  4. Dietary Virgin Olive Oil Reduces Blood Brain Barrier Permeability, Brain Edema, and Brain Injury in Rats Subjected to Ischemia-Reperfusion

    Directory of Open Access Journals (Sweden)

    Fatemeh Mohagheghi


    Full Text Available Recent studies suggest that dietary virgin olive oil (VOO reduces hypoxia-reoxygenation injury in rat brain slices. We sought to extend these observations in an in vivo study of rat cerebral ischemia-reperfusion injury. Four groups, each consisting of 18 Wistar rats, were studied. One group (control received saline, while three treatment groups received oral VOO (0.25, 0.5, and 0.75 mL/kg/day, respectively. After 30 days, blood lipid profiles were determined, before a 60-min period of middle cerebral artery occlusion (MCAO. After 24-h reperfusion, neurological deficit scores, infarct volume, brain edema, and blood brain barrier permeability were each assessed in subgroups of six animals drawn from each main group. VOO reduced the LDL/HDL ratio in doses of 0.25, 0.5, and 0.75 mL/kg/day in comparison to the control group (p < 0.05, and offered cerebroprotection from ischemia-reperfusion. For controls vs. doses of 0.25 vs. 0.5 vs. 0.75 mL/kg/day, attenuated corrected infarct volumes were 207.82 ± 34.29 vs. 206.41 ± 26.23 vs. 124.21 ± 14.73 vs. 108.46 ± 31.63 mm3; brain water content of the infarcted hemisphere was 82 ±± 0.25 vs. 81.5 ± 0.56 vs. 80.5 ± 0.22 vs. 80.5 ± 0.34%; and blood brain barrier permeability of the infarcted hemisphere was 11.31 ± 2.67 vs. 9.21 ± 2.28 vs. 5.83 ± 1.6 vs. 4.43 ± 0.93 µg/g tissue (p < 0.05 for measures in doses 0.5 and 0.75 mL/kg/day vs. controls. Oral administration of VOO reduces infarct volume, brain edema, blood brain barrier permeability, and improves neurologic deficit scores after transient MCAO in rats.

  5. Reperfusion injury and reactive oxygen species: The evolution of a concept☆ (United States)

    Granger, D. Neil; Kvietys, Peter R.


    Reperfusion injury, the paradoxical tissue response that is manifested by blood flow-deprived and oxygen-starved organs following the restoration of blood flow and tissue oxygenation, has been a focus of basic and clinical research for over 4-decades. While a variety of molecular mechanisms have been proposed to explain this phenomenon, excess production of reactive oxygen species (ROS) continues to receive much attention as a critical factor in the genesis of reperfusion injury. As a consequence, considerable effort has been devoted to identifying the dominant cellular and enzymatic sources of excess ROS production following ischemia-reperfusion (I/R). Of the potential ROS sources described to date, xanthine oxidase, NADPH oxidase (Nox), mitochondria, and uncoupled nitric oxide synthase have gained a status as the most likely contributors to reperfusion-induced oxidative stress and represent priority targets for therapeutic intervention against reperfusion-induced organ dysfunction and tissue damage. Although all four enzymatic sources are present in most tissues and are likely to play some role in reperfusion injury, priority and emphasis has been given to specific ROS sources that are enriched in certain tissues, such as xanthine oxidase in the gastrointestinal tract and mitochondria in the metabolically active heart and brain. The possibility that multiple ROS sources contribute to reperfusion injury in most tissues is supported by evidence demonstrating that redox-signaling enables ROS produced by one enzymatic source (e.g., Nox) to activate and enhance ROS production by a second source (e.g., mitochondria). This review provides a synopsis of the evidence implicating ROS in reperfusion injury, the clinical implications of this phenomenon, and summarizes current understanding of the four most frequently invoked enzymatic sources of ROS production in post-ischemic tissue. PMID:26484802

  6. Large-Eddy simulation of pulsatile blood flow. (United States)

    Paul, Manosh C; Mamun Molla, Md; Roditi, Giles


    Large-Eddy simulation (LES) is performed to study pulsatile blood flow through a 3D model of arterial stenosis. The model is chosen as a simple channel with a biological type stenosis formed on the top wall. A sinusoidal non-additive type pulsation is assumed at the inlet of the model to generate time dependent oscillating flow in the channel and the Reynolds number of 1200, based on the channel height and the bulk velocity, is chosen in the simulations. We investigate in detail the transition-to-turbulent phenomena of the non-additive pulsatile blood flow downstream of the stenosis. Results show that the high level of flow recirculation associated with complex patterns of transient blood flow have a significant contribution to the generation of the turbulent fluctuations found in the post-stenosis region. The importance of using LES in modelling pulsatile blood flow is also assessed in the paper through the prediction of its sub-grid scale contributions. In addition, some important results of the flow physics are achieved from the simulations, these are presented in the paper in terms of blood flow velocity, pressure distribution, vortices, shear stress, turbulent fluctuations and energy spectra, along with their importance to the relevant medical pathophysiology.

  7. Study Links Stuttering to Less Blood Flow in Brain (United States)

    ... Study Links Stuttering to Less Blood Flow in Brain The more ... to speech may put people at risk for stuttering, a small study suggests. There are also signs ...

  8. Skeletal Blood Flow in Bone Repair and Maintenance

    Institute of Scientific and Technical Information of China (English)

    Ryan E.Tomlinson; Matthew J.Silva


    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.

  9. Reduced myocardial blood flow in acute and chronic digitalization. (United States)

    Steiness, E; Bille-Brahe, N E; Hansen, J F; Lomholt, N; Ring-Larsen, H


    The myocardial blood flow was measured by the 133Xenon disappearance curve from the left ventricular wall following an injection of 133Xenon in the left coronary artery in 8 dogs without digoxin pretreatment and in 8 chronically digitalized dogs. The myocardial blood flow was significantly less (30%) in the digitalized dogs than in the dogs without pretreatment. In the digitalized dogs as well as in those without pretreatment an intravenous injection of digoxin resulted in a further significant decrease of the myocardial blood flow of about 20% and a significant increase of the coronary vascular resistance. The reduced myocardial blood flow both during acute and chronic digitalization is beleived to be of clinical importance.

  10. Salt-gland secretion and blood flow in the goose. (United States)

    Hanwell, A; Linzell, J L; Peaker, M


    1. Salt-gland blood flow in the domestic goose has been measured using a combination of Sapirstein's indicator fractionation technique for organ blood flow and Fegler's thermodilution method for cardiac output.2. Nasal salt secretion was induced by giving 0.5 M-NaCl or 0.154 M-NaCl I.V. or by giving artificial sea water by stomach tube into the proventriculus.3. During secretion, salt-gland blood flow increased from 82.7 +/- 21.9 ml./100 g tissue. min to as high as 2179 ml./100 g. min (mean 1209 +/- 140).4. The rate of secretion in response to salt loading was very variable and was not correlated with the rate of blood flow.5. From the data obtained, it could be calculated that the median values for the percentage extraction of ions from the arterial plasma were Na 15%, K 35%, Cl 21% and water 5.8%.6. Atropine abolished secretion but not the increase in blood flow produced by salt loading.7. Unilateral complete denervation abolished secretion from and the increase in blood flow through the operated but not the control gland.8. Anaesthesia, induced by pentobarbitone sodium, almost completely blocked secretion and the increase in blood flow in the salt-gland in response to salt loading.9. In geese given 0.5 or 0.154 M-NaCl I.V. a positive, significant correlation was found between the total amount of nasal secretion collected over 30 min and the concentrations of Na and Cl in the nasal fluid. However, when the time course of secretion was followed in any one bird, the rate of secretion was inversely related to the concentrations of Na and Cl.10. Harderian gland blood flow was not affected by salt loading.

  11. Blood flow rate measurements with indicator techniques revisited

    DEFF Research Database (Denmark)

    Sejrsen, Per; Bülow, Jens


    In view of the emerging role, disturbances in regional blood flow rate seem to play in the pathogenesis of the metabolic syndrome; we review the concepts of the classical indicator dilution and washout techniques used for determinations of regional blood flow rate. Prerequisites, assumptions......, necessary precautions for the application of these experimental techniques are emphasized. Special attention has been carried out to elucidate the consequence of a choice of indicators having a large distribution volume in the tissues....

  12. Current Imaging Modalities for assessing Ocular Blood Flow in Glaucoma


    Mohindroo, Chirayu; Ichhpujani, Parul; Kumar, Suresh


    Glaucoma may be caused by an interplay of elevated intraocular pressure (IOP), vascular, genetic, anatomical, brain, and immune factors. The direct assessment of ocular hemodynam-ics offers promise for glaucoma detection, differentiation, and possibly new treatment modalities. All the methods currently in use to measure ocular blood flow have inherent limitations and measure different aspects of ocular blood flow. This review article attempts to provide detailed information on ocular perfu-si...

  13. Functional Doppler optical coherence tomography for cortical blood flow imaging (United States)

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


    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.

  14. Blood flow and microdialysis in the human femoral head

    DEFF Research Database (Denmark)

    Bøgehøj, Morten; Emmeluth, Claus; Overgaard, Søren


    BACKGROUND: If it would be possible to detect lack of flow and/or the development of ischemia in bone, we might have a way of predicting whether a broken bone will heal. We established microdialysis (MD) and laser Doppler (LD) flow measurement in the human femoral head in order to be able to detect...... ischemia and measure changes in blood flow. MATERIAL AND METHODS: In 9 patients undergoing total hip arthroplasty for primary osteoarthrosis, two MD catheters were inserted into the femoral head through two drill holes after the blood flow had been visualized by LD. Then primary samples were collected...... detected within 2 h of cessation of blood flow in most patients....


    Energy Technology Data Exchange (ETDEWEB)

    Massoudi, Mehrdad; Kim, Jeongho; Hund, Samuel J.; Antaki, James F.


    Micro-scale investigations of the flow and deformation of blood and its formed elements have been studied for many years. Early in vitro investigations in the rotational viscometers or small glass tubes revealed important rheological properties such as the reduced blood apparent viscosity, Fahraeus effect and Fahraeus-Lindqvist effect [1], exhibiting the nonhomogeneous property of blood in microcirculation. We have applied Mixture Theory, also known as Theory of Interacting Continua, to study and model this property of blood [2, 3]. This approach holds great promise for predicting the trafficking of RBCs in micro-scale flows (such as the depletion layer near the wall), and other unique hemorheological phenomena relevant to blood trauma. The blood is assumed to be composed of an RBC component modeled as a nonlinear fluid, suspended in plasma, modeled as a linearly viscous fluid.

  16. Experimental comparison of mammalian and avian blood flow in microchannels (United States)

    Fink, Kathryn; Liepmann, Dorian


    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.

  17. Establishing the diffuse correlation spectroscopy signal relationship with blood flow. (United States)

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


    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.

  18. Stochastic modeling for magnetic resonance quantification of myocardial blood flow (United States)

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


    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.

  19. Hepatic and intestinal blood flow following thermal injury

    Energy Technology Data Exchange (ETDEWEB)

    Carter, E.A.; Tompkins, R.G.; Burke, J.F.


    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.

  20. Ultrafast Ultrasound Imaging of Ocular Anatomy and Blood Flow (United States)

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


    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

  1. Radiohalogenated thienylethylamine derivatives for evaluating local cerebral blood flow (United States)

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


    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.

  2. Femoral Blood Flow and Cardiac Output During Blood Flow Restricted Leg Press Exercise (United States)

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


    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

  3. Microvascular blood flow resistance: Role of red blood cell migration and dispersion. (United States)

    Katanov, Dinar; Gompper, Gerhard; Fedosov, Dmitry A


    Microvascular blood flow resistance has a strong impact on cardiovascular function and tissue perfusion. The flow resistance in microcirculation is governed by flow behavior of blood through a complex network of vessels, where the distribution of red blood cells across vessel cross-sections may be significantly distorted at vessel bifurcations and junctions. In this paper, the development of blood flow and its resistance starting from a dispersed configuration of red blood cells is investigated in simulations for different hematocrit levels, flow rates, vessel diameters, and aggregation interactions between red blood cells. Initially dispersed red blood cells migrate toward the vessel center leading to the formation of a cell-free layer near the wall and to a decrease of the flow resistance. The development of cell-free layer appears to be nearly universal when scaled with a characteristic shear rate of the flow. The universality allows an estimation of the length of a vessel required for full flow development, lc ≲ 25D, for vessel diameters in the range 10 μm red blood cell dispersion at vessel bifurcations and junctions on the flow resistance may be significant in vessels which are shorter or comparable to the length lc. Aggregation interactions between red blood cells generally lead to a reduction of blood flow resistance. The simulations are performed using the same viscosity for both external and internal fluids and the RBC membrane viscosity is not considered; however, we discuss how the viscosity contrast may affect the results. Finally, we develop a simple theoretical model which is able to describe the converged cell-free-layer thickness at steady-state flow with respect to flow rate. The model is based on the balance between a lift force on red blood cells due to cell-wall hydrodynamic interactions and shear-induced effective pressure due to cell-cell interactions in flow. We expect that these results can also be used to better understand the flow

  4. 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.

  5. Methods for measurement of cerebral blood flow in man

    DEFF Research Database (Denmark)

    Lassen, N A


    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 all...

  6. Blood Flow through an Open-Celled Foam (United States)

    Ortega, Jason; Maitland, Duncan


    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.

  7. A multiple disk centrifugal pump as a blood flow device. (United States)

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


    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.

  8. Coded ultrasound for blood flow estimation using subband processing

    DEFF Research Database (Denmark)

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


    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...... was carried out using an experimental ultrasound scanner and a commercial linear array 7 MHz transducer. A circulating flow rig was scanned with a beam-to-flow angle of 60 degrees. The flow in the rig was laminar and had a parabolic flow-profile with a peak velocity of 0.09 m/s. The mean relative standard...

  9. Ultrasonic Imaging of Hemodynamic Force in Carotid Blood Flow (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.

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

    DEFF Research Database (Denmark)

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


    that neuronal activity and the neurotransmitter glutamate evoke the release of messengers that dilate capillaries by actively relaxing pericytes. Dilation is mediated by prostaglandin E2, but requires nitric oxide release to suppress vasoconstricting 20-HETE synthesis. In vivo, when sensory input increases......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...

  11. Abnormality in cerebellar blood flow in solo vertigo patients

    Energy Technology Data Exchange (ETDEWEB)

    Nagahori, Takeshi [Shakaihoken Takaoka Hospital, Toyama (Japan); Nishijima, Michiharu; Endo, Shunro; Takaku, Akira


    Little is known about the blood flow of the vertebrobasilar system as a cause of vertigo and dizziness. We used Xe-CT to study cerebellar blood flow in 53 patients who ranged in age from 35 to 85 years. The patients were divided into two groups. One of them was the vertigo group that comprised 28 patients with rotatory sensation, and the other, the non-vertigo group of 25 patients with a sensation other than rotation. At the stage of severe symptoms, there was decreased cerebellar blood flow in all patients of both, the vertigo and the non-vertigo groups, and a decrease in the bilateral cerebellar hemisphere was observed in five patients and in a unilateral hemisphere in three patients of the vertigo group. By comparison, in the non-vertigo group, unilateral decrease of cerebellar blood flow was observed in only one patient, and a bilateral decrease in five. At the stage of severe symptoms, the mean regional cerebellar blood flow was 40.5{+-}8.0 ml/100 g/min (n=16 sides) in the vertigo group and 45.3{+-}9.5 ml/100 g/min (n=12 sides) in the non-vertigo group. At the stage of moderate symptoms, blood flow image was normal in four of 14 vertigo patients and in seven of 12 non-vertigo patients. The mean regional blood flow was 47.8{+-}8.6 ml/100 g/min (n=28 sides) in the vertigo group and 47.1{+-}5.1 ml/100 g/min (n=24 sides) in the non-vertigo group. At the asymptomatic stage, a high proportion of normal blood flow images (nine of 16 vertigo patients and 10 of 10 non-vertigo patients) was observed. The mean regional cerebellar blood flow was 51.6{+-}10.7 ml/100 g/min (n=32 sides) in the vertigo group and 52.8{+-}8.5 ml/100 g/min (n=20 sides) in the non-vertigo group. This study demonstrates that a unilateral or bilateral decrease in blood flow of the vertebrobasilar system may cause vertigo and dizziness. It also shows that Xe-CT of the cerebellum may be a valuable examination modality for the diagnosis and treatment of vertigo and dizziness. (author)

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

    Directory of Open Access Journals (Sweden)

    Joseph Richard Dusseldorp, BCom, MBBS(Hons


    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.

  13. Implications of ventricular arrhythmia "bursts" with normal epicardial flow, myocardial blush, and ST-segment recovery in anterior ST-elevation myocardial infarction reperfusion: a biosignature of direct myocellular injury "downstream of downstream". (United States)

    Majidi, Mohamed; Kosinski, Andrzej S; Al-Khatib, Sana M; Smolders, Lilian; Cristea, Ecaterina; Lansky, Alexandra J; Stone, Gregg W; Mehran, Roxana; Gibbons, Raymond J; Crijns, Harry J; Wellens, Hein J; Gorgels, Anton P; Krucoff, Mitchell W


    Establishing epicardial flow with percutaneous coronary intervention (PCI) for ST-segment elevation myocardial infarction (STEMI) is necessary but not sufficient to ensure nutritive myocardial reperfusion. We evaluated whether adding myocardial blush grade (MBG) and quantitative reperfusion ventricular arrhythmia "bursts" (VABs) surrogates provide a more informative biosignature of optimal reperfusion in patients with Thrombolysis in Myocardial Infarction (TIMI) 3 flow and ST-segment recovery (STR). Anterior STEMI patients with final TIMI 3 flow had protocol-blinded analyses of simultaneous MBG, continuous 12-lead electrocardiogram (ECG) STR, Holter VABs, and day 5-14 SPECT imaging infarct size (IS) assessments. Over 20 million cardiac cycles from >4500 h of continuous ECG monitoring in subjects with STR were obtained. IS and clinical outcomes were examined in patients stratified by MBG and VABs. VABs occurred in 51% (79/154) of subjects. Microcirculation (MBG 2/3) was restored in 75% (115/154) of subjects, of whom 53% (61/115) had VABs. No VABs were observed in subjects without microvascular flow (MBG of 0). Of 115 patients with TIMI 3 flow, STR, and MBG 2/3, those with VABs had significantly larger IS (median: 23.0% vs 6.0%, p=0.001). Multivariable analysis identified reperfusion VABs as a factor significantly associated with larger IS (p=0.015). Despite restoration of normal epicardial flow, open microcirculation, and STR, concomitant VABs are associated with larger myocardial IS, possibly reflecting myocellular injury in reperfusion settings. Combining angiographic and ECG parameters of epicardial, microvascular, and cellular response to STEMI intervention provides a more predictive "biosignature" of optimal reperfusion than do single surrogate markers. © The European Society of Cardiology 2014.

  14. The effects of hypoxemia on myocardial blood flow during exercise. (United States)

    Paridon, S M; Bricker, J T; Dreyer, W J; Reardon, M; Smith, E O; Porter, C B; Michael, L; Fisher, D J


    We evaluated the adequacy of regional and transmural blood flow during exercise and rapid pacing after 1 wk of hypoxemia. Seven mature mongrel dogs were made hypoxemic (mean O2 saturation = 72.4%) by anastomosis of left pulmonary artery to left atrial appendage. Catheters were placed in the left atrium, right atrium, pulmonary artery, and aorta. Atrial and ventricular pacing wires were placed. An aortic flow probe was placed to measure cardiac output. Ten nonshunted dogs, similarly instrumented, served as controls. Recovery time was approximately 1 wk. Cardiac output, mean aortic pressure, and oxygen saturation were measured at rest, with ventricular pacing, atrial pacing, and with treadmill exercise. Ventricular and atrial pace and exercise were at a heart rate of 200. Right ventricular free wall, left ventricular free wall, and septal blood flow were measured with radionuclide-labeled microspheres. Cardiac output, left atrial blood pressure, and aortic blood pressure were similar between the two groups of dogs in all testing states. Myocardial blood flow was significantly higher in the right and left ventricular free wall in the hypoxemic animals during resting and exercise testing states. Myocardial oxygen delivery was similar between the two groups of animals. Pacing resulted in an increase in myocardial blood flow in the control animals but not the hypoxemic animals.(ABSTRACT TRUNCATED AT 250 WORDS)

  15. Regional cerebral blood flow in focal cortical epilepsy

    DEFF Research Database (Denmark)

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


    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....... This finding accords with earlier studies. All nine patients studied in the interictal phase showed, either spontaneously or during activation by intermittent light, focal flow increases in areas presumed to comprise the epileptic focus. These interictal hyperemic foci probably reflect subictal neuronal...

  16. Cerebral blood flow tomography with xenon-133

    DEFF Research Database (Denmark)

    Lassen, N A


    and investigative purposes. This article discusses in particular its use for the selection of patients with carotid occlusion for extracranial/intracranial bypass surgery, for detection of severe arterial spasm after aneurysm bleeding, and for detection of low flow areas during severe migraine attacks. The use...

  17. Tubuloglomerular feedback dynamics and renal blood flow autoregulation in rats

    DEFF Research Database (Denmark)

    Holstein-Rathlou, N H; Wagner, A J; Marsh, D J


    To decide whether tubuloglomerular feedback (TGF) can account for renal autoregulation, we tested predictions of a TGF simulation. Broad-band and single-frequency perturbations were applied to arterial pressure; arterial blood pressure, renal blood flow and proximal tubule pressure were measured....... Data were analyzed by linear systems analysis. Broad-band forcings of arterial pressure were also applied to the model to compare experimental results with simulations. With arterial pressure as the input and tubular pressure, renal blood flow, or renal vascular resistance as outputs, the model......Hz in which, in addition, there are autonomous oscillations in TGF. Higher amplitude forcings in this band were attenuated by autoregulatory mechanisms, but low-amplitude forcings entrained the autonomous oscillations and provoked amplified oscillations in blood flow, showing an effect of TGF on whole kidney...

  18. Viscoelastic capillary flow: the case of whole blood

    Directory of Open Access Journals (Sweden)

    David Rabaud


    Full Text Available The dynamics of spontaneous capillary flow of Newtonian fluids is well-known and can be predicted by the Lucas-Washburn-Rideal (LWR law. However a wide variety of viscoelastic fluids such as alginate, xanthan and blood, does not exhibit the same Newtonian behavior.In this work we consider the Herschel-Bulkley (HB rheological model and Navier-Stokes equation to derive a generic expression that predicts the capillary flow of non-Newtonian fluids. The Herschel-Bulkley rheological model encompasses a wide variety of fluids, including the Power-law fluids (also called Ostwald fluids, the Bingham fluids and the Newtonian fluids. It will be shown that the proposed equation reduces to the Lucas-Washburn-Rideal law for Newtonian fluids and to the Weissenberg-Rabinowitsch-Mooney (WRM law for power-law fluids. Although HB model cannot reduce to Casson’s law, which is often used to model whole blood rheology, HB model can fit the whole blood rheology with the same accuracy.Our generalized expression for the capillary flow of non-Newtonian fluid was used to accurately fit capillary flow of whole blood. The capillary filling of a cylindrical microchannel by whole blood was monitored. The blood first exhibited a Newtonian behavior, then after 7 cm low shear stress and rouleaux formation made LWR fails to fit the data: the blood could not be considered as Newtonian anymore. This non-Newtonian behavior was successfully fit by the proposed equation.

  19. Age and gender related differences in aortic blood flow

    DEFF Research Database (Denmark)

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


    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 is to investi......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...... is to investigate the blood flow pat- terns within a group of healthy volunteers (4 females, 7 males) aged 23 to 76 years to identify changes and differences related to age and gender. The healthy volunteers were categorized by gender (male/female) and age (below/above 35 years). Subject-specific flow and geometry...... to elderly. Thus, changes in blood flow patterns in the AA related to age and gender is observed. Further investigations are needed to determine the relation between changes in blood flow patterns and AAA development....

  20. Intrinsic regulation of blood flow in adipose tissue

    DEFF Research Database (Denmark)

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


    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...... 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....... Following total ischemia all experiments showed a period with reactive hyperemia, and both duration of hyperemia and excess flow was related to the duration of the ischemia. This response therefore seems more resistant to the experimental procedure, while autoregulation of blood flow to lowered pressure...

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

    Directory of Open Access Journals (Sweden)

    Bengtsson Hans-Uno


    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.

  2. Hemoperfusion with polymyxin B-immobilized fiber column improves liver function after ischemia-reperfusion injury

    Institute of Scientific and Technical Information of China (English)

    Hiroaki Sato; Kiyohiro Oshima; Katsumi Kobayashi; Hodaka Yamazaki; Yujin Suto; Izumi Takeyoshi


    AIM: To investigate the usefulness of direct hemoperfusion with a polymyxin B-immobilized fiber column (DHP-PMX therapy) for warm hepatic ischemia-reperfusion (I/R) injury after total hepatic vascular exclusion (THVE) using a porcine model.METHODS: Eleven Mexican hairless pigs weighing 22-38 kg were subjected to THVE for 120 min and then observed for 360 min. The animals were divided into two groups randomly: the DHP-PMX group (n = 5) underwent DHP-PMX at a flow rate of 80 mL/min for 120 min (beginning 10 min before reperfusion), while the control group did not (n = 6). The rate pressure product (RPP): heart rate × end-systolic arterial blood pressure,hepatic tissue blood flow (HTBF), portal vein blood flow (PVBF), and serum aspartate aminotransferase (AST) levels were compared between the two groups. RESULTS: RPP and HTBF were significantly (P < 0.05) higher in the DHP-PMX group than in the control group 240 and 360 min after reperfusion. PVBF in the DHP-PMX group was maintained at about 70% of the flow before ischemia and differed significantly (P < 0.05) compared to the control group 360 min after reperfusion. The serum AST increased gradually after reperfusion in both groups, but the AST was significantly (P < 0.05) lower in the DHP-PMX group 360 min after reperfusion. CONCLUSION: DHP-PMX therapy reduced the hepatic warm I/R injury caused by THVE in a porcine model.

  3. Opposite effects of prostacyclin on hepatic blood flow and oxygen consumption after burn and sepsis. (United States)

    Tadros, Tamer; Traber, Daniel L; Herndon, David N


    Burn and sepsis are associated with hepatic ischemia and reperfusion injury. This study examines the hypothesis that postburn treatment with the vasodilator prostacyclin would be beneficial for hepatic perfusion and oxygenation. Female pigs (n = 18, 20-25 kg) underwent laparotomy, during which ultrasonic flow probes were placed on the portal vein and the common hepatic artery. Catheters were inserted in the superior mesenteric and left hepatic veins. After 5 days, all animals were anesthetized and 12 of them received 40% total body surface area third-degree burn; 100 microg/kg Escherichia coli lipopolysaccharide (LPS) was intravenously administered 18 hours postburn. Burned animals were randomized to receive a constant infusion of iloprost (20 ng/kg per minute) or an equivalent amount of carrier solution (normal saline). All animals were studied for 42 hours. Burn caused a 2.5-fold increase in hepatic arterial vascular resistance (HAVR) and a 39% decrease in hepatic arterial blood flow (HABF). Postburn administration of iloprost did not improve the hepatic arterial hemodynamics (1.8-fold increase in HAVR and 38% decrease in HABF). Post-LPS, HABF was significantly reduced to 22% of baseline and HAVR was 15-fold increased (P portal venous blood flow (PVBF, 79% of baseline vs. 45% of baseline in nontreated animals, P Portal venous pressure showed 16% and 56% increases after burn and endotoxin, respectively. Portal hypertension did not occur in iloprost-treated animals, as portal venous pressure remained within baseline range (P oxygen delivery (hDO2, 63% and 12% of baseline, respectively) and hepatic oxygen consumption (hVO2, 61% and 21% of baseline, respectively). Only during the postburn endotoxic phase, iloprost improved hDO2 and hVO2 (140% and 79%, respectively; P oxygenation. In addition, prostacyclin treatment attenuated burn- and endotoxin-induced portal hypertension.

  4. Partitioning of red blood cell aggregates in bifurcating microscale flows (United States)

    Kaliviotis, E.; Sherwood, J. M.; Balabani, S.


    Microvascular flows are often considered to be free of red blood cell aggregates, however, recent studies have demonstrated that aggregates are present throughout the microvasculature, affecting cell distribution and blood perfusion. This work reports on the spatial distribution of red blood cell aggregates in a T-shaped bifurcation on the scale of a large microvessel. Non-aggregating and aggregating human red blood cell suspensions were studied for a range of flow splits in the daughter branches of the bifurcation. Aggregate sizes were determined using image processing. The mean aggregate size was marginally increased in the daughter branches for a range of flow rates, mainly due to the lower shear conditions and the close cell and aggregate proximity therein. A counterintuitive decrease in the mean aggregate size was apparent in the lower flow rate branches. This was attributed to the existence of regions depleted by aggregates of certain sizes in the parent branch, and to the change in the exact flow split location in the T-junction with flow ratio. The findings of the present investigation may have significant implications for microvascular flows and may help explain why the effects of physiological RBC aggregation are not deleterious in terms of in vivo vascular resistance.

  5. Complex blood flow quantification using real-time in vivo vector flow ultrasound

    DEFF Research Database (Denmark)

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

    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...... patterns can be visualised and quantified with real-time in vivo vector flow. Good agreement between visual evaluation and the quantitative method has been shown. A standard deviation of vector angle estimates above 30 is proposed to define complex blood flow....

  6. Peripheral blood flow control in diabetes mellitus

    DEFF Research Database (Denmark)

    Hilsted, Jannik


    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....

  7. Amelioration of ischemia/reperfusion-induced myocardial infarction by the 2-alkynyladenosine derivative 2-octynyladenosine (YT-146). (United States)

    Sasamori, Jun; Aihara, Kazuyuki; Yoneyama, Fumiya; Sato, Isamu; Kogi, Kentaro; Takeo, Satoshi


    The present study was aimed at determining whether the novel adenosine A2-agonist YT-146 may have cardioprotective effects against ischemia-reperfusion injury. Anesthetized open-chest dogs underwent 90-min occlusion of the left anterior descending artery and subsequent 300-min reperfusion. The animals were randomly assigned to receive vehicle, 3, or 10 microg/kg YT-146 or ischemic preconditioning (4 episodes of 5 min occlusion followed by 5 min of reperfusion). Blood pressure, heart rate, and regional myocardial blood flow throughout the experiment were measured, as was the myocardial infarct size after reperfusion. The infarct size of the vehicle-treated dog was 56.2% +/- 2.7% (n = 5), whereas that of 3 or 10 microg/kg YT-146-treated dog was smaller (ie, 29.5% +/- 8.7% or 20.2% +/- 7.0%, respectively; n = 5). The infarct size of the dog treated with 10 microg/kg YT-146 was reduced to a degree similar to that of the ischemic preconditioning (19.2% +/- 6.3%, n = 5). YT-146 at both doses elicited a dose-dependent increase in acute hyperemic coronary flow immediately after reperfusion. The cardioprotective effect may be attributed to the limitation of the infarct size, probably via A2-receptor-mediated coronary artery dilatation during the early period of reperfusion.

  8. Design and Simulation of Axial Flow Maglev Blood Pump

    Directory of Open Access Journals (Sweden)

    Huachun Wu


    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. An analysis of the sluicing gate in pulmonary blood flow. (United States)

    Fung, Y C; Zhuang, F Y


    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.

  10. [The landmarks of the measurement of cerebral blood flow]. (United States)

    István, Nyáry


    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.

  11. Regional neurohypophysial and hypothalamic blood flow in rats during hypercapnia

    Energy Technology Data Exchange (ETDEWEB)

    Bryan, R.M. Jr.; Myers, C.L.; Page, R.B.


    Regional cerebral blood flow (rCBF) was measured in the neurohypophysis and hypothalamus in normocapnic and hypercapnic rats using (/sup 14/C)isopropyliodoamphetamine. Rats were surgically prepared using nitrous oxide and halothane and placed in plaster restraining casts. Hypercapnia was produced by increasing the fractional concentration of inspired CO/sub 2/ (FICO/sub 2/). rCBF in normocapnic rats was higher in the paraventricular nucleus, supraoptic nucleus, median eminence, and neural lobe than rates previously measured by use of diffusible tracers. During hypercapnia blood flow increased linearly with arterial PCO/sub 2/ (PACO/sub 2/) in all regions except the median eminence and neural lobe, which were not affected by hypercapnia. When rats were pretreated with phentolamine (1 mg/kg) to block the alpha-adrenergic receptors, blood flow in the median eminence and neural lobe increased significantly during hypercapnia. We conclude that blood flow in the cell bodies of the paraventricular nucleus and supraoptic nucleus is regulated differently during hypercapnia than blood flow in the nerve terminals in the median eminence and neural lobe. Furthermore, vasodilation produced by increased CO/sub 2/ is offset by alpha-receptor stimulation in the median eminence and neural lobe.

  12. Effects of Aortic Irregularities on the Blood Flow (United States)

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


    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.

  13. 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 Jelstrup


    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...... and subcutaneous blood flow (QBF, SqBF) was assessed by Laser Doppler and 133Xe clearance. Tissue oxygen tension (TO(2)) was measured by a LICOX O(2)-electrode. Tissue glucose and lactate (Tgluc, Tlact) were assessed by microdialysis. The parameters were studied after intravenous infusion of 1.0 mg nicotine......, smoking of one cigarette, arterial occlusion, and reperfusion. RESULTS: Nicotine infusion decreased SqBF from 4.2 +/- 2.0 to 3.1 +/- 1.2 mL/100 g tissue/min (P

  14. Quantitative myocardial blood flow with Rubidium-82 PET

    DEFF Research Database (Denmark)

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


    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...

  15. 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


    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...

  16. Nonuniform blood flow in the canine left ventricle. (United States)

    Flynn, A E; Coggins, D L; Austin, R E; Muehrcke, D D; Aldea, G S; Goto, M; Doucette, J W; Hoffman, J I


    In order to investigate the relationship between coronary perfusion pressure and blood flow distribution in the left ventricle (LV), we measured myocardial blood flow in small regions using radioactive microspheres in six anesthetized, open-chest dogs. Mean coronary perfusion pressure (CPP) was controlled with a femoral artery to left main coronary artery shunt which included a pressurized, servo-controlled blood reservoir. In each dog, we measured flow in 192 regions of the LV free wall (mean weight per region = 206 +/- 38 mg) at different perfusion pressures. At CPP = 80 mm Hg, blood flow to individual regions varied fourfold (0.30 to 1.18 ml/min/g; relative dispersion (RD) = 21.8 +/- 2.3%). At CPP = 50 mm Hg, flow varied over sevenfold (0.08 to 0.60 ml/min/g; RD = 42.8 +/- 10%; P less than 0.01 vs 80 mm Hg). This relationship between flow variability and CPP was present within individual LV layers as well between layers and is much higher than the error associated with the microsphere technique. We conclude that blood flow to small regions of the LV is markedly nonuniform. This heterogeneity becomes more profound at lower CPP. These findings suggest that (1) global measurements of coronary flow must be interpreted with caution, and (2) even in hearts with normal coronary arteries some regions of the LV are more susceptible to ischemia than others. In addition, these findings may help explain the patchy nature of myocardial damage that occurs following periods of low coronary pressure or inadequate myocardial protection during cardiopulmonary bypass.

  17. Oxygen-glucose deprivation and reoxygenation as an in vitro ischemia-reperfusion injury model for studying blood-brain barrier dysfunction. (United States)

    Alluri, Himakarnika; Anasooya Shaji, Chinchusha; Davis, Matthew L; Tharakan, Binu


    Ischemia-Reperfusion (IR) injury is known to contribute significantly to the morbidity and mortality associated with ischemic strokes. Ischemic cerebrovascular accidents account for 80% of all strokes. A common cause of IR injury is the rapid inflow of fluids following an acute/chronic occlusion of blood, nutrients, oxygen to the tissue triggering the formation of free radicals. Ischemic stroke is followed by blood-brain barrier (BBB) dysfunction and vasogenic brain edema. Structurally, tight junctions (TJs) between the endothelial cells play an important role in maintaining the integrity of the blood-brain barrier (BBB). IR injury is an early secondary injury leading to a non-specific, inflammatory response. Oxidative and metabolic stress following inflammation triggers secondary brain damage including BBB permeability and disruption of tight junction (TJ) integrity. Our protocol presents an in vitro example of oxygen-glucose deprivation and reoxygenation (OGD-R) on rat brain endothelial cell TJ integrity and stress fiber formation. Currently, several experimental in vivo models are used to study the effects of IR injury; however they have several limitations, such as the technical challenges in performing surgeries, gene dependent molecular influences and difficulty in studying mechanistic relationships. However, in vitro models may aid in overcoming many of those limitations. The presented protocol can be used to study the various molecular mechanisms and mechanistic relationships to provide potential therapeutic strategies. However, the results of in vitro studies may differ from standard in vivo studies and should be interpreted with caution.

  18. Maximum Likelihood Blood Velocity Estimator Incorporating Properties of Flow Physics

    DEFF Research Database (Denmark)

    Schlaikjer, Malene; Jensen, Jørgen Arendt


    The aspect of correlation among the blood velocities in time and space has not received much attention in previous blood velocity estimators. The theory of fluid mechanics predicts this property of the blood flow. Additionally, most estimators based on a cross-correlation analysis are limited...... of simulated and in vivo data from the carotid artery. The estimator is meant for two-dimensional (2-D) color flow imaging. The resulting mathematical relation for the estimator consists of two terms. The first term performs a cross-correlation analysis on the signal segment in the radio frequency (RF......)-data under investigation. The flow physic properties are exploited in the second term, as the range of velocity values investigated in the cross-correlation analysis are compared to the velocity estimates in the temporal and spatial neighborhood of the signal segment under investigation. The new estimator...

  19. Mediators of increased blood flow in porcine skin

    Directory of Open Access Journals (Sweden)

    H. D. Moore


    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.

  20. Intraoperative multi-exposure speckle imaging of cerebral blood flow. (United States)

    Richards, Lisa M; Kazmi, Sm Shams; Olin, Katherine E; Waldron, James S; Fox, Douglas J; Dunn, Andrew K


    Multiple studies have demonstrated that laser speckle contrast imaging (LSCI) has high potential to be a valuable cerebral blood flow monitoring technique during neurosurgery. However, the quantitative accuracy and sensitivity of LSCI is limited, and highly dependent on the exposure time. An extension to LSCI called multi-exposure speckle imaging (MESI) overcomes these limitations, and was evaluated intraoperatively in patients undergoing brain tumor resection. This clinical study ( n = 8) recorded multiple exposure times from the same cortical tissue area spanning 0.5-20 ms, and evaluated images individually as single-exposure LSCI and jointly using the MESI model. This study demonstrated that the MESI estimates provided the broadest flow sensitivity for sampling the flow magnitude in the human brain, closely followed by the shorter exposure times. Conservation of flow analysis on vascular bifurcations was used to validate physiological accuracy, with highly conserved flow estimates (blood flow changes after tissue cautery. Results from this study demonstrate that intraoperative MESI can be performed with high quantitative accuracy and sensitivity for cerebral blood flow monitoring.

  1. Flow of Red Blood Cells in Stenosed Microvessels (United States)

    Vahidkhah, Koohyar; Balogh, Peter; Bagchi, Prosenjit


    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.

  2. Coronary blood flow during cardiopulmonary resuscitation in swine

    Energy Technology Data Exchange (ETDEWEB)

    Bellamy, R.F.; DeGuzman, L.R.; Pedersen, D.C.


    Recent papers have raised doubt as to the magnitude of coronary blood flow during closed-chest cardiopulmonary resuscitation. We will describe experiments that concern the methods of coronary flow measurement during cardiopulmonary resuscitation. Nine anesthetized swine were instrumented to allow simultaneous measurements of coronary blood flow by both electromagnetic cuff flow probes and by the radiomicrosphere technique. Cardiac arrest was caused by electrical fibrillation and closed-chest massage was performed by a Thumper (Dixie Medical Inc., Houston). The chest was compressed transversely at a rate of 66 strokes/min. Compression occupied one-half of the massage cycle. Three different Thumper piston strokes were studied: 1.5, 2, and 2.5 inches. Mean aortic pressure and total systemic blood flow measured by the radiomicrosphere technique increased as Thumper piston stroke was lengthened (mean +/- SD): 1.5 inch stroke, 23 +/- 4 mm Hg, 525 +/- 195 ml/min; 2 inch stroke, 33 +/- 5 mm Hg, 692 +/- 202 ml/min; 2.5 inch stroke, 40 +/- 6 mm Hg, 817 +/- 321 ml/min. Both methods of coronary flow measurement (electromagnetic (EMF) and radiomicrosphere (RMS)) gave similar results in technically successful preparations (data expressed as percent prearrest flow mean +/- 1 SD): 1.5 inch stroke, EMF 12 +/- 5%, RMS 16 +/- 5%; 2 inch stroke, EMF 30 +/- 6%, RMS 26 +/- 11%; 2.5 inch stroke, EMF 50 +/- 12%, RMS 40 +/- 20%. The phasic coronary flow signal during closed-chest compression indicated that all perfusion occurred during the relaxation phase of the massage cycle. We concluded that coronary blood flow is demonstrable during closed-chest massage, but that the magnitude is unlikely to be more than a fraction of normal.

  3. Diabetes augments in vivo microvascular blood flow dynamics after stroke. (United States)

    Tennant, Kelly A; Brown, Craig E


    Stroke usually affects people with underlying medical conditions. In particular, diabetics are significantly more likely to have a stroke and the prognosis for recovery is poor. Because diabetes is associated with degenerative changes in the vasculature of many organs, we sought to determine how hyperglycemia affects blood flow dynamics after an ischemic stroke. Longitudinal in vivo two-photon imaging was used to track microvessels before and after photothrombotic stroke in a diabetic mouse model. Chronic hyperglycemia exacerbated acute (3-7 d) ischemia-induced increases in blood flow velocity, vessel lumen diameter, and red blood cell flux in peri-infarct regions. These changes in blood flow dynamics were most evident in superficial blood vessels within 500 μm from the infarct, rather than deeper or more distant cortical regions. Long-term imaging of diabetic mice not subjected to stroke indicated that these acute stroke-related changes in vascular function could not be attributed to complications from hyperglycemia alone. Treating diabetic mice with insulin immediately after stroke resulted in less severe alterations in blood flow within the first 7 d of recovery, but had more variable results at later time points. Analysis of microvessel branching patterns revealed that stroke led to a pruning of microvessels in peri-infarct cortex, with very few instances of sprouting. These results indicate that chronic hyperglycemia significantly affects the vascular response to ischemic stroke and that insulin only partially mitigates these changes. The combination of these acute and chronic alterations in blood flow dynamics could underlie diabetes-related deficits in cortical plasticity and stroke recovery.

  4. Fontan Outcomes and Pulmonary Blood Flow at Birth. (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


    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.

  5. Adrenergic influence on gastric mucosal blood flow in gastric fistula dogs

    DEFF Research Database (Denmark)

    Hovendal, C P; Bech, K; Gottrup, F;


    by an initial increase in mucosal blood flow and in the last two periods a decrease in blood flow. alpha-Blockade (phentolamine) reduced the pentagastrin stimulated gastric acid secretion and gastric mucosal blood flow but the ratio between blood flow and acid secretion was increased, indicating a relatively...

  6. Reperfusion of specific cortical areas is associated with improvement in distinct forms of hemispatial neglect. (United States)

    Khurshid, Shaan; Trupe, Lydia A; Newhart, Melissa; Davis, Cameron; Molitoris, John J; Medina, Jared; Leigh, Richard; Hillis, Argye E


    To test the hypothesis that restoring blood flow to specific right cortical regions in acute stroke results in improvement in distinct forms of hemispatial neglect distinguished by reference frame: viewer-centered versus stimulus-centered neglect. Twenty five patients with acute right stroke were evaluated at Day 1 and Day 3-5 with a battery of neglect tests and Diffusion- and Perfusion-Weighted MR Imaging. Multivariate linear regression analysis revealed Brodmann areas (BAs) where reperfusion predicted degree of improvement in scores on each type of neglect, independently of reperfusion of other areas, total change in the volume of infarct or hypoperfusion, and age. Reperfusion of dorsal frontoparietal cortex (including BAs 40, 46, and 4) independently predicted improvement in viewer-centered neglect, such as detecting stimuli on left in line cancellation and scene copying (r=.951; p<.0001). Reperfusion of a more ventral temporo-occipital cortex, including right BAs 37, 38, 21 and 18, independently contributed to improvement in stimulus-centered neglect, such as detecting left gaps in circles (r=.926; p<.0001). Reperfusion of right midfusiform gyrus (temporal occipital cortex), change in total volume of ischemia, change in volume of hypoperfusion and age predicted degree of improvement in reading (reduction in "neglect dyslexic" errors; r=.915; p<.0001). Results demonstrate that reperfusing specific cortical regions yields improvement in different types of neglect. Copyright © 2011 Elsevier Srl. All rights reserved.

  7. High speed optical holography of retinal blood flow

    CERN Document Server

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


    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.

  8. Cerebral blood flow and oxidative metabolism during human endotoxemia

    DEFF Research Database (Denmark)

    Møller, Kirsten; Strauss, Gitte Irene; Qvist, Jesper;


    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 catecholamines was investigated in eight healthy young volunteers. Cerebral blood flow was measured by the Kety-Schmidt technique at baseline (during normocapnia and voluntary hyperventilation for calculation of subject-specific cerebrovascular CO reactivity), and 90 minutes after an intravenous bolus...

  9. Disparity in regional cerebral blood flow during electrically induced seizure

    DEFF Research Database (Denmark)

    Sestoft, D; Meden, P; Hemmingsen, R


    This is a presentation of 2 cases in which the intraictal regional cerebral blood flow distribution was measured with the 99mTc-HMPAO single photon emission computerized tomography technique during an electrically induced seizure. Although the seizure was verified as generalized on electroencepha......This is a presentation of 2 cases in which the intraictal regional cerebral blood flow distribution was measured with the 99mTc-HMPAO single photon emission computerized tomography technique during an electrically induced seizure. Although the seizure was verified as generalized...... electroencephalography-verified generalized seizures....

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

    DEFF Research Database (Denmark)

    Nyberg, Michael Permin; Hellsten, Ylva


    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...... and the ability for functional sympatholysis; an attenuation of the vasoconstrictor effect of sympathetic nervous activity. These vascular adaptations with physical activity are likely to be an effect of improved nitric oxide and ATP signaling. Collectively, precise matching of blood flow and O2 delivery to meet...

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

    DEFF Research Database (Denmark)

    Bergeron, R; Kjaer, M; Simonsen, L


    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......-blockade group vs. the control group, hormones, metabolites, VO(2), and RER followed the same pattern of changes in ACE-blockade and control groups during exercise. Splanchnic blood flow (at rest: 1.67 +/- 0.12, ACE blockade; 1.59 +/- 0.18 l/min, control) decreased during moderate exercise (0.78 +/- 0.07, ACE...

  12. Diosmin alleviates retinal edema by protecting the blood-retinal barrier and reducing retinal vascular permeability during ischemia/reperfusion injury.

    Directory of Open Access Journals (Sweden)

    Nianting Tong

    Full Text Available BACKGROUND AND PURPOSE: Retinal swelling, leading to irreversible visual impairment, is an important early complication in retinal ischemia/reperfusion (I/R injury. Diosmin, a naturally occurring flavonoid glycoside, has been shown to have antioxidative and anti-inflammatory effects against I/R injury. The present study was performed to evaluate the retinal microvascular protective effect of diosmin in a model of I/R injury. METHODS: Unilateral retinal I/R was induced by increasing intraocular pressure to 110 mm Hg for 60 min followed by reperfusion. Diosmin (100 mg/kg or vehicle solution was administered intragastrically 30 min before the onset of ischemia and then daily after I/R injury until the animals were sacrificed. Rats were evaluated for retinal functional injury by electroretinogram (ERG just before sacrifice. Retinas were harvested for HE staining, immunohistochemistry assay, ELISA, and western blotting analysis. Evans blue (EB extravasation was determined to assess blood-retinal barrier (BRB disruption and the structure of tight junctions (TJ was examined by transmission electron microscopy. RESULTS: Diosmin significantly ameliorated the reduction of b-wave, a-wave, and b/a ratio in ERG, alleviated retinal edema, protected the TJ structure, and reduced EB extravasation. All of these effects of diosmin were associated with increased zonular occluden-1 (ZO-1 and occludin protein expression and decreased VEGF/PEDF ratio. CONCLUSIONS: Maintenance of TJ integrity and reduced permeability of capillaries as well as improvements in retinal edema were observed with diosmin treatment, which may contribute to preservation of retinal function. This protective effect of diosmin may be at least partly attributed to its ability to regulate the VEGF/PEDF ratio.


    Institute of Scientific and Technical Information of China (English)

    申国明; 徐颖; 何峰; 许冠荪


    Objective: To investigate the relationship between electroacupuncture (EA)-induced improvement of regional cerebral blood flow and the alternations of vasoactive intestinal peptide (VIP) and endothelin (ET) in rats with experimental vascular dementia (VD).Methods: 40 Wistar rats were evenly randomized into sham-operation, model, medication (Nimotone) and EA groups.Vascular dementia model was established by repeated cerebral ischemia-reperfusion which was induced by occlusion and reopen of the bilateral common carotid arteries.EA (2~200 Hz, 2~3 mA) was applied to "Baihui"(GV 20), "Dazhui"(GV 14) and "Zusanli"(ST 36) for 30 min, once daily and continuously for 15 days.The regional cerebral blood flow (rCBF) in parietal lobe and hippocampus was determined with method of hydrogen clearance; a step-down avoidance test was adopted to observe the rats' behavior change; and plasma VIP and ET contents were assayed by radioimmunoassay.Results: In comparison with sham-operation group, the correct rate of step-down avoidance test, rCBF in parietal lobe and hippocampus and plasma VIP level in VD model group lowered significantly (P<0.01) and plasma ET increased considerably (P<0.01).However, compared with model group, the correct rate of step-down avoidance test, rCBF values and plasma VIP in EA group raised obviously while plasma ET declined significantly.No significant differences were found between EA and medication groups in the 4 indexes.Conclusion: EA can raise rCBF in the parietal lobe and hippocampus, elevate plasma VIP level and reduce plasma ET in rats with VD.

  14. Improved technique for blood flow velocity measurement using Doppler effect (United States)

    Valadares Oliveira, Eduardo J.; Nantes Button, Vera L. d. S.; Maia, Joaquim M.; Costa, Eduardo T.


    The Doppler velocimeter developed allows to determine the angle between the ultrasonic beam and the velocity vector of the flow, and to calculate the precise blood flow in a vessel. Four piezoelectric transducers constitute the Doppler velocimeter. Three of these transducers are positioned to form an equilateral triangle (base of a pyramid). When these transducers move simultaneously, backward or forward from the initial position, the emitted ultrasonic beams focalize on a position (peak of the pyramid) closer or farther from the transducers faces, according to the depth of the vessel where we intend to measure de flow. The angle between the transducers allows adjusting the height of this pyramid and the position of the focus (where the three beams meet). A forth transducer is used to determine the diameter of the vessel and monitor the position of the Doppler velocimeter relative to the vessel. Simulation results showed that with this technique is possible to accomplish precise measurement of blood flow.

  15. Accurate blood flow measurements: are artificial tracers necessary? (United States)

    Poelma, Christian; Kloosterman, Astrid; Hierck, Beerend P; Westerweel, Jerry


    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.

  16. 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.

  17. Spring-network-based model of a red blood cell for simulating mesoscopic blood flow. (United States)

    Nakamura, Masanori; Bessho, Sadao; Wada, Shigeo


    We developed a mechanical model of a red blood cell (RBC) that is capable of expressing its characteristic behaviors in shear flows. The RBC was modeled as a closed shell membrane consisting of spring networks in the framework of the energy minimum concept. The fluid forces acting on RBCs were modeled from Newton's viscosity law and the conservation of momentum. In a steady shear flow, the RBC model exhibited various behaviors, depending on the shear rate; it tumbled, tank-treaded, or both. The transition from tumbling to tank-treading occurred at a shear rate of 20 s( - 1). The simulation of an RBC in steady and unsteady parallel shear flows (Couette flows) showed that the deformation parameters of the RBC were consistent with experimental results. The RBC in Poiseuille flow migrated radially towards the central axis of the flow channel. Axial migration became faster with an increase in the viscosity of the media, qualitatively consistent with experimental results. These results demonstrate that the proposed model satisfies the essential conditions for simulating RBC behavior in blood flow. Finally, a large-scale RBC flow simulation was implemented to show the capability of the proposed model for analyzing the mesoscopic nature of blood flow.

  18. Effect of warming and flow rate conditions of blood warmers on red blood cell integrity. (United States)

    Poder, T G; Pruneau, D; Dorval, J; Thibault, L; Fisette, J-F; Bédard, S K; Jacques, A; Beauregard, P


    Fluid warmers are routinely used to reduce the risk of hypothermia and cardiac complications associated with the infusion of cold blood products. However, warming blood products could generate haemolysis. This study was undertaken to compare the impact of temperature of blood warmers on the per cent haemolysis of packed red blood cells (RBCs) heated at different flow rates as well as non-flow conditions. Infusion warmers used were calibrated at 41·5°C ± 0·5°C and 37·5°C ± 0·5°C. Cold RBC units stored at 4°C in AS-3 (n = 30), aged 30-39 days old, were divided into half units before being allocated under two different scenarios (i.e. infusion pump or syringe). Blood warmers were effective to warm cold RBCs to 37·5°C or 41·5°C when used in conjunction with an infusion pump at flow rate up to 600 ml/h. However, when the warmed blood was held in a syringe for various periods of time, such as may occur in neonatal transfusions, the final temperature was below the expected requirements with measurement as low as 33·1°C. Increasing the flow with an infusion pump increased haemolysis in RBCs from 0·2% to up to 2·1% at a flow rate of 600 ml/h regardless of the warming device used (P < 0·05). No relevant increase of haemolysis was observed using a syringe. The use of a blood warmer adjusted to 41·5°C is probably the best choice for reducing the risk of hypothermia for the patient without generating haemolysis. However, we should be cautious with the use of an infusion pump for RBC transfusion, particularly at high flow rates. © 2016 International Society of Blood Transfusion.

  19. Amino Acids That Centrally Influence Blood Pressure and Regional Blood Flow in Conscious Rats

    Directory of Open Access Journals (Sweden)

    Yumi Takemoto


    Full Text Available Functional roles of amino acids have increasingly become the focus of research. This paper summarizes amino acids that influence cardiovascular system via the brain of conscious rats. This paper firstly describes why amino acids are selected and outlines how the brain regulates blood pressure and regional blood flow. This section includes a concise history of amino acid neurotransmitters in cardiovascular research and summarizes brain areas where chemical stimulations produce blood pressure changes mainly in anesthetized animals. This is followed by comments about findings regarding several newly examined amino acids with intracisternal stimulation in conscious rats that produce changes in blood pressure. The same pressor or depressor response to central amino acid stimulations can be produced by distinct mechanisms at central and peripheral levels, which will be briefly explained. Thereafter, cardiovascular actions of some of amino acids at the mechanism level will be discussed based upon findings of pharmacological and regional blood flow measurements. Several examined amino acids in addition to the established neurotransmitter amino acids appear to differentially activate brain structures to produce changes in blood pressure and regional blood flows. They may have physiological roles in the healthy brain, but pathological roles in the brain with cerebral vascular diseases such as stroke where the blood-brain barrier is broken.

  20. Soluble epoxide hydrolase gene deletion improves blood flow and reduces infarct size after cerebral ischemia in reproductively senescent female mice

    Directory of Open Access Journals (Sweden)

    Kristen L Zuloaga


    Full Text Available Soluble epoxide hydrolase (sEH, a key enzyme in the metabolism of vasodilatory epoxyeicosatrienoic acids (EETs, is sexually dimorphic, suppressed by estrogen, and contributes to underlying sex differences in cerebral blood flow and injury after cerebral ischemia. We tested the hypothesis that sEH inhibition or gene deletion in reproductively senescent (RS female mice would increase cerebral perfusion and decrease infarct size following stroke. RS (15-18 month old and young (3-4 month old female sEH knockout (sEHKO mice and wild type (WT mice were subjected to 45 min middle cerebral artery occlusion (MCAO with laser Doppler perfusion monitoring. WT mice were treated with vehicle or a sEH inhibitor t-AUCB at the time of reperfusion and every 24hrs thereafter for 3 days. Differences in regional cerebral blood flow were measured in vivo using optical microangiography. Infarct size was measured 3 days after reperfusion. Infarct size and cerebral perfusion 24h after MCAO were not altered by age. Both sEH gene deletion and sEH inhibition increased cortical perfusion 24h after MCAO. Neither sEH gene deletion nor sEH inhibition reduced infarct size in young mice. However, sEH gene deletion, but not sEH inhibition of the hydrolase domain of the enzyme, decreased infarct size in RS mice. Results of these studies show that sEH gene deletion and sEH inhibition enhance cortical perfusion following MCAO and sEH gene deletion reduces damage after ischemia in RS female mice; however this neuroprotection in absent is young mice.

  1. Age and gender related differences in aortic blood flow (United States)

    Enevoldsen, Marie Sand; Pedersen, Mads Møller; Hemmsen, Martin Christian; Lönn, Lars; Henneberg, Kaj-Åge; Jensen, Jørgen Arendt


    The abdominal aorta (AA) is predisposed to development of abdominal aneurysms (AAA), a focal dilatation with fatal consequences if left untreated. The blood flow patterns is thought to play an important role in the development of AAA. The purpose of this work is to investigate the blood flow patterns within a group of healthy volunteers (six females, eight males) aged 23 to 76 years to identify changes and differences related to age and gender. The healthy volunteers were categorized by gender (male/female) and age (below/above 35 years). Subject-specific flow and geometry data were acquired using the research interface on a Profocus ultrasound scanner (B-K Medical, Herlev, Denmark; segmentation of 3D magnetic resonance angiography (Magnetom Trio, Siemens Healthcare, Erlangen, Germany). The largest average diameter was among the elderly males (19.7 (+/- 1.33) mm) and smallest among the young females (12.4 (+/- 0.605) mm). The highest peak systolic velocity was in the young female group (1.02 (+/- 0.336) m/s) and lowest in the elderly male group (0.836 (+/- 0.127) m/s). A geometrical change with age was observed as the AA becomes more bended with age. This also affects the blood flow velocity patterns, which are markedly different from young to elderly. Thus, changes in blood flow patterns in the AA related to age and gender are observed. Further investigations are needed to determine the relation between changes in blood flow patterns and AAA development.

  2. [Measurement of cerebral blood flow by thermal diffusion using a flow probe with a Peltier stack]. (United States)

    Yamagata, S; Kikuchi, H; Hashimoto, K; Minamikawa, J; Watanabe, Y


    In order to evaluate the blood flow by means of thermal diffusion, relationship between blood flow and parameters induced by thermal diffusion was investigated. Flow probe employed for measurement by thermal diffusion incorporated a Peltier stack which contained a small semiconductor and two L-shaped gold plates. These two plates were attached to both sides of the semiconductor by one side of each gold plate and the other side was surfaced with a tissue to be measured. Temperature gradient is created with current applied to the Peltier stack between two plates, one cooled and the other heated, and it is affected only by tissue blood flow. Two kinds of parameters of thermal diffusion were subjected to compare to blood flow. One was temperature gradient when the constant current was applied to the Peltier stack. The other was a current required to maintain a definite temperature gradient which was determined before hand. From the theoretical principle in thermodynamics, the correlations between blood flow and each of thermal diffusion parameters were defined by the following equations: (Formula: see text) where F is blood flow, delta V is voltage converted from temperature gradient, and Ci and Cv are constants. Each of phi v and phi i indicates the characteristics of each probe. Experimental study was carried out to confirm the above relationship using cortex of experimental animals. Under the general anesthesia, a cat was placed in prone position. After the craniotomy, dura mater was opened and a small flow probe, 10 mm in diameter, 5 mm in height and 5 g in weight, was placed on the cortex and blood flow was continuously evaluated by two parameters.(ABSTRACT TRUNCATED AT 250 WORDS)

  3. Mild hypoxemia during initial reperfusion alleviates the severity of secondary energy failure and protects brain in neonatal mice with hypoxic-ischemic injury. (United States)

    Niatsetskaya, Zoya V; Charlagorla, Pradeep; Matsukevich, Dzmitry A; Sosunov, Sergey A; Mayurasakorn, Korapat; Ratner, Veniamin I; Polin, Richard A; Starkov, Anatoly A; Ten, Vadim S


    Reperfusion triggers an oxidative stress. We hypothesized that mild hypoxemia in reperfusion attenuates oxidative brain injury following hypoxia-ischemia (HI). In neonatal HI-mice, the reperfusion was initiated by reoxygenation with room air (RA) followed by the exposure to 100%, 21%, 18%, 15% oxygen for 60 minutes. Systemic oxygen saturation (SaO(2)), cerebral blood flow (CBF), brain mitochondrial respiration and permeability transition pore (mPTP) opening, markers of oxidative injury, and cerebral infarcts were assessed. Compared with RA-littermates, HI-mice exposed to 18% oxygen exhibited significantly decreased infarct volume, oxidative injury in the brain mitochondria and tissue. This was coupled with improved mitochondrial tolerance to mPTP opening. Oxygen saturation maintained during reperfusion at 85% to 95% was associated (r=0.57) with the best neurologic outcome. Exposure to 100% or 15% oxygen significantly exacerbated brain injury and oxidative stress. Compared with RA-mice, hyperoxia dramatically increased reperfusion CBF, but exposure to 15% oxygen significantly reduced CBF to values observed during the HI-insult. Mild hypoxemia during initial reperfusion alleviates the severity of HI-brain injury by limiting the reperfusion-driven oxidative stress to the mitochondria and mPTP opening. This suggests that at the initial stage of reperfusion, a slightly decreased systemic oxygenation (SaO(2) 85% to 95%) may be beneficial for infants with birth asphyxia.

  4. Protective Effects of Hydrocortisone, Vitamin C and E Alone or in Combination against Renal Ischemia-Reperfusion Injury in Rat (United States)

    Azari, Omid; Kheirandish, Reza; Azizi, Shahrzad; Farajli Abbasi, Mohammad; Ghahramani Gareh Chaman, Shahin; Bidi, Masoud


    Background: Renal ischemia reperfusion injury may occur in a variety of clinical situations, following a transient drop in total or regional blood flow to the kidney. This study was performed to investigate the protective effects of different antioxidants such as vitamin C, vitamin E, hydrocortisone and combination of these agents against experimental renal ischemia-reperfusion injury. Method: Thirty male rats were divided into six groups. Group Sham, Group I/R: (45 min of ischemia followed by 1h of reperfusion), Group I/R+Vit C: (50 mg/kg Vit C, IV, immediately after reperfusion), Group I/R+Vit E: (20 mg/kg Vit E, IM, 15 min before reperfusion), Group I/R+Hydrocortisone: (50 mg/kg, IV, immediately after reperfusion), and Group Combination: Ischemia-reperfusion plus combination of Vit C, E and hydrocortisone. After the experiments, the left kidney was removed and the tissues were processed for histopathological examination. Result: Severe injuries such as necrosis of tubules, atrophy of glomerulus, and hemorrhage were observed in group I/R. Histological scores indicating tissue injury significantly decreased in all treatment groups compared to the group I/R. The renal tissue in group treatment was preserved in comparison with the group I/R. Comparison between the treatment groups showed that group combination was more effective and group vit E was less effective in protecting of renal tissue against I/R injuries. Conclusion: The results demonstrated simultaneous administration of combination of Vit C, E and hydrocortisone before reperfusion of blood flow to the ischemic tissue could show a synergy against deleterious effects of I/R injuries in kidney. PMID:26351497

  5. Development of a miniature intraventricular axial flow blood pump. (United States)

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


    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. Vasodilator interactions in skeletal muscle blood flow regulation

    DEFF Research Database (Denmark)

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


    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...


    DEFF Research Database (Denmark)

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


    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...

  8. A New Technology for Detecting Cerebral Blood Flow

    DEFF Research Database (Denmark)

    Schytz, Henrik W; Guo, Song; Jensen, Lars T


    There is a need for real-time non-invasive, continuous monitoring of cerebral blood flow (CBF) during surgery, in intensive care units and clinical research. We investigated a new non-invasive hybrid technology employing ultrasound tagged near infrared spectroscopy (UT-NIRS) that may estimate...

  9. Cerebral blood flow response to propranolol in streptozotocin diabetic rats

    DEFF Research Database (Denmark)

    Lass, Preben; Knudsen, G M


    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...

  10. 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...

  11. Patterns of regional cerebral blood flow in acute stroke

    DEFF Research Database (Denmark)

    Olsen, T S; Skriver, E B


    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...

  12. Longitudinal Cerebral Blood Flow Changes during Speech in Hereditary Ataxia (United States)

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


    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…

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

    NARCIS (Netherlands)

    Zeeman, GG; Hatab, MR; Twickler, DM


    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

  14. Abnormal blood flow in the sublingual microcirculation at high altitude

    NARCIS (Netherlands)

    Martin, D.S.; Ince, C.; Goedhart, P.; Levett, D.Z.H.; Grocott, M.P.W.


    We report the first direct observations of deranged microcirculatory blood flow at high altitude, using sidestream dark-field imaging. Images of the sublingual microcirculation were obtained from a group of 12 volunteers during a climbing expedition to Cho Oyu (8,201 m) in the Himalayas.

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

    DEFF Research Database (Denmark)

    Boushel, Robert Christopher


    During muscle contraction, several mechanisms regulate blood flow to ensure a close coupling between muscle oxygen delivery and metabolic demand. No single factor has been identified to constitute the primary metabolic regulator, yet there are signal transduction pathways between skeletal muscle...

  16. Disparity in regional cerebral blood flow during electrically induced seizure

    DEFF Research Database (Denmark)

    Sestoft, D; Meden, P; Hemmingsen, R


    This is a presentation of 2 cases in which the intraictal regional cerebral blood flow distribution was measured with the 99mTc-HMPAO single photon emission computerized tomography technique during an electrically induced seizure. Although the seizure was verified as generalized on electroencepha...

  17. Renal blood flow in experimental septic acute renal failure

    NARCIS (Netherlands)

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


    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

  18. Nocturnal foot blood flow in patients with arterial insufficiency

    DEFF Research Database (Denmark)

    Jelnes, Rolf; Tønnesen, K H


    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...

  19. Longitudinal Cerebral Blood Flow Changes during Speech in Hereditary Ataxia (United States)

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


    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…

  20. [Measurement of cerebral blood flow using phase-contrast MRI]. (United States)

    Obata, T; Shishido, F; Koga, M; Ikehira, H; Kimura, F; Yoshida, K


    The development of phase-contrast magnetic resonance imaging(P-C MRI) provides a noninvasive method for measurement of volumetric blood flow(VFR). The VFR of the left and right internal carotid arteries and basilar artery were measured using P-C MRI, and total cerebral blood flow(tCBF) was calculated by summing up the VFR values in three vessels. We investigated the changes in these blood flows as influenced from age, head size, height, weight, body surface area and handedness. Moreover, regional CBF(rCBF) was measured by combining with the single photon emission computed tomography(SPECT) of 123I. The blood flows were 142 +/- 58 mL/ min(mean +/- SD) in the basilar artery, 229 +/- 86 mL/min in the left, 223 +/- 58 mL/min in the right internal carotid artery, and tCBF was 617 +/- 128 mL/min(Ref. Magn Resn Imaging 14:P. 1143, 1996). Significant increases were observed in head-size-related change of VFR in the basilar artery and height-related change of tCBF. The value of rCBF was easily acquired in combination with SPECT. Phase-contrast MRI is useful for a noninvasive and rapid analysis of cerebral VFR and has potential for clinical use.


    Institute of Scientific and Technical Information of China (English)

    He Ji-huan


    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.

  2. Coded ultrasound for blood flow estimation using subband processing

    DEFF Research Database (Denmark)

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


    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. Optically measured microvascular blood flow contrast of malignant breast tumors.

    Directory of Open Access Journals (Sweden)

    Regine Choe

    Full Text Available Microvascular blood flow contrast is an important hemodynamic and metabolic parameter with potential to enhance in vivo breast cancer detection and therapy monitoring. Here we report on non-invasive line-scan measurements of malignant breast tumors with a hand-held optical probe in the remission geometry. The probe employs diffuse correlation spectroscopy (DCS, a near-infrared optical method that quantifies deep tissue microvascular blood flow. Tumor-to-normal perfusion ratios are derived from thirty-two human subjects. Mean (95% confidence interval tumor-to-normal ratio using surrounding normal tissue was 2.25 (1.92-2.63; tumor-to-normal ratio using normal tissues at the corresponding tumor location in the contralateral breast was 2.27 (1.94-2.66, and using normal tissue in the contralateral breast was 2.27 (1.90-2.70. Thus, the mean tumor-to-normal ratios were significantly different from unity irrespective of the normal tissue chosen, implying that tumors have significantly higher blood flow than normal tissues. Therefore, the study demonstrates existence of breast cancer contrast in blood flow measured by DCS. The new, optically accessible cancer contrast holds potential for cancer detection and therapy monitoring applications, and it is likely to be especially useful when combined with diffuse optical spectroscopy/tomography.

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

    NARCIS (Netherlands)

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


    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

  5. Whole-body vibration dosage alters leg blood flow

    NARCIS (Netherlands)

    Lythgo, Noel; Eser, Prisca; de Groot, Patricia; Galea, Mary

    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

  6. Brain energy metabolism and blood flow differences in healthy aging

    DEFF Research Database (Denmark)

    Aanerud, Joel; Borghammer, Per; Chakravarty, M Mallar


    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...

  7. How effective are alprostadil and hydrocortisone on reperfusion injury in kidney after distant organ ischemia?

    Directory of Open Access Journals (Sweden)

    Ali Ebrahimi


    Full Text Available Background: After reestablishment of blood flow to ischemic limb recirculation of free radicals may cause ischemia-reperfusion injury in many organs. This study designed to investigate effects of hydrocortisone and alprostadil distant injury to kidneys by both measuring biochemical markers of oxidative stress and histopathologic examination in an experimental rat model of hind limb ischemia-reperfusion. Materials and Methods: This study conducted in Isfahan University of Medical Sciences during 2011-2012. Ischemia was established by infra renal aortic clamping for 60 min in 32 male Wistar rats. Animals were divided into those receiving alprostadil (group ischemia-reperfusion plus alprostadil (IR/A, n = 8, those receiving hydrocortisone (group ischemia-reperfusion plus hydrocortisone (IR/H, n = 8, control group (group ischemia-reperfusion (IR, n = 8, and sham group (n = 8. After 120 min of reperfusion both kidneys were removed. Levels of superoxide dismutase (SOD, malondialdehyde (MDA, and glutathione (GSH as indirect markers of oxidative injury was measured. Finally all data in different groups were compared using the analysis of variance (ANOVA test by Statistical Package for Social Sciences (SPSS version 16. Results: Administration of alprostadil or hydrocortisone does not improve the biochemical parameters of oxidative injury including MDA and SOD. However, statistically significant difference was seen in GSH level among sham and IR groups. Mean (΁ standard deviation (SD concentration of GSH in IR, IR/A, IR/H, and sham groups were 1028.77 (72.65, 924.82 (70.66, 1000.28 (108.77, and 846.69 (163.52, respectively (P = 0.015. Histopathological study of specimens did not show any significant changes between groups. Conclusion: Alprostadil and hydrocortisone do not improve the kidney GSH, SOD, and MDA level and kidney releases its GSH reserve during ischemia-reperfusion event, and another point is that, 3 h of ischemia-reperfusion does not develop

  8. Ultrasonic Doppler blood flow meter for extracorporeal circulation (United States)

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


    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.

  9. Noninvasive pulsatile flow estimation for an implantable rotary blood pump. (United States)

    Karantonis, Dean M; Cloherty, Shaun L; Mason, David G; Ayre, Peter J; Lovell, Nigel H


    A noninvasive approach to the task of pulsatile flow estimation in an implantable rotary blood pump (iRBP) has been proposed. Employing six fluid solutions representing a range of viscosities equivalent to 20-50% blood hematocrit (HCT), pulsatile flow data was acquired from an in vitro mock circulatory loop. The entire operating range of the pump was examined, including flows from -2 to 12 L/min. Taking the pump feedback signals of speed and power, together with the HCT level, as input parameters, several flow estimate models were developed via system identification methods. Three autoregressive with exogenous input (ARX) model structures were evaluated: structures I and II used the input parameters directly; structure II incorporated additional terms for HCT; and the third structure employed as input a non-pulsatile flow estimate equation. Optimal model orders were determined, and the associated models yielded minimum mean flow errors of 5.49% and 0.258 L/min for structure II, and 5.77% and 0.270 L/min for structure III, when validated on unseen data. The models developed in this study present a practical method of accurately estimating iRBP flow in a pulsatile environment.

  10. Quantitating error in blood flow measurements with radioactive microspheres

    Energy Technology Data Exchange (ETDEWEB)

    Austin, R.E. Jr.; Hauck, W.W.; Aldea, G.S.; Flynn, A.E.; Coggins, D.L.; Hoffman, J.I.


    Accurate determination of the reproducibility of measurements using the microsphere technique is important in assessing differences in blood flow to different organs or regions within organs, as well as changes in perfusion under various experimental conditions. The sources of error of the technique are briefly reviewed. In addition, we derived a method for combining quantifiable sources of error into a single estimate that was evaluated experimentally by simultaneously injecting eight or nine sets of microspheres (each with a different radionuclide label) into four anesthetized dogs. Each nuclide was used to calculate blood flow in 145-190 myocardial regions. We compared each flow determination (using a single nuclide label) with a weighted mean for the piece (based on the remaining nuclides). The difference was defined as ''measured'' error. In all, there were a total of 5,975 flow observations. We compared measured error with theoretical estimates based on the Poisson error of radioactive disintegration and microsphere entrapment, nuclide separation error, and reference flow error. We found that combined estimates based on these sources completely accounted for measured error in the relative distribution of microspheres. In addition, our estimates of the error in measuring absolute flows (which were established using microsphere reference samples) slightly, but significantly, underestimated measured error in absolute flow.

  11. Noninvasive miniaturized mass-flow meter using a curved cannula for implantable axial flow blood pump. (United States)

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


    Blood flow should be measured to monitor conditions of patients with implantable artificial hearts continuously and noninvasively. We have developed a noninvasive miniaturized mass-flow meter using a curved cannula for an axial flow blood pump. The mass-flow meter utilized centrifugal force generated by the mass-flow rate in the curved cannula. Two strain gauges served as sensors. Based on the numerical analysis, the first gauge, attached to the curved area, measured static pressure and centrifugal force, and the second, attached to the straight area, measured static pressure for static pressure compensation. The mass-flow rate was determined by the differences in output from the two gauges. To compensate for the inertia force under the pulsatile flow, a 0.75-Hz low-pass filter was added to the electrical circuit. In the evaluation tests, numerical analysis and an actual measurement test using bovine blood were performed to evaluate the measurement performances. As a result, in the numerical analysis, the relationship between the differential pressure caused by centrifugal force and the flow rate was verified. In the actual measurement test, measurement error was less than ± 0.5 L/min, and the time delay was 0.12 s. We confirmed that the developed mass-flow meter was able to measure mass-flow rate continuously and noninvasively.

  12. Microheterogeneity of blood flow in the rat urinary bladder

    Energy Technology Data Exchange (ETDEWEB)

    Kimura, Takahiro [Kawasaki Medical School, Kurashiki, Okayama (Japan)


    The microheterogeneity of blood flow in the mucous membrane of the urinary bladder and that in the detrusor muscle in anesthetized rats (n=8) were investigated at an extremely high spatial resolution (0.1 x 0.1 mm{sup 2}) using digital radiography combined with the {sup 3}H-labeled desmethylimipramine deposition technique. The spatial pattern of flow distribution was quantified by the coefficient of variation regional flow (CV: standard deviation/mean). The results showed muscle blood flow to be lower than mucous blood flow (muscle: mucosa=2.9:5), with the distribution of the former being more heterogeneous than that of the latter (CV in muscle vs. CV in mucosa=0.33{+-}0.033 vs. 0.16{+-}0.019, p<0.001) at the capillary level. It was therefore considered that the muscle would more easily experience mechanical irritation and be more easily influenced by arterial tonus than the mucous membrane, ant it was thought that this difference reflected a difference in regional perfusion. (author)

  13. Effects of midazolam on cerebral blood flow in human volunteers

    Energy Technology Data Exchange (ETDEWEB)

    Forster, A.; Juge, O.; Morel, D.


    The effects of intravenously administered midazolam on cerebral blood flow were evaluated in eight healthy volunteers using the /sup 133/Xe inhalation technique. Six minutes after an intravenous dose of 0.15 mg/kg midazolam, the cerebral blood flow decreased significantly (P less than 0.001) from a value of 40.6 +/- 3.3 to a value of 27.0 +/- 5.0 ml . 100 g-1 . min-1. Cerebrovascular resistance (CVR) increased from 2.8 +/- 0.2 to 3.9 to 0.6 mmHg/(ml . 100 g-1 . min-1)(P less than 0.001). Mean arterial blood pressure decreased significantly (P less than 0.05) from 117 +/- 8 to 109 +/- 9 mmHg and arterial carbon dioxide tension increased from 33.9 +/- 2.3 to 38.6 +/- 3.2 mmHg (P less than 0.05). Arterial oxygen tension remained stable throughout the study, 484 +/- 95 mmHg before the administration of midazolam and 453 +/- 76 mmHg after. All the subjects slept after the injection of the drug and had anterograde amnesia of 24.5 +/- 5 min. The decrease in mean arterial blood pressure was probably not important since it remained in the physiologic range for cerebral blood flow autoregulation. The increase in arterial carbon dioxide tension observed after the midazolam injection may have partially counteracted the effect of this new benzodiazepine on cerebral blood flow. Our data suggest that midazolam might be a safe agent to use for the induction of anethesia in neurosurgical patients with intracranial hypertension.

  14. Quantitative blood flow velocity imaging using laser speckle flowmetry (United States)

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


    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.

  15. Blood flow in the cerebral venous system: modeling and simulation. (United States)

    Miraucourt, Olivia; Salmon, Stéphanie; Szopos, Marcela; Thiriet, Marc


    The development of a software platform incorporating all aspects, from medical imaging data, through three-dimensional reconstruction and suitable meshing, up to simulation of blood flow in patient-specific geometries, is a crucial challenge in biomedical engineering. In the present study, a fully three-dimensional blood flow simulation is carried out through a complete rigid macrovascular circuit, namely the intracranial venous network, instead of a reduced order simulation and partial vascular network. The biomechanical modeling step is carefully analyzed and leads to the description of the flow governed by the dimensionless Navier-Stokes equations for an incompressible viscous fluid. The equations are then numerically solved with a free finite element software using five meshes of a realistic geometry obtained from medical images to prove the feasibility of the pipeline. Some features of the intracranial venous circuit in the supine position such as asymmetric behavior in merging regions are discussed.

  16. Simulation of red blood cell aggregation in shear flow. (United States)

    Lim, B; Bascom, P A; Cobbold, R S


    A simulation model has been developed for red blood cell (RBC) aggregation in shear flow. It is based on a description of the collision rates of RBC, the probability of particles sticking together, and the breakage of aggregates by shear forces. The influence of shear rate, hematocrit, aggregate fractal dimension, and binding strength on aggregation kinetics were investigated and compared to other theoretical and experimental results. The model was used to simulate blood flow in a long large diameter tube under steady flow conditions at low Reynolds numbers. The time and spatial distribution of the state of aggregation are shown to be in qualitative agreement with previous B-mode ultrasound studies in which a central region of low echogenicity was noted. It is suggested that the model can provide a basis for interpreting prior measurements of ultrasound echogenicity and may help relate them to the local state of aggregation.


    Directory of Open Access Journals (Sweden)

    E. V. Konstantinova


    Full Text Available Myocardial infarction and ischemic stroke remain to be of the greatest medical and social importance because of their high prevalence, disability, and mortality rates. Intractable thrombotic occlusion of the respective artery leads to the formation of an ischemic lesion focus in the tissue of the heart or brain. Emergency reperfusion serves to decrease a necrotic focus, makes its formation reversible, and reduces patient death rates. The paper considers main reperfusion therapy lines: medical (with thrombolytic drugs and mechanical (with primary interventions one and their combination in treating patients with acute myocardial and cerebral ischemia. Each reperfusion procedure is discussed in view of its advantages, disadvantages, available guidelines, and possibilities of real clinical practice. Tenecteplase is assessed in terms of its efficacy, safety, and capacities for bolus administration, which allows its use at any hospital and at the pre-hospital stage. Prehospital thrombolysis permits reperfusion therapy to bring much closer to the patient and therefore aids in reducing time to reperfusion and in salvaging as much the myocardial volume as possible. The rapidest recovery of myocardial and cerebral perfusion results in a decreased necrotic area and both improved immediate and late prognosis. The results of randomized clinical trials studying the possibilities of the medical and mechanical methods to restore blood flow are analyzed in the context of evidence-based medicine. The reason why despite the available contraindications, limited efficiency, and the risk of hemorrhagic complications, thrombolytic therapy remains the method of choice for prehospital reperfusion, an alternative to primary percutaneous coronary intervention (PCI if it cannot be carried out in patients with myocardial infarction at the stated time, and the only treatment ischemic stroke treatment that has proven its efficiency and safety in clinical trials is under

  18. Intravenous Infusion of Magnesium Chloride Improves Epicenter Blood Flow during the Acute Stage of Contusive Spinal Cord Injury in Rats (United States)

    Muradov, Johongir M.


    Abstract Vasospasm, hemorrhage, and loss of microvessels at the site of contusive or compressive spinal cord injury lead to infarction and initiate secondary degeneration. Here, we used intravenous injection of endothelial-binding lectin followed by histology to show that the number of perfused microvessels at the injury site is decreased by 80–90% as early as 20 min following a moderate T9 contusion in adult female rats. Hemorrhage within the spinal cord also was maximal at 20 min, consistent with its vasoconstrictive actions in the central nervous system (CNS). Microvascular blood flow recovered to up to 50% of normal volume in the injury penumbra by 6 h, but not at the epicenter. A comparison with an endothelial cell marker suggested that many microvessels fail to be reperfused up to 48 h post-injury. The ischemia was probably caused by vasospasm of vessels penetrating the parenchyma, because repeated Doppler measurements over the spinal cord showed a doubling of total blood flow over the first 12 h. Moreover, intravenous infusion of magnesium chloride, used clinically to treat CNS vasospasm, greatly improved the number of perfused microvessels at 24 and 48 h. The magnesium treatment seemed safe as it did not increase hemorrhage, despite the improved parenchymal blood flow. However, the treatment did not reduce acute microvessel, motor neuron or oligodendrocyte loss, and when infused for 7 days did not affect functional recovery or spared epicenter white matter over a 4 week period. These data suggest that microvascular blood flow can be restored with a clinically relevant treatment following spinal cord injury. PMID:23302047

  19. Cerebral blood flow in migraine and cortical spreading depression

    Energy Technology Data Exchange (ETDEWEB)

    Lauritzen, M.


    In a series of migraine patients, carotid arteriography was carried out as part of the clinical evalution. Nine patients developed a migrainous attack with focal neurological symptoms and headache after the angiography and during the subsequent, ongoing regional cerebral blood flow rCBF study. rCBF was measured by bolus injection of Xenon/sup 133/ into the internal carotid artery and a gamma camera with 254 collimated scintillation detectors covering the lateral aspect of the hemisphere. This technique depicts rCBF mainly at the level of the superficial cortex, with no depth resolution. The resolution is 1 cm/sup 2/ providing detailed spatial information of the cortical blood flow. Other methods for measuring local blood flow in animal and man employ a radioactive, freely diffusible tracer, in combination with an autoradiographic technique for the assessment of the tissue concentration, the so-called autoradiographic methods. In the series of patients with spontaneous migraine, rCBF was estimated using an in-vivo application of the autoradiographic principle. Xenon/sup 133/ was administered by inhalation and the time course of the arterial concentration curve was assessed by a scintillation detector over the upper right lung, since the arterial curve has been found to follow the shape of the lung curve. The rCBF was studied accompanying cortical spreading depression in rat experiments to evaluate wheter this phenomenon could explain the blood flow changes in migraine. (/sup 14/C) iodoantipyrine was given as an intravenous bolus injection and the brain content of indicator was determined by tissue sample or autoradiography after 10 or 20 seconds of isotope circulation. The conditions of the autoradiographic methods are that the flow remains constant within the period of measuring, and that the region under study is homogenous with regard to flow and lambda. (EG).

  20. MR assessment of absolute myocardial blood flow and vasodilator flow reserve in patients with hypertrophic cardiomyopathy

    Energy Technology Data Exchange (ETDEWEB)

    Kawada, Nanaka; Sakuma, Hajime; Takeda, Kan; Nakagawa, Tsuyoshi; Yamakado, Tetsu; Nakano, Takeshi [Mie Univ., Tsu (Japan). School of Medicine


    Absolute coronary blood flow per myocardial mass and coronary flow reserve for the entire left ventricle were evaluated in normals and in patients with hypertrophic cardiomyopathy (HCM) by using fast cine MR imaging and fast velocity encoded cine (VENC) MR imaging. Nine healthy volunteers and 8 patients with HCM were studied with a 1.5 T imager. Breath-hold cine MR images encompassing the whole left ventricle were acquired on short axis imaging planes in order to evaluate myocardial mass. A fast VENC MR images were obtained to measure blood flow volume in the coronary sinus before and after dipyridamole administration (TR/TE=15/5 ms, FOV=28 x 22 cm, slice thickness=5 mm). Coronary flow reserve was calculated as a ratio of hyperemic to baseline coronary flow volumes. In the baseline state, coronary blood flow per myocardial mass was significantly lower in patients with HCM than in normal myocardium (0.56{+-}0.23 vs. 0.78{+-}0.27 ml/min/g, p<0.05). After dipyridamole administration, coronary blood flow per myocardial mass in patients with HCM increased substantially less than that in healthy subjects (0.99{+-}0.38 vs. 2.22{+-}0.55 ml/min/g, p<0.01), resulting in the significantly decreased coronary flow reserve ratio in HCM in comparison with that in normal myocardium (1.86{+-}0.56 vs. 3.11{+-}1.37, p<0.05). In conclusion, breath-hold velocity encoded cine MR imaging is a noninvasive technique which can provide assessments of altered coronary blood flow volume per myocardial mass and vasodilator flow reserve in patients with HCM. (author)

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

    Directory of Open Access Journals (Sweden)

    Mandić Vesna


    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

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

    Directory of Open Access Journals (Sweden)

    Jaeseong Jang


    Full Text Available 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.

  3. 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.


    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.

  4. Blood flow simulation on a role for red blood cells in platelet adhesion (United States)

    Shimizu, Kazuya; Sugiyama, Kazuyasu; Takagi, Shu


    Large-scale blood flow simulations were conducted and a role for red blood cells in platelet adhesion was discussed. The flow conditions and hematocrit values were set to the same as corresponding experiments, and the numerical results were compared with the measurements. Numerical results show the number of platelets adhered on the wall is increased with the increase in hematocrit values. The number of adhered platelets estimated from the simulation was approximately 28 (per 0.01 square millimeter per minute) for the hematocrit value of 20%. These results agree well with the experimental results qualitatively and quantitatively, which proves the validity of the present numerical model including the interaction between fluid and many elastic bodies and the modeling of platelet adhesion. Numerical simulation also reproduces the behavior of red blood cells in the blood flow and their role in platelet adhesion. Red blood cells deform to a flat shape and move towards channel center region. In contrast, platelets are pushed out and have many chances to contact with the wall. As a result, the large number of adhered platelets is observed as hematocrit values becomes high. This result indicates the presence of red blood cells plays a crucial role in platelet adhesion.

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

    Directory of Open Access Journals (Sweden)

    Bernardino Clavo


    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.

  6. Structural analysis of red blood cell aggregates under shear flow. (United States)

    Chesnutt, J K W; Marshall, J S


    A set of measures of red blood cell (RBC) aggregates are developed and applied to examine the aggregate structure under plane shear and channel flows. Some of these measures are based on averages over the set of red blood cells which are in contact with each other at a given time. Other measures are developed by first fitting an ellipse to the planar projection of the aggregate, and then examining the area and aspect ratio of the fit ellipse as well as the orientations of constituent RBCs with respect to the fit ellipse axes. The aggregate structural measures are illustrated using a new mesoscale computational model for blood cell transport, collision and adhesion. The sensitivity of this model to change in adhesive surface energy density and shear rate on the aggregate structure is examined. It is found that the mesoscale model predictions exhibit reasonable agreement with experimental and theoretical data for blood flow in plane shear and channel flows. The new structural measures are used to examine the differences between predictions of two- and three-dimensional computations of the aggregate formation, showing that two-dimensional computations retain some of the important aspects of three-dimensional computations.

  7. Laser speckle imaging of blood flow in microcirculation

    Energy Technology Data Exchange (ETDEWEB)

    Cheng Haiying; Luo Qingming; Liu Qian; Lu Qiang; Gong Hui; Zeng Shaoqun [Key Laboratory of Biomedical Photonics of Ministry of Education of China, Huazhong University of Science and Technology, Wuhan 430074 (China)


    Monitoring the spatio-temporal characteristics of microcirculation is crucial for studying the functional activities of biotissue and the mechanism of disease. However, conventional methods used to measure blood flow suffer from limited spatial resolution or the injection of exogenous substances or the need of scanning to obtain the dynamic of regional blood flow. Laser speckle imaging (LSI) technique makes up these disadvantages by obtaining the regional blood flow distribution with high spatio-temporal resolution without the need to scan. In this paper, LSI was introduced to investigate the dynamic responses of the rat mesenteric microcirculation to an incremental dose of phentolamine. The results showed that when the dose of phentolamine was less than 4 {mu}g ml{sup -1}, local application of phentolamine on the mesentery would increase the blood perfusion as the concentration increased. When the dose increased further, the improvement decreased. At a dose of 200 {mu}g ml{sup -1}, a microcirculation impediment was caused. At the same time, different responses between veinules and arterioles were manifested. These suggested that LSI is promising to be a useful contribution to drug development and testing.

  8. Narcolepsy: regional cerebral blood flow during sleep and wakefulness

    Energy Technology Data Exchange (ETDEWEB)

    Sakai, F.; Meyer, J.S.; Karacan, I.; Yamaguchi, F.; Yamamoto, M.


    Serial measurements of regional cerebral blood flow were made by the 135Xe inhalation method during the early stages of sleep and wakefulness in eight normal volunteers and 12 patients with narcolepsy. Electroencephalogram, electro-oculogram, and submental electromyogram were recorded simultaneously. In normals, mean hemispheric gray matter blood flow (Fg) during stages I and II sleep was significantly less than waking values. Maximum regional blood flow decreases during sleep occurred in the brainstem-cerebellar, right inferior temporal, and bilateral frontal regions. In patients with narcolepsy, mean hemispheric Fg while awake was 80.5 +- 13 ml per 100 gm brain per minute. During REM sleep, mean hemispheric Fg increased concurrently with large increases in brainstem-cerebellar region flow. During stages I and II sleep without REM, there were significant increases in mean hemispheric Fg and brainstem-cerebellar Fg, just the opposite of changes in normals. In narcolepsy, there appears to be a reversal of normal cerebral deactivation patterns, particularly involving the brainstem, during stages I and II sleep.

  9. Occlusion-free Blood Flow Animation with Wall Thickness Visualization. (United States)

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


    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.

  10. Axial dispersion in flowing red blood cell suspensions (United States)

    Podgorski, Thomas; Losserand, Sylvain; Coupier, Gwennou


    A key parameter in blood microcirculation is the transit time of red blood cells (RBCs) through an organ, which can influence the efficiency of gas exchange and oxygen availability. A large dispersion of this transit time is observed in vivo and is partly due to the axial dispersion in the flowing suspension. In the classic Taylor-Aris example of a solute flowing in a tube, the combination of molecular diffusion and parabolic velocity profile leads to enhanced axial dispersion. In suspensions of non-Brownian deformable bodies such as RBCs, axial dispersion is governed by a combination of shear induced migration and shear-induced diffusion arising from hydrodynamic interactions. We revisit this problem in the case of RBC pulses flowing in a microchannel and show that the axial dispersion of the pulse eventually saturates with a final extension that depends directly on RBC mechanical properties. The result is especially interesting in the dilute limit since the final pulse length depends only on the channel width, exponent of the migration law and dimensionless migration velocity. In continuous flow, the dispersion of transit times is the result of complex cell-cell and cell-wall interactions and is strongy influenced by the polydispersity of the blood sample. The authors acknowledge support from LabEx TEC21 and CNES.

  11. Methods for blood flow measurements using ultrasound contrast agents (United States)

    Fowlkes, J. Brian


    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.

  12. In vivo photoacoustic imaging of transverse blood flow using Doppler broadening of bandwidth


    Yao, Junjie; Maslov, Konstantin I.; Shi, Yunfei; Taber, Larry A.; Lihong V. Wang


    A new method is proposed to measure transverse blood flow using photoacoustic Doppler broadening of bandwidth. By measuring bovine blood flowing through a plastic tube, the linear dependence of the broadening on the flow speed was validated. The blood flow of the microvasculature in a mouse ear and a chicken embryo (stage 16) was also studied.

  13. In vivo photoacoustic imaging of transverse blood flow by using Doppler broadening of bandwidth


    Yao, Junjie; Maslov, Konstantin I.; Shi, Yunfei; Taber, Larry A.; Lihong V. Wang


    A method is proposed to measure transverse blood flow by using photoacoustic Doppler broadening of bandwidth. By measuring bovine blood flowing through a plastic tube, the linear dependence of the broadening on the flow speed was validated. The blood flow of the microvasculature in a mouse ear and a chicken embryo (stage 16) was also studied.

  14. Lattice Boltzmann Simulation of Blood Flow in Blood Vessels with the Rolling Massage

    Institute of Scientific and Technical Information of China (English)

    YI Hou-Hui; XU Shi-Xiong; QIAN Yue-Hong; FANG Hai-Ping


    @@ The rolling massage manipulation is a classic Chinese massage, which is expected to improve the circulation by pushing, pulling and kneading of the muscle. A model for the rolling massage manipulation is proposed and the lattice Boltzmann method is applied to study the blood flow in the blood vessels. The simulation results show that the blood flux is considerably modified by the rolling massage and the explicit value depends on the rolling frequency, the rolling depth, and the diameter of the vessel. The smaller the diameter of the blood vessel, the larger the enhancement of the blood flux by the rolling massage. The model, together with the simulation results,is expected to be helpful to understand the mechanism and further development of rolling massage techniques.

  15. Effect of pregnancy on regional cerebral blood flow

    Energy Technology Data Exchange (ETDEWEB)

    Nagamachi, Shigeki; Hoshi, Hiroaki; Jinnouchi, Seishi; Ohnishi, Takashi; Futami, Shigemi; Watanabe, Katsushi; Ikeda, Tomoaki; Mori, Norimasa [Miyazaki Medical Coll., Kiyotake (Japan)


    Regional cerebral blood flow (r-CBF) of 10 pregnant women were quantified by {sup 133}Xe 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. P{sub co2} concentration increased significantly after artificial abortion. Although its mechanism is unknown, our preliminary work demonstrates that r-CBF increased by pregnancy. (author).

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

    DEFF Research Database (Denmark)

    Henriksen, O


    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...... sympathetic vasoconstrictor reflexes are blocked. Blood flow has been measure by the local 133Xe-technique. The results indicate the presence of spinal as well as supraspinal sympathetic vasoconstrictor reflexes to human peripheral tissues. Especially is emphasized the presence of a local sympathetic veno...

  17. Tomographic cerebral blood flow measurement during carotid surgery

    DEFF Research Database (Denmark)

    Rathenborg, Lisbet Knudsen; Vorstrup, Sidsel; Olsen, K S


    OBJECTIVES: The aim of the study was to depict regional cerebral blood flow (rCBF) during carotid cross clamping using 99mTechnetium-hexamethylpropylene amine oxime (TcHMPAO). This tracer rapidly passes the blood-brain barrier and is retained for hours in the brain tissue. Injecting TcHMPAO during...... RESULTS: We found a significant correlation between stump pressure and enhancement of side-to-side asymmetry in rCBF due to carotid cross clamping. Pronounced variations were seen in which regions were deprived of perfusion during clamping. CONCLUSION: TcHMPAO allows tomographic assessment of CBF during...

  18. Blood Flow Imaging in Maternal and Fetal Arteries and Veins (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.

  19. Resistance exercise with different volumes: blood pressure response and forearm blood flow in the hypertensive elderly (United States)

    Brito, Aline de Freitas; de Oliveira, Caio Victor Coutinho; Brasileiro-Santos, Maria do Socorro; Santos, Amilton da Cruz


    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 resistance. PMID:25540580

  20. 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.


    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...

  1. 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)


    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.)

  2. Mitochondria: mitochondrial participation in ischemia-reperfusion injury in skeletal muscle. (United States)

    Lejay, Anne; Meyer, Alain; Schlagowski, Anna-Isabel; Charles, Anne-Laure; Singh, François; Bouitbir, Jamal; Pottecher, Julien; Chakfé, Nabil; Zoll, Joffrey; Geny, Bernard


    Irrespective of the organ involved, restoration of blood flow to ischemic tissue is vital, although reperfusion per se is deleterious. In the setting of vascular surgery, even subtle skeletal muscle ischemia contributes to remote organ injuries and perioperative and long-term morbidities. Reperfusion-induced injury is thought to participate in up to 40% of muscle damage. Recently, the pathophysiology of lower limb ischemia-reperfusion (IR) has been largely improved, acknowledging a key role for mitochondrial dysfunction mainly characterized by impaired mitochondrial oxidative capacity and premature mitochondrial permeability transition pore opening. Increased oxidative stress triggered by an imbalance between reactive oxygen species (ROS) production and clearance, and facilitated by enhanced inflammation, appears to be both followed and instigated by mitochondrial dysfunction. Mitochondria are both actors and target of IR and therapeutic strategies modulating degree of ROS production could enhance protective signals and allow for mitochondrial protection through a mitohormesis mechanism. Copyright © 2014. Published by Elsevier Ltd.

  3. Transfer function analysis for the assessment of cerebral autoregulation using spontaneous oscillations in blood pressure and cerebral blood flow

    NARCIS (Netherlands)

    Abeelen, A.S.S. van den; Beek, A.H. van; Slump, C.H.; Panerai, R.B.; Claassen, J.A.H.R.


    Cerebral autoregulation (CA) is a key mechanism to protect the brain against excessive fluctuations in blood pressure (BP) and maintain cerebral blood flow. Analyzing the relationship between spontaneous BP and cerebral blood flow velocity (CBFV) using transfer function analysis is a widely used tec

  4. Skin temperature and subcutaneous adipose blood flow in man

    DEFF Research Database (Denmark)

    Astrup, A; Bülow, J; Madsen, J


    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...... 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...

  5. Quantitative flow and velocity measurements of pulsatile blood flow with 4D-DSA (United States)

    Shaughnessy, Gabe; Hoffman, Carson; Schafer, Sebastian; Mistretta, Charles A.; Strother, Charles M.


    Time resolved 3D angiographic data from 4D DSA provides a unique environment to explore physical properties of blood flow. Utilizing the pulsatility of the contrast waveform, the Fourier components can be used to track the waveform motion through vessels. Areas of strong pulsatility are determined through the FFT power spectrum. Using this method, we find an accuracy from 4D-DSA flow measurements within 7.6% and 6.8% RMSE of ICA PCVIPR and phantom flow probe validation measurements, respectively. The availability of velocity and flow information with fast acquisition could provide a more quantitative approach to treatment planning and evaluation in interventional radiology.

  6. Unsteady magnetohydrodynamic blood flow through irregular multi-stenosed arteries. (United States)

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


    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.

  7. Measurement of limb blood flow using technetium-labelled red blood cells

    Energy Technology Data Exchange (ETDEWEB)

    Parkin, A; Robinson, P.J.; Wiggins, P.A.; Leveson, S.H.; Salter, M.C.P.; Matthews, I.F.; Ware, F.M.


    A method for measuring blood flow below the knee during reactive hyperaemia induced by 3 min of arterial occlusion has been developed. Subjects are positioned with lower limbs within the field of view of a gamma camera and pneumatic cuffs are placed below the knees to isolate the blood and induce a hyperaemic response. The remaining blood pool is labelled with /sup 99/Tcsup(m)-labelled red cells. Blood flows have been derived from the initial gradients of time-activity curves and from equilibrium blood sampling. The technique has been validated using a tissue-equivalent leg phantom and peristaltic pump. The method has been applied to a small group of patients with peripheral vascular disease and to normal controls. The mean value (+-SD) of limb perfusion for normal controls was found to be 16.4 +- 3.0 ml/100 ml/min and for patients with intermittent claudication was 5.1 +- 2.6 ml/100 ml/min. Flow measurements are found to correlate with clinical findings and with symptoms. Reproducibility (established by repeated measurements) is high. The method is well tolerated even by patients suffering from rest pain.

  8. 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.


    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.

  9. Clitoral blood flow increases following vaginal pressure stimulation. (United States)

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


    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.

  10. High speed optical holography of retinal blood flow. (United States)

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


    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.

  11. Pressure Gradient Estimation Based on Ultrasonic Blood Flow Measurement (United States)

    Nitta, Naotaka; Homma, Kazuhiro; Shiina, Tsuyoshi


    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.

  12. Chronic intestinal ischemia and splanchnic blood-flow

    DEFF Research Database (Denmark)

    Zacho, Helle Damgaard; Henriksen, Jens Henrik; Abrahamsen, Jan


    -1390), and this value increased significantly to 1787 mL/min after the meal in healthy volunteers (P ...-induced increase in SBF was equal to 282 mL/min + 5.4 mL/min × bodyweight, (P = 0.025). The SO₂U in healthy volunteers and patients was 50.7 mL/min and 48.0 mL/min, respectively, and these values increased to 77.5 mL/min and 75 mL/min postprandially, respectively. Both baseline and postprandial SO₂U were directly......AIM: To determine the splanchnic blood flow and oxygen uptake in healthy-subjects and patients and to relate the findings to body-composition. METHODS: The total splanchnic blood flow (SBF) and oxygen uptake (SO₂U) were measured in 20 healthy volunteers (10 women) and 29 patients with suspected...

  13. Subcutaneous blood flow in early male pattern baldness

    Energy Technology Data Exchange (ETDEWEB)

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


    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.

  14. Cerebral autoregulation control of blood flow in the brain

    CERN Document Server

    Payne, Stephen


    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.

  15. Efficacy, Safety and Mechanisms of Blood Flow Restricted Exercise (United States)

    Ploutz-Snyder, Lori


    This 20 minute talk will review studies in the peer-reviewed literature related to the effectiveness of blood flow restricted exercise as an exercise training program. There is controversy regarding the talk with cover the effectiveness of various exercise protocols and these differences will be compared and contrasted. Unpublished data from my laboratory at Syracuse University will be presented (see other abstract), as well as some unpublished work from the labs of Manini, Clark and Rasmussen (none are NASA funded).

  16. Ketamine anesthesia reduces intestinal ischemia/reperfusion injury in rats

    Institute of Scientific and Technical Information of China (English)

    Carlos Roddgo Cámara; Francisco Javier Guzmán; Ernesto Alexis Barrera; Andrés Jesús Cabello; Armando Garcia; Nancy Esthela Fernández; Eloy Caballero; Jesus Ancer


    AIM:To investigate the effects of ketamine anesthesia on the motility alterations and tissue injury caused by ischemia/reperfusion in rats.METHODS:Thirty maIe Wistar rats weighing 200-250 g were used.Ischemia was induced by obstructing blood flow in 25% of the total small intestinal length(ileum)with a vascular clamp for 45 min,after which either 60 min or 24 h of reperfusion was allowed.Rats were either anesthetized with pento-barbital sodium(50 mg/kg)or ketamine(100 mg/kg).Control groups received sham surgery,After 60 min of reperfusion,the intestine was examined for mor-phological alterations,and after 24 h intestinal basic electrical rhythm(BER)frequency was calculated,and intestinal transit determined in all groups.RESULTS:The intestinal mucosa in rats that were anesthetized with ketamine showed moderate alterations such as epithelial lifting,while ulceration and hemorrhage was observed in rats that received pento-barbital sodium after 60 min of reperfusion.Quantitative analysis of structural damage using the Chiu scale showed significantly Iess injury in rats that received ketamine than in rats that did not(2.35±1.14 vs 4.58 ±0.50,P<0.0001).The distance traveled by a marker,expressed as percentage of total intestinal length,in rats that received pentobarbital sodium was 20% ± 2% in comparison with 25.9% ±1.64% in rats that received ketamine(P=0.017).BER was not statistically different between groups.CONCLUSION:Our results show that ketamine anesthesia is associated with diminished intestinal iniury and abolishes the intestinal transit delay induced by ischemia/reperfusion.(C)2008 The WJG Press.All rights reserved.

  17. Ketamine anesthesia reduces intestinal ischemia/reperfusion injury in rats (United States)

    Cámara, Carlos Rodrigo; Guzmán, Francisco Javier; Barrera, Ernesto Alexis; Cabello, Andrés Jesús; Garcia, Armando; Fernández, Nancy Esthela; Caballero, Eloy; Ancer, Jesus


    AIM: To investigate the effects of ketamine anesthesia on the motility alterations and tissue injury caused by ischemia/reperfusion in rats. METHODS: Thirty male Wistar rats weighing 200-250 g were used. Ischemia was induced by obstructing blood flow in 25% of the total small intestinal length (ileum) with a vascular clamp for 45 min, after which either 60 min or 24 h of reperfusion was allowed. Rats were either anesthetized with pentobarbital sodium (50 mg/kg) or ketamine (100 mg/kg). Control groups received sham surgery. After 60 min of reperfusion, the intestine was examined for morphological alterations, and after 24 h intestinal basic electrical rhythm (BER) frequency was calculated, and intestinal transit determined in all groups. RESULTS: The intestinal mucosa in rats that were anesthetized with ketamine showed moderate alterations such as epithelial lifting, while ulceration and hemorrhage was observed in rats that received pentobarbital sodium after 60 min of reperfusion. Quantitative analysis of structural damage using the Chiu scale showed significantly less injury in rats that received ketamine than in rats that did not (2.35 ± 1.14 vs 4.58 ± 0.50, P < 0.0001). The distance traveled by a marker, expressed as percentage of total intestinal length, in rats that received pentobarbital sodium was 20% ± 2% in comparison with 25.9% ± 1.64% in rats that received ketamine (P = 0.017). BER was not statistically different between groups. CONCLUSION: Our results show that ketamine anesthesia is associated with diminished intestinal injury and abolishes the intestinal transit delay induced by ischemia/reperfusion. PMID:18777596

  18. Effect of red blood cell rigidity on tumor blood flow: increase in viscous resistance during hyperglycemia. (United States)

    Sevick, E M; Jain, R K


    Elevated glucose level and low pH have been shown to increase red blood cell (RBC) rigidity. This increased rigidity has been proposed as one factor which mediates the tumor blood flow (TBF) reduction during hyperglycemia by (a) causing RBC entrapment and hence increasing geometric resistance and (b) increasing viscous resistance to blood flow. However, due to the inability to measure these resistances in vivo in tumors directly, the relative contribution of RBC rigidity in TBF reduction has not been quantified. In the present study, blood flow resistance was measured in "tissue-isolated" mammary adenocarcinoma R3230AC perfused ex vivo with (a) normally deformable, (b) glutaraldehyde-hardened, and (c) glucose-incubated RBC suspensions. Flow resistance measured during tumor perfusion with Krebs-Henseleit buffer prior to and following perfusion with the glutaraldehyde-hardened RBC suspensions showed no significant change, suggesting constant geometric resistance and lack of RBC entrapment. Instead, our measurements indicated increased viscous resistance with loss of deformability due to glutaraldehyde and glucose incubation even though glucose incubation did not significantly alter the apparent blood viscosity measured in vitro. Thus, the TBF reduction during hyperglycemia may be due to subtle changes in RBC deformability. These results suggest the development of strategies to increase the delivery of drugs or oxygen must take into account any changes in intratumor viscous resistance. For example, the increase in the oxygen-carrying capacity of blood using RBC transfusion or fluorocarbon emulsions may be offset by the increase in viscous resistance and the corresponding reduction in TBF.

  19. 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


    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.

  20. Ocular Blood Flow Measured Noninvasively in Zero Gravity (United States)

    Ansari, Rafat R.; Manuel, Francis K.; Geiser, Martial; Moret, Fabrice; Messer, Russell K.; King, James F.; Suh, Kwang I.


    In spaceflight or a reduced-gravity environment, bodily fluids shift to the upper extremities of the body. The pressure inside the eye, or intraocular pressure, changes significantly. A significant number of astronauts report changes in visual acuity during orbital flight. To date this remains of unknown etiology. Could choroidal engorgement be the primary mechanism and a change in the curvature or shape of the cornea or lens be the secondary mechanism for this change in visual acuity? Perfused blood flow in the dense meshwork of capillaries of the choroidal tissue (see the preceding illustration) provides necessary nutrients to the outer layers of the retina (photoreceptors) to keep it healthy and maintain good vision. Unlike the vascular system, the choroid has no baroreceptors to autoregulate fluid shifts, so it can remain engorged, pushing the macula forward and causing a hyperopic (farsighted) shift of the eye. Experiments by researchers at the NASA Glenn Research Center could help answer this question and facilitate planning for long-duration missions. We are investigating the effects of zero gravity on the choroidal blood flow of volunteer subjects. This pilot project plans to determine if choroidal blood flow is autoregulated in a reduced-gravity environment.

  1. 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.


    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.

  2. Coronary blood flow in patients with cardiac syndrome X. (United States)

    Sen, Nihat; Tavil, Yusuf; Yazici, Hüseyin Uğur; Abacl, Adnan; Cengel, Atiye


    Epicardial coronary arteries are normal in patients with cardiac syndrome X. It is, however, unclear whether there is an abnormality at the level of microvascular circulation. In this study, our aim was to evaluate the epicardial coronary blood flow and myocardial perfusion in patients with cardiac syndrome X. Two hundred and three patients (mean age 53+/-10 years, 85 men) were included in the study. The diagnosis of cardiac syndrome X was made in patients who had a complaint of typical anginal chest pain and had ischemic findings on either myocardial perfusion scintigraphy or a treadmill exercise test, and whose coronary angiograms did not reveal any pathology. Fifty patients (mean age 54+/-11 years, 24 men) who had a complaint of typical anginal chest pain and had a normal myocardial perfusion test and normal coronary arteries were recruited as the control group. Epicardial coronary blood flow was evaluated with the thrombolysis in myocardial infarction frame count method and myocardial perfusion was evaluated with the myocardial blush grade method. A myocardial blush grade of 0.05). We found that the epicardial coronary blood flow, as assessed by thrombolysis in myocardial infarction frame count, and myocardial perfusion, as assessed by myocardial blush grade, were normal in patients with cardiac syndrome X.

  3. Blood flow distribution with adrenergic and histaminergic antagonists

    Energy Technology Data Exchange (ETDEWEB)

    Baker, C.H.; Davis, D.L.; Sutton, E.T.


    Superficial fibular nerve stimulation (SFNS) causes increased pre- and post-capillary resistances as well as increased capillary permeability in the dog hind paw. These responses indicate possible adrenergic and histaminergic interactions. The distribution of blood flow between capillaries and arteriovenous anastomoses (AVA) may depend on the relative effects of these neural inputs. Right hind paws of anesthetized heparinized dogs were vascularly and neurally isolated and perfused with controlled pressure. Blood flow distribution was calculated from the venous recovery of 85Sr-labeled microspheres (15 microns). The mean transit times of 131I-albumin and 85Sr-labeled microspheres were calculated. The effects of adrenergic and histaminergic antagonists with and without SFNS were determined. Phentolamine blocked the entire response to SFNS. Prazosin attenuated increases in total and AVA resistance. Yohimbine prevented increased total resistance, attenuated the AVA resistance increase, and revealed a decrease in capillary circuit resistance. Pyrilamine attenuated total resistance increase while SFNS increased capillary and AVA resistances. Metiamide had no effect on blood flow distribution with SFNS. The increase in AVA resistance with SFNS apparently resulted from a combination of alpha 1 and alpha 2 receptor stimulation but not histaminergic effects.

  4. Pulsed photoacoustic Doppler flow measurements in blood-mimicking phantoms (United States)

    Brunker, J.; Beard, P.


    The feasibility of making spatially resolved measurements of blood flow using pulsed photoacoustic Doppler techniques has been explored. Doppler time shifts were quantified via cross-correlation of pairs of photoacoustic waveforms generated within a blood-simulating phantom using pairs of laser light pulses. The photoacoustic waves were detected using a focussed or planar PZT ultrasound transducer. For each flow measurement, a series of 100 waveform pairs was collected. Previous data processing methods involved rejection of poorly correlated waveform pairs; the modal velocity value and standard deviation were then extracted from the selected distribution of velocity measurements. However, the data selection criteria used in this approach is to some extent arbitrary. A new data analysis protocol, which involves averaging the 100 cross-correlation functions and thus uses all of the measured data, has been designed in order to prevent exclusion of outliers. This more rigorous approach has proved effective for quantifying the linear motion of micron-scale absorbers imprinted on an acetate sheet moving with velocities in the range 0.14 to 1.25 ms-1. Experimental parameters, such as the time separation between the laser pulses and the transducer frequency response, were evaluated in terms of their effect on the accuracy, resolution and range of measurable velocities. The technique was subsequently applied to fluid phantoms flowing at rates less than 5 mms-1 along an optically transparent tube. Preliminary results are described for three different suspensions of phenolic resin microspheres, and also for whole blood. Velocity information was obtained even under non-optimal conditions using a low frequency transducer and a low pulse repetition frequency. The distinguishing advantage of pulsed rather than continuous-wave excitation is that spatially resolved velocity measurements can be made. This offers the prospect of mapping flow within the microcirculation and thus

  5. Quantification of blood flow and topology in developing vascular networks.

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    Astrid Kloosterman

    Full Text Available Since fluid dynamics plays a critical role in vascular remodeling, quantification of the hemodynamics is crucial to gain more insight into this complex process. Better understanding of vascular development can improve prediction of the process, and may eventually even be used to influence the vascular structure. In this study, a methodology to quantify hemodynamics and network structure of developing vascular networks is described. The hemodynamic parameters and topology are derived from detailed local blood flow velocities, obtained by in vivo micro-PIV measurements. The use of such detailed flow measurements is shown to be essential, as blood vessels with a similar diameter can have a large variation in flow rate. Measurements are performed in the yolk sacs of seven chicken embryos at two developmental stages between HH 13+ and 17+. A large range of flow velocities (1 µm/s to 1 mm/s is measured in blood vessels with diameters in the range of 25-500 µm. The quality of the data sets is investigated by verifying the flow balances in the branching points. This shows that the quality of the data sets of the seven embryos is comparable for all stages observed, and the data is suitable for further analysis with known accuracy. When comparing two subsequently characterized networks of the same embryo, vascular remodeling is observed in all seven networks. However, the character of remodeling in the seven embryos differs and can be non-intuitive, which confirms the necessity of quantification. To illustrate the potential of the data, we present a preliminary quantitative study of key network topology parameters and we compare these with theoretical design rules.

  6. Relationship between cardiac function and resting cerebral blood flow

    DEFF Research Database (Denmark)

    Henriksen, Otto M; Jensen, Lars T; Krabbe, Katja;


    Although both impaired cardiac function and reduced cerebral blood flow are associated with ageing, current knowledge of the influence of cardiac function on resting cerebral blood flow (CBF) is limited. The aim of this study was to investigate the potential effects of cardiac function on CBF. CBF...... and cardiac output were measured in 31 healthy subjects 50-75 years old using magnetic resonance imaging techniques. Mean values of CBF, cardiac output and cardiac index were 43.6 ml per 100 g min(-1), 5.5 l min(-1) and 2.7 l min(-1) m(-2), respectively, in males, and 53.4 ml per 100 g min(-1), 4.3 l min(-1......) and 2.4 l min(-1) m(-2), respectively, in females. No effects of cardiac output or cardiac index on CBF or structural signs of brain ageing were observed. However, fractional brain flow defined as the ratio of total brain flow to cardiac output was inversely correlated with cardiac index (r(2) = 0.22, P...

  7. Rotating permanent magnet excitation for blood flow measurement. (United States)

    Nair, Sarath S; Vinodkumar, V; Sreedevi, V; Nagesh, D S


    A compact, portable and improved blood flow measurement system for an extracorporeal circuit having a rotating permanent magnetic excitation scheme is described in this paper. The system consists of a set of permanent magnets rotating near blood or any conductive fluid to create high-intensity alternating magnetic field in it and inducing a sinusoidal varying voltage across the column of fluid. The induced voltage signal is acquired, conditioned and processed to determine its flow rate. Performance analysis shows that a sensitivity of more than 250 mV/lpm can be obtained, which is more than five times higher than conventional flow measurement systems. Choice of rotating permanent magnet instead of an electromagnetic core generates alternate magnetic field of smooth sinusoidal nature which in turn reduces switching and interference noises. These results in reduction in complex electronic circuitry required for processing the signal to a great extent and enable the flow measuring device to be much less costlier, portable and light weight. The signal remains steady even with changes in environmental conditions and has an accuracy of greater than 95%. This paper also describes the construction details of the prototype, the factors affecting sensitivity and detailed performance analysis at various operating conditions.

  8. Blood carbonyl protein measurement as a specific oxidative stress biomarker after intestinal reperfusion in rats Dosagem da proteína carbonilada sanguínea como biomarcador específico do estresse oxidativo após reperfusão intestinal em ratos

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    Márcio José Jamel


    Full Text Available PURPOSE: An experimental study was performed to investigate the use of protein carbonyl group as a specific biological marker for oxidative stress in a rat model of intestinal ischaemia-reperfusion. METHODS: Twenty four male Wistar rats were randomly distributed into three groups with eight animals each: Group 1 - Control group; Group 2 - Sham; Group 3 - Intestinal ischaemia by clamping ileal branches of the superior mesenteric artery for one hour, followed by another hour of reperfusion. Blood samples were taken in order to analyze the protein carbonyl level by Slot blotting assay. RESULTS: In group 3 a significant increase of protein carbonyl level was observed if compared to the homogenous levels of groups 1 and 2. CONCLUSION: From the results it may be concluded that the protein carbonylation may be used as a specific marker for measuring oxidative stress in rat intestinal reperfusion model.OBJETIVO: Realizou-se um estudo experimental com a finalidade de investigar o uso da proteína carbonilada como um marcador biológico específico do estresse oxidativo em um modelo de isquemia e reperfusão intestinal, em ratos. MÉTODOS: Vinte e quarto ratos da linhagem Wistar, machos foram distribuídos, aleatoriamente, em três grupos compostos por oito animais cada: Grupo 1 - Controle; Grupo 2 - Simulação e Grupo 3 - Submetido à isquemia, mediante clampeamento de ramos ileais da artéria mesentérica superior por uma hora, seguida de reperfusão, por igual período. Amostras sanguíneas obtidas foram utilizadas para analise dos níveis de proteína carbonilada, através do método Slot blotting. RESULTADOS: No grupo 3 houve uma elevação significante da concentração de proteína carbonilada sérica se comparada aos níveis sanguíneos homogêneos encontrados nos grupos 1 e 2. CONCLUSÃO: Fundamentado nos resultados é possível concluir que, a carbonilação protéica pode ser utilizada como um marcador específico para a mensuração do

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

    DEFF Research Database (Denmark)

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


    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...


    Directory of Open Access Journals (Sweden)

    Carlos G. Musso, MD. PhD.1,2, Manuel Vilas, MD.


    Full Text Available The concepts of renal perfusion pressure (RPP and renal blood flow (RBF are usually confused, but although they are intimately related, they are not strictly the same. RPP originates from the minute cardiac volume and is, therefore, the cause of RBF, which generates glomerular filtration and as a consequence, also induces the urinary flow. On the other hand, whereas RPP can be subject to fluctuations, the same happens to RBF though at a much lower level due to the existence of physiological mechanisms, such as self-regulation of the flow and tubule-glomerular feed-back. We conclude that there is a dependence of the RBF in relation with RPP, with the former acting as the final responsible of the glomerular filtration.

  11. Renal blood flow and metabolism after cold ischaemia

    DEFF Research Database (Denmark)

    Henriksen, J H; Petersen, H K


    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...

  12. [Cerebral blood flow assessment of preterm infants during respiratory therapy with the expiratory flow increase technique]. (United States)

    Bassani, Mariana Almada; Caldas, Jamil Pedro Siqueira; Netto, Abimael Aranha; Marba, Sérgio Tadeu Martins


    To assess the impact of respiratory therapy with the expiratory flow increase technique on cerebral hemodynamics of premature newborns. This is an intervention study, which included 40 preterm infants (≤34 weeks) aged 8-15 days of life, clinically stable in ambient air or oxygen catheter use. Children with heart defects, diagnosis of brain lesion and/or those using vasoactive drugs were excluded. Ultrasonographic assessments with transcranial Doppler flowmetry were performed before, during and after the increase in expiratory flow session, which lasted 5minutes. Cerebral blood flow velocity and resistance and pulsatility indices in the pericallosal artery were assessed. Respiratory physical therapy did not significantly alter flow velocity at the systolic peak (p=0.50), the end diastolic flow velocity (p=0.17), the mean flow velocity (p=0.07), the resistance index (p=0.41) and the pulsatility index (p=0.67) over time. The expiratory flow increase technique did not affect cerebral blood flow in clinically-stable preterm infants. Copyright © 2015 Sociedade de Pediatria de São Paulo. Publicado por Elsevier Editora Ltda. All rights reserved.

  13. Cerebral blood flow assessment of preterm infants during respiratory therapy with the expiratory flow increase technique

    Directory of Open Access Journals (Sweden)

    Mariana Almada Bassani


    Full Text Available Abstract Objective: To assess the impact of respiratory therapy with the expiratory flow increase technique on cerebral hemodynamics of premature newborns. Methods: This is an intervention study, which included 40 preterm infants (≤34 weeks aged 8-15 days of life, clinically stable in ambient air or oxygen catheter use. Children with heart defects, diagnosis of brain lesion and/or those using vasoactive drugs were excluded. Ultrasonographic assessments with transcranial Doppler flowmetry were performed before, during and after the increase in expiratory flow session, which lasted 5min. Cerebral blood flow velocity and resistance and pulsatility indices in the pericallosal artery were assessed. Results: Respiratory physical therapy did not significantly alter flow velocity at the systolic peak (p=0.50, the end diastolic flow velocity (p=0.17, the mean flow velocity (p=0.07, the resistance index (p=0.41 and the pulsatility index (p=0.67 over time. Conclusions: The expiratory flow increase technique did not affect cerebral blood flow in clinically-stable preterm infants.

  14. In vivo evaluation of femoral blood flow measured with magnetic resonance

    DEFF Research Database (Denmark)

    Henriksen, O; Ståhlberg, F; Thomsen, C;


    Quantitative measurements of blood flow based on magnetic resonance imaging (MRI) using conventional multiple spin echo sequences were evaluated in vivo in healthy young volunteers. Blood flow was measured using MRI in the femoral vein. The initial slope of the multiple spin echo decay curve...... that in vivo blood flow measurements made with MRI based on wash-out effects, commonly used in multiple spin echo imaging, do not give reliable absolute values for blood flow in the femoral artery or vein......., corrected for the T2 decay of non-flowing blood was used to calculate the blood flow. As a reference, the blood flow in the femoral artery was measured simultaneously with an invasive indicator dilution technique. T2 of non-flowing blood was measured in vivo in popliteal veins during regional circulatory...

  15. A model of blood flow in the mesenteric arterial system

    Directory of Open Access Journals (Sweden)

    Cheng Leo K


    Full Text Available Abstract Background There are some early clinical indicators of cardiac ischemia, most notably a change in a person's electrocardiogram. Less well understood, but potentially just as dangerous, is ischemia that develops in the gastrointestinal system. Such ischemia is difficult to diagnose without angiography (an invasive and time-consuming procedure mainly due to the highly unspecific nature of the disease. Understanding how perfusion is affected during ischemic conditions can be a useful clinical tool which can help clinicians during the diagnosis process. As a first step towards this final goal, a computational model of the gastrointestinal system has been developed and used to simulate realistic blood flow during normal conditions. Methods An anatomically and biophysically based model of the major mesenteric arteries has been developed to be used to simulate normal blood flows. The computational mesh used for the simulations has been generated using data from the Visible Human project. The 3D Navier-Stokes equations that govern flow within this mesh have been simplified to an efficient 1D scheme. This scheme, together with a constitutive pressure-radius relationship, has been solved numerically for pressure, vessel radius and velocity for the entire mesenteric arterial network. Results The computational model developed shows close agreement with physiologically realistic geometries other researchers have recorded in vivo. Using this model as a framework, results were analyzed for the four distinct phases of the cardiac cycle – diastole, isovolumic contraction, ejection and isovolumic relaxation. Profiles showing the temporally varying pressure and velocity for a periodic input varying between 10.2 kPa (77 mmHg and 14.6 kPa (110 mmHg at the abdominal aorta are presented. An analytical solution has been developed to model blood flow in tapering vessels and when compared with the numerical solution, showed excellent agreement. Conclusion An

  16. Laser speckle contrast imaging to measure changes in cerebral blood flow. (United States)

    Winship, Ian R


    Laser speckle contrast imaging (LSCI) is a powerful tool capable of acquiring detailed maps of blood flow in arteries and veins on the cortical surface. Based on the blurring of laser speckle patterns by the motion of blood cells, LSCI can be combined with a variety of optical imaging preparations to acquire high-spatiotemporal resolution images of blood flow, and track changes in blood flow over time, using relatively simple instrumentation. Here, we describe methods for LSCI of cerebral blood flow via a thin skull imaging preparation in mice or rats. This preparation allows precise semiquantitative mapping of changes in blood flow over time using straightforward surgical protocols and equipment.

  17. High-throughput 13-parameter immunophenotyping identifies shifts in the circulating T-cell compartment following reperfusion in patients with acute myocardial infarction.

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    Jedrzej Hoffmann

    Full Text Available RATIONALE: With the advent of primary PCI (PPCI, reperfusion is achieved in almost all patients presenting with acute myocardial infarction. However, despite multiple trials, reperfusion injury has not been successfully dealt with so far. In mouse models, CD4(+ T lymphocytes (T cells have been shown to be crucial instigators of reperfusion injury. OBJECTIVE: Our goal was to investigate the role of CD4(+ T cells during myocardial reperfusion following PPCI by developing a protocol for high-throughput multiplexed flow cytometric analysis and multivariate flow clustering. METHODS AND RESULTS: 13-parameter immunophenotyping and hierarchical cluster analysis (HCA identified a unique CD4(+CD57(+ T-cell population in PPCI patients that reflected acute proliferation in the CD4(+ T-cell compartment. CD4(+CCR7(+ T cells were specifically depleted from peripheral blood during the first 30 min of myocardial reperfusion after PPCI, suggesting a potential role for the chemokine receptor CCR7 in T-cell redistribution to either peripheral tissues or migration to the infarcted heart during ischemia/reperfusion following PPCI. CONCLUSIONS: High-throughput polychromatic flow cytometry and HCA are capable of objective, time and cost efficient assessment of the individual T-cell immune profile in different stages of coronary heart disease and have broad applications in clinical trials.

  18. Quantification of myocardial blood flow and blood flow reserve in the presence of arterial dispersion: a simulation study. (United States)

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


    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.

  19. Fetal blood flow measurements in severe rhesus isoimmunization. A case report. (United States)

    Stiller, R J; Ashmead, G G; Paul, D; Weiner, S


    Maternal isoimmunization can result in fetal anemia. Current management of isoimmunized pregnancies involves amniocentesis and spectrophotometry. Pulsed Doppler ultrasound can provide fetal blood flow determinations from the fetal umbilical vein. A pregnancy complicated by severe rhesus isoimmunization was studied with Doppler ultrasound. Increased fetal umbilical blood flow was associated with increased fetal hemolysis. Umbilical vein blood flow decreased after intrauterine transfusion. Doppler ultrasound assessment of fetal blood flow is a useful noninvasive adjunct in isoimmunized pregnancies.

  20. Uncertainty quantification in coronary blood flow simulations: Impact of geometry, boundary conditions and blood viscosity. (United States)

    Sankaran, Sethuraman; Kim, Hyun Jin; Choi, Gilwoo; Taylor, Charles A


    Computational fluid dynamic methods are currently being used clinically to simulate blood flow and pressure and predict the functional significance of atherosclerotic lesions in patient-specific models of the coronary arteries extracted from noninvasive coronary computed tomography angiography (cCTA) data. One such technology, FFRCT, or noninvasive fractional flow reserve derived from CT data, has demonstrated high diagnostic accuracy as compared to invasively measured fractional flow reserve (FFR) obtained with a pressure wire inserted in the coronary arteries during diagnostic cardiac catheterization. However, uncertainties in modeling as well as measurement results in differences between these predicted and measured hemodynamic indices. Uncertainty in modeling can manifest in two forms - anatomic uncertainty resulting in error of the reconstructed 3D model and physiologic uncertainty resulting in errors in boundary conditions or blood viscosity. We present a data-driven framework for modeling these uncertainties and study their impact on blood flow simulations. The incompressible Navier-Stokes equations are used to model blood flow and an adaptive stochastic collocation method is used to model uncertainty propagation in the Navier-Stokes equations. We perform uncertainty quantification in two geometries, an idealized stenosis model and a patient specific model. We show that uncertainty in minimum lumen diameter (MLD) has the largest impact on hemodynamic simulations, followed by boundary resistance, viscosity and lesion length. We show that near the diagnostic cutoff (FFRCT=0.8), the uncertainty due to the latter three variables are lower than measurement uncertainty, while the uncertainty due to MLD is only slightly higher than measurement uncertainty. We also show that uncertainties are not additive but only slightly higher than the highest single parameter uncertainty. The method presented here can be used to output interval estimates of hemodynamic indices

  1. Cerebral lactate production and blood flow in acute stroke

    DEFF Research Database (Denmark)

    Henriksen, O; Gideon, P; Sperling, B


    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...... phase probably does not reflect the degree of anaerobic glycolysis in hypoxic neuronal tissue....

  2. Resistance exercise with different volumes: blood pressure response and forearm blood flow in the hypertensive elderly. (United States)

    Brito, Aline de Freitas; de Oliveira, Caio Victor Coutinho; Brasileiro-Santos, Maria do Socorro; Santos, Amilton da Cruz


    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. The study was conducted with ten hypertensive elderly (65±3 years, 28.7±3 kg/m(2)) 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. 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, Pexercises 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 resistance.


    Directory of Open Access Journals (Sweden)

    H. Mazaher


    Full Text Available Vertebrobasilar insufficiency is the cause of cerebrovascular accidents in 20% of cases. There are few reports regarding spectral Doppler indices (SDIs of vertebral arteries (VAs normal blood flow. The objective of this study was to provide basic reference data about SDIs of VAs normal blood flow separately and in comparison with internal carotid arteries (ICAs and common carotid arteries (CCAs normal blood flows SDIs. This cross-sectional study performed on 70 normal patients. Color Doppler sonography (CDS and spectral Doppler sonography (SDS of right and left VAs (RVA and LVA, right and left CCAs (RCCA and LCCA, right and left ICAs (RICA and LICA, were performed. The mean PSV, EDV, and RI values of RVA blood flow were as 41.60 ± 9.6 cm/s, 14.60 ± 3.7 cm/s and 0.65 ± 0.06, and the mean PSV, EDV and RI values of LVA blood flow were as 42.20 ± 10.2 cm/s, 15.20 ± 4.2 cm/s, and 0.64 ± 0.05, respectively. There was not statistically significant difference between the mean PSV, EDV and RI values of RVA and LVA blood flows. The mean PSV and EDV values of VAs blood flows were significantly lower than the values of CCAs and ICCAs blood flows, respectively. The mean RI value of VAs blood flows was significantly lower than the mean RI Value of CCAs blood flows, but there was not statistically significant difference between the mean RI value of VAs blood flows and the mean RI value of ICAs blood flows.

  4. Resistance exercise with different volumes: blood pressure response and forearm blood flow in the hypertensive elderly

    Directory of Open Access Journals (Sweden)

    Brito AF


    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

  5. Intermittent Ischemia but Not Ischemic Preconditioning Is Effective in Restoring Bile Flow After Ischemia Reperfusion Injury in the Livers of Aged Rats

    NARCIS (Netherlands)

    Schiesser, Marc; Wittert, Anna; Nieuwenhuijs, Vincent B.; Morphett, Arthur; Padbury, Robert T. A.; Barritt, Greg J.


    BackgroundlAims. Ischemic preconditioning (IPC) and intermittent ischemia (INT) reduce liver injury following ischemia reperfusion in liver resections. Aged livers are at higher risk for ischemia reperfusion injury, but little is known of the effectiveness of IPC and INT in aged livers. The aim of t

  6. Mucosal/submucosal blood flow in the gut wall determined by local washout of 133Xenon

    DEFF Research Database (Denmark)

    Mortensen, Peter; Olsen, J; Bülow, J


    the initial slope of the washout was used for measuring blood flow rate. Blood flow rate was simultaneously measured by microsphere entrapment technique. There was an excellent correlation between the blood flow rate determined by the two techniques the correlation coefficient R being 0.89 in the small...

  7. Form, shape and function: segmented blood flow in the choriocapillaris (United States)

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


    The development of fluid transport systems was a key event in the evolution of animals and plants. While within vertebrates branched geometries predominate, the choriocapillaris, which is the microvascular bed that is responsible for the maintenance of the outer retina, has evolved a planar topology. Here we examine the flow and mass transfer properties associated with this unusual geometry. We show that as a result of the form of the choriocapillaris, the blood flow is decomposed into a tessellation of functional vascular segments of various shapes delineated by separation surfaces across which there is no flow, and in the vicinity of which the transport of passive substances is diffusion-limited. The shape of each functional segment is determined by the distribution of arterioles and venules and their respective relative flow rates. We also show that, remarkably, the mass exchange with the outer retina is a function of the shape of each functional segment. In addition to introducing a novel framework in which the structure and function of the metabolite delivery system to the outer retina may be investigated in health and disease, the present work provides a general characterisation of the flow and transfers in multipole Hele-Shaw configurations.

  8. Heterogeneity of cerebral blood flow: a fractal approach

    Energy Technology Data Exchange (ETDEWEB)

    Kuikka, J.T.; Hartikainen, P. [Department of Clinical Physiology, Kuopioo Univ. Hospital (Finland); Department of Neurology, Kuopio Univ. Hosspital (Finland); Niuvanniemi Hospital, Kuopio (Finland)


    Aim: We demonstrate the heterogeneity of regional cerebral blood flow using a fractal approach and single-photon emission computed tomography (SPECT). Method: Tc-99m-labelled ethylcysteine dimer was injected intravenously in 10 healthy controls and in 10 patients with dementia of frontal lobe type. The head was imaged with a gamma camera and transaxial, sagittal and coronal slices were reconstructed. Two hundred fifty-six symmetrical regions of interest (ROIs) were drawn onto each hemisphere of functioning brain matter. Fractal analysis was used to examine the spatial heterogeneity of blood flow as a function of the number of ROIs. Results: Relative dispersion (=coefficient of variation of the regional flows) was fractal-like in healthy subjects and could be characterized by a fractal dimension of 1.17{+-}0.05 (mean{+-}SD) for the left hemisphere and 1.15{+-}0.04 for the right hemisphere, respectively. The fractal dimension of 1.0 reflects completely homogeneous blood flow and 1.5 indicates a random blood flow distribution. Patients with dementia of frontal lobe type had a significantly lower fractal dimension of 1.04{+-}0.03 than in healthy controls. (orig.) [German] Ziel: Unter Einsatz einer fraktalen Annaeherung und SPECT wird die Heterogenitaet der regionalen Hirndruchblutung demonstriert. Methode: Tc-99m-ECD wurde nach intravenoeser Injektion bei zehn Gesunden sowie bei zehn Patienten mit Demenz vom Frontallappen-Typ eingesetzt. Aus dem SPECT-Umlauf wurden transaxiale, sagittale und koronare Schnitte rekonstruiert. 265 symmetrische Regions of Interest wurden im Gebiet der funktionellen grauen Substanz fuer jede Hemisphaere markiert. Die fraktale Analyse wurde eingesetzt zur Bestimmung der raeumlichen Heterogenitaet der Hirndurchblutung als Funktion der ROI-Anzahl. Ergebnisse: Die relative Streuung (Variationskoeffizient der regionalen Durchblutung) war bei Gesunden fraktalaehnlich geordnet und konnte durch eine Fraktaldimension von 1,17{+-}0,05 (Mittelwert

  9. Testing of models of flow-induced hemolysis in blood flow through hypodermic needles. (United States)

    Chen, Yangsheng; Kent, Timothy L; Sharp, M Keith


    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. © 2013, Copyright the Authors. Artificial Organs © 2013, International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.

  10. Tracking flow of leukocytes in blood for drug analysis (United States)

    Basharat, Arslan; Turner, Wesley; Stephens, Gillian; Badillo, Benjamin; Lumpkin, Rick; Andre, Patrick; Perera, Amitha


    Modern microscopy techniques allow imaging of circulating blood components under vascular flow conditions. The resulting video sequences provide unique insights into the behavior of blood cells within the vasculature and can be used as a method to monitor and quantitate the recruitment of inflammatory cells at sites of vascular injury/ inflammation and potentially serve as a pharmacodynamic biomarker, helping screen new therapies and individualize dose and combinations of drugs. However, manual analysis of these video sequences is intractable, requiring hours per 400 second video clip. In this paper, we present an automated technique to analyze the behavior and recruitment of human leukocytes in whole blood under physiological conditions of shear through a simple multi-channel fluorescence microscope in real-time. This technique detects and tracks the recruitment of leukocytes to a bioactive surface coated on a flow chamber. Rolling cells (cells which partially bind to the bioactive matrix) are detected counted, and have their velocity measured and graphed. The challenges here include: high cell density, appearance similarity, and low (1Hz) frame rate. Our approach performs frame differencing based motion segmentation, track initialization and online tracking of individual leukocytes.

  11. Numerical Simulations of Blood Flows in the Left Atrium (United States)

    Zhang, Lucy


    A novel numerical technique of solving complex fluid-structure interactions for biomedical applications is introduced. The method is validated through rigorous convergence and accuracy tests. In this study, the technique is specifically used to study blood flows in the left atrium, one of the four chambers in the heart. Stable solutions are obtained at physiologic Reynolds numbers by applying pulmonary venous inflow, mitral valve outflow and appropriate constitutive equations to closely mimic the behaviors of biomaterials. Atrial contraction is also implemented as a time-dependent boundary condition to realistically describe the atrial wall muscle movements, thus producing accurate interactions with the surrounding blood. From our study, the transmitral velocity, filling/emptying velocity ratio, durations and strengths of vortices are captured numerically for sinus rhythms (healthy heart beat) and they compare quite well with reported clinical studies. The solution technique can be further used to study heart diseases such as the atrial fibrillation, thrombus formation in the chamber and their corresponding effects in blood flows.

  12. Autoregulation of cerebral blood flow in orthostatic hypotension (United States)

    Novak, V.; Novak, P.; Spies, J. M.; Low, P. A.


    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.

  13. Theoretical model of blood flow measurement by diffuse correlation spectroscopy (United States)

    Sakadžić, Sava; Boas, David A.; Carp, Stefan


    Diffuse correlation spectroscopy (DCS) is a noninvasive method to quantify tissue perfusion from measurements of the intensity temporal autocorrelation function of diffusely scattered light. However, DCS autocorrelation function measurements in tissue better match theoretical predictions based on the diffusive motion of the scatterers than those based on a model where the advective nature of blood flow dominates the stochastic properties of the scattered light. We have recently shown using Monte Carlo (MC) simulations and assuming a simplistic vascular geometry and laminar flow profile that the diffusive nature of the DCS autocorrelation function decay is likely a result of the shear-induced diffusion of the red blood cells. Here, we provide theoretical derivations supporting and generalizing the previous MC results. Based on the theory of diffusing-wave spectroscopy, we derive an expression for the autocorrelation function along the photon path through a vessel that takes into account both diffusive and advective scatterer motion, and we provide the solution for the DCS autocorrelation function in a semi-infinite geometry. We also derive the correlation diffusion and correlation transfer equation, which can be applied for an arbitrary sample geometry. Further, we propose a method to take into account realistic vascular morphology and flow profile.

  14. Laser Doppler flowmetry for bone blood flow measurement: correlation with microsphere estimates and evaluation of the effect of intracapsular pressure on femoral head blood flow

    Energy Technology Data Exchange (ETDEWEB)

    Swiontkowski, M.F.; Tepic, S.; Perren, S.M.; Moor, R.; Ganz, R.; Rahn, B.A.


    Laser Doppler flowmetry (LDF) was used to measure bone blood flow in the rabbit femoral condyles. To correlate the LDF output signal blood cell flux to in vivo blood flow, simultaneous measurements using LDF and /sup 85/Sr-labeled microspheres were made in an adult rabbit model. There was no correlation between the two methods for blood flow in the femoral condyles and the correlation between the two methods for blood flow in the femoral head does not achieve statistical significance. An LDF signal of 0.4 V was approximately equal to a microsphere measured flow rate of 0.4 ml blood/g bone/min. The strength of the correlation in the latter case may have been affected by (a) large arteriovenous shunts, (b) inadequate mixing of the microspheres with a left ventricular injection, and (c) insufficient numbers of microspheres present in the bone samples. When LDF was used to evaluate the effect of elevated intracapsular pressure on femoral head blood flow in skeletally mature rabbits, femoral head subchondral bone blood flow declined with increasing intracapsular pressure from a baseline value of 0.343 +/- 0.036 to a value of 0.127 +/- 0.27 at 120 cm of water pressure. The decline in femoral head blood flow was statistically significant at pressures of 40 cm of water or higher (p less than 0.001), and evaluation of sections of the proximal femora made from preterminal disulphine blue injections confirmed these findings. Intracapsular tamponade has an adverse effect on femoral head blood flow beginning well below central venous pressure and should be considered in the pathophysiology of posttraumatic and nontraumatic necrosis of the femoral head. Laser Doppler flowmetry was easy to use and appears to be a reproducible technique for evaluating femoral head blood flow, offering distinct advantages over the microsphere technique for measuring bone blood flow.

  15. Effects of L-alanyl-glutamine upon the blood and kidney biochemical parameters in the rat hind limb model of ischemia/reperfusion Efeitos da L-alanil-glutamina sobre os parâmetros bioquímicos do sangue e do rim no rato submetido à isquemia/reperfusão do membro pélvico



    PURPOSE: To investigate the effects of l-alanyl-glutamine (Ala-Gln) intragastric administration upon blood and kidney metabolic parameters alterations in rats subjected to ischemia/reperfusion of hind limb. METHODS: Forty-eight male rats were randomized in 2 groups offered via gavage either saline 2.0 mL (G-1) or Ala-Gln solution 0.75 mgKg-1(G-2) once a day at 7 AM during 7 days. One-hour after the last gavage (Day 7) all rats were submitted to ether anesthesia, laparotomy and clamping of the...

  16. Measurement of anterior and posterior circulation flow contributions to cerebral blood flow. An ultrasound-derived volumetric flow analysis. (United States)

    Boyajian, R A; Schwend, R B; Wolfe, M M; Bickerton, R E; Otis, S M


    Ultrasound-derived volumetric flow analysis may be useful in answering questions of basic physiological interest in the cerebrovascular circulation. Using this technique, the authors have sought to describe quantitatively the complete concurrent flow relations among all four arteries supplying the brain. The aim of this study of normal subjects was to determine the relative flow contributions of the anterior (internal carotid arteries) and posterior (vertebral arteries) cerebral circulation. Comparisons between the observed and theoretically expected anterior and posterior flow distribution would provide an opportunity to assess traditional rheological conceptions in vivo. Pulsed color Doppler ultrasonography was used to measure mean flow rates in the internal carotid and vertebral arteries in 21 normal adults. The anterior circulation (internal carotid arteries bilaterally) carried 82% of the brain's blood supply and comprised 67% of the total vascular cross-sectional area. These values demonstrate precise concordance between observations in vivo and the theoretically derived (Hagen-Poiseuille) expected flow distribution. These cerebrovascular findings support the traditional conception of macroscopic blood flow. Further studies using ultrasound-derived volumetric analysis of the brain's arterial flow relations may illuminate the vascular pathophysiology underlying aging, cerebral ischemia, and dementias.

  17. Cerebral blood flow autoregulation in experimental liver failure

    DEFF Research Database (Denmark)

    Dethloff, T.J.; Larsen, F.S.; Knudsen, Gitte Moos


    Patients with acute liver failure (ALF) display impairment of cerebral blood flow (CBF) autoregulation, which may contribute to the development of fatal intracranial hypertension, but the pathophysiological mechanism remains unclear. In this study, we examined whether loss of liver mass causes...... impairment of CBF autoregulation. Four rat models were chosen, each representing different aspects of ALF: galactosamine (GlN) intoxication represented liver necrosis, 90% hepatectomy (PHx90) represented reduction in liver mass, portacaval anastomosis (PCA) represented shunting of blood....../toxins into the systemic circulation thus mimicking intrahepatic shunting in ALF, PCA+NH(3) provided information about the additional effects of hyperammonemia Rats were intubated and sedated with pentobarbital. We measured CBF with laser Doppler, intracranial pressure (ICP) was measured in the fossa posterior...

  18. Interactive retinal blood flow analysis of the macular region. (United States)

    Tian, Jing; Somfai, Gábor Márk; Campagnoli, Thalmon R; Smiddy, William E; Debuc, Delia Cabrera


    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). Copyright © 2015 Elsevier Inc. All rights reserved.

  19. Effects of exercise training with blood flow restriction on blood pressure in medicated hypertensive patients

    Directory of Open Access Journals (Sweden)

    Marcos Antônio Cezar


    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.

  20. Dynamics of renal blood flow autoregulation in rats

    DEFF Research Database (Denmark)

    Holstein-Rathlou, N H; Wagner, A J; Marsh, D J


    Two separate components could be resolved in tests of the dynamic autoregulation of renal blood flow. The slow component corresponds to the frequency at which spontaneous proximal tubular pressure oscillations are found, and are most likely due to the operation of the TGF. The high frequency...... component most likely represents an intrinsic vascular, myogenic, mechanism. The gain maximum of the admittance in the frequency range corresponding to the autonomous tubular oscillations indicates that the dynamic characteristics responsible for the occurrence of the spontaneous tubular oscillations must...

  1. Endoscopic retrograde cholangiopancreatography causes reduced myocardial blood flow

    DEFF Research Database (Denmark)

    Christensen, M; Hendel, H W; Rasmussen, V;


    ). 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...

  2. Skin blood flow with elastic compressive extravehicular activity space suit. (United States)

    Tanaka, Kunihiko; Gotoh, Taro M; Morita, Hironobu; Hargens, Alan R


    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.

  3. Oscillations and chaos in renal blood flow control

    DEFF Research Database (Denmark)

    Holstein-Rathlou, N H


    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...... studies show that the key parameters determining the stability of the TGF system are the open loop gain of the system and the time delays in the signal transmission through the various components of the feedback loop. Within a broad range of parameters, the system is unstable and has self-sustained stable...

  4. Regional cerebral blood flow and blood volume in patients with subcortical arteriosclerotic encephalopathy (SAE). (United States)

    Gückel, Friedemann J; Brix, Gunnar; Hennerici, Michael; Lucht, Robert; Ueltzhöffer, Christine; Neff, Wolfgang


    The aim of the present study was a detailed analysis of the regional cerebral blood flow and blood volume in patients with subcortical arteriosclerotic encephalopathy (SAE) by means of functional magnetic resonance imaging (MRI). A group of 26 patients with SAE and a group of 16 age-matched healthy volunteers were examined. Using a well-established dynamic susceptibility contrast-enhanced MRI method, the regional cerebral blood flow (rCBF) and blood volume (rCBV) were quantified for each subject in 12 different regions in the brain parenchyma. As compared to healthy volunteers, patients with SAE showed significantly reduced rCBF and rCBV values in white matter regions and in the occipital cortex. Regions containing predominantly grey matter show almost normal rCBF and rCBV values. In conclusion, quantitative analysis of rCBF and rCBV values demonstrates clearly that SAE is a disease that is associated with a reduced microcirculation predominantly in white matter.

  5. 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


    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 ...

  6. In-vitro laser anemometry blood flow systems (United States)

    Liepsch, Dieter W.; Poll, Axel; Pflugbeil, Gottlieb


    Lasers are used in a wide variety of medical applications. While laser catheters have been developed for highly accurate velocity measurements these are invasive; noninvasive techniques are more desirable but not as precise. The laser is, however, a great tool for in vitro measurements. Several groups internationally are using the laser in the study of local velocity distribution in microscopic areas of specially constructed models. Laser Doppler anemometry is widely used to measure the local, time-dependent velocities, while phase Doppler anemometry has been developed to measure particle size, distribution and velocity. Most recently, laser analyzer techniques have been developed for analyzing the particle size of two phase flow systems. It has become increasingly important for physicians to visualize blood flow. In addition to the techniques mentioned above, several laser sheet techniques have been developed for precise measurements. This paper presents a short review of laser techniques and shows some applications especially for the laser-Doppler anemometer.

  7. Validation of Blood Flow Simulations in Intracranial Aneurysms (United States)

    Yu, Yue; Anor, Tomer; Baek, Hyoungsu; Jayaraman, Mahesh; Madsen, Joseph; Karniadakis, George


    Catheter-based digital subtraction angiography (DSA) is the most accurate diagnostic procedure for investigating vascular anomalies and cerebral blood flow. Here we describe utilization of DSA in a patient with an intracranial aneursysm to validate corresponding spectral element simulations. Subsequently, we examine via visualization the structure of flow in internal carotid arteries laden with three different types of aneurysms: (1) a wide-necked saccular aneurysm, (2) a narrower-necked saccular aneurysm, and (3) a case with two adjacent saccular aneurysms. We have found through high resolution simulations that in cases (1) and (3) in physiological conditions a hydrodynamic instability occurs during the decelerating systolic phase resulting in a high frequency oscillation (20-50 Hz). We use the in-silico dye visualization to discriminate among different physical mechanisms causing the instability and contrast their effect with case (2) for which an instability arises only at much higher flowrates.

  8. Numerical Simulation of Unsteady Blood Flow through Capillary Networks. (United States)

    Davis, J M; Pozrikidis, C


    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.

  9. A reconstruction method of intra-ventricular blood flow using color flow ultrasound: a simulation study (United States)

    Jang, Jaeseong; Ahn, Chi Young; Jeon, Kiwan; Choi, Jung-il; Lee, Changhoon; Seo, Jin Keun


    A reconstruction method is proposed here to quantify the distribution of blood flow velocity fields inside the left ventricle from color Doppler echocardiography measurement. From 3D incompressible Navier- Stokes equation, a 2D incompressible Navier-Stokes equation with a mass source term is derived 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. For demonstrating a feasibility of the proposed method, we have performed numerical simulations of the forward problem and numerical analysis of the reconstruction method. First, we construct a 3D moving LV region having a specific stroke volume. To obtain synthetic intra-ventricular flows, we performed a numerical simulation of the forward problem of Navier-Stokes equation inside the 3D moving LV, computed 3D intra-ventricular velocity fields as a solution of the forward problem, projected the 3D velocity fields on the imaging plane and took the inner product of the 2D velocity fields on the imaging plane and scanline directional velocity fields for synthetic scanline directional projected velocity at each position. The proposed method utilized the 2D synthetic projected velocity data for reconstructing LV blood flow. By computing the difference between synthetic flow and reconstructed flow fields, we obtained the averaged point-wise errors of 0.06 m/s and 0.02 m/s for u- and v-components, respectively.

  10. Human red blood cells deformed under thermal fluid flow. (United States)

    Foo, Ji-Jinn; Chan, Vincent; Feng, Zhi-Qin; Liu, Kuo-Kang


    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.

  11. Early recovery of microvascular perfusion induced by t-PA in combination with abciximab or eptifibatide during postischemic reperfusion

    Directory of Open Access Journals (Sweden)

    Giusti Andrea


    Full Text Available Abstract Background GPIIb/IIIa inhibitors abciximab and eptifibatide have been shown to inhibit platelet aggregation in ischemic heart disease. Our aim was to test the efficacy of abiciximab (Reo Pro or eptifibatide (Integrilin alone or in combination with plasminogen activator (t-PA in an experimental model of ischemia reperfusion (I/R in hamster cheek pouch microcirculation visualized by fluorescence microscopy. Hamsters were treated with saline, or abiciximab or eptifibatide or these drugs combined with t-PA infused intravenously 10 minutes before ischemia and through reperfusion. We measured the microvessel diameter changes, the arteriolar red blood cell (RBC velocity, the increase in permeability, the perfused capillary length (PCL, and the platelet and leukocyte adhesion on microvessels. Results I/R elicited large increases in the platelet and leukocyte adhesion and a decrease in microvascular perfusion. These responses were significantly attenuated by abiciximab or eptifibatide (PCL:70 and 65% at 5–10 mins of reperfusion and 85 and 87% at 30 mins of reperfusion, respectively, p Conclusions Platelets are crucial in I/R injury, as shown by the treatment with abicixmab or eptifibatide, which decreased platelet aggregation in microvessels, and also decreased leukocyte adhesion in venules. Arterial vasoconstriction, decreased arterial RBC velocity and alterations in the endothelial barrier with increased permeability delayed the complete restoration of blood flow, while t-PA combined with inhibition of platelet aggregation speeded up the capillary perfusion after reperfusion.

  12. 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)


    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

  13. Monitoring blood flow and photobleaching during topical ALA PDT treatment (United States)

    Sands, Theresa L.; Sunar, Ulas; Foster, Thomas H.; Oseroff, Allan R.


    Photodynamic therapy (PDT) using topical aminolevulinic acid (ALA) is currently used as a clinical treatment for nonmelanoma skin cancers. In order to optimize PDT treatment, vascular shutdown early in treatment must be identified and prevented. This is especially important for topical ALA PDT where vascular shutdown is only temporary and is not a primary method of cell death. Shutdown in vasculature would limit the delivery of oxygen which is necessary for effective PDT treatment. Diffuse correlation spectroscopy (DCS) was used to monitor relative blood flow changes in Balb/C mice undergoing PDT at fluence rates of 10mW/cm2 and 75mW/cm2 for colon-26 tumors implanted intradermally. DCS is a preferable method to monitor the blood flow during PDT of lesions due to its ability to be used noninvasively throughout treatment, returning data from differing depths of tissue. Photobleaching of the photosensitizer was also monitored during treatment as an indirect manner of monitoring singlet oxygen production. In this paper, we show the conditions that cause vascular shutdown in our tumor model and its effects on the photobleaching rate.

  14. Clustering of microscopic particles in constricted blood flow (United States)

    Bächer, Christian; Schrack, Lukas; Gekle, Stephan


    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 of 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 have important physiological consequences, e.g., for the formation of microthrombi.

  15. Multiscale modeling and simulation of brain blood flow

    Energy Technology Data Exchange (ETDEWEB)

    Perdikaris, Paris, E-mail: [Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Grinberg, Leopold, E-mail: [IBM T.J Watson Research Center, 1 Rogers St, Cambridge, Massachusetts 02142 (United States); Karniadakis, George Em, E-mail: [Division of Applied Mathematics, Brown University, Providence, Rhode Island 02912 (United States)


    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.

  16. Clustering of microscopic particles in constricted blood flow

    CERN Document Server

    Bächer, Christian; Gekle, Stephan


    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...

  17. Adipose tissue and skeletal muscle blood flow during mental stress

    Energy Technology Data Exchange (ETDEWEB)

    Linde, B.; Hjemdahl, P.; Freyschuss, U.; Juhlin-Dannfelt, A.


    Mental stress (a modified Stroop color word conflict test (CWT)) increased adipose tissue blood flow (ATBF; 133Xe clearance) by 70% and reduced adipose tissue vascular resistance (ATR) by 25% in healthy male volunteers. The vasculatures of adipose tissue (abdomen as well as thigh), skeletal muscle of the calf (133Xe clearance), and the entire calf (venous occlusion plethysmography) responded similarly. Arterial epinephrine (Epi) and glycerol levels were approximately doubled by stress. Beta-Blockade by metoprolol (beta 1-selective) or propranolol (nonselective) attenuated CWT-induced tachycardia similarly. Metoprolol attenuated stress-induced vasodilation in the calf and tended to do so in adipose tissue. Propranolol abolished vasodilation in the calf and resulted in vasoconstriction during CWT in adipose tissue. Decreases in ATR, but not in skeletal muscle or calf vascular resistances, were correlated to increases in arterial plasma glycerol (r = -0.42, P less than 0.05), whereas decreases in skeletal muscle and calf vascular resistances, but not in ATR, were correlated to increases in arterial Epi levels (r = -0.69, P less than 0.01; and r = -0.43, P less than 0.05, respectively). The results suggest that mental stress increases nutritive blood flow in adipose tissue and skeletal muscle considerably, both through the elevation of perfusion pressure and via vasodilatation. Withdrawal of vasoconstrictor nerve activity, vascular beta 2-adrenoceptor stimulation by circulating Epi, and metabolic mechanisms (in adipose tissue) may contribute to the vasodilatation.

  18. Local blood flow measured by fluorescence excitation of nonradioactive microspheres

    Energy Technology Data Exchange (ETDEWEB)

    Morita, Y.; Payne, B.D.; Aldea, G.S.; McWatters, C.; Husseini, W.; Mori, H.; Hoffman, J.I.; Kaufman, L. (Univ. of California, San Francisco (USA))


    An X-ray fluorescence system with low Compton background and high counting efficiency was developed to measure regional blood flow with nonradioactive microspheres. The performance of the system was tested in vitro by counting mixed aqueous solutions of either Mo, Ag, and I; Nb, Ag, and Ba; or Zr, Mo, Rh, Ag, Sn, I, and Ba, as well as a mixture of Ag and Ba nonradioactive microspheres. Mixtures containing 2-20 ppm of each element were counted for 10 min by the fluorescence system, and the individual elements in mixtures of three to seven nonradioactive elements were measured with high accuracy. The best counting statistics were obtained for Ag. For 10-min counts, the system measures as few as 120 Ag microspheres with 30% standard deviation but measures 800 Ag microspheres per sample with 3.6% standard deviation. We compared regional myocardial blood flows determined simultaneously by fluorescence and radioactive microsphere methods; the latter samples were counted by a 3-in. NaI (Tl) well detector and pulse-height analyzer. The radioactive and nonradioactive measurements showed good correlations.

  19. Developmental validation of a novel lateral flow strip test for rapid identification of human blood (Rapid Stain Identification--Blood). (United States)

    Schweers, Brett A; Old, Jennifer; Boonlayangoor, P W; Reich, Karl A


    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. 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.


    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...... of control mechanisms are included: 1) autonomic regulation mediated by sympathetic and parasympathetic responses, which affect heart rate, cardiac contractility, resistance, and compliance, and 2) autoregulation mediated by responses to local changes in myogenic tone, metabolic demand, and CO2 concentration...

  1. Role of Kupffer cells in reperfusion injury in fat-loaded livers from ethanol-treated rats. (United States)

    Zhong, Z; Connor, H D; Mason, R P; Qu, W; Gao, W; Lemasters, J J; Thurman, R G


    Reperfusion injury was studied in blood-free perfused livers from fat-loaded, ethanol-treated rats. Rats were pair-fed a modified Lieber-DeCarli liquid diet containing 36% calories as ethanol or isocaloric maltose-dextrin for 4 to 5 weeks. Reperfusion injury to the liver, which occurs in previously hypoxic regions upon reintroduction of oxygen, was studied in a low-flow, reflow perfusion model. Lactate dehydrogenase in effluent perfusate increased from basal levels of < 1 to 17 IU/g/h in livers from controls, whereas prior alcohol treatment elevated values to 37 IU/g/h. Pretreatment of rats with gadolinium chloride (GdCl3, 20 mg/kg i.v.), a selective Kupffer cell toxicant, minimized lactate dehydrogenase release during reperfusion to 7 to 8 IU/g/h in livers from both groups. Rates of malondialdehyde production were 144 and 166 nmol/g/h during reperfusion in control and alcohol-treated rats, respectively, but values reached only 54 and 79 nmol/g/h after GdCl3 treatment. Interestingly, a typical PBN/carbon-centered free radical adduct signal was detected in bile of livers from ethanol-treated rats, but not in controls or ethanol-treated rats given GdCl3. Portal pressure increased during the reperfusion period in livers from alcohol-treated rats, although not in controls, and GdCl3 reduced it significantly. Taken together, these data indicate that reperfusion injury is greater in fatty livers from alcohol-treated rats in a blood-free model. Inactivation of Kupffer cells minimized reperfusion injury in both control and alcohol-treated rats, most likely by diminishing lipid peroxidation thereby improving hepatic microcirculation.

  2. Delayed reperfusion deficits after experimental stroke account for increased pathophysiology. (United States)

    Burrows, Fiona E; Bray, Natasha; Denes, Adam; Allan, Stuart M; Schiessl, Ingo


    Cerebral blood flow and oxygenation in the first few hours after reperfusion following ischemic stroke are critical for therapeutic interventions but are not well understood. We investigate changes in oxyhemoglobin (HbO2) concentration in the cortex during and after ischemic stroke, using multispectral optical imaging in anesthetized mice, a remote filament to induce either 30 minute middle cerebral artery occlusion (MCAo), sham surgery or anesthesia alone. Immunohistochemistry establishes cortical injury and correlates the severity of damage with the change of oxygen perfusion. All groups were imaged for 6 hours after MCAo or sham surgery. Oxygenation maps were calculated using a pathlength scaling algorithm. The MCAo group shows a significant drop in HbO2 during occlusion and an initial increase after reperfusion. Over the subsequent 6 hours HbO2 concentrations decline to levels below those observed during stroke. Platelets, activated microglia, interleukin-1α, evidence of BBB breakdown and neuronal stress increase within the stroked hemisphere and correlate with the severity of the delayed reperfusion deficit but not with the ΔHbO2 during stroke. Despite initial restoration of HbO2 after 30 min MCAo there is a delayed compromise that coincides with inflammation and could be a target for improved stroke outcome after thrombolysis.

  3. Effects of L-alanyl-glutamine upon the blood and kidney biochemical parameters in the rat hind limb model of ischemia/reperfusion Efeitos da L-alanil-glutamina sobre os parâmetros bioquímicos do sangue e do rim no rato submetido à isquemia/reperfusão do membro pélvico

    Directory of Open Access Journals (Sweden)

    Marcos Antonio Alves


    Full Text Available PURPOSE: To investigate the effects of l-alanyl-glutamine (Ala-Gln intragastric administration upon blood and kidney metabolic parameters alterations in rats subjected to ischemia/reperfusion of hind limb. METHODS: Forty-eight male rats were randomized in 2 groups offered via gavage either saline 2.0 mL (G-1 or Ala-Gln solution 0.75 mgKg-1(G-2 once a day at 7 AM during 7 days. One-hour after the last gavage (Day 7 all rats were submitted to ether anesthesia, laparotomy and clamping of the left iliac artery for 3 h. Kidney and blood samples were collected at the end of ischemic period (3h and at 1-3-6h during reperfusion period for metabolites (pyruvate, lactate, glucose and ketone bodies enzymatic analysis. ATP was also assayed in kidney samples. RESULTS: Lactacemia and ketonemia were significantly increased in Ala-Gln treated rats during reperfusion. Kidney pyruvate concentrations were significantly decreased and tissue lactate concentrations were significantly increased during reperfusion (1h and 3h in G-2 rats compared with respective controls. Glucose, ATP and ketone bodies concentrations were significantly increased in the kidney in L-Ala-Gln treated rats at 3 hours after reperfusion as compared to respective controls. CONCLUSIONS: Unilateral hind limb ischemia in L-Ala-Gln pre-treated rats may induce increased lactacemia and increased kidney lactate concentrations, indicating increased glycolytic activity in renal medulla and in other peripheral tissues. Higher ketonemia during reperfusion may reflect a possible increase in ketogenesis due to lower insulin plasma concentration hepatic signaling as a result of increased glucose oxidation in peripheral tissues, caused by the intra-gastric administration of glutamine dipeptide, suggesting also decreased insulin resistance.OBJETIVO: Investigar alterações dos parâmetros metabólicos no sangue e rim de ratos submetidos à isquemia/reperfusão do membro pélvico. MÉTODOS: Quarenta e oito

  4. 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;


    in normotensive subjects. Neither does it affect CO2 reactivity. The uniform results obtained with the two methods suggest TCD as a usable alternative to conventional CBF technique in the assessment of cerebral vasoactivity of various drugs in subjects with a normal cerebral circulation.......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...

  5. Blood flows and metabolic components of the cardiome. (United States)

    Bassingthwaighte, J B; Li, Z; Qian, H


    This is a plan for the first stage of The Cardiome Project. The cardiome is the representation, in quantitative, testable form, of the functioning of the normal heart and its responses to intervention. The goal is to integrate the efforts of many years into a comprehensive understandable scheme. Past efforts have spanned the fields of transport within blood vessels, the distributions of regional coronary blood flows, permeation processes through capillary and cell walls, mediated cell membrane transport, extra- and intracellular diffusion, cardiac electrophysiology, the uptake and metabolism of the prime substrates (fatty acid and glucose), the metabolism of the purine nucleosides and nucleotides (mainly adenosine and ATP), the regulation of the ionic currents and of excitation-contraction coupling and finally the regulation of contraction. The central theme is to define the coronary flows and metabolic components of a computer model that will become a part of a three-dimensional heart with appropriate fibre shortening and volume ejection. The components are: (a) coronary flow distributions with appropriate heterogeneity, (b) metabolism of the substrates for energy production, (c) ATP, PCr and energy metabolism and (d) calcium metabolism as it relates to excitation-contraction coupling. The modeling should provide: (1) appropriate responses to regional ischemia induced by constriction of a coronary artery, including tissue contractility loss and aneurysmal dilation of the ischemic region; (2) physiological responses to rate changes such as treppe and changes in metabolic demand and (3) changes in local metabolic needs secondary to changes in the site of pacing stimulation and shortening inactivation or stretch activation of contraction.

  6. Topical hepatic hypothermia plus ischemic preconditioning: analysis of bile flow and ischemic injuries after initial reperfusion in rats Hipotermia hepática tópica mais pré-condicionamento isquêmico: análise do fluxo biliar e danos isquêmicos após a reperfusão inicial em ratos

    Directory of Open Access Journals (Sweden)

    Tomaz de Jesus Maria Grezzana Filho


    Full Text Available PURPOSE: To evaluate the effects of the topical liver hypothermia and IPC combination against I/R injury after initial reperfusion. METHODS: In 32 Wistar rats, partial liver ischemia was induced for 90 minutes in normothermia (IN, ischemic preconditioning (IPC, 26ºC topical hypothermia (H and 26ºC topical hypothermia plus IPC (H+IPC. MAP, body temperature and bile flow were recorded each 15 minutes. Plasmatic injury markers and tissue antioxidant defenses were assessed after 120 minutes of reperfusion. RESULTS: MAP and body temperature remained constant during all experiment. Bile flow returned to levels similar to controls after 45 minutes of reperfusion in the H and H+IPC groups and increased significantly in comparison to the NI and IPC groups after 105 and 120 minutes. AST and ALT increased significantly in the normothermic groups in comparison to controls. TBARS levels decreased significantly in the H+IPC group in comparison to the other groups whereas Catalase levels increased significantly in the IPC group. SOD levels were significantly higher in the H group in comparison to all groups. CONCLUSION: The induction of 26ºC topical hypothermia associated or not to IPC protected the ischemic liver against ischemia/reperfusion injuries and allowed an early recovery of the hepatic function.OBJETIVO: Avaliar os efeitos da hipotermia hepática tópica combinada ao pré-condicionamento isquêmico na proteção dos danos iniciais de isquemia e reperfusão. MÉTODOS: Trinta e dois ratos Wistar foram submetidos à isquemia hepática parcial durante 90 minutos em Normotermia (IN, Pré-condicionamento Isquêmico (IPC, Hipotermia a 26ºC (H e Hipotermia a 26ºC mais PCI (H+PCI. A PAM, a temperatura corporal e o fluxo biliar foram aferidos em intervalos de 15 minutos. Marcadores plasmáticos de danos hepáticos e as defesas antioxidantes foram avaliados após 120 minutos de reperfusão. RESULTADOS: A PAM e a temperatura corporal permaneceram constantes

  7. Quantitative photoacoustic assessment of red blood cell aggregation under pulsatile blood flow: experimental and theoretical approaches (United States)

    Bok, Tae-Hoon; Hysi, Eno; Kolios, Michael C.


    In the present paper, the optical wavelength dependence on the photoacoustic (PA) assessment of the pulsatile blood flow was investigated by means of the experimental and theoretical approaches analyzing PA radiofrequency spectral parameters such as the spectral slope (SS) and mid-band fit (MBF). For the experimental approach, the pulsatile flow of human whole blood at 60 bpm was imaged using the VevoLAZR system (40-MHz-linear-array probe, 700-900 nm illuminations). For the theoretical approach, a Monte Carlo simulation for the light transmit into a layered tissue phantom and a Green's function based method for the PA wave generation was implemented for illumination wavelengths of 700, 750, 800, 850 and 900 nm. The SS and MBF for the experimental results were compared to theoretical ones as a function of the illumination wavelength. The MBF increased with the optical wavelength in both theory and experiments. This was expected because the MBF is representative of the PA magnitude, and the PA signal from red blood cell (RBC) is dependent on the molar extinction coefficient of oxyhemoglobin. On the other hand, the SS decreased with the wavelength, even though the RBC size (absorber size which is related to the SS) cannot depend on the illumination wavelength. This conflicting result can be interpreted by means of the changes of the fluence pattern for different illumination wavelengths. The SS decrease with the increasing illumination wavelength should be further investigated.

  8. Absolute counting of neutrophils in whole blood using flow cytometry. (United States)

    Brunck, Marion E G; Andersen, Stacey B; Timmins, Nicholas E; Osborne, Geoffrey W; Nielsen, Lars K


    Absolute neutrophil count (ANC) is used clinically to monitor physiological dysfunctions such as myelosuppression or infection. In the research laboratory, ANC is a valuable measure to monitor the evolution of a wide range of disease states in disease models. Flow cytometry (FCM) is a fast, widely used approach to confidently identify thousands of cells within minutes. FCM can be optimised for absolute counting using spiked-in beads or by measuring the sample volume analysed. Here we combine the 1A8 antibody, specific for the mouse granulocyte protein Ly6G, with flow cytometric counting in straightforward FCM assays for mouse ANC, easily implementable in the research laboratory. Volumetric and Trucount™ bead assays were optimized for mouse neutrophils, and ANC values obtained with these protocols were compared to ANC measured by a dual-platform assay using the Orphee Mythic 18 veterinary haematology analyser. The single platform assays were more precise with decreased intra-assay variability compared with ANC obtained using the dual protocol. Defining ANC based on Ly6G expression produces a 15% higher estimate than the dual protocol. Allowing for this difference in ANC definition, the flow cytometry counting assays using Ly6G can be used reliably in the research laboratory to quantify mouse ANC from a small volume of blood. We demonstrate the utility of the volumetric protocol in a time-course study of chemotherapy induced neutropenia using four drug regimens.

  9. Theory to predict shear stress on cells in turbulent blood flow. (United States)

    Morshed, Khandakar Niaz; Bark, David; Forleo, Marcio; Dasi, Lakshmi Prasad


    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.

  10. A simple model of cerebral blood flow dependence on arterial blood pressure

    CERN Document Server

    Gersten, Alexander


    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. 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;


    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

  12. Outcome of splanchnic blood flow determination in patients with suspected chronic intestinal ischaemia. A retrospective survey

    DEFF Research Database (Denmark)

    Møller, Søren; Madsen, Jan Lysgård


    flow: A, normal response (splanchnic blood flow > or = 200 ml/min); B, possible abnormal response (splanchnic blood flow 51-199 ml/min); and C, definitive abnormal response (splanchnic blood flow place, the type of operation was noted. RESULTS: Forty patients had...... a normal meal-induced response, 23 patients had a possible abnormal response and 10 patients had a definitive abnormal response, which gave evidence of chronic intestinal ischaemia. In the total patient population, the increase in splanchnic blood flow was significantly correlated to an increase in hepatic...

  13. Glucagon-like peptide-2 increases mesenteric blood flow in humans

    DEFF Research Database (Denmark)

    Bremholm, Lasse; Hornum, Mads; Henriksen, Birthe Merete;


    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...... were measured by Doppler ultrasound scanning of the superior mesenteric artery (SMA). The aim of the study was to demonstrate the influence of GLP-2 on this flow, expressed as changes in resistance index (RI). MATERIAL AND METHODS: A homogeneous group of 10 fasting healthy volunteers completed a 2-day...... support the hypothesis that GLP-2 is an important regulator of mesenteric blood flow....

  14. Sympathetic reflex control of subcutaneous blood flow in tetraplegic man during postural changes

    DEFF Research Database (Denmark)

    Skagen, K; Jensen, K; Henriksen, O


    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...

  15. Dynamic Modeling of Renal Blood Flow in Dahl Hypertensive and Normotensive Rats

    DEFF Research Database (Denmark)

    Knudsen, Torben; Elmer, H.; Knudsen, Morten;


    A method is proposed in this paper which allows characterisation of renal autoregulatory dynamics and efficiency using quantitative mathematical methods. Based on data from rat experiments, where arterial blood pressure and renal blood flow are measured, a quantitative model for renal blood flow ...

  16. An approach to automatic blood vessel image registration of microcirculation for blood flow analysis on nude mice. (United States)

    Lin, Wen-Chen; Wu, Chih-Chieh; Zhang, Geoffrey; Wu, Tung-Hsin; Lin, Yang-Hsien; Huang, Tzung-Chi; Liu, Ren-Shyan; Lin, Kang-Ping


    Image registration is often a required and a time-consuming step in blood flow analysis of large microscopic video sequences in vivo. In order to obtain stable images for blood flow analysis, frame-to-frame image matching as a preprocessing step is a solution to the problem of movement during image acquisition. In this paper, microscopic system analysis without fluorescent labelling is performed to provide precise and continuous quantitative data of blood flow rate in individual microvessels of nude mice. The performance properties of several matching metrics are evaluated through simulated image registrations. An automatic image registration programme based on Powell's optimisation search method with low calculation redundancy was implemented. The matching method by variance of ratio is computationally efficient and improves the registration robustness and accuracy in practical application of microcirculation registration. The presented registration method shows acceptable results in close requisition to analyse red blood cell velocities, confirming the scientific potential of the system in blood flow analysis.

  17. 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;


    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....

  18. Cell-cell interaction in blood flow in patients with coronary heart disease (in vitro study) (United States)

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


    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.

  19. 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


    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

  20. Coagulation on biomaterials in flowing blood: some theoretical considerations. (United States)

    Basmadjian, D; Sefton, M V; Baldwin, S A


    Are truly inert biomaterials feasible? Recent mathematical models of coagulation which are reviewed here suggest that such materials are impossible. This conclusion, which is certainly consistent with our collective experimental evidence, arises from the calculation that conversion of Factor XI to XIa never drops to zero even at the highest flow rates and with virtually no Factor XIIa bound to a surface. Residual amounts of XIa are still formed which can in principle kick-off the coagulation cascade. Furthermore, if the flow rates and corresponding mass transfer coefficients are low and in spite of these near-vanishing levels of the initiating coagulants, the surprising result is that substantial amounts of thrombin are produced. On the contrary, under slightly higher flow conditions, there can be more substantial levels of initiating coagulants, yet paradoxically thrombin production is near zero. This article presents a theoretical understanding of the events which take place during the interaction of biomaterials with flowing blood. We follow these events from the time of first contact to the final production of thrombin. The effect of flow and surface activity on the contact phase reactions is examined in detail and the two are found to be intertwined. The common pathway is also examined and here the main feature is the existence of three flow dependent regions which produce either high or very low levels of thrombin, as well as multiple thrombin steady states. In a final analysis we link the two segments of the cascade and consider the events which result. In addition, we note that multiple steady states arise only in the presence of two (thrombin) feedback loops. Single loops or the bare cascade will produce only single steady states. With some imagination one can attribute to the feedback loops the role of providing the cascade with a mechanism to produce high thrombin levels in case of acute need (e.g. bleeding) or to allow levels to subside to 'stand

  1. Detection of viable cortical neurons using benzodiazepine receptor imaging after reversible focal ischaemia in rats: comparison with regional cerebral blood flow

    Energy Technology Data Exchange (ETDEWEB)

    Watanabe, Yoshiyuki [Dept. of Radiology, Osaka National Hospital (Japan); Nakano, Takayuki; Yutani, Kenji; Nishimura, Hiroshi; Nishimura, Tsunehiko [Div. of Tracer Kinetics, Osaka University Medical School (Japan); Kusuoka, Hideo [Clinical Research Institute, Osaka National Hospital (Japan); Nakamura, Hironobu [Dept. of Radiology, Osaka University Medical School (Japan)


    To elucidate the utility of benzodiazepine receptor imaging for the detection of viable cortical neurons, dual-tracer autoradiography using iodine-125 iomazenil (IMZ) and iodine-123 N-isopropyl-4-iodoamphetamine (IMP) was performed in a model of reversible focal ischaemia during the acute and subacute phases. The right middle cerebral artery of anaesthetized rats was occluded for 60 min using an intraluminal filament and reperfused. In the acute phase study, {sup 125}I-IMZ (370 kBq) was injected via the femoral vein at 2 h after reperfusion, and {sup 123}I-IMP (37 MBq) was injected at 50 min post-injection. Rats were sacrificed 10 min after the injection of {sup 123}I-IMP. In the subacute phase study, the same procedure was performed at 5 days after reperfusion. In the acute phase, the IMP uptake was significantly decreased in almost all areas of the lesioned hemisphere, an exception being the cerebellum; however, the IMZ uptake was significantly decreased only in ischaemic cores. The discrepancy between IMZ and IMP uptake was observed in the lateral neocortex and the lateral caudate putamen (CPu), which were most frequently damaged in this ischaemic model. In the subacute phase, the IMZ uptake in lesioned rats was significantly decreased only in the parietal lobe and hippocampus, though the IMP uptake was decreased in many regions of lesioned hemispheres (the frontal, parietal cortex, CPu, hippocampus and thalamus). Histopathological findings indicated that both the IMP and the IMZ uptake was markedly decreased in necrotic areas. Although the IMP uptake was significantly decreased in the ischaemic areas, the IMZ uptake was maintained in these areas. These results suggest that benzodiazepine receptor imaging is superior to regional cerebral blood flow imaging for the detection of viable cortical neurons in both the acute and subacute phases of ischaemia. (orig.)

  2. Coded Ultrasound for Blood Flow Estimation Using Subband Processing

    DEFF Research Database (Denmark)

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


    the excitation signal is broadband and has good spatial resolution after pulse compression. This means that time can be saved by using the same data for B-mode imaging and blood flow estimation. Two different coding schemes are used in this paper, Barker codes and Golay codes. The performance of the codes...... signals are used to increase SNR, followed by subband processing. The received broadband signal is filtered using a set of narrow-band filters. Estimating the velocity in each of the bands and averaging the results yields better performance compared with what would be possible when transmitting a narrow......-band pulse directly. Also, the spatial resolution of the narrow-band pulse would be too poor for brightness-mode (B-mode) imaging, and additional transmissions would be required to update the B-mode image. For the described approach in the paper, there is no need for additional transmissions, because...

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

    CERN Document Server

    Thiriet, Marc


    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...

  4. Numerical method of characteristics for one-dimensional blood flow

    CERN Document Server

    Acosta, Sebastian; Riviere, Beatrice; Penny, Daniel J; Rusin, Craig G


    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 ...

  5. Laser Doppler flowmetry to measure changes in cerebral blood flow. (United States)

    Sutherland, Brad A; Rabie, Tamer; Buchan, Alastair M


    Laser Doppler flowmetry (LDF) is a method by which relative cerebral blood flow (CBF) of the cortex can be measured. Although the method is easy to employ, LDF only measures relative CBF, while absolute CBF cannot be quantified. LDF is useful for investigating CBF changes in a number of different applications including neurovascular and stroke research. This chapter will prepare the reader for rodent experiments using LDF with two preparations. The closed skull preparation can be used to monitor CBF with an intact skull, but in adult rats, thinning of the skull is required to obtain an accurate cortical CBF signal. The open skull preparation requires a craniotomy to expose the surface of the brain and the LDF probe is held close to the surface to measure cerebral perfusion.

  6. Tomographic non-invasive measurements of regional cerebral blood flow

    Energy Technology Data Exchange (ETDEWEB)

    Hedde, J.P.; Reischies, W.; Fiegler, R.; Felix, H.; Helmchen, H.; Kanowski, S.


    The measurement of the regional cerebral blood flow by means of the dynamic single-photon-emission-computed tomography is a method of examination which is completely free of risk for the patient, causes no inconvenience and can be repeated whenever it seems necessary. This method gives a quantitative explanation for the distribution of the effective cerebral perfusion and can only be substituted by the very complicated positron-emission-computed tomography. As well as the exact assessment of the hemodynamic relevance of cerebral vascular disease, this method enables us to prove whether or not in various types of psychiatric disorders an interference in the regional perfusion exists. This method can also contribute to the clarification of pathogenic mechanisms, as well as to the nosological classification of specific psychopathological conditions.

  7. Peculiarities of Brain's Blood Flow : Role of Carbon Dioxide

    CERN Document Server

    Gersten, Alexander


    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.

  8. 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))


    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).

  9. Repeated blood flow restriction induces muscle fiber hypertrophy. (United States)

    Sudo, Mizuki; Ando, Soichi; Kano, Yutaka


    We recently developed an animal model to investigate the effects of eccentric contraction (ECC) and blood flow restriction (BFR) on muscle tissue at the cellular level. This study clarified the effects of repeated BFR, ECC, and BFR combined with ECC (BFR+ECC) on muscle fiber hypertrophy. Male Wistar rats were assigned to 3 groups: BFR, ECC, and BFR+ECC. The contralateral leg in the BFR group served as a control (CONT). Muscle fiber cross-sectional area (CSA) of the tibialis anterior was determined after the respective treatments for 6 weeks. CSA was greater in the BFR+ECC group than in the CONT (P muscle fiber hypertrophy at the cellular level. Muscle Nerve 55: 274-276, 2017. © 2016 Wiley Periodicals, Inc.

  10. Regulation of the skeletal muscle blood flow in humans

    DEFF Research Database (Denmark)

    Mortensen, Stefan; Saltin, Bengt


    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...... and endothelial cells. In the interstitium, both ATP and adenosine stimulate the formation of NO and prostaglandins, but ATP has also been suggested to induce vasoconstriction and stimulate afferent nerves that signal to increase sympathetic nerve activity. Adenosine has been shown to contribute to exercise...

  11. A dynamic model of renal blood flow autoregulation

    DEFF Research Database (Denmark)

    Holstein-Rathlou, N H; Marsh, D J


    To test whether a mathematical model combining dynamic models of the tubuloglomerular feedback (TGF) mechanism and the myogenic mechanism was sufficient to explain dynamic autoregulation of renal blood flow, we compared model simulations with experimental data. To assess the dynamic characteristics...... nephrons act in parallel, each simulation was performed with 125 parallel versions of the model. The key parameters of the 125 versions of the model were chosen randomly within the physiological range. None of the constituent models, i.e., the TGF and the myogenic, could alone reproduce the experimental...... observations. However, in combination they reproduced most of hte features of the various transfer functions calculated from the experimental data. The major discrepancy was the presence of a bimodal distribution of the admittance phase in the simulations. This is not consistent with most of the experimental...

  12. Caring for patients with lesions increasing pulmonary blood flow. (United States)

    Moynihan, P J; King, R


    The most common congenital cardiac defect is VSD. This malady accounts for 20 to 30 per cent of all congenital cardiac defects and is representative of a cardiac lesion that increases pulmonary blood flow. Although lesions, which increase pulmonary blood flow, may vary in incidence, they frequently have common symptomatology. Over time, congestive heart failure becomes a problem. Poor respiratory status leads to weight loss, poor feeding, and failure to thrive. If unrepaired, the child often presents with cyanosis and tachypnea. The history may include frequent respiratory infections, exercise intolerance, generalized malaise, or fatigue. In spite of poor weight gain, the child may be edematous and have a large liver. Definitive diagnosis of each lesion may be made by echocardiogram, cardiac catheterization, or both. With these data and a detailed history, treatment and management decisions are determined. In most cases, as the child gets older, symptoms become more evident. This is the result of high pulmonary pressure. High pressure over time causes a thickening of the alveolar tissue, which decreases the permeability of the alveolar membranes for gas exchange. Lung changes can become irreversible, but it is unusual for irreversible changes to occur before 1 year of age. All the lesions described in this article are amendable to primary repair before 1 year of age, affording the best functional results. Postoperative nursing care includes management of persisting CHF and PVR while maintaining adequate cardiac output. Many factors, including electrolyte balance, nutritional status, conduction disturbances, stress, and parental anxiety, influence the management of these infants. The outcome depends greatly on the assessment skill of a highly competent cardiac intensive care nurse and an environment conducive to collaborative practice.

  13. Doppler Assessment of Uterine Blood Flow in Recurrent Pregnancy Loss

    Directory of Open Access Journals (Sweden)

    Maryam Barzin


    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

  14. Nitric oxide and prostaglandins influence local skeletal muscle blood flow during exercise in humans: coupling between local substrate uptake and blood flow

    DEFF Research Database (Denmark)

    Kalliokoski, Kari K; Langberg, Henning; Ryberg, Ann Kathrine;


    skeletal muscle. Skeletal muscle blood flow was measured in seven healthy young men using near-infrared spectroscopy and indocyanine green and muscle glucose uptake using positron emission tomography and 2-fluoro-2-deoxy-D-[(18)F]glucose without and with local blockade of NO and PG at rest and during one-legged...... dynamic knee-extension exercise. Local blockade was produced by infusing nitro-L-arginine methyl ester and indomethacin directly in the muscle via a microdialysis catheter. Blood flow and glucose uptake were measured in the region of blockade and in two additional regions of vastus lateralis muscle 1......Synergic action of nitric oxide (NO) and prostaglandins (PG) in the regulation of muscle blood flow during exercise has been demonstrated. In the present study, we investigated whether these vasodilators also regulate local blood flow, flow heterogeneity, and glucose uptake within the exercising...

  15. Role of cerebral blood flow in extreme breath holding

    Directory of Open Access Journals (Sweden)

    Bain Anthony R.


    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.

  16. Subcutaneous blood flow in the temporal region of migraine patients

    Energy Technology Data Exchange (ETDEWEB)

    Jensen, K.


    Subcutaneous blood flow in the temporal region (TSBF) was measured by the local 133 Xenon washout technique in 43 migraine patients; 19 were reexamined in the course of spontaneous attacks. During attacks, TSBF was normal compared to headache-free state. In 13 unilateral attacks, the median ipsilateral to contralateral ratio TSBF was 1: 1.276, (NS). During 30 deg C passive head-up tilt, TSBF descreased by a median of 27% during headache-free intervals and by a median, 21% during migraine attacks. The difference between the 2 occasions was not significant. Head-up tilt resulted in a median 4.5% increase in mean arterial blood pressure (MAP) and a median 5.3% increase in heart rate (HR) during headache-free intervals and 3.4% and 3.2% respectively during migraine attacks. These results are evidence against a vasomotor disturbance of the extracranial tissues during attacks of migraine. The cardio-vascular response to the orthostatic stimulus indicates a normal function of this part of the autonomic nervous system during migraine attacks.


    Directory of Open Access Journals (Sweden)

    Alan Kacin


    Full Text Available Blood flow restricted resistance (BFRR training with pneumatic tourniquet has been suggested as an alternative for conventional weight training due to the proven benefits for muscle strength and hypertrophy using relatively low resistance, hence reducing the mechanical stress across a joint. As such, it has become an important part of rehabilitation programs used in either injured or operated athletes. Despite a general consensus on effectiveness of BFRR training for muscle conditioning, there are several uncertainties regarding the interplay of various extrinsic and intrinsic factors on its safety and efficiency, which are being reviewed from a clinical perspective. Among extrinsic factors tourniquet cuff pressure, size and shape have been identified as key for safety and efficiency. Among intrinsic factors, limb anthropometrics, patient history and presence of cardiac, vascular, metabolic or peripheral neurologic conditions have been recognized as most important. Though there are a few potential safety concerns connected to BFRR training, the following have been identified as the most probable and health-hazardous: (a mechanical injury to the skin, muscle, and peripheral nerves, (b venous thrombosis due to vascular damage and disturbed hemodynamics and (c augmented arterial blood pressure responses due to combined high body exertion and increased peripheral vascular resistance. Based on reviewed literature and authors’ personal experience with the use of BFRR training in injured athletes, some guidelines for its safe application are outlined. Also, a comprehensive risk assessment tool for screening of subjects prior to their inclusion in a BFRR training program is being introduced.

  18. Cerebral blood flow during static exercise in humans

    DEFF Research Database (Denmark)

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


    voluntary contraction (MVC) and utilized alternate legs. CBF (measured by the 133Xe clearance technique) was expressed by a noncompartmental flow index (ISI). Heart rate and mean arterial pressure increased from resting values of 73 (55-80) beats/min and 88 (74-104) mmHg to 106 (86-138) beats/min and 124......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 maximal...... resistance increased from 1.5 (1.0-2.2) to 2.4 (1.4-3.0) mmHg. 100 (P less than 0.025) at 32% of MVC. There was no difference in CBF between the two hemispheres at rest or during exercise. In contrast to dynamic leg exercise, static leg exercise is not associated with an increase in global CBF...

  19. Physiological non-Newtonian blood flow through single stenosed artery (United States)

    Mamun, Khairuzzaman; Rahman, Mohammad Matiur; Akhter, Most. Nasrin; Ali, Mohammad


    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.

  20. Airway blood flow response to dry air hyperventilation in sheep

    Energy Technology Data Exchange (ETDEWEB)

    Parsons, G.H.; Baile, E.M.; Pare, P.D.


    Airway blood flow (Qaw) may be important in conditioning inspired air. To determine the effect of eucapneic dry air hyperventilation (hv) on Qaw in sheep the authors studied 7 anesthetized open-chest sheep after 25 min. of warm dry air hv. During each period of hv the authors have recorded vascular pressures, cardiac output (CO), and tracheal mucosal and inspired air temperature. Using a modification of the reference flow technique radiolabelled microspheres were injected into the left atrium to make separate measurements after humid air and dry air hv. In 4 animals a snare around the left main pulmonary artery was used following microsphere injection to prevent recirculation (entry into L lung of microspheres from the pulmonary artery). Qaw to the trachea and L lung as measured and Qaw for the R lung was estimated. After the final injection the sheep were killed and bronchi (Br) and lungs removed. Qaw (trachea plus L lung plus R lung) in 4 sheep increased from a mean of 30.8 to 67.0 ml/min. Airway mucosal temp. decreased from 39/sup 0/ to 33/sup 0/C. The authors conclude that dry air hv cools airway mucosa and increases Qaw in sheep.

  1. A Method for Gray-Scale Imaging of Blood Flow Using High-Frequency Ultrasound. (United States)

    Yang, Jun; Pang, Chao; Song, Xue-Dong; Gao, Xuan


    This paper presents a new method that complements current techniques available in the high-frequency blood imaging field. A comprehensive scattering model was established to determine the feasibility and frequency range of the blood flow imaging of superficial organs and tissues using high-frequency ultrasound. The transmitting and receiving modes and an algorithm were designed to obtain blood flow information based on differentiation between tissues and blood flow. The system was created and tested first with a model that simulates blood flow and was then used on human tissue. A fine-scale image of a blood vessel could be obtained with this system. Moreover, this method can obtain weak blood flow signal using single pulse rather than the traditional pulse-code method and maintains a high resolution that can be matched to high-frequency structural imaging. This study provides a reliable method for further applications related to diagnoses of superficial organs.

  2. Skeletal blood flow in Paget's disease of bone and its response to calcitonin therapy. (United States)

    Wootton, R; Reeve, J; Spellacy, E; Tellez-Yudilevich, M


    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.

  3. Timing and topography of cerebral blood flow, aura, and headache during migraine attacks

    DEFF Research Database (Denmark)

    Olesen, J; Friberg, L; Olsen, T S


    and statistically significant spatial relations. The first observable event was a decrease of regional cerebral blood flow posteriorly in one cerebral hemisphere. Further development of this pathological process was accompanied by the aura symptoms. Thereafter headache occurred while regional cerebral blood flow...... remained decreased. During the headache phase, regional cerebral blood flow gradually changed from abnormally low to abnormally high without apparent change in headache. In some patients headache disappeared while regional cerebral blood flow remained increased. Although regional cerebral blood flow...... reduction and aura symptoms in the great majority of patients were unilateral, one-third had bilateral headache. Unilateral headache usually localized to the side on which regional cerebral blood flow was reduced and from which the aura symptoms originated (i.e., aura symptoms were perceived to occur...

  4. Limb blood flow - Rest and heavy exercise in sitting and supine positions in man (United States)

    Greenleaf, J. E.; Montgomery, L. D.; Brock, P. J.; Van Beaumont, W.


    The objectives of the study were twofold: (1) to determine the effect of body position (hydrostatic pressure) on total blood flow in active and passive limbs at rest and after severe exercise; and (2) to further evaluate the impedance technique for measurement of blood flow. To this end, the effect of body position on the redistribution of total blood flow in active (leg) and passive (forearm) limbs during exercise was determined by measuring total limb impedance (blood flow) in five male and one female subjects in sitting and supine positions with a modified Beckman BR-100 rheograph. The results show that, at rest and after exercise, the supine position induces significantly greater flows in the leg but not in the forearm. With severe exercise, blood flows are increased in both passive and active limbs, so that there is probably no net transfer of blood volume from passive to active muscles. The advantages of the impedance technique over other methods are stressed.

  5. 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;


    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...

  6. Subcutaneous blood flow in man during sleep with continous epdural anaesthesia

    DEFF Research Database (Denmark)

    Sindrup, JH; Petersen, Lars Jelstrup; Kastrup, Jens;


    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...

  7. The protecting effects and mechanism of betaine hydrochloride on hepatic ischemia-reperfusion injury in rats

    Institute of Scientific and Technical Information of China (English)

    XIN Xiao-ming; MA Lian-long; GAO Yong-feng; WANG Hao; WANG Xiao-dan; ZHU Yu-yun; GAO Yun-sheng


    Objective To study the protecting effects and mechanism of betaine hydrochloride on hepatic ischemia-reperfusion injury in rats. Methods Fourty SD rats were randomly divided into 5 groups (8 animals in each group) : sham-operated control group (A), hepatic ischemia-reperfusion group (B), 200 mg·kg-1 400 mg·kg-1 800 mg·kg-1 betaine hydrochloride + hepatic ischemia-reperfusion group (C、D、E). betaine hydrochloride was administered to animals byoral route in group C、D、E for 7 days before ischemia. A、B group was administered with NS. Made the animal model of part hepatic ischemia-reperfusion. Serum alanine aminotransferase (ALT), aspartate aminotransferase (AST) levels in the blood and themalondialdehyde (MDA), superoxide dismutase (SOD), protein content in hepatic tissue were determined after the liver had been reperfused for 24 hours; the hepatic tissue was examined under lightmieroscope and the cell apoptosis was demonstrated with flow cytometry. Results ALT, AST, MDA increased and SOD decreased significantly in B group when compared those in the A group (P<0.05), Hepatic apoptosis was significantly increased; ALT, AST, MDA decreased and SOD increased significantly in betaine hydrochloride 200 mg·kg-1(C) group when compared those in the B group(P<0.05). Hepatic apoptosis was significantly lower, The histologic changes of the liver tissue under lightmicroscope in the C group was more easer than in the I/R group (B). Conclusions Betaine hydrochloride has the ability to scavenge oxygen free radical (OFR), reduce lipid peroxidation and inhibition of apoptosis. So it can protect the rats liver damaged by ischemia-reperfusion.

  8. Incidental Cerebral Microbleeds and Cerebral Blood Flow in Elderly Individuals. (United States)

    Gregg, Nicholas M; Kim, Albert E; Gurol, M Edip; Lopez, Oscar L; Aizenstein, Howard J; Price, Julie C; Mathis, Chester A; James, Jeffrey A; Snitz, Beth E; Cohen, Ann D; Kamboh, M Ilyas; Minhas, Davneet; Weissfeld, Lisa A; Tamburo, Erica L; Klunk, William E


    Cerebral microbleeds (CMBs) are collections of blood breakdown products that are a common incidental finding in magnetic resonance imaging of elderly individuals. Cerebral microbleeds are associated with cognitive deficits, but the mechanism is unclear. Studies show that individuals with CMBs related to symptomatic cerebral amyloid angiopathy have abnormal vascular reactivity and cerebral blood flow (CBF), but, to our knowledge, abnormalities in cerebral blood flow have not been reported for healthy individuals with incidental CMBs. To evaluate the association of incidental CMBs with resting-state CBF, cerebral metabolism, cerebrovascular disease, β-amyloid (Aβ), and cognition. A cross-sectional study of 55 cognitively normal individuals with a mean (SD) age of 86.8 (2.7) years was conducted from May 1, 2010, to May 1, 2013, in an academic medical center in Pittsburgh; data analysis was performed between June 10, 2013, and April 9, 2015. 3-Tesla magnetic resonance imaging was performed with susceptibility-weighted imaging or gradient-recalled echo to assess CMBs, arterial spin labeling for CBF, and T1- and T2-weighted imaging for atrophy, white matter hyperintensities, and infarcts. Positron emission tomography was conducted with fluorodeoxyglucose to measure cerebral metabolism and Pittsburgh compound B for fibrillar Aβ. Neuropsychological evaluation, including the Clinical Dementia Rating scale, was performed. Magnetic resonance images were rated for the presence and location of CMBs. Lobar CMBs were subclassified as cortical or subcortical. Measurements of CBF, metabolism, and Aβ were compared with the presence and number of CMBs with voxelwise and region-of-interest analyses. The presence of cortical CMBs was associated with significantly reduced CBF in multiple regions on voxelwise and region-of-interest analyses (percentage difference in global CBF, -25.3%; P = .0003), with the largest reductions in the parietal cortex (-37.6%; P CMBs showed a

  9. The protective effect of niacinamide on ischemia-reperfusion-induced liver injury. (United States)

    Chen, C F; Wang, D; Hwang, C P; Liu, H W; Wei, J; Lee, R P; Chen, H I


    Reperfusion of ischemic liver results in the generation of oxygen radicals, nitric oxide (NO) and their reaction product peroxynitrite, all of which may cause strand breaks in DNA, which activate the nuclear enzyme poly(ADP ribose)synthase (PARS). This results in rapid depletion of intracellular nicotinamide adenine dinucleotide and adenosine 5'-triphosphate (ATP) and eventually induces irreversible cytotoxicity. In this study, we demonstrated that niacinamide, a PARS inhibitor, attenuated ischemia/reperfusion (I/R)-induced liver injury. Ischemia was induced by clamping the common hepatic artery and portal vein of rats for 40 min. Thereafter, flow was restored and the liver was reperfused for 90 min. Blood samples collected prior to I and after R were analyzed for methyl guanidine (MG), NO, tumor necrosis factor (TNF-alpha) and ATP. Blood levels of aspartate transferase (AST), alanine transferase (ALT) and lactate dehydrogenase (LDH) which served as indexes of liver injury were measured. This protocol resulted in elevation of the blood NO level (p niacinamide (10 mM), liver injury was significantly attenuated, while blood ATP content was reversed. In addition, MG, TNF-alpha and NO release was attenuated. These results indicate that niacinamide, presumably by acting with multiple functions, exerts potent anti-inflammatory effects in I/R-induced liver injury.

  10. Chronic intestinal ischaemia: measurement of the total splanchnic blood flow. (United States)

    Zacho, Helle D


    A redundant collateral network between the intestinal arteries is present at all times. In case of ischaemia in the gastrointestinal tract, the collateral blood supply can develop further, thus accommodating the demand for oxygen even in the presence of significant stenosis or occlusion of the intestinal arteries without clinical symptoms of intestinal ischaemia. Symptoms of ischemia develop when the genuine and collateral blood supply no longer can accommodate the need for oxygen. Atherosclerosis is the most common cause of obliteration in the intestinal arteries. In chronic intestinal ischaemia (CII), the fasting splanchnic blood flow (SBF) is sufficient, but the postprandial increase in SBF is inadequate and abdominal pain will therefore develop in relation to food intake causing the patient to eat smaller meals at larger intervals with a resulting weight loss. Traditionally, the CII-diagnosis has exclusively been based upon morphology (angiography) of the intestinal arteries; however, substantial discrepancies between CII-symptoms and the presence of atherosclerosis/stenosis in the intestinal arteries have been described repeatedly in the literature impeding the diagnosis of CII. This PhD thesis explores a method to determine the total SBF and its potential use as a diagnostic tool in patients suspected to suffer from CII. The SBF can be measured using a continuous infusion of a tracer and catheterisation of a hepatic vein and an artery. By measuring the SBF before and after a standard meal it is possible to assess the ability or inability to enhance the SBF and thereby diagnosing CII. In Study I, measurement of SBF was tested against angiography in a group of patients suspected to suffer from CII due to pain and weight loss. A very good agreement between the postprandial increase in SBF and angiography was found. The method was validated against a well-established method independent of the hepatic extraction of tracer using pAH in a porcine model (study II

  11. Multiscale modeling of red blood cell mechanics and blood flow in malaria.

    Directory of Open Access Journals (Sweden)

    Dmitry A Fedosov


    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.

  12. Skin and muscle components of forearm blood flow in directly heated resting man. (United States)

    Detry, J.-M. R.; Brengelmann, G. L.; Rowell, L. B.; Wyss, C.


    Changes in forearm muscle blood flow (FMBF) during direct whole-body heating were measured in 17 normal subjects using three different methods. We conclude that FMBF is not increased by direct whole-body heating. Since renal and splanchnic blood flow fall 30% under these conditions, maximal total skin blood flow in 12 previously studied subjects can be estimated from the rise in cardiac output to be 7.6 L/min (3.0-11.1 L/min).

  13. The application of blood flow measurements to the study of aging muscle. (United States)

    McCully, K K; Posner, J D


    Blood flow to skeletal muscle is a potentially important factor in the reduction of muscle function associated with aging (sarcopenia). The main influence of reduced blood flow capacity on muscle function is in limiting oxidative metabolism. Direct measures of blood flow include: intravital-microscopy, plethysmography, radioactive microspheres, 133Xenon washout, thermodilution, and Doppler ultrasound. Indirect measurement of blood flow includes arm-to-ankle pressure index and the rate of phosphocreatine recovery after exercise. Several new methodologies have been developed to evaluate muscle blood flow, including color-Doppler imaging, magnetic resonance imaging/angiography (MRI/MRA), and near-infrared spectroscopy (NIRS). As adaptations of traditional techniques, these methods promise more precise information under less invasive conditions. MRI is an expensive and technically challenging method able to measure vessel location, blood flow, and wall diameter in blood vessels throughout the cardiac cycle. Color-Doppler provides excellent temporal resolution blood flow throughout the cardiac cycle, along with some anatomical information. NIRS is an inexpensive and portable technology that can measure changes in oxygen saturation and provide information on tissue oxygen delivery in studies of frailer and more difficult-to-study subjects. Muscle blood flow is not thought to limit oxidative metabolism under normal conditions in young individuals. However, it is not clear what happens to muscle blood flow in healthy older individuals. Reduced capillary density, less maximal blood flow, and a slower hyperemic flow response have been reported in some, but not all, studies. Further studies with the newer methodologies are needed to re-examine age-related changes in muscle blood flow.(ABSTRACT TRUNCATED AT 250 WORDS)

  14. Extraction of the magnetohydrodynamic blood flow potential from the surface electrocardiogram in magnetic resonance imaging. (United States)

    Nijm, Grace M; Swiryn, Steven; Larson, Andrew C; Sahakian, Alan V


    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.

  15. Feasibility of intercostal blood flow measurement by echo-Doppler technique in healthy subjects. (United States)

    de Bisschop, Claire; Montaudon, Michel; Glénet, Stéphane; Guénard, Hervé


    Intercostal artery blood flow supplies the external and internal intercostal muscles, which are inspiratory and expiratory muscles. Intercostal blood flow measured by the echo-Doppler (ED) technique has not previously been reported in humans. This study describes the feasibility of this measurement during free and loaded breathing in healthy subjects. Systolic, diastolic and mean blood flows were measured in the eighth dorsal intercostal space during free and loaded breathing using the ED technique. Flows were calculated as the product of the artery intraluminal surface and blood velocity. Ten healthy subjects (42 ± 13·6 years) were included. Integrated electromyogram (iEMG), arterial pressure, cardiac frequency and breathing pattern were also recorded. Mean blood flows were 3·5 ± 1·2 ml min(-1) at rest, 6 ± 2·6 ml min(-1) while breathing through a combined inspiratory and expiratory resistance and 4·0 ± 1·3 ml min(-1) 1 min after unloading. Diastolic blood flow was about one-third the systolic blood flow. The changes in blood flows were consistent with those in iEMG. No change in mean blood flow was observed between inspiration and expiration, suggesting a balance in the perfusion of external and internal muscles during breathing. In conclusion, ED is a feasible technique for non-invasive, real-time measurement of intercostal blood flow in humans. In healthy subjects, mean blood flow appeared tightly matched to iEMG activity. This technique may provide a way to assess the vascular adaptations induced by diseases in which respiratory work is increased or cardiac blood flow altered. © 2015 Scandinavian Society of Clinical Physiology and Nuclear Medicine. Published by John Wiley & Sons Ltd.

  16. Time course of metabolic findings in coronary occlusion and reperfusion and their role for assessing myocardial salvage

    Energy Technology Data Exchange (ETDEWEB)

    Schwaiger, M.


    The techniques currently used to assess myocardial infarction are limited in their ability to determine the amount of viable myocardium after a temporary ischemic event. Blood flow and segmental function may not necessarily demonstrate salvage, whereas metabolic parameters will determine cell survival. In a dog open chest model, short occlusion times of 20 min and subsequent reperfusion using C-11 palmitate as an index of fatty acid metabolism showed depresssion of fatty acid oxidation, which recovered after 3 hours of reperfusion, indicating the partial reversibility of the ischemic condition. In more extensive studies, using positron emission tomography (PET) and, as an indicator of glucose metabolism, fluoro-F-18-deoxyglucose (FDG); N-13 ammonia in addition to C-11 palmitate for the determination of blood flow; and ultrasonic crystals to measure shortening in the reperfused and control territories, the duration of occlusion was 3h. Metabolic studies were repeated 24 h, 1 week, and 4 weeks after the ischemic injury. Reperfused viable myocardium exhibited residual glucose metabolism with FDG, whereas fatty acid oxidation remained impaired for a longer period. Gradual metabolic recovery during a 4-week period was associated with the prolonged recovery of regional function, whereas a lack of residual metabolic activity indicated that little change in function was likely to occur. Increased FDG uptake and impaired C-11 palmitate turnover are characteristic of reversibly injured tissue. Therefore, PET studies may offer a unique potential for the evaluation of therapeutic measures such as thrombolysis and early revascularization.

  17. Effect of systemic piracetam treatment on flap survival and vascular endothelial growth factor expression after ischemia-reperfusion injury. (United States)

    Tuncer, Serhan; Ayhan, Suhan; Findikcioglu, Kemal; Ergun, Hakan; Tuncer, Ilhan


    The effects of piracetam on flap survival, ischemia-reperfusion (I/R) injury, and vascular endothelial growth factor (VEGF) expression were evaluated in this study. Unipedicled epigastric flap model was used in 36 rats and was evaluated within 4 groups. The flap was elevated and untreated in Group 1. Postoperative piracetam treatment was given for 7 days in Group 2. In Group 3, 4 hours of ischemia and 2 hours of reperfusion were applied. I/R was applied to Group 4 and piracetam was given 30 minutes before reperfusion and postoperatively for 7 days. Laser Doppler flowmetry was used to measure blood flow changes. VEGF expression was determined using immunohistochemical methods on tissue samples taken after the completion of 2 hours reperfusion in groups 3 and 4. Flap necrosis was measured on the day 7 in all groups. Blood flow rates did not show significant difference between piracetam treated and untreated I/R groups. Piracetam significantly reduced necrosis area both in ischemic and nonischemic flaps ( P piracetam-treated Group 4 compared with Group 3 ( P = 0.005). This experimental study demonstrates that systemic piracetam treatment improves survival of pedicled flaps, reduces necrosis amounts, and increases VEGF expression in I/R induced flaps. © Thieme Medical Publishers.

  18. Face cooling with mist water increases cerebral blood flow during exercise: Effect of changes in facial skin blood flow

    Directory of Open Access Journals (Sweden)

    Taiki eMiyazawa


    Full Text Available Facial cooling (FC increases cerebral blood flow (CBF at rest and during exercise; however, the mechanism of this response remains unclear. The purpose of the present study was to test our hypothesis that FC causes facial vasoconstriction that diverts skin blood flow (SkBFface towards the middle cerebral artery (MCA Vmean at rest and to a greater extent during exercise. Nine healthy young subjects (20 ± 2 yrs. underwent 3 minutes of FC by fanning and spraying the face with a mist of cold water (~4˚C at rest and during steady-state exercise (heart rate of 120 bpm. We focused on the difference between the averaged data acquired from 1 min immediately before FC and last 1 min of FC. SkBFface, MCA Vmean and MAP were higher during exercise than at rest. As hypothesized, FC decreased SkBFface at rest (-32 ± 4 % and to a greater extent during exercise (-64 ± 10%, P=0.012. Although MCA Vmean was increased by FC (Rest, +1.4 ± 0.5 cm/s; Exercise, +1.4 ± 0.6 cm/s, the amount of the FC-evoked changes in MCA Vmean at rest and during exercise differed among subjects. In addition, changes in MCA Vmean with FC did not correlate with concomitant changes in SkBFface (r=0.095, P=0.709. MAP was also increased by FC (Rest, +6.2 ± 1.4 mmHg; Exercise, +4.2 ± 1.2 mmHg. These findings suggest that the FC induced increase in CBF during exercise could not be explained only by change in SkBFface.

  19. Influence of 5-hydroxytryptamine (serotonin) on blood flow in the dog pulp

    Energy Technology Data Exchange (ETDEWEB)

    Kim, S.; Trowbridge, H.O.; Dorscher-Kim, J.E.


    The effect of intra-arterial injection of 5-hydroxytryptamine (5-HT) on pulpal blood flow of the dog was determined using the 15-micron radioisotope-labeled microsphere injection method. Pulpal blood flow was significantly reduced following the 5-HT injection. This decrease in blood flow appeared to be due to vasoconstriction as determined by an increase in pulpal vascular hindrance. However, our findings do not preclude the possibility that blood flow was reduced as a result of passive compression of venules produced by vasodilation in a low-compliance environment.

  20. Modeling cerebral blood flow during posture change from sitting to standing

    DEFF Research Database (Denmark)

    Ottesen, Johnny T.; Olufsen, M.; Tran, H.T.


    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...

  1. Quantitative retinal blood flow mapping from fluorescein videoangiography using tracer kinetic modeling. (United States)

    Tichauer, Kenneth M; Guthrie, Micah; Hones, Logan; Sinha, Lagnojita; St Lawrence, Keith; Kang-Mieler, Jennifer J


    Abnormal retinal blood flow (RBF) has been associated with numerous retinal pathologies, yet existing methods for measuring RBF predominantly provide only relative measures of blood flow and are unable to quantify volumetric blood flow, which could allow direct patient to patient comparison. This work presents a methodology based on linear systems theory and an image-based arterial input function to quantitatively map volumetric blood flow from standard fluorescein videoangiography data, and is therefore directly translatable to the clinic. Application of the approach to fluorescein retinal videoangiography in rats (4 control, 4 diabetic) demonstrated significantly higher RBF in 4-5 week diabetic rats as expected from the literature.

  2. Noninvasive color Doppler sonography of uterine blood flow throughout pregnancy in sheep and goats. (United States)

    Elmetwally, M; Rohn, K; Meinecke-Tillmann, S


    In contrast to cattle or horses, uterine blood flow in small ruminants has been investigated predominantly after surgical intervention and chronic instrumentation. The objective of the present study was to investigate the clinical applicability of noninvasive color Doppler sonography to characterize blood flow in the maternal uterine artery of sheep, n = 11 (18 pregnancies) and goats, n = 11 (20 pregnancies). The following parameters were measured transrectally or transabdominally: blood flow volume, time-averaged maximum velocity (TAMV), resistance index (RI), pulsatility index (PI), Time-averaged mean velocity, impedance of blood flow (AB or systolic/diastolic [S/D] velocity ratio), peak velocity of blood flow and blood flow acceleration. Examinations started 2 weeks after breeding and continued at 2-week intervals until parturition. Outcomes for sheep and goats were similar and will be discussed together. Based on noninvasive color Doppler sonography, blood flow volume increased (approximately 60-fold, P sheep and goats. Furthermore, for uterine artery blood flow, there was an effect of stage of pregnancy on PI and RI (P sheep and goats, respectively, and then decreased until parturition. Similar to PI and RI, vascular impedance of the uterine decreased (P < 0.0001) throughout pregnancy. This is apparently the first study using noninvasive color Doppler sonography of uterine blood flow throughout physiological pregnancy in small ruminants. Clearly, this technology facilitates repeated, noninvasive assessments, with great potential for future studies.

  3. Preserved Collateral Blood Flow in the Endovascular M2CAO Model Allows for Clinically Relevant Profiling of Injury Progression in Acute Ischemic Stroke (United States)

    Little, Philip; Kvist, Ola; Grankvist, Rikard; Jonsson, Stefan; Damberg, Peter; Söderman, Michael; Arnberg, Fabian; Holmin, Staffan


    Interventional treatment regimens have increased the demand for accurate understanding of the progression of injury in acute ischemic stroke. However, conventional animal models severely inhibit collateral blood flow and mimic the malignant infarction profile not suitable for treatment. The aim of this study was to provide a clinically relevant profile of the emergence and course of ischemic injury in cases suitable for acute intervention, and was achieved by employing a M2 occlusion model (M2CAO) that more accurately simulates middle cerebral artery (MCA) occlusion in humans. Twenty-five Sprague-Dawley rats were subjected to Short (90 min), Intermediate (180 min) or Extended (600 min) transient M2CAO and examined longitudinally with interleaved diffusion-, T2- and arterial spin labeling perfusion-weighted magnetic resonance imaging before and after reperfusion. We identified a rapid emergence of cytotoxic edema within tissue regions undergoing infarction, progressing in several distinct phases in the form of subsequent moderation and then reversal at 230 min (p < 0.0001). We identified also the early emergence of vasogenic edema, which increased consistently before and after reperfusion (p < 0.0001). The perfusion of the penumbra correlated more strongly to the perfusion of adjacent tissue regions than did the perfusion of regions undergoing infarction (p = 0.0088). This was interpreted as an effect of preserved collateral blood flow during M2CAO. Accordingly, we observed only limited recruitment of penumbra regions to the infarction core. However, a gradual increase in infarction size was still occurring as late as 10 hours after M2CAO. Our results indicate that patients suffering MCA branch occlusion stand to benefit from interventional therapy for an extended time period after the emergence of ischemic injury. PMID:28068417


    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


    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. Blood flow characteristics in the ascending aorta after TAVI compared to surgical aortic valve replacement. (United States)

    Trauzeddel, Ralf Felix; Löbe, Ulrike; Barker, Alex J; Gelsinger, Carmen; Butter, Christian; Markl, Michael; Schulz-Menger, Jeanette; von Knobelsdorff-Brenkenhoff, Florian


    Ascending aortic blood flow characteristics are altered after aortic valve surgery, but the effect of transcatheter aortic valve implantation (TAVI) is unknown. Abnormal flow may be associated with aortic and cardiac remodeling. We analyzed blood flow characteristics in the ascending aorta after TAVI in comparison to conventional stented aortic bioprostheses (AVR) and healthy subjects using time-resolved three-dimensional flow-sensitive cardiovascular magnetic resonance imaging (4D-flow MRI). Seventeen patients with TAVI (Edwards Sapien XT), 12 with AVR and 9 healthy controls underwent 4D-flow MRI of the ascending aorta. Target parameters were: severity of vortical and helical flow pattern (semiquantitative grading from 0 = none to 3 = severe) and the local distribution of systolic wall shear stress (WSSsystole). AVR revealed significantly more extensive vortical and helical flow pattern than TAVI (p = 0.042 and p = 0.002) and controls (p flow than controls (p blood flow eccentricity (64.7 and 66.7%, respectively), whereas controls showed central blood flow (88.9%). TAVI and AVR exhibited an asymmetric distribution of WSSsystole in the mid-ascending aorta with local maxima at the right anterior aortic wall and local minima at the left posterior wall. In contrast, controls showed a symmetric distribution of WSSsystole along the aortic circumference. Blood flow was significantly altered in the ascending aorta after TAVI and AVR. Changes were similar regarding WSSsystole distribution, while TAVI resulted in less helical and vortical blood flow.

  6. Effects of friction massage of the popliteal fossa on blood flow velocity of the popliteal vein (United States)

    Iwamoto, Koji; Mizukami, Masafumi; Asakawa, Yasutsugu; Endo, Yusuke; Takata, Yuichi; Yoshikawa, Kenichi; Yoshio, Masaharu


    [Purpose] Friction massage (friction) of the popliteal fossa is provided for the purpose of relieving pain related to circulatory disorders by improving venous flow in the lower legs. The purpose of this study is to verify the effects of enhancing the venous flow based on measuring the blood flow velocity of the popliteal vein before and after providing friction to the patients. [Subjects and Methods] Fifteen healthy male university students participated in the study. The Doppler ultrasonography (DU) was used to measure the blood flow velocity of the popliteal vein, in order to verify the effects of enhancing the venous flow by comparing the measured values before and after a friction massage. [Results] The result of comparing the blood flow velocity before and after providing friction showed that there was a significant increase after friction. [Conclusion] This study proved that friction to the popliteal fossa is effectively enhances venous flow by increasing the blood flow velocity in the popliteal vein.

  7. Mathematical analysis of non-Newtonian blood flow in stenosis narrow arteries. (United States)

    Sriyab, Somchai


    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. Dynamic change of collateral flow varying with distribution of regional blood flow in acute ischemic rat cortex (United States)

    Wang, Zhen; Luo, Weihua; Zhou, Fangyuan; Li, Pengcheng; Luo, Qingming


    Cerebral blood flow (CBF) is critical for the maintenance of cerebral function by guaranteed constant oxygen and glucose supply to brain. Collateral channels (CCs) are recruited to provide alternatives to CBF to ischemic regions once the primary vessel is occluded during ischemic stroke. However, the knowledge of the relationship between dynamic evolution of collateral flow and the distribution of regional blood flow remains limited. In this study, laser speckle imaging was used to assess dynamic changes of CCs and regional blood flow in a rat cortex with permanent middle cerebral artery occlusion (MCAo). We found that CCs immediately provided blood flow to ischemic territories after MCAo. More importantly, there were three kinds of dynamic changes of CCs during acute stroke: persistent CC, impermanent CC, and transient CC, respectively, related to different distributions of regional blood flow. Although there was the possible occurrence of peri-infarct depolarization (PID) during ischemia, there was no obvious significance about the onset time and duration of CCs between rats with and without PID. These results suggest that the initial arising of CCs does not ensure their persistence, and that collateral flow could be varied with distribution of regional blood flow in acute ischemic stroke, which may facilitate the understanding of collateral recruitment and promote the development of collateral therapeutics in the future.

  9. Simple Radiowave-Based Method For Measuring Peripheral Blood Flow Project (United States)

    Oliva-Buisson, Yvette J.


    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.

  10. Numerical Modeling of Interstitial Fluid Flow Coupled with Blood Flow through a Remodeled Solid Tumor Microvascular Network.

    Directory of Open Access Journals (Sweden)

    M Soltani

    Full Text Available Modeling of interstitial fluid flow involves processes such as fluid diffusion, convective transport in extracellular matrix, and extravasation from blood vessels. To date, majority of microvascular flow modeling has been done at different levels and scales mostly on simple tumor shapes with their capillaries. However, with our proposed numerical model, more complex and realistic tumor shapes and capillary networks can be studied. Both blood flow through a capillary network, which is induced by a solid tumor, and fluid flow in tumor's surrounding tissue are formulated. First, governing equations of angiogenesis are implemented to specify the different domains for the network and interstitium. Then, governing equations for flow modeling are introduced for different domains. The conservation laws for mass and momentum (including continuity equation, Darcy's law for tissue, and simplified Navier-Stokes equation for blood flow through capillaries are used for simulating interstitial and intravascular flows and Starling's law is used for closing this system of equations and coupling the intravascular and extravascular flows. This is the first study of flow modeling in solid tumors to naturalistically couple intravascular and extravascular flow through a network. This network is generated by sprouting angiogenesis and consisting of one parent vessel connected to the network while taking into account the non-continuous behavior of blood, adaptability of capillary diameter to hemodynamics and metabolic stimuli, non-Newtonian blood flow, and phase separation of blood flow in capillary bifurcation. The incorporation of the outlined components beyond the previous models provides a more realistic prediction of interstitial fluid flow pattern in solid tumors and surrounding tissues. Results predict higher interstitial pressure, almost two times, for realistic model compared to the simplified model.

  11. Cerebral blood flow in Alzheimer’s disease

    Directory of Open Access Journals (Sweden)

    Roher AE


    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


    Institute of Scientific and Technical Information of China (English)

    毛驰; 王翰章


    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.

  13. 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))


    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).

  14. Vascular Function and Regulation of Blood Flow in Resting and Contracting Skeletal Muscle

    DEFF Research Database (Denmark)

    Nyberg, Michael Permin

    in the regulation of exercise hyperemia. Furthermore, blood flow to contracting leg skeletal muscles is reduced both in essential hypertension and with aging. The potential difference in vasoactive system(s) responsible for the reduction in blood flow in the two conditions is in agreement with the suggestion......The precise matching of blood flow, oxygen delivery and metabolism is essential as it ensures that any increase in muscle work is precisely matched by increases in oxygen delivery. Therefore, understanding the control mechanisms of skeletal muscle blood flow regulation is of great biological...... importance. The present work provides new insight in to vasodilator interactions important for exercise hyperemia and sheds light on mechanisms important for vascular function and regulation of skeletal muscle blood flow in essential hypertension (high blood pressure) and aging and identifies mechanisms...

  15. Effect of loading-dose ticagrelor on coronary blood flow, left ventricular remodeling and myocardial enzyme spectrum in patients with acute myocardial infarction after interventional therapy

    Institute of Scientific and Technical Information of China (English)

    Xiao-Rui Xie; Pu Yang


    Objective:To study the effect of loading-dose ticagrelor on coronary blood flow, left ventricular remodeling and myocardial enzyme spectrum in patients with acute myocardial infarction after interventional therapy.Methods: A total of 86 patients with acute myocardial infarction who received emergency PCI in our hospital between May 2013 and May 2016 were selected and randomly divided into two groups, ticagrelor group received perioperative ticagrelor therapy and clopidogrel group received perioperative clopidogrel therapy. After PCI, coronary blood flow reperfusion was evaluated, serum myocardial remodeling indexes and myocardial enzymes were determined, and cardiac color Doppler ultrasonography was conducted to determine the cardiac function indexes.Results:TIMI grading and TMPG grading of ticagrelor group after PCI were significantly higher than those of clopidogrel group; serum MMP9, BNP, CITP, PICP, PIIINP, CK, CK-MB, cTnI and cTnT content of ticagrelor group 24h after operation were significantly lower than those of clopidogrel group; LVEDD, LVSED and LVMI of ticagrelor group 2 weeks after operation were significantly lower than those of clopidogrel group while LVEF was significantly higher than that of clopidogrel group.Conclusion:Peri-PCI loading-dose ticagrelor can improve coronary blood perfusion and reduce ventricular remodeling and myocardial injury in patients with acute myocardial infarction.

  16. Coupling between arterial and venous cerebral blood flow during postural change. (United States)

    Ogoh, Shigehiko; Washio, Takuro; Sasaki, Hiroyuki; Petersen, Lonnie G; Secher, Niels H; Sato, Kohei


    In supine humans the main drainage from the brain is through the internal jugular vein (IJV), but the vertebral veins (VV) become important during orthostatic stress because the IJV is partially collapsed. To identify the effect of this shift in venous drainage from the brain on the cerebral circulation, this study addressed both arterial and venous flow responses in the "anterior" and "posterior" parts of the brain when nine healthy subjects (5 men) were seated and flow was manipulated by hyperventilation and inhalation of 6% carbon dioxide (CO2). From a supine to a seated position, both internal carotid artery (ICA) and IJV blood flow decreased (P = 0.004 and P = 0.002), while vertebral artery (VA) flow did not change (P = 0.348) and VV flow increased (P = 0.024). In both supine and seated positions the ICA response to manipulation of end-tidal CO2 tension was reflected in IJV (r = 0.645 and r = 0.790, P blood flow (r = 0.771 and r = 0.828, P blood flow did not affect venous outflow, but the decrease in IJV blood flow was associated with the increase in VV blood flow (r = 0.479, P = 0.044). In addition, the increase in VV blood flow when seated was reflected in VA blood flow (r = 0.649, P = 0.004), and the two flows were coupled during manipulation of the end-tidal CO2 tension (supine, r = 0.551, P = 0.004; seated, r = 0.612, P blood flow when seated and that VV may influence VA blood flow.

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

    DEFF Research Database (Denmark)

    Simonsen, L; Bülow, J; Astrup, A


    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 fore......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...

  18. Analysis of Systolic Backflow and Secondary Helical Blood Flow in the Ascending Aorta Using Vector Flow Imaging

    DEFF Research Database (Denmark)

    Hansen, Kristoffer Lindskov; Møller-Sørensen, Hasse; Kjaergaard, Jesper


    Secondary rotational flow and systolic backflow are seen in the ascending aorta and, in this study, were analyzed with the vector velocity method transverse oscillation. Twenty-five patients were scanned intra-operatively, and the vector velocities were related to estimates of transesophageal...... that backflow is injurious and that secondary flow is a normal flow phenomenon. The study also shows that transverse oscillation can provide new information on blood flow in the ascending aorta....

  19. Pretreatment with low doses of acenocoumarol inhibits the development of acute ischemia/reperfusion-induced pancreatitis. (United States)

    Warzecha, Z; Sendur, P; Ceranowicz, P; Dembinski, M; Cieszkowski, J; Kusnierz-Cabala, B; Tomaszewska, R; Dembinski, A


    Coagulative disorders are known to occur in acute pancreatitis and are related to the severity of this disease. Various experimental and clinical studies have shown protective and therapeutic effect of heparin in acute pancreatitis. Aim of the present study was to determine the influence of acenocoumarol, a vitamin K antagonist, on the development of acute pancreatitis. Studies were performed on male Wistar rats weighing 250 - 270 g. Acenocoumarol at the dose of 50, 100 or 150 μg/kg/dose or vehicle were administered once a day for 7 days before induction of acute pancreatitis. Acute pancreatitis was induced in rats by pancreatic ischemia followed by reperfusion. The severity of acute pancreatitis was assessed after 5-h reperfusion. Pretreatment with acenocoumarol given at the dose of 50 or 100 μg/kg/dose reduced morphological signs of acute pancreatitis. These effects were accompanied with a decrease in the pancreatitis-evoked increase in serum activity of lipase and serum concentration of pro-inflammatory interleukin-1β. Moreover, the pancreatitis-evoked reductions in pancreatic DNA synthesis and pancreatic blood flow were partially reversed by pretreatment with acenocoumarol given at the dose of 50 and 100 μg/kg/dose. Administration of acenocoumarol at the dose of 150 μg/kg/dose did not exhibit any protective effect against ischemia/reperfusion-induced pancreatitis. We concluded that pretreatment with low doses of acenocoumarol reduces the severity of ischemia/reperfusion-induced acute pancreatitis.

  20. [Effect of electroacupuncture on inflammatory injury induced by intestinal ischemia/reperfusion in rats]. (United States)

    Yao, Jia-Rui; Shi, Xian; Hu, Sen; Zhong, Yu-Xian; Liu, Wei-Wei; Zhao, Ying


    To observe the protective effect of electroacupuncture (EA) at "Zusanli" (ST 36) on inflammatory injury induced by intestinal ischemia/reperfusion (I/R) in rats. Forty-eight Wistar rats were randomly divided into a sham injury group, a model group, an EA group and a sham EA group, 12 rats in each group. Intestinal I/R rat models were established by method of clamping with occlusion of superior mesenteric artery (SMA) for 45 min followed by reperfusion. The EA group was treated with EA (2.5 mA, 2 Hz/100 Hz, 0.5 h) at "Zusanli" (ST 36) 30 min before reperfusion, and at the same time, the sham EA group was treated with fast insertion at two non-meridian acupoints on skin surface (2 cm horizontally away from linea alba abdominis and about 5 cm paralleled to cartilago ensiformis downward). No interventions were added on the sham injury group and the model group. The degree of pathological injury in intestines, water rate of intestines, diamine oxidase (DAO) activity and intestinal mucosal blood flow (IMBF) were examined at 1 h and 3 h after reperfusion. At 1 h and 3 h after reperfusion, the intestinal pathological injury in EA group was significantly attenuated compared with that in model group, and the intestinal water rate of (74.00 +/- 2.11)% and (78.78 +/- 0.80)% in EA group were significantly lower than (80.69 +/- 1.66)% and (83.17 +/- 2.08)% in model group (both P 0.05). Electroacupuncture can not only reduce the inflammatory injury induced by intestinal IR but also increase intestinal blood supply so as to protect the intestine function.

  1. 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)


    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.)

  2. Evaluation of changes of intracranial blood flow after carotid artery stenting using digital subtraction angiography flow assessment

    Institute of Scientific and Technical Information of China (English)

    Hajime; Wada; Masato; Saito; Kyousuke; Kamada


    AIM: To evaluate the changes of intracranial blood flow after carotid artery stenting(CAS), using the flow assessment application "Flow-Insight", which was developed in our department.METHODS: Twenty patients treated by CAS participated in this study. We analyzed the change in concentration of the contrast media at the anterior-posterior and profile view image with the flow assessment application "Flow-Insight". And we compared the results with N-isopropyl-p-[123I] iodoamphetamine-single-photon emission computed tomography(IMP SPECT) performed before and after the treatment. RESULTS: From this study, 200% of the parameter "blood flow" change in the post/pre-treatment is suggested as the critical line of the hyperperfusion syndrome arise. Although the observed blood flow increase in the digital subtraction angiography system did not strongly correlate with the rate of increase of SPECT, the "Flow-Insight" reflected the rate of change of the vessels well. However, for patients with reduced reserve blood flow before CAS, a highly elevated site was in agreement with the site analysis results. CONCLUSION: We concluded that the cerebral angiography flow assessment application was able to more finely reveal hyperperfusion regions in the brain after CAS compared to SPECT.

  3. Autoregulation of cerebral blood flow in experimental focal brain ischemia. (United States)

    Dirnagl, U; Pulsinelli, W


    The relationship between systemic arterial pressure (SAP) and neocortical microcirculatory blood-flow (CBF) in areas of focal cerebral ischemia was studied in 15 spontaneously hypertensive rats (SHRs) anesthetized with halothane (0.5%). Ischemia was induced by ipsilateral middle cerebral artery/common carotid artery occlusion and CBF was monitored continuously in the ischemic territory using laser-Doppler flowmetry during manipulation of SAP with I-norepinephrine (hypertension) or nitroprusside (hypotension). In eight SHRs not subjected to focal ischemia, we demonstrated that 0.5% halothane and the surgical manipulations did not impair autoregulation. Autoregulation was partly preserved in ischemic brain tissue with a CBF of greater than 30% of preocclusion values. In areas where ischemic CBF was less than 30% of preocclusion values, autoregulation was completely lost. Changes in SAP had a greater influence on CBF in tissue areas where CBF ranged from 15 to 30% of baseline (9% change in CBF with each 10% change in SAP) than in areas where CBF was less than 15% of baseline (6% change in CBF with each 10% change in SAP). These findings demonstrate that the relationship between CBF and SAP in areas of focal ischemia is highly dependent on the severity of ischemia. Autoregulation is lost in a gradual manner until CBF falls below 30% of normal. In areas without autoregulation, the slope of the CBF/SAP relationship is inversely related to the degree of ischemia.

  4. Blood flow dynamics, atherosclerosis and bypass graft failure. (United States)

    Langille, B L; Ojha, M


    Atherosclerosis occurs at reproducible sites in the arterial tree and intimal proliferation that leads to bypass graft occlusion also show a well-defined focal distribution. These observations have led to the hypothesis that local blood flow conditions, especially low or fluctuating shear stresses, are important in the development of both disorders. Basic research using both cell culture and animal models has revealed that endothelial cell biology is very sensitive to local shear stresses and rapid progress is being made in characterizing how endothelial cells transduce shear stress. Endothelial sensitivity to shear stress affects control of hemostasis, leukocyte adherence and transmigration, growth factor production, vasomotor responses, endothelial repair and arterial wall remodeling, all of which can be expected to influence development of vascular pathologies. Also, substantial progress has been made in characterizing complex local hemodynamics at relevant arterial sites; however, further progress is needed in this area, as well as in the extrapolation of advances in basic vascular biology to human vascular disease. (Trends Cardiovasc Med 1997;7:111-118). © 1997, Elsevier Science Inc.

  5. Cerebral blood flow in sickle cell cerebrovascular disease

    Energy Technology Data Exchange (ETDEWEB)

    Huttenlocher, P.R.; Moohr, J.W.; Johns, L.; Brown, F.D.


    Cerebral blood flow (CBF) has been studied by the xenon-133 (/sup 133/Xe) inhalation method in 16 children with suspected sickle cell cerebrovascular disease. Abnormalities consisting of decreases in total, hemispheral, or regional CBF were found in 17 of 26 studies. Eleven studies performed immediately after stroke, transient ischemic attack, or depression of state of alertness showed abnormalities. In addition to confirming regional cerebrovascular insufficiency in children with stroke due to major cerebral artery occlusion, the method detected diffuse decrease in CBF in children with stupor, coma, and seizures who had normal angiographic findings. In contrast, six of seven studies obtained after exchange transfusion or during maintenance on hypertransfusion therapy showed normal findings. The difference between results in patients with acute neurologic disturbances and those receiving transfusion therapy was statistically significant (P less than .005). The data indicate that the /sup 133/Xe method reliably demonstrates cerebrovascular impairment in sickle cell disease. They also suggest that CBF changes in patients with sickle cell disease can be reversed by exchange transfusion and by hypertransfusion therapy. The /sup 133/Xe CBF method may be useful for following up children with sickle cell disease who are at high risk for recurrent stroke.

  6. Determining tumor blood flow parameters from dynamic image measurements (United States)

    Libertini, Jessica M.


    Many recent cancer treatments focus on preventing angiogenesis, the process by which a tumor promotes the growth of large and efficient capillary beds for the increased nourishment required to support the tumor's rapid growth[l]. To measure the efficacy of these treatments in a timely fashion, there is an interest in using data from dynamic sequences of contrast-enhanced medical imaging, such as MRI and CT, to measure blood flow parameters such as perfusion, permeability-surface-area product, and the relative volumes of the plasma and extracellular-extravascular space. Starting with a two compartment model presented by the radiology community[2], this work challenges the application of a simplification to this problem, which was originally developed to model capillary reuptake[3]. While the primary result of this work is the demonstration of the inaccuracy of this simplification, the remainder of the paper is dedicated to presenting alternative methods for calculating the perfusion and plasma volume coefficients. These methods are applied to model data sets based on real patient data, and preliminary results are presented.

  7. Determining tumor blood flow parameters from dynamic image measurements

    Energy Technology Data Exchange (ETDEWEB)

    Libertini, Jessica M [Division of Applied Mathematics, Brown University, Providence, Rhode Island 02906 (United States)], E-mail:


    Many recent cancer treatments focus on preventing angiogenesis, the process by which a tumor promotes the growth of large and efficient capillary beds for the increased nourishment required to support the tumor's rapid growth. To measure the efficacy of these treatments in a timely fashion, there is an interest in using data from dynamic sequences of contrast-enhanced medical imaging, such as MRI and CT, to measure blood flow parameters such as perfusion, permeability-surface-area product, and the relative volumes of the plasma and extracellular-extravascular space. Starting with a two compartment model presented by the radiology community, this work challenges the application of a simplification to this problem, which was originally developed to model capillary reuptake. While the primary result of this work is the demonstration of the inaccuracy of this simplification, the remainder of the paper is dedicated to presenting alternative methods for calculating the perfusion and plasma volume coefficients. These methods are applied to model data sets based on real patient data, and preliminary results are presented.

  8. Unveiling astrocytic control of cerebral blood flow with optogenetics. (United States)

    Masamoto, Kazuto; Unekawa, Miyuki; Watanabe, Tatsushi; Toriumi, Haruki; Takuwa, Hiroyuki; Kawaguchi, Hiroshi; Kanno, Iwao; Matsui, Ko; Tanaka, Kenji F; Tomita, Yutaka; Suzuki, Norihiro


    Cortical neural activities lead to changes in the cerebral blood flow (CBF), which involves astrocytic control of cerebrovascular tone. However, the manner in which astrocytic activity specifically leads to vasodilation or vasoconstriction is difficult to determine. Here, cortical astrocytes genetically expressing a light-sensitive cation channel, channelrhodopsin-2 (ChR2), were transcranially activated with a blue laser while the spatiotemporal changes in CBF were noninvasively monitored with laser speckle flowgraphy in the anesthetised mouse cortex. A brief photostimulation induced a fast transient increase in CBF. The average response onset time was 0.7 ± 0.7 sec at the activation foci, and this CBF increase spread widely from the irradiation spot with an apparent propagation speed of 0.8-1.1 mm/sec. The broad increase in the CBF could be due to a propagation of diffusible vasoactive signals derived from the stimulated astrocytes. Pharmacological manipulation showed that topical administration of a K(+) channel inhibitor (BaCl2; 0.1-0.5 mM) significantly reduced the photostimulation-induced CBF responses, which indicates that the ChR2-evoked astrocytic activity involves K(+) signalling to the vascular smooth muscle cells. These findings demonstrate a unique model for exploring the role of the astrocytes in gliovascular coupling using non-invasive, time-controlled, cell-type specific perturbations.

  9. Myocardial contrast echocardiography to assess perfusion in a mouse model of ischemia/reperfusion injury (United States)

    Hossack, John A.; Li, Yinbo; Christensen, Jonathan P.; Yang, Zequan; French, Brent A.


    Noninvasive approaches for measuring anatomical and physiological changes resulting from myocardial ischemia / reperfusion injury in the mouse heart have significant value since the mouse provides a practical, low-cost model for modeling human heart disease. In this work, perfusion was assessed before, during and after an induced closed- chest, coronary ischemic event. Ultrasound contrast agent, similar to MP1950, in a saline suspension, was injected via cannulated carotid artery as a bolus and imaged using a Siemens Sequoia 512 scanner and a 15L8 intraoperative transducer operating in second harmonic imaging mode. Image sequences were transferred from the scanner to a PC for analysis. Regions of interest were defined in septal and anterior segments of the myocardium. During the ischemic event, when perfusion was diminished in the anterior segment, mean video intensity in the affected segment was reduced by one half. Furthermore, following reperfusion, hyperemia (enhanced blood flow) was observed in the anterior segment. Specifically, the mean video intensity in the affected segment was increased by approximately 50% over the original baseline level prior to ischemia. Following the approach of Kaul et al., [1], gamma variate curves were fitted to the time varying level of mean video intensity. This foundation suggests the possibility of quantifying myocardial blood flow in ischemic regions of a mouse heart using automated analysis of contrast image data sets. An improved approach to perfusion assessment using the destruction-reperfusion approach [2] is also presented.

  10. Intensive blood pressure lowering increases cerebral blood flow in older subjects with hypertension. (United States)

    Tryambake, Dinesh; He, Jiabao; Firbank, Michael J; O'Brien, John T; Blamire, Andrew M; Ford, Gary A


    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.

  11. Relationship between blood pressure and cerebral blood flow during supine cycling: influence of aging (United States)

    Hoffman, Keegan; Tzeng, Yu-Chieh; Hansen, Alex; Ainslie, Philip N.


    The cerebral pressure-flow relationship can be quantified as a high-pass filter, where slow oscillations are buffered (exercise, previous studies have reported paradoxical transfer function analysis (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

  12. Comparison of instruments for investigation of microcirculatory blood flow and red blood cell concentration (United States)

    O'Doherty, Jim; McNamara, Paul; Clancy, Neil T.; Enfield, Joey G.; Leahy, Martin J.


    The use of laser Doppler perfusion imaging (LDPI) and laser speckle perfusion imaging (LSPI) is well known in the noninvasive investigation of microcirculatory blood flow. This work compares the two techniques with the recently developed tissue viability (TiVi) imaging system, which is proposed as a useful tool to quantify red blood cell concentration in microcirculation. Three systems are evaluated with common skin tests such as the use of vasodilating and vasoconstricting drugs (methlynicotinate and clobetasol, respectively) and a reactive hyperaemia maneuver (using a sphygmomanometer). The devices investigated are the laser Doppler line scanner (LDLS), the laser speckle perfusion imager (FLPI)-both from Moor Instruments (Axminster, United Kingdom)-and the TiVi imaging system (WheelsBridge AB, Linköping, Sweden). Both imaging and point scanning by the devices are used to quantify the provoked reactions. Perfusion images of vasodilatation and vasoconstriction are acquired with both LDLS and FLPI, while TiVi images are acquired with the TiVi imager. Time acquisitions of an averaged region of interest are acquired for temporal studies such as the reactive hyperaemia. In contrast to the change in perfusion over time with pressure, the TiVi imager shows a different response due its measurement of blood concentration rather than perfusion. The responses can be explained by physiological understanding. Although the three devices sample different compartments of tissue, and output essentially different variables, comparisons can be seen between the three systems. The LDLS system proves to be suited to measurement of perfusion in deeper vessels, while FLPI and TiVi showed sensitivity to more superficial nutritional supply. LDLS and FLPI are insensitive to the action of the vasoconstrictor, while TiVi shows the clear boundaries of the reaction. Assessment of the resolution, penetration depth, and acquisition rate of each instrument show complimentary features that should

  13. Fast Blood Vector Velocity Imaging using ultrasound: In-vivo examples of complex blood flow in the vascular system

    DEFF Research Database (Denmark)

    Hansen, Kristoffer Lindskov; Udesen, Jesper; Gran, Fredrik;


    speckle tracking between segments in consecutive speckle images. The flow patterns of six bifurcations and two veins were investigated in-vivo. It was shown: 1) that a stable vortex in the carotid bulb was present opposed to other examined bifurcations, 2) that retrograde flow was present......Conventional ultrasound methods for acquiring color flow images of the blood motion are restricted by a relatively low frame rate and angle dependent velocity estimates. The Plane Wave Excitation (PWE) method has been proposed to solve these limitations. The frame rate can be increased, and the 2-D...... vector velocity of the blood motion can be estimated. The transmitted pulse is not focused, and a full speckle image of the blood can be acquired for each emission. A 13 bit Barker code is transmitted simultaneously from each transducer element. The 2-D vector velocity of the blood is found using 2-D...

  14. Comparison of the effects of dexmedetomidine administered at two different times on renal ischemia/reperfusion injury in rats

    Directory of Open Access Journals (Sweden)

    Edip Gonullu


    Full Text Available Background and objectives: We investigated the effect of dexmedetomidine on ischemic renal failure in rats. Methods: In the present study, 26 male adult Wistar albino rats weighting 230-300 g were randomly separated into four groups: sham-operated (n = 5, ischemia reperfusion (IR (IR group, n = 7, IR/reperfusion treatment with dexmedetomidine (Dex. R group, n = 7 and IR/pre-ischemic treatment with dexmedetomidine (Dex. I group, n = 7. In the first group, sham operation was achieved and renal clamps were not applied. For the IR group, renal ischemia was induced by occlusion of the bilateral renal arteries and veins for 60 min followed by reperfusion for 24 h. For the Dex. R and Dex. I groups, the same surgical procedure as in the IR group was performed, and dexmedetomidine (100 mcg/kg intraperitoneal was administrated at the 5th min after reperfusion and before ischemia. At the end of reperfusion, blood samples were drawn, the rats were sacrificed, and the left kidney was processed for histopathology. Results: The blood urea nitrogen (BUN levels in groups Dex. R and Dex. I were significantly lower than in the IR group (p = 0.015, p = 0.043, although urine flow was significantly higher in group Dex. R (p = 0.003. The renal histopathological score in the IR group was significantly higher than in the other groups. There was no significant difference between the Dex. R and Dex. I groups. Conclusions: The results were shown that administration of dexmedetomidine reduced the renal IR injury histomorphologically. Administration of dexmedetomidine in the reperfusion period was considered as more effective due to increase in urinary output and decrease in BUN levels.

  15. Measurement of temperature decrease caused by blood flow in focused ultrasound irradiation by thermal imaging method (United States)

    Tsuchiya, Takenobu; Hatano, Yuichi; Mori, Yashunori; Shen, Rakushin; Endoh, Nobuyuki


    In this study, to estimate the local temperature changes caused by a thick blood vessel, the temperature distribution in a tissue phantom with a thick blood vessel during focused ultrasound irradiation was measured by a thermal imaging method. The blood flow rate in the simulated blood vessel was varied and the relationship between flow rate and temperature decrease was examined. The phantom using the thermal imaging method is divided into two parts, and the increases in temperature distribution as a function of blood flow rate are measured using a thermocamera under constant ultrasound irradiation. The irradiation conditions of ultrasound waves were a central frequency of 1 MHz, a wave number length of 200 cycles, and a duty ratio of 0.2. The irradiation duration was 5 min, and the ultrasound intensity I SPTA was 36 W/cm2. The amount of temperature decrease caused by the cooling effect of blood flow increased with the blood flow rate and it became constant at a certain threshold of blood flow rate. The threshold of blood flow rate is about 250 ml/min.

  16. 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


    The effect of head-up tilt upon subcutaneous and skeletal muscle blood flow in the crus was studied before and during epidural blockade in 10 subjects. Relative changes in blood flow were estimated by the local 133Xe washout technique. In subcutaneous tissue head-up tilt induced a decrease in blo...

  17. Adrenergically stimulated blood flow in brown adipose tissue is not dependent on thermogenesis. (United States)

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


    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.

  18. Contrast sensitivity, ocular blood flow and their potential role in assessing ischaemic retinal disease. (United States)

    Shoshani, Yochai Z; Harris, Alon; Rusia, Deepam; Spaeth, George L; Siesky, Brent; Pollack, Ayala; Wirostko, Barbara


    To examine the definition, evaluation methodology, association to ocular blood flow and potential clinical value of contrast sensitivity (CS) testing in clinical and research settings, focusing in patients with ischemic retinal disease. A review of the medical literature focusing on CS and ocular blood flow in ischemic retinal disease. CS may be more sensitive than other methods at detecting subtle defects or improvements in primarily central retinal ganglion cell function early on in a disease process. CS testing attempts to provide spatial detection differences which are not directly assessed with standard visual acuity chart testing. Analyzing all studies that have assessed both CS change and ocular blood flow, it is apparent that both choroidal circulation and retinal circulation may have an important role in influencing CS. The concept that CS is directly influenced by ocular blood flow is supported by reviewing the studies involving both. Although the studies in the literature have not established a direct cause and effect relationship per se, the literature review makes it logical to assume that changes in retinal and choroidal blood flow influence CS. This raises the possibility that a subjective visual characteristic, specifically CS, may be able to be evaluated more objectively by studying blood flow. It appears appropriate to study the relationship between blood flow and CS more extensively to develop improved ways of measuring various aspects of blood flow to the eye and to best quantify early changes in visual function. © 2011 The Authors. Acta Ophthalmologica © 2011 Acta Ophthalmologica Scandinavica Foundation.

  19. Changes in subcutaneous blood flow during locally applied negative pressure to the skin

    DEFF Research Database (Denmark)

    Skagen, K; Henriksen, O


    The effect of locally applied subatmospheric pressure on subcutaneous blood flow was studied in 12 healthy subjects. Blood flow was measured on the forearm by the local 133Xe wash-out technique. Air suction between 10 mmHg and 250 mmHg was applied to the skin. Subatmospheric pressure of 20 mmHg c...

  20. Should blood flow during cardiopulmonary bypass be individualized more than to body surface area?

    DEFF Research Database (Denmark)

    Thomassen, Sisse Anette; Larsson, A; Andreasen, Jan Jesper;

    Blood flow during cardiopulmonary bypass (CPB) is calculated on body surface area (BSA). Increasing comorbidity, age and weight of today's cardiac patients question this calculation as it may not reflect individual metabolic requirement. The hypothesis was that a measured cardiac index (CI) prior...... not improve cerebral and systemic oxygenation compared to a blood flow based on BSA....

  1. 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;


    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 im...

  2. Leg blood flow measurements using venous occlusion plethysmography during head-up tilt.

    NARCIS (Netherlands)

    Kooijman, M.; Poelkens, F.; Rongen, G.A.; Smits, P.; Hopman, M.T.E.


    We tested whether venous occlusion plethysmography (VOP) is an appropriate method to measure calf blood flow (CBF) during head-up tilt (HUT). CBF measured with VOP was compared with superficial femoral artery blood flow as measured by Doppler ultrasound during incremental tilt angles. Measurements o

  3. Dynamic noise correction for IVUS quantitative volume blood flow: methods and numerical validation.

    NARCIS (Netherlands)

    Lupotti, F.A.; Korte, C.L. de; Mastik, F.; Steen, A.F.W. van der


    In recent years, a new method to measure transverse blood flow based on the decorrelation of the radio-frequency (RF) signals, has been developed. Transverse blood flow estimation may be influenced by noise. In this paper, we investigated a new correlation-based method for noise correction. The deco

  4. On the pathogenesis of bedsores. Skin blood flow cessation by external pressure on the back

    DEFF Research Database (Denmark)

    Larsen, B; Holstein, P; Lassen, N A


    This paper is devoted to elucidation of the question: Which external pressure is required to stop skin blood flow at the skin - support interface in humans lying on the back in the supine position? Cessation of blood flow was recorded as cessation of washout of an intracutaneous depot of 131I-ant...

  5. Blood flow response to electrically induced twitch and tetanic lower-limb muscle contractions.

    NARCIS (Netherlands)

    Janssen, T.W.; Hopman, M.T.E.


    OBJECTIVES: To compare the effect of electric stimulation (ES)-induced twitch with tetanic leg muscle contractions on blood flow responses and to assess blood flow responses in the contralateral inactive leg. DESIGN: Intervention with within-subject comparisons. SETTING: University research laborato

  6. Effect of intracapsular hyperpressure on femoral head blood flow. Laser Doppler flowmetry in dogs. (United States)

    Vegter, J; Klopper, P J


    Intracapsular hyperpressure in the hip joint of dogs affected femoral head blood flow, especially in the juvenile animals. Graphic recording of the laser Doppler signal curve using rapid sampling time demonstrated venous hip joint tamponade in both juvenile and adult dogs. Laser Doppler flowmetry seems to be a sensitive and reproducible method to demonstrate femoral-head blood-flow changes.

  7. 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))


    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).

  8. Cerebral oxygen extraction, oxygen consumption, and regional cerebral blood flow during the aura phase of migraine

    DEFF Research Database (Denmark)

    Friberg, L; Olesen, Jes; Lassen, N A


    The aura phase of migraine is associated with focal blood flow changes, but it has been largely unknown whether these changes are correlated to changes in the cerebral metabolism.......The aura phase of migraine is associated with focal blood flow changes, but it has been largely unknown whether these changes are correlated to changes in the cerebral metabolism....

  9. Insulin partially reverses deficits in peripheral nerve blood flow and conduction in experimental diabetes

    NARCIS (Netherlands)

    Gispen, W.H.; Biessels, G.J.; Stevens, E.J.; Mahmood, S.J.; Tomlinson, D.R.


    Decreased nerve blood flow may be a pathogenetic factor in diabetic neuropathy. Previously it was shown that insulin treatment, commenced at the onset of streptozotocin-diabetes, prevents the development of a nerve blood flow deficit in the diabetic rat. The present study sought to determine the eff

  10. Phase-Contrast Magnetic Resonance Angiography Measurements of Global Cerebral Blood Flow in the Neonate

    NARCIS (Netherlands)

    Benders, Manon J. N. L.; Hendrikse, Jeroen; de Vries, Linda S.; van Bel, Frank; Groenendaal, Floris


    Cerebral blood flow (CBF) alterations are important in pathogenesis of neonatal ischemic/hemorrhagic brain damage. In clinical practice, estimation of neonatal CBF is mostly based on Doppler-measured blood flow velocities in major intracranial arteries. Using phase-contrast magnetic resonance angiog

  11. Quantitative evaluation of myocardial function by a volume-normalized map generated from relative blood flow

    Energy Technology Data Exchange (ETDEWEB)

    Fukami, Tadanori [Department of Bio-system Engineering, Faculty of Engineering, Yamagata University, Yonezawa, Yamagata 992-8510 (Japan); Sato, Hidenori [Department of Bio-system Engineering, Faculty of Engineering, Yamagata University, Yonezawa, Yamagata 992-8510 (Japan); Wu, Jin [Graduate School of Comprehensive Human Sciences, University of Tsukuba, Ibaraki 305-8575 (Japan); Lwin, Thet-Thet- [Graduate School of Comprehensive Human Sciences, University of Tsukuba, Ibaraki 305-8575 (Japan); Yuasa, Tetsuya [Department of Bio-system Engineering, Faculty of Engineering, Yamagata University, Yonezawa, Yamagata 992-8510 (Japan); Kawano, Satoru [Graduate School of Comprehensive Human Sciences, University of Tsukuba, Ibaraki 305-8575 (Japan); Iida, Keiji [Graduate School of Comprehensive Human Sciences, University of Tsukuba, Ibaraki 305-8575 (Japan); Akatsuka, Takao [Department of Bio-system Engineering, Faculty of Engineering, Yamagata University, Yonezawa, Yamagata 992-8510 (Japan); Hontani, Hidekata [Department of Computer Science and Engineering, Nagoya Institute of Technology, Aichi 466-8555 (Japan); Takeda, Tohoru [Graduate School of Comprehensive Human Sciences, University of Tsukuba, Ibaraki 305-8575 (Japan); Tamura, Masao [Graduate School of Comprehensive Human Sciences, University of Tsukuba, Ibaraki 305-8575 (Japan); Yokota, Hiroshi [Graduate School of Comprehensive Human Sciences, University of Tsukuba, Ibaraki 305-8575 (Japan)


    Our study aimed to quantitatively evaluate blood flow in the left ventricle (LV) of apical hypertrophic cardiomyopathy (APH) by combining wall thickness obtained from cardiac magnetic resonance imaging (MRI) and myocardial perfusion from single-photon emission computed tomography (SPECT). In this study, we considered paired MRI and myocardial perfusion SPECT from ten patients with APH and ten normals. Myocardial walls were detected using a level set method, and blood flow per unit myocardial volume was calculated using 3D surface-based registration between the MRI and SPECT images. We defined relative blood flow based on the maximum in the whole myocardial region. Accuracies of wall detection and registration were around 2.50 mm and 2.95 mm, respectively. We finally created a bull's-eye map to evaluate wall thickness, blood flow (cardiac perfusion) and blood flow per unit myocardial volume. In patients with APH, their wall thicknesses were over 10 mm. Decreased blood flow per unit myocardial volume was detected in the cardiac apex by calculation using wall thickness from MRI and blood flow from SPECT. The relative unit blood flow of the APH group was 1/7 times that of the normals in the apex. This normalization by myocardial volume distinguishes cases of APH whose SPECT images resemble the distributions of normal cases.

  12. 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

    ].The purpose of this animal study is to investigate the organ hierarchy of brain, liver, kidney and muscle at normal and low blood flows by using dynamic positron tomography (PET-CT) during CPB. Methods CPB at different blood flows will be investigated in an experimental model of six 70 kg pigs...

  13. A disturbed macrocirculatory supply as a determinant for a reduced sciatic nerve blood flow in diabetic rats

    NARCIS (Netherlands)

    Gispen, W.H.; Buren, Th. van; Kappelle, A.C.; Kasbergen, C.M.; Wildt, D.J. de


    The aim of this study was to evaluate macrocirculatory disturbances in relation to the reduced sciatic nerve blood flow seen in diabetic rats. Therefore, both femoral blood flow, the macrocirculatory arterial blood supply to the sciatic nerve, and the microcirculatory neuronal blood flow were measur

  14. Changes in interstitial K+ and pH during exercise: implications for blood flow regulation

    DEFF Research Database (Denmark)

    Juel, Carsten


    of fatigue. It has also been demonstrated with microdialysis that the interstitial decrease in pH during muscle activity is larger than the reduction in blood pH. Ion changes in the interstitium may affect blood flow directly or indirectly. Infusion of K+ into the femoral artery in humans has demonstrated...... that blood flow is affected by changes in K+ as low as 0.1 mmol/L. The vasodilatory effect of K+ can be inhibited with simultaneous barium infusion, indicating that inward rectifier potassium (Kir)channels are involved. Acidosis has a direct effect on blood flow and an indirect effect, mediated by changes...

  15. Magnetic field effect on blood flow of Casson fluid in axisymmetric cylindrical tube: A fractional model (United States)

    Ali, Farhad; Sheikh, Nadeem Ahmad; Khan, Ilyas; Saqib, Muhammad


    The effects of magnetohydrodynamics on the blood flow when blood is represented as a Casson fluid, along with magnetic particles in a horizontal cylinder is studied. The flow is due to an oscillating pressure gradient. The Laplace and finite Hankel transforms are used to obtain the closed form solutions of the fractional partial differential equations. Effects of various parameters on the flow of both blood and magnetic particles are shown graphically. The analysis shows that, the model with fractional order derivatives bring a remarkable changes as compared to the ordinary model. The study highlights that applied magnetic field reduces the velocities of both the blood and magnetic particles.

  16. Gadolinium decreases inflammation related to myocardial ischemia and reperfusion injury

    Directory of Open Access Journals (Sweden)

    Nicolosi Alfred C


    Full Text Available Abstract Background The lanthanide cation, gadolinium (GdCl3 protects the myocardium against infarction following ischemia and reperfusion. Neutrophils and macrophages are the main leukocytes responsible for infarct expansion after reperfusion. GdCl3 interferes with macrophage and neutrophil function in the liver by decreasing macrophage secretion of inflammatory cytokines and neutrophil infiltration. We hypothesized that GdCl3 protects against ischemia and reperfusion injury by decreasing inflammation. We determined the impact of GdCl3 treatment for reperfusion injury on 1 circulating monoctye and neutrophil counts, 2 secretion of inflammatory cytokines, and 3 influx of monocytes and neutrophils into the myocardium. Methods Rats (n = 3-6/gp were treated with saline or GdCl3 (20 μmol/kg 15 min prior to a 30 min period of regional ischemia and 120 min reperfusion. Sham rats were not subject to ischemia. Blood was collected either after 30 min ischemia or 120 min reperfusion and hearts were harvested at 120 min reperfusion for tissue analysis. Blood was analyzed for leukocytes counts and cytokines. Tissue was analyzed for cytokines and markers of neutrophil and monocyte infiltration by measuring myeloperoxidase (MPO and α-naphthyl acetate esterase (ANAE. Results GdCl3 did not affect the number of circulating neutrophils prior to ischemia. Two hours reperfusion resulted in a 2- and 3- fold increase in circulating monocytes and neutrophils, respectively. GdCl3 decreased the number of circulating monocytes and neutrophils during reperfusion to levels below those present prior to ischemia. Furthermore, after 120 min of reperfusion, GdCl3 decreased ANAE and MPO activity in the myocardium by 1.9-fold and 6.5-fold respectively. GdCl3 decreased MPO activity to levels below those measured in the Sham group. Serum levels of the major neutrophil chemoattractant cytokine, IL-8 were increased from pre-ischemic levels during ischemia and reperfusion in both

  17. Numerical simulation of the non-Newtonian blood flow through a mechanical aortic valve. Non-Newtonian blood flow in the aortic root (United States)

    De Vita, F.; de Tullio, M. D.; Verzicco, R.


    This work focuses on the comparison between Newtonian and non-Newtonian blood flows through a bileaflet mechanical heart valve in the aortic root. The blood, in fact, is a concentrated suspension of cells, mainly red blood cells, in a Newtonian matrix, the plasma, and consequently its overall behavior is that of a non-Newtonian fluid owing to the action of the cells' membrane on the fluid part. The common practice, however, assumes the blood in large vessels as a Newtonian fluid since the shear rate is generally high and the effective viscosity becomes independent of the former. In this paper, we show that this is not always the case even in the aorta, the largest artery of the systemic circulation, owing to the pulsatile and transitional nature of the flow. Unexpectedly, for most of the pulsating cycle and in a large part of the fluid volume, the shear rate is smaller than the threshold level for the blood to display a constant effective viscosity and its shear thinning character might affect the system dynamics. A direct inspection of the various flow features has shown that the valve dynamics, the transvalvular pressure drop and the large-scale features of the flow are very similar for the Newtonian and non-Newtonian fluid models. On the other hand, the mechanical damage of the red blood cells (hemolysis), induced by the altered stress values in the flow, is larger for the non-Newtonian fluid model than for the Newtonian one.

  18. Influence of cold-water immersion on limb blood flow after resistance exercise. (United States)

    Mawhinney, Chris; Jones, Helen; Low, David A; Green, Daniel J; Howatson, Glyn; Gregson, Warren


    This study determined the influence of cold (8°C) and cool (22°C) water immersion on lower limb and cutaneous blood flow following resistance exercise. Twelve males completed 4 sets of 10-repetition maximum squat exercise and were then immersed, semi-reclined, into 8°C or 22°C water for 10-min, or rested in a seated position (control) in a randomized order on different days. Rectal and thigh skin temperature, muscle temperature, thigh and calf skin blood flow and superficial femoral artery blood flow were measured before and after immersion. Indices of vascular conductance were calculated (flux and blood flow/mean arterial pressure). The colder water reduced thigh skin temperature and deep muscle temperature to the greatest extent (P cold and cool water similarly reduce femoral artery and cutaneous blood flow responses but not muscle temperature following resistance exercise.

  19. [Changes in palmar skin blood flow, perfusion index and temperature during endoscopic thoracic sympathectomy]. (United States)

    Asano, Maiko; Tanaka, Motoshige; Kusaka, Hitomi; Sakai, Masato; Minami, Toshiaki


    In endoscopic thoracic sympathectomy (ETS), it is required to perform accurate cautery of the sympathetic trunk. Monitoring of palmar skin blood flow and temperature has been used to assess the efficacy of ETS. This study investigated whether Perfusion Index (PI) is useful in assessing palmar skin blood flow and temperature in ETS. We studied 5 patients (1 man, 4 women) with palmar hyperhidrosis who had undergone a total of 10 ETS procedures. We measured skin blood flow, temperature and PI during ETS and evaluated the results. Significant correlations were found between increases in skin blood flow and PI after ETS in cases with the palmar skin temperature just before ETS of below 35 degrees C. In these cases, we can substitute increases in PI with increases in skin blood flow during ETS.

  20. Peculiarities of Blood Flow Changes in Venae Cavae during Experimental Pulmonary Embolism. (United States)

    Evlakhov, V I; Poyassov, I Z; Shaidakov, E V


    The model of acute pulmonary embolism in rabbits demonstrated reduced pulmonary blood flow, cardiac output, left atrial pressure, and blood flow in venae cavae against the background of elevated left pulmonary artery pressure and increased pulmonary vascular resistance. Simultaneously, the blood flow in the superior vena cava decreased to a lesser extent than that in the inferior vena cava, which was a characteristic feature of the model of pulmonary pathology. In contrast, when histamine was infused into the left jugular vein to equally elevate pressure in pulmonary artery as in the above model, the blood flow in the superior vena cava decreased to a greater extent than that in inferior vena cava. During stenosis of inferior vena cava that decreased the cardiac output to the level observed during modeled pulmonary embolism, the blood flows in both venae cavae dropped equally.