A study of the cerebral blood flow pattern and cognitive deficit in Parkinson's disease

International Nuclear Information System (INIS)

Tamaru, Fuyuhiko

1997-01-01

Cerebral blood flow pattern in Parkinson's disease was examined by 123 I-IMP SPECT to determine whether the deficit in cognitive function is reflected in it. The patient group with Parkinson's disease showed deterioration in intelligence (Minimental state examination, Raven's Colored Progressive Matrices) and frontal lobe test (the Wisconsin Card Sorting Test). Though the uptake ratio of prefrontal area/occipital area in 123 I-IMP SPECT study varied widely in the Parkinson's disease group compared to the normal control group, there was no significant difference in the mean. Selective depletion of frontal lobe blood flow was not confirmed in this study. There was no correlation between cerebral blood flow pattern and cognitive functions including frontal lobe function and intelligence. We concluded that the deficit in cognitive function was not reflected in the cerebral blood flow pattern in Parkinson's disease. (author)

Autoradiographic study of the regional distribution of gastric blood flow in portal hypertensive rats

International Nuclear Information System (INIS)

Geraghty, J.G.; Angerson, W.J.; Carter, D.C.

1989-01-01

This study measures regional gastric blood flow in portal hypertensive rats at three separate periods after portal vein ligation using quantitative autoradiography with 14C-labeled iodoantipyrine. The level of corpus mucosal blood flow was significantly reduced in 3-day portal vein-ligated animals compared with sham-operated control animals (30.4 +/- 2.3 vs. 47.1 +/- 5.6 ml/100 g.min). There was no significant difference in corpus mucosal blood flow between portal vein-ligated and sham-operated animals at 7- and 28-day periods, although the level of perfusion was higher in the 28-day portal vein-ligated group. There was no significant difference in antral mucosal or muscle blood flow between portal hypertensive and control animals at any of the study periods. We conclude that the acute period after portal vein ligation is associated with a reduced corpus mucosal microcirculation but that this effect is not sustained in portal hypertensive animals studied at later intervals after portal vein ligation

Microsphere estimates of blood flow: Methodological considerations

International Nuclear Information System (INIS)

von Ritter, C.; Hinder, R.A.; Womack, W.; Bauerfeind, P.; Fimmel, C.J.; Kvietys, P.R.; Granger, D.N.; Blum, A.L.

1988-01-01

The microsphere technique is a standard method for measuring blood flow in experimental animals. Sporadic reports have appeared outlining the limitations of this method. In this study the authors have systematically assessed the effect of blood withdrawals for reference sampling, microsphere numbers, and anesthesia on blood flow estimates using radioactive microspheres in dogs. Experiments were performed on 18 conscious and 12 anesthetized dogs. Four blood flow estimates were performed over 120 min using 1 x 10 6 microspheres each time. The effects of excessive numbers of microspheres pentobarbital sodium anesthesia, and replacement of volume loss for reference samples with dextran 70 were assessed. In both conscious and anesthetized dogs a progressive decrease in gastric mucosal blood flow and cardiac output was observed over 120 min. This was also observed in the pancreas in conscious dogs. The major factor responsible for these changes was the volume loss due to the reference sample withdrawals. Replacement of the withdrawn blood with dextran 70 led to stable blood flows to all organs. The injection of excessive numbers of microspheres did not modify hemodynamics to a greater extent than did the injection of 4 million microspheres. Anesthesia exerted no influence on blood flow other than raising coronary flow. The authors conclude that although blood flow to the gastric mucosa and the pancreas is sensitive to the minor hemodynamic changes associated with the microsphere technique, replacement of volume loss for reference samples ensures stable blood flow to all organs over a 120-min period

Mammary blood flow regulation in the nursing rabbit

International Nuclear Information System (INIS)

Katz, M.; Creasy, R.K.

1984-01-01

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

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

DEFF Research Database (Denmark)

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

2002-01-01

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

The Physics of Coronary Blood Flow

CERN Document Server

Zamir, M

2005-01-01

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

Bone blood flow after spinal paralysis in the rat

International Nuclear Information System (INIS)

Takahashi, H.; Yamamuro, T.; Okumura, H.; Kasai, R.; Tada, K.

1990-01-01

The goal of this study was to investigate the acute and chronic effects of paralysis induced by spinal cord section or sciatic neurotomy on bone blood flow in the rat. Regional bone blood flow was measured in the early stage with the hydrogen washout technique and the change of whole bone blood flow was measured in the early and the late stages with the radioactive microsphere technique. Four to 6 h after cordotomy at the level of the 13th thoracic vertebra, the regional bone blood flow in the denervated tibia increased significantly (p less than 0.01). After hemicordotomy with rhizotomy at the same level, the regional bone blood flow in the denervated tibia increased significantly (p less than 0.05) 6 h postoperatively. The whole bone blood flow in the denervated tibia had also increased significantly (p less than 0.05) at 6 h and at 4 and 12 weeks postoperatively. After sciatic neurotomy, the regional and the whole bone blood flow in the paralytic tibia did not change significantly. The present study demonstrated that monoplegic paralysis caused an increase in bone blood flow in the denervated hind limb from a very early stage. It was suggested that the spinal nervous system contributed to the control of bone blood flow

Self-separation of blood plasma from whole blood during the capillary flow in microchannel

Science.gov (United States)

Nunna, Bharath Babu; Zhuang, Shiqiang; Lee, Eon Soo

2017-11-01

Self-separation of blood plasma from whole blood in microchannels is of great importance due to the enormous range of applications in healthcare and diagnostics. Blood is a multiphase complex fluid, composed of cells suspended in blood plasma. RBCs are the suspended particles whose shape changes during the flow of blood. The primary constituents of blood are erythrocytes or red blood cells (RBCs), leukocytes or white blood cells (WBCs), thrombocytes or platelets and blood plasma. The existence of RBCs in blood makes the blood a non-Newtonian fluid. The current study of separation of blood plasma from whole blood during self-driven flows in a single microchannel without bifurcation, by enhancing the capillary effects. The change in the capillary effect results in a change in contact angle which directly influences the capillary flow. The flow velocity directly influences the net force acting on the RBCs and influence the separation process. The experiments are performed on the PDMS microchannels with different contact angles by altering the surface characteristics using plasma treatment. The change in the separation length is studied during the capillary flow of blood in microchannel. Bharath Babu Nunna is a researcher in mechanical engineering and implementing the novel and innovative technologies in the biomedical devices to enhance the sensitivity of the disease diagnosis.

Quantitative measurement of portal blood flow by magnetic resonance phase contrast. Comparative study of flow phantom and Doppler ultrasound in vivo

International Nuclear Information System (INIS)

Tsunoda, Masatoshi; Kimoto, Shin; Hamazaki, Keisuke; Takeda, Yoshihiro; Hiraki, Yoshio.

1994-01-01

A non-invasive method for measuring portal blood flow by magnetic resonance (MR) phase contrast was evaluated in a flow phantom and 20 healthy volunteers. In a flow phantom study, the flow volumes and mean flow velocities measured by MR phase contrast showed close correlations with those measured by electromagnetic flow-metry. In 20 healthy volunteers, the cross-sectional areas, flow volumes and mean flow velocities measured by MR phase contrast correlated well with those measured by the Doppler ultrasound method. Portal blood flow averaged during the imaging time could be measured under natural breathing conditions by using a large number of acquisitions without the limitations imposed on the Doppler ultrasound method. MR phase contrast is considered to be useful for the non-invasive measurement of portal blood flow. (author)

Radionuclide scanning in a study of the pulmonary blood flow with the open arterial canal

International Nuclear Information System (INIS)

Rizaev, M.N.; Gulyamov, D.S.; Khodzhibekov, M.Kh.; Anvarov, M.A.

1980-01-01

Characteristic features of the distribution of the arterial pulmonary blood flow have been studied in 32 patients with the open arterial flow by lung scanning with albumin macroaggregate and 131 I. Research was conducted using the gamma-Ochamber ''Fo Gamma LFV'' and the scanner ''Magnaskaner 500I''. Disordered distribution of the pulmonary blood flow expressed in its unilateral decrease was detected in 17 patients (52.9%). A higher frequency of pulmonary hypertension was noted in these patients versus those with a relatively normal distribution of the pulmonary blood flow. A severe course of the disease was observed in high pulmonary hypertension combined with sharp suppression of the blood flow in one of the lungs or with signs of the shift from the right to the left side

Assessment of hand blood flow: a modified technique

International Nuclear Information System (INIS)

Kirsh, J.C.; Tepperman, P.S.

1985-01-01

A blood flow artifact has been identified with the conventional bolus-injection technique in radionuclide studies of hand disorders. The artifact, consisting of increased blood flow on the injected side, was demonstrated in 22 of 25 subjects. Using a modified injection technique to allow time for local blood flow to return to the basal state, the artifact could be eliminated in 19 of 23 additional subjects. Use of this simple protocol should help avoid misinterpretation of blood flow asymmetry in the assessment of hand disorders

Bone blood flow and metabolism in humans

DEFF Research Database (Denmark)

Heinonen, Ilkka; Kemppainen, Jukka; Kaskinoro, Kimmo

2012-01-01

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

Quantitative assessment of limb blood flow using Tc-99m labeled red blood cells

International Nuclear Information System (INIS)

Itoh, Kazuo; Shougase, Takashi; Kawamura, Naoyuki; Tsukamoto, Eriko; Nakada, Kunihiro; Sakuma, Makoto; Furudate, Masayori

1987-01-01

A quantitative assessment of limb blood flow using a non-diffusible radioindicator, Tc-99m labeled red blood cells, was reported. This was an application of venous occlusion plethysmography using radionuclide which was originally proposed by M. Fukuoka et al. The peripheral blood flow (mean ± s.e.) of 30 legs in a normal control group was 1.87 ± 0.08 ml/100 ml/min. In heart diseases (46 legs), it was 1.49 ± 0.13 ml/100 ml/min. The limb blood flow between a control group and heart diseases was statistically significant (p < 0.01) in the t-test. The peripheral blood flow at rest between diseased legs and normal legs in occlusive arterial disorders was also statistically significant (p < 0.01) in a paired t-test. RAVOP was done after the completion of objective studies such as radionuclide angiography or ventriculography. Technique and calculation of a blood flow were very easy and simple. RAVOP study which was originally proposed by Fukuoka et al. was reappraised to be hopeful for quantitative measurement of limb blood flow as a non-invasive technique using Tc-99m labeled red blood cells. (author)

Nasal mucosal blood flow after intranasal allergen challenge

International Nuclear Information System (INIS)

Holmberg, K.; Bake, B.; Pipkorn, U.

1988-01-01

The nasal mucosal blood flow in patients with allergic rhinitis was determined at nasal allergen challenges with the 133 Xenon washout method. Determinations were made in 12 subjects before and 15 minutes after challenge with diluent and increasing doses of allergen. The time course was followed in eight subjects by means of repeated measurements during 1 hour after a single allergen dose. Finally, the blood flow was measured after unilateral allergen challenge in the contralateral nasal cavity. A dose-dependent decrease in blood flow was found after nasal challenge with increasing doses of allergens, whereas challenge with diluent alone did not induce any changes. The highest allergen dose, which also induced pronounced nasal symptoms, resulted in a decrease in blood flow of 25% (p less than 0.001). The time-course study demonstrated a maximum decrease in blood flow 10 to 20 minutes after challenge and then a gradual return to baseline. Unilateral allergen challenge resulted in a decrease in blood flow in the contralateral, unchallenged nasal cavity, suggesting that part of the allergen-induced changes in blood flow were reflex mediated

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

will be measured with dynamic PET-CT before CPB and during the different blood flows. Systemic oxygen consumption will be estimated by measurement of mixed venous saturation and lactate, and regional muscle oxygen saturation (tSO2) with near infrared spectroscopy at the lower limb. Result: Preliminary data......].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...... knowledge this is the first study investigating organ hierarchy with dynamic PET-CT during profound systemic ischemia due to suboptimal blood flows during normothermic CPB. References 1. Murphy JM, Hessel II EA, Groom RC. Optimal perfusion during cardiopulmonary bypass: an Evidence-based approach. Anesth...

Regional cerebral blood flow in schizophrenic patients

International Nuclear Information System (INIS)

Sagawa, Katsuo; Sibuya, Isoo; Oiji, Arata; Kawakatsu, Sinobu; Morinobu, Shigeru; Totsuka, Shiro; Kinoshita, Osami; Yazaki, Mitsuyasu.

1990-01-01

Seventy-six schizophrenic patients were examined by a Xe-133 inhalation method to determine regional cerebral blood flow. A decreased blood flow was observed in the frontal lobe, especially in the right inferior part. In a study on the relationship between disease subtypes and regional cerebral blood flow, negative symptoms were found more predominantly associated with dissolution type than delusion type. In the group of dissolution type, a decreased blood flow was observed in both the right inferior frontal lobe and the right upper hemisphere, in comparison to the group of delution type. Patients presenting with auditory hallucination had a significantly higher incidence of both negative and positive symptoms, as compared with those not presenting with it. In such patients, a significantly decreased blood flow was also seen in the left upper frontal lobe and the bilateral parietal lobe. Xe-133 inhalation method should assist in evaluating brain function in schizophrenic patients, thus leading to the likelihood of developing a new treatment modality. (N.K.)

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

International Nuclear Information System (INIS)

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

1988-01-01

In 20 untreated patients with idiopathic or postmenopausal osteoporosis, kinetic studies of skeletal blood flow (using 18 F) and bone turnover (using 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 18 F correlated with an index of 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

Blood flow in healed and inflamed periodontal tissues of dogs

International Nuclear Information System (INIS)

Hock, J.M.; Kim, S.

1987-01-01

The objectives of this study were to determine if increased blood flow associated with gingivitis would decrease following resolution of gingival inflammation in dogs with periodontitis; if increased blood flow in inflamed gingiva was associated with changes in the blood flow of alveolar bone, and if blood flow in gingiva and alveolar bone increased if periodontitis was reactivated by ligating teeth. Regional blood flow was measured in dogs with pre-existing periodontitis, using radioisotope-labelled, plastic microspheres. In the first experiment on 4 adult Beagle dogs, teeth in the left jaws were treated to resolve the periodontitis, while teeth in the right jaws were not treated. Gingival and bone blood flow were measured after 12 wk. Blood flow was significantly (p 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. (author)

Rat muscle blood flows during high-speed locomotion

International Nuclear Information System (INIS)

Armstrong, R.B.; Laughlin, M.H.

1985-01-01

We previously studied blood flow distribution within and among rat muscles as a function of speed from walking (15 m/min) through galloping (75 m/min) on a motor-driven treadmill. The results showed that muscle blood flows continued to increase as a function of speed through 75 m/min. The purpose of the present study was to have rats run up to maximal treadmill speeds to determine if blood flows in the muscles reach a plateau as a function of running speed over the animals normal range of locomotory speeds. Muscle blood flows were measured with radiolabeled microspheres at 1 min of running at 75, 90, and 105 m/min in male Sprague-Dawley rats. The data indicate that even at these relatively high treadmill speeds there was still no clear evidence of a plateau in blood flow in most of the hindlimb muscles. Flows in most muscles continued to increase as a function of speed. These observed patterns of blood flow vs. running speed may have resulted from the rigorous selection of rats that were capable of performing the high-intensity exercise and thus only be representative of a highly specific population of animals. On the other hand, the data could be interpreted to indicate that the cardiovascular potential during exercise is considerably higher in laboratory rats than has normally been assumed and that inadequate blood flow delivery to the muscles does not serve as a major limitation to their locomotory performance

X-ray PIV measurement of blood flow in deep vessels of a rat: An in vivo feasibility study.

Science.gov (United States)

Park, Hanwook; Yeom, Eunseop; Lee, Sang Joon

2016-01-18

X-ray PIV measurement is a noninvasive approach to measure opaque blood flows. However, it is not easy to measure real pulsatile blood flows in the blood vessels located at deep position of the body, because the surrounding tissues significantly attenuate the contrast of X-ray images. This study investigated the effect of surrounding tissues on X-ray beam attenuation by measuring the velocity fields of blood flows in deep vessels of a live rat. The decrease in image contrast was minimized by employing biocompatible CO2 microbubbles as tracer particles. The maximum measurable velocity of blood flows in the abdominal aorta of a rat model was found through comparative examination between the PIV measurement accuracy and the level of image contrast according to the input flow rate. Furthermore, the feasibility of using X-ray PIV to accurately measure in vivo blood flows was demonstrated by determining the velocity field of blood flows in the inferior vena cava of a rat. This study may serve as a reference in conducting in vivo X-ray PIV measurements of pulsatile blood flows in animal disease models and investigating hemodynamic characteristics and circulatory vascular diseases.

Value of cerebral blood flow rate and regional oxygen consumption studies in cerebral ischaemia

Energy Technology Data Exchange (ETDEWEB)

Clanet, M

1987-06-18

Studies of experimentally-induced ischaemia have shown that the intensity of neuronal suffering is related to the fall in perfusion rate. Below a certain level, called functional threshold, cerebral function is reversibly altered, whereas at a lower level (tissue necrosis threshold) the damage inflicted on neurons is irreversible. Between these two thresholds lies a ''penumbra zone''. This concept of thresholds must be mitigated by 2 parameters: duration of ischaemia and selective vulnerability of the various structures affected. Variations in blood flow rate only indirectly affect the state of tissues. Techniques developed from positron emission tomography make it possible to evaluate the metabolic activity of brain tissue in vivo: oxygen consumption (CMRO/sub 2/), oxygen extraction (EO/sub 2/) and glucose consumption (CMRG) which are thus correlated to cerebral blood flow and cerebral blood volume, sometimes also to tissue pH. Normal relations between blood flow rate and metabolism may be altered. Misery perfusion reflects a fall in cerebral blood flow with an increase in EO/sub 2/ and often a decrease in CMRO/sub 2/, whereas luxury perfusion reflects an increase in cerebral blood flow rate with reduction of CMRO/sub 2/, EO/sub 2/ and CMRG. The type of alteration encountered in human ischaemia varies according to the nature of the accident: studies of transient accidents emphasize the different haemodynamic aspects of occlusion of the wider arteries. The metabolic and haemodynamic profiles of established ischaemic accidents vary according to their type and to the time of the study, reflecting the complexity of the physiopathological mechanisms involved; they are frequently associated with metabolic repercussions at a distance from the ischaemic focus, which supports the concept of diaschisis.

Value of cerebral blood flow rate and regional oxygen consumption studies in cerebral ischaemia

International Nuclear Information System (INIS)

Clanet, M.

1987-01-01

Studies of experimentally-induced ischaemia have shown that the intensity of neuronal suffering is related to the fall in perfusion rate. Below a certain level, called functional threshold, cerebral function is reversibly altered, whereas at a lower level (tissue necrosis threshold) the damage inflicted on neurons is irreversible. Between these two thresholds lies a ''penumbra zone''. This concept of thresholds must be mitigated by 2 parameters: duration of ischaemia and selective vulnerability of the various structures affected. Variations in blood flow rate only indirectly affect the state of tissues. Techniques developed from positron emission tomography make it possible to evaluate the metabolic activity of brain tissue in vivo: oxygen consumption (CMRO 2 ), oxygen extraction (EO 2 ) and glucose consumption (CMRG) which are thus correlated to cerebral blood flow and cerebral blood volume, sometimes also to tissue pH. Normal relations between blood flow rate and metabolism may be altered. Misery perfusion reflects a fall in cerebral blood flow with an increase in EO 2 and often a decrease in CMRO 2 , whereas luxury perfusion reflects an increase in cerebral blood flow rate with reduction of CMRO 2 , EO 2 and CMRG. The type of alteration encountered in human ischaemia varies according to the nature of the accident: studies of transient accidents emphasize the different haemodynamic aspects of occlusion of the wider arteries. The metabolic and haemodynamic profiles of established ischaemic accidents vary according to their type and to the time of the study, reflecting the complexity of the physiopathological mechanisms involved; they are frequently associated with metabolic repercussions at a distance from the ischaemic focus, which supports the concept of diaschisis [fr

Regulation of pulpal blood flow

International Nuclear Information System (INIS)

Kim, S.

1985-01-01

The regulation of blood flow of the dental pulp was investigated in dogs and rats anesthetized with sodium pentobarbital. Pulpal blood flow was altered by variations of local and systemic hemodynamics. Macrocirculatory blood flow (ml/min/100 g) in the dental pulp was measured with both the 133 Xe washout and the 15-microns radioisotope-labeled microsphere injection methods on the canine teeth of dogs, to provide a comparison of the two methods in the same tooth. Microcirculatory studies were conducted in the rat incisor tooth with microscopic determination of the vascular pattern, RBC velocity, and intravascular volumetric flow distribution. Pulpal resistance vessels have alpha- and beta-adrenergic receptors. Activation of alpha-receptors by intra-arterial injection of norepinephrine (NE) caused both a reduction in macrocirculatory Qp in dogs and decreases in arteriolar and venular diameters and intravascular volumetric flow (Qi) in rats. These responses were blocked by the alpha-antagonist PBZ. Activation of beta-receptors by intra-arterial injection of isoproterenal (ISO) caused a paradoxical reduction of Qp in dogs. In rats, ISO caused a transient increase in arteriolar Qi followed by a flow reduction; arteriolar dilation was accompanied by venular constriction. These macrocirculatory and microcirculatory responses to ISO were blocked by the alpha-antagonist propranolol

Prediction of blood pressure and blood flow in stenosed renal arteries using CFD

Science.gov (United States)

Jhunjhunwala, Pooja; Padole, P. M.; Thombre, S. B.; Sane, Atul

2018-04-01

In the present work an attempt is made to develop a diagnostive tool for renal artery stenosis (RAS) which is inexpensive and in-vitro. To analyse the effects of increase in the degree of severity of stenosis on hypertension and blood flow, haemodynamic parameters are studied by performing numerical simulations. A total of 16 stenosed models with varying degree of stenosis severity from 0-97.11% are assessed numerically. Blood is modelled as a shear-thinning, non-Newtonian fluid using the Carreau model. Computational Fluid Dynamics (CFD) analysis is carried out to compute the values of flow parameters like maximum velocity and maximum pressure attained by blood due to stenosis under pulsatile flow. These values are further used to compute the increase in blood pressure and decrease in available blood flow to kidney. The computed available blood flow and secondary hypertension for varying extent of stenosis are mapped by curve fitting technique using MATLAB and a mathematical model is developed. Based on these mathematical models, a quantification tool is developed for tentative prediction of probable availability of blood flow to the kidney and severity of stenosis if secondary hypertension is known.

Brain blood flow studies with single photon emission computed tomography in patients with plateau waves

International Nuclear Information System (INIS)

Hayashi, Minoru; Kobayashi, Hidenori; Kawano, Hirokazu; Handa, Yuji; Noguchi, Yoshiyuki; Shirasaki, Naoki; Hirose, Satoshi

1986-01-01

The authors studied brain blood flow with single photon emission computed tomography (SPECT) in two patients with plateau waves. The intracranial pressure and blood pressure were also monitored continuously in these patients. They included one patient with brain-tumor (rt. sphenoid ridge meningioma) and another with hydrocephalus after subarachnoid hemorrhage due to rupture of lt. internal carotid aneurysm. The intracranial pressure was monitored through an indwelling ventricular catheter attached to a pressure transducer. The blood pressure was recorded through an intraarterial catheter placed in the dorsalis pedis artery. Brain blood flow was studied with Headtome SET-011 (manufactured by Shimazu Co., Ltd.). For this flow measurement study, an intravenous injection of Xenon-133 of about 30 mCi was given via an antecubital vein. The position of the slice for the SPECT was selected so as to obtain information not only from the cerebral hemisphere but also from the brain stem : a cross section 25 deg over the orbito-meatal line, passing through the inferior aspect of the frontal horn, the basal ganglia, the lower recessus of the third ventricle and the brain stem. The results indicated that, in the cerebral hemisphere, plateau waves were accompanied by a decrease in blood flow, whereas, in the brain stem, the blood flow showed little change during plateau waves as compared with the interval phase between two plateau waves. These observations may explain why there is no rise in the blood pressure and why patients are often alert during plateau waves. (author)

Postradiation regional cerebral blood flow in primates

International Nuclear Information System (INIS)

Cockerham, L.G.; Cerveny, T.J.; Hampton, J.D.

1986-01-01

Early transient incapacitation (ETI) is the complete cessation of performance during the first 30 min after radiation exposure and performance decrement (PD) is a reduction in performance at the same time. Supralethal doses of radiation have been shown to produce a marked decrease in regional cerebral blood flow in primates concurrent with hypotension and a dramatic release of mast cell histamine. In an attempt to elucidate mechanisms underlying the radiation-induced ETI/PD phenomenon and the postradiation decrease in cerebral blood flow, primates were exposed to 100 Gy (1 Gy = 100 rads), whole-body, gamma radiation. Pontine and cortical blood flows were measured by hydrogen clearance, before and after radiation exposure. Systemic blood pressures were determined simultaneously. Systemic arterial histamine levels were determined preradiation and postradiation. Data obtained indicated that radiated animals showed a decrease in blood flow of 63% in the motor cortex and 51% in the pons by 10 min postradiation. Regional cerebral blood flow of radiated animals showed a slight recovery 20 min postradiation, followed by a fall to the 10 min nadir by 60 min postradiation. Immediately, postradiation systemic blood pressure fell 67% and remained at that level for the remainder of the experiment. Histamine levels in the radiated animals increased a hundredfold 2 min postradiation. This study indicates that regional cerebral blood flow decreases postradiation with the development of hypotension and may be associated temporally with the postradiation release of histamine

Aging, regional cerebral blood flow, and neuropsychological functioning

International Nuclear Information System (INIS)

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

1984-01-01

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

Investigation of intrarenal blood flow and urine flow aspects by scintillation camera

International Nuclear Information System (INIS)

Kawamura, J.; Hosokawa, S.; Yoshida, O.; Ishii, Y.; Torizuka, K.

1977-01-01

In order to clarify intrarenal dynamic processes related to regional distribution in patients with unilateral renal disease, two radioactive tracers, 133 Xe and /sup 99m/Tc-diethylenetriaminepentaacetic acid (/sup 99m/Tc-DTPA) were introduced into a renal artery and intrarenal blood flow and urine flow aspects were observed by scintillation camera. Cortical blood flow decreased and medullary blood flow relatively increased with the advance of renal damage. Urine flow curve from normal cortex showed two phasic patterns. One early phase might correspond to the appearance of the tracer through the proximal tubule and a second phase might correspond to the appearance of the tracer through the loop of Henle to the distal tubule. Under mannitol diuresis, two phasic urine flow curves from the cortex became obscured and the peak time of pelvic curve shifted to the earlier period. These studies were considered to be useful in evaluating unilateral renal function and might offer a good insight for intrarenal physiology concerning blood flow as well as urine flow

Relationship Between Blood Flow and Performance Recovery: A Randomized, Placebo-Controlled Study.

Science.gov (United States)

Borne, Rachel; Hausswirth, Christophe; Bieuzen, François

2017-02-01

To investigate the effect of different limb blood-flow levels on cycling-performance recovery, blood lactate concentration, and heart rate. Thirty-three high-intensity intermittent-trained athletes completed two 30-s Wingate anaerobic test sessions, 3 × 30-s (WAnT 1-3) and 1 × 30-s (WAnT 4), on a cycling ergometer. WAnT 1-3 and WAnT 4 were separated by a randomly assigned 24-min recovery intervention selected from among blood-flow restriction, passive rest, placebo stimulation, or neuromuscular electrical-stimulation-induced blood flow. Calf arterial inflow was measured by venous occlusion plethysmography at regular intervals throughout the recovery period. Performance was measured in terms of peak and mean power output during WAnT 1 and WAnT 4. After the recovery interventions, a large (r = .68 [90% CL .42; .83]) and very large (r = .72 (90% CL .49; .86]) positive correlation were observed between the change in calf arterial inflow and the change in mean and peak power output, respectively. Calf arterial inflow was significantly higher during the neuromuscular-electrical-stimulation recovery intervention than with the blood-flow-restriction, passive-rest, and placebo-stimulation interventions (P .05). No recovery effect was linked to heart rate or blood lactate concentration levels. For the first time, these data support the existence of a positive correlation between an increase in blood flow and performance recovery between bouts of high-intensity exercise. As a practical consideration, this effect can be obtained by using neuromuscular electrical stimulation-induced blood flow since this passive, simple strategy could be easily applied during short-term recovery.

Measurement of Finger Blood Flow in Raynauds Phenomenon by Radionuclide Angiography

International Nuclear Information System (INIS)

Lim, Sang Moo; Chung, June Key; Lee, Myung Chul; Kim, Sang Joon; Choi, Sung Jae; Koh, Chang Soon

1987-01-01

In Raynauds phenomenon, the authors measured finger blood flow after ice water exposure by analyzing the time activity curve of radionuclide angiography on both hands. The results were as follows: 1) The digital blood flow did not decrease after ice water exposure in normal subjects. 2) In the patients with Raynauds phenomenon, there were two groups: the one had decreased digital blood flow after cold exposure, and the other had paradoxically increased digital blood flow after cold exposure. 3) There was no difference in the digital blood flow of hand in room temperature between the normal and the patients with reduced digital blood flow after cold exposure, but the digital blood flow of the hand in room temperature was markedly reduced in the patients with paradoxically increased flow after cold exposure. 4) In the static image the difference was not significant in comparison with the dynamic study, because it represents pooling of the blood in the vein rather than flow. 5) After the treatment with nifedipine, the digital blood flow increased. In conclusion, the radionuclide angiography was useful in measuring the digital blood flow in Raynauds phenomenon, and further studies with various drugs is expected.

Regional cerebral blood flow in schizophrenia

International Nuclear Information System (INIS)

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

1982-01-01

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

Regional cerebral blood flow in schizophrenia

Energy Technology Data Exchange (ETDEWEB)

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

1982-10-01

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.

Influence of restoration adjustments on prefrontal blood flow: A simplified NIRS preliminary study.

Science.gov (United States)

Sasaguri, Kenichi; Otsuka, Takero; Tsunashima, Hiroyuki; Shimazaki, Tateshi; Kubo, Kin-Ya; Onozuka, Minoru

The aim of this study was to examine, after setting several restorations, the influence of adjusted occlusal interference during gum chewing on blood flow in the prefrontal area as determined using near-infrared spectroscopy. The physiological rate was assessed using a visual analog scale (VAS) questionnaire. We selected 16 patients who desired prosthetic restorative treatment on the lateral dentition, and eight healthy volunteers. Subjects were divided into three eight-person groups. One group received restorations on the premolar area (PA), another group received restorations on the molar area (MA), and the control group (CT) received no prosthetic restorations. The spectroscope was fastened to the frontal region of the head after placement of the final restoration, but before adjustment. Pre-adjustment (first gum chewing for CT) blood flow in the prefrontal cortex was measured during gum chewing. Blood flow was again measured during gum chewing after the restoration (second gum chewing for CT) had been adjusted in accordance with the subjective assessment of the patient while wearing the device. The VAS provided quantification of comfort during gum chewing before and after restoration adjustment. For the PA and MA groups, adjusting restorations decreased discomfort significantly during gum chewing. Moreover, in the MA group, prefrontal blood flow was significantly reduced, and blood flow correlated with discomfort. Activation of the prefrontal area may provide an objective criterion for judging the functionality of occlusion after prosthetic occlusal reconstruction and/or orthodontics.

Study of intracardiac blood flow by MRI using gradient echo method

Energy Technology Data Exchange (ETDEWEB)

Ohnishi, Shusaku; Fukui, Sugao; Atsumi, Chisato; Morita, Ruriko; Kusuoka, Hideo; Fujii, Kenshi; Kitabatake, Akira; Takizawa, Osamu.

1988-06-01

In order to investigate the possibility of MR imaging for the evaluation of intracardiac blood flow especially valvular regurgitant flow, we obtained MR images using a 1.5 tesla superconductive magnet system (Siemens Medical) in 3 healthy volunteers, 3 patients with hypertrophic cardiomyopathy and 8 patients with valvular heart disease. Rapid FLASH (Fast Low-Angle Shot) imaging technique was applied to collect 11 time frames per section throughout one cardiac cycle in axial, coronal, saggital and oblique sections. Then these sequential frames were displayed in a cine mode on CRT. (1) Intracardiac and intravascular blood flow were visualized with high signal intensity in each frame and cardiac structures such as atria, ventricles, and aorta were also identified in all subjects. (2) Ventricular ejection flow was easily visualized in coronal section as the signal loss in the ascending aorta. Ventricularfilling was visualized in axial and oblique sections as the high signal influx of atrial blood into the ventricle. (3) In 3 patients with aortic regurgitation, regurgitant flow was detected during diastole as the teardrop shaped signal loss originating from aortic valve cusps. (4) Both mitral and tricuspid regurgitant flow were detected during systole as the signal loss in atrium in axial and oblique sections in 2 patients with MR and 2 patients with TR. (5) Pulmonary regurgitant flow was observed in oblique section along the long axis of right ventricular outflow tract. These results indicate that intracardiac forward and regurgitant flow could be identified with rapid FLASH imaging in normal subjects and in patients with valvular heart diseases, and cine mode MR imaging is a useful tool for the evaluation of intracardiac blood flow.

The role of blood flow in chronic duodenal ulcer

Energy Technology Data Exchange (ETDEWEB)

Gompertz, R.H.K.; Mathie, R.T.; Michalowski, A.S.; Spencer, J.; Baron, J.H.; Williamson, R.C.N.

1996-01-01

Changes in gastroduodenal blood flow have been implicated in the pathogenesis of duodenal ulcer. The authors have studied duodenal blood flow during the development of an acute to chronic duodenal ulcer by using the abscopal model, in which ulcers are generated as an indirect effect of lower mediastinal irradiation. Female CFLP mice were randomly allocated to one of three groups. Irradiated ``controls`` received 18 Gy 250 kV X-rays to the upper mediastinum. The lower mediastinum group received the same dose of irradiation, which has been shown to induce typical chronic duodenal ulcers in 45% of animals so treated. Animals were studied by means of radiolabelled microspheres 3 or 7 days later. Proximal duodenal blood flow specifically was reduced by 32% in the lower mediastinum group compared with irradiated controls at 7 days. There was no significant difference in blood flow to the stomach and to the distal duodenum. The decrease in proximal duodenal blood flow in the lower mediastinum group did not differ in the five animals that developed ulcer compared with the seven that did not. Although, there is an overall decrease in duodenal blood flow associated with chronic duodenal ulcer, reduced blood flow may not explain individual susceptibility to ulceration. 21 refs., 1 fig., 2 tabs.

Measurement of organ blood flow using tritiated water. II. Uterine blood flow in conscious pregnant ewes

International Nuclear Information System (INIS)

Brown, B.W.; Oddy, V.H.; Jones, A.W.

1982-01-01

Total uterine blood flow was measured with a tritiated water (TOH) diffusion method and with radioactive microspheres in six, conscious, pregnant ewes. With continuous infusion of TOH, equilibrium between the TOH concentration in utero-ovarian venous blood and arterial blood was attained within 50 min of the start of the infusion. The concentration of TOH in uterine and foetal tissue and in foetal blood water was the same as that in uterine venous water by 40 min; at this time, the concentration of TOH in the water of amniotic and allantoic fluids was 96% of that in uterine venous blood water. Estimates of total uterine blood flow obtained using TOH were highly correlated with those obtained with microspheres and the corresponding mean flow values obtained with the two techniques did not significantly differ. The percentage of the total uterine blood flow passing through arteriovenous anastomoses ranged from 1.4 to 3.3%

Left coronary arterial blood flow: Noninvasive detection by Doppler US

International Nuclear Information System (INIS)

Gramiak, R.; Holen, J.; Moss, A.J.; Gutierrez, O.H.; Picone, A.L.; Roe, S.A.

1986-01-01

Continuous wave (CW) and pulsed Doppler ultrasound studies with spectral analysis were used to detect the left coronary arterial blood flow in patients who were undergoing routine echocardiography. The pulmonary artery is a stable ultrasonic landmark from which detection of the blood flow can be effected. The left coronary artery can be distinguished by its blood flow toward the cardiac apex and by specific, functional flow features. Flow patterns vary among the left main, circumflex, and anterior descending arteries; patterns also vary with respiration cycles. In the present study, coronary arterial blood flow was detected in 58 of 70 patients (83%). Findings were validated by selectively injecting an agitated saline contrast medium into the left coronary artery and, in another study, by comparing human Doppler phasic flow waveforms with electromagnetic flowmeter recordings obtained in dogs

Trial on MR portal blood flow measurement with phase contrast technique

International Nuclear Information System (INIS)

Tsunoda, Masatoshi; Kimoto, Shin; Togami, Izumi

1991-01-01

Portal blood flow measurement is considered to be important for the analysis of hemodynamics in various liver diseases. The Doppler ultrasound method has been used extensively during the past several years for measuring portal blood flow, as a non-invasive method. However, the Doppler ultrasound technique do not allow the portal blood flow to be measured in cases of obesity, with much intestinal gas, and so on. In this study, we attempted to measure the blood flow in the main trunk of portal vein as an application of MR phase contrast technique to the abdominal region. In the flow phantom study, the flow volumes and the velocities measured by phase contrast technique showed a close correlation with those measured by electromagnetic flowmeter. In the clinical study with 10 healthy volunteers, various values of portal blood flow were obtained. Mean portal blood flow could be measured within the measuring time (about 8 minutes) under natural breathing conditions. Phase contrast technique is considered to be useful for the non-invasive measurement of portal blood flow. (author)

Comparison of blood flow and cell function in ischemic skin flaps

International Nuclear Information System (INIS)

Bean, D.; Rees, R.S.; O'Leary, J.P.; Lynch, J.B.

1984-01-01

Cellular function and blood flow in acute, steroid-treated, and surgically delayed random skin flaps have been examined. In these studies, the period following flap elevation could be divided into early (0-2 hr), intermediate (4-6 hr), and late (12 hr) periods of ischemia, based on the cutaneous blood flow and cellular function measured by thallium-201 uptake. There was a close correlation between blood flow and cellular function during the early period of ischemia which became worse with time. Blood flow studies demonstrated a significant difference between the early and intermediate periods of ischemia which was abolished by surgical delay. Improvement in cellular function was accomplished by improved blood flow in the surgically delayed flaps, while steroid-treated flaps enhanced cellular metabolism by another mechanism. Cellular function approximated blood flow during the early and immediate period of ischemia. Steroids may augment cellular function without improving blood flow, while surgical delay improves cellular function by improving blood flow

Studies on age-related changes, regional and bilateral differences in the skin blood flow

International Nuclear Information System (INIS)

Park, Myung-Wook

1992-01-01

Xenon-133 clearance method was used to determine skin blood flow at different sites. The correlation between skin blood flow in the deltoid region and age was examined. In addition, regional and bilateral differences in skin blood flow were examined. The subjects were 60 men. They ranged in age from 23 to 72 years with a mean of 53.3±10.95. Fifty μCi of xenon-133 dissolved in 0.1 ml of sterile distilled water was injected into the skin area. The clearance curve over the skin was recorded for 30 minutes by a scintillation counter. Skin blood flow in the deltoid region decreased significantly with aging. Dorsal skin blood flow in the hands and feet were significantly lower than the deltoid region. Regarding skin blood flow in the deltoid regions, there was significantly bilateral difference. In the hands and feet, the dorsal skin was bilaterally nearly equal. In view of regional hemodynamics in the skin, the conditions for random-pattern skin flap and wound healing were unfavorable in the elderly as compared with younger persons. Skin blood flow decreased gradually from the upper part of the body to the lower part of the body. In skin blood flow in the dorsal skin of the hands and feet, no bilateral difference was observed. (N.K.)

Comparative study of Newtonian physiological blood flow through normal and stenosed carotid artery

Science.gov (United States)

Rahman, Mohammad Matiur; Hossain, Md. Anwar; Mamun, Khairuzzaman; Akhter, Most. Nasrin

2017-06-01

A numerical simulation is performed to investigate Newtonian physiological flows behavior on three dimensional idealized carotid artery (CA) and single stenosed (75% by area) carotid artery(SCA). The wall vessel is set as rigid during simulation. Bifurcated blood vessel are simulated by using three-dimensional flow analysis. Physiological and parabolic velocity profiles are set out to fix the conditions of inlet boundaries of artery. In other hand, physiological waveform is an important part of compilation and it is successfully done by utilization of Fourier series having sixteen harmonics. The investigation has a Reynolds number range of 94 to 1120. Low Reynolds number k — ω model has been used as governing equation. The investigation has been carried out to characterize the flow behavior of blood in two geometry, namely, (i) Normal carotid artery (CA) and (ii) Stenosed carotid artery (SCA). The Newtonian model has been used to study the physics of fluid. The findings of the two models are thoroughly compared in order to observe there behavioral sequence of flows. The numerical results were presented in terms of velocity, pressure, wall shear stress distributions and cross sectional velocities as well as the streamlines contour. Stenosis disturbs the normal pattern of blood flow through the artery as reduced area. At stenosis region velocity and peak Reynolds number rapidly increase and Reynolds number reach transitional and turbulent region. These flow fluctuation and turbulence have bad effect to the blood vessel which makes to accelerate the progress of stenosis.

Spiral blood flow in aorta-renal bifurcation models.

Science.gov (United States)

Javadzadegan, Ashkan; Simmons, Anne; Barber, Tracie

2016-01-01

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

Dynamic Infrared Thermography Study of Blood Flow Relative to Lower Limp Position

Science.gov (United States)

Stathopoulos, I.; Skouroliakou, K.; Michail, C.; Valais, I.

2015-09-01

Thermography is an established method for studying skin temperature distribution. Temperature distribution on body surface is influenced by a variety of physiological mechanisms and has been proven a reliable indicator of various physiological disorders. Blood flow is an important factor that influences body heat diffusion and skin temperature. In an attempt to validate and further elucidate thermal models characterizing the human skin, dynamic thermography of the lower limp in horizontal and vertical position was performed, using a FLIR T460 thermographic camera. Temporal variation of temperature was recorded on five distinct points of the limp. Specific points were initially cooled by the means of an ice cube and measurements of the skin temperature were obtained every 30 seconds as the skin temperature was locally reduced and afterwards restored at its initial value. The return to thermal balance followed roughly the same pattern for all points of measurement, although the heating rate was faster when the foot was in horizontal position. Thermal balance was achieved faster at the spots that were positioned on a vein passage. Our results confirm the influence of blood flow on the thermal regulation of the skin. Spots located over veins exhibit different thermal behaviour due to thermal convection through blood flow. Changing the position of the foot from vertical to horizontal, effectively affects blood perfusion as in the vertical position blood circulation is opposed by gravity.

Blood flow in healed and inflamed periodontal tissues of dogs

Energy Technology Data Exchange (ETDEWEB)

Hock, J.M.; Kim, S.

1987-01-01

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

Low cerebral blood flow in hypotensive perinatal distress

DEFF Research Database (Denmark)

Lou, H C; Lassen, N A; Friis-Hansen, B

1977-01-01

was used for the cerebral blood flow measurements. The study confirmed that perinatal distress may be associated with low arterial blood pressure, and it was shown that cerebral blood flow is very low, 20 ml/100 g/min or less, in hypotensive perinatal distress. It is concluded that cerebral ischaemia plays...... a crucial role in the development of perinatal hypoxic brain injury....

Decreased cerebral blood flow and prognosis of Alzheimer's disease. A multicenter HMPAO-SPECT study

International Nuclear Information System (INIS)

Nishimura, Tsunehiko; Hashikawa, Kazuo; Fukuyama, Hidenao

2007-01-01

The purpose of this study was to determine the usefulness of brain perfusion single photon emission computed tomography (SPECT) for evaluating the severity and progression of Alzheimer's disease (AD). Eighty-four AD patients were included. At entry, 99m Tc-HMPAO-SPECT, the Mini Mental State Examination (MMSE), Mental Function Impairment Scale (MENFIS), and the Raven Colored Progression Matrix (RCPM) were performed for all 84 patients. During the follow-up periods, two individual MMSE evaluations in 34 patients, two MENFIS evaluations in 30 patients, and two RCPM evaluations in 20 patients were performed. Based on the regions of decreased cerebral blood flow demonstrated on three-dimensional stereotactic surface projection (3D-SSP) images of SPECT, the cases were classified as type A (no decrease), type B (decreased blood flow in the parietal or temporal lobe), type C (decreased blood flow in the frontal lobe and parietal or temporal lobe), type Pc (decreased blood flow in posterior cingulate gyrus only), and ''other types''. The types of decreased blood flow, scores on neuropsychological evaluations, and symptom progression were analyzed. The MENFIS, MMSE, and RCPM scores were poorest in type C patients at entry. The degree of decrease of these scores during the follow-up periods was also greatest in type C. The greatest difference between patients with and without rapid progression in SPECT data of the mild AD patients (MMSE score≥24) was in the frontal lobe. Decreased blood flow in the frontal lobe of AD patients is correlated not only with reduced cognitive function at the time of the evaluation but with rapid progression in the subsequent clinical course. (author)

Our experience of blood flow measurements using radioactive tracers

International Nuclear Information System (INIS)

Danet, Bernard.

1974-01-01

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

Nutrient and nonnutrient renal blood flow

International Nuclear Information System (INIS)

Young, J.S.; Passmore, J.C.; Hartupee, D.A.; Baker, C.H.

1990-01-01

The role of prostaglandins in the distribution of total renal blood flow (TRBF) between nutrient and nonnutrient compartments was investigated in anesthetized mongrel dogs. Renal blood flow distribution was assessed by the xenon 133 freeze-dissection technique and by rubidium 86 extraction after ibuprofen treatment. Ibuprofen (13 mg/kg) significantly decreased TRBF by 16.3% +/- 1.2% (mean +/- SEM electromagnetic flow probe; p less than 0.005), but did not alter blood flows to the outer cortex (3.7 vs 4.3 ml/min per gram), the inner cortex (2.6 vs 2.7 ml/min per gram), and the other medulla (1.5 vs 1.5 ml/min per gram), which suggests a decrease in nonnutrient flow. In a separate group of animals the effect of reduced blood flow on the nutrient and nonnutrient components was determined by mechanically reducing renal arterial blood flow by 48%. Unlike the ibuprofen group, nutrient blood flows were proportionally reduced with the mechanical decrease in TRBF in the outer cortex (1.9 ml/min per gram, p less than 0.05), the inner cortex (1.4 ml/min per gram, p less than 0.05), and the outer medulla (0.8 ml/min per gram, p less than 0.01). These results indicate no shift between nutrient and nonnutrient compartments. Nutrient and nonnutrient renal blood flows of the left kidney were also determined by 86Rb extraction. After ibuprofen treatment, nonextracted 86Rb decreased to 12.1% from the control value of 15.6% (p less than 0.05). Mechanical reduction of TRBF did not significantly decrease the proportion of unextracted 86Rb (18.7%)

The effect of sympathectomy on bone blood flow in man

International Nuclear Information System (INIS)

Lahtinen, T.; Alhava, E.M.; Hyoedynmaa, S.; Hendolin, H.; Oksala, I.

1982-01-01

The effect of lumbar sympathectomy on bone blood flow was measured in seven patients with a Xe-133 washout method. On the third postoperative day there was a significant increase of blood flow in the proximal femur and a slight increase in the proximal tibia. Two months after the operation blood flow in the proximal part of the femur was no more significantly increased but in the proximal tibia there was a significant increase. The study suggests that the positive effect of sympathectomy on bone blood flow may be of value in cases where the increase of blood flow to peripheral bones is required

Modified Beer-Lambert law for blood flow.

Science.gov (United States)

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

2014-11-01

We develop and validate a Modified Beer-Lambert law for blood flow based on diffuse correlation spectroscopy (DCS) measurements. The new formulation enables blood flow monitoring from temporal intensity autocorrelation function data taken at single or multiple delay-times. Consequentially, the speed of the optical blood flow measurement can be substantially increased. The scheme facilitates blood flow monitoring of highly scattering tissues in geometries wherein light propagation is diffusive or non-diffusive, and it is particularly well-suited for utilization with pressure measurement paradigms that employ differential flow signals to reduce contributions of superficial tissues.

Regional cerebral blood flow in focal cortical epilepsy

DEFF Research Database (Denmark)

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

1976-01-01

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

Noxious heat and scratching decrease histamine-induced itch and skin blood flow.

Science.gov (United States)

Yosipovitch, Gil; Fast, Katharine; Bernhard, Jeffrey D

2005-12-01

The aim of this study was to assess the effect of thermal stimuli or distal scratching on skin blood flow and histamine-induced itch in healthy volunteers. Twenty-one healthy volunteers participated in the study. Baseline measurements of skin blood flow were obtained on the flexor aspect of the forearm. These measurements were compared with skin blood flow after various stimuli: heating the skin, cooling the skin, noxious cold 2 degrees C, noxious heat 49 degrees C, and scratching via a brush with controlled pressure. Afterwards histamine iontophoresis was performed and skin blood flow and itch intensity were measured immediately after the above-mentioned stimuli. Scratching reduced mean histamine-induced skin blood flow and itch intensity. Noxious heat pain increased basal skin blood flow but reduced histamine-induced maximal skin blood flow and itch intensity. Cold pain and cooling reduced itch intensity, but neither affected histamine-induced skin blood flow. Sub-noxious warming the skin did not affect the skin blood flow or itch intensity. These findings suggest that heat pain and scratching may inhibit itch through a neurogenic mechanism that also affects skin blood flow.

Effects of Red Blood Cell Aggregation on the Apparent Viscosity of Blood Flow in Tubes.

Science.gov (United States)

Hitt, Darren L.; Lowe, Mary L.

1996-11-01

In arterioles and venules (20-200μ diameter), the low shear rates enable red blood cells to form aggregate structures of varying sizes and morphology. The size and distribution of the aggregates affect the flow impedance within a microvascular network; this effect may be characterized by an "apparent viscosity". In this study, we measure the apparent viscosity of blood flow in 50μ glass tubes as a function of shear rate and red blood cell volume fraction (hematocrit); for a fixed tube geometry and an imposed flow rate, the viscosity is determined by measuring the pressure drop across the tube. To correlate the apparent viscosity with the size and spatial distribution of the aggregates in the flow, video images of the flow are recorded and analyzed using power spectral techniques. Pig blood and sheep blood are used as the models for aggregating and non-aggregating blood, respectively. Supported by NSF PFF Award CTS-9253633

The effect of ventricular assist devices on cerebral blood flow and blood pressure fractality

International Nuclear Information System (INIS)

Bellapart, Judith; Fraser, John F; Chan, Gregory S H; Tzeng, Yu-Chieh; Ainslie, Philip N; Dunster, Kimble R; Barnett, Adrian G; Boots, Rob

2011-01-01

Biological signals often exhibit self-similar or fractal scaling characteristics which may reflect intrinsic adaptability to their underlying physiological system. This study analysed fractal dynamics of cerebral blood flow in patients supported with ventricular assist devices (VAD) to ascertain if sustained modifications of blood pressure waveform affect cerebral blood flow fractality. Simultaneous recordings of arterial blood pressure and cerebral blood flow velocity using transcranial Doppler were obtained from five cardiogenic shock patients supported by VAD, five matched control patients and five healthy subjects. Computation of a fractal scaling exponent (α) at the low-frequency time scale by detrended fluctuation analysis showed that cerebral blood flow velocity exhibited 1/f fractal scaling in both patient groups (α = 0.95 ± 0.09 and 0.97 ± 0.12, respectively) as well as in the healthy subjects (α = 0.86 ± 0.07). In contrast, fluctuation in blood pressure was similar to non-fractal white noise in both patient groups (α = 0.53 ± 0.11 and 0.52 ± 0.09, respectively) but exhibited 1/f scaling in the healthy subjects (α = 0.87 ± 0.04, P < 0.05 compared with the patient groups). The preservation of fractality in cerebral blood flow of VAD patients suggests that normal cardiac pulsation and central perfusion pressure changes are not the integral sources of cerebral blood flow fractality and that intrinsic vascular properties such as cerebral autoregulation may be involved. However, there is a clear difference in the fractal scaling properties of arterial blood pressure between the cardiogenic shock patients and the healthy subjects

A study of intracardiac blood flow by MRI using gradient echo method

International Nuclear Information System (INIS)

Ohnishi, Shusaku; Fukui, Sugao; Atsumi, Chisato; Morita, Ruriko; Kusuoka, Hideo; Fujii, Kenshi; Kitabatake, Akira; Takizawa, Osamu.

1988-01-01

In order to investigate the possibility of MR imaging for the evaluation of intracardiac blood flow especially valvular regurgitant flow, we obtained MR images using a 1.5 tesla superconductive magnet system (Siemens Medical) in 3 healthy volunteers, 3 patients with hypertrophic cardiomyopathy and 8 patients with valvular heart disease. Rapid FLASH (Fast Low-Angle Shot) imaging technique was applied to collect 11 time frames per section throughout one cardiac cycle in axial, coronal, saggital and oblique sections. Then these sequential frames were displayed in a cine mode on CRT. (1) Intracardiac and intravascular blood flow were visualized with high signal intensity in each frame and cardiac structures such as atria, ventricles, and aorta were also identified in all subjects. (2) Ventricular ejection flow was easily visualized in coronal section as the signal loss in the ascending aorta. Ventricularfilling was visualized in axial and oblique sections as the high signal influx of atrial blood into the ventricle. (3) In 3 patients with aortic regurgitation, regurgitant flow was detected during diastole as the teardrop shaped signal loss originating from aortic valve cusps. (4) Both mitral and tricuspid regurgitant flow were detected during systole as the signal loss in atrium in axial and oblique sections in 2 patients with MR and 2 patients with TR. (5) Pulmonary regurgitant flow was observed in oblique section along the long axis of right ventricular outflow tract. These results indicate that intracardiac forward and regurgitant flow could be identified with rapid FLASH imaging in normal subjects and in patients with valvular heart diseases, and cine mode MR imaging is a useful tool for the evaluation of intracardiac blood flow. (author)

A study of the acute effect of smoking on cerebral blood flow using 99mTc-ECD SPET

International Nuclear Information System (INIS)

Yamamoto, Yuka; Nishiyama, Yoshihiro; Monden, Toshihide; Satoh, Katashi; Ohkawa, Motoomi

2003-01-01

Cigarette smoking is known to be associated with atherosclerosis, is an important risk factor for stroke and has other serious effects. The aim of this study was to evaluate the acute effect of cigarette smoking on cerebral blood flow using statistical parametric mapping (SPM). Ten healthy volunteers with a smoking habit were studied using technetium-99m-labelled ethylcysteinate dimer single-photon emission tomography (SPET). We evaluated the regional cerebral blood flow under the smoking and resting states. The regional cerebral blood flow on smoking-activated SPET was significantly decreased in the whole brain as compared with that on resting SPET. Our findings therefore suggest that one of the acute effects of cigarette smoking is to induce a diffuse decrease in cerebral blood flow. (orig.)

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

1997-03-01

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)

Abnormality in cerebellar blood flow in solo vertigo patients

International Nuclear Information System (INIS)

Nagahori, Takeshi; Nishijima, Michiharu; Endo, Shunro; Takaku, Akira

1997-01-01

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)

Blood cell interactions and segregation in flow.

Science.gov (United States)

Munn, Lance L; Dupin, Michael M

2008-04-01

For more than a century, pioneering researchers have been using novel experimental and computational approaches to probe the mysteries of blood flow. Thanks to their efforts, we know that blood cells generally prefer to migrate to the axis of flow, that red and white cells segregate in flow, and that cell deformability and their tendency to reversibly aggregate contribute to the non-Newtonian nature of this unique fluid. All of these properties have beneficial physiological consequences, allowing blood to perform a variety of critical functions. Our current understanding of these unusual flow properties of blood have been made possible by the ingenuity and diligence of a number of researchers, including Harry Goldsmith, who developed novel technologies to visualize and quantify the flow of blood at the level of individual cells. Here we summarize efforts in our lab to continue this tradition and to further our understanding of how blood cells interact with each other and with the blood vessel wall.

Intrinsic regulation of blood flow in adipose tissue

DEFF Research Database (Denmark)

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

1976-01-01

Previous studies on intact human subcutaneous tissue have shown, that blood flow remains constant during minor changes in perfusion pressure. This so-called autoregulatory response has not been demonstrable in isolated preparations of adipose tissue. In the present study on isolated, denervated...... 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...... vasoconstriction with pronounced flow reduction. These two reactions may be important for local regulation of blood flow in subcutaneous tissue during orthostatic changes in arterial and venous pressure. It is concluded that the response in adipose tissue to changes in arterial pressure (autoregulation), venous...

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

2006-01-01

-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...... 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...

Corticosteroid Reduces Blood Flow to Femoral Heads in Rabbits.

Science.gov (United States)

Hou, S.M.; Liu, T.K.; Kao, M.C.

1994-12-01

Avascular necrosis of the femoral head is one of the common problems in orthopedic practice in Taiwan. The subchondral bone loses its blood supply which weakens its biomechanical support. Steroid overuse is one of many possible etiologies in reducing blood flow to the femoral head. Laser Doppler velocimeter is a precise monitor of regional blood flow of bone which is expressed in perfusion units (PU). In the control group the rabbits were injected with normal saline and there were no statistical differences between blood flow to the right hip (39.26 +/- 5.64 PU) and left hip (38.58 +/- 4.35 PU). In group B a weekly injection of methylprednisolone into rabbits for 6 weeks demonstrated the reduction of blood flow of femoral head (24.74 +/- 3.13 PU) by the laser Doppler velocimeter. The flow decreased further (15.93 +/- 2.33 PU) by 12 weeks of steroid treatment. In group C after a weekly injection of steroid for 6 weeks the flow became 31.63 +/- 4.79 PU. The steroid was then discontinued for 3 weeks and the flow was 34.6 +/- 1.34 PU. In group D the blood flow was 25.89 +/- 4.01 PU after 6 weeks of steroid treatment and we stopped the steroid for 6 weeks, the blood flow became 29.86 +/- 2.59 PU. The merit of our experiment established a model of study in avascular necrosis of the femoral head in rabbits. Copyright 1994 S. Karger AG, Basel

Collision Based Blood Cell Distribution of the Blood Flow

Science.gov (United States)

Cinar, Yildirim

2003-11-01

Introduction: The goal of the study is the determination of the energy transferring process between colliding masses and the application of the results to the distribution of the cell, velocity and kinetic energy in arterial blood flow. Methods: Mathematical methods and models were used to explain the collision between two moving systems, and the distribution of linear momentum, rectilinear velocity, and kinetic energy in a collision. Results: According to decrease of mass of the second system, the velocity and momentum of constant mass of the first system are decreased, and linearly decreasing mass of the second system captures a larger amount of the kinetic energy and the rectilinear velocity of the collision system on a logarithmic scale. Discussion: The cause of concentration of blood cells at the center of blood flow an artery is not explained by Bernoulli principle alone but the kinetic energy and velocity distribution due to collision between the big mass of the arterial wall and the small mass of blood cells must be considered as well.

Studies on so-called redistribution phenomenon of cerebral blood flow imaging

International Nuclear Information System (INIS)

Oba, Hiroshi

1989-01-01

To elucidate the relationship between so-called redistribution phenomenon and metabolism or viability of the brain tissue, a new quantitative triple-radionuclide autoradiography was developed, whereby making it possible to compare both late images and reditribution of IMP with cerebral metabolism in experimentally induced unilateral ischemic brain tissue of rats. Iodine-123 IMP and I-125 IMP were used as tracers for early and late imaging, and H-3 amino acid mixture or H-3 H-2 deoxyglucose as a tracer for protein synthesis or glucose metabolism imaging. There was no significant relationship between redistribution index and protein synthesis or glucose metabolism. Protein synthesis was remarkably decreased in the affected hemisphere regardless of redistribution index values. Although the redistribution indices showed a gentle peak at approximately 34 μ mol/100 g/ min of glucose metabolism, there was no obvious relationship between either late images or redistribution index images and glucose metabolism images. Redistribution indices showed a maximum value at approximately 40 to 50 ml/100 g/min of cerebral blood flow. Reverse redistribution was observed with 160 ml/100 g/min or more of flow. Thin layer chromatographic findings were similar in the affected and non-affected resions, suggesting redistribution of a lipophilic IMP metabolite of p-iodoamphetamine in the affected region. In vitro autoradiography revealed no significant reduction in binding ability of IMP to the affected ischemic cortex. In a computer simulation study for brain activity curve, brain activity at 150 min was found to be almost constant at more than 25 ml/100 g/min of flow. IMP redistribution was unlikely to reflect directly either brain metabolism or function, and both blood flow partition coefficient and blood flow values were independently responsible for cerebral kinetics of IMP. (N.K.)

Changes in blood flow during one stage lengthening of bone: an experimental study in rats.

Science.gov (United States)

Kwon, S T; Chung, C Y

2000-06-01

Distraction osteogenesis is a well-accepted method of bone lengthening. Its disadvantages, however, are that it requires an external fixator and takes a long time. One-stage lengthening therefore offers certain advantages. A first point of reference for the safe limits of this procedure might be the changes of blood flow, and this is also the crucial factor in deciding on the appropriate method of lengthening, particularly where the hand or foot is involved. Using a laser Doppler flowmeter we measured blood flow in the dorsum of the foot after using bilateral minimonofixators to lengthen the tibias of 15 Sprague-Dawley rats. They were lengthened in four stages: stage 0 (before lengthening); stage I--12.5%; stage II--25%; and stage III--31.25% of lengthening. The blood flow during stage I decreased to 79% compared to that of stage 0; 16% during stage II; and 1% during stage III. This study suggests that the maximal permissible extent of lengthening might be less than a quarter according to the blood flow as suggested by this animal model.

Glial and neuronal control of brain blood flow

DEFF Research Database (Denmark)

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

2010-01-01

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

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

DEFF Research Database (Denmark)

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

2008-01-01

a significant association between IV and SC administration of synthetic GLP-2 and changes in mesenteric blood flow. An exponential dose-response relationship was observed after IV infusion. The meal-induced changes in mesenteric blood flow over time were similar to those obtained by SC GLP-2. Thus, our results......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...

Regional cerebral blood flow characteristics of the Sturge-Weber syndrome

International Nuclear Information System (INIS)

Riela, A.R.; Stump, D.A.; Roach, E.S.; McLean, W.T. Jr.; Garcia, J.C.

1985-01-01

Four patients with the Sturge-Weber syndrome were studied using the non-invasive Xenon-133 inhalation technique. All four patients had decreased regional cerebral blood flow in the area of their lesion, and in two patients who were subsequently tested with 5% carbon dioxide inhalation, impaired vasomotor reactivity was documented. Diminished regional cerebral blood flow is consistent with previously described nuclide flow studies which demonstrated a delay in the initial perfusion blush in the region of the abnormal vasculature. The focal decrease in blood flow was greatest in the most severely affected patient, but was also prominent in the two younger patients, both of whom have excellent neurologic function. These studies suggest that localized decrease in blood flow and vasomotor dysfunction in Sturge-Weber syndrome can precede the occurrence of severe neurologic impairment and extensive cerebral atrophy and possibly be a major contributing factor in progressive dysfunction. A secondary observation was that the blood flow in the unaffected hemisphere was significantly greater in two children compared to the two adults and was similar to the age-related differences reported for normal children and adults

Blood flow autoregulation in pedicled flaps

DEFF Research Database (Denmark)

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

2009-01-01

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......, the flow in the pedicle was reduced and the flow was recorded. RESULTS: The flaps showed a strong autoregulatory response with complete compensation for flow reductions of up to 70-80%. Infusion of nimodipine caused a 28+/-10% increase in blood flow and removed the autoregulation. Papaverine caused...... a further increase in blood flow by 61+/-19%. The time control experiments proved that the experimental procedure was reproducible and stable over time. CONCLUSIONS: A tissue flap can nearly completely compensate for repeated flow reductions of up to 70-80%. This is due to a decrease in the peripheral...

Blood flow patterns underlie developmental heart defects.

Science.gov (United States)

Midgett, Madeline; Thornburg, Kent; Rugonyi, Sandra

2017-03-01

Although cardiac malformations at birth are typically associated with genetic anomalies, blood flow dynamics also play a crucial role in heart formation. However, the relationship between blood flow patterns in the early embryo and later cardiovascular malformation has not been determined. We used the chicken embryo model to quantify the extent to which anomalous blood flow patterns predict cardiac defects that resemble those in humans and found that restricting either the inflow to the heart or the outflow led to reproducible abnormalities with a dose-response type relationship between blood flow stimuli and the expression of cardiac phenotypes. Constricting the outflow tract by 10-35% led predominantly to ventricular septal defects, whereas constricting by 35-60% most often led to double outlet right ventricle. Ligation of the vitelline vein caused mostly pharyngeal arch artery malformations. We show that both cardiac inflow reduction and graded outflow constriction strongly influence the development of specific and persistent abnormal cardiac structure and function. Moreover, the hemodynamic-associated cardiac defects recapitulate those caused by genetic disorders. Thus our data demonstrate the importance of investigating embryonic blood flow conditions to understand the root causes of congenital heart disease as a prerequisite to future prevention and treatment. NEW & NOTEWORTHY Congenital heart defects result from genetic anomalies, teratogen exposure, and altered blood flow during embryonic development. We show here a novel "dose-response" type relationship between the level of blood flow alteration and manifestation of specific cardiac phenotypes. We speculate that abnormal blood flow may frequently underlie congenital heart defects. Copyright © 2017 the American Physiological Society.

Study of the portal blood flow by gamma-scintigraphy in rectal administration of 133Xe solution

International Nuclear Information System (INIS)

Vorontsov, Yu.P.; Dmitrievnkov, B.N.; Andronov, S.V.; Alferov, G.A.

1981-01-01

Data on 133 Xe running through the liver during the administration of its solutions rectally (intraintestinally) and directly into the system of the portal vein (into one of the mesenteric veins) have been correlated in experiment on 12 rabbits. Good correlation of the mean of 133 Xe (passing has been shown for both methods of the portal blood flow study). A possibility to study the hepatic blood flow on the basis of clinical results using rectal administration of 133 Xe solution is discussed. The authors discuss the mechanism of 133 Xe penetration from the solution into the blood through the rectal wall

Uteroplacental blood flow during alkalosis in the sheep

International Nuclear Information System (INIS)

Buss, D.D.; Bisgard, G.E.; Rawlings, C.A.; Rankin, J.H.G.

1975-01-01

Uteroplacental blood flow was measured by the radioactive-microsphere technique in eight near-term pregnant ewes during a normal control period and during maternal metabolic alkalosis. All measurements were made on awake, unanesthetized animals. Alkalosis, defined for this study as an arterial pH of 7.60 or greater, was produced by the oral administration of sodium bicarbonate, 3 g/kg body wt. The rise in pH thus produced was unaccompanied by significant changes in systemic arterial blood pressure and cardiac output, while maternal arterial P/sub CO 2 / rose slightly from control levels. Cotyledonary blood flow declined from a control value of 1.177 ml/min to 1.025 ml/min during alkalosis. This decline of 13 percent in cotyledonary blood flow is significant (P less than 0.02). Blood flow to the remaining uterine tissue, or noncotyledonary uterus, did not change with alkalosis, being maintained at approximately 195 ml/min. It is concluded that maternal alkalosis, unaccompanied by major changes in P /sub CO 2 / and systemic arterial pressure, causes a small increase in the resistance of the uteroplacental circulation

Regulation of bone blood flow in humans

DEFF Research Database (Denmark)

Heinonen, Ilkka; Boushel, Robert; Hellsten, Ylva

2018-01-01

of cyclooxygenase (COX) enzyme, thus prostaglandin (PG) synthesis on femoral bone marrow blood flow by positron emission tomography in healthy young men at rest and during one leg dynamic exercise. In an additional group of healthy men, the role of adenosine (ADO) in the regulation of BBF during exercise......The mechanisms that regulate bone blood flow (BBF) in humans are largely unknown. Animal studies suggest that nitric oxide (NO) could be involved and in the present study we investigated the effects of inhibition of nitric oxide synthase (NOS) alone and in combination with inhibition.......036), but did not affect BBF significantly during exercise (5.5±1.4 ml/100g/min, p=0.25). On the other hand, while combined NOS and COX inhibition did not cause any further reduction of blood flow at rest (0.6±0.2 ml/100g/min), the combined blockade reduced BBF during exercise by ~21%, to 5.0±1.8 ml/100g/min (p...

Three-dimensional imaging of absolute blood flow velocity and blood vessel position under low blood flow velocity based on Doppler signal information included in scattered light from red blood cells

Science.gov (United States)

Kyoden, Tomoaki; Akiguchi, Shunsuke; Tajiri, Tomoki; Andoh, Tsugunobu; Hachiga, Tadashi

2017-11-01

The development of a system for in vivo visualization of occluded distal blood vessels for diabetic patients is the main target of our research. We herein describe two-beam multipoint laser Doppler velocimetry (MLDV), which measures the instantaneous multipoint flow velocity and can be used to observe the blood flow velocity in peripheral blood vessels. By including a motorized stage to shift the measurement points horizontally and in the depth direction while measuring the velocity, the path of the blood vessel in the skin could be observed using blood flow velocity in three-dimensional space. The relationship of the signal power density between the blood vessel and the surrounding tissues was shown and helped us identify the position of the blood vessel. Two-beam MLDV can be used to simultaneously determine the absolute blood flow velocity distribution and identify the blood vessel position in skin.

Intraneural blood flow analysis during an intraoperative Phalen's test in carpal tunnel syndrome.

Science.gov (United States)

Yayama, Takafumi; Kobayashi, Shigeru; Awara, Kousuke; Takeno, Kenichi; Miyazaki, Tsuyoshi; Kubota, Masafumi; Negoro, Kohei; Baba, Hisatoshi

2010-08-01

Phalen's test has been one of the most significant of clinical signs when making a clinical diagnosis of idiopathic carpal tunnel syndrome (CTS). However, it is unknown whether intraneural blood flow changes during Phalen's test in patients with CTS. In this study, an intraoperative Phalen's test was conducted in patients with CTS to observe the changes in intraneural blood flow using a laser Doppler flow meter. During Phalen's test, intraneural blood flow showed a sharp decrease, which lasted for 1 min. Intraneural blood flow decreased by 56.7%-100% (average, 78.0%) in the median nerve relative to the blood flow before the test. At 1 min after completing the test, intraneural blood flow returned to the baseline value. After carpal tunnel release, there was no marked decrease in intraneural blood flow. This study demonstrated that the blood flow in the median nerve is reduced when Phalen's test is performed in vivo. Copyright 2010 Orthopaedic Research Society. Published by Wiley Periodicals, Inc.

Ocular blood flow decreases during passive heat stress in resting humans.

Science.gov (United States)

Ikemura, Tsukasa; Miyaji, Akane; Kashima, Hideaki; Yamaguchi, Yuji; Hayashi, Naoyuki

2013-12-06

Heat stress induces various physiological changes and so could influence ocular circulation. This study examined the effect of heat stress on ocular blood flow. Ocular blood flow, end-tidal carbon dioxide (P(ET)CO2) and blood pressure were measured for 12 healthy subjects wearing water-perfused tube-lined suits under two conditions of water circulation: (1) at 35 °C (normothermia) for 30 min and (2) at 50 °C for 90 min (passive heat stress). The blood-flow velocities in the superior temporal retinal arteriole (STRA), superior nasal retinal arteriole (SNRA), and the retinal and choroidal vessels (RCV) were measured using laser-speckle flowgraphy. Blood flow in the STRA and SNRA was calculated from the integral of a cross-sectional map of blood velocity. PETCO2 was clamped at the normothermia level by adding 5% CO2 to the inspired gas. Passive heat stress had no effect on the subjects' blood pressures. The blood-flow velocity in the RCV was significantly lower after 30, 60 and 90 min of passive heat stress than the normothermic level, with a peak decrease of 18 ± 3% (mean ± SE) at 90 min. Blood flow in the STRA and SNRA decreased significantly after 90 min of passive heat stress conditions, with peak decreases of 14 ± 3% and 14 ± 4%, respectively. The findings of this study suggest that passive heat stress decreases ocular blood flow irrespective of the blood pressure or arterial partial pressure of CO2.

Cerebral blood flow changes in response to elevated intracranial pressure in rabbits and bluefish: a comparative study.

Science.gov (United States)

Beiner, J M; Olgivy, C S; DuBois, A B

1997-03-01

In mammals, the cerebrovascular response to increases in intracranial pressure may take the form of the Cushing response, which includes increased mean systemic arterial pressure, bradycardia and diminished respirations. The mechanism, effect and value of these responses are debated. Using laser-Doppler flowmetry to measure cerebral blood flow, we analyzed the cardiovascular responses to intracranial pressure raised by epidural infusion of mock cerebrospinal fluid in the bluefish and in the rabbit, and compare the results. A decline in cerebral blood flow preceding a rise in mean systemic arterial pressure was observed in both species. Unlike bluefish, rabbits exhibit a threshold of intracranial pressure below which cerebral blood flow was maintained and no cardiovascular changes were observed. The difference in response between the two species was due to the presence of an active autoregulatory system in the cerebral tissue of rabbits and its absence in bluefish. For both species studied, the stimulus for the Cushing response seems to be a decrement in cerebral blood flow. The resulting increase in the mean systemic arterial pressure restores cerebral blood flow to levels approaching controls.

Renal blood flow regulation and arterial pressure fluctuations: a case study in nonlinear dynamics

DEFF Research Database (Denmark)

Holstein-Rathlou, N H; Marsh, D J

1994-01-01

in which the kidney is obliged to operate. Were it not for renal blood flow autoregulation, it would be difficult to regulate renal excretory processes so as to maintain whole body variables within narrow bounds. Autoregulation is the noise filter on which other renal processes depend for maintaining...... a relatively noise-free environment in which to work. Because of the time-varying nature of the blood pressure, we have concentrated in this review on the now substantial body of work on the dynamics of renal blood flow regulation and the underlying mechanisms. Renal vascular control mechanisms are not simply....... The significance of deterministic chaos in the context of renal blood flow regulation is that the system regulating blood flow undergoes a physical change to a different dynamical state, and because the change is deterministic, there is every expectation that the critical change will yield itself to experimental...

A numerical study of blood flow using mixture theory

OpenAIRE

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

2014-01-01

In this paper, we consider the two dimensional flow of blood in a rectangular microfluidic channel. We use Mixture Theory to treat this problem as a two-component system: One component is the red blood cells (RBCs) modeled as a generalized Reiner–Rivlin type fluid, which considers the effects of volume fraction (hematocrit) and influence of shear rate upon viscosity. The other component, plasma, is assumed to behave as a linear viscous fluid. A CFD solver based on OpenFOAM® was developed and ...

Complex blood flow patterns in an idealized left ventricle: A numerical study

Science.gov (United States)

Tagliabue, Anna; Dedè, Luca; Quarteroni, Alfio

2017-09-01

In this paper, we study the blood flow dynamics in a three-dimensional (3D) idealized left ventricle of the human heart whose deformation is driven by muscle contraction and relaxation in coordination with the action of the mitral and aortic valves. We propose a simplified but realistic mathematical treatment of the valves function based on mixed time-varying boundary conditions (BCs) for the Navier-Stokes equations modeling the flow. These switchings in time BCs, from natural to essential and vice versa, model either the open or the closed configurations of the valves. At the numerical level, these BCs are enforced by means of the extended Nitsche's method (Tagliabue et al., Int. J. Numer. Methods Fluids, 2017). Numerical results for the 3D idealized left ventricle obtained by means of Isogeometric Analysis are presented, discussed in terms of both instantaneous and phase-averaged quantities of interest and validated against those available in the literature, both experimental and computational. The complex blood flow patterns are analysed to describe the characteristic fluid properties, to show the transitional nature of the flow, and to highlight its main features inside the left ventricle. The sensitivity of the intraventricular flow patterns to the mitral valve properties is also investigated.

Blood flow determinations utilizing digital densitometry

International Nuclear Information System (INIS)

Lois, F.; Mankovich, N.J.; Gomes, A.S.

1987-01-01

A method of obtaining relative and absolute blood flow measurements from digital densitometry was evaluated with a simulated vessel phantom and a hydrodynamic model. A digital vascular imaging system capable of acquisition in 512 2 and 1024 2 mode was used. Relative and absolute blood flow were measured using parameters derived from the densitometric curve. Since application of densitometric data to absolute flow measurements requires the vessel diameter, an algorithm for vessel size determination was created. Gray scale changes were demonstrated to be linearly related to contrast concentration. The variance of vessel size determination was significantly different in all combinations of 1024 2 and 512 2 imaging with 15 cm or 35 cm field size. The error in vessel size determination was significantly less using the larger 1024 2 matrix and the smaller 15 cm image intensifier field size, as shown by the smaller variance. In relative flow determinations, there was good correlation between the flow and four parameters of the densitometric curve with no significant differences between 512 2 and 1024 2 imaging. Absolute flow determinations had slightly lower correlation to actual flow but were not significantly different from relative flow determinations. Relative and absolute blood flow determinations can be performed adequately with either 512 2 or 1024 2 imaging. The increased accuracy in vessel size determination with 1024 2 imaging makes this high resolution system potentially perferable to determine absolute blood flow. (orig.)

A study of the acute effect of smoking on cerebral blood flow using {sup 99m}Tc-ECD SPET

Energy Technology Data Exchange (ETDEWEB)

Yamamoto, Yuka; Nishiyama, Yoshihiro; Monden, Toshihide; Satoh, Katashi; Ohkawa, Motoomi [Department of Radiology, Faculty of Medicine, Kagawa Medical University, 1750-1 Ikenobe, Miki-cho, Kita-gun, Kagawa, 761-0793 (Japan)

2003-04-01

Cigarette smoking is known to be associated with atherosclerosis, is an important risk factor for stroke and has other serious effects. The aim of this study was to evaluate the acute effect of cigarette smoking on cerebral blood flow using statistical parametric mapping (SPM). Ten healthy volunteers with a smoking habit were studied using technetium-99m-labelled ethylcysteinate dimer single-photon emission tomography (SPET). We evaluated the regional cerebral blood flow under the smoking and resting states. The regional cerebral blood flow on smoking-activated SPET was significantly decreased in the whole brain as compared with that on resting SPET. Our findings therefore suggest that one of the acute effects of cigarette smoking is to induce a diffuse decrease in cerebral blood flow. (orig.)

Local viscosity distribution in bifurcating microfluidic blood flows

Science.gov (United States)

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

2018-03-01

The red blood cell (RBC) aggregation phenomenon is majorly responsible for the non-Newtonian nature of blood, influencing the blood flow characteristics in the microvasculature. Of considerable interest is the behaviour of the fluid at the bifurcating regions. In vitro experiments, using microchannels, have shown that RBC aggregation, at certain flow conditions, affects the bluntness and skewness of the velocity profile, the local RBC concentration, and the cell-depleted layer at the channel walls. In addition, the developed RBC aggregates appear unevenly distributed in the outlets of these channels depending on their spatial distribution in the feeding branch, and on the flow conditions in the outlet branches. In the present work, constitutive equations of blood viscosity, from earlier work of the authors, are applied to flows in a T-type bifurcating microchannel to examine the local viscosity characteristics. Viscosity maps are derived for various flow distributions in the outlet branches of the channel, and the location of maximum viscosity magnitude is obtained. The viscosity does not appear significantly elevated in the branches of lower flow rate as would be expected on the basis of the low shear therein, and the maximum magnitude appears in the vicinity of the junction, and towards the side of the outlet branch with the higher flow rate. The study demonstrates that in the branches of lower flow rate, the local viscosity is also low, helping us to explain why the effects of physiological red blood cell aggregation have no adverse effects in terms of in vivo vascular resistance.

Thermographic venous blood flow characterization with external cooling stimulation

Science.gov (United States)

Saxena, Ashish; Ng, E. Y. K.; Raman, Vignesh

2018-05-01

Experimental characterization of blood flow in a human forearm is done with the application of continuous external cooling based active thermography method. Qualitative and quantitative detection of the blood vessel in a thermal image is done, along with the evaluation of blood vessel diameter, blood flow direction, and velocity in the target blood vessel. Subtraction based image manipulation is performed to enhance the feature contrast of the thermal image acquired after the removal of external cooling. To demonstrate the effect of occlusion diseases (obstruction), an external cuff based occlusion is applied after the removal of cooling and its effect on the skin rewarming is studied. Using external cooling, a transit time method based blood flow velocity estimation is done. From the results obtained, it is evident that an external cooling based active thermography method can be used to develop a diagnosis tool for superficial blood vessel diseases.

Feasibility study of red blood cell debulking by magnetic field-flow fractionation with step-programmed flow.

Science.gov (United States)

Moore, Lee R; Williams, P Stephen; Nehl, Franziska; Abe, Koji; Chalmers, Jeffrey J; Zborowski, Maciej

2014-02-01

Emerging applications of rare cell separation and analysis, such as separation of mature red blood cells from hematopoietic cell cultures, require efficient methods of red blood cell (RBC) debulking. We have tested the feasibility of magnetic RBC separation as an alternative to centrifugal separation using an approach based on the mechanism of magnetic field-flow fractionation (MgFFF). A specially designed permanent magnet assembly generated a quadrupole field having a maximum field of 1.68 T at the magnet pole tips, zero field at the aperture axis, and a nearly constant radial field gradient of 1.75 T/mm (with a negligible angular component) inside a cylindrical aperture of 1.9 mm (diameter) and 76 mm (length). The cell samples included high-spin hemoglobin RBCs obtained by chemical conversion of hemoglobin to methemoglobin (met RBC) or by exposure to anoxic conditions (deoxy RBC), low-spin hemoglobin obtained by exposure of RBC suspension to ambient air (oxy RBC), and mixtures of deoxy RBC and cells from a KG-1a white blood cell (WBC) line. The observation that met RBCs did not elute from the channel at the lower flow rate of 0.05 mL/min applied for 15 min but quickly eluted at the subsequent higher flow rate of 2.0 mL/min was in agreement with FFF theory. The well-defined experimental conditions (precise field and flow characteristics) and a well-established FFF theory verified by studies with model cell systems provided us with a strong basis for making predictions about potential practical applications of the magnetic RBC separation.

Real-time direct measurement of spinal cord blood flow at the site of compression: relationship between blood flow recovery and motor deficiency in spinal cord injury.

Science.gov (United States)

Hamamoto, Yuichiro; Ogata, Tadanori; Morino, Tadao; Hino, Masayuki; Yamamoto, Haruyasu

2007-08-15

An in vivo study to measure rat spinal cord blood flow in real-time at the site of compression using a newly developed device. To evaluate the change in thoracic spinal cord blood flow by compression force and to clarify the association between blood flow recovery and motor deficiency after a spinal cord compression injury. Until now, no real-time measurement of spinal cord blood flow at the site of compression has been conducted. In addition, it has not been clearly determined whether blood flow recovery is related to motor function after a spinal cord injury. Our blood flow measurement system was a combination of a noncontact type laser Doppler system and a spinal cord compression device. The rat thoracic spinal cord was exposed at the 11th vertebra and spinal cord blood flow at the site of compression was continuously measured before, during, and after the compression. The functioning of the animal's hind-limbs was evaluated by the Basso, Beattie and Bresnahan scoring scale and the frequency of voluntary standing. Histologic changes such as permeability of blood-spinal cord barrier, microglia proliferation, and apoptotic cell death were examined in compressed spinal cord tissue. The spinal blood flow decreased on each increase in the compression force. After applying a 5-g weight, the blood flow decreased to compression), while no significant difference was observed between the 20-minute ischemia group and the sham group. In the 20-minute ischemia group, the rats whose spinal cord blood flow recovery was incomplete showed significant motor function loss compared with rats that completely recovered blood flow. Extensive breakdown of blood-spinal cord barrier integrity and the following microglia proliferation and apoptotic cell death were detected in the 40-minute complete ischemia group. Duration of ischemia/compression and blood flow recovery of the spinal cord are important factors in the recovery of motor function after a spinal cord injury.

Low cerebral blood flow in hypotensive perinatal distress

International Nuclear Information System (INIS)

Lou, H.C.; Lassen, N.A.; Friis-Hansen, B.

1977-01-01

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

Esophageal blood flow in the cat. Normal distribution and effects of acid perfusion

International Nuclear Information System (INIS)

Hollwarth, M.E.; Smith, M.; Kvietys, P.R.; Granger, D.N.

1986-01-01

The radioactive microsphere technique was used to estimate blood flow to different regions of the esophagus and to adjacent regions of the stomach before and after perfusion of the esophagus with hydrochloric acid (pH 1.5) for 5 min. Under resting conditions total blood flow, as well as blood flow to the mucosal-submucosal layer and the muscular layer, to both sphincters was significantly higher than to the esophageal body. Blood flow to the adjacent regions of the stomach was significantly higher than esophageal blood flow. Acid perfusion resulted in a large increase in total blood flow in both sphincters and the lower esophageal body. Gastric blood flow was not altered by acid perfusion. The esophageal hyperemia resulted primarily from an increase in blood flow to the muscular layer; mucosal-submucosal blood flow was increased only in the lower esophageal sphincter. The present study indicates that short periods (5 min) of gastroesophageal reflux may increase esophageal blood flow

Longitudinal optical monitoring of blood flow in breast tumors during neoadjuvant chemotherapy

Science.gov (United States)

Cochran, J. M.; Chung, S. H.; Leproux, A.; Baker, W. B.; Busch, D. R.; DeMichele, A. M.; Tchou, J.; Tromberg, B. J.; Yodh, A. G.

2017-06-01

We measure tissue blood flow markers in breast tumors during neoadjuvant chemotherapy and investigate their correlation to pathologic complete response in a pilot longitudinal patient study (n  =  4). Tumor blood flow is quantified optically by diffuse correlation spectroscopy (DCS), and tissue optical properties, blood oxygen saturation, and total hemoglobin concentration are derived from concurrent diffuse optical spectroscopic imaging (DOSI). The study represents the first longitudinal DCS measurement of neoadjuvant chemotherapy in humans over the entire course of treatment; it therefore offers a first correlation between DCS flow indices and pathologic complete response. The use of absolute optical properties measured by DOSI facilitates significant improvement of DCS blood flow calculation, which typically assumes optical properties based on literature values. Additionally, the combination of the DCS blood flow index and the tissue oxygen saturation from DOSI permits investigation of tissue oxygen metabolism. Pilot results from four patients suggest that lower blood flow in the lesion-bearing breast is correlated with pathologic complete response. Both absolute lesion blood flow and lesion flow relative to the contralateral breast exhibit potential for characterization of pathological response. This initial demonstration of the combined optical approach for chemotherapy monitoring provides incentive for more comprehensive studies in the future and can help power those investigations.

Measurement of blood flow through surgical anastomosis using the radioactive microsphere technique

Energy Technology Data Exchange (ETDEWEB)

Hummel, S.J.; Delgado, G.; Butterfield, A.; Dritschilo, A.; Harbert, J.

1985-10-01

Two different radioactive microspheres ( U Ce and UWSc) were used to measure blood flow to an area of the large intestine in dogs before and after a surgical resection was performed with surgical staples. The healing of an anastomosis is theoretically related to the blood flow to the anastomotic site. Blood flow studies were conducted in three dogs using this technique. The average blood flow preoperatively was 0.558 mL/minute per gram and 1.04 mL/minute per gram postoperatively. These results indicate a statistically significant increase in blood flow at the anastomotic site six days after anastomosis when compared with the blood flow to the same area before any surgical procedures.

Measurement of blood flow through surgical anastomosis using the radioactive microsphere technique

International Nuclear Information System (INIS)

Hummel, S.J.; Delgado, G.; Butterfield, A.; Dritschilo, A.; Harbert, J.

1985-01-01

Two different radioactive microspheres ( 141 Ce and 46 Sc) were used to measure blood flow to an area of the large intestine in dogs before and after a surgical resection was performed with surgical staples. The healing of an anastomosis is theoretically related to the blood flow to the anastomotic site. Blood flow studies were conducted in three dogs using this technique. The average blood flow preoperatively was 0.558 mL/minute per gram and 1.04 mL/minute per gram postoperatively. These results indicate a statistically significant increase in blood flow at the anastomotic site six days after anastomosis when compared with the blood flow to the same area before any surgical procedures

Role of hypotension in decreasing cerebral blood flow in porcine endotoxemia

International Nuclear Information System (INIS)

Miller, C.F.; Breslow, M.J.; Shapiro, R.M.; Traystman, R.J.

1987-01-01

The role of reduced arterial blood pressure (MAP) in decreasing cerebral blood flow (CBF) during endotoxemia was studied in pentobarbital-anesthetized pigs. Microspheres were used to measure regional CBF changes during MAP manipulations in animals with and without endotoxin. Endotoxin decreased MAP to 50 mmHg and decreased blood flow to the cortex and cerebellum without affecting cerebral cortical oxygen consumption (CMRo 2 ). Elevating MAP from 50 to 70 mmHg during endotoxemia with norepinephrine did not change cortical blood flow or CMRo 2 but increased cerebellar blood flow. Brain stem blood flow was not affected by endotoxin or norepinephrine. When MAP was decreased to 50 mmHg by hemorrhage without endotoxin, no change in blood flow to cortex, cerebellum, or brain stem was observed from base-line levels. These results suggest that decreased MAP below a lower limit for cerebral autoregulation does not account for the decreased CBF observed after endotoxin

Data adaptive estimation of transversal blood flow velocities

DEFF Research Database (Denmark)

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

2014-01-01

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.......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...

Cerebral blood flow measured by positron emission tomography during normothermic cardiopulmonary bypass: An experimental porcine study

DEFF Research Database (Denmark)

Thomassen, Sisse Anette; Kjaergaard, Benedict; Alstrup, Aage Kristian Olsen

2018-01-01

emission tomography (PET) using 15O-labelled water with no pharmacological interventions to maintain the MAP. Methods: Eight pigs (69-71 kg) were connected to normothermic CPB. After 60 minutes (min) with a CPB pump flow of 60 mL/kg/min, the pigs were changed to either 35 mL/kg/min or 47.5 mL/kg/min for 60......Background: Mean arterial blood pressure (MAP) and/or pump flow during normothermic cardiopulmonary bypass (CPB) are the most important factors of cerebral perfusion. The aim of this study was to explore the influence of CPB blood flow on cerebral blood flow (CBF) measured by dynamic positron...... min and, thereafter, all the pigs returned to 60 mL/kg/min for another 60 min. The MAP was measured continuously and the CBF was measured by positron emission tomography (PET) during spontaneous circulation and at each CPB pump flow after 30 min of steady state. Results: Two pigs were excluded due...

SPECT myocardial blood flow quantitation toward clinical use: a comparative study with {sup 13}N-Ammonia PET myocardial blood flow quantitation

Energy Technology Data Exchange (ETDEWEB)

Hsu, Bailing [University of Missouri-Columbia, Nuclear Science and Engineering Institute, Columbia, Missouri (United States); Hu, Lien-Hsin; Yang, Bang-Hung; Ting, Chien-Hsin; Huang, Wen-Sheng [Taipei Veterans General Hospital, Department of Nuclear Medicine, Taipei (China); Chen, Lung-Ching [Shin Kong Wu-Ho Su Memorial Hospital, Division of Cardiology, Taipei (China); Chen, Yen-Kung [Shin Kong Wu-Ho Su Memorial Hospital, Department of Nuclear Medicine, Taipei (China); Hung, Guang-Uei [Chang Bing Show Chwan Memorial Hospital, Department of Nuclear Medicine, Changhua (China); Wu, Tao-Cheng [National Yang-Ming University, Cardiovascular Research Center, Taipei (China)

2017-01-15

The aim of this study was to evaluate the accuracy of myocardial blood flow (MBF) quantitation of {sup 99m}Tc-Sestamibi (MIBI) single photon emission computed tomography (SPECT) compared with {sup 13}N-Ammonia (NH3) position emission tomography (PET) on the same cohorts. Recent advances of SPECT technologies have been applied to develop MBF quantitation as a promising tool to diagnose coronary artery disease (CAD) for areas where PET MBF quantitation is not available. However, whether the SPECT approach can achieve the same level of accuracy as the PET approach for clinical use still needs further investigations. Twelve healthy volunteers (HVT) and 16 clinical patients with CAD received both MIBI SPECT and NH3 PET flow scans. Dynamic SPECT images acquired with high temporary resolution were fully corrected for physical factors and processed to quantify K1 using the standard compartmental modeling. Human MIBI tracer extraction fraction (EF) was determined by comparing MIBI K1 and NH3 flow on the HVT group and then used to convert flow values from K1 for all subjects. MIBI and NH3 flow values were systematically compared to validate the SPECT approach. The human MIBI EF was determined as [1.0-0.816*exp(-0.267/MBF)]. Global and regional MBF and myocardial flow reserve (MFR) of MIBI SPECT and NH3 PET were highly correlated for all subjects (global R{sup 2}: MBF = 0.92, MFR = 0.78; regional R{sup 2}: MBF ≥ 0.88, MFR ≥ 0.71). No significant differences for rest flow, stress flow, and MFR between these two approaches were observed (All p ≥ 0.088). Bland-Altman plots overall revealed small bias between MIBI SPECT and NH3 PET (global: ΔMBF = -0.03Lml/min/g, ΔMFR = 0.07; regional: ΔMBF = -0.07 - 0.06, ΔMFR = -0.02 - 0.22). Quantitation with SPECT technologies can be accurate to measure myocardial blood flow as PET quantitation while comprehensive imaging factors of SPECT to derive the variability between these two approaches were fully addressed and corrected

SPECT myocardial blood flow quantitation toward clinical use: a comparative study with "1"3N-Ammonia PET myocardial blood flow quantitation

International Nuclear Information System (INIS)

Hsu, Bailing; Hu, Lien-Hsin; Yang, Bang-Hung; Ting, Chien-Hsin; Huang, Wen-Sheng; Chen, Lung-Ching; Chen, Yen-Kung; Hung, Guang-Uei; Wu, Tao-Cheng

2017-01-01

The aim of this study was to evaluate the accuracy of myocardial blood flow (MBF) quantitation of "9"9"mTc-Sestamibi (MIBI) single photon emission computed tomography (SPECT) compared with "1"3N-Ammonia (NH3) position emission tomography (PET) on the same cohorts. Recent advances of SPECT technologies have been applied to develop MBF quantitation as a promising tool to diagnose coronary artery disease (CAD) for areas where PET MBF quantitation is not available. However, whether the SPECT approach can achieve the same level of accuracy as the PET approach for clinical use still needs further investigations. Twelve healthy volunteers (HVT) and 16 clinical patients with CAD received both MIBI SPECT and NH3 PET flow scans. Dynamic SPECT images acquired with high temporary resolution were fully corrected for physical factors and processed to quantify K1 using the standard compartmental modeling. Human MIBI tracer extraction fraction (EF) was determined by comparing MIBI K1 and NH3 flow on the HVT group and then used to convert flow values from K1 for all subjects. MIBI and NH3 flow values were systematically compared to validate the SPECT approach. The human MIBI EF was determined as [1.0-0.816*exp(-0.267/MBF)]. Global and regional MBF and myocardial flow reserve (MFR) of MIBI SPECT and NH3 PET were highly correlated for all subjects (global R"2: MBF = 0.92, MFR = 0.78; regional R"2: MBF ≥ 0.88, MFR ≥ 0.71). No significant differences for rest flow, stress flow, and MFR between these two approaches were observed (All p ≥ 0.088). Bland-Altman plots overall revealed small bias between MIBI SPECT and NH3 PET (global: ΔMBF = -0.03Lml/min/g, ΔMFR = 0.07; regional: ΔMBF = -0.07 - 0.06, ΔMFR = -0.02 - 0.22). Quantitation with SPECT technologies can be accurate to measure myocardial blood flow as PET quantitation while comprehensive imaging factors of SPECT to derive the variability between these two approaches were fully addressed and corrected. (orig.)

Cerebral blood flow studied by 133Xe inhalation technique in parkinsonism: loss of hyperfrontal pattern

International Nuclear Information System (INIS)

Bes, A.; Gueell, A.; Fabre, N.; Dupui, P.; Victor, G.; Geraud, G.

1983-01-01

Cerebral blood flow (grey matter flow) in parkinsonism requires further investigation. The noninvasive method of 133 Xe inhalation permits study of larger numbers of subjects than previously used invasive techniques such as the intracarotid 133 Xe injection method. Measurements were made in this laboratory in 30 subjects having Parkinson's disease. Mean hemispheric blood flow (F1) values were 70.4 +/- 9.3 ml/100 g/min, compared to 76.3 for a group of age-matched normal subjects, which is a decrease of -7.8%. The most striking difference was the loss of the hyperfrontal distribution in parkinsonism. The prefrontal F1 values were only 1.8% greater than the hemisphere grey matter flow, compared with 8.5% in controls of a similar age group

Effect of intra-aortic balloon pump on coronary blood flow during different balloon cycles support: A computer study.

Science.gov (United States)

Aye, Thin Pa Pa; Htet, Zwe Lin; Singhavilai, Thamvarit; Naiyanetr, Phornphop

2015-01-01

Intra-aortic balloon pump (IABP) has been used in clinical treatment as a mechanical circulatory support device for patients with heart failure. A computer model is used to study the effect on coronary blood flow (CBF) with different balloon cycles under both normal and pathological conditions. The model of cardiovascular and IABP is developed by using MATLAB SIMULINK. The effect on coronary blood flow has been studied under both normal and pathological conditions using different balloon cycles (balloon off; 1:4; 1:2; 1:1). A pathological heart is implemented by reducing the left ventricular contractility. The result of this study shows that the rate of balloon cycles is related to the level of coronary blood flow.

Brain blood flow and blood pressure during hypoxia in the epaulette shark Hemiscyllium ocellatum, a hypoxia-tolerant elasmobranch.

Science.gov (United States)

Söderström, V; Renshaw, G M; Nilsson, G E

1999-04-01

The key to surviving hypoxia is to protect the brain from energy depletion. The epaulette shark (Hemiscyllium ocellatum) is an elasmobranch able to resist energy depletion and to survive hypoxia. Using epi-illumination microscopy in vivo to observe cerebral blood flow velocity on the brain surface, we show that cerebral blood flow in the epaulette shark is unaffected by 2 h of severe hypoxia (0.35 mg O2 l-1 in the respiratory water, 24 C). Thus, the epaulette shark differs from other hypoxia- and anoxia-tolerant species studied: there is no adenosine-mediated increase in cerebral blood flow such as that occurring in freshwater turtles and cyprinid fish. However, blood pressure showed a 50 % decrease in the epaulette shark during hypoxia, indicating that a compensatory cerebral vasodilatation occurs to maintain cerebral blood flow. We observed an increase in cerebral blood flow velocity when superfusing the normoxic brain with adenosine (making sharks the oldest vertebrate group in which this mechanism has been found). The adenosine-induced increase in cerebral blood flow velocity was reduced by the adenosine receptor antagonist aminophylline. Aminophylline had no effect upon the maintenance of cerebral blood flow during hypoxia, however, indicating that adenosine is not involved in maintaining cerebral blood flow in the epaulette shark during hypoxic hypotension.

The blood flow changes associated with idiopathic and secondary intracranial hypertension

International Nuclear Information System (INIS)

Bateman, G.

2002-01-01

Full text: The radiological diagnosis of idiopathic intracranial hypertension (IIH) is one of exclusion and as the MR venogram is prone to flow artefacts, the diagnosis of secondary intracranial hypertension (SIH) can also be problematic. The purpose of this paper is to define the blood flow characteristics, which are useful in the diagnosis of these conditions. Twelve patients with clinical findings suggestive of IIH and 12 control subjects were investigated with MR venography and MR flow quantification studies of the cerebral arteries and veins. Total cerebral blood flow, superior sagittal sinus (SSS) and straight sinus (ST) blood flows were measured. MR venography confirmed 7 of the 12 patients had venous outflow obstruction and thus SIH. The remaining 5 patients had IIH. The control patients mean total blood flow was 855 ml/min, the SSS flow was 400ml/min and the ST flow 117 ml/min. The total blood flow in the IIH patients was 46% higher (P = 0.0002) and the ST blood flow 38% higher (P = 0.05) than the control group, the SSS flow was 17% higher but this failed to reach significance. In SIH the SSS flow was reduced by 25% (P = 0.003) compared with the control group, the total and ST blood flow were not significantly altered. In IIH there is hyperaemia and the SSS appears limited in its ability to increase flow, therefore venous collaterals carry a greater load. In SIH, selective obstruction of the SSS reduces flow in this vessel but total blood flow is normal indicating there is also increased flow in collateral veins. Presumably the limited ability of the SSS to drain blood away from the brain in each condition raises venous sinus pressure and alters CSF resorption giving raised CSF pressure. Copyright (2002) Blackwell Science Pty Ltd

Positron emission tomography detects greater blood flow and less blood flow heterogeneity in the exercising skeletal muscles of old compared with young men during fatiguing contractions

Science.gov (United States)

Rudroff, Thorsten; Weissman, Jessica A; Bucci, Marco; Seppänen, Marko; Kaskinoro, Kimmo; Heinonen, Ilkka; Kalliokoski, Kari K

2014-01-01

The purpose of this study was to investigate blood flow and its heterogeneity within and among the knee muscles in five young (26 ± 6 years) and five old (77 ± 6 years) healthy men with similar levels of physical activity while they performed two types of submaximal fatiguing isometric contraction that required either force or position control. Positron emission tomography (PET) and [15O]-H2O were used to determine blood flow at 2 min (beginning) and 12 min (end) after the start of the tasks. Young and old men had similar maximal forces and endurance times for the fatiguing tasks. Although muscle volumes were lower in the older subjects, total muscle blood flow was similar in both groups (young men: 25.8 ± 12.6 ml min−1; old men: 25.1 ± 15.4 ml min−1; age main effect, P = 0.77) as blood flow per unit mass of muscle in the exercising knee extensors was greater in the older (12.5 ± 6.2 ml min−1 (100 g)−1) than the younger (8.6 ± 3.6 ml min−1 (100 g)−1) men (age main effect, P = 0.001). Further, blood flow heterogeneity in the exercising knee extensors was significantly lower in the older (56 ± 27%) than the younger (67 ± 34%) men. Together, these data show that although skeletal muscles are smaller in older subjects, based on the intact neural drive to the muscle and the greater, less heterogeneous blood flow per gram of muscle, old fit muscle achieves adequate exercise hyperaemia. Key points The results of previous studies that attempted to demonstrate the effects of ageing on skeletal muscle blood flow are controversial because these studies used indirect assessments of skeletal muscle blood flow obtained via whole limb blood flow measurements that provide no information on the distribution of blood flow within particular muscles. We used positron emission tomography to measure blood flow per gram of muscle in old and young men with similar levels of physical activity

Effective RES blood flow changes in children with homozygous β-thalassemia in relation to blood transfusion

International Nuclear Information System (INIS)

Karpathios, T.; Dimitriou, P.; Giamouris, J.; Nicolaidou, P.; Antipas, S.E.; Matsaniotis, N.

1983-01-01

Denatured radioiodinated human serum albumin (DHA) clearance studies at a dose of 1 mg/kg body wt., were carried out in 16 thalassemic children, prior to and 7-10 days following blood transfusion, to investigate changes of the effective RES blood flow which might accompany the posttransfusion spleen size diminution. A statistically significant increase (P<0.001) of the DHA plasma clearance rate was observed 7-10 days following blood transfusion denoting an increase of the blood flow to the effective RES while at the same time the spleen diminished in size. It is suggested that changes in the effective RES blood flow in these patients are directly related to changes in the intrasplenic circulatory capacity. (orig.)

Dynamics of blood flow: twenty years of achievement

International Nuclear Information System (INIS)

Rosendorff, C.

1988-01-01

The physiology of blood circulation has evolved from the descriptive phenomenology of William Harvey's time to an interdisciplinary science, involving elements of fluid dynamics, vessel wall mechanics, electrophysiology, cell biology, biochemistry and molecular biology. Most of these new developments have occured during the lifetime of the South African Medical Research Council. Highlights of the research undertaken by the Council regarding circulatory physiology are given. In the 1960s the use of xenon-133 to study the flow of blood to the brain resulted in the first systematic description of cerebral blood flow and its control by sympathetic nerves. During the 1970s this technique was refined and the use of radioactive microspheres for the measurement of tissue blood flow was developed. Research concerning the control of blood vessels in the kidney was also carried out, and this showed that the sympathetic nerves control renal blood flow by releasing a local hormone called renin. The renal release of renin was later recognised as being important in the control of blood pressure. Another development was the discovery that vascular sensitivity to noradrenaline was increased in certain types of liver diseases. An analysis of the blood of patients with obstructive jaundice showed that the substance responsible for this noradrenaline effect was a combination of cholesterol and lipo-protein. This led to the theory that excessive cholesterol in the blood may be dangerous. In the late 1970s a shift in research emphasis to coronary artery physiology occurred and the 1980s saw research move into the area of cell biology

Tumor blood flow and pH changes after glucose administration

International Nuclear Information System (INIS)

Thistlethwaite, A.J.; Tupchong, L.; Leeper, D.B.

1987-01-01

The authors used a laser doppler technique to correlate blood flow changes with pH changes in human tumors after glucose ingestion. Three PTs with large superficial tumors ingested 100 gm glucose. A 21g needle pH electrode (Micro-electrodes, Inc.) and a 21g ''Laserflo'' fiberoptic laser doppler blood flow probe (TSI, Minneapolis, MN) were used at the same location. Blood glucose was measured by finger stick every 7.5 min. One PT with a squamous cell CA with extensive necrosis had only a small increase in blood glucose and an increase in tumor pH. Blood flow readings were within 6.4-18.4ml/100g/min. Another PT with a squamous CA had a drop in tumor pH (7.46 to 7.05) as blood glucose increased from 85 to 137 mg/dl by 55 min. Blood flow remained in a range of 7.7-13.8 ml/100g/min with a mean of 11.4. The third PT with a sarcoma had tumor pH and blood glucose measurements on two occasions, with similar results. Blood glucose rose from approx. 100 to 150 mg/dl by 52.5 min with a drop in tumor pH from approx. 7.4 to 7.25. On the second trial, tumor blood flow was measured and, while erratic (6.4-24.9ml/100g/min), decreased by approx. 50%. These preliminary data show that the laser doppler blood flow technique is quite sensitive to movement artifact and interference by free hemoglobin. Currently, it is inconclusive whether blood flow is altered with blood glucose and tumor pH changes. Further studies may prove this to be a valuable tool in predicting tumor response to hyperthermia

Measurement of bone blood flow in sheep

International Nuclear Information System (INIS)

Rosenthal, M.S.; Lehner, C.E.; Pearson, D.W.; Kanikula, T.; Adler, G.; Venci, R.; Lanphier, E.H.; DeLuca, P.M. Jr.

1984-01-01

Bone blood flow in sheep tibia has been estimated via the measurement of the perfusion limited clearance of 41 Ar from the bone mineral matrix following fast neutron activation of 44 Ca. Tibia blood flows were estimated for the intact sheep, and after the installation of an intramedullary pressure tap to elevate bone marrow pressure by saline infusion. The results indicate that normal blood flow in the tibia is in the range of 1.1 to 3.7 ml/100ml-min in the intact animal and at normal marrow pressure. With an elevated intramedullary pressure of approximately 100 mmHg, the bone blood flow measured varied around 0.5 to 1.1 ml/100ml-min. 12 refs., 5 figs., 1 tab

Non-gated fetal MRI of umbilical blood flow in an acardiac twin

Energy Technology Data Exchange (ETDEWEB)

Hata, Nobuhiko [University of Tokyo, Graduate School of Information Science and Technology, Tokyo (Japan); Brigham and Women' s Hospital, Department of Radiology, Boston, MA (United States); Wada, Toru [University of Tokyo, Graduate School of Information Science and Technology, Tokyo (Japan); Kashima, Kyoko; Okada, Yoshiyuki [National Center for Child Health and Development, Department of Radiology, Tokyo (Japan); Unno, Nobuya [Nagano Children' s Hospital, Center for Perinatal Medicine, Nagano (Japan); Kitagawa, Michihiro [National Center for Child Health and Development, Department of Prenatal Medicine and Maternal Care, Tokyo (Japan); Chiba, Toshio [National Center for Child Health and Development, Department of Strategic Medicine, Tokyo (Japan)

2005-08-01

Currently, the standard method of diagnosis of twin reversed arterial perfusion (TRAP) sequence is ultrasound imaging. The use of MRI for flow visualization may be a useful adjunct to US imaging for assessing the presence of retrograde blood flow in the acardiac fetus and/or umbilical artery. The technical challenge in fetal MRI flow imaging, however, is that fetal electrocardiogram (ECG) monitoring required for flow imaging is currently unavailable in the MRI scanner. A non-gated MRI flow imaging technique that requires no ECG monitoring was developed using the t-test to detect blood flow in 20 slices of phase-contrast MRI images randomly scanned at the same location over multiple cardiac cycles. A feasibility study was performed in a 24-week acardiac twin that showed no umbilical flow sonographically. Non-gated MRI flow images clearly indicated the presence of blood flow in the umbilical artery to the acardiac twin; however, there was no blood flow beyond the abdomen. This study leads us to conjecture that non-gated MRI flow imaging is sensitive in detecting low-range blood flow velocity and can be an adjunct to Doppler US imaging. (orig.)

Non-gated fetal MRI of umbilical blood flow in an acardiac twin

International Nuclear Information System (INIS)

Hata, Nobuhiko; Wada, Toru; Kashima, Kyoko; Okada, Yoshiyuki; Unno, Nobuya; Kitagawa, Michihiro; Chiba, Toshio

2005-01-01

Currently, the standard method of diagnosis of twin reversed arterial perfusion (TRAP) sequence is ultrasound imaging. The use of MRI for flow visualization may be a useful adjunct to US imaging for assessing the presence of retrograde blood flow in the acardiac fetus and/or umbilical artery. The technical challenge in fetal MRI flow imaging, however, is that fetal electrocardiogram (ECG) monitoring required for flow imaging is currently unavailable in the MRI scanner. A non-gated MRI flow imaging technique that requires no ECG monitoring was developed using the t-test to detect blood flow in 20 slices of phase-contrast MRI images randomly scanned at the same location over multiple cardiac cycles. A feasibility study was performed in a 24-week acardiac twin that showed no umbilical flow sonographically. Non-gated MRI flow images clearly indicated the presence of blood flow in the umbilical artery to the acardiac twin; however, there was no blood flow beyond the abdomen. This study leads us to conjecture that non-gated MRI flow imaging is sensitive in detecting low-range blood flow velocity and can be an adjunct to Doppler US imaging. (orig.)

Modeling microcirculatory blood flow: current state and future perspectives.

Science.gov (United States)

Gompper, Gerhard; Fedosov, Dmitry A

2016-01-01

Microvascular blood flow determines a number of important physiological processes of an organism in health and disease. Therefore, a detailed understanding of microvascular blood flow would significantly advance biophysical and biomedical research and its applications. Current developments in modeling of microcirculatory blood flow already allow to go beyond available experimental measurements and have a large potential to elucidate blood flow behavior in normal and diseased microvascular networks. There exist detailed models of blood flow on a single cell level as well as simplified models of the flow through microcirculatory networks, which are reviewed and discussed here. The combination of these models provides promising prospects for better understanding of blood flow behavior and transport properties locally as well as globally within large microvascular networks. © 2015 Wiley Periodicals, Inc.

Comparative studies of D2 receptors and cerebral blood flow in hemi-parkinsonism rats

International Nuclear Information System (INIS)

Lin, Y.; Lin, X.

2000-01-01

To study the relationship between dopamine (DA) D 2 receptors and cerebral blood flow in hemiparkinsonism rats. Hemi-parkinsonism rats were made by stereotaxic 6-hydroxy dopamine (6-OH-DA) lesions in substantia nigra and ventral tegmental area, apomorphine (Apo) which could induce the successful model rat rotates toward the intact side was used to screen that rats, 125 I-IBZM in vivo autoradiography and 99m Tc-HM-PAO regional brain biodistribution were used to study D 2 receptors and cerebral blood flow. The HPLC-ECD were used to measure the concentration of DA and it metabolites homovanillic acid (HVA), 3,4-dehydroxyphenyl acetic acid (DOPAC) in bilateral striatum (ST). The lesioned side ST DA and its metabolites HVA DOPAC reduced significantly than that of the intact side and pseudo-operated control group, ST/cerebellum (CB) 125 I-IBZM uptake ratio was 8.04 ±0.71 in lesioned side of hemi-parkinsonism rats, significantly increased compared with the intact side and the pseudo-operated group (p 99m Tc 30.1±4.53% enhancement as compared to the intact side, and also show good correlation with 30 min Apo induced rotation numbers (r=0.98), the regional cerebral blood flow study didn't show significant difference between bilateral brain cortex area (p>0.05). The DA content decreased significantly and induced an up-regulation of ST D 2 receptor binding sites in 6-OH-DA lesioned side in hemi-parkinsonism rats, the increased percentage of lesioned-intact side ST/CB 125 I-IBZM uptake ratio showed good correlation with rotation behavior induced by Apo. Compare with cerebral blood flow, D 2 receptor reflected by IBZM seems to be more specific and earlier to detect the cerebral functional impairment in experimental hemi-parkinsonism

Numerical Modeling of Interstitial Fluid Flow Coupled with Blood Flow through a Remodeled Solid Tumor Microvascular Network.

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Soltani, M; Chen, P

2013-01-01

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.

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.

Relationship among visual field, blood flow, and neural structure measurements in glaucoma.

Science.gov (United States)

Hwang, John C; Konduru, Ranjith; Zhang, Xinbo; Tan, Ou; Francis, Brian A; Varma, Rohit; Sehi, Mitra; Greenfield, David S; Sadda, Srinivas R; Huang, David

2012-05-17

To determine the relationship among visual field, neural structural, and blood flow measurements in glaucoma. Case-control study. Forty-seven eyes of 42 patients with perimetric glaucoma were age-matched with 27 normal eyes of 27 patients. All patients underwent Doppler Fourier-domain optical coherence tomography to measure retinal blood flow and standard glaucoma evaluation with visual field testing and quantitative structural imaging. Linear regression analysis was performed to analyze the relationship among visual field, blood flow, and structure, after all variables were converted to logarithmic decibel scale. Retinal blood flow was reduced in glaucoma eyes compared to normal eyes (P flow and structural loss of rim area and retinal nerve fiber layer (RNFL). There was no correlation or paradoxical correlation between blood flow and structure. Multivariate regression analysis revealed that reduced blood flow and structural loss are independent predictors of visual field loss. Each dB decrease in blood flow was associated with at least 1.62 dB loss in mean deviation (P ≤ 0.001), whereas each dB decrease in rim area and RNFL was associated with 1.15 dB and 2.56 dB loss in mean deviation, respectively (P ≤ 0.03). There is a close link between reduced retinal blood flow and visual field loss in glaucoma that is largely independent of structural loss. Further studies are needed to elucidate the causes of the vascular dysfunction and potential avenues for therapeutic intervention. Blood flow measurement may be useful as an independent assessment of glaucoma severity.

A study of renal blood flow regulation using the discrete wavelet transform

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Pavlov, Alexey N.; Pavlova, Olga N.; Mosekilde, Erik; Sosnovtseva, Olga V.

2010-02-01

In this paper we provide a way to distinguish features of renal blood flow autoregulation mechanisms in normotensive and hypertensive rats based on the discrete wavelet transform. Using the variability of the wavelet coefficients we show distinctions that occur between the normal and pathological states. A reduction of this variability in hypertension is observed on the microscopic level of the blood flow in efferent arteriole of single nephrons. This reduction is probably associated with higher flexibility of healthy cardiovascular system.

Quantitative myocardial blood flow with Rubidium-82 PET

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

2015-01-01

Positron emission tomography (PET) allows assessment of myocardial blood flow in absolute terms (ml/min/g). Quantification of myocardial blood flow (MBF) and myocardial flow reserve (MFR) extend the scope of conventional semi-quantitative myocardial perfusion imaging (MPI): e.g. in 1) identificat......Positron emission tomography (PET) allows assessment of myocardial blood flow in absolute terms (ml/min/g). Quantification of myocardial blood flow (MBF) and myocardial flow reserve (MFR) extend the scope of conventional semi-quantitative myocardial perfusion imaging (MPI): e.g. in 1...... 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...

Regulation of Blood Flow in Contracting Skeletal Muscle in Aging

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Piil, Peter Bergmann

Oxygen delivery to skeletal muscle is regulated precisely to match the oxygen demand; however, with aging the regulation of oxygen delivery during exercise is impaired. The present thesis investigated mechanisms underlying the age-related impairment in regulation of blood flow and oxygen delivery......GMP) was used as intervention, and skeletal muscle blood flow, oxygen delivery, and functional sympatholysis was examined. The two studies included 53 healthy, habitually active, male subjects. All subjects participated in an experimental day in which femoral arterial blood flow and blood pressure were assessed...... that improving sympatholytic capacity by training may be a slower process in older than in young men. In conclusion, this thesis provides new important knowledge related to the regulation of skeletal muscle blood flow in aging. Specifically, it demonstrates that changes in cGMP signaling is an underlying cause...

Radionuclide and dopplergraphic assessment of portal hepatic blood flow in opisthorchiasis

International Nuclear Information System (INIS)

Borodulin, V.G.; Ermolitskij, N.M.; Zavadovskaya, V.D.; Prosekina, N.M.; Borodulin, Yu.V.

1996-01-01

Dynamic studies of the portal blood flow were carried out in 88 patients using colloid radionuclide gold-198 and Tc-99m-phytate and in 84 patients by dopplerography. Radionuclide studies showed that both radiopharmaceutical adequately reflected the portal blood flow in the liver. Portal blood flow values obtained by the duplex echographic method were 0.7 times lower than these estimated by radionuclide indirect angiography. The authors come to a conclusions that the share of the liver in colloid capture should be taken into consideration for the correct estimation of the level of portal hepatic hemodynamics. Portal hepatic blood flow was found markedly reduced in patients with chronic opisthorchiasis in comparison with normal controls, this difference being more expressed in male patients [ru

Testicular blood flow in varicocele

International Nuclear Information System (INIS)

Iwamoto, Teruaki; Hirokawa, Makoto.

1986-01-01

Radioisotopic scrotal angiography was applied for study of testicular blood flow of patients with varicocele. Following iv. bolus injection of 10 ∼ 20 mCi of Tc human serum albumine, Tc RBC or Tc pertechnetate, time activity curve of radioactivity at corresponding bilateral areas of scrotum was simultaneously generated and compared. Eighty-four patients with overt varicocele (grade 2 and 3) at left side only, were selected for the present study and eight healthy young volunteers were studied as a control group. Three patterns of time activity curves were recognized. They are as follows. Type 1, where radioactivity was accumulated quickly in left side and then decreased gradually. Bilateral time activity curves were asymmetrical. Type 2, where time activity curves rose gradually and to a higher level at the left side than at the right side. Type 3, where bilateral time activity curves increased gradually, and symmetrically. All of the control group showed the same pattern as Type 3. Of the 84 patients examined, 34 patients showed Type 1, including 7 with grade 2 and 27 with grade 3. Twenty-four patients showed Type 2. consisting of 12 with grade 2 and 12 with grade 3. Twenty-six patients showed Type 3, consisting of 14 with grade 2 and 12 with grade 3. We presumed the following about testicular blood flow in varicocele: Type 1 pattern shows retrograde blood flow from the renal vein to the internal spermatic vein, Type 2 pattern shows poor venous return through the internal spermatic vein and Type 3 pattern shows good venous return though the presence of dilatated pampiniform plexus. (author)

Neonatal changes in renal blood flow distribution in puppies

International Nuclear Information System (INIS)

Aschinberg, L.C.; Goldsmith, D.I.; Olbing, H.; Spitzer, A.; Edelmann, C.M. Jr.; Blaufox, M.D.

1975-01-01

The intrarenal distribution of blood flow was studied in 31 newborn mongrel puppies from 18 h to 70 days using xenon washout and krypton autoradiography. Mean renal blood flow increased from 0.39 +- 0.05 ml/g per min (SE) the 1st wk to 2.06 +- 0.12 ml/g per min at 6 wk. During the 1st wk of life the renal cortex was perfused homogeneously at 0.88 +- 0.19 ml/g min (SE) and accounted for 35 +- 4 percent of the renal blood flow. During the 2nd wk a narrow, rapidly perfused zone of outer cortex was identified which was perfused at 3.35 +- 0.26 ml/g per min, received 19.53 +- 5.05 percent of the total renal blood flow, and represented 15 +- 4 percent of the mass of the total cortex. The inner cortex and outer medulla at this time received 53.40 +- 4.12 percent of the flow at 1.07 +- 0.08 ml/g per min. Outer cortical flow increased with age reaching adult values by about 6 to 10 wk when the rapidly perfused area represented 40 +- 8 percent of the cortex. These changes are parallel to the results of previously reported studies with microspheres in newborn puppies and are compatible with the well-established maturational changes noted in neonates of several species. They represent the first gas-washout studies in animals during the first 6 wk of life

Studies of blood flow in human nasal mucosa with /sup133/Xe washout technique and laser doppler flowmetry

International Nuclear Information System (INIS)

Olsson, P.

1986-01-01

The techniques were applied for studies of the influence of environmental temperature on the human nasal mucosa, for studies of mediators in nasal allergy and for studies of the sympathetic neurogenic control of blood flow in the nasal mucosa. The results show that the two techniques are complementary to one another. The /sup133/Xe washout technique is useful for semiquantitative estimations of blood flow in the deeper parts of the mucosa, while the laser doppler technique is especially suited for continuous recordings of relative blood flow changes in the superficial part of the mucosa. Vascular changes may take part in body temperature regulation changes may take part in body temperature regulation as well as in conditioning of respiratory air. The results support the theories that changes in nasal mucosal blood flow are related to body temperature control, while conditioning of inspiratory air may be more dependent on mucosal blood content. The observed dissociation between changes in the resistance and the capacitance vessels also illustrates that these vascular segments are regulated in different ways. The present results indicate that leukotriene D/sub4/ might contribute to an increased blood flow in the nasal mucosa and to blockage of the nasal airway in the acute allergic reaction. Vasomotion is demonstrated to be present in the nasal mucosa, and it appears to be partly dependent on sympathetic neurogenic activity. The development of the present techniques, means that vascular changes involved in normal nasal function and in nasal disease may be evaluated by a new approach. (author)

Influence of Dai-kenchu-to (DKT) on human portal blood flow.

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Ogasawara, Takashi; Morine, Yuji; Ikemoto, Tetsuya; Imura, Satoru; Fujii, Masahiko; Soejima, Yuji; Shimada, Mitsuo

2008-01-01

Dai-kenchu-to (DKT) is known as an herbal medicine used for postoperative ileus. However, no report exists about the effect of DKT on portal blood flow. The aim of this study is to clarify the influence of DKT on portal blood flow. To healthy volunteers (Healthy; n = 6), cirrhotic patients (Cirrhosis; n = 7) and liver-transplant patients (LTx; n = 3), DKT (2.5g) with 100mL of warm water was orally administrated in the DKT group, and only warm water was administrated in the control group. The portal blood flow rate (M-VEL: cm/sec.) and portal blood flow (Flow volume: mL/min.) was measured each time after administration using an ultrasonic Doppler method. Furthermore, the arterial blood pressure and heart rate was measured at the same time points. In the DKT group, a significant increase of M-VEL (120%) and flow volume (150%) 30 minutes after administration was observed in both Healthy and Cirrhosis in comparison with the control group. In LTx, there was also a significant increase of flow volume (128%) 30 minutes after administration. However, there was no change in average blood pressure and heart rate in all groups. DKT increases portal blood flow in early phase after oral administration without any significant changes in the blood pressure and heart rate.

Increased bone marrow blood flow in polycythemia vera

International Nuclear Information System (INIS)

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

1983-01-01

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

Increased bone marrow blood flow in polycythemia vera

Energy Technology Data Exchange (ETDEWEB)

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

1983-01-01

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

Comparative study of methods for blood flow measurement within transverse sinuses by using MR

International Nuclear Information System (INIS)

Gao Gejun; Feng Xiaoyuan; Yang Bojie; Geng Daoying

2003-01-01

Objective: To assess the accuracy of two-dimensional phase contrast (2D-PC) MR method for blood flow measurement within transverse sinuses by comparing this method with cine phase contrast (cine-PC) MR and Doppler in volunteers and patients. Methods: (1) A total of 12 transverse sinuses were examined in 8 healthy volunteers. 2D-PC MR and cine-PC MR were used respectively to measure the transverse area of flow, the flow velocities, and the volumetric flow rates in the same position in every transverse sinus. Paired t-test was used for comparison between the results determined by 2D-PC MR and that determined by cine-PC MR. (2) A total of 6 transverse sinuses were examined in 5 patients who needed operation. 2D-PC MR was used to determine the blood flow velocity of transverse sinus before operation, and Doppler was used to determine the blood flow velocity of the same transverse sinus during operation. The linear regression analysis was used for statistical analysis. Results: (1) Statistical analysis indicated that there were no significant difference among the transverse area of flow (t = -1.106, P = 0.293), the flow velocities (t = 0.262, P = 0.798), and the volumetric flow rates (t = 0.439, P = 0.669) measured by using 2D-PC MR and cine PC MR, respectively. (2) The correlation between flow velocities determined by 2D-PC MR imaging before operation and that determined by Doppler during operation was in excellent agreement (Y-circumflex = 1.303 x + 0.62, r 2 = 0.88). Conclusion: 2D-PC MR may be a practical convenient method for blood flow measurement within transverse sinuses system

Ocular blood flow decreases during passive heat stress in resting humans

OpenAIRE

Ikemura, Tsukasa; Miyaji, Akane; Kashima, Hideaki; Yamaguchi, Yuji; Hayashi, Naoyuki

2013-01-01

Background Heat stress induces various physiological changes and so could influence ocular circulation. This study examined the effect of heat stress on ocular blood flow. Findings Ocular blood flow, end-tidal carbon dioxide (P ETCO2) and blood pressure were measured for 12 healthy subjects wearing water-perfused tube-lined suits under two conditions of water circulation: (1) at 35°C (normothermia) for 30 min and (2) at 50°C for 90 min (passive heat stress). The blood-flow velocities in the s...

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)

2001-04-01

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.)

Cerebellar blood flow in methylmercury poisoning (Minamata disease)

International Nuclear Information System (INIS)

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

2001-01-01

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.)

Blood in the gastric lumen increases splanchnic blood flow and portal pressure in portal-hypertensive rats.

Science.gov (United States)

Chen, L; Groszmann, R J

1996-10-01

In portal-hypertensive humans, portal blood flow and pressure increase after a meal. These hemodynamic changes may increase variceal rupture risk. The aim of this study was to determine whether blood in the stomach lumen increases splanchnic flow and portal pressure (PP) in portal-hypertensive rats. superior mesenteric artery flow and PP were measured in conscious, unrestrained, fasted partial portal vein-ligated rats with chronically implanted Doppler flow probes or portal vein catheters before and after gavage with heparinized, warmed blood from donor rats, air, standard meal, or empty tube. Percentage of changes in flow and pressure from baseline were significantly greater after gavage with blood (an increase of 22.6% +/- 3.5% and an increase of 16.4% +/- 3.1%, respectively) than empty tube (an increase of 3.4% +/- 0.6% and a decrease of 5.4% +/- 3.5%, respectively) (P empty tube (P calories probably contributes to these hemodynamic changes. In patients with variceal hemorrhage, blood in the stomach may increase the risk of persistent variceal bleeding or rebleeding.

Ocular Blood Flow and Normal Tension Glaucoma

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Ning Fan

2015-01-01

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

Glial and neuronal control of brain blood flow

DEFF Research Database (Denmark)

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

2010-01-01

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

Partitioning of red blood cell aggregates in bifurcating microscale flows

Science.gov (United States)

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

2017-03-01

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.

Blood flow patterns during incremental and steady-state aerobic exercise.

Science.gov (United States)

Coovert, Daniel; Evans, LeVisa D; Jarrett, Steven; Lima, Carla; Lima, Natalia; Gurovich, Alvaro N

2017-05-30

Endothelial shear stress (ESS) is a physiological stimulus for vascular homeostasis, highly dependent on blood flow patterns. Exercise-induced ESS might be beneficial on vascular health. However, it is unclear what type of ESS aerobic exercise (AX) produces. The aims of this study are to characterize exercise-induced blood flow patterns during incremental and steady-state AX. We expect blood flow pattern during exercise will be intensity-dependent and bidirectional. Six college-aged students (2 males and 4 females) were recruited to perform 2 exercise tests on cycleergometer. First, an 8-12-min incremental test (Test 1) where oxygen uptake (VO2), heart rate (HR), blood pressure (BP), and blood lactate (La) were measured at rest and after each 2-min step. Then, at least 48-hr. after the first test, a 3-step steady state exercise test (Test 2) was performed measuring VO2, HR, BP, and La. The three steps were performed at the following exercise intensities according to La: 0-2 mmol/L, 2-4 mmol/L, and 4-6 mmol/L. During both tests, blood flow patterns were determined by high-definition ultrasound and Doppler on the brachial artery. These measurements allowed to determine blood flow velocities and directions during exercise. On Test 1 VO2, HR, BP, La, and antegrade blood flow velocity significantly increased in an intensity-dependent manner (repeated measures ANOVA, pflow velocity did not significantly change during Test 1. On Test 2 all the previous variables significantly increased in an intensity-dependent manner (repeated measures ANOVA, pflow patterns during incremental and steady-state exercises include both antegrade and retrograde blood flows.

Cerebral blood flow in temporal lobe epilepsy: a partial volume correction study

International Nuclear Information System (INIS)

Giovacchini, Giampiero; Bonwetsch, Robert; Theodore, William H.; Herscovitch, Peter; Carson, Richard E.

2007-01-01

Previous studies in temporal lobe epilepsy (TLE) have shown that, owing to brain atrophy, positron emission tomography (PET) can overestimate deficits in measures of cerebral function such as glucose metabolism (CMR glu ) and neuroreceptor binding. The magnitude of this effect on cerebral blood flow (CBF) is unexplored. The aim of this study was to assess CBF deficits in TLE before and after magnetic resonance imaging-based partial volume correction (PVC). Absolute values of CBF for 21 TLE patients and nine controls were computed before and after PVC. In TLE patients, quantitative CMR glu measurements also were obtained. Before PVC, regional values of CBF were significantly (p glu in middle and inferior temporal cortex, fusiform gyrus and hippocampus both before and after PVC. A significant positive relationship between disease duration and AIs for CMR glu , but not CBF, was detected in hippocampus and amygdala, before but not after PVC. PVC should be used for PET CBF measurements in patients with TLE. Reduced blood flow, in contrast to glucose metabolism, is mainly due to structural changes. (orig.)

Coronary blood flow during cardiopulmonary resuscitation in swine

International Nuclear Information System (INIS)

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

1984-01-01

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

Influence of Gravity on Blood Volume and Flow Distribution

Science.gov (United States)

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

1999-01-01

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

Oscillations and Multiple Equilibria in Microvascular Blood Flow.

Science.gov (United States)

Karst, Nathaniel J; Storey, Brian D; Geddes, John B

2015-07-01

We investigate the existence of oscillatory dynamics and multiple steady-state flow rates in a network with a simple topology and in vivo microvascular blood flow constitutive laws. Unlike many previous analytic studies, we employ the most biologically relevant models of the physical properties of whole blood. Through a combination of analytic and numeric techniques, we predict in a series of two-parameter bifurcation diagrams a range of dynamical behaviors, including multiple equilibria flow configurations, simple oscillations in volumetric flow rate, and multiple coexistent limit cycles at physically realizable parameters. We show that complexity in network topology is not necessary for complex behaviors to arise and that nonlinear rheology, in particular the plasma skimming effect, is sufficient to support oscillatory dynamics similar to those observed in vivo.

Blood flow and blood volume in the femoral heads of healthy adults according to age. Measurement with positron emission tomography (PET)

International Nuclear Information System (INIS)

Kubo, Toshikazu; Kimori, Kokuto; Nakamura, Fuminori; Inoue, Shigehiro; Fujioka, Mikihiro; Ueshima, Keiichiro; Hirasawa, Yasusuke; Ushijima, Yo; Nishimura, Tsunehiko

2001-01-01

To deepen understanding of hemodynamics in the femoral head, i.e., the essential factor in clarifying pathogenesis of hip disorders, this study examined blood flow and blood volume in the femoral heads of healthy adults, and their changes with age, by using positron emission tomography (PET). In 16 healthy adult males (age: 20-78 years old, mean age: 42 years), blood flow was measured by means of the H 2 15 O dynamic study method, and blood volume was measured by means of the 15 O-labeled carbon monoxide bolus inhalation method. Blood flow was 1.68-6.47 ml/min/100 g (mean ±SD: 3.52±1.2), and blood volume was 1.67-6.03 ml/100 g (mean ±SD: 3.00±1.27). Blood flow significantly decreased (p<0.01) with age, and blood volume significantly increased (P<0.05). PET was useful in the measurement of blood flow and blood volume in the femoral heads. With age, physiological hemodynamic changes also increased in femoral heads. (author)

Regional cerebral blood flow in the patient with brain tumor

International Nuclear Information System (INIS)

Tsuchida, Shohei

1993-01-01

Regional cerebral blood flow (rCBF) was measured with xenon-enhanced CT (Xe-CT) in 21 cases of intracranial tumors (13 meningiomas, 5 gliomas, 3 metastatic brain tumors). Peritumoral edema was graded as mild, moderate or severe based on the extent of edema on CT and MRI. According to intratumoral blood flow distribution patterns, three patterns were classified as central type with relatively high blood flow at the center of the tumor, homogeneous type with an almost homogeneous blood flow distribution, and marginal type with relatively high blood flow at the periphery of the tumor. High grade astrocytoma and metastatic brain tumor showed marginal type blood flow and moderate or severe edema except in one case. Five meningiomas with severe peritumoral edema revealed marginal type blood flow and four with mild peritumoral edema showed central type blood flow, except for one case. No correlation was found between the extent of peritumoral edema and histological subtype, tumor size, location, duration of clinical history, vascularization on angiogram, and mean blood flow in the tumor. These results suggest that blood flow distribution patterns within the tumor may affect the extension of peritumoral edema. Pre- and postoperative rCBFs were evaluated with Xe-CT and IMP-SPECT in 7 cases, mean rCBF of peritumoral edema was 6.2 ml/100 g/min preoperatively, and discrepancy between rCBF on Xe-CT and that on IMP-SPECT was shown in the remote cortical region ipsilateral to the tumor. Postoperative rCBF revealed an improved blood flow in both adjacent and remote areas, suggesting that the decreased blood flow associated with brain tumors might be relieved after surgery. (author) 53 refs

Post-exercise blood flow restriction attenuates hyperemia similarly in males and females.

Science.gov (United States)

Dankel, Scott J; Mouser, J Grant; Jessee, Matthew B; Mattocks, Kevin T; Buckner, Samuel L; Loenneke, Jeremy P

2017-08-01

Our laboratory recently demonstrated that post-exercise blood flow restriction attenuated muscle hypertrophy only in females, which we hypothesized may be due to alterations in post-exercise blood flow. The aim of this study is to test our previous hypothesis that sex differences in blood flow would exist when employing the same protocol. Twenty-two untrained individuals (12 females; 10 males) performed two exercise sessions, each involving one set of elbow flexion exercise to volitional failure on the right arm. The experimental condition had blood flow restriction applied for a 3 min post-exercise period, whereas the control condition did not. Blood flow was measured using an ultrasound at the brachial artery and was taken 1 and 4 min post-exercise. This corresponded to 1 min post inflation and 1 min post deflation in the experimental condition. There were no differences in the alterations in blood flow between the control and experimental conditions when examined across sex. Increases in blood flow [mean (standard deviation)] were as follows: males 1 min [control 764 (577) %; experimental 113 (108) %], males 4 min [control 346 (313) %; experimental 449 (371) %], females 1 min [control 558 (367) %; experimental 87 (105) %], and females 4 min [control 191 (183) %; experimental 328 (223) %]. It does not appear that the sex-specific attenuation of muscle hypertrophy we observed previously can be attributed to different alterations in post-exercise blood flow. Future studies may wish to replicate our previous training study, or examine alternative mechanisms which may be sex specific.

Renal transplantant blood flow in patients with acute tubular necrosis

Energy Technology Data Exchange (ETDEWEB)

Huic, D; Crnkovic, S; Bubic-Filipi, L J; Grosev, D; Dodig, P; Porapat, M; Puretic, Z [Univ. Hospital Rebro, Zagreb (Croatia)

1997-09-01

The aim of this study was to investigate the quantity of renal transport blood flow in patients affected by acute tubular necrosis (ATN). During the four years period two hundred and thirty-three studies were performed using {sup 99m}Tc pertechnetate and {sup 131}I - OIH. Renal blood flow was calculated from the first-pass time activity curves generated over the kidney and aorta and expressed as a percentage of cardiac output (RBF/CO). Renal transplant blood flow is clearly diminished in ATN, similar as in acute rejection, and significantly related to the graft function, what means that RBF/CO value could potentially serve as a prognostic factor in the graft function recovery from ATN.

Effect of warming and flow rate conditions of blood warmers on red blood cell integrity.

Science.gov (United States)

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

2016-11-01

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.

MR measurement of coronary arterial blood flow velocity. Evaluation of age, stenosis and drugs as factors affecting coronary blood flow

International Nuclear Information System (INIS)

Taoka, Yoshiaki; Harada, Masafumi; Nishitani, Hiromu; Yukinaka, Michiko; Nomura, Masahiro

1998-01-01

Coronary arterial blood flow velocity was measured using MRI. Two types of phase contrast methods were used for the measurements, one of which exhibited good resolving power whereas the other provided more distinct images acquired while the subject patients held their breath. Before measuring coronary arterial blood flow velocity, accuracy of the two phase contrast methods was evaluated using a phantom. The results obtained with both methods largely agreed with the values obtained using the phantom. Using both methods, the patterns of coronary arterial blood flow over one cardiac cycle were essentially identical. A peak was noted in late systole or in early diastole in the right coronary artery, whereas in the left coronary artery, a peak was noted somewhat later in diastole. In healthy volunteers, no significant difference in the maximal flow velocity in the coronary arteries was found from one age group to another. Among patients with coronary arterial stenosis, coronary arterial blood flow velocity central to the area of stenosis was lower than that observed in the healthy volunteers. Coronary arterial blood flow velocity was observed to decrease after administration of isosorbide dinitrate and increased following administration of nifedipine. (author)

Light therapy modulates serotonin levels and blood flow in women with headache. A preliminary study.

Science.gov (United States)

Tomaz de Magalhães, Miriam; Núñez, Silvia Cristina; Kato, Ilka Tiemy; Ribeiro, Martha Simões

2016-01-01

In this study, we looked at the possible effects of low-level laser therapy (LLLT) on blood flow velocity, and serotonin (5-HT) and cholinesterase levels in patients with chronic headache associated with temporomandibular disorders (TMD). LLLT has been clinically applied over the past years with positive results in analgesia and without the report of any side effects. The understanding of biological mechanisms of action may improve clinical results and facilitate its indication. Ten patients presenting headache associated with TMD completed the study. An 830-nm infrared diode laser with power of 100 mW, exposure time of 34 s, and energy of 3.4 J was applied on the tender points of masseter and temporal muscle. Blood flow velocity was determined via ultrasound Doppler velocimetry before and after laser irradiation. The whole blood 5-HT and cholinesterase levels were evaluated three days before, immediately, and three days after laser irradiation. Pain score after treatment decreased to a score of 5.8 corresponding to 64% of pain reduction (P  0.05). Our findings indicated that LLLT regulates blood flow in the temporal artery after irradiation and might control 5-HT levels in patients suffering with tension-type headache associated to TMD contributing to pain relief. © 2016 by the Society for Experimental Biology and Medicine.

Cerebral blood flow and cerebrovascular response to acetazolamide in patients with chronic alcoholism

OpenAIRE

Oishi, M; Mochizuki, Y; Takasu, T

1997-01-01

Cerebral blood flow and cerebrovascular response to acetazolamide were studied in 12 patients with chronic alcoholism and 12 age matched healthy controls. Blood flows in the cerebral cortex, thalamus, and putamen were significantly lower in the chronic alcoholic group than in the healthy control group. The increase in blood flow caused by acetazolamide did not show any significant difference between the two groups. These findings suggest that the decreased cerebral blood flow i...

Frequency encoding in renal blood flow regulation

DEFF Research Database (Denmark)

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

2005-01-01

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

X-ray PIV measurements of blood flows without tracer particles

International Nuclear Information System (INIS)

Kim, Guk Bae; Lee, Sang Joon

2006-01-01

We analyzed the non-Newtonian flow characteristics of blood moving in a circular tube flow using an X-ray PIV method and compared the experimental results with hemodynamic models. The X-ray PIV method was improved for measuring quantitative velocity fields of blood flows using a coherent synchrotron X-ray. Without using any contrast media, this method can visualize flow pattern of blood by enhancing the phase-contrast and interference characteristics of blood cells. The enhanced X-ray images were achieved by optimizing the sample-to-scintillator distance, the sample thickness, and hematocrit in detail. The quantitative velocity fields of blood flows inside opaque conduits were obtained by applying a two-frame PIV algorithm to the X-ray images of the blood flows. The measured velocity data show typical features of blood flow such as the yield stress and shear-thinning effects. (orig.)

Subcutaneous blood flow during insulin-induced hypoglycaemia

DEFF Research Database (Denmark)

Hilsted, J; Madsbad, S; Sestoft, L

1982-01-01

Subcutaneous blood flow was measured preceding insulin-induced hypoglycaemia, at the onset of hypoglycaemic symptoms and 2 h later in juvenile diabetics with and without autonomic neuropathy and in normal males. In all groups subcutaneous blood flow decreased at the onset of hypoglycaemic symptom...

Effect of Body Temperature on the Radionuclide Evaluation of Cerebral Blood Flow

International Nuclear Information System (INIS)

Mustafa, S. . E- mail: seham@hsc.edu.kw; Elgazzar, A.H.; Gopinath, S.; Mathew, M.; Khalil, M.

2006-01-01

Changes in regional cerebral blood flow (rCBF) may reflect physiological correlates of the disease state. In neuro-imaging studies, some diseases have frequently been reported to be associated with reduced or increased rCBF. In a previous study we had shown evidence of heat induced vasoconstriction of the carotid artery, which is the main vessel supplying blood to the brain. This vasoconstriction may lead to a decrease in cerebral blood flow in hyperthermic patients. Most radionuclide studies used to assess cerebral blood flow are routinely performed without taking into consideration patients' body temperature. In this regard it may be noted that results of radionuclide cerebral perfusion studies may be affected by hyperthermia, which could lead to false positive studies or misinterpretation of results when they are performed on patients suffering from various cerebrovascular diseases. The objective of the present study was to investigate the importance of body temperature and its effect on the results of radionuclide cerebral perfusion studies. Cerebral blood flow was assessed using Tc-99m hexamethylpropyleneamineoxime (Tc-99m HMPAO) imaging. Baseline scintigraphic images of the brain were obtained in 10 rabbits using a gamma camera equipped with a low energy parallel hole and high resolution collimator interfaced with a computer. Repeat brain studies were performed on the same rabbits at 3 and 6 days after raising the body temperature by 2 deg. C and 4 deg. C respectively using the same imaging protocol. The counts per pixel were determined on control and hyperthermia images. The uptake of Tc-99m HMPAO in the brain was found to be significantly reduced following hyperthermia implying reduction in blood flow. This decrease in cerebral perfusion appears to be variable from region to region, being more in the cerebral hemispheres, frontal areas (olfactory lobes) than in the cerebellum. Based on the results, the authors conclude that a rise in body temperature might

The effect of ultrasound on arterial blood flow: 1. Steady fully developed flow

International Nuclear Information System (INIS)

Bestman, A.R.

1990-12-01

The paper models the effects of ultrasound heating of the tissues and the resultant perturbation on blood flow in the arteries and veins. It is assumed that the blood vessel is rigid and the undisturbed flow is fully developed. Acoustical perturbation on this Poiseuille flow, for the general three-dimensional flow with heat transfer in an infinitely long pipe is considered. Closed form analytical solutions are obtained to the problem. It is discovered that the effects of the ultrasound heating are concentrated at the walls of the blood vessels. (author). 4 refs

Two-Fluid Mathematical Models for Blood Flow in Stenosed Arteries: A Comparative Study

Directory of Open Access Journals (Sweden)

Sankar DS

2009-01-01

Full Text Available The pulsatile flow of blood through stenosed arteries is analyzed by assuming the blood as a two-fluid model with the suspension of all the erythrocytes in the core region as a non-Newtonian fluid and the plasma in the peripheral layer as a Newtonian fluid. The non-Newtonian fluid in the core region of the artery is assumed as a (i Herschel-Bulkley fluid and (ii Casson fluid. Perturbation method is used to solve the resulting system of non-linear partial differential equations. Expressions for various flow quantities are obtained for the two-fluid Casson model. Expressions of the flow quantities obtained by Sankar and Lee (2006 for the two-fluid Herschel-Bulkley model are used to get the data for comparison. It is found that the plug flow velocity and velocity distribution of the two-fluid Casson model are considerably higher than those of the two-fluid Herschel-Bulkley model. It is also observed that the pressure drop, plug core radius, wall shear stress and the resistance to flow are significantly very low for the two-fluid Casson model than those of the two-fluid Herschel-Bulkley model. Hence, the two-fluid Casson model would be more useful than the two-fluid Herschel-Bulkley model to analyze the blood flow through stenosed arteries.

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

DEFF Research Database (Denmark)

Simonsen, L; Bülow, J; Astrup, A

1990-01-01

The effect of a carbohydrate-rich meal on subcutaneous adipose tissue blood flow was studied with and without continuous i.v. infusion of propranolol in healthy volunteers. The subcutaneous adipose tissue blood flow was measured with the 133Xe washout method in three different locations......: 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...

Regional cerebral blood flow in pure dysarthria. A 3D-SSP study

International Nuclear Information System (INIS)

Okamoto, Kensho; Kamogawa, Kenji; Okuda, Bungo; Kawabata, Keita; Tachibana, Hisao

2007-01-01

Pure dysarthria from brain infarction is a rare condition, and its pathophysiology remains unclear. To clarify the underlying mechanism of pure dysarthria, we investigated the lesion sites and regional cerebral blood flow in patients with pure dysarthria. We examined 18 consecutive patients with pure dysarthria (9 men and 9 women; mean age, 71 years) who underwent MRI and cerebral blood flow studies. To visualize the regional cerebral blood flow, we generated Z score images using the three-dimensional stereotactic surface projection (3D-SSP) method with single-photon emission computed tomography (SPECT) and N-isopropyl-p [ 123 I]iodoamphetamine. Data on the brain surface perfusion extracted by the 3D-SSP analysis were compared between the pure dysarthria (PD) patients and 9 control subjects. MRI revealed multiple lacunar infarctions involving the internal capsule and/or corona radiata in 11 patients, left internal capsule-corona radiata infarction in 4 patients, and pontine infarction in 3 patients. SPECT with 3D-SSP demonstrated bilateral frontal cortical hypoperfusion in all patients, particularly in the anterior opercular region. Based on intergroup comparisons, the PD group exhibited pronounced cortical hypoperfusion in the opercular and medial frontal regions, left more than right. In conclusion, pure dysarthria is considered to originate from frontal cortical hypoperfusion, mainly in the anterior opercular and medial frontal regions, which is probably due to interruption of the corticosubcortical neural networks relevant to speech expression and articulation. In addition, it is suggested that left hemispheric lesions may make a greater contribution to the development of pure dysarthria than do right ones. (author)

Renal blood flow in sepsis: a complex issue

OpenAIRE

Molitoris, Bruce A

2005-01-01

The clinical complexity of sepsis and the regional variability in renal blood flow present a difficult challenge for the clinician or investigator in understanding the role and clinical importance of reduced blood flow in the pathophysiology of sepsis-induced acute renal failure. Understanding the role of regional microvasculature flow and interactions between endothelium and white blood cells in the local delivery of oxygen and substrates is of critical importance. Therefore, measuring total...

In vivo analysis of physiological 3D blood flow of cerebral veins

Energy Technology Data Exchange (ETDEWEB)

Schuchardt, Florian; Schroeder, Laure; Baeuerle, Jochen; Harloff, Andreas [University Medical Centre, Department of Neurology, Freiburg (Germany); Anastasopoulos, Constantin [University Medical Center, Department of Neuropaediatrics and Muscle Disorders, Freiburg (Germany); University Medical Centre, Department of Neuroradiology, Freiburg (Germany); Markl, Michael [Northwestern University, Department of Radiology, Feinberg School of Medicine and McCormick School of Engineering, Chicago, IL (United States); Hennemuth, Anja; Drexl, Johann [Fraunhofer MEVIS, Bremen (Germany); Valdueza, Jose M. [Neurological Center, Segeberger Kliniken, Bad Segeberg (Germany); Mader, Irina [University Medical Centre, Department of Neuroradiology, Freiburg (Germany)

2015-08-15

To visualize and quantify physiological blood flow of intracranial veins in vivo using time-resolved, 3D phase-contrast MRI (4D flow MRI), and to test measurement accuracy. Fifteen healthy volunteers underwent repeated ECG-triggered 4D flow MRI (3 Tesla, 32-channel head coil). Intracranial venous blood flow was analysed using dedicated software allowing for blood flow visualization and quantification in analysis planes at the superior sagittal, straight, and transverse sinuses. MRI was evaluated for intra- and inter-observer agreement and scan-rescan reproducibility. Measurements of the transverse sinuses were compared with transcranial two-dimensional duplex ultrasound. Visualization of 3D blood flow within cerebral sinuses was feasible in 100 % and within at least one deep cerebral vein in 87 % of the volunteers. Blood flow velocity/volume increased along the superior sagittal sinus and was lower in the left compared to the right transverse sinus. Intra- and inter-observer reliability and reproducibility of blood flow velocity (mean difference 0.01/0.02/0.02 m/s) and volume (mean difference 0.0002/-0.0003/0.00003 l/s) were good to excellent. High/low velocities were more pronounced (8 % overestimation/9 % underestimation) in MRI compared to ultrasound. Four-dimensional flow MRI reliably visualizes and quantifies three-dimensional cerebral venous blood flow in vivo and is promising for studies in patients with sinus thrombosis and related diseases. (orig.)

Effects of neuropeptide Y on regulation of blood flow rate in canine myocardium

DEFF Research Database (Denmark)

Svendsen, Jesper Hastrup; Sheikh, S P; Jørgensen, J

1990-01-01

The effect of neuropeptide Y (NPY) on tension development was examined in isolated canine coronary arteries, and the effects on local myocardial blood flow rate were studied in open-chest anesthetized dogs by the local 133Xe washout technique. By immunohistochemistry, numerous NPY-like immunoreac......The effect of neuropeptide Y (NPY) on tension development was examined in isolated canine coronary arteries, and the effects on local myocardial blood flow rate were studied in open-chest anesthetized dogs by the local 133Xe washout technique. By immunohistochemistry, numerous NPY......+. In contrast, intracoronary NPY (0.01-10 micrograms) induced a considerable degree of vasoconstriction; the reduction of blood flow rate was dose related, with a maximum reduction to 52% of control values. The effect of intracoronary NPY (1 microgram) on maximally relaxed arterioles elicited by 30 s...... of ischemia was studied in separate experiments during reactive hyperemia. NPY induced a decrease in maximum blood flow during reactive hyperemia (166.6 vs. 214.6% of preocclusive blood flow rate, mean values; P = 0.05), an increase in the cumulative excess blood flow (61.0 vs. 35.3 ml/100 g; P = 0...

Regional differences in the skin blood flow at various sites of the body studied by xenon 133

International Nuclear Information System (INIS)

Tsuchida, Y.

1987-01-01

Normal skin blood flow was measured by the xenon 133 clearance method at different anatomic sites of the body and the following results were obtained. First, the skin blood flow of the face and anterior chest was significantly greater than that of the deltoid region (P less than 0.01). The skin blood flow of the dorsal side of the hand and foot was significantly lower than that of the deltoid region (P less than 0.01). A tendency was observed for the skin blood flow to decrease gradually from the upper part of the body to the lower part of the body. For example, the ratio of the highest value at the face to the lowest value at the dorsal side of the foot was about 2.5:1, indicating a remarkable difference among the various sites of the body. The skin blood flow at the dorsum of the hand was significantly higher by about 25.4 percent than that of the foot (P less than 0.01). Second, the skin blood flow at the left side of the deltoid region was higher by about 5 percent than that of the right side (P less than 0.01). Bilateral comparison of the skin blood flow at the dorsal side of the hand and foot showed that the values were almost the same on the left and right

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

International Nuclear Information System (INIS)

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

1986-01-01

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 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

In vivo evaluation of femoral blood flow measured with magnetic resonance

International Nuclear Information System (INIS)

Henriksen, O.; Staahlberg, F.; Thomsen, C.; Moegelvang, J.; Persson, B.; Lund Univ.

1989-01-01

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, 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 arrest. The mean T2 of non-flowing blood was found to be 105±31 ms. The femoral blood flow ranged between 0 and 643 ml/min measured with MRI and between 280 and 531 ml/min measured by the indicator dilution technique. There was thus poor agreement between the two methods. The results indicate 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. (orig.)

Sequential topographical portrayal of myocardial blood flow

Energy Technology Data Exchange (ETDEWEB)

Richeson, J.F.; Waag, R.C.; Zwierzynski, D.; Schenk, E.A. (Univ. of Rochester School of Medicine and Dentistry, NY (USA))

1989-08-01

Methods to portray myocardial blood flow in a two-dimensional continuum are advantageous in that they allow blood flow history to be overlaid on histological or histochemical descriptions of the consequences of ischemia. We describe here autoradiographic methods that allow such portrayals at three separate times during the evolution of ischemic injury. A computer-based image-analysis system was used to derive such flow maps by taking advantage of the physical characteristics of radioactive isotopes.

Intraoperative laser speckle contrast imaging for monitoring cerebral blood flow: results from a 10-patient pilot study

Science.gov (United States)

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

2012-02-01

Monitoring cerebral blood flow (CBF) during neurosurgery can provide important physiological information for a variety of surgical procedures. Although multiple intraoperative vascular monitoring technologies are currently available, a quantitative method that allows for continuous monitoring is still needed. Laser speckle contrast imaging (LSCI) is an optical imaging method with high spatial and temporal resolution that has been widely used to image CBF in animal models in vivo. In this pilot clinical study, we adapted a Zeiss OPMI Pentero neurosurgical microscope to obtain LSCI images by attaching a camera and a laser diode. This LSCI adapted instrument has been used to acquire full field flow images from 10 patients during tumor resection procedures. The patient's ECG was recorded during acquisition and image registration was performed in post-processing to account for pulsatile motion artifacts. Digital photographs confirmed alignment of vasculature and flow images in four cases, and a relative change in blood flow was observed in two patients after bipolar cautery. The LSCI adapted instrument has the capability to produce real-time, full field CBF image maps with excellent spatial resolution and minimal intervention to the surgical procedure. Results from this study demonstrate the feasibility of using LSCI to monitor blood flow during neurosurgery.

Upper limit of cerebral blood flow autoregulation in experimental renovascular hypertension in the baboon

DEFF Research Database (Denmark)

Strandgaard, S; Jones, J V; MacKenzie, E T

1975-01-01

The effect of arterial hypertension on cerebral blood flow was studied by the intracarotid 133Xe clearance method in baboons. The arterial blood pressure was raised in gradual steps with angiotensin. Baboons with renal hypertension of 8-12 weeks duration were studied along with normotensive baboons....... In initially normotensive baboons, cerebral blood flow remained constant until the mean arterial blood pressure had risen to the range of 140 to 154 mm Hg; thereafter cerebral blood flow increased with each rise in mean arterial blood pressure. In the chronically hypertensive baboons, cerebral blood flow...... remained constant until the mean arterial blood pressure had been elevated to the range of 155 to 169 mm Hg. Thus, in chronic hypertension it appears that there are adaptive changes in the cerebral circulation which may help to protect the brain from further increases in arterial blood pressure....

Results and validity of renal blood flow measurements using Xenon 133

International Nuclear Information System (INIS)

Serres, P.; Danet, B.; Guiraud, R.; Durand, D.; Ader, J.L.

1975-01-01

The renal blood flow was measured by external recording of the xenon 133 excretion curve. The study involved 45 patients with permanent high blood pressure and 7 transplant patients. The validity of the method was checked on 10 dogs. From the results it seems that the cortical blood flow, its fraction and the mean flow rate are the most representative of the renal haemodynamics parameters, from which may be established the repercussions of blood pressure on kidney vascularisation. Experiments are in progress on animals to check the compartment idea by comparing injections into the renal artery and into various kidney tissues in situ [fr

[Ultrasonographic study of blood flow in the renal arteries of patients with arterial hypertension].

Science.gov (United States)

Makarenko, E S; Dombrovskiĭ, V I; Nelasov, N Iu

2012-01-01

Vascular duplex ultrasound duplex with simultaneous ECG registration was made to estimate the quantitative and time parameters of blood flow in the renal arteries with grade 1-2 arterial hypertension. There were increases in vascular resistance indices and acceleration phase index and a reduction in systolic phase index. There were correlations of the time parameters of blood flow in the renal arteries with age and lipidogram values.

Preliminary studies of regional cerebral blood flow changes in patients with leukoaraiosis

International Nuclear Information System (INIS)

Li Yaming; Ren Yan; He Qiu

1997-01-01

PURPOSE: To investigate changes of regional cerebral blood flow (rCBF) in leukoaraiosis (LA) lesion and cortical regions and analyse the relation between rCBF changes and dementia. METHODS: Regional cerebral blood flow perfusion imaging with SPECT was performed in 49 patients with subcortical multiple cerebral infarction, including 24 cases company LA [LA(+)], 25 cases not company LA[LA(-)] and 10 normal subjects. The relative analysis was made between rCBF changes and cognitive scores. RESULTS: Compared the LA(+) with control, the rCBFs in frontal, parietal, temporal cortexes and LA lesion significantly decreased (P<0.05). The rCBF of frontal, parietal cortexes and LA lesions was also significantly decreased (P<0.05) compared with LA(-) groups. The cognitive scores were significantly related with rCBF changes in frontal cortex and LA lesion (r = 0.765, P<0.01 and r = 0.439, P<0.05). CONCLUSION: In patients with subcortical multiple cerebral infarction company LA lesion, there were extensive ischemic hypoperfusion changes in the cortical regions and LA lesion, which may response to decreased cerebral function and had certain relationship with dementia. The examination with SPECT cerebral blood flow perfusion imaging had unique advantage and value

Effects of respiratory muscle work on respiratory and locomotor blood flow during exercise.

Science.gov (United States)

Dominelli, Paolo B; Archiza, Bruno; Ramsook, Andrew H; Mitchell, Reid A; Peters, Carli M; Molgat-Seon, Yannick; Henderson, William R; Koehle, Michael S; Boushel, Robert; Sheel, A William

2017-11-01

What is the central question of this study? Does manipulation of the work of breathing during high-intensity exercise alter respiratory and locomotor muscle blood flow? What is the main finding and its importance? We found that when the work of breathing was reduced during exercise, respiratory muscle blood flow decreased, while locomotor muscle blood flow increased. Conversely, when the work of breathing was increased, respiratory muscle blood flow increased, while locomotor muscle blood flow decreased. Our findings support the theory of a competitive relationship between locomotor and respiratory muscles during intense exercise. Manipulation of the work of breathing (WOB) during near-maximal exercise influences leg blood flow, but the effects on respiratory muscle blood flow are equivocal. We sought to assess leg and respiratory muscle blood flow simultaneously during intense exercise while manipulating WOB. Our hypotheses were as follows: (i) increasing the WOB would increase respiratory muscle blood flow and decrease leg blood flow; and (ii) decreasing the WOB would decrease respiratory muscle blood flow and increase leg blood flow. Eight healthy subjects (n = 5 men, n = 3 women) performed a maximal cycle test (day 1) and a series of constant-load exercise trials at 90% of peak work rate (day 2). On day 2, WOB was assessed with oesophageal balloon catheters and was increased (via resistors), decreased (via proportional assist ventilation) or unchanged (control) during the trials. Blood flow was assessed using near-infrared spectroscopy optodes placed over quadriceps and the sternocleidomastoid muscles, coupled with a venous Indocyanine Green dye injection. Changes in WOB were significantly and positively related to changes in respiratory muscle blood flow (r = 0.73), whereby increasing the WOB increased blood flow. Conversely, changes in WOB were significantly and inversely related to changes in locomotor blood flow (r = 0.57), whereby decreasing the

Collateral sources of costal and crural diaphragmatic blood flow

International Nuclear Information System (INIS)

Lockhat, D.; Magder, S.; Roussos, C.

1985-01-01

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

In-vivo brain blood flow imaging based on laser speckle contrast imaging and synchrotron radiation microangiography

International Nuclear Information System (INIS)

Miao, Peng; Feng, Shihan; Zhang, Qi; Lin, Xiaojie; Xie, Bohua; Liu, Chenwei; Yang, Guo-Yuan

2014-01-01

Abstract In-vivo imaging of blood flow in the cortex and sub-cortex is still a challenge in biological and pathological studies of cerebral vascular diseases. Laser speckle contrast imaging (LSCI) only provides cortex blood flow information. Traditional synchrotron radiation micro-angiography (SRA) provides sub-cortical vasculature information with high resolution. In this study, a bolus front-tracking method was developed to extract blood flow information based on SRA. Combining LSCI and SRA, arterial blood flow in the ipsilateral cortex and sub-cortex was monitored after experimental intracerebral hemorrhage of mice. At 72 h after injury, a significant blood flow increase was observed in the lenticulostriate artery along with blood flow decrease in cortical branches of the middle cerebral artery. This combined strategy provides a new approach for the investigation of brain vasculature and blood flow changes in preclinical studies. (paper)

Vascular structure determines pulmonary blood flow distribution

Science.gov (United States)

Hlastala, M. P.; Glenny, R. W.

1999-01-01

Scientific knowledge develops through the evolution of new concepts. This process is usually driven by new methodologies that provide observations not previously available. Understanding of pulmonary blood flow determinants advanced significantly in the 1960s and is now changing rapidly again, because of increased spatial resolution of regional pulmonary blood flow measurements.

Cluster headache: transcranial Doppler ultrasound and regional cerebral blood flow studies

International Nuclear Information System (INIS)

Dahl, A.; Russell, D.; Nyberg-Hansen, R.; Rootwelt, K.

1990-01-01

Transcranial Doppler and rCBF examinations were carried out in 25 cluster headache patients. Spontaneous glyceryl trinitrate (nitroglycerin) provoked attacks were accompanied by a bilateral decrease in middle cerebral artery blood flow velocities. This decrease was more pronounced on the symptomatic side, but the difference did not reach statistical significance. Mean hemispheric blood flow and rCBF were within normal limits during provoked attacks and similar to those found when patients were attack-free. During cluster periods middle cerebral artery velocities were significantly higher on the symptomatic side. Glyceryl trinitrate caused a bilateral middle cerebral artery velocity decrease which was significantly greater on the symptomatic side. Attacks provoked by glyceryl trinitrate appeared to begin when the vasodilatory effect of this substance was received. 17 refs., 2 figs., 5 tabs

Blood Cell Interactions and Segregation in Flow

OpenAIRE

Munn, Lance L.; Dupin, Michael M.

2008-01-01

For more than a century, pioneering researchers have been using novel experimental and computational approaches to probe the mysteries of blood flow. Thanks to their efforts, we know that blood cells generally prefer to migrate to the axis of flow, that red and white cells segregate in flow, and that cell deformability and their tendency to reversibly aggregate contribute to the non-Newtonian nature of this unique fluid. All of these properties have beneficial physiological consequences, allo...

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.

1986-05-01

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.

Effect of fluid friction on interstitial fluid flow coupled with blood flow through solid tumor microvascular network.

Science.gov (United States)

Sefidgar, Mostafa; Soltani, M; Raahemifar, Kaamran; Bazmara, Hossein

2015-01-01

A solid tumor is investigated as porous media for fluid flow simulation. Most of the studies use Darcy model for porous media. In Darcy model, the fluid friction is neglected and a few simplified assumptions are implemented. In this study, the effect of these assumptions is studied by considering Brinkman model. A multiscale mathematical method which calculates fluid flow to a solid tumor is used in this study to investigate how neglecting fluid friction affects the solid tumor simulation. The mathematical method involves processes such as blood flow through vessels and solute and fluid diffusion, convective transport in extracellular matrix, and extravasation from blood vessels. The sprouting angiogenesis model is used for generating capillary network and then fluid flow governing equations are implemented to calculate blood flow through the tumor-induced capillary network. Finally, the two models of porous media are used for modeling fluid flow in normal and tumor tissues in three different shapes of tumors. Simulations of interstitial fluid transport in a solid tumor demonstrate that the simplifications used in Darcy model affect the interstitial velocity and Brinkman model predicts a lower value for interstitial velocity than the values that Darcy model predicts.

Analysis of blood flow patterns in aortic aneurysm by cine magnetic resonance imaging

International Nuclear Information System (INIS)

Matsuoka, Hiroshi

1993-01-01

Cine MRI (0.5 T) using rephased gradient echo technique was performed to study the patterns of blood flow in the aortic aneurysm of 16 patients with aortic aneurysm, and the data were compared with those of 5 healthy volunteers. In the transaxial section, the blood flow in normal aorta appeared as homogeneous high intensity during systole. On the other hand, the blood flow in the aneurysm appeared as inhomogeneous flow enhancement with flow void. In the sagittal scan, the homogeneous flow enhancement in a normal aorta was also observed during systole and its apex of flow enhancement was 'taper'. The blood flow patterns in the aneurysm were classified as 'irregular', 'zonal', 'eddy', and 'obscure' depending on the contrast of flow enhancement and flow void. Their apexes were 'taper' or 'round'. The blood flow patterns in the aneurysm were related to the size of aneurysm. In patients with a large size 'aneurysm, their flow patterns were 'eddy' or 'obscure' and the flow enhancement was 'round'. On the other hand, in patients with a small size aneurysm, their flow patterns were 'irregular' or 'zonal', and their flow enhancement was 'taper'. Though the exact mechanism of abnormal flow patterns in an aortic aneurysm remains to be determined, cine MRI gives helpful informations in assessing blood flow dynamics in the aneurysm. (author)

Nephron blood flow dynamics measured by laser speckle contrast imaging

DEFF Research Database (Denmark)

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

2011-01-01

Tubuloglomerular feedback (TGF) has an important role in autoregulation of renal blood flow and glomerular filtration rate (GFR). Because of the characteristics of signal transmission in the feedback loop, the TGF undergoes self-sustained oscillations in single-nephron blood flow, GFR, and tubular...... simultaneously. The interacting nephron fields are likely to be more extensive. We have turned to laser speckle contrast imaging to measure the blood flow dynamics of 50-100 nephrons simultaneously on the renal surface of anesthetized rats. We report the application of this method and describe analytic...... pressure and flow. Nephrons interact by exchanging electrical signals conducted electrotonically through cells of the vascular wall, leading to synchronization of the TGF-mediated oscillations. Experimental studies of these interactions have been limited to observations on two or at most three nephrons...

Comparative studies of D2 receptors and cerebral blood flow in hemi-Parkinsonism rats

International Nuclear Information System (INIS)

Lin Yansong; Lin Xiangtong

2000-01-01

Objective: To study the relationship between dopamine D 2 receptors and cerebral blood flow in hemi-Parkinsonism rats. Methods: Hemi-Parkinsonism rats were made by stereotaxic 6-hydroxy dopamine (6-OH-DA) lesions in substantia nigra and ventral tegmental area, apomorphine (Apo) which could induce the successful model rat to rotate toward the intact side was used to select the rat models, 125 I-IBZM in vivo autoradiography and 99 Tc m -HMPAO regional cerebral biodistribution analysis were used to study D 2 receptors and cerebral blood flow. The HPLC-ECD was used to measure striatum DA and its metabolite content . Results: the lesioned side striatum DA and its metabolites homovanillic acid (HVA) 3,4-dihyroxy-phenylacetic acid (DOPAC) reduced significantly than that of the intact side and pseudo-operated group, striatum/cerebellum 125 I-IBZM uptake ratio was 8.04 +- 0.71 in lesioned side of hemi-Parkinsonism rats, significantly increased compared with the intact side and the pseudo-operated group (P 0.05). Conclusions: the 6-OH-DA lesioned side DA content decreased significantly and thus induced a compensative up-regulation of striatum D 2 receptor binding sites in hemi-Parkinsonism rats, which show good correlation with rotation behavior induced by Apo. Comparing with cerebral blood flow, D 2 receptor reflected by IBZM seems to be more specific and earlier to detect the cerebral functional impairment in experimental hemi-Parkinsonism

The effect of rapid decompression on femur blood flow of rabbits

International Nuclear Information System (INIS)

Yu Shaoning; Tian Wuxun; Zhu Xiangqi

1997-01-01

PURPOSE: To study the influence of regional blood flow in femur trochanter (FT) of rabbits' under rapid decompression after exposure to hyperbaric air. METHODS: Rabbits were placed in a hyperbaric chamber and exposed to the pressure of 0.5 MPa for 1.5 h, and the pressure was reduced to the atmosphere pressure at a uniform rate of 0.03 mPa/min. The regional blood flow of FT in rabbits were measured with 133 Xe washout methods. RESULTS: The normal average regional blood flow in left and right FT were 14.5 +- 1.7 and 14.1 +- 1.9 ml/(min·100g) respectively. After exposure to hyperbaric air with rapid decompression, the average regional blood flow of left and right FT were 11.1 +- 1.2 and 10.5 +- 1.6 ml/(min·100g) respectively. But the symptoms of dysbarism in these rabbits were various each other. CONCLUSIONS: After being exposed to hyperbaric air with rapid decompression, the blood flow of rabbits' femur trochanter were noticeably reduced

In vivo evaluation of femoral blood flow measured with magnetic resonance

DEFF Research Database (Denmark)

Henriksen, O; Ståhlberg, F; Thomsen, C

1989-01-01

, 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...... arrest. The mean T2 of non-flowing blood was found to be 105 +/- 31 ms. The femoral blood flow ranged between 0 and 643 ml/min measured with MRI and between 280 and 531 ml/min measured by the indicator dilution technique. There was thus poor agreement between the two methods. The results indicate......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...

Cerebral blood flow in migraine and cortical spreading depression

Energy Technology Data Exchange (ETDEWEB)

Lauritzen, M.

1987-01-01

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).

Distribution of the pulmonary blood flow measured by ECT

Energy Technology Data Exchange (ETDEWEB)

Maeda, H.; Itoh, H.; Todo, Y.; Ishii, Y.; Mukai, T. (Kyoto Univ. (Japan). Hospital)

1981-05-01

Distributions of pulmonary blood flow per unit lung volume were observed by using the combination of Tc-99m-MAA and radionuclide CT. Administration of Tc-99m-MAA to the patients were performed in sitting position. Ten patients were studied with this method. In nine patients, the blood flow distribution was greater in the direction of the gravity, namely, more blood flow in the lower than the upper lung region. In six patients were demonstrated the relation between blood flow and the vertical distance described by West et al. Thus, it was possible to evaluate the arterial and venous pressures of the lung with the estimated pressure of 4.15 +- 1.93 cmH/sub 2/O and -5.55 +- 2.48 cmH/sub 2/O in relation to the angle of Louis. The agreement was reasonably well with that reported by Butler and Paley. Three patients had pulmonary hypertension with the distribution of monotonous increase, of which slope was similar to that of zone III in other six patients. The last patient with COPD had quite different distribution from other nine patients.

Splanchnic blood flow and hepatic glucose production in exercising humans

DEFF Research Database (Denmark)

Bergeron, R; Kjaer, M; Simonsen, L

2001-01-01

The study examined the implication of the renin-angiotensin system (RAS) in regulation of splanchnic blood flow and glucose production in exercising humans. Subjects cycled for 40 min at 50% maximal O(2) consumption (VO(2 max)) followed by 30 min at 70% VO(2 max) either with [angiotensin-converti......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......-converting enzyme (ACE) blockade] or without (control) administration of the ACE inhibitor enalapril (10 mg iv). Splanchnic blood flow was estimated by indocyanine green, and splanchnic substrate exchange was determined by the arteriohepatic venous difference. Exercise led to an approximately 20-fold increase (P ...-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...

A numerical analysis on the curved bileaflet Mechanical Heart Valve (MHV) : leaflet motion and blood flow in an elastic blood vessel

International Nuclear Information System (INIS)

Bang, Jin Seok; Kim, Chang Nyung; Choi, Choeng Ryul

2005-01-01

In blood flow passing through the Mechanical Heart Valve (MHV) and elastic blood vessel, hemolysis and platelet activation causing thrombus formation can be seen owing to the shear stress in the blood. Also, fracture and deformation of leaflets can be observed depending on the shape and material properties of the leaflets which is opened and closed in a cycle. Hence, comprehensive study is needed on the hemodynamics which is associated with the motion of leaflet and elastic blood vessel in terms of fluid-structure interaction. In this paper, a numerical analysis has been performed for a three-dimensional pulsatile blood flow associated with the elastic blood vessel and curved bileaflet for multiple cycles in light of fluid-structure interaction. From this analysis fluttering phenomenon and rebound of the leaflet have been observed and recirculation and regurgitation have been found in the flow fields of the blood. Also, the pressure distribution and the radial displacement of the elastic blood vessel have been obtained. The motion of the leaflet and flow fields of the blood have shown similar tendency compared with the previous experiments carried out in other studies. The present study can contribute to the design methodology for the curved bileaflet mechanical heart valve. Furthermore, the proposed fluid-structure interaction method will be effectively used in various fields where the interaction between fluid flow and structure are involved

Gender differences in regional cerebral blood flow

International Nuclear Information System (INIS)

Gur, R.E.; Gur, R.C.

1990-01-01

Gender differences have been noted in neurobehavioral studies. The 133xenon inhalation method for measuring regional cerebral blood flow (rCBF) can contribute to the understanding of the neural basis of gender differences in brain function. Few studies have examined gender differences in rCBF. In studies of normal subjects, women have higher rates of CBF than men, and this is related to age. Usually by the sixth decade men and women have similar flow rates. Fewer studies on rCBF in schizophrenia have examined sex differences. The pattern of higher flows for females maintains, but its correlates with gender differences in clinical as well as other parameters of brain function remain to be examined

Influence of cold-water immersion on limb blood flow after resistance exercise.

Science.gov (United States)

Mawhinney, Chris; Jones, Helen; Low, David A; Green, Daniel J; Howatson, Glyn; Gregson, Warren

2017-06-01

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 lower (55%) than the control post-immersion (P water similarly reduce femoral artery and cutaneous blood flow responses but not muscle temperature following resistance exercise.

Evaluation of 133Xe clearance curves in the study of lingual blood flow in dogs

International Nuclear Information System (INIS)

Fazekas, A.; Posch, E.; Harsing, L.

1979-01-01

Lingual blood flow was studied in dogs by the 133 Xe clearance technique under control conditions, during epinephrine infusion and in response to a combined treatment with regitin and epinephrine. The composite washout curves recorded during control conditions could be resolved into three monoexponential components. It is suggested that the steep initial slope (component I) is caused by the fraction of blood that perfuses the A-V anastomoses of the tongue. Components II and III appear to indicate the perfusion rate of lingual mucosa and musculature, respectively. The disappearance of component I due to the effect of epinephrine infusion might indicate the closure of arterio-venous anastomoses containing alpha receptors. Regitin pretreatment could prevent the closure of the arterio-venous anastomoses elicited by epinephrine infusion. The beta receptor stimulating activity of epinephrine might account for the augmentation of blood flow to lingual musculature. (orig.) 891 AJ/orig. 892 BRE [de

Caffeine and human cerebral blood flow: A positron emission tomography study

International Nuclear Information System (INIS)

Cameron, O.G.; Modell, J.G.; Hariharan, M.

1990-01-01

Positron emission tomography (PET) was used to quantify the effect of caffeine on whole brain and regional cerebral blood flow (CBF) in humans. A mean dose of 250 mg of caffeine produced approximately a 30% decrease in whole brain CBF; regional differences in caffeine effect were not observed. Pre-caffeine CBF strongly influenced the magnitude of the caffeine-induced decrease. Caffeine decreased p a CO 2 and increased systolic blood pressure significantly; the change in p a CO 2 did not account for the change in CBF. Smaller increases in diastolic blood pressure, heart rate, plasma epinephrine and norepinephrine, and subjectively reported anxiety were also observed

Caffeine and human cerebral blood flow: A positron emission tomography study

Energy Technology Data Exchange (ETDEWEB)

Cameron, O.G.; Modell, J.G.; Hariharan, M. (Univ. of Michigan Medical Center, Ann Arbor (USA))

1990-01-01

Positron emission tomography (PET) was used to quantify the effect of caffeine on whole brain and regional cerebral blood flow (CBF) in humans. A mean dose of 250 mg of caffeine produced approximately a 30% decrease in whole brain CBF; regional differences in caffeine effect were not observed. Pre-caffeine CBF strongly influenced the magnitude of the caffeine-induced decrease. Caffeine decreased p{sub a}CO{sub 2} and increased systolic blood pressure significantly; the change in p{sub a}CO{sub 2} did not account for the change in CBF. Smaller increases in diastolic blood pressure, heart rate, plasma epinephrine and norepinephrine, and subjectively reported anxiety were also observed.

Myocardial blood flow during induced aortic hypertension in dogs

International Nuclear Information System (INIS)

Thai, B.N.; Levesque, M.J.; Nerem, R.M.

1986-01-01

Myocardial blood flow was measured in anesthetized dogs during control conditions and under conditions where the aortic pressure was increased due to aortic constriction or during infusion. Blood flow was measured using the radioactive microsphere technique. Radioactive microspheres (15 m Ce-141, Sr-85, and Sc-46) were injected under control, aortic constriction and arterenol infusion in four dogs and under control conditions in two others. All microsphere injections were performed under stabilized conditions. It was found that coronary blood flow rose by 80% during aortic constriction and by 158% during arterenol infusion (P < 0.05). This increase in blood flow was not uniform throughout the heart, and higher increases were observed in the middle and apex regions of the left ventricle. Furthermore, under hypertension the increase in blood flow in LAD (left anterior descending) perfused territories was slightly higher than that in CFX (left circumflex) perfused territories

[Microcirculatory blood and lymph flow examination in eyelid skin by laser Doppler flowmetry].

Science.gov (United States)

Safonova, T N; Kintyukhina, N P; Sidorov, V V; Gladkova, O V; Reyn, E S

to study normal blood and lymph microcirculation of the upper and lower eyelids in different age groups. The study included 108 volunteers (216 eyes) aged from 20 to 80 years with no signs of changes in anterior segment structures, who were grouped by age ranges (20-30 years, 31-40 years, 41-50 years, 51-60 years, 61-70 years, and 71-80 years) into 6 groups equal in gender and quantitative composition. In all volunteers, microcirculation of the upper and lower eyelids was examined by laser Doppler flowmetry (LDF) ('LASMA MC-1' peripheral blood and lymph flow analyzer and 'LASMA MC' laser diagnostic complex, LASMA LLC). The average perfusion changes in blood and lymph flow as well as blood and lymph flow oscillations were analyzed. Blood and lymph flow in the microvasculature of the upper and lower eyelids is variable and depends on neither the age, nor gender of the test subject. On LDF-gram, every increase in amplitude of blood flow corresponds to a decrease in that of lymph flow. The non-invasive method of LDF expands our diagnostic capabilities as it enables assessment of not only blood, but also lymph flow. The data obtained can serve as a starting point for exploring microcirculation in different age groups in the presence of different pathological processes.

Arteriovenous oscillations of the redox potential: Is the redox state influencing blood flow?

Science.gov (United States)

Poznanski, Jaroslaw; Szczesny, Pawel; Pawlinski, Bartosz; Mazurek, Tomasz; Zielenkiewicz, Piotr; Gajewski, Zdzislaw; Paczek, Leszek

2017-09-01

Studies on the regulation of human blood flow revealed several modes of oscillations with frequencies ranging from 0.005 to 1 Hz. Several mechanisms were proposed that might influence these oscillations, such as the activity of vascular endothelium, the neurogenic activity of vessel wall, the intrinsic activity of vascular smooth muscle, respiration, and heartbeat. These studies relied typically on non-invasive techniques, for example, laser Doppler flowmetry. Oscillations of biochemical markers were rarely coupled to blood flow. The redox potential difference between the artery and the vein was measured by platinum electrodes placed in the parallel homonymous femoral artery and the femoral vein of ventilated anesthetized pigs. Continuous measurement at 5 Hz sampling rate using a digital nanovoltmeter revealed fluctuating signals with three basic modes of oscillations: ∼ 1, ∼ 0.1 and ∼ 0.01 Hz. These signals clearly overlap with reported modes of oscillations in blood flow, suggesting coupling of the redox potential and blood flow. The amplitude of the oscillations associated with heart action was significantly smaller than for the other two modes, despite the fact that heart action has the greatest influence on blood flow. This finding suggests that redox potential in blood might be not a derivative but either a mediator or an effector of the blood flow control system.

Effects of endothelium-derived nitric oxide on skin and digital blood flow in humans.

Science.gov (United States)

Coffman, J D

1994-12-01

The effects of NG-monomethyl-L-arginine (L-NMMA) on total finger and forearm, and dorsal finger and forearm skin, blood flows were studied in the basal state and during reflex sympathetic vasoconstriction in normal subjects. Total flows were measured by venous occlusion plethysmography and skin flows by laser-Doppler flowmetry (LDF). L-NMMA in doses of 2, 4, and 8 microM/min given by constant infusion via a brachial artery catheter significantly decreased finger blood flow, forearm blood flow, and vascular conductances. At 8 microM/min, total finger blood flow decreased 38.4% and forearm blood flow decreased 24.8%. Dorsal finger and forearm skin LDF were also significantly decreased (25 and 37% at 8 microM/min). Body cooling significantly decreased finger blood flow (73.6%), vascular conductance, and finger LDF (59.7%). L-NMMA had no effect on total finger blood flow or dorsal finger LDF during body cooling. Nitric oxide or related compounds contribute to the basal dilator tone of the dorsal finger and forearm skin but not during reflex sympathetic vasoconstriction.

Regional cerebral blood flow measurement in brain tumors

International Nuclear Information System (INIS)

Izunaga, Hiroshi; Hirota, Yoshihisa; Takahashi, Mutsumasa; Fuwa, Isao; Kodama, Takafumi; Matsukado, Yasuhiko

1986-01-01

The regional cerebral blood flow (CBF) was determined on seventeen patients with brain tumors. Ring type single photon emission CT (SPECT) was used following intravenous injection of 133 Xe. Case materials included eleven meningiomas and six malignant gliomas. Evaluation was performed with emphasis on the following points; 1. Correlation of the flow data within tumors to the angiographic tumor stains, 2. Influence of tumors on the cerebral blood flow of the normal brain tissue, 3. Correlation between degree of peripheral edema and the flow data of the affected hemispheres. There was significant correlation between flow data within tumors and angiographic tumor stains in meningiomas. Influence of tumors on cerebral blood flow of the normal tissue was greater in meningiomas than in gliomas. There was negative correlation between the degree of peripheral edema and the flow data of the affected hemisphere. It has been concluded that the measurement of CBF in brain tumors is a valuable method in evaluation of brain tumors. (author)

Regional cerebral blood flow measurement in brain tumors

Energy Technology Data Exchange (ETDEWEB)

Izunaga, Hiroshi; Hirota, Yoshihisa; Takahashi, Mutsumasa; Fuwa, Isao; Kodama, Takafumi; Matsukado, Yasuhiko

1986-10-01

The regional cerebral blood flow (CBF) was determined on seventeen patients with brain tumors. Ring type single photon emission CT (SPECT) was used following intravenous injection of /sup 133/Xe. Case materials included eleven meningiomas and six malignant gliomas. Evaluation was performed with emphasis on the following points; 1. Correlation of the flow data within tumors to the angiographic tumor stains, 2. Influence of tumors on the cerebral blood flow of the normal brain tissue, 3. Correlation between degree of peripheral edema and the flow data of the affected hemispheres. There was significant correlation between flow data within tumors and angiographic tumor stains in meningiomas. Influence of tumors on cerebral blood flow of the normal tissue was greater in meningiomas than in gliomas. There was negative correlation between the degree of peripheral edema and the flow data of the affected hemisphere. It has been concluded that the measurement of CBF in brain tumors is a valuable method in evaluation of brain tumors.

The influence of external compression on muscle blood flow during exercise

International Nuclear Information System (INIS)

Styf, J.

1990-01-01

Intramuscular pressures and muscle blood flow were measured in the anterior tibial muscle during dynamic concentric exercise in 14 subjects. Pressures were recorded by the microcapillary infusion method and muscle blood flow by the 133-Xenon clearance technique. Muscle blood flow during constant exercise decreased from 34.5 (SD = 10.3) to 10.6 (SD = 4.9) ml/100 g/min (P less than 0.001) when muscle relaxation pressure was increased from 13.5 (SD = 2.7) to 39.9 (SD = 9.0) mm Hg by external compression. Muscle relaxation pressure during exercise is the intramuscular pressure between contractions. External compression of the lower limb during exercise impedes muscle blood flow by increasing muscle relaxation pressure. The experimental model seems suitable to study the influence of external compression by knee braces on intramuscular pressure during exercise

Synchrotron X-ray PIV Technique for Measurement of Blood Flow Velocity

International Nuclear Information System (INIS)

Kim, Guk Bae; Lee, Sang Joon; Je, Jung Ho

2007-01-01

Synchrotron X-ray micro-imaging method has been used to observe internal structures of various organisms, industrial devices, and so on. However, it is not suitable to see internal flows inside a structure because tracers typically employed in conventional optical flow visualization methods cannot be detectable with the X-ray micro-imaging method. On the other hand, a PIV (particle image velocimetry) method which has recently been accepted as a reliable quantitative flow visualization technique can extract lots of flow information by applying digital image processing techniques However, it is not applicable to opaque fluids such as blood. In this study, we combined the PIV method and the synchrotron X-ray micro-imaging technique to compose a new X-ray PIV technique. Using the X-ray PIV technique, we investigated the optical characteristics of blood for a coherent synchrotron X-ray beam and quantitatively visualized real blood flows inside an opaque tube without any contrast media. The velocity field information acquired would be helpful for investigating hemorheologic characteristics of the blood flow

CHARACTERIZATION OF RENAL BLOOD FLOW REGULATION BASED ON WAVELET COEFFICIENTS

DEFF Research Database (Denmark)

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

2010-01-01

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

Determination of myocardial blood flow by videodensitometry

International Nuclear Information System (INIS)

Erikson, U.; Helmius, G.; Hennig, K.; Johansson, L.; Enghoff, E.; Ruhn, G.

1981-01-01

Videodensitometry has hitherto been used as a tool for measuring regional blood flow in the kidneys and lungs by means of the well known Stewart Hamilton curve (wash-out) technique. This preliminary report suggests the possibility of using this method to measure coronary blood flow. Thirty-six patients, 29 of whom had angina pectoris, underwent videodensitometry in connection with coronary angiography. (orig.) [de

Cerebral blood flow and intracranial pulsatility studied with MRI: measurement, physiological and pathophysiological aspects

International Nuclear Information System (INIS)

Waahlin, Anders

2012-01-01

During each cardiac cycle pulsatile arterial blood inflates the vascular bed of the brain, forcing cerebrospinal fluid (CSF) and venous blood out of the cranium. Excessive arterial pulsatility may be part of a harmful mechanism causing cognitive decline among elderly. Additionally, restricted venous flow from the brain is suggested as the cause of multiple sclerosis. Addressing hypotheses derived from these observations requires accurate and reliable investigational methods. This work focused on assessing the pulsatile waveform of cerebral arterial, venous and CSF flows. The overall aim of this dissertation was to explore cerebral blood flow and intracranial pulsatility using MRI, with respect to measurement, physiological and pathophysiological aspects.Two-dimensional phase contrast magnetic resonance imaging (2D PCMRI) was used to assess the pulsatile waveforms of cerebral arterial, venous and CSF flow. The repeatability was assessed in healthy young subjects. The 2D PCMRI measurements of cerebral arterial, venous and CSF pulsatility were generally repeatable but the pulsatility decreased systematically during the investigation. A method combining 2D PCMRI measurements with invasive CSF infusion tests to determine the magnitude and distribution of compliance within the craniospinal system was developed and applied in a group of healthy elderly. The intracranial space contained approximately two thirds of the total craniospinal compliance. The magnitude of craniospinal compliance was less than suggested in previous studies. The vascular hypothesis for multiple sclerosis was tested. Venous drainage in the internal jugular veins was compared between healthy controls and multiple sclerosis patients using 2D PCMRI. For both groups, a great variability in the internal jugular flow was observed but no pattern specific to multiple sclerosis could be found. Relationships between regional brain volumes and potential biomarkers of intracranial cardiac-related pulsatile

Cerebral blood flow and intracranial pulsatility studied with MRI: measurement, physiological and pathophysiological aspects

Energy Technology Data Exchange (ETDEWEB)

Waahlin, Anders

2012-07-01

During each cardiac cycle pulsatile arterial blood inflates the vascular bed of the brain, forcing cerebrospinal fluid (CSF) and venous blood out of the cranium. Excessive arterial pulsatility may be part of a harmful mechanism causing cognitive decline among elderly. Additionally, restricted venous flow from the brain is suggested as the cause of multiple sclerosis. Addressing hypotheses derived from these observations requires accurate and reliable investigational methods. This work focused on assessing the pulsatile waveform of cerebral arterial, venous and CSF flows. The overall aim of this dissertation was to explore cerebral blood flow and intracranial pulsatility using MRI, with respect to measurement, physiological and pathophysiological aspects.Two-dimensional phase contrast magnetic resonance imaging (2D PCMRI) was used to assess the pulsatile waveforms of cerebral arterial, venous and CSF flow. The repeatability was assessed in healthy young subjects. The 2D PCMRI measurements of cerebral arterial, venous and CSF pulsatility were generally repeatable but the pulsatility decreased systematically during the investigation. A method combining 2D PCMRI measurements with invasive CSF infusion tests to determine the magnitude and distribution of compliance within the craniospinal system was developed and applied in a group of healthy elderly. The intracranial space contained approximately two thirds of the total craniospinal compliance. The magnitude of craniospinal compliance was less than suggested in previous studies. The vascular hypothesis for multiple sclerosis was tested. Venous drainage in the internal jugular veins was compared between healthy controls and multiple sclerosis patients using 2D PCMRI. For both groups, a great variability in the internal jugular flow was observed but no pattern specific to multiple sclerosis could be found. Relationships between regional brain volumes and potential biomarkers of intracranial cardiac-related pulsatile

Blood flow in curved pipe with radiative heat transfer

International Nuclear Information System (INIS)

Ogulu, A.; Bestman, A.R.

1992-03-01

Blood flow in a curved pipe such as the aorta is modelled in this study. The aorta is modelled as a curved pipe of slowly varying cross-section. Asymptotic series expansions about a small parameter δ, which is a measure of the curvature ratio is employed to obtain the velocity and temperature distributions. The study simulates the effect of radio-frequency heating, for instance during physiotherapy, on the flow of blood in the cardiovascular system assuming an external constant pressure gradient; and our results agree very well with results obtained by Pedley. (author). 9 refs, 2 figs

Renal blood flow and oxygenation drive nephron progenitor differentiation.

Science.gov (United States)

Rymer, Christopher; Paredes, Jose; Halt, Kimmo; Schaefer, Caitlin; Wiersch, John; Zhang, Guangfeng; Potoka, Douglas; Vainio, Seppo; Gittes, George K; Bates, Carlton M; Sims-Lucas, Sunder

2014-08-01

During kidney development, the vasculature develops via both angiogenesis (branching from major vessels) and vasculogenesis (de novo vessel formation). The formation and perfusion of renal blood vessels are vastly understudied. In the present study, we investigated the regulatory role of renal blood flow and O2 concentration on nephron progenitor differentiation during ontogeny. To elucidate the presence of blood flow, ultrasound-guided intracardiac microinjection was performed, and FITC-tagged tomato lectin was perfused through the embryo. Kidneys were costained for the vasculature, ureteric epithelium, nephron progenitors, and nephron structures. We also analyzed nephron differentiation in normoxia compared with hypoxia. At embryonic day 13.5 (E13.5), the major vascular branches were perfused; however, smaller-caliber peripheral vessels remained unperfused. By E15.5, peripheral vessels started to be perfused as well as glomeruli. While the interior kidney vessels were perfused, the peripheral vessels (nephrogenic zone) remained unperfused. Directly adjacent and internal to the nephrogenic zone, we found differentiated nephron structures surrounded and infiltrated by perfused vessels. Furthermore, we determined that at low O2 concentration, little nephron progenitor differentiation was observed; at higher O2 concentrations, more differentiation of the nephron progenitors was induced. The formation of the developing renal vessels occurs before the onset of blood flow. Furthermore, renal blood flow and oxygenation are critical for nephron progenitor differentiation. Copyright © 2014 the American Physiological Society.

Directly measuring spinal cord blood flow and spinal cord perfusion pressure via the collateral network: correlations with changes in systemic blood pressure.

Science.gov (United States)

Kise, Yuya; Kuniyoshi, Yukio; Inafuku, Hitoshi; Nagano, Takaaki; Hirayasu, Tsuneo; Yamashiro, Satoshi

2015-01-01

During thoracoabdominal surgery in which segmental arteries are sacrificed over a large area, blood supply routes from collateral networks have received attention as a means of avoiding spinal cord injury. The aim of this study was to investigate spinal cord blood supply through a collateral network by directly measuring spinal cord blood flow and spinal cord perfusion pressure experimentally. In beagle dogs (n = 8), the thoracoabdominal aorta and segmental arteries L1-L7 were exposed, and a temporary bypass was created for distal perfusion. Next, a laser blood flow meter was placed on the spinal dura mater in the L5 region to measure the spinal cord blood flow. The following were measured simultaneously when the direct blood supply from segmental arteries L2-L7 to the spinal cord was stopped: mean systemic blood pressure, spinal cord perfusion pressure (blood pressure within the aortic clamp site), and spinal cord blood flow supplied via the collateral network. These variables were then investigated for evidence of correlations. Positive correlations were observed between mean systemic blood pressure and spinal cord blood flow during interruption of segmental artery flow both with (r = 0.844, P flow with and without distal perfusion (r = 0.803, P network from outside the interrupted segmental arteries, and high systemic blood pressure (∼1.33-fold higher) was needed to obtain the preclamping spinal cord blood flow, whereas 1.68-fold higher systemic blood pressure was needed when distal perfusion was halted. Spinal cord blood flow is positively correlated with mean systemic blood pressure and spinal cord perfusion pressure under spinal cord ischemia caused by clamping a wide range of segmental arteries. In open and endovascular thoracic and thoracoabdominal surgery, elevating mean systemic blood pressure is a simple and effective means of increasing spinal cord blood flow, and measuring spinal cord perfusion pressure seems to be useful for monitoring

Cerebral Blood Flow Measurement Using fMRI and PET: A Cross-Validation Study

Directory of Open Access Journals (Sweden)

Jean J. Chen

2008-01-01

Full Text Available An important aspect of functional magnetic resonance imaging (fMRI is the study of brain hemodynamics, and MR arterial spin labeling (ASL perfusion imaging has gained wide acceptance as a robust and noninvasive technique. However, the cerebral blood flow (CBF measurements obtained with ASL fMRI have not been fully validated, particularly during global CBF modulations. We present a comparison of cerebral blood flow changes (ΔCBF measured using a flow-sensitive alternating inversion recovery (FAIR ASL perfusion method to those obtained using H2O15 PET, which is the current gold standard for in vivo imaging of CBF. To study regional and global CBF changes, a group of 10 healthy volunteers were imaged under identical experimental conditions during presentation of 5 levels of visual stimulation and one level of hypercapnia. The CBF changes were compared using 3 types of region-of-interest (ROI masks. FAIR measurements of CBF changes were found to be slightly lower than those measured with PET (average ΔCBF of 21.5±8.2% for FAIR versus 28.2±12.8% for PET at maximum stimulation intensity. Nonetheless, there was a strong correlation between measurements of the two modalities. Finally, a t-test comparison of the slopes of the linear fits of PET versus ASL ΔCBF for all 3 ROI types indicated no significant difference from unity (P>.05.

Determination of splenic blood flow by inhalation of radioactive rare gases

Energy Technology Data Exchange (ETDEWEB)

Huchzermeyer, H; Schmitz-Feuerhake, I; Reblin, T [Medizinische Hochschule Hannover (Germany, F.R.). Abt. fuer Nuklearmedizin und Spezielle Biophysik; Medizinische Hochschule Hannover (Germany, F.R.). Abt. fuer Gastroenterologie)

1977-10-01

We have evaluated the /sup 133/Xenon inhalation method for the determination of splenic blood flow. In twenty-two healthy persons the blood flow was on average 109 +- 4 ml/100 g x min, which is equivalent to a total blood flow of about 170 ml/min. In patients with chronic fatty liver hepatitis specific blood flow was reduced (81 +- 10 ml/100 g x min) as it was in patients with cirrhotic liver without splenomegaly (75 +- 2 ml/100 g x min.). With increasing weight of the spleen, the total blood flow rises, although specific blood flow is low. Our results obtained by the /sup 133/Xenon inhalation method are similar to results obtained by others using intraarterial injection of tracer gas. The advantages of the inhalation method as a non-traumatic method are: 1) the stress for the patient is very small; 2) blood flow measurements can be repeated within short periods of time. We consider for the present the /sup 133/Xenon inhalation method to be the method of choice for the determination of the splenic blood flow.

Study on the tomographic cerebral blood flow measurement with stable xenon inhalation

International Nuclear Information System (INIS)

Kimura, Kazumoto; Ueda, Yasuichi; Nagai, Masakatsu; Segawa, Hiromu.

1983-01-01

This study was conducted to obtain quantitative values of regional cerebral blood flow (rCBF) by serial CT scanning during non radioactive xenon (Xe) inhalation. The present study provided not only rCBF map but build up rate (k) map and partition coefficient (lambda) map both in normal and pathological brain tissues. The lambda map can not be readily obtained by radioisotope (RI) or positron emission CT method. These maps provided high resolution enough to identify white matter, gray matter and even deep structure of the brain such as caudate nucles, thalums and internal capsule, and were directly compared with CT image. Resolution of each map permited visualization of small area as much as 1-3 mm in diameter. Blood flow for gray matter was 82+-11 and that for white matter was 24+-5 ml/100 g/min in seven normal subjects. The inhalation time of Xe gas and the scanning interval influenced the k, lambda, and rCBF map, respectively. In order to visualize the distribution of white matter on lambda map, it required more than 20 min inhalation of the gas. The scanning interval for good map was every 3 min in the first 9 min and every 5 min in the later period. (author)

Measurement of regional hepatic blood flow by scintiphotosplenoportography

Energy Technology Data Exchange (ETDEWEB)

Kashiwagi, T; Kimura, K; Kamada, T; Abe, H [Osaka Univ. (Japan). Dept. of Radiology and Nuclear Medicine

1978-08-01

A new technique for estimating regional hepatic blood flow using the inert gas washout technique and scintillation camera following injection of /sup 133/Xe into the spleen is presented. This technique is easily, rapidly and repeatedly performed and permits the measurement of nutrient hepatic tissue blood flow. Measurement of regional hepatic blood flow in right and/or left lobes was performed in 28 patients. In all but one patient the right lobar flow value was equal to or greater than the left one. The right lobar flow was 86.20 +- 12.83 ml/100 gm/min in 3 patients without liver disease, 75.12 +- 14.54 ml/100 gm/min in 12 with chronic hepatitis and 51.24 +- 17.13 ml/100 gm/min in 11 with liver cirrhosis. This result suggests that hepatic tissue blood flow is significantly decreased in patients with liver cirrhosis. Scintillation camera images of initial xenon distribution in combination with monitor of washout curves over the liver also provide more information on the presence of extra- and intrahepatic shunts. Therefore, this technique appears to be clinically useful in evaluation of hemodynamic phenomena associated with liver diseases.

Blood flow distribution in dog gastrocnemius muscle at rest and during stimulation

International Nuclear Information System (INIS)

Piiper, J.; Pendergast, D.R.; Marconi, C.; Meyer, M.; Heisler, N.; Cerretelli, P.

1985-01-01

The distribution of blood flow within the isolated perfused dog gastrocnemius muscle (weight 100-240 g) was studied by intra-arterial injection of radioactively labeled microspheres (diameter 15 micron) at rest and during supramaximal stimulation to rhythmic isotonic tetanic contractions of varied frequency against varied loads. After the experiment the muscle was cut into 180-250 pieces of approximately 0.75 g each, and the blood flow to each muscle piece was determined from its radioactivity. The inhomogeneity of blood flow was represented as the frequency distribution of the ratios of regional specific blood flow, i.e., blood flow per unit tissue weight of the piece, QR, to the overall specific blood flow of the muscle, Q. The QR/Q values for the individual pieces of a muscle were found to vary widely both at rest and during stimulation. With rising work load the frequency distribution had a tendency to broaden and flatten, indicating increasing perfusion inhomogeneity. On the average of the experiments, there was no significant difference in specific blood flow between the three anatomic components of the gastrocnemius (lateral and medial heads of gastrocnemius and flexor digitorum superficialis) nor between the superficial and deep portions within these anatomic components, only the distal third of the muscle was relatively less perfused compared with the proximal two-thirds. The considerable inhomogeneity of blood flow as revealed by microsphere embolization and by other methods is expected to exert important limiting effects on local O 2 supply, particularly during exercise

Cutaneous blood flow rate in areas with and without arteriovenous anastomoses during exercise

DEFF Research Database (Denmark)

Midttun, M.; Sejrsen, Per

1998-01-01

Arteriovenous anastomoses, capillaries, cutaneous bllod flow rate, exercise, finger blood flow, skin blood flow......Arteriovenous anastomoses, capillaries, cutaneous bllod flow rate, exercise, finger blood flow, skin blood flow...

The feasibility of measuring renal blood flow using transesophageal echocardiography in patients undergoing cardiac surgery.

Science.gov (United States)

Yang, Ping-Liang; Wong, David T; Dai, Shuang-Bo; Song, Hai-Bo; Ye, Ling; Liu, Jin; Liu, Bin

2009-05-01

There is no reliable method to monitor renal blood flow intraoperatively. In this study, we evaluated the feasibility and reproducibility of left renal blood flow measurements using transesophageal echocardiography during cardiac surgery. In this prospective noninterventional study, left renal blood flow was measured with transesophageal echocardiography during three time points (pre-, intra-, and postcardiopulmonary bypass) in 60 patients undergoing cardiac surgery. Sonograms from 6 subjects were interpreted by 2 blinded independent assessors at the time of acquisition and 6 mo later. Interobserver and intraobserver reproducibility were quantified by calculating variability and intraclass correlation coefficients. Patients with Doppler angles of >30 degrees (20 of 60 subjects) were eliminated from renal blood flow measurements. Left renal blood flow was successfully measured and analyzed in 36 of 60 (60%) subjects. Both interobserver and intraobserver variability were renal blood flow measurements were good to excellent (intraclass correlation coefficients 0.604-0.999). Left renal arterial luminal diameter for the pre, intra, and postcardiopulmonary bypass phases, ranged from 3.8 to 4.1 mm, renal arterial velocity from 25 to 35 cm/s, and left renal blood flow from 192 to 299 mL/min. In patients undergoing cardiac surgery, it was feasible in 60% of the subjects to measure left renal blood flow using intraoperative transesophageal echocardiography. The interobserver and intraobserver reproducibility of renal blood flow measurements was good to excellent.

Effect of fluocinolone acetonide cream on human skin blood flow

International Nuclear Information System (INIS)

Chimoskey, J.E.; Holloway, A. Jr.; Flanagan, W.J.

1975-01-01

Blood flow rate was measured in the forearm skin of human subjects exposed to ultraviolet irradiation. Blood flow was determined by the 133 Xe disappearance technique 18 hr after ultraviolet (UV) irradiation with a Westinghouse RS sunlamp held 10 inches from the skin for 10 min. Ultraviolet irradiation caused skin blood flow to increase. Application of fluocinolone acetonide cream, 0.025 percent, 4 times in the 16 hr following UV irradiation had no effect on either control skin blood flow or the UV-induced hyperemia

Dose-response studies of Ropivacaine in blood flow of upper extremity after supraclavicular block: a double-blind randomized controlled study.

Science.gov (United States)

Li, Ting; Ye, Qiguang; Wu, Daozhu; Li, Jun; Yu, Jingui

2017-12-02

The sympathetic block of upper limb leading to increased blood flow has important clinical implication in microvascular surgery. However, little is known regarding the relationship between concentration of local anesthetic and blood flow of upper limb. The aim of this dose-response study was to determine the ED 50 and ED 95 of ropivacaine in blood flow after supraclavicular block (SB). Patients undergoing upper limb surgery and supraclavicular block were randomly assigned to receive 30ml ropivacaine in concentrations of 0.125%(A Group), 0.2%(B Group), 0.25%(C Group), 0.375%(D Group), 0.5%(E Group), or 0.75%(F Group) (n=13 per group). All patients received supraclavicular block (SB). Time average maximum velocity (TAMAX), cross-sectional area (CSA) of brachial artery and skin temperatures (T s ) were measured repeatedly at the same marked points, they were taken at baseline (before block, t 0 ) and at 30min after SB (t 1 ). Blood flow(BF) = TAMAX× CSA×60 sec.. Relative blood flow (ΔBF) = BF t1 / BF t0 . Success of SB was assessed simultaneously. Supplementary anesthesia and other adverse events (AE) were recorded. Significant increase in TAMAX, CSA, BF and T s were seen in all concentration groups at t 1 comparing with t 0 (Pblock were 0.18/0.33% (0.15-0.21/0.27-0.51), R 2 =0.904. The dose-response curve between SB ropivacaine and the changes of BF was determined. The ED 50 /ED 95 of ropivacaine of ΔBF are 0.35/1.94% (0.25-0.45/0.83-4.52). TAMAX, CSA and BF consistently increased with ropivacaine concentration. The maximal sympathetic block needs higher concentration than that complete sensation block needs which may benefit for microvascular surgery. Clinicaltrials.gov NCT02139982 . Retrospectively registered (Date of registration: May, 2014).

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

Spatial Temporal Image Correlation Spectroscopy (STICS) for Flow Analysis with Application for Blood Flow Mapping

International Nuclear Information System (INIS)

Rossow, Molly; Gratton, Enrico; Mantulin, William M.

2009-01-01

It is important for surgeons to be able to measure blood flow in exposed arterioles during surgery. We report our progress in the development of an optical technique that will measure blood flow in surgically exposed blood vessels and enable previously difficult measurements. By monitoring optical fluctuations, the optical technique, based on Spatial Temporal Image Correlation (STICS), will directly measure the velocity of micron-scale particles--such as red blood cells. It will complement existing technology and provide qualitative measurements that were not previously possible. It relies on the concept that blood, when viewed on a small enough scale, is an inhomogeneous substance. Individual blood cells passing between a near-infrared light source and a detector will cause fluctuations in the transmitted optical signal. The speed, direction, and flow pattern of blood cells can be determined from these optical fluctuations. We present a series of computer simulations and experiments on phantom and animal systems to test this technique's ability to map complex flow patterns.

Flow rate calibration to determine cell-derived microparticles and homogeneity of blood components.

Science.gov (United States)

Noulsri, Egarit; Lerdwana, Surada; Kittisares, Kulvara; Palasuwan, Attakorn; Palasuwan, Duangdao

2017-08-01

Cell-derived microparticles (MPs) are currently of great interest to screening transfusion donors and blood components. However, the current approach to counting MPs is not affordable for routine laboratory use due to its high cost. The current study aimed to investigate the potential use of flow-rate calibration for counting MPs in whole blood, packed red blood cells (PRBCs), and platelet concentrates (PCs). The accuracy of flow-rate calibration was investigated by comparing the platelet counts of an automated counter and a flow-rate calibrator. The concentration of MPs and their origins in whole blood (n=100), PRBCs (n=100), and PCs (n=92) were determined using a FACSCalibur. The MPs' fold-changes were calculated to assess the homogeneity of the blood components. Comparing the platelet counts conducted by automated counting and flow-rate calibration showed an r 2 of 0.6 (y=0.69x+97,620). The CVs of the within-run and between-run variations of flow-rate calibration were 8.2% and 12.1%, respectively. The Bland-Altman plot showed a mean bias of -31,142platelets/μl. MP enumeration revealed both the difference in MP levels and their origins in whole blood, PRBCs, and PCs. Screening the blood components demonstrated high heterogeneity of the MP levels in PCs when compared to whole blood and PRBCs. The results of the present study suggest the accuracy and precision of flow-rate calibration for enumerating MPs. This flow-rate approach is affordable for assessing the homogeneity of MPs in blood components in routine laboratory practice. Copyright © 2017 Elsevier Ltd. All rights reserved.

Total hepatofugal portal blood flow in cirrhosis demonstrated by transhepatic portography

Energy Technology Data Exchange (ETDEWEB)

Burcharth, F; Aagaard, J

1988-01-01

We investigated 108 patients with cirrhosis of the liver and portal hypertension by percutaneous transhepatic portography to demonstrate the occurrence and frequency of total hepatofugal portal blood flow. Sixteen patients (14.8%) had a total hepatofugal portal blood flow. The aetiology of portal hypertension and the portal pressure did not differ from that in the group of patients with hepatopetal portal blood flow. A significantly higher percentage of patients in the group with hepatofugal flow had gastro-oesophageal varices (P < 0.025). All patients with varices had bled. Half of the patients in the group with hepatofugal blood flow had a false splenoportographic diagnosis of portal vein thrombosis. In conclusion, total hepatofugal postal blood flow exists more often than hitherto assumed. Hepatofugal blood flow does not relieve portal hypertension nor prevent development of gastro-oesophageal varices or bleeding.

Muscle blood flow at onset of dynamic exercise in humans.

Science.gov (United States)

Rådegran, G; Saltin, B

1998-01-01

To evaluate the temporal relationship between blood flow, blood pressure, and muscle contractions, we continuously measured femoral arterial inflow with ultrasound Doppler at onset of passive exercise and voluntary, one-legged, dynamic knee-extensor exercise in humans. Blood velocity and inflow increased (P dicrotic and diastolic blood pressure notches, respectively. Mechanical hindrance occurred (P dicrotic notch. The increase in blood flow (Q) was characterized by a one-component (approximately 15% of peak power output), two-component (approximately 40-70% of peak power output), or three-component exponential model (> or = 75% of peak power output), where Q(t) = Qpassive + delta Q1.[1 - e-(t - TD1/tau 1)]+ delta Q2.[1 - e-(t - TD2/tau 2)]+ delta Q3.[1 - e-(t - TD3/tau 3)]; Qpassive, the blood flow during passive leg movement, equals 1.17 +/- 0.11 l/min; TD is the onset latency; tau is the time constant; delta Q is the magnitude of blood flow rise; and subscripts 1-3 refer to the first, second, and third components of the exponential model, respectively. The time to reach 50% of the difference between passive and voluntary asymptotic blood flow was approximately 2.2-8.9 s. The blood flow leveled off after approximately 10-150 s, related to the power outputs. It is concluded that the elevation in blood flow with the first duty cycle(s) is due to muscle mechanical factors, but vasodilators initiate a more potent amplification within the second to fourth contraction.

A study of light scattering of mononuclear blood cells with scanning flow cytometry

International Nuclear Information System (INIS)

Zharinov, Alexey; Tarasov, Peter; Shvalov, Alexander; Semyanov, Konstantin; Bockstaele, Dirk R. van; Maltsev, Valeri

2006-01-01

This study describes the measurement of light scattering of human mononuclear blood cells, the development of an appropriate optical model for those cells, and solution of the inverse light-scattering problem. The angular dependency of light-scattering intensity of mononuclear blood cells was experimentally measured by means of scanning flow cytometry. A sphere consisting of several concentric homogeneous layers with different refractive indices was tested as an optical model for mononuclear blood cells. A five-layer model has given the best agreement between experimental and theoretical light-scattering profiles. The inverse light-scattering problem was solved for a five-layer model with an optimization procedure that allows one to retrieve cell parameters: cell size relates to the outer diameter of the fifth layer; size of the nucleus relates to the outer diameter of the third layer. Mean values of cell size, nuclear size, refractive indices of nucleus and cellular cytoplasm were determined for blood monocytes and lymphocytes

Clinical study of color Doppler sonography in Graves' disease blood flow changes after thyroid arteries embolization

International Nuclear Information System (INIS)

Zhuang Wenquan; Li Weiduo; Yang Jianyong; Chen Wei; Huang Yonghui; Guo Wenbo; Li Jiaping

2003-01-01

Objective: To study the color doppler image characteristics of thyroid arteries pre- and post-interventional procedure and to assess the clinical efficacy in Gnaves' disease. Methods: 11 from 31 patients diagnosed as Graves' disease undertaken thyroid arteries embolization, were analyzed. Color Doppler sonography was applied to monitor the pre-and post- procedure thyroid size and diameters of thyroid arteries. Power Doppler was used to detect the Vmax, Vmin, RI and blood flow. Results: After thyroid arteries embolization, the size and vascularity of thyroids were reduced. The thyroid arteries showed shrinkage and stoppage blood flow at the embolized site. The changes of RI, blood parameters of Vmax, Vmin and diameters of the thyroid arteries pre- and post-procedure turned out to be statistically significant for clinical restriction. Conclusion: The color Doppler sonography plays an important role for preoperative diagnosis and predicting the prognosis

EFFICACY OF LASER PULSE FREQUENCIES ON BLOOD FLOW IN TYPE 2 DIABETIC PATIENTS

Directory of Open Access Journals (Sweden)

Amir Nazih Wadee

2017-04-01

Full Text Available Background: Research reports had noted an apparent increase in cutaneous and deep blood flow as a result of low-intensity laser therapy (LLLT in normal subjects. The purpose of te study was to investigate the effective laser pulse frequency either (200 or 2000 Hz on improving blood flow in type 2 diabetic patients. Forty-five diabetic patients selected from out clinic of Kasr El-Aini Hospital, Cairo University assigned randomly into three groups. The blood flow volume, blood flow velocity and caliper of the blood vessel were evaluated before laser application and after twelve sessions using duplex Doppler ultrasound. Methods: Combined He-Ne and infrared LILT was administered three times a week for twelve sessions at intensity of 3 J, power 500 mW, 808 nm duration 15 min and pulse frequency 200 Hz for group I, 2000 Hz for group II, and sham LILT for group III on the sural artery at posterior aspect of dominant leg. Result: Paired t-test revealed that low pulse frequency (200 Hz LILT produced significant improvement in blood flow volume and blood flow velocity (t= 1.76, p= 0.001 and t= 2.8, p= 0.01 respectively (P<0.05. While there was no significant changes in caliper of the blood vessel of group I, blood flow volume, blood flow velocity or caliper of the blood vessel of group II and group III (t= 2.15, p= 1, t= 2.15, p= 1, t= 1.11 p= 0.31, t= 1.54, p= 0.15, t= 2.51, p= 1, t= 1.21 p= 0.33, t= 1.45, p= 0.15 respectively (P<0.05. ANOVA test in between groups revealed insignificant changes in all pre and post- measures except significant results in blood flow volume and velocity which indicating the superiority of group I on both group II and III by post hoc test. Conclusion: low pulse frequency of LILT (200 Hz could improve blood flow than high pulse frequency (2000 Hz.

Endoscopic retrograde cholangiopancreatography causes reduced myocardial blood flow

DEFF Research Database (Denmark)

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

2002-01-01

BACKGROUND AND STUDY AIMS: Previous studies have shown that up to 50% of healthy patients may develop ST-segment changes during upper gastrointestinal endoscopy. The aim of the study was to evaluate myocardial blood flow in patients during endoscopic retrograde cholangiopancreatography (ERCP...

Neural control of adrenal medullary and cortical blood flow during hemorrhage

International Nuclear Information System (INIS)

Breslow, M.J.; Jordan, D.A.; Thellman, S.T.; Traystman, R.J.

1987-01-01

Hemorrhagic hypotension produces an increase in adrenal medullary blood flow and a decrease in adrenal cortical blood flow. To determine whether changes in adrenal blood flow during hemorrhage are neurally mediated, the authors compared blood flow responses following adrenal denervation (splanchnic nerve section) with changes in the contralateral, neurally intact adrenal. Carbonized microspheres labeled with 153 Gd, 114 In, 113 Sn, 103 Ru, 95 Nb or 46 Se were used. Blood pressure was reduced and maintained at 60 mmHg for 25 min by hemorrhage into a pressurized bottle system. Adrenal cortical blood flow decreased to 50% of control with hemorrhage in both the intact and denervated adrenal. Adrenal medullary blood flow increased to four times control levels at 15 and 25 min posthemorrhage in the intact adrenal, but was reduced to 50% of control at 3, 5, and 10 min posthemorrhage in the denervated adrenal. In a separate group of dogs, the greater splanchnic nerve on one side was electrically stimulated at 2, 5, or 15 Hz for 40 min. Adrenal medullary blood flow increased 5- to 10-fold in the stimulated adrenal but was unchanged in the contralateral, nonstimulated adrenal. Adrenal cortical blood flow was not affected by nerve stimulation. They conclude that activity of the splanchnic nerve profoundly affects adrenal medullary vessels but not adrenal cortical vessels and mediates the observed increase in adrenal medullary blood flow during hemorrhagic hypotension

Evaluation of Renal Blood Flow and Oxygenation in CKD Using Magnetic Resonance Imaging.

Science.gov (United States)

Khatir, Dinah S; Pedersen, Michael; Jespersen, Bente; Buus, Niels H

2015-09-01

Animal studies suggest that progression of chronic kidney disease (CKD) is related to renal hypoxia. With renal blood supply determining oxygen delivery and sodium absorption being the main contributor to oxygen consumption, we describe the relationship between renal oxygenation, renal artery blood flow, and sodium absorption in patients with CKD and healthy controls. Cross-sectional study. 62 stable patients with CKD stages 3 to 4 (mean age, 61±13 [SD] years) and 24 age- and sex-matched controls. CKD versus control status. Renal artery blood flow, tissue oxygenation (relative changes in deoxyhemoglobin concentration of the renal medulla [MR2*] and cortex [CR2*]), and sodium absorption. Renal artery blood flow was determined by phase-contrast magnetic resonance imaging (MRI); MR2* and CR2* were determined by blood oxygen level-dependent MRI. Ultrafiltered and reabsorbed sodium were determined from measured glomerular filtration rate (mGFR) and 24-hour urine collections. mGFR in patients was 37% that of controls (36±15 vs 97±23 mL/min/1.73 m(2); P renal artery blood flow was 72% that of controls (319 vs 443 mL/min; P renal artery blood flow or sodium absorption. Increasing arterial blood oxygen tension by breathing 100% oxygen had very small effects on CR2*, but reduced MR2* in both groups. Only renal artery blood flow was determined and thus regional perfusion could not be related to CR2* or MR2*. In CKD, reductions of mGFR and reabsorbed sodium are more than double that of renal artery blood flow, whereas cortical and medullary oxygenation are within the range of healthy persons. Reduction in glomerular filtration fraction may prevent renal hypoxia in CKD. Copyright © 2015 National Kidney Foundation, Inc. Published by Elsevier Inc. All rights reserved.

Age and gender related differences in aortic blood flow

DEFF Research Database (Denmark)

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

2012-01-01

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

Modeling skin blood flow: a neuro-physiological approach

NARCIS (Netherlands)

Kingma, B.R.M.; Saris, W.H.M.; Frijns, A.J.H.; Steenhoven, van A.A.; Marken Lichtenbelt, van W.D.

2010-01-01

In humans skin blood flow (SBF) plays a major role in body heat loss. Therefore the accuracy of models ofhuman thermoregulation depends for a great deal on their ability to predict skin blood flow. Most SBFmodelsuse body temperatures directly for calculation of skin perfusion. However, humans do not

The measurement of limb blood flow using technetium-labelled red blood cells

International Nuclear Information System (INIS)

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

1986-01-01

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 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. (author)

Heterogeneity of brain blood flow and permeability during acute hypertension

International Nuclear Information System (INIS)

Baumbach, G.L.; Heistad, D.D.

1985-01-01

The purpose of this study was to examine regional autoregulation of blood flow in the brain during acute hypertension. In anesthetized cats severe hypertension increased blood flow more in cerebrum (159%) and cerebellum (106%) than brain stem (58%). In contrast to the heterogeneous autoregulatory response, hypocapnia produced uniform vasoconstriction in the brain. The authors also compared vasodilatation during severe hypertension with vasodilatation during hypercapnia. During hypercapnia, blood flow increased as much in brain stem, as in cerebrum and cerebellum. Thus, regional differences in autoregulation appear to be specific for autoregulatory stimulus and are not secondary to nonspecific differences in vasoconstrictor or vasodilator capacity. To determine whether the blood-brain barrier is more susceptible to hypertensive disruption in regions with less effective autoregulation, permeability of the barrier was quantitated with 125 I-albumin. Severe hypertension produced disruption of the barrier in cerebrum but not in brain stem. Thus, there are parallel differences in effectiveness of autoregulation and susceptibility to disruption of the blood-brain barrier in different regions of the brain

Blood transfusion in preterm infants improves intestinal tissue oxygenation without alteration in blood flow.

Science.gov (United States)

Banerjee, J; Leung, T S; Aladangady, N

2016-11-01

The objective of the study was to investigate the splanchnic blood flow velocity and oximetry response to blood transfusion in preterm infants according to postnatal age. Preterm infants receiving blood transfusion were recruited to three groups: 1-7 (group 1; n = 20), 8-28 (group 2; n = 21) and ≥29 days of life (group 3; n = 18). Superior mesenteric artery (SMA) peak systolic (PSV) and diastolic velocities were measured 30-60 min pre- and post-transfusion using Doppler ultrasound scan. Splanchnic tissue haemoglobin index (sTHI), tissue oxygenation index (sTOI) and fractional tissue oxygen extraction (sFTOE) were measured from 15-20 min before to post-transfusion using near-infrared spectroscopy. The mean pretransfusion Hb in group 1, 2 and 3 was 11, 10 and 9 g/dl, respectively. The mean (SD) pretransfusion SMA PSV in group 1, 2 and 3 was 0·63 (0·32), 0·81 (0·33) and 0·97 (0·40) m/s, respectively, and this did not change significantly following transfusion. The mean (SD) pretransfusion sTOI in group 1, 2 and 3 was 36·7 (19·3), 44·6 (10·4) and 41·3 (10·4)%, respectively. The sTHI and sTOI increased (P transfusion in all groups. On multivariate analysis, changes in SMA PSV and sTOI following blood transfusion were not associated with PDA, feeding, pretransfusion Hb and mean blood pressure. Pretransfusion baseline splanchnic tissue oximetry and blood flow velocity varied with postnatal age. Blood transfusion improved intestinal tissue oxygenation without altering mesenteric blood flow velocity irrespective of postnatal ages. © 2016 International Society of Blood Transfusion.

Usage of CO2 microbubbles as flow-tracing contrast media in X-ray dynamic imaging of blood flows.

Science.gov (United States)

Lee, Sang Joon; Park, Han Wook; Jung, Sung Yong

2014-09-01

X-ray imaging techniques have been employed to visualize various biofluid flow phenomena in a non-destructive manner. X-ray particle image velocimetry (PIV) was developed to measure velocity fields of blood flows to obtain hemodynamic information. A time-resolved X-ray PIV technique that is capable of measuring the velocity fields of blood flows under real physiological conditions was recently developed. However, technical limitations still remained in the measurement of blood flows with high image contrast and sufficient biocapability. In this study, CO2 microbubbles as flow-tracing contrast media for X-ray PIV measurements of biofluid flows was developed. Human serum albumin and CO2 gas were mechanically agitated to fabricate CO2 microbubbles. The optimal fabricating conditions of CO2 microbubbles were found by comparing the size and amount of microbubbles fabricated under various operating conditions. The average size and quantity of CO2 microbubbles were measured by using a synchrotron X-ray imaging technique with a high spatial resolution. The quantity and size of the fabricated microbubbles decrease with increasing speed and operation time of the mechanical agitation. The feasibility of CO2 microbubbles as a flow-tracing contrast media was checked for a 40% hematocrit blood flow. Particle images of the blood flow were consecutively captured by the time-resolved X-ray PIV system to obtain velocity field information of the flow. The experimental results were compared with a theoretically amassed velocity profile. Results show that the CO2 microbubbles can be used as effective flow-tracing contrast media in X-ray PIV experiments.

Quantification of cerebral blood flow via Duplex sonography

International Nuclear Information System (INIS)

Vogl, G.; Pohl, P.; Willeit, J.; Aichner, F.

1987-01-01

An attempt was made to measure quantitatively the total cerebral blood flow by means of Duplex sonography. In a group of healthy young subjects a median value for total cerebral blood flow was obtained amounting to 469 ml/min ± 30%, repeat measurements yielded a maximum deviation of ± 11%. In three patients the values obtained after severe apoplectic insult due to occlusion of the internal carotid artery were definitely below the value of the group of healthy subjects, whereas the value for the total blood flow was in the upper range of normal values in a patient with occlusion of the a. cerebri media. Comparative measurements of the regional cerebral blood flow with xenon 13 yielded in those patients with occlusion of the internal carotid artery a markedly reduced mean flow and in the patient with occlusion of the a. cerebri media a less markedly reduced mean flow. Regionally reduced perfusion was seen in all the four patients in the range of the clinically and computer tomographically well-known ischaemia zone. Thanks to the simplicity of this sonographic examination method it could be a useful decision parameter in determining the indication for a reconstruction of the carotid artery, especially in asymptotic patients. (orig.) [de

Effects of captopril on cerebral blood flow in normotensive and hypertensive rats

International Nuclear Information System (INIS)

Barry, D.I.; Paulson, O.B.; Jarden, J.O.; Juhler, M.; Graham, D.I.; Strandgaard, S.

1984-01-01

Cerebrovascular effects of the angiotensin converting enzyme inhibitor captopril were examined in normotensive and hypertensive rats. Cerebral blood flow was measured with the intracarotid 133 xenon injection method in halothane-anesthetized animals. The blood-brain barrier permeability of captopril (determined with an integral-uptake method) was negligible, the permeability-surface area product in most brain regions being 1 X 10(-5) cm3/g per second, that is, three to four times lower than that of sodium ion. When administered into the cerebral ventricles to bypass the blood-brain barrier, captopril had no effect on cerebral blood flow: furthermore, cerebral blood flow autoregulation (studied by raising and lowering blood pressure) was identical to that in controls. In contrast, when given intravenously, captopril had a marked effect on cerebral blood flow autoregulation--both the lower and upper limits of autoregulation being shifted to a lower pressure (by about 20 to 30 and 50 to 60 mm Hg, respectively), and the autoregulatory range was shortened by about 40 mm Hg. This effect may be ascribed to inhibition of converting enzyme in the cerebral blood vessels rather than within the brain

Computational Analysis of Human Blood Flow

Science.gov (United States)

Panta, Yogendra; Marie, Hazel; Harvey, Mark

2009-11-01

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.

Cerebral blood flow in Binswanger's disease

International Nuclear Information System (INIS)

Kawabata, Keita; Tachibana, Hisao; Sugita, Minoru

1991-01-01

Eight patients with a clinical diagnosis of Binswanger's disease (BD) were evaluated with I-123 IMP SPECT. The SPECT findings were compared with those in 7 other patients with Alzheimer's disease (AD) and 9 normal subjects. The ratios of I-123 IMP in the temporal cortex, thalamus, and basal ganglia to that in the cerebellum were lower in the BD group than the normal group. The BD group had a higher ratio of the occipital cortex/the cerebellum than the control group, suggesting a decreased blood flow in the cerebellum. When I-123 IMP ratio in various areas to that in the occipital cortex was examined, both the BD and AD groups seemed to have a decreased blood flow over the whole cerebrum. The BD group had a lower I-123 IMP uptake in the thalamus and basal ganglia, and the AD group had it in the parietal cortex, relative to the occipital cortex. Blood flow patterns for BD were found to be different from those for AD. This suggests the difference in areas responsible for etiology between BD and AD. (N.K.)

Reduced hypothalamic blood flow after radiation treatment of nasopharyngeal cancer: SPECT studies in 34 patients

International Nuclear Information System (INIS)

Chieng, P.U.; Huang, T.S.; Chang, C.C.; Chong, P.N.; Tien, R.D.; Su, C.T.

1991-01-01

To determine the effect of cranial irradiation on hypothalamic blood flow, the authors performed 44 regional cerebral blood flow studies with 99mTc hexamethyl propyleneamine oxime (HMPAO) single-photon emission CT (SPECT) on four normal volunteers and 34 patients with pathologically proved nasopharyngeal cancer. Twenty-three men and 15 women, 30-65 years old, were divided into four study groups: group 1 served as a control and consisted of four normal volunteers and six patients studied prior to cranial irradiation; group 2 patients had cranial irradiation half a year before the SPECT study (n = 12, one from group 1); group 3 patients were irradiated 1 year before the study (n = 13, three from group 1 and two from group 2); and group 4 patients were irradiated at least 5 years before SPECT imaging (n = 9). Six patients were studied twice. Quantification of the 99mTc-HMPAO brain SPECT studies was done separately by three radiologists to obtain the hypothalamus/occipital (H/O) and hypothalamus/parasagittal (H/P) ratios. Endocrinologic studies were performed in all cases and the hypothalamus-thyrotroph-thyroid, hypothalamus-gonadotroph-testis (ovary), hypothalamus-lactotroph, hypothalamus-somatotroph, and hypothalamus-corticotroph-adrenal axes were evaluated separately. They determined that regional hypothalamic blood flow was reduced after cranial irradiation in patients with nasopharyngeal cancer. The H/O ratio of groups 3 and 4 did not differ from that of group 2 (one-half year after cranial irradiation). The H/O ratio was significantly reduced 6 months and 1 year after cranial irradiation; mean ± SD = 0.5801 ± 0.0829 (p less than .025), 0.5725 ± 0.0791 (p less than .01) versus 0.6477 ± 0.0458 before cranial irradiation, respectively

A new device for intraoperative renal blood flow measurement during open-heart surgery: an experimental study and the clinical pilot study.

Science.gov (United States)

Tirilomis, Theodor; Popov, Aron F; Hanekop, Gunnar G; Braeuer, Anselm; Quintel, Michael; Schoendube, Friedrich A; Friedrich, Martin G

2013-10-01

Renal blood flow (RBF) may vary during cardiopulmonary bypass and low flow may cause insufficient blood supply of the kidney triggering renal failure postoperatively. Still, a valid intraoperative method of continuous RBF measurement is not available. A new catheter combining thermodilution and intravascular Doppler was developed, first calibrated in an in vitro model, and the catheter specific constant was determined. Then, application of the device was evaluated in a pilot study in an adult cardiovascular population. The data of the clinical pilot study revealed high correlation between the flow velocities detected by intravascular Doppler and the RBF measured by thermodilution (Pearson's correlation range: 0.78 to 0.97). In conclusion, the RBF can be measured excellently in real time using the new catheter, even under cardiopulmonary bypass. © 2013 Wiley Periodicals, Inc. and International Center for Artificial Organs and Transplantation.

Coronary blood flow and coronary stenosis correlations in ischemic heart patients

International Nuclear Information System (INIS)

Manukov, I.

2003-01-01

The aim of the study is the assessment of the methodology for the C-TIMI frame count by Gibson for easy and fast determination of the coronary blood flow during a selective coronary angiography. 75 patient have been studied with one-branch affection of the coronary arteries. The criteria for exclusion are: myocardial hypertrophy, valve lesions, myocardial infarction and dyslipidemia. Depending of the characteristics of the coronary stenotic changes, the patients have been divided into two groups: 1) Patients with 'ordinary' stenosis of the coronary artery and 2) Patients with 'complex' stenosis. The severity of the stenotic changes in percents is the same for the two groups - 78%±13% vs 81±12%, respectively. In the first group a pronounced correlation is observed between the severity of the coronary stenosis and the slowing of the coronary blood flow. The 'threshold' stenotic level is 89%. In the second group the lowest value of the coronary stenosis is 73% (p>0.01 vs group 1). No correlation is observed between the severity of the coronary stenosis and the slowing of the coronary blood flow. A conclusion is made that the Gibson method for the assessment of the blood flow is convenient for the daily practice not only for the assessment of the significance of the coronary changes, but also for fast analysis of the achieved reconstruction of the coronary arteries after angioplasty. Additional studies of the significance of the different signs of 'complexity' of the coronary stenosis for the slowing of the blood flow are necessary

Regional cerebral blood flow study with 123I-IMP in patients with degenerative dementia

International Nuclear Information System (INIS)

Ohnishi, T.; Hoshi, H.; Nagamachi, S.; Jinnouchi, S.; Futami, S.; Watanabe, K.; Mitsuyama, Y.

1991-01-01

Regional cerebral blood flow was evaluated by single-photon emission CT (SPECT) with 123I-N-isopropyl-p-iodoamphetamine (123I-IMP) in 11 patients with dementia of the Alzheimer type, three patients with progressive dementia and motor neuron disease, and eight healthy control subjects. Regional blood flow measurements in the bilateral frontal, parietal association, and temporal cortices were lower in the Alzheimer dementia patients than in controls. Flow deficits in the parietal association cortex were demonstrated in all patients with Alzheimer-type dementia; these deficits were correlated with the severity of disease. Lateral hemispheric asymmetry was seen in nine of 11 patients with Alzheimer-type dementia. In all three patients with progressive dementia and motor neuron disease, flow deficits were demonstrated in the bilateral frontal and temporal cortices, but no flow deficits were seen in the parietal association cortex. Brain SPECT with 123I-IMP may be useful in the differential diagnosis and evaluation of the severity of degenerative dementia

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

DEFF Research Database (Denmark)

Skagen, K; Jensen, K; Henriksen, O

1982-01-01

1. The effect of head-up tilt upon subcutaneous blood flow in the distal arm and leg was studied in 12 patients with complete traumatic spinal cord transection at the cervical level. 2. Blood flow was measured by the local 133Xe washout technique. 3. Leg lowering induced a 47% decrease in blood f...

Heterogeneity of cerebral blood flow: a fractal approach

International Nuclear Information System (INIS)

Kuikka, J.T.; Hartikainen, P.

2000-01-01

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.) [de

Phase contrast MRI assessment of pedal blood flow

International Nuclear Information System (INIS)

Debatin, J.F.; Dalman, R.; Herfkens, R.J.; Harris, E.J.; Pelc, N.J.

1995-01-01

This study attempts to evaluate the reliability of cine phase contrast (PC) flow measurements in the assessment of normal pedal blood flow and quantitation of revascularisation-induced flow changes in patients with end-stage peripheral vascular occlusive disease (PVOD). Oblique axial cine-PC acquisitions were obtained on a 1.5 T MRI system at the level of the talotibial joints in 8 normal subjects on four separate occasions. Subsequently 8 patients with end-stage PVOD were examined before and after surgical revascularisation (bilateral, n = 2; unilateral, n = 6). Measured flow in the trifurcation vessels was highly variable among normal subjects. Total pedal flow ranged from 32 to 183 ml/min (mean 91 ml/min) and was significantly different between the subjects evaluated (P < 0.0001). Measurements in the same subject over time were considerably less variable (P < 0.005). Normal arterial flow patterns were consistently triphasic; those in patients with PVOD were either mono- or biphasic. Pedal flow measured by cine-PC in patients was reduced compared with normal subjects (mean 38.3 ml/min). Flow was slower in symptomatic limbs (26.7 ml/min) compared with asymptomatic ones (48.9 ml/min). Flow increases in revascularised limbs (mean 315%) were significantly different from those observed in non-affected limbs (P < 0.005). The ability to quantitate pedal blood flow and subsequent revascularisation-induced flow increases appears promising for the identification of optimal treatment options and monitoring of treatment results. (orig.)

Influence of cold water immersion on limb and cutaneous blood flow at rest.

Science.gov (United States)

Gregson, Warren; Black, Mark A; Jones, Helen; Milson, Jordon; Morton, James; Dawson, Brian; Atkinson, Greg; Green, Daniel J

2011-06-01

Cold water immersion reduces exercise-induced muscle damage. Benefits may partly arise from a decline in limb blood flow; however, no study has comprehensively investigated the influence of different degrees of cooling undertaken via cold water immersion on limb blood flow responses. To determine the influence of cold (8°C) and cool (22°C) water immersion on lower limb and cutaneous blood flow. Controlled laboratory study. Nine men were placed in a semireclined position and lowered into 8°C or 22°C water to the iliac crest for two 5-minute periods interspersed with 2 minutes of nonimmersion. Rectal and thigh skin temperature, deep and superficial muscle temperature, heart rate, mean arterial pressure, thigh cutaneous blood velocity (laser Doppler), and superficial femoral artery blood flow (duplex ultrasound) were measured during immersion and for 30 minutes after immersion. Indices of vascular conductance were calculated (flux and blood flow/mean arterial pressure). Reductions in rectal temperature (8°C, 0.2° ± 0.1°C; 22°C, 0.1° ± 0.1°C) and thigh skin temperature (8°C, 6.2° ± 0.5°C; 22°C, 3.2° ± 0.2°C) were greater in 8°C water than in 22°C (P water compared with 22°C (P = .01). These data suggest that immersion at both temperatures resulted in similar whole limb blood flow but, paradoxically, more blood was distributed to the skin in the colder water. This suggests that colder temperatures may be associated with reduced muscle blood flow, which could provide an explanation for the benefits of cold water immersion in alleviating exercise-induced muscle damage in sports and athletic contexts. Colder water temperatures may be more effective in the treatment of exercise-induced muscle damage and injury rehabilitation because of greater reductions in muscle blood flow.

Effect of age on cerebral blood flow during hypothermic cardiopulmonary bypass

International Nuclear Information System (INIS)

Brusino, F.G.; Reves, J.G.; Smith, L.R.; Prough, D.S.; Stump, D.A.; McIntyre, R.W.

1989-01-01

Cerebral blood flow was measured in 20 patients by xenon 133 clearance methodology during nonpulsatile hypothermic cardiopulmonary bypass to determine the effect of age on regional cerebral blood flow during these conditions. Measurements of cerebral blood flow at varying perfusion pressures were made in patients arbitrarily divided into two age groups at nearly identical nasopharyngeal temperature, hematocrit value, and carbon dioxide tension and with equal cardiopulmonary bypass flows of 1.6 L/min/m2. The range of mean arterial pressure was 30 to 110 mm Hg for group I (less than or equal to 50 years of age) and 20 to 90 mm Hg for group II (greater than or equal to 65 years of age). There was no significant difference (p = 0.32) between the mean arterial pressure in group I (54 +/- 28 mm Hg) and that in group II (43 +/- 21 mm Hg). The range of cerebral blood flow was 14.8 to 29.2 ml/100 gm/min for group I and 13.8 to 37.5 ml/100 gm/min for group II. There was no significant difference (p = 0.37) between the mean cerebral blood flow in group I (21.5 +/- 4.6 ml/100 gm/min) and group II (24.3 +/- 8.1 ml/100 gm/min). There was a poor correlation between mean arterial pressure and cerebral blood flow in both groups: group I, r = 0.16 (p = 0.67); group II, r = 0.5 (p = 0.12). In 12 patients, a second cerebral blood flow measurements was taken to determine the effect of mean arterial pressure on cerebral blood flow in the individual patient. Changes in mean arterial pressure did not correlate with changes in cerebral blood flow (p less than 0.90). We conclude that age does not alter cerebral blood flow and that cerebral blood flow autoregulation is preserved in elderly patients during nonpulsatile hypothermic cardiopulmonary bypass

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

DEFF Research Database (Denmark)

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

2010-01-01

The objective of this study was to quantify regional renal blood flow in humans. In nine young volunteers on a controlled diet, the lower abdomen was CT-scanned, and regional renal blood flow was determined by positron emission tomography (PET) scanning using H(2)(15)O as tracer. Measurements were......-NMMA injection to 1.57 ± 0.17 ml·g tissue(-1)·min(-1) (P blood flow was 4.67 ± 0.31 ml·g tissue(-1)·min(-1) during control, unchanged by glyceryl nitrate, and decreased after L-NMMA [3.48 ± 0.23 ml·(g·min)(-1), P renal medullary region in which...... the measured blood flow is 1) low, 2) independent of reduction in the VOI, and 3) reactive to changes in systemic NO supply. The technique seems to provide indices of renal medullary blood flow in humans....

Quantitative cerebral blood flow patterns with the short lived isotope 195m Au

International Nuclear Information System (INIS)

Lindner, P.; Nickel, O.

1984-01-01

A previously reported theory for quantitative cerebral blood flow measurements using intravenously injected nondiffusible radiotracers has been applied on patients after stroke and on volunteers undergoing a mental stimulation exercise. Quantitative measurements of cerebral blood flow patterns (in ml/min/100g) not only in p.a. but also in lateral views of the brain are possible by using of the short-lived (30 sec) isotope Au 195m. The energy spectrum of the eluate of the generator shows two strong photon peaks, one at 68 keV and a second at 262 keV. The 68 keV peak is suitable for perfusion studies in lateral views of the hemispheres, no 'look through' effect is seen. The 262 keV peak is good for studies in p.a. positions. The studies last less than 1 minute and can be repeated after 3 minutes. Parametric images for quantitative regional cerebral blood flow can be generated. The area of occluded vessels in the case of stroke can be made visible. Quantitative activation patterns of cerebral blood flow during mental stimulation can be generated. After optical stimulation a clear increase of blood flow was seen in the visual cortex. The results prove that not only with freely diffusible (like Xenon) but also with nondiffusible indicators like 195m Au it is possible to measure quantitatively cerebral blood flow patterns. Au 195m is very advantageous for quantitative clinical investigations of cerebrovascular disease. (Author)

Collateral blood flow in different cerebrovascular hierarchy provides endogenous protection in cerebral ischemia.

Science.gov (United States)

Luo, Chuanming; Liang, Fengyin; Ren, Huixia; Yao, Xiaoli; Liu, Qiang; Li, Mingyue; Qin, Dajiang; Yuan, Ti-Fei; Pei, Zhong; Su, Huanxing

2017-11-01

Collateral blood flow as vascular adaptions to focal cerebral ischemia is well recognized. However, few studies directly investigate the dynamics of collateral vessel recruitment in vivo and little is known about the effect of collateral blood flow in different cerebrovascular hierarchy on the neuropathology after focal ischemic stroke. Here, we report that collateral blood flow is critically involved in blood vessel compensations following regional ischemia. We occluded a pial arteriole using femtosecond laser ablating under the intact thinned skull and documented the changes of collateral flow around the surface communication network and between the surface communication network and subsurface microcirculation network using in vivo two photon microscopy imaging. Occlusion of the pial arteriole apparently increased the diameter and collateral blood flow of its leptomeningeal anastomoses, which significantly reduced the cortical infarction size. This result suggests that the collateral flow via surface communicating network connected with leptomeningeal anastomoses could greatly impact on the extent of infarction. We then further occluded the target pial arteriole and all of its leptomeningeal anastomoses. Notably, this type of occlusion led to reversals of blood flow in the penetrating arterioles mainly proximal to the occluded pial arteriole in a direction from the subsurface microcirculation network to surface arterioles. Interesting, the cell death in the area of ischemic penumbra was accelerated when we performed occlusion to cease the reversed blood flow in those penetrating arterioles, suggesting that the collateral blood flow from subsurface microcirculation network exerts protective roles in delaying cell death in the ischemic penumbra. In conclusion, we provide the first experimental evidence that collateral blood vessels at different cerebrovascular hierarchy are endogenously compensatory mechanisms in brain ischemia. © 2016 International Society of

[Assessment of maternal cerebral blood flow in patients with preeclampsia].

Science.gov (United States)

Mandić, Vesna; Miković, Zeljko; Dukić, Milan; Vasiljević, Mladenko; Filimonović, Dejan; Bogavac, Mirjana

2005-01-01

Systemic vasoconstriction 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 begining of eclamptic attack and 3) the application of anticonvulsive therapy. 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 ppreclampsia we found increased velocity values, Pi and Ri, especially in patients with signs of threatened eclampsia, suggesting that blood vessels changes are most prominent in severe preeclampsia. Cerebral blood flow meassurements can be used as a clinical test for the prediction of eclampsia. Magnesium-sulfate (MgSO4) has a signifficant role in prophylaxis and treatment of eclampsia, and, therefore, positive influence on reduction of cerebral ishemic lesions can be expected. We can conclude that changes of the cerebral blood flow can be evaluated by evaluating blood flow velocities in the medial cerebral artery. Velocities tend

Cerebral blood flow is reduced in patients with sepsis syndrome

International Nuclear Information System (INIS)

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

1989-01-01

The relationship between sepsis-induced CNS dysfunction and changes in brain blood flow remains unknown, and animal studies examining the influence of sepsis on cerebral blood flow (CBF) do not satisfactorily address that relationship. We measured CBF and cerebrovascular reactivity to CO 2 in nine patients with sepsis syndrome using the 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 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

Mechanisms of temporal variation in single-nephron blood flow in rats

DEFF Research Database (Denmark)

Yip, K P; Holstein-Rathlou, N H; Marsh, D J

1993-01-01

Modified laser-Doppler velocimetry was used to determine the number of different mechanisms regulating single-nephron blood flow. Two oscillations were identified in star vessel blood flow, one at 20-50 mHz and another at 100-200 mHz. Tubuloglomerular feedback (TGF) mediates the slower oscillation......, and the faster one is probably myogenic in origin. Acute hypertension increased autospectral power in the 20-50 mHz and 100-200 mHz frequency bands to 282 +/- 50 and 248 +/- 64%, respectively, of control even though mean single-nephron blood flow was autoregulated. Mean blood flow increased 24.6 +/- 6.1% when...... components in efferent arteriole blood flow....

Viscoelastic capillary flow: the case of whole blood

Directory of Open Access Journals (Sweden)

David Rabaud

2016-07-01

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.

Subcutaneous blood flow in man during sleep with continous epdural anaesthesia

DEFF Research Database (Denmark)

Sindrup, JH; Petersen, Lars Jelstrup; Kastrup, Jens

1996-01-01

BACKGROUND: Subcutaneous blood flow increases during sleep and we evaluated if this increase is affected by epidural anaesthesia. METHODS: Lower leg subcutaneous blood flow was determined by 133Xenon clearance in ten subjects during continous epidural anaesthesia at L2-L3 including eight hours...... of sleep, while the opper abdominal subcutaneous blood flow served as control. RESULTS: Epidural anaesthesia to the level of the umbilicus was followed by an increase in the lower leg subcutaneous blood flow fra 3.4 (1.8-6.3) to 7.8 (3.6-16.9) ml min-1 (median and range; P....4-7.6) ml min-1 100 g-1 after 88 (45-123) min. In contrast, until the period of sleep the upper abdominal region blood flow remained at 5.2 (3.2-6.4) ml min-1 100 g-1. During sleep, lower leg subcutaneous blood flow did not change significantly, but the upper abdominal flow increased to 6.2 (5.2-7.2) ml min...

Mathematical Modeling of Bingham Plastic Model of Blood Flow Through Stenotic Vessel

OpenAIRE

S.R. Verma

2014-01-01

The aim of the present paper is to study the axially symmetric, laminar, steady, one-dimensional flow of blood through narrow stenotic vessel. Blood is considered as Bingham plastic fluid. The analytical results such as pressure drop, resistance to flow and wall shear stress have been obtained. Effect of yield stress and shape of stenosis on resistance to flow and wall shear stress have been discussed through tables and graphically. It has been shown that resistance to flow and th...

Transplacental diffusion and blood flow of gravid bovine uterus

International Nuclear Information System (INIS)

Reynolds, L.P.; Ferrell, C.L.; Ford, S.P.

1985-01-01

Electromagnetic blood flow transducers and uterine arterial, uterine venous, umbilical venous, fetal femoral arterial, and fetal femoral venous catheters were implanted in 11 cows on day 161 +/- 4 of gestation. Antipyrine (0.66 M) plus NaCl (0.16 M) dissolved in deuterium oxide (D 2 O), or H 2 O, was infused at a constant rate into the fetal femoral vein catheter. Concentrations of antipyrine and D 2 O in uterine arterial and venous blood and antipyrine in fetal arterial and umbilical venous blood, as well as middle uterine arterial blood flow (electromagnetic transducer), were determined. Antipyrine and D 2 O gave similar estimates (steady-state diffusion method) of gravid uterine blood flow. In addition, the slope of the regression of D 2 O on antipyrine estimates was not different from one. Electromagnetic transducers gave estimates of uterine blood flow that were 32-42% of those obtained with steady-state diffusion but were correlated with estimates obtained by use of both antipyrine and D 2 O. The transplacental clearance rate of antipyrine was similar (per kg placenta) to that observed in ewes. It was suggested that the maternal and fetal microvasculatures of the bovine placenta could have a concurrent arrangement with vascular shunts or maldistribution of flows, as has been suggested for the ewe

[Prognostic Doppler ultrasound examination of fetal arteries blood flow].

Science.gov (United States)

Sieroszewski, Piotr; Sabatowska, Małgorzata; Karowicz-Bilińska, Agata; Suzin, Jacek

2002-08-01

Early detection of fetal risk is one of the main issues in today obstetrics. Ultrasound diagnostics plays a significant role, as the introduction of Doppler imaging method in the evaluation of blood flow has enabled non-invasive assessment of uteroplacental circulation. Therefore, we have analysed foetal three arteries: umbilical artery, middle cerebral artery and renal artery after determining the normal range for the analysed parameters. 1. Comparison of the obtained blood flow indices (S/D, RI, PI) in the umbilical artery, middle cerebral artery and renal artery of foetuses from normal and complicated full-term pregnancies. 2. Determination of indices: umbilical-cerebral and renal-cerebral in normal and pathological pregnancy. 3. Evaluation of feasibility of the analysed flow parameters for the detection of intrauterine foetal hypoxia. We have examined 151 women, who were divided into control group--101 pregnant women with normal pregnancy and study group--50 pregnant women with complicated pregnancy. All pregnant women underwent ultrasound examination using the Hitachi EUB 515 C (Japan) scanner with 3.5 MHz convex probe, connected to the colour pulsed Doppler. The study consisted of the biometric measurements and evaluation of the spectrum of blood flow in the umbilical artery, middle cerebral artery and renal artery. We have determined following indices: a) systolic-diastolic ratio S/D, resistance index RI, pulsatility index PI, b) umbilical-cerebral ratio P/M. (PI ua/PI mca), renal--cerebral ratio N/M (PI ra/PI mca). Statistically significant difference was found between the study and control groups for all the flow indices assessed (S/D, RI, PI) for the middle cerebral artery, for the indices P/M and N/M. (p < 0.001) and pulsatility index in the renal artery (p < 0.01). Similar, although slightly smaller difference (p < 0.05) was seen for the values of flow parameters in the umbilical artery. 1) Evaluation of blood flow in the middle cerebral artery, and in

Cerebral blood flow changes in cluster headache

International Nuclear Information System (INIS)

Norris, J.W.; Hachinski, V.C.; Cooper, P.W.

1976-01-01

Serial cerebral blood flod studies performed by the intra-carotid 133 Xenon method were fortuitously determined during the course of a cluster headache in a 32 year old man. The initial study was performed about 10 min after the headache began and showed values at the upper limit of normal. Twenty min after the headache started a second procedure showed that the autoregulatory response on hyperventilation was normal. Ergotamine tartrate was given intra-muscularly 23 min after the headache began and there was partial relief. A third cerebral blood flow estimation showed abnormally high values. The probable reasons for this are discussed. (author)

Effects of local single and fractionated X-ray doses on rat bone marrow blood flow and red blood cell volume

International Nuclear Information System (INIS)

Pitkaenen, M.A.; Hopewell, J.W.

1985-01-01

Time and dose dependent changes in blood flow and red blood cell volume were studied in the locally irradiated bone marrow of the rat femur after single and fractionated doses of X-rays. With the single dose of 10 Gy the bone marrow blood flow although initially reduced returned to the control levels by seven months after irradiation. With doses >=15 Gy the blood flow was still significantly reduced at seven months. The total dose levels predicted by the nominal standard dose equation for treatments in three, six or nine fractions produced approximately the same degree of reduction in the bone marrow blood flow seven months after the irradiation. However, the fall in the red blood cell volume was from 23 to 37% greater in the three fractions groups compared with that in the nine fractions groups. Using the red blood cell volume as a parameter the nominal standard dose formula underestimated the severity of radiation damage in rat bone marrow at seven months for irradiation with small numbers of large dose fractions. (orig.) [de

Electromagnetohydrodynamic flow of blood and heat transfer in a capillary with thermal radiation

International Nuclear Information System (INIS)

Sinha, A.; Shit, G.C.

2015-01-01

This paper presents a comprehensive theoretical study on heat transfer characteristics together with fully developed electromagnetohydrodynamic flow of blood through a capillary, having electrokinetic effects by considering the constant heat flux at the wall. The effect of thermal radiation and velocity slip condition have been taken into account. A rigorous mathematical model for describing Joule heating in electro-osmotic flow of blood including the Poisson–Boltzmann equation, the momentum equation and the energy equation is developed. The alterations in the thermal transport phenomenon, induced by the variation of imposed electromagnetic effects, are thoroughly explained through an elegant mathematical formalism. Results presented here pertain to the case where the height of the capillary is much greater than the thickness of electrical double layer comprising the stern and diffuse layers. The essential features of the electromagnetohydrodynamic flow of blood and associated heat transfer characteristics through capillary are clearly highlighted by the variations in the non-dimensional parameters for velocity profile, temperature profile and the Nusselt number. The study reveals that the temperature of blood can be controlled by regulating Joule heating parameter. - Highlights: • Electromagnetohydrodynamic flow of blood in capillary is studied. • Potential electric field is applied for driving elecroosmotic flow of blood. • Effect of thermal radiation, Joule heating and velocity slip is investigated. • Thermal radiation bears the significant change in the temperature field

Electromagnetohydrodynamic flow of blood and heat transfer in a capillary with thermal radiation

Energy Technology Data Exchange (ETDEWEB)

Sinha, A. [Department of Mathematics, Jadavpur University, Kolkata 700032 (India); Shit, G.C., E-mail: gopal_iitkgp@yahoo.co.in [Department of Mathematics, Jadavpur University, Kolkata 700032 (India); Institute of Mathematical Sciences, Chennai 600113 (India)

2015-03-15

This paper presents a comprehensive theoretical study on heat transfer characteristics together with fully developed electromagnetohydrodynamic flow of blood through a capillary, having electrokinetic effects by considering the constant heat flux at the wall. The effect of thermal radiation and velocity slip condition have been taken into account. A rigorous mathematical model for describing Joule heating in electro-osmotic flow of blood including the Poisson–Boltzmann equation, the momentum equation and the energy equation is developed. The alterations in the thermal transport phenomenon, induced by the variation of imposed electromagnetic effects, are thoroughly explained through an elegant mathematical formalism. Results presented here pertain to the case where the height of the capillary is much greater than the thickness of electrical double layer comprising the stern and diffuse layers. The essential features of the electromagnetohydrodynamic flow of blood and associated heat transfer characteristics through capillary are clearly highlighted by the variations in the non-dimensional parameters for velocity profile, temperature profile and the Nusselt number. The study reveals that the temperature of blood can be controlled by regulating Joule heating parameter. - Highlights: • Electromagnetohydrodynamic flow of blood in capillary is studied. • Potential electric field is applied for driving elecroosmotic flow of blood. • Effect of thermal radiation, Joule heating and velocity slip is investigated. • Thermal radiation bears the significant change in the temperature field.

Assessment of blood flow with (68)Ga-DOTA PET in experimental inflammation: a validation study using (15)O-water.

Science.gov (United States)

Autio, Anu; Saraste, Antti; Kudomi, Nobuyuki; Saanijoki, Tiina; Johansson, Jarkko; Liljenbäck, Heidi; Tarkia, Miikka; Oikonen, Vesa; Sipilä, Hannu T; Roivainen, Anne

2014-01-01

Increased blood flow and vascular permeability are key events in inflammation. Based on the fact that Gadolinium-1,4,7,10-tetraazacyclododecane-N,N',N'',N'''-tetraacetic acid (Gd-DOTA) is commonly used in magnetic resonance (MR) imaging of blood flow (perfusion), we evaluated the feasibility of its Gallium-68 labeled DOTA analog ((68)Ga-DOTA) for positron emission tomography (PET) imaging of blood flow in experimental inflammation. Adult, male Sprague-Dawley rats with turpentine oil induced sterile skin/muscle inflammation were anesthetized with isoflurane, and imaged under rest and adenosine-induced hyperemia by means of dynamic 2-min Oxygen-15 labeled water (H2 (15)O) and 30-min (68)Ga-DOTA PET. For the quantification of PET data, regions of interest (ROIs) were defined in the focus of inflammation, healthy muscle, myocardium and heart left ventricle. Radioactivity concentration in the ROIs versus time after injection was determined for both tracers and blood flow was calculated using image-derived input. According to the H2 (15)O PET, blood flow was 0.69 ± 0.15 ml/min/g for inflammation and 0.15 ± 0.03 ml/min/g for muscle during rest. The blood flow remained unchanged during adenosine-induced hyperemia 0.67 ± 0.11 and 0.12 ± 0.03 ml/min/g for inflammation and muscle, respectively, indicating that adenosine has little effect on blood flow in peripheral tissues in rats. High focal uptake of (68)Ga-DOTA was seen at the site of inflammation throughout the 30-min PET imaging. According to the (68)Ga-DOTA PET, blood flow measured as the blood-to-tissue transport rate (K1) was 0.60 ± 0.07 ml/min/g for inflammation and 0.14 ± 0.06 ml/min/g for muscle during rest and 0.63 ± 0.08 ml/min/g for inflammation and 0.09 ± 0.04 ml/min/g for muscle during adenosine-induced hyperemia. The H2 (15)O-based blood flow and (68)Ga-DOTA-based K1 values correlated well (r = 0.94, P DOTA PET imaging is useful for the quantification of increased blood flow induced by inflammation.

Assessment of blood flow with 68Ga-DOTA PET in experimental inflammation: a validation study using 15O-water

Science.gov (United States)

Autio, Anu; Saraste, Antti; Kudomi, Nobuyuki; Saanijoki, Tiina; Johansson, Jarkko; Liljenbäck, Heidi; Tarkia, Miikka; Oikonen, Vesa; Sipilä, Hannu T; Roivainen, Anne

2014-01-01

Increased blood flow and vascular permeability are key events in inflammation. Based on the fact that Gadolinium-1,4,7,10-tetraazacyclododecane-N,N‘,N‘‘,N‘‘‘-tetraacetic acid (Gd-DOTA) is commonly used in magnetic resonance (MR) imaging of blood flow (perfusion), we evaluated the feasibility of its Gallium-68 labeled DOTA analog (68Ga-DOTA) for positron emission tomography (PET) imaging of blood flow in experimental inflammation. Adult, male Sprague-Dawley rats with turpentine oil induced sterile skin/muscle inflammation were anesthetized with isoflurane, and imaged under rest and adenosine-induced hyperemia by means of dynamic 2-min Oxygen-15 labeled water (H2 15O) and 30-min 68Ga-DOTA PET. For the quantification of PET data, regions of interest (ROIs) were defined in the focus of inflammation, healthy muscle, myocardium and heart left ventricle. Radioactivity concentration in the ROIs versus time after injection was determined for both tracers and blood flow was calculated using image-derived input. According to the H2 15O PET, blood flow was 0.69 ± 0.15 ml/min/g for inflammation and 0.15 ± 0.03 ml/min/g for muscle during rest. The blood flow remained unchanged during adenosine-induced hyperemia 0.67 ± 0.11 and 0.12 ± 0.03 ml/min/g for inflammation and muscle, respectively, indicating that adenosine has little effect on blood flow in peripheral tissues in rats. High focal uptake of 68Ga-DOTA was seen at the site of inflammation throughout the 30-min PET imaging. According to the 68Ga-DOTA PET, blood flow measured as the blood-to-tissue transport rate (K1) was 0.60 ± 0.07 ml/min/g for inflammation and 0.14 ± 0.06 ml/min/g for muscle during rest and 0.63 ± 0.08 ml/min/g for inflammation and 0.09 ± 0.04 ml/min/g for muscle during adenosine-induced hyperemia. The H2 15O-based blood flow and 68Ga-DOTA-based K1 values correlated well (r = 0.94, P DOTA PET imaging is useful for the quantification of increased blood flow induced by inflammation. PMID

Central and peripheral blood flow during exercise with a continuous-flow left ventricular assist device: constant versus increasing pump speed: a pilot study

DEFF Research Database (Denmark)

Brassard, Patrice; Jensen, Annette S; Nordsborg, Nikolai

2011-01-01

with work rate would increase organ blood flow. Methods and Results- Invasively determined CO and leg blood flow and Doppler-determined cerebral perfusion were measured during 2 incremental cycle exercise tests on the same day in 8 patients provided with a HeartMate II LVAD. In random order, patients...

Quantitative blood flow analysis with digital techniques

International Nuclear Information System (INIS)

Forbes, G.

1984-01-01

The general principles of digital techniques in quantitating absolute blood flow during arteriography are described. Results are presented for a phantom constructed to correlate digitally calculated absolute flow with direct flow measurements. The clinical use of digital techniques in cerebrovascular angiography is briefly described. (U.K.)

Abnormal resting state corticolimbic blood flow in depressed unmedicated patients with major depression: a (15)O-H(2)O PET study.

Science.gov (United States)

Monkul, E Serap; Silva, Leandro A P; Narayana, Shalini; Peluso, Marco A M; Zamarripa, Frank; Nery, Fabiano G; Najt, Pablo; Li, John; Lancaster, Jack L; Fox, Peter T; Lafer, Beny; Soares, Jair C

2012-02-01

We investigated the differences in the resting state corticolimbic blood flow between 20 unmedicated depressed patients and 21 healthy comparisons. Resting state cerebral blood flow (CBF) was measured with H(2)(15)O PET. Anatomical MRI scans were performed on an Elscint 1.9 T Prestige system for PET-MRI coregistration. Significant changes in cerebral blood flow indicating neural activity were detected using an ROI-free image subtraction strategy. In addition, the resting blood flow in patients was correlated with the severity of depression as measured by HAM-D scores. Depressed patients showed decreases in blood flow in right anterior cingulate (Brodmann areas 24 and 32) and increased blood flow in left and right posterior cingulate (Brodmann areas 23, 29, 30), left parahippocampal gyrus (Brodmann area 36), and right caudate compared with healthy volunteers. The severity of depression was inversely correlated with the left middle and inferior frontal gyri (Brodmann areas 9 and 47) and right medial frontal gyrus (Brodmann area 10) and right anterior cingulate (Brodmann areas 24, 32) blood flow, and directly correlated with the right thalamus blood flow. These findings support previous reports of abnormalities in the resting state blood flow in the limbic-frontal structures in depressed patients compared to healthy volunteers. Copyright © 2011 Wiley Periodicals, Inc.

Supraorbital cutaneous blood flow rate during carotid endarterectomy

DEFF Research Database (Denmark)

Hove, Jens D; Rosenberg, Iben; Sejrsen, Per

2006-01-01

: The supraorbital cutaneous blood flow rate was measured by the application of heat to the skin and following the subsequent dissipation of the heat in seven patients undergoing carotid endarterectomy. At the same time, the oxygenation in the right and left frontal region was monitored by near-infrared spectroscopy......BACKGROUND: The supraorbital skin region is supplied by the supraorbital artery, which is a branch of the internal carotid artery. The supraorbital cutaneous blood flow rate may therefore be influenced by changes in the internal carotid artery flow during carotid endarterectomy. METHODS...... (NIRS). RESULTS: During cross-clamping of the carotid artery, the ipsilateral NIRS-determined frontal oxygenation tended to decrease [67 +/- 13% to 61 +/- 11% (P = 0.06); contralateral 68 +/- 11% to 66 +/- 8%] as did the supraorbital cutaneous blood flow rate from 56 +/- 23 to 44 +/- 7 ml 100 g(-1) min...

Regional cerebral blood flow in childhood headache

International Nuclear Information System (INIS)

Roach, E.S.; Stump, D.A.

1989-01-01

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

FDG metabolism and uptake versus blood flow in women with untreated primary breast cancers

International Nuclear Information System (INIS)

Zasadny, Kenneth R.; Tatsumi, Mitsuaki; Wahl, Richard L.

2003-01-01

The aim of this study was to determine the relationship between tumor blood flow and glucose utilization in women with untreated primary breast carcinomas. Noninvasive determinations of blood flow and glucose utilization with positron emission tomography (PET) were performed in 101 regions of tumor from nine women with untreated primary breast carcinoma. [ 15 O]H 2 O PET scans of tumor blood flow were compared with fluorine-18 fluoro-2-deoxy-D-glucose (FDG) PET scans of tumor glucose metabolism. Modeling of multiple parameters was undertaken and flow and glucose utilization compared. Mean whole-tumor blood flow was 14.9 ml dl -1 min -1 , but ranged from 7.6 to 29.2 ml dl -1 min -1 . Mean whole-tumor standardized uptake value corrected for lean body mass, SUV-lean (50-60 min), was 2.32±0.19 while mean K i was 1.2 ml dl -1 min -1 for FDG. SUV-lean and blood flow were strongly correlated (r=0.82, P=0.007) as were K 1 for FDG and flow (r=0.84, P=0.004). In these women with untreated breast cancers, FDG uptake (SUV-lean) and tumor blood flow are strongly correlated. The slope of FDG uptake versus blood flow appears higher at low flow rates, suggesting the possible presence of areas of tumor hypoxia. (orig.)

Hydrogen clearance: Assessment of technique for measurement of skin-flap blood flow in pigs

International Nuclear Information System (INIS)

Thomson, J.G.; Kerrigan, C.L.

1991-01-01

The hydrogen clearance technique has been used for many years by investigators to determine brain blood flow and has been partially validated in this setting using other methods of blood flow measurement. The method has been modified to allow blood flow measurements in skin, but the accuracy of H2 clearance for measuring skin blood flow has not been determined. Multiple blood flow measurements were performed using H2 clearance and radioactive microspheres on skin flaps and control skin in pigs. On 12 pigs, a total of 117 flap and 42 control skin measurements were available for analysis. There was no significant difference between the two techniques in measuring mean control skin blood flow. In skin flaps, H2 clearance was significantly correlated to microsphere-measured blood flow, but it consistently gave an overestimate. Sources of error may include injury to the tissues by insertion of electrodes, consumption of H2 by the electrodes, or diffusion of H2 from the relatively ischemic flap to its well-vascularized bed. Further studies are necessary to determine the cause of this error and to measure the technique's accuracy in skeletal muscle and other flaps

Subcutaneous blood flow during insulin-induced hypoglycaemia: studies in juvenile diabetics with and without autonomic neuropathy and in normal subjects

Energy Technology Data Exchange (ETDEWEB)

Hilsted, J; Madsbad, S; Sestoft, L

1982-08-01

Subcutaneous blood flow was measured preceding insulin-induced hypoglycaemia, at the onset of hypoglycaemic symptoms and 2 h later in juvenile diabetics with and without autonomic neuropathy and in normal males. In all groups subcutaneous blood flow decreased at the onset of hypoglycaemic symptoms compared with pre-hypoglycaemic flow. Two hours after onset of hypoglycaemic symptoms, subcutaneous blood flow was still significantly decreased compared with pre-hypoglycaemic flow. In normal subjects local nerve blockade had no effect on blood flow changes during hypoglycaemia, whereas local alpha-receptor blockade abolished the vasoconstrictor response. We suggest that circulating catecholamines stimulating vascular alpha-receptors are probably responsible for flow reduction in the subcutaneous tissue during hypoglycaemia.

Effect of flow rate and temperature on transmembrane blood pressure drop in an extracorporeal artificial lung.

Science.gov (United States)

Park, M; Costa, E L V; Maciel, A T; Barbosa, E V S; Hirota, A S; Schettino, G de P; Azevedo, L C P

2014-11-01

Transmembrane pressure drop reflects the resistance of an artificial lung system to blood transit. Decreased resistance (low transmembrane pressure drop) enhances blood flow through the oxygenator, thereby, enhancing gas exchange efficiency. This study is part of a previous one where we observed the behaviour and the modulation of blood pressure drop during the passage of blood through artificial lung membranes. Before and after the induction of multi-organ dysfunction, the animals were instrumented and analysed for venous-venous extracorporeal membrane oxygenation, using a pre-defined sequence of blood flows. Blood flow and revolutions per minute (RPM) of the centrifugal pump varied in a linear fashion. At a blood flow of 5.5 L/min, pre- and post-pump blood pressures reached -120 and 450 mmHg, respectively. Transmembrane pressures showed a significant spread, particularly at blood flows above 2 L/min; over the entire range of blood flow rates, there was a positive association of pressure drop with blood flow (0.005 mmHg/mL/minute of blood flow) and a negative association of pressure drop with temperature (-4.828 mmHg/(°Celsius). These associations were similar when blood flows of below and above 2000 mL/minute were examined. During its passage through the extracorporeal system, blood is exposed to pressure variations from -120 to 450 mmHg. At high blood flows (above 2 L/min), the drop in transmembrane pressure becomes unpredictable and highly variable. Over the entire range of blood flows investigated (0-5500 mL/min), the drop in transmembrane pressure was positively associated with blood flow and negatively associated with body temperature. © The Author(s) 2014.

Cerebral blood flow and oximetry response to blood transfusion in relation to chronological age in preterm infants.

Science.gov (United States)

Banerjee, J; Leung, T S; Aladangady, N

2016-06-01

Preterm infants frequently receive blood transfusion (BT) and the aim of this study was to measure the effect of BT on cerebral blood flow and oxygenation in preterm infants in relation to chronological age. Preterm infants undergoing intensive care recruited to three chronological age groups: 1 to 7 (Group 1; n=20), 8 to 28 (Group 2; n=21) & ≥29days of life (Group 3; n=18). Pre and post-BT anterior cerebral artery (ACA) time averaged mean velocity (TAMV) and superior vena cava (SVC) flow were measured. Cerebral Tissue Haemoglobin Index (cTHI) and Oxygenation Index (cTOI) were measured from 15-20min before to 15-20min post-BT using NIRS. Vital parameters and blood pressure were measured continuously. Mean BP increased significantly, and there was no significant change in vital parameters following BT. Pre-BT ACA TAMV was higher in Group 2 and 3 compared to Group 1 (pBlood transfusion increased cTOI and cTHI and decreased ACA TAMV in all groups. PDA had no impact on the baseline cerebral oximetry and blood flow as well as changes following blood transfusion. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Correlation of volumetric flow rate and skin blood flow with cold intolerance in digital replantation.

Science.gov (United States)

Zhao, Gang; Mi, Jingyi; Rui, Yongjun; Pan, Xiaoyun; Yao, Qun; Qiu, Yang

2017-12-01

Cold intolerance is a common complication of digital replantation. The exact etiology is unclear, but it is considered to be multifactorial, including nonsurgical characteristics, vascular, and neurologic conditions. Blood flow may play a significant role in cold intolerance. This study was designed to evaluate the correlation of digital blood flow, including volumetric flow rate (VFR) and skin blood flow (SkBF), with cold intolerance in replanted fingers.A retrospective study was conducted among patients who underwent digital replantation between 2010 and 2013. Patients were selected into study cohort based on the inclusion criteria. Surgical data was collected on each patient, including age, sex, injury mechanism, amputation level, ischemia time, number of arteries repaired, and whether or not vascular crisis occurred. Patients were included as study cohort with both nerves repaired and without chronic disease. Cold intolerance was defined as a Cold Intolerance Symptom Severity (CISS) score over 30. The arterial flow velocity and caliber were measured by Color Doppler Ultrasound and the digital VFR was calculated. The SkBF was measured by Laser Speckle Imager. Both VFR and SkBF were calculated as a percentage of the contralateral fingers. Comparative study of surgical data and blood flow was performed between the patient with and without cold intolerance. Correlation between VFR and SkBF was also analyzed.A total of 93 patients met inclusion criteria for the study. Approximately, 42 patients were identified as having cold intolerance. Fingers that survived vascular crisis had a higher incidence of cold intolerance with a lower VFR and SkBF. The VFR was higher in 2-artery replantation, but the SkBF and incidence of cold intolerance did not differ significantly. No differences were found in age, sex, injury mechanism, amputation level, or ischemia time. Furthermore, no correlation was found between VFR and SkBF.Cold intolerance of digital replantation is associated

Reduced blood flow to contracting skeletal muscle in ageing humans

DEFF Research Database (Denmark)

Nyberg, Michael Permin; Hellsten, Ylva

2016-01-01

The ability to sustain a given absolute submaximal workload declines with advancing age likely due to a lower level of blood flow and O2 delivery to the exercising muscles. Given that physical inactivity mimics many of the physiological changes associated with ageing, separating the physiological...... 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...... the O2 demand of the active skeletal muscle of aged individuals during conditions where systemic blood flow is not limited by cardiac output seems to a large extent to be related to the level of physical activity. This article is protected by copyright. All rights reserved....

Renal sympathetic nerve, blood flow, and epithelial transport responses to thermal stress.

Science.gov (United States)

Wilson, Thad E

2017-05-01

Thermal stress is a profound sympathetic stress in humans; kidney responses involve altered renal sympathetic nerve activity (RSNA), renal blood flow, and renal epithelial transport. During mild cold stress, RSNA spectral power but not total activity is altered, renal blood flow is maintained or decreased, and epithelial transport is altered consistent with a sympathetic stress coupled with central volume loaded state. Hypothermia decreases RSNA, renal blood flow, and epithelial transport. During mild heat stress, RSNA is increased, renal blood flow is decreased, and epithelial transport is increased consistent with a sympathetic stress coupled with a central volume unloaded state. Hyperthermia extends these directional changes, until heat illness results. Because kidney responses are very difficult to study in humans in vivo, this review describes and qualitatively evaluates an in vivo human skin model of sympathetically regulated epithelial tissue compared to that of the nephron. This model utilizes skin responses to thermal stress, involving 1) increased skin sympathetic nerve activity (SSNA), decreased skin blood flow, and suppressed eccrine epithelial transport during cold stress; and 2) increased SSNA, skin blood flow, and eccrine epithelial transport during heat stress. This model appears to mimic aspects of the renal responses. Investigations of skin responses, which parallel certain renal responses, may aid understanding of epithelial-sympathetic nervous system interactions during cold and heat stress. Copyright © 2016 Elsevier B.V. All rights reserved.

[Regional blood flow and bone uptake of methylene-diphosphonate-technetium-99m].

Science.gov (United States)

Vattimo, A; Martini, G; Pisani, M

1983-05-30

Sudeck's atrophy of the foot is an acute, patchy osteoporosis that, on bone scan, shows an increase in both bone blood flow and local bone uptake of bone-seeking radionuclides. The purpose of this study was to evaluate the relationship between bone uptake of 99mTc-MDP and local bone blood flow. In some patients with Sudeck's atrophy of one foot we measured local bone blood flow and bone uptake of 99mTc-MDP. External counting of radioactivity, with a count-rate of 1 second was performed for 60 minutes after i.v. injection of a known dose of 99mTc-MDP in some patients with Sudeck's atrophy of the foot. The regions of interest (ROI) were selected on the basis of a bone scan performed 24 hours earlier. We assumed that the data recorded during the first seconds (7-10) reflect local blood flow and the data at 60 minutes reflect the bone uptake. The ratio between the local blood flow in the involved and healthy foot was higher than the local bone uptake ratio. The ratio between bone uptake and local bone blood flow was higher in the normal foot than in the affected one. These results suggest that the bone avidity for bone-seeking radionuclides is lower in Sudeck's atrophy than in normal bone.

Skin blood flow from gas transport: helium xenon and laser Doppler compared

Energy Technology Data Exchange (ETDEWEB)

Neufeld, G.R.; Galante, S.R.; Whang, J.M.; DeVries, D.; Baumgardner, J.E.; Graves, D.J.; Quinn, J.A.

1988-03-01

A study was designed to compare three independent measures of cutaneous blood flow in normal healthy volunteers: xenon-133 washout, helium flux, and laser velocimetry. All measurements were confined to the volar aspect of the forearm. In a large group of subjects we found that helium flux through intact skin changes nonlinearly with the controlled local skin temperature whereas helium flux through stripped skin, which is directly proportional to skin blood flow, changes linearly with cutaneous temperature over the range 33 degrees to 42 degrees. In a second group of six volunteers we compared helium flux through stripped skin to xenon-133 washout (intact skin) at a skin temperature of 33 degrees, and we found an essentially linear relationship between helium flux and xenon measured blood flow. In a third group of subjects we compared helium flux blood flow (stripped skin) to laser doppler velocimetric (LDV) measurements (intact skin) at adjacent skin sites and found a nonlinear increase in the LDV skin blood flow compared to that determined by helium over the same temperature range. A possible explanation for the nonlinear increases of helium flux through intact skin and of LDV output with increasing local skin temperature is that they reflect more than a change in blood flow. They may also reflect physical changes in the stratum corneum, which alters its diffusional resistance to gas flux and its optical characteristics.

Skin blood flow from gas transport: helium xenon and laser Doppler compared

International Nuclear Information System (INIS)

Neufeld, G.R.; Galante, S.R.; Whang, J.M.; DeVries, D.; Baumgardner, J.E.; Graves, D.J.; Quinn, J.A.

1988-01-01

A study was designed to compare three independent measures of cutaneous blood flow in normal healthy volunteers: xenon-133 washout, helium flux, and laser velocimetry. All measurements were confined to the volar aspect of the forearm. In a large group of subjects we found that helium flux through intact skin changes nonlinearly with the controlled local skin temperature whereas helium flux through stripped skin, which is directly proportional to skin blood flow, changes linearly with cutaneous temperature over the range 33 degrees to 42 degrees. In a second group of six volunteers we compared helium flux through stripped skin to xenon-133 washout (intact skin) at a skin temperature of 33 degrees, and we found an essentially linear relationship between helium flux and xenon measured blood flow. In a third group of subjects we compared helium flux blood flow (stripped skin) to laser doppler velocimetric (LDV) measurements (intact skin) at adjacent skin sites and found a nonlinear increase in the LDV skin blood flow compared to that determined by helium over the same temperature range. A possible explanation for the nonlinear increases of helium flux through intact skin and of LDV output with increasing local skin temperature is that they reflect more than a change in blood flow. They may also reflect physical changes in the stratum corneum, which alters its diffusional resistance to gas flux and its optical characteristics

Investigation of spiral blood flow in a model of arterial stenosis.

Science.gov (United States)

Paul, Manosh C; Larman, Arkaitz

2009-11-01

The spiral component of blood flow has both beneficial and detrimental effects in human circulatory system [Stonebridge PA, Brophy CM. Spiral laminar flow in arteries? Lancet 1991; 338: 1360-1]. We investigate the effects of the spiral blood flow in a model of three-dimensional arterial stenosis with a 75% cross-sectional area reduction at the centre by means of computational fluid dynamics (CFD) techniques. The standard k-omega model is employed for simulation of the blood flow for the Reynolds number of 500 and 1000. We find that for Re=500 the spiral component of the blood flow increases both the total pressure and velocity of the blood, and some significant differences are found between the wall shear stresses of the spiral and non-spiral induced flow downstream of the stenosis. The turbulent kinetic energy is reduced by the spiral flow as it induces the rotational stabilities in the forward flow. For Re=1000 the tangential component of the blood velocity is most influenced by the spiral speed, but the effect of the spiral flow on the centreline turbulent kinetic energy and shear stress is mild. The results of the effects of the spiral flow are discussed in the paper along with the relevant pathological issues.

Unsteady Blood Flow with Nanoparticles Through Stenosed Arteries in the Presence of Periodic Body Acceleration

Science.gov (United States)

Fatin Jamil, Dzuliana; Roslan, Rozaini; Abdulhameed, Mohammed; Che-Him, Norziha; Sufahani, Suliadi; Mohamad, Mahathir; Ghazali Kamardan, Muhamad

2018-04-01

The effects of nanoparticles such as Fe 3O4,TiO2, and Cu on blood flow inside a stenosed artery are studied. In this study, blood was modelled as non-Newtonian Bingham plastic fluid subjected to periodic body acceleration and slip velocity. The flow governing equations were solved analytically by using the perturbation method. By using the numerical approaches, the physiological parameters were analyzed, and the blood flow velocity distributions were generated graphically and discussed. From the flow results, the flow speed increases as slip velocity increases and decreases as the values of yield stress increases.

Recovery of testicular blood flow following ligation of testicular vessels

International Nuclear Information System (INIS)

Pascual, J.A.; Villanueva-Meyer, J.; Salido, E.; Ehrlich, R.M.; Mena, I.; Rajfer, J.

1989-01-01

To determine whether initial ligation of the testicular vessels of the high undescended testis followed by a delayed secondary orchiopexy is a viable alternative to the classical Fowler-Stephens procedure, a series of preliminary experiments were conducted in the rat in which testicular blood flow was measured by the 133-xenon washout technique before, and 1 hour and 30 days after ligation of the vessels. In addition, testicular histology, and testis and sex-accessory tissue weights were measured in 6 control, 6 sham operated and 6 testicular vessel ligated rats 54 days after vessel ligation. The data demonstrate that ligation and division of the testicular blood vessels produce an 80 per cent decrease in testicular blood flow 1 hour after ligation of the vessels. However, 30 days later testis blood flow returns to the control and pre-treatment value. There were no significant changes in testis or sex-accessory tissue weights 54 days after vessel ligation. Histologically, 4 of the surgically operated testes demonstrated necrosis of less than 25 per cent of the seminiferous tubules while 1 testis demonstrated more than 75 per cent necrosis. The rest of the tubules in all 6 testes demonstrated normal spermatogenesis. From this study we conclude that initial testicular vessel ligation produces an immediate decrease in testicular blood flow but with time the collateral vessels are able to compensate and return the testis blood flow to its normal pre-treatment value. These preliminary observations lend support for the concept that initial ligation of the testicular vessels followed by a delayed secondary orchiopexy in patients with a high undescended testis may be a possible alternative to the classical Fowler-Stephens approach

Computational Fluid Dynamics Analysis of Pulsatile Blood Flow Behavior in Modelled Stenosed Vessels with Different Severities

Directory of Open Access Journals (Sweden)

Mohsen Mehrabi

2012-01-01

Full Text Available This study focuses on the behavior of blood flow in the stenosed vessels. Blood is modelled as an incompressible non-Newtonian fluid which is based on the power law viscosity model. A numerical technique based on the finite difference method is developed to simulate the blood flow taking into account the transient periodic behaviour of the blood flow in cardiac cycles. Also, pulsatile blood flow in the stenosed vessel is based on the Womersley model, and fluid flow in the lumen region is governed by the continuity equation and the Navier-Stokes equations. In this study, the stenosis shape is cosine by using Tu and Devil model. Comparing the results obtained from three stenosed vessels with 30%, 50%, and 75% area severity, we find that higher percent-area severity of stenosis leads to higher extrapressure jumps and higher blood speeds around the stenosis site. Also, we observe that the size of the stenosis in stenosed vessels does influence the blood flow. A little change on the cross-sectional value makes vast change on the blood flow rate. This simulation helps the people working in the field of physiological fluid dynamics as well as the medical practitioners.

Spatial Temporal Image Correlation Spectroscopy (STICS) for Flow Analysis with Application for Blood Flow Mapping (abstract)

Science.gov (United States)

Rossow, Molly; Mantulin, William M.; Gratton, Enrico

2009-04-01

It is important for surgeons to be able to measure blood flow in exposed arterioles during surgery. We report our progress in the development of an optical technique that will measure blood flow in surgically exposed blood vessels and enable previously difficult measurements. By monitoring optical fluctuations, the optical technique, based on Spatial Temporal Image Correlation (STICS), will directly measure the velocity of micron-scale particles-such as red blood cells. It will complement existing technology and provide qualitative measurements that were not previously possible. It relies on the concept that blood, when viewed on a small enough scale, is an inhomogeneous substance. Individual blood cells passing between a near-infrared light source and a detector will cause fluctuations in the transmitted optical signal. The speed, direction, and flow pattern of blood cells can be determined from these optical fluctuations. We present a series of computer simulations and experiments on phantom and animal systems to test this technique's ability to map complex flow patterns.

Single-photon tomographic determination of regional cerebral blood flow in epilepsy

International Nuclear Information System (INIS)

Bonte, F.J.; Devous, M.D. Sr.; Stokely, E.M.; Homan, R.W.

1983-01-01

Using a single-photon emission computed tomographic scanner (SPECT) the authors determined regional cerebral blood flow (rCBF) with inhaled xenon-133, a noninvasive procedure. Studies were performed in 40 normal individuals, and these were compared with rCBF determinations in 51 patients with seizure disorders. Although positive results were obtained in 15 of 16 patients with mass lesions, the group of principal interest comprised 25 patients suffering from ''temporal lobe'' epilepsy. Only one of these had a positive x-ray computed tomogram, but 16 had positive findings on rCBF study. These findings included increased local blood flow in the ictal state and reduced flow interictally

Relationship between insulin resistance and tissue blood flow in preeclampsia.

Science.gov (United States)

Anim-Nyame, Nick; Gamble, John; Sooranna, Suren R; Johnson, Mark R; Steer, Philip J

2015-05-01

Preeclampsia is characterized by generalized endothelial dysfunction and impaired maternal tissue perfusion, and insulin resistance is a prominent feature of this disease. The aim of this study was to test the hypothesis that insulin resistance in preeclampsia is related to the reduced resting tissue blood flow. We used venous occlusion plethysmography to compare the resting calf muscle blood flow (measured as QaU) in 20 nulliparous women with preeclampsia and 20 normal pregnant controls matched for maternal age, gestational age, parity and BMI during the third trimester. Fasting blood samples were obtained to measure the plasma concentrations of insulin and glucose, and to calculate the fasting insulin resistance index (FIRI), a measure of insulin resistance in both groups of women. Calf blood flow was significantly reduced in the preeclampsia group (1.93 ± 0.86 QaU), compared with normal pregnant controls (3.94 ± 1.1 QaU, P insulin concentrations and Insulin Resistance Index were significantly higher in preeclampsia compared with normal pregnancy (P insulin concentrations (r = -0.57, P = 0.008) and FIRI (r = -0.59, P = 0.006) in preeclampsia, but not in normal pregnancy. These findings support our hypothesis and raise the possibility that reduced tissue blood flow may a play a role in the increased insulin resistance seen in preeclampsia.

Determination of hepatic blood flow through radioactive colloidal gold in congestive heart foilure

International Nuclear Information System (INIS)

Papaleo Netto, M.; Carvalho, N.; Carvalho Filho, E.T.; Forti, N.A.; Giannini, S.D.; Diament, J.; Decourt, L.V.; Chiaverini, R.

1974-01-01

Hepatic blood flow as derermined by radioactive colloidal gold and its correlation with total blood valume are studied in 13 patients with predominantly right-side congestive heart failure. During the phase of cardiac compensation, the following events occur: 1) significant decrease of the half-life of the clearance of radioactive colloidal gold and of the total blood volume; 2) increase of the clearance constant of the radioactive substance and of hepatic blood flow; 3) significantion correlation between the clearance constant and the total blood volume [pt

Placental blood flow measurements with radioisotopes in the pregnant guinea pig

International Nuclear Information System (INIS)

Schmitt, R.; Giese, W.; Kurz, C.S.; Kuenzel, W.

1976-01-01

In 15 pregnant guinea pigs near term the blood flow (BF) of the myometrium and the placenta as well as the cardiac output were measured with 99 Tcsup(m)-labelled microspheres. In front of one placenta the clearance of 133 Xe was estimated in the same animal. For the 133 Xe measurement a theoretical concept is presented. The mean placental BF is 105ml/(minx100g)(SD:84) for 99 Tcsup(m) and 244(SD:80)ml/(minx100g) for 133 Xe. The difference in both flow values is assumed to be related to foetal placental BF. The placental blood flow is also related to the location of the placenta in the uterine horn. The ratio of myometrial blood flow to placental blood flow decreased with an increase in the mean arterial blood pressure. The measurements are a preliminary report of an attempt to compare two different methods in measuring placental blood flow. (author)

Skin cooling on contact with cold materials: the effect of blood flow during short-term exposures.

Science.gov (United States)

Jay, Ollie; Havenith, George

2004-03-01

This study investigates the effect of blood flow upon the short-term (cooling response in order to ascertain whether sufferers of circulatory disorders, such as the vasospastic disorder Raynaud's disease, are at a greater risk of cold injury than people with a normal rate of blood flow. Eight female volunteers participated, touching blocks of stainless steel and nylon with a finger contact force of 2.9 N at a surface temperature of -5 degrees C under occluded and vasodilated conditions. Contact temperature (Tc) of the finger pad was measured over time using a T-type thermocouple. Forearm blood flow was measured using strain gauge plethysmography. Contact cooling responses were analysed by fitting a modified Newtonian cooling curve. A significant difference was found between the starting skin temperatures for the two blood flow conditions (Peffect of blood flow was found upon any of the derived cooling curve parameters characterizing the skin cooling response (P>0.05). It is hypothesized that the finger contact force used (2.9 N) and the resultant pressure upon the tissue of the contact finger pad restricted the blood supply to the contact area under both blood flow conditions; therefore, no effect of blood flow was found upon the parameters describing the contact cooling response. Whilst the findings of this study are sufficient to draw a conclusion for those in a working environment, i.e. contact forces below 2.9 N will seldom be encountered, a further study will be required to ascertain conclusively whether blood flow does affect the contact cooling response at a finger contact force low enough to allow unrestricted blood flow to the finger pad. Further protocol improvements are also recommended.

Effects of anesthesia on the cerebral capillary blood flow in young and old mice

Science.gov (United States)

Moeini, Mohammad; Tabatabaei, Maryam S.; Bélanger, Samuel; Avti, Pramod; Castonguay, Alexandre; Pouliot, Philippe; Lesage, Frédéric

2015-03-01

Despite recent findings on the possible role of age-related cerebral microvasculature changes in cognition decline, previous studies of capillary blood flow in aging (using animal models) are scarce and limited to anesthetized conditions. Since anesthesia can have different effects in young and old animals, it may introduce a confounding effect in aging studies. The present study aimed to eliminate the potential confound introduced by anesthesia by measuring capillary blood flow parameters in both awake conditions and under isoflurane anesthesia. We used 2-photon laser scanning fluorescence microscopy to measure capillary diameter, red blood cell velocity and flux, hematocrit and capillary volumetric flow in individual capillaries in the barrel cortex of 6- and 24-month old C57Bl/6 mice. It was observed that microvascular properties are significantly affected by anesthesia leading to different trends in capillary blood flow parameters with aging when measured under awake or anesthetized conditions. The findings in this study suggest taking extra care in interpreting aging studies from anesthetized animals.

Capillary pericytes regulate cerebral blood flow in health and disease

DEFF Research Database (Denmark)

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

2014-01-01

Increases in brain blood flow, evoked by neuronal activity, power neural computation and form the basis of BOLD (blood-oxygen-level-dependent) functional imaging. Whether blood flow is controlled solely by arteriole smooth muscle, or also by capillary pericytes, is controversial. We demonstrate t...

Hybrid PIV-PTV technique for measuring blood flow in rat mesenteric vessels.

Science.gov (United States)

Ha, Hojin; Nam, Kweon-Ho; Lee, Sang Joon

2012-11-01

The micro-particle tracking velocimetry (μ-PTV) technique is used to obtain the velocity fields of blood flow in the microvasculature under in vivo conditions because it can provide the blood velocity distribution in microvessels with high spatial resolution. The in vivo μ-PTV technique usually requires a few to tens of seconds to obtain a whole velocity profile across the vessel diameter because of the limited number density of tracer particles under in vivo conditions. Thus, the μ-PTV technique alone is limited in measuring unsteady blood flows that fluctuate irregularly due to the heart beating and muscle movement in surrounding tissues. In this study, a new hybrid PIV-PTV technique was established by combining PTV and particle image velocimetry (PIV) techniques to resolve the drawbacks of the μ-PTV method in measuring blood flow in microvessels under in vivo conditions. Images of red blood cells (RBCs) and fluorescent particles in rat mesenteric vessels were obtained simultaneously. Temporal variations of the centerline blood velocity were monitored using a fast Fourier transform-based cross-correlation PIV method. The fluorescence particle images were analyzed using the μ-PTV technique to extract the spatial distribution of the velocity vectors. Data from the μ-PTV and PIV methods were combined to obtain a better estimate of the velocity profile in actual blood flow. This technique will be useful in investigating hemodynamics in microcirculation by measuring unsteady irregular blood flows more accurately. Copyright © 2012 Elsevier Inc. All rights reserved.

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

International Nuclear Information System (INIS)

Ikemura, Tsukasa; Kashima, Hideaki; Yamaguchi, Yuji; Miyaji, Akane; Hayashi, Naoyuki

2015-01-01

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

Modeling cerebral blood flow during posture change from sitting to standing

DEFF Research Database (Denmark)

Ottesen, Johnny T.; Olufsen, M.; Tran, H.T.

2004-01-01

extremities, the brain, and the heart. We use physiologically based control mechanisms to describe the regulation of cerebral blood flow velocity and arterial pressure in response to orthostatic hypotension resulting from postural change. To justify the fidelity of our mathematical model and control......Abstract Hypertension, decreased cerebral blood flow, and diminished cerebral blood flow velocity regulation, are among the first signs indicating the presence of cerebral vascular disease. In this paper, we will present a mathematical model that can predict blood flow and pressure during posture...