Blood vessels have been shown to play perfusion-independent roles in organogenesis. Here, we examined whether blood vessels determine branching stereotypy of the mouse lung airways in which coordinated branching of epithelial and vascular tubes culminates in their co-alignment. Using different ablative strategies to eliminate the lung vasculature, both in vivo ...

Background Dendritic cells (DCs) are crucial for the processing of antigens, T lymphocyte priming and the development of asthma and allergy. Smokers with asthma display altered therapeutic behaviour and a reduction in endobronchial DC CD83 expression compared with non-smokers with asthma. No information is available on the impact of smoking ...

INTRODUCTION: Maximum expiratory flow is a useful measurement of lung mechanics because of its reproducibility, ease of measurement, and sensitivity to changes in lung mechanical properties. Expiratory isovolume pressure - flow (IVPF) curves allow determination of both flow limitation and airway resistance and effect of disease or treatment on these. ...

The regional distribution of inhaled gas within the lung is affected in part by normal variations in airway geometry or by obstructions resulting from disease. In the present work, the effects of heterogeneous airway obstructions on the distribution of air and helium-oxygen were examined using an in vitro model, the ...

Penh is a dimensionless index normally used to evaluate changes in the shape of the airflow pattern entering and leaving a whole-body flow plethysmograph as an animal breathes. The index is sensitive to changes in the distribution of area under the waveform during exhalation and increases in a nonlinear fashion ...

A dipolar flow structure is experimentally studied in a layer of salt solution driven by time-independent electromagnetic forcing. In particular, the response of the flow to the forcing is quantified by measuring the Reynolds number Re as a function of the Chandrasekhar number Ch (the ratio of Lorentz forces to ...

We previously reported bronchial circulation contributes to pulmonary edema and increases shunt fraction following smoke inhalation, and bronchial blood flow significantly increases in inhalation injury. We hypothesized reduction of bronchial blood flow reduces exudation to the airway and ameliorates lung injury from combined burn and smoke insults (B&S injury). METHOD: ...

Forced inspiratory measures have been described to reflect the reduction in dyspnoea upon bronchodilation in severe COPD. Based on this we evaluated the applicability and usefulness of a portable device for the assessment of forced inspiration. In 37 patients with COPD (GOLD II/II/IV n = 16/15/6, mean ± SD FEV(1) 46.2 ± 15.4%pred) lung function was ...

Peripheral chemoreflex sensitivity is potentiated in clinical and experimental chronic heart failure (CHF). Blood supply to tissues is inevitably reduced in CHF. However, it remains poorly understood whether the reduced blood flow is the cause of increased peripheral chemoreflex sensitivity in CHF. This work highlights the effect of chronically reduced ...

Microfluidic techniques are employed to investigate air-liquid flows in the lung. A network of microchannels with five generations is made and used as a simplified model of a section of the pulmonary airway tree. Liquid plugs are injected into the network and pushed by a flow of air; they divide ...

Orthostatic changes induce temporary loss of circulatory regulation. Feedback systems react to cardiovascular alterations to compensate for the instability. To clarify the existence of anticipatory cardiovascular regulation during active standing, we continuously recorded blood flow velocity (BFV) in the common carotid artery and cerebral blood volume (CBV) in healthy men. ...

To investigate the influence of internal carotid artery (ICA) stenosis on the distribution of blood flow to the caudate nucleus, lentiform nucleus, and thalamus. We studied 18 healthy control subjects, 20 patients with a unilateral asymptomatic ICA stenosis, and 15 patients with a recently symptomatic unilateral ICA stenosis. The contribution ...

Patients undergoing carotid endarterectomy for extracranial internal carotid artery stenosis are at risk of cerebral ischemia/hypoperfusion. Criterion recommended by European and American committees to determine whether to place a shunt consisted of a decline in transcranial Doppler ultrasonography-measured middle cerebral artery blood flow velocity (MCBFV) to < 30% to 40% ...

Vascular remodeling is essential to proper vessel function. Dramatic changes in mechanical environment, however, may initiate pathophysiological vascular remodeling processes that lead to vascular disease. Previous work by some of our group has demonstrated a dramatic rise in matrix metalloproteinase (MMP) expression shortly following an abrupt increase in carotid blood ...

The simulated manipulation position is one of several premanipulative screening tests recommended to assist in identifying patients at risk of complications from high velocity thrust manipulation of the cervical spine. The effects of this position on blood flow in the vertebral artery has been measured, but not in the internal ...

Carotid endarterectomy (CEA) is the first-line treatment in severe carotid stenosis to prevent stroke. Because of methodological limitations, the acute impact of CEA on baroreflex function and cerebral autoregulation is not well defined and was therefore investigated by applying a novel algorithm. Systemic arterial blood pressure, ECG and respiration during ...

To better understand the characteristics of erythrocyte aggregation in flowing blood, echogenicity variation in blood was observed both in vitro and in vivo. However, few noninvasive observations of blood echogenicity variation during the cardiac cycle in human arteries have been reported. In the present study, to reduce the dynamic range ...

Matrix metalloproteinases (MMPs) are implicated in the pathogenesis of atherosclerosis. However, the relationship between blood levels of MMPs and the extent of carotid atherosclerosis remains uncertain. We assessed blood levels of active MMPs in relation to the extent of carotid plaque formation and intima-media thickness (IMT) in a community population ...

Carotid artery stenosis due to arteriosclerosis increases the risk of cerebral ischemia via embolic phenomena or reduced blood flow. The changes in cerebral perfusion that may occur after treatment are not clearly understood. This study evaluated the changes in cerebral microcirculation following carotid angioplasty with stenting (CAS) under cerebral protection ...

BACKGROUND: To measure by Doppler sonography the blood flow volume (BFV) of the ipsilateral and contralateral extracranial internal carotid arteries (ICAs) and both vertebral arteries (VAs) before and after a carotid endarterectomy (CEA) of the ICA. We correlated the result with the degree of stenosis of the ICA. METHOD: One ...

We assessed the contribution of carotid body chemoreceptors to the ventilatory response to specific CNS hypercapnia in eight unanaesthetized, awake dogs. We denervated one carotid body (CB) and used extracorporeal blood perfusion of the reversibly isolated remaining CB to maintain normal CB blood gases (normoxic, normocapnic perfusate), to inhibit (hyperoxic, ...

INTRODUCTION: The purpose is to investigate the feasibility of magnetic resonance (MR) plaque imaging in predicting the arterial flow impairment (slow-flow phenomenon) during carotid artery stenting (CAS) using a filter-type protection device. METHODS: Thirty-one carotid artery stenotic lesions in 30 patients (28 men and two women; mean age, 71.8 years) ...

Recent studies have reported the association between advanced arterial stiffness and brain small vessel diseases (SVDs). Two possible hemodynamic mechanisms, increases in central blood pressure (BP) and pulsatile flow load to the brain, have been speculated to link arterial stiffness and SVD. The carotid flow augmentation index (AI) has been ...

Cerebrovascular pathologies are extremely complex, due to the multitude of factors acting simultaneously on cerebral hemodynamics. In this work, a mathematical model of cerebral hemodynamics and intracranial pressure (ICP) dynamics, developed in previous years, is extended to account for heterogeneity in cerebral blood flow. The model includes the Circle of ...

While it is widely appreciated that volumetric blood flow rate (VFR) dynamics change with age, there has been no detailed characterization of the typical shape of carotid bifurcation VFR waveforms of older adults. Toward this end, retrospectively gated phase contrast magnetic resonance imaging was used to measure time-resolved VFR waveforms ...

Quantitative information about the geometry of the carotid artery bifurcation may help in predicting the development of atherosclerosis. A geodesic active contours based segmentation method combining both gradient and intensity information was developed for semi-automatic, accurate and robust quantification of the carotid bifurcation angle in Black Blood MRA data. The ...

The study aimed to follow the influence of some hemorheological parameters and mean blood pressure (MBP) on the carotid blood flow asymmetry in 20 patients with chronic unilateral cerebral infarctions (UCI) as compared to 30 patients with transient ischemic attacks (TIAs), 17 patients with risk factors (RF) for cerebrovascular disease ...

Differential vascular remodeling is one of the major mechanisms of heterogeneity in atherosclerosis. The structural and functional heterogeneity between arteries and veins determines the degree of vascular remodeling. Matrix metalloproteases (MMPs) and their tissue inhibitors (TIMPs) play key roles in vascular structural and functional remodeling. We hypothesized that the level ...

PURPOSE: To evaluate in vitro the capture efficiency of a distal protection filter (DPF) used during carotid artery stenting and examine the longitudinal vascular impedance in the presence of a DPF. METHODS: Four approved DPFs (Spider RX, FilterWire EZ, RX Accunet, and FiberNet) were evaluated in a physiologically realistic in ...

BACKGROUND AND OBJECTIVES: The goal of this study was to compare tissue blood flow at various sites before and after stellate ganglion block (SGB) and to discuss the redistribution of tissue blood flow after SGB. METHODS: We studied 16 male Japanese white rabbits. For SGB, the tip of a 26-gauge ...

The volumetric flow rate (VFR) waveform over the cardiac cycle in the cerebral vasculature is a significant factor in many studies, which involve cerebrovascular function. Perhaps contrary to expectation, the literature in this area is sparse and the characteristics of blood flow waveforms are ill defined. A better understanding of ...

BACKGROUND: Arterial spin labeling (ASL) perfusion MRI with image acquisition at multiple delay times can be used to measure delays in the arrival of arterial blood to the brain. We assessed the effect of a symptomatic internal carotid artery (ICA) stenosis on ASL timing parameters, and evaluated the effect of ...

BACKGROUND: The brain collateral blood supply, which is essential in patients suffering from significant stenoses or occlusions of the extracranial arteries, remains difficult to assess accurately in practice. We compared data obtained from transcranial color-coded duplex sonography (TCCD) combined with carotid compression tests to morphometric autopsy data and to results ...

OBJECTIVE: The collateral function of the external carotid artery (ECA) for cerebral perfusion in cases of atherosclerotic occlusive disease of the internal carotid artery (ICA) is difficult to assess; for this reason, blood flow measurements were taken during carotid endarterectomy (CEA). METHODS: Blood flow was measured before and after CEA ...

PURPOSE: The objective of this study was to evaluate the role of cerebral perfusion computed tomography (CT) in predicting cerebral hyperperfusion syndrome (CHS) after carotid stenting. MATERIALS AND METHODS: This study was approved by the institutional review board, and written informed consent was obtained from all patients. Fifty-five consecutive symptomatic ...

The use of two clinic office techniques, carotid artery ultrasound and echocardiography (CAUSE), to detect deficient brain blood flow delivery in the healthy, cognitively normal, older individual is proposed. Evidence indicates that persistent heart-to-brain blood flow deficit involving low cardiac output or low ejection fraction and carotid artery narrowing can ...

Vascular remodeling associated with increased blood flow involves reactive oxygen species (ROS)-dependent activation of matrix metalloproteinases (MMPs). To investigate the potential role of NF-kappaB in this process, human umbilical vein endothelial cells were subjected to different flow conditions during a 24-h period. Normal (15 dynes/cm(2)) and high (30 dynes/cm(2)) shear ...

Sustained hemodynamic stresses, especially high blood flow, result in flow-induced outward vascular remodeling. Our previous study showed that macrophage depletion reduced flow-induced outward remodeling of the rat common carotid artery, indicating that macrophages are critical in flow-induced outward vascular remodeling. Macrophage is known to release proteinases, including matrix metalloproteinases (MMPs). ...

OBJECTIVE: Cardiovascular (CV) risk relates to the blood flow velocity pattern in the brachial artery during hyperemia, especially to the hyperaemic systolic to diastolic mean blood flow velocity (SDFV) ratio. Here, we investigated the relations between SDFV in the brachial artery and different characteristics of carotid atherosclerosis. MATERIAL AND METHODS: ...

OBJECTIVE: Cerebral hyperperfusion after carotid endarterectomy (CEA) occurs in patients with preoperative impairments in cerebral hemodynamics. Signal intensity of the middle cerebral artery (MCA) on single-slab 3-dimensional time-of-flight magnetic resonance angiography (MRA) can assess hemodynamic impairment in the cerebral hemisphere. The purpose of the present study was to determine whether ...

Detection and prevention of atherosclerosis at an early stage is important for its prevention. The aim of this study was to propose a valid and highly reliable index for the evaluation of carotid atherosclerosis or carotid function. Images of carotid Doppler wave profiles were processed using an image processing software, ...

AIM: Voluntary apnoea induces several physiological adaptations, including bradycardia, arterial hypertension and redistribution of regional blood flows. Elite breath-hold divers (BHDs) are able to maintain very long apnoea, inducing severe hypoxaemia without brain injury or black-out. It has thus been hypothesized that they develop protection mechanisms against hypoxia, as well ...

To determine three-dimensional (3D) blood flow patterns in the carotid bifurcation, 10 healthy volunteers and nine patients with internal carotid artery (ICA) stenosis > or =50% were examined by flow-sensitive 4D MRI at 3T. Absolute and mean blood velocities, pulsatility index (PI), and resistance index (RI) were measured in the ...

A group of 72 patients with 111 asymptomatic carotid stenoses (ACS), mean age 65.42 +/- 9.21, and a group of 36 patients with 58 symptomatic carotid stenoses (SCS), mean age 67.63 +/- 8.79, were analyzed prospectively during a 3-year follow-up period. All patients underwent color duplex scan sonography (CDS), carotid ...

To determine blood volume flow (BVF) in the brain-supplying arteries in patients with fibromuscular dysplasia (FMD), we used two-dimensional cine phase-contrast MR blood flow quantification to evaluate haemodynamic compromise. Nine patients with angiographically proven FMD (mean age, 46.7+/-10.4 years) of the cervical and intracranial arteries were examined using two-dimensional phase ...

Pathological extremes in cerebrovascular remodeling may contribute to basilar artery (BA) dolichoectasia and fusiform aneurysm development. Factors regulating cerebrovascular remodeling are poorly understood. To better understand hemodynamic influences on cerebrovascular remodeling, we examined BA remodeling following common carotid artery (CCA) ligation in an animal model. Rabbits were subjected to sham ...

BACKGROUND: During regional anesthesia for carotid endarterectomy (CEA), 10% to 15% of patients develop signs of cerebral hypoxia after cross-clamping, manifested as changes in speech, cerebration or contralateral motor power. Reversal of such neurological deficits using administration of 100% O2 has been described. We used near-infrared cerebral oximetry to assess ...

Cardiopulmonary resuscitation (CPR) is now widely used as a treatment for ventricular fibrillation, though numerous studies have shown the outcome of standard CPR to be dismal. Alternative methods of CPR, including interposed abdominal compression, constant aortic occlusion, and the use of intrathoracic pressure regulator, have been shown to increase cardiac ...

The amphibian carotid labyrinth was first described in 1738, but its purpose has never been satisfactorily explained. Much of the extant literature has either been restricted to a particular aspect of the organ, or has been based on erroneous information. This thesis used the New Zealand frog Leiopelma hochstetteri because ...

Numerical modelling is a powerful tool in the investigation of human blood flow and arterial diseases such as atherosclerosis. It is known that near wall velocity and shear are important in the pathogenesis and progression of atherosclerosis. In this paper results for a simulation of blood flow in a three-dimensional ...