Calcium channel blocker poisoning

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Miran Brvar

2005-04-01

Full Text Available Background: Calcium channel blockers act at L-type calcium channels in cardiac and vascular smooth muscles by preventing calcium influx into cells with resultant decrease in vascular tone and cardiac inotropy, chronotropy and dromotropy. Poisoning with calcium channel blockers results in reduced cardiac output, bradycardia, atrioventricular block, hypotension and shock. The findings of hypotension and bradycardia should suggest poisoning with calcium channel blockers.Conclusions: Treatment includes immediate gastric lavage and whole-bowel irrigation in case of ingestion of sustainedrelease products. All patients should receive an activated charcoal orally. Specific treatment includes calcium, glucagone and insulin, which proved especially useful in shocked patients. Supportive care including the use of catecholamines is not always effective. In the setting of failure of pharmacological therapy transvenous pacing, balloon pump and cardiopulmonary by-pass may be necessary.

Calcium channel blockers, more than diuretics, enhance vascular protective effects of angiotensin receptor blockers in salt-loaded hypertensive rats.

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Eiichiro Yamamoto

Full Text Available The combination therapy of an angiotensin receptor blocker (ARB with a calcium channel blocker (CCB or with a diuretic is favorably recommended for the treatment of hypertension. However, the difference between these two combination therapies is unclear. The present work was undertaken to examine the possible difference between the two combination therapies in vascular protection. Salt-loaded stroke-prone spontaneously hypertensive rats (SHRSP were divided into 6 groups, and they were orally administered (1 vehicle, (2 olmesartan, an ARB, (3 azelnidipine, a CCB, (4 hydrochlorothiazide, a diuretic, (5 olmesartan combined with azelnidipine, or (6 olmesartan combined with hydrochlorothiazide. Olmesartan combined with either azelnidipine or hydrochlorothiazide ameliorated vascular endothelial dysfunction and remodeling in SHRSP more than did monotherapy with either agent. However, despite a comparable blood pressure lowering effect between the two treatments, azelnidipine enhanced the amelioration of vascular endothelial dysfunction and remodeling by olmesartan to a greater extent than did hydrochlorothiazide in salt-loaded SHRSP. The increased enhancement by azelnidipine of olmesartan-induced vascular protection than by hydrochlorothiazide was associated with a greater amelioration of vascular nicotinamide adenine dinucleotide phosphate (NADPH oxidase activation, superoxide, mitogen-activated protein kinase activation, and with a greater activation of the Akt/endothelial nitric oxide synthase (eNOS pathway. These results provided the first evidence that a CCB potentiates the vascular protective effects of an ARB in salt-sensitive hypertension, compared with a diuretic, and provided a novel rationale explaining the benefit of the combination therapy with an ARB and a CCB.

Whole-body MRI: comprehensive evaluation on a 48-channel 3T MRI system in less than 40 minutes. Preliminary results

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Mateus de Andrade Hernandes

2012-12-01

Full Text Available OBJECTIVE: To evaluate a comprehensive MRI protocol that investigates for cancer, vascular disease, and degenerative/inflammatory disease from the head to the pelvis in less than 40 minutes on a new generation 48-channel 3T system. MATERIALS AND METHODS: All MR studies were performed on a 48-channel 3T MR scanner. A 20-channel head/neck coil, two 18-channel body arrays, and a 32-channel spine array were employed. A total of 4 healthy individuals were studied. The designed protocol included a combination of single-shot T2-weighted sequences, T1-weighted 3D gradient-echo pre- and post-gadolinium. All images were retrospectively evaluated by two radiologists independently for overall image quality. RESULTS: The image quality for cancer was rated as excellent in the liver, pancreas, kidneys, lungs, pelvic organs, and brain, and rated as fair in the colon and breast. For vascular diseases ratings were excellent in the aorta, major branch vessel origins, inferior vena cava, portal and hepatic veins, rated as good in pulmonary arteries, and as poor in the coronary arteries. For degenerative/inflammatory diseases ratings were excellent in the brain, liver and pancreas. The inter-observer agreement was excellent. CONCLUSION: A comprehensive and time efficient screening for important categories of disease processes may be achieved with high quality imaging in a new generation 48-channel 3T system.

Whole-body MRI: comprehensive evaluation on a 48-channel 3T MRI system in less than 40 minutes. Preliminary results

Energy Technology Data Exchange (ETDEWEB)

Hernandes, Mateus de Andrade; Semelka, Richard C.; Bamrungchart, Saraporn; Stallings, Clifton, E-mail: richsem@med.unc.edu [Department of Radiology, University of North Carolina, Chapel Hill, NC (United States); Elias Junior, Jorge [Imaging and Medical Physics Center, School of Medicine of Ribeirao Preto, University of Sao Paulo, Ribeirao Preto, SP (Brazil); Dale, Brian M. [Siemens Medical Solutions USA, Inc., Cary, NC (United States)

2012-11-15

Objective: To evaluate a comprehensive MRI protocol that investigates for cancer, vascular disease, and degenerative/inflammatory disease from the head to the pelvis in less than 40 minutes on a new generation 48-channel 3T system. Materials and Methods: All MR studies were performed on a 48-channel 3T MR scanner. A 20-channel head/neck coil, two 18-channel body arrays, and a 32-channel spine array were employed. A total of 4 healthy individuals were studied. The designed protocol included a combination of single-shot T2-weighted sequences, T1-weighted 3D gradient echo pre- and post-gadolinium. All images were retrospectively evaluated by two radiologists independently for overall image quality. Results: The image quality for cancer was rated as excellent in the liver, pancreas, kidneys, lungs, pelvic organs, and brain, and rated as fair in the colon and breast. For vascular diseases ratings were excellent in the aorta, major branch vessel origins, inferior vena cava, portal and hepatic veins, rated as good in pulmonary arteries, and as poor in the coronary arteries. For degenerative/inflammatory diseases ratings were excellent in the brain, liver and pancreas. The inter-observer agreement was excellent. Conclusion: A comprehensive and time efficient screening for important categories of disease processes may be achieved with high quality imaging in a new generation 48-channel 3T system. (author)

Chronic deficit in nitric oxide elicits oxidative stress and augments T-type calcium-channel contribution to vascular tone of rodent arteries and arterioles

DEFF Research Database (Denmark)

Howitt, Lauren; Kuo, Ivana Y; Ellis, Anthie

2013-01-01

arteries in vitro and skeletal muscle arterioles in vivo to study the contribution of L-type (1 µmol/L nifedipine) and T-type (1 µmol/L mibefradil, 3 µmol/L NNC 55-0396) calcium channels to vascular tone, following acute or chronic inhibition of nitric oxide. Acute inhibition with l-NAME (10 µmol...... was reversed by acute scavenging of superoxide with tempol (1 mmol/L), or inhibition of NADPH oxidase with apocynin (500 µmol/L) or DPI (5 µmol/L). CONCLUSION: We conclude that nitric oxide deficit produces a significant increase in the contribution of Cav3.1 and Cav3.2 T-type calcium channels to vascular tone......, by regulating the bioavailability of reactive oxygen species produced by NADPH oxidase. Our data provide evidence for a novel causal link between nitric oxide deficit, oxidative stress, and T-type calcium channel function....

Coexpression of voltage-dependent calcium channels Cav1.2, 2.1a, and 2.1b in vascular myocytes

DEFF Research Database (Denmark)

Andreasen, Ditte; Friis, Ulla G; Uhrenholt, Torben R

2006-01-01

Voltage-dependent Ca2+ channels Cav1.2 (L type) and Cav2.1 (P/Q type) are expressed in vascular smooth muscle cells (VSMCs) and are important for the contraction of renal resistance vessels. In the present study we examined whether native renal VSMCs coexpress L-, P-, and Q-type Ca2+ currents...... microscopy revealed expression of both channels in all of the smooth muscle cells. Whole-cell patch clamp on single preglomerular VSMCs from mice showed L-, P-, and Q-type currents. Blockade of the L-type currents by calciseptine (20 nmol/L) inhibited 35.6+/-3.9% of the voltage-dependent Ca2+ current......-type and P-type channels inhibited 58.0+/-11.8%, and simultaneous inhibition of L-, P-, and Q-type channels led to blockade (88.7+/-5.6%) of the Ca2+ current. We conclude that aortic and renal preglomerular smooth muscle cells express L-, P-, and Q-type voltage-dependent Ca2+ channels in the rat and mouse....

Modulation of CaV1.2 calcium channel by neuropeptide W regulates vascular myogenic tone via G protein-coupled receptor 7.

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Ji, Li; Zhu, Huayuan; Chen, Hong; Fan, Wenyong; Chen, Junjie; Chen, Jing; Zhu, Guoqing; Wang, Juejin

2015-12-01

Neuropeptide W (NPW), an endogenous ligand for the G protein-coupled receptor 7 (GPR7), was first found to make important roles in central nerve system. In periphery, NPW was also present and regulated intracellular calcium homeostasis by L-type calcium channels. This study was designed to discover the effects of NPW-GPR7 on the function of CaV1.2 calcium channels in the vascular smooth muscle cells (VSMCs) and vasotone of arterial vessels. By whole-cell patch clamp, we studied the effects of NPW-23, the active form of NPW, on the CaV1.2 channels in the heterologously transfected human embryonic kidney 293 cells and VSMCs isolated from rat. Living system was used to explore the physiological function of NPW-23 in arterial myogenic tone. To investigate the pathological relevance, NPW mRNA level of mesenteric arteries was measured in the hypertensive and normotensive rats. NPW's receptor GPR7 was coexpressed with CaV1.2 channels in arterial smooth muscle. NPW-23 increased the ICa,L in transfected human embryonic kidney 293 cells and VSMCs via GPR7, which could be abrogated by phospholipase C (PLC)/protein kinase C (PKC) inhibitors, not protein kinase A or protein kinase G inhibitor. After NPW-23 application, the expression of pan phospho-PKC was increased; moreover, intracellular diacylglycerol level, the second messenger catalyzed by PLC, was increased 1.5-2-fold. Application with NPW-23 increased pressure-induced vasotone of the rat mesenteric arteries. Importantly, the expression of NPW was decreased in the hypertensive rats. NPW-23 regulates ICa,L via GPR7, which is mediated by PLC/PKC signaling, and such a mechanism plays a role in modulating vascular myogenic tone, which may involve in the development of vascular hypertension.

3D bioprinting for vascularized tissue fabrication

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Richards, Dylan; Jia, Jia; Yost, Michael; Markwald, Roger; Mei, Ying

2016-01-01

3D bioprinting holds remarkable promise for rapid fabrication of 3D tissue engineering constructs. Given its scalability, reproducibility, and precise multi-dimensional control that traditional fabrication methods do not provide, 3D bioprinting provides a powerful means to address one of the major challenges in tissue engineering: vascularization. Moderate success of current tissue engineering strategies have been attributed to the current inability to fabricate thick tissue engineering constructs that contain endogenous, engineered vasculature or nutrient channels that can integrate with the host tissue. Successful fabrication of a vascularized tissue construct requires synergy between high throughput, high-resolution bioprinting of larger perfusable channels and instructive bioink that promotes angiogenic sprouting and neovascularization. This review aims to cover the recent progress in the field of 3D bioprinting of vascularized tissues. It will cover the methods of bioprinting vascularized constructs, bioink for vascularization, and perspectives on recent innovations in 3D printing and biomaterials for the next generation of 3D bioprinting for vascularized tissue fabrication. PMID:27230253

Update on vascular endothelial Ca(2+) signalling: A tale of ion channels, pumps and transporters.

Science.gov (United States)

Moccia, Francesco; Berra-Romani, Roberto; Tanzi, Franco

2012-07-26

A monolayer of endothelial cells (ECs) lines the lumen of blood vessels and forms a multifunctional transducing organ that mediates a plethora of cardiovascular processes. The activation of ECs from as state of quiescence is, therefore, regarded among the early events leading to the onset and progression of potentially lethal diseases, such as hypertension, myocardial infarction, brain stroke, and tumor. Intracellular Ca(2+) signals have long been know to play a central role in the complex network of signaling pathways regulating the endothelial functions. Notably, recent work has outlined how any change in the pattern of expression of endothelial channels, transporters and pumps involved in the modulation of intracellular Ca(2+) levels may dramatically affect whole body homeostasis. Vascular ECs may react to both mechanical and chemical stimuli by generating a variety of intracellular Ca(2+) signals, ranging from brief, localized Ca(2+) pulses to prolonged Ca(2+) oscillations engulfing the whole cytoplasm. The well-defined spatiotemporal profile of the subcellular Ca(2+) signals elicited in ECs by specific extracellular inputs depends on the interaction between Ca(2+) releasing channels, which are located both on the plasma membrane and in a number of intracellular organelles, and Ca(2+) removing systems. The present article aims to summarize both the past and recent literature in the field to provide a clear-cut picture of our current knowledge on the molecular nature and the role played by the components of the Ca(2+) machinery in vascular ECs under both physiological and pathological conditions.

Update on vascular endothelial Ca2+ signalling: A tale of ion channels, pumps and transporters

Science.gov (United States)

Moccia, Francesco; Berra-Romani, Roberto; Tanzi, Franco

2012-01-01

A monolayer of endothelial cells (ECs) lines the lumen of blood vessels and forms a multifunctional transducing organ that mediates a plethora of cardiovascular processes. The activation of ECs from as state of quiescence is, therefore, regarded among the early events leading to the onset and progression of potentially lethal diseases, such as hypertension, myocardial infarction, brain stroke, and tumor. Intracellular Ca2+ signals have long been know to play a central role in the complex network of signaling pathways regulating the endothelial functions. Notably, recent work has outlined how any change in the pattern of expression of endothelial channels, transporters and pumps involved in the modulation of intracellular Ca2+ levels may dramatically affect whole body homeostasis. Vascular ECs may react to both mechanical and chemical stimuli by generating a variety of intracellular Ca2+ signals, ranging from brief, localized Ca2+ pulses to prolonged Ca2+ oscillations engulfing the whole cytoplasm. The well-defined spatiotemporal profile of the subcellular Ca2+ signals elicited in ECs by specific extracellular inputs depends on the interaction between Ca2+ releasing channels, which are located both on the plasma membrane and in a number of intracellular organelles, and Ca2+ removing systems. The present article aims to summarize both the past and recent literature in the field to provide a clear-cut picture of our current knowledge on the molecular nature and the role played by the components of the Ca2+ machinery in vascular ECs under both physiological and pathological conditions. PMID:22905291

Downregulation of Kv7.4 channel activity in primary and secondary hypertension

DEFF Research Database (Denmark)

Jepps, Thomas Andrew; Chadha, Preet S; Davis, Alison J

2011-01-01

Voltage-gated potassium (K(+)) channels encoded by KCNQ genes (Kv7 channels) have been identified in various rodent and human blood vessels as key regulators of vascular tone; however, nothing is known about the functional impact of these channels in vascular disease. We ascertained the effect of...... structurally different activators of Kv7.2 through Kv7.5 channels (BMS-204352, S-1, and retigabine) on blood vessels from normotensive and hypertensive animals.......Voltage-gated potassium (K(+)) channels encoded by KCNQ genes (Kv7 channels) have been identified in various rodent and human blood vessels as key regulators of vascular tone; however, nothing is known about the functional impact of these channels in vascular disease. We ascertained the effect of 3...

Statin therapy exacerbates alcohol-induced constriction of cerebral arteries via modulation of ethanol-induced BK channel inhibition in vascular smooth muscle.

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Simakova, Maria N; Bisen, Shivantika; Dopico, Alex M; Bukiya, Anna N

2017-12-01

Statins constitute the most commonly prescribed drugs to decrease cholesterol (CLR). CLR is an important modulator of alcohol-induced cerebral artery constriction (AICAC). Using rats on a high CLR diet (2% CLR) we set to determine whether atorvastatin administration (10mg/kg daily for 18-23weeks) modified AICAC. Middle cerebral arteries were pressurized in vitro at 60mmHg and AICAC was evoked by 50mM ethanol, that is within the range of blood alcohol detected in humans following moderate-to-heavy drinking. AICAC was evident in high CLR+atorvastatin group but not in high CLR diet+placebo. Statin exacerbation of AICAC persisted in de-endothelialized arteries, and was blunted by CLR enrichment in vitro. Fluorescence imaging of filipin-stained arteries showed that atorvastatin decreased vascular smooth muscle (VSM) CLR when compared to placebo, this difference being reduced by CLR enrichment in vitro. Voltage- and calcium-gated potassium channels of large conductance (BK) are known VSM targets of ethanol, with their beta1 subunit being necessary for ethanol-induced channel inhibition and resulting AICAC. Ethanol-induced BK inhibition in excised membrane patches from freshly isolated myocytes was exacerbated in the high CLR diet+atorvastatin group when compared to high CLR diet+placebo. Unexpectedly, atorvastatin decreased the amount and function of BK beta1 subunit as documented by immunofluorescence imaging and functional patch-clamp studies. Atorvastatin exacerbation of ethanol-induced BK inhibition disappeared upon artery CLR enrichment in vitro. Our study demonstrates for the first time statin's ability to exacerbate the vascular effect of a widely consumed drug of abuse, this exacerbation being driven by statin modulation of ethanol-induced BK channel inhibition in the VSM via CLR-mediated mechanism. Copyright © 2017 Elsevier Inc. All rights reserved.

Potassium channels as drugs targets in therapy of cardiovascular diseases: 25 years later

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Protić Dragana

2013-03-01

Full Text Available Potassium channels are the most variable ion channel group. They participate in numerous cardiovascular functions, for example regulation of vascular tone, maintenance of resting cardiac membrane potential and excitability of cardiac conduction tissue. Both drugs and endogenous ligands could modulate potassium channel function, belonging to the potassium channel blockers or openers. Modulation of potassium channels could be a therapeutic or adverse drug action. Class III antiarrhythmic agents block the potassium channels, thereby prolonging repolarization phase of action potential with resulting prolongation of effective refractory period. Their effectiveness against supraventricular and ventricular arrhythmias should be weighted against their proarrhythmogenic potential. In addition, numerous other antiarrhythmic agents could modulate potassium channels as well. Diazoxide, minoxidil and nicorandil (well known arterial vasodilators, as well as numerous newly synthesized substances with still unknown therapeutic potential, belong to the potassium channel activators/openers. Therapeutic use of such vasodilators may involve treatment of hypertension (diazoxide, minoxidil and stable angina (nicorandil. Their use might be accompanied with side effects, such as vasodilation, edema, hypotension and reflex tachycardia. Potassium channel openers have also an important role in the treatment of peripheral vascular disease and pulmonary hypertension. In the future, drugs with selective effects on the vascular or cardiac potassium channels could be useful therapeutic agents.

POTASSIUM CHANNELS AS DRUGS TARGETS IN THERAPY OF CARDIOVASCULAR DESEASES: 25 YEARS LATER

Directory of Open Access Journals (Sweden)

Protić Dragana

2013-01-01

Full Text Available Potassium channels are the most variable ion channel group. They participate in numerous cardiovascular functions, for example regulation of vascular tone, maintenance of resting cardiac membrane potential and excitability of cardiac conduction tissue. Both drugs and endogenous ligands could modulate potassium channel function, belonging to the potassium channel blockers or openers. Modulation of potassium channels could be a therapeutic or adverse drug action. Class III antiarrhythmic agents block the potassium channels, thereby prolonging repolarization phase of action potential with resulting prolongation of effective refractory period. Their effectiveness against supraventricular and ventricular arrhythmias should be weighted against their proarrhythmogenic potential. In addition, numerous other antiarrhythmic agents could modulate potassium channels as well. Diazoxide, minoxidil and nicorandil (well known arterial vasodilators, as well as numerous newly synthesized substances with still unknown therapeutic potential, belong to the potassium channel activators/ openers. Therapeutic use of such vasodilators may involve treatment of hypertension (diazoxide, minoxidil and stable angina (nicorandil. Their use might be accompanied with side effects, such as vasodilation, edema, hypotension and reflex tachycardia. Potassium channel openers have also an important role in the treatment of peripheral vascular disease and pulmonary hypertension. In the future, drugs with selective effects on the vascular or cardiac potassium channels could be useful therapeutic agents.

Magnetic resonance venography of congenital vascular malformations of the extremities

International Nuclear Information System (INIS)

Laor, T.; Burrows, P.E.; Hoffer, F.A.

1996-01-01

Contrast angiography can demonstrate the vascular components of a vascular malformation, but can be technically challenging in small patients with complex venous anomalies. We reviewed the role of magnetic resonance venography (MRV) in the evaluation of children with predominantly low-flow, vascular malformations of the extremities. MRV (2D time-of-flight technique) and magnetic resonance (MR) imaging examinations were performed in ten young patients with congential predominantly low-flow vascular malformations of the extremities. MR imaging was used to characterize and determine the extent of the malformations, and MRV to evaluate the deep and superficial venous channels. In all patients, MRV studies were reviewed in conjunction with contrast angiograms, considered the gold standard, to confirm the findings. All signficant channel anomalies seen with contrast angiography were identified with MRV. In addition, MRV demonstrated some veins that were not intentionally opacified during contrast studies. MRV demonstrates both the superficial and deep conducting veins, whereas contrast angiography is a more directed study, evaluating only those channels intentionally opacified. Together, MR imaging and MRV data can non-invasively form the basis for determining the prognosis and choosing the individual treatment of congenital vascular malformations of the extremities. (orig.)

Kcne4 Deletion Sex-Dependently Alters Vascular Reactivity

DEFF Research Database (Denmark)

Abbott, Geoffrey W; Jepps, Thomas A

2016-01-01

transcripts, with no striking sex-specific differences. However, Kv7.4 protein expression in females was twice that in males, and was reduced in both sexes by Kcne4 deletion. Our findings confirm a crucial role for KCNE4 in regulation of Kv7 channel activity to modulate vascular tone, and provide the first......Voltage-gated potassium (Kv) channels formed by Kv7 (KCNQ) α-subunits are recognized as crucial for vascular smooth muscle function, in addition to their established roles in the heart (Kv7.1) and the brain (Kv7.2-5). In vivo, Kv7 α-subunits are often regulated by KCNE subfamily ancillary (β...... known molecular mechanism for sex-specificity of this modulation that has important implications for vascular reactivity and may underlie sex-specific susceptibility to cardiovascular diseases....

Functional and pharmacological consequences of the distribution of voltage-gated calcium channels in the renal blood vessels

DEFF Research Database (Denmark)

Hansen, P B L

2013-01-01

Calcium channel blockers are widely used to treat hypertension because they inhibit voltage-gated calcium channels that mediate transmembrane calcium influx in, for example, vascular smooth muscle and cardiomyocytes. The calcium channel family consists of several subfamilies, of which the L......-type is usually associated with vascular contractility. However, the L-, T- and P-/Q-types of calcium channels are present in the renal vasculature and are differentially involved in controlling vascular contractility, thereby contributing to regulation of kidney function and blood pressure. In the preglomerular...... vascular bed, all the three channel families are present. However, the T-type channel is the only channel in cortical efferent arterioles which is in contrast to the juxtamedullary efferent arteriole, and that leads to diverse functional effects of L- and T-type channel inhibition. Furthermore...

Chronic Prenatal Hypoxia Down-Regulated BK Channel Β1 Subunits in Mesenteric Artery Smooth Muscle Cells of the Offspring

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Bailin Liu

2018-02-01

Full Text Available Background/Aims: Chronic hypoxia in utero could impair vascular functions in the offspring, underlying mechanisms are unclear. This study investigated functional alteration in large-conductance Ca2+-activated K+ (BK channels in offspring mesenteric arteries following prenatal hypoxia. Methods: Pregnant rats were exposed to normoxic control (21% O2, Con or hypoxic (10.5% O2, Hy conditions from gestational day 5 to 21, their 7-month-old adult male offspring were tested for blood pressure, vascular BK channel functions and expression using patch clamp and wire myograh technique, western blotting, and qRT-PCR. Results: Prenatal hypoxia increased pressor responses and vasoconstrictions to phenylephrine in the offspring. Whole-cell currents density of BK channels and amplitude of spontaneous transient outward currents (STOCs, not the frequency, were significantly reduced in Hy vascular myocytes. The sensitivity of BK channels to voltage, Ca2+, and tamoxifen were reduced in Hy myocytes, whereas the number of channels per patch and the single-channel conductance were unchanged. Prenatal hypoxia impaired NS1102- and tamoxifen-mediated relaxation in mesenteric arteries precontracted with phenylephrine in the presence of Nω-nitro-L-arginine methyl ester. The mRNA and protein expression of BK channel β1, not the α-subunit, was decreased in Hy mesenteric arteries. Conclusions: Impaired BK channel β1-subunits in vascular smooth muscle cells contributed to vascular dysfunction in the offspring exposed to prenatal hypoxia.

Experimental results and clinical impact of using autologous rectus fascia sheath for vascular replacement

NARCIS (Netherlands)

Kobori, Laszlo; Nemeth, Tibor; Nagy, Peter; Dallos, Gabor; Sotonyi, Peter; Fehervari, Imre; Nemes, Balazs; Gorog, Denes; Patonai, Attila; Monostory, Katalin; Doros, Attila; Sarvary, Enikoe; Fazakas, Janos; Gerlei, Zsuzsanna; Benkoe, Tamas; Piros, Laszlo; Jaray, Jeno; De Jong, Koert P.

Vascular complications are major causes of graft failure in liver transplantation. The use of different vascular grafts is common but the results are controversial. The aim of this study was to create an 'ideal' arterial interponate for vascular replacements in the clinical field. An autologous,

New Role of P/Q-type Voltage-gated Calcium Channels

DEFF Research Database (Denmark)

Hansen, Pernille B L

2015-01-01

Voltage-gated calcium channels are important for the depolarization-evoked contraction of vascular smooth muscle cells (SMCs), with L-type channels being the classical channel involved in this mechanism. However, it has been demonstrated that the CaV2.1 subunit, which encodes a neuronal isoform...... of the voltage-gated calcium channels (P/Q-type), is also expressed and contributes functionally to contraction of renal blood vessels in both mice and humans. Furthermore, preglomerular vascular SMCs and aortic SMCs coexpress L-, P-, and Q-type calcium channels within the same cell. Calcium channel blockers...... are widely used as pharmacological treatments. However, calcium channel antagonists vary in their selectivity for the various calcium channel subtypes, and the functional contribution from P/Q-type channels as compared with L-type should be considered. Confirming the presence of P/Q-type voltage...

Correct diagnosis of vascular encasement and longitudinal extension of hilar cholangiocarcinoma by four-channel multidetector-row computed tomography

International Nuclear Information System (INIS)

Okumoto, Tadayuki; Yamada, Takayuki; Sato, Akihiro

2009-01-01

Accurate diagnosis of local invasion of hilar cholangiocarcinomas is challenging due to their small size and the anatomic complexity of the hepatic hilar region. On the other hand, the correct diagnosis of local invasion is essential for assuring the possibility of curative surgery. The purpose of this study was to evaluate the feasibility of four-channel multidetector-row computed tomography (MDCT) in the assessment of vascular and bile duct involvement, by which we could obtain useful information for the surgical management of hilar cholangiocarcinoma. The subjects were 18 patients for whom the extent of tumor invasion was surgically and pathologically confirmed. All patients underwent preoperative multiphasic CT scanning by MDCT. Arterial and portal dominant phases were acquired using a detector configuration of 1.25 mm x 4 mm, and both axial and multiplanar reconstructed images were interpreted. Longitudinal extension was evaluated up to second-order branches. Vascular invasion is considered to be the degree of tumor contiguity to the hepatic arteries and portal vein and was graded by CT. The longitudinal extension was correctly diagnosed in 14 patients (77.8%). Hepatic artery invasion was correctly diagnosed in 17 patients with sensitivity of 100% and specificity of 90%, respectively. Portal vein invasion was correctly diagnosed in 47 of 51 branches with sensitivity and specificity of 92.3% and 90.2%, respectively. Multiplanar reconstructed images contributed to the correct diagnosis for both vascular encasement and longitudinal tumor extension. In conclusion, MDCT is useful in preoperative evaluation of hilar cholangiocarcinoma, especially when combined with multiplanar reconstructed images. (author)

5,6-EET potently inhibits T-type calcium channels

DEFF Research Database (Denmark)

Cazade, M.; Bidaud, I.; Hansen, Pernille B. Lærkegaard

2014-01-01

T-type calcium channels (T-channels) are important actors in neuronal pacemaking, in heart rhythm, and in the control of the vascular tone. T-channels are regulated by several endogenous lipids including the primary eicosanoid arachidonic acid (AA), which display an important role in vasodilation...

Effect of gamma rays on electrically evoked contractions of non-vascular smooth muscles (rat vas deferens)

International Nuclear Information System (INIS)

Azroony, R.; Ksies, F.; Alya, G.

2002-10-01

We have tried, in this experiment, to study the modifications of non-vascular smooth muscles contraction induced via gamma rays. Smooth muscular fibers were isolated from the vas deferens of an adult rat and contractions were electrically evoked. Our results show that irradiation activates the VOC (Voltage Operated Channel) type of ionic channels which causes an increasing in the inward flux of Ca 2+ and then causes an increasing in the inner calcium concentration [Ca 2] i, the matter which means an increasing in the force of muscular contraction. Concerning to the response of vas deferens smooth muscles to the activation of membrane receptors, we have tried to study the effects of gamma rays on activating adrenergic and cholinergic receptors, also, we have tried to show the effects of different doses of gamma rays (1, 3, 5, 7 Gy) on regulating the contractile response of this type of smooth muscles. And results show that: - Irradiation increases contraction force, mediated by adrenergic and cholinergic receptors, in a dose dependent manner, with E m ax 1 Gy m axc 3 Gy m ax 5 Gy m ax 7 Gy. There is an important shift on irradiated rats (3, 5, 7 Gy) where the maximum effect of Acetylcholine (E m ax) can be obtained in lower concentrations of Acetylcholine. These results mean that irradiation activates the inward flux of Ca 2+ through the ROC (Receptors Operated Channels) type of ionic channels, which rely, in their activation, on activating the membrane receptors. By comparing these results with the effects of gamma rays on activating vascular adrenergic and cholinergic receptors, we concluded that: Non-vascular smooth muscles (vas deferens) are less sensitive to irradiation in comparing with vascular smooth muscles (venae portal hepatica), and irradiation increases the sensitivity of cholinergic receptors to acetylcholine in the smooth muscular fibers of vas deferens while; if decreases this sensitivity in the smooth muscular fibers of venae portal hepatica

Results of the examination of channel H12/1

International Nuclear Information System (INIS)

Bauer, E.

1983-01-01

Channel H12/1 is one part of the channel unit of the High-Flux Reactor that has been affected by corrosion attack. It was disassembled after the appearance of a heavy water leak and examined in a hot cell. Results of the examination are presented

Soluble adenylyl cyclase in vascular endothelium: gene expression control of epithelial sodium channel-α, Na+/K+-ATPase-α/β, and mineralocorticoid receptor.

Science.gov (United States)

Schmitz, Boris; Nedele, Johanna; Guske, Katrin; Maase, Martina; Lenders, Malte; Schelleckes, Michael; Kusche-Vihrog, Kristina; Brand, Stefan-Martin; Brand, Eva

2014-04-01

The Ca(2+)- and bicarbonate-activated soluble adenylyl cyclase (sAC) has been identified recently as an important mediator of aldosterone signaling in the kidney. Nuclear sAC has been reported to stimulate cAMP response element-binding protein 1 phosphorylation via protein kinase A, suggesting an alternative cAMP pathway in the nucleus. In this study, we analyzed the sAC as a potential modulator of endothelial stiffness in the vascular endothelium. We determined the contribution of sAC to cAMP response element-mediated transcriptional activation in vascular endothelial cells and kidney collecting duct cells. Inhibition of sAC by the specific inhibitor KH7 significantly reduced cAMP response element-mediated promoter activity and affected cAMP response element-binding protein 1 phosphorylation. Furthermore, KH7 and anti-sAC small interfering RNA significantly decreased mRNA and protein levels of epithelial sodium channel-α and Na(+)/K(+)-ATPase-α. Using atomic force microscopy, a nano-technique that measures stiffness and deformability of living cells, we detected significant endothelial cell softening after sAC inhibition. Our results suggest that the sAC is a regulator of gene expression involved in aldosterone signaling and an important regulator of endothelial stiffness. Additional studies are warranted to investigate the protective action of sAC inhibitors in humans for potential clinical use.

The endothelial αENaC contributes to vascular endothelial function in vivo

DEFF Research Database (Denmark)

Tarjus, Antoine; Maase, Martina; Jeggle, Pia

2017-01-01

The Epithelial Sodium Channel (ENaC) is a key player in renal sodium homeostasis. The expression of α β γ ENaC subunits has also been described in the endothelium and vascular smooth muscle, suggesting a role in vascular function. We recently demonstrated that endothelial ENaC is involved in aldo......-mediated dilation. Our data suggest that endothelial αENaC contributes to vascular endothelial function in vivo....

The KATP channel in migraine pathophysiology

DEFF Research Database (Denmark)

Al-Karagholi, Mohammad Al-Mahdi; Hansen, Jakob Møller; Severinsen, Johanne

2017-01-01

BACKGROUND: To review the distribution and function of KATP channels, describe the use of KATP channels openers in clinical trials and make the case that these channels may play a role in headache and migraine. DISCUSSION: KATP channels are widely present in the trigeminovascular system and play...... an important role in the regulation of tone in cerebral and meningeal arteries. Clinical trials using synthetic KATP channel openers report headache as a prevalent-side effect in non-migraine sufferers, indicating that KATP channel opening may cause headache, possibly due to vascular mechanisms. Whether KATP...... channel openers can provoke migraine in migraine sufferers is not known. CONCLUSION: We suggest that KATP channels may play an important role in migraine pathogenesis and could be a potential novel therapeutic anti-migraine target....

ACTIVITIES RESULTS AIMED AT IMPROVED MEDICAL ASSISTANCE TO THE VASCULAR PATIENTS IN TOMSK REGION

Directory of Open Access Journals (Sweden)

D. M. Plotnikov

2013-01-01

Full Text Available Acute disorders of cerebral circulation remain serious medical and social problem associated with high disability and mortality rates. Since 2011 Tomsk oblast is a participating member of the medical campaign aimed at improved medical services to the vascular patients. The preliminary implementation data analysis for 2012 revealed improvement of most of the indices of medical support to patients suffering from acute cerebral circulation; increased number of the in-patient cases (Regional Vascular Center and primary vascular department, decreased lethality rates from strokes, specifically hemorrhagic cases. Strict observance of the Regulations on Medical Assistance for stroke patients and the using of modern methods of therapy allowed to decrease hospital mortality in the Primary Vascular Departments and early mortality in the Regional Vascular Center. The active implementation of neurorehabilitation approaches resulted in the increased number of patients who do not require third parties’ assistance. Analysis of the work of the departments helped to identifying current problems and perspectives of further development of special medical care for stroke patients.

Functional and pharmacological consequences of the distribution of voltage-gated calcium channels in the renal blood vessels.

Science.gov (United States)

Hansen, P B L

2013-04-01

Calcium channel blockers are widely used to treat hypertension because they inhibit voltage-gated calcium channels that mediate transmembrane calcium influx in, for example, vascular smooth muscle and cardiomyocytes. The calcium channel family consists of several subfamilies, of which the L-type is usually associated with vascular contractility. However, the L-, T- and P-/Q-types of calcium channels are present in the renal vasculature and are differentially involved in controlling vascular contractility, thereby contributing to regulation of kidney function and blood pressure. In the preglomerular vascular bed, all the three channel families are present. However, the T-type channel is the only channel in cortical efferent arterioles which is in contrast to the juxtamedullary efferent arteriole, and that leads to diverse functional effects of L- and T-type channel inhibition. Furthermore, by different mechanisms, T-type channels may contribute to both constriction and dilation of the arterioles. Finally, P-/Q-type channels are involved in the regulation of human intrarenal arterial contractility. The calcium blockers used in the clinic affect not only L-type but also P-/Q- and T-type channels. Therefore, the distinct effect obtained by inhibiting a given subtype or set of channels under experimental settings should be considered when choosing a calcium blocker for treatment. T-type channels seem to be crucial for regulating the GFR and the filtration fraction. Use of blockers is expected to lead to preferential efferent vasodilation, reduction of glomerular pressure and proteinuria. Therefore, renovascular T-type channels might provide novel therapeutic targets, and may have superior renoprotective effects compared to conventional calcium blockers. Acta Physiologica © 2013 Scandinavian Physiological Society.

Novel asymptotic results on the high-order statistics of the channel capacity over generalized fading channels

KAUST Repository

Yilmaz, Ferkan

2012-06-01

The exact analysis of the higher-order statistics of the channel capacity (i.e., higher-order ergodic capacity) often leads to complicated expressions involving advanced special functions. In this paper, we provide a generic framework for the computation of the higher-order statistics of the channel capacity over generalized fading channels. As such, this novel framework for the higher-order statistics results in simple, closed-form expressions which are shown to be asymptotically tight bounds in the high signal-to-noise ratio (SNR) regime of a variety of fading environment. In addition, it reveals the existence of differences (i.e., constant capacity gaps in log-domain) among different fading environments. By asymptotically tight bound we mean that the high SNR limit of the difference between the actual higher-order statistics of the channel capacity and its asymptotic bound (i.e., lower bound) tends to zero. The mathematical formalism is illustrated with some selected numerical examples that validate the correctness of our newly derived results. © 2012 IEEE.

Coronary arterial BK channel dysfunction exacerbates ischemia/reperfusion-induced myocardial injury in diabetic mice.

Science.gov (United States)

Lu, Tong; Jiang, Bin; Wang, Xiao-Li; Lee, Hon-Chi

2016-09-01

The large conductance Ca(2+)-activated K(+) (BK) channels, abundantly expressed in coronary artery smooth muscle cells (SMCs), play a pivotal role in regulating coronary circulation. A large body of evidence indicates that coronary arterial BK channel function is diminished in both type 1 and type 2 diabetes. However, the consequence of coronary BK channel dysfunction in diabetes is not clear. We hypothesized that impaired coronary BK channel function exacerbates myocardial ischemia/reperfusion (I/R) injury in streptozotocin-induced diabetic mice. Combining patch-clamp techniques and cellular biological approaches, we found that diabetes facilitated the colocalization of angiotensin II (Ang II) type 1 receptors and BK channel α-subunits (BK-α), but not BK channel β1-subunits (BK-β1), in the caveolae of coronary SMCs. This caveolar compartmentation in vascular SMCs not only enhanced Ang II-mediated inhibition of BK-α but also produced a physical disassociation between BK-α and BK-β1, leading to increased infarct size in diabetic hearts. Most importantly, genetic ablation of caveolae integrity or pharmacological activation of coronary BK channels protected the cardiac function of diabetic mice from experimental I/R injury in both in vivo and ex vivo preparations. Our results demonstrate a vascular ionic mechanism underlying the poor outcome of myocardial injury in diabetes. Hence, activation of coronary BK channels may serve as a therapeutic target for cardiovascular complications of diabetes.

T-type Ca(2+) channels and Autoregulation of Local Blood Flow

DEFF Research Database (Denmark)

Jensen, Lars Jørn; Nielsen, Morten Schak; Salomonsson, Max

2017-01-01

L-type voltage gated Ca(2+) channels are considered to be the primary source of calcium influx during the myogenic response. However, many vascular beds also express T-type voltage gated Ca(2+) channels. Recent studies suggest that these channels may also play a role in autoregulation. At low pre...

Nitric oxide signaling and the cross talk with prostanoids pathways in vascular system.

Science.gov (United States)

Silva, Bruno R; Paula, Tiago D; Paulo, Michele; Bendhack, Lusiane M

2016-12-28

This review provides an overview of the cellular signaling of nitric oxide (NO) and prostanoids in vascular cells and the possible cross talk between their pathways, mainly in hypertension, since the imbalance of these two systems has been attributed to development of some cardiovascular diseases. It also deals with the modulation of vasodilation induced by NO donors. NO is a well-known second messenger involved in many cellular functions. In the vascular system, the NO produced by endothelial NO-synthase (eNOS) or released by NO donors acts in vascular smooth muscle cells, the binding of NO to Fe2+-heme of soluble guanylyl-cyclase (sGC) activates sGC and the production of cyclic guanosine-3-5-monophosphate (cGMP). The second messenger (cGMP) activates protein kinase G and the signaling cascade, including K+ channels. Activation of K+ channels leads to cell membrane hyperpolarization and Ca2+ channels blockade, which induce vascular relaxation. Moreover, the enzyme cyclooxygenase (COX) is also an important regulator of the vascular function by prostanoids production such as thromboxane A2 (TXA2) and prostacyclin (PGI2), which classically induce contraction and relaxation, respectively. Additionaly, studies indicate that the activity of both enzymes can be modulated by their products and reactive oxygen species (ROS) in cardiovascular diseases such as hypertension. The interaction of NO with cellular molecules, particularly the reaction of NO with ROS, determines the biological mechanisms of action and short half-life of NO. We have been working on the vascular effects of ruthenium-derived complexes that release NO. Our research group has published works on the vasodilating effects of ruthenium-derived NO donors and the mechanisms of vascular cells involved in the relaxation of the vascular smooth muscle in health and hypertensive rats. In our previous studies, we have compared the new NO donors synthesized by our group to SNP. It shows the cellular signaling of NO

Aluminum exposure for one hour decreases vascular reactivity in conductance and resistance arteries in rats

International Nuclear Information System (INIS)

Schmidt, Patrícia Medeiros; Escobar, Alyne Goulart; Torres, João Guilherme Dini; Martinez, Caroline Silveira; Rizzetti, Danize Aparecida; Kunz, Simone Noremberg; Vassallo, Dalton Valentim; Alonso, María Jesús; Peçanha, Franck Maciel; Wiggers, Giulia Alessandra

2016-01-01

Aims: Aluminum (Al) is an important environmental contaminant; however, there are not enough evidences of Al-induced cardiovascular dysfunction. We investigated the effects of acute exposure to aluminum chloride (AlCl 3 ) on blood pressure, vascular reactivity and oxidative stress. Methods and results: Male Wistar rats were divided into two groups: Untreated: vehicle (ultrapure water, ip) and AlCl 3 : single dose of AlCl 3 (100 mg/kg,ip). Concentration-response curves to phenylephrine in the absence and presence of endothelium, the nitric oxide synthase inhibitor L-NAME, the potassium channel blocker tetraethylammonium, and the NADPH oxidase inhibitor apocynin were performed in segments from aortic and mesenteric resistance arteries. NO released was assessed in aorta and reactive oxygen species (ROS), malondialdehyde, non-protein thiol levels, antioxidant capacity and enzymatic antioxidant activities were investigated in plasma, aorta and/or mesenteric arteries. After one hour of AlCl 3 exposure serum Al levels attained 147.7 ± 25.0 μg/L. Al treatment: 1) did not affect blood pressure, heart rate and vasodilator responses induced by acetylcholine or sodium nitroprusside; 2) decreased phenylephrine-induced vasoconstrictor responses; 3) increased endothelial modulation of contractile responses, NO release and vascular ROS production from NADPH oxidase; 4) increased plasmatic, aortic and mesenteric malondialdehyde and ROS production, and 5) decreased antioxidant capacity and affected the antioxidant biomarkers non-protein thiol levels, glutathione peroxidase, glutathione-S-transferase, superoxide dismutase and catalase enzymatic activities. Conclusion: AlCl 3 -acute exposure reduces vascular reactivity. This effect is associated with increased NO production, probably acting on K + channels, which seems to occur as a compensatory mechanism against Al-induced oxidative stress. Our results suggest that Al exerts toxic effects to the vascular system. - Highlights: �

Aluminum exposure for one hour decreases vascular reactivity in conductance and resistance arteries in rats

Energy Technology Data Exchange (ETDEWEB)

Schmidt, Patrícia Medeiros; Escobar, Alyne Goulart; Torres, João Guilherme Dini; Martinez, Caroline Silveira; Rizzetti, Danize Aparecida; Kunz, Simone Noremberg [Postgraduate Program in Biochemistry, Universidade Federal do Pampa, Uruguaiana, Rio Grande do Sul (Brazil); Vassallo, Dalton Valentim [Department of Physiological Sciences, Universidade Federal do Espírito Santo, Espirito Santo (Brazil); Alonso, María Jesús [Department of Basic Health Sciences, Universidad Rey Juan Carlos, Alcorcón (Spain); Peçanha, Franck Maciel [Postgraduate Program in Biochemistry, Universidade Federal do Pampa, Uruguaiana, Rio Grande do Sul (Brazil); Wiggers, Giulia Alessandra, E-mail: giuliawp@gmail.com [Postgraduate Program in Biochemistry, Universidade Federal do Pampa, Uruguaiana, Rio Grande do Sul (Brazil)

2016-12-15

Aims: Aluminum (Al) is an important environmental contaminant; however, there are not enough evidences of Al-induced cardiovascular dysfunction. We investigated the effects of acute exposure to aluminum chloride (AlCl{sub 3}) on blood pressure, vascular reactivity and oxidative stress. Methods and results: Male Wistar rats were divided into two groups: Untreated: vehicle (ultrapure water, ip) and AlCl{sub 3}: single dose of AlCl{sub 3} (100 mg/kg,ip). Concentration-response curves to phenylephrine in the absence and presence of endothelium, the nitric oxide synthase inhibitor L-NAME, the potassium channel blocker tetraethylammonium, and the NADPH oxidase inhibitor apocynin were performed in segments from aortic and mesenteric resistance arteries. NO released was assessed in aorta and reactive oxygen species (ROS), malondialdehyde, non-protein thiol levels, antioxidant capacity and enzymatic antioxidant activities were investigated in plasma, aorta and/or mesenteric arteries. After one hour of AlCl{sub 3} exposure serum Al levels attained 147.7 ± 25.0 μg/L. Al treatment: 1) did not affect blood pressure, heart rate and vasodilator responses induced by acetylcholine or sodium nitroprusside; 2) decreased phenylephrine-induced vasoconstrictor responses; 3) increased endothelial modulation of contractile responses, NO release and vascular ROS production from NADPH oxidase; 4) increased plasmatic, aortic and mesenteric malondialdehyde and ROS production, and 5) decreased antioxidant capacity and affected the antioxidant biomarkers non-protein thiol levels, glutathione peroxidase, glutathione-S-transferase, superoxide dismutase and catalase enzymatic activities. Conclusion: AlCl{sub 3}-acute exposure reduces vascular reactivity. This effect is associated with increased NO production, probably acting on K{sup +} channels, which seems to occur as a compensatory mechanism against Al-induced oxidative stress. Our results suggest that Al exerts toxic effects to the vascular

Angiotensin Converting-Enzyme Inhibitors, Angiotensin Receptor Blockers, and Calcium Channel Blockers Are Associated with Prolonged Vascular Access Patency in Uremic Patients Undergoing Hemodialysis.

Directory of Open Access Journals (Sweden)

Fu-An Chen

Full Text Available Vascular access failure is a huge burden for patients undergoing hemodialysis. Many efforts have been made to maintain vascular access patency, including pharmacotherapy. Angiotensin converting enzyme inhibitor (ACE-I, angiotensin receptor blocker (ARB, and calcium channel blocker (CCB are known for their antihypertensive and cardio-protective effects, however, their effects on long-term vascular access patency are still inconclusive.We retrospectively enrolled patients commencing maintenance hemodialysis between January 1, 2000, and December 31, 2006 by using National Health Insurance Research Database in Taiwan. Primary patency was defined as the date of first arteriovenous fistula (AVF or arteriovenous graft (AVG creation to the time of access thrombosis or any intervention aimed to maintain or re-establish vascular access patency. Cox proportional hazards models were used to adjust the influences of patient characteristics, co-morbidities and medications.Total 42244 patients were enrolled in this study, 37771 (89.4% used AVF, 4473 (10.6% used AVG as their first long term dialysis access. ACE-I, ARB, and CCB use were all associated with prolonged primary patency of AVF [hazard ratio (HR 0.586, 95% confidence interval (CI 0.557-0.616 for ACE-I use; HR 0.532, CI 0.508-0.556 for ARB use; HR 0.485, CI 0.470-0.501 for CCB use] and AVG (HR 0.557, CI 0.482-0.643 for ACE-I use, HR 0.536, CI 0.467-0.614 for ARB use, HR 0.482, CI 0.442-0.526 for CCB use.In our analysis, ACE-I, ARB, and CCB were strongly associated with prolonged primary patency of both AVF and AVG. Further prospective randomized studies are still warranted to prove the causality.

Renovascular BK(Ca) channels are not activated in vivo under resting conditions and during agonist stimulation

DEFF Research Database (Denmark)

Magnusson, Linda; Sørensen, Charlotte Mehlin; Braunstein, Thomas Hartig

2006-01-01

We investigated the role of large-conductance Ca(2+)-activated K(+) (BK(Ca)) channels for the basal renal vascular tone in vivo. Furthermore, the possible buffering by BK(Ca) of the vasoconstriction elicited by angiotensin II (ANG II) or norepinephrine (NE) was investigated. The possible activation.......3 nmol/min) did not have any effect. Renal injection of ANG II (1-4 ng) or NE (10-40 ng) produced a transient decrease in RBF. These responses were not affected by preinfusion of TEA or IBT. Renal infusion of the BK(Ca) opener NS-1619 (90.0 nmol/min) did not affect basal RBF or the response to NE......, there is no indication for a major role for BK(Ca) channels in the control of basal renal tone in vivo. Furthermore, BK(Ca) channels do not have a buffering effect on the rat renal vascular responses to ANG II and NE. The fact that NS-1619 attenuates the ANG II response indicates that the renal vascular BK(Ca) channels...

Fundamental Limits of Parallel Optical Wireless Channels: Capacity Results and Outage Formulation

KAUST Repository

Chaaban, Anas; Rezki, Zouheir; Alouini, Mohamed-Slim

2016-01-01

Multi-channel (MC) optical wireless communication (OWC) systems employing wave-division multiplexing for outdoors free-space optical communications, or multi-user timedivision multiple access for indoors visible-light communications, e.g., can be modeled as parallel channels. Multi-input multioutput OWC systems can also be transformed, possibly with some performance loss, to parallel channels using pre-/postcoding. Studying the performance of such MC-OWC systems requires characterizing the capacity of the underlying parallel channels. In this paper, upper and lower bounds on the capacity of constant parallel OWC channels with a total average intensity constraint are derived. Then, the paper focuses on finding intensity allocations that maximize the lower bounds given channel-state information at the transmitter (CSIT). Due to its nonconvexity, the KKT conditions are used to describe a list of candidate allocations. Instead searching exhaustively for the best solution, low-complexity near-optimal algorithms are proposed. The resulting optimized lower bound nearly coincides with capacity at high signal-to-noise ratio (SNR). Under a quasi-static channel model and in the absence of CSIT, outage probability upper and lower bounds are derived. Those bounds also meet at high SNR, thus characterizing the outage capacity in this regime. Finally, the results are extended to a system with both average and peak intensity constraints.

Fundamental Limits of Parallel Optical Wireless Channels: Capacity Results and Outage Formulation

KAUST Repository

Chaaban, Anas

2016-10-26

Multi-channel (MC) optical wireless communication (OWC) systems employing wave-division multiplexing for outdoors free-space optical communications, or multi-user timedivision multiple access for indoors visible-light communications, e.g., can be modeled as parallel channels. Multi-input multioutput OWC systems can also be transformed, possibly with some performance loss, to parallel channels using pre-/postcoding. Studying the performance of such MC-OWC systems requires characterizing the capacity of the underlying parallel channels. In this paper, upper and lower bounds on the capacity of constant parallel OWC channels with a total average intensity constraint are derived. Then, the paper focuses on finding intensity allocations that maximize the lower bounds given channel-state information at the transmitter (CSIT). Due to its nonconvexity, the KKT conditions are used to describe a list of candidate allocations. Instead searching exhaustively for the best solution, low-complexity near-optimal algorithms are proposed. The resulting optimized lower bound nearly coincides with capacity at high signal-to-noise ratio (SNR). Under a quasi-static channel model and in the absence of CSIT, outage probability upper and lower bounds are derived. Those bounds also meet at high SNR, thus characterizing the outage capacity in this regime. Finally, the results are extended to a system with both average and peak intensity constraints.

Interventional C-arm tomosynthesis for vascular imaging: initial results

Science.gov (United States)

Langan, David A.; Claus, Bernhard E. H.; Al Assad, Omar; Trousset, Yves; Riddell, Cyril; Avignon, Gregoire; Solomon, Stephen B.; Lai, Hao; Wang, Xin

2015-03-01

As percutaneous endovascular procedures address more complex and broader disease states, there is an increasing need for intra-procedure 3D vascular imaging. In this paper, we investigate C-Arm 2-axis tomosynthesis ("Tomo") as an alternative to C-Arm Cone Beam Computed Tomography (CBCT) for workflow situations in which the CBCT acquisition may be inconvenient or prohibited. We report on our experience in performing tomosynthesis acquisitions with a digital angiographic imaging system (GE Healthcare Innova 4100 Angiographic Imaging System, Milwaukee, WI). During a tomo acquisition the detector and tube each orbit on a plane above and below the table respectively. The tomo orbit may be circular or elliptical, and the tomographic half-angle in our studies varied from approximately 16 to 28 degrees as a function of orbit period. The trajectory, geometric calibration, and gantry performance are presented. We overview a multi-resolution iterative reconstruction employing compressed sensing techniques to mitigate artifacts associated with incomplete data reconstructions. In this work, we focus on the reconstruction of small high contrast objects such as iodinated vasculature and interventional devices. We evaluate the overall performance of the acquisition and reconstruction through phantom acquisitions and a swine study. Both tomo and comparable CBCT acquisitions were performed during the swine study thereby enabling the use of CBCT as a reference in the evaluation of tomo vascular imaging. We close with a discussion of potential clinical applications for tomo, reflecting on the imaging and workflow results achieved.

Shaker-related voltage-gated K+ channel expression and vasomotor function in human coronary resistance arteries.

Science.gov (United States)

Nishijima, Yoshinori; Korishettar, Ankush; Chabowski, Dawid S; Cao, Sheng; Zheng, Xiaodong; Gutterman, David D; Zhang, David X

2018-01-01

K V channels are important regulators of vascular tone, but the identity of specific K V channels involved and their regulation in disease remain less well understood. We determined the expression of K V 1 channel subunits and their role in cAMP-mediated dilation in coronary resistance arteries from subjects with and without CAD. HCAs from patients with and without CAD were assessed for mRNA and protein expression of K V 1 channel subunits with molecular techniques and for vasodilator response with isolated arterial myography. Assays of mRNA transcripts, membrane protein expression, and vascular cell-specific localization revealed abundant expression of K V 1.5 in vascular smooth muscle cells of non-CAD HCAs. Isoproterenol and forskolin, two distinct cAMP-mediated vasodilators, induced potent dilation of non-CAD arterioles, which was inhibited by both the general K V blocker 4-AP and the selective K V 1.5 blocker DPO-1. The cAMP-mediated dilation was reduced in CAD and was accompanied by a loss of or reduced contribution of 4-AP-sensitive K V channels. K V 1.5, as a major 4-AP-sensitive K V 1 channel expressed in coronary VSMCs, mediates cAMP-mediated dilation in non-CAD arterioles. The cAMP-mediated dilation is reduced in CAD coronary arterioles, which is associated with impaired 4-AP-sensitive K V channel function. © 2017 John Wiley & Sons Ltd.

Protein Kinase C Inhibitors as Modulators of Vascular Function and Their Application in Vascular Disease

Directory of Open Access Journals (Sweden)

Raouf A. Khalil

2013-03-01

Full Text Available Blood pressure (BP is regulated by multiple neuronal, hormonal, renal and vascular control mechanisms. Changes in signaling mechanisms in the endothelium, vascular smooth muscle (VSM and extracellular matrix cause alterations in vascular tone and blood vessel remodeling and may lead to persistent increases in vascular resistance and hypertension (HTN. In VSM, activation of surface receptors by vasoconstrictor stimuli causes an increase in intracellular free Ca2+ concentration ([Ca2+]i, which forms a complex with calmodulin, activates myosin light chain (MLC kinase and leads to MLC phosphorylation, actin-myosin interaction and VSM contraction. Vasoconstrictor agonists could also increase the production of diacylglycerol which activates protein kinase C (PKC. PKC is a family of Ca2+-dependent and Ca2+-independent isozymes that have different distributions in various blood vessels, and undergo translocation from the cytosol to the plasma membrane, cytoskeleton or the nucleus during cell activation. In VSM, PKC translocation to the cell surface may trigger a cascade of biochemical events leading to activation of mitogen-activated protein kinase (MAPK and MAPK kinase (MEK, a pathway that ultimately increases the myofilament force sensitivity to [Ca2+]i, and enhances actin-myosin interaction and VSM contraction. PKC translocation to the nucleus may induce transactivation of various genes and promote VSM growth and proliferation. PKC could also affect endothelium-derived relaxing and contracting factors as well as matrix metalloproteinases (MMPs in the extracellular matrix further affecting vascular reactivity and remodeling. In addition to vasoactive factors, reactive oxygen species, inflammatory cytokines and other metabolic factors could affect PKC activity. Increased PKC expression and activity have been observed in vascular disease and in certain forms of experimental and human HTN. Targeting of vascular PKC using PKC inhibitors may function in

Mechanisms of cellular synchronization in the vascular wall. Mechanisms of vasomotion.

Science.gov (United States)

Matchkov, Vladimir V

2010-10-01

Although the function of rhythmic contractions in the vascular wall - vasomotion - is still under debate, it has been suggested to play a significant role for tissue oxygen homeostasis and under pathological conditions where tissue perfusion is affected. Vasomotion has further been suggested to be important for blood pressure control and has been shown to be reduced in diabetes. Vasomotion is initiated by the coordinated activation of smooth muscle cells (SMCs) in the vascular wall leading to rhythmic contractions. We have suggested the model for generation of this rhythmic activity and have shown that vasomotion initiates via interaction between intracellular calcium released from the sarcoplasmic reticulum and changes in membrane potential. Rhythmic changes in intracellular calcium induce, under certain conditions (in the presence of sufficient concentration of cGMP), changes in membrane potential that lock the electrically-connected SMCs into phase. Synchronized depolarization induces synchronous calcium influx and thus produces rhythmic contraction of blood vessels. I have demonstrated and characterized a new chloride channel in vascular SMCs, which has properties necessary to coordinate SMCs in the vascular wall. Chloride channels have been investigated for many years but remained somewhat in the shadow of cation channels. We know now the molecular structures of some chloride channels, i.e. GABA receptors, "cystic fibrosis transmem-brane conductance regulator" (CFTR) and the ClC chloride channel family. There is one particular group of chloride channels, the calcium activated chloride channels (CaCCs), whose molecular structure is debated still. There are currently no pharmacological tools that activate or inhibit CaCCs with any significant selectivity. The existence of CaCCs in almost all cells in the body has been known for many years based on electrophysiological and other functional studies. CaCCs have been suggested to be important for regulation of

Strain-free polished channel-cut crystal monochromators: a new approach and results

Science.gov (United States)

Kasman, Elina; Montgomery, Jonathan; Huang, XianRong; Lerch, Jason; Assoufid, Lahsen

2017-08-01

The use of channel-cut crystal monochromators has been traditionally limited to applications that can tolerate the rough surface quality from wet etching without polishing. We have previously presented and discussed the motivation for producing channel cut crystals with strain-free polished surfaces [1]. Afterwards, we have undertaken an effort to design and implement an automated machine for polishing channel-cut crystals. The initial effort led to inefficient results. Since then, we conceptualized, designed, and implemented a new version of the channel-cut polishing machine, now called C-CHiRP (Channel-Cut High Resolution Polisher), also known as CCPM V2.0. The new machine design no longer utilizes Figure-8 motion that mimics manual polishing. Instead, the polishing is achieved by a combination of rotary and linear functions of two coordinated motion systems. Here we present the new design of C-CHiRP, its capabilities and features. Multiple channel-cut crystals polished using the C-CHiRP have been deployed into several beamlines at the Advanced Photon Source (APS). We present the measurements of surface finish, flatness, as well as topography results obtained at 1-BM of APS, as compared with results typically achieved when polishing flat-surface monochromator crystals using conventional polishing processes. Limitations of the current machine design, capabilities and considerations for strain-free polishing of highly complex crystals are also discussed, together with an outlook for future developments and improvements.

Influence of vascular network design on gas transfer in lung assist device technology.

Science.gov (United States)

Bassett, Erik K; Hoganson, David M; Lo, Justin H; Penson, Elliot J N; Vacanti, Joseph P

2011-01-01

Blood oxygenators are vital for the critically ill, but their use is limited to the hospital setting. A portable blood oxygenator or a lung assist device for ambulatory or long-term use would greatly benefit patients with chronic lung disease. In this work, a biomimetic blood oxygenator system was developed which consisted of a microfluidic vascular network covered by a gas permeable silicone membrane. This system was used to determine the influence of key microfluidic parameters-channel size, oxygen exposure length, and blood shear rate-on blood oxygenation and carbon dioxide removal. Total gas transfer increased linearly with flow rate, independent of channel size and oxygen exposure length. On average, CO(2) transfer was 4.3 times higher than oxygen transfer. Blood oxygen saturation was also found to depend on the flow rate per channel but in an inverse manner; oxygenation decreased and approached an asymptote as the flow rate per channel increased. These relationships can be used to optimize future biomimetic vascular networks for specific lung applications: gas transfer for carbon dioxide removal in patients with chronic obstructive pulmonary disease or oxygenation for premature infants requiring complete lung replacement therapy.

Episodic vertigo resulting from vascular risk factors, cervical spondylosis and head rotation: Two case reports.

Science.gov (United States)

Owolabi, Mayowa O; Ogah, Okechukwu S; Ogunniyi, Adesola

2007-01-01

Vascular risk factors predispose to vertebrobasilar ischemia. Cervical osteophytes can impinge on the vertebral artery causing mechanical occlusion during head turning. Presentation with vertigo in such instances is a common finding. A patient with obesity, hyperlipidemia, hypertension, cervical spondylosis, and vertigo triggered by head rotation is presented. She responded to antihypertensive and lipid-lowering drugs, vestibular sedative and application of cervical collar. The second patient also exhibited similar features and responded to conservative treatment. Rotational vertebral artery occlusion resulting from cervical spondylosis in the presence of atherosclerosed collateral vessels is a cause of posterior circulation insufficiency manifesting as vertigo. The tetrad of vertigo resulting from vascular risk factors, cervical spondylosis, and head rotation is proposed for further research.

Diclofenac distinguishes among homomeric and heteromeric potassium channels composed of KCNQ4 and KCNQ5 subunits.

Science.gov (United States)

Brueggemann, Lioubov I; Mackie, Alexander R; Martin, Jody L; Cribbs, Leanne L; Byron, Kenneth L

2011-01-01

KCNQ4 and KCNQ5 potassium channel subunits are expressed in vascular smooth muscle cells, although it remains uncertain how these subunits assemble to form functional channels. Using patch-clamp techniques, we compared the electrophysiological characteristics and effects of diclofenac, a known KCNQ channel activator, on human KCNQ4 and KCNQ5 channels expressed individually or together in A7r5 rat aortic smooth muscle cells. The conductance curves of the overexpressed channels were fitted by a single Boltzmann function in each case (V(0.5) values: -31, -44, and -38 mV for KCNQ4, KCNQ5, and KCNQ4/5, respectively). Diclofenac (100 μM) inhibited KCNQ5 channels, reducing maximum conductance by 53%, but increased maximum conductance of KCNQ4 channels by 38%. The opposite effects of diclofenac on KCNQ4 and KCNQ5 could not be attributed to the presence of a basic residue (lysine) in the voltage-sensing domain of KCNQ5, because mutation of this residue to neutral glycine (the residue present in KCNQ4) resulted in a more effective block of the channel. Differences in deactivation rates and distinct voltage-dependent effects of diclofenac on channel activation and deactivation observed with each of the subunit combinations (KCNQ4, KCNQ5, and KCNQ4/5) were used as diagnostic tools to evaluate native KCNQ currents in vascular smooth muscle cells. A7r5 cells express only KCNQ5 channels endogenously, and their responses to diclofenac closely resembled those of the overexpressed KCNQ5 currents. In contrast, mesenteric artery myocytes, which express both KCNQ4 and KCNQ5 channels, displayed whole-cell KCNQ currents with properties and diclofenac responses characteristic of overexpressed heteromeric KCNQ4/5 channels.

Vascular smooth muscle cells express the alpha(1A) subunit of a P-/Q-type voltage-dependent Ca(2+)Channel, and It is functionally important in renal afferent arterioles

DEFF Research Database (Denmark)

Hansen, Pernille B. Lærkegaard; Jensen, Boye L.; Andreasen, D

2000-01-01

In the present study, we tested whether the alpha(1A) subunit, which encodes a neuronal isoform of voltage-dependent Ca(2+) channels (VDCCs) (P-/Q-type), was present and functional in vascular smooth muscle and renal resistance vessels. By reverse transcription-polymerase chain reaction...... preglomerular resistance vessels and aorta, as well as mesangial cells, and that P-type VDCCs contribute to Ca(2+) influx in aortic and renal VSMCs and are involved in depolarization-mediated contraction in renal afferent arterioles....

Endothelial Small- and Intermediate-Conductance KCa Channels

DEFF Research Database (Denmark)

Wulff, Heike; Köhler, Ralf

2013-01-01

ABSTRACT:: Most cardiovascular researchers are familiar with intermediate-conductance KCa3.1 and small-conductance KCa2.3 channels because of their contribution to endothelium-derived hyperpolarization (EDH). However, to immunologists and neuroscientists these channels are primarily known...... for their role in lymphocyte activation and neuronal excitability. KCa3.1 is involved in the proliferation and migration of T cells, B cell, mast cells, macrophages, fibroblasts and dedifferentiated vascular smooth muscle cells and is, therefore, being pursued as a potential target for use in asthma...

Novel Compound-Forming Technology Using Bioprinting and Electrospinning for Patterning a 3D Scaffold Construct with Multiscale Channels

Directory of Open Access Journals (Sweden)

Yuanshao Sun

2016-12-01

Full Text Available One of the biggest challenges for tissue engineering is to efficiently provide oxygen and nutrients to cells on a three-dimensional (3D engineered scaffold structure. Thus, achieving sufficient vascularization of the structure is a critical problem in tissue engineering. This facilitates the need to develop novel methods to enhance vascularization. Use of patterned hydrogel structures with multiscale channels can be used to achieve the required vascularization. Patterned structures need to be biocompatible and biodegradable. In this study, gelatin was used as the main part of a hydrogel to prepare a biological structure with 3D multiscale channels using bioprinting combined with selection of suitable materials and electrostatic spinning. Human umbilical vein endothelial cells (HUVECs were then used to confirm efficacy of the structure, inferred from cell viability on different engineered construct designs. HUVECs were seeded on the surface of channels and cultured in vitro. HUVECs showed high viability and diffusion within the construct. This method can be used as a practical platform for the fabrication of engineered construct for vascularization.

Lymphangioma circumscriptum, angiokeratoma, or superficial vascular ectasia with epithelial hyperplasia?

Science.gov (United States)

Katsoulas, Nikolaos; Tosios, Konstantinos I; Argyris, Prokopios; Koutlas, Ioannis G; Sklavounou, Alexandra

2014-08-01

We report a case of lymphangioma circumscriptum (cavernous lymphangioma with epithelial hyperplasia) in a 12-year-old girl, presenting as a papillary tumor on the right dorsal side of her tongue. Microscopic examination found cavernous vascular channels lined by a single layer of CD31(+), podoplanin-positive, CD34(-) endothelial cells that occupied the papillary lamina propria and were accompanied by epithelial hyperplasia. A review of the literature on oral vascular tumors with epithelial hyperplasia, namely, lymphangioma circumscriptum and angiokeratoma, provided information that draws into question the use of these terms. Copyright © 2014 Elsevier Inc. All rights reserved.

The secret life of ion channels: Kv1.3 potassium channels and proliferation.

Science.gov (United States)

Pérez-García, M Teresa; Cidad, Pilar; López-López, José R

2018-01-01

Kv1.3 channels are involved in the switch to proliferation of normally quiescent cells, being implicated in the control of cell cycle in many different cell types and in many different ways. They modulate membrane potential controlling K + fluxes, sense changes in potential, and interact with many signaling molecules through their intracellular domains. From a mechanistic point of view, we can describe the role of Kv1.3 channels in proliferation with at least three different models. In the "membrane potential model," membrane hyperpolarization resulting from Kv1.3 activation provides the driving force for Ca 2+ influx required to activate Ca 2+ -dependent transcription. This model explains most of the data obtained from several cells from the immune system. In the "voltage sensor model," Kv1.3 channels serve mainly as sensors that transduce electrical signals into biochemical cascades, independently of their effect on membrane potential. Kv1.3-dependent proliferation of vascular smooth muscle cells (VSMCs) could fit this model. Finally, in the "channelosome balance model," the master switch determining proliferation may be related to the control of the Kv1.3 to Kv1.5 ratio, as described in glial cells and also in VSMCs. Since the three mechanisms cannot function independently, these models are obviously not exclusive. Nevertheless, they could be exploited differentially in different cells and tissues. This large functional flexibility of Kv1.3 channels surely gives a new perspective on their functions beyond their elementary role as ion channels, although a conclusive picture of the mechanisms involved in Kv1.3 signaling to proliferation is yet to be reached.

Pacinian channel mediated vasoconstriction in the fingers during vibration exposure

OpenAIRE

Ye, Ying

2013-01-01

A review of the literature showed that acute vascular responses to hand-transmitted vibration depend on the magnitude, the frequency, and the duration of the vibration but the mechanisms involved in the immediate vasoconstriction on exposure to vibration are not clear. This research was designed to advance understanding of the relation between the characteristics of vibration and changes in vascular circulation on exposed hands, and to develop a model of the mechanoreceptor channel involved i...

Physiology and pathophysiology of K(ATP) channels in the pancreas and cardiovascular system: a review.

Science.gov (United States)

Seino, Susumu

2003-01-01

K(ATP) channels are present in pancreatic and extrapancreatic tissues such as heart and smooth muscle, and display diverse molecular composition. They contain two different structural subunits: an inwardly rectifying potassium channel subunit (Kir6.x) and a sulfonylurea receptor (SURX). Recent studies on genetically engineered Kir6.2 knockout mice have provided a better understanding of the physiological and pathophysiological roles of Kir6.2-containing K(ATP) channels. Kir6.2/SUR1 has a pivotal role in pancreatic insulin secretion. Kir6.2/SUR2A mediates the effects of K(ATP) channels openers on cardiac excitability and contractility and contributes to ischemic preconditioning. However, controversy remains on the physiological properties of the K(ATP) channels in vascular smooth muscle cells. Kir6.1 knockout mice exhibit sudden cardiac death due to cardiac ischemia, indicating that Kir6.1 rather than Kir6.2 is critical in the regulation of vascular tone. This article summarizes current understanding of the physiology and pathophysiology of Kir6.1- and Kir6.2-containing K(ATP) channels.

Diclofenac Distinguishes among Homomeric and Heteromeric Potassium Channels Composed of KCNQ4 and KCNQ5 SubunitsS⃞

Science.gov (United States)

Brueggemann, Lioubov I.; Mackie, Alexander R.; Martin, Jody L.; Cribbs, Leanne L.

2011-01-01

KCNQ4 and KCNQ5 potassium channel subunits are expressed in vascular smooth muscle cells, although it remains uncertain how these subunits assemble to form functional channels. Using patch-clamp techniques, we compared the electrophysiological characteristics and effects of diclofenac, a known KCNQ channel activator, on human KCNQ4 and KCNQ5 channels expressed individually or together in A7r5 rat aortic smooth muscle cells. The conductance curves of the overexpressed channels were fitted by a single Boltzmann function in each case (V0.5 values: −31, −44, and −38 mV for KCNQ4, KCNQ5, and KCNQ4/5, respectively). Diclofenac (100 μM) inhibited KCNQ5 channels, reducing maximum conductance by 53%, but increased maximum conductance of KCNQ4 channels by 38%. The opposite effects of diclofenac on KCNQ4 and KCNQ5 could not be attributed to the presence of a basic residue (lysine) in the voltage-sensing domain of KCNQ5, because mutation of this residue to neutral glycine (the residue present in KCNQ4) resulted in a more effective block of the channel. Differences in deactivation rates and distinct voltage-dependent effects of diclofenac on channel activation and deactivation observed with each of the subunit combinations (KCNQ4, KCNQ5, and KCNQ4/5) were used as diagnostic tools to evaluate native KCNQ currents in vascular smooth muscle cells. A7r5 cells express only KCNQ5 channels endogenously, and their responses to diclofenac closely resembled those of the overexpressed KCNQ5 currents. In contrast, mesenteric artery myocytes, which express both KCNQ4 and KCNQ5 channels, displayed whole-cell KCNQ currents with properties and diclofenac responses characteristic of overexpressed heteromeric KCNQ4/5 channels. PMID:20876743

Inhibition of coronary blood flow by a vascular waterfall mechanism.

Science.gov (United States)

Downey, J M; Kirk, E S

1975-06-01

The mechanism whereby systole inhibits coronary blood flow was examined. A branch of the left coronary artery was maximally dilated with an adenosine infusion, and the pressure-flow relationship was obtained for beating and arrested states. The pressure-flow curve for the arrested state was shifted toward higher pressures and in the range of pressures above peak ventricular pressure was linear and parallel to that for the arrested state. Below this range the curve for the beating state converged toward that for the arrested state and was convex to the pressure axis. These results were compared with a model of the coronary vasculature that consisted of numerous parallel channels, each responding to local intramyocardial pressure by forming vascular waterfalls. When intramyocardial pressure in the model was assigned values from zero at the epicardium to peak ventricular pressure at the endocardium, pressure-flow curves similar to the experimental ones resulted. Thus, we conclude that systole inhibits coronary perfusion by the formation of vascular waterfalls and that the intramyocardial pressures responsible for this inhibition do not significantly exceed peak ventricular pressure.

Melatonin mediates vasodilation through both direct and indirect activation of BKCa channels.

Science.gov (United States)

Zhao, T; Zhang, H; Jin, C; Qiu, F; Wu, Y; Shi, L

2017-10-01

Melatonin, synthesized primarily by the pineal gland, is a neuroendocrine hormone with high membrane permeability. The vascular effects of melatonin, including vasoconstriction and vasodilation, have been demonstrated in numerous studies. However, the mechanisms underlying these effects are not fully understood. Large-conductance Ca 2+ -activated K + (BK Ca ) channels are expressed broadly on smooth muscle cells and play an important role in vascular tone regulation. This study explored the mechanisms of myocyte BK Ca channels and endothelial factors underlying the action of melatonin on the mesenteric arteries (MAs). Vascular contractility and patch-clamp studies were performed on myocytes of MAs from Wistar rats. Melatonin induced significant vasodilation on MAs. In the presence of N ω -nitro-l-arginine methyl ester (l-NAME), a potent endothelial oxide synthase (eNOS) inhibitor, melatonin elicited concentration-dependent relaxation, with lowered pIC 50 The effect of melatonin was significantly attenuated in the presence of BK Ca channel blocker iberiotoxin or MT1/MT2 receptor antagonist luzindole in both (+) l-NAME and (-) l-NAME groups. In the (+) l-NAME group, iberiotoxin caused a parallel rightward shift of the melatonin concentration-relaxation curve, with pIC 50 lower than that of luzindole. Both inside-out and cell-attached patch-clamp recordings showed that melatonin significantly increased the open probability, mean open time and voltage sensitivity of BK Ca channels. In a cell-attached patch-clamp configuration, the melatonin-induced enhancement of BK Ca channel activity was significantly suppressed by luzindole. These findings indicate that in addition to the activation of eNOS, melatonin-induced vasorelaxation of MAs is partially attributable to its direct (passing through the cell membrane) and indirect (via MT1/MT2 receptors) activation of the BK Ca channels on mesenteric arterial myocytes. © 2017 Society for Endocrinology.

Current concepts in the classification, diagnosis and treatment of vascular anomalies

International Nuclear Information System (INIS)

Ernemann, Ulrike; Kramer, Ulrich; Miller, Stephan; Bisdas, Sotirios; Rebmann, Hans; Breuninger, Helmut; Zwick, Christine; Hoffmann, Juergen

2010-01-01

Patients with extended vascular anomalies may suffer from significant aesthetic and functional impairment and represent a challenge to therapeutic planning, which is best met by an interdisciplinary concept. In agreement with the International Society for the Study of Vascular Anomalies (ISSVA), vascular lesions are classified into haemangiomas as proliferating endothelial tumours on the one hand and congenital vascular malformations on the other. According to the preponderant vascular channels and hemodynamic characteristics, malformations are subdivided into low flow (venous, lymphatic and capillary) lesions and high-flow malformations. Diagnostic imaging should be targeted at the specific structural and functional informations required for treatment planning. The imaging modality of choice to provide these informations is magnetic resonance imaging (MRI) supplemented by magnetic resonance angiography (MRA) with high spatial and temporal resolution. Treatment indications for haemangiomas depend on the proliferative behaviour of the lesion and comprise β-blockers in order to induce involution as well as cryotherapy, laser and open surgery. Interventional radiological procedures have evolved as an essential element in an interdisciplinary treatment plan for vascular malformations and include percutaneous sclerotherapy with ethanol and OK-432 for venous and lymphatic malformations and transarterial embolization for high-flow lesions.

Current concepts in the classification, diagnosis and treatment of vascular anomalies

Energy Technology Data Exchange (ETDEWEB)

Ernemann, Ulrike, E-mail: ulrike.ernemann@med.uni-tuebingen.d [Department of Diagnostic and Interventional Neuroradiology, Radiological Clinic, University Hospital Tuebingen, Hoppe-Seyler-Strasse 3, 72076 Tuebingen (Germany); Kramer, Ulrich; Miller, Stephan [Department of Diagnostic and Interventional Radiology, Radiological Clinic, University Hospital Tuebingen (Germany); Bisdas, Sotirios [Department of Diagnostic and Interventional Neuroradiology, Radiological Clinic, University Hospital Tuebingen, Hoppe-Seyler-Strasse 3, 72076 Tuebingen (Germany); Rebmann, Hans [Department of Paediatrics, Children' s Hospital, University Hospital Tuebingen (Germany); Breuninger, Helmut [Department of Dermatology, University Hospital Tuebingen (Germany); Zwick, Christine [Department of Hand, Plastic, Reconstructive and Burns Surgery, BG Trauma Clinic Tuebingen, University Hospital Tuebingen (Germany); Hoffmann, Juergen [Department of Oral and Maxillofacial Surgery, University Hospital Tuebingen (Germany)

2010-07-15

Patients with extended vascular anomalies may suffer from significant aesthetic and functional impairment and represent a challenge to therapeutic planning, which is best met by an interdisciplinary concept. In agreement with the International Society for the Study of Vascular Anomalies (ISSVA), vascular lesions are classified into haemangiomas as proliferating endothelial tumours on the one hand and congenital vascular malformations on the other. According to the preponderant vascular channels and hemodynamic characteristics, malformations are subdivided into low flow (venous, lymphatic and capillary) lesions and high-flow malformations. Diagnostic imaging should be targeted at the specific structural and functional informations required for treatment planning. The imaging modality of choice to provide these informations is magnetic resonance imaging (MRI) supplemented by magnetic resonance angiography (MRA) with high spatial and temporal resolution. Treatment indications for haemangiomas depend on the proliferative behaviour of the lesion and comprise {beta}-blockers in order to induce involution as well as cryotherapy, laser and open surgery. Interventional radiological procedures have evolved as an essential element in an interdisciplinary treatment plan for vascular malformations and include percutaneous sclerotherapy with ethanol and OK-432 for venous and lymphatic malformations and transarterial embolization for high-flow lesions.

Results From a Channel Restoration Project: Hydraulic Design Considerations

Science.gov (United States)

Karle, K.F.; Densmore, R.V.; ,

2001-01-01

Techniques for the hydraulic restoration of placer-mined streams and floodplains were developed in Denali National Park and Preserve, Alaska. The two-year study at Glen Creek focused on a design of stream and floodplain geometry using hydraulic capacity and shear stress equations. Slope and sinuosity values were based on regional relationships. Design requirements included a channel capacity for a bankfull discharge and a floodplain capacity for a 1.5- to 100-year discharge. Several bio-engineering techniques using alder and willow, including anchored brush bars, streambank hedge layering, seedlings, and cuttings, were tested to dissipate floodwater energy and encourage sediment deposition until natural revegetation stabilized the new floodplains. Permanently monumented cross-sections installed throughout the project site were surveyed every one to three years. Nine years after the project began, a summer flood caused substantial damage to the channel form, including a change in width/depth ratio, slope, and thalweg location. Many of the alder brush bars were heavily damaged or destroyed, resulting in significant bank erosion. This paper reviews the original hydraulic design process, and describes changes to the channel and floodplain geometry over time, based on nine years of cross-section surveys.

Kaempferol enhances endothelium-dependent relaxation in the porcine coronary artery through activation of large-conductance a2+-activated K+ channels

Science.gov (United States)

Xu, Y C; Leung, S W S; Leung, G P H; Man, R Y K

2015-01-01

Background and Purpose Kaempferol, a plant flavonoid present in normal human diet, can modulate vasomotor tone. The present study aimed to elucidate the signalling pathway through which this flavonoid enhanced relaxation of vascular smooth muscle. Experimental Approach The effect of kaempferol on the relaxation of porcine coronary arteries to endothelium-dependent (bradykinin) and -independent (sodium nitroprusside) relaxing agents was studied in an in vitro organ chamber setup. The whole-cell patch-clamp technique was used to determine the effect of kaempferol on potassium channels in porcine coronary artery smooth muscle cells (PCASMCs). Key Results At a concentration without direct effect on vascular tone, kaempferol (3 × 10−6 M) enhanced relaxations produced by bradykinin and sodium nitroprusside. The potentiation by kaempferol of the bradykinin-induced relaxation was not affected by Nω-nitro-L-arginine methyl ester, an inhibitor of NO synthase (10−4 M) or TRAM-34 plus UCL 1684, inhibitors of intermediate- and small-conductance calcium-activated potassium channels, respectively (10−6 M each), but was abolished by tetraethylammonium chloride, a non-selective inhibitor of calcium-activated potassium channels (10−3 M), and iberiotoxin, a selective inhibitor of large-conductance calcium-activated potassium channel (KCa1.1; 10−7 M). Iberiotoxin also inhibited the potentiation by kaempferol of sodium nitroprusside-induced relaxations. Kaempferol stimulated an outward-rectifying current in PCASMCs, which was abolished by iberiotoxin. Conclusions and Implications The present results suggest that, in smooth muscle cells of the porcine coronary artery, kaempferol enhanced relaxations caused by endothelium-derived and exogenous NO as well as those due to endothelium-dependent hyperpolarization. This vascular effect of kaempferol involved the activation of KCa1.1 channels. PMID:25652142

Clinical results of stereotactic heavy-charged-particle radiosurgery for intracranial angiographically occult vascular malformations

International Nuclear Information System (INIS)

Levy, R.P.; Fabrikant, J.I.; Phillips, M.H.; Frankel, K.A.; Steinberg, G.K.; Marks, M.P.; DeLaPaz, R.L.; Chuang, F.Y.S.; Lyman, J.T.

1989-12-01

Angiographically occult vascular malformations (AOVMs) of the brain have been recognized for many years to cause neurologic morbidity and mortality. They generally become symptomatic due to intracranial hemorrhage, focal mass effect, seizures or headaches. The true incidence of AOVMs is unknown, but autopsy studies suggest that they are more common than high-flow angiographically demonstrable arteriovenous malformations (AVMs). We have developed stereotactic heavy-charged-particle Bragg peak radiosurgery for the treatment of inoperable intracranial vascular malformations, using the helium ion beams at the Lawrence Berkeley Laboratory 184-inch Synchrocyclotron and Bevatron. This report describes the protocol for patient selection, radiosurgical treatment planning method, clinical and neuroradiologic results and complications encountered, and discusses the strengths and limitations of the method. 10 refs., 1 fig

Clinical results of stereotactic heavy-charged-particle radiosurgery for intracranial angiographically occult vascular malformations

Energy Technology Data Exchange (ETDEWEB)

Levy, R.P.; Fabrikant, J.I.; Phillips, M.H.; Frankel, K.A.; Steinberg, G.K.; Marks, M.P.; DeLaPaz, R.L.; Chuang, F.Y.S.; Lyman, J.T.

1989-12-01

Angiographically occult vascular malformations (AOVMs) of the brain have been recognized for many years to cause neurologic morbidity and mortality. They generally become symptomatic due to intracranial hemorrhage, focal mass effect, seizures or headaches. The true incidence of AOVMs is unknown, but autopsy studies suggest that they are more common than high-flow angiographically demonstrable arteriovenous malformations (AVMs). We have developed stereotactic heavy-charged-particle Bragg peak radiosurgery for the treatment of inoperable intracranial vascular malformations, using the helium ion beams at the Lawrence Berkeley Laboratory 184-inch Synchrocyclotron and Bevatron. This report describes the protocol for patient selection, radiosurgical treatment planning method, clinical and neuroradiologic results and complications encountered, and discusses the strengths and limitations of the method. 10 refs., 1 fig.

An Analysis of Responses to Defibrotide in the Pulmonary Vascular Bed of the Cat.

Science.gov (United States)

Kaye, Alan D; Skonieczny, Brendan D; Kaye, Aaron J; Harris, Zoey I; Luk, Eric J

2016-01-01

Defibrotide is a polydisperse mixture of single-stranded oligonucleotides with many pharmacologic properties and multiple actions on the vascular endothelium. Responses to defibrotide and other vasodepressor agents were evaluated in the pulmonary vascular bed of the cat under conditions of controlled pulmonary blood flow and constant left atrial pressure. Lobar arterial pressure was increased to a high steady level with the thromboxane A2 analog U-46619. Under increased-tone conditions, defibrotide caused dose-dependent decreases in lobar arterial pressure without altering systemic arterial and left atrial pressures. Responses to defibrotide were significantly attenuated after the administration of the cyclooxygenase inhibitor sodium meclofenamate. Responses to defibrotide were also significantly attenuated after the administration of both the adenosine 1 and 2 receptor antagonists 8-cyclopentyl-1,3-dimethylxanthine and 8-(3-chlorostyryl)caffeine. Responses to defibrotide were not altered after the administration of the vascular selective adenosine triphosphate-sensitive potassium channel blocker U-37883A, or after the administration of the nitric oxide synthase inhibitor L-N-(1-iminoethyl)-ornithine. These data show that defibrotide has significant vasodepressor activity in the pulmonary vascular bed of the cat. They also suggest that pulmonary vasodilator responses to defibrotide are partially dependent on both the activation of the cyclooxygenase enzyme and adenosine 1 and 2 receptor pathways and independent of the activation of adenosine triphosphate-sensitive potassium channels or the synthesis of nitric oxide in the pulmonary vascular bed of the cat.

Angiographic findings of collateral vessels in cervicofacial vascular lesions with previously ligated carotid artery

International Nuclear Information System (INIS)

Na, Dong Gyu; Han, Moon Hee; Chang, Kee Hyun; Han, Gi Seok; Yeon, Kung Mo

1995-01-01

The purpose of this study is to describe the angiographic findings of collateral vessels in cervicofacial vascular lesions with previously ligated carotid arteries and to evaluate the extent of angiographic assessment needed before embolization. We retrospectively reviewed 10 cervicofacial vascular lesions with previously ligated carotid artery, which were 6 cases of arteriovenous malformation, 2 cases of carotid cavernous fistula, 1 case of hemangioma and 1 case of arteriovenous malformation with carotid cavernous fistula. The previously ligated arteries are proximal external carotid artery (n = 5), branches of external carotid artery (n = 2) and common carotid artery (n = 3). Common carotid artery or internal carotid artery (n = 9), vertebral artery (n = 5), ipsilateral external carotid artery (n = 4), contralateral external carotid artery (n = 5), costocervical trunk (n = 2), thyrocervical trunk (n = 2) were assessed by conventional angiography. Angiography of both carotid and vertebral arteries was performed in 5 cases. The collateral vascular channels were inferolateral trunk of internal carotid artery (n = 8), vertebral artery (n = 5), contralateral external carotid artery (n = 5), ipsilateral external carotid artery (n = 4), deep cervical artery (n = 2) and ascending cervical artery (n = 1). Embolization were performed in 9 cases with operative cannulation (n = 4), embolization via collateral branches of ipsilateral external carotid artery (n = 1), embolization via collateral branches of contralateral external carotid artery (n = 3) and balloon occlusion via direct puncture (n = 1). The collateral channels in cervicofacial vascular lesions with previously ligated carotid artery were inferolateral trunk of internal carotid artery, contralateral or ipsilateral external carotid artery, vertebral artery, deep cervical artery and ascending cervical artery on angiography. Complete angiographic assessment of possible collateral channels is mandatory for the

High affinity complexes of pannexin channels and L-type calcium channel splice-variants in human lung: Possible role in clevidipine-induced dyspnea relief in acute heart failure

Directory of Open Access Journals (Sweden)

Gerhard P. Dahl

2016-08-01

Research in Context: Clevidipine lowers blood pressure by inhibiting calcium channels in vascular smooth muscle. In patients with acute heart failure, clevidipine was shown to relieve breathing problems. This was only partially related to the blood pressure lowering actions of clevidipine and not conferred by another calcium channel inhibitor. We here found calcium channel variants in human lung that are more selectively inhibited by clevidipine, especially when associated with pannexin channels. This study gives a possible mechanism for clevidipine's relief of breathing problems and supports future clinical trials testing the role of clevidipine in the treatment of acute heart failure.

FPGA based, DSP integrated, 8-channel SIMCON, ver. 3.0. Initial results for 8-channel algorithm

Energy Technology Data Exchange (ETDEWEB)

Giergusiewicz, W.; Koprek, W.; Jalmuzna, W.; Pozniak, K.T.; Romaniuk, R.S. [Warsaw Univ. of Technology (Poland). Inst. of Electronic Systems

2005-07-01

The paper describes design, construction and initial measurements of an eight channel electronic LLRF device predicted for building of the control system for the VUV-FEL accelerator at DESY (Hamburg). The device, referred in the paper to as the SIMCON 3.0 (from the SC cavity simulator and controller) consists of a 16 layer, VME size, PCB, a large FPGA chip (VirtexII-4000 by Xilinx), eight fast ADCs and four DACs (by Analog Devices). To our knowledge, the proposed device is the first of this kind for the accelerator technology in which there was achieved (the FPGA based) DSP latency below 200 ns. With the optimized data transmission system, the overall LLRF system latency can be as low as 500 ns. The SIMCON 3.0 sub-system was applied for initial tests with the ACC1 module of the VUV FEL accelerator (eight channels) and with the CHECHIA test stand (single channel), both at the DESY. The promising results with the SIMCON 3.0. encouraged us to enter the design of SIMCON 3.1. possessing 10 measurement and control channels and some additional features to be reported in the next technical note. SIMCON 3.0. is a modular solution, while SIMCON 3.1. will be an integrated board of the all-in-one type. Two design approaches - modular and all-in-one, after branching off in this version of the Simcon, will be continued. (orig.)

Experimental studies in a single-phase parallel channel natural circulation system. Preliminary results

International Nuclear Information System (INIS)

Bodkha, Kapil; Pilkhwal, D.S.; Jana, S.S.; Vijayan, P.K.

2016-01-01

Natural circulation systems find extensive applications in industrial engineering systems. One of the applications is in nuclear reactor where the decay heat is removed by natural circulation of the fluid under off-normal conditions. The upcoming reactor designs make use of natural circulation in order to remove the heat from core under normal operating conditions also. These reactors employ multiple vertical fuel channels with provision of on-power refueling/defueling. Natural circulation systems are relatively simple, safe and reliable when compared to forced circulation systems. However, natural circulation systems are prone to encounter flow instabilities which are highly undesirable for various reasons. Presence of parallel channels under natural circulation makes the system more complicated. To examine the behavior of parallel channel system, studies were carried out for single-phase natural circulation flow in a multiple vertical channel system. The objective of the present work is to study the flow behavior of the parallel heated channel system under natural circulation for different operating conditions. Steady state and transient studies have been carried out in a parallel channel natural circulation system with three heated channels. The paper brings out the details of the system considered, different cases analyzed and preliminary results of studies carried out on a single-phase parallel channel system.

The KATP channel in migraine pathophysiology: a novel therapeutic target for migraine.

Science.gov (United States)

Al-Karagholi, Mohammad Al-Mahdi; Hansen, Jakob Møller; Severinsen, Johanne; Jansen-Olesen, Inger; Ashina, Messoud

2017-08-23

To review the distribution and function of K ATP channels, describe the use of K ATP channels openers in clinical trials and make the case that these channels may play a role in headache and migraine. K ATP channels are widely present in the trigeminovascular system and play an important role in the regulation of tone in cerebral and meningeal arteries. Clinical trials using synthetic K ATP channel openers report headache as a prevalent-side effect in non-migraine sufferers, indicating that K ATP channel opening may cause headache, possibly due to vascular mechanisms. Whether K ATP channel openers can provoke migraine in migraine sufferers is not known. We suggest that K ATP channels may play an important role in migraine pathogenesis and could be a potential novel therapeutic anti-migraine target.

Kaempferol enhances endothelium-dependent relaxation in the porcine coronary artery through activation of large-conductance Ca(2+) -activated K(+) channels.

Science.gov (United States)

Xu, Y C; Leung, S W S; Leung, G P H; Man, R Y K

2015-06-01

Kaempferol, a plant flavonoid present in normal human diet, can modulate vasomotor tone. The present study aimed to elucidate the signalling pathway through which this flavonoid enhanced relaxation of vascular smooth muscle. The effect of kaempferol on the relaxation of porcine coronary arteries to endothelium-dependent (bradykinin) and -independent (sodium nitroprusside) relaxing agents was studied in an in vitro organ chamber setup. The whole-cell patch-clamp technique was used to determine the effect of kaempferol on potassium channels in porcine coronary artery smooth muscle cells (PCASMCs). At a concentration without direct effect on vascular tone, kaempferol (3 × 10(-6) M) enhanced relaxations produced by bradykinin and sodium nitroprusside. The potentiation by kaempferol of the bradykinin-induced relaxation was not affected by N(ω)-nitro-L-arginine methyl ester, an inhibitor of NO synthase (10(-4) M) or TRAM-34 plus UCL 1684, inhibitors of intermediate- and small-conductance calcium-activated potassium channels, respectively (10(-6) M each), but was abolished by tetraethylammonium chloride, a non-selective inhibitor of calcium-activated potassium channels (10(-3) M), and iberiotoxin, a selective inhibitor of large-conductance calcium-activated potassium channel (KCa 1.1; 10(-7) M). Iberiotoxin also inhibited the potentiation by kaempferol of sodium nitroprusside-induced relaxations. Kaempferol stimulated an outward-rectifying current in PCASMCs, which was abolished by iberiotoxin. The present results suggest that, in smooth muscle cells of the porcine coronary artery, kaempferol enhanced relaxations caused by endothelium-derived and exogenous NO as well as those due to endothelium-dependent hyperpolarization. This vascular effect of kaempferol involved the activation of KCa 1.1 channels. © 2015 The British Pharmacological Society.

Experimental test results of multi-channel test rig of T1 test section, 5

International Nuclear Information System (INIS)

Hino, Ryutaro; Takase, Kazuyuki; Miyamoto, Yoshiaki

1990-09-01

Channel blockage test on a fuel column of the high temperature engineering test reactor (HTTR) has been performed under the helium gas atmosphere at a high temperature and a high pressure in order to obtain safety data on flow rate and temperature distributions in the fuel column with the multi-channel test rig of the fuel stack test section (T 1 ) in HENDEL. In the test, one of 12 fuel channels was blockaded to 90% of flow area at the channel inlet. Experimental results showed that the helium gas flow rate in the blockaded channel was 28%∼33% lower than the average flow rate for Reynolds number from 2300 to 14000 in isothermal flow. When simulated fuel rods were heated, the flow rate in the blockaded channel did not decrease down in comparison with the isothermal flow. This is due to that the heat generated in the fuel rods conducts to the other fuel channels in graphite fuel blocks, so that accelerated pressure losses in the fuel channels change with helium gas temperatures. (author)

Bioprinting for vascular and vascularized tissue biofabrication.

Science.gov (United States)

Datta, Pallab; Ayan, Bugra; Ozbolat, Ibrahim T

2017-03-15

Bioprinting is a promising technology to fabricate design-specific tissue constructs due to its ability to create complex, heterocellular structures with anatomical precision. Bioprinting enables the deposition of various biologics including growth factors, cells, genes, neo-tissues and extra-cellular matrix-like hydrogels. Benefits of bioprinting have started to make a mark in the fields of tissue engineering, regenerative medicine and pharmaceutics. Specifically, in the field of tissue engineering, the creation of vascularized tissue constructs has remained a principal challenge till date. However, given the myriad advantages over other biofabrication methods, it becomes organic to expect that bioprinting can provide a viable solution for the vascularization problem, and facilitate the clinical translation of tissue engineered constructs. This article provides a comprehensive account of bioprinting of vascular and vascularized tissue constructs. The review is structured as introducing the scope of bioprinting in tissue engineering applications, key vascular anatomical features and then a thorough coverage of 3D bioprinting using extrusion-, droplet- and laser-based bioprinting for fabrication of vascular tissue constructs. The review then provides the reader with the use of bioprinting for obtaining thick vascularized tissues using sacrificial bioink materials. Current challenges are discussed, a comparative evaluation of different bioprinting modalities is presented and future prospects are provided to the reader. Biofabrication of living tissues and organs at the clinically-relevant volumes vitally depends on the integration of vascular network. Despite the great progress in traditional biofabrication approaches, building perfusable hierarchical vascular network is a major challenge. Bioprinting is an emerging technology to fabricate design-specific tissue constructs due to its ability to create complex, heterocellular structures with anatomical precision

The diaphragms of fenestrated endothelia: gatekeepers of vascular permeability and blood composition.

Science.gov (United States)

Stan, Radu V; Tse, Dan; Deharvengt, Sophie J; Smits, Nicole C; Xu, Yan; Luciano, Marcus R; McGarry, Caitlin L; Buitendijk, Maarten; Nemani, Krishnamurthy V; Elgueta, Raul; Kobayashi, Takashi; Shipman, Samantha L; Moodie, Karen L; Daghlian, Charles P; Ernst, Patricia A; Lee, Hong-Kee; Suriawinata, Arief A; Schned, Alan R; Longnecker, Daniel S; Fiering, Steven N; Noelle, Randolph J; Gimi, Barjor; Shworak, Nicholas W; Carrière, Catherine

2012-12-11

Fenestral and stomatal diaphragms are endothelial subcellular structures of unknown function that form on organelles implicated in vascular permeability: fenestrae, transendothelial channels, and caveolae. PV1 protein is required for diaphragm formation in vitro. Here, we report that deletion of the PV1-encoding Plvap gene in mice results in the absence of diaphragms and decreased survival. Loss of diaphragms did not affect the fenestrae and transendothelial channels formation but disrupted the barrier function of fenestrated capillaries, causing a major leak of plasma proteins. This disruption results in early death of animals due to severe noninflammatory protein-losing enteropathy. Deletion of PV1 in endothelium, but not in the hematopoietic compartment, recapitulates the phenotype of global PV1 deletion, whereas endothelial reconstitution of PV1 rescues the phenotype. Taken together, these data provide genetic evidence for the critical role of the diaphragms in fenestrated capillaries in the maintenance of blood composition. Copyright © 2012 Elsevier Inc. All rights reserved.

Functional Importance of L- and P/Q-Type Voltage-Gated Calcium Channels in Human Renal Vasculature

DEFF Research Database (Denmark)

Hansen, Pernille B; Poulsen, Christian B; Walter, Steen

2011-01-01

Calcium channel blockers are widely used for treatment of hypertension, because they decrease peripheral vascular resistance through inhibition of voltage-gated calcium channels. Animal studies of renal vasculature have shown expression of several types of calcium channels that are involved......-type subtype (Ca(v) 3.1 and Ca(v) 3.2) voltage-gated calcium channels (Ca(v)s), and quantitative PCR showed highest expression of L-type channels in renal arteries and variable expression between patients of subtypes of calcium channels in intrarenal vessels. Immunohistochemical labeling of kidney sections...

Development of a Two-Channel Simultaneous Photoplethysmography Recording System

Directory of Open Access Journals (Sweden)

Kim Soon Chong

2013-09-01

Full Text Available Multi-site photoplethysmograph  (PPG recording enables researchers to study the vascular and hemodynamic  properties of human subjects. Currently, there  is  no  commercial  system  available  in  the  market  to  perform  either  one channel or multi-channel PPG recording. PPG is an optoelectronic technique that measures  changes  in  blood  volume  associated  with  cardiac  contraction.  The measurements  can  be  obtained  from  fingertips,  ear  lobes  and toes  due  to  their low absorption and high degree of vasculature. The main objective of this project is to develop a two-channel simultaneous PPG recording system to acquire PPG signals  from  two  different  physiological  sites  using  a  Nellcor  equivalent  PPG probe.  MATLAB  software  was  used  during  the  development  phase  to  ensure rapid prototyping. The experiment results show that there was no inter -channel delay in the developed two-channel PPG system. Our preliminary results show that the delays between the left and the right arm were from 4 to 12 ms in three healthy random subjects. The system is portable, powered by universal serial bus (USB and allows the user to do the PPG data acquisition in a clinical setting.

A Microfluidic Approach for Studying Piezo Channels.

Science.gov (United States)

Maneshi, M M; Gottlieb, P A; Hua, S Z

2017-01-01

Microfluidics is an interdisciplinary field intersecting many areas in engineering. Utilizing a combination of physics, chemistry, biology, and biotechnology, along with practical applications for designing devices that use low volumes of fluids to achieve high-throughput screening, is a major goal in microfluidics. Microfluidic approaches allow the study of cells growth and differentiation using a variety of conditions including control of fluid flow that generates shear stress. Recently, Piezo1 channels were shown to respond to fluid shear stress and are crucial for vascular development. This channel is ideal for studying fluid shear stress applied to cells using microfluidic devices. We have developed an approach that allows us to analyze the role of Piezo channels on any given cell and serves as a high-throughput screen for drug discovery. We show that this approach can provide detailed information about the inhibitors of Piezo channels. Copyright © 2017 Elsevier Inc. All rights reserved.

Brain Perivascular Spaces as Biomarkers of Vascular Risk: Results from the Northern Manhattan Study.

Science.gov (United States)

Gutierrez, J; Elkind, M S V; Dong, C; Di Tullio, M; Rundek, T; Sacco, R L; Wright, C B

2017-05-01

Dilated perivascular spaces in the brain are associated with greater arterial pulsatility. We hypothesized that perivascular spaces identify individuals at higher risk for systemic and cerebral vascular events. Stroke-free participants in the population-based Northern Manhattan Study had brain MR imaging performed and were followed for myocardial infarction, any stroke, and death. Imaging analyses distinguished perivascular spaces from lesions presumably ischemic. Perivascular spaces were further subdivided into lesions with diameters of ≤3 mm (small perivascular spaces) and >3 mm (large perivascular spaces). We calculated relative rates of events with Poisson models and hazard ratios with Cox proportional models. The Northern Manhattan Study participants who had MR imaging data available for review ( n = 1228; 59% women, 65% Hispanic; mean age, 71 ± 9 years) were followed for an average of 9 ± 2 years. Participants in the highest tertile of the small perivascular space score had a higher relative rate of all deaths (relative rate, 1.38; 95% CI, 1.01-1.91), vascular death (relative rate, 1.87; 95% CI, 1.12-3.14), myocardial infarction (relative rate, 2.08; 95% CI, 1.01-4.31), any stroke (relative rate, 1.79; 95% CI, 1.03-3.11), and any vascular event (relative rate, 1.74; 95% CI, 1.18-2.56). After we adjusted for confounders, there was a higher risk of vascular death (hazard ratio, 1.06; 95% CI, 1.01-1.11), myocardial infarction (hazard ratio, 2.22; 95% CI, 1.12-4.42), and any vascular event (hazard ratio, 1.04; 95% CI, 1.01-1.08) with higher small perivascular space scores. In this multiethnic, population-based study, participants with a high burden of small perivascular spaces had increased risk of vascular events. By gaining pathophysiologic insight into the mechanism of perivascular space dilation, we may be able to propose novel therapies to better prevent vascular disorders in the population. © 2017 by American Journal of Neuroradiology.

Reduction in renal blood flow following administration of norepinephrine and phenylephrine in septic rats treated with Kir6.1 ATP-sensitive and KCa1.1 calcium-activated K+ channel blockers.

Science.gov (United States)

da Rosa Maggi Sant'Helena, Bruna; Guarido, Karla L; de Souza, Priscila; Crestani, Sandra; da Silva-Santos, J Eduardo

2015-10-15

We evaluated the effects of K+ channel blockers in the vascular reactivity of in vitro perfused kidneys, as well as on the influence of vasoactive agents in the renal blood flow of rats subjected to the cecal ligation and puncture (CLP) model of sepsis. Both norepinephrine and phenylephrine had the ability to increase the vascular perfusion pressure reduced in kidneys of rats subjected to CLP at 18 h and 36 h before the experiments. The non-selective K+ channel blocker tetraethylammonium, but not the Kir6.1 blocker glibenclamide, normalized the effects of phenylephrine in kidneys from the CLP 18 h group. Systemic administration of tetraethylammonium, glibenclamide, or the KCa1.1 blocker iberiotoxin, did not change the renal blood flow in control or septic rats. Norepinephrine or phenylephrine also had no influence on the renal blood flow of septic animals, but its injection in rats from the CLP 18 h group previously treated with either glibenclamide or iberiotoxin resulted in an exacerbated reduction in the renal blood flow. These results suggest an abnormal functionality of K+ channels in the renal vascular bed in sepsis, and that the blockage of different subtypes of K+ channels may be deleterious for blood perfusion in kidneys, mainly when associated with vasoactive drugs. Copyright © 2015 Elsevier B.V. All rights reserved.

Channel Power in Multi-Channel Environments

NARCIS (Netherlands)

M.G. Dekimpe (Marnik); B. Skiera (Bernd)

2004-01-01

textabstractIn the literature, little attention has been paid to instances where companies add an Internet channel to their direct channel portfolio. However, actively managing multiple sales channels requires knowing the customers’ channel preferences and the resulting channel power. Two key

Preparation and features of polycaprolactone vascular grafts with the incorporated vascular endothelial growth factor

Energy Technology Data Exchange (ETDEWEB)

Sevostyanova, V. V., E-mail: sevostyanova.victoria@gmail.com; Khodyrevskaya, Y. I.; Glushkova, T. V.; Antonova, L. V.; Kudryavtseva, Y. A.; Barbarash, O. L.; Barbarash, L. S. [Research Institute for Complex Issues of Cardiovascular Diseases, Kemerovo (Russian Federation)

2015-10-27

The development of tissue-engineered small-diameter vascular grafts is an urgent issue in cardiovascular surgery. In this study, we assessed how the incorporation of the vascular endothelial growth factor (VEGF) affects morphological and mechanical properties of polycaprolactone (PCL) vascular grafts along with its release kinetics. Vascular grafts were prepared using two-phase electrospinning. In pursuing our aims, we performed scanning electron microscopy, mechanical testing, and enzyme-linked immunosorbent assay. Our results demonstrated the preservation of a highly porous structure and improvement of PCL/VEGF scaffold mechanical properties as compared to PCL grafts. A prolonged VEGF release testifies the use of this construct as a scaffold for tissue-engineered vascular grafts.

Ruthenium Complexes as NO Donors for Vascular Relaxation Induction

Directory of Open Access Journals (Sweden)

Renata Galvão de Lima

2014-07-01

Full Text Available Nitric oxide (NO donors are substances that can release NO. Vascular relaxation induction is among the several functions of NO, and the administration of NO donors is a pharmacological alternative to treat hypertension. This review will focus on the physicochemical description of ruthenium-derived NO donor complexes that release NO via reduction and light stimulation. In particular, we will discuss the complexes synthesized by our research group over the last ten years, and we will focus on the vasodilation and arterial pressure control elicited by these complexes. Soluble guanylyl cyclase (sGC and potassium channels are the main targets of the NO species released from the inorganic compounds. We will consider the importance of the chemical structure of the ruthenium complexes and their vascular effects.

Molecular studies of BKCa channels in intracranial arteries

DEFF Research Database (Denmark)

Wulf, Helle; Hay-Schmidt, Anders; Poulsen, Asser Nyander

2008-01-01

expression of the BK(Ca) channel in rat basilar, middle cerebral, and middle meningeal arteries by reverse transcription polymerase chain reaction (RT-PCR), quantitative real-time PCR, and Western blotting. Distribution patterns were investigated using in situ hybridization and immunofluorescence studies. RT......  Large conductance calcium-activated potassium channels (BK(ca)) are crucial for the regulation of cerebral vascular basal tone and might be involved in cerebral vasodilation relevant to migraine and stroke. We studied the differential gene expression of mRNA transcript levels and protein......-PCR and quantitative real-time PCR detected the expression of the BK(Ca) channel mRNA transcript in rat basilar, middle cerebral, and middle meningeal arteries, with the transcript being expressed more abundantly in rat basilar arteries than in middle cerebral and middle meningeal arteries. Western blotting detected...

Differential expression of BK channel isoforms and beta-subunits in rat neuro-vascular tissues

DEFF Research Database (Denmark)

Poulsen, Asser Nyander; Wulf, Helle; Hay-Schmidt, Anders

2009-01-01

We investigated the expression of splice variants and beta-subunits of the BK channel (big conductance Ca(2+)-activated K(+) channel, Slo1, MaxiK, K(Ca)1.1) in rat cerebral blood vessels, meninges, trigeminal ganglion among other tissues. An alpha-subunit splice variant X1(+24) was found expresse...

Characterization of printable cellular micro-fluidic channels for tissue engineering

International Nuclear Information System (INIS)

Zhang, Yahui; Chen, Howard; Ozbolat, Ibrahim T; Yu, Yin

2013-01-01

Tissue engineering has been a promising field of research, offering hope of bridging the gap between organ shortage and transplantation needs. However, building three-dimensional (3D) vascularized organs remains the main technological barrier to be overcome. One of the major challenges is the inclusion of a vascular network to support cell viability in terms of nutrients and oxygen perfusion. This paper introduces a new approach to the fabrication of vessel-like microfluidic channels that has the potential to be used in thick tissue or organ fabrication in the future. In this research, we investigate the manufacturability of printable micro-fluidic channels, where micro-fluidic channels support mechanical integrity as well as enable fluid transport in 3D. A pressure-assisted solid freeform fabrication platform is developed with a coaxial needle dispenser unit to print hollow hydrogel filaments. The dispensing rheology is studied, and effects of material properties on structural formation of hollow filaments are analyzed. Sample structures are printed through the developed computer-controlled system. In addition, cell viability and gene expression studies are presented in this paper. Cell viability shows that cartilage progenitor cells (CPCs) maintained their viability right after bioprinting and during prolonged in vitro culture. Real-time PCR analysis yielded a relatively higher expression of cartilage-specific genes in alginate hollow filament encapsulating CPCs, compared with monolayer cultured CPCs, which revealed that printable semi-permeable micro-fluidic channels provided an ideal environment for cell growth and function. (paper)

Hyperhomocysteinemia potentiates diabetes-impaired EDHF-induced vascular relaxation: Role of insufficient hydrogen sulfide

Directory of Open Access Journals (Sweden)

Zhongjian Cheng

2018-06-01

Full Text Available Insufficient hydrogen sulfide (H2S has been implicated in Type 2 diabetic mellitus (T2DM and hyperhomocysteinemia (HHcy-related cardiovascular complications. We investigated the role of H2S in T2DM and HHcy-induced endothelial dysfunction in small mesenteric artery (SMA of db/db mice fed a high methionine (HM diet. HM diet (8 weeks induced HHcy in both T2DM db/db mice and non-diabetic db/+ mice (total plasma Hcy: 48.4 and 31.3 µM, respectively, and aggravated the impaired endothelium-derived hyperpolarization factor (EDHF-induced endothelium-dependent relaxation to acetylcholine (ACh, determined by the presence of eNOS inhibitor N(ω-nitro-L-arginine methyl ester (L-NAME and prostacyclin (PGI2 inhibitor indomethacin (INDO, in SMA from db/db mice but not that from db/+ mice. A non-selective Ca2+-active potassium channel (KCa opener NS309 rescued T2DM/HHcy-impaired EDHF-mediated vascular relaxation to ACh. EDHF-induced relaxation to ACh was inhibited by a non-selective KCa blocker TEA and intermediate-conductance KCa blocker (IKCa Tram-34, but not by small-conductance KCa (SKCa blocker Apamin. HHcy potentiated the reduction of free sulfide, H2S and cystathionine γ-lyase protein, which converts L-cysteine to H2S, in SMA of db/db mice. Importantly, a stable H2S donor DATS diminished the enhanced O2- production in SMAs and lung endothelial cells of T2DM/HHcy mice. Antioxidant PEG-SOD and DATS improved T2DM/HHcy impaired relaxation to ACh. Moreover, HHcy increased hyperglycemia-induced IKCa tyrosine nitration in human micro-vascular endothelial cells. EDHF-induced vascular relaxation to L-cysteine was not altered, whereas such relaxation to NaHS was potentiated by HHcy in SMA of db/db mice which was abolished by ATP-sensitive potassium channel blocker Glycolamide but not by KCa blockers. Conclusions: Intermediate HHcy potentiated H2S reduction via CSE-downregulation in microvasculature of T2DM mice. H2S is justified as an EDHF. Insufficient H2S

Injuries as a result of sports and vacation activities: Fractures with concomitant vascular injuries. Diagnosis and treatment concept

International Nuclear Information System (INIS)

Schlickewei, W.; Kuner, E.H.; Goetze, B.; Spillner, G.

1989-01-01

Extremity fractures with concomitant vascular injuries are surgical emergencies. Especially injuries of the upper extremities require a preoperative angiographic examination for the localization of the vascular lesion. In vascular lesions of the lower extremities a primary angiography is not necessary, if there is an opportunity for an intraoperative radiologic evaluation. In our traumatological department 104 patients were treated over the last 15 years with that combined injury. The concept of immediate stabilization of the fracture with simultaneous or postponed arterial repair has been proved to be appropriate. The fasziotomy as prophylactic procedure of a postischemic compartment syndrome is also a part of our concept during the last years. The late results in our mostly young patients depended on the degree of soft tissue damage and the time of ischemia. The often untreatable nerve lesions contributed to a loss of use of about 30% in the late courses. (orig.) [de

Major Vascular Neurocognitive Disorder: A Reappraisal to Vascular Dementia

Directory of Open Access Journals (Sweden)

Emre Kumral

2017-03-01

Full Text Available Major vascular neurocognitive disorder (NCD is the second leading form of dementia after Alzheimer’s disease, accounting for 17-20% of all dementias. Vascular NCD is a progressive disease caused by reduced cerebral blood flow related to multiple large volume or lacunar infarcts that induce a sudden onset and stepwise decline in cognitive abilities. Despite its prevalence and clinical importance, there is still controversy in the terminology of vascular NCD. Only after the release of Diagnostic and Statistical Manual of Mental Disorders-5 (DSM-5 (2013 did the American Psychiatric Association define vascular dementia as “major vascular NCD”. This review includes an overview of risk factors, pathophysiology, types, diagnostic and clinical features of major vascular NCD, and current treatment options of vascular NCD regarding to DSM-5 criteria

PDGF-induced migration of synthetic vascular smooth muscle cells through c-Src-activated L-type Ca2+ channels with full-length CaV1.2 C-terminus.

Science.gov (United States)

Guo, Xiaoguang; Kashihara, Toshihide; Nakada, Tsutomu; Aoyama, Toshifumi; Yamada, Mitsuhiko

2018-06-01

In atherosclerosis, vascular smooth muscle cells (VSMC) migrate from the media toward the intima of the arteries in response to cytokines, such as platelet-derived growth factor (PDGF). However, molecular mechanism underlying the PDGF-induced migration of VSMCs remains unclear. The migration of rat aorta-derived synthetic VSMCs, A7r5, in response to PDGF was potently inhibited by a Ca V 1.2 channel inhibitor, nifedipine, and a Src family tyrosine kinase (SFK)/Abl inhibitor, bosutinib, in a less-than-additive manner. PDGF significantly increased Ca V 1.2 channel currents without altering Ca V 1.2 protein expression levels in A7r5 cells. This reaction was inhibited by C-terminal Src kinase, a selective inhibitor of SFKs. In contractile VSMCs, the C-terminus of Ca V 1.2 is proteolytically cleaved into proximal and distal C-termini (PCT and DCT, respectively). Clipped DCT is noncovalently reassociated with PCT to autoinhibit the channel activity. Conversely, in synthetic A7r5 cells, full-length Ca V 1.2 (Ca V 1.2FL) is expressed much more abundantly than truncated Ca V 1.2. In a heterologous expression system, c-Src activated Ca V 1.2 channels composed of Ca V 1.2FL but not truncated Ca V 1.2 (Ca V 1.2Δ1763) or Ca V 1.2Δ1763 plus clipped DCT. Further, c-Src enhanced the coupling efficiency between the voltage-sensing domain and activation gate of Ca V 1.2FL channels by phosphorylating Tyr1709 and Tyr1758 in PCT. Compared with Ca V 1.2Δ1763, c-Src could more efficiently bind to and phosphorylate Ca V 1.2FL irrespective of the presence or absence of clipped DCT. Therefore, in atherosclerotic lesions, phenotypic switching of VSMCs may facilitate pro-migratory effects of PDGF on VSMCs by suppressing posttranslational Ca V 1.2 modifications.

The Utility of 64 Channel Multidetector CT Angiography for Evaluating the Renal Vascular Anatomy and Possible Variations: a Pictorial Essay

Energy Technology Data Exchange (ETDEWEB)

Kumar, Sheo; Neyaz, Zafar; Gupta, Archna [Sanjay Gandhi Post Graduate Institute of Medical Sciences, Lucknow (India)

2010-06-15

The increased use of laparoscopic nephrectomy and nephron-sparing surgery has prompted the need for a more detailed radiological evaluation of the renal vascular anatomy. Multidetector CT angiography is a fast and accurate modality for assessing the precise anatomy of the renal vessels. In this pictorial review, we present the multidetector CT angiography appearances of the normal renal vascular anatomy and a spectrum of various anomalies that require accurate vascular depiction before undergoing surgical treatment.

The utility of 64 channel multidetector CT angiography for evaluating the renal vascular anatomy and possible variations: a pictorial essay.

Science.gov (United States)

Kumar, Sheo; Neyaz, Zafar; Gupta, Archna

2010-01-01

The increased use of laparoscopic nephrectomy and nephron-sparing surgery has prompted the need for a more detailed radiological evaluation of the renal vascular anatomy. Multidetector CT angiography is a fast and accurate modality for assessing the precise anatomy of the renal vessels. In this pictorial review, we present the multidetector CT angiography appearances of the normal renal vascular anatomy and a spectrum of various anomalies that require accurate vascular depiction before undergoing surgical treatment.

The Utility of 64 Channel Multidetector CT Angiography for Evaluating the Renal Vascular Anatomy and Possible Variations: a Pictorial Essay

International Nuclear Information System (INIS)

Kumar, Sheo; Neyaz, Zafar; Gupta, Archna

2010-01-01

The increased use of laparoscopic nephrectomy and nephron-sparing surgery has prompted the need for a more detailed radiological evaluation of the renal vascular anatomy. Multidetector CT angiography is a fast and accurate modality for assessing the precise anatomy of the renal vessels. In this pictorial review, we present the multidetector CT angiography appearances of the normal renal vascular anatomy and a spectrum of various anomalies that require accurate vascular depiction before undergoing surgical treatment

Additive Manufacturing of Vascular Grafts and Vascularized Tissue Constructs.

Science.gov (United States)

Elomaa, Laura; Yang, Yunzhi Peter

2017-10-01

There is a great need for engineered vascular grafts among patients with cardiovascular diseases who are in need of bypass therapy and lack autologous healthy blood vessels. In addition, because of the severe worldwide shortage of organ donors, there is an increasing need for engineered vascularized tissue constructs as an alternative to organ transplants. Additive manufacturing (AM) offers great advantages and flexibility of fabrication of cell-laden, multimaterial, and anatomically shaped vascular grafts and vascularized tissue constructs. Various inkjet-, extrusion-, and photocrosslinking-based AM techniques have been applied to the fabrication of both self-standing vascular grafts and porous, vascularized tissue constructs. This review discusses the state-of-the-art research on the use of AM for vascular applications and the key criteria for biomaterials in the AM of both acellular and cellular constructs. We envision that new smart printing materials that can adapt to their environment and encourage rapid endothelialization and remodeling will be the key factor in the future for the successful AM of personalized and dynamic vascular tissue applications.

Response of Vascular Plant Communities to Harvest in Southern Appalachian Mixed-Oak Forests: Two-Year Results

Science.gov (United States)

Bryan W. Wender; Sharon M. Hood; David W. Smith; Shepard M. Zedaker; David L. Loftis

1999-01-01

A long-term study has been established to monitor the effects of seven silvicultural prescriptions on vascular flora community attributes. Treatments include a control, understory vegetation control, group selection, two levels of shelterwoods, leave-tree, and clearcut. Second growing season. post-treatment results are compared to pre-harvest values for residual~...

Cells exposed to a huntingtin fragment containing an expanded polyglutamine tract show no sign of ion channel formation: results arguing against the ion channel hypothesis

DEFF Research Database (Denmark)

Nørremølle, Anne; Grunnet, Morten; Hasholt, Lis

2003-01-01

Ion channels formed by expanded polyglutamine tracts have been proposed to play an important role in the pathological processes leading to neurodegeneration in Huntington's disease and other CAG repeat diseases. We tested the capacity of a huntingtin fragment containing an expanded polyglutamine...... in the currents recorded in any of the two expression systems, indicating no changes in ion channel activity. The results therefore argue against the proposed hypothesis of expanded polyglutamines forming ion channels....

Single Nisoldipine-Sensitive Calcium Channels in Smooth Muscle Cells Isolated from Rabbit Mesenteric Artery

Science.gov (United States)

Worley, Jennings F.; Deitmer, Joachim W.; Nelson, Mark T.

1986-08-01

Single smooth muscle cells were enzymatically isolated from the rabbit mesenteric artery. At physiological levels of external Ca, these cells were relaxed and contracted on exposure to norepinephrine, caffeine, or high levels of potassium. The patch-clamp technique was used to measure unitary currents through single channels in the isolated cells. Single channels were selective for divalent cations and exhibited two conductance levels, 8 pS and 15 pS. Both types of channels were voltage-dependent, and channel activity occurred at potentials positive to -40 mV. The activity of both channel types was almost completely inhibited by 50 nM nisoldipine. These channels appear to be the pathways for voltage-dependent Ca influx in vascular smooth muscle and may be the targets of the clinically used dihydropyridines.

Effectiveness of quantitative MAA SPECT/CT for the definition of vascularized hepatic volume and dosimetric approach: phantom validation and clinical preliminary results in patients with complex hepatic vascularization treated with yttrium-90-labeled microspheres.

Science.gov (United States)

Garin, Etienne; Lenoir, Laurence; Rolland, Yan; Laffont, Sophie; Pracht, Marc; Mesbah, Habiba; Porée, Philippe; Ardisson, Valérie; Bourguet, Patrick; Clement, Bruno; Boucher, Eveline

2011-12-01

The goal of this study was to assess the use of quantitative single-photon emission computed tomography/computed tomography (SPECT/CT) analysis for vascularized volume measurements in the use of the yttrium-90-radiolabeled microspheres (TheraSphere). A phantom study was conducted for the validation of SPECT/CT volume measurement. SPECT/CT quantitative analysis was used for the measurement of the volume of distribution of the albumin macroaggregates (MAA; i.e., the vascularized volume) in the liver and the tumor, and the total activity contained in the liver and the tumor in four consecutive patients presenting with a complex liver vascularization referred for a treatment with TheraSphere. SPECT/CT volume measurement proved to be accurate (mean error <7%) and reproducible (interobserver concordance 0.99). For eight treatments, in cases of complex hepatic vascularization, the hepatic volumes based on angiography and CT led to a relative overestimation or underestimation of the vascularized hepatic volume by 43.2 ± 32.7% (5-87%) compared with SPECT/CT analyses. The vascularized liver volume taken into account calculated from SPECT/CT data, instead of angiography and CT data, results in modifying the activity injected for three treatments of eight. Moreover, quantitative analysis of SPECT/CT allows us to calculate the absorbed dose in the tumor and in the healthy liver, leading to doubling of the injected activity for one treatment of eight. MAA SPECT/CT is accurate for volume measurements. It provides a valuable contribution to the therapeutic planning of patients presenting with complex hepatic vascularization, in particular for calculating the vascularized liver volume, the activity to be injected and the absorbed doses. Studies should be conducted to assess the role of quantitative MAA/SPECT CT in therapeutic planning.

Increased transient receptor potential canonical type 3 channels in vasculature from hypertensive rats

DEFF Research Database (Denmark)

Liu, Daoyan; Yang, Dachun; He, Hongbo

2009-01-01

We tested the hypothesis that transient receptor potential canonical type 3 (TRPC3) channels are increased in vascular smooth muscle cells and aortic tissue from spontaneously hypertensive rats (SHR) compared with normotensive Wistar Kyoto rats. Expression of TRPC3 was analyzed by immunohistochem...

Pulsatile atheroprone shear stress affects the expression of transient receptor potential channels in human endothelial cells

DEFF Research Database (Denmark)

Thilo, Florian; Vorderwülbecke, Bernd J; Marki, Alex

2012-01-01

in comparison with endothelial cells grown under static conditions. There was a significant association between the expression of TRPC6 and tumor necrosis factor-α mRNA in human vascular tissue. No-flow and atheroprone flow conditions are equally characterized by an increase in the expression of tumor necrosis......The goal of the study was to assess whether pulsatile atheroprone shear stress modulates the expression of transient receptor potential (TRP) channels, TRPC3, TRPC6, TRPM7, and TRPV1 mRNA, in human umbilical vascular endothelial cells. Exposure of cultured vascular endothelial cells to defined...

Double-filter identification of vascular-expressed genes using Arabidopsis plants with vascular hypertrophy and hypotrophy.

Science.gov (United States)

Ckurshumova, Wenzislava; Scarpella, Enrico; Goldstein, Rochelle S; Berleth, Thomas

2011-08-01

Genes expressed in vascular tissues have been identified by several strategies, usually with a focus on mature vascular cells. In this study, we explored the possibility of using two opposite types of altered tissue compositions in combination with a double-filter selection to identify genes with a high probability of vascular expression in early organ primordia. Specifically, we generated full-transcriptome microarray profiles of plants with (a) genetically strongly reduced and (b) pharmacologically vastly increased vascular tissues and identified a reproducible cohort of 158 transcripts that fulfilled the dual requirement of being underrepresented in (a) and overrepresented in (b). In order to assess the predictive value of our identification scheme for vascular gene expression, we determined the expression patterns of genes in two unbiased subsamples. First, we assessed the expression patterns of all twenty annotated transcription factor genes from the cohort of 158 genes and found that seventeen of the twenty genes were preferentially expressed in leaf vascular cells. Remarkably, fifteen of these seventeen vascular genes were clearly expressed already very early in leaf vein development. Twelve genes with published leaf expression patterns served as a second subsample to monitor the representation of vascular genes in our cohort. Of those twelve genes, eleven were preferentially expressed in leaf vascular tissues. Based on these results we propose that our compendium of 158 genes represents a sample that is highly enriched for genes expressed in vascular tissues and that our approach is particularly suited to detect genes expressed in vascular cell lineages at early stages of their inception. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

T cells in vascular inflammatory diseases

Directory of Open Access Journals (Sweden)

Lucas L Lintermans

2014-10-01

Full Text Available Inflammation of the human vasculature is a manifestation of many different diseases ranging from systemic autoimmune diseases to chronic inflammatory diseases, in which multiple types of immune cells are involved. For both autoimmune diseases and chronic inflammatory diseases several observations support a key role for T lymphocytes in these disease pathologies, but the underlying mechanisms are poorly understood. Previous studies in several autoimmune diseases have demonstrated a significant role for a specific subset of CD4+ T cells termed effector memory T cells. This expanded population of effector memory T cells may contribute to tissue injury and disease progression. These cells exert multiple pro-inflammatory functions through the release of effector cytokines. Many of these cytokines have been detected in the inflammatory lesions and participate in the vasculitic reaction, contributing to recruitment of macrophages, neutrophils, dendritic cells, NK cells, B cells and T cells. In addition, functional impairment of regulatory T cells paralyzes anti-inflammatory effects in vasculitic disorders. Interestingly, activation of effector memory T cells in uniquely dependent on the voltage-gated Kv1.3 potassium channel providing an anchor for specific drug targeting. In this review, we focus on the CD4+ T cells in the context of vascular inflammation and describe the evidence supporting the role of different T cell subsets in vascular inflammation. Selective targeting of pathogenic effector memory T cells might enable a more tailored therapeutic approach that avoids unwanted adverse side effects of generalized immunosuppression by modulating the effector functions of T cell responses to inhibit the development of vascular inflammation.

Non-invasive vascular imaging: assessing tumour vascularity

International Nuclear Information System (INIS)

Delorme, S.; Knopp, M.V.

1998-01-01

Non-invasive assessment of vascularity is a new diagnostic approach to characterise tumours. Vascular assessment is based on the pathophysiology of tumour angiogenesis and its diagnostic implications for tumour biology, prognosis and therapy response. Two current techniques investigating vascular features in addition to morphology are Doppler ultrasonography and contrast-enhanced MRI. Diagnostic differentiation has been shown to be possible with Doppler, and a high degree of observed vascularity could be linked to an aggressive course of the disease. Dynamic MRI using gadolinium chelates is already used clinically to detect and differentiate tumours. The histological correlation shows that capillary permeability is increased in malignant tumours and is the best criterion for differentiation from benign processes. Permeability and perfusion factors seem to be more diagnostic than overall vessel density. New clinical applications are currently being established for therapy monitoring. Further instrumental developments will bring harmonic imaging in Doppler, and faster imaging techniques, higher spatial resolution and novel pharmacokinetic concepts in MRI. Upcoming contrast agents for both Doppler and MRI will further improve estimation of intratumoural blood volume and vascular permeability. (orig.)

The Effect of Vascular Neuropathology on Late-life Cognition: Results from the SMART Project.

Science.gov (United States)

Kryscio, R J; Abner, E L; Nelson, P T; Bennett, D; Schneider, J; Yu, L; Hemmy, L S; Lim, K O; Masaki, K; Cairns, N; Xiong, C; Woltjer, R; Dodge, H H; Tyas, S; Fardo, D W; Lou, W; Wan, L; Schmitt, F A

2016-06-01

Cerebral vascular pathology may contribute to cognitive decline experienced by some elderly near death. Given evidence for mixed neuropathologies in advanced age, preventing or reducing cerebrovascular burden in late life may be beneficial. To correlate measures of cerebral vascular pathology with cognitive trajectories. Observational study. A cohort of 2,274 individuals who came to autopsy at a mean age of 89.3 years and 82 percent of whom had at least two cognitive assessments within the last six years of life was compiled from six centers conducting longitudinal studies. For each cognitive domain: immediate and delayed memory, language, and naming, three trajectories were examined: good, intermediate, and poor cognition. The probability of a participant belonging to each trajectory was associated with measures of cerebral vascular pathology after adjustment for demographics, APOE, and Alzheimer neuropathology. A large proportion of the cohort (72-94%) experienced good or intermediate cognition in the four domains examined. The presence of arteriolosclerosis and the presence of lacunar infarcts doubled the odds of belonging to the poor cognitive trajectory for language when compared to the good trajectory. The presence of lacunar infarcts increased the odds of an intermediate or poor trajectory for immediate and delayed recall while the presence of large artery infarcts increased the odds of poor trajectories for all four cognitive domains examined. Microinfarcts and cerebral amyloid angiopathy had little effect on the trajectories. Indicators of cerebral vascular pathology act differently on late life cognition.

Portal vein embolization using the Amplatzer vascular plug II. Preliminary results

International Nuclear Information System (INIS)

Libicher, Martin; Herbrik, M.; Poggenborg, J.; Bovenschulte, H.; Schwabe, H.; Stippel, D.

2010-01-01

Purpose: In this study we examined the feasibility of portal vein embolization (PVE) by using the Amplatzer Vascular Plug (AVP-II). We measured the time of vessel occlusion after plug deployment and changes in plug length and diameter within 4 weeks of PVE. Materials and Methods: in 10 consecutive patients (4 women, age 64 ± 10 yrs, 48 - 82 yrs) an ipsilateral PVE of the right portal vein was performed prior to intended hemihepatectomy. After embolization with microparticles, the right portal vein was occluded using an AVP-II. We measured the time of complete vessel occlusion by angiography. Follow-up with computed tomography (CT) was performed within 72h and after 4 weeks. Results: PVE was performed in all 10 patients without acute complications. Complete vessel occlusion was achieved in 9.7 ± 5.1 min (range 1 - 21 min). On follow-up CT we found enhanced arterial vascularization of the embolized liver segments in 5/5 patients within 72 hours and in 6/10 patients after 4 weeks. The plug showed a contraction of 20 ± 9% and a dilatation of 23 ± 13%. Thus, the AVP-II dilated to 94 ± 8% (78 - 100%) of its nominal diameter. The plug diameter was significantly larger in men compared to women (17 ± 1.7 mm vs. 14 ± 1.4 mm, p < 0.02). We did not observe any recanalization or migration of the device. The volume of the left liver lobe increased significantly by 27% (p < 0.001) after 4 weeks. Conclusion: PVE with the AVP-II is a feasible and effective method. The AVP-II can dilate within 4 weeks up to its nominal diameter dependent on the grade of oversizing. Dilatation of the diameter is associated with a shortening in length. (orig.)

Effects of river restoration on riparian biodiversity in secondary channels of the Pite River, Sweden.

Science.gov (United States)

Helfield, James M; Engström, Johanna; Michel, James T; Nilsson, Christer; Jansson, Roland

2012-01-01

Between 1850 and 1970, rivers throughout Sweden were channelized to facilitate timber floating. Floatway structures were installed to streamline banks and disconnect flow to secondary channels, resulting in simplified channel morphologies and more homogenous flow regimes. In recent years, local authorities have begun to restore channelized rivers. In this study, we examined the effects of restoration on riparian plant communities at previously disconnected secondary channels of the Pite River. We detected no increase in riparian diversity at restored sites relative to unrestored (i.e., disconnected) sites, but we did observe significant differences in species composition of both vascular plant and bryophyte communities. Disconnected sites featured greater zonation, with mesic-hydric floodplain species represented in plots closest to the stream and mesic-xeric upland species represented in plots farthest from the stream. In contrast, restored sites were most strongly represented by upland species at all distances relative to the stream. These patterns likely result from the increased water levels in reconnected channels where, prior to restoration, upland plants had expanded toward the stream. Nonetheless, the restored fluvial regime has not brought about the development of characteristic flood-adapted plant communities, probably due to the short time interval (ca. 5 years) since restoration. Previous studies have demonstrated relatively quick responses to similar restoration in single-channel tributaries, but secondary channels may respond differently due to the more buffered hydrologic regimes typically seen in anabranching systems. These findings illustrate how restoration outcomes can vary according to hydrologic, climatic and ecological factors, reinforcing the need for site-specific restoration strategies.

Diabetes and Retinal Vascular Dysfunction

Directory of Open Access Journals (Sweden)

Eui Seok Shin

2014-01-01

Full Text Available Diabetes predominantly affects the microvascular circulation of the retina resulting in a range of structural changes unique to this tissue. These changes ultimately lead to altered permeability, hyperproliferation of endothelial cells and edema, and abnormal vascularization of the retina with resulting loss of vision. Enhanced production of inflammatory mediators and oxidative stress are primary insults with significant contribution to the pathogenesis of diabetic retinopathy (DR. We have determined the identity of the retinal vascular cells affected by hyperglycemia, and have delineated the cell autonomous impact of high glucose on function of these cells. We discuss some of the high glucose specific changes in retinal vascular cells and their contribution to retinal vascular dysfunction. This knowledge provides novel insight into the molecular and cellular defects contributing to the development and progression of diabetic retinopathy, and will aid in the development of innovative, as well as target specific therapeutic approaches for prevention and treatment of DR.

Vasculo-Neuronal Coupling: Retrograde Vascular Communication to Brain Neurons.

Science.gov (United States)

Kim, Ki Jung; Ramiro Diaz, Juan; Iddings, Jennifer A; Filosa, Jessica A

2016-12-14

Continuous cerebral blood flow is essential for neuronal survival, but whether vascular tone influences resting neuronal function is not known. Using a multidisciplinary approach in both rat and mice brain slices, we determined whether flow/pressure-evoked increases or decreases in parenchymal arteriole vascular tone, which result in arteriole constriction and dilation, respectively, altered resting cortical pyramidal neuron activity. We present evidence for intercellular communication in the brain involving a flow of information from vessel to astrocyte to neuron, a direction opposite to that of classic neurovascular coupling and referred to here as vasculo-neuronal coupling (VNC). Flow/pressure increases within parenchymal arterioles increased vascular tone and simultaneously decreased resting pyramidal neuron firing activity. On the other hand, flow/pressure decreases evoke parenchymal arteriole dilation and increased resting pyramidal neuron firing activity. In GLAST-CreERT2; R26-lsl-GCaMP3 mice, we demonstrate that increased parenchymal arteriole tone significantly increased intracellular calcium in perivascular astrocyte processes, the onset of astrocyte calcium changes preceded the inhibition of cortical pyramidal neuronal firing activity. During increases in parenchymal arteriole tone, the pyramidal neuron response was unaffected by blockers of nitric oxide, GABA A , glutamate, or ecto-ATPase. However, VNC was abrogated by TRPV4 channel, GABA B , as well as an adenosine A 1 receptor blocker. Differently to pyramidal neuron responses, increases in flow/pressure within parenchymal arterioles increased the firing activity of a subtype of interneuron. Together, these data suggest that VNC is a complex constitutive active process that enables neurons to efficiently adjust their resting activity according to brain perfusion levels, thus safeguarding cellular homeostasis by preventing mismatches between energy supply and demand. We present evidence for vessel

Geomorphic changes resulting from floods in reconfigured gravel-bed river channels in Colorado, USA

Science.gov (United States)

Elliott, J.G.; Capesius, J.P.

2009-01-01

Geomorphic changes in reconfi gured reaches of three Colorado rivers in response to floods in 2005 provide a benchmark for "restoration" assessment. Sedimententrainment potential is expressed as the ratio of the shear stress from the 2 yr, 5 yr, 10 yr, and 2005 floods to the critical shear stress for sediment. Some observed response was explained by the excess of flood shear stress relative to the resisting force of the sediment. Bed-load entrainment in the Uncompahgre River and the North Fork Gunnison River, during 4 and 6 yr floods respectively, resulted in streambed scour, streambed deposition, lateral-bar accretion, and channel migration at various locations. Some constructed boulder and log structures failed because of high rates of bank erosion or bed-material deposition. The Lake Fork showed little or no net change after the 2005 flood; however, this channel had not conveyed floods greater than the 2.5 yr flood since reconfi guration. Channel slope and the 2 yr flood, a surrogate for bankfull discharge, from all three reconfi gured reaches plotted above the Leopold and Wolman channel-pattern threshold in the "braided channel" region, indicating that braiding, rather than a single-thread meandering channel, and midchannel bar formation may be the natural tendency of these gravel-bed reaches. When plotted against a total stream-power and median-sediment-size threshold for the 2 yr flood, however, the Lake Fork plotted in the "single-thread channel" region, the North Fork Gunnison plotted in the " multiplethread" region, and the Uncompahgre River plotted on the threshold. All three rivers plotted in the multiple-thread region for floods of 5 yr recurrence or greater. ?? 2009 Geological Society of America.

Activation of K+ channels and Na+/K+ ATPase prevents aortic endothelial dysfunction in 7-day lead-treated rats

International Nuclear Information System (INIS)

Fiorim, Jonaina; Ribeiro Júnior, Rogério Faustino; Azevedo, Bruna Fernades; Simões, Maylla Ronacher; Padilha, Alessandra Simão; Stefanon, Ivanita; Alonso, Maria Jesus; Salaices, Mercedes; Vassallo, Dalton Valentim

2012-01-01

Seven day exposure to a low concentration of lead acetate increases nitric oxide bioavailability suggesting a putative role of K + channels affecting vascular reactivity. This could be an adaptive mechanism at the initial stages of toxicity from lead exposure due to oxidative stress. We evaluated whether lead alters the participation of K + channels and Na + /K + -ATPase (NKA) on vascular function. Wistar rats were treated with lead (1st dose 4 μg/100 g, subsequent doses 0.05 μg/100 g, im, 7 days) or vehicle. Lead treatment reduced the contractile response of aortic rings to phenylephrine (PHE) without changing the vasodilator response to acetylcholine (ACh) or sodium nitroprusside (SNP). Furthermore, this treatment increased basal O 2 − production, and apocynin (0.3 μM), superoxide dismutase (150 U/mL) and catalase (1000 U/mL) reduced the response to PHE only in the treated group. Lead also increased aortic functional NKA activity evaluated by K + -induced relaxation curves. Ouabain (100 μM) plus L-NAME (100 μM), aminoguanidine (50 μM) or tetraethylammonium (TEA, 2 mM) reduced the K + -induced relaxation only in lead-treated rats. When aortic rings were precontracted with KCl (60 mM/L) or preincubated with TEA (2 mM), 4-aminopyridine (4-AP, 5 mM), iberiotoxin (IbTX, 30 nM), apamin (0.5 μM) or charybdotoxin (0.1 μM), the ACh-induced relaxation was more reduced in the lead-treated rats. Additionally, 4-AP and IbTX reduced the relaxation elicited by SNP more in the lead-treated rats. Results suggest that lead treatment promoted NKA and K + channels activation and these effects might contribute to the preservation of aortic endothelial function against oxidative stress. -- Highlights: ► Increased free radicals production ► Increased Na + /K + ATPase activity ► Promotes activation of the K + channels and reduced vascular reactivity ► These effects preserve endothelial function against oxidative stress. ► Low concentrations constitute environmental

[Groin abscesses and vascular catastrophes in intravenous drug users--strategy and results].

Science.gov (United States)

Scheuerlein, H; Ruff, S; Haage, P; Zirngibl, H; Fraunhofer, S; Settmacher, U

2008-02-01

Drug addiction is a global medical and public health-care problem. Infections of the groin and fossa cubitalis are a common clinical problem in these patients. Severe vascular complications are rare but if they occur, therapy is difficult and requires emergency management and surgery because of bleeding problems. In a retrospective case series, we report on patients treated within an emergency setting in our hospital because of groin abscesses with vascular involvement between 2003 and 2006. The therapeutic concepts and results are reported and discussed in the context of a review of the international literature. We report on 4 patients with a long-standing history of i. v. drug abuse (average age 33, range 29-36 years). All were hepatitis C Ag positive and HIV negative. The general health and nutritional status were not compromised, all patients had one or more DVT in their medical history. In two cases, emergency surgery with revascularisation was necessary (after 2 days in one case and 4 weeks in the other) because of septic bleeding subsequent to abscess incision. Two patients underwent primary revascularisation because of pseudoaneurysms. The grafts were a saphenous vein patch and a superficial femoral artery patch in one and deep vein segments in two cases. In two cases, a sartorius muscle flap and VAC therapy were used to cover the defect. All patients survived, minor amputation became necessary in one case. Abscess excision and debridement have to be as complete as possible and primary revascularisation is the procedure of choice in cases of severe groin infection. In the case of large vessel involvement, abscess incision alone without revision of the vascular structures is dangerous because of subsequent complications like secondary ruptures. For this reason, these patients require intensive care and close monitoring. Successful treatment exclusively based on ligation is described in literature with regard to isolated lesions of the superficial or deep

[G-protein potentiates the activation of TNF-alpha on calcium-activated potassium channel in ECV304].

Science.gov (United States)

Lin, L; Zheng, Y; Qu, J; Bao, G

2000-06-01

Observe the effect of tumor necrosis factor-alpha (TNF-alpha) on calcium-activated potassium channel in ECV304 and the possible involvement of G-protein mediation in the action of TNF-alpha. Using the cell-attached configuration of patch clamp technique. (1) the activity of high-conductance calcium-activated potassium channel (BKca) was recorded. Its conductance is (202.54 +/- 16.62) pS; (2) the activity of BKca was potentiated by 200 U/ml TNF-alpha; (3) G-protein would intensify this TNF-alpha activation. TNF-alpha acted on vascular endothelial cell ECV304 could rapidly activate the activity of BKca. Opening of BKca resulted in membrane hyper-polarization which could increase electro-chemical gradient for the resting Ca2+ influx and open leakage calcium channel, thus resting cytoplasmic free Ca2+ concentration could be elevated. G-protein may exert an important regulation in this process.

Overview of vascular disease

International Nuclear Information System (INIS)

Bisset, G.S. III

1998-01-01

Vascular disease in the pediatric population is a poorly understood process which is often underestimated in its incidence. The common beginnings of such ubiquitous diseases as atherosclerosis manifest themselves at a cellular level shortly after birth. Other common systemic disorders, including congestive heart failure and sepsis, are also intricately associated with dysfunctional vasculature. Progress in the understanding of normal and pathophysiologic processes within the vascular system begins with the 'control center' - the endothelial cell. The purpose of this review is to consolidate a body of knowledge on the processes that occur at the cellular level within the blood vessel wall, and to simplify the understanding of how imbalances in these physiologic parameters result in vascular disease. (orig.)

Channels Coordination Game Model Based on Result Fairness Preference and Reciprocal Fairness Preference: A Behavior Game Forecasting and Analysis Method

OpenAIRE

Ding, Chuan; Wang, Kaihong; Huang, Xiaoying

2014-01-01

In a distribution channel, channel members are not always self-interested, but altruistic in some conditions. Based on this assumption, this paper adopts a behavior game method to analyze and forecast channel members’ decision behavior based on result fairness preference and reciprocal fairness preference by embedding a fair preference theory in channel research of coordination. The behavior game forecasts that a channel can achieve coordination if channel members consider behavior elemen...

Rapid diagnosis and treatment of TIA results in low rates of stroke, myocardial infarction and vascular death.

Science.gov (United States)

Cocho, D; Monell, J; Planells, G; Ricciardi, A C; Pons, J; Boltes, A; Espinosa, J; Ayats, M; Garcia, N; Otermin, P

2016-01-01

The 90-day risk of cerebral infarction in patients with transient ischaemic attack (TIA) is estimated at between 8% and 20%. There is little consensus as to which diagnostic strategy is most effective. This study evaluates the benefits of early transthoracic echocardiography (TTE) with carotid and transcranial Doppler ultrasound in patients with TIA. Prospective study of patients with TIA in an emergency department setting. Demographic data, vascular risk factors, and ABCD(2) score were analysed. TIA aetiology was classified according to TOAST criteria. All patients underwent early vascular studies (TIA, myocardial infarction (MI), or vascular death during the first year. We evaluated 92 patients enrolled over 24 months. Mean age was 68.3±13 years and 61% were male. The mean ABCD(2) score was 3 points (≥5 in 30%). The distribution of TIA subtypes was as follows: 12% large-artery atherosclerosis; 30% cardioembolism; 10% small-vessel occlusion; 40% undetermined cause; and 8% rare causes. Findings from the early TTE led to a change in treatment strategy in 6 patients (6.5%) who displayed normal physical examination and ECG findings. At one year of follow-up, 3 patients had experienced stroke (3.2%) and 1 patient experienced MI (1%); no vascular deaths were identified. In our TIA patients, early vascular study and detecting patients with silent cardiomyopathy may have contributed to the low rate of vascular disease recurrence. Copyright © 2014 Sociedad Española de Neurología. Published by Elsevier España, S.L.U. All rights reserved.

Mid-term clinical results of tissue-engineered vascular autografts

International Nuclear Information System (INIS)

Matsumura, Goki; Shin'oka, Toshiharu; Hibino, Narutoshi; Saito, Satoshi; Sakamoto, Takahiko; Ichihara, Yuki; Hobo, Kyoko; Miyamoto, Shin'ka; Kurosawa, Hiromi

2007-01-01

Prosthetic and bioprosthetic materials currently in use lack growth potential and therefore must be repeatedly replaced in pediatric patients as they grow. Tissue engineering is a new discipline that offers the potential for creating replacement structures from autologous cells and biodegradable polymer scaffolds. In May 2000, we initiated clinical application of tissue-engineered vascular grafts seeded with cultured cells. However, cell culturing is time-consuming, and xenoserum must be used. To overcome these disadvantages, we began to use bone marrow cells, readily available on the day of surgery, as a cell source. Since September 2001, tissue-engineered grafts seeded with autologous bone marrow cells have been implanted in 44 patients. The patients or their parents were fully informed and had given consent to the procedure. A 3 to 10 ml/kg specimen of bone marrow was aspirated with the patient under general anesthesia before the skin incision. The polymer tube serving as a scaffold for the cells was composed of a copolymer of lactide and ε-caprolactone (50:50) which degrades by hydrolysis. Polyglycolic or poly-l-lactic acid woven fabric was used for reinforcement. Twenty-six tissue-engineered conduits and 19 tissue-engineered patches were used for the repair of congenital heart defects. The patients' ages ranged from 1 to 24 years (median 7.4 years). All patients underwent a catheterization study, CT scan, or both, for evaluation after the operation. There were 4 late deaths due to heart failure with or without multiple organ failure or brain bleeding in this series; these were unrelated to the tissue-engineered graft function. One patient required percutaneous balloon angioplasty for tubular graft-stenosis and 4 patients for the stenosis of the patch-shaped tissue engineered material. Two patients required re-do operation; one for recurrent pulmonary stenosis and another for a resulting R-L shunt after the lateral tunnel method. Kaplan-Meier analysis in

Dual channel photoplethysmography studies of cardio-vascular response to the body position changes

Science.gov (United States)

Erts, R.; Kukulis, I.; Spigulis, J.; Kere, L.

2005-08-01

The dual-channel photoplethysmography studies of physiological responses during 3-stage orthostatic test were performed. Clear differences in heartbeat rate, pulse wave transit time and blood pressure variations of healthy volunteers and diabetic patients have been observed.

Molecular studies of BKCa channels in intracranial arteries: presence and localization

DEFF Research Database (Denmark)

Johansson, Helle Wulf; Hay-Schmidt, Anders; Poulsen, Asser Nyander

2008-01-01

of the BK(Ca) channel in rat basilar, middle cerebral, and middle meningeal arteries by reverse transcription polymerase chain reaction (RT-PCR), quantitative real-time PCR, and Western blotting. Distribution patterns were investigated using in situ hybridization and immunofluorescence studies. RT......Large conductance calcium-activated potassium channels (BK(ca)) are crucial for the regulation of cerebral vascular basal tone and might be involved in cerebral vasodilation relevant to migraine and stroke. We studied the differential gene expression of mRNA transcript levels and protein expression......-PCR and quantitative real-time PCR detected the expression of the BK(Ca) channel mRNA transcript in rat basilar, middle cerebral, and middle meningeal arteries, with the transcript being expressed more abundantly in rat basilar arteries than in middle cerebral and middle meningeal arteries. Western blotting detected...

Hypothenar hammer syndrome: long-term results of vascular reconstruction.

Science.gov (United States)

Endress, Ryan D; Johnson, Craig H; Bishop, Allen T; Shin, Alexander Y

2015-04-01

To evaluate long-term patency rates and related outcomes after vascular reconstruction of hypothenar hammer syndrome and identify patient- or treatment-related factors that may contribute to differences in outcome. We used color flow ultrasound to determine the patency of 18 vein graft reconstructions of the ulnar artery at the wrist in 16 patients. Validated questionnaires evaluated patients' functional disability with the Disabilities of the Arm, Shoulder, and Hand score, pain with the visual analog scale, and cold intolerance with the Cold Intolerance Symptom Severity survey. Patient demographics, clinical data, and surgical factors were analyzed for association with graft failure. Patients were asked to grade the result of treatment on a scale of 0 to 10. Of 18 grafts, 14 (78%) were occluded at a mean of 118 months postoperatively. Patients with patent grafts had significantly less disability related to cold intolerance according to the Cold Intolerance Symptom Severity survey in addition to significantly less pain on the visual analog scale. There was no statistical difference in Disabilities of the Arm, Shoulder, and Hand scores between patients with patent or occluded grafts. Patients graded the result significantly higher in patent reconstructions. We noted a higher incidence of graft occlusion than previously reported at a mean follow-up of 9.8 years, which represents a long-duration follow-up study of surgical treatment of hypothenar hammer syndrome. Despite a high percentage of occlusion, overall, patients remained satisfied with low functional disability and all would recommend surgical reconstruction. This study suggests that improved outcomes may result from patent grafts in the long term. Prognostic IV. Copyright © 2015 American Society for Surgery of the Hand. Published by Elsevier Inc. All rights reserved.

COMMISSIONING AND FIRST RESULTS FROM CHANNELING RADIATION AT FAST

Energy Technology Data Exchange (ETDEWEB)

Halavanau, A. [NIU, DeKalb; Mihalcea, D. [NIU, DeKalb; Broemmelsiek, D. [Fermilab; Edstrom, D. [Fermilab; Sen, T. [Fermilab; Romanov, A. [Fermilab; Ruan, J. [Fermilab; Shiltsev, V. [Fermilab; Kobak, P. [BYU-I; Rush, W. [Kansas U.; Hyun, J. [Tsukuba, Graduate U. Adv. Studies

2016-10-18

X-rays have widespread applications in science and industry, but developing a simple, compact, and high-quality X-ray source remains a challenge. Our collaboration has explored the possible use of channeling radiation driven by a 50 MeV low-emittance electron beam to produce narrowband hard X-rays with photon energy of 40 to 140 keV [8,9,11]. Here we present the simulated X-ray spectra including the background bremsstrahlung contribution, and a description of the required optimization of the relevant electron-beam parameters necessary to maximize brilliance of the resulting X-ray beam. Results are presented from our test of this, carried out at the Fermilab Accelerator Science & Technology (FAST) facility’s 50-MeV low-energy electron injector. As a result of the beam parameters, made possible by the photo-injector based SRF linac, the average brilliance at FAST was expected to be about one order of magnitude higher than that in previous experiments.

Channel flow and trichloroethylene treatment in a partly iron-filled fracture: Experimental and model results

Science.gov (United States)

Cai, Zuansi; Merly, Corrine; Thomson, Neil R.; Wilson, Ryan D.; Lerner, David N.

2007-08-01

Technical developments have now made it possible to emplace granular zero-valent iron (Fe 0) in fractured media to create a Fe 0 fracture reactive barrier (Fe 0 FRB) for the treatment of contaminated groundwater. To evaluate this concept, we conducted a laboratory experiment in which trichloroethylene (TCE) contaminated water was flushed through a single uniform fracture created between two sandstone blocks. This fracture was partly filled with what was intended to be a uniform thickness of iron. Partial treatment of TCE by iron demonstrated that the concept of a Fe 0 FRB is practical, but was less than anticipated for an iron layer of uniform thickness. When the experiment was disassembled, evidence of discrete channelised flow was noted and attributed to imperfect placement of the iron. To evaluate the effect of the channel flow, an explicit Channel Model was developed that simplifies this complex flow regime into a conceptualised set of uniform and parallel channels. The mathematical representation of this conceptualisation directly accounts for (i) flow channels and immobile fluid arising from the non-uniform iron placement, (ii) mass transfer from the open fracture to iron and immobile fluid regions, and (iii) degradation in the iron regions. A favourable comparison between laboratory data and the results from the developed mathematical model suggests that the model is capable of representing TCE degradation in fractures with non-uniform iron placement. In order to apply this Channel Model concept to a Fe 0 FRB system, a simplified, or implicit, Lumped Channel Model was developed where the physical and chemical processes in the iron layer and immobile fluid regions are captured by a first-order lumped rate parameter. The performance of this Lumped Channel Model was compared to laboratory data, and benchmarked against the Channel Model. The advantages of the Lumped Channel Model are that the degradation of TCE in the system is represented by a first

Differential expression of T- and L-type voltage-dependent calcium channels in renal resistance vessels

DEFF Research Database (Denmark)

Hansen, Pernille B. Lærkegaard; Jensen, Boye L.; Andreasen, D

2001-01-01

The distribution of voltage-dependent calcium channels in kidney pre- and postglomerular resistance vessels was determined at the molecular and functional levels. Reverse transcription-polymerase chain reaction analysis of microdissected rat preglomerular vessels and cultured smooth muscle cells...... on vascular diameter in the afferent arteriole. We conclude that voltage-dependent L- and T-type calcium channels are expressed and of functional significance in renal cortical preglomerular vessels, in juxtamedullary efferent arterioles, and in outer medullary vasa recta, but not in cortical efferent...

Luteolin Ameliorates Hypertensive Vascular Remodeling through Inhibiting the Proliferation and Migration of Vascular Smooth Muscle Cells

Directory of Open Access Journals (Sweden)

Jie Su

2015-01-01

Full Text Available Objectives. Preliminary researches showed that luteolin was used to treat hypertension. However, it is still unclear whether luteolin has effect on the hypertensive complication such as vascular remodeling. The present study was designed to investigate the effect of luteolin on the hypertensive vascular remodeling and its molecular mechanism. Method and Results. We evaluated the effect of luteolin on aorta thickening of hypertension in spontaneous hypertensive rats (SHRs and found that luteolin could significantly decrease the blood pressure and media thickness of aorta in vivo. Luteolin could inhibit angiotensin II- (Ang II- induced proliferation and migration of vascular smooth muscle cells (VSMCs. Dichlorofluorescein diacetate (DCFH-DA staining result showed that luteolin reduced Ang II-stimulated ROS production in VSMCs. Furthermore, western blot and gelatin zymography results showed that luteolin treatment leaded to a decrease in ERK1/2, p-ERK1/2, p-p38, MMP2, and proliferating cell nuclear antigen (PCNA protein level. Conclusion. These data support that luteolin can ameliorate hypertensive vascular remodeling by inhibiting the proliferation and migration of Ang II-induced VSMCs. Its mechanism is mediated by the regulation of MAPK signaling pathway and the production of ROS.

Lung irradiation induces pulmonary vascular remodelling resembling pulmonary arterial hypertension

NARCIS (Netherlands)

Ghobadi, G.; Bartelds, B.; van der Veen, S. J.; Dickinson, M. G.; Brandenburg, S.; Berger, R. M. F.; Langendijk, J. A.; Coppes, R. P.; van Luijk, P.

Background Pulmonary arterial hypertension (PAH) is a commonly fatal pulmonary vascular disease that is often diagnosed late and is characterised by a progressive rise in pulmonary vascular resistance resulting from typical vascular remodelling. Recent data suggest that vascular damage plays an

Retinal vascular segmentation using superpixel-based line operator and its application to vascular topology estimation.

Science.gov (United States)

Na, Tong; Xie, Jianyang; Zhao, Yitian; Zhao, Yifan; Liu, Yue; Wang, Yongtian; Liu, Jiang

2018-05-09

Automatic methods of analyzing of retinal vascular networks, such as retinal blood vessel detection, vascular network topology estimation, and arteries/veins classification are of great assistance to the ophthalmologist in terms of diagnosis and treatment of a wide spectrum of diseases. We propose a new framework for precisely segmenting retinal vasculatures, constructing retinal vascular network topology, and separating the arteries and veins. A nonlocal total variation inspired Retinex model is employed to remove the image intensity inhomogeneities and relatively poor contrast. For better generalizability and segmentation performance, a superpixel-based line operator is proposed as to distinguish between lines and the edges, thus allowing more tolerance in the position of the respective contours. The concept of dominant sets clustering is adopted to estimate retinal vessel topology and classify the vessel network into arteries and veins. The proposed segmentation method yields competitive results on three public data sets (STARE, DRIVE, and IOSTAR), and it has superior performance when compared with unsupervised segmentation methods, with accuracy of 0.954, 0.957, and 0.964, respectively. The topology estimation approach has been applied to five public databases (DRIVE,STARE, INSPIRE, IOSTAR, and VICAVR) and achieved high accuracy of 0.830, 0.910, 0.915, 0.928, and 0.889, respectively. The accuracies of arteries/veins classification based on the estimated vascular topology on three public databases (INSPIRE, DRIVE and VICAVR) are 0.90.9, 0.910, and 0.907, respectively. The experimental results show that the proposed framework has effectively addressed crossover problem, a bottleneck issue in segmentation and vascular topology reconstruction. The vascular topology information significantly improves the accuracy on arteries/veins classification. © 2018 American Association of Physicists in Medicine.

Touch, Tension, and Transduction – the Function and Regulation of Piezo Ion Channels

Science.gov (United States)

Wu, Jason; Lewis, Amanda; Grandl, Jörg

2016-01-01

In 2010, two proteins, Piezo1 and Piezo2, were identified as the long-sought molecular carriers of an excitatory mechanically activated current found in many cells. This discovery has opened the floodgates for studying a vast number of mechanotransduction processes. Over the past six years, groundbreaking research has identified Piezos as ion channels that sense light touch, proprioception, and vascular blood flow, ruled out roles for Piezos in several other mechanotransduction processes, and revealed the basic structural and functional properties of the channel. Here, we review these findings and discuss the many aspects of Piezo function that remain mysterious, including how Piezos convert a variety of mechanical stimuli into channel activation and subsequent inactivation, and what molecules and mechanisms modulate Piezo function. PMID:27743844

Touch, Tension, and Transduction - The Function and Regulation of Piezo Ion Channels.

Science.gov (United States)

Wu, Jason; Lewis, Amanda H; Grandl, Jörg

2017-01-01

In 2010, two proteins, Piezo1 and Piezo2, were identified as the long-sought molecular carriers of an excitatory mechanically activated current found in many cells. This discovery has opened the floodgates for studying a vast number of mechanotransduction processes. Over the past 6 years, groundbreaking research has identified Piezos as ion channels that sense light touch, proprioception, and vascular blood flow, ruled out roles for Piezos in several other mechanotransduction processes, and revealed the basic structural and functional properties of the channel. Here, we review these findings and discuss the many aspects of Piezo function that remain mysterious, including how Piezos convert a variety of mechanical stimuli into channel activation and subsequent inactivation, and what molecules and mechanisms modulate Piezo function. Copyright © 2016 Elsevier Ltd. All rights reserved.

Ethanol modulation of mammalian BK channels in excitable tissues: molecular targets and their possible contribution to alcohol-induced altered behavior

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Alex M. Dopico

2014-12-01

Full Text Available In most tissues, the function of calcium- and voltage-gated potassium (BK channels is modified in response to ethanol concentrations reached in human blood during alcohol intoxication. In general, modification of BK current from ethanol-naïve preparations in response to brief ethanol exposure results from changes in channel open probability without modification of unitary conductance or change in BK protein levels in the membrane. Protracted and/or repeated ethanol exposure, however, may evoke changes in BK expression. The final ethanol effect on BK open probability leading to either BK current potentiation or BK current reduction is determined by an orchestration of molecular factors, including levels of activating ligand (cytosolic calcium, BK subunit composition and posttranslational modifications, and the channel’s lipid microenvironment. These factors seem to allosterically regulate a direct interaction between ethanol and a recognition pocket of discrete dimensions recently mapped to the channel-forming (slo1 subunit. Type of ethanol exposure also plays a role in the final BK response to the drug: in several central nervous system regions (e.g., striatum, primary sensory neurons, and supraoptic nucleus, acute exposure to ethanol reduces neuronal excitability by enhancing BK activity. In contrast, protracted or repetitive ethanol administration may alter BK subunit composition and membrane expression, rendering the BK complex insensitive to further ethanol exposure. In neurohypophysial axon terminals, ethanol potentiation of BK channel activity leads to a reduction in neuropeptide release. In vascular smooth muscle, however, ethanol inhibition of BK current leads to cell contraction and vascular constriction.

Angiogenesis, Cancer, and Vascular Aging

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Junji Moriya

2017-10-01

Full Text Available Several lines of evidence have revealed that the angiogenic response to ischemic injury declines with age, which might account for the increased morbidity and mortality of cardiovascular disease (CVD among the elderly. While impairment of angiogenesis with aging leads to delayed wound healing or exacerbation of atherosclerotic ischemic diseases, it also inhibits the progression of cancer. Age-related changes of angiogenesis have been considered to at least partly result from vascular aging or endothelial cell senescence. There is considerable evidence supporting the hypothesis that vascular cell senescence contributes to the pathogenesis of age-related CVD, suggesting that vascular aging could be an important therapeutic target. Since therapeutic angiogenesis is now regarded as a promising concept for patients with ischemic CVD, it has become even more important to understand the detailed molecular mechanisms underlying impairment of angiogenesis in older patients. To improve the usefulness of therapeutic angiogenesis, approaches are needed that can compensate for impaired angiogenic capacity in the elderly while not promoting the development or progression of malignancy. In this review, we briefly outline the mechanisms of angiogenesis and vascular aging, followed by a description of how vascular aging leads to impairment of angiogenesis. We also examine potential therapeutic approaches that could enhance angiogenesis and/or vascular function in the elderly, as well as discussing the possibility of anti-senescence therapy or reversal of endothelial cell senescence.

Backscattering study and theoretical investigation of planar channeling processes. I. Experimental results

International Nuclear Information System (INIS)

Abel, F.; Amsel, G.; Bruneaux, M.; Cohen, C.; L'Hoir, A.

1975-01-01

Backscattering experiments in planar channeling have been performed on iron single crystals with 1.9-MeV 4 He beams; these conditions having been chosen for optimal study of the structure of the spectra. Both for the (110) and (100) planes five equally spaced yield maxima are clearly resolved, the maxima damping out at lower energies. Spectra were also registered at various angles of incidence phi 0 with respect to the planes. Yield maxima are observed up to values of phi 0 twice the half-width at half-minimum psi 1 / 2 of an angular scan across the plane psi 1 / 2 =18' for the (110) plane. Except for the first two peaks, these maxima have the same spacing as in the aligned spectrum. They appear to be due to particles belonging to a well-defined transverse energy interval. The mean stopping power for these particles is close to the random stopping power and the mean half-wavelength of their oscillating trajectories in the planar channels calculated from the results is lambda=380 A for the (110) plane and lambda=320 A for the (100) plane. For phi 0 >1.2psi 1 / 2 , the yield on the first maximum is greater than the random yield, reaching approx.1.6 times the latter for 1.4psi 1 / 2 0 1 / 2 . The shoulder effect in the angular scans, as observed for various depths, is clearly related to the yield maxima and hence depends strongly on the position and width of the depth interval chosen. The meaning and validity of the assumption of statistical equilibrium for planar channeled particles are discussed in light of the results

Renal posttransplant's vascular complications

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Bašić Dragoslav

2003-01-01

Full Text Available INTRODUCTION Despite high graft and recipient survival figures worldwide today, a variety of technical complications can threaten the transplant in the postoperative period. Vascular complications are commonly related to technical problems in establishing vascular continuity or to damage that occurs during donor nephrectomy or preservation [13]. AIM The aim of the presenting study is to evaluate counts and rates of vascular complications after renal transplantation and to compare the outcome by donor type. MATERIAL AND METHODS A total of 463 kidneys (319 from living related donor LD and 144 from cadaveric donor - CD were transplanted during the period between June 1975 and December 1998 at the Urology & Nephrology Institute of Clinical Centre of Serbia in Belgrade. Average recipients' age was 33.7 years (15-54 in LD group and 39.8 (19-62 in CD group. Retrospectively, we analyzed medical records of all recipients. Statistical analysis is estimated using Hi-squared test and Fischer's test of exact probability. RESULTS Major vascular complications including vascular anastomosis thrombosis, internal iliac artery stenosis, internal iliac artery rupture obliterant vasculitis and external iliac vein rupture were analyzed. In 25 recipients (5.4% some of major vascular complications were detected. Among these cases, 22 of them were from CD group vs. three from LD group. Relative rate of these complications was higher in CD group vs. LD group (p<0.0001. Among these complications dominant one was vascular anastomosis thrombosis which occurred in 18 recipients (17 from CD vs. one from LD. Of these recipients 16 from CD lost the graft, while the rest of two (one from each group had lethal outcome. DISCUSSION Thrombosis of renal allograft vascular anastomosis site is the most severe complication following renal transplantation. In the literature, renal allograft thrombosis is reported with different incidence rates, from 0.5-4% [14, 15, 16]. Data from the

Results from the Australasian Vascular Surgical Audit: the inaugural year.

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Beiles, C Barry; Bourke, Bernie; Thomson, Ian

2012-03-01

The Australian and New Zealand Society for Vascular Surgery has incorporated a constitutional change to administer a self-funded compulsory vascular surgery audit since January 2010. This is a bi-national quality assurance activity that captures all procedures performed in both countries. Data is collected at two points in the clinical admission; at operation and at discharge and data entry is via the Internet. Security is stringent and confidentiality is guaranteed by Commonwealth privilege. Data privacy is maximized by encryption. The application is flexible and administered by a dedicated administrator with a help-desk facility. Reports are available to provide real-time feedback of user performance compared with the peer group data in key categories of arterial surgery. A structured hierarchy for data management has been established to assess four main categories of performance: mortality after aortic surgery, stroke and death after carotid surgery, patency and limb salvage after infrainguinal bypass and patency after arteriovenous access for haemodialysis. Data is analysed using risk-adjustment techniques and an algorithm for management of underperformance has been followed. Data validation has been performed. The outcomes in all categories have been of a high standard and correction of erroneous data in a single statistical outlier has negated underperformance. The audit has captured only 65% of the estimated procedures in Australia in the first year, but data quality is good. The feasibility of a complete compulsory bi-national audit has now been established and will be the benchmark for other craft groups in the current environment of accountability. © 2012 The Authors. ANZ Journal of Surgery © 2012 Royal Australasian College of Surgeons.

Role of calcium-activated potassium channels with small conductance in bradykinin-induced vasodilation of porcine retinal arterioles

DEFF Research Database (Denmark)

Dalsgaard, Thomas; Kroigaard, Christel; Bek, Toke

2009-01-01

PURPOSE: Endothelial dysfunction and impaired vasodilation may be involved in the pathogenesis of retinal vascular diseases. In the present study, the mechanisms underlying bradykinin vasodilation were examined and whether calcium-activated potassium channels of small (SK(Ca)) and intermediate (IK...

Improved vascularization of planar membrane diffusion devices following continuous infusion of vascular endothelial growth factor.

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Trivedi, N; Steil, G M; Colton, C K; Bonner-Weir, S; Weir, G C

2000-01-01

Improving blood vessel formation around an immunobarrier device should improve the survival of the encapsulated tissue. In the present study we investigated the formation of new blood vessels around a planar membrane diffusion device (the Baxter Theracyte System) undergoing a continuous infusion of vascular endothelial growth factor through the membranes and into the surrounding tissue. Each device (20 microl) had both an inner immunoisolation membrane and an outer vascularizing membrane. Human recombinant vascular endothelial growth factor-165 was infused at 100 ng/day (low dose: n = 6) and 500 ng/day (high dose: n = 7) for 10 days into devices implanted s.c. in Sprague-Dawley rats; noninfused devices transplanted for an identical period were used as controls (n = 5). Two days following the termination of VEGF infusion, devices were loaded with 20 microl of Lispro insulin (1 U/kg) and the kinetics of insulin release from the lumen of the device was assessed. Devices were then explanted and the number of blood vessels (capillary and noncapillary) was quantified using morphometry. High-dose vascular endothelial growth factor infusion resulted in two- to threefold more blood vessels around the device than that obtained with the noninfused devices and devices infused with low-dose vascular endothelial growth factor. This increase in the number of blood vessels was accompanied by a modest increase in insulin diffusion from the device in the high-dose vascular endothelial growth factor infusion group. We conclude that vascular endothelial growth factor can be used to improve blood vessel formation adjacent to planar membrane diffusion devices.

Vascular injuries of the upper extremity Lesões vasculares de membros superiores

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Raafat Shalabi

2006-12-01

Full Text Available OBJECTIVE: This study analyzes the causes of injuries, presentations, surgical approaches, outcome and complications of vascular trauma of the upper limbs, in spite of limited hospital resources. METHODS: A 5-year retrospective analysis. From 01/01/2001 to 31/12/2005, 165 patients were operated for vascular injuries at King Fahd Hospital, Medina, Saudi Arabia. Of all peripheral vascular trauma patients (115, upper limb trauma was present in 58. Diagnosis was made by physical examination and hand-held Doppler alone or in combination with Doppler scan/angiography. Primary vascular repair was performed whenever possible; otherwise, the interposition vein graft was used. Fasciotomy was considered when required. Patients with unsalvageable lower extremity injury requiring primary amputation were excluded from the study. RESULTS: Fifty patients were male (86% and eight were female (14%, aged between 2.5-55 years (mean 23 years. Mean duration of presentation was 8 h after the injury. The most common etiological factor was road traffic accidents, accounting for 50.5% in the blunt trauma group and 33% among all penetrating and stab wound injuries. Incidence of concomitant orthopedic injuries was very high in our study (51%. The brachial artery was the most affected (51%. Interposition vein grafts were used in 53% of the cases. Limb salvage rate was 100%. CONCLUSION: Patients who suffer vascular injuries of the upper extremities should be transferred to vascular surgery centers as soon as possible. Decisive management of peripheral vascular trauma will maximize patient survival and limb salvage. Priorities must be established in the management of associated injuries, and delay must be avoided when ischemic changes are present.OBJETIVO: Este estudo analisa as causas de lesões, apresentação, abordagens cirúrgicas, desfechos e complicações do trauma vascular de membros superiores, apesar de recursos hospitalares limitados. MÉTODOS: An

Pediatric vascular access

International Nuclear Information System (INIS)

Donaldson, James S.

2006-01-01

Pediatric interventional radiologists are ideally suited to provide vascular access services to children because of inherent safety advantages and higher success from using image-guided techniques. The performance of vascular access procedures has become routine at many adult interventional radiology practices, but this service is not as widely developed at pediatric institutions. Although interventional radiologists at some children's hospitals offer full-service vascular access, there is little or none at others. Developing and maintaining a pediatric vascular access service is a challenge. Interventionalists skilled in performing such procedures are limited at pediatric institutions, and institutional support from clerical staff, nursing staff, and technologists might not be sufficiently available to fulfill the needs of such a service. There must also be a strong commitment by all members of the team to support such a demanding service. There is a slippery slope of expected services that becomes steeper and steeper as the vascular access service grows. This review is intended primarily as general education for pediatric radiologists learning vascular access techniques. Additionally, the pediatric or adult interventional radiologist seeking to expand services might find helpful tips. The article also provides education for the diagnostic radiologist who routinely interprets radiographs containing vascular access devices. (orig.)

Effects of ouabain on vascular reactivity

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Vassallo D.V.

1997-04-01

Full Text Available Ouabain is an endogenous substance occurring in the plasma in the nanomolar range, that has been proposed to increase vascular resistance and induce hypertension. This substance acts on the a-subunit of Na+,K+-ATPase inhibiting the Na+-pump activity. In the vascular smooth muscle this effect leads to intracellular Na+ accumulation that reduces the activity of the Na+/Ca2+ exchanger and to an increased vascular tone. It was also suggested that circulating ouabain, even in the nanomolar range, sensitizes the vascular smooth muscle to vasopressor substances. We tested the latter hypothesis by studying the effects of ouabain in the micromolar and nanomolar range on phenylephrine (PE-evoked pressor responses. The experiments were performed in normotensive and hypertensive rats in vivo, under anesthesia, and in perfused rat tail vascular beds. The results showed that ouabain pretreatment increased the vasopressor responses to PE in vitro and in vivo. This sensitization after ouabain treatment was also observed in hypertensive animals which presented an enhanced vasopressor response to PE in comparison to normotensive animals. It is suggested that ouabain at nanomolar concentrations can sensitize vascular smooth muscle to vasopressor stimuli possibly contributing to increased tone in hypertension

Macrophage migration inhibitory factor induces vascular leakage via autophagy

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Hong-Ru Chen

2015-01-01

Full Text Available Vascular leakage is an important feature of acute inflammatory shock, which currently has no effective treatment. Macrophage migration inhibitory factor (MIF is a pro-inflammatory cytokine that can induce vascular leakage and plays an important role in the pathogenesis of shock. However, the mechanism of MIF-induced vascular leakage is still unclear. In this study, using recombinant MIF (rMIF, we demonstrated that MIF induced disorganization and degradation of junction proteins and increased the permeability of human endothelial cells in vitro. Western blotting analysis showed that rMIF treatment induced LC3 conversion and p62 degradation. Inhibition of autophagy with a PI3K inhibitor (3-MA, a ROS scavenger (NAC or autophagosomal-lysosomal fusion inhibitors (bafilomycin A1 and chloroquine rescued rMIF-induced vascular leakage, suggesting that autophagy mediates MIF-induced vascular leakage. The potential involvement of other signaling pathways was also studied using different inhibitors, and the results suggested that MIF-induced vascular leakage may occur through the ERK pathway. In conclusion, we showed that MIF triggered autophagic degradation of endothelial cells, resulting in vascular leakage. Inhibition of MIF-induced autophagy may provide therapeutic targets against vascular leakage in inflammatory shock.

Image Quality in Vascular Radiology

International Nuclear Information System (INIS)

Vanhavere, F.; Struelens, L.

2005-01-01

In vascular radiology, the radiologists use the radiological image to diagnose or treat a specific vascular structure. From literature, we know that related doses are high and that large dose variability exists between different hospitals. The application of the optimization principle is therefore necessary and is obliged by the new legislation. So far, very little fieldwork has been performed and no practical instructions are available to do the necessary work. It's indisputable that obtaining quantitative data is of great interest for optimization purposes. In order to gain insight into these doses and the possible measures for dose reduction, we performed a comparative study in 7 hospitals. Patient doses will be measured and calculated for specific procedures in vascular radiology and evaluated against their most influencing parameters. In view of optimization purposes, a protocol for dose audit will be set-up. From the results and conclusions in this study, experimentally based guidelines will be proposed, in order to improve clinical practice in vascular radiology

Cerebrovascular endothelin-1 hyper-reactivity is associated with transient receptor potential canonical channels 1 and 6 activation and delayed cerebral hypoperfusion after forebrain ischaemia in rats

DEFF Research Database (Denmark)

Johansson, S E; Andersen, X E D R; Hansen, R H

2015-01-01

. METHODS: Experimental forebrain ischaemia was induced in Wistar male rats by a two-vessel occlusion model, and the cerebral blood flow was measured by magnetic resonance imaging two days after reperfusion. In vitro vasoreactivity studies, immunofluorescence and quantitative PCR were performed on cerebral...... in the vascular smooth muscle cells was enhanced and correlated with decreased cerebral blood flow two days after forebrain ischaemia. Furthermore, under conditions when voltage-dependent calcium channels were inhibited, endothelin-1-induced cerebrovascular contraction was enhanced and this enhancement...... was presumably mediated by Ca(2+) influx via upregulated transient receptor potential canonical channels 1 and 6. CONCLUSIONS: Our data demonstrates that endothelin-1-mediated influx of extracellular Ca(2+) activates transient receptor potential canonical channels 1 and 6 in cerebral vascular smooth muscle cells...

In vivo endothelization of tubular vascular grafts through in situ recruitment of endothelial and endothelial progenitor cells by RGD-fused mussel adhesive proteins

International Nuclear Information System (INIS)

Kang, Tae-Yun; Lee, Jung Ho; Kang, Jo-A; Rhie, Jong-Won; Kim, Bum Jin; Cha, Hyung Joon; Hong, Jung Min; Kim, Byoung Soo; Cho, Dong-Woo

2015-01-01

The use of tissue mimics in vivo, including patterned vascular networks, is expected to facilitate the regeneration of functional tissues and organs with large volumes. Maintaining patency of channels in contact with blood is an important issue in the development of a functional vascular network. Endothelium is the only known completely non-thrombogenic material; however, results from treatments to induce endothelialization are inconclusive. The present study was designed to evaluate the clinical applicability of in situ recruitment of endothelial cells/endothelial progenitor cells (EC/EPC) and pre-endothelization using a recombinant mussel adhesive protein fused with arginine–glycine–aspartic acid peptide (MAP-RGD) coating in a model of vascular graft implantation. Microporous polycaprolactone (PCL) scaffolds were fabricated with salt leaching methods and their surfaces were modified with collagen and MAP-RGD. We then evaluated their anti-thrombogenicity with an in vitro hemocompatibility assessment and a 4-week implantation in the rabbit carotid artery. We observed that MAP-RGD coating reduced the possibility of early in vivo graft failure and enhanced re-endothelization by in situ recruitment of EC/EPC (patency rate: 2/3), while endothelization prior to implantation aggravated the formation of thrombosis and/or IH (patency rate: 0/3). The results demonstrated that in situ recruitment of EC/EPC by MAP-RGD could be a promising strategy for vascular applications. In addition, it rules out several issues associated with pre-endothelization, such as cell source, purity, functional modulation and contamination. Further evaluation of long term performance and angiogenesis from the luminal surface may lead to the clinical use of MAP-RGD for tubular vascular grafts and regeneration of large-volume tissues with functional vascular networks. (paper)

Lipidomics in vascular health: current perspectives.

Science.gov (United States)

Kolovou, Genovefa; Kolovou, Vana; Mavrogeni, Sophie

2015-01-01

Identifying the mechanisms that convert a healthy vascular wall to an atherosclerotic wall is of major importance since the consequences may lead to a shortened lifespan. Classical risk factors (age, smoking, obesity, diabetes mellitus, hypertension, and dyslipidemia) may result in the progression of atherosclerotic lesions by processes including inflammation and lipid accumulation. Thus, the evaluation of blood lipids and the full lipid complement produced by cells, organisms, or tissues (lipidomics) is an issue of importance. In this review, we shall describe the recent progress in vascular health research using lipidomic advances. We will begin with an overview of vascular wall biology and lipids, followed by a short analysis of lipidomics. Finally, we shall focus on the clinical implications of lipidomics and studies that have examined lipidomic approaches and vascular health.

A Novel Strategy to Engineer Pre-Vascularized Full-Length Dental Pulp-like Tissue Constructs.

Science.gov (United States)

Athirasala, Avathamsa; Lins, Fernanda; Tahayeri, Anthony; Hinds, Monica; Smith, Anthony J; Sedgley, Christine; Ferracane, Jack; Bertassoni, Luiz E

2017-06-12

The requirement for immediate vascularization of engineered dental pulp poses a major hurdle towards successful implementation of pulp regeneration as an effective therapeutic strategy for root canal therapy, especially in adult teeth. Here, we demonstrate a novel strategy to engineer pre-vascularized, cell-laden hydrogel pulp-like tissue constructs in full-length root canals for dental pulp regeneration. We utilized gelatin methacryloyl (GelMA) hydrogels with tunable physical and mechanical properties to determine the microenvironmental conditions (microstructure, degradation, swelling and elastic modulus) that enhanced viability, spreading and proliferation of encapsulated odontoblast-like cells (OD21), and the formation of endothelial monolayers by endothelial colony forming cells (ECFCs). GelMA hydrogels with higher polymer concentration (15% w/v) and stiffness enhanced OD21 cell viability, spreading and proliferation, as well as endothelial cell spreading and monolayer formation. We then fabricated pre-vascularized, full-length, dental pulp-like tissue constructs by dispensing OD21 cell-laden GelMA hydrogel prepolymer in root canals of extracted teeth and fabricating 500 µm channels throughout the root canals. ECFCs seeded into the microchannels successfully formed monolayers and underwent angiogenic sprouting within 7 days in culture. In summary, the proposed approach is a simple and effective strategy for engineering of pre-vascularized dental pulp constructs offering potentially beneficial translational outcomes.

Channel Bow in Boiling Water Reactors - Hot Cell Examination Results and Correlation to Measured Bow

International Nuclear Information System (INIS)

Mahmood, S.T.; Lin, Y.P.; Dubecky, M.A.; Edsinger, K.; Mader, E.V.

2007-01-01

An increase in frequency of fuel channel-control blade interference has been observed in Boiling Water Reactors (BWR) in recent years. Many of the channels leading to interference were found to bow towards the control blade in a manner that was inconsistent with the expected bow due to other effects. The pattern of bow appeared to indicate a new channel bow mechanism that differed from the predominant bow mechanism caused by differential growth due to fast-fluence gradients. In order to investigate this new type of channel bow, coupons from several channels with varying degrees of bow were returned to the GE Vallecitos Nuclear Center (VNC) for Post-Irradiation Examination (PIE). This paper describes the characteristics of channel corrosion and hydrogen pickup observed, and relates the observations to the channel exposure level, control history, and measured channel bow. The channels selected for PIE had exposures in the range of 36-48 GWd/MTU and covered a wide range of measured bow. The coupons were obtained at 4 elevations from opposing channel sides adjacent and away from the control blade. The PIE performed on these coupons included visual examination, metallography, and hydrogen concentration measurements. A new mechanism of control-blade shadow corrosion-induced channel bow was found to correlate with differences in the extent of corrosion and corresponding differences in the hydrogen concentration between opposite sides of the channels. The increased corrosion on the control blade sides was found to be dependent on the level of control early in the life of the channel. The contributions of other potential factors leading to increased channel bow and channel-control blade interference are also discussed in this paper. (authors)

Experimental Results and Issues on Equalization for Nonlinear Memory Channel: Pre-Cursor Enhanced Ram-DFE Canceler

Science.gov (United States)

Yuan, Lu; LeBlanc, James

1998-01-01

This thesis investigates the effects of the High Power Amplifier (HPA) and the filters over a satellite or telemetry channel. The Volterra series expression is presented for the nonlinear channel with memory, and the algorithm is based on the finite-state machine model. A RAM-based algorithm operating on the receiver side, Pre-cursor Enhanced RAM-FSE Canceler (PERC) is developed. A high order modulation scheme , 16-QAM is used for simulation, the results show that PERC provides an efficient and reliable method to transmit data on the bandlimited nonlinear channel. The contribution of PERC algorithm is that it includes both pre-cursors and post-cursors as the RAM address lines, and suggests a new way to make decision on the pre-addresses. Compared with the RAM-DFE structure that only includes post- addresses, the BER versus Eb/NO performance of PERC is substantially enhanced. Experiments are performed for PERC algorithms with different parameters on AWGN channels, and the results are compared and analyzed. The investigation of this thesis includes software simulation and hardware verification. Hardware is setup to collect actual TWT data. Simulation on both the software-generated data and the real-world data are performed. Practical limitations are considered for the hardware collected data. Simulation results verified the reliability of the PERC algorithm. This work was conducted at NMSU in the Center for Space Telemetering and Telecommunications Systems in the Klipsch School of Electrical and Computer Engineering Department.

Vascular Access in Children

International Nuclear Information System (INIS)

Krishnamurthy, Ganesh; Keller, Marc S.

2011-01-01

Establishment of stable vascular access is one of the essential and most challenging procedures in a pediatric hospital. Many clinical specialties provide vascular service in a pediatric hospital. At the top of the “expert procedural pyramid” is the pediatric interventional radiologist, who is best suited and trained to deliver this service. Growing awareness regarding the safety and high success rate of vascular access using image guidance has led to increased demand from clinicians to provide around-the-clock vascular access service by pediatric interventional radiologists. Hence, the success of a vascular access program, with the pediatric interventional radiologist as the key provider, is challenging, and a coordinated multidisciplinary team effort is essential for success. However, there are few dedicated pediatric interventional radiologists across the globe, and also only a couple of training programs exist for pediatric interventions. This article gives an overview of the technical aspects of pediatric vascular access and provides useful tips for obtaining vascular access in children safely and successfully using image guidance.

Comparison of the effects of the K(+)-channel openers cromakalim and minoxidil sulphate on vascular smooth muscle.

Science.gov (United States)

Wickenden, A. D.; Grimwood, S.; Grant, T. L.; Todd, M. H.

1991-01-01

1 The actions of the potassium channel openers, cromakalim and minoxidil sulphate, were compared in a range of isolated blood vessel preparations. 2 Cromakalim and minoxidil sulphate inhibited spontaneous mechanical activity of the guinea-pig portal vein and relaxed the noradrenaline precontracted rat aorta with similar potency. In contrast, minoxidil sulphate was less potent than cromakalim in inhibiting spontaneous activity in the rat portal vein and was essentially inactive in the noradrenaline precontracted rat mesenteric artery and rabbit aorta. 3 Minoxidil sulphate did not antagonize the effects of cromakalim in the rabbit aorta indicating it was not acting as a partial 'agonist'. 4 Charybdotoxin, noxiustoxin and rubidium failed to discriminate between cromakalim and minoxidil sulphate indicating that the apparently selective effects of minoxidil sulphate were not mediated by either Ca(2+)-activated potassium channels, delayed rectifiers or rubidium impermeable potassium channels. 5 Glibenclamide antagonized the effects of cromakalim in an apparently competitive manner whereas the effects of minoxidil sulphate were antagonized in a non-competitive manner. The involvement of subtypes of ATP-sensitive potassium channels is discussed. PMID:1878752

Oscillation of Angiogenesis and Vascular Dropout in Progressive Human Vascular Disease. [Vascular Pattern as Useful Read-Out of Complex Molecular Signaling

Science.gov (United States)

Parsons-Wingerter, Patricia

2010-01-01

When analyzed by VESsel GENeration Analysis (VESGEN) software, vascular patterns provide useful integrative read-outs of complex, interacting molecular signaling pathways. Using VESGEN, we recently discovered and published our innovative, surprising findings that angiogenesis oscillated with vascular dropout throughout progression of diabetic retinopathy, a blinding vascular disease. Our findings provide a potential paradigm shift in the current prevailing view on progression and treatment of this disease, and a new early-stage window of regenerative therapeutic opportunities. The findings also suggest that angiogenesis may oscillate with vascular disease in a homeostatic-like manner during early stages of other inflammatory progressive diseases such as cancer and coronary vascular disease.

Longitudinal visualization of vascular occlusion, reperfusion, and remodeling in a zebrafish model of retinal vascular leakage using OCT angiography

Science.gov (United States)

Spitz, Kathleen; Bozic, Ivan; Desai, Vineet; Rao, Gopikrishna M.; Pollock, Lana M.; Anand-Apte, Bela; Tao, Yuankai K.

2017-02-01

Diabetic retinopathy (DR) and age-related macular degeneration (AMD) are two of the leading causes of blindness and visual impairment in the world. Neovascularization results in severe vision loss in DR and AMD and, thus, there is an unmet need to identify mechanisms of pathogenesis and novel anti-angiogenic therapies. Zebrafish is a leading model organism for studying human disease pathogenesis, and the highly conserved drug activity between zebrafish and humans and their ability to readily absorb small molecules dissolved in water has benefited pharmaceutical discovery. Here, we use optical coherence tomography (OCT) and OCT angiography (OCT-A) to perform noninvasive, in vivo retinal imaging in a zebrafish model of vascular leakage. Zebrafish were treated with diethylaminobenzaldehyde (DEAB) to induce vascular leakage and imaged with OCT and OCT-A at six time points over two weeks: baseline one day before treatment and one, three, six, eight, and ten days post treatment. Longitudinal functional imaging showed significant vascular response immediately after DEAB treatment. Observed vascular changes included partial or complete vascular occlusion immediately after treatment and reperfusion during a two-week period. Increased vascular tortuosity several days post treatment indicated remodeling, and bifurcations and collateral vessel formation were also observed. In addition, significant treatment response variabilities were observed in the contralateral eye of the same animal. Anatomical and functional normalization was observed in most animals by ten days post treatment. These preliminary results motivate potential applications of OCT-A as a tool for studying pathogenesis and therapeutic screening in zebrafish models of retinal vascular disease.

[Vascular Calcification - Pathological Mechanism and Clinical Application - . Role of vascular smooth muscle cells in vascular calcification].

Science.gov (United States)

Kurabayashi, Masahiko

2015-05-01

Vascular calcification is commonly seen with aging, chronic kidney disese (CKD), diabetes, and atherosclerosis, and is closely associated with cardiovascular morbidity and mortality. Vascular calcification has long been regarded as the final stage of degeneration and necrosis of arterial wall and a passive, unregulated process. However, it is now known to be an active and tightly regulated process involved with phenotypic transition of vascular smooth muscle cells (VSMC) that resembles bone mineralization. Briefly, calcium deposits of atherosclerotic plaque consist of hydroxyapatite and may appear identical to fully formed lamellar bone. By using a genetic fate mapping strategy, VSMC of the vascular media give rise to the majority of the osteochondrogenic precursor- and chondrocyte-like cells observed in the calcified arterial media of MGP (- / -) mice. Osteogenic differentiation of VSMC is characterized by the expression of bone-related molecules including bone morphogenetic protein (BMP) -2, Msx2 and osteopontin, which are produced by osteoblasts and chondrocytes. Our recent findings are that (i) Runx2 and Notch1 induce osteogenic differentiation, and (ii) advanced glycation end-product (AGE) /receptor for AGE (RAGE) and palmitic acid promote osteogenic differentiation of VSMC. To understand of the molecular mechanisms of vascular calcification is now under intensive research area.

Vascular Gene Expression: A Hypothesis

Directory of Open Access Journals (Sweden)

Angélica Concepción eMartínez-Navarro

2013-07-01

Full Text Available The phloem is the conduit through which photoassimilates are distributed from autotrophic to heterotrophic tissues and is involved in the distribution of signaling molecules that coordinate plant growth and responses to the environment. Phloem function depends on the coordinate expression of a large array of genes. We have previously identified conserved motifs in upstream regions of the Arabidopsis genes, encoding the homologs of pumpkin phloem sap mRNAs, displaying expression in vascular tissues. This tissue-specific expression in Arabidopsis is predicted by the overrepresentation of GA/CT-rich motifs in gene promoters. In this work we have searched for common motifs in upstream regions of the homologous genes from plants considered to possess a primitive vascular tissue (a lycophyte, as well as from others that lack a true vascular tissue (a bryophyte, and finally from chlorophytes. Both lycophyte and bryophyte display motifs similar to those found in Arabidopsis with a significantly low E-value, while the chlorophytes showed either a different conserved motif or no conserved motif at all. These results suggest that these same genes are expressed coordinately in non- vascular plants; this coordinate expression may have been one of the prerequisites for the development of conducting tissues in plants. We have also analyzed the phylogeny of conserved proteins that may be involved in phloem function and development. The presence of CmPP16, APL, FT and YDA in chlorophytes suggests the recruitment of ancient regulatory networks for the development of the vascular tissue during evolution while OPS is a novel protein specific to vascular plants.

Inward rectifier potassium (Kir2.1) channels as end‐stage boosters of endothelium‐dependent vasodilators

Science.gov (United States)

Dalsgaard, Thomas; Bonev, Adrian D.; Nelson, Mark T.

2016-01-01

Key points Increase in endothelial cell (EC) calcium activates calcium‐sensitive intermediate and small conductance potassium (IK and SK) channels, thereby causing hyperpolarization and endothelium‐dependent vasodilatation.Endothelial cells express inward rectifier potassium (Kir) channels, but their role in endothelium‐dependent vasodilatation is not clear.In the mesenteric arteries, only ECs, but not smooth muscle cells, displayed Kir currents that were predominantly mediated by the Kir2.1 isoform.Endothelium‐dependent vasodilatations in response to muscarinic receptor, TRPV4 (transient receptor potential vanilloid 4) channel and IK/SK channel agonists were highly attenuated by Kir channel inhibitors and by Kir2.1 channel knockdown.These results point to EC Kir channels as amplifiers of vasodilatation in response to increases in EC calcium and IK/SK channel activation and suggest that EC Kir channels could be targeted to treat endothelial dysfunction, which is a hallmark of vascular disorders. Abstract Endothelium‐dependent vasodilators, such as acetylcholine, increase intracellular Ca2+ through activation of transient receptor potential vanilloid 4 (TRPV4) channels in the plasma membrane and inositol trisphosphate receptors in the endoplasmic reticulum, leading to stimulation of Ca2+‐sensitive intermediate and small conductance K+ (IK and SK, respectively) channels. Although strong inward rectifier K+ (Kir) channels have been reported in the native endothelial cells (ECs) their role in EC‐dependent vasodilatation is not clear. Here, we test the idea that Kir channels boost the EC‐dependent vasodilatation of resistance‐sized arteries. We show that ECs, but not smooth muscle cells, of small mesenteric arteries have Kir currents, which are substantially reduced in EC‐specific Kir2.1 knockdown (EC‐Kir2.1 −/−) mice. Elevation of extracellular K+ to 14 mm caused vasodilatation of pressurized arteries, which was prevented by endothelial

Inward rectifier potassium (Kir2.1) channels as end-stage boosters of endothelium-dependent vasodilators.

Science.gov (United States)

Sonkusare, Swapnil K; Dalsgaard, Thomas; Bonev, Adrian D; Nelson, Mark T

2016-06-15

Increase in endothelial cell (EC) calcium activates calcium-sensitive intermediate and small conductance potassium (IK and SK) channels, thereby causing hyperpolarization and endothelium-dependent vasodilatation. Endothelial cells express inward rectifier potassium (Kir) channels, but their role in endothelium-dependent vasodilatation is not clear. In the mesenteric arteries, only ECs, but not smooth muscle cells, displayed Kir currents that were predominantly mediated by the Kir2.1 isoform. Endothelium-dependent vasodilatations in response to muscarinic receptor, TRPV4 (transient receptor potential vanilloid 4) channel and IK/SK channel agonists were highly attenuated by Kir channel inhibitors and by Kir2.1 channel knockdown. These results point to EC Kir channels as amplifiers of vasodilatation in response to increases in EC calcium and IK/SK channel activation and suggest that EC Kir channels could be targeted to treat endothelial dysfunction, which is a hallmark of vascular disorders. Endothelium-dependent vasodilators, such as acetylcholine, increase intracellular Ca(2+) through activation of transient receptor potential vanilloid 4 (TRPV4) channels in the plasma membrane and inositol trisphosphate receptors in the endoplasmic reticulum, leading to stimulation of Ca(2+) -sensitive intermediate and small conductance K(+) (IK and SK, respectively) channels. Although strong inward rectifier K(+) (Kir) channels have been reported in the native endothelial cells (ECs) their role in EC-dependent vasodilatation is not clear. Here, we test the idea that Kir channels boost the EC-dependent vasodilatation of resistance-sized arteries. We show that ECs, but not smooth muscle cells, of small mesenteric arteries have Kir currents, which are substantially reduced in EC-specific Kir2.1 knockdown (EC-Kir2.1(-/-) ) mice. Elevation of extracellular K(+) to 14 mm caused vasodilatation of pressurized arteries, which was prevented by endothelial denudation and Kir channel

Novel asymptotic results on the high-order statistics of the channel capacity over generalized fading channels

KAUST Repository

Yilmaz, Ferkan; Alouini, Mohamed-Slim

2012-01-01

The exact analysis of the higher-order statistics of the channel capacity (i.e., higher-order ergodic capacity) often leads to complicated expressions involving advanced special functions. In this paper, we provide a generic framework

Uterine Vascular Lesions

Science.gov (United States)

Vijayakumar, Abhishek; Srinivas, Amruthashree; Chandrashekar, Babitha Moogali; Vijayakumar, Avinash

2013-01-01

Vascular lesions of the uterus are rare; most reported in the literature are arteriovenous malformations (AVMs). Uterine AVMs can be congenital or acquired. In recent years, there has been an increasing number of reports of acquired vascular lesions of the uterus following pregnancy, abortion, cesarean delivery, and curettage. It can be seen from these reports that there is confusion concerning the terminology of uterine vascular lesions. There is also a lack of diagnostic criteria and management guidelines, which has led to an increased number of unnecessary invasive procedures (eg, angiography, uterine artery embolization, hysterectomy for abnormal vaginal bleeding). This article familiarizes readers with various vascular lesions of the uterus and their management. PMID:24340126

New Results on Single-Channel Speech Separation Using Sinusoidal Modeling

DEFF Research Database (Denmark)

Mowlaee, Pejman; Christensen, Mads Græsbøll; Jensen, Søren Holdt

2011-01-01

We present new results on single-channel speech separation and suggest a new separation approach to improve the speech quality of separated signals from an observed mix- ture. The key idea is to derive a mixture estimator based on sinusoidal parameters. The proposed estimator is aimed at finding...... mixture estimator used in binary masks and the Wiener filtering approach, it is observed that the proposed method achieves an acceptable perceptual speech quality with less cross- talk at different signal-to-signal ratios. Moreover, the method is independent of pitch estimates and reduces the computational...... complexity of the separation by replacing the short-time Fourier transform (STFT) feature vectors of high dimensionality with sinusoidal feature vectors. We report separation results for the proposed method and compare them with respect to other benchmark methods. The improvements made by applying...

Impaired vascular function after exposure to diesel exhaust generated at urban transient running conditions

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Westerholm Roger

2010-07-01

Full Text Available Abstract Background Traffic emissions including diesel engine exhaust are associated with increased respiratory and cardiovascular morbidity and mortality. Controlled human exposure studies have demonstrated impaired vascular function after inhalation of exhaust generated by a diesel engine under idling conditions. Objectives To assess the vascular and fibrinolytic effects of exposure to diesel exhaust generated during urban-cycle running conditions that mimic ambient 'real-world' exposures. Methods In a randomised double-blind crossover study, eighteen healthy male volunteers were exposed to diesel exhaust (approximately 250 μg/m3 or filtered air for one hour during intermittent exercise. Diesel exhaust was generated during the urban part of the standardized European Transient Cycle. Six hours post-exposure, vascular vasomotor and fibrinolytic function was assessed during venous occlusion plethysmography with intra-arterial agonist infusions. Measurements and Main Results Forearm blood flow increased in a dose-dependent manner with both endothelial-dependent (acetylcholine and bradykinin and endothelial-independent (sodium nitroprusside and verapamil vasodilators. Diesel exhaust exposure attenuated the vasodilatation to acetylcholine (P Conclusion Exposure to diesel exhaust generated under transient running conditions, as a relevant model of urban air pollution, impairs vasomotor function and endogenous fibrinolysis in a similar way as exposure to diesel exhaust generated at idling. This indicates that adverse vascular effects of diesel exhaust inhalation occur over different running conditions with varying exhaust composition and concentrations as well as physicochemical particle properties. Importantly, exposure to diesel exhaust under ETC conditions was also associated with a novel finding of impaired of calcium channel-dependent vasomotor function. This implies that certain cardiovascular endpoints seem to be related to general diesel

Vascular dementia | Connor | African Journal of Psychiatry

African Journals Online (AJOL)

Vascular dementia (VaD) is a common but heterogeneous condition in which there is a clear temporal relationship between the dementia and vascular disease. It may result from multiple large or small vessel strokes or a single strategic stroke. Subcortical ischaemic VaD includes multiple lacunes and subcortical ...

Estrogen, vascular estrogen receptor and hormone therapy in postmenopausal vascular disease.

Science.gov (United States)

Khalil, Raouf A

2013-12-15

Cardiovascular disease (CVD) is less common in premenopausal women than men of the same age or postmenopausal women, suggesting vascular benefits of estrogen. Estrogen activates estrogen receptors ERα, ERβ and GPR30 in endothelium and vascular smooth muscle (VSM), which trigger downstream signaling pathways and lead to genomic and non-genomic vascular effects such as vasodilation, decreased VSM contraction and growth and reduced vascular remodeling. However, randomized clinical trials (RCTs), such as the Women's Health Initiative (WHI) and Heart and Estrogen/progestin Replacement Study (HERS), have shown little vascular benefits and even adverse events with menopausal hormone therapy (MHT), likely due to factors related to the MHT used, ER profile, and RCT design. Some MHT forms, dose, combinations or route of administration may have inadequate vascular effects. Age-related changes in ER amount, distribution, integrity and post-ER signaling could alter the vascular response to MHT. The subject's age, preexisting CVD, and hormone environment could also reduce the effects of MHT. Further evaluation of natural and synthetic estrogens, phytoestrogens, and selective estrogen-receptor modulators (SERMs), and the design of appropriate MHT combinations, dose, route and 'timing' could improve the effectiveness of conventional MHT and provide alternative therapies in the peri-menopausal period. Targeting ER using specific ER agonists, localized MHT delivery, and activation of specific post-ER signaling pathways could counter age-related changes in ER. Examination of the hormone environment and conditions associated with hormone imbalance such as polycystic ovary syndrome may reveal the causes of abnormal hormone-receptor interactions. Consideration of these factors in new RCTs such as the Kronos Early Estrogen Prevention Study (KEEPS) could enhance the vascular benefits of estrogen in postmenopausal CVD. Copyright © 2013 Elsevier Inc. All rights reserved.

Prediction of Thorough QT study results using action potential simulations based on ion channel screens.

Science.gov (United States)

Mirams, Gary R; Davies, Mark R; Brough, Stephen J; Bridgland-Taylor, Matthew H; Cui, Yi; Gavaghan, David J; Abi-Gerges, Najah

2014-01-01

Detection of drug-induced pro-arrhythmic risk is a primary concern for pharmaceutical companies and regulators. Increased risk is linked to prolongation of the QT interval on the body surface ECG. Recent studies have shown that multiple ion channel interactions can be required to predict changes in ventricular repolarisation and therefore QT intervals. In this study we attempt to predict the result of the human clinical Thorough QT (TQT) study, using multiple ion channel screening which is available early in drug development. Ion current reduction was measured, in the presence of marketed drugs which have had a TQT study, for channels encoded by hERG, CaV1.2, NaV1.5, KCNQ1/MinK, and Kv4.3/KChIP2.2. The screen was performed on two platforms - IonWorks Quattro (all 5 channels, 34 compounds), and IonWorks Barracuda (hERG & CaV1.2, 26 compounds). Concentration-effect curves were fitted to the resulting data, and used to calculate a percentage reduction in each current at a given concentration. Action potential simulations were then performed using the ten Tusscher and Panfilov (2006), Grandi et al. (2010) and O'Hara et al. (2011) human ventricular action potential models, pacing at 1Hz and running to steady state, for a range of concentrations. We compared simulated action potential duration predictions with the QT prolongation observed in the TQT studies. At the estimated concentrations, simulations tended to underestimate any observed QT prolongation. When considering a wider range of concentrations, and conventional patch clamp rather than screening data for hERG, prolongation of ≥5ms was predicted with up to 79% sensitivity and 100% specificity. This study provides a proof-of-principle for the prediction of human TQT study results using data available early in drug development. We highlight a number of areas that need refinement to improve the method's predictive power, but the results suggest that such approaches will provide a useful tool in cardiac safety

Audit of the Danish national vascular database

DEFF Research Database (Denmark)

Levi-Mazloum, Niels Donald; Jensen, L P; Schroeder, T V

1996-01-01

The accuracy of data contained in the Danish vascular database was compared with the case notes. A total of 100 case notes were reviewed for 11 pertinent variables in the database. A high error rate ranging from 2 to 34% was found. Also, approximately 10% of patients had never been entered into t...... into the vascular database. Further improvement of the Danish vascular database is necessary for its use as basis for reporting results.......The accuracy of data contained in the Danish vascular database was compared with the case notes. A total of 100 case notes were reviewed for 11 pertinent variables in the database. A high error rate ranging from 2 to 34% was found. Also, approximately 10% of patients had never been entered...

The vascular surgery workforce: a survey of consultant vascular surgeons in the UK, 2014.

Science.gov (United States)

Harkin, D W; Beard, J D; Shearman, C P; Wyatt, M G

2015-04-01

The purpose of this study was to describe the demographics, training, and practice characteristics of consultant vascular surgeons across the UK to provide an assessment of current, and inform future prediction of workforce needs. A questionnaire was developed using a modified Delphi process to generate questionnaire items. The questionnaire was emailed to all consultant vascular surgeons (n = 450) in the UK who were members of the Vascular Society of Great Britain & Ireland. 352 consultant vascular surgeons from 95 hospital trusts across the UK completed the survey (78% response rate). The mean age was 50.6 years old, the majority (62%) were mid-career, but 24% were above the age of 55. Currently, 92% are men and only 8% women. 93% work full-time, with 60% working >50 hours, and 21% working >60 hours per week. The average team was 5 to 6 (range 2-10) vascular surgeons, with 23% working in a large team of ≥8. 17% still work in small teams of ≤3. Over 90% of consultant vascular surgeons perform the major index vascular surgery procedures (aneurysm repair, carotid endarterectomy, infra-inguinal bypass, amputation). While 84% perform standard endovascular abdominal aortic aneurysm repair (EVAR), <50% perform more complex endovascular aortic therapy. The majority of vascular surgeons "like their job" (85%) and are "satisfied" (69%) with their job. 34% of consultant vascular surgeons indicated they were "extremely likely" to retire within the next 10 years. This study provides the first detailed analysis of the new specialty of vascular surgery as practiced in the UK. There is a need to plan for a significant expansion in the consultant vascular surgeon workforce in the UK over the next 10 years to maintain the status quo. Copyright © 2014 European Society for Vascular Surgery. Published by Elsevier Ltd. All rights reserved.

Preliminary results on 3D channel modeling: From theory to standardization

KAUST Repository

Kammoun, Abla; Khanfir, Hajer; Altman, Zwi; Debbah, Mé roú ane; Kamoun, Mohamed Amine

2014-01-01

Three dimensional (3D) beamforming (also elevation beamforming) is now gaining interest among researchers in wireless communication. The reason can be attributed to its potential for enabling a variety of strategies such as sector or user specific elevation beamforming and cell-splitting. Since these techniques cannot be directly supported by current LTE releases, the 3GPP is now working on defining the required technical specifications. In particular, a large effort is currently being made to get accurate 3D channel models that support the elevation dimension. This step is necessary as it will evaluate the potential of 3D and full dimensional (FD) beamforming techniques to benefit from the richness of real channels. This work aims at presenting the on-going 3GPP study item 'study on 3D-channel model for elevation beamforming and FD-MIMO studies for LTE' and positioning it with respect to previous standardization works. © 2014 IEEE.

Preliminary results on 3D channel modeling: From theory to standardization

KAUST Repository

Kammoun, Abla

2014-06-01

Three dimensional (3D) beamforming (also elevation beamforming) is now gaining interest among researchers in wireless communication. The reason can be attributed to its potential for enabling a variety of strategies such as sector or user specific elevation beamforming and cell-splitting. Since these techniques cannot be directly supported by current LTE releases, the 3GPP is now working on defining the required technical specifications. In particular, a large effort is currently being made to get accurate 3D channel models that support the elevation dimension. This step is necessary as it will evaluate the potential of 3D and full dimensional (FD) beamforming techniques to benefit from the richness of real channels. This work aims at presenting the on-going 3GPP study item \\'study on 3D-channel model for elevation beamforming and FD-MIMO studies for LTE\\' and positioning it with respect to previous standardization works. © 2014 IEEE.

Jellyfish Envenomation Resulting In Vascular Insufficiency And Neurogenic Injury of Upper Limb

Directory of Open Access Journals (Sweden)

Choong CYL

2015-11-01

Full Text Available Following a week after a jellyfish sting, a young man presented with regional cyanosis and threat of distal gangrene secondary to vascular spasm in the forearm. The patient also suffered from transient paresis and numbness of the affected upper limb. Contrasted imaging revealed unopacified vessels in the distal forearm and worsening swelling warranted emergency surgical fasciotomy for impending compartment syndrome. This case highlights the occurrence of jellyfish envenomation and the need for early treatment.

Congenital vascular malformations in scintigraphic evaluation

International Nuclear Information System (INIS)

Pilecki, Stanisław; Gierach, Marcin; Gierach, Joanna; Świętaszczyk, Cyprian; Junik, Roman; Lasek, Władysław

2014-01-01

Congenital vascular malformations are tumour-like, non-neoplastic lesions caused by disorders of vascular tissue morphogenesis. They are characterised by a normal cell replacement cycle throughout all growth phases and do not undergo spontaneous involution. Here we present a scintigraphic image of familial congenital vascular malformations in two sisters. A 17-years-old young woman with a history of multiple hospitalisations for foci of vascular anomalies appearing progressively in the upper and lower right limbs, chest wall and spleen. A Parkes Weber syndrome was diagnosed based on the clinical picture. Due to the occurrence of new foci of malformations, a whole-body scintigraphic examination was performed. A 12-years-old girl reported a lump in the right lower limb present for approximately 2 years, which was clinically identified as a vascular lesion in the area of calcaneus and talus. Phleboscintigraphy visualized normal radiomarker outflow from the feet via the deep venous system, also observed in the superficial venous system once the tourniquets were released. In static and whole-body examinations vascular malformations were visualised in the area of the medial cuneiform, navicular and talus bones of the left foot, as well as in the projection of right calcaneus and above the right talocrural joint. People with undiagnosed disorders related to the presence of vascular malformations should undergo periodic follow-up to identify lesions that may be the cause of potentially serious complications and to assess the results of treatment. Presented scintigraphic methods may be used for both diagnosing and monitoring of disease progression

VEGFR tyrosine kinase inhibitor II (VRI) induced vascular insufficiency in zebrafish as a model for studying vascular toxicity and vascular preservation

International Nuclear Information System (INIS)

Li, Shang; Dang, Yuan Ye; Oi Lam Che, Ginny; Kwan, Yiu Wa; Chan, Shun Wan; Leung, George Pak Heng; Lee, Simon Ming Yuen; Hoi, Maggie Pui Man

2014-01-01

In ischemic disorders such as chronic wounds and myocardial ischemia, there is inadequate tissue perfusion due to vascular insufficiency. Besides, it has been observed that prolonged use of anti-angiogenic agents in cancer therapy produces cardiovascular toxicity caused by impaired vessel integrity and regeneration. In the present study, we used VEGFR tyrosine kinase inhibitor II (VRI) to chemically induce vascular insufficiency in zebrafish in vivo and human umbilical vein endothelial cells (HUVEC) in vitro to further study the mechanisms of vascular morphogenesis in these pathological conditions. We also explored the possibility of treating vascular insufficiency by enhancing vascular regeneration and repair with pharmacological intervention. We observed that pretreatment of VRI induced blood vessel loss in developing zebrafish by inhibiting angiogenesis and increasing endothelial cell apoptosis, accompanied by down-regulation of kdr, kdrl and flt-1 genes expression. The VRI-induced blood vessel loss in zebrafish could be restored by post-treatment of calycosin, a cardiovascular protective isoflavone. Similarly, VRI induced cytotoxicity and apoptosis in HUVEC which could be rescued by calycosin post-treatment. Further investigation of the underlying mechanisms showed that the PI3K/AKT/Bad cell survival pathway was a main contributor of the vascular regenerative effect of calycosin. These findings indicated that the cardiovascular toxicity in anti-angiogenic therapy was mainly caused by insufficient endothelial cell survival, suggesting its essential role in vascular integrity, repair and regeneration. In addition, we showed that VRI-induced blood vessel loss in zebrafish represented a simple and effective in vivo model for studying vascular insufficiency and evaluating cancer drug vascular toxicities. - Highlights: • In vivo VRI model • Rescue effects of calycosin • Calycosin EC survival pathways

Uric acid promotes vascular stiffness, maladaptive inflammatory responses and proteinuria in western diet fed mice.

Science.gov (United States)

Aroor, Annayya R; Jia, Guanghong; Habibi, Javad; Sun, Zhe; Ramirez-Perez, Francisco I; Brady, Barron; Chen, Dongqing; Martinez-Lemus, Luis A; Manrique, Camila; Nistala, Ravi; Whaley-Connell, Adam T; Demarco, Vincent G; Meininger, Gerald A; Sowers, James R

2017-09-01

Aortic vascular stiffness has been implicated in the development of cardiovascular disease (CVD) and chronic kidney disease (CKD) in obese individuals. However, the mechanism promoting these adverse effects are unclear. In this context, promotion of obesity through consumption of a western diet (WD) high in fat and fructose leads to excess circulating uric acid. There is accumulating data implicating elevated uric acid in the promotion of CVD and CKD. Accordingly, we hypothesized that xanthine oxidase(XO) inhibition with allopurinol would prevent a rise in vascular stiffness and proteinuria in a translationally relevant model of WD-induced obesity. Four-week-old C57BL6/J male mice were fed a WD with excess fat (46%) and fructose (17.5%) with or without allopurinol (125mg/L in drinking water) for 16weeks. Aortic endothelial and extracellular matrix/vascular smooth muscle stiffness was evaluated by atomic force microscopy. Aortic XO activity, 3-nitrotyrosine (3-NT) and aortic endothelial sodium channel (EnNaC) expression were evaluated along with aortic expression of inflammatory markers. In the kidney, expression of toll like receptor 4 (TLR4) and fibronectin were assessed along with evaluation of proteinuria. XO inhibition significantly attenuated WD-induced increases in plasma uric acid, vascular XO activity and oxidative stress, in concert with reductions in proteinuria. Further, XO inhibition prevented WD-induced increases in aortic EnNaC expression and associated endothelial and subendothelial stiffness. XO inhibition also reduced vascular pro-inflammatory and maladaptive immune responses induced by consumption of a WD. XO inhibition also decreased WD-induced increases in renal TLR4 and fibronectin that associated proteinuria. Consumption of a WD leads to elevations in plasma uric acid, increased vascular XO activity, oxidative stress, vascular stiffness, and proteinuria all of which are attenuated with allopurinol administration. Copyright © 2017 Elsevier Inc

Self-Replenishing Vascularized Fouling-Release Surfaces

Energy Technology Data Exchange (ETDEWEB)

Howell, C; Vu, TL; Lin, JJ; Kolle, S; Juthani, N; Watson, E; Weaver, JC; Alvarenga, J; Aizenberg, J

2014-08-13

Inspired by the long-term effectiveness of living antifouling materials, we have developed a method for the self-replenishment of synthetic biofouling-release surfaces. These surfaces are created by either molding or directly embedding 3D vascular systems into polydimethylsiloxane (PDMS) and filling them with a silicone oil to generate a nontoxic oil-infused material. When replenished with silicone oil from an outside source, these materials are capable of self-lubrication and continuous renewal of the interfacial fouling-release layer. Under accelerated lubricant loss conditions, fully infused vascularized samples retained significantly more lubricant than equivalent nonvascularized controls. Tests of lubricant-infused PDMS in static cultures of the infectious bacteria Staphylococcus aureus and Escherichia coli as well as the green microalgae Botryococcus braunii, Chlamydomonas reinhardtii, Dunaliella sauna, and Nannochloropsis oculata showed a significant reduction in biofilm adhesion compared to PDMS and glass controls containing no lubricant. Further experiments on vascularized versus nonvascularized samples that had been subjected to accelerated lubricant evaporation conditions for up to 48 h showed significantly less biofilm adherence on the vascularized surfaces. These results demonstrate the ability of an embedded lubricant-filled vascular network to improve the longevity of fouling-release surfaces.

Closure of multiple types of K+ channels is necessar to induce changes in renal vascular resistance in vivo in rats

DEFF Research Database (Denmark)

Sørensen, Charlotte Mehlin; Giese, Isaiah; Braunstein, Thomas Hartig

2011-01-01

Inhibition of K(+) channels might mediate renal vasoconstriction. As inhibition of a single type of K(+) channel caused minor or no renal vasoconstriction in vivo in rats, we hypothesized that several classes of K(+) channels must be blocked to elicit renal vasoconstriction. We measured renal blo...

Management of vascular anomalies: Review of institutional management algorithm

Directory of Open Access Journals (Sweden)

Lalit K Makhija

2017-01-01

Full Text Available Introduction: Vascular anomalies are congenital lesions broadly categorised into vascular tumour (haemangiomas and vascular dysmorphogenesis (vascular malformation. The management of these difficult problems has lately been simplified by the biological classification and multidisciplinary approach. To standardise the treatment protocol, an algorithm has been devised. The study aims to validate the algorithm in terms of its utility and presents our experience in managing vascular anomalies. Materials and Methods: The biological classification of Mulliken and Glowacki was followed. A detailed algorithm for management of vascular anomalies has been devised in the department. The protocol is being practiced by us since the past two decades. The data regarding the types of lesions and treatment modality used were maintained. Results and Conclusion: This study was conducted from 2002 to 2012. A total of 784 cases of vascular anomalies were included in the study of which 196 were haemangiomas and 588 were vascular malformations. The algorithmic approach has brought an element of much-needed objectivity in the management of vascular anomalies. This has helped us to define the management of particular lesion considering its pathology, extent and aesthetic and functional consequences of ablation to a certain extent.

Molecular investigations of BK(Ca) channels and the modulatory beta-subunits in porcine basilar and middle cerebral arteries

DEFF Research Database (Denmark)

Johansson, Helle Wulf; Hay-Schmidt, Anders; Poulsen, Asser Nyander

2009-01-01

arteries using reverse transcription polymerase chain reaction (RT-PCR) and quantitative real-time PCR. Western blotting was used to detect immunoreactivity for the porcine BK(Ca) channel alpha-subunit and beta-subunit proteins. The BK(Ca) channel alpha-subunit RNA and protein distribution patterns were......Large conductance calcium-activated potassium (BK(Ca)) channels are fundamental in the regulation of cerebral vascular basal tone. We investigated the expression of the mRNA transcripts for the BK(Ca) channel and its modulatory beta-subunits (beta1-beta4) in porcine basilar and middle cerebral...... visualized using in situ hybridization and immunofluorescence studies, respectively. The study verified that the BK(Ca) channel alpha-subunit is located to smooth muscle cells of porcine basilar and middle cerebral arteries. The mRNA transcript for beta1-, beta2- and beta4-subunit were shown by RT...

Vascular pattern formation in plants.

Science.gov (United States)

Scarpella, Enrico; Helariutta, Ykä

2010-01-01

Reticulate tissue systems exist in most multicellular organisms, and the principles underlying the formation of cellular networks have fascinated philosophers, mathematicians, and biologists for centuries. In particular, the beautiful and varied arrangements of vascular tissues in plants have intrigued mankind since antiquity, yet the organizing signals have remained elusive. Plant vascular tissues form systems of interconnected cell files throughout the plant body. Vascular cells are aligned with one another along continuous lines, and vascular tissues differentiate at reproducible positions within organ environments. However, neither the precise path of vascular differentiation nor the exact geometry of vascular networks is fixed or immutable. Several recent advances converge to reconcile the seemingly conflicting predictability and plasticity of vascular tissue patterns. A control mechanism in which an apical-basal flow of signal establishes a basic coordinate system for body axis formation and vascular strand differentiation, and in which a superimposed level of radial organizing cues elaborates cell patterns, would generate a reproducible tissue configuration in the context of an underlying robust, self-organizing structure, and account for the simultaneous regularity and flexibility of vascular tissue patterns. Copyright 2010 Elsevier Inc. All rights reserved.

Ghrelin improves vascular autophagy in rats with vascular calcification.

Science.gov (United States)

Xu, Mingming; Liu, Lin; Song, Chenfang; Chen, Wei; Gui, Shuyan

2017-06-15

This study aimed to investigate whether ghrelin ameliorated vascular calcification (VC) through improving autophagy. VC model was induced by nicotine plus vitamin D 3 in rats and β-glycerophosphate in vascular smooth muscle cell (VSMC). Calcium deposition was detected by von Kossa staining or alizarin red S staining. ALP activity was also detected. Western blot was used to assess the protein expression. Ghrelin treatment attenuated the elevation of calcium deposition and ALP activity in VC model both in vivo and in vitro. Interesting, the protein levels of autophagy markers, LC3 and beclin1 were significantly upregulated by ghrelin in VC model. An autophagy inhibitor, 3-methyladenine blocks the ameliorative effect of ghrelin on VC. Furthermore, protein expressions of phosphate-AMPK were increased by ghrelin treatment both in calcified aorta and VSMC. The effect of ghrelin on autophagy induction and VC attenuation was prevented by AMPK inhibitor, compound C. Our results suggested that ghrelin improved autophagy through AMPK activation, which was resulted in VC amelioration. These data maybe throw light on prevention and therapy of VC. Copyright © 2016 Elsevier Inc. All rights reserved.

Vascular grading of angiogenesis

DEFF Research Database (Denmark)

Hansen, S; Grabau, D A; Sørensen, Flemming Brandt

2000-01-01

The study aimed to evaluate the prognostic value of angiogenesis by vascular grading of primary breast tumours, and to evaluate the prognostic impact of adding the vascular grade to the Nottingham Prognostic Index (NPI). The investigation included 836 patients. The median follow-up time was 11...... years and 4 months. The microvessels were immunohistochemically stained by antibodies against CD34. Angiogenesis was graded semiquantitatively by subjective scoring into three groups according to the expected number of microvessels in the most vascular tumour area. The vascular grading between observers...... for 24% of the patients, who had a shift in prognostic group, as compared to NPI, and implied a better prognostic dissemination. We concluded that the angiogenesis determined by vascular grading has independent prognostic value of clinical relevance for patients with breast cancer....

Vascular grading of angiogenesis

DEFF Research Database (Denmark)

Hansen, S; Grabau, D A; Sørensen, Flemming Brandt

2000-01-01

The study aimed to evaluate the prognostic value of angiogenesis by vascular grading of primary breast tumours, and to evaluate the prognostic impact of adding the vascular grade to the Nottingham Prognostic Index (NPI). The investigation included 836 patients. The median follow-up time was 11...... years and 4 months. The microvessels were immunohistochemically stained by antibodies against CD34. Angiogenesis was graded semiquantitatively by subjective scoring into three groups according to the expected number of microvessels in the most vascular tumour area. The vascular grading between observers...... impact for 24% of the patients, who had a shift in prognostic group, as compared to NPI, and implied a better prognostic dissemination. We concluded that the angiogenesis determined by vascular grading has independent prognostic value of clinical relevance for patients with breast cancer....

Apelin-13 inhibits large-conductance Ca2+-activated K+ channels in cerebral artery smooth muscle cells via a PI3-kinase dependent mechanism.

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Amit Modgil

Full Text Available Apelin-13 causes vasoconstriction by acting directly on APJ receptors in vascular smooth muscle (VSM cells; however, the ionic mechanisms underlying this action at the cellular level remain unclear. Large-conductance Ca(2+-activated K(+ (BKCa channels in VSM cells are critical regulators of membrane potential and vascular tone. In the present study, we examined the effect of apelin-13 on BK(Ca channel activity in VSM cells, freshly isolated from rat middle cerebral arteries. In whole-cell patch clamp mode, apelin-13 (0.001-1 μM caused concentration-dependent inhibition of BK(Ca in VSM cells. Apelin-13 (0.1 µM significantly decreased BK(Ca current density from 71.25 ± 8.14 pA/pF to 44.52 ± 7.10 pA/pF (n=14 cells, P<0.05. This inhibitory effect of apelin-13 was confirmed by single channel recording in cell-attached patches, in which extracellular application of apelin-13 (0.1 µM decreased the open-state probability (NPo of BK(Ca channels in freshly isolated VSM cells. However, in inside-out patches, extracellular application of apelin-13 (0.1 µM did not alter the NPo of BK(Ca channels, suggesting that the inhibitory effect of apelin-13 on BKCa is not mediated by a direct action on BK(Ca. In whole cell patches, pretreatment of VSM cells with LY-294002, a PI3-kinase inhibitor, markedly attenuated the apelin-13-induced decrease in BK(Ca current density. In addition, treatment of arteries with apelin-13 (0.1 µM significantly increased the ratio of phosphorylated-Akt/total Akt, indicating that apelin-13 significantly increases PI3-kinase activity. Taken together, the data suggest that apelin-13 inhibits BK(Ca channel via a PI3-kinase-dependent signaling pathway in cerebral artery VSM cells, which may contribute to its regulatory action in the control of vascular tone.

Structural and functional imaging for vascular targeted photodynamic therapy

Science.gov (United States)

Li, Buhong; Gu, Ying; Wilson, Brian C.

2017-02-01

Vascular targeted photodynamic therapy (V-PDT) has been widely used for the prevention or treatment of vascular-related diseases, such as localized prostate cancer, wet age-related macular degeneration, port wine stains, esophageal varices and bleeding gastrointestinal mucosal lesions. In this study, the fundamental mechanisms of vascular responses during and after V-PDT will be introduced. Based on the V-PDT treatment of blood vessels in dorsal skinfold window chamber model, the structural and functional imaging, which including white light microscopy, laser speckle imaging, singlet oxygen luminescence imaging, and fluorescence imaging for evaluating vascular damage will be presented, respectively. The results indicate that vessel constriction and blood flow dynamics could be considered as the crucial biomarkers for quantitative evaluation of vascular damage. In addition, future perspectives of non-invasive optical imaging for evaluating vascular damage of V-PDT will be discussed.

Hsc70 regulates cell surface ASIC2 expression and vascular smooth muscle cell migration.

Science.gov (United States)

Grifoni, Samira C; McKey, Susan E; Drummond, Heather A

2008-05-01

Recent studies suggest members of the degenerin (DEG)/epithelial Na(+) channel (ENaC)/acid-sensing ion channel (ASIC) protein family play an important role in vascular smooth muscle cell (VSMC) migration. In a previous investigation, we found suppression of a certain DEG/ENaC/ASIC member, ASIC2, increased VSMC chemotactic migration, raising the possibility that ASIC2 may play an inhibitory role. Because ASIC2 protein was retained in the cytoplasm, we reasoned increasing surface expression of ASIC2 might unmask the inhibitory role of ASIC2 in VSMC migration so we could test the hypothesis that ASIC2 inhibits VSMC migration. Therefore, we used the chemical chaperone glycerol to enhance ASIC2 expression. Glycerol 1) increased cytoplasm ASIC2 expression, 2) permitted detection of ASIC2 at the cell surface, and 3) inhibited platelet-derived growth factor (PDGF)-bb mediated VSMC migration. Furthermore, ASIC2 silencing completely abolished the inhibitory effect of glycerol on migration, suggesting upregulation of ASIC2 is responsible for glycerol-induced inhibition of VSMC migration. Because other investigators have shown that glycerol regulates ENaC/ASIC via interactions with a certain heat shock protein, heat shock protein 70 (Hsc70), we wanted to determine the importance of Hsc70 on ASIC2 expression in VSMCs. We found that Hsc70 silencing increases ASIC2 cell surface expression and inhibits VSMC migration, which is abolished by cosilencing ASIC2. These data demonstrate that Hsc70 inhibits ASIC2 expression, and, when the inhibitory effect of Hsc70 is removed, ASIC2 expression increases, resulting in reduced VSMC migration. Because VSMC migration contributes to vasculogenesis and remodeling following vascular injury, our findings raise the possibility that ASIC2-Hsc70 interactions may play a role in these processes.

Tributyltin contributes in reducing the vascular reactivity to phenylephrine in isolated aortic rings from female rats.

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Rodrigues, Samya Mere L; Ximenes, Carolina F; de Batista, Priscila R; Simões, Fabiana V; Coser, Pedro Henrique P; Sena, Gabriela C; Podratz, Priscila L; de Souza, Leticia N G; Vassallo, Dalton V; Graceli, Jones B; Stefanon, Ivanita

2014-03-21

Organotin compounds such as tributyltin (TBT) are used as antifouling paints by shipping companies. TBT inhibits the aromatase responsible for the transformation of testosterone into estrogen. Our hypothesis is that TBT modulates the vascular reactivity of female rats. Female Wistar rats were treated daily (Control; CONT) or TBT (100 ng/kg) for 15 days. Rings from thoracic aortas were incubated with phenylephrine (PHE, 10(-10)-10(-4) M) in the presence and absence of endothelium, and in the presence of N(G)-Nitro-L-Arginine Methyl Ester (L-NAME), tetraethylammonium (TEA) and apocynin. TBT decreased plasma levels of estrogen and the vascular response to PHE. In the TBT group, the vascular reactivity was increased in the absence of endothelium, L-NAME and TEA. The decrease in PHE reactivity during incubation with apocynin was more evident in the TBT group. The sensitivity to acetylcholine (ACh) and sodium nitroprusside (SNP) was reduced in the TBT group. TBT increased collagen, reduced α1-smooth muscle actin. Female rats treated with TBT for 15 days showed morphology alteration of the aorta and decreased their vascular reactivity, probably due to mechanisms dependent on nitric oxide (NO) bioavailability, K(+) channels and an increase in oxidative stress. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Activation of K{sup +} channels and Na{sup +}/K{sup +} ATPase prevents aortic endothelial dysfunction in 7-day lead-treated rats

Energy Technology Data Exchange (ETDEWEB)

Fiorim, Jonaina, E-mail: nanafiorim@hotmail.com [Department of Physiological Sciences, Federal University of Espirito Santo, Vitoria, ES (Brazil); Ribeiro Júnior, Rogério Faustino, E-mail: faustino43@oi.com.br [Department of Physiological Sciences, Federal University of Espirito Santo, Vitoria, ES (Brazil); Azevedo, Bruna Fernades, E-mail: brunafernandes.azevedo@gmail.com [Department of Physiological Sciences, Federal University of Espirito Santo, Vitoria, ES (Brazil); Simões, Maylla Ronacher, E-mail: yllars@hotmail.com [Department of Physiological Sciences, Federal University of Espirito Santo, Vitoria, ES (Brazil); Padilha, Alessandra Simão, E-mail: ale_spadilha@yahoo.com.br [Department of Physiological Sciences, Federal University of Espirito Santo, Vitoria, ES (Brazil); Stefanon, Ivanita, E-mail: ivanita@pq.cnpq.br [Department of Physiological Sciences, Federal University of Espirito Santo, Vitoria, ES (Brazil); Alonso, Maria Jesus, E-mail: mariajesus.alonso@urjc.es [Departamento de Ciencias de la Salud III, Universidad Rey Juan Carlos, Alcorcón (Spain); Salaices, Mercedes, E-mail: mercedes.salaices@uam.es [Departamento de Farmacología, Universidad Autónoma de Madrid, Instituto de Investigación Hospital Universitario La Paz (IdiPaz) (Spain); Vassallo, Dalton Valentim, E-mail: daltonv2@terra.com.br [Department of Physiological Sciences, Federal University of Espirito Santo, Vitoria, ES (Brazil)

2012-07-01

Seven day exposure to a low concentration of lead acetate increases nitric oxide bioavailability suggesting a putative role of K{sup +} channels affecting vascular reactivity. This could be an adaptive mechanism at the initial stages of toxicity from lead exposure due to oxidative stress. We evaluated whether lead alters the participation of K{sup +} channels and Na{sup +}/K{sup +}-ATPase (NKA) on vascular function. Wistar rats were treated with lead (1st dose 4 μg/100 g, subsequent doses 0.05 μg/100 g, im, 7 days) or vehicle. Lead treatment reduced the contractile response of aortic rings to phenylephrine (PHE) without changing the vasodilator response to acetylcholine (ACh) or sodium nitroprusside (SNP). Furthermore, this treatment increased basal O{sub 2}{sup −} production, and apocynin (0.3 μM), superoxide dismutase (150 U/mL) and catalase (1000 U/mL) reduced the response to PHE only in the treated group. Lead also increased aortic functional NKA activity evaluated by K{sup +}-induced relaxation curves. Ouabain (100 μM) plus L-NAME (100 μM), aminoguanidine (50 μM) or tetraethylammonium (TEA, 2 mM) reduced the K{sup +}-induced relaxation only in lead-treated rats. When aortic rings were precontracted with KCl (60 mM/L) or preincubated with TEA (2 mM), 4-aminopyridine (4-AP, 5 mM), iberiotoxin (IbTX, 30 nM), apamin (0.5 μM) or charybdotoxin (0.1 μM), the ACh-induced relaxation was more reduced in the lead-treated rats. Additionally, 4-AP and IbTX reduced the relaxation elicited by SNP more in the lead-treated rats. Results suggest that lead treatment promoted NKA and K{sup +} channels activation and these effects might contribute to the preservation of aortic endothelial function against oxidative stress. -- Highlights: ► Increased free radicals production ► Increased Na{sup +}/K{sup +} ATPase activity ► Promotes activation of the K{sup +} channels and reduced vascular reactivity ► These effects preserve endothelial function against oxidative

Mechanism of the modulation of BK potassium channel complexes with different auxiliary subunit compositions by the omega-3 fatty acid DHA.

Science.gov (United States)

Hoshi, Toshinori; Tian, Yutao; Xu, Rong; Heinemann, Stefan H; Hou, Shangwei

2013-03-19

Large-conductance Ca(2+)- and voltage-activated K(+) (BK) channels are well known for their functional versatility, which is bestowed in part by their rich modulatory repertoire. We recently showed that long-chain omega-3 polyunsaturated fatty acids such as docosahexaenoic acid (DHA) found in oily fish lower blood pressure by activating vascular BK channels made of Slo1+β1 subunits. Here we examined the action of DHA on BK channels with different auxiliary subunit compositions. Neuronal Slo1+β4 channels were just as well activated by DHA as vascular Slo1+β1 channels. In contrast, the stimulatory effect of DHA was much smaller in Slo1+β2, Slo1+LRRC26 (γ1), and Slo1 channels without auxiliary subunits. Mutagenesis of β1, β2, and β4 showed that the large effect of DHA in Slo1+β1 and Slo1+β4 is conferred by the presence of two residues, one in the N terminus and the other in the first transmembrane segment of the β1 and β4 subunits. Transfer of this amino acid pair from β1 or β4 to β2 introduces a large response to DHA in Slo1+β2. The presence of a pair of oppositely charged residues at the aforementioned positions in β subunits is associated with a large response to DHA. The Slo1 auxiliary subunits are expressed in a highly tissue-dependent fashion. Thus, the subunit composition-dependent stimulation by DHA demonstrates that BK channels are effectors of omega-3 fatty acids with marked tissue specificity.

The effect of signal variability on the histograms of anthropomorphic channel outputs: factors resulting in non-normally distributed data

Science.gov (United States)

Elshahaby, Fatma E. A.; Ghaly, Michael; Jha, Abhinav K.; Frey, Eric C.

2015-03-01

Model Observers are widely used in medical imaging for the optimization and evaluation of instrumentation, acquisition parameters and image reconstruction and processing methods. The channelized Hotelling observer (CHO) is a commonly used model observer in nuclear medicine and has seen increasing use in other modalities. An anthropmorphic CHO consists of a set of channels that model some aspects of the human visual system and the Hotelling Observer, which is the optimal linear discriminant. The optimality of the CHO is based on the assumption that the channel outputs for data with and without the signal present have a multivariate normal distribution with equal class covariance matrices. The channel outputs result from the dot product of channel templates with input images and are thus the sum of a large number of random variables. The central limit theorem is thus often used to justify the assumption that the channel outputs are normally distributed. In this work, we aim to examine this assumption for realistically simulated nuclear medicine images when various types of signal variability are present.

Pathophysiology of Headaches with a Prominent Vascular Component

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Juan A Pareja

1996-01-01

Full Text Available Vascular changes, whether preliminary or secondary, seem to accompany most headaches. The literature concerning pathophysiological mechanisms in headaches where vascular phenomena are a major, integral part, ie, migraine and cluster headache syndrome, is reviewed and the most common forms of headache associated with cerebrovascular disease are discussed. Emphasis is placed on the vascular phenomena and on the abundant hypotheses and theories regarding headache mechanisms. This review also presents alternative explanatory models, and compares the available anatomical, physiological and biochemical results.

Powerful vascular protection by combining cilnidipine with valsartan in stroke-prone, spontaneously hypertensive rats

OpenAIRE

Takai, Shinji; Jin, Denan; Aritomi, Shizuka; Niinuma, Kazumi; Miyazaki, Mizuo

2012-01-01

Cilnidipine is an L- and N-type calcium channel blocker (CCB), and amlodipine is an L-type CCB. Valsartan (10?mg?kg?1), valsartan (10?mg?kg?1) and amlodipine (1?mg kg?1), and valsartan (10?mg?kg?1) and cilnidipine (1?mg?kg?1) were administered once daily for 2 weeks to stroke-prone, spontaneously hypertensive rats (SHR-SPs). Blood pressure was significantly reduced by valsartan, and it was further reduced by the combination therapies. Vascular endothelial dysfunction was significantly attenua...

Biomimicry, vascular restenosis and coronary stents.

Science.gov (United States)

Schwartz, R S; van der Giessen, W J; Holmes, D R

1998-01-01

Biomimicry is in its earliest stages and is being considered in the realm of tissue engineering. If arterial implants are to limit neointimal thickening, purely passive structures cannot succeed. Bioactivity must be present, either by pharmacologic intervention or by fabricating a 'living stent' that contains active cellular material. As tissue engineering evolves, useful solutions will emerge from applying this knowledge directly to vascular biologic problems resulting from angioplasty, stenting, and vascular prosthesis research.

Arteriographic evaluation, in the perispheric vascular trauma

International Nuclear Information System (INIS)

Patino, Jairo Hernando; Granados, Ana Maria; Lopera B, Jorge; Prada W, Angela Maria

1993-01-01

136 patients were angiographically studied under the suspicion of perispheric vascular lesion submitted to the radiology department of the San Vicente de Paul University Hospital (H.U.S.VP.) Medellin Colombia. The majority of the patients were young with wounds caused by gunshots (79.4%). the must frequent angiographic indication was the proximity of the wound to a vascular path (44.5%). 63% of the patients with angiography indicative of abnormality needed surgery from which 21% were because of the proximity of the wound to a vascular path and 76% because of the mayor findings when admitted to the hospital. the possible complications as a result of the angiographic procedure were revised only find inc two mayor reactions to the contrast media. there were no late complications. Angiography is highlighting sensitive (100%) specific (98.5%) and secure in the evaluation of patients with perispheric vascular trauma. Due to the high number of false negatives when the physical examination is performed, every patient with a wound near a vascular path must be evaluated angiographically

Channel characteristics and coordination in three-echelon dual-channel supply chain

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Saha, Subrata

2016-02-01

We explore the impact of channel structure on the manufacturer, the distributer, the retailer and the entire supply chain by considering three different channel structures in radiance of with and without coordination. These structures include a traditional retail channel and two manufacturer direct channels with and without consistent pricing. By comparing the performance of the manufacturer, the distributer and the retailer, and the entire supply chain in three different supply chain structures, it is established analytically that, under some conditions, a dual channel can outperform a single retail channel; as a consequence, a coordination mechanism is developed that not only coordinates the dual channel but also outperforms the non-cooperative single retail channel. All the analytical results are further analysed through numerical examples.

FGF-dependent metabolic control of vascular development

Science.gov (United States)

Yu, Pengchun; Alves, Tiago C.; Fang, Jennifer S.; Xie, Yi; Zhu, Jie; Chen, Zehua; De Smet, Frederik; Zhang, Jiasheng; Jin, Suk-Won; Sun, Lele; Sun, Hongye; Kibbey, Richard G.; Hirschi, Karen K.; Hay, Nissim; Carmeliet, Peter; Chittenden, Thomas W.; Eichmann, Anne; Potente, Michael; Simons, Michael

2017-01-01

Blood and lymphatic vasculatures are intimately involved in tissue oxygenation and fluid homeostasis maintenance. Assembly of these vascular networks involves sprouting, migration and proliferation of endothelial cells. Recent studies have suggested that changes in cellular metabolism are of importance to these processes1. While much is known about vascular endothelial growth factor (VEGF)-dependent regulation of vascular development and metabolism2,3, little is understood about the role of fibroblast growth factors (FGFs) in this context4. Here we identify FGF receptor (FGFR) signaling as a critical regulator of vascular development. This is achieved by FGF-dependent control of c-MYC (MYC) expression that, in turn, regulates expression of the glycolytic enzyme hexokinase 2 (HK2). A decrease in HK2 levels in the absence of FGF signaling inputs results in decreased glycolysis leading to impaired endothelial cell proliferation and migration. Pan-endothelial- and lymphatic-specific Hk2 knockouts phenocopy blood and/or lymphatic vascular defects seen in Fgfr1/r3 double mutant mice while HK2 overexpression partially rescues the defects caused by suppression of FGF signaling. Thus, FGF-dependent regulation of endothelial glycolysis is a pivotal process in developmental and adult vascular growth and development. PMID:28467822

The evolution of development of vascular cambia and secondary growth

Science.gov (United States)

Andrew Groover; Rachel Spicer

2010-01-01

Secondary growth from vascular cambia results in radial, woody growth of stems. The innovation of secondary vascular development during plant evolution allowed the production of novel plant forms ranging from massive forest trees to flexible, woody lianas. We present examples of the extensive phylogenetic variation in secondary vascular growth and discuss current...

Is there a role for T-type Ca2+ channels in regulation of vasomotor tone in mesenteric arterioles?

DEFF Research Database (Denmark)

Jensen, Lars Jørn; Holstein-Rathlou, Niels-Henrik

2009-01-01

The largest peripheral blood pressure drop occurs in terminal arterioles (microm lumen diameter). L-type voltage-dependent Ca2+ channels (VDCCs) are considered the primary pathway for Ca2+ influx during physiologic activation of vascular smooth muscle cells (VSMC). Recent evidence suggests...... was predominantly expressed in endothelial cells. Voltage-dependent Ca2+ entry was inhibited by the new specific T-type blockers R(-)-efonidipine and NNC 55-0396. The effect of NNC 55-0396 persisted in depolarized arterioles, suggesting an unusually high activation threshold of mesenteric T-type channels. T...... that T-type VDCCs are expressed in renal afferent and efferent arterioles, mesenteric arterioles, and skeletal muscle arterioles. T-type channels are small-conductance, low voltage-activated, fast-inactivating channels. Thus, their role in supplying Ca2+ for contraction of VSMC has been disputed. However...

An information-guided channel-hopping scheme for block-fading channels with estimation errors

KAUST Repository

Yang, Yuli

2010-12-01

Information-guided channel-hopping technique employing multiple transmit antennas was previously proposed for supporting high data rate transmission over fading channels. This scheme achieves higher data rates than some mature schemes, such as the well-known cyclic transmit antenna selection and space-time block coding, by exploiting the independence character of multiple channels, which effectively results in having an additional information transmitting channel. Moreover, maximum likelihood decoding may be performed by simply decoupling the signals conveyed by the different mapping methods. In this paper, we investigate the achievable spectral efficiency of this scheme in the case of having channel estimation errors, with optimum pilot overhead for minimum meansquare error channel estimation, when transmitting over blockfading channels. Our numerical results further substantiate the robustness of the presented scheme, even with imperfect channel state information. ©2010 IEEE.

Inactivation of Mechanically Activated Piezo1 Ion Channels Is Determined by the C-Terminal Extracellular Domain and the Inner Pore Helix

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Jason Wu

2017-11-01

Full Text Available Piezo proteins form mechanically activated ion channels that are responsible for our sense of light touch, proprioception, and vascular blood flow. Upon activation by mechanical stimuli, Piezo channels rapidly inactivate in a voltage-dependent manner through an unknown mechanism. Inactivation of Piezo channels is physiologically important, as it modulates overall mechanical sensitivity, gives rise to frequency filtering of repetitive mechanical stimuli, and is itself the target of numerous human disease-related channelopathies that are not well understood mechanistically. Here, we identify the globular C-terminal extracellular domain as a structure that is sufficient to confer the time course of inactivation and a single positively charged lysine residue at the adjacent inner pore helix as being required for its voltage dependence. Our results are consistent with a mechanism for inactivation that is mediated through voltage-dependent conformations of the inner pore helix and allosteric coupling with the C-terminal extracellular domain.

The surge of flavonoids as novel, fine regulators of cardiovascular Cav channels.

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Fusi, Fabio; Spiga, Ottavia; Trezza, Alfonso; Sgaragli, Giampietro; Saponara, Simona

2017-02-05

Ion channels underlie a wide variety of physiological processes that involve rapid changes in cell dynamics, such as cardiac and vascular smooth muscle contraction. Overexpression or dysfunction of these membrane proteins are the basis of many cardiovascular diseases that represent the leading cause of morbidity and mortality for human beings. In the last few years, flavonoids, widely distributed in the plant kingdom, have attracted the interest of many laboratories as an emerging class of fine ion, in particular Ca v , channels modulators. Pieces of in vitro evidence for direct as well as indirect effects exerted by various flavonoids on ion channel currents are now accumulating in the scientific literature. This activity may be responsible, at least in part, for the beneficial and protective effects of dietary flavonoids toward cardiovascular diseases highlighted in several epidemiological studies. Here we examine numerous studies aimed at analysing this feature of flavonoids, focusing on the mechanisms that promote their sometimes controversial activities at cardiovascular Ca v channels. New methodological approaches, such as molecular modelling and docking to Ca v 1.2 channel α 1c subunit, used to elucidate flavonoids intrinsic mechanism of action, are introduced. Moreover, flavonoid-membrane interaction, bioavailability, and antioxidant activity are taken into account and discussed. Copyright © 2016 Elsevier B.V. All rights reserved.

A microfluidic device for study of the effect of tumor vascular structures on the flow field and HepG2 cellular flow behaviors.

Science.gov (United States)

Ke, Ming; Cai, Shaoxi; Zou, Misha; Zhao, Yi; Li, Bo; Chen, Sijia; Chen, Longcong

2018-01-29

To build a microfluidic device with various morphological features of the tumor vasculature for study of the effects of tumor vascular structures on the flow field and tumor cellular flow behaviors. The designed microfluidic device was able to approximatively simulate the in vivo structures of tumor vessels and the flow within it. In this models, the influences of the angle of bifurcation, the number of branches, and the narrow channels on the flow field and the influence of vorticity on the retention of HepG2 cells were significant. Additionally, shear stress below physiological conditions of blood circulation has considerable effect on the formation of the lumen-like structures (LLSs) of HepG2 cells. These results can provide some data and reference in the understanding of the interaction between hemorheological properties and tumor vascular structures in solid tumors. Copyright © 2018. Published by Elsevier Inc.

Mechanisms of vegetation-induced channel narrowing of an unregulated canyon river: Results from a natural field-scale experiment

Science.gov (United States)

Manners, Rebecca B.; Schmidt, John C.; Scott, Michael L.

2014-04-01

The lower Yampa River in Yampa Canyon, western Colorado serves as a natural, field-scale experiment, initiated when the invasive riparian plant, tamarisk (Tamarix spp.), colonized an unregulated river. In response to tamarisk's rapid invasion, the channel narrowed by 6% in the widest reaches since 1961. Taking advantage of this unique setting, we reconstructed the geomorphic and vegetation history in order to identify the key mechanisms for which, in the absence of other environmental perturbations, vegetation alters fluvial processes that result in a narrower channel. From our reconstruction, we identified a distinct similarity in the timing and magnitude of tamarisk encroachment and channel change, albeit with a lag in the channel response, thus suggesting tamarisk as the driving force. Within a decade of establishment, tamarisk effectively trapped sediment and, as a result, increased floodplain construction rates. Increasing tamarisk coverage over time also reduced the occurrence of floodplain stripping. Tamarisk recruitment was driven by both hydrologic and hydraulic variables, and the majority of tamarisk plants (84%) established below the stage of the 2-year flood. Thus, upon establishment nearly all plants regularly interact with the flow and sediment transport field. Our analyses were predicated on the hypothesis that the flow regime of the Yampa River was stationary, and that only the riparian vegetation community had changed. While not heavily impacted by water development, we determined that some aspects of the flow regime have shifted. However, this shift, which involved the clustering in time of extremely wet and dry years, did not influence fluvial processes directly. Instead these changes directly impacted riparian vegetation and changes in vegetation cover, in turn, altered fluvial processes. Today, the rate of channel change and new tamarisk recruitment is small. We believe that the rapid expansion of tamarisk and related floodplain construction

4-Aminopyridine: a pan voltage-gated potassium channel inhibitor that enhances K7.4 currents and inhibits noradrenaline-mediated contraction of rat mesenteric small arteries

DEFF Research Database (Denmark)

Khammy, Makhala M; Kim, Sukhan; Bentzen, Bo H

2018-01-01

has not been systematically studied. The aim of this study was to investigate the pharmacological activity of 4-AP on Kv7.4 and Kv7.5 channels and characterize the effect of 4-AP on rat resistance arteries. EXPERIMENTAL APPROACH: Voltage clamp experiments were performed on Xenopus laevis oocytes......BACKGROUND AND PURPOSE: Kv7.4 and Kv7.5 channels are regulators of vascular tone. 4-Aminopyridine (4-AP) is considered a broad inhibitor of voltage-gated potassium (KV) channels, with little inhibitory effect on Kv7 family members at mmol concentrations. However, the effect of 4-AP on Kv7 channels...

Proatherogenic pathways leading to vascular calcification

International Nuclear Information System (INIS)

Mazzini, Michael J.; Schulze, P. Christian

2006-01-01

Cardiovascular disease is the leading cause of morbidity and mortality in the western world and atherosclerosis is the major common underlying disease. The pathogenesis of atherosclerosis involves local vascular injury, inflammation and oxidative stress as well as vascular calcification. Vascular calcification has long been regarded as a degenerative process leading to mineral deposition in the vascular wall characteristic for late stages of atherosclerosis. However, recent studies identified vascular calcification in early stages of atherosclerosis and its occurrence has been linked to clinical events in patients with cardiovascular disease. Its degree correlates with local vascular inflammation and with the overall impact and the progression of atherosclerosis. Over the last decade, diverse and highly regulated molecular signaling cascades controlling vascular calcification have been described. Local and circulating molecules such as osteopontin, osteoprogerin, leptin and matrix Gla protein were identified as critical regulators of vascular calcification. We here review the current knowledge on molecular pathways of vascular calcification and their relevance for the progression of cardiovascular disease

Protein kinase A and C regulate leak potassium currents in freshly isolated vascular myocytes from the aorta.

Directory of Open Access Journals (Sweden)

Sébastien Hayoz

Full Text Available We tested the hypothesis that protein kinase A (PKA inhibits K2P currents activated by protein kinase C (PKC in freshly isolated aortic myocytes. PDBu, the PKC agonist, applied extracellularly, increased the amplitude of the K2P currents in the presence of the "cocktail" of K(+ channel blockers. Gö 6976 significantly reduced the increase of the K2P currents by PDBu suggesting the involvement of either α or β isoenzymes of PKC. We found that forskolin, or membrane permeable cAMP, did not inhibit K2P currents activated by the PKC. However, when PKA agonists were added prior to PDBu, they produced a strong decrease in the K2P current amplitudes activated by PKC. Inhibition of PDBu-elicited K2P currents by cAMP agonists was not prevented by the treatment of vascular smooth muscle cells with PKA antagonists (H-89 and Rp-cAMPs. Zn(2+ and Hg(2+ inhibited K2P currents in one population of cells, produced biphasic responses in another population, and increased the amplitude of the PDBu-elicited K(+ currents in a third population of myocytes, suggesting expression of several K2P channel types. We found that cAMP agonists inhibited biphasic responses and increase of amplitude of the PDBu-elicited K2P currents produced by Zn(2+ and Hg(2. 6-Bnz-cAMp produced a significantly altered pH sensitivity of PDBu-elicited K2P-currents, suggesting the inhibition of alkaline-activated K2P-currents. These results indicate that 6-Bnz-cAMP and other cAMP analogs may inhibit K2P currents through a PKA-independent mechanism. cAMP analogs may interact with unidentified proteins involved in K2P channel regulation. This novel cellular mechanism could provide insights into the interplay between PKC and PKA pathways that regulate vascular tone.

Cell proliferation along vascular islands during microvascular network growth

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Kelly-Goss Molly R

2012-06-01

Full Text Available Abstract Background Observations in our laboratory provide evidence of vascular islands, defined as disconnected endothelial cell segments, in the adult microcirculation. The objective of this study was to determine if vascular islands are involved in angiogenesis during microvascular network growth. Results Mesenteric tissues, which allow visualization of entire microvascular networks at a single cell level, were harvested from unstimulated adult male Wistar rats and Wistar rats 3 and 10 days post angiogenesis stimulation by mast cell degranulation with compound 48/80. Tissues were immunolabeled for PECAM and BRDU. Identification of vessel lumens via injection of FITC-dextran confirmed that endothelial cell segments were disconnected from nearby patent networks. Stimulated networks displayed increases in vascular area, length density, and capillary sprouting. On day 3, the percentage of islands with at least one BRDU-positive cell increased compared to the unstimulated level and was equal to the percentage of capillary sprouts with at least one BRDU-positive cell. At day 10, the number of vascular islands per vascular area dramatically decreased compared to unstimulated and day 3 levels. Conclusions These results show that vascular islands have the ability to proliferate and suggest that they are able to incorporate into the microcirculation during the initial stages of microvascular network growth.

Vascular Remodeling in Experimental Hypertension

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Norma R. Risler

2005-01-01

Full Text Available The basic hemodynamic abnormality in hypertension is an increased peripheral resistance that is due mainly to a decreased vascular lumen derived from structural changes in the small arteries wall, named (as a whole vascular remodeling. The vascular wall is an active, flexible, and integrated organ made up of cellular (endothelial cells, smooth muscle cells, adventitia cells, and fibroblasts and noncellular (extracellular matrix components, which in a dynamic way change shape or number, or reorganize in response to physiological and pathological stimuli, maintaining the integrity of the vessel wall in physiological conditions or participating in the vascular changes in cardiovascular diseases such as hypertension. Research focused on new signaling pathways and molecules that can participate in the mechanisms of vascular remodeling has provided evidence showing that vascular structure is not only affected by blood pressure, but also by mechanisms that are independent of the increased pressure. This review will provide an overview of the evidence, explaining some of the pathophysiologic mechanisms participating in the development of the vascular remodeling, in experimental models of hypertension, with special reference to the findings in spontaneously hypertensive rats as a model of essential hypertension, and in fructose-fed rats as a model of secondary hypertension, in the context of the metabolic syndrome. The understanding of the mechanisms producing the vascular alterations will allow the development of novel pharmacological tools for vascular protection in hypertensive disease.

Upregulation of SK3 and IK1 channels contributes to the enhanced endothelial calcium signaling and the preserved coronary relaxation in obese Zucker rats.

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Belén Climent

Full Text Available Endothelial small- and intermediate-conductance KCa channels, SK3 and IK1, are key mediators in the endothelium-derived hyperpolarization and relaxation of vascular smooth muscle and also in the modulation of endothelial Ca2+ signaling and nitric oxide (NO release. Obesity is associated with endothelial dysfunction and impaired relaxation, although how obesity influences endothelial SK3/IK1 function is unclear. Therefore we assessed whether the role of these channels in the coronary circulation is altered in obese animals.In coronary arteries mounted in microvascular myographs, selective blockade of SK3/IK1 channels unmasked an increased contribution of these channels to the ACh- and to the exogenous NO- induced relaxations in arteries of Obese Zucker Rats (OZR compared to Lean Zucker Rats (LZR. Relaxant responses induced by the SK3/IK1 channel activator NS309 were enhanced in OZR and NO- endothelium-dependent in LZR, whereas an additional endothelium-independent relaxant component was found in OZR. Fura2-AM fluorescence revealed a larger ACh-induced intracellular Ca2+ mobilization in the endothelium of coronary arteries from OZR, which was inhibited by blockade of SK3/IK1 channels in both LZR and OZR. Western blot analysis showed an increased expression of SK3/IK1 channels in coronary arteries of OZR and immunohistochemistry suggested that it takes place predominantly in the endothelial layer.Obesity may induce activation of adaptive vascular mechanisms to preserve the dilator function in coronary arteries. Increased function and expression of SK3/IK1 channels by influencing endothelial Ca2+ dynamics might contribute to the unaltered endothelium-dependent coronary relaxation in the early stages of obesity.

Evaluation of cell viability and functionality in vessel-like bioprintable cell-laden tubular channels.

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Yu, Yin; Zhang, Yahui; Martin, James A; Ozbolat, Ibrahim T

2013-09-01

Organ printing is a novel concept recently introduced in developing artificial three-dimensional organs to bridge the gap between transplantation needs and organ shortage. One of the major challenges is inclusion of blood-vessellike channels between layers to support cell viability, postprinting functionality in terms of nutrient transport, and waste removal. In this research, we developed a novel and effective method to print tubular channels encapsulating cells in alginate to mimic the natural vascular system. An experimental investigation into the influence on cartilage progenitor cell (CPCs) survival, and the function of printing parameters during and after the printing process were presented. CPC functionality was evaluated by checking tissue-specific genetic marker expression and extracellular matrix production. Our results demonstrated the capability of direct fabrication of cell-laden tubular channels by our newly designed coaxial nozzle assembly and revealed that the bioprinting process could induce quantifiable cell death due to changes in dispensing pressure, coaxial nozzle geometry, and biomaterial concentration. Cells were able to recover during incubation, as well as to undergo differentiation with high-level cartilage-associated gene expression. These findings may not only help optimize our system but also can be applied to biomanufacturing of 3D functional cellular tissue engineering constructs for various organ systems.

Vinpocetine Attenuates the Osteoblastic Differentiation of Vascular Smooth Muscle Cells.

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Yun-Yun Ma

Full Text Available Vascular calcification is an active process of osteoblastic differentiation of vascular smooth muscle cells; however, its definite mechanism remains unknown. Vinpocetine, a derivative of the alkaloid vincamine, has been demonstrated to inhibit the high glucose-induced proliferation of vascular smooth muscle cells; however, it remains unknown whether vinpocetine can affect the osteoblastic differentiation of vascular smooth muscle cells. We hereby investigated the effect of vinpocetine on vascular calcification using a beta-glycerophosphate-induced cell model. Our results showed that vinpocetine significantly reduced the osteoblast-like phenotypes of vascular smooth muscle cells including ALP activity, osteocalcin, collagen type I, Runx2 and BMP-2 expression as well as the formation of mineralized nodule. Vinpocetine, binding to translocation protein, induced phosphorylation of extracellular signal-related kinase and Akt and thus inhibited the translocation of nuclear factor-kappa B into the nucleus. Silencing of translocator protein significantly attenuated the inhibitory effect of vinpocetine on osteoblastic differentiation of vascular smooth muscle cells. Taken together, vinpocetine may be a promising candidate for the clinical therapy of vascular calcification.

Vascular Adventitia Calcification and Its Underlying Mechanism.

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Na Li

Full Text Available Previous research on vascular calcification has mainly focused on the vascular intima and media. However, we show here that vascular calcification may also occur in the adventitia. The purpose of this work is to help elucidate the pathogenic mechanisms underlying vascular calcification. The calcified lesions were examined by Von Kossa staining in ApoE-/- mice which were fed high fat diets (HFD for 48 weeks and human subjects aged 60 years and older that had died of coronary heart disease, heart failure or acute renal failure. Explant cultured fibroblasts and smooth muscle cells (SMCswere obtained from rat adventitia and media, respectively. After calcification induction, cells were collected for Alizarin Red S staining. Calcified lesions were observed in the aorta adventitia and coronary artery adventitia of ApoE-/-mice, as well as in the aorta adventitia of human subjects examined. Explant culture of fibroblasts, the primary cell type comprising the adventitia, was successfully induced for calcification after incubation with TGF-β1 (20 ng/ml + mineralization media for 4 days, and the phenotype conversion vascular adventitia fibroblasts into myofibroblasts was identified. Culture of SMCs, which comprise only a small percentage of all cells in the adventitia, in calcifying medium for 14 days resulted in significant calcification.Vascular calcification can occur in the adventitia. Adventitia calcification may arise from the fibroblasts which were transformed into myofibroblasts or smooth muscle cells.

Clinical application of the amplatzer vascular plug in the embolization of vascular malformations associated with congenital heart diseasee

International Nuclear Information System (INIS)

Pan Xin; Wang Cheng; Lu Jing; Wu Weihua; Fang Weiyi

2009-01-01

Objective: To evaluate the clinical efficacy of percutaneous transcatheter embolization by using Amplatzer vascular plug (AVP) for the treatment of vascular malformations associated with congenital heart diseases. Methods: During the period of June 2006-June 2008, 12 patients with congenital heart disease accompanied by vascular malformations received transcatheter occlusion of the anomalous vessels with AVP. The vascular malformations included solitary or multiple saccular pulmonary arteriovenous malformation (n = 7), coronary artery fistula (n = 2) and major aortopulmonary collaterals concomitant with severe Fallot' s tetralogy (n = 3). All patients were screened with transthoracic echocardiography (TTE) and thoracic CT angiography (CTA), and all the diagnoses were confirmed by routine cardioangiography. Results: Transcatheter occlusion of vascular malformations with AVP was successfully accomplished in all 12 patients. An angiographic check immediately after the procedure showed that complete occlusion was obtained in all patients and no embolism,migration or residual shunt were seen. Sixteen anomalous vessels were occluded. The mean internal diameter of these vessels was (5.2 ± 1.9) mm,while the mean diameter of AVP used was (9.2 ± 2.4) mm. After the operation (mean 3 months), the follow-up echocardiography and/or thoracic CT angiography showed that in all patients the occlusion remained in satisfactory condition and no residual shunt was found. Conclusions: Percutaneous transcatheter closure of congenital vascular malformations with AVP is technically feasible and clinically effective, this treatment can markedly improve patient's living quality and it is well worth extending its clinical application. (authors)

The shallow-water Asellota (Crustacea: Isopoda from the Beagle Channel: Preliminary taxonomic and zoogeographical results

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Brenda Lía Doti

2005-12-01

Full Text Available The shallow-water Asellota from the Beagle Channel were investigated, based on material collected at four localities in 2001-2002. A total of 3,124 asellotes were sorted, and three new species and 12 new records of distribution were reported. The Paramunnidae showed the highest species diversity and abundance (11 species and 1,463 specimens. The present research raises the number of species known from the Beagle Channel to 23; of these, 16 were previously reported from the Magellan Straits, representing 69% of similarity. Based on the present results and published data, the faunistic affinities for the shallow-water Asellota was 30% between the Magellan region and the Scotia Arc, and 26% between the Magellan region and the Antarctic Peninsula.

Design, synthesis and biological evaluation of novel ring-opened cromakalim analogues with relaxant effects on vascular and respiratory smooth muscles and as stimulators of elastin synthesis.

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Bouhedja, Mourad; Peres, Basile; Fhayli, Wassim; Ghandour, Zeinab; Boumendjel, Ahcène; Faury, Gilles; Khelili, Smail

2018-01-20

Two new series of ring-opened analogues of cromakalim bearing sulfonylurea moieties (series A: with N-unmethylated sulfonylureas, series B: with N-methylated sulfonylureas) were synthesized and tested as relaxants of vascular and respiratory smooth muscles (rat aorta and trachea, respectively). Ex vivo biological evaluations indicated that the most active compounds, belonging to series B, displayed a marked vasorelaxant activity on endothelium-intact aortic rings and the trachea. A majority of series B compounds exhibited a higher vasorelaxant activity (EC 50  stronger relaxant effects on the trachea than the reference compound cromakalim (EC 50  = 124 μM), in particular compounds B4, B7 and B16 (EC 50   57 μM for all, and EC 50  > 200 μM for a majority of them), but some of them showed an interesting relaxing effect on trachea (i.e. A15 and A33, EC 50  = 30 μM). The most potent compounds of both series, i.e. A15, A33 and B16, tested on aortic rings in the presence of glibenclamide or 80 mM KCl, suggested that they acted as voltage-gated Ca 2+ channel blockers, like verapamil, instead of being ATP-potassium channel activators, as is cromakalim, the parent molecule. Further investigations on cultured vascular smooth muscle cells showed a strong stimulating effect on elastin synthesis, especially compound B16, which was more active at 20 μM than diazoxide, a reference ATP-sensitive potassium channel activator. Taken together, our results show that the N-methylation of the sulfonylurea moieties of ring-opened cromakalim analogues led to new compounds blocking calcium-gated channels, which had a major impact on the arterial and tracheal activities as well as selectivity. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

Vascular neurology nurse practitioner provision of telemedicine consultations.

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Demaerschalk, Bart M; Kiernan, Terri-Ellen J; Investigators, Starr

2010-01-01

Objective. The objective was to define and evaluate a role for the Vascular Neurology-Nurse Practitioner (VN-NP) in the delivery of telemedicine consultations in partnership with a vascular neurologist. Methods. Prospective stroke alert patients at participating hospitals underwent a two-way audio video telemedicine consultation with a VN-NP at a remotely located stroke center in partnership with a vascular neurologist. Demographic information, National Institutes of Health Stroke Scale (NIHSS) scores, diagnoses, CT contraindications to thrombolysis, thrombolysis eligibility, and time interval data were collected. The inter-rater agreement between VN-NP and vascular neurologist assessments was calculated. Results. Ten patients were evaluated. Four were determined to have ischemic stroke, one had a transient ischemic attack, two had intracerebral hemorrhages, and three were stroke mimics. Overall, three patients received thrombolysis. The inter-rater agreement between VN-NP and vascular neurologist assessments were excellent, ranging from 0.9 to 1.0. The duration of VN-NP consultation was 53.2 +/- 9.0 minutes, which included the vascular neurologist supervisory evaluation time of 12.0 +/- 9.6 minutes. Conclusion. This study illustrated that a stroke center VN-NP, in partnership with a vascular neurologist, could deliver timely telemedicine consultations, accurate diagnoses, and correct treatments in acute stroke patients who presented to remotely located rural emergency departments within a hub and spoke network. VN-NPs may fulfill the role of a telestroke provider.

Pediatric central nervous system vascular malformations

Energy Technology Data Exchange (ETDEWEB)

Burch, Ezra A. [Brigham and Women' s Hospital, Department of Radiology, Boston, MA (United States); Orbach, Darren B. [Boston Children' s Hospital, Neurointerventional Radiology, Boston, MA (United States)

2015-09-15

Pediatric central nervous system (CNS) vascular anomalies include lesions found only in the pediatric population and also the full gamut of vascular lesions found in adults. Pediatric-specific lesions discussed here include infantile hemangioma, vein of Galen malformation and dural sinus malformation. Some CNS vascular lesions that occur in adults, such as arteriovenous malformation, have somewhat distinct manifestations in children, and those are also discussed. Additionally, children with CNS vascular malformations often have associated broader vascular conditions, e.g., PHACES (posterior fossa anomalies, hemangioma, arterial anomalies, cardiac anomalies, eye anomalies and sternal anomalies), hereditary hemorrhagic telangiectasia, and capillary malformation-arteriovenous malformation syndrome (related to the RASA1 mutation). The treatment of pediatric CNS vascular malformations has greatly benefited from advances in endovascular therapy, including technical advances in adult interventional neuroradiology. Dramatic advances in therapy are expected to stem from increased understanding of the genetics and vascular biology that underlie pediatric CNS vascular malformations. (orig.)

Pediatric central nervous system vascular malformations

International Nuclear Information System (INIS)

Burch, Ezra A.; Orbach, Darren B.

2015-01-01

Pediatric central nervous system (CNS) vascular anomalies include lesions found only in the pediatric population and also the full gamut of vascular lesions found in adults. Pediatric-specific lesions discussed here include infantile hemangioma, vein of Galen malformation and dural sinus malformation. Some CNS vascular lesions that occur in adults, such as arteriovenous malformation, have somewhat distinct manifestations in children, and those are also discussed. Additionally, children with CNS vascular malformations often have associated broader vascular conditions, e.g., PHACES (posterior fossa anomalies, hemangioma, arterial anomalies, cardiac anomalies, eye anomalies and sternal anomalies), hereditary hemorrhagic telangiectasia, and capillary malformation-arteriovenous malformation syndrome (related to the RASA1 mutation). The treatment of pediatric CNS vascular malformations has greatly benefited from advances in endovascular therapy, including technical advances in adult interventional neuroradiology. Dramatic advances in therapy are expected to stem from increased understanding of the genetics and vascular biology that underlie pediatric CNS vascular malformations. (orig.)

Oestrogen directly inhibits the cardiovascular L-type Ca2+ channel Cav1.2

International Nuclear Information System (INIS)

Ullrich, Nina D.; Koschak, Alexandra; MacLeod, Kenneth T.

2007-01-01

Oestrogen can modify the contractile function of vascular smooth muscle and cardiomyocytes. The negative inotropic actions of oestrogen on the heart and coronary vasculature appear to be mediated by L-type Ca 2+ channel (Ca v 1.2) inhibition, but the underlying mechanisms remain elusive. We tested the hypothesis that oestrogen directly inhibits the cardiovascular L-type Ca 2+ current, I CaL . The effect of oestrogen on I CaL was measured in Ca v 1.2-transfected HEK-293 cells using the whole-cell patch-clamp technique. The current revealed typical activation and inactivation profiles of nifedipine- and cadmium-sensitive I CaL . Oestrogen (50 μM) rapidly reduced I CaL by 50% and shifted voltage-dependent activation and availability to more negative potentials. Furthermore, oestrogen blocked the Ca 2+ channel in a rate-dependent way, exhibiting higher efficiency of block at higher stimulation frequencies. Our data suggest that oestrogen inhibits I CaL through direct interaction of the steroid with the channel protein

Dose-reduced 16-slice multidetector-row spiral computed tomography in children with bronchoscopically suspected vascular tracheal stenosis - initial results

International Nuclear Information System (INIS)

Honnef, D.; Wildberger, J.E.; Das, M.; Hohl, C.; Mahnken, A.; Guenther, R.W.; Staatz, G.; Schnoering, H.; Vazquez-Jimenez, J.

2006-01-01

Purpose: To evaluate the diagnostic accuracy of contrast-enhanced dose-reduced 16-slice multidetector-row CT (MDCT) in newborns and infants with fiberoptic bronchoscopically suspected vascular-induced tracheal stenosis. Materials and Methods: 12 children (4 days to 3 years, 1.2-13.5 kg body weight) were examined using i.v. contrast-enhanced 16-slice MDCT (SOMATOM Sensation 16, Forchheim, Germany) without breath-hold and under sedation (11/12). All MDCTs were performed with a dose reduction. The beam collimation was 16 x 0.75 mm, except in the case of one child. MPRs along the tracheal axis in the x-, y- and z-directions and volume-rendering-reconstructions (VRTs) were calculated based on a secondary raw data set in addition to conventional axial slices. 2 radiologists used a three-point grade scale to evaluate the image quality, motion, and contrast media artifacts as well as the usefulness of the 2D- and 3D-reconstructions for determining the diagnosis. Statistical analysis was performed on the basis of a Kappa test. Results: In all cases the cause of the fiberoptic bronchoscopically suspected tracheal stenosis was revealed: compression due to the brachiocephalic trunk (n=7), double aortic arch (n=2), lusorian artery (n=1), vascular compression of the left main bronchus (n=2). In 3 patients further thoracic anomalies, such as tracheobronchial (n=2), and vascular (n=2) and vertebral (n=1) anomalies were found. The attenuation in the anomalous vessels was 307±140 HU. The image noise was 9.8±1.9 HU. The mean dose reduction was 82.7±3.2% compared to a standard adult thoracic CT. All examinations were rated as diagnostically good (median 1, range 1, k=1). 3D images did not show any stair artifacts (median 2, range 1-2, k=1). The image noise was minor to moderate and hardly any motion artifacts were seen (median 1, range 1-2, k=0.8). Contrast media artifacts were rated zero to minor (median 1.5, range 1-2, k=0.676). MPRs (median 1, range 1, k=1) and VRTs (median 1

Intraoperative digital angiography: Peripheral vascular applications

International Nuclear Information System (INIS)

Bell, K.; Reifsteck, J.E.; Binet, E.F.; Fleisher, H.J.

1986-01-01

Intraoperative digital angiography is the procedure of choice for the peripheral vascular surgeon who wishes to evaluate his results before terminating anesthesia. Two operating suites at the John L. McClellan Memorial Veterans Hospital are equipped with permanent ceiling-mounted Philips C-arm fluoroscopes and share an ADAC 4100 digital angiographic system. In the last 18 months, 40 peripheral vascular intraoperative digital angiographic procedures have been performed, in all but two cases using direct arterial puncture. In 65% of cases, the intraoperative study showed no significant abnormality. In 12.5%, minor abnormalities not requiring reoperation were seen. In 22.5% of cases, the intraoperative digital angiogram revealed a significant abnormality requiring immediate operative revision. None of the patients who underwent reoperation experienced postoperative sequelae. Intraoperative digital angiography is useful in identifying complications of peripheral vascular operations

Injuries to the vascular endothelium: vascular wall and endothelial dysfunction.

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Fisher, Mark

2008-01-01

Vascular endothelial injury has multiple elements, and this article focuses on ischemia-related processes that have particular relevance to ischemic stroke. Distinctions between necrotic and apoptotic cell death provide a basic science context in which to better understand the significance of classical core and penumbra concepts of acute stroke, with apoptotic processes particularly prominent in the penumbra. The mitochondria are understood to serve as a reservoir of proteins that mediate apoptosis. Oxidative stress pathways generating reactive oxygen species (ROS) are prominent in endothelial injury, both ischemic and nonischemic, with prominent roles of enzyme- and nonenzymemediated pathways; mitochondria once again have a critical role, particularly in the nonenzymatic pathways generating ROS. Inflammation also contributes to vascular endothelial injury, and endothelial cells have the capacity to rapidly increase expression of inflammatory mediators following ischemic challenge; this leads to enhanced leukocyte-endothelial interactions mediated by selectins and adhesion molecules. Preconditioning consists of a minor version of an injurious event, which in turn may protect vascular endothelium from injury following a more substantial event. Presence of the blood-brain barrier creates unique responses to endothelial injury, with permeability changes due to impairment of endothelial-matrix interactions compounding altered vasomotor tone and tissue perfusion mediated by nitric oxide. Pharmacological protection against vascular endothelial injury can be provided by several of the phosphodiesterases (cilostazol and dipyridamole), along with statins. Optimal clinical responses for protection of brain vascular endothelium may use preconditioning as a model, and will likely require combined protection against apoptosis, ROS, and inflammation.

Fabrication and characterization of gels with integrated channels using 3D printing with microfluidic nozzle for tissue engineering applications.

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Attalla, R; Ling, C; Selvaganapathy, P

2016-02-01

The lack of a simple and effective method to integrate vascular network with engineered scaffolds and tissue constructs remains one of the biggest challenges in true 3D tissue engineering. Here, we detail the use of a commercially available, low-cost, open-source 3D printer modified with a microfluidic print-head in order to develop a method for the generation of instantly perfusable vascular network integrated with gel scaffolds seeded with cells. The print-head features an integrated coaxial nozzle that allows the fabrication of hollow, calcium-polymerized alginate tubes that can be easily patterned using 3D printing techniques. The diameter of the hollow channel can be precisely controlled and varied between 500 μm - 2 mm by changing applied flow rates or print-head speed. These channels are integrated into gel layers with a thickness of 800 μm - 2.5 mm. The structural rigidity of these constructs allows the fabrication of multi-layered structures without causing the collapse of hollow channels in lower layers. The 3D printing method was fully characterized at a range of operating speeds (0-40 m/min) and corresponding flow rates (1-30 mL/min) were identified to produce precise definition. This microfluidic design also allows the incorporation of a wide range of scaffold materials as well as biological constituents such as cells, growth factors, and ECM material. Media perfusion of the channels causes a significant viability increase in the bulk of cell-laden structures over the long-term. With this setup, gel constructs with embedded arrays of hollow channels can be created and used as a potential substitute for blood vessel networks.

The Extended-Window Channel Estimator for Iterative Channel-and-Symbol Estimation

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Barry John R

2005-01-01

Full Text Available The application of the expectation-maximization (EM algorithm to channel estimation results in a well-known iterative channel-and-symbol estimator (ICSE. The EM-ICSE iterates between a symbol estimator based on the forward-backward recursion (BCJR equalizer and a channel estimator, and may provide approximate maximum-likelihood blind or semiblind channel estimates. Nevertheless, the EM-ICSE has high complexity, and it is prone to misconvergence. In this paper, we propose the extended-window (EW estimator, a novel channel estimator for ICSE that can be used with any soft-output symbol estimator. Therefore, the symbol estimator may be chosen according to performance or complexity specifications. We show that the EW-ICSE, an ICSE that uses the EW estimator and the BCJR equalizer, is less complex and less susceptible to misconvergence than the EM-ICSE. Simulation results reveal that the EW-ICSE may converge faster than the EM-ICSE.

Vascular Risk Factors and Clinical Progression in Spinocerebellar Ataxias

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Raymond Y. Lo

2015-02-01

Full Text Available Background: The contributions of vascular risk factors to spinocerebellar ataxia (SCA are not known.Methods: We studied 319 participants with SCA 1, 2, 3, and 6 and repeatedly measured clinical severity using the Scale for Assessment and Rating of Ataxia (SARA for 2 years. Vascular risk factors were summarized by CHA2DS2-VASc scores as the vascular risk factor index. We employed regression models to study the effects of vascular risk factors on ataxia onset and progression after adjusting for age, sex, and pathological CAG repeats. Our secondary analyses took hyperlipidemia into account.Results: Nearly 60% of SCA participants were at low vascular risks with CHA2DS2-VASc = 0, and 31% scored 2 or greater. Higher CHA2DS2-VASc scores were not associated with either earlier onset or faster progression of ataxia. These findings were not altered after accounting for hyperlipidemia. Discussion: Vascular risks are not common in SCAs and are not associated with earlier onset or faster ataxia progression.

Clinical applications of robotic technology in vascular and endovascular surgery.

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Antoniou, George A; Riga, Celia V; Mayer, Erik K; Cheshire, Nicholas J W; Bicknell, Colin D

2011-02-01

Emerging robotic technologies are increasingly being used by surgical disciplines to facilitate and improve performance of minimally invasive surgery. Robot-assisted intervention has recently been introduced into the field of vascular surgery to potentially enhance laparoscopic vascular and endovascular capabilities. The objective of this study was to review the current status of clinical robotic applications in vascular surgery. A systematic literature search was performed in order to identify all published clinical studies related to robotic implementation in vascular intervention. Web-based search engines were searched using the keywords "surgical robotics," "robotic surgery," "robotics," "computer assisted surgery," and "vascular surgery" or "endovascular" for articles published between January 1990 and November 2009. An evaluation and critical overview of these studies is reported. In addition, an analysis and discussion of supporting evidence for robotic computer-enhanced telemanipulation systems in relation to their applications in laparoscopic vascular and endovascular surgery was undertaken. Seventeen articles reporting on clinical applications of robotics in laparoscopic vascular and endovascular surgery were detected. They were either case reports or retrospective patient series and prospective studies reporting laparoscopic vascular and endovascular treatments for patients using robotic technology. Minimal comparative clinical evidence to evaluate the advantages of robot-assisted vascular procedures was identified. Robot-assisted laparoscopic aortic procedures have been reported by several studies with satisfactory results. Furthermore, the use of robotic technology as a sole modality for abdominal aortic aneurysm repair and expansion of its applications to splenic and renal artery aneurysm reconstruction have been described. Robotically steerable endovascular catheter systems have potential advantages over conventional catheterization systems

Relational databases for rare disease study: application to vascular anomalies.

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Perkins, Jonathan A; Coltrera, Marc D

2008-01-01

To design a relational database integrating clinical and basic science data needed for multidisciplinary treatment and research in the field of vascular anomalies. Based on data points agreed on by the American Society of Pediatric Otolaryngology (ASPO) Vascular Anomalies Task Force. The database design enables sharing of data subsets in a Health Insurance Portability and Accountability Act (HIPAA)-compliant manner for multisite collaborative trials. Vascular anomalies pose diagnostic and therapeutic challenges. Our understanding of these lesions and treatment improvement is limited by nonstandard terminology, severity assessment, and measures of treatment efficacy. The rarity of these lesions places a premium on coordinated studies among multiple participant sites. The relational database design is conceptually centered on subjects having 1 or more lesions. Each anomaly can be tracked individually along with their treatment outcomes. This design allows for differentiation between treatment responses and untreated lesions' natural course. The relational database design eliminates data entry redundancy and results in extremely flexible search and data export functionality. Vascular anomaly programs in the United States. A relational database correlating clinical findings and photographic, radiologic, histologic, and treatment data for vascular anomalies was created for stand-alone and multiuser networked systems. Proof of concept for independent site data gathering and HIPAA-compliant sharing of data subsets was demonstrated. The collaborative effort by the ASPO Vascular Anomalies Task Force to create the database helped define a common vascular anomaly data set. The resulting relational database software is a powerful tool to further the study of vascular anomalies and the development of evidence-based treatment innovation.

Our vascular surgery experiences in Syrian civil war

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İyad Fansa

2014-12-01

Full Text Available Objective: Due to the ongoing civil war in Syria, numerous vascular injured patients are admitted to our hospital with gunshot wounds. In this study, patients who admitted our hospital, diagnosed with vascular trauma due to gunshot were evaluated with the respect of injury site, additional injuries, surgical interventions and outcomes. Methods: The study included 58 patients wounded in Syrian war and admitted to our hospital between 01.01.2012 and 01.09.2014. Results= There were 5.1% (n=3 female and 94.9% (n=55 male patients. Age range is 5-75 years and the average of age was identified as 28.61. In 12.1% (n=7 of patients with extensive tissue defects of the muscle-nerve-bone injury has been identified, despite the vascular interventions in these patients, 8.6% (n=5 of patients, the limb has been amputated. Totally 15.5% (n=9 of 58 operated patients died. Two patients died because of major vascular injury with intra-abdominal organ injuries. In one patient; infection induced sepsis and multi organ failure was detected. Six patients were lost due to hypovolemic shock as a result of late arriving. Conclusion: In patients admitted with gunshot vascular injury arrival time, the presence of additional injuries and the location of injury affect mortality rates.

Initial Clinical Experience Using the Amplatzer Vascular Plug

International Nuclear Information System (INIS)

Tuite, David J.; Kessel, David O.; Nicholson, Anthony A.; Patel, Jai V.; McPherson, Simon J.; Shaw, David R.

2007-01-01

Background and purpose. The Amplatzer Vascular Plug (AVP) is a self-expanding nitinol wire mesh vascular embolization device derived from the Amplatz septal occluder. We assessed the results of vascular embolization obtained using the AVP. Methods. A retrospective review was carried out of 23 consecutive cases of vascular embolization using the AVP in a variety of different clinical settings. The AVP was chosen to have a diameter approximately 30-50% greater than the target vessel. The device was delivered via an appropriately sized guide catheter and was released when satisfactorily positioned. Additional embolic agents were used in some cases. Results. All target vessels were successfully occluded with no device malpositioning or malfunction. In 14 (61%) patients the AVP was the sole embolic material. In the remaining patients additional agents were used, particularly in preoperative embolization of highly vascular renal tumors. The AVP does not cause instantaneous thrombosis and in high-flow situations thrombosis typically takes up to 15 min. Conclusion. The AVP is a safe, effective embolization device that provides a useful adjunct to the therapeutic armamentarium. It is particularly suited to the treatment of short high-flow vessels where coil migration and catheter dislodgment might occur. In the majority of cases no additional embolic agents are necessary but it may take up to 15 min for complete thrombosis to occur

Ion channeling

International Nuclear Information System (INIS)

Erramli, H.; Blondiaux, G.

1994-01-01

Channeling phenomenon was predicted, many years ago, by stark. The first channeling experiments were performed in 1963 by Davies and his coworkers. Parallely Robinson and Oen have investigated this process by simulating trajectories of ions in monocrystals. This technique has been combined with many methods like Rutherford Backscattering Spectrometry (R.B.S.), Particles Induced X-rays Emission (P.I.X.E) and online Nuclear Reaction (N.R.A.) to localize trace elements in the crystal or to determine crystalline quality. To use channeling for material characterization we need data about the stopping power of the incident particle in the channeled direction. The ratios of channeled to random stopping powers of silicon for irradiation in the direction have been investigated and compared to the available theoretical results. We describe few applications of ion channeling in the field of materials characterization. Special attention is given to ion channeling combined with Charged Particle Activation Analysis (C.P.A.A.) for studying the behaviour of oxygen atoms in Czochralski silicon lattices under the influence of internal gettering and in different gaseous atmospheres. Association between ion channeling and C.P.A.A was also utilised for studying the influence of the growing conditions on concentration and position of carbon atoms at trace levels in the MOVPE Ga sub (1-x) Al sub x lattice. 6 figs., 1 tab., 32 refs. (author)

Channel identification machines.

Science.gov (United States)

Lazar, Aurel A; Slutskiy, Yevgeniy B

2012-01-01

We present a formal methodology for identifying a channel in a system consisting of a communication channel in cascade with an asynchronous sampler. The channel is modeled as a multidimensional filter, while models of asynchronous samplers are taken from neuroscience and communications and include integrate-and-fire neurons, asynchronous sigma/delta modulators and general oscillators in cascade with zero-crossing detectors. We devise channel identification algorithms that recover a projection of the filter(s) onto a space of input signals loss-free for both scalar and vector-valued test signals. The test signals are modeled as elements of a reproducing kernel Hilbert space (RKHS) with a Dirichlet kernel. Under appropriate limiting conditions on the bandwidth and the order of the test signal space, the filter projection converges to the impulse response of the filter. We show that our results hold for a wide class of RKHSs, including the space of finite-energy bandlimited signals. We also extend our channel identification results to noisy circuits.

Channel Identification Machines

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Aurel A. Lazar

2012-01-01

Full Text Available We present a formal methodology for identifying a channel in a system consisting of a communication channel in cascade with an asynchronous sampler. The channel is modeled as a multidimensional filter, while models of asynchronous samplers are taken from neuroscience and communications and include integrate-and-fire neurons, asynchronous sigma/delta modulators and general oscillators in cascade with zero-crossing detectors. We devise channel identification algorithms that recover a projection of the filter(s onto a space of input signals loss-free for both scalar and vector-valued test signals. The test signals are modeled as elements of a reproducing kernel Hilbert space (RKHS with a Dirichlet kernel. Under appropriate limiting conditions on the bandwidth and the order of the test signal space, the filter projection converges to the impulse response of the filter. We show that our results hold for a wide class of RKHSs, including the space of finite-energy bandlimited signals. We also extend our channel identification results to noisy circuits.

Vascular malformations in pediatrics

International Nuclear Information System (INIS)

Reith, W.; Shamdeen, M.G.

2003-01-01

Vascular malformations are the cause of nearly all non-traumatic intracranial hemorrhage in children beyond the neonatal stage. Therefore, any child presenting with spontaneous intracranial hemorrhage should be evaluated for child abuse and for vascular malformations. Intracerebral malformations of the cerebral vasculature include vein of Galen malformations, arteriovenous malformation (AVM), cavernomas, dural arteriovenous fistulas, venous anomalies (DVA), and capillary teleangiectasies. Although a few familial vascular malformation have been reported, the majority are sporadic. Clinical symptoms, diagnostic and therapeutic options are discussed. (orig.) [de

SGK3 Sensitivity of Voltage Gated K+ Channel Kv1.5 (KCNA5

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Musaab Ahmed

2016-01-01

Full Text Available Background: The serum & glucocorticoid inducible kinase isoform SGK3 is a powerful regulator of several transporters, ion channels and the Na+/K+ ATPase. Targets of SGK3 include the ubiquitin ligase Nedd4-2, which is in turn a known regulator of the voltage gated K+ channel Kv1.5 (KCNA5. The present study thus explored whether SGK3 modifies the activity of the voltage gated K+ channel KCNA5, which participates in the regulation of diverse functions including atrial cardiac action potential, activity of vascular smooth muscle cells, insulin release and tumour cell proliferation. Methods: cRNA encoding KCNA5 was injected into Xenopus oocytes with and without additional injection of cRNA encoding wild-type SGK3, constitutively active S419DSGK3, inactive K191NSGK3 and/or wild type Nedd4-2. Voltage gated K+ channel activity was quantified utilizing dual electrode voltage clamp. Results: Voltage gated current in KCNA5 expressing Xenopus oocytes was significantly enhanced by wild-type SGK3 and S419DSGK3, but not by K191NSGK3. SGK3 was effective in the presence of ouabain (1 mM and thus did not require Na+/K+ ATPase activity. Coexpression of Nedd4-2 decreased the voltage gated current in KCNA5 expressing Xenopus oocytes, an effect largely reversed by additional coexpression of SGK3. Conclusion: SGK3 is a positive regulator of KCNA5, which is at least partially effective by abrogating the effect of Nedd4-2.

Functional transient receptor potential vanilloid 1 and transient receptor potential vanilloid 4 channels along different segments of the renal vasculature

DEFF Research Database (Denmark)

Chen, L; Kaßmann, M; Sendeski, M

2015-01-01

with functional TRPV1 having a narrow, discrete distribution in the resistance vasculature and TRPV4 having more universal, widespread distribution along different vascular segments. We suggest that TRPV1/4 channels are potent therapeutic targets for site-specific vasodilation in the kidney.......AIM: Transient receptor potential vanilloid 1 (TRPV1) and vanilloid 4 (TRPV4) cation channels have been recently identified to promote endothelium-dependent relaxation of mouse mesenteric arteries. However, the role of TRPV1 and TRPV4 in the renal vasculature is largely unknown. We hypothesized...... that TRPV1/4 plays a role in endothelium-dependent vasodilation of renal blood vessels. METHODS: We studied the distribution of functional TRPV1/4 along different segments of the renal vasculature. Mesenteric arteries were studied as control vessels. RESULTS: The TRPV1 agonist capsaicin relaxed mouse...

History of Bioelectrical Study and the Electrophysiology of the Primo Vascular System

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Sang Hyun Park

2013-01-01

Full Text Available Background. Primo vascular system is a new anatomical structure whose research results have reported the possibility of a new circulatory system similar to the blood vascular system and cells. Electrophysiology, which measures and analyzes bioelectrical signals tissues and cells, is an important research area for investigating the function of tissues and cells. The bioelectrical study of the primo vascular system has been reported by using modern techniques since the early 1960s by Bonghan Kim. This paper reviews the research result of the electrophysiological study of the primo vascular system for the discussion of the circulatory function. We hope it would help to study the electrophysiology of the primo vascular system for researchers. This paper will use the following exchangeable expressions: Kyungrak system = Bonghan system = Bonghan circulatory system = primo vascular system = primo system; Bonghan corpuscle = primo node; Bonghan duct = primo vessel. We think that objective descriptions of reviewed papers are more important than unified expressions when citing the papers. That said, this paper will unify the expressions of the primo vascular system.

Contemporary vascular smartphone medical applications.

Science.gov (United States)

Carter, Thomas; O'Neill, Stephen; Johns, Neil; Brady, Richard R W

2013-08-01

Use of smartphones and medical mHealth applications (apps) within the clinical environment provides a potential means for delivering elements of vascular care. This article reviews the contemporary availability of apps specifically themed to major vascular diseases and the opportunities and concerns regarding their integration into practice. Smartphone apps relating to major vascular diseases were identified from the app stores for the 6 most popular smartphone platforms, including iPhone, Android, Blackberry, Nokia, Windows, and Samsung. Search terms included peripheral artery (arterial) disease, varicose veins, aortic aneurysm, carotid artery disease, amputation, ulcers, hyperhydrosis, thoracic outlet syndrome, vascular malformation, and lymphatic disorders. Forty-nine vascular-themed apps were identified. Sixteen (33%) were free of charge. Fifteen apps (31%) had customer satisfaction ratings, but only 3 (6%) had greater than 100. Only 13 apps (27%) had documented medical professional involvement in their design or content. The integration of apps into the delivery of care has the potential to benefit vascular health care workers and patients. However, high-quality apps designed by clinicians with vascular expertise are currently lacking and represent an area of concern in the mHealth market. Improvement in the quality and reliability of these apps will require the development of robust regulation. Copyright © 2013 Elsevier Inc. All rights reserved.

The roles of KCa, KATP, and KV channels in regulating cutaneous vasodilation and sweating during exercise in the heat.

Science.gov (United States)

Louie, Jeffrey C; Fujii, Naoto; Meade, Robert D; McNeely, Brendan D; Kenny, Glen P

2017-05-01

We recently showed the varying roles of Ca 2+ -activated (K Ca ), ATP-sensitive (K ATP ), and voltage-gated (K V ) K + channels in regulating cholinergic cutaneous vasodilation and sweating in normothermic conditions. However, it is unclear whether the respective contributions of these K + channels remain intact during dynamic exercise in the heat. Eleven young (23 ± 4 yr) men completed a 30-min exercise bout at a fixed rate of metabolic heat production (400 W) followed by a 40-min recovery period in the heat (35°C, 20% relative humidity). Cutaneous vascular conductance (CVC) and local sweat rate were assessed at four forearm skin sites perfused via intradermal microdialysis with: 1 ) lactated Ringer solution (control); 2 ) 50 mM tetraethylammonium (nonspecific K Ca channel blocker); 3 ) 5 mM glybenclamide (selective K ATP channel blocker); or 4 ) 10 mM 4-aminopyridine (nonspecific K V channel blocker). Responses were compared at baseline and at 10-min intervals during and following exercise. K Ca channel inhibition resulted in greater CVC versus control at end exercise ( P = 0.04) and 10 and 20 min into recovery (both P exercise (all P ≤ 0.04), and 10 min into recovery ( P = 0.02). No differences in CVC were observed with K V channel inhibition during baseline ( P = 0.15), exercise (all P ≥ 0.06), or recovery (all P ≥ 0.14). With the exception of K V channel inhibition augmenting sweating during baseline ( P = 0.04), responses were similar to control with all K + channel blockers during each time period (all P ≥ 0.07). We demonstrated that K Ca and K ATP channels contribute to the regulation of cutaneous vasodilation during rest and/or exercise and recovery in the heat. Copyright © 2017 the American Physiological Society.

Pancreatic transplantation: Radiologic evaluation of vascular complications

International Nuclear Information System (INIS)

Snider, J.F.; Hunter, D.W.; Kuni, C.C.; Castaneda-Zuniga, W.R.; Letourneau, J.G.

1991-01-01

Transplantation of the pancreas is an increasingly common therapeutic option for preventing or delaying complications of type I diabetes mellitus. The authors studied the relative roles of various radiologic examinations in diagnosing vascular complications in these grafts including arterial and venous thrombosis, stenosis, and anastomotic leak (the most common vascular factors that necessitate pancreatectomy of the transplant), as defined with pathologic or arteriographic data. The results of 78 scintigraphic flow studies, 40 abdominal and pelvic computed tomographic (CT) scans, 27 sonograms, and eight color Doppler studies were evaluated in 52 patients who received a total of 27 cadaveric and 26 living-donor grafts over a 12-year period. These results were correlated with the data from 45 gross and microscopic pathologic studies and 37 arteriograms to determine their relative value in enabling detection of graft thrombosis and other vascular complications. Scintigraphy, CT, sonography, and color Doppler were all sensitive in detection of generalized graft abnormalities but lacked specificity in defining the underlying etiologic factors

Pancreatic transplantation: Radiologic evaluation of vascular complications

Energy Technology Data Exchange (ETDEWEB)

Snider, J.F.; Hunter, D.W.; Kuni, C.C.; Castaneda-Zuniga, W.R.; Letourneau, J.G. (Univ. of Minnesota Hospital and Clinic, Minneapolis (USA))

1991-03-01

Transplantation of the pancreas is an increasingly common therapeutic option for preventing or delaying complications of type I diabetes mellitus. The authors studied the relative roles of various radiologic examinations in diagnosing vascular complications in these grafts including arterial and venous thrombosis, stenosis, and anastomotic leak (the most common vascular factors that necessitate pancreatectomy of the transplant), as defined with pathologic or arteriographic data. The results of 78 scintigraphic flow studies, 40 abdominal and pelvic computed tomographic (CT) scans, 27 sonograms, and eight color Doppler studies were evaluated in 52 patients who received a total of 27 cadaveric and 26 living-donor grafts over a 12-year period. These results were correlated with the data from 45 gross and microscopic pathologic studies and 37 arteriograms to determine their relative value in enabling detection of graft thrombosis and other vascular complications. Scintigraphy, CT, sonography, and color Doppler were all sensitive in detection of generalized graft abnormalities but lacked specificity in defining the underlying etiologic factors.

Expression of Vascular Endothelial Growth Factor Receptors in Benign Vascular Lesions of the Orbit: A Case Series.

Science.gov (United States)

Atchison, Elizabeth A; Garrity, James A; Castillo, Francisco; Engman, Steven J; Couch, Steven M; Salomão, Diva R

2016-01-01

Vascular lesions of the orbit, although not malignant, can cause morbidity because of their location near critical structures in the orbit. For the same reason, they can be challenging to remove surgically. Anti-vascular endothelial growth factor (VEGF) drugs are increasingly being used to treat diseases with prominent angiogenesis. Our study aimed to determine to what extent VEGF receptors and their subtypes are expressed on selected vascular lesions of the orbit. Retrospective case series of all orbital vascular lesions removed by one of the authors (JAG) at the Mayo Clinic. A total of 52 patients who underwent removal of vascular orbital lesions. The pathology specimens from the patients were retrieved, their pathologic diagnosis was confirmed, demographic and clinical information were gathered, and sections from vascular tumors were stained with vascular endothelial growth factor receptor (VEGFR), vascular endothelial growth factor receptor type 1 (VEGFR1), vascular endothelial growth factor receptor type 2 (VEGFR2), and vascular endothelial growth factor receptor type 3 (VEGFR3). The existence and pattern of staining with VEGF and its subtypes on these lesions. There were 28 specimens of venous malformations, 4 capillary hemangiomas, 7 lymphatic malformations, and 6 lymphaticovenous malformations. All samples stained with VEGF, 55% stained with VEGFR1, 98% stained with VEGFR2, and 96% stained with VEGFR3. Most (94%) of the VEGFR2 staining was diffuse. Most orbital vascular lesions express VEGF receptors, which may suggest a future target for nonsurgical treatment. Copyright © 2016 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.

Vascular Neurology Nurse Practitioner Provision of Telemedicine Consultations

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Bart M. Demaerschalk

2010-01-01

Full Text Available Objective. The objective was to define and evaluate a role for the Vascular Neurology-Nurse Practitioner (VN-NP in the delivery of telemedicine consultations in partnership with a vascular neurologist. Methods. Prospective stroke alert patients at participating hospitals underwent a two-way audio video telemedicine consultation with a VN-NP at a remotely located stroke center in partnership with a vascular neurologist. Demographic information, National Institutes of Health Stroke Scale (NIHSS scores, diagnoses, CT contraindications to thrombolysis, thrombolysis eligibility, and time interval data were collected. The inter-rater agreement between VN-NP and vascular neurologist assessments was calculated. Results. Ten patients were evaluated. Four were determined to have ischemic stroke, one had a transient ischemic attack, two had intracerebral hemorrhages, and three were stroke mimics. Overall, three patients received thrombolysis. The inter-rater agreement between VN-NP and vascular neurologist assessments were excellent, ranging from 0.9 to 1.0. The duration of VN-NP consultation was 53.2±9.0 minutes, which included the vascular neurologist supervisory evaluation time of 12.0±9.6 minutes. Conclusion. This study illustrated that a stroke center VN-NP, in partnership with a vascular neurologist, could deliver timely telemedicine consultations, accurate diagnoses, and correct treatments in acute stroke patients who presented to remotely located rural emergency departments within a hub and spoke network. VN-NPs may fulfill the role of a telestroke provider.

Deficiency of superoxide dismutase promotes cerebral vascular hypertrophy and vascular dysfunction in hyperhomocysteinemia.

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Sanjana Dayal

Full Text Available There is an emerging consensus that hyperhomocysteinemia is an independent risk factor for cerebral vascular disease and that homocysteine-lowering therapy protects from ischemic stroke. However, the mechanisms by which hyperhomocysteinemia produces abnormalities of cerebral vascular structure and function remain largely undefined. Our objective in this study was to define the mechanistic role of superoxide in hyperhomocysteinemia-induced cerebral vascular dysfunction and hypertrophy. Unlike previous studies, our experimental design included a genetic approach to alter superoxide levels by using superoxide dismutase 1 (SOD1-deficient mice fed a high methionine/low folate diet to produce hyperhomocysteinemia. In wild-type mice, the hyperhomocysteinemic diet caused elevated superoxide levels and impaired responses to endothelium-dependent vasodilators in cerebral arterioles, and SOD1 deficiency compounded the severity of these effects. The cross-sectional area of the pial arteriolar wall was markedly increased in mice with SOD1 deficiency, and the hyperhomocysteinemic diet sensitized SOD1-deficient mice to this hypertrophic effect. Analysis of individual components of the vascular wall demonstrated a significant increase in the content of smooth muscle and elastin. We conclude that superoxide is a key driver of both cerebral vascular hypertrophy and vasomotor dysfunction in this model of dietary hyperhomocysteinemia. These findings provide insight into the mechanisms by which hyperhomocysteinemia promotes cerebral vascular disease and ischemic stroke.

Vascular training and endovascular practice in Europe

DEFF Research Database (Denmark)

Liapis, C.D.; Avgerinos, E.D.; Sillesen, H.

2009-01-01

specialties was distributed to a VS educator within 14 European countries. European Vascular and Endovascular Monitor (EVEM) data also were processed to correlate endovascular practice with training models. RESULTS: Fourteen questionnaires were gathered. Vascular training in Europe appears in 3 models: 1....... Mono-specialty (independence): 7 countries, 2. Subspecialty: 5 countries, 3. An existing specialty within general surgery: 2 countries. Independent compared to non-independent certification shortens overall training length (5.9 vs 7.9 years, p=0.006), while increasing overall training devoted......% respectively. Countries with independent vascular certification, despite their lower average endovascular index (procedures per 100,000 population), reported a higher growth rate of aortic endovascular procedures (VS independent 132% vs VS non-independent 87%), within a four-year period (2003-2007). Peripheral...

[Synopsis about the hypothesis of "information channel" of channel-collateral system].

Science.gov (United States)

Chang, Xi-Lang

2008-10-01

The author of the present paper founded a theorem about the "incompleteness of single channel structure" (nerve, blood vessel, lymphatic, interspace, aperture, etc.) through quantitative and qualitative analysis about the economic information channel in the human body, which eliminates the probability of single channel structure in the information channel of channel (meridian)-collateral system. After comprehensive analysis on the current researches, the author puts forward a neodoxy, i.e., the body "information channel" structure of the channel-collateral system, mainly follows the distribution regularity of systemic statistics, and is not a single specific entity; various layers of the information channel in the main stems of the channel-collaterals are composed of optimized structure tissues. Hence, the structure of this information channel of channel-collateral system is an overall-optimized, sequential and compatible systemic structure. From this neodoxy, the author brings forward a working principle of channel-collaterals, which is supported theoretically by bio-auxology. The longitudinal distribution of the main stems of meridian-collaterals is considered to result from that in the process of the animal evolution, in the animals moving forward, the microscopic complicated movement of intracorporeal information and energy molecules is related to the forward macroscopic and non-uniform movement of organism in trans-measure. Its impulse and kinetic momentum forms a main vector in the longitudinal direction of the body (the direction of the main stem of channel-collaterals). In order to adapt to and utilize natural regularities, the main stems of the channel-collaterals gradually differentiate and evolve in the living organism, forming a whole system. The "hypothesis of biological origin of channel-collateral system" and "that of information channel of the channel-collaterals in the body" constitute a relatively complete theoretical system framework.

Nilai Rerata Vascular Pedicle Width, Vascular Pedicle-Cardiac Ratio Vascular Pedicle-Thoracic Ratio Orang Dewasa Normal Indonesia Studi di RS dr. Cipto Mangunkusomo

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Rommy Zunera

2016-03-01

Full Text Available Vascular pedicle width (VPW adalah jarak tepi luar vena kava superior ke tepi luar arteri subklavia kiri. Pemeriksaan VPW di foto toraks bersifat non-invasif, cepat dan mudah untuk memprediksi hipervolemia.Penelitian ini bertujuan untuk mengetahui rerata nilai VPW orang dewasa normal Indonesia. VPW diukurdengan dua metode: pertama pengukuran VPW tunggal yang akurasinya terbatas di foto toraks digital karenarelatif tidak dipengaruhi faktor magnifikasi. Metode kedua untuk foto toraks nondigital yaitu pengukuranrasio:vascular pedicle-cardiac ratio (VPCR dan vascular pedicle-thoracic ratio (VPTR. Pengukuran serupadilakukan terhadap  topogram CT scan toraks AP terlentang dan CT scan toraks lalu dibandingkan akurasipengukuran di topogram dengan CT scan  toraks sebagai standar baku. Sampel terdiri atas 104 foto toraksPA subyek normal dan 103 CT scan  toraks subyek terpilih. Pada pemeriksaan toraks PA didapatkan rerata VPW 48,0±5,5mm, rerata VPCR 40,3±4,6%, dan rerata VPTR 17,2±1,7%. Pada pemeriksaan topogram CTscan didapatkan rerata VPW 50,3±6,2mm, rerata VPTR 45±5,1%, dan rerata VPTR 19,8±2,5%. Rerata VPWpada CT scan toraks 50,4±6,1mm. Pengukuran di foto toraks AP 10% lebih besar dibandingkan pada fototoraks PA dan pengukuranVPW di foto toraks terbukti memiliki akurasi  tinggi. Kata kunci: fototoraks, vascular pedicle width, vascular pedicle-cardiac ratio, vascular pedicle-thoracic ratio, hipervolemia.   The Mean Value of Vascular Pedicle Width, Vascular Pedicle-Cardiac Ratio,Vascular Pedicle-Thoracic Ratio of Normal Indonesian Adult Study In dr. Cipto Mangunkusomo Hospital Abstract Vascular pedicle width (VPW is the distance, from a perpendicular line at the takeoff point of the left subclavian artery off the aorta to the point at which the superior vena cava. Measurement of VPW on chestx-ray is relatively non-invasive, fast and easy technique as  hypervolemia predictor. The purpose of thisstudy is to know the mean VPW value of normal

Fine Channel Networks

Science.gov (United States)

1997-01-01

A color image of fine channel networks on Mars; north toward top. The scene shows heavily cratered highlands dissected by dendritic open channel networks that dissect steep slopes of impact crater walls. This image is a composite of Viking high-resolution images in black and white and low-resolution images in color. The image extends from latitude 9 degrees S. to 5 degrees S. and from longitude 312 degrees to 320 degrees; Mercator projection. The dendritic pattern of the fine channels and their location on steep slopes leads to the interpretation that these are runoff channels. The restriction of these types of channels to ancient highland rocks suggests that these channels are old and date from a time on Mars when conditions existed for precipitation to actively erode rocks. After the channels reach a low plain, they appear to end. Termination may have resulted from burial by younger deposits or perhaps the flows percolated into the surface materials and continued underground.

Calcium dynamics in vascular smooth muscle

OpenAIRE

Amberg, Gregory C.; Navedo, Manuel F.

2013-01-01

Smooth muscle cells are ultimately responsible for determining vascular luminal diameter and blood flow. Dynamic changes in intracellular calcium are a critical mechanism regulating vascular smooth muscle contractility. Processes influencing intracellular calcium are therefore important regulators of vascular function with physiological and pathophysiological consequences. In this review we discuss the major dynamic calcium signals identified and characterized in vascular smooth muscle cells....

In situ replacement of infected vascular prosthesis with fresh arterial homograft: Early and long-term results in 18 patients

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Pejkić Siniša

2013-01-01

Full Text Available Introduction. Graft infection is rightly considered one of the severest complications of vascular reconstruction. Treatment is non­standardized and associated with high mortality and morbidity rates. The choice of therapeutic modality depends upon variety of factors. One increasingly used option is in situ replacement of the infected prosthesis with the arterial allograft. Objective. The aim of this prospective nonrandomized study was to evaluate the effectiveness and durability of fresh arterial allograft as in situ substitute for the infected vascular prosthesis. Methods. During period of 2002-2005, 18 patients with the synthetic vascular graft infection underwent partial or complete prosthesis removal and secondary in situ reconstruction using the fresh arterial allograft, preserved under hypothermic conditions in buffered saline solution with an addition of antibiotics. Results. In 14 male and 4 female patients, meanaged 62 years, 8 aortic and 10 peripheral arterial infected prostheses were partially or completely replaced with the allograft. Operative mortality was 27.8% and amputation rate was 22.2%. Systemic sepsis at initial presentation and highly virulent nature of causative microorganisms were identified as significant negative prognostic factors (χ² test, p<0.05. During the long­term follow­up (mean 47 months, allograft aneurysm developed in three patients, requiring allograft explantation, followed in two cases by tertiary prosthetic reconstruction. Conclusion. Substitution of the infected prosthesis with the arterial allograft could be successful if used selectively - for less virulent and localized infections of extracavitary grafts. Close follow­up is mandatory for timely diagnosis of late homograft lesions and its eventual replacement with more durable prosthetic material.

Evaluating Peripheral Vascular Injuries: Is Color Doppler Enough for Diagnosis?

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Mohd Lateef Wani

2014-03-01

Full Text Available Background:: Vascular injury poses a serious threat to limb and life. Thus, diagnosis should be made immediately with minimally invasive methods. Doppler is a good aid in diagnosis of vascular injury. Methods:: The present prospective study was conducted on 150 patients who presented with soft signs (the signs which are suggestive but not confirmatory of vascular injury. They were subjected to color Doppler examination before exploration. The patients with the features of vascular injury on color Doppler were subjected to exploration. On the other hand, those who had normal Doppler were subjected to CT- angiography. Then, the findings of the exploration were matched with those of color Doppler. The data were analyzed using the SPSS statistical software. Results:: Out of the 150 Doppler examinations, 110 (73.33% were reported as positive, while 40 were reported as negative for vascular injury. These were subjected to CT-angiography and seven of them had the features of vascular injury on CT-angiography. All the patients with positive Doppler or CT angiography findings were subjected to exploration. Doppler had a sensitivity of 94% and specificity of 82.5% in diagnosis of vascular injury using Binary classification test. Conclusions:: Color Doppler is an easily available, reliable, and handy method of diagnosing a vascular injury. It has a very high sensitivity and specificity in diagnosis of vascular injuries.

Bone Marrow Vascular Niche: Home for Hematopoietic Stem Cells

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Ningning He

2014-01-01

Full Text Available Though discovered later than osteoblastic niche, vascular niche has been regarded as an alternative indispensable niche operating regulation on hematopoietic stem cells (HSCs. As significant progresses gained on this type niche, it is gradually clear that the main work of vascular niche is undertaking to support hematopoiesis. However, compared to what have been defined in the mechanisms through which the osteoblastic niche regulates hematopoiesis, we know less in vascular niche. In this review, based on research data hitherto we will focus on component foundation and various functions of vascular niche that guarantee the normal hematopoiesis process within bone marrow microenvironments. And the possible pathways raised by various research results through which this environment undergoes its function will be discussed as well.

KV7 potassium channels

DEFF Research Database (Denmark)

Stott, Jennifer B; Jepps, Thomas Andrew; Greenwood, Iain A

2014-01-01

Potassium channels are key regulators of smooth muscle tone, with increases in activity resulting in hyperpolarisation of the cell membrane, which acts to oppose vasoconstriction. Several potassium channels exist within smooth muscle, but the KV7 family of voltage-gated potassium channels have been...

Open and endovascular aneurysm repair in the Society for Vascular Surgery Vascular Quality Initiative.

Science.gov (United States)

Spangler, Emily L; Beck, Adam W

2017-12-01

The Society for Vascular Surgery Vascular Quality Initiative is a patient safety organization and a collection of procedure-based registries that can be utilized for quality improvement initiatives and clinical outcomes research. The Vascular Quality Initiative consists of voluntary participation by centers to collect data prospectively on all consecutive cases within specific registries which physicians and centers elect to participate. The data capture extends from preoperative demographics and risk factors (including indications for operation), through the perioperative period, to outcomes data at up to 1-year of follow-up. Additionally, longer-term follow-up can be achieved by matching with Medicare claims data, providing long-term longitudinal follow-up for a majority of patients within the Vascular Quality Initiative registries. We present the unique characteristics of the Vascular Quality Initiative registries and highlight important insights gained specific to open and endovascular abdominal aortic aneurysm repair. Copyright © 2017 Elsevier Inc. All rights reserved.

In vitro model of vascularized bone: synergizing vascular development and osteogenesis.

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Cristina Correia

Full Text Available Tissue engineering provides unique opportunities for regenerating diseased or damaged tissues using cells obtained from tissue biopsies. Tissue engineered grafts can also be used as high fidelity models to probe cellular and molecular interactions underlying developmental processes. In this study, we co-cultured human umbilical vein endothelial cells (HUVECs and human mesenchymal stem cells (MSCs under various environmental conditions to elicit synergistic interactions leading to the colocalized development of capillary-like and bone-like tissues. Cells were encapsulated at the 1:1 ratio in fibrin gel to screen compositions of endothelial growth medium (EGM and osteogenic medium (OM. It was determined that, to form both tissues, co-cultures should first be supplied with EGM followed by a 1:1 cocktail of the two media types containing bone morphogenetic protein-2. Subsequent studies of HUVECs and MSCs cultured in decellularized, trabecular bone scaffolds for 6 weeks assessed the effects on tissue construct of both temporal variations in growth-factor availability and addition of fresh cells. The resulting grafts were implanted subcutaneously into nude mice to determine the phenotype stability and functionality of engineered vessels. Two important findings resulted from these studies: (i vascular development needs to be induced prior to osteogenesis, and (ii the addition of additional hMSCs at the osteogenic induction stage improves both tissue outcomes, as shown by increased bone volume fraction, osteoid deposition, close proximity of bone proteins to vascular networks, and anastomosis of vascular networks with the host vasculature. Interestingly, these observations compare well with what has been described for native development. We propose that our cultivation system can mimic various aspects of endothelial cell-osteogenic precursor interactions in vivo, and could find utility as a model for studies of heterotypic cellular interactions that

Vascular injuries after bear attacks: Incidence, surgical challenges and outcome.

Science.gov (United States)

Wani, Mohd Lateef; Ahangar, Abdul Gani; Lone, Gh Nabi; Lone, Reyaz Ahmad; Ashraf, Hakeem Zubair; Dar, Abdul Majeed; Bhat, M A; Singh, Shyam; Bijli, Akram Hussain; Irshad, Ifat

2011-01-01

Bear mauling is rarely reported in medical literature due to its rare occurrence. Present study was undertaken to describe the pattern and management of bear maul vascular injuries in Kashmir. Study of patients with bear maul vascular injury from 1(st) Jan 2004 to 31(st) Dec. 2008. Fifteen patients with bear maul vascular injury were studied. All patients of bear maul without vascular injury were excluded from the study. Most of the patients were treated by reverse saphenous vein graft or end to end anastomosis. Most common complication was wound infection (20%) followed by graft occlusion (13.33%). There was no operative death. Bear attacks are very common in Kashmir. Vascular injury due to bear maul needs prompt resuscitation and revascularization. Results are very good provided timely intervention for revascularization is done.

Vascular Complications of Pancreatitis: Role of Interventional Therapy

Energy Technology Data Exchange (ETDEWEB)

Barge, Jaideep U.; Lopera, Jorge E. [University of Texas Health Science Center, San Antonio (United States)

2012-02-15

Major vascular complications related to pancreatitis can cause life-threatening hemorrhage and have to be dealt with as an emergency, utilizing a multidisciplinary approach of angiography, endoscopy or surgery. These may occur secondary to direct vascular injuries, which result in the formation of splanchnic pseudoaneurysms, gastrointestinal etiologies such as peptic ulcer disease and gastroesophageal varices, and post-operative bleeding related to pancreatic surgery. In this review article, we discuss the pathophysiologic mechanisms, diagnostic modalities, and treatment of pancreatic vascular complications, with a focus on the role of minimally-invasive interventional therapies such as angioembolization, endovascular stenting, and ultrasound-guided percutaneous thrombin injection in their management.

PanVascular medicine. 2. ed.

Energy Technology Data Exchange (ETDEWEB)

Lanzer, Peter (ed.) [Health Care Center Bitterfeld (Germany). Division of Cardiovascular Disease

2015-06-01

Vascular management and care has become a truly multidisciplinary enterprise as the number of specialists involved in the treatment of patients with vascular diseases has steadily increased. While in the past, treatments were delivered by individual specialists, in the twenty-first century a team approach is without doubt the most effective strategy. In order to promote professional excellence in this dynamic and rapidly evolving field, a shared knowledge base and interdisciplinary standards need to be established. Pan Vascular Medicine, 2nd edition has been designed to offer such an interdisciplinary platform, providing vascular specialists with state-of-the art descriptive and procedural knowledge. Basic science, diagnostics, and therapy are all comprehensively covered. In a series of succinct, clearly written chapters, renowned specialists introduce and comment on the current international guidelines and present up-to-date reviews of all aspects of vascular care.

PanVascular medicine. 2. ed.

International Nuclear Information System (INIS)

Lanzer, Peter

2015-01-01

Vascular management and care has become a truly multidisciplinary enterprise as the number of specialists involved in the treatment of patients with vascular diseases has steadily increased. While in the past, treatments were delivered by individual specialists, in the twenty-first century a team approach is without doubt the most effective strategy. In order to promote professional excellence in this dynamic and rapidly evolving field, a shared knowledge base and interdisciplinary standards need to be established. Pan Vascular Medicine, 2nd edition has been designed to offer such an interdisciplinary platform, providing vascular specialists with state-of-the art descriptive and procedural knowledge. Basic science, diagnostics, and therapy are all comprehensively covered. In a series of succinct, clearly written chapters, renowned specialists introduce and comment on the current international guidelines and present up-to-date reviews of all aspects of vascular care.

[Distribution diversity of integrins and calcium channels on major human and mouse host cells of Leptospira species].

Science.gov (United States)

Li, Cheng-xue; Zhao, Xin; Qian, Jing; Yan, Jie

2012-07-01

To determine the distribution of integrins and calcium channels on major human and mouse host cells of Leptospira species. The expression of β1, β2 and β3 integrins was detected with immunofluorescence assay on the surface of human monocyte line THP-1, mouse mononuclear-macrophage-like cell line J774A.1, human vascular endothelial cell line HUVEC, mouse vascular endothelial cell EOMA, human hepatocyte line L-02, mouse hepatocyte line Hepa1-6, human renal tubular epithelial cell line HEK-293, mouse glomerular membrane epithelial cell line SV40-MES13, mouse collagen blast line NIH/3T3, human and mouse platelets. The distribution of voltage gate control calcium channels Cav3.1, Cav3.2, Cav3.3 and Cav2.3, and receptor gate calcium channels P(2)X(1), P(2)2X(2), P(2)X(3), P(2)X(4), P(2)X(5), P(2)X(6) and P(2)X(7) were determined with Western blot assay. β1 integrin proteins were positively expressed on the membrane surface of J774A.1, THP-1, HUVEC, EOMA, L-02, Hepa1-6 and HEK-239 cells as well as human and mouse platelets. β2 integrin proteins were expressed on the membrane surface of J774A.1, THP-1, HUVEC, EOMA, and NIH/3T3 cells. β3 integrin proteins were expressed on the membrane surface of J774A.1, THP-1, HUVEC, EOMA, Hepa1-6, HEK-239 and NIH/3T3 cells as well as human and mouse platelets. P(2)X(1) receptor gate calcium channel was expressed on the membrane surface of human and mouse platelets, while P(2)X(5) receptor gate calcium channel was expressed on the membrane surface of J774A.1, THP-1, L-02, Hepa1-6, HEK-239 and HUVEC cells. However, the other calcium channels were not detected on the tested cell lines or platelets. There is a large distribution diversity of integrins and calcium channel proteins on the major human and mouse host cells of Leptospira species, which may be associated with the differences of leptospira-induced injury in different host cells.

[The future of vascular medicine].

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Kroeger, K; Luther, B

2014-10-01

In the future vascular medicine will still have a great impact on health of people. It should be noted that the aging of the population does not lead to a dramatic increase in patient numbers, but will be associated with a changing spectrum of co-morbidities. In addition, vascular medical research has to include the intensive care special features of vascular patients, the involvement of vascular medicine in a holistic concept of fast-track surgery, a geriatric-oriented intensive monitoring and early geriatric rehabilitation. For the future acceptance of vascular medicine as a separate subject area under delimitation of cardiology and radiology is important. On the other hand, the subject is so complex and will become more complex in future specialisations that mixing of surgery and angiology is desirable, with the aim to preserve the vascular surgical knowledge and skills on par with the medical and interventional measures and further develop them. Only large, interdisciplinary guided vascular centres will be able to provide timely diagnosis and therapy, to deal with the growing multi-morbidity of the patient, to perform complex therapies even in an acute emergency and due to sufficient number of cases to present with well-trained and experienced teams. These requirements are mandatory to decrease patients' mortality step by step. Georg Thieme Verlag KG Stuttgart · New York.

Vascular neurocognitive disorders and the vascular risk factors

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Carmen V. Albu

2018-04-01

Full Text Available Dementias are clinical neurodegenerative diseases characterized by permanent and progressive transformation of cognitive functions such as memory, learning capacity, attention, thinking, language, passing judgments, calculation or orientation. Dementias represent a relatively frequent pathology, encountered at about 10% of the population of 65-year olds and 20% of the population of 80-year olds. This review presents the main etiological forms of dementia, which include Alzheimer form of dementia, vascular dementia, dementia associated with alpha-synucleionopathies, and mixed forms. Regarding vascular dementia, the risk factors are similar to those for an ischemic or hemorrhagic cerebrovascular accident: arterial hypertension, diabetes mellitus, dyslipidemia, smoking, obesity, age, alcohol consumption, cerebral atherosclerosis/ arteriosclerosis. Several studies show that efficient management of the vascular risk factors can prevent the expression and/ or progression of dementia. Thus, lifestyle changes such as stress reduction, regular physical exercise, decreasing dietary fat, multivitamin supplementation, adequate control of blood pressure and serum cholesterol, and social integration and mental stimulation in the elderly population are important factors in preventing or limiting the symptoms of dementia, a disease with significant individual, social, and economic implications.

Effects of (-)-desmethoxyverapamil on heart and vascular smooth muscle

International Nuclear Information System (INIS)

Nawrath, H.; Raschack, M.

1987-01-01

(-)-Desmethoxyverapamil [also known as (-)-devapamil or (-)-D888] has been developed as a verapamil type radioligand for the study of calcium channels. In the present investigation, the effects of (-)-desmethoxyverapamil on action potential (AP) and force of contraction in heart muscle preparations and on tension and 45 Ca influx in vascular smooth muscle are described. In part, the effects were compared with the (+)-isomer of desmethoxyverapamil and the isomers of both verapamil and methoxyverapamil. In atrial and/or ventricular heart muscle preparations from guinea pigs, cats and man, (-)-desmethoxyverapamil decreased the force of contraction and shortened the AP duration. Slow response APs were depressed, whereas dV/dtmax of phase 0 of the AP remained unchanged. The rank order of potency of the (-)-isomers was as follows: desmethoxyverapamil greater than methoxyverapamil greater than verapamil. Potassium-induced contractures and 45 Ca influx were depressed by the (-)-isomers of desmethoxyverapamil, methoxyverapamil and verapamil in the same potency rank order as observed in heart muscle. The (+)-isomers exerted qualitatively similar effects at about 10 to 200 times higher concentrations. Correspondingly, the increase in potency of the racemic mixtures of the drugs was accompanied by increases in stereoselectivity. It is concluded that (-)-desmethoxyverapamil is the most potent stereoselective calcium antagonist of the verapamil type with respect to its effects on heart and vascular smooth muscle

Effects of (-)-desmethoxyverapamil on heart and vascular smooth muscle

Energy Technology Data Exchange (ETDEWEB)

Nawrath, H.; Raschack, M.

1987-09-01

(-)-Desmethoxyverapamil (also known as (-)-devapamil or (-)-D888) has been developed as a verapamil type radioligand for the study of calcium channels. In the present investigation, the effects of (-)-desmethoxyverapamil on action potential (AP) and force of contraction in heart muscle preparations and on tension and /sup 45/Ca influx in vascular smooth muscle are described. In part, the effects were compared with the (+)-isomer of desmethoxyverapamil and the isomers of both verapamil and methoxyverapamil. In atrial and/or ventricular heart muscle preparations from guinea pigs, cats and man, (-)-desmethoxyverapamil decreased the force of contraction and shortened the AP duration. Slow response APs were depressed, whereas dV/dtmax of phase 0 of the AP remained unchanged. The rank order of potency of the (-)-isomers was as follows: desmethoxyverapamil greater than methoxyverapamil greater than verapamil. Potassium-induced contractures and /sup 45/Ca influx were depressed by the (-)-isomers of desmethoxyverapamil, methoxyverapamil and verapamil in the same potency rank order as observed in heart muscle. The (+)-isomers exerted qualitatively similar effects at about 10 to 200 times higher concentrations. Correspondingly, the increase in potency of the racemic mixtures of the drugs was accompanied by increases in stereoselectivity. It is concluded that (-)-desmethoxyverapamil is the most potent stereoselective calcium antagonist of the verapamil type with respect to its effects on heart and vascular smooth muscle.

Arterial complications of vascular Ehlers-Danlos syndrome.

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Eagleton, Matthew J

2016-12-01

Vascular Ehlers-Danlos syndrome (EDS) is a relatively rare genetic syndrome that occurs owing to disorders in the metabolism of fibrillary collagen. These defects affect the soft connective tissues resulting in abnormalities in the skin, joints, hollow organs, and blood vessels. Patients with these defects frequently present at a young age with spontaneous arterial complications involving the medium-sized arteries. Complications involving the hollow organs, such as spontaneous colonic perforation, are observed as well. Given the fragility of the soft tissue, open and endovascular intervention on patients with vascular EDS is fraught with high complication rates. A PubMed search was performed to identify manuscripts published related to vascular EDS. This search included more than 747 articles. These findings were cross-referenced using key terms, including endovascular, embolization, surgery, genetics, pathophysiology, connective tissue disorders, vascular complications, systematic review, type III collagen, and COL3A1. The references in key articles and review articles were evaluated for additional resources not identified in the PubMed search. Care must be taken to balance the risk of intervention vs the risk of continued observation. Life-threatening hemorrhage, however, mandates intervention. With careful, altered approaches to tissue handling, endovascular approaches may provide a safer option for managing the arterial complications observed in patients with vascular EDS. Additional hope may also be found in the use of pharmacologic agents that reduce the incidence and severity of the arterial complications. Copyright © 2016 Society for Vascular Surgery. Published by Elsevier Inc. All rights reserved.

Benfotiamine counteracts smoking-induced vascular dysfunction in healthy smokers.

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Stirban, Alin; Nandrean, Simona; Kirana, Stanley; Götting, Christian; Veresiu, Ioan Andrei; Tschoepe, Diethelm

2012-01-01

Background. Smoking induces endothelial dysfunction (ED) mainly by exacerbating oxidative stress (OS) and inflammation. Benfotiamine, a thiamine prodrug with high bioavailability, prevents nicotine-induced vascular dysfunction in rats. It remained unknown whether this effect also occurs in humans. Methods. Therefore, 20 healthy volunteers (mean age: 38 years) were investigated twice, 7-10 days apart in a randomized, cross-over, and investigator-blinded design. Vascular function was assessed by flow-mediated vasodilatation (FMD) of the brachial artery and by measurements of the soluble vascular cell adhesion molecule (sVCAM)-1. Investigations were performed after an overnight fast as well as 20 minutes after one cigarette smoking. On another day, the same procedure was applied following a 3-day oral therapy with benfotiamine (1050 mg/day). Ten patients were randomized to start with smoking alone, and ten started with benfotiamine. Results. Results are expressed as (mean ± SEM). Smoking acutely induced a decrease in FMD by 50% ((∗∗)P benfotiamine treatment to 25%(∗§) ((∗)P benfotiamine. The endothelium-independent vasodilatation remained unaltered between days. Conclusion. In healthy volunteers, smoking blunts vascular function mirrored by a decrease in FMD and an increase in sVCAM-1. Short-term treatment with benfotiamine significantly reduces these effects, showing protective vascular properties.

A biodegradable vascularizing membrane: a feasibility study.

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Kaushiva, Anchal; Turzhitsky, Vladimir M; Darmoc, Marissa; Backman, Vadim; Ameer, Guillermo A

2007-09-01

Regenerative medicine and in vivo biosensor applications require the formation of mature vascular networks for long-term success. This study investigated whether biodegradable porous membranes could induce the formation of a vascularized fibrous capsule and, if so, the effect of degradation kinetics on neovascularization. Poly(l-lactic acid) (PLLA) and poly(dl-lactic-co-glycolic) acid (PLGA) membranes were created by a solvent casting/salt leaching method. Specifically, PLLA, PLGA 75:25 and PLGA 50:50 polymers were used to vary degradation kinetics. The membranes were designed to have an average 60mum pore diameter, as this pore size has been shown to be optimal for inducing blood vessel formation around nondegradable polymer materials. Membrane samples were imaged by scanning electron microscopy at several time points during in vitro degradation to assess any changes in pore structure. The in vivo performance of the membranes was assessed in Sprague-Dawley rats by measuring vascularization within the fibrous capsule that forms adjacent to implants. The vascular density within 100microm of the membranes was compared with that seen in normal tissue, and to that surrounding the commercially available vascularizing membrane TheraCyte. The hemoglobin content of tissue containing the membranes was measured by four-dimensional elastic light scattering as a novel method to assess tissue perfusion. Results from this study show that slow-degrading membranes induce greater amounts of neovascularization and a thinner fibrous capsule relative to fast degrading membranes. These results may be due both to an initially increased number of macrophages surrounding the slower degrading membranes and to the maintenance of their initial pore structure.

Performance Analysis of Iterative Channel Estimation and Multiuser Detection in Multipath DS-CDMA Channels

Science.gov (United States)

Li, Husheng; Betz, Sharon M.; Poor, H. Vincent

2007-05-01

This paper examines the performance of decision feedback based iterative channel estimation and multiuser detection in channel coded aperiodic DS-CDMA systems operating over multipath fading channels. First, explicit expressions describing the performance of channel estimation and parallel interference cancellation based multiuser detection are developed. These results are then combined to characterize the evolution of the performance of a system that iterates among channel estimation, multiuser detection and channel decoding. Sufficient conditions for convergence of this system to a unique fixed point are developed.

Pioglitazone Attenuates Vascular Fibrosis in Spontaneously Hypertensive Rats

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Dengfeng Gao

2012-01-01

Full Text Available Objective. We sought to investigate whether the peroxisome proliferator-activated receptor-γ (PPAR-γ ligand pioglitazone can attenuate vascular fibrosis in spontaneously hypertensive rats (SHRs and explore the possible molecular mechanisms. Methods. SHRs (8-week-old males were randomly divided into 3 groups (n=8 each for treatment: pioglitazone (10 mg/kg/day, hydralazine (25 mg/kg/day, or saline. Normal male Wistar Kyoto (WKY rats (n=8 served as normal controls. Twelve weeks later, we evaluated the effect of pioglitazone on vascular fibrosis by Masson’s trichrome and immunohistochemical staining of collagen III and real-time RT-PCR analysis of collagen I, III and fibronectin mRNA.Vascular expression of PPAR-γ and connective tissue growth factor (CTGF and transforming growth factor-β (TGF-β expression were evaluated by immunohistochemical staining, western blot analysis, and real-time RT-PCR. Results. Pioglitazone and hydralazine treatment significantly decreased systolic blood pressure in SHRs. Masson’s trichrome staining for collagen III and real-time RT-PCR analysis of collagen I, III and fibronectin mRNA indicated that pioglitazone significantly inhibited extracellular matrix production in the aorta. Compared with Wistar Kyoto rats, SHRs showed significantly increased vascular CTGF expression. Pioglitazone treatment significantly increased PPAR-γ expression and inhibited CTGF expression but had no effect on TGF-β expression. Conclusions. The results indicate that pioglitazone attenuated vascular fibrosis in SHRs by inhibiting CTGF expression in a TGF-β-independent mechanism.

Vascular and valvular calcifications in chronic hemodialysis patients

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María Elena Bruzzone

2014-12-01

Full Text Available Introduction: Vascular and valvular calcifications are a frequent complication in dialyzed patients and are connected to an increased morbi-mortality. Many radiological methods (TAC multiple slices and with electrons emission have been used to investigate the presence of vascular calcifications in this population, but only few works have been focused on simple radiology. Objectives: The objectives of this work are to evaluate vascular calcifications by means of Kauppila index in hemodialysis prevalent patients, identify linked risk factors and determine their association with heart valves calcification. Methods: 95 stable patients under hemodialysis were surveyed during a period of 6 months longer. Abdominal Rx simple profile were performed on all patients to evaluate calcification of abdominal aorta by Kauppila index and twodimensional echocardiogram to detect valvular calcifications. Data were collected about sex, age, diabetes, Hypertension, tabaquism, dislipemia and bone-mineral metabolism. Results: 64.5% of the patients showed vascular calcifications. Average Kauppila index was 6.25. Age and time on dialysis correlated with vascular calcifications. In 31.6 % of individuals valvular calcifications were found, which presented significant association with diabetes and Kauppila Index. Conclusions: Vascular and valvular calcifications were frequent in the surveyed population. Kauppila index correlated with age, time on dialysis and valvular calcifications. Heart valves calcification was associated with diabetes.

White matter damage and glymphatic dysfunction in a model of vascular dementia in rats with no prior vascular pathologies.

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Venkat, Poornima; Chopp, Michael; Zacharek, Alex; Cui, Chengcheng; Zhang, Li; Li, Qingjiang; Lu, Mei; Zhang, Talan; Liu, Amy; Chen, Jieli

2017-02-01

We investigated cognitive function, axonal/white matter (WM) changes and glymphatic function of vascular dementia using a multiple microinfarction (MMI) model in retired breeder (RB) rats. The MMI model induces significant (p rats subjected to MMI exhibit significant axonal/WM damage identified by decreased myelin thickness, oligodendrocyte progenitor cell numbers, axon density, synaptic protein expression in the cortex and striatum, cortical neuronal branching, and dendritic spine density in the cortex and hippocampus compared with age-matched controls. MMI evokes significant dilation of perivascular spaces as well as water channel dysfunction indicated by decreased Aquaporin-4 expression around blood vessels. MMI-induced glymphatic dysfunction with delayed cerebrospinal fluid penetration into the brain parenchyma via paravascular pathways as well as delayed waste clearance from the brain. The MMI model in RB rats decreases Aquaporin-4 and induces glymphatic dysfunction which may play an important role in MMI-induced axonal/WM damage and cognitive deficits. Copyright © 2016 Elsevier Inc. All rights reserved.

Acceleration of vascularized bone tissue-engineered constructs in a large animal model combining intrinsic and extrinsic vascularization.

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Weigand, Annika; Beier, Justus P; Hess, Andreas; Gerber, Thomas; Arkudas, Andreas; Horch, Raymund E; Boos, Anja M

2015-05-01

During the last decades, a range of excellent and promising strategies in Bone Tissue Engineering have been developed. However, the remaining major problem is the lack of vascularization. In this study, extrinsic and intrinsic vascularization strategies were combined for acceleration of vascularization. For optimal biomechanical stability of the defect site and simplifying future transition into clinical application, a primary stable and approved nanostructured bone substitute in clinically relevant size was used. An arteriovenous (AV) loop was microsurgically created in sheep and implanted, together with the bone substitute, in either perforated titanium chambers (intrinsic/extrinsic) for different time intervals of up to 18 weeks or isolated Teflon(®) chambers (intrinsic) for 18 weeks. Over time, magnetic resonance imaging and micro-computed tomography (CT) analyses illustrate the dense vascularization arising from the AV loop. The bone substitute was completely interspersed with newly formed tissue after 12 weeks of intrinsic/extrinsic vascularization and after 18 weeks of intrinsic/extrinsic and intrinsic vascularization. Successful matrix change from an inorganic to an organic scaffold could be demonstrated in vascularized areas with scanning electron microscopy and energy dispersive X-ray spectroscopy. Using the intrinsic vascularization method only, the degradation of the scaffold and osteoclastic activity was significantly lower after 18 weeks, compared with 12 and 18 weeks in the combined intrinsic-extrinsic model. Immunohistochemical staining revealed an increase in bone tissue formation over time, without a difference between intrinsic/extrinsic and intrinsic vascularization after 18 weeks. This study presents the combination of extrinsic and intrinsic vascularization strategies for the generation of an axially vascularized bone substitute in clinically relevant size using a large animal model. The additional extrinsic vascularization promotes tissue

Social media in vascular surgery.

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Indes, Jeffrey E; Gates, Lindsay; Mitchell, Erica L; Muhs, Bart E

2013-04-01

There has been a tremendous growth in the use of social media to expand the visibility of various specialties in medicine. The purpose of this paper is to describe the latest updates on some current applications of social media in the practice of vascular surgery as well as existing limitations of use. This investigation demonstrates that the use of social networking sites appears to have a positive impact on vascular practice, as is evident through the incorporation of this technology at the Cleveland Clinic and by the Society for Vascular Surgery into their approach to patient care and physician communication. Overall, integration of social networking technology has current and future potential to be used to promote goals, patient awareness, recruitment for clinical trials, and professionalism within the specialty of vascular surgery. Copyright © 2013 Society for Vascular Surgery. Published by Mosby, Inc. All rights reserved.

Radiological findings and interventions for iatrogenic vascular injuries

International Nuclear Information System (INIS)

Lee, Kyoung Ho; Chung, Jin Wook; Kim, Tae Kyoung; Han, Sang Wook; Lee, Jong Seog; Park, Jae Hyung; Kim, Jong Hyo; Han, Man Chung

1998-01-01

The purpose of this study is to evaluate the radiological findings and effectiveness of radiological interventions in patients with iatrogenic vascular injuries. We analyzed 50 patients with iatrogenic vascular injuries treated with radiological intervention. The causes of injuries were surgery (n=20), cardiovascular intervention (n=15), non-cardiovascular radiological intervention (n=14), and endoscopic intervention (n=1). The injury had resulted in hemorrhage in 35 cases. The iliac and/or femoral, hepatic, and renal vessels were commonly injured. Angiography, ultrasonography with Doppler examination, CT, and CT angiography were performed to diagnose vascular injuries and guide the radiological intervention. The mean follow-up period was 23 months and in 16 cases was more than one year. the major radiological findings were extravasation, pseudoaneurysm, arteriovenous shunt, or vascular obstruction. To control these lesions, radiological interventions such as embolization (n=36), local urokinase administration, stent insertion, foreign body removal, ultrasonography-guided compression, or stent-graft insertion were performed. The clinical problems were immediately controlled by the single trials of radiological interventions and did not recur in 40 cases (80%). Radiological examinations and interventions are useful in cases with iatrogenic vascular injuries. (author). 14 refs., 4 figs

Vascular elastic photoacoustic tomography in humans

Science.gov (United States)

Hai, Pengfei; Zhou, Yong; Liang, Jinyang; Li, Chiye; Wang, Lihong V.

2016-03-01

Quantification of vascular elasticity can help detect thrombosis and prevent life-threatening conditions such as acute myocardial infarction or stroke. Here, we propose vascular elastic photoacoustic tomography (VE-PAT) to measure vascular elasticity in humans. VE-PAT was developed by incorporating a linear-array-based photoacoustic computed tomography system with a customized compression stage. By measuring the deformation of blood vessels under uniaxial loading, VE-PAT was able to quantify the vascular compliance. We first demonstrated the feasibility of VE-PAT in blood vessel phantoms. In large vessel phantoms, VE-PAT detected a decrease in vascular compliance due to simulated thrombosis, which was validated by a standard compression test. In small blood vessel phantoms embedded 3 mm deep in gelatin, VE-PAT detected elasticity changes at depths that are difficult to image using other elasticity imaging techniques. We then applied VE-PAT to assess vascular compliance in a human subject and detected a decrease in vascular compliance when an occlusion occurred downstream from the measurement point, demonstrating the potential of VE-PAT in clinical applications such as detection of deep venous thrombosis.

Diagnosis and management of vascular diseases

International Nuclear Information System (INIS)

Fan Xindong; Zheng Lianzhou

2011-01-01

Vascular disorders mainly include hemangiomas and vascular malformations, and constitute some of the most difficult diagnostic and therapeutic enigmas that can be encountered in the clinical practice. The clinical presentations are extremely variable and can range from an asymptomatic birthmark to life-threatening congestive heart failure. Attributing any of these extremely varied symptoms that a patients may present with to a vascular malformation may be a challenge to the most experienced clinical. This problem is compounded by the extreme rarity of these vascular lesions. If a clinician meets such a patient once every few years, it will be extremely difficult for the physicians to gain a steep learning curve. In such circumstances, it is difficult to formulate a standard of diagnosis and treatment for these vascular disorders. This paper aims to make a comprehensive and detailed description of the classification and diagnosis of the vascular disorders, the common used embolization agents, the concepts of interventional diagnosis and management and the therapies of various hemangiomas and vascular malformations. (authors)

VASCULAR REMODELING IN HYPERTENSION: ANGIOGENESIS FEATURES

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L. A. Haisheva

2014-07-01

Full Text Available Aim — cross-sectional study of changes in various segments of the vascular bed in arterial hypertension (AH, defining the role of inducers and inhibitors of angiogenesis in these processes.Materials and methods. The study included 99 patients with arterial hypertension of I–II degree, average age of 63.2 ± 2.6 years, diseaseduration 9.2 ± 7.2 years.Results. It was found that patients with arterial hypertension have disorders in all segments of vascular bed: endothelial dysfunction (highvWF, microcirculatory disorders, and increased pulse wave velocity (PWV of elastic-type vessels. The level of angioginesis factors doesnot depend on such parameters as gender, age, body mass index. Smoking and duration of hypertension influence on vascular endothelialgrowth factor raise and endostatin levels are higher in patients with family history of cardiovascular diseases. Duration of disease is directlycorrelated with microcirculatory disorders and the PWV, correlation between microcirculatory disorders and pulse wave velocity indicatetheir common processes.

Vascular dysfunction in preeclampsia.

Science.gov (United States)

Brennan, Lesley J; Morton, Jude S; Davidge, Sandra T

2014-01-01

Preeclampsia is a complex disorder which affects an estimated 5% of all pregnancies worldwide. It is diagnosed by hypertension in the presence of proteinuria after the 20th week of pregnancy and is a prominent cause of maternal morbidity and mortality. As delivery is currently the only known treatment, preeclampsia is also a leading cause of preterm delivery. Preeclampsia is associated with maternal vascular dysfunction, leading to serious cardiovascular risk both during and following pregnancy. Endothelial dysfunction, resulting in increased peripheral resistance, is an integral part of the maternal syndrome. While the cause of preeclampsia remains unknown, placental ischemia resulting from aberrant placentation is a fundamental characteristic of the disorder. Poor placentation is believed to stimulate the release of a number of factors including pro- and antiangiogenic factors and inflammatory activators into the maternal systemic circulation. These factors are critical mediators of vascular function and impact the endothelium in distinctive ways, including enhanced endothelial oxidative stress. The mechanisms of action and the consequences on the maternal vasculature will be discussed in this review. © 2013 John Wiley & Sons Ltd.

Quality assurance of lower limb venous duplex scans performed by vascular surgeons.

Science.gov (United States)

Kordowicz, A; Ferguson, G; Salaman, R; Onwudike, M

2015-02-01

Duplex scanning is the gold standard for investigating venous reflux; increasingly surgeons perform these scans themselves. There has been no data published analysing the accuracy of Duplex scans performed by vascular surgeons. We aimed to evaluate an objective method of comparing the results of lower limb Duplex scans performed by one consultant vascular surgeon with those performed by a vascular technologist. We assessed 100 legs with symptomatic varicose veins. Each patient underwent two lower limb venous Duplex scans; one performed by a consultant vascular surgeon and one by a vascular technologist. Scan results were randomised and sent to two consultant vascular surgeons blinded to the identity and experience of the sonographer. They were asked to recommend treatment. A k score was calculated in each case to assess the level of agreement between the scans performed by the consultant and the technologist. Eighty-one patients were studied (53 females). The kappa score for assessor 1 was 0.60 (95%CI:0.44-0.75) and for assessor 2 was 0.62 (95%CI:0.48-0.75). k scores >0.60 represent a substantial strength of agreement. Duplex scans performed by this surgeon were comparable to those performed by a vascular technologist. It is possible to quality-assure duplex performed by vascular surgeons without directly observing the scanning process or reviewing digitally recorded images. We propose standardisation of training, assessment and quality assurance for vascular surgeons wishing to perform ultrasound scans.

Cartilage oligomeric matrix protein enhances the vascularization of acellular nerves

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Wei-ling Cui

2016-01-01

Full Text Available Vascularization of acellular nerves has been shown to contribute to nerve bridging. In this study, we used a 10-mm sciatic nerve defect model in rats to determine whether cartilage oligomeric matrix protein enhances the vascularization of injured acellular nerves. The rat nerve defects were treated with acellular nerve grafting (control group alone or acellular nerve grafting combined with intraperitoneal injection of cartilage oligomeric matrix protein (experimental group. As shown through two-dimensional imaging, the vessels began to invade into the acellular nerve graft from both anastomotic ends at day 7 post-operation, and gradually covered the entire graft at day 21. The vascular density, vascular area, and the velocity of revascularization in the experimental group were all higher than those in the control group. These results indicate that cartilage oligomeric matrix protein enhances the vascularization of acellular nerves.

Eight channel fast scalar

Energy Technology Data Exchange (ETDEWEB)

Waddoup, W D; Stubbs, R J [Durham Univ. (UK)

1977-11-01

An eight channel 64-bit scaler has been constructed with a static CMOS memory. Scaling frequencies are independently variable, at each channel, as are the number of bits/channel. The scaler, when used in conjunction with a multichannel charge to time converter results in a very flexible, gated multichannel ADC.

Vascular disease in cocaine addiction.

Science.gov (United States)

Bachi, Keren; Mani, Venkatesh; Jeyachandran, Devi; Fayad, Zahi A; Goldstein, Rita Z; Alia-Klein, Nelly

2017-07-01

Cocaine, a powerful vasoconstrictor, induces immune responses including cytokine elevations. Chronic cocaine use is associated with functional brain impairments potentially mediated by vascular pathology. Although the Crack-Cocaine epidemic has declined, its vascular consequences are increasingly becoming evident among individuals with cocaine use disorder of that period, now aging. Paradoxically, during the period when prevention efforts could make a difference, this population receives psychosocial treatment at best. We review major postmortem and in vitro studies documenting cocaine-induced vascular toxicity. PubMed and Academic Search Complete were used with relevant terms. Findings consist of the major mechanisms of cocaine-induced vasoconstriction, endothelial dysfunction, and accelerated atherosclerosis, emphasizing acute, chronic, and secondary effects of cocaine. The etiology underlying cocaine's acute and chronic vascular effects is multifactorial, spanning hypertension, impaired homeostasis and platelet function, thrombosis, thromboembolism, and alterations in blood flow. Early detection of vascular disease in cocaine addiction by multimodality imaging is discussed. Treatment may be similar to indications in patients with traditional risk-factors, with few exceptions such as enhanced supportive care and use of benzodiazepines and phentolamine for sedation, and avoiding β-blockers. Given the vascular toxicity cocaine induces, further compounded by smoking and alcohol comorbidity, and interacting with aging of the crack generation, there is a public health imperative to identify pre-symptomatic markers of vascular impairments in cocaine addiction and employ preventive treatment to reduce silent disease progression. Copyright © 2017 Elsevier B.V. All rights reserved.

Role of endovascular treatment in vascular injuries

International Nuclear Information System (INIS)

Tahir, M.M.; Haq, T.U.

2012-01-01

Objective: To evaluate retrospectively the results, complications and follow-up of patients after endovascular treatment of vascular injuries. Methods: Fifty transcatheter embolisation procedures (TCE) were performed in 46 patients between 1999 and 2008 at the Aga Khan University Hospital, Karachi. Injuries in 14 (30.4%) patients were due to road traffic accident; iatrogenic in 13 (28%); accidental in 6 (13%). Firearms, bomb blasts and earthquake contributed to injuries in 8(17%), 4(8.8%) and 1(2.2%) patients respectively. All patients underwent angiography and had evidence of either active haemorrhage, pseudo-aneurysm, abnormal vascularity or arteriovenous fistula. Follow-up ranged from 1 day to 6 years with mean of 10.5 months. Medical record files, lab results and imaging reports were utilised for the study. Procedure was declared as technically successful when there was cessation of extravasation, occlusion of fistula or exclusion of pseudo-aneurysm in the post-embolisation angiograms. Treatment was deemed clinically successful if there was resolution of the indication for which the procedure was done. Results: Transcatheter embolisation was technically successful in occluding vascular lesions in all 46 (100%) patients. Lesions recurred in 4 (9%) patients who underwent initially successful TCE. These patients were treated effectively with repeated TCE. Three patients died during the same hospital stay and 3 patients died after being discharged from the hospital. All these patients were treated successfully with TCE and had factors other then TCE contributing to their mortality. Conclusion: Transcatheter embolisation for vascular injuries was found to be a satisfactory procedure, with low morbidity and mortality rates. (author)

The vascular pattern in the flower of some Mesembryanthemaceae: Aptenia cordifolia and Dorotheanthus bellidiformis. The effect of an ontogenetical shifting on the vascular pattern and vascular conservatism

NARCIS (Netherlands)

Meulen-Bruijns, van der C.

1976-01-01

1. The vascular pattern in the flower at various stages of maturity of Aptenia cordifolia and Dorotheanthus bellidiformis is examined. 2. The vascular pattern of Dorotheanthus has been compared with that of Aptenia: typologically, Dorotheanthus is derived from Aptenia. 3. The vascular pattern of

Escleroterapia con bleomicina en malformaciones vasculares de bajo flujo: Experiencia y revisión del tema Bleomycin sclerotherapy for low-flow vascular malformations: our experience and literature review

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F. Lobo Bailón

2012-12-01

Full Text Available Las anomalías vasculares son lesiones típicas de los pacientes pediátricos y se dividen en dos categorías: tumores vasculares y malformaciones vasculares de alto y bajo flujo. Estas últimas pueden tratarse de diversos modos: laserterapia, drenaje, aspiración, cirugía o escleroterapia, dependiendo del tipo de lesión y de su localización. Entre los agentes esclerosantes utilizados, la bleomicina ha demostrado tener buenos resultados en el tratamiento de estas lesiones. En este artículo presentamos nuestra experiencia en el tratamiento de las malformaciones vasculares de bajo flujo mediante escleroterapia con bleomicina intralesional. Desarrollamos un estudio descriptivo retrospectivo sobre 30 pacientes que presentaban malformación vascular de bajo flujo y fueron tratados con bleomicina intralesional. Los resultados fueron buenos o excelentes en 22 pacientes y regulares o malos en los 8 restantes. De acuerdo a nuestra casuística y a la literatura revisada, la escleroterapia con bleomicina es una alternativa terapéutica eficaz y segura en el tratamiento de las malformaciones vasculares de bajo flujo.Vascular anomalies are common in children and can be divided into two categories, vascular tumours and vascular malformations: high-flow or low-flow. The latter can be treated in different ways such as lasertherapy, drainage, aspiration, surgery or sclerotherapy depending on the type and location of the lesion. Among the accepted sclerosing agents, bleomycin has proven good results in the treatment of this condition. Herein we present our experience in the treatment of low-flow vascular malformations with intralesional bleomycin injection. This is a retrospective, descriptive study with 30 patients presenting a low-flow vascular malformation treated with intralesional bleomycin injection. Our results are good or excellent in 22 patients and poor in the other 8. According to our case series and the consulted literature, sclerotherapy with

Channel and Timeslot Co-Scheduling with Minimal Channel Switching for Data Aggregation in MWSNs

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Sanggil Yeoum

2017-05-01

Full Text Available Collision-free transmission and efficient data transfer between nodes can be achieved through a set of channels in multichannel wireless sensor networks (MWSNs. While using multiple channels, we have to carefully consider channel interference, channel and time slot (resources optimization, channel switching delay, and energy consumption. Since sensor nodes operate on low battery power, the energy consumed in channel switching becomes an important challenge. In this paper, we propose channel and time slot scheduling for minimal channel switching in MWSNs, while achieving efficient and collision-free transmission between nodes. The proposed scheme constructs a duty-cycled tree while reducing the amount of channel switching. As a next step, collision-free time slots are assigned to every node based on the minimal data collection delay. The experimental results demonstrate that the validity of our scheme reduces the amount of channel switching by 17.5%, reduces energy consumption for channel switching by 28%, and reduces the schedule length by 46%, as compared to the existing schemes.

The diabetic foot - modern possibilities of vascular reconstruction

International Nuclear Information System (INIS)

Arlart, I.P.

1992-01-01

Arterial vascular disease in diabetic patients includes both microangiopathy and macroangiopathy. Macroangiopathy, i.e. stenoses of occlusions of the ilio-femoro-popliteal arteries and crural arteries, can be treated by surgical vascular reconstructions and radiological procedures such as recanalisation via catheter and CT-guided lumbar sympathetic trunk, neurolysis. In this paper the different therapeutic techniques are presented in respect of indications and results particularly in the diabetic patients. (orig.) [de

Accelerated Vascular Aging as a Paradigm for Hypertensive Vascular Disease: Prevention and Therapy.

Science.gov (United States)

Barton, Matthias; Husmann, Marc; Meyer, Matthias R

2016-05-01

Aging is considered the most important nonmodifiable risk factor for cardiovascular disease and death after age 28 years. Because of demographic changes the world population is expected to increase to 9 billion by the year 2050 and up to 12 billion by 2100, with several-fold increases among those 65 years of age and older. Healthy aging and prevention of aging-related diseases and associated health costs have become part of political agendas of governments around the world. Atherosclerotic vascular burden increases with age; accordingly, patients with progeria (premature aging) syndromes die from myocardial infarctions or stroke as teenagers or young adults. The incidence and prevalence of arterial hypertension also increases with age. Arterial hypertension-like diabetes and chronic renal failure-shares numerous pathologies and underlying mechanisms with the vascular aging process. In this article, we review how arterial hypertension resembles premature vascular aging, including the mechanisms by which arterial hypertension (as well as other risk factors such as diabetes mellitus, dyslipidemia, or chronic renal failure) accelerates the vascular aging process. We will also address the importance of cardiovascular risk factor control-including antihypertensive therapy-as a powerful intervention to interfere with premature vascular aging to reduce the age-associated prevalence of diseases such as myocardial infarction, heart failure, hypertensive nephropathy, and vascular dementia due to cerebrovascular disease. Finally, we will discuss the implementation of endothelial therapy, which aims at active patient participation to improve primary and secondary prevention of cardiovascular disease. Copyright © 2016 Canadian Cardiovascular Society. Published by Elsevier Inc. All rights reserved.

Anti-vascular endothelial growth factors for choroidal neovascularization secondary to choroidal osteoma: Long-term results

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T Lekha

2015-01-01

Full Text Available Choroidal osteoma is an uncommon benign osseous intraocular tumor typically seen unilaterally in young women. Visual loss can occur due to choroidal neovascularization (CNV complicating osteoma. We report a rare case of bilateral choroidal osteoma with secondary CNV in a young male and the long-term results following anti-vascular endothelial growth factor (VEGF therapy. A 30-year-old male with history of defective vision in both eyes since several years and recent worsening in the right eye (RE since 2 months was found to have bilateral macular osteoma with CNV in the RE based on clinical evaluation, fluorescein angiography, optical coherence tomography, and ultrasonography. Intravitreal injection of ranibizumab at monthly intervals for three doses resulted in resolution of CNV and remained stable for 5 years. Recurrent CNV detected 6 years later responded to an injection of intravitreal bevacizumab and has remained stable till date. Anti-VEGF therapy stabilized the secondary CNV in our patient for 7 years with satisfactory structural and functional outcome, demonstrating the long-term efficacy of this modality of treatment.

The pathology and pathophysiology of vascular dementia.

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Kalaria, Raj N

2017-12-19

Vascular dementia (VaD) is widely recognised as the second most common type of dementia. Consensus and accurate diagnosis of clinically suspected VaD relies on wide-ranging clinical, neuropsychological and neuroimaging measures in life but more importantly pathological confirmation. Factors defining subtypes of VaD include the nature and extent of vascular pathologies, degree of involvement of extra and intracranial vessels and the anatomical location of tissue changes as well as time after the initial vascular event. Atherosclerotic and cardioembolic diseases combined appear the most common subtypes of vascular brain injury. In recent years, cerebral small vessel disease (SVD) has gained prominence worldwide as an important substrate of cognitive impairment. SVD is characterised by arteriolosclerosis, lacunar infarcts and cortical and subcortical microinfarcts and diffuse white matter changes, which involve myelin loss and axonal abnormalities. Global brain atrophy and focal degeneration of the cerebrum including medial temporal lobe atrophy are also features of VaD similar to Alzheimer's disease. Hereditary arteriopathies have provided insights into the mechanisms of dementia particularly how arteriolosclerosis, a major contributor of SVD promotes cognitive impairment. Recently developed and validated neuropathology guidelines indicated that the best predictors of vascular cognitive impairment were small or lacunar infarcts, microinfarcts, perivascular space dilation, myelin loss, arteriolosclerosis and leptomeningeal cerebral amyloid angiopathy. While these substrates do not suggest high specificity, VaD is likely defined by key neuronal and dendro-synaptic changes resulting in executive dysfunction and related cognitive deficits. Greater understanding of the molecular pathology is needed to clearly define microvascular disease and vascular substrates of dementia. Copyright © 2017 Elsevier Ltd. All rights reserved.

Intramuscular vascular malformations of an extremity: findings on MR imaging and pathologic correlation

International Nuclear Information System (INIS)

Kim, E.Y.; Ahn, J.M.; Yoon, H.K.; Do, Y.S.; Kim, S.H.; Choo, S.W.; Choo, I.W.; Suh, Y.L.; Kim, S.M.; Kang, H.S.

1999-01-01

Objective. To analyze the findings of intramuscular vascular malformations of an extremity on MR imaging and to correlate these findings with histopathologic examination.Design and patients. The findings on MR imaging and the medical records of 14 patients with an intramuscular vascular malformation of the extremity were retrospectively studied. All patients underwent surgical excision. Diagnoses were based on the results of pathologic examination. Findings on MR imaging were noted and correlated with the histopathologic findings.Results. Intramuscular vascular malformations of an extremity showed multi-septate, honeycomb, or mixed appearance on MR imaging. Multi-septate areas correlated with dilated and communicating vascular spaces with flattened endothelium. Honeycomb areas corresponded to vascular spaces with inconspicuous small lumina and thickened vascular walls. Areas of increased signal intensity on T2-weighted images were found in all intramuscular vascular malformations. Infiltrative margins were more commonly seen in intramuscular lymphaticovenous malformations. Adherence to neurovascular structures and orientation of the lesion along the long axis of the affected muscle were more commonly seen in intramuscular venous malformations.Conclusions. Intramuscular vascular malformations showed either a multi-septate, honeycomb, or mixed appearance, reflecting the size of the vascular spaces and the thickness of the smooth muscles of the vessel walls. Prediction of the subtype of an intramuscular vascular malformation of an extremity on MR imaging seems to be difficult, although there are associated findings that may be helpful in the differential diagnosis of each subtype. (orig.)

LASER TREATMENT OF BENIGN CUTANEOUS VASCULAR LESIONS

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Uroš Ahčan

2004-07-01

Full Text Available Background. Congenital and acquired vascular lesions of the skin and subcutis are a common health problem from aesthetic and also from psycho-social point of view. However, recent advances in laser technology have enabled an efficient and safe treatment. This study presents our experience with treatment of cutaneous vascular lesions using modern laser systems. Most common benign cutaneous vascular lesions are described.Patients and methods. In years 2002 and 2003, 109 patients, 4 to 80 (mean 39 years old, Fitzpatrick skin type 1–4, with 210 benign cutaneous vascular lesions were treated using the Dualis VP® laser system (Fotona, Slovenia which incorporates the KTP and Nd:YAG lasers. Vascular lesions in the upper layers of the skin with diameter up to 1 mm were treated with the KTP laser (wavelength 532 nm. For larger vessels in deeper layer we used the Nd:YAG laser (wavelength 1064 nm. Patients graded the pain during treatment on a scale of 1–10. Clinical outcomes were evaluated 1–3 months after the last treatment: according to the percentage of clearance of the lesion compared to the adjacent normal skin and for the presence of adverse effects. According to these criteria each lesion was assigned a score: poor (0–25%, fair (26–50%, good (51–75%, excellent (76–100%.Results. Immediate response after application of a laser beam with proper characteristics was whitish-grey discoloration of treated area. Treatment results after 1–3 months were excellent in 48.1%, good 40.9%, fair in 8.6% and poor in 2.4%. Patients without prior anaesthesia graded pain during treatment from 1 to 8 (mean 4.0 and patients with EMLA® anaesthesia from 1 to 6 (mean 2.6. Side effects were frequent but minimal and transient. Erythema disappeared in several days after treatment while crusting persisted for 14 days. 3 permanent hyperpigmentations, 2 permanent hypopigmentations, 2 hypertrophic scars and 1 beam sized atrophic scar were detected at last follow

Early vascular plants in the Czech Republic

OpenAIRE

Uhlířová, Monika

2017-01-01

Vascular plants are characterized as a group of plants, which are already fully adapted to live on the land. Their evolution is a result of a set of adaptations that have required the necessary changes at anatomical and morphological level. Some evidences about the rise of vascular plants appear in the fossil record from the Middle Ordovician in the form of spores and later also from the Early Silurian in the form of megafossils. The aim of the thesis is to briefly describe and discuss the mo...

Vascular injury is associated with increased mortality in winter sports trauma.

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Eun, John C; Bronsert, Michael; Hansen, Kristine; Moulton, Steven L; Jazaeri, Omid; Nehler, Mark; Greenberg, Joshua I

2015-01-01

Trauma is the leading cause of injury and death for individuals aged 1-44 years. Up to 8% of the US population participates in winter sports, and although vascular injuries are uncommon in these activities, little is published in this area. We sought to identify the incidence, injury patterns, and outcomes of vascular injuries resulting from winter sports trauma. Patients with winter sports trauma and the subset with vascular injuries were identified by accessing the National Trauma Data Bank querying years 2007-2010. Patients with and without vascular injuries were then compared. Admission variables included transport time, emergency department hypotension (systolic blood pressure Injury Severity Score ≥ 25, fractures, solid organ injury, and vascular injury. Outcomes were analyzed and associations with vascular injuries were determined. A total of 2,298 patients were identified with winter sports-related trauma and 28 (1.2%) had associated vascular injuries. Overall, the top 3 injuries were head trauma (16.7%), thoracic vertebral fractures (5.5%), and lumbar vertebral fractures (5.1%). The most common associated vascular injures were to the popliteal artery (17.7%), splenic artery (14.7%), and brachial blood vessels (14.7%). In the entire cohort, 1 patient (0.04%) suffered an amputation and 15 patients (0.7%) died. There were no amputations in the vascular injury group. Mortality was 0.6% in patients without a vascular injury compared with 7.1% of those with a vascular injury (P = 0.01). Although vascular injury is an uncommon associated finding in winter sports trauma, it is associated with a significant increase in mortality. These findings highlight the need for rapid identification of traumatic vascular injuries, which predicts worse overall outcomes in this patient population. Copyright © 2015 Elsevier Inc. All rights reserved.

Terror attacks increases the risk of vascular injuries

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Eitan eHeldenberg

2014-05-01

Full Text Available Objectives: Extensive literature exists about military trauma as opposed to the very limited literature regarding terror-related civilian trauma. However, terror-related vascular trauma (VT, as a unique type of injury, is yet to be addressed.Methods: A retrospective analysis of the Israeli National Trauma Registry was performed. All patients in the registry from 09/2000 to 12/2005 were included. The subgroup of patients with documented vascular trauma (VT (N=1,545 was analyzedand further subdivided into those suffering from Terror-related Vascular Trauma (TVT and Non-Terror related Vascular Trauma (NTVT. Both groups were analyzed according to mechanism of trauma, type and severity of injury and treatment.Results: Out of 2,446 terror related trauma admissions 243 sustained TVT (9.9% compared to 1302 VT patients from Non Terror trauma (1.1%. TVT injuries tend to be more complex and most patients were operated on. ICU admissions and hospitallength of stay was higher in the TVT group. Penetrating trauma was the prominent cause of injury among the TVT group. TVT group had a higher proportion of patients with severe injuries (ISS>16 and mortality. Thorax injuries were more frequent in the TVT group. Extremity injuries were the most prevalent vascular injuries in both groups; however NTVT group had more upper extremity injuries, while the TVT group had significantly more lower extremity injuries.Conclusion: Vascular injuries are remarkably more common among terror attack victims than among non-terror trauma victims and the injuries of terror casualties tend to be more complex. The presence of a vascular surgeon will ensure a comprehensive clinical care.

Modelling the development and arrangement of the primary vascular structure in plants.

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Cartenì, Fabrizio; Giannino, Francesco; Schweingruber, Fritz Hans; Mazzoleni, Stefano

2014-09-01

The process of vascular development in plants results in the formation of a specific array of bundles that run throughout the plant in a characteristic spatial arrangement. Although much is known about the genes involved in the specification of procambium, phloem and xylem, the dynamic processes and interactions that define the development of the radial arrangement of such tissues remain elusive. This study presents a spatially explicit reaction-diffusion model defining a set of logical and functional rules to simulate the differentiation of procambium, phloem and xylem and their spatial patterns, starting from a homogeneous group of undifferentiated cells. Simulation results showed that the model is capable of reproducing most vascular patterns observed in plants, from primitive and simple structures made up of a single strand of vascular bundles (protostele), to more complex and evolved structures, with separated vascular bundles arranged in an ordered pattern within the plant section (e.g. eustele). The results presented demonstrate, as a proof of concept, that a common genetic-molecular machinery can be the basis of different spatial patterns of plant vascular development. Moreover, the model has the potential to become a useful tool to test different hypotheses of genetic and molecular interactions involved in the specification of vascular tissues.

99mTc-leukocyte scintigraphy in prosthetic vascular graft infections

International Nuclear Information System (INIS)

Vorne, M.; Laitinen, J.; Lehtonen, J.; Toivio, I.; Mokka, R.; Soini, I.

1989-01-01

The aim of this study was to determine the diagnostic value of scintigraphy with 99m Tc-HMPAO-labelled leukocytes for the detection of prosthetic vascular graft infection. 51 scans were recorded in 19 patients with suspected vascular graft infection and 8 control patients. Three-phase scanning was used at 0.5, 3-6 and 18-24 h. 13 vascular graft infections (10 early, 3 late) were found. 12 of these healed with antibiotics and only one patient with late infection had to be reoperated. None of them died during the follow-up period. The sensitivity was 100% and the specificity 96%. 99m Tc-leukocyte scintigraphy seems a useful tool to detect vascular graft infection and to differentiate it from infections elsewhere. The results suggest that the incidence of vascular graft infection may be greater, and the mortality rate lower, than supposed before. (orig.) [de

The importance of complete follow-up for results after femoro-infrapopliteal vascular surgery

DEFF Research Database (Denmark)

Jensen, L P; Nielsen, O M; Schroeder, T V

1996-01-01

intervals and all data have been recorded prospectively in a vascular registry. As part of a randomised trial on adjuvant medication in femorocrural bypass surgery, 102 patients, operated on between 1990 and 1992 were independently and simultaneously monitored. This subgroup was examined at 3 and 12 months...... is lost to follow-up, since failure to examine the patient for any reason may be related to the patients health. In addition to the number of patients at risk, it is suggested, that life-table plots should be supplemented with information on the number of patients lost to follow-up....

Intermittent injections of osteocalcin reverse autophagic dysfunction and endoplasmic reticulum stress resulting from diet-induced obesity in the vascular tissue via the NFκB-p65-dependent mechanism.

Science.gov (United States)

Zhou, Bo; Li, Huixia; Liu, Jiali; Xu, Lin; Zang, Weijin; Wu, Shufang; Sun, Hongzhi

2013-06-15

The osteoblast-specific secreted molecule osteocalcin behaves as a hormone-regulating glucose and lipid metabolism, but the role of osteocalcin in cardiovascular disease (CVD) is not fully understood. In the present study, we investigated the effect of osteocalcin on autophagy and endoplasmic reticulum (ER) stress secondary to diet-induced obesity in the vascular tissue of mice and in vascular cell models and clarified the intracellular events responsible for osteocalcin-mediated effects. The evidences showed that intermittent injections of osteocalcin in mice fed the high-fat diet were associated with a reduced body weight gain, decreased blood glucose and improved insulin sensitivity compared with mice fed the high-fat diet receiving vehicle. Simultaneously, the administration of osteocalcin not only attenuated autophagy and ER stress but also rescued impaired insulin signaling in vascular tissues of mice fed a high-fat diet. Consistent with these results in vivo, the addition of osteocalcin reversed autophagy and ER stress and restored defective insulin sensitivity in vascular endothelial cells (VECs) and vascular smooth muscle cells (VSMCs) in the presence of tunicamycin or in knockout XBP-1 (a transcription factor which mediates ER stress response) cells or in Atg7(-/-) cells. The protective effects of osteocalcin were nullified by suppression of Akt, mammalian target of rapamycin (mTOR) or nuclear factor kappa B (NFκB), suggesting that osteocalcin inhibits autophagy, ER stress and improves insulin signaling in the vascular tissue and cells under insulin resistance in a NFκB-dependent manner, which may be a promising therapeutic strategies of cardiovascular dysfunction secondary to obesity.

The making of indigenous vascular prosthesis

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Madathipat Unnikrishnan

2016-01-01

Full Text Available Background & objectives: Vascular illnesses are on the rise in India, due to increase in lifestyle diseases and demographic transition, requiring intervention to save life, organ or limbs using vascular prosthesis. The aim of this study was to develop indigenous large diameter vascular graft for treatment of patients with vascular pathologies. Methods: The South India Textile Research Association, at Coimbatore, Tamil Nadu, India, developed seamless woven polyester (Polyethylene terephthalate graft at its research wing. Further characterization and testing followed by clinical trials were conducted at Sree Chitra Tirunal Institute for Medical Sciences and Technology, Thiruvananthapuram, Kerala, India. Fifteen in vivo experiments were carried out in 1992-1994 in pigs as animal model. Controlled (phase I clinical trial in ten patients was performed along with control graft. Thereafter, phase II trial involved 22 patients who underwent multi-centre clinical trial in four centres across India. Results: Laboratory testing showed that polyester graft was non-toxic, non-leeching and non-haemolytic with preserved long-term quality, further confirming in pigs by implanting in thoracic aorta, comparable to control Dacron grafts. Perigraft incorporation and smooth neointima formation which are prime features of excellent healing characteristics, were noted at explantation at planned intervals. Subsequently in the phase I and II clinical trials, all patients had excellent recovery without mortality or device-related adverse events. Patients receiving the test graft were followed up for 10 and 5 years, respectively. Serial clinical, duplex scans and CT angiograms performed periodically confirmed excellent graft performance. Interpretation & conclusions: Indigenously developed Chitra vascular graft was comparable to commercially available Dacron graft, ready for clinical use at affordable cost to patients as against costly imported grafts.

Vascular risk factors, cognitve decline, and dementia

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E Duron

2008-04-01

Full Text Available E Duron, Olivier HanonBroca Hospital, Paris, FranceAbstract: Dementia is one of the most important neurological disorders in the elderly. Aging is associated with a large increase in the prevalence and incidence of degenerative (Alzheimer’s disease and vascular dementia, leading to a devastating loss of autonomy. In view of the increasing longevity of populations worldwide, prevention of dementia has turned into a major public health challenge. In the past decade, several vascular risk factors have been found to be associated with vascular dementia but also Alzheimer’s disease. Some longitudinal studies, have found significant associations between hypertension, diabetus mellitus, and metabolic syndrome, assessed at middle age, and dementia. Studies assessing the link between hypercholesterolemia, atrial fibrillation, smoking, and dementia have given more conflicting results. Furthermore, some studies have highlighted the possible protective effect of antihypertensive therapy on cognition and some trials are evaluating the effects of statins and treatments for insulin resistance. Vascular risk factors and their treatments are a promising avenue of research for prevention of dementia, and further long-term, placebo-controlled, randomized studies, need to be performed.Keywords: dementia, hypertension, diabetus mellitus, hypercholesterolemia, metabolic syndrome

Channel allocation and rate adaptation for relayed transmission over correlated fading channels

KAUST Repository

Hwang, Kyusung

2009-09-01

We consider, in this paper, channel allocation and rate adaptation scheme for relayed transmission over correlated fading channels via cross-layer design. Specifically, jointly considering the data link layer buffer occupancy and channel quality at both the source and relay nodes, we develop an optimal channel allocation and rate adaptation policy for a dual-hop relayed transmission. As such the overall transmit power for the relayed system is minimized while a target packet dropping rate (PDR) due to buffer over flows is guaranteed. In order to find such an optimal policy, the channel allocation and rate adaptation transmission framework is formulated as a constraint Markov decision process (CMDP). The PDR performance of the optimal policy is compared with that of two conventional suboptimal schemes, namely the channel quality based and the buffer occupancy based channel allocation schemes. Numerical results show that for a given power budget, the optimal scheme requires significantly less power than the conventional schemes in order to maintain a target PDR. ©2009 IEEE.

Sensing of Vascular Permeability in Inflamed Vessel of Live Animal

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Sang A Park

2018-01-01

Full Text Available Increase in vascular permeability is a conclusive response in the progress of inflammation. Under controlled conditions, leukocytes are known to migrate across the vascular barriers to the sites of inflammation without severe vascular rupture. However, when inflammatory state becomes excessive, the leakage of blood components may occur and can be lethal. Basically, vascular permeability can be analyzed based on the intensity of blood outflow. To evaluate the amount and rate of leakage in live mice, we performed cremaster muscle exteriorization to visualize blood flow and neutrophil migration. Using two-photon intravital microscopy of the exteriorized cremaster muscle venules, we found that vascular barrier function is transiently and locally disrupted in the early stage of inflammatory condition induced by N-formylmethionyl-leucyl-phenylalanine (fMLP. Measurement of the concentration of intravenously (i.v. injected Texas Red dextran inside and outside the vessels resulted in clear visualization of real-time increases in transient and local vascular permeability increase in real-time manner. We successfully demonstrated repeated leakage from a target site on a blood vessel in association with increasing severity of inflammation. Therefore, compared to other methods, two-photon intravital microscopy more accurately visualizes and quantifies vascular permeability even in a small part of blood vessels in live animals in real time.

Expanded Stem Cells, Stromal-Vascular Fraction, and Platelet-Rich Plasma Enriched Fat: Comparing Results of Different Facial Rejuvenation Approaches in a Clinical Trial.

Science.gov (United States)

Rigotti, Gino; Charles-de-Sá, Luiz; Gontijo-de-Amorim, Natale Ferreira; Takiya, Christina Maeda; Amable, Paola Romina; Borojevic, Radovan; Benati, Donatella; Bernardi, Paolo; Sbarbati, Andrea

2016-03-01

In a previous study, the authors demonstrated that treatment with expanded adipose-derived stem cells or stromal vascular fraction (SVF)-enriched fat modify the pattern of the dermis in human beings, representing a skin rejuvenation effect. Considering that expanded stem cells require a cell factor, the authors wanted to assess similar results by replacing them with platelet-rich plasma (PRP), which is easier to obtain and for which an empirical regenerative effect has been already described. To determine if PRP injection could replace the cutaneous regenerative effect of adipose-derived stem cells. This study was performed in 13 patients who were candidates for facelift. The patients underwent sampling of fat by liposuction from the abdomen and submitted to one of three protocols: injection of SVF-enriched fat or expanded adipose-derived stem cells or fat plus PRP in the preauricular areas. Fragments of skin were removed before and 3 months after treatment and analyzed by optical and electron microscopy. The use of fat plus PRP led to the presence of more pronounced inflammatory infiltrates and a greater vascular reactivity, increasing in vascular permeability and a certain reactivity of the nervous component. The addition of PRP did not improve the regenerative effect. The use of PRP did not have significant advantages in skin rejuvenation over the use of expanded adipose-derived stem cells or SVF-enriched fat. The effect of increased vascular reactivity may be useful in pathological situations in which an intense angiogenesis is desirable, such as tissular ischemia. © 2016 The American Society for Aesthetic Plastic Surgery, Inc. Reprints and permission: journals.permissions@oup.com.

Vascularized osseous graft for scaphoid

International Nuclear Information System (INIS)

Mendez Daza, Carlos Hernan; Mathoulin, Cristophe

2004-01-01

The most commonly used technique for treatment of pseudo-arthrosis of the scaphoid is osteo-synthesis with Kirschnet wires and cortical sponge grafts. Results reported by different teams using this procedure show no more than 90% osseous consolidation, especially in cases where vascularisation of the proximal fragment of the scaphoid is compromised. Here we present a series of ten cases of pseudo-arthrosis of the scaphoid, treated using a new surgical technique involving a vascularized osseous graft of the distal radius. Using this procedure we obtained 100% consolidation, with no complications either during the procedure or immediately post-operatively. Patients returned to work in week 15 on average. In 4 cases we observed discomfort in the area of the scar, which was successfully treated using local cortisone injection. The results obtained are very similar to those seen in the literature on the different techniques for vascularized osseous grafts for pseudo-arthrosis of the scaphoid

SELECTIVE AND NONSELECTIVE β-BLOCKERS IN PRIMARY OPEN ANGLE GLAUCOMA THERAPY – RESULTS OF COLOR DOPPLER SONOGRAPHY

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Vukoslava Maričić-Došen

2002-12-01

Full Text Available Background. Primary open angle glaucoma (POAG is a syndrome of progressive optic neuropathy characterized by optic nerve head excavation and visual field defects. Poor correlation between IOP and progression of glaucoma disease sets vascular mechanism in the centre of attention. By Color Doppler sonography, quantification of blood flow changes in vessels, which supply optic nerve head, is possible. We wanted to find out whether there are changes in the circulation of central retinal artery and posterior ciliary arteries in patients with primary open angle glaucoma treated with selective or nonselective β -blockers.Methods. 44 patients (88 eyes were divided into two groups: group 1: 22 patients (44 eyes treated with selective β -blockers (Betaxolol 0.5% and group 2: 22 patients (44 eyes treated with nonselective β -blockers (Timolol 0.5%. Vascular indices (RI, PI were measured in the central retinal artery and posterior ciliary arteries.Results. We found decreased blood flow and increased vascular indices in both groups of patients, statistically significant difference between group 1 and group 2: blood flow velocity was higher and vascular indices were lower in group 1 (Betaxolol 0.5% compared to group 2 (Timolol 0..5%.Conclusions. Selective β -blockers (calcium channel blockers act more vasoactively and neuroprotectively comparing to nonselective β -blockers.

Floral anatomy of Delphinieae (Ranunculaceae: comparing flower organization and vascular patterns

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Andrew V. Novikoff

2014-04-01

Full Text Available Species of the tribe Delphinieae have dorsoventralized flowers; their pentamerous calyx and reduced corolla are dorsally spurred and inner spurs are nectariferous. Based on this common floral scheme, Delphinieae species exhibit a wide diversity of floral structures and morphologies. We present here the first investigation of the floral anatomy in Delphinieae. The organization of the floral vascular system has been studied in species representative of the floral morphological diversity of Delphinieae: Aconitum lasiocarpum, Delphinium elatum, and Consolida regalis. The three species show a similar vascularization of the calyx and of the reproductive organs, but exhibit distinct anatomical features in the corolla where the nectaries are borne. The sepals and the stamens have a trilacunar three-traced and a unilacunar one-traced vascularization, respectively. Three free carpels in D. elatum and A. lasiocarpum are basically supplied by six vascular bundles – three independent dorsal bundles and three fused lateral bundles. In C. regalis the single carpel is supplied by three independent vascular bundles (one dorsal and two ventral. Staminodes are not vascularized. The basic type of petal vascularization is unilacunar one-traced, but in the case of C. regalis the derived bilacunar two-traced type has been observed. This latter state arose as a result of the fusion of the two dorsal petal primordia. The results of this first comparative study of the floral anatomy of Delphinieae are discussed with the recent phylogenetic, morphological, and evo-devo findings concerning the tribe.

Using biplanar fluoroscopy to guide radiopaque vascular injections: a new method for vascular imaging.

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Haley D O'Brien

Full Text Available Studying vascular anatomy, especially in the context of relationships with hard tissues, is of great interest to biologists. Vascular studies have provided significant insight into physiology, function, phylogenetic relationships, and evolutionary patterns. Injection of resin or latex into the vascular system has been a standard technique for decades. There has been a recent surge in popularity of more modern methods, especially radiopaque latex vascular injection followed by CT scanning and digital "dissection." This technique best displays both blood vessels and bone, and allows injections to be performed on cadaveric specimens. Vascular injection is risky, however, because it is not a standardizable technique, as each specimen is variable with regard to injection pressure and timing. Moreover, it is not possible to view the perfusion of injection medium throughout the vascular system of interest. Both data and rare specimens can therefore be lost due to poor or excessive perfusion. Here, we use biplanar video fluoroscopy as a technique to guide craniovascular radiopaque latex injection. Cadaveric domestic pigs (Sus scrofa domestica and white-tailed deer (Odocoileus virginianus were injected with radiopaque latex under guidance of fluoroscopy. This method was found to enable adjustments, in real-time, to the rate, location, and pressure at which latex is injected in order to avoid data and specimen loss. In addition to visualizing the injection process, this technique can be used to determine flow patterns, and has facilitated the development of consistent markers for complete perfusion.

Engineering the mechanical and biological properties of nanofibrous vascular grafts for in situ vascular tissue engineering.

Science.gov (United States)

Henry, Jeffrey J D; Yu, Jian; Wang, Aijun; Lee, Randall; Fang, Jun; Li, Song

2017-08-17

Synthetic small diameter vascular grafts have a high failure rate, and endothelialization is critical for preventing thrombosis and graft occlusion. A promising approach is in situ tissue engineering, whereby an acellular scaffold is implanted and provides stimulatory cues to guide the in situ remodeling into a functional blood vessel. An ideal scaffold should have sufficient binding sites for biomolecule immobilization and a mechanical property similar to native tissue. Here we developed a novel method to blend low molecular weight (LMW) elastic polymer during electrospinning process to increase conjugation sites and to improve the mechanical property of vascular grafts. LMW elastic polymer improved the elasticity of the scaffolds, and significantly increased the amount of heparin conjugated to the micro/nanofibrous scaffolds, which in turn increased the loading capacity of vascular endothelial growth factor (VEGF) and prolonged the release of VEGF. Vascular grafts were implanted into the carotid artery of rats to evaluate the in vivo performance. VEGF treatment significantly enhanced endothelium formation and the overall patency of vascular grafts. Heparin coating also increased cell infiltration into the electrospun grafts, thus increasing the production of collagen and elastin within the graft wall. This work demonstrates that LMW elastic polymer blending is an approach to engineer the mechanical and biological property of micro/nanofibrous vascular grafts for in situ vascular tissue engineering.

Episodic vertigo resulting from vascular risk factors, cervical spondylosis and head rotation: Two case reports

OpenAIRE

Owolabi, Mayowa O; Ogah, Okechukwu S; Ogunniyi, Adesola

2007-01-01

Background Vascular risk factors predispose to vertebrobasilar ischemia. Cervical osteophytes can impinge on the vertebral artery causing mechanical occlusion during head turning. Presentation with vertigo in such instances is a common finding. Case presentation A patient with obesity, hyperlipidemia, hypertension, cervical spondylosis, and vertigo triggered by head rotation is presented. She responded to antihypertensive and lipid-lowering drugs, vestibular sedative and application of cervic...

Biomarkers of drug-induced vascular injury

International Nuclear Information System (INIS)

Brott, D.; Gould, S.; Jones, H.; Schofield, J.; Prior, H.; Valentin, J.P; Bjurstrom, S.; Kenne, K.; Schuppe-Koistinen, I.; Katein, A.; Foster-Brown, L.; Betton, G.; Richardson, R.; Evans, G.; Louden, C.

2005-01-01

In pre-clinical safety studies, drug-induced vascular injury is an issue of concern because there are no obvious diagnostic markers for pre-clinical or clinical monitoring and there is an intellectual gap in our understanding of the pathogenesis of this lesion. While vasodilatation and increased shear stress appear to play a role, the exact mechanism(s) of injury to the primary targets, smooth muscle and endothelial cells are unknown. However, evaluation of novel markers for potential clinical monitoring with a mechanistic underpinning would add value in risk assessment and management. This mini review focuses on the progress to identify diagnostic markers of drug-induced vascular injury. Von Willebrand factor (vWF), released upon perturbation of endothelial cells, is transiently increased in plasma prior to morphological evidence of damage in dogs or rats treated with vascular toxicants. Therefore, vWF might be a predictive biomarker of vascular injury. However, vWF is not an appropriate biomarker of lesion progression or severity since levels return to baseline values when there is morphological evidence of injury. A potential mechanistically linked biomarker of vascular injury is caveolin-1. Expression of this protein, localized primarily to smooth muscle and endothelial cells, decreases with the onset of vascular damage. Since vascular injury involves multiple mediators and cell types, evaluation of a panel rather than a single biomarker may be more useful in monitoring early and severe progressive vascular injury

Pediatric interventional radiology: vascular interventions

International Nuclear Information System (INIS)

Kandasamy, Devasenathipathy; Gamanagatti, Shivanand; Gupta, Arun Kumar

2016-01-01

Pediatric interventional radiology (PIR) comprises a range of minimally invasive diagnostic and therapeutic procedures that are performed using image guidance. PIR has emerged as an essential adjunct to various surgical and medical conditions. Over the years, technology has undergone dramatic and continuous evolution, making this speciality grow. In this review, the authors will discuss various vascular interventional procedures undertaken in pediatric patients. It is challenging for the interventional radiologist to accomplish a successful interventional procedure. There are many vascular interventional radiology procedures which are being performed and have changed the way the diseases are managed. Some of the procedures are life saving and have become the treatment of choice in those patients. The future is indeed bright for the practice and practitioners of pediatric vascular and non-vascular interventions. As more and more of the procedures that are currently being performed in adults get gradually adapted for use in the pediatric population, it may be possible to perform safe and successful interventions in many of the pediatric vascular lesions that are otherwise being referred for surgery. (author)

Activation of Transient Receptor Potential Melastatin Subtype 8 Attenuates Cold-Induced Hypertension Through Ameliorating Vascular Mitochondrial Dysfunction.

Science.gov (United States)

Xiong, Shiqiang; Wang, Bin; Lin, Shaoyang; Zhang, Hexuan; Li, Yingsha; Wei, Xing; Cui, Yuanting; Wei, Xiao; Lu, Zongshi; Gao, Peng; Li, Li; Zhao, Zhigang; Liu, Daoyan; Zhu, Zhiming

2017-08-02

Environmental cold-induced hypertension is common, but how to treat cold-induced hypertension remains an obstacle. Transient receptor potential melastatin subtype 8 (TRPM8) is a mild cold-sensing nonselective cation channel that is activated by menthol. Little is known about the effect of TRPM8 activation by menthol on mitochondrial Ca 2+ homeostasis and the vascular function in cold-induced hypertension. Primary vascular smooth muscle cells from wild-type or Trpm8 -/- mice were cultured. In vitro, we confirmed that sarcoplasmic reticulum-resident TRPM8 participated in the regulation of cellular and mitochondrial Ca 2+ homeostasis in the vascular smooth muscle cells. TRPM8 activation by menthol antagonized angiotensin II induced mitochondrial respiratory dysfunction and excess reactive oxygen species generation by preserving pyruvate dehydrogenase activity, which hindered reactive oxygen species-triggered Ca 2+ influx and the activation of RhoA/Rho kinase pathway. In vivo, long-term noxious cold stimulation dramatically increased vasoconstriction and blood pressure. The activation of TRPM8 by dietary menthol inhibited vascular reactive oxygen species generation, vasoconstriction, and lowered blood pressure through attenuating excessive mitochondrial reactive oxygen species mediated the activation of RhoA/Rho kinase in a TRPM8-dependent manner. These effects of menthol were further validated in angiotensin II-induced hypertensive mice. Long-term dietary menthol treatment targeting and preserving mitochondrial function may represent a nonpharmaceutical measure for environmental noxious cold-induced hypertension. © 2017 The Authors. Published on behalf of the American Heart Association, Inc., by Wiley.

Rapid prototyping of biomimetic vascular phantoms for hyperspectral reflectance imaging

Science.gov (United States)

Ghassemi, Pejhman; Wang, Jianting; Melchiorri, Anthony J.; Ramella-Roman, Jessica C.; Mathews, Scott A.; Coburn, James C.; Sorg, Brian S.; Chen, Yu; Joshua Pfefer, T.

2015-12-01

The emerging technique of rapid prototyping with three-dimensional (3-D) printers provides a simple yet revolutionary method for fabricating objects with arbitrary geometry. The use of 3-D printing for generating morphologically biomimetic tissue phantoms based on medical images represents a potentially major advance over existing phantom approaches. Toward the goal of image-defined phantoms, we converted a segmented fundus image of the human retina into a matrix format and edited it to achieve a geometry suitable for printing. Phantoms with vessel-simulating channels were then printed using a photoreactive resin providing biologically relevant turbidity, as determined by spectrophotometry. The morphology of printed vessels was validated by x-ray microcomputed tomography. Channels were filled with hemoglobin (Hb) solutions undergoing desaturation, and phantoms were imaged with a near-infrared hyperspectral reflectance imaging system. Additionally, a phantom was printed incorporating two disjoint vascular networks at different depths, each filled with Hb solutions at different saturation levels. Light propagation effects noted during these measurements-including the influence of vessel density and depth on Hb concentration and saturation estimates, and the effect of wavelength on vessel visualization depth-were evaluated. Overall, our findings indicated that 3-D-printed biomimetic phantoms hold significant potential as realistic and practical tools for elucidating light-tissue interactions and characterizing biophotonic system performance.

Axon-glial disruption: the link between vascular disease and Alzheimer's disease?

Science.gov (United States)

Horsburgh, Karen; Reimer, Michell M; Holland, Philip; Chen, Guiquan; Scullion, Gillian; Fowler, Jill H

2011-08-01

Vascular risk factors play a critical role in the development of cognitive decline and AD (Alzheimer's disease), during aging, and often result in chronic cerebral hypoperfusion. The neurobiological link between hypoperfusion and cognitive decline is not yet defined, but is proposed to involve damage to the brain's white matter. In a newly developed mouse model, hypoperfusion, in isolation, produces a slowly developing and diffuse damage to myelinated axons, which is widespread in the brain, and is associated with a selective impairment in working memory. Cerebral hypoperfusion, an early event in AD, has also been shown to be associated with white matter damage and notably an accumulation of amyloid. The present review highlights some of the published data linking white matter disruption to aging and AD as a result of vascular dysfunction. A model is proposed by which chronic cerebral hypoperfusion, as a result of vascular factors, results in both the generation and accumulation of amyloid and injury to white matter integrity, resulting in cognitive impairment. The generation of amyloid and accumulation in the vasculature may act to perpetuate further vascular dysfunction and accelerate white matter pathology, and as a consequence grey matter pathology and cognitive decline.

Parallel inter channel interaction mechanisms

International Nuclear Information System (INIS)

Jovic, V.; Afgan, N.; Jovic, L.

1995-01-01

Parallel channels interactions are examined. For experimental researches of nonstationary regimes flow in three parallel vertical channels results of phenomenon analysis and mechanisms of parallel channel interaction for adiabatic condition of one-phase fluid and two-phase mixture flow are shown. (author)

The Complex Role of Store Operated Calcium Entry Pathways and Related Proteins in the Function of Cardiac, Skeletal and Vascular Smooth Muscle Cells

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Javier Avila-Medina

2018-03-01

Full Text Available Cardiac, skeletal, and smooth muscle cells shared the common feature of contraction in response to different stimuli. Agonist-induced muscle's contraction is triggered by a cytosolic free Ca2+ concentration increase due to a rapid Ca2+ release from intracellular stores and a transmembrane Ca2+ influx, mainly through L-type Ca2+ channels. Compelling evidences have demonstrated that Ca2+ might also enter through other cationic channels such as Store-Operated Ca2+ Channels (SOCCs, involved in several physiological functions and pathological conditions. The opening of SOCCs is regulated by the filling state of the intracellular Ca2+ store, the sarcoplasmic reticulum, which communicates to the plasma membrane channels through the Stromal Interaction Molecule 1/2 (STIM1/2 protein. In muscle cells, SOCCs can be mainly non-selective cation channels formed by Orai1 and other members of the Transient Receptor Potential-Canonical (TRPC channels family, as well as highly selective Ca2+ Release-Activated Ca2+ (CRAC channels, formed exclusively by subunits of Orai proteins likely organized in macromolecular complexes. This review summarizes the current knowledge of the complex role of Store Operated Calcium Entry (SOCE pathways and related proteins in the function of cardiac, skeletal, and vascular smooth muscle cells.

Initial evaluation of vascular ingrowth into superporous hydrogels.

Science.gov (United States)

Keskar, Vandana; Gandhi, Milind; Gemeinhart, Ernest J; Gemeinhart, Richard A

2009-08-01

There is a need for new materials and architectures for tissue engineering and regenerative medicine. Based upon our recent results developing novel scaffold architecture, we hypothesized that this new architecture would foster vascularization, a particular need for tissue engineering. We report on the potential of superporous hydrogel (SPH) scaffolds for in vivo cellular infiltration and vascularization. Poly(ethylene glycol) diacrylate (PEGDA) SPH scaffolds were implanted in the dorsum of severe combined immunodeficient (SCID) mice and harvested after 4 weeks of in vivo implantation. The SPHs were visibly red and vascularized, as apparent when compared to the non-porous hydrogel controls, which were macroscopically avascular. Host cell infiltration was observed throughout the SPHs. Blood cells and vascular structures, confirmed through staining for CD34 and smooth muscle alpha-actin, were observed throughout the scaffolds. This novel soft material may be utilized for cell transplantation, tissue engineering and in combination with cell therapies. The neovasularization and limited fibrotic response suggest that the architecture may be conducive to cell survival and rapid vessel development.

Local vascular adaptations after hybrid training in spinal cord-injured subjects.

NARCIS (Netherlands)

Thijssen, D.H.J.; Heesterbeek, P.J.C.; Kuppevelt, D. van; Duysens, J.E.J.; Hopman, M.T.E.

2005-01-01

PURPOSE: Studies investigating vascular adaptations in non-exercised areas during whole body exercise training show conflicting results. Individuals with spinal cord injury (SCI) provide a unique model to examine vascular adaptations in active tissue vs adjacent inactive areas. The purpose of this

Channel Planform Dynamics Monitoring and Channel Stability Assessment in Two Sediment-Rich Rivers in Taiwan

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Cheng-Wei Kuo

2017-01-01

Full Text Available Recurrent flood events induced by typhoons are powerful agents to modify channel morphology in Taiwan’s rivers. Frequent channel migrations reflect highly sensitive valley floors and increase the risk to infrastructure and residents along rivers. Therefore, monitoring channel planforms is essential for analyzing channel stability as well as improving river management. This study analyzed annual channel changes along two sediment-rich rivers, the Zhuoshui River and the Gaoping River, from 2008 to 2015 based on satellite images of FORMOSAT-2. Channel areas were digitized from mid-catchment to river mouth (~90 km. Channel stability for reaches was assessed through analyzing the changes of river indices including braid index, active channel width, and channel activity. In general, the valley width plays a key role in braided degree, active channel width, and channel activity. These indices increase as the valley width expands whereas the braid index decreases slightly close to the river mouth due to the change of river types. This downstream pattern in the Zhuoshui River was interrupted by hydraulic construction which resulted in limited changes downstream from the weir, due to the lack of water and sediment supply. A 200-year flood, Typhoon Morakot in 2009, induced significant changes in the two rivers. The highly active landscape in Taiwan results in very sensitive channels compared to other regions. An integrated Sensitivity Index was proposed for identifying unstable reaches, which could be a useful reference for river authorities when making priorities in river regulation strategy. This study shows that satellite image monitoring coupled with river indices analysis could be an effective tool to evaluate spatial and temporal changes in channel stability in highly dynamic river systems.

Benfotiamine Counteracts Smoking-Induced Vascular Dysfunction in Healthy Smokers

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Alin Stirban

2012-01-01

Full Text Available Background. Smoking induces endothelial dysfunction (ED mainly by exacerbating oxidative stress (OS and inflammation. Benfotiamine, a thiamine prodrug with high bioavailability, prevents nicotine-induced vascular dysfunction in rats. It remained unknown whether this effect also occurs in humans. Methods. Therefore, 20 healthy volunteers (mean age: 38 years were investigated twice, 7–10 days apart in a randomized, cross-over, and investigator-blinded design. Vascular function was assessed by flow-mediated vasodilatation (FMD of the brachial artery and by measurements of the soluble vascular cell adhesion molecule (sVCAM-1. Investigations were performed after an overnight fast as well as 20 minutes after one cigarette smoking. On another day, the same procedure was applied following a 3-day oral therapy with benfotiamine (1050 mg/day. Ten patients were randomized to start with smoking alone, and ten started with benfotiamine. Results. Results are expressed as (mean ± SEM. Smoking acutely induced a decrease in FMD by 50% (∗∗P<0.001 versus baseline an effect significantly reduced by benfotiamine treatment to 25%∗§ (∗P<0.05 versus baseline, §P<0.05 versus smoking alone. Smoking-induced elevation in sVCAM-1 was also prevented by benfotiamine. The endothelium-independent vasodilatation remained unaltered between days. Conclusion. In healthy volunteers, smoking blunts vascular function mirrored by a decrease in FMD and an increase in sVCAM-1. Short-term treatment with benfotiamine significantly reduces these effects, showing protective vascular properties.

Experience of vascular trauma in a tertiary care hospital

International Nuclear Information System (INIS)

Imtiaz, N.

2010-01-01

To highlight the presentation and management of various vascular injuries and their outcome. Thirty nine cases of vascular trauma were referred to vascular surgeon CMH Rawalpindi, in the above mentioned period. These cases were evaluated for mechanism of injury, age, gender and time of presentation. Out of these, only thirty cases were found suitable for surgical intervention. These thirty cases were evaluated for site of vascular injury, associated injuries, type of surgery performed and the outcome. Blunt trauma was the predominant cause of vascular injuries in our study 16/39 (41%). Fourteen cases (35.8%) had gun shot wounds. Only thirty patients (76.9 %) underwent various surgical procedures. Primary end to end anastomosis was possible in only 5/30 cases (16.6%) while reversed venous graft was used in 13/30 cases (43.3%). Wound infection occurred in 2/30(6.6%) cases out of which 1 case (3.3%) ultimately had an amputation. The time period between injury and surgical intervention ranged between 1 to 20 hours for most of the vascular injuries while delayed presentation in the form of traumatic arteriovenous fistula or pseudoaneurysm was between 48 hours to 3 months. There are reasonable numbers of vascular trauma cases being referred to a tertiary care hospital. Most of these cases reach us quite late due to unnecessary investigations, delayed referral and transportation. Early intervention and revascularization definitely reduces amputation and complication rate. All gunshot wounds not only require thorough surrounding soft tissue debridement but also liberal excision of traumatised vessel itself, resulting in interposition graft repair. (author)

Neuropsychiatric symptoms in Vascular Cognitive Impairment: A systematic review

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Chan Tiel

Full Text Available Neuropsychiatric symptoms or Behavioral and Psychological Symptoms of Dementia (BPSD are common and invariably appear at some point during the course of the disease, mediated both by cerebrovascular disease and neurodegenerative processes. Few studies have compared the profiles of BPSD in Vascular Cognitive Impairment (VCI of different subtypes (subcortical or cortical and clinical stages (Vascular Cognitive Impairment No Dementia [VaCIND] and Vascular Dementia [VaD].Objective:To review the BPSD associated with different subtypes and stages of VCI using the Neuropsychiatric Inventory (NPI.Methods:Medline, Scielo and Lilacs databases were searched for the period January 2000 to December 2014, with the key words: "BPSD AND Vascular Dementia, "NPI AND Vascular Dementia" and "NPI AND VCI. Qualitative analysis was performed on studies evaluating BPSD in VCI, using the Neuropsychiatric Inventory (NPI.Results:A total of 82 studies were retrieved of which 13 were eligible and thus included. Among the articles selected, 4 compared BPSD in Subcortical Vascular Dementia (SVaD versus Cortical-Subcortical Vascular Dementia (CSVaD, 3 involved comparisons between SVaD and VaCIND, 1 study analyzed differences between CSVaD and VaCIND, while 5 studies assessed BPSD in CSVaD. Subcortical and Cortical-Subcortical VaD were associated predominantly with Apathy and Depression. VaCIND may present fewer behavioral symptoms than VaD.Conclusion:The profile of BPSD differs for different stages of VCI. Determining the most prevalent BPSD in VCI subtypes might be helpful for improving early diagnosis and management of these symptoms.

Role of vascular physiology in hyperthermia

International Nuclear Information System (INIS)

Song, C.W.

1987-01-01

The rate of blood supply to tumors significantly varies depending on the tumor type, site of tumor growth, and the stage of tumor growth. Even in the same tumor, blood flow is rather heterogeneous. The peripheral area of the tumors where the tissue pressure is relatively low is usually well perfused. Blood flow in the tumors may or may not be greater than that in the adjacent normal tissues. The response of newly formed tumor blood vessels to external stress, such as heat, it different from that in the normal tissues. Blood flow in the experimental rodent tumors initially increases up to twofold of control when heated at relatively low temperatures but tends to decrease when heated at temperatures above 42 0 -43 0 C. On the contrary, blood flow in the skin and muscle of rodents increases up to 20-fold before vascular damage occurs on heating at 43 0 -45 0 C. It thus appears that the vascular beds in tumors are more vulnerable to heat than those in normal tissues. Because of the large increase in blood flow in normal tissue on heating, heat dissipation by blood flow is usually greater in normal tissues than that in tumors during heating. Consequently, the temperature of tumors may rise higher than that in normal tissues. Preferential heating of tumors, however, may not be achieved all the time because the relative blood perfusion in some tumors or in parts of a tumor remains greater than that in the surrounding normal tissues. The intrinsically acidic intratumor environment becomes further acidic on heating owing to an increase in the synthesis of acidic metabolites and retarded removal of them as a result of heat-induced vascular damage. The intratumor environment also becomes hypoxic as a result of retardation of blood flow and vascular damage after heating

Small GTP-Binding Protein Rac Is an Essential Mediator of Vascular Endothelial Growth Factor-Induced Endothelial Fenestrations and Vascular Permeability

DEFF Research Database (Denmark)

Eriksson, A.; Cao, R.; Tritsaris, K.

2003-01-01

fenestrated endothelium, a feature linked with increased vascular permeability. A cell-permeable Rac antagonist (TAT-RacN17) converted VEGF-induced, leaky vascular plexuses into well-defined vascular networks. In addition, this Rac mutant blocked formation of VEGF-induced endothelial fenestrations...... in mediation of VEGF-induced vascular permeability but less so in neovascularization. This may have conceptual implications for applying Rac antagonists in treatment and prevention of VEGF-induced vascular leakage and edema in connection with ischemic disorders....

Therapeutic Interference With Vascular Calcification—Lessons From Klotho-Hypomorphic Mice and Beyond

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Florian Lang

2018-05-01

Full Text Available Medial vascular calcification, a major pathophysiological process associated with cardiovascular disease and mortality, involves osteo-/chondrogenic transdifferentiation of vascular smooth muscle cells (VSMCs. In chronic kidney disease (CKD, osteo-/chondrogenic transdifferentiation of VSMCs and, thus, vascular calcification is mainly driven by hyperphosphatemia, resulting from impaired elimination of phosphate by the diseased kidneys. Hyperphosphatemia with subsequent vascular calcification is a hallmark of klotho-hypomorphic mice, which are characterized by rapid development of multiple age-related disorders and early death. In those animals, hyperphosphatemia results from unrestrained formation of 1,25(OH2D3 with subsequent retention of calcium and phosphate. Analysis of klotho-hypomorphic mice and mice with vitamin D3 overload uncovered several pathophysiological mechanisms participating in the orchestration of vascular calcification and several therapeutic opportunities to delay or even halt vascular calcification. The present brief review addresses the beneficial effects of bicarbonate, carbonic anhydrase inhibition, magnesium supplementation, mineralocorticoid receptor (MR blockage, and ammonium salts. The case is made that bicarbonate is mainly effective by decreasing intestinal phosphate absorption, and that carbonic anhydrase inhibition leads to metabolic acidosis, which counteracts calcium-phosphate precipitation and VSMC transdifferentiation. Magnesium supplementation, MR blockage and ammonium salts are mainly effective by interference with osteo-/chondrogenic signaling in VSMCs. It should be pointed out that the, by far, most efficient substances are ammonium salts, which may virtually prevent vascular calcification. Future research will probably uncover further therapeutic options and, most importantly, reveal whether these observations in mice can be translated into treatment of patients suffering from vascular calcification, such

Dividing Streamline Formation Channel Confluences by Physical Modeling

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Minarni Nur Trilita

2010-02-01

Full Text Available Confluence channels are often found in open channel network system and is the most important element. The incoming flow from the branch channel to the main cause various forms and cause vortex flow. Phenomenon can cause erosion of the side wall of the channel, the bed channel scour and sedimentation in the downstream confluence channel. To control these problems needed research into the current width of the branch channel. The incoming flow from the branch channel to the main channel flow bounded by a line distributors (dividing streamline. In this paper, the wide dividing streamline observed in the laboratory using a physical model of two open channels, a square that formed an angle of 30º. Observations were made with a variety of flow coming from each channel. The results obtained in the laboratory observation that the width of dividing streamline flow is influenced by the discharge ratio between the channel branch with the main channel. While the results of a comparison with previous studies showing that the observation in the laboratory is smaller than the results of previous research.

Complicação vascular de osteocondroma: relato de caso Vascular complication of osteochondroma: case report

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Fábio André Tornquist

2007-03-01

Full Text Available Osteocondromas ou exostoses são os tumores benignos mais comuns do tecido ósseo. Eles surgem durante o período de crescimento e, raramente, são responsáveis por complicações vasculares. No presente relato, reportamos um caso de paciente com osteocondroma no membro inferior e complicação vascular provocada pela compressão da artéria poplítea. O paciente apresentava queixas de dor em membro inferior direito quando foi investigado com angiografia e radiografia, que identificaram a lesão vascular e a tumoração óssea. Os tratamentos cirúrgicos simultâneos de ambas as lesões foram realizados com boa evolução pós-operatória.Osteochondromas or exostoses are the most common benign tumors of the bone. They occur during the growth period and are rarely responsible for vascular complications. We report a case of a patient with osteochondroma in the lower limb and vascular complication caused by compression of the popliteal artery. The patient complained of pain at the right lower limb during angiography and radiography screening, which identified the vascular lesion and the bone tumor. A simultaneous surgical treatment of both lesions was performed with good postoperative evolution.

MFAP4 Promotes Vascular Smooth Muscle Migration, Proliferation and Accelerates Neointima Formation

DEFF Research Database (Denmark)

Schlosser, Anders; Pilecki, Bartosz; Hemstra, Line E.

2016-01-01

in the vascular wall. The role of MFAP4 in vascular biology is unknown. We aimed to test the hypothesis that MFAP4 would enhance integrin-dependent VSMC activation. APPROACH AND RESULTS: We produced Mfap4-deficient (Mfap4(-/-)) mice and performed carotid artery ligation to explore the role of MFAP4 in vascular...... kinase and downstream kinases. In addition, we showed that MFAP4 promotes monocyte chemotaxis in integrin αVβ3-dependent manner. CONCLUSIONS: MFAP4 regulates integrin αVβ3-induced VSMC proliferation and migration, as well as monocyte chemotaxis, and accelerates neointimal hyperplasia after vascular...

Low-dimensional models of ‘Neuro-glio-vascular unit’ for describing neural dynamics under normal and energy-starved conditions

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Karishma eChhabria

2016-03-01

Full Text Available The motivation of developing simple minimal models for neuro-glio-vascular system arises from a recent modeling study elucidating the bidirectional information flow within the neuro-glio-vascular system having 89 dynamic equations (Chander and Chakravarthy 2012. While this was one of the first attempts at formulating a comprehensive model for neuro-glia-vascular system, it poses severe restrictions in scaling up to network levels. On the contrary, low dimensional models are convenient devices in simulating large networks that also provide an intuitive understanding of the complex interactions occurring within the neuro-glio-vascular system. The key idea underlying the proposed models is to describe the glio-vascular system as a lumped system which takes neural firing rate as input and returns an ‘energy’ variable (analogous to ATP as output. To this end we present two models: Biophysical neuro-energy (Model #1 with 5 variables, comprising of KATP channel activity governed by neuronal ATP dynamics and the Dynamic threshold (Model #2 with 3 variables depicting the dependence of neural firing threshold on the ATP dynamics. Both the models show different firing regimes such as continuous spiking, phasic and tonic bursting depending on the ATP production coefficient, εp and external current. We then demonstrate that in a network comprising of such energy-dependent neuron units, εp could modulate the Local field potential (LFP frequency and amplitude. Interestingly, low frequency LFP dominates under low εp conditions, which is thought to be reminiscent of seizure-like activity observed in epilepsy. The proposed ‘neuron-energy’ unit may be implemented in building models of neuro-glio-vascular networks to simulate data obtained from multimodal neuroimaging systems such as fNIRS-EEG and fMRI-EEG. Such models could also provide a theoretical basis for devising optimal neurorehabilitation strategies such as non-invasive brain stimulation for

Evaluation and percutaneous management of atherosclerotic peripheral vascular disease

International Nuclear Information System (INIS)

Widlus, D.M.; Osterman, F.A. Jr.

1989-01-01

Atherosclerotic peripheral vascular disease (PVD) of the lower extremities deprives a person of the ability to exercise to their satisfaction, later of the ability to perform the activities of their daily life, and finally of their legs themselves. Peripheral vascular disease has long been managed by the vascular surgeon utilizing endarterectomy and peripheral arterial bypass. Patient acceptance of nonsurgical, percutaneous procedures such as percutaneous transluminal balloon angioplasty (PTA) is high. Increased utilization of these procedures has led to improved techniques and adjuncts to therapy, as well as more critical review of long-term results. This article will review the evaluation and nonoperative management of PVD, with an emphasis on the newer modalities of management presently being investigated

Vascular responses to radiotherapy and androgendeprivation therapy in experimental prostate cancer

LENUS (Irish Health Repository)

2012-05-23

AbstractBackgroundRadiotherapy (RT) and androgen-deprivation therapy (ADT) are standard treatments for advanced prostate cancer (PC). Tumor vascularization is recognized as an important physiological feature likely to impact on both RT and ADT response, and this study therefore aimed to characterize the vascular responses to RT and ADT in experimental PC.MethodsUsing mice implanted with CWR22 PC xenografts, vascular responses to RT and ADT by castration were visualized in vivo by DCE MRI, before contrast-enhancement curves were analyzed both semi-quantitatively and by pharmacokinetic modeling. Extracted image parameters were correlated to the results from ex vivo quantitative fluorescent immunohistochemical analysis (qIHC) of tumor vascularization (9 F1), perfusion (Hoechst 33342), and hypoxia (pimonidazole), performed on tissue sections made from tumors excised directly after DCE MRI.ResultsCompared to untreated (Ctrl) tumors, an improved and highly functional vascularization was detected in androgen-deprived (AD) tumors, reflected by increases in DCE MRI parameters and by increased number of vessels (VN), vessel density ( VD), and vessel area fraction ( VF) from qIHC. Although total hypoxic fractions ( HF) did not change, estimated acute hypoxia scores ( AHS) – the proportion of hypoxia staining within 50 μm from perfusion staining – were increased in AD tumors compared to in Ctrl tumors. Five to six months after ADT renewed castration-resistant (CR) tumor growth appeared with an even further enhanced tumor vascularization. Compared to the large vascular changes induced by ADT, RT induced minor vascular changes. Correlating DCE MRI and qIHC parameters unveiled the semi-quantitative parameters area under curve ( AUC) from initial time-points to strongly correlate with VD and VF, whereas estimation of vessel size ( VS) by DCE MRI required pharmacokinetic modeling. HF was not correlated to any DCE MRI parameter, however, AHS may be estimated after

Vascular retraction driven by matrix softening

Science.gov (United States)

Valentine, Megan

We recently discovered we can directly apply physical forces and monitor the downstream responses in a living organism in real time through manipulation of the blood vessels of a marine organism called, Botryllus schlosseri. The extracellular matrix (ECM) plays a key role in regulating vascular growth and homeostasis in Botryllus,a basal chordate which has a large, transparent extracorporeal vascular network that can encompass areas >100 cm2. We have determined that lysyl oxidase 1 (LOX1), which is responsible for cross-linking collagen, is expressed in all vascular cells and is critically important for vascular maintenance. Inhibition of LOX1 activity in vivo by the addition of a specific inhibitor, ß-aminopropionitrile (BAPN), caused a rapid, global regression of the entire vascular bed, with some vessels regressing >10 mm within 16 hrs. In this talk, I will discuss the molecular and cellular origins of this systemic remodeling event, which hinges upon the ability of the vascular cells to sense and respond to mechanical signals, while introducing this exciting new model system for studies of biological physics and mechanobiology. Collaborators: Anthony DeTomaso, Delany Rodriguez, Aimal Khankhel (UCSB).

Vascular Response of the Segments Adjacent to the Proximal and Distal Edges of the ABSORB Everolimus-Eluting Bioresorbable Vascular Scaffold

DEFF Research Database (Denmark)

Gogas, Bill D; Serruys, Patrick W; Diletti, Roberto

2012-01-01

This study sought to investigate in vivo the vascular response at the proximal and distal edges of the second-generation ABSORB everolimus-eluting bioresorbable vascular scaffold (BVS).......This study sought to investigate in vivo the vascular response at the proximal and distal edges of the second-generation ABSORB everolimus-eluting bioresorbable vascular scaffold (BVS)....

Broad-range TRP channel inhibitors (2-APB, flufenamic acid, SKF-96365) affect differently contraction of resistance and conduit femoral arteries of rat

Czech Academy of Sciences Publication Activity Database

Bencze, Michal; Behuliak, Michal; Vavřínová, Anna; Zicha, Josef

2015-01-01

Roč. 765, Oct 15 (2015), s. 533-540 ISSN 0014-2999 R&D Projects: GA ČR(CZ) GAP304/12/0259 Institutional support: RVO:67985823 Keywords : femoral artery * TRP channel * 2-APB * flufenamic acid * SKF-96365 * vascular contraction Subject RIV: FA - Cardiovascular Diseases incl. Cardiotharic Surgery Impact factor: 2.730, year: 2015

A synergistic approach to the design, fabrication and evaluation of 3D printed micro and nano featured scaffolds for vascularized bone tissue repair

International Nuclear Information System (INIS)

Holmes, Benjamin; Bulusu, Kartik; Plesniak, Michael; Zhang, Lijie Grace

2016-01-01

3D bioprinting has begun to show great promise in advancing the development of functional tissue/organ replacements. However, to realize the true potential of 3D bioprinted tissues for clinical use requires the fabrication of an interconnected and effective vascular network. Solving this challenge is critical, as human tissue relies on an adequate network of blood vessels to transport oxygen, nutrients, other chemicals, biological factors and waste, in and out of the tissue. Here, we have successfully designed and printed a series of novel 3D bone scaffolds with both bone formation supporting structures and highly interconnected 3D microvascular mimicking channels, for efficient and enhanced osteogenic bone regeneration as well as vascular cell growth. Using a chemical functionalization process, we have conjugated our samples with nano hydroxyapatite (nHA), for the creation of novel micro and nano featured devices for vascularized bone growth. We evaluated our scaffolds with mechanical testing, hydrodynamic measurements and in vitro human mesenchymal stem cell (hMSC) adhesion (4 h), proliferation (1, 3 and 5 d) and osteogenic differentiation (1, 2 and 3 weeks). These tests confirmed bone-like physical properties and vascular-like flow profiles, as well as demonstrated enhanced hMSC adhesion, proliferation and osteogenic differentiation. Additional in vitro experiments with human umbilical vein endothelial cells also demonstrated improved vascular cell growth, migration and organization on micro-nano featured scaffolds. (paper)

A synergistic approach to the design, fabrication and evaluation of 3D printed micro and nano featured scaffolds for vascularized bone tissue repair

Science.gov (United States)

Holmes, Benjamin; Bulusu, Kartik; Plesniak, Michael; Zhang, Lijie Grace

2016-02-01

3D bioprinting has begun to show great promise in advancing the development of functional tissue/organ replacements. However, to realize the true potential of 3D bioprinted tissues for clinical use requires the fabrication of an interconnected and effective vascular network. Solving this challenge is critical, as human tissue relies on an adequate network of blood vessels to transport oxygen, nutrients, other chemicals, biological factors and waste, in and out of the tissue. Here, we have successfully designed and printed a series of novel 3D bone scaffolds with both bone formation supporting structures and highly interconnected 3D microvascular mimicking channels, for efficient and enhanced osteogenic bone regeneration as well as vascular cell growth. Using a chemical functionalization process, we have conjugated our samples with nano hydroxyapatite (nHA), for the creation of novel micro and nano featured devices for vascularized bone growth. We evaluated our scaffolds with mechanical testing, hydrodynamic measurements and in vitro human mesenchymal stem cell (hMSC) adhesion (4 h), proliferation (1, 3 and 5 d) and osteogenic differentiation (1, 2 and 3 weeks). These tests confirmed bone-like physical properties and vascular-like flow profiles, as well as demonstrated enhanced hMSC adhesion, proliferation and osteogenic differentiation. Additional in vitro experiments with human umbilical vein endothelial cells also demonstrated improved vascular cell growth, migration and organization on micro-nano featured scaffolds.

CIRSE Vascular Closure Device Registry

NARCIS (Netherlands)

Reekers, Jim A.; Müller-Hülsbeck, Stefan; Libicher, Martin; Atar, Eli; Trentmann, Jens; Goffette, Pierre; Borggrefe, Jan; Zeleňák, Kamil; Hooijboer, Pieter; Belli, Anna-Maria

2011-01-01

Vascular closure devices are routinely used after many vascular interventional radiology procedures. However, there have been no major multicenter studies to assess the safety and effectiveness of the routine use of closure devices in interventional radiology. The CIRSE registry of closure devices

The vascular secret of Klotho

DEFF Research Database (Denmark)

Lewin, Ewa; Olgaard, Klaus

2015-01-01

Klotho is an evolutionarily highly conserved protein related to longevity. Increasing evidence of a vascular protecting effect of the Klotho protein has emerged and might be important for future treatments of uremic vascular calcification. It is still disputed whether Klotho is locally expressed ...

Bone marrow mononuclear cell implantation in myocardial laser channels in the ischemic heart disease surgery. Long-term results

Science.gov (United States)

Chernyavskiy, Alexander; Fomichev, Alexey; Minin, Stanislav; Nikitin, Nikita

2017-10-01

Background: The problem of incomplete myocardial revascularization for diffuse and distal lesions of the myocardium is still relevant. We assessed the clinical and instrumental long-term results of autologous bone marrow cell (BMC) implantation in laser channels in ischemic heart disease with diffuse and distal coronary disease. 35 coronary heart disease (CHD) patients with diffuse and distal coronary disease during coronary artery bypass grafting (CABG) underwent BMC implantation in laser channels. The control group consisted of 29 patients. All patients in this group underwent only CABG. Clinical and instrumental assessment of the method's effect was carried out at two weeks, six months, and six years after surgery. Indirect revascularization showed more significant decreasing of the functional class (FC) New York Heart Association (NYHA), myocardial perfusion and contractility improvement. Autologous BMC implantation in laser channels is an effective method of CHD surgical treatment if it is impossible to perform direct myocardial revascularization. The indirect revascularization effect is formed in the first six months after surgery and remains at the same level for six years.

Obesity and risk of vascular disease: importance of endothelium-dependent vasoconstriction.

Science.gov (United States)

Barton, Matthias; Baretella, Oliver; Meyer, Matthias R

2012-02-01

Obesity has become a serious global health issue affecting both adults and children. Recent devolopments in world demographics and declining health status of the world's population indicate that the prevalence of obesity will continue to increase in the next decades. As a disease, obesity has deleterious effects on metabolic homeostasis, and affects numerous organ systems including heart, kidney and the vascular system. Thus, obesity is now regarded as an independent risk factor for atherosclerosis-related diseases such as coronary artery disease, myocardial infarction and stroke. In the arterial system, endothelial cells are both the source and target of factors contributing to atherosclerosis. Endothelial vasoactive factors regulate vascular homeostasis under physiological conditions and maintain basal vascular tone. Obesity results in an imbalance between endothelium-derived vasoactive factors favouring vasoconstriction, cell growth and inflammatory activation. Abnormal regulation of these factors due to endothelial cell dysfunction is both a consequence and a cause of vascular disease processes. Finally, because of the similarities of the vascular pathomechanisms activated, obesity can be considered to cause accelerated, 'premature' vascular aging. Here, we will review some of the pathomechanisms involved in obesity-related activation of endothelium-dependent vasoconstriction, the clinical relevance of obesity-associated vascular risk, and therapeutic interventions using 'endothelial therapy' aiming at maintaining or restoring vascular endothelial health. This article is part of a themed section on Fat and Vascular Responsiveness. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2012.165.issue-3. © 2011 The Authors. British Journal of Pharmacology © 2011 The British Pharmacological Society.

A multifaceted approach to maximize erectile function and vascular health.

Science.gov (United States)

Meldrum, David R; Gambone, Joseph C; Morris, Marge A; Ignarro, Louis J

2010-12-01

To review the role of various factors influencing vascular nitric oxide (NO) and cyclic GMP, and consequently, erectile function and vascular health. Pertinent publications are reviewed. Daily moderate exercise stimulates vascular NO production. Maintenance of normal body weight and waist/hip ratio allows NO stimulation by insulin. Decreased intake of fat, sugar, and simple carbohydrates rapidly converted to sugar reduces the adverse effects of fatty acids and sugar on endothelial NO production. Omega-3 fatty acids stimulate endothelial NO release. Antioxidants boost NO production and prevent NO breakdown. Folic acid, calcium, vitamin C, and vitamin E support the biochemical pathways leading to NO release. Cessation of smoking and avoidance of excessive alcohol preserve normal endothelial function. Moderate use of alcohol and certain proprietary supplements may favorably influence erectile and vascular function. Treatment of any remaining testosterone deficit will both increase erectile function and reduce any associated metabolic syndrome. After production of NO and cyclic GMP are improved, use of phosphodiesterase-5 inhibitors should result in greater success in treating remaining erectile dysfunction. Recent studies have also suggested positive effects of phosphodiesterase-5 inhibitors on vascular function. A multifaceted approach will maximize both erectile function and vascular health. Copyright © 2010 American Society for Reproductive Medicine. Published by Elsevier Inc. All rights reserved.

Methane dynamics in Northern Wetlands: Significance of vascular plants

Energy Technology Data Exchange (ETDEWEB)

Joabsson, Anna

2001-09-01

The studies presented illustrate several different aspects of the impact of vascular plants on methane emissions from northern natural wetlands. The subject has been approached on different scales, ranging from the study of microbial substrates in the vicinity of a single plant root, to an attempt to extrapolate some of the results to the entire northern hemisphere north of 50 meridian. The main overall conclusions from the papers are that vascular plants affect net methane emissions 1) by offering an efficient route of transport to the atmosphere so that methane oxidation in oxic surface soils is avoided, and 2) by being sources of methanogenic substrate. The degree to which vascular wetland plants affect methane emissions seems to be dependent on species-specific differences in both the capacity to act as gas conduits and the exudation of labile carbon compounds to the soil. An intimate coupling between vascular plant production and methane emission was found in an Arctic tundra wetland, although other environmental variables (water table, temperature) also contributed significantly to the explained variation in methane exchange. Studies of vascular plant extidation of organic acids suggest that the available pool of methanogenic substrates is both qualitatively and quantitatively correlated to vascular plant production (photosynthetic rate). On global scales, vascular plant production as a single factor does not seem to be sufficient to explain the majority of variation in methane flux patterns. Based on comparable experiments at five different sites in the northwestern Eurasian and Greenlandic North, we suggest that mean seasonal soil temperature is the best predictor of methane exchange on broad spatial and temporal scales.

Ion Channel Trafficking: Control of Ion Channel Density as a Target for Arrhythmias?

Directory of Open Access Journals (Sweden)

Elise Balse

2017-10-01

Full Text Available The shape of the cardiac action potential (AP is determined by the contributions of numerous ion channels. Any dysfunction in the proper function or expression of these ion channels can result in a change in effective refractory period (ERP and lead to arrhythmia. The processes underlying the correct targeting of ion channels to the plasma membrane are complex, and have not been fully characterized in cardiac myocytes. Emerging evidence highlights ion channel trafficking as a potential causative factor in certain acquired and inherited arrhythmias, and therapies which target trafficking as opposed to pore block are starting to receive attention. In this review we present the current evidence for the mechanisms which underlie precise control of cardiac ion channel trafficking and targeting.

Inter-arm systolic blood pressure differences, relations with future vascular events and mortality in patients with and without manifest vascular disease.

Science.gov (United States)

Kranenburg, Guido; Spiering, Wilko; de Jong, Pim A; Kappelle, L Jaap; de Borst, Gert Jan; Cramer, Maarten J; Visseren, Frank L J; Aboyans, Victor; Westerink, Jan

2017-10-01

Inter-arm systolic blood pressure difference (SBPD) is an easily obtained patient characteristic which relates to vascular disease. We aimed to identify determinants of large inter-arm SBPD and to investigate the relation between inter-arm SBPD and vascular events in patients with and without manifest vascular disease. In a cohort of 7344 patients with manifest vascular disease or vascular risk factors alone enrolled in the Second Manifestations of ARTerial disease (SMART) study, single bilateral non-simultaneous blood pressure measurements were performed. Logistic and Cox regression was used to identify determinants of large inter-arm SBPD (≥15mmHg) and to investigate the relation between inter-arm SBPD and vascular events (composite of non-fatal myocardial infarction, stroke, and vascular mortality) and all-cause mortality. In all patients the median inter-arm SBPD was 7mmHg (IQR 3-11) and 1182 (16%) patients had inter-arm SBPD ≥15mmHg. Higher age, higher systolic blood pressure, diabetes mellitus, peripheral artery disease, carotid artery stenosis, higher carotid intima-media thickness, and lower ankle-brachial indices were related to large inter-arm SBPD (≥15mmHg). Each 5mmHg increase in inter-arm SBPD was related to a 12% higher risk of vascular events in patients without manifest vascular disease (HR 1.12; 95% CI 1.00-1.27), whereas no relation was apparent in patients with manifest vascular disease (HR 0.98; 95% CI 0.93-1.04, interaction p-value 0.036). Inter-arm SBPD was not related to all-cause mortality (HR 1.05; 95% CI 0.93-1.19). Inter-arm SBPD relates to a higher risk of vascular events in patients without manifest vascular disease, whereas this relation is not apparent in patients with manifest vascular disease. Copyright © 2017 Elsevier B.V. All rights reserved.

Adiposity, adipocytokines & microvesicles in the etiology of vascular disease

NARCIS (Netherlands)

Kanhai, D.A.N.I.S.

2013-01-01

Vascular disease, in this thesis the terms vascular and cardiovascular are used interchangeably, is the number 1 cause of death worldwide. In 2008, 30% of all mortality had a vascular origin. Vascular mortality rates after a first manifestation of vascular disease are decreasing in Western society,

Presymptomatic genetic analysis during pregnancy for vascular type Ehlers–Danlos syndrome

Directory of Open Access Journals (Sweden)

Naing BT

2014-06-01

Full Text Available Banyar Than Naing,1 Atsushi Watanabe,1,2 Shinji Tanigaki,3 Masae Ono,4 Mitsutoshi Iwashita,3 Takashi Shimada1,21Department of Biochemistry and Molecular Biology, Nippon Medical School, Tokyo, Japan; 2Division of Clinical Genetics, Nippon Medical School Hospital, Tokyo, Japan; 3Department of Obstetrics and Gynecology, Kyorin University School of Medicine, Tokyo, Japan; 4Department of Pediatrics, Kyorin University School of Medicine, Tokyo, JapanAbstract: The vascular type of Ehlers–Danlos syndrome (EDS, EDS type IV (Online Mendelian Inheritance in Man [MIM] #130050 is characterized by thin, translucent skin, easy bruising, and arterial, intestinal, and/or uterine fragility during pregnancy, which may lead to sudden death. It is an autosomal dominant inherited disorder caused by type III procollagen gene (COL3A1: MIM #120180 mutations. Approximately 50% of the COL3A1 mutations are inherited from an affected parent, and 50% are de novo mutations. Each child of an affected individual has a 50% chance of inheriting the mutation and developing the disorder. Pregnant women with vascular EDS are at an increased risk of uterine and arterial rupture during the peripartum period, with high maternal morbidity and mortality rates. We report the first case of an asymptomatic 35-year-old woman at a risk of complications of vascular EDS who underwent presymptomatic evaluation during pregnancy. The sequencing results of both her brother and mother had a one-base-pair deletion, resulting in Glutamate at position 730 changing to Lysine and causing a frame shift and premature termination codon at 61 amino acids from the mutation position (p. Glu730Lysfs*61 on exon 32 of COL3A1. This deletion caused frameshift, leading to a premature termination codon (TAG at 181 nucleotides downstream in exon 35, which could not be detected by previous total RNA (ribonucleic acid method. Thus, she was at risk of complications of vascular EDS, and diagnostic testing was employed

Ion channelling in diamond

International Nuclear Information System (INIS)

Derry, T.E.

1978-06-01

Diamond is one of the most extreme cases from a channelling point of view, having the smallest thermal vibration amplitude and the lowest atomic number of commonly-encountered crystals. These are the two parameters most important for determining channelling behaviour. It is of consiberable interest therefore to see how well the theories explaining and predicting the channeling properties of other substance, succeed with diamond. Natural diamond, although the best available form for these experiments, is rather variable in its physical properties. Part of the project was devoted to considering and solving the problem of obtaining reproducible results representative of the ideal crystal. Channelling studies were performed on several good crystals, using the Rutherford backscattering method. Critical angles for proton channelling were measured for incident energies from 0.6 to 4.5 MeV, in the three most open axes and three most open planes of the diamond structure, and for α-particle channelling at 0.7 and 1.0 MeV (He + ) in the same axes and planes. For 1.0 MeV protons, the crystal temperature was varied from 20 degrees Celsius to 700 degrees Celsius. The results are presented as curves of backscattered yield versus angle in the region of each axis or plane, and summarised in the form of tables and graphs. Generally the critical angles, axial minimum yields, and temperature dependence are well predicted by the accepted theories. The most valuable overall conclusion is that the mean thermal vibration amplitude of the atoms in a crytical determines the critical approach distance to the channel walls at which an ion can remain channelled, even when this distance is much smaller than the Thomas-Fermi screening distance of the atomic potential, as is the case in diamond. A brief study was made of the radiation damage caused by α-particle bombardment, via its effect on the channelling phenomenon. It was possible to hold damage down to negligible levels during the

The impact of various scaffold components on vascularized bone constructs.

Science.gov (United States)

Eweida, Ahmad; Schulte, Matthias; Frisch, Oliver; Kneser, Ulrich; Harhaus, Leila

2017-06-01

. Collagen matrix and a smaller particle size provided more favorable results in terms of vascularization and tissue formation than diluted fibrin and larger Nanobone particles. Copyright © 2017 European Association for Cranio-Maxillo-Facial Surgery. Published by Elsevier Ltd. All rights reserved.

Adventitial gene transfer of catalase attenuates angiotensin II-induced vascular remodeling.

Science.gov (United States)

Liu, Cun-Fei; Zhang, Jia; Shen, Kai; Gao, Ping-Jin; Wang, Hai-Ya; Jin, Xin; Meng, Chao; Fang, Ning-Yuan

2015-04-01

Vascular adventitia and adventitia‑derived reactive oxygen species (ROS) contribute to vascular remodeling following vascular injury. A previous ex vivo study in adventitial fibroblasts showed that catalase, one of most important anti‑oxide enzymes, was downregulated by angiotensin II (AngII). The aim of the present study was to investigate whether adventitial gene transfer of catalase affects AngII‑induced vascular remodeling in vivo. Adenoviruses co‑expressing catalase and enhanced green fluorescent protein (eGFP) or expressing eGFP only were applied to the adventitial surface of common carotid arteries of Sprague‑Dawley rats. Alzet minipumps administering AngII (0.75 mg/kg/day) were then implanted subcutaneously for 14 days. Systolic blood pressure and biological parameters of vascular remodeling were measured in each group. Adventitial fibroblasts were cultured and p38 mitogen‑activated protein kinase (MAPK) phosphorylation was measured using western blot analysis. The results showed that adventitial gene transfer of catalase had no effect on AngII‑induced systolic blood pressure elevation. However, catalase adenovirus transfection significantly inhibited AngII‑induced media hypertrophy compared with that of the control virus (Padventitial α‑smooth muscle actin expression. Furthermore, catalase transfection significantly inhibited the AngII‑induced increase in p38MAPK phosphorylation. In conclusion, the results of the present study demonstrated that adventitial gene transfer of catalase significantly attenuated AngII‑induced vascular remodeling in rats via inhibition of adventitial p38MAPK phosphorylation.

Vascular Trauma Operative Experience is Inadequate in General Surgery Programs.

Science.gov (United States)

Yan, Huan; Maximus, Steven; Koopmann, Matthew; Keeley, Jessica; Smith, Brian; Virgilio, Christian de; Kim, Dennis Y

2016-05-01

Vascular injuries may be challenging, particularly for surgeons who have not received formal vascular surgery fellowship training. Lack of experience and improper technique can result in significant complications. The objective of this study was to examine changes in resident experience with operative vascular trauma over time. A retrospective review was performed using Accreditation Council for Graduate Medical Education (ACGME) case logs of general surgery residents graduating between 2004 and 2014 at 2 academic, university-affiliated institutions associated with level 1 trauma centers. The primary outcome was number of reported vascular trauma operations, stratified by year of graduation and institution. A total of 112 residents graduated in the study period with a median 7 (interquartile range 4.5-13.5) vascular trauma cases per resident. Fasciotomy and exposure and/or repair of peripheral vessels constituted the bulk of the operative volume. Linear regression showed no significant trend in cases with respect to year of graduation (P = 0.266). Residents from program A (n = 53) reported a significantly higher number of vascular trauma cases when compared with program B (n = 59): 12.0 vs. 5.0 cases, respectively (P < 0.001). Level 1 trauma center verification does not guarantee sufficient exposure to vascular trauma. The operative exposure in program B is reflective of the national average of 4.0 cases per resident as reported by the ACGME, and this trend is unlikely to change in the near future. Fellowship training may be critical for surgeons who plan to work in a trauma setting, particularly in areas lacking vascular surgeons. Copyright © 2016 Elsevier Inc. All rights reserved.

Extracellular Matrix Molecules Facilitating Vascular Biointegration

Directory of Open Access Journals (Sweden)

Martin K.C. Ng

2012-08-01

Full Text Available All vascular implants, including stents, heart valves and graft materials exhibit suboptimal biocompatibility that significantly reduces their clinical efficacy. A range of biomolecules in the subendothelial space have been shown to play critical roles in local regulation of thrombosis, endothelial growth and smooth muscle cell proliferation, making these attractive candidates for modulation of vascular device biointegration. However, classically used biomaterial coatings, such as fibronectin and laminin, modulate only one of these components; enhancing endothelial cell attachment, but also activating platelets and triggering thrombosis. This review examines a subset of extracellular matrix molecules that have demonstrated multi-faceted vascular compatibility and accordingly are promising candidates to improve the biointegration of vascular biomaterials.

B vitamins influence vascular cognitive impairment

Science.gov (United States)

As the number of elderly in the USA and globally continues to increase, age-related neurological disorders, such as Alzheimer's disease and vascular dementia, are a growing concern. The loss of memory, emotional changes, and impairments in general cognitive functioning frequently result in social is...

Vascular development in the vertebrate pancreas

Science.gov (United States)

Azizoglu, D. Berfin; Chong, Diana C.; Villasenor, Alethia; Magenheim, Judith; Barry, David M.; Lee, Simon; Marty-Santos, Leilani; Fu, Stephen; Dor, Yuval; Cleaver, Ondine

2016-01-01

The vertebrate pancreas is comprised of a highly branched tubular epithelium, which is intimately associated with an extensive and specialized vasculature. While we know a great deal about basic vascular anatomy of the adult pancreas, as well as islet capillaries, surprisingly little is known about the ontogeny of its blood vessels. Here, we analyze development of the pancreatic vasculature in the mouse embryo. We show that pancreatic epithelial branches intercalate with the fine capillary plexus of the surrounding pancreatic mesenchyme. Endothelial cells (ECs) within this mesenchyme are heterogeneous from the onset of organogenesis. Pancreatic arteries take shape before veins, in a manner analogous to early embryonic vessels. The main central artery forms during mid-gestation, as a result of vessel coalescence and remodeling of a vascular plexus. In addition, we show that vessels in the forming pancreas display a predictable architecture that is dependent on VEGF signaling. Over-expression of VEGF disrupts vascular patterning and arteriovenous differentiation within the developing pancreas. This study constitutes a first-time cellular and molecular characterization of pancreatic blood vessels, as they coordinately grow along with the pancreatic epithelium. PMID:27789228

Vascular development in the vertebrate pancreas.

Science.gov (United States)

Azizoglu, D Berfin; Chong, Diana C; Villasenor, Alethia; Magenheim, Judith; Barry, David M; Lee, Simon; Marty-Santos, Leilani; Fu, Stephen; Dor, Yuval; Cleaver, Ondine

2016-12-01

The vertebrate pancreas is comprised of a highly branched tubular epithelium, which is intimately associated with an extensive and specialized vasculature. While we know a great deal about basic vascular anatomy of the adult pancreas, as well as islet capillaries, surprisingly little is known about the ontogeny of its blood vessels. Here, we analyze development of the pancreatic vasculature in the mouse embryo. We show that pancreatic epithelial branches intercalate with the fine capillary plexus of the surrounding pancreatic mesenchyme. Endothelial cells (ECs) within this mesenchyme are heterogeneous from the onset of organogenesis. Pancreatic arteries take shape before veins, in a manner analogous to early embryonic vessels. The main central artery forms during mid-gestation, as a result of vessel coalescence and remodeling of a vascular plexus. In addition, we show that vessels in the forming pancreas display a predictable architecture that is dependent on VEGF signaling. Over-expression of VEGF disrupts vascular patterning and arteriovenous differentiation within the developing pancreas. This study constitutes a first-time in-depth cellular and molecular characterization of pancreatic blood vessels, as they coordinately grow along with the pancreatic epithelium. Copyright © 2016 Elsevier Inc. All rights reserved.

Channel Estimation in DCT-Based OFDM

Science.gov (United States)

Wang, Yulin; Zhang, Gengxin; Xie, Zhidong; Hu, Jing

2014-01-01

This paper derives the channel estimation of a discrete cosine transform- (DCT-) based orthogonal frequency-division multiplexing (OFDM) system over a frequency-selective multipath fading channel. Channel estimation has been proved to improve system throughput and performance by allowing for coherent demodulation. Pilot-aided methods are traditionally used to learn the channel response. Least square (LS) and mean square error estimators (MMSE) are investigated. We also study a compressed sensing (CS) based channel estimation, which takes the sparse property of wireless channel into account. Simulation results have shown that the CS based channel estimation is expected to have better performance than LS. However MMSE can achieve optimal performance because of prior knowledge of the channel statistic. PMID:24757439

Dynamic adaption of vascular morphology

DEFF Research Database (Denmark)

Okkels, Fridolin; Jacobsen, Jens Christian Brings

2012-01-01

The structure of vascular networks adapts continuously to meet changes in demand of the surrounding tissue. Most of the known vascular adaptation mechanisms are based on local reactions to local stimuli such as pressure and flow, which in turn reflects influence from the surrounding tissue. Here ...

Dynamics of nephron-vascular network

DEFF Research Database (Denmark)

Postnov, Dmitry; Postnov, D E; Marsh, D J

2012-01-01

The paper presents a modeling study of the spatial dynamics of a nephro-vascular network consisting of individual nephrons connected via a tree-like vascular branching structure. We focus on the effects of nonlinear mechanisms that are responsible for the formation of synchronous patterns in order...

Diagnostic criteria for vascular dementia

NARCIS (Netherlands)

Scheltens, P.; Hijdra, A. H.

1998-01-01

The term vascular dementia implies the presence of a clinical syndrome (dementia) caused by, or at least assumed to be caused by, a specific disorder (cerebrovascular disease). In this review, the various sets of criteria used to define vascular dementia are outlined. The various sets of criteria

A cross-site vascular radiology on-call service: the Manchester experience

International Nuclear Information System (INIS)

Ashleigh, R.J.; Butterfield, J.S.; Asquith, J.; Chalmers, N.; Murphy, G.

2005-01-01

AIM: A cross-site vascular radiology on-call service was established 5 years ago to cover two vascular centres in Manchester. We aimed to review the service. MATERIALS AND METHODS: A prospective audit of out-of hours referrals and procedures over a three month period (March-May 2003) was undertaken. RESULTS: There were 52 incidents in 49 patients (mean 4 calls per week). Nine involved telephone advice only, the remainder (82%) required a procedure. Angiography was performed on 88% of patients and therapeutic radiological intervention on 50%. 71% of calls occurred at a weekend. 50% of the calls were from vascular surgery and 50% from other sources. The consultant vascular radiologist was present for 93% of procedures. CONCLUSIONS: The workload suggests that a vascular radiology on call service is justified in Manchester. There have been no major problems with its implementation and operation. This is a consultant led service, with very few cases being devolved to a specialist registrar (SpR)

Agmatine suppresses peripheral sympathetic tone by inhibiting N-type Ca(2+) channel activity via imidazoline I2 receptor activation.

Science.gov (United States)

Kim, Young-Hwan; Jeong, Ji-Hyun; Ahn, Duck-Sun; Chung, Seungsoo

2016-08-26

Agmatine, a putative endogenous ligand of imidazoline receptors, suppresses cardiovascular function by inhibiting peripheral sympathetic tone. However, the molecular identity of imidazoline receptor subtypes and its cellular mechanism underlying the agmatine-induced sympathetic suppression remains unknown. Meanwhile, N-type Ca(2+) channels are important for the regulation of NA release in the peripheral sympathetic nervous system. Therefore, it is possible that agmatine suppresses NA release in peripheral sympathetic nerve terminals by inhibiting Ca(2+) influx through N-type Ca(2+) channels. We tested this hypothesis by investigating agmatine effect on electrical field stimulation (EFS)-evoked contraction and NA release in endothelium-denuded rat superior mesenteric arterial strips. We also investigated the effect of agmatine on the N-type Ca(2+) current in superior cervical ganglion (SCG) neurons in rats. Our study demonstrates that agmatine suppresses peripheral sympathetic outflow via the imidazoline I2 receptor in rat mesenteric arteries. In addition, the agmatine-induced suppression of peripheral vascular sympathetic tone is mediated by modulating voltage-dependent N-type Ca(2+) channels in sympathetic nerve terminals. These results suggest a potential cellular mechanism for the agmatine-induced suppression of peripheral sympathetic tone. Furthermore, they provide basic and theoretical information regarding the development of new agents to treat hypertension. Copyright © 2016 Elsevier Inc. All rights reserved.

On the Capacity of the Dirty Paper Channel with Fast Fading and Discrete Channel States

OpenAIRE

Rini, Stefano; Shitz, Shlomo Shamai

2016-01-01

The "writing dirty paper" capacity result crucially dependents on the perfect channel knowledge at the transmitter as the presence of even a small uncertainty in the channel realization gravely hampers the ability of the transmitter to pre-code its transmission against the channel state. This is particularly disappointing as it implies that interference pre-coding in practical systems is effective only when the channel estimates at the users have very high precision, a condition which is gene...

Quantum communication under channel uncertainty

International Nuclear Information System (INIS)

Noetzel, Janis Christian Gregor

2012-01-01

This work contains results concerning transmission of entanglement and subspaces as well as generation of entanglement in the limit of arbitrary many uses of compound- and arbitrarily varying quantum channels (CQC, AVQC). In both cases, the channel is described by a set of memoryless channels. Only forward communication between one sender and one receiver is allowed. A code is said to be ''good'' only, if it is ''good'' for every channel out of the set. Both settings describe a scenario, in which sender and receiver have only limited channel knowledge. For different amounts of information about the channel available to sender or receiver, coding theorems are proven for the CQC. For the AVQC, both deterministic and randomised coding schemes are considered. Coding theorems are proven, as well as a quantum analogue of the Ahlswede-dichotomy. The connection to zero-error capacities of stationary memoryless quantum channels is investigated. The notion of symmetrisability is defined and used for both classes of channels.

Scale-adaptive surface modeling of vascular structures

Directory of Open Access Journals (Sweden)

Ma Xin

2010-11-01

Full Text Available Abstract Background The effective geometric modeling of vascular structures is crucial for diagnosis, therapy planning and medical education. These applications require good balance with respect to surface smoothness, surface accuracy, triangle quality and surface size. Methods Our method first extracts the vascular boundary voxels from the segmentation result, and utilizes these voxels to build a three-dimensional (3D point cloud whose normal vectors are estimated via covariance analysis. Then a 3D implicit indicator function is computed from the oriented 3D point cloud by solving a Poisson equation. Finally the vessel surface is generated by a proposed adaptive polygonization algorithm for explicit 3D visualization. Results Experiments carried out on several typical vascular structures demonstrate that the presented method yields both a smooth morphologically correct and a topologically preserved two-manifold surface, which is scale-adaptive to the local curvature of the surface. Furthermore, the presented method produces fewer and better-shaped triangles with satisfactory surface quality and accuracy. Conclusions Compared to other state-of-the-art approaches, our method reaches good balance in terms of smoothness, accuracy, triangle quality and surface size. The vessel surfaces produced by our method are suitable for applications such as computational fluid dynamics simulations and real-time virtual interventional surgery.

Information geometry of Gaussian channels

International Nuclear Information System (INIS)

Monras, Alex; Illuminati, Fabrizio

2010-01-01

We define a local Riemannian metric tensor in the manifold of Gaussian channels and the distance that it induces. We adopt an information-geometric approach and define a metric derived from the Bures-Fisher metric for quantum states. The resulting metric inherits several desirable properties from the Bures-Fisher metric and is operationally motivated by distinguishability considerations: It serves as an upper bound to the attainable quantum Fisher information for the channel parameters using Gaussian states, under generic constraints on the physically available resources. Our approach naturally includes the use of entangled Gaussian probe states. We prove that the metric enjoys some desirable properties like stability and covariance. As a by-product, we also obtain some general results in Gaussian channel estimation that are the continuous-variable analogs of previously known results in finite dimensions. We prove that optimal probe states are always pure and bounded in the number of ancillary modes, even in the presence of constraints on the reduced state input in the channel. This has experimental and computational implications. It limits the complexity of optimal experimental setups for channel estimation and reduces the computational requirements for the evaluation of the metric: Indeed, we construct a converging algorithm for its computation. We provide explicit formulas for computing the multiparametric quantum Fisher information for dissipative channels probed with arbitrary Gaussian states and provide the optimal observables for the estimation of the channel parameters (e.g., bath couplings, squeezing, and temperature).

Progenitor cells in pulmonary vascular remodeling

Science.gov (United States)

Yeager, Michael E.; Frid, Maria G.; Stenmark, Kurt R.

2011-01-01

Pulmonary hypertension is characterized by cellular and structural changes in the walls of pulmonary arteries. Intimal thickening and fibrosis, medial hypertrophy and fibroproliferative changes in the adventitia are commonly observed, as is the extension of smooth muscle into the previously non-muscularized vessels. A majority of these changes are associated with the enhanced presence of α-SM-actin+ cells and inflammatory cells. Atypical abundances of functionally distinct endothelial cells, particularly in the intima (plexiform lesions), and also in the perivascular regions, are also described. At present, neither the origin(s) of these cells nor the molecular mechanisms responsible for their accumulation, in any of the three compartments of the vessel wall, have been fully elucidated. The possibility that they arise from either resident vascular progenitors or bone marrow–derived progenitor cells is now well established. Resident vascular progenitor cells have been demonstrated to exist within the vessel wall, and in response to certain stimuli, to expand and express myofibroblastic, endothelial or even hematopoietic markers. Bone marrow–derived or circulating progenitor cells have also been shown to be recruited to sites of vascular injury and to assume both endothelial and SM-like phenotypes. Here, we review the data supporting the contributory role of vascular progenitors (including endothelial progenitor cells, smooth muscle progenitor cells, pericytes, and fibrocytes) in vascular remodeling. A more complete understanding of the processes by which progenitor cells modulate pulmonary vascular remodeling will undoubtedly herald a renaissance of therapies extending beyond the control of vascular tonicity and reduction of pulmonary artery pressure. PMID:22034593

Rectal and splenic vascular malformation in klippel trenaunay weber syndrome: A case report

Energy Technology Data Exchange (ETDEWEB)

Kim, Ha Youn; Chang, Yun Woo; Lee, Dong Hwan [Soonchunhyang Univ. Hospital, Seoul (Korea, Republic of)

2012-10-15

Klippel Trenaunay Weber syndrome (KTWS) is a rare congenital disorder, characterized by a cutaneous vascular nevus of the involved extremity, vascular malformations, bone and soft tissue hypertrophy of the extremity. We present the case of an 18 year old female patient with KTWS, showing a marked rectosigmoid wall thickening and phlebolith, and also variable sized cystic masses in the spleen, as a result of vascular malformations.

Channelling and electromagnetic radiation of channelling particles

International Nuclear Information System (INIS)

Kalashnikov, N.

1983-01-01

A brief description is presented of the channelling of charged particles between atoms in the crystal lattice. The specificities are discussed of the transverse motion of channelling particles as are the origin and properties of quasi-characteristic radiation of channelling particles which accompany transfers from one band of permissible energies of the transverse motion of channelling particles to the other. (B.S.)

Vascular associated gene variants in patients with preeclampsia

DEFF Research Database (Denmark)

Lykke, Jacob A; Bare, Lance A; Olsen, Jørn

2012-01-01

Preeclampsia has been linked to subsequent vascular disease with many shared predisposing factors. We investigated the association between severe preeclampsia, and its subtypes, and specific vascular-related polymorphisms.......Preeclampsia has been linked to subsequent vascular disease with many shared predisposing factors. We investigated the association between severe preeclampsia, and its subtypes, and specific vascular-related polymorphisms....

Vascular phenotypes in nonvascular subtypes of the Ehlers-Danlos syndrome: a systematic review

Science.gov (United States)

D'hondt, Sanne; Van Damme, Tim; Malfait, Fransiska

2018-01-01

Purpose Within the spectrum of the Ehlers-Danlos syndromes (EDS), vascular complications are usually associated with the vascular subtype of EDS. Vascular complications are also observed in other EDS subtypes, but the reports are anecdotal and the information is dispersed. To better document the nature of vascular complications among “nonvascular” EDS subtypes, we performed a systematic review. Methods We queried three databases for English-language studies from inception until May 2017, documenting both phenotypes and genotypes of patients with nonvascular EDS subtypes. The outcome included the number and nature of vascular complications. Results A total of 112 papers were included and data were collected from 467 patients, of whom 77 presented with a vascular phenotype. Severe complications included mainly hematomas (53%), frequently reported in musculocontractural and classical-like EDS; intracranial hemorrhages (18%), with a high risk in dermatosparaxis EDS; and arterial dissections (16%), frequently reported in kyphoscoliotic and classical EDS. Other, more minor, vascular complications were reported in cardiac-valvular, arthrochalasia, spondylodysplastic, and periodontal EDS. Conclusion Potentially life-threatening vascular complications are a rare but important finding in several nonvascular EDS subtypes, highlighting a need for more systematic documentation. This review will help familiarize clinicians with the spectrum of vascular complications in EDS and guide follow-up and management. PMID:28981071

Vascularized bone transplant chimerism mediated by vascular endothelial growth factor.

Science.gov (United States)

Willems, Wouter F; Larsen, Mikko; Friedrich, Patricia F; Bishop, Allen T

2015-01-01

Vascular endothelial growth factor (VEGF) induces angiogenesis and osteogenesis in bone allotransplants. We aim to determine whether bone remodeling in VEGF-treated bone allotransplants results from repopulation with circulation-derived autogenous cells or survival of allogenic transplant-derived cells. Vascularized femoral bone transplants were transplanted from female Dark Agouti rats (DA;RT1(a) ) to male Piebald Viral Glaxo (PVG;RT1(c) ). Arteriovenous bundle implantation and short-term immunosuppression were used to maintain cellular viability. VEGF was encapsulated in biodegradable microspheres and delivered intramedullary in the experimental group (n = 22). In the control group (n = 22), no VEGF was delivered. Rats were sacrificed at 4 or 18 weeks. Laser capture microdissection of bone remodeling areas was performed at the inner and outer cortex. Sex-mismatched genes were quantified with reverse transcription-polymerase chain reaction to determine the amount of male cells to total cells, defined as the relative expression ratio (rER). At 4 weeks, rER was significantly higher at the inner cortex in VEGF-treated transplants as compared to untreated transplants (0.622 ± 0.225 vs. 0.362 ± 0.081, P = 0.043). At 4 weeks, the outer cortex in the control group had a significantly higher rER (P = 0.038), whereas in the VEGF group, the inner cortex had a higher rER (P = 0.015). Over time, in the outer cortex the rER significantly increased to 0.634 ± 0.106 at 18 weeks in VEGF-treated rats (P = 0.049). At 18 weeks, the rER was >0.5 at all cortical areas in both groups. These in vivo findings suggest a chemotactic effect of intramedullary applied VEGF on recipient-derived bone and could imply that more rapid angiogenesis of vascularized allotransplants can be established with microencapsulated VEGF. © 2014 Wiley Periodicals, Inc.

Automatic pickup of arrival time of channel wave based on multi-channel constraints

Science.gov (United States)

Wang, Bao-Li

2018-03-01

Accurately detecting the arrival time of a channel wave in a coal seam is very important for in-seam seismic data processing. The arrival time greatly affects the accuracy of the channel wave inversion and the computed tomography (CT) result. However, because the signal-to-noise ratio of in-seam seismic data is reduced by the long wavelength and strong frequency dispersion, accurately timing the arrival of channel waves is extremely difficult. For this purpose, we propose a method that automatically picks up the arrival time of channel waves based on multi-channel constraints. We first estimate the Jaccard similarity coefficient of two ray paths, then apply it as a weight coefficient for stacking the multichannel dispersion spectra. The reasonableness and effectiveness of the proposed method is verified in an actual data application. Most importantly, the method increases the degree of automation and the pickup precision of the channel-wave arrival time.

Selective block of KATP channels: why the anti-diabetic sulphonylureas and rosiglitazone have more in common than we thought

Science.gov (United States)

Dart, Caroline

2012-01-01

Rosiglitazone, the thiazolidinedione class anti-diabetic withdrawn from Europe in 2010 amid reports of adverse cardiovascular effects, is revealed by Yu et al. in this issue of the British Journal of Pharmacology to be a selective blocker of ATP-sensitive potassium (KATP) channels. This seems little cause for excitement given that the closure of pancreatic KATP channels is integral to insulin secretion; and sulphonylureas, which inhibit KATP channels, are widely used to treat type II diabetes. However, rosiglitazone, whose primary targets are nuclear transcription factors that regulate genes involved in lipid metabolism, blocks KATP channels by a novel mechanism different to that of the sulphonylureas and has a worrying preference for blood flow–regulating vascular KATP channels. Identification of a new molecule that modulates KATP channel gating will not only tell us more about how these complex metabolic sensors work but also raises questions as to whether rosiglitazone suppresses the cardiovascular system's ability to cope with metabolic stress – a claim that has dogged the sulphonylureas for many years. LINKED ARTICLE This article is a commentary on Yu et al., pp. 26–36 of this issue. To view this paper visit http://dx.doi.org/10.1111/j.1476-5381.2012.01934.x PMID:22506686

Nucleotide Excision DNA Repair is Associated with Age-Related Vascular Dysfunction

Science.gov (United States)

Durik, Matej; Kavousi, Maryam; van der Pluijm, Ingrid; Isaacs, Aaron; Cheng, Caroline; Verdonk, Koen; Loot, Annemarieke E.; Oeseburg, Hisko; Musterd-Bhaggoe, Usha; Leijten, Frank; van Veghel, Richard; de Vries, Rene; Rudez, Goran; Brandt, Renata; Ridwan, Yanto R.; van Deel, Elza D.; de Boer, Martine; Tempel, Dennie; Fleming, Ingrid; Mitchell, Gary F.; Verwoert, Germaine C.; Tarasov, Kirill V.; Uitterlinden, Andre G.; Hofman, Albert; Duckers, Henricus J.; van Duijn, Cornelia M.; Oostra, Ben A.; Witteman, Jacqueline C.M.; Duncker, Dirk J.; Danser, A.H. Jan; Hoeijmakers, Jan H.; Roks, Anton J.M.

2012-01-01

Background Vascular dysfunction in atherosclerosis and diabetes, as observed in the aging population of developed societies, is associated with vascular DNA damage and cell senescence. We hypothesized that cumulative DNA damage during aging contributes to vascular dysfunction. Methods and Results In mice with genomic instability due to the defective nucleotide excision repair genes ERCC1 and XPD (Ercc1d/− and XpdTTD mice), we explored age-dependent vascular function as compared to wild-type mice. Ercc1d/− mice showed increased vascular cell senescence, accelerated development of vasodilator dysfunction, increased vascular stiffness and elevated blood pressure at very young age. The vasodilator dysfunction was due to decreased endothelial eNOS levels as well as impaired smooth muscle cell function, which involved phosphodiesterase (PDE) activity. Similar to Ercc1d/− mice, age-related endothelium-dependent vasodilator dysfunction in XpdTTD animals was increased. To investigate the implications for human vascular disease, we explored associations between single nucleotide polymorphisms (SNPs) of selected nucleotide excision repair genes and arterial stiffness within the AortaGen Consortium, and found a significant association of a SNP (rs2029298) in the putative promoter region of DDB2 gene with carotid-femoral pulse wave velocity. Conclusions Mice with genomic instability recapitulate age-dependent vascular dysfunction as observed in animal models and in humans, but with an accelerated progression, as compared to wild type mice. In addition, we found associations between variations in human DNA repair genes and markers for vascular stiffness which is associated with aging. Our study supports the concept that genomic instability contributes importantly to the development of cardiovascular disease. PMID:22705887

On the secrecy capacity of the broadcast wiretap channel with imperfect channel state information

KAUST Repository

Hyadi, Amal

2014-12-01

In this paper, we consider secure broadcasting over fast fading channels. Assuming imperfect main channel state information (CSI) at the transmitter, we first provide an upper and a lower bounds on the ergodic secrecy capacity when a common message is broadcasted to multiple legitimate receivers in the presence of one eavesdropper. For this case, we show that the secrecy rate is limited by the legitimate receiver having, on average, the worst main channel link. Then, we present an expression for the achievable secrecy sum-rate when each legitimate receiver is interested in an independent message. The special cases of high SNR, perfect and no-main CSI are also analyzed. Numerical results are presented to illustrate the obtained results for the case of independent but not necessarily identically distributed Rayleigh fading channels.

A Perspective on the MIMO Wiretap Channel

KAUST Repository

Oggier, Frederique; Hassibi, Babak

2015-01-01

A wiretap channel is a communication channel between a transmitter Alice and a legitimate receiver Bob, in the presence of an eavesdropper Eve. The goal of communication is to achieve reliability between Alice and Bob, but also confidentiality despite Eve’s presence. Wiretap channels are declined in all kinds of flavors, depending on the underlying channels used by the three players: discrete memoryless channels, additive Gaussian noise channels, or fading channels, to name a few. In this survey, we focus on the case where the three players use multiple-antenna channels with Gaussian noise to communicate. After summarizing known results for multiple-input–multiple-output (MIMO) channels, both in terms of achievable reliable data rate (capacity) and code design, we introduce the MIMO wiretap channel. We then state the MIMO wiretap capacity, summarize the idea of the proof(s) behind this result, and comment on the insights given by the proofs on the physical meaning of the secrecy capacity. We finally discuss design criteria for MIMO wiretap codes.

A Perspective on the MIMO Wiretap Channel

KAUST Repository

Oggier, Frederique

2015-10-01

A wiretap channel is a communication channel between a transmitter Alice and a legitimate receiver Bob, in the presence of an eavesdropper Eve. The goal of communication is to achieve reliability between Alice and Bob, but also confidentiality despite Eve’s presence. Wiretap channels are declined in all kinds of flavors, depending on the underlying channels used by the three players: discrete memoryless channels, additive Gaussian noise channels, or fading channels, to name a few. In this survey, we focus on the case where the three players use multiple-antenna channels with Gaussian noise to communicate. After summarizing known results for multiple-input–multiple-output (MIMO) channels, both in terms of achievable reliable data rate (capacity) and code design, we introduce the MIMO wiretap channel. We then state the MIMO wiretap capacity, summarize the idea of the proof(s) behind this result, and comment on the insights given by the proofs on the physical meaning of the secrecy capacity. We finally discuss design criteria for MIMO wiretap codes.

Detection of TRPV4 channel current-like activity in Fawn Hooded hypertensive (FHH rat cerebral arterial muscle cells.

Directory of Open Access Journals (Sweden)

Debebe Gebremedhin

Full Text Available The transient receptor potential vallinoid type 4 (TRPV4 is a calcium entry channel known to modulate vascular function by mediating endothelium-dependent vasodilation. The present study investigated if isolated cerebral arterial myocytes of the Fawn Hooded hypertensive (FHH rat, known to display exaggerated KCa channel current activity and impaired myogenic tone, express TRPV4 channels at the transcript and protein level and exhibit TRPV4-like single-channel cationic current activity. Reverse transcription polymerase chain reaction (RT-PCR, Western blot, and immunostaining analysis detected the expression of mRNA transcript and translated protein of TRPV4 channel in FHH rat cerebral arterial myocytes. Patch clamp recording of single-channel current activity identified the presence of a single-channel cationic current with unitary conductance of ~85 pS and ~96 pS at hyperpolarizing and depolarizing potentials, respectively, that was inhibited by the TRPV4 channel antagonist RN 1734 or HC 067074 and activated by the potent TRPV4 channel agonist GSK1016790A. Application of negative pressure via the interior of the patch pipette increased the NPo of the TRPV4-like single-channel cationic current recorded in cell-attached patches at a patch potential of 60 mV that was inhibited by prior application of the TRPV4 channel antagonist RN 1734 or HC 067047. Treatment with the TRPV4 channel agonist GSK1016790A caused concentration-dependent increase in the NPo of KCa single-channel current recorded in cell-attached patches of cerebral arterial myocytes at a patch potential of 40 mV, which was not influenced by pretreatment with the voltage-gated L-type Ca2+ channel blocker nifedipine or the T-type Ca2+ channel blocker Ni2+. These findings demonstrate that FHH rat cerebral arterial myocytes express mRNA transcript and translated protein for TRPV4 channel and display TRPV4-like single-channel cationic current activity that was stretch-sensitive and

New Exact and Asymptotic Results of Dual-Branch MRC over Correlated Nakagami-m Fading Channels

KAUST Repository

Al-Quwaiee, Hessa

2015-05-01

We present in this paper a new performance analysis results of dual-branch maximal-ratio combining over correlated Nakagami-m fading channels with arbitrary fading parameter. In particular, we derive exact closed-form expressions of the outage probability, the average bit error rate, and the ergodic capacity in terms of the extended generalized bivariate Meijer G- function. Moreover, we also provide simple closed- form asymptotic expressions in the high signal-to- noise ratio regime of these three fundamental performance measures. © 2015 IEEE.

New Exact and Asymptotic Results of Dual-Branch MRC over Correlated Nakagami-m Fading Channels

KAUST Repository

Al-Quwaiee, Hessa; Alouini, Mohamed-Slim

2015-01-01

We present in this paper a new performance analysis results of dual-branch maximal-ratio combining over correlated Nakagami-m fading channels with arbitrary fading parameter. In particular, we derive exact closed-form expressions of the outage probability, the average bit error rate, and the ergodic capacity in terms of the extended generalized bivariate Meijer G- function. Moreover, we also provide simple closed- form asymptotic expressions in the high signal-to- noise ratio regime of these three fundamental performance measures. © 2015 IEEE.

hERG1 channels are overexpressed in glioblastoma multiforme and modulate VEGF secretion in glioblastoma cell lines

Science.gov (United States)

Masi, A; Becchetti, A; Restano-Cassulini, R; Polvani, S; Hofmann, G; Buccoliero, A M; Paglierani, M; Pollo, B; Taddei, G L; Gallina, P; Di Lorenzo, N; Franceschetti, S; Wanke, E; Arcangeli, A

2005-01-01

Recent studies have led to considerable advancement in our understanding of the molecular mechanisms that underlie the relentless cell growth and invasiveness of human gliomas. Partial understanding of these mechanisms has (1) improved the classification for gliomas, by identifying prognostic subgroups, and (2) pointed to novel potential therapeutic targets. Some classes of ion channels have turned out to be involved in the pathogenesis and malignancy of gliomas. We studied the expression and properties of K+ channels in primary cultures obtained from surgical specimens: human ether a gò-gò related (hERG)1 voltage-dependent K+ channels, which have been found to be overexpressed in various human cancers, and human ether a gò-gò-like 2 channels, that share many of hERG1's biophysical features. The expression pattern of these two channels was compared to that of the classical inward rectifying K+ channels, IRK, that are widely expressed in astrocytic cells and classically considered a marker of astrocytic differentiation. In our study, hERG1 was found to be specifically overexpressed in high-grade astrocytomas, that is, glioblastoma multiforme (GBM). In addition, we present evidence that, in GBM cell lines, hERG1 channel activity actively contributes to malignancy by promoting vascular endothelial growth factor secretion, thus stimulating the neoangiogenesis typical of high-grade gliomas. Our data provide important confirmation for studies proposing the hERG1 channel as a molecular marker of tumour progression and a possible target for novel anticancer therapies. PMID:16175187

Rapid prototyping of biomimetic vascular phantoms for hyperspectral reflectance imaging

Science.gov (United States)

Ghassemi, Pejhman; Wang, Jianting; Melchiorri, Anthony J.; Ramella-Roman, Jessica C.; Mathews, Scott A.; Coburn, James C.; Sorg, Brian S.; Chen, Yu; Joshua Pfefer, T.

2015-01-01

Abstract. The emerging technique of rapid prototyping with three-dimensional (3-D) printers provides a simple yet revolutionary method for fabricating objects with arbitrary geometry. The use of 3-D printing for generating morphologically biomimetic tissue phantoms based on medical images represents a potentially major advance over existing phantom approaches. Toward the goal of image-defined phantoms, we converted a segmented fundus image of the human retina into a matrix format and edited it to achieve a geometry suitable for printing. Phantoms with vessel-simulating channels were then printed using a photoreactive resin providing biologically relevant turbidity, as determined by spectrophotometry. The morphology of printed vessels was validated by x-ray microcomputed tomography. Channels were filled with hemoglobin (Hb) solutions undergoing desaturation, and phantoms were imaged with a near-infrared hyperspectral reflectance imaging system. Additionally, a phantom was printed incorporating two disjoint vascular networks at different depths, each filled with Hb solutions at different saturation levels. Light propagation effects noted during these measurements—including the influence of vessel density and depth on Hb concentration and saturation estimates, and the effect of wavelength on vessel visualization depth—were evaluated. Overall, our findings indicated that 3-D-printed biomimetic phantoms hold significant potential as realistic and practical tools for elucidating light–tissue interactions and characterizing biophotonic system performance. PMID:26662064

Plasma channels for electron beam transport

International Nuclear Information System (INIS)

Schneider, R.F.; Smith, J.R.; Moffatt, M.E.; Nguyen, K.T.; Uhm, H.S.

1988-01-01

In recent years, there has been much interest in transport of intense relativistic electron beams using plasma channels. These channels are formed by either: ionization of an organic gas by UV photoionization or electron impact ionization of a low pressure gas utilizing a low energy (typically several hundred volts) electron gun. The second method is discussed here. As their electron gun, the authors used a 12 volt lightbulb filament which is biased to -400 volts with respect to the grounded 15 cm diameter drift tube. The electrons emitted from the filament are confined by an axial magnetic field of --100 Gauss to create a plasma channel which is less than 1 cm in radius. The channel density has been determined with Langmuir probes and the resulting line densities were found to be 10 11 to 10 12 per cm. When a multi-kiloamp electron beam is injected onto this channel, the beam space charge will eject the plasma electrons leaving the ions behind to charge neutralize the electron beam, hence allowing the beam to propagate. In this work, the authors performed experimental studies on the dynamics of the plasma channel. These include Langmuir probe measurements of a steady state (DC) channel, as well as time-resolved Langmuir probe studies of pulsed channels. In addition they performed experimental studies of beam propagation in these plasma channels. Specifically, they observed the behavior of current transport in these channels. Detailed results of beam transport and channel studies are presented

Hydraulic efficiency and safety of vascular and non-vascular components in Pinus pinaster leaves.

Science.gov (United States)

Charra-Vaskou, Katline; Badel, Eric; Burlett, Régis; Cochard, Hervé; Delzon, Sylvain; Mayr, Stefan

2012-09-01

Leaves, the distal section of the soil-plant-atmosphere continuum, exhibit the lowest water potentials in a plant. In contrast to angiosperm leaves, knowledge of the hydraulic architecture of conifer needles is scant. We investigated the hydraulic efficiency and safety of Pinus pinaster needles, comparing different techniques. The xylem hydraulic conductivity (k(s)) and embolism vulnerability (P(50)) of both needle and stem were measured using the cavitron technique. The conductance and vulnerability of whole needles were measured via rehydration kinetics, and Cryo-SEM and 3D X-ray microtomographic observations were used as reference tools to validate physical measurements. The needle xylem of P. pinaster had lower hydraulic efficiency (k(s) = 2.0 × 10(-4) m(2) MPa(-1) s(-1)) and safety (P(50) = - 1.5 MPa) than stem xylem (k(s) = 7.7 × 10(-4) m(2) MPa(-1) s(-1); P(50) = - 3.6 to - 3.2 MPa). P(50) of whole needles (both extra-vascular and vascular pathways) was - 0.5 MPa, suggesting that non-vascular tissues were more vulnerable than the xylem. During dehydration to - 3.5 MPa, collapse and embolism in xylem tracheids, and gap formation in surrounding tissues were observed. However, a discrepancy in hydraulic and acoustic results appeared compared with visualizations, arguing for greater caution with these techniques when applied to needles. Our results indicate that the most distal parts of the water transport pathway are limiting for hydraulics of P. pinaster. Needle tissues exhibit a low hydraulic efficiency and low hydraulic safety, but may also act to buffer short-term water deficits, thus preventing xylem embolism.

Vascular Function at Baseline in the Hemodialysis Fistula Maturation Study

OpenAIRE

Dember, Laura M.; Imrey, Peter B.; Duess, Mai?Ann; Hamburg, Naomi M.; Larive, Brett; Radeva, Milena; Himmelfarb, Jonathan; Kraiss, Larry W.; Kusek, John W.; Roy?Chaudhury, Prabir; Terry, Christi M.; Vazquez, Miguel A.; Vongpatanasin, Wanpen; Beck, Gerald J.; Vita, Joseph A.

2016-01-01

Background End?stage renal disease is accompanied by functional and structural vascular abnormalities. The objective of this study was to characterize vascular function in a large cohort of patients with end?stage renal disease, using noninvasive physiological measurements, and to correlate function with demographic and clinical factors. Methods and Results We analyzed cross?sectional baseline data from the Hemodialysis Fistula Maturation Study, a multicenter prospective observational cohort ...

[Mechanism of losartan suppressing vascular calcification in rat aortic artery].

Science.gov (United States)

Shao, Juan; Wu, Panfeng; Wu, Jiliang; Li, Mincai

2016-08-01

Objective To investigate the effect of the angiotensin II receptor 1 (AT1R) blocker losartan on vascular calcification in rat aortic artery and explore the underlying mechanisms. Methods SD rats were divided randomly into control group, vascular calcification model group and treatment group. Vascular calcification models were made by subcutaneous injection of warfarin plus vitamin K1 for two weeks. Rats in the treatment group were subcutaneously injected with losartan (10 mg/kg) at the end of the first week and consecutively for one week. We observed the morphological changes by HE staining and the calcium deposition by Alizarin red staining in the artery vascular wall. The mRNA expressions of bone morphogenetic protein 2 (BMP2) and Runt-related transcription factor 2 (RUNX2) were analyzed by reverse transcription PCR. The BMP2 and RUNX2 protein expressions were determined by Western blotting. The apoptosis of smooth muscle cells (SMCs) were detected by TUNEL. The AT1R expression was tested by fluorescent immunohistochemistry. Results The aortic vascular calcification was induced by warfarin and vitamin K1. Compared with the vascular calcification model group, the mRNA and protein expressions of BMP2 and RUNX2 were significantly downregulated in the aorta in the losartan treatment group. Furthermore, the apoptosis of SMCs and the AT1R expression obviously decreased. Conclusion AT1R blocker losartan inhibits the apoptosis of SMCs and reduces AT1R expression; it downregulates the BMP2 and RUNX2 expressions in the vascular calcification process.

Impact of ICRP 117 recommendations in the operational protection of vascular radiology unit; Impacto de las recomendaciones de ICRP 117 en la proteccion operacional de una unidad de radiologia vascular

Energy Technology Data Exchange (ETDEWEB)

Gomez, Pablo Luis; Fernandez, Manuel; Verde, Jose Maria; Perez, Maria Esperanza; Gomez, Nuria, E-mail: pablog11@eresmas.com [Hospital Universitario de Salamanca (Spain). Servicio de Radio fisica y Proteccion Radiologica

2013-07-01

This paper lists and discusses the results obtained in the teams of the different specialties: traumatology, gastroenterology, hemodynamics, vascular radiology and neurosurgery at different care centres with various care portfolios and notable differences of technical resources. The results show a noticeable difference between the equipment used in gastroenterology, vascular radiology and hemodynamic reference services with other services and disciplines. Taking into account the recent 117 of ICRP publication it has been initiated a procedure for the estimation of dose of foot and ankle of the vascular radiologists and in crystalline. This paper shows the results obtained as well as the correlations between the mentioned area dose and values of dose of lapel, wrist, ankles and crystalline of the professionals.

Insulin resistance: vascular function and exercise

Directory of Open Access Journals (Sweden)

Moon-Hyon Hwang

2016-09-01

Full Text Available Insulin resistance associated with metabolic syndrome and Type 2 diabetes mellitus is an epidemic metabolic disorder, which increases the risk of cardiovascular complications. Impaired vascular endothelial function is an early marker for atherosclerosis, which causes cardiovascular complications. Both experimental and clinical studies indicate that endothelial dysfunction in vasculatures occurs with insulin resistance. The associated physiological mechanisms are not fully appreciated yet, however, it seems that augmented oxidative stress, a physiological imbalance between oxidants and antioxidants, in vascular cells is a possible mechanism involved in various vascular beds with insulin resistance and hyperglycemia. Regardless of the inclusion of resistance exercise, aerobic exercise seems to be beneficial for vascular endothelial function in both large conduit and small resistance vessels in both clinical and experimental studies with insulin resistance. In clinical cases, aerobic exercise over 8 weeks with higher intensity seems more beneficial than the cases with shorter duration and lower intensity. However, more studies are needed in the future to elucidate the physiological mechanisms by which vascular endothelial function is impaired in insulin resistance and improved with aerobic exercise.

Lifestyle and metabolic approaches to maximizing erectile and vascular health.

Science.gov (United States)

Meldrum, D R; Gambone, J C; Morris, M A; Esposito, K; Giugliano, D; Ignarro, L J

2012-01-01

Oxidative stress and inflammation, which disrupt nitric oxide (NO) production directly or by causing resistance to insulin, are central determinants of vascular diseases including ED. Decreased vascular NO has been linked to abdominal obesity, smoking and high intakes of fat and sugar, which all cause oxidative stress. Men with ED have decreased vascular NO and circulating and cellular antioxidants. Oxidative stress and inflammatory markers are increased in men with ED, and all increase with age. Exercise increases vascular NO, and more frequent erections are correlated with decreased ED, both in part due to stimulation of endothelial NO production by shear stress. Exercise and weight loss increase insulin sensitivity and endothelial NO production. Potent antioxidants or high doses of weaker antioxidants increase vascular NO and improve vascular and erectile function. Antioxidants may be particularly important in men with ED who smoke, are obese or have diabetes. Omega-3 fatty acids reduce inflammatory markers, decrease cardiac death and increase endothelial NO production, and are therefore critical for men with ED who are under age 60 years, and/or have diabetes, hypertension or coronary artery disease, who are at increased risk of serious or even fatal cardiac events. Phosphodiesterase inhibitors have recently been shown to improve antioxidant status and NO production and allow more frequent and sustained penile exercise. Some angiotensin II receptor blockers decrease oxidative stress and improve vascular and erectile function and are therefore preferred choices for lowering blood pressure in men with ED. Lifestyle modifications, including physical and penile-specific exercise, weight loss, omega-3 and folic acid supplements, reduced intakes of fat and sugar, and improved antioxidant status through diet and/or supplements should be integrated into any comprehensive approach to maximizing erectile function, resulting in greater overall success and patient

Postoperative radiographic evaluation of vascularized fibular grafts

International Nuclear Information System (INIS)

Manaster, B.J.; Coleman, D.A.; Bell, D.A.

1989-01-01

This paper reports on thirty-five patients with free vascularized fibular grafts examined postoperatively with plain radiography. Early graft incorporation is seen as a fuzziness of the cortex at the site of its insertion into the host bone. Causes of failure in grafting for bone defects include graft fracture, hardware failure, and infection. A high percentage of complications or at least delayed unions occurred when vascularized fibular grafts were used to fill defects in the lower extremity. Conversely, upper extremity defects bridged by vascularized grafts heal quickly and hypertrophy. Vascularized grafts placed in the femoral head and neck for a vascular necrosis incorporate early on their superior aspect. The osseous tunnel in which they are placed is normally wider than the graft and often becomes sclerotic; this appearance does not represent nonunion

Radiotherapy in combination with vascular-targeted therapies

International Nuclear Information System (INIS)

Ciric, Eva; Sersa, Gregor

2010-01-01

Given the critical role of tumor vasculature in tumor development, considerable efforts have been spent on developing therapeutic strategies targeting the tumor vascular network. A variety of agents have been developed, with two general approaches being pursued. Antiangiogenic agents (AAs) aim to interfere with the process of angiogenesis, preventing new tumor blood vessel formation. Vascular-disrupting agents (VDAs) target existing tumor vessels causing tumor ischemia and necrosis. Despite their great therapeutic potential, it has become clear that their greatest clinical utility may lie in combination with conventional anticancer therapies. Radiotherapy is a widely used treatment modality for cancer with its distinct therapeutic challenges. Thus, combining the two approaches seems reasonable. Strong biological rationale exist for combining vascular-targeted therapies with radiation. AAs and VDAs were shown to alter the tumor microenvironment in such a way as to enhance responses to radiation. The results of preclinical and early clinical studies have confirmed the therapeutic potential of this new treatment strategy in the clinical setting. However, concerns about increased normal tissue toxicity, have been raised

Sirtuins, Cell Senescence, and Vascular Aging.

Science.gov (United States)

Kida, Yujiro; Goligorsky, Michael S

2016-05-01

The sirtuins (SIRTs) constitute a class of proteins with nicotinamide adenine dinucleotide-dependent deacetylase or adenosine diphosphate-ribosyltransferase activity. Seven SIRT family members have been identified in mammals, from SIRT1, the best studied for its role in vascular aging, to SIRT7. SIRT1 and SIRT2 are localized in the nucleus and cytoplasm. SIRT3, SIRT4, and SIRT5 are mitochondrial, and SIRT6 and SIRT7 are nuclear. Extensive studies have clearly revealed that SIRT proteins regulate diverse cell functions and responses to stressors. Vascular aging involves the aging process (senescence) of endothelial and vascular smooth muscle cells. Two types of cell senescence have been identified: (1) replicative senescence with telomere attrition; and (2) stress-induced premature senescence without telomere involvement. Both types of senescence induce vascular cell growth arrest and loss of vascular homeostasis, and contribute to the initiation and progression of cardiovascular diseases. Previous mechanistic studies have revealed in detail that SIRT1, SIRT3, and SIRT6 show protective functions against vascular aging, and definite vascular function of other SIRTs is under investigation. Thus, direct SIRT modulation and nicotinamide adenine dinucleotide stimulation of SIRT are promising candidates for cardiovascular disease therapy. A small number of pilot studies have been conducted to assess SIRT modulation in humans. These clinical studies have not yet provided convincing evidence that SIRT proteins alleviate morbidity and mortality in patients with cardiovascular diseases. The outcomes of multiple ongoing clinical trials are awaited to define the efficacy of SIRT modulators and SIRT activators in cardiovascular diseases, along with the potential adverse effects of chronic SIRT modulation. Copyright © 2016 Canadian Cardiovascular Society. Published by Elsevier Inc. All rights reserved.

[Vascular aging, arterial hypertension and physical activity].

Science.gov (United States)

Schmidt-Trucksäss, A; Weisser, B

2011-11-01

The present review delineates the significance of intima-media-thickness, arterial stiffness and endothelial function for vascular aging. There is profound evidence for an increase in intima-media-thickness and vascular stiffness not only during healthy aging but induced also by cardiovascular risk factors. There is a central role of arterial hypertension for this progression in both structural factors. In addition, both parameters are strongly associated with cardiovascular risk. Endothelial function measured as postischemic flow-mediated vasodilatation is a functional parameter which is decreased both in healthy aging and by cardiovascular risk factors. Physical activity modifies the influence of aging and risk factors on endothelial function. A positive influence of endurance exercise on vascular stiffness and endothelial function has been demonstrated in numerous studies. In long-term studies, regular physical activity has been shown to reduce the progression of intima-media-thickness. Thus, arterial hypertension accelerates vascular aging, while physical activity has a positive influence on a variety of vascular parameters associated with vascular aging. © Georg Thieme Verlag KG Stuttgart · New York.

A Mathematical Model of Membrane Gas Separation with Energy Transfer by Molecules of Gas Flowing in a Channel to Molecules Penetrating this Channel from the Adjacent Channel

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Szwast Maciej

2015-06-01

Full Text Available The paper presents the mathematical modelling of selected isothermal separation processes of gaseous mixtures, taking place in plants using membranes, in particular nonporous polymer membranes. The modelling concerns membrane modules consisting of two channels - the feeding and the permeate channels. Different shapes of the channels cross-section were taken into account. Consideration was given to co-current and counter-current flows, for feeding and permeate streams, respectively, flowing together with the inert gas receiving permeate. In the proposed mathematical model it was considered that pressure of gas changes along the length of flow channels was the result of both - the drop of pressure connected with flow resistance, and energy transfer by molecules of gas flowing in a given channel to molecules which penetrate this channel from the adjacent channel. The literature on membrane technology takes into account only the drop of pressure connected with flow resistance. Consideration given to energy transfer by molecules of gas flowing in a given channel to molecules which penetrate this channel from the adjacent channel constitute the essential novelty in the current study. The paper also presents results of calculations obtained by means of a computer program which used equations of the derived model. Physicochemical data concerning separation of the CO2/CH4 mixture with He as the sweep gas and data concerning properties of the membrane made of PDMS were assumed for calculations.

Noninvasive diagnosis of allograft vascular disease after heart transplantation

Directory of Open Access Journals (Sweden)

Fernando Bacal

2001-01-01

Full Text Available OBJECTIVE: To determine the predictive values of noninvasive tests for the detection of allograft vascular disease. METHODS: We studied 39 patients with mean ages of 48±13 years and a follow-up period of 86±13 months. The diagnosis of allograft vascular disease was made by cine-coronary arteriography, and it was considered as positive if lesions existed that caused > or = 50% obstruction of the lumen. Patients underwent 24h Holter monitoring, thallium scintigraphy, a treadmill stress test, and dobutamine stress echocardiography. Sensitivity, specificity, and positive and negative predictive values were determined in percentages for each method, as compared with the cine-coronary arteriography results. RESULTS: Allograft vascular disease was found in 15 (38% patients. The Holter test showed 15.4% sensitivity, 95.5% specificity. For the treadmill stress test, sensitivity was 10%, specificity was 100%. When thallium scintigraphy was used, sensitivity was 40%, specificity 95.8%. On echocardiography with dobutamine, we found a 63.6% sensitivity, 91.3% specificity. When the dobutamine echocardiogram was associated with scintigraphy, sensitivity was 71.4%, specificity was 87%. CONCLUSION: In this group of patients, the combination of two noninvasive methods (dobutamine echocardiography and thallium scintigraphy may be a good alternative for the detection of allograft vascular disease in asymptomatic patients with normal ventricular function.

Taurine Supplementation Lowers Blood Pressure and Improves Vascular Function in Prehypertension: Randomized, Double-Blind, Placebo-Controlled Study.

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Sun, Qianqian; Wang, Bin; Li, Yingsha; Sun, Fang; Li, Peng; Xia, Weijie; Zhou, Xunmei; Li, Qiang; Wang, Xiaojing; Chen, Jing; Zeng, Xiangru; Zhao, Zhigang; He, Hongbo; Liu, Daoyan; Zhu, Zhiming

2016-03-01

Taurine, the most abundant, semiessential, sulfur-containing amino acid, is well known to lower blood pressure (BP) in hypertensive animal models. However, no rigorous clinical trial has validated whether this beneficial effect of taurine occurs in human hypertension or prehypertension, a key stage in the development of hypertension. In this randomized, double-blind, placebo-controlled study, we assessed the effects of taurine intervention on BP and vascular function in prehypertension. We randomly assigned 120 eligible prehypertensive individuals to receive either taurine supplementation (1.6 g per day) or a placebo for 12 weeks. Taurine supplementation significantly decreased the clinic and 24-hour ambulatory BPs, especially in those with high-normal BP. Mean clinic systolic BP reduction for taurine/placebo was 7.2/2.6 mm Hg, and diastolic BP was 4.7/1.3 mm Hg. Mean ambulatory systolic BP reduction for taurine/placebo was 3.8/0.3 mm Hg, and diastolic BP was 3.5/0.6 mm Hg. In addition, taurine supplementation significantly improved endothelium-dependent and endothelium-independent vasodilation and increased plasma H2S and taurine concentrations. Furthermore, changes in BP were negatively correlated with both the plasma H2S and taurine levels in taurine-treated prehypertensive individuals. To further elucidate the hypotensive mechanism, experimental studies were performed both in vivo and in vitro. The results showed that taurine treatment upregulated the expression of hydrogen sulfide-synthesizing enzymes and reduced agonist-induced vascular reactivity through the inhibition of transient receptor potential channel subtype 3-mediated calcium influx in human and mouse mesenteric arteries. In conclusion, the antihypertensive effect of chronic taurine supplementation shows promise in the treatment of prehypertension through improvement of vascular function. © 2016 American Heart Association, Inc.

Pulmonary vascular imaging

International Nuclear Information System (INIS)

Fedullo, P.F.; Shure, D.

1987-01-01

A wide range of pulmonary vascular imaging techniques are available for the diagnostic evaluation of patients with suspected pulmonary vascular disease. The characteristics of any ideal technique would include high sensitivity and specificity, safety, simplicity, and sequential applicability. To date, no single technique meets these ideal characteristics. Conventional pulmonary angiography remains the gold standard for the diagnosis of acute thromboembolic disease despite the introduction of newer techniques such as digital subtraction angiography and magnetic resonance imaging. Improved noninvasive lower extremity venous testing methods, particularly impedance plethysmography, and ventilation-perfusion scanning can play significant roles in the noninvasive diagnosis of acute pulmonary emboli when properly applied. Ventilation-perfusion scanning may also be useful as a screening test to differentiate possible primary pulmonary hypertension from chronic thromboembolic pulmonary hypertension. And, finally, angioscopy may be a useful adjunctive technique to detect chronic thromboembolic disease and determine operability. Optimal clinical decision-making, however, will continue to require the proper interpretation of adjunctive information obtained from the less-invasive techniques, applied with an understanding of the natural history of the various forms of pulmonary vascular disease and with a knowledge of the capabilities and shortcomings of the individual techniques

Vascular lumen formation.

Science.gov (United States)

Lammert, Eckhard; Axnick, Jennifer

2012-04-01

The vascular system developed early in evolution. It is required in large multicellular organisms for the transport of nutrients, oxygen, and waste products to and from tissues. The vascular system is composed of hollow tubes, which have a high level of complexity in vertebrates. Vasculogenesis describes the de novo formation of blood vessels, e.g., aorta formation in vertebrate embryogenesis. In contrast, angiogenesis is the formation of blood vessels from preexisting ones, e.g., sprouting of intersomitic blood vessels from the aorta. Importantly, the lumen of all blood vessels in vertebrates is lined and formed by endothelial cells. In both vasculogenesis and angiogenesis, lumen formation takes place in a cord of endothelial cells. It involves a complex molecular mechanism composed of endothelial cell repulsion at the cell-cell contacts within the endothelial cell cords, junctional rearrangement, and endothelial cell shape change. As the vascular system also participates in the course of many diseases, such as cancer, stroke, and myocardial infarction, it is important to understand and make use of the molecular mechanisms of blood vessel formation to better understand and manipulate the pathomechanisms involved.

Composite vascular grafts with high cell infiltration by co-electrospinning

International Nuclear Information System (INIS)

Tan, Zhikai; Wang, Hongjie; Gao, Xiangkai; Liu, Tong; Tan, Yongjun

2016-01-01

There is an increasing demand for functional small-diameter vascular grafts (diameter < 6 mm) to be used in clinical arterial replacement. An ideal vascular graft should have appropriate biomechanical properties and be biocompatible. Electrospinning has become a popular polymer processing technique for vascular tissue engineering, but the grafts fabricated by electrospinning often have relatively small pores and low porosity, which limit cell infiltration into scaffolds and hinder the regeneration and remodeling of grafts. In the present study, we aimed to develop an efficient method to prepare electrospun composite vascular grafts comprising natural and synthetic materials. We fabricated grafts made of polycaprolactone, gelatin, and polyvinyl alcohol (PVA) by co-electrospinning, and the scaffolds were further functionalized by immobilizing heparin on them. The PVA fibers degraded rapidly in vivo and generated electrospun scaffolds with high porosity, which significantly enhanced cell proliferation and infiltration. The mechanical properties of the grafts are suitable for use in artery replacement. Heparin functionalization of the grafts yielded a good antithrombogenic effect, which was demonstrated in platelet adhesion tests. Moreover, in vitro and in vivo results demonstrated that the heparin release from the grafts enhanced the growth of endothelial cells, which is important for the endothelium of implanted grafts. The results of this study indicate that our method is effective and controllable for the fabrication of vascular grafts that meet the clinical requirements for blood vessel transplantation. - Highlights: • This study indicate an effective method for the fabrication of vascular grafts that meet the clinical requirements. • Co-electrospinning were used to fabricate grafts made of polycaprolactone (PCL), gelatin (GT), and polyvinyl alcohol (PVA). • PVA was used to create large pores within the hybrid scaffolds, thereby enhancing cell infiltration

Composite vascular grafts with high cell infiltration by co-electrospinning

Energy Technology Data Exchange (ETDEWEB)

Tan, Zhikai, E-mail: tanzk@hnu.edu.cn; Wang, Hongjie; Gao, Xiangkai; Liu, Tong; Tan, Yongjun

2016-10-01

There is an increasing demand for functional small-diameter vascular grafts (diameter < 6 mm) to be used in clinical arterial replacement. An ideal vascular graft should have appropriate biomechanical properties and be biocompatible. Electrospinning has become a popular polymer processing technique for vascular tissue engineering, but the grafts fabricated by electrospinning often have relatively small pores and low porosity, which limit cell infiltration into scaffolds and hinder the regeneration and remodeling of grafts. In the present study, we aimed to develop an efficient method to prepare electrospun composite vascular grafts comprising natural and synthetic materials. We fabricated grafts made of polycaprolactone, gelatin, and polyvinyl alcohol (PVA) by co-electrospinning, and the scaffolds were further functionalized by immobilizing heparin on them. The PVA fibers degraded rapidly in vivo and generated electrospun scaffolds with high porosity, which significantly enhanced cell proliferation and infiltration. The mechanical properties of the grafts are suitable for use in artery replacement. Heparin functionalization of the grafts yielded a good antithrombogenic effect, which was demonstrated in platelet adhesion tests. Moreover, in vitro and in vivo results demonstrated that the heparin release from the grafts enhanced the growth of endothelial cells, which is important for the endothelium of implanted grafts. The results of this study indicate that our method is effective and controllable for the fabrication of vascular grafts that meet the clinical requirements for blood vessel transplantation. - Highlights: • This study indicate an effective method for the fabrication of vascular grafts that meet the clinical requirements. • Co-electrospinning were used to fabricate grafts made of polycaprolactone (PCL), gelatin (GT), and polyvinyl alcohol (PVA). • PVA was used to create large pores within the hybrid scaffolds, thereby enhancing cell infiltration

Effects of ethanol on voltage-sensitive Na-channels in cultured skeletal muscle: Up-regulation as a result of chronic treatment

International Nuclear Information System (INIS)

Brodie, C.; Sampson, S.R.

1990-01-01

The effects of acute and chronic treatment with ethanol were studied on the number and activity of tetrodotoxin-sensitive Na-channels in cultured rat skeletal muscle. The number of channels was determined by measurements of specific binding of [3H] saxitoxin (STX) in whole cell preparations. Measurements were also made of the frequency and rate of rise of spontaneously occurring action potentials, which are the physiologic expression of Na-channel density. Acute ethanol (37.5-150 mM), while causing depolarization of membrane potential and blockade of electrical activity, was without effect on specific STX binding. Neither methanol, acetaldehyde nor ethylene glycol had significant effects on these properties when given acutely in the same concentrations as ethanol. Chronic ethanol caused dose-related increases in STX binding and action potential properties with maximal levels being attained after 3 days of treatment at a concentration of 150 mM. On removal of ethanol from the culture medium all properties returned to control levels after 48 hr. Both increased external K+ and tetrodotoxin, which up-regulate Na-channels by reducing cytosolic Ca++, potentiated the ethanol-induced increase in Na-channel density. The increase in STX binding was not associated with changes in affinity of the binding sites for the ligand but was completely prevented by treatment with cycloheximide and actinomycin D. The results demonstrate that ethanol interacts with the cell membrane to induce synthesis of STX-binding sites

Low SNR capacity for MIMO Rician and Rayleigh-product fading channels with single co-channel interferer and noise

KAUST Repository

Zhong, Caijun

2010-09-01

This paper studies the ergodic capacity of multiple-input multiple-output (MIMO) systems with a single co-channel interferer in the low signal-to-noise-ratio (SNR) regime. Two MIMO models namely Rician and Rayleigh-product channels are investigated. Exact analytical expressions for the minimum energy per information bit, {Eb/N0min, and wideband slope, S0, are derived for both channels. Our results show that the minimum energy per information bit is the same for both channels while their wideband slopes differ significantly. Further, the impact of the numbers of transmit and receive antennas, the Rician K factor, the channel mean matrix and the interference-to-noise-ratio (INR) on the capacity, is addressed. Results indicate that interference degrades the capacity by increasing the required minimum energy per information bit and reducing the wideband slope. Simulation results validate our analytical results. © 2010 IEEE.

Localisation of SCN10A gene product Na(v)1.8 and novel pain-related ion channels in human heart.

Science.gov (United States)

Facer, Paul; Punjabi, Prakash P; Abrari, Andleeb; Kaba, Riyaz A; Severs, Nicholas J; Chambers, John; Kooner, Jaspal S; Anand, Praveen

2011-01-01

We have shown that the gene SCN10A encoding the sodium channel Na(v)1.8 is a susceptibility factor for heart block and serious ventricular arrhythmia. Since Na(v)1.8 is known to be present in nerve fibres that mediate pain, it may be related to both cardiac pain and dysrhythmia. The localisation of Na(v)1.8 and other key nociceptive ion channels, including Na(v)1.7, Na(v)1.9, capsaicin receptor TRPV1, and purinergic receptor P2X(3), have not been reported in human heart. The aim of this study was to determine the distribution of Na(v)1.8, related sodium and other sensory channels in human cardiac tissue, and correlate their density with sympathetic nerves, regenerating nerves (GAP-43), and vascularity. Human heart atrial appendage tissues (n = 13) were collected during surgery for valve disease. Tissues were investigated by immunohistology using specific antibodies to Na(v)1.8 and other markers. Na(v)1.8 immunoreactivity was detected in nerve fibres and fascicles in the myocardium, often closely associated with small capillaries. Na(v)1.8 nerve fibres per mm(2) correlated significantly with vascular markers. Na(v)1.8-immunoreactivity was present also in cardiomyocytes with a similar distribution pattern to that seen with connexins, the specialised gap junction proteins of myocardial intercalated discs. Na(v)1.5-immunoreactivity was detected in cardiomyocytes but not in nerve fibres. Na(v)1.7, Na(v)1.9, TRPV1, P2X(3)/P2X(2), and GAP43 positive nerve fibres were relatively sparse, whereas sympathetic innervation and connexin43 were abundant. We conclude that sodium channel Na(v)1.8 is present in sensory nerves and cardiomyocytes of human heart. Na(v)1.8 and other pain channels provide new targets for the understanding and treatment of cardiac pain and dysrhythmia.

Coexistence of pheochromocytoma with uncommon vascular lesions

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Sunil Kumar Kota

2012-01-01

Full Text Available Background: Pheochromocytoma/paragangliomas have been described to be associated with rare vascular abnormalities like renal artery stenosis. Coexistence of physiologically significant renal artery lesions is a compounding factor that alters management and prognosis of pheochromocytoma patients. Apart from individual case reports, data on such association in Indian population is not available. The aim of this study is to find the nature and prevalence of associated vascular abnormalities. Materials and Methods: From 1990 to 2010, a total of 50 patients were diagnosed with pheochromocytoma/paragangliomas. Hospital charts of these patients were reviewed retrospectively to identify those with unusual vascular abnormalities. Available literature was also reviewed. Results: Of the 50 patients with pheochromocytoma, 7 (14% had coexisting vascular lesions including renal artery stenosis in 4, aortoarteritis in 1, aortic aneurysm in 1 and inferior vena cava thrombosis in 1. Pheochromocytoma was adrenal in 42 and extra adrenal in 8. Laparoscopic adrenalectomy was done in the patients. One patient with renal artery stenosis due to intimal fibrosis was subjected to percutaneous balloon angioplasty; the other three improved after adrenalectomy and lysis of fibrous adhesive bands. The patient with aortoarteritos was treated with oral steroids. Inferior vena cava thrombosis was reversed with anticoagulants. The patient with abdominal aortic aneurysm was advised for annual follow-up on account of its size of 4.5 cm and asymptomatic presentation. Conclusion: There are multiple mechanisms that can lead to renal artery stenosis and other vascular abnormalities in a case of pheochromocytoma. A high index of suspicion is necessary to enable both entities to be diagnosed preoperatively and allow proper planning of surgical therapy. Incomplete diagnosis may lead to persistent hypertension postoperatively in a case of associated renal artery stenosis.

Quantum communication under channel uncertainty

Energy Technology Data Exchange (ETDEWEB)

Noetzel, Janis Christian Gregor

2012-09-06

This work contains results concerning transmission of entanglement and subspaces as well as generation of entanglement in the limit of arbitrary many uses of compound- and arbitrarily varying quantum channels (CQC, AVQC). In both cases, the channel is described by a set of memoryless channels. Only forward communication between one sender and one receiver is allowed. A code is said to be ''good'' only, if it is ''good'' for every channel out of the set. Both settings describe a scenario, in which sender and receiver have only limited channel knowledge. For different amounts of information about the channel available to sender or receiver, coding theorems are proven for the CQC. For the AVQC, both deterministic and randomised coding schemes are considered. Coding theorems are proven, as well as a quantum analogue of the Ahlswede-dichotomy. The connection to zero-error capacities of stationary memoryless quantum channels is investigated. The notion of symmetrisability is defined and used for both classes of channels.

Verapamil stereoisomers induce antiproliferative effects in vascular smooth muscle cells via autophagy

Energy Technology Data Exchange (ETDEWEB)

Salabei, Joshua K. [Diabetes and Obesity Center, University of Louisville, Louisville, KY 40202 (United States); Department of Biochemistry and Molecular Biology, University of Louisville, Louisville, KY 40202 (United States); Balakumaran, Arun [Department of Pathology, University of Texas Medical Branch, Galveston, TX 77555‐0438 (United States); Frey, Justin C. [Department of Biology, University of Wisconsin-Eau Claire, Eau Claire, WI 54702 (United States); Boor, Paul J. [Department of Pathology, University of Texas Medical Branch, Galveston, TX 77555‐0438 (United States); Treinen-Moslen, Mary [Department of Internal Medicine, University of Texas Medical Branch, Galveston, TX 77555‐0609 (United States); Department of Pathology, University of Texas Medical Branch, Galveston, TX 77555‐0438 (United States); Conklin, Daniel J., E-mail: dj.conklin@louisville.edu [Diabetes and Obesity Center, University of Louisville, Louisville, KY 40202 (United States); Division of Cardiovascular Medicine, University of Louisville, Louisville, KY 40202 (United States); Department of Biology, University of Wisconsin-Eau Claire, Eau Claire, WI 54702 (United States); Department of Pathology, University of Texas Medical Branch, Galveston, TX 77555‐0438 (United States)

2012-08-01

Calcium channel blockers (CCBs) are important in the management of hypertension and limit restenosis. Although CCB efficacy could derive from decreased blood pressure, other mechanisms independent of CCB activity also can contribute to antiproliferative action. To understand mechanisms of CCB-mediated antiproliferation, we studied two structurally dissimilar CCBs, diltiazem and verapamil, in cultured rat vascular smooth muscle cells (VSMC). To elucidate CCB-independent effects, pure stereoisomers of verapamil (R-verapamil, inactive VR; S-verapamil, active, VS) were used. The effects of CCB exposure on cell viability (MTT reduction), cell proliferation ({sup 3}H-thymidine incorporation), VSMC morphology by light and transmission electron microscopy (TEM) and autophagy (LC3I/II, ATG5) were measured. In general, verapamil, VR or VS treatment alone (80 μM) appreciably enhanced MTT absorbance although higher concentrations (VR or VS) slightly decreased MTT absorbance. Diltiazem (140 μM) markedly decreased MTT absorbance (40%) at 120 h. VR or VS treatment inhibited {sup 3}H-thymidine incorporation (24 h) and induced cytological alterations (i.e., karyokinesis, enhanced perinuclear MTT deposition, accumulated perinuclear “vacuoles”). TEM revealed perinuclear “vacuoles” to be aggregates of highly laminated and electron-dense vesicles resembling autophagosomes and lysosomes, respectively. Increased autophagosome activity was confirmed by a concentration-dependent increase in LC3-II formation by Western blotting and by increased perinuclear LC3-GFP{sup +} puncta in verapamil-treated VSMC. Verapamil stereoisomers appeared to decrease perinuclear mitochondrial density. These observations indicate that antiproliferative effects of verapamil stereoisomers are produced by enhanced mitochondrial damage and upregulated autophagy in VSMC. These effects are independent of CCB activity indicating a distinct mechanism of action that could be targeted for more efficacious anti

[Vascular access guidelines for hemodialysis].

Science.gov (United States)

Rodríguez Hernández, J A; González Parra, E; Julián Gutiérrez, J M; Segarra Medrano, A; Almirante, B; Martínez, M T; Arrieta, J; Fernández Rivera, C; Galera, A; Gallego Beuter, J; Górriz, J L; Herrero, J A; López Menchero, R; Ochando, A; Pérez Bañasco, V; Polo, J R; Pueyo, J; Ruiz, Camps I; Segura Iglesias, R

2005-01-01

Quality of vascular access (VA) has a remarkable influence in hemodialysis patients outcomes. Dysfunction of VA represents a capital cause of morbi-mortality of these patients as well an increase in economical. Spanish Society of Neprhology, aware of the problem, has decided to carry out a revision of the issue with the aim of providing help in comprehensión and treatment related with VA problems, and achieving an homogenization of practices in three mayor aspects: to increase arteriovenous fistula utilization as first vascular access, to increment vascular access monitoring practice and rationalise central catheters use. We present a consensus document elaborated by a multidisciplinar group composed by nephrologists, vascular surgeons, interventional radiologysts, infectious diseases specialists and nephrological nurses. Along six chapters that cover patient education, creation of VA, care, monitoring, complications and central catheters, we present the state of the art and propose guidelines for the best practice, according different evidence based degrees, with the intention to provide help at the professionals in order to make aproppiate decissions. Several quality standars are also included.

Pulmonary vascular complications in portal hypertension and liver disease: A concise review

Directory of Open Access Journals (Sweden)

M. Porres-Aguilar

2013-01-01

Full Text Available Chronic liver disease and/or portal hypertension may be associated with one of the two pulmonary vascular complications: portopulmonary hypertension and hepatopulmonary syndrome. These pulmonary vascular disorders are notoriously underdiagnosed; however, they have a substantial negative impact on survival and require special attention in order to understand their diagnostic approach and to select the best therapeutic options. Portopulmonary hypertension results from excessive vasoconstriction, vascular remodeling, and proliferative and thrombotic events within the pulmonary circulation that lead to progressive right ventricular failure and ultimately to death. On the other hand, abnormal intrapulmonary vascular dilations, profound hypoxemia, and a wide alveolar-arterial gradient are the hallmarks of the hepatopulmonary syndrome, resulting in difficult-to-treat hypoxemia. The aim of this review is to summarize the latest pathophysiologic concepts, diagnostic approach, therapy, and prognosis of portopulmonary hypertension and hepatopulmonary syndrome, as well as to discuss the role of liver transplantation as a definitive therapy in selected patients with these conditions.

Laser therapy and sclerotherapy in the treatment of oral and maxillofacial hemangioma and vascular malformations

Science.gov (United States)

Crişan, Bogdan; BǎciuÅ£, Mihaela; BǎciuÅ£, Grigore; Crişan, Liana; Bran, Simion; Rotar, Horatiu; Moldovan, Iuliu; Vǎcǎraş, Sergiu; Mitre, Ileana; Barbur, Ioan; Magdaş, Andreea; Dinu, Cristian

2016-03-01

Hemangioma and vascular malformations in the field of oral and maxillofacial surgery is a pathology more often found in recent years in patients. The aim of this study was to evaluate the efficacy of the laser photocoagulation performed with a diode laser (Ga-Al-As) 980 nm wavelength in the treatment of vascular lesions which are located on the oral and maxillofacial areas, using color Doppler ultrasonography for evaluation of the results. We also made a comparison between laser therapy and sclerotherapy in order to establish treatment protocols and recommendations associated with this pathology. We conducted a controlled study on a group of 92 patients (38 male and 54 female patients, with an average age of 36 years) having low flow hemangioma and vascular malformations. Patients in this trial received one of the methods of treatment for vascular lesions such as hemangioma and vascular malformations: laser therapy or sclerotherapy. After laser therapy we have achieved a reduction in size of hemangioma and vascular malformations treated with such a procedure, and the aesthetic results were favorable. No reperfusion or recanalization of laser treated vascular lesions was observed after an average follow-up of 6 to 12 months. In case of sclerotherapy a reduction in the size of vascular lesions was also obtained. The 980 nm diode laser has been proved to be an effective tool in the treatment of hemangioma and vascular malformations in oral and maxillofacial area. Laser therapy in the treatment of vascular lesions was more effective than the sclerotherapy procedure.

Effect of channel-protein interaction on translocation of a protein-like chain through a finite channel

International Nuclear Information System (INIS)

Sun Ting-Ting; Ma Hai-Zhu; Jiang Zhou-Ting

2012-01-01

We study the translocation of a protein-like chain through a finite cylindrical channel using the pruned-enriched Rosenbluth method (PERM) and the modified orientation-dependent monomer-monomer interaction (ODI) model. Attractive channels (in cp = −2.0, −1.0, −0.5), repulsive channels (in cp = 0.5, 1.0, 2.0), and a neutral channel (in cp = 0) are discussed. The results of the chain dimension and the energy show that Z 0 = 1.0 is an important case to distinguish the types of the channels. For the strong attractive channel, more contacts form during the process of translocation. It is also found that an external force is needed to drive the chain outside of the channel with the strong attraction. While for the neutral, the repulsive, and the weak attractive channels, the translocation is spontaneous. (interdisciplinary physics and related areas of science and technology)

Imaging after vascular gene therapy

International Nuclear Information System (INIS)

Manninen, Hannu I.; Yang, Xiaoming

2005-01-01

Targets for cardiovascular gene therapy currently include limiting restenosis after balloon angioplasty and stent placement, inhibiting vein bypass graft intimal hyperplasia/stenosis, therapeutic angiogenesis for cardiac and lower-limb ischemia, and prevention of thrombus formation. While catheter angiography is still standard method to follow-up vascular gene transfer, other modern imaging techniques, especially intravascular ultrasound (IVUS), magnetic resonance (MR), and positron emission tomography (PET) imaging provide complementary information about the therapeutic effect of vascular gene transfer in humans. Although molecular imaging of therapeutic gene expression in the vasculatures is still in its technical development phase, it has already offered basic medical science an extremely useful in vivo evaluation tool for non- or minimally invasive imaging of vascular gene therapy

Channel Simulation in Quantum Metrology