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hydrostatic pressure in blood

Hongwei Yuan, Sven Poeggel, Thomas Newe, Elfed Lewis, Charusluk Viphavakit, Gabriel Leen
A comprehensive study of the effect of a wide range of controlled human subject motion on Photoplethysmographic signals is reported. The investigation includes testing of two separate groups of 5 and 18 subjects who were asked to undertake set exercises whilst simultaneously monitoring a wide range of physiological parameters including Breathing Rate, Heart Rate and Localised Blood Pressure using commercial clinical sensing systems. The unique finger mounted PPG probe equipped with miniature three axis accelerometers for undertaking this investigation was a purpose built in-house version which is designed to facilitate reproducible application to a wide range of human subjects and the study of motion...
March 10, 2017: Sensors
Utako Yokoyama, Yuta Tonooka, Ryoma Koretake, Taisuke Akimoto, Yuki Gonda, Junichi Saito, Masanari Umemura, Takayuki Fujita, Shinya Sakuma, Fumihito Arai, Makoto Kaneko, Yoshihiro Ishikawa
Shortage of autologous blood vessel sources and disadvantages of synthetic grafts have increased interest in the development of tissue-engineered vascular grafts. However, tunica media, which comprises layered elastic laminae, largely determines arterial elasticity, and is difficult to synthesize. Here, we describe a method for fabrication of arterial grafts with elastic layer structure from cultured human vascular SMCs by periodic exposure to extremely high hydrostatic pressure (HP) during repeated cell seeding...
December 2017: Scientific Reports
Emmanuel Cherin, Johan M Melis, Raymond W Bourdeau, Melissa Yin, Dennis M Kochmann, F Stuart Foster, Mikhail G Shapiro
Gas vesicles (GVs) are a new and unique class of biologically derived ultrasound contrast agents with sub-micron size whose acoustic properties have not been fully elucidated. In this study, we investigated the acoustic collapse pressure and behavior of Halobacterium salinarum gas vesicles at transmit center frequencies ranging from 12.5 to 27.5 MHz. The acoustic collapse pressure was found to be above 550 kPa at all frequencies, nine-fold higher than the critical pressure observed under hydrostatic conditions...
March 1, 2017: Ultrasound in Medicine & Biology
Zachary K Garrett, James Pearson, Andrew W Subudhi
Cerebral autoregulation (CA) is thought to maintain relatively constant cerebral blood flow (CBF) across normal blood pressures. To determine if postural changes alter CA, we measured cerebral blood flow velocity (CBFv) in the middle cerebral arteries, mean arterial blood pressure (MABP), cardiac output (Q), and end-tidal carbon dioxide (PETCO2) in 18 healthy individuals (11 female and seven male; 26 ± 9 years) during repeated periods of supine and seated rest. Multiple regression was used to evaluate the influence of PETCO2, MABP, Q, and hydrostatic pressure on CBFv...
February 2017: Physiological Reports
Magali Araujo, William J Welch, Xiaoyan Zhou, Kathleen Sullivan, Shawn Walsh, Alexander Pasternak, Christopher S Wilcox
The Na+/K+/2Cl- cotransporter (NKCC2) on the loop of Henle is the site of action of furosemide. Since outer medullary potassium channel (ROMK) inhibitors prevent reabsorption by NKCC2, we tested the hypothesis that ROMK inhibition with a novel, selective ROMK inhibitor (Compound C) blocks tubuloglomerular feedback (TGF) and reduces vascular resistance. Loop perfusion of either ROMK inhibitor or furosemide caused dose-dependent blunting of TGF, but the response to furosemide was 10-fold more sensitive (IC50= 10-6M for furosemide and IC50=10-5M for Compound C)...
February 22, 2017: American Journal of Physiology. Renal Physiology
Manuel Gehlen, Vartan Kurtcuoglu, Marianne Schmid Daners
BACKGROUND: Postural changes are related to changes in cerebrospinal fluid (CSF) dynamics. While sitting up leads to a decrease in cranial CSF pressure, it also causes shifts in the craniospinal CSF volume and compliance distribution. We hypothesized that jugular vein collapse in upright posture is a major contributor to these shifts in CSF volume and compliance. METHODS: To test this hypothesis, we implemented a mathematical lumped-parameter model of the CSF system and the relevant parts of the cardiovascular system...
February 16, 2017: Fluids and Barriers of the CNS
José Cunha-Vaz
Retinal diseases are the main causes of blindness in the Western world. Diabetic retinopathy and age-related macular degeneration continue to increase in prevalence and as main causes of vision loss. Intravitreal anti-VEGF and steroid injections have raised new expectations for their successful treatment. These agents act by stabilizing the blood-retinal barrier (BRB). Our group defined the BRB by identifying for the first time the tight junctions that unite retinal endothelial cells and are the basis for the inner BRB, an observation later confirmed in retinal pigment epithelial cells and in brain vessels...
2017: Ophthalmologica. Journal International D'ophtalmologie
Jun Negishi, Yoshihide Hashimoto, Akitatsu Yamashita, Yongwei Zhang, Tsuyoshi Kimura, Akio Kishida, Seiichi Funamoto
Following small-diameter vascular grafting, blood vessels fail to retain excellent antithrombotic function and therefore require application of antithrombogenic drugs. We have previously reported early attachment of endothelial cells to the luminal surface of high hydrostatic pressure (HHP)-decellularized arteries after transplantation. In addition, the graft retained antithrombotic function by endothelialization and remained open for several weeks. To fabricate tube grafts of optimal size and shape for small-diameter vascular grafting, we evaluated decellularized porcine aorta sheets as a suitable antithrombogenic material...
January 28, 2017: Journal of Biomedical Materials Research. Part A
Hideki Moriyama
Joints are composed of several different tissues(cartilage, capsule, meniscus, and ligament), and articular cartilage plays an important role in maintaining mechanical competence during exercise. Weight-bearing exercise has several benefit, including improved blood and synovial fluid circulation in a given joint. Consistent moderate activities facilitate cycles of anabolism and catabolism. Mechanical stresses are crucial for the maintenance of the morphologic and functional integrity of articular cartilage...
2017: Clinical Calcium
Kanchana Kengkoom, Sumate Ampawong
Phikud Navakot (PN), Thai herbal remedy in National List of Essential Medicines, has been claimed to reduce many cardiovascular symptoms especially dizziness and fainting. Apart from blood supply, erythrocyte morphology, in both shape and size, is one of the main consideration factors in cardiovascular diseases and may be affected by vascular oxidative stress. However, little is known about antioxidative property of PN on erythrocyte to preserve red blood cell integrity. In this study, 1,000 μM hydrogen peroxide-induced oxidative stress was conducted on sheep erythrocyte...
2016: Evidence-based Complementary and Alternative Medicine: ECAM
Stephen B Hladky, Margery A Barrand
The two major interfaces separating brain and blood have different primary roles. The choroid plexuses secrete cerebrospinal fluid into the ventricles, accounting for most net fluid entry to the brain. Aquaporin, AQP1, allows water transfer across the apical surface of the choroid epithelium; another protein, perhaps GLUT1, is important on the basolateral surface. Fluid secretion is driven by apical Na(+)-pumps. K(+) secretion occurs via net paracellular influx through relatively leaky tight junctions partially offset by transcellular efflux...
October 31, 2016: Fluids and Barriers of the CNS
Petter Bjornstad, Marko Škrtić, Yuliya Lytvyn, David M Maahs, Richard J Johnson, David Z I Cherney
Diabetic kidney disease (DKD) remains the leading cause of end-stage renal disease. A major challenge in preventing DKD is the difficulty in identifying high-risk patients at an early, pre-clinical stage. Albuminuria and eGFR as measures of renal function in DKD research and clinical practice are limited by regression of one-third of patients with microalbuminuria to normoalbuminuria and eGFR is biased and imprecise in the normal-elevated range. Moreover, existing methods that are used to assess renal function do not give detailed insight into the location of the renal hemodynamic effects of pharmacological agents at the segmental level...
September 7, 2016: American Journal of Physiology. Renal Physiology
E Scott Helton, Steven Palladino, Eroboghene E Ubogu
Microvascular barrier permeability to water is an essential biophysical property required for the homeostatic maintenance of unique tissue microenvironments. This is of particular importance in peripheral nerves where strict control of ionic concentrations is needed for axonal signal transduction. Previous studies have associated inflammation, trauma, toxin exposure and metabolic disease with increases in water influx and hydrostatic pressure in peripheral nerves with resultant endoneurial edema that may impair axonal function...
January 2017: Microvascular Research
Yoshio Takei, Ippei Suzuki, Marty Kwok-Shing Wong, Ryan Milne, Simon Moss, Katsufumi Sato, Ailsa Hall
An animal-borne blood sampler with data logging functions was developed for phocid seals which collected two blood samples for the comparison of endocrinological/biochemical parameters under two different conditions. The sampler can be triggered by preset hydrostatic pressure, acceleration (descending or ascending), temperature and time, and also manually by light. The sampling was reliable with >78% successful attempts to collect blood samples. Contamination of fluids in the tubing to the next blood sample was <1%, following the prior clearance of the tubing to a waste syringe...
August 31, 2016: American Journal of Physiology. Regulatory, Integrative and Comparative Physiology
I Tan, B Spronck, T Delhaas, K Reesink, H Kiat, E Barin, M Butlin, A Avolio
OBJECTIVE: Aortic stiffness, as measured by carotid-femoral pulse wave velocity (cfPWV), is an independent marker for cardiovascular morbidity and mortality, but is dependent on blood pressure (BP) and possibly heart rate (HR). Acute HR changes are often accompanied by increased BP. This presents the need to quantify the BP-independent effect of HR on cfPWV. DESIGN AND METHOD: Individuals (n = 52, age 40-93 years, 11 female) with in situ cardiac pacemakers were paced at 60, 70, 80, 90 and 100 bpm with BP and cfPWV measured at each pacing step...
September 2016: Journal of Hypertension
K Anttila, T Streng, J Pispa, M Vainio, M Nikinmaa
AIM: We studied if available oxygen without induced mechanical stretch regulates the release of the biologically active B-type natriuretic peptide (BNP) from Langendorff heart. METHODS: Rat hearts were isolated and perfused with a physiological Krebs-Henseleit solution at a constant hydrostatic pressure in Langendorff setup. The basal O2 level of perfusate (24.4±0.04 mg L(-1) ) was gradually lowered to 3.0±0.01 mg L(-1) over 20 minutes using N2 gas (n=7). BNP and O2 level were measured from coronary flow...
August 6, 2016: Acta Physiologica
Arshan Nazempour, Chrystal R Quisenberry, Bernard J Van Wie, Nehal I Abu-Lail
Articular cartilage (AC), tissue with the lowest volumetric cellular density, is not supplied with blood and nerve tissue resulting in limited ability for self-repair upon injury. Because there is no treatment capable of fully restoring damaged AC, tissue engineering is being investigated. The emphasis of this field is to engineer functional tissues in vitro in bioreactors capable of mimicking in vivo envi- ronments required for appropriate cellular growth and differentiation. In a step towards engineering AC, human adipose-derived stem cells were differentiated in a unique centrifugal bioreactor under oscillating hydrostatic pressure (OHP) and supply of transforming growth factor beta 3 (TGF-β3) that mimic in vivo environments...
March 2016: Journal of Nanoscience and Nanotechnology
Tatsuya J Arai, Rebecca J Theilmann, Rui Carlos Sá, Michael T Villongco, Susan R Hopkins
KEY POINTS: Pulmonary perfusion measurement using magnetic resonance imaging combined with deformable image registration enabled us to quantify the change in the spatial distribution of pulmonary perfusion at different lung volumes. The current study elucidated the effects of tidal volume lung inflation [functional residual capacity (FRC) + 500 ml and FRC + 1 litre] on the change in pulmonary perfusion distribution. Changes in hydrostatic pressure distribution as well as transmural pressure distribution due to the change in lung height with tidal volume inflation are probably bigger contributors to the redistribution of pulmonary perfusion than the changes in pulmonary vasculature resistance caused by lung tissue stretch...
November 1, 2016: Journal of Physiology
David J Kinahan, Sinéad M Kearney, Niamh A Kilcawley, Philip L Early, Macdara T Glynn, Jens Ducrée
Here we present retrieval of Peripheral Blood Mononuclear Cells by density-gradient medium based centrifugation for subsequent analysis of the leukocytes on an integrated microfluidic "Lab-on-a-Disc" cartridge. Isolation of white blood cells constitutes a critical sample preparation step for many bioassays. Centrifugo-pneumatic siphon valves are particularly suited for blood processing as they function without need of surface treatment and are 'low-pass', i.e., holding at high centrifugation speeds and opening upon reduction of the spin rate...
2016: PloS One
James Noraky, George C Verghese, David E Searls, Vasileios A Lioutas, Shruti Sonni, Ajith Thomas, Thomas Heldt
Intracranial pressure (ICP) should ideally be measured in many conditions affecting the brain. The invasiveness and associated risks of the measurement modalities in current clinical practice restrict ICP monitoring to a small subset of patients whose diagnosis and treatment could benefit from ICP measurement. To expand validation of a previously proposed model-based approach to continuous, noninvasive, calibration-free, and patient-specific estimation of ICP to patients with subarachnoid hemorrhage (SAH), we made waveform recordings of cerebral blood flow velocity in several major cerebral arteries during routine, clinically indicated transcranial Doppler examinations for vasospasm, along with time-locked waveform recordings of radial artery blood pressure (APB), and ICP was measured via an intraventricular drain catheter...
2016: Acta Neurochirurgica. Supplement
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