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hydrostatic pressure in blood

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...
August 31, 2016: 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
Tidal volume lung inflation results in structural changes in the pulmonary circulation, potentially affecting pulmonary perfusion. We hypothesized that perfusion is recruited to regions receiving the greatest deformation from a tidal breath, thus ensuring ventilation-perfusion matching. Density normalized perfusion (DNP) MRI data were obtained in healthy subjects (n = 7) in the right lung at functional residual capacity (FRC), FRC+0.5 L, and FRC+1.0 L. Using deformable image registration, the displacement of a sagittal lung slice acquired at FRC to the larger volumes was calculated...
June 8, 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
Naoki Morimoto, Atsushi Mahara, Chizuru Jinno, Mami Ogawa, Natsuko Kakudo, Shigehiko Suzuki, Kenji Kusumoto, Toshia Fujisato, Tetsuji Yamaoka
We previously reported that exposure to a high hydrostatic pressure (HHP) of 200 MPa could completely inactivate porcine skin without damaging the extracellular matrix. In this study, we used an autologous porcine skin graft model and explored whether the skin inactivated by HHP could be engrafted without inflammation to the residual cellular components. Twenty-one full-thickness skin grafts of 1.5 × 1.5 cm in size were prepared from a minipig (n = 2). Grafts were either nonpressurized or pressurized to 100, 150, 200, 300, 500, or 1000 MPa (n = 3) and randomly implanted on the fascia and removed at 1 and 4 weeks after grafting...
March 21, 2016: Journal of Biomedical Materials Research. Part B, Applied Biomaterials
Joanna Stachowska-Pietka, Jacek Waniewski, Michael F Flessner, Bengt Lindholm
Clinical and animal studies suggest that peritoneal absorption of fluid and protein from dialysate to peritoneal tissue, and to blood and lymph circulation, occurs concomitantly with opposite flows of fluid and protein, i.e., from blood to dialysate. However, until now a theoretical explanation of this phenomenon has been lacking. A two-phase distributed model is proposed to explain the bidirectional, concomitant transport of fluid, albumin and glucose through the peritoneal transport system (PTS) during peritoneal dialysis...
June 1, 2016: American Journal of Physiology. Heart and Circulatory Physiology
Zhipeng Liao, Junning Chen, Wei Li, M Ali Darendeliler, Michael Swain, Qing Li
OBJECTIVES: This paper aimed to precisely locate centres of resistance (CRe) of maxillary teeth and investigate optimal orthodontic force by identifying the effective zones of orthodontic tooth movement (OTM) from hydrostatic stress thresholds in the periodontal ligament (PDL). METHODS: We applied distally-directed tipping and bodily forces ranging from 0.075 N to 3 N (7.5 g to 300 g) onto human maxillary teeth. The hydrostatic stress was quantified from nonlinear finite element analysis (FEA) and compared with normal capillary and systolic blood pressure for driving the tissue remodelling...
June 2016: Archives of Oral Biology
Richard L Hughson, Andrew D Robertson, Philippe Arbeille, J Kevin Shoemaker, James W E Rush, Katelyn S Fraser, Danielle K Greaves
Removal of the normal head-to-foot gravity vector and chronic weightlessness during spaceflight might induce cardiovascular and metabolic adaptations related to changes in arterial pressure and reduction in physical activity. We tested hypotheses that stiffness of arteries located above the heart would be increased postflight, and that blood biomarkers inflight would be consistent with changes in vascular function. Possible sex differences in responses were explored in four male and four female astronauts who lived on the International Space Station for 6 mo...
March 1, 2016: American Journal of Physiology. Heart and Circulatory Physiology
M V Baranov, V P Katuntsev, A V Shpakov, V M Baranov
A novel method of ground simulation in humans of physiological effects induced by the stay on the surface of celestial bodies with hypogravity was developed and successfully tested. This method is based on the change of gravity force angle, which decreases the gravitational component of the blood hydrostatic pressure characteristic of human vertical posture on the Earth and the load-weight onto the locomotor apparatus to the lower values expected at celestial bodies with hypogravity. The methodological requirements for ground simulation of the physiological effects of lunar gravity on human body are specified and substantiated by theoretical calculations...
January 2016: Bulletin of Experimental Biology and Medicine
Mark Butlin, Peta J Hathway, Zahra Kouchaki, Karen Peebles, Alberto P Avolio
Devices that estimate blood pressure from arterial pulse wave velocity (PWV) potentially provide continuous, ambulatory blood pressure monitoring. Accurate blood pressure estimation requires reliable quantification of the relationship between blood pressure and PWV. Regression to population normal values or, when using limb artery PWV, changing hydrostatic blood pressure within the limb provides a calibration index. Population lookup tables require accurate anthropometric correlates, assuming no individual variation...
August 2015: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
Shinsaku Tokuda, Young Hak Kim, Hisako Matsumoto, Shigeo Muro, Toyohiro Hirai, Michiaki Mishima, Mikio Furuse
The relationship between chronic inflammation and cancer is well known. The inflammation increases the permeability of blood vessels and consequently elevates pressure in the interstitial tissues. However, there have been only a few reports on the effects of hydrostatic pressure on cultured cells, and the relationship between elevated hydrostatic pressure and cell properties related to malignant tumors is less well understood. Therefore, we investigated the effects of hydrostatic pressure on the cultured epithelial cells seeded on permeable filters...
2015: PloS One
Mitchell P Wilson, Edward S Johnson, Cynthia Hawkins, Kerry Atkins, Wael Alshaya, Jeffrey A Pugh
Acute hemorrhagic presentation in pilocytic astrocytomas (PAs) has become increasingly recognized. This type of presentation poses a clinically emergent situation in those hemorrhages arising in PAs of the cerebellum, the most frequent site, because of the limited capacity of the posterior fossa to compensate for mass effect, predisposing to rapid neurological deterioration. As examples, we describe two cases of fatal hemorrhagic cerebellar PAs: one of a child with a slowly growing stereotypical WHO Grade I PA with a 1-year period of symptomatology that preceded a rapid clinical deterioration, and another of an asymptomatic child having a PA variant, presenting with progressive obtundation following a presumed Valsalva event...
April 2016: Journal of Neurosurgery. Pediatrics
Dongqing Guo, Shenghui Liang, Su Wang, Chengchun Tang, Bin Yao, Wenhui Wan, Hailing Zhang, Hui Jiang, Asif Ahmed, Zhiren Zhang, Yuchun Gu
An increasing number of mechano-sensitive ion channels in endothelial cells have been identified in response to blood flow and hydrostatic pressure. However, how these channels respond to flow under different physiological and pathological conditions remains unknown. Our results show that epithelial Na(+) channels (ENaCs) colocalize with hemeoxygenase-1 (HO-1) and hemeoxygenase-2 (HO-2) within the caveolae on the apical membrane of endothelial cells and are sensitive to stretch pressure and shear stress. ENaCs exhibited low levels of activity until their physiological environment was changed; in this case, the upregulation of HO-1, which in turn facilitated heme degradation and hence increased the carbon monoxide (CO) generation...
January 15, 2016: Journal of Cell Science
Mårten Jungner, Roger Siemund, Daniele Venturoli, Peter Reinstrup, Wilhelm SCHALéN, Peter Bentzer
BACKGROUND: Brain edema and intracranial hypertension is deleterious after traumatic brain injury (TBI), but the underlying pathophysiology is complex and poorly understood. One major subject of controversy is the time course and extent of blood-brain barrier (BBB) dysfunction following trauma, and previous studies in humans have only provided semi-quantitative data. The objective of the present study was therefore to quantify changes in BBB-permeability in the early course of TBI, when brain edema is still evolving...
May 2016: Minerva Anestesiologica
David R Pendergast, Richard E Moon, John J Krasney, Heather E Held, Paola Zamparo
Water covers over 70% of the earth, has varying depths and temperatures and contains much of the earth's resources. Head-out water immersion (HOWI) or submersion at various depths (diving) in water of thermoneutral (TN) temperature elicits profound cardiorespiratory, endocrine, and renal responses. The translocation of blood into the thorax and elevation of plasma volume by autotransfusion of fluid from cells to the vascular compartment lead to increased cardiac stroke volume and output and there is a hyperperfusion of some tissues...
October 2015: Comprehensive Physiology
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