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"Oxygen kinetics"

Fangyao Hu, Karthik Vishwanath, Joseph K Salama, Alaattin Erkanli, Bercedis Peterson, James R Oleson, Walter T Lee, David M Brizel, Nimmi Ramanujam, Mark W Dewhirst
PURPOSE: To test whether oxygenation kinetics correlate with the likelihood for local tumor control after fractionated radiation therapy. METHODS AND MATERIALS: We used diffuse reflectance spectroscopy to noninvasively measure tumor vascular oxygenation and total hemoglobin concentration associated with radiation therapy of 5 daily fractions (7.5, 9, or 13.5 Gy/d) in FaDu xenografts. Spectroscopy measurements were obtained immediately before each daily radiation fraction and during the week after radiation therapy...
October 1, 2016: International Journal of Radiation Oncology, Biology, Physics
Scott L Hummel, John Herald, Craig Alpert, Kimberlee A Gretebeck, Wendy S Champoux, Donald R Dengel, Peter V Vaitkevicius, Neil B Alexander
BACKGROUND: Submaximal oxygen uptake measures are more feasible and may better predict clinical cardiac outcomes than maximal tests in older adults with heart failure (HF). We examined relationships between maximal oxygen uptake, submaximal oxygen kinetics, functional mobility, and physical activity in older adults with HF and reduced ejection fraction. METHODS: Older adults with HF and reduced ejection fraction (n = 25, age 75 ± 7 years) were compared to 25 healthy age- and gender-matched controls...
July 2016: Journal of Geriatric Cardiology: JGC
K Dipla, E Kintiraki, I Grigoriadou, G Triantafyllou, A Triantafyllou, I Zografou, I S Vrabas, A Zafeiridis, D G Goulis, S Douma
OBJECTIVE: Patients with Gestational diabetes mellitus (GDM) are at increased risk for gestational hypertension. Although GDM is considered a mild metabolic dysfunction, some studies have associated GDM with alterations of endothelial responsiveness, whereas, other studies suggested that the time of exposure to hyperglycemia might be insufficient to induce micro- and macrovascular dysfunction. Near-infrared spectroscopy (NIRS) allows a non-invasive monitoring of functional changes in oxygenated hemoglobin (O2Hb) and oxygen tissue saturation (TSI) and the assessment of microvascular function within the skeletal muscle...
September 2016: Journal of Hypertension
Alexandre Super, Nicolas Jaccard, Marco Paulo Cardoso Marques, Rhys Jarred Macown, Lewis Donald Griffin, Farlan Singh Veraitch, Nicolas Szita
Oxygen plays a key role in stem cell biology as a signaling molecule and as an indicator of cell energy metabolism. Quantification of cellular oxygen kinetics, i.e. the determination of specific oxygen uptake rates (sOURs), is routinely used to understand metabolic shifts. However current methods to determine sOUR in adherent cell cultures rely on cell sampling, which impacts on cellular phenotype. We present real-time monitoring of cell growth from phase contrast microscopy images, and of respiration using optical sensors for dissolved oxygen...
September 2016: Biotechnology Journal
David A Giles, Vanesa España-Romero, Inmaculada Garrido, Alex de la O Puerta, Keeron Stone, Simon Fryer
PURPOSE: This study examined differences in oxygenation kinetics in the non-dominant and dominant flexor digitorum profundus (FDP) of rock climbers. METHODS: Participants consisted of 28 sport climbers with a range of on-sight abilities (6a+ to 8a French Sport). Using near infrared spectroscopy, oxygenation kinetics of the FDP was assessed by calculating the time to half recovery (t½ recovery) of the tissue saturation index (TSI) following 3-5 min of ischemia. RESULTS: A 2-way mixed model ANOVA found a non-significant interaction (p =0...
May 3, 2016: International Journal of Sports Physiology and Performance
Tobias Bornhütter, Judith Pohl, Christian Fischer, Irena Saltsman, Atif Mahammed, Zeev Gross, Beate Röder
Recent studies show the feasibility of photodynamic inactivation of green algae as a vital step towards an effective photodynamic suppression of biofilms by using functionalized surfaces. The investigation of the intrinsic mechanisms of photodynamic inactivation in green algae represents the next step in order to determine optimization parameters. The observation of singlet oxygen luminescence kinetics proved to be a very effective approach towards understanding mechanisms on a cellular level. In this study, the first two-dimensional measurement of singlet oxygen kinetics in phototrophic microorganisms on surfaces during photodynamic inactivation is presented...
2016: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
Michael Pfitzner, Jan C Schlothauer, Estelle Bastien, Steffen Hackbarth, Lina Bezdetnaya, Henri-Pierre Lassalle, Beate Röder
BACKGROUND: Singlet oxygen observation is considered a valuable tool to assess and optimize PDT treatment. In complex systems, such as tumors in vivo, only the direct, time-resolved singlet oxygen luminescence detection can give reliable information about generation and interaction of singlet oxygen. Up to now, evaluation of kinetics was not possible due to insufficient signal-to-noise ratio. Here we present high signal-to-noise ratio singlet oxygen luminescence kinetics obtained in mouse tumor model under PDT relevant conditions...
June 2016: Photodiagnosis and Photodynamic Therapy
Martin Matejovic, Can Ince, Lakhmir S Chawla, Roland Blantz, Bruce A Molitoris, Mitchell H Rosner, Mark D Okusa, John A Kellum, Claudio Ronco
Novel therapeutic interventions are required to prevent or treat AKI. To expedite progress in this regard, a consensus conference held by the Acute Dialysis Quality Initiative was convened in April of 2014 to develop recommendations for research priorities and future directions. Here, we highlight the concepts related to renal hemodynamics in AKI that are likely to reveal new treatment targets on investigation. Overall, we must better understand the interactions between systemic, total renal, and glomerular hemodynamics, including the role of tubuloglomerular feedback...
January 2016: Journal of the American Society of Nephrology: JASN
Ryan A Boyd, Anthony Gandin, Asaph B Cousins
The photosynthetic assimilation of CO2 in C4 plants is potentially limited by the enzymatic rates of Rubisco, phosphoenolpyruvate carboxylase (PEPc), and carbonic anhydrase (CA). Therefore, the activity and kinetic properties of these enzymes are needed to accurately parameterize C4 biochemical models of leaf CO2 exchange in response to changes in CO2 availability and temperature. There are currently no published temperature responses of both Rubisco carboxylation and oxygenation kinetics from a C4 plant, nor are there known measurements of the temperature dependency of the PEPc Michaelis-Menten constant for its substrate HCO3 (-), and there is little information on the temperature response of plant CA activity...
November 2015: Plant Physiology
Anthony J Barron, Niti M Dhutia, Sven Gläser, Beate Koch, Ralf Ewert, Anne Obst, Marcus Dörr, Henry Völzke, Darrel P Francis, Roland Wensel
BACKGROUND: Cardiopulmonary exercise testing allows for assessment of cardiac and respiratory limitation, but is often affected by patient effort. Indices of oxygen kinetics, including the oxygen uptake efficiency slope (OUES), oxygen uptake-work-rate slope (VO2-WR slope) and the heart rate-oxygen uptake slope (HR-VO2 slope) are relatively effort independent but may be affected by patient characteristics. The objective of this study is to identify the impact of factors, such as age, gender, body size, respiratory function, smoking and beta-blockade on these parameters, as well as generate predictive equations...
June 2015: IJC Metabolic & Endocrine
Marc Fortin, Pierre-Yves Turgeon, Éric Nadreau, Pierre Grégoire, Louis-Gabriel Maltais, Mario Sénéchal, Steeve Provencher, François Maltais
BACKGROUND: Peak oxygen uptake (V˙O2peak) is a well-established prognostic marker in chronic heart failure (CHF). Cardiopulmonary exercise testing (CPET) provides physiological parameters other than V˙O2peak that might have prognostic value. We aimed at determining whether exercise recovery data kinetics have prognostic implications over V˙O2peak and Heart Failure Survival Score. METHODS: Exercise data from 200 consecutive CHF patients evaluated for possible heart transplantation and received CPET at our institution between 2004 and 2011 were analyzed...
October 2015: Canadian Journal of Cardiology
Satyam Sarma, Benjamin D Levine
Patients with heart failure with preserved ejection fraction (HFpEF) have similar degrees of exercise intolerance and dyspnea as patients with heart failure with reduced EF (HFrEF). The underlying pathophysiology leading to impaired exertional ability in the HFpEF syndrome is not completely understood, and a growing body of evidence suggests "peripheral," i.e., noncardiac, factors may play an important role. Changes in skeletal muscle function (decreased muscle mass, capillary density, mitochondrial volume, and phosphorylative capacity) are common findings in HFrEF...
September 15, 2015: Journal of Applied Physiology
Michael J Stark, Nicolette A Hodyl, Chad C Andersen
BACKGROUND: The underlying neuro-protective mechanisms of antenatal magnesium sulfate (MgSO(4)) in infants born preterm remain poorly understood. Early neonatal brain injury may be preceded by low cerebral blood flow (CBF) and elevated cerebral fractional tissue oxygen extraction (cFTOE). This study investigated the effect of antenatal MgSO(4) on cerebral oxygen delivery, consumption, and cFTOE in preterm infants. METHODS: CBF and tissue oxygenation index were measured, and oxygen delivery, consumption, and cFTOE calculated within 24 h of birth and at 48 and 72 h of life in 36 infants ≤ 30 wk gestation exposed to MgSO(4) and 29 unexposed infants...
September 2015: Pediatric Research
Ismail Ersan, Sedat Arikan, Huseyin Toman, Selcuk Kara, Baran Gencer, Mesut Erbas, Hasan Ali Tufan, Metehan Uzun
PURPOSE: To measure the partial pressure of oxygen (PO2) and carbon dioxide (PCO2) and the pH of aqueous humor (AH) and arterial blood samples from rabbits using a blood gas analyzer. METHODS: Twenty New Zealand rabbits were anesthetized intramuscularly with ketamine and xylazine and were then allowed to breathe room air. Using a gas blood analyzer, arterial blood and AH samples were analyzed for PO2, PCO2, and pH. RESULTS: The mean arterial blood pressure was 87...
March 2015: Arquivos Brasileiros de Oftalmologia
Eric M Shepard, David M Dooley
Copper-containing amine oxidases (CuAOs) use both copper and 2,4,5-trihydroxyphenylalanine quinone (TPQ) to catalyze the oxidative deamination of primary amines. The CuAO active site is highly conserved and comprised of TPQ and a mononuclear type II copper center that exhibits five-coordinate, distorted square pyramidal coordination geometry with histidine ligands and equatorially and axially bound water in the oxidized, resting state. The active site is buried within the protein, and CuAOs from various sources display remarkable diversity with respect to the composition of the active site channel and cofactor accessibility...
May 19, 2015: Accounts of Chemical Research
C C Andersen, S M Karayil, N A Hodyl, M J Stark
BACKGROUND: Elevated cerebral fractional tissue oxygen extraction (cFTOE; ≥0.4) predicts early brain injury in very preterm infants. While blood transfusion increases oxygen-carrying capacity, its ability to improve cerebral oxygen kinetics in the immediate newborn period remains unknown. OBJECTIVE: To investigate the effect of red blood cell (RBC) transfusion in the first 24 h of life on cFTOE in infants ≤29 weeks gestation. METHODS: cFTOE was calculated from cerebral tissue oxygenation index (TOI) and cutaneous oximetry measured over a 30 min epoch before and after transfusion...
September 2015: Archives of Disease in Childhood. Fetal and Neonatal Edition
Dengjie Chen, Chi Chen, Zhenbao Zhang, Zarah Medina Baiyee, Francesco Ciucci, Zongping Shao
Mixed conducting perovskite oxides are promising catalysts for high-temperature oxygen reduction reaction. Pristine SrCoO(3-δ) is a widely used parent oxide for the development of highly active mixed conductors. Doping a small amount of redox-inactive cation into the B site (Co site) of SrCoO(3-δ) has been applied as an effective way to improve physicochemical properties and electrochemical performance. Most findings however are obtained only from experimental observations, and no universal guidelines have been proposed...
April 29, 2015: ACS Applied Materials & Interfaces
Russell S Richardson, Claire Wary, D Walter Wray, Jan Hoff, Harry B Rossiter, Gwenael Layec, Pierre G Carlier
PURPOSE: At exercise onset, intramuscular oxidative energy production responds relatively slowly in comparison with the change in adenosine triphosphate demand. To determine whether the slow kinetics of oxidative adenosine triphosphate production is due to inadequate O2 supply or metabolic inertia, we studied the kinetics of intramyocellular deoxygenation (deoxy-myoglobin (Mb)) and metabolism (phosphocreatine (PCr)) using proton (1H) and phosphorus (31P) magnetic resonance spectroscopy in six healthy subjects (33 ± 5 yr)...
November 2015: Medicine and Science in Sports and Exercise
Ben Jones, David K Hamilton, Chris E Cooper
This study examined the effects of Sprint Interval Cycling (SIT) on muscle oxygenation kinetics and performance during the 30-15 intermittent fitness test (IFT). Twenty-five women hockey players of Olympic standard were randomly selected into an experimental group (EXP) and a control group (CON). The EXP group performed six additional SIT sessions over six weeks in addition to their normal training program. To explore the potential training-induced change, EXP subjects additionally completed 5 x 30s maximal intensity cycle testing before and after training...
2015: PloS One
Eleni Armeniakou, Georgia Perpati, Stavros Dimopoulos, Petros Roditis, Maria Avdikou, Nikolaos Barouchos, Vasiliki Dionisopoulou, Serafim Nanas
BACKGROUND: The goal of this study was to explore the relation between oxygen kinetics during constant work load submaximal cardiopulmonary exercise test (CPET) and disease severity in adult subjects with cystic fibrosis. METHODS: Fourteen adult subjects with cystic fibrosis (CF; 8 males, 22 ± 4 y old) and a mean Schwachman score of 73 ± 11 and 10 healthy individuals (5 males, 29 ± 4 y old) underwent pulmonary function tests at rest, maximal and constant work load submaximal CPET on a cycloergometer...
August 2015: Respiratory Care
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