Search results for "oxygenation"
showing 10 items of 237 documents
Novel technologies to detect atelectotrauma in the injured lung
2010
ABSTRACTCyclical recruitment and derecruitment of lung parenchyma (R/D) remains a serious problem in ALI/ARDS patients, defined as atelectotrauma. Detection of cyclical R/D to titrate the optimal respiratory settings is of high clinical importance. Image-based technologies that are capable of detecting changes of lung ventilation within a respiratory cycle include dynamic computed tomography (dCT), synchrotron radiation computed tomography (SRCT), and electrical impedance tomography (EIT). Time-dependent intra-arterial oxygen tension monitoring represents an alternative approach to detect cyclical R/D, as cyclical R/D can result in oscillations of PaO2 within a respiratory cycle. Continuous…
Effect of Supplemental Oxygen versus Dobutamine Administration on Liver Oxygen Tension in dPP-Guided Normovolemic Pigs
2008
<i>Background:</i> Difference in pulse pressure (dPP) confirms adequate intravascular filling as a prerequisite for tissue perfusion. We hypothesized that both oxygen and dobutamine increase liver tissue oxygen tension (pt<i>O</i><sub>2</sub>). <i>Methods:</i> Eight anesthetized pigs received dPP-guided fluid management. Hepatic p<i>O</i><sub>2</sub> was measured with Clark-type electrodes placed subcapsularly, and on the liver surface. Pigs received: (1) supplemental oxygen (F<sub>i</sub><i>O</i><sub>2</sub> 1.0); (2) dobutamine 2.5 μg/kg/min, and (3) dobutamine 5 μg/kg/min. Data wer…
Systemic PaO2 oscillations cause mild brain injury in a pig model
2016
OBJECTIVE: Systemic PaO2 oscillations occur during cyclic recruitment and derecruitment of atelectasis in acute respiratory failure and might harm brain tissue integrity. DESIGN: Controlled animal study. SETTING: University research laboratory. SUBJECTS: Adult anesthetized pigs. INTERVENTIONS: Pigs were randomized to a control group (anesthesia and extracorporeal circulation for 20 hr with constant PaO2, n = 10) or an oscillation group (anesthesia and extracorporeal circulation for 20 hr with artificial PaO2 oscillations [3 cycles min⁻¹], n = 10). Five additional animals served as native group (n = 5). MEASUREMENTS AND MAIN RESULTS: Outcome following exposure to artificial PaO2 oscillations…
Correlation of skeletal muscle blood oxygenation level-dependent MRI and skin laser doppler flowmetry in patients with systemic sclerosis
2013
Purpose To investigate the origin of skeletal muscle BOLD MRI alterations in patients with systemic sclerosis (SSc) by correlating BOLD MRI T2* signal of calf muscles with microcirculatory blood flow of calf skin measured by laser Doppler flowmetry (LDF). Materials and Methods BOLD MRI (3T) and LDF measurements were performed in 12 consecutive SSc patients (6 women, 6 men; mean age 54.0 ± 10.0 years) and 12 healthy volunteers (4 men, 8 women; mean age 44.7 ± 13.1 years). For both modalities, the same cuff compression paradigm at mid-thigh level was used. LDF datasets were acquired using a PeriScan PIM II Imager (Perimed AB, Stockholm, Sweden) at the upper calf corresponding to the level of …
Near-Infrared Hemoencephalography for Monitoring Blood Oxygenation in Prefrontal Cortical Areas in Diagnosis and Therapy of Developmental Dyslexia
2013
The purpose of this study was to check empirically the relevance of the near-infrared hemoencephalography (NIR-HEG), which assesses local brain blood oxygenation, in facilitation of the diagnosis and behavioral therapy in dyslexics. The study was carried out in children and teenagers with physiologically recognized dyslexia, of three increasing age-groups: 6–7, 9–10, and 19–20 years old. Healthy age- and gender-matched subjects were used as controls. Left and right prefrontal cortical areas were targeted for the NIR-HEG measurements that were taken at baseline in both controls and dyslexics and then after a 10-day course of midriff breathing exercise combined with a standard vocal and writi…
Synthesis of Spirovetivane Sesquiterpenes from Santonin. Synthesis of (+)-Anhydro-?-rotunol and All Diastereomers of 6,11-Spirovetivadiene.
2005
The synthesis of the spirovetivane sesquiterpenes (+)-anhydro-beta-rotunol and all the diastereomers of 6,11-spirovetivadiene in enantiomerically pure form has been achieved starting from santonin. The key step is the silicon-guided acid-promoted rearrangement of a 1-trimethylsilyl-4,5-epoxyeudesmane prepared from santonin in several steps involving lactone reductive opening, conjugate addition of TMSLi-CuCN, deoxygenation of a carbonyl group, and epoxidation. Rearrangement of the epoxide gave a spiro[4,5]decanediol which was used as a synthetic intermediate. From this compound, (+)-anhydro-beta-rotunol was prepared after elimination of the primary hydroxyl group in the side chain, followed…
Quaternary relaxations in sol-gel encapsulated hemoglobin studied via NIR and UV spectroscopy.
2007
In this work, we study the kinetics of the R --T transition in hemoglobin using a combination of near-infrared and near-ultraviolet spectroscopy. We use a sol-gel encapsulation protocol to decelerate the conformational transitions and to avoid spectral perturbations arising from ligand migration and recombination. We monitor two spectroscopic markers: band III in the near-IR, which is a fine probe of the heme pocket conformation, and the tryptophan band in the near-UV, which probes the formation of the Trpbeta37-Aspalpha94 hydrogen bond, characteristic of the T structure, at the critical alpha1beta2 subunit interface. The time evolution of these two bands is monitored after deoxygenation of…
Multiple sulfur and carbon isotope composition of sediments from the Belingwe Greenstone Belt (Zimbabwe): A biogenic methane regulation on mass indep…
2013
Abstract To explore the linkage between mass-independent sulfur isotope fractionation (MIF-S) and δ13Corg excursions during the Neoarchean, as well as the contemporary redox state and biogeochemical cycling of carbon and sulfur, we report the results of a detailed carbon and multiple sulfur (δ34S, δ33S, δ36S) isotopic study of the ∼2.7 Ga Manjeri and ∼2.65 Ga Cheshire formations of the Ngezi Group (Belingwe Greenstone Belt, Zimbabwe). Multiple sulfur isotope data show non-zero Δ33S and Δ36S values for sediments older than 2.4 Ga (i.e. prior to the Great Oxidation Event, GOE), indicating MIF-S thought to be associated with low atmospheric oxygen concentration. However, in several 2.7–2.5 Ga …
Tumor hypoxia and therapeutic resistance
2008
For many years, the identification of tumor hypoxia, its systematic characterization and the assessment of its clinical relevance were not possible due to the lack of methods suitable for the routine measurement of intratumoral oxygen tensions in patients. In the late 1980s, a novel and clinically applicable standardized procedure was established enabling the determination of tumor oxygenation in accessible primary tumors, local recurrences, and metastatic lesions in patients using a computerized polarographic needle electrode system (Vaupel et al. 1991; Hockel et al. 1991). Within a relatively short period of time, the significance of tumor oxygenation for therapy outcome became evident in…
Consequences of neonatal resuscitation with supplemental oxygen.
2008
There has been considerable controversy surrounding the optimal inspired oxygen concentration for resuscitation of term and preterm infants. We have developed a rat pup model to quantify both physiologic and biochemical parameters associated with normoxic vs. hyperoxic resuscitation. We have confirmed existing human data that hyperoxic resuscitation of rat pups is associated with a significant delay in onset of spontaneous respiratory efforts. Both 40% and 100% inspired oxygen delayed onset of respiratory activity when compared to 21% oxygen. We have also documented, in the rat pup model, that hyperoxic resuscitation is associated with reduced levels of glutathione at 24 hours post resuscit…