Search results for "Centration"

Quantification of Regional Intrapulmonary Oxygen Partial Pressure Evolution during Apnea by 3He MRI

1999

We present a new method to determine in vivo the temporal evolution of intrapulmonary oxygen concentrations by functional lung imaging with hyperpolarized (3)Helium ((3)He-->). Single-breath, single-bolus visualization of (3)He--> administered to the airspaces is used to analyze nuclear spin relaxation caused by the local oxygen partial pressure p(O(2))(t). We model the dynamics of hyperpolarization in the lung by rate equations. Based hereupon, a double acquisition technique is presented to separate depolarization by RF pulses and oxygen induced relaxation. It permits the determination of p(O(2)) with a high accuracy of up to 3% with simultaneous flip angle calibration using no additional …

Comparison of the 45-Second/15-Second Intermittent Running Field Test and the Continuous Treadmill Test

2012

Purposes:To compare the physiological responses and maximal aerobic running velocity (MAV) during an incremental intermittent (45-s run/15-s rest) field test (45-15FIT) vs an incremental continuous treadmill test (TR) and to demonstrate that the MAV obtained during 45-15FIT (MAV45-15) was relevant to elicit a high percentage of maximal oxygen uptake (VO2max) during a 30-s/30-s intermittent training session.Methods:Oxygen uptake (VO2), heart rate (HR), and lactate concentration ([La]) were measured in 20 subjects during 2 maximal incremental tests and four 15-min intermittent tests. The time spent above 90% and 95% VO2max (t90% and t95% VO2max, respectively) was determined.Results:Maximal ph…

Lorcainide; II. Plasma concentration-effect relationship

1979

Spontaneous gastroesophageal reflux and airway patency during the night in adult asthmatics

2000

Controversies still exist on the role of nighttime gastroesophageal reflux (GER) in precipitating nocturnal asthma. We tested the relationship between GER and nocturnal bronchoconstriction by continuously and simultaneously monitoring both respiratory resistances and esophageal pH in seven asthmatics with moderate to severe GER disease. Twenty-nine GER episodes were found during the study night lasting more than 5 min (LGER) and 72 not longer than 5 min (SGER). Both long (LGER) and short (SGER) gastroesophageal refluxes were able to maintain significantly higher lower respiratory resistances (RLR) at the resolution of each GER episode (RLR(e)) with respect to baseline values. RLR, expressed…

Differences in sensitivity, maximal response and position of the concentration-response curve to methacholine between asthmatics, patients with aller…

1998

The aim of this study was to detect differences in maximal response and position of the concentration-response curves to methacholine between asthmatics and subjects with allergic rhinitis. A total of 228 adults (107 mild asthmatics, 96 allergic rhinitics and 25 healthy control subjects) were challenged with methacholine. The test was interrupted when FEV1 dropped by more than 40% or when the highest concentration of methacholine (200 mg ml-1) had been administered. Concentration-response curves were characterized by their PC20 (concentration of methacholine that produced 20% fall in FEV1 = airway sensitivity), and if possible, by their EC50 (concentration of methacholine that produced 50% …

Serum low density lipoprotein subclasses in asthma

2013

Summary Background The levels of serum low-density lipoproteins (LDL) have been implicated in the inflammatory cascade in a murine model of asthma. Recent findings suggest that LDL may modulate the inflammatory state of the asthmatic airways in humans. Objective We explored whether LDL subclasses are associated with the occurrence and severity of asthma. Methods 24 asthmatics (M/F: 11/13) and 24 healthy individuals, with normal BMI and absence of metabolic syndrome, matched for age and gender. Serum concentrations of LDL subclasses were distributed as seven bands (LDL-1 and -2 defined as large, least pro-inflammatory LDL, and LDL-3 to −7 defined as small, most pro-inflammatory LDL), using t…

Understanding the role of saliva in aroma release from wine by using static and dynamic headspace conditions.

2014

The aim of this work was to determine the role of saliva in wine aroma release by using static and dynamic headspace conditions. In the latter conditions, two different sampling points (t = 0 and t = 10 min) corresponding with oral (25.5 °C) and postoral phases (36 °C) were monitored. Both methodologies were applied to reconstituted dearomatized white and red wines with different nonvolatile wine matrix compositions and a synthetic wine (without matrix effect). All of the wines had the same ethanol concentration and were spiked with a mixture of 45 aroma compounds covering a wide range of physicochemical characteristics at typical wine concentrations. Two types of saliva (human and artifici…

Unstimulated salivary flow rate, pH and buffer capacity of saliva in healthy volunteers

2004

Objectives: To assess the salivary flow rate, pH, and buffer capacity of healthy volunteers, and their relationships with age, gender, obesity, smoking, and alcohol consumption, and to establish the lower-end value of normal salivary flow (oligosialia). Methods: A prospective study was conducted in 159 healthy volunteers (age > 18 years, absence of medical conditions that could decrease salivary flow). Unstimulated whole saliva was collected during ten minutes, and salivary flow rate (ml/min), pH, and bicarbonate concentration (mmol/l) were measured using a Radiometer ABL 520. The 5 percentile of salivary flow rate and bicarbonate concentration was considered the lower limit of normality. R…

Methodological considerations to determine the effect of exercise on brain-derived neurotrophic factor levels.

2015

Objectives: Physical exercise up-regulates brain-derived neurotrophic factor (BDNF) in the brain and blood. However, there is yet no consensus about the adequate blood processing conditions to standardize its assessment. We aimed to find a reliable blood sample processing method to determine changes in BDNF due to exercise. Design and methods: Twelve healthy university students performed an incremental cycling test to exhaustion. At baseline, immediately after exercise, and 30 and 60 min of recovery, venous blood was drawn and processed under different conditions, i.e. whole blood, serum coagulated for 10 min and 24 h, total plasma, and platelet-free plasma. BDNF concentration was measured …

Increased prostaglandin E2 concentrations and cyclooxygenase-2 expression in asthmatic subjects with sputum eosinophilia.

2003

Abstract Background Prostaglandin E 2 (PGE 2 ) is known to be produced within human airways, but it is not clear whether in airway diseases it can play a deleterious or a beneficial role. Recently it has been reported that PGE 2 can enhance eosinophil survival in vitro. Objective To evaluate whether the concentrations of PGE 2 in asthmatic airways correlate with the number of eosinophils and can be responsible for eosinophil-enhanced survival and to identify the cyclooxygenase isoform contributing to the synthesis of PGE 2 by cells present in asthmatic airways. Methods Reversed-phase high-performance liquid chromatography and/or specific radioimmunoassay was used to measure PGE 2 concentrat…