scholarly journals Acute Altitude Acclimatization in Young Healthy Volunteers: Nocturnal Oxygenation Increases Over Time, Whereas Periodic Breathing Persists

2020 ◽  
Author(s):  
Jia-Der Ju ◽  
Cristian Zhang ◽  
Francis P. Sgambati ◽  
Lidia M. Lopez ◽  
Luu V. Pham ◽  
...  
Keyword(s):  
Healthy Volunteers ◽  
Periodic Breathing ◽  
Altitude Acclimatization ◽  
Over Time

scholarly journals Using Redox Potential as a Feasible Marker for Banked Blood Quality and the State of Oxidative Stress in Stored Red Blood Cells

2020 ◽  
Author(s):  
Rodney C Daniels ◽  
Hyesun Jun ◽  
Robertson D Davenport ◽  
Maryanne M Collinson ◽  
Kevin R Ward
Keyword(s):  
Oxidative Stress ◽  
Redox Potential ◽  
Red Blood Cells ◽  
Healthy Volunteers ◽  
Blood Cells ◽  
Storage Time ◽  
Cell Function ◽  
Venous Blood ◽  
Functional Changes ◽  
Over Time

Abstract Background Stored Red Blood Cells (RBCs) may undergo oxidative stress over time, with functional changes affecting critical tasks such as oxygen delivery. Central to these changes are oxidation-reduction (redox) reactions and the redox potential (RP) that must be maintained for proper cell function. RP imbalance can lead to oxidative stress that may contribute to storage lesions and transfusion-related morbidities. Direct measures of RP may allow for evaluation of erythrocyte quality and enable corrections of RP prior to transfusion. Methods Multiple random RBC segments were tested, ranging in age from 5 to 40 days at 5 day intervals. RP was recorded by measuring open circuit potential of RBCs using novel nanoporous gold electrodes with Ag/AgCl reference. RP measures were also performed on peripheral venous blood samples from 10 healthy volunteers. RP measures were compared between groups of aged RBCs, and with volunteer blood. Results Stored RBCs show time-dependent increases in RP. There were significant differences in Day 5 RP compared to all other groups (p≤0.005), Day 10-15 vs ages ≥ Day 20 (p≤0.025), Day 20-25 vs Day 40 (p=0.039), and all groups compared to healthy volunteers. RP became more positive over time suggesting ongoing oxidation as RBCs age. However, storage time alone does not predict the ultimate RP value measured from a given unit.Conclusions There are significant differences in RP between freshly stored RBCs and all others, with RP becoming more positive over time. However, storage time alone does not predict RP, indicating RP screening may be important independent of storage time and may serve as a marker of RBC quality and state of oxidative stress. RP measurements may also provide a target by which to restore RP balance in aged pRBCs, improving their clinical effectiveness while reducing associated morbidities.

scholarly journals The Effect of Hyperinsulinaemic Euglycaemia on Myocardial Blood Flow Reserve in Healthy Volunteers Over Time

2016 ◽  
Vol 25 ◽  
pp. S278
Author(s):  
M. Nam ◽  
T. Stanton ◽  
A. Russell ◽  
I. Hickman ◽  
C. Askew ◽  
...  
Keyword(s):  
Blood Flow ◽  
Myocardial Blood Flow ◽  
Healthy Volunteers ◽  
Flow Reserve ◽  
Myocardial Blood Flow Reserve ◽  
Over Time

scholarly journals Variability of cytochrome P450 1A2 activity over time in young and elderly healthy volunteers

2001 ◽  
Vol 52 (5) ◽  
pp. 601-604 ◽  
Author(s):  
T. Simon ◽  
L. Becquemont ◽  
B. Hamon ◽  
E. Nouyrigat ◽  
Y. Chodjania ◽  
...  
Keyword(s):  
Cytochrome P450 ◽  
Healthy Volunteers ◽  
Cytochrome P450 1A2 ◽  
Over Time

Altitude acclimatization: influence on periodic breathing and chemoresponsiveness during sleep

1987 ◽  
Vol 63 (1) ◽  
pp. 401-412 ◽  
Author(s):  
D. P. White ◽  
K. Gleeson ◽  
C. K. Pickett ◽  
A. M. Rannels ◽  
A. Cymerman ◽  
...  
Keyword(s):  
Sea Level ◽  
Eye Movement ◽  
Ventilatory Response ◽  
Periodic Breathing ◽  
Rapid Eye Movement ◽  
Initial Exposure ◽  
Ventilatory Responses ◽  
Altitude Acclimatization ◽  
Hypercapnic Ventilatory Response ◽  
Arterial O2 Saturation

Although the influence of altitude acclimatization on respiration has been carefully studied, the associated changes in hypoxic and hypercapnic ventilatory responses are the subject of controversy with neither response being previously evaluated during sleep at altitude. Therefore, six healthy males were studied at sea level and on nights 1, 4, and 7 after arrival at altitude (14,110 ft). During wakefulness, ventilation and the ventilatory responses to hypoxia and hypercapnia were determined on each occasion. During both non-rapid-eye-movement and rapid-eye-movement sleep, ventilation, ventilatory pattern, and the hypercapnic ventilatory response (measured at ambient arterial O2 saturation) were determined. There were four primary observations from this study: 1) the hypoxic ventilatory response, although similar to sea level values on arrival at altitude, increased steadily with acclimatization up to 7 days; 2) the slope of the hypercapnic ventilatory response increased on initial exposure to a hypoxic environment (altitude) but did not increase further with acclimatization, although the position of this response shifted steadily to the left (lower PCO2 values); 3) the sleep-induced decrements in both ventilation and hypercapnic responsiveness at altitude were equivalent to those observed at sea level with similar acclimatization occurring during wakefulness and sleep; and 4) the quantity of periodic breathing during sleep at altitude was highly variable and tended to occur more frequently in individuals with higher ventilatory responses to both hypoxia and hypercapnia.

scholarly journals Characteristics of exhaled particle production in healthy volunteers: possible implications for infectious disease transmission

F1000Research ◽  
2013 ◽  
Vol 2 ◽  
pp. 14 ◽  
Author(s):  
Fatima Wurie ◽  
Olivier Le Polain de Waroux ◽  
Matthew Brande ◽  
Wesley DeHaan ◽  
Katherine Holdgate ◽  
...  
Keyword(s):  
Healthy Volunteers ◽  
Respiratory Infection ◽  
Disease Transmission ◽  
Particle Production ◽  
Great Majority ◽  
Transmission Risk ◽  
Linear Regression Models ◽  
Tidal Breathing ◽  
High Production ◽  
Over Time

The size and concentration of exhaled particles may influence respiratory infection transmission risk. We assessed variation in exhaled particle production between individuals, factors associated with high production and stability over time.We measured exhaled particle production during tidal breathing in a sample of 79 healthy volunteers, using optical particle counter technology. Repeat measurements (several months after baseline) were obtained for 37 of the 79 participants.   Multilevel linear regression models of log transformed particle production measures were used to assess risk factors for high production.  Stability between measurements over time was assessed using Lin’s correlation coefficients.Ninety-nine percent of expired particles were <1μm in diameter. Considerable variation in exhaled particle production was observed between individuals and within individuals over time. Distribution of particle production was right skewed.  Approximately 90% of individuals produce <150 particles per litre in normal breathing.  A few individuals had measurements of over 1000 particles per litre (maximum 1456). Particle production increased with age (p<0.001) and was associated with high tree pollen counts. Particle production levels did not remain stable over time [rho 0.14 (95%CI -0.10, 0.38, p=0.238)].Sub-micron particles conducive to airborne rather than droplet transmission form the great majority of exhaled particles in tidal breathing. There is a high level of variability between subjects but measurements are not stable over time. Production increases with age and may be influenced by airway inflammation caused by environmental irritants. Further research is needed to determine whether the observed variations in exhaled particle production affect transmission of respiratory infection.

Reproducible activation in BA2, 1 and 3b associated with texture discrimination in healthy volunteers over time

NeuroImage ◽  
2008 ◽  
Vol 39 (1) ◽  
pp. 40-51 ◽  
Author(s):  
Leeanne M. Carey ◽  
David F. Abbott ◽  
Gary F. Egan ◽  
Geoffrey A. Donnan
Keyword(s):  
Healthy Volunteers ◽  
Texture Discrimination ◽  
Over Time

P.1.c.001 Acute psychomotor, memory and subjective effects of MDMA and THC (co-) administration over time in healthy volunteers

2010 ◽  
Vol 20 ◽  
pp. S235-S236
Author(s):  
G. Dumont ◽  
J. van Hasselt ◽  
M. de Kam ◽  
J. van Gerven ◽  
D. Touw ◽  
...  
Keyword(s):  
Healthy Volunteers ◽  
Subjective Effects ◽  
Over Time
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