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7 records – page 1 of 1.

Assessment of cerebral autoregulation: the quandary of quantification.

https://arctichealth.org/en/permalink/ahliterature122399
Source
Am J Physiol Heart Circ Physiol. 2012 Sep 15;303(6):H658-71
Publication Type
Article
Date
Sep-15-2012
Author
Y C Tzeng
P N Ainslie
W H Cooke
K C Peebles
C K Willie
B A MacRae
J D Smirl
H M Horsman
C A Rickards
Author Affiliation
Cardiovascular Systems Laboratory, University of Otago, Wellington South, New Zealand. shieak.tzeng@otago.ac.nz
Source
Am J Physiol Heart Circ Physiol. 2012 Sep 15;303(6):H658-71
Date
Sep-15-2012
Language
English
Publication Type
Article
Keywords
Adult
Blood Flow Velocity
Blood pressure
British Columbia
Cerebrovascular Circulation
Exercise
Female
Fourier Analysis
Heart rate
Homeostasis
Humans
Hypercapnia - physiopathology
Hypocapnia - physiopathology
Linear Models
Male
Middle Cerebral Artery - physiopathology - ultrasonography
Models, Cardiovascular
New Zealand
Observer Variation
Prospective Studies
Regional Blood Flow
Reproducibility of Results
Respiration
Retrospective Studies
Supine Position
Texas
Tourniquets
Ultrasonography, Doppler, Pulsed
Ultrasonography, Doppler, Transcranial
Young Adult
Abstract
We assessed the convergent validity of commonly applied metrics of cerebral autoregulation (CA) to determine the extent to which the metrics can be used interchangeably. To examine between-subject relationships among low-frequency (LF; 0.07-0.2 Hz) and very-low-frequency (VLF; 0.02-0.07 Hz) transfer function coherence, phase, gain, and normalized gain, we performed retrospective transfer function analysis on spontaneous blood pressure and middle cerebral artery blood velocity recordings from 105 individuals. We characterized the relationships (n = 29) among spontaneous transfer function metrics and the rate of regulation index and autoregulatory index derived from bilateral thigh-cuff deflation tests. In addition, we analyzed data from subjects (n = 29) who underwent a repeated squat-to-stand protocol to determine the relationships between transfer function metrics during forced blood pressure fluctuations. Finally, data from subjects (n = 16) who underwent step changes in end-tidal P(CO2) (P(ET)(CO2) were analyzed to determine whether transfer function metrics could reliably track the modulation of CA within individuals. CA metrics were generally unrelated or showed only weak to moderate correlations. Changes in P(ET)(CO2) were positively related to coherence [LF: ß = 0.0065 arbitrary units (AU)/mmHg and VLF: ß = 0.011 AU/mmHg, both P
PubMed ID
22821992 View in PubMed
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[Effect of the combined single and multiple action of hypoxia, hypercapnia and cooling on the morphofunctional changes in the anterior lobe of the hypophysis in white rats]

https://arctichealth.org/en/permalink/ahliterature57327
Source
Fiziol Zh. 1975 Nov-Dec;21(6):783-6
Publication Type
Article

Effects of a 1-yr stay at altitude on ventilation, metabolism, and work capacity.

https://arctichealth.org/en/permalink/ahliterature50230
Source
J Appl Physiol. 1992 Nov;73(5):1749-55
Publication Type
Article
Date
Nov-1992
Author
T V Serebrovskaya
A A Ivashkevich
Author Affiliation
A.A. Bogomoletz Institute of Physiology, Kiev, Ukraine.
Source
J Appl Physiol. 1992 Nov;73(5):1749-55
Date
Nov-1992
Language
English
Publication Type
Article
Keywords
Adult
Altitude
Carbon Dioxide - metabolism
Exercise Test
Humans
Hypercapnia - physiopathology
Lactates - blood
Lactic Acid
Male
Metabolism - physiology
Oxygen consumption
Physical Endurance - physiology
Pulmonary Gas Exchange - physiology
Pyruvates - blood
Pyruvic Acid
Respiratory Function Tests
Respiratory Mechanics - physiology
Abstract
The hypoxic and hypercapnic ventilatory drive, gas exchange, blood lactate and pyruvate concentrations, acid-base balance, and physical working capacity were determined in three groups of healthy males: 17 residents examined at sea level (group I), 24 sea-level natives residing at 1,680-m altitude for 1 yr and examined there (group II), and 17 sea-level natives residing at 3,650-m altitude for 1 yr and examined there (group III). The piecewise linear approximation technique was used to study the ventilatory response curves, which allowed a separate analysis of slopes during the first phase of slow increase in ventilation and the second phase of sharp increase. The hypoxic ventilatory response for both isocapnic and poikilocapnic conditions was greater in group II and even greater in group III. The first signs of consciousness distortion in sea-level residents appeared at an end-tidal O2 pressure level (4.09 +/- 0.56 kPa) higher than that of temporary residents of middle (3.05 +/- 0.12) and high altitude (2.90 +/- 0.07). The hypercapnic response was also increased, although to a lesser degree. Subjects with the highest hypoxic respiratory sensitivity at high altitude demonstrated greater O2 consumption at rest, greater ventilatory response to exercise, higher physical capacity, and a less pronounced anaerobic glycolytic flux but a lower tolerance to extreme hypoxia. That is, end-tidal O2 pressure that caused a distortion of the consciousness was higher in these subjects than in those with lower hypoxic sensitivity. Two extreme types of adaptation strategy can be distinguished: active, with marked reactions of "struggle for oxygen," and passive, with reduced O2 metabolism, as well as several intermediate types.(ABSTRACT TRUNCATED AT 250 WORDS)
PubMed ID
1474047 View in PubMed
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[Human higher nervous activity during adaptation to moderate altitude].

https://arctichealth.org/en/permalink/ahliterature237913
Source
Zh Vyssh Nerv Deiat Im I P Pavlova. 1986 Jan-Feb;36(1):12-9
Publication Type
Article
Author
Iu L Maidikov
N V Makarenko
N V Kol'chenko
T V Serebrovskaia
V M Kienko
Source
Zh Vyssh Nerv Deiat Im I P Pavlova. 1986 Jan-Feb;36(1):12-9
Language
Russian
Publication Type
Article
Keywords
Adaptation, Physiological
Adolescent
Altitude
Anoxia - physiopathology
Attention - physiology
Higher Nervous Activity
Humans
Hypercapnia - physiopathology
Male
Memory, Short-Term - physiology
Psychomotor Performance - physiology
Reaction Time - physiology
Respiration
Russia
Ukraine
Urban Population
Abstract
26 practically healthy youths of 16-18 years old not adapted to the mountains earlier were investigated under the conditions of a plain (Kiev) and at the height of 2100 m and 3000 m above sea-level (Chegem). A stay under the conditions of moderate altitude for one month was found to favour amelioration of the characteristics of the functional lability (CFL) of the nervous system, information processing velocity, attention concentration and distribution, short-term memory volume, general subjective feeling as well as shortening the latent periods of visually-motor reactions. Large adaptive shifts of the CFL and more stable positive effect of mountain adaptation after returning to the plain were found in persons with initially high functional lability level in comparison to those with mean or lower values of CFL. Positive connection between the CFL and the degree of adaptive changes of external respiration was observed under the conditions of moderate altitude. Statistically significant connection of the CFL with the respiratory center sensitivity to hypercapnia was found rather than their correlation with the value of ventilatory response to acute hypoxia during gas mixtures respiration.
PubMed ID
2939656 View in PubMed
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Relative magnitude of vascular reactivity in the major arterioles of the retina.

https://arctichealth.org/en/permalink/ahliterature129511
Source
Microvasc Res. 2012 Mar;83(2):200-4
Publication Type
Article
Date
Mar-2012
Author
Mitra Sehi
Edmund Tsui
Richard Cheng
Jennifer Wan
Tien Wong
Stephanie Dorner
Joseph Fisher
Christopher Hudson
Author Affiliation
Bascom Palmer Eye Institute, Department of Ophthalmology, Miller School of Medicine, University of Miami, Palm Beach Gardens, FL, USA.
Source
Microvasc Res. 2012 Mar;83(2):200-4
Date
Mar-2012
Language
English
Publication Type
Article
Keywords
Adult
Arterioles - physiopathology
Blood Flow Velocity
Female
Hemodynamics
Humans
Hypercapnia - physiopathology
Hyperoxia - physiopathology
Laser-Doppler Flowmetry
Male
Microcirculation
Ontario
Prospective Studies
Regional Blood Flow
Retinal Vessels - physiopathology
Time Factors
Vasoconstriction
Vasodilation
Young Adult
Abstract
The relative magnitude of vascular reactivity to inhaled gas stimuli in the major retinal arterioles has not been systematically investigated. The purpose of this study was to compare the magnitude of retinal vascular reactivity in response to inhaled gas provocation at equivalent measurement sites in the superior-, and inferior-, temporal retinal arterioles (STA, ITA). One randomly selected eye of each of 17 healthy volunteers (age 24.4 ± 4.7) was prospectively enrolled. Volunteers were connected to a sequential gas delivery circuit and a computer-controlled gas blender (RespirActâ„¢, Thornhill Research Inc., Canada) and underwent an isocapnic hyperoxic challenge i.e. P(ET)O(2) of 500 mm Hg with P(ET)CO(2) maintained at 38 mm Hg during baseline and hyperoxia. Four retinal hemodynamic measurements were acquired using bi-directional laser Doppler velocimetry and simultaneous vessel densitometry (Canon Laser Blood Flowmeter, CLBF-100, Japan) at equivalent positions on the STA and ITA. Statistical analysis was performed using linear mixed-effect models. During the hyperoxic phase, the vessel diameter (STA p=0.004; ITA p=0.003), blood velocity (STA p0.05). The magnitude of retinal arteriolar vascular reactivity in response to isocapnic hyperoxic inhaled gas challenge was not significantly different between the STA and ITA. However, the correlation analysis did not reveal a significant relationship between the percentage changes in diameter, velocity and flow of the STA and ITA and did not demonstrate equal responses from the STA and ITA to gas provocation.
PubMed ID
22100560 View in PubMed
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Susceptibility to hypoxia and breathing control changes after short-term cold exposures.

https://arctichealth.org/en/permalink/ahliterature284319
Source
Pages 962-966 in N. Murphy and A. Parkinson, eds. Circumpolar Health 2012: Circumpolar Health Comes Full Circle. Proceedings of the 15th International Congress on Circumpolar Health, Fairbanks, Alaska, USA, August 5-10, 2012. International Journal of Circumpolar Health 2013;72 (Suppl 1):962-966
Publication Type
Article
Date
2013
  1 document  
Author
Kovtun LT
Voevoda MI.
Author Affiliation
Federal State Budgetary Institution
"Research Institute of Physiology and Fundamental Medicine", Siberian Branch, Russian Academy of Medical Sciences, Novosibirsk, Russia
Source
Pages 962-966 in N. Murphy and A. Parkinson, eds. Circumpolar Health 2012: Circumpolar Health Comes Full Circle. Proceedings of the 15th International Congress on Circumpolar Health, Fairbanks, Alaska, USA, August 5-10, 2012. International Journal of Circumpolar Health 2013;72 (Suppl 1):962-966
Date
2013
Language
English
Publication Type
Article
Digital File Format
Text - PDF
Physical Holding
University of Alaska Anchorage
Keywords
Adolescent
Adult
Body Temperature Regulation/physiology
Cold Temperature/adverse effects
Environmental Exposure/adverse effects
Humans
Hypercapnia/physiopathology
Hypoxia/physiopathology
Male
Respiration
Time Factors
Young Adult
Documents
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Ventilatory phenotypes among four strains of adult rats.

https://arctichealth.org/en/permalink/ahliterature49800
Source
J Appl Physiol. 2002 Sep;93(3):974-83
Publication Type
Article
Date
Sep-2002
Author
Matthew R Hodges
Hubert V Forster
Paula E Papanek
Melinda R Dwinell
Genevieve E Hogan
Author Affiliation
Department of Physiology, Medical College of Wisconsin, Wisconsin 53226, USA.
Source
J Appl Physiol. 2002 Sep;93(3):974-83
Date
Sep-2002
Language
English
Publication Type
Article
Keywords
Animals
Anoxia - physiopathology
Female
Hypercapnia - physiopathology
Male
Motor Activity - physiology
Phenotype
Rats
Rats, Inbred Strains - physiology
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, P.H.S.
Respiration
Respiratory physiology
Sex Characteristics
Species Specificity
Abstract
Our purpose in this study was to identify different ventilatory phenotypes among four different strains of rats. We examined 114 rats from three in-house, inbred strains and one outbred strain: Brown Norway (BN; n = 26), Dahl salt-sensitive (n = 24), Fawn-hooded Hypertensive (FHH: n = 27), and outbred Sprague-Dawley rats (SD; n = 37). We measured eupneic (room air) breathing and the ventilatory responses to hypoxia (12% O(2)-88% N(2)), hypercapnia (7% CO(2)), and two levels of submaximal exercise. Primary strain differences were between BN and the other strains. BN rats had a relatively attenuated ventilatory response to CO(2) (P 0.05), indicating that the metabolic rate during hypoxia decreased more in BN rats than in other strains. Another strain difference was in the frequency and timing components of augmented breaths, where FHH rats frequently differed from the other strains, and the BN rats had the longest expiratory time of the augmented breaths (probably secondary to the blunted CO(2) sensitivity). These strain differences not only provide insight into physiological mechanisms but also indicate traits (such as CO(2) sensitivity) that are genetically regulated. Finally, the data establish a foundation for physiological genomic studies aimed at elucidating the genetics of these ventilatory control mechanisms.
PubMed ID
12183493 View in PubMed
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7 records – page 1 of 1.