Time course of end-expired carbon monoxide concentration is important in studies of cigarette smoking

1987 ◽  
Vol 73 (5) ◽  
pp. 553-555 ◽  
Author(s):  
G. Woodman ◽  
D. M. Wintoniuk ◽  
R. G. Taylor ◽  
S. W. Clarke
Keyword(s):  
Carbon Monoxide ◽  
Cigarette Smoking ◽  
Time Course ◽  
Slow Phase ◽  
Fast Phase ◽  
Carbon Monoxide Concentration ◽  
The Mean

1. Fifteen asymptomatic habitual smokers each smoked one of their usual cigarettes, not having smoked for 2 h. End-expired carbon monoxide concentration (EECO) was measured with an Ecolyzer 2000 series analyser before smoking (pre-S value), 1 min after finishing smoking (post-S value) and then at intervals up to 1 h. 2. The mean EECO boost (increase) over all subjects declined biphasically after smoking, with an initial fast phase from 1 to 5 min, and then a slow phase from 5 to 60 min. EECO fell by as much in the first 5 min as in the next hour. 3. Post-S EECO was related to pre-S EECO (r = 0.89, P < 0.001), but EECO boost was not related to pre-S (r = 0.00). EECO boost was unaffected by the sampling manoeuvre. 4. EECO measurements in epidemiological and smoking studies should not be made for at least 5 min after a cigarette is finished

Fast-phase transvascular fluid flux and the Fahraeus effect

1987 ◽  
Vol 62 (4) ◽  
pp. 1513-1520 ◽  
Author(s):  
W. N. Richardson ◽  
D. Bilan ◽  
M. Hoppensack ◽  
L. Oppenheimer
Keyword(s):  
Mechanical Properties ◽  
Slow Rate ◽  
Time Course ◽  
Rate Of Change ◽  
Distributed Model ◽  
Slow Phase ◽  
Fluid Flux ◽  
Fast Phase ◽  
Constant Rate ◽  
Fahraeus Effect

Transvascular fluid flux was induced in six isolated blood-perfused canine lobes by increasing and decreasing hydrostatic inflow pressure (Pi). Fluid flux was followed against the change in concentration of an impermeable tracer (Blue Dextran) measured directly with a colorimetric device. The time course of fluid flux was biphasic with an initial fast transient followed by a slow phase. Hematocrit changes unrelated to fluid flux occurred due to the Fahraeus effect, and their contribution to the total color signal was subtracted to determine the rate of fast fluid flux (Qf). Qf was related to Pi to derive fast-phase conductance (Kf). Slow-phase Kf was calculated from the constant rate of change of lobe weight. For a mean change in Pi of 7 cmH2O, 40% of the color signal was due to fluid flux. Fast- and slow-phase Kf's were 0.86 +/- 0.15 and 0.27 +/- 0.05 ml X min-1. cmH2O–1 X 100 g dry wt-1. The fast-phase Kf is smaller than that reported for plasma-perfused lobes. Possible explanations discussed are the nature of the perfusate, the mechanical properties of the interstitium, and the slow rate of rise of the driving pressure at the filtration site on the basis of a distributed model of pulmonary vascular compliance.

Pre-steady-state phosphorylation and dephosphorylation of detergent-purified plasma-membrane Ca2+-ATPase

2002 ◽  
Vol 361 (2) ◽  
pp. 355-361 ◽  
Author(s):  
Luis M. BREDESTON ◽  
Alcides F. REGA
Keyword(s):  
Plasma Membrane ◽  
Steady State ◽  
Time Course ◽  
Slow Phase ◽  
Fast Phase ◽  
Lauryl Ether ◽  
Phosphorylation Reaction ◽  
Steady Level ◽  
Biexponential Kinetics ◽  
Acidic Phospholipids

Pre-steady-state phosphorylation and dephosphorylation of purified and phospholipid-depleted plasma-membrane Ca2+-ATPase (PMCA) solubilized in the detergent polyoxyethylene 10 lauryl ether were studied at 25°C. The time course of phosphorylation with ATP of the enzyme associated with Ca2+, probably the true phosphorylation reaction, showed a fast phase (kapp near 400s−1) followed by a slow phase (kapp = 23s−1). With asolectin or acidic phosphatidylinositol, the concentration of phosphoenzyme (EP) increased at as high a rate as before, passed through a maximum at 4ms and stabilized at a steady level that was approx. half that without lipids. Calmodulin (CaM) did not change the rate of the fast phase, accelerated the slow phase (kapp = 93s−1) and increased [EP] with small changes in the shape of the time course. Dephosphorylation was slow (kapp = 30s−1) and insensitive to CaM. Asolectin accelerated dephosphorylation, which followed biexponential kinetics with fast (kapp = 220s−1) and slow (kapp = 20s−1) components. CaM stimulated the fast component by nearly 50%. The results show that the behaviour of the PMCA is complex, and suggest that acidic phospholipids and CaM activate PMCA through different mechanisms. Acceleration of dephosphorylation seems relevant during activation of the PMCA by acidic phospholipids.

scholarly journals Two Temporal Phases of Light Adaptation in Retinal Rods

2002 ◽  
Vol 119 (2) ◽  
pp. 129-146 ◽  
Author(s):  
Peter D. Calvert ◽  
Victor I. Govardovskii ◽  
Vadim Y. Arshavsky ◽  
Clint L. Makino
Keyword(s):  
Binding Sites ◽  
Time Course ◽  
Light Adaptation ◽  
Dynamic Range ◽  
Continuous Illumination ◽  
Slow Phase ◽  
Fast Phase ◽  
Slow Adaptation ◽  
Adaptation Phase

Vertebrate rod photoreceptors adjust their sensitivity as they adapt during exposure to steady light. Light adaptation prevents the rod from saturating and significantly extends its dynamic range. We examined the time course of the onset of light adaptation in bullfrog rods and compared it with the projected onset of feedback reactions thought to underlie light adaptation on the molecular level. We found that adaptation developed in two distinct temporal phases: (1) a fast phase that operated within seconds after the onset of illumination, which is consistent with most previous reports of a 1–2-s time constant for the onset of adaptation; and (2) a slow phase that engaged over tens of seconds of continuous illumination. The fast phase desensitized the rods as much as 80-fold, and was observed at every light intensity tested. The slow phase was observed only at light intensities that suppressed more than half of the dark current. It provided an additional sensitivity loss of up to 40-fold before the rod saturated. Thus, rods achieved a total degree of adaptation of ∼3,000-fold. Although the fast adaptation is likely to originate from the well characterized Ca2+-dependent feedback mechanisms regulating the activities of several phototransduction cascade components, the molecular mechanism underlying slow adaptation is unclear. We tested the hypothesis that the slow adaptation phase is mediated by cGMP dissociation from noncatalytic binding sites on the cGMP phosphodiesterase, which has been shown to reduce the lifetime of activated phosphodiesterase in vitro. Although cGMP dissociated from the noncatalytic binding sites in intact rods with kinetics approximating that for the slow adaptation phase, this hypothesis was ruled out because the intensity of light required for cGMP dissociation far exceeded that required to evoke the slow phase. Other possible mechanisms are discussed.

Spatial orientation of the vestibular system: dependence of optokinetic after-nystagmus on gravity

1991 ◽  
Vol 66 (4) ◽  
pp. 1422-1439 ◽  
Author(s):  
M. J. Dai ◽  
T. Raphan ◽  
B. Cohen
Keyword(s):  
Time Course ◽  
The Body ◽  
Body Axis ◽  
Coronal Plane ◽  
Velocity Storage ◽  
Slow Phase ◽  
Optokinetic Stimulation ◽  
Stimulus Motion ◽  
Marquardt Algorithm ◽  
The Mean

1. Monkeys received optokinetic stimulation at 60 degrees/s about their yaw (animal vertical) and pitch (animal horizontal) axes, as well as about other head-centered axes in the coronal plane. The animals were upright or tilted in right-side-down positions with regard to gravity. The stimuli induced horizontal, vertical, and oblique optokinetic nystagmus (OKN). OKN was followed by optokinetic after-nystagmus (OKAN), which was recorded in darkness. 2. When monkeys were tilted, stimulation that generated horizontal or yaw axis eye velocity during OKN induced a vertical or pitch component of slow phase velocity during OKAN. This has been designated as "cross-coupling" of OKAN. Eigenvalues and eigenvectors associated with the system generating OKAN were found as a function of tilt. They were determined by use of the Levenberg-Marquardt algorithm to minimize the mean square error between the output of a model of OKAN and the data. 3. The eigenvector associated with yaw OKAN (yaw axis eigenvector) was maintained close to the spatial vertical regardless of the angle of tilt. The eigenvector associated with pitch OKAN (pitch axis eigenvector) was always aligned with the body axis. The data indicate that velocity storage can be modeled by a piecewise linear system, the structure of which is dependent on gravity and the yaw axis eigenvector, which tends to align with gravity. 4. Yaw axis eigenvectors were also determined by giving optokinetic stimulation about head-centered axes in the coronal plane with the animal in various angles of tilt. A technique using a spectral analysis of residuals was developed to estimate whether yaw and pitch OKAN slow phase velocities decayed concurrently at the same relative rate and over the same time course. The eigenvectors determined by this method were in agreement with those obtained by analyzing OKAN elicited by yaw OKN. 5. During yaw OKN with the animal in tilted positions, the mean vector of the ensuing nystagmus was closer to the body axis than to the spatial vertical. This suggests that there is suppression of the cross-coupled pitch component during OKN. The direction of the stimulus may be utilized to suppress components of velocity storage not coincident with the direction of stimulus motion. 6. There were similarities between the monkey eigenvectors and human perception of the spatial vertical, and the mean of eigenvectors for upward and downward eye velocities overlay human 1-g perceptual data.(ABSTRACT TRUNCATED AT 400 WORDS)

Inhaled smoke volume, puffing indices and carbon monoxide uptake in asymptomatic cigarette smokers

1986 ◽  
Vol 71 (4) ◽  
pp. 421-427 ◽  
Author(s):  
G. Woodman ◽  
S. P. Newman ◽  
D. Pavia ◽  
S. W. Clarke
Keyword(s):  
Carbon Monoxide ◽  
Inert Gas ◽  
Cigarette Smokers ◽  
Carbon Monoxide Concentration ◽  
Puff Volume ◽  
The Mean ◽  
Subject Difference ◽  
Expired Air

1. Nine asymptomatic smokers each smoked one cigarette of their usual brand on four separate occasions. 2. The inhaled smoke volume was measured by tracing the smoke with the inert gas 81Krm. Puffing indices were recorded by using an electronic smoking analyser and flowhead/cigarette holder. The expired air carbon monoxide concentration was measured immediately before and within 5 min of finishing smoking. 3. The inhaled smoke percentage (total inhaled smoke volume/total puff volume) averaged 46% to 85% in different subjects. 4. Neither the mean inhaled smoke volume per puff nor the total inhaled smoke volume per cigarette was significantly correlated with any of the puffing indices. 5. Smokers took significantly smaller and shorter puffs, left longer between puffs and inhaled less smoke as the cigarette was smoked (P < 0.01), although the proportion of the puff which was subsequently inhaled did not change significantly. 6. There was no significant intra-subject difference in any index from one visit to another.

scholarly journals Carbon monoxide concentration in donated blood: relation to cigarette smoking and other sources

Transfusion ◽  
2009 ◽  
Vol 49 (2) ◽  
pp. 347-353 ◽  
Author(s):  
Anna-Maja Åberg ◽  
Birgitta Nilsson Sojka ◽  
Ola Winsö ◽  
Pernilla Abrahamsson ◽  
Göran Johansson ◽  
...  
Keyword(s):  
Carbon Monoxide ◽  
Cigarette Smoking ◽  
Carbon Monoxide Concentration ◽  
Donated Blood

scholarly journals The reaction of fully reduced cytochrome c oxidase with oxygen studied by flow-flash spectrophotometry at room temperature. Evidence for new pathways of electron transfer

1984 ◽  
Vol 218 (3) ◽  
pp. 913-921 ◽  
Author(s):  
B C Hill ◽  
C Greenwood
Keyword(s):  
Cytochrome C ◽  
Cytochrome C Oxidase ◽  
Time Course ◽  
Visible Region ◽  
Slow Phase ◽  
Second Phase ◽  
Difference Spectra ◽  
Fast Phase ◽  
O2 Concentration ◽  
Sensitive Phase

Absorption changes during the O2 reaction of reduced bovine cytochrome c oxidase were investigated by the rapid-reaction technique of flow-flash spectrophotometry in the Soret, visible and near-i.r. spectral regions. New features in the time courses of absorption change were observed relative to the earlier findings reported by Greenwood & Gibson [(1967) J. Biol. Chem. 242, 1782-1787]. These new features arise in the Soret and near-i.r. regions and allow the reaction to be described at all wavelengths as a composite of three exponential processes. There is a rapid O2-sensitive phase detectable in the Soret and visible region. The second phase has a rate that is somewhat less dependent on O2 concentration than is the fastest phase rate and is detectable in all three spectral regions. The rate of the third phase is almost independent of the O2 concentration and is also detectable in all spectral regions. Analysis of the three phases gives their rates and absorption amplitudes. The fast phase reaches a rate of 2.5 × 10(4) s-1 at the highest O2 concentration available at 20 degrees C, whereas the phase of intermediate rate is limited at a value of 7 × 10(3) s-1 and the slow phase rate is limited at 700 s-1. The ratios of the kinetic difference spectra for the fast phase and the slow phase do not correspond to the spectra of the individual haem centres. A branched mechanism is advanced that is able to reconcile the kinetic and static difference spectra. This mechanism suggests that some of the cytochrome a is oxidized along with cytochrome a3 in the initial O2-sensitive phase. In addition, the model requires that CuA is oxidized heterogeneously. This fits with the complex time course of oxidation observed at 830 nm while retaining CuA as virtually the sole contributor to absorbance at this wavelength.

Recovery from dynamic exercise

1995 ◽  
Vol 268 (6) ◽  
pp. H2311-H2320 ◽  
Author(s):  
R. E. Williams ◽  
S. M. Horvath
Keyword(s):  
Exercise Intensity ◽  
Time Course ◽  
Minute Ventilation ◽  
Dynamic Exercise ◽  
Slow Phase ◽  
Co2 Uptake ◽  
Exercise Tests ◽  
Fast Phase ◽  
Baseline Levels ◽  
Minimal Information

Minimal information is available on the basic interactions within the metabolic and cardiovascular systems during recovery from exercise. Nine men participated in three experiments: one control and two cost-equivalent (52 liters O2) exercise tests of 30 (EX30) and 45 (EX45) min. Exercise intensities were adjusted accordingly. During recovery, all parameters reestablished baseline levels within 10 min, except for heart rate (30 min). Correlations for each parameter for EX30 and EX45 were obtained by evaluating each subject's exercise cost and recovery "payback." A split, two-factor analysis of variance was run separately on the "fast" (minutes 1-7) and "slow" (minutes 10-60) phases of recovery to determine if the time course of recovery was related to exercise intensity. It was concluded that for a work cost of approximately 300 kcal, 1) the slow phase of recovery was unaffected by the exercise intensity, 2) the fast phase of cardiovascular recovery was unaffected by exercise intensity while minute ventilation and O2 and CO2 uptake were affected, and 3) cardiac output and the ventilatory equivalents for O2 and CO2 correlated well between work cost and recovery payback.

scholarly journals METABOLIC CONTROL OF LUMINESCENCE IN ISOLATED PHOTOPHORES OF PORICHTHYS: EFFECTS OF GLUCOSE ON OXYGEN CONSUMPTION AND LUMINESCENCE

1993 ◽  
Vol 181 (1) ◽  
pp. 279-293
Author(s):  
J. Mallefet ◽  
F. Baguet
Keyword(s):  
Oxygen Consumption ◽  
Time Course ◽  
Light Emission ◽  
Potassium Cyanide ◽  
Cellular Respiration ◽  
Slow Phase ◽  
Light Reaction ◽  
Fast Phase ◽  
Light Production ◽  
Rate Of Oxygen Consumption

1. Basal oxygen consumption of isolated photophores from Porichthys sp. at rest, i.e. without light emission, increased significantly from 0.101+/− 0.021 nmol min-1 to 0.173+/−0.016 nmol min-1 in response to the addition of 5.5 mmol l-1 glucose. 2. 5.5 mmol l-1 glucose pretreatment modified the time course of the two phases of adrenaline-induced luminescence; an increase in oxygen consumption was observed during the fast phase of light production but a decrease occurred during the slow phase of luminescence. 3. Pretreatment of isolated photophores with 5.5 mmol l-1 glucose totally inhibited the light emission induced by 1 mmol l-1 potassium cyanide. With this treatment, the respiration rate decreased progressively and after 40 min reached a value not significantly different from zero. 4. Even after blockage of cellular respiration by cyanide, an increase in the rate of oxygen consumption was observed during the fast adrenaline- induced luminescence. 5. Glucose utilisation by glycolysis or by oxidative metabolism may provide energy to an inhibitory mechanism that maintains the photophores in a non- luminescent state. 6. We suggest that the oxygen consumed during the fast phase of adrenaline luminescence could represent the activity of an extramitochondrial oxidative pathway involved in the light reaction.

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