The role of aortic chemoreceptors during acute anemia

1984 ◽  
Vol 62 (5) ◽  
pp. 519-523 ◽  
Author(s):  
P. C. Szlyk ◽  
C. King ◽  
D. B. Jennings ◽  
S. M. Cain ◽  
C. K. Chapler
Keyword(s):  
Mean Value ◽  
Whole Body ◽  
Metabolic Responses ◽  
Limb Blood Flow ◽  
Acute Anemia ◽  
Control Value ◽  
Blood Exchange ◽  
Anesthetized Dogs ◽  
The Mean

The importance of aortic chemoreceptors in the circulatory and metabolic responses during acute anemia was studied in anesthetized dogs. Data were obtained from nine dogs in which the aortic chemoreceptors were surgically denervated prior to induction of anemia, and from seven sham-operated dogs. Cardiac output [Formula: see text], limb blood flow [Formula: see text], limb and whole body oxygen uptake [Formula: see text] were determined at normal hematocrit (Hct) and at 30 min of anemia (Hct = 13%) produced by isovolemic dextran-for-blood exchange. At 30 min of anemia, [Formula: see text] was increased from 91 to 186 mL∙kg−1∙min−1 (p < 0.01) and from 99 to 153 mL∙kg−1∙min−1 (p < 0.01) in the sham and denervated groups, respectively. The increase in [Formula: see text] during anemia was less (p < 0.05) in the aortic-denervated series. Limb flow was also increased during anemia in both groups (p < 0.01); the mean value of 89 mL∙kg−1∙min−1 in the denervated group was less than that of 130 mL∙kg−1∙min−1 observed in the sham animals (p < 0.05). Whole body [Formula: see text] decreased (p < 0.05) in the denervated group at 30 min of anemia; limb [Formula: see text] was maintained at the preanemic control value in both groups. The data indicate that during acute anemia the aortic chemoreceptors contribute to the increase in [Formula: see text].

Respiratory quotients of human kidney in vivo

1963 ◽  
Vol 18 (4) ◽  
pp. 815-817 ◽  
Author(s):  
Earl S. Barker ◽  
Archer P. Crosley ◽  
John K. Clark
Keyword(s):  
Human Subjects ◽  
Human Kidney ◽  
Mean Value ◽  
Whole Body ◽  
Mean Values ◽  
Anesthetized Dogs ◽  
The Mean ◽  
Urine Formation ◽  
Analytical Errors

Renal respiratory quotient (RQ) has been calculated from data collected in unanesthetized human subjects. In contrast to RQ recently reported on anesthetized dogs, these data do not indicate a mean value greater than 1. Under control conditions in 24 subjects, renal RQ calculated without special corrections averaged 0.88. Correcting for differences in blood flow between renal artery and vein due to urine formation the mean was 0.73, with 95% confidence limits 0.49–0.97. With alkaline urines an additional correction for urinary excretion of CO2 is advised. Excluding procedures known to alkalinize the urine, RQ values were similar in 46 observations after a variety of experimental procedures. Since both numerator and denominator of the ratio involve small differences between large values, small analytical errors can produce large changes indistinguishable from physiologic variation. Therefore mean values rather than individual observations are stressed. While such values in our data appear similar to RQ for other organs and the whole body, they do not preclude considerable anaerobic metabolism. Submitted on August 9, 1962

The role of aortic chemoreceptors during severe CO hypoxia

1985 ◽  
Vol 63 (5) ◽  
pp. 509-514 ◽  
Author(s):  
C. E. King ◽  
S. M. Cain ◽  
C. K. Chapler
Keyword(s):  
Carbon Monoxide ◽  
Blood Flow ◽  
Cardiac Output ◽  
Whole Body ◽  
Limb Blood Flow ◽  
Intact Group ◽  
Anesthetized Dogs ◽  
Dialysis Method

The importance of aortic chemoreceptors in the circulatory responses to severe carbon monoxide (CO) hypoxia was studied in anesthetized dogs. The aortic chemoreceptors were surgically denervated in eight dogs prior to the induction of CO hypoxia, with nine other dogs serving as intact controls. Values for both whole body and hindlimb blood flow, vascular resistance, and O2 uptake were determined prior to and at 30 min of CO hypoxia in the two groups. Arterial O2 content was reduced 65% using an in situ dialysis method to produce CO hypoxia. At 30 min of hypoxia, cardiac output increased but limb blood flow remained at prehypoxic levels in both groups. This indicated that aortic chemoreceptor input was not necessary for the increase in cardiac output during severe CO hypoxia, nor for the diversion of this increased flow to nonmuscle tissues. Limb O2 uptake decreased during CO hypoxia in the aortic-denervated group but remained at prehypoxic levels in the intact group. The lower resting values for limb blood flow in the aortic-denervated animals required a greater level of O2 extraction to maintain resting O2 uptake. When CO hypoxia was superimposed upon this compensation, an O2 supply limitation occurred because the limb failed to vasodilate even as maximal levels for O2 extraction were approached.

Long-term dynamics and destruction of marsh vegetation in the Kolokolkova Bay of the Barents Sea

2012 ◽  
pp. 66-77 ◽  
Author(s):  
I. A. Lavrinenko ◽  
O. V. Lavrinenko ◽  
D. V. Dobrynin
Keyword(s):  
Species Composition ◽  
Plant Communities ◽  
Barents Sea ◽  
Mean Value ◽  
Marsh Vegetation ◽  
Composition And Structure ◽  
The Mean ◽  
Species Composition And Structure

The satellite images show that the area of marshes in the Kolokolkova bay was notstable during the period from 1973 up to 2011. Until 2010 it varied from 357 to 636 ha. After a severe storm happened on July 24–25, 2010 the total area of marshes was reduced up to 43–50 ha. The mean value of NDVI for studied marshes, reflecting the green biomass, varied from 0.13 to 0.32 before the storm in 2010, after the storm the NDVI decreased to 0.10, in 2011 — 0.03. A comparative analysis of species composition and structure of plant communities described in 2002 and 2011, allowed to evaluate the vegetation changes of marshes of the different topographic levels. They are fol­lowing: a total destruction of plant communities of the ass. Puccinellietum phryganodis and ass. Caricetum subspathaceae on low and middle marches; increasing role of halophytic species in plant communities of the ass. Caricetum glareosae vic. Calamagrostis deschampsioides subass. typicum on middle marches; some changes in species composition and structure of plant communities of the ass. Caricetum glareosae vic. Calamagrostis deschampsioides subass. festucetosum rubrae on high marches and ass. Parnassio palustris–Salicetum reptantis in transition zone between marches and tundra without changes of their syntaxonomy; a death of moss cover in plant communities of the ass. Caricetum mackenziei var. Warnstorfia exannulata on brackish coastal bogs. The possible reasons of dramatic vegetation dynamics are discussed. The dating of the storm makes it possible to observe the directions and rates of the succession of marches vegetation.

Seasonal trends in the stable isotopic composition of snow and meltwater runoff in a subarctic catchment at Okstindan, Norway

2004 ◽  
Vol 35 (2) ◽  
pp. 119-137 ◽  
Author(s):  
S.D. Gurney ◽  
D.S.L. Lawrence
Keyword(s):  
Isotopic Composition ◽  
Mean Value ◽  
Mean Values ◽  
Stable Isotopic Composition ◽  
Meltwater Runoff ◽  
Stable Isotopic ◽  
The Mean ◽  
The Difference ◽  
Δ18o And Δd

Seasonal variations in the stable isotopic composition of snow and meltwater were investigated in a sub-arctic, mountainous, but non-glacial, catchment at Okstindan in northern Norway based on analyses of δ18O and δD. Samples were collected during four field periods (August 1998; April 1999; June 1999 and August 1999) at three sites lying on an altitudinal transect (740–970 m a.s.l.). Snowpack data display an increase in the mean values of δ18O (increasing from a mean value of −13.51 to −11.49‰ between April and August), as well as a decrease in variability through the melt period. Comparison with a regional meteoric water line indicates that the slope of the δ18O–δD line for the snowpacks decreases over the same period, dropping from 7.49 to approximately 6.2.This change points to the role of evaporation in snowpack ablation and is confirmed by the vertical profile of deuterium excess. Snowpack seepage data, although limited, also suggest reduced values of δD, as might be associated with local evaporation during meltwater generation. In general, meltwaters were depleted in δ18O relative to the source snowpack at the peak of the melt (June), but later in the year (August) the difference between the two was not statistically significant. The diurnal pattern of isotopic composition indicates that the most depleted meltwaters coincide with the peak in temperature and, hence, meltwater production.

Analysis of Red Cell Mass and Plasma Volume in Patients With Polycythemia

2005 ◽  
Vol 129 (1) ◽  
pp. 89-91 ◽  
Author(s):  
Mordechai Lorberboym ◽  
Naomi Rahimi-Levene ◽  
Helena Lipszyc ◽  
Chun K. Kim
Keyword(s):  
Body Weight ◽  
Plasma Volume ◽  
Cell Mass ◽  
Mean Value ◽  
Whole Body ◽  
Red Cell ◽  
Volume Data ◽  
Red Cell Mass ◽  
The Mean ◽  
Iodine 125

Abstract Context.—Polycythemia describes an increased proportion of red blood cells in the peripheral blood. In absolute polycythemia, there is increased red cell mass (RCM) with normal plasma volume, in contrast with apparent polycythemia, in which there is increased or normal RCM and decreased plasma volume. In order to deliver the appropriate treatment it is necessary to differentiate between the two. Objective.—A retrospective analysis of RCM and plasma volume data are presented, with special attention to different methods of RCM interpretation. Design.—The measurements of RCM and plasma volume in 64 patients were compared with the venous and whole-body packed cell volume, and the incidence of absolute and apparent polycythemia was determined for increasing hematocrit levels. Measurements of RCM and plasma volume were performed using chromium 51–labeled red cells and iodine 125–labeled albumin, respectively. The measured RCM of each patient was expressed as a percentage of the mean expected RCM and was also defined as being within or outside the range of 2 SD of the mean. The results were also expressed in the traditional manner of mL/kg body weight. Results.—Twenty-one patients (13 women and 8 men) had absolute polycythemia. None of them had an increased plasma volume beyond 2 SD of the mean. When expressed according to the criteria of mL/kg body weight, 17 of the 21 patients had abnormally increased RCM, but 4 patients (19%) had a normal RCM value. Twenty-eight patients had apparent polycythemia. The remaining 15 patients had normal RCM and plasma volume. Conclusions.—The measurement of RCM and plasma volume is a simple and necessary procedure in the evaluation of polycythemia. In obese patients, the expression of RCM in mL/kg body weight lacks precision, considering that adipose tissue is hypovascular. The results of RCM are best described as being within or beyond 2 SD of the mean value.

The Excretion of Isotope in Urea and Ammonia for Estimating Protein Turnover in Man with [15N]Glycine

1981 ◽  
Vol 61 (2) ◽  
pp. 217-228 ◽  
Author(s):  
E. B. Fern ◽  
P. J. Garlick ◽  
Margaret A. McNurlan ◽  
J. C. Waterlow
Keyword(s):  
Protein Metabolism ◽  
Protein Turnover ◽  
Mean Value ◽  
Intravenous Dose ◽  
Whole Body ◽  
Body Protein ◽  
End Products ◽  
The Mean ◽  
15N Urea ◽  
Normal Adults

1. Four normal adults were given [15N]-glycine in a single dose either orally or intravenously. Rates of whole-body protein turnover were estimated from the excretion of 15N in ammonia and in urea during the following 9 h. The rate derived from urea took account of the [15N]urea retained in body water. 2. In postabsorptive subjects the rates of protein synthesis given by ammonia were equal to those from urea, when the isotope was given orally, but lower when an intravenous dose was given. 3. In subjects receiving equal portions of food every 2 h rates of synthesis calculated from ammonia were much lower than those from urea whether an oral or intravenous isotope was given. Comparison of rates obtained during the post-absorptive and absorptive periods indicated regulation by food intake primarily of synthesis when measurements were made on urea, but regulation primarily of breakdown when measurements were made on ammonia. 4. These inconsistencies suggest that changes in protein metabolism might be assessed better by correlating results given by different end-products, and it is suggested that the mean value given by urea and ammonia will be useful for this purpose.

scholarly journals Role of Chemical Biomarkers in Prediction of Intra-Amniotic Infection in Cases with Preterm Premature Rupture of Membrane, Observational Study

2019 ◽  
Vol 3 (2) ◽  
Keyword(s):  
Interleukin 6 ◽  
Mean Value ◽  
Maternal Serum ◽  
P Value ◽  
Subclinical Infection ◽  
Premature Rupture ◽  
Cutoff Value ◽  
The Mean ◽  
Sensitivity Specificity

Introduction: Early recognition of subclinical intra-amniotic infection before development of clinical Chorioamnionitis dramatically improve neonatal outcome before affection of fetal neurological function. Objective: this study was conducted to evaluate the role of procalcitonin and interleukin-6 in early prediction of intrauterine infection in pregnant women with premature rupture of membranes. Methods: This observational prospective cohort study was conducted on 100 pregnant women with preterm premature rupture of membrane (PPROM), Patients were divided into 2 groups: Group I: with normal CRP and WBCs level. Group2: with subclinical infection which was detected by elevated WBCs count >15,000 c/mm3 and / or positive CRP. This group was divided into two groups (Group (II) and Group (III) according to development of Chorioamnionitis. follow up of these patients was done to detect the cutoff value of procalcitonin and interleukin-6 as a predictive indicator of clinical intra-amniotic infection in patients with premature rupture of membrane. Results: This study showed that the mean value of maternal serum PCT concentration was higher in patients with clinical infection than its concentration in patients without infection or with subclinical infection with P-value 0.0001 which is highly significant between the studied cases and with cutoff value was >0.67ng/ml, sensitivity, specificity, PPV, NPV was 88.7%, 42.9%, 79.7% and 60% respectively and the mean value of maternal serum IL-6 concentration was also higher in patients with clinical infection than its concentration in patients without infection or with subclinical infection with P-value 0.001which is highly significant between the studied cases and with cutoff value was >11.1pg/ ml, sensitivity, specificity, PPV, NPV was 67.9%, 61.9%, 81.8% and 43.3% respectively. Conclusion: maternal serum procalcitonin is a good predictor of clinical intra-amniotic infection with good sensitivity, specificity, PPV, NPV which is nearly good as CRP which is better than serum interleukin-6 regarding sensitivity

scholarly journals THE LUCK IN “TALENT VERSUS LUCK” MODELING

2020 ◽  
Vol 23 (03) ◽  
pp. 2050007
Author(s):  
SEAN ELVIDGE
Keyword(s):  
Mean Value ◽  
Maximum Amount ◽  
Random Numbers ◽  
Individual Parameter ◽  
Input Parameters ◽  
The Mean ◽  
Model Variability ◽  
The Impact ◽  
The Relationship

This paper further investigates the Talent versus Luck (TvL) model described by [Pluchino et al. Talent versus luck: The role of randomness in success and failure, Adv. Complex Syst. 21 (2018) 1850014] which models the relationship between ‘talent’ and ‘luck’ on the impact of an individuals career. It is shown that the model is very sensitive to both random sampling and the choice of value for the input parameters. Running the model repeatedly with the same set of input parameters gives a range of output values of over 50% of the mean value. The sensitivity of the inputs of the model is analyzed using a variance-based approach based upon generating Sobol sequences of quasi-random numbers. When using the model to look at the talent associated with an individual who has the maximum capital over a model run it has been shown that the choice for the standard deviation of the talent distribution contributes to 67% of the model variability. When investigating the maximum amount of capital returned by the model the probability of a lucky event at any given epoch has the largest impact on the model, almost three times more than any other individual parameter. Consequently, during the analysis of the model results one must keep in mind the impact that only small changes in the input parameters can have on the model output.

Effect of nitroglycerin on myocardial collateral conductance in awake dogs

1988 ◽  
Vol 254 (4) ◽  
pp. H751-H755
Author(s):  
S. Brazzamano ◽  
J. C. Rembert ◽  
J. C. Greenfield
Keyword(s):  
Blood Flow ◽  
Pressure Gradient ◽  
Collateral Circulation ◽  
Coronary Occlusion ◽  
Mean Value ◽  
Coronary Collateral Circulation ◽  
Control Value ◽  
Coronary Pressure ◽  
The Mean ◽  
Collateral Vessels

Conductance of the coronary collateral circulation during the course of two abrupt circumflex coronary occlusions (pre- and posttreatment with nitroglycerin) was measured in awake dogs approximately 2 wk after collateral vessels were stimulated to develop. The pressure gradient from the central aorta to the distal circumflex coronary artery was measured, and myocardial blood flow was determined by 9-microns radioactive microspheres at 30 s and 4 min after coronary occlusions. Collateral conductance was calculated as mean collateral blood flow divided by the mean aorta-coronary pressure gradient. Before nitroglycerin, collateral conductance increased in all eight dogs from 30 s to 4 min by a mean value of 0.006 +/- 0.003 ml.min-1.g-1.mmHg-1. After nitroglycerin administration, the conductance at 30 s increased from the prenitroglycerin control value of 0.009 +/- 0.008 to 0.014 +/- 0.012 ml.min-1.g-1.mmHg-1, P less than 0.03. The mean change in conductance from 30 s to 4 min postnitroglycerin 0.003 +/- 0.003 ml.min-1.g-1.mmHg-1 was significantly less than during prenitroglycerin (P = 0.01). These data indicate that an increase in conductance during coronary occlusion occurs even in the immature collateral circulation. This effect presumably takes place in the arterial smooth muscle at the origin of the collateral vasculature.

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