Filtration coefficient in cat hindlimb using protein concentration changes

1989 ◽  
Vol 256 (1) ◽  
pp. H186-H194 ◽  
Author(s):  
P. D. Watson ◽  
M. B. Wolf
Keyword(s):  
Protein Concentration ◽  
Venous Pressure ◽  
Filtration Coefficient ◽  
Volume Changes ◽  
Vascular Volume ◽  
Perfusate Flow ◽  
Wide Range ◽  
Concentration Changes ◽  
The Difference ◽  
Pentobarbital Sodium Anesthesia

The maximum value of capillary filtration coefficient (CFC) in maximally vasodilated cat skeletal muscle is disputed. It was hypothesized that the wide range of reported values was caused by the inability of gravimetric and volumetric measurements of tissue volume to separate transcapillary filtration from vascular volume changes. Consequently, we developed a method of measuring filtration rates from changes in venous protein concentration using Evan's blue-labeled albumin in the isolated hindlimb (pentobarbital sodium anesthesia). The filtration coefficient (PFFC) calculated from these filtration rates after a step in venous pressure should not be influenced by vascular volume changes. When the perfusate flow rate through the hindlimb was greater than 15 ml.min-1.100 g muscle-1, PFFC was 0.0085 +/- 0.0015 (SD, n = 8) ml.min-1.mmHg-1.100 g muscle-1. PFFC was observed to be unvarying from 1 to 12 min after the venous pressure elevation, in contrast to CFC values, which fall during the same period. It is argued that the difference between CFC and PFFC values is caused by vascular volume changes.

Location and mechanisms of pulmonary vascular volume changes

1986 ◽  
Vol 60 (2) ◽  
pp. 402-409 ◽  
Author(s):  
C. A. Dawson ◽  
D. A. Rickaby ◽  
J. H. Linehan
Keyword(s):  
Venous Pressure ◽  
Substantial Effect ◽  
Storage Site ◽  
Constant Flow ◽  
Alveolar Pressure ◽  
Volume Changes ◽  
Vascular Volume ◽  
Vessel Volume ◽  
The Difference ◽  
Lung Lobes

We examined the influence of changing outflow pressure, P out, on the vascular and extravascular volumes (QV and QEV, respectively, as measured by indicator dilution) and on the outflow occlusion pressures in isolated dog lung lobes perfused with constant flow. Changing P out had a substantial effect on QV, but not on QEV, whether P out was less than or greater than alveolar pressure, PA. Since QEV did not change with QV, recruitment of previously unperfused vessels did not appear to contribute substantially to the increases in QV when P out was increased. The rapid jump in P out immediately following outflow occlusion was virtually independent of the difference between PA and P out suggesting that the alveolar vessels were an important volume storage site when P out was low relative to PA. We conclude that, over a certain range of pressures, alveolar vessel volume can be controlled by venous pressure even when the change in venous pressure has little effect on arterial pressure (zone 2). Further, we conclude that in zone 3 and within the transition from zone 2 to zone 3 increases in the intralobar blood volume occurring within the alveolar vessels may not require recruitment in the sense of opening of previously unperfused vessels.

Skeletal Muscle Vascular Volume Changes With Increased Venous Pressure

1976 ◽  
Vol 13 (4) ◽  
pp. 222-237 ◽  
Author(s):  
Carleton H. Baker ◽  
Richard P. Menninger ◽  
Robert E. Schoen ◽  
Truitt Sutton
Keyword(s):  
Skeletal Muscle ◽  
Venous Pressure ◽  
Volume Changes ◽  
Vascular Volume

Effects of elevated venous pressure on capillary permeability in cat hindlimbs

1989 ◽  
Vol 257 (6) ◽  
pp. H2025-H2032 ◽  
Author(s):  
M. B. Wolf ◽  
L. P. Porter ◽  
P. D. Watson
Keyword(s):  
Protein Concentration ◽  
Capillary Permeability ◽  
Venous Pressure ◽  
Filtration Coefficient ◽  
Solvent Drag ◽  
Theory Analysis ◽  
Plasma Protein Concentration ◽  
Fluid Filtration ◽  
Electrolyte Mixture ◽  
Initial Measurement

We investigated the effects of elevated venous pressure, Pv, (up to 140 mmHg) on the solvent drag reflection coefficient, sigma f, for protein and on the capillary filtration coefficient, CFC, in the isolated cat hindlimb perfused at constant flow. The perfusate contained 30% cat plasma and the remainder was a dialyzed albumin-electrolyte mixture. Cat red cells were added to a hematocrit of approximately 2%. sigma f was measured from the changes in hematocrit and plasma protein concentration (Integral-Mass Balance method) resulting from the fluid filtration caused by the Pv elevation. CFC was measured from the slope of the limb weight recording 2-4 min after the Pv elevation. sigma f decreased linearly from 0.807 (Pv less than 50 mmHg) to approximately 0.2 at 140 mmHg. CFC increased linearly from 0.0086 ml.min-1.mmHg-1.100 g-1 to about 0.04 over the same pressure range. A weight-independent filtration coefficient calculated from the change in hematocrit and a measurement of the initial perfusate volume gave comparable results, except at the very highest of pressures, where this coefficient was sometimes 20-40% less than CFC. Successive sigma f determinations at Pv at about 40 mmHg did not return to control after an initial measurement in which Pv was approximately 110 mmHg. Pore-theory analysis of the data suggests that the elevated Pv causes large pores to open as opposed to the stretching of small pores. Also, these large pores may remain open for a period of hours.

Vascular volume changes in the dog forelimb

1964 ◽  
Vol 206 (6) ◽  
pp. 1291-1298 ◽  
Author(s):  
Carleton H. Baker ◽  
L. J. O'Brien
Keyword(s):  
Blood Flow ◽  
Perfusion Pressure ◽  
Venous Pressure ◽  
Red Cells ◽  
Red Cell ◽  
Volume Changes ◽  
Vascular Volume ◽  
Three Stages ◽  
Control State ◽  
Concentration Curves

In an isolated dog forearm preparation perfusion pressure, venous pressure, and blood flow were determined. Blood flow and vascular volumes were estimated by arterial injection of red cells-Cr51 and albumin-I131. Measured blood flow agreed within ± 10% of that calculated from the indicator dilution. Vascular volume changes were determined from changes in limb weight. Measurements were made 1) during the control state, 2) during vasodilation with acetylcholine, and 3) after increasing the flow rate. The red cell-Cr51 volume averaged significantly less than that measured by the albumin-I131 at all three stages of the experiment. The ratio of the volumes (RBC-Cr51/albumin-I131) increased from 0.84 at the control to 0.93 in the dilated bed with elevated flow. Following vasodilation, the change in volume determined by weight change was significantly smaller than measured by the indicators. When flow was increased, the albumin-I131 measured a significantly smaller volume change than did the red cells-Cr51 or the weight. Three general types of time-concentration curves are described.

Effects of plasma- and cell-free perfusates on filtration coefficient of perfused canine lungs

1985 ◽  
Vol 58 (5) ◽  
pp. 1521-1527 ◽  
Author(s):  
B. Rippe ◽  
M. I. Townsley ◽  
A. E. Taylor
Keyword(s):  
Osmotic Pressure ◽  
Whole Blood ◽  
Plasma Proteins ◽  
Protein Concentration ◽  
Complete Removal ◽  
Systemic Circulation ◽  
Colloid Osmotic Pressure ◽  
Filtration Coefficient ◽  
Plasma Protein Concentration ◽  
The Difference

The filtration coefficient (Kf,c) of the microvessels in isolated dog lungs were studied for whole and diluted blood, whole and diluted plasma, Tyrode's solution, and Tyrode's plus dextran (4%, 63,000 mol wt) perfusates. When whole blood and plasma were diluted, Kf,c increased abruptly at a plasma protein concentration between 4 and 5 g/l, an effect which was not dependent on the erythrocyte mass. Both Tyrode's and Tyrode's plus dextran produced increases in Kf,c (60 and 30%, respectively). The difference in Kf,c measured between these latter perfusates was completely abolished when Kf,c were corrected for viscosity differences. Thus the pulmonary microvasculature responds similarly to the systemic circulation in that complete removal of plasma proteins from the perfusate increases Kf,c by 50%. This effect is independent of erythrocyte mass or colloid osmotic pressure of the perfusate, since perfusion with dextran solutions alone also increased Kf,c.

Tissue pressure and autoregulation in the dextran-perfused kidney

1959 ◽  
Vol 197 (4) ◽  
pp. 853-855 ◽  
Author(s):  
Lerner B. Hinshaw ◽  
Henry M. Ballin ◽  
Stacey B. Day ◽  
Curtis H. Carlson
Keyword(s):  
Arterial Pressure ◽  
Renal Artery ◽  
Flow Rate ◽  
Volume Changes ◽  
Homologous Blood ◽  
Tissue Pressure ◽  
Vascular Volume ◽  
Perfusate Flow ◽  
Perfusate Flow Rate ◽  
Autoregulation Of Flow

Experiments were performed on isolated dog kidneys alternately perfused with homologous blood and dextran. Renal artery pressure, tissue pressure, perfusate flow rate and vascular volume changes were measured as arterial pressures were progressively elevated. Marked increases in overall vascular resistance RA/F occurred in all dextran- and blood-perfused kidneys throughout the autoregulatory range. Results indicate that autoregulation of flow occurs in both blood- and dextran-perfused kidneys concurrent with increases in tissue pressure. Dextran- and blood-perfused kidneys show similar degrees of autoregulation when values are expressed in terms of increase in flow per unit rise of arterial pressure and compared to preautoregulation values.

Hepatic capacitance responses to changes in flow and hepatic venous pressure in dogs

1981 ◽  
Vol 240 (1) ◽  
pp. H18-H28 ◽  
Author(s):  
T. D. Bennett ◽  
C. F. Rothe
Keyword(s):  
Venous Pressure ◽  
Liver Volume ◽  
Portal Venous Flow ◽  
Volume Changes ◽  
Venous Outflow ◽  
Venous Flow ◽  
Hepatic Volume ◽  
Hepatic Venous Outflow ◽  
Volume Shift ◽  
The Difference

The effect of changes in inflow and hepatic venous pressure (Phv) on the hepatic vascular bed was studied in denervated, pump-perfused canine livers. Hepatic arterial, portal venous, and hepatic venous pressures and flows were continuously monitored as was the hepatic venous hematocrit (Hct). The hepatic venous outflow, which averaged 1179 +/- 356 (SD) ml x min-1 x kg tissue-1 at control conditions, was controlled by a servosystem set to keep Phv at the desired level. Hepatic volume changes (delta V) were determined by integration of the difference between hepatic inflow (Fin) and outflow (Fhv). Over the range of Phv of 0-15 mmHg, the delta V-to-delta Phv ratio (apparent compliance C) was linear; C = 19.8 ml x mmHg-1 x kg tissue-1. These increases in Phv caused transient and plateau increases in Hct of 1.26 and 0.42%/mmHg, respectively. Varying inflow over the range of 0-156% of control by changing hepatic arterial and/or portal venous flow(s) resulted in delta V of 0.066 ml/kg per ml x min-1 x kg tissue-1 change in flow. We conclude that changes in Fin as well as changes in Phv cause changes in liver volume; and that a significant fraction of the volume shift accompanying changes in Phv is due to transsinusoidal plasma movement.

Dextran and capillary filtration coefficient in cat hindlimb

1985 ◽  
Vol 248 (4) ◽  
pp. H452-H456
Author(s):  
P. D. Watson ◽  
M. B. Wolf
Keyword(s):  
Weight Gain ◽  
Venous Pressure ◽  
Filtration Coefficient ◽  
Constant Flow ◽  
Three Solutions ◽  
Capillary Filtration ◽  
Capillary Filtration Coefficient ◽  
The Difference ◽  
Dextran Solution ◽  
Measured Viscosity

To investigate the possible mechanisms through which dextran modifies capillary filtration coefficient (CFC), the effects of perfusion with a protein-free dextran solution were compared with those of perfusion with a Ringerlike solution. With the use of the isolated cat hindlimb, CFC was measured during perfusion at constant flow with three solutions, a control blood-albumin mixture, a Ringerlike solution called dialysate, and 3.7 g/dl dextran dissolved in dialysate. The solutions were warmed to 37-38 degrees C, bubbled with 95% O2-5% CO2, and contained 0.015 g/dl or more papaverine. CFC was calculated from the rate of limb weight gain following a step increase in venous pressure. Dextran perfusion increased CFC to 2.0 +/- 0.2 (SD, n = 8) times control, which was significantly less (P less than 0.001) than 3.1 +/- 0.6 (n = 8) times control previously reported for dialysate perfusion. The difference between the measured viscosity of dextran (1.35 cP) and dialysate (0.72) could account for this reduction. However, when a dialysate perfusion followed a dextran perfusion, CFC only increased to 2.3 +/- 0.4 (n = 8) times control. This value is also significantly less (P less than 0.01) than 3.1. This observation suggests 1) that dextran is retained within the transcapillary channel and 2) that dextran reduces CFC mainly by partially blocking the transcapillary channel rather than by increasing viscosity.

Comparative Effects of High-Tech Visual Scene Displays and Low-Tech Isolated Picture Symbols on Engagement From Students With Multiple Disabilities

2019 ◽  
Vol 50 (4) ◽  
pp. 693-702 ◽  
Author(s):  
Christine Holyfield ◽  
Sydney Brooks ◽  
Allison Schluterman
Keyword(s):  
Language Learning ◽  
Augmentative And Alternative Communication ◽  
Visual Analysis ◽  
Multiple Disabilities ◽  
Visual Scene ◽  
Future Research ◽  
High Tech ◽  
Single Subject ◽  
Wide Range ◽  
The Difference

Purpose Augmentative and alternative communication (AAC) is an intervention approach that can promote communication and language in children with multiple disabilities who are beginning communicators. While a wide range of AAC technologies are available, little is known about the comparative effects of specific technology options. Given that engagement can be low for beginning communicators with multiple disabilities, the current study provides initial information about the comparative effects of 2 AAC technology options—high-tech visual scene displays (VSDs) and low-tech isolated picture symbols—on engagement. Method Three elementary-age beginning communicators with multiple disabilities participated. The study used a single-subject, alternating treatment design with each technology serving as a condition. Participants interacted with their school speech-language pathologists using each of the 2 technologies across 5 sessions in a block randomized order. Results According to visual analysis and nonoverlap of all pairs calculations, all 3 participants demonstrated more engagement with the high-tech VSDs than the low-tech isolated picture symbols as measured by their seconds of gaze toward each technology option. Despite the difference in engagement observed, there was no clear difference across the 2 conditions in engagement toward the communication partner or use of the AAC. Conclusions Clinicians can consider measuring engagement when evaluating AAC technology options for children with multiple disabilities and should consider evaluating high-tech VSDs as 1 technology option for them. Future research must explore the extent to which differences in engagement to particular AAC technologies result in differences in communication and language learning over time as might be expected.

COMBINATORIAL POLYNOMIALLY COMPUTABLE CHARACTERISTICS OF SUBSTITUTIONS AND THEIR PROPERTIES

2020 ◽  
Vol 7 (2) ◽  
pp. 34-41
Author(s):  
VLADIMIR NIKONOV ◽  
◽  
ANTON ZOBOV ◽  
Keyword(s):  
Mathematical Expectation ◽  
Point Of View ◽  
Small Range ◽  
Computational Point ◽  
Wide Range ◽  
Bijective Function ◽  
The Difference ◽  
Element Base ◽  
Selection Of

The construction and selection of a suitable bijective function, that is, substitution, is now becoming an important applied task, particularly for building block encryption systems. Many articles have suggested using different approaches to determining the quality of substitution, but most of them are highly computationally complex. The solution of this problem will significantly expand the range of methods for constructing and analyzing scheme in information protection systems. The purpose of research is to find easily measurable characteristics of substitutions, allowing to evaluate their quality, and also measures of the proximity of a particular substitutions to a random one, or its distance from it. For this purpose, several characteristics were proposed in this work: difference and polynomial, and their mathematical expectation was found, as well as variance for the difference characteristic. This allows us to make a conclusion about its quality by comparing the result of calculating the characteristic for a particular substitution with the calculated mathematical expectation. From a computational point of view, the thesises of the article are of exceptional interest due to the simplicity of the algorithm for quantifying the quality of bijective function substitutions. By its nature, the operation of calculating the difference characteristic carries out a simple summation of integer terms in a fixed and small range. Such an operation, both in the modern and in the prospective element base, is embedded in the logic of a wide range of functional elements, especially when implementing computational actions in the optical range, or on other carriers related to the field of nanotechnology.

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