The Measurement of Bidirectional Sodium Fluxes across the Intestinal Wall in Man Using Whole Gut Perfusion

1973 ◽  
Vol 44 (3) ◽  
pp. 267-278 ◽  
Author(s):  
A. H. G. Love ◽  
J. E. Rohde ◽  
M. E. Abrams ◽  
N. Veall
Keyword(s):  
Blood Plasma ◽  
Plasma Flow ◽  
Normal Subjects ◽  
Field Studies ◽  
Intestinal Wall ◽  
Perfusion Technique ◽  
Tracer Studies ◽  
Sodium Transfer ◽  
Recovered Material ◽  
Kinetics Of

1. Double-tracer studies have been carried out in order to investigate the validity of a whole-gut perfusion technique for the measurement of gut lumen-to-plasma and plasma-to-gut lumen sodium fluxes in man. 2. The use of two tracers permits differentiation between the unabsorbed orally administered sodium in the stools and the sodium which has been absorbed and resecreted. The latter is by no means negligible and may amount to some 30% of the recovered material. 3. The available data do not permit the calculation of the absolute values of the bidirectional fluxes without the introduction of some assumption concerning the reabsorption of the sodium which crosses from the plasma to the gut lumen. It is assumed here that this sodium is absorbed by the gut to the same extent as the orally administered material. Analysis of the kinetics of sodium transfer from mouth to stool direct and via the blood plasma in normal subjects and patients with diarrhoea provided experimental evidence confirming the correctness of this assumption. 4. In eleven normal volunteers the gut lumen-to-plasma flow of sodium averaged 13.0 mmol min−1, implying that the observed absorption averaging 1.65 mmol min−1 represents a relatively small imbalance between the bidirectional fluxes. Although one patient with post-gastrectomy dumping syndrome had high fluxes and another with malabsorption following gut resection gave low values, it is suggested that changes in the fluxes in the same patient are more significant than isolated observations on individuals. 5. Granted the validity of the primary assumption, a considerably simpler technique may be used for clinical and field studies which is sufficiently accurate for most purposes and employs a single tracer.

Description of a Simple Model for the Study of Bone Calcium Metabolism

1980 ◽  
Vol 19 (01) ◽  
pp. 11-15
Author(s):  
G. Roncari ◽  
L. Rapisardi ◽  
L. Conte ◽  
G. Pedroli
Keyword(s):  
Simple Model ◽  
Calcium Metabolism ◽  
Good Description ◽  
Radioactive Tracer ◽  
Normal Subjects ◽  
Bone Diseases ◽  
Compartment System ◽  
Bone Calcium ◽  
Finite Period ◽  
Kinetics Of

A simple model for the study of bone calcium metabolism is proposed. It describes the kinetics of a radioactive tracer in terms of an open single compartment system with an expanding volume for a finite period of time. In addition to the simplicity of the hypotheses introduced, the model is able to give a good description of the biological processes which regulate calcium kinetics. Moreover the functional parameters can be easily calculated, even just graphically. 15 normal subjects and 22 patients affected by various bone diseases were studied. The results were compared with those obtained by using the model proposed by Burkinshaw et al. and the method described by Reeve et al.

Abnormal Platelet Serotonin Uptake and Binding Sites in Myeloproliferative Disorders

1984 ◽  
Vol 51 (03) ◽  
pp. 349-353 ◽  
Author(s):  
C Caranobe ◽  
P Sié ◽  
F Fernandez ◽  
J Pris ◽  
S Moatti ◽  
...  
Keyword(s):  
Binding Sites ◽  
High Capacity ◽  
Specific Inhibitor ◽  
Myeloproliferative Disorders ◽  
Normal Subjects ◽  
Binding Data ◽  
Full Explanation ◽  
Number Of Binding Sites ◽  
5 Ht Uptake ◽  
Kinetics Of

SummaryA simultaneous investigation of the kinetics of serotonin (5 HT) uptake and of binding sites was carried out in the platelets of normal subjects and of 10 patients affected with various types of myeloproliferative disorders (MD). The 5 HT uptake was analysed according to the Lineweaver-Burk and the Eadie-Hofstee methods. With the two methods, the patient’s platelets exhibited a dramatic reduction of the Vi max and of the Km; in some patients the Eadie-Hofstee analysis revealed that a passive diffusion phenomenon is superimposed on the active 5 HT uptake at least for the higher concentration used. The binding data were analysed with the Scatchard method. Two classes of binding sites (high affinity - low capacity, low affinity - high capacity) were found in normal subjects and patients. Pharmacological studies with imipramine, a specific inhibitor of 5 HT uptake, suggested that both the sites are involved in 5 HT uptake. The number of both binding sites was significantly decreased in patient’s platelets while the affinity constants of these binding sites were not significantly reduced in comparison with those of the control subjects. No correlations were found between Vi max, Km and the number of binding sites. These results suggest that a reduction in the number of platelet membrane acceptors for 5 HT commonly occurs in myeloproliferative disorders but does not provide a full explanation of the uptake defect.

Kinetics of the Processes in a Nitrogen Plasma Flow with Carbon Admixture

2020 ◽  
Vol 58 (5) ◽  
pp. 671-680
Author(s):  
O. V. Korshunov ◽  
D. I. Kavyrshin ◽  
V. F. Chinnov
Keyword(s):  
Plasma Flow ◽  
Nitrogen Plasma ◽  
Kinetics Of

KINETICS OF INSULIN DISAPPEARANCE FROM PLASMA IN CORTISONE-TREATED NORMAL SUBJECTS

1987 ◽  
Vol 26 (5) ◽  
pp. 623-628 ◽  
Author(s):  
K. ELLEMANN ◽  
B. THORSTEINSSON ◽  
S. FUGLEBERG ◽  
B. FELDT-RASMUSSEN ◽  
O. O. ANDERSEN ◽  
...  
Keyword(s):  
Normal Subjects ◽  
Kinetics Of

Measurements of the jejunal unstirred layer in normal subjects and patients with celiac disease

1996 ◽  
Vol 270 (3) ◽  
pp. G487-G491 ◽  
Author(s):  
A. Strocchi ◽  
G. Corazza ◽  
J. Furne ◽  
C. Fine ◽  
A. Di Sario ◽  
...  
Keyword(s):  
Celiac Disease ◽  
Layer Thickness ◽  
Villous Atrophy ◽  
Normal Subjects ◽  
Unstirred Layer ◽  
Maximal Velocity ◽  
Normal Rat ◽  
Kinetics Of

Normal intestinal absorption of nutrients requires efficient luminal mixing to deliver solute to the brush border. Lacking such mixing, the buildup of thick unstirred layers over the mucosa markedly retards absorption of rapidly transported compounds. Using a technique based on the kinetics of maltose hydrolysis, we measured the unstirred layer thickness of the jejunum of normal subjects and patients with celiac disease, as well as that of the normal rat. The jejunum of humans and rats was perfused with varying maltose concentrations, and the apparent Michaelis constant (Km) and maximal velocity (Vmax) of maltose hydrolysis were determined from double-reciprocal plots. The true Km of intestinal maltase was determined on mucosal biopsies. Unstirred layer thickness was calculated from the in vivo Vmax and apparent Km and the in vitro Km of maltase. The average unstirred layer thickness of 11 celiac patients (170 micron) was seven times greater than that of 3 controls (25 micron). The unstirred layer of each celiac exceeded that of the controls. A variety of factors could account for the less efficient luminal stirring observed in celiacs. Although speculative, villous contractility could be an important stirring mechanism that would be absent in celiacs with villous atrophy. This speculation was supported by the finding of a relatively thick unstirred layer (mean: 106 micron) in rats, an animal that lacks villous contractility. Because any increase in unstirred layer slows transport of rapidly absorbed compounds, poor stirring appears to represent a previously unrecognized defect that could contribute to malabsorption in celiac disease and, perhaps, in other intestinal disorders.

Effect of 1,25-(OH)2D3 on jejunal absorption of magnesium in patients with chronic renal disease

1980 ◽  
Vol 238 (4) ◽  
pp. G349-G352 ◽  
Author(s):  
A. C. Schmulen ◽  
M. Lerman ◽  
C. Y. Pak ◽  
J. Zerwekh ◽  
S. Morawski ◽  
...  
Keyword(s):  
Vitamin D ◽  
Renal Disease ◽  
Chronic Renal Disease ◽  
Normal Subjects ◽  
Mean Value ◽  
Normal Serum ◽  
Perfusion Technique ◽  
Dihydroxyvitamin D3 ◽  
Jejunal Absorption ◽  
The Mean

These studies were performed to see if jejunal malabsorption of magnesium in patients with chronic renal disease was influenced by therapy with 1 alpha, 25-dihydroxyvitamin D3 [1,25-(OH)2D3; 2 microgram/day by mouth for 7 days]. This treatment restored normal serum concentrations of the vitamin D metabolite from 0.9 +/- 0.2 to 4.2 +/- 0.6 ng/dl. Jejunal absorption of magnesium, measured by a triple-lumen constant-perfusion technique, was enhanced in each of the seven patients by this therapy. The mean value rose from 0.04 +/- 0.02 to 0.13 +/- 0.02 mmol . 30 cm-1 . h-1. This last value is similar to the magnesium absorption rate in untreated normal subjects. These results demonstrate that magnesium absorption in the human jejunum is dependent on vitamin D, and they show that 1 alpha,25-dihydroxyvitamin D3 therapy in patients with chronic renal failure is associated with an enhanced jejunal absorption of magnesium.

A rheological study of the kinetics of coagulation in normal and hemophilic blood plasma

Biorheology ◽  
1979 ◽  
Vol 16 (6) ◽  
pp. 403-410 ◽  
Author(s):  
M.S. Kuntamukkula ◽  
L.V. McIntire ◽  
E.A. Natelson
Keyword(s):  
Blood Plasma ◽  
Rheological Study ◽  
Kinetics Of

Studying the Blood Plasma Flow past a Red Blood Cell with the Mathematical Method of Kelvin's Transformation

2014 ◽  
Vol 2 (1) ◽  
pp. 57-66
Author(s):  
Maria Hadjinicolaou ◽  
Eleftherios Protopapas
Keyword(s):  
Blood Cell ◽  
Blood Plasma ◽  
Stream Function ◽  
Plasma Flow ◽  
Red Blood Cell ◽  
Fluid Velocity ◽  
Prolate Spheroid ◽  
Mathematical Tool ◽  
Flow Past ◽  
Analytical Expressions

A mathematical tool, namely the Kelvin transformation, has been employed in order to derive analytical expressions for important hydrodynamic quantities, aiming to the understanding and to the study of the blood plasma flow past a Red Blood Cell (RBC). These quantities are the fluid velocity, the drag force exerted on a cell and the drag coefficient. They are obtained by employing the stream function ? which describes the Stokes flow past a fixed cell. The RBC, being a biconcave disk, has been modelled as an inverted prolate spheroid. The stream function is given as a series expansion in terms of Gegenbauer functions, which converge fast. Therefore we employ only the first term of the series in order to derive simple and ready to use analytical expressions. These expressions are important in medicine, for studying, for example the transportation of oxygen, or the drug delivery to solid tumors.

Peripheral muscle ergoreceptors and ventilatory response during exercise recovery in heart failure

1999 ◽  
Vol 276 (3) ◽  
pp. H913-H917 ◽  
Author(s):  
Noelle Francis ◽  
Alain Cohen-Solal ◽  
Damien Logeart
Keyword(s):  
Heart Failure ◽  
Chronic Heart Failure ◽  
Ventilatory Response ◽  
Normal Subjects ◽  
Exercise Recovery ◽  
Cuff Inflation ◽  
Half Time ◽  
Peripheral Muscle ◽  
Patients With Heart Failure ◽  
Kinetics Of

Recent studies have suggested that the increased ventilatory response during exercise in patients with chronic heart failure was related to the activation of muscle metaboreceptors. To address this issue, 23 patients with heart failure and 7 normal subjects performed arm and leg bicycle exercises with and without cuff inflation around the arms or the thighs during recovery. Obstruction slightly reduced ventilation and gas exchange variables at recovery but did not change the kinetics of recovery of these parameters compared with nonobstructed recovery: half-time of ventilation recovery was 175 ± 54 to 176 ± 40 s in patients and 155 ± 66 to 127 ± 13 s in controls ( P < 0.05, patients vs. controls, not significant within each group from baseline to obstructed recovery). We conclude that muscle metaboreceptor activation does not seem to play a role in the exertion hyperventilation of patients with heart failure.

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