THE FATE OF 1,2-3H CORTEXOLONE IN MAN

1964 ◽  
Vol 47 (1) ◽  
pp. 165-176 ◽  
Author(s):  
R. De Hertogh ◽  
J. J. Hoet ◽  
F. Materazzi ◽  
E. Ekka
Keyword(s):  
Steady State ◽  
Production Rate ◽  
Open System ◽  
Specific Activity ◽  
Normal Subjects ◽  
Apparent Volume ◽  
Endogenous Production ◽  
Disappearance Curve ◽  
The Mean ◽  
Life Values

ABSTRACT 1,2-3H cortexolone was injected into normal subjects and the disappearance curve of the radioactive hormone in the plasma was determined. This follows a biexponential function, according to a digital computer analysis. The half-life values calculated for the first and the second components of the experimental curves are 4 and 24 min respectively. On the basis of a two compartment open system, in which the second compartment is assumed to be metabolically inactive, cortexolone spreads rapidly into an apparent volume of 19 l and more slowly into a total volume of 37 l. Endogenous production rate of cortexolone was estimated from the isotope dilution of the injected hormone as determined by measurement of the specific activity of urinary tetrahydrocortexolone. The mean production rate for 4 normal subjects was calculated to be 1100 μg per day. From these data the size of the endogenous pool of cortexolone was calculated. This averages 9.3 and 9.2 μg for the first and second compartments respectively. The experiments are discussed with regard to a possible disturbance in the steady state by the amount of cortexolone injected.

Theory of production rate calculations in steady and non-steady states and its application to glucose metabolism

1992 ◽  
Vol 262 (6) ◽  
pp. E779-E790 ◽  
Author(s):  
J. A. Jacquez
Keyword(s):  
Steady State ◽  
Experimental Design ◽  
Specific Activity ◽  
Glucose Production ◽  
Central Compartment ◽  
Correct Equation ◽  
Endogenous Production ◽  
Correction Terms ◽  
Theory Of Production ◽  
Constant Specific Activity

I present a review and synthesis of the basic theory, steady state, and non-steady state for the calculation of metabolite production rates for systems that have a central well-mixed compartment that is the site of tracer input and sampling. The theory is then applied to the calculation of glucose production. If the only inputs are into the central compartment, an experimental design that involves varying tracer infusion rates to maintain constant specific activity in the central compartment and the same constant specific activity in the peripheral compartments allows calculation of the endogenous production. That holds even if the models are unidentifiable. The correct equation and Steele's pool fraction approximation reduce to the same result for this experimental design. However, that does not justify the use of Steele's equation when there are deviations from the exact experimental design. When the specific activity in the central compartment is not constant, model-dependent correction terms to Steele's equation are needed.

Production of volatile fatty acids in the sheep caecum

1969 ◽  
Vol 20 (3) ◽  
pp. 491 ◽  
Author(s):  
GJ Faichney
Keyword(s):  
Fatty Acids ◽  
Steady State ◽  
Fatty Acid ◽  
Production Rate ◽  
Energy Intake ◽  
Isotope Dilution ◽  
Volatile Fatty Acids ◽  
Specific Activity ◽  
Total Production ◽  
Digestible Energy

Acetic, propionic, and butyric acids labelled with 14C were infused into the caecum of continuously fed sheep. The specific activity of the volatile fatty acids (VFA) in the caecum was determined at intervals during the infusion. The production rate was calculated by isotope dilution from the results of those experiments in which steady state conditions were obtained. Substantial interconversions occurred between the fatty acid fractions. The total production of VFA was about 440 mmoles/day, equivalent to 125 kcal/day or 5.3% of the animal's digestible energy intake.

scholarly journals Droplets in homogeneous shear turbulence

2019 ◽  
Vol 876 ◽  
pp. 962-984 ◽  
Author(s):  
Marco E. Rosti ◽  
Zhouyang Ge ◽  
Suhas S. Jain ◽  
Michael S. Dodd ◽  
Luca Brandt
Keyword(s):  
Steady State ◽  
Production Rate ◽  
Droplet Size ◽  
Weber Number ◽  
Single Phase ◽  
Isotropic Turbulence ◽  
Turbulent Shear ◽  
Phase Flow ◽  
Carrier Fluid ◽  
The Mean

We simulate the flow of two immiscible and incompressible fluids separated by an interface in a homogeneous turbulent shear flow at a shear Reynolds number equal to 15 200. The viscosity and density of the two fluids are equal, and various surface tensions and initial droplet diameters are considered in the present study. We show that the two-phase flow reaches a statistically stationary turbulent state sustained by a non-zero mean turbulent production rate due to the presence of the mean shear. Compared to single-phase flow, we find that the resulting steady-state conditions exhibit reduced Taylor-microscale Reynolds numbers owing to the presence of the dispersed phase, which acts as a sink of turbulent kinetic energy for the carrier fluid. At steady state, the mean power of surface tension is zero and the turbulent production rate is in balance with the turbulent dissipation rate, with their values being larger than in the reference single-phase case. The interface modifies the energy spectrum by introducing energy at small scales, with the difference from the single-phase case reducing as the Weber number increases. This is caused by both the number of droplets in the domain and the total surface area increasing monotonically with the Weber number. This reflects also in the droplet size distribution, which changes with the Weber number, with the peak of the distribution moving to smaller sizes as the Weber number increases. We show that the Hinze estimate for the maximum droplet size, obtained considering break-up in homogeneous isotropic turbulence, provides an excellent estimate notwithstanding the action of significant coalescence and the presence of a mean shear.

Diffusing capacity of the lung in pulmonary emphysema

1964 ◽  
Vol 19 (5) ◽  
pp. 981-989 ◽  
Author(s):  
Stephen M. Ayres ◽  
Meta E. Buehler ◽  
Ruth G. Armstrong
Keyword(s):  
Gas Chromatography ◽  
Carbon Monoxide ◽  
Steady State ◽  
Body Size ◽  
Normal Subjects ◽  
Mean Value ◽  
Diffusing Capacity ◽  
Common Cause ◽  
Abnormal Distribution ◽  
The Mean

Steady-state CO and O2 methods for measuring pulmonary diffusing capacity may be affected by abnormal distribution of inspired gas relative to perfusion. These methods frequently fail to separate abnormalities in diffusion from abnormalities in distribution in patients with obstructive emphysema. A rebreathing CO method has been developed which, in theory, is less sensitive to inequalities in distribution. The DlCO by this method in 41 normal subjects averaged 20.8 ± 8.6 ml/min mm Hg and was closely correlated with body size and lung volume. Only 3 of 25 patients with obstructive emphysema had a DlCO less than the 95% confidence level although the mean value for all of the patients (16.8 ml/min mm Hg) was significantly lower than that of the normal group. It is concluded that loss of diffusing surface is not a common cause of oxyhemoglobin desaturation in obstructive emphysema. diffusion; carbon monoxide; ventilation-to-perfusion; gas chromatography Submitted on December 27, 1963

Clinical Studies on Inflammation in Human Knee Joints: Xenon (133Xe) Clearances Correlated with Clinical Assessment in Various Arthritides and Studies on the Effect of Intra-Articularly Administered Hydrocortisone in Rheumatoid Arthritis

1970 ◽  
Vol 38 (1) ◽  
pp. 123-133 ◽  
Author(s):  
C. Dick ◽  
K. Whaley ◽  
R. A. St. Onge ◽  
W. W. Downie ◽  
J. A. Boyle ◽  
...  
Keyword(s):  
Knee Joint ◽  
Clinical Improvement ◽  
Normal Subjects ◽  
Mean Value ◽  
Knee Joints ◽  
Joint Effusion ◽  
Human Knee ◽  
Significant Clinical Improvement ◽  
Disappearance Curve ◽  
The Mean

1. The rate of disappearance of intra-articularly administered 133Xe from the knee joint was studied in normal subjects and in patients suffering from various arthritides. The disappearance curve was monoexponential and could be described by a biological half life . The half lives were shown to be reproducible, but could be reduced marginally by aspirating knee joint effusion when present. 2. It was demonstrated that the values depended, not upon the pathological diagnosis, but upon the degree of inflammatory involvement of the knee joint at the time of study. 3. The effect of intra-articularly administered hydrocortisone upon the value was investigated in twenty-five rheumatoid subjects. The mean value obtained before injection of hydrocortisone was significantly lower than the mean value obtained 24 hr later. Significant clinical improvement was also noted. The relationship between individual clinical improvement and the change in value was examined.

Measuring Rates of Appearance in Systems Which are not in Steady State

1973 ◽  
Vol 51 (2) ◽  
pp. 91-101 ◽  
Author(s):  
Kenneth H. Norwich
Keyword(s):  
Steady State ◽  
Specific Activity ◽  
General System ◽  
Chemical Substance ◽  
Physiological System ◽  
Mathematical Basis ◽  
Endogenous Production ◽  
General Method

A general method is advanced for measuring the rate of appearance (production) of a chemical substance in an intact physiological system when this rate is changing with respect to time. The method involves infusing an isotope of this substance at such a rate that specific activity remains constant in space and in time. The means of achieving this constancy are discussed, and the mathematical basis of the method is developed for a fairly general system. An. experiment is described in some detail to show how the rate of endogenous production of glucose in a dog may be calculated when this rate is changing quite rapidly.

Sex Differences in the Metabolism of Ethanol and Acetaldehyde in Normal Subjects

1984 ◽  
Vol 67 (4) ◽  
pp. 397-401 ◽  
Author(s):  
M. J. P. Arthur ◽  
A. Lee ◽  
R. Wright
Keyword(s):  
Sex Differences ◽  
Elimination Rate ◽  
Young Male ◽  
Normal Subjects ◽  
Apparent Volume ◽  
Volume Of Distribution ◽  
Mean Value ◽  
The Mean ◽  
Ethanol Elimination ◽  
Apparent Volume Of Distribution

1. Blood ethanol and acetaldehyde concentrations were compared in normal young male and female subjects after intravenous infusion of 0.5 g of ethanol/kg body weight. 2. After the infusion was completed, females had significantly higher mean concentrations of blood ethanol than males, but a significantly lower apparent volume of distribution (Vd) of ethanol (0.56 ± 0.06 l/kg vs 0.68 ± 0.17 l/kg, P<0.05). There were no differences in ethanol elimination rate (EER) (females 1.78 ± 0.3 mmol h−1 kg−1; males 1.87 ± 0.41 mmol h−1 kg−1). The mean value of the areas under the acetaldehyde/time curves (AUC) were significantly greater for males (88.5 ± 26.4 μmol/l. h) than for females (58.6 ± 31.5 μmol/l. h, P<0.05). 3. Since the ethanol elimination rate was similar in both sexes, the observed differences in AUC for acetaldehyde may reflect the sex differences in metabolism of this substrate by the liver.

Instant 99mTc-Labelled Glucoheptonate Kit for Kidney Imaging

1983 ◽  
Vol 22 (05) ◽  
pp. 246-250 ◽  
Author(s):  
M. Al-Hilli ◽  
H. M. A. Karim ◽  
M. H. S. Al-Hissoni ◽  
M. N. Jassim ◽  
N. H. Agha
Keyword(s):  
Sodium Hydroxide Solution ◽  
Normal Subjects ◽  
Organ Distribution ◽  
Stable Complex ◽  
Scintillation Camera ◽  
Ph Adjustment ◽  
The Mean ◽  
The Stability ◽  
Kidney Imaging ◽  
Mean Concentration

Gelchromatography column scanning has been used to study the fractions of reduced hydrolyzed 99mTc, 99mTc-pertechnetate and 99mTc-chelate in a 99mTc-glucoheptonate (GH) preparation. A stable high labelling yield of 99mTc-GH complex in the radiopharmaceutical has been obtained with a concentration of 40-50 mg of glucoheptonic acid-calcium salt and not less than 0.45 mg of SnCl2 2 H2O at an optimal pH between 6.5 and 7.0. The stability of the complex has been found significantly affected when sodium hydroxide solution was used for the pH adjustment. However, an alternative procedure for final pH adjustment of the preparation has been investigated providing a stable complex for the usual period of time prior to the injection. The organ distribution and the blood clearance data of 99mTc-GH in rabbits were relatively similar to those reported earlier. The mean concentration of the radiopharmaceutical in both kidneys has been studied in normal subjects for one hour with a scintillation camera and the results were satisfactory.

A COMPARISON OF TWO METHODS FOR MEASUREMENT OF ALDOSTERONE SECRETION RATE IN MAN

1966 ◽  
Vol 53 (2) ◽  
pp. 177-188 ◽  
Author(s):  
P. Lund-Johansen ◽  
T. Thorsen ◽  
K. F. Støa
Keyword(s):  
Urinary Excretion ◽  
Normal Subjects ◽  
Secretion Rate ◽  
Aldosterone Secretion ◽  
Simple Method ◽  
Mean Values ◽  
Pathological Conditions ◽  
Significant Difference ◽  
Derivative Method ◽  
The Mean

ABSTRACT A comparison has been made between (A), a relatively simple method for the measurement of aldosterone secretion rate, based on paper chromatography and direct densitometry of the aldosterone spot and (B) a more elaborate isotope derivative method. The mean secretion rate in 9 normal subjects was 112 ± 26 μg per 24 hours (method A) and 135 ± 35 μg per 24 hours (method B). The »secretion rate« in one adrenalectomized subject after the intravenous injection of 250 μg of aldosterone was 230 μg per 24 hours (method A) and 294 μg per 24 hours (method B). There was no significant difference in the mean values, and correlation between the two methods was good (r = 0.80). It is concluded that the densitometric method is suitable for clinical purposes as well as research, being more rapid and less expensive than the isotope derivative method. Method A also measures the urinary excretion of the aldosterone 3-oxo-conjugate, which is of interest in many pathological conditions. The densitometric method is obviously the less sensitive and a prerequisite for its use is an aldosterone secretion of 20—30 μg per 24 hours. Lower values are, however, rare in adults.

VARIATION OF CORTISOL METABOLISM AS A CONTRIBUTING FACTOR TO DISCREPANCIES IN THE MEASUREMENT OF CORTISOL PRODUCTION RATE

1972 ◽  
Vol 70 (1) ◽  
pp. 89-96 ◽  
Author(s):  
M. J. Levell
Keyword(s):  
Production Rate ◽  
Isotope Dilution ◽  
Normal Subjects ◽  
Contributory Factor ◽  
Morning Dose ◽  
Production Rates ◽  
Evening Dose ◽  
Cortisol Metabolism

ABSTRACT Five normal subjects were given [14C] cortisol in the morning and [3H] cortisol in the evening, in both cases by mouth. The excretion of radioactivity in tetrahydrocortisol (THF) and tetrahydrocortisone (THE) was measured by a modified form of reverse isotope dilution. In 2 subjects, the ratio of isotopic THF/isotopic THE was higher after the evening dose than after the morning dose. In 1 subject the ratio decreased. In 2 subjects it did not change. Cortisol production rates calculated from THF were usually higher than those calculated from THE. The observed variations of metabolism were only a contributory factor to these discrepancies.

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