Transport of radioiodide between thyroid gland and blood in mice and rats

1958 ◽  
Vol 196 (1) ◽  
pp. 113-120 ◽  
Author(s):  
Seymour H. Wollman ◽  
Franklin E. Reed
Keyword(s):  
Single Dose ◽  
Thyroid Gland ◽  
Rate Constant ◽  
Experimental Error ◽  
Compartment Model ◽  
Exit Rate ◽  
Follicular Cells ◽  
Thyroid Activity ◽  
Two Compartment Model ◽  
Rats And Mice

Equilibration data were obtained for thyroids of various activities in rats and mice given a single dose of propylthiouracil to block organic binding of radioiodine. Data were compared with an open two-compartment model of the thyroid characterized by a one-way thyroid clearance of serum radioiodide and an exit rate constant for the transport of radioiodide from the thyroid to the blood. The model generally fitted the data within experimental error. Clearances increased with thyroid activity. Exit rate constants were much larger for animals fed thiouracil than for other animals. Thiocyanate increased the exit rate constant but did not change the thyroid clearance of serum radioiodide significantly. A new open three-compartment thyroid model was introduced and was used to explain how thiocyanate could increase the exit rate constant by inhibiting the transport of iodide from the follicular cells to the lumen of the follicle.

scholarly journals 1573. Population Pharmacokinetic Analyses for Cefepime in Adult and Pediatric Patients

2019 ◽  
Vol 6 (Supplement_2) ◽  
pp. S574-S575
Author(s):  
Jiajun Liu ◽  
Michael Neely ◽  
Jeffrey Lipman ◽  
Fekade B Sime ◽  
Jason Roberts ◽  
...  
Keyword(s):  
Rate Constant ◽  
Pediatric Patients ◽  
Validation Cohort ◽  
External Validation ◽  
Compartment Model ◽  
Volume Of Distribution ◽  
Information Criteria ◽  
Population Pharmacokinetic ◽  
Final Model ◽  
Two Compartment Model

Abstract Background Cefepime (CEF) is commonly used for adult and pediatric infections. Several studies have examined CEF’s pharmacokinetics (PK) in various populations; however, a unifying PK model for adult and pediatric subjects does not yet exist. We developed a combined population model for adult and pediatric patients and validated the model. Methods The initial model includes adult and pediatric patients with a rich cefepime sampling design. All adults received 2 g CEF while pediatric subjects received a mean of 49 (SD 5) mg/kg. One- and two-compartment models were considered as base models and were fit using a non-parametric adaptive grid algorithm within the Pmetrics package 1.5.2 (Los Angeles, CA) for R 3.5.1. Compartmental model selection was based on Akaike information criteria (AIC). Covariate relationships with PK parameters were visually inspected and mathematically assessed. Predictive performance was evaluated using bias and imprecision of the population and individual prediction models. External validation was conducted using a separate adult cohort. Results A total of 45 subjects (n = 9 adults; n = 36 pediatrics) were included in the initial PK model build and 12 subjects in the external validation cohort. Overall, the data were best described using a two-compartment model with volume of distribution (V) normalized to total body weight (TBW/70 kg) and an allometric scaled elimination rate constant (Ke) for pediatric subjects (AIC = 4,138.36). Final model observed vs. predicted plots demonstrated good fit (population R2 = 0.87, individual R2 = 0.97, Figure 1a and b). For the final model, the population median parameter values (95% credibility interval) were V0 (total volume of distribution), 11.7 L (10.2–14.6); Ke for adult, 0.66 hour−1 (0.38–0.78), Ke for pediatrics, 0.82 hour−1 (0.64–0.85), KCP (rate constant from central to peripheral compartment), 1.4 hour−1 (1.3–1.8), KPC (rate constant from peripheral to central compartment), 1.6 hour−1 (1.2–1.8). The validation cohort has 12 subjects, and the final model fit the data well (individual R2 = 0.75). Conclusion In this diverse group of adult and pediatrics, a two-compartment model described CEF PK well and was externally validated with a unique cohort. This model can serve as a population prior for real-time PK software algorithms. Disclosures All authors: No reported disclosures.

AN EXPERIMENTAL ANALYSIS OF THE EFFECTS OF OESTROGEN ON THE THYROID GLAND OF CASTRATED ADULT MALE RATS

1968 ◽  
Vol 40 (4) ◽  
pp. 397-408 ◽  
Author(s):  
J. F. BITHELL ◽  
K. BROWN-GRANT
Keyword(s):  
Thyroid Gland ◽  
Rate Constant ◽  
Adult Male ◽  
Time Course ◽  
Hormone Secretion ◽  
Male Rats ◽  
Male Rat ◽  
Exit Rate ◽  
Experimental Conditions

SUMMARY The uptake of 131I by the thyroid gland of the castrated adult male rat is increased 24 hr. and is maximal 48 hr. after the injection of a single dose of 50 μg. oestradiol. The response is not dose-dependent between 25 and 1600 μg. The thyroid:serum (T:S) concentration ratio for 131I is also increased by oestradiol with a time-course similar to the changes in uptake, but release of 131I-labelled hormone from the gland in vivo and radioactive phosphate uptake were not affected. Analysis of the kinetics of 131I accumulation by the blocked gland show that the effects on 131I uptake and T:S ratio were due to an increase in the clearance rate with a possible associated decrease in the exit rate constant for iodide from the gland to the blood. Under the conditions of these experiments, the effects of oestradiol are not consistent with their being produced by an increase in pituitary thyrotrophic hormone secretion; a direct action on the gland appears likely. These conclusions apply solely to the experimental conditions described here and do not provide the basis for any generalization about the action of oestrogens on the thyroid gland. The method of analysis developed for the estimation of the unilateral clearance constant and the exit rate constant, together with their standard deviations, is presented in an appendix.

ADRENAL FUNCTION IN BREAST CANCER: THE DISTRIBUTION OF CORTISOL IN PATIENTS WITH EARLY OR ADVANCED BREAST CANCER AND IN NORMAL WOMEN

1968 ◽  
Vol 42 (3) ◽  
pp. 433-439 ◽  
Author(s):  
V. JENSEN ◽  
N. DESHPANDE ◽  
R. D. BULBROOK ◽  
T. W. DOOUSS
Keyword(s):  
Breast Cancer ◽  
Advanced Breast Cancer ◽  
Compartment Model ◽  
Advanced Breast ◽  
Exit Rate ◽  
Breast Cancer Patients ◽  
Transfer Processes ◽  
Two Compartment Model ◽  
Extrahepatic Metabolism ◽  
Normal Women

SUMMARY The distribution of cortisol in patients with early or advanced breast cancer and in controls was studied, using a two-compartment model for analysis. The patients with advanced breast cancer had significantly raised pool sizes. There were no significant differences in the ratio of two pools found for patients and controls. This suggests that there are no abnormalities in the transfer processes. There was a significant correlation between the exit rate from the intravascular pool and the production rate of cortisol, showing that there is no major extrahepatic metabolism of this hormone in both controls and in breast-cancer patients.

Efflux du 36Cl et distribution du Cl dans le muscle papillaire du lapin, effet de l'ouabaïne

1981 ◽  
Vol 59 (8) ◽  
pp. 794-799
Author(s):  
Jean-Pierre Caillé
Keyword(s):  
Rate Constant ◽  
Papillary Muscle ◽  
Compartment Model ◽  
Rapid Rate ◽  
Extracellular Medium ◽  
Cellular Compartment ◽  
Rapid Exchange ◽  
Two Compartment Model ◽  
In Series

The 36Cl efflux "in vivo" was measured in the rabbit papillary muscle to determine the Cl distribution in the muscle and to evaluate the effect of ouabain on this parameter. The results obtained for the 36Cl efflux are analyzed using either a two-compartment model or a model including diffusion in the extracellular space in series with one compartment. The Cl exchange with 36Cl, *[Cl]i (intracellular Cl content which has participated in exchanges. [Formula: see text]) is computed from the exponential terms of the models. A time exposure of 40 and 80 min to the 36Cl-containing solution led to the same exchange Cl content: 20.5 and 23.9 mmol/kg cells. Addition of ouabain (10−6M) slightly increased the rate constant of the cellular compartment, but did not influence the *[Cl]i. In the presence of ouabain (10−6M), there was a significant increase in the efflux component with a rapid rate constant. These results can be interpreted as follows: the Cl intracellular concentration is not affected by ouabain; thus, the increase in total Cl content induced in the papillary muscle by ouabain is located in a compartment having a very rapid exchange velocity with the extracellular medium.[Journal translation]

Thyroid function as measured by 131iodine release rate, weight and RNA/DNA in growing lambs, and its relation to growth rate

1969 ◽  
Vol 11 (3) ◽  
pp. 399-407 ◽  
Author(s):  
S. A. Draper ◽  
N. B. Haynes ◽  
I. R. Falconer ◽  
G. E. Lamming
Keyword(s):  
Growth Rate ◽  
Thyroid Hormone ◽  
Thyroid Gland ◽  
Thyroid Function ◽  
Rate Constant ◽  
Release Rate ◽  
Hormone Secretion ◽  
Thyroid Status ◽  
Thyroid Activity ◽  
Ad Libitum

SUMMARYThyroid activity was assessed in two groups of crossbred lambs and in Dorset Horn lambs fed ad libitum, by measuring the rate constant (K4) for the release of 131iodine from the gland. The results demonstrated a highly significant curvilinear correlation (P<0·001) between growth rate and the rate constant (K4) in experiments based on individual measurements in animals from three populations.Separate work carried out on the measurements of both thyroid size and RNA/DNA ratio suggests a need for caution when these are interpreted as parameters of thyroid activity. In the growing animal these may be more reflective of the growth of the thyroid gland itself, differences which may be governed by factors not directly related to variations in hormone secretion rate.The findings are discussed in terms of an explanation of the contradictory results obtained where attempts have been made to alter the thyroid status of growing animals by the use of thyroid hormone analogues and thyroid depressant drugs.

scholarly journals A Comparison Between The Pharmacokinetics Of Gentamicin And Its Mixture With Calcium In Rabbits

2004 ◽  
Vol 28 (1) ◽  
pp. 214-226
Author(s):  
Murouj Abdul-Sattar Al-Ubaydi ◽  
Duraid Abdulhadi Abbass
Keyword(s):  
Single Dose ◽  
Compartment Model ◽  
Free Drug ◽  
Lower Plasma ◽  
Toxic Side Effect ◽  
First Order ◽  
Two Compartment Model ◽  
Gentamicin Concentration ◽  
Mixture Group ◽  
Gentamicin Sulphate

Pharamcokinetic studies were performed for gentamicin sulphate at single dose of 5 mg/kg compared with formullae of same dose of gentamicin with calcium gluconate at a dose of 7.5 mg/kg injected i.v. and i.m. to four groups of 5 rabbits. The results of i.v. injection showed elimination of first order two compartment model with lower plasma gentamicin concentration, lower inhibition bacterial period and increase of gentamicin clearance in mixture group may be due to its competition with calcium for albumin which increase the free drug available for excretion and distribution while after i.m. injection absorption of gentamicin from formullae was lower but its plasma elimination (B) was slower with nearly same inhibition bacterial period as in gentamicin dosed group. These results explain kinetically why calcium lower gentamicin toxic side effect after i.m. and i.v. injection.

Accumulation of radioiodine in thiouracil-hyperplastic thyroids of chicks.

1979 ◽  
Vol 237 (2) ◽  
pp. E147
Author(s):  
W S Newcomer
Keyword(s):  
Thyroid Gland ◽  
Latent Period ◽  
Rate Constant ◽  
Normal Level ◽  
Control Level ◽  
Exit Rate ◽  
Kinetics Of

Kinetics of accumulation of radioiodine was studied in thyroids of chickens before, during, and following ingestion of 0.25% thiouracil (TU). After a latent period of about 5 days, weight of the thyroid gland increased, reaching its maximum (42 mg/100 g body wt) after 21 days of TU ingestion; thyroid weight decreased immediately on withdrawal of TU but tended to plateau at a higher level than that of controls. One-way clearance increased by day 4 of ingestion of TU and reached its peak early during hyperplasia; it very quickly reverted to a control level on withdrawal of TU. Exit-rate constant increased markedly during early hyperplasia and decreased to a level less than normal after withdrawal of TU. Concentration of 127I decreased by a factor of 18 by 2 wk of feeding TU; it increased to practically a normal level by 1 wk after withdrawal of TU.

A New Method for the Estimation of Absorption Rate Constant in Two-Compartment Model by Extravascular Administration

2020 ◽  
Vol 109 (5) ◽  
pp. 1802-1810 ◽  
Author(s):  
Ye Zeng ◽  
Jianxiong Liu ◽  
Wenjie Liu ◽  
Shan Jiang ◽  
Shanshan Wang ◽  
...  
Keyword(s):  
Rate Constant ◽  
Absorption Rate ◽  
Compartment Model ◽  
New Method ◽  
Absorption Rate Constant ◽  
Two Compartment Model

Dietary iodine and thyroidal iodide transport in chickens: organic binding blocked.

1978 ◽  
Vol 234 (2) ◽  
pp. E177
Author(s):  
W S Newcomer
Keyword(s):  
Experimental Data ◽  
Protein Binding ◽  
Rate Constant ◽  
Experimental Error ◽  
Compartmental Model ◽  
Single Injection ◽  
Iodine Content ◽  
Exit Rate ◽  
Iodide Transport

Experimental data concerning the increase in T/S [I-] (ratio of concentration of radioiodide in thyroid to that in serum) during equilibration after a single injection of radioidide were obtained from chickens in which protein binding of radioidide was inhibted by methimazole. Equilibration data were obtained from chickens fed a low-iodine diet (2 mo) as well as the low-iodine diet to which various amounts of NaI had been added. Experimental data were compared with productions based on the open two-compartmental model of Wollman and Reed (Am. J. Physiol. 196: 113-120, 1959). Thyroidal clearance (C/m) of radioiodide (the rate at which radioiodide is transferred from blood into the thyroid and equal to the radioiodide content of C microliter serum per minute) varied inversely to iodine content of feed. Exit rate constant (KTB, the fraction of thyroidal radioiodide transferred to serum per minute) was relatively more constant. The experimental data fitted the predictions from the model within experimental error. Thirty days of feeding the low-iodine diet was required before C/m stabilized at 50 microliter/min per mg and KTB at 0.065; stabilization of C/m and KTB occurred in 12 days with the highest iodine diet.

Sign in / Sign up

Export Citation Format

Share Document