Nature of the Inhibition by Thiocyanate of the Iodide Concentrating Mechanism of the Thyroid Gland

1956 ◽  
Vol 186 (3) ◽  
pp. 453-459 ◽  
Author(s):  
Seymour H. Wollman
Keyword(s):  
Thyroid Gland ◽  
Active Transport ◽  
Experimental Error ◽  
Empirical Equation ◽  
Transport Models ◽  
Iodide Concentration ◽  
Serum Thiocyanate ◽  
Concentrating Mechanism

The dependence of the ratio of the radioiodide concentrations in thyroid gland and serum ( T/S) on the serum iodide concentration for fixed serum thiocyanate concentrations was investigated in C3H mice. The empirical equation (See PDF for Equation) where [SCN–] and [I–] are the serum thiocyanate and iodide concentrations in mg %, fitted the data within the limits of experimental error. Interpretation of the empirical equation was based on simple adsorption and active transport models of the iodide concentrating mechanism. The inhibition by thiocyanate of the thyroidal iodide concentrating mechanism appears to be competitive.

Acute Effect of Organic Binding of Iodine on the Iodide Concentrating Mechanism of the Thyroid Gland

1958 ◽  
Vol 194 (1) ◽  
pp. 28-32 ◽  
Author(s):  
Seymour H. Wollman ◽  
Franklin E. Reed
Keyword(s):  
Thyroid Gland ◽  
Intravenous Injection ◽  
Acute Effect ◽  
Total Iodine ◽  
Iodide Concentration ◽  
Concentrating Mechanism ◽  
Thyroid Glands

The organic binding of radioiodine by the thyroid gland of the mouse was blocked within 1 minute by the intravenous injection of 1 mg of propylthiouracil (PTU). In mice fed a very low iodine diet the ratio of the radioiodide concentration in the thyroid gland to that in the serum (T/S) was reduced significantly by injection of 1.5 µg of iodide 15 minutes before intravenous PTU injection. The amount of iodine bound prior to PTU injection was only a small percentage of the total iodine in the thyroid gland. This reduction did not occur in mice with less active thyroid glands. However, in the latter mice, doses of 22.5 µg of iodide or more injected 90 minutes before PTU caused a small but systematic decrease in the T/S when compared at fixed serum iodide concentration with mice given PTU before the iodide. In addition, in these mice given both PTU and iodide the T/S was greater than in mice given iodide but no PTU. It is concluded that the organic binding of iodine causes a decrease in the T/S in mice with active thyroid glands. In addition, PTU increases the T/S in mice in which organic binding of iodine is blocked by iodide.

Inhibition by thiocyanate of accumulation of radioiodine by thyroid gland

1962 ◽  
Vol 203 (3) ◽  
pp. 517-524 ◽  
Author(s):  
Seymour H. Wollman
Keyword(s):  
Thyroid Gland ◽  
Direct Effect ◽  
Appreciable Effect ◽  
Serum Thiocyanate ◽  
Concentrating Mechanism ◽  
Lack Of Information ◽  
Unambiguous Interpretation

An investigation was made to determine whether the inhibition by thiocyanate of the thyroidal accumulation of radioiodine can be accounted for by the well-known inhibition of the iodide concentrating mechanism, or whether, in addition, there is a direct effect on the iodination process. At the lower concentrations of serum thiocyanate the decrease in the thyroidal accumulation of radioiodine was proportional to the ratio of the thyroid and serum radioiodide concentrations (T/S) and no appreciable effect on the rate of incorporation of radioiodide per unit of thyroidal radioiodide into protein-bound I131 (PBI131) was observed. At higher serum thiocyanate concentrations the fraction of the thyroid radioiodide incorporated into PBI131 per minute decreased as the uptake decreased whereas the T/S was relatively constant. However, at this higher range of concentrations no unambiguous interpretation of the effect of thiocyanate could be made because of the lack of information about the distribution of radioiodide in the internal compartments of the thyroid. A comparison was made also of the effect of thiocyanate on the T/S when the iodination process was permitted with the effect on the T/S when iodination was blocked.

Computerized Computation of Emission Spectrometric Data of Trace Elements in Biological Fluids

1968 ◽  
Vol 22 (5) ◽  
pp. 552-557 ◽  
Author(s):  
Richard S. Johnson ◽  
William Niedermeier ◽  
James H. Griggs ◽  
Janice F. Lewis
Keyword(s):  
Trace Elements ◽  
Experimental Error ◽  
Functional Relationship ◽  
Empirical Equation ◽  
Biological Fluids ◽  
Transcendental Equation ◽  
Direct Reading ◽  
Spectrometric Data ◽  
Entire Procedure

It has been found that a four-constant generalized transcendental equation can be used to relate emission spectroscopy data to concentration of trace elements in biological fluids. For each element the constants in the- empirical equation are evaluated by a three-step successive approximation, based on the data from standards. The functional relationship, which gives values well within the range of experimental error, is then used in the quantitative determination of the concentration of each of 17 trace elements in unknown samples. In these studies a Jarrell—Ash direct reading spectrometer was used. The entire procedure of data reduction and concentration printout was done on a digital computer.

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 THE RELATION OF THE THYROID GLAND TO THE SURFACE TENSION OF THE BLOOD PLASMA

1926 ◽  
Vol 43 (2) ◽  
pp. 195-205 ◽  
Author(s):  
C. M. Wilhelmj ◽  
Moyer S. Fleisher
Keyword(s):  
Surface Tension ◽  
Thyroid Gland ◽  
Blood Plasma ◽  
Experimental Error ◽  
Thyroid Extract ◽  
Experimental Animals ◽  
Active Constituents ◽  
Normal Limits ◽  
Before And After ◽  
Surface Active

1. Determinations of the surface tension of blood plasma from guinea pigs, before and after feeding thyroxin, showed in most cases a definite decrease. Out of twenty-seven experimental animals, twenty showed a depression in the surface tension which ranged from 1.9 to 13.9 dynes, with an average of 5 dynes. Six animals showed variations hardly exceeding the limits of experimental error, while one showed an elevation of 1.1 dynes. 2. Six normal control animals, bled on the same days and kept under identical conditions, showed differences in the two determinations which ranged from a decrease of 0.5 to an increase of 0.6 of a dyne. One other control showed a drop of 1 dyne. 3. Two animals which had been fed large quantities of thyroid extract over a period of 10 days, gave values considerably below normal. One of these animals survived, and after 11 days during which no thyroid extract was given, the surface tension was found again to be within normal limits. 4. The hypothesis is advanced that these changes are due to an increase in the amount of certain normally occurring surface-active constituents, which are produced as a result of increased cellular metabolism.

scholarly journals Localized auxin peaks in concentration-based transport models of the shoot apical meristem

2015 ◽  
Vol 12 (106) ◽  
pp. 20141407 ◽  
Author(s):  
Delphine Draelants ◽  
Daniele Avitabile ◽  
Wim Vanroose
Keyword(s):  
Active Transport ◽  
Initial Conditions ◽  
Turing Instability ◽  
Variable Number ◽  
Transport Parameter ◽  
Transport Models ◽  
Auxin Production ◽  
Generic Class ◽  
Numerical Bifurcation ◽  
Parameter Values

We study the formation of auxin peaks in a generic class of concentration-based auxin transport models, posed on static plant tissues. Using standard asymptotic analysis, we prove that, on bounded domains, auxin peaks are not formed via a Turing instability in the active transport parameter, but via simple corrections to the homogeneous steady state. When the active transport is small, the geometry of the tissue encodes the peaks’ amplitude and location: peaks arise where cells have fewer neighbours, that is, at the boundary of the domain. We test our theory and perform numerical bifurcation analysis on two models that are known to generate auxin patterns for biologically plausible parameter values. In the same parameter regimes, we find that realistic tissues are capable of generating a multitude of stationary patterns, with a variable number of auxin peaks, that can be selected by different initial conditions or by quasi-static changes in the active transport parameter. The competition between active transport and production rate determines whether peaks remain localized or cover the entire domain. In particular, changes in the auxin production that are fast with respect to the cellular life cycle affect the auxin peak distribution, switching from localized spots to fully patterned states. We relate the occurrence of localized patterns to a snaking bifurcation structure, which is known to arise in a wide variety of nonlinear media, but has not yet been reported in plant models.

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