Free thyroxin and free triiodothyronine as measured by equilibrium dialysis and analog radioimmunoassay in serum of patients taking phenytoin and carbamazepine.

1985 ◽  
Vol 31 (12) ◽  
pp. 1993-1996 ◽  
Author(s):  
K Liewendahl ◽  
S Tikanoja ◽  
T Helenius ◽  
H Majuri
Keyword(s):  
Thyroid Hormones ◽  
Plasma Proteins ◽  
Equilibrium Dialysis ◽  
Immunoradiometric Assay ◽  
Free Triiodothyronine ◽  
Free Thyroid Hormones ◽  
Incremental Effect ◽  
The Mean ◽  
Mean Concentration

Abstract We measured free thyroxin (FT4) and free triiodothyronine (FT3) in serum of patients taking the anti-epileptic drugs phenytoin and carbamazepine, both by equilibrium dialysis procedures and analog-type radioimmunoassays. By either assay, the mean concentration of FT4 was significantly decreased in patients receiving either drug, whereas their FT3 concentrations were normal or only slightly decreased. Adding therapeutic concentrations of these drugs in vitro to control sera had a small or no incremental effect on FT4 and FT3 as measured by either method, but adding greater concentrations of the drugs in vitro markedly increased the concentrations of the free hormones. These results indicate that the main mechanism of the decrease in concentrations of free thyroid hormones in serum during therapy with anticonvulsant drugs is not the displacement of hormones from their binding to plasma proteins. We also determined, using a new and sensitive immunoradiometric assay, that patients taking carbamazepine, but not those taking phenytoin, had significantly less thyrotropin in the serum.

scholarly journals Theoretical consideration of the effects of dilution on estimates of free thyroid hormones in serum.

1984 ◽  
Vol 30 (5) ◽  
pp. 634-636 ◽  
Author(s):  
K Kamikubo ◽  
T Komaki ◽  
S Nakamura ◽  
S Sakata ◽  
K Yasuda ◽  
...  
Keyword(s):  
Thyroid Hormones ◽  
Serum Sample ◽  
Equilibrium Dialysis ◽  
Mathematical Formulation ◽  
Free Triiodothyronine ◽  
Free T4 ◽  
Free Thyroid Hormones ◽  
Multiple Binding Sites ◽  
Multiple Binding ◽  
Multiple Ligands

Abstract When concentrations of free thyroid hormones in serum are measured by equilibrium dialysis, the serum sample is diluted by dialysis buffer, resulting in a new equilibrium for distribution of these hormones that differs from that in the original serum sample. We have derived a mathematical formulation, based on an equilibrium model for multiple ligands and multiple binding sites, to determine the effect of dilution on the concentrations of free hormones in serum. Computer simulations based on the formulation indicate that both free thyroxin (T4) and free triiodothyronine (T3) are decreased by dilution of serum, free T3 being affected more than free T4. This dilution-related decrease is more prominent in hyperthyroidism than in euthyroidism, and even more striking for sera in which binding capacities for thyroid hormones are decreased (e.g., in thyroxin-binding globulin deficiency or hypoalbuminemia). These simulations can provide a basis for minimizing experimental errors in the estimates of concentrations of free thyroid hormones by equilibrium dialysis.

THE BINDING OF CORTISOL BY OVINE PLASMA PROTEINS

1967 ◽  
Vol 37 (3) ◽  
pp. 261-268 ◽  
Author(s):  
J. Y. F. PATERSON ◽  
F. HILLS
Keyword(s):  
Human Plasma ◽  
Plasma Proteins ◽  
Binding Capacity ◽  
Equilibrium Dialysis ◽  
Affinity Constant ◽  
Albumin Solution ◽  
Plasma Albumin ◽  
The Mean ◽  
Mean Concentration

SUMMARY Albumin was isolated from ovine plasma and its affinity for cortisol was determined by equilibrium dialysis at 37°. The value of Ka[σpa] for a 1 % (w/v) albumin solution was 0·275 which is similar to the value for human plasma albumin. The affinity constant of transcortin in ovine plasma was determined by equilibrium dialysis of diluted plasma at several concentrations of cortisol. The value found, Kt (37°) = 0·87 x 108 l./mole, is close to that found for human plasma transcortin by Mills (1962). The concentration of transcortin in ovine plasma, expressed as cortisolbinding capacity, was 6–49 μg. (mean 24 μg.) cortisol/l. These concentrations are much lower than those found in human plasma. The observation of Lindner (1964) that cortisol binding capacity did not increase during pregnancy in sheep has been confirmed. In sheep which were accustomed to handling, the mean concentration of cortisol in plasma was 17·8 μg./l. and of this amount 59% was bound to transcortin, 19 % to albumin and 22 % was not bound to protein.

scholarly journals Sensitivity of Rhizoctonia solani AG-2-2 from Sugar Beet to Fungicides

Plant Disease ◽  
2016 ◽  
Vol 100 (12) ◽  
pp. 2427-2433 ◽  
Author(s):  
Sahar Arabiat ◽  
Mohamed F. R. Khan
Keyword(s):  
Sugar Beet ◽  
Rhizoctonia Solani ◽  
Root Rot ◽  
The United States ◽  
Damping Off ◽  
Growth Assay ◽  
The Mean ◽  
Crown And Root Rot ◽  
Mean Concentration

Rhizoctonia damping-off and crown and root rot caused by Rhizoctonia solani are major diseases of sugar beet (Beta vulgaris L.) worldwide, and growers in the United States rely on fungicides for disease management. Sensitivity of R. solani to fungicides was evaluated in vitro using a mycelial radial growth assay and by evaluating disease severity on R. solani AG 2-2 inoculated plants treated with fungicides in the greenhouse. The mean concentration that caused 50% mycelial growth inhibition (EC50) values for baseline isolates (collected before the fungicides were registered for sugar beet) were 49.7, 97.1, 0.3, 0.2, and 0.9 μg ml−1 and for nonbaseline isolates (collected after registration and use of fungicides) were 296.1, 341.7, 0.9, 0.2, and 0.6 μg ml−1 for azoxystrobin, trifloxystrobin, pyraclostrobin, penthiopyrad, and prothioconazole, respectively. The mean EC50 values of azoxystrobin, trifloxystrobin, and pyraclostrobin significantly increased in the nonbaseline isolates compared with baseline isolates, with a resistant factor of 6.0, 3.5, and 3.0, respectively. Frequency of isolates with EC50 values >10 μg ml−1 for azoxystrobin and trifloxystrobin increased from 25% in baseline isolates to 80% in nonbaseline isolates. Although sensitivity of nonbaseline isolates of R. solani to quinone outside inhibitors decreased, these fungicides at labeled rates were still effective at controlling the pathogen under greenhouse conditions.

Binding of 63Ni(II) to Ultrafiltrable Constituents of Rabbit Serum In Vivo and In Vitro

1975 ◽  
Vol 21 (4) ◽  
pp. 521-527 ◽  
Author(s):  
Noritake Asato ◽  
Maria van Soestbergen ◽  
F William Sunderman
Keyword(s):  
Rabbit Serum ◽  
Total Serum ◽  
In Vivo Experiments ◽  
The Mean ◽  
Layer Chromatography ◽  
In Vivo Administration ◽  
Mean Concentration

Abstract Binding of 63Ni(Il) to ultrafiltrable constituents of rabbit serum was studied (a) after in vitro incubation (2 h, 37 °C) of rabbit serum with 63NiCl2 (10-100 µmol/liter), and (b) at intervals (0.25-2 h) after in vivo administration of 63NiCl2 (40-160 µmol/kg body wt, i.v.). Serum ultrafiltrates were fractionated by thin-layer chromatography, and the separated compounds made visible by autoradiography and by ninhydrin staining. Several (≃5) ultrafiltrable 63Ni-complexes were demonstrable as distinct radiodense 63Ni-bands with chromatographic mobilities corresponding to those of ninhydrin-positive bands. Unbound 63Ni(II) was not detected in serum ultrafiltrates in either the in vitro or in vivo experiments. In sera (n = 10) incubated in vitro with 63Ni(II) (10 µmol/ liter), the mean percentage of ultrafiltrable 63Ni was 36% (range = 33-38) of total serum 63Ni. In contrast, in sera (n = 10) obtained 2 h after i.v. injection of 63Ni(II) (40 µmol/kg), the mean concentration of total serum 63Ni was 10.8 µmol/liter (range = 6-14), and the mean percentage of ultrafiltrable 63Ni was 15% (range = 9-21) of total serum 63Ni. The disparity between the percentages of ultrafiltrable 63Ni obtained in vitro and in vivo was obviated when the in vivo experiments were performed in rabbits bilaterally nephrectomized, with ligated common bile ducts. This investigation confirms the existence of several nickel receptors in serum ultrafiltrates and substantiates the role of ultrafiltrable complexes in the excretion of nickel.

Associations of Thyroid Hormones and Resting Heart Rate in Patients Referred to Coronary Angiography

2020 ◽  
Vol 52 (12) ◽  
pp. 850-855
Author(s):  
Eva Steinberger ◽  
Stefan Pilz ◽  
Christian Trummer ◽  
Verena Theiler-Schwetz ◽  
Markus Reichhartinger ◽  
...  
Keyword(s):  
Heart Rate ◽  
Coronary Angiography ◽  
Thyroid Hormones ◽  
Thyroid Stimulating Hormone ◽  
Resting Heart Rate ◽  
Free Triiodothyronine ◽  
Free Thyroid Hormones ◽  
Cardiovascular Morbidity And Mortality ◽  
Increased Risk ◽  
Significant Difference

AbstractResting heart rate (RHR) is associated with increased risk of cardiovascular morbidity and mortality. Thyroid hormones exert several effects on the cardiovascular system, but the relation between thyroid function and RHR remains to be further established. We evaluated whether measures of thyroid hormone status are associated with RHR in patients referred to coronary angiography. Thyroid-stimulating hormone (TSH), free triiodothyronine (FT3), free thyroxin (FT4), and RHR were determined in 2795 participants of the Ludwigshafen Risk and Cardiovascular Health (LURIC) Study. Median (25th to 75th percentile) serum concentrations were 1.25 (0.76–1.92) mU/l for TSH, 4.8 (4.2–5.3) pmol/l for FT3 and 17.1 (15.4-19.0) pmol/l for FT4, and mean (±standard deviation) RHR was 68.8 (±11.7) beats/min. Comparing the highest versus the lowest quartile, RHR (beats/min) was significantly higher in the fourth FT4 quartile [3.48, 95% confidence interval (CI): 2.23–4.73; p <0.001] and in the fourth FT3 quartile (2.30, 95% CI: 1.06–3.55; p <0.001), but there was no significant difference for TSH quartiles. In multiple linear regression analyses adjusting for various potential confounders, FT3 and FT4 were significant predictors of RHR (p <0.001 for both). In subgroups restricted to TSH, FT3, and FT4 values within the reference range, both FT3 and FT4 remained significant predictors of RHR (p <0.001 for all). In conclusion, in patients referred to coronary angiography, FT3 and FT4 but not TSH were positively associated with RHR. The relationship between free thyroid hormones and RHR warrants further investigations regarding its diagnostic and therapeutic implications.

scholarly journals The Discrimination between Magnesium and Manganese by Serum Proteins

1967 ◽  
Vol 50 (9) ◽  
pp. 2255-2266 ◽  
Author(s):  
A. C. Foradori ◽  
Albert Bertinchamps ◽  
Jane M. Gulibon ◽  
George C. Cotzias
Keyword(s):  
Transition Metal ◽  
Trace Metal ◽  
Plasma Proteins ◽  
Alkaline Earth ◽  
Serum Proteins ◽  
Equilibrium Dialysis ◽  
Zone Electrophoresis ◽  
Biological Specificity ◽  
Isolated Systems

Magnesium and manganese have proved physically and functionally interchangeable in many isolated biological systems investigated in vitro. This lack of discrimination contrasts sharply with the high biological specificity exhibited by intact mammals under a large variety of conditions. The dichotomy between intact animals and their isolated systems might be due at least partially to presence vs. absence of an intact circulation. Hence the capability of mammalian plasma to discriminate between the alkaline earth and the transition metal was investigated by means of equilibrium dialysis, exchange, ultrafiltration, ultracentrifugation, and zone electrophoresis. The states of the respective elements are thus contrasted as follows: (a) Magnesium is partially bound, manganese totally. (b) Magnesium is nonselectively bound by serum proteins, manganese selectively by a ß1-globulin. (c) Under conditions approaching physiological, the two metals do not interchange. This is interpreted as indicating that the plasma proteins contribute to biological specificity by discriminating between a trace metal and a macronutrient.

scholarly journals Some Physiological Factors Affecting the Binding of Cortisol by Human Plasma Proteins

1977 ◽  
Vol 14 (1-6) ◽  
pp. 35-38 ◽  
Author(s):  
J. D. Few ◽  
J. R. Haspineall
Keyword(s):  
Steady State ◽  
Human Plasma ◽  
Plasma Proteins ◽  
Gel Filtration ◽  
Physiological Factors ◽  
Mean Values ◽  
Factors Affecting ◽  
Free Cortisol ◽  
The Mean

Steady-state gel filtration has been used to study the binding of cortisol to human plasma proteins in vitro. Raising the temperature from 37°C to 41°C results in the mean proportion of free (non-protein-bound) cortisol rising approximately from 7% to 11%. Addition of cortisol to plasma ≡ 275 nmol/l) also increased the proportion of free cortisol by approximately 50%. Cortisone is less strongly bound to plasma proteins than cortisol. The mean values (±S.D.) for five samples were free cortisol 8.4 ± 1.1% and free cortisone 26.0±3.8%.

Discrepancies between serum free triiodothyronine and free thyroxin as measured by equilibrium dialysis and analog radioimmunoassay in nonthyroidal illnesses.

1984 ◽  
Vol 30 (5) ◽  
pp. 760-762 ◽  
Author(s):  
K Liewendahl ◽  
S Tikanoja ◽  
T Helenius ◽  
M Välimäki
Keyword(s):  
Serum Albumin ◽  
Equilibrium Dialysis ◽  
Healthy Controls ◽  
Free Triiodothyronine ◽  
Serum Free ◽  
The Mean

Abstract We determined free triiodothyronine (FT3) and free thyroxin (FT4) in serum of patients with various nonthyroidal illnesses (NTI), by both commercial analog-type radioimmunoassays (A) and new equilibrium dialysis procedures (D). The mean FT3 was significantly lower in NTI by both techniques, but the decreases were of different magnitudes. The FT3(D):FT3(A) ratio was 1.96, vs 1.11 for healthy controls. In NTI the mean FT4(D) was somewhat increased, whereas the mean FT4(A) was much lower than normal, the above ratio being 1.70, vs 0.92 for controls. We ascribe these discrepancies, at least in part, to binding of radiolabeled T3- and T4-analog tracers to serum albumin.

scholarly journals Correlations of Free Thyroid Hormones Measured by Tandem Mass Spectrometry and Immunoassay with Thyroid-Stimulating Hormone across 4 Patient Populations

2009 ◽  
Vol 55 (7) ◽  
pp. 1380-1388 ◽  
Author(s):  
Jacqueline Jonklaas ◽  
Natasa Kahric-Janicic ◽  
Offie P Soldin ◽  
Steven J Soldin
Keyword(s):  
Mass Spectrometry ◽  
Thyroid Hormone ◽  
Tandem Mass Spectrometry ◽  
Thyroid Hormones ◽  
Thyroid Stimulating Hormone ◽  
Free Thyroxine ◽  
Tandem Mass ◽  
Free Triiodothyronine ◽  
Free Thyroid Hormones ◽  
Free Thyroid Hormone

Abstract Background: Accurate measurement of free thyroid hormones is important for managing thyroid disorders. Ultrafiltration liquid chromatography tandem mass spectrometry (LC-MS/MS) can reliably measure the concentrations of small molecules, including thyroid hormones. Our study was designed to compare free thyroid hormone measurements performed with immunoassay and LC-MS/MS. Methods: We studied the performance of LC-MS/MS in 4 different populations comprising pediatric patients, euthyroid adults, and healthy nonpregnant and pregnant women. The samples obtained from each population numbered 38, 200, 28, and 128, respectively. Free thyroxine, free triiodothyronine, and thyroid-stimulating hormone (TSH) concentrations were documented. Results: LC-MS/MS measurement of free thyroid hormones provided better correlation with log-transformed serum TSH in each population and also the populations combined. The correlations between free thyroxine measured by LC-MS/MS and log TSH in the pediatric outpatients and healthy adults were −0.90 and −0.77, respectively. The correlations for immunoassay were −0.82 and −0.48. The correlations between free triiodothyronine measured by LC-MS/MS and TSH for both pediatric and healthy adult populations were −0.72 and −0.68, respectively. Conclusions: Free thyroid hormone concentrations measured by LC-MS/MS correlate to a greater degree with log TSH values compared to concentrations measured by immunoassay. This correlation was maintained across the patient populations we studied and may reflect the accuracy and specificity of LC-MS/MS. The superior ability of LC-MS/MS to enable documentation of the well-known thyroid hormone–TSH relationship supports the use of this measurement technique in a variety of clinical situations.

Bicarbonate transport by isolated perfused rabbit proximal convoluted tubules

1977 ◽  
Vol 233 (4) ◽  
pp. F307-F314 ◽  
Author(s):  
M. Burg ◽  
N. Green
Keyword(s):  
Hydrogen Ion ◽  
Bicarbonate Transport ◽  
Fluid Absorption ◽  
The Mean ◽  
Tubule Cells ◽  
The Relationship ◽  
Convoluted Tubules ◽  
Mean Concentration ◽  
Proximal Convoluted Tubules

Proximal convoluted tubules were dissected from rabbit kidneys and perfused in vitro in order to investigate the relationship between the reabsorption of fluid and of bicarbonate. Bicarbonate was absorbed when it was initially present in the perfusate. At slow rates of perfusion the mean concentration of total CO2 was 9 mM in collected fluid with 25 mM bicarbonate in the bath. At faster rates of perfusion the mean rate of reabsorption was 13.6 pmol cm-1 tubule length s-1. Absorption of bicarbonate was inhibited to a large but not complete extent by elimination of sodium from the perfusate and bath or potassium from the bath, and by addition of ouabain. It was not inhibited by elimination of the organic solutes from the perfusate nor by elimination of chloride from the perfusate and bath. Considered with previous measurements of fluid absorption these results are consistent with the existence of a linked sodium-for-hydrogen ion exchange mechanism at the luminal border of the tubule cells, but there are other possibilities which are discussed. Additionally, the effect of acetazolamide was investigated. The drug virtually completely inhibited bicarbonate absorption and inhibited fluid absorption by 30-40%.

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