The Thyroxine-Binding Properties of Serum Proteins. A Competitive Binding Technique Employing Sephadex G-25

Sutherland, Robert L.; Simpson‐Morgan, M. W.

doi:10.1677/joe.0.0650319

Cited by 28 publications

(21 citation statements)

References 18 publications

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“…The fact that there does not exist any significant difference in the distribution volumes or in the a-phase of distribution between the disease-induced sheep and the controls, indicates that there probably exists no important modification in the binding of the thyroxine to the plasma transport proteins. The transport of T 4 and T 3 in sheep is seen to be similar to that of man, Sutherland, Simpson-Morgan (1975) having demonstrated that plasma transport proteins in these animals are similar to human TBG and TBPA. Barzilai, Soloway, Summerskill and Schoenfield (1974) have indicated a reduction in the binding of T 4 to plasma proteins in patients with active chronic hepatopathies.…”

Section: Thyroxine A) Control Studiesmentioning

confidence: 78%

The Kinetics of the Thyroid Hormones and the Peripheral Conversion Rate of Thyroxine to Triiodothyronine in Acute Liver Insufficiency under Experimental Conditions

Jm¹,

García-Iglesias²,

Lc³

et al. 1981

Horm Metab Res

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The kinetics of triiodothyronine (T3) and thyroxine (T4) were studied in 20 ewes. Ten were used as the control group, the other 10 received massive hepatic lesions induced by the ingestion of carbon tetrachloride. Half of each group were i.v. injected with 125 IT3 or 125 IT4, following a plasma disappearance over 96 hours. The amount of hormone present in each plasma sample was determined by immunoextraction procedure. The data was adjusted to the open two-compartment modelThe hepatic insufficiency provoked a decrease in the disposition constant of T3, an increase in the plasma half-life of the distribution phase as well as a moderately decreased turnover rate of this hormone.The T4 kinetics were altered during acute hepatic insufficiency in the decrease of the elimination constant K13 and hormone plasma turnover rate.The study of the peripheral conversion rate based on the kinetic data showed an extrathyroidal conversion of T4 to T3 in the control sheep, none being detected in the sheep with induced hepatic insufficiency.

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Section: Thyroxine A) Control Studiesmentioning

confidence: 78%

The Kinetics of the Thyroid Hormones and the Peripheral Conversion Rate of Thyroxine to Triiodothyronine in Acute Liver Insufficiency under Experimental Conditions

Jm¹,

García-Iglesias²,

Lc³

et al. 1981

Horm Metab Res

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“…Other methods for the measurement of TBG combine immunological and thyroid hormone-binding techniques, such as those described by Chopra et al (22) and used in the Corning Immophase TBG kit (23). Although STBG was detected in sera of patients with hepatic cirrhosis (2) and more recently was found to be a constituent of normal serum (24), measurements of TBG capacity at saturation have been, in general, consistent with values obtained using immunological techniques (1,6,8,11,13,14,16,17,21). This is not surprising, since native TBG and STBG have identical antigenic determinants, and both have a single binding site for T 4 (2)(3)(4).…”

mentioning

confidence: 70%

“…JCE&M«1984 Vol 59 • No 2 measurement of TBG concentration by immunological techniques. Methods for the estimation of the binding capacity are based on the proportion of isotopically labeled T 4 bound to TBG at a known concentration of total T 4 (8)(9)(10)(11)(12)(13)(14). Immunological techniques for the measurement of TBG include RIAs (15)(16)(17), enzyme immunoassays (18), rocket immunoelectrophoresis (19,20), and radial immunodiffusion (21).…”

mentioning

confidence: 99%

Radioimmunoassays Specific for the Tertiary and Primary Structures of Thyroxine-Binding Globulin (TBG): Measurement of Denatured TBG in Serum*

Refetoff

Murata

Vassart

et al. 1984

The Journal of Clinical Endocrinology & Metabolism

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Antisera prepared by immunization of rabbits with human T4-binding globulin (TBG) contained two populations of antibodies: one directed against determinants of the native molecule, and the other directed against antigenic sites present only in denatured TBG. These two populations of antibodies were present in all nine antisera prepared in this or other laboratories that were tested. Exploiting this property of anti-TBG sera and using radioiodinated denatured TBG as a tracer, a RIA was developed which measures specifically denatured TBG in the presence of native TBG. The RIA for measuring denatured TBG used purified native TBG, which was denatured by reduction and pyridylethylation (RP-TBG) before labeling with 125I. Native TBG was measured using the same antiserum, but the 125I-labeled tracer was unmodified TBG. The sensitivity of the native TBG RIA was 0.25 ng purified native TBG. Equivalent amounts of native TBG in serum, desialylated TBG, and deglycosylated TBG produced superimposeable standard curves. The cross-reactivity with RP-TBG was less than 0.02%. The denatured TBG RIA had a sensitivity of 1 ng, and superimposeable curves were produced with equivalent concentrations of RP-TBG and heat-denatured native TBG. The cross-reactivity of 0.8% with native and deglycosylated TBG was, at least in part, due to denatured TBG in the purified preparations. The specificity of the two RIAs is due to the existence of distinct and exclusive antigenic determinants in native TBG and denatured TBG which are probably located on the surface of the tertiary structure and internally at the primary structure of the molecule, respectively. Heat and acid pH treatments of serum produced a progressive loss in immunoreactive native TBG, proportional to the loss of T4-binding capacity. A reciprocal and quantitative increase in denatured TBG, as measured in the denatured TBG RIA, was found. T4 partially protected the native TBG from denaturation. Denatured TBG was detected in sera from normal adults. The mean value was 6.05 +/- 2.25 (+/- SD) micrograms/dl (n = 11). Similar values were found in 8 pregnant women, 5 men with familial partial TBG deficiency, and 15 hypothyroid 7 hepatic, and 8 renal failure patients.(ABSTRACT TRUNCATED AT 400 WORDS)

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“…The albumin fraction was diluted 1:5 with PBS to lower its salt content. Binding of T4 to albumin was assessed by a modification of the competitive binding technique employing Sephadex G-25 (21). 100 Ml of the diluted albumin fraction was added to several test tubes each containing 200 mg of Sephadex G-25 (medium) preequilibrated with PBS.…”

Section: Binding Studiesmentioning

confidence: 99%

“…Separate experiments were performed in the same range ofT4 concentrations but without serum proteins to estimate T4 binding by Sephadex. The calculation of the albumin-bound T4 was performed according to the original procedure (21), and the binding data were analyzed by the Scatchard method.…”

Section: Binding Studiesmentioning

confidence: 99%

Role of serum carrier proteins in the peripheral metabolism and tissue distribution of thyroid hormones in familial dysalbuminemic hyperthyroxinemia and congenital elevation of thyroxine-binding globulin.

Bianchi¹,

Iervasi²,

Pilo³

et al. 1987

J. Clin. Invest.

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To investigate the role of thyroxine-binding globulin (TBG) and albumin in the availability of thyroid hormones to peripheral tissues, comprehensive kinetic studies of thyroxine (T4) and triiodothyronine (T3) were carried out in eight subjects with familial dysalbuminemic hyperthyroxinemia (FDH), in four subjects with inherited TBG excess, and in 15 normals. In high-TBG subjects, the reduction of T4 and T3 plasma clearance rates (by 51% and 54%, respectively) was associated with normal daily productions; T4 and T3 distribution volumes were significantly reduced. In FDH subjects T4 clearance was less reduced (by 31%) than in high TBG; consequently T4 production rate was significantly increased (by 42%), T4 and T3 distribution volumes and T3 clearance rate were unchanged. Increased T3 peripheral production in FDH (by 24%) indicates that T4 bound to abnormal albumin is more available to tissues than T4 carried by TBG, thus suggesting an important role of albumin in T4 availability to the periphery.

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The Thyroxine-Binding Properties of Serum Proteins. A Competitive Binding Technique Employing Sephadex G-25

Cited by 28 publications

References 18 publications

The Kinetics of the Thyroid Hormones and the Peripheral Conversion Rate of Thyroxine to Triiodothyronine in Acute Liver Insufficiency under Experimental Conditions

The Kinetics of the Thyroid Hormones and the Peripheral Conversion Rate of Thyroxine to Triiodothyronine in Acute Liver Insufficiency under Experimental Conditions

Radioimmunoassays Specific for the Tertiary and Primary Structures of Thyroxine-Binding Globulin (TBG): Measurement of Denatured TBG in Serum*

Role of serum carrier proteins in the peripheral metabolism and tissue distribution of thyroid hormones in familial dysalbuminemic hyperthyroxinemia and congenital elevation of thyroxine-binding globulin.

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