The estimation of thyroxine in human plasma by an electrophoretic technique

Rp, Ekins

doi:10.1016/0009-8981(60)90051-6

Cited by 247 publications

(51 citation statements)

References 16 publications

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“…The competitive protein binding technique for the assay of hormones in biological fluids was introduced by Ekins (1960) for thyroxin [7]. Subsequently, Murphy [8,9] adapted the principle for the estimation of steroids.…”

Section: Discussionmentioning

confidence: 99%

Biological Activity of Corticotrophin Peptides With Homo-Arginine, Lysine or Ornithine Substituted for Arginine in Position 8

Tesser¹,

Maier²,

Schenkel-Hullinger³

et al. 1973

Acta Endocrinologica

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The steroidogenic and lipolytic activities of corticotrophin-(l-24)-tetracosapeptide and [Lys17.18]corticotrophin-(l-18)-octadecapeptide amide were compared with those of the corresponding analogues variously substituted in position 8 with homo-arginine, ornithine or lysine. Peptides substituted with homo-arginine showed a surprisingly high degree of biological activity; in all the tests performed, the loss o f activity due to the substitution did not exceed a factor of 3 to 10, w hile peptides sub stituted with ornithine or lysine in position 8 only showed residual biological activity or none at all, depending on the test system used. The results reported demonstrated that the presence of a guanidino group (arginine or homo-arginine side chain) in position 8 of the A CTH peptide is essential for the preservation of a high level of biological activity; the length of the aliphatic chain carrying the guanidino group is of minor importance. 56In p r e v io u s C om m u n ication s (Tesser & Schwyzer 1966; Tesser & Rittel 1969), the effect of the substitution of ornithine (cf. formulae, Table 1) for the arginine residue in positions 8, 17 and 18 of corticotrophin-(l-24)-tetracosapeptide (I)1 was described.It was shown that as far as the biological activity of the peptide is concerned the presence of a guanidino group in position 8 is more important than the presence of such a group in positions 17 or 18. The need for arginine8 had already been demonstrated earlier by Chung 8c L i (1967), who found that the biological activity of corticotrophin (1-17) heptadecapeptide amide substituted with lysine8 was remarkably weak as compared with that of the peptide containing arginine8. In addition, according to Geiger (1971) and Schwyzer et al. (1971) the active site of corticotrophin is located between positions 5 and 10; arginine8 is thus one of the amino acids composing the active centre.In the present studies, the effect of structural alterations in position 8 on steroidogenic and lipolytic activity has been further investigated.Peptides substituted in position 8 with homo-arginine, ornithine or lysine were compared with the unmodified peptide containing arginine. MATERIAL AND METHODSPeptides. -The synthesis of the analogues II and VI w ill be described elsewhere (Tesser et al., in prep.). Peptide I was prepared according to Kappeler & Schw yzer (1961); III was synthesized by Tesser & R itte l (1969). Peptides IV and V were prepared by a route analogous to that used in the synthesis of I (K am ber et al., unpublished results). The structures of the tested peptides are shown in Table 1.Steroidogenesis. -In vitro, adrenal slices were incubated for 2 h according to the method described by S affran & Schally (1955). The corticosterone content of the incubation medium was measured by acid fluorescence (G uïllem in et al. 1959).In vivo, the peptides were injected once intravenously into male rats hypophysectomized 24 h previously. The concentration of corticosterone in the plasma was determined as described by Desau...

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Section: Discussionmentioning

confidence: 99%

Biological Activity of Corticotrophin Peptides With Homo-Arginine, Lysine or Ornithine Substituted for Arginine in Position 8

Tesser¹,

Maier²,

Schenkel-Hullinger³

et al. 1973

Acta Endocrinologica

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“…was first used for the determination of serum thyroxine (T.) by Ekins (1960). In 1964, Murphy introduced the 'competitive protein-binding' method for hormones and this was rapidly applied to the determination of serum thyroxine (Murphy and Pattee, 1964).…”

Section: Methodsmentioning

confidence: 99%

Assessment of a Simple Technique for the Determination of Serum Thyroxine

Badman

Platten

1973

Ann Clin Biochem

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The diagnostic accuracy and precision of the Thyopac-4 Kit for measuring serum thyroxine is described. A simple work-saving modification to the procedure is suggested and a normal range established. The test is satisfactory for the diagnosis of hypo-and hyperthyroidism, correlating well with clinical assessments and the measurement of T, uptake. The precision of the technique is considerably better than that for P.B.I. and there are no time or temperature dependent stages. It can be scaled down for paediatric use.Work saving procedure

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Section: Discussionmentioning

confidence: 99%