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Biomedical subjects

N A Iudaev

Publications and source records attributed to N A Iudaev.

At least 37 records · Page 2Linked to original sources
PubMed1976

[Lipid-mobilizing activity of a synthetic peptide identical to 33-44 fragment of human growth hormone].

The lipid-mobilizing activity of a synthetic peptide, NH2-Phe-Glu-Glu-Ala-Tyr-Ile-Pro-Lys-Glu-Gln-Lys-Tyr-Ser-Phe-COOH, corresponding to the 31-44 amino-acid sequence of human growth hormone, was studied. The peptide stimulated lypolysis upon administration to fasted rats and during incubation with isolated epidiymal adiposed tissue of rat and perirenal adiposed tissue of rabbit. The lipid-mobilizing effect of the peptide,unlike the corresponding effect of the native growth hormone, developed fast and was markedly pronounced 15-30 min after the incubation was started. Direct dependence between the peptide dose logarithm and the effect studied was observed at concentrations of 0.01-10microng/ml during incubation with rat adipose tissue and at 0.001-0.1 microng/ml during incubation with rabbit tissue.

Adipose Tissue↗
PubMed1976

[Sex hormone reception in the human endometrium in normal and pathological pregnancy].

A study was made of reception of 17 beta-estradiol, progesterone, and testosterone in human endometrium during pregnancy. In the cytozol of the endometrium each of the sex steroids was bound by three different receptor components, two of which were represented by highly specific proteins. The maximal capacity of specific cytozol receptors to each of the sex steroids was measured in normal and pathological pregnancy; in the latter case the number of receptors to progesterone proved to be decreased. It is supposed that one of the specific binding components is necessary only under conditions of increased functional load upon the organ.

Cytosol↗
PubMed1976

[Comparison of the properties of L-threonine dehydratase isolated from the livers of intact, adrenalectomized or cortisol-treated rats].

L-Threonine dehydratase preparations were isolated from liver of intact, treated with hydrocortisone and adrenalectomized rats. These preparations had different properties in stability, sensitivity to proteases and kinetic patterns. The preparations possessed also serine dehydratase activity, and the ratio threonine: serine activities was modified during the procedure of enzyme purification. It appears that the hormones affect not only the amount of enzyme proteins, but the qualitative properties of these proteins.

Adrenalectomy↗
PubMed1976

[Pathways of corticosteroid biosynthesis in human adrenals (Itsenko-Cushing disease)].

Pregnenolone and its hydroxyl derivatives are of dominant importance in cortisol and corticosterone synthesis in human adrenals (hyperplasic glands and adenomes) removed in Itsenko-Kushing disease. Progesterone is produced in minimal amounts and is nearly not used for steroidogenesis. Participation of 17,21-dihydroxypregnenolone in cortisol synthesis is demonstrated. 17-hydroxyprogesterone is found not to take an important part as cortisol precursor. 21-hydroxypregnenolone is an essential intermediate in corticosterone synthesis. 11-hydroxyprogesterone does not participate in corticosteroids formation, since the rate of progesterone 11-hydroxylation in human adrenal mitochondria is minimal.

Adenoma↗
PubMedDate not supplied

[Specific binding of progesterone to the proteins of human endometrial cells].

A specific complex of protein-receptor with hormone, which had a sedimentation coefficient 3.8S, was formed in cell nuclei on incubation of endometrial tissue from pregnant woman with 3H-progestrone at 37 degrees C in vitro. In cell cytoplasm of endometrium the progesterone-protein complex was observed which sedimented at 6.8S and 4.2S. Progesterone was accumulated mainly in nuclei; lower concentrations of the hormone were found in cell cytoplasm of endometrium. Fractions of mitochondria, microsomes and ribosomes also bound the hormone but less distinct as compared with the nuclei. The formation of cytoplasmic complex of progesterone with protein-receptor occurred on incubation of endometrial cytoplasmic fraction with 3h-progesterone at 4 degrees C.

Cell Fractionation↗
PubMedDate not supplied

[Characteristics of testosterone-binding cytoplasmic components in the human endometrium and their interaction with chromatin].

The existence of macromolecules which specifically bind 3H-testosterone is demonstrated in the soluble fraction of human uterus endometrium. Testosterone receptors of endometrial cytosol are heterogenous and comprise the component with high affinity (Kd--2,9x10(-10) M) and low capacity (concentration of binding sites--0,5 pmoles per mg of protein) and the component with lower affinity and higher capacity (4x10(-9) M and 4 pmoles/mg of protein respectively). Incubation of sliced of endometrium at 37 (but not at 0 degrees) with 3H-testosterone results in the binding of the steroid by chromatin. On the other hand, testosterone-cytoplasmic receptor complex is able to associate with chromatin at 0 degrees. Chromatin did not bind free 3H-testosterone under these conditions. The existence of the receptor for testosterone in endometrial cells promoting its transport into the nucleus and binding with chromatin corroborates the previously shown specific action of testosterone on messenger RNA biogenesis in the uterus. Polyinductor model of regulation of gene expression in higher organisms by steroid hormones is discussed.

Binding Sites↗
PubMedDate not supplied

[Sequence of conversion of pregnenolone into androgens in virilizing adrenal glands in man].

Trace amounts of labelled pregnenolone were added to the slices of veriliscent tumor from human adrenal gland in order to study the stepwise conversion of the steroid into androstenedione, 11betaOH-androstenedione and their intermediats--17-alpha-OH pregnenolone, dehydroepiandrosterone, progesterone, and 17-alpha-OH-progesterone. The definite sequence was observed in the maximal incorporation of pregnenolone label into 17-alpha-OH-pregnenolone (2-5 min of incubation) leads to dehydroepiandrosterone (5-15 min) leads to androstenedione (10-20 min). Incorporation of the pregnenolone label into 17-alpha-OH-pregnenolone and dehydroepiandrosterone was distinctly higher than into progesterone and 17-alpha-OH-progesterone in all the experiments within all the studied periods of incubation. The data obtained suggest that in viriliscent tumors of adrenal gland conversion of pregnenolone into androgens proceeded as follows: pregnenolone leads to 17-alpha-OH-pregnenolone leads to dehydroepiandrosterone leads to androstenedione. When formation of androstenedione and 11beta-OH-androstenedione from pregnenolone and progesterone was analyzed during the experiment it was shown that 11-beta-OH-androstenedione was mainly formed via androstenedione and the hormone was the end product of the androgen synthesis.

17-alpha-Hydroxypregnenolone↗
PubMedDate not supplied

[Effect of ACTH on protein phosphorylation in rat adrenal ribosomes].

The authors studied the influence of ACTH on the steroidogenesis and 32P-labeled KH2PO4 incorporation into the ribosome proteins under conditions of incubation of the rat adrenal glands in vitro. 30 minutes before the incubation ACTH added into the medium stimulated corticosteroid biosynthesis by 116 +/- 26% and increased the radioactive phosphorus incorporation into the sum total ribosome proteins by 38 +/- 7%. Ribosome proteins were separated by electrophoresis in polyacrylamide gel at pH 4.5 into 30 fractions. 5--6 protein fractions proved to be phosphorylated during the incubation. ACTH altered the phosphorylation of individual protein fractions differently: there was stimulation in 2 fractions and inhibition of phosphorylation--in 3. It was revealed that, along with steroidogenesis, ACTH altered the phosphorylation of ribosome proteins. The change of the rate of ribosome phosphorylation was possibly one of the mechanisms with the aid of which the steroidogenic action of ACTH is realized.

Adrenal Glands↗
PubMedDate not supplied

[Adenylate- and guanylate cyclase systems in pathology of the adrenal glands].

The authors have summed up the results of a study of the activity of adenylate and guanylate cyclase system in the adrenals of patients with the Icenko-Cushing disease and syndrome and in the adrenals of experimental animals after unilateral adrenalectomy and in ACTH administration. It has been established that the biochemical mechanisms of compensatory hypertrophy of the adrenals in the normal and pathological tissue differ significantly. It has been shown for the first time that an increase in the basal activity of adenylate cyclase, resulting in the restoration of the initial hormonal level, is an obligatory condition for the compensation of organ function. Disorder in hormonal regulation of adenylate cyclase and diverse changes of the cyclase activity may indicate to the transition of tissue into a pathological state. Cyclic changes of the basal and stimulated activity of cyclases and protein kinases have been established for the first time in the adrenals of animals during administration of 2.5 units of ACTH for 5-40 days. The importance of detected changes in the mechanism of ACTH proliferative action is discussed.

Adenylyl Cyclases↗
PubMedDate not supplied

[Biological properties of synthetic somatostatin].

Complex work on the assessment of biological properties of somatostatin synthesized according to a new original method was carried out. Its inhibitory action on the TTH, growth hormone and insulin secretion was demonstrated in vivo and in vitro. As a rule, somatostatin effect was expressed against the background of stimulated hormone secretion, although basal secretion inhibition was observed with respect to insulin, The inhibitory action of somatostatin on the hormonal secretion was direct, not mediated through any regulating factors.

Animals↗