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Biomedical subjects

Iu P Shvachkin

Publications and source records attributed to Iu P Shvachkin.

At least 19 recordsLinked to original sources
PubMed1993

[Synthesis of somatostatin in Escherichia coli cells: isolation and characteristics].

A synthetic gene coding for somatostatin-14 (SST) was cloned in plasmid expression vectors in frame with the chloramphenicol acetyl transferase (CAT) gene, both genes being divided by a Met residue. The hybrid gene was expressed under the control of the CAT gene promoter (Pcat) or the tryptophan operon promoter (Ptrp). Them fused genes gave insoluble polypeptide products amounting from 5% of the total cellular protein under constitutive biosynthesis conditions (Pcat) to 30% upon induction (Ptrp). SST was liberated from the fused polypeptide by treatment with cyanogen bromide, purified to homogeneity by gel-filtration and reverse phase HPLC, and finally refolded by dilution and air oxidation. The renaturated recombinant SST showed the specific biological and immunological activities of the native peptide.

Amino Acid Sequence↗
PubMed1989

[Conformation-activity relations of dermorphin and its pentapeptide analogs].

Low-energy peptide backbone structures of dermorphin (DM), amide of its N-terminal pentapeptide (DM 1-5) and DM 1-5 analogues with substitutions of Gly4 for Leu, D-Gln, Aal or Tal were determined by energy calculations. The above analogues were shown to possess different affinities toward opiate receptors of mu-type. The comparison of low-energy backbone structures of DM, DM 1-5 and its analogues resulted in development of the dermorphin "biologically active" conformation being characteristic of its binding with mu-type receptors. The specific binding of dermorphin to this receptor apparently depends on the conformation of the whole N-terminal pentapeptide.

Amino Acid Sequence↗
PubMed1989

[The antioxidant activity of cyclohistidylproline].

A cyclohistidyl-proline, cyclopeptide possessing a hormonal and neurotrophic activity is shown to be an inhibitor of the (Fe + ascorbic acid)-induced peroxidation of membrane lipids, its effect being dependent on its concentration. Inhibition of the malondialdehyde formation by cyclohistidil-proline is accompanied by protection of the membrane bound Ca-pump. In the test of the free radical cumole oxidation antioxidative effect of cyclohistidyl-proline is 4 times higher than that of the hydrophilic antioxidant carnosine. After peritoneal injection of cyclohistidil-proline (15 mg/kg of body weight) to rats the stationary level of thiobarbituric acid reactive products in rat brain or serum is pronouncedly decreased, this effect being in progress up to 6 h after injection. Antioxidative action of cyclohistidyl-proline suggests to be on the basis of a variety of its biological effects.

Animals↗
PubMed1985

[Response of the secretory glands of the stomach to peptide injection into the hypothalamus, caudate nucleus and amygdala].

In chronic experiments on dogs, microapplication of neurotensin into the hypothalamus or amygdala combined with histamin or pentagastrin stimulation of the stomach secretory function significantly reduced the stomach secretion. Microapplication of somatostatin into the hypothalamus or amygdala combined with i.v. administration of pentagastrin increased two-fold the stomach secretion. The same increasing effect occurred after microapplication of methionin or leucin-5-enkephalin retroanalogue into the hypothalamus or amygdala.

Amygdala↗
PubMed1985

[A new structural analog of human insulin--glycine-B30-insulin].

Enzymatic-chemical preparation of glycine-B30-insulin, a new structural analog of human insulin has been performed. The new analog differs from the natural hormone by a substituted ThrB30 residue in the glycine residue. The biological activity of the glycine-B30-insulin as measured by the mouse convulsion assay is 100%.

Animals↗
PubMed1984

[A new structural analog of human insulin-- [glutamine-B30] insulin].

A new structural analogue of human insulin, [glutamine-B30]insulin, has been prepared by enzymatic-chemical means. This analogue differs from natural hormone by substitution of the ThrB30 residue. Biological activity of the [glutamine-B30]insulin is 100% in the mouse convulsion assay.

Animals↗
PubMed1984

[Functional state of the thyroid and its regulatory system in tumor-bearing animals].

A comparative study of labelled thyroxine and iodine accumulation was carried out in the thyroid endocrine complex under endoliquor and intraabdominal introduction of thyrotropic hormone (TTH) and thyrotropin-releasing-factor (TRF) in rats with transplantable and induced tumours as well as in intact animals. A sharp decrease of the system response to TRF in tumour-bearing animals was established. The incorporation of labelled thyroxine introduced into the thyroid gland tissue and posterior region of the hypothalamus is found to be lower under the tumour growth. The character of changes causing the disturbances in the activity of the thyroid gland should be taken into account in an attempt to normalize the gland activity. The normalization should be based on the complex influence directed to all the links of the hypothalamus-pituitary thyroid gland system.

Animals↗
PubMed1983

[Influence of thyroliberin and its analogs with different hormonal activity on the pharmacological effects of ethanol].

TRH and its two analogs with modified hormonal activity were examined for the capacity to antagonize acute and chronic effects of ethanol in mice. It has been demonstrated that L-pyroglutamyl-L-seryl-L-leucinamide, an analog of TRH, that does not affect the secretion of TSH and decreases prolactin production has the same capacity as TRH to reduce the time of ethanol narcosis but produces a lesser effect on the ethanol-induced fall of rectal temperature. Both the drugs did not affect the ethanol-altered ability of mice to hold on the rotating bar. Methyl ether of TRH, a hormonally inactive analog, was ineffective as shown by all the tests. Neither TRH nor its analogs changed the development of tolerance to chronic administration of ethanol, recorded by the rotating bar test and rectal temperature drop.

Animals↗
PubMed1983

[Effect of methionine-5-enkephalin retroanalog on gastric secretion].

Alteration of the enkephalin molecule by means of synthesis of peptide with opposite direction of peptide connections between residues of aminoacids (retro--methionin--5--enkephalin) entailed some changes of its action in respect to activity of the stomach secretory cells in dogs. Thus, for instance, the retroanalogue methionin--5--enkephalin proved to be a more efficient activator of gastric secretion induced with pentagastrin.

Animals↗
PubMed1983

[Natural peptides and their analogs. XXXI. Synthesis and properties of the retro-analog of methionine-5-enkephalin].

The synthesis of retro-analog of methionine-5-enkephalin was performed. This peptide is an isomer of the natural methionine-5-enkephalin, but differs from it by opposite direction of peptide linkages between the amino acid residues. The influence of retro-analog on prolactin secretion was studied both in vivo and in vitro. The retro-analog was found to stimulate the prolactin secretion more effectively than methionine-5-enkephalin.

Animals↗
PubMed1982

[Sensitivity of hypothalamic neurons to beta-endomorphin, met-enkephalin, and thyroliberin].

A study was made of susceptibility of hypothalamic neurons to beta-endorphine, thyroliberin and met-enkephalin applied microiontophoretically. The opioids were shown to exert a primarily unidirectional effect on the same neurons irrespective of the fact that the inhibitory action of beta-endorphine was more pronounced. The nalorphine-competitive antagonist of the opiates removed the met-enkephalin-induced inhibition. Unlike opioids, thyroliberin largely activated the test neurons. The possibility of neuropeptide participation in the control of gonadotropic function of the pituitary is discussed.

Animals↗