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G I Chipens

Publications and source records attributed to G I Chipens.

At least 37 records · Page 2Linked to original sources
PubMed1989

[Cyclic analogs of ACTH fragments in self-stimulation and grooming behavior in rabbits].

In present study new cyclic fragments of ACTH EHFRWGKPVG--NH2 and KHFRWG--NH2 were investigated in organization of self-stimulation and grooming behaviour in rabbits. Intracerebroventricular injections of EHFRWGPVG--NH2 in doses of 0.1-2.5 g evoked significant increases of self-stimulation and in doses of 4-5 g suppressed self-stimulation in rabbits. The effect of other fragments KHFRWG--NH2 on self-stimulation was not statistically significant. Both fragments induced excessive grooming behaviour in rabbits. The effects of these fragments persisted of 48-72 hours.

Adrenocorticotropic Hormone↗
PubMed1989

Tritiation of [8-L-arginine, 9-desglycineamide] vasopressin.

Tritiated vasopressin analogue, [8-L-arginine, 9-desglycineamide]-vasopressin was prepared from its diiodo-derivative by means of catalytic reductive dehalogenation. The reaction products were purified by reversed-phase HPLC resulting in a labelled peptide with high specific radioactivity (629 TBq/mmol).

Arginine Vasopressin↗
PubMed1988

Determination of cyclopeptide conformations in solution using NMR data and conformational energy calculations.

The three-dimensional structure of the cyclic analogs of bradykinin and substance P C-terminal hexapeptide was studied using conformational energy calculations. Initial conformations for energy minimization were selected with the aid of the measured intensities of local nuclear Overhauser effects (NOEs) and other 1H-NMR data. Expected values of the 1H-NMR parameters for low-energy conformations of the cyclopeptides were calculated and compared with those observed experimentally using semiquantitative gradation of NOE intensities. Several low-energy structures of the cyclic bradykinin analog, possessing similar backbone conformations stabilized by two beta-turns, are in agreement with experimental data. None of the low-energy conformations of the substance P cyclic hexapeptide were in satisfactory agreement with the experimental set of NOEs. The agreement was achieved only by averaging of the calculated 1H-NMR parameters over several combinations of the low-energy conformations.

Bradykinin↗
PubMed1988

[Interaction of angiotensin analogs and fragments with rat adrenal cell receptors].

The binding of some modified angiotensin (AT) analogs and fragments to isolated rat adrenal glomerular cells was studied by radioreceptor analysis with a view of clarifying the role of C- and N-terminal amino acids in the binding of AT molecules to cell receptors. It was demonstrated that Arg2 and Val3 residues are of great importance for effective binding of the AT molecule to cell receptors. The presence of a free C-terminal carboxylic group in position 8 in the vicinity of the bulky lipophilic residue is a necessary condition for this process. The Asp and Asn residues located in position 1 of the AT molecule are not essential for the binding of the hormone molecule to adrenal cell receptors.

Adrenal Glands↗
PubMed1988

[A model for exploring afferent signals from the immune system to the nervous system].

Mechanisms of information transmission from the immune system to the nervous system have been studied. The results of the studies support the assumption that these signals can be transmitted by oligopeptides (the products of limited proteolysis) which are the fragments found in the active sites of many regulatory peptides of the nervous and immune systems. The testing of a synthesized tripeptide (Ser-Lys-Asp) has shown that it inhibits the antibody-forming cells in intact mice only in response to the administration of large antigen doses and exerts a protective effect against viral infection. When added to the culture of the incubated leukocytes from the peripheral blood of the oncological patients, the tripeptide lowers an increased or normal functional activity of natural killers. In rabbits, tripeptide administration brings about a complex long-lasting reorganization of bioelectrical activity in subcortical structures of the brain.

Animals↗
PubMed1988

[Synthesis and pharmacological properties of des-9-glycine analogs of [Orn8]vasopressin].

Three new analogues of vasopressin, viz. des-Gly9-[Phe2, Orn8]vasopressin, diglycyl-des-Gly9-[Phe2, Orn8]vasopressin, and diglycyl-des-Gly9-[Val4, Orn8]vasopressin, were synthesized to investigate the structure-function relationship. Hormonal (vasopressor, antidiuretic, uterotonic, galactogogic) activities of the new compounds were determined, their effect on elaboration and retention of the active avoidance behaviour in rats was studied.

Animals↗
PubMed1988

[Comparison of conformation characteristics of bradykinin and igercin molecules].

A certain resemblance of three-dimensional molecular organizations of the known peptide bioregulator bradykinin (Arg-Pro-Pro-Gly-Phe-Ser-Pro-Phe-Arg) and the tentative cytophilic centre of the human IgE igercin (Arg-Ala-Val-Ser-Val-Asn-Pro-Gly-Lys) existing along with their pronounced structural similarity was shown by means of energy calculations. This is, however, not the case with the "biologically active" bradykinin conformations suggested earlier.

Bradykinin↗
PubMed1987

[Synthesis and biological activity of peptides from interferon alpha A region 125-131].

Two peptides, IFN-(125-129) (RITLY-I) and [Arg7]IFN-(125-131) (RITLYLR-II), belonging to the putative immunologically active region of interferon alpha A (IFN) were synthesised by the solid-phase method. Both peptides suppress the delayed-type hypersensitivity reaction in vivo as assayed in mice. The peptide (II) either suppresses (0.01-0.1 mg/kg) or stimulates (approximately 1.0 mg/kg) antibody production in mice in response to sheep red blood cells.

Amino Acids↗
PubMed1987

[Structural similarity and functional activity of molecular fragments of staphylococcal enterotoxin B and thymopoietin II].

Structural similarity between Staphylococcus enterotoxin B and a thymus hormone, thymopoietin, has been revealed concerning thymopentin, one of active centres of thymopoietin. Fragments of enterotoxin B homologous to thymopoietin and their analogues were synthesized their immunological activity studied. Acetyl derivative of the fragment 225-229 of enterotoxin B increased infectional resistance and stimulated delayed type of hypersensitivity reaction.

Amino Acid Sequence↗
PubMed1986

[Structural-functional relations of short analogs of enkephalin].

The similarity of action of narcotic analgesics and opioid peptides is due to activation of a common opiate receptor as the primary step in initiating biochemical chains responsible for diverse morphine-like effects. The most widely used assays for opioid and analgesic activities are presented and evaluated. Approximately 180 short enkephalin analogues (di-, tri- and tetrapeptides), described in the literature, are systematized and their opioid and systemic analgesic activities compared with methionine-enkephalin and morphine as the reference compounds, respectively. The analysis of structure-opioid activity relationships among these enkephalin analogues substantiates the hypothesis that only a limited N-terminal region of the peptide molecule is essential for the binding of opioid peptides to the subclass of opiate receptors interacting with narcotic alkaloids (mu-receptors). An attempt has been made to identify minimal structural elements responsible for the mu-receptor activation. Shortening of the molecule and modification of its elements are examined with regard to the mu- and delta-receptor selectivity. It is emphasized that the aromatic structure of the C-terminal region of the peptide is not obligatory for the mu-receptor binding. Modifications of short enkephalin analogues which might confer them antagonistic properties are reviewed. The correlation between the ability of short enkephalin analogues to interact with mu-receptors and their antinociceptive properties is discussed along with some structural features pertinent to the analgesic effect after systemic administration of peptides. On the basis of this analysis, peptides containing no more than four amino acids are considered as the most probable morphine-like analgesics.

Animals↗
PubMed1986

[Study of bradykinin conformation in a dimethylsulfoxide solution by two-dimensional 1H-NMR spectroscopy].

The role of charged groups of the nonapeptide bradykinin in stabilization of its spatial structure in dimethyl sulfoxide solution was investigated. The signal assignment in the 1H-NMR spectra was achieved by means of two dimensional correlated spectroscopy (COSY) and nuclear Overhauser enhancement spectroscopy (NOESY). The changes in the NH and C alpha H proton chemical shifts of the Arg1 and Arg9 residues, variations both in temperature coefficients of chemical shifts of NH-resonances and coupling constants, as well as the appearance of additional NOE cross-peaks in NOESY spectra for d alpha N and d beta N 1H-1H distances were revealed by comparing the NMR spectra for two states--with the protonated C-terminal carboxyl group and deprotonated one. The experimental results are in agreement with the assumption that the conformation of the peptide in (CD3)2SO is stabilized by electrostatic interaction between the oppositely charged N- and C-terminal groups. The conformation with deprotonated alpha-carboxyl group is characterized by two beta-turns in the sequences Pro2-Pro-Gly-Phe5 and Ser6-Pro-Phe-Arg9.

Amino Acid Sequence↗
PubMed1986

[Interpretation of 1H-NMR spectra of the cyclic analog of kallidin in solutions].

1H-NMR resonances of [cyclo (10-1 epsilon)]kallidin (cyclo-KL) in (CD3)2SO and H2O have been assigned by combined analysis of two-dimensional phase-sensitive COSY and NOESY spectra. The presence of three slowly interchangeable conformers cyclo-KL I, cyclo-KL II, and cyclo-KL III, has been established, their population in (CD3)2SO being 25, 35 and 40%, respectively. Cyclo-KL I conformer possesses trans-configuration of all peptide bonds, but in the cyclo-KL II and cyclo-KL III conformers the Pro3-Pro4 and Arg2-Pro3 peptide bonds, respectively, have cis-configuration. In----solution, the following exchange occurs between the conformers: cyclo-KL II----cyclo-KL I----cyclo-KL III. The assignment of 1H-NMR signals of all the three cyclo-KL conformers has been carried out in H2O by gradual titration with (CO3)2SO. The conformer populations in H2O are 45, 25 and 30%, respectively.

Amino Acid Sequence↗
PubMed1985

[Synthesis and biological activity of a lysine-containing cyclic analog of [Leu5]enkephalin].

The cyclic analogue of [Leu5]enkephalin--cyclo (Lys-Tyr-Gly-Gly-Phe-Leu) and two corresponding linear hexapeptides with lysine residue attached to the N- or C-terminus of the molecule have been synthesized by classical methods of peptide chemistry. The addition of lysine residue to the N-terminus of cyclization of the molecule reduce the interaction of these analogues with both central and peripheral opiate receptors. The addition of lysine residue to the C-terminus of the molecule through the epsilon-amino group does not affect the interaction of the analogue with mu-receptors but reduces approximately tenfold its affinity for delta-receptors. All three analogues have analgesic potency similar to that of [Leu5]enkephalin as assayed after intracisternal administration to mice.

Animals↗
PubMed1985

[Synthesis of immunopoietins--new biologically active low molecular weight fragments of immunoglobulins G, M, E and A].

Low-molecular fragments of immunoglobulins IgG-(245-349) (Glu-Pro-Gln-Val-Tyr), IgM-(451-455) (Arg-Pro-Asp-Val-Tyr), IgA-(347-351) (Arg-Pro-Glu-Val-His), and IgE-(430-435) (Ala-Ala-Pro-Glu-Val-Tyr), potentially active immunoregulators of a novel type, have been synthesised by classical methods of peptide chemistry. This group of compounds, which in biological effects are similar to thymopoietin, was given the name of immunopoietins.

Amino Acid Sequence↗
PubMed1985

Cyclic analogues of bradykinin. IV. Structure-function relationships in the series of bradykinin cycloanalogues.

A study of the biological activity of six bradykinin and kallidin cycloanalogues has revealed that all of them exhibit prolonged hypotensive activity except the inactive cyclo-(omega-aminododecanoyl-omega-aminododecanoyl-bradykini n) (CADADB) when assayed in anaesthetized rats in vivo. The threshold dose of cyclo-bradykinin (CB) in these experiments was found to be 250 micrograms/kg of body weight. A single dose (500 micrograms/kg) of this cyclopeptide produces a decrease in the arterial pressure of rats up to 40 mm Hg for more than 2 h. The hypotensive action of other cyclopeptides under the same conditions is characterized by the following values: cyclo-[epsilon-(L-Lys1, Gly6)-bradykinin] (CLGB), alpha-L-Arg-cyclo-[epsilon-(L-Lys1, Gly6)-bradykinin] (ACLGB) and cyclo-epsilon-kallidin (CK) - 5 micrograms/kg, 40 mm Hg, over 2 h; cyclo-(omega-aminododecanoyl-bradykinin) (CADB) - 50 micrograms/kg, 250 micrograms/kg, 40 mm Hg, 35 min. Some cyclopeptides appeared to possess myotropic activity in vitro on isolated rat uterus preparations: CB (alpha = 0.52, pD2 = 7.86), CK (alpha = 1.0, pD2 = 7.56), CADB (alpha = 0.81, pD2 = 6.41). CLGB, ACLGB and CADADB failed to show myotropic activity. In contrast to CLGB and CADB, CK was hypotensive in dogs. CB acts as a weak antagonist of bradykinin (pA2 = 5.09 +/- 0.06) on rat uterus in vitro. It is believed that the hypotensive action within this series of compounds is primarily determined by the cycle size, whilst their myotropic activity is due to the presence of a "common" fragment Arg-Pro-Pro.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1984

Possible bioactive conformations of alpha-melanotropin.

By comparing the results of energy calculation for alpha-MSH and its semirigid analogues Ac-[ Cys4 , Cys10 ]-alpha- MSH4 -10-NH2, Ac-[ Cys4 , Cys10 ]-alpha- MSH4 -13-NH2, and [ Cys4 - Cys10 ]-alpha-MSH, a detailed description of two possible bioactive conformations for the 'specific' central site of alpha- MSH6 -9 is proposed representing variants of chain-reversal structure. A possible explanation of the rise in melanotropic activity of the latter two semirigid analogues is presented.

Melanocyte-Stimulating Hormones↗
PubMed1984

[Use of vasopressin the treatment of the paranoid form of schizophrenia].

Forty-seven males suffering from paranoid schizophrenia running a paroxysm-like progressive course were treated with the synthetic neuropeptide arginine-vasopressin, a hormone of the posterior lobe of the hypophysis. The therapeutic effect of the hormone was confirmed by a complex of clinical, laboratory and pathopsychological techniques. Both objective methods of investigation and subjective assessment of the patients demonstrated a high efficacy of the drug which was expressed in a marked psychoenergizing action, a beneficial effect on emotional disorders, a memory improvement and a favourable influence on the apatho-abulic manifestations.

Adult↗