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Biomedical subjects

A Otaka

Publications and source records attributed to A Otaka.

At least 73 records · Page 4Linked to original sources
PubMed1991

Solid phase peptide synthesis of human endothelin precursor peptides using two-step hard acid deprotection/cleavage methods.

Syntheses are described for the putative human and porcine biosynthetic precursors (hET-38 and pET-39) of endothelin, with the sequence previously deduced from human- and porcine-cDNA coding for preproendothelin. The Boc based solid phase synthetic method was applied, followed by weak hard acid, trimethylsilyl bromide, cleavage. The peptide removal from the resin was optimally accomplished with hydrogen fluoride. Disulfide bridges were formed by air-oxidation, and the linkage modes determined by enzymic (Endoproteinase Asp-N) digestion and HPLC. Five additional C-terminally elongated endothelin homologs were also synthesized. For alternative synthesis of pET-39, the use of trimethylsilyl trifluoromethanesulfonate for the removal of peptide from the resin generated a major side product, which was characterized. hET-38 was found to be less effective in vitro, when compared to endothelin. The vasoconstrictor activity in vitro of other related peptides was comparable to that of hET-38.

Amino Acid Sequence↗
PubMed1990

Microenzyme immunoassay for the measurement of brain natriuretic peptide (BNP)-like immunoreactivity in porcine plasma.

A sensitive and specific microenzyme immunoassay (EIA) procedure for porcine brain natriuretic peptide (BNP)-like immunoreactivity has been developed. Enzyme-labeled antigen was prepared by conjugation of synthetic BNP with beta-D-galactosidase using N-(epsilon-maleimidocaproyloxy)succinimide method. Using a second antibody-coated immunoplate, the minimum amount of BNP-like immunoreactivity (BNP-LI) detectable by this assay system was 1.6 fmol/well. When porcine BNP-LI in porcine plasma was assayed by the present method levels between 1 and 8 pmol/l were detected. Gel filtration of porcine plasma extracts on Sephadex G-25 revealed the presence of two immunoreactive peaks; one eluted at a position identical with that of BNP-26 and the other eluted earlier, close the position of BNP-32.

Amino Acid Sequence↗
PubMed1989

Immuno-affinity purification of specific antibodies against human gastrin releasing peptide (h-GRP) by the h-GRP(1-8)-linked polydimethylacrylamide resin.

A new method for immuno-affinity purification of specific antibodies against human gastrin releasing peptide(h-GRP) was developed. The antiserum GP(No. 6201) elicited by h-GRP-BSA conjugate was heterogeneous and reacted not only with h-GRP and its fragments but also partially with other structurally related peptides, such as other GRPs (porcine, canine, and chicken), bombesin, and neuromedin-C. To obtain specific antibodies against human GRP, antiserum GP was purified by column chromatography on the amino-terminal octapeptide h-GRP(1-8)-linked polydimethylacrylamide resin. The antibody thus obtained was highly specific to amino-terminal sequence of h-GRP and hardly reacted with other GRPs (porcine, canine and chicken), bombesin, and even carboxy-terminal h-GRP fragments in ELISA.

Acrylamides↗
PubMed1989

Immuno-affinity purification of specific antibodies against vasoactive intestinal polypeptide (VIP) on VIP (1-10)-linked polydimethylacrylamide resin.

A novel method for immuno-affinity purification of specific antibodies against amino-terminal (N-terminal) porcine vasoactive intestinal polypeptide (p-VIP) was developed. The antiserum VP (No. 6203) elicited by p-VIP-immunoglobulin G (IgG) conjugate was heterogenous and reacted not only with the N-terminal fragments of p-VIP but also with carboxy-terminal (C-terminal) fragments. To obtain specific antibodies against the N-terminal fragment of p-VIP, antiserum VP was purified by column chromatography on N-terminal decapeptide (p-VIP 1-10)-linked polydimethylacrylamide resin. The antibody thus obtained was highly specific to the N-terminal sequence of p-VIP and hardly reacted with the C-terminal fragments of VIP in enzyme-linked immunosorbent assay.

Antibodies↗
PubMed1988

Studies on peptides CLVIII. Model experiments for the synthesis of open-chain unsymmetrical cystine-peptides.

Treatment of a mixture of Cys(R)(O) and Cys(R') with an acid was found to generate cystine in fairly good yields, when suitable R, R', and an acid were selected. An unsymmetrical cystine peptide was prepared by treatment of a mixture of Z(OMe)-Cys(R) (0)-Ala-NH2 (R = Acm or MBzl) and Z(OMe)-Cys(MBzl)-Gly-OBzl with TFA or 1 M TFMSA/TFA3. Oxytocin was obtained in an excellent yield by TFA treatment of the protected peptide containing Cys(Acm)(0) and Cys(MBzl). Thus, formation of the disulfide bond was found feasible at the position of Cys(R) (0).

Cystine↗
PubMed1987

Calcitonin gene-related peptide promotes mechanical nociception by potentiating release of substance P from the spinal dorsal horn in rats.

In vitro superfusion with capsaicin (5 X 10(-7) M) of slices of the dorsal half of the rat spinal cord produced a significant increase in a release of immunoreactive substance P (iSP). Calcitonin gene-related peptide (CGRP: 10(-6) M) significantly potentiated the capsaicin-induced release of iSP. On the other hand, when CGRP (5 nmol/rat) was intrathecally injected, the peptide produced a significant hyperalgesia to mechanical noxious stimuli (pinching the hind paw), but aversive responses and potentiation of substance P-induced aversive responses were never observed. These findings suggest that in the rat spinal dorsal horn, CGRP potentiates the release of substance P from the primary afferent terminal and promotes the transmission of nociceptive information induced by mechanical noxious stimuli.

Animals↗
PubMed1986

Human calcitonin gene-related peptide possesses weak inhibitory potency of bone resorption in vitro.

Synthetic human calcitonin gene-related peptide (CGRP) was examined for the action on the bone in vitro. Human CGRP inhibited bone resorption stimulated by both human parathyroid hormone and basal. The mode of inhibitory action of human CGRP seemed to be similar to that of calcitonin and the relative potency of human CGRP to inhibit bone resorption is one five-hundredth of that of human calcitonin. Thus, a novel pharmacological action of CGRP was demonstrated.

Animals↗
PubMed1986

Binding sites of calcitonin gene-related peptide (CGRP): abundant occurrence in visceral organs.

Calcitonin gene-related peptide (CGRP) is a novel peptide amide of 37 amino acid residues, which was first identified as the product of alternative processing of RNA transcripts of the calcitonin gene in humans and rats. Using 125I-human CGRP (hCGRP) as the binding ligand and hCGRP or salmon calcitonin (sCT) as the specific inhibitor of binding, it was examined how the receptor-like binding sites distribute among rat tissues including the nervous system, which is already known to contain binding sites in discrete regions. Some visceral organs (liver, spleen and lung) and possibly the bone marrow of Wistar male rats (8-10 weeks old) were found to be relatively rich in these binding sites. The following parameters were calculated by Scatchard analysis of binding data for the cerebellum, spleen and liver; KD (nM) and Bmax (fmol/mg protein) were 0.61 and 408, 1.08 and 858, and 0.89 and 356, respectively. In these three tissues, both hCGRP and sCT were able to completely suppress the specific binding; the IC50s (nM) of hCGRP for the cerebellum, spleen and liver were 2.57, 2.29 and 3.02, respectively, and the IC50s (microM) of sCT 2.69, 0.41 and 1.78, respectively. The results obtained herein strongly suggest the physiological function of CGRP in these visceral organs including bone marrow.

Animals↗
PubMedDate not supplied

Possible mechanisms of positive inotropic action of synthetic human calcitonin gene-related peptide in isolated rat atrium.

The effect of synthetic human calcitonin gene-related peptide (hCGRP) on the isolated and electrically driven left atria of rats were investigated. The peptide at concentrations of 3 X 10(-9)-3 X 10(-7) M produced positive inotropic effects on the left atria in a dose-dependent manner. Verapamil (10(-5) M) and adenosine (10(-4) M) reduced the positive inotropic effect of hCGRP at concentrations of 3 X 10(-9) and 3 X 10(-8) M, but not at that of 3 X 10(-7) M. Ouabain (5 X 10(-5) M) inhibited the effect of hCGRP in concentrations of 3 X 10(-7) and 3 X 10(-8) M, but not in that of 3 X 10(-9) M. Simultaneous pretreatment with verapamil (10(-5) M) and ouabain (5 X 10(-5) M) suppressed the positive inotropy by hCGRP at all concentrations tested. On the other hand, tetrodotoxin (10(-6) M) potentiated only the positive inotropic effect of 3 X 10(-7) M hCGRP. Metoprolol (10(-7) M) and theophilline (10(-3) M) did not affect the inotropic effect of hCGRP. These results suggest that the positive inotropic effect of hCGRP is not mediated by beta-adrenoceptors but by two distinct mechanisms of action, which was inhibited by verapamil but not by ouabain (facilitation of Ca++ influx in lower concentrations of hCGRP) and which was blocked by ouabain but not by verapamil and potentiated by tetrodotoxin (inhibition of Na+/Ca++ exchange mechanism at higher concentrations of hCGRP).

Adenosine↗