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Biomedical subjects

R Guillemin

Publications and source records attributed to R Guillemin.

At least 109 records · Page 6Linked to original sources
PubMed1981

Selective effects of somatostatin-14, -25 and -28 on in vitro insulin and glucagon secretion.

The widely occurring tetradecapeptide somatostatin (SRIF-14) has been variously implicated as a neurotransmitter, a neurohormone, a cybernin (local regulatory factor) and a hormone. In the first isolation of SRIF-14 from hypothalamic extracts and subsequent extracts of other tissues, peptides of higher molecular weight but with similar activity have been noted. Recently two such peptides have been characterized as the 28-amino acid SRIF-28 (from porcine gastro-intestinal tract and porcine and ovine hypothalamus and the 25-amino acid SRIF-25 (from ovine hypothalamus), each of which consists of an N-terminal extension of SRIF-14. We now report that SRIF-28 and SRIF-25 are more potent than SRIF-14 in the inhibition of insulin release, but that SRIF-14 preferentially inhibits glucagon release. This suggests that SRIF-28 and SRIF-25 are not mere biosynthetic precursors of SRIF-14 and that their differential release may be physiologically important.

Animals↗
PubMed1981

Isolation and chemical characterization of somatostatin-28 from rat hypothalamus.

A peptide with somatostatin-like immuno- and bioactivity has been isolated from an aqueous extract of 96 800 rat hypothalamic by means of immunoaffinity chromatography, gel filtration and reverse-phase high-performance liquid chromatography (HPLC). Chemical characterization by amino acid analysis, tryptic peptide mapping and retention behavior in two HPLC system showed that the peptide was indistinguishable from somatostatin-28 previously characterized from several species. This evidence suggests that rat hypothalamic somatostatin-28 is identical in structure to porcine and ovine somatostatin-28.

Amino Acids↗
PubMed1981

High biological activity of the synthetic replicates of somatostatin-28 and somatostatin-25.

We have isolated form extracts of ovine hypothalami two molecules characterized as somatostatin-28 and somatostatin-4-28 (referred to as somatostatin-25). They were reproduced by solid hase synthesis. In equimolar ratio and depending upon the experimental conditions, synthetic somatostatin-28 ans somatostatin-25 are 3-14 times more potent than somatostatin-14 to inhibit the basal in vitro secretion of growth hormone or as stimulated by prostaglandin (PGE2). In early studies in vivo, somatostatin-28 and somatostatin-25 are also more potent than somatostatin-14 in inhibiting the secretion of growth hormone acutely stimulated in the rat by injection of morphine; somatostatin-28 is also longer-acting than somatostatin-14. These results suggest that somatostatin-14, as originally isolated, is a biologically active fragment of a larger molecule of greater specific activity; it should be considered as another form of somatostatin with high biological activity present in some tissues and likely secreted y the tissues along with somatostatin-14 and possibly other somatostatin-peptides of diverse sizes.

Animals↗
PubMed1981

The regional distribution of gamma 3-melanotropin-like peptides in bovine brain is correlated with adrenocorticotropin immunoreactivity but not with beta-endorphin.

Immunoreactive (IR)-gamma 3-melanotropin (MSH), -adrenocorticotropin (ACTH) and -beta-endorphin in various areas of bovine brain were measured with their respective radioimmunoassays (RIA). The concentrations of IR-gamma 3-MSH were almost the same as those of IR-ACTH in most areas. Furthermore, in all brain regions, the concentrations of both peptides were lower than those of IR-beta-endorphin. The highest concentration of IR-gamma 3-MSH was found in hypothalamus, followed by thalamus, midbrain and striatum. Gel permeation chromatographic studies showed that the main gamma 3-MSH-like peptide in the hypothalamus, striatum and midbrain was a small form, whose molecular weight is about 4500. These brain gamma 3-MSH-like peptides were also found to be glycosylated.

Adrenocorticotropic Hormone↗
PubMed1981

Gonadocrinins: peptides in ovarian follicular fluid stimulating the secretion of pituitary gonadotropins.

A newly discovered small peptide purified from rat follicular fluid stimulates the pituitary to release FSH and LH in vitro as well as in vivo. Dialysates of crude acid extracts of ovarian follicular tissue and fluid from rats pretreated with PMS gonadotropin stimulate the secretion of both LH and FSH, but not PRL, GH, or TSH, in a pituitary monolayer culture system. This stimulating factor, named gonadocrinin for operational facility, is smaller than 3500 daltons; its biological activity disappears after treatment with trypsin. Gonadocrinin is not recognized by two-antisera binding the decapeptide LRF even though D-Phe2,D-Trp6-LR, an LRF analog antagonist, competitively inhibits the activity of ovarian gonadocrinin. Cultured rat granulosa cells also secret substances with gonadocrinin activity in vitro, indicating that the granulosa cells probably are in vivo the source of gonadocrinin. A crude preparation of gonadocrinin given iv to rats on the second day of diestrus induced secretion of LH comparable to that produced by a 250-ng LRF injection. Gonadocrinin has chemical characteristics different from those of LRF. When purified gonadocrinin or LRF was applied to an identical isocratic high pressure liquid chromatography system, LRF was eluted at a position different from that of gonadocrinin, indicating that, chemically, gonadocrinin is not identical to the hypothalamic decapeptide, LRF.

1-Methyl-3-isobutylxanthine↗
PubMed1981

Isolation and characterization of rat hypothalamic somatostatin-14.

A peptide with somatostatin-like immuno- and bioactivity has been isolated from 1165 rat hypothalami by using antisomatostatin affinity chromatography, gel filtration and reverse-phase high-performance liquid chromatography. The isolated peptide is indistinguishable from synthetic somatostatin-14 with respect to chromatographic properties and amino acid composition. We therefore propose that rat hypothalamic somatostatin-14 is identical in structure to somatostatin-14 found in other species.

Amino Acids↗
PubMed1981

Secretion pattern of pro-opiomelanocortin-derived peptides by a pituitary adenoma from a patient with Cushing's disease.

Fragments of the pituitary adenoma of a patient with Cushing's disease were maintained in defined culture medium. Immunoreactive (IR) ACTH, IR alpha-MSH, IR beta-lipotropin (beta-LPH), IR beta-endorphin, and IR gamma-MSHs secreted from the adenoma were studied with gel permeation chromatography and the respective RIAs. The adenoma secreted roughly equimolar quantities of IR beta-LPH plus IR beta-endorphin, IR gamma 3-MSHs, and IR ACTHs. It also secreted IR alpha-MSH as well as IR gamma 1-MSH, although in a much lower concentration than the above four peptides. The secreted gamma 3-MSH-like peptides were found to be glycosylated. The secretion pattern suggests that this particular adenoma processes the pro-opiomelanocortin molecule in pathways which encompass those of both the pars distalis and the pars intermedia.

Adenoma↗
PubMed1980

beta-Endorphin in obstetric analgesia.

Rapid and prolonged analgesia was obtained in all of 14 obstetric patients who received synthetic human beta-endorphin intrathecally at the time of delivery. Normal uterine contractions were maintained and all women were fully conscious and highly cooperative in the delivery process. No depression of respiration rate, cardiovascular or central nervous system was observed in any of the patients. Conditions of the infants evaluated by Apgar scoring were excellent. beta-endorphin must be administered intrathecally because it does not cross the blood-brain barrier; for the same reason, beta-endorphin cannot enter the central nervous system of the fetus as do opiates or other drugs commonly used as anesthetics or analgesics at the time of delivery.

Adolescent↗
PubMed1980

[High biological activity of the synthetic counterparts of hypothalamic somatostatin-28 and somatostatin-25].

We have isolated from extracts of ovine hypothalamus two molecules characterized as somatostatin-28 and somatostatin-4-28 (referred to as somatostatin-25). They were reproduced by synthesis. In equimolar ratios and depending upon the experimental conditions, synthetic somatostatin-28 and somatostatin-25 are 3 to 14 times more potent than somatostatin-14 to inhibit the basal in vitro secretion of growth hormone. These results suggest that somatostatin-14 as originally isolated, is a biologically active fragment of a larger molecule of greater specific activity, rather than somatostatin-28 being a precursor of the tetradecapeptide.

Animals↗
PubMed1980

Pituitary immunoreactive gamma-melanotropins are glycosylated oligopeptides.

Nakanishi et al. have recently characterised the complete sequence of the mRNA isolated from the intermediate lobe of bovine pituitary which codes for the 31,000 molecular weight (31K) precursor protein of corticotropin/beta-lipotropin (ACTH/beta-LPH). The corresponding amino acid sequence translated from this mRNA revealed in the cryptic region of the precursor protein a fragment sharing a common amino acid sequence with the alpha- beta-melanotropins (alpha-MSH, beta-MSH) and thus named gamma-MSH. To study whether this gamma-MSH fragment is also processed and released as a biologically active substance and to ascertain its location in the pituitary and possibly in the brain, we have raised antibodies to the synthetic replicate of gamma 3-MSH (ref. 2). We report here the detection of at least two gamma-MSH-like peptides in the pituitary using these antibodies in a radioimmunoassay (RLA) and, furthermore, evidence that these two peptides are glycosylated.

Carbohydrate Metabolism↗
PubMed1980

High-molecular-weight immunoreactive beta-endorphin in extracts of human placenta is a fragment of immunoglobulin G.

A high-molecular-weight protein with beta-endorphin- and adrenocorticotropin-immunoreactivities was isolated from extracts of human placenta after several purification steps, including immunoadsorption with a well-characterized antiserum raised to beta-endorphin. This protein was identified as the heavy chain of the human immunoglobulin class IgG1. These results have led to the recognition of homologies in the amino acid sequences of these physiologically unrelated molecules. They also suggest caution in accepting immunological competence as the sole criterion of the chemical identity of a ligand.

Amino Acid Sequence↗