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Biomedical subjects

H R Morris

Publications and source records attributed to H R Morris.

At least 199 records · Page 11Linked to original sources
PubMed1987

Leukotriene release by endometrium and myometrium throughout the menstrual cycle in dysmenorrhoea and menorrhagia.

Endometrium and myometrium were collected at hysterectomy from 21 women with measured menstrual blood loss. Eight women complained of dysmenorrhea and the remaining 13 had pain-free periods. Specimens were obtained throughout the menstrual cycle (menstrual, n = 5; follicular, n = 4; early luteal, n = 3; mid-luteal, n = 5; late luteal, n = 4). Leukotriene C4, leukotriene D4 and leukotriene E4 release were examined using a short-term incubation technique. Endometrial leukotriene release, which was always significantly greater than myometrial release, changed throughout the menstrual cycle and the highest concentrations were found during menstruation. Endometrial, but not myometrial, leukotriene concentrations were significantly higher in tissues obtained from women with a complaint of dysmenorrhoea compared with those in tissue from pain-free women. No correlation was found between leukotriene release in either endometrium or myometrium and menstrual blood loss (range 15-457 ml).

Adult↗
PubMed1987

A direct action of human calcitonin gene-related peptide on isolated osteoclasts.

The calcitonin gene encodes a small family of peptides: calcitonin, calcitonin gene-related peptide (CGRP) and katacalcin. Whereas calcitonin is concerned with skeletal maintenance, the function, if any, of katacalcin is still unknown. In the present study we have assessed resorption of human cortical bone substrate by isolated rat osteoclasts and have shown that CGRP acts directly on the osteoclast to inhibit bone resorption. The three CGRP peptides (rat, human(alpha) and human(beta) caused an almost equivalent decrease in osteoclastic bone resorption and were approximately 1000-fold less potent than human calcitonin in this respect. The responses of human calcitonin and human CGRP(alpha) were additive. Furthermore, prior treatment with trypsin to destroy receptors abolished the responsiveness of osteoclasts to CGRP and calcitonin. The carboxyl- and amino-terminal fragments of CGRP were found not to inhibit bone resorption, suggesting that the whole molecule of CGRP is necessary for biological activity. We have therefore suggested that the calcitonin-like effects of CGRP, seen both in vivo in the rat bioassay and in vitro in organ cultures, are due to the direct action of CGRP on the osteoclast, probably mediated through the calcitonin receptor. Though it is unlikely that CGRP is involved in the regulation of plasma calcium, the peptide may be an important local regulator of bone cell function.

Animals↗
PubMed1986

Assignment of phosphorylation sites in buffalo beta-casein by fast atom bombardment mass spectrometry.

Fast atom bombardment mass spectrometry has been applied to the localization of phosphorylation sites in buffalo beta-casein. Two complementary strategies of identification are described. Phosphorylated residues in the tryptic peptide Tp 1 have been assigned by measuring the masses of peptide fragments obtained by enzymatic degradations. The phosphoserine residue in peptide Tp 2 has been identified by determining the intact molecular weight and confirmed by partial sequence information. This rapid and sensitive procedure appears of a great interest in structural studies of a wide range of post-translational modifications in proteins.

Amino Acid Sequence↗
PubMed1986

Investigation of the structure/activity relationship of human calcitonin gene-related peptide (CGRP).

The biological activities of calcitonin gene-related peptide (CGRP) enzymic digest fragments, chemically modified products and beta-CGRP have been compared to that of intact alpha-CGRP on rat isolated paired atria. Tryptic and chymotryptic digests both produced inactive fragments. Acetylation of the N-terminal amino acid (Alanine) or either of Lys 24 or Lys 35, resulted in reduced, but measurable, biological activity. Destruction of the disulphide bridge between Cys 2 and Cys 7 abolished biological activity. Substitution of several amino acids, Asp 3, Val 22 and Asn 25, with Asn, Met and Ser respectively (beta-CGRP), produced a peptide with similar biological activity to alpha-CGRP.

Amino Acids↗
PubMed1986

RIA/chromatographic evidence for novel opioid peptide(s) in Squilla mantis ganglia.

Proteins extracted from suboesophageal ganglia of Squilla mantis, an arthropod shown to be sensitive in vivo to opiates and to contain native opioid like peptide(s), were fractionated by gel filtration into three pools according to their molecular weight: A (Mr greater than 65,000), B (10,000 less than Mr less than 65,000) and C (Mr less than 10,000). None of these pools showed any immunoreactivity when radioimmunoassayed using antisera raised against Met-enkephalin either before or after sequential trypsin/carboxypeptidase B proteolysis. Further purification of pool C by HPLC followed by RIA using antibodies directed to Met-O-enkephalin,Leu-enkephalin,Dynorphin 1-13 and human beta-endorphin, showed only a trace amount of Met-enkephalin cross-reactivity (about 10 fmoles/mg of protein extract). No detectable amount of Leu- or Met-enkephalin was found after HPLC fractionation of proteolyzed pool B. Radioreceptor assay of HPLC fractions derived from trypsin/carboxypeptidase B treated pools B and C showed major areas of activity common to both pools, but nevertheless with differing retention times compared to the standard opioid peptides used.

Animals↗
PubMed1986

Human calcitonin gene related peptide: a potent endogenous vasodilator in man.

In addition to calcitonin and katacalcin, it is now known that the human calcitonin gene encodes a novel peptide called calcitonin gene related peptide (CGRP). In experimental animals, CGRP produces vasodilatation and complex changes in plasma calcium. We have now assessed its biological activity in man by infusing human CGRP (hCGRP) into six normal volunteers. hCGRP (545 pmol/min) caused the diastolic pressure to fall from 64 +/- 5 to 55 +/- 7 mmHg (P less than 0.05), the heart rate to increase from 61 +/- 7 to 87 +/- 5 beats/min (P less than 0.05) and the skin temperature to increase from 33.7 +/- 0.9 to 34.9 +/- 0.5 degrees C. Plasma noradrenaline increased from 481 +/- 126 to 835 +/- 65 pg/ml (P less than 0.05) and plasma adrenaline from 57 +/- 17 to 82 +/- 12 pg/ml (P less than 0.05). There were no significant changes in the albumin-corrected plasma calcium. hCGRP is thus a potent endogenous vasodilator in man and is in fact more potent than any other known vasodilator. Together with the observations that CGRP circulates in normal subjects at relatively high concentration (approximately 25 pmol/l) and that CGRP is present in perivascular nerves, this study suggests a possible role for CGRP in controlling peripheral vascular tone in man.

Adult↗
PubMed1986

Potent vasodilator activity of calcitonin gene-related peptide in human skin.

We have recently shown that the novel neuropeptide calcitonin gene-related peptide, CGRP, is a potent vasodilator. In this paper we report a detailed study of the effects of CGRP in human skin. CGRP induces a clearly defined, long-lasting erythema. We have measured the effect of CGRP on blood flow in human skin using a laser Doppler technique and have demonstrated increased local blood flow that persists for a number of hours. We compared the response of CGRP with other known vasodilators [histamine, prostaglandin (PG) E2, PGI2, substance P, and vasoactive intestinal peptide (VIP)] in the skin, and in all subjects the erythema induced by CGRP was more persistent than that induced by the other mediators tested. Except at high doses the local vasodilatation induced by CGRP was not associated with a wheal and flare as seen with histamine, substance P, and VIP. CGRP is an extremely potent vasodilator and if released into the circulation, or locally from peripheral nerve endings, it could have a role in the regulation of blood flow in both physiologic and pathologic conditions; CGRP may be the endogenous mediator of the flare in the triple response. A deficiency in CGRP secretion or action could be an important component of peripheral vascular disease. Some flushing reactions (e.g., those associated with medullary thyroid carcinoma) may result from circulating CGRP.

Adult↗
PubMed1986

The origin of circulating calcitonin gene-related peptide in the rat.

It is known that in addition to the calcitonin precursor the calcitonin gene also encodes a novel peptide, calcitonin gene-related peptide (CGRP). This potent vasodilator has been found in the circulation of man. This present study demonstrates that CGRP is also found in the circulation of the rat and that plasma CGRP comes from two different sources: the thyroid, a major source in old rats, and the perivascular nerves probably at all ages.

Adrenal Glands↗
PubMed1986

The effect of vasoactive intestinal peptide and calcitonin gene-related peptide on peptidoleukotriene release from platelet activating factor stimulated rat lungs and ionophore stimulated guinea pig lungs.

The effect of four neuropeptides and acetylcholine on the release of leukotrienes LTC4, LTD4 and LTE4 from platelet activating factor-stimulated rat lung and ionophore A23187-stimulated guinea pig lung, as detected by the combined use of HPLC and radioimmunoassay, was studied. Both vasoactive intestinal peptide and calcitonin gene-related peptide were found to inhibit the release of leukotrienes in both preparations. This effect was most marked in platelet activating factor-stimulated rat lung, where inhibition of LTC4 release was more pronounced than either inhibition of LTD4 or LTE4 production. The effect of vasoactive intestinal peptide on LTC4 biosynthesis was dose-related in rat lung. Neither substance P nor beta-endorphin were found to inhibit leukotriene release in rat lung. Vasoactive intestinal peptide inhibition of leukotriene release is independent from its actions on the muscarinic receptor, since acetylcholine was found to have no effect in the same preparation.

Acetylcholine↗
PubMed1985

Characterization of peptides cleaved by plasmin from the C-terminal polymerization domain of human fibrinogen.

The C-terminal region of the fibrinogen gamma chain is known to participate in several functional interactions including fibrin polymerization. This part of the molecule is retained on the gamma chain of fragment D (FgD) when fibrinogen is digested by plasmin in the presence of calcium to produce the fragment D-fragment E (FgD X FgE) complex but is lost if FgD is prepared in the absence of calcium. In an attempt to characterize the C-terminal polymerization domain we have used three techniques to examine this further degradation of FgD following the addition of EDTA and plasmin. Analysis of the digestion by sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed a progressive cleavage of the gamma chain to two small remnants. The polymerization-inhibitory activity of the whole digest was studied using acid-solubilized fibrin. A progressive loss of inhibitory activity was associated with gamma chain shortening, reaching greater than a 120-fold reduction at the end of digestion. The cleavage of peptides was followed by reverse-phase high performance liquid chromatography and the release of a characteristic peptide triplet was associated with gamma chain cleavage. Manual sequencing, amino acid analysis, and fast atom bombardment mass spectrometry established the three peptides as gamma 303-356, 357-373, and 374-405. These peptides have sequences in common with those peptides recently reported by other investigators to be potent polymerization inhibitors. However, when a mixture of the three peptides was added in a 200-fold molar excess to polymerizing fibrin, no inhibitory activity could be demonstrated. It is concluded that the C-terminal polymerization domain of fibrinogen may be an extended region which includes the sequence gamma 303-405, when this is contiguous with the remainder of the gamma chain.

Amino Acid Sequence↗
PubMed1985

Sequence and structure of a human glucose transporter.

The amino acid sequence of the glucose transport protein from human HepG2 hepatoma cells was deduced from analysis of a complementary DNA clone. Structural analysis of the purified human erythrocyte glucose transporter by fast atom bombardment mapping and gas phase Edman degradation confirmed the identity of the clone and demonstrated that the HepG2 and erythrocyte transporters are highly homologous and may be identical. The protein lacks a cleavable amino-terminal signal sequence. Analysis of the primary structure suggests the presence of 12 membrane-spanning domains. Several of these may form amphipathic alpha helices and contain abundant hydroxyl and amide side chains that could participate in glucose binding or line a transmembrane pore through which the sugar moves. The amino terminus, carboxyl terminus, and a highly hydrophilic domain in the center of the protein are all predicted to lie on the cytoplasmic face. Messenger RNA species homologous to HepG2 glucose transporter messenger RNA were detected in K562 leukemic cells, HT29 colon adenocarcinoma cells, and human kidney tissue.

Amino Acid Sequence↗
PubMed1985

An HPLC/push-pull perfusion technique for investigating peptide metabolism.

We have combined the push-pull perfusion of radiolabelled peptide, with reverse phase--HPLC procedures as a valuable method for monitoring peptide metabolism in the CNS. This model not only permits studies on metabolism of neuropeptides at specific sites in the CNS, but more importantly, allows (unlike in vitro methods) the study to be made under the appropriate physiological conditions. We have demonstrated unambiguously for the first time, the metabolism of CCK-8 in situ.

Animals↗
PubMed1985

Calcitonin gene-related peptide: potent vasodilator and major product of calcitonin gene.

In addition to calcitonin and katacalcin, the human calcitonin gene encodes a novel peptide--calcitonin gene-related peptide (CGRP)--a potent vasodilator. A sensitive and specific radioimmunoassay was developed to study plasma levels of CGRP in normal subjects. CGRP circulates at five times the concentration of calcitonin, suggesting that it may be an important physiological regulator of vascular tone and blood flow.

Adult↗
PubMed1985

Location of the adenylylation site in T4 RNA ligase.

The purification of the enzyme T4 RNA ligase is described from an Escherichia coli strain, KR54, in which the RNA ligase gene (g63) has been inserted into the plasmid pDR540 for inducible expression of g63 from the tac promoter. Adenylylation of the purified enzyme with [14C]rATP followed by digestion with chymotrypsin yielded an adenylylated peptide, the identity of which was determined by fast-atom-bombardment mass spectrometric analysis. The results show that the AMP residue is bound covalently to the lysine at position 99 of the RNA ligase protein sequence.

Binding Sites↗
PubMed1985

A new method for rapid assignment of S-S bridges in proteins.

A new method for complementing existing protein chemical techniques for the assignment of S-S bridge positions in amino-acid sequences is described. The principle of the method is the direct examination of the masses of protein fragments, obtained by chemical or enzymatic degradation. Proteins are digested under conditions known to minimise disulphide reduction and reshuffling, and the unfractionated digest is examined directly by high field magnet (or other high mass) fast atom bombardment or Californium mass spectrometry. Disulphide linked peptides are identified from their unique masses, and by comparison with the spectrum of digested and reduced samples in which the signal corresponding to the S-S linked peptide(s) is replaced by two signals corresponding to the respective thiol peptide components, if INTER-bridged, or shifted by two mass units (dithiol) if INTRA-bridged. This rapid procedure has considerable potential in assisting with studies on the primary structure of proteins, in crystallographic studies and the monitoring of denaturation/renaturation of recombinant proteins.

Carboxypeptidases↗
PubMed1985

beta-Endorphin in neuroblastoma x glioma hybrid cells.

Acid extracts from mouse Neuroblastoma x rat Glioma hybrid cells have been purified by means of Sep-Pak C-18 and fractionated by high performance liquid chromatography. Each fraction has been submitted to a sensitive beta-endorphin radioimmunoassay and an immunoreactivity peak at camel beta-endorphin retention time was found.

Animals↗