Biomedical subjects

C Shaw

Publications and source records attributed to C Shaw.

At least 217 records · Page 12Linked to original sources

PubMed1992

Different relative abundance of neurotensin and neuromedin N in bovine ocular tissues.

Neurotensin (NT) and neuromedin N (NN) are regulatory peptides encoded by the same gene and located in tandem within a common precursor. Using specific radioimmunoassays for both peptides, their relative abundance in extracts of bovine ocular tissues has been examined. Within the retina, the molar concentration of NN was significantly higher (P less than 0.001) than that of NT. In contrast, within both choroid/sclera and iris/ciliary bodies, the molar concentration of NT was significantly higher (P less than 0.001) than that of NN. These data demonstrate that the theoretical molar ratio of 1:1, which would result from complete processing of both peptides from the common precursor, does not occur in any of the ocular tissues examined. Reverse phase HPLC of extracts of each ocular tissue confirmed the differential abundance of NT and NN. These data would suggest that the common NT/NN precursor is differentially-processed within bovine ocular tissues, a finding which may be of physiological significance.

Animals↗

PubMed1992

Isolation and primary structure of a novel chromogranin A-derived peptide, WE-14, from a human midgut carcinoid tumour.

The primary structure of a novel human chromogranin A-derived tetradecapeptide, WE-14, possessing N-terminal tryptophanyl (W) and C-terminal glutamyl (E) residues was isolated from a hepatic metastasis of an human ileal carcinoid tumour. Human and bovine WE-14 are structurally identical, while rat, mouse and porcine analogues exhibit 93% homology. WE-14 is flanked by paired basic residues (KR) in all known chromogranin A sequences.

Amino Acid Sequence↗

PubMed1992

Isolation and primary structure of an amphibian neurotensin.

Using a radioimmunoassay system employing an antiserum which recognises the common C-terminal tripeptide (YIL) of neurotensin (NT) and neuromedin N (NN), immunoreactivity was identified in extracts of brain (65.8 pmol/g), small intestine (44.2 pmol/g) and rectum (13.2 pmol/g) of the European common frog (Rana temporaria). No immunoreactivity was detected in extracts of stomach and skin. Reverse-phase HPLC analysis of each tissue extract resolved a single immunoreactive peptide with identical retention time in each case. The immunoreactive peptide was isolated by reverse-phase HPLC from brain extracts and an N-terminal pyroglutamyl residue was successfully removed enzymatically. The molecular mass of des(pyroglutamyl) frog NT, determined by plasma desorption mass spectroscopy, was 1440 Da. The primary structure of this peptide was determined by gas-phase sequencing and the calculated molecular mass, 1440.7 Da, was in close agreement with that derived by mass spectroscopy. The full primary structure of frog NT was established as: QSHISKARRPYIL. When compared with bovine NT, frog NT exhibits five amino acid substitutions in the N-terminal region, whereas the C-terminal hexapeptide sequence (RRPYIL), which mediates the classical biological effects of NT, is completely conserved. Amphibia thus possess a tridecapeptide NT which is analogous to that of higher vertebrates and considerable constraints on the primary structure of the C-terminal biologically-active core have existed for a vast evolutionary time span.

Amino Acid Sequence↗

PubMed1992

The primary structure and tissue distribution of an amphibian neuropeptide Y.

Neuropeptide Y (NPY) has been isolated and sequenced from brain extracts of the European common frog, Rana temporaria. Plasma desorption mass spectroscopy of the purified peptide indicated a molecular mass of 4243.3 Da which was in agreement with that deduced from the sequence (4243.7 Da), incorporating a C-terminal amide. The primary structure of frog NPY was established as: YPSKPDNPGEDAPAEDMAKYYSALRHYINLITRQRY-NH2. Frog NPY contains a single, highly-conservative amino acid substitution (Lys for Arg at residue 19) with respect to human NPY. NPY immunoreactivity was localised exclusively in nerves within the brain, pancreas and gastrointestinal tract and reverse-phase HPLC of extracts of these tissues resolved a single immunoreactive peptide of identical retention time in each case. The primary structure of NPY has therefore been highly-conserved over a considerable evolutionary time-span.

Amino Acid Sequence↗

PubMed1992

Neuropeptide F-immunoreactivity in the monogenean parasite Diclidophora merlangi.

The localisation and distribution of neuropeptide F (NPF)-immunoreactivity (IR) in the monogenean fish-gill parasite, Diclidophora merlangi, have been investigated by whole-mount immunocytochemistry interfaced with confocal scanning laser microscopy and, at the ultrastructural level, by indirect immunogold labeling. Using antisera directed to intact synthetic NPF (Moniezia expansa, residues 1-39) or to the C-terminal decapeptide (residues 30-39) of synthetic NPF (M. expansa), immunostaining was found throughout the central (CNS) and peripheral nervous systems (PNS), including the innervation of the reproductive system. Immunoreactivity was found to be more intense using the antiserum to the C-terminal decapeptide fragment of NPF. At the subcellular level, gold labeling of NPF-IR was found exclusively over the contents of dense-cored vesicles that occupied nerve axons of both the CNS and the PNS. The distribution pattern of immunostaining for NPF mirrored exactly that previously documented for the vertebrate pancreatic polypeptide (PP) family of peptides and for FMRFamide. This finding and the results of preabsorption experiments strongly suggest that NPF is the predominant native neuropeptide in D. merlangi and that it accounts for most of the immunostaining previously obtained with PP and FMRFamide antisera.

Animals↗

PubMed1992

Immunoreactivity to two specific regions of chromogranin A in the nervous system of Ascaris suum: an immunocytochemical study.

Antisera to a highly conserved region of chromogranin A (sequence KELTAE) and to a hexapeptide (sequence KGQELE) adjacent to the putative C-terminus of pancreastatin, a peptide whose sequence is found within the chromogranin A molecule, have been used to examine the localisation of immunoreactivity (IR) to these peptides in Ascaris suum. IR to both peptides was found in the nerve rings and nerve cords. In addition, KGQELE-IR was also observed in the pharyngeal neurones and in a network of fibres on the surface of the female gonoduct. The staining was specific in that it could be abolished by preincubation of the antisera with the appropriate antigen. The two antisera appeared to be staining different subsets of neurones, suggesting that (at least) two peptides were being recognised. The wide-spread distribution of IR to both peptides throughout the nervous system of the parasite suggests that the peptides carrying the epitopes recognised by the antisera are of fundamental importance to the functioning of the parasite's nervous system.

Amino Acid Sequence↗

PubMed1992

Characterization and localization of glutathione binding sites on cultured astrocytes.

Glutathione (GSH) binding sites found in brain white matter in a previous study using biotinylated GSH (Third IBRO World Congress Neurosci. Abstr., 1991, P59.17) suggested that there might GSH receptors on glial cells. In the present study, radioligand receptor assays were performed on cultured astrocytes using [35S]GSH. Scatchard analyses of saturation binding of [35S]GSH revealed two binding sites: Kd1 = 2.0 +/- 0.1 nM, Bmax1 = 89.5 +/- 1.5 fmole/2.2 x 10(5) cells and Kd2 = 12.8 +/- 0.4 nM, Bmax2 = 187.7 +/- 2.4 fmol/2.2 x 10(5) cells. The saturable and displacible high affinity [35S]GSH binding we have observed suggests that this binding is not due to GSH sequestration by uptake sites or to the association of GSH with GSH S-transferases or GSH peroxidases which have Kds in the microM range. Colloidal gold and immunofluorescence double labelling were used to visualize the binding sites at the cellular level. Positive colloidal gold decoration further suggests that these labelled binding sites are membrane receptors on astrocytes.

Animals↗

PubMed1992

Characterization and regulation of a high affinity [3H]CNQX labelled AMPA receptor in rat neocortex.

We have characterized a high affinity site of the alpha-amino-3 hydroxy-5-methyl-isoxazole-4-propionate (AMPA) receptor in in vitro living slices of adult rat neocortex using [3H]CNQX, and AMPA antagonist. [3H]CNQX labelled multiple binding sites with a Bmax of a high affinity site of approximately 470 fmol/mg protein and an apparent Kd of 11.3 nM. The high affinity site of the AMPA receptor could be down-regulated (36%) by 2 h preincubations in quisqualate, an AMPA agonist. Increases in electrical activity induced by a combination of veratridine and glutamate also led to an average decrease of the high affinity AMPA receptor number of 17%. In addition, preincubations with muscimol, a GABAA agonist, as well as glutamate agonists kainate and N-methyl-D-aspartate (NMDA) led to an average increase in high affinity AMPA receptor number of 17%, 14%, and 37%, respectively. The present results show that a ligand-gated high affinity AMPA receptor can be regulated by agonist stimulation as well as changes in neural activity.

6-Cyano-7-nitroquinoxaline-2,3-dione↗

PubMed1992

Age-dependent regulation of GABAA receptors in neocortex.

We have shown previously that GABAA receptors labelled with the antagonist [3H]SR95531 can be regulated in a living cortical slice preparation by agonists or changes in electrical activity. Due to the important role that receptor regulation may play in controlling neural activity, we have now investigated the regulation of GABAA receptors in neocortex at different stages in postnatal life. We found that regulation by agonist stimulation and increases in bioelectric activity is age-dependent in amount and, in the latter case, in direction. Using muscimol as an agonist we observed a GABAA receptor down-regulation of between 60 and 70% at 20-30 days of age; in adults muscimol gave an 11% down-regulation. A combination of veratridine and glutamate gave a peak down-regulation of 39% at 20 days postnatal, but an up-regulation of 58% in adults. These age-dependent effects may signal a role for receptor regulation in cortical neural critical period plasticity.

Aging↗

PubMed1992

The primary structure of peptide Y (PY) of the spiny dogfish, Squalus acanthias: immunocytochemical localisation and isolation from the pancreas.

1. Endocrine cells within islets, exocrine parenchyma and ductal epithelium in the pancreas of the spiny dogfish, Squalus acanthias, were immunostained with an antiserum to the C-terminal region of mammalian neuropeptide Y (NPY). 2. Radioimmunoassay of pancreatic extracts with the same antiserum detected immunoreactivity in the dorsal lobe (338 pmol/g) and ventral lobe (433 pmol/g). Reverse phase HPLC analysis of both extracts resolved a single immunoreactive peptide. 3. The primary structure of the isolated peptide was established as: YPPKPENPGEDAPPEELAKYYSALRHYINLITRQRY.NH2. 4. Peptide Y (PY) from Squalus acanthias is identical in primary structure to an NPY-related peptide isolated from the pancreas of Scyliorhinus canicula and has a 31/36 residue homology with porcine NPY. The 5 substitutions are highly-conservative.

Amino Acid Sequence↗

PubMed1992

Glutathione: new candidate neuropeptide in the central nervous system.

The physiological significance of glutathione in the mammalian central nervous system is still uncertain, although some evidence indicates that it may be an important regulatory peptide. In the present study, the distribution and characteristics of glutathione binding sites in the brain have been studied. Biotinyl-glutathione was synthesized as a probe to detect glutathione binding sites in the CNS. Specific glutathione binding sites in the brain were largely localized to the white matter, suggesting the presence of glutathione receptors on neuroglial cells. The colloidal gold technique and immunofluorescence double staining allowed the visualization of the receptor at the cellular level and thus demonstrated that there are glutathione receptors on cultured astrocytes. Glutathione applied to cultured astrocytes elicited increased levels of intracellular inositol-1,4,5-trisphosphate, suggesting that glutathione receptors were coupled to phospholipase C. The localization of glutathione receptors on astrocytes and the activation of a second messenger system by glutathione suggest that glutathione may be a neuropeptide in the central nervous system.

Animals↗

PubMed1992

Chromatographic and immunological characterisation of neuropeptide Y-like and pancreatic polypeptide-like peptides from the nematode Ascaris suum.

1. Immunoreactivity (IR) towards neuropeptide Y (NPY) and pancreatic polypeptide (PP) has previously been demonstrated in nematodes by immunocytochemistry (ICC). 2. The PP- and NPY-IR in the nematode parasite Ascaris suum were analysed using HPLC and radioimmunoassays (RIAs) specific for either peptide. 3. Quantitative RIA data on the distribution of these IRs in the parasite disagreed with ICC data suggesting that different tissue treatments used in the two techniques lead to different antigen availability. 4. Significant quantities of PP- and NPY-IR were found in the pseudocoelomic fluid suggesting a role for this medium in the transport of peptides. 5. The parasite possessed chromatographically-distinct PP- and NPY-IRs, with each IR being composed of several distinct molecules.

Animals↗

PubMed1992

Immunochemical characterisation of tachykinin immunoreactivity in the nervous system of the garden snail, Helix aspersa.

1. Circumoesophageal ganglia and foot muscle of the garden snail, Helix aspersa, were subjected to immunocytochemistry using antisera to the tachykinins, substance P (SP), neurokinin A (NKA), kassinin (KAS) and eledoisin (ELE). 2. Immunoreactivity in neuronal somata and fibres was detected only with the SP antiserum. 3. SP and NKA radioimmunoassays were performed on extracts of circumoesophageal ganglia. In common with immunocytochemistry, immunoreactivity was only detected with the SP antiserum. 4. Gel permeation chromatography of extracts resolved a single peak of immunoreactivity eluting slightly later than synthetic mammalian SP. Reverse-phase HPLC of immunoreactive fractions resolved two immunoreactive peptides representing oxidised and reduced forms of a single peptide. 5. These data suggest that the nervous system of H. aspersa contains a single tachykinin with C-terminal structural characteristics similar to mammalian SP.

Amino Acid Sequence↗

PubMed1992

Neuropeptide F: primary structure from the tubellarian, Artioposthia triangulata.

1. A neuropeptide exhibiting vertebrate pancreatic polypeptide immunoreactivity has been isolated and sequenced from extracts of the terrestrial turbellarian, Artioposthia triangulata. 2. This neuropeptide, designated neuropeptide F, consists of 36 amino acid residues terminating in a phenylalaninamide. 3. The full primary structure was established as: KVVHLRPRSSFSSEDEYQIYLRNVSKYIQLYGRPRF.NH2. The molecular mass, deduced from this sequence, was 4433 Da. 4. This neuropeptide exhibits C-terminal homology with neuropeptide F (Moniezia expansa) and with the vertebrate neuropeptide Y/pancreatic polypeptide superfamily of which it may represent a phylogenetic precursor.

Amino Acid Sequence↗

PubMed1992

The effect of a low-fat diet on hormone levels in healthy pre- and postmenopausal women: relevance for breast cancer.

It has been postulated that differences in the levels of circulating hormones may be the explanation for the epidemiological link between per capita dietary fat intake and the incidence of breast cancer. We have investigated this possible relationship in 19 postmenopausal, and 18 premenopausal women who completed a 4-week period on a diet aiming to reduce fat intake to around 20% of total kilocalories. 7-day dietary records revealed a significant decrease in dietary fat intake in both the pre- and postmenopausal groups (from 37.2% of calories from fat to 23.2% and from 37.9 to 24.3%, respectively). There was a minor increase in the level of sex hormone-binding globulin, and a small decrease in prolactin in the postmenopausal group, which were of borderline significance. There were no significant changes in total oestradiol (E2), or non-protein-bound (free) E2 concentrations. In the premenopausal group there were no significant changes in any of the hormone levels investigated.

Adult↗

PubMed1992

The performance of postencephalitic amnesic subjects on two behavioural tests of memory: concurrent discrimination learning and delayed matching-to-sample.

The performance of a group of three postencephalitic subjects with anterograde amnesia was examined on a series of concurrent visual discrimination problems and on a test of visual recognition, delayed matching-to-sample. These tests were chosen as they have been used to assess experimental models of anterograde amnesia in nonhuman primates. In comparison with a group of normal subjects the postencephalitic group were impaired on the more difficult concurrent discrimination problems. They also performed poorly on the matching-to-sample task when given lists of items to remember or given increased retention intervals. The pattern of performance of the postencephalitic group matched closely that of a group of Korsakoff subjects, indicating that these behavioural tests are equally sensitive to different types of anterograde amnesia.

Adult↗

PubMed1992

Neuropeptide F (Moniezia expansa): localization and characterization using specific antisera.

Immunocytochemical techniques used in conjunction with confocal scanning laser microscopy (CSLM) and electron microscopy have been used to demonstrate, for the first time, the distribution of the parasitic platyhelminth neuropeptide, neuropeptide F (NPF) in the cestode, Moniezia expansa. Antisera were raised to intact NPF(1-39) and to the C-terminal decapeptide of NPF(30-39). These antisera were characterized and validated for use in both immunocytochemistry and radioimmunoassay (RIA). NPF immunoreactivity (IR) was detected using both antisera throughout all of the major components of the central and peripheral nervous systems of the worm. The pattern of NPF-IR was found to mirror the IR obtained using a C-terminally directed pancreatic polypeptide (PP) antiserum and FMRFamide antisera; blocking studies using these antisera revealed that FMRFamide and PP antisera cross-react with NPF(M. expansa). RIA of acid-alcohol extracts of the worm measured 114 ng/g using the C-terminal NPF antiserum and 56 ng/g using the whole-molecule-directed antiserum. While the C-terminally-directed NPF antiserum cross-reacts with NPF-related peptides from other invertebrates, the whole-molecule-directed NPF antiserum is specific for NPF(M. expansa). The C-terminal NPF antiserum has potential for use in the identification and purification of NPF analogues from other platyhelminth parasites.

Amino Acid Sequence↗

PubMed1992

The apparent shape of afterimages in the Ames room.

When observers project afterimages of circular patterns onto a surface slanting away from them the images are reported as being oval in shape. In this paper it is reported that this does not occur when similar afterimages are projected onto the slanting rear wall of an Ames room. Instead of appearing as ovals, the afterimages remain circular. It appears as though the actually-slanted rear wall of the room not only looks as if it is normal to the line of vision, but also that it functions as if it was in such an orientation as far as a projection surface for afterimages is concerned. While these results are consistent with Emmert's law and with traditional accounts of shape and size constancy, they raise once again the age-old issue of whether the 'image on the retina' constitutes an object of perception that can be described in terms of its shape or size.

Adult↗