Search PubMed⌕ Search

Biomedical subjects

C Shaw

Publications and source records attributed to C Shaw.

At least 253 records · Page 14Linked to original sources
PubMed1991

The ultrastructure and immunogold labelling of pancreatic polypeptide-immunoreactive cells associated with the egg-forming apparatus of a monogenean parasite, Diclidophora merlangi.

An electron microscopical examination has been made of the fine structure and disposition of pancreatic polypeptide immunoreactive cells associated with the egg-forming apparatus in Diclidophora merlangi. The cell bodies are positioned in the parenchyma surrounding the ootype and taper to axon-like processes that extend to the ootype wall. The terminal regions of these processes branch and anastomose and, in places, the swollen endings or varicosities form synaptic appositions with the muscle fibres in the ootype wall. The cells are characterized by an extensive GER-Golgi system that is involved in the assembly and packaging of dense-cored vesicles. The vesicles accumulate in the axons and terminal varicosities, and their contents were found to be immunoreactive with antisera raised to the C-terminal hexapeptide amide of pancreatic polypeptide. It is concluded that the cells are neurosecretory in appearance and that, functionally, their secretions may serve to regulate ootype motility and thereby help co-ordinate egg production in the worm.

Animals↗
PubMed1991

Rat small intestinal morphology and tissue regulatory peptides: effects of high dietary fat.

Sprague-Dawley rats (3 weeks old) were fed on isoenergetic diets in which 40% of the total energy was provided as fat either in the form of butter (high saturated fat), olive oil (high monounsaturated fat) or maize oil (high polyunsaturated fat), with one group on low-fat (10% of total energy) standard diet as a control. Animals were killed after 8.4 (se 0.8) weeks by cardiac puncture. Similar pieces of jejunum and ileum were prepared for morphometric studies. Extracts of tissue from the proximal and distal segments of the whole small intestine from four animals per group were assayed using established techniques for enteroglucagon, motilin, neurotensin, somatostatin, substance P and vasoactive intestinal peptide (VIP). We found that maize oil and olive oil increased villus height: crypt depth ratio in both jejunum and ileum. Maize oil increased tissue concentrations of somatostatin (P less than 0.05) and substance P (P less than 0.005) in the proximal segment. Both maize oil and olive oil increased tissue concentrations of neurotensin and substance P (P less than 0.005) in the distal segments. These observations may explain the improvement of intestinal absorption of fluid following supplementation with polyunsaturated fat.

Animals↗
PubMed1991

Transcatheter detachable balloon embolotherapy for catheter-induced pulmonary artery pseudoaneurysm.

Pulmonary artery pseudoaneurysm formation may be due to various etiologies, including trauma, pulmonary artery catheterization, infection, and tumor. Transcatheter embolization is a nonsurgical management technique that may be utilized in many of these patients to occlude the affected artery and to prevent further extravasation. Recently, two patients with pulmonary artery pseudoaneurysm formation after balloon-tipped catheter placement were successfully managed with transcatheter embolotherapy with detachable silicone balloons. The article describes their diagnosis and management.

Aged↗
PubMed1991

Neuropeptides in psoriasis: an immunocytochemical and radioimmunoassay study.

The present study examines the presence of neuropeptides in the skin and plasma of patients with psoriasis using the techniques of immunocytochemistry and radioimmunoassay. Immunocytochemistry failed to demonstrate differences in the pattern of neuropeptide innervation in psoriatic lesional skin when compared to normal skin. However, radioimmunoassay of skin biopsy extracts, both substance P and vasoactive intestinal polypeptide, were significantly elevated in psoriatic lesional skin when compared with both psoriatic non-lesional and normal control skin (p less than 0.001). There was no significant difference between the plasma levels of neuropeptides in psoriatic patients compared to those of control subjects, and no significant correlation among the plasma levels of neuropeptides with the surface area of involvement with psoriasis. The finding of elevated levels of substance P and vasoactive intestinal polypeptide in lesional psoriatic skin suggests that these peptides may be involved in the pathogenesis or maintenance of the psoriatic skin lesion and the development of safe and stable antagonists of these neuropeptides may have applications in the treatment of psoriasis.

Adolescent↗
PubMed1991

Pre- and postnatal development of GABA receptors in Macaca monkey visual cortex.

GABA is a putative inhibitory neurotransmitter in adult mammalian visual cortex but also has been implicated as playing a crucial role in cortical information processing during development. In order to understand better the role of GABA during primate visual cortex development, we have examined the time course of GABAA and GABAB receptor ontogenesis in 18 Macaca nemestrina monkeys ranging from fetal day 61 (F61d) to adulthood. The GABA and benzodiazepine binding sites of the GABAA receptor were detected by 3H-muscimol (3H-MS) and 3H-flunitrazepam (3H-FZ), respectively. GABAB receptors were detected by 3H-baclofen (3H-BA). All ligands were visualized by in vitro autoradiography. Quantitative analysis of film density was done to compare laminar changes during pre- and postnatal development. Saturation binding experiments were done for MS and FZ binding sites to determine receptor number (Bmax) and affinity (Kd) at selected pre- and postnatal ages. Both MS and FZ binding sites were present at F61d-72d throughout the cortical plate and marginal zone. FZ binding sites were more dense than MS binding sites over the cortical plate at young ages and were especially dense over the marginal zone. FZ binding sites also were present in lesser amounts over the subplate and intermediate zone, but not over the subventricular zone. By F119d-126d, layer 4 could be distinguished by its higher density for both ligands. The basic adult laminar pattern was established for both MS and BZ binding sites by birth (birth = F165d-170d). After birth, MS density increases dramatically in all layers, but layer 4C remains most dense to adulthood. FZ labeling is heavy in both layers 4 and 3 at birth but after 4 weeks after birth (P4 wk) it declines somewhat in the supragranular layers so that layer 4C now predominates. Labeling in layers 5/6 virtually disappears after birth. BA binding sites were present at F126d, at which time layer 4 was slightly lighter than the remainder of striate cortex; this laminar pattern remained basically the same throughout our series to adulthood. Competitive binding of agonist and antagonists for the GABAA receptor showed that MS binding characteristics were similar at F126d and P8.5 years (yr). MS binding site Bmax was about 8% of adult values at F72d, 24% by F126d, and 56% at F152d. Bmax then rose rapidly after birth to peak at P18wk at 169% of adult values, and then declined to P1yr. A second peak of 143% was found around P3.5yr, with adult values reached by P8.5yr.(ABSTRACT TRUNCATED AT 400 WORDS)

Aging↗
PubMed1990

The complete primary structure of pancreatic polypeptide from the European common frog, Rana temporaria.

Using an antiserum directed against the highly-conserved C-terminal hexapeptide amide of mammalian pancreatic polypeptide (PP), numerous immunoreactive endocrine cells were identified within the pancreas of the European common frog, R. temporaria. An acidified ethanolic extract of pancreatic tissue (0.859 g, n = 35) contained 26.2 nmol equivalents/g of tissue. Gel permeation chromatography of the extract resolved a single peak of immunoreactivity co-eluting with synthetic bovine PP standard. Reverse phase HPLC of this material resolved a single peak of immunoreactivity which was purified to homogeneity following chromatography on a semipreparative C-18 column and an analytical C-8 column. Plasma desorption mass spectrometry (PDMS) of the purified peptide resolved a single component with a molecular mass of 4240.9 Da. Direct gas phase sequencing established the sequence of the first 26 residues. Following incubation of the peptide with endopeptidase Asp-N and direct application of the digest to the sequencer, the entire primary structure of the peptide was established as: APSEPHHPGDQATQDQLAQYYSDLYQYITFVTRPRF. The derived molecular mass of this peptide, incorporating a C-terminal amide, was 4240.6 Da which is entirely consistent with that obtained by PDMS.

Amino Acid Sequence↗
PubMed1990

The effects of mammillary body and combined amygdalar-fornix lesions on tests of delayed non-matching-to-sample in the rat.

A series of experiments compared the effects of mammillary body lesions with those of combined damage to the amygdala and fornix on 2 tests of working memory, both of which used the delayed non-matching-to-sample rule. This comparison was based on evidence of the involvement of these regions in anterograde amnesic syndromes. The mammillary body lesions had no effect on the acquisition or subsequent performance of a non-spatial recognition task and had only a mild effect on the acquisition of a spatial forced-alternation task. Although the animals with combined amygdalar plus fornix lesions were able to master the non-spatial recognition task they were impaired when the levels of proactive interference were increased. The same animals were also severely impaired on the forced-choice alternation task. The overall pattern of results is seen as mirroring those found in primates and points to an underlying similarity in the mnemonic roles of these limbic regions.

Amygdala↗
PubMed1990

Distribution and partial characterisation of immunoreactivity to the putative C-terminus of rat pancreastatin.

The presumptive C-terminal nonapeptide of rat pancreastatin was synthesised based upon the sequence of rat chromogranin A (CGA) analogous to that of porcine pancreastatin as contained within porcine CGA. Antisera were produced which were used to determine the qualitative and quantitative distribution of pancreastatin-like immunoreactivity in rat tissues by immunocytochemistry and radioimmunoassay respectively. Pancreastatin-like immunoreactivity was most abundant in pituitary, adrenal, gastric corpus and thyroid with considerably lower levels detected in the remainder of the gastroentero-pancreatic system and brain. Immunoreactivity was localised exclusively in endocrine cells and the relative abundance of immunoreactive cells paralleled the levels obtained radioimmunometrically. Chromatographic characterisation of pancreastatin-like immunoreactivity revealed molecular heterogeneity. Immunoreactive peptides of similar size to synthetic rat pancreastatin were present in gastrointestinal tissues and thyroid. These data indicate a tissue specific processing of CGA in the rat.

Animals↗
PubMed1990

Effect of cimetidine and ranitidine on the hepatic and renal elimination of nicotine in humans.

In a randomized, double-blind, cross-over experiment, 6 healthy consenting male subjects were administered cimetidine 600 mg or ranitidine 300 mg or placebo p.o. q12h x 2 days. Nicotine bitartrate was administered i.v. on day 2 (1 microgram/kg/min) x 30 min. After cimetidine mean nicotine total and metabolic clearances were decreased by 30% and 27% while after ranitidine the clearances were decreased by 10% and 7% respectively. Since smokers regulate their smoke intake based in large part on their nicotine blood levels these results suggest that the diminished nicotine total clearance in the presence of cimetidine could be important in assisting smoking reduction or cessation.

Adult↗
PubMed1990

Immunoreactivity to the pancreatic polypeptide family in the nervous system of the adult human blood fluke, Schistosoma mansoni.

The presence and distribution of neuropeptides belonging to the pancreatic polypeptide family have been demonstrated by an indirect immunofluorescence technique in the nervous systems of adult male and female Schistosoma mansoni. Seven antisera of differing regional specificity to pancreatic polypeptide (PP), peptide YY (PYY) and neuropeptide Y (NPY) were employed on both whole-mount and cryostat-sectioned material. Positive immunoreactivity (IR) was obtained with all antisera except an N-terminally-directed antiserum to NPY. In the CNS, immunoreactivity was restricted to cell bodies and nerve fibres in the anterior ganglia, central commissure and dorsal and ventral nerve cords of both sexes, whereas, in the PNS, positive-IR was present in the plexuses innervating the subtegumental musculature and the oral and ventral suckers. Intense immunoreactivity was observed in a plexus of nerve fibres and cell bodies in the lining of the gynaecophoric canal and in fine nerve fibres innervating the dorsal tubercles of the male. In contrast, in the female, strong immunoreactivity was evident in nerve plexuses innervating the lining of the ovovitelline duct and in the wall of the ootype, but most notably in a cluster of cells in the region of Mehlis' gland. Results suggest that molecules with C-terminal homology to the PP-family are present in S. mansoni. These peptides would appear to be important regulatory molecules in the parasite's nervous system and may play a role in the control of egg production.

Animals↗