Biomedical subjects

A E Bishop

Publications and source records attributed to A E Bishop.

At least 19 recordsLinked to original sources

PubMed1995

Secretoneurin: a new peptide in the human enteric nervous system.

Secretoneurin is a functional neuropeptide derived from secretogranin II (chromogranin C). This proprotein is processed to varying degrees in neuroendocrine tissues. In the present study we established by gel filtration high performance liquid chromatography that in human intestinal wall and mucosa an antiserum against secretoneurin detects as the major immunoreactive moiety the free peptide secretoneurin. In the mucosa some larger immunoreactive peptides were also present, however, a significant amount of the intact proprotein secretogranin II could not be detected. By immunohistochemistry we studied the distribution of secretoneurin within the gut. Antibodies to protein gene product 9.5 and chromogranin A were used to identify all neurons and endocrine cells, respectively, whilst those to the peptides substance P, CGRP and somatostatin were used for the further characterization of individual secretoneurin-positive structures. Secretoneurin immunoreactivity was found in nerve fibres in all layers of the gut wall. In both myenteric and submucous plexuses, nerve fibres and the majority of ganglion cells were secretoneurin-immunoreactive. In the mucosa, some secretoneurin-positive nerve processes ran parallel to the basal membrane of epithelial cells, occasionally invading the epithelial layer. Secretoneurin immunoreactivity was found in endocrine cells, mostly D cells, in the following regions in descending order of density: stomach/duodenum; rectum; colon; ileum. Thus, secretoneurin is a new major peptide within the human enteric neuroendocrine system. Its presence in abundant myenteric ganglion cells may imply a role in the modulation of gastrointestinal motility. The chemotactic properties of secretoneurin and its possible localization in sensory fibres suggest that this peptide may be involved in the genesis of intestinal inflammation.

Adult↗

PubMed1995

Increased expression of cell adhesion molecule P-selectin in active inflammatory bowel disease.

The pathogenic changes of inflammatory bowel disease (IBD) depend on migration of circulating leucocytes into intestinal tissues. Although leucocyte rolling and tenuous adhesion are probably regulated by inducible selectins on vascular endothelia, little is known about the expression of these molecules in Crohn's disease and ulcerative colitis. Using immunohistochemistry on surgically resected specimens, this study investigated endothelial P-selectin (CD62, granular membrane protein-140) in frozen sections of histologically uninvolved tissues adjacent to inflammation (Crohn's disease = 10; ulcerative colitis = 10), from highly inflamed areas (Crohn's disease = 20; ulcerative colitis = 13), and from normal bowel (n = 20). By light microscopy, two forms of P-selectin immunoreactivity were detected that apparently corresponded ultrastructurally to stored and released distributions. Compared with the normal gut, there was a 3.7-fold increase of P-selectin immunoreactivity on veins (p < 0.0001), venules (p < 0.0001), and capillaries (p < 0.05) in the highly inflamed gut, without differences between Crohn's disease and ulcerative colitis. In the uninvolved gut, P-selectin expression was similar to that seen in normal controls, except for a focal increase of P-selectin in the vicinity of small lymphocyte aggregates. The dramatic upregulation of P-selectin in the inflamed tissue and its potential role in leucocyte trafficking support the concept of P-selectin blocking therapy for the control of active IBD.

Adolescent↗

PubMed1995

Surgical cure of hypertension in a patient with brainstem capillary haemangioblastoma containing neuropeptide Y.

We describe a 29-year-old woman with persistent arterial hypertension which resolved following complete excision of a capillary haemangioblastoma from within the spinal cord at the cervico-medullary junction. Immunohistochemical staining was positive for neuropeptide Y in capillary walls and nerves in the tumour. This raises the possibility of an association between neuropeptide Y and the central control of blood pressure in man.

Adult↗

PubMed1994

A computer-assisted stereological quantification program: OpenStereo.

At present, the stereological assessment of histological sections is made possible by the use of manual counting techniques which estimate measurement parameters. These methods are tedious, time-consuming, and subject to operator error. This paper describes a UNIX-based computer program, OpenStereo, which was developed to facilitate the quantitative investigation of innervation and vascularity from histological sections. We designed OpenStereo to reduce operator error and increase the efficiency of stereological point counting for volume estimation and intercept counting for surface area analysis. The program was written in the C language for the Sun Workstation and uses the XView graphics user interface. Digital images, obtained by a variety of modalities, may be processed using stereological point counting, interceptions, planimetry, or thresholding techniques. The program displays selected images in a random fashion for analysis or processing and records the number of manually selected points or interceptions. Delineation of the reference space provides the computer with the data necessary to calculate volume or surface densities. The efficiency of OpenStereo was demonstrated by performing a pilot study on the quantification of innervation in the normal human colon and ileum. This stereological package benefits from the features of the X-windowing environment and has proved to be suitable for what has hitherto been a tedious and time-consuming task.

Adult↗

PubMed1994

Pancreatic changes elicited by chronic administration of excess L-arginine.

Male rats were injected daily ip (350 mg/100 g body weight) with L-arginine from 1 to 4 weeks. Weekly changes were assessed by glucose tolerance, pancreatic insulin, histology, immunohistochemistry, ultrastructure, and quantification of insulin mRNA by in situ hybridization. Following Week 1, light microscopy revealed areas of focal acinar cell degeneration and incipient disaggregation of exocrine cytoarchitecture. Ultrastructural changes revealed initial attenuation in endoplasmic reticulum and condensation and clumping of nuclear chromatin. Some mitochondria appeared swollen and the plasma membrane showed areas of focal disintegration. Islets appeared normal, although pancreatic insulin levels were lower than controls as was the quantified signal for insulin mRNA. At the end of Week 2, acinar necrosis was evident throughout most pancreatic lobules. Increasing numbers of acinar cells underwent progressive degeneration with further loss of plasma membrane integrity, the appearance of autophagic vacuoles, increased cytoplasmic debris, and mitochondrial disruption. At Week 4, only isolated single acinar cells remained within a fibrous connective tissue matrix contiguous with ducts, blood vessels, intrapancreatic nerves, and islets. Immunohistochemistry of islets and nerves revealed normal endocrine and neural components. Although nonfasted, arginine-treated rats were normoglycemic and no further significant changes in pancreatic insulin and mRNA were found between Weeks 2 and 4, some impairment of glucose tolerance was present throughout the 4-week period. Data support the hypothesis that excess arginine selectively destroys acinar cells. It is suggested that necrosis arises from attenuation in nucleoprotein synthesis which may result from amino acid imbalance and/or toxicity. Excess arginine-treated animals may serve as a model for the study of acute and chronic pancreatitis.

Animals↗

PubMed1994

Nitric oxide, and not vasoactive intestinal peptide, as the main neurotransmitter of vagally induced relaxation of the guinea pig stomach.

1. Nitric oxide synthase (NOS) was localized in the guinea pig stomach by immunocytochemistry. In vitro experiments were carried out on the isolated stomach of the guinea pig to study any possible links between nitric oxide (NO) and vasoactive intestinal peptide (VIP) in mediating relaxations induced by vagal stimulation. 2. NOS was localized to nerve cell bodies and nerve fibre varicosities of the myenteric plexus in wholemounts of the longitudinal muscle-myenteric plexus of the stomach fundus. The NOS-positive cells had a Dogiel type I morphology characteristic of motor neurones. 3. The cross-sections of the stomach wall showed NOS-positive neurones mainly in the myenteric plexus ganglia and NOS-positive nerve fibre varicosities in the circular muscle layer. 4. Relaxations induced by vagal stimulation were almost completely prevented by L-NAME with an IC50 value of 5.5 x 10(-6) M. This inhibition was reversed by L-arginine (2 mM). 5. VIP (100 nM) induced reproducible relaxations of the stomach. These were unaffected by tetrodotoxin (2 microM) or N omega-nitro-L-arginine methyl ester (L-NAME, 100 microM). 6. Desensitization to the relaxant effect of VIP partially reduced relaxations induced by vagal stimulation, glyceryl trinitrate or sodium nitroprusside but not noradrenaline. 7. These results show that NO has a neuronal origin in the guinea pig stomach, and support NO, and not VIP, as the major neurotransmitter of vagally induced gastric relaxation in the guinea pig.

Amino Acid Oxidoreductases↗

PubMed1993

Localisation of nitric oxide synthase within non-adrenergic, non-cholinergic nerves in the mouse anococcygeus.

Immunocytochemical staining of whole mount preparations of the mouse anococcygeus muscle, using antibodies to rat brain nitric oxide synthase (NOS), revealed a dense network of NOS-immunoreactive nerve fibres running through the tissue. These fibres were resistant to the sympathetic neurotoxin 6-hydroxydopamine and are therefore likely to be the non-adrenergic nerves which mediate relaxation of this smooth muscle. Further, NOS-immunoreactive fibres were absent following denervation by cold-storage (4 degrees C; 72 h), which has been shown to abolish non-adrenergic, non-cholinergic (NANC) relaxations. The results provide strong support for the hypothesis that the L-arginine:NO pathway is responsible for the generation of the NANC transmitter in the anococcygeus.

Amino Acid Oxidoreductases↗

PubMed1993

Immunocytochemistry for neuronal markers shows deficiencies in conventional histology in the treatment of Hirschsprung's disease.

Despite technically satisfactory operations, at least 20% of children with Hirschsprung's disease have an unsatisfactory postoperative result. A possible explanation for their symptoms is the retention of ganglionic intestine which has demonstrable abnormalities of the enteric nervous system. The distribution of intestinal neural proteins and peptides in resected colons from patients with Hirschsprung's disease (n = 10) was compared with that in normal controls (n = 5). Immunocytochemistry was performed using antisera against general markers of the enteric nervous system (PGP 9.5, NSE, NFILs, and S-100 protein) and colonic neuropeptides (VIP, GAL, SP, NPY, CGRP, and Met-ENK). The distribution and density of peptide-containing nerve fibers varied greatly from one patient to another and no consistent pattern of neural disturbances could be discerned in aganglionic colon. At the proximal limit of resection, abnormalities of enteric innervation were detected in 8 of 10 studied specimens. Although ganglion cells staining positively for general neuronal markers were present in all cases, normal populations of neural cell bodies immunoreactive for neuropeptides could be found in only 2 specimens. Enlarged submucosal nerve trunks found in the most proximal area of most specimens, displayed immunoreactivity for general nerve markers and VIP, GAL, NPY, and CGRP. The widely practised conventional histopathological assessment of the proximal limit of colonic neural abnormalities may be inadequate.

Calcitonin Gene-Related Peptide↗

PubMed1992

Effect of Helicobacter pylori on gastric somatostatin in duodenal ulcer disease.

Infection of the gastric antrum by Helicobacter pylori is associated with recurrent duodenal ulcer disease but the mechanism of ulcerogenesis is unclear. Since pathways inhibiting gastric secretion are defective in patients with duodenal ulcers, we investigated whether H pylori interferes with the normal gastric inhibition that is mediated by somatostatin. We studied 28 patients with active duodenal ulcers in whom H pylori was eradicated successfully. In 18 patients, we measured the density of antral somatostatin-immunoreactive cells and in a further 10 subjects, the amount of somatostatin mRNA before and after eradication of H pylori was determined. After eradication, the median density of somatostatin-immunoreactive cells increased significantly from 9 (range 3-47) to 19 (6-57) cells per mm muscularis mucosa (p = 0.025). The median somatostatin mRNA/rRNA ratio increased from 50 (25-160) to 95 (40-180) (p = 0.01). The number of gastrin cells and quantity of gastrin mRNA did not change significantly. Our results suggest that in duodenal ulcer disease, gastric secretory function is disinhibited through the suppression of mucosal somatostatin.

Adult↗

PubMed1992

Autoradiographic localization of endothelin-1 binding sites in human colonic cancer tissue.

Endothelin-1, a potent vasoconstrictor, has been reported to stimulate mitogenesis in various types of normal and neoplastic cells and to be involved in neurotransmission. Recently, many human cancer cell lines, including those from the human colon, have been shown to produce endothelin. In this study, the occurrence of endothelin-1 binding sites was investigated in human colonic cancer tissues using in vitro autoradiography. Specific [125I]endothelin-1 binding sites were identified over tumour vessels and stromal tissues surrounding cancer cell nests. The distribution was heterogeneous, and dense silver grains were localized, especially over clusters of fibroblasts adjacent to the cancer cell nests. Endothelin binding was minimal in the cancer cells, as in the normal crypt epithelium. Quantitative analysis of the autoradiographs demonstrated high affinity (Kd = 0.50 +/- 0.06 nM; mean +/- SEM) binding sites, with a maximum binding capacity (Bmax) of 40 +/- 3.2 amol/mm2 in the cancer tissues. Our results provide evidence that specific endothelin-1 binding sites are expressed in the stromal tissues including tumour vessels, fibroblasts, and nerve fibres. Endothelin-1 may play a modulatory role in blood supply, mitogenesis, and neurotransmission in a paracrine fashion through the stromal components in human colonic cancers.

Adenocarcinoma↗

PubMed1992

Immunological detection of nitric oxide synthase(s) in human tissues using heterologous antibodies suggesting different isoforms.

Nitric oxide (NO) is generated from L-arginine by NO synthases. Localization of the brain enzyme has been carried out in the rat; however, despite data suggesting that NO is a major regulator of vascular and neural functions in man, there is no information about the localization of NO synthase in human tissues. Rabbit antisera to NO synthase purified from rat brain (antisera A and B) were raised, tested by Western blotting, affinity purification and enzyme immunoprecipitation assay, and used to investigate the distribution of the enzyme in a variety of human tissues by immunohistochemistry. Antisera to two synthetic peptides from cloned neural NO synthase were used to aid specificity testing. Anti-sera A and B reacted with a approximately 160-kDa protein in Western blots of human brain extracts, gave immunostaining of nerves, and precipitated enzyme activity from rat brain homogenates. Antiserum B to NO synthase also reacted with proteins of M(r) between 125 and 140 kDa in extracts of well-vascularised tissues, and immunostained vascular endothelium; the neural and vascular immunoreactivity persisted after affinity purification of antiserum B with the approximately 160 kDa protein. Endothelial staining with antiserum B was seen in respiratory tract, liver, skin and umbilicus; syncytial trophoblasts stained in the placenta. Neural staining with antiserum A and B was seen in the myenteric and submucous plexus, and in nerve fibres in smooth muscle of the gut and in many areas of the central nervous system, particularly cortex, hippocampus, hypothalamus, cerebellum, brain stem and spinal cord.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Oxidoreductases↗

PubMed1992

The ontogeny and distribution of neuropeptides in the human fetal and infant esophagus.

The innervation and neuropeptide expression of fetal and infant human esophagus were studied. Esophageal samples (n = 30) from 8 weeks' gestation to 28 months of age were immunostained using antisera to general and specific neuronal antigens, and the results were quantified using computer-assisted image analysis. Nerve protein (protein gene peptide 9.5 and synaptophysin) and glial cell protein (S100) immunoreactivities were present by 8 weeks' gestation in primitive cell bodies and fibers in the outer layers of the esophagus. Immunoreactivity for peptides was first detected in fibers at 11 weeks' gestation in myenteric plexus and at 13 weeks' gestation in muscle. Peptide-immunoreactive cell bodies were not seen until 13-15 weeks. A pattern of immunoreactivity for neuropeptides comparable with that seen in mature neonates and infants was present by 22 weeks of gestational age. The percentage area of protein gene peptide 9.5-immunoreactive and vasoactive intestinal peptide-immunoreactive nerve fibers increased from low levels to 3.68% and 0.27%, respectively, at 13 weeks and peaked at 18 weeks (10.50% and 4.74%). These findings provide a foundation for future research into the contribution of neuropeptides to pediatric esophageal dysmotility.

Aging↗

PubMed1992

Vasoactive intestinal polypeptide gene expression in the developing human gastrointestinal tract.

Expression of vasoactive intestinal polypeptide has been shown, by immunocytochemistry and biochemical assay, to follow the craniocaudal neural colonization of the mammalian gut. The aim of this study was to use in situ hybridization to see if it could provide more information on vasoactive intestinal polypeptide gene expression in the developing human gut. Immunocytochemistry of vasoactive intestinal polypeptide and, to visualize the total innervation, protein gene product 9.5 was also applied. By 8 weeks of gestation, protein gene product 9.5-immunoreactive neurons had colonized the gut lengthwise (17% of intestinal muscle area) but not transversely. Vasoactive intestinal polypeptide immunoreactivity was first detected at 9 weeks of gestation in a few nerve fibers of the upper gut, the origin of which could not be determined. Vasoactive intestinal polypeptide-immunoreactive ganglion cells were not seen until 18 weeks of gestation, whereas in situ hybridization showed messenger RNA in ganglion cells of the upper gut at 9 weeks. An adultlike pattern of peptide gene products (e.g., 2.5% and 3.1% of intestinal mucosal or muscle area, respectively) was detected by 20 weeks' gestation. The finding that the vasoactive intestinal polypeptide gene is expressed first in the upper human gut is consistent with craniocaudal neuronal colonization and maturation.

Adult↗

PubMed1992

Distribution and origin of extrinsic nerve fibers containing calcitonin gene-related peptide, substance P and galanin in the rat upper rectum.

The distributions of nerve fibers containing calcitonin gene-related peptide (CGRP), substance P (SP) and galanin (GAL) were examined in the rat rectum of mutants rats, aganglionic rats (AGRs), which completely lack the intramural nerve cells in the large intestine, and of their normal littermates. The origin of extrinsic peptide-containing nerve fibers was examined using retrograde tracing combined with immunohistochemistry in normal rats. In the rectum of normal rats, CGRP-, SP- and GAL-immunoreactive varicose fibers were observed throughout all layers of the rectal wall, and immunoreactive nerve cells were present in the enteric ganglia of colchicine-treated rats. In the aganglionic rectum of AGR, a rich supply of CGRP-immunoreactive fibers was observed in the mucosa, around the blood vessels, and in the submucous and intermuscular spaces. SP- and GAL-immunoreactive fibers in the aganglionic rectum showed a similar distribution to CGRP-immunoreactive fibers but were less dense. These results suggest that most of CGRP-positive fibers in the rectum are extrinsic whereas a large part of SP- or GAL-positive fibers are intrinsic. Fluoro-gold injected into the upper rectum of normal rat labelled nerve cells (less than 10% of total ganglion cells) in the lumbar (L1 and L2) and lumbosacral (L6 and S1) dorsal root ganglia. More than half of nerve cells in the dorsal root ganglia (L6 and S1) projecting to the rectum were immunoreactive for CGRP, and less than 10% were immunoreactive for SP or GAL. Comparison of serial sections of the dorsal root ganglion revealed that about half of the CGRP-immunoreactive cells were also positive for SP or GAL. These results indicate that SP- or GAL-positive neurons projecting to the rectum are scarce in the dorsal root ganglia. The present investigation suggests that CGRP-containing nerves are visceral afferents forming a major component of the sensory innervation of the rat rectum, and SP- and GAL-containing nerves which share their extrinsic origins appear to form a lesser proportion of the sensory innervation.

Animals↗

PubMed1992

Localisation of endothelin like immunoreactivity in adult and developing human gut.

The distribution of immunoreactivity for the potent vasoconstrictor endothelin-1 was studied in adult and developing human gut using antisera to endothelin-1 (1-21) and the C terminus of big endothelin-1. The coexistence of these peptides with other neuropeptides was investigated using comparative immunocytochemistry. Endothelin-1 like immunoreactivity was detected in extracts of adult (range 20-60 fmol/g wet weight) and fetal (33 fmol/g) gastrointestinal tract and was shown by chromatography to be the predominant isoform of endothelin present in both. It was localised by immunocytochemistry to ganglion cells in the submucous and myenteric plexuses and to scattered nerves, whereas big endothelin-1 like immunoreactivity was found in the submucous plexus only. Colocalisation studies showed immunoreactivity for both endothelin-1 and vasoactive intestinal peptide in the same ganglion cells of the submucous plexus. Although endothelin-1 immunoreactivity was not detected by immunocytochemistry in the fetal human gut until the 32nd week of gestation, big endothelin-1 was found as early as 11 weeks in the developing neural structures and epithelial cells. The latter were shown to be endocrine cells by their immunoreactivity for chromogranin. Our results indicate that endothelin is a neuropeptide found in adult human gut which shows transient expression in endocrine cells during development.

Adult↗

PubMed1992

Quantitative study of the development and maturation of human oesophageal innervation.

By 8 wk gestation, the human fetal oesophagus is identifiable as a hollow epithelium-lined tube with primitive nerve and muscle precursors present. From 8-16 wk gestation, the muscle layers and innervation mature until fetal swallowing commences at 16 wk. This study examines quantitatively the development and maturation of nerve fibres and cell bodies within the oesophagus using histochemistry. Oesophageal samples (n = 35) from 8 wk gestation to 28 months of age and adults (n = 3) were immunostained using antisera for the general nerve marker, protein gene product (PGP 9.5), the glial tissue marker S100, and the synaptic vesicle protein synaptophysin (p38). Histochemical staining for NADH diaphorase enzyme activity was also used to identify neurons. Computer-assisted image analysis of the muscularis externa permitted detailed quantification of cell size, nerve density and myenteric (plexus) fraction. At 8 wk gestation, PGP and synaptophysin were present in immature neurons throughout the cytoplasm, but from 10 wk synaptophysin was localised solely at nerve synapses. S100 immunoreactivity was also detected from 8 wk gestation onwards and was confined to glial tissue. Nerve cell size increased with maturation from 6 microns at 8 wk gestation to 20 microns at term and 21 microns at 28 months. The numbers of cells, nerve density (% area occupied by nerves throughout section) and myenteric fraction (% area occupied by ganglion cells and nerve fibres within the myenteric plexus) all peaked at 16-20 wk gestation and, whereas the number and density then fell towards adult levels, the myenteric fraction fell during the late second trimester and became constant from 30 wk gestation.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗

PubMed1991

Localization of endothelinlike immunoreactivity and endothelin binding sites in human colon.

The potent vasoconstrictor endothelin was originally isolated from vascular endothelial cells but has since been found in several other tissues. The aim of this study was to establish whether endothelinlike immunoreactivity occurs in human enteric nerves and to identify endothelin binding sites using immunocytochemical and in vitro autoradiographic techniques. Endothelinlike immunoreactivity was localized to nerve bundles throughout the colon and to most of the ganglion cells of the two major plexuses, many of which costored vasoactive intestinal polypeptide. High-affinity (dissociation constant = 0.35 +/- 0.014 nmol/L; mean +/- SEM) binding sites for endothelin 1, with an apparent binding capacity of 92 +/- 6.3 amol/mm2 (mean +/- SEM), were demonstrated in the myenteric plexus, with less dense binding being found in the submucous plexus, mucosa, muscle layers, and blood vessel walls. Competition data suggested two populations of binding sites, both showing high affinities for endothelins 1 and 2, vasoactive intestinal constrictor, and sarafatoxin b but differentiated by their affinity for endothelin 3 and sarafatoxin c. This study provides evidence that endothelin is a neuropeptide in the human intestine with binding sites on neural plexuses and mucosa, suggesting a role in the modulation of intestinal motility and secretion.

Adult↗

PubMed1991

Localization of endothelin-1 and its binding sites to the nervous system of the human colon.

Endothelin-1 (ET-1) has been reported to possess a wide variety of biological activities, including neurotransmission. Our aim was to demonstrate ET-like immunoreactivity (ET-LI) and its binding sites in human enteric nervous system using immunohistochemistry and in vitro autoradiography. ET-LI was displayed in nerve bundles and most of the ganglion cells in both myenteric and submucous plexuses, many of which costored VIP. [125I]ET-1 binding sites were identified, especially to plexuses, mucosa, and blood vessels. High-affinity (Kd = 0.35 +/- 0.014 nM; mean +/- SEM) binding sites, with a maximum binding capacity (Bmax) of 92 +/- 6.3 amol/mm2, were demonstrated in the myenteric plexus. This study provides evidence that ET-1 is a neuropeptide in the human colon with binding sites on neural plexuses and mucosa, indicating a possible role in the modulation of motility and secretion in the human intestine.

Autoradiography↗