Biomedical subjects

A E Bishop

Publications and source records attributed to A E Bishop.

At least 19 recordsLinked to original sources

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↗

PubMed1990

Gastrinomas in the duodenums of patients with multiple endocrine neoplasia type 1 and the Zollinger-Ellison syndrome.

In patients with multiple endocrine neoplasia type 1 (MEN-1), gastrinomas are common and thought to occur predominantly in the pancreas. We describe eight patients with MEN-1 and hypergastrinemia (seven with the Zollinger-Ellison syndrome) in whom we searched for neuroendocrine tumors in the pancreas and duodenum. Tumors were found in the proximal duodenum in all eight patients: solitary tumors (diameter, 6 to 20 mm) in three patients and multiple microtumors (diameter, 2 to 6 mm) in the other five. Paraduodenal lymph-node metastases were detected in four patients. Immunocytochemical analysis revealed the presence of gastrin in all the duodenal tumors and in their lymph-node metastases. In contrast, no immunoreactivity for gastrin was present in the endocrine tumors found in the seven pancreatic specimens available for study, except for one tumor with scattered gastrin-positive cells. In four of the six patients whose duodenal gastrinomas were removed, serum gastrin levels returned to normal; in the other two patients gastrin concentrations decreased toward normal. We conclude that in patients with MEN-1 and the Zollinger-Ellison syndrome, gastrinomas occur in the duodenum, but the tumors may be so small that they escape detection.

Adult↗

PubMed1990

Expression of Lewis(a), Lewis(b), and sialated Lewis(a) antigens in early and advanced human gastric cancers.

An immunohistochemical analysis of the expression of Lewis(a), Lewis(b), and sialated Lewis(a) blood group antigens was performed on specimens of human non-involved stomach (n = 91), early gastric cancers (n = 41), and advanced gastric cancers (n = 50). In non-involved stomach, Lewis(a) and Lewis(b) were detected mainly in surface epithelium, although sialated Lewis(a) was scarcely expressed. These blood group-related antigens were rarely observed in deep glands. In gastric cancers, Lewis(a) showed a tendency to be expressed in well or moderately differentiated carcinomas, and this was observed to be more marked in advanced tumors. There was no obvious difference in positive ratios of Lewis(b) between degrees of differentiation of the cancers. Sialated Lewis(a) was not detected in early cancers, and its frequent expression in well- or moderately differentiated, advanced carcinomas suggested an association with both cancer differentiation and progression. These results indicate that knowledge of the expression of blood group antigens may help interpret the antigenic alterations occurring in the course of carcinogenesis, differentiation, and progression of gastric cancers.

Adenocarcinoma↗

PubMed1990

Neuromedin U-like immunoreactivity in the thyroid gland of the rat.

Neuromedin U is a novel neuropeptide found to have a widespread distribution extending throughout the mammalian central nervous system, gastrointestinal tract and the endocrine cells of the pituitary gland. In order to investigate the possibility that neuromedin U-like immunoreactivity is also present in the thyroid gland of the adult rat we have examined its localisation and molecular nature by radioimmunoassay, immunocytochemistry and chromatographic analysis. The neuromedin U content of the whole thyroid gland was found to be 331 +/- 67 fmol/gland (mean +/- SEM), and this value significantly decreased (163 +/- 17 fmol/gland) as a result of 14 days of treatment with the anti-thyroid agent methimazole (10 mg/rat/day. Thyrotoxicosis induced by exogenous T4 (10 micrograms/rat/day) failed to alter the thyroid content of this peptide. Immunostaining studies localised neuromedin U to a minor population of parafollicular C-cells in untreated animals. Complementary chromatographic studies revealed a single molecular form of neuromedin U-like immunoreactivity in thyroid tissue extracts which was indistinguishable from synthetic rat neuromedin U standard.

Animals↗

PubMed1990

An in vitro study of the projections of enteric vasoactive intestinal polypeptide-immunoreactive neurons in the human colon.

The anatomical basis of the peptidergic neural control of the human colon is largely unknown. In this study, in vitro retrograde tracing methods have been used on fresh human colon to determine the projection pathways of the enteric nerves and, in particular, those containing vasoactive intestinal polypeptide, one of the most abundant and potent of the gut neuropeptides. Two components of the submucous plexus were identified, the inner one projecting to the lamina propria, and the outer to the circular muscle. The lengths of projections within the submucous plexus were up to 5-14 mm in all directions. Myenteric ganglion cells projected to both longitudinal and circular muscles, for distances of up to only 5 mm. The subpopulation of nerves containing vasoactive intestinal polypeptide arose mainly from the submucous plexus and projected up to 6.5 mm anally, 5 mm orally, and 14 mm within the submucous layer to the mucosa or circular muscle. These findings provide entirely new data on the neuroanatomy of the human colon and may help in the understanding of the neural control of colonic secretion and motility.

Adult↗

PubMed1990

Gastric enterochromaffin-like (ECL) cells in hypergastrinaemic duodenal ulcer disease.

Patients with hypergastrinaemic duodenal ulcer disease were studied to determine whether chronic moderate hypergastrinaemia produces hyperplasia of gastric enterochromaffin-like cells in man. Eight patients had peak postprandial plasma gastrin concentrations greater than 200 pmol/l, which is the 92nd percentile for patients with duodenal ulcer disease in this laboratory. The control group was eight patients with duodenal ulcers whose peak postprandial gastrin concentrations were less than 200 pmol/l. Basal and peak postprandial plasma gastrin concentrations were 107 (37) and 306 (66) pmol/l (mean (SEM] respectively in the hypergastrinaemic patients compared with 26 (4) and 137 (14) pmol/l respectively in the controls. There was no significant difference in the density of gastrin enterochromaffin-like cells between the two groups. The number of enterochromaffin-like cells per high power field was 53 (8) in the hypergastrinaemic patients compared with 50 (8) in the controls. We conclude that chronic moderate hypergastrinaemia does not produce hyperplasia of enterochromaffin-like cells in man. Our hypergastrinaemic group had plasma gastrin concentrations similar to, or greater than those reported during treatment with drugs such as omeprazole and histamine H2 receptor blockers.

Adult↗

PubMed1989

Expression of tachykinins by ileal and lung carcinoid tumors assessed by combined in situ hybridization, immunocytochemistry, and radioimmunoassay.

Mid-gut carcinoid tumors have been shown to produce substance P, a tachykinin. A recent addition to this family of peptides is neurokinin A which is cleaved from the same precursor as substance P; beta-pre-pro-tachykinin. The authors have examined mid-gut and pulmonary carcinoid tumors for the presence of the two tachykinins, using immunocytochemical study and radioimmunoassay, and have applied the techniques of in situ hybridization and Northern blot analysis to investigate the expression of mRNA for beta-pre-pro-tachykinin. All gut tumors (n = 8) and three of the six lung tumors examined were found by immunocytochemical study to contain both tachykinins or neurokinin A alone. Chromatographic analysis of tumor extracts suggests that this peptide is being detected as a separate molecule and/or as the C-terminal portion of a larger, uncleaved form. Three of the cases positive for tachykinins showed no detectable serotonin immunoreactivity. Strong hybridization signals for beta-pre-pro-tachykinin mRNA were seen in all but one of the cases studied which contained tachykinin immunoreactivity. Intact mRNA and positive hybridization was found by Northern blot analysis in two mid-gut tumors. Concentrations of tachykinins were found by radioimmunoassay to be higher in mid-gut tumors (substance P 27.2 +/- 19.7 pmol/g; neurokinin A 31.8 +/- 24.2 pmol/g; mean +/- SEM, n = 5) than in lung cases (substance P mean 0.8, range 0.5-1.0 pmol/g; neurokinin A mean 11.0, range 10.0-12.0 pmol/g; n = 3). These results show that mid-gut and pulmonary carcinoid tumors produce tachykinins, which are detected, in some cases, where no serotonin immunoreactivity can be found, possibly because of a high rate of amine secretion. Screening for tachykinins may prove to be a useful diagnostic adjunct for these tumors.

Blotting, Northern↗

PubMed1989

Detection of human probombesin mRNA in neuroendocrine (small cell) carcinoma of the lung. In situ hybridization with cRNA probe.

The production of human bombesin (gastrin-releasing peptide), a peptide with mitogenic action, is a recognized feature of neuroendocrine (small cell) carcinoma of the lung. However, immunostaining of bombesin is not always possible in these tumors, probably because of poor storage mechanisms or rapid release of hormone. Molecular biological analysis of the gene encoding human bombesin has revealed the DNA sequence of human pro-bombesin. We have used in situ hybridization to study the expression of the human bombesin gene at the cellular level in small cell carcinoma of the lung. Probombesin cDNA was subcloned in pSP64 vector, linearized with Bam HI and transcribed in the presence of phosphorus 32(32P)-cytosine triphosphate (CTP) and SP6 polymerase. The cRNA probe was applied to tissue sections (from six cases of small cell carcinoma of the lung, freshly fixed in 4% paraformaldehyde), cell culture preparations (two different cell lines of small cell carcinoma), and cytologic specimens (smears of cells from three different cases of small cell carcinoma). Hybridization of probombesin mRNA was detected in tumor cells in all samples. Specificity of the signal was determined by control experiments, including the use of a probe which has a sequence identical to probombesin mRNA. Our results provide evidence for the expression of the bombesin gene in small cell carcinoma of the lung at a cellular level and show that probombesin mRNA is highly expressed in these tumors.

Bombesin↗

PubMed1989

Enterochromaffin-like cell populations in human fundic mucosa: quantitative studies of their variations with age, sex, and plasma gastrin levels.

The human gastric fundal mucosa contains a variety of endocrine cells, the most numerous of which are the so-called enterochromaffin-like (ECL) cells. We have studied the variations with age and sex of the ECL cell populations, utilizing an assessment based on multiple endoscopic biopsies from four groups of subjects. Plasma gastrin levels were also determined in these subjects. In males, endocrine cell densities declined with age but the ECL cell numbers in females opposed this trend. ECL cell counts showed no appreciable differences between young and old females. In older females, there was a high rate of gastritis and increased levels of circulating gastrin. Concentrations in older females (29.6 +/- 8.7 pmol/l) were higher than in both younger (less than 45 years) males (5.3 +/- 1.1 pmol/l) and older (greater than 55 years) males (6.3 +/- 0.6 pmol/l) (P less than 0.05). The plasma gastrin level was also higher in older females than in young females (13.1 +/- 4.5 pmol/l), although this difference failed to reach statistical significance. In conclusion, clinically silent gastritis, raised gastrin levels, and maintenance or rise of ECL cells numbers, in opposition to a general decrease in endocrine cells with age, appear to be features of women of more than 55 years of age. The variations in ECL cell populations reported here should be taken into account when evaluating possible pathological alterations of the stomach.

Adult↗