PubMed Health⌕ Search

Biomedical subjects

L Probert

Publications and source records attributed to L Probert.

48 records · Page 3Linked to original sources
PubMed1983

Tissue localization and relative distribution of regulatory peptides in separated layers from the human bowel.

The localization and distribution of regulatory peptides was studied in separated epithelium, lamina propria, submucosa, and external muscular layer from 16 specimens of human bowel. Immunoreactive enteroglucagon, gastric inhibitory polypeptide, and neurotensin were almost confined to the epithelial fraction (97.5 +/- 2.2%, 97.5 +/- 4.2%, and 99.3 +/- 1.1% of their respective total content, mean +/- SEM) and were only localized in endocrine cells. Vasoactive intestinal polypeptide-, substance P-, and bombesinlike peptides were virtually restricted to the nonepithelial layers (99.6 +/- 0.2%, 99.6 +/- 0.2%, and 100%) and were demonstrated exclusively in nerves. A particularly rich vasoactive intestinal polypeptide- and substance P-immunoreactive nerve supply was seen in the nonepithelial mucosa, which contained the highest concentrations of these peptides, while bombesin was mainly recovered from the external muscle (87.7 +/- 2.7%). Somatostatin, measured with an antiserum highly specific for somatostatin-14, was found throughout the wall, mainly in the epithelium (39.9 +/- 5.2%) and lamina propria (29.5 +/- 5.9%), but could be immunostained only in endocrine cells.

Aged↗
PubMed1983

Ultrastructural localization of four different neuropeptides within separate populations of p-type nerves in the guinea pig colon.

The ultrastructural localization of four neuropeptides, substance P, vasoactive intestinal polypeptide, Met-enkephalin, and somatostatin, in the guinea pig colon was investigated using electron immunocytochemistry. Each peptide was localized to the large granular vesicles in separate subpopulations of p-type nerves. These nerves could often be distinguished by the size and appearance of their immunostained granular vesicle cores. Thus, vasoactive intestinal polypeptide- and somatostatin-immunoreactive vesicles contained cores that were significantly larger (p less than 0.005) than those of substance P- or Met-enkephalin-positive vesicles. In addition, vasoactive intestinal polypeptide-immunoreactive vesicle cores were less well defined and more variable in shape than those of somatostatin-positive vesicles. Substance P- and Met-enkephalin-immunoreactive vesicle cores, however, were very similar in size (p greater than 0.05) and appearance and could only be differentiated using immunocytochemistry. This study demonstrates that the four neuropeptides under investigation are present within separate, often ultrastructurally distinct, neuronal systems in the gut. The distribution of these nerves within the colon is also described.

Animals↗
PubMed1982

Mapping, quantitative distribution and origin of substance p- and VIP-containing nerves in the uvea of guinea pig eye.

VIP- and substance P-like immunoreactivities were found in considerable concentrations (VIP: 17.3 +/- 4.8 pmol/g, mean +/- SEM; substance P:11.1 +/- 1.8 pmol/g) in the uveal portion of the guinea pig eye. Immunocytochemistry localised these two regulatory peptides to nerve fibres found principally in a plexus in the iris (substance P) and in an extensive network surrounding the blood vessels of the choroid (VIP). A remarkable anatomical demarcation of the two types of peptide-containing nerves was established by the staining of substance P-containing nerves, which stops at the level of the ciliary body. This uveal area is known to be involved in the ocular responses to nociceptive stimuli. At the ultrastructural level, immunoreactivity for both peptides was localised to distinct subpopulations of p-type nerves, distinguishable by the size of their large dense-cored vesicles. Those immunoreactive for VIP were significantly larger (p less than 0.0005) than those immunoreactive for substance P (95 +/- 7 nm and 82 +/- 9 nm respectively; mean +/- SD). Interruption of the trigeminal pathway produced a remarkable decrease of substance P immunoreactivity in the anterior portion of the uvea (9.1 +/- 1.5 pmol/g, mean +/- SEM, control; 5.3 +/- 1.3 pmol/g, denervated), but not of VIP immunoreactivity in the choroid. Following colchicine treatment, VIP-immunoreactive neuronal cell bodies were localised in the choroid. The separate anatomical localisations and distributions of the two uveal peptides appear to be related to their different origins and functional roles in the response of the eye to noxious stimuli.

Acetylcholinesterase↗
PubMed1982

Peptidergic nerves.

In recent years the autonomic nervous system has been shown to consist of nerves containing a number of different neurotransmitter substances; a system far more complex than was originally thought. It has been demonstrated that a large part of the autonomic nervous system contains peptides, and that, in the gut, these nerves form a major complex that infiltrates the entire length and breadth of the tract. The detailed study of this peptidergic system has been facilitated by the development of specialised immunocytochemical methods, which have yielded information on the distribution and morphology of the various types of nerve. Thus, the distribution of these nerves can often be seen to parallel what is known about the actions of individual peptides. The majority of peptidergic nerves are intrinsic to the gut, forming, with the other intrinsic nerves, what appears to be a largely autonomous unit. This enteric system can be visualised as a "minibrain", under the general influence of the central nervous system but able to function, to a certain extent, by itself. The consequences of a breakdown in the normal functioning of this system can be seen in a number of gut diseases.

Animals↗
PubMed1981

Regulatory peptides in endocrine cells and autonomic nerves: electron immunocytochemistry.

Advances in immunocytochemistry, particularly at the electron microscope level, have enabled us to establish further details of the ultrastructural appearance of endocrine cells and autonomic nerves of the gastrointestinal tract. Its contribution can be summarised as follows: a)validation of previously recognised endocrine cell types. b) Recognition of sub-groups within endocrine cells and autonomic nerve cell types previously included within one single type (e.g. D1 cells and p-type autonomic nerves). c) Discrimination of molecular forms now known to be stored in morphologically distinguishable secretory granules or parts thereof (e.g. pro-glucagon and glucagon in A cells and gut and antral gastrin-producing cells). Advances in the techniques and the accurate quantification of the end products will enable us to recognise changes in gastrointestinal tract diseases in man.

Animals↗
PubMed1979

Calcitonin-like cells in the pharynx of the ascidian Styela clava.

A small group of granulated endocrine cells have been described in the endostylar region of the pharynx in Styela. These cells are argyrophilic and exhibit calcitonin-like immunofluorescence. Tests with antisera to other peptides all proved negative. Cells from animals exposed to elevated calcium levels showed a degree od degranulation. The possibility that these cells may represent ancestral ultimobranchial "C" cells is discussed.

Animals↗
PubMedDate not supplied

Immunogold staining procedure for the localisation of regulatory peptides.

The use of protein A- and IgG-conjugated colloidal gold staining methods for the immuno-localisation of peptide hormones and neurotransmitters at light- and electron microscope level are described and discussed. Bright-field and dark-ground illumination modes have been used to visualise the gold-labelled antigenic sites at the light microscope level. Immunogold staining procedures at the ultrastructural level using region-specific antisera have been adopted to localise specific molecular forms of peptides including gastrin (G17 and G34), glucagon and pro-glucagon, insulin and pro-insulin, in normal tissue and in tumours of the gastroenteropancreatic system. Similar methods have been used to demonstrate the heterogeneity of p-type nerves in the enteric nervous system. Vasoactive intestinal polypeptide (VIP) has been localised to granular sites (mean +/- S.D. granule diameter = 98 +/- 19 nm) in nerve terminals of the enteric plexuses and in tumour cells of diarrhoeogenic VIP-producing neoplasias (mean +/- S.D. granule diameter = 126 +/- 37 nm) using immunogold procedures applied to ultraviolet-cured ultrathin sections. Co-localisation of amines and peptides in carotid body type I cells and in chromaffin cells of normal adrenal medulla and phaeochromocytomas has also been demonstrated. Advantages of the immunogold procedures over alternative immunocytochemical techniques are discussed.

Animals↗
PubMedDate not supplied

Transgenic and knockout analyses of the role of TNF in immune regulation and disease pathogenesis.

Transgenic mutagenesis in whole animals has become without doubt the most rewarding approach to analyse gene structure, expression, and function. In the TNF field, much of what we now question about TNF/TNF receptor function is based, to a large extent, on what we have already learned by overexpressing these molecules in transgenic mice or by ablating their expression in knockout systems. In addition, a clearer view of the involvement of these molecules in disease pathogenesis has emerged, and useful models for human disease have been generated. In this overview, we summarise our experience with TNF transgenic and knockout systems, and highlight advances made in our understanding of the role played by TNF and its receptors in immune regulation and in the pathogenesis of infectious, inflammatory, and autoimmune disease.

Adjuvants, Immunologic↗