PubMed Health⌕ Search

Biomedical subjects

P C Barber

Publications and source records attributed to P C Barber.

At least 37 records · Page 2Linked to original sources
PubMed1993

11 beta-hydroxysteroid dehydrogenase and corticosteroid hormone receptors in the rat colon.

In the rat kidney 11 beta-hydroxysteroid dehydrogenase (11 beta-HSD) maintains normal in vivo specificity for mineralocorticoid receptor (MR) by converting the active steroid corticosterone to inactive 11-dehydrocorticosterone, leaving aldosterone to occupy the MR. Clinical observations support the hypothesis that 11 beta-HSD also protects the distal colonic MR from glucocorticoid excess. We have measured 11 beta-HSD mRNA and activity along the rat colon and have analyzed the distribution of 11 beta-HSD, MR, and glucocorticoid receptor (GR) mRNA within rat distal colon using in situ hybridization. Levels of 11 beta-HSD mRNA (1.7 and 3.4 kb) and activity were higher in distal vs. proximal colon, paralleling reported MR mRNA levels. Within the distal colon mucosa both 11 beta-HSD immunoreactivity and mRNA was observed in cells in the lamina propria but not in epithelial cells. MR mRNA was present in surface epithelial cells, but was also colocalized with the same 11 beta-HSD-expressing cells in the lamina propria. In contrast GR mRNA was more uniformly distributed. The localization of MR mRNA to nonepithelial cells in the lamina propria, possibly neuroendocrine cells, suggests that mineralocorticoid-regulated sodium transport across colonic epithelial cells may also involve a paracrine mechanism. As with the kidney, exposure of active mineralocorticoid to the MR in these cells in the lamina propria is dictated by 11 beta-HSD in an autocrine fashion.

11-beta-Hydroxysteroid Dehydrogenases↗
PubMed1992

Anatomical and immunohistological demonstration of the primary neural connections of the vomeronasal organ in the dog.

Macro- and microdissection methods together with conventional histology and lectin immunohistochemistry have been used to identify the course of the vomeronasal nerves and their site of termination (accessory olfactory bulb; AOB) in the dog. The AOB in this species is small and variable in size, situated on the medial surface of the main olfactory bulb, and has an anatomical structure unlike that described for other mammals. The vomeronasal nerves and their terminal glomeruli in the AOB are easily identifiable by selective immunohistochemical staining using Ulex europeus agglutinin I.

Animals↗
PubMed1992

Pharmacological comparison of the sigma recognition site labelled by [3H]haloperidol in human and rat cerebellum.

The radioligand binding characteristics of [3H]haloperidol (in the presence of spiperone, 25 nmolL-1) were investigated in rat and human cerebellar membranes. In both rat and human cerebellar membrane preparations saturation studies with [3H]haloperidol (non-specific binding defined by pentazocine, 10 mumolsL-1) demonstrated high affinity saturable specific binding to a homogenous population of binding sites (rat, Bmax 6693 +/- 1242 fmol mg-1 protein, pKD 8.33 +/- 0.08; human, Bmax 2550 +/- 437 fmol mg-1 protein, pKD 8.59 +/- 0.11; mean +/- SEM, n = 3-6). Competition studies employing a wide range of structurally diverse competing compounds displayed that the [3H]haloperidol binding site was pharmacologically similar in both preparations and comparable to sigma recognition sites previously identified in various tissues originating from different species. In addition, with reference to the potential subtypes of sigma recognition sites, the labelling of these sites by low nanomolar concentrations of [3H]haloperidol provides evidence that they belong to the sigma-1 recognition site subtype. The present findings suggest that the pharmacology of the rat and human cerebellar sigma recognition site are directly comparable and provides further supporting evidence towards the use of [3H]haloperidol radioligand binding studies in the rat to detect sigma receptor ligands with potential therapeutic activity.

Animals↗
PubMed1991

Identification of angiotensin II receptor subtypes in human brain.

The present study assessed the binding characteristics of [125I]angiotensin II to slices of human cerebellum adhered to glass slides using quantitative receptor autoradiography. Specific [125I]angiotensin II binding, defined by the inclusion of unlabelled angiotensin II (1.0 microM), was detected in the molecular layer of the cerebellum (0.09 +/- 0.02 fmol/mg tissue equivalent, mean +/- s.e.m., n = 3). The angiotensin II-2 receptor subtype selective ligand, PD123177, competed for approximately 65% of the specific binding in the molecular layer whilst the remainder of the specific binding was displaced by the angiotensin II-1 receptor subtype selective ligand, DuP753. It is concluded that angiotensin II receptor subtypes exist in human brain tissue and provide potential therapeutic sites of action.

Aged↗
PubMed1989

Ulex europeus agglutinin I binds exclusively to primary olfactory neurons in the rat nervous system.

Lectin binding histochemistry was used to investigate the distribution of binding sites for the fucose-selective lectin Ulex europeus agglutinin I in the rat nervous system. It was found that this lectin bound exclusively to a surface membrane component, probably a glycoprotein, on primary olfactory and vomeronasal sensory neurons, and to no other structure in the nervous system. A similar pattern of Ulex europeus agglutinin I binding was found in adult, immature and embryonic rats. Binding was also demonstrated on olfactory axons regenerating through a peripheral nerve graft. Three other lectins, including another fucose-selective lectin, and the N-acetyl galactosamine-binding soybean lectin failed to show similar exclusive binding. The presence of a specific surface glycoconjugate solely on olfactory neurons suggests that the molecule may play some role in development or maintenance of organization of this neuronal pathway.

Aging↗
PubMed1988

Primary lymphoma of the central nervous system: experience at Addenbrooke's Hospital, Cambridge.

A series of 22 cases of primary intercerebral lymphoma are reported. The clinical presentation and natural history were similar to high grade glioma in adults. There was a male to female ratio of 2.7:1, and a mean age at presentation of 63 years (range 47-72 years). Single masses were present in 77%, and the frontal lobe was the most frequently involved (64%). Treatment regimes included varying combinations of surgical resection and cranial irradiation. Sixteen patients have died, twelve due to recurrent or persistent intracerebral disease. The median survival was ten months. Six patients are still alive at 52, 12, 10, 9, 6 and 4 months. Failure to control the intracranial tumours was the main cause of death. Significant debulking of the tumour was the single most important prognostic factor, although a good initial response to steroids was also favourable. No patient developed spinal deposits. Even when there is a good response to radiation and prolonged survival, the quality of life may be poor: in this series only five out of 22 patients (23%) returned to a normal life. Radiation dosage and the indications for spinal treatment are discussed.

Aged↗
PubMed1988

The immunolocalization of protein gene product 9.5 using rabbit polyclonal and mouse monoclonal antibodies.

In order to assess the potential of protein gene product (PGP) 9.5 as a marker of the nervous and neuroendocrine systems, we examined its immunolocation in human, rat and guinea-pig tissues, using a rabbit polyclonal antiserum and two new mouse monoclonal antisera, I3C4 and 3IA3. Our results demonstrate immunoreactive PGP 9.5 in neurons and nerve fibres at all levels of the central and peripheral nervous system, in many neuroendocrine cells, in part of the renal tubule, in spermatogonia and Leydig cells of the testis, and in ova and in some cells of the pregnant and non-pregnant corpus luteum. In routinely processed tissues, standard immunohistochemical techniques using the polyclonal antibody demonstrated peripheral nerve fibres of all sizes with striking clarity.

Animals↗
PubMed1988

Primary intracranial Hodgkin's disease. A case report and discussion.

We report here a case in which a frontotemporal meningeal tumor was found to be an isolated, apparently primary, deposit of nodular sclerosing Hodgkin's disease in an otherwise well man. The presentation of Hodgkin's disease as a primary, solitary intracranial lesion is rare; only 13 cases have been found in the world literature. The histological appearance of the tumor in the present case fulfills all the requirements for nodular sclerosing Hodgkin's disease according to current criteria of classification; the morphologic diagnosis is supported by appropriate immunohistochemical staining of the neoplastic cells for Leu M1 and LN2 markers, with absence of staining for the common leucocyte antigen. No recurrent local or disseminated disease has been manifest in a 14-month follow-up of the patient.

Brain Neoplasms↗
PubMed1987

Glial fibrillary acidic protein (GFAP)-like immunoreactivity in normal and transected rat olfactory nerve.

Normal and transected rat olfactory nerves were stained immunohistochemically using a monoclonal antibody previously shown to selectively detect GFAP-like immunoreactivity in central astrocytes but not in peripheral Schwann cells. Low levels of "central" type GFAP were found in the olfactory nerves, presumably in ensheathing cells. The levels of GFAP increased dramatically after nerve transection. A population of strongly GFAP-positive cells was detected at the junction between the olfactory epithelium and initial part of the nerves, of possible relevance to the regenerative abilities of this pathway.

Animals↗
PubMed1985

Early stages of Purkinje cell maturation demonstrated by Thy-1 immunohistochemistry on postnatal rat cerebellum.

The cell surface glycoprotein, Thy-1, is present on Purkinje cells at birth, so allowing Thy-1 immunohistochemistry to demonstrate the final stage of migration and the transition to dendritic growth of these cells. In the most caudal lobule of the cerebellar cortex of the newborn rat, migrating Purkinje cells are found. These have a prominent process (up to 50 micron long) from which fine filopodia project, presumably sensing the environment in front of the cell. These cells are orientated tangentially, at right angles to the radial orientation they assume for dendritic growth. Strong Thy-1 labelling is found not only on their surface, but also on a cytoplasmic cap above the presumed leading pole of the nucleus. More rostrally in the cerebellar cortex, Purkinje cells arrive up to 3 days before birth and are quiescent until the postnatal development of their dendritic tree. At birth and during early postnatal periods a rounded cell is found with little cytoplasm; Thy-1 staining labels its surface and the fine processes which emanate from it. Such cells coexist with other Thy-1-positive Purkinje cells with more developed surface orientated processes. Even as early as the day of birth these fine processes cross the molecular layer and contact the lower level of the external granule layer. Orientated dendritic growth appears to occur by a selective thickening of these processes and a massive apical protrusion of intensely Thy-1-positive cytoplasm. The whole of the Purkinje cell surface membrane exhibits high levels of Thy-1 throughout dendritic growth and synaptogenesis, and cytoplasmic antigen is prominent during the period of greatest growth. Thy-1 is also found on the neurons of the deep cerebellar nuclei, and is seen transiently on Golgi interneurons. High levels of the antigen are present on blood vessels and choroid plexus at birth but are lost from these structures over the first 2 postnatal weeks.

Animals↗
PubMed1985

Late emergence of Thy-1 on climbing fibres demonstrates a gradient of maturation from the fissures to the folial convexities in developing rat cerebellum.

In the third week of postnatal life, Thy-1 staining of Purkinje cells starts to decrease, first in the depths of the fissures and then progressively, over the next 10 weeks, up the walls of the fissures to the convexities of the folia. This is accompanied by a far more striking appearance of high levels of Thy-1 on a network of fibres whose distribution strongly suggests they are climbing fibres. They acquire the antigen in the same topographical gradient of maturation, and at the same time, as Purkinje cells lose it. That these are climbing fibres was confirmed by destroying the inferior olive with 3-acetylpyridine, which also eliminated the intense Thy-1 staining in the cerebellum. At a stage (18 days) when only some climbing fibres in the molecular layer are seen to be Thy-1-positive, only a proportion of inferior olivary neurons are Thy-1-positive with intense antigen labelling over the Nissl substance. The possibility that Thy-1 also appears on mossy fibres, and at relatively low levels on parallel fibres, is discussed.

Afferent Pathways↗
PubMed1983

The distribution of Thy-1 antigen in the P.N.S. of the adult rat.

The distribution of the cell surface glycoprotein Thy-1 in the P.N.S. of adult rats was examined using immunohistochemical and experimental techniques. In the hypoglossal nerve the pattern of Thy-1 labelling suggested the antigen was on the plasma membrane of all axons, not only in their major myelinated course but also on their fine terminal branches and at the motor end plate itself. Similarly in other peripheral nerves examined [phrenic and vagus nerves, dorsal and ventral roots, and both the preganglionic and postganglionic trunks of the superior cervical ganglion (SCG) and the submandibular ganglion] Thy-1 was always associated with axons, but the resolution obtained with immunohistochemical techniques was not in itself sufficient to exclude the possibility that the antigen was on the surface of the ensheathing Schwann cell where it apposed the axons. However, in the hypoglossal nerve the antigen was found to accumulate proximal to a ligation of the nerve, suggesting it was made by the neurons and transported down the nerve by axoplasmic flow. This impression was supported by examining neuronal cell bodies in the SCG, dorsal root ganglia and submandibular ganglion, all of which contain readily detectable cytoplasmic Thy-1. In the SCG this cytoplasmic antigen was shown to include the pool of newly synthesized Thy-1. It was increased by treatment of the ganglion with colchicine, and decreased by cycloheximide. Conversely, treatment of hypoglossal nerve trunk with colchicine did not lead to the appearance of the antigen around the non-neuronal perikarya. It is therefore concluded that in those parts of the adult rat P.N.S. examined, Thy-1 is made by neurons and occurs generally on the plasma membrane of axons.

Animals↗
PubMed1983

Fixation of Thy-1 in nervous tissue for immunohistochemistry: a quantitative assessment of the effect of different fixation conditions upon retention of antigenicity and the cross-linking of Thy-1.

It has proved difficult to obtain good immunohistochemical localization of cell surface antigens in nerve for a number of reasons, prominent among which are problems of fixing this class of molecule without destroying their antigenicity. In the course of developing a fixation procedure suitable for one such antigen. Thy-1, we have quantitatively assessed the effect of different fixation parameters upon the retention of Thy-1 antigenicity and upon the extent of cross-linking of the antigen in the tissue. The former was measured using radioimmunoassays adapted for membrane antigens in fixed tissue, the latter by measuring the proportion of antigen rendered insoluble to the detergent, sodium deoxycholate, and by examining the size of the antigen on sodium dodecyl sulfate--polyacrylamide gels. These approaches demonstrated that minor modifications of the standard vascular perfusion fixation of brain, using both glutaraldehyde and paraformaldehyde, were sufficient to fix the Thy-1 molecule, and at the same time substantially spare its antigenicity. In this study we measured Thy-1 using both a conventional rabbit antiserum and a mouse monoclonal antibody to the Thy-1.1 antigenic determinant. The multiple antigenic determinants recognized by the rabbit antibodies were cumulatively more resistant to fixation than the single antigenic determinant recognized by the monoclonal antibody.

Animals↗
PubMed1982

Adjacent laminar terminations of two centrifugal afferent pathways to the accessory olfactory bulb in the mouse.

Anterograde and retrograde axonal tracing methods have been combined with transection of the stria terminalis to investigate the centrifugal afferent connections of the accessory olfactory bulb in the mouse. Injection of tritiated proline into the postero-medial cortical amygdaloid nucleus (C3) gives rise to anterograde autoradiographic labelling of a pathway terminating in the internal granular layer of the accessory olfactory bulb (AOB). Transection of the ipsilateral stria terminalis completely abolishes labelling of this pathway. Injections further rostral, in the bed nucleus of the accessory olfactory tract (bnAOT) and medial amygdaloid nucleus (M), give rise to labelling of a second ipsilateral afferent pathway to the AOB which terminates in the internal plexiform layer (IPL) and is unaffected by strial transection. Injections of wheat germ lectin-HRP conjugate into the AOB confirm that it receives afferents from the ipsilateral bnAOT, M and C3, and from a few cells in the contralateral C3. Transection of the ipsilateral stria terminalis prevents retrograde labelling of any cells in the ipsilateral C3, but does not affect labelling of cells in M or bnAOT (or contralateral C3). The conjugate is also transported anterogradely in this system, labelling the efferent projections of the AOB to bnAOT, M and C3. It is concluded that the AOB receives at least two sets of ipsilateral afferents: one set from C3, via the stria terminalis, terminating in the internal granular layer, and a second set from M and/or bnAOT terminating in the IPL and probably running in the accessory olfactory tract.

Amygdala↗
PubMed1982

Astrocyte cultures from adult rat brain. Derivation, characterization and neurotrophic properties of pure astroglial cells from corpus callosum.

It has not as yet been routinely possible to derive primary cultures of glial cells from adult rat brain tissue even when adopting strategies that have proven successful with perinatal tissue. We now report that in response to a surgical lesion and a period of postoperative 'priming' in vivo, proliferating cultures of astroglial cells can be derived from the normally quiescent glia of the corpus callosum region of the adult rat brain. In such cultures the predominance of astroglia and the virtual absence of oligodendroglia and neurons has been established by the use of a variety of cell-type specific antisera. Fibroblasts, the only other cell type identified, when not numerous could be successfully eliminated by treatment of the cultures with anti-Thy-1 antibodies and guinea pig complement. Pure astroglial cells from adult brain have been sub-cultured and maintained for up to 4 months in vitro, providing suitable quantities of cells for studies on the trophic interaction between glia and neurons. In long-term culture the adult astrocytes maintain a flattened undifferentiated morphology but readily assume a stellate shape with long branching processes upon the addition of a crude homogenate from bovine pituitary.

Animals↗
PubMed1982

Regeneration of olfactory sensory axons into transplanted segments of peripheral nerve.

Isolated segments of cervical sympathetic trunk were transplanted onto the olfactory mucosa and bulb in adult rats, and olfactory nerve fascicles were sectioned in the region of the transplant. Olfactory axons, presumably arising from newly-formed sensory neurons, were observed to grow into the transplanted segments of peripheral nerve and were ensheathed by Schwann cells of the transplant. The axons were ensheathed as large bundles containing many axons in direct contact, an arrangement characteristic of the normal olfactory nerves, and not of the normal sympathetic trunk. However, single Schwann cell 'units' were each surrounded by basal lamina, an arrangement typical of the sympathetic trunk, not of olfactory nerves. The results indicate that olfactory axons, like other peripheral axons, are capable of directing some aspects of the manner in which they are ensheathed by Schwann cells.

Animals↗