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Biomedical subjects

J W Neal

Publications and source records attributed to J W Neal.

At least 55 records · Page 3Linked to original sources
PubMed1991

Lesions of the Cerebral Cortex and Caudate-Putamen Enhance GABA Function in the Rat Superior Colliculus.

Unilateral lesions of the rat frontal cortex were made either alone or in combination with the caudate-putamen in order to examine (a) their morphological influence on the substantia nigra and (b) their neurochemical influence on GABA function in the superior colliculus. One to two months following the combined lesion, neuronal somata in the ipsilateral pars reticulata of the substantia nigra were clearly hypertrophied (+ 30%). Morphological changes in the substantia nigra were not evident contralaterally or in animals bearing only cortical lesions. One to two months following cortex-only lesions, no significant alterations in tectal GABA concentration were observed. However, the combined lesion induced elevations of GABA within both the medial and lateral sectors of the intermediate and deep layers of the superior colliculus. This effect was restricted to the ipsilateral side and was most pronounced in lateral sectors. The vast majority of GABA released from superfused control tectal slices by a depolarizing stimulus (35 mM KCl) was calcium-dependent. Such evoked GABA release from ipsilateral tectal slices was significantly reduced (- 25%) by unilateral lesions of the substantia nigra, a structure that is known to provide GABA-containing inputs to the tectum. In contrast, cortical lesions alone significantly enhanced the evoked tectal GABA release (+ 66%), although their influence was again confined to the ipsilateral side. Combined lesions of the cerebral cortex and caudate-putamen significantly enhanced the evoked GABA release from tectal slices in both hemispheres but the changes were most marked ipsilaterally (+ 147%). It is suggested that the hypertrophy of GABA-containing nigrotectal somata seen after removal of corticostriatal, corticotectal and in particular GABA-containing striatonigral fibres may reflect concomitant increases in GABA synthesis within and/or sprouting of nigrotectal terminals.

Journal Article↗
PubMed1990

The connections of area PG, 7a, with cortex in the parietal, occipital and temporal lobes of the monkey.

The cortico-cortical connections of area PG, 7a, in the parietal, occipital and temporal lobes have been studied after injections of HRP in this area and in certain of the areas connected with it. After such injections in PG there are labelled cells in architectonic areas OA and PE (visual area PO), the cingulate and retrosplenial areas situated medial to PG; posteriorly labelled cells are present in OA, visual areas MST, MT, V2, V3, V4 and in the walls and floor of the lower part of the superior temporal sulcus. Injections in PE and V4 show that these connections are reciprocal. Small injections in PG result in cell labelling in different parts of the areas connected to PG, suggesting that the connections are well organized and that there may be an ordered representation of the visual field in PG. In the lower wall of the lower part of the superior temporal sulcus there is overlap of the two visual pathways in the cortex, that to the temporal lobe with that to the parietal lobe; and in a restricted part of this sulcus there is convergence and overlap of the sequences of cortico-cortical connections related to the visual, somatic and auditory sensory systems. There may be certain common principles in the sequences of cortical connections to the parietal and temporal lobes from the primary visual and somatic sensory areas; in both there are well organized hierarchical and parallel pathways, and both are related to the superior temporal sulcus and to the cingulate cortex.

Animals↗
PubMed1990

The ipsilateral cortico-cortical connections of area 7b, PF, in the parietal and temporal lobes of the monkey.

The cortico-cortical connections of area 7b (or PF) in the parietal and temporal lobes of the monkey have been studied with the method of axoplasmic transport of horseradish peroxidase (HRP). Area 7b is reciprocally and precisely connected with area 5, the second somatic sensory area (SII), the retroinsular area, the granular insular area (Ig), area 23 of the cingulate cortex and with the cortex in the walls of the superior temporal sulcus. Area 7b is not interconnected with area 7a (PG) nor with any of the prestriate visual areas. After injections of HRP into area PF the labelled cells in all these areas, except the granular insular area, are mainly in layer III and these cells are considered to be the origin of 'feed-forward' type connections; in the granular insular area most of the cell labelling is in layer V, interpreted to be the origin of 'feed-back' connections. Between SI and area PF there are two sequences of connections in parallel with each other, one through area 5 and the other through SII. In all areas the labelled cells are in clusters of 500-2000 microns width on individual sections and in bands of these widths on planar reconstructions.

Animals↗
PubMed1990

The callosal connections of area 7b, PF in the monkey.

The callosal connections of area 7b, PF, in the monkey have been studied after injections of HRP into this area in one hemisphere. On the opposite side labelled cells were present in area 7b and in certain areas that are connected with it, area 5, SII and the insular granular area. In these areas the cells are in the representations of all parts of the body except that of the distal forelimb.

Animals↗
PubMed1990

The ipsilateral corticocortical connections of area 7 with the frontal lobe in the monkey.

The corticocortical connections between area 7 and the frontal lobe have been studied in the monkey. Injections of HRP were made into area 7 of the parietal lobe or into area 46 in the walls of the principal sulcus. The two subdivisions of area 7, 7a or PG and 7b or PF, are connected with different parts of the frontal lobe, and each subdivision is connected with two distinct areas. Area 7b, PF, is connected in a well organized and somatotopic manner with the lower premotor area and with the lower part of area 46, below the fundus of the principal sulcus. Area 7a, PG, is connected with area 8a and with the upper part of area 46, above the fundus of the principal sulcus; it is suggested that the lower part of area 8a and the posterior part of area 46 are related to the central visual field, while the medial part of area 8a and the anterior part of area 46 are related to the periphery of the visual field. The corticocortical connections between area 7 and the frontal lobe are reciprocal and those passing from area 7 to the frontal lobe are 'feed-forward' and those to area 7 are 'feed-back'.

Animals↗
PubMed1990

Malakoplakia of the pancreas.

We report a case of malakoplakia arising in the pancreas of a 45-year-old woman. Clinical and histological features are described. Malakoplakia was present with chronic pancreatitis and adenocarcinoma. The aetiology of malakoplakia at this site may be due to a stromal response to carcinoma or an abnormal localised histiocytic response to infection or inflammation. This case and previous reported cases suggest that the aetiology and pathogenesis of pancreatic malakoplakia is not the same for all patients.

Adenocarcinoma↗
PubMed1989

Squamous cell carcinoma in a duplicate large intestine. A case report.

A case report of a squamous cell carcinoma arising in a closed duplication of the large intestine is presented. The aetiology of squamous cell carcinoma in this site is discussed. It is quite possible the epithelial changes described in this case are similar to those associated with squamous cell carcinoma in other anatomical sites. The unusual environment within the lumen of a closed duplication may be carcinogenic.

Carcinoma, Squamous Cell↗
PubMed1989

In vitro inhibition of prostaglandin H synthase by compounds from the exocrine secretions of lace bugs.

1. Selected lace bug-derived and related compounds were shown to be in vitro inhibitors of mammalian and insect derived prostaglandin H synthase. 2. Two compounds, 2,6-dihydroxyacetophenone and 2,4,6-trihydroxyacetophenone, were significantly better inhibitors of prostaglandin synthesis than aspirin, whereas 2-nonyl-5,7-dihydroxychromone and 1-(2,6-dihydroxyphenyl) dodecan-1-one were equivalent to aspirin. 3. 2,4-Dihydroxyacetophenone was less effective in inhibiting the prostaglandin H synthase and 2-nonyl-5-hydroxychromanone showed no inhibition. 4. Three compounds, 2,6-dihydroxyacetophenone, 2,4,6-trihydroxyacetophenone and 1-(2,6-dihydroxyphenyl) dodecan-1-one were equal to aspirin in PSI inhibition with fat body preparations of the American cockroach Periplaneta americana L.

Animals↗
PubMed1988

The cortico-cortical connections within the parieto-temporal lobe of area PG,7a, in the monkey.

After injections of HRP into area PG(7a) labelled cells have been found in architectonic areas OA, PE, the cingulate and retrosplenial areas medial to area PG; posteriorly areas MST, OA (V4), V2, V3 and the cortex in the walls and floor of the superior temporal sulcus have also been labelled. Small injections placed in PG have resulted in different parts of these areas being labelled, suggesting that these cortico-cortical connections are well organized and raising the possibility of an ordered representation of the visual field in PG. It is suggested that the vertical meridian is around the boundary and the horizontal meridian passes antero-posteriorly across about the middle of its medio-lateral extent; the central part of the visual field is in the depths of the intraparietal sulcus, and the periphery is on the surface of the inferior parietal lobule and in the anterior wall of the upper part of the superior temporal sulcus. The lower visual field is medial and the upper field is lateral.

Animals↗
PubMed1988

The organization of the cortico-cortical connections between the walls of the lower part of the superior temporal sulcus and the inferior parietal lobule in the monkey.

After injections of HRP into area 7a,PG, in the monkey labelled cells have been found in the walls and floor of the lower part of the superior temporal sulcus; the part of area 7a,PG, in the posterior wall of the intraparietal sulcus is connected with the floor and posterior wall of the superior temporal sulcus, and the part of 7a,PG on the surface of the inferior parietal lobule with the floor and anterior wall. Area 7b,PF is related to a restricted part of the floor of the superior temporal sulcus.

Animals↗
PubMed1987

The cortico-cortical connections of area 7b, PF, in the parietal lobe of the monkey.

The cortico-cortical connections of area 7b (or PF) in the parietal lobe of the monkey have been studied with the method of axoplasmic transport of horseradish peroxidase or with the method of axonal terminal degeneration. Area 7b is reciprocally and precisely connected with area 5, the second somatic sensory area (SII), area 23 of the cingulate cortex, the retroinsular area (Ri), the granular insular area (Ig), and with the cortex in the walls of the superior temporal sulcus.

Animals↗
PubMed1987

Increase in immunohistochemical staining of GABAergic axons in the superior colliculus and thalamus of the rat following damage of the ipsilateral striatum and frontal cortex.

The superior colliculus and ventromedial nucleus of the thalamus have been examined in rats following damage of the frontal cortex and underlying striatum with immunohistochemical staining using an antiserum directed against gamma-aminobutyric acid (GABA). Following such lesions, at a time when the cell bodies of the neurones in the ipsilateral pars reticulata of the substantia nigra are known to be significantly enlarged, there is substantially more immunostaining of GABAergic fibres in both sites when compared with the contralateral side and with normal littermate control animals. The increase in immunoreactivity may indicate sprouting of the axons of the enlarging pars reticulata neurones or an increase in immunoreaction of existing fibres.

Animals↗
PubMed1987

Bilateral morphological changes in the substantia nigra of the rat following unilateral damage of the striatum.

The effects of damage of the striatum and globus pallidus of one side on the size of cells in the pars reticulata and pars compacta of the substantia nigra on both sides and in the contralateral globus pallidus have been examined. Cellular cross-sectional areas have been compared with those for neurons in the same nuclei in normal age and sex matched littermate control animals. One week after removal of the left striatum and globus pallidus and overlying cortex, the cells in the ipsilateral pars compacta are significantly shrunken (15%). This decrease in size gets progressively more marked with longer survival times reaching 50% 112 days after operation, the longest survival time examined. The shrinkage is accompanied by marked cell loss. Neurons in the contralateral pars compacta show an initial significant hypertrophy of their cell bodies (20%) in the first week after the operation, and later show a shrinkage of 20% at 35 days. The degree of this contralateral shrinkage gradually declines to 12% at 112 days. The changes in the pars compacta are accompanied by a significant enlargement (33%) of the cells in the pars reticulata of the substantia nigra on the side of the damage. This hypertrophy is present by 35 days after operation and persists at least until 112 days. Similar hypertrophy occurs in the ipsilateral globus pallidus in the one case where this could be examined. There are no significant changes in the contralateral pars reticulata, but there is significant enlargement (23%) of the neurons in the contralateral globus pallidus.

Animals↗
PubMed1986

Hypertrophy of cholinergic neurones of the basal nucleus in the rat following damage of the contralateral nucleus.

The effect of damage of the basal nucleus of one side on the size of immunohistochemically identified cholinergic cells in the contralateral nucleus has been studied in rats. Following stereotaxic injections of kainic acid into the nucleus of one side, the choline acetyltransferase (ChAT)-containing neurones in the contralateral basal nucleus are significantly larger (mean +19%) than those in normal animals. This hypertrophy is of comparable magnitude to that seen following damage of the contralateral cortex (mean +21%) and appears to persist indefinitely.

Animals↗
PubMed1986

The organization of the corticocortical projection of area 5 upon area 7 in the parietal lobe of the monkey.

The distribution of labelled cells and of extracellular granules in the cortex of area 5 of the parietal lobe of the monkey has been studied after injections of horseradish peroxidase into area 7. Area 5 is related only to area 7b (PF) and not to area 7a (PG). The corticocortical connections between area 5 and 7b are reciprocal and well organized so that the same representations in each area are interconnected. No corticocortical fibres pass between areas 7a (PG) and 7b (PF).

Animals↗
PubMed1986

The relationship between the auditory cortex and the claustrum in the cat.

The relationship between the primary auditory cortex and the claustrum has been re-examined in the cat with axoplasmic flow and axonal degeneration methods. Labelled cells are found in a restricted part of the claustrum after injections of HRP or HRP-WGA in the primary auditory cortex, but they are relatively few in number and are palely stained. The number of labelled cells and their depth of staining are greatest at 72 h (the longest survival time used here), and this survival period an occasional labelled cell is also present in the claustrum of the contralateral hemisphere. No labelled cells are seen after 24 h. After small lesions in the primary auditory cortex, fibre and terminal degeneration are present in the part of the claustrum where labelled cells are seen with axoplasmic flow techniques. It is concluded that there are reciprocal connections between the primary auditory cortex and the claustrum, but the rate of axoplasmic flow is unusually slow.

Animals↗