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Biomedical subjects

R C Pearson

Publications and source records attributed to R C Pearson.

At least 91 records · Page 5Linked to original sources
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

The cholinergic nuclei of the basal forebrain of the rat: normal structure, development and experimentally induced degeneration.

The normal morphology and distribution of the cholinergic neurones of the basal forebrain of the rat have been studied qualitatively and quantitatively after staining immunohistochemically with a monoclonal antibody to choline acetyl transferase (ChAT). This was done in order to provide an adequate control for the changes found in these cells on both sides of the brain in the experimental investigation of the reaction of the cells to damage of their axons. The cholinergic cells form a more or less continuous anteroposterior band, but they can be subdivided into distinct nuclear groups on the basis of the size and form of the cell bodies and dendrites, their position and arrangement. these nuclei conform closely to previous descriptions of Nissl-stained material: the medial septal nucleus, the vertical and horizontal nuclei of the diagonal band and the basal nucleus. Quantitative measurements of the cross-sectional areas of the cells in the different nuclei confirmed the conclusions drawn from the qualitative examination. Measurements of the ChAT cells at different ages showed that in all nuclei they are significantly larger in size in infancy than in the adult, and they shrink to the mature size by 46 days. The cells in the various cholinergic nuclei show distinctly different reactions to damage of their terminal axonal fields. After removal of a large part of the neocortex by removal of the overlying pia-arachnoid mater the cells in the basal nucleus in the operated hemisphere underwent retrograde cellular degeneration, being swollen and paler-staining up to 14 days, and thereafter shrinking by 20-30% (as compared with those in the brains of age- and sex-matched littermate controls). The degree of shrinkage was appreciably greater when the animals were operated upon at the neonate stage. No cell loss was found, qualitatively or quantitatively, in the basal nucleus. After removal of the hippocampus there is marked loss of cholinergic neurones in the medial septal nucleus and in the vertical nucleus of the diagonal band, and with severe shrinkage of the remaining cells. Removal of the olfactory bulb results in only slight shrinkage of the cells, and no cell loss, in the horizontal nucleus of the diagonal band.(ABSTRACT TRUNCATED AT 400 WORDS)

Age Factors↗
PubMed1987

The cholinergic nuclei of the basal forebrain of the rat: hypertrophy following contralateral cortical damage or section of the corpus callosum.

After damage of the neocortex of one hemisphere by removal of the pia-arachnoid mater, the cholinergic cells of the basal nucleus of the unoperated hemisphere show a marked increase in their cross-sectional areas. This hypertrophy reaches a maximum of 25% by 3 weeks after operation and persists indefinitely. The cell bodies appear normal in shape, are often paler-staining and the hypertrophy includes the proximal dendrites. The hypertrophy is confined to the part of the basal nucleus corresponding to that which shows shrinkage on the operated side. The enlargement is greatest in animals operated upon on the first day after birth (+31%), is less in adult animals (mean +22%) but occurs at all ages up to 496 days, the oldest animal used. After unilateral removal of the hippocampus or section of the fimbria there is hypertrophy of the cholinergic neurones of the contralateral medial septal nucleus (+24%) and vertical nucleus of the diagonal band (+18%). Removal of the olfactory bulb on one side had no apparent effect upon the cholinergic neurones in the contralateral horizontal nucleus of the diagonal band. Damage of the neocortex by exitotoxic amino acids did not result in hypertrophy of the cholinergic cells of the contralateral basal nucleus despite marked shrinkage of the neurones in the basal nucleus on the operated side. After section of the corpus callosum the neurones throughout the basal nucleus of both sides are significantly larger than in the normal animal; the hypertrophy has occurred by 20 days after operation and persists indefinitely.(ABSTRACT TRUNCATED AT 250 WORDS)

Aging↗
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↗
PubMed1987

Anterograde vs. retrograde degeneration of the nucleus basalis medialis in Alzheimer's disease.

The evidence that degeneration in the basal forebrain cholinergic nuclei in Alzheimer's disease is a secondary phenomenon is reviewed. Experimental retrograde degeneration in these nuclei shares some common features with the degeneration actually observed in the disease, and can occur without direct damage to the cholinergic axons within the cortex. The neuroanatomical distribution of the pathological changes typical of Alzheimer's disease in the neocortex suggests a progression of the disease process, from the medial temporal cortex and amygdala out into the parieto-temporal association areas. Neurochemical evidence also points to the early and severe involvement of the amygdala in the disease. The close reciprocal relationship between the amygdala and the basal nucleus may underly the degeneration seen in the basal nucleus in Alzheimer's disease.

Alzheimer Disease↗
PubMed1986

Parenterally administered GM1 ganglioside prevents retrograde degeneration of cholinergic cells of the rat basal forebrain.

The effect of daily intraperitoneal injections of GM1 ganglioside on retrograde degeneration in the basal forebrain has been examined, using a monoclonal antibody directed against choline acetyltransferase to identify the cholinergic neurones. Rats underwent extensive damage of the cerebral cortex and underlying hippocampus. From the day of operation on, they received daily injections of ganglioside. After a survival of 30 days, the animals were killed and the cholinergic cells of the basal forebrain were examined. These were compared with material treated in the same way from animals who had received the injections of ganglioside but no lesion, animals who had been operated upon but without the ganglioside treatment, and normal animals. Intraperitoneal ganglioside administration markedly reduces the retrograde death of the cholinergic neurones of the medial septal nucleus and abolishes the shrinkage of the remaining neurones following hippocampal damage.

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

Hypertrophy of motor neurons in the oculomotor nucleus of the rat following removal of the contralateral extraocular muscles.

Motor neurons of the oculomotor nucleus of the rat were identified immunohistochemically using a monoclonal antibody against choline acetyltransferase (ChAT). The number and size of the cell bodies were examined following removal of the extraocular muscles on one side. 35 days postoperatively, motor neurons of the oculomotor nucleus ipsilateral to the muscle removal are undiminished in number and are of normal size when compared with littermate control animals. Cholinergic cells in the contralateral nucleus are significantly larger than normal (+23%). This hypertrophy appears to persist at least until 300 days after operation, the longest survival time examined.

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

Retrograde changes in the nucleus basalis of the rat, caused by cortical damage, are prevented by exogenous ganglioside GM1.

In rats with extensive unilateral cortical damage, retrograde effects upon the cholinergic cells of the basal nucleus were observed. Cells of the basal nucleus stained immunocytochemically for choline acetyltransferase were shrunken and choline acetyltransferase enzymatic activity in that region was reduced. Both these effects could be prevented by the administration of the ganglioside GM1.

Alzheimer Disease↗
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↗
PubMed1986

The cortex of the primary auditory area in Alzheimer's disease.

The cortex of the superior temporal gyrus has been examined in two brains with Alzheimer's disease. Numerous neurofibrillary tangles and neuritic plaques that are characteristic of the disease, were present in area 38 in the anterior part of the gyrus and in area 22 more posteriorly but the primary auditory cortex, area 41, was virtually unaffected by these pathological changes. This relatively minor involvement of the primary auditory cortex, like that of the primary somatic and visual areas, again emphasises the uniqueness of the olfactory system in being severely degenerate. The findings are considered to support the suggestion that the distribution of the pathological changes in Alzheimer's disease has an anatomical basis due to spread of the disease process along certain well-defined sets of cortical fibre connections.

Alzheimer Disease↗
PubMed1986

Vaccines and principles of immunization.

This article discusses the production of the various classes of vaccines and compares the advantages and disadvantages of each. Adjuvants, combination vaccines, heterologous viral vaccines, and vaccination failure are discussed briefly. Reported adverse reactions to vaccination are described at length. Essential vaccination for several exotic species is given.

Animals↗
PubMed1985

Degeneration of cholinergic neurons in the basal nucleus following kainic or N-methyl-D-aspartic acid application to the cerebral cortex in the rat.

The effect on cholinergic neurons in the basal nucleus of exposing the cortex to excitotoxic amino acids was examined in the rat. Kainic or N-methyl-D-aspartic acid were applied extradurally over the cerebral cortex of one side. This resulted in a severe depletion in the numbers of neurons in the underlying cortex. The immunohistochemically identified cholinergic neurons of the ipsilateral basal nucleus showed a significant shrinkage, -31% of their mean cell area, which was comparable with the retrograde degeneration seen following direct mechanical damage of the cortex. These findings suggest that cholinergic neurons of the basal nucleus can undergo transneuronal retrograde degeneration.

Animals↗