Tissue viability. Toe-nail avulsion.
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Bandages, Hydrocolloid↗
Biomedical subjects
G Bruce
Publications and source records attributed to G Bruce.
Enhancement of thymic recovery after cyclosporine by recombinant human growth hormone and insulin-like growth factor I.
Correlation of thymic changes with the development of CsA-associated syngeneic graft-versus-host disease (sGVHD) suggested that the development of tolerance depends on the prompt regeneration of the thymus after stopping CsA. Accordingly, we have tested recombinant human growth hormone (rhGH) and recombinant human insulin-like growth factor I (rhIGF-1) to determine if they accelerate reconstitution of the rat thymus after CsA-induced involution. After 14 days of CsA, the thymus has marked medullary involution but normally recovers fully in 6 weeks. In this study, LEW rats were injected with vehicle, rhGH, or rhIGF-1 for 21 days after stopping CsA and were examined. The vehicle-treated rats showed partial recovery with respect to Hassall's corpuscles, class II antigen expression, medullary size, medullary dendritic cells (DC), and T cell maturation. The mature thymocytes were predominantly CD8+ T cells. Both rhGH and rhIGF-1 induced significant thymic enlargement compared with the vehicle-treated rats. They also both significantly enhanced regeneration with respect to Hassall's corpuscles. The mature thymocyte population had significantly greater CD4+ cells. In addition, rhIGF-1 induced a significant improvement in the medullary size and medullary DC. While the medullae of a normal thymus are in intimate contact with cortical class II antigen, after CsA the cortex adjacent to the medulla is primarily class II antigen negative. RhGH significantly increased the class II antigen in the deep cortex while rhIGF-1 demonstrated a trend toward greater expression in this region (P = 0.06). We conclude that rhGH and rhIGF-1 accelerate thymic regeneration post-CsA. Further studies are now indicated to establish the potential for these factors to enhance the development of antigen-specific tolerance.
Animals↗
The phosphorylation of choline acetyltransferase.
Human placental Choline Acetyltransferase (ChAT) has been shown to be phosphorylated in vitro by kinases present in rat brain. Phosphorylation occurs at a single site with the exclusive phosphoamino acid being serine. ChAT phosphorylation was shown to be calcium, and not cyclic nucleotide, dependent and was inhibited by inhibitors of calcium/calmodulin protein kinases including anti-calmodulin anti-sera. ChAT phosphorylation was stimulated by calmodulin (9 fold) and, to a lesser extent, by phosphatidylserine (4 fold). These results indicate the involvement of a calcium/calmodulin and possibly also a calcium/phospholipid kinase. This finding was confirmed by demonstrating ChAT phosphorylation using both purified multifunctional calcium/calmodulin protein kinase (CaMK) and calcium/phospholipid protein kinase C (PKC) from rat brain. A stoichiometric incorporation of 0.9 mol phosphate/mol ChAT was achieved by CaMK. Phosphorylated ChAT could be isolated from freshly prepared rat brain synaptosomes. The results obtained with this model system support the hypothesis that in vivo a fraction of ChAT exists phosphorylated.
Amino Acids↗
An atlas of the regional and laminar distribution of choline acetyltransferase immunoreactivity in rat cerebral cortex.
The distribution of cholinergic fibers in rat cortex was investigated using choline acetyl-transferase immunohistochemistry. Previous studies have either shown differences in distribution, but have been limited to selected areas, or have shown no discernable differences between different cortical areas. In our study, we examined all areas of rat cortex and found that there are striking interareal and interlaminar differences in cholinergic fiber distribution. We have found that certain functionally similar cortical areas (e.g. sensory, motor, etc.) have similar patterns of cholinergic innervation and we have designated 13 general patterns of cortical cholinergic innervation. We have also compared, on an area-by-area basis, the pattern of acetylcholinesterase reactivity to that of choline acetyltransferase immunoreactivity, since acetylcholinesterase has been used for many years as a putative cholinergic marker. We found that in most cortical areas, the distribution of acetylcholinesterase-positive fibers paralleled that of choline acetyltransferase-immunoreactive fibers; however, there were some striking differences, notably primary somatosensory (the "barrelfield"), retrosplenial and cingulate cortices. In some areas, a revised concept of rat cortical organization, using cytoarchitectonics, was required. The results of this study provide a comprehensive microscopic analysis of cholinergic fiber innervation of the rat cortex. These results are discussed in relation to previous anatomical, physiological and pharmacological studies of cortical cholinergic innervation. The possible sources of this innervation are also discussed.
Animals↗
Skin dose near compensating filters in radiotherapy.
In radiotherapy treatments with MV beams, the use of tissue compensators affects the dose to the skin. Methods of calculating the relative skin dose (RSD) are described and a formula is derived to predict the contribution of a tissue compensator to the RSD. Measurements of RSD for various field sizes and distances from the compensator are presented.
Filtration↗
Development of cholinergic neurons in the septal/diagonal band complex of the rat.
In the present study we employed immunohistochemical techniques using a polyclonal antibody against choline acetyltransferase (ChAT) to determine the distribution and cytological features of cholinergic neurons in the developing septal/diagonal band complex of the rat. ChAT-positive perikarya were first clearly detected in this region on embryonic day 17, although the neurons were faintly labeled and lacked the cytological details found in the adult. After birth we observed a dramatic increase in the intensity of the immunolabeling which continued until postnatal day 23. Thereafter, the ChAT-positive neurons assumed their adult-like characteristics.
Animals↗
Response of septal cholinergic neurons to axotomy.
In the present study we employed quantitative morphometric techniques to assay the response of septal cholinergic neurons following unilateral transection of the fimbria/fornix and supracallosal stria. Analysis of 50-micron-thick tissue sections with a Quantimet 920 image analysis system demonstrated a reduction in ChAT immunoreactivity as early as 1 day following denervation. This decrease was associated with a drop in the number of labeled cells ipsilateral to the lesion and a decrease in the area of cholinergic perikarya on the lesioned and nonlesioned side of the septum. The response at 1 day, however, was transient, and at 4 days the number of labeled neurons was not significantly different from controls. By 8 days we observed a dramatic reduction in the number and size of ChAT-positive cells ipsilateral to the lesion and a reduction in the size of cholinergic perikarya on the contralateral (i.e., nonlesioned) side. These values persisted throughout the remainder of the study. To assess more completely the morphologic response of neurons to axotomy than can be determined in 50-micron-thick tissue sections, we embedded the adjacent immunolabeled tissue section in Epon and then serially sectioned it to a thickness of 0.75-1.0 micron. By using this method, we were able to measure the area, length, and width of the cell, the area of the nucleus and nucleolus, and the position of the nucleus (i.e., eccentricity). Measurements were performed on ChAT-labeled and nonlabeled cells. The results of our studies demonstrate that cholinergic and noncholinergic cells responded to axotomy in a characteristic yet different fashion from each other and that this response could be quantitatively assayed. In general, labeled and nonlabeled cells on the lesioned side of the septum shrink in response to denervation. This shrunken state was reflected in measurements of cellular area, length, width, and nuclear area. Moreover, other measurements of cellular morphology (i.e., area of the nucleolus, position of the nucleus) indicate that none of the neuronal populations examined in the present study displayed morphologic evidence of regeneration. Our results indicate a dramatic loss of cholinergic perikarya ipsilateral to the lesion. Moreover, although a few neurons do persist they do so in a shrunken state. These data provide an essential baseline for the second study in this series, which will evaluate the effect of nerve growth factor on the survival of denervated septal neurons.
Animals↗
Distribution of choline acetyltransferase-containing neurons of the hypothalamus.
A system of small to medium size choline acetyltransferase (ChAT)-containing neurons has been identified in rat, monkey and human hypothalamus. A highly sensitive polyclonal anti-human placental ChAT rabbit serum, combined with a nickel ammonium sulfate second antibody intensification method, was used to identify these relatively weakly staining ChAT-positive neurons. The most prominent hypothalamic group consisted of small neurons in the infundibular (arcuate) nucleus. Fibers extended towards the infundibulum. Other ChAT-positive cells were not identified with specific hypothalamic nuclei but were scattered loosely in the surrounding matrix. They fell into two broad complexes: a medially distributed one close to the third ventricle and running rostrocaudal to caudoventral; and a lateral one distributed principally in the region of the medial forebrain bundle. The most laterally placed hypothalamic ChAT-positive neurons slightly overlapped with the large, intensely staining cells of the medial basal forebrain cholinergic complex. The identification of these cells helps to account for previous biochemical and pharmacological studies which have strongly indicated the presence of intrinsic cholinergic neurons in the hypothalamus.
Animals↗
Vestibular and cochlear efferent neurons in the monkey identified by immunocytochemical methods.
Attempts were made to identify vestibular (VEN) and cochlear (CEN) efferent neurons in the squirrel monkey using retrograde transport of horseradish peroxidase (HRP) and immunocytochemical methods. HRP implants in the ampulla of the lateral semicircular duct retrogradely labeled cells of VEN bilaterally and some cells of CEN. VEN located lateral to the rostral part of the abducens nucleus formed a compact collection of cells, all of which were immunoreactive only to antisera for choline acetyltransferase (ChAT). CEN, identified by immunoreactivity to ChAT were located at the hilus of the lateral superior olive (LSO), along the lateral border of the LSO and sparsely near lateral parts of the ventral trapezoid nucleus (VTN). A small number of cells and fibers near the border of the VTN and lateral to the LSO were immunoreactive for leucine enkephalin (L-ENK). Fibers immunoreactive for L-ENK also were identified in the hilus of the LSO. No cells of the superior olivary complex were immunoreactive for antisera to ChAT, L-ENK, substance P, gamma-aminobutyric acid or glutamic acid decarboxylase. Cells of VEN and CEN can be identified by their immunoreactivity to ChAT, and some cells and fibers of CEN also contain L-ENK.
Animals↗
Studies on detergent released choline acetyltransferase from membrane fractions of rat and human brain.
The relationship between soluble and membrane choline acetyltransferase (ChAT) was studied. Differential solubilization of rat and human brain yielded ChAT in the soluble and membrane fractions. The addition of 1% Triton X-100 to membrane fractions resulted in a release of ChAT. A comparable release of lactate dehydrogenase was also observed. The Triton released ChAT and soluble ChAT from rat and human brain were efficiently purified by immuno-affinity chromatography. A single molecular weight of 68,000 was observed for both forms of rat and human brain ChAT. Epitope maps produced from both forms of human brain ChAT were identical. It is concluded that Triton released ChAT is identical to soluble ChAT and simply represents occluded soluble ChAT.
Animals↗
Relation of pontine choline acetyltransferase immunoreactive neurons with cells which increase discharge during REM sleep.
The purpose of this study was to determine whether neurons in the medial pontine reticular formation with high discharge rates during REM sleep could be localized in regions of the brainstem having neurons displaying choline acetyltransferase immunoreactivity. Six cats were implanted with sleep recording electrodes and microwires to record extracellular potentials of neurons in the pontine reticular formation. Single-units with a S:N ratio greater than 2:1 were recorded for at least two REM sleep cycles. A total of 49 units was recorded from the pontine reticular formation at medial-lateral planes ranging from 0.8 to 3.7 mm. The greatest proportion of the units (28.6%) showed highest discharge during active waking and phasic REM sleep compared to quiet waking, non-REM sleep, transition into REM sleep or quiet REM sleep periods. A percentage (20.4%) of the cells had high discharge associated with phasic REM sleep periods while 8.2% of the cells showed a progressive increase in discharge from waking to REM sleep. Subsequent examination of the distribution of choline acetyltransferase immunoreactive cells in the PRF revealed that cells showing high discharge during REM sleep were not localized near presumed cholinergic neurons. Indeed, we did not find any ChAT immunoreactive somata in the medial PRF, an area which has traditionally been implicated in the generation of REM sleep. These results suggest that while increased discharge of PRF cells may be instrumental to REM sleep generation, these cells are not cholinergic.
Animals↗
Choline acetyltransferase immunoreactivity in neuritic plaques of Alzheimer brain.
We have observed dystrophic choline acetyltransferase (ChAT)-positive processes surrounding the amyloid core of neuritic plaques in human neocortex, amygdala and hippocampus, using a polyclonal anti-human ChAT antiserum. These data, and those from studies of the aged monkey by other investigators, provide a morphologic counterpart for the biochemical abnormality of the cholinergic system in Alzheimer's disease and senile dementia of the Alzheimer type.
Aged↗
Cholinergic innervation displays strikingly different laminar preferences in several cortical areas.
A new rabbit polyclonal antiserum against choline acetyltransferase (ChAT) reveals that cholinergic innervation of the cortex varies strikingly among different cytoarchitecturally defined areas in the rat neocortex. These findings suggest that cholinergic transmission may be integrated differently into the local circuitries of various regions of the cerebral cortex. In addition, the pattern of staining observed with acetylcholinesterase histochemistry, which has been used for many years to demonstrate putative cholinergic fibers, only partially matches the staining pattern obtained with the more specific cholinergic marker, ChAT.
Acetylcholinesterase↗
Immunohistochemical staining of cholinergic neurons in the human brain using a polyclonal antibody to human choline acetyltransferase.
Antibodies against human placental choline acetyltransferase (ChAT) were used to immunohistochemically stain cholinergic neurons in the neostriatum and nucleus basalis of Meynert in human brain. Cells in both regions were intensely stained as were nerve fibers. Comparable cells were stained in these same brain regions in the rat. This anti-human ChAT antibody will enable the further detailed characterization of cholinergic neurons in the human brain in both health and disease.
Animals↗
A comparative study of choline acetyltransferase from normal and Alzheimer brain.
A comparative study was made of the enzyme choline acetyltransferase (ChAT) from normal and Alzheimer (senile dementia of the Alzheimer type) brain. The number of molecular weight and charge forms of the enzyme were determined in the caudate region of both brains. Efficient purification of active ChAT was achieved using immuno-affinity purification. It was shown that the purified enzyme was identical in both cases, exhibiting a single charge (apparent pI approximately 8.2) and a single molecular weight (mol. wt. = 68,000). The idea of a selective loss of one particular isoform to explain the reduced levels of ChAT observed in Alzheimer's disease can be ruled out.
Alzheimer Disease↗
Immunoaffinity purification of human choline acetyltransferase: comparison of the brain and placental enzymes.
A rapid and efficient immunoaffinity purification procedure has been developed for human placental choline acetyltransferase (ChAT). Using this procedure, human placental ChAT was purified to homogeneity with high recovery of enzyme activity (50-60%). Purified ChAT was used to raise a monospecific anti-human ChAT polyclonal antibody in rabbits. A comparison of the physical properties of ChAT was made between the enzymes purified from human brain and human placenta. Only one form of the enzyme exists in either tissue, having identical molecular weights of 68,000 and a single apparent pI of 8.1. A more detailed comparison of the two enzymes using peptide mapping and epitope mapping indicates identity between the brain and placental enzymes.
Amino Acids↗
On the scene: Stanford University. An evolution of marketing in nursing.
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California↗
Legally speaking. Disfigured by a violent patient: a case - and comment.
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Adult↗