Biomedical subjects

M J Coleman

Publications and source records attributed to M J Coleman.

6 recordsLinked to original sources

PubMed1992

Distribution of modulatory inputs to the stomatogastric ganglion of the crab, Cancer borealis.

The pyloric and gastric mill neural networks in the crustacean stomatogastric ganglion receive modulatory inputs from more anteriorly located ganglia via the stomatogastric nerve. In this study we employed biocytin backfilling and immunostaining, as well as electron microscopy, to determine the origin of these inputs in the crab, Cancer borealis. Fiber counts from electron micrographs of sections through the stomatogastric nerve showed that this nerve contains 55-60 medium to large diameter fibers (1-13 microns). These fibers were individually wrapped by several layers of membrane, presumably glial in origin. There was also a single cluster of jointly wrapped, small diameter (< 1 micron) fibers that may originate from peripheral sensory somata. Biocytin backfills revealed that approximately two thirds of the individually wrapped fibers in this nerve originate from somata in the other three ganglia of the stomatogastric nervous system, including the paired commissural ganglia and the single oesophageal ganglion. There were approximately 20 biocytin-labeled somata in each commissural ganglion and 3 somata in the oesophageal ganglion. An additional ten somata were localized to the stomatogastric ganglion itself. This accounts for nearly all of the medium to large diameter fibers in the stomatogastric nerve. We used double-labeling with backfills and immunocytochemistry to determine that there are two proctolin-immunoreactive neurons and four FMRFamide-like immunoreactive neurons among the biocytin-labeled neurons in each commissural ganglion. Both peptides modulate neural network activity in the stomatogastric ganglion.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

PubMed1992

Rostrocaudal differences in morphology and neurotransmitter content of cells in the subretrofacial vasomotor nucleus.

The rostral ventrolateral medulla (RVLM) contains sympathoexcitatory neurons that exert a powerful control over the sympathetic outflow to the cardiovascular system. In the cat there is a concentration of such neurons (but not neurons subserving other functions) within a narrow longitudinal column in the RVLM termed the subretrofacial (SRF) nucleus. Furthermore, it has been suggested that there are subgroups of cells, located at different rostrocaudal levels of the SRF nucleus, that preferentially or exclusively control different vascular beds (e.g. in the kidney and hindlimb). The aim of this study was to map quantitatively the rostrocaudal distribution within the nucleus of different cell types, defined according to morphological and/or chemical criteria, and to correlate this with the regional vasomotor effects (in hindlimb and kidney) evoked by stimulation of SRF cells at the corresponding rostrocaudal levels. SRF cells were highly heterogeneous with respect to both their morphology and chemical properties. They varied greatly in size (equivalent diameter ranging from 10-40 microns) as well as in shape and orientation. An immunohistochemical examination using the avidin-biotin procedure revealed that many SRF cells (estimated 57% of all SRF cells) were immunoreactive for tyrosine hydroxylase (TH, a marker of catecholamine cells). In addition, there were SRF cells immunoreactive for neuropeptide Y (NPY, 11% of total), enkephalin (ENK, 16% of total), and serotonin (5HT, 10% of total), but not for substance P, galanin or somatostatin. Different cell types, defined according to their morphology and/or chemical properties, were unevenly distributed throughout the nucleus. In the most caudal part of the SRF nucleus, virtually all cells were TH-positive, and the large majority (estimated 80%) were NPY-positive, suggesting that many cells at this level contained both TH and NPY. In contrast, in the most rostral part of the SRF nucleus, only 30% of cells were TH-positive, and no NPY-positive cells were observed. Both 5HT- and ENK-positive cells were found throughout the rostrocaudal extent of the nucleus, but predominantly within its rostral part. Furthermore, TH-positive cells in the rostral SRF nucleus were on average significantly larger (mean equivalent diameter 18-43% greater) than TH/NPY-positive cells in the caudal part of the nucleus, but smaller than 5HT- or ENK-positive cells at the same level. Overall, rostral cells (regardless of their chemical type) were larger than caudal cells within the SRF nucleus (mean equivalent diameter 13-28% greater).(ABSTRACT TRUNCATED AT 400 WORDS)

Anesthesia↗

PubMed1979

Antral patch esophagoplasty. A new procedure for acid-peptic esophageal stricture.

Antral patch esophagoplasty is a new procedure for intractable fibrous stricture of the esophagus secondary to acid-peptic reflux. A full-thickness patch of gastric antrum, supplied by a pedicle based on the left gastroepiploic vessels, is inserted, mucosal surface to lumen, into the opened stricture. A fundoplication is done below the esophagoplasty to prevent reflux. The functional results were excellent in five of six patients. The procedure may have application also in other types of benign esophageal stricture.

Aged↗

PubMed1979

Gastric patch esophagoplasty: an experimental study.

To determine whether the use of pedicled full-thickness gastric patches would be feasible and safe in esophageal reconstruction, studies were undertaken in eleven dogs. The results demonstrate that patches containing parietal cell mucosa are likely to produce localized adjacent esophagitis. Patches containing antral mucosa do not produce esophagitis and are not associated with a subsequent increase in circulating serum gastrin levels.

Animals↗

PubMed1975

The adaptation of cochlear and brainstem auditory evoked potentials in humans.

The adaptation of the responses from the cochlear nerve and the auditory brainstem nuclei was studied using a burst of four clicks as the stimulus. Nine experimental conditions were obtained from three stimulus levels (60, 70 and 80 dB SL) and from three intervals between click in the burst (15, 24 and 32.5 msec). Six subjects were each tested three times for each of the experimental conditions and the techniques used and results obtained are summarized. Various models of the adaptation of the brainstem responses are proposed which predict different results. The results for the adaptation of the N1 response are basically in agreement with previous work, and the more central brainstem responses showed less adaptation than the peripheral responses. These findings may be explained by postulating different adaptation mechanisms for the peripheral and central responses. The 60dB stimulus level condition gave rise to more adaptation than the 80dB level, and this is in agreement with studies of low and high threshold reception systems reported elsewhere.

Adaptation, Physiological↗

PubMed1975

Chondrosarcoma of the maxillary antrum presenting as exophthalmos.

A Papau New Guinean patient with a chondrosarcoma of the maxillary antrum producing exophthalmos is presented. The importance of considering causes other than thyrotoxicosis in the aetiology of exophthalmos is stressed and a summary of the clinical features, pathology and management of the tumour is given.

Child↗