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S W Carmichael

Publications and source records attributed to S W Carmichael.

At least 55 records · Page 3Linked to original sources
PubMed1988

Effect of acute and chronic spinal transection on evoked secretion of adrenal medullary catecholamines in the cat.

Eight cats were spinally transected at T3. After an acute (0-5 days) or chronic (15-37 days) period, animals were rendered decerebrate and the effects of visceral (bladder distention) and somatic (sciatic nerve stimulation) stimuli were examined. Epinephrine, norepinephrine and dopamine levels were measured in plasma collected from the left adrenolumbar vein; heart rate and blood pressure were continuously monitored. In chronic animals both visceral and somatic stimuli most frequently evoked prominent increases in blood pressure and the secretion of adrenal medullary catecholamines; the same stimuli caused little change in these parameters in acute animals. These data indicate that a condition similar to the clinical syndrome of autonomic hyperreflexia may be elicited in the chronic spinally transected cat, and that this condition is accompanied by a notable activation of the adrenal medulla.

Acute Disease↗
PubMed1987

Ultrastructural demonstration of exocytosis in intact and saponin-permeabilized cultured bovine chromaffin cells.

Exocytosis is the release of intracellular vesicular contents directly to the cell exterior after fusion of the vesicular and plasma membranes. It is generally accepted as the process by which transmitters and hormones are released from neurons and neurosecretory cells. There is overwhelming biochemical evidence that exocytosis is the mechanism by which catecholamines are released from adrenal chromaffin cells. With the exception of the hamster, however, there is little ultrastructural evidence to support such a mechanism. We have used a modified in vitro tannic-acid method to visualize exocytosis by transmission electron microscopy in intact and saponin-permeabilized bovine chromaffin cells. When cells are exposed to tannic-acid-containing medium, the content of vesicles involved in exocytosis is coagulated in situ as the vesicle opens to the exterior. Numerous exocytotic profiles were observed. The exposed vesicle contents appeared more granular than those of vesicles in the cell interior. Tannic acid also made the plasma membrane more distinct. Small holes were apparent in the plasma membrane of saponin-treated cells, with little disruption of underlying cytoplasmic structure. Furthermore, when these cells were stimulated with calcium, exocytosis was evident only at regions of intact plasma membrane, not at the holes. Parallel measurements of secretion showed no secretion in the presence of tannic acid. Pretreatment with tannic acid prevented subsequent secretion by intact cells and markedly reduced that of permeabilized cells, indicating a probable change in the nature of the plasma membrane.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Opossum adrenal medulla: I. Postnatal development and normal anatomy.

The anatomy and histology of the adrenal gland in the adult opossum were found to be typical for mammals. The development of the adrenal medulla was also found to follow the typical mammalian pattern. Primitive sympathetic cells were found in both intra- and extra-adrenal locations in the newborn at a time when chromaffin precursor cells were migrating to the adrenal anlage. Pheochromoblasts first appeared within the forming medulla where at a later stage chromaffin cells could be observed forming columns of cells between adjacent sinusoids. Unlike in other mammals, much of this development takes place postnatally when the neonate is in the mother's marsupium. The value of the developing opossum adrenal medulla as an experimental model is stressed, since a significant amount of development takes place in an environment that is accessible to experimental manipulation.

Adrenal Medulla↗
PubMed1987

Opossum adrenal medulla: II. Differentiation of the chromaffin cell.

The ultrastructure of the opossum adrenal medulla was examined in its postnatal development. Maturation of chromaffin cells and genesis of chromaffin vesicles were of particular interest. The primitive sympathetic cell was seen to contain few organelles with no apparent polarity. Initial pheochromoblasts contained more organelles with some polarity. Endoplasmic reticulum and the Golgi complex increased as the pheochromoblasts matured, which suggested increased synthetic activity. Structures resembling Golgi/endoplasmic reticulum/lysosome (GERL) systems were seen in the pheochromoblasts. It is suggested that some of the components of the chromaffin vesicle may be processed by the GERL while others come directly through the Golgi complex. It is stressed that the developing pheochromoblast in the opossum presents an interesting model in which to study the genesis of the chromaffin vesicle.

Adrenal Medulla↗
PubMed1987

Locating the lateral antebrachial cutaneous nerve.

Dissections of 20 antebrachial specimens were done to define the location of the proximal lateral antebrachial cutaneous nerve, which is the distal sensory extension of the musculocutaneous nerve. Our findings varied from those noted in most anatomic and surgical texts in that the nerve emerges from the lateral aspect of the biceps tendon at the level of the interepicondylar line. At the point defined, the distribution of the nerve in ten volunteers was successfully anesthetized with 1.5 ml of 1% lidocaine. The accurate anatomic localization of this nerve should be of interest to surgeons and anesthesiologists in supplementing failed axillary blockade, in diagnosing and treating the musculocutaneous impingement syndrome, in harvesting the proximal nerve for diagnostic tests or donor graft purposes, and in differentiating the sensory distribution of this nerve from that of the radial nerve.

Anesthetics, Local↗
PubMed1986

Androgen and estrogen effect on guinea pig seminal vesicle muscle: a combined stereological and biochemical study.

A combined electron microscopic stereological and biochemical study of the smooth muscle cells of guinea pig seminal vesicles was performed in intact, castrated, castrated and dihydrotestosterone- or estradiol-treated adult animals. Castration led to cell atrophy as determined stereologically by a decreased single cell volume and biochemically by no change in DNA content coupled with an increase in the DNA concentration. Treatment of castrates with dihydrotestosterone restored both the stereological and biochemical parameters of the cell size to slightly supranormal levels. The estrogen-induced increase in muscle weight and DNA content appeared to be due only to hyperplasia of muscle cells and not to a proliferation of fibroblasts or to infiltration by inflammatory cells. In all treatment groups, including the estrogen-treated castrates, more than 95% of the cells in the tissue were smooth muscle cells, and there was no evidence that polyploidy contributed to changes in DNA levels. In addition, in the estrogen-treated muscles, DNA concentration remained high, and the stereologically determined cell size remained low. Therefore, both morphological and biochemical evidence indicate that androgen induces hypertrophy, whereas estrogen induces hyperplasia of muscle cells. The correction of stereological and biochemical data validates the application of stereological cell size determination for smooth muscle cells in organs that hardly can be separated into stromal and epithelial components; eg, the prostate.

Animals↗
PubMed1985

Supplemental clinical dissections for freshman gross anatomy.

This paper describes a series of nine short clinically oriented dissection exercises as supplements for freshman gross anatomy courses. These procedures heighten and focus student interest, and they do not extensively lengthen the time required to accomplish the regular dissection assignments. The exercises are: lumbar puncture, anterior approach for shoulder arthroplasty, acromioclavicular dislocation, fenestration of the diaphragm, appendectomy, cholecystectomy, display of the facial nerve as in parotidectomy, posterior approach for hip arthroplasty, and injuries to the knee ligaments and meniscectomy.

Acromioclavicular Joint↗
PubMed1985

Histochemical localization of monoamine oxidase types A and B in the adrenal gland.

The distribution of monoamine oxidase types A and B within the adrenal gland was studied in several mammals by histochemical methods. Controls showed that the methods were valid. The bovine adrenal medulla contained mostly the B type enzyme, distributed heterogeneously, with some A type associated with endothelium, nerves, and cells surrounding the nerves. The bovine adrenal cortex showed a marked zonation of the two types of monoamine oxidase. The zona glomerulosa contained the B type enzyme and the zona fasciculata and zona reticularis contained the type A enzyme. The adrenal medulla of the dog, cat, and rat demonstrated relatively little enzyme activity and it appeared to be both type A and B. The adrenal cortex of these animals appeared to contain mostly the B type enzyme, except the canine zona reticularis, which contained some A type monoamine oxidase as well.

Adrenal Cortex↗
PubMed1984

Acetylcholinesterase activity of adrenal chromaffin vesicles.

Biochemical studies have given conflicting interpretations as to the localization of acetylcholinesterase within adrenal chromaffin cells. Previous histochemical studies found no reaction product on the chromaffin vesicles, although some biochemical studies suggest that a form of the enzyme is present. Sensitive histochemical procedures, with the appropriate controls, suggest a small amount of acetylcholinesterase is associated with chromaffin vesicles.

Acetylcholinesterase↗
PubMed1984

Adenylate cyclase activity of adrenal chromaffin vesicles.

Biochemical studies have provided conflicting interpretation as to the presence of adenylate cyclase in or on the chromaffin vesicle of the adrenal medulla. Various histochemical procedures were employed and a slight amount of reaction product was detected. It is suggested that a small amount of adenylate cyclase is associated with the chromaffin vesicle.

Adenylyl Cyclases↗
PubMed1983

The adrenal chromaffin vesicle: an historical perspective.

Unique histochemical properties of the adrenal medulla were first described in the middle of the nineteenth century. The most important histochemical reaction of this glandular tissue was with chromate salts which became known as the chromaffin reaction. The terms chromaffin cell and chromaffin vesicle stem from this reaction. During the first half of this century it was established that the chromaffin cells of the adrenal medulla are an integral part of the sympathetic nervous system and play a role in the response to acute stress. The chromaffin cell is recognized as a modified postganglionic sympathetic neuron and as such has proven to be an accessible and valuable model. Thirty years ago it was found that the secretory vesicle of the chromaffin cell could be isolated. This has led to the use of the chromaffin vesicle as a model for study of neurosecretory vesicles. This symposium presents an overview of recent work in various areas that have centered on the chromaffin vesicle.

Adenosine Triphosphate↗
PubMed1983

The effect of a MAO inhibitor on reserpine-induced secretion of catecholamines from the adrenal medulla of the rose-ringed parakeet.

The effect of MAO inhibitor on reserpine-induced release of catecholamines from the adrenal medulla of the rose-ringed parakeet was investigated in this biochemical, histochemical, and ultrastructural study. The MAO inhibitor provided some blockade of epinephrine secretion and was ineffective in blocking norepinephrine secretion. Differences between birds and mammals were noted, suggesting that different mechanisms of catecholamine release may be operating in the two classes.

Adrenal Medulla↗