Search PubMed⌕ Search

Biomedical subjects

I Montgomery

Publications and source records attributed to I Montgomery.

At least 37 records · Page 2Linked to original sources
PubMed1986

Passage of lanthanum through the intercellular spaces of the sebaceous gland.

Lanthanum introduced intradermally into cattle, sheep, goats, ponies and rats penetrated into the sebum through the intercellular spaces of the sebaceous gland. It is concluded that the sebaceous gland is permeable to the passage of small molecules outwards and probably in some circumstances inwards. Since the constituents of sebum are not all produced by necrosis it is likely that the sebaceous gland is not a simple holocrine gland.

Animals↗
PubMed1985

Comparative studies of the ultrastructure of the sebaceous gland.

Three-dimensional reconstructions and ultrastructural evidence on the sebaceous glands of man and domestic animals indicate that sebum is produced from a column of developing and degenerating cell populations derived from peripheral progenitor cells at the base of the lobe in a manner analogous to hair growth. The remainder of the peripheral cells apparently have no direct involvement with sebocyte production; those towards the neck of the gland contribute keratin to the secretory product.

Adult↗
PubMed1985

The effects of thermal stimulation on the ultrastructure of the human atrichial sweat gland. II. The duct.

The duct of the human atrichial sweat gland, after thermal stimulation, exhibited increased cytoplasmic vesiculation, particularly of the luminal cells, a widening of the intercellular spaces, and the presence of particulate matter in the lumen. The luminal cells of the coiled zone also displayed varying degrees of apical disruption, most probably due to filtration of cell fluid through the terminal web of microfilaments. This zone seems to have a secretory as well as an absorptive role. Specialized junctions (intercellular bridges, gap junctions and tight junctions) were found amongst the basal and luminal cells of the wall of the ascending duct.

Cytoplasm↗
PubMed1985

Ultrastructural variations in the sweat glands of anhidrotic horses.

The ultrastructure of sweat glands from the skin of free sweating horses was compared with that of glands from anhidrotic cases. Evidence of atrophied and abnormal sweat glands in the anhidrotic horses indicates that the condition involves progressive failure of the glandular mechanism of sweat production.

Animals↗
PubMed1984

The effects of thermal stimulation on the ultrastructure of the human atrichial sweat gland. I. The fundus.

Ultrastructural examination of sweat glands from the human loin before and during heat-induced activity indicated that the sweat is formed from the contents of disrupted cells as well as from the products of secretion. The principal secretory processes appear to be fluid transport and exocytosis of vesicles. However, configurations suggesting microapocrine secretion were also observed. It is concluded that the mechanisms involved in sweat production in man are fundamentally similar to those in animals and the terms 'apocrine' and 'eccrine' should be discarded. The myoepithelial cells which were contracted at the onset of sweating appeared to be under less tension after 3 h of continuous activity.

Adult↗
PubMed1983

Comparative studies of the effect of thermal stimulation on the permeability of the luminal cell junctions of the sweat gland to lanthanum.

Lanthanum injected intradermally in vivo into the skin of cattle, sheep, goats and ponies penetrated the intercellular spaces of the sweat glands. It was not, however, detected in the glandular lumen either visually or by electron probe microanalysis even at elevated ambient temperatures when the animals were sweating. It is concluded that the luminal intercellular connections between epithelial cells in these glands are tight junctions, which remain so during sweating despite the occurrence of cell death and extrusion into the lumen.

Animals↗
PubMed1983

Trazodone enhances sleep in subjective quality but not in objective duration.

Nine volunteer poor sleepers, of mean age 61 years, took trazodone 150 mg nightly for 3 weeks, preceded by 2 weeks and followed by 1 week of matching blanks, in order to examine the effects of electrophysiologically-recorded and subjectively-rated sleep. The second of the initial weeks of matching blanks served as a baseline week. In the subjective ratings, sleep improved in quality on trazodone, significantly so in the first and second weeks of intake, though with significant rebound insomnia on the second withdrawal night. Trazodone halved the frequency of arousals interrupting sleep, and it reduced the time spent in stage 1 (drowsiness). It increased the duration of slow-wave sleep (stages 3 + 4), with a negative rebound following withdrawal. It reduced the time spent in REM sleep, with a rebound above baseline levels after withdrawal. Trazodone did not change total sleep duration, nor the time required to fall asleep. The effects of trazodone were sustained or became enhanced during the period of intake. They persisted for over 24 h after the last dose, and rebound effects were maximal on the second withdrawal night.

Aged↗
PubMed1982

Energy expenditure and total sleep time: effect of physical exercise.

The energy conservation model proposes that the main function of sleep is to lower metabolic requirements periodically and thus to conserve energy. However, certain variations in energy expenditure, such as that produced by physical exercise, have not been found to be consistently related to sleep length. We hypothesized that, because sleep variables may adapt relatively slowly to metabolic changes, the effect of exercise on sleep time would be observed as a function of habitual exercise patterns, not of daily variations. The study consisted of a retrospective analysis of five experiments. Although the design of each experiment was idiosyncratic, all involved physically fit and/or unfit subjects whose sleep was assessed following daytime exercise and/or no exercise conditions. As predicted, fit subjects slept significantly longer than unfit subjects, and daytime exercise had no consistent effect on sleep duration. However, for several reasons, the relevance of the data to the energy conservation model is uncertain.

Adult↗
PubMed1982

The ultrastructure of the sweat gland duct of the ox, sheep and goat before and during sweating.

The duct of the cow, sheep and goat can be divided into two main parts, the intrafollicular region and the intradermal region. Three sub-regions, namely the perifollicular zone, the duct body and the duct/fundus transition zone, can be distinguished within the latter. In the outer portion of the hair follicle, the luminal surface was keratinized but the presence, in the cow and sheep, of surface microvilli with closely associated vesicles deeper within this layer suggested the possibility of a reabsorptive role. The intradermal duct had junctional complexes at the luminal extremity throughout its length. Gap junctions were observed between basal cells only in the lower part of the duct body. Dovetailing between luminal cells in the intradermal duct was barely noticeable in the cow but prominent in the goat. In the duct/fundus transition zone of all three species there was evidence of cell differentiation, the potential significance of which is discussed. There was little change in the ultrastructure of the duct in any of the three species, other than an increase in lumen size, as a result of heat exposure and sweating activity.

Animals↗
PubMed1982

The effects of thermal stimulation on the ultrastructure of the fundus and duct of the equine sweat gland.

Sweating in the horse had little effect on the ultrastructure of the glandular duct, other than on the lumen which enlarged. The fundus secretory cells, which in the resting gland were packed with vesicles, gradually lost them as sweating progressed until, after 4 hours of activity, few remained. Sweat appeared to be largely the product of secretion (a) by fluid transport, probably involving a region of complex cellular interdigitations adjacent to the basement membrane and (b) by exocytosis of vesicles, although a secondary mechanism of vesicle loss by micro-apocrine secretion may occur. However, the products of cell death also contribute to sweat formation. The myoepithelium appeared contracted throughout. The function of the lower duct body, where complex basal infoldings of the luminal cells penetrated to the basement membrane, may differ from that of the upper portion. Dendritic Langerhans cells were found between the epithelia throughout the duct and fundus.

Animals↗
PubMed1980

Impulsive suicidal behavior.

Previous studies have noted that a considerable proportion of suicidal behavior is impulsive. The present study aimed to ascertain the degree to which this was so and to consider whether impulsive attempters differed from non-impulsive attempters on variables such as demographic and motivational factors and circumstances that surrounded the occurrence of the act. Based on a criterion of less than 5 minutes' premeditation, 40% of two large, consecutive series were judged to have acted impulsively. While few variables differentiated between the two groups, impulsive attempters were less depressed, motivated by the desire to reduce tension, more likely to consider that they would survive, and to report that someone saw them perform the act.

Adult↗
PubMed1979

The ultrastructure of the sweat glands of the ox, sheep and goat during sweating and recovery.

The ultrastructure of the sweat glands of cattle, sheep and goats was studied before, during, and after, exposure of the animals to controlled warm environments. In cattle, sweating induced little ultrastructural change in the gland, although fluid-filled spaces appeared between the myo- and secretory epithelial layers. The mechanism appears to be one of fluid transport and exocytosis of secretory vesicles, which in this species seem to be derived from the Golgi apparatus and/or mitochondria. The glands of the sheep and goat also displayed signs of vesicle exocytosis and of fluid transport during sweating. The sweating 'fatigue' in these species was apparently due to failure of the secretory cells, some of which ruptured and were extruded into the lumen. The evidence during subsequent recovery indicates that neighbouring cells spread to make contact, encase remnants of atretic cells between them and the underlying myoepithelium, and engulf them. Sweat in these species appears to be formed (a) by secretion and (b) from cells which can no longer meet the demands of stimulation. The role in sweating of cell replacement, and of undifferentiated cells found between the myo- and secretory epithelia, is discussed.

Animals↗
PubMed1978

Studies on the nature of the peripheral sudomotor control mechanism.

Electron microscopical studies of the sweat glands of the body surface of the cow, sheep, goat and cat demonstrated that there were few nerves or blood vessels near the glands. No varicosities were found within 10 micron of the glands, and the small number of unmyelinated nerve bundles traced were over 1.5 micron from the glandular myoepithelium, and situated outside a fibrocyte sheath surrounding the glands. It was concluded that the sweat glands of these species are not innervated. Unmyelinated nerve fibres were more abundant around, and were closer to, the sweat glands of man, the horse and cat footpads, and varicosities were observed within the fibrocyte sheath close enough to have a direct influence on the glands. It is postulated from the comparative evidence that the basic sudomotor mechanism is the same in all species, involving the action of adrenergic and cholinergic nerves on the cutaneous blood vessels and local catecholamine transfer to the gland; and that in species such as man where the blood supply and sympathetic nerves are in close proximity to the glands, transmitters released at the sympathetic nerve endings, in particular acetylcholine, will, in addition, have a direct action on the glands.

Adult↗