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Biomedical subjects

D M Jenkinson

Publications and source records attributed to D M Jenkinson.

At least 37 records · Page 2Linked to original sources
PubMed1987

The effect of washing on the thickness of the stratum corneum in normal and atopic individuals.

The thickness of, and number of cell layers in, the stratum corneum and the living epidermis were determined on frozen sections of washed and unwashed skin from normal and atopic individuals of both sexes. The stratum corneum of atopic patients was thinner and had fewer layers of dead cells and intercellular lipid than normal, although the living epidermis was thicker. Regular washing with soap and water had no appreciable effect on the dimensions of the living epidermis of either group but caused a reduction in the number of cell layers and the amount of sudanophilic material in the stratum corneum of both. In atopic patients little surface lipid remained, suggesting that washing with soap and water may be detrimental to the barrier function of the stratum corneum in such patients.

Administration, Topical↗
PubMed1987

Effects of topically-applied antiperspirant on sweat gland function.

In subjects exposed to a hot environment, short-term topical pretreatment with aluminium zirconium tetrachlorhydrate delayed the onset of visible sweating although it failed to prevent the response. The delay was considered most probably to be due to the occlusive action, in the duct within the upper epidermis, of aluminium-containing conglomerates, which disappear after continuous sweating. However, microanalytical evidence indicated that ionic transport within the fundus secretory cells was also modified.

Administration, Topical↗
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↗
PubMed1986

Route of passage of cypermethrin across the surface of sheep skin.

14C cypermethrin applied topically to the dorsal surface of sheep moved radially across the skin within the stratum corneum of the epidermis at a rate which exceeded 11 cm h-1. This spread was accompanied by some dermal infiltration which was most marked at the site of application.

Administration, Topical↗
PubMed1986

Output of triglyceride from the sebaceous gland and to the skin surface of cattle.

Radiolabelled fatty acids, when injected intradermally into cattle skin, were largely incorporated into the triglyceride and phospholipid fractions of the sebaceous gland lipids. Linoleic acid was incorporated into the triglycerides to a greater extent than oleic or palmitic acids, whereas the phospholipids had a greater affinity for palmitic acid. The peak uptake of linoleic acid into the glandular triglyceride fraction was at about 61 hours compared with 52 hours and three hours for oleic and palmitic acids. Radioactively 14C labelled triglycerides appeared on the skin surface within one day of intradermal injection of 14C linoleic acid. At an ambient temperature of 20 degrees C, a single output-peak occurred at nine days while at 35 degrees C two peaks at four and eight to nine days were observed. From the data an estimate of 6.5 days for the mean storage time of sebum triglycerides in the hair follicle canal at 20 degrees C has been made.

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↗
PubMed1985

Incorporation in vitro of 14C fatty acids into bovine sebaceous gland and dermal lipids.

A study has been made of the incorporation in vitro of 14C palmitic, oleic and linoleic acids into the skin lipids of cattle. Linoleic acid was incorporated into the triglyceride (triacylglycerol) fraction of the sebaceous gland lipid at a greater rate than palmitic and oleic acids. Its incorporation was much greater when presented as a free acid than when presented either as cholesteryl linoleate or linoleoyl lecithin. However, the ability of cholesteryl ester and phospholipid to make a substantial indirect contribution of linoleic acid to sebum triglyceride synthesis by hydrolytic release of fatty acid was indicated. The association between the observed preferential incorporation of linoleic acid into the sebum triglycerides and the uniquely unsaturated triglycerides found on the skin surface of cattle is discussed.

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↗
PubMed1984

Lipid composition of the bovine epidermis.

In contrast to skin surface or sebum lipid, cattle epidermis was found to contain a lower proportion of wax ester and unesterified fatty acid and a high proportion of triglyceride. The epidermal triglycerides differed significantly in their fatty acid composition from those of the skin surface and sebum. In particular they contained extremely low levels of linoleic acid. It is concluded that the skin surface triglycerides and most likely the other major lipid fractions of the bovine skin surface are derived mainly from sebum.

Animals↗
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↗
PubMed1982

Preparation of cryosections with a modified Sorvall MT2B ultramicrotome and cryoattachment.

The Sorvall MT2B ultramicrotome and cryoattachment were modified to extent the duration of cutting and to overcome problems in tissue preparation. Microtome and cryochamber were encased and surrounded by an atmosphere of dry nitrogen gas at room temperature. A specially designed cold block sited within the box close to the microtome enabled tissues to be trimmed at low temperatures in the dry environment. Tissues could be readily visualized both on the trimming block and in the chamber with the existing microscope modified to improve its working distance and lighting system. During transfer from storage in liquid nitrogen, through the trimming procedure, to arrival in the cryochamber, the temperature of tissues as determined using thermocouples embedded in PVP on a stub, never exceeded 140 K. Although there was a considerable standing temperature gradient within the cryochamber, the cutting environment, specimen and edge of the knife were thermally stable. Sections could be routinely cut dry and freeze-dried within the chamber, if desired.

Animals↗
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↗