Ultrastructure of the hyperhidrotic eccrine sweat gland.

BACKGROUND: Hyperhidrosis is the secretion of inappropriately large amounts of sweat by eccrine glands; it can be very debilitating. Little is known of the causes of primary hyperhidrosis. OBJECTIVES: To determine whether the glands exhibit any structural abnormality in primary hyperhidrosis. METHODS: Skin biopsies were obtained from the axilla (n = 6) or neck (n = 2) of individuals aged 26-62 years with primary hyperhidrosis and from five age- and sex-matched normal individuals, with informed consent and ethical committee approval. Samples were prepared by standard methods for light and electron microscopic examination. RESULTS: All characteristics observed in the hyperhidrotic specimens were consistent with the changes seen in normal glands following strong activation: degranulation of the granular (dark) cells, dilatation of the basolateral infoldings and the canaliculi of the non-granular (clear) cells, contraction of the myoepithelial cells and thickening of the basal lamina, and presence of cellular debris including lipid droplets in the gland lumen. Pathological changes were not observed. CONCLUSIONS: The present finding of the absence of structural defects in the glands indicates that future studies should concentrate on the investigation of neurohumoral or secretory cell metabolic abnormalities.

Incidence of exercise-induced bronchospasm in Olympic winter sport athletes.

PURPOSE: The purpose of this project was to determine the incidence of exercise-induced bronchospasm (EIB) among U.S. Olympic winter sport athletes. METHODS: Subjects included female and male members of the 1998 U.S. Winter Olympic Team from the following sports: biathlon, cross-country ski, figure skating, ice hockey, Nordic combined, long-track speedskating, and short-track speedskating. Assessment of EIB was conducted in conjunction with an "actual competition" (Olympic Trials, World Team Trials, World Cup Event, U.S. National Championships) or a "simulated competition" (time trial, game), which served as the exercise challenge. Standard spirometry tests were performed preexercise and at 5, 10, and 15 min postexercise. An athlete was considered EIB-positive based on a postexercise decrement in FEV1 > or = 10%. RESULTS: For the seven sports evaluated on the 1998 U.S. Winter Olympic Team, the overall incidence of EIB across all sports and genders was 23%. The highest incidence of EIB was found in cross-country skiers, where 50% of the athletes (female = 57%; male = 43%) were diagnosed with EIB. Across the seven sports evaluated, the prevalence of EIB among the female and male athletes was 26% and 18%, respectively. Among those individuals found to be EIB-positive were athletes who won a team gold medal, one individual silver medal, and one individual bronze medal at the Nagano Winter Olympics. CONCLUSIONS: These data suggest that: 1) EIB is prevalent in several Olympic winter sports and affects nearly one of every four elite winter sport athletes; 2) the winter sport with the highest incidence of EIB is cross-country skiing; 3) in general, EIB is more prevalent in female versus male elite winter sport athletes; and 4) athletes may compete successfully at the international level despite having EIB.

Anterior knee pain: a clinical comparison of rehabilitation methods.

OBJECTIVE: To compare different types of rehabilitation for anterior knee pain. DESIGN: Prospective, randomized, blinded, and controlled study of 64 participants with anterior knee pain. SETTING: Outpatient rehabilitation clinic and testing laboratory. PARTICIPANTS: Participants were assigned in randomized fashion to three rehabilitation groups: traditional home rehabilitation (n = 20); physical therapy (n = 21); and home rehabilitation with a modified vastus medialis obliquis (VMO) specific straight leg raise (Muncie method; n = 23). INTERVENTIONS AND MAIN OUTCOME MEASURES: Clinical data was obtained at 0, 2, 6, and 12 weeks. Cybex testing was performed at 0, 6, and 12 weeks. RESULTS: Clinical outcome for the Muncie method indicated a statistically significant improvement in subjective pain and functional impairment ratings. Cybex testing in patients using the Muncie method demonstrated a statistically significant improvement in pain-free isometric contractions and maximum voluntary contraction. There were no significant differences between traditional home therapy and physical therapy. CONCLUSION: Findings suggest that the Muncie method results in improved clinical outcome at a lower cost than traditional home and physical therapy and possibly improved VMO/quadriceps muscle balance. Patients with anterior knee pain may benefit from applying the Muncie method in a home therapy program.

Exercise-induced asthma screening of elite athletes: field versus laboratory exercise challenge.

PURPOSE: The purpose of this study was to compare a laboratory based exercise challenge (LBC) to a field based exercise challenge (FBC) for pulmonary function test (PFT) exercise-induced asthma (EIA) screening of elite athletes. METHODS: Twenty-three elite cold weather athletes (14 men, 9 women) PFT positive for EIA (FBC screened) served as subjects. Twenty-three gender and sport matched controls (nonasthmatics) were randomly selected to establish PFT reference values for normal elite athletes. Before FBC, athletes completed a medical history questionnaire for EIA symptoms. FBC evaluations consisted of baseline spirometry, actual or simulated competition, and 5, 10, and 15 min postexercise spirometry. PFT positive athletes were evaluated in the laboratory using an exercise challenge simulating race intensity (ambient conditions: 21 degrees C, 60% relative humidity). PFT procedures were identical to FBC. RESULTS: 91% of PFT positive and 48% of PFT normal athletes reported at least one symptom of EIA, with postrace cough most frequent. Baseline spirometry was the same for PFT positives and normal controls. Lower limit reference range (MN - 2 SD) of FEV1 for controls suggests that postexercise decrements of greater than approximately -7% indicate abnormal airway response in this population. Exercise time duration did not effect bronchial reactivity; 78% of FBC PFT positives were PFT normal post-LBC. CONCLUSION: Self-reported symptoms by elite athletes are not reliable in identifying EIA. Reference range criterion for FEV1 decrement in the elite athlete postexercise contrasts current recommended guidelines. Moreover, a large number of false negatives may occur in this population if EIA screening is performed with inadequate exercise and environmental stress.

Extracellular ATP can activate autonomic signal transduction pathways in cultured equine sweat gland epithelial cells.

Changes in intracellular free calcium concentration ([Ca2+]i) were monitored in a cell line that was derived from the equine sweat gland epithelium. ATP and closely related compounds could increase [Ca2+]i with a rank order of potency of UTP > or = ATP > ADP >> AMP = adenosine = alpha,beta-methylene-ATP. The responses to ATP and to UTP were initiated by the release of calcium from an internal store and subsequently sustained by calcium influx. The rise in [Ca2+]i thus seems to be mediated by P2U receptors that are coupled to phosphoinositidase C. Some desensitisation of this response developed during repeated stimulation with ATP and this was blocked by staurosporine, an inhibitor of protein kinase C, and augmented by a phorbol ester which acts as an exogenous activator of this enzyme. A protein-kinase-C-dependent inhibitory pathway thus seems to become active during repeated stimulation with ATP. ATP and related compounds could also raise cellular cyclic AMP content. The order of potency was ATP > ADP = AMP = adenosine >> UTP, suggesting that this response is mediated via a separate subclass of P2 receptor. The present results demonstrate that ATP can activate autonomic signal-transduction pathways in cultured equine sweat gland cells and suggest that there may be a purinergic component to the control of secretory activity in the equine sweat gland.

Investigation of stimulus-secretion coupling in equine sweat gland epithelia using cell culture techniques.

When sweat glands isolated from samples of horse skin were explanted and cultured under favourable conditions, they could exhibit cellular outgrowth. This growth could be maintained for 2-4 weeks and these primary cultures were then disaggregated and the resultant cell suspensions used to initiate epithelial cell lines. Secretion from intact equine sweat glands is regulated by beta 2-adrenoceptors and appears to be mediated by cyclic AMP, but there is evidence that calcium may also play a role. Adrenaline could increase the cyclic AMP content of the cultured cells and this response was mediated by beta 2-adrenoceptors. Adrenaline was also able to evoke a small increase in intracellular free calcium ([Ca2+]i) but the pharmacology of this response remains obscure. Adrenaline thus activates at least two potentially important second-messenger signalling pathways which have the capacity to interact, because adrenaline-evoked cyclic AMP formation was inhibited if [Ca2+]i was raised with ionomycin. The chloride permeability of mammalian epithelial cells characteristically rises during secretion, and adrenaline could increase chloride permeability in the cultured epithelia but the cells did not contain cyclic-AMP-dependent chloride channels and so this response was mediated by [Ca2+]i.

Amiloride impairs the cholinergic regulation of potassium permeability in the human sweat gland but not in the rat submandibular gland.

Potassium permeability was monitored in human sweat glands and rat submandibular glands. Acetylcholine increased permeability in both tissues and the responses consisted of transient, calcium-independent and sustained, calcium-dependent components. Amiloride, a drug which inhibits Na(+)-H+ countertransport, impaired the regulation of potassium permeability in sweat glands but not in the submandibular gland. It is suggested that the stimulus-permeability coupling process in the sweat gland may be sensitive to the lowering of internal pH.

The cholinergic regulation of potassium (86Rb+) permeability in sweat glands isolated from patients with cystic fibrosis.

Sweat glands isolated from skin obtained from normal subjects and patients with cystic fibrosis (CF) were pre-loaded with 86Rb+ and superfused with a physiological salt solution and the rate of 86Rb+ efflux was measured as an indicator of cellular potassium permeability. Acetylcholine always evoked a permeability increase in the glands from control subjects and this response could be resolved into calcium-dependent and calcium-independent components. Sweat glands from CF patients did not show such consistent responses. In three individuals the glands were abnormally insensitive to acetylcholine but normal responsiveness was seen in a fourth case. It is proposed that CF can induce dysfunction of calcium-dependent control processes in sweat glands.

The effects of removing external sodium upon the control of potassium (86Rb+) permeability in the isolated human sweat gland.

The changes in cytoplasmic free calcium ([Ca2+]i) which occur in isolated human sweat glands during cholinergic stimulation have been studied indirectly by monitoring potassium permeability. The acetylcholine-evoked permeability increase normally consists of transient and sustained phases which are attributed to the mobilization of intracellular calcium stores and to calcium influx respectively. Such consistent responses to acetylcholine could not be obtained during superfusion with bicarbonate-free, HEPES-buffered solutions. The human sweat gland in vitro therefore appears to have a strict requirement for bicarbonate. The sustained component of the response was not affected by total removal of external sodium, suggesting that calcium influx does not occur via a sodium-dependent system. The transient component, however, was abolished when external sodium was replaced by N-methyl-D-glucammonium (NMDG+). It therefore appears that secretagogue-evoked mobilization of cytoplasmic calcium is dependent, in some way, upon external sodium. This dependence is not, however, absolute as the response was essentially normal when sodium was replaced by lithium.

Automated image segmentation and serial section reconstruction in microscopy.

A technique for automatic 3-D reconstruction of specifically stained features in televised serial histological sections has been developed using an image analyser. Images which included these features were individually converted to binary images, compiled, displayed to show the 3-D morphology and used to quantify the structure. The criteria necessary for producing valid reconstructions and the problems associated with the manipulation of images of fine detail, particularly those containing several thousand features, are illustrated by examples from skin.

Actions of bovine skin washings and sera on the motile zoospores of Dermatophilus congolensis.

Concentrated skin washings, even from vaccinated animals, failed to inhibit the motility of the infective zoospores of Dermatophilus congolensis, or to prevent them from germinating or infecting cattle; their constituent immunoglobulins did not attach to the flagella although IgA and IgG2 did bind to the cell bodies. It is concluded that the specific antibodies at the skin surface of ruminants are unlikely to have a role in zoospore immobilisation. Post vaccination sera rapidly immobilised and clumped the zoospores by means of a coat around the flagella, in which immunoglobulins, particularly IgM, were detected. IgM and IgG1 also attached to the cell bodies of the zoospores.

The control of potassium (86Rb+) efflux in the isolated human sweat gland.

Sweat glands, isolated from strips of human skin and pre-loaded with 86Rb+, a marker of potassium transport, were superfused with physiological saline and rate constants for 86Rb+ efflux calculated. The rate of efflux during superfusion with Ca2+-free saline was lower than that measured in the presence of calcium (2.56 mM). Acetylcholine increased the rate of 86Rb+ efflux and this response could be resolved into two components: an initial transient phase which was Ca2+-independent and a slowly declining Ca2+-dependent phase. Adrenaline only caused a Ca2+-dependent increase in efflux. It is suggested that the potassium permeability of the secretory cells increases during activity.

Effects of season and lower ambient temperature on the structure of the sweat glands in anhidrotic horses.

Histological studies of the sweat glands of anhidrotic horses in the Hong Kong summer and under conditions of reduced thermal stress, both natural and controlled, were undertaken to determine if glandular regeneration occurs. Clinical data were collected for comparison with the histological results in each instance. Horses were assigned to one of three categories on the basis of the resulting change in the number of thin glandular profiles in a cooler environment. Group 1, which was classed as normal, had a low initial value, which was maintained. Group 2, typical of mild and moderately affected animals, had a high initial value, which fell markedly after as little as six weeks in the cool environment. Animals in Group 3, classed as severely affected, had a high initial value which remained high even after prolonged exposure to the cool environment. Light microscopical examination of the sweat glands in the heat, and after six weeks in a cool environment, provided a means of predicting the degree of anhidrotic severity and the potential for recovery in a cool climate. This was superior to clinical observation, although a diagnostic test based on glandular function is still required.

Studies of the pathogenesis of orf virus infection in sheep.

Damage to the skin is essential for the establishment of orf virus infection and the development of typical lesions. However, analysis of the pathogenesis of experimental lesions induced by viral challenge of mildly abraded skin, indicated that the virus does not establish in the damaged epidermis, but replicates in the cells of an underlying replacement epidermal layer derived from the walls of the wool follicles. The skin reaction consists of a cellular response with necrosis and sloughing of the affected epidermis and underlying stratum papillare of the dermis. Healing is then completed by the formation of a third epidermis derived from the deeper portions of the wool follicles. Previous cutaneous infection did not prevent reintroduction of the disease, even on the same area of skin although the lesions were less severe and persisted for a shorter period.

Effects of stimulation on the ultrastructure and Na, K, Cl composition of the fundus of the rat plantar sweat gland.

Initial stimulation of the rat plantar sweat gland with pilocarpine caused a variable degree of distension of the apical membrane of the secretory cell. This appeared to be a process of filtration of secretory cell cytoplasm through the apical terminal web. Further stimulation resulted in luminal dilatation, cytoplasmic depletion, and morbidity of some cells. These morphological changes in the footpad gland, which thus can no longer be considered as eccrine, were accompanied by a fall in potassium and a rise in sodium concentration within the secretory cells. The mode of secretion induced by pharmacological stimulation was fundamentally the same as that in the glands of species responsive to thermal stimulation.

The effects of thermally-induced activity in vivo upon the ultrastructure and Na, K and Cl composition of the epithelial cells of sweat glands from patients with cystic fibrosis.

The secretory cells of the fundus of sweat glands from cystic fibrosis (CF) patients had higher Na and Cl contents and showed more granule depletion, cellular disruption and dilated intercellular canaliculi than normal. The cells of the coiled duct also had higher cytoplasmic levels of Na and Cl but were structurally normal. Thermal stimulation produced ultrastructural changes in the CF fundus comparable to normal, including further dilatation of the basolateral clefts, but did not induce the marked changes in the coiled duct which normally occur. The elevated Na and fall in K in the fundus and raised Na and Cl in the coiled duct upon activation, were not observed in the CF glands in which no significant changes were detected.

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.

Sequential production of specific antibodies in serum and at the skin surface of cattle following intradermal vaccination with Dermatophilus congolensis.

Studies of the temporal changes in specific antibody titres to D. congolensis in serum and washings from inoculated and uninoculated skin indicate that production of IgG1 and IgG2 antibody at the skin surface is a transudative process related to serum antibody concentration. Transport of IgM is likely to be based on a similar mechanism but that of IgA appears to depend on a local secretory process.

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.