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Biomedical subjects

S K Ahn

Publications and source records attributed to S K Ahn.

At least 19 recordsLinked to original sources
PubMed2001

Functional and structural changes of the epidermal barrier induced by various types of insults in hairless mice.

Acute barrier disruption, regardless of the method of induction, depletes the stratum corneum intercellular lipids and this stimulates a series of lipid/ DNA synthesis activities which lead to barrier recovery. After barrier disruption by tape stripping, occlusion with a water vapor-impermeable membrane inhibits barrier repair. In this study, we investigated the changes in the murine epidermis after barrier perturbation by tape stripping and three different types of surfactants (Emalex NP-12, ENP-12; sodium dodecyl sulfate, SDS; benzalkonium chloride, BKC). To examine the effect of an artificial barrier, we covered the animals with a water vapor-impermeable membrane for 3 days following barrier disruption and then exposed them to the air for 2 days. The histological findings after occlusion or air exposure were similar. However, after air exposure for 2 days, the thickness of the epidermis including the stratum corneum and the stratum granulosum layers decreased to about half that of the epidermis after occlusion. Ultrastructural examination revealed obvious distortion of the lamellar bilayers within the stratum corneum interstices immediately after barrier disruption. After 3 days of occlusion, extensive disorganization was evident in the intercellular domain of the stratum corneum, whereas 2 days after removal of the occlusion, the normal basic unit structure of the lamellar bilayers had partially reappeared. Our findings provide evidence that the kinetic pattern of barrier repair and the morphological changes are similar after occlusion following barrier disruption regardless of the mechanism of disruption.

Animals↗
PubMed2001

Generation of free fatty acids from phospholipids regulates stratum corneum acidification and integrity.

There is evidence that the "acid mantle" of the stratum corneum is important for both permeability barrier formation and cutaneous antimicrobial defense. The origin of the acidic pH of the stratum corneum remains conjectural, however. Both passive (e.g., eccrine/sebaceous secretions, proteolytic) and active (e.g., proton pumps) mechanisms have been proposed. We assessed here whether the free fatty acid pool, which is derived from phospholipase-mediated hydrolysis of phospholipids during cornification, contributes to stratum corneum acidification and function. Topical applications of two chemically unrelated secretory phospholipase sPLA2 inhibitors, bromphenacylbromide and 1-hexadecyl-3-trifluoroethylglycero-sn-2-phosphomethanol, for 3 d produced an increase in the pH of murine skin surface that was paralleled not only by a permeability barrier abnormality but also altered stratum corneum integrity (number of strippings required to break the barrier) and decreased stratum corneum cohesion (protein weight removed per stripping). Not only stratum corneum pH but also all of the functional abnormalities normalized when either palmitic, stearic, or linoleic acids were coapplied with the inhibitors. Moreover, exposure of intact murine stratum corneum to a neutral pH for as little as 3 h produced comparable abnormalities in stratum corneum integrity and cohesion, and further amplified the inhibitor-induced functional alterations. Furthermore, short-term applications of an acidic pH buffer to inhibitor-treated skin also reversed the abnormalities in stratum corneum integrity and cohesion, despite the ongoing decrease in free fatty acid levels. Finally, the secretory-phospholipase-inhibitor-induced alterations in integrity/cohesion were in accordance with premature dissolution of desmosomes, demonstrated both by electron microscopy and by reduced desmoglein 1 levels in the stratum corneum (shown by immunofluorescence staining and visualized by confocal microscopy). Together, these results demonstrate: (i) the importance of phospholipid-to-free-fatty-acid processing for normal stratum corneum acidification; and (ii) the potentially important role of this pathway not only for barrier homeostasis but also for the dual functions of stratum corneum integrity and cohesion.

Acetophenones↗
PubMed2001

The effects of topical alpha-hydroxyacids on the normal skin barrier of hairless mice.

BACKGROUND: alpha-hydroxyacids (AHA), such as glycolic acid and lactic acid, have recently been used in cosmetic and dermatological formulations. However, the mechanisms of action of these substances have not been well documented. OBJECTIVES: This study was done to investigate the effects of AHA on the skin barrier of hairless mice and to clarify the contribution of AHA to the formation and secretion of the lamellar bodies (LB), which are known to be the critical structure for barrier function in the epidermis. METHODS: 5% Lactic acid and 5% glycolic acid were applied to normal skin of the mice daily for 14 days. RESULTS: Changes in transepidermal water loss (TEWL), capacitance and electron microscopic findings of the epidermis of hairless mice were compared with those in which only the vehicle was applied. CONCLUSIONS: There were no significant differences in TEWL, capacitance or epidermal thickness between the epidermis of the mice to which AHA or vehicle only had been applied. On electron micrographs, the normal epidermis to which AHA had been applied showed an increase in the number and secretion of LB and a decrease in the number of stratum corneum (SC) layers in comparison with the epidermis to which the vehicle only had been applied. The lipid layers of the SC intercellular spaces and calcium gradient in both the epidermis with application of AHA and that with vehicle only were normal. These results suggest that AHA, in low concentration (5%), may improve the skin barrier in hairless mice by inducing enhanced desquamation, and by increasing the number and secretion of LB without increasing TEWL.

Animals↗
PubMed2001

Basis of occlusive therapy in psoriasis: correcting defects in permeability barrier and calcium gradient.

BACKGROUND: Although occlusive dressings have great potential in the management of psoriasis vulgaris, the therapeutic mechanism is not completely understood. Occlusion artificially restores and corrects the defective barrier in psoriasis plaques. Additionally, occlusion is know to normalize the epidermal calcium gradients in hyperproliferative murine skin models. METHODS: To investigate the basis of the therapeutic effect of occlusion on psoriatic plaques, we investigated the ultrastructural morphology of intercorneocyte lipid layers, lamellar bodies, and calcium gradient in chronic plaque-type psoriasis after occlusion with a water vapor-impermeable membrane. The specimens were processed for electron microscopy using: (i) ruthenium tetroxide postfixation; and (ii) ion-capture cytochemistry for calcium localization. RESULTS: Occlusion for 7 days resulted in a nearly mature pattern of intercellular multilamellar structures, re-establishment of the near-normal epidermal calcium gradient, and disappearance of calcium precipitates from the stratum corneum interstices. CONCLUSIONS: The normalization of the permeability barrier and epidermal calcium gradient may play important roles in the therapeutic effects of occlusive dressings in chronic plaque-type psoriasis.

Calcium↗
PubMed2001

The effects of famciclovir and epidural block in the treatment of herpes zoster.

In our previous study, we concluded that an epidural blockade combined with intravenous acyclovir is very effective in treating the acute pain in herpes zoster and postherpetic neuralgia. We evaluated the efficacy of oral famciclovir and epidural blockade on the pain of herpes zoster, compared to acyclovir administered intravenously and epidural blockade. For this purpose, we examined a new group treated with famciclovir and epidural blockade to compare with the group treated with acyclovir and epidural blockade in our previously study. The changes in the intensity of pain, the number of days required for relief of pain, and the total duration of pain were checked. We compared the days required for relief of pain (DRP) and the total duration of pain (TDP) of this group with those of the previous studied group treated with acyclovir and epidural blockade. DRP was significantly less, but TDP was similar. DRP and TDP were significantly lower, if the patients were treated within 7 days of symptom onset. The patients had a shorter DRP regardless of pain type than the previously studied group treated with acycolvir and epidural blockade. For the severe and moderate pain grades, there was a shorter DRP from 100 to 10. TDP was not significantly different for the groups regardless of pain type or grade. We believe that famciclovir and epidural blockade are very effective in treating the pain of herpes zoster, with a view to shortening the period of acute pain, providing similar effects on the prevention of postherpetic neuralgia, and being convenient to administer, compared to intravenous acyclovir and epidural blockade in our previous study.

2-Aminopurine↗
PubMed2001

Studies on the changes of c-fos protein in spinal cord and neurotransmitter in dorsal root ganglion of the rat with an experimental peripheral neuropathy.

Animal models for human chronic pain syndromes have been developed and widely used for pain research. One of these neuropathic pain models by Kim and Chung (1992) has many advantages for operation and pain elicitation. In this neuropathic model we have examined the c-fos protein, substance P, CGRP immunoreactivity in dorsal root ganglia and dorsal horn. 50 Sprague-Dawley rats were used for this study. L5 and L6 spinal nerves were ligated tightly to produce the neuropathic pain model. After 2, 4, 8, 16, and 24 hours and 1 week of surgery, rats were anesthetized and sacrificed by perfusion. After confirmation of the roots transected by the surgery, the L5 and L6 dorsal root ganglions and spinal cord were removed and processed for immunohistochemistry. All tissue sections were immunohistochemically stained for substance P, CGRP and c-fos using the peroxidase-antiperoxidase (PAP) method. The number of immunostained substance P and CGRP dorsal root ganglion cells and c-fos immunoreactive dorsal horn cells were counted and analyzed statistically with Mann-Whitney U test. The results are as follows. The number of c-fos protein immunoreactive neurons in the superficial layer of dorsal horn were increased markedly 2 hours after operation, and gradually decreased to normal level 1 week after operation. The number of c-fos protein immunoreactive neurons in the deep layer of the dorsal horn gradually increased to a peak 24 hours after operation, then decreased to the normal level 1 week after operation. The number of substance P and CGRP immunoreactive L5 and L6 dorsal root ganglion neurons were decreased markedly 1 week after the pain model operation. In conclusion, after neuropathic pain model operation, c-fos proteins were immediately expressed in the superficial layer of spinal dorsal horn, thereafter c-fos proteins in the deep layer of spinal dorsal horn were expressed. CGRP and substance P immunoreactive neurons in DRG were decreased markedly 1 week after neuropathic pain model operation. These decrements do not coincide with the other chronic pain models, which show great increases in these pain transmitting substances. Therefore, the relationship between pain and c-fos, SP and CGRP should be investigated further.

Animals↗
PubMed2001

Complications of eyelash and eyebrow tattooing: reports of 2 cases of pigment fanning.

Eyelash and eyebrow tattooing are commonly performed procedures that have a very low rate of reported complications. We describe one case of infraorbital pigmentation after eyelash tattooing and another of periorbital pigmentation after eyebrow tattooing. Although most complications related to eyelash and eyebrow tattooing, including pigment fanning, have been reported by ophthalmologists, pigment fanning is also of concern to dermatologists.

Adult↗
PubMed2000

Tuberculous cellulitis.

We report a case of cutaneous tuberculosis presenting as cellulitis. The patient was a 63-year-old Korean woman who also had diabetes mellitus and a 20-year-history of oral corticosteroid medication prescribed for arthralgia. In addition, she had had pulmonary tuberculosis 20-year previously for which she received systemic treatment for 1 year. Her clinical cellulitis failed to respond to antibiotic therapy. Subsequent investigations, using histopathology and polymerase chain reaction, established an alternative diagnosis of cutaneous tuberculosis. The skin eruption cleared after treatment with isoniazid, rifampicin, ethambutol and pyrazinamide. This case represents a most unusual presentation of tuberculosis in the skin. The atypical features may reflect the patient's general medical state.

Antitubercular Agents↗
PubMed2000

Structural and functional effects of oleic acid and iontophoresis on hairless mouse stratum corneum.

The aim of this study was to assess the effects of chemical and electrical modes of percutaneous penetration enhancement on the intercellular lipid lamellae of the stratum corneum. Hairless mice were treated with either oleic acid/propylene glycol and iontophoresis separately or together. Permeability barrier function was evaluated by measuring transepidermal water loss and correlated with the structure of stratum corneum intercellular lamellae, as evaluated by electron microscopy, using ruthenium tetroxide postfixation. Transepidermal water loss levels did not change following 1 h iontophoresis alone. In contrast, topical applications of 0.3 M oleic acid in propylene glycol for 1 h increased transepidermal water loss significantly. Moreover, the combined use of iontophoresis plus 0.3 M oleic acid for 1 h further increased transepidermal water loss at equivalent time points. Ultrastructural observations demonstrated both marked disorganization of the intercellular lipid lamellae, as well as the presence of distended lacunae within the stratum corneum in oleic acid/propylene glycol plus or minus iontophoresis-treated stratum corneum. This study provides direct evidence that the oleic acid/propylene glycol system can disrupt the stratum corneum lipid lamellar structures, and that coapplications of oleic acid with iontophoresis further enhance the effects of oleic acid. The synergy between chemical and physical enhancement may afford a new approach to promote transdermal drug delivery.

Animals↗
PubMed2000

Apocrine poroma with sebaceous differentiation.

Poromas have been classified as eccrine neoplasms, but several recent reports of poroid tumors with sebaceous, follicular, and apocrine differentiation have challenged this concept. We report a case of apocrine poroma with sebaceous differentiation. A 69-year-old man presented with an asymptomatic elevated erythematous plaque. Histopathology revealed cellular nests composed of cuboidal poroid cells and sebocytes. The nests varied in size and were entirely intraepidermally arranged in a growth pattern similar to that of hidroacanthoma simplex. Given the common embryologic origin of folliculosebaceous and apocrine units, we believe that this lesion represents an apocrine poroma with sebaceous differentiation.

Acrospiroma↗
PubMed1999

The effects of epidural blockade on the acute pain in herpes zoster.

OBJECTIVE: To evaluate the relief of acute pain and possible preventive effects on postherpetic neuralgia through the use of an epidural blockade in the acute stage of herpes zoster. DESIGN: Prospective, nonrandomized, comparative clinical trial. SETTING: A dermatologic clinic in a university hospital. PATIENTS: Sixty-five consecutive patients with pain due to acute herpes zoster were treated for a 7-day hospitalization period from July 1, 1996, through June 30, 1997. INTERVENTION: The consecutive patients were divided into 2 groups. Group A consisted of 30 patients who were seen from July 1, 1996, through December 31, 1996, and who were treated with intravenous acyclovir (5 mg/kg) for 7 days. Group B consisted of 35 patients who were seen from January 1, 1997, through June 30, 1997, and who were treated with intravenous acyclovir (5 mg/kg) and an epidural blockade for 7 days. The changes in the intensity of pain and the total duration of pain in both groups were assessed for 12 to 18 months. MAIN OUTCOME MEASURES: The number of days required for relief of pain and the total duration of pain. RESULTS: The mean +/- SD number of days required for relief of pain, which was rated on a scale of 100 (worst pain) to 0 (no pain), was significantly fewer in group B than in group A: it took 2.6 +/- 1.1 days to go from 100 to 50 on the relief-of-pain scale in group B, but 3.8 +/- 1.1 days in group A (P = .03), and 12.5 +/- 6.4 days to go from 100 to 10 in group B, but 20.1 +/- 14.6 days in group A (P = .04). The duration of late residual pain was significantly shorter in group B (5.9 +/- 5.8 days) than in group A (11.9 +/- 7.5 days) (P = .03). The total duration of pain was also significantly shorter in group B (18.5 +/- 9.3 days) than in group A (31.6 +/- 17.6 days) (P = .04). CONCLUSIONS: We believe that an epidural blockade combined with an antiviral agent is a very effective treatment modality for the pain of acute herpes zoster, and we recommend its use for the prevention of postherpetic neuralgia, with a view to shortening the total duration of pain, especially late residual pain.

Acute Disease↗
PubMed1999

Pincer nail deformity and pseudo-Kaposi's sarcoma: complications of an artificial arteriovenous fistula for haemodialysis.

Pseudo-Kaposi's sarcoma which develops due to arteriovenous fistulae for haemodialysis is relatively well known. In contrast, nail changes associated with pseudo-Kaposi's sarcoma or venous hypertension are rare. We report a novel case of pincer nail deformity associated with pseudo-Kaposi's sarcoma and venous hypertension, complications of an arteriovenous fistula for haemodialysis, and review eight similar cases reported in the literature. Most of the subjects presented with similar findings, having circulatory disturbance due to an arteriovenous fistula and/or increased venous pressure, and swelling, discoloration and papules/nodules of the skin distal to the shunt. Of the nine patients, three had overcurvature of the nails, in which the lateral edge of the nail pressed deeply into the lateral nail fold. Pincer nail deformity associated with pseudo-Kaposi's sarcoma after placement of an arteriovenous fistula may be relatively common and should be recognized as a specific sign of circulatory disturbance due to the arteriovenous fistula.

Arteriovenous Shunt, Surgical↗
PubMed1999

Nurse's cap alopecia.

BACKGROUND: Traction alopecia associated with the nurse's cap is a relatively common form of occupational hair loss. METHODS: We examined 199 healthy South Korean nurses to assess the clinical and pathologic characteristics of traction alopecia caused by prolonged traction exerted at the point of attachment of the nurse's cap. RESULTS: Seven nurses (3.5% of 199) had hair loss at the pin site used to secure the nurse's cap. The lesions were exclusively localized on the parieto-occipital scalp. Histopathologic findings revealed characteristic cicatricial changes which showed a marked decrease in the number of hair follicles without inflammation. CONCLUSIONS: Nurse's cap alopecia is not an uncommon occupational alopecia, and appears to be a distinct clinical entity which should be distinguished from other forms of patchy alopecia.

Adult↗
PubMed1999

The changes of epidermal calcium gradient and transitional cells after prolonged occlusion following tape stripping in the murine epidermis.

Disruption of the epidermal permeability barrier causes an immediate loss of the calcium gradient, and barrier recovery is parallel with the restoration of the calcium gradient in the epidermis. Artificial restoration of the barrier function by occlusion with a water vapor-impermeable membrane abrogate the expected increase in lipid synthesis and retard the barrier recovery, as well as block the normalization of the epidermal calcium gradient. To clarify the long-term effects of occlusion after acute barrier perturbation, we studied the calcium distribution and epidermal keratinocytes response after occlusion with a water vapor-impermeable membrane immediately following tape stripping in the murine epidermis. Acute barrier disruption caused an immediate depletion of most calcium ions in the upper epidermis, obliterating the normal calcium gradient. When the skin barrier function was artificially corrected by occlusion, the return of calcium ions to the epidermis was blocked. After 2 h of air exposure or occlusion, the density of epidermal calcium precipitates remained negligible. The transitional cell layers appeared with occlusion, but not or negligibly with air exposure. By 6 h though, calcium precipitates could be seen, the density of the calcium precipitates with occlusion was more sparse than with air exposure. With the air exposure, the thickness of the stratum corneum had normalized and the calcium gradient nearly recovered to normal after 24 h. The longer the occlusion period, the greater was the increase of transitional cells. By 60 h of occlusion, the thickness of the stratum corneum had increased and the transitional cell layers had disappeared, in parallel with the calcium gradient which was almost normalized. These results show that prolonged occlusion of tape-stripped epidermis induced transitional cells and delayed the restoration of the epidermal calcium gradient, the stratum corneum was then restored, transitional cells having disappeared, in parallel with normalization of the epidermal calcium gradient.

Animals↗