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Biomedical subjects

Sewon Kang

Publications and source records attributed to Sewon Kang.

At least 37 records · Page 2Linked to original sources
PubMed2004

Treatment of acne vulgaris with a pulsed dye laser: a randomized controlled trial.

CONTEXT: The high prevalence of acne vulgaris and its significant morbidity underscore the need for convenient, low-risk, and efficacious therapy. Treatment with various lasers has been reported to improve acne. OBJECTIVE: To evaluate the clinical efficacy of pulsed dye laser therapy in the treatment of acne. DESIGN, SETTING, AND PATIENTS: Randomized, single-blind, controlled, split-face clinical trial of a volunteer sample of 40 patients aged 13 years or older with facial acne conducted at an academic referral center from August 2002 to September 2003. INTERVENTION: One or 2 nonpurpuric pulsed dye laser treatments to half of the face (fluence of 3 J/cm2), serial blinded clinical assessments (lesion counts), and grading of acne severity using standardized bilateral serial photographs. MAIN OUTCOME MEASURES: Comparison of the changes in lesion counts from baseline to 12 weeks between treated and untreated sides of the face and changes in photographic evidence of acne severity as graded by a panel of dermatologists blinded to treatment assignment. RESULTS: After 12 weeks, using intent-to-treat analysis with last observation carried forward, there were no significant differences between laser-treated and untreated skin for changes in mean papule counts (-4.2 vs -2.2; P =.08), mean pustule counts (0 vs -1.0; P =.12), or mean comedone counts (2.9 vs 1.6; P =.63). Grading of serial photographs confirmed the clinical assessments, showing no significant mean (SE) differences in Leeds scores (range, 1-12) for treated skin (3.98 [0.32] at baseline and 3.94 [0.27] at week 12) compared with untreated skin (3.83 [0.32] at baseline and 3.79 [0.28] at week 12) (P>.99). CONCLUSIONS: In this study, the nonpurpuric pulsed dye laser therapy did not result in significant improvement of facial acne. More research is needed before this laser therapy may be recommended as an acne treatment.

Acne Vulgaris↗
PubMed2004

Connective tissue remodeling induced by carbon dioxide laser resurfacing of photodamaged human skin.

OBJECTIVE: To quantitatively examine the dynamics of molecular alterations involved in dermal remodeling after carbon dioxide (CO(2)) laser resurfacing of photodamaged human skin. DESIGN: Serial in vivo biochemical analyses after laser therapy. SETTING: Academic referral center, Department of Dermatology, University of Michigan, Ann Arbor. Subjects Volunteer sample of 28 adults, 48 to 76 years old, with clinically evident photodamage of the forearms. Intervention Focal CO(2) laser resurfacing of photodamaged forearms and serial biopsies at baseline and various times after treatment. MAIN OUTCOME MEASURES: Reverse transcriptase real-time polymerase chain reaction technology and immunohistochemistry were used to assess levels of type I and type III procollagens; matrix metalloproteinases (MMPs) 1, 3, 9, and 13; tropoelastin; fibrillin; primary cytokines interleukin 1beta and tumor necrosis factor alpha; and profibrotic cytokine transforming growth factor beta1. RESULTS: Production of type I procollagen and type III procollagen messenger RNA peaked at 7.5 and 8.9 times baseline levels, respectively, 21 days after treatment and remained elevated for at least 6 months. Increases in messenger RNA levels of several cytokines (interleukin 1beta, tumor necrosis factor alpha, and transforming growth factor beta1) preceded and/or accompanied changes in collagen levels. Marked increases in messenger RNA levels of MMP-1 (39 130-fold), MMP-3 (1041-fold), MMP-9 (75-fold), and MMP-13 (767-fold) were noted. Levels of fibrillin and tropoelastin rose in a delayed fashion several weeks after treatment. CONCLUSIONS: The biochemical changes seen after CO(2) laser resurfacing proceed through a well-organized and highly reproducible wound healing response that results in marked alterations in dermal structure. These quantitative changes may serve as a means for comparison as other therapeutic modalities meant to improve the appearance of photodamaged skin are evaluated.

Aged↗
PubMed2004

Effect of carbon dioxide laser resurfacing on epidermal p53 immunostaining in photodamaged skin.

OBJECTIVE: To quantitatively examine changes in p53 tumor suppressor gene immunostaining after carbon dioxide (CO(2)) laser resurfacing of photodamaged skin to assess the potential value of this treatment in reducing the risk of progression to cutaneous carcinoma. DESIGN: Serial in vivo immunohistochemical analyses after laser therapy. SETTING: Academic referral center, Department of Dermatology, University of Michigan, Ann Arbor. OTHER PARTICIPANTS: Volunteer sample of 11 adults, 51 to 76 years old, with clinically evident photodamage of the forearms. INTERVENTION: Focal CO(2) laser resurfacing of photodamaged forearms and serial biopsies at baseline, 3 weeks, and 6 months after treatment. MAIN OUTCOME MEASURES: Because keratinocytes with mutations in p53 or altered p53 expression stain via immunohistochemical techniques, image analysis of immunohistochemically stained sections was used to quantify p53 expression. RESULTS: Positive immunostaining for p53 in the interfollicular epidermis was noted in 8 of 11 subjects at baseline, with an average staining density of 250 cells/mm(2). Average staining decreased to 3 cells/mm(2) 3 weeks after treatment. This decrease was sustained at 5 cells/mm(2) 6 months after resurfacing. CONCLUSIONS: There was a consistent decrease in p53 immunostaining in the interfollicular epidermis lasting for at least 6 moths after CO(2) laser resurfacing of photodamaged skin. Since p53 mutation or overexpression is observed in a majority of cases of cutaneous carcinoma, the posttreatment repopulation of the epidermis with p53-negative keratinocytes should theoretically decrease the risk of malignant progression. Further study of laser resurfacing as a prophylactic procedure in patients at high risk for skin cancer development appears warranted.

Administration, Topical↗
PubMed2004

Evaluation of safety and clinical activity of multiple doses of the anti-CD80 monoclonal antibody, galiximab, in patients with moderate to severe plaque psoriasis.

BACKGROUND: Reduction in lesional, activated T cells induces improvement in psoriatic plaques. Galiximab (IDEC-114), an IgG(1) anti-CD80 antibody, binds to CD80, a costimulatory molecule involved in T-cell activation. OBJECTIVE: A Phase I/II, multidose, multischedule, dose-finding study of galiximab to evaluate safety, pharmacokinetics, and clinical activity was conducted in 35 patients with moderate to severe plaque psoriasis. METHODS: Seven cohorts of five patients received galiximab intravenously on three different schedules at different dose levels. RESULTS: Adverse events (AEs) commonly occurred as mild and self-limiting. Improvements were observed in most cohorts without evidence of a dose response in Psoriasis Area and Severity Index (50% or greater reduction in PASI score in 40% of patients), Physician's Global Psoriasis Assessment (PGA rating of Good or above in 57% of patients), and Psoriasis Severity Scale (PSS, baseline mean of 7.6 decreased by Study Day 127 to 5.0). An association was observed between reduction in CD3(+) cell count in histologic studies and reduction in PASI score. No antibodies to galiximab were detected. CONCLUSION: Galiximab appears to be safe and well tolerated with preliminary evidence of clinical and histologic response.

Adult↗
PubMed2004

A systemic type I 5 alpha-reductase inhibitor is ineffective in the treatment of acne vulgaris.

Excessive sebum production is a central aspect of the pathophysiology of acne vulgaris. Sebaceous gland function is under androgen control and it is hypothesized that dihydrotestosterone is formed by the action of 5 alpha-reductase. Type I is the controlling isoenzyme. This study describes a 3-month, multicenter, randomized, placebo-controlled clinical trial with a potent, selective inhibitor of type I 5 alpha-reductase used alone and in combination with systemic minocycline. Inhibition of type I 5 alpha-reductase was not associated with clinical improvement of acne when used alone and did not enhance the clinical benefit of systemic minocycline. These results indicate the need for further work at the molecular level to better understand the action of androgens on sebaceous gland function.

Acne Vulgaris↗
PubMed2004

Effect of a single course of isotretinoin therapy on bone mineral density in adolescent patients with severe, recalcitrant, nodular acne.

BACKGROUND: Adverse changes in bone have been reported for patients undergoing high-dose, long-term (several years) isotretinoin therapy for disorders of cornification. The effect of short-term (4-5 months) therapy at the lower dose recommended for acne on bone development in younger, growing adolescent (12-17 years) patients has not been well studied. OBJECTIVE: The purpose of the study was to evaluate the effect of a standard, single course of isotretinoin (Accutane) therapy on bone mineral density (BMD) of the lumbar spine and hip in adolescents ages 12 to 17 years with severe, recalcitrant, nodular acne. METHODS: In this open-label, multicenter study, 217 adolescents (81 girls) with severe, recalcitrant, nodular acne were enrolled and treated with isotretinoin twice daily with food at the recommended total dose of approximately 1 mg/kg for 16 to 20 weeks. BMD in the lumbar spine and hip was measured at baseline and at the end of therapy by dual energy radiograph absorptiometry. RESULTS: There was no clinically significant mean change in BMD measured at the lumbar spine (+1.4%, range: -4.9% to +12.3%) or total hip (-0.26%, range: -11.3% to +15.0%). Hyperostosis was not observed in any patient. Typical efficacy expected in the treatment of acne was observed. CONCLUSIONS: A 16- to 20-week course of isotretinoin treatment at the recommended dose for severe acne has no clinically significant effect on lumbar spine and total hip BMD in the adolescent (12-17 years) population.

Acne Vulgaris↗
PubMed2004

Tretinoin treatment before carbon-dioxide laser resurfacing: a clinical and biochemical analysis.

BACKGROUND: Tretinoin is often prescribed before laser resurfacing in an attempt to enhance results. OBJECTIVE: We sought to assess the clinical and biochemical effects of preoperative tretinoin use before laser resurfacing. METHODS: Patients were randomized to apply tretinoin to one forearm and placebo to the other for 3 weeks. Patients' photodamaged forearms were focally treated by carbon-dioxide laser resurfacing. Biopsy specimens were obtained at baseline and various times posttreatment. Real-time polymerase chain reaction technology was used to quantify messenger RNA levels of types I and III procollagen and matrix metalloproteinases-1, 3, and 9. Wounds were assessed for degree of re-epithelialization using a computer graphics-generated template. A colorimeter was used to quantify postoperative erythema. RESULTS: No substantial differences in either biochemical markers or clinical end points were identified between tretinoin and placebo pretreated forearms. CONCLUSIONS: We found no evidence of enhanced collagen formation, accelerated re-epithelialization, or quicker resolution of postoperative erythema with tretinoin pretreatment before laser resurfacing.

Administration, Cutaneous↗
PubMed2004

Solar ultraviolet irradiation reduces collagen in photoaged human skin by blocking transforming growth factor-beta type II receptor/Smad signaling.

Ultraviolet (UV) irradiation from the sun reduces production of type I procollagen (COLI), the major structural protein in human skin. This reduction is a key feature of the pathophysiology of premature skin aging (photoaging). Photoaging is the most common form of skin damage and is associated with skin carcinoma. TGF-beta/Smad pathway is the major regulator of type I procollagen synthesis in human skin. We have previously reported that UV irradiation impairs transforming growth factor-beta (TGF-beta)/Smad signaling in mink lung epithelial cells. We have investigated the mechanism of UV irradiation impairment of the TGF-beta/Smad pathway and the impact of this impairment on type I procollagen production in human skin fibroblasts, the major collagen-producing cells in skin. We report here that UV irradiation impairs TGF-beta/Smad pathway in human skin by down-regulation of TGF-beta type II receptor (TbetaRII). This loss of TbetaRII occurs within 8 hours after UV irradiation and precedes down-regulation of type I procollagen expression in human skin in vivo. In human skin fibroblasts, UV-induced TbetaRII down-regulation is mediated by transcriptional repression and results in 90% reduction of specific, cell-surface binding of TGF-beta. This loss of TbetaRII prevents downstream activation of Smad2/3 by TGF-beta, thereby reducing expression of type I procollagen. Preventing loss of TbetaRII by overexpression protects against UV inhibition of type I procollagen gene expression in human skin fibroblasts. UV-induced down-regulation of TbetaRII, with attendant reduction of type I procollagen production, is a critical molecular mechanism in the pathophysiology of photoaging.

Collagen Type I↗
PubMed2004

Tazarotene 0.1% cream versus tretinoin 0.05% emollient cream in the treatment of photodamaged facial skin: a multicenter, double-blind, randomized, parallel-group study.

OBJECTIVES: To compare the efficacy and tolerability of tazarotene 0.1% cream and tretinoin 0.05% emollient cream in the treatment of photodamaged facial skin. METHODS: Subjects were eligible to enroll in this multicenter, double-blind, randomized, parallel-group study if they had at least mild levels of facial fine wrinkling and mottled hyperpigmentation, and at least moderate levels of one of these. Subjects were randomly assigned to apply either tazarotene cream or tretinoin emollient cream to their faces once each evening for 24 weeks. RESULTS: A total of 173 subjects were enrolled, of whom 157 completed. All significant between-group differences in efficacy measures were in favor of tazarotene - for fine wrinkling at the study endpoint and, at earlier timepoints, for treatment success (> or =50% global improvement), and the overall integrated assessment of photodamage, mottled hyperpigmentation, and coarse wrinkling. Both products were comparable in terms of cosmetic acceptability and tolerability except that tazarotene was associated with a transiently higher incidence of a burning sensation on the skin (in the first week of treatment but not thereafter). CONCLUSIONS: Tazarotene 0.1% cream can offer superior efficacy over tretinoin 0.05% emollient cream in the treatment of facial photodamage, particularly with respect to the speed of improvement.

Administration, Topical↗
PubMed2004

Reduced fibroblast interaction with intact collagen as a mechanism for depressed collagen synthesis in photodamaged skin.

This report provides evidence from a number of different approaches (i.e., comparison of cell shape in 1-microm sections of photodamaged versus healthy skin at the light microscopic level; comparison of cell shape and apposition to collagen fibrils in ultrathin sections of the same tissues examined by transmission electron microscopy, and fluorescence staining for adhesion site protein expression and actin filament architecture in frozen tissue sections) that dermal cells in healthy skin are attached to collagen fibrils over a large part of the cell border, have a flattened/spread (two-dimensional) appearance and have abundant actin in their cytoplasm. In contrast, cells in photodamaged skin are often in contact with fragmented collagen or amorphous debris rather than intact collagen, have a collapsed/elongated shape, and have a lower amount of actin. Collagen synthesis is reduced in severely photodamaged skin relative to collagen synthesis in corresponding sun-protected skin (N Engl J Med 329:530, 1993). We hypothesize that fibroblasts in severely damaged skin have less interaction with intact collagen and as a result experience a reduction in mechanical tension. Decreased collagen synthesis is (presumed to be) the result.

Actin Cytoskeleton↗
PubMed2003

A randomized trial of etanercept as monotherapy for psoriasis.

OBJECTIVE: To determine safety and efficacy of monotherapy with etanercept. DESIGN: Randomized, double-blind, placebo-controlled, multicenter study. SETTING: Outpatient, ambulatory; private practice and university dermatology research centers. PATIENTS: Patients aged at least 18 years, with plaque psoriasis involving 10% or more of body surface area; 148 were screened and 112 were randomly assigned to treatment groups and received study drug. INTERVENTIONS: Patients received placebo or etanercept, 25 mg, subcutaneously twice a week for 24 weeks. Other psoriasis therapies were limited during the study. MAIN OUTCOME MEASURES: Safety measurements included tracking of adverse events and laboratory values. Efficacy was evaluated using the Psoriasis Area and Severity Index (PASI); the primary end point was a 75% improvement in PASI. Other efficacy measurements included patient and physician global assessments and quality-of-life measures. RESULTS: After 12 weeks of treatment, 17 (30%) of the 57 etanercept-treated patients and 1 (2%) of the 55 placebo-treated patients had achieved PASI 75%, and after 24 weeks, 32 (56%) of etanercept-treated patients and 3 (5%) of placebo-treated patients had reached this level (P<.001 for both time points). By 24 weeks, psoriasis was clear or minimal by physician's global assessment in more than 50% of patients who received etanercept. Treatment failure (PASI response <50) occurred in 23% of patients at week 24. All other measures confirmed the efficacy of etanercept. Adverse events were similar among etanercept and placebo groups. CONCLUSION: Etanercept monotherapy provided significant benefit to patients with psoriasis and had a favorable safety profile.

Adolescent↗
PubMed2003

Topical N-acetyl cysteine and genistein prevent ultraviolet-light-induced signaling that leads to photoaging in human skin in vivo.

Human skin is exposed to solar ultraviolet radiation. Ultraviolet radiation damages human skin and results in an old and wrinkled appearance, called photoaging. We have previously reported that molecular mechanisms by which ultraviolet light causes photoaging involve activation of growth factor and cytokine receptors in keratinocytes and dermal cells. They lead to downstream signal transduction through activation of mitogen-activated protein kinase (extracellular signal-regulated kinase, c-jun N-terminal protein kinase, and p38) pathways. These signaling pathways converge in the nucleus of cells to form an activated complex of transcription factor activator protein 1 (cFos/cJun), which induces matrix metalloproteinases that degrade skin connective tissue. In addition to cell surface receptor activation, generation of reactive oxygen species by ultraviolet radiation is believed to be critical in triggering mitogen-activated protein kinase pathways. We investigated the ability of (i) ultraviolet irradiation to generate reactive oxygen species in human skin in vivo; and (ii) genistein, which possesses both tyrosine kinase inhibitory and antioxidant activities, and n-acetyl cysteine, which can be converted into the endogenous antioxidant glutathione, to impair responses to ultraviolet light that eventuate in photoaging in human skin in vivo. Ultraviolet irradiation caused a rapid and significant increase in hydrogen peroxide levels in human skin in vivo. Pretreatment of human skin with genistein inhibited ultraviolet-induced epidermal growth factor receptor tyrosine kinase activity, whereas n-acetyl cysteine did not. Genistein inhibited ultraviolet induction of both extracellular signal-regulated kinase and cJun N-terminal protein kinase activities. n-Acetyl cysteine inhibited extracellular signal-regulated kinase but not cJun N-terminal protein kinase activation. Both genistein and n-acetyl cysteine prevented ultraviolet induction of cJun protein. Consistent with this, genistein and n-acetyl cysteine blocked ultraviolet induction of cJun-driven enzyme, collagenase. Neither genistein nor n-acetyl cysteine acted as sunscreens as they had no effect on ultraviolet-induced erythema. These data indicate that compounds similar to genistein and n-acetyl cysteine, which possess tyrosine kinase inhibitory and/or antioxidant activities, may prevent photoaging.

Acetylcysteine↗
PubMed2003

Collagen degradation in aged/photodamaged skin in vivo and after exposure to matrix metalloproteinase-1 in vitro.

Biochemical and ultrastructural approaches were used to assess collagen changes in photodamaged skin. Extensive collagen fragmentation, clumping of the fragmented collagen, and interaction of fibroblasts with the damaged matrix were observed. Similar, though less extensive, collagen damage was also observed in sun-protected skin-individuals aged 80 y or older (naturally aged skin). In comparison, sun-protected skin from young individuals (18-29 y of age) demonstrated little damage. A uniform distribution of collagen fibrils was seen. Interstitial fibroblasts were embedded in the collagen matrix and in close apposition with intact collagen fibrils. In additional studies, three-dimensional lattices of type I collagen were exposed in vitro to matrix metalloproteinase-1 (interstitial collagenase), and examined for biochemical and ultrastructural alterations. Under conditions in which enzyme treatment produced fragmentation in 30-40% of the collagen molecules, the lattices demonstrated collagen fragmentation and clumping of the damaged matrix. Recent studies have demonstrated a loss of procollagen production by fibroblasts in contact with collagen fragments in vitro. This study demonstrates similar changes in collagen structure in vivo in aged and photodamaged skin. We suggest that collagen fragmentation in vivo could underlie the loss of collagen synthesis in photodamaged skin and, to a lesser extent perhaps, in aged skin.

Adolescent↗
PubMed2003

Assessment of adapalene gel for the treatment of actinic keratoses and lentigines: a randomized trial.

BACKGROUND: Adapalene is a synthetic retinoid with an established clinical efficacy against acne and good local tolerability. Its effectiveness in the treatment of photodamaged skin has not been studied. OBJECTIVE: We sought to determine the safety and efficacy of adapalene gel in the treatment of actinic keratoses and solar lentigines. METHODS: In a prospective, 2-center, randomized, controlled, investigator-masked, parallel-group study, 90 patients with actinic keratoses and solar lentigines were treated daily with either adapalene gel (0.1% or 0.3%) or its vehicle gel for 4 weeks, followed by twice-daily applications, if tolerated, for up to 9 months. RESULTS: Of the 90 Caucasian patients (69 male, 21 female; mean age 63.1 years) who were enrolled into the study, 83 patients completed 9 months of treatment. With adapalene gel 0.1% and 0.3%, the mean number of actinic keratoses was reduced by 0.5 +/- 0.9 (mean +/- SE) and 2.5 +/- 0.9, respectively. Whereas, with the vehicle gel, there was an increase of 1.5 +/- 1.3 (P <.05). After 1 month of treatment, the patients who received adapalene had significant lightening of solar lentigines as compared with the patients who were treated with vehicle gel (P <.05). After 9 months, 57% and 59% of the patients had lighter lesions in the adapalene 0.1% and 0.3% groups, respectively, in comparison with only 36% in the vehicle group (P <.05). Histologic evaluations revealed improved cellular atypia and reduced epidermal melanin in adapalene-, as compared with vehicle-treated group. The differences, however, were not statistically significant. A retrospective evaluation of paired clinical photographs (before and after 9-month treatment) by 2 dermatologists who were treatment-blinded revealed significant improvement in wrinkles and other clinical features of photoaged skin with adapalene as compared with its vehicle. CONCLUSION: Adapalene gel 0.1% and 0.3% were well tolerated and improved actinic keratoses, solar lentigines, and other features of photodamaged skin.

Adapalene↗
PubMed2003

Matrix metalloproteinase-1 is the major collagenolytic enzyme responsible for collagen damage in UV-irradiated human skin.

Punch biopsies of human skin were obtained 1 day after irradiation with two minimal-erythema doses (MED) from either a UVB light source or a Solar Simulator and incubated in organ culture for 72 h. Organ culture fluids obtained at 24, 48 and 72 h were analyzed for collagenolytic activity and for reactivity with antibodies to matrix metalloproteinase-1 (MMP-1; interstitial collagenase) and MMP-13 (collagenase-3). High levels of collagenolytic activity were seen in organ culture fluid from skin exposed to either light source. MMP-1 was strongly induced in parallel, increasing from less than 100 ng/ml in organ culture fluid from control skin to approximately 1.1 microg/ml in culture fluid from UV-treated skin. Whereas most of the detectable MMP-1 in control culture fluid was represented by the latent form of the enzyme, approximately 50% of the enzyme was present as the active form in organ culture fluid of UV-exposed skin. In contrast, there was no detectable MMP-13 in control organ culture fluid and very little change after UV exposure (less than 100 ng/ml in both cases). Finally, neutralization studies with a blocking antibody to MMP-1 removed 95 +/- 4% of the collagenolytic activity in the organ culture fluid from UV-treated skin. These findings strongly implicate MMP-1 rather than MMP-13 as the major collagenolytic enzyme responsible for collagen damage in photoaging.

Adult↗