Search PubMed⌕ Search

Biomedical subjects

Kwang Hyun Cho

Publications and source records attributed to Kwang Hyun Cho.

31 records · Page 2Linked to original sources
PubMed2005

Poliosis circumscripta associated with neurofibroma.

A 32-year-old woman presented at our clinic with a moderately soft, nontender, subcutaneous mass in the left temporal region and white hairs overlying the swelling. The lesion was surgically excised, and there was no recurrence at one year postoperatively. On histological examination, the hair follicles overlying the subcutaneous mass were devoid of pigment and a poorly demarcated fibrocellular process was seen in the subcutaneous mass, which was typical of neurofibroma. To our knowledge, only one case of poliosis associated with neurofibroma has been previously reported.

Adult↗
PubMed2005

Topical photodynamic therapy using intense pulsed light for treatment of actinic keratosis: clinical and histopathologic evaluation.

BACKGROUND: Photodynamic therapy (PDT) is suitable for the treatment of actinic keratosis, and, recently, topical PDT using intense pulsed light as a light source has been reported. However, evaluations of its therapeutic effects have been clinically based. OBJECTIVE: The objective of this study was to confirm the histopathologic resolution of actinic keratosis treated by topical PDT using intense pulsed light as a light source. METHODS: Twelve actinic keratosis lesions in seven patients were treated with 5-aminolevulinic acid-PDT using intense pulsed light as a light source. After a single treatment, the clinical response was assessed and histopathologic examinations were performed on clinically resolved lesions. RESULTS: Six of 12 (50%) lesions showed clinical clearance after a single treatment, but histologic examinations showed that only 5 of the 12 (42%) lesions had been removed. No complications, such as pigmentary changes or scarring, were observed. CONCLUSION: Intense pulsed light is potentially an effective light source for PDT. However, the determination of complete remission in actinic keratosis requires caution, and long-term follow-up or histologic confirmation may be required.

Aged↗
PubMed2004

Effect of minoxidil on proliferation and apoptosis in dermal papilla cells of human hair follicle.

BACKGROUND: Minoxidil has been widely used to treat androgenetic alopecia, but little is known about its pharmacological activity or about the identity of its target cells in hair follicles. We hypothesized that minoxidil has direct effects on the proliferation and apoptosis of dermal papilla cells (DPCs) of human hair follicle. OBJECTIVE: To elucidate the mechanism of topical minoxidil action in terms of stimulating hair growth. METHODS: We evaluated cell proliferations in cultured DPCs by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) and measured the expressions of extracellular signal-regulated kinase (ERK), Akt, Bcl-2, and Bax by Western blot. We also measured elongation of hair follicles in organ culture. RESULTS: Minoxidil significantly increased the proliferation of DPCs. The levels of ERK phosphorylation and of phosphorylated Akt increased significantly 1 h post-treatment; percentage increase of ERK phosphorylation was 287% at 0.1 microM and 351% at 1.0 microM of minoxidil, and that of Akt phosphorylation was 168% at 0.1 microM and 257% at 1.0 microM of minoxidil. 1.0 microM of minoxidil increased Bcl-2 expression over 150%, while 1.0 microM of minoxidil decreased Bax expression by more than 50%. Moreover, a significant elongation of individual hair follicles in organ culture was observed after adding minoxidil. CONCLUSION: Minoxidil promotes the survival of human DPCs by activating both ERK and Akt and by preventing cell death by increasing the ratio of Bcl-2/Bax. We suggest that minoxidil stimulates the growth of human hairs by prolonging anagen through these proliferative and anti-apoptotic effects on DPCs.

Adult↗
PubMed2004

Selective COX-2 inhibitor, NS-398, inhibits the replicative senescence of cultured dermal fibroblasts.

Cyclooxygenase 2 (COX-2) is known to be increased in aged cells. Recent studies suggest that the increased expression of COX-2 may be involved in the pathogenesis of age-associated diseases such as rheumatoid arthritis and cancer. We investigated the role of COX-2 in cell cycle arrest and collagen deficiency during the aging process. Using the replicative senescence model of dermal fibroblasts, we demonstrated the increased expression of COX-2 and increased PGE(2) levels associated with replicative senescence. Replicative senescent cells showed a decreased ability to induce cell proliferation, probably due to the increased expression of the p53 protein and the decreased expression of the PCNA protein, and also showed increased expression of MMP-1, and decreased expression of tissue inhibitor of metalloproteinase-1 (TIMP-1) and procollagen. The selective COX-2 inhibitor, NS-398, can inhibit the senescence-associated increases of COX-2, PGE(2), p53 and MMP-1 expression, and the senescence-associated decreases of PCNA, TIMP-1 and procollagen expression. These results suggest that the increased level of COX-2 and higher level of PGE(2) in aged cells may play an important role in cellular senescence, and that selective COX-2 inhibitors may be useful for the intervention of skin aging.

Arthritis, Rheumatoid↗
PubMed2004

Acral lentiginous melanoma in situ: a study of nine cases.

An acral lentiginous melanoma (ALM) is the most common type of cutaneous melanoma in Asians. However, it is unusual to encounter a patient showing only the histologic features of an ALM in situ. Here we describe clinical and histologic features of nine cases of ALM in situ including immunohistochemical staining with anti-S100 protein and HMB-45. All the patients had a long clinical history. Clinically, the lesions were characterized by a longitudinal pigmented streak in the nail plates, black pigmentation on the proximal or lateral nail fold, and an irregular border and variegated pigmentation on the sole or thumb. Total resections of the lesions were performed in all patients. All lesions, in both biopsy and excisional specimens demonstrated more melanocytes generally located in the basal layer of the epidermis. There was no dermal invasion. No recurrence of the disease had occurred in any patient after a follow-up period of between 6 months to 12 years after surgery. These results suggest that ALM can evolve slowly over many years.

Adult↗
PubMed2004

Lupus panniculitis with combined features of dermatomyositis resulting in severe lipoatrophy.

An 11-year-old girl presented with a one-year history of multiple, hard, slightly painful subcutaneous nodules on her right cheek, upper arms, and buttock. Histology of a skin biopsy specimen showed a lobular panniculitis. Laboratory studies revealed positive ANA, anti-double strand DNA, and elevated muscle enzymes. She was diagnosed as having lupus panniculitis. During hydroxychloroquine treatment, erythema over knuckle joints developed. These unusual clinical and laboratory findings of panniculitis associated connective tissue diseases made it difficult to make a precise diagnosis. We report this unusual case of lupus panniculitis with combined features of dermatomyositis resulting in severe lipoatrophy.

Biopsy, Needle↗
PubMed2004

[Usefulness of urinary trypsinogen-2 dipstick test for diagnosis of acute pancreatitis].

BACKGROUND/AIMS: The clinical usefulness of urinary trypsinogen-2 dipstick test is still in controversy. We evaluated the usefulness of urinary trypsinogen-2 dipstick test in patients with acute pancreatitis. METHODS: Urinary trypsinogen-2 dipstick test was prospectively performed in 50 patients with acute pancreatitis, 50 patients with non-pancreatic abdominal pain, and 50 healthy controls. RESULTS: On admission, urinary trypsinogen-2 dipstick test was positive in 36 of 50 patients with acute pancreatitis (sensitivity, 72%) and in 4 of 50 patients with non-pancreatic abdominal pain (specificity, 92%). On the other hand, it was all negative in controls. The sensitivity and specificity of serum lipase were 78% and 94%, respectively. At 24 hours after admission, the positive rate of urinary trypsinogen-2 dipstick test rose from 72% to 94% (p=0.02). The results of urinary trypsinogen-2 dipstick test was positive in 14 of 15 patients with severe pancreatitis and 22 of 35 patients with mild pancreatitis according to the criteria by Atlanta International Symposium, 1992. CONCLUSIONS: Urinary trypsinogen-2 dipstick test is comparable to serum lipase in diagnosing acute pancreatitis. Delayed measurement and severe pancreatitis are more likely to yield positive results with urinary trypsinogen-2 dipstick test. Thus, we suggest that the cut-off value of urinary trypsinogen-2 dipstick test should be lowered to increase its sensitivity.

Acute Disease↗
PubMed2003

Dual mechanisms of green tea extract (EGCG)-induced cell survival in human epidermal keratinocytes.

Beneficial effects attributed to green tea, such as its anticancer and antioxidant properties, may be mediated by (-)-epigallocatechin-3-gallate (EGCG). In this study, the effects of EGCG on cell proliferation and UV-induced apoptosis were investigated in normal epidermal keratinocytes. When topically applied to aged human skin, EGCG stimulated the proliferation of epidermal keratinocytes, which increased the epidermal thickness. In addition, this topical application also inhibited the UV-induced apoptosis of epidermal keratinocytes. EGCG was found to increase the phosphorylation of Bad protein at the Ser112 and Ser136. Moreover, EGCG-induced Erk phosphorylation was found to be critical for the phosphorylation of Ser112 in Bad protein, and the EGCG-induced activation of the Akt pathway was found to be involved in the phosphorylation of Ser136. Furthermore, EGCG increased Bcl-2 expression but decreased Bax expression, causing an increase in the Bcl-2-to-Bax ratio. In addition, we demonstrate the differential growth inhibitory effects of EGCG on cancer cells. In conclusion, this study demonstrates that EGCG promotes keratinocyte survival and inhibits the UV-induced apoptosis via two mechanisms: by phosphorylating Ser112 and Ser136 of Bad protein through Erk and Akt pathways, respectively, and by increasing the Bcl-2-to-Bax ratio. Moreover, these two proposed mechanisms of EGCG-induced cell proliferation may differ kinetically to promote keratinocyte survival.

Apoptosis↗
PubMed2002

Differential effects of photoaging vs intrinsic aging on the vascularization of human skin.

OBJECTIVE: To quantify the distinct effects of photoaging vs intrinsic aging of human skin on cutaneous vascularization in the Korean population. DESIGN: Case series. SETTING: University hospital. PARTICIPANTS: A total of 21 healthy Korean volunteers from the third to the ninth decades of life. INTERVENTION: Skin biopsy specimens were obtained from chronically sun-exposed and sun-protected skin of each participant. MAIN OUTCOME MEASURES: Frozen sections were stained for the platelet endothelial cell adhesion molecule CD31 (PECAM-1), and computer-assisted quantitative image analysis was performed to quantify cutaneous vascular density and vessel size. RESULTS: Intrinsically aged and photoaged skin showed an age-dependent reduction of cutaneous vessel size. However, only photoaged skin exhibited significantly reduced numbers of dermal vessels, in particular in the subepidermal areas that displayed extensive matrix damage. Linear regression analysis revealed an inverse relation of vessel numbers and age in sun-damaged, but not in sun-protected, skin. CONCLUSIONS: In Korean skin, chronic photodamage results in a gradual decrease in the number and size of dermal vessels over several decades of sun exposure, most likely due to degenerative changes of the dermal extracellular matrix. Because the present investigation was restricted to ethnic Korean volunteers, future studies are needed to evaluate whether similar changes can be observed in whites.

Adult↗