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Biomedical subjects

J I Youn

Publications and source records attributed to J I Youn.

At least 19 recordsLinked to original sources
PubMed1999

A long-term time course of colorimetric evaluation of ultraviolet light-induced skin reactions.

Many attempts have been made to quantify ultraviolet (UV) radiation-induced erythema and pigmentation. However, most of these studies were concerned with the early changes of reactions and neglected events occurring in later stages. The long-term course of skin colour changes in pigmented skin, induced by broad band UVA and UVB radiation, was evaluated in 30 Korean male volunteers by means of a tri-stimulus colorimeter for 10 weeks. The L*a*b* system recommended by the Commission International de l'Eclairage was used to measure skin colour. The L* value (luminance) gives the relative lightness ranging from total black to total white. The a* value represents the balance between red and green and the b* value the balance between yellow and blue. The mean individual typology angle of our subjects was 47.3 degrees, indicating 'light' group of constitutional skin colour category. One day after UV exposure, the L* and b* values decreased significantly, following the colour direction of persistent pigment darkening. They then changed in opposite directions persistently until week 1, when maximum tanning was obtained. Then, a shift toward the original values was observed parallel to the constitutive melanization axis. The a* index showed a significant increase toward the mean colour of haemoglobin on day 1. It returned to its original value following the pathway of constitutive melanization axis. This promising quantitative method may enable objective measurement of dermatophysiologic changes to be made, and allow evaluation of the efficacy of therapeutic modalities on skin disorders without the inherent errors associated with subjective judgement. Our results would provide standard data for long-term UV-induced skin erythema and pigmentation.

Adult↗
PubMed1999

Vitamin D receptor polymorphism is associated with psoriasis.

Vitamin D receptor is a trans-acting transcriptional factor that mediates 1alpha,25-dihydroxyvitamin D3 action in the regulation of target gene expression. Recent studies have shown that clinical response of psoriasis to 1alpha,25-dihydroxyvitamin D3 is correlated with the vitamin D receptor mRNA expression level, which may be influenced by the genotype of the vitamin D receptor. In this study, we have explored a possible association between psoriasis and the polymorphism in the gene encoding the vitamin D receptor. We examined the allelic frequencies of the vitamin D receptor in psoriasis patients (n = 104) and in healthy controls (n = 104) by analyzing the restriction pattern of the polymerase chain reaction products. A significant increase in the frequency of the A allele (absence of the restriction site at intron 8) by ApaI restriction fragment length polymorphism was observed in psoriasis patients compared with that of the control group, and the tendency was more accentuated in early onset psoriasis. Odds ratios (95% confidence interval) for psoriasis of AA and Aa genotypes were 5.0 (1.3-19.1) and 2.4 (1.3-4.3), and odds ratios for early onset of AA and Aa genotypes were 6.4 (1.6-25.0) and 3.1 (1.7-5.9), respectively. Allele frequencies for A and a alleles were 0.317 and 0.683 in the psoriasis group and 0.168 and 0.832 in the control group (p = 0.001). A significant association between vitamin D receptor genotypes and the mean age at onset was observed (p < 0.05). Our findings suggest that allelic variance in the vitamin D receptor gene itself or other genes in linkage disequilibrium with this gene, could predispose to the development of psoriasis.

Adolescent↗
PubMed1999

The effect of glycolic acid on photoaged albino hairless mouse skin.

BACKGROUND: Several clinical reports have suggested that alpha hydroxy acids (AHAs), including glycolic acid, may improve photoaging. However, the mechanism of action of glycolic acid is not well understood. OBJECTIVE: In order to investigate the mechanism of action of glycolic acid in improving photoaged skin, we observed the effect of glycolic acid on collagen metabolism and wrinkle effacement in chronically ultraviolet B (UVB) irradiated mice. METHODS: Skh:HR-1 mice were exposed to UVB for 10 weeks and then treated topically with 15% glycolic acid for 10 weeks. We assessed the improvement in wrinkling, the depth of the dermal repair zone, and the extent of the increase in collagen synthesis. RESULTS: At treatment week 10, the glycolic acid-treated mice showed a significant decrease in wrinkle score, an increased thickness of the dermal repair zone, and an increase in the amount of collagen synthesized compared to vehicle (hydrophilic ointment base) treated mice. CONCLUSION: Topically applied glycolic acid may improve photoaging through modulation of collagen production.

Animals↗
PubMed1998

The photoprotective effect of 1,25-dihydroxyvitamin D3 on ultraviolet light B-induced damage in keratinocyte and its mechanism of action.

We investigated the photoprotective effect of 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) both in vivo and in vitro, revealing its relationship with glutathione, a well-known antioxidant. We also probed into the possible mechanism of photoprotection of 1,25(OH)2D3 through immunohistochemical study for metallothionein (MT). At the same time, endogenous antioxidant effect of 1,25(OH)2D3 was examined. Survival of cultured human keratinocytes was decreased when the cells were irradiated with ultraviolet light-B (UVB) at doses above 30 mJ/cm2. But in the presence of 1,25(OH)2D3 (12 nM), the decrease of survival of keratinocytes by UVB was diminished. The formation of sunburn cells by UVB irradiation in the skin of ICR mice was inhibited by topical application of 1,25(OH)2D3, regardless of prior glutathione depletion. Immunohistochemical staining revealed that 1,25(OH)2D3 induced the expression of MT, a potent radical scavenger, mainly in the basal layer of ICR mice skin. 1,25(OH)2D3 neither inhibited peroxidation of plasma lipids nor interacted with superoxide, nor removed hydrogen peroxide as an antioxidant. These findings suggest that 1,25(OH)2D3 has photoprotective effect not related with glutathione or its endogenous antioxidant property. Rather, it could be attributed to 1,25(OH)2D3-induced MT and its capacity to prevent radical-related damage in UVB irradiation.

Animals↗
PubMed1998

Apoptosis in the pathogenesis of cutaneous lupus erythematosus.

Defective regulation of apoptosis may play a role in the development of autoimmune diseases such as systemic lupus erythematosus, in which the skin is a prominent target. To our knowledge, however, the nature of epidermal changes in cutaneous lupus erythematosus (LE) has not previously been investigated. We investigated the involvement of apoptosis in cutaneous LE. A total of 44 lesional skin samples from patients with cutaneous LE, 44 skin samples from patients with scleroderma, five skin specimens from patients suffering from dermatomyositis, and 13 normal skin samples were stained immunohistochemically with monoclonal antibodies to Ki-67, p53 (DO-7), and bcl-2. The lesional skin from cutaneous LE, except LE profundus, showed a marked increase in Ki-67- and p53-positive keratinocytes, which were predominantly located in the basal layer of the epidermis and follicle, and a drastic reduction in the number of bcl-2-positive cells localized in the basal cell compartment. With TdT-mediated dUTP-biotin nick end-labeling staining, we demonstrated that extensive apoptosis occurred in almost the whole epidermis of cutaneous LE, except in cases of LE profundus. This abnormal expression of Ki-67, p53, and bcl-2 and the occurrence of apoptosis in the epidermis was also observed in epidermis from patients with dermatomyositis, but not in that from patients with scleroderma.

Apoptosis↗
PubMed1998

Factors influencing psoriasis: an analysis based upon the extent of involvement and clinical type.

A variety of external stimuli are accepted as important in modifying the severity of psoriasis. We sought to determine whether there is any difference in the influence of external factors on psoriasis in relation to extent of involvement or clinical type. A total of 870 psoriasis patients seen between 1982 and 1995 were categorized as mild, moderate, or severe on the basis of extent of the disease, and as guttate, nummular/plaque, or exfoliative/generalized pustular according to clinical type. We then performed a questionnaire survey concerning the influence of external factors such as seasonal changes, sunlight, stress, and pregnancy. These data sets were combined and analysed. The majority of patients stated favorable effects of summer, sunlight, and pregnancy and adverse effects of winter and stress. A statistically significant correlation was noted between the extent of psoriasis and the proportion of patients stating that their disease worsened at times of psychological stress (p < 0.01). We confirmed that psoriasis patients with more extensive involvement experience greater fluctuations in their condition, notice these changes, and therefore relate them to psychological stress.

Adolescent↗
PubMed1998

The effectiveness of modified ingram therapy compared with severity of psoriasis.

To treat cases of psoriasis, various modifications of the original Ingram method were tested for increased effectiveness and minimized side reactions. Our modified method consists of 0.1-0.5% anthralin ointment application and selective UVB phototherapy with adjunctive warm water bath and the application of emollients. The object of this study was to evaluate the effectiveness and duration of remission in response to our modified Ingram method and compare the data with the severity of psoriasis. The clearing rate was higher and the failure rate was lower in the moderate group. The number of occasions on which therapy was used and the duration of this therapy were greater in the severe group, but there were no significant differences except for the number of occasions of therapy to the trunk. Fifty-eight percent of the moderate group did not relapse in more than one year, but 63% of the severe group relapsed within six months. The results of this study showed that the modified Ingram regimen is an effective therapeutic modality in psoriasis, especially in the moderate group.

Administration, Topical↗
PubMed1997

Regulations of collagen synthesis by ascorbic acid, transforming growth factor-beta and interferon-gamma in human dermal fibroblasts cultured in three-dimensional collagen gel are photoaging- and aging-independent.

Decreased collagen synthesis and loss of responsiveness to growth factors are well known phenomena in in vivo or in vitro aged cells. Ascorbic acid and some cytokines such as transforming growth factor-beta and interferon-gamma are important regulators of collagen synthesis. To investigate the responsiveness of fibroblasts with regard to the photoaging and aging process, we examined the effect of ascorbic acid, TGF-beta, and IFN-gamma on collagen synthesis in dermal fibroblasts from three newborn foreskins (1 day old) and in both exposed and unexposed skin fibroblasts from 4 old individuals (60-76 years old) cultured in monolayer and in collagen gel. We demonstrated that basal levels of collagen synthesis decreased with increasing age. Photoaged fibroblasts in collagen gel showed greater basal collagen synthesis than aged fibroblasts in the same individuals, but similar basal collagen synthesis in monolayer cultures. Even though basal levels of collagen synthesis in collagen gel are downregulated in a photoaging- and aging-dependent manner, collagen synthesis by ascorbic acid in collagen gel, and by TGF-beta and IFN-gamma in both monolayer culture and collagen gel were regulated in a photoaging- and aging-independent manner. In monolayer culture, however, the responsiveness to ascorbic acid in newborn fibroblasts was greater than in photoaged and aged fibroblasts. Our results suggest that there are differences in collagen synthesis between photoaged and aged cells, depending on culture conditions. Responsiveness to ascorbic acid, TGF-beta and IFN-gamma related to collagen synthesis in photoaged and aged fibroblasts in collagen gel appears to be the same as in newborn fibroblasts, even though basal levels of collagen synthesis are downregulated in a photoaging- or aging-dependent manner.

Aged↗
PubMed1997

Photoprotective effect of calcipotriol upon skin photoreaction to UVA and UVB.

It has been shown that 1,25-dihydroxyvitamin D3 has a photoprotective effect against UVB injury in mouse skin and cultured rat keratinocytes by induction of metallothionein (MT). Calcipotriol is a synthetic analogue of 1,25-dihydroxyvitamin D3 with equipotent cell regulating properties, but with a lower risk of calcium-related side effects. The aim of the present study was to see whether calcipotriol has a photoprotective property both in vitro and in vivo. We examined the effect of calcipotriol on UV-induced damage of cultured human keratinocytes through a cell viability assay, and measurement of DNA synthesis by cultured keratinocytes, on UV-induced damage of mouse skin and on minimal erythema dose (MED). We found that calcipotriol was protective against UVB-induced reduction in DNA synthetic activity of cultured keratinocytes in relatively low doses (20 and 40 mJ/cm2) of UVB. With phototesting following application of calcipotriol, five subjects among 10 healthy volunteers and three among six psoriasis patients showed an increase in MED compared with the vehicle-treated site. These findings imply that calcipotriol may be photoprotective and that more extensive studies with various doses of UV irradiation and modes of calcipotriol delivery are required.

Administration, Cutaneous↗
PubMed1997

GM-CSF production by epithelial cell line: upregulation by ultraviolet A.

It was demonstrated that UVB increases synthesis and expression of IL-1 alpha and GM-CSF by keratinocytes. Upregulation of GM-CSF by UVB is reported to be mediated by IL-1 alpha. However, regulation of IL-1 alpha and GM-CSF by UVA is not well-known. The purpose of the present study was to evaluate the effects of UVA on IL-1 alpha and GM-CSF production. Here we used a competitive RT-PCR for measuring cytokine gene expression in an epidermal cell line after UVA irradiation. IL-1 alpha and GM-CSF mRNA did not show any change at 1 h and 6 h following exposure to UVA. After UVA irradiation, however, IL-1 alpha mRNA decreased and GM-CSF mRNA increased at 24 h and the level of GM-CSF in culture supernatant increased at 24 h and 48 h. Addition of antihuman IL-1 alpha neutralizing antibody to UVA irradiated cells did not prevent the increase of GM-CSF mRNA expression. These results suggest that UVA radiation may induce GM-CSF production through an IL-1 alpha independent pathway.

Antibodies↗
PubMed1997

Neutrophilic dermatoses associated with myeloid malignancy.

The neutrophilic dermatoses are significantly associated with myeloid malignancies. We now describe the clinical and histological features of 11 patients with these disorders, namely Sweet's syndrome in three cases, pyoderma gangrenosum in two, and neutrophilic eccrine hidradenitis in one; there were also five others which could not be categorised as recognised entities. Our observations, as well as those from a review of the literature, support the hypothesis that in the neutrophilic dermatoses associated with myeloid malignancy, a common mechanism may be involved.

Adult↗
PubMed1996

Histological responses of port wine stains in brown skin after 578 nm copper vapor laser treatment.

BACKGROUND AND OBJECTIVES: The object of this study is to characterize the effects of epidermal melanin in brown skin on selective vessel damage by copper vapor laser radiation in port wine stain (PWS). STUDY DESIGN/MATERIALS, AND METHODS: We observed the histological changes of PWS in Korean patients who received copper vapor laser (578 nm) treatment over a range of energy densities (6-14 J/cm2) and exposure durations (30-200 ms). The nitroblue tetrazolium chloride (NBTC) staining method was used to differentiate between the blue-stained viable cells and the unstained thermally damaged cells. RESULTS: With Fontana-Masson stain, we found that Korean skin has more epidermal melanin than Caucasian skin. For energy densities greater than 6 J/cm2, epidermal damage was observed. At 6 and 8 J/cm2, the damage to the dermis was localized to the blood vessels and the perivascular tissue. The connective tissue between damaged vessels and epidermis was still viable. Energy densities above 10 J/cm2 produced a diffuse thermal necrosis. We conclude that vascular selectivity without epidermal damages cannot be achieved with a 50 ms exposure at 578 nm in the brown skin of Koreans. The energy density for clinical minimal whitening was 6-8 J/cm2, and the maximum penetration depth of these energy densities was 0.4 mm. We also found that the epidermal damage increased with increasing pulse widths at a fixed energy density (10 or 8 J/cm2) while the severity and depth of vascular damage decreased. These findings suggest that it is best to treat PWS with a copper vapor laser at the minimal pulse width and maximal power output possible at given energy density. CONCLUSION: We have demonstrated that the copper vapor laser treatment of PWS in the brown skin is not as selective as in white skin because of epidermal melanin.

Adult↗
PubMed1996

Change of glutathione S-transferases in the skin by ultraviolet B irradiation.

Glutathione S-transferases (GSTs) may play an important role in protecting skin from ultraviolet radiation (UVR). However, the study on the response of GST to UVR is limited at present. We have examined the effects of a single exposure to ultraviolet B (UVB) radiation on GST in cultured human keratinocytes and the epidermis of SKH/hr-1 hairless mice. We have also investigated the changes of skin GST by chronic irradiation of UVB on the hairless mice. Significant decreases in GST activities in vitro and in vivo were observed at 24 h after 30 and 50 mJ/cm2 UVB irradiation. Chronic UVB exposure also caused decrease in GST activities of the skin tissue. However, any changes in mRNA expression or protein amount of GST have not been observed by Northern blot analysis and Western blot analysis after 30 mJ/cm2 UVB irradiation in cultured human keratinocytes, which suggests that mRNA expression and protein amount of GST are not affected by UVB. These results suggest that UVB irradiation results in inhibitory effect on GST activity in the skin.

Animals↗