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Biomedical subjects

H C Eun

Publications and source records attributed to H C Eun.

At least 55 records · Page 3Linked to original sources
PubMed1996

Loss of contact sensitization evaluated by laser Doppler blood flowmetry and transepidermal water loss measurement.

Allergic contact dermatitis, which is mediated by activated T cells through a Type IV reaction, is usually believed to persist throughout life. There have been several reports of spontaneous loss of sensitization, e.g., loss of previous patch test reaction or loss of allergic contact dermatitis withal continuous exposure to the allergens. However, these have been well quantified. The aim of this study was to confirm the development of desensitization or hyposensitization with the aid of objective measurements. A total of 18 patients with alopecia areata, who received 4 months diphenylcyclopropenone (DPCP) contact immunotherapy, were patch tested and the responses were measured by laser Doppler blood flowmetry (LDF) and transepidermal water loss (TEWL). Patch tests were performed 2X, before and after 4 months of immunotherapy. To determine whether local desensitization developed, we compared change of DPCP concentrations producing mild contact dermatitis on the scalp. Our results showed that systemic and local hyposensitization occurred in human subjects by weekly applications of low concentrations of DPCP for 4 months. LDF seems to be more correlated with visual scores than TEWL measurement.

Administration, Topical↗
PubMed1996

Enhanced proliferation and collagen synthesis of human dermal fibroblasts in chronically photodamaged skin.

Cutaneous aging can be divided into intrinsic aging and photoaging. We investigated the influence of aging and photoaging on the proliferation and collagen synthesis of human dermal fibroblasts cultured 3-dimensionally in a collagen gel. We examined 11 human dermal fibroblast cell lines cultured from 3 newborn skins (1 day old), and both exposed and unexposed skin from 4 elderly volunteers (60, 60, 73, 76 years old), respectively. Newborn fibroblasts actively proliferated within the attached collagen gels compared with the elderly cell lines. Within the attached collagen gels in the presence of 10% fetal calf serum (FCS), the fibroblasts from exposed skin proliferated rapidly compared with fibroblasts from unexposed skin from the same individuals. In collagen gel and monolayer cultures with 1% FCS, the percentage of collagen synthesized by photoaged and aged fibroblasts decreased significantly compared with that by newborn fibroblasts. When the fibroblasts were cultured three dimensionally in attached collagen gels in the presence of 1% FCS, the relative levels of collagen synthesis by cultured fibroblasts from photoaged skin were increased significantly compared with those of aged skin fibroblasts from the same individuals. These results suggest that fibroblasts of exposed skin may be more active than those of unexposed skin and that the three-dimensional culture of fibroblast can be used as a model to investigate the influence of aging and photoaging on cell functions.

Aged↗
PubMed1995

A study of skin responses to follow-up, rechallenge and combined effects of irritants using non-invasive measurements.

Irritant contact dermatitis is a common clinical problem. Primary irritation can be easily recognized, but cumulative irritation by daily exposure is hard to be diagnosed and the condition may fail to be clear even away from work. The mechanism of irritant dermatitis produced by repeated or combined exposure to clinical or subclinical doses of irritants is still poorly understood. In order to find out whether the subclinical doses of irritants affect each other by repeated or combined exposure according to their concentrations, non-invasive measurements, transepidermal water loss and laser Doppler flowmetry were used. Sodium lauryl sulfate, sodium hydroxide and benzalkonium chloride were serially diluted and patch-tested with large Finn chambers on Scanpor tape on the back of normal human volunteers and responses were followed up for 7 days. Twice repeated exposure with subclinical doses of irritants at 1 day intervals were also performed. Repeated daily applications for 5 days with subclinical doses of single or premixed irritants were performed to know the combined irritating effect. The irritant response was well correlated to the concentration of the irritants. However, increased response was not observed when subclinical doses were rechallenged on the previously patch tested sites. Twice-repeated exposure of subclinical doses of irritants increased skin irritancy when measured by transepidermal water loss and laser Doppler flowmetry. Some correlation and some discrepancies were observed between different evaluation methods in combined and repeated application tests with irritants of subclinical doses. Responses of skin irritancy induced by subclinical doses showed somewhat different pattern from that given strong irritants.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1995

Erythema induratum with pulmonary tuberculosis: report of three cases.

Three cases of erythema induratum which occurred in the patients with pulmonary tuberculosis are described. The cutaneous lesions were violaceous, indurated nodules on both lower legs above the malleoli. Histologically, tuberculoid granuloma with caseation necrosis was found in one case; necrotizing vasculitis was the prominent finding in other two cases. The erythema induratum promptly responded to antituberculous therapy. We believe that, in light of these cases, the association between erythema induratum and infection with tubercle bacilli should be re-emphasized.

Adult↗
PubMed1994

A comparative study of the cytotoxicity of skin irritants on cultured human oral and skin keratinocytes.

The cytotoxicity of irritants on human oral and skin keratinocyte culture models was compared. Keratinocytes were exposed to sodium lauryl sulphate and benzalkonium chloride at concentrations of 10(-4)-10(-7) M for 24 h. Cytotoxicity was evaluated by changes in mitochondrial metabolic activity (MTT assay) and plasma membrane integrity (LDH leakage). Our results showed that oral and skin keratinocytes are equally sensitive to the irritants tested. There were marked similarities in susceptibility between each cell type cultured from six individuals. The immunohistochemical staining pattern of both cell types resembled that of the basal cell. These observations suggest that the skin keratinocyte culture model may be useful in evaluating the cytotoxicity of agents which are irritants on either the skin or oral mucosa.

Adolescent↗
PubMed1994

Comparison of irritant potential of shampoos using cultured human epidermal keratinocytes model and patch test reaction measured by laser Doppler flowmetry.

The keratinocyte culture model has previously been used as an in vitro method for testing skin irritating potential of common skin irritants. However, solubility limits its use for finished products. Shampoo is very soluble in water which should make it an ideal product category for the cell culture model. To determine the skin irritant potential of several commercial shampoos, we employed cultured human keratinocytes as an in vitro model. 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide test (MTT) and lactic dehydrogenase release (LDH) test were used to document cell toxicity. 7 volunteers were patch tested and their reactions evaluated using laser Doppler flowmetry and compared with the in vitro data. MTT and LDH have a good negative correlation with each other. Patch test reaction, especially at high concentrations, correlates relatively well with the in vitro test, especially with shampoos of strong and weak irritancy. However, the rank order of the shampoos of moderate toxicity was not the same as in the in vitro data. This suggests that the cell culture technique cannot directly replace in vivo methods, and that data obtained by the cell culture method should be interpreted carefully.

Adult↗
PubMed1991

Patch test responses to rockwool of different diameters evaluated by cutaneous blood flow measurement.

Rockwool is a man-made mineral fiber used mainly for insulation, which can cause mechanical skin irritation. This study was performed to evaluate the irritant potential of rockwools of different diameters and to compare the change of blood flow, measured by laser Doppler flowmetry, at different patch test occlusion times with rockwools. Rockwool A (mean diameter 4.20 +/- 1.96 mu) was more irritating than rockwool B (mean diameter 3.20 +/- 1.5 mu). The difference was more clearly observed in a 48-h patch test than in an 8-h or 24-h test. We concluded that laser Doppler blood flow measurement was a useful experimental tool for the evaluation of irritant patch test responses to mechanical irritants like rockwool, and that 48 h or more of occlusion time was necessary to produce irritant patch test responses to certain types of rockwool.

Construction Materials↗
PubMed1990

Dose-response relationships for topically applied antigens.

Patch-test responses to serially diluted nickel sulphate and potassium dichromate solutions in patients with nickel and chrome sensitivity were assessed by pulsed A-scan ultrasound to determine skin thickness and laser-Doppler flowmeter techniques to evaluate blood flow, as well as clinical scoring. There was a relationship between the dose of antigen and the test responses as measured by ultrasound and laser-Doppler flowmeter techniques in both nickel and chrome sensitive patients. Our data suggest that both techniques may be useful in the detection of allergic contact dermatitis in which there is a doubtful patch-test reaction as well as in experimental sensitization studies.

Chromium↗
PubMed1985

Contact dermatitis due to madecassol.

Madecassol is an extract of Centella asiatica, a member of the Umbelliferae family. It contains madecassic acid, asiatic acid and asiaticoside. It has been used as a wound healing agent and for the prevention of cicatrization. We report contact dermatitis due to Madecassol and a control study with its individual ingredients.

Adolescent↗
PubMed1984

Occupational burns.

Certain occupations cause particular kinds of burn. Minor burns are usually neglected. Observation of industrial workers during routine annual medical examination found many workers with minor occupational burns and their sequalae. Some were so characteristic that they can be regarded as occupational marks.

Burns↗