Nonablative rejuvenation with lasers

여운철 ( Un Cheol Yeo ) 대한피부과학회 2015 대한피부과학회 학술발표대회집 Vol.67 No.2

림프부종 환자에서 Dermascan - C 와 조직생검을 이용한 피부 두께의 비교

여운철 ( Un Cheol Yeo ) 대한피부과학회 1997 대한피부과학회지 Vol.35 No.4

Background: Dermascan-C(Cortex technology, Denmark) is the 20MHz high-frequency ultrasonographic instrument which is suitable for skin measurement due to its high resolution compared to conventional 10MHz ultrasonographic machine. High frequency ultrasonography has been used for evaluating skin thickness by several investigators. There has been little data regarding to the evaluation of lymphedema using high-frequency ultrasonography. Objective : In this study, we examined skin thickness of lymphedema using Dermascan-C and compared the results with those of skin biopsy. Methods : Eight patients with various clinical stage of lymphedema were investigated. Skin biopsy and ultrasonographic measurement was done at the same lymphedema sites. In skin biopsy skin thickness was measured from horny layer to dermosubcutaneous junction. In ultrasonographic evaluation, the same site was measured using automatic algorithm provided by in-built image analyzer in Dermascan-C. Results : In five cases, the skin thickness measured by both methods are consistent, but in three cases it was impossible to measure skin thickness using Dermascan-C. Conclusion : Ultrasonographic evaluation using Dermascan-C could be useful to measure skin thickness in lymphedema. But, measuring skin thickness using Dermascan-C is difficult when the skin is very edematous or has subcutaneous fibrosis. (Kor J Derrnatol 1997;35(4): 752-757)

의학적 피부관리를 위한 의료기기의 사용과 법률에 대한 고찰

여운철 ( Un Cheol Yeo ),정찬우 ( Chan Woo Jeong ),한승경 ( Seung Kyung Hann ),김홍직 ( Hong Jig Kim ),한을남 ( Eul Nam Han ),박기범 ( Ki Beom Park ),최광호 ( Kwang Ho Choi ),목혜수 ( Hae Soo Mok ),문병천 ( Byung Chun Moon ),김용상 대한피부과학회 2009 대한피부과학회지 Vol.47 No.11

Background: Medical skin care is essential for the treatment of skin diseases all over the world. Medical skin care is also part of medical practice and this must be differentiated from the simple skin care that is given for normal healthy skin. Objective: We wanted to discuss medical skin care and the related medical devices and legal issues. Methods: We reviewed the related laws and regulations, we consulted experts and associations and we analyzed the result of the survey. Results: Legally, medical skin care and simple skin care are well classified. However, many illegal procedures are still performed by non-medical personnel and many adverse effects have been reported as a result. Furthermore, there are no legal restrictions for the performer based on the grade of each medical skin care procedure. Conclusion: For the best results and safe procedures, medical skin care must be performed by approved medical equipment under the supervision of a physician or medical personnel. Continuous control and guidance by the government is strongly needed. (Korean J Dermatol 2009;47(11):1236~1245)

악성 림프종 환자에서 발생한 다형홍반

여운철,조광현,이유신,허대석,이승철 ( Un Cheol Yeo,Kwang Hyun Cho,Yoo Shin Lee,Dae Seog Heo,Seung Chul Lee ) 대한피부과학회 1990 대한피부과학회지 Vol.28 No.5

A Case of Erythema Multiforme A ssociated with Malignant Lymphoma Un Cheol Yeo, M.D., Kwang Hyun Cho, M.D., Yoo Shin Lee, M.D., Dae Seog Heo*, M.D., Seoung Chul Lee**, M.D Department of Dermatology and Internal Medicine*, College of Medicine, Seoul National University, Seoul, Korea, Department of Dermatology**, College of Medicine, Inha University, Kyung Gi Do, Korea We report a case of erythema multiforme associated with malignant lymphoma. Fifty-six-year-old male patient visited our clinic complaining generalized skin lesions which were compatible with erythema multiforme clinically and histopathologically. The skin lesions were treatment-resistant, recurrent and persistent for 3 years. In consideration of old age, atypical features of erythema multiforme and no other demonstrable etiology of erythema multiforme, we studied for internal malignancy. Malignant lymphoma at the duodenum was revealed by UGI series, abdominal CT, and endoscopic biopsy. After chemotherapy, the tumor mass and active skin lesions were cleared simultaneously. Erythema multiforme may be regarded as one of the paraneoplastic syndromes.

Laser basics and physics

여운철 ( Un Cheol Yeo ) 대한피부과학회 2013 대한피부과학회 학술발표대회집 Vol.65 No.2

Laser treatment is so popular in cosmetic dermatologic treatment. But, the basic physics regarding laser treatment is so confusing. Whenever we encounter problem in laser treatment, we need to modify laser parameters according to individual cases. That is the moment we need vast variety of knowledge about laser basics and physics. Not only doctors but also paramecial persons should aware the mechanism of laser treatment to support doctor`s procedure. For this specific lecture, to enhance our understanding of laser, followings will be discussed 1. What is LASER ? light amplification by stimulated emission of radiation 2. Dosimetry energy(joule), power(watt), fluence(joule/cm2) fluence=dose=energy density fluence rate(W/cm2)= power density = irradiance = intensity 3. Laser tissue interaction reflection, scattering, transmission, absorption, 4. Chromophores in skin Water, oxy-hemoglobin, deoxy-hemoglobin, met-hemoglobin, melanin, fat 5. SPTL (selective photothermolysis) wavelength, pulse duration, fluence 6. Cooling cryogen spray cooling, contact cooling, air cooling.

MLSO 2 : Laser basics & physics

여운철 ( Un Cheol Yeo ) 대한피부과학회 2014 대한피부과학회 학술발표대회집 Vol.66 No.2

Laser treatment is so popular in cosmetic dermatologic treatment. But, the basic physics regarding laser treatment is so confusing. Whenever we encounter problem in laser treatment, we need to modify laser parameters according to individual cases. That is the moment we need vast variety of knowledge about laser basics and physics. Not only doctors but also paramecial persons should aware the mechanism of laser treatment to support doctor``s procedure. For this specific lecture, to enhance our understanding of laser, followings will be discussed 1. What is LASER ? light amplification by stimulated emission of radiation 2. Dosimetry energy(joule), power(watt), fluence(joule/cm2) fluence=dose=energy density fluence rate(W/cm2)= power density = irradiance = intensity 3. Laser tissue interaction reflection, scattering, transmission, absorption, 4. Chromophores in skin Water, oxy-hemoglobin, deoxy-hemoglobin, met-hemoglobin, melanin, fat 5. SPTL (selective photothermolysis) wavelength, pulse duration, fluence 6. Cooling cryogen spray cooling, contact cooling, air cooling

자외선에 의한 피부 염증 반응 : C57BL mouse의 귀부종 반응

여운철(Un Cheol Yeo),김기호(Ki Ho Kim),조미경(Mi Kyung Jo),전환표(Hwan Pyo Jeon),이주흥(Joo Heung Ree),이애영(Ai Young Lee),윤재일(Jai Il Youn) 대한피부과학회 1989 대한피부과학회지 Vol.27 No.6

This study was undertaken to investigate the change of ear swelling response (ESR) of the mice according to repetitive ultraviolet radiation. 100mJ/crn of UVB was irradiated daily for 4 weeks, and a total of 25 C57BL mice were used as subjects. The results were as follows : 1. After 1 day, 2 days and 3 days irradiation of UVB, ESR reached 21.3+1.5, 22.3+1.1 and 24.3+1.6 respectively with increasing tendency, but there was no statistical significance (Wilcoxon rank sum test p: 0.05). 2. ESR reached at maximum, 78.0+1.8, after 1 week(p<0.01), thereafter ESR decreased gradually with reparative process. 3. Inspite of continued irradiation, ESR decreased gradually after 2 weeks. After 2 weeks, 3 weeks and 4 weeks irradiation, ESR decreased to 51.6+11.8, 45.1+ 3.3 and 42.8-+6.8 respectively, but, there were still increment of ESR (p(0.01).

Principles of laser treatment of pigmentary lesions

여운철 ( Un Cheol Yeo ) 대한피부과학회 2016 대한피부과학회 학술발표대회집 Vol.68 No.2

Principle that underlie the treatment of pigmentary lesions is basically SPTL(selective photothermolysis). SPTL describes the destruction of melanosomes and death of melanocytes after laser treatment which has pulse duration around 10 nanoseconds. There exists other treatment options which are different from SPTL in particular aspects. Followings are the other options and explanation how they are different from SPTL. 1. pulse duration is longer than nsecond Pulse duration in the range of microsecond and millisecond is used. Long pulsed lasers are the examples. When this principle is used to target the tissue which doesn’t include chromophores, the laser is first absorbed to chromphore and the heat generated in the chromophore is transferred to surrounding target tissue. This is called “extended theory of SPTL”. 2. pulse duration is shorter than nsecond Recently picosecond lasers are invented and used for pigmentary lesion treatment. The pulse duration of picosecond laser is shorter than the nanosecond pulse duration fo Q switched lasers. Picosecond duration is related with high intensity mechanical injury of melanosomes and more efficiently destroys melanosomes into smaller pieces. 3. fluence is lower than Q switched laser When the fluence is lowered, the explosion of melanosome is not enough to destroy the melanocytes but enough to destroy melanosome itself. Destroying melanosomes and saving melanocytes are named “subcellular SPTL” because it targets subcellular organelle melanosomes. 4. wavelength is variable and pulse duration is longer than nsecond IPL can also be used for pigmentary lesion treatment. The difference from SPTL is IPL uses wide range of wavelength in one emission. Lasers use monochromatic pulse, IPL can be regarded as a combination of multiple lasers which have different wavelengths.

Basic laser principles for skin aging

여운철 ( Un Cheol Yeo ) 대한피부과학회 2017 대한피부과학회 학술발표대회집 Vol.69 No.2

아토피 피부염 환자 말초혈액 호중구에서 Superoxide Anion 생성의 측정

여운철(Un Cheol Yeo),김선훈(Seon Hoon Kim) 대한피부과학회 1990 大韓皮膚科學會誌 Vol.28 No.6

Atopic dermatitis is characterized by many signs of immunodeficiency. We have performed this experiment to know whether there are reduced respiratoty burst of neutrophils in patients with atopic dermatitis in response to stimulants such as zymosan activated serum(ZAS), phorbol myristate cetate(PMA) and for- mylmethionylleucylphenylalanine(FMLP). The atopic derrqatitis group consisted of 27 patients(5 are severe, 22 are mild) and the control group consisted of 10 persons. Superoxide anion generation of neutrophils in response to stimulants was measured as nmol of reriuced cytochrome C by spectrophotometer(at 550nm, molar extinction coefficient of cytochrome C=21.lmM 1cm ). We compared the superoxide anion generation according to the severity of atopie dermatitis, total serum IgE level and eosinophil count. Results were as follows. 1. After stimulation by PMA and FMLP, superoxide anion generation in severe atopic dermatitis group decreased compared with the control and mild atopic dermatitis group. After stimulation by ZAS there was a decreasing tendency in severe atopic dermatitis group, however it was not statistically significant. 2. Superoxide anion generation had no correlation with the total serum IgE level. 3. Superoxide anion generation had no correlation with the eosinophil count. Our data suggested that some physiologic stimulants of respiratory hurst may be generated during the course of atopic dermatitis. Possible physiologic stimulants include C5a, bacterial chemotactic factors, certain arachidonate metabolites such as leukotriene B4, as well as phagocytosis. We think that these physiologic stimulants can desensitize neutrophils of atopic dermatitis in vivo specifically or onspecifically so that superoxide anion generation may be reduced in response tostimulants in vitro. (Kor J Dermatol 28(B):B89 676, 1990)