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Studies on Skin Diseases and Normal Skin Dobrev H. Mechanical properties in other dermatological diseases. In: Bioengineering of the skin: skin biomechanics. Elsner P., Berardesca E., Wilhelm K-P. (eds) CRC Press, Boca Raton, 2001: 215-228. Dobrev H. In vivo study of skin mechanical properties in Raynaud’s phenomenon. Skin Res Technol 2007, 13 (1): 91-94. Background/aim: Raynaud’s phenomenon is usually the first symptom in patients with systemic sclerosis and may precede skin changes by several months or years. Noninvasive measurements of skin elasticity are very sensitive and appropriate for objective and quantitative evaluation of sclerodermatous skin. The aim of this study was to investigate and compare the mechanical properties of the skin in patients with primary, secondary and suspected secondary Raynaud’s phenomenon. Materials/methods: A total of 63 patients were studied. They were classified as having scleroderma-type nailfold capillary abnormalities - 17 with indurative phase of scleroderma (Group 1), 9 with edematous phase of scleroderma (Group 2), 18 with suspected secondary Raynaud’s phenomenon (Group 3), and as having Raynaud’s phenomenontype nailfold capillary abnormalities - 19 with primary Raynaud’s phenomenon (Group 4). Thirty-nine sex- and age-matched healthy individuals with normal nailfold capillaroscopy pattern were also studied as controls. Mechanical properties of the skin were evaluated using a non-invasive suction device (Cutometer) equipped with a 2-mm probe. Measurements were performed over 5 anatomic regions: cheeks, volar forearms, wrists, hands and proximal phalanx of the fingers. The skin mechanical parameters analyzed were distensibility (Uf), elasticity (Ua/Uf) and viscoelasticity (Uv/Ue). Results: Most demonstrative changes were observed over volar forearms. Patients included in Group 1, Group 2 and Group 3 were characterized by significantly lower Uf and higher Uv/Ue compared to patient group 4 and controls. Patient groups 1 and 2 showed significantly lower Ua/Uf, as well. There were no significant differences in skin mechanical parameters between patient group 4 and control group. Conclusion: Mechanical properties of the skin in patients with suspected secondary Raynaud’s phenomenon significantly differ from these in patients with primary Raynaud’s phenomenon and resemble those in patients with edematous phase of scleroderma. Our findings suggest that the non-invasive measurements of skin elasticity could be helpful in identifying patients with Raynaud’s phenomenon at risk of developing systemic sclerosis. Dobrev H. Clinical and instrumental study of the efficacy of a new sebum control cream. J Cosmet Dermatol 2007 (in press) Dobrev H. CAPI TEXT v.1 – data analysis software for nailfold skin capillaroscopy. Folia Medica (Plovdiv) 2007 (in press) Dobrev H. Application of Cutometer area parameters for study human skin fatigue. Skin Res Technol 2005, 11 (2): 120-2. Background/aim The age-related decrease of skin elasticity results in bigger fatigue of adult skin than young skin after applying multiple stress at one and the same anatomic 2 region. The aim of this study was to compare the informativeness of cutometer standard R-parameters with new area-parameters regarding the age-related changes in human skin fatigue. Materials/methods A total of 40 healthy volunteers aged 12-82 years were studied. Mechanical parameters of the skin were determined using non-invasive suction skin elasticity meter (Cutometer). Measurements were made on temporal region and volar forearm. Skin mechanical parameters analyzed by Win-cutometer MPA software were R3, R4 and R9 (R-parameters), and F2 and F3 (area-parameters). Results The adult skin was characterized by significantly higher values of R4, R9 and F2, and lower F3 compared to young skin. R3 was not significantly altered. There were not any sex-related differences. F2 correlated positively with parameters R3, R4 and R9, while F3 correlated negatively with R4. A positive correlation within the parameters R3, R4 and R9 was established at both anatomic regions. Conclusion The non-invasive method applied can be useful for objective and quantitative investigation of age-related changes in skin fatigue and evaluation of the effects of cosmetic and antiaging topical products. The mechanical parameters R4 and F3 are most indicative of human skin fatigue. Dobrev H. Study of human skin mechanical properties by means of cutometer. [Review] Folia Med (Plovdiv) 2002, 44 (3): 1-5. Aim Cutometer is a commercially available non-invasive suction skin elasticity meter. The purpose of the present article is do discuss some aspects of the biological informativeness and interpretation of the results obtained under studying of skin mechanical properties with cutometer. Methods/Results Results of previously published in the literature studies on the mechanical properties of healthy and diseased skin and their changes after external influences are analyzed Conclusion The cutometer method of investigation gives an objective and meaningful information on the mechanical properties of healthy and diseased human skin. Dobrev H. In vivo study of skin mechanical properties in patients with systemic sclerosis. J Am Acad Dermatol 1999, 40 (3): 436-442. Background Measurements of skin elasticity are more sensitive than the skin severity score and appropriate for evaluation of sclerodermatous skin. Objective: Our purpose was to investigate the mechanical properties of the skin in patients with systemic sclerosis depending on the stage of the disease. Methods Seventeen patients, 8 with edematous phase and 9 with indurative phase of skin involvement, and 16 healthy subjects were studied. Clinical scoring of skin thickness and measurements of skin elasticity with a noninvasive suction device (Cutometer) were performed over 11 anatomic regions. Results Edematous phase was characterized by significantly lower immediate distension (Ue) and final distension (Uf), and higher viscoelastic to elastic ratio (Uv/Ue) of the skin compared with indurative phase, except for the forehead (8 mm probe). The changes in skin mechanical parameters for fingers were identical in both phases. Low values of skin distensibility correlated with severe skin thickness or hidebound skin. Results were influenced by body site and by the diameter of measuring probe used. 3 Conclusion The noninvasive method applied is suitable for objective and quantitative monitoring of skin involvement in patients with systemic sclerosis. Dobrev H. Value of the noninvasive skin bioengineering methods in patients with scleroderma. [Review] Rheumatology (Bulgaria) 1998, 6 (2): 15-17. Modern bioengineering methods provide an objective information regarding the degree of the skin involvement and disturbances of the microcirculation in systemic and localized sclerosis. They are characterized by noninvasiveness, that allows repeated measurements, and achieving quantitative data subjected to statistical analysis. The changes in skin thickness and density can be evaluated by high-frequency ultrasound, nuclear magnetic resonance and elastometry. Microangiopathy can be studied by capillaroscopy, laser-doppler flowmetry, measurements of transcutaneous oxygen tension, thermometry and thermography. Noninvasive skin bioengineering methods are useful in monitoring the therapy effect and disease progression in patients with scleroderma. Dobrev H. In vivo study of skin mechanical properties in Scleredema of Buschke. Acta Derm Venereol (Stockh) 1998, 78 (2): 103-106. A non-invasive, in vivo suction device was used to investigate the mechanical properties of the skin in a patient with scleredema of Buschke. Clinical scoring of skin induration and measurements of skin elasticity were performed over 9 anatomic regions on admission and after 3 (on discharge), 17 and 28 months. Immediate distension, final distension and immediate retraction were significantly decreased, while the viscoelastic to elastic ratio was significantly increased in the patient as compared to the healthy controls. Delayed distension and biological elasticity were preserved. Low values of skin distensibility correlated with a severe skin induration (p<0.001). The changes were more expressive with the 8 mm-diameter measuring probe than the 2 mm-diameter probe. The method applied can be used for objective and quantitative assessment of skin involvement in scleredema of Buschke. Grudeva-Popova J, H. Dobrev. Biomechanical measurement of skin distensibility in scleredema of Buschke associated with multiple myeloma. Clin Exp Dermatol 2000, 25 (3): 247-249. We report a case of scleredema of Buschke associated with IgG kappa monoclonal hypergammaglobulinaemia. After myeloma polychemotherapy an improvement in skin involvement was observed and confirmed by means of non-invasive skin elasticity measurements. This suggests a relationship between the two diseases. The bioengineering method used can be useful for early detection and monitoring the skin involvement in patients with this disease association. 4 Dobrev H. Scleroedema Buschke с 36 годишно протичане. [Scleredema of Buschke with a 36-year duration] 8ht Annual Sofia dermatological days, November 5-7, 1999, Sofia, Bulgaria. Dermatol Venereol (Bulgaria) 1999, 38 (2): 38. (Summary) Dobrev H. In vivo study of skin mechanical properties in psoriasis vulgaris. Acta Derm Venereol 2000, 80 (4): 263-266. The aim of this study was to investigate the mechanical properties of the skin in psoriatic plaques before and after treatment with dithranol and in clinically uninvolved psoriatic skin in comparison with the skin of healthy controls. In total, 82 psoriatic plaques in 19 inpatients and 51 age-matched control subjects were studied with a non-invasive suction device (Cutometer). The plaques were characterized by statistically significant lower skin distensibility and elasticity, and a higher viscoelastic to elastic ratio compared with adjacent apparently normal skin. Delayed distension and hysteresis measured using a 2mm diameter probe were decreased, but were increased when measured by a 8-mm diameter probe. These differences can be explained by the increased skin thickness in psoriasis and by the different aspects of skin mechanics determined by the 2 measuring probes. After treatment, the mechanical parameters of psoriatic plaques approached the values of adjacent control skin. The uninvolved volar forearm skin in psoriatic patients (2mm diameter probe) showed statistically significant lower values of skin distensibility and higher values of viscoelasticity parameters compared with the skin of healthy control subjects. This suggests that the normal-appearing psoriatic skin is not entirely normal. The non-invasive method applied can be used for objective and quantitative evaluation of the effect of therapy in patients with psoriasis. Dobrev H. Changes in epidermal water content in patients with psoriasis vulgaris. Scientific Researches of the Union of Scientists – Plovdiv. Series D. Medicine, Pharmacy and Stomatology, Vol. 1. (Plovdiv) 2002: 107-110. Aim The aim of this study was to determine the epidermal water content in lesional and perilesional psoriatic skin before and after treatment with dithranol. Materials and Methods. A total of 96 psoriatic plaques in 22 in-patients (4 women, 18 men, aged 27-82 years, with disease duration of 1-35 years and PASI score of 4.1-32.6) were studied. Epidermal hydration was determined by means of non-invasive skin capacitance meter (Corneometer CM 820, Courage+Khazaka, Cologne, Germany). Measurements were performed before and after 18±7-day treatment with dithranol. Results The average values of electrical capacitance of psoriatic plaques (n=96) and adjacent healthy skin were 29.8±9.4 АЕ and 64.1±11.5 АЕ, respectively (P<0.001). After treatment, the values of electrical capacitance of psoriatic plaques (n=54) increased from 27.2±8.7 АЕ to 40.2±14.0 АЕ (Р<0.001), while those of perilesional skin did not significantly change and were 63.5±11.3 and 64.9±11.9 АЕ, respectively. Conclusion Pathologic epidermis in psoriasis vulgaris is characterized by low water content, which increases after treatment with dithranol but remains lower than the water content of adjacent healthy skin. 5 Dobrev H. Use of cutometer to assess dermal oedema in erysipelas of the lower legs. Skin Res Technol 1998, 4 (3): 155-159. Background/Aims Inflammatory dermal oedema in erysipelas alters skin mechanics. The aims of this study were to determine the relationship between the skin mechanical properties and the changes in dermal water content in patients with erysipelas of the lower leg, and to assess the value of measuring skin elasticity in monitoring the effect of therapy. Patients/Methods Twenty-five in-patients were studied before the treatment and after 10 and 20 days. Visual scoring of oedema, measurements of limb circumference and skin elasticity with a non-invasive, suction device (Cutometer) were made on the affected and unaffected lower legs. Results Indurated skin was characterized by raised delayed distension (Uv), final distension (Uf), resilient distension (R), viscoelastic to elastic ratio (Uv/Ue) and hysteresis (H) and lower immediate distension (Ue), immediate retraction (Ur), gross elasticity (Ua/Uf) and biological elasticity (Ur/Uf). The visual score of oedema and leg circumference significantly correlated with the increase in Uv, Uv/Ue and H and the decrease in Ua/Uf and Ur/Uf. The large 8 mm diameter measuring probe produced more pronounced changes than the small 2 mm probe. As a result of treatment, a significant reduction in viscoelastic parameters (Uv, Uv/Ue, R, H) and an increase in elastic parameters (Ua/Uf, Ur/Uf) was observed. Conclusion The non-invasive method applied is suitable for objective assessment of dermal oedema and disease evolution in patients with erysipelas. Dobrev H. Comparative study of the skin mechanical properties in erysipelas of the lower legs using suction method and share wave propagation method. 13th Congress European Academy of Dermatology & Venereology (EADV), November 1721, 2004, Florence, Italy. Background/aim Inflammatory dermal edema in erysipelas alters skin mechanics. The aim of this study was to compare the informativeness of two different methods for evaluation of skin mechanical properties. Methods Ten in-patients were studied prior to and after the treatment. Skin viscoelasticity was evaluated on the affected and unaffected lower legs using a suction device (Cutometer) equipped with two probes and resonance running time measurements (RRTM) using the Reviscometer. Results Affected skin was characterized by significantly lower cutometer elastic Rparameters (Ur, Ua/Uf and Ur/Uf), higher viscoelastic R-parameters (Uv, Uv/Ue, R8 and hysteresis) and higher area-parameters (F0, F2 and F4). After treatment, the indicated parameters significantly changed toward to those of the normal skin. The 8 mm-diameter cutometer probe produced more pronounced changes than the smaller 2 mm-diameter probe. The initial RRTM values were similar on both lower legs. The treatment induced a significant decrease in multidirectional RRTM on the affected skin (-10.8%) which is due to the marked decrease in the minimum RRTM (-20.3%). The last indicates an increase in shear wave velocity predominantly in the direction of skin tension lines, i.e., increased intrinsic tension inside the skin, and suggest an improvement of skin elasticity. Conclusion Simultaneously measurements of skin mechanical properties by means of suction method and shear wave propagation method are useful tool for objective evaluation of the skin changes in patients with erysipelas. Acknowledgement: The author would like to thank Courage+Khazaka Electronic, Köln, Germany for supplying with the Cutometer MPA 580 and Reviscometer RVM 600. 6 Dobrev H. Syndroma Ehlers-Danlos - механични свойства на кожата. [Syndroma Ehlers-Danlos – mechanical properties of the skin] Xht Annual Sofia dermatological days, November 2-3, 2001, Sofia, Bulgaria. Dermatol Venereol (Bulgaria) 2001, 40 (2): 27. (Summary) Dobrev H. Fasciitis eosinophilica - механични свойства на кожата. [Fasciitis eosinophilica – mechanical properties of the skin] Xht Annual Sofia dermatological days, November 2-3, 2001, Sofia, Bulgaria. Dermatol Venereol (Bulgaria) 2001, 40 (2): 28. (Abstract) Dobrev H. Study of human skin mechanical properties by means of cutometer. [Review] Folia Med (Plovdiv) 2002, 44 (3): 1-5. Aim Cutometer is a commercially available non-invasive suction skin elasticity meter. The purpose of the present article is do discuss some aspects of the biological informativeness and interpretation of the results obtained under studying of skin mechanical properties with cutometer. Methods/Results Results of previously published in the literature studies on the mechanical properties of healthy and diseased skin and their changes after external influences are analyzed Conclusion The cutometer method of investigation gives an objective and meaningful information on the mechanical properties of healthy and diseased human skin. Dobrev H. Study of human skin fatigue. Scientific Researches of the Union of Scientists – Plovdiv. Series D. Medicine, Pharmacy and Stomatology, Vol. 2. (Plovdiv) 2003: 84-87. Aim The aim of this study was to determine the age-related changes in skin fatigue. Materials/Methods A total of 40 healthy volunteers aged 12-82 years was studied. They were divided into 4 groups: 10 young men (mean age of 18.7±5.4 years), 10 young women (mean age of 20.7±5.5 years), 10 elderly men (mean age of 70.9±7.2 years) and 10 elderly women (67.8±6.8 years). Measurements were made on the right temporal region and volar forearm by means of a non-invasive suction skin elasticity meter (Cutometer SEM 474, Courage+Khazaka, Cologne, Germany). We used a 2 mm-diameter measuring probe and applied a constant suction of 400 mbar for 1 s followed by relaxation time of 1 s, 30 repetitions. Eight skin mechanical parameters were analyzed. Results At the two anatomical regions aged skin showed statistically significant higher values of the mechanical parameters R1, R4, R3-R0, R4-R1, R0-(R3-R10) and significantly lover values of the parameters R0-R1, R3-R4, R3-R10 compared to young skin. There were not established any sex-related differences. Conclusion Skin aging induces progressive decrease in the skin capability to restore its initial shape after multiple deformations, i.e. the aged skin is characterized by greater fatigue than young skin. 7 Dobrev H. Application of Cutometer area parameters for study human skin fatigue. II. Spring Symposium of the European Academy of Dermatology and Venereology (EADV), April 29 – May 1, 2004, Budapest, Hungary. J Eur Acad Dermatol Venerol 2004, 18, Suppl.1: 53. Background/aim The age-related decrease of skin elasticity results in bigger fatigue of adult skin than young skin after applying multiple stress at one and the same anatomic region. The aim of this study was to compare the informativeness of cutometer standard R-parameters with new area-parameters regarding the age-related changes in human skin fatigue. Materials/methods A total of 40 healthy volunteers aged 12-82 years were studied. Mechanical parameters of the skin were determined using non-invasive suction skin elasticity meter (Cutometer). Measurements were made on temporal region and volar forearm. Skin mechanical parameters analyzed by Win-cutometer MPA software were R3, R4 and R9 (R-parameters), and F2 and F3 (area-parameters). Results The adult skin was characterized by significantly higher values of R4, R9 and F2, and lower F3 compared to young skin. R3 was not significantly altered. There were not any sex-related differences. F2 correlated positively with parameters R3, R4 and R9, while F3 correlated negatively with R4. A positive correlation within the parameters R3, R4 and R9 was established at both anatomic regions. Conclusion The non-invasive method applied can be useful for objective and quantitative investigation of age-related changes in skin fatigue and evaluation of the effects of cosmetic and antiaging topical products. The mechanical parameters R4 and F3 are most indicative of human skin fatigue. Dobrev H. Photoaging and skin elasticity. Research Reports of the Union of Scientists in Bulgaria – Plovdiv. Annual, Series B. Natural Sciences and Humanities, Vol. 1. (Plovdiv) 2000: 117-120. The aim of the present study was to determine the effect of chronic sun exposure on the skin mechanical properties. We studied 73 volunteers (37 men, 36 women, aged range 10-79 years, mean age 41 years) by means of a noninvasive suction skin elasticity meter (Cutometer). Sun-exposed skin of the dorsal forearm showed a significantly lower distensibility and biological elasticity than the unexposed volar forearm skin. These changes are related to the massive increase and disorganization of the elastic tissue, which are accompanied by lost of functional elastic fibers. The later plays an important role in maintaining the collagen fiber network, in controlling the movements of this network within the ground substance and in restoring the initial position of the skin after deformation. On both anatomical regions skin elasticity decreased and viscoelasticity increased with the age. Dobrev H. Age related changes in the mechanical properties of human skin. Dermatol Venereol (Bulgaria) 1999, 38 (2): 21-25. We used a non-invasive, in vivo suction skin elasticity meter to investigate age-related skin mechanical properties on 12 anatomic regions. A total of 40 volunteers was studied consisting of 10 young males, 10 old males, 10 young females and 10 young males. The parameters determined were Ue, immediate distension; Uv, delayed distension; Uf, final 8 distension; Ur, immediate retraction; Ua, final retraction; R, residual deformation and their relations Ua/Uf, brut elasticity; Ur/Ue, net elasticity; Ur/Uf, biological elasticity; Uv/Ue, viscoelastic to elastic ratio and H, hysteresis. Aged skin was characterized by significantly lower elastic parameters (Ue, Uf, Ur, Ua/Uf, Ur/Ue, Ur/Uf) and higher viscoelastic parameters (Uv, Uv/Ue, H, R). On all the anatomic regions, the decrease in skin elasticity and the increase in skin viscoelasticity significantly correlated with the age. The changes were more pronounced on the sun-exposed sites. There were no sex differences. The method used is suitable for investigation of aging process and efficacy of topical preparations applied.