Raja Dahmane

Free Radicals and Extrinsic Skin Aging

Human skin is constantly directly exposed to the air, solar radiation, environmental pollutants, or other mechanical and chemical insults, which are capable of inducing the generation of free radicals as well as reactive oxygen species (ROS) of our own metabolism. Extrinsic skin damage develops due to several factors: ionizing radiation, severe physical and psychological stress, alcohol intake, poor nutrition, overeating, environmental pollution, and exposure to UV radiation (UVR). It is estimated that among all these environmental factors, UVR contributes up to 80%. UV-induced generation of ROS in the skin develops oxidative stress, when their formation exceeds the antioxidant defence ability of the target cell. The primary mechanism by which UVR initiates molecular responses in human skin is via photochemical generation of ROS mainly formation of superoxide anion (O2 − ∙), hydrogen peroxide (H2O2), hydroxyl radical (OH∙), and singlet oxygen (1O2). The only protection of our skin is in its endogenous protection (melanin and enzymatic antioxidants) and antioxidants we consume from the food (vitamin A, C, E, etc.). The most important strategy to reduce the risk of sun UVR damage is to avoid the sun exposure and the use of sunscreens. The next step is the use of exogenous antioxidants orally or by topical application and interventions in preventing oxidative stress and in enhanced DNA repair.

The Role of Antioxidants in Skin Cancer Prevention and Treatment

Skin cells are constantly exposed to reactive oxygen species (ROS) and oxidative stress from exogenous and endogenous sources. UV radiation is the most important environmental factor in the development of skin cancer and skin aging. The primary products caused by UV exposure are generally direct DNA oxidation or generation of free radicals which form and decompose extremely quickly but can produce effects that can last for hours, days, or even years. UV-induced generation of ROS in the skin develops oxidative stress when their formation exceeds the antioxidant defense ability. The reduction of oxidative stress can be achieved on two levels: by lowering exposure to UVR and/or by increasing levels of antioxidant defense in order to scavenge ROS. The only endogenous protection of our skin is melanin and enzymatic antioxidants. Melanin, the pigment deposited by melanocytes, is the first line of defense against DNA damage at the surface of the skin, but it cannot totally prevent skin damage. A second category of defense is repair processes, which remove the damaged biomolecules before they can accumulate and before their presence results in altered cell metabolism. Additional UV protection includes avoidance of sun exposure, usage of sunscreens, protective clothes, and antioxidant supplements.

Skin Photoaging and the Role of Antioxidants in Its Prevention

Photoaging of the skin depends primarily on the degree of ultraviolet radiation (UVR) and on an amount of melanin in the skin (skin phototype). In addition to direct or indirect DNA damage, UVR activates cell surface receptors of keratinocytes and fibroblasts in the skin, which leads to a breakdown of collagen in the extracellular matrix and a shutdown of new collagen synthesis. It is hypothesized that dermal collagen breakdown is followed by imperfect repair that yields a deficit in the structural integrity of the skin, formation of a solar scar, and ultimately clinically visible skin atrophy and wrinkles. Many studies confirmed that acute exposure of human skin to UVR leads to oxidation of cellular biomolecules that could be prevented by prior antioxidant treatment and to depletion of endogenous antioxidants. Skin has a network of all major endogenous enzymatic and nonenzymatic protective antioxidants, but their role in protecting cells against oxidative damage generated by UV radiation has not been elucidated. It seems that skins antioxidative defence is also influenced by vitamins and nutritive factors and that combination of different antioxidants simultaneously provides synergistic effect.

Vascular lasers and IPLS: Guidelines for care from the European Society for Laser Dermatology (ESLD)

Dermatology and dermatologic surgery have rapidly evolved during the last two decades thanks to the numerous technological and scientific acquisitions focused on improved precision in the diagnosis and treatment of skin alterations. Given the proliferation of new devices for the treatment of vascular lesions, we have considerably changed our treatment approach. Lasers and non‐coherent intense pulse light sources (IPLS) are based on the principle of selective photothermolysis and can be used for the treatment of many vascular skin lesions. A variety of lasers has recently been developed for the treatment of congenital and acquired vascular lesions which incorporate these concepts into their design. The list is a long one and includes pulsed dye (FPDL, APDL) lasers (577 nm, 585 nm and 595 nm), KTP lasers (532 nm), long pulsed alexandrite lasers (755 nm), pulsed diode lasers (in the range of 800 to 900 nm), long pulsed 1064 Nd:YAG lasers and intense pulsed light sources (IPLS, also called flash‐lights or pulsed light sources). Several vascular lasers (such as argon, tunable dye, copper vapour, krypton lasers) which were used in the past are no longer useful as they pose a higher risk of complications such as dyschromia (hypopigmentation or hyperpigmentation) and scarring. By properly selecting the wavelength which is maximally absorbed by the target – also called the chromophore (haemoglobin in the red blood cells within the vessels) – and a corresponding pulse duration which is shorter than the thermal relaxation time of that target, the target can be preferentially injured without transferring significant amounts of energy to surrounding tissues (epidermis and surrounding dermal tissue). Larger structures require more time for sufficient heat absorption. Therefore, a longer laser‐pulse duration has to be used. In addition, more deeply situated vessels require the use of longer laser wavelengths (in the infrared range) which can penetrate deeper into the skin. Although laser and light sources are very popular due to their non‐invading nature, caution should be considered by practitioners and patients to avoid permanent side effects. These guidelines focus on patient selection and treatment protocol in order to provide safe and effective treatment. Physicians should always make the indication for the treatment and are responsible for setting the machine for each individual patient and each individual treatment. The type of laser or IPLS and their specific parameters must be adapted to the indication (such as the vessels characteristics, e.g. diameter, colour and depth, the Fitzpatrick skin type). Treatments should start on a test patch and a treatment grid can improve accuracy. Cooling as well as a reduction of the fluence will prevent adverse effects such as pigment alteration and scar formation. A different number of repeated treatments should be done to achieve complete results of different vascular conditions. Sunscreen use before and after treatment will produce and maintain untanned skin. Individuals with dark skin, and especially tanned patients, are at higher risk for pigmentary changes and scars after the laser or IPLS treatment.

Skin and antioxidants

Abstract It is estimated that total sun exposure occurs non-intentionally in three quarters of our lifetimes. Our skin is exposed to majority of UV radiation during outdoor activities, e.g. walking, practicing sports, running, hiking, etc. and not when we are intentionally exposed to the sun on the beach. We rarely use sunscreens during those activities, or at least not as much and as regular as we should and are commonly prone to acute and chronic sun damage of the skin. The only protection of our skin is endogenous (synthesis of melanin and enzymatic antioxidants) and exogenous (antioxidants, which we consume from the food, like vitamins A, C, E, etc.). UV-induced photoaging of the skin becomes clinically evident with age, when endogenous antioxidative mechanisms and repair processes are not effective any more and actinic damage to the skin prevails. At this point it would be reasonable to ingest additional antioxidants and/or to apply them on the skin in topical preparations. We review endogenous and exogenous skin protection with antioxidants.

Anatomy and Surgical Relevance of Rouviere’s Sulcus

Rouvieres sulcus (RS) (i.e., incisura hepatis dextra, Gans incisura) represents an important anatomical landmark. The aim of the study was to determine the frequency of the RS, its description, its location, its relations to the right portal pedicle and to the plane of the common bile duct, and the evaluation of the surgical relevance of the obtained data. Forty macroscopically healthy and undamaged livers were removed during autopsies from cadavers of both sexes. The RS was present in 82% of the cases and in these the open RS was identified in 70% of the livers. The fused type was observed in 12% of the cases; 18% of the livers had no sulcus. The mean length of the open type RS was 28 ± 2 mm (range 24–32 mm) and its mean depth was 6 ± 2 mm (range 4–8 mm). The right posterior sectional pedicle was found in the RS in 70% of the cases. In 5% of the livers, we also dissected a branch of the anterior sectional pedicle. Inside 25% of the RS, we found the vein of segment 6. The RS identification may avoid bile duct injury during laparoscopic cholecystectomy and enables elective vascular control during the right liver resection.

Retracted: Muscles within muscles: a tensiomyographic and histochemical analysis of the normal human vastus medialis longus and vastus medialis obliquus muscles

The aim of this study was to show the connection between structure (anatomical and histochemical) and function (muscle contraction properties) of vastus medialis obliquus (VMO) and vastus medialis longus (VML). The non‐invasive tensiomyography (TMG) method was used to determine the contractile properties (contraction time; Tc) of VML and VMO muscle, as a reflection of the ratio between the slow and fast fibers in two groups of nine young men. VML and VMO significantly (P < 0.01) differ in the proportion of type 1 (59.6: 44%) and type 2b (6.3: 15%) fibers. The VML muscle is almost entirely composed of type 1 and type 2a fibers. In many samples of this muscle no type 2b fibers were found. The proportion of slow‐twitch type 1 fibers is nearly twice as high as the proportion of fast‐twitch type 2a fibers. These observations indicate that VML is a slower and more fatigue‐resistant muscle than VMO muscle. These characteristics correspond to the different functions of the VML, which is an extensor of the knee, and to the VMO, which maintains the stable position of the patella in the femoral groove. Our results obtained by TMG provided additional evidence that muscle fibers within the segments of VM muscle were not homogenous with regard to their contractile properties, thereby confirming the histochemical results. Tc can be attributed to the higher percentage of slow‐twitch fibers – type 1. The statistically shorter Tc (P ≤ 0.001) of VMO (22.8 ± 4.0 ms) compared with VML (26.7 ± 4.0 ms) in our study is consistent with previously found differences in histochemical, morphological and electrophysiological data. In conclusion, the results of this study provide evidence that the VML and VMO muscles are not only anatomically and histochemically different muscles, but also functionally different biological structures.

The influence of the sleeping on the formation of facial wrinkles

Abstract Objective: The study addressed the influence of sleep as an important but overlooked contributory factor to the formation and progression of facial wrinkles and an alternative pillow was designed to reduce them. Materials and methods. Fifteen healthy young participants of both sexes (aged 26–42 years) volunteered for this study. We used a transparent PVC pillow filled with air to demonstrate mechanical forces and deformations of the face as a consequence of sleeping on a pillow. We used a Podometer (PDMTR) (integrated fluorescent luminaire lamp) as a diagnostic device to visualize and to document the imprint of facial deformities on a glass, as seen during sleeping. Results. We observed various facial deformities and wrinkles during sleep (‘crow’s feet’ fine lines, lines around the mouth, flattening of the forehead, blunting of the nasofrontal angle, melolabial and nasolabial folds) and design an alternative pillow to reduce them by redistributing the pressure from the wrinkling parts of the face.

Anatomy of the ligamentum venosum arantii and its contribution to the left hepatic vein and common trunk control. A study on cadaveric livers.

Background: The control of the left hepatic vein (LHV) and the common trunk of the middle hepatic vein (MHV) and LHV (CT) is considered difficult during liver resection and could be improved by detailed knowledge on the ligamentum venosum Arantii (LV). Aim: The aim of this study was to describe the LV and its connections to the LHV and the CT and to present surgical relevance of the obtained data. Material and Methods: During autopsy of 50 cadavers of both sexes, the LV was exposed, measured and then dissected, simulating a surgical maneuver to facilitate the approach to the LHV and CT. The extrahepatic parts of the LHV, MHV and CT were measured. Results: The LV was 52–70 mm long and 5–8 mm thick. It had a fibrotic structure and was not patent in 96% of the cases. The extrahepatic part of the LHV measured 3–19 mm, that of the MHV 3–18 mm and that of the CT 4–15 mm. Conclusion: LV dissection facilitated extraparenchymatous clamping of the hepatic veins: the extrahepatic parts of the LHV and CT measured >3 mm in 86 and 84% of the cases, respectively.

The Influence of Different Elbow Angles on the Twitch Response of the Biceps Brachii Muscle Between Intermittent Electrical Stimulations

Srdjan Djordjevic1,3, Saso Tomažic2, Gregor Zupancic1, Rado Pisot3 and Raja Dahmane4 1Department of Biology, Biotechnical Faculty, University of Ljubljana, Ljubljana, 2Department of Telecommunications, Faculty of Electrical Engineering, University of Ljubljana, Ljubljana, 3Institute for Kinesiology Research, Science and Research Center of Koper, University of Primorska, Koper, 4Medical Faculty, Institute of Anatomy, University of Ljubljana, Ljubljana, Slovenia