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Emerging Diseases
Published in Gary S. Moore, Kathleen A. Bell, Living with the Earth, 2018
Gary S. Moore, Kathleen A. Bell
The disease: The GAS produce a variety of diseases that include strep throat, impetigo, and scarlet fever. Occasionally, the strep invade deeper tissues such as blood, lungs, or even fat and muscles. The more severe of these invasions results in necrotizing fasciitis and/or streptococcal toxic shock syndrome. The popular media characterized the strep that caused necrotizing fasciitis as “flesh-eating bacteria” because of their ability to produce a progressing destructive infection of the underlying tissues. Streptococcal toxic shock syndrome is caused by a highly invasive strep that produces shock and injury to internal organs such as the kidneys, liver, and lungs. Necrotizing fasciitis usually begins with a trivial or even unnoticed trauma that appears in 24 hours as a lesion with swelling and redness. This is a deep-seated infection of the subcutaneous tissue that progressively destroys the underlying connective tissue and fat while sometimes sparing the skin and muscle. The early signs and symptoms of necrotizing fasciitis include fever, severe pain and swelling, and erythema (redness) at the site of the wound. The wound deeply colors to blue with blisters that contain a clear yellow fluid. Within 4–5 days, the purple areas become gangrenous, and at 7–20 days, dead skin separates at the margins of infection revealing marked necrosis of the underlying subcutaneous tissue. In a few cases, this process quickly escalates until several large areas of gangrenous skin and the patient may become dull and unresponsive due to the toxins in his/her system. Many of the present GAS cases of necrotizing fasciitis inevitably lead to severe systemic illness with high morbidity even in otherwise healthy patients who receive extensive support in the form of antibiotics, dialysis, and surgical techniques.150 These recent developments along with the increased mortality from GAS suggest the emergence of a more virulent streptococcus.151
Extracting the elasticity of the human skin in microscale and in-vivo from atomic force microscopy experiments using viscoelastic models
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2021
Sahba Iravanimanesh, Mohammad Ali Nazari, Fereshteh Jafarbeglou, Mohammad Mahjoob, Mojtaba Azadi
Skin elasticity is one of the significant features of a healthy skin and skin’s ability to get back to initial form after being pulled (Kalra and Lowe 2016). For instance, in a disease called psoriasis, skin loses its normal elasticity and resilience, and becomes bruised, and cracked. The patients often have to use bland ointments and descaling agents to restore the normal mechanical functions of the skin (Jemec 2001). Skin mechanics can be potentially help in detection of such diseases and also many other skin disorders such as scleroderma, morphea, radio dermatitis, elastolysis (Agache and Humbert 2004). Furthermore, knowing the skin mechanics can be very useful in many cosmetic applications. For example, in order to prevent ageing, it is important for cosmetic surgeons to maintain the skin elasticity by using a variety of and invasive methods (Vlasblom 1967). Moreover, different parameters which cause aging such as ultraviolet radiation can be analyzed using skin mechanics through the stress-strain relationship (Oba and Edwards 2006). In addition, knowledge of mechanical properties of skin is essential to replicate a biologically relevant artificial skin that would serve a wide range of applications. These applications include the development of artificial outer skin to substitute animal as well as clinical testing for evaluating drugs, cosmetics and other consumer products (Geerligs 2010). Artificial skins are also used in graft surgery in skin transplantation to treat extensive wounds, trauma, burns, or areas of extensive skin loss due to infection such as necrotizing fasciitis or purpura fulminans (Steven and Schulz 2018). Artificial skin that mimic the mechanical properties of natural skin are also useful for cancer patients whose cancerous skin are removed (Wikipedia 2018). Furthermore, a reliable estimate of skin mechanical properties can be used for biomedical devices to calibrate the elasticity of bio-sensors for measuring skin stretch induced motion artifacts (Kalra and Lowe 2016). The knowledge of mechanical properties of skin during different periods of a disease is necessary to better design robotic tele-surgery equipment as in laparoscopic surgery (Westebring et al. 2008). The skin modifier often serves as a reconstituting agent to restore the elastic and supple of skin in areas that different factors has altered its mechanical properties (Jemec 2001).