Key Factors in the Complex and Coordinated Network of Skin Keratinization: Their Significance and Involvement in Common Skin Conditions.

The epidermis serves many vital roles, including protecting the body from external influences and healing eventual injuries. It is maintained by an incredibly complex and perfectly coordinated keratinization process. In this process, desquamation is essential for the differentiation of epidermal basal progenitor cells into enucleated corneocytes, which subsequently desquamate through programmed death. Numerous factors control keratinocyte differentiation: epidermal growth factor, transforming growth factor-α, keratinocyte growth factor, interleukins IL-1-ß and IL-6, elevated vitamin A levels, and changes in Ca2+ concentration. The backbone of the keratinocyte transformation process from mitotically active basal cells into fully differentiated, enucleated corneocytes is the expression of specific proteins and the creation of a Ca2+ and pH gradient at precise locations within the epidermis. Skin keratinization disorders (histologically characterized predominantly by dyskeratosis, parakeratosis, and hyperkeratosis) may be categorized into three groups: defects in the α-helical rod pattern, defects outside the α-helical rod domain, and disorders of keratin-associated proteins. Understanding the process of keratinization is essential for the pathogenesis of many dermatological diseases because improper desquamation and epidermopoiesis/keratinization (due to genetic mutations of factors or due to immune pathological processes) can lead to various conditions (ichthyoses, palmoplantar keratodermas, psoriasis, pityriasis rubra pilaris, epidermolytic hyperkeratosis, and others).

Increased Scabies Incidence at the Beginning of the 21st Century: What Do Reports from Europe and the World Show?

Reports from various countries have described increasing numbers of scabies cases, especially in the past two decades. The epidemiological data for various world regions showed prevalence estimates ranging from 0.2% to 71%, with the highest prevalence in the Pacific region and Latin America. Therefore, geographically, scabies occurs more commonly in the developing world, tropical climates, and in areas with a lack of access to water. According to results from specific regions of the world, the greatest burdens from scabies were recorded for East Asia, Southeast Asia, Oceania, tropical Latin America, and South Asia. Among countries with the highest rates, the top 10 were Indonesia, China, Timor-Leste, Vanuatu, Fiji, Cambodia, Laos, Myanmar, Vietnam, and the Seychelles. From Europe, available data shows an increasing trend in scabies infestation, particularly evident among populations with associated contributing factors, such as those who travel frequently, refugees, asylum seekers, those who regularly lack drinking water and appropriate hygiene and are of a younger age, etc. This increase in observed cases in the last 10-20 years has been evidenced by research conducted in Germany, France, Norway, and Croatia, among other countries. In addition, increased scabies transmission was also recorded during the COVID-19 pandemic and may have been the result of increased sexual intercourse during that time. Despite all the available treatment options, scabies commonly goes unrecognized and is therefore not treated accordingly. This trend calls for a prompt and synergistic reaction from all healthcare professionals, governmental institutions, and non-governmental organizations, especially in settings where population migration is common and where living standards are low. Furthermore, the proper education of whole populations and accessible healthcare are cornerstones of outbreak prevention. Accurate national data and proper disease reporting should be a goal for every country worldwide when developing strategic plans for preventing and controlling the community spread of scabies.

Recent information on photoaging mechanisms and the preventive role of topical sunscreen products.

The main environmental element causing photoaging is ultraviolet (UV) light, and this involves an extrinsic mechanism of skin aging superimposed on an intrinsic process. Clinical (evident) characteristics of photoaging include the presence of deep wrinkles, deterioration of skin laxity, and hyperpigmentation. In the UV light spectrum, UVA and UVB radiation cause the most damage in photoaging. UVB light has shorter wavelengths and is mostly absorbed by the stratum corneum, causing erythema and changes in the epidermis, whereas UV rays with longer wavelengths (i.e., UVA) penetrate to the deepest layer of the skin (i.e., the dermis) and interact with DNA. As a result of UV radiation, chemical reactions in the skin produce reactive oxygen species (ROS), which cause protein denaturation, impairment of RNA and DNA synthesis, and damage to the skin structure. Using local sunscreen agents can not only prevent sunburn, but also help prevent photocarcinogenesis and photoaging. Therefore, many epidemiological studies have been conducted with results showing credible and positive evidence for the safety and efficacy of sunscreen to prevent photoaging and photocarcinogenesis.