Coronavirus Disease (COVID-19) is caused by the RNA virus SARS-CoV-2. The primary receptor for the virus is most likely Angiotensin-converting enzyme 2 (ACE2), and the virus enters the body by infecting epithelial cells of the respiratory tract. Through the activation of Toll Like Receptors (TLRs), epithelial cells begin to synthesize various biologically active molecules. The pathophysiology of the COVID 19 is primarily attributed to the hyperactivation of host's immune system due to direct damage to the cells, with consequent release of proinflammatory substances, but also due to the activation of the innate immune response through the activation of alveolar macrophages and dendrite cells (DC). A strong proinflammatory reaction causes damage to alveolar epithelial cells and vascular endothelium. Respiratory epithelial cells, alveolar macrophages and DC are likely to be the most important cells involved in the innate immune response to the virus, since prolonged and excessive SARS-CoV-2-induced activation of these cells leads to the secretion of cytokines and chemokines that massively attract leukocytes and monocytes to the lungs and cause lung damage.

Introduction: Elastic fibers are constituents of the dermal extracellular matrix, determining the histoarchitecture of the
dermal connective tissue. Organization and density of elastic fibers change as skin ages. The aim of this paper was to determine the similarities and differences between the photo-aging and the physiological aging of skin by examining organization and quantifying the elastic fibers in the dermis during aging. The material included samples of photoexposed and photoprotected skin, obtained from 90 cadavers aged 0-82 years. The samples were classified into five age groups: newborns, young age, middle age, mature age and the oldest age. Skin samples were stained using the Halmi modification of Aldehyd fucshin staining method, as well as Alcian blue staining (the Spicer method). Volume density (VD) of the elastic fibers was measured using Image J program.

Results: In the skin of newborns and young age group (neck and abdomen) elastic fibers appeared to form a network structure. In the photoexposed skin of the mature age and the oldest group, elastic fibers showed tendency to fragment, while the elastic material exhibited tendency to accumulate. VD of elastic network in the skin of the neck in the middle, mature and the oldest age group was greater than VD of abdominal skin of the respective age groups (3.66±0.28%, 5.61±0.22%, 6.24±0.21% respectively). Age-related statistically significant increase in VD of the elastic network in the skin of the neck, as well as a statistically significant reduction of elastic network VD in the abdominal skin, has been observed (middle age - oldest).

Conclusion: Correlation of the organization and quantity of elastic fibers with age exhibits different pattern in photoexposed compared to photoprotected skin. A quantitative evaluation of the volume density of elastic fibers correlates with clinically visible signs of photo-aging, primarily with solar elastosis.

Parodontopathy is a complex disease of periodontal tissues. The patological changes that occure here are destructive and lead to gradual or progressive periodontium disease and its anatomical and functional desintegration. The aim of the research was to use the PCR method (Polimerase Chain Reaction) to identify the presence and spreading of the oral pathogen Actinobacillus actinomycetemcomitans in subgingival plaque in patients suffering from the agressive parodontopathy and then compare it to qualitative-quantitaive structure of dental plaque in patients suffering from chronic parodontopathy. The study included 70 patients, average age of 45. The identification of microorganisms in subgingival plaque was determined by PCR method. In order to comfirm the diagnosis and determine the extent of destruction of periodontal tissue the standar epidemiological criteria were used: plaque index (Silness-Lӧe), gingival index (Lӧe-Silness), SBI index (Mühleman-Son) and DPP. Extremely high statictical significance of presence of A. actinomycetemcomitans was obtained in patients with agressive parodontopathy. The presence of A. actinomycetemcomitans and P. gingivalis showed the difference in distribution in patients with chronic as well as in patients with agressive pardontopathy. In our sample A.a was detected in a high percentage of younger patients with the diagnosis of agressive parodontopathy. Higher rate of A. actinomycetemcomitans in subgingival plaque has a direct impact on the course of parodontopathy. Its detection may be a useful marker for identifying the icreased risk for developing agressive parodontopathy in patients of younger population.