Purpose: Skin ageing is marked by structural and functional changes in epidermis and dermis, which result clinically in wrinkles, loss of elasticity, and rough-textured appearance. In this context, different dermal fillers have been used to overcome these negative effects associated with skin ageing, such as hyaluronic acid (HA) and poly-L-lactic acid (PLLA). Despite their low immunogenicity, these materials can cause an inflammatory reaction after application. Materials and Methods: Considering high demand of HA and PLLA as filler material, this study aimed to evaluate their in vitro and in vivo effects. For the in vitro study, human dermal fibroblast cell cultures were supplemented with HA or PLLA for 24, 48, and 72 h. The following parameters were assayed: 1) cell proliferation, 2) cell viability, and 3) quantification of type I collagen by ELISA. For the in vivo study, HA or PLLA was injected in the dermis of Wistar rats and the tissues were collected after 15, 30, and 60 days for histologic evaluation and for quantification of type I collagen by Western blotting. The quantitative data were statistically analyzed using an ANOVA two-way. The significance level was set at 5%. Results: At 72 h, high cell proliferation was observed for HA compared to control (p< 0.05). Cultures exposed to PLLA exhibited a reduction in both cell proliferation and viability compared to control in all time points (p< 0.05). Type I collagen expression was greater in cultures exposed to HA or PLLA compared to control (p< 0.05). Histologic analysis showed the presence of multinucleated cells only in the PLLA group in all experimental time points. Western blotting analysis revealed high content of type I collagen in HA compared to PLLA (p< 0.05). Conclusion: The present study addresses a potentially unfavorable effect of dermal PLLA filler on the fibroblast phenotype, with possible clinical complications, unlike HA.

Background: L-arginine (Arg) is an amino acid that contributes to several aspects of human biochemistry. Individuals with malnutrition and certain physical conditions could benefit from arginine intake. However, as Arg is required by certain viruses, it is advised to avoid it in one's diet and supplementation during viral illnesses. New studies have emerged during the COVID-19 pandemic, and pioneering research has been reviewed. Main body of the The purpose of this review is to determine when and why Arg depletion, supplementation, or avoidance is advisable, considering the divergent results. A narrative review was conducted by surveying scientific publications indexed in electronic databases. Studies published from 1960 up to 2024, with no language restrictions, were included. Arg comes from proteins in the human diet. The kidney is the main site of endogenous Arg synthesis and also responsible for the overall metabolism of this amino acid, participating in synthesis, degradation and reabsorption. The liver can synthesize Arg, but since this is completely recycled in the urea cycle, it contributes little or no to the Arg plasma flux. Arg present in diet is passively absorbed in the small intestine and also transformed into urea and ornithine via urea cycle in hepatocytes. It is associated with macrophage metabolism, vasomotor control, intracellular signaling, memory formation, immune response, and an important messenger of the bronchopulmonary, cardiovascular and neural systems. Thus, excessive or decreased Arg concentration could impair health condition. High Arg concentrations stimulated rapid reactivation and resumption of protein synthesis in some viruses. Conclusion: According to research, caution should be exercised when supplementing or depleting the amino acid arginine. Individuals who are carriers of latent viruses, such as herpesviruses, and/or who have been exposed to other viruses studied, should avoid arginine supplements and the consumption of foods rich in arginine. However, as prophylaxis or antiviral therapy, control of arginine intake as well as the use of lysine supplements, its antagonist, is recommended for short periods starting after a possible viral exposure, or in face of stimuli that can remove viruses from their latent state and/or at the very beginning of the viral manifestation, in order to avoid a large viral multiplication and consequently control the infection. Long-term arginine depletion can significantly affect cellular metabolism and its use as supplemental therapy needs case-by-case evaluation. Graphical

The aim of this study was to test whether lyophilized conditioned media from human dental pulp mesenchymal stem cell cultures promote the healing of critical-size defects created in the calvaria of rats. Prior to the surgical procedure, the medium in which dental pulp stem cells were cultured was frozen and lyophilized. After general anesthesia, an 8 mm diameter bone defect was created in the calvaria of twenty-four rats. The defects were filled with the following materials: xenograft alone (G1) or xenograft associated with lyophilized conditioned medium (G2). After 14 or 42 days, the animals were euthanized, and the specimens processed for histologic and immunohistochemical analysis. Bone formation at the center of the defect was observed only in the G2 at 42 days. At both timepoints, increased staining for VEGF, a marker for angiogenesis, was observed in G2. Consistent with this, at 14 days, G2 also had a higher number of blood vessels detected by immunostaining with an anti-CD34 antibody. In conclusion, conditioned media from human dental pulp mesenchymal stem cell cultures had a positive effect on the regenerative process in rat critical-size bone defects. Both the formation of bone and enhancement of vascularization were stimulated by the conditioned media.