Ethidium bromide as a marker of mtDNA replication in living cells.

Mitochondrial DNA (mtDNA) in tumor cells was found to play an important role in maintaining the malignant phenotype. Using laser scanning confocal fluorescence microscopy (LSCFM) in a recent work, we reported a variable fluorescence intensity of ethidium bromide (EB) in mitochondria nucleoids of living carcinoma cells. Since when EB is bound to nucleic acids its fluorescence is intensified; a higher EB fluorescence intensity could reflect a higher DNA accessibility to EB, suggesting a higher mtDNA replication activity. To prove this hypothesis, in the present work we studied, by LSCFM, the EB fluorescence in mitochondria nucleoids of living neuroblastoma cells, a model system in which differentiation affects the level of mtDNA replication. A drastic decrease of fluorescence was observed after differentiation. To correlate EB fluorescence intensity to the mtDNA replication state, we evaluated the mtDNA nascent strands content by ligation-mediated real-time PCR, and we found a halved amount of replicating mtDNA molecules in differentiating cells. A similar result was obtained by BrdU incorporation. These results indicate that the low EB fluorescence of nucleoids in differentiated cells is correlated to a low content of replicating mtDNA, suggesting that EB may be used as a marker of mtDNA replication in living cells. © 2012 Society of Photo-Optical Instrumentation Engineers (SPIE)

Crural ulcers at lower limbs: Acquired or genetic pathology?

The authors report a case of a 50-year-old man with bilateral, wide, crural ulcers of 1-year duration on the lower limbs. The patient experienced 3 transient ischemic attacks (TIAs), and instrumental exams revealed thrombotic events involving the kidney, lung, and central nervous system (CNS). The authors performed a thrombophilic screening, which indicated altered concentrations of C and S proteins and antithrombin III (AT III) and a single-base mutation (C677T) at the methylene tetrahydrofolate reductase gene (MTHFR). Methylene tetrahydrofolate reductase gene mutation may be associated with a coagulation system disorder. These data suggest that the MTHFR mutation may be responsible for cutaneous ulcer pathogenesis

Role of p53 in the Regulation of Cellular Senescence

The p53 transcription factor plays a critical role in cellular responses to stress. Its activation in response to DNA damage leads to cell growth arrest, allowing for DNA repair, or directs cellular senescence or apoptosis, thereby maintaining genome integrity. Senescence is a permanent cell-cycle arrest that has a crucial role in aging, and it also represents a robust physiological antitumor response, which counteracts oncogenic insults. In addition, senescent cells can also negatively impact the surrounding tissue microenvironment and the neighboring cells by secreting pro-inflammatory cytokines, ultimately triggering tissue dysfunction and/or unfavorable outcomes. This review focuses on the characteristics of senescence and on the recent advances in the contribution of p53 to cellular senescence. Moreover, we also discuss the p53-mediated regulation of several pathophysiological microenvironments that could be associated with senescence and its development

Association between severity of COVID-19 respiratory disease and risk of obstructive sleep apnea

Objectives: The purpose of this observational retrospective study was to evaluate, in patients with a severe acute respiratory syndrome coronavirus 2 infection, the association between the severity of coronavirus disease 2019 (COVID-19) respiratory illness and the risk of infected patients to develop obstructive sleep apnea (OSA). Methods: Ninety-six patients with confirmed COVID-19 infection were enrolled in the study. The STOP-BANG questionnaire to investigate the risk of the OSA syndrome was filled in by the patients at admission. The enrolled patients were divided into 2 groups according to the respiratory disease: group 1 (72 patients), hospitalized patients undergoing conventional oxygen therapy; group 2 (24 patients), patients requiring enhanced respiratory support. STOP-BANG results of these 2 groups were compared to observe whether patients with high OSA risk more frequently presented a severe form of COVID-19. Results: 41.6% of the patients in group 2 had a STOP-BANG score between 5 and 8 (high risk of having apnea); in contrast, 20.8% of the patients in group 1 had a STOP-BANG score between 5 and 8, with a statistically significant difference between the 2 groups (P ¼ .05). A complementary trend was observed regarding the proportion of patients in the range 0 to 2, which classifies patients at a low risk of OSA (48.6% vs 20.8% for groups 1 and 2, P ¼ .01). Conclusions: According to our data, the chances of having a severe case of COVID-19 should be considered in patients at high risk of OSA. Current Knowledge/Study Rationale: Emerging research suggests that OSA could represent a potentially important risk factor for the severe forms of COVID-19. The purpose of this observational retrospective study was to evaluate the potential association between OSA and the severity of COVID-19 disease. Study Impact: According to our data, the likelihood of contracting a severe form of COVID-19 disease should be considered in patients at high risk of OSA