Hyperoxia and brain: the link between necessity and injury from a molecular perspective.

Oxygen (O2) supplementation is commonly used to treat hypoxia in patients with respiratory failure. However, indiscriminate use can lead to hyperoxia, a condition detrimental to living tissues, particularly the brain. The brain is sensitive to reactive oxygen species (ROS) and inflammation caused by high concentrations of O2, which can result in brain damage and mitochondrial dysfunction, common features of neurodegenerative disorders. Hyperoxia leads to increased production of ROS, causing oxidative stress, an imbalance between oxidants and antioxidants, which can damage tissues. The brain is particularly vulnerable to oxidative stress due to its lipid composition, high O2 consumption rate, and low levels of antioxidant enzymes. Moreover, hyperoxia can cause vasoconstriction and decreased O2 supply to the brain, posing a challenge to redox balance and neurodegenerative processes. Studies have shown that the severity of hyperoxia-induced brain damage varies with inspired O2 concentration and duration of exposure. Therefore, careful evaluation of the balance between benefits and risks of O2 supplementation, especially in clinical settings, is crucial.

Short-term hyperoxia induced mitochondrial respiratory chain complexes dysfunction and oxidative stress in lung of rats.

BACKGROUND: Oxygen therapy is an alternative for many patients with hypoxemia. However, this practice can be dangerous as oxygen is closely associated with the development of oxidative stress. METHODS: Male Wistar rats were exposed to hyperoxia with a 40% fraction of inspired oxygen (FIO2) and hyperoxia (FIO2 = 60%) for 120 min. Blood and lung tissue samples were collected for gas, oxidative stress, and inflammatory analyses. RESULTS: Hyperoxia (FIO2 = 60%) increased PaCO2 and PaO2, decreased blood pH and caused thrombocytopenia and lymphocytosis. In lung tissue, neutrophil infiltration, nitric oxide concentration, carbonyl protein formation and the activity of complexes I and II of the mitochondrial respiratory chain increased. FIO2 = 60% decreased SOD activity and caused several histologic changes. CONCLUSION: In conclusion, we have experimentally demonstrated that short-term exposure to high FIO2 can cause oxidative stress in the lung.

Infecção materna por SARS-CoV-2: descrição das notificações em gestantes / Maternal infection by SARS-CoV-2: description of notifications in pregnant women

Objetivo: Caracterizar as notificações de infecção por SARS-CoV-2 em gestantes em um município do sul de Santa Catarina. Métodos: Estudo transversal que avaliou as notificações de casos suspeitos de infecção por SARS-CoV-2 em gestantes no município de Tubarão, Santa Catarina, de março de 2020 a outubro de 2021. Coletaram-se os dados das fichas de notificação de infecção por SARS-CoV-2 da Fundação Municipal de Saúde e no Prontuário Eletrônico do Cidadão (PEC) das gestantes notificadas. A comparação da prevalência de confirmação segundo sintomas apresentados e características maternas foi realizada pela razão de prevalência (RP), com intervalo de confiança (IC) de 95%. Resultados: Foram registradas 555 notificações de gestantes suspeitas para a COVID-19, correspondentes a 487 mulheres. A prevalência de confirmação para a doença foi de 27,3%. O sintoma mais frequente no momento da notificação foi cefaleia (53,0%), entretanto o mais associado à confirmação foi a anosmia (RP: 2,28; IC 95%: 1,68-3,09). Das notificações registradas, 35,0% foram realizadas por gestantes que tiveram contato com casos suspeitos ou confirmados de COVID-19. O contato prévio foi mais relatado por gestantes assintomáticas, em comparação às gestantes que apresentaram sintomas (RP: 1,46; IC 95%: 1,12-1,91). Mulheres que relataram contato prévio com suspeitos ou confirmados para a COVID-19 apresentaram maior frequência de doença confirmada, quando comparadas às gestantes não expostas (RP: 1,80; IC 95%: 1,35-2,39). Conclusão: As gestantes, por terem maior susceptibilidade a surtos de doenças e gravidade do quadro, podem ter adotado com mais atenção medidas como a realização de testes diagnósticos quando em contato prévio com casos de COVID-19, mesmo assintomáticas.

Objective: To characterize the notifications of SARS-CoV-2 infection in pregnant women in a city in the South of Santa Catarina. Methods: Cross-sectional study that evaluated notifications of suspected cases of SARS-CoV-2 infection in pregnant women in the municipality of Tubarão, Santa Catarina, from March 2020 to October 2021. Data were collected from the SARS-CoV-2 infection notification forms from the Municipal Health Foundation, and from the Citizen's Electronic Health Record of the notified pregnant women. The comparison of the prevalence of confirmation according to symptoms and maternal characteristics was performed using the Prevalence Ratio (PR), with a confidence interval (CI) of 95%. Results: 555 notifications of suspected pregnant women for COVID-19 were registered, corresponding to 487 women. The prevalence of confirmation for the disease was 27.3%. The most frequent symptom at the time of notification was headache (53.0%), however, the most associated with confirmation was anosmia (PR: 2.28; 95% CI: 1.68-3.09). Of the notifications registered, 35.0% were made by pregnant women who had contact with suspected or confirmed cases of COVID-19. The previous contact was more frequently reported by asymptomatic pregnant women compared to pregnant women who had symptoms (PR: 1.46; 95% CI: 1.12-1.91). Women who reported previous contact with suspected or confirmed COVID-19 had a higher frequency of confirmed disease when compared to unexposed pregnant women (PR: 1.80; 95% CI: 1.35-2.39). Conclusion: Pregnant women, due to their greater susceptibility to disease outbreaks and disease severity, may have adopted more attentive measures such as diagnostic testing in the face of previous contact with cases of COVID-19, even if asymptomatic.

Hyperoxia by short-term promotes oxidative damage and mitochondrial dysfunction in rat brain.

Oxygen (O2) therapy is used as a therapeutic protocol to prevent or treat hypoxia. However, a high inspired fraction of O2 (FIO2) promotes hyperoxia, a harmful condition for the central nervous system (CNS). The present study evaluated parameters of oxidative stress and mitochondrial dysfunction in the brain of rats exposed to different FIO2. Male Wistar rats were exposed to hyperoxia (FIO2 40 % and 60 %) compared to the control group (FIO2 21 %) for 2 h. Oxidative stress, neutrophilic infiltration, and mitochondrial respiratory chain enzymes were determined in the hippocampus, striatum, cerebellum, cortex, and prefrontal cortex after O2 exposure. The animals exposed to hyperoxia showed increased lipid peroxidation, formation of carbonyl proteins, N/N concentration, and neutrophilic infiltration in some brain regions, like hippocampus, striatum, and cerebellum being the most affected. Furthermore, CAT activity and activity of mitochondrial enzyme complexes were also altered after exposure to hyperoxia. Rats exposed to hyperoxia showed increase in oxidative stress parameters and mitochondrial dysfunction in brain structures.

Socioeconomic and demographic profile of occupational morbidity and mortality in Brazil from 2009 to 2016.

INTRODUCTION: Occupational accidents occur as a result of work, and can lead to bodily harm or functional impairments that lead to death, or to the reduction or loss of working capacity. Occupational accidents are associated with two possible outcomes: morbidity or mortality. Morbidity refers to the subset of a population that develops an illness over a given period of time, while mortality refers to the number of individuals who die over a specified time period. OBJECTIVES: To assess occupational morbidity and mortality in Brazil in the period of 2009 to 2016. METHODS: An ecological study was conducted based on secondary data collected from incident records in the Social Security database. RESULTS: The outcomes of all occupational accidents reported in Brazil from 2009 to 2016 were extracted from the database. These data were then classified by geographical region and category in the National Classification of Economic Activities (Classificação Nacional de Atividades Econômicas), so as to calculate the prevalence of each outcome and the accident mortality rates, and compare these values across regions and occupational categories. CONCLUSIONS: The data show that the outcomes of occupational accidents are directly associated with socioeconomic sectors and the sociocultural characteristics of different regions in the country. These results make an important contribution to the characterization of occupational morbidity and mortality in Brazil.