Background: The World Health Organization has declared the end of the coronavirus disease 2019 (COVID-19) public health emergency. However, this did not indicate the end of COVID-19. Several months after the infection, numerous patients complain of respiratory or nonspecific symptoms; this condition is called long COVID. Even patients with mild COVID-19 can experience long COVID, thus the burden of long COVID remains considerable. Therefore, we conducted this study to comprehensively analyze the effects of long COVID using multi-faceted assessments. Materials and Methods: We conducted a prospective cohort study involving patients diagnosed with COVID-19 between February 2020 and September 2021 in six tertiary hospitals in Korea. Patients were followed up at 1, 3, 6, 12, 18, and 24 months after discharge. Long COVID was defined as the persistence of three or more COVID-19-related symptoms. The primary outcome of this study was the prevalence of long COVID after the period of COVID-19. Results: During the study period, 290 patients were enrolled. Among them, 54.5 and 34.6% experienced long COVID within 6 months and after more than 18 months, respectively. Several patients showed abnormal results when tested for post-traumatic stress disorder (17.4%) and anxiety (31.9%) after 18 months. In patients who underwent follow-up chest computed tomography 18 months after COVID-19, abnormal findings remained at 51.9%. Males (odds ratio [OR], 0.17; 95% confidence interval [CI], 0.05–0.53; P=0.004) and elderly (OR, 1.04; 95% CI, 1.00–1.09; P=0.04) showed a significant association with long COVID after 12–18 months in a multivariable logistic regression analysis. Conclusion Many patients still showed long COVID after 18 months post SARS-CoV-2 infection. When managing these patients, the assessment of multiple aspects is necessary.

γ-Radiation resistance is a major obstacle to the success of radiotherapy in colorectal cancer. Antioxidant-related factors contribute to resistance to radiation therapy and, therefore, are targets for improving the therapeutic response. In this study, we evaluated the molecular mechanisms underlying γ-radiation resistance using the colorectal cancer cell line SNUC5 and γ-radiation-resistant variant SNUC5/RR, including analyses of the role of nuclear factor erythroid 2-related factor 2 (NRF2), a transcription factor that regulates antioxidant enzymes, and related epigenetic regulators. Reactive oxygen species (ROS) levels, antioxidant enzyme expression, NRF2 expression, and nuclear translocation were higher in SNUC5/RR cells irradiated with or without 8 Gy than in SNUC5 cells. The DNA demethylase ten-eleven translocation 1 (TET1) expression and TET1 binding to the NRF2 promoter in SNUC5/RR cells were stronger than those in SNUC5 cells, indicating lower methylation of CpG islands in the NRF2 promoter.TET1 knockdown in SNUC5/RR cells suppressed NRF2 expression significantly. Additionally, histone mixed-lineage leukemia (MLL), a histone methyltransferase, was upregulated, leading to increased trimethylation of histone H3 lysine 4, whereas enhancer of zeste homolog 2 (EZH2), a histone methyltransferase, was downregulated, leading to decreased trimethylation of histone H3 lysine 27. Histone deacetylase (HDAC) and histone acetyltransferase (HAT) levels were lower and higher in SNUC5/RR cells than in SNUC5 cells, respectively. MLL and HAT knockdown in SNUC5/RR cells irradiated with or without 8 Gy decreased levels of NRF2 and heme-oxygenase 1, resulting in enhanced γ-radiation sensitivity. These findings support NRF2 as a target for improving the response to radiotherapy in patients with colorectal cancer.

γ-Radiation resistance is a major obstacle to the success of radiotherapy in colorectal cancer. Antioxidant-related factors contribute to resistance to radiation therapy and, therefore, are targets for improving the therapeutic response. In this study, we evaluated the molecular mechanisms underlying γ-radiation resistance using the colorectal cancer cell line SNUC5 and γ-radiation-resistant variant SNUC5/RR, including analyses of the role of nuclear factor erythroid 2-related factor 2 (NRF2), a transcription factor that regulates antioxidant enzymes, and related epigenetic regulators. Reactive oxygen species (ROS) levels, antioxidant enzyme expression, NRF2 expression, and nuclear translocation were higher in SNUC5/RR cells irradiated with or without 8 Gy than in SNUC5 cells. The DNA demethylase ten-eleven translocation 1 (TET1) expression and TET1 binding to the NRF2 promoter in SNUC5/RR cells were stronger than those in SNUC5 cells, indicating lower methylation of CpG islands in the NRF2 promoter.TET1 knockdown in SNUC5/RR cells suppressed NRF2 expression significantly. Additionally, histone mixed-lineage leukemia (MLL), a histone methyltransferase, was upregulated, leading to increased trimethylation of histone H3 lysine 4, whereas enhancer of zeste homolog 2 (EZH2), a histone methyltransferase, was downregulated, leading to decreased trimethylation of histone H3 lysine 27. Histone deacetylase (HDAC) and histone acetyltransferase (HAT) levels were lower and higher in SNUC5/RR cells than in SNUC5 cells, respectively. MLL and HAT knockdown in SNUC5/RR cells irradiated with or without 8 Gy decreased levels of NRF2 and heme-oxygenase 1, resulting in enhanced γ-radiation sensitivity. These findings support NRF2 as a target for improving the response to radiotherapy in patients with colorectal cancer.

Background: The World Health Organization has declared the end of the coronavirus disease 2019 (COVID-19) public health emergency. However, this did not indicate the end of COVID-19. Several months after the infection, numerous patients complain of respiratory or nonspecific symptoms; this condition is called long COVID. Even patients with mild COVID-19 can experience long COVID, thus the burden of long COVID remains considerable. Therefore, we conducted this study to comprehensively analyze the effects of long COVID using multi-faceted assessments. Materials and Methods: We conducted a prospective cohort study involving patients diagnosed with COVID-19 between February 2020 and September 2021 in six tertiary hospitals in Korea. Patients were followed up at 1, 3, 6, 12, 18, and 24 months after discharge. Long COVID was defined as the persistence of three or more COVID-19-related symptoms. The primary outcome of this study was the prevalence of long COVID after the period of COVID-19. Results: During the study period, 290 patients were enrolled. Among them, 54.5 and 34.6% experienced long COVID within 6 months and after more than 18 months, respectively. Several patients showed abnormal results when tested for post-traumatic stress disorder (17.4%) and anxiety (31.9%) after 18 months. In patients who underwent follow-up chest computed tomography 18 months after COVID-19, abnormal findings remained at 51.9%. Males (odds ratio [OR], 0.17; 95% confidence interval [CI], 0.05–0.53; P=0.004) and elderly (OR, 1.04; 95% CI, 1.00–1.09; P=0.04) showed a significant association with long COVID after 12–18 months in a multivariable logistic regression analysis. Conclusion Many patients still showed long COVID after 18 months post SARS-CoV-2 infection. When managing these patients, the assessment of multiple aspects is necessary.

γ-Radiation resistance is a major obstacle to the success of radiotherapy in colorectal cancer. Antioxidant-related factors contribute to resistance to radiation therapy and, therefore, are targets for improving the therapeutic response. In this study, we evaluated the molecular mechanisms underlying γ-radiation resistance using the colorectal cancer cell line SNUC5 and γ-radiation-resistant variant SNUC5/RR, including analyses of the role of nuclear factor erythroid 2-related factor 2 (NRF2), a transcription factor that regulates antioxidant enzymes, and related epigenetic regulators. Reactive oxygen species (ROS) levels, antioxidant enzyme expression, NRF2 expression, and nuclear translocation were higher in SNUC5/RR cells irradiated with or without 8 Gy than in SNUC5 cells. The DNA demethylase ten-eleven translocation 1 (TET1) expression and TET1 binding to the NRF2 promoter in SNUC5/RR cells were stronger than those in SNUC5 cells, indicating lower methylation of CpG islands in the NRF2 promoter.TET1 knockdown in SNUC5/RR cells suppressed NRF2 expression significantly. Additionally, histone mixed-lineage leukemia (MLL), a histone methyltransferase, was upregulated, leading to increased trimethylation of histone H3 lysine 4, whereas enhancer of zeste homolog 2 (EZH2), a histone methyltransferase, was downregulated, leading to decreased trimethylation of histone H3 lysine 27. Histone deacetylase (HDAC) and histone acetyltransferase (HAT) levels were lower and higher in SNUC5/RR cells than in SNUC5 cells, respectively. MLL and HAT knockdown in SNUC5/RR cells irradiated with or without 8 Gy decreased levels of NRF2 and heme-oxygenase 1, resulting in enhanced γ-radiation sensitivity. These findings support NRF2 as a target for improving the response to radiotherapy in patients with colorectal cancer.

Background: The World Health Organization has declared the end of the coronavirus disease 2019 (COVID-19) public health emergency. However, this did not indicate the end of COVID-19. Several months after the infection, numerous patients complain of respiratory or nonspecific symptoms; this condition is called long COVID. Even patients with mild COVID-19 can experience long COVID, thus the burden of long COVID remains considerable. Therefore, we conducted this study to comprehensively analyze the effects of long COVID using multi-faceted assessments. Materials and Methods: We conducted a prospective cohort study involving patients diagnosed with COVID-19 between February 2020 and September 2021 in six tertiary hospitals in Korea. Patients were followed up at 1, 3, 6, 12, 18, and 24 months after discharge. Long COVID was defined as the persistence of three or more COVID-19-related symptoms. The primary outcome of this study was the prevalence of long COVID after the period of COVID-19. Results: During the study period, 290 patients were enrolled. Among them, 54.5 and 34.6% experienced long COVID within 6 months and after more than 18 months, respectively. Several patients showed abnormal results when tested for post-traumatic stress disorder (17.4%) and anxiety (31.9%) after 18 months. In patients who underwent follow-up chest computed tomography 18 months after COVID-19, abnormal findings remained at 51.9%. Males (odds ratio [OR], 0.17; 95% confidence interval [CI], 0.05–0.53; P=0.004) and elderly (OR, 1.04; 95% CI, 1.00–1.09; P=0.04) showed a significant association with long COVID after 12–18 months in a multivariable logistic regression analysis. Conclusion Many patients still showed long COVID after 18 months post SARS-CoV-2 infection. When managing these patients, the assessment of multiple aspects is necessary.