No evidence of delay in colorectal cancer diagnosis during the COVID-19 pandemic in Gwangju and Jeonnam, Korea

Objectives: We evaluated whether the coronavirus disease 2019 (COVID-19) pandemic caused delays in the diagnosis and treatment of colorectal cancer (CRC) in Korea, where there have been no regional or hospital lockdowns during the pandemic period. Methods: Data on CRC patients (n=1,445) diagnosed in Gwangju Metropolitan City and Jeonnam Province between January 2019 and December 2021 were assessed. The stage at the time of CRC diagnosis, route to diagnosis, time to initial cancer treatment, and length of hospital admission were compared before and during the COVID-19 pandemic. Logistic regression was also performed to identify factors associated with the risk for diagnosis in an advanced stage. Results: No negative effects indicating a higher CRC stage at diagnosis or delayed treatment during the pandemic were observed. Instead, the risk for an advanced stage at diagnosis (TNM stage III/IV) decreased in CRC patients diagnosed during the pandemic (odds ratio, 0.768; 95% confidence interval, 0.647 to 0.911). No significant differences in the interval from diagnosis to operation or chemotherapy were observed. Conclusion: No negative effects on CRC diagnosis and treatment were found until the end of 2021, which may be related to the small magnitude of the COVID-19 epidemic, the absence of a lockdown policy in Korea, and the rebound in the number of diagnostic colonoscopy procedures in 2021.

Additive manufacturing of the core template for the fabrication of an artificial blood vessel: the relationship between the extruded deposition diameter and the filament/nozzle transition ratio.

An artificial blood vessel with a tubular structure was additively manufactured via fused deposition modeling (FDM) starting from a single strand of polyvinyl alcohol (PVA) filament coated with a specific thickness of biocompatible polydimethylsiloxane (PDMS), followed by removal of the inner core via hydrogen peroxide leaching under sonication. In particular, we examined the relationship between the extruded deposition diameter and the filament migration speed/nozzle control speed (referred to as the filament/nozzle transition ratio), which is almost independent of the extruded deposition flow rate due to the weak die-swelling and memory effects of the extruded PVA arising from its intrinsically low viscoelasticity. The chemical stability of the PDMS during sonication in the hydrogen peroxide solution was then determined by spectroscopic techniques. The PDMS displayed no mechanical degradation in the hydrogen peroxide solution, resulting in similar fracture elongation and yield strength to those of the pristine specimen without the leaching treatment. As a further advantage, the inside surface of the PDMS was smooth regardless of the hydrogen peroxide leaching under sonication. The potential application of the as-developed scaffold in soft tissue engineering (particularly that involving vascular tissue regeneration) was demonstrated by the successful transplantation of the artificial blood vessel in a right-hand surgical replica used in a clinical simulation.