Investigating the effects of chronic low-dose radiation exposure in the liver of a hypothermic zebrafish model

Sedative Agents, Synthetic Torpor, and Long-Haul Space Travel-A Systematic Review

BACKGROUND

With renewed interest in long-duration space missions, there is growing exploration into synthetic torpor as a countermeasure to mitigate physiological stressors. Sedative agents, particularly those used in clinical anesthesia, have been proposed to replicate aspects of natural torpor, including reduced metabolic rate, core temperature, and brain activity.

OBJECTIVES

This systematic review aims to evaluate the potential of sedative agents to induce torpor-like states suitable for extended spaceflight. The review specifically investigates their pharmacokinetics, pharmacodynamics, and performance under space-related stressors such as microgravity and ionizing radiation.

METHODS

We conducted a comprehensive search across multiple databases (e.g., PubMed, Scopus, Web of Science) for studies published from 1952 to 2024. Eligible studies included experimental, preclinical, and clinical investigations examining sedative agents (especially inhalation anesthetics) in the context of metabolic suppression or space-relevant conditions. Screening, selection, and data extraction followed PRISMA guidelines.

RESULTS

Out of the screened records, 141 studies met the inclusion criteria. These were thematically grouped into seven categories, including torpor physiology, anesthetic uptake, metabolism, and inhalation anesthetics. Sedative agents showed variable success in inducing torpor-like states, with inhalation anesthetics demonstrating promising metabolic effects. However, concerns remain regarding delivery methods, safety, rewarming, and the unknown effects of prolonged use in space environments.

CONCLUSIONS

Sedative agents, particularly volatile anesthetics, hold potential as tools for inducing synthetic torpor in space. Nevertheless, significant knowledge gaps and technical challenges persist. Further targeted research is required to optimize these agents for safe, controlled use in spaceflight settings.

DNAzyme hydrogels specifically inhibit the NLRP3 pathway to prevent radiation-induced skin injury in mice

Radiation-induced skin injury (RISI) is a frequent complication of radiotherapy, yet current preventive strategies exhibit suboptimal efficacy. Our previous publications have consistently demonstrated the effectiveness of biomaterials and hydrogels in preventing RISI. Based on comprehensive literature reviews, we speculate that NLRP3 overexpression plays a central role in the development of RISI. Therefore, designing DNAzyme (DZ)-hydrogels with targeted inhibition of NLRP3 overexpression is crucial for preventing RISI.To achieve this, we designed and screened the optimal NLRP3-DZ using bioinformatics, molecular dynamics, and gel electrophoresis methods. We encapsulated the NLRP3-DZ within ZIF-8 to enhance its stability, controlled release, and safety. To enhance the material's transdermal penetration and practicality, we attached the TAT transmembrane peptide. The final preparation and characterization of NLRP3-DZ@ZIF-8/TAT was achieved.In vitro cell models revealed that DZ-hydrogels exhibit high biosafety, effectively inhibit NLRP3 expression, promote cell migration, inhibit cell apoptosis, and possess antibacterial properties. Genomics analysis suggested that DZ-hydrogels may exert these functions by regulating changes in relevant mRNA pathways.Furthermore, we established a mouse model of RISI and found that the material can promote wound healing by regulating proteins associated with apoptosis, oxidative stress, and the inflammatory response. These research findings provide valuable insights for the prevention of RISI using DZ-hydrogels.

Transcriptome Profiling Reveals Enhanced Mitochondrial Activity as a Cold Adaptive Strategy to Hypothermia in Zebrafish Muscle

The utilisation of synthetic torpor for interplanetary travel once seemed farfetched. However, mounting evidence points to torpor-induced protective benefits from the main hazards of space travel, namely, exposure to radiation and microgravity. To determine the radio-protective effects of an induced torpor-like state we exploited the ectothermic nature of the Danio rerio (zebrafish) in reducing their body temperatures to replicate the hypothermic states seen during natural torpor. We also administered melatonin as a sedative to reduce physical activity. Zebrafish were then exposed to low-dose radiation (0.3 Gy) to simulate radiation exposure on long-term space missions. Transcriptomic analysis found that radiation exposure led to an upregulation of inflammatory and immune signatures and a differentiation and regeneration phenotype driven by STAT3 and MYOD1 transcription factors. In addition, DNA repair processes were downregulated in the muscle two days' post-irradiation. The effects of hypothermia led to an increase in mitochondrial translation including genes involved in oxidative phosphorylation and a downregulation of extracellular matrix and developmental genes. Upon radiation exposure, increases in endoplasmic reticulum stress genes were observed in a torpor+radiation group with downregulation of immune-related and ECM genes. Exposing hypothermic zebrafish to radiation also resulted in a downregulation of ECM and developmental genes however, immune/inflammatory related pathways were downregulated in contrast to that observed in the radiation only group. A cross-species comparison was performed with the muscle of hibernating Ursus arctos horribilis (brown bear) to define shared mechanisms of cold tolerance. Shared responses show an upregulation of protein translation and metabolism of amino acids, as well as a hypoxia response with the shared downregulation of glycolysis, ECM, and developmental genes.

Performance Evaluation of Radiation-Shielding Materials and Process Technology for Manufacturing Skin Protection Cream

Personnel using X-ray devices, the main source of radiation in medical institutions, are primarily affected by scattered rays. When interventionists use radiation for examinations/treatments, their hands may enter the radiation-generating area. The shielding gloves used for protection against these rays restrict movement and cause discomfort. Here, a shielding cream that directly adheres to the skin was developed and examined as a personal protective device; further, its shielding performance was verified. Bismuth oxide and barium sulfate were selected as shielding materials and comparatively evaluated in terms of thickness, concentration, and energy. With increasing wt% of the shielding material, the protective cream became thicker, resulting in improved protection. Furthermore, the shielding performance improved with increasing mixing temperature. Because the shielding cream is applied to the skin and has a protective effect, it must be stable on the skin and easy to remove. During manufacturing, the bubbles were removed, and the dispersion improved by 5% with increasing stirring speed. During mixing, the temperature increased as the shielding performance increased by 5% in the low-energy region. In terms of the shielding performance, bismuth oxide was superior to barium sulfate by approximately 10%. This study is expected to facilitate the mass production of cream in the future.

Genome-wide analyses of lung cancer after single high-dose radiation at five time points (2, 6, 12, 24, and 48 h)

Background: An increasing number of clinicians are experimenting with high-dose radiation. This study focuses on the genomic effects of high-dose single-shot radiotherapy and aims to provide a dynamic map for non-small cell lung cancer (NSCLC). Methods: We used whole-transcriptome sequencing to understand the evolution at molecular levels in A549 and H1299 exposed to 10 Gy X-rays at different times (2, 6, 12, 24, and 48 h) in comparison with the no radiation group. Ingenuity pathway analysis, ceRNA analysis, enrichment analysis, and cell cycle experiments are performed for molecular analyses and function analyses. Results: Whole-transcriptome sequencing of NSCLC showed a significant dynamic change after radiotherapy within 48 h. MiR-219-1-3p and miR-221-3p, miR-503-5p, hsa-miR-455-5p, hsa-miR-29-3p, and hsa-miR-339-5p were in the core of the ceRNA related to time change. GO and KEGG analyses of the top 30 mRNA included DNA repair, autophagy, apoptosis, and ferroptosis pathways. Regulation of the cell cycle-related transcription factor E2F1 might have a key role in the early stage of radiotherapy (2.6 h) and in the later stage of autophagy (24 and 48 h). Functions involving different genes/proteins over multiple periods implied a dose of 10 Gy was related to the kidney and liver pathway. Radiation-induced cell cycle arrest at the G2/M phase was evident at 24 h. We also observed the increased expression of CCNB1 at 24 h in PCR and WB experiments. Conclusion: Our transcriptomic and experimental analyses showed a dynamic change after radiation therapy in 48 h and highlighted the key molecules and pathways in NSCLC after high-dose single-shot radiotherapy.