Neurosurgery and spinal adaptations in spaceflight: A literature review.

BACKGROUND: Spaceflight places astronauts in multiple environments capable of inducing pathological changes. Alterations in the spine have a significant impact on astronauts' health during and after spaceflight. Low back pain is an established and common intra-flight complaint. Intervertebral disc herniation occurs at higher rates in this population and poses significant morbidity. Morphological changes within intervertebral discs, vertebral bodies, and spinal postural muscles affect overall spine function and astronaut performance. There remains a paucity of research related to spaceflight-induced pathologies, and currently available reviews concern the central nervous system broadly while lacking emphasis on spinal function. OBJECTIVE: Our aim was to review and summarize available data regarding changes in spinal health with exposure to spaceflight, especially focusing on effects of microgravity. The authors also present promising diagnostic and treatment approaches wherein the neurosurgeon could positively impact astronauts' health and post-flight outcomes. MATERIALS AND METHODS: Articles included in this review were identified via search engine using MEDLINE, PubMed, Cochrane Review, Google Scholar, and references within other relevant articles. Search criteria included "spine and spaceflight", "vertebral column and spaceflight", "vertebral disc and spaceflight", and "muscle atrophy and spaceflight", with results limited to articles written in English from 1961 to 2020. References of selected articles were included as appropriate. RESULTS: Fifty-six articles were included in this review. Compositional changes at the intervertebral discs, vertebral bone, and paraspinal muscles contribute to undesirable effects on astronaut spinal function in space and contribute to post-flight pathologies. Risk of intervertebral disc herniation increases, especially during post-flight recovery. Vertebral bone degeneration in microgravity may increase risk for herniation and fracture. Paraspinal muscle atrophy contributes to low back pain, poorer spine health, and reduced stability. CONCLUSION: Anatomical changes in microgravity contribute to the development of spinal pathologies. Microgravity impacts sensory neurovestibular function, neuromuscular output, genetic expression, among other systems. Future developments in imaging and therapeutic interventions may better analyze these changes and offer targeted therapeutic interventions to decrease the burden of pain and other diseases of the spine in this population.

Characterization of 475 Novel, Putative Small RNAs (sRNAs) in Carbon-Starved Salmonella enterica Serovar Typhimurium.

An increasingly apparent role of noncoding RNA (ncRNAs) is to coordinate gene expression during environmental stress. A mounting body of evidence implicates small RNAs (sRNAs) as key drivers of Salmonella stress survival. Generally thought to be 50-500 nucleotides in length and to occur in intergenic regions, sRNAs typically regulate protein expression through base pairing with mRNA targets. In this work, through employing a refined definition of sRNAs allowing for shorter sequences and sRNA loci to overlap with annotated protein-coding gene loci, we have identified 475 previously unannotated sRNAs that are significantly differentially expressed during carbon starvation (C-starvation). Northern blotting and quantitative RT-PCRs confirm the expressions and identities of several of these novel sRNAs, and our computational analyses find the majority to be highly conserved and structurally related to known sRNAs. Importantly, we show that deletion of one of the sRNAs dynamically expressed during C-starvation, sRNA4130247, significantly impairs the Salmonella C-starvation response (CSR), confirming its involvement in the Salmonella CSR. In conclusion, the work presented here provides the first-ever characterization of intragenic sRNAs in Salmonella, experimentally confirms that sRNAs dynamically expressed during the CSR are directly involved in stress survival, and more than doubles the Salmonella enterica sRNAs described to date.