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Vitamin A is essential for brain function, in addition to its important roles in vision, immunity, and reproduction. Previous studies have shown that retinoic acid (RA), the bioactive form of vitamin A, is involved in the regulation of various intracellular responses related to biological rhythms. RA is reported to affect the circadian rhythm by binding to RA receptors, such as receptors in the circadian feedback loops in the mammalian suprachiasmatic nucleus. However, evidence of the impacts of vitamin A deficiency (VAD) on biological rhythms is limited, and most of the related studies were conducted on animals. In this review, we described the physiological functions of biological rhythms and physiological pathways/molecular mechanisms regulating the biological rhythms. We then discussed the current understanding of the associations of VAD with biological rhythm disorders/diseases (sleep disorders, impairments in learning/memory, emotional disorders, and other immune or metabolism diseases) and summarized the currently proposed mechanisms (mainly by retinoid nuclear receptors and related proteins) for the associations. This review may help recognize the role of VAD in biological rhythm disorders and stimulate clinical or epidemiological studies to confirm the findings of related animal studies.

The track smoothness of high-speed railroads is severely limited to ensure train performance. The concrete continuous girder bridge is deformed to influence the smoothness of the bridge decks and track caused by creep bulge. There is a need to research the impact of beam creep on the dynamical response of bridge and train operation safety. This paper used Midas software to calculate the long-term deformation of large-span prestressed concrete continuous beam bridges under concrete creep and shrinkage. The train-bridge coupled system was established by adopting self-programming software. Thereafter, the large-term deformation results of the main girder are considered as track irregularity input into the vibration equation of the train-bridge system. The safety of the train operation was evaluated by calculating the dynamic response of the bridge and analyzing the criteria of train running safety. It was shown that the indicators of the large-span bridge are within the allowable code values under all working conditions. The bridge deformation under creep has an impact on the displacement and acceleration response of the bridge when a high-speed train passes through. There is no noticeable impact of creep deformation on the operational performance of trains. Nevertheless, the criteria for assessing the safety of trains’ operation, such as derailment factor, wheel load differences, lateral wheel forces, and vehicle acceleration, have been increased.