A Molecular Link between the Circadian Clock, DNA Damage Responses, and Oncogene Activation

Circadian clocks enhance the efficiency and survival of living things by organizing their behavior and body functions. There has been a long history of research seeking a link between circadian clock and tumorigenesis. Studies of animal models and human tumor samples have revealed that the dysregulation of circadian clocks is an important endogenous factor causing mammalian cancer development. The core circadian clock regulators have been implicated in the control of both the cell cycle and DNA damage responses (DDR). Conversely, several intracellular signaling cascades that play important roles in regulation of the cell cycle and the DDR also contribute to circadian clock regulation. This review describes selected regulatory aspects of circadian clocks, providing evidence of a molecular link of the circadian clocks with cellular DDR

Light-Dependent Regulation of Circadian Clocks in Vertebrates

Circadian clocks are intrinsic time-tracking systems that endow organisms with a survival advantage. The core of the circadian clock mechanism is a cell-autonomous and self-sustained oscillator called a cellular clock, which operates via a transcription-/translation-based negative feedback loop. Under natural conditions, circadian clocks are entrained to a 24-hour day by environmental time cues, most commonly light. In mammals, circadian clocks are regulated by cellular clocks located in the central nervous system, such as the suprachiasmatic nucleus (SCN), and in other peripheral tissues. Importantly, mammals have no photoreceptors in the peripheral tissues; therefore the effect of light on peripheral clocks is indirect. By striking contrast, zebrafish peripheral cellular clocks are directly light responsive. This characteristic of the zebrafish cellular clock has contributed to the identification of molecules and signaling pathways that are involved in the light-dependent regulation of the cellular clock. Here, selected light-dependent regulatory mechanisms of circadian clocks in mammals and zebrafish are described

How do case presentation teaching methods affect learning outcomes?-SNAPPS and the One-Minute preceptor

Background: Various techniques have been developed to enable preceptors to teach residents effectively in outpatient settings to promote active learning, including SNAPPS and the One-Minute Preceptor (OMP). This study aimed to ascertain the differences between SNAPPS and the OMP in case presentation content and learner evaluation when used to teach residents about case presentation. Methods: From 2011 to 2013, participants were 71 junior clinical residents employed in two hospitals for clinical training. They were randomly allocated to two groups, one using SNAPPS and the other the OMP. From recorded discussions, the "differential diagnoses", "questions and uncertainties", "treatment plans", and "learning issues" were counted. Also, a self-evaluation form was distributed at the end of the study to evaluate the residents' satisfaction with the case presentation. Results: Members of the SNAPPS group used significantly more meaning units related to questions and uncertainties compared with those of the OMP group (P < 0.001). Self-evaluation sheets revealed that members of the SNAPPS group had significantly higher positive responses than those of the OMP group in terms of the following evaluations: "It was easy to bring up questions and uncertainties" (P = 0.046), "It was easy to present the case efficiently" (P = 0.002), "It was easy to present the case in the sequence given" (P = 0.029), and "I was able to give an in-depth case presentation" (P = 0.005). Conclusions: SNAPPS may induce more meaning units related to questions and uncertainties and give more satisfaction to residents than the OMP

Distinct responsiveness to rifaximin in patients with hepatic encephalopathy depends on functional gut microbial species

Abstract Hepatic encephalopathy (HE) is the neuropsychiatric complication of liver cirrhosis (LC). The influence of gut microbiota on HE pathogenesis has been suggested but not precisely elucidated. Here, we investigate how the gut microbial profile changed in patients with HE to clarify the functional gut microbial species associated with HE. We focused on their responses to rifaximin (RFX), a nonabsorbable antibiotic used in HE therapy. Feces samples were collected from patients with decompensated LC (all HE), patients with compensated LC, and healthy controls, and fecal gut microbial profiles were compared using 16S ribosomal RNA gene amplicon and metagenomic sequencing. The linear discriminant analysis effect size was used to identify specific species. Urease‐positive Streptococcus salivarius, which can produce ammonia, was identified as the most significantly abundant gut microbiota in the HE group, and its ability to elevate the levels of blood ammonia as well as brain glutamine was experimentally verified in mice. Urease‐negative Ruminococcus gnavus was also identified as a significantly abundant species in patients with RFX‐nonresponsive HE after RFX administration. Interestingly, R. gnavus enhanced urease activity of recombinant urease itself, implying that R. gnavus could amplify ammonia production of surrounding urease‐positive microbiota. Furthermore, the sensitivity of S. salivarius and R. gnavus to RFX depended on conjugated secondary bile acid levels, suggesting a therapeutic potential of the combined use of secondary bile acid levels with RFX for enhancing the efficacy of RFX. This study identified specific gut bacterial species abundant in patients with HE and verified their functions linked to HE pathophysiology. Targeting these bacteria could be a potentially effective strategy to treat HE