Locomotor activity rhythms in a significant proportion of Siberian hamsters (Phodopus sungorus sungorus) become arrhythmic after the light-dark (LD) cycle is phase-delayed by 5 h. Arrhythmia is apparent within a few days and persists indefinitely despite the presence of the photocycle. The failure of arrhythmic hamsters to regain rhythms while housed in the LD cycle, as well as the lack of any masking of activity, suggested that the circadian system of these animals had become insensitive to light. We tested this hypothesis by examining light-induced gene expression in the suprachiasmatic nucleus (SCN). Several weeks after the phase delay, arrhythmic and reentrained hamsters were housed in constant darkness (DD) for 24 h and administered a 30-min light pulse 2 h after predicted dark onset because light induces c-fos and per1 genes at this time in entrained animals. Brains were then removed, and tissue sections containing the SCN were processed for in situ hybridization and probed with c-fos and per1 mRNA probes made from Siberian hamster cDNA. Contrary to our prediction, light pulses induced robust expression of both c-fos and per1 in all reentrained and arrhythmic hamsters. A separate group of animals held in DD for 10 days after the light pulse remained arrhythmic. Thus, even though the SCN of these animals responded to light, neither the LD cycle nor DD restored rhythms, as it does in other species made arrhythmic by constant light (LL). These results suggest that different mechanisms underlie arrhythmicity induced by LL or by a phase delay of the LD cycle. Whereas LL induces arrhythmicity by desynchronizing SCN neurons, phase delay-induced arrhythmicity may be due to a loss of circadian rhythms at the level of individual SCN neurons.

Background: Clips are endoscopic mechanical devices with tensile and closure strength that can approximate tissue and provide hemostasis through a tamponade effect. Clips are ubiquitously used in endoscopic practice, and numerous studies have validated the clinical efficacy of clips, with recent guidelines recommending them as a first-line intervention for recurrent and persistent nonvariceal gastrointestinal bleeding. However, the safety profile for these devices has yet to be delineated, thus, we aim to investigate this feature by examining the adverse events reported to the Food and Drug Administration. Methods: Postmarketing surveillance data from the Food and Drug Administration Manufacturer And User Facility Device Experience database were analyzed from January 2012 to January 2021. The Manufacturer And User Facility Device Experience database is a reporting software and does not independently verify the details of complications. Results: Two thousand five hundred forty reports were issued, of which 287 were patient adverse events and 2766 were device problems. Activation, separation, and positioning issues were most common. No consequences or clinically significant impact on patients were seen in 1968 reports. Foreign bodies were seen in 97 cases, hemorrhage in 57 cases, tissue damage in 42 cases, embedded clips in tissues/plaques in 16 cases, perforation in 15 cases, lacerations in 6 cases, and infection in 3 cases. Conclusions: While the most commonly reported device problems involved activation, separation, and positioning, most patients were clinically unaffected. Moreover, perforation and infection were exceedingly rare, further highlighting the safety profile of endoscopic clips.

The clinical spectrum of Neisseria meningitidis can range from nasopharyngeal colonization to life-threatening invasive diseases such as meningitis. However, its etiologic role in invasive pyomyositis (PM) has never been reported before in the English language. In this study, we report the first case of PM in the English language and the second case in the literature caused by N meningitidis.

Circadian activity rhythms of most Siberian hamsters (Phodopus sungorus sungorus) fail to reentrain to a 5-h phase shift of the light-dark (LD) cycle. Instead, their rhythms free-run at periods close to 25 h despite the continued presence of the LD cycle. This lack of behavioral reentrainment necessarily means that molecular oscillators in the master circadian pacemaker, the SCN, were unable to reentrain as well. The authors tested the hypothesis that a phase shift of the LD cycle rendered the SCN incapable of responding to photic input. Animals were exposed to a 5-h phase delay of the photocycle, and activity rhythms were monitored until a lack of reentrainment was confirmed. Hamsters were then housed in constant darkness for 24 h and administered a 30-min light pulse 2 circadian hours after activity onset. Brains were then removed, and tissue sections containing the SCN were processed for in situ hybridization. Sections were probed with Siberian hamster c-fosand per1mRNA probes because light rapidly induces these 2 genes in the SCN during subjective night but not at other circadian phases. Light pulses induced robust expression of both genes in all animals that reentrained to theLDcycle, but no expression was observed in any animal that failed to reentrain. None of the animals exhibited an intermediate response. This finding is the first report of acute shift in a photocycle eliminating photosensitivity in the SCN and suggests that a specific pattern of light exposure may desensitize the SCN to subsequent photic input.