Hip implants with a delta ceramic or oxidised zirconium head and highly crosslinked polyethylene liner or cup had the lowest risk of revision during the 15 years after surgery, a new study led by the University of Bristol has found.  The research could help hospitals, surgeons and patients to choose what hip implant to use for replacement surgery.

Although travel restrictions and social measures during the COVID-19 pandemic led to a dramatic global drop in seasonal influenza cases, certain influenza lineages in specific regions kept the virus circulating and evolving, according to a new study. This was true in tropical areas with fewer travel restrictions, for example, including South and West Asia. The spread of seasonal influenza is closely tied to social behavior, particularly air travel, and to the periodic evolution of new virus strains that evade immunity from prior infections or vaccinations. In 2020, nonpharmaceutical interventions (NPIs) introduced to combat COVID-19 – such as lockdown policies, mandated social distancing, masking, and travel bans – dramatically impacted influenza virus transmission and evolution. Due to these interventions, cases of seasonal influenza caused by A subtypes H1N1 and H3N2, as well as influenza B subtypes Victoria and Yamagata, declined sharply across the globe.

Here, Zhiyuan Chen and colleagues investigated how these changes affected the spread, distribution, and evolutionary dynamics of seasonal influenza lineages. Using a phylodynamic approach, Chen et al. combined epidemiological, genetic, and international travel data from before, during, and after the COVID-19 pandemic and found that the onset of the pandemic led to a shift in the intensity and structure of international influenza transmission. Although influenza cases significantly dropped globally during the pandemic’s peak, in South Asia and West Asia, regions that had relatively fewer pandemic restrictions, the circulation of influenza A and influenza B/Victoria lineages, respectively, continued. That circulation served as important evolutionary sources, or “phylogenetic trunk locations,” of influenza viruses during the pandemic period. By March 2023, as global air traffic resumed, the circulation of influenza lineages returned to pre-pandemic levels, highlighting the virus’ resilience to long-term disruption and its reliance on global air travel patterns to spread. Notably, however, the findings also show that the influenza B/Yamagata lineage appears to have disappeared since the start of the pandemic, suggesting that the lineage may have since gone extinct. “The study by Chen et al. further reinforces that nonpharmaceutical interventions can be incredibly effective in disrupting viral transmission, pathogen diversity, and antigenic evolution, and are arguably more effective than vaccine efforts alone,” write Pejman Rohani and Justin Bahl in a related Perspective.

Disruptions between the brain’s master circadian clock and the liver’s internal clock, communicated via the hepatic afferent vagal nerve (HVAN), can lead to unhealthy eating patterns and increased weight gain, according to a new study in mice. The findings identify the neural link as a potential therapeutic target for obesity and metabolic dysfunction related to circadian disruption. In mammals, circadian rhythms are controlled by the suprachiasmatic nucleus (SCN) – a small part of the brain’s hypothalamus that regulates the body’s circadian rhythms. This cycle triggers a feedback loop involving key clock genes that keep time in the body. Although the SCN manages overall timing, nearly all cells in the body – including those in the liver – have their own internal clocks. While the brain’s master clock in the SCN is set by light cues, resulting in a ~24-hour cycle, the liver’s molecular clock is especially responsive to eating patterns. Synchronizing the light-based SCN clock with the liver’s food-based clock is crucial for balanced metabolism. When these clocks fall out of sync, through shiftwork or jetlag experienced by humans, for example, it can lead to serious health issues, including a higher risk of cardiometabolic disease and type 2 diabetes. Although these consequences are well known, the mechanisms through which circadian desynchronization between the liver and brain occurs are poorly understood.

To explore the relationship between liver circadian rhythms and feeding behavior, Lauren Woodie and colleagues deleted the core clock components REV-ERB⍺ and REV-ERBβ in mouse liver cells. The authors found that mice with liver clock gene deletions exhibited disrupted feeding rhythms, consuming more calories during their resting phase and throughout the 24-hour cycle. This confirms that rhythmic activity in this feeding center requires a rhythmic liver. However, when the hepatic vagal afferent nerve (HVAN) – which creates a channel of two-way communication between the brain and the liver – was severed, the overeating behavior in these mice caused by gene deletion in the liver was alleviated. “The implication of the findings of Woodie et al. is that the circadian-disrupted liver sends signals to the arcuate nucleus to drive disordered eating and that this circuit explains the obesity seen in response to prevalent human circadian and sleep disruption,” write Noelia Martinez-Sanchez and David Ray in a related Perspective. “Identification of this pathway opens the opportunity to reverse the human epidemic of obesity.”