Interferon-gamma signaling promotes cartilage regeneration after injury

Osteoarthritis is a common chronic disease and major cause of disability and chronic pain in ageing populations. In this pathology, the entire joint is involved, and the regeneration of articular cartilage still remains one of the main challenges. Here, we investigated the molecular mechanisms underlying cartilage regeneration in young mice using a full-thickness cartilage injury (FTCI) model. FTCI-induced cartilage defects were created in the femoral trochlea of young and adult C57BL/6 mice. To identify key molecules and pathways involved in the early response to cartilage injury, we performed RNA sequencing (RNA-seq) analysis of cartilage RNA at 3 days after injury. Young mice showed superior cartilage regeneration compared to adult mice after cartilage injury. RNA-seq analysis revealed significant upregulation of genes associated with the immune response, particularly in the IFN-γ signaling pathway and qRT-PCR analysis showed macrophage polarization in the early phase of cartilage regeneration (3 days) in young mice after injury, which might promote the removal of damaged or necrotic cells and initiate cartilage regeneration in response to injury. IFN-γR1- and IFN-γ-deficient mice exhibited impaired cartilage regeneration following cartilage injury. DMM-induced and spontaneous OA phenotypes were exacerbated in IFN-γR1-/- mice than in wild-type mice. Our data support the hypothesis that IFN-γ signaling is necessary for cartilage regeneration, as well as for the amelioration of post-traumatic and age-induced OA.

Correlation between the ratio of physician consultation fees to hourly minimum wage and consultation length: a cross-sectional study of nine countries

OBJECTIVES

Current healthcare reimbursement system is criticised for not adequately compensating physicians' cognitive services. This study was performed to examine primary care physicians' consultation fees in nine countries, relative to the national hourly minimum wage and to examine the correlations of the physician consultation fee with consultation length and other healthcare indices.

DESIGN AND OUTCOME MEASURES

Nine reference countries for which healthcare statistics are publicly available and outpatient consultation is compensated by fee-for-service payment were selected. A representative consultation fee was chosen to calculate the ratio of the consultation fee to the hourly minimum wage. The primary outcome was the correlation between the consultation fee/hourly minimum wage ratio and consultation length. In addition, the consultation fees were compared with fees for haemoglobin A1c tests and brain imaging. Pearson's method was primarily used for correlation analysis.

RESULTS

The mean representative consultation fee/hourly minimum wage ratio was 4.02 (median, 2.7; range, 0.80-10.36). The mean consultation length was 12.9 min (median, 14.7 min; range, 5-21.1 min). A significant correlation (r=0.79) was found between consultation length and the consultation fee/hourly minimum wage ratio. The ratio of consultation fee to hourly minimum wage was moderately negatively correlated with the annual number of physician visits, number of consultations per doctor and length of hospital stay. The brain CT fee/consultation fee ratio was moderately positively correlated with the number of CT units per 1 million population. In Japan and Korea, where the brain CT/consultation fee ratio was highest, the number of CT examinations per population was also highest.

CONCLUSIONS

The relationship of consultation fees to each country's hourly minimum wage varied in nine reference countries; however, it was strongly correlated with consultation length. The imbalance in compensation for cognitive services might drive increased use of imaging tests in some countries.