Identifying Patients with Osteoarthritis at Risk of Sarcopenia using the SARC-F.

BACKGROUND: Sarcopenia is an important modifiable risk factor in patients being considered for elective knee or hip replacement as it may be associated with a higher risk of post-operative joint replacement complications. Our objectives are to determine the prevalence of patients with osteoarthritis at risk of sarcopenia by using the SARC-F tool, and whether risk of sarcopenia is associated with referral to an orthopaedic surgeon. METHODS: We conducted a retrospective review of patients who were 60 years or older assessed at four Canadian musculoskeletal assessment centres. Patients completed the SARC-F as part of their assessment. Multivariable logistic regression analyses were conducted to determine association between risk of sarcopenia and the odds of referral to an orthopedic surgeon for surgical consultation. RESULTS: 3,697 patients were included and 67.8% (2,508/3,697) were at risk of sarcopenia. Prevalence was highest in those assessed for hip replacement at 72.3% (635/878). Patients at risk of sarcopenia were more likely to be referred to an orthopaedic surgeon (OR 1.299; SD 1.074-1.571). CONCLUSIONS: Patients with osteoarthritis assessed for joint replacement are at high risk of sarcopenia, particularly individuals undergoing potential hip replacement. Patients at risk of sarcopenia are more likely to be referred to orthopaedic surgery for surgical consultation.

Climate change and temperate zone insects: the tyranny of thermodynamics meets the world of limited resources.

Climate change will result in warmer temperatures and an increase in the frequency and severity of extreme weather events. Given that higher temperatures increase the reproductive rate of temperate zone insects, insect population growth rates are predicted to increase in the temperate zone in response to climate. This consensus, however, rests on the assumption that food is freely available. However, under conditions of limited food, the reproductive output of the Texan cricket Gryllus texensis (Cade and Otte) was highest at its current normal average temperature and declined with increasing temperature. Moreover, low food availability decreased survival during a simulated heat wave. Therefore, the effects of climate change on this species, and possibly on many others, are likely to hinge on food availability. Extrapolation from our data suggests that G. texensis will show larger yearly fluctuations in population size as climate change continues, and this will also have ecological repercussions. Only those temperate zone insects with a ready supply of food (e.g., agricultural pests) are likely to experience the predicted increase in population growth in response to climate change; food-limited species are likely to experience a population decline.

Some like it hot: the effects of climate change on reproduction, immune function and disease resistance in the cricket Gryllus texensis.

In many parts of the world, climate change is increasing the frequency and severity of heat waves. How do heat waves impact short-lived poikilotherms such as insects? In the cricket, Gryllus texensis, 6 days of elevated temperatures (i.e. 7°C above the average field temperature and 5°C above their preferred temperature) resulted in increased egg laying, faster egg development and greater mass gain. The increased temperature also increased activity of phenoloxidase and lysozyme-like enzymes, two immune-related enzymes, and enhanced resistance to the Gram-negative bacterium Serratia marcescens. When given a sublethal S. marcescens infection, G. texensis maintained increased reproductive output at the elevated temperature (33°C). These data suggest that heat waves could result in more numerous, disease resistant, crickets. However, resistance to the Gram-positive bacterium, Bacillus cereus was lower at temperatures above or below the average field temperature (26°C). A sublethal infection with B. cereus reduced egg laying at all temperatures and suppressed the increase in egg laying induced by higher temperatures. These results suggest that for some species-pathogen interactions, increased temperatures can induce trade-offs between reproduction and disease resistance. This result may partly explain why G. texensis prefers temperatures lower than those that produce maximal reproductive output and enhanced immune function.