The influence of different cellulose ethers on both the handling and mechanical properties of calcium phosphate cements for bone substitution

The influence of cellulose ether additives (CEAs) on the performance of final calcium phosphate cement (CPC) products is thoroughly investigated. Four CEAs were added into the liquid phase of apatitic CPCs based on the hydrolysis of α-tricalcium phosphate, to investigate the influence of both molecular weight and degree of substitution on the CPCs’ properties, including handling (e.g. injectability, cohesion, washout resistance and setting time), microstructure (e.g. porosity and micromorphology) and mechanical properties (e.g. fracture toughness and compressive strength). The results showed that even a small amount of CEAs modified most of these CPCs’ features, depending on the structural parameters of the CEAs. The CEAs dramatically improved the injectability, cohesion and washout resistance of the pastes, prolonged the final setting time and increased the porosity of CPCs. Moreover, the CEAs had an evident toughening effect on CPCs, and this effect become more significant with increasing molecular weight and mass fraction of CEAs, inducing a significant tolerance to damage. Overall, the molecular weight of CEAs played a major role compared to their degree of substitution in CPCs’ performances.     

Prevalence of Thoracic Aortic Aneurysms in Patients with Degenerative Abdominal Aortic Aneurysms: Results from the Prospective ACTA Study

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Senescence in natural populations of animals: Widespread evidence and its implications for bio-gerontology

That senescence is rarely, if ever, observed in natural populations is an oft-quoted fallacy within bio-gerontology. We identify the roots of this fallacy in the otherwise seminal works of Medawar and Comfort, and explain that under antagonistic pleiotropy or disposable soma explanations for the evolution of senescence there is no reason why senescence cannot evolve to be manifest within the life expectancies of wild organisms. The recent emergence of long-term field studies presents irrefutable evidence that senescence is commonly detected in nature. We found such evidence in 175 different animal species from 340 separate studies. Although the bulk of this evidence comes from birds and mammals, we also found evidence for senescence in other vertebrates and insects. We describe how high-quality longitudinal field data allow us to test evolutionary explanations for differences in senescence between the sexes and among traits and individuals. Recent studies indicate that genes, prior environment and investment in growth and reproduction influence aging rates in the wild. We argue that – with the fallacy that wild animals do not senesce finally dead and buried – collaborations between bio-gerontologists and field biologists can begin to test the ecological generality of purportedly ‘public’ mechanisms regulating aging in laboratory models.     

Retrospective analysis of physical therapy utilization by the specificity of the diagnosis and order written on the referral

Background: Arguments against reimbursement for direct access to physical therapy (PT) are that a physician examination is necessary to diagnose and that there is a potential for increased cost. Objective: To determine what percentage of PT referrals had a specific diagnosis and treatment orders. Additionally, specific and non-specific diagnoses and treatment orders were compared in regards to PT units billed, average visits per referral, and average cost per referral. Methods: The charts of 1,000 patients treated in outpatient PT underwent a retrospective chart review. Interferential statistics were used to determine if there was a statistically significant difference between specific and non-specific diagnoses and treatment orders in regard to PT units billed, average visits per referral, and average cost per referral. Results: Twenty-nine percent of all referring diagnoses were non-specific in nature and 58% contained treatment orders that were non-specific. Charts with a specific diagnosis had a statistically significant higher utilization as compared to non-specific diagnoses (p ≤ 0.001). Patients with a specific treatment order also displayed a statistically significant larger average in billed units, average visits per referral, and average reimbursement per referral than those without a specific treatment order (p ≤ 0.0001). Conclusion: Our findings suggest that a physician diagnosis and referral may not be required to direct care for patients seeking PT services. Third-party payers that require a physician referral for PT services may be delaying access to healthcare and increasing costs.