Chemical applicability domain of the Local Lymph Node Assay (LLNA) for skin sensitisation potency. Part 2. The biological variability of the murine Local Lymph Node Assay (LLNA) for skin sensitisation

The Local Lymph Node Assay (LLNA) is the most common in vivo regulatory toxicology test for skin sensitisation, quantifying potency as the EC3, the concentration of chemical giving a threefold increase in thymidine uptake in the local lymph node. Existing LLNA data can, along with clinical data, provide useful comparator information on the potency of sensitisers. Understanding of the biological variability of data from LLNA studies is important for those developing non-animal based risk assessment approaches for skin allergy. Here an existing set of 94 EC3 values for 12 chemicals, all tested at least three times in the same vehicle have been analysed by calculating standard deviations (SD) for logEC3 values. The SDs range from 0.08 to 0.22. The overall SD for the 94 logEC3 values is 0.147. Thus the 95% confidence limits (2xSD) for LLNA EC3 values are within a factor of 2, comparable to those for physico-chemical measurements such as partition coefficients and solubility. The residual SDs of Quantitative Mechanistic Models (QMMs) based on physical organic chemistry parameters are similar to the overall SD of the LLNA, indicating that QMMs of this type are unlikely to be bettered for predictive accuracy.     

Exercise rapidly increases eukaryotic elongation factor 2 phosphorylation in skeletal muscle of men

Protein synthesis in skeletal muscle is known to decrease during contractions but the underlying regulatory mechanisms are unknown. Here, the effect of exercise on skeletal muscle eukaryotic elongation factor 2 (eEF2) phosphorylation, a key component in protein translation machinery, was examined. Eight healthy men exercised on a cycle ergometer at a workload eliciting ∼67% peak pulmonary oxygen consumption     with skeletal muscle biopsies taken from the vastus lateralis muscle at rest as well as after 1, 10, 30, 60 and 90 min of exercise. In response to exercise, there was a rapid (i.e. < 1 min) 5- to 7-fold increase in eEF2 phosphorylation at Thr56 that was sustained for 90 min of continuous exercise. The in vitro activity of skeletal muscle eEF2 kinase was not altered by exercise indicating that the increased activity of eEF2 kinase to eEF2 is not mediated by covalent mechanisms. In support of this, the increase in AMPK activity was temporally unrelated to eEF2 phosphorylation. However, skeletal muscle eEF2 kinase was potently activated by Ca²⁺–calmodulin in vitro , suggesting that the higher eEF2 phosphorylation in working skeletal muscle is mediated by allosteric activation of eEF2 kinase by Ca²⁺ signalling via calmodulin. Given that eEF2 phosphorylation inhibits eEF2 activity and mRNA translation, these findings suggest that the inhibition of protein synthesis in contracting skeletal muscle is due to the Ca²⁺-induced stimulation of eEF2 kinase.     

Use of Post-Acute Care by Medicare Beneficiaries With a Diagnosis of Dementia

ObjectivesHospitalized patients with dementia transitioning to post-acute care may be particularly vulnerable to changes in post-acute care utilization driven by payment reforms; however, use of post-acute care in this population is incompletely understood. We sought to describe post-acute care utilization in skilled nursing facilities (SNFs) and from home health (HH) agencies among Medicare beneficiaries with a diagnosis of dementia.DesignRetrospective, observational study using 100% sample of Medicare beneficiaries from 2013 to 2016.Setting and ParticipantsWe identified hospitalizations and diagnoses using Medicare Provider Analysis and Review (MedPAR), SNF stays using the Minimum Data Set, HH episodes using the Outcome and Assessment Information Set, and dementia diagnoses using the Medicare Beneficiary Summary File Chronic Conditions segment.MethodsWe calculated overall utilization and trends in post-acute care use over time, stratified by dementia diagnosis, type of post-acute care (SNF vs HH), and payer (fee-for-service vs Medicare Advantage).ResultsOf the 9,762,208 Medicare fee-for-service beneficiaries who received post-acute care from 2013 to 2016, 3,155,560 (32.3%) carried a diagnosis of dementia. Rates of post-acute care use were similar over time. More beneficiaries with a diagnosis of dementia received post-acute care (44.2% vs 27.7%) and proportionally more SNF care (71.7% vs 49.6%). Overall use and trends were similar in the Medicare Advantage population.Conclusions and ImplicationsOne-third of all fee-for-service Medicare beneficiaries receiving post-acute care have a diagnosis of dementia, and more than 7 in 10 receive this care in an SNF. These findings serve as a foundation for needed evaluations of how best to meet the post-hospital needs of older adults with dementia.     

Impact of Tibial Tubercle Osteotomy on Final Outcome in Revision Total Knee Arthroplasty: Our Experience and Technique in Pakistan

BackgroudDue to extensive fibrosis during revision surgery, adequate exposure is essential and it can be achieved with several extensile approach options, such as tibial tubercle osteotomy. Information regarding surgical exposure during revision arthroplasty is limited in developing countries, such as Pakistan, due to the lack of adequate data collection and follow-up. Therefore, the purpose of this study was to evaluate the impact of tibial tubercle osteotomy on final outcome of revision total knee arthroplasty (TKA).MethodsA total of 231 revision TKAs were performed between January 2008 and December 2017. Twenty-nine patients underwent tibial tubercle osteotomy for adequate exposure during revision surgery. Of these, 27 patients with complete follow-up were included in our study. Factors examined include age at the time of revision surgery, gender, comorbidities, arthroplasty site (right or left), body mass index (BMI), and primary indications for the tibial tubercle osteotomy during revision TKA. Functional outcome was measured by using Knee Society score (KSS) at 3 months and the final follow-up. All statistical analysis was done using SPSS version 20.0 with a p-value < 0.05 considered significant.ResultsOut of 27 patients, 6 patients (22.2%) were men and 21 patients (77.7%) were women. Right knee revision arthroplasty was performed in 15 patients (55.5%), left knee revision arthroplasty was performed in 12 patients (44.4%), and bilateral revision surgery was performed in only 1 patient (3.7%). The mean BMI was 29.2 kg/m². We used a constrained condylar knee in 20 patients (74%), a rotating hinge knee in 5 patients (18.5%), and mobile bearing tray plus metaphyseal sleeves in 2 patients (7.4%). The KSS was 52.21 ± 4.05 preoperatively, and 79.42 ± 2.2 and 80.12 ± 1.33 at 3 months and 12 months, respectively. Radiological union was achieved in all patients at 3 months. Of 27 patients, only 1 patient (3.7%) had proximal migration of the osteotomy site at 6 months: the patient was asymptomatic and union was also achieved and, therefore, no surgical intervention was performed.ConclusionsTibial tubercle osteotomy during revision TKA can be a safe and reliable technique with superior outcomes and minimal complication rates.