MUSCLE METABOLISM AFTER TOTAL KNEE ARTHROPLASTY WITH AND WITHOUT TOURNIQUET

Total knee arthroplasty (TKA) is the most common and cost effective surgery used to mitigate painful end-stage knee osteoarthritis. Projections suggest that by 2030 over 3.5 million older adults will undergo primary TKA annually in the U.S. It is estimated that a tourniquet is used by 95% of orthopedic surgeons during TKA to create a bloodless field and to ensure proper bone implant cementing. Prior studies by our lab suggest that tourniquet use may be detrimental, potentially leading to ischemia-reperfusion injury and cell swelling acutely following surgery; however, these studies focused on the vastus lateralis muscle. To our knowledge, less is known about how tourniquet use during TKA may impact the tibialis anterior (TA) muscle, which in older adults provides greater postural control support relative to younger individuals. PURPOSE: Determine if tourniquet use during TKA alters pH and oxidative capacity in the tibialis anterior (TA) 2 weeks after surgery. METHODS: Non-invasive in-vivo 31-phosphorous magnetic resonance spectroscopy was used to assess muscle metabolism in both the operative and non-operative TA 2 weeks ±4 days after surgery in two groups: those who had tourniquet (T) during surgery and those who did not (NT). RESULTS: Average resting pH in the NT group operative leg (n=2) was 7.025 and non-operative leg was 7.02. Average resting pH in the T group operative leg (n=3) was 7.01 and non-operative leg was 7.027. Oxidative capacity in the NT group operative leg (n=1) was .0177 and non-operative leg (n=1) was .0303. Oxidative capacity in the T group operative leg (n=2) was .0406 while the non-operative leg (n=1) was .0238. CONCLUSIONS: Our preliminary results suggest that tourniquet use during TKA alters muscle metabolism in the TA, which may be significant because older adults rely on the TA for balance control and ambulation more than younger individuals. Alterations in TA metabolism following TKA surgery using tourniquet may impact recovery of strength and function in this population of older adults. Further analysis is required in order to determine if TKA with tourniquet alters metabolism 2 weeks post-surgery. Supported by NIH grant: R01AG04640

Photochemistry of UV-Excited Trifluoroacetylacetone and Hexafluoroacetylacetone I: Infrared Spectra of Fluorinated Methylfuranones Formed by HF Photoelimination

The photochemistry of gas-phase 1,1,1-trifluoroacetylacetone (TFAA) excited with ultraviolet (UV) light involves a significant photoelimination channel that produces hydrogen fluoride and a fluorinated methylfuranone, 2,2-difluoro-5-methyl-3­(2<i>H</i>)-furanone (2FMF). This pathway is remarkable because it is a gas-phase unimolecular reaction that forms a five-membered ring product. This report is the first of such a TFAA photoelimination channel, which is similar to one observed with 1,1,1,5,5,5-hexafluoroacetylacetone (HFAA), resulting in 2,2-difluoro-5-trifluoromethyl-3­(2<i>H</i>)-furanone. We present infrared spectral observations of 2FMF produced by pulsed, UV-laser excitation of TFAA, along with analogous results from HFAA, supported by density functional theory (DFT) computational studies. DFT results for the infrared spectrum of 5-methyl-3­(2<i>H</i>)-furanone, the expected comparable acetylacetone photoelimination product, help suggest that UV excitation of acetylacetone fails to follow a similar type of photoelimination. We use a weighted RMS approach as a figure of merit for comparing calculated infrared frequencies with experimental data. Results from the three acetylacetones reveal how the presence of fluorine atoms in acetylacetone influences the gas-phase molecular photochemistry

MUSCLE CELL REGENERATIVE POTENTIAL FOLLOWING AMINO ACID SUPPLEMENTATION IN TOTAL KNEE ARTHROPLASTY PATIENTS

N. Bigot1, E. Owen2, T. Kirkpartick2, A. Poluso2, M. Bremer2, L. Strycker3, K. Smolkowski3, B. Lantz4, S. Shah4, C. Mohler4, B. Jewett4, J. Muyskens1, H. Dreyer1 1University of Oregon; 2Slocum Research and Education Foundation; 3Oregon Research Institute;4Slocum Center for Orthopedics and Sports Center, Eugene, OR PURPOSE: More than 600,000 Americans receive total knee arthroplasty (TKA) annually. Our goal is to improve functional outcomes following TKA by mitigating the extensive muscle loss that occurs during the first two weeks post surgery. Previously, we showed that essential amino acid supplementation (EAAs) improves function and reduces muscle atrophy as measured by MRI. This study aimed to determine muscle cell-level changes related to regenerative potential in TKA patients receiving EAAs compared to Placebo. METHODS Using a double-blind Placebo-controlled randomized clinical trial, 39 older adults (age 50-80 y) having TKA were randomized to ingest either 20 g of EAA (n = 19) or Placebo (n = 20) 2x/d between meals for 1 wk before, and 6 wk after TKA. Bilateral muscle biopsies (vastus lateralis (VL)) were obtained prior to surgery and at 1 or 2 weeks post TKA. Histological analysis determined cross-sectional area (CSA) of VL cells (anti-laminin), number of myonuclei per muscle cell (DAPI), fiber type composition (anti-MHC1), and satellite cell number (anti-Pax7). In addition, we assayed for shifts in inflammatory (M1) vs regenerative (M2) macrophage populations. RESULTS: Our preliminary results reveal satellite cell numbers are elevated in the EAA group vs Placebo for Type I cells (0.127±.02 vs, 0.073±.01, respectively, p=.054) and Type II cells (0.084±.02 vs. 0.039±.01, p=.64) after just 7 days of twice-daily EAA prior to surgery. After surgery in the EAA group, satellite cell numbers were reduced relative to baseline for both Type I (-37%) and II (-27%) fibers (p\u3c0.05). No changes in the satellite cell populations were measured in either leg for the Placebo group. Muscle CSA was reduced (-12%) in the Placebo group in the operative leg (p =.017). The treatment group did not display the corresponding decrease in CSA (p =.098). M1 macrophage populations were reduced in the operative leg of the treatment group at 1-week post surgery (p =.017). No changes in macrophage populations were measured for the Placebo group. CONCLUSIONS: Our data suggest that amino acid supplementation may attenuate muscle atrophy through preservation of satellite cells and a reduction in inflammatory macrophage numbers. NIA:R01AG04640

ATTENUATING MUSCLE ATROPHY USING ESSENTIAL AMINO ACID SUPPLEMENTATION BEFORE AND AFTER TOTAL KNEE ARTHROPLASTY

C. Policar1, L. Wheary1, M. Barnes1, J. Agtarap1, E. Owen2, T. Kirkpartick2, A. Poluso2, M. Bremer2, L. Strycker3, K. Smolkowski3, B. Lantz4, S. Shah4, C. Mohler4, B. Jewett4, J. Muyskens1, H. Dreyer1 1University of Oregon; 2Slocum Research and Education Foundation; 3Oregon Research Institute;4Slocum Center for Orthopedics and Sports Center, Eugene, OR PURPOSE: The demand for total knee arthroplasty (TKA) is projected to increase nearly seven-fold to 3.4 million surgeries performed annually in the U.S. by 2030. A proof-of-principle report by our group recently showed that essential amino acid (EAA) supplementation before and after TKA was successful in mitigating muscle atrophy after surgery vs.Placebo. The present investigation, conducted with a larger number of subjects having a wider age range (50-80 vs.60-80 y) and under the care of more surgeons, sought to repeat that study. METHODS: Using a double-blind placebo-controlled randomized clinical trial, 39 older adults (age 50-80 y) having TKA were randomized to ingest either 20 g of EAA (n = 19) or Placebo (n = 20) 2x/d between meals for 1 wk before, and 6 wk after TKA. At baseline, 2 wk post-TKA and 6 wk post-TKA, an MRI was obtained to determine mid-thigh muscle and adipose tissue volume; MRI scans were obtained at the Lewis Center for Neuroimaging. RESULTS: At 6 wk post-TKA, quadriceps muscle atrophy was significantly greater in the Placebo group in the operative leg quadriceps (-13.4%±1.9 [M±SE] change from baseline for Placebo vs.-8.5%±2.5 for EAA;p= .033) and in the non-operative leg quadriceps (-7.2%±1.4 change for Placebo vs.-1.5%±1.6 for EAA; p = .014). Similar results were found for the hamstrings, in the operative leg (-12.2%±1.4 change for Placebo vs.-7.4%±2.0 for EAA;p = .036) and in the non-operative leg (-7.5%±1.5 change for Placebo vs.-2.1%±1.3 for EAA;p = .005). Effect sizes (d) were .34, .68, .41, and .67 for operative quadriceps, non-operative quadriceps, operative hamstrings, and non-operative hamstrings, respectively. CONCLUSIONS: Twice-daily ingestion of 20 g of EAA for 7 d before and 42 d after (49 d total) TKA demonstrated muscle-sparing effects in the operative and non-operative quadriceps and hamstrings at 6 wk post-TKA. NIA:R01AG04640

Teaching the Spin Selection Rule: An Inductive Approach

In the group exercise described, students are guided through an inductive justification for the spin conservation selection rule (ΔS = 0). Although the exercise only explicitly involves various states of helium, the conclusion is one of the most widely applicable selection rules for the interaction of light with matter, applying, in various ways, to atoms and molecules of all sizes. Connections are made among several concepts routinely covered in physical chemistry courses including the Pauli Principle, orthonormal wave functions, overlap integrals, atomic term symbols, multiplicity, radiative lifetimes, fluorescence, and phosphorescence. Detailed student directions are included in the Supporting Information