Supporting Rehabilitation of Rural Patients Receiving Total Knee Arthroplasty Through Physical Activity: Perceptions of Stakeholder Groups.

OBJECTIVE: To identify how patients with osteoarthritis waiting for and recovering from total knee arthroplasty (TKA) conceptualized and participated in physical activity behaviors in their rural setting and to gather perceptions of health care professionals and rehabilitation decision-makers on the feasibility of a remotely led physical activity coaching intervention. METHODS: Using a qualitative descriptive study, we collected data from three stakeholder groups: patients waiting for or recovering from TKA (interviews), health professionals delivering a physical activity intervention to patients in the recovering cohort (focus group), and rehabilitation leaders involved in decision-making at the local or provincial level (interviews). RESULTS: A total of 38 individuals provided their perspectives (25 patients, five health professionals, eight decision-makers). Patients waiting for and recovering from surgery described the attributes of their rural environment that supported and restricted their ability to participate in physical activities. Patients recovering from TKA appreciated support for goal-setting and problem-solving during their rehabilitation. Health care professionals and decision-makers commented on the benefits of the program's innovative use of relatively simple technology to support remotely delivered, personalized rehabilitation in rural settings. CONCLUSION: This study adds to the limited voice of and about patients living with osteoarthritis who reside in rural settings and identifies facilitators and barriers to TKA rehabilitation in this population. Our findings highlight that it is important to consider the local context and the resources available to patients as they navigate living well with osteoarthritis.

Characterization of an archaeal inorganic pyrophosphatase from Sulfolobus islandicus using a [31P]-NMR-based assay.

Inorganic pyrophosphatase catalyzes the conversion of pyrophosphate to phosphate and is often critical for driving reactions forward in cellular processes such as nucleic acid and protein synthesis. Commonly used methods for quantifying pyrophosphatase enzyme activity employ reacting liberated phosphate with a second molecule to produce absorbance changes or employing a second enzyme in coupled reactions to produce a product with a detectable absorbance. In this investigation, a novel [31P]-NMR spectroscopy-based assay was used to quantitatively measure the formation of phosphate and evaluate the activity of inorganic pyrophosphatase from the thermoacidophilic Crenarchaeota Sulfolobus islandicus. The enzymatic activity was directly measured via integration of the [31P] resonance associated with the phosphate product (δ = 2.1 ppm). Sulfolobus islandicus inorganic pyrophosphatase preferentially utilized Mg2+ as divalent cation and had pH and temperature optimums of 6.0 of 50 °C, respectively. The Vmax value was 850 µmol/min/mg and the Km for pyrophosphate was 1.02 mM. Sequence analysis indicates the enzyme is a Family I pyrophosphatase. Sulfolobus islandicus inorganic pyrophosphatase was shown to be inhibited by sodium fluoride with a IC50 of 2.26 mM, compared to a IC50 of 0.066 mM for yeast inorganic pyrophosphatase. These studies reveal that a [31P]-NMR spectroscopy-based assay is an effective method for analyzing catalysis by phosphate-producing enzymes.

Development of a new and reliable assay for choline kinase using 31P NMR.

Choline kinase catalyzes the conversion of choline to phosphocholine (PC) by transferring a phosphate group from adenosine triphosphate (ATP) as the first step in the biosynthetic pathway for the membrane phospholipid phosphatidylcholine, an essential pathway in the Leishmania parasitic protozoan. Commonly used methods for kinetically quantifying the enzyme include a radioisotope assay utilizing labeled choline and a coupled spectrophotometric assay with multiple enzymes and substrates that indirectly measures choline kinase activity. When testing potential inhibitors with the coupled assay, results can cast doubt on whether choline kinase is being inhibited or one of the coupled enzymes. Therefore, 31P NMR spectroscopy was used to quantitatively measure the formation of the key product, phosphocholine, and to evaluate choline kinase activity. Interrogation of 31P NMR spectroscopy offers a number of benefits. Since this isotope is 100% abundant and has a relatively large gyromagnetic ratio, it is considered one of the more sensitive nuclides. As such, the need for costly isotopic enriched phosphorous is not required and detection of the 31P signal is possible even at relatively low concentrations. The enzymatic activity of Leishmania infantum choline kinase was able to be directly measured via integration of the 31P resonance associated with the phosphocholine product (δ = 3.94 ppm). These initial studies reveal that a 31P NMR spectroscopic-based assay could be used for testing substrate or transition state analogs as competitive inhibitors of Leishmania choline kinase that may prevent phosphatidylcholine synthesis in the parasite.