Intraobserver and Interobserver Reliability of the Peritubercle Lucency Sign in Slipped Capital Femoral Epiphysis.

BACKGROUND: An area of enlargement of the metaphyseal socket around the epiphyseal tubercle, termed the peritubercle lucency sign, has recently been introduced as a possible predictor of contralateral slipped capital femoral epiphysis in patients with previous unilateral slipped capital femoral epiphysis. This study aimed to assess intraobserver and interobserver reliability for detecting the presence or absence of the peritubercle lucency sign. METHODS: Thirty-five radiographs were presented to 6 fellowship-trained pediatric orthopaedic surgeons on 2 separate occasions 30 days apart, ensuring that the images were shown in a different order on the second exposure. Both times the reviewers recorded whether the peritubercle lucency sign was present or absent in each of the radiographs. Statistical analysis was performed to determine the intraobserver and interobserver reliability. RESULTS: In the intraobserver analysis, percent agreement between the first and second time the radiographs were reviewed varied between 62.9% and 85.7%, for an average intraobserver agreement of 74.8%. κ values for the 6 reviewers varied between 0.34 and 0.716, with an average intraobserver κ value of 0.508. The interobserver percent agreement was 40.0% for the first time the radiographs were reviewed, 42.9% the second time, and the overall interobserver percent agreement was 29%. The interobserver κ value was 0.44 the first time the radiographs were reviewed, 0.45 the second time, and the overall interobserver κ value was 0.45. DISCUSSION: On the basis of our findings, the peritubercle lucency has modest intraobserver and interobserver reliability at best and should be used with other currently used factors, such as age, presence of endocrinopathy, status of triradiate cartilage, posterior sloping angle, and modified Oxford score, in determining the need for prophylactic pinning. Further refinement of the definition of the peritubercle lucency sign may be needed to improve agreement and reliability of the sign. LEVEL OF EVIDENCE: Level III-prognostic study.

Pediatric Septic Arthritis: An Update.

Septic arthritis in children is a surgical emergency, and prompt diagnosis and treatment are mandatory. If diagnosed quickly and treated correctly, the outcomes can be good. With delay in diagnosis and without proper treatment, outcomes often are quite devastating, with growth disturbance and joint destruction.

Evolution of the antibiotic resistance protein, FosA, is linked to a catalytically promiscuous progenitor.

The fosfomycin (1) resistance proteins FosA and FosX in pathogenic microorganisms are related to a catalytically promiscuous progenitor encoded in a phn operon in Mesorhizobium loti. The mlr3345 gene product (FosX(Ml)) from M. loti has a very low epoxide hydrolase activity and even lower glutathione transferase activity toward 1 and does not confer resistance to the antibiotic. In vitro homologous recombination of the mlr3345 and pa1129 genes (a fosA gene from Pseudomonas aeruginosa that does confer robust resistance to 1) produces recombinant proteins that confer resistance to 1 and indicate that the FosA resistance proteins are functionally and genetically related to mlr3345.

A model for glutathione binding and activation in the fosfomycin resistance protein, FosA.

The genomically encoded fosfomycin resistance protein from Pseudomonas aeruginosa (FosA(PA)) utilizes Mn(II) and K(+) to catalyze the addition of glutathione (GSH) to C1 of the antibiotic rendering it inactive. Although this protein has been structurally and kinetically characterized with respect to the substrate, fosfomycin, questions remain regarding how the enzyme binds the thiol substrate, GSH. Computational studies have revealed a potential GSH binding site in FosA(PA) that involves six electrostatic or hydrogen-bonding interactions with protein side-chains as well as six additional residues that contribute van der Waals interactions. A strategically placed tyrosine residue, Y39, appears to be involved in the ionization of GSH during catalysis. The Y39F mutant exhibits a 13-fold reduction of catalytic activity (k(cat)=14+/-2s(-1)), suggesting a role in the ionization of GSH. Mutation of five other residues (W34, Q36, S50, K90, and R93) implicated in ionic of hydrogen-bonding interactions resulted in enzymes with reduced catalytic efficiency, affinity for GSH, or both. The mutant enzymes were also found to be less effective resistant proteins in the biological context of Escherichia coli. The more conservative W34H mutant has native-like catalytic efficiency suggesting that the imidazole NH group can replace the indole group of W34 that is important for GSH binding. In the absence of co-crystal structural data with the thiol substrate, these results provide important insights into the role of GSH in catalysis.