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Objective Employ an automated indentation technique, using a commercially available machine, to assess the effect of fibroblast growth factor 2 (FGF2) expression on structural stiffness over the surface of both murine femoral articular cartilage (AC) and temporomandibular joint (TMJ) mandibular condylar cartilage (MCC). Design Experiments were performed using 3-month-old female homozygote Fgf2KO mice with wild type (WT) littermates. After euthanization, isolated mandibles and hindlimbs were either processed for histology or subjected to automated indentation on a Biomomentum Mach-1 v500csst with a 3-axis motion controller in a phosphate buffered saline bath using a 0.3 mm spherical tip indenter. The effect of indentation depth on normal force was characterized, then structural stiffness was calculated and mapped at multiple positions on the AC and MCC. Results Automated indentation of the AC and TMJ MCC was successfully completed and was able to demonstrate both regional variation in structural stiffness and differences between WT and Fgf2KO mice. Structural stiffness values for Fgf2KO AC were significantly smaller than WT at both the medial/anterior ( P < 0.05) and medial/posterior ( P < 0.05) positions. Global Fgf2KO also lead to a decrease in MCC thickness of the TMJ compared with WT ( P < 0.05) and increased structural stiffness values for Fgf2KO at both the posterior and anterior location ( P < 0.05). Conclusions Automated indentation spatially resolved differences in structural stiffness between WT and Fgf2KO tissue, demonstrating FGF2 expression affects femoral AC and TMJ MCC. This quantitative method will provide a valuable approach for functional characterization of cartilage tissues in murine models relevant to knee joint and TMJ health and disease.

Purposeof review: Kratom (mitragynine) is a commercially available herbal supplement that is gaining popularity in the United States (U.S.). Kratom is associated with a variety of neurological effects. This review will discuss kratoms association with seizure through three cases and highlight what neurologists should know about kratom's clinical effects and legal status.Recent findings:Kratom is currently commercially available, unscheduled by the U.S. Drug Enforcement Administration (DEA), and a topic of regulatory debate in the US. Large poison center reviews have suggested that kratom use is associated with seizure. There have been limited case studies to corroborate this finding. We present three cases in which seizures were associated with kratom use in patients treated for epilepsy.Summary:Since 2008, kratom use is rising in prevalence in the U.S. aided by lack of regulation. Neurologists need to be aware of its association with seizure and other neurologic side effects.

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