Search

Abstract Background Standard tibial motor nerve conduction measures are established with recording from the abductor hallucis. This technique is often technically challenging and clinicians have difficulty interpreting the information particularly in the short segment needed to assess focal tibial nerve entrapment at the medial ankle as occurs in posterior tarsal tunnel syndrome. The flexor hallucis brevis (FHB) has been described as an alternative site for recording tibial nerve function in those with posterior tarsal tunnel syndrome. Normative data has not been established for this technique. This pilot study describes the technique in detail. In addition we provide reference values for medial and lateral plantar orthodromic sensory measures and assessed intrarater reliability for all measures. Methods Eighty healthy female participants took part, and 39 returned for serial testing at 4 time points. Mean values ± SD were recorded for nerve conduction measures, and coefficient of variation as well as intraclass correlation coefficients (ICC) were calculated. Results Motor latency, amplitude and velocity values for the FHB were 4.1 ± 0.9 msec, 8.0 ± 3.0 mV and 45.6 ± 3.4 m/s, respectively. Sensory latencies, amplitudes, and velocities, respectively, were 2.8 ± 0.3 msec, 26.7 ± 10.1 μV, and 41.4 ± 3.5 m/s for the medial plantar nerve and 3.2 ± 0.5 msec, 13.3 ± 4.7 μV, and 44.3 ± 4.0 msec for the lateral plantar nerve. All values demonstrated significant ICC values (P ≤ 0.007). Conclusion Motor recording from the FHB provides technically clear waveforms that allow for an improved ability to assess tibial nerve function in the short segments used to assess tarsal tunnel syndrome. The reported means will begin to establish normal values for this technique.

A diagnostic characteristic of stingrays in the family Dasyatidae is the presence of a defensive, partially serrated spine located on the tail. We assessed the contribution of caudal spine morphology on puncture and withdrawal performance from two congeneric, co-occurring stingrays, the Atlantic stingray, Hypanus sabinus, and the bluntnose stingray, Hypanus say. Spines exhibited a high degree of morphological variability. Stingray spines were serrated along 50.8% (H. sabinus) or 62.3% (H. say) of their length. Hypanus say had a greater number of serrations along each side of the spine (30.4) compared with H. sabinus (20.7) but the pitch did not differ between species. We quantified spine puncture and withdrawal forces using porcine skin as a model for human skin. Puncture and withdrawal forces did not differ significantly between species, or within H. say, but withdrawal force was greater than puncture force for H. sabinus. We incorporated micro-computed tomography scanning to quantify tissue mineral density and found that for both species, the shaft of the spine was more heavily mineralized than the base, and midway (50%) along the length of the spine was more heavily mineralized than the tip. The mineralization variability along the spine shaft may create a stiff structure that can fracture once embedded within the target tissue and act as an effective predator deterrent., (© The Author(s) 2021. Published by Oxford University Press on behalf of the Society for Integrative and Comparative Biology.)

Puncture mechanics can be studied in the context of predator-prey interactions and provide bioinspiration for puncture tools and puncture-resistant materials. Lionfish have a passive puncture system where venomous spines (dorsal, anal, and pelvic), the tool, may embed into a predator's skin, the target material, during an encounter. To examine predator-prey interactions, we quantified the puncture performance of red lionfish, Pterois volitans , spines in buccal skin from two potential predators and porcine skin, a biological model for human skin. We punctured dorsal, anal, and pelvic lionfish spines into three regions of buccal skin from the black grouper ( Mycteroperca bonaci ) and the blacktip shark ( Carcharhinus limbatus ), and we examined spine macro-damage (visible without a microscope) post puncture. Lionfish spines were more effective, based on lower forces measured and less damage incurred, at puncturing buccal skin of groupers compared to sharks. Anal and dorsal spines incurred the most macro-damage during successful fish skin puncture trials, while pelvic spines did not incur any macro-damage. Lionfish spines were not damaged during porcine skin testing. Anal spines required the highest forces, while pelvic spines required intermediate forces to puncture fish skin. Dorsal spines required the lowest forces to puncture fish skins, but often incurred macro-damage of bent tips. All spine regions required similar forces to puncture porcine skin. These data suggest that lionfish spines may be more effective at puncturing humans such as divers than potential fish predators. These results emphasize that puncture performance is ultimately determined by both the puncture tool and target material choice. Lionfish puncture performance varies among spine region, when taking into account both the puncture force and damage sustained by the spine., (© The Author(s) 2021. Published by Oxford University Press on behalf of the Society for Integrative and Comparative Biology.)

The red lionfish, Pterois volitans , an invasive species, has 18 venomous spines: 13 dorsal, three anal and one on each pelvic fin. Fish spines can have several purposes, such as defense, intimidation and anchoring into crevices. Instead of being hollow, lionfish spines have a tri-lobed cross-sectional shape with grooves that deliver the venom, tapering towards the tip. We aimed to quantify the impacts of shape (second moment of area) and tapering on the mechanical properties of the spine. We performed two-point bending at several positions along the spines of P. volitans to determine mechanical properties (Young's modulus, elastic energy storage and flexural stiffness). The short and recurved anal and pelvic spines are stiffer and resist bending more effectively than the long dorsal spines. In addition, mechanical properties differ along the length of the spines, most likely because they are tapered. We hypothesize that the highly bendable dorsal spines are used for intimidation, making the fish look larger. The stiffer and energy-absorbing anal and pelvic spines are smaller and less numerous, but they may be used for protection as they are located near important internal structures such as the swim bladder. Lastly, spine second moment of area varies across the Pterois genus. These data suggest there may be morphological and mechanical trade-offs among defense, protection and intimidation for lionfish spines. Overall, the red lionfish venomous spine shape and mechanics may offer protection and intimidate potential predators, significantly contributing to their invasion success., (© 2019. Published by The Company of Biologists Ltd.)

A young adult feral cat presented to the Champaign County Humane Society with a subcutaneous mass near the stifle. The mass was aspirated. Chains of paired cocci organisms were identified, consistent with Dermatophilus congolensis. The identity of these organisms was confirmed by culture and polymerase chain reaction., (© ISFM and AAFP 2014.)