Head CT Guidelines Following Concussion Among the Youngest Trauma Patients: Can We Limit Radiation Exposure Following Traumatic Brain Injury?

Introduction. Recent studies have provided guidelines on the use ofhead computed tomography (CT) scans in pediatric trauma patients.The purpose of this study was to identify the prevalence of theseguidelines among concussed pediatric patients. Methods. A retrospective review was conducted of patients fouryears or younger with a concussion from blunt trauma. Demographics,head injury characteristics, clinical indicators for head CT scan(severe mechanism, physical exam findings of basilar skull fracture,non-frontal scalp hematoma, Glasgow Coma Scale score, loss ofconsciousness, neurologic deficit, altered mental status, vomiting,headache, amnesia, irritability, behavioral changes, seizures, lethargy),CT results, and hospital course were collected. Results. One-hundred thirty-three patients (78.2%) received a headCT scan, 7 (5.3%) of which demonstrated fractures and/or bleeds. Allpatients with skull fractures and/or bleeds had at least one clinicalindicator present on arrival. Clinical indicators that were observedmore commonly in patients with positive CT findings than in thosewith negative CT findings included severe mechanism (100% vs.54.8%, respectively, p = 0.020) and signs of a basilar skull fracture(28.6% vs. 0.8%, respectively, p = 0.007). Severe mechanism alonewas found to be sensitive, but not specific, whereas signs of a basilarskull fracture, headache, behavioral changes, and vomiting were specific,but not sensitive. No neurosurgical procedures were necessary,and there were no deaths. Conclusions. Clinical indicators were present in patients with positiveand negative CT findings. However, severe mechanism of injuryand signs of basilar skull fracture were more common for patients withpositive CT findings. Kans J Med 2018;11(2):38-43

Deterrent activities in the crude lipophilic fractions of Antarctic benthic organisms: chemical defences against keystone predators

Generalist predation constitutes a driving force for the evolution of chemical defences. In the Antarctic benthos, asteroids and omnivore amphipods are keystone opportunistic predators. Sessile organisms are therefore expected to develop defensive mechanisms mainly against such consumers. However, the different habits characterizing each predator may promote variable responses in prey. Feeding-deterrence experiments were performed with the circumpolar asteroid macropredator Odontaster validus to evaluate the presence of defences within the apolar lipophilic fraction of Antarctic invertebrates and macroalgae. A total of 51% of the extracts were repellent, yielding a proportion of 17 defended species out of the 31 assessed. These results are compared with a previous study in which the same fractions were offered to the abundant circum-Antarctic amphipod Cheirimedon femoratus. Overall, less deterrence was reported towards asteroids (51%) than against amphipods (80.8%), principally in sponge and algal extracts. Generalist amphipods, which establish casual host–prey sedentary associations with biosubstrata (preferentially sponges and macroalgae), may exert more localized predation pressure than sea stars on certain sessile prey, which would partly explain these results. The nutritional quality of prey may interact with feeding deterrents, whose production is presumed to be metabolically expensive. Although optimal defence theory posits that chemical defences are managed and distributed as to guarantee protection at the lowest cost, we found that only a few organisms localized feeding deterrents towards most exposed and/or valuable body regions. Lipophilic defensive metabolites are broadly produced in Antarctic communities to deter opportunistic predators, although several species combine different defensive traits