Injury of the Hyoid Bone as a Rare Complication in Cervical Spine Rehabilitation: A Case Report.

Neck pain is a common reason for primary care visits, and its differential diagnosis should consider various conditions. The reported incidence of hyoid bone fractures is extremely low, accounting for only 0.002% of all fractures. The most common causes of hyoid bone fractures include strangulation attempts and motor vehicle accidents. We report a case of an uncommon complication of manual therapy of the cervical spine. A 76-year-old woman complained of neck pain that worsened during speaking and swallowing, originating from a neck physiotherapy session. The otolaryngological examination revealed tenderness on the right side of the neck. Flexible nasal endoscopy demonstrated a shallow right piriform recess and asymmetry of the arytenoid cartilages. Computer tomography scan of the neck showed an isolated fracture of the right greater horn (cornu major) of the hyoid bone. The treatment was nonsurgical, with the use of a Schantz collar and pain relief drugs. Reported symptoms of hyoid bone fractures include dysphagia, odynophagia, and neck pain. In most cases of hyoid fractures, conservative management suffices, involving rest, analgesic and anti-inflammatory treatment, and neck immobilization. Surgical treatment is often necessary in the cases of fractures accompanying other injuries.

Diacylglycerol kinase-ε is S-palmitoylated on cysteine in the cytoplasmic end of its N-terminal transmembrane fragment.

Diacylglycerol kinase-ε (DGKε) catalyzes phosphorylation of diacylglycerol to phosphatidic acid with a unique specificity toward 1-stearoyl-2-arachidonoyl-sn-glycerol, which is a backbone of phosphatidylinositol (PI). Owing to this specificity, DGKε is involved in the PI cycle maintaining the cellular level of phosphorylated PI derivatives of signaling activity and was also found crucial for lipid metabolism. DGKε dysfunction is linked with the development of atypical hemolytic uremic syndrome (aHUS) and possibly other human diseases. Despite the DGKε significance, data on its regulation by cotranslational and/or post-translational modifications are scarce. Here, we report that DGKε is S-palmitoylated at Cys38/40 (mouse/human DGKε) located in the cytoplasmic end of its N-terminal putative transmembrane fragment. The S-palmitoylation of DGKε was revealed by metabolic labeling of cells with a palmitic acid analogue followed by click chemistry and with acyl-biotin and acyl-polyethylene glycol exchange assays. The S-acyltransferases zDHHC7 (zinc finger DHHC domain containing) and zDHHC17 and the zDHHC6/16 tandem were found to catalyze DGKε S-palmitoylation, which also increased the DGKε abundance. Mouse DGKε-Myc ectopically expressed in human embryonic kidney 293 cells localized to the endoplasmic reticulum where zDHHC6/16 reside and in small amounts also to the Golgi apparatus where zDHHC7 and zDHHC17 are present. The Cys38Ala substitution upregulated, whereas hyperpalmitoylation of wild-type DGKε reduced the kinase activity, indicating an inhibitory effect of the Cys38 S-palmitoylation. In addition, the substitution of neighboring Pro31 with Ala also diminished the activity of DGKε. Taken together, our data indicate that S-palmitoylation can fine-tune DGKε activity in distinct cellular compartments, possibly by affecting the distance between the kinase and its substrate in a membrane.