Hiroaki Hirotani

Effects of Mevastatin on Grafted Bone in MRL/MpJ Mice

Statins, lipid-lowering drugs, have been reported to influence bone metabolism. However, the available information about their effects on bone formation and resorption in vivo is still limited. The present study was undertaken to determine whether the topical administration of mevastatin could increase the bone mass of isografted bone. The tibiae were bilaterally dissected from a donor MRL/MpJ mouse and transplanted subcutaneously in the dorsal region of a recipient mouse. One grafted tibia was topically infused for either 1, 2, 3, or 4 weeks with mevastatin, using an osmotic minipump at a dose of 2.5 pmol/hr. The other tibia was infused with 0.9% NaCl (control). Our three results were: (1) Topical mevastatin stimulated bone formation and numerous cuboidal osteoblasts appeared on the surface of newly formed bone. Bone mineral density and bone area in mevastatin-treated bone were significantly increased. (2) Topical mevastatin increased the number of osteoclasts. (3) The expression of bone morphogenetic protein-2 (BMP-2) mRNA and receptor activator of NF-kB ligand (RANKL) mRNA were upregulated in mevastatin-treated bone. These results suggest that the topical infusion of mevastatin increases bone mass of isografted bone by increasing bone turnover and, at least in part, by promoting the expression of BMP-2 and RANKL mRNA.

Clinical Features of Idiopathic Parotid Pain Triggered by the First Bite in Japanese Patients with Type 2 Diabetes: A Case Study of Nine Patients

Objective First bite syndrome, characterized by pain in the parotid region after the first bite of each meal, predominantly develops in patients who have had head and neck surgery. Idiopathic parotid pain (IPP) that mimics first bite syndrome may present in patients without a history of surgery or evidence of an underlying tumor, but its clinical features are unclear. This study characterized the clinical characteristics of IPP in patients with diabetes. Study Design A retrospective case review involving the clinical findings and pain characteristics of nine patients with IPP and diabetes who presented to our department between 2013 and 2016. Results All the patients were men diagnosed with type 2 diabetes (median age, 43 years). IPP developed unilaterally in seven patients and bilaterally in two. The median intensity of the first bite pain was 8 on a numerical rating scale of 0–10. The trigger factor was gustatory stimuli, and the trigger area was the posterior section of the tongue. Postprandial pain occurred within 1–10 min after meals in six patients. Conclusions IPP may be considered a separate disorder, in which the pain characteristics are similar to those of first bite syndrome but the clinical features and pathophysiology are different.