Microstructural and mechanical recovery of bone in ovariectomized rats: The effects of menaquinone-7.

The loss of bone quantity and quality in postmenopausal female patients can be a problem for dental treatment. A sufficient intake of nutrients such as calcium, magnesium, and vitamins D and K is likely correlated with the mechanical properties of bone. In particular, vitamin K2, also called menaquinone (MK), inhibits bone loss in postmenopausal women. Here we demonstrate the microstructural and mechanical properties of bone recovery in ovariectomized (OVX) rats during MK-7 administration. Bilateral ovariectomy and a sham operation were performed on 14-week-old female SPF Wistar rats. MK-4 and -7 were orally administered at 30 mg/kg daily for 12 weeks. The femur was used for the 3-point bending test and microstructural analysis of the cancellous bone by micro-CT, and the mandibular cortical bone for the evaluation of mechanical properties on a nanoscale. Micro-computed tomography revealed irregular trabecular architecture, hollow marrow cavities, and sparse trabecular bone in the femurs of the OVX group. Trabecular bone structure analysis showed that the MK-7 group had greater bone volume per tissue volume (BV/TV) and a higher trabecular number than the OVX group. The bulk-scale 3-point bending test did not allow the mechanical properties between OVX and OVX/MK7 groups to be discerned, yet at the smallest level, the elastic-plastic transition point of the nanoindentation stress-strain curve of the mandibular cortical bone was higher in the MK-7 group than in the OVX group. These findings suggest that MK-7 enables bone microstructural and mechanical recovery in the OVX model.

[Incident Analysis in Radiography Focusing on the Experience Period of Radiological Technologist].

We investigated the causes and trends of incidents related to radiography. From April 2014 to March 2016, 384 incident reports related to radiography were posted. We analyzed based on the nature of the incidents and the experience period of radiological technologist (RT). The types of incidents were 'Incorrect examination order by medical doctor' (50.0%), 'X-ray retake' (24%), 'Incorrect examination procedure' (9.9%), 'Fall or injury of the patient under examination' (3.6%), 'selection error of X-ray detector' (3.1%), 'patient mismatch' (1.8%), 'overdose' (1.3%), and 'others' (a malfunctioning device, trouble of systems and the other) (6.5%). There was no relationship between the number of incidents per person and the experience period as RT; (7.8/person for <3 years of experience, 9.7/person for 3-10 years, 6.4/person for 11-25 years of experience, 7.4/person for <25 years of experience). The experience period as RT are related to some types of incident reduction. 'Fall or injury of the patient under examination' and 'overdose' were more frequently reported by RTs of shorter experience (<3 years and 3-10 years of experience) than RTs of longer experience (11-25 years and <25 of experience). On the other hand, 'patient mismatch' and 'selection error of X-ray detector' were more frequently reported by RTs of long experience than RTs of short experience.