Biomedical subjects

Shinichi Yamada

Publications and source records attributed to Shinichi Yamada.

7 recordsLinked to original sources

PubMed2006

Application of virtual reality force feedback haptic device for oral implant surgery.

A novel support system for implant surgery was tried out, which involves manipulating a three-dimensional (3-D) computed tomography (CT) image of a jawbone with a virtual reality force feedback haptic device. Through this virtual system, the haptic experience of bone drilling with vibration and the sound of the contra-angle handpiece could be realized. It is expected to be useful for training inexperienced dentists and educating dental students. The simulation of oral implant insertion was also focused on. A simple cylindrical implant model was inserted into a 3-D image of the jawbone by operating the haptic device, with consideration of bone condition. A rectangular solid object that served as a bone-supported surgical template was adopted, and the shapes of the bone and the implant were subtracted from the object. In this manner, the CAD of the surgical template with impressions of the bone and the implant guide holes for insertion was realized. The surgical template was milled with a computer-controlled milling machine (CAM). Surgical template accuracy was examined with an edentulous gypsum bone model having six holes for implant insertion. Simulation of the oral implant insertion and CAD/CAM of the surgical template were conducted. The milled surgical template was fitted on the gypsum bone model, and CT images were taken. Cross-sections of the guide holes in the surgical template were imaged, and misalignment between the guide holes of the surgical template and the drilled holes on the jawbone was measured. The average misalignment is less than 0.2 mm, and it indicates that the present system is potentially applicable to oral implant surgery.

Computer-Aided Design↗

PubMed2006

[Labor management using epidural anesthesia in a gravida patient with high spinal injury].

Since autonomic hyperreflexia (AH) is a serious complication during labor in a gravida with spinal cord injury, anesthetic measures should be taken for the suppression of AH even in a sensory-loss condition. Several reports have described various methods for the suppression of AH, in which epidural anesthesia has been advocated as a useful means for the prevention or amelioration of AH. However, it is difficult to evaluate the efficacy of epidural anesthesia due to the lack of sensory and motor functions. We report a primipara who had spinal cord injury below the T 3 level at the age of 17 due to a traffic accident and underwent successful vaginal delivery twice under epidural anesthesia at the ages of 30 and 32. For the first delivery, we placed two epidural catheters. We controlled the rate and the content of epidural infusion through the two different injection sites so as to meet delivery process. For the second delivery we did epidural anesthesia in the same way. Tubal-ligation was also performed under epidural anesthesia after the second delivery. No major obstetric complication including AH occurred in either of delivery. The woman with high spinal injury could have two healthy children without major complications during labor by the cooperation of gynecologists and anesthesiologists.

Adult↗

PubMed2005

[Treatment strategy for malignant solid tumors in childhood].

The prognosis for children with malignant solid tumors has improved dramatically in Japan. During the last two decades, various groups have conducted sequential studies of the treatment of children with neuroblastoma, Wilms' tumor, and hepatoblastoma. Most institutes participated in nonrandomized trials designed to evaluate the safety and efficacy of combination chemotherapy, surgery, and radiotherapy in each group study and treated children with these tumors The results are reviewed and areas for future investigation are identified.

Antineoplastic Combined Chemotherapy Protocols↗

PubMed2004

Impaired endothelial responses in patients with deep hypothermic cardiopulmonary bypass.

We examined whether vascular endothelial function is impaired with deep hypothermia during cardiopulmonary bypass. Such impairment may cause the prolonged hypoperfusion of tissues or organs. Thirty adult patients were classified into three groups according to the degree of hypothermia during cardiopulmonary bypass; deep (DH: 18-20 degrees C, n = 10), moderate (MDH: 25-30 degrees C, n = 10) and mild (MLH: 32-34 degrees C, n = 10) hypothermia. A bolus dose of 100 mg acetylcholine was injected, followed by 1 mg nitroglycerine 20 min later under hypothermic cardiopulmonary bypass. Plasma concentrations of nitric oxide metabolites (NOx) and endothelin-1 were determined until the 7th post-operative day (POD). The reduction of arterial pressure after acetylcholine was the smallest in the DH group (-9 +/- 6 mmHg, p < 0.01). The time to reach the maximum reduction of arterial pressure was the longest in the DH group (acetylcholine: 47.7 +/- 23.6 sec, nitroglycerine: 53.4 +/- 21.4 sec, p < 0.01). NOx production was reduced until the 1st POD and then recovered. The recovery was more rapid in the MLH group than the other two groups (p < 0.01). The plasma endothelin-1 did not differ among the three groups. These results suggest that endothelial function is impaired during cardiopulmonary bypass with deep hypothermia.

Adult↗

PubMed2003

Biomechanical stress in bone surrounding an implant under simulated chewing.

The concept of reducing nonaxial loading of dental implants has been widely regarded as the standard procedure. The aim of this study was to reveal the biomechanical stress distribution in supporting bone around an implant and a natural tooth under chewing function. Three-dimensional finite element models of the mandibular first molar and the titanium implant both with the mandible in the molar region were constructed. The directions of displacement constraints were determined according to the angles of the closing pathways of chopping type and grinding type chewing patterns. The tooth model showed smooth stress distribution in the supporting bone with low stress concentration around the neck of the tooth. The implant model showed stress concentration in the supporting bone around the neck of the implant, especially in the buccal area. The grinding type model of the implant showed higher tensile stress concentration than the chopping type model at the lingual neck of the implant. The results of this study suggested the importance of considering occlusion under chewing function for understanding the biomechanics of oral implants.

Adult↗

PubMed2002

[Flat Panel Detector Philips introduced and its system direction].

We introduced digital X-ray diagnostic systems with Flat panel detector both in general X-ray systems and in Angiography systems. Our introduced Flat Panel Detector has the latest technology and has Cesium Iodide (CsI) that absorbs X-ray energy and generates visible light. Detected light signals make digital X-ray images. CsI is the most important material because its absorption rate of X-ray influences the strength of output digital signal. The purpose in this paper is checking that is latest Flat Panel Detector pulls out enough capability CsI has. Especially the thickness of CsI relates to X-ray absorption. X-ray absorption rate depended on the thickness of CsI was calculated by using simulated X-ray model and the future direction of Flat Panel Detector system was discussed.

Cesium↗

PubMedDate not supplied

Posterior shoulder pain in throwing athletes with a Bennett lesion: factors that influence throwing pain.

A Bennett lesion is a bony spur at the posterior glenoid that is often seen in baseball players and usually asymptomatic. However, it sometimes becomes painful, but the mechanism of throwing pain is still unknown. The purposes of this study were to identify clinical characteristics associated with the Bennett lesion causing shoulder pain (painful Bennett lesion) and to try to predict which type of Bennett lesion might become painful. Several clinical factors in 51 consecutive baseball players who underwent arthroscopic surgery were investigated. Of these baseball players, 24 had a bony spur: 13 were diagnosed as having a painful Bennett lesion and 11 were diagnosed as having an asymptomatic Bennett lesion, according to our previously reported criteria. The other 27 players did not have a bony spur. Posterior joint laxity, no deficit of internal rotation, and an avulsed fragment on computed tomography scan were determined to be the characteristic clinical features in the shoulders with a painful Bennett lesion.

Adolescent↗