Gen-yuki Yamane

Cortical Regulation During the Early Stage of Initiation of Voluntary Swallowing in Humans

The aim of the present study was to reveal the spatiotemporal relations among cortical regions involved in the initiation of voluntary swallowing in humans using magnetoencephalography (MEG). As a control task, finger extension movement, which is purely voluntary, was also investigated using the same techniques. The swallowing-related activity was distributed widely for 2000 ms before the electromyogram onset of the right suprahyoid muscle; however, the finger-related activity occurred in the late stage of the recording. The cingulate cortex, the insula, and the inferior frontal gyrus were the main loci active prior to swallowing. These cortical loci coincide with those suggested by previous human brain mapping studies that investigated the brain mechanism which controls swallowing. Activation in the cingulate cortex was registered in the early stage of swallowing and could be related to the cognitive process regarding the food being safe to swallow. The activation in the insula lasted for a long time before the initiation of swallowing. This suggests that the long-lasting activation in the insula prior to swallowing is essential for the initiation of swallowing.

Detection of periodontal bacteria in thrombi of patients with acute myocardial infarction by polymerase chain reaction.

BACKGROUNDS Numerous reports have demonstrated that periodontal bacteria are present in plaques from atherosclerotic arteries. Although periodontitis has recently been recognized as a risk factor for coronary artery disease, the direct relationship between periodontal bacteria and coronary artery disease has not yet been clarified. It has been suggested that these bacteria might contribute to inflammation and plaque instability. We assumed that if periodontal bacteria induce inflammation of plaque, the bacteria would be released into the bloodstream when vulnerable plaque ruptures. To determine whether periodontal bacteria are present in thrombi at the site of acute myocardial infarction, we tried to detect periodontal bacteria in thrombi of patients with acute myocardial infarction by polymerase chain reaction (PCR). METHODS We studied 81 consecutive adults with ST-segment elevation acute myocardial infarction who underwent primary percutaneous coronary intervention (PCI). All patients underwent removal of thrombus with aspiration catheters at the beginning of percutaneous coronary intervention, and a small sample of thrombus was obtained for PCR. RESULTS The detection rates of periodontal bacteria by PCR were 19.7% for Aggregatibacter actinomycetemcomitans, 3.4% for Porphyromonas gingivalis, and 2.3% for Treponema denticola. CONCLUSIONS Three species of periodontal bacteria were detected in the thrombi of patients with acute myocardial infarction. This raises the possibility that such bacteria are latently present in plaque and also suggests that these bacteria might have a role in plaque inflammation and instability.

Investigation of environmental factors for diagnosing malignant potential in oral epithelial dysplasia

A study was conducted in rats with early tongue carcinoma induced by 4-nitroquinoline 1-oxide (4NQO), in order to investigate the early diagnosis of malignant potential of epithelial dysplasia. The rat tongue lesions were classified by their severity into three groups corresponding to early cancer, dysplasia and no change. The grade of epithelial changes was determined according to 13 items of WHO Epithelial Dysplasia Criteria. The expression levels of p53 and Bcl-2 proteins were detected immunohistochemically, and apoptotic cells were detected using the TUNEL method. In addition, a p53 mutation by lesions was detected. The expression ratio of p53 protein was high in dysplasia, and the ratio of Bcl-2 protein was high in early cancer and dysplasia. The TUNEL-positive cells were observed primarily in the granular layers of the no change cells, and their numbers decreased as the cells shifted to the early cancer stage. The p53 mutation was detected using a microdissection method in dysplasia, where it was found in three out of nine lesions. All the mutations in dysplasia detected were on the same codon that was found to be mutated in the early cancer. These results indicate that the association between the p53 mutation and histological changes in carcinogenesis epithelial dysplasia is strong, and that both the identification of p53- and Bcl-2-positive epithelium, and decrease in the TUNEL positive ratio, were useful for the diagnosis of the malignant potential of precancerous lesions.

Factors affecting independence in eating among elderly with Alzheimer's disease

Aim:  In elderly patients with dementia, disturbed eating behavior is understood to be a core symptom or a behavioral and psychological symptom of dementia (BPSD). The purpose of the present study was to investigate the factors affecting self‐feeding in elderly patients with Alzheimers disease (AD).

Possible Role of Nitric Oxide in Radiation-Induced Salivary Gland Dysfunction

Abstract Takeda, I., Kizu, Y., Okamoto, Y., Saito, I. and Yamane, G. Possible Role of Nitric Oxide in Radiation-Induced Salivary Gland Dysfunction. Radiat. Res. 159, 465–470 (2002). In this study, we developed a murine model of xerostomia to elucidate the mechanism of radiation-induced salivary gland dysfunction and determined the levels of nitric oxide (NO) in the salivary glands to assess its involvement in the salivary dysfunction induced by radiation. In addition, an inhibitor of NO synthesis was administered to the model in vivo, and its effect on saliva secretion was investigated. Salivary gland irradiation at a dose of 15 Gy caused a significant decrease in secretion compared to unirradiated salivary glands. There were no marked differences between the irradiated mice and unirradiated mice in water or food consumption or in body weight changes. The NO levels in the cultured salivary gland epithelial cells were increased by treatment with a combination of interferon γ (Ifng), interleukin β (Il1b), and tumor necrosis factor α (Tnfa). Irradiation increased the NO level in the salivary gland tissue. The presence of NG-monomethyl-l-arginine acetate (l-NMMA), an inhibitor of NO synthesis, caused a decrease in the NO level in cultured salivary gland tissues after irradiation. Administration of l-NMMA to irradiated mice improved saliva secretion. These results suggest that excessive production of NO induced by radiation is involved in the formation of radiation-induced xerostomia. The finding that administration of an inhibitor of NO synthesis ameliorated the dysfunction of irradiated salivary glands indicates that NO plays a role as a mediator of the dry mouth symptoms that occur after irradiation.

Repair of the mandibular nerve by autogenous grafting after partial resection of the mandible

Ten patients who had ameloblastoma of the mandible underwent surgery for resection of the tumor followed by immediate mandibular reconstruction with free autogenous nerve grafting using the greater auricular nerve. One year after surgery pain perception and tactile sensibility were completely restored in eight of the ten patients.

Biomechanical three-dimensional finite-element analysis of maxillary prostheses with implants. Design of number and position of implants for maxillary prostheses after hemimaxillectomy.

The present study analyzed stress distributions in craniofacial structures around implant-supported maxillary prostheses. Using post-hemimaxillectomy computed tomography (CT) of a patient, the authors constructed a three-dimensional (3D) solid model using Digital Imaging and Communications in Medicine data (DICOM data) for maxillofacial and cranial bones. The effects of different prosthesis designs on stress distributions in craniofacial bones and osseous tissues around the implants were biomechanically investigated using 3D finite-element analysis. Maxillary prostheses were designed with 2 implants in the zygoma on the affected side and 2-3 implants in the maxillary alveolar bone on the unaffected side, without using a cantilever. Zygomatic implants provided suitable stress dispersal to the zygomatic and craniofacial bones on the affected side. This information is useful for designing maxillary prostheses.

Detecting signs of dysphagia in patients with Alzheimer's disease with oral feeding in daily life

It is important to understand dysphagia in patients with dementia, as it is associated with malnutrition and aspiration pneumonia. Particularly in patients with Alzheimers disease (AD), mortality from pneumonia is high and accounts for 70% of the causes of death. However, the standard swallowing tests are often difficult to use for patients with dementia, and methods to assess daily swallowing function are required. Therefore, the purpose of the present study was to identify signs of dysphagia in AD patients in daily life.

Metastatic malignant ameloblastoma of the kidneys

Ameloblastoma is an uncommon disease in the urological field. The resulting tumors or cysts are of odontogenic epithelial origin, are usually benign in nature and rarely metastasize to distant organs. We describe a case of metastatic ameloblastic carcinoma in both kidneys of a 38‐year‐old Japanese man, who had a history of malignant ameloblastoma and was referred to us for evaluation because of gross hematuria and left flank pain. Computed tomography showed irregular cystic masses in both kidneys. After we confirmed that the primary lesion and the lung metastatic lesion had not recurred, we treated the patient surgically. Approximately 4 months postoperatively the patient suffered a local recurrence of tumors that was very invasive and aggressive. The patient died 2 months later and the autopsy showed local metastasis only, without any metastatic lesion in the lungs or other organs. The present case showed that malignant ameloblastoma is highly aggressive, and in the case of metastases the prognosis is usually extremely poor.

Expression of β-catenin in rat oral epithelial dysplasia induced by 4-nitroquinoline 1-oxide

The aim of this study was to evaluate whether β-catenin accumulation is useful for diagnosing the malignant potential of oral precancerous lesions. We investigated oral epithelial dysplasia adjacent to early cancer induced by 4-nitroquinoline 1-oxide in rats. Localization of β-catenin and cell proliferation were detected immunohistochemically, and exon 3 of the β-catenin gene was analyzed. Accumulation of β-catenin in the cytoplasm and nucleus was evident in 10 of 16 dysplasia lesions. Since almost all of the dysplastic lesions in these rats transformed to invasive cancer, β-catenin accumulation may contribute to the early stage of carcinogenesis. The Ki-67 labeling index was significantly higher in dysplasia and early cancer than in no change. However, there were no significant differences between the expression patterns of β-catenin protein, suggesting that other proliferation pathways are involved in the early stage of tumor development in addition to β-catenin accumulation. No mutations of exon 3 of the β-catenin gene were detected in any of the dysplasia or early cancer lesions. These findings suggested that β-catenin accumulation in the cytoplasm and nucleus without mutation of exon 3 is an early event during carcinogenesis in this tongue cancer model.