PubMed Health⌕ Search

Biomedical subjects

Satoru Yamada

Publications and source records attributed to Satoru Yamada.

43 records · Page 3Linked to original sources
PubMed2002

Behavior of epithelial root sheath during tooth root formation in porcine molars: TUNEL, TEM, and immunohistochemical studies.

The behavior of epithelial cells during tooth root formation in porcine molars was investigated using TUNEL, immunohistochemical and transmission electron microscopic methods. Cells of Hertwig's epithelial root sheath (HERS) expressed bcl-2, but were TUNEL-negative. Epithelial cells of HERS were tightly connected and surrounded by a continuous basement membrane. When dental papilla cells were attached to the inner HERS, they became positive for osteopontin (OPN). The inner basement membrane was intermittent immediately after those cells started to synthesize dentin matrix, and the intercellular spaces of the HERS became wider. Dental sac cells then migrated between the fragmented HERS and were directly connected to epithelial cells by desmosome-like structures. After the cementum was synthesized by these mesenchymal cells, epithelial cells aggregated to form cell clusters, which were again surrounded by a continuous basement membrane. These results suggest that fragmentation of the HERS is due to the invasion of dental sac cells, but is not related to cell death. Furthermore, the differentiation of dental papilla cells into odontoblasts occurred following their connection to the HERS through the basement membrane. Moreover, it is suggested that the differentiation of dental sac cells into cementoblasts occurred upon their direct connection to epithelial cells of the HERS.

Animals↗
PubMed2002

Diagnosis of vasospastic angina by hyperventilation and cold-pressor stress echocardiography: comparison to I-MIBG myocardial scintigraphy.

OBJECTIVES: We assessed the usefulness of hyperventilation and cold-pressor stress echocardiography in the diagnosis of vasospastic angina compared with that of iodine-123 metaiodobenzylguanidine (123I-MIBG) myocardial scintigraphy. BACKGROUND: Various noninvasive methods have been used to detect vasospastic angina, but they are not very sensitive in the diagnosis of vasospastic angina. 123I-MIBG images and stress echocardiography have recently been proposed as a useful tool for detecting vasospastic angina. METHOD: Thirty patients (21 males and 9 females, mean age: 52 +/- 14 years) who complained of rest angina were enrolled for this study. The hyperventilation and cold-pressor stress echocardiography test consisted of hyperventilation for 6 minutes, followed by cold water pressor for 2 minutes under continuous electrocardiographic and echocardiographic monitoring. Left ventricular regional wall motion by echocardiogram was analyzed by using the 16-segment model, and wall motion ranging from normokinesis to dyskinesis was evaluated visually in each segment. Single-photon emission computed tomography images of 123I-MIBG myocardial scintigraphy were divided into 26 segments. Defect scores were established using the 4 grades. The echocardiographic criteria for coronary spasm was worsening wall motion and the scintigraphic criteria was defect score more than moderately reduced. Acetylcholine was selectively injected into the right coronary artery (20 microg and 50 microg) and left coronary artery (20 microg, 50 microg, and 100 microg). RESULTS: Of 30 patients, 20 patients had coronary spasm on coronary angiography with an intracoronary injection of acetylcholine, whereas 10 patients showed no spasm. Multivessel spasms were observed in 15 patients. Sensitivity, specificity, positive predictive value, negative predictive value, and diagnostic accuracy of hyperventilation and cold-pressor stress echocardiography for diagnosing in patients with vasospastic angina were 90%, 90%, 95%, 82%, and 90%, respectively. However, those of 123I-MIBG myocardial scintigraphy for diagnosing in patients with vasospastic angina were 90%, 40%, 75%, 67%, and 73%, respectively. The specificity of hyperventilation and cold-pressor stress echocardiography was significantly higher than that of 123I-MIBG myocardial scintigraphy (P <.05). CONCLUSION: The specificity of hyperventilation and cold-pressor stress echocardiography in diagnosing coronary spasm were higher than that shown by 201I-MIBG myocardial scintigraphy.

3-Iodobenzylguanidine↗
PubMed2002

Reduced expression of tissue inhibitor of metalloproteinase (TIMP)-2 in gestational trophoblastic diseases.

To elucidate the involvement of type IV collagenases [matrix metalloproteinase (MMP)-2 and MMP-9] and their tissue inhibitors (TIMP-1 and TIMP-2) in the development of gestational trophoblastic disease (GTD), we quantified their levels in hydatidiform mole and choriocarcinoma tissues using specific enzyme-linked immunosorbent assays, and the results were compared with those from normal first trimester placenta. Levels of pro-MMP-2 were increased in hydatidiform mole, and they were further elevated in choriocarcinoma. Levels of pro-MMP-9 in choriocarcinoma and those of TIMP-1 in both hydatidiform mole and choriocarcinoma were also increased. In contrast, TIMP-2 levels were markedly decreased in both hydatidiform mole and choriocarcinoma. Similar results were obtained by the tissue culture of first trimester placenta and hydatidiform mole. Gelatin zymography indicated that the levels of both pro- and activated forms of MMP-2 and MMP-9 were higher in hydatidiform mole and choriocarcinoma. The decreased expression of TIMP-2 in hydatidiform mole and choriocarcinoma was confirmed by Western blot, Northern blot and immunohistochemistry, with the decrease being more pronounced in choriocarcinoma. Taken together, the present study shows that both TIMP-2 mRNA and protein levels are markedly decreased in GTD and the imbalance of MMP-TIMP production, shifted toward greater MMP activity, may be involved in the pathogenesis of GTD.

Choriocarcinoma↗
PubMed2002

High frequency of valpha24(+) vbeta11(+) T-cells observed in type 1 diabetes.

OBJECTIVE: Natural killer T-cells (NKT cells) are believed to play an important role in the regulation of immune response, and a numerical and functional deficit of NKT cells has been reported to be associated with the pathogenesis of autoimmune diseases. Thus far, it has been shown that subjects with type 1 diabetes have a lower frequency of NKT cells than nondiabetic subjects. In this study, we measured the frequency of peripheral Valpha24(+) Vbeta11(+) T-cells, which include human NKT cells, in Japanese diabetic patients. RESEARCH DESIGN AND METHODS: Peripheral blood samples were obtained from 164 Japanese diabetic patients and 67 healthy subjects. The diabetic patients were classified into four categories as follows: islet-associated autoantibody-positive (Ab(+)) and -negative (Ab(-)) classic type 1 diabetes, latent autoimmune diabetes in adults (LADA), and type 2 diabetes. We measured the frequency of peripheral Valpha24(+) Vbeta11(+) CD3(+) triple-positive cells. RESULTS: Unexpectedly, a higher frequency of Valpha24(+) Vbeta11(+) T-cells was observed in Ab(+) and Ab(-) patients compared with LADA patients (P = 0.0294 and P = 0.0021), type 2 diabetic patients (P < 0.0001 and P < 0.0001), and healthy subjects (P = 0.0046 and P = 0.0001). Moreover, an inverse correlation between Valpha24(+) Vbeta11(+) T-cell frequency and disease duration was observed in Ab(+) (rho = -0.455; P = 0.0023) and Ab(-) (rho = -0.432; P = 0.0162) patients. CONCLUSIONS: Our findings indicate that a high frequency of Valpha24(+) Vbeta11(+) T-cells is a unique finding in recent-onset classic type 1 diabetes, and measurement of Valpha24(+) Vbeta11(+) T-cell frequency may be useful to assess the disease activity of classic type 1 diabetes.

Adult↗
PubMed2002

[Quadricuspid pulmonary valve with valvular stenosis and regurgitation identified by transthoracic echocardiography: a case report].

A 74-year-old man was admitted to our hospital complaining of dyspnea. Parasternal transthoracic echocardiography showed a quadricuspid pulmonary valve above the aortic valve and a hypoplastic accessory cusp between the right and left cusps of the pulmonary valve. The pulmonary valve ring diameter was normal (26 mm) but the transvalvular peak velocity was 3.5 m/sec, suggesting a pressure gradient of 49 mmHg across the pulmonary valve. The pulmonary valve had thickening and decrease in mobility of the leaflets without complete closure during diastole, and severe pulmonary regurgitation was present. Heart failure was treated successfully with digitalis and diuretics. Quadricuspid pulmonary valve is difficult to identify using transthoracic echocardiography because of the anatomical features. In this case, the dilated main pulmonary artery caused the pulmonary valve orifice to shift anteriorly, allowing visualization of the short-axis view of the pulmonary valve.

Aged↗
PubMed2002

Effect of porous xenographic bone graft with collagen barrier membrane on periodontal regeneration.

The purpose of this study was to investigate the effect of porous xenographic bone graft (Bio-Oss) with a collagen barrier membrane (Bio-Gide) on formation of new cementum and new bone in experimental intrabony defects of dogs. The intrabony defects were treated by either guided tissue regeneration with the collagen membrane (control group) or the collagen membrane with the porous bone mineral graft (experimental group). After 8 weeks, the animals were sacrificed and the tissues were histologically examined. New cementum with inserting collagen fibers was observed on the exposed surfaces in both groups. The amount of nevv bone was significantly greater in the group using the bone graft with the membrane than in the control group. The use of the collagen barrier membrane in combination with the porous bone graft material may enhance new bone and cementum formation.

Absorbable Implants↗