Biomedical subjects

Takashi Inoue

Publications and source records attributed to Takashi Inoue.

At least 91 records · Page 5Linked to original sources

PubMed2003

Oligocyclization of 2-(hydroxymethyl)pyrroles with electron-withdrawing groups at beta-positions: formation and structural elucidation of porphyrinogens and hexaphyrinogens.

Acid-catalyzed oligomerization of 2-(hydroxymethyl)pyrroles bearing C6F5, 2,6-Cl2C6H3, CF3 and CO2Et groups at beta-positions was examined. The reaction of ethyl pyrrole-3-carboxylates gave a mixture of oligomers and type I isomers of porphyrinogens and hexaphyrinogens were isolated when the other beta-substituents were sufficiently bulky, for example, mesityl, 2,6-Cl2C6H3 and C6F5 groups. On the other hand, the pyrroles having other electron-withdrawing groups afforded porphyrinogens as the only isolable products.

Journal Article↗

PubMed2003

High-field MRI of the central nervous system: current approaches to clinical and microscopic imaging.

Introduction of clinical high-field MRI has raised interest in the use of clinical imaging--the efficacy of which has not yet been fully established--in daily practice. A high signal-to-noise ratio and profound susceptibility effects can improve the spatial resolution and image contrast of clinical imaging, whereas the heating effects of the radio frequency tend to prolong acquisition time. As well, inhomogeneities in the static or local magnetic fields can have a negative effect on image quality. The T(1) prolongation may affect T(1) contrast yet improve the enhancement effect of gadolinium chelate and the inflow effect of MR angiography. High-contrast imaging, such as the short inversion-time inversion recovery technique, can provide excellent intra- and extracerebral contrast comparable to microscopic or macroscopic specimens. High-field systems can also be applied to microscopic imaging. High-field MRI is expected to have an increased clinical impact in the near future. Technological advances tailored to high-field systems, as well as the accumulation of scientific evidence, will be necessary to establish its predominance over conventional MRI.

Central Nervous System↗

PubMed2003

Regulatory mechanisms of periodontal regeneration.

The periodontal ligament, located between the cementum and the alveolar bone, has a width ranging from 0.15 to 0.38 mm. Regeneration and homeostasis of the periodontal ligament are highly significant functions in relation to periodontal therapy, tooth transplantation or replantation, and orthodontic tooth movement. The purpose of this review is to discuss the regulatory mechanisms of regenerative and homeostatic functions in the periodontal ligament based on currently published studies and also on our own experimental data. We consider the capability of the ligament tissue to promote or to suppress calcification in connection with bone and cementum formation and the maintenance of the periodontal ligament space. Also discussed are the involvement of the periodontal ligament tissue in the regenerative ability, cell proliferation, growth and differentiation factors, extracellular matrix proteins, homeostatic phenomena, function of Malassez epithelial rests, tooth movement, or occlusal loading. Regulatory mechanisms for regeneration and homeostasis of the periodontal ligament are hypothetically proposed.

Animals↗

PubMed2003

Functional characterization of the adenosine receptor contributing to glycogenolysis and gluconeogenesis in rat hepatocytes.

The adenosine receptor subtype mediating glucose production by glycogenolysis and gluconeogenesis was studied in primary cultured rat hepatocytes. Adenosine and adenosine agonists caused cyclic AMP accumulation in rat hepatocytes. The order of potency was 5'-N-ethylcarboxamidoadenosine (NECA)>R(-)-N(6)-(2-phenylisopropyl)adenosine (RPIA)>adenosine>2-[p-(carboxyethyl)phenylethylamino]-5'-N-ethylcarboxamidoadenosine (CGS21680). Furthermore, adenosine agonists stimulated glycogenolysis and gluconeogenesis. The order of potency was NECA>RPIA>CGS21680. The rank order of potency is typical for adenosine A(2B) receptors. Glycogenolysis stimulated by NECA was fully inhibited by nonselective adenosine antagonists, 9-chloro-2-(2-furanyl)[1,2,4]triazolo[1,5-c]quinazolin-5-amine (CGS15943). However, the adenosine A(2A) receptor-selective antagonist, 8-(3-chlorostyryl)caffeine (CSC), and the adenosine A(1) receptor-selective antagonist, (+)-(R)-[(E)-3-(2-phenylpyrazolo[1,5-alpha]pyridin-3-yl)acryloyl]-2-piperidine ethanol (FK453), had a low inhibitory potency. A strong correlation was found between the inhibitory effect of adenosine antagonists on NECA-induced glucose production and that on intracellular cyclic AMP generation in rat hepatocytes. Our results suggest that adenosine stimulates cyclic AMP formation and regulates glycogenolysis and gluconeogenesis, most likely through the adenosine A(2B) receptor subtype in rat hepatocytes.

Animals↗

PubMed2003

The attachment and growth behavior of osteoblast-like cells on microtextured surfaces.

In previous studies, we showed that the application of microgrooves on a surface can direct cellular morphology and the deposition of mineralized matrix of osteoblast-like cells (Biomaterials 20 (1999) 1293; Clin. Oral Impl Res. 11 (2000) 325). In this study, we evaluated the attachment and growth behavior of these cells, using scanning- and transmission electron microscopy (SEM/TEM). Smooth and microgrooved polystyrene substrates were made (groove depth 0.5-1.5 microm, groove- and ridge width 1-10 microm). On these substrates, osteoblast-like cells were cultured for periods up to 16 days. SEM showed that the cells, and their extensions, closely followed the surface on smooth and wider grooved (>5 microm) substrates. In contrast, narrow grooves (<2 microm) were bridged. After 16 days of incubation, the matrix showed extensive deposition of collagen fibrils, and the formation of calcified nodules. With TEM it was shown that on the smooth and wider grooved substrates, focal adhesions were spread throughout the surface. However, on narrow grooves focal adhesions were always positioned on the edges of surface ridges only. Apparently, most extracellular matrix (ECM) was produced by the cells that directly adhered to the substrate. Deposition of ECM was seen in the surface grooves, as well as in between the cell layers. On basis of the current study and previous experiments, we conclude that microgrooves are able to influence bone cell behavior by (1) determining the alignment of cells and cellular extensions, (2) altering the formation and placement of cell focal adhesions, and (3) altering ECM production. Therefore, microgrooved surfaces seem interesting to be applied on bone-anchored implants.

Animals↗

PubMed2003

Measurement of fractional anisotropy using diffusion tensor MRI in supratentorial astrocytic tumors.

In vivo, water diffusion displays directionality due to presence of complex microstructural barriers in tissue. The extent of directionality of water diffusion can be expressed as a fractional anisotropy (FA) value, using diffusion tensor MR imaging (DTI). The aim of this study was to determine whether FA values indicate microstructures in astrocytic tumors. We performed DTI in 31 patients with astrocytic tumor, and measured the FA values of tumor and normal brain regions prior to CT-guided stereotactic biopsy. After biopsy, FA values were compared to assess the cellularity and vascularity of tumor tissue. Although mean FA values trended to differ among histological types, all mean tumor FA values were lower than those of normal brain regions. Positive correlation was observed between FA values and both cellularity (r = 0.65, p < 0.05) and vascularity (r = 0.45, p < 0.05). We had hypothesized that the FA value of an astrocytic tumor would be determined by a balance between factors increasing the directionality of water diffusion, such as high cellularity and/or vascularity, and factors decreasing the directionality of water diffusion, such as fiber destruction. However, our results suggest that the FA values of glioblastoma, anaplastic astrocytoma, diffuse astrocytoma and pilocytic astrocytoma are largely affected by cellularity and/or vascularity, whereas that of gliomatosis cerebri are largely affected by the preservation of nerve fibers. Measurement of FA value using DTI will allow prediction of histological characteristics such as cellularity, vascularity and/or fiber structure in astrocytic tumors.

Adult↗

PubMed2003

Pulp cell responses during hypoxia and reoxygenation in vitro.

The purpose of this study was to investigate pulp cell responses during hypoxia and reoxygenation. Pulp tissues obtained from beagle dogs were cultured. In the control group, pulp cells were incubated in normoxic conditions (20% O2) for 1-4 d. In the hypoxia group, pulp cells were incubated under hypoxic conditions (2% O2) for 1-4 d. In the reoxygenation group, pulp cells were first incubated under hypoxic conditions for 24 h, and were then incubated in normoxic conditions (20% O2) for one to three additional days. Cell viability, MTT (3- (4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) reduction assay, cellular proliferation, and alkaline phosphatase (ALPase) activity were determined. Expression of heat shock protein 70 (HSP70) and vascular endothelial growth factor (VEGF) was analysed by Western blotting. Hypoxia inducible factor-1alpha (HIF-1alpha) in pulp cells was analysed by reverse transcriptase polymerase chain reaction (RT-PCR). The cell growth rate and ALPase activity were significantly higher in the hypoxia group than in the control group. After reoxygenation, cellular proliferation and ALPase activity decreased to the level of the control group while HSP70 expression increased. Hypoxia inducible factor-1alpha expression was detected in pulp cells, and VEGF expression (which is regulated by HIF-1alpha) increased under hypoxic conditions. These results suggest that dynamic responses to hypoxia and reoxygenation occur in pulp cells.

Alkaline Phosphatase↗

PubMed2003

Biological characteristics of the junctional epithelium.

This review summarizes the biological properties of the junctional epithelium, focusing on its developmental aspects, wide intercellular spaces and desmosomes, dense granules, permeability barrier, phagocytotic activity, adhesive structures and nerve terminals. It also discusses the morphology and functions of long junctional epithelium and peri-implant epithelium. Junctional epithelium is derived from the reduced enamel epithelium during tooth development. Apoptosis occurs in the border between oral and reduced enamel epithelia during tooth eruption. Junctional epithelium expresses a cytokeratin-19 immunoreaction, suggesting that this protein is a consistent differentiation marker. Wide intercellular spaces, which contain neutrophils and nerve endings, are formed as there are fewer desmosomes than in the oral epithelium. Dense, membrane-bound granules in the epithelium might correspond with membrane-coating granules, as revealed by their shape, components and freeze-fracture images. Junctional epithelium with high permeability contains exogenously expressed alpha-defensins, while stratified epithelia contain endogenously expressed beta-defensins. The phagocytotic activity in this epithelium remains unclear. Integrin-alpha6beta4 and laminin-5 form a complex in the tooth surface internal basal lamina. Long junctional epithelium created experimentally attaches to the cementum surface by hemidesmosomes and basal lamina. The peri-implant epithelium differs in proliferation and in adhesive structure from the normal junctional epithelium. In conclusion, wide intercellular spaces and poorly developed desmosomes are closely correlated with a permeable nature. There is still uncertainty over the phagocytotic activity of the epithelium. Integrin-alpha6beta4 and laminin-5 form a significant complex in the internal basal lamina. Junctional epithelium receives a rich sensory nerve and has a high rate of cell turnover. Long junctional epithelium can be produced rapidly during wound healing, due to high proliferative activity. Peri-implant epithelium might be a poorly adhered and permeable epithelium.

Animals↗

PubMed2003

Transcranial regional cerebral oxygen saturation monitoring during carotid endarterectomy as a predictor of postoperative hyperperfusion.

OBJECTIVE: Hyperperfusion syndrome is a rare but potentially devastating complication that can occur after carotid endarterectomy (CEA). The purpose of this study was to determine whether intraoperative transcranial regional cerebral oxygen saturation (rSO(2)) monitoring via near-infrared spectroscopy could be reliably used to identify patients at risk for post-CEA hyperperfusion. METHODS: rSO(2) was intraoperatively monitored for 50 patients undergoing CEA for treatment of ipsilateral internal carotid artery stenosis (>/=70%). Cerebral blood flow (CBF) was also assessed, with single-photon emission computed tomography, before and immediately after CEA. RESULTS: Post-CEA hyperperfusion (CBF increase of >/=100%, compared with preoperative values) was observed for six patients. A significant linear correlation was observed between the rSO(2) increases immediately after declamping of the internal carotid artery and the CBF increases immediately after CEA (r(2) = 0.247, P = 0.0002). The sensitivity and specificity of the rSO(2) increases for detection of post-CEA hyperperfusion were 100 and 86.4%, respectively, with a cutoff point of 5%. A strong linear correlation was observed between the rSO(2) increases at the end of the procedure and the CBF increases immediately after CEA (r(2) = 0.822, P < 0.0001). Both the sensitivity and the specificity of the rSO(2) increases for detection of post-CEA hyperperfusion were 100% with a cutoff point of 10%. Hyperperfusion syndrome developed for one patient with post-CEA hyperperfusion, but intracerebral hemorrhage did not occur. CONCLUSION: Intraoperative rSO(2) monitoring can reliably identify patients at risk for hyperperfusion after CEA.

Aged↗

PubMed2003

Diffusion tensor imaging in patients with major cerebral artery occlusive disease.

Diffusion tensor (DT) imaging provides quantitative information about the magnitude and the directionality (anisotropy) of water diffusion in vivo and can detect pathologic changes in brain ischemia. This study tried to detect ischemic brain damage using DT imaging in patients with symptomatic chronic major cerebral artery occlusive disease. DT imaging was performed using a 3.0 Tesla magnetic resonance (MR) scanner in 50 patients with unilateral internal carotid artery or middle cerebral artery stenosis or occlusion, who had no obvious infarct lesions on conventional MR imaging. Thirty-three patients underwent DT imaging before and after vascular reconstruction surgery. Fractional anisotropy (FA) was calculated in the middle cerebral artery territory. Preoperative FA values in the ipsilateral side were significantly lower than those in the contralateral side. After surgery, the FA value was significantly increased. DT imaging may indicate ischemic brain damage, not visualized by conventional MR imaging, in patients with major cerebral artery occlusive disease.

Adult↗

PubMed2003

An experimental study on the features of peri-implant epithelium: immunohistochemical and electron-microscopic observations.

The purpose of this study was to investigate the immunohistochemical and the ultrastructural features of the implant circumference epithelium of the beagle dog using various types of antibodies. The peri-implant epithelium was at an acute-angle from the gingival epithelium and was arranged in parallel to the implant surface. With immunohistochemical staining, the peri-implant epithelium was strongly positive for KL-1, and weakly positive for CK4, CK8 and CK19. These positive reactions for keratins and also for PCNA and BM-1 were similar to those seen in the oral mucosa. In the peri-implant epithelium, a plentitude of microvilli were observed at the periphery of cells at the implant sites, and bacteria were observed between the implant and the peri-implant epithelium without the formation of half desmosomes. There were many lipid-like vacuoles or lysosome-like granules. The intercellular space was wider than the junctional epithelium, and random migrations of large numbers of neutrophils could be seen. Taken together, the peri-implant epithelium is similar to that seen in the oral mucosa, and it is structurally different from the junctional epithelium.

Animals↗

PubMed2003

Papillary cystadenoma arising from the upper lip: a case report.

We report a rare case of a papillary cystadenoma arising from the upper lip. This tumor was not distinctly encapsulated and had proliferated replacing the ductal epithelium. Mast cells were found not only in the stroma but also in the oncocytic epithelial layer. There was a strong immunoreaction with mitochondrial antibody in the epithelial layer. Only one case (0.9%) of papillary cystadenoma has occurred among the 110 benign intraoral salivary gland tumors seen in our hospital from 1966 through September 2003.

Cystadenoma, Papillary↗

PubMed2003

Intravascular papillary endothelial hyperplasia arising from the upper lip.

We report a rare case of intravascular papillary endothelial hyperplasia (IPEH) arising from the upper lip. Pathologically, it consisted of a few lobulated masses lined by an incomplete fibrous capsule of variable thickness which was separated from the surrounding tissue and which partially formed papillary structures bearing fibrous stalks and a single layer of endothelium. The capillary formation was poorly defined, and mitotic figures were frequently observed. Immunohistochemically, the endothelial cells were positive for factor VIII related antigen and vimentin, and many cells were positive for PCNA, not only in the solid proliferating area but also in the papillary proliferating area. This case represents IPEH with high proliferative activity.

Adult↗

PubMed2003

A case of calcifying odontogenic cyst with numerous calcifications: immunohistochemical analysis.

The purpose of this study was to investigate a case of calcifying odontogenic cyst (COC) in which numerous calcifications were observed not only in the lining epithelium, but also in the cyst wall, using cytokeratins 13 (CK13), 19 (CK19), and core binding factor a-1 (cbfa-1) as primary antibodies. Cells of Malassez's epithelial rest were stained as controls. Cells of the epithelial nests in the cyst wall were reactive for CK13, but their CK19 staining was similar to that observed in the lining epithelial cells. Calcifying nodules were reactive only for CK13. Cells of Malassez's epithelial rest were reactive for CK19 but not for CK13. Cbfa-1 positive reactivity was observed only in nuclei of spindle cells in the periodontal ligament. CK13 was positive superficial to the prickle cells. CK19 was positive in the basal cells of the oral mucosa. In the lining epithelium of the cyst, the expressions of CK13 and CK19 were similar to their immunoreactions in the oral mucosa. These results suggest that the odontogenic epithelium differentiated into squamous epithelial cells, which began as ghost cells in the COC, and that this process depended on the dystrophic calcification of differentiated odontogenic epithelial cells, not of osteogenic cells.

Adult↗

PubMed2003

Prediction and monitoring of cerebral hyperperfusion after carotid endarterectomy by using single-photon emission computerized tomography scanning.

OBJECT: The purpose of this study was to determine whether the preoperative measurement of acetazolamide-induced changes in cerebral blood flow (CBF), which is performed using single-photon emission computerized tomography (SPECT) scanning, can be used to identify patients at risk for hyperperfusion following carotid endarterectomy (CEA). In addition, the authors investigated whether monitoring of CBF with SPECT scanning after CEA can be used to identify patients at risk for hyperperfusion syndrome. METHODS: Cerebral blood flow and cerebrovascular reactivity (CVR) to acetazolamide were measured before CEA in 51 patients with ipsilateral internal carotid artery stenosis (> or = 70% stenosis). Cerebral blood flow was also measured immediately after CEA and on the 3rd postoperative day. Hyperperfusion (an increase in CBF of > or = 100% compared with preoperative values) was observed immediately after CEA in eight of 12 patients with reduced preoperative CVR. Reduced preoperative CVR was the only significant independent predictor of post-CEA hyperperfusion. Forty-three patients in whom hyperperfusion was not detected immediately after CEA did not exhibit hyperperfusion on the 3rd postoperative day and did not experience hyperperfusion syndrome. In two of eight patients in whom hyperperfusion occurred immediately after CEA, CBF progressively increased and hyperperfusion syndrome developed, but intracerebral hemorrhage did not occur. In the remaining six of eight patients in whom hyperperfusion was detected immediately after CEA, the CBF progressively decreased and the hyperperfusion resolved by the 3rd postoperative day. CONCLUSIONS: Preoperative measurement of acetazolamide-induced changes in CBF, which is performed using SPECT scanning, can be used to identify patients at risk for hyperperfusion after CEA. In addition, post-CEA monitoring of CBF performed using SPECT scanning results in the timely and reliable identification of patients at risk for hyperperfusion syndrome.

Acetazolamide↗

PubMed2003

[A long-lasting idiopathic factor V inhibitor].

A rare case of a long-standing idiopathic acquired blood coagulation factor V (FV) inhibitor is reported. A 78 year-old male was admitted complaining of hematuria and tarry stools of two weeks' duration. He was noted to have a prolonged prothrombin time and activated partial thromboplastin time. A mixing study suggested the existence of an inhibitor and the activity of FV was less than 1%. Western blot analysis revealed the presence of anti-FV antibodies in the patient's serum. Because of significant bleeding tendencies, the patient received fresh-frozen plasma, platelet transfusions and methylprednisolone. His PT, APTT and FV activity were partially corrected although the disease was exacerbated when the steroid dose was tapered off. The patient was then treated with low dose cyclophosphamide. The majority of the cases with acquired FV inhibitor occur spontaneously in older patients but this condition may be associated with a surgical procedure, administration of antibiotics, tuberculosis or malignant diseases; some of them are, however, idiopathic. No underlying disease was detected in our present patient. The inhibitor disappears within 10 weeks in most patients and the prolonged presence of an idiopathic FV inhibitor is rare.

Aged↗

PubMed2003

Preoperative evaluation of neural tracts by use of three-dimensional anisotropy contrast imaging in a patient with brainstem cavernous angioma: technical case report.

OBJECTIVE AND IMPORTANCE: We describe a case of brainstem cavernous angioma in which the neural tracts were evaluated before surgery by three-dimensional anisotropy contrast (3-DAC) magnetic resonance imaging. CLINICAL PRESENTATION: A 64-year-old man presented with a cavernous angioma located intrinsically in the brainstem and manifesting as gait ataxia. 3-DAC imaging demonstrated that the lesion was located outside the left inferior cerebellar peduncle and inside the middle cerebellar peduncle. INTERVENTION: The intact brain surface was incised, and the lesion was removed successfully on the basis of the preoperative 3-DAC images. The patient exhibited temporary exacerbation of his gait ataxia, but the symptom improved 3 months after surgery. Postoperative 3-DAC imaging demonstrated resection of the lesion and preservation of the left inferior and middle cerebellar peduncles. CONCLUSION: 3-DAC imaging may provide essential information about the neural tracts for the planning of brainstem surgery.

Anisotropy↗

PubMed2002

Enhanced secretion of glucagon-like peptide 1 by biguanide compounds.

Metformin was reported to increase plasma active glucagon-like peptide-1 (GLP-1) in humans. There are two possible mechanisms for this effect: (1) metformin inhibits dipeptidyl peptidase IV (DPPIV), an enzyme degrading GLP-1, and (2) metformin enhances GLP-1 secretion. To elucidate the mechanism(s), we examined (1) IC(50) of metformin for DPPIV inhibition, (2) plasma active GLP-1 changes after oral biguanide (metformin, phenformin, and buformin) treatment in fasting DPPIV-deficient F344/DuCrj rats, and (3) plasma intact GLP-1 excursions after oral administration of metformin and/or valine-pyrrolidide, a DPPIV inhibitor, in fasting DPPIV-positive F344/Jcl rats. Our in vitro assay showed that metformin at up to 30mM has no inhibitory activity towards porcine or rat DPPIV. Metformin treatment (30, 100, and 300mg/kg) increased plasma active GLP-1 levels dose-dependently in DPPIV-deficient F344/DuCrj rats (approximately 1.6-fold at 3 and 5h after administration of 300mg/kg). This treatment had no effect on blood glucose levels. Similarly, phenformin and buformin (30 and 100mg/kg) elevated plasma intact GLP-1 levels in F344/DuCrj rats. In DPPIV-positive F344/Jcl rats, coadministration of metformin (300mg/kg) and valine-pyrrolidide (30mg/kg) resulted in elevation of plasma active GLP-1, but neither metformin nor valine-pyrrolidide treatment alone had any effect. These findings suggest that metformin has no direct inhibitory effect on DPPIV activity and that metformin and the other biguanides enhance GLP-1 secretion, without altering glucose metabolism. Combination therapy with metformin and a DPPIV inhibitor should be useful for the treatment of diabetes.

Animals↗