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Biomedical subjects

J Koyama

Publications and source records attributed to J Koyama.

At least 37 records · Page 2Linked to original sources
PubMed2001

The accuracy of sonography for evaluation of internal derangement of the temporomandibular joint in asymptomatic elementary school children: comparison with MR and CT.

BACKGROUND AND PURPOSE: In order to clarify the incidence and evolution of disk displacement in the temporomandibular joint (TMJ) in children, we performed a longitudinal analysis in 18 subjects. Some investigators have suggested that sonography can provide information about the articular disk position of the TMJ. The purpose of this study was to determine the diagnostic accuracy of sonography for revealing internal derangement of the TMJ in elementary school children compared with our standard of reference, MR imaging and helical CT. METHODS: Eighteen children were examined using both sonography and MR imaging or helical CT or both. The sonographically revealed distance between the articular capsule and the lateral surface of the mandibular condyle was measured and compared with that obtained by MR or helical CT scanning. RESULTS: Compared with our MR/CT standard of reference, sonography revealed a sensitivity of 83%, a specificity of 96%, and an accuracy of 92% for identifying disk displacement (defined as a distance of 4 mm or more between the articular capsule and the lateral surface of the mandibular condyle). CONCLUSION: Although sonography's sensitivity, specificity, and accuracy for the diagnosis of disk displacement were slightly inferior to those of MR or helical CT, we assert it is a useful imaging method for longitudinal investigations of a large group of elementary school children. Internal derangement of the TMJ should be suspected if sonography reveals a distance between the articular capsule and the lateral surface of the mandibular condyle of 4 mm or more.

Child↗
PubMed2001

[A giant thrombosed aneurysm of the anterior communicating artery which developed 18 years after clipping: a case report].

A 64-year-old man, who had undergone clipping surgery 18 years before for a ruptured anterior communicating artery (ACoA) aneurysm, presented with mild aphasia. A computerized tomography (CT) scan showed a subcortical hemorrhage in the left temporal lobe, and a high density large mass at the ACoA. Neuro-imaging study revealed a giant thrombosed ACoA aneurysm. Thrombectomy and neck clipping were successfully performed, using the interhemispheric approach. The patient was discharged without additional neurological deficits. A long-term follow-up study is thus considered necessary after neck clipping of a ruptured aneurysm.

Humans↗
PubMed2000

Relation between vascular morphologic changes during stent implantation and the magnitude of in-stent neointimal hyperplasia.

Intimal hyperplasia usually occurs after balloon overstretch injury or wire coil stimuli to coronary arteries. We examined whether the degree of vessel wall stretch during coronary stent placement could predict the amount of in-stent neointimal hyperplasia after a 6-month follow-up. Serial (preintervention, postballooning, poststent implantation, and a follow-up after 6 months) intravascular ultrasound (IVUS) was used to study 457 consecutive cross-sectional areas in 28 patients. IVUS imaging, using a motorized pullback system at 0.5 mm/s, allowed 1-mm axial increment measurements of the total vascular, stent, and lumen cross-sectional areas. The mean total vascular area changed from 10.89 +/- 2.50 mm2 before to 11.27 +/- 2.49 mm2 after ballooning, to 12.80 +/- 2.59 mm2 after stenting, and to 12.58 +/- 2.41 mm2 at follow-up (p < 0.0001). The mean lumen area changed from 3.36 +/- 1.95 mm2 before to 4.21 +/- 1.65 mm2 after ballooning, to 5.16 +/- 1.09 mm2 after stenting, and to 3.57 +/- 1.23 mm2 at follow-up (p < 0.0001). The mean stent area decreased from 5.25 +/- 1.17 mm2 after stenting to 5.09 +/- 0.90 mm2 at follow-up (p < 0.0001). Stepwise logistic regression analysis showed that delta total vascular area (after stent implantation - before intervention) was a strong predictor of the amount of intimal hyperplasia (r = 0.57, p < 0.0001). Vascular overstretch caused by the stenting procedure promotes intimal hyperplasia in proportion to the degree of sectional vascular stretch.

Aged↗
PubMed2000

Cardiac amyloid in patients with familial amyloid polyneuropathy consists of abundant wild-type transthyretin.

Patients with familial amyloid polyneuropathy (FAP) are now cured by liver transplantation, but cardiac amyloidosis would further progress even after liver transplantation in some patients. To clarify the pathological mechanism of the progress of cardiac amyloidosis in FAP, we investigated cardiac tissues obtained from 6 FAP patients with 3 different types of TTR mutations. One of them had undergone liver transplantation and one year later died of cardiac amyloidosis. We determined clinical severity of cardiac involvement of those patients and characterized amyloid fibril proteins depositing in their cardiac muscles by immunohistochemistry, mass spectrometry and isoelectric focusing. All the patients had cardiac dysfunction and increased cardiac weight. Diffuse deposition of TTR-related amyloid was seen in their myocardium on microscopic examination. Amyloid fibrils of the heart were composed of wild-type TTR as well as variant TTR at a ratio of about 1:1 in 5 patients without liver transplantation. In the patient with a transplanted liver, about 80% of the cardiac amyloid consisted of wild-type TTR. Wild-type TTR contributes greatly to the development of amyloid deposition in the heart of FAP patients regardless of the types of TTR mutations.

Adult↗
PubMed2000

Cyclopentene dialdehydes from Tabebuia impetiginosa.

The isolation of two cyclopentene dialdehydes, 2-formyl-5-(4'-methoxybenzoyloxy)-3-methyl-2-cyclopentene-1-acetal dehyde, and 2-formyl-5-(3', 4'-dimethoxybenzoyloxy)-3-methyl-2-cyclopentene-1-acetaldehyde, from the bark of Tabebuia impetiginosa is reported. The structures were established by analysis of spectroscopic data. These compounds showed anti-inflammatory activity.

Aldehydes↗
PubMed2000

Influence of N-terminal peptide and oligosaccharide on the clearance of t-PA.

We have studied the influence of Gly-Ala-Arg peptide at the N-terminus and the oligosaccharide at Asn184 on the clearance of tissue plasminogen activator (t-PA). In order to intensify the influence of these structural features, Gln117 t-PA, which is a mutant tissue plasminogen activator (mt-PA) expressed in mouse C127 cells, was used for the investigation. It is altered to remove a high mannose type oligosaccharide by the mutation of an amino acid from Asn117 to Gln. We isolated 4 variants of Gln117 t-PA by cation-exchange chromatography, which are abbreviated as S-I, S-II, L-I and L-II. These variants originated from the heterogeneity of the peptide chains (S-chain, 527 amino acids, L-chain, 530 amino acids) and oligosaccharide (Type I, 2 oligosaccharides, Type II, 1 oligosaccharide). Pharmacokinetics of these variants were investigated after single intravenous administration to male rats at a dose of 250 microg/kg. Significant differences in pharmacokinetic parameters were observed among these variants, but there was no considerable difference in fibrin clot lysis time (FCLT) activity. Gly-Ala-Arg peptide at the N-terminus increased the CLt, whereas the oligosaccharide at Asn184 decreased the CLt. Moreover, the effects of the N-terminal peptide and the oligosaccharide on the CLt were independent of each other. Our study with Gln117 t-PA revealed the role of the N-terminal peptide found in the L-chain produced during the processing of t-PA precursor.

Animals↗
PubMed2000

Enantiomeric separation by cyclodextrin modified capillary zone electrophoresis (CD-CZE) of quaternary tetrahydroprotoberberine alkaloids.

A cyclodextrin modified capillary zone electrophoresis (CD-CZE) for the enantiomeric separation of tetrahydroprotoberberine N-metho salts was established. The resolution was optimized by changing the concentration of the electrolyte solution, hydroxypropyl-beta-CD (0.02 M, 0.07 M, or 0.14 M) or dimethyl-beta-CD (0.05 M or 0.15 M) in phosphate buffer (pH 2.5 or 3) containing 10% acetonitrile with an applied voltage of 20 kV. This method was applied toward the enantioselective bio-conversion of quaternary tetrahydroprotoberberine N-metho salts in cultured cells of Corydalis species.

Berberine↗
PubMed2000

Micellar electrokinetic chromatography (MEKC) separation of furanonaphthoquinones from Tabebuia impetiginosa.

The separation of nine furanonaphthoquinones by micellar electrokinetic chromatography (MEKC) is described. The running electrolytes used in this method were 0.03 M sodium dodecyl sulphate (SDS) in 0.09 M borate buffer (pH 9) containing 10% methanol, with an applied voltage of 20 kV. Application of this technique in the determination of the main furanonaphthoquinones, 5-hydroxy-2-(1-hydroxyethyl)naphtho[2,3-b]furan-4,9-dione, 8-hydroxy-2-(1-hydroxyethyl)naphtho[2,3-b]furan-4,9-dione, and 2-(1-hydroxyethyl)naphtho[2,3-b]furan-4,9-dione, of Tabebuia impetiginosa is demonstrated in this paper.

Chromatography, Micellar Electrokinetic Capillary↗
PubMed2000

Primary cardiac malignant fibrous histiocytoma in the right ventricular infundibulum treated with a cavo-pulmonary shunt and coronary embolization.

A 51-year-old woman presented with progressive right ventricular infundibular wall thickening and outflow obstruction. She had had an aorto-coronary bypass for left main coronary artery disease 1 year after radiation therapy for left mammary cancer. Enhanced computed tomography showed a mass in the right ventricular free wall with no connection to the mediastinum; the tumor extended into the main pulmonary artery, but there was no other evidence of a primary or metastatic tumor. A biopsy specimen was obtained and based on the microscopic and immuno-histochemical findings (vimentin and Kp-1 positive) the diagnosis was primary cardiac malignant fibrous histiocytoma, which is very rare. A cavo-pulmonary artery connection lessened her symptoms, but embolization of the coronary artery to try and to reduce the mass had minimal effect. Four months after the tumor was diagnosed she died of extended pulmonary artery obstruction.

Arterial Occlusive Diseases↗
PubMed2000

A newly designed key-hole button.

Patients who have undergone frontotemporal craniotomy occasionally complain of scalp deformity in the anterior temporal area. This occurs as a result of inappropriate reconstruction of the temporal muscle and repair of the bone defect at the key hole and surrounding skull. Although several methods have been developed to prevent skin indentation on burr holes located over the convexity, satisfactory cosmetic repair of the key hole remains difficult because of its complicated bone curvature. To prevent such postoperative deformity, the authors designed a button made of hydroxyapatite ceramics to fit the key hole easily. This new, biocompatible "key-hole button" is shaped to alleviate the deformity of the temple by filling the bone defect in a more natural way. The specifications of this device and its clinical application are described.

Biocompatible Materials↗
PubMed2000

Induced apoptosis and necrosis by 2-methylfuranonaphthoquinone in human cervical cancer HeLa cells.

2-Methylnaphtho[2,3-b]furan-4,9-dione (FNQ3) has been reported to be more cytotoxic to human malignant tumor cell lines than are the corresponding normal epithelial cells. Therefore, we examined the dose response of FNQ3 against human cervical cancer HeLa cells in culture. When 1.25 mg/ml FNQ3 was applied, apoptosis was induced, as determined by an immunohistochemical staining of fragmented genome DNA and cell profiles. Significant inhibition of Bcl-2 oncogene protein expression by the same concentration of FNQ3 also was demonstrated by an immunohistochemical staining method to visualize the expressed cells and Western blot in polyacrylamide gel electrophoresis. Flow-cytometric spectra showed S-phase arrest in cell cycles and the appearance of sub-G1 phase consistent with apoptosis. On the other hand, concentrations of 5 microg/ml or more of FNQ3 induced necrosis. These results show that FNQ3 may act as an antitumor agent to induce apoptosis by affecting Bcl-2 expression and cell cycles, or necrosis as the result of primary mitochondrial injuries.

Antineoplastic Agents, Phytogenic↗
PubMed2000

[Surgical treatments for 7 pituitary adenomas in multiple endocrine neoplasia type 1].

We analyzed 7 pituitary adenomas in patients with multiple endocrine neoplasia type 1 (MEN1). Their incidence was 1.6% among 450 patients with pituitary adenomas which had been treated surgically in our department between 1978 and 1999. The age, gender, symptoms, type of hormone secretion, pathological and operative findings in the MEN1 patients were not apparently different from those in the non-MEN1 patients. Incidence of non-functioning pituitary adenomas, however, was more frequently encountered in our series than that in previous reports among Caucasian people. One patient who had 5 previous operations for the MEN tumors died following postoperative subarachnoid hemorrhage. Four of the seven patients presented initial symptoms related to pituitary adenomas and increased serum Ca level was retrospectively recognized in three of the four at the time of treatment for the pituitary adenomas.

Adenoma↗
PubMed1999

Effect of distal stenosis of internal thoracic artery bypass grafts on longitudinal phasic blood flow velocity characteristics.

BACKGROUND: Left internal thoracic artery (LITA) bypass conduits show gradual longitudinal transition in their phasic flow velocity patterns from the proximal to distal segments, but little is known about the influence of distal stenosis, particularly early after surgery, on that characteristic. The purpose of this study was to evaluate the influence of distal stenosis on these flow velocity patterns. METHODS: We examined 24 LITAs within 1 month (7 to 30 days) after surgery with a Doppler-tipped guide wire at the proximal, mid, and distal segments. Maximum peak velocities (MPV), time averaged peak velocities (APV), and velocity-time integrals (VTI) were measured. RESULTS: In LITAs without stenosis (n = 14, group A), the APV, MPV, and VTI values at the diastole were significantly greater than those for distal stenosis (minimal lumen diameter >75%, n = 10, group B). The values of the 3 indexes at the systole in each segment did not differ significantly between the 2 groups. Both groups showed gradual increases in the diastolic/systolic ratios of the 3 indexes from the proximal to distal portions, the ratios in group A being significantly larger than that in group B (APV, P <. 001; MPV, P <.01; TVI, P <.01, respectively). For these indexes, sensitivity and specificity for predicting stenosis of LITA was higher in the proximal and mid portion than in the distal. CONCLUSIONS: Anastomotic stenosis decreases the diastolic flow component but not the systolic one. By using diastolic/systolic ratios of the 3 indexes, it is possible to predict distal stenosis of LITA from the resting phasic flow velocity pattern.

Aged↗
PubMed1999

Detectability of anterior displacement of the articular disk in the temporomandibular joint on helical computed tomography: the value of open mouth position.

OBJECTIVE: The purpose of this study was to establish the diagnostic reliability of anterior displacement of the articular disk in the temporomandibular joint on helical computed tomography. STUDY DESIGN: Ninety-four consecutive patients were examined through use of both computed tomography and magnetic resonance imaging. On axial computed tomography, anterior disk displacement was defined as the presence of an area of soft tissue density that was semilunar in shape and located in front of the mandibular condyle. RESULTS: With magnetic resonance imaging taken as the diagnostic gold standard in evaluation of articular disk position, the sensitivity, specificity, and accuracy for computed tomography were 91%, 100%, and 97%, respectively, in the closed mouth position and 96%, 99%, and 98%, respectively, in the open mouth position. CONCLUSIONS: The detectability on axial helical computed tomography of anterior displacement of the articular disk in the temporomandibular joint in the open mouth position was almost equal to that on magnetic resonance imaging. It is recommended that the open mouth position be added when helical computed tomography is used to evaluate patients with temporomandibular joint disease.

Absorptiometry, Photon↗
PubMed1999

Furanonaphthoquinone analogs possessing preferential antitumor activity compared to normal cells.

The 50% growth inhibition toxicity (IC50 at 72 h) of 16 synthetic and 2 phytochemical natural analogs of furanonaphthoquinones (naphtho[2,3-b]furan-4,9-dione; FNQ) and 2 analogs of isofuranonaphthoquinones was assayed in vitro in respect to established human cervical cancer and lung adenocarcinoma cells in comparison with human uterine endocervical, tracheal and bronchiolar epithelial cells and fibroblasts. Prostate, cholangio, colon, laryngeal, and tongue carcinoma cell lines and two osteosarcoma cell lines were also used for the assay. The IC50 ratio of normal cells to cancer cells was estimated in order to represent preferential antitumor activity. Two analogs, 2-methylnaphtho[2,3-b]furan-4, 9-dione (FNQ3) and 2-methyl-5(or 8)-hydroxynaphtho[2,3-b]furan-4, 9-dione (FNQ13) showed 10.4 to 14.1 IC50 ratios for all carcinoma cells used, indicating a wide spectrum. Among different carcinomas, there was no difference or variety in the IC50 ratio of a single analog. A moderate IC50 ratio (3.1-4.7) was also found in nine analogs, but seven others were equally cytotoxic (less than 2.6) to both cancer and normal cells. Two isofuranonaphthoquinone derivatives were ineffective, but a thieno derivative was equally cytotoxic to all cells tested. On the basis of the IC50 ratio data and the structure of the furanonaphthoquinones, the following structural activity (selectivity) relationship can be postulated: (i) the presence of an alkyl group at position 2 enhances the IC50 ratio, particularly the methyl group; (ii) a hydroxyl group at position 5 or 8 enhances the IC50 ratio; and (iii) methylation of the phenolic hydroxyl group leads to a decrease of potency. These results indicate that FNQ3, 13, and some other analogs are more preferentially cytotoxic to human tumor cells than to normal cells, unlike mitomycin-C, adriamycin, carboplatin, and methotrexate which are cytotoxic to the both. In nude mouse xenograft tests, FNQ3 demonstrated a significant antitumor activity with T/C% values of 16. 6 to 41.6 against several human carcinoma and osteosarcoma cells.

Animals↗
PubMed1999

Structural injury of osteosarcoma mitochondria by a novel antitumour agent, 2-methylfuranonaphthoquinone.

The effect of the novel anticancer 2-methylnaphtho[2,3-b]furan-4,9-dione (FNQ3) on human osteosarcoma cell lines (HuO9 and HuO9N2) was investigated. The IC50 values of FNQ3 were 5.95 microM for HuO9 and 3.86 microM for HuO9N2, while that for normal fibroblasts (WI-38 cell line) was 35.8 microM. The selectivity in antitumour activity which was estimated from the IC50 ratio of normal fibroblasts to tumour cells was 6.0 and 9.3 fold for HuO9 and HuO9N2, respectively. FNQ3 at 23.6 microM selectively injured mitochondria of HuO9 cells starting at 36 h and HuO9N2 cells at 24 h, whereas WI-38 cells were unaffected even after 72 h. These results demonstrated that FNQ3 was selectively toxic to the mitochondria of osteosarcoma cells similar to carcinoma cells (Pan et al. (1997) J. Electron Microsc. 46: 181), in comparison to normal cells.

Antineoplastic Agents, Phytogenic↗
PubMed1999

Condylar bony change and craniofacial morphology in orthodontic patients with temporomandibular disorders (TMD) symptoms: a pilot study using helical computed tomography and magnetic resonance imaging.

OBJECTIVE: To investigate how condylar bony changes relate to craniofacial morphology using helical CT and MRI. DESIGN: Craniofacial morphology of orthodontic patients with condylar bony changes was compared with Japanese standard. SETTING AND SAMPLE POPULATION: The Department of Orthodontics, Niigata University School of Dentistry, Twenty-nine subjects were selected from orthodontic patients (six males and 23 females, a mean age of 18.8 +/- 6.3 years) who were diagnosed by helical CT as having condylar bony changes. EXPERIMENTAL VARIABLE: Subjects were divided into two groups: a unilateral condylar bony change group (unilateral group) (four males and nine females) and a bilateral condylar bony change group (bilateral group) (two males and 14 females). OUTCOME MEASURE: Condylar bony changes were evaluated on reconstructed coronal and sagittal CT scans. Disk positions were evaluated by MRI scans. Five linear and four angular measurements in lateral and posteroanterior cephalograms were compared with those of an age- and sex-matched 'standard population' from the Japanese standard. RESULTS: In the bilateral group, osteophyte formation and erosion were the common bony changes and were present in adult as well as juvenile subjects. In the unilateral group, flattening was the most common features and erosion was only present in subjects below 19 years. Disk displacement without reduction was seen in 90.6% of the bilateral group, and in 76.9% of the unilateral group. Retrognathic mandibles were shown in the bilateral group. All subjects exhibited a lateral shift of the menton toward the condylar bony changed side in the unilateral group. CONCLUSION: Condylar bony changes might be progressive and unstable in adults of the bilateral group as well as in juveniles of the both groups. It appears that condylar bony changes may be related to a lateral shift of the mandible and a retrognathic mandible in orthodontic patients with TMD symptoms.

Adolescent↗