Biomedical subjects

T Hamada

Publications and source records attributed to T Hamada.

At least 163 records · Page 9Linked to original sources

PubMed1999

Mechanism of inhibition of the Na current by tocainide in guinea-pig isolated ventricular cells.

Tocainide blocked the Na current (I(Na)) in ventricular myocytes in either a tonic or a phasic block manner, having a higher affinity for the inactivated state (K(di) = 18 microM) than for the rested state (Kd(rest) = 606 microM). The degree of phasic block was enhanced and the onset of phasic block was faster with an increase in pulse duration as well as at less-negative holding potential (HP). The recovery-time constant from the phasic block of I(Na) induced by tocainide was independent of either the HP or the removal of fast inactivation. After removal of fast inactivation, tocainide showed the pulse-duration dependency of phasic block but not the voltage dependency. These results suggest that tocainide could bind to the inactivated-state receptor through the hydrophilic pathway and leave the receptor through the hydrophobic pathway, producing the tonic and phasic block of I(Na).

Animals↗

PubMed1999

Occlusal force distribution on the dental arch during various levels of clenching.

The purpose of this study was to explore the occlusal force distribution on the dental arch in the intercuspal position and to evaluate the relationship between the clenching strength and the occlusal force distribution. These variables were recorded using the Dental Prescale System in 16 healthy young adults. The number of tooth contacts, occlusal force and occlusal contact area increased linearly as clenching strength increased. The distribution of the occlusal force was greatest at the molar region followed by the premolar and anterior teeth region. The proportion of occlusal force (occlusal force at each region/total occlusal force) on molar regions increased as clenching strength increased. On the contrary, the proportion of occlusal force on the premolar and anterior teeth regions decreased as clenching strength increased. These findings suggest that control of occlusal force is important in diagnosis of the nature of occlusal contacts.

Adult↗

PubMed1999

Incidence of occlusal contacts with complete dentures during mastication using a 6-channel telemetry system: preliminary measurements.

The purpose of this study was to observe the incidence of occlusal contact with complete dentures during mastication using a 6-channel telemetry system whose accuracy had been improved. The telemetry system consisted of the transmitter unit and the receiver unit. The transmitter unit was embedded in the lower complete denture. This system detects occlusal contacts by the shift of frequency in 100 kHz. The transmitter allowed 6 channels for the occlusal contacts. The data was telemetered by a time division multiplex communication method. A special switch was designed to measure excursive movement on the occlusal surface. After careful occlusal adjustment, the special switches were inserted in the lower first molars. On the basis of preliminary measurements on a 64-year-old edentulous male, it appears that the width of the gliding on the occlusal surface at the lower first molar was mostly 0.2-1.2 mm and the majority of the excursive movements ended at the centric occlusal position.

Dental Occlusion↗

PubMed1999

Effects of modified pellicles on Candida biofilm formation on acrylic surfaces.

The role of saliva or serum proteins, such as mucin, fibronectin (FN) and mannan-binding protein, on Candida biofilm formation was investigated. Supplementation of saliva with FN had no significant effect on biofilm formation. In contrast, biofilm formation on either mucin-coated or FN-coated acrylic surfaces was significantly less than that of the control. These results suggest that salivary mucin or FN alone does not facilitate biofilm formation of Candida. Supplementation of serum with FN increased biofilm formation of C. glabrata compared with the control. Pretreatment of serum with anti-FN monoclonal antibody significantly reduced biofilm formation, as did pretreatment of serum with anti-mannan-binding protein monoclonal antibody or Con-A. Therefore, Candida biofilm formation on acrylic surfaces appears to be a complex phenomenon involving a multiplicity of proteins operating intraorally.

Acrylates↗

PubMed1999

Distribution of cadmium and metallothionein in CdCl2-exposed rat kidney: relationship with apoptosis and regeneration.

Male Sprague-Dawley rats were injected subcutaneously with 0.6 mg cadmium/kg bodyweight per day for 6 weeks. In each week of exposure, rats were killed and the localization of cadmium and metallothionein in the kidney was studied by histochemical and immunohistochemical methods. Although cadmium was localized throughout the proximal tubules during exposure, apoptosis and subsequent regeneration were observed mainly in the straight portion of the proximal tubules after 4 weeks of exposure. The distribution of tubular injury may thus not necessarily coincide with that of cadmium. Expression of metallothionein was also detected in the cytoplasm and nuclei of the convoluted and the straight portion of the proximal tubules, but the latter became positive in accordance with apoptosis and regeneration. These results suggest a close relationship between metallothionein distribution and tubular cell regeneration.

Animals↗

PubMed1999

Myoepithelioma of soft tissue.

A myoepithelioma occurred in the subcutaneous tissue of the right shoulder of a 28-year-old man. The well-demarcated nodular tumor (3. 0 x 2.8 cm) was located in the subcutaneous tissue with no adhesion to the deltoid muscle. The tumor was composed of a fascicular proliferation of spindle cells with variable amounts of stroma and showed areas of sheets of epithelioid cells. In most areas, the tumor cells had uniform nuclei, but pleomorphic epithelioid cells were focally present. Mitotic activity was three per 10 high-power fields. No ductular structure was found throughout the tumor. Immunohistochemical and ultrastructural studies confirmed the myoepithelial origin of the tumor cells. The occurrence of myoepithelioma in the subcutaneous tissue has been rarely reported. Even though the tumor showed no aggressive behavior on the 2-year follow-up, it is still too early to comment definitely on the behav- ior of myoepithelioma of the subcutaneous tissue. This case provides further information about soft tissue myoepithelioma.

Adult↗

PubMed1999

A case of anaplastic large cell (Ki-1) lymphoma of B-cell phenotype, occurring in Waldenström's macroglobulinemia.

A case of anaplastic large cell (Ki-1) lymphoma of B-cell lineage occurred in a 59-year-old male with Waldenström's macroglobulinemia. Immunostaining of the lymphoma cells showed sporadic positivity for IgM and occasional positivity for kappa chain. This immunoglobulin specificity is the same as that of plasmacytoid lymphocytes in the bone marrow; therefore anaplastic transformation of Waldenström's macroglobulinemia was strongly suggested. This seems to be the first reported case of anaplastic large cell lymphoma, confirmed by CD30 expression, arising in Waldenström's macroglobulinemia.

Antigens, CD20↗

PubMed1999

Effects of amlodipine on native cardiac Na+ channels and cloned alpha-subunits of cardiac Na+ channels.

The inhibitory effects of amlodipine besilate (CAS 11470-99-6) on the native Na+ current (INa) and cloned human cardiac Na+ channel alpha subunit (hH1) were studied by whole cell patch clamp techniques. Amlodipine produced tonic block of INa in a concentration- and holding potential (HP)-dependent manner with hyperpolarization of H infinity. Amlodipine produced phasic blockade of INa, which was dependent on HP and pulse duration. Amlodipine produced tonic blockade of hH1 in a concentration-dependent manner with 1 : 1 stoichiometry, and phasic blockade of hH1 which was dependent on the pulse duration. Amlodipine blocked INa in a voltage- and frequency-dependent manner via affinity to the resting as well as inactivated conformations of the alpha subunit.

Algorithms↗

PubMed1999

Treatment of xerostomia with the bile secretion-stimulating drug anethole trithione: a clinical trial.

BACKGROUND: Saliva protects the oral mucosa, inhibiting microbial overgrowth. Hyposalivation, therefore, induces multiple oral disorders, although treatment of hyposalivation is very difficult. METHODS: A cholagogue, anethole trithione (AT) was administered to patients with symptomatic hyposalivation (xerostomia) caused by senile hypofunction (4 men and 17 women; senile group), medications (6 men and 17 women; drug group), and oral cancer therapy (two men and three women; cancer group). For control groups, an artificial saliva was administered to 45 patients consisting of senile hypofunction (10 men and 16 women), drug-induced xerostomia (3 men and 10 women) and oral cancer therapy-induced xerostomia (four men and two women). RESULTS: Two weeks after administration of AT (6 tablets per day), both nonstimulated salivary flow rate (SFR) and stimulated SFR increased in a statistically significantly manner from 0.76 +/- 0.41 and 5.18 +/- 3.02 to 1.54 +/- 1.33 (P<0.05) and 9.07 +/- 4.10 mL/10 min (P<0.05), respectively. Of the three groups, the drug group showed the largest increases in both SFRs, from 0.90 +/- 0.54 and 6.29 +/- 4.12 to 1.69 +/- 1.65 and 12.09 +/- 5.10 mL/10 min (P<0.05 and P<0.02, respectively). Patients in the control group had almost constant SFRs. After AT administration, the salivary viscosity was, however, mildly decreased and concentrations of secretory-immunoglobulin A, lactoferrin, potassium, and chloride in nonstimulated saliva were almost constant. Corresponding with the increase of salivation, oral discomfort and inflammation were improved or resolved in 41 patients of the AT group within about 4 weeks, whereas improvement was observed in only nine patients of the control group. CONCLUSIONS: These results indicate that AT sufficiently stimulates salivation and improves xerostomia.

Adult↗

PubMed1999

Phosphorylation of proteins in the stem section of etiolated rice seedling irradiated with red light.

The molecular mechanism of light signal perception was analyzed using stem sections of etiolated rice (Oryza sativa L.) seedlings irradiated with red light from a fluorescent lamp. The membrane and cytosol fractions were labeled by 40 nM [gamma-32P]ATP for 10 s at 0 degrees C and proteins were separated by two-dimensional polyacrylamide gel electrophoresis. Phosphorylation of three proteins with molecular weights of 16, 17 and 18 kDa in the rice increased with the intensity of red light irradiation (50 micromol/m2/s) for 16 min. Most of the phosphorylation activity was present in the cytosol fraction. The three proteins cross-reacted with the anti-nucleoside diphosphate (NDP) kinase antibody. Phosphorylation of these proteins was correlated with changes in the activity of NDP kinase. These proteins phosphorylated histone III-S, a substrate for measuring the protein kinase activity. By phospho-amino acid analysis, phosphoserine was found present in the phosphorylated proteins. These rapidly phosphorylated proteins would thus appear to have the features of NDP kinase.

Amino Acid Sequence↗

PubMed1999

Synthesis of 2-phenylbenzofuran derivatives as testosterone 5 alpha-reductase inhibitor.

A series of 2-phenylbenzofuran derivatives with a carbamoyl, alkylamino, or alkyloxy group at the 5 or 6 position of the benzofuran ring were synthesized and evaluated for rat and human testosterone 5 alpha-reductase inhibitory activities in vitro. Against rat enzyme, the carbamoyl derivatives had more potent inhibitory activities than the alkylamino or alkyloxy derivatives, and the 6-carbamoyl derivatives tended to be more potent than the 5-carbamoyl derivatives. Against human enzyme, the 6-substituted derivatives had more potent inhibitory activities than the 5-substituted derivatives. The 6-carbamoyl and 6-alkylamino derivatives tended to show stronger inhibitory activities against human type 1 enzyme than against type 2 enzyme, but they were not largely selective.

3-Oxo-5-alpha-Steroid 4-Dehydrogenase↗

PubMed1999

Determinants of exercise-induced ST-segment displacement in the aVL lead in patients with known or suspected coronary artery disease.

Although the aVL lead in exercise electrocardiography is reported to be helpful in identifying a significant narrowing of the left anterior descending coronary artery (LAD), its role in exercise testing has not been fully evaluated. Accordingly, 821 patients who underwent both standard exercise testing and coronary angiography were evaluated. In patients with aVL lead ST elevation, the incidence of a significant narrowing of the LAD (124/165 vs 348/656; p<0.001) was higher than in those without. Multiple logistic regression analysis revealed that the 2 most important variables that correlated with aVL lead ST elevation were a greater number of leads with ST depression in the inferior leads and a smaller amplitude of R wave in the aVL lead. In contrast, variables correlating with aVL lead ST depression in the majority of cases were a greater number of leads with ST depression in all leads and the presence of inferior lead ST elevation. The results of this study indicate that although aVL lead ST elevation could be a marker for LAD narrowing, more important factors such as inferior lead ST-segment depression and the R-wave amplitude of the aVL lead should be taken into consideration. In contrast, ST depression in the aVL lead mostly represents exercise-induced myocardial ischemia of greater extent and severity.

Adult↗

PubMed1999

Functional recovery after coronary artery bypass grafting in patients with severe left ventricular dysfunction and preserved myocardial viability in the left anterior descending arterial territory as assessed by thallium-201 myocardial perfusion imaging.

To evaluate the functional recovery after coronary bypass surgery in patients with severe left ventricular (LV) dysfunction (ejection fraction (EF) < or = 35%), 100 consecutive patients with viable myocardium in the territory supplied by the left anterior descending artery (LAD) underwent coronary bypass grafting. In addition, cardiac catheterization and single-photon emission computed tomography (SPECT) perfusion imaging with thallium-201 were repeated 1-year postoperatively. Although 12 patients with severe LV dysfunction were preoperatively in a worse New York Heart Association functional class (3.1+/-0.7 vs 2.4+/-0.8; p<0.01), had a higher incidence of heart failure (10/12 vs 14/88; p<0.001) and had a worse LVEF (29+/-5 vs 61+/-14%; p<0.001) compared with 88 patients without severe LV dysfunction, the operative mortality was similar in the 2 groups (1/12 vs 2/88; p=NS). The postoperative NYHA functional class in the patients with severe LV dysfunction was similar to that in the patients without such dysfunction (1.6+/-0.7 vs 1.3+/-0.6; p=NS). In addition, the 1-year postoperative study revealed a significant improvement in the thallium defect score in both the LAD territory (1.7+/-1.2 to 0.7+/-1.0, p=0.01) and all the territories (5.2+/-2.2 to 3.2+/-1.9, p=0.002) in patients with severe LV dysfunction, whereas no improvement in defect score was found in either of these territories in those without severe LV dysfunction (LAD: 0.6+/-1.4 to 0.4+/-1.2, p=NS; All: 1.9+/-2.2 to 1.8+/-2.0, p=NS). Furthermore, a marked 1-year postoperative improvement (15-24%; 95% confidence interval) in LVEF (29+/-5 to 48+/-10%, p<0.001) was demonstrated in patients with severe LV dysfunction, but not in those without such dysfunction (60+/-13 to 61+/-11%, p=NS). These results indicate that myocardial viability in the LAD territory, as demonstrated by thallium-201 SPECT perfusion imaging, predicts a significant improvement in functional class and LVEF of at least 10% or more after coronary artery bypass grafting in patients with severe LV dysfunction.

Adult↗

PubMed1999

Modulation of fas-mediated apoptosis in osteosarcoma cell lines.

Fas/APO-1 (or CD95) is a 45-kDa cell surface glycoprotein that transduces cellular death signals for apoptosis upon cross-linking with the Fas ligand, which is experimentally replaced by anti-Fas antibodies. We examined the Fas expression at the protein and mRNA levels, and susceptibility to anti-Fas-mediated apoptosis, in 14 osteosarcoma cell lines. Ten of 14 ostesarcoma cell lines constitutively expressed detectable levels of Fas on the cell surface with positive cell rates ranging from 10.2 to 72.4%. Four other cell lines expressed Fas almost exclusively in the cytoplasm. An antibody against Fas was able to induce Fas-mediated cell death only in two cell lines with high levels of surface Fas. In the presence of the protein synthesis inhibitor cyclohexamide, antibody to Fas led to an induction of apoptosis in ten of the osteosarcoma cell lines antibody-concentration dependently. These data suggest that Fas is a potential protein related to apoptosis in osteosarcomas when the sensitizing activity of cyclohexamide on anti-Fas-mediated cytotoxicity was exerted.

Antibodies, Monoclonal↗

PubMed1999

[The effect of 5-HT 2 antagonist for urinary frequency symptom on diabetes mellitus patients].

17 cases of patients with diabetes mellitus who had urinary frequency symptom for which anti-cholinergic agents proved ineffective were given Sarpogrelate Hydrochloride (Anplag), a selective 5-HT 2 receptor antagonist. Efficacy was judged using IPSS and QOL scores after 2 weeks medications, these showed that all cases had improved their urinary frequency during the days as well as the night. This was especially true for the QOL score. One time urinary volume markedly increased, but there was no statistical significance after medication in maximum flow rate and residual urine. At the same time, a separate group of 14 mainly BPH cases did not improve entirely. It is believed that reaction in the detrusor muscle with hyperreflexia of diabetes mellitus patients can reach 5-HT, and its reaction is believed to reach via the 5-HT 2 receptor. This paper is a first clinical report of making use of 5-HT 2 antagonist as hyperactive detrusor on diabetes mellitus patients.

Adult↗

PubMed1999

[Efficacy of the cuffed oropharyngeal airway in spontaneously breathing patients].

A cuffed oropharyngeal airway (COPA) was used in 20 adult patients for airway management under epidural and brachial plexus block supplemented with light general anesthesia. Insertion of a COPA was successful at first attempt in 17 of 20 patients (85%). Sore throat developed in one patient (5%). Aspiration regurgitation, or laryngospasm was not observed. We conclude that a COPA can be an efficient airway device is spontaneously breathing patients under anesthesia.

Adult↗

PubMed1999

[A clinical trial of acetazolamide for SCA6].

Spinocerebellar ataxia type 6 (SCA 6) is an allelic disorder of episodic ataxia type 2 (EA 2) and is caused by a small CAG repeat expansion in the gene encoding the alpha 1A-voltage-dependent-Ca channel subunit (CACNA 1 A) on chromosome 19p13.1. The disorder starts at adulthood with progressive cerebellar ataxia, and the symptoms often fluctuate at early stage. These clinical features overlap with those of EA 2, which has been known as acetazolamide-responsive ataxia. On this background, we studied the clinical effectiveness of acetazolamide for SCA 6 in 9 consecutive patients. Their clinical severity was serially evaluated by ARS (ataxia rating scale) and gravimetric test, over 32 weeks of oral administration of acetazolamide (250-500 mg/day). Consequently, a significant improvement was observed in ARS and postural sway. Our results indicate that acetazolamide is temporally effective for ameliorating the symptoms of SCA 6. However, its effects for the disease progression need to be examined in more large scales in number and duration.

Acetazolamide↗

PubMed1998

NMDA induced glutamate release from the suprachiasmatic nucleus: an in vitro study in the rat.

The suprachiasmatic nucleus (SCN) has been identified as a pacemaker for mammalian circadian rhythms. Excitatory amino acid receptors, especially N-methyl-D-aspartate (NMDA) receptors, have been considered to play an important role in the transmission of light information from the retina to the circadian clocks in the SCN. In the present study, we showed that application of NMDA at circadian time (CT) 12-15 induced significant glutamate release from the SCN region in vitro. The NMDA-induced glutamate release was blocked by co-application of the NMDA receptor antagonist MK-801, but not by that of tetrodotoxin. These results suggested that glutamate stimulated its own release by activating NMDA receptors. This NMDA-induced glutamate release through NMDA receptor-mediated mechanisms might be involved in NMDA-induced potent phase shifts.

Animals↗