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Biomedical subjects

M Maehara

Publications and source records attributed to M Maehara.

At least 19 recordsLinked to original sources
PubMed2006

Gadolinium-enhanced magnetic resonance imaging after percutaneous vertebroplasty does not improve the short-term prediction of new compression fractures.

PURPOSE: To investigate the relationships between contrast-enhanced magnetic resonance imaging (MRI) findings and new compression fractures occurring after percutaneous vertebroplasty (PVP) in order to determine the necessity of contrast-enhanced MRI. MATERIAL AND METHODS: The material comprised 13 consecutive patients (27 vertebrae) with compression fractures who underwent vertebroplasty. Twenty-nine adjacent vertebrae were monitored for new compression fractures. We performed contrast-enhanced MRI within the 5 days following PVP. RESULTS: The 29 adjacent vertebrae displayed 10 enhanced lesions and 19 vertebral bodies without enhancement-unenhanced lesions on MRI within the 5 days after PVP. In 4 out of 10 vertebrae, enhanced lesions were seen within the 5 days after PVP, but no abnormalities were seen on preoperative MRI. In these 4 vertebrae, new compression fractures were seen within the 1 month following PVP. In the other 6 vertebrae, enhanced lesions were seen within the 5 days after PVP, and these signal changes were detected by preoperative MRI in the same area. In 3 of these 6 vertebrae, new compression fractures occurred at 4, 8, and 9 months after PVP, respectively. However, all of the enhanced lesions were detectable on unenhanced MRI, which was conducted at the same time as enhanced MRI. CONCLUSION: New compression fractures after PVP may be predicted with early postoperative MRI. Contrast-enhanced MRI does not improve detection of the new lesions.

Aged↗
PubMed2001

[Effects of smoking on pulmonary function: a cross-sectional and longitudinal study].

Cross-sectional and longitudinal studies were done to investigate the influence that a change in smoking habit can have on the pulmonary function. Seventeen hundred and thirty nine people (698 men, 1,041 women), 39 years of age or older, from the population of a farming village located in the central part of Miyazaki Prefecture were examined. A population-based cohort study with a 4-time observation was done over an interval of 12 years. Forced vital capacity (FVC) and forced expiratory volume in one second (FEV1.0) were used as the index of respiratory function, and adjusted annual change of FVC and adjusted annual change of FEV1.0 were used as a pulmonary function inspection index. There was a statistical significance in both %FVC and %FEV1.0 to the predicted values between smokers and non-smokers at the beginning of observation. The adjusted annual change of FVC both of male- and female-smokers and the adjusted annual change of FEV1.0 of male-smokers was higher than those of non-smokers in the longitudinal study. Percent FVC, %FEV1.0 and the adjusted FEV1.0 change of former male-smokers were lower than those of continuing smokers. In addition to %FVC and %FEV1.0, annual change of FVC and annual change of FEV1.0 were important predictors of pulmonary function related to cigarette smoking.

Adult↗
PubMed1999

Concomitant administration of sodium dichloroacetate and thiamine in west syndrome caused by thiamine-responsive pyruvate dehydrogenase complex deficiency.

We treated a female patient with West syndrome caused by thiamine-responsive pyruvate dehydrogenase complex (PDHC) deficiency. Infantile spasms occurred in association with elevated blood and CSF lactate concentrations; these symptoms disappeared when lactate concentrations had been lowered by treatment with concomitant sodium dichloroacetate (DCA) and high dose thiamine. Sequencing the patient's PDHC E(1)alpha subunit revealed a substitution of serine for glycine at position 89 in exon 3 (G89S). This mutation must be a de novo mutation because it was not found in either parents' genome DNA. To our knowledge, five previously described patients with PDHC deficiency have displayed the West syndrome. All six known patients, including our own, were female, even though an approximately equal number of males and females have been identified with PDHC deficiency and overall West syndrome occurs somewhat more frequently in males. These results indicated that West syndrome occurred more frequently in female patients with PDHC deficiency. It is suggested that lactate concentration should be measured in patients with West syndrome for potential PDHC deficiency, especially in females.

Amino Acid Substitution↗
PubMed1999

Three types of voltage-dependent calcium currents developing in cultured human neuroblastoma cells.

Voltage-dependent calcium currents (ICa), which developed in cultured human neuroblastoma cells (NB-I), were studied using a whole-cell recording technique. Three types (T-, N- and L-type) of ICa were identified based on their biological and pharmacological properties. The T-type ICa was observed in about 60% of the cells from day 2 to day 12 and in about 20% after day 14. Likewise, the amplitude gradually decreased from -61.7 +/- 10.1 pA on day 2 to -18.3 +/- 9.1 pA on day 18. The N-type ICa appeared on day 6, with the number of cells exhibiting this current increasing up to 90.9% (-73.4 +/- 16.0 pA) on day 14 and immediately decreasing thereafter. The L-type ICa was observed in 50.0% of the cells on day 2, increasing to 84.6% of the cells on day 6 and remaining thereafter, while the amplitude gradually increased from -37.8 +/- 14.0 pA on day 2 to -158.8 +/- 22.8 pA on day 18, and decreased thereafter. These findings indicate that the expression of the voltage-dependent Ca2+ channels is strongly regulated by the developmental stage of the cell.

Calcium Channels↗
PubMed1996

Mechanisms of T-type calcium channel blockade by zonisamide.

We investigated the effects of zonisamide, a new antiepileptic drug, on voltage-dependent T-type calcium current (ICa) in cultured neuroblastoma cells of human origin (NB-I). Zonisamide reduced T-type ICa in a concentration-dependent manner without evoking any change in its inactivation kinetics or voltage dependence of action. The mean percent reduction was 38.3 +/- 5.8% at 50 microM. Further, zonisamide shifted the inactivation curve approximately 20 mV negative compared to the control. These resting blocking actions suggest that zonisamide shifts the channel population toward the inactivation state, allowing fewer channels to open during membrane depolarization. The blockade of T-type calcium channels by zonisamide could suppress an important component of inward current that underlies epileptiform cellular bursting, thereby inhibiting the spread of seizure activity.

Anticonvulsants↗
PubMed1996

[Glucose intolerance after percutaneous ethanol injection therapy (PEI) in liver cirrhosis patients with hepatocellular carcinoma].

We studied the effect of percutaneous ethanol injection therapy (PEI) on glucose tolerance in liver cirrhosis patients with hepatocellular carcinoma. All of 10 patients underwent PEI and aspiration biopsy of the tumor on separate day. Two-time oral glucose tolerance tests (OGTT), before and after PEI, were performed in all patients. There were no significant changes in blood glucose and insulin chronologically measured on aspiration biopsy and PEI. To detect changes in glucose tolerance, we compared the results of OGTT before PEI with those of OGTT after PEI. On the basis of results of OGTT before PEI, patients were classified to impaired glucose tolerance group (4) and diabetes mellitus group (6). Blood glucose at 180 minutes on OGTT after PEI showed significantly higher value than that of OGTT before PEI, but insulin response was not suppressed. From these experiments we speculate that exaggerated insulin resistance due to injected ethanol may be one of the factors influencing glucose tolerance after PEI.

Aged↗
PubMed1995

Three types of voltage-dependent calcium currents in cultured human neuroblastoma cells.

The voltage-dependent calcium current (ICa) in cultured human neuroblastoma cells (NB-I) was studied by whole-cell recording. The low-threshold current (Il), the high-threshold, fast inactivating current (Ih.f.), and the high-threshold, slow inactivating current (Ih.s.) were identified. Il. was blocked by Ni2+. Ih.f. was blocked by omega-conotoxin GVIA. Ih.s. was blocked by nifedipine, and enhanced by Bay K 8644. These characteristics indicate that Il, Ih.f. and Ih.s. are consistent with the T-, N- and L-type ICa, respectively.

Calcium↗
PubMed1994

Antiepileptic drugs--calcium current interaction in cultured human neuroblastoma cells.

The voltage-dependent calcium channel current (ICa) in the neuroblastoma cell line of human origin (NB-I) was studied by the whole-cell clamp recording. Three types of ICa were identified in NB-I cells. Our electrophysiological and pharmacological findings have suggested that these three types of ICa are consistent with the T-, N- and L-type ICa, respectively. Phenytoin (PHT) inhibited T-type ICa by 13.0% at a concentration of 5 microM, and L-type ICa by 6.3% at a concentration of 100 microM. At a concentration of 100 microM, carbamazepine (CBZ) inhibited T- and L-type ICa by 6.0% and 5.9%, respectively. At a concentration of 50 microM, sodium valproate (VPA) blocked T- and L-type ICa by 6.1% and 47.5%, respectively. At a concentration of 50 microM, zomisamide (ZNS) inhibited T- and L-type ICa by 38.3% and 41.9%, respectively. Na+ channel blockade has been reported to be responsible for the clinical efficacy of PHT or CBZ. Inhibition of T-type ICa by PHT may enhance the efficacy of its anticonvulsant action. CBZ had little effect on ICa. The anticonvulsant activity may be related to the blockade of T-type ICa in the case of VPA and ZNS.

Anticonvulsants↗
PubMed1993

Lateral gap junction connections between retinal amacrine cells summating sustained responses.

Vertebrate retinal amacrine cells produce transient or sustained responses. Sustained depolarizing amacrine cells in the dace retina were identified by their intracellularly recorded responses to light flashes. The response amplitude produced a notable spatial summation which exceeded that of individual dendritic arbors. When sustained type amacrine cells were intracellularly injected with Lucifer Yellow and biocytin, there was extensive transfer of biocytin, but not Lucifer Yellow, to surrounding cells with similar cellular morphology. Ultrastructural analysis of the interconnections by electron microscopy revealed the presence of gap junctions at the contact area, which did not include conventional synapses. Present results demonstrate that sustained response amacrine cells make direct electrical connections between the cells of the same type and electrical coupling may contribute to extension of their receptive fields.

Animals↗
PubMed1993

Dimethyl sulfoxide (DMSO) increases expression of sialyl Lewis x antigen and enhances adhesion of human gastric carcinoma (NUGC4) cells to activated endothelial cells.

Dimethyl sulfoxide (DMSO) exerts a number of biological effects including the promotion of cell differentiation in cultured cells. In this study, we examined the effect of DMSO on the adhesion of tumor cells to endothelial cells. In vitro treatment of human gastric adenocarcinoma (NUGC4) cells with DMSO resulted in increased adhesion to interleukin-I (IL-I)-activated human endothelial cells compared with DMSO-untreated NUGC4 cells. In flow cytometry, treating NUGC4 cells with DMSO enhanced the expression of sialyl Lewis x (sialyl Le(x)) and sialyl dimeric Le(x) antigens on their surface. Also, the binding of Limulus polyphemus agglutinin (LPA), which specifically binds to cell-surface sialic acids, was increased by DMSO. The adhesion of DMSO-treated NUGC4 cells to activated endothelial cells was blocked by neuraminidase pre-treatment of tumor cells or by antibody against either endothelial leukocyte adhesion molecule-I (ELAM-I) or sialyl Le(x). Thus, it is suggested that enhanced adhesion following DMSO treatment is mediated by the interaction of sialyl Le(x) expressed on NUGC4 cells with ELAM-I of endothelial cells. The modulation of sialyl Le(x) antigen by DMSO provides a useful system for studying the regulatory mechanism of Lewis-related carbohydrate antigens and also for understanding the metastatic properties of cancer cells.

Antibodies, Monoclonal↗
PubMed1993

[Modes of spread and surgical strategy for gallbladder carcinoma with subserosal invasion].

The mode of spread and the prognosis were investigated in 22 patients with resected gallbladder carcinoma invading the subserosal layer. By the Kaplan-Meier method, the 5-year survival rate was 68.8% in patients receiving curative or relatively noncurative resection. On the other hand, no patient survived for more than 3 years after noncurative resection. The mode of subserosal infiltration was classified according to the general rules for gastric cancer study. At least systemic lymph node dissection (R2) should be performed in patients with ss alpha cancer, because lymph node metastasis in these patients were confined to the 1st group. More extensive lymph node dissection (R2 with 9, 16) is essential for patients with ss beta and ss gamma, because lymph node metastasis to at least the 2nd group were seen in 75% of them. The surgical margin was positive for cancer in all patient with infiltration of the hepatoduodenal ligament. Therefore, it was considered that hepatoligamentectomy should be performed in these patients to obtain a cancer free surgical margin. Among patients undergoing curative or relatively noncurative resection, the recurrence rate was 43% in those with lymph node metastasis and 50% in those with DNA aneuploidy. Therefore, it appears that adjuvant chemotherapy should be given to such patients.

Aged↗
PubMed1992

The presence of concanavalin-A(Con-A)-like molecules on natural-killer (NK)-sensitive target cells: their possible role in swainsonine-augmented human NK cytotoxicity.

In the present study we examined the expression of concanavalin-A(Con-A)-like molecules on natural-killer (NK)-sensitive target cells and investigated their possible role in the human NK-cell phenomenon. The incubation of either peripheral-blood lymphocytes (PBL) or large granular lymphocytes (LGL) with swainsonine (SW), an inhibitor of mannosidase II, resulted in the augmentation of cytotoxicity against K562 leukemia cells. The enhanced cytotoxicity was associated with increased binding of fluorescein isothiocyanate-conjugated Con-A to SW-treated effector cells, and immunofluorescence staining of the target K562 cells using goat anti-Con-A antibody (Ab) showed a significant positive shift in the flow cytometric pattern. Electrophoretic separation and immunoblotting analysis revealed that 4 components with a molecular weight of approximately 95, 80, 60 and 50 kDa were recognized by anti-Con-A Ab from the detergent-extract of K562 cells. The addition of Con-A during the antibody incubation step of the Western blotting abolished their expression, thus excluding non-specific binding of the antibody. The addition of Con-A also strongly inhibited the cytotoxicity of SW-treated effector cells (PBL or LGL) against K562 cells, and this inhibition was abolished by 40 mM alpha-methyl-mannopyranoside (alpha-MM), which binds to Con-A. Furthermore, Con-A increased the binding frequency of SW-treated LGL to K562, in spite of the inhibited cytotoxicity, and this effect could be neutralized by the further addition of alpha-MM. Our results suggest that Con A-like molecules might play an important role in cell-cell interactions between SW-treated effector cells and NK target cells.

Adenosine Triphosphate↗
PubMed1992

Hyperpolarizing interplexiform cell of the dace retina identified physiologically and morphologically.

One type of interplexiform cell (IPC) in the dace retina was discriminated physiologically from other cell classes and identified morphologically with HRP staining. This type responded with slow hyperpolarizing potentials to white diffuse light, and in addition a slow hyperpolarization (after potential) was observed after the cessation of light with relatively high intensities. The latency of the ON phase of the response was always longer than that of the second-order neurons and the amacrine cells. Morphologically, this type of IPC was similar in appearance with the dopaminergic IPC. The conventional synaptic specialization between this type of IPC and horizontal cells was observed, and the IPC was presynaptic.

Animals↗