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Y Baba

Publications and source records attributed to Y Baba.

At least 73 records · Page 4Linked to original sources
PubMed2000

Characterization of Ca(2+) channels in rat subthalamic nucleus neurons.

The subthalamic nucleus (STN) plays a key role in motor control. Although previous studies have suggested that Ca(2+) conductances may be involved in regulating the activity of STN neurons, Ca(2+) channels in this region have not yet been characterized. We have therefore investigated the subtypes and functional characteristics of Ca(2+) conductances in STN neurons, in both acutely isolated and slice preparations. Acutely isolated STN cells were identified by retrograde filling with the fluorescent dye, Fluoro-Gold. In acutely isolated STN neurons, Cd(2+)-sensitive, depolarization-activated Ba(2+) currents were observed in all cells studied. The current-voltage relationship and current kinetics were characteristic of high-voltage-activated Ca(2+) channels. The steady-state voltage-dependent activation curves and inactivation curves could both be fitted with a single Boltzmann function. Currents evoked with a prolonged pulse, however, inactivated with multiple time constants, suggesting either the presence of more than one Ca(2+) channel subtype or multiple inactivation processes with a single channel type in STN neurons. Experiments using organic Ca(2+) channel blockers revealed that on average, 21% of the current was nifedipine sensitive, 52% was sensitive to omega-conotoxin GVIA, 16% was blocked by a high concentration of omega-agatoxin IVA (200 nM), and the remainder of the current (9%) was resistant to the co-application of all blockers. These currents had similar voltage dependencies, but the nifedipine-sensitive current and the resistant current activated at slightly lower voltages. omega-Agatoxin IVA at 20 nM was ineffective in blocking the current. Together, the above results suggest that acutely isolated STN neurons have all subtypes of high-voltage-activated Ca(2+) channels except for P-type, but have no low-voltage-activated channels. Although acutely isolated neurons provide a good preparation for whole cell voltage-clamp study, dendritic processes are lost during dissociation. To gain information on Ca(2+) channels in dendrites, we thus studied Ca(2+) channels of STN neurons in a slice preparation, focusing on low-voltage-activated channels. In current-clamp recordings, a slow spike was always observed following termination of an injected hyperpolarizing current. The slow spike occurred at resting membrane potentials and was sensitive to micromolar concentrations of Ni(2+), suggesting that it is a low-threshold Ca(2+) spike. Together, our results suggest that STN neurons express low-voltage-activated Ca(2+) channels and several high-voltage-activated subtypes. Our results also suggest the possibility that the low-voltage-activated channels have a preferential distribution to the dendritic processes.

Action Potentials↗
PubMed2000

C-Type natriuretic peptide inhibits proliferation and monocyte chemoattractant protein-1 secretion in cultured human mesangial cells.

BACKGROUND: Mesangial cell proliferation and matrix accumulation are hallmarks of various progressive glomerular diseases. We examined whether C-type natriuretic peptide (CNP) that is known to regulate the proliferation of vascular smooth muscle cells could modulate these pathological processes using human glomerular mesangial cells (GMCs) in culture. METHODS: Proliferation of GMCs cultured with different concentrations of CNP-22 for 48 h was determined by a colorimetric assay using a tetrazolium salt. Monocyte chemoattractant protein-1 (MCP-1) and type IV collagen secretion into the culture media by GMCs in the presence or absence of CNP-22 were evaluated by ELISA. Expression of mRNA for natriuretic peptide receptor B (NPR-B), a specific receptor for CNP, was examined by reverse transcription polymerase chain reaction (RT-PCR). RESULTS: CNP-22 (1-10 microM) inhibited serum-induced GMC growth in a dose-dependent manner. The amount of MCP-1 in the culture supernatant was increased approximately 2.4-fold by 5 microg/ml of lipopolysaccharide. This increase was inhibited by CNP-22 at 0.1-1 microM in a dose-dependent fashion. CNP-22 (10 microM) inhibited GMC type IV collagen secretion stimulated by 20 ng/ml of platelet-derived growth factor. Expression of NPR-B mRNA was confirmed in GMCs by RT-PCR. CONCLUSIONS: CNP suppresses GMC proliferation and MCP-1 and type IV collagen secretion by GMCs. It may have a therapeutic potential against human proliferative glomerular diseases, especially those with the involvement of monocytes.

Cell Division↗
PubMed2000

[Preparation and clinical evaluation of orally-disintegrating clonidine hydrochloride tablets for preanesthetic medication].

Orally-disintegrating tablets of clonidine hydrochloride, an alpha 2-adrenergic agonist, were prepared by the method of drying an aqueous suspension. The suspension was prepared using powdered lactose, and the composition ratio was 2:1 (powdered lactose: 0.048% clonidine hydrochloride solution). The suspension was dried under 4 +/- 1 degrees C (72 +/- 15% R.H.). We obtained tablets containing clonidine hydrochloride (40 micrograms/tablet). Physical properties of the tablets were as follows: hardness was 4.0 kgf, and disintegration time was 41.7 s (in vitro). In the clinical use, 8 patients, aged 1-2 year and weighing 9-11 kg, received approximately 4 micrograms/kg body weight as clonidine hydrochloride. The tablet was administered 90 min before entering the operating room. All patients were willing to accept the tablet. The quality of separation from parents, sedation and a mask acceptance were excellent on all patients. These results suggest that the orally-disintegrating tablet of clonidine hydrochloride was useful in a clinical situation for the preanesthetic medication of pediatric patients aged 1-2 year.

Administration, Oral↗
PubMed2000

[Degenerative changes in stapedius muscle morphology caused by aging].

Degenerative changes in the morphology of the stapedius muscle caused by aging using a collection of human temporal bones obtained by our department. The diameter of the muscle fibers, the variance in muscle fiber diameter, the ratios of intermuscular connective tissue and muscle to the area of the bone niche for the stapedius muscle, the number of muscle fibers around the tendon, and the adipose cell count were measured for each temporal bone. In total, 80 temporal bones were examined, excluding specimens with facial nerve degeneration, degenerative diseases, middle ear disease and leukemia. Between the ages of 38 fetal weeks and 9 years, the muscle fibers and thin and the variance in fiber diameter is small. The areas of intermuscular connective tissue, muscle and the number of muscle fibers around the tendon do not change between 38 fetal weeks and 60 years. All of the parameters measured showed no significant changes between the ages of 10 and 60 years. The variance in muscle fiber diameter began to increase in specimens aged 70 years or older because some of the muscle fibers had begun to atrophy. Adipose cells were sometimes observed in very old specimens. In contrast to the tensor tympani muscle, in which degenerative changes begin during childhood, atrophic degeneration of the stapedius muscle as a result of aging begins at a very late age. The difference in aging between the stapedius muscle and the tensor tympani muscle is probably related to evidence suggesting that the stapedius muscle contracts in response to acoustic stimulation.

Adolescent↗
PubMed2000

Temporal bone pathology in Wegener's granulomatosis.

This study aimed to demonstrate the temporal bone histopathology of two cases of Wegener's granulomatosis in which the initial symptoms were profound hearing loss and facial nerve palsy respectively. The first case, a woman of 44, suffered profound hearing loss which was remarkably improved by steroid and cyclophosphamide treatment for a time, and which seemed to be caused by invasion from granulation tissue filled in the tympanic cavity. The second case was a 61-year-old woman presenting with the facial nerve palsy. The bony canal of the horizontal portion of the facial nerve was destroyed due to granulation tissue which filled in the tympanic cavity, and granulomatous involvement was observed in the facial nerve. Wegener's granulomatosis can involve the middle ear and/or inner ear, causing hearing loss of conductive, mixed or sensorineural type. Pathogenesis of facial nerve palsy seems to be related to Wegener's granulomatous involvement of facial nerve, because the facial nerve palsy also resolved by using steroid and cyclophosphamide.

Adult↗
PubMed2000

Early glottic squamous cell carcinoma. Predictive value of MR imaging for the rate of 5-year local control with radiation therapy.

PURPOSE: To evaluate MR findings in early (T1 and T2 stages) glottic carcinomas and the predictive value of MR imaging for the rate of 5-year local control with radiation therapy. MATERIAL AND METHODS: Eighty-three patients with early glottic carcinomas were prospectively examined with MR at 1.5 T. MR investigation included unenhanced T1-weighted, T2-weighted, dynamic and contrast-enhanced T1-weighted images. Three patients with presumed advanced diseases on MR were initially treated with total laryngectomy and were excluded from the study. The remaining 80 patients were treated with radiation therapy with curative intent. Tumor detectability, size and relationship to the thyroid cartilage were determined on MR images. The MR findings were then correlated with the rate of local control. RESULTS: Forty-eight of 80 lesions (60%) were detected on MR imaging. All detected lesions but 1 demonstrated increased signal on T2-weighted images. The lesions were best delineated on dynamic images (statistically significant). The 5-year local control rate with radiation therapy was 72%. Univariate analysis revealed clinical T stage, MR detectability, tumor size and relationship to the thyroid cartilage as significant predictors. Multivariate analysis revealed that the relationship to the thyroid cartilage was an independent factor. CONCLUSION: MR provides prognostic information about the results of definitive radiation therapy. To evaluate the tumor extension in lesions detected on precontrast MR images, contrast-enhanced dynamic images should be obtained.

Adult↗
PubMed2000

[Percutaneous mechanical thrombectomy for thrombosed vessels with a hydrolyser (hydrodynamic thrombectomy catheter): clinical experience].

A hydrodynamic thrombectomy catheter was prospectively evaluated for the treatment of thrombosed vessels. Seven patients (7 males: age range from 56 to 82 years; mean age: 79 years) presenting with acute or chronic occlusion of peripheral native arteries (n = 6) and dialysis shunt (n = 1) were treated with the hydrolyser (Cordis, Johnson and Johnson, Japan). Mean occlusion time was 135 days (range: 2-300 days), and mean thrombus length 16 cm (range: 5-20 cm). Removal of the thrombus was successful in five patients (71%), regardless of the length of the thrombus. Mean procedure time was 20 minutes (range: 15-30 minutes). No major complications occurred. Adjunctive thrombolysis was required for persistence of the residual thrombosed distal vessel in one patient. Adjunctive balloon angioplasty was performed in two patients (one native vessel and one dialysis shunt), and stent placement was performed in one patient (dialysis shunt). In two unsuccessful cases, the hydrolyser could not be advanced to the distal side because of the solid thrombus. Therefore, thrombolytic therapy was chosen. However, this therapy failed because the guidewire did not pass within the thrombus. Surgery was performed in these two patients. We conclude from this clinical experience that percutaneous thrombectomy with a hydrolyser is a promising technique for the treatment of thrombosed vessels. Especially in the acute stage of thrombosed occlusion, percutaneous thrombectomy with a hydrolyser is superior to thrombectomy with a Fogarty balloon catheter because of its shorter procedure time and fewer complications.

Acute Disease↗
PubMed2000

[Giant osteoma of the temporal bone with otitis media: a case study].

A 71-year-old female presented with a giant osteoma of the right temporal bone and otitis media. Computed tomography (CT) and magnetic resonance imaging (MRI) confirmed the presence of the giant osteoma. An operation was performed to alleviate the difficult-to-treat otitis media and to address the related cosmetic problem. During the operation, three-dimensional CT (3D-CT) was very helpful in understanding the relationship between the tumor and the peripheral structures. Removal of the tumor improved the patient's otitis media. Osteoma of the temporal bone is rare. Only twenty-one cases of mastoid osteoma have been reported in Japan. In the present study, we review osteomas of the temporal bone and discuss their management.

Aged↗
PubMed2000

Dynamic helical CT of T1 and T2 glottic carcinomas: predictive value for local control with radiation therapy.

BACKGROUND AND PURPOSE: Tumor volume and cartilage invasion have been suggested as prognostic factors of glottic carcinomas following definitive radiation therapy. Radiologic examinations provide additional information regarding the deep extension of tumor. We determined whether dynamic helical CT can predict local control of early (T1 and T2 stage) glottic carcinomas treated with definitive radiation therapy. METHODS: Sixty-eight patients with early glottic carcinoma evaluated on pretreatment dynamic helical CT were treated with definitive radiation therapy. Tumor detectability, maximum dimension, tumor volume, and involvement of anatomic subsites (anterior commissure, ventricle, subglottic region, and thyroid and arytenoid cartilages) were determined by consensus by three radiologists without previous knowledge of the clinical information. The CT findings were correlated with local control. RESULTS: The two-year local control rate was 76%; 91% for T1 and 60% for T2 lesions. Univariate analysis revealed clinical T stage, tumor detectability, maximum dimension, tumor volume, anterior commissure involvement, ventricle involvement, and thyroid cartilage involvement as significant prognostic factors. Thyroid cartilage involvement was an independent predictor by multivariate analysis. The lesions separate from the thyroid cartilage had a 95% probability of local control, whereas the lesions adjacent to the cartilage had only a 42% control rate. CONCLUSION: Dynamic helical CT provides prognostic information for the results of definitive radiation therapy. Patients with a tumor adjacent to the thyroid cartilage had an increased risk of local failure.

Adult↗
PubMed2000

[Extended spontaneous spinal epidural anterior hematoma over multiple spinal segments. A case report].

We reported a case of extended spontaneous spinal epidural hematoma over multiple spinal segment. A 68-year-old man presented with sudden onset of back pain. He rapidly developed tetraplegia within 15 minutes. On admission, he showed tetraplegia, sensory loss below C4 dermatome, right Horner's sign and bilateral Babinski's signs. These neurological signs gradually improved and disappeared completely within 5 hours. MR imaging showed extended hematoma in the anterior part of spinal epidural space. Spinal angiogram showed no vascular anomaly. The patient had nine years history of antiplatelet therapy, which would produce this episode of the spinal epidural hematoma. The hematoma located in the anterior part of the epidural space and extended over multiple spinal segments was characteristic features in this case. In the case which could have early neurological recovery, conservative therapy might be indicated.

Aged↗
PubMed2000

Preservation of rat palatal scar tissue myofibroblasts in organ culture.

In order to modulate palatal scar tissue, especially its myofibroblastic component, there is a pressing need for an in vitro model of this tissue. In the present, study we established an organ culture model of the rat palatal scar tissue. After excision of palatal mucoperiosteum, explants from the developing immature scar tissue and from the normal palatal mucosa were used to observe myofibroblasts in vivo and their maintenance in organ culture. Explants were cultured at the gas-liquid interface in serum-free Waymouth's MB 752/1 medium and in a humid atmosphere containing 55% O2/5% CO2 in air at 37 degrees C for 3 days. Viability of the cultured explants was evaluated with morphological and histological criteria and BrdU incorporation. After organ culture, the scar tissue showed good preservation of the in vivo histology. The myofibroblasts and smooth muscle cells of the cultured scar tissues showed continuous expression of alpha-smooth muscle actin (alpha-SMA), mimicking the in vivo situation. In the normal tissues, only smooth muscle cells of the blood vessels expressed alpha-SMA. These results demonstrate that the established model provides a useful in vitro experimental tool for investigating the palatal scar tissue in general and its myofibroblasts in particular.

Actins↗
PubMed1999

Capillary affinity gel electrophoresis: new technique for specific recognition of DNA sequence and the mutation detection on DNA.

The present state of studies on capillary affinity gel electrophoresis, which is a new technique for the specific recognition of a target DNA sequence, is reviewed. This article includes the principle, theory, methods, and applications of this technology. The great potential of capillary affinity gel electrophoresis for the sequence-specific recognition of DNA and the detection of mutations in specific genes is illustrated.

Adenine↗
PubMed1999

Unusual capillary electrophoretic behavior of triplet repeat DNA.

We investigated the electrophoretic behavior of triplet repeat DNA fragments by capillary electrophoresis and found triplet repeat DNA fragments showed unusual mobilities compared with those of commercially available DNA molecular marker. The electrophoretic data are analyzed by means of Ogston model and the mechanism of a change in mobility of triplet repeat DNA is discussed. The unusual mobilities are caused by the characteristic higher-order structure formed by GC-rich triplet repeat DNA.

DNA↗
PubMed1999

Dendritic Ca2+ transient increase evoked by wind stimulus in the cricket giant interneuron.

In vivo Ca2+ imaging was applied to the cricket median giant interneuron (MGI), to visualize the dendritic processing of mechanosensory signals. Wind stimulation (air-puff) to the cerci induced a transient increase in the cytosolic Ca2+ concentration ([Ca2+]i) in the MGI with a latency of a few seconds, suggesting the release of Ca2+ from the intracellular store site in the MGI. The amplitude of the transient increase in [Ca2+]i in the dendrites depended on the direction of the air-puff, and the increase in [Ca2+]i evoked by the air-puff was suppressed by the hyperpolarizing current injection which blocked the generation of action potentials. These results indicate that the action potential is necessary to the direction-sensitive increase in [Ca2+]i induced by wind stimulation.

Animals↗
PubMed1999

Factors that predict intrahepatic recurrence of hepatocellular carcinoma in 81 patients initially treated by percutaneous ethanol injection.

BACKGROUND: In Japan, where liver transplantation has not been used to treat patients with hepatocellular carcinoma (HCC), percutaneous ethanol injection (PEI) has been employed for those with small HCCs that are not amenable to surgical resection. In the current study, the authors evaluated PEI as a treatment for HCC patients by studying recurrence rates and survival after treatment. They then examined the clinicopathologic factors that predicted patterns of local and distant intrahepatic recurrence. METHODS: For 81 patients who underwent PEI as initial therapy between 1990 and 1997, the cumulative recurrence and survival rates and their correlations with 16 clinicopathologic factors were studied using the Kaplan-Meier method. RESULTS: The 3-year overall cumulative rates of intrahepatic recurrence and survival were 81% and 84%, respectively. At the end of the observation period, intrahepatic recurrence was detected in 56 patients (69%). In 21 (38%) of 56 patients, local recurrences were significantly associated with earlier stages of underlying cirrhosis, decreased indocyanine green retention at 15 minutes (ICG R15), larger tumor size, and histologically advanced tumor grade. Distant intrahepatic recurrence was also significantly associated with liver function and ICG R15. CONCLUSIONS: PEI is most effective as the initial treatment for patients with well-differentiated HCC when the tumor is less than 15 mm in greatest dimension. However, local recurrence depends predominantly on the biologic characteristics of the tumor, regardless of the efficacy of PEI. Surgical resection of HCC should be considered, especially for patients with mild liver dysfunction.

Aged↗