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Biomedical subjects

A Ishihara

Publications and source records attributed to A Ishihara.

At least 145 records · Page 8Linked to original sources
PubMed1993

Long-term follow up of ventricular endocardial pacing leads. Complications, electrical performance, and longevity of 561 right ventricular leads.

Five hundred and sixty-one endocardial pacing leads implanted in the right ventricle of 502 patients between 1971 and 1990 were followed for up to 17 years regarding their complications, stimulation threshold behavior, and overall longevity. Lead tip dislodgment occurred in 16 leads (2.9%), in 14 of which dislodgement occurred within 2 months after implantation. The incidence of dislodgement was significantly smaller in tined leads than in nontined leads. Lead conductor fracture occurred in 19 leads (3.4%), in 15 of which fracture occurred within 5 years after implantation. Two particular sites of lead fracture were identified; i.e., one within the pacemaker pocket and the other at a particular point in the subclavian vein between the clavicle and the first rib. Fixation ligature in the former site and the venopuncture point for lead insertion in the latter site are thought to be related to lead fracture. Other complications included insulator break in 3 leads (0.5%), exit block in 7 leads (1.2%), and poor sensing in 2 leads (0.4%). The cumulative survival of leads was 94.1 +/- 2.7% (mean +/- 95% confidence interval) at 5 years, 86.3 +/- 6.3% at 10 years, and 74.2 +/- 14.0% at 15 years after implantation. The minimal stimulation threshold, lead impedance and R wave amplitude were all found to be stable for up to 10 years, and there were no tendencies toward higher stimulation threshold during the observation period of this study.

Electrodes, Implanted↗
PubMed1993

Immunohistochemical and electron microscopic studies of substance P in guinea pig nasal glands.

The distribution of substance P-like immunoreactive (SP-IR) nerve endings in the nasal gland of the guinea pig was studied by using histochemical techniques to detect mucous glycoprotein and immunohistochemical techniques for SP, in combination with electron microscopy. Most nasal glands were negative for both AB and periodic acid-Schiff (PAS) staining. The SP-IR nerve fibers were found to form a network around these glands. The SP-IR nerve endings were located in the region between interdigitated cytoplasmic folds of acinar cells and along the cell surface, as well as in the intercellular spaces of proximal ducts. The acini which closely contacted with SP-IR nerve endings were serous in type. Our results suggest that substance P may contribute to the regulation of serous gland secretion in the guinea pig nasal mucosa.

Animals↗
PubMed1993

[Relationship of an extracellular matrix protein, tenascin and breast diseases].

Tenascin is an extracellular matrix glycoprotein consisting of six disulfide-linked subunits with molecular masses of 190-250 kDa. Molecular analysis of the tenascin gene revealed that it contains a region homologous to epidermal growth factor genes, repetitive sequences of the type III fibronectin and the fibrinogen gene. Culture studies have shown that tenascin has multiple functions including cell attachment and detachment, promotion and inhibition of neural crest cell migration, cell growth stimulation and hemagglutination. Immunohistochemically, tenascin shows a characteristic and spatially restricted distribution. In mouse mammary glands, tenascin protein is demonstrated in the dense mesenchyme present around growing epithelia during embryogenesis and oncogenesis. Tenascin is expressed in normal human adult breast tissue and benign conditions, although it is expressed more abundantly in breast cancer tissue. Prominent tenascin staining is found in dense cancer-mesenchymal junctions. The staining positivity is significantly correlated with metastasis to regional lymph nodes and tumor grade. Tenascin positive patients have a significantly poorer prognosis compared with tenascin-negative patients. Although the biological functions of tenascin in breast cancer tissue have not yet been clearly elucidated, tenascin staining in surgical tissue specimens might be useful when applied to detect a subgroup of breast cancer patients who have a poorer prognosis.

Animals↗
PubMed1993

The fish epidermal keratocyte as a model system for the study of cell locomotion.

Keratocytes provide an excellent system for the study of locomotion because their simple shape allows the description of basic principles that govern their movement. The graded radial extension (GRE) model is a kinematic description of keratocyte locomotion which relates cell shape to movement. It predicts the circumferential motion of morphological features within the plane of the moving cell. The detection of circumferential motion allows the GRE model to be distinguished from the process of spreading and parallel extension. The circumferential motion of morphological features and the curvature of lines "photomarked" into macromolecular assemblies can be explained in terms of the regulation of actin filament dynamics. The GRE model can thus relate molecular scale events to the locomotion of a whole cell. The principles of the GRE model may operate in other cell types especially since different modes of locomotion appear to be part of the same phenomenon.

Animals↗
PubMed1993

A case of radical resection for solid cystic tumor of the pancreas with widespread metastases in the liver and greater omentum.

Solid cystic tumor (SCT) of the pancreas is known to be a low-grade malignant tumor and distant metastasis is very rare. A 50-year-old Japanese female was hospitalized because of a large mass in the upper abdomen. Computerized tomography revealed a large calcified tumor in the body-tail of the pancreas, and multiple liver tumors. Abdominal angiography demonstrated the pancreatic tumor and multiple hepatic tumors as a hypervascular mass, and disclosed a small tumor stain in the branch of the right gastroepiploic artery. The patient underwent a distal pancreatectomy with splenectomy, extended right hepatic lobectomy, and removal of the omental metastases. Histopathological and electron microscopic studies made a definitive diagnosis of SCT. She is well without any signs of tumor recurrence 1 yr and 2 months after the operation. This may be the first patient receiving simultaneous radical resection for both the main tumor and widespread distant metastases.

Cysts↗
PubMed1992

Subaortic stenosis caused by an unusual fibrous blood-filled cyst of the left ventricle with outflow tract obstruction associated with a ventricular septal defect.

A large blood-filled cyst formed from a fibrous tissue tag of a right ventricular septal aneurysm was successfully resected. This cyst, which was causing subaortic stenosis, was attached to the margin of the closed ventricular septal defect and not to the mitral valve itself nor the papillary muscle of the left ventricle.

Aortic Stenosis, Subvalvular↗
PubMed1992

Basic fibroblast growth factor ameliorates learning deficits in basal forebrain-lesioned mice.

The effect of basic fibroblast growth factor (bFGF) treatment on memory and learning performance ability was investigated in basal forebrain (BF)-lesioned mice. Eight-week-old male ddY mice underwent bilateral BF lesions by delivery of radiofrequency current. Basic FGF (5 or 50 ng/side) was microinjected into the same location immediately after lesioning. From fifteen days after the treatment, a step-through type passive avoidance test was performed daily for 10 days. Lesioned animals showed severe impairment in the acquisition process in this task, but not in the retention process. Basic FGF improved the step-through performances; step-through latency was elongated in a dose-dependent manner on the first test trial day and the mean time required to reach the acquisition criterion was shorter than in the vehicle-treated control group. However, bFGF did not alter the cortical choline acetyltransferase (ChAT) activity decrement induced by BF lesion. These results suggest that bFGF ameliorates the memory deficit without affecting the cortical ChAT activity.

Analysis of Variance↗
PubMed1992

New technique using intraductal ultrasonography for the diagnosis of diseases of the pancreatobiliary system.

Intraductal ultrasonography (IDUS), a new technique for visualizing arterial structures, operates at an ultrasound frequency of 30 MHz to produce high resolution, cross-sectional images in real time. The purpose of this study was to provide a basis for interpreting IDUS images in vitro. We also attempted to determine the clinical usefulness of the IDUS system in diagnosing pancreatobiliary diseases in vivo. IDUS echograms of both the bile duct (BD) and main pancreatic duct (MPD) from autopsy specimens of 15 patients demonstrated three distinct layers with a fine reticular pattern in the pancreas in vitro. In clinical cases, the MPD and BD of four patients could be scanned by inserting the IDUS catheter via the major papilla without requiring endoscopic sphincterotomy. We hope that IDUS will become routine in scanning the BD and MPD to achieve early and accurate diagnoses of pancreatobiliary diseases.

Adenoma, Bile Duct↗
PubMed1992

Fibre type composition of the soleus muscle in hypoxia-acclimatised rats.

Fibre type composition in the soleus muscle was studied in second generation male and female Sprague-Dawley rats bred at 460 Torr (hypobaric hypoxia). In control male and female rats (bred at sea level atmospheric pressure) the percentage of slow twitch oxidative (SO) fibres increased, and the percentage of fast twitch oxidative glycolytic (FOG) fibres decreased over time. In male hypoxic rats fibre type composition did not change. However, in female hypoxic rats the percentage of SO fibres increased, and that of FOG fibres decreased over time. The female hypoxic rats had a higher percentage of FOG fibres and a lower percentage of SO fibres than age-matched control rats. These findings indicate that hypoxia-acclimatised rats have a relatively high percentage of FOG fibres, and that this is due to inhibition of the fibre type shift from FOG to SO, which occurs during normal development. Furthermore, there is a sex-related difference in the change in fibre type composition in hypoxia-acclimatised rats.

Acclimatization↗
PubMed1992

[Imaging diagnosis of the insulinoma--the clinical usefulness of intraductal ultrasonography of the pancreas and color Doppler sonography].

5 cases of small-sized insulinoma of the pancreas were studied to evaluate the ability of diagnostic imaging techniques to determine tumor location. Techniques used were extracorporeal ultrasonography, endoscopic ultrasonography (EUS), angiography, percutaneous transhepatic portal catheterization and CT. EUS was superior to the other modalities in diagnosing the location of insulinomas. We employed Color Doppler (CD) ultrasonography in one case and obtained color expression in the tumor and a pulsatile wave in the FFT analysis. Intraductal sonography of the pancreas (IDSP) was also performed in this case resulting peripheral echo-lucent, central echogenic mass. From these results, we expect that CD and IDSP will be useful in clinical application for diagnosing various tumors.

Adult↗
PubMed1992

[Surgical treatments of nonconfluent pulmonary arteries with congenital cardiac defects].

Pulmonary artery angioplasty or reconstruction was performed in seven patients with nonconfluent pulmonary arteries and congenital cardiac defects. Age of these patients were ranged from 6 months to 41 years old. Five of them had pulmonary truncal atresia and complex cardiac anomalies. Two of these five patients demonstrated nonconfluent pulmonary arteries due to deformities at ductal insertion of pulmonary arteries. Three patients had had previous systemic to pulmonary artery shunt operations which caused pulmonary artery distortions. Other two patients had intrapulmonary arterial obstructions due to pulmonary artery thrombosis. Patch pulmonary artery plasty was carried out in three patients, dilatation of severe stenotic pulmonary artery was done in one patient simultaneously with pulmonary valvotomy. Central shunt operation was added in one patient with the pulmonary artery which was unable to be reconstructed. Last two patients underwent intrapulmonary artery reconstruction with the rolled pericardial graft. Hospital death occurred in one patient with unproperly increased pulmonary blood flow by central shunt. Average follow-up period of these six survivors after operation was 1.4 +/- 0.8 years. As definite repairs, two patients had Fontan operation, two patients had right ventricle to pulmonary artery reconstruction. And remaining two patients are still to be followed until sufficient growth of pulmonary artery suitable for Fontan operation.

Adolescent↗
PubMed1992

Phenotypic and functional analysis of lamina propria mononuclear cells from colonoscopic biopsy specimens in patients with ulcerative colitis.

Phenotypic and functional analysis was performed with lamina propria mononuclear cells (LPMCs) isolated from colonoscopic biopsies in 27 patients with ulcerative colitis (UC). The proportion of T lymphocytes displaying HLA-DR antigens, interleukin 2 (IL-2) receptor, and transferrin receptor was greater in active UC than in control diseases. When LPMCs were cultured with IL-2 or phytohemagglutinin for 72 h, there were no significant differences in the proportion of cells bearing these activation markers between active UC and controls. The proportion of CD56+ cells and lymphokine-activated killer (LAK) cell activity was lower in LPMCs from active UC than in control cells, and depletion of CD56+ cells from control lamina propria cells essentially eliminated LAK cell activity. Mucosal T lymphocytes may be activated in vivo during active inflammation in UC, and lower levels of intestinal LAK cell activity may be related to the decrease of CD56+ cells under these conditions.

Adolescent↗
PubMed1992

Effect of hypobaric hypoxia on fiber type composition of the soleus muscle in the developing rat.

The fiber type composition of the soleus muscle was investigated in male Sprague-Dawley rats exposed to hypobaric hypoxia of 460 mm Hg from 5 to 12 weeks of age. The muscle fibers were classified as fast-twitch oxidative (FO) and slow-twitch (S) on the basis of adenosine triphosphatase (ATPase) and succinate dehydrogenase (SDH) reactions. Intermediate fibers (INT) with intermediate ATPase and high SDH reaction intensities were also examined. A type shift of muscle fibers from FO to INT and S was found in the control group during development. After exposure to hypoxia, the hypoxia group had a significantly greater percentage of FO fibers than the age-matched control group. There was no significant change in the total number of fibers in the muscle during development and after exposure to hypoxia. These results indicate that the increased percentage of FO fibers found in the developing rat under hypoxic conditions is due to a hypoxia-induced inhibition of the type shift of muscle fibers from FO to S during development.

Animals↗
PubMed1991

Direct observation of brownian motion of lipids in a membrane.

Nanovid microscopy, which uses 30- to 40-nm colloidal gold probes combined with video-enhanced contrast, can be used to examine random and directed movements of individual molecules in the plasma membrane of living cells. To validate the technique in a model system, the movements of lipid molecules were followed in a supported, planar bilayer containing fluorescein-conjugated phosphatidylethanolamine (Fl-PtdEtn) labeled with 30-nm gold anti-fluorescein (anti-Fl). Multivalent gold probes were prepared by conjugating only anti-Fl to the gold. Paucivalent probes were prepared by mixing an irrelevant antibody with the anti-Fl prior to conjugation. The membrane-bound gold particles moved in random patterns that were indistinguishable from those produced by computer simulations of two-dimensional random motion. The multivalent gold probes had an average lateral diffusion coefficient (D) of 0.26 x 10(-8) cm2/sec, and paucivalent probes had an average D of 0.73 x 10(-8) cm2/sec. Sixteen percent of the multivalent and 50% of the paucivalent probes had values for D in excess of 0.6 x 10(-8) cm2/sec, which, after allowance for stochastic variation, are consistent with the D of 1.3 x 10(-8) cm2/sec measured by fluorescence recovery after photobleaching of Fl-PtdEtn in the planar bilayer. The effect of valency on diffusion suggests that the multivalent gold binds several lipids forming a disk up to 30-40 nm in diameter, resulting in reduced diffusion with respect to the paucivalent gold, which binds one or a very few lipids. Provided the valency of the gold probe is considered in the interpretation of the results. Nanovid microscopy is a valid method for analyzing the movements of single or small groups of molecules within membranes.

Antibodies, Monoclonal↗
PubMed1991

Retrograde neuronal labeling of motoneurons in the rat by fluorescent tracers, and quantitative analysis of oxidative enzyme activity in labeled neurons.

Extensor digitorum longus motoneurons in the rat spinal cord were identified by retrograde labeling with two fluorescent tracers, Fast blue (FB) and Nuclear yellow (NY). Labeled motoneurons had a blue fluorescent cytoplasm at 360 nm excitation wavelength with FB, and a golden-yellow fluorescent nucleus with NY on the cryostat section. Labeled motoneurons were further examined for succinate dehydrogenase activity on the same section used for identification of the motoneurons. This study demonstrates that fluorescent dyes are useful for neuroanatomical studies by the retrograde axonal transport method, and that quantitative analysis of metabolic activity in labeled motoneurons is also possible.

Amidines↗