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Biomedical subjects

A Ishihara

Publications and source records attributed to A Ishihara.

At least 127 records · Page 7Linked to original sources
PubMed1994

Postnatal changes in cell body size and oxidative enzyme activity of spinal motoneurons innervating the rat tibialis anterior muscle.

The cell body size and succinate dehydrogenase (SDH) activity of spinal motoneurons innervating the superficial and deep regions of the tibialis anterior muscle were studied in rats ranging in postnatal age from 3 to 11 weeks, by retrograde neuronal labeling using fluorescent neuronal tracers. The motoneurons innervating the tibialis anterior muscle were located primarily at the L4 spinal cord segment and those innervating the superficial and deep regions of the muscle were distributed throughout the entire extent of the motoneuron pool. The distribution of the motoneurons during postnatal development was similar to that observed in the adult animal. The mean cell body size of the motoneurons innervating the superficial region of the muscle in rats from 5 to 11 weeks of age was greater than that innervating the deep region at corresponding ages. The mean SDH activity of the motoneurons innervating the deep region of the muscle increased during postnatal development, while there were no changes in the mean SDH activity of those innervating the superficial region during this period. At 11 weeks of age, the motoneurons innervating the deep region of the muscle had a higher mean SDH activity than those innervating the superficial region. An inverse relationship between cell body size and SDH activity of motoneurons innervating both the superficial and deep regions of the muscle was observed, independent of age. These results indicate that motoneurons innervating the superficial and deep regions of the rat tibialis anterior muscle have different developmental patterns with regard to cell body size and SDH activity.

Aging↗
PubMed1994

Transforming growth factor-beta 1 and -beta 2 promote neurite sprouting and elongation of cultured rat hippocampal neurons.

Transforming growth factor-beta (TGF-beta) is known as a potent regulator of cell proliferation and differentiation. In the present study, we investigated the effects of TGF-beta 1 and -beta 2 on the survival, neurite sprouting and process elongation of primary cultured hippocampal neurons obtained from rat embryos. Addition of TGF-beta 1 little affected the total number of surviving neurons, but clearly increased the number of neurons bearing processes, indicating that TGF-beta 1 promotes neurite sprouting rather than neuronal survival. Furthermore, TGF-beta 1 significantly promoted the elongation of axon-like processes, but did not affect the process branching and the number of dendrite-like processes. TGF-beta 2 also promoted the neurite sprouting and stimulated the elongation of axons without affecting the branching. The effects of TGF-beta 2 were very similar to those of TGF-beta 1 in terms of both effective concentrations (0.1-1 ng/ml) and maximal effects. It is possible that TGF-beta 1 and -beta 2 play roles in the formation of neuritic networks in the central nervous system.

Animals↗
PubMed1994

Effect of altering cerebrospinal fluid pressure on spinal cord blood flow.

Removal of cerebrospinal fluid (CSF) has been proposed as a means of protecting the spinal cord against ischemic injury during thoracoabdominal aneurysm operations. We investigated the effect of altering CSF pressure (CSFP) on lumbar spinal cord blood flow (SCBF) in an experiment using dogs. The SCBF was measured before and after withdrawal of CSF in settings with and without thoracic aortic clamping. Furthermore, SCBF was measured at the basal state and after elevation of CSFP to 20 mm Hg and to 40 mm Hg. The SCBF did not change significantly before and after removal of CSF in settings both with and without thoracic aortic clamping. Elevation of CSFP significantly reduced SCBF. Elevation of CSFP reduces SCBF, but lowering CSFP per se does not increase SCBF whether the thoracic aorta is occluded or not. This supports the notion that removal of CSF offers spinal cord protection only when CSFP is abnormally elevated.

Animals↗
PubMed1994

Hypobaric-hypoxic exposure and histochemical responses of soleus muscle fibers in the rat.

Hypoxia-acclimatized rats had a higher percentage of fast-twitch oxidative glycolytic fibers and a lower percentage of slow-twitch oxidative fibers in the soleus muscle than age-matched normoxic-rats. However, there was no difference in the fiber type composition of the soleus muscle between hypoxic- and normoxic-male rats after hypoxic-rats were bred at the sea level atmospheric pressure for 5 weeks. Therefore, it is suggested that a higher percentage of fast-twitch oxidative glycolytic fibers in the muscle is found only under hypoxic conditions and is due to an acute response to hypoxia.

Animals↗
PubMed1994

Traction forces generated by locomoting keratocytes.

Traction forces produced by moving fibroblasts have been observed as distortions in flexible substrata including wrinkling of thin, silicone rubber films. Traction forces generated by fibroblast lamellae were thought to represent the forces required to move the cell forwards. However, traction forces could not be detected with faster moving cell types such as leukocytes and growth cones (Harris, A. K., D. Stopak, and P. Wild. 1981. Nature (Lond.). 290:249-251). We have developed a new assay in which traction forces produced by rapidly locomoting fish keratocytes can be detected by the two-dimensional displacements of small beads embedded in the plane of an elastic substratum. Traction forces were not detected at the rapidly extending front edge of the cell. Instead the largest traction forces were exerted perpendicular to the left and right cell margins. The maximum traction forces exerted by keratocytes were estimated to be approximately 2 x 10(-8) N. The pattern of traction forces can be related to the locomotion of a single keratocyte in terms of lamellar contractility and area of close cell-substratum contact.

Animals↗
PubMed1994

Parvovirus B19-associated haemophagocytic syndrome with prominent neutrophilia.

We describe a patient with both haemophagocytic syndrome and acute myocarditis probably associated with parvovirus B19 infection. The patient had a marked neutrophilia instead of neutropenia more usually observed in virus-associated haemophagocytic syndrome (VAHS). Endogenous serum concentrations of macrophage colony-stimulating factor (M-CSF), granulocyte colony-stimulating factor (G-CSF), and tumour necrosis factor-alpha (TNF-alpha) were higher than normal, suggesting that these cytokines may be involved in the genesis of the observed syndrome.

Acute Disease↗
PubMed1994

Distribution of substance P immunoreactive nerve fibers in the tracheal submucosal gland of cats.

Immunohistochemistry combined with electron microscopy was employed to investigate the distribution of substance P-immunoreactive (SP-IR) nerve fibers in the tracheal submucosal gland of cats. The SP-IR nerve fibers were found to form a network around the glands. Numerous varicosities were also detected within the basement membrane of the acini and secretory tubules. All the intraglandular varicosities showed close spatial contact with serous cells, mucous cells, and myoepithelial cells. Our findings suggest that substance P-induced mucus secretion from tracheal submucosal glands in cats may be caused not only by a glandular contractile response of myoepithelial cells, but also by direct stimulation to both serous and mucous cells.

Animals↗
PubMed1994

[Autologous pulmonary arterial flap for repair of truncus arteriosus in neonate and small infants].

Complete correction without external conduit repair by autologous pulmonary arterial flap was performed for the truncus arteriosus in one neonate and two small infants. In this study, we investigated advantages of postoperative hemodynamics and pulmonary artery growth from the data on truncus arteriosus repaired by the autologous flap technique. Patient in this study was classified as type I or II truncus arteriosus and age ranged from 19 days to 95 days after birth. One of the patients died of unexpected gastric bleeding 25 days after surgery. However, all showed excellent hemodynamics in the early postoperative period. The reconstructed pulmonary tract positioned rather left ward and posterior to the level of the systemic root than the technique with extra cardiac conduit repair. Compression did not occur at the created pulmonary tract and hemodynamics was fairly stable after closure of the chest. The postoperative RVP/LVP ratio ranged among 0.45 to 0.65 and the pressure gradient across the right ventricular out flow tract demonstrated only 10-15 mmHg. The size of the pulmonary arterial flap was sufficient even in type II truncus arteriosus to create right ventricle-to-pulmonary tract. However, the first patient underwent subsequent surgery 20 months after the initial surgery, because of left pulmonary artery stenosis due to intimal tissue overgrowth distal to the outflow patch. Surgical findings revealed that the posterior wall of the pulmonary tract was smooth and well developed. Traction of pulmonary arterial flap toward the right ventricular outflow tract shortens the distance between monocusp and left pulmonary arterial orifice than expected.(ABSTRACT TRUNCATED AT 250 WORDS)

Humans↗
PubMed1994

[Adult T cell leukemia with cytomegalovirus associated hemophagocytic syndrome].

A 59-year-old woman, diagnosed as adult T-cell leukemia (ATL), was admitted because of fever and disturbance of consciousness. Peripheral blood examination demonstrated leukopenia and anemia, and subsequently thrombocytopenia. Bone marrow aspiration showed the increase of mature histiocytes with hemophagocytosis and a diagnosis of hemophagocytic syndrome (HPS) was established. She died due to respiratory failure on the eighth hospital day. Autopsy histological examination revealed systemic cytomegalovirus (CMV) infection with CMV pneumonia, and also demonstrated the findings of HPS in bone marrow, lymph nodes, and spleen. This case was considered as virus associated hemophagocytic syndrome (VAHS) developed by CMV infection. CMV is one of the causative viruses of VAHS and the opportunistic infection. In the patient with ATL in the immunodeficiency state, VAHS accompanied with opportunistic infection might be one of the causes of pancytopenia.

Cytomegalovirus Infections↗
PubMed1994

[A case of paradoxical cerebral embolism through a patent foramen ovale diagnosed by necropsy].

A 62-year-old man was admitted to our hospital for disturbed consciousness and left-side motor sensory deficit. His blood pressure was 142/100 mmHg and an electrocardiogram was normal. CT of the brain revealed a low density area in the distribution of the right middle cerebral artery (MCA). Cerebral angiography demonstrated occlusion of the right internal carotid artery and an embolus. We diagnosed cerebral embolism, but we could not detect source of embolism. His condition deteriorated rapidly, and he died four days later. At necropsy, an elongated piece of thrombus 10 cm in length was lodged in a patent foramen ovale lying in each atrium. No other thrombus was seen in the heart, the myocardium and coronary arteries were normal. Both main pulmonary arteries contained thrombus. The lungs showed edema and congestion. There was no thrombus of both common iliac veins. The right internal carotid artery was occluded at its bifurcation by embolus, distal to which the cavernous segment was 7 cm filled with clot. We reported a rare paradoxical cerebral embolism through a patent foramen ovale diagnosed by necropsy. If no left-sided circulatory source can be demonstrated, the possibility of a paradoxical embolism should be considered.

Heart Septal Defects, Atrial↗
PubMed1994

[Neurocutaneous melanosis--a case report].

Neurocutaneous melanosis is a rare congenital phacomatosis characterized by the presence of large or multiple congenital melanocytic nevi and benign or malignant pigmented cell tumors of the leptomeninges. A 14-month-old boy was admitted with a recent history of vomiting and drowsiness. He was found to have multiple congenital melanocytic nevi. Gd-enhanced MRI showed ventriculomegaly and leptomeningeal enhancement in the ambient cistern. CSF cytology revealed abnormal cells with pigmented granules. A diagnosis of hydrocephalus with malignant neurocutaneous melanosis was made. The patient was treated with combination chemotherapy (DAV therapy, ACNU intrathecal perfusion therapy, interferon beta therapy) while controlling intracranial pressure by CSF drainage, but in spite of treatment he died due to rapid progression of leptomeningeal infiltration. Postmortem examination revealed meningeal malignant melanomas predominantly at the base of the brain and benign meningeal melanosis over the cerebral cortex. Newborn infants or infants with large or multiple congenital melanocytic nevi should be carefully followed, especially for the first two years. When hydrocephalus or convulsions occur in patients with skin lesions, Cd-enhanced-MRI and careful CSF cytology studies should be performed to detect meningeal abnormalities.

Humans↗
PubMed1994

[Inhibitory effect of running exercise on age-induced muscle atrophy].

The effects of a 10-week running exercise on the histochemical and morphological properties of muscle fibers in the soleus (SOL) and tibialis anterior (TA) muscles and also in spinal motoneurons were investigated in 4 groups of female rats. Animals of the control groups were 20, 90 and 100 weeks old. Animals of the experimental group were 100 weeks old, and were exercised on a running wheel for 10 weeks. Muscle fibers examined were classified as slow-twitch oxidative (SO), fast-twitch oxidative glycolytic (FOG) or fast-twitch glycolytic (FG) according to their contractile and metabolic profiles. Spinal motoneurons innervating the SOL and TA were identified by retrograde neuronal labelling of fluorescent dye, nuclear yellow. Oxidative enzyme activities of motoneurons in the neuron pool were examined by microspectrophotometry. When compared to 20 week old rats, a decrease in the number of FOG in the SOL and of FG in the TA was observed in 90 and 100 week old rats. Findings of atrophy were observed in SO and FOG of the SOL and in FOG and FG of the TA in 90 to 100 week old rats. Practically no changes were observed with aging in the number and oxidative capacity of motoneurons in the SOL neuron pool. However, a decrease with aging was observed in the number and oxidative capacity of motoneurons in the TA neuron pool. From these results it is indicated that exercise inhibits the age-induced atrophy of SO fibers in the SOL.

Aging↗
PubMed1993

Principles of locomotion for simple-shaped cells.

Moving cells display a variety of shapes and modes of locomotion, but it is not clear how motility at the molecular level relates to the locomotion of a whole cell, a problem compounded in studies of cells with complex shapes. A striking feature of fish epidermal keratocyte locomotion is its apparent simplicity. Here we present a kinematic description of locomotion which is consistent with the semicircular shape and persistent 'gliding' motion of fish epidermal keratocytes. We propose that extension of the front and retraction of the rear of these cells occurs perpendicularly to the cell edge, and that a graded distribution of extension and retraction rates along the cell margin maintains cell shape and size during locomotion. Evidence for this description is provided by the predicted circumferential motion of lamellar features and the curvature of 'photo-marked' lines within specific molecular components of moving keratocytes. Our description relates the dynamics of molecular assemblies to the movement of a whole cell.

Animals↗
PubMed1993

Aggressive osteoblastoma of the calcaneus.

Aggressive osteoblastoma of the left calcaneus in 29-year-old Japanese woman is reported. Her initial symptom was heel pain while walking. This was a primary calcaneal tumor, initially diagnosed as a benign osteoblastoma. After a 5-year follow-up (from the initial curettage), there was local recurrence. The histologic findings of aggressive osteoblastoma were confirmed after right lower leg amputation. The recurrent tumor was mildly aggressive to the talocalcanean joint and the retrocalcaneal area, without distant metastasis. The characteristics of the primary and recurrent tumors were examined by the radiologic, histologic, and electron microscopic procedures. Although there are questions about aggressive osteoblastoma, the authors believe that there are osteoblastic tumors of borderline malignancy between benign osteoblastoma and low-grade osteosarcoma. The current case was an example compatible with an aggressive osteoblastoma with the proposed name of Dorfman classification Group 4.

Adult↗
PubMed1993

Fabric heart retractor for coronary artery bypass operations.

A new device for heart retraction during coronary artery bypass operations has been developed. It provides safe and steady support and an unobstructed view of the lateral, posterior, and inferior surfaces of the heart; in addition, it is easy to handle.

Coronary Artery Bypass↗
PubMed1993

How do cells move along surfaces?

The movement of cells along surfaces is a complex phenomenon that consists of several interrelated processes, including cell-substratum adhesion, and extension and retraction of the cell edge, in which the actin cytoskeleton plays a crucial role. The past decade has seen increasingly detailed molecular-based investigations into cell motility, but it is still not known how molecular events are integrated to give cell movement. Molecular studies are now beginning to be linked to a more global concept of how whole cells move, and this combined approach promises to yield new insights into cell locomotion.

Journal Article↗
PubMed1993

Unconfined lateral diffusion and an estimate of pericellular matrix viscosity revealed by measuring the mobility of gold-tagged lipids.

Nanovid (video-enhanced) microscopy was used to determine whether lateral diffusion in the plasma membrane of colloidal gold-tagged lipid molecules is confined or is unrestricted. Confinement could be produced by domains within the plane of the plasma membrane or by filamentous barriers within the pericellular matrix. Fluorescein-phosphatidylethanolamine (F1-PE), incorporated into the plasma membranes of cultured fibroblasts, epithelial cells and keratocytes, was labeled with 30-nm colloidal gold conjugated to anti-fluorescein (anti-F1). The trajectories of the gold-labeled lipids were used to compute diffusion coefficients (DG) and to test for restricted motion. On the cell lamella, the gold-labeled lipids diffused freely in the plasma membrane. Since the gold must move through the pericellular matrix as the attached lipid diffuses in the plasma membrane, this result suggests that any extensive filamentous barriers in the pericellular matrix are at least 40 nm from the plasma membrane surface. The average diffusion coefficients ranged from 1.1 to 1.7 x 10(-9) cm2/s. These values were lower than the average diffusion coefficients (DF) (5.4 to 9.5 x 10(-9) cm2/s) obtained by FRAP. The lower DG is partially due to the pericellular matrix as demonstrated by the result that heparinase treatment of keratocytes significantly increased DG to 2.8 x 10(-9) cm2/s, but did not affect DF. Pericellular matrix viscosity was estimated from the frictional coefficients computed from DG and DF and ranged from 0.5 to 0.9 poise for untreated cells. Heparinase treatment of keratocytes decreased the apparent viscosity to approximately 0.1 poise. To evaluate the presence of domains or barriers, the trajectories and corresponding mean square displacement (MSD) plots of gold-labeled lipids were compared to the trajectories and MSD plots resulting from computer simulations of random walks within corrals. Based on these comparisons, we conclude that, if there are domains limiting the diffusion of F1-PE, most are larger than 5 microns in diameter.

Animals↗