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E Ito

Publications and source records attributed to E Ito.

At least 19 recordsLinked to original sources
PubMed1992

Long-term transformation of an inhibitory into an excitatory GABAergic synaptic response.

For a constant membrane potential, a predominantly inhibitory GABAergic synaptic response is shown to undergo long-term transformation into an excitatory response after pairing of exogenous gamma-aminobutyric acid (GABA) with postsynaptic depolarization or pairing of pre- and postsynaptic stimulation. Current- and voltage-clamp experiments suggest that this synaptic transformation is due to a shift from a net increase of conductance to a net decrease of conductance in response to GABA. GABA-induced elevation of intracellular calcium is prolonged after the same stimulus pairing and may, therefore, contribute to this synaptic transformation via Ca(2+)-activated phosphorylation pathways. This synaptic transformation, which does not follow unpaired stimulus presentations, occurs in a neuronal compartment spatially separated from the soma, which also changes during stimulus pairing.

Animals↗
PubMed1992

Effect of extracellular phosphatidylinositol on c-myc gene-expressed human renal cancer cell line.

Effect of exogenously added soybean phosphatidylinositol on c-myc gene expressed and unexpressed human cancer cell lines was investigated. When phosphatidylinositol liposomes were introduced into culture media, viability of c-myc unexpressed cells was reduced, while that of c-myc expressed cells was not. Death of c-myc unexpressed cells by phosphatidylinositol liposomes was found to be caused by abnormally accumulated intracellular Ca2+, and it seemed to be related to reduction of protein kinase C activity.

Calcium↗
PubMed1992

Light and electron microscopic studies of the murine heart after repeated administrations of ciguatoxin or ciguatoxin-4c.

After repeated ip and oral administrations of ciguatoxin (CTX) and ciguatoxin-4c (CTX-4c), one of the derivatives of CTX, to male ICR mice at a dose of 0.1 microgram/kg for 15 days, resulted in marked swelling of cardiac cells and endothelial lining cells of blood capillaries in the heart was observed. Single doses caused no discernible pathological changes. Damage to the capillaries was followed by prominent effusion of serum and erythrocytes into the interstitial spaces of the myocardium occurred. Swelling of the endothelial lining cells of capillaries caused narrowing of the lumen and accumulation of blood platelets in capillaries, which resulted in multiple single cell necroses of cardiac muscle cells. Within 1 month after the treatments of these phycotoxins, myocytes and capillaries appeared to be normal. Effusion in the interstitial spaces resulted in formation of bundles of dense collagen, which persisted for 14 months. Diffuse interstitial fibrosis was prominent in septum and ventricles, accompanied by bilateral ventricular hypertrophy. A single dose of 0.7 micrograms/kg ip resulted in severe acute heart injuries, followed by diffuse myocardial fibrosis.

Animals↗
PubMed1992

Light and electron microscopic studies on experimental nocardia-toxicosis in mice.

An exotoxin (HS-6) produced by Nocardia otitidiscaviarum isolated from certain lesions of cutaneous nocardiosis of a male 82-year-old patient induced severe injuries in the pancreas, liver, stomach, small intestine, heart, thymus and kidney of male ICR mice. Mice given Nocardia-free preparation of HS-6 at a dose of 1 mg/kg of body weight developed several autophagic vacuoles in the pancreas and liver within 20 min after the i.p. injection. Thereafter, the autophagic vacuoles increased in number and size with time. About 24 hr after the administration of HS-6, the liver showed marked accumulation of fat droplets in the cytoplasm of the hepatocytes. Although they contained abundant autophagic vacuoles in the regions of RER, there were no lipomatoses in the acinar cells of the pancreas, those of the chief cells and smooth muscle cells of the stomach, Paneth cells, goblet cells, smooth muscle cells of the small intestine, and plasma cells in the digestive tract. Biochemical examinations revealed that HS-6 had no significant effect on the protein synthesis of reticulocytes. Inoculation of the Nocardia into the mouse peritoneal cavities caused marked granulomatoses in the pancreas, liver and regional lymph nodes, but did not develop autophagic vacuoles in RER regions of these organs.

Aged↗
PubMed1992

Delayed appearance of G-protein coupled signal transduction system in developing cerebellar Purkinje cell dendrites.

To investigate the relation between the function of Ca(2+)-activated K+ channels and phosphoinositide turnover, we have examined the physiological and pharmacological characteristics of ionotropic and metabotropic quisqualate (QA) receptors in rat cerebellar Purkinje cells during development using the slice-patch method combined with Ca2+ imaging. The typical response to QA obtained from a rat on postnatal day (PND) 21 consisted of three components: (1) a fast inactivating inward current, (2) a slow inward current, and (3) a slow outward current. The slow inward current was abolished in Ca(2+)-free medium, while the fast inactivating inward current and the slow outward current remained unaffected. The slow outward current which appeared to be activated via a metabotropic receptor was not observed in the Purkinje cell of PND 7 rat, in which dendrites were poorly developed but its amplitude increased linearly with PND. QA caused significant increases in [Ca2+]i in the fully developed dendritic region of the Purkinje cells even in Ca(2+)-free medium, suggesting a dendritic localization of the metabotropic receptors.

Animals↗
PubMed1992

The role of calcium in prolonged modification of a GABAergic synapse.

Caudal hair cell impulses cause postsynaptic inhibition of ipsilateral type B photoreceptors in the snail Hermissenda. This inhibition is shown to be GABAergic according to a number of criteria. HPLC, mass spectrophotometric, and immunocytochemical techniques demonstrated the presence of GABA in the hair cells and their axons. GABA agonists and antagonists mimic and block the synaptic effect in a manner consistent with endogenous GABAergic transmission. Other properties, including I-V relations, conductance changes and reversal potentials, are comparable for exogenous GABA responses and endogenous effects of the hair cell impulses. This inhibitory synapse has been found to undergo a long-lasting transformation into an excitatory synapse if GABA release is paired with post-synaptic depolarization. GABA, via GABAA and GABAB receptors in the B cell, causes the opening of calcium sensitive chloride and potassium channels that leads to the post-synaptic hyperpolarization. GABA also induces a long-lasting intracellular calcium elevation at the terminal branches of the B cell that greatly outlasts the voltage responses. Synaptic transformation induced by pairings is caused by a decrease in both GABA induced chloride and potassium conductances in the post-synaptic B cell, as well as a significant prolongation of the intracellular calcium accumulation in the B cell's terminal axonal branches.

Animals↗
PubMed1992

An autopsy case of renal cell carcinoma associated with extensive peliosis hepatis.

An autopsy case of renal cell carcinoma with extensive peliosis hepatis is reported. The patient was a 34-year-old female, who had had a left nephrectomy for renal cell carcinoma but died of multiple metastases one year and 4 months after surgery, despite chemotherapy and interferon treatment. At autopsy, the liver was enlarged markedly with multiple metastatic nodules and the non-neoplastic hepatic parenchyma had a spongy appearance, due to diffusely scattered, blood-filled cystic lesions. Histological examination showed the oval to irregular shaped blood-filled spaces were lined by hepatic cell cords and located mainly in the periportal area. In addition, almost all of the sinusoids were dilated and communicated with the cystic blood-filled spaces, which also communicated directly with branches of the portal veins at various levels. Several interlobular portal branches were obstructed. The causative mechanism of peliosis hepatis has yet to be elucidated, although some causative conditions have been proposed. In this case, renal cell carcinoma may have caused the sinusoidal dilatation and the vascular changes in the portal areas, such as obstruction of terminal portal branches, may have contributed to its formation.

Adult↗
PubMed1992

Detection of genomic sequences of respiratory syncytial virus in otitis media with effusion in children.

The reverse transcriptase-polymerase chain reaction and the nested polymerase chain reaction were used for detection of respiratory syncytial virus (RSV) sequences in middle ear effusions collected from children with otitis media. Sequences of RSV were detected in 21 of 34 samples tested. These samples were collected during and/or after natural outbreaks of RSV infection in the community. In those patients from whose nasopharynges RSV was isolated, the viral sequences were highly detectable (75%) in the effusions. These observations suggest RSV as an important factor in the pathogenesis of otitis media with effusion.

Base Sequence↗
PubMed1992

Light and electron microscopic observation of experimental palytoxin poisoning in mice.

The effects of palytoxin on young male ICR mice were compared with the combined effects of palytoxin and ouabain or those of several cations as well as the effects of potassium. The target organs of palytoxin were the heart, kidney, pancreas, small intestine and liver. Pathomorphological changes of the heart induced by palytoxin were similar those of a lethal dose of KC1. However, the KC1-treated animals did not show any changes in the kidney. Mice given ouabain at doses up to 5 mg/kg also showed similar injuries in proximal as well as distal convoluted urinary tubules, while the heart of mice given ouabain at the same doses showed no discernible morphological changes. Ouabain 5 mg/kg did not influence the severity of injuries both in the heart and kidney induced by palytoxin at 4 micrograms/kg. Therefore, it may be assumed that palytoxin poisoning is a symptom-complex of hyperkalemia and causes a profound inhibition of Na+, K(+)-ATPase.

Acrylamides↗
PubMed1991

An approach to imaging of living cell surface topography by scanning tunneling microscopy.

Since a scanning tunneling microscope (STM) was developed, an observation of living cell surface has been one of the final aims in the biological application of STM. By developing a new style of STM which was combined with an optical microscope and with a novel system for the centering of both images, we successfully got the STM images of living cell surface of T24 cells (human bladder cancer cell line) and CHO cells (Chinese hamster ovary fibroblast) cultured on highly oriented pyrolytic graphite under the appropriate condition (V greater than 8.0 V, I less than 0.2 nA). Unexpectedly, the living T24 cell showed a slightly uneven surface with a steep foot slope. The CHO cell showed more rough surface with steeper slope of cell foot. Although the STM system had a fine spatial resolution less than 3 nm, the profile of living cell surface covered with electrolyte was clear only when the scanning area was more than 10 microns square.

Animals↗
PubMed1991

Resistance of Histoplasma capsulatum to killing by human neutrophils. Evasion of oxidative burst and lysosomal-fusion products.

The basis for resistance of yeast form of Histoplasma capsulatum to antifungal activity of human neutrophils was studied. In limiting dilution assays and short term coculture assays human neutrophils were ineffective in killing H. capsulatum whereas Candida albicans was readily killed. By contrast, in a cell free hydrogen peroxide-peroxidase-halide system H. capsulatum was as sensitive to killing as C. albicans. Moreover, lysate of human neutrophils effectively substituted for horse-radish peroxidase in a cell free system for killing H. capsulatum. H. capsulatum elicited significant products of the oxidative burst in human neutrophils as detected by luminol-enhanced chemiluminescence. However, the response was two-fold less (p less than 0.05) than that induced by C. albicans. Transmission electron microscopy studies showed that phagosome-lysosome fusion took place when neutrophils phagocytosed C. albicans or H. capsulatum. Taken together, these findings indicate that, even though H. capsulatum elicits an oxidative burst and phagosome-lysosome fusion within the phagosome, it is capable of evading damage in short term assays.

Cells, Cultured↗
PubMed1991

Light and electron microscopic studies of pathologic changes induced in mice by ciguatoxin poisoning.

Acute poisoning induced by ciguatoxin or ciguatoxin-4c in male ICR mice was examined by light and electron microscopy. Target organs were the heart, medulla of adrenal glands, autonomic nerves and penis. There were no significant differences between the toxicity of ciguatoxin and ciguatoxin-4c. Either i.p. injection or oral administration (0.7 micrograms/kg) resulted in marked swelling and focal necrosis of cardiac muscle cells and effusion into the interstitial space of the heart. Degeneration of cells in the medulla of the adrenal glands was also observed. Continuous erection of the penis was observed in about 15% of the mice suffering from ciguatoxicosis. Although severe diarrhea was brought about by the administration of these phycotoxins, no morphological alterations were seen in the mucosa and muscle layers of the small intestine except in autonomic nerve fibers and synapses. Atropine suppressed the symptoms of diarrhea but had no effect on the injury to the cardiac muscle. Reserpine aggravated the clinical signs and pathological findings. Guanethidine and 5-hydroxy dopamine as well as those undergoing bilateral adrenalectomy had no significant effects on the ciguatoxicosis.

Adrenal Medulla↗
PubMed1991

Developmental assembly of calcium-mobilizing systems for excitatory amino acids in rat cerebellum.

The postnatal development of calcium-mobilizing systems was studied by both microfluorometric imaging analysis of Ca2+ on living rat cerebellar slices and immunohistochemical labeling of phosphatidylinositol 4,5-bisphosphate (PIP2) and inositol 1,4,5-trisphosphate binding protein (IP3BP) in fixed rat cerebellum. Stimulation with quisqualate (QA) or N-methyl-D-aspartate (NMDA) enhanced the Ca2+ level only diffusely on postnatal day (PND) 3, but more discretely on PNDs 7 and 15. On PND 21, QA-induced responses were localized in the molecular layer especially, but not in the granular layer. By contrast, NMDA mobilized Ca2+ prominently in the granular layer, but only weakly in the molecular layer. Localized expression of PIP2 in the molecular layer paralleled QA-induced Ca2+ mobilization, but IP3BP was expressed more diffusely. The present study offers the first direct evidence that PIP2, but not IP3BP, is essential for QA-induced Ca2+ mobilization in the cerebellar cortex.

Amino Acids↗