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K Morimoto

Publications and source records attributed to K Morimoto.

At least 541 records · Page 30Linked to original sources
PubMed1987

Effects of acute and long-term treatment with amphetamine on evoked responses and long-term potentiation in the dentate gyrus of anesthetized rats.

We examined the effects of D-amphetamine (AMP) on evoked responses and long-term potentiation (LTP) in the dentate gyrus of rats in 4 different conditions: untreated + saline, untreated + acute AMP, long-term AMP-treated + saline, and long-term AMP-treated + acute AMP. Long-term AMP-treatment comprised once daily i.p. injections of 5 mg/kg AMP for 14 consecutive days followed by 7 drug-free days. Acute AMP administration consisted of a single i.p. injection of 5 mg/kg. Acute AMP significantly increased the slope of the synaptic component, the excitatory postsynaptic potential (EPSP), of the evoked response without changing the cell discharge component (population spike), resulting in a significant decrease in the population spike per unit EPSP in the evoked potentials of both untreated and long-term AMP-treated rats. The acute AMP slightly reduced LTP of the population spike in the untreated rats and significantly reduced it in the long-term AMP-treated rats. LTP of the EPSP did not differ between the 4 conditions. The two saline conditions did not differ significantly in their evoked responses or in LTP. It is suggested that AMP has 3 acute effects in the dentate gyrus, and that the effect of reducing the capacity for LTP of the population spike is selectively enhanced following long-term AMP treatment.

Animals↗
PubMed1987

Pathology of brain parenchyma in meningeal carcinomatosis; immunohistochemical study with astroprotein (GFAP) and tubulin.

Effects of leptomeningeal tumor on the brain parenchyma was studied by the immunohistochemical method with astroprotein (GFAP) and tubulin in a rat model of meningeal carcinomatosis. Thickening of subpial glial lining (external glial layer) and hypertrophy of subpial astrocytes, detected by the antiserum to GFAP, was the early sign of parenchymal involvement. The glial lining was continuous as far as the tumor cells were confined to the subarachnoid space, however, penetration of tumor cells into subpial brain was associated with disruption of the glial lining. Speculative role of this lining in preventing the tumor cell to infiltrate into brain tissue was discussed. In contrast to the prominent immunohistochemical changes in astrocytes, neuronal tubulin immunoreactivity was not altered even in the late stage of the disease. The present study demonstrated that the leptomeningeal dissemination of tumor cells did cause pathologic change in brain parenchyma as was evidenced by the reactive change of astrocytes. However, the preserved immunoreaction for tubulin suggested that the nerve cell damage was not severe even at the advanced stage of the disease.

Animals↗
PubMed1987

Kindling-induced changes in the EEG recorded during stimulation from the site of stimulation. II. Comparison between spontaneous and evoked potentials.

We previously described how the EEG activity recorded during kindling-inducing tetanic stimulation, from the site of stimulation, consists of three major components. Here, we investigate the nature and role of component 1, an initial evoked potential, seen at the beginning of tetanus, and we compare it with the potential evoked by single-pulse stimulation and with the spontaneous interictal discharges seen after kindling in both the amygdala and hippocampus. The amplitude of component 1 increased during kindling, and the waveform, latency, and stimulus-response curve of component 1 were all similar to those of potentials evoked by single-pulse stimulation. Furthermore, in acute experiments, in which the amygdala was kindled by tetanic stimulation at 1-h intervals, the evoked potentials in the amygdala and pyriform cortex were markedly potentiated, whereas no obvious potential was recorded at the same latency from the ventral or dorsal hippocampus, subiculum, nor the prepyriform region. Thus, we conclude that, in the case of amygdala kindling, the nature of component 1 is a local direct and monosynaptic response involving the amygdala and pyriform cortex, and that the increased amplitude of component 1 after kindling may be related to long-term potentiation. Although the single-pulse stimulation produced late burst-like components in the amygdala and hippocampus after kindling, it produced neither EEG suppression, well-formed rhythmic synchronous bursts, nor epileptiform discharge, suggesting that component 1 alone is not sufficient for the subsequent events that may be essential to the seizure-triggering mechanism.

Amygdala↗
PubMed1987

Kindling-induced changes in EEG recorded during stimulation from the site of stimulation. III. Direct pharmacological manipulations of the kindled amygdala.

In our previous studies, we hypothesized that activation and subsequent collapse of GABA-mediated inhibition during tetanus is an important seizure-triggering mechanism in the kindled epileptogenic focus. To examine this hypothesis, in the present study, we investigated the effects of pharmacological manipulations of the kindled amygdala with several drugs, and measured the kindled seizures as well as the EEG events during tetanus. The results obtained were: (i) The selective GABA-A agonist, muscimol (1 and 5 nM/1 microliter), suppressed kindled seizures in a dose-dependent fashion, and the 5 nM muscimol significantly prolonged EEG suppression and reduced the number of oscillations in the subsequent rhythmic synchronous discharge. Similar effects followed systemic injection of diazepam (2 mg/kg). (ii) The selective GABA-B agonist, baclofen (5 nM), had no effect on kindled seizures nor on the EEG events during tetanus. (iii) The NMDA antagonist, 2-amino-5-phosphonovaleric acid (80 nM), significantly reduced the afterdischarge duration and significantly delayed the appearance of the rhythmic synchronous discharge. However, these effects were not observed immediately, but 24 to 72 h after microinjection. (iv) The muscarinic cholinergic antagonist, atropine (40 and 80 nM), suppressed kindled seizures in a dose-dependent fashion, but the atropine caused marked synchronous discharge both in the awake resting EEG and during tetanic stimulation. We conclude that the GABA-A system, including the benzodiazepine system, is more involved in the seizure-triggering mechanism of amygdala kindling than the GABA-B system, that there is an interaction between the GABA-A and NMDA system, and that the cholinergic participation is independent of the primary seizure-triggering mechanisms.

2-Amino-5-phosphonovalerate↗
PubMed1987

Prenatal developmental process of human temporomandibular joint.

The prenatal development of 20 human TMJs from the fourteenth gestational week to full term was studied and the following observations were made. Radiologic findings: at the sixteenth gestational week, the outline of the TMJ as radioopaque structures appeared. Curvature of the articular eminence of the temporal components was observed at gestational week 33, and convexity of the condylar head of the condylar process was observed at the thirty-first week. Histologic findings: at the fifteenth gestational week, thin intramembranous ossification of the temporal components and endochondral ossification of the condylar process were observed, and secondary cartilage occupied the whole condylar process. The articular disk was distinguishable and was composed of fine collagen fibers. At the seventeenth gestational week, endochondral ossification of the condylar process appeared, the formation of joint cavities was fairly completed, and synovial tissues were easily observed. From gestational week 17 through 21, endochondral ossification of the condylar process developed rapidly and the layer structures, which consisted of a fibrous covering layer, transitional cell layer, hypertrophic layer, and erosive layer, were observed. At the twenty-first gestational week, Meckel's cartilage disappeared and hematopoietic foci appeared in the temporal components and the condylar process. Week 21 seemed to be the greatest turning point of the prenatal development of the human TMJ. Secondary cartilage of the condylar process diminished gradually throughout fetal life, but was vestigial at full term.(ABSTRACT TRUNCATED AT 250 WORDS)

Cartilage, Articular↗
PubMed1987

Enhancing effects of cytosine arabinoside on ethyl methanesulfonate-induced 6-thioguanine resistance mutations in Chinese hamster V79 cells.

We studied the synergistic enhancement effects of two chemicals which are different in their mechanism of action on DNA in cells. The test chemicals used were ethyl methanesulfonate (EMS) as an alkylating agent and cytosine arabinoside (Ara-C) as an analogue of cytidine. For determination of mutagenesis we measured the induction of resistance to 6-thioguanine (6-TG) in Chinese hamster V79 cells. EMS had a strong mutagenic effect on V79 cells, but for Ara-C the results were less clear. In this study, Ara-C had no detectable effect in inducing mutation up to a concentration of 5 X 10(-4) M. The mutation frequency of combined treatment with EMS and Ara-C was significantly higher than that obtained with EMS alone. These results indicate that Ara-C had an enhancing effect on mutations induced by EMS.

Animals↗
PubMed1987

Clinico-pathological study on denture stomatitis.

The clinical and pathological study was performed in order to determine the histopathological and cytoimmunological characteristics of denture stomatitis. All specimens were biopsy materials from seventeen patients with denture stomatitis. Normal palatal mucosae from ten patients served as the control. In addition to the usual staining methods, naphtol AS-D chloroacetate esterase stain and peroxidase-antiperoxidase method were used to detect mast cells and plasma cells. Denture stomatitis could be divided into atrophic and hyperplastic types. The former showed a smooth and atrophic mucosa. The latter showed a large number of exophytic projections which were composed of marked acanthosis and submucosal fibrosis, and was further subdivided into granular and papillary subtype according to the size of projections. In the present study, there were six cases of the atrophic type, and eleven cases of the hyperplastic type (consisting of seven granular and four papillary subtypes). The hyperplastic type was more frequently observed in patients with partial dentures compared with complete dentures and was associated frequently with ill fitting of the denture base as well as agglutination of denture plaque. Cytoimmunological study revealed that there was a pronounced increase of plasma cells, especially IgG- and IgA-producing cells, and a moderate increase of lymphocytes as well as mast cells in both types of denture stomatitis. Mast cells were always noted in the area with marked plasma cell infiltration, suggesting an intimate relation between both cells. These findings suggest that the immunological reactions play some role in the pathogenesis of denture stomatitis.

Adolescent↗
PubMed1987

High alkaline phosphatase activity of telangiectatic osteosarcoma (TOS) and its diagnostic significance.

Telangiectatic osteosarcoma (TOS) which occurred in the metaphysis of the right femoral bone in a 13-year-old female was reported. It showed osteolytic and cystic lesion without sclerotic change on roentgenogram and consisted histologically of various sized blood-filled spaces lined by layers of round to oval tumor cells in the thin fibrous septa. In some solid areas, a proliferation of atypical tumor cells with large prominent nucleoli was evident, embedded in the lace-like osteoid tissue. Mitotic cells were easily encountered. A large population of tumor cells revealed high alkaline phosphatase activity as well as 5'-nucleotidase activity, indicative of osteogenic cell origin. Ultrastructurally, they showed osteogenic characteristics of well-developed rough endoplasmic reticula, cytoplasmic microfibrils, and dense bodies, but not for those of endothelial cells. In this report, we suggest that alkaline phosphatase activity in biopsy and surgical specimens is useful for distinguishing TOS from other osteolytic bone tumors, with regard to its ontogenic discussion.

Adolescent↗
PubMed1987

Evaluation of permeability enhancement of hydrophilic compounds and macromolecular compounds by bile salts through rabbit corneas in-vitro.

The effect of bile salts, sodium taurocholate (TC-Na) and sodium taurodeoxycholate (TDC-Na), on the permeability of hydrophilic compounds and macromolecular compounds through the rabbit cornea in-vitro was examined. 6-Carboxyfluorescein and glutathione were used as low molecular weight hydrophilic model compounds and FITC-dextran (mol. wt 4000) and insulin were used as relatively macromolecular model compounds. TC-Na (2 and 10 mM) marginally increased the corneal permeabilities to hydrophilic compounds and macromolecular compounds. TDC-Na (2 and 10 mM) markedly increased the corneal permeabilities of these compounds.

Animals↗
PubMed1987

Pseudotail associated with spinal dysraphism.

A 5-year-old girl had a caudal appendage and her left buttock was larger than the righ buttock. X-ray examination revealed spina bifida and bony defect of sacrum; computed tomography demonstrated the extension of the tumor from subcutaneous tissue to the spinal canal. Histologically, the pseudotail contained lobulated fatty tissue which was consistent with lipoma. It emphasizes the fact that even lesions that are not situated in the median line should be carefully explored before excision.

Animals↗
PubMed1987

Possible mechanisms for the enhancement of rectal absorption of hydrophilic drugs and polypeptides by aqueous polyacrylic acid gel.

The mechanisms of absorption enhancing effect by polyacrylic acid gel were investigated in rats. Polyacrylic acid gel significantly enhanced rectal absorption of phenol red, a hydrophilic compound. The enhanced absorption was concentration dependent in the range of 0.01-0.05% w/v polyacrylic acid in gel. The gel also significantly increased the influx and the net influx on water movement in rat rectum. Further, the histological change in rectal epithelium after administration of the polyacrylic acid gel was examined with transmission electron microscopy. The structural changes, which were removal of the mucus and fenestrations of the intercellular spaces 5 and 10 min after administration of polyacrylic acid gel, were observed. These changes were reversible and returned relatively soon to normal levels. Thus, the absorption promoting effect by polyacrylic acid gel may occur mainly with increased water influx as a driving force.

Acrylic Resins↗