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Biomedical subjects

H Yokoo

Publications and source records attributed to H Yokoo.

At least 55 records · Page 3Linked to original sources
PubMed1998

NMDA- and MK801-induced changes in dopamine release are attenuated in kainic acid-lesioned nucleus accumbens of conscious rats: an in vivo microdialysis study.

Local application of N-methyl-d-aspartate (NMDA) and a NMDA receptor antagonist, MK801 through the dialysis membrane into the nucleus accumbens (NAC) caused a significant decrease and increase in extracellular dopamine (DA) in the NAC of conscious rats, respectively. These neurochemical changes were significantly smaller in the kainic acid (KA)-lesioned NAC than in the intact NAC. These findings show that locally applied NMDA and MK801 into the NAC modulate DA release mainly through indirect mechanism involving putative GABA neuron of the NAC.

Animals↗
PubMed1998

Selective inhibition by riluzole of voltage-dependent sodium channels and catecholamine secretion in adrenal chromaffin cells.

We examined the effects of riluzole, a neuroprotective drug, on voltage-dependent Na channels, nicotinic receptors, and voltage-dependent Ca channels, as well as catecholamine secretion, in comparison with those of verapamil and nicardipine, in primary cultures of bovine adrenal chromaffin cells. Riluzole inhibited veratridine-induced 22Na influx via voltage-dependent Na channels even in the presence of ouabain, an inhibitor of Na,K-ATPase. Blockade of Na channels by riluzole was concentration-dependent with an IC50 of 5.3 microM. It was associated with a similar concentration-related reduction of veratridine-induced 45Ca influx via voltage-dependent Ca channels, and of catecholamine secretion. Riluzole had no effect on 45Ca influx caused by high K, which directly activates voltage-dependent Ca channels, and on nicotine-induced 22Na influx, which passes through the nicotinic receptors. Verapamil and nicardipine attenuated 22Na influx caused by veratridine or nicotine at the same concentrations as they suppressed high K-induced 45Ca influx. The inhibitory effect of riluzole on veratridine-induced 22Na influx disappeared at high concentrations of veratridine. A potentiation of veratridine (site 2 toxin)-induced 22Na influx caused by alpha-scorpion venom (site 3 toxin), beta-scorpion venom (site 4 toxin), or brevetoxin PbTx-3 (site 5 toxin), occurred in the presence of riluzole in the same manner as in control cells. These results suggest that riluzole binds to the veratridine site in voltage-dependent Na channels. It does not impair the cooperative interaction between the functional peptide segments of Na channels, but selectively inhibits gating of Na channels, thereby reducing Ca influx via Ca channels and catecholamine secretion. In contrast, verapamil and nicardipine suppress Na influx both Na channels and nicotinic receptors.

Animals↗
PubMed1998

Expression of aggression attenuates both stress-induced gastric ulcer formation and increases in noradrenaline release in the rat amygdala assessed by intracerebral microdialysis.

The effects of an aggressive biting response on stress-induced noradrenaline (NA) release in the rat amygdala and gastric ulcer formation were studied with an intracerebral microdialysis technique. Rats were exposed to a 60-min period of cold restraint stress with or without being allowed to bite a wooden stick. They were sacrificed 100 min after release from stress to investigate gastric ulcer formation. Cold-restraint stress increased NA release to 304 +/- 22.3 and 206 +/- 23.8% of basal levels (mean +/- SEM) in the nonbiting and biting groups, respectively. The stress-induced increases in NA release in the nonbiting group were significantly higher than those in the biting group. In the nonbiting group, significant increases in NA release continued for 80 min after release from stress; however, NA levels in the biting group recovered to basal levels immediately after the cessation of stress. Although many severe gastric lesions with bleeding were found in the nonbiting group, fewer gastric lesions without bleeding were found in the biting group. The cumulative length of gastric lesions in the nonbiting group and in the biting group was 26.2 +/- 7.4 and 6.8 +/- 3.9 mm (mean +/- SEM), respectively. The mean number of ulcers in the nonbiting group and the biting group was 11.8 +/- 1.3 and 1.8 +/- 0.7 (mean +/- SEM), respectively. Both the cumulative length of ulcers and the number of ulcers were significantly lower than those seen in the nonbiting group. These findings strongly suggest that expression of aggression during stress exposure attenuates not only stress-induced increases in NA release in the rat amygdala but also gastric ulcer formation consequent to stress.

Aggression↗
PubMed1998

Retroperitoneal leiomyosarcoma of a male centenarian.

An autopsy case of retroperitoneal leiomyosarcoma of a centenarial male is described. He complained of abdominal pain in his left side 1 month before his death. Ultrasonography and computed tomography revealed a large mass in the left abdominal cavity. At autopsy, a circumscribed mass, 15 cm in diameter, was found in the left-upper abdominal cavity, and seemed to be derived from the retroperitoneum in an exophytic manner. Histologically, spindle cells with slight eosinophilic cytoplasm and blunt-ended nuclei showed interwoven fascicular growth, and mitotic figures were easily encountered. Immunohistochemically, the tumor cells were labeled by alpha-smooth muscle actin and vimentin. To our knowledge, this case of leiomyosarcoma has presented in the oldest patient ever reported. The rarity of soft tissue sarcomas in the extremely elderly is also discussed.

Aged↗
PubMed1998

Primary localized amyloid tumor of the breast with osseous metaplasia.

A case of primary localized amyloid tumor of the breast is described. It is an extremely rare condition and has not been seen in literature in Japan. A 76-year-old woman visited a hospital because of a painless, hard mass of the right breast. A relatively well demarcated, calcified mass was excised under clinical diagnosis of fibroadenoma. Histologically, massive eosinophilic amorphous material was deposited in breast stroma. It was stained red-orange by Congo red and displayed apple-green birefringence under polarized light. The staining persisted after incubation with KMnO4 and immunolabeling by immunoglobulin chi-light chain antiserum, consistent with the amyloid of AL (Achi) type. Osseous metaplasia with bone marrow cavity, foreign body type giant cells in response to amyloid, and scattered plasma cell infiltration were also recognized. Osseous metaplasia in the breast amyloid tumor has been reported in only one case before. To date, the patient has not developed any clinical or laboratory evidence of systemic amyloidosis or multiple myeloma.

Aged↗
PubMed1998

Immunohistochemical characterization of two novel monoclonal antibodies that recognize human perivascular cells of the central nervous system and macrophage subsets.

Two monoclonal antibodies to cells of monocyte/macrophage lineage were established using a human glial cell-rich fraction as the immunogen. The antibodies, named GP-1 and GP-2, were originally found to react with perivascular cells of the central nervous system. They are immunohistochemically applicable on routinely formalin-fixed, paraffin-embedded tissue sections. GP-1 binds to a lysosomal protein, and GP-2 to a carbohydrate epitope of the cell membrane and lysosomes. Among the visceral organs, GP-1 labeled blood monocytes, almost all kinds of tissue and infiltrating macrophages in both normal and diseased states, and renal tubules. GP-1 staining of tissue macrophages tends to be intensified under inflammatory conditions. GP-1 staining also suggested that perivascular cells and macrophages had different ontogeny. GP-2 immunostained monocytes, Kupffer's cells, red pulp macrophages, infiltrating macrophages and reactive microglia, but not alveolar or tingible body macrophages. Besides those macrophages, GP-2 stained mantle zone lymphocytes, some hematopoietic cells, pneumocytes and renal collecting ducts. The staining pattern of ligands on THP-1 and HL-60 neoplastic human macrophage cell lines was dissimilar to that of other macrophage markers, suggesting that they recognize unknown macrophage-related antigens.

Adult↗
PubMed1997

Recovery from activity-stress ulcer by ad lib feeding in rats.

In order to investigate the recovery from activity-stress ulcers by ad lib-feeding and/or cessation of running, male Wistar rats were exposed to the activity-stress paradigm, and the rats that revealed hypothermia (their rectal temperature fell below 36 degrees C) were sacrificed either immediately or after several 24 h periods of healing. Rats that were sacrificed immediately after the appearance of hypothermia and those that were exposed to restricted feeding plus cessation of running revealed severe activity-stress ulcers, whereas few ulcers were observed in rats given ad lib-feeding and those that were given ad lib-feeding plus cessation of running. Although no significant differences in relative weights of spleen and thymus were obtained among the different recovery conditions, the relative weights of the adrenal glands were highest in the restricted feeding plus cessation of running group, whereas, the other animals exposed to the activity-stress paradigm showed no differences. These results indicate that activity-stress ulcers recover under conditions of ad lib-feeding within 24 h, but they are not influenced by cessation of running. These data also suggest that organ weights are not affected by any manipulations employed in the present study.

Animals↗
PubMed1997

Effect of aging on psychological stress-induced increases in noradrenaline release in the rat anterior hypothalamus: an in vivo microdialysis study.

Basal and psychological stress-induced noradrenaline (NA) release were studied by intracerebral microdialysis in the hypothalamus of rats aged 9 weeks or 12 months. Basal NA output was not significantly different between young (9-week-old; 2.11 +/- 0.22 pg/20 min) and aged (12-month-old; 2.29 +/- 0.34 pg/20 min) rats. Psychological stress for 20 min significantly increased NA release in both groups (186% and 142% of baseline at 9 weeks old and 12 months old, respectively); however, the increase in aged rats was significantly lower than that in young rats (P < 0.01). This finding suggest that the noradrenergic neuronal response to psychological stress is attenuated in aged rats.

Aging↗
PubMed1997

Local muscimol disinhibits mesolimbic dopaminergic activity as examined by brain microdialysis and Fos immunohistochemistry.

Infusion of muscimol (5 X 10[-5] M, 60 min) into the nucleus accumbens (NAC) through a dialysis membrane caused a significant increase in extracellular dopamine (DA) and its metabolite, 3,4-dihydroxyphenylacetic acid (DOPAC). Fos-like immunoreactivity induced by intra-NAC infusion of muscimol was seen ipsilaterally in many accumbofugal target areas, but no Fos-positive neurons were seen in the vicinity of the dialysis membrane in the NAC. Sequential staining of Fos and tyrosine hydroxylase (TH) immunoreactivities revealed that a portion of A10 dopaminergic neurons were double-labelled. These results suggest that muscimol in the NAC disinhibits mesolimbic DA neuronal activity possibly through activity of the accumbofugal GABA neuron system.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1997

Human choroid plexus is an uniquely involved area of the brain in amyloidosis: a histochemical, immunohistochemical and ultrastructural study.

To better understand the characteristics of amyloid deposition in the choroid plexus, we examined autopsied brain by routine histology, immunohistochemistry, and electron microscopy in three group of patients: primary systemic amyloidosis (n = 7), cerebral amyloid angiopathy (CAA, n = 6), and controls (n = 3). Three of the CAA patients had Alzheimer's disease. Congophilic, birefringent amyloid deposits of the choroid plexus were seen in six of the seven cases of systemic light chain amyloidosis. Immunohistochemistry revealed that the deposited amyloids had reactivity for immunoglobulin light chain and amyloid P component. Accumulation of macrophages labeled with monoclonal antibodies against CD 68 and major histocompatibility complex class II antigens were observed around the massive amyloid deposits. The presence of approximately 10 nm amyloid fibrils along the epithelial basement membrane as well as in the vascular walls was ascertained by electron microscopy. In CAA, Congo red-positive amyloid deposits were consistently present in meningeal blood vessels and were often found in senile plaques of the cerebral parenchyma; congophilic amyloid deposits were absent in the choroid plexus. Choroid plexus epithelial cells exhibited immunostaining for beta amyloid precursor protein (APP) with N-terminal- and C-terminal-specific antibodies; in particular, consistent staining was obtained for the latter antibody. Immunoreactivity for amyloid beta protein (A beta) with monoclonal antibodies (6E10, 4G8) was often found in choroid plexus epithelial cells. These findings suggest that amyloid deposition of the choroid plexus depends on the major component protein in amyloidosis, and that the choroid plexus may produce APP and A beta protein although A beta amyloidosis is not evident in the choroid plexus.

Aged↗
PubMed1997

An unusual variant of ependymoma with extensive tumor cell vacuolization.

We report a case of ependymoma with unusual vacuolar features arising in the left occipital lobe of a 2-year-old child. The tumor was composed of cells with single or multiple cytoplasmic vacuoles and clear cells. Some cells showed a signet ring-like configuration. Clear cells were compactly arranged and showed an oligodendro-glioma-like appearance. In addition, there were cellular ependymoma-like areas including perivascular pseudorosettes. On immunohistochemistry, glial fibrillary acidic protein and vimentin were mainly detected in cytoplasmic processes, and epithelial membrane antigen (EMA) staining showed granular and small vesicular reactivity. Ultrastructural investigation demonstrated intercellular microrosettes with or without cilia and long zonula adherens-type junctions that are typical of ependymoma. Furthermore, many intracytoplasmic lumina (ICL) were observed. Some ICL had microvilli and some did not. The latter varied in size, and may have fused with each other to develop giant ICL which could correspond to the signet ring-like configuration. Small ICL without microvilli had an appearance similar to that of distended endoplasmic reticula. Serial semithin and ultrathin sections revealed that EMA-positive structures were consistent with ICL containing microvilli and intercellular microrosettes. To determine the presence of unusual vacuolated ependymoma, electron microscopical examination was required. However, light microscopy was useful for detecting EMA-positive microvesicular and granular structures.

Child, Preschool↗
PubMed1997

Intracytoplasmic chromophobe inclusion bodies in an anaplastic meningioma.

Intracytoplasmic inclusion bodies are rarely found in meningiomas. A 74-year-old woman had an anaplastic meningioma with intracytoplasmic chromophobe inclusion bodies (CIB) histologically. These CIB were various shapes, e.g. round, teardrop-like, fusiform, horse-shoe-like, crescentic and perinuclear. The size of CIB ranged from 7 to 14 microns and the nuclei of the tumor cells with CIB were often eccentric. Most CIB were immunopositive only for vimentin, staining more intensely than surrounding cytoplasm in a comparative study using adjacent sections stained with hematoxylin-eosin and vimentin. CIB showed loosely textured filamentous structures which were in parallel and entangled arrangements ultrastructurally. The diameter of the filaments was 13-14 nm and they were thicker than normal intermediate filaments. Moreover, these filaments appeared to be studded with granular and fuzzy substances. These findings suggest that CIB are mainly composed of abnormally synthesized and arranged vimentin filaments.

Aged↗
PubMed1997

Up-regulation of sodium channel subunit mRNAs and their cell surface expression by antiepileptic valproic acid: activation of calcium channel and catecholamine secretion in adrenal chromaffin cells.

Treatment of cultured bovine adrenal chromaffin cells with a therapeutic concentration (0.6 mM) of valproic acid (VPA) for > 24 h caused a time-dependent (t1/2 = 74 h) increase in [3H]saxitoxin binding up to 1.4-fold without altering the KD value; it was prevented by the simultaneous treatment with cycloheximide (an inhibitor of protein synthesis). VPA also raised Na+ channel alpha- and beta 1-subunit mRNA levels 1.4- and 1.7-fold at 24 h, and 1.6- and 1.8-fold at 72 h, respectively. Chronic (but not acute) exposure to VPA enhanced 22Na+ influx caused by various concentrations of veratridine 1.4-2.1-fold, even when assayed in the presence of Na+,K(+)-ATPase inhibitor, but did not change the EC50 value of veratridine. Ptychodiscus brevis toxin-3 allosterically potentiated veratridine-induced 22Na+ influx by approximately 2-fold in VPA-treated cells as in nontreated cells. Long-term treatment with VPA augmented veratridine-induced 45Ca2+ influx via voltage-dependent Ca2+ channels and catecholamine secretion, but had no effect on 45Ca2+ influx and catecholamine secretion caused by high K+ (a direct activation of voltage-dependent Ca2+ channels). Chronic treatment with VPA also enhanced nicotine-induced 22Na+ influx via the nicotinic receptor-ion channel complex 1.2-1.4-fold with little change in the EC50 value of nicotine, thereby increasing the nicotine-induced 45Ca2+ influx via voltage-dependent Ca2+ channels and catecholamine secretion. These results suggest that chronic treatment with VPA up-regulates cell surface expression of Na+ channels via the transcription/translation-dependent mechanisms, and probably of nicotinic receptors, thereby resulting in the enhancement of Ca2+ channel gating and catecholamine secretion.

Animals↗
PubMed1997

Antagonistic effects of OPC-14597, a novel antipsychotic drug, on quinpirole- and (-)-sulpiride-induced changes in evoked dopamine release in rat striatal slices.

The effects of a newly synthesized quinolinone derivative, 7-[4-(4-(2,3-dichlorophenyl)-1-piperazinyl) butoxy)-3,4-dihydro-2-(1H)-quinolinone (OPC-14597), a novel antipsychotic drug, on electrically evoked dopamine release in rat striatal slices were investigated. OPC-14597 (0.1-10 microM) had no effect on the dopamine release evoked in the striatal slices. The decrease induced by quinpirole, a dopamine receptor agonist, in evoked dopamine release was attenuated by superfusion with OPC-14597 (1 and 10 microM) which by itself had no effect on evoked dopamine release. The increase induced by (-)-sulpiride, a dopamine receptor antagonist, in evoked dopamine release was, moreover, also attenuated by 1 and 10 microM OPC-14597. These findings indicate that OPC-14597 antagonizes both dopamine agonist- and antagonist-induced changes in evoked dopamine release in striatal slices in rats.

Animals↗
PubMed1996

Thymic hyperplasia in patients with Graves' disease. Identification of thyrotropin receptors in human thymus.

Thymic size and density were studied in 23 untreated patients with Graves' disease and 38 control subjects using computed tomography. Both thymic size and density were higher in untreated patients with Graves' disease than in control subjects in the age-matched group. After treatment with antithyroid drugs, both thymic size and density were significantly reduced, with a concomitant decrease in thyrotropin receptor antibodies. PCR of human thymic cDNA using primers for human thyrotropin receptor amplified a fragment in a size expected for the receptor, and its nucleotide sequence was identical to human thyrotropin receptor cDNA in the thyroid. Northern blot analysis of human thymic poly(A)+ RNA demonstrated the presence of the full length form of thyrotropin receptor mRNA. Western blot analysis of human thymic membrane using anti-thyrotropin receptor peptide antibodies demonstrated a band of 100 kD that was also observed in the thyroid membrane. Immunohistochemistry of thymic tissue using mouse antihuman thyrotropin receptor monoclonal antibodies demonstrated the immunostaining of epithelial cells. These results indicate that thymic hyperplasia is apparently associated with Graves' disease and suggest that thymic thyrotropin receptor may act as an autoantigen that may be involved in the pathophysiology of development of Graves' disease.

Adult↗
PubMed1996

A Case Reprot of Lactating Adenoma of the Breast and Review of the literatures in Japan.

We experienced a rare case of lactating adenoma in the mammary gland of a pregnant woman. A 21-year-old pregnant woman visited our clinic with a chief complaint of left mammary gland tumor. Based on palpation, mammograms and echograms, fibroadenoma or phyllodes tumor was diagnosed and enucleation was performed at the time of biopsy. The histopathological diagnosis was lactating adenoma.

Journal Article↗
PubMed1996

Progression of gastritis to monoclonal B-cell lymphoma with resolution and recurrence following eradication of Helicobacter pylori.

OBJECTIVE: To follow a patient with Helicobacter pylori-associated gastritis by performing serial endoscopic biopsies to observe the histologic progression of the gastritis to a monoclonal B-cell lymphoma with resolution and subsequent recurrence following eradication of H pylori organisms. DESIGN: A case report of a patient followed over 3 years. MAIN OUTCOME MEASURES: Characteristics of the gastric mucosa as determined by histologic and gene rearrangement studies on multiple random biopsies obtained serially before and after the eradication of H pylori organisms. RESULTS: A progression from H pylori-associated gastritis through lymphoid hyperplasia to a monoclonal B-cell lymphoma was observed. With the techniques used, a resolution of the lymphoma was observed on eradication of H pylori organisms, with a subsequent recurrence of the lymphoma 15 months later, despite the absence of H pylori organisms. CONCLUSION: The observations made of this patient support an association between H pylori and the development of a gastric monoclonal B-cell lymphoma. This lesion appears to develop in the setting of gastritis and progresses through lymphoid hyperplasia followed subsequently by the lymphoma. We speculate that this process is initially antigen driven by the organism and may subsequently become autonomous as genetic damage is accumulated, so that eradication of H pylori organisms will lead to regression of the lesion to the degree that there are autonomously proliferating cells present.

Biopsy↗