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Biomedical subjects

K Yagi

Publications and source records attributed to K Yagi.

At least 55 records · Page 3Linked to original sources
PubMed2001

MRI of cortical dysplasia--correlation with pathological findings.

Cortical dysplasia (CD) is the most epileptogenic structural lesion associated with epilepsy and patients with intractable seizures caused by this condition are good surgical candidates. MRI plays an important role in detecting the abnormalities of CD. We clarified the MRI characteristics of CD by comparing imaging and histological findings in 20 patients with intractable seizures who underwent surgical resection. There were 12 males and eight females, mean age at operation was 15 years. MRI was performed at 1.5 tesla; T1-weighted, T2- and proton density-weighted spin-echo and fluid-attenuated inversion-recovery (FLAIR) images were obtained. The lesions were in the frontal lobe in nine cases, temporal in two, occipital in another two, insular in one and multilobar in six. Blurring of the grey/white matter junction was seen in all patients, and T2 prolongation in white matter and/or at the grey/white matter junction in 19. Abnormal signal intensity was more frequent in the white matter or at the grey/white matter junction than in the grey matter. FLAIR images made this abnormal high signal easier to appreciate, and we thought them very useful in this context. In areas of T2 prolongation, we saw dysplastic neurones and/or balloon cells, dysmyelination, and ectopic neuronal clustering histologically; glial proliferation played an important role in prolonging T2.

Adolescent↗
PubMed2001

Isolation of an early neural maker gene abundantly expressed in the nervous system of the ascidian, Halocynthia roretzi.

Ascidian tadpole larvae possess a primitive nervous system, which is a prospective prototype of the chordate nervous system. It is composed of relatively few cells but sufficient for complex larval behavior. Here we report on HrETR-1, a gene zygotically expressed in a large proportion of the developing neural cells of the ascidian, Halocynthia roretzi. HrETR-1 is an early neural marker which can be used for analyzing neural differentiation. HrETR-1 expression intensified in most neural cells of genes isolated to date, in both central and peripheral nervous systems including palps as early as the 110-cell stage. Using this gene as a probe, we characterized neural cells in the nervous system as well as confirming their origins. Also, we recognized three types of peripheral epidermal neurons which presumably correlate to the larval neurons previously reported for another ascidian. Among these, five bilateral neurons located in the anterior region of the trunk appeared to be derived from a8.26 blastomeres.

Amino Acid Sequence↗
PubMed2001

Repression of starch degradation under anaerobic conditions by irregularly high levels of ATP in Chlamydomonas sp. MGA161.

It is generally known that in green algal species the acceleration of starch degradation upon transition from aerobic to anaerobic conditions is a result of the Pasteur effect in glycolysis. However, the acceleration of starch degradation did not occur in cells of Chlamydomonas sp. MGA161. In MGA161 cells, the anaerobic ATP level, which decreased to about half of the aerobic ATP level in cells of Chlamydomonas reinhardtii after fermentation for 2 h, was kept higher than its aerobic ATP level. Gramicidin D, a monovalent cation ionophore, markedly decreased the anaerobic and aerobic ATP levels due to the increase in ATP demand, accompanied by the acceleration of starch degradation in MGA161 cells. Although the anaerobic ATP level of C. reinhardtii cells was partially decreased by gramicidin D, starch degradation did not accelerate markedly when compared with the result in MGA161 cells. Therefore, starch was degraded at nearly the maximum rate in C. reinhardtii cells under anaerobic conditions; in contrast, the high level of ATP in MGA161 cells repressed starch degradation even under anaerobic conditions, resulting in the absence of the Pasteur effect.

Journal Article↗
PubMed2001

Amyloid beta protein activates PKC-delta and induces translocation of myristoylated alanine-rich C kinase substrate (MARCKS) in microglia.

The increased accumulation of activated microglia containing amyloid beta protein (Abeta) around senile plaques is a common pathological feature in subjects with Alzheimer's disease (AD). Much less is known, however, of intracellular signal transduction pathways for microglial activation in response to Abeta. We investigated intracellular signaling in response to Abeta stimulation in primary cultured rat microglia. We found that the kinase activity of PKC-delta but not that of PKC-alpha or -epsilon is increased by stimulation of microglia with Abeta, with a striking tyrosine phosphorylation of PKC-delta. In microglia stimulated with Abeta, tyrosine phosphorylation of PKC-delta was evident at the membrane fraction without an overt translocation of PKC-delta. PKC-delta co-immunoprecipitated with MARCKS from microglia stimulated with Abeta. Abeta induced translocation of MARCKS from the membrane fraction to the cytosolic fraction. Immunocytochemical analysis revealed that phosphorylated MARCKS accumulated in the cytoplasm, particularly at the perinuclear region in microglia treated with Abeta. Taken together with our previous observations that Abeta-induced phosphorylation of MARCKS and chemotaxis of microglia are inhibited by either tyrosine kinase or PKC inhibitors, our results provide evidence that Abeta induces phosphorylation and translocation of MARCKS through the tyrosine kinase-PKC-delta signaling pathway in microglia.

Amyloid beta-Peptides↗
PubMed2001

Distinct distribution of four Ca2+-dependent subtypes of protein kinase C in rat olfactory bulb; definite expression of betaII-subtype in the accessory olfactory bulb.

The localization of four subtypes of Ca2+-dependent protein kinase C (PKC) in the main and accessory olfactory bulb was examined by immunocytochemistry by using specific antibodies against each PKC subtype. In the main olfactory bulb, alpha-PKC was densely localized in a large number of granule cells and in a few tufted cells, and faint immunoreactivity was seen in some periglomerular cells. betaI-PKC was intensely found in periglomerular cells and tufted cells. gamma-PKC immunoreactivity was present in the external plexiform layer, the internal plexiform layer, and the granular layer, but the immunoreactivity was found only in the neuropils. Little, if any, betaII-PKC was seen in the main olfactory bulb. On the other hand, the intense immunoreactivity for betaII-PKC was seen in periglomerular cells of the accessory olfactory bulb. The betaI-PKC and gamma-PKC were also present in periglomerular cells of the accessory olfactory bulb, while alpha-PKC was localized only in granule cells. Double staining study in the accessory olfactory bulb showed that betaII-PKC was present in the GABAergic periglomerular cells, while betaI-PKC localized to the non-GABAergic periglomerular cells; gamma-PKC was expressed in both GABAergic and non-GABAergic cells. These findings suggest that four calcium-dependent subtypes of PKC play different roles in the olfactory bulb and definite expression of betaII-PKC strongly suggested the involvement of this subtype in a specific function in the accessory olfactory bulb.

Animals↗
PubMed2001

Correlation of clinicopathological parameters and biological markers related to apoptosis and proliferative activity with a clinical outcome in squamous cell carcinoma of the larynx treated with concurrent chemoradiotherapy.

OBJECTIVE: This study was designed to determine whether biological markers related to apoptosis or proliferative activity are associated with the clinical outcome in patients with squamous cell carcinoma (SCC) of the larynx treated with concurrent chemoradiotherapy. METHODS: Immunostaining with antibodies specific to p53, bcl-2, bax, and MIB-1 was performed to evaluate expression of these proteins in formalin-fixed, paraffin-embedded specimens of 59 patients treated with concurrent chemoradiotherapy (carboplatin, 100 mg/m2, four to six times every week; total radiation dose of 40-65 Gy over 4-6.5 weeks). RESULTS: Multivariate analysis indicated that nodal status was a significant indicator of overall survival (OS: P = 0.001). Patients with bcl-2 positive tumors had better OS than those with bcl-2 negative tumors in both univariate (P = 0.002) and multivariate analyses (P < 0.001 ). In the univariate analysis, a considerable difference in OS was observed among the expressions of bax (P = 0.077), MIB-1 proteins (P = 0.071). and OS. but the difference was not statistically significant. CONCLUSION: This study indicates that nodal status is the major prognostic tactor in patients with SCC of the larynx treated with concurrent chemoradiotherapy. These results provide useful information for predicting prognosis. Further analysis of biological factors is needed to evaluate the value as predictive markers.

Apoptosis↗
PubMed2001

Clinical study of adenoid cystic carcinoma of the head and neck.

OBJECTIVE: We examined prognostic factors and outcome of the primary treatment in patients with adenoid cystic carcinoma (ACC) of the head and neck. METHODS: Twenty patients with ACC of the head and neck who had been treated in our institution from 1985 to 1998 were enrolled in this study. Disease-specific survival rate was analyzed by the Kaplan-Mejer method, and the log-rank test was applied to compare the survival rates. RESULTS: The overall 5- and 10-year survival rates determined by Kaplan-Meier analysis were 81 and 57%, respectively. Patients with major salivary gland ACC obtained the best 10-year survival rate (83%), while those with paranasal sinus ACC had the worst survival rate (33%). Predominance of the solid component on pathological examination might indicate a worse prognosis. Our study revealed that postoperative radiotherapy could yield better control of the lesion focus. Chemotherapy failed in some patients and was not dramatically effective by itself. CONCLUSIONS: The long-term prognosis of ACC was poor. Long-term follow-up is necessary for better prognosis of patients treated with radical treatment regimens.

Adult↗
PubMed2001

Concurrent chemotherapy and radiotherapy as initial treatment for stage II supraglottic squamous cell carcinoma.

OBJECTIVE: To evaluate the efficacy and safety of concurrent carboplatin (CBDCA) and radiotherapy for laryngeal carcinoma. we investigated survival rates and laryngeal preservation rates in patients with this treatment modality and those with radiation therapy only. METHODS: We underwent chemotherapy with CBDCA and conventional radiotherapy concurrently to 17 patients with untreated stage II (T2NOM0) supraglottic squamous cell carcinoma since November 1990. CBDCA (100 mg/m2) was administered intravenously once a week concurrently with radiotherapy (2.5 Gy/fr, 4 times a week). At the dose of 40 Gy, the results were evaluated, and some of the patients underwent planned surgery and others continued the radiotherapy up to 65 Gy. RESULTS: Overall 5-year survival rate by Kaplan-Meier method was 81.1%. Actual laryngeal preservation rate was 76.0%. Toxicity over grade III was noticed in two patients. Compared with 14 cases of historical controls, which were treated by radiation therapy alone between 1988 and 1990, the cases with concurrent radiotherapy and chemotherapy had statistically significant advantage in overall successful laryngeal preservation rate (P < 0.05), whereas the two groups were not significantly different in the overall 5-year survival rate.

Aged↗
PubMed2001

A study of piriform sinus fistula cases.

We have experienced five cases of piriform sinus fistula for the last 10 years. It is a relatively rare disease, and partly because of poor understanding of the disease, in one case infection had repeatedly recurred without being adequately treated for over 20 years, and in most cases there was a long time lapse before the diagnosis. In another case, it was difficult to image the fistula with contrast medium and fistulectomy was performed without identifying it on imaging. We have applied various devices to those cases where imaging of fistula was difficult, and achieved complete resection of fistula and have not observed recurrences of infection after resection.

Adult↗
PubMed2001

A clinical study on the cervical lymph node metastasis of maxillary sinus carcinoma.

OBJECTIVE: To improve the management of maxillary sinus carcinoma, we retrospectively investigated the significance of cervical lymph node metastasis in our treated cases and discussed how to deal with the cervical lymph node metastasis as a prognostic factor. METHODS: Medical records of 118 patients with maxillary sinus carcinoma diagnosed and treated in our institute from 1982 to 1997 were retrospectively reviewed. Tumors were staged according to UICC classification 1987. The cumulative survival was analyzed by the Kaplan-Meier method. Generally, the patients had undergone preoperative radiotherapy and surgery. We examined the cervical lymph node metastasis detected at the first examination and the subsequent cervical lymph node metastasis in relation to the prognoses. RESULTS: The incidence of cervical lymph node metastasis at the initial diagnosis was 7.9% (n = 9), and that of secondary cervical lymph node metastasis without recurrence at the primary site after the first treatment was 8.3% (n = 9). In most cases, we observed metastasis to the lymph nodes in the submandibular region and in the jugular chain. The result of treatment of cervical lymph node metastasis was grave. Among the patients with cervical lymph node metastasis detected at the first examination, four patients developed local recurrence and three patients developed distant metastasis. On the other hand, among those with secondary cervical metastasis, three patients developed neck recurrence and three patients developed distant metastasis, but no local recurrence. CONCLUSIONS: In the cervical metastasis of maxillary sinus carcinoma, it is important to treat the primary lesion completely. In addition to it. we should control cervical metastasis and careful neck dissection is required. For the patients with cervical lymph node metastasis, it is necessary to consider the further treatment of distant metastasis.

Adult↗
PubMed2001

A rare aneurysmal bone cyst of the maxillary sinus: a case report.

Aneurysmal bone cyst (ABC) is a non-neoplastic expansile bone lesion that is common in the long bones; only 2% occurs in the head and neck. We present a case of ABC in a 23-year-old male and describe the clinical and radiological features, histopathology and treatment. Magnetic resonance imaging (MRI) demonstrated multiple internal septations, cysts with fluid-fluid levels of varying intensity, and an intact rim of low-intensity signal completely surrounding the lesion. The tumor was removed by enucleation with resection of the lateral nasal cavity. Histopathologic diagnosis was ABC and fibrous dysplasia. We suggest that MRI is very useful for the diagnosis of ABC. ABC is thought to follow other lesions, and thus when treating ABC, it is important to determine whether any pre-existing lesion has preceded or not; in particular, if the lesion site is in the head and neck region.

Adult↗
PubMed2001

Long-term follow-up study of West syndrome associated with tuberous sclerosis.

AIM: To analyze the evolution of seizures, electroencephalographic (EEG) features, seizure outcomes, and social outcomes, in order to formulate a basis for the long-term prognosis of West syndrome (WS) associated with tuberous sclerosis (TS). METHOD: The clinical profiles of 50 patients with TS, who presented with WS in infancy and had been monitored for more than 10 years after the initial examination, were analyzed. RESULTS: In 86% of the patients the seizure type did not change throughout the course of this study. However, 14% of patients had developed other types of seizures by the end of the follow-up period. The seizure outcome was unfavorable for patients with generalized seizures. Partial seizures were controlled in nine (64%) of the 14 patients, and normal or slightly subnormal intelligence accounted for seven of the 14 patients. CONCLUSIONS: Therefore, in patients with WS associated with TS, the seizure outcome and social activity depended on the type of seizure that developed during the course of this disorder. The outcome of patients with WS associated with TS seems to be better than that of WS in general.

Electroencephalography↗
PubMed2001

First report of Trichinella nativa in red foxes (Vulpes vulpes schrencki) from Otaru City, Hokkaido, Japan.

Forty-three red foxes (Vulpes vulpes schrencki) and nine raccoon dogs (Nyctereutes procyonoides viverrinus) were captured in Otaru City, Hokkaido, Japan and examined by muscle digestion for the presence of Trichinella sp. larvae. Of the foxes, five (11.6%) were positive for larvae of Trichinella nativa while none of the raccoon dogs were found to be positive. This finding suggests that the red foxes are important reservoir hosts of sylvatic trichinellosis in Otaru, Hokkaido. This is the first report on Trichinella nativa in wild red foxes of Hokkaido, Japan.

Animals↗
PubMed2001

Involvement of N-methyl-D-aspartic acid receptor activation in oxytocin and vasopressin release after osmotic stimuli in rats.

The present study aimed to examine roles of N-methyl-D-aspartic acid (NMDA) receptors in oxytocin and vasopressin release after osmotic stimuli. A noncompetitive NMDA receptor antagonist, MK-801 (0.2 mg/kg body weight, i.p.), significantly decreased plasma concentrations of oxytocin and vasopressin after hypertonic saline injection (0.3 or 0.6 M NaCl, i.p., 20 ml/kg). By contrast, oxytocin release induced by injection of cholecystokinin octapeptide (20 microg/kg, i.p.) was not significantly changed by MK-801. Hypertonic saline injection increased the number of cells expressing Fos in the supraoptic nucleus and in the regions anterior and ventral to the third ventricle (AV3V) regions [the organum vasculosum of the lamina terminalis (OVLT) and median preoptic nucleus]. MK-801 decreased the number of cells expressing protein in these areas after hypertonic saline injection. A microdialysis method showed that a hypertonic saline injection (0.6 M NaCl, 20 ml/kg, i.p.) facilitated glutamic acid release in and near the OVLT. The results support the view that NMDA receptor in the AV3V region modulates in a facilitative fashion the AV3V inputs to the supraoptic neurosecretory neurones.

Animals↗
PubMed2001

Facilitation of Ca2+ store-dependent noradrenaline release after an N-methyl-D-aspartate receptor antagonist in the rat supraoptic nucleus.

We examined the role of N-methyl-d-aspartate (NMDA) receptors in the control of noradrenaline release in the supraoptic nucleus (SON) using a microdialysis method in urethane-anaesthetized rats. Local application of 0.5 mm NMDA into the SON by retrodialysis decreased noradrenaline content in the dialysate from the SON. On the other hand, MK-801, a channel blocker of NMDA receptors, or D(-)2-amino-5-phosphonopentanoic acid (AP-5), a competitive NMDA receptor antagonist, increased the basal noradrenaline content. Tetrodotoxin did not completely block the noradrenaline increase after NMDA antagonists. Infusion of Ca2+-free solution containing Ni2+ and Cd2+, or a mixture of omega-agatoxin IVA and omega-conotoxin GVIA, voltage-sensitive Ca2+ channels blockers, did not block noradrenaline increase after AP-5, but blocked noradrenaline increase after high K+. Infusion of intracellular Ca2+ blockers, thapsigargin or TMB-8, impaired noradrenaline increase after AP-5 but not that after high K+. These data are consistent with the hypothesis that activation of an NMDA receptor inhibits an intracellular Ca2+ store-dependent noradrenaline release from nerve terminals in the SON.

Adrenergic Uptake Inhibitors↗
PubMed2001

Interictal and ictal magnetoencephalographic study in patients with medial frontal lobe epilepsy.

PURPOSE: To determine whether magnetoencephalography (MEG) has any clinical value for the analysis of seizure discharges in patients with medial frontal lobe epilepsy (FLE). METHODS: Four patients were studied with 74-channel MEG. Interictal and ictal electroencephalographic (EEG) and MEG recordings were obtained. The equivalent current dipoles (ECDs) of the MEG spikes were calculated. RESULTS: In two patients with postural seizures, interictal EEG spikes occurred at Cz or Fz. The ECDs of interictal MEG spikes were localized around the supplementary motor area. In the other two patients with focal motor or oculomotor seizures, interictal EEG spikes occurred at Fz or Cz. The ECDs of interictal MEG spikes were localized at the top of the medial frontal region. The ECDs detected at MEG ictal onset were also localized in the same area as those of the interictal discharges. CONCLUSIONS: In medial FLE patients, interictal and ictal MEG indicated consistent ECD localization that corresponded to the semiology of clinical seizures. Our findings demonstrate that MEG is a useful tool for detecting epileptogenic focus.

Adolescent↗
PubMed2001

Manic episode in epilepsy and bipolar I disorder: a comparative analysis of 13 patients.

PURPOSE: To determine whether the manic episode of patients with epilepsy has different characteristics from manic episode of patients with bipolar disorder. METHODS: Interictal manic episodes in patients with epilepsy (epilepsy group) were compared with mood disorders in patients with bipolar I disorder (bipolar group), as defined by the DSM-IV. There were 13 patients (five women and eight men) in each group. RESULTS: Five epilepsy patients had relatives with epilepsy and/or convulsions, and four bipolar patients had relatives with mood disorders. In the epilepsy group, two had substance-related or organic factors associated with the episodes besides epilepsy, and two exhibited a postictal manic state that had the same symptoms as those of their interictal manic episodes. Ten patients of the epilepsy group had dependent-childish behavior. The epilepsy group had fewer severe mood episodes than the bipolar group. Ten epilepsy patients had fluctuating mood disturbances, and eight had rapid cycling of mood episodes. The epileptogenic zone was in the frontal and/or temporal lobes of eight patients and in multiple lobes of two others; it could not be localized in the three remaining patients. CONCLUSIONS: The clinical features of the interictal manic episodes in the epilepsy group were different from those in the bipolar group. The manic episodes of the epilepsy group appeared heterogeneous in their causal factors. An epileptogenic zone in the frontal and temporal lobes seems to play an important role in the mood episodes of the majority of patients with epilepsy.

Adolescent↗