Search PubMed⌕ Search

Biomedical subjects

S Kuroda

Publications and source records attributed to S Kuroda.

At least 271 records · Page 15Linked to original sources
PubMed1995

Long-lasting increase in protein kinase C activity in the hippocampus of amygdala-kindled rat.

Previous studies have demonstrated that membrane-associated protein kinase C (PKC) activities in the right and left hippocampus of rats kindled from the left hippocampus increased significantly at 4 weeks [9] and 4 months [22] after the last seizure compared with those in matched control rats. In this study, we investigated the effect of kindling from the left amygdala on PKC activities in the amygdala/pyriform cortex and hippocampus at long seizure-free intervals (4 and 16 weeks) from the last amygdala-kindled seizure. Membrane-associated PKC activity of the kindled group increased significantly only in the left hippocampus compared with the left side control (the left hippocampus of rats subjected to a sham operation) at 4 weeks (by 34%, P < 0.03) and 16 weeks (by 24%, P < 0.05) after the last seizure. There was no significant alteration in the membrane-associated PKC activity of the kindled group in the right hippocampus or amygdala/pyriform cortex in any seizure-free interval after the last amygdala seizure. Cytosolic PKC activity did not differ between the kindled and control groups in any brain region examined in any seizure-free interval. At 16 weeks after the last seizure, the PKC activity in the P1 fraction of the kindled group increased significantly only in the left hippocampus (by 49%, P < 0.005), but not in the right hippocampus. Neither PKC activity in the P2 fraction nor that in the cytosolic fraction was altered in the kindled group after this seizure-free interval.(ABSTRACT TRUNCATED AT 250 WORDS)

Amygdala↗
PubMed1995

Purification and characterization of REKS from Xenopus eggs. Identification of REKS as a Ras-dependent mitogen-activated protein kinase kinase kinase.

We have previously identified a protein factor, named REKS (Ras-dependent Extracellular signal-regulated kinase/Mitogen-activated protein kinase kinase (MEK) Stimulator), which is necessary for Ras-dependent MEK activation. In this study, we attempted to highly purify and characterize REKS. We have highly purified REKS by successive column chromatographies using a cell-free assay system in which REKS activates recombinant extracellular signal-regulated kinase 2 through recombinant MEK in a guanosine 5'-O-(thiotriphosphate) (GTP gamma S)-Ki-Ras-dependent manner. REKS formed a stable complex with GTP gamma S-Ras; REKS was coimmunoprecipitated with GTP gamma S-Ki-Ras or GTP gamma S-Ha-Ras, but not with GDP-Ki-Ras or GDP-Ha-Ras by an anti-Ras antibody. REKS was absorbed to a GTP gamma S-glutathione S-transferase (GST)-Ha-Ras-coupled glutathione-agarose column but not to a GDP-GST-Ha-Ras-coupled glutathione-agarose column and was coeluted with GTP gamma S-GST-Ha-Ras by reduced glutathione. The minimum molecular mass of REKS was estimated to be about 98 kDa on SDS-polyacrylamide gel electrophoresis. REKS phosphorylated this 98-kDa protein as well as recombinant MEK. REKS was not recognized by any of the anti-c-Raf-1, anti-Mos, and anti-mSte11 antibodies. These results indicate that REKS is a Ras-dependent MEK kinase.

Animals↗
PubMed1995

Cerebral hemodynamics and "re-build-up" phenomenon on electroencephalogram in children with moyamoya disease.

"Re-build-up" phenomenon, induced by hyperventilation, is a characteristic finding on electroencephalogram (EEG) in children with moyamoya disease, and suggests close correlation with cerebral ischemic attack. Its mechanism, however, remains obscure. In this study, we examined the relationship between the cerebral hemodynamics and this phenomenon before and after vascular reconstructive surgery. Regional cerebral blood flow and its reactivity to acetazolamide were analyzed using the xenon-133 inhalation method and single photon emission computed tomography in six children with moyamoya disease. These results were compared with the EEG. Regional vasoreactivity to acetazolamide was significantly lower in "re-build-up" -positive regions than in "re-build-up" -negative regions. Postoperative studies revealed a significant improvement of reactivity in the regions where the "re-build-up" phenomenon disappeared after surgery. These results suggest that the "re-build-up" phenomenon represents a focal reduction of the cerebral perfusion reserve in moyamoya disease.

Acetazolamide↗
PubMed1995

Regional cerebral hemodynamics in childhood moyamoya disease.

Regional cerebral blood flow (rCBF) and its reactivity to acetazolamide were analyzed in a series of 15 cases of childhood moyamoya disease, using the xenon-133 inhalation method and single photon emission CT (SPECT). Most of the patients had normal mean hemispheric cerebral blood flow (mCBF), comparable to that of age-matched healthy children. However, they had abnormal rCBF distribution and disturbed reactivity to acetazolamide in the territory of the internal carotid artery, especially in the frontal lobe. Surgical revascularization for the anterior circulation, which consisted of STA-MCA anastomosis and indirect synangiosis, dramatically improved these cerebral hemodynamics in the anterior circulation, including the frontal lobe, and reactivity to acetazolamide in the whole brain. These results suggest that surgical revascularization for the anterior circulation should be carried out in order to improve cerebral hemodynamics as widely as possible, especially in the frontal lobe, and may improve cerebral perfusion reserve in the posterior circulation.

Acetazolamide↗
PubMed1995

Ontogeny of behavioral sensitization to cocaine.

The ontogeny of the behavioral effects of acute cocaine administration and behavioral sensitization to cocaine in rat pups was investigated. Acute behavior stimulating effects of cocaine were observed in pups as young as 7 postnatal days (PND) old, although they needed a higher dose of cocaine than adult rats to evoke the same motor effects. An adult dose-response curve pattern of stereotypy and locomotion to acute cocaine treatment was observed at PND 21, and of rearing at PND 28. Rats aged PND 7, 14, 21, 28, and 56 received repeated injections of saline or cocaine (15 mg/kg) twice a day for 5 consecutive days. After a 3-week period of abstinence, sensitization to a challenge dose of cocaine was assessed. Cocaine-induced stereotyped behavior was enhanced significantly only in rats in which cocaine pretreatment was initiated on PND 21, 28, and 56, but not earlier on PND 7 and 14. Adult female rats given repeated cocaine injections on PND 56-60 showed significantly greater sensitization than males, but no such sex difference was observed in pups given cocaine repeatedly on PND 21-25 or 28-32. These results show clearly that cocaine-induced behavioral sensitization in rats occurred only when subchronic cocaine administration was commenced on PND 21 or later.

Animals↗
PubMed1995

Sustained increase of methylguanidine in rats after amygdala or hippocampal kindling.

Methylguanidine (MG) and guanidinoacetic acid (GAA) are known to be endogenous convulsants in the mammalian brain. We have reported previously that MG and GAA concentrations were significantly elevated bilaterally in the amygdala (AM) 7 and 28 days after completion of AM kindling. In the present study, we investigated regional changes in MG and GAA in (1) AM-kindled rat brain 3 months after completion of kindling and (2) hippocampal (HIPP)-kindled rat brain 7 and 28 days after completion of kindling, using high-performance liquid chromatography. MG was increased significantly in the kindled AM 3 months after completion of AM kindling (76%, P < 0.05). Significant increases in MG levels were also found 7 and 28 days after completion of HIPP kindling (124%, P < 0.025 and 110%, P < 0.05, respectively) in the left AM, ipsilateral to the kindled site. GAA increased significantly (93%, P < 0.025) only in the left AM, ipsilateral to the kindled site, 7 days after completion of HIPP kindling. These results, together with our previous data, indicate that long-lasting increases of MG occur in the AM regardless of kindled foci, and may be important in producing neuronal hyperexcitability in kindled epileptogenesis.

Amygdala↗
PubMed1995

Characterization of Pseudomonas paucimobilis FP2001 which forms flagella depending upon the presence of rhamnose in liquid medium.

A bacterial strain FP2001 isolated from the exudate of land reclaimed for municipal waste was identified as Pseudomonas paucimobilis. Cells of strain FP2001 were mobile by means of polar monotrichous flagellum, only when rhamnose was added as a carbon source in the liquid medium. The replacement of rhamnose by arabinose, galactose, glucose or xylose did not lead to the formation of flagella.

Bacteriological Techniques↗
PubMed1995

Levodopa induces AP-1 and CREB DNA-binding activities in the rat striatum.

In order to elucidate the effect of levodopa and bromocriptine on the DNA-binding activities of transcription factors, AP-1 and CREB DNA-binding activities were investigated using gel-shift assay. Intraperitoneal administration of 100 mg/kg levodopa with 50 mg/kg benserazide in rats increased both AP-1 and CREB DNA-binding activities in the dorsolateral aspect of the striatum. The major proteins composing the increased AP-1 were JunB and JunD. Bromocriptine at doses of 2.5 and 5.0 mg/kg, however, did not increase these binding activities. Present results suggest that levodopa but not bromocriptine induces these transcription-regulating proteins in the striatum with normal dopaminergic functioning.

Animals↗
PubMed1995

Intracranial pheochromocytoma--a case of noradrenaline-secreting glomus jugulare tumor.

A 43-year-old female was admitted for a labile hypertension and depression. High levels of plasma and urinary noradrenaline strongly suggested a pheochromocytoma. However, clinical investigations revealed a normal adrenal gland and thoraco-abdominal region. Venous samples from multiple sites indicated and increase in noradrenaline in the left jugular vein. Using computed tomography and Gadolinium DTPA (diethylene triamine pentaacetic acid)-enhanced dynamic MR (magnetic resonance) imaging, a tumor was discovered in the cerebello-pontine angle. Carotid angiography showed the feeder arteries clearly. Therefore, the tumor was classified as a noradrenaline-secreting glomus jugulare tumor fed by the carotid artery. After embolization and subsequent medical therapy, blood pressure was well controlled. Twenty cases of intracranial pheochromocytoma have been reported to date. This is the second such case in Japan.

Adult↗
PubMed1995

Evidence for an increased intracellular free calcium concentration in platelets of bronchial asthma patients.

The pathogenesis of bronchial asthma is not yet fully understood. Recently much attention has been given to the hypothesis that intracellular free calcium ([Ca2+]i) metabolism is abnormal in various diseases. In this study we investigated whether [Ca2+]i exists abnormally in subjects with bronchial asthma. The [Ca2+]i in 32 treated or untreated subjects with bronchial asthma were compared with 63 normal subjects. Resting levels of [Ca2+]i were estimated by loading the fluorescent indicator Fura-2 in washed platelets. The [Ca2+]i level in the control subjects was 129.7 +/- 18.0 nM (mean +/- SD). However, in that of the bronchial asthma patients was 152.7 +/- 44.1 nM, significantly higher than that of the control subjects (p < 0.05). It is well recognized that an increase of [Ca2+]i in vascular smooth muscle involves contraction. The findings suggest that the same phenomenon is quite possible in the tracheal smooth muscle and that it plays an important role in the pathogenesis of bronchial asthma.

Adult↗
PubMed1995

Effect of iron as a new type of phosphate binder in hemodialysis patients.

Hyperphosphatemia is one of the major problems requiring management in the majority of hemodialysis patients and they require phosphate-binding agents to control the hyperphosphatemia. Aluminum hydroxide and calcium compounds are used currently as phosphate-binding agents to treat hyperphosphatemia, but these compounds can cause undesirable side effects. Therefore, the development of new phosphate-binding agents is imperative. It is well known that oral and intravenous administration of iron causes hypophosphatemia. We hypothesized that this side effect of iron may be beneficial for the treatment of hyperphosphatemia in hemodialysis patients. Consequently, we conducted a fundamental and clinical investigation of the effects of iron administration. Membrane permeability of phosphorus in a mixture of sodium ferrous citrate and dessicated aluminium hydroxide in the presence of hydrogenated lecithin as a phosporic compound was examined. Fifteen patients undergoing hemodialysis were treated with 150 mg of sodium ferrous citrate given orally for eight weeks. The permeability of the filtering membrane to phosphorus decreased in accordance with the dosage of sodium ferrous citrate and dessicated aluminum hydroxide. The degree of phosphate-binding effect of sodium ferrous citrate was larger than that of dessicated aluminum hydroxide. Serum phosphorus decreased significantly during the experiment. These results suggest that the oral administration of sodium ferrous citrate as a new phosphate binder is a useful therapeutic method for hemodialysis in patients with hyperphosphatemia.

Administration, Oral↗
PubMed1995

[Near-infrared monitoring of cerebral oxygenation during cerebral ischemia].

The objective of this study was to assess the relationship between the changes in the redox state of cytochrome oxidase (Cyt. ox.) and those of spontaneous EEG activity and cellular energy state during cerebral ischemia and recirculation. We induced 5-min forebrain ischemia by occluding the bilateral common carotid arteries in anesthetized gerbils. Redox changes of Cyt. ox. were monitored with near-infrared spectroscopy (NIRS) through the experiments. Cortical energy metabolites, ATP, ADP, and AMP, were also measured with high performance liquid chromatography (HPLC) during ischemia and recirculation. Ischemia immediately caused a rapid reduction of Cyt. ox., which paralleled to deterioration of spontaneous EEG activity and preceded significant changes in cellular energy state. Re-oxygenation of Cyt. ox. was observed just after recirculation, and paralleled to the recovery of cellular energy state. Spontaneous EEG activity did not recover even when all other NIRS parameters almost recovered during recirculation after 5-min ischemia. During clamping of the carotid artery, NIRS findings also correlated with those of somatosensory evoked potential (SEP). We concluded that, by means of monitoring redox changes of Cyt. ox., NIRS can detect non-invasively critical neuronal hypoxia prior to a significant impariment of cellular energy state caused by cerebral ischemia, and that NIRS can also detect recovery of oxidative phosphorylation during recirculation, which cannot be observed on EEG.

Animals↗
PubMed1995

[A long-term hemodialysis patient with spontaneous deep vein thrombosis, showing high levels of coagulo-fibrinolytic markers].

A 70-year-old woman on maintenance hemodialysis for 3 years was admitted to our hospital because of deep vein thrombosis (DVT) in the right femoral vein. Seven days before admission, she suddenly noticed severe pain in her right inguinal region while she was walking on the street. A wide range of stenosis from the iliac to the distal femoral region was detected by both CT scanning and venography. Her hematocrit reading was 30% and her serum erythropoietin level was 10.5 MU/ml, which was within the normal range, on the day of admission. The results of routine coagulation tests, including prothrombin time, activated partial thrombin time and plasma fibrinogen values, were normal. Plasma anti-thrombin III and plasminogen were also normal. In contrast, beta-thromboglobulin, platelet factor IV, fibrinogen degradation product, D-dimer, thrombin-antithrombin III complex (TAT) and fibrinopeptide A were abnormally elevated. In the venous occlusion test which was performed in the forearm of the opposite side of the arterio-venous shunt, plasma tissue type plas-minogen activator values showed little response to occlusion indicating that the vessel endothelium may have been partially damaged. These data suggest that the DVT had been induced by imbalance of increased blood coagulation and decreased fibrinolytic activity. Damaged vascular wall may also have contributed to the production of DVT. Furthermore, it is surprising that the patient had elevated values of D-dimer and TAT for many years without recurrence of the DVT. Spontaneous DVT in an apparently healthy individual on maintenance hemodialysis seems to be rare, compared with arterial thrombosis.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1995

[Surgical effects of trabeculotomy after long-term topical antiglaucoma medications].

We retrospectively analyzed the effects of long-term topical antiglaucoma therapy on the results of trabeculotomy. We studied 83 eyes with 76 primary open angle glaucoma and 7 eyes with capsular glaucoma, each of which had undergone trabeculotomy alone and none of which had a history of laser trabeculoplasty or glaucoma surgery. The outcome of trabeculotomy was assessed after a minimum follow-up of 12 months. Using a life-table method, there was no significant difference in the outcome of trabeculotomy between groups divided by duration and type of preoperative topical therapy. There was not statistically significant difference in the intraocular pressure reduction between the groups of long or short duration of topical therapy. We concluded that the duration and type of topical antiglaucoma medications had no significant effect on the outcome of trabeculotomy.

Administration, Topical↗
PubMed1995

[Surgical treatment for syringomyelia associated with Chiari malformation].

Two major surgical procedures, i.e., foramen magnum decompression (FMD) and syringo-subarachnoid shunt (S-S shunt) have been performed as the treatment for syringomyelia with Chiari malformation in our department. FMD was done principally in patients with symptoms due to Chiari malformation and for small size or localized syrinx, and S-S shunt was applied to patients with main symptoms due to syringomyelia, especially with local pain and for large syrinx in size. Eighty patients of syringomyelia with Chiari malformation were surgically treated. FMD was performed in 38 patients, and S-S shunt in 39 patients as the first operation. FMD were done with craniectomy of posterior fossa, C1 laminectomy and resection of epidural band, but without opening dura, and S-S shunt were done with hemipartial laminectomy and DREZtomy. The clinical outcome was evaluated, comparing the two major surgical procedures. Satisfactory neurological improvement was obtained in the two groups, but S-S shunt group took better improvement than FMD group. These results suggest that both procedures are effective, but should be selected by preoperative clinical and radiological findings.

Adolescent↗