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T Araki

Publications and source records attributed to T Araki.

At least 199 records · Page 11Linked to original sources
PubMed1999

Alteration of neurotensin receptors in MPTP-treated mice.

We examined the sequential changes in neurotensin receptors in the striatum and substantia nigra of mouse brains lesioned with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) by receptor autoradiography, in comparison with the alterations in dopamine uptake sites. The mice received four intraperitoneal injections of MPTP (10 mg/kg) at 1-h intervals and then the brains were analyzed at 6 h and 1, 3, 7, and 21 days after the treatments. [3H]Neurotensin and [3H]mazindol were used to label neurotensin receptors and dopamine uptake sites, respectively. [3H]Neurotensin binding was significantly decreased in the striatum from 6 h to 21 days after MPTP treatment. In the substantia nigra, pars reticulata also showed a significant decrease in [3H]neurotensin binding from 3 to 21 days post-MPTP treatment. However, no significant change in [3H]neurotensin binding was observed in the pars compacta even after 21 days. On the other hand, [3H]mazindol binding was markedly decreased in the striatum and substantia nigra from 6 h to 21 days after MPTP treatment. These results indicate that neurotoxin MPTP can produce a severe decrease in neurotensin receptors and dopamine uptake sites in the striatum and substantia nigra of mice. Thus, our findings provide evidence that the dysfunction in neurotensin receptors may be involved in the degenerative processes causing Parkinson's disease.

1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine↗
PubMed1999

Fast magnetic resonance imaging of liver.

Recent magnetic resonance (MR) units with a stronger gradient system have allowed various fast MR imaging techniques to develop. These fast scan techniques have easily realized breath-holding acquisition in the liver and the image quality has been greatly improved without sacrificing spatial resolution. The majority of the fast imaging techniques have been devoted to T2-weighted imaging to obtain useful T2-weighted images in the shortest possible time. Among the fast sequences, fast spin-echo (FSE) sequence is the most promising technique and allows high-quality T2-weighted images with reduced motion artifacts. However, FSE sequences using multiple refocused pulses may essentially realize only poor soft-tissue contrast due to magnetization transfer and T2-filtering effects, and therefore, echo-planar (EP) imaging is expected to provide high image contrast. In addition, single-shot EP imaging allows even diffusion-weighted (DW) and perfusion-weighted (PW) imaging in the liver due to its short scanning time. Recent development of fast gadolinium-enhanced 3D MR angiography has also impacted liver imaging. Combined with such gadolinium-enhanced 3D-MRA sequences and zerofilling image interpolation technique, biphasic gadolinium-enhanced 3D-MRA (whole-liver dynamic MR imaging in the arterial phase and MR portography in the portal phase) can be obtained.

Contrast Media↗
PubMed1999

Alterations of second messenger systems in the rat brain after 6-hydroxydopamine lesions of the medial forebrain bundle.

We studied the sequential changes in second messenger systems in the striatum and substantia nigra (SN) after 6-hydroxydopamine lesions of the medial forebrain bundle in rats. The animals were unilaterally lesioned in the medial forebrain bundle and the brains were analyzed at 1, 2, 4 and 8 weeks postlesion. [3H]Phorbol-12, 13-dibutyrate (PDBu), [3H]forskolin and [3H]rolipram were used to label protein kinase C (PKC), adenylyl cyclase and calcium/calmodulin-independent cyclic-AMP phosphodiesterase, respectively. The degeneration of nigrostriatal pathway produced a significant increase in [3H]PDBu binding in the ventromedial part of the ipsilateral striatum from 2 to 8 weeks postlesion. In the contralateral side, [3H]PDBu binding showed a transient increase in the SN only 4 weeks after lesioning. [3H]Forskolin binding showed a significant increase in the ipsilateral and contralateral striatum from 2 to 4 weeks postlesion. In the ipsilateral SN, a significant increase in [3H]forskolin binding was observed at 4 weeks after lesioning. However, no significant change in [3H]forskolin binding was observed in the contralateral SN during postlesion. On the other hand, [(3)H]rolipram binding showed no conspicuous alteration in the brain during postlesion. These results demonstrate that rats made hemiparkinsonism by unilateral 6-hydroxydopamine injection have a significant increase in [3H]PDBu and [3H]forskolin binding in the striatum and/or SN, whereas no significant change in [3H]rolipram binding is observed in these areas during postlesion. Our findings also suggest that the increase in [3H]forskolin binding is more pronounced than that in [3H]PDBu binding in the brain after unilateral 6-hydroxydopamine injection. Thus, our studies may provide valuable information concerning degeneration of the nigrostriatal pathway such as Parkinson's disease.

Animals↗
PubMed1999

Increases in [3H]FK-506 and [3H]L-N(G)-nitro-arginine binding in the rat brain after nigrostriatal dopaminergic denervation.

Receptor autoradiographic technique was studied to investigate sequential changes in FK-506 binding proteins, nitric oxide synthase and dopamine uptake sites in the brain 1 week to 8 weeks after unilateral 6-hydroxydopamine injection of the medial forebrain bundle in rats. [3H]FK-506, [3H]L-N(G)-nitro-arginine and [3H]mazindol were used to label FK-506 binding proteins (immunophilin), nitric oxide synthase and dopamine uptake sites, respectively. [3H]FK-506 binding showed about 13-25% increase in the ipsilateral striatum from 2 to 8 weeks after degeneration of nigrostriatal pathway. However, no significant change in [3H]FK-506 binding was observed in the ipsilateral substantia nigra during the postlesion periods. In the contralateral side, [3H]FK-506 binding also showed about 13-25% increase in the striatum from 2 to 8 weeks postlesion. The substantia nigra showed a 21% increase in [3H]FK-506 binding only 2 weeks after the lesioning. On the other hand, [3H]L-N(G)-nitro-arginine binding showed about 21-31% increase in the parietal cortex and striatum 1 week or 2 weeks postlesion. In the contralateral side, a 21% increase in [3H]L-N(G)-nitro-arginine binding was found in the dorsolateral striatum only 1 week postlesion. In contrast, degeneration of nigrostriatal pathway caused a conspicuous loss of [3H]mazindol binding in the ipsilateral striatum (87-96%), substantia nigra (36-73%) and ventral tegmental area (91-100%) during the postlesion periods. In the contralateral side, no significant changes in [3H]mazindol binding were observed in these areas up to 8 weeks after the postlesion. The present study demonstrates that unilateral injection of 6-hydroxydopamine into the medial forebrain bundle of rats can cause a significant increase in [3H]FK-506 and [3H]L-N(G)-nitro-arginine bindings in the brains. In contrast, a marked reduction in [3H]mazindol binding is observed in the brains after the lesioning, indicating severe damage to nigrostriatal dopaminergic pathway. These results suggest that immunophilin and nitric oxide synthase may play some role in the pathogenesis of neurodegenerative disorders such as Parkinson's disease.

Animals↗
PubMed1999

Identification of three kinds of mutually related composite elements conferring S phase-specific transcriptional activation.

Conservation of the Oct motif (CGCGGATC) is a remarkable feature of plant histone gene promoters. Many of the Oct motifs are paired with a distinct motif, Hex, TCA or CCAAT-box, constituting the type I element (CCACGTCANCGATCCGCG), type II element (TCACGCGGATC) and type III element (GATCCGCG-N14-ACCAATCA). To clarify the roles of these Oct-containing composite elements (OCEs) in cell cycle-dependent and tissue-specific expression, we performed gain-of-function experiments with transgenic tobacco cell lines and plants harboring a derivative of the 35S core promoter/beta-glucuronidase fusion gene in which three or four copies of an OCE had been placed upstream. Although their activities were slightly different, results showed that each of the three types of OCEs could confer the ability to direct S phase-specific expression on a heterologous promoter. In transgenic plants, the type I and III elements exhibited a similar activity, directing expression in meristematic tissues, whereas the activity of the type II element appeared to be restricted to young cotyledons and maturating guard cells. Mutational analyses demonstrated that the co-operation of Oct with another module (Hex, TCA or CCAAT-box) was absolutely required for both temporal and spatial regulation. Thus, OCEs play a pivotal role in regulation of the expression of plant histone genes.

Base Sequence↗
PubMed1999

Brain-derived neurotrophic factor stimulates interactions of Shp2 with phosphatidylinositol 3-kinase and Grb2 in cultured cerebral cortical neurons.

Shp2, a protein tyrosine phosphatase possessing SH2 domains, is utilized in the intracellular signaling of various growth factors. Shp2 is highly expressed in the CNS. Brain-derived neurotrophic factor (BDNF), a member of the neurotrophin family, which also shows high levels of expression in the CNS, exerts neurotrophic and neuromodulatory effects in CNS neurons. We examined how BDNF utilizes Shp2 in its signaling pathway in cultured cerebral cortical neurons. We found that BDNF stimulated coprecipitation of several tyrosine-phosphorylated proteins with anti-Shp2 antibody and that Grb2 and phosphatidylinositol 3-kinase (PI3-K) were coprecipitated with anti-Shp2 antibody in response to BDNF. In addition, both anti-Grb2 and anti-PI3-K antibodies coprecipitated Shp2 in response to BDNF. The BDNF-stimulated coprecipitation of the tyrosine-phosphorylated proteins, Grb2, and PI3-K with anti-Shp2 antibody was completely inhibited by K252a, an inhibitor of TrkB receptor tyrosine kinase. This BDNF-stimulated Shp2 signaling was markedly sustained as well as BDNF-induced phosphorylation of TrkB and mitogen-activated protein kinases. In PC12 cells stably expressing TrkB, both BDNF and nerve growth factor stimulated Shp2 signaling similarly to that by BDNF in cultured cortical neurons. These results indicated that Shp2 shows cross-talk with various signaling molecules including Grb2 and PI3-K in BDNF-induced signaling and that Shp2 may be involved in the regulation of various actions of BDNF in CNS neurons.

Adaptor Proteins, Signal Transducing↗
PubMed1999

Functional absence of FADD in PLC/PRF/5 hepatoma cells: possible involvement in the transformation to hepatoma in HBV-infected hepatocytes.

The death receptor Fas transduces apoptotic death signaling upon stimulation by Fas ligand and plays a key role in viral hepatitis. When hepatitis-B virus (HBV) infects hepatocytes, the Fas ligand/Fas system responds as the triggering machinery of hepatitis. However, some HBV-infected cells may circumvent Fas-mediated apoptosis and transform to hepatoma cells, as do PLC/PRF/5 hepatoma cells. Therefore, in the present study, we used PLC/PRF/5 hepatoma cells to investigate this ability to avoid Fas-mediated apoptosis. When the cells were treated with an agonistic Fas antibody, they showed resistance to Fas-mediated apoptosis. In contrast, HepG2 cells of the same hepatoma line succumbed. Caspase 3 and 8, which are essential regulators for Fas-mediated cell death, were expressed in both hepatoma cell lines, but only HepG2 cells showed activation of the caspases. A comparison study of expression of other death-associated factors between PLC/PRF/5 and HepG2 cells revealed no apparent differences. However, Far-Western blotting analysis using the Fas death domain (FDD) showed a significant difference. Molecular weight comparison and immunoblotting analysis revealed that PLC/PRF/5 cells lack the FDD-associated protein FADD. In addition, FDD-injected HepG2 cells showed a resistance to Fas-mediated apoptosis, and PLC/PRF/5 cells acquired Fas-sensitivity by FADD injection. Here, we propose that a functional absence of FADD is one of the pathways for the carcinogenesis of HBV-infected hepatocytes.

Adaptor Proteins, Signal Transducing↗
PubMed1999

Dynamic SPET parameters of 123I-MIBG cardiac imaging.

Early dynamic and late 123I-MIBG SPET studies were performed to investigate several parameters used to distinguish the characteristics of various cardiac disorders. Forty-six individuals (34 non-diabetic, 12 diabetic) with or without heart disease were included in the study. Early dynamic and late static SPET images were acquired using a triple-headed gamma camera. After selecting mid-sections from vertical (VLA) and horizontal (HLA) long-axis images, regions of interest were created over the apex, whole heart and anterior, inferior, septal and lateral walls of the heart. Various uptake ratios at 3, 11 and 19 min and 4 h after injection (HU3, HU11, HU19, DUP) and clearances (Kse: between HU3 and HU11; Ke: between HU11 and HU19; Kd: between HU19 and DUP) were calculated. There were significant differences among various cardiac pathologies on the delayed images. Cardiomyopathy patients showed the lowest uptake on the delayed images. When all segments in normal patients and all involved segments in myocardial infarcted patients were compared, there was significantly lower uptake of MIBG in infarcted segments at all time points. Kd showed the lowest value compared with Kse and Ke. In cardiomyopathy patients, Kse, Ke and Kd were significantly different from each other. Both Kse and Ke were significantly higher in cardiomyopathy patients than in normal patients. In conclusion, the results of this study are in line with published data and precise measurement of uptake and clearance was possible when excluding background and blood pool activity.

3-Iodobenzylguanidine↗
PubMed1999

Conservative management of a case of placenta praevia percreta.

Pregnancies complicated by placenta praevia and a history of caesarean section are associated with increased risk of placenta percreta (1). Placenta praevia percreta sometimes involves the bladder or other pelvic organ, invasion leading to genital bleeding or haematuria (2, 3). Bladder injury or uncontrollable profuse haemorrhage occasionally occurs in such patients during surgery. Examination of placental invasion is necessary as this clinical condition is severe. Treatment of placental myometrium invasion is required to prevent uncontrollable profuse haemorrhage during surgery. We present a multiparous patient who was diagnosed prenatally with placenta praevia percreta using magnetic resonance imaging (MRI) and who was treated conservatively with a good prognosis.

Adult↗
PubMed1999

Photosensitive and nonphotosensitive electronic screen game-induced seizures.

PURPOSE: To disclose possible epileptologic differences between photosensitive and nonphotosensitive patients with seizures induced by electronic screen games (ESGs). METHODS: In patients with ESG-induced seizures who showed photo- and pattern sensitivity, magnetoencephalography (MEG) and EEG were performed simultaneously during ESG play, and equivalent current dipoles (ECDs) of the MEG spikes were estimated. In patients without ESG-induced seizures, who were surgical candidates, the intracranial EEG was analyzed for changes in epileptiform spike frequency. RESULTS: Fifteen of 29 patients were photo- or pattern sensitive, and they had a posterior predominance of ECDs of the MEG spikes. In contrast, nonphotosensitive patients had an anterior predominance of ECDs. Other seizure-precipitating factors in the nonphotosensitive patients included hand manipulation or spatial processing. In patients without a history of ESG-induced seizures who underwent intracranial EEG monitoring for surgical evaluation, ESG playing induced changes in spike frequency in the supplementary motor area, perisylvian region, and medial temporal lobe. CONCLUSIONS: In photosensitive patients, interictal MEG spikes arise predominantly from the posterior region of the brain. In nonphotosensitive patients, epileptiform spikes tend to originate in the anterior part of the brain. Thus factors involving functions of the anterior part of the brain other than photo- or pattern sensitivity may play a role in the induction of seizures during ESG play. Furthermore, the changes in spike frequency in specific brain areas may correspond to their involvement in praxic activity and emotional changes during ESG play. A chance occurrence of seizures during ESG play also was observed.

Adolescent↗
PubMed1999

Accuracy of screening for gastric cancer using serum pepsinogen concentrations.

BACKGROUND/AIMS: The characteristics of pepsinogen screening for gastric cancer were investigated to establish a suitable cut off point for identifying gastric cancer, using endoscopic diagnosis as the yardstick. SUBJECTS/METHODS: Serum pepsinogen concentrations were measured in 5113 subjects who were also screened for gastric cancer by endoscopy. The cut off point for pepsinogen was determined using receiver operator characteristics curves. RESULTS: The most suitable cut off point was a pepsinogen I concentration of less than 70 ng/ml and a ratio of pepsinogen I to pepsinogen II of less than 3. 0. Using this cut off point, the sensitivity and specificity of pepsinogen screening for gastric cancer were 84.6% and 73.5% respectively. All cases of gastric cancer in patients with severe atrophic gastritis were detected. However, two of four cases of gastric cancer in patients with mild atrophic gastritis were overlooked. In subjects with mild atrophic gastritis, when gastric cancer arises within the fundic gland region, the size of the lesion determines whether it is possible to detect cancer by serum pepsinogen screening. CONCLUSION: Pepsinogen screening has many advantages, including its suitability for combination with other screening methods because it is simple and inexpensive.

Aged↗
PubMed1999

Pulsed Doppler US findings of renal interlobar arteries in pregnancy-induced hypertension.

PURPOSE: To evaluate whether Doppler ultrasonographic (US) velocimetry in renal interlobar arteries is altered in women with pregnancy-induced hypertension (PIH) compared with that in healthy pregnant and nonpregnant women. MATERIALS AND METHODS: Flow waveform measurements in renal interlobar arteries were obtained in 39 nonpregnant women, 77 healthy pregnant women at 16-40 weeks gestation, and 15 women with PIH at 28-39 weeks gestation by using color and pulsed Doppler US. RESULTS: In the nonpregnant group, the mean (+/- SD) peak systolic velocity, end-diastolic blood flow velocity, resistive index, and acceleration time were 0.34 m/sec +/- 0.08, 0.14 m/sec +/- 0.03, 0.62 m/sec +/- 0.07, and 52.3 m/sec +/- 13.7, respectively. In the healthy pregnant group, the peak systolic and end-diastolic blood flow velocities at 16 weeks gestation had decreased greatly by 40 weeks gestation. However, the values of other indexes in this group did not change with gestational age. In the PIH group, the acceleration time values were greatly prolonged compared with those in the other groups. CONCLUSION: Acceleration time is one of the hemodynamic parameters of substantial upstream stenosis. These findings suggest that severe stenosis or continuous vasospasm in the proximal arteries, such as the main renal artery and segmental artery, might be implicated in the pathogenesis of PIH.

Adult↗
PubMed1999

Prediction of oligohydramnios in prolonged pregnancy.

A decrease in amniotic fluid in prolonged pregnancy is associated with increased fetal morbidity. However, few investigations have been reported on the prediction of this condition. Fetal renal arterial pulsatility index (PI), hourly fetal urine production rate (HFUPR) and amniotic fluid index (AFI) at 39 weeks were studied in 51 singleton pregnancies with (n = 14) and without oligohydramnios (AFI < 5, n = 37) in prolonged pregnancy. There was no difference in the average fetal renal arterial PI and HFUPR between the oligohydramnios group and the normal group. However, the average AFI in the oligohydramnios group was 7.5 +/- 0.9, which was lower than that in the normal group (p < 0.05). We speculated that AFI value at 39 weeks is useful for predicting the incidence of oligohydramnios in prolonged pregnancy.

Female↗
PubMed1999

Fetal middle cerebral artery Doppler waveforms in twin-twin transfusion syndrome.

The aim of this study was to compare the fetal middle cerebral artery (MCA) Doppler waveforms in growth-retarded twin fetuses with (n = 11) and without (n = 24) twin-twin transfusion syndrome (TTTS). Umbilical artery (UA) and fetal MCA Doppler velocity waveforms were recorded on admission. The mean values of the UA pulsatility index (PI) of smaller twin fetuses with and without TTTS were significantly higher than those of normal singleton pregnancies. The mean values of the MCA PI of smaller twin fetuses in the TTTS group (+0.7 +/- 1 SD) were significantly higher than those of normal singleton pregnancies on admission, and these levels did not markedly change following amniocentesis. On the other hand, the values of the MCA of the growth-retarded fetuses without TTTS (-0.9 +/- 1 SD) were significantly lower than those of normal singleton pregnancies. Our findings suggest that measurement of fetal MCA PI is a useful method to assess growth-retarded fetuses in monochorionic twin pregnancies.

Adult↗
PubMed1999

The long-lasting effect of TU-199, a novel H+, K(+)-ATPase inhibitor, on gastric acid secretion in dogs.

We have used Heidenhain-pouch dogs to investigate the effects of (+/-)-5-methoxy-2-{[(4-methoxy-3,5-dimethylpyrid-2-yl)methyl]sulph inyl}-1H-imidazo[4,5-b]pyridine (TU-199), an imidazopyridine derivative, on gastric acid secretion stimulated by histamine, carbachol and tetragastrin. We have also investigated the duration of the antisecretory effect of TU-199 using a measurement of intragastric pH for 24 h in gastric fistula dogs whose gastric acid secretion was stimulated by histamine. Single oral administration of TU-199 (0.1, 0.2 and 0.4mgkg(-1)) dose-dependently suppressed gastric acid secretion stimulated by histamine infusion. Oral treatment with TU-199 (0.2, 0.4 and 0.8 mg kg(-1)) also dose-dependently inhibited acid secretion induced by carbachol and tetragastrin. The inhibitory effect of TU-199 on stimulated gastric acid secretion was more potent than that of omeprazole, a well-known H+,K(+)-ATPase inhibitor in dogs. Repeated oral treatment with TU-199 at a dose of 0.2 mg kg(-1) once a day for seven days markedly suppressed histamine-stimulated gastric acid secretion in dogs. This inhibitory effect of TU-199 reached a maximum level after three or four doses and was more pronounced than that of omeprazole or lansoprazole. In gastric fistula dogs, the duration of intragastric pH-elevation by administration of TU-199 (0.3 mg kg(-1)) was much longer than that of omeprazole (0.6mgkg(-1)) or lansoprazole (0.9mgkg(-1)). The IC50 values (doses resulting in 50% inhibition) of TU-199, omeprazole and lansoprazole with regard to H+,K(+)-ATPase activity in dog gastric mucosal microsomes were 8.6, 8.8 and 9.9 microM, respectively. These results indicate that TU-199 inhibits gastric acid secretion via suppression of a H+,K(+)-ATPase activity. Our findings also suggest that TU-199 might have potent and long-lasting effects on gastric acid secretion.

2-Pyridinylmethylsulfinylbenzimidazoles↗