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K Aoyama

Publications and source records attributed to K Aoyama.

At least 19 recordsLinked to original sources
PubMed2006

Development of torsade de pointes caused by exacerbation of QT prolongation during clipping of cerebral artery aneurysm in a patient with subarachnoid haemorrhage.

We report the case of a 79-yr-old woman with subarachnoid haemorrhage (SAH) in whom torsade de pointes (TdP) caused by worsening the QT prolongation occurred during clipping of cerebral artery aneurysm. This patient shows a potential risk of occurrence of life-threatening tachyarrhythmia, TdP by prolonging the QT interval during surgery in patients with SAH even with no additional factors that predispose to TdP. Therefore, a proper monitoring of the QT interval is necessary as a predictor of TdP. When ventricular tachyarrhythmia occurs, recognition of TdP is important because antiarrhythmic drug therapy for TdP is different from that for ventricular tachyarrhythmias that is not TdP.

Aged↗
PubMed2006

Regulation of STAT3-mediated signaling by LMW-DSP2.

Signal transducer and activator of transcription 3 (STAT3), which mediates biological actions in many physiological processes, is activated by cytokines and growth factors, and has been reported to be constitutively activated in numerous cancer cells. In this study, we examined whether low molecular weight-dual specificity phosphatase two (LMW-DSP2) is involved in the regulation of the interleukin 6 (IL-6)/leukemia inhibitory factor (LIF)/STAT3-mediated signaling pathway. IL-6/LIF-induced LMW-DSP2 expression in murine testicular or hepatoma cell lines, while LMW-DSP2 overexpression in 293T cells suppressed IL-6-induced phosphorylation and activation of STAT3. Furthermore, LMW-DSP2 suppressed the expression of IL-6-induced endogenous genes. In contrast, small-interfering RNA-mediated reduction of LMW-DSP2 expression enhanced IL-6-induced STAT3-dependent transcription. In fact, LMW-DSP2 interacted with STAT3 in vivo and endogenous LMW-DSP2 bound to STAT3 in murine testicular GC-1 cells. These results strongly suggest that LMW-DSP2 acts as a negative regulator of the IL-6/LIF/STAT3-mediated signaling pathway.

Animals↗
PubMed2006

Aging and oxidative stress in progressive supranuclear palsy.

Progressive supranuclear palsy (PSP) is a neurodegenerative disorder, which may possibly be induced by oxidative stress. However, the age-related alteration of the endogenous antioxidant system is not well understood. To better understand this, we measured Cu/Zn-superoxide dismutase (SOD), glutathione peroxidase (GPx), and 4-hydroxynonenal (HNE)-conjugated GPx in cerebrospinal fluid of PSP patients by enzyme linked immunosorbent assay. A significant increase in the Cu/Zn-SOD level was detected in PSP group compared with controls. The levels of Cu/Zn-SOD and GPx in PSP group showed positive correlations with age. Two-thirds of total GPx was present as the HNE-conjugated form with positive correlation in PSP group. In conclusion, the endogenous antioxidant system of PSP patients appears to be activated with aging, however, it might be unable to function effectively because of conjugation with HNE.

Age Factors↗
PubMed2004

Two cases of left-sided gastroschisis: review of the literature.

In gastroschisis, the opening is almost always to the right of the umbilicus, although eight cases of left-sided gastroschisis have been reported in the literature. We encountered two additional cases of left-sided gastroschisis. One was treated successfully, but the another child died. We report the present two these two cases and a review of the literature.

Female↗
PubMed2003

Release of recombinant human bone morphogenetic protein 2 from a newly developed carrier.

After implantation of a polymer-coated gelatin sponge (PGS) containing either 0.4 or 1.0 mg of 125I-rhBMP-2 for each 1 cm(3) of PGS into the right ulnar of rabbits, changes in the level of radioactivity at the implant site and in the blood were measured for 21 days after implantation, and the cumulative excretion ratio of radioactivity in the urine and feces was calculated. For both doses, radioactivity at the implant site was eliminated biphasically. The concentration of trichloroacetic acid (TCA)-precipitable radioactivity in the blood reached a maximum 6 h after implantation, at which time it was equivalent to 1.41% of the administered dose (0.4 mg/cm(3)). The remaining radioactivity was eliminated rapidly thereafter, falling below the detection limit within 48 h. The t(1/2alpha) was about 0.1 days, the t(1/2beta) was about 3 days, and the mean resident time (MRT) value was about 4 days. By 17 days after implantation, 88.1% of the administered radioactivity had been excreted in the urine, and 1.7% had been excreted in the feces. TCA precipitation test results indicated that most of the radioactivity excreted in urine was a low-molecular weight decomposition product. At 21 days after implantation, the radioactivity of the PGS implant site had declined to 0.5% of the administered amount. Autoradiographs of the implant site taken 28 days after implantation revealed that, at both doses, the residual radioactivity was confined to the area of the implanted PGS. These results indicate that PGS retains an appropriate amount of recombinant human bone morphogenetic protein 2 (rhBMP-2) at the orthotopically implanted site for at least 21 days enough to induce bone regeneration. Thus, PGS shows great clinical potential as a carrier for rhBMP-2.

Animals↗
PubMed2002

Positive pressure ventilation during fibreoptic intubation: comparison of the laryngeal mask airway, intubating laryngeal mask and endoscopy mask techniques.

BACKGROUND: The efficacy of delivery of mechanical ventilation through different airway devices during fibreoptic intubation is not known. METHODS: We compared the laryngeal mask airway (LMA), intubating laryngeal mask (ILM) and endoscopy mask for positive pressure ventilation (PPV) during fibreoptic intubation. In 80 adult paralysed patients, fibreoptic intubation was performed during PPV using a combination of a size 3 or 4 LMA with a 6.0 mm nasal RAE tracheal tube (LMA3/4 group; n=22), a size 5 LMA with a 7.0 mm nasal RAE tube (LMA5 group; n=18), an ILM with an 8.0 mm special reinforced tracheal tube (ILM group; n=20) or an endoscopy mask (Patil mask) with a 7.5 mm standard tracheal tube (Patil group; n=20). The inspiratory and expiratory tidal volumes (VI and VE) with a ventilation pressure of 20 cm H2O were measured using a pneumotachograph. RESULTS: Mean VE values during fibreoptic intubation in the LMA5 [5.3 (SD 1.5) ml kg(-1)] and ILM [7.1 (2.3) ml kg(-1)] groups were greater than in the LMA3/4 group [2.6 (1.0) ml kg(-1), P<0.0001]. The mean VE was greater in the Patil group [20.6 (4.9) ml kg(-1)] than in the other three groups (P<0.0001). Gastric insufflation during intubation was more frequent in the Patil group (30%) than in the other three groups (4.5-5.6%) (P<0.05). CONCLUSION: PPV is possible with the LMA, ILM or endoscopy mask during fibreoptic intubation. With an airway pressure of 20 cm H2O, ventilation during intubation using a size 3 or 4 LMA was almost insufficient, while ventilation using a size 5 LMA or an ILM was almost acceptable. Ventilation during intubation with the endoscopy mask was greater than that with the LMA or ILM, but gastric insufflation was more frequent.

Adult↗
PubMed2001

Carrier-mediated processes in blood--brain barrier penetration and neural uptake of paraquat.

Due to the structural similarity to N-methyl-4-phenyl pyridinium (MPP(+)), paraquat might induce dopaminergic toxicity in the brain. However, its blood--brain barrier (BBB) penetration has not been well documented. We studied the manner of BBB penetration and neural cell uptake of paraquat using a brain microdialysis technique with HPLC/UV detection in rats. After subcutaneous administration, paraquat appeared dose-dependently in the dialysate. In contrast, MPP(+) could not penetrate the BBB in either control or paraquat pre-treated rats. These data indicated that the penetration of paraquat into the brain would be mediated by a specific carrier process, not resulting from the destruction of BBB function by paraquat itself or a paraquat radical. To examine whether paraquat was carried across the BBB by a certain amino acid transporter, L-valine or L-lysine was pre-administered as a co-substrate. The pre-treatment of L-valine, which is a high affinity substrate for the neutral amino acid transporter, markedly reduced the BBB penetration of paraquat. When paraquat was administered to the striatum through a microdialysis probe, a significant amount of paraquat was detected in the striatal cells after a sequential 180-min washout with Ringer's solution. This uptake was significantly inhibited by a low Na(+) condition, but not by treatment with putrescine, a potent uptake inhibitor of paraquat into lung tissue. These findings indicated that paraquat is possibly taken up into the brain by the neutral amino acid transport system, then transported into striatal, possibly neuronal, cells in a Na(+)-dependent manner.

1-Methyl-4-phenylpyridinium↗
PubMed2001

Molecular cloning and characterization of a novel dual specificity phosphatase, LMW-DSP2, that lacks the cdc25 homology domain.

A novel dual specificity phosphatase (DSP) designated LMW-DSP2 was cloned with a combination of reverse transcription-polymerase chain reaction and cDNA library screening strategies. The LMW-DSP2 open reading frame of 194 amino acids contained a single DSP catalytic domain but lacked the cdc25 homology domain, which is conserved in most known DSPs. Northern blot and reverse transcription-polymerase chain reaction analyses revealed that LMW-DSP2 was specifically expressed in testis. Recombinant LMW-DSP2 protein exhibited phosphatase activity toward an artificial low molecular weight substrate para-nitrophenyl phosphate, and the activity was inhibited completely by sodium orthovanadate but not sodium fluoride, pyrophosphate, and okadaic acid. The substitution of critical amino acid residues, aspartic acid and cysteine, resulted in a dramatic reduction of phosphatase activity. Transient transfection of LMW-DSP2 in COS7 cells resulted in the expression of a 21-kDa protein, and the phosphatase was shown to be distributed in both the cytosol and the nucleus. LMW-DSP2 dephosphorylated and deactivated p38, to a higher extent, and stress-activated protein kinase (SAPK)/c-Jun N-terminal kinase (JNK), but not extracellular signal-regulated kinase 1/2 mitogen-activated protein kinases, in transfected COS7 cells and in vitro. Interestingly, mutation in a conserved docking motif of p38 and SAPK/JNK as well as in a cluster of aspartic acids of LMW-DSP2 did not affect the deactivation of the mitogen-activated protein kinases by LMW-DSP2. Furthermore, the binding between LMW-DSP2 and p38 and SAPK/JNK was also not disrupted by such mutations. Among the DSPs lacking the cdc25 homology domain, LMW-DSP2 is the first one that dephosphorylates and deactivates p38 and SAPK/JNK.

Amino Acid Sequence↗
PubMed2001

Nicotinamide-N-methyltransferase is higher in the lumbar cerebrospinal fluid of patients with Parkinson's disease.

Parkinson's disease (PD) may be initiated or precipitated by endogenous toxins with a structure similar to 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine in genetically-predisposed individuals. Nicotinamide N-methyltransferase (NNMT) catalyzes N-methylation of nicotinamide and other pyridines to form pyridinium ions. The protein amount of NNMT was measured in the lumbar cerebrospinal fluid of PD patients by immunoblot analysis using anti-human NNMT antibody. In younger (65 years old or younger) PD patients, the relative level of NNMT protein was significantly higher than that in younger controls. The NNMT protein was significantly affected by aging: the amount decreased along with aging in PD patients. These findings suggested that excess NNMT in the central nervous system might be implicated in the PD pathogenesis.

Aging↗
PubMed2001

Gastric pneumatosis associated with duodenal stenosis and malrotation.

Pneumatosis intestinalis, which is linear or cystic gas within the bowel wall, is usually found in premature babies in association with necrotizing enterocolitis. Gastric pneumatosis defined as intramural gas of the stomach is a rare sign during infancy. We report an infant with Down's syndrome and a duodenal web with obvious gastric pneumatosis.

Down Syndrome↗
PubMed2001

A growing family of dual specificity phosphatases with low molecular masses.

Five putative dual specificity protein phosphatases (DSPs), designated LMW-DSP1, -DSP4, -DSP6, -DSP10, and -DSP11, were cloned with a combination of RT-PCR and cDNA library screening strategies. Sequencing analysis revealed that all lacked the cdc25 homology domain that is conserved in most known DSPs/MAP kinase phosphatases (MKPs). LMW-DSP1 exhibited the highest similarity to plant DSPs. LMW-DSP4 exhibited the highest similarity to human YVH1 and rat GKAP, but its C-terminal region was much shorter than that of the human and rat clones. LMW-DSP6 was found to be identical to recently cloned TMDP, and LMW-DSP11 seemed to be a mouse ortholog of human VHR. LMW-DSP10 was found to have a DSP catalytic-like domain, but the critical cysteine residue for catalytic activity was missing. Recombinant LMW-DSP1, -DSP6, and -DSP11 exhibited obvious and strong activity against an artificial low molecular substrate, para-nitrophenyl phosphate (pNPP). Recombinant LMW-DSP4 exhibited slight but significant activity, whereas no activity was detected for LMW-DSP10. The phosphatase activity of the recombinant LMW-DSPs was inhibited by orthovanadate but not sodium fluoride. However, none of the DSPs could dephosphorylate MAP kinases such as ERK1, p38, and SAPK/JNK in transiently transfected COS7 cells under the conditions used. Northern blot analysis revealed that LMW-DSP1, -DSP6, -DSP10, and -DSP11 were specifically expressed in testis, while LMW-DSP4 was broadly expressed. The testis-specific expression and apparent absence of dephosphorylation action on MAP kinases suggest that LMW-DSP1, -DSP6, -DSP10, and -DSP11 play specific roles in testis. Taken together, it is conceivable that a distinct class of low molecular mass DSPs is present and plays a role in dephosphorylating unknown molecules other than MAP kinases.

Amino Acid Sequence↗
PubMed2001

Post-transplant malignant lymphoma with monoclonal immunoglobulin gene rearrangement and polyclonal Epstein-Barr virus episomes.

This report describes the case of an 8 year old boy who developed ileocecal B cell lymphoma after liver transplantation. The patient underwent orthotopic liver transplantation for biliary atresia and had been given immunosuppressive drugs--cyclosporin A and tacrolimus hydrate. Six years after the liver transplantation, the patient had a sudden onset of fever and abdominal pain. Necropsy revealed an ileocecal mass that was a B cell lymphoma. Epstein-Barr virus (EBV) encoded RNA 1 was demonstrated in lymphoma cells and hyperplastic follicular germinal centre cells in various tissues. Although monoclonal immunoglobulin gene rearrangement was detected in the liver, EBV episomes were of polyclonal origin and lytic forms of EBV were also demonstrated by Southern blotting. Immunohistochemically, lymphoma cells were positive for p53 but negative for latent membrane protein 1 and EBV nuclear antigen 2. These findings suggested that this B cell lymphoma might have occurred sporadically, regardless of EBV infection.

Biliary Atresia↗
PubMed2001

Genetic analysis of the His-to-Asp phosphorelay implicated in mitotic cell cycle control: involvement of histidine-kinase genes of Schizosaccharomyces pombe.

Common histidine-to-aspartate (His-to-Asp) phosphorelay signaling systems involve three types of signaling components: a sensor His-kinase, a response regulator, and a histidine-containing phosphotransfer (HPt) protein. In the fission yeast Schizosaccharomyces pombe, two response regulators, Mcs4 and Prr1, have been identified, and it was shown that they are involved in signal transduction in stress responses. Furthermore, Mcs4 and Prr1 appear to be involved in mitotic cell-cycle control and meiosis, respectively. Recently we have identified Spy1 (also known as Mpr1), which encodes an HPt phosphotransmitter, and reported that Spy1, together with Mcs4, plays a role in cell cycle regulation. In this study, we identified and characterized three genes encoding histidine kinase, named Phk1, Phk2, and Phk3 (S. pombe histidine kinase) (also referred as Mak2, Mak3, and Mak1, respectively). Deletion of individual kinase genes has no apparent phenotypes but multiple deletion of these kinases showed the same phenotype of Spyl (Mpr1)-deficient cells, indicating precocious entry into M phase. These results indicated that three histidine kinases that work upstream of the HPt-transmitter, Spy1 (Mpr1), have a redundant function in cell cycle control.

Amino Acid Sequence↗
PubMed2001

Habituation contributes to within-session changes in free wheel running.

Three experiments tested the hypothesis that habituation contributes to the regulation of wheel running. Rats ran in a wheel for 30-min sessions. Experiment 1 demonstrated spontaneous recovery. Rats ran more and the within-session decreases in running were smaller after 2 days of wheel deprivation than after 1 day. Experiment 2 demonstrated dishabituation. Running rate increased immediately after the termination of a brief extra event (application of the brake or flashing of the houselight). Experiment 3 demonstrated stimulus specificity. Rats completed the second half of the session in either the same wheel as the first half, or a different wheel. Second-half running was faster in the latter case. Within-session patterns of running were well described by equations that describe data from the habituation, motivation, and operant literatures. These results suggest that habituation contributes to the regulation of running. In fact, habituation provides a better explanation for the termination of wheel running than fatigue, the variable to which this termination is usually attributed. Overall, the present findings are consistent with the proposition that habituation and sensitization contribute to the regulation of several forms of motivated behavior.

Animals↗