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H Yamamura

Publications and source records attributed to H Yamamura.

At least 109 records · Page 6Linked to original sources
PubMed1997

Identification of a novel Drosophila protein kinase highly homologous to protein kinase N (PKN).

We identified a novel Drosophila gene, Dpkn (Drosophila protein kinase related to PKN), encoding a putative protein serine/threonine kinase. Although the cDNA obtained was incomplete at its 5'-terminal region, the deduced amino acid sequence of its kinase domain exhibits a high degree of similarity to protein kinase N (PKN), which has a kinase domain related to protein kinase C (PKC) and leucine zipper-like sequences in the amino terminal region. Expression of Dpkn was observed throughout Drosophila development, although its expression level decreased at later stages of embryogenesis. The expression of Dpkn is first detected in the newly formed mesodermal cell layer and is then restricted to the developing somatic musculature, indicating a possible role of Dpkn in the development of somatic muscles in Drosophila.

Amino Acid Sequence↗
PubMed1997

syk kinase activation by a src kinase-initiated activation loop phosphorylation chain reaction.

Activation of the syk tyrosine kinase occurs almost immediately following engagement of many types of antigen receptors, including Fc receptors, but the mechanism through which syk is activated is currently unclear. Here we demonstrate that Fc receptor-induced syk activation occurs as the result of phosphorylation of the syk activation loop by both src family kinases and other molecules of activated syk, suggesting that syk activation occurs as the result of a src kinase-initiated activation loop phosphorylation chain reaction. This type of activation mechanism predicts that syk activation would exhibit exponential kinetics, providing a potential explanation for its rapid and robust activation by even weak antigen receptor stimuli. We propose that a similar mechanism may be responsible for generating rapid activation of other cytoplasmic tyrosine kinases, such as those of the Bruton tyrosine kinase/tec family, as well.

3T3 Cells↗
PubMed1997

Assay for the (R)- and (S)-enantiomers of salsolinols in biological samples and foods with ion-pair high-performance liquid chromatography using beta-cyclodextrin as a chiral mobile phase additive.

A chromatographic procedure was devised for the quantitative determination of the enantiomers of salsolinol and N-methylsalsolinol, which are biologically important alkaloids. The enantiomers of salsolinol and N-methylsalsolinol were completely separated using beta-cyclodextrin in a reversed-phase ion-pair system. The HPLC method was sensitive enough to detect the isoquinolines at a concentration less than 0.1 pmol per injection. The presence of (R)- and (S)-salsolinol was confirmed in fermented foods and beverages, while N-methylsalsolinol was not detected. On the other hand, the (R)-enantiomers of both salsolinol and N-methylsalsolinol were found to predominate in the human brain.

Beverages↗
PubMed1997

Syk-dependent and -independent signaling cascades in B cells elicited by osmotic and oxidative stress.

It was found that Syk protein-tyrosine kinase is rapidly activated in B cells after H2O2 treatment (oxidative stress) or increased extracellular NaCl concentration (osmotic stress) as well as in response to B cell receptor activation. In this study we examined the involvement of Syk in responses elicited by these types of extracellular stress, particularly Ca2+ responses and c-Jun amino-terminal kinase (JNK) activation, using a chicken B cell line, DT40, as well as the DT40-derived mutant DT40/Syk(-), which does not express Syk. Osmotic stress evokes increases in [Ca2+]i by stimulating an extracellular Ca2+ influx in both DT40 and DT40/Syk(-) cells. In comparison, oxidative stress elicits an increase in [Ca2+]i by stimulating both an extracellular Ca2+ influx and Ca2+ release from internal stores in DT40 cells, but this Ca2+ response is partially abolished in DT40/Syk(-) cells, indicating that the oxidative stress-induced Ca2+ response is at least partly dependent on Syk. Interestingly, the depletion of Ca2+ results in a significantly decreased level of Syk activation in DT40 cells stimulated by oxidative but not osmotic stress. Furthermore, JNK is activated to different extents by these two types of stress. The extent of JNK activation in DT40/Syk(-) cells in response to osmotic stress is comparable to that observed in DT40 cells. Intriguingly, oxidative stress-induced JNK activation is significantly compromised in DT40/Syk(-) cells. Collectively, these results indicate that both the Ca2+ response and JNK activity induced by oxidative stress are partly dependent on Syk, whereas those induced by osmotic stress are independent of Syk.

Animals↗
PubMed1997

Effects of prenatal treatment with tritiated water on the developing brain in mouse.

Pregnant mice were injected intraperitoneally with various doses of tritiated water on embryonic day 13. The litters received total cumulative absorbed beta-irradiation to a dose of 0, 0.1, 0.2, 0.4 or 0.8 Gy. We found that 0.4 Gy beta-irradiation caused a significant reduction in brain weight but not in body weight among 8-week-old mice. The highest dose (0.8 Gy) inhibited both body and brain development. A quantitative study showed that a significant reduction in cerebral pyramidal cells was present in the groups exposed to > or = 0.2 Gy. In tritiated, water-treated groups, the pyramidal cells reduced in a dose-dependent manner, with reductions ranging from 3 to 12%. The thickness of cerebral cortex was significantly reduced in the groups exposed to > or = 0.4 Gy. Numerical density of pyramidal cells was the most sensitive indicator of developmental disturbance of cerebral cortex manifested postnatally. No significant difference in the numerical density of Purkinje cells was found between the irradiated and control groups. These results demonstrated that the time at which the insult occurred was an important factor determining the resulting abnormalities.

Animals↗
PubMed1997

Tyrosine phosphorylation and Syk activation are involved in thrombin-induced aggregation of epinephrine-potentiated platelets.

Thrombin and epinephrine in combination exert synergistic effects on platelet activation. On the other hand, tyrosine phosphorylation and activation of tyrosine kinases including Syk have been shown to play a critical role in the induction of platelet responses to thrombin stimulation. This study investigated the role of tyrosine phosphorylation and Syk activation in the synergistic mechanisms between thrombin and epinephrine. Although epinephrine alone (4 microM) slightly induced protein-tyrosine phosphorylation and Syk activation, the presence of epinephrine caused a shift to the left in the dose-dependence of thrombin (0.01-0.5 U/ml)-induced tyrosine phosphorylation and Syk activation, as well as platelet aggregation. Phenoxybenzamine, an alpha-adrenoceptor antagonist, canceled this potentiation by epinephrine. Since platelets dominantly express alpha 2-adrenoceptor, this result indicates that epinephrine acts through the occupancy of alpha 2-adrenoceptor. Furthermore, pretreatment with a tyrosine kinase inhibitor, genistein, or a cAMP-elevating agent, prostacyclin (PGI2), significantly reduced these synergistic effects of epinephrine. Taken together, our results suggested that the potentiation by epinephrine may be mediated via enhancement of tyrosine phosphorylation and Syk activation, in part through a decrease of intracellular cAMP levels.

Adrenergic alpha-Agonists↗
PubMed1997

Structure and expression of the human SM22alpha gene, assignment of the gene to chromosome 11, and repression of the promoter activity by cytosine DNA methylation.

To investigate the molecular mechanisms that control expression of smooth muscle cell (SMC) differentiation genes, we have isolated the human SM22a gene, which is composed of five exons and four introns, spanning an approximately 6-kilobase (kb) genomic DNA at chromosome region 11q23.2. Expression of the SM22a messenger RNA was detected in serum-stimulated cell cultures including SMC, undifferentiated skeletal muscle-lineage cells, and fibroblasts, and it was down-regulated in SMC of balloon-injured atheromatous human vessels. A major transcription start site of the SM22alpha gene is located at 75 base-pairs (bp) upstream of the ATG start codon. Analysis of the 2.6 kb 5'-upstream sequence demonstrated that two CArG/SRF-boxes and two GC-box/Sp1-binding sites were present at bp -147 and -274, and at bp -233 and -1635, respectively. The nucleotide sequences of the two CArG/SRF-boxes and the proximal GC-box/Sp1 binding site are 100% conserved with those of the murine SM22alpha genes [Solway, J., Seltzer, J., Samaha, F.F., Kim, S., Alger, L.E., Niu, Q., Morriesey, E.E., Ip, H.S., and Parmacek, M.S. (1995) J. Biol. Chem. 270, 13460-13469; Kemp, P.R., Osbourn, J.K., Grainger, D.J., and Metcalf, C. (1995) Biochem. J. 310, 1037-1043]. Cell transfection assays using a luciferase reporter gene construct containing the 455-bp 5'-flanking region (positions -26 to -480) showed that methylation of the CpG dinucleotides within this segment reduces its transcriptional activity. The results imply a novel mechanism for transcriptional control of the SMC differentiation-specific gene promoter.

Amino Acid Sequence↗
PubMed1997

Analysis of 372 patients with Crush syndrome caused by the Hanshin-Awaji earthquake.

OBJECTIVE: To clarify clinical features and determine the severity of injuries in patients with crush syndrome in Hanshin-Awaji earthquake. METHODS: We retrospectively reviewed medical records of 6,107 patients hospitalized in 95 hospitals, and identified 372 patients with crush syndrome. RESULTS: The major sites of crush injury were in the lower extremities (74%), followed by the upper extremities (10%), and the trunk (9%). Pelvic fractures, limb fractures, and abdominal injuries were the most frequently associated injury. Patients with trunk compression and/or with abdominal injury had a higher mortality rate. A total of 50 patients (13.4%) died. The causes of death within 5 days after the earthquake were hypovolemia and hyperkalemia. Peak serum creatine kinase concentration increased with the number of crushed extremities. Mortality and the risk of acute renal failure were higher in patients with creatine kinase concentration more than 75,000 micro/L. CONCLUSIONS: Peak serum concentration of creatine kinase as well as the number of injured extremities serve to estimate the severity of crush syndrome.

Abdominal Injuries↗
PubMed1997

Analysis of 2,702 traumatized patients in the 1995 Hanshin-Awaji earthquake.

BACKGROUND: This study was undertaken to define the factors that affected the final outcome of trauma patients in the Hanshin-Awaji earthquake. METHODS: Medical records of patients admitted to 95 hospitals within or surrounding the affected area during the first 15 days after the quake were reviewed. RESULTS: There were 2,702 traumatized patients. One-third of the patients were transported to hospitals in the surrounding area and had a mortality rate of 3%. The remainder, who were treated in the affected hospitals, showed a significantly higher mortality rate (8%; p < 0.05). Intensive care was provided for 513 patients, most of whom suffered from crush syndrome or from injuries to vital organs; these patients had a high mortality rate. Patients with other types of injuries had a lower mortality rate. CONCLUSION: Crush syndrome and injuries to vital organs were potentially life-threatening. We believe that early transportation of such patients to undamaged hospitals with the ability to provide intensive care would have improved the survival rate.

Abbreviated Injury Scale↗
PubMed1997

A new model of experimental allergic rhinitis using Japanese cedar pollen in guinea pigs.

In the majority of the models of experimental allergic rhinitis, antigen challenge has been performed by single topical instillation or perfusion with the solution. The present study was performed to establish a good model using Japanese cedar pollen, which is able to repeatedly induce allergy restricted to the upper airway. Guinea pigs sensitized with the pollen extracts were subjected to quantitative and repeated inhaling of the pollen with a devised apparatus. Following the respective challenges, the nasal cavity was washed with a new technique: Washing with physiologic saline was performed from one nostril to the other one, the latter of which was kept under slightly reduced pressure. When the animal was subjected to cedar pollen inhalation, almost all the pollens inhaled were located in the upper airway. At the 5th inhalation, nasal cavity lavage revealed that both albumin leakage and histamine release into the nasal cavity were increased at maximum levels in 1 hr (respectively 2 mg and 3 ng/animal); and at the same time, a considerable number of leukocytes, especially eosinophils, were found migrating into the nasal cavity for at least 10 hr. The present methods can permit various analyses of allergic rhinitis and the assessment of drugs without sacrificing the animal over the long term.

Albumins↗
PubMed1997

Repeated antigen inhalation-induced reproducible early and late asthma in guinea pigs.

To develop a model of chronic experimental asthma in guinea pigs, the animal was forced to inhale the mist of a low dose of ovalbumin (OA) adsorbed on fine Al(OH)3 for sensitization once every 4 weeks. The animal was challenged by inhalation with the mist of OA on day 14 after the respective sensitizations. Either the first or the second antigen challenge markedly induced an early asthmatic response (EAR), whereas there was hardly any late asthmatic response (LAR). At the 3rd challenge, LAR also emerged with some severity. These dual responses were consistently observed until the 10th challenge. On the other hand, repeated inhalation/challenge, once every 2 weeks, with OA alone at the same dose tended to lead to the desensitization of the EAR. In addition, LAR was hardly observed throughout the experiments. In both groups, gamma 1 and IgE levels in the serum were elevated by the repetitive antigen inhalations, yet no obvious relationship between these antibody levels and the intensity of either EAR or LAR was recognized. The present results indicate that the asthmatic model with reproducible EAR and LAR developed in this study appears to be very beneficial for the investigation of bronchial asthma and for the assessment of anti-asthma drugs.

Administration, Inhalation↗
PubMed1997

Idiopathic renal hematuria in a dog; the usefulness of a method of partial occlusion of the renal artery.

Exploratory laparotomy was performed on a dog suspected of having idiopathic renal hematuria. Two catheters were inserted into the bilateral ureters, and hematuria from the left kidney was confirmed. The blood flow was occluded in the ventral and dorsal rami of the left renal artery in order to localize the site of hemorrhage. As hematuria disappeared when the dorsal ramus was occluded, the site of renal hematuria was localized to the area dominated by the dorsal ramus of the renal artery. As a result of ligating the dorsal ramus of the left renal artery in this dog, renal hematuria subsided, and the dog has shown a favorable course, to date, one year after surgery.

Animals↗
PubMed1997

[Encephalitis located at bilateral corpus callosum on MRI--a case report].

A case of viral encephalitis is described. A 38 year-old female was admitted because of high fever accompanied by cough and headaches. Two days after admission the patient began to exhibit abnormal behavior. Cerebrospinal fluid examination revealed pleocytosis. T2-weighted MRI revealed a high-intensity area located in the corpus callosum bilaterally that gradually increased in intensity within several days the patient's behavior returned to normal. The high-intensity area on MRI persisted for several months but diminished in intensity. Rubella may have been the etiology of the encephalitis.

Adult↗
PubMed1997

[A case of thymic cyst and thymoma with myasthenia gravis].

A case of 53-year-old male with thymic cyst was reported. We established diagnosis for myasthenia gravis. The chest CT and MRI demonstrated a cystic and mass lesion on the anterosuperior mediastinum. This finding suggested a thymic cyst and tumor with myasthenia gravis. The extended thymectomy was performed. Histological examination demonstrated the clear separation of the mixed type thymoma and the thymic cyst. The few reported cases of thymic cyst and thymoma with myasthenia gravis were reviewed.

Humans↗
PubMed1997

Eosinophil chemotaxis induced by several biologically active substances and the effects of apafant on it in vitro.

Chemotaxis of guinea pig eosinophils induced by various stimuli in use of a modified Boyden chamber technique in vitro and the effect of a platelet-activating factor (PAF) antagonist, apafant (CAS 105219-56-5, WEB 2086 BS), on it were examined. The eosinophils were obtained by bronchoalveolar lavage from the animals treated by i.v. injection with Sephadex G-200 and purified by Percoll density gradient centrifugation. PAF significantly and potently induced the chemotaxis at a broad range of 10(-17) to 10(-7) mol/l, where no concentration-dependency was observed. Leukotriene B4 also induced the chemotaxis in a concentration-dependent manner at 10(-14) to 10(-12) mol/l and the enhanced migration was not declined until 10(-7) mol/l. Interleukin-5 (IL-5), IL-8 and regulated on activation normal T expressed and secreted (RANTES) only modestly enhanced the chemotaxis in some concentrations at 10(-13) to 10(-7) mol/l with or without significance and with no concentration-dependency while formyl-methionyl-leucyl-phenylalanine (FMLP), a known chemoattractant, increased the migration at 10(-7) to 10(-5) mol/l. Apafant at 10(-8) to 10(-6) mol/l strongly and concentration-dependently inhibited 10(-8) mol/l PAF-induced chemotaxis. However, the drug showed nominal or no influences on their chemotaxis stimulated by the other agonists, at the concentrations of which the enhanced migration was observed. From these results, it is concluded that IL-5, IL-8 and RANTES, different from PAF and LTB4, are not potent stimuli for the eosinophil chemotaxis and that apafant is a selective antagonist of PAF, which is expected to be therapeutically effective for PAF-associated diseases including bronchial asthma.

Animals↗
PubMed1997

[Percutaneous transcatheter thermotherapy (PTCT): use of hotwire for local tumor control].

We developed a Hotwire for use in percutaneous transcatheter thermotherapy (PTCT) for local tumor control. The Hotwire has a temperature sensor and a heater, and is inserted into the hepatic artery through a Y-connector and an angiocatheter. It can then warm fluid from the Y-connector to 45 degrees C under electorical control PTCT was performed on liver tumors using 4 mg of MMC and 10 mg Epirubicin. The antitumor effects and indications for PTCT were investigated in patients with unresectable liver tumors, including 3 patients who had hepatocellular carcinoma (HCC) with intraportal invasion and collateral vessels, one patient with liver metastasis of rectal cancer, and two gastric cancer patients. In all patients, tumor marker levels decreased (PIVKA-II; 8.5-->0.9, 2.9-->0.9, AFP; 1154-->753, CEA; 300-->226, TPA; 6319-->4227, 3312-->943), and CRP levels were markedly elevated with tumor fever. The only adverse reaction to PTCT was nausea and vomiting in one female patient. We repeated PTCT 6 times for giant HCC, and performance status was improved (2-->0). In conclusion, PTCT using the Hotwire is useful for treating hypervascular tumors limited to the liver, especially HCC with intraportal invasion and collateral vessels.

Aged↗