Biomedical subjects

K Nagai

Publications and source records attributed to K Nagai.

At least 127 records · Page 7Linked to original sources

PubMed2000

E-73, an acetoxyl analogue of cycloheximide, blocks the tumor necrosis factor-induced NF-kappaB signaling pathway.

Proinflammatory cytokines such as tumor necrosis factor (TNF) and interleukin (IL)-1 activate the NF-kappaB signaling pathway which induces the expression of a variety of genes such as the encoding intercellular adhesion molecule (ICAM)-1. We have found that E-73, an acetoxyl analogue of cycloheximide, specifically blocks TNF-induced ICAM-1 expression even at concentrations unable to affect protein synthesis. By contrast, cycloheximide inhibited both TNF- and IL-1-induced ICAM-1 expression primarily due to the blockage of protein synthesis. The nuclear translocation of NF-kappaB as well as the IkappaB degradation induced by TNF, but not by IL-1, was significantly prevented by E-73. These observations suggest that E-73 blocks the TNF-induced NF-kappaB signaling pathway upstream of IkappaB degradation.

Blotting, Western↗

PubMed2000

Light and glutamate-induced degradation of the circadian oscillating protein BMAL1 during the mammalian clock resetting.

Recently discovered mammalian clock genes are believed to compose the core oscillator, which generates the circadian rhythm. BMAL1/CLOCK heterodimer is the essential positive element that drives clock-related transcription and self-sustaining oscillation by a negative feedback mechanism. We examined BMAL1 protein expression in the rat suprachiasmatic nuclei (SCN) by immunoblot analysis. Anti-BMAL1 antiserum raised against rBMAL1 recognized 70 kDa mBMAL1b and detected a similar immunoreactivity (IR) as a major band in rat brains. Robust circadian BMAL1-IR oscillations with nocturnal peaks were detected in the SCN during a light/dark cycle and under constant darkness. A short duration light exposure at night acutely reduced BMAL1-IR in the SCN during photoentrainment. This might be attributable to the degradation of BMAL1 protein. Application of glutamate and NMDA to the SCN slices at projected night, a procedure mimicking photic phase delay shift, also acutely reduced BMAL1-IR in a similar manner. A rapid decrease of BMAL1 protein suggests that BMAL1 protein might be implicated in the light-transducing pathway within the SCN.

ARNTL Transcription Factors↗

PubMed2000

Depression after successful treatment for nonsmall cell lung carcinoma.

BACKGROUND: There have been few studies of depression in nonsmall cell lung carcinoma (NSCLC) patients after successful treatment. The purpose of the study was to clarify the prevalence and the correlated factors of depression after surgery. METHODS: A structured interview was conducted for patient characteristics and social support with NSCLC patients at baseline. One-month prevalence of depression at 1 and 3 months after surgery was obtained by follow-up interviews at 1 and 3 months after surgery, respectively, whereas that of depression at 2 months after surgery was by the latter interview retrospectively. Three-month prevalence of depression was determined as presence of depression during any month in of a period of 3 months after surgery. A logistic analysis was used to examine the correlated factors of depression during the 3 months after surgery. RESULTS: Of 223 consecutive cancer patients who participated in the study between June 1996 and April 1999, 33 (14.8%) met the criteria for major or minor depression during the 3 months after surgery. One-month prevalence of depression at 1, 2, and 3 months after surgery were 9.0%, 9.4%, and 5.8%, respectively. The results of logistic regression analysis revealed that only satisfaction with confidants before surgery, of patient characteristics and social support factors, was significantly associated with depression during the 3 months after surgery. CONCLUSIONS: These results suggest that depression is not rare after successful treatment for NSCLC and that social support may play an important role for NSCLC patients with depression after successful treatment.

Adult↗

PubMed2000

Santonin-related compound 2 inhibits the expression of ICAM-1 in response to IL-1 stimulation by blocking the signaling pathway upstream of I kappa B degradation.

Santonin-related compounds (SRCs) were synthesized from the starting material L-alpha-santonin and tested for the biological activity on the expression of intercellular adhesion molecule-1 (ICAM-1) in response to IL-1 stimulation on human adenocarcinoma cells. One of the bromoketone derivatives termed SRC2 [11S-2 alpha-bromo-3-oxoeudesmanno-13,6 alpha-lactone] strongly inhibited the ICAM-1 expression at an IC(50) value of 5.9 microM, whereas L-alpha-santonin itself was totally inactive up to 100 microM. The blockage of ICAM-1 expression by SRC2 was not due to the direct inhibition of de novo RNA and protein synthesis. The nuclear translocation of NF-kappaB subunit p65 was markedly prevented by SRC2. Moreover, I kappa B alpha degradation upon IL-1 stimulation was strongly inhibited by SRC2. These observations suggest that SRC2 blocks the IL-1 signaling pathway upstream of I kappa B degradation.

Biological Transport↗

PubMed2000

Cloning and characterization of rat casein kinase 1epsilon.

Genes differentially expressed in the subjective day and night in the rat suprachiasmatic nucleus (SCN) were surveyed by differential display. A gene homologous to human casein kinase 1epsilon (CK1epsilon) was isolated, which initially appeared to be expressed in the suprachiasmatic nucleus (SCN) in a circadian manner. We here describe the cDNA cloning of the rat CK1epsilon and characterization of the protein products. The rCK1epsilon is predominantly expressed in the brain including the SCN, binds and phosphorylates mPer1, mPer2, and mPer3 in vitro, and translocates mPer1 and mPer3, but not mPer2, to the cell nucleus depending on its kinase activity when coexpressed with these Per proteins in COS-7 cells.

Alternative Splicing↗

PubMed2000

Changes in circadian period and morphology of the hypothalamic suprachiasmatic nucleus in fyn kinase-deficient mice.

Protein tyrosine phosphorylation is involved in intracellular signal transduction and plays important roles in various physiological events. To understand the role of Fyn, a non-receptor type tyrosine kinase of Src family kinases, in the mechanism of circadian rhythms, we analyzed the circadian locomotor behavior and morphology of the hypothalamic suprachiasmatic nucleus (SCN), a master circadian oscillator in Fyn mutant mice, because Fyn-like immunoreactive substance was observed in the SCN. Under constant dark (DD) condition the Fyn (-/-) mutant mice showed a free-running circadian rhythm, and the period of the circadian rhythm of the locomotor activity was significantly longer than that of the control mice. Fyn (-/-) mutant mice had abnormal distribution of neurons containing vasoactive intestinal polypeptide (VIP)-like immunoreactive substance in the SCN. These findings suggest that Fyn is involved in the mechanism of circadian oscillation and morphological formation of the SCN. The mechanism of the implication of Fyn discussed with the Fyn's roles in neural network formation and cellular signal transduction pathway.

Animals↗

PubMed2000

Crystal structure of the ffh and EF-G binding sites in the conserved domain IV of Escherichia coli 4.5S RNA.

BACKGROUND: Bacterial signal recognition particle (SRP), consisting of 4.5S RNA and Ffh protein, plays an essential role in targeting signal-peptide-containing proteins to the secretory apparatus in the cell membrane. The 4.5S RNA increases the affinity of Ffh for signal peptides and is essential for the interaction between SRP and its receptor, protein FtsY. The 4.5S RNA also interacts with elongation factor G (EF-G) in the ribosome and this interaction is required for efficient translation. RESULTS: We have determined by multiple anomalous dispersion (MAD) with Lu(3+) the 2.7 A crystal structure of a 4.5S RNA fragment containing binding sites for both Ffh and EF-G. This fragment consists of three helices connected by a symmetric and an asymmetric internal loop. In contrast to NMR-derived structures reported previously, the symmetric loop is entirely constituted by non-canonical base pairs. These pairs continuously stack and project unusual sets of hydrogen-bond donors and acceptors into the shallow minor groove. The structure can therefore be regarded as two double helical rods hinged by the asymmetric loop that protrudes from one strand. CONCLUSIONS: Based on our crystal structure and results of chemical protection experiments reported previously, we predicted that Ffh binds to the minor groove of the symmetric loop. An identical decanucleotide sequence is found in the EF-G binding sites of both 4.5S RNA and 23S rRNA. The decanucleotide structure in the 4.5S RNA and the ribosomal protein L11-RNA complex crystals suggests how 4.5S RNA and 23S rRNA might interact with EF-G and function in translating ribosomes.

Bacterial Proteins↗

PubMed2000

Transmembrane phosphoprotein Cbp regulates the activities of Src-family tyrosine kinases.

The Src family of protein tyrosine kinases (Src-PTKs) is important in the regulation of growth and differentiation of eukaryotic cells. The activity of Src-PTKs in cells of different types is negatively controlled by Csk, which specifically phosphorylates a conserved regulatory tyrosine residue at the carboxy-terminal tail of the Src-PTKs. Csk is mainly cytoplasmic and Src-PTKs are predominantly membrane-associated. This raises a question about the mechanism of interaction between these enzymes. Here we present Cbp--a transmembrane phosphoprotein that is ubiquitously expressed and binds specifically to the SH2 domain of Csk. Cbp is involved in the membrane localization of Csk and in the Csk-mediated inhibition of c-Src. In the plasma membrane Cbp is exclusively localized in the GM1 ganglioside-enriched detergent-insoluble membrane domain, which is important in receptor-mediated signalling. These findings reveal Cbp as a new component of the regulatory mechanism controlling the activity of membrane-associated Src-PTKs.

Amino Acid Sequence↗

PubMed2000

Involvement of FK506-sensitive and insensitive granule exocytosis pathways in perforin-dependent target cell lysis mediated by a CD8+ CTL clone.

The release of granzyme A and B through granule exocytosis by CD8+ CTL clone OE4 upon T cell receptor (TCR) activation was blocked by FK506 in a dose-dependent manner (IC50 = 3 nM), whereas a significant granzyme release was still detectable even in the presence of excess FK506. In contrast, the production of IFN-gamma was highly sensitive to FK506 (IC50 = 0.01 nM) and could be completely blocked by FK506. Both FK506-sensitive and insensitive granule exocytosis pathways were involved in the actual perforin-dependent killing toward different target cells. The combination of ionomycin and phorbol ester was able to mimic TCR stimulation to induce IFN-gamma production, although the same treatment triggered granule exocytosis inefficiently. Granule exocytosis and IFN-gamma production following TCR activation were profoundly prevented by calphostin C. Thus, these results demonstrate that the granule exocytosis pathway in this CD8+ CTL clone depends on the activation of protein kinase C, and requires either calcineurin-dependent or independent additional signals downstream of TCR activation.

Animals↗

PubMed2000

RNA-binding proteins: TRAPping RNA bases.

In Bacillus subtilis, tryptophan biosynthesis is regulated by a mechanism called attenuation. The new crystal structure of the 'trp RNA binding attenuation protein', TRAP, in complex with RNA has provided new structural insights into how proteins can bind RNA to regulate transcription and translation.

Bacillus subtilis↗

PubMed2000

The fungal metabolite gliotoxin: immunosuppressive activity on CTL-mediated cytotoxicity.

Gliotoxin, a potential etiologic agent which is synthesized by Aspergillus fumigatus and other pathogenic fungi, exhibits a variety of immunosuppressive activities. We have found that gliotoxin markedly inhibits both perforin-dependent and Fas ligand-dependent cytotoxic T-lymphocyte (CTL)-mediated cytotoxicity. Gliotoxin blocked granule exocytosis and the production of inositol phosphates in response to anti-CD3 stimulation. Apparently, activation signals were not efficiently received by the gliotoxin-treated CTL clone, perhaps because gliotoxin profoundly disturbed CTL cell attachment to immobilized anti-CD3. Although the expression of surface molecules of the CTL clone such as CD3 was unaffected by gliotoxin, the effector/target conjugate formation was inhibited dose-dependently by gliotoxin treatment of the effector CTL clone. These results suggest that gliotoxin prevents CTL from interacting with target cells.

Animals↗

PubMed2000

Quenched light hadron spectrum

We present results of a large-scale simulation for the flavor nonsinglet light hadron spectrum in quenched lattice QCD with the Wilson quark action. Hadron masses are calculated at four values of lattice spacing in the range a approximately 0.1-0.05 fm on lattices with a physical extent of 3 fm at five quark masses corresponding to m(pi)/m(rho) approximately 0.75-0.4. The calculated spectrum in the continuum limit shows a systematic deviation from experiment, though the magnitude of deviation is contained within 11%. Results for decay constants and light quark masses are also reported.

Journal Article↗

PubMed2000

Changes of alpha1-acid glycoprotein microheterogeneity in acute inflammation stages analyzed by isoelectric focusing using serum obtained postoperatively.

The relationship between variations of alpha1-acid glycoprotein (orosomucoid, AGP) microheterogeneity detected from isoelectric focusing (IEF) patterns and clinical stage of acute inflammation based on serum C-reactive protein (CRP) levels and interleukin-6 (IL-6) levels was investigated. Serum samples were obtained from healthy subjects, and from patients with esophageal or stomach carcinoma before and after operation. Samples without neuraminidase treatment were used for AGP microheterogeneity analysis, and samples with neuraminidase treatment for AGP heterogeneity analysis. In AGP microheterogeneity, nine bands were detected in the range of pI 3.18-3.57 in sera obtained from healthy subjects. In patients, AGP microheterogeneity changed the first day after operation; the percentage of bands surrounding pI 3.5 increased, and the highest value appeared in sera taken the first or second day after operation and then decreased quickly. These bands showed reactivity for concanavalin A (Con A). The increase in Con A-reactive AGP occurred later than the increase in IL-6, and occurred earlier than the increase in CRP. On the seventh day after operation, the percentage of bands around pI 3.2 increased. These bands showed the reactivity for Datura stramonium agglutinin. On the other hand, in samples with neuraminidase treatment, little change of AGP heterogeneity was observed in most samples, which did not reflect the stage of inflammation. These findings suggested that AGP microheterogeneity detection was a useful marker for the clinical stage of inflammation.

Aged↗

PubMed2000

Thymic carcinoma. Outcome of treatment including surgical resection.

OBJECTIVE: Thymic carcinoma is treated by the same guidelines used for thymoma, despite having a more aggressive histologic appearance and clinical course. METHOD: To evaluate the outcome of treatment, patients undergoing treatment including surgery at the National Cancer Center Hospital East were reviewed and reported with descriptions of postoperative pathologic stages based on Masaoka staging. RESULTS: Six Japanese patients--2 men and 4 women with a median age of 59 years (range: 23-67)--underwent treatment, including surgery. The histologic type of tumor was squamous cell carcinoma in 4, 1 of which was associated with invasive thymoma; adenosquamous carcinoma associated with thymoma in 1; and lymphoepithelioma-like carcinoma in 1. Four of the 6 patients survived--2 stage II were alive and well with no evidence of disease 69 months and 44 months after surgery; 1 stage III was alive with the disease 44 months after preoperative chemotherapy and subsequent surgery; and 1 stage III was alive with multiple pulmonary metastases 17 months after surgery. A stage IVa died of the tumor 48 months after preoperative chemotherapy and subsequent surgery, while 1 stage III died of the tumor 35 months after surgery. CONCLUSION: The outcome of thymic carcinoma treatment must be reported using the same histologic typing and staging. Further study is warranted to define precise treatment strategy for this disease.

Adult↗

PubMed2000

Combined partial sternectomy for thymic carcinoma.

For thymic carcinoma, a 67-year-old Japanese female underwent combined chemotherapy, to which a partial response was registered. Afterwards, total thymectomy with combined en bloc resection of the biopsy site, the partial sternum and the partial mediastinal components were completed with a clear margin. Skeletal reconstruction was performed using polypropylene mesh. Paradoxical movement of the chest wall was tolerable. Functional and cosmetic appearance of the chest wall following the reconstruction was satisfactory. Thirty-nine months had passed since the onset of the chemotherapy, when local recurrence was detected in the approximated major pectoral muscle. The patient underwent salvage radiation therapy that resulted in a complete response, and is currently alive and disease free at 46 months after the onset of the combined chemotherapy.

Aged↗

PubMed2000

Sodium nitroprusside-induced seizure and taurine release from rat hippocampus.

We have recently reported that the nitric oxide (NO) donor, sodium nitroprusside (SNP), induces seizures which are associated with an increase in the basal release of aspartate and glutamate from rat hippocampus (Kaku et al., 1998). In order to determine whether taurine release occurs with SNP-induced seizures, we examined the effects of NO-related compounds, i.e., the NO trapper, diethyldithiocarbamate (DETC), the superoxide radical scavenger, dithiothreitol (DTT), the xanthine oxidase inhibitor, oxypurinol and the guanylyl cyclase inhibitor, 1H-(1,2,4)oxadiazole(4,3-a)quinoxalin-1-one (ODQ), on SNP-induced seizures and in vivo taurine release from rat hippocampus using microdialysis. Perfusion with 0.5mM SNP provoked seizures and significantly increased taurine release, with the increase in release occurring primarily during reperfusion with artificial cerebrospinal fluid lacking SNP. Perfusion with 5mM DETC significantly abolished the SNP-induced seizures and reduced taurine release during and after perfusion with the drugs. Perfusion with 1mM DTT significantly reduced both the frequency of the SNP-induced seizures and taurine release during and after perfusion with the drugs. Perfusion with 1 mM oxypurinol or 0.5 mM ODQ did not reduce the frequency of the SNP-induced seizures, but tended to decrease taurine release during and after perfusion with the drugs. These results demonstrate that SNP-induced seizures are triggered by an increase in both NO and peroxynitrite and are related to an increase in taurine release from rat hippocampus.

Animals↗

PubMed2000

Prognostic significance of the size of central fibrosis in peripheral adenocarcinoma of the lung.

BACKGROUND: The prognostic significance of the characteristics of central fibrosis in peripheral adenocarcinoma of the lung has been reported. However, the prognostic significance of the size of central fibrosis has never been evaluated. METHODS: A total of 100 consecutive surgically resected peripheral adenocarcinomas of the lung measuring 3.0 cm or less in maximum dimension were reviewed histologically, and the maximum dimension of central fibrosis was measured on conventional hematoxylin and eosin stain. RESULTS: Median follow-up for patients alive was 54 months. The overall 5-year survival rate was 75%. Twenty-one patients with adenocarcinoma having central fibrosis 5 mm or smaller in maximum dimension had a 5-year survival rate of 100%, whereas the other 79 patients had a 5-year survival less than 70%. Multivariate analysis showed the size of central fibrosis to be an independent prognostic factor as significant as vascular invasion and locoregional lymph node metastasis (p = 0.010, 0.024, and 0.024, respectively). CONCLUSIONS: The size of central fibrosis is an independent prognostic factor in peripheral lung adenocarcinoma, as significant as the well-established prognostic factors vascular invasion and lymph node metastasis.

Adenocarcinoma↗

PubMed2000

Absolute number of circulating CD34+ cells is abnormally low in refractory anemias and extremely high in RAEB and RAEB-t; novel pathologic features of myelodysplastic syndromes identified by highly sensitive flow cytometry.

We scored absolute numbers of circulating CD34+ cells by a highly sensitive triple-color flow cytometric analysis using CD45 monoclonal antibody, CD34 monoclonal antibody and propidium iodide. Forty-one patients with MDS (RA: 27, RARS: 1, RAEB: 6, RAEB-t: 3,CMML: 4), 12 patients with aplastic anemia (AA) and 36 age-adjusted normal subjects were studied. RA had significantly decreased numbers of cells expressing CD34 (0.21 +/- 0.29 x 10(6)/l) compared with normal subjects (0.81 +/- 0.36 x 10(6)/l)(P < 0.001). This low number of CD34+ cells in RA resembles the case of AA (0.39 +/- 0.73 x 10(6)/l). In light-scatter analysis, the CD34+ cells of RA patients were distributed mainly in low forward scatter (FSC) (lymphocyte region). In contrast, the CD34+ cell counts were extremely high in patients with RAEB (46.54 +/- 71.37 x 10(6)/l) and RAEB-t (57.00 +/- 52.36 x 10(6)/l) (P < 0.001) and the CD34+ cells were observed in high FSC (blast region).CMML patients showed moderately increased numbers of CD34+ cells (3.69 +/- 4.64 x 10(6)/l). Thus, there was a distinct difference in cell size and number of circulating CD34+ cells between RA and RAEB/RAEB-t. In univariate and multivariate analysis, a high CD34+ cell count (> or = 1.0 x 10(6)/l) was a poor prognostic factor. This method allows one to distinguish RA from other MDS subtypes more reliably than by morphology alone and provides early signs of progression to acute leukemia.

Adult↗