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Biomedical subjects

Y Ishikawa

Publications and source records attributed to Y Ishikawa.

At least 19 recordsLinked to original sources
PubMed2001

Characterization of the stromal protease(s) degrading the cross-linked products of the D1 protein generated by photoinhibition of photosystem II.

When photosystem (PS) II-enriched membranes are exposed to strong light, cross-linking of the intrinsic D1 protein with the surrounding polypeptides and degradation of the D1 protein take place. The cross-linking of the D1 protein with the alpha-subunit of cytochrome b(559) is suggested to be an early event of photoinduced damage to the D1 protein (Barbato et al., FEBS Lett. 309 (1992) 165-169). The relationship between the cross-linking and the degradation of the D1 protein, however, is not yet clear. In the present study, we show that the addition of stromal extract from chloroplasts degrades the 41 kDa cross-linked product of D1/cytochrome b(559) alpha-subunit and enhances the degradation of the D1 protein. Incubation of the preilluminated PS II-enriched membranes with the stromal extract at 25 degrees C causes the degradation of the cross-linked product by more than 70%. The activity of the stromal extract showed a pH optimum at 8.0, and was enhanced by the addition of ATP or GTP. Consistent with the nucleotide effect, this stromal activity was eliminated by the preincubation of the stromal extract with apyrase, which hydrolyzes nucleotides. Also, the stromal activity was nearly fully inhibited by a serine-type protease inhibitor, 3,4-dichloroisocoumarin, which suggests participation of a serine-type protease(s).

Apyrase↗
PubMed2001

In situ pedicle resection in left trisegmentectomy of the liver combined with reconstruction of the right hepatic vein to an inferior vena caval segment transpositioned from the infrahepatic portion.

A combination of an in situ pedicle resection of the liver and a hepatic vein reconstruction using a cranially transpositioned segment of the IVC after implantation of an ePTFE graft at the missing IVC was useful in treating a patient who suffered from a huge liver tumor involving all of the hepatic venous confluence and the IVC. Although early tumor recurrence remains an unresolved problem for such patients, a surgical approach is feasible. This technique can be justified as a therapeutic modality, not only because it improves quality of life, but also because it provides patients with an opportunity for additional treatment.

Anastomosis, Surgical↗
PubMed2001

Wide distribution of the MICA-MICB null haplotype in East Asians.

Stress-inducible MICA (MHC class I chain-related A) is known to bind to NKG2D, which is one of the natural killer (NK) cell receptors, and plays a role in immune surveillance. We have reported that a MICA-MICB null haplotype is in linkage disequilibrium with HLA-B*4801 in the Japanese population. In the haplotype, an approximately 100-kb deletion, including the entire MICA gene, was observed and MICB possessed a premature stop codon. In this study, a multiplex polymerase chain reaction (PCR) method was developed for detecting the MICA deletion. MICB alleles were typed by PCR-single-strand conformation polymorphism (SSCP) method and direct sequencing. The frequency of the MICA-MICB null haplotype was 3.7% on the average, and was strongly associated with HLA-B48 in seven East Asian populations. It was presumed that the stop codon of MICB gene generated after the large-scale deletion. The wide distribution of the null haplotype at polymorphic frequencies suggests that the haplotype has been conservatively maintained because of some selective advantage.

Alleles↗
PubMed2001

[Carinal resection for bronchogenic carcinoma].

The purpose of this study was to evaluate the results of carinal resection for bronchogenic carcinoma in our institute. From 1981 to 1999, 24 carinal resection were performed for squamous cell carcinoma (n = 19), adenoid cystic carcinoma (n = 2), small cell carcinoma (n = 1), adenocarcinoma (n = 1), and mucoepidermoid carcinoma (n = 1). Nineteen underwent sleeve pneumonectomy, 2 had carinal resection without lung resection, 2 had carinal resection with right middle and lower lobectomy, and 1 had wedge pneumonectomy. In the patients with sleeve or wedge pneumonectomy, there were 5 operative death and 3 patients had survived for more than 3 years. Two patients with low-grade malignant tumors underwent carinal resection without lung resection and survived more than 10 years. We believe that limited carinal resection for low-grade malignant tumors are safe and valuable procedure. Careful selection of patients with sleeve or wedge pneumonectomy is mandatory.

Adult↗
PubMed2001

[A case of squamous cell carcinoma of the bladder that was successfully treated with multidisciplinary therapies].

A 45-year-old man with hematopyuria detected at another hospital visited our department for further examination. Endoscopic examination revealed a disintegration abscess between the bladder neck and prostatic urethra. Transurethral biopsy demonstrated squamous cell carcinoma of the bladder. He received 40 Gy of radiation combined with M-VAC (methotrexate, vinblastine, dovorubicin cisplatin) chemotherapy. Pathologically, a complete response was found when he underwent total cystourethrectomy. There has been no sign of recurrence for one and a half years postoperatively.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed2000

Bioflavonoid quercetin inhibits mitosis and apoptosis of glomerular cells in vitro and in vivo.

Bioflavonoids have been regarded as therapeutic agents for a wide range of disease including inflammation. In this report, we investigated effects of bioflavonoid quercetin on mitosis and apoptosis of glomerular cells in vitro and in vivo. Serum-stimulated rat mesangial cells were treated with or without quercetin, and total cell number, percentages of mitotic cells, and incorporation of [(3)H]-thymidine were evaluated. All three assays showed that mitogenic activity of mesangial cells was markedly attenuated by quercetin. To examine the effect of quercetin on apoptosis, mesangial cells were pretreated with or without quercetin and stimulated by hydrogen peroxide or tumor necrosis factor-alpha. Hoechst staining and DNA ladder assay showed that both apoptotic responses were dramatically inhibited by quercetin. We further investigated effects of quercetin on in vivo mitosis and apoptosis of glomerular cells. Rats were administered with or without quercetin intraperitoneally, and nephrotoxic serum nephritis was induced. Immunohistochemical analyses showed that treatment with quercetin significantly reduced the number of proliferating cell nuclear antigen (+) cells and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (+) cells in the glomerulus. These data suggested that quercetin has the potential for inhibiting mitosis and apoptosis of glomerular cells both in vitro and in vivo.

Animals↗
PubMed2000

p38 mitogen-activated protein kinase regulates low potassium-induced c-Jun phosphorylation and apoptosis in cultured cerebellar granule neurons.

Cultured rat cerebellar granule neurons are widely used as a model system for studying neuronal apoptosis. After maturation by culturing in medium containing 26 mm potassium (high K(+)), changing to medium containing 5 mm potassium (low K(+); LK) rapidly induces neuronal apoptosis. Then over 50% of granule cells die within 24 h. However, the molecular mechanisms by which the LK-induced apoptosis occurs in cultured cerebellar granule cells remain unclear. In the present study, we found that p38 MAP kinase (p38) was an important factor for LK-induced apoptosis. Three hours after changing to LK medium, p38 was markedly activated. In addition, SB203580, a specific inhibitor of p38, strongly inhibited the phosphorylation and expression of c-Jun in LK-induced apoptosis of cultured cerebellar granule cells. In vitro kinase assay using glutathione S-transferase-c-Jun as a substrate showed that p38 directly phosphorylated c-Jun. Furthermore, in the presence of SB203580, about 80% of neurons survived. These results indicate that p38 regulates LK-induced apoptosis of cerebellar granule neurons.

Animals↗
PubMed2000

Prognostic value of genetically diagnosed lymph node micrometastasis in non-small cell lung carcinoma cases.

The predictive value of lymph node micrometastasis, detected by immunohistochemical or genetic methods, is well appreciated in terms of prognosis. However, a major problem is high false-positive rates, because most methods focus on cytokeratin, which is a component not only of carcinoma but also normal epithelial and nonepithelial cells. Mutant allele-specific amplification (MASA) can detect DNAs derived from cancer cells itself, reportedly with high sensitivity. It was, therefore, used with nested-PCR using p53 or K-ras mutation for analysis of lymph node micrometastasis in non-small cell lung carcinoma (NSCLC) patients in the present study, in comparison with the immunohistochemical method using an anti-cytokeratin reagent for the same samples. Lymph nodes from 31 NSCLC patients with p53 and K-ras mutated tumors (30 and 1, respectively) staged as pathological (p)-T1-4 N0-1 and M0 were examined. Genetic and immunohistochemical methods demonstrated positive reactions in 34 (15%) and 61 (27%) of 229 lymph nodes, respectively (9 cases, 29%, and 24 cases, 77%). The concordance with the two methods was 77%, but 13 (39%) of 34 genetically positive lymph nodes could not be detected by immunohistochemistry (IHC). Of 22 cases with p-N0 disease, 6 (27%) were genetically positive in hilar and/or mediastinal lymph nodes, and 4 (67%) of them died after cancer relapse. In contrast, none of the patients without micrometastasis died of cancer (P < 0.001, log rank analysis). Of the same p-N0 patients, 17 (77%) were positive by IHC, and 4 (24%) of them died of cancer, whereas 5 negative patients did not suffer cancer relapse. Survival did not significantly differ between cases positive and negative (P = 0.246) by IHC. According to the g-N (N factor restaged by a genetic method), patients with g-N1 and g-N2 disease had a shorter survival than those with g-N0 disease (P = 0.042 and P < 0.001, respectively). However, no significant difference was observed with grading by IHC. Thus, detection of micrometastasis in regional lymph nodes with the MASA method, in other words with a carcinoma-specific marker, is of greater prognostic significance for early stage NSCLC patients than immunohistochemical results. This approach should facilitate selection of patients for whom postoperative adjuvant chemotherapy should be performed.

Adenocarcinoma↗
PubMed2000

NAD(P)+-NAD(P)H models. 90. Stereoselection controlled by electronic effect of a carbonyl group in oxidation of NAD(P)H analog.

4-Monodeuterated NAD(P)H model compounds (1,4,6,7-tetrahydro-1,6,11-trimethyl-5-oxo-5H-benzo[c]pyrido[2,3-e]az epin; 11Me-MMPAH) have been oxidized with a series of p-benzoquinone and its derivatives in the presence of Mg2+. The models have an axial chirality with respect to the orientation of carbonyl dipole, the dihedral angle of which is larger than 55 degrees out of the plane of dihydropyridine ring. Without Mg2+, the anti- (with respect to the carbonyl dipole) hydrogen is 3 to 32 times more reactive than the corresponding syn-hydrogen, whereas, when Mg2+ is present in the system, the selectivity is shifted toward the syn-preferency. Mg2+ plays the role of a Lewis acid catalyst to control the stereochemistry at the same time as it catalyzes the reaction.

Catalysis↗
PubMed2000

Effects of hypoxia on cholesterol metabolism in human monocyte-derived macrophages.

We assessed the metabolism of low density lipoprotein (LDL) of human monocyte-derived macrophages under hypoxia. The specific binding and association of 125I-labeled LDL (125I-LDL) were not changed under hypoxia compared to normoxia. However, the degradation of 125I-LDL under hypoxia decreased to 60%. The rate of cholesterol esterification under hypoxia was 2-fold greater on incubation with LDL or 25-hydroxycholesterol. The cellular cholesteryl ester content was also greater under hypoxia on incubation with LDL. Secretion of apolipoprotein E into the medium was not altered under hypoxia, suggesting that apolipoprotein E independent cholesterol efflux may be reduced under hypoxia. Thus, hypoxia affects the intracellular metabolism of LDL, stimulates cholesterol esterification, and enhances cholesteryl ester accumulation in macrophages. Hypoxia is one of the important factors modifying the cellular lipid metabolism in arterial wall.

Apolipoproteins E↗
PubMed2000

Introduction of a foreign gene into medakafish using the particle gun method.

We developed a procedure to introduce a foreign gene into fertilized eggs of medakafish (Oryzias latipes) using the particle gun method, which is one of the easiest and most reliable techniques for gene transfer. A plasmid construct with the green fluorescence protein (GFP) gene driven by the madakafish beta-actin gene promoter was successfully introduced into eggs, and the expression of GFP was observed in 20% of the primary transfectant (chimera) fish. In addition, germ line transmission of GFP was observed in 13% of the GFP-positive primary transfectant fish. The new application described here should enable us to investigate gene expression using the fish model on a routine basis without high technical sophistication. J. Exp. Zool. 287:285-293, 2000.

Animals↗
PubMed2000

Persistent increase in the amount of aquaporin-5 in the apical plasma membrane of rat parotid acinar cells induced by a muscarinic agonist SNI-2011.

SNI-2011 induces the long-lasting increase in the amount of aquaporin-5 (AQP5) in apical plasma membranes (APMs) of rat parotid acini in a concentration-dependent manner. This induction was inhibited by p-F-HHSiD, U73122, TMB-8, or dantrolene but not by bisindolmaleimide or H-7, indicating that SNI-2011 acting at M(3) muscarinic receptors induced translocation of AQP5 via [Ca(2+)](i) elevation but not via the activation of protein kinase C. In contrast, acetylcholine induced a transient translocation of AQP5 to APMs. SNI-2011 induces long-lasting oscillations of [Ca(2+)](i) in the presence of extracellular Ca(2+). Thus, SNI-2011 induces a long-lasting translocation of AQP5 to APMs coupled with persistent [Ca(2+)](i) oscillations.

Animals↗
PubMed2000

Analysis of human V alpha 24+ CD4+ NKT cells activated by alpha-glycosylceramide-pulsed monocyte-derived dendritic cells.

Human V alpha 24+ NKT cells with an invariant TCR (V alpha 24-J alpha Q) have been shown to be specifically activated by synthetic glycolipids such as alpha-galactosylceramide and alpha-glucosylceramide in a CD1d-restricted and V alpha 24 TCR-mediated manner. We recently characterized V alpha 24+ CD4- CD8- double negative (DN) NKT cells using alpha-galactosylceramide-pulsed monocyte-derived dendritic cells. Here, we compare V alpha 24+ CD4+ NKT cells with human V alpha 24+ DN NKT cells from the same donor using alpha-galactosylceramide-pulsed monocyte-derived dendritic cells. Human V alpha 24+ CD4+ NKT cells were phenotypically and functionally similar to the human V alpha 24+ DN NKT cells characterized previously. Both of them use V alpha 24-J alpha Q-V beta 11 TCR and express CD161 (NKR-P1A), but not the other NK receptors tested so far. They also produce cytokines such as IL-4 and IFN-gamma, and, in regard to IL-4 production, V alpha 24+ CD4+ NKT cells produce more IL-4 than V alpha 24+ DN NKT cells. The cells exhibit marked cytotoxic activity against the U937 tumor cell line, but not against the NK target cell line, K562. Although at least some of the factors responsible for the stimulation of V alpha 24+ NKT cells have been clarified, little is known regarding the killing phase of these cells. Here we show that the cytotoxic activity of V alpha 24+ NKT cells against U937 cells is mediated mainly through the perforin pathway and that ICAM-1/LFA-1 as well as CD44/hyaluronic acid interactions are important for the effector phase of V alpha 24+ NKT cell-mediated cytotoxicity against U937 cells.

Antigens, CD1↗
PubMed2000

Selective involvement of superoxide anion, but not downstream compounds hydrogen peroxide and peroxynitrite, in tumor necrosis factor-alpha-induced apoptosis of rat mesangial cells.

Tumor necrosis factor-alpha (TNF-alpha) induces reactive oxygen species (ROS) that serve as second messengers for intracellular signaling. Currently, precise roles of individual ROS in the actions of TNF-alpha remain to be elucidated. In this report, we investigated the roles of superoxide anion (O-(2)), hydrogen peroxide (H(2)O(2)), and peroxynitrite (ONOO(-)) in TNF-alpha-triggered apoptosis of mesangial cells. Mesangial cells stimulated by TNF-alpha produced O-(2) and underwent apoptosis. The apoptosis was inhibited by transfection with manganese superoxide dismutase or treatment with a pharmacological scavenger of O-(2), Tiron. In contrast, although exogenous H(2)O(2) induced apoptosis, TNF-alpha-triggered apoptosis was not affected either by transfection with catalase cDNA or by treatment with catalase protein or glutathione ethyl ester. Similarly, although ONOO(-) precursor SIN-1 induced apoptosis, treatment with a scavenger of ONOO(-), uric acid, or an inhibitor of nitric oxide synthesis, N(G)-nitro-L-argininemethyl ester hydrochloride, did not affect the TNF-alpha-triggered apoptosis. Like TNF-alpha-induced apoptosis, treatment with a O-(2)-releasing agent, pyrogallol, induced typical apoptosis even in the concurrent presence of scavengers for H(2)O(2) and ONOO(-). These results suggested that, in mesangial cells, TNF-alpha induces apoptosis through selective ROS. O-(2), but not H(2)O(2) or ONOO(-), was identified as the crucial mediator for the TNF-alpha-initiated, apoptotic pathway.

Animals↗