Biomedical subjects

M Kato

Publications and source records attributed to M Kato.

At least 451 records · Page 25Linked to original sources

PubMed1999

Detection of cerebroside sulfotransferase mRNA in human gastric mucosa and adenocarcinoma.

Sulfatide is a major acidic glycolipid in human gastric mucosa, and its sulfation is catalyzed by cerebroside sulfotransferase (CST). To investigate the expression of the CST gene in human gastric cancer, a reverse transcription PCR method was developed with the use of endoscopic bioptic specimens. By this method, we examined the CST mRNA expression in 11 cases of gastric cancer, and in all the cases we detected various levels of the expression both in cancer tissues and in uninvolved adjacent tissues. The present assay method was suggested to be useful in the detection of CST mRNA from a limited amount of bioptic samples.

Adenocarcinoma↗

PubMed1999

Tissue distribution of placenta-type 6-phosphofructo- 2-kinase/fructose-2,6-bisphosphatase.

Several isozymes of 6-phosphofructo-2-kinase/fructose-2, 6-bisphosphatase have been characterized from mammalian tissues and, based on tissue origin, they are classified as liver, skeletal muscle, heart, testis, and placenta isozymes. In this paper, we examined the tissue distribution of placenta-type isozyme in rat tissues at the levels of transcription and translation. Analysis by Northern blotting showed that placenta, brain, testis, liver, kidney, and skeletal muscle expressed mRNA of placenta-type isozyme. Western blot analysis of fractions from POROS-HQ column chromatography of extracts from various rat tissues showed that proteins of placenta-type isozyme are expressed in placenta, brain, testis, liver, spleen, heart and lung, but not in kidney and skeletal muscle. An immunohistochemical study showed that, in liver, placenta-type isozyme is localized in Kupffer cells. These results indicate that isozymes of this particular enzyme may occur in particular cell types within each tissue.

Animals↗

PubMed1999

Effective control of Epstein-Barr virus-related hemophagocytic lymphohistiocytosis with immunochemotherapy. Histiocyte Society.

The familial form of hemophagocytic lymphohistiocytosis (HLH) is a lethal disorder. Although the prognosis for Epstein-Barr virus-associated HLH (EBV-HLH) remains uncertain, numerous reports indicate that it can also be fatal in a substantial proportion of cases. We therefore assessed the potential of immunochemotherapy with a core combination of steroids and etoposide to control EBV-HLH in 17 infants and children who met stringent diagnostic criteria for this reactive disorder of the mononuclear phagocyte system. Treatment of life-threatening emergencies was left to the discretion of participating investigators and typically included either intravenous Ig or cyclosporin A (CSA). Five patients (29%) entered complete remission during the induction phase (1 to 2 months), whereas 10 others (57%) required additional treatment to achieve this status. In 2 cases, immunochemotherapy was ineffective, prompting allogeneic bone marrow transplantation. Severe but reversible myelosuppression was a common finding; adverse late sequelae were limited to epileptic activity in one child and chronic EBV infection in 2 others. Fourteen of the 17 patients treated with immunochemotherapy have maintained their complete responses for 4+ to 39+ months (median, 15+ months), suggesting a low probability of disease recurrence. These results provide a new perspective on EBV-HLH, showing effective control (and perhaps cure) of the majority of EBV-HLH cases without bone marrow transplantation, using steroids and etoposide, with or without immunomodulatory agents.

Child↗

PubMed1999

Apoptotic photoreceptor cell death induced by quinolone phototoxicity in mice.

We examined retinal degeneration induced by phototoxicity of quinolone antibacterial agents. Albino Balb/c and pigmented DBA/2 mice fasted overnight were given a single oral administration of ciprofloxacin (CPFX), levofloxacin (LVFX), enoxacin (ENX), lomefloxacin (LFLX) or sparfloxacin (SPFX), followed by ultraviolet-A (UVA) irradiation at 1.5 mW/cm2 for 4 h (21.6 J/cm2). At 24 h after quinolone administration, the mice were sacrificed, and the eyes were then histologically examined. ENX or LFLX at 200 or 400 mg/kg or SPFX at 50 or 100 mg/kg plus UVA induced retinal degeneration in Balb/c mice, whereas no histological change was observed in the eyes of DBA/2 mice. CPFX and LVFX at 800 mg/kg plus UVA had no effect on the eyes in either Balb/c or DBA/2 mice. Agarose gel electrophoresis showed that chromosomal DNA extracted from the eyes of Balb/c mice was fragmented in the SPFX 100 mg/kg group, but not in the LVFX 800 mg/kg group. In the electron microscopic examination, swelling of mitochondria and disruption of the cytoplasm were observed in the photoreceptor inner segment (PIS) at 2 h, and disarrangement of lamellar disks in the outer segment (POS) and condensed chromatin in photoreceptor cell nuclei in the outer nuclear layer (ONL) were observed at 4 h after 100 mg/kg SPFX administration to Balb/c mice. These results suggest that quinolone plus UVA irradiation induces retinal degeneration in albino Balb/c mice, but not in DBA/2 mice, and this degeneration is associated with apoptotic photoreceptor cell death.

4-Quinolones↗

PubMed1999

Nonpeptide small-molecular inhibitors of dipeptidyl peptidase IV: N-phenylphthalimide analogs.

A novel series of nonpeptide small-molecular dipeptidyl peptidase IV (DPP-IV) inhibitors with an N-phenylphthalimide skeleton has been developed. Some of the compounds, including 4-amino-(2,6-dimethylphenyl)phthalimides (7), 4- and 5-hydroxy-(2,6-diethylphenyl)phthalimide (11 and 14), 4-hydroxy-(2,6-diisopropylphenyl)phthalimide (12), and thiocarbonyl analogs of (2,6-diisopropylphenyl)phthalimide and their 4,5,6,7-tetrafluorinated derivative (18, 19 and 20), were more potent than the well-known DPP-IV-specific inhibitor, Pro-boroPro (PBP). Among them, 18 was revealed to be a DPP-IV-specific inhibitor, while the others also showed inhibitory activity toward another peptidase, aminopeptidase N (APN).

Cell Line↗

PubMed1999

Characterization of six cell lines established from human pancreatic adenocarcinomas.

BACKGROUND: Six human pancreatic carcinoma cell lines, designated as KMP-1 to KMP-6, were established and maintained in vitro for > 3 years. All were derived from pancreatic ductal adenocarcinomas. The six cell lines originated from either primary pancreatic tumors, metastatic liver tumors, or metastases to lymph nodes. METHODS: Each cell line was characterized by its morphology, doubling time, colony forming efficiency (CFE) on plastic dishes, tumorigenicity in nude mice, chromosomal analysis, and the amount of tumor markers secreted into the culture medium. Furthermore, mutations in the K-ras, p53, and p16/INK4a genes were analyzed. RESULTS: All cell lines grew as an adhering monolayer and were cultured in medium supplemented with 2% fetal bovine serum. The doubling time ranged from 16-70 hours, and the CFE ranged from 0.1-11%. Subcutaneous transplantation of these carcinoma cells into nude mice resulted in the formation of tumors. Chromosomal analysis showed that the modal numbers ranged from 43-124, and each karyotype was unique. Each cell line secreted detectable amounts of squamous cell carcinoma antigen, carcinoembryonic antigen, carbohydrate antigen 19-9, Dupan-II, and cytokeratin 19 fragment, respectively. Genetic alterations of the K-ras, p53, and p16 genes were detected in six, three, and five, respectively, of the six cell lines. CONCLUSIONS: The authors believe that these newly established pancreatic carcinoma cell lines will contribute to wide ranging studies regarding pancreatic carcinoma progression.

Adenocarcinoma↗

PubMed1999

Crystal structure of neuropsin, a hippocampal protease involved in kindling epileptogenesis.

Neuropsin is a novel serine protease, the expression of which is highly localized in the limbic areas of the mouse brain and which is suggested to be involved in kindling epileptogenesis and hippocampal plasticity. The 2.1-A resolution crystal structure of neuropsin provides the first three-dimensional view of one of the serine proteases highly expressed in the nervous system, and reveals a serine protease fold that exhibits chimeric features between trypsin and nerve growth factor-gamma (NGFgamma), a member of the kallikrein family. Neuropsin possesses an N-glycosylated "kallikrein loop" but forms six disulfide bonds corresponding to those of trypsin. The ordered kallikrein loop projects proline toward the active site to restrict smaller residues or proline at the P2 position of substrates. Loop F, which participates in forming the S3/S4 sites, is similar to trypsin rather than NGFgamma. The unique conformations of loops G and H form an S1 pocket specific for both arginine and lysine. These characteristic loop structures forming the substrate-binding site suggest the novel substrate specificity of neuropsin and give a clue to the design of its specific inhibitors.

Amino Acid Sequence↗

PubMed1999

Strong expression of glutathione S-transferase placental form in early preneoplastic lesions and decrease with progression in hamster buccal pouch carcinogenesis.

The objective of this work was to investigate the expression of glutathione S-transferase placental form (GST-P) in 9,10-dimethyl-1,2-benzanthracene (DMBA)-induced hamster buccal pouch carcinogenesis. Lesions were classified histopathologically into four categories, simple hyperplasia, papillary and nodular (PN) hyperplasia, papilloma and squamous cell carcinoma (SCC). Respective mean percentage GST-P positive areas were 81.6 +/- 7.3%, 76.1 +/- 7.3%, 25.8 +/- 4.9% and 1.9 +/- 1.2%, with significant (P < 0.001) differences confirmed between each of the lesions. These results indicate that GST-P is a useful positive marker for neoplastic lesions and that a decreased expression occurs with progression so that it may be predictive of future development of malignancy.

9,10-Dimethyl-1,2-benzanthracene↗

PubMed1999

Linkage between melanocytic tumor development and early burst of Ret protein expression for tolerance induction in metallothionein-I/ret transgenic mouse lines.

We examined the basis of the all or none difference in inducing melanocytic tumor development among three transgenic mouse lines (304, 192 and 242) to which the same promoter-enhancer (metallothionein-I) and oncogene (ret) were introduced. We initially demonstrated that both skin melanosis and Ret protein expression in skin, thymus and brain first became detectable before or immediately after birth in the mice of the tumor developing lines (304 and 192), whereas they became detectable a few days after birth in the mice of the non-tumor developing line (242) by Western blotting and immunohistochemical analysis. Interestingly, the Ret protein expression in skin developed rapidly after birth as a burst with peak levels on 0.5-1.5 day newborns of lines 304 and 192 and on 7.0-7.5 day-old mice of line 242. The levels of autophosphorylation of Ret kinase in skin were, however, invariable among these three transgenic mouse lines. The mice of line 242, but not those of lines 192 and 304, responded to Ret protein immunization by increased antigen-dependent lymphocyte proliferation and T-cell-mediated tumor growth suppression in vitro. Furthermore, ret-transgenic mice of line 242, but not line 304, rejected the subcutaneously transplanted tumors that had originally developed in a mouse of line 304. These results suggest that whether oncogene product-specific-tolerance is established or not to antitumor immunity may be decided by the dynamics of ret oncogene expression before and after delivery and this is the primary factor determining development or non-development of melanoma.

Animals↗

PubMed1999

Alternatively spliced variant of Smad2 lacking exon 3. Comparison with wild-type Smad2 and Smad3.

An alternatively spliced variant of Smad2 with a deletion of exon 3 (Smad2Deltaexon3) is found in various cell types. Here, we studied the function of Smad2Deltaexon3 and compared it with those of wild-type Smad2 containing exon 3 (Smad2(wt)) and Smad3. When transcriptional activity was measured using the p3TP-lux construct, Smad2Deltaexon3 was more potent than Smad2(wt), and had activity similar to Smad3. Transcriptional activation of the activin-responsive element (ARE) of Mix.2 gene promoter by Smad2Deltaexon3 was also similar to that by Smad3, and slightly less potent than that by Smad2(wt). Phosphorylation by the activated transforming growth factor-beta type I receptor and heteromer formation with Smad4 occurred to similar extents in Smad2Deltaexon3, Smad2(wt), and Smad3. However, DNA binding to the activating protein-1 sites of p3TP-lux was observed in Smad2Deltaexon3 as well as in Smad3, but not in Smad2(wt). In contrast, Smad2(wt), Smad2Deltaexon3, and Smad3 efficiently formed ARE-binding complexes with Smad4 and FAST1, although Smad2(wt) did not directly bind to ARE. These results suggest that exon 3 of Smad2 interferes with the direct DNA binding of Smad2, and modifies the function of Smad2 in transcription of certain target genes.

Alternative Splicing↗

PubMed1999

Trizygotic pregnancy consisting of two fetuses and a complete hydatidiform mole with dispermic androgenesis.

A triplet pregnancy in a 23-year-old woman was terminated at 15 weeks of gestation because of her severe hypertension, lung edema, and secondary hyperthyroidism. The pregnancy consisted of a hydatidiform mole with a 46,XY karyotype and two fetuses each with 46,XX and a 46,XY karyotype. To determine the zygosity and genetic origin of the mole and fetuses, PCR- and computer-assisted genotyping were performed at 27 CA-repeat marker loci that were distributed evenly over the genome. As a result, genotypes of the three pregnancy products were distinct from each other, indicating that the triplets were trizygotic. The mole lacked any maternal alleles but inherited both of the paternal alleles and/or one paternal allele in duplicate. This, along with the XY sex chromosome constitution, indicated that the mole resulted from dispermic androgenesis. The mother developed a persistent trophoblastic tumor thereafter.

Abortion, Therapeutic↗

PubMed1999

Carbonyl compounds cross-link cellular proteins and activate protein-tyrosine kinase p60c-Src.

Glyoxal, a dicarbonyl compound, is produced under oxidative stress by the autoxidation of glucose and reacts with the protein amino group to form Schiff base. In vitro treatment of murine thymocytes and fibroblasts with glyoxal induced extensive tyrosine phosphorylation of multiple proteins, which was drastically inhibited by the addition of OPB-9195, an inhibitor of the carbonyl reaction with proteins. Glyoxal induced cross-linking of a number of cellular proteins, including glycosylphosphatidylinositol (GPI)-anchored cell surface Thy-1. We then demonstrated that treatment of cells with glyoxal promptly induced activation of non-receptor protein-tyrosine kinase c-Src, which was partially inhibited by OPB-9195. It is suggested from these results that carbonyl amine reaction quickly activates c-Src, possibly through cross-linkage of GPI-anchored proteins or putative specific receptors.

Animals↗

PubMed1999

Crystallographic characterization of a novel protein SixA which exhibits phospho-histidine phosphatase activity in the multistep His-Asp phosphorelay.

SixA has been isolated from Escherichia coli as the first protein to exhibit phospho-histidine phosphatase activity. Recent biochemical studies have shown that SixA is involved in the signal transduction of the His-Asp phosphorelay through the dephosphorylation of the histidine-containing phosphotransfer (HPt) domain of the anaerobic sensor kinase ArcB. Crystals of SixA were obtained using a hanging-drop vapour-diffusion method with polyethylene glycol and calcium ions. Preliminary X-ray crystallographic analysis revealed that the crystals belonged to space group P212121 with unit-cell dimensions a = 39.26, b = 48.62 and c = 83.18 A, having one molecule in the crystallographic asymmetric unit. The intensity data were collected up to 1.5 A resolution using synchrotron radiation.

Aspartic Acid↗

PubMed1999

Clinical implications of coinfection with a novel DNA virus (TTV) in hepatitis C virus carriers on maintenance hemodialysis.

A novel hepatitis-associated DNA virus, designated as transfusion-transmitted virus (TTV), was identified recently. We investigated the frequency of TTV viremia in hepatitis C virus (HCV) carriers on maintenance hemodialysis to determine whether TTV coinfection has any clinical relevance. The subjects were 50 hemodialysis patients who had been followed over 4 years after diagnosis of HCV infection. Stored serum samples derived from each patient every 12th month after enrollment were subjected to polymerase chain reaction to amplify TTV DNA and HCV RNA. At enrollment, TTV viremia was detected in 24 (48%) HCV-positive patients irrespective of the number of previous blood transfusions and the duration of hemodialysis. The presence of TTV viremia had no relation to serum alanine aminotransferase (ALT) levels, HCV viremic levels or HCV genotypes. After enrollment, HCV infection persisted in all patients over the 4-year follow-up period, whereas spontaneous resolution of TTV infection was observed in 7 (29%) of the 24 TTV viremic cases (annual rate 7.3%, 95% confidence interval [CI] 0.8-25.5%). Evidence for TTV infection was found in 4 (15%) of the 26 TTV nonviremic patients (annual incidence 3.9%, 95% CI 0.1-19. 6%). The relationship between the ALT profile and TTV infection during follow up was not evident. Active TTV coinfection occurs frequently in HCV carriers undergoing hemodialysis but exerts no biochemical or virological influence on the underlying hepatitis C. Lack of disease association and the frequent spontaneous resolution of infection suggest that the clinical significance of TTV infection remains unclear.

Adult↗

PubMed1999

Promotional effects of CO2 laser on DMBA-induced hamster buccal pouch carcinogenesis as shown by immunohistochemistry of the placental form of glutathione S-transferase.

BACKGROUND AND OBJECTIVE: The purpose of the present study was to investigate the kinetics of the expression of the placental form of glutathione S-transferase (GST-P), a useful marker of premalignant lesions, and cell proliferation after CO2 laser surgery on the carcinogen-initiated epithelium. STUDY DESIGN/MATERIALS AND METHODS: CO2 laser incisions were made on buccal pouch epithelium of 36 hamsters after initiation by 9,10-dimethyl-1,2-benzanthracene (DMBA) (group 1, G1), and scalpel incisions were similarly made on 33 animals (group 2, G2). Twenty animals not treated further after initiation were used as DMBA-treated controls. Incidence of malignant transformation, expression of GST-P, and cell proliferation were examined. RESULTS: The incidence of malignant transformation in G1 and G2 increased significantly (G1: P < 0.001; G2: P < 0.05) compared with that in DMBA-treated controls. GST-P expression of hyperplasia in G1 and G2 decreased significantly (P < 0.001) compared with that in DMBA-treated controls. In hyperplasia, cell proliferation of the GST-P-negative area was significantly (P < 0.001) higher than that of the GST-P-positive area. CONCLUSION: The incisions, particularly by the CO2 laser, on the initiated areas made expression of GST-P decrease and cell proliferation increase in the GST-P-negative areas. These incisions may serve to promote malignant transformation.

9,10-Dimethyl-1,2-benzanthracene↗

PubMed1999

Licorice-induced hypokalemic myopathy and hypokalemic renal tubular damage in anorexia nervosa.

A patient with a history of anorexia nervosa developed licorice-induced hypokalemic myopathy. With potassium replacement, high CPK blood level and myopathic signs returned to normal. However, the patient manifested persistent hypokalemia and impaired renal function to concentrate and acidify the urine. Renal biopsy demonstrated intense degeneration and vacuolation of tubules with a normal glomerus which was consistent with hypokalemic nephropathy. Prolonged hypokalemia in anorexia nervosa is sometimes attributed to surreptitious purging or taking diuretics, but it is necessary to check the urine pH, the urine-specific gravity, and the urine potassium level in order to find underlying renal damage even after hypokalemic myopathy is treated successfully.

Adult↗

PubMed1999

Efficient selection of transgenic mouse embryos using EGFP as a marker gene.

We have established a reliable method that uses the EGFP (Enhanced Green Fluorescent Protein) gene as a marker for selecting transgenic embryos from preimplantation embryos. Embryos that were subjected to the pronuclear microinjection of the CMV/beta-actin/EGFP fusion gene were cultured in vitro until they developed into the morulae- or blastocyst-stage. The expression of EGFP was easily observed by a fluorescent microscopy. There appeared to be no damage to the in vivo developmental ability of the embryos in response to the EGFP excitation light, which utilized an IB filter for a period of 30 min. Modified PCR analysis using Dpn I and Bal 31 digestion of the embryonic DNA showed that all of the embryos expressing EGFP in all their cells were transgenic, while more than half with mosaic expression of EGFP were not transgenic. Approximately 77% of pups born from the embryos that uniformly expressed the EGFP gene were transgenic, while 21.4% of pups from the embryos with mosaic expression were transgenics. The results showed that the use of EGFP as a marker is very useful and reliable for selecting transgenic embryos, and that it is important to transfer the embryos expressing EGFP in all their cells to obtain truly transgenic animals.

Actins↗

PubMed1999

Determination of aspartic acid enantiomers in bio-samples by capillary electrophoresis.

Enantiomeric separation and detection of D,L-aspartic acid (Asp) derivatized with 4-fluoro-7-nitro-2,1,3-benzoxadiazole (NBD-F) by capillary electrophoresis (CE) using modified cyclodextrins as chiral selectors was studied. Heptakis(2,3, 6-tri-O-methyl)-beta-cyclodextrin(TM-beta-CD) was most effective for enantiomeric separation of NBD-D,L-Asp with optimum conditions of 30 mM TM-beta-CD in 50 mM phosphate buffer (pH 4.0) and the limit of detection (LOD) attained was 100 nM for each enantiomer. The method proposed in the present study was convenient for both D- and L-Asp determination since the other amino compounds migrated differently and D-Asp in bio-samples such as rat pineal gland and foods was determined with a simple sample pretreatment and a short analysis run time.

Animal Feed↗