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Biomedical subjects

T Kodama

Publications and source records attributed to T Kodama.

At least 217 records · Page 12Linked to original sources
PubMed1999

Increased insulin sensitivity and hypoglycaemia in mice lacking the p85 alpha subunit of phosphoinositide 3-kinase.

The hallmark of type 2 diabetes, the most common metabolic disorder, is a defect in insulin-stimulated glucose transport in peripheral tissues. Although a role for phosphoinositide-3-kinase (PI3K) activity in insulin-stimulated glucose transport and glucose transporter isoform 4 (Glut4) translocation has been suggested in vitro, its role in vivo and the molecular link between activation of PI3K and translocation has not yet been elucidated. To determine the role of PI3K in glucose homeostasis, we generated mice with a targeted disruption of the gene encoding the p85alpha regulatory subunit of PI3K (Pik3r1; refs 3-5). Pik3r1-/- mice showed increased insulin sensitivity and hypoglycaemia due to increased glucose transport in skeletal muscle and adipocytes. Insulin-stimulated PI3K activity associated with insulin receptor substrates (IRSs) was mediated via full-length p85 alpha in wild-type mice, but via the p50 alpha alternative splicing isoform of the same gene in Pik3r1-/- mice. This isoform switch was associated with an increase in insulin-induced generation of phosphatidylinositol(3,4,5)triphosphate (PtdIns(3,4,5)P3) in Pik3r1-/- adipocytes and facilitation of Glut4 translocation from the low-density microsome (LDM) fraction to the plasma membrane (PM). This mechanism seems to be responsible for the phenotype of Pik3r1-/- mice, namely increased glucose transport and hypoglycaemia. Our work provides the first direct evidence that PI3K and its regulatory subunit have a role in glucose homeostasis in vivo.

Animals↗
PubMed1999

De novo expression of the class-A macrophage scavenger receptor conferring resistance to apoptosis in differentiated human THP-1 monocytic cells.

The class-A macrophage scavenger receptor (MSR) is a trimeric multifunctional protein expressed selectively in differentiated monomyeloid phagocytes which mediates uptake of chemically modified lipoproteins and bacterial products. This study investigated whether MSR plays a role in the regulation of apoptosis, a model of genetically programmed cell death. De novo expression of MSR occurred in human THP-1 monocytic cells differentiated with phorbol esters, which activated a nuclear transcription factor binding to the Ap1/ets-like domain of the MSR promoter. The phorbol ester-stimulated THP-1 cells also expressed increased levels of the pro-apoptotic gene products, caspase-3 and Fas ligand, but the cells exhibited no change in apoptosis. Global activation of GTP-binding proteins with fluoride anions triggered apoptosis of THP-1 cells in a time- and concentration-dependent manner, demonstrated by nuclear shrinkage and fragmentation and internucleosomal DNA fragmentation. However, the MSR-expressing THP-1 macrophage-like cells showed a significant reduction in apoptosis compared to undifferentiated control THP-1 cells, which produce MSR at undetectable levels. Fluoride stimulation also triggered apoptosis of human Jurkat T cells. Stimulation with phorbol ester made no difference in apoptosis between treated and untreated Jurkat cells. Finally, Chinese hamster ovary (CHO) cells overexpressing the class-A MSR type I by cDNA transfection showed markedly increased resistance to G-protein-coupled apoptosis. Thus, de novo expression of MSR associated with monocyte maturation into macrophages appears to confer the resistance of macrophages to apoptotic stimulation by G-protein activation.

Animals↗
PubMed1999

STAT6 deficiency in a mouse model of allergen-induced airways inflammation abolishes eosinophilia but induces infiltration of CD8+ T cells.

BACKGROUND: The TH2-type cytokines have been reported to contribute to the asthmatic response. STAT6 has an essential role in IL-4 signalling and in production of TH2 cytokines from T cells and is involved in IgE and IgG1 responses after nematode infections, indicating that STAT6 has an important role in allergic diseases. OBJECTIVE: In this study we investigated the effects of STAT6 deficiency on allergen-induced airways inflammation in mice. METHODS: Both ovalbumin (OVA)-sensitized STAT6 deficient (STAT6-/-) mice and wild-type C57BL/6 mice were challenged with aerosolized OVA. Changes in inflammatory cell infiltration and cytokine levels in lung tissue as well as serum immunoglobulin levels were analysed in OVA-challenged STAT6-/- and wild-type mice. RESULTS: The eosinophilia and lung damage normally resulting from aeroallergen challenge were not seen in STAT6-/- mice. Expression of TH2 cytokines (IL-4 and IL-5) in the lung tissue as well as IgE and IgG1 responses after OVA challenge were profoundly reduced in STAT6-/- mice, whereas expression of IFNgamma was the same in STAT6-/- mice and wild-type mice after OVA challenge. Immunocytochemical analysis of T cells showed the infiltration of CD4+ T cells but not CD8+ T cells increased into the lung of wild-type mice after OVA challenge. However, the OVA-exposed STAT6-/- mice demonstrated the infiltration of both CD4+ T cells and CD8+ T cells with a significant increase in percentage and total number of CD8+ T cells compared with OVA-exposed wild-type mice. CONCLUSION: These results indicate that factors which signal through STAT6 are important regulators of eosinophilia of allergic airway inflammation, regulating TH2-type cytokine production both in CD4+ T cells and CD8+ T cells.

Allergens↗
PubMed1999

Oligonucleotide aggregates bind to the macrophage scavenger receptor.

We have prepared a model receptor containing a Lys cluster (320-340) in the collagen-like domain of the bovine macrophage scavenger receptor, and have shown that it has a similar binding specificity to the native scavenger receptor. The native scavenger receptor is reported to bind the quadruplex structure of nucleotides. In this study, we analyzed the model receptor binding of nucleotides with various structures, random, parallel or antiparallel quadruplex and aggregate forms. This was carried out by direct binding assays using labeled oligonucleotides or surface plasmon resonance, and by an inhibition assay using Chinese hamster ovary (CHO) cells expressing the scavenger receptor. The results showed that the nucleotides forming the quadruplex structure did not exhibit any binding. Only the aggregate forms of the nucleotide could bind to the model receptor. They also inhibited the degradation of acetylated low density lipoprotein by CHO cells expressing the native scavenger receptor, whereas nucleotides that did not bind to the model receptor had no effect on cellular acetylated low density lipoprotein degradation. Our results suggest that the quadruplex structure is not essential but may be required for the formation of the nucleotide aggregates, which can interact with the scavenger receptor.

Amino Acid Sequence↗
PubMed1999

Colony-stimulating factors in rapid eye movement sleep and non-rapid eye movement sleep regulation.

Although several cytokines are known to be somnogenic, no study has been conducted to examine whether colony-stimulating factors (CSF) affect sleep. Therefore, we studied the effects of granulocyte-macrophage CSF (GM-CSF) and macrophage CSF (M-CSF) on sleep in rats and their possible mechanism of action. At the dose of 10 pmol, GM-CSF or M-CSF significantly increased both non-rapid eye movement and rapid eye movement (REM) sleep or REM sleep only when infused intracerebroventricularly during the dark period. When injected locally in the hypothalamus, GM-CSF and M-CSF increased nitric oxide (NO) production. Thus, NOergic neural signals in the hypothalamus may take part in the somnogenic action of CSF.

Animals↗
PubMed1999

Acetylcholine and glutamate release during sleep-wakefulness in the pedunculopontine tegmental nucleus and norepinephrine changes regulated by nitric oxide.

Cholinergic neurons in the pons appear to play a major role in generating rapid eye movement (REM) sleep. In the present study, acetylcholine and glutamate release in the pedunculopontine tegmental nucleus (PPT) during the sleep-waking cycle were investigated by in vivo microdialysis. Acetylcholine release during slow wave sleep (SWS) was significantly lower (P<0.05) than during REM sleep and wakefulness. On the other hand, glutamate release during wakefulness was higher (P<0.05) than during REM sleep and SWS. Furthermore, the application of N-methyl-D-aspartate (1 mM) induced a significant increase of nitric oxides (NOx) for 20 min (P<0.05) and a decrease of norepinephrine for the first 15 min (P=0.01), indicating NOx regulation on norepinephrine release in PPT.

Acetylcholine↗
PubMed1999

Assessment of DNA content in formalin-fixed, paraffin-embedded tissue of lung cancer by laser scanning cytometer.

A new cytometric device, a laser scanning cytometer was developed to overcome the limitations of flow cytometry (FCM) and image analyses. The purpose of this study was to develop a method that allows laser scanning cytometry (LSC) to be used for measuring the cellular DNA content of paraffin-embedded tissues. Paraffin-embedded lung cancer tissue from 30 patients was analyzed by both FCM (p-FCM) and LSC (p-LSC). In addition, touch preparations from fresh frozen tissues were prepared to provide material for LSC (f-LSC). The limits of agreement for the DNA indices (DI) measured by p-LSC and p-FCM were -0.07 to 0.07, indicating that for a given case, these methods would be expected to differ by no more than 0.07. The limits of agreement for comparisons between the other materials and methods were wider and depended upon the size of the measurements. Agreement between f-LSC and p-FCM was good for small DI values, but poor for large values. Agreement between f-LSC and p-LSC was poor for small and large DI values, but good for moderately sized values. Discordancies in DNA ploidy status between different materials and methods may have been caused by either the heterogeneity within tumors, sampling errors or differences in the interpretation of histograms. This method allows a comparison of the results of DNA analysis with histologic findings from hematoxylineosin-stained sections and the prognosis of the patients.

Aneuploidy↗
PubMed1999

Relationship between the cagA 3' repeat region of Helicobacter pylori, gastric histology, and susceptibility to low pH.

BACKGROUND & AIMS: The variation in size of Helicobacter pylori CagA is related to repeat sequences in the 3' region of the cagA gene. We investigated whether structural subtypes of the cagA 3' region are associated with presentation of the infection or to susceptibility to acid. METHODS: We examined 319 cagA-positive H. pylori isolates: 84 isolates from Bogota, Colombia; 83 from Houston, Texas; 24 from Siena, Italy; and 128 from Seoul, Korea. The cagA 3' region was amplified by polymerase chain reaction. Gastric histology and susceptibility to pH 3 were evaluated in relation to the number of cagA repeat regions. RESULTS: Strains with more than three repeat regions were associated with significantly higher scores for gastric mucosal atrophy and intestinal metaplasia than those with fewer repeat regions. H. pylori strains with three repeat regions were also significantly more susceptible to pH 3 than isolates with fewer repeat regions. CONCLUSIONS: H. pylori strains with more than three repeat regions in the 3' region of the cagA gene are associated with enhanced histological injury and with reduced survival in acidic conditions. It is hypothesized that these variants arise within the stomach.

Adult↗
PubMed1999

A case of synchronous double primary lung cancer with neuroendocrine features.

We report a case of unique double primary lung cancers with neuroendocrine features in a 63-year-old male smoker. The mass in the left lower lobe (LLL) was a small cell/large cell carcinoma with spindle cell sarcomatous areas and organoid structure. The mass in the left upper lobe (LUL) was a tubular adenocarcinoma with neuroendocrine features including organoid nests showing occasional rosette formation, nuclear palisading in the periphery of the nests and positive immunoreaction for CD56, chromogranin A and synaptophysin. The difference in histological structures between the two masses led us to diagnose double primary lung cancer. The combination of small cell lung carcinoma and spindle cell carcinoma is very uncommon. The relationship between LLL and LUL tumors remains unclear. Multiple lung cancers with neuroendocrine features have only rarely been reported in the literature. The patient in our case died of widespread cancer 2 years and 4 months after the surgery without adjuvant chemotherapy, a longer postoperative survival time than in cases of ordinary extensive small cell lung cancer. Multiple lung cancers with neuroendocrine features are extremely rare and similar cases have not been reported in the literature. Neuroendocrine differentiation has attracted widespread attention and, therefore, examining neuroendocrine features in lung cancers is important.

Adenocarcinoma↗
PubMed1999

Structure and enzymatic properties of genetically truncated forms of the water-insoluble glucan-synthesizing glucosyltransferase from Streptococcus sobrinus.

Glucosyltransferase-I (GTF-I: 175 kDa) of a cariogenic bacterium, Streptococcus sobrinus 6715, mediates the conversion of water-soluble dextran (alpha-1,6-glucan) into a water-insoluble form by making numerous alpha-1,3-glucan branches along the dextran chains with sucrose as the glucosyl donor. The structures and catalytic properties were compared for two GTF-I fragments, GTF-I' (138 kDa) and GS (110 kDa). Both lack the N-terminal 84 residues of GTF-I. While GTF-I' still contains four of the six C-terminal repeats characteristic of streptococcal glucosyltransferases, GS lacks all of them. Electron microscopy of negatively stained samples indicated a double-domain structure for GTF-I', consisting of a spherical head with a smaller spherical tail, which was occasionally seen as a long extension. GS was seen just as the head portion of GTF-I'. In the absence of dextran, both fragments simply hydrolyzed sucrose with similar K(m) and k(cat) values at low concentrations (<5 mM). At higher sucrose concentrations (>10 mM), however, GTF-I' exhibited glucosyl transfer activity to form insoluble alpha-1, 3-glucans. So did GS, but less efficiently. Dextran increased the rate and efficiency of the glucosyl transfer by GTF-I'. On removal of the C-terminal repeats of GTF-I' by mild trypsin treatment, this dextran-stimulated transfer was completely lost and the dextran-independent transfer became less efficient. These results indicate that the N-terminal two-thirds of the GTF-I sequence are organized as a structurally and functionally independent domain to catalyze not only sucrose hydrolysis but also glucosyl transfer to form alpha-1,3-glucan chains, although not efficiently; the C-terminal repeat increases the efficiency of the intrinsic glucosyl transfer by the N-terminal domain as well as rendering the whole molecule primer-dependent for far more efficient insoluble glucan synthesis.

Bacterial Proteins↗
PubMed1999

Accompanying arteries of the lesser saphenous vein and sural nerve: anatomic study and its clinical applications.

The arteries adjacent to the lesser saphenous vein and sural nerve were investigated in 10 fresh cadavers that had been systemically injected with a lead oxide-gelatin mixture. The accompanying arteries were found to lie along the lesser saphenous vein and sural nerve and to nourish the skin through venocutaneous and neurocutaneous perforators. On the basis of the anatomy of these accompanying arteries, the lesser saphenous venoadipofascial (VAF) pedicled fasciocutaneous flap and the lesser saphenous-sural veno-neuro adipofascial (V-NAF) pedicled fasciocutaneous flap have been developed and applied to 23 cases of various reconstructions of the lower extremity with proximal and distal bases. Survival of the flaps has been extremely good, and the flaps have been clinically useful.

Adult↗
PubMed1999

Hydrogenophilus thermoluteolus gen. nov., sp. nov., a thermophilic, facultatively chemolithoautotrophic, hydrogen-oxidizing bacterium.

The taxonomic positions of 'Pseudomonas hydrogenothermophila' strain TH-1 and 'Flavobacterium autothermophilum' strain TH-4 were studied by 16S rDNA sequencing. These organisms are Gram-negative, strictly aerobic, thermophilic, facultatively chemolithoautotrophic hydrogen-oxidizing rods and have a DNA G + C content of 63-65 mol%. The major isoprenoid quinone is ubiquinone-8 and 3-hydroxy decanoic acid (3-OH C10:0) is the major 3-hydroxy cellular fatty acid. A phylogenetic analysis based on 16S rDNA sequences placed strains TH-1T and TH-4 in the beta-subclass of the Proteobacteria. The taxonomic characteristics of these organisms are different from those of previously described aerobic, facultatively chemolithoautotrophic, hydrogen-oxidizing bacteria that belong to the beta-subclass of Proteobacteria. On the basis of the information described above, a new genus and species, Hydrogenophilus thermoluteolus gen. nov., sp. nov., is described to include both strains. The type strain is strain TH-1T (= IFO 14978T).

Base Composition↗
PubMed1999

Development of an enzyme-labeled oligonucleotide probe for detecting the Escherichia coli attaching and effacing A gene.

Enteropathogenic Escherichia coli (EPEC) and enterohemorrhagic Escherichia coli (EHEC) can produce attaching and effacing (AE) lesions on intestinal epithelium in vitro and in vivo. A gene necessary to cause the AE lesion has been identified and designated Escherichia coli attaching and effacing A (eaeA) gene. In this study, an alkaline phosphatase (ALP)-conjugated oligonucleotide probe for the eaeA gene was developed and used to detect the eaeA gene among 163 strains of classical EPEC and 25 strains of EHEC O157. The prevalence rates of eaeA gene in the strains of classical EPEC and EHEC O157 were 51.5 and 100%, respectively. The eaeA-positive rate (60.0%) in strains of class I EPEC serogroups (O26, O55, O86, O111, O119, O125, O126, O127, O128ab, and O142) was significantly higher than that (22.9%) in strains of the class II EPEC serogroups (O18, O44, O114) (P<0.01). A total of 109 eaeA-positive classical EPEC and EHEC O157 were positive for fluorescent actin staining (FAS) assay, whereas 79 eaeA-negative classical EPEC were negative. Both the sensitivity and specificity of the eaeA probe versus the FAS assay positivity were 100%. Thus, use of the ALP-conjugated oligonucleotide probe for the eaeA gene would be specific and reliable in identifying the adherence capability of EPEC and EHEC.

Adhesins, Bacterial↗
PubMed1999

Clonal analysis of adenosquamous carcinoma of the lung.

Adenosquamous carcinoma of the lung is a subset of pulmonary carcinomas, and comprises less than 4% of lung carcinomas. Its histogenesis remains unclear. The clonality of adenosquamous carcinoma from four female patients was analyzed to determine whether the clonality between the squamous cell and adenocarcinomatous components coincides. Each lesion was precisely microdissected from methanol-fixed sections. Adjacent normal lung tissue was collected as a normal control. DNA was extracted for clonal analysis based on an X-chromosome-linked polymorphic marker, the human androgen receptor gene (HUMARA). HUMARA was found to be amplified with or without previous digestion by the methylation-sensitive restriction endonuclease HpaII. All four cases were informative. Squamous cell and adenocarcinomatous components showed identical monoclonal patterns in all four patients. In one case, only the squamous cell carcinomatous component showed loss of heterozygosity of the HUMARA locus. The results suggest that the squamous cell and adenocarcinomatous components originate from the same cell.

Aged↗
PubMed1999

Association between smoking and tumor progression in Japanese women with adenocarcinoma of the lung.

We studied the effect of smoking on tumor progression in 3312 patients with lung cancer registered at the National Matsudo Hospital and National Cancer Center Hospital East between 1977 and 1996. The odds ratios of the following variables for tumor extent (localized versus advanced disease) and hazard ratios for survival were calculated in both sexes separately using the logistic regression and Cox proportional hazard models, respectively: smoking history, number of cigarettes smoked per day, pack-years smoked, age, histological type, and the year of admission. Of the 943 women, 367 (38.9%) were smokers and 694 (73.6%) had adenocarcinoma, whereas of the 2369 men, 2255 (95.2%) were smokers and 1010 (42.6%) had adenocarcinoma. In female adenocarcinoma patients, the odds ratio (95% confidence interval) for advanced disease and the hazard ratio (95% confidence interval) for survival with an increase of 30 cigarettes smoked per day were 2.86 (1.49-5.49) and 1.52 (1.13-2.04), respectively, but in those with non-adenocarcinoma, the odds ratio and hazard ratio were 0.96 (0.41-2.23) and 1.13 (0.75-1.70), respectively. In male patients, smoking history influenced tumor progression regardless of histological type, but the odds ratios and hazard ratios were lower than those for women with adenocarcinoma. In conclusion, smoking habit was closely correlated with progression of adenocarcinoma in women. This association was not observed in women with non-adenocarcinoma and was weaker in men, suggesting various effects of smoking on lung cancer development depending on gender and the histological type of the tumor.

Adenocarcinoma↗
PubMed1999

Role of gamma interferon in Helicobacter pylori-induced gastric inflammatory responses in a mouse model.

The immune responses to Helicobacter pylori infection play important roles in gastroduodenal diseases. The contribution of gamma interferon (IFN-gamma) to the immune responses, especially to the induction of gastric inflammation and to protection from H. pylori infection, was investigated with IFN-gamma gene knockout (IFN-gamma-/-) mice. We first examined the colonizing abilities of eight H. pylori strains with a short-term infection test in order to select H. pylori strains which could colonize the mouse stomach. Only three strains (ATCC 43504, CPY2052, and HPK127) colonized C57BL/6 wild-type mice, although all of the strains except for ATCC 51110 could colonize IFN-gamma-/- mice. The number of H. pylori organisms colonizing the stomach in wild-type mice was lower than that in IFN-gamma-/- mice. Oral immunization with the CPY2052 sonicate and cholera toxin protected against infection with strain CPY2052 in both types of mouse. These findings suggested that IFN-gamma may play a protective role in H. pylori infection, although the degree of its protective ability was estimated to be low. In contrast, in a long-term infection test done to examine the contribution of IFN-gamma to gastric inflammation, CPY2052-infected wild-type mice developed a severe infiltration of mononuclear cells in the lamina propria and erosions in the gastric epithelium 15 months after infection, whereas CPY2052-infected IFN-gamma-/- mice showed no inflammatory symptoms. This result clearly demonstrated that IFN-gamma plays an important role in the induction of gastric inflammation caused by H. pylori infection.

Adjuvants, Immunologic↗
PubMed1999

The Bacillus subtilis yaaH gene is transcribed by SigE RNA polymerase during sporulation, and its product is involved in germination of spores.

The expression of 21 novel genes located in the region from dnaA to abrB of the Bacillus subtilis chromosome was analyzed. One of the genes, yaaH, had a predicted promoter sequence conserved among SigE-dependent genes. Northern blot analysis revealed that yaaH mRNA was first detected from 2 h after the cessation of logarithmic growth (T(2)) of sporulation in wild-type cells and in spoIIIG (SigG(-)) and spoIVCB (SigK(-)) mutants but not in spoIIAC (SigF(-)) and spoIIGAB (SigE(-)) mutants. The transcription start point was determined by primer extension analysis; the -10 and -35 regions are very similar to the consensus sequences recognized by SigE-containing RNA polymerase. A YaaH-His tag fusion encoded by a plasmid with a predicted promoter for the yaaH gene was produced from T(2) of sporulation in a B. subtilis transformant and extracted from mature spores, indicating that the yaaH gene product is a spore protein. Inactivation of the yaaH gene by insertion of an erythromycin resistance gene did not affect vegetative growth or spore resistance to heat, chloroform, and lysozyme. The germination of yaaH mutant spores in a mixture of L-asparagine, D-glucose, D-fructose, and potassium chloride was almost the same as that of wild-type spores, but the mutant spores were defective in L-alanine-stimulated germination. These results suggest that yaaH is a novel gene encoding a spore protein produced in the mother cell compartment from T(2) of sporulation and that it is required for the L-alanine-stimulated germination pathway.

Amino Acid Sequence↗