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Biomedical subjects

Y Omori

Publications and source records attributed to Y Omori.

At least 19 recordsLinked to original sources
PubMed2006

Assessment of microsatellite instability status for the prediction of metachronous recurrence after initial endoscopic submucosal dissection for early gastric cancer.

The technique of endoscopic submucosal dissection (ESD) has been developed for en bloc resection of early gastric cancer (EGC); however, little is known about the risk of metachronous cancer in the remnant stomach after initial ESD. In this study, we investigated the correlation between microsatellite instability (MSI) status and the incidence of metachronous recurrence of gastric cancer. According to the genetic/molecular background determined with MSI status and expression levels of hMLH1 and p53 tumour suppressor, 110 EGCs removed with ESD were subclassified into three groups: the mutator/MSI-type (8%), suppressor/p53-type (45%) and unclassified type (47%). Interestingly, patients with the mutator/MSI-type tumour had a high incidence (67%) of metachronous recurrence of gastric cancer within a 3-year observation after initial ESD, which was significantly higher than those with the suppressor/p53-type and unclassified type tumours (P<0.01). Although we investigated mucin phenotypes, there was no correlation between mucin phenotype and the recurrence of EGC. These findings suggest that subclassification of molecular pathological pathways in EGCs is required for the assessment of patients with a high risk of recurrent gastric cancer. The information delivered from our investigation is expected to be of value for decisions about therapy and surveillance after ESD.

Aged↗
PubMed2004

An autopsy case of bacterial septic shock 12 years following ABO-incompatible renal transplantation.

We report the case of an ABO-incompatible kidney transplant recipient who died suddenly following a good transplant course of 12 years. For 10 years after transplantation, the graft function had been stable (s-Cr: 1.0-1.5 mg/dL), although chronic hepatitis C had developed, with elevation of transaminase. In the 11th year, he was admitted into the hospital with low-grade fever and general fatigue. Jaundice and anaemia progressed, and he died 2 months after admission. The autopsy diagnosis was: (1) post-renal transplantation state, (2) phlegmonous enterocolitis with septic infarction, (3) cellulitis and necrotic myositis, and (4) sepsis. The transplanted kidney graft showed well-preserved glomeruli and tubules, corresponding to chronic allograft nephropathy (CAN) grade Iota (ci1, ct1, cv1), according to the Banff classification. The pathological changes observed in this long-surviving ABO-incompatible kidney graft were similar to those of an ABO-compatible graft, although its degree was milder.

ABO Blood-Group System↗
PubMed2001

Control of intracellular movement of connexins by E-cadherin in murine skin papilloma cells.

The gap junctional intercellular communication-deficient mouse skin papilloma cell line P3/22 expresses Cx43 but not E-cadherin. The E-cadherin gene-transfected cells (P3E1) communicate in a calcium-dependent manner and they were used to study how E-cadherin restores the function of connexins. At low calcium, Cx43 molecules remain in the cytoplasm of P3E1 cells and appear at cell-cell contact areas only in high-calcium medium. While Cx43 is unphosphorylated in P3E1 cells in low-calcium medium, two phosphorylated bands appeared at high calcium. However, when Cx26, which has no C-terminal tail that can undergo phosphorylation, was expressed in P3E1 cells, this connexin also moved to the plasma membrane after the calcium shift and partly colocalized with Cx43, suggesting that C-terminal phosphorylation is not essential for E-cadherin-mediated intracellular transport of connexins. In low calcium, both Cx26 and Cx43 remained and colocalized in the endoplasmic reticulum. As early as 30 min after the shift to high-calcium medium, both Cx43 and Cx26 began to accumulate in the Golgi apparatus. Intracellular movement of connexins to the cytoplasmic membrane at high calcium was effectively blocked by cytochalasin D and brefeldin A. These results suggest that E-cadherin junction formation at high calcium leads to formation of actin cables, which directly or indirectly transport connexins from the cytoplasm to the cell-cell contact membranes via the Golgi apparatus.

Actins↗
PubMed2001

Involvement of gap junctions in tumor suppression: analysis of genetically-manipulated mice.

Accumulating evidence indicates that gap junctions play an important role in the maintenance of normal cell growth, so that genes for the connexin gap junction proteins form a family of tumor-suppressor genes. Although mice from which nine types of connexin gene are deleted have been established, little information from carcinogenesis experiments with these mice is available. We have previously found several mutant forms of connexin 32 (Cx32) to be able to inhibit, in a dominant-negative manner, gap junctional intercellular communication (GJIC) exerted by wild-type Cx32. By introducing a gene for such a dominant-negative Cx32 mutant expressed under the control of a liver-specific albumin gene promoter, we have generated transgenic mouse lines in which the function of Cx32 is down-regulated only in the liver. Although GJIC was diminished in the transgenic liver as expected, the reduced GJIC did not affect viability nor the number of spontaneous liver tumors. Although susceptibility to diethylnitrosamine-induced hepatocarcinogenesis was significantly elevated in the transgenic mice, liver regeneration after partial hepatectomy was delayed compared with wild-type mice, suggesting that gap junctions function not only to suppress excessive cell growth but also to promote cell proliferation when necessary for normal function of tissues. Although the phenotype of Cx32-deficient mice was similar to that of the transgenic mice, the former showed more drastically altered phenotypes, i.e. increased BrdU incorporation in the quiescent liver and development of spontaneous liver tumors. We also established 3T3 fibroblasts from embryos lacking the Cx43 gene and characterized their growth. These fibroblasts showed no difference from the wild type in growth characteristics. From these and other studies, we suggest that gap junctions do not necessarily suppress cell growth but support an optimal growth rate.

Animals↗
PubMed2001

CREB-H: a novel mammalian transcription factor belonging to the CREB/ATF family and functioning via the box-B element with a liver-specific expression.

The expression of liver-specific genes is regulated by unequivocally allocated transcription factors via proper responsible elements within their promoters. We identified a novel transcription factor, CREB-H, and found that its expression was restricted in the liver among 16 human tissues tested. A region of CREB-H exhibited significant homology to the basic leucine zipper (b-Zip) domain of members of the CREB/ATF family: mammalian LZIP and Drosophila BBF-2 that binds to box-B, a Drosophila enhancer modulating the fat-body-specific gene expression. CREB-H contained a hydrophobic region representing a putative transmembrane domain, like LZIP. Constructing a variety of CREB-H fusion proteins with the GAL4 DNA-binding domain disclosed that CREB-H functioned as a transcriptional activator and its N-terminal 149 amino acids accounted for the activation ability. Gel mobility sift assays revealed that CREB-H did not bind to the C/EBP, AP-1 and NF-kappaB elements but specifically bound to CRE and the box-B element. Luciferase reporter assays demonstrated that like BBF-2, CREB-H activated transcription via the box-B element and that a deletion of the putative transmembrane domain increased the activation of reporter expression significantly. Furthermore, a fusion protein of GFP and full-length CREB-H was localized in reticular structures surrounding the nucleus, whereas a fusion protein of GFP and a deletion mutant lacking the putative transmembrane domain was mainly in the nucleus. These findings suggest that CREB-H plays an important role in transcriptional regulation of genes specifically expressed in the liver, and that the putative transmembrane domain may be associated with modulation of its function as the transcriptional activator.

Activating Transcription Factors↗
PubMed2001

A questionnaire for neurological symptoms in patients with diabetes--cross-sectional multicenter study in Saitama Prefecture, Japan.

This study was designed to investigate the prevalence of neurological symptoms in diabetic patients living in Saitama Prefecture, Japan using 13-item questionnaire. A total of 6472 outpatients with diabetes (3417 men and 3055 women) were recruited from 100 centers. Mean age and mean disease duration were 60.9-year old and 10.4 years, respectively. The questionnaire for monitoring of neurological symptoms was completed at the clinic or hospital visited, and Achilles' tendon reflex, ophthalmologic, blood and urinary examinations were also performed. Of the 6472 patients, 84.8% suffered from a mean of 3.3+/-2.2 neurological symptoms. However, half of these symptoms were not considered to be those of diabetic neuropathy by attending physicians. "Feeling as if a piece of paper is attached to the sole of the foot," "stinging and prickling sensations in feet," and "pain in feet" were the most common symptoms of diabetic neuropathy. The prevalence of diabetic neuropathy as determined by attending physician increased with disease duration and worse control of diabetes. This study found that the majority of diabetics were suffered from neurological symptoms, although half of such symptoms were not considered to be those of diabetic neuropathy by physicians. Furthermore, it is important for diabetics to be diagnosed and treated earlier to prevent progression to severe neuropathic complications by means of optimal glycemic control and use of some chemicals such as aldose reductase inhibitor, and to develop this study to evaluate the efficacy of treatments.

Aged↗
PubMed2001

Reduction of malignant phenotype of HEPG2 cell is associated with the expression of connexin 26 but not connexin 32.

Connexin (Cx) genes have a negative growth effect on tumour cells with certain specificity. However, it is not clear whether each Cx gene can act similarly in growth control. Hepatocytes normally express Cx26 and Cx32 as their major gap junction genes, but HepG2 cells, a hepatoma cell line, are deficient in gap junctional intercellular communication (GJIC) based on the down-regulation of Cx26 and aberrant localization of Cx32. In this study, we showed that some of the expressed Cx26 protein in HepG2 cells localized in the plasma membrane and contributed to recovery of GJIC, while the Cx32 protein remained localized in the cytoplasm. The Cx26-transfected clones showed a significantly slower growth in vivo as well as in vitro and reduced anchorage-independent growth ability compared with a mock-transfected clone. Cx26-transfected cells had more regular cell layers due to the re-establishment of the E-cadherin cell adhesion complex. E-cadherin expression following Cx26 transfection was induced. Cx26 expression simultaneously brought E-cadherin and beta-catenin proteins into the plasma membrane without any change in the expression level of beta-catenin protein. These results suggest that the expression of Cx26 contributes to negative growth control of HepG2 cells and the morphological change through the induction of E-cadherin and subsequent formation of cell adhesion complex.

Animals↗
PubMed2000

Connexin43 suppresses MFG-E8 while inducing contact growth inhibition of glioma cells.

Gap junction expression has been reported to control the growth of a variety of transformed cells. We undertook parallel analysis of connexins Cx32 and Cx43 in glioma cells, which revealed potential mechanisms underlying this phenomenon and led to several novel findings. Cx43, but not Cx32, suppressed C6 glioma cell growth. Paradoxically, Cx32 transfection resulted in severalfold more dye transfer than Cx43. However, Cx43 transfectants shared endogenous metabolites more efficiently than Cx32 transfectants. Interestingly, a significant portion of Cx43 permeants were incorporated into macromolecules more readily than those that transferred via Cx32. Cx43 induced contact inhibition of cell growth but in contrast to other reports, did not affect log phase growth rates. Cell death, senescence, or suppression of growth factor signaling was not involved because no significant alterations were seen in cell viability, telomerase, or mitogen-activated protein kinase activity. However, suppression of cell growth by Cx43 entailed the secretion of growth-regulatory factors. Most notably, a major component of conditioned medium that was affected by Cx43 was found to be MFG-E8 (milk fat globule epidermal growth factor 8), which is involved in cell anchorage and integrin signaling. These results indicate that Cx43 regulates cell growth by the modulation of extracellular growth factors including MFG-E8. Furthermore, the ability of a Cx to regulate cell growth may rely on its ability to mediate the intercellular transfer of endogenous metabolites but not artificial dyes.

Amino Acid Sequence↗
PubMed2000

Comparative PCR: a simple and sensitive method for quantifying low-abundance mRNA species.

To measure low-abundance messenger RNA species comparatively, we developed a simple and highly sensitive quantification method designated comparative PCR. Messenger RNAs from two samples were converted into cDNAs with modified oligo(dT) primers (designated RT primers) containing a sample-specific sequence and a common sequence. After equal amounts of the cDNAs were mixed together, a target gene was amplified by competitive PCR with additional primers: a gene-specific primer and a primer consisting of the common sequence of the RT primers. The amplified products were visualized by the final PCR, designated fluorescence PCR, with an additional three primers: two different fluorescence-labeled primers consisting of the sample-specific sequence within the RT primers and a nested gene-specific primer. Expression levels of the target gene in the two samples were measured by calculating ratios of two different fluorescence intensities. We could quantify 0.1-0.3 copies of the target mRNA per cell from only 0.5 ng of poly(A)(+) RNA for a single detection. This system should be useful for sensitive measurement of scarce transcripts from small samples with a limited amount of RNA such as biopsy specimens.

Animals↗
PubMed2000

Worldwide differences in the incidence of insulin autoimmune syndrome (Hirata disease) with respect to the evolution of HLA-DR4 alleles.

The relationship between the geographic distribution of susceptibility genes to insulin autoimmune syndrome (IAS) and the incidence of insulin autoimmune syndrome was investigated in order to examine the distribution of the genetic background to susceptibility to certain diseases. The HLA-DR4 allele, DRB1*0406, is associated with increased susceptibility to IAS among Japanese, while the DRB1*0403 and DRB1*0407 alleles are not (the odds ratio of which are 1.6 and 1.1, respectively). The worldwide geographic distribution of the three DR*04 alleles showed that the distribution of DRB1*0403 encompassed that of DRB1*0406 and DRB1*0407. Taken together with the findings that Glu at position 74 in the DRB1 molecule is shared by the three DRB1*04 alleles, there are only a few differences between the DRB1 molecule-nucleotide sequences of DRB1*0403, DRB1*0406 and DRB1*0407, and that all the three DRB1*04 alleles are carried by the same class II haplotype, DQA1*0301/DQB1*0302, it may be considered that DRB1*0403 is the ancestral allele of DRB1*0406 and DRB1*0407. Therefore, populations with a higher prevalence of DRB1*0406 have a higher risk of developing IAS. The extremely low prevalence of IAS among Caucasians can be explained by the low prevalence of DRB1*0406 in this population. This is a good example of the association between the predisposition to risk of development of certain diseases and the evolution of susceptibility genes.

Alleles↗
PubMed2000

Induction of skin papillomas, carcinomas, and sarcomas in mice in which the connexin 43 gene is heterologously deleted.

It has been suggested that blocked gap junctional intercellular communication plays a crucial part in multistage carcinogenesis. The mouse skin tumor-promoting phorbol esters are potent inhibitors of gap junctional intercellular communication and this inhibition is considered to be a mechanism by which clonal expansion of "initiated" cells is promoted. We examined whether mice in which the gene for a gap junction protein, connexin 43, is heterozygously deleted are more susceptible to chemical carcinogenesis; connexin 43 is expressed in the basal cell layer and the dermis of the skin. When the back skin was painted with 7,12-dimethylbenz[a]anthracene and 12-O-tetradecanoylphorbol 13-acetate, the incidence and yields of both papillomas and carcinomas were similar in connexin 43+/- and connexin 43+/+ mice; for this experiment, the original mice with C57BL/6 genetic background was crossed with CD1 strain for three generations. Subcutaneous injection of 7, 12-dimethylbenz[a]anthracene resulted in induction of fibrosarcomas in connexin 43+/- and connexin 43+/+ mice to a similar extent. All papillomas and carcinomas induced with 7, 12-dimethylbenz[a]anthracene and 12-O-tetradecanoylphorbol 13-acetate contained the 7,12-dimethylbenz[a] anthracene-specific mutation in the ras gene (A to T transversion at the 61st codon). About 50% of fibrosarcomas also contained this mutation, but in the Ki-ras gene; there was no difference in the prevalence of this mutation in tumors from connexin 43+/- and connexin 43+/+ mice. None of the tumors examined, however, showed any mutation in the connexin 43 gene. These results suggest that the deletion of one allele of the connexin 43 gene does not significantly contribute to, nor alter, the molecular events involved in skin carcinogenesis. These results are compatible with previous observations that nongenetic disruption of function rather than mutations of connexins, commonly occurs in cancer cells.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed2000

Treatment with alpha-glucosidase inhibitor for severe reactive hypoglycemia: a case report.

Gastrectomy or vagotomy may result in reactive hypoglycemia, which, in some cases, can reduce the plasma glucose levels to 30-40 mg/dl due to rapid digestion and absorption of food, especially carbohydrates. It also occurs sometimes in patients on hemodialysis, where it is a potentially lethal complication. Because insulin has a longer half-life due to lack of renal degradation, hypoglycemia can be induced by insulin in patients with renal failure. We treated a patient with frequent episodes of severe hypoglycemia, that were sometimes accompanied by convulsions. He had undergone total gastrectomy 8 years before and had been maintained on hemodialysis for 3 years. Hyperinsulinemia caused by oxyhyperglycemia associated with post-gastrectomy led to severe hypoglycemia in this patient because of the lack of renal insulin degradation. Since nutritional treatment did not successfully manage his reactive hypoglycemia, an alpha-glucosidase inhibitor, acarbose, was administered to treat his oxyhyperglycemia. This therapy was very effective and he has not had any recurrence of reactive hypoglycemia since the initiation of the therapy.

Enzyme Inhibitors↗
PubMed2000

Association of postprandial hypertriglyceridemia and carotid intima-media thickness in patients with type 2 diabetes.

OBJECTIVE: Serum triglyceride levels are important in the development of atherosclerosis. Although triglyceride levels are generally increased in the postprandial periods, the association between postprandial triglyceride (pTG) levels and atherosclerosis has not been investigated in diabetic patients. To investigate the role of pTG levels in atherosclerosis, we examined the correlation between pTG levels and carotid intimal-medial thickness (IMT). RESEARCH DESIGN AND METHODS: Carotid IMT was measured by ultrasonography in 61 patients with type 2 diabetes. Plasma glucose (PG), insulin, total cholesterol, triglycerides, and HDL cholesterol levels were measured after overnight fasting and 4 h after a meal. RESULTS: Carotid IMT of the patients with fasting hypertriglyceridemia was greater than that of the patients with normal fasting triglyceride (fTG) levels (0.85+/-0.12 vs. 0.76+/-0.14 mm; P = 0.02). The carotid IMT was increased in the patients with pTG levels >2.27 mmol/l. The normo-normo (NN) and normo-hyper (NH) groups consisted of patients with normal fTG levels but with pTG levels <2.27 and >2.27 mmol/l, respectively. Patients with both hypertriglyceridemia and pTG levels >2.27 mmol/l formed the hyper-hyper (HH) group. Carotid IMT was significantly increased in the NH (0.86+/-0.13 mm) and HH (0.85+/-0.12 mm) groups compared with the NN group (0.73+/-0.13 mm; P<0.01). Although postprandial PG, pTG, and fasting LDL cholesterol levels were all independently correlated with carotid IMT, pTG levels had the strongest statistical influence (P = 0.002). CONCLUSIONS: Postprandial hypertriglyceridemia despite normal fTG levels may be an independent risk factor for early atherosclerosis in type 2 diabetes.

Adult↗
PubMed1999

Optical resolution and absolute configuration of N-benzyloxycarbonyl-alpha-alkoxyglycines

Optical resolution of racemic N-benzyloxycarbonyl-protected alpha-alkoxyglycines, (+/-)-Cbz-Gly(OR)-OH (R = Et and Pr(i)), was achieved by means of fractional crystallization of diastereomeric salts with (+)-(1S,2S)-2-amino-1-phenyl-1,3-propanediol or diastereomeric esters of (+)- or (-)-menthol. The D- and L-configurations were assigned to the (+)- and (-)-Cbz-Gly(OR)-OH, respectively, based on L-enantioselective enzymatic hydrolysis of (+/-)-Cbz-Gly(OR)-OR' (R = Me, Et, and Pr(i); R' = CH(2)CF(3) and Me) using porcine pancreatic lipase and papain. Chiroptical properties and HPLC retention times of D- and L-Gly(OR)-residue (R = Me and Pr(i))-containing peptides were compared in relation to their configurational assignments. Copyright 1999 Wiley-Liss, Inc.

Journal Article↗