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Biomedical subjects

M Namba

Publications and source records attributed to M Namba.

At least 37 records · Page 2Linked to original sources
PubMed2001

Protection of mice from LPS-induced shock by CD14 antisense oligonucleotide.

CD14 is a pattern recognition receptor on myeloid cells and plays a pivotal role in an innate immune system that is responsible for Gram-negative and Gram-positive bacteria infection. Lipopolysaccharide (LPS), a cell wall component of Gram-negative bacteria, can induce production of a large quantity of proinflammatory cytokines into the circulation mediated by CD14-mediated macrophages and monocytes. These cytokines eventually cause septic shock. Several in vitro and in vivo studies have shown that suppression of a CD14 function by a CD14 antibody led to an inhibition of the production of proinflammatory cytokines such as TNF-alpha, IL-1 beta, and IL-8. In the present study, we found that CD14 antisense oligonucleotide (ODN) can prevent lethal LPS shock in D-galactosamine-sensitized mice. This ODN inhibited CD14 expression in a mouse macrophage cell line, RAW264.7, and suppressed production of TNF-alpha in LPS-stimulated RAW264.7 cells. Furthermore, we designed a consensus antisense ODN that could hybridize human and mouse CD14 RNA, and we evaluated its efficacy. The consensus antisense ODN rescued mice primed with Mycobacterium bovis bacillus Calmette-Guerin (BCG) from the LPS-induced lethal shock. In this model, the CD14 antisense ODN down-regulated LPS-elicited CD14 expression in the liver, resulting in a decrease in LPS-induced TNF-alpha production. These findings suggest that the CD14 antisense ODN is distributed in the liver and efficiently suppresses LPS-induced TNF-alpha production by reducing CD14 expression on Kupffer cells. This CD14 antisense ODN may be useful for the development of a therapeutic agent against sepsis and septic shock.

Animals↗
PubMed2001

Pancreatic biopsy as a procedure for detecting in situ autoimmune phenomena in type 1 diabetes: close correlation between serological markers and histological evidence of cellular autoimmunity.

To better understand the pathogenesis of type 1 diabetes, we have developed pancreatic biopsy under laparoscope for recent-onset type 1 diabetic patients. The patients included 29 acute-onset type 1 diabetic patients, 5 latent-onset type 1 diabetic patients, and 1 type 2 diabetic patient. Their median age was 28 years, and the duration of diabetes at the time of biopsy was approximately 3 months. In 31 of 35 patients, we could obtain the pancreas tissue by punching. No serious complications, such as heavy bleeding, peritonitis, or pancreatitis, have been experienced. Pneumoderma was observed in two patients, and abdominal dull pain had continued for 2 days in two patients. However, special treatment was not necessary for these complications. T-cell-predominant infiltration to islets (insulitis) and hyperexpression of major histocompatibility complex class I antigens on islet cells were the two major findings and were observed in 17 of 29 recent-onset type 1 diabetic patients. These findings could be regarded as evidence of immune attack against beta-cells, and their presence was closely correlated with the presence of either anti-GAD or anti-IA-2 antibodies (P = 0.02). In conclusion, pancreatic biopsy under laparoscope is a safe procedure without serious complications, according to our findings, for detecting in situ autoimmune phenomenon in recent-onset type 1 diabetic patients.

Adolescent↗
PubMed2001

Helicobacter pylori induces pepsinogen secretion by rat gastric cells in culture via a cAMP signal pathway.

Infection with Helicobater pylori (H. pylori) is associated with various stomach diseases such as chronic gastritis, peptic ulcer, and gastric carcinoma. In order to investigate the mechanisms of enhanced production of pepsinogen by H. pylori in cultured rat gastric cells that have the potential to produce pepsinogen, secretion and synthesis of pepsinogen in the cells exposed to H. pylori extract were determined by measuring the hydrolysis of hemoglobin. Various drugs were used to study the mechanisms of effects of H. pylori on the cells. Exposure of the gastric cells to H. pylori extract caused a significant increase in pepsinogen secretion into the culture medium within 30-180 min in a dose-dependent manner, accompanied by a significant increase in pepsinogen synthesis in the gastric cells after 60 min of incubation. Heat treatment of the H. pylori sonicate at 100 degrees C for 10 min completely abolished the stimulatory effect of H. pylori on pepsinogen secretion. 2',3'-Dideoxyadenosine (50 microM), a specific adenylate cyclase inhibitor, abolished the effect of H. pylori-induced pepsinogen secretion. Puromycin (10 microg/ml), a protein synthesis inhibitor, and nicorandil (0.1 mM), a specific intracellular calcium antagonist, reduced the H. pylori-induced pepsinogen secretion by 37% (p<0.01) and 25% (p<0.05), respectively. On the other hand, actinomycin D (1 microg/ml), an RNA synthesis inhibitor, did not affect the H. pylori-induced pepsinogen secretion. Consequently, dibutyryl cAMP potentially stimulated the pepsinogen secretion from gastric epithelial cells in a dose-dependent manner. H. pylori induces pepsinogen secretion and synthesis by gastric epithelial cells through an increase in the intracellular cAMP and mobilization of the intracellular calcium. In addition, H. pylori affects pepsinogen synthesis at the translational level.

Animals↗
PubMed2001

Reactivation of liver-specific gene expression in an immortalized human hepatocyte cell line by introduction of the human HNF4alpha2 gene.

An immortalized human hepatocyte cell line (OUMS-29) was established from fetal liver by transfection with the SV-40 large T antigen gene that has certain liver-specific functions such as albumin production and enzyme activities of CYP1A1, 1A2, and 2E1. To make OUMS-29 cells express other liver-specific functions, the human hepatocyte nuclear factor 4alpha2 (HNF4alpha2) gene was introduced into the cells, because this gene was found to be markedly down-regulated. The transduced HNF4alpha2 was overexpressed in the nuclei of the transfected cells, and its DNA-binding activity was also detected. The liver-specific genes such as apolipoprotein AI, CII, CIII, blood coagulation factor X, alpha1-antitrypsin, and HNF1alpha were up-regulated. Thus, this cell line is expected to be a useful tool for studying the differentiated human hepatocyte functions.

Apolipoprotein A-I↗
PubMed2001

Overexpression of platelet-derived growth factor B and downregulation of PDGF-receptor alpha in human immortalized fibroblasts.

Since immortalization of cells is critical in multistep carcinogenesis, efforts should be made to elucidate the mechanisms of the immortalization. To determine whether platelet-derived growth factor (PDGF) signal pathways play a role in immortalization of cells, we compared mRNA expressions of PDGFs and their receptors in three immortalized human fibroblast cell lines (SUSM-1, OUMS-24F, and KMST-6) with their normal parent cells. As a result, mRNA expression of PDGF-B (oncogene: c-sis) was upregulated in these immortalized cells. Unexpectedly, the expression of alpha- and beta-PDGF receptor genes was downregulated. PDGFR-alpha mRNA was remarkably decreased. When exogenous PDGFR-alpha was expressed transiently in the KMST-6 cells, the morphology of the cells resembled that of normal cells. These results suggest that the overexpression of PDGF-B (c-sis) and downregulation of PDGFR-alpha are related to the phenotypic characteristics of immortalized human cells.

Blotting, Northern↗
PubMed2001

Microsatellite instability correlates with normal expression of cyclin E in hepatocellular carcinomas.

It has been reported that microsatellite instability (MSI) strongly correlates with carcinogenesis and cancer progression. In the present study, we studied the incidence of MSI at 5 polymorphic microsatellite markers (D5S406, D13S153, D16S402, D17S796, and poly(A) tract BAT26), the expression of G1 cyclins (cyclin A, cyclin D and cyclin E), and Ki-67 labeling index in 30 surgically resected hepatocellular carcinomas (HCCs) and their adjacent non-cancerous tissues. The results of analysis showed that 43% of HCCs exhibited MSI in one locus, 10% in two loci, and 3% in three loci. Overexpressions of cyclin E and cyclin A were observed in 57% and 83% of HCCs, respectively. MSI in HCCs, however, correlated with normal expressions of cyclin E and cyclin A and with a low labeling index of Ki-67. Thus, patients with HCCs exhibiting MSI at these 5 markers may have less involvement of G1/S disregulation and may have better prognosis than other patients with HCC.

Aged↗
PubMed2001

Reduced expression of REIC/Dkk-3 gene in non-small cell lung cancer.

Dickkopfs (Dkks) are secretory glycoproteins and are important for inducing amphibian head formation. Some Dkks have the ability to antagonize the Wnt proto-oncoprotein, which can promote cell proliferation and transformation when it is mutated or overexpressed. We recently cloned the REIC/Dkk-3 gene, one of the Dkks, and found that expression of the gene was markedly decreased in many human immortalized and tumor-derived cell lines. To further investigate the function of the REIC/Dkk-3 gene in vivo, the gene expression was quantified in 57 surgically-resected non-small cell lung cancer (NSCLC) tissues and their adjacent normal lung tissues by real-time quantitative PCR analysis based on TaqMan methodology. The REIC/Dkk-3 mRNA level was significantly lower in NSCLC tissues than in normal lung tissues. Reduced expression of REIC/Dkk-3 in NSCLC was observed in 36 (63%) of the 57 tumors. Reduced expression of REIC/Dkk-3 was frequently observed in poorly differentiated adenocarcinoma and squamous cell carcinoma. These results indicate that reduced expression of REIC/Dkk-3 may be correlated with rapid cell proliferation in human NSCLC.

Adaptor Proteins, Signal Transducing↗
PubMed2001

Effects of oxygen concentrations on human fibroblasts treated with Fe(3+)-NTA.

Free radicals derived from the reaction of iron and oxygen are thought to be one of the causes of tissue injury. In order to identify whether oxygen concentrations are an important factor in iron-mediated damage to cells, cytotoxic effects of Fe(3+)-NTA on human fibroblasts (KMST-6 line) were studied under the conditions of 1% and 20% oxygen concentrations in an incubator. A comparison of the effects of Fe(3+)-NTA on cells cultured in 1% and 20% oxygen environments showed that the following features were more prominent under the usual culture concentrations of 20% oxygen: i) cytotoxicity, ii) increase in intracellular reactive oxygen species, iii) increase in H(2)O(2) production in the cells, and iv) formation of 8-hydroxydeoxyguanosine. To elucidate the roles of endogenous antioxidants, the levels of manganese superoxide dismutase (MnSOD) and catalase were measured by Western blotting. The increase in MnSOD in the presence of Fe(3+)-NTA was greater under the condition of 20% O(2) than under the condition of 1% O(2). The expression of catalase was significantly up-regulated at 20% O(2). However, when the cells were treated with Fe(3+)-NTA, the expression of catalase was markedly down-regulated under the condition of 20% O(2). Hydroxyl radical scavengers such as vitamin E, dimethyl-sulfoxide (DMSO) and mannitol reduced endogenous ROS generation and alleviated the cytotoxic effects of iron. On the other hand, superoxide dismutase (SOD), vitamin C and catalase did not show any protective effects against Fe(3+)-NTA. These findings suggest that enhanced cytotoxic effects of Fe(3+)-NTA at 20% O(2 )are due to endogenously produced hydroxyl radicals.

8-Hydroxy-2'-Deoxyguanosine↗
PubMed2001

[Clinical evaluation of roxatidine acetate hydrochlorides as a preanesthetic medication].

Roxatidine acetate hydrochloride capsule is slowly absorbed from the gastrointestinal tract, and its acid suppressive effect on the stomach is long-lasting compared with other H2-blockers. The reduction of gastric juice in perioperative period is considered advantageous for patients not only because it decreases the risk for aspiration pneumonia but also because it reduces the risk of bronchial spasm induced by gastroesophageal reflux of acidic gastric content. The effects of single oral administration of roxatidine acetate hydrochloride 150 mg at night before the operation on the volume and pH of gastric juice were investigated during anesthesia using two types of anesthetic agents (isoflurane and propofol) in 93 patients of three age groups (group Y: age 20-40, group M: age 41-64, group O: age 65 <). The effect of roxatidine on reduction of gastric juice was found at the time of anesthetic induction and 2 hours after the induction in any age group with either anesthetic agent. The serum concentration of roxatidine at the time of induction was much higher in group O. The value of residual concentration of roxatidine 20 hours after oral intake was estimated from the intraoperative measurements of serum concentration. The results suggest that single administration at night before the operation is sufficient for the oldest group, but an additive dose is recommended for the younger groups.

Adult↗
PubMed2001

Insertion of a suicide gene into an immortalized human hepatocyte cell line.

For developing a bioartificial liver (BAL) device, an attractive alternative to the primary human hepatocytes would be the use of highly differentiated immortalized human hepatocytes with a safeguard. To test the feasibility, the primary human hepatocytes were immortalized by a plasmid SV3neo encoding simian virus 40 large T antigen (SV40Tag) gene. A highly differentiated hepatocyte line OUMS-29 was established. A suicide gene of herpes simplex virus-thymidine kinase (HSV-TK) was retrovirally introduced into OUMS-29 cells as a safeguard for clinical application. One of the resulting HSV-TK-positive cell lines, OUMS-29/tk, grew in chemically defined serum-free medium with the gene expression of differentiated liver functions. OUMS-29/tk cells were 100 times more sensitive to ganciclovir compared with unmodified OUMS-29 cells in in vitro experiments. We have established a tightly regulated immortalized human hepatocyte cell line. Essentially unlimited availability of OUMS-29/tk cells may be clinically useful for BAL therapy.

Antiviral Agents↗
PubMed2001

[Insulin aspart(NN-X14)].

Insulin aspart is a novel rapid-acting human insulin analogue, which structure is almost identical to human insulin, except for the substitution of a single residue in the amino acid sequence of the insulin. The structure of insulin aspart leads to more rapid absorption than human insulin. As a result, insulin aspart provides significantly better postprandial glucose control than human insulin. As mealtime insulin in a basal-bolus regimen, insulin aspart gives stable 24-hour blood glucose control, with lower maximum glucose levels during daytime than with human insulin. The better daily glycaemic profile with insulin aspart gives the better long-term metabolic control estimated by HbA1C. The score of patients' satisfaction in DTSQ(Diabetes Treatment Satisfaction Questionnaire) was greater with insulin aspart treatment. The overall safety of insulin aspart is comparable to human insulin.

Blood Glucose↗
PubMed2000

Hepatocyte growth factor induces differentiation of adult rat bone marrow cells into a hepatocyte lineage in vitro.

Bone marrow (BM) cells originally include alpha-fetoprotein (AFP)- and c-Met [a receptor for hepatocyte growth factor (HGF)]-expressing cells. In vitro treatment of BM cells with HGF induced albumin-expressing hepatocyte-like cells. Furthermore, those hepatocyte-like cells expressed cytokeratins 8 and 18, which are typically expressed in normal adult hepatocytes. These findings demonstrate that BM cells include AFP-expressing hepatic progenitor cells that can be differentiated into hepatocytes by HGF in culture, indicating that such cultures are useful resources for cell transplantation therapy for liver diseases.

Animals↗
PubMed2000

Morphological alteration of X-ray induced partially transformed human cells by transfection with a small c-myc DNA sequence.

During attempts to transform a normal human fibroblast strain (GM730) by X-irradiation, we obtained a partially transformed cell strain (GM730pt) which demonstrates several aspects of the transformed phenotype including morphological changes, increased saturation density, growth in soft agar, and focus formation in long-term cultures. When GM730pt cells were transfected with the feline c-myc gene, morphology of the cells changed dramatically following seven days of expression. Transfection of other plasmid DNAs or oncogenes such as pUC8, pSV2neo, src, sis, and H-ras had little or no effects on the phenotype of GM730pt cells. On the other hand, a gel purified, small fragment of c-myc DNA had a complete cell alteration activity. Furthermore, Bal 31 deletion and M13 sequencing experiments showed that the alteration seen in GM730pt cells is delimited to a 24 nucleotide stretch (active myc element) from the second intron of the feline c-myc gene that contains a T-rich sequence.

Agar↗
PubMed2000

Relationship between contact inhibition and intranuclear S100C of normal human fibroblasts.

Many lines of evidence indicate that neoplastic transformation of cells occurs by a multistep process. For neoplastic transformation of normal human cells, they must be first immortalized and then be converted into neoplastic cells. It is well known that the immortalization is a critical step for the neoplastic transformation of cells and that the immortal phenotype is recessive. Thus, we investigated proteins downregulated in immortalized cells by two-dimensional gel electrophoresis. As a result, S100C, a Ca(2+)-binding protein, was dramatically downregulated in immortalized human fibroblasts compared with their normal counterparts. When the cells reached confluence, S100C was phosphorylated on threonine 10. Then the phosphorylated S100C moved to and accumulated in the nuclei of normal cells, whereas in immortalized cells it was not phosphorylated and remained in the cytoplasm. Microinjection of the anti-S100C antibody into normal confluent quiescent cells induced DNA synthesis. Furthermore, when exogenous S100C was compelled to localize in the nuclei of HeLa cells, their DNA synthesis was remarkably inhibited with increase in cyclin-dependent kinase inhibitors such as p16(Ink4a) and p21(Waf1). These data indicate the possible involvement of nuclear S100C in the contact inhibition of cell growth.

Amino Acid Sequence↗
PubMed2000

A REIC gene shows down-regulation in human immortalized cells and human tumor-derived cell lines.

Normal human cells stop proliferation after a certain number of cell divisions. This phenomenon is called cellular aging. The fact that the senescence phenotype is dominant and the immortal one is recessive indicates that immortalization of human cells may be caused by loss of functions of certain genes in normal cells. Based on this evidence, several cDNA clones whose expression was down-regulated during the immortalization process of human cells were isolated by the representative difference analysis (RDA) system in our laboratory. One of them, which was named REIC, was expressed to a lower degree in three human immortalized cell lines as compared with their parental normal counterparts. In addition, the expression of REIC was markedly lower in eight human tumor-derived cell lines (Hep3B and HuH-7 hepatocellular carcinomas, HuH-6 Clone 5 hepatoblastoma, HuCCT-1 cholangiocarcinoma, A549 lung cancer, HaCaT immortalized keratinocyte, HeLa cervical carcinoma, and Saos-2 osteosarcoma). In contrast, among the human tissues examined, the heart and brain, which contain a large number of post-mitotic cells, showed the highest expression of REIC. The full-length REIC cDNA revealed that the predicted protein is 350 amino acids in length and possesses coiled-coil tertiary structures in each of the amino- and carboxyl-termini. Furthermore, a search of the protein database revealed a match of this gene product with Dkk-3, which is a novel inhibitor of Wnt oncogene. These results indicate that the REIC cloned by us may function as a tumor suppressor.

Adaptor Proteins, Signal Transducing↗
PubMed2000

Transplantation of highly differentiated immortalized human hepatocytes to treat acute liver failure.

BACKGROUND: Temporary support of a damaged liver by a bioartificial liver (BAL) devise is a promising approach for the treatment of acute liver failure. Although human primary hepatocytes are an ideal source of hepatic function in BAL, shortage of human livers available for hepatocyte isolation is the limiting factor for the use of this modality. A clonal human hepatocyte cell line that can grow economically in culture and exhibit liver-specific functions should be an attractive solution to this problem. METHODS: To test this alternative, primary human fetal hepatocytes were immortalized using Simian virus 40 large T antigen. To investigate the potential of the immortalized cells for BAL, we transplanted the cells into the spleen of adult rats and performed a 90% hepatectomy 12 hr later. RESULTS: One of the cloned human liver cell lines, OUMS-29, showed highly differentiated liver functions. Intrasplenic transplanting of 20x10(6) OUMS-29 cells protected the animals from hyperammonemia and the associated hepatic encephalopathy. Survival was significantly prolonged in 90% of hepatectomized rats receiving OUMS-29 cells. CONCLUSIONS: A highly differentiated immortalized human hepatocyte cell line, OUMS-29, was able to provide metabolic support during acute liver failure induced by 90% hepatectomy in rats. Essentially unlimited availability of OUMS-29 cells may be clinically useful for BAL treatment.

Ammonia↗
PubMed2000

Establishment of a human hepatoma cell line, HLE/2E1, suitable for detection of p450 2E1-related cytotoxicity.

By transfection of an expression vector of human cytochrome P450 2E1 (CYP2E1) into a human hepatoma cell line (HLE), a new cell line (HLE/2E1) that stably expresses activity of CYP2E1 has been established. The HLE/2E1 cell line expressed a higher level of CYP2E1 messenger ribonucleic acid than did the mother HLE cell line. CYP2E1 enzyme activity determined by a p-nitrophenol oxidation assay was also higher in HLE/2E1 cells than in HLE cells. In addition, the enzyme activity of the HLE/2E1 cells was increased by ethanol treatment. Exposure to acetaminophen (APAP) or buthionine sulfoximine (BSO) caused a greater decrease in viability of the HLE/2E1 cells than that of the HLE cells, as determined by the 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide assay. The cytotoxicity of APAP or BSO to HLE/2EI cells was inhibited by the addition of ethanol or vitamin E. However, the cytotoxicity of both APAP and BSO was enhanced by 24-h preincubation of HLE/2E1 cells with ethanol. These results show that this cell line provides a useful model for studying catalytic properties of CYP2E1 and cytotoxic mechanisms of chemicals metabolized by CYP2E1.

Acetaminophen↗