Intrasplenic transplantation of immortalized human fetal hepatocytes prolongs the survival of 90% hepatectomized rats.
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Ammonia↗
Biomedical subjects
M Namba
Publications and source records attributed to M Namba.
Establishment of a highly differentiated immortalized human hepatocyte cell line as a source of hepatic function in the bioartificial liver.
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Ammonia↗
In vitro aging research in Japan.
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Aging↗
An autopsy case of postencephalitic parkinsonism of von Economo type: some new observations concerning neurofibrillary tangles and astrocytic tangles.
An autopsied case of postencephalitic parkinsonism of von Economo type with a 71-year duration is reported. Several cases of postencephalitic parkinsonism of von Economo type have been reported in Japan but this is the first reported case from western Japan. The patient was a Japanese man who was 74 years of age at the time of death. He developed encephalitis of unknown etiology at the age of 3 years. The first symptom was antisocial behavior, which developed at 30 years of age. At the age of 40 years, the patient showed progressive parkinsonism. Neuropathological findings disclosed marked neuronal loss with gliosis in the substantia nigra, locus ceruleus, and raphe nuclei, as well as the appearance of neurofibrillary tangles in the aforementioned areas. There were also widespread tuft-shaped astrocytes (Tu-SA) in the central nervous system, including the thalamus. Tuft-shaped astrocytes are considered to represent non-reactive astrocytes because the distributions of neurofibrillary tangles (NFT) and Tu-SA are clearly different. Therefore, the primary astrocytic lesions in postencephalitic parkinsonism of von Economo type may be more widespread. Ultrastructurally, the Tu-SA consisted of straight filaments, 15 nm in width, which formed tight bundles. Ultrastructurally, NFF in this case revealed paired helical filaments but straight filaments, 15 nm in width, which were also found in the neurons of the substantia nigra.
Aged↗
Important role of angiotensin II-mediated c-Jun NH(2)-terminal kinase activation in cardiac hypertrophy in hypertensive rats.
In vitro studies on the role of the mitogen-activated protein (MAP) kinase family (extracellular signal-regulated kinase [ERK], c-Jun NH(2)-terminal kinase [JNK], and p38) in cardiac hypertrophic response have produced confusing and contradictory results. We examined the in vivo role of the angiotensin II type 1 (AT(1)) receptor in cardiac MAP kinase activities during both the onset and development of cardiac hypertrophy in stroke-prone spontaneously hypertensive rats (SHRSP). In both the acute and chronic phases of cardiac hypertrophy in SHRSP, cardiac JNK activities were significantly increased compared with those in normotensive rats, whereas there was no prominent increase in cardiac ERK or p38 activities in SHRSP. Losartan, an AT(1) receptor antagonist, prevented the onset of cardiac hypertrophy and regressed the progression of cardiac hypertrophy in SHRSP, being accompanied by the reduction of JNK activity and activator protein-1 (AP-1) activity in SHRSP. However, in spite of the normalization of blood pressure, hydralazine did not prevent or regress cardiac hypertrophy and did not decrease JNK or AP-1 activity in SHRSP. Inversely, hydralazine significantly increased the cardiac ERK activity in SHRSP by enhancing its phosphorylation. In conclusion, we have obtained the first evidence that the AT(1) receptor is involved in the enhanced cardiac JNK activity in both the onset and development of cardiac hypertrophy of hypertensive rats. We propose that JNK is involved in AT(1) receptor-mediated cardiac hypertrophy in vivo, in part mediated by the activation of AP-1.
Acute Disease↗
Stable overexpression of the glucose-6-phosphatase catalytic subunit attenuates glucose sensitivity of insulin secretion from a mouse pancreatic beta-cell line.
Glucose-6-phosphatase (G-6-Pase) hydrolyzes glucose-6-phosphate to glucose, reciprocal with the so-called glucose sensor, glucokinase, in pancreatic beta cells. To study the role of G-6-Pase in glucose-stimulated insulin secretion from beta cells, we have introduced rat G-6-Pase catalytic subunit cDNA and have established permanent clones with 3-, 7- and 24-fold G-6-Pase activity of the mouse beta-cell line, MIN6. In these clones, glucose usage and ATP production in the presence of 5.5 or 25 mM glucose were reduced, and glucose-stimulated insulin secretion was decreased in proportion to the increased G-6-Pase activity. In addition, insulin secretory capacity in response to d-fructose and pyruvate was unchanged; however, 25 mM glucose-stimulated insulin secretion and intracellular calcium response were completely inhibited. In the clone with 24-fold G-6-Pase activity, changes in intracellular NAD(P)H autofluorescence in response to 25 mM glucose were reduced, but the changes with 20 mM fructose and 20 mM pyruvate were not altered. Stable overexpression of G-6-Pase in beta cells resulted in attenuation of the overall glucose-stimulated metabolic responses corresponding to the degree of overexpression. This particular experimental manipulation shows that the possibility exists of modulating glucose-stimulated insulin release by thoroughly altering glucose cycling at the glucokinase/G-6-Pase step.
Adenosine Triphosphate↗
Recombinant human betacellulin promotes the neogenesis of beta-cells and ameliorates glucose intolerance in mice with diabetes induced by selective alloxan perfusion.
Betacellulin (BTC), a member of the epidermal growth factor family, is expressed predominantly in the human pancreas and induces the differentiation of a pancreatic acinar cell line (AR42J) into insulin-secreting cells, suggesting that BTC has a physiologically important role in the endocrine pancreas. In this study, we examined the in vivo effect of recombinant human BTC (rhBTC) on glucose intolerance and pancreatic morphology using a new mouse model with glucose intolerance induced by selective alloxan perfusion. RhBTC (1 microg/g body wt) or saline was injected subcutaneously every day from the day after alloxan treatment. The intraperitoneal glucose tolerance test revealed no difference between rhBTC-treated and rhBTC-untreated glucose-intolerant mice at 2-4 weeks. However, glucose tolerance was significantly improved and body weight was significantly increased in rhBTC-treated mice compared with untreated mice at 8 weeks. Islet-like cell clusters, consisting mainly of beta-cells, were increased in the pancreas and were localized in contact with the ductal lining cells and sometimes with acinar cells. In conclusion, administration of rhBTC improved glucose tolerance in this mouse model by increasing beta-cell volume, primarily through accelerated neogenesis from ductal lining cells.
Animals↗
Growth inhibitory effects of ATP and its derivatives on human fibroblasts immortalized with 60Co-gamma rays.
In our previous study (Katayama B et al, Int J Mol Med 2: 603-606, 1998), cell growth inhibition caused by ATP added to cultures was found to be greater in immortalized human fibroblasts than in the normal human fibroblasts. Since it has been reported that ATP affects cells via P2-purinergic receptors, growth inhibitory effects of ATP and its derivatives on immortalized human fibroblasts were investigated in the present study in order to learn what type of receptors are involved in ATP cytotoxicity. The ATP derivatives used in this study were: ATP, ADP, beta, gamma-methyleneadenosine 5'-triphosphate (MeATP), 2' & 3'-o-(4-benzoylbenzoyl) adenosine, triethylammonium salt (BzATP), adenosine 5'-o-(3-thiotriphosphate) (ATPgammaS), 2-methylthioadenosine 5'-triphosphate (2-MeSATP) and UTP. The extent of cytotoxicity induced by these drugs was found to be in the order of: ATP=ADP>ATPgammaS>MeATP=BzATP. On the other hand, neither 2-MeSATP nor UTP showed any cytotoxicity. These findings indicate that ATP may exert the cell growth inhibition by certain kinds of signal transduction via P2x or P2y purinergic receptors which affect intrinsic channels/pores of cell membrane and/or G protein activation. As a result, intracellular elevation in the concentrations of ions such as calcium and potassium, membrane depolarization, loss of endogenous ions/metabolites, and activation of inositol phospholipid-specific phospholipase C may occur. Actually, a dihydropyridine calcium channel blocker, nifedipine, and an ATP-sensitive K+-channel blocker, glybenclamide, reduced the growth inhibitory effects of ATP on the cells to some extent. The growth inhibition caused by ATP was not due to apoptosis or induction of a cyclin/CDK kinase inhibitor, P21.
Adenosine Triphosphate↗
Different expression of positive and negative regulators of hepatocyte growth in growing and shrinking hepatic lobes after portal vein branch ligation in rats.
Portal vein branch embolization is often performed before hepatectomy to prevent postoperative liver failure. It is, however, still not clear how the embolized lobe shrinks and the non-embolized lobe proliferates in counterbalance. We investigated the expression of positive and negative regulators of hepatocyte growth to clarify the mechanisms of liver growth and atrophy in a rat portal vein ligation (PVL) model compared with partial hepatectomy (PH). A significant increase in DNA synthesis within the non-ligated lobe reached a peak at 36 h, a delay of 12 h as compared with PH, while no increase occurred in the ligated lobe. Expression of hepatocyte growth factor mRNA remarkably increased in the non-ligated growing lobe between 6 and 24 h, but was only slightly elevated in the ligated shrinking lobe. Contrarily, negative regulators of hepatocyte proliferation, such as TGF-beta1 and IL-1beta, were strongly expressed in the ligated shrinking lobe. Thus, the changes of portal venous flow and/or pressure caused by PVL may contribute to induction of different kinds of growth factors between the ischemic and non-ischemic lobes; these factors possibly regulate liver regeneration and atrophy after PVL.
Animals↗
High frequency of tetraploidy detected in malignant melanoma of Japanese patients by fluorescence in situ hybridization.
Aneuploidy and hyperploidy are often detected in malignant melanoma by cytogenetic analysis and flow cytometric analysis of DNA content. To determine the ploidy of cells in surgical specimens of melanin-producing tumors of Japanese patients, we performed fluorescence in situ hybridization (FISH) using touch smear technique to count the number of chromosomes 18 and X + Y in interphase nuclei using alpha-satellite DNA probes, D18Z1, DXZ1 and DYZ3. A normal melanocyte strain showed two D18Z1 and two [DXZ1+DYZ3] signals per nucleus, indicating 2N, and a malignant melanoma cell line showed 4 per nucleus, indicating 4N, consistent with results of cytogenetic and flow cytometric analyses. Therefore we employed this FISH method to analyze ploidy of surgical specimens. Specimens obtained from 8 patients with nevus cell nevus showed 2 FISH signals per nucleus. On the other hand, in all specimens obtained from 8 patients with malignant melanoma (6 primary and 2 metastatic melanoma), 65-90% of cells exhibited 4 signals per nucleus, indicating 4N. Histopathologically, 50-70% of cells were identified as malignant melanoma cells, indicating that our FISH method is effective to detect melanoma cells in tissue. We also analyzed allelic loss of the p53 gene by FISH with a p53 locus-specific probe and mutation of the p53 gene by immunostaining since mutation and deletion of the p53 gene may cause hyperploidy. All specimens except one obtained from a case with young-onset metastatic melanoma exhibited no allelic losses or negative p53 staining, showing the p53 gene was intact. These results indicate that tetraploidy, not caused by p53 mutation or deletion, is commonly found in malignant melanoma of Japanese patients. It is also suggested that there is no positive relationship between tetraploidy and poorer prognosis, and mutation and allelic loss of the p53 gene might be markers of aggressive form of malignant melanoma.
Adult↗
[Heart rate reduction using edrophonium during coronary artery bypass grafting without cardiopulmonary bypass].
Coronary artery bypass grafting without the use of cardiopulmonary bypass (CPB) is performed with increasing frequency. Performing revascularization on a beating heart is technically more demanding than performing revascularization on the arrested heart, especially in high-risk patients. beta-Blockers and calcium-channel antagonists have been used for the reduction of heart rate (HR) for the local immobilization of the anastomotic site. However, their negative inotropic actions often lead to serious hypotension. Therefore, we investigated the effect of edrophonium on HR reduction in high-risk patients undergoing CABG without CPB. Ten high-risk patients undergoing CABG without CPB were selected. To reduce HR during anastomosis, edrophonium was administered during the procedure. Systemic blood pressure (sBP), HR, and cardiac index (CI) were measured from the induction of anesthesia to the end of surgery. All surgeries were successfully performed without serious complications. To keep the rate under 60 bpm, edrophonium was administered at the time of anastomosis and this decreased the cardiac index from 2.19 to 1.95, while the sPB was maintained easily over 90 mmHg with the infusion of methoxamine. Edrophonium may be useful for the reduction of HR during coronary anastomosis in high-risk patients undergoing CABG without CPB.
Aged↗
Structure/function studies of hepatocyte nuclear factor-1alpha, a diabetes-associated transcription factor.
Mutations in the transcription factor hepatocyte nuclear factor-1alpha (HNF-1alpha) cause maturity-onset diabetes of the young type 3 (MODY3), a form of diabetes mellitus characterized by autosomal dominant inheritance, early onset, and pancreatic beta-cell dysfunction. We have examined the effects of five diabetes-associated mutations (L12H, G191D, R263C, P379fsdelCT, and L584S585fsinsTC) on HNF-1alpha function including DNA binding ability, intracellular localization, and transactivation activity. L12H, P379fsdelCT, and L584S585fsinsTC mutations were found in patients with a clinical diagnosis of MODY, while G191D and R263C mutations were identified in patients diagnosed with type 2 diabetes. These mutations had diverse effects on the functional properties of HNF-1alpha. Comparison of the functional data with clinical information suggested that transactivation activity of mutant HNF-1alpha in beta cells like MIN6 may be the primary determinants of the phenotypic differences observed among diabetic patients with HNF-1alpha mutations.
Adolescent↗
Manumycin A, inhibitor of ras farnesyltransferase, inhibits proliferation and migration of rat vascular smooth muscle cells.
Restenosis after angioplasty is thought to be caused by proliferation and migration of vascular smooth muscle cells (VSMCs), and it is a most serious problem in medical treatment. A low dose (50 ng/ml) of manumycin A, an inhibitor of p21(ras) (ras) farnesylation, significantly inhibited proliferation of rat VSMCs stimulated by the platelet-derived growth factor (PDGF). The mitoinhibitory effect of manumycin A was dose- and time-dependent but was independent of cell density. Western blot analysis showed that manumycin A reduced the amount of functional ras localized at the cytoplasmic membrane and inhibited the phosphorylation of p42/44 mitogen-activated protein kinase (MAPK). Manumycin A also inhibited VSMC migration and disorganized alpha actin fibers, as shown by immnofluorecence staining. These results indicate that the interruption of the ras/MAPK signal transduction pathway and the disorganization of alpha actin fibers are the main cause of manumycin A inhibition of VSMC proliferation and migration induced by PDGF.
Alkyl and Aryl Transferases↗
Human insulin gene is a target gene of hepatocyte nuclear factor-1alpha (HNF-1alpha) and HNF-1beta.
Maturity-onset diabetes of the young (MODY) is a monogenic form of diabetes characterized by autosomal dominant inheritance, early-onset, and impaired insulin secretion. The type 3 and type 5 forms of MODY result from mutations in the genes encoding the transcription factor, hepatocyte nuclear factor (HNF)-1alpha and HNF-1beta, respectively. The mechanism by which mutations in one allele of the HNF-1 gene impair pancreatic beta cell function is unclear. We studied the effects of wild-type and four mutant (L12H, R263C, P379fsdelCT, and L584S585fsinsTC) HNF-1alpha, which were identified in Japanese subjects with MODY3 on human insulin gene transcription. Both wild-type (WT) HNF-1alpha and HNF-1beta bound to the oligonucleotide containing the A3 element sequence in the human insulin promoter and transactivated the insulin-luciferase reporter gene by 30- and 31-fold, respectively. In contrast, binding of L12H, R263C and L584S585fsinsTC-HNF-1alpha to the probe was impaired. Transactivation activity by the four mutant HNF-1alpha was reduced (4.3 to 43.3% of WT). These data suggest that the insulin gene is a candidate target gene of HNF-1alpha/HNF-1beta and the impairment of insulin gene transcription by mutations in the HNF-1 gene might be involved in the pathogenesis of MODY.
Animals↗
Enhanced activity of cyclin A-associated kinase in immortalized human fibroblasts.
Deregulation of cell cycle regulatory mechanisms leads to disruption of normal control of cell growth and may be associated with neoplastic transformation. To determine whether immortalized human cells have alterations in their cell cycle regulatory mechanisms, we analyzed cell cycle regulatory proteins in 2 immortalized human fibroblast cell lines, KMST-6 and OUMS-24/P6X, established by repeated irradiation with (60)Co gamma rays alone or mutant p53 gene transfection plus X-ray irradiation, respectively. Both the immortalized cell lines had markedly enhanced activity of cyclin A-associated kinase as compared with their normal counterparts. The high activity of cyclin A-associated kinase was well correlated with the increased expression of cyclin A mRNA and its protein. In addition, the immortalized cell lines showed significantly reduced amounts of p21(Cip1/Waf1/Sdi1), a potent inhibitor of cyclin dependent kinases. Furthermore, among the pRb family of proteins, p107 and p130, were hyperphosphorylated in both the immortalized cell lines, suggesting possible participation in upregulation of cyclin A associated kinase activity. These changes represent some important characteristics of immortalized cells.
Blood Proteins↗
Electrophoretic and serologic characterization of 56 kDa antigen (M56) with autologous serum derived from a chondrosarcoma patient: a shared antigen of immunoresponses in cancer and autoimmune diseases.
We investigated whether antibodies specific to autologous cancer cells are produced in the peripheral blood of patients with chondrosarcoma. There have been few reports on the investigation of the immune responses, such as autologous antibody production, to chondrosarcoma. Here, tumor-associated antigens were separated by sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis and detected by immunoenzymatic amplification. A 56 kDa molecule (M56) was detected in the serum from patients' peripheral blood. M56 is ubiquitously expressed in various kinds of tissue-derived cells. However, the molecule seemed to be retained mostly in the cytosolic compartment of lymphoid cells, while it was expressed on the cell surface of nonlymphoid cancer cells. Furthermore, the antibodies reactive to the 56 kDa molecule were frequently observed in sera derived from patients with other cancers and autoimmune diseases as compared to the sera from healthy control donors, suggesting that M56 is a common target molecule of immune responses in patients with various cancers and autoimmune diseases.
Animals↗
Immunological abnormalities in islets at diagnosis paralleled further deterioration of glycaemic control in patients with recent-onset Type I (insulin-dependent) diabetes mellitus.
AIMS/HYPOTHESIS: To determine whether the clinical heterogeneity observed in the development of Type I (insulin-dependent) diabetes mellitus correlates with immunohistochemical differences observed at diagnosis. METHODS: Patients (n = 17) with recent-onset diabetes clinically considered to be insulin dependent (Type I), underwent pancreatic biopsy for immunohistological analysis. These patients were divided into two groups based on the presence or absence of islet immunological abnormalities (insulitis or hyperexpression of MHC class I antigens or both). The patients were also HLA typed and tested for islet cell antibodies and antibodies to glutamic acid decarboxylase (GAD-Ab). All patients were followed monthly for 2 years and their fasting plasma glucose, haemoglobin A1c and daily insulin doses were recorded. The clinical course of patients with islet immunological abnormalities was compared with that of patients without those abnormalities. RESULTS: Patients with and without islet immunological abnormalities did not differ with regard to HLA type or islet cell antibodies. Antibodies to glutamic acid decarboxylase correlated with the presence of insulitis and MHC class I hyperexpression. These local immunological abnormalities were also associated with higher haemoglobin A1c values (p < 0.05) and a trend towards greater insulin requirements. Further, patients with the islet abnormalities had higher fasting plasma glucose concentrations 2 years after the biopsy than at the time of the biopsy (p < 0.05). CONCLUSION/INTERPRETATION: The heterogeneous clinical course observed following diagnosis in patients with Type I diabetes correlates with islet immunological abnormalities. Insulitis and hyperexpression of MHC class I correlate with deteriorating glycaemic control.
Adolescent↗
Three new mutations in the hepatocyte nuclear factor-1alpha gene in Japanese subjects with diabetes mellitus: clinical features and functional characterization.
AIMS/HYPOTHESIS: Mutations in the hepatocyte nuclear factor-1alpha gene are a common cause of the type 3 form of maturity-onset diabetes of the young. We examined the clinical features and molecular basis of hepatocyte nuclear factor-1alpha (HNF-1alpha) diabetes. METHODS: Thirty-seven Japanese subjects with early onset Type II (non-insulin-dependent) diabetes mellitus and 45 with Type I (insulin-dependent) diabetes mellitus were screened for mutations in this gene. Functional properties of mutant HNF-1alpha were also investigated. RESULTS: Three new mutations [G415R, R272C and A site of the promoter (+ 102G-to-C)] were found. Insulin secretion was impaired in the three subjects. Insulin and glucagon secretory responses to arginine in the subject with the R272C mutation were also diminished. Molecular biological studies indicated that the G415R mutation generated a protein with about 50% of the activity of wild-type HNF-1alpha. The R272C mutation had no transactivating or DNA binding activity and acted in a dominant negative manner. The + 102 G-to-C mutation in the A site of the promoter activity was associated with an increase in promoter activity and it had 42-75% more activity than the wild-type sequence. CONCLUSION/INTERPRETATION: Mutations in the HNF-1alpha gene may affect the normal islet function by different molecular mechanisms.
Adult↗