Search PubMed⌕ Search

Biomedical subjects

M Takemura

Publications and source records attributed to M Takemura.

At least 55 records · Page 3Linked to original sources
PubMed2001

The carboxyl terminal sequence of nucleolar protein B23.1 is important in its DNA polymerase alpha-stimulatory activity.

The protein B23 is a major nucleolar phosphoprotein comprising two isoforms, B23.1 and B23.2, which differ only in their carboxyl-terminal short sequences, the N-terminal 255 residues being identical in both forms. Both B23.1 and B23.2 stimulated immunoaffinity-purified calf thymus DNA polymerase alpha in a dose-dependent manner. The stimulatory effect of protein B23.1, the longer isoform, was found to be 2-fold greater than that of B23.2. Purified DNA polymerase alpha bound tightly to a protein B23.1-immobilized column, while it bound weakly to a protein B23.2-immobilized column. Surface plasmon resonance studies by BIAcore further showed that protein B23.1 bound to the DNA polymerase alpha-(dA).(dT) complex more tightly than did protein B23.2. The protein B23 isoforms appear to interact directly with the DNA polymerase alpha protein and not through the bound nucleic acid. These observations indicated that protein B23 physically bound to the DNA polymerase alpha and stimulated the enzyme activity. Product analyses showed that protein B23 greatly enhanced the reaction both in amount and length of product DNA, whereas it did not significantly alter the processivity of polymerization. In contrast, protein B23 effectively protected DNA polymerase alpha from heat inactivation. These results suggest that protein B23 stabilizes DNA polymerase alpha that is detached from product DNA, allowing the enzyme to be recruited for further elongation. Moreover, experiments using various C-terminal deletion mutants of protein B23 indicated that 12 amino acids at the C-terminal end of B23.1, which are absent in B23.2, may be essential for the full stimulation of the DNA polymerase alpha.

Amino Acid Sequence↗
PubMed2001

Galactosyldiacylglycerol, a mammalian DNA polymerase alpha-specific inhibitor from a sea alga, Petalonia bingbamiae.

The glycolipid galactosyldiacylglycerol (GDG), containing C16:0 and C18:1 fatty acids, was isolated from the sea alga Petalonia bingbamiae as a potent inhibitor of the activities of mammalian DNA polymerase alpha (pol. alpha). GDG, however, had no effect on pol. alpha from a fish or a higher plant. The inhibition of pol. alpha by GDG was dose-dependent with an IC50 value of 54 microM. The compound did not influence the activities of other replicative DNA polymerases such as mammalian pol. delta, or repair-related enzymes such as mammalian pol. beta. GDG also did not influence the activities of prokaryotic DNA polymerases such as the Klenow fragment of DNA polymerase I, T4 DNA polymerase, Taq DNA polymerase, DNA polymerases from the higher plant, cauliflower, or DNA metabolic enzymes such as calf thymus terminal deoxynucleotidyl transferase, human immunodeficiency virus type 1 reverse transcriptase and deoxyribonuclease 1. Kinetic analysis of the compound showed that pol. alpha was non-competitively inhibited with respect to both the DNA template and the nucleotide substrate. In this study, we demonstrated the structure-function relationship in the selective inhibition of pol. alpha by the glycolipid group.

Animals↗
PubMed2001

Guinea pig histamine N-methyltransferase: cDNA cloning and mRNA distribution.

We report here the isolation of histamine N-methyltransferase (HMT) cDNA from the guinea pig brain by the polymerase chain reaction on the basis of nucleotide sequences of rat and human counterparts. Guinea pig HMT consists of 292 amino acids, with homologies of 75.6% and 79.1% to rat and human HMT, respectively. Northern blotting analysis indicated that the 1.6-kb guinea pig HMT transcript was expressed at various levels in different tissues at the following relative abundance: jejunum, brain > lung, spleen, stomach > liver, kidney. HMT mRNA localized throughout the jejunum, and it was mainly expressed in epithelial cells and in Auerbach's plexus.

Amino Acid Sequence↗
PubMed2001

3-Hydroxyanthranilic acid, an L-tryptophan metabolite, induces apoptosis in monocyte-derived cells stimulated by interferon-gamma.

3-Hydroxyanthranilic acid (3-HAA), a metabolite of L-tryptophan, accumulates in monocyte-derived cells (THP-1), but not in other cell lines tested (MRC-9, H4, U373MG, Wil-NS), following immune stimulation that induces indoleamine-2,3-dioxygenase (IDO), a rate-limiting enzyme in the L-tryptophan kynurenine pathway. We examined whether metabolites of the L-tryptophan-kynurenine pathway act to induce apoptosis in monocytes/macrophages. Of the L-tryptophan metabolites tested, only 3-HAA at a concentration of 200 micromol/L was found to induce apoptosis in THP-1 and U937 cells. The addition of ferrous or manganese ions further enhanced apoptosis and free radical formation by 3-HAA in these two types of cells. The apoptotic response induced by 3-HAA was significantly attenuated by the addition of antioxidant, alpha-tocopherol or Trolox (a water-soluble analogue of vitamin E), and the xanthine oxidase inhibitor, allopurinol. In addition, the 3-HAA-induced apoptotic response was slightly attenuated by catalase, but not by superoxide dismutase (SOD), indicating that generation of hydrogen peroxide is involved in this response. Interferon-gamma (IFN-gamma), an inducer of IDO, potently induced apoptosis in THP-1 cells, but not in U937 cells, in the presence of ferrous or manganese ions. This different susceptibility to apoptosis inducer between THP-1 and U937 cells may depend on the capacity of the cells for 3-HAA synthesis following IDO induction by IFN-gamma. Furthermore, apoptosis was suppressed by cycloheximide in THP-1 cells, suggesting that newly synthesized proteins may be essential for apoptotic events. These results suggest that 3-HAA induces apoptosis in monocytes/macrophages under inflammatory or other pathophysiological conditions.

3-Hydroxyanthranilic Acid↗
PubMed2001

Cost-effectiveness analysis of dopamine agonists in the treatment of Parkinson's disease in Japan.

BACKGROUND: Dopamine agonists such as bromocriptine or pergolide are often used in Japan to treat Parkinson's disease. Dopamine agonists are relatively expensive drugs; economic evaluations are required. OBJECTIVE: To evaluate the cost effectiveness of dopamine agonists for the treatment of Parkinson's disease in Japan. DESIGN AND SETTING: We used a Markov model to simulate the course of Parkinson's disease and to compare the cost effectiveness of dopamine agonists added to levodopa with that of levodopa alone in Japan. The model assumed that 60-year-old men with Parkinson's disease in Hoehn-Yahr (HY) stages 2 to 5 using levodopa were administered dopamine agonists or continued on levodopa alone. The incremental cost effectiveness of dopamine agonists used for 10 years was then estimated. STUDY PERSPECTIVE: Societal. MAIN OUTCOME MEASURES AND RESULTS: In the patients in HY stage 2, the incremental cost effectiveness of dopamine agonists was 18,610,000 to 19,320,000 yen per quality-adjusted life-year (QALY) [$US 172,300 to $US 178,900/QALY; 1998 values] . In patients in HY stage 3 or higher, the use of dopamine agonists was dominant over levodopa alone mainly due to reduced cost for care. In sensitivity analyses, costs and effectiveness of dopamine agonists significantly influenced the results. The use of a generic formulation of bromocriptine was dominant over levodopa alone even in the patients with HY stage 2 disease. CONCLUSIONS: Dopamine agonists appear to be cost effective in advanced Parkinson's disease, although their use is sensitive to the costs and effectiveness of dopamine agonists. If factors discouraging the prescription of generic drugs in Japan were removed, the treatment of Parkinson's disease would become more cost effective.

Aged↗
PubMed2001

Ultimobranchial glands in the teleost (Plecoglossus altivelis ryukyuensis): special references to changes of gland volume with maturation.

In lower vertebrates, the bone-mineralizing hormone "calcitonin" is secreted from ultimobranchial glands, which assume various shapes, e.g., follicles, cellular masses, or cell strands. Histological observations support the view that in some teleosts, the glands increase in size when females maturate. We determined the exact volume of the gland in juveniles and adult males and females of a teleost, Ryukyuayu (Plecoglossus altivelis ryukyuensis). Furthermore, we examined plasma Ca, Na and K levels. In this species, the gland was fundamentally composed of a single follicle. The gland volume was converted to numerical data under a certain condition. It thus became clear that the value of the follicle wall was significantly increased only in maturing and mature females with high plasma Ca levels and that the value of the lumen did not show any statistically significant changes during growth and maturation.

Animals↗
PubMed2001

Cancer chemoprevention by ginseng in mouse liver and other organs.

Oral administration of red ginseng extracts (1% in diet for 40 weeks) resulted in the significant suppression of spontaneous liver tumor formation in C3H/He male mice. Average number of tumors per mouse in control group was 1.06, while that in red ginseng extracts-treated group was 0.33 (p<0.05). Incidence of liver tumor development was also lower in red ginseng extracts-treated group, although the difference from control group was not statistically significant. Anti-carcinogenic activity of white ginseng extracts, besides red ginseng extracts, was also investigated. In the present study, the administration of white ginseng extracts was proven to suppress tumor promoter-induced phenomena in vitro and in vivo. It is of interest that oral administration of the extracts of Ren-Shen-Yang- Rong-Tang, a white ginseng-containing Chinese medicinal prescription, resulted in the suppression of skin tumor promotion by 12-o-tetradecanoylphorbol-13-acetate in 7,12-dimethylbenz[a]anthracene-initiated CD-1 mice. These results suggest the usefulness of ginseng in the field of cancer prevention.

Animals↗
PubMed2001

Detection of p53 gene mutations in human esophageal squamous cell carcinomas using a p53 yeast functional assay: possible difference in esophageal carcinogenesis between the young and the elderly group.

A p53 yeast functional assay, which cannot only detect p53 gene mutations but also can assess p53 gene function, was used to screen for p53 gene dysfunction in human esophageal squamous cell carcinomas. Surgically resected frozen tissues of esophageal squamous cell carcinomas from 57 patients were examined for p53 gene mutation. Because the mean age of the patients diagnosed with esophageal squamous cell carcinoma was 64 years, we classified those who were <65 years of age as the Young Group and classified the others as the Elderly Group. The incidence of p53 gene mutations was 43 of 57 (75%). The incidence of p53 gene mutations observed in the Young Group was significantly higher than in the Elderly Group (P = 0.0007). Alcohol and smoking status did not relate to p53 gene mutation expression. Survival rate after surgery was not significantly associated with the presence of p53 gene mutation. However, in the Young Group with p53 gene mutation, those who had null mutations had a significantly shorter survival than those without null mutations (P = 0.0455). No other clinicopathological factors were associated with p53 gene mutations. Possibly, there may be a difference in esophageal carcinogenesis between the Young and the Elderly groups, because the incidence of p53 gene mutations is different between the two groups. In the Young Group, p53 gene mutation may cause esophageal carcinogenesis, and null mutation for p53 gene is a significant prognostic factor.

Age Factors↗
PubMed2001

[Intraoperative coating of tumor surface using fibrin glue as a prophylaxis for cancer cell detachment].

With the aim of preventing cancer cells from becoming detached and spreading into the abdominal cavity by operative procedures during surgical resection of cancer infiltrating into gastrointestinal serosa, the exposed area of the serosa in mice was coated with fibrin glue, a biological tissue adhesive, prior to resection. We then determined whether the coating could reduce the detachment and spread of cancer cells during the surgical procedure, and thus be capable of inhibiting the occurrence of peritonitis carcinomatosa. In vitro experiments demonstrated that the fibrin glue uniformly and strongly coated the exposed area of cancer, and furthermore, that the presence of fibrin glue coating significantly reduced the number of cancer cells which became detached. As a result of using this glue, the number of deaths due to peritonitis carcinomatosa among assay mice was significantly decreased. It is therefore considered that coating the exposed area of cancer with fibrin glue inhibits cancer cells from being detached and spread during an operation, and thus can be an effective means of preventing the recurrence of peritonitis.

Animals↗
PubMed2001

[Analysis of the action of dextran sulfate as a prophylaxis for peritoneal cancer metastasis, and its acting mechanism].

Although peritoneal cancer metastasis has the highest frequency of postoperative recurrence among digestive organ malignant tumors, there is no still decisive treatment. Dextran sulfate (DS) as a prophylaxis for cancer metastasis was examined with respect to its effect on cultured cells. DS was made to act on a strong adhesive neoplasm cell, and the action and acting mechanism were examined with respect to 1. readhesiveness, 2. cell cycle, and 3. gene analysis. The results suggest that: i) Once tumor cells are detached by DS, the free cells do not attach even when DS is removed, and ii) DS causes the cells to stop in the G1/G0 phase.

Animals↗
PubMed2001

[Usefulness of local administration of methotrexate bound to activated carbon particles (MTX-CH)].

We developed a new dosage formulation, methotrexate bound to activated carbon particles (MTX-CH), and used it to reduce tumors via its long-acting effect at the administration sites. MTX-CH was injected locally into tumors on the back of BALB/c mice, 30 mg/mouse, as MTX and compared with mice treated with MTX aqueous solution, saline solution, activated carbon particles (CH-40) and non-treated mice. The MTX concentration at the administration sites was higher in the MTX-CH group than in the MTX aqueous solution group. A marked effect on the control of tumor growth by MTX-CH was noted after repeated administration (every 3 days, total 4 times) throughout the observation period. Although tumor size was not reduced, necrosis was microscopically observed around the site of MTX-CH administration. For the reasons mentioned above, MTX-CH is superior to MTX aqueous solution in terms of long-acting effect at the administration sites and the control of tumor growth.

Animals↗
PubMed2001

Bilirubin as a tracer for detecting gastroesophageal reflux.

PURPOSE: The usefulness of intraesophageal monitoring of bilirubin, in diagnosing gastroesophageal reflux, was studied. PATIENTS AND METHODS: Bilirubin concentration and pH at 5 cm oral and anal to the esophagogastric junction were monitored for 24 hours in 19 patients with reflux esophagitis. The duration of bilirubin presented and pH less than 4.0 were obtained as the holding time (HT) of bilirubin and acid, respectively. RESULTS: There was no difference between HT of bilirubin and acid in the stomach and esophagus. In the stomach, HT of bilirubin did not correlate with acid. Whereas, in both of bilirubin and acid, HT in the esophagus correlated significantly with that in the stomach. The correlation was more definite for bilirubin than acid. CONCLUSIONS: Bilirubin and acid presented in the upper stomach for sufficient period independently. Bilirubin monitoring was useful to evaluate the etiology of damaging the esophageal mucosa and causes of symptoms by estimating duodenogastro-esophageal reflux, which has synergistic effect with acid.

Adult↗
PubMed2000

Dehydroaltenusin, a mammalian DNA polymerase alpha inhibitor.

Dehydroaltenusin was found to be an inhibitor of mammalian DNA polymerase alpha (pol alpha) in vitro. Surprisingly, among the polymerases and DNA metabolic enzymes tested, dehydroaltenusin inhibited only mammalian pol alpha. Dehydroaltenusin did not influence the activities of the other replicative DNA polymerases, such as delta and epsilon; it also showed no effect even on the pol alpha activity from another vertebrate (fish) or plant species. The inhibitory effect of dehydroaltenusin on mammalian pol alpha was dose-dependent, and 50% inhibition was observed at a concentration of 0.5 microm. Dehydroaltenusin-induced inhibition of mammalian pol alpha activity was competitive with the template-primer and non-competitive with the dNTP substrate. BIAcore analysis demonstrated that dehydroaltenusin bound to the core domain of the largest subunit, p180, of mouse pol alpha, which has catalytic activity, but did not bind to the smallest subunit or the DNA primase p46 of mouse pol alpha. These results suggest that the dehydroaltenusin molecule competes with the template-primer molecule on its binding site of the catalytic domain of mammalian pol alpha, binds to the site, and simultaneously disturbs dNTP substrate incorporation into the template-primer.

Animals↗
PubMed2000

In vitro expansion of mammalian telomere repeats by DNA polymerase alpha-primase.

Among the polymerases, DNA polymerase alpha-primase is involved in lagging strand DNA synthesis. A previous report indicated that DNA polymerase alpha-primase initiates primer RNA synthesis with purine bases on a single-stranded G-rich telomere repeat. In this study, we found that DNA polymerase alpha-primase precisely initiated with adenosine opposite the 3'-side thymidine in the G-rich telomere repeat 5'-(TTAGGG)(n)-3' under rATP-rich conditions. Then, DNA polymerase alpha-primase synthesized the nascent DNA fragments by extending the primer. It was remarkable that DNA polymerase alpha-primase further expanded the product DNA far beyond the length of the template DNA, as ladders of multiple hexanucleotides on polyacrylamide gel electrophoresis. Using an oligomer duplex 5'-A(GGGTTA)(5)-3'/5'-(TAACCC)(5)T-3' as a template-primer, we show that both the Klenow fragment of Escherichia coli DNA polymerase I and HIV reverse transcriptase could expand telomere DNA sequences as well, giving products greater than the size of the template DNA. The maximum product lengths with these polymerases were approximately 40-90 nt longer than the template length. Our data imply that DNA polymerases have an intrinsic activity to expand the hexanucleotide repeats of the telomere sequence by a slippage mechanism and that DNA polymerase alpha uses both the repeat DNA primers and the de novo RNA primers for expansion. On the other hand, a plasmid harboring a eukaryotic telomere repeat showed remarkable genetic instability in E.coli. The telomere repeats exhibited either expansions or deletions by multiple hexanucleotide repeats during culture for a number of generations, suggesting involvement of the slippage mechanism in the instability of telomeric DNA in vivo.

Animals↗
PubMed2000

Somatosensory cortex stimulation-evoked analgesia in rats: potentiation by NO synthase inhibition.

Clinical and immunohistochemical evidence suggests the possible significance of electrical stimulation of the secondary somatosensory cortex (S-II) as an analgesic therapy. The aim of the present study was to gain behavioral evidence for S-II stimulation-induced antinociception in conscious rats and to evaluate if the evoked antinociception can be potentiated by the neuronal NO synthase inhibitor 7-nitro-indazole. S-II stimulation produced a weak antinociception in the formalin-induced nociception test, but not in the thermal or mechanical nociception tests. This effect was remarkably potentiated by systemic administration of 7-nitro-indazole at a small dose that had no effect by itself. Thus, our data provide behavioral evidence for S-II stimulation-induced analgesia and may also predict a novel therapeutic strategy in combination with NO synthase inhibitors.

Analgesia↗
PubMed2000

Serum-soluble fas level determines clinical symptoms and outcome of patients with aggressive non-Hodgkin's lymphoma.

Soluble Fas (sFas) blocks apoptosis induced by Fas ligand in vitro. The serum concentration of sFas is elevated in lympho-proliferative diseases. We hypothesized that higher levels of sFas worsen the clinical symptoms and outcome of patients with aggressive non-Hodgkin's lymphoma (NHL). We prospectively measured the serum concentrations of sFas in 67 consecutive patients with aggressive NHL (59 with diffuse large cell lymphoma and 8 with diffuse small cleaved cell lymphoma). sFas was significantly elevated in patients with aggressive NHL compared to healthy controls (N = 36, P< 0.005), while sFas in patients with B symptoms (4.20 +/- 2.12 microg/l) was significantly higher than in those without B symptoms (2.66 +/- 1.08 microg/l, P < 0.005). No significant difference was observed between B-cell lymphoma and T-cell lymphoma or between patients with clinical stage I or II and those with clinical stage III or IV. Significant correlations were found between sFas concentration and both soluble interleukin-2 receptor (R = 0.400, P < 0.001) and C-reactive protein (R = 0.340, P < 0.01) levels in patients with aggressive NHL. No correlation was observed between sFas and either white blood cell count or lactate dehydrogenase. Generalized Wilcoxon analysis revealed that NHL patients with sFas less than 4 microg/l had better overall survival than those with sFas above 4 microg/l (P < 0.001). The serum concentration of sFas might be associated with clinical symptoms and the prognosis of patients with aggressive NHL.

Adolescent↗
PubMed2000

Chylothorax after thoracoscopic esophagectomy.

Among 30 patients who underwent thoracoscopic esophagectomy with lymphadenectomy for thoracic esophageal cancer, from July 1995 to May 1997, chylothorax developed in 2 patients (7%). In Case 1, the ligation of the thoracic duct under conventional right thoracotomy was performed on the 9th day after esophagectomy. After ligation, the pleural effusion was decreased, and the patient was discharged from hospital on the 25th day after the second operation. In Case 2, massive pleural effusion developed on the 10th day after esophagectomy (at 3 days after thoracic drainage tube was removed). The thoracic duct was ligated at the level just cranial to the diaphragm thoracoscopically on the 14th day after esophagectomy. The patient was discharged from hospital on the 30th day after the second operation. Injury to the thoracic duct due to a magnification effect of the view of scopic surgery remains a pitfall in thoracoscopic esophagectomy. But thoracoscopic ligation of thoracic duct was effective and safe for these two cases of chylothorax after esophagectomy.

Chylothorax↗