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1.
Gut ; 55(3): 415-24, 2006 Mar.
Article in English | MEDLINE | ID: mdl-16174657

ABSTRACT

BACKGROUND: While tumour necrosis factor alpha (TNF-alpha) appears to be associated with the development of non-alcoholic steatohepatitis (NASH), its precise role in the pathogenesis of NASH is not well understood. METHODS: Male mice deficient in both TNF receptors 1 (TNFR1) and 2 (TNFR2) (TNFRDKO mice) and wild-type mice were fed a methionine and choline deficient (MCD) diet or a control diet for eight weeks, maintaining isoenergetic intake. RESULTS: MCD dietary feeding of TNFRDKO mice for eight weeks resulted in attenuated liver steatosis and fibrosis compared with control wild-type mice. In the liver, the number of activated hepatic Kupffer cells recruited was significantly decreased in TNFRDKO mice after MCD dietary feeding. In addition, hepatic induction of TNF-alpha, vascular cell adhesion molecule 1, and intracellular adhesion molecule 1 was significantly suppressed in TNFRDKO mice. While in control animals MCD dietary feeding dramatically increased mRNA expression of tissue inhibitor of metalloproteinase 1 (TIMP-1) in both whole liver and hepatic stellate cells, concomitant with enhanced activation of hepatic stellate cells, both factors were significantly lower in TNFRDKO mice. In primary cultures, TNF-alpha administration enhanced TIMP-1 mRNA expression in activated hepatic stellate cells and suppressed apoptotic induction in activated hepatic stellate cells. Inhibition of TNF induced TIMP-1 upregulation by TIMP-1 specific siRNA reversed the apoptotic suppression seen in hepatic stellate cells. CONCLUSIONS: Enhancement of the TNF-alpha/TNFR mediated signalling pathway via activation of Kupffer cells in an autocrine or paracrine manner may be critically involved in the pathogenesis of liver fibrosis in this NASH animal model.


Subject(s)
Fatty Liver/complications , Kupffer Cells/metabolism , Liver Cirrhosis, Experimental/etiology , Tumor Necrosis Factor-alpha/physiology , Animals , Apoptosis , Cell Adhesion Molecules/biosynthesis , Choline Deficiency/complications , Fatty Liver/metabolism , Fatty Liver/pathology , Gene Expression Regulation , Liver Cirrhosis, Experimental/metabolism , Liver Cirrhosis, Experimental/pathology , Male , Methionine/deficiency , Mice , Mice, Knockout , Mitochondria, Liver/physiology , Mutation , RNA, Messenger/genetics , Receptors, Tumor Necrosis Factor, Type I/deficiency , Receptors, Tumor Necrosis Factor, Type I/genetics , Receptors, Tumor Necrosis Factor, Type I/physiology , Receptors, Tumor Necrosis Factor, Type II/deficiency , Receptors, Tumor Necrosis Factor, Type II/genetics , Receptors, Tumor Necrosis Factor, Type II/physiology , Reverse Transcriptase Polymerase Chain Reaction/methods , Signal Transduction , Tissue Inhibitor of Metalloproteinase-1/biosynthesis , Tissue Inhibitor of Metalloproteinase-1/genetics , Tumor Necrosis Factor-alpha/biosynthesis
2.
J Cell Sci ; 114(Pt 18): 3397-406, 2001 Sep.
Article in English | MEDLINE | ID: mdl-11591827

ABSTRACT

Checkpoint controls ensure chromosomal integrity through the cell cycle. Chk1 and Cds1/Chk2 are effector kinases in the G(2)-phase checkpoint activated by damaged or unreplicated DNA, and they prevent entry into M-phase through inhibition of cyclin B-Cdc2 kinase activation. However, little is known about how the effector kinases are regulated when the checkpoint is attenuated. Recent studies indicate that Chk1 is also involved in the physiological G(2)-phase arrest of immature Xenopus oocytes via direct phosphorylation and inhibition of Cdc25C, the activator of cyclin B-Cdc2 kinase. Bearing in mind the overlapping functions of Chk1 and Cds1, here we have studied the involvement of Xenopus Cds1 (XCds1) in the G(2)/M-phase transition of immature oocytes and the regulation of its activity during this period. Protein levels of XCds1 remained constant throughout oocyte maturation and early embryonic development. The levels of XCds1 kinase activity were high in immature oocytes and decreased at the meiotic G(2)/M-phase transition. Consistently, when overexpressed in immature oocytes, wild-type, but not kinase-deficient, XCds1 significantly delayed entry into M-phase after progesterone treatment. The inactivation of XCds1 depended on the activation of cyclin B-Cdc2 kinase, but not MAP kinase. Although XCds1 was not directly inactivated by cyclin B-Cdc2 kinase in vitro, XCds1 was inactivated by overexpression of cyclin B, which induces the activation of cyclin B-Cdc2 kinase without progesterone. Thus, the present study is the first indication of Cds1 activity in cells that are physiologically arrested at G(2)-phase, and of its downregulation at entry into M-phase.


Subject(s)
CDC2 Protein Kinase/metabolism , CDC28 Protein Kinase, S cerevisiae/metabolism , G2 Phase/physiology , Mitosis/physiology , Oocytes/cytology , Protein Kinases/metabolism , Protein Serine-Threonine Kinases , Animals , Cell Nucleus/chemistry , Checkpoint Kinase 2 , Down-Regulation , Female , G2 Phase/drug effects , Meiosis/physiology , Mitosis/drug effects , Oocytes/enzymology , Progesterone/pharmacology , Protein Kinase Inhibitors , Protein Kinases/chemistry , Xenopus
3.
Gene ; 277(1-2): 101-10, 2001 Oct 17.
Article in English | MEDLINE | ID: mdl-11602347

ABSTRACT

The Xenopus telomerase catalytic component gene, xTERT (Xenopus telomerase reverse transcriptase), has been cloned. The production of xTERT recombinant protein together with the proposed Xenopus telomerase RNA (xTR) (Chen et al., 2000. Cell 100, 503-514) in a rabbit reticulocyte lysate system led to the reconstitution of active telomerase, indicating that both products are functional telomerase components. Both xTERT expression and telomerase activity are high from the early to the late blastula stage. However, they are decreased at the gastrula stage and thereafter, suggesting that the xTERT expression level is the primary mechanism for regulating telomerase activity in Xenopus development. This is the first report of a non-mammalian vertebrate TERT gene. Sequence comparison of xTERT with human and mouse TERTs has uncovered four regions conserved in the amino-terminal halves of vertebrate TERT proteins, the functions of which will be discussed herein.


Subject(s)
Telomerase/genetics , Xenopus laevis/genetics , Amino Acid Sequence , Animals , Catalytic Domain , Cell Line , DNA, Complementary/chemistry , DNA, Complementary/genetics , DNA, Complementary/isolation & purification , DNA-Binding Proteins , Embryo, Nonmammalian/metabolism , Embryonic Development , Gene Expression Regulation, Developmental , Gene Expression Regulation, Enzymologic , Humans , Molecular Sequence Data , RNA/genetics , RNA/metabolism , Sequence Alignment , Sequence Analysis, DNA , Sequence Homology, Amino Acid , Xenopus laevis/embryology
4.
Biosci Biotechnol Biochem ; 65(5): 1175-80, 2001 May.
Article in English | MEDLINE | ID: mdl-11440134

ABSTRACT

Carboxypeptidase Y (CPY) has been used as a maker enzyme for investigations on intracellular transport of vacuolar proteins and on vacuolar biogenesis in Saccharomyces cerevisiae. We describe the cloning and characterization of the CPY homologue encoding gene (cpyA) from the filamentous fungus Aspergillus nidulans. The cpyA gene has one intron and encodes a protein with 552 amino acids containing a putative signal sequence and pro-sequence. The predicted CpyA protein is highly similar in sequence with carboxypeptidases from several yeast species and contains a catalytic triad (Asp-His-Ser) like that of serine carboxypeptidase. The cpyA disruptant cells showed reduced levels of intracellular carboxypeptidase. These results suggest that the cpyA gene encodes a vacuolar carboxypeptidase in A. nidulans.


Subject(s)
Aspergillus nidulans/genetics , Carboxypeptidases/genetics , Genes, Fungal , Amino Acid Sequence , Aspergillus nidulans/enzymology , Base Sequence , Carboxypeptidases/metabolism , Chromosomes, Fungal , Cloning, Molecular , DNA, Complementary , Molecular Sequence Data , Sequence Homology, Amino Acid
5.
Mol Microbiol ; 40(4): 835-45, 2001 May.
Article in English | MEDLINE | ID: mdl-11401691

ABSTRACT

MukF, MukE and MukB proteins form a complex that may participate in the organization of folded sister chromosomes in Escherichia coli. We have found that a MukB-GFPuv4 fusion protein is observed as discrete fluorescent foci, which are localized within cellular spaces occupied by nucleoids, but not at the constriction site of cell division in living cells. In contrast, MukB-GFPuv4 is distributed throughout the whole cell when either MukF or MukE is absent. Statistical analysis revealed that most newborn cells have two foci of mukB-gfpUV4 at one-quarter and three-quarter positions in the cell length and one focus of SeqA-bound nascent DNA at or near the middle of the cell. Subsequently, the single SeqA focus divides into two foci, and then these migrate to the one-quarter and three-quarter positions. Before cell division, most long cells have two SeqA foci and four MukB-GFPuv4 foci. In early stationary phase, SeqA foci disappear, but one or two foci of MukB-GFPuv4 remain. We discuss the reorganization and proper arrangement of folded sister chromosome in the cell quarter positions, which are performed after release from the long-time cohesion of sister chromosomes.


Subject(s)
Bacterial Proteins/genetics , Bacterial Proteins/metabolism , Chromosomal Proteins, Non-Histone , DNA, Bacterial/metabolism , Escherichia coli Proteins , Escherichia coli/genetics , Repressor Proteins , Transcription Factors , Bacterial Outer Membrane Proteins , Cell Division , Chromosomes, Bacterial , Culture Media , DNA-Binding Proteins , Data Interpretation, Statistical , Escherichia coli/growth & development , Escherichia coli/metabolism , Fluorescent Antibody Technique, Indirect , Green Fluorescent Proteins , Luminescent Proteins/genetics , Luminescent Proteins/metabolism , Microscopy, Fluorescence , Mutation , Operon , Recombinant Fusion Proteins/genetics , Recombinant Fusion Proteins/metabolism
6.
Oncol Rep ; 8(4): 815-9, 2001.
Article in English | MEDLINE | ID: mdl-11410790

ABSTRACT

Resistance to chemotherapeutic agents is a major problem for successful cancer treatment. P-glycoprotein (Pgp), a product of the multidrug resistance (MDR)1 gene expressed in cancer cells, is one of the mechanism of MDR. However, there are few reports regarding the effects of Pgp on prognosis of colorectal cancer (CRC) after surgery. We examined a total of 80 patients (45 males and 35 females with an average age of 69 years) whose CRCs were classified into stage 2-4 and completely resected surgically in our institute between January 1990 and September 1999. To evaluate Pgp expression in CRC, immunohistochemical stain was performed with a monoclonal antibody. Relationships between Pgp expression and clinicopathological variables which may have affected prognosis were evaluated. Survival curves were calculated using the Kaplan-Meier method, and differences were evaluated with the log-rank test. The Cox's proportional hazards model was used in the univariate and multivariate survival analysis. Pgp expression showed a significant correlation with histological differentiation (p=0.023). However, no correlation was observed with gender, tumor location, lymph node metastasis, lymphatic invasion, venous invasion, and cancer stages. Survival rates after surgery tended (p=0.093) to be higher in Pgp (+) than Pgp (-) patients. Pgp was not a significant prognostic factor by univariate analysis and multivariate analysis adjusted for other clinicopathologic variables. Survival rates after surgery tended to be higher in Pgp (+) than Pgp (-) patients and Pgp expression was correlated with histological differentiation of CRC. Thus, a relative resistance of CRC to conventional chemotherapy may be partly caused by Pgp expressed in well or moderately differentiated CRC. However, Pgp expression was not a significant independent prognostic factor in advanced CRC after surgery.


Subject(s)
ATP Binding Cassette Transporter, Subfamily B, Member 1/metabolism , Colorectal Neoplasms/diagnosis , Colorectal Neoplasms/metabolism , Clinical Trials as Topic , Colorectal Neoplasms/mortality , Colorectal Neoplasms/surgery , Drug Resistance, Multiple , Drug Resistance, Neoplasm , Gene Expression , Humans , Immunoenzyme Techniques , Lymphatic Metastasis , Neoplasm Invasiveness , Prognosis , Proportional Hazards Models , Survival Rate
7.
Gene ; 268(1-2): 23-30, 2001 May 02.
Article in English | MEDLINE | ID: mdl-11368897

ABSTRACT

In Saccharomyces cerevisiae, vacuoles play very important roles in pH and osmotic regulation, protein degradation and storage of amino acids, small ions as well as polyphosphates. In filamentous fungi, however, little is known about vacuolar functions at a molecular level. In this paper, we report the isolation of the vpsA gene from the filamentous fungus Aspergillus nidulans as a homologue of the VPS1 gene of S. cerevisiae which encodes a dynamin-related protein. The vpsA gene encodes a polypeptide consisting of 696 amino acids that is nearly 60% homologous to the S. cerevisiae Vps1. Similar to Vps1, VpsA contains a highly conserved tripartite GTPase domain but lacks the pleckstrin homology domain and proline-rich region. The vpsA disruptant shows poor growth and contains highly fragmented vacuoles. These results suggest that A. nidulans VpsA functions in the vacuolar biogenesis.


Subject(s)
Aspergillus nidulans/genetics , Fungal Proteins/genetics , GTP Phosphohydrolases/genetics , GTP-Binding Proteins , Vacuoles/metabolism , Amino Acid Sequence , Aspergillus nidulans/growth & development , Aspergillus nidulans/metabolism , Bacterial Proteins , Base Sequence , Binding Sites , Carrier Proteins/genetics , Carrier Proteins/metabolism , Cell Division/genetics , Cloning, Molecular , Dynamins , Fungal Proteins/metabolism , GTP Phosphohydrolases/metabolism , Genetic Complementation Test , Guanosine Triphosphate/metabolism , Molecular Sequence Data , Mutation , Sequence Homology, Amino Acid , Vacuoles/genetics , Vacuoles/pathology , Vesicular Transport Proteins
8.
Hepatogastroenterology ; 48(37): 128-32, 2001.
Article in English | MEDLINE | ID: mdl-11268947

ABSTRACT

BACKGROUND/AIMS: The present study compared the effects of sequential methotrexate and 5-fluorouracil followed by leucovorin rescue (MFL), as an adjuvant chemotherapy versus a combination of UFT and mitomycin C (MMC), on patient survival and recurrence after surgery for colorectal carcinoma. METHODOLOGY: Between January 1990 and December 1997, a total of 55 patients with advanced colorectal cancer were treated postsurgically by adjuvant chemotherapy using MFL or UFT-MMC. Surgical treatment was performed according to standardized procedures for radical resection of colorectal cancer. The patients were divided into 2 groups after surgery. The MFL regimen consisted of MTX (100 mg/m2) and 5-FU (600 mg/m2) at hour 24, followed by leucovorin rescue. The UFT-MMC regimen consisted of MMC (12 mg/m2) intraoperatively and MMC (6 mg/m2) every other week after surgery for 2 months, and oral UFT (375 mg/m2/day), a combination of tegafur and uracil in a molar ratio of 1:4, was continued for 3 years or longer depending on the patients tolerance. RESULTS: The overall survival rates after surgery were significantly (P < 0.05) higher in the MFL than the UFT-MMC group. Recurrence rates were significantly lower in the MFL than the UFT-MMC group, especially for liver recurrence. Disease-free survival was significantly (P < 0.05) higher in the MFL than the UFT-MMC group. CONCLUSIONS: These results demonstrated the superiority of MFL therapy for improving postsurgical survival in patients with advanced colorectal cancer, in particular those patients with a high risk of recurrence following potential curative resection.


Subject(s)
Antineoplastic Combined Chemotherapy Protocols/administration & dosage , Carcinoma/drug therapy , Colorectal Neoplasms/drug therapy , Aged , Ambulatory Care , Antineoplastic Combined Chemotherapy Protocols/adverse effects , Carcinoma/mortality , Carcinoma/surgery , Chemotherapy, Adjuvant , Colorectal Neoplasms/mortality , Colorectal Neoplasms/surgery , Combined Modality Therapy , Drug Administration Schedule , Female , Fluorouracil/administration & dosage , Humans , Leucovorin/administration & dosage , Male , Methotrexate/administration & dosage , Mitomycin/administration & dosage , Survival Rate , Tegafur/administration & dosage , Uracil/administration & dosage
9.
Proc Natl Acad Sci U S A ; 98(1): 125-9, 2001 Jan 02.
Article in English | MEDLINE | ID: mdl-11134534

ABSTRACT

The role of PKN, a fatty acid- and Rho small GTPase-activated protein kinase, in cell-cycle regulation was analyzed. Microinjection of the active form of PKN into a Xenopus embryo caused cleavage arrest, whereas normal cell division proceeded in the control embryo microinjected with buffer or the inactive form of PKN. Exogenous addition of the active form of PKN delayed mitotic timing in Xenopus egg cycling extracts judging by morphology of sperm nuclei and Cdc2/cyclin B histone H1 kinase activity. The kinase-negative form of PKN did not affect the timing, suggesting that delayed mitotic timing depends on the kinase activity of PKN. The dephosphorylation of Tyr-15 of Cdc2 was also delayed in correlation with Cdc2/cyclin B histone H1 kinase activation in extracts containing active PKN. The Cdc25C activity for the dephosphorylation of Tyr-15 in Cdc2 was suppressed by pretreatment with the active form of PKN. Furthermore, PKN efficiently phosphorylated Cdc25C in vitro, indicating that PKN directly inhibits Cdc25C activity by phosphorylation. These results suggest that PKN plays a significant role in the control of mitotic timing by inhibition of Cdc25C.


Subject(s)
Cell Cycle Proteins , Mitosis/drug effects , Nuclear Proteins , Protein Serine-Threonine Kinases/pharmacology , Protein-Tyrosine Kinases/pharmacology , ras-GRF1/antagonists & inhibitors , Animals , CDC2 Protein Kinase/metabolism , Cell Extracts , Cell Nucleus/metabolism , Cyclin B/metabolism , Enzyme Activation/drug effects , Female , Male , Microinjections , Oocytes/cytology , Oocytes/enzymology , Oocytes/metabolism , Phosphorylation/drug effects , Protein Kinases/metabolism , Protein Serine-Threonine Kinases/metabolism , Protein Tyrosine Phosphatases/metabolism , Protein-Tyrosine Kinases/metabolism , Recombinant Fusion Proteins , Spermatozoa/cytology , Xenopus/embryology , Xenopus/metabolism , Xenopus Proteins , ras-GRF1/metabolism
10.
Curr Surg ; 58(5): 493-4, 2001.
Article in English | MEDLINE | ID: mdl-16093073

ABSTRACT

PURPOSE: Tension-free hernia repair with polypropylene mesh plug and patch is currently the most popular technique for open inguinal hernioplasty. It is well tolerated by most patients with few complications. Despite these excellent results, late-onset complications may occur. METHODS: An 83-year-old man reported 2 weeks of bloody stool. His medical history was significant for a left open inguinal herniorrhaphy with the mesh plug and patch technique. Barium enema revealed a stenotic segment in the sigmoid colon and multiple diverticulosis. Because a malignant lesion could not be ruled out, the patient underwent an operation. Laparotomy revealed an inflamed sigmoid colon with diverticulosis adherent to a hard tumor, which was mesh plug used for the previous open inguinal hernia repair. After mobilization of the adhesion between the mesh plug tumor and the sigmoid colon, sigmoidectomy was performed. The patient's postoperative course was uneventful. CONCLUSIONS: We reported a case of sigmoid colon diverticulosis adherent to mesh plug migration after open inguinal hernia repair. The potential risk of plug migration should be well understood by the surgeon. To avoid this risk completely, several methods have been proposed such as suturing the plug and patch together, or using an all-in-one design such as the Prolene Hernia System (Johnson and Johnson Co., Tokyo, Japan).

11.
J Surg Oncol ; 75(1): 31-6, 2000 Sep.
Article in English | MEDLINE | ID: mdl-11025459

ABSTRACT

BACKGROUND AND OBJECTIVES: The present study compared the effects of sequential methotrexate and fluorouracil followed by leucovorin rescue (MFL), as an adjuvant chemotherapy vs. UFT (a combination of uracil and tegafur), on patient survival and recurrence following surgery for advanced gastric carcinoma. METHODS: Between July 1990 and June 1998, a total of 54 patients with advanced gastric cancer were treated postoperatively by adjuvant chemotherapy using MFL or UFT. Surgical treatment was performed according to standardized procedures for radical resection of gastric cancer. The patients were stratified into two groups following surgery. The MFL regimen consisted of methotrexate (100 mg/m2) and 5-fluorouracil (600 mg/m2) at hour 3, followed by leucovorin rescue. The oral UFT (375 mg/m2/day), a combination of tegafur and uracil in a molar ratio of 1:4, was continued for 3 years or longer depending on the patients tolerance. RESULTS: In stage 3 gastric cancer, the overall survival rates following surgery was significantly (p < 0.05) higher in the MFL than the UFT group. Difference in disease free survival was not statistically significant between the groups. Recurrence rates showed a trend (p = 0.08) to decrease in the MFL than the UFT group. In stage 4 gastric cancer, no significant difference was obtained in the overall survival rates between the groups. CONCLUSIONS: The present results suggested the superiority of MFL treatment for improving postoperative survival in patients with advanced gastric cancer, in particular for those patients with a high risk of recurrence following potential curative resection. In patients with stage 4 gastric cancer, however, MFL treatment showed similar effects as UFT on the postsurgical survival of the patients.


Subject(s)
Antineoplastic Combined Chemotherapy Protocols/therapeutic use , Stomach Neoplasms/drug therapy , Aged , Antineoplastic Combined Chemotherapy Protocols/administration & dosage , Chemotherapy, Adjuvant , Drug Administration Schedule , Female , Fluorouracil/administration & dosage , Gastrectomy/mortality , Humans , Leucovorin/administration & dosage , Lymphatic Metastasis , Male , Methotrexate/administration & dosage , Middle Aged , Neoplasm Invasiveness , Neoplasm Staging , Stomach Neoplasms/mortality , Stomach Neoplasms/pathology , Survival Rate , Tegafur/administration & dosage , Uracil/administration & dosage
12.
J Clin Gastroenterol ; 31(3): 217-21, 2000 Oct.
Article in English | MEDLINE | ID: mdl-11034000

ABSTRACT

Helicobacter pylori infection may play a role in the development of gastric cancer; however, a quantitative evaluation of the density of H. pylori infection has not been reported previously in relation to the histologic stage and type of cancer. This study was designed to compare the density of H. pylori infection to the histologic stage and type of gastric cancer. Between March 1996 and March 1998, surgical resection of primary lesion was performed in 50 patients with gastric cancer (39 men and 11 women with a mean age of 67 years) at our institution. Using immunohistochemical stains, the density of H. pylori infection was evaluated semiquantitatively at cancer site as well as noncancerous mucosa adjacent to cancer. This density was compared with the histologic stage and the type of gastric cancer. The severity of the mucosal atrophy was evaluated using the updated Sydney System. The prevalences and density of H. pylori infection decreased in proportion to advances in the cancer stage and the mucosal atrophy. In early cancer of the intestinal- and diffuse-type, the prevalence of H. pylori in adjacent sites was almost 90% and was significantly higher (p < 0.01) than that seen in the advanced cancer lesions. In the intestinal-type early cancer, the prevalence and density of infection was higher (p < 0.05) in the adjacent mucosa than in the cancer site, whereas in the diffuse-type early cancer, H. pylori was found in all cases at the cancer site and the adjacent site. In advanced cancer, the prevalence of H. pylori was about 40% in the adjacent site and about 10% in the cancer site in both histologic types. These figures were significantly lower (p < 0.01) than in the early cancers. The prevalence and density of infection did not differ in the intestinal- and diffuse-type gastric cancers, but did decrease with more advanced cancer stages. The changes in local environment of the advanced cancer may not be conducive to the survival of H. pylori. Thus, the prevalence of H. pylori may be affected by the histologic stage rather than the histologic type of gastric cancer, and the organism may play a similar role, but through different pathways, in the pathogenesis of both types of cancer.


Subject(s)
Helicobacter Infections/complications , Helicobacter pylori , Stomach Neoplasms/microbiology , Aged , Female , Gastric Mucosa/microbiology , Gastric Mucosa/pathology , Helicobacter Infections/epidemiology , Humans , Male , Neoplasm Staging , Prevalence , Stomach Neoplasms/pathology
13.
Genes Dev ; 14(18): 2344-57, 2000 Sep 15.
Article in English | MEDLINE | ID: mdl-10995390

ABSTRACT

Inactivation of cyclin B-Cdc2 kinase at the exit from M phase depends on the specific proteolysis of the cyclin B subunit, whereas the Cdc2 subunit remains present at nearly constant levels throughout the cell cycle. It is unknown how Cdc2 escapes degradation when cyclin B is destroyed. In Xenopus egg extracts that reproduce the exit from M phase in vitro, we have found that dissociation of the cyclin B-Cdc2 complex occurred under conditions where cyclin B was tethered to the 26S proteasome but not yet degraded. The dephosphorylation of Thr 161 on Cdc2 was unlikely to be necessary for the dissociation of the two subunits. However, the dissociation was dependent on the presence of a functional destruction box in cyclin B. Cyclin B ubiquitination was also, by itself, not sufficient for separation of Cdc2 and cyclin B. The 26S proteasome, but not the 20S proteasome, was capable of dissociating the two subunits. These results indicate that the cyclin B and Cdc2 subunits are separated by the proteasome through a mechanism that precedes proteolysis of cyclin B and is independent of proteolysis. As a result, cyclin B levels decrease on exit from M phase but Cdc2 levels remain constant.


Subject(s)
CDC2 Protein Kinase/metabolism , Cyclin B/metabolism , Cysteine Endopeptidases/metabolism , Mitosis , Multienzyme Complexes/metabolism , Animals , In Vitro Techniques , Ovum/growth & development , Ovum/metabolism , Peptide Hydrolases/metabolism , Precipitin Tests , Protamine Kinase/metabolism , Proteasome Endopeptidase Complex , Ubiquitins/metabolism , Xenopus
14.
EMBO J ; 19(17): 4513-23, 2000 Sep 01.
Article in English | MEDLINE | ID: mdl-10970845

ABSTRACT

To investigate the regulatory mechanisms of the cell cycle transition from M phase to M phase in meiotic cycles, a Xenopus oocyte extract that performs the M-M transition has been developed. Using the meiotic extract, we found that a low level of Cdc2 activity remained at the exit of meiosis I (MI), due to incomplete degradation of cyclin B. The inactivation of the residual Cdc2 activity induced both entry into S phase and tyrosine phosphorylation on Cdc2 after MI. Quantitative analysis demonstrated that a considerable amount of Wee1 was present at the MI exit and Cdc2 inhibitory phosphorylation during this period was suppressed by the dominance of Cdc2 over Wee1. Consistently, the addition of more than a critical amount of Wee1 to the extract induced Cdc2 inhibitory phosphorylation, changing the M-M transition into an M-S-M transition. Thus, the Cdc2 activity remaining at MI exit is required for suppressing entry into S phase during the meiotic M-M transition period.


Subject(s)
CDC2 Protein Kinase/metabolism , Cell Cycle Proteins , Meiosis , Nuclear Proteins , Oocytes/cytology , Animals , Cell Extracts , Metaphase , Oocytes/enzymology , Protein-Tyrosine Kinases/antagonists & inhibitors , Recombinant Proteins/antagonists & inhibitors , Xenopus , Xenopus Proteins
15.
J Gastroenterol Hepatol ; 15(6): 617-21, 2000 Jun.
Article in English | MEDLINE | ID: mdl-10921414

ABSTRACT

BACKGROUND: The rapid urease test and touch cytology have been used for the rapid detection of Helicobacter pylori infection. Recently, a modified rapid urease (MRU) test, which provides results in 20 min has been available on a commercial basis. To date, few reports have evaluated the accuracy of this test. This study evaluated the sensitivity, specificity, and accuracy of the MRU test and touch cytology to detect H. pylori in relation to the density of H. pylori infection determined semi-quantitatively by using immunohistochemical stains. METHODS: Biopsy specimens obtained from a total of 60 patients who underwent endoscopy for evaluation of gastroduodenal diseases were studied by using the MRU test, Giemsa stain for touch smear tissue and histological methods. An immunohistochemical stain was used as a standard, and the density of H. pylori infection was graded according to the number of individual bacteria seen as follows: grade 0 = 0; grade 1+ = 1-9; grade 2+ = 10-29; grade 3+ = 30-99; grade 4+ > or = 100. The severity of gastritis was evaluated histologically in each specimen and compared with the density of H. pylori infection. RESULTS: The MRU test had an overall sensitivity of 73%, specificity of 100% and accuracy of 85%. The Giemsa stain had a sensitivity of 91%, specificity of 100% and accuracy of 95%.The sensitivities of the MRU test and Giemsa stain decreased in mild H. pylori infection. In the MRU test, the sensitivity was 47% when the density of H. pylori infection was 1+, while 80-100% sensitivities were obtained when the densities of infection were > or = 2+. With the Giemsa stain, the sensitivity was 80% when the density was 1+, while the sensitivity increased to 100% when the densities were > or = 2+. The severity of gastritis determined by the Rauws scores showed a positive correlation with the density of H. pylori infection as evaluated by immunohistochemical staining. CONCLUSIONS: The MRU test had high sensitivity and specificity for moderate to severe H. pylori infection, but it may result in false-negative results in tests for mild infection. As the MRU test has the advantages of shorter incubation times and low cost, a combination of the MRU test and the Giemsa stain for touch cytology may be the most time- and cost-efficient tests in a clinical setting for the diagnosis of H. pylori infection.


Subject(s)
Gastritis/microbiology , Helicobacter Infections/diagnosis , Helicobacter pylori/isolation & purification , Immunohistochemistry , Urease/analysis , Cytodiagnosis , Female , Gastric Mucosa/pathology , Gastritis/pathology , Helicobacter Infections/pathology , Helicobacter pylori/enzymology , Humans , Male , Middle Aged , Sensitivity and Specificity
16.
EMBO J ; 19(15): 4144-53, 2000 Aug 01.
Article in English | MEDLINE | ID: mdl-10921894

ABSTRACT

The 26S proteasome is a multisubunit protein- destroying machinery that degrades ubiquitin-tagged proteins. To date only a single species of Rpn10, which possibly functions as a multiubiquitin chain-binding subunit, has been identified in various organisms. Here we report that mouse Rpn10 mRNAs occur in at least five distinct forms, named Rpn10a to Rpn10e, and that they are generated from a single gene by developmentally regulated, alternative splicing. Rpn10a is ubiquitously expressed, whereas Rpn10e is expressed only in embryos, with the highest levels of expression in the brain. Both forms of Rpn10 are components of the 26S proteasome, with an apparently similar affinity for multiubiquitylated [(125)I]lysozyme in vitro. However, they exert markedly divergent effects on the destruction of B-type cyclin in Xenopus egg extracts. Thus, the 26S proteasome occurs in at least two functionally distinct forms: one containing a ubiquitously expressed Rpn10a and the other a newly identified, embryo-specific Rpn10e. While the former is thought to perform proteolysis constitutively in a wide variety of cells, the latter may play a specialized role in early embryonic development.


Subject(s)
Alternative Splicing , Carrier Proteins/genetics , Gene Expression Regulation, Developmental , Peptide Hydrolases/genetics , Proteasome Endopeptidase Complex , Amino Acid Sequence , Animals , Conserved Sequence , Cyclin B/metabolism , Evolution, Molecular , Mice , Molecular Sequence Data , RNA-Binding Proteins , Sequence Homology, Amino Acid , Ubiquitins/metabolism
17.
Int J Angiol ; 9(1): 20-22, 2000 Jan.
Article in English | MEDLINE | ID: mdl-10629319

ABSTRACT

To evaluate the appropriate use of the pararectal retroperitoneal approach (RPA) in abdominal aortic aneurysm (AAA) repair, we retrospectively compared the RPA with the transperitoneal approach (TPA). Fifty-four patients in whom the RPA was used and 92 who had the TPA were included in the study. The mean operating time was 286 minutes with the RPA and 252 minutes with the TPA. Intraoperative blood transfusions were necessary in 9.3% of patients who had the RPA and 16.2% who had the TPA. As assessed by computerized tomographic scanning, the mean size of the postoperative retroperitoneal hematoma was 440 mL in the RPA group and 180 mL in the TPA group. Ileus resolved a mean of 3 days postoperatively in the RPA group and 5 days postoperatively in the TPA group. The mean length of postoperative hospitalization was 21 days in the RPA group and 23 days in the TPA group. Prolonged postoperative ileus occurred in no patients in the RPA group and in three patients in the TPA group. None of the differences in outcomes between the groups were significant. Our findings indicate that, in carefully selected patients, the pararectal RPA is suitable for AAA repair.

18.
Jpn J Cancer Res ; 90(9): 1016-25, 1999 Sep.
Article in English | MEDLINE | ID: mdl-10551333

ABSTRACT

AC-7700, a novel combretastatin A-4 derivative, suppresses the growth of solid tumors by inhibiting tumor perfusion. We evaluated the antitumor activity of AC-7700 on solid tumors in two experimental models, an advanced tumor model (murine colon 26 (c26) adenocarcinoma, colon 38 (c38) adenocarcinoma, MethA fibrosarcoma, Sarcoma 180 (S180), Lewis lung carcinoma (3LL), human LS180 adenocarcinoma) and an orthotopically transplanted tumor model (c26), compared with that of cisplatin (CDDP). The maximum tolerable dose (MTD) of CDDP suppressed early-stage c26 and c38 tumor growth when treatment was started after the tumor volume (TV) reached 0.2-0.5 cm3, but it showed reduced activity against the same tumors at an advanced growth stage when TV exceeded 2 cm3. At its MTD, AC-7700 was active against all tumors tested except 3LL in both early and advanced growth stages, reducing the tumor mass and having a curative effect in advanced c38 tumors. AC-7700 was also effective on orthotopically transplanted c26 tumors, showing a comparable activity to that on subcutaneous tumors. Unlike flavon acetic acid, which damages tumor vasculature by inducing endogenous tumor necrosis factor-alpha production, AC-7700 potently suppressed the growth of advanced c26 tumors in athymic as well as euthymic mice. These results suggest that AC-7700 is a novel antivascular agent that may have potent activity against advanced-stage cancer in the clinical setting.


Subject(s)
Antineoplastic Agents/therapeutic use , Neoplasms, Experimental/drug therapy , Serine/analogs & derivatives , Animals , Disease Models, Animal , Drug Screening Assays, Antitumor , Female , Humans , Male , Mice , Mice, Inbred BALB C , Mice, Inbred DBA , Mice, Inbred ICR , Neoplasm Transplantation , Serine/therapeutic use , Stilbenes/chemistry , Stilbenes/therapeutic use , Survival Analysis , Transplantation, Heterologous , Tumor Cells, Cultured , Tumor Necrosis Factor-alpha/therapeutic use
19.
J Am Coll Surg ; 189(5): 466-9, 1999 Nov.
Article in English | MEDLINE | ID: mdl-10549735

ABSTRACT

BACKGROUND: Anastomotic stricture is one of the most common problems in esophagojejunostomy using the end-to-end anastomosing (EEA) instrument (Auto Suture Co, Norwalk, CT) after total gastrectomy. To alleviate the stricture, several methods, such as incision to the scar, balloon dilatation, and steroid injection are available. To avoid stricture, the jejunal pouch may allow use of a larger EEA than Roux-en-Y (ReY) reconstruction does. STUDY DESIGN: A total of 45 patients underwent curative total gastrectomy and esophagojejunostomy with jejunal pouch construction (27 patients) or ReY (18 patients), using the EEA. The effects of jejunal pouch construction with a large EEA on avoidance of stricture and benefit to nutritional status were investigated by comparing it with the ReY in terms of postoperative morbidity, postprandial symptoms, and nutritional parameters (serum protein, serum albumin, body weight). RESULTS: EEA28 or larger could be used in 25 patients in the pouch group and 8 patients in the ReY group (p < 0.05). Stricture developed in one patient in the pouch group and in four patients in the ReY group (p < 0.05). Postprandial symptoms were experienced less frequently (p < 0.05) in the pouch group than in the ReY group. When stricture and symptoms were analyzed according to the size of EEA, they occurred more frequently (p < 0.05) in the patients with EEA25 than those with EEA28 or EEA31. No significant differences were evident in nutritional parameters. CONCLUSIONS: The choice of jejunal pouch technique allowed the use of a larger EEA than that of ReY reconstruction, resulting in avoidance of anastomotic stricture and postprandial symptoms, though little benefit in nutritional status was evident to the patients after total gastrectomy.


Subject(s)
Anastomosis, Roux-en-Y/methods , Esophagostomy/methods , Gastrectomy , Jejunostomy/methods , Surgical Staplers , Anastomosis, Roux-en-Y/instrumentation , Case-Control Studies , Chi-Square Distribution , Esophagostomy/instrumentation , Female , Humans , Jejunostomy/instrumentation , Lymph Node Excision , Lymphoma/surgery , Male , Nutritional Status , Postoperative Complications/prevention & control , Postprandial Period , Stomach Neoplasms/surgery , Treatment Outcome
20.
Hepatogastroenterology ; 46(27): 1736-9, 1999.
Article in English | MEDLINE | ID: mdl-10430334

ABSTRACT

A 68 year-old female underwent right hemicolectomy for an advanced cecum cancer and had been well without any evidence of recurrence for a year after surgery. Despite post-operative treatment with oral Tegafur (400 mg/m2/day), CEA level increased gradually beginning 15 months after surgery. Sequential chemotherapy with methotrexate (MTX) and 5-Fluorouracil (5-FU), followed by leucovorin rescue (MFL) was started on an outpatient basis, and has been continued every 4 weeks since then. It consisted of MTX (100 mg/m2) and 5-FU (600 mg/m2) started 24 hours after MTX, followed by oral leucovorin (15 mg/body) started 30 hours after MTX 6 times at intervals of 6 hours. CEA level declined initially, but increased slowly for 3 years on MFL, although no evidence of recurrence was detected by imaging studies with computed tomography, ultrasound, and scintigram. Four years after surgery, a tumor recurrence developed in the abdominal wall. The patient underwent resection of the tumor, resulting in a decline of the CEA level. She has been alive and well for 5 years on MFL after the primary surgery. Both the original tumor and recurrent tumor showed immunoreactivity for P-glycoprotein. The present case demonstrates the feasibility of using MFL on an outpatient basis, and its potential to suppress the colon cancer growth with P-glycoprotein expression.


Subject(s)
ATP Binding Cassette Transporter, Subfamily B, Member 1/analysis , Adenocarcinoma/drug therapy , Antineoplastic Combined Chemotherapy Protocols/therapeutic use , Biomarkers, Tumor/analysis , Cecal Neoplasms/drug therapy , Neoplasm Recurrence, Local/drug therapy , Adenocarcinoma/pathology , Adenocarcinoma/surgery , Aged , Antineoplastic Combined Chemotherapy Protocols/adverse effects , Cecal Neoplasms/pathology , Cecal Neoplasms/surgery , Chemotherapy, Adjuvant , Colectomy , Combined Modality Therapy , Dose-Response Relationship, Drug , Drug Administration Schedule , Female , Fluorouracil/administration & dosage , Fluorouracil/adverse effects , Humans , Leucovorin/administration & dosage , Leucovorin/adverse effects , Methotrexate/administration & dosage , Methotrexate/adverse effects , Neoplasm Recurrence, Local/pathology , Neoplasm Recurrence, Local/surgery
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