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T Koshiba

Publications and source records attributed to T Koshiba.

At least 19 recordsLinked to original sources
PubMed2006

Liver transplantation from an identical twin without immunosuppression, with early recurrence of hepatitis C.

Hepatitis C virus reinfection after liver transplantation is universal and more severe than in nontransplant patients. Rejection episodes and immunosuppressive agents are considered risk factors for deterioration of recurrent hepatitis C. We report 2 cases of living donor liver transplantation for patients with hepatitis C-related cirrhosis who received right-lobe grafts from an identical twin. Thanks to genetic identity, no immunosuppressive drugs were administered during or after transplantation without rejection. Hepatitis C virus RNA kinetics showed a rapid increase following transplantation and liver biopsies 1 month after transplantation showed acute lobular hepatitis in both cases. Antiviral therapy using interferon alpha and ribavirin was started immediately, and both cases showed virological and histological response. In conclusion, avoidance of immunosuppression did not delay hepatitis C recurrence following transplantation, while early antiviral therapy without risk of rejection or immunosuppression led to successful viral eradication.

Adult↗
PubMed2003

Break of tolerance via donor-specific blood transfusion by high doses of steroids: a differential effect after intestinal transplantation and heart transplantation.

UNLABELLED: Tolerance requires active mechanisms. How immunosuppressors affects tolerance is poorly understood. METHODS: RA (RT1(p))/PVG (RT1(c)) rats were used as donor/recipient. Intestinal and heart transplant model were selected as highly and poorly immunogenic organs. Studied groups were 1, rejecting control; 2, received peritransplant steroids; 3, donor-specific blood transfusion (DSBT); 4, DSBT plus peritransplant steroids; and 5, DSBT+periDSBT Ste. RESULTS: Intestinal transplant recipients in group 1 died on posttransplant day (d) 18. In group 2, steroids did not change survival (17 days, P >.05 versus group 1). With DSBT (group 3), all rats survived >75 days, whereas with steroids those in group 4 survived 59 days (P >.05 vs group 3) and group 5 survived 51 days (P <.05 versus group 3). Survivors in group 2 were tolerant as evidenced by acceptance of secondary donor-specific (not third-party) graft. However, 100% and 33% of donor-specific secondary grafts were rejected in groups 4 and 5 (P <.05 and P >.05 versus group 3). In heart transplants, steroid treatment had no effect on graft survival (group 1 9 days; group 2 9 days; P >.05). DSBT (group 3) induced 100% tolerance (primary: >100 days, secondary: 100%). Unlike in intestinal transplantation, adjunction peritransplant steroids (group 4) allowed 100% of primary and 83% of secondary graft acceptance (P >.05 versus group 3). In group 5, (DSBT+periDSBT steroids) acceptance of primary and secondary grafts tended to be reduced (primary: 77 days; P >.05 versus group 3; secondary: 67%, P >.05 versus group 3). CONCLUSION: Steroid induction did not prolong graft survival after either intestinal or heart transplant. Adjunction of steroids to a DSBT tolerogenic regimen caused rejection of primary and secondary grafts, particularly after intestinal transplantation. Routine use of steroids in the clinics must be reconsidered, particularly when immunogenic organs are transplanted and when immunomodulation is applied.

Animals↗
PubMed2002

Antiproliferative activity induced by the somatostatin analogue, TT-232, in human pancreatic cancer cells.

Somatostatin analogues have been developed as antiproliferative agents, but their administration as general antitumour agents is limited, mainly because of the wide distribution of somatostatin receptors throughout the human body. TT-232, a new somatostatin structural analogue, was reported to have tumour-selective antiproliferative activity without an antisecretory action. We examined whether TT-232 had antiproliferative activity in human pancreatic cancer cell lines, and compared its antiproliferative activity with that of RC-160 and other TT-232 derivatives. TT-232 inhibited the growth of all of the cell lines used in this study and induced apoptotic cell death. RC-160 showed no such growth inhibition. TT-232 also inhibited tumour formation in a xenograft model. A competitive binding assay was performed using the cell membrane fraction and 111In-DTPA-TT-232 in order to show the existence of a specific binding site on the cells. A specific binding site was detected in MIAPaCa-2 cells. It has been shown that the activation of protein tyrosine phosphatase (PTPase) is one of the main intracellular pathways responsible for somatostatinergic inhibition of cell growth. We found a significant PTPase stimulation after TT-232 administration using an immunoblot analysis assessing the level of protein tyrosine phosphorylation, and also a direct measurement of the PTPase activity. We also demonstrated that PTPase stimulation by TT-232 was involved in its antiproliferative activity as this activity was reversed by the addition of sodium orthovanadate, a PTPase inhibitor. Our results indicate that TT-232 could be a potentially useful therapeutic agent if these data are translated into clinical practice.

Antineoplastic Agents↗
PubMed2001

Effects of substituent and temperature on enantioselectivity for lipase-catalyzed esterification of 2-(4-substituted phenoxy) propionic acids in organic solvents.

Substituent effects on the enantioselectivity for the lipase-catalyzed esterifications in organic solvents were studied by use of 2-(4-substituted phenoxy)propionic acids as the substrates with various substituents of H, F, Cl, CF(3), CH(3), CH(3)CH(2), and CH(3)O. The distinction in the behavior of their enantioselectivity was primarily responsible for the size effects of the substituents, although the substituents are far away from the stereocenter of the substrates. For the similar substituents in size, CH(3) and CF(3), however, their electronic effects played an important role in controlling the enantioselectivity. This variation of the enantioselectivity due to the electronic effects is also supported by the discussion based on the value of the Michaelis constant (K(m)) obtained. In addition, by raising the reaction temperature with enough water added to isopropyl ether as the reaction medium, the enantioselectivity is found to be dramatically enhanced for the substrate bearing CH(3)O group due to the strong electron-donating effect.

Candida↗
PubMed2001

Oxidative folding of human lysozyme: effects of the loss of two disulfide bonds and the introduction of a calcium-binding site.

Mutant human lysozymes (HLZ) lacking two disulfide bonds were constructed to study the importance of each disulfide bond on oxidative refolding. To avoid destabilization, a calcium-binding site was introduced. Five of the six species of two-disulfide mutants could be obtained with enzymatic activity. Based on the information obtained from refolding and unfolding experiments, the order of importance in oxidative refolding was found to be as follows: SS2(Cys30-Cys116) > SS1(Cys6-Cys128) approximately SS3(Cys65-Cys81) > SS4(Cys77-Cys95). Without SS2, these mutants refolded with low efficiency or did not refold at all. The bond SS2 is located in the interface of B-and D-helices, and a small hydrophobic cluster is formed near SS2. This cluster may play an important role in the folding process and stabilization, and SS2 may act as a stabilizer through its polypeptide linkage. The bond SS2 is the most important disulfide bond for oxidative folding of lysozymes.

Binding Sites↗
PubMed2001

Recent advances and future prospects in intestinal and multi-visceral transplantation.

From an experimental procedure, intestinal transplantation (ITx) has evolved over the last 10 yr into a treatment option for patients suffering from short bowel syndrome and who develop life-threatening complications from total parenteral nutrition (TPN) (e.g. liver dysfunction, line sepsis, shortage of venous access, etc.). One-year survival rates are approximately 70% and thus similar to lung Tx. However, the intestine remains the most challenging abdominal organ to transplant. This is because of the severe immune response (mostly rejection) that is produced, and therefore the need for profound immunosuppression with its attendant complications (sepsis, lymphoma, direct drug toxicity). Unlike other organs, graft loss as a result of acute rejection can occur late after transplantation (more than 1 yr post-transplant). With regard to the actual immunosuppressive regimens, considerable experience in patient management is required to optimize outcome of those complex transplants, which are permanently at risk of rejection and infection. ITx remains an unfinished product, and the application of ITx to patients doing well on TPN warrants further research in the understanding of the rejection process, in the development of less toxic and more efficient immunosuppressive protocols, and in the development of immunomodulatory strategies, to better control rejection and thereby reduce the need for immunosuppression.

Adjuvants, Immunologic↗
PubMed2001

Liver transplantation for polycystic liver disease.

Polycystic liver disease (PLD) may provoke massive hepatomegaly and severe physical and social handicaps. Data on orthotopic liver transplantation (OLT) for PLD are rare and conflicting. Conservative surgery (resection or fenestration) is indicated for large single cysts, but its value for small diffuse cysts is questionable. In addition, conservative surgery is not devoid of morbidity and mortality. OLT offers the prospect of a fully curative treatment, but controversy remains because those patients usually have preserved liver function. Thus, we reviewed our experience with OLT for PLD. Sixteen adult women underwent OLT for small diffuse PLD between 1990 and 1999. Mean age was 45 years (range, 34 to 56 years). Fourteen patients had combined liver and kidney cystic disease, but only 1 patient required combined liver and kidney transplantation, whereas 13 patients underwent OLT alone. Two patients had isolated PLD. Indications for transplantation were massive hepatomegaly causing physical handicaps (n = 16), social handicaps (n = 16), malnutrition (n = 4), and cholestasis and/or portal hypertension (n = 5). OLT caused no technical difficulty in 15 of 16 patients (surgery duration, 6.8 hours; range, 5 to 8 hours), with blood transfusions of 7.9 units (range, 0 to 22 units). One patient who underwent attempted liver-mass reduction pre-OLT died of bleeding and pulmonary emboli. Native liver weight was 10 to 20 kg. Posttransplantation immunosuppression consisted of cyclosporine or FK506, azathioprine, and steroids (discontinued at 3 months). Morbidity included biliary stricture (2 patients), revision for bleeding and hepatitis (1 patient), pneumothorax and subphrenic collection (1 patient), and tracheostomy (1 patient). One patient died of lung cancer 6 years posttransplantation. Both patient and graft survival rates are 87.5% (follow-up, 3 months to 9 years). Of 15 patients who underwent OLT alone, only 1 patient needed a kidney transplant 4 years after OLT. Kidney function has remained satisfactory in the other patients despite the use of cyclosporine or FK506 (last follow-up creatinine level, 1.55 mg/dL; range, 0.80 to 2.85 mg/dL). OLT had a dramatic impact on daily quality of life, enabling these patients to go back to a fully active life style. OLT offers the chance of a definitive treatment in patients with extensive, small, diffuse PLD that has evolved into severely handicapping hepatomegaly. In contrast to previous studies, combined liver and kidney transplantation is rarely needed. Patient symptoms and chances of definitive palliation offered by OLT must be balanced against the risks of transplantation and lifelong commitment to immunosuppression.

Adult↗
PubMed2001

Type of donor aortic preservation solution and not cold ischemia time is a major determinant of biliary strictures after liver transplantation.

The development of biliary strictures (BSs) after liver transplantation (LT) continues to affect 10% to 30% of patients, causing substantial morbidity. The cause of BSs is multifactorial, including technical, immune, and, in particular, ischemic factors. The importance of adequate flushing of the peribiliary arterial tree has been stressed. We hypothesized that high-viscosity (HV) preservation solutions in the donor do not completely flush the small donor peribiliary plexus, leading to inadequate preservation of the bile ducts and posttransplant BSs. To test this hypothesis, we retrospectively compared the incidence of BSs in 2 groups of adults undergoing LT using different types of aortic preservation solution in the donor: group 1 (n = 24), low-viscosity (LV) Marshall solution; and group 2 (n = 27), HV University of Wisconsin (UW) solution. All donors in both groups received additional portal flushes with UW. All LTs were performed between November 1995 and August 1998 at 2 centers by the same surgeon, eliminating a technical bias. Terminal duct-to-duct anastomosis was performed in all recipients except 1 patient in group 1, who underwent a bile duct-to-jejunum anastomosis. BSs were first suspected on clinical and biochemical grounds and then confirmed by endoscopic retrograde cholangiopancreatography. Identical medical protocols were used in all patients. One-year patient survival rates in groups 1 and 2 were 92% and 100%, respectively (P =.9). One-year graft survival was identical to patient survival. The incidence of BSs in group 1 was 4.1% (1 of 24 patients), compared to 29.7% in group 2 (8 of 27 patients; P =.02). The BS in group 1 occurred 4 months post-LT and was anastomotic. BSs in group 2 occurred between 1 and 12 months post-LT and were anastomotic, extrahepatic, intrahepatic, or combined intrahepatic and extrahepatic. There were no significant differences in the following factors between groups 1 and 2: donor age, local versus imported liver, split-liver or full-liver transplantation, incidence of multiple vessels in the donor liver, indications for LT, recipient age, T-tube versus no T-tube, post-LT peak aspartate aminotransferase level, and treatment for rejection. There was no hepatic artery thrombosis or primary nonfunction in either group. Interestingly, cold ischemia time (CIT) was longer in group 1, which had the least incidence of BSs (692 +/- 190 v 535 +/- 129 minutes in group 2; P =.001). Follow-up was longer in group 1 (28.9 +/- 8.3 v 15.6 +/- 8 months in group 2; P =.0001). Preservation costs per procurement were 1.9 times greater in the UW group than in the Marshall group. Donor aortic flushing with an HV preservation solution leads to more frequent BSs compared with an LV preservation solution. The impact of preservation solution outweighs the previously described deleterious impact of prolonged CIT. Mixed preservation solution (Marshall solution in the aorta, UW solution in the portal vein) might protect against BS formation while providing optimal liver graft preservation, function, and survival despite a mean CIT longer than 10 hours.

Adenosine↗
PubMed2001

Energetics of three-state unfolding of a protein: canine milk lysozyme.

Thermodynamics of thermal transitions of a calcium-binding lysozyme, canine milk lysozyme (CML), was studied using differential scanning calorimetry and compared with those for homologous proteins, human alpha-lactalbumin (alpha-hLA) and equine milk lysozyme (EML). The results showed that CML and EML exhibit two clear heat absorption peaks in the absence of calcium ions (apo-form), although the cooperative thermal transition of alpha-hLA is apparently absent in this form. The first peak represents the unfolding transition from the native to an unfolding intermediate state (N-I transition) and the second peak represents that from the intermediate to the thermally unfolded state (I-U transition). We interpret that the cooperative thermal transition, which is observed between the intermediate and the thermally unfolded states of CML and EML, comes from the native-like packing interaction in their intermediate states. Furthermore, to examine the role of the stabilization mechanism of CML intermediate, we constructed four variant CMLs (H21G, I56L, A93S and V109K), in which the residues of CML are substituted for those of EML, and also investigated their thermal stability. Especially the His21 and Val109 of CML play a role in stabilization of the intermediate state and their contributions to the unfolding free energy are estimated to be 2.0 and 1.8 kJ/mol, respectively. From the results of the mutational analysis, a few differences in the local helical interactions within the alpha-domain are found to be predominant in stabilizing the intermediate state.

Animals↗
PubMed2000

Nitric oxide synthase is induced in tumor promoter-sensitive, but not tumor promoter-resistant, JB6 mouse epidermal cells cocultured with interferon-gamma-stimulated RAW 264.7 cells: the role of tumor necrosis factor-alpha.

Expression of inducible nitric oxide synthase (iNOS) has been reported to be involved in certain organs of potential tumorigenesis, including the stomach and colon. The mechanisms for iNOS expression in epithelial cells, however, are not fully understood. In the present study, we investigated the role of macrophages in epithelial iNOS expression by coculturing a stimulated murine macrophage-like cell line, RAW 264.7, with either tumor promoter-sensitive (P+) or promoter-resistant (P-) JB6 murine epidermal cells. After monoculture, treatment of RAW 264.7 cells with IFN-gamma for 24 h generated a large amount of nitrite (NO2-), as reported previously, whereas no increase in NO2- concentration was observed in the IFN-gamma-treated P+ or P-subclones. Interestingly, when IFN-gamma-treated RAW 264.7 cells were cocultured with P+ but not P- cells, we observed a marked increase in NO2- concentration (30.8+/-3.6 microM), which significantly exceeded (P < 0.01) the sum of the concentrations (20.0+/-2.3 microM) added from each cell line monoculture. Western blotting analysis revealed that, after coculture, iNOS protein was up-regulated 55-fold more than the control in JB6 P+ but not in P- cells. IFN-gamma-treated RAW 264.7 cells secreted proinflammatory cytokines, including tumor necrosis factor (TNF)-alpha and interleukin (IL)-1beta. The addition of IFN-gamma-treated RAW 264.7 cell-conditioned media to P+ subclones led to a significant enhancement of NO2- formation that was diminished by the TNF-alpha-specific but not IL-1beta-specific antibody. When combined with IFN-gamma, the recombinant TNF-alpha (1-100 ng/ml) enhanced NO2- formation in JB6 P+ cells, whereas IL-1beta (1-100 ng/ml) did not. These results led us to conclude that IFN-gamma-treated RAW 264.7 cells release TNF-alpha to induce iNOS expression in promoter-sensitive JB6 cells. Thus, we propose the hypothesis that macrophages stimulate neoplastic cells with TNF-alpha via a paracrine loop to induce epithelial iNOS protein expression.

Animals↗
PubMed2000

The Arabidopsis aldehyde oxidase 3 (AAO3) gene product catalyzes the final step in abscisic acid biosynthesis in leaves.

Abscisic acid (ABA) is a plant hormone involved in seed development and germination and in responses to various environmental stresses. The last step of ABA biosynthesis involves oxidation of abscisic aldehyde, and aldehyde oxidase (EC ) is thought to catalyze this reaction. An aldehyde oxidase isoform, AOdelta, encoded by AAO3, one of four Arabidopsis aldehyde oxidase genes (AAO1, AAO2, AAO3, and AAO4), is the most likely candidate for the enzyme, because it can efficiently catalyze the oxidation of abscisic aldehyde to ABA. Here, we report the isolation and characterization of an ABA-deficient Arabidopsis mutant that maps at the AAO3 locus. The mutant exhibits a wilty phenotype in rosette leaves, but seed dormancy is not affected. ABA levels were significantly reduced in the mutant leaves, explaining the wilty phenotype in rosettes, whereas the level in the mutant seeds was less reduced. No AOdelta activity could be detected in the rosette leaves of the mutant. Sequence data showed that the mutant contains a G to A substitution in the AAO3 gene. The mutation causes incorrect splicing of the ninth intron of AAO3 mRNA. We thus conclude that the ABA-deficient mutant is impaired in the AAO3 gene and that the gene product, AOdelta, is an aldehyde oxidase that catalyzes the last step of ABA biosynthesis in Arabidopsis, specifically in rosette leaves. Other aldehyde oxidases may be involved in ABA biosynthesis in other organs.

Abscisic Acid↗
PubMed2000

Inhibition of pRb phosphorylation and cell cycle progression by an antennapedia-p16(INK4A) fusion peptide in pancreatic cancer cells.

In this study, we examined whether or not a small peptide derived from p16(INK4A) protein with the antennapedia carrier sequence could inhibit the growth of pancreatic cancer cells through the inhibition of cell cycle progression. Growth inhibition by the p16-derived peptide was observed in a time- and dose-dependent manner in AsPC-1 and BxPC-3 cells (p16-negative and pRb-positive), whereas Saos-2 cells (p16-positive and pRb-negative) showed no inhibitory effect. In AsPC-1 and BxPC-3 cells, the proportion of cells in the G(1) phase markedly increased 48 h after treatment with 20 microM p16-derived peptide. Cell-cycle analysis of Saos-2 cells showed little change during the entire period of treatment. Immunoblot analysis showed inhibition of pRb phosphorylation after treatment of BxPC-3 with 10 microM p16 peptide. Furthermore, the p16 peptide caused a decrease in cyclin A at later times of treatment. These results demonstrate that the p16-derived peptide can inhibit the growth of p16-negative and pRb-positive pancreatic cancer cells by means of G(1) phase cell cycle arrest resulting from the inhibition of pRb phosphorylation. Restoration of p16/pRb tumor-suppressive pathway by re-expression of p16(INK4A) may play a therapeutic role in the treatment of pancreatic cancer.

Amino Acid Sequence↗
PubMed2000

Molecular cloning and expression patterns of three putative functional aldehyde oxidase genes and isolation of two aldehyde oxidase pseudogenes in tomato.

The final steps in the biosynthesis of the plant hormones abscisic acid (ABA) and indole-3-acetic acid (IAA) have been shown to be catalyzed by aldehyde oxidases (AO). We have cloned three putative functional AO genes (TAO1, TAO2 and TAO3) and two putative AO pseudogenes (TAO4 and TAO5) in tomato. The TAO1 cDNA described here includes the correct amino terminus of the encoded TAO1 protein and is different at the 5'-end from the TAO1 sequence in GenBank (accession number U82558). Northern analysis shows that TAO1 is expressed mainly in vegetative tissues and TAO2 is expressed in both vegetative and reproductive tissues. TAO3 expression was not detectable by Northern hybridization. These results suggest that each AO may play different roles in the regulation of tomato growth and development.

Aldehyde Oxidase↗
PubMed2000

Inhibitory effect of citrus nobiletin on phorbol ester-induced skin inflammation, oxidative stress, and tumor promotion in mice.

The intake of citrus fruits has been suggested as a way to prevent the development of some types of human cancer. Nitric oxide (NO) is closely associated with the processes of epithelial carcinogenesis. We attempted a search for NO generation inhibitors in Citrus unshiu. The active constituent was traced by an activity-guiding separation. NO and superoxide (O2-) generation was induced by a combination of lipopolysaccharide and IFN-gamma in mouse macrophage RAW 264.7 cells, and by 12-O-tetradecanoylphorbol-13-acetate (TPA) in differentiated human promyelocyte HL-60, respectively. Expression of inducible NO synthase and cyclooxygenase 2 proteins were detected by Western blotting. The in vivo anti-inflammatory and antitumor promoting activities were evaluated by topical TPA application to ICR mouse skin with measurement of edema formation, epidermal thickness, leukocyte infiltration, hydrogen peroxide production, and the rate of proliferating cell nuclear antigen-stained cells. As a result, nobiletin, a polymethoxyflavonoid, was identified as an inhibitor of both NO and O2- generation. Nobiletin significantly inhibited two distinct stages of skin inflammation induced by double TPA application [first stage priming (leukocyte infiltration) and second stage activation (oxidative insult by leukocytes)] by decreasing the inflammatory parameters. It also suppressed the expression of cyclooxygenase-2 and inducible NO synthase proteins and prostaglandin E2 release. Nobiletin inhibited dimethylbenz[a]anthracene (0.19 micromol)/TPA (1.6 nmol)-induced skin tumor formation at doses of 160 and 320 nmol by reducing the number of tumors per mouse by 61.2% (P < 0.001) and 75.7% (P < 0.001), respectively. The present study suggests that nobiletin is a functionally novel and possible chemopreventive agent in inflammation-associated tumorigenesis.

Animals↗