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Biomedical subjects

M Tanemura

Publications and source records attributed to M Tanemura.

At least 19 recordsLinked to original sources
PubMed2006

Adenoviral-mediated overexpression of membrane-bound human FasL and human decoy Fas protect pig islets against human CD8+ CTL-mediated cytotoxicity.

Pig islets are considered to be most suitable source of islets for xenotransplantation into patients with type 1 diabetes mellitus. However, cellular rejection, especially CD8+ CTL-mediated cytotoxicity, remains a formidable barrier preventing long-term xenograft survival. Our previous study demonstrated that human CD8+ CTLs were highly detrimental to xenograft cells and that this strong cytotoxicity of human CTLs was mediated mainly by the Fas/FasL apoptotic pathway. Furthermore, we exploited novel methods for inhibiting human CD8+ CTL-mediated xenocytotoxicity with overexpression of membrane-bound human FasL and human decoy Fas antigen in xenografted cells. In the present study, we assessed the cytoprotective effects of these novel inhibitory molecules overexpressed by an adenoviral-mediated system in pig islets. Isolated pig islets were transfected with adenovirus vector encoding either human decoy Fas or membrane-bound human FasL genes. Thirty percent to 60% of transfected pig islets expressed these molecules producing 60% to 88% suppression of CTL killing compared with parental pig islets. These data indicated that pig islet grafts isolated from transgenic pigs with either membrane-bound human FasL or human decoy Fas antigen genes may control the innate cellular response to xenografts, and creating a window of opportunity to facilitate xenograft survival.

Adenoviridae↗
PubMed2006

A novel strategy for preventing human CD8+ cytotoxic T lymphocyte-mediated cytotoxicity against pig endothelial cells by overexpression of pig cellular FLICE-like inhibitory protein (c-FLIP) gene.

Human CD8+ cytotoxic T lymphocyte (CTL)-mediated cytotoxicity in xenograft recipients is an important obstacle for successful xenotransplantation of pig organs into humans. In our previous study, we demonstrated that xenocytotoxicity of human CD8+ CTL detrimental to pig endothelial cells (PEC) is mediated mainly by the Fas/FasL apoptotic pathway. Furthermore, we developed new methods to prevent this CTL killing by extracellular remodeling using overexpression of human decoy Fas antigen and membrane-bound human FasL on pig xenograft cells. The cellular FLICE-inhibitory protein (c-FLIP), a caspase-8 inhibitor that lacks the cysteine domain, is a negative regulator of death receptor-mediated apoptosis. c-FLIP proteins exist as long (c-FLIP(L)) and short (c-FLIPs) splice variants, both capable of protecting cells from death receptor-mediated apoptosis. In this report, we have demonstrated that both pig c-FLIPs and pig c-FLIP(L) significantly inhibit human CD8+ CTL-mediated xenocytotoxicity toward stably transfected PEC, although the expression level of pig Fas antigen on cell surface was not changed. These data suggested that intracellular remodeling with overexpression of pig c-FLIP in xenograft cells may decrease the innate cellular responses against xenografts, facilitating long-term xenograft survival.

Animals↗
PubMed2006

Regulation of donor T cells in the tolerant rats to graft-versus-host disease by FTY720 following small bowel transplantation.

AIMS: The potency of immunosuppression is a critical factor in small bowel transplantation (SBTx). FTY720 altered lymphocyte trafficking and prevented the donor T cells from migrating into target organs, resulting in the prolongation of recipient survival in acute graft-versus-host disease (GVHD) of SBTx. However, the effect of FTY720 on donor T cells in the chronic phase of GVHD following SBTx remains unclear. METHODS: Heterotopic SBTx was performed in a WF-to-F1 (WF x ACI) rat combination. Recipients were given FTY720 for 14 days after SBTx. The subpopulations of donor-derived T cells and the cytokine production in the target tissues were evaluated on postoperative day 150. RESULTS: FTY720 treatment significantly prolonged recipient survival over 150 days without any clinical signs of GVHD. The numbers of donor-derived CD4+ and CD8+ T cells in the peripheral blood, mesenteric lymph nodes, and Peyer's patches of recipients were maintained at low levels on postoperative 150, which were almost similar to the levels on postoperative day 14. In the host lamina propria, however, a significant higher number of donor T cells (CD4+, 18.4 +/- 4.3 x 10(4); CD8+, 13.9 +/- 3.6 x 10(4)) were still observed on postoperative day 150. Production of interferon-gamma was significantly reduced in target tissues by FTY720 treatment both in the acute and chronic phase. However, interleukin-4 and interleukin-10 production, which was significantly higher on day 14, returned to the level of naive rats in the chronic phase. CONCLUSIONS: A 14-day treatment of FTY720 induced tolerance in our SBTx model. Down-regulation of both Th1 and Th2 immune response was observed in the chronic phase.

Animals↗
PubMed2006

Inhibition of donor-derived T cells trafficking into target organs by FTY720 during acute graft-versus-host disease in small bowel transplantation.

In small bowel transplantation (SBTx), graft-versus-host disease (GVHD) is mediated by donor-derived T cells recognizing host major histocompatibility complex (MHC) alloantigens, and represents an important immunological event influencing life in experimental and clinical situations. We evaluated the possibility that a new sphingosine 1-phosphate receptor agonist, FTY720, could diminish GVHD in a rat SBTx model through traffic alteration of donor-derived T cells in target organs. Heterotopic SBTx was performed using a parent (WF)-into-F(1) (WF x ACI) rat combination. Recipient survival, body weight, histopathology, donor-derived T cell subpopulation and cytokine production were compared with untreated controls. FTY720 inhibited lethality and histopathological changes in target organs when administered at 0.5 mg/kg, possibly due to sequestration of donor-derived T cells in the intestinal graft. FTY720 caused a significant reduction in donor T cell numbers in target organs by promoting these cells to home into donor, but not recipient, secondary lymphoid tissues. FTY720 significantly decreased production of interferon (IFN)-gamma in target organs. These findings indicate that FTY720 effectively reduced recirculation of activated donor-derived T cells and recruitment to target organs in GVHD, and was also associated with down-regulated IFN-gamma production. These properties may offer the potential to treat ongoing GVHD in SBTx.

Acute Disease↗
PubMed2005

Synergistic effects on the inhibition of human CD8+ cytotoxic T lymphocytes-mediated killing against xenograft cells by coexpression of membrane-bound Human FasL and decoy Fas antigen.

The principal barrier to the use of pigs as donors to humans is hyperacute rejection mediated by the interaction of alpha-gal abundantly expressed on pig cells and the natural anti-Gal antibody, abundantly produced in humans. This antibody-mediated hyperacute rejection may be overcome by an alpha1, 3 galactosyltransferase gene-knockout pig. However, xenograft cells could be rejected by T cells, especially CD8+ cytotoxic T lymphocytes (CTL)-mediated response, because these elements show great cytotoxicity against xenografted cells. We previously demonstrated that the Fas/FasL pathway is a major contributor to CD8+ CTL function. Furthermore, we sought to prevent this cytotoxicity by overexpression of membrane-bound FasL carrying the deletion at the metalloproteinase cleavage site or by decoy Fas antigen that does not contain the death domain in its cytoplasmic region. To investigate the effects of coexpression of these molecules, we cotransfected both genes into swine endothelial cells (SEC). The double-overexpression effectively prevented CD8+ CTL-mediated killing. Although cotransfectants and single transfectants of either membrane-bound FasL or decoy Fas gene showed similar inhibition of cytotoxicity, the expression levels of decoy Fas in SEC cotransfectants were much lower than those of decoy Fas single transfectants. These data suggest that beneficial effects for prevention of CTL-mediated xenocytotoxicity may be produced by the double expression of these molecules. The overexpression of both molecules on xenografted cells may decrease the innate cellular response to xenografts creating a window of opportunity to facilitate xenograft survival.

Acute Disease↗
PubMed2004

Advantages of laparoscope-assisted surgery for recurrent Crohn's disease.

BACKGROUND: Laparoscopic surgery has been applied to patients with primary Crohn's disease, and its beneficial outcomes have been already investigated. However, there is no systematic study of laparoscopic surgery for patients with recurrent diseases. METHODS: We performed reoperation for 43 patients with recurrent Crohn's disease, including 23 patients who underwent laparoscope-assisted surgery. RESULTS: For all the patients, laparoscope-assisted surgery could be performed safely, even if the patients had been treated previously by open surgery or had undergone multiple abdominal procedures. Conversion to open or hand-assisted laparoscopic surgery was necessary for 16 patients (69.6%) because of dense adhesions (11 cases) or bulky tumor (5 cases). Importantly, even if the procedure was converted, the skin incision was significantly shorter than with open surgery, and postoperative recovery was faster, especially for the patients who underwent conversion to hand-assisted laparoscopic surgery. CONCLUSIONS: Laparoscope-assisted surgery is feasible and advantageous in reoperation for patients with recurrent Crohn's disease.

Adult↗
PubMed2001

Multicolour spectral karyotyping for complex chromosomal rearrangements in repeated abortion or congenital anomalies.

Advances in molecular cytogenetics, especially the technique of fluorescence in situ hybridization (FISH), have allowed more precise definition of chromosomal structures, which are difficult to identify using conventional G-banding. Recently, a novel approach based on hybridization of 24 fluorescent-labelled chromosome painting probes was developed, termed spectral karyotyping (SKY), which allows the simultaneous and differential colour display of all human chromosomes. We have used SKY to identify not only five parental complex translocation carriers but also minute chromosome rearrangements in the fetus. Here, we concentrate attention on the clinical application of SKY for prenatal diagnosis.

Abortion, Habitual↗
PubMed2001

Modeling the electron field emission from carbon nanotube films.

A theoretical framework for the electron field emission from carbon nanotubes (CNTs) is discussed. Using the tunneling theory, the influence of the detailed electron energy dispersion is proven to be of little importance for the electron field emission. By means of numerical computations in a simplified model, the influence of the environment on the local field on a CNT is discussed for an aligned CNT film. In a simple triangular model for the potential energy barrier at the tube end, a tunneling probability was obtained. A statistical model was developed for the structural and functional parameters of aligned CNT films. Practical CNT films of excellent alignment, obtained directly on a tungsten wire by plasma-enhanced chemical vapor deposition, were analyzed by this statistical model. Their distribution in the enhancement factors was thus deduced. An indirect method to get the average electrical parameters of the film using only a limited amount of experimental data was thus established.

Journal Article↗
PubMed2001

Spatial data analysis by epidermal Langerhans cells reveals an elegant system.

Langerhans cells are dendritic cells situated in the mammalian epidermis. In human epidermis, the concentration is between 460 and 1000 mm(-2). Langerhans cells fulfill an essential role in skin immune responses. Numerous scientific reports on Langerhans cells have appeared, but with no systematic research on the pattern of the spatial distributions. On the contrary, in certain fields, a spatial distribution is an important theme, and spatial data analysis has a long history. We hypothesized that epidermal Langerhans cells were set in the best formation for their immuno-surveillance by a sophisticated mechanism. To prove this hypothesis, we have imported spatial data analysis into the study of epidermal Langerhans cells. Here, we show that the distribution is completely regular; the pattern of Voronoi divisions fits the territories; the random packing model simulates their bone marrow derivation; a repulsive interaction is demonstrated and a repulsive potential function is estimated. Spatial data analysis-based computer simulation will be a new method of Langerhans cell study. In addition, this procedure shows promise for future distribution research of certain cells.

Animals↗
PubMed2001

A case of successful fetal therapy for congenital chylothorax by intrapleural injection of OK-432.

A 38-year-old multiparous woman was referred at 19 weeks' gestation because of hydrops fetalis. Ultrasonic examination revealed severe pleural effusion, ascites and skin edema. Detailed examination of the amniotic fluid, fetal blood and intrathoracic fluid led to a diagnosis of congenital fetal chylothorax. Repeated thoracocenteses were not effective in improving the hydrops fetalis. We introduced fetal treatment for the pleural effusion by an intrapleural injection of OK-432 at 23, 24 and 25 weeks' gestation. The pleural effusion was reduced by adhesion of the intrathoracic space and resulted in the delivery of a neonate who was healthy except for right renal dysfunction. Pulmonary hypoplasia was successfully prevented by OK-432.

Adult↗
PubMed2001

Synthesis of alpha-gal epitopes (Galalpha1-3Galbeta1-4GlcNAc-R) on human tumor cells by recombinant alpha1,3galactosyltransferase produced in Pichia pastoris.

This study describes the processing of human tumor cells or cell membranes to express alpha-gal epitopes (Galalpha1-3Gal-beta1-4GlcNAc-R) by the use of New World monkey (marmoset) recombinant alpha1,3galactosyltransferase (ralpha1,3GT), produced in the yeast Pichia pastoris. Such tumor cells and membranes may serve, in cancer patients, as autologous tumor vaccines that are targeted in vivo to antigen-presenting cells by the anti-Gal antibody. This ralpha1,3GT lacks transmembrane and cytoplasmic domains, ensuring its solubility without detergent. It is effectively produced in P. pastoris under constitutive expression of the P(GAP) promoter and is secreted into the culture medium in a soluble, truncated form fused to a (His)(6) tag. This tag enables the simple affinity purification of ralpha1,3GT on a nickel-Sepharose column and elution with imidazole. The purified enzyme appears in SDS-PAGE as two bands with the size of 40 and 41 kDa and displays the same acceptor specificity as the mammalian native enzyme. ralpha1,3GT is very effective in synthesizing alpha-gal epitopes on membrane-bound carbohydrate chains and displays a specific activity of 1.2 nM membrane bound alpha-gal epitopes/min/mg. Incubation of very large amounts of human acute myeloid leukemia cells (1 x 10(9 )cells) with neuraminidase, ralpha1,3GT, and UDP-Gal resulted in the synthesis of approximately 6 x 10(6 )alpha-gal epitopes per cell. Effective synthesis of alpha-gal epitopes could be achieved also with as much as 2 g cell membranes prepared from the tumor of a patient with ovarian carcinoma. These data imply that ralpha1,3GT produced in P. pastoris is suitable for the synthesis of alpha-gal epitopes on bulk amounts of tumor cells or cell membranes required for the preparation of autologous tumor vaccines.

Electrophoresis, Polyacrylamide Gel↗
PubMed2000

Differential expression of alpha-GAL epitopes (Galalpha1-3Galbeta1-4GlcNAc-R) on pig and mouse organs.

BACKGROUND: Expression of the alpha-gal epitope in mice can be completely eliminated by disruption of the alpha1,3 galactosyltransferase gene. As an initial step for assessing the feasibility of this approach in the pig, it was of interest to compare the expression of alpha-gal epitopes in pig and mouse organs. METHODS: Membranes from pig and mouse organ homogenates were analyzed for alpha-gal epitope expression by Western blots, enzyme-linked immunosorbent assay (ELISA), immunostaining of tissues, and ELISA inhibition assay. RESULTS: Immunostaining of Western blots with human anti-Gal detected alpha-gal epitopes on glycoproteins from pig organs but not on glycoproteins from the corresponding mouse organs. ELISA with membrane homogenates and immunostaining of tissue sections demonstrated a much higher binding of human anti-Gal to alpha-gal epitopes on pig membranes than on mouse membranes. ELISA inhibition assay with monoclonal anti-Gal indicated that alpha-gal epitope expression in pig organs is up to 500-fold higher than in mouse organs. CONCLUSION: Expression of alpha-gal epitopes in pig organs is many fold higher than in mouse organs. The abundance of these epitopes in pigs raises the question of whether pigs can properly develop without expression of alpha-gal epitopes.

Animals↗
PubMed2000

Differentiation of wing epidermal scale cells in a butterfly under the lateral inhibition model--appearance of large cells in a polygonal pattern.

Cellular pattern formations of some epithelia are believed to be governed by the direct lateral inhibition rule of cell differentiation. That is, initially equivalent cells are all competent to differentiate, but once a cell has differentiated, the cell inhibits its immediate neighbors from following this pathway. Such a differentiation repeats until all non-inhibited cells have differentiated. The cellular polygonal patterns can be characterized by the numbers of undifferentiated cells and differentiated ones. When the differentiated cells become large in size, the polygonal pattern is deformed since more cells are needed to enclose the large cell. An actual example of such a cellular pattern was examined. The pupal wing epidermis of a butterfly Pieris rapae shows a transition of the equivalent-size cell pattern to the pattern involving large cells. The process of the transition was analyzed by using the method of weighted Voronoi tessellation that is useful for treatment of irregularly sized polygons. The analysis supported that the pattern transition of the early stage of the pupal wing epidermis is governed by the lateral inhibition rule. The differentiation takes place in order of largeness, but not smallness, of the apical polygonal area in the differentiating region of the pupal wing.

Animals↗