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Biomedical subjects

S Takemoto

Publications and source records attributed to S Takemoto.

At least 19 recordsLinked to original sources

Five-year results of a randomized, single-center study of tacrolimus vs microemulsion cyclosporine in heart transplant patients.

BACKGROUND: Previous multicenter, randomized trials, lacking standardized post-transplant protocols, have compared tacrolimus (Tac) and cyclosporine (CyA, Sandimmune) and demonstrated similar outcomes with some different adverse effects. The microemulsion form of CyA (mCyA, Neoral) has replaced Sandimmune CyA as the more widely utilized CyA formulation. This is the first 5-year follow-up study of a large, single-center trial (n = 67) under a standardized post-transplant protocol comparing Tac and mCyA. METHODS: Sixty-seven heart transplant patients were randomized to Tac (n = 33) or mCyA (n = 34), both in combination with corticosteroids and azathioprine without cytolytic induction. Five-year end-points included survival, Grade > or = 3A or treated rejection, angiographic cardiac allograft vasculopathy (CAV; any lesion > or = 30% stenosis), renal dysfunction (creatinine > or = 2.0 mg/dl), use of two or more anti-hypertensive medications, percent diabetic and lipid levels. RESULTS: Five-year survival, freedom from Grade > or = 3A or any treated rejection and angiographic CAV, mean cholesterol level and percent diabetic were similar between the two groups. The Tac group had a significantly lower 5-year mean triglyceride level (Tac 97 +/- 34 vs mCyA 175 +/- 103 mg/dl, p = 0.011) and average serum creatinine level (Tac 1.2 +/- 0.5 mg/dl vs mCyA 1.5 +/- 0.4 mg/dl, p = 0.044). There was a trend toward fewer patients requiring two or more anti-hypertensive drugs in the Tac group (Tac 33% vs mCyA 59%, p = 0.065). CONCLUSIONS: Tac and mCyA appear to be comparable with regard to 5-year survival, freedom from rejection and CAV. However, compared with mCyA, Tac appears to reduce the adverse effect profile for hypertriglyceridemia and renal dysfunction and the need for hypertensive medications.

Adult↗

Three-dimensional reconstruction of the equine ovary.

The equine ovary has a very unique structure in terms of its extreme large size, the presence of the ovulation fossa and the inverted location of its cortex and medulla. In the previous study, it was recognized that the application of three-dimensional internal structure microscopy (3D-ISM) to observe the mare ovary is very effective. Three-dimensional reconstruction of serially sliced images made by 3D-ISM was successful in this study with the aid of the sophisticated image processing technique. The rotation of the reconstructed ovary has been carried out with and without the application of the transparency technique in the ovarian stromal region. The spatial localization of follicles and corpus luteum was clearly visualized by rotating the reconstructed image of the ovary. The extraction of the images of follicles and corpus luteum was also available and gave a quantifiable understanding of their structure.

Animals↗

HV(MNE), a novel lymphocryptovirus related to Epstein-Barr virus, induces lymphoma in New Zealand White rabbits.

HV(MNE) is a novel Epstein-Barr (EBV)-like virus isolated from a Macaca nemestrina with CD8(+) T-cell mycosis fungoides-cutaneous T-cell lymphoma. Here it is demonstrated that intravenous inoculation of irradiated HV(MNE)-infected T cells or cell-free virus from the J94356(PBMC) cell line in New Zealand White rabbits results in seroconversion to the viral capsid antigen (VCA) of EBV; all animals that seroconverted to VCA developed malignant lymphoma within months of inoculation. In contrast, control rabbits, inoculated with heat-inactivated culture supernatants from the same cell line, failed to seroconvert to VCA and did not develop disease. Disseminated lymphoma cells of mixed origin were detected in most vital organs, including the spleen, liver, lungs, kidneys, and heart of the affected rabbits. Neoplastic infiltrates were also observed in lymph nodes, thymus, skin, and subcutaneous tissues. HV(MNE) DNA and EBV-like RNA expression was demonstrated in the lymphomatous organs and in 2 transformed T-cell lines, one established from the lymph node and the other from the blood of the 2 lymphomatous animals. Analysis of one of these T-cell lines demonstrated the persistence of HV(MNE) DNA, expression of an LMP1-like protein, and acquisition of interleukin-2 independence, and constitutive activation of the Jak/STAT pathway. Thus, HV(MNE) in rabbits provides a valuable animal model for human T-cell lymphoma whereby genetic determinants for T-cell transformation by this EBV-like animal virus can be studied.

Animals↗

In vivo evaluation of bone-bonding of titanium metal chemically treated with a hydrogen peroxide solution containing tantalum chloride.

Apatite formation on implants is important in achieving a direct bonding to bone tissue. We recently showed that titanium metal chemically treated with a hydrogen peroxide solution containing tantalum chloride has the ability to form a hydroxyapatite layer in simulated body fluid which had inorganic ion composition similar to human blood plasma. In this study, a pure titanium cylinder (4.0 mm in diameter, 20.0 mm in length) treated with this method was implanted into a hole (4.2 mm in diameter) in a rabbit's tibia. After implantation for predetermined periods up to 16 weeks, the specimens were extracted with bone tissue, and were examined by push-out test to evaluate the shearing force between the implant and bone tissue. The results were compared with those of non-treated pure titanium. Eight weeks after surgery, the shearing force of the treated titanium implanted in the 4.2 mm-hole was significantly higher than that of non-treated titanium, although the surface roughness was not changed after the treatment. Scanning electron microscopic (SEM) observation and energy-dispersive X-ray (EDX) microanalysis showed that the bone comes very close to the surface of the treated titanium. Moreover, the shearing force was higher for the implanted sample in the 4.0 mm-hole than that in the 4.2 mm-hole. Thus, it is confirmed that the treatment with hydrogen peroxide solution containing tantalum chloride provides higher bonding ability on titanium implants in vivo.

Animals↗

Increased expression of biglycan mRNA in pressure-overloaded rat heart.

Biglycan mRNA expression in rat myocardium after abdominal aortic banding with renal ischemia was examined. The Northern blot analysis demonstrated that expression of biglycan mRNA in the pressure-overloaded hearts on days 2, 7, 14 and 28 was 2.88 +/- 0.89, 2.32 +/- 0.49, 2.17 +/- 0.57 and 1.81 +/- 0.46-fold higher, respectively, than that in the sham-operated hearts. In situ hybridization showed an increased density of biglycan mRNA signal-positive cells in the pressure-overloaded hearts. The cells with positive signals were spindle-shaped mesenchymal cells in the myocardial interstitium. A marked increase in biglycan mRNA signal expression was also observed in endothelial cells and smooth muscle cells of the thickened myocardial capillary wall. These results demonstrated an increase in biglycan mRNA in the pressure-overloaded heart in mesenchymal cells in the myocardial interstitium, and in endothelial and smooth muscle cells of the capillaries, indicating that biglycan contributes to the ventricular and vascular remodeling in response to pressure overload.

Animals↗

Formation of ammonia in the reactions of a tungsten dinitrogen with ruthenium dihydrogen complexes under mild reaction conditions.

Treatment of cis-[W(N2)2(PMe2Ph)4] (5) with an equilibrium mixture of trans-[RuCl(eta 2-H2)(dppp)2]X (3) with pKa = 4.4 and [RuCl(dppp)2]X (4) [X = PF6, BF4, or OTf; dppp = 1,3-bis(diphenylphosphino)propane] containing 10 equiv of the Ru atom based on tungsten in benzene-dichloroethane at 55 degrees C for 24 h under 1 atm of H2 gave NH3 in 45-55% total yields based on tungsten, together with the formation of trans-[RuHCl(dppp)2] (6). Free NH3 in 9-16% yields was observed in the reaction mixture, and further NH3 in 36-45% yields was released after base distillation. Detailed studies on the reaction of 5 with numerous Ru(eta 2-H2) complexes showed that the yield of NH3 produced critically depended upon the pKa value of the employed Ru(eta 2-H2) complexes. When 5 was treated with 10 equiv of trans-[RuCl(eta 2-H2)(dppe)2]X (8) with pKa = 6.0 [X = PF6, BF4, or OTf; dppe = 1,2-bis(diphenylphosphino)ethane] under 1 atm of H2, NH3 was formed in higher yields (up to 79% total yield) compared with the reaction with an equilibrium mixture of 3 and 4. If the pKa value of a Ru(eta 2-H2) complex was increased up to about 10, the yield of NH3 was remarkably decreased. In these reactions, heterolytic cleavage of H2 seems to occur at the Ru center via nucleophilic attack of the coordinated N2 on the coordinated H2 where a proton (H+) is used for the protonation of the coordinated N2 and a hydride (H-) remains at the Ru atom. Treatment of 5, trans-[W(N2)2(PMePh2)4] (14), or trans-[M(N2)2(dppe)2] [M = Mo (1), W (2)] with Ru(eta 2-H2) complexes at room temperature led to isolation of intermediate hydrazido(2-) complexes such as trans-[W(OTf)(NNH2)(PMe2Ph)4]OTf (19), trans-[W(OTf)(NNH2)(PMePh2)4]OTf (20), and trans-[WX(NNH2)(dppe)2]+ [X = OTf (15), F (16)]. The molecular structure of 19 was determined by X-ray analysis. Further ruthenium-assisted protonation of hydrazido(2-) intermediates such as 19 with H2 at 55 degrees C was considered to result in the formation of NH3, concurrent with the generation of W(VI) species. All of the electrons required for the reduction of N2 are provided by the zerovalent tungsten.

Journal Article↗

Angiostatin generation by cathepsin D secreted by human prostate carcinoma cells.

Angiostatin, a potent endogenous inhibitor of angiogenesis, is generated by cancer-mediated proteolysis of plasminogen. The culture medium of human prostate carcinoma cells, when incubated with plasminogen at a variety of pH values, generated angiostatic peptides and miniplasminogen. The enzyme(s) responsible for this reaction was purified and identified as procathepsin D. The purified procathepsin D, as well as cathepsin D, generated two angiostatic peptides having the same NH(2)-terminal amino acid sequences and comprising kringles 1-4 of plasminogen in the pH range of 3.0-6.8, most strongly at pH 4.0 in vitro. This reaction required the concomitant conversion of procathepsin D to catalytically active pseudocathepsin D. The conversion of pseudocathepsin D to the mature cathepsin D was not observed by the prolonged incubation. The affinity-purified angiostatic peptides inhibited angiogenesis both in vitro and in vivo. Importantly, procathepsin D secreted by human breast carcinoma cells showed a significantly lower angiostatin-generating activity than that by human prostate carcinoma cells. Since deglycosylated procathepsin D from both prostate and breast carcinoma cells exhibited a similar low angiostatin-generating activity, this discrepancy appeared to be attributed to the difference in carbohydrate structures of procathepsin D molecules between the two cell types. The seminal vesicle fluid from patients with prostate carcinoma contained the mature cathepsin D and procathepsin D, but not pseudocathepsin D, suggesting that pseudocathepsin D is not a normal intermediate of procathepsin D processing in vivo. The present study provides evidence for the first time that cathepsin D secreted by human prostate carcinoma cells is responsible for angiostatin generation, thereby causing the prevention of tumor growth and angiogenesis-dependent growth of metastases.

Angiostatins↗

Bcl-X(L) is up-regulated by HTLV-I and HTLV-II in vitro and in ex vivo ATLL samples.

Human T lymphotropic virus type I (HTLV-I) is the etiological agent of adult T-cell lymphocytic leukemia (ATLL), whereas HTLV-II has not been associated with hematopoietic malignancies. The control of apoptotic pathways has emerged as a critical step in the development of many cancer types. As a result, the underlying mechanism of long-term survival of HTLV-I and HTLV-II was studied in infected T cells in vitro and in ex vivo ATLL samples. Results indicate that HTLV-I- and HTLV-II-infected T cells in vitro express high levels of the antiapoptotic protein Bcl compared with other human leukemic T cell lines or uninfected peripheral blood mononuclear cells. The levels of proapoptotic proteins Bax, BAD, and Bak were not significantly altered. HTLV-I and HTLV-II viral transactivators, Tax1 and Tax2, are known to increase expression of cellular genes. These proteins were tested for increased transcription from the human Bcl2 and Bcl-X(L) promoters. Whereas no effect was observed on the Bcl2 promoter, both Tax1 and Tax2 increased transcription of the Bcl-X(L) promoter in T cells, although Tax1 appeared to be more efficient than Tax2. The biological significance of these observations was validated by the finding of an increased expression of Bcl-X(L) in ex vivo ATLL cells, especially from patients unresponsive to various chemotherapy regimens. Altogether, these data suggest that overexpression of Bcl-X(L )in vivo( )may be in part responsible for the resistance of ATLL cells to chemotherapy. In addition, inefficient activation of the Bcl-X(L) promoter by Tax2 may result in a shorter survival time of HTLV-II-infected cells in vivo and a diminished risk of leukemia development.

Adult↗

p53 stabilization and functional impairment in the absence of genetic mutation or the alteration of the p14(ARF)-MDM2 loop in ex vivo and cultured adult T-cell leukemia/lymphoma cells.

Human T-cell lymphotropic virus type I (HTLV-I) transforms T cells in vitro, and the viral transactivator Tax functionally impairs the tumor suppressor p53 protein, which is also stabilized in HTLV-I-infected T cells. Thus, the functional impairment of p53 is essential to maintain the viral-induced proliferation of CD4+ mature T cells. However, in the CD4+ leukemic cells of patients with adult T-cell leukemia/lymphoma (ATLL), the viral transactivator does not appear to be expressed, and p53 mutations have been found only in a fraction of patients. We sought to investigate whether p53 function is impaired, in ex vivo samples from patients with ATLL, in the absence of genetic mutations. Here we demonstrate that the p53 protein is stabilized also in ex vivo ATLL samples (10 of 10 studied) and that at least in 2 patients p53 stabilization was not associated with genetic mutation. Furthermore, the assessment of p53 function after ionizing radiation of ATLL cells indicated an abnormal induction of the p53-responsive genes GADD45 and p21(WAF1) in 7 of 7 patients. In 2 of 2 patients, p53 regulation of cell-cycle progression appeared to be impaired as well. Because p53 is part of a regulatory loop that also involves MDM2 and p14(ARF), the status of the latter proteins was also assessed in cultured or fresh ATLL cells. The p97 MDM2 protein was not detected by Western blot analysis in established HTLV-I-infected T-cell lines or ex vivo ATLL cell lysates. However, the MDM2 protein could be easily detected after treatment of cells with the specific proteasome inhibitor lactacystin, suggesting a normal regulation of the p53-MDM2 regulating loop. Similarly, p14(ARF) did not appear to be aberrantly expressed in ex vivo ATLL cells nor in any of the established HTLV-I-infected T-cell lines studied. Thus, p53 stabilization in HTLV-I infection occurs in the absence of genetic mutation and alteration of the physiologic degradation pathway of p53. (Blood. 2000;95:3939-3944)

Adult↗

The influence of conventional and cross-reactive group HLA matching on cardiac transplant outcome: an analysis from the United Network of Organ Sharing Scientific Registry.

BACKGROUND: The short tolerable cold ischemia time and the importance of other risk factors have generally superseded the role of HLA matching in the allocation of donor hearts. Recent advances in the accuracy and time required to perform HLA typing and crossmatching, however, have led us to re-examine the United Network of Organ Sharing Transplant Registry for the effects of the HLA incompatibility on outcome in relation to other possible risk factors. METHODS: These include conventional HLA-A, -B, and cross-reactive group (CREG) mismatching (mm), HLA-DR mm, pretransplantation panel-reactive antibody (PRA), recipient and donor race and donor age, cold ischemia time, and the pretransplantation use of either a left ventricular assist device or an intra-aortic balloon pump. RESULTS: Three-year survival was clearly inferior in non-white (0.6921) as compared with white (0.7632) recipients, but this difference could not be accounted for by the degree of donor-recipient HLA mm that had occurred by chance. Nevertheless, the degree of mm that did occur seemed to have an impact on survival. The importance of HLA-DR mm was confirmed, and it ranked only behind the use of an assist device and recipient race in the multivariate analysis. HLA-A and B mm exerted an additional effect, but this was only true in white recipients. Of these, HLA-A achieved statistical significance as an independent risk factor. In general, CREG mm was not a significant variable. However, more than twice as many 0-1 or 0-2 CREG, 0 DR mm as compared with 0-1 or 0-2 A,B, 0 DR mm transplants enjoyed approximately equal and very good 1- and 3-year survival. Assuming no change is cold ischemia time, the potential number of 0 CREG, 0 DR mm, ABO-compatible transplants that could be achieved when an Organ Procurement Organization had 50-100 patients on their waiting list was calculated. The surprisingly high frequency of approximately 24-36% suggests that this favorable match could be considered along with other important factors in the local allocation process. When pretransplantation PRA was analyzed as a continuous variable from 0 to 100%, it was a highly significant risk factor, but this effect was more strikingly evident when the PRA was analyzed in 20% increments above zero. Recently, left ventricular assist device usage has become increasingly common, and it has been associated with strikingly increased pretransplantation PRA levels. When they occur together, the data indicates that these patients are at a very high risk for graft failure. CONCLUSIONS: We believe that newer typing and crossmatching techniques make it possible to add HLA criteria to the allocation protocol of donor cardiac organs and would lead to improved long-term survival.

Chi-Square Distribution↗

Deletion of the p16INK4A gene in ex vivo acute adult T cell lymphoma/leukemia cells and methylation of the p16INK4A promoter in HTLV type I-infected T cell lines.

The stoichiometry of the p16INK4A and p15INK4B proteins bound to the cyclin D-CDK4/6 complex regulates the entry of cells into the G1 phase of the cell cycle. Thus, their level of expression is essential in maintaining regulated cell growth. In several tumors, deletion of these genes has been reported and, more recently, promoter methylation has been suggested as an alternative mechanism to decrease the expression of these cell cycle inhibitor proteins. Here, we studied the methylation status and the integrity of the p16INK4A and p15INK4B genes in 8 chronically HTLV-I-infected T cell lines and in ex vivo cells from 14 ATLL patients. Deletion of the locus carrying both genes was not found in the HTLV-I-infected T cell lines but was found in seven of eight acute ATLL cases and in none of the PBMCs from the chronic cases or the affected lymph nodes of the lymphoma type. In contrast, partial or complete methylation of one or both genes was found only in chronically HTLV-I T cells. Thus, HTLV-I infection targets the p16INK4A and p15INK4B loci both in vitro and in vivo, although the mechanisms may differ.

Cell Line, Transformed↗

Effectiveness of an organ-sharing program in providing zero HLA-A,B,DR mismatched kidneys for transplantation in Taiwan.

PURPOSE: This study evaluated the effects of organ sharing on the allocation of kidneys from cadaveric donors to uremic patients from National Cheng Kung University Hospital (CKUH) and National Taiwan University Hospital (NTUH) who were waiting for kidney transplantation. METHODS: Standard complement-dependent microcytotoxicity assays were used. Human leukocyte antigen (HLA)-A,B,C typing was performed on nylon-wool-enriched T lymphocytes. HLA-DR typing was performed on either nylon-wool-separated B cells or Dynabeads. Isolation of class II-positive cells was performed with commercial typing trays. RESULTS: Organs were allocated from a total of 88 cadaveric donors to 320 patients treated at CKUH and 179 patients treated at NTUH. Cadaveric kidneys could be allocated with an A,B,DR mismatch to 6.9% of CKUH patients and to 4.7% of NTUH patients. When CKUH and NTUH patients were pooled, the total number of kidneys that could be allocated with 0-A,B,DR mismatch increased to 13.3% (p < 0.004). However, when allocation was assessed using 10,000 potential bone marrow donors instead of the 88 cadaveric donors, kidneys could have been allocated with 0-A,B,DR mismatch to 12% (p = 0.64) of patients. No significant benefit was found when allocation estimates from the 10,000 potential bone marrow donors were compared with those for the 88 cadaveric donors. Use of epitope matching resulted in a 0-A,B cross-reactive epitope group, and a 0-DR mismatch allocation rate of 36.4% in CKUH patients and 31.8% in NTUH patients. This rate increased to 54.6% (p < 0.001) when the patients from these hospitals were pooled. CONCLUSION: The results of this study demonstrate that the pooling of patients among regional transplant centers in Taiwan can significantly enhance the benefits of an organ donation program through better HLA matching.

HLA-A Antigens↗

A novel Epstein-Barr virus-like virus, HV(MNE), in a Macaca nemestrina with mycosis fungoides.

Epstein-Barr virus (EBV) infection of humans has been associated with the development of lymphoid malignancies mainly of B-cell lineage, although occasionally T-cell lymphomas have been reported. We describe here the characterization of a novel EBV-like virus (HV(MNE)) isolated from a simian T-cell lymphotropic virus type I/II (STLV-I/II) seronegative pigtailed macaque (Macaca nemestrina) with a cutaneous T-cell lymphoma. Immunohistochemistry studies on the skin lesions demonstrated that the infiltrating cells were of the CD3(+)/CD8(+) phenotype. Two primary transformed CD8(+) T-cell lines were obtained from cultures of peripheral blood mononuclear cells (PBMC) and skin, and, with time, both cell lines became interleukin-2-independent and acquired the constitutive activation of STAT proteins. Polymerase chain reaction analysis of the DNA from the cell lines and tissues from the lymphomatous animal demonstrated the presence of a 536-bp DNA fragment that was 90% identical to EBV polymerase gene sequences, whereas the same DNA was consistently negative for STLV-I/II sequences. Electron microscopy performed on both cell lines, after sodium butyrate treatment, showed the presence of a herpes-like virus that was designated HV(MNE) according to the existing nomenclature. In situ hybridization studies using EBV Epstein-Barr viral-encoded RNA probes showed viral RNA expression in both CD8(+) T-cell lines as well as in the infiltrating CD8(+) T cells of skin-tissue biopsies. Phylogenetic analysis of a 465-bp fragment from the polymerase gene of HV(MNE) placed this virus within the Lymphocryptovirus genus and demonstrated that HV(MNE) is a distinct virus, clearly related to human EBV and other EBV-like herpesviruses found in nonhuman primates.

Animals↗

A lysine-to-arginine change found in natural alleles of the human T-cell lymphotropic/leukemia virus type 1 p12(I) protein greatly influences its stability.

The HTLV-1 singly spliced open reading frame I protein, p12(I), is highly unstable and appears to be necessary for persistent infection in rabbits. Here we demonstrate that p12(I) forms dimers through two putative leucine zipper domains and that its stability is augmented by specific proteasome inhibitors. p12(I) is ubiquitylated, and mutations of its unique carboxy-terminus lysine residue to an arginine greatly enhance its stability. Interestingly, analysis of 53 independent HTLV-1 strains revealed that the natural p12(I) alleles found in ex vivo samples of tropical spastic paraparesis-HTLV-1-associated myelopathy patients contain a Lys at position 88 in some cases, whereas arginine is consistently found at position 88 in HTLV-1 strains from all adult T-cell leukemia-lymphoma (ATLL) cases and healthy carriers studied. This apparent segregation of different alleles in tropical spastic paraparesis-HTLV-associated myelopathy and ATLL or healthy carriers may be relevant in vivo, since p12(I) binds the interleukin-2 receptor beta and gammac chains, raising the possibility that the two natural alleles might affect differently the regulation of these molecules.

Adult↗

A kinetic analysis of the interaction of human recombinant tissue factor pathway inhibitor with factor Xa utilizing and immunoassay and the effect of antithrombin III/heparin on the complex formation.

We have recently shown that a complex formation of tissue factor pathway inhibitor (TFPI) and factor Xa (Xa) promotes a clearance of proteoglycans-associated TFPI. In the current studies, the interaction between human recombinant TFPI (h-rTFPI) and Xa were kinetically analyzed by utilizing both a protease inhibitor, p-(amidophenyl) methanesulfonyl fluoride hydrochloride, and a specific enzyme-linked immunosorbent assay for the complex of h-rTFPI with Xa. We further investigated the effect of antithrombin III on the complex formation between h-rTFPI and Xa. We found that the h-rTFPI/Xa complex formed in a time-dependent manner: the second-order rate constant (K1) for the complex formation was calculated to be 0.86x10(6) M(-1)s(-1). The addition of antithrombin III to the h-rTFPI solution modestly reduced the rate of the complex formation between h-rTFPI and Xa. Heparin strikingly enhanced antithrombin III's inhibition of Xa and resulted in complete abrogation of the complex formation between h-rTFPI and Xa in the absence or presence of acidic phospholipids. Furthermore, antithrombin III induced dissociation of the preformed h-rTFPI/Xa complex in the presence of heparin. These results suggest that in the presence of heparin, antithrombin III interferes with the catabolism of TFPI mediated via Xa.

Antithrombin III↗