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T Tamiya

Publications and source records attributed to T Tamiya.

At least 73 records · Page 4Linked to original sources
PubMed1996

Malignant astrocytomas with homozygous CDKN2/p16 gene deletions have higher Ki-67 proliferation indices.

p16 is involved in a cell-cycle regulatory cascade that includes cyclin-dependent kinase 4 (cdk4), cyclin D1 and pRb. Alterations of each of these components have been described in primary human glioblastoma multiforme (GBM) or GBM cell lines, and alterations of the individual components of this pathway appear inversely correlated with one another. While this suggests that disruption of any individual component has similar oncogenic effects, homozygous deletions of the CDKN2/p16 gene are the most common genetic alteration. We investigated the relationship between homozygous CDKN2/ p16 deletions and cellular proliferation in 50 primary astrocytomas (2 WHO grade I pilocytic astrocytoma, 15 grade II astrocytomas, 20 grade III anaplastic astrocytomas and 13 grade IV GBMs). Using a comparative multiplex PCR assay, homozygous deletions of the CDKN2/p16 gene were detected in 5 anaplastic astrocytomas (25%) and 6 GBMs (46%), but in none of the lower-grade tumors. Ki-67 immunohistochemistry was used to assess the number of proliferating cells in the same samples used for molecular genetic analysis. In both anaplastic astrocytomas and GBMs, Ki-67 proliferation indices were significantly higher in tumors with CDKN2/p16 deletions (20%) than in those without deletions (10%; p = 0.0001). These results suggest that homozygous CDKN2/p16 deletions in high-grade astrocytomas may have a more deleterious effect on cell cycle control than the other aberrations in the p16-cdk4-cyclin D1-pRb pathway, and may provide one explanation for why homozygous CDKN2/p16 deletions are more common genetic events in high-grade astrocytomas than RB mutations or CDK4 amplification.

Adult↗
PubMed1995

Enhancement of interleukin-4-mediated tumor regression in athymic mice by in situ retroviral gene transfer.

Intratumoral grafting of genetically engineered cells that produce interleukin-4 (IL-4) has been shown to produce tumor regression as well as prolong survival of mice harboring intracerebral gliomas. We sought to determine whether retroviral-mediated gene delivery into tumor cells in situ resulted in enhanced tumor regression by IL-4. Two mouse fibroblast lines were obtained: they both secreted similar levels of IL-4 but one produced a retrovirus vector bearing the IL-4 gene (CRE-MFG-IL-4 cells), whereas the other did not (NIH3T3-IL-4 cells). In mixed transplantation assays in the subcutaneous flanks of athymic mice, CRE-MFG, IL-4 cells were more effective than NIH3T3-IL-4 cells in inhibiting the growth of rat C6 glioma cells (p < 0.005, ANOVA). Subcutaneous tumors injected with fibroblasts that produced a control retrovirus vector without producing IL-4 (CRE-MFG-LacZ cells) did not inhibit subcutaneous tumor growth. An intracranial assay was used to evaluate survival of athymic mice harboring intracranial gliomas. Three days after implanting rat C6 glioma cells into the right frontal lobes of athymic mice, NIH3T3-IL-4 cells (n = 10) or CRE-MFG-IL-4 cells (n = 10) were stereotactically inoculated into the tumor bed. The average survival of mice treated with CRE-MFG-IL-4 cells was 38 days (+/- 2.4, SE), whereas that of mice treated with NIH3T3-IL-4 cells was 31 days (+/- 0.8, SE) (p < 0.005, ANOVA; p < 0.001, log-rank analysis).(ABSTRACT TRUNCATED AT 250 WORDS)

3T3 Cells↗
PubMed1995

Transgene inheritance and retroviral infection contribute to the efficiency of gene expression in solid tumors inoculated with retroviral vector producer cells.

One strategy to achieve efficient gene delivery into brain tumors employs the stereotactic implantation of fibroblasts that express a foreign gene and produce a retroviral vector bearing that gene. Another method involves the grafting of fibroblasts genetically engineered to produce a foreign gene product of interest. It is not clear to what extent retrovirus production in vivo provides an advantage over the grafting of genetically engineered cells for the purpose of achieving transgene expression. These two methods of gene delivery were compared in vivo by using the following cell lines: CRIP-MFG-LacZ cells, which express the lacZ gene and produce retrovirus vectors that bear this gene, and CRIP-LacZ cells, which express the lacZ gene, but do not produce retrovirus. Gene delivery was assessed in C6 gliomas established in the righ frontal lobe of athymic mice. CRIP-MFG-LacZ or CRIP-LacZ cells were inoculated stereotactically into these tumors. When CRIP-MFG-LacZ cells were used, a relatively elevated level of lacZ gene expression was present in cells scattered throughout the tumor. Using a computerized imaging system, this expression occurred in approximately 10% of the tumor area at 1 week, 42% at 2 weeks, and 32% at 3 weeks. In contrast, with CRIP-LacZ cells, lacZ gene expression was much weaker and occurred in a more focal area within the tumor. This expression occupied approximately 5% of the tumor area at 1 and 2 weeks and had almost disappeared at 3 weeks. In both cases there was no notable expression of the transgene in normal brain cells. In conclusion, transgene expression in brain tumors was achieved in more cells, at higher levels, and for longer time periods with retroviral vector-producing cells than with genetically engineered fibroblasts. This efficiency of gene delivery likely results from direct in situ delivery of the transgene to tumor cells with subsequent inheritance of the reporter gene to progeny tumor cells.

3T3 Cells↗
PubMed1995

Diffusible cytotoxic metabolites contribute to the in vitro bystander effect associated with the cyclophosphamide/cytochrome P450 2B1 cancer gene therapy paradigm.

Tumor cells become sensitive to the inert prodrug cyclophosphamide (CPA) after transfer of the gene encoding cytochrome P450 2B1. This enzyme activates CPA into 4-hydroxycyclophosphamide, which ultimately degrades into acrolein and phosphoramide mustard, the anticancer and DNA-alkylating metabolite. It is imperative that any prodrug-activating gene therapy strategy against cancer possess the capacity to affect the proliferation of tumor cells even when they do not express the transgene (bystander effect), because current methodologies cannot achieve gene transduction in all tumor cells. Prodrug-activating gene therapy schemes described to date exhibit a bystander effect that is not mediated by conditioned medium in culture and may depend on cell contact. In contrast, we find that CPA-sensitized, P450-expressing C6 glioma cells (C6-P450) transfer cytotoxicity to nonexpressing cells by releasing diffusible metabolites through the medium. A 3-h exposure to the prodrug is necessary and sufficient to achieve killing of the transfected cells, and medium conditioned by these cells can kill untransfected cells with similar potency. This bystander effect occurs in the presence of CPA even when only 10% of cells in culture express the P450 2B1 gene, and it is not reproduced by cells that have been irradiated. In an animal model of intracerebral brain tumors, expression of the P450 2B1 gene within the neoplastic cells enhanced significantly the antitumor effect of CPA, even when it was administered systemically. This study shows that CPA/P450 2B1 gene therapy represents a novel tumor-killing strategy that displays an expanded range of cytotoxic action both spatially and temporally within tumor cells and significantly potentiates the anticancer action of CPA when administered i.v.

Animals↗
PubMed1994

Gene transfer into experimental brain tumors mediated by adenovirus, herpes simplex virus, and retrovirus vectors.

Three vectors derived from retrovirus, herpes simplex virus type 1 (HSV), and adenovirus were compared in cultured rat 9L gliosarcoma cells for gene transfer efficiency and in a 9L rat brain tumor model for histologic pattern and distribution of foreign gene delivery, as well as for associated tumor necrosis and inflammation. At a multiplicity of infection of 1, in vitro transfer of a foreign gene (lacZ from Escherichia coli) into cells was more efficient with either the replication-defective retrovirus vector or the replication-conditional thymidine kinase (TK)-deficient HSV vector than with the replication-defective adenovirus vector. In vivo, stereotactic injections of each vector into rat brain tumors revealed three main histopathologic findings: (i) retrovirus and HSV vector-mediated gene transfer was relatively selective for cells within the tumor, whereas adenovirus vector-mediated gene transfer occurred into several types of endogenous neural cells, as well as into cells within the tumor; (ii) gene transfer to multiple infiltrating tumor deposits without apparent gene transfer to intervening normal brain tissue occurred uniquely in one animal inoculated with the HSV vector, and (iii) extensive necrosis and selective inflammation in the tumor were evident with the HSV vector, whereas there was minimal evidence of tumor necrosis and inflammation with either the retrovirus or adenovirus vectors.

Adenoviruses, Human↗
PubMed1994

Experimental tumor therapy in mice using the cyclophosphamide-activating cytochrome P450 2B1 gene.

Most malignant tumors of the central nervous system do not respond well to chemotherapy. The anticancer drug cyclophosphamide (CPA) is largely ineffective against these neoplasms as its conversion to DNA-alkylating, cytotoxic metabolites is restricted primarily to the liver and these metabolites do not readily cross the blood-brain barrier. Here, we show that brain tumor cells can be sensitized to the cytotoxic effects of CPA, both in culture and in vivo, by introduction of the hepatic enzyme responsible for the activation of CPA, cytochrome P450 2B1. Stable transfection of rat C6 glioma cells with the P450 2B1 gene rendered the cultured tumor cells sensitive to CPA. Further, C6 cells bearing this gene were more sensitive than parental cells to the cytotoxic action of CPA when grown subcutaneously in the flanks of athymic mice. Murine fibroblasts producing a retrovirus vector encoding P450 2B1 and expressing this enzyme were then prepared and grafted into the brains of athymic mice seeded with rat C6 gliomas. Intrathecal administration of CPA prevented the development of meningeal neoplasia and led to partial regression of the parenchymal tumor mass. By contrast, C6 glioma-bearing mice receiving fibroblasts expressing the Escherichia coli lacZ gene and CPA exhibited extensive meningeal tumors and parenchymal solid brain tumors. The in situ activation of CPA by cytochrome P450 2B1 provides a novel approach not only for brain tumor gene therapy, but also for negative, drug-conditional selection of other defined cell populations.

Animals↗
PubMed1993

Prognostic significance of human papillomavirus genomes (type-16, -18) and aberrant expression of p53 protein in human esophageal cancer.

The presence and distribution of human papillomavirus (HPV) DNA or of increased expression of the p53 protein were determined in 71 patients with esophageal squamous-cell carcinoma (SCC) by in situ hybridization with biotinylated DNA probes for HPV-16, -18, -31 and -33, and immunohistochemical techniques using antibody to p53 protein. Of 71 patients from Kochi prefecture, 24 (Group I) were positive for HPV DNA, including 10 for HPV type-16 and 14 for HPV type-18; in contrast, none were positive for HPV-31 or -33. Of the remaining 47 patients, 24 (Group II) showed positive nuclear staining in cancer cells with p53 antibody. The group of 23 patients with neither HPV nor p53 expression (Group III) had a significantly better survival rate than Group I or II. These results suggest that HPV-16 and -18 may play a role in the pathogenesis of esophageal SCC, particularly with regard to its striking geographical distribution; that esophageal cancers do occur in the absence of HPV infection when over-expression of p53 is present; and that the presence of HPV infection and over-expression of p53 may each be a factor indicating a relatively poor prognosis.

Adult↗
PubMed1993

Purification and characterization of two metalloproteinases from squid mantle muscle, myosinase I and myosinase II.

Metalloproteinases, myosinase I and myosinase II, that hydrolyze the heavy chain of myosin, were purified from squid mantle muscle. Myosinase I does not hydrolyze other muscle proteins, casein, haemoglobin, or MCA-substrates, while II hydrolyzes tropomyosin. Both myosinase I and myosinase II gave a single protein band on SDS-PAGE with a molecular mass of 16 and 20 kDa, respectively. Their activities were inhibited by EDTA and 1,10-phenanthroline, and II was also inhibited by EGTA. They could be reactivated with some divalent cations, I was especially reactivated with Co2+ and II especially with Zn2+. The optimum pH of both activities was 7.0; the optimum temperature for both was 40 degrees C. Myosinase I hydrolyzes myosin heavy chains to produce 130 and 90 kDa fragments. The N-terminal amino-acid sequence of the 90 kDa fragment indicates that myosinase I splits the myosin heavy chain between Ala-1161 and Thr-1162 in subfragment 2. Myosinase II hydrolyzes myosin heavy chain to produce 158 and 65 kDa fragments, and it splits between Glu-1381 and Thr-1382 in LMM. Myosinases I and II are most likely related to the metabolism of myosin in vivo.

Amino Acid Sequence↗
PubMed1993

Morphological aspects of Achacin-treated bacteria.

1. The morphology of bacteria treated with the bactericidal glycoprotein, Achacin, purified from the giant African snail, Achatina fulica Férussac, has been studied. 2. Achacin lengthens the bodies of Escherichia coli by three to seven times. 3. Achacin damages the surface of Staphylococcus aureus and sinks the cytoplasmic membranes into the cytoplasm. 4. Achacin causes neither the leakage nor the destruction of cells.

Escherichia coli↗
PubMed1993

Prognostic significance of simultaneous infiltration of HLA-DR-positive dendritic cells and tumor infiltrating lymphocytes into human esophageal carcinoma.

The distribution of HLA-DR-positive dendritic cells (DR+DCs) and tumor infiltrating lymphocytes (TILs) was investigated in 67 patients with squamous cell carcinoma of the esophagus. DR+DCs were chiefly present among the cancer cell nests, and few were seen in the stroma. As clusters, UCHL-1-positive T-cells (UCHL1-Ts) were detected in the tissue around the cancer cell nests and as individual cells within tumor nests. Some UCHL1-Ts in the tumor nests showed direct contact with DR+DCs. In addition, a few OPD4-positive helper/inducer T cells were found among cancer cells, and were densely present in the stroma. A correlation was demonstrated between the number of DR+DCs and UCHL1-Ts in each patient (R = 0.4547, p < 0.01). In addition, dense tumor infiltration by both DR+DCs and UCHL1-Ts within the cancer cell nests was related to a better prognosis (p < 0.01).

Adult↗
PubMed1993

[A case report: mitral valve replacement for the patient with essential thrombocythemia].

A 62-year-old man with heart murmur and recent cerebral thrombosis was admitted to our hospital. Examination of his heart revealed mitral stenosis and hematological study confirmed the diagnosis of essential thrombocytosis (ET). After 1100 ml pre-operative phlebotomy, mitral valve replacement with a 29 mm Björk-Shiley prosthesis was performed utilizing routine cardio-pulmonary bypass using only his prestored blood and moderate hypothermia. We had no difficulty in hemostasis at the operation. Acute gastric bleeding began suddenly as much as 1500 ml on the 4th postoperative day. As medical care was in vain, emergent distal gastrectomy was performed. As we used urokinase for fear of thrombosed valve formation, residual gastric bleeding was continued on. Then, we began to use Gabexate-Mesilate (FOY) instead of urokinase. Retrospectively, Gabexate-Mesilate was very useful drug for preventing the left atrium and prosthesis from thrombo-formation until the start of oral intake of Warfarin and Busulfan. To our knowledge, this would be the first case report of open-heart valve replacement surgery in a ET patient in Japan.

Gabexate↗
PubMed1992

Molecular cloning of the antibacterial protein of the giant African snail, Achatina fulica Férussac.

An expression cDNA library was constructed with poly(A)-rich RNA extracted from the collar of the giant African snail, Achatina fulica Férussac. A 1.9-kbp cDNA clone encoding a precursor of antibacterial glycoprotein of the snail, achacin, was isolated from the cDNA expression library. The cDNA sequence contains an open reading frame with 1593-nucleotide residues. The deduced amino acid sequence of this achacin precursor starts with a 29-residue leader peptide followed by a 502-residue mature peptide (56 kDa) with four possible N-glycosylation sites, Asn-Xaa-Ser or Asn-Xaa-Thr. The Northern-blot analysis proved that the achacin precursor was specifically expressed in the tissue of snail collar and processed to mature achacin. cDNA inserts encoding achacin precursor were subcloned into expression plasmids. Three kinds of expressed polypeptides were cross-reacted with rabbit antiserum raised against achacin. The largest polypeptide (M(r) 63,000) should be the achacin precursor.

Amino Acid Sequence↗
PubMed1992

Electrophysiologic study of dysrhythmias after atrial operations in dogs.

Experiments were conducted with 159 dogs to investigate the mechanism of persistent dysrhythmias clinically encountered after atrial-level operations. Those found after incisions to the internodal pathways (INPs) of the right atrium were analyzed using cardiac mapping in an anesthetized or extracorporeally perfused state. Longitudinal incisions of the posterior INP often allowed inducible sustained atrial flutter, with circus movement of excitation around the right atrium near the tricuspid orfice. Sustained atrial flutter thus produced was modified in cycle length by coexisting division of the middle INP but inhibited by that of the anterior INP. Its incidence increased at chronic stage, with marked cicatricial changes. The disrupted anterior INP markedly prolonged conduction time to the atrioventricular node and A-H interval compared with the other disruptions. Persistent atrioventricular junctional rhythm developed in about 50% of the animals after disruption of all three INPs or anterior and posterior INPs; division of the anterior INP was the common potent factor, although no single blocked INP produced persistent junctional rhythm. Our results support the "summation theory." The incidence of junctional rhythm and hypoxia of the sinoatrial node (flow rate of less than 10 mL.100 g-1.min-1) were markedly enhanced by coexisting blockade of atrial feeding arteries in addition to division of the anterior INP. In conclusion, massive posterior INP disruption is a potent anatomic substrate in producing sustained atrial flutter, middle INP division a modifier, and anterior INP division an inhibitor. Division of the anterior INP is a potent anatomic substrate in producing junctional rhythm, and hypoxia involving the sinoatrial node reacts as its synergic factor.

Animals↗
PubMed1992

Bactericidal action of a glycoprotein from the body surface mucus of giant African snail.

1. Bactericidal action of a glycoprotein, Achacin, purified from the giant African snail, Achatina fulica Férussac, has been studied. 2. Achacin kills both gram-positive and gram-negative bacteria, but only in their growing states. 3. Achacin does not have any bacteriolytic activity. 4. The strain which has no cell wall is a little more sensitive than the native strain and the cell membrane-damaged strain. 5. Achacin was observed on the cytoplasmic membrane and on the cell wall of treated Escherichia coli by immunoelectron microscopy. 6. Achacin attacks the cytoplasmic membrane of the cell.

Animals↗