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Biomedical subjects

S Tsunoda

Publications and source records attributed to S Tsunoda.

At least 73 records · Page 4Linked to original sources
PubMed1998

Antitumor activity of tumor necrosis factor alpha conjugated with divinyl ether and maleic anhydride copolymer on solid tumors in mice.

The purpose of this study is to further explore the usefulness of conjugation with functional polymeric modifiers for clinical application of bioactive proteins and to increase the therapeutic efficacy of tumor necrosis factor alpha (TNF-alpha) by conjugation in vivo. We synthesized TNF-alpha conjugated with the copolymer of divinyl ether and maleic anhydride (DIVEMA), which has intrinsic antitumor activity as a synthetic biological response modifier. The synthesis of DIVEMA-TNF-alpha could be controlled by the addition of 2,3-dimethylmaleic anhydride (DMMAn), which binds to or separates from amino groups when the pH is changed. The specific activity of DIVEMA-TNF-alpha (+) synthesized with DMMAn was hardly decreased in vitro. However, DIVEMA-TNF-alpha (-), which is conjugated without blocking by DMMAn, had a markedly diminished specific activity. DIVEMA-TNF-alpha (+) caused a dramatic hemorrhagic necrotic effect on the tumor when compared to native TNF-alpha 24 h after i.v. injection into mice bearing Sarcoma-180 solid tumors. In addition, DIVEMA-TNF-alpha (+) at a dose of only 100 Japan reference units per mouse revealed a dramatic antitumor effect that is approximately 100 times greater than native TNF-alpha and that could induce complete regression in all five mice bearing Meth-A solid tumors without any apparent side effects. Because neither DIVEMA alone nor a mixture of TNF-alpha and DIVEMA caused antitumor activity with i.v. administration, the increase in antitumor potency of TNF-alpha may be caused by the covalent conjugation with DIVEMA. DIVEMA-TNF-alpha at low dose revealed dramatic antitumor potency. Because TNF-alpha injected in vivo is extremely low-dose, concentration of intrinsic TNF-alpha in vivo is not influenced. Therefore, the cytokine network in vivo is not destroyed. These results suggest that DIVEMA is a useful polymeric modifier for conjugation of TNF-alpha to increase its antitumor activity.

Animals↗
PubMed1998

Frequent alterations of cell-cycle regulators in astrocytic tumors as detected by molecular genetic and immunohistochemical analyses.

Alterations of CDKN2A, RB, and cyclin D1 genes and expression of their products in astrocytic tumors were studied using a combination of molecular genetic and immunohistochemical assays. In addition, the association of gene status with clinical outcome was evaluated. Alterations of CDKN2A and RB gene in 30 lesions were analyzed by single-strand conformation polymorphism of polymerase chain reaction (PCR-SSCP), direct sequencing, and Western blotting. Methylation of the CDKN2A promoter was detected by methylation-specific PCR. Immunohistochemistry was applied to determine the expression of gene products in tumors from 94 patients for whom clinical outcome was also evaluated. Analyses of the CDKN2A gene revealed 12 homozygous or hemizygous deletions, one mutation in exon 1, and three methylations in the promoter. Expression of p 16 protein was not detected in 18 of 30 cases. RB mutations leading to loss of expression of the pRb were found in four (13%) cases, and six were immunohistochemically negative for this protein. Overexpression of cyclin D1 was obtained in 51 (54%) of 94 cases. Patients with pRb-negative tumors had a significantly greater risk of earlier death than those with p16 and cyclin D1 alterations, Both p16 and pRb immunohistochemistry provides useful complementary information and may provide valuable predictive information in screening. The biological consequences of deregulating individual components along cell control pathways are unequal, perhaps reflecting their hierarchical roles in the G1 checkpoint.

Adolescent↗
PubMed1998

Genetic variations in recurrent astrocytic tumors detected by restriction landmark genomic scanning.

The genetic mechanisms associated with recurrence of advanced astrocytic tumors are poorly understood. We therefore analyzed 24 biopsy specimens from 12 patients with a recurrent astrocytic tumor by a two-dimensional gel electrophoresis method, termed restriction landmark genomic scanning (RLGS). Four spot changes were commonly present in the primary astrocytomas, indicating that the corresponding gene alterations were early events in the development of this tumor type. Altered spots were more frequent and of different distribution in recurrent tumors than in the primary astrocytomas. In particular, specifically increased intensity for spots on chromosomes 9-12 and 18 were observed in the secondary tumors, suggesting a relation with recurrence. The same spot changes observed in primary tumors were also found in the respective secondary lesions but with strikingly different densities in some cases, suggesting increased genetic instability. The altered segments provide important candidate regions for the search for genes involved in events leading to progression and more malignant recurrent tumors.

Astrocytoma↗
PubMed1998

In vitro schedule-dependent interaction between paclitaxel and SN-38 (the active metabolite of irinotecan) in human carcinoma cell lines.

Paclitaxel and irinotecan are important new anticancer agents. The combination of these two agents has been considered for use against a variety of advanced solid tumors. Since the schedule-dependent effects of this combination may be crucial to its use, we studied the interaction of paclitaxel and SN-38 (the active metabolite of irinotecan) in various schedules in four human cancer cell lines in culture. Cell growth inhibition after 5 days was determined using an MTT assay. The effects of drug combinations at the IC80 level were analyzed by the isobologram method. Simultaneous exposure to paclitaxel and SN-38 for 24 h produced antagonistic (subadditive and protective) effects in the human lung cancer cell line A549, the breast cancer cell line MCF7, and the colon cancer cell line WiDr, and produced additive effects in the ovarian cancer cell line PA1. Sequential exposure to paclitaxel for 24 h followed by SN-38 for 24 h, and the reverse sequence, produced additive effects in all four cell lines. These findings suggest that sequential administration, not simultaneous administration, may be the appropriate schedule for the therapeutic combination of paclitaxel and irinotecan. Continued preclinical and clinical studies should provide further insights and assist in determining the optimal schedule for this combination in clinical use.

Antineoplastic Agents, Phytogenic↗
PubMed1998

Sleep apnoea in well-controlled myasthenia gravis and the effect of thymectomy.

We conducted overnight polysomnographic sleep studies of 16 patients (5 men and 11 women) with clinically well-controlled myasthenia gravis (MG). The subtypes of MG were IIA (3 patients), IIB (11 patients), IV (1 patient) and V (1 patient). Twelve patients were found on polysomnography to have obstructive and/or central types of the sleep apnoeas (SA). Their mean age was 42.4, SD 16.4 years, and the mean duration of MG was 7.4, SD 6.96 years. SA was not detected in 4 patients whose mean age was 30.8, SD 10.71 years and who had manifested MG for a mean duration of only 0.9, SD 0.65 years. Thus, patients with a longer duration of MG tended to have more SA. In 9 of the 12 SA patients, polysomnographic studies were repeated following thymectomy. SA had resolved in 6 patients, but persisted in 3. These findings suggest that SA is a possible clinical manifestiation of MG and that nocturnal dysfunction of both peripheral and central colinergic systems may be involved.

Adult↗
PubMed1998

Specificity in signaling pathways: assembly into multimolecular signaling complexes.

A critical issue in the field of signal transduction is how signaling molecules are organized into different pathways within the same cell. The importance of assembling signaling molecules into architecturally defined complexes is emerging as an essential cellular strategy to ensure specificity and selectivity of signaling. Scaffold proteins function as the pillars of these transduction complexes, bringing together a diversity of signaling components into defined ultramicrodomains of signaling.

Animals↗
PubMed1998

Drug resistance and apoptosis in ENU-induced rat brain tumors treated with anti-cancer drugs.

To cast light on the mechanisms of drug-resistance, experimental brain tumors were immunohistochemically evaluated for expression of glutathione S-transferase (GST)-alpha, mu, pi, p-glycoprotein and apoptosis-related factors, such as bcl-2 and p53, as well as by the terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labelling (TUNEL) method. Rat brain tumors induced by means of prenatal exposure to ethylnitrosourea (ENU) were treated with 1-(4-amino-2-methyl-5-pyrimidinyl)methyl-3-(2-chloroethyl)-3-nitrosourea hydrochloride (ACNU) and/or vincristine. Tumors more than 2 mm in size were considered to be drug resistant. The expression of GST-mu was strongly positive in ACNU-treated brain tumors, while p-glycoprotein was overexpressed in vincristine-treated brain tumors. Neither p53 nor bcl-2 expression directly correlated with apoptosis identified by TUNEL method, but tumors lacking apoptotic cells always demonstrated the expression of either GST-mu or p-glycoprotein. These results indicate that tumors resistant to chemotherapy might not be susceptible to induction of apoptosis, and therefore that mechanisms of drug resistance are related to programmed cell death in brain tumors.

Animals↗
PubMed1998

Bone marrow involvement in lymphoma: the importance of marrow magnetic resonance imaging.

Detection of bone marrow involvement is important for staging and treatment decisions in patients with lymphoma. Although routine bone marrow evaluation is based on aspirates and bone marrow biopsies, new diagnostic tools are required to improve diagnostic accuracy. Visual and quantitative assessment of the bone marrow by magnetic resonance (MR) imaging is useful for the detection of occult lymphomatous marrow involvement. MRI is also suitable for the evaluation of disease extent in the bone marrow. Furthermore, abnormal images on marrow MRI may be associated with a significantly poorer survival in patients with lymphoma, regardless of histologic findings in the marrow. Evaluation of the bone marrow by MRI is essential to assess disease status in patients with lymphoma.

Biopsy↗
PubMed1998

Schedule-dependent synergism and antagonism between paclitaxel and methotrexate in human carcinoma cell lines.

Paclitaxel and methotrexate are active against a variety of solid tumors. Because of differences in their mechanisms of action and toxicity profiles, the combination of these two agents has clinical potential. Clinical studies of this combination are in progress. We studied the optimal schedule of paclitaxel and methotrexate in combination at various schedules in vitro using human lung cancer A549, breast cancer MCF7, ovarian cancer PA1, and colon cancer WiDr cells. Cells were simultaneously exposed to paclitaxel and methotrexate for 24 h and sequentially exposed to paclitaxel for 24 h followed by methotrexate for 24 h or vice versa. Cell growth inhibition after 5 days was determined by a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The effects of drug combinations at the concentration of drug that produced 80% cell growth inhibition (the IC80 level) were analyzed by the isobologram method. The simultaneous exposure to paclitaxel and methotrexate produced additive to antagonistic effects in the A549 and PA1 cells, and antagonistic effects in the MCF7 and WiDr cells. The sequential exposure to paclitaxel followed by methotrexate produced additive effects in all four cell lines. The reverse sequence produced synergistic effects in the A549, MCF7, and WiDr cells, and additive effects in the PA1 cells. These findings suggest that a sequential administration of methotrexate followed by paclitaxel may be the appropriate schedule for this combination. On the basis of the observed in vitro synergism, further in vivo and clinical studies are necessary to clarify the toxicity and proposed antitumor effects of this schedule.

Antineoplastic Agents, Phytogenic↗
PubMed1998

[Molecular design of polymer-conjugated cytokines and its application for drug delivery systems].

In recent years, clinical application of recombinant cytokines has been expected as a novel drug for various diseases. However, cytokines have generally poor stability in vivo, so they required of very high doses to achieve sufficient clinical effect. In addition, because cytokines have pleiotropic functions, they would cause unfavourable side-effects. Therefore an drug delivery system (DDS) is necessary for clinical use, which stabilizes the cytokines and potentiates only the expected function from other unfavorable ones in vivo. Then we performed the chemical modification of cytokines with water-soluble polymers to overcome such problems as poor stability and pleiotropic activities. This approach includes some advantages that decrease renal excretion rate of proteins and prevent the degradation by proteases. This would result in prolonging the half-lives of bioactive proteins and potentiating their clinical effects. Interestingly, we found that the polymer-conjugated cytokines, that we named hybrid-cytokines, for instance, polyethylene glycol-modified interleukin-6 (PEG-IL-6), were able to increase selectively in their function of promoting platelet production, but not in other unfavourable functions. This effects were suggested for a result of the change in the systemic distribution pattern by pegylation of proteins. In this review, we proposed that the DDS using hybrid-cytokines would be able to increase the stability and regulate the spectrum of the functions of the cytokines by controlling the pharmacokinetics and pharmacodynamics in vivo. This will provide a fundamental information enabling us to design the hybrid-proteins applicable to therapeutic use.

Cytokines↗
PubMed1997

Bioconjugation of tumor necrosis factor-alpha with the copolymer of divinyl ether and maleic anhydride increasing its antitumor potency.

To enhance the therapeutic usefulness of antitumor cytokines in vivo, we synthesized bioconjugated tumor necrosis factor-alpha (TNF-alpha) with divinyl ether and maleic anhydride copolymer (DIVEMA), which has intrinsic antitumor activity as a synthetic biological response modifier. The degree of modification could be controlled by the addition of 2,3-dimethylmaleic anhydride (DMMAn), which binds to amino groups of TNF-alpha by changing the pH. In addition, the specific activity of DIVEMA-TNF-alpha was hardly decreased in vitro. DIVEMA-TNF-alpha showed a marked antitumor effect compared to native TNF-alpha without any side effects such as sudden death, body-weight reduction, and decrease in platelet count on mice bearing solid tumors. These results suggest that DIVEMA is a useful polymeric modifier for-bioconjugation of TNF-alpha in order to increase its antitumor activity, and multifunctionally bioconjugated TNF-alpha may be a potentiated antitumor agent for therapeutic use.

Animals↗
PubMed1997

Antibody-based therapy targeting tumor vascular endothelial cells suppresses solid tumor growth in rats.

We have developed a new approach to antibody-based therapy of solid tumors by targeting tumor vascular endothelial cells (EC) which are essential for the growth of solid tumors. We investigated the effect of an antibody against tumor-derived endothelial cells (TEC) on the growth of solid tumors in rats. Intravenous administration of TES-23, a monoclonal antibody generated by TEC isolated from rat KMT-17 solid tumors, at 1 mg/rat/day for 5 days resulted in significant suppression of KMT-17 tumor growth. Histopathological analysis of tumors administered with TES-23 showed that adhesion of lymphocytes to EC followed by denudation of EC in the viable tumor area. In contrast, little obvious toxicity was observed in most of the rat organs examined. These findings suggest that the concept of an antibody-based therapy with targeting tumor vascular EC would be promising in treatment of solid tumors.

Animals↗
PubMed1997

A multivalent PDZ-domain protein assembles signalling complexes in a G-protein-coupled cascade.

How are signalling molecules organized into different pathways within the same cell? In Drosophila, the inaD gene encodes a protein consisting of five PDZ domains which serves as a scaffold to assemble different components of the phototransduction cascade, including the principal light-activated ion channels, the effector phospholipase C-beta and protein kinase C. Null inaD mutants have a dramatically reorganized subcellular distribution of signalling molecules, and a total loss of transduction complexes. Also, mutants defective in a single PDZ domain produce signalling complexes that lack the target protein and display corresponding defects in their physiology. A picture emerges of a highly organized unit of signalling, a 'transduclisome', with PDZ domains functioning as key elements in the organization of transduction complexes in vivo.

Amino Acid Sequence↗
PubMed1997

Retinoblastoma protein expression and MIB-1 correlate with survival of patients with malignant astrocytoma.

BACKGROUND: Regulatory coupling of cell proliferation and apoptosis is suggested by recent findings with regard to certain tumors, such as the finding of tumor resistance to anticancer therapy caused by inhibition of apoptosis. The processes leading to apoptosis appear to be regulated by a variety of oncogenes and tumor suppressor genes. In the current study, the relation between apoptosis and expression of retinoblastoma protein (pRB) was assessed in 50 primary anaplastic astrocytomas (AAs) and 46 recurrent tumors in the same patients as the primary tumors after macroscopic total surgical resection and chemoradiotherapy. METHODS: Apoptotic cells were identified by the in situ 3'-end labeling technique. Proliferative potential, pRB expression, and p53 expression were evaluated immunohistochemically using anti-Ki-67 (MIB-1), anti-pRB, and anti-p53 antibodies, respectively. The prognostic value of these biologic markers in AA patients undergoing treatment was also evaluated. RESULTS: The mean apoptotic index (AI) was 0.91 +/- 0.70% for specimens obtained at the initial surgery and 2.32 +/- 1.71% for those obtained at recurrence. There was no apparent correlation between the AI and the MIB-1 staining index (MI) in primary AAs, whereas significantly higher AI and MI were observed in recurrent pRB negative cases than in their pRB positive counterparts. The survival of patients with AAs showing a high MI and negative pRB immunostaining was significantly shorter than in the other cases. Neither the size of the apoptotic fraction nor the p53 expression in primary tumor correlated with the overall survival. CONCLUSIONS: The clinical outcome of patients with AA may be associated with aberrant pRB function and increased proliferative activity rather than an inability of tumor cells to undergo apoptosis.

Adult↗
PubMed1997

Clinical and prognostic significance of femoral marrow magnetic resonance imaging in patients with malignant lymphoma.

We evaluated 56 consecutive patients with newly diagnosed lymphoma including 48 with non-Hodgkin's lymphoma (NHL) and 8 with Hodgkin's disease to determine the clinical and prognostic significance of magnetic resonance imaging (MRI) of the femoral marrow. MR images of the femoral marrow were obtained by the T1-weighted spin echo method and the short TI inversion recovery technique. Abnormal "positive" images were seen in 29 of the 56 patients (52%). All 17 patients with positive biopsy results showed abnormal images on their femoral marrow MRI. Three "positive" MRI patterns-scattered (72%), uniform (21%), and nodular (7%)-were observed. The overall survival of the patients with a positive MRI pattern was significantly poorer than that of patients with a normal pattern (P = .0129). Survival did not differ significantly according to MRI pattern. The 3-year survival rate in the patients with a normal MRI pattern was 89.9% and in the patients with a positive MRI pattern, it was 41.0%. This difference was statistically significant (P = .0279) when we evaluated only the patients with NHL. Patients with positive MRI patterns, but a normal bone marrow histology, showed a significantly shorter survival than those with a normal MRI pattern (P = .016). These results indicate that abnormal MR images of the femoral marrow are associated with a significantly poorer survival in patients with malignant lymphoma, regardless of histologic findings in the marrow.

Adolescent↗
PubMed1997

A case of Sjögren's syndrome associated with Sweet's syndrome.

We report a case of Sjögren's syndrome whose clinical course had been indolent until the patient presented with Sweet's syndrome (acute febrile neutrophilic dermatosis). This patient showed renal failure and renal tubular acidosis. Sweet's syndrome resolved within 3 weeks without corticosteroid therapy. Renal biopsy findings were consistent with interstitial nephritis. His renal manifestations responded to corticosteroid therapy and the renal function remained stable during 6 years follow-up without recurrence of Sweet's syndrome. Although close association of both syndromes is already known, in our case Sjögren's syndrome may have been exacerbated by occurrence of Sweet's syndrome.

Acute Kidney Injury↗
PubMed1997

Genomic alterations of human gliomas detected by restriction landmark genomic scanning.

Alterations of genomic DNA in eight primary astrocytic tumors and two glioma cell lines were examined using a recently developed two-dimensional gel electrophoresis method called restriction landmark genomic scanning (RLGS). RLGS allows us to detect amplifications, deletions, and methylation in genomic DNA in one procedure without requiring any polymorphic markers. Approximately 2000 spots (landmark sites) in tumor specimens were compared with those in normal brain tissue. The 10 spots with intensified signal were reproducibly detected in at least 50% of primary tumors, implying amplification of corresponding DNA sequences. Conversely, 12 spots with reduced signal were observed in more than 50% of all tumors, suggesting inactivation by allelic loss, homozygous deletion, or CpG island methylation. These results suggest that common genetic alterations are closely correlated with the genesis or progression of human gliomas.

Brain Neoplasms↗