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Biomedical subjects

S Tsunoda

Publications and source records attributed to S Tsunoda.

At least 55 records · Page 3Linked to original sources
PubMed1999

Inhibition of mutant p53 phosphorylation at serine 15 or serine 315 partially restores the function of wild-type p53.

The tumor suppressor protein p53 is a phosphoprotein and has growth and transformation suppression functions. Phosphorylation of wild-type p53 is known to modulate its function. To investigate the role of phosphorylation in modulating the functions of mutant p53, we constructed a series of phosphorylation site mutants based on mutant p53 Ala143 (p53-143) and p53 His175 (p53-175). When transfected into p53-negative Saos-2 cells, parental mutant p53-143 and p53-175 abolished both growth suppression and induction of apoptosis. However, DNA-activated protein kinase (DNA-PK) or cyclin-dependent kinase (cdks) phosphorylation site double mutants partially restored the growth suppression and induction of apoptosis and recovered the p53-specific DNA binding activity. We also observed a difference in sensitivity to calpain from parental mutants p53-175 and p53-175/15 or p53-175/315. These results suggest that the lack of phosphorylation at either the DNA-PK or cdks site in p53 mutants partially restores the wild-type functions by altering their conformation.

Apoptosis↗
PubMed1999

Tumor vascular targeting using a tumor-tissue endothelium-specific monoclonal antibody as an effective strategy for cancer chemotherapy.

In this study, we attempted to develop tumor vascular targeting with a tumor tissue endothelium-specific monoclonal antibody. TES-23, which strongly and selectively recognizes tumor tissue endothelial cells, was chemically conjugated with Neocarzinostatin (NCS), and the anti-tumor effect was examined. The immunoconjugate, TES-23-NCS, showed, through the use of tumor hemorrhagic necrosis, a marked anti-tumor effect on KMT-17 tumors in rats at a dosage of 17 micrograms/kg (NCS equivalent) without any side effects, probably due to specific tumor vascular injury. By contrast, TES-23 alone (107 micrograms/kg), NCS alone (17 micrograms/kg), and Mopc-NCS (Mopc, 107 micrograms/kg; NCS, 17 micrograms/kg), the immunoconjugate of control antibody, did not have any anti-tumor activities. By tissue distribution analysis, TES-23 and TES-23-NCS showed high accumulation in KMT-17 tumors 1 h after intravenous administration. Moreover TES-23 also accumulated in Sarcoma-180 tumors in mice 1 h after intravenous administration. These results suggest that TES-23 may be a candidate for a potential tumor vascular targeting agent that is applicable to a wide variety of tumor types.

Animals↗
PubMed1999

Molecular design of conjugated tumor necrosis factor-alpha: synthesis and characteristics of polyvinyl pyrrolidone modified tumor necrosis factor-alpha.

We conjugated tumor necrosis factor-alpha (TNF-alpha) with the synthetic polymeric modifier polyvinyl pyrrolidone (PVP) to facilitate its clinical use for anti-tumor therapy. TNF-alpha was chemically conjugated with the terminal carboxyl-bearing PVP at one end of its main chain, which was radically polymerized via the formation of an amide bond between the lysine amino groups of TNF-alpha and carboxyl group of PVP. In vitro specific bioactivity of PVP-conjugated TNF-alpha (PVP-TNF-alpha) relative to that of native TNF-alpha gradually decreased with increases in the degree of PVP attachment. In contrast, PVP-TNF-alpha in which 40% of TNF-alpha lysine residues were coupled with PVP (MPVP-TNF-alpha) exhibited the highest anti-tumor activity among the conjugated derivatives examined. MPVP-TNF-alpha had more than 200-fold higher anti-tumor efficacy than native TNF-alpha, and the anti-tumor activity of MPVP- TNF-alpha was more than 5-fold stronger than that MPEG- TNF-alpha which had the highest anti-tumor activity among PEG-conjugated TNF-alphas examined. Additionally, a high dose of native TNF-alpha induced toxic side-effects such as body weight reduction, piloerection and tissue inflammation, while no side effects were observed following i.v. administration of MPVP-TNF-alpha. The plasma half-life of MPVP-TNF-alpha (360 min) was about 80 and 3-fold longer than those of native TNF-alpha (4.6 min) and MPEG-TNF-alpha (122 min), respectively. These results suggested that PVP is a useful polymeric modifier for increasing the anti-tumor activity of PVP.

Animals↗
PubMed1999

Effect of renal disease and hemodialysis on foscarnet pharmacokinetics and dosing recommendations.

BACKGROUND: Foscarnet is an antiviral agent commonly used for managing patients with cytomegalovirus infection. Despite its clinical usefulness, foscarnet is associated with substantial adverse effects including nephrotoxicity. Moreover, foscarnet is primarily eliminated unchanged through the kidneys, thus requiring aggressive dose adjustment during kidney failure. To develop specific dosage guidelines, information on the disposition of this compound in patients with varying degrees of renal function and those requiring dialysis is essential. DESIGN: Twenty-six subjects were enrolled in this study and divided into five groups depending on their degree of renal dysfunction. Group 1 included subjects with normal renal function; group 5 included subjects requiring maintenance hemodialysis. Nondialysis study subjects received a single 60-mg/kg intravenous dose of foscarnet whereas hemodialysis subjects received two intravenous doses, separated by 1 week, to compare the effects of conventional and high-flux dialysis methods. RESULTS: Mean plasma clearance in control subjects averaged 2.1+/-0.7 ml/minute/kg and declined proportionally with changing renal function as indicated by the regression equation: Clp (ml/minute/kg) = 1.48 [CrCl (ml/minute/kg)]-0.08 (r2 = 0.82). Mean half-life averaged 1.9+/-0.1 hours in normal subjects and increased to a mean of 25+/-19 hours in study subjects with severe impairment not on dialysis. Foscarnet dialysis clearance (based on dialysate recovery) averaged 183 ml/minute with conventional dialysis methods and 253 ml/minute during high-flux procedures, which resulted in removal of 37% and 38% of a dose for the two methods, respectively. CONCLUSIONS: These data indicate that substantial dosage adjustments must be made in renal failure patients. Therefore, a patient-specific dosage nomogram has been developed.

Adult↗
PubMed1999

Bioconjugation of laminin peptide YIGSR with poly(styrene co-maleic acid) increases its antimetastatic effect on lung metastasis of B16-BL6 melanoma cells.

A comb-shaped polymeric modifier, SMA [poly(styrene comaleic anhydride)], which binds to plasma albumin in blood was used to modify the synthetic cell-adhesive laminin peptide YIGSR, and its inhibitory effect on experimental lung metastasis of B16-BL6 melanoma cells was examined. YIGSR was chemically conjugated with SMA via formation of an amide bond between the N-terminal amino group of YIGSR and the carboxyl anhydride of SMA. The antimetastatic effect of SMA-conjugated YIGSR was approximately 50-fold greater than that of native YIGSR. When injected intravenously, SMA-YIGSR showed a 10-fold longer plasma half-life than native YIGSR in vivo. In addition, SMA-YIGSR had the same binding affinity to plasma albumin as SMA, while native YIGSR did not bind to albumin. These findings suggested that the enhanced antimetastatic effect of SMA-YIGSR may be due to its prolonged plasma half-life by binding to plasma albumin, and that bioconjugation of in vivo unstable peptides with SMA may facilitate their therapeutic use.

Animals↗
PubMed1999

Prolonged sympathetic reflex latency on skin nerves in sporadic cerebellar degeneration.

BACKGROUND: Many physiological or pharmacological evaluations of autonomic function have been performed in patients with various types of cerebellar degeneration (CD). Few studies have been done, however, using neurographic recordings in patients with CD, especially of sudomotor or vasoconstrictor nerves. OBJECTIVE: To confirm the clinical importance of sympathetic reflex latencies on the skin nerves of patients with various types of CD. DESIGN AND SETTING: Case-comparison study at an academic center. PARTICIPANTS: We studied 12 patients who had sporadic CD (cerebellar cortical atrophy, olivopontocerebellar atrophy, and Shy-Drager syndrome) and 15 healthy volunteers as controls. METHODS: Skin sympathetic nerve activity (SSNA), sympathetic skin response, and skin vasomotor reflex were simultaneously recorded using randomly administered electrical stimuli. RESULTS: In controls, SSNA reflex latency ranged from 640 to 864 milliseconds. Patients with cerebellar cortical atrophy exhibited slight but significant (P<.01) prolongation of reflex latency to the onset of reflex bursts. In patients with olivopontocerebellar atrophy, latency to the onset and the peak of reflex bursts was significantly prolonged (P<.001). Patients with Shy-Drager syndrome had no SSNA, sympathetic skin response, or skin vasomotor reflex, even with supramaximal electrical stimuli. CONCLUSIONS: Prolonged reflex latency or the absence of reflex bursts on SSNA can be observed in patients with CD with various forms of autonomic dysfunction. The measurement of SSNA reflex latency may be a useful method of evaluating sympathetic function, including the central pathway.

Aged↗
PubMed1999

Schedule-dependent interactions between paclitaxel and etoposide in human carcinoma cell lines in vitro.

Clinical studies of paclitaxel in combination with etoposide against solid tumors have been carried out. The combination schedules used in these studies are different. We studied the cytotoxic effects of paclitaxel with etoposide against four human cancer cell lines in vitro to determine the optimal schedule of this combination at the cellular level. Cells were exposed simultaneously to paclitaxel and to etoposide for 24 h or sequentially to one drug for 24 h followed by the other for 24 h, after which they were incubated in drug-free medium for 4 and 3 days, respectively. Cell growth inhibition was determined by an MTT reduction assay. The effects of drug combinations at concentrations producing 80% inhibition (IC(80)) were analyzed by the isobologram method of Steel and Peckham. The cytotoxic effect of paclitaxel and etoposide was cell line- and schedule-dependent. Simultaneous exposure to paclitaxel and etoposide for 24 h produced additive effects in the lung cancer cell line A549 and ovarian cancer PA1 cells, and antagonistic effects in the breast cancer cell line MCF7 and colon cancer WIDr cells. Sequential exposures to paclitaxel followed by etoposide and vice versa produced additive effects in all four cell lines. These results suggest that maximum cytotoxic effects can be obtained with sequential administration, but not simultaneous administration, of paclitaxel and etoposide. These findings may have important clinical implications for this combination.

Breast Neoplasms↗
PubMed1999

Involvement of prostaglandins in histamine H1 receptor-operated Ca2+ entry in human gingival fibroblasts.

In the absence of external Ca2+, 100 microM histamine evoked a transient increase in intracellular Ca2+ ([Ca2+]i), and subsequent addition of Ca2+ to the medium resulted in a sustained increase in [Ca2+]i in fura-2-loaded human gingival fibroblasts. These Ca2+ mobilizations are attributed to Ca2+ release from intracellular stores and Ca2+ entry, respectively. When the histamine H1 antagonist chlorpheniramine was added after the histamine-induced transient increase in [Ca2+]i, the Ca2+ entry induced by the addition of Ca2+ was inhibited. In the fibroblasts pretreated with cyclooxygenase inhibitors, indomethacin (1 microM) or aspirin (100 microM), histamine-induced Ca2+ entry was significantly inhibited, but not the transient [Ca2+]i increase. These results suggest that the histamine-induced Ca2+ entry requires the continuous binding of histamine to the H1 receptors and is regulated by prostaglandins, which are probably produced due to the H1 receptor activation.

Aspirin↗
PubMed1999

Schedule-dependent interactions between vinorelbine and paclitaxel in human carcinoma cell lines in vitro.

Vinorelbine and paclitaxel are new anticancer agents that bind to distinct sites on tubulin and affect microtubules in opposite ways. Clinical studies of combinations of these agents have been in progress against breast cancer and some solid tumors. To clarify the optimal schedule for this combination, we studied the schedule-dependent cytotoxic effects of vinorelbine and paclitaxel against the human lung carcinoma cell line A549, the breast carcinoma cell line MCF7, the ovarian carcinoma cell line PA1, and the colon carcinoma cell line WiDr in vitro. Tumor cells were incubated with vinorelbine and paclitaxel simultaneously for both 24 h and 5 days. Cells were also incubated with vinorelbine for 24 h, followed by a 24-h exposure to paclitaxel and vice versa. Cell growth inhibition after 5 days was determined by MTT assay. The effects of drug combinations at the concentration producing 80% cell growth inhibition (IC80) were analyzed by the isobologram method (Steel and Peckham). The simultaneous exposures to vinorelbine and paclitaxel for both 24 h and 5 days produced additive effects for all four cell lines. The sequential exposure to vinorelbine followed by paclitaxel produced additive effects for the PA1 and WiDr cells, additive and antagonistic effects for the A549 cells, and antagonistic effects for the MCF7 cells. The sequential exposure to paclitaxel followed by vinorelbine produced additive effects for the A549, and PA1 cells, additive and antagonistic effects for the MCF7 cells, and antagonistic effects for the WiDr cells. Our findings suggest that the simultaneous rather than the sequential administration of vinorelbine and paclitaxel may be the optimal schedule for this combination of these two agents. Applications of this schedule dependency may be beneficial for the treatment of breast cancer and other solid tumors.

Antineoplastic Agents, Phytogenic↗
PubMed1999

Specific binding of TES-23 antibody to tumour vascular endothelium in mice, rats and human cancer tissue: a novel drug carrier for cancer targeting therapy.

The tissue distribution of anti-tumour vascular endothelium monoclonal antibody (TES-23) produced by immunizing with plasma membrane vesicles from isolated rat tumour-derived endothelial cells (TECs) was assessed in various tumour-bearing animals. Radiolabelled TES-23 dramatically accumulated in KMT-17 fibrosarcoma, the source of isolated TECs after intravenous injection. In Meth-A fibrosarcoma, Colon-26 adenocarcinoma in BALB/c mice and HT-1080 human tumour tissue in nude mice, radioactivities of 125I-labelled TES-23 were also up to 50 times higher than those of control antibody with little distribution to normal tissues. The selective recognition of TES-23 to TECs was competitively blocked by preadministration of unlabelled TES-23 in vivo. Furthermore, immunostaining of human tissue sections showed specific binding of TES-23 on endothelium in oesophagus cancers. These results indicate that tumour vascular endothelial cells express common antigen in different tumour types of various animal species. In order to clarify the efficacy of TES-23 as a drug carrier, an immunoconjugate, composed of TES-23 and neocarzinostatin, was tested for its anti-tumour effect in rats bearing KMT-17 fibrosarcomas. The immunoconjugate (TES-23-NCS) caused marked regression of the tumour, accompanied by haemorrhagic necrosis. Thus, from a clinical view, TES-23 would be a novel drug carrier because of its high specificity to tumour vascular endothelium and its application to many types of cancer.

Adenocarcinoma↗
PubMed1999

The organization of INAD-signaling complexes by a multivalent PDZ domain protein in Drosophila photoreceptor cells ensures sensitivity and speed of signaling.

Phototransduction in Drosophila has emerged as an attractive model system for studying the organization of signaling cascades in vivo. In photoreceptor neurons, the multivalent PDZ protein INAD serves as a scaffold to assemble different components of the phototransduction pathway, including the effector PLC, the light-activated ion channel TRP, and a protein kinase C involved in deactivation of the light response. INAD is required for organizing and maintaining signaling complexes in the rhabdomeres of photoreceptors. This macromolecular organization endows photoreceptors with many of their signaling properties, including high sensitivity, fast activation and deactivation kinetics, and exquisite feedback regulation by small localized changes in [Ca2+]i. Assembly of transduction components into signaling complexes is also an important cellular strategy for ensuring specificity of signaling while minimizing unwanted cross-talk. In this report, we review INAD's role as a signal transduction scaffold and its role in the assembly and localization of photoreceptor complexes.

Animals↗
PubMed1999

Muscle sympathetic activity in cerebellar degeneration with or without mild autonomic dysfunction.

To evaluate autonomic function in sporadic cases of cerebellar degeneration (CD) with or without mild autonomic dysfunction, we measured muscle sympathetic nerve activity (MSNA) by microneurography in 12 CD patients and 18 healthy subjects. The burst incidence and mean amplitude of MSNA at rest was significantly decreased in CD patients (P < 0.01). There were no significant differences between patients with CD and controls in heart rate or blood pressure at rest. During head-up tilting, increases in blood pressure and mean amplitude of MSNA were significantly lower in CD patients. In conclusion, a decrease in muscle sympathetic outflow can be observed even in CD patients who are clinically excluded from multiple system atrophy (MSA). It might be difficult to distinguish other CD syndromes from MSA in recordings of muscle sympathetic activity.

Adult↗
PubMed1999

Genomic alterations in human meningiomas detected by restriction landmark genomic scanning and immunohistochemical studies.

Using restriction landmark genomic scanning (RLGS) methods, 21 samples of human meningioma were analyzed. We found 3 alterations in the genomic DNAs of tumor samples located on chromosomes 5, 14 and 17 which appear to be common to the meningothelial subtype. Two other separate genetic abnormalities located on chromosomes 9-12 and 20 are apparently associated with atypical meningiomas. In addition, the neurofibromatosis type 2 gene is apparently involved in more than half of the tumor samples. There appear to be both common and type-specific genetic mutations associated with the formation and progression of human meningiomas.

Adult↗
PubMed1999

Enhanced antitumor potency of polyethylene glycolylated tumor necrosis factor-alpha: a novel polymer-conjugation technique with a reversible amino-protective reagent.

We attempted to develop a novel method for the chemical modification of cytokines with synthetic polymers to increase in vivo therapeutic efficacy. A pH-reversible amino-protective reagent, dimethylmaleic anhydride (DMMAn), was used for polymer conjugation of tumor necrosis factor-alpha (TNF-alpha) with polyethylene glycol (PEG). The novel PEGylated TNF-alpha, PEG-TNF-alpha(+), which was pretreated with DMMAn before PEGylation, had 20% to 40% higher specific activity than PEG-TNF-alpha(-) (not treated with DMMAn) in vitro. Moreover, PEG-TNF-alpha(+) more potently caused tumor necrosis in Meth-A solid tumors in mice than did PEG-TNF-alpha(-). The middle fraction (M) of PEG-TNF-alpha(+), which was of the optimal degree of modification among PEG-TNF-alpha(+)s with different molecular weights, caused the highest degree of tumor hemorrhagic necrosis: 30-fold higher than native TNF-alpha and 2-fold higher than the most potent MPEG-TNF-alpha(-) that also had nearly the same molecular weight. Significantly, improvements in antitumor activity in vivo were more marked than were changes in specific activity. Furthermore, native TNF-alpha caused a dose-dependent body weight loss in mice, whereas no obvious side effects were observed in any PEG-TNF-alpha-treated mice. These results suggest that PEGylation using DMMAn is a useful for clinical cytokine delivery.

Animals↗
PubMed1999

Decreased host-cell reactivation of UV-irradiated adenovirus in human colon tumor cell lines that have normal post-UV survival.

An ongoing study in our laboratories is to examine the relationship of DNA repair defects to human cancer. Our underlying hypothesis has been that human tumors may arise that lack interesting DNA repair pathways if these pathways are important in preventing cancer. In this study, we found that the UV-irradiated adenoviruses showed hypersensitivity when assayed on monolayers of certain human colon tumor cell lines, including three that are reported to have defects in long patch DNA mismatch repair genes and one with no reported defect in mismatch repair. The survival curves showed two components. The first sensitive component was characteristic of 77-95% of the infections depending upon the cell line and the experiment and had an average slope indicating 4.8-fold hypersensitivity to UV. The average of the second-component slopes indicated that the remainder of the infections was accompanied by near-normal repair. Although the value of the first component indicated that the colon tumor lines supported the growth of UV-damaged adenoviruses poorly, the cell lines themselves showed the same post-UV colony-forming ability as did normal human fibroblasts, and their ability to support the growth of N-methyl-N'-nitro-N-nitrosoguanidine-damaged adenoviruses was normal, i.e. it parallelled their ability to repair O6-methylguanine in vitro. We previously observed two-component survival curves when assaying UV-irradiated adenovirus on monolayers of all of seven strains of fibroblasts from Cockayne's syndrome patients. By contrast, single-component curves have been obtained using 21 strains of normal human fibroblasts and seven other tumor lines. We interpret the two-component survival curves in terms of the defective transcription-coupled repair of UV-induced DNA damage that is characteristic both of Cockayne's and certain colon tumor cell lines. In addition, four mismatch repair-deficient colon tumor lines were resistant to killing by elevated levels of dG.

Adenoviruses, Human↗
PubMed1999

[A case of neuroleptic malignant syndrome associated with reversible leukoencephalopathy].

We report a case of neuroleptic malignant syndrome associated with reversible leukoencephalopathy. The patient was a 60-year-old woman. Soon after ingesting an antipsychotic drug, the patient developed neuroleptic symptoms. After hydration and dantrolene sodium were administered, muscular rigidity gradually improved and serum levels of CK became normal. On the 7th hospital day, however, she fell into coma and showed tetraplegia. Although brain CT was normal on admission, diffuse low density areas were observed on the parieto-occipital cerebral white matter. The same lesions were observed on T2-weighted MRI. On the 20th hospital day, after giving her glycerol and adrenocorticosteroid, not only abnormal neurological findings but also abnormal CT and MRI findings disappeared. There were only two case reports of leukoencephalopathy with malignant syndrome in the literature. This is a rare case of reversible leukoencephalopathy with neuroleptic malignant syndrome due to the antipsychotic drug.

Adrenal Cortex Hormones↗
PubMed1998

Identification of tumor vascular antigens by monoclonal antibodies prepared from rat-tumor-derived endothelial cells.

We have reported the isolation and specific in vitro properties of tumor-derived endothelial cells (TEC) from rat KMT-17 fibrosarcomas transplanted into rats. To develop antibody-based tumor vascular targeting therapy for solid tumors, we have generated monoclonal antibodies (MAbs) using passive immunization of outside-out membrane vesicles of rat epididymal-fat-pad-derived capillary endothelial cells (FCEC) followed by active immunization of those of rat TEC. The MAbs produced were screened against TEC and FCEC. Of all cultured hybridomas, 75 (3.3%) of the secreted MAbs preferentially recognized TEC. We selected a total of 7 MAbs which detected antigens highly abundant in TEC, although 5 of the 7 MAbs were weakly positive for FCEC in cell-ELISA and FACS analyses. The antigens recognized by these MAbs, with the exception of MAb TES-7, were present on endothelial cells of tumor blood vessels in KMT-17 fibrosarcoma tissues, as shown by immunohistochemical analysis. Antigens of 40- and 80-kDa were recognized by MAbs TES-1, 7, 17, 21 and 26 and by MAbs TES-23 and 27 respectively. Although the function of these antigens, which are preferentially expressed on rat tumor-derived endothelial cells, is still unknown, we believe that future studies of such antigens will help elucidate the role of endothelial cells in tumor vasculature. Our results indicate that MAbs may provide a novel tool for the development of antibody-based therapy targeting tumor vasculature.

Animals↗