Biomedical subjects

T Yoshioka

Publications and source records attributed to T Yoshioka.

At least 217 records · Page 12Linked to original sources

PubMed1998

Evidence for the involvement of inositol trisphosphate but not cyclic nucleotides in visual transduction in Hermissenda eye.

Although several second messengers are known to be involved in invertebrate photoresponses, the mechanism underlying invertebrate phototransduction remains unclear. In the present study, brief injection of inositol trisphosphate into Hermissenda photoreceptors induced a transient Na+ current followed by burst activity, which accurately reproduced the native photoresponse. Injection of Ca2+ did not induce a significant change in the membrane potential but potentiated the native photoresponse. Injection of a Ca2+ chelator decreased the response amplitude and increased the response latency. Injection of cGMP induced a Ca2+-dependent, transient depolarization with a short latency. cAMP injection evoked Na+-dependent action potentials without a rise in membrane potential. Taken together, these results suggest that phototransduction in Hermissenda is mediated by Na+ channels that are directly activated by inositol trisphosphate without mobilization of cytosolic Ca2+.

Animals↗

PubMed1998

Anticancer efficacy in vivo and in vitro, synergy with 5-fluorouracil, and safety of recombinant methioninase.

The elevated exogenous-methionine dependency of tumors for growth has been observed in all major cancer cell types. We have previously cloned a methioninase (rMETase) from Pseudomonas putida to deplete methionine. Growth inhibition followed by apoptotic cell death was induced by treatment of tumor cells with rMETase in vitro. A single i.p. injection of 300 units of rMETase can lower the serum methionine level in the mice from 70 microM to less than 1 microM within 2 h and maintain this depleted level for 8 h. Repeated dosing of rMETase of tumor-bearing mice could be administered without acute immune-hypersensitivity. rMETase treatment demonstrated growth inhibitory activity against human tumors in nude mice, including those which were multiple drug-resistant. No body weight loss or hematotoxicity, except a slight anemia, was found throughout the therapy. The combined treatment of the Lewis lung carcinoma with a fixed rMETase dose and increasing doses of 5-fluorouracil (5-FU) resulted in a dose-dependent enhanced antitumor efficacy for survival as well as tumor growth inhibition. Thus, methionine depletion by rMETase potentiates the antitumor efficacy of 5-FU. The data presented in this report thus indicate that rMETase is active alone, is synergistic in combination with 5-FU, and has negligible toxicity suggesting a novel clinical approach for effective cancer therapy.

Animals↗

PubMed1998

Reduced angiogenesis and tumor progression in gelatinase A-deficient mice.

Matrix proteolysis is thought to play a crucial role in several stages of tumor progression, including angiogenesis, and the invasion and metastasis of tumor cells. We investigated the specific role of gelatinase A (matrix metalloproteinase 2) on these events using gelatinase A-deficient mice. In these mice, tumor-induced angiogenesis was suppressed according to dorsal air sac assay. When B16-BL6 melanoma cells or Lewis lung carcinoma cells were implanted intradermally, the tumor volumes at 3 weeks after implantation in the gelatinase A-deficient mice decreased by 39% for B16-BL6 melanoma and by 24% for Lewis lung carcinoma (P < 0.03 for each tumor). The number of lung colonies of i.v. injections fell by 54% for B16-BL6 melanoma and 77% for Lewis lung carcinoma (P < 0.014 and P < 0.0015, respectively). These results indicated that host-derived gelatinase A plays an important role in angiogenesis and tumor progression, suggesting the usefulness of gelatinase A inhibitors for anticancer chemotherapy.

Animals↗

PubMed1998

Formation of N-Arylacylhydroxamic Acids from Nitroso Aromatic Compounds in Isolated Spinach Leaf Cells.

The formation of N-arylacetohydroxamic acids from nitroso aromatic compounds in the presence of pyruvate was investigated using isolated spinach leaf cells. The activity was enhanced by the addition of TPP, MgSO(4), and pyruvate, requirements for pyruvate dehydrogenase complex (PDHC). Measurement of the kinetic parameters revealed that the K(m) values of nitroso aromatic compounds tested were identical and that electron-donating ring substituents decreased the catalytic efficiency. The activation energy of the formation of N-phenylacetohydroxamic acid was lower than that reported for porcine heart PDHC. With alpha-oxo acids tested, alpha-oxobutyrate served as a substrate to give the corresponding N-phenylpropionylhydroxamic acid. The activity of spinach leaf cells in N-phenylacetohydroxamic acid formation was found in both mitochondria and chloroplasts. The contribution of chloroplast PDHC to total activity in the formation of N-phenylacetohydroxamic acid was estimated to be 50% under the conditions used.

Journal Article↗

PubMed1998

Highly selective and orally active inhibitors of type IV collagenase (MMP-9 and MMP-2): N-sulfonylamino acid derivatives.

Various N-sulfonylamino acid derivatives were synthesized and evaluated for their in vitro and in vivo activities to inhibit type IV collagenase (MMP-9 and MMP-2). When the amino acid residue and the sulfonamide moiety were modified, their inhibitory activities were greatly affected by the structure of the sulfonamide moiety. A series of aryl sulfonamide derivatives containing biaryl, tetrazole, amide, and triple bond were found to be potent and highly selective inhibitors of MMP-9 and MMP-2. In addition, these compounds were orally active in animal models of tumor growth and metastasis. These results revealed the potential of the N-sulfonylamino acid derivatives as a new type of candidate drug for the treatment of cancer.

Administration, Oral↗

PubMed1998

Recognition of rheumatoid arthritis synovial antigen by CD4+,CD8- T cell clones established from rheumatoid arthritis joints.

OBJECTIVE: To investigate the rheumatoid arthritis (RA)-specific autoantigen(s) recognized by CD4+ T cells in patients with RA. METHODS: CD4+,CD45RO+ T cell clones were established from the joints of RA patients, and were examined for their proliferative response to synovial cells. RESULTS: Eight of 146 T cell clones responded to RA synovial cells in a DR-restricted manner. These T cell clones recognized solubilized antigens extracted from RA synovial cells in the presence of DR-matched antigen-presenting cells, but did not respond to those extracted from non-RA synovial cells. The antigens had a molecular weight of 50/25 kd. Five of the 8 T cell clones used T cell receptor BV6, and the remaining clones used BV12.2. CONCLUSION: The antigens recognized by joint-infiltrating CD4+ T cells are present exclusively in RA synovial cells. The expression of these antigens by synovial cells may trigger the autoreactivity of T cells in RA joints.

Amino Acid Sequence↗

PubMed1998

Antiinflammatory potency of dehydrocurdione, a zedoary-derived sesquiterpene.

OBJECTIVE AND DESIGN: Dehydrocurdione, a sesquiterpene isolated from zedoary, was tested for in vivo and in vitro antiinflammatory actions. MATERIALS: Analgesic effect was tested in ICR mice by the acetic acid-induced writhing method. Antipyretic effect was studied in Sprague-Dawley rats treated with baker's yeast. Antiinflammatory activities were tested in Wistar rats with carrageenan-induced paw edema and adjuvant-induced chronic arthritis. In vitro analyses included the capabilities to inhibit cyclooxygenase activity, and to scavenge free radicals as determined by electron paramagnetic resonance (EPR). RESULTS: Oral administration of dehydrocurdione (40 to 200 mg/kg) mitigated the writhing reflex. induced by acetic acid and the fever elicited by baker's yeast. A higher dose (200 mg/kg) of dehydrocurdione was required to inhibit the carrageenan-induced paw edema. Oral administration of dehydrocurdione at 120 mg/kg/day for 12 days significantly reduced chronic adjuvant arthritis. Unlike indomethacin (IC50: 0.1 microM), dehydrocurdione showed minimal cyclooxygenase inhibition. However, dehydrocurdione (100 microM to 5 mM) significantly reduced free radical formation from hydrogen peroxide and ferrous iron determined by EPR spectrometry using 5,5'-dimethyl-1-pyrroline-N-oxide as a spin trap agent. CONCLUSION: In addition to the well-known effect of zedoary as a stomachic, dehydrocurdione, the major component of Curcuma zedoaria Roscoe has antiinflammatory potency related to its antioxidant effect.

Acetic Acid↗

PubMed1998

High urinary excretion level of citrate and magnesium in children: potential etiology for the reduced incidence of pediatric urolithiasis.

It is well known that the incidence of calcium oxalate (CaOX) urolithiasis is much lower in children than in adults [2, 21]. One purpose of this study was to compare the inhibitory activity on CaOX crystal growth and nucleation of urine from children (ufC) with that of urine from adults (ufA). Another was to measure low molecular weight urinary substances related to CaOX lithiasis, including citrate and magnesium, which have been identified as stone inhibitors. The excretion volume per body weight of uric acid, phosphorus, magnesium and citrate was all significantly higher in 24-h ufC than in 24-h ufA, but that of calcium and oxalate was not. The growth inhibitory activities against CaOX crystals of ufC and ufA were measured in a whole urine system. The diameter of the crystals produced in this system was smaller for ufC (3.68 microm) than for ufA (4.66 microm). We also examined the metastable limit for CaOX with fresh spot urine, which was 3.15 mmol/l in ufC and 0.41 mmol/l in ufA. These results indicate that ufC has a more powerful inhibitory effect on CaOX crystal growth and nucleation than ufA. We also found that the excretion rate of citrate and magnesium in ufC was much higher than in ufA. We suggest that these two stone inhibitors are very likely to elevate the inhibitory activity of ufC against CaOX crystal growth and nucleation. The lower incidence of CaOX lithiasis in children might thus be partly attributed to citrate and magnesium.

Adult↗

PubMed1998

Characteristics of two cancer cell lines derived from metastatic foci in liver and peritoneum of a patient with colon cancer.

Two cancer cell lines were established in vitro from a single patient with colon cancer; AKT-CC-K-LM cells from liver metastatic nodules and AKT-CC-K-PC cells from peritoneal dissemination nodules. The two cell lines were similar in doubling time, number of chromosomes, and chromosomal abnormalities. However, they differed in morphology in vitro, in the expression level of cell surface adhesion molecules (carcinoembryonic antigen; CEA, E-cadherin, sialyl Le(a), sialyl Le(x), and CD44v6), and in their metastatic properties. AKT-CC-K-LM cells grew in vitro as adherent clusters and AKT-CC-K-PC cells as adherent single cells. The expression levels of CEA, E-cadherin, sialyl Le(a), and sialyl Le(x) was significantly higher in AKT-CC-K-LM cells. The expression of CD44v6 was significantly higher in AKT-CC-K-PC cells. After the injection of AKT-CC-K-LM cells to the spleen or peritoneal cavity of severe combined immune deficiency mice, metastatic nodules were observed only in the liver. In contrast, the injection of AKT-CC-K-PC cells to the spleen or peritoneal cavity yielded metastatic nodules only in the peritoneal cavity. These cell lines may contribute to elucidating the relationship between cell surface adhesion molecules and the metastatic properties of cancer cells.

Adenocarcinoma↗

PubMed1998

Thermal imaging of receptor-activated heat production in single cells.

Changes in enthalpy (i.e., heat content) occur during the diverse intracellular chemical and biophysical interactions that take place in the life cycle of biological cells. Such changes have previously been measured for cell suspensions or cell-free biochemical extracts by using microcalorimetry, thermocouples, or pyroelectric films, all of which afford minimal spatial or temporal resolution. Here we present a novel thermal imaging method that combines both diffraction-limited spatial (approximately 300 nm) and sampling-rate-limited time resolution, using the temperature-dependent phosphorescence intensity of the rare earth chelate Eu-TTA (europium (III) thenoyltrifluoro-acetonate). With this thermosensitive dye, we imaged intracellular heat waves evoked in Chinese hamster ovary cells after activation of the metabotropic m1-muscarinic receptor. Fast application of acetylcholine onto the cells evoked a biphasic heat wave that was blocked by atropine, and after a brief delay was followed by a calcium wave. Atropine applied by itself produced a monophasic heat wave in the cells, suggesting that its interactions with the receptor activate some intracellular metabolic pathways. The thermal imaging technique introduced here should provide new insights into cellular functions by resolving the location, kinetics, and quantity of intracellular heat production.

Animals↗

PubMed1998

Glomerular endothelial injury associated with free radical production induced by a fungal cell wall component, (1-->3) beta-D glucan.

Clinical evidence suggests that microangiopathy may be induced by fungal infection. The present study evaluated the toxic effect of (1-->3) beta-D glucan, a major component of fungal cell wall, on cultured transformed glomerular endothelial cells (TF-GEN). When TF-GEN were exposed to increasing concentrations of (1-->3) beta-D glucan (beta-DG; 115 to 430 pg/ml) for 1 to 3 hours, concentration- and time-dependent increases in hydroxyl radical production were demonstrated by electron paramagnetic resonance spectrometry using 5, 5-dimethyl-1-pyrrolyne-N-oxide as a spin trap agent. The amount of radicals induced by 230 or 430 pg/ml beta-DG was comparable to that induced by E. coli LPS (1 or 10 microg/ml). The beta-DG-induced free radical production was associated with a subsequent increase in LDH release from TF-GEN. When TF-GEN pretreated with U78517F (0.1 or 1.0 microM), a lipophilic antioxidant, were stimulated with LPS (1 or 10 microg/ml) or beta-DG (230 pg/ml) for 3 hours, free radical production by TF-GEN was significantly reduced in cells pretreated with the higher concentration of U78517F. Thus, fungal (1-->3) beta-D glucan induces glomerular endothelial injury by stimulating cellular free radical production. Such a mechanism may underlie microangiopathy in systemic fungal infections.

Animals↗

PubMed1998

Sequence-dependent antitumour efficacy of combination chemotherapy of nedaplatin, a novel platinum complex, with 5-fluorouracil in an in vivo murine tumour model.

The antitumour efficacy of a sequential combination of nedaplatin (NDP) and 5-fluorouracil (5-FU) was evaluated using Lewis lung carcinoma in vivo. NDP was developed as a second generation platinum complex. Because it has greater antitumour activity and lower nephrotoxicity than cisplatin (CDDP), we also compared the antitumour activity of NDP plus 5-FU with that of CDDP plus 5-FU. A fixed 5-FU dose was injected daily for 5 days and increasing doses of either NDP or CDDP were injected once via the tail vein into the Lewis lung carcinoma-implanted mice. The sequential administration of either NDP or CDDP prior to 5-FU (NF or CF therapy) resulted in severe body weight loss followed by the death of the tumour-bearing mice when the high-dose of NDP or CDDP was administered. In contrast, the sequential administration of 5-FU prior to NDP or CDDP (FN or FC therapy) resulted in synergistically enhanced inhibition of tumour growth and prolonged survival in comparison with NDP, CDDP or 5-FU monotherapy. At the high-dose of NDP in FN therapy, a reduction of tumour size and long-term tumour-free survival were frequently observed. The survival effect of the combinations of NDP with 5-FU was superior to those of the combination of CDDP with 5-FU. In conclusion, the sequence-dependent antitumour efficacy and toxicity of the combination of NDP or CDDP with 5-FU was demonstrated in this study, and FN therapy appeared to be the most efficient regimen as a clinical therapy.

Animals↗

PubMed1998

Inhibition of ischaemic hippocampal neuronal death in primates with cathepsin B inhibitor CA-074: a novel strategy for neuroprotection based on 'calpain-cathepsin hypothesis'.

Although Cornu Ammonis (CA) 1 neurons of the hippocampus are known to be vulnerable to transient ischaemia, the mechanism of ischaemic neuronal death is still unknown, and there are very few strategies to prevent neuronal death at present. In a previous report we demonstrated micro-calpain activation at the disrupted lysosomal membrane of postischaemic CA1 neurons in the monkey undergoing a complete 20 min whole brain ischaemia. Using the same experimental paradigm, we observed that the enzyme activity of the lysosomal protease cathepsin B increased throughout the hippocampus on days 3-5 after the transient ischaemia. Furthermore, by immunocytochemistry cathepsin B showed presence of extralysosomal immunoreactivity with specific localization to the cytoplasm of CA1 neurons and the neuropil of the vulnerable CA1 sector. When a specific inhibitor of cathepsin B, the epoxysuccinyl peptide CA-074 (C18H29N3O6) was intravenously administered immediately after the ischaemic insult, approximately 67% of CA1 neurons were saved from delayed neuronal death on day 5 in eight monkeys undergoing 20 min brain ischaemia: the extent of inhibition was excellent in three of eight and good in five of eight monkeys. The surviving neurons rescued by blockade of lysosomal activity, showed mild central chromatolysis and were associated with the decreased immunoreactivity for cathepsin B. These observations indicate that calpain-induced cathepsin B release is crucial for the development of the ischaemic neuronal death, and that a specific inhibitor of cathepsin B is of potential therapeutic utility in ischaemic injuries to the human CNS.

Animals↗

PubMed1998

Expression of Tamm-Horsfall protein in stone-forming rat models.

OBJECTIVES: To examine the expression of Tamm-Horsfall protein (THP) and calcium oxalate deposition in three rat models to clarify whether THP plays an active role in crystal formation or whether crystals induce the secretion of this protein. MATERIALS AND METHODS: A stone-forming rat model (model 1) with marked tubular dilatation in an entire kidney was produced by rendering Wistar rats (aged 8 weeks) hyperoxaluric and hypercalciuric, through compulsorily feeding with 0.12 mL of 5% ethylene glycol (in two doses daily) and 0.5 microgram of vitamin D3 every other day. Two other rat models were also produced. Model 2 comprised stone-forming rats with minimal tubular dilatation, achieved by giving rats the same dose of ethylene glycol once daily, and model 3 comprised stone-free rats with marked tubular dilatation achieved by unilateral ureteric ligation. The rats' kidneys were resected after 4 weeks and all resected kidneys immunohistochemically stained with an antibody to THP. Simultaneously, the location of calcium oxalate (CaOx) crystals was established with von Kossa staining. The relation between crystals and the secretion of THP was also assessed in vitro. Cultured renal epithelial cells (NRK-52E) were stained with an antibody to THP after they had been cultured for 72 h in a medium containing CaOx crystals. RESULTS: In model-1 kidneys with both tubular dilatation and many crystals, there was local and intense expression of THP in many renal tubules. CaOx crystals and the intense expression of THP tended to occur in the same renal tubules. In model 2 kidneys with little tubular dilatation, only a few renal tubules expressed THP strongly and the location of the crystals rarely coincided with that of THP expression. In model 3 kidneys with marked tubular dilatation but no crystals, THP was expressed strongly in many renal tubules. The expression of THP in cultured NRK-52E cells was not stimulated by CaOx crystals. CONCLUSIONS: The results from the in vivo models suggest that THP did not initiate crystal formation and the strong expression of THP was induced not by crystals but by renal tubular damage caused by tubular dilatation. From the close association of THP and crystals in model 1 kidneys, this protein might play a secondary role as an adhesive, promoting stone formation.

Adjuvants, Immunologic↗

PubMed1998

Therapeutic apheresis for septic patients with organ dysfunction: hemoperfusion using a polymyxin B immobilized column.

A prospective clinical study was performed to evaluate a new method of treatment of endotoxin shock, a column containing polystyrene fibers with covalently bound immobile polymyxin B. Direct hemoperfusion using the column removes circulating endotoxin by adsorption. All of the patients studied, 37 in the treatment group and 33 in the control group, had endotoxemia and failure of 1 or more organs. The perfusion was performed 1-7 times per patient, 2 h/session. The survival rate was significantly higher in the treatment group (54%) than in the controls (36.4%). The mean plasma endotoxin concentration was significantly lowered by the treatment from 83.7 pg/ml before perfusion to 56.4 pg/ml immediately after and 28.5 pg/ml the day after the treatment, and the posttreatment level was much lower in those who survived (mean, 18.8 pg/ml) compared to those who died (mean, 88 pg/ml). Various parameters of cardiac function also improved after the treatment.

Adolescent↗

PubMed1998

Comparison of clinical outcomes of laparoscopic and conventional open adrenalectomy.

From September 1992 to November 1996, 28 patients underwent laparoscopic adrenalectomy at Osaka University Medical Hospital. They were compared with 25 instances of conventional open surgery performed between May 1990 and April 1996 at the same institution. Laparoscopic adrenalectomy was performed via either a transperitoneal or a retroperitoneal approach. The mean operative time of 375 minutes for laparoscopic adrenalectomy was significantly longer than that of 133 minutes for open surgery. The average hospital stay for laparoscopic surgery was significantly shorter than that of conventional open adrenalectomy. The convalescent period was also significantly shorter in the patients who had laparoscopic adrenalectomy. There was no statistical difference in blood loss during the operation or the number of doses of analgesics administered after operation in the two groups. We conclude that laparoscopic adrenalectomy is one of the options to be selected in surgically managing adrenal tumors. Laparoscopic adrenalectomy could become a standard operative procedure as instruments and techniques of laparoscopy improve significantly.

Adolescent↗

PubMed1998

Astrocytoma and B-cell lymphoma development in a man with a p53 germline mutation.

We report a case with a germline mutation of the p53 gene develpoing both a non-Hodgkin's lymphoma and an astrocytoma. The astrocytoma could be cured by two operations and combined chemotherapy but 33 months after the onset of the disease, he suffered from a diffuse, large cell centroblastic malignant lymphoma of B-cell lineage. In spite of clear rearranged fragments observed with IgH and c-MYC gene probes, we could not diagnose a Burkitt's lymphoma morphologically. The malignant lymphoma was chemoresistant and the patient died of multi-organ failure. He was confirmed to have a germline mutation of the p53 gene by analysis of c-DNA from peripheral lymphocytes and loss of heterozygosity (LOH) of p53 was evident in the lymphoma. The results were suggestive of the Li-Fraumeni syndrome (LFS), a rare autosomal dominantly inherited syndrome with a germline mutation of p53 gene and diverse malignancies, but this could not be confirmed in the present case. Alternatively, a de novo mutation could have been involved.

Abdominal Neoplasms↗

PubMed1998

Molecular characterization of the mouse mtprd gene, a homologue of human TPRD: unique gene expression suggesting its critical role in the pathophysiology of Down syndrome.

We and others recently isolated a human TPRD gene, possessing a motif of the tetratricopeptide repeat (TPR), from the Down syndrome-critical region (DCR) of chromosome 21q22.2. In this study, we isolated a mouse homologue of TPRD cDNA, mtprd, and examined its expression profile in mouse embryos. The gene was mapped to mouse chromosome 16C3.3-4, consistent with the location of DCR, and encodes 1,979 amino acid residues with 76% identity to TPRD. The mtprd protein has three units of the TPR motif with 91% homology to TPRD. The protein also has two regions homologous to several matrix proteins with 86 and 70% identities to those of TPRD. Several splicing variants of the 5' portion of the open reading frame of mtprd were identified by RT-PCR and sequencing of mRNAs. In situ hybridization showed that mtprd is ubiquitously expressed in mouse embryos but predominantly in the central nervous system, including the telencephalon, mesencephalon, and metencephalon. These results suggest that the TPRD gene is one of the genes responsible for not only the morphological anomalies but also the neurological abnormalities observed in Down syndrome. The presence of splicing variants indicates that the protein may also have several isoforms in mice.

Amino Acid Sequence↗