Biomedical subjects

S Soeda

Publications and source records attributed to S Soeda.

At least 37 records · Page 2Linked to original sources

PubMed1999

Synthesis and biological evaluation of 1,1-difluoro-2-(tetrahydro-3-furanyl)ethylphosphonic acids possessing a N9-purinylmethyl functional group at the ring. a new class of inhibitors for purine nucleoside phosphorylases.

1,1-Difluoro-2-(tetrahydro-3-furanyl)ethylphosphonic acids cis-3 and trans-3 possessing a N9-purinylmethyl functionality at the ring were synthesized and tested as "multi-substrate analogue" inhibitors for purine nucleoside phosphorylases. Radical cyclization of allyic alpha,alpha-difluorophosphonate (E)-7 was applied to construct the alpha,alpha-difluorophosphonate-functionalized tetrahydrofuranyl moiety. The IC50 values of cis-3 and trans-3 for human erythrocyte PNP-catalyzed phosphorylation of inosine were determined to be 88 and 320 nM, respectively. The stereochemistry of the inhibitors was found to affect significantly the inhibitory potency.

Antineoplastic Agents↗

PubMed1999

Synthesis and biological evaluation of alpha,alpha-difluorobenzylphosphonic acid derivatives as small molecular inhibitors of protein-tyrosine phosphatase 1B.

A series of alpha,alpha-difluorobenzylphosphonic acids having a hydrophobic functional group were prepared via the Stille coupling reaction from halogenated alpha,alpha-difluorobenzylphosphonates. Evaluation of inhibitory activity toward protein tyrosine phosphatase (PTP 1B) revealed that the ethynyl, phenylethynyl and (E)-styryl groups on the benzene nuclei increased the inhibitory activity of alpha,alpha-difluorobenzylphosphonic acid. Inhibitory activities significantly increased upon introducing both (E)-styryl and bis-methylsulfonamide functional groups onto the benzene nuclei of alpha,alpha-difluorobenzylphosphonic acid.

Enzyme Inhibitors↗

PubMed1999

MR findings in primary retroperitoneal schwannoma.

OBJECTIVE: To evaluate the MR findings in primary retroperitoneal schwannoma. MATERIAL AND METHODS: Seven cases of primary retroperitoneal schwannoma, in whom the diagnosis was confirmed histopathologically, were analyzed retrospectively. The following items were reviewed at MR imaging: tumor diameter, margin, homogeneity, signal intensity as compared to normal renal parenchyma, presence/absence of infiltration into adjacent organs, and, in 1 and 4 cases, the enhancement on Gd-dynamic images and post-contrast T1-weighted images, respectively. RESULTS: Tumor diameter was 5.5 +/- 3.1 cm, ranging from 2.5 to 10 cm in the 6 benign schwannomas, and 12 cm in 1 malignant. The tumor margin was regular in all of the benign cases and irregular in the malignant one. The malignant case showed infiltration into the liver and duodenum. Four of the benign schwannomas showed a homogeneous, and 2 presented a heterogeneous pattern, while the malignant schwannoma was heterogeneous. On T1-weighted images, the benign schwannomas were hypointense in 4 cases, isointense in 1 and mixed in 1, while on T2-weighted images, they were hyperintense in 5 and mixed in 1. The malignant case showed mixed intensity on both T1- and T2-weighted images. On enhanced T1-weighted images, capsular, septal enhancement was noted in 2 cases, overall enhancement in 2, and, on Gd-dynamic images, late enhancement was shown. CONCLUSION: On MR imaging, primary retroperitoneal schwannomas show different signal intensity characteristics, including cystic degeneration. There are, however, no specific characteristics of these tumors.

Aged↗

PubMed1999

Synthesis of novel nucleotide analogues possessing a difluoromethylenephosphonato group. Evaluation of the inhibitory activity for purine nucleoside phosphorylase.

Novel nucleotide analogues 1-6 were prepared as "multi-substrate" analogue inhibitors for purine nucleoside phosphorylases (PNPs). The cyclopropane and the tetrahydrofuran moieties of the alkyl spacer connecting a nucleobase and difluoromethylene phosphonic acid were found to be effective for good inhibition of PNPs.

Actinomycetales↗

PubMed1999

Hepatic heme metabolism in rats with fever induced by interleukin 1beta.

We have recently reported that the content of hepatic cytochrome P450 (CYP) apparently decreased in fever model rats, which were created by repeated injection of recombinant human interleukin-1beta (rhIL-1beta) into the cerebroventricle. To make clear the biochemical mechanism of the decreased CYP content, we examined the effect of fever on the activities of hepatic enzymes involved in the biosynthetic and degradative pathways of heme. The activities of delta-aminolevulinic acid synthase, a rate-limiting enzyme in the heme biosynthesis, and porphobilinogen synthase in the liver of rhIL-1beta-induced fevered rat were significantly lower than those in the control, whereas the activity of heme oxygenase, a key enzyme in the heme-degradative pathway, markedly increased in the fevered rat. Moreover, the heme saturation of tryptophan 2,3-dioxygenase in the fevered rat liver was decreased to 43% of the control. These results indicate that fever diminishes the hepatic heme content by decreasing the heme biosynthesis and by accelerating the heme degradation. The deficiency of hepatic heme pool may be one of the main mechanisms that cause the impairment of CYP synthesis.

5-Aminolevulinate Synthetase↗

PubMed1998

Tumor necrosis factor-alpha-induced release of plasminogen activator inhibitor-1 from human umbilical vein endothelial cells: involvement of intracellular ceramide signaling event.

We have investigated the biochemical mechanism of tumor necrosis factor (TNF)-alpha-induced release of plasminogen activator inhibitor-1 (PAI-1) from human umbilical vein endothelial cells (HUVEC). Treatment of HUVEC with TNF-alpha for 3 h resulted in a 2. 8-fold increase in the PAI-1 release compared with control. The increase in PAI-1 release was accompanied by a 133% increase in the intracellular acidic sphingomyelinase (SMase) activity. High-performance liquid chromatographic (HPLC) analysis revealed that the intracellular ceramide levels increased to 126% of the control (P<0.05), but the contents of membranous ceramide remained unaltered. We have previously shown that a cell-permeable ceramide analog, N-acetylsphingosine (C2-ceramide) enhances the PAI-1 release from HUVEC. Here, N-acetylsphinganine (C2-dihydroceramide) was found to specifically suppress both C2-ceramide- and TNF-alpha-induced increase in PAI-1 release from HUVEC without affecting the control PAI-1 release. Treatment of HUVEC with staphylococcal SMase that may mimic the activation of the membranous neutral SMase also increased the PAI-1 release. The increase in PAI-1 release by this mechanism was suppressed by a cyclooxygenase inhibitor, aspirin, whereas the inhibitor did not affect TNF-alpha-induced increase in PAI-1 release. Taken together, these findings suggest that TNF-alpha prominently utilizes the lysosomal acidic SMase-ceramide signaling pathway in the induction of PAI-1 release from HUVEC.

Ceramides↗

PubMed1998

Partial purification and characterization of sphingosine N-acyltransferase (ceramide synthase) from bovine liver mitochondrion-rich fraction.

Sphingosine N-acyltransferase (ceramide synthase, E.C. 2.3.1.24) was solubilized from bovine liver mitochondrion-rich fraction with n-octyl beta-D-thioglucoside as the detergent and partially purified by sequential chromatography on columns of DE-32, shingosine affinity, and Sepharose CL-6B. The partially purified preparation migrated on SDS-polyacrylamide gel electrophoresis as two major protein bands of 62 and 72 kDa. The molecular mass of the enzyme estimated by gel filtration was 240-260 kDa, suggesting that the partially purified enzyme is present in a subunit form or simply has an aggregative nature. The specific activity of the final preparation for the condensation of sphingosine with stearoyl-CoA increased by 98.7-fold compared with the starting material. The optimal pH value for the ceramide synthesis was 7.5. The partially purified enzyme had an apparent Km of 146 microM and a Vmax of 11.1 nmol/min/mg protein for stearoyl-CoA. The Km and Vmax values toward sphingosine were 171 microM and 11.3 nmol/min/mg protein, respectively. Interestingly, sphinganine was also a good substrate for this enzyme, and the Km and Vmax values were 144 microM and 8.5 nmol/min/mg protein, respectively.

Acyl Coenzyme A↗

PubMed1998

Synthesis of 1,1-difluoro-5-(1H-9-purinyl)-2-pentenylphosphonic acids and the related methano analogues. Remarkable effect of the nucleobases and the cyclopropane rings on inhibitory activity toward purine nucleoside phosphorylase.

A series of 1,1-difluoro-5-(1H-9-purinyl)-2-pentenylphosphonic acids, (E)-2a,b and (Z)-2a,b, as well as the related methano analogues (+/-)-3a,b and (+/-)-4a,b were prepared for evaluation of their PNP inhibitory activities. The cyclopopane ring and the hypoxanthine residue were found to increase the profile of inhibitory activity. The IC50 and Ki values of difluoro¿(1R*,2S*)-2-[2-(6-oxo-6,9-dihydro-1H-9-purinyl)ethyl]cycl opropyl¿methylphosphonic acid (+/-)-3b toward PNP purified from Cellulomonas sp. were determined to be 70 nM and 8.8 nM, respectively.

Binding Sites↗

PubMed1998

Effect of interleukin 1 beta-induced fever on hepatic drug metabolism in rat.

1. A fever-induced model in rat was created by repeated injection of interleukin 1 beta (IL-1 beta) in the cerebroventricle and the influence of fever on hepatic drug metabolism was investigated. Fever apparently decreased the content of cytochrome P450 (CYP) and the activities of NADPH-ferrihaemoprotein reductase (fp2), aminopyrine N-demethylase, aniline hydroxylase, FAD-monooxygenase, p-nitrophenol UDP-glucuronosyl-transferase and glutathione S-transferase. Immunoblot analysis of the CYP isozymes indicated that CYP2C11 and CYP3A were extensively decreased in the IL-1 beta-induced fevered rat. 2. Repeated administration (5 days) of mefenamic acid in the fevered rat could not restore the activities of fp2, aminopyrine N-demethylase and aniline hydroxylase to control levels, although their hyperthermic state had been improved. The CYP content in the mefenamic acid-treated fevered rat was also lower than that in the control. 3. These findings suggest that fever impairs the hepatic drug-metabolizing capacity (both oxidation and some conjugations) and that the fever-induced impairments are partially retained, even if the hyperthermia has been offset by the administration of antipyretics.

Aminopyrine N-Demethylase↗

PubMed1997

Nail transfer: evolution of the reconstructive procedure.

Reconstruction of a missing or deficient nail is an interesting and challenging undertaking for plastic surgeons, but little has been published concerning this topic. In the past 23 years, from 1973 to 1995, we performed 24 operations for nail reconstruction in 19 patients. A free nail graft was used in 14 operations, and a vascularized nail flap was used in 10. Vascularized nail flaps were divided into three categories: long-pedicle vascularized nail flaps (3 nails), vascularized nail flaps supplied by arterial inflow from the venous system (termed venous flaps, 3 nails), and short-pedicle vascularized nail flaps (4 nails). In only one case of free nail graft did the grafted nail necrose secondary to infection. The other 23 nails (13 free nail grafts, 10 vascularized nail flaps) survived completely, and good nail growth was obtained. With progress in plastic surgery, reconstructive procedures for nails have changed. In this paper, we will report the evolution of our reconstructive procedure and current strategy of nail reconstruction.

Adult↗

PubMed1997

Synergistic anti-influenza virus A (H1N1) activities of PM-523 (polyoxometalate) and ribavirin in vitro and in vivo.

A Kegin-type polyoxometalate, PM-523, in combination with ribavirin, was tested for its therapeutic effectiveness against influenza virus (FluV) A (H1N1) infection in tissue culture and in mice. PM-523 [(PriNH3)6H [PTi2W10O38(O2)2] x H2O, where Pri is isopropanol] and ribavirin individually inhibited FluV A-induced cytopathic effects in Madin-Darby canine kidney (MDCK) cells at median effective concentrations (EC50s) of 30 and 34 microM, respectively, and at 70% effective concentrations (EC70s) of 48 and 72 microM, respectively. On the other hand, a combination of PM-523 and ribavirin at a ratio of 1:16 exhibited lower EC50s and EC70s than each compound used singly, and combination indices were less than 1. A wide range of combinations of PM-523 and ribavirin at ratios of from 1:128 to 1:1 exhibited additive or synergistic anti-FluV effects in MDCK cells. When these compounds were tested for their anti-FluV A activities in vivo by aerosol exposure of mice which had been infected with a lethal dose of FluV A by an intranasal route, a 1:16 combination of PM-523 and ribavirin was found to have a significantly better therapeutic effect than a single dose of either compound used singly with respect to both the survival rate of the mice and the virus titer in the lungs of the infected mice. PM-523 was effective for the treatment of experimental FluV infection, and in combination with ribavirin, PM-523 exhibited enhanced anti-FluV effects in vitro and in vivo compared with the effect of PM-523 alone.

Animals↗

PubMed1997

Cloning of genes coding for L-sorbose and L-sorbosone dehydrogenases from Gluconobacter oxydans and microbial production of 2-keto-L-gulonate, a precursor of L-ascorbic acid, in a recombinant G. oxydans strain.

We have purified L-sorbose dehydrogenase (SDH) and L-sorbosone dehydrogenase (SNDH) from Gluconobacter oxydans T-100 that showed an ability to convert D-sorbitol to 2-keto-L-gulonate (2-KLGA). A genomic library of Gluconobacter oxydans T-100 was screened with a probe, a 180-bp PCR product which was obtained from degenerate oligodeoxyribonucleotides based on the elucidated sequence of the purified SDH (used as primers) and the genomic DNA of G. oxydans T-100 (used as a template). From sequencing of the DNA from a clone positive to the probe, the SNDH and the SDH were estimated to be coded in sequential open reading frames with 1,497 and 1,599 nucleotides, respectively, which was confirmed by expression of the DNA in Escherichia coli that showed both enzymatic activities. The DNA was introduced to a shuttle vector which was prepared from a plasmid of G. oxydans T-100 and pHSG298 to obtain an expression vector designated pSDH155. The production of 2-KLGA by pSDH155 in G. oxydans G624, an L-sorbose-accumulating strain, was improved to 230% compared to that of G. oxydans T-100. Chemical mutation of the host strain to suppress the L-idonate pathway and replacement of the original promoter with that of E. coli tufB resulted in improving the production of 2-KLGA. Consequently, high-level production from D-sorbitol to 2-KLGA (130 mg/ml) was achieved by simple fermentation of the recombinant Gluconobacter.

Acetobacteraceae↗

PubMed1997

Inhibitory effect of oversulfated fucoidan on tube formation by human vascular endothelial cells.

Fucoidan is a sulfated poly(L-fucopyranose) present in brown marine algae. In this study, we examined the effect of native and chemically oversulfated fucoidans (NF and OSF) on the tube structure formation by human umbilical vein endothelial cells (HUVEC) on the basement membrane preparation, Matrigel. Unlike NF, OSF significantly decreased the tube formation: maximal inhibition (50% of control) was obtained with 25 micrograms/ml. The OSF effect was mediated, at least in part, through the inhibition of HUVEC migration, as determined by the ability to block chemotaxis in a Transwell chamber assay. Quantitative immunoreactive assays for tissue-type plasminogen activator (t-PA) and plasminogen activator inhibitor-1 (PAI-1) in the culture media indicated that OSF (25 micrograms/ml) increased the accumulation of PAI-1 antigen, but not of t-PA antigen, 2.7-fold compared with control. The release of both antigens by HUVEC was slightly affected by the addition of NF. Determination of the media levels of type IV collagenase activity and tissue inhibitor of metalloproteinase-1 (TIMP-1) antigen showed that OSF (25 micrograms/ml) decreased the collagenolytic activity by 50% compared to the control, without alteration of the TIMP antigen level. However, the collagenase inhibition by OSF was not observed in an assay system using purified enzyme. NF had no effect on collagenase activity or TIMP-1 antigen levels. These results indicate that the introduction of sulfate groups into NF enables it to effectively inhibit the formation of capillary-like structures by HUVEC on Matrigel by reducing the basement membrane destruction and cell migration. It is involved as at least one of the mechanisms by which the OSF-induced increase in HUVEC PAI-1 decreases plasmin formation and suppresses the following pro-collagenase activation.

Cell Adhesion↗

PubMed1997

Effect of 15-hydroperoxyeicosatetraenoic acid on the fibrinolytic factor release and the antithrombin binding of vascular endothelial cells.

15-Hydroperoxyeicosatetraenoic acid (15-HPETE), an arachidonate lipoxygenase product, is reported to induce severe endothelial injury. In this study, we examined the effect of 15-HPETE on the release of tissue-type plasminogen activator (t-PA) and plasminogen activator inhibitor-1 (PAI-1) from cultured human umbilical vein endothelial cells (HUVEC). The addition of 15-HPETE to the serum-free medium reduced the release of t-PA antigen from HUVEC, while the release of PAI-1 antigen was significantly enhanced. However, treatment of the cultured HUVEC with alpha-tocopherol or nordihydroguaiaretic acid completely suppressed the 15-HPETE-induced change in t-PA and PAI-1 antigen release. 15-Hydroxyeicosatetraenoic acid (15-HETE) had no effect on the release of either antigen from cultured HUVEC. The HUVEC surfaces exposed to 15-HPETE decreased the potency for binding antithrombin III. In a reconstituted system with heparin and phosphatidylcholine, 15-HPETE decreased the ability of heparin to inactivate thrombin activity. These results suggest that the fibrinolytic factor release and the antithrombin binding of vascular endothelial cells are impaired by the attack of 15-HPETE, and that the presence of antioxidants prevents the injurious action of lipid hydroperoxide.

Antioxidants↗

PubMed1997

Two molecular species of oxytocinase (L-cystine aminopeptidase) in human placenta: purification and characterization.

Two different forms of oxytocinase (L-cystine aminopeptidase, CAP; EC 3.4.11.3) were purified from the 9000 g and 105000 g precipitate fractions of human placenta homogenate by sequential chromatography on columns of hydroxyapatite, DE-32, nickel ion affinity, and Sephadex G-200. One species (CAP-I) purifed from the mitochondrial/lysosomal fraction migrated on sodium dodecyl sulfate (SDS)-polyacrylamide gel electrophoresis with an apparent molecular mass of 61 kDa; the other (CAP-II) from the microsomal fraction was composed of two subunits with molecular masses of 56 and 40 kDa. The molecular masses of CAP-I and CAP-II estimated by gel filtration were 64 and 97 kDa, respectively. The specific activities of the two species for S-benzyl-L-cysteine p-nitroanilide increased by 357- (for CAP-I) and 139-fold (for CAP-II) compared with the starting preparations. The optimal pH values toward the artificial substrate were approx. 7.4-8.0 for CAP-I and 6.8-8.0 for CAP-II. The Km and Vmax values toward oxytocin were 5.6 microM and 23.4 micromol/h/mg protein for CAP-I, and 38 microM and 15.6 micromol/h/mg protein for CAP-II. Both enzymes were inhibited by the metal-chelating agents, EDTA and o-phenanthroline, whereas they were specifically activated by addition of Co2+: CAP-I was more sensitive to these reagents than CAP-II. L-Methionine strongly inhibited CAP-I, while CAP-II activity was only slightly affected. CAP-II was more sensitive to amastatin than CAP-I. Thus, the two enzymes are quite distinct in their molecular nature and biochemical properties. They may play a regulatory role in the metabolism of oxytocin and other biologically active peptides in intact placenta.

Cystinyl Aminopeptidase↗

PubMed1996

Vascular endothelial cell monolayer formed on membrane filter potentiates the defense against tumor cell invasion by treatment with brefeldin A.

We constructed vascular endothelial cell monolayer on a fibronectin-coated filter in a Boyden chamber and assessed the ability of 3 LL cells to penetrate through the artificial blood vessel wall. The defense of endothelial cell monolayers against the tumor cell invasion was greatly potentiated by their pretreatment with 5 or 10 micrograms/ml of brefeldin A (BFA) for 1 h (52% or 28% of control invasion). Treatment of the endothelial cell monolayers with BFA resulted in an increase in the release of inhibitory material(s) against urokinase-type plasminogen activator (u-PA) activity of 3 LL cells. Parallel experiments with the cultured endothelial cells and BFA indicated that the fungal metabolite enhanced a rate of accumulation of plasminogen activator inhibitor-1 (PAI-1) antigen, but not of tissue-type plasminogen activator antigen in the medium. The BFA-induced enhancement of PAI-1 antigen release was accompanied with the increased accumulation of the extracellular (membrane/matrix-bound) and intracellular PAI-1 antigen (219% of control at 24 h). These results suggest that BFA can strengthen the defense of vascular endothelium against tumor-cell invasion by enhancing the release and accumulation of PAI-1, which plays a critical role in the regulation of the u-PA-plasmin-collagenase activation cascade.

Brefeldin A↗

PubMed1995

Sphingomyelinase and cell-permeable ceramide analogs increase the release of plasminogen activator inhibitor-1 from cultured endothelial cells.

We investigated the effect of exogenous staphylococcal sphingomyelinase (SMase) on the release of tissue-type plasminogen activator (t-PA) and plasminogen activator inhibitor-1 (PAI-1) from cultured human umbilical vein endothelial cells (HUVEC). Addition of SMase (2 units/ml) to the culture medium induced an approx. 15-fold increase in the extracellular level of PAI-1 antigen at 3 h. No significant increase in the level of t-PA antigen was detected. Treatment of HUVEC with SMASE (2 units/ml) for 3 h resulted in a significant decrease in the cellular sphingomyelin (SM) level, accompanied by a corresponding increase in the ceramide level. Cell-permeable ceramide analogs also enhanced the release of PAI-1 from cultured HUVEC in concentration- and time-dependent manners. A 6-fold increase in PAI-1 antigen level was observed after incubation for 3 h with 10 microM N-acetylsphingosine. Similar effect was noted as early as 2 h with 10 microM N-hexyanoylsphingosine. Addition of sphingosine failed to affect the release of PAI-1 from cultured HUVEC, indicating that the effects of ceramide analogs were independent of sphingosine generation. Pretreatment with cycloheximide or actinomycin D abated the response of HUVEC to N-acetylsphingosine in the increased levels of both extracellular and intracellular PAI-1. These results suggest that ceramide, generated via "SM cycle", acts as a lipid mediator of PAI-1 release from vascular endothelial cells, and may contribute to a better understanding of the pathogenesis of the PAI-1-associated thrombotic disorders.

Cell Membrane Permeability↗

PubMed1995

Oversulfated fucoidan and heparin suppress endotoxin induction of plasminogen activator inhibitor-1 in cultured human endothelial cells: their possible mechanism of action.

Plasminogen activator inhibitor-1 (PAI-1) is a primary endogenous inhibitor of tissue-type plasminogen activator (t-PA). In this study, we examined the effects of oversulfated fucoidan (OSF) derivatives and heparin on lipopolysaccharide (LPS)-induced release of PAI-1 antigen from cultured human umbilical vein endothelial cells (HUVEC). Addition of LPS (10 micrograms/ml) enhanced the release of PAI-1 by HUVEC but not of t-PA antigen. At 18 h, a 2.4-fold increase in the extracellular PAI-1 level was observed. The increased PAI-1 level was reduced to control level by the simultaneous addition of 10 micrograms/ml of OSF or heparin. The suppressive effect of native fucoidan was negligible. We also examined the molecular size effect of OSF, using 10-20, 20-40, and 40-60 kDa fragments. The result indicated that these fragments were effective as well as the 100-130 kDa form of OSF, hence suggesting an important role of the degree of sulfation. Interleukin-1 beta (IL-1 beta) is a potent inducer of PAI-1 in cultured HUVEC. Heparin, OSF, and its fragments did not suppress the IL-1 beta-induced release of PAI-1 antigen. Treatment of HUVEC with heparitinase or monoclonal antibody against heparin sulfate proteoglycan (HSPG) resulted in a complete loss of its ability to enhance PAI-1 release in response to LPS stimulation, while the chondroitinase ABC treatment hardly affected the PAI-1 production. These results suggest that HSPG is involved in the initial binding of LPS to HUVEC. The suppressive effects of OSF and heparin on LPS-induced PAI-1 release may result from the inhibition of LPS binding to the cell surface HSPG.

Antibodies, Monoclonal↗