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Biomedical subjects

S Urano

Publications and source records attributed to S Urano.

At least 37 records · Page 2Linked to original sources
PubMed1995

[Evaluation of surgical treatment for bone metastatic lesion in renal cell carcinoma].

Ten renal cell carcinoma (RCC) patients with bone metastatic lesions were treated in the Kyoto Prefectural University of Medicine between January, 1977, and December, 1992. Surgical treatment for the metastatic lesion was performed on 4 patients, while conservative treatment was performed on the other 6 patients. Surgical treatment made the patients painless consecutively, resulting in higher activities of daily life. However, recurrence of RCC developed in all the cases between 2 and 7 years later. Surgical treatment for the metastatic lesion was considered to be only a palliative therapy for RCC with bone metastasis and the indication should be limited to patients expected to have a good prognosis.

Adult↗
PubMed1995

[Benign hemorrhagic renal cyst diagnosed by endoscopic biopsy: a case report].

A case of benign renal hemorrhagic cyst in a 73-year-old man is reported. Ultrasonography, computed tomography and magnetic resonance imaging revealed a solid mass in the left renal cyst. Percutaneous puncture of left renal cyst was carried out followed by endoscopic biopsy of the intracystic masses. Specimens showed no malignancy. As we could not rule out malignancy, left partial nephrectomy was performed. The surgical specimen was free from malignancy by pathological examination. Thus endoscopic biopsy of intracystic tumor indicated the correct diagnosis.

Aged↗
PubMed1994

Determination of rhoifolin and daidzin in human plasma by high-performance liquid chromatography.

A method for determining flavonoids in human plasma is presented for application to pharmacokinetic studies of two flavonoids, rhoifolin and daidzin. Isocratic reversed-phase high-performance liquid chromatography (HPLC) was used with genistin as an internal standard and solid-phase extraction using a Sep-Pak C18 cartridge. The mobile phases were acetonitrile-0.1 M ammonium acetate solution (20:80, v/v) for rhoifolin and methanol-0.1 M ammonium acetate solution (33:67, v/v) for daidzin. The detection limits on-column were 2 ng for rhoifolin and 0.5 ng for daidzin.

Acetates↗
PubMed1994

Age-related changes in the metabolism of acetylated low-density lipoproteins by peritoneal macrophages from C57BL/6CrScl mice.

Macrophages are major precursors of foam cells in atherosclerotic lesions. Acetylated low-density lipoproteins (acetyl LDL) taken up by macrophages through scavenger receptors are degraded by lysosomes and the released cholesterol is re-esterified, leading to foam cell formation. The ability of resident peritoneal macrophages from C57BL/6CrScl mice to form foam cells in relation to the donor age was assessed by the cholesterol esterification and the metabolism of acetyl LDL. The incorporation of 14C-oleate (complexed to albumin) into cellular cholesteryl esters in the presence of acetyl LDL (100 micrograms/ml) was significantly greater in macrophages from senescent mice (24-25 months) than in cells from young (3-4 months) mice (p < .001). The degradation and cellular association of acetyl LDL by macrophages from senescent mice were significantly greater than macrophages from mature mice, (p < .001 and p < .01, respectively), whereas the binding of acetyl LDL was similar in peritoneal macrophages from mature and senescent mice. These results suggest that the uptake and degradation of acetyl LDL, and the re-esterification by macrophages increase with advancing age and that the ability of macrophages to form foam cells increases with aging. The enhanced ability of senescent macrophages to form foam cells might contribute to the development and progression of atherosclerosis related to the aging process.

Aging↗
PubMed1993

Mobility and molecular orientation of vitamin E in liposomal membranes as determined by 19F NMR and fluorescence polarization techniques.

To elucidate the molecular orientation and mobility of alpha-tocopherol (vitamin E) in membranes, 19F nuclear magnetic resonance (NMR) was applied. In bilayer phosphatidylcholine (PC) liposomes, 19F NMR spin-spin relaxation times (T2) of 19F-labeled methyl groups on either the chromanol moiety or the isoprenoid side chain of alpha-tocopherol were significantly decreased compared to those for alpha-tocopherol in solution (CDCl3), suggesting that the vitamin E molecule exists in the lipid core of membranes and that its motional freedom is significantly restricted. The difference in T2 values between the solution state and PC liposomes was greatest for the 5a-CF3 on the chromanol moiety compared with other methyl groups on the isoprenoid side chain. Hence, it is thought that the chromanol moiety of alpha-tocopherol may fit tightly near the surface of the membrane because of its hydrophilicity. When Pr3+ was added to the liposomal suspension, the intensity of the NMR signal for 5a-CF3 changed faster than those of the other methyl groups. When the surface of the liposomal membranes was positively charged using stearyl amine, the mobility of the 5a-methyl group, expressed as the correlation time (tau c), was quite similar to that in negatively charged membranes. These results indicate that the chromanol moiety of alpha-tocopherol may orient near the membrane surface, and that the hydroxyl group may be hydrogen bonded to the ester carbonyl of PC. For further confirmation of this conclusion, time-dependent changes in the fluidity of liposomes caused by the addition of Pr3+ were measured at the surface and inner region of liposomal membranes using a fluorescence polarization technique. The fluidity increased in the surface region and decreased in the inner region of liposomes containing alpha-tocopherol. These results show that when praseodymium ions may pass through the liposomal membrane, the hydrogen bonds between alpha-tocopherol and the ester carbonyl of PC may be broken, leading to the formation of an alpha-tocopherol-Pr3+ complex, thus causing the fluidity to increase. Based on the findings obtained, mobility and molecular orientation of vitamin E in membranes are proposed.

Fluorescence Polarization↗
PubMed1992

Vitamin E: inhibition of retinol-induced hemolysis and membrane-stabilizing behavior.

For the elucidation of the mechanism of membrane stabilization by vitamin E, the effects of alpha-tocopherol and its model compounds on either retinol-induced hemolysis of rabbit erythrocytes or the permeability and fluidity of liposomal membranes have been studied. Retinol-induced rabbit erythrocyte hemolysis has been found not to be caused by the oxidative disruption of erythrocyte membrane lipids initiated by retinol oxidation, but rather to arise from physical damage of the membrane micelle induced by penetration of retinol molecules. In suppressing hemolysis, alpha-tocopherol was more effective than other naturally occurring tocopherols. alpha-Tocopheryl acetate, nicotinate, and 6-deoxy-alpha-tocopherol were more effective than alpha-tocopherol itself. The inhibitory effects of alpha-tocopherol model compounds having side chains with at least two isoprene units or a long straight chain instead of the isoprenoid side chain were similar to those of alpha-tocopherol. These data suggest that for protection of membranes against retinol-induced damage, the hydroxyl group of alpha-tocopherol is not critical, but rather the chroman ring, three methyl groups on the aromatic ring, and the long side chain are necessary. To verify the mechanism of the inhibitory effect on hemolysis, not only the effect of vitamin E and its model compounds on the membrane permeability and fluidity, but also the mobility of alpha-tocopherol molecule in membranes has been investigated using bilayer liposomes as the model membranes. Addition of alpha-tocopherol to membranes produced a greater decrease in the permeability and fluidity of rat liver phosphatidylcholine liposomes compared with egg yolk phosphatidylcholine liposomes. In dipalmitoylphosphatidylcholine liposomes, however, alpha-tocopherol was less effective, that is, the more unsaturated the lipids, the more they interact with alpha-tocopherol. 2,2,5,7,8-Pentamethyl-6-chromanol with no isoprenoid side chain and phytol without the chromanol moiety had no effect. The measurement of 13C NMR relaxation times revealed that the mobility of methyl groups on the aromatic ring of alpha-tocopherol in membranes is significantly restricted. In contrast, the methyl groups at positions 4'a and 8'a on the isoprenoid side chain have high degrees of motional freedom in the lipid core of membranes. Furthermore, it was found that alpha-tocopherol in membranes interacts with chromate ions added as potassium chromate outside the membranes, resulting in an increase in membrane fluidity. These results are compatible with those of the inhibitory effect on retinol-induced erythrocyte hemolysis. On the basis of the results obtained here, a possible mechanism for membrane stabilization by vitamin E is proposed.

Animals↗
PubMed1992

Progesterone regulation of plasminogen activator inhibitor 1 (PAI-1) antigen and mRNA levels in human endometrial stromal cells.

Plasminogen activator activity decreases in the endometrium in the secretory phase of the menstrual cycle. This is partly due to decreased release of urokinase plasminogen activator in response to progesterone. Plasminogen activator inhibitor type 1 (PAI-1) is an efficient inhibitor of both tissue-type and urokinase-type plasminogen activators, and may therefore be instrumental for the control of plasminogen activation. In this study we examined the effects of steroid hormones on PAI-1 release and PAI-1 mRNA levels in primary cultures of human endometrial stromal cells. In these cells the secretion of PAI-1 was increased by progesterone in a dose and time dependent way, but was not affected by estradiol. The progesterone induction of PAI-1 secretion was preceded by a 7-8 fold increase of the steady state level of PAI-1 mRNA in the cells, suggesting that progesterone activates PAI-1 gene expression. Cultured endometrial glandular epithelial cells were found to release only insignificant amounts of PAI-1 with or without hormone treatment. The effect of progesterone on endometrial stromal cells was mimicked by DH-testosterone. However, while the response to progesterone was completely blocked by ZK112993, a potent antagonist of the progesterone receptor, the response to DH-testosterone was partially blocked by ZK112993, and partially by OH-flutamide, a potent antagonist of the androgen receptor. This suggests that a secretory response on PAI-1 expression is mediated via androgen receptors in endometrial tissue.

Adult↗
PubMed1992

Location and dynamics of alpha-tocopherol in model phospholipid membranes with different charges.

Studies were made on the position and dynamics of the OH-group of alpha-tocopherol in phospholipid membranes. There was no difference in the spin-lattice (T1) relaxation times at the 5a-position of alpha-tocopherol labeled with 13C- or C19F3-determined from the nuclear magnetic resonance (NMR) spectra of liposomes positively charged with stearylamine (SA) and negatively charged with dicetylphosphate (DCP). The zeta-potentials of egg yolk phosphatidylcholine (EYPC) liposomes with and without SA or DCP were not affected by incorporation of 20 mol% alpha-tocopherol, though incorporation of 10 mol% ascorbyl-palmitate decreased the zeta-potentials of EYPC and EYPC-SA liposomes. The P==O stretching band (1235 cm-1) of the phosphate group and C==O stretching band (1734 cm-1) of the acyl ester linkage in dimyristoylphosphatidylcholine (DMPC) liposomes, measured by Fourier transform-infrared (FT-IR) spectroscopy, were not changed by incorporation of alpha-tocopherol. These results suggest that no specific interaction occurred between the OH-group of alpha-tocopherol and the polar interfacial region of the bilayer. The dynamic quenching effects of n-(N-oxy-4,4'-dimethyloxazolidine-2-yl)stearic acids (n-NSs) on the intrinsic fluorescence of alpha-tocopherol were in the order 5-NS > 7-NS = 12-NS > 16-NS. Acrylamide, a water-soluble fluorescence quencher with a very low capacity to penetrate through phospholipid bilayers, had very low quenching efficiency. These results indicate that the bulk of the chromanol moiety of alpha-tocopherol is located in a position close to that occupied by the nitroxide group of 5-NS in the membranes and is poorly exposed at the membrane surface.(ABSTRACT TRUNCATED AT 250 WORDS)

Electrochemistry↗
PubMed1992

Plasminogen activators in the human endometrium, cellular origin and hormonal regulation.

Endometrial tissue explants in culture were found to release urokinase-type plasminogen activator (u-PA) and tissue-type plasminogen activator (t-PA). In order to identify their cellular origin and possible hormonal regulation, enriched cultures of glandular epithelial cells and stromal cells were prepared from fresh endometrium, and the cultures treated with hormones. Both epithelial and stromal cell cultures were found to secrete u-PA and t-PA. Treatment of epithelial cell cultures with oestradiol, progesterone and DH-testosterone had no effect on the secretion of t-PA or u-PA. In stromal cell cultures, on the other hand, the secretion of u-PA was significantly reduced after treatment with progesterone, whereas oestradiol and DH-testosterone had no effect. This reduction of u-PA antigen in the tissue culture medium did not result from a reduction of the relative level of u-PA mRNA in the cells, suggesting that the synthesis of u-PA was not reduced. Alternatively, an increased clearance of u-PA by the cells from the medium may explain the reduction. This in vitro observation probably reflects the in vivo reduction of u-PA in endometrial secretion during the secretory phase.

Adult↗
PubMed1991

Vitamin E and the susceptibility of erythrocytes and reconstituted liposomes to oxidative stress in aged diabetics.

A remarkable increase in the permeability of erythrocyte ghosts and liposomal membranes composed of erythrocyte lipids from aged diabetics was revealed by measuring [14C]glucose leakage. There were no significant differences in the contents of free cholesterol or phospholipids, or in the cholesterol/phospholipid ratio between diabetic and normal erythrocyte membranes, but significantly higher amounts of unsaturated fatty acids, arachidonic acid and docosahexaenoic acid were observed in the erythrocyte membranes of diabetics. Reconstituted liposomes prepared from aged diabetic erythrocyte lipids were highly susceptible to superoxide-induced oxidative stress. Vitamin E was highly effective in suppressing the peroxidative lysis of liposomes composed of diabetic erythrocyte lipids. The effect of superoxide dismutase (SOD) on the inhibition of peroxidation of unsaturated lipids within liposomal membranes was less than that of vitamin E.

Aged↗
PubMed1990

Stopped-flow kinetic study of the regeneration reaction of tocopheroxyl radical by reduced ubiquinone-10 in solution.

Kinetic study of the reaction between tocopheroxyl (vitamin E radical) and ubiquinol-10 (reduced ubiquinone, n = 10) has been performed. The rates of reaction of ubiquinol with alpha-tocopheroxyl 1 and seven kinds of alkyl substituted tocopheroxyl radicals 2-8 in solution have been determined spectrophotometrically, using a stopped-flow technique. The result shows that the rate constants decrease as the total electron-donating capacity of the alkyl substituents on the aromatic ring of tocopheroxyls increases. For the tocopheroxyls with two alkyl substituents at ortho positions (C-5 and C-7), the second-order rate constants, k1, obtained vary in the order of 10(2), and decrease predominantly, as the size of two ortho-alkyl groups (methyl, ethyl, isopropyl and tert-butyl) in tocopheroxyl increases. On the other hand, the reaction between tocopheroxyl and ubiquinone-10 (oxidized ubiquinone) has not been observed. The result indicates that ubiquinol-10 regenerates tocopherol by donating a hydrogen atom of the 1-OH and/or 4-OH group to the tocopheroxyl radical. For instance, the k1 values obtained for alpha-tocopheroxyl are 3.74 x 10(5) M-1.s-1 and 2.15 x 10(5) M-1.s-1 in benzene and ethanol solution at 25 degrees C, respectively. The above reaction rates, k1, obtained were compared with those of vitamin C with alpha-tocopheroxyl reported by Packer et al. (k2 = 1.55 x 10(6) M-1.s-1) and Scarpa et al. (k2 = 2 x 10(5) M-1.s-1), which is well known as a usual regeneration reaction of tocopheroxyl in biomembrane systems. The result suggests that ubiquinol-10 also regenerates the tocopheroxyl to tocopherol and prevents lipid peroxidation in various tissues and mitochondria.

Antioxidants↗
PubMed1990

Relationships between euglobulin clot lysis time and the plasma levels of tissue plasminogen activator and plasminogen activator inhibitor 1.

The relationships between tissue plasminogen activator (tPA), its fast acting inhibitor (PAI-1) and euglobulin clot lysis time (ELT) were investigated with healthy volunteers' plasma. Turbidimetric clot lysis assay by the microtiter plate reader was utilized for ELT with a slight modification. Both tPA and PAI-1 showed the significant correlation with ELT. tPA had a significantly positive, not negative, correlation with ELT (R = 0.387, p less than 0.001). Higher correlation coefficients (R = 0.580, p less than 0.001 and R = 0.599, p less than 0.001) were obtained between ELT and total PAI-1 or free PAI-1 than tPA or tPA-PAI-1 complex (R = 0.427, p less than 0.001). The positive correlation was also obtained between tPA and PAI-1. These data suggest that PAI-1 is a highly important factor for ELT, especially, the amounts of free PAI-1 being the key factor to determine the ELT, which can represent the potential activity of the fibrinolytic system.

Adult↗
PubMed1990

Synthesis, purification, and properties of a peptide that enhances the activation of human [Glu1]plasminogen by tissue plasminogen activator and retards fibrin polymerization.

Solid phase synthesis of the hexapeptide, GPRVVE, which represents the amino terminal six amino acids of the alpha-chain of human fibrin, yielded a product that contained a modified glutamic acid. The nature of the modification was established as the Friedel-Crafts acylation product of the peptide and anisole, the latter reagent employed in the HF deblocking step. The anisoylated peptide selectively enhanced the activation rate of native [Glu1]plasminogen by recombinant tissue plasminogen activator, accelerated clot lysis, and retarded the polymerization of nascent fibrin.

Amino Acid Sequence↗
PubMed1990

Membrane stabilizing effect of vitamin E: existence of a hydrogen bond between alpha-tocopherol and phospholipids in bilayer liposomes.

In order to elucidate the existence of a hydrogen bond between alpha-tocopherol and phospholipids in bilayer liposomes, the effects of the presence or absence of alpha-tocopherol or its acetate on either the permeability of liposomes to chromate ions or the fluidity of liposomes composed of the different kinds of lecithin [egg yolk phosphatidylcholine (EPC), 1-oleoyl-2-palmitoylphosphatidylcholine (OPPC), or 1-O-oleyl-2-O-palmitoylphosphatidylcholine (OPPCE)] were examined. From the results obtained, it was concluded that the hydroxyl group of alpha-tocopherol is hydrogen bonded to the carbonyl group of a fatty acid ester in the phospholipids of bilayer liposomes in order to retain alpha-tocopherol molecule in the space close to the surface of membranes formed by the unsaturated fatty acid moiety of phospholipids.

Chromates↗
PubMed1989

Stimulation by fibrinogen of the amidolytic activity of single-chain tissue plasminogen activator.

The amidolytic steady-state kinetic properties of a series of recombinant tissue plasminogen activators (rt-PA) have been examined in the presence and absence of the positive effectors fibrinogen (Fg) and native soluble (des-A)-fibrin (sFn). Two-chain (tc) native rt-PA displayed a Km value of 0.50 mM and a kcat value of 13.2 s-1 toward the substrate, H-D-Ile-Pro-Arg-p-nitroanilide (S2288) at 37 degrees. When these same assays were conducted in the presence of Fg or sFn, the Km and kcat values remained essentially the same. On the other hand, the activity of single-chain (sc) rt-PA was significantly increased in the presence of Fg or sFn, by approximately 3.4- to 4-fold, due to alterations in both the Km and kcat of the reaction. Similar results were obtained with rt-PA deletion variants, obtained by site-directed mutagenesis. With rt-PA domain-deletion derivatives, consisting of kringles 1 (K1)-2 (K2)-protease (P), and K2-P, the amidolytic activities of the scrt-PA preparations were significantly stimulated (2.0- to 2.5-fold) by Fg and sFn, a property not shared by the corresponding tcrt-PA. On the other hand, neither the single- nor two-chain derivatives of a deletion mutant containing only the finger (F)-growth factor (E)-P domains displayed stimulation by Fg or sFn, results suggestive of the importance of the K2 region in the observed Fg- and Fn-induced stimulations rt-PA amidolytic activity. With one strategically important derivative, a molecule containing the amino acid replacement, Cys264----Gly [(Cys264----Gly)-rt-PA], a change resulting in the loss of covalent attachment of the heavy and light chains of tcrt-PA, the amidolytic activities of neither the single-chain nor the two-chain form of the molecule were stimulated by the presence of the above two positive effectors. With the single-chain form of this same derivative, the kcat of the reaction was extremely low (1.5 s-1), but increased to approximately 50.5 s-1 for the two-chain form, this latter value being nearly 4-fold higher than that of any of the wild-type recombinant rt-PA preparations examined. This suggests that the latent heavy chain of rt-PA inhibits the amidolytic activity found in the trypsin-like P domain.(ABSTRACT TRUNCATED AT 250 WORDS)

Amides↗
PubMed1989

Plasmin-mediated fibrinolysis by variant recombinant tissue plasminogen activators.

A rapid and quantitative fibrinolytic assay has been used to measure the overall activity of a recombinant tissue plasminogen activator (rTPA) preparation for dissolution of a fibrin clot by its ability to activate [Glu1]plasminogen (containing glutamic acid at position 1) to plasmin. A standard curve constructed for wild-type two-chain rTPA that contains, from the amino terminus, the finger (F)-growth factor (E)-kringle 1 (K1)-kringle 2 (K2)-serine protease (P) domains was used to assess the overall fibrin-dissolving abilities of variant recombinant molecules. Two-chain deletion mutants lacking the E domain, the F-E domains, the F-E-K1 domains, and the K1-K2 domains yielded activities ranging from 22% to 35% of the overall activity of wild-type two-chain rTPA, suggesting that both the K2 and F domains are individually responsible for a portion of the function of the molecule. Comparison of variant molecules containing F-K1-K2-P and F-K2-K2-P domains showed that the latter variant possessed a 4-fold higher activity (1.4-fold greater than that of wild-type two-chain rTPA), indicating that, for the activity measured, the presence of K2 leads to a greater effectiveness than that of K1. A plasmin cleavage-resistant mutant (Arg-275----Ser) has been used to assess possible differences in one- and two-chain rTPA in this overall activity, the former displaying 86% of the activity of the latter, suggesting that such differences are indeed small. Finally, the proper covalent attachment of the light and heavy chains of two-chain rTPA are very important to its overall fibrinolytic activity, since replacement of Cys-264 with glycine and concomitant disruption of one of the covalent attachment sites of the two chains provides a variant of rTPA with less than 2% of the activity of the wild-type two-chain molecule. The effector molecule, epsilon-amino hexanoic acid (epsilon Ahx; epsilon-aminocaproic acid), inhibits the overall fibrinolytic effect of rTPA in this system, with an effective Ki of approximately 1.5 mM. Its efficacy, as measured by the Ki, is independent of the presence of the epsilon Ahx binding regions of plasminogen and rTPA and is similar to the efficacy obtained when urokinase was the activator in place of wild-type two-chain rTPA or when activation of plasminogen was bypassed as a result of provision of preformed plasmin to the assay. The results suggest that in the overall clot lysis system, an important epsilon Ahx binding site may exist on fibrin that inhibits its dissolution by plasmin.

Biological Assay↗
PubMed1988

Oxidative hemolysis of erythrocytes and its inhibition by free radical scavengers.

The oxidative hemolysis of rabbit erythrocytes induced by free radicals and its inhibition by chain-breaking antioxidants have been studied. The free radicals were generated from either a water-soluble or a lipid-soluble azo compound which, upon its thermal decomposition, gave carbon radicals that reacted with oxygen immediately to give peroxyl radicals. The radicals generated in the aqueous phase from a water-soluble azo compound induced hemolysis in air, but little hemolysis was observed in the absence of oxygen. Water-soluble chain-breaking antioxidants, such as ascorbic acid, uric acid, and water-soluble chromanol, suppressed the hemolysis dose dependently. Vitamin E in the erythrocyte membranes was also effective in suppressing the hemolysis. 2,2,5,7,8-Pentamethyl-6-chromanol, a vitamin E analogue without phytyl side chain, incorporated into dimyristoylphosphatidylcholine liposomes, suppressed the above hemolysis, but alpha-tocopherol did not suppress the hemolysis. Soybean phosphatidylcholine liposomes also induced hemolysis, and a lipid-soluble azo initiator incorporated into the soybean phosphatidylcholine liposomes accelerated the hemolysis. The chain-breaking antioxidants incorporated into the liposomes were also effective in suppressing this hemolysis.

Animals↗