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Biomedical subjects

T Niwa

Publications and source records attributed to T Niwa.

At least 55 records · Page 3Linked to original sources
PubMed2000

Mass-spectral analysis of human interferon-gamma and chloramphenicol acetyltransferase I produced in two Escherichia coli strains.

Recombinant human interferon-gamma and chloramphenicol acetyltransferase I were isolated from two Escherichia coli strains, E. coli LE329 and E. coli XL1-blue and characterized by electrospray ionization mass spectrometry (ESI-MS). The ESI-MS analysis showed higher masses in comparison with the theoretically calculated for both proteins as well as unexpected molecular heterogeneity. The ESI-MS spectral patterns of the proteins depended on the host strain used and were more heterogenous for the proteins isolated from E. coli LE392. One of the proteins (human interferon-gamma obtained from E. coli XL1-blue) was further subjected to BrCN cleavage. The ESI-MS analysis of the polypeptide mixture revealed shift in the molecular mass for two peptides including the last 26 amino acids of the human interferon-gamma molecule.

Biotechnology↗
PubMed2000

Measurement of furancarboxylic acid, a candidate for uremic toxin, in human serum, hair, and sweat, and analysis of pharmacological actions in vitro.

3-Carboxy-4-methyl-5-propyl-2-furanpropionic acid (CMPF), a candidate for uremic toxin, was measured in human hair for examining a possible utility as indicator of renal dysfunction. The serum concentration of CMPF was much higher (32.3 +/- 2.7 microg/ml, n = 17; mean +/- SEM) in uremic patients aged 40-55 years receiving hemodialysis treatment than in healthy younger subjects (3.61 +/- 0.19 microg/ml, n = 22), aged 18-23 years. However, the hair concentration of CMPF tended to be lower in the patients (6.8 +/- 1.7 ng/10 mg hair) than in the healthy younger subjects (15.8 +/- 4.5 ng/10 mg) and was significantly lower than that in the healthy age-matched subjects (22.4 +/- 5.3 ng/10 mg, n = 12), aged 40-47 years. Since CMPF was measurable in the sweat (4.4 +/- 3.7 ng/mg) collected from six out of seven healthy subjects examined, it was suggested that the contribution of sweat to the measurement of CMPF in hair was considerable. The fact that the uremic patients undergoing hemodialysis therapy had less sweat than healthy subjects may explain the lower concentration of CMPF in the patients' hair. The pathophysiological roles of CMPF in the body were attempted to be explored by using excised guinea pig organs, and human platelets and neutrophils. CMPF showed no remarkable effects in the concentration range of < or =10(-4) M except for only slight suppression of spontaneous contracture of guinea pig tenia coli at 10(-4) M. As far as the organs and tissues examined in the present study are concerned, the biological activity of CMPF itself, if any, may be very weak. Precaution should be taken against the delivery of a substance through sweat to hair when a small amount of substance is attempted to be measured in hair by employing a sensitive analytical method.

Adolescent↗
PubMed2000

Immunochemical detection of imidazolone in uremia and rheumatoid arthritis.

The advanced glycation end-product imidazolone is formed by reaction of arginine with 3-deoxyglucosone (3-DG), a reactive intermediate of the Maillard reaction, whose formation is non-oxidative. Using an antibody specific to this 3-DG-derived AGE, we demonstrated the presence of imidazolone-modified proteins in vivo in the urine and dialysate of patients with chronic renal failure, in the synovial fluid of patients with rheumatoid arthritis, as well as in vitro in human serum and human serum albumin incubated with glucose. Furthermore, we could show that in uremic patients the dimeric form of beta(2)-microglobulin is more susceptible to imidazolone modification than the monomeric one. Thus, the immunochemical detection of imidazolone may be a good marker for 3-DG-derived AGE modification in vivo and in vitro permitting a differentiation between the oxidative and the non-oxidative pathway of AGE generation.

Adult↗
PubMed2000

Preventive effect of vitamin E-containing liposome instillation on cataract progression in 12-month-old rats fed a 25% galactose diet.

The preventive effect of vitamin E (Vit. E)-containing liposome instillation on cataract progression was examined in 12-month-old Wistar rats fed a 25% galactose diet. Vit. E-containing liposomes prepared with dipalmitoylphosphatidylcholine and dioleoylphosphatidylcholine (7:3 w/w) were instilled into both eyes twice a day. Lenses of galactose-fed rats showed suture accentuation at 6 months of feeding and opacities in the cortex and nuclei at 8 months. Two months of Vit. E-containing liposome instillation, starting at 6 months of galactose feeding, retarded this cataract progression. Lenses of galactose-fed rats had increased Vit. E, lipid peroxide (LPO), galactitol, and water contents and decreased reduced glutathione (GSH) content at 6 months of feeding; increased LPO, galactitol, and water contents and decreased GSH content at 8 months. Sera of galactose-fed rats had increased Vit. E and cholesterol concentrations at 6 months of feeding. The liposome instillation increased lens Vit. E content with attenuation of the increased lens LPO content and the decreased lens GSH content but did not affect the changes in lens galactitol and water contents and serum Vit. E and cholesterol concentrations. These results indicate that instilled Vit. E-containing liposomes retard cataract progression in 12-month-old rats fed a 25% galactose diet, mainly by the antioxidative and membrane-stabilizing actions of Vit. E contained in the liposomes.

1,2-Dipalmitoylphosphatidylcholine↗
PubMed2000

An oral sorbent reduces overload of indoxyl sulphate and gene expression of TGF-beta1 in uraemic rat kidneys.

BACKGROUND: An oral adsorbent (AST-120) delays the progression of chronic renal failure (CRF). The aims of the present study are to determine the effects of AST-120 on the localization of indoxyl sulphate in uraemic rat kidneys, and to examine whether AST-120 reduces the renal cortical gene expression of transforming growth factor (TGF)-beta1, tissue inhibitor of metalloproteinase (TIMP)-1 and pro-alpha1(I)collagen, and ameliorates glomerular and tubulointerstitial injuries in uraemic rats. METHODS: Two weeks after 5/6-nephrectomy, 10 rats were divided into pairs such that both rats in each pair exhibited almost the same levels of serum creatinine, blood urea nitrogen and creatinine clearance. One rat from each pair was assigned to a control uraemic group, the other to a uraemic group which received AST-120 everyday for 11 weeks. The localization of indoxyl sulphate was studied by immunohistochemistry using a monoclonal anti-indoxyl sulphate antibody we had developed. The renal cortical gene expression was studied by using northern blotting. RESULTS: Rats treated with AST-120 showed decreased levels of serum creatinine, blood urea nitrogen and urinary protein as well as increased levels of creatinine clearance as compared with control uraemic rats. AST-120 markedly decreased indoxyl sulphate levels in both serum and urine. Immunohistochemistry demonstrated that indoxyl sulphate was localized in the renal proximal tubular epithelial cells, especially of dilated tubules, and that AST-120 markedly reduced the tubular staining of indoxyl sulphate. AST-120 attenuated interstitial fibrosis, tubular injury as well as glomerular sclerosis, and reduced the renal gene expression of TGF-beta1, TIMP-1 and pro-alpha1(I)collagen. CONCLUSIONS: AST-120 reduces the gene expression of TGF-beta1, TIMP-1 and pro-alpha1(I)collagen in the kidneys, and delays the progression of CRF, at least in part, by alleviating the overload of indoxyl sulphate on remnant proximal tubular epithelial cells.

Adsorption↗
PubMed2000

Safety assessment, in vitro and in vivo, and pharmacokinetics of emivirine, a potent and selective nonnucleoside reverse transcriptase inhibitor of human immunodeficiency virus type 1.

Emivirine (EMV), formerly known as MKC-442, is 6-benzyl-1-(ethoxymethyl)-5-isopropyl-uracil, a novel nonnucleoside reverse transcriptase inhibitor that displays potent and selective anti-human immunodeficiency virus type 1 (HIV-1) activity in vivo. EMV showed little or no toxicity towards human mitochondria or human bone marrow progenitor cells. Pharmacokinetics were linear for both rats and monkeys, and oral absorption was 68% in rats. Whole-body autoradiography showed widespread distribution in tissue 30 min after rats were given an oral dose of [(14)C]EMV at 10 mg/kg of body weight. In rats given an oral dose of 250 mg/kg, there were equal levels of EMV in the plasma and the brain. In vitro experiments using liver microsomes demonstrated that the metabolism of EMV by human microsomes is approximately a third of that encountered with rat and monkey microsomes. In 1-month, 3-month, and chronic toxicology experiments (6 months with rats and 1 year with cynomolgus monkeys), toxicity was limited to readily reversible effects on the kidney consisting of vacuolation of kidney tubular epithelial cells and mild increases in blood urea nitrogen. Liver weights increased at the higher doses in rats and monkeys and were attributed to the induction of drug-metabolizing enzymes. EMV tested negative for genotoxic activity, and except for decreased feed consumption at the high dose (160 mg/kg/day), with resultant decreases in maternal and fetal body weights, EMV produced no adverse effects in a complete range of reproductive toxicology experiments performed on rats and rabbits. These results support the clinical development of EMV as a treatment for HIV-1 infection in adult and pediatric patient populations.

Animals↗
PubMed2000

Inhibition of drug-metabolizing enzyme activity in human hepatic cytochrome P450s by bisphenol A.

Effect of bisphenol A on drug-metabolizing enzyme activities by human hepatic cytochrome P450s (CYP) was investigated. We measured aminopyrine N-demethylation by eleven kinds of cDNA-expressed CYPs. CYP2C19 and CYP2B6 catalyzed most efficiently the aminopyrine N-demethylation, followed by CYP2C8 and CYP2D6. Bisphenol A (1 mM) most efficiently inhibited aminopyrine N-demethylation by CYP2C8 and CYP2C19 by 82% and 85%, respectively, whereas inhibition of the activities by CYP 2B6 and 2D6 was less than 40%. Bisphenol A exhibited a noncompetitive-type inhibition of aminopyrine N-demethylase activity by CYP2C8 with Ki value of 97 microM. Additionally, we investigated the inhibitory effect of bisphenol A on CYP2C19-mediated S-mephenytoin 4-hydroxylation. Bisphenol A exhibited a mixed-type inhibition with Ki value of 113 microM. These results suggest that bisphenol A inhibits human hepatic CYP activities, especially CYP2C8 and CYP2C19.

Benzhydryl Compounds↗
PubMed2000

The value of plain radiographs in the prediction of outcome in pelvic fractures treated with embolisation therapy.

40 haemodynamically unstable patients with pelvic injuries were studied to assess the ability of plain radiographs to detect haemorrhagic sites. Pelvic radiographs and bilateral angiograms were reviewed separately for detection of haemorrhagic sites in both anterior and posterior segments. Sensitivity and specificity of pelvic radiographs for the detection of haemorrhagic sites were obtained by analysis of angiographic findings. Angiography demonstrated arterial injury in 106 divisions: 26 right anterior, 22 right posterior, 33 left anterior and 25 left posterior. Sensitivities of the radiographs for predicting haemorrhagic sites were higher in the anterior segment (right, 96%; left, 100%) than in the posterior segment (right, 73%; left, 83%). However, specificities were lower in the anterior segment (right, 79%; left, 78%) than in the posterior segment (right, 100%; left, 100%). In 15 (58%) of 26 patients with in-dwelling Foley catheters, including those with catheter deviation, the severity of anterior injury indicated on plain radiographs was correlated with angiographic findings. Plain radiographs of the pelvis proved useful for predicting haemorrhagic sites in haemodynamically unstable patients with pelvic fractures, especially in those with anterior fractures.

Adolescent↗
PubMed2000

Cis-N-(p-Coumaroyl)serotonin from Konnyaku, Amorphophallus konjac K. Koch.

Tobiko is produced as a by-product in the manufacture of konnyaku and comes to about 45% of dried konnyaku-imo. For a possible use of this powder, we studied its components. Serotonin, trans-N-(p-coumaroyl) serotonin, and a new compound, cis-N-(p-coumaroyl)serotonin, were characterized from this powder.

Magnoliopsida↗
PubMed2000

Synergism of protein kinase A, protein kinase C, and myosin light-chain kinase in the secretory cascade of the pancreatic beta-cell.

Protein phosphorylation by myosin light-chain kinase (MLCK), protein kinase A, and protein kinase C (PKC) plays a positive role in insulin secretion from the pancreatic beta-cell. To investigate the underlying mechanisms, we examined intracellular distribution of the insulin granules and MLCK by immunofluorescence and immunoelectron microscopies and also investigated intracellular traffic of the granules in cultured beta-cells (MIN6) by video microscopy. Considerable parts of MLCK immunoreactivity were colocalized with the insulin granules. Subcellular fractionation of MIN6 cell extracts revealed that myosin light chain (MLC) may be distributed with the insulin-rich fractions, and immunofluorescence staining using specific antibodies against mono- and diphosphorylated MLCs depicted presence of phosphorylated MLCs in the cytoplasm, in part, with colocalization with the insulin granules. Activation of PKC by 12-O-tetradecanoyl-phorbol 13-acetate (TPA) caused a shift of both insulin granules and MLCK to the cell periphery, which was not reproduced by the adenylate cyclase activator, forskolin. In contrast, forskolin, but not TPA, increased the granule movement. Costimulation of the beta-cell by TPA and forskolin induced drastic translocation of insulin granules and MLCK to the cell periphery, resulting in enormous potentiation of insulin release. These findings suggest that these protein kinases increase insulin granules in the ready-releasable pool by acting on different steps in the secretory cascade.

Cell Line↗
PubMed2000

[Factors influencing noncompliance with medication regimens in the elderly].

Poor medication compliance is a major issue in the health care of older patients. To identify risk factors for medication noncompliance in the elderly, inpatients aged 65 years and older at Nagoya University Hospital and at Chubu National Hospital underwent a comprehensive geriatric assessment and tests for the assessment of medication compliance. The dependency of medication assistance by a caregiver is associated with low physical function activity, cognitive impairment, depression and communication inability. Medication noncompliance was not associated with the score of any component of comprehensive geriatric assessment. There was a good relationship between patient's knowledge of medications and the frequency of dosage interval, both of which were associated with the score of instrumental ADL, cognitive function and communication ability. The knowledge was also associated with the medication compliance at Nagoya University Hospital but not at Chubu National Hospital. These results may suggest that the elderly patient's understanding of a medication regimen is important but that other factors are also required to maintain their treatment regimen.

Aged↗
PubMed2000

Selective uptake of dietary tocotrienols into rat skin.

Using a vitamin E mixture extracted from palm oil, the tissue distribution of dietary tocotrienols and tocopherols was examined in rats and mice. Wistar rats (4-wk-old) were fed a diet containing 48.8 mg/kg alpha-tocopherol, 45.8 mg/kg alpha-tocotrienol and 71.4 mg/kg gamma-tocotrienol for 8 wk. Nude mice (BALB/c Slc-nu, 8-wk-old) and hairless mice (SKH1, 8-wk-old) were fed the same diet for 4 wk. alpha-Tocopherol was abundantly retained in the skin, liver, kidney and plasma of rats and mice. alpha-Tocotrienol and gamma-tocotrienol were detected slightly in the liver, kidney and plasma, while substantial amounts of these tocotrienols were detected in the skin of both rats and mice. The present study suggests that the skin is a unique tissue in respect to its ability to discriminate between various vitamin E analogs.

Animals↗
PubMed2000

Increased glutathionyl hemoglobin in diabetes mellitus and hyperlipidemia demonstrated by liquid chromatography/electrospray ionization-mass spectrometry.

BACKGROUND: Erythrocytes contain a large amount of glutathione (GSH), which protects cells from oxidative injury. The purpose of this study was to examine whether hemoglobin (Hb) is modified with glutathione by oxidation of the thiol groups in diabetes mellitus and hyperlipidemia, and to determine the oxygen affinity of glutathionyl Hb. METHODS: Hb samples obtained from patients with type 2 diabetes, patients with hyperlipidemia, and healthy subjects were analyzed by liquid chromatography/electrospray ionization-mass spectrometry (LC/ESI-MS). Glutathionyl Hb was synthesized in vitro by incubating Hb with GSH. The oxygen affinity of glutathionyl Hb was determined by measuring its oxygen dissociation curve. RESULTS: We first demonstrated that the concentration of glutathionyl Hbbeta chains is markedly increased in the diabetic patients and hyperlipidemic patients compared with healthy subjects. The in vitro synthesis of glutathionyl Hb by incubation of Hb with GSH was enhanced by adding H(2)O(2), a reactive oxygen species, into the incubation solution. The glutathionyl Hb prepared in vitro by incubating Hb with GSH showed a marked increase in oxygen affinity and a marked decrease in the Hill coefficient compared with Hb incubated without GSH. CONCLUSIONS: Glutathionyl Hb may be useful as a clinical marker of oxidative stress. The increased concentrations of glutathionyl Hb with high oxygen affinity and low cooperativity in diabetes and hyperlipidemia may lead to reduced tissue oxygen delivery.

Chromatography, Liquid↗
PubMed2000

Stereoselective metabolism of cibenzoline, an antiarrhythmic drug, by human and rat liver microsomes: possible involvement of CYP2D and CYP3A.

Stereoselective metabolism of cibenzoline succinate, an oral antiarrhythmic drug, was investigated on hepatic microsomes from humans and rats and microsomes from cells expressing human cytochrome P450s (CYPs). Four main metabolites, M1 (p-hydroxycibenzoline), M2 (4,5-dehydrocibenzoline), and unknown metabolites M3 and M4, were formed by human and rat liver microsomes. The intrinsic clearance (CL(int)) of the M1 formation from R(+)-cibenzoline was 23-fold greater than that of S(-)-cibenzoline in human liver microsomes, whereas the R(+)/S(-)-enantiomer ratio of CL(int) for M2, M3, and M4 formation was 0.39 to 0.83. The total CL(int) for the formation of the four main metabolites from S(-)- and R(+)-cibenzoline was 1.47 and 1.64 microl/min/mg, respectively, suggesting that the total CL(int) in R(+)-enantiomer was slightly greater than that in S(-)-enantiomer in human liver microsomes. The M1 formation from R(+)-cibenzoline was highly correlated with bufuralol 1'-hydroxylation and CYP2D6 content and was inhibited by quinidine, a potent inhibitor of CYP2D6. Additionally, only microsomes containing recombinant CYP2D6 were capable of M1 formation. These results suggest that the M1 formation from R(+)-cibenzoline was catalyzed by CYP2D6. The formation of M2, M3, and M4 from S(-)- and R(+)-cibenzoline was highly correlated with testosterone 6beta-hydroxylation and CYP3A4 content. Ketoconazole, which is a potent inhibitor of CYP3A4/5, had a strong inhibitory effect on their formation, and the M4 formation from R(+)-cibenzoline was inhibited by quinidine by 45%. The formation of M2 was also inhibited by quinidine by 46 to 52% at lower cibenzoline enantiomers (5 microM), whereas the inhibition by quinidine was not observed at a higher substrate concentration (100 microM). In male rat liver microsomes, ketoconazole and quinidine inhibited the formation of the main metabolites, M1 and M3, >74% and 44 to 59%, respectively. These results provide evidence that CYP3A and CYP2D play a major role in the stereoselective metabolism of cibenzoline in humans and male rats.

Animals↗
PubMed1999

Inhibitory mechanism of sinapinic acid against peroxynitrite-mediated tyrosine nitration of protein in vitro.

The peroxynitrite-scavenging ability of some phenolic antioxidants, p-coumaric acid, caffeic acid and sinapinic acid, was examined and compared with ascorbic acid and tocopherol using 3-nitrotyrosine formation as a marker. Among these, caffeic acid and sinapinic acid strongly inhibited the formation of 3-nitrotyrosine in protein. The treatment of protein with peroxynitrite in the presence of sinapinic acid, but not caffeic acid, produced a novel product determined by reversed-phase high performance liquid chromatography (HPLC). The product formed was purified and then identified as a mono-lactone type dimer (ML) of sinapinic acid by nuclear magnetic resonance (NMR) and liquid chromatography-mass spectrometry (LC-MS). This ML was converted from a di-lactone type dimer, obtained from sinapinic acid with peroxidase/hydrogen peroxide, in neutral buffer. In this report, we have proposed that the ML of sinapinic acid is generated via one-electron oxidation by peroxynitrite treatment.

Chromatography, High Pressure Liquid↗
PubMed1999

3-Deoxyglucosone: metabolism, analysis, biological activity, and clinical implication.

3-Deoxyglucosone (3-DG) is synthesized via the Maillard reaction and the polyol pathway, and is detoxified to 3-deoxyfructose and 2-keto-3-deoxygluconic acid. 3-DG rapidly reacts with protein amino groups to form advanced glycation end products (AGEs) such as imidazolone, pyrraline, N'-(carboxymethyl)lysine and pentosidine, among which imidazolone is the AGE most specific for 3-DG. As demonstrated by using gas chromatography-mass spectrometry or high-performance liquid chromatography, plasma 3-DG levels are markedly increased in diabetes and uremia. Although the plasma 3-DG levels had been controversial, it was clearly demonstrated that its plasma level depends on the deproteinization method by which either free or total 3-DG, presumably bound to proteins, is measured. In diabetes, hyperglycemia enhances the synthesis of 3-DG via the Maillard reaction and the polyol pathway, and thereby leads to its high plasma and erythrocyte levels. In uremia, however, the decreased catabolism of 3-DG, which may be due to the loss of 3-DG reductase activity in the end-stage kidneys, may lead to high plasma 3-DG level. The elevated 3-DG levels in plasma and erythrocytes may promote the formation of AGEs such as imidazolone, as demonstrated by immunohistochemistry and immunochemistry using an anti-imidazolone antibody. Although AGE-modified proteins prepared in vitro exhibit a variety of biological activities, known AGE structures have not yet been demonstrated to show any biological activities. Because 3-DG is potent in the formation of AGEs and has some biological activities, such as cellular toxicity, it may be more important in the development of diabetic and uremic complications than the known AGE structures. By demonstrating that treatment with an aldose reductase inhibitor reduces the erythrocyte levels of 3-DG and AGEs, such as imidazolone, light is shed on the mystery of how aldose reductase inhibitors may prove beneficial in diabetic complications. These evidences suggest that 3-DG plays a principal role in the development of diabetic and uremic complications.

Aging↗
PubMed1999

Determination of glutathionyl hemoglobin in hemodialysis patients using electrospray ionization liquid chromatography-mass spectrometry.

We first detected glutathionyl hemoglobin (Hb) beta-chain in hemodialysis patients and healthy subjects using electrospray ionization liquid chromatography-mass spectrometry. The ratio of glutathionyl Hb beta-chain to total beta-chain was markedly increased in the hemodialysis patients as compared with healthy subjects. Glutathionyl Hb will be used as a new clinical marker of oxidative stress.

Adult↗