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Biomedical subjects

T Naito

Publications and source records attributed to T Naito.

At least 199 records · Page 11Linked to original sources
PubMed1993

Effects of prostaglandins on ornithine decarboxylase activity in rat small intestine.

Role of prostaglandins on feeding-associated induction of ornithine decarboxylase in small intestine was studied. Rats received intraperitoneal injection of either saline, or 16,16-dimethyl prostaglandin E2, or TRY-200 (a stable prostaglandin I2 analog), or refeeding, after a 44 hr-fast. Four hours later, mucosae from duodenum, jejunum, and ileum were scraped for subsequent measurements of enzyme activity of ornithine decarboxylase by a radiometric technique. Refeeding resulted in a profound induction of enzyme activity throughout the small intestine. Parenteral administration of prostaglandin I2 also led to a significant induction with the level similar to refeeding. The stimulatory effect of prostaglandin I2 was completely abolished by a specific and irreversible enzyme inhibitor, difluoromethylornithine. Prostaglandin E2 had a similar but lesser effect than prostaglandin I2 on the induction of the enzyme activity. Pretreatment with indomethacin, a cyclooxygenase inhibitor had no effect on feeding-associated enzyme induction. These results indicate that although exogenous prostaglandin I2 appears to be a potent stimulant for ornithine decarboxylase activity in rat small intestine, endogenous prostaglandins seem to play little or no role in feeding-associated induction of ornithine decarboxylase.

Analysis of Variance↗
PubMed1993

Presence of lactate dehydrogenase-containing vesicles in an intramembranous ossifying tissue: new-born mouse calvaria.

Lactate dehydrogenase-containing vesicles have been isolated from the extracellular matrix of the calvaria of new-born mice. The calvariae, intramembranous ossification tissue, were removed from 2-day-old mice, followed by the separation of the extracellular matrix vesicle fraction after collagenase digestion. Lactate dehydrogenase-containing vesicles with a density different from that of matrix vesicles were detected in the matrix vesicle fraction. Lactate dehydrogenase in these vesicles did not result from cell lysis and vesicle capture during the preparation of the matrix vesicle fraction. The isoenzyme pattern of lactate dehydrogenase in lactate dehydrogenase-containing vesicles was nearly identical to that of cytosolic lactate dehydrogenase of the cell fraction. Other cytosolic enzymes were not detected in lactate dehydrogenase-containing vesicles, suggesting the presence of a mechanism for specific uptake of cytosolic lactate dehydrogenase during the in vivo formation of the vesicles. This is the first report on the presence of lactate dehydrogenase-containing vesicles in the intramembranous ossification site.

Animals↗
PubMed1993

Metabolism and distribution in the rat of peak E substance, a constituent in L-tryptophan product implicated in eosinophilia-myalgia syndrome.

Peak E substance, 1,1'-ethylidenebis[tryptophan], a contaminant found in L-tryptophan tablets, has been suggested as a causative agent for eosinophilia-myalgia syndrome (EMS). Peak E substance (50 mg/kg) was administered perorally to Wistar rats to determine its metabolism and distribution. A purification procedure using Bond Elut C8 cartridges followed by HPLC was developed for the determination of peak E substance. The plasma concentration of peak E substance was 136 ng/ml at 1 h, and urinary excretion was 717 ng at 5 h and 10342 ng for 5-24 h, showing slow excretion of peak E substance into urine. The amount of peak E substance in the contents of the large intestine at 5 h, however, was 3136 micrograms, much greater than urinary excretion for 24 h, indicating considerable transfer of peak E substance to large intestine without decomposition by gastric fluid in the stomach. We have detected for the first time not only the occurrence of peak E substance in plasma and urine, but also 1-methyl-tetrahydro-beta-carboline-3-carboxylic acid (MTCA) in blood and organs of rats treated with peak E substance, thereby suggesting MTCA as one of the the metabolites of peak E substance. The amount of MTCA in the contents of the large intestine as well as in urine of rats treated with peak E substance was significantly greater than in L-tryptophan-treated rats (50 mg/kg p.o.), demonstrating that MTCA was more readily produced from peak E substance than from L-tryptophan. Finally, we propose acetaldehyde-induced production of MTCA from peak E substance.

Animals↗
PubMed1993

Microsurgical reconstruction in limb-salvage procedures: comparison between primary and secondary reconstruction.

Limb-salvaging procedures after malignant tumor resection in the extremities were performed in 22 cases, utilizing microsurgical tissue transplantation. Five patients had soft-tissue tumors and 17 had bone tumors. Thirteen cases were primarily and nine were secondarily reconstructed. The advantages and disadvantages of both primary and secondary reconstructions were compared: as to technical difficulty, primary reconstruction was much easier. Chemotherapy was necessary just before and/or after reconstruction in eight of 13 cases of primary reconstruction. Delayed union or non-union occurred more frequently in patients who required chemotherapy, but eventual union was achieved in all cases by adding a conventional bone graft. As for oncologic and functional status, there was no difference in oncological status between the primary and secondary groups, but the primary reconstructions showed better functional results. Although individualized treatment is of utmost importance when utilizing microsurgical reconstruction to save limbs, primary reconstruction can be done most successfully when there is a wide surgical margin after tumor resection and when attention is paid to the avoidance of such complications as delayed union or non-union.

Adolescent↗
PubMed1993

Successful treatment of a patient with idiopathic factor VIII inhibitor with double filtration plasmapheresis and steroid administration.

We report a 74-year-old Japanese woman who had bleeding due to a factor VIII inhibitor in the absence of diseases known to be associated with its development. She abruptly developed a large painful purpura extending from the right hip to the thigh followed by an intramuscular haematoma of her left anterior chest. Examinations revealed a marked depression of factor VIII activity (5%) and the presence of 31 Bethesda units/ml factor VIII inhibiting activity. The phenotypes of these inhibitors were of the IgG-kappa and IgG-lambda types. She was treated with oral prednisolone and double filtration plasmapheresis (DFPP). The inhibitors rapidly disappeared after three sessions of plasmapheresis and her plasma factor VIII activity increased to a normal level. During this treatment, no major adverse effects such as thrombosis and infection were observed and transfusion of fresh frozen plasma (FFP) was not necessary. Heterogeneity of idiopathic factor VIII inhibitors in elderly patients is common and spontaneous disappearance or elimination of such inhibitors by treatment is often difficult to achieve. However, the combination of oral prednisolone and double filtration plasmapheresis is effective and safe for idiopathic factor VIII inhibitors and is a worthwhile approach to treatment.

Aged↗
PubMed1993

Modulation of ethanol-mediated CYP2E1 induction by clofibrate and L-carnitine in rat liver.

To understand the effects of lipid-lowering agents on the ethanol-induction of hepatic CYP2E1, clofibrate and L-carnitine were administered to adult male rats. The administration of ethanol in the diet (containing 21% calories as ethanol, given for 3 weeks) increased levels of hepatic CYP2E1 protein (1.9-fold that of untreated controls) and mRNA (2.1-fold). In contrast, the administration of clofibrate (0.1%v/v) in an ethanol-containing diet did not significantly increase either CYP2E1 protein (1.1-fold) or mRNA (0.8-fold), in spite of the significant increases in blood ketone bodies. Administration of L-carnitine alone had no clear effect on CYP2E1 and blood ketone body levels. Co-administration of L-carnitine, however, increased liver microsomal CYP2E1 protein (2.5-fold) in rats given an ethanol-containing diet. No difference was observed in the mRNA levels in rats receiving ethanol with and without L-carnitine. These results indicate that clofibrate and L-carnitine modulate ethanol-mediated induction of hepatic CYP2E1 independent of blood levels of ketone bodies. It is also suggested that these lipid-lowering agents affected hepatic CYP2E1 through particular mechanisms, suppression of the specific mRNA and post-translation stabilization.

Animals↗
PubMed1993

The effect of serum on low density lipoprotein metabolism of human monocyte-derived macrophages.

Macrophages oxidatively modify low density lipoprotein (LDL). These cells then recognize and take up oxidized LDL (OxLDL) via the scavenger receptor. In the present study, we examined the effect of lipoprotein depleted serum (LPDS) on the oxidative modification of LDL and its uptake and degradation by human monocyte-derived macrophages. LPDS inhibited LDL oxidation in a concentration-dependent manner and the complete inhibition was observed in the concentration from 2.5 to 10.0%. In the presence of 5% of LPDS, cell-associated 125I-LDL was reduced by 70%, compared with that in the absence of LPDS. In contrast, 125I-LDL degradation increased in the presence of LPDS. The ratio of degradation products to cell-associated radioactivity in the presence of LPDS was five-fold greater than that in the absence of LPDS. In the presence of LPDS, unlabeled LDL competed for about 50% of cellular uptake and degradation of 125I-LDL. In the absence of LPDS, however, unlabeled LDL competed for only 20% of uptake and only 30% of degradation of 125I-LDL. Unlabeled OxLDL competed for about 80% of uptake and degradation in the absence of LPDS. These results suggest that LPDS inhibited the production of OxLDL which was taken up by macrophages via the pathway for the OxLDL.

Blood Physiological Phenomena↗
PubMed1992

T lymphocytes increase the synthesis of esterified cholesterol in human monocyte-derived macrophages by activation of the scavenger pathway.

Immunohistochemical analyses have shown the presence of T lymphocytes (T-cells) in atherosclerotic places in addition to macrophages and smooth muscle cells. To elucidate the role of T-cells in the formation of atherosclerotic lesions, we studied whether T-cells can stimulate the scavenger pathway and promote esterified cholesterol (EC) synthesis by [14C]oleate incorporation in macrophages. Macrophages and T-cells were co-cultured in two ways. In one culture, macrophages were in direct contact with T-cells (direct contact form). In the other, macrophages and T-cells were separated by Transwell membrane, but shared the same culture medium via the membrane (indirect contact form). Based on the incorporation of [14C]oleate into EC, macrophages strikingly increased EC synthesis in both forms of co-culture. This increase was proportional to the number of T-cells present and was inhibited by cyclosporin A. When macrophages were co-cultured indirectly in contact with T-cells in the presence of AcLDL for 24 h, and the T-cells were subsequently removed, EC synthesis in macrophages increased. However, this increase was not observed in macrophages that were rinsed twice with PBS. When macrophages, previously incubated with AcLDL for 24 h, were co-cultured indirectly in contact with T-cells for 24 h, the medium were prepared as activated T-cell-conditioned medium (aTCM). EC synthesis in macrophages cultured with aTCM increased. The ability of aTCM to increase EC synthesis disappeared upon repeated freezing/thawing, boiling and trypsin treatment. T-cells (indirect contact form) and aTCM similarly increased AcLDL-binding and -degradation in macrophages. These results indicated that T-cells secreted an active substance(s), protein in nature, which could activate the scavenger pathway and increase EC synthesis in macrophages. These observations suggest that T-cells can promote the uptake of modified lipoproteins by macrophages to induce foam cell-formation.

Arteriosclerosis↗
PubMed1992

The protease from Vibrio cholerae nicks arginine at position 192 from the N-terminus of the heat-labile enterotoxin a subunit from enterotoxigenic Escherichia coli.

It was examined where a protease purified from Vibrio cholerae might nick the heat-labile enterotoxin (LT) A subunit from enterotoxigenic Escherichia coli. LT was digested by the protease and contained a fragment which had the same mobility on SDS-PAGE as that of the A1 fragment of LT digested by trypsin. The biological activity of LT by this protease was also identical to that of LT by trypsin. The amino acid sequence of the N-terminus of the A2-like fragment was Thr-Ser-Thr-Gly, which corresponded to the sequence from 193 to 196 of the A subunit. These data suggest that this protease, like trypsin, nicks arginine at position 192 from the N-terminus of the A subunit and that the biological activation of LT by this protease is similar to that by trypsin.

Amino Acid Sequence↗
PubMed1992

Up-regulated MHC-class II expression and gamma-IFN and soluble IL-2R in lupus nephritis.

Expression of MHC-class II molecules (HLA-DR and -DQ), serum gamma-interferon (gamma-IFN) and soluble interleukin-2 receptor (sIL-2R) levels were studied in 35 Japanese patients with lupus nephritis (LN) to clarify intraglomerular cellular activation and cytokine involvement in human LN. In 11 normal kidney specimens, HLA-DR(Ia1) was noted in glomerular tufts, but HLA-DQ was either not or was faintly detected in glomeruli by the indirect immunofluorescence technique. HLA-DR and -DQ were observed mainly on the surface of glomerular endothelial cells in 100% and 50% of 28 lupus kidney specimens except for necrotic or sclerotic lesions. HLA-DQ was expressed in a high incidence of 67%, 86% in patients with proliferative LN (WHO Class III-IV) and active lesions, respectively. Serum gamma-IFN and sIL-2R levels were 1.2 +/- 0.2 U/ml and 190 +/- 24 U/ml (mean +/- SEM; N = 30) in normal controls, and elevated in patients with proliferative LN (4.1 +/- 1.0 U/ml, 383 +/- 81 U/ml, N = 25), especially with active lesions (6.2 +/- 1.5 U/ml, 500 +/- 110 U/ml, N = 14). Overall, glomerular lesions such as HLA-DQ expression, the activity index and leukocyte infiltration correlated positively with serum gamma-IFN levels (r = 0.55; P less than 0.01 for HLA-DQ, r = 0.68; P less than 0.001 for activity index, r = 0.38; P less than 0.05 for leukocyte infiltration), but not with serum sIL-2R levels, anti-DNA antibody titers and CH50 titers.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1992

Detection and quantitative assessment of a Vibrio cholerae O1 species in several foods by a novel enzyme immunoassay.

A selected antibody enzyme immunoassay (SAEIA) for the general detection of Vibrio cholerae O1 species has been developed using the immunological reagents of a rabbit antiserum specific for V. cholerae O1 classical Inaba 569B and immobilized cell fragments of V. cholerae O1 El Tor 85P6, and beta-D-galactosidase-labeled goat anti-rabbit immunoglobulin G as tracer. The SAEIA was specific for V. cholerae O1 species and showed low cross-reaction values to other microorganism species tested including Vibrio parahaemolyticus. The detection limit of the SAEIA was 4,500 cells per assay for all the 13 strains of V. cholerae O1 examined. Quantitative comparison on the growth of the El Tor 85P4 in several foods cultured for 24 hr were studied using the SAEIA. Preceding the experiments, little inhibition of every food homogenate for the measurement of the SAEIA was first demonstrated and then the homogenate was directly used for an assay sample. The interaction of the growth of Escherichia coli to that of V. cholerae O1 in a food was also found to be little under the mixed culturing of both bacteria using the SAEIA.

Escherichia coli↗
PubMed1992

Studies on novel pili from Shigella flexneri. I. Detection of pili and hemagglutination activity.

Pili were detected using electron microscopy in clinical isolates of Shigella flexneri which had been continuously subcultivated in liquid media. Morphologically, the pili appeared as thin, flexible, cylindrical structures of up to 2-5 microns in length and about 3-5 nm in diameter. Two strains showed mannose-resistant (MR) hemagglutination to fresh fowl erythrocytes (type 4), and one to tannic acid-treated horse erythrocyte (type 3) pili. These pili are novel and different from the mannose-sensitive (MS) type 1 pili described by Duguid and Gillies.

Animals↗
PubMed1992

Role of plasminogen activator inhibitor on nephrotoxic nephritis and its modulation by tumor necrosis factor.

To evaluate the suggested imbalance between coagulation and fibrinolysis in the development of glomerulonephritis, plasminogen activator inhibitor (PAI) activity was studied in the plasma of rats with nephrotoxic nephritis. PAI activity rose within 1 h of the injection of nephrotoxic globulin (NTG), peaked at 2 h and returned to the normal range within 24 h. PAI activity was dependent on the dose of NTG and increased significantly during passage through the kidney. PAI activity was also detected in the culture supernatant from isolated glomeruli with nephrotoxic nephritis. Intracapillary fibrin deposits were formed within 2 h; their numbers increased gradually over 24 h. Tumor necrosis factor (TNF) also induced a progressive increase in PAI activity in normal rats. The injection of TNF to rats with NTG synergistically accelerated both the increase in PAI activity and the prevalence of fibrin deposits. These results suggest that PAI may be released from the glomeruli affected by nephrotoxic nephritis and imply that PAI may play a role in the local coagulation in the capillaries of the nephritic kidneys, although this is probably not the only mechanism which explains the continued formation of the glomerular fibrin deposits.

Animals↗
PubMed1992

Preparation and antitumor activity of 2''-O-, 3''-O- and 2'',3''-di-O-substituted derivatives of etoposide.

The 2''-O-, 3''-O- and 2'',3''-di-O-substituted derivatives (4a--p) of etoposide were prepared by nucleophilic substitution of 4'-O-benzyloxycarbonyletoposide (2) followed by deprotection. Controlled reaction (a limited amount of reagents and low temperature) was required for preparing the mono-O-substituted derivatives. In terms of ED125 values, doses which show 125% of T/C against P388 leukemia in mice, both the 2''-O-acetate (4a, ED125 = 0.18 mg/kg) and 3''-O-acetate (4b, 0.23 mg/kg) were nearly as active as etoposide (1, 0.19 mg/kg), while the 2'',3''-di-O-acetate (4c, 1.9 mg/kg) was somewhat less potent. In the replacement with other substituents, antitumor activity of the 2''-O-substituted derivatives was affected much more by the difference of the substituents as compared with that of the corresponding 3''-O-substituted derivatives. In the 2'',3''-di-O-substituted derivatives, the activity was decreased additively on the substituents.

Animals↗
PubMed1992

Noonan syndrome presenting growth hormone neurosecretory dysfunction.

Noonan syndrome has been diagnosed by the characteristic physical stigmata for more than two decades. Recent studies of growth hormone secretory pattern provide a new category of growth hormone neurosecretory dysfunction to characterize short stature. We describe herein a case of growth hormone neurosecretory dysfunction in a 16-year-old boy with Noonan syndrome. Growth hormone neurosecretory dysfunction was diagnosed primarily based on the low amplitude and small numbers of the spontaneous bursts of growth hormone secretion during 12-hour nocturnal growth hormone sampling. Treatment with synthetic human growth hormone has markedly accelerated the growth velocity for one year and a half. This case notes the wide spectrum of short stature in Noonan syndrome and the effectiveness of treatment with human growth hormone.

Adolescent↗