Search PubMed⌕ Search

Biomedical subjects

N Itoh

Publications and source records attributed to N Itoh.

At least 127 records · Page 7Linked to original sources
PubMed2000

Metallothionein acts as a cytoprotectant against doxorubicin toxicity.

The protective role of metallothionein (MT) against the myocardiotoxicity and hepatotoxicity of doxorubicin (Dox) was investigated in mice. Dox-induced elevations of plasma creatine kinase activity, a measure of myocardiac damage, and plasma glutamate pyruvate transaminase activity, reflecting hepatic damage, were prevented by pretreatment with an MT inducer. Pretreatment with zinc induced MT in the liver and heart, thereby reducing Dox toxicity in these two organs. Pretratment with n-hexane also induced MT and reduced Dox toxicity, but only in the liver. In primary hepatocyte cultures, the leakage of lactate dehydrogenase induced by Dox was prevented by zinc pretreatment. These results suggest that MT induction prevents Dox toxicity in vivo and in vitro. Furthermore, we determined that MT-null mice were more sensitive to the myocardiotoxic and hepatotoxic effects of Dox. These findings indicate that both basal and induced MT protect against Dox toxicity.

Alanine Transaminase↗
PubMed2000

[Antiviral effect of (S)-1-(3-hydroxy-2-phosphonylmethoxypropyl) cytosine on adenovirus].

PURPOSE: Adenovirus is the most frequent causative virus of conjunctivitis in Japan. Recently (S)-1-(3-hydroxy-2-phosphonylmethoxypropyl) cytosine (HPMPC) has been promoted as a new drug against adenoviral conjunctivitis. So we examined the antiviral activity of HPMPC against adenoviruses in vitro. METHOD: The antiviral activity of HPMPC against adenovirus (Ad) type 3, type 4, type 19, and type 37 isolated from conjunctivial scrapings in Japan and the prototype of adenovirus type 5 was examined by plaque reduction assay using A 549 cells in vitro. RESULTS: The 50% inhibitory dose (ID50) of HP-MPC was 3.50 (1.44-4.79) micrograms/ml for Ad type 3, 4.50 (4.17-4.92) micrograms/ml for Ad type 4, 2.11 (1.03-3.13) micrograms/ml for Ad type 5, 1.64 (1.40-2.02) micrograms/ml for Ad type 19, and 2.02 (1.17-2.73) micrograms/ml for type 37. The 50% cytotoxic dose of HPMPC for A 549 cells was 205 micrograms/ml by the deoxythimidine uptake inhibition test, and 537 micrograms/ml by the trypan blue exclusion inhibition test. CONCLUSIONS: HPMPC proved to be highly effective in inhibiting replication of adenoviruses at lower concentrations than the cytotoxic level in vitro.

Adenoviridae↗
PubMed2000

Genetic characterization of adenovirus strains isolated from patients with acute conjunctivitis in the city of São Paulo, Brazil.

Genome analysis was carried out on adenovirus strains isolated from patients with acute follicular conjunctivitis in the city of São Paulo, Brazil. Eighteen conjunctival scrapings, collected between December 1993 and March 1994, were analyzed by two methods: a combination of polymerase chain reaction with restriction fragment length polymorphism and viral DNA restriction analysis, carried out using 10 restriction endonucleases: BamHI, BglI, BglII, HindIII, KpnI, SacI, SalI, SmaI, XbaI, and XhoI. Among 11 adenovirus detected by cell culture isolation, nine were Ad8, and two were Ad7. By restriction analysis the Ad8 isolates were typed as two new variants-Ad8/D11 (seven of nine samples) and Ad8/D12 (two of nine samples). Ad7 isolates were identified as a subtype of the widespread genome type Ad7b and the virulent type Ad7h, a predominant genome type circulating in Argentina, Chile, and Uruguay but absent in Brazil until 1991.

Acute Disease↗
PubMed2000

[The effect of intraocular lidocaine in white rabbit eyes].

PURPOSE: Recently, intraocular lidocaine anesthesia has been used in cataract surgery. We studied the toxicity of intraocular unpreserved lidocaine for corneal endothelial cell and retina using Japanese white rabbits. METHOD: They were divided into two groups. One group was injected intracamerally and the other group was injected intravitreally with 0.2 ml of unpreserved lidocaine of 0%, 0.02%, 0.2%, or 2% concentration. The number of corneal endothelial cells was measured 1 week after the injection. The rabbits were killed after measurements, and their corneas were studied histologically. The retina was examined by electroretinogram from before the injection through 1 week after the injection. RESULTS: There was no significant change in number of corneal endothelial cells after injection of 0.2% lidocaine. However, histological abnormality was seen in corneal endothelial cells after 2% lidocaine injection. There was also significant change in electroretinogram with 2% lidocaine injection. No histological abnormality was seen in the retina 1 week after the injection. CONCLUSION: The rabbit cornea and retina manifested no serious changes after the injection of lidocaine at less than 0.2% concentration functionally and histologically.

Anesthesia, Local↗
PubMed2000

[Clinical evaluation of estramustine phosphate and vinblastine in patients with hormone-refractory prostate cancer].

We evaluated the efficacy of the combination of estramustine phosphate and vinblastine in 13 patients with hormone-refractory prostate cancer. Of 12 patients with an elevated prostate specific antigen (PSA) level at the start of treatment, 5 (42%) had a greater than 50% decrease in PSA level. In a patient with cervical and mediastinal lymph node metastases, about a 57% decrease was observed in bidimensional measurement. Side effects were mild and manageable. The survival rate was not significantly different between patients who showed a greater than 50% decrease in PSA levels or regression of lymph node metastases versus the other patients.

Aged↗
PubMed2000

[Small cell carcinoma of the urinary bladder: a case report].

A 64-year-old man presented with asymptomatic gross hematuria. Cystoscopy revealed a non-papillary broad-based tumor on the posterior wall of the bladder. He had no evidence of metastases. Urine cytology showed a cluster of molded tumor cells with naked hyperchromatic nuclei, which indicated small cell carcinoma. He received preoperative irradiation to the bladder and underwent partial cystectomy. Pathological examination of the specimen showed small cell carcinoma at the stage of pT2. Two years after the operation, he had no evidence of recurrence.

Carcinoma, Small Cell↗
PubMed2000

Clinical and analytical evaluation of an enzyme immunoassay for myelin basic protein in cerebrospinal fluid.

BACKGROUND: RIA of myelin basic protein (MBP) in cerebrospinal fluid (CSF) is commonly used as a biochemical marker of demyelination in patients with multiple sclerosis (MS). Our aim was to develop a sufficiently sensitive ELISA for MBP and evaluate it clinically in patients with MS. METHODS: The ELISA used anti-bovine MBP antibody coated on plates and biotinylated anti-MBP antibody. The bound antibody complex was quantified with streptavidin-horseradish peroxidase. MBP was determined in CSF from 84 MS patients and 55 patients with other neurological diseases. RESULTS: The respective within- and between-assay CVs were 4.7% and 7.2% at 200 ng/L, and 6. 3% and 8.8% at 2000 ng/L. The detection limit was 30 ng/L. Most of the MS patients with acute exacerbations had markedly increased MBP in the CSF. Longitudinal studies of six MS patients with recurrent exacerbation confirmed this observation. MBP concentrations from 78 MS patients, as tested with our ELISA, correlated well with those obtained by RIA (r = 0.9; P: <0.01), but the detection limit of the ELISA was much lower than that of the RIA. CONCLUSIONS: This convenient ELISA with higher sensitivity than the existing assays is a suitable routine assay that provides a diagnostic indicator of myelin breakdown in the central nervous system; moreover, it is an excellent indicator of MS disease activity.

Adolescent↗
PubMed2000

[Bacterial infection in the conjunctiva of patients with adenoviral conjunctivitis].

PURPOSE: We evaluate the microbiological features of mixed infection in adenovirus-infected conjunctiva. SUBJECTS: Isolation of bacteria was performed in 82 samples of adenoviral conjunctivitis at six eye clinics in Japan. METHODS: For microbiological diagnosis, we performed immunochromatography (IC) and polymerase chain reaction--restriction fragment length polymorphism (PCR-RFLP) analysis for detection and serotyping of adenovirus, and PCR for detection of herpes simplex virus (HSV) and Chlamydia trachomatis antigens out of 82 samples with adenoviral conjunctivitis. RESULTS: Pathogenic bacteria were isolated in 6 samples out of 82. Out of these 6 cases, 5 samples were gram-negative rods and most of them were Flavobacterium meningosepticum (4 samples). Adenovirus type 8 was isolated from all these mixed infection cases. However, HSV-1 and Chlamydia trachomatis were not found. CONCLUSIONS: From these results, it is suggested that gram-negative rods, especially F. meningosepticum, are the most common bacteria causing mixed bacterial infection in adenoviral conjunctivitis.

Adenovirus Infections, Human↗
PubMed2000

Distinct mechanisms of transport of ascorbic acid and dehydroascorbic acid in intestinal epithelial cells (IEC-6).

Ascorbic acid (AsA) is an essential nutrient for humans as they lack its biosynthesizing key enzyme. Its absorption mechanism in small intestinal epithelial cells still remains to be resolved. In this study, the transport mechanisms functioning on the uptake of AsA and its oxidized form, dehydroascorbic acid (DHA), were investigated using rat small intestinal epithelial cell line IEC-6. Both AsA and DHA were accumulated in the cells in time- and concentration-dependent manners, but their absorption kinetics were apparently different. The saturability of AsA uptake was shown at a considerably lower concentration in IEC-6 cells as well as other mammalian cells, indicating that this absorption was mediated by a specific transporting carrier. The absorption efficiency of AsA was about 1/5-1/10 that of DHA at the same concentration range and, moreover, the uptake of DHA was almost comparable to that of 2-deoxy-D-glucose, an alternative of glucose. The uptake of AsA was diminished by the removal of sodium ion, but not by the addition of glucose, whereas that of DHA was sodium ion-independent and effectively inhibited by glucose. In addition, phlorizin and cytochalasin B, which are blockers of glucose transporters, interfered the uptake of DHA more efficiently than that of AsA. These results indicate that there are at least two distinct transport systems of vitamin C in rat small intestinal epithelial cells; AsA is transported by a specific transporter and DHA is mainly transported by glucose transporter(s).

Animals↗
PubMed1999

Cerebroprotective properties of SM-20220, a potent Na(+)/H(+) exchange inhibitor, in transient cerebral ischemia in rats.

The aim of this study was to investigate the contribution of the Na(+)/H(+) exchanger to cerebral ischemia using SM-20220 (N-(aminoiminomethyl)-1-methyl-1H-indole-2-carboxamide methanesulfonate), a newly synthesized compound. In in vitro experiments, we evaluated the inhibitory effect of SM-20220 on the Na(+)/H(+) exchanger in cultured neurons and glial cells. The IC(50) of SM-20220 in neurons and glial cells was 5 nM and 20 nM, respectively. To examine the in vivo effects of SM-20220 on brain injury, we used a transient middle cerebral artery occlusion model in rats. SM-20220 given intravenously 1 h after occlusion significantly reduced the extent of cerebral edema, Na(+) content and infarcted area in a dose-dependent manner. The results of the present study suggest that the Na(+)/H(+) exchanger is involved in the aggravation of brain edema and infarction, and its inhibitor may exert protective effects on post-ischemic brain damage.

Amides↗
PubMed1999

Purification and characterization of a novel enzyme, L-threo-3-hydroxyaspartate dehydratase, from Pseudomonas sp. T62.

L-threo-3-Hydroxyaspartate dehydratase (L-threo-3-hydroxyaspartate hydro-lyase), which exhibited specificity for L-threo-3-hydroxyaspartate (K(m)=0.74 mM, V(max)=37.5 micromol min(-1) (mg protein)(-1)) but not for D-threo or D, L-erythro-3-hydroxyaspartate, was purified from a cell-free extract of Pseudomonas sp. T62. The activity of the enzyme was inhibited by hydroxylamine and EDTA, which suggests that pyridoxal 5'-phosphate and divalent cations participate in the enzyme reaction. The NH(2)-terminal amino acid sequence showed significant similarity to the Saccharomyces cerevisiae YKL218c gene product, a hypothetical threonine dehydratase. However, the purified enzyme showed no threonine dehydratase activity.

Amino Acid Sequence↗
PubMed1999

Cdc42 and Rac1 regulate the interaction of IQGAP1 with beta-catenin.

IQGAP1, a target of Cdc42 and Rac1 small GTPases, directly interacts with beta-catenin and negatively regulates E-cadherin-mediated cell-cell adhesion by dissociating alpha-catenin from the cadherin-catenin complex in vivo (Kuroda, S., Fukata, M., Nakagawa, M., Fujii, K., Nakamura, T., Ookubo, T., Izawa, I., Nagase, T., Nomura, N., Tani, H., Shoji, I., Matsuura, Y., Yonehara, S., and Kaibuchi, K. (1998) Science 281, 832-835). Here we investigated how Cdc42 and Rac1 regulate the IQGAP1 function. IQGAP1 interacted with the amino-terminal region (amino acids 1-183) of beta-catenin, which contains the alpha-catenin-binding domain. IQGAP1 dissociated alpha-catenin from the beta-catenin-alpha-catenin complex in a dose-dependent manner in vitro. Guanosine 5'-(3-O-thio)triphosphate (GTPgammaS).glutathione S-transferase (GST)-Cdc42 and GTPgammaS. GST-Rac1 inhibited the binding of IQGAP1 to beta-catenin in a dose-dependent manner in vitro, whereas neither GDP.GST-Cdc42, GDP. GST-Rac1, nor GTPgammaS.GST-RhoA did. The coexpression of dominant active Cdc42 with IQGAP1 suppressed the dissociation of alpha-catenin from the cadherin-catenin complex induced by the overexpression of IQGAP1 in L cells expressing E-cadherin (EL cells). Consistent with this, the overexpression of either dominant negative Cdc42 or Rac1 resulted in the reduction of E-cadherin-mediated cell adhesive activity in EL cells. These results indicate that Cdc42 and Rac1 negatively regulate the IQGAP1 function by inhibiting the interaction of IQGAP1 with beta-catenin, leading to stabilization of the cadherin-catenin complex.

Carrier Proteins↗
PubMed1999

A novel strategy for identifying differential gene expression: An improved method of differential display analysis.

We propose a novel alternative approach, an advanced method for recently developed strategies, for identifying differentially expressed genes. Firstly, double-stranded cDNAs were digested using Sau3AI and the 3'-end restriction fragments of the cDNA were ligated to a double-stranded adapter. Next, the restriction fragments were directly amplified using several combinations of adapter-specific primers and FITC-labeled oligo dT primers. The selected cDNA fragments were displayed on a polyacrylamide gel. Neither nested PCR nor purification of 3'-end fragments are necessary. We examined the validity of this approach by evaluating gene expression changes during granulocytic differentiation of HL-60 cells. This method can theoretically detect almost all gene expression changes more rapidly and through simpler manipulations than by any other approach.

Cell Differentiation↗
PubMed1999

Cutting edge: homologous recombination of the MHC class I K region defines new MHC-linked diabetogenic susceptibility gene(s) in nonobese diabetic mice.

To localize the MHC-linked diabetogenic genes in the nonobese diabetic (NOD) mouse, a recombinational hotspot from the B10.A(R209) mouse was introduced to the region between the MHC class I K and class II A of the NOD mouse with the recombinational site centromeric to the Lmp2/Tap1 complex by breeding the two strains. Replacement of the NOD region centromeric to the recombinational site with the same region in R209 mice prevented the development of diabetes (from 71 to 3%) and insulitis (from 61 to 15%) in the N7 intra-MHC recombinant NOD mice. Similarly, the replacement of the NOD class II A, E and class I D region with the same region in R209 mice prevented the diseases (diabetes, from 71 to 0%; insulitis, from 61 to 3%). In addition to the MHC class II genes, there are at least two MHC-linked diabetogenic genes in the region centromeric to Lmp2.

Animals↗
PubMed1999

Signaling through fibroblast growth factor receptor 2b plays a key role in the development of the exocrine pancreas.

The development of the pancreas depends on epithelial-mesenchymal interactions. Fibroblast growth factors (FGFs) and their receptors (FGFRs 1-4) have been identified as mediators of epithelial-mesenchymal interactions in different organs. We show here that FGFR-2 IIIb and its ligands FGF-1, FGF-7, and FGF-10 are expressed throughout pancreatic development. We also show that in mesenchyme-free cultures of embryonic pancreatic epithelium FGF-1, FGF-7, and FGF-10 stimulate the growth, morphogenesis, and cytodifferentiation of the exocrine cells of the pancreas. The role of FGFs signaling through FGFR-2 IIIb was further investigated by inhibiting FGFR-2 IIIb signaling in organocultures of pancreatic explants (epithelium + mesenchyme) by using either antisense FGFR-2 IIIb oligonucleotides or a soluble recombinant FGFR-2 IIIb protein. Abrogation of FGFR-2 IIIb signaling resulted in a considerable reduction in the size of the explants and in a 2-fold reduction of the development of the exocrine cells. These results demonstrate that FGFs signaling through FGFR-2 IIIb play an important role in the development of the exocrine pancreas.

Animals↗
PubMed1999

FGF-10 is a growth factor for preadipocytes in white adipose tissue.

FGF-10 is a mesenchymal factor affecting epithelial cells during pattern formation. However, the expression and physiological role of FGF-10 in adults remains to be elucidated. We examined the expression of FGF-10 mRNA in a variety of adult rat tissues, and found to be most abundant in white adipose tissue. In white adipose tissue, FGF-10 mRNA was expressed in preadipocytes but not in mature adipocytes. The expression in white adipose tissue during postnatal development was also examined. The expression level was low at postnatal day 10 (P10). However, FGF-10 mRNA was abundantly detected later on (P28 and P48) when white adipose tissue growth was stimulated. We also examined the activity of recombinant FGF-10 for primary rat preadipocytes. FGF-10 showed significant mitogenic activity for primary preadipocytes, but did not affect the differentiation of preadipocytes. The expression profile of FGF-10 mRNA and the activity of FGF-10 reported here indicate that FGF-10, a unique secreted factor produced in white adipose tissue, acts as a growth factor for preadipocytes in white adipose tissues.

Adipocytes↗
PubMed1999

Direct interaction of lignin and lignin peroxidase from Phanerochaete chrysosporium.

Binding properties of lignin peroxidase (LiP) from the basidiomycete Phanerochaete chrysosporium against a synthetic lignin (dehydrogenated polymerizate, DHP) were studied with a resonant mirror biosensor. Among several ligninolytic enzymes, only LiP specifically binds to DHP. Kinetic analysis revealed that the binding was reversible, and that the dissociation equilibrium constant was 330 microM. The LiP-DHP interaction was controlled by the ionization group with a pKa of 5.3, strongly suggesting that a specific amino acid residue plays a role in lignin binding. A one-electron transfer from DHP to oxidized intermediates LiP compounds I and II (LiPI and LiPII) was characterized by using a stopped-flow technique, showing that binding interactions of DHP with LiPI and LiPII led to saturation kinetics. The dissociation equilibrium constants for LiPI-DHP and LiPII-DHP interactions were calculated to be 350 and 250 microM, and the first-order rate constants for electron transfer from DHP to LiPI and to LiPII were calculated to be 46 and 16 s-1, respectively. These kinetic and spectral studies strongly suggest that LiP is capable of oxidizing lignin directly at the protein surface by a long-range electron transfer process. A close look at the crystal structure suggested that LiP possesses His-239 as a possible lignin-binding site on the surface, which is linked to Asp-238. This Asp residue is hydrogen-bonded to the proximal His-176. This His-Asp...proximal-His motif would be a possible electron transfer route to oxidize polymeric lignin.

Amino Acid Sequence↗