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Biomedical subjects

M Ishii

Publications and source records attributed to M Ishii.

At least 91 records · Page 5Linked to original sources
PubMed2001

Detection of dichromate (VI)-induced DNA strand breaks and formation of paramagnetic chromium in multiple mouse organs.

DNA single-strand breaks (and/or alkali-labile sites) induced by Cr(VI) were evaluated with the alkaline single cell gel electrophoresis (SCG) (Comet) assay in five organs (liver, kidney, spleen, lung, and brain) of male mice dosed with K(2)Cr(2)O(7) (20 mg Cr/kg) by a single ip injection in vivo, and the formation of paramagnetic Cr(V) in these organs was investigated by electron spin resonance (ESR) spectrometry. Furthermore, the in vivo effects of deferoxamine (DFO), an iron chelator, and dimethylthiourea (DMTU), a hydroxyl radical scavenger, on the formation of Cr(V) and DNA strand breaks induced by the metal in the liver and kidney were examined. SCG assay detected DNA strand breaks were detected in the liver and kidney at 15 min and showed that they were being repaired at 3 h after Cr(VI) injection. The ESR spectra of paramagnetic Cr(V) were also observed in the liver and kidney for 15 min to 24 h after Cr(VI) injection. In contrast, there were no significant levels of DNA strand breaks and Cr(V) in the spleen, lung, or brain. The pretreatment of mice with DFO reduced the formation of Cr(VI)-induced DNA strand breaks and Cr(V) complexes as well as the total contents of Cr in the liver and kidney at 15 min after the metal injection. In the case of the pretreatment with DMTU, DNA strand breaks induced by Cr(VI) were suppressed in the liver and kidney at 15 min, without any influence on the levels of Cr(V) complexes and total Cr contents in the organs. The in vitro study showed that DFO decreased the levels of Cr(V)-GSH complexes and Cr(V)-mediated hydroxyl radicals, while DMTU reduced only the levels of Cr(V)-mediated hydroxyl radicals without affecting the formation of Cr(V)-GSH complexes. These results demonstrated that the SCG assay may be useful for detecting DNA strand breaks and/or alkali-labile sites caused by Cr(VI) in vivo. The results also indicated that the in vivo formation of hydroxyl radicals during the reduction of Cr(VI) may play an important role in the induction of the DNA strand breaks caused by this metal and implied that the levels of Cr(V) inside the cells may not always be related to the induction of DNA strand breaks.

Animals↗
PubMed2001

Torn-off balloon tip of Z-5 atrial septostomy catheter.

Creation of atrial communication was performed in a newborn with critical aortic stenosis. After the success of the initial creation, balloon atrial septostomy using Z-5 catheter was performed. When catheter was pulled back, the tip of the balloon was torn off. This experience could be considered as noteworthy when using this catheter in patients with unusually thick atrial septum.

Angioplasty, Balloon, Coronary↗
PubMed2001

Osteoprotegerin inhibits in vitro mouse osteoclast formation induced by joint fluid from failed total hip arthroplasty.

Osteoprotegerin (OPG) is a key regulator of osteoclastogenesis. We investigated the presence of OPG and bone-resorbing cytokines, the potential of osteoclastic differentiation in joint fluid from failed total hip arthroplasty (THA), and the inhibitory effect of OPG on osteoclast formation in vitro induced by the joint fluid. The study was aimed to clarify one important step in the cascade of periprosthetic osteolysis in the process of implant loosening. OPG levels in failed THA joint fluid of 20 cases were significantly lower than osteoarthritis (OA) joint fluid of 15 cases (p < 0.001). The levels of bone-resorbing cytokines, interleukin (IL)-1beta, and IL-6 were significantly higher in failed THA joint fluid than OA fluid (p < 0.001 and p = 0.001, respectively). Marked osteoclast formation was observed in the presence of failed THA joint fluid in the mouse coculture system, when compared to OA fluid (p < 0.001). The addition of 100 ng/mL OPG to the mouse coculture system completely inhibited osteoclast formation in the presence of failed THA joint fluid (p < 0.001). The data suggest that low levels of OPG combined with higher IL-1beta and IL-6 levels represent the potential of osteoclast differentiation and its activation in failed THA joint fluid. Inhibition of osteoclastogenesis in vitro by OPG suggests that a low level of OPG with elevated bone resorbing cytokines contributes to periprosthetic osteolysis via osteolytic joint fluid, thus leading to THA prosthesis loosening.

Animals↗
PubMed2001

Nitrate respiratory metabolism in an obligately autotrophic hydrogen-oxidizing bacterium, Hydrogenobacter thermophilus TK-6.

Hydrogenobacter thermophilus strain TK-6 was observed to grow anaerobically on nitrate as an electron acceptor when molecular hydrogen was used as an energy source. Nitrite was detected as the product of a respiratory reaction. 15NO, 15N2O, and 15N2 were detected with Na15NO3 as an electron acceptor. Western immunoblot analysis showed that cell-free extracts from cells grown on nitrate reacted with antibodies against heme cd1-type nitrite reductase from Pseudomonas aeruginosa. The positive bands, which had molecular masses similar to that of the heme cd1-type nitrite reductase, were also stained by heme staining. These results indicate that nitrite reductase of strain TK-6 is a heme cd1-type enzyme. Activity of ATP:citrate lyase, one of the key enzymes of the reductive TCA cycle, was detected in cell-free extract of cells cultivated on nitrate, which indicates that the cycle operates during anaerobic growth.

Adenosine Triphosphate↗
PubMed2001

Changes in product formation and bacterial community by dilution rate on carbohydrate fermentation by methanogenic microflora in continuous flow stirred tank reactor.

Changes in product formation during carbohydrate fermentation by anaerobic microflora in a continuous flow stirred tank reactor were investigated with respect to the dilution rate in the reactor. In the fermentation by methanogenic microflora, stable methane fermentation, producing methane and carbon dioxide, was observed at relatively low dilution rates (less than 0.33 d(-1) on glucose and 0.20 d(-1) on cellulose). Decomposition of cellulose in the medium was a rate-limiting step in the reaction, because glucose was easily consumed at all applied dilution rates (0.07-4.81 d(-1)). Intermediate metabolites of methane fermentation, such as lactate, ethanol, acetate, butyrate, formate, hydrogen, and carbon dioxide, were accumulated as dilution rate increased. Maximum yield of hydrogen was obtained at 4.81 d(-1) of dilution rate (0.1 mol/mol glucose on glucose or 0.7 mol/mol hexose on cellulose). Lactate was the major product on glucose (1.2 mol/mol glucose), whereas ethanol was predominant on cellulose (0.7 mol/mol hexose). An analysis by denaturing gradient gel electrophoresis (DGGE) of PCR-amplified bacterial 16S rDNA of the microflora indicated that changes in the microbial community took place at various dilution rates, and these changes appeared to correspond to the changes in product distributions. Sequence analyses of the DGGE fragments revealed the probable major population of the microflora. A band closely related to the microorganisms of thermophilic anaerobic bacteria was detected with strong intensity on both glucose and cellulose. Differences in the production yield of hydrogen could have been caused by different populations of microorganisms in each microflora. In the case of cellulose, increasing the dilution rate brought about an accumulation of microorganisms related to Clostridia species that have cellulolytic activity, this being in accordance with the notion of cellulose decomposition being the rate-limiting reaction.

Base Sequence↗
PubMed2001

Microbial community in anaerobic hydrogen-producing microflora enriched from sludge compost.

Hydrogen production by thermophilic anaerobic microflora enriched from sludge compost was studied by using an artificial medium containing cellulose powder. Hydrogen gas was evolved with the formation of acetate, ethanol, and butyrate by decomposition of the cellulose powder. The hydrogen production yield was 2.0 mol/mol-hexose by either batch or chemostat cultivation. A medium that did not contain peptone demonstrated a lower hydrogen production yield of 1.0 mol/mol-hexose with less formation of butyrate. The microbial community in the microflora was investigated through isolation of the microorganisms by both plating and denaturing gradient gel electrophoresis (DGGE) of the' PCR-amplified V3 region of 16S rDNA. Sixty-eight microorganisms were isolated from the microflora and classified into nine distinct groups by genetic fingerprinting of the PCR-DGGE or by a random amplified polymorphic DNA analysis and determination of the partial sequence of 16S rDNA. Most of the isolates belonged to the cluster of the thermophilic Clostridium/Bacillus subphylum of low G+C gram-positive bacteria. Product formation by most of the isolated strains corresponded to that produced by the microflora. Thermoanaerobacterium thermosaccharolyticium was isolated in the enrichment culture with or without added peptone. and was detected with strong intensity by PCR-DGGE. Two other thermophilic cellulolytic microorganisms, Clostridium thermocellum and Clostridium cellulosi, were also detected by PCR-DGGE, although they could not be isolated. These findings imply that hydrogen production from cellulose by microflora is performed by a consortium of several species of microorganisms.

Anaerobiosis↗
PubMed2001

Defibrinogenating effect of batroxobin (Defibrase) in rats and inhibition of migration of human vascular smooth muscle cells by the plasma of batroxobin-treated rats in vitro.

The defibrinogenating effect of batroxobin (Defibrase) in male Wistar rats and the inhibitory effects of the plasma of batroxobin-treated rats on the migration of human vascular smooth muscle cells (SMCs) were investigated in vitro. At 1 h after a single intravenous injection of 3.0, 10.0 or 30.0 BU/kg batroxobin (ten rats in each group), the fibrinogen levels in the plasma of the rats decreased to 88.3, 66.2 and 16.5%, respectively, of that in the plasma of control saline-treated rats (261.0+/-26.7 mg/dl). When the plasma from the batroxobin-treated rats was added to Dulbecco's modified Eagle's medium at a concentration of 0.2% for a vascular SMC migration assay and incubated in a modified Boyden's chamber system at 37 degrees C for 24 h, significant inhibitory effects on vascular SMC migration were observed in the 10.0 (P<0.05) and 30.0 BU/kg (P<0.01) batroxobin-treated rats. The plasma of batroxobin-treated rats as well as standard rat fibrinogen induced vascular SMC migration in a fibrinogen content-dependent manner except the plasma of the 30.0 BU/kg batroxobin-treated rats. Moreover, the rat serum (0.1 approximately 5.0%) did not show any activity on vascular SMC migration in the present experimental system. These results indicate that the plasma fibrinogen significantly influences vascular SMC migration, and that the inhibitory effect of the plasma of batroxobin-treated rats on vascular SMC migration is related to the defibrinogenating action of batroxobin in vivo.

Animals↗
PubMed2001

Lectin histochemistry of glycoconjugates in the feline hair follicle and hair.

The distribution of glycoconjugate in the feline hair follicle and hair was studied by light and electron microscopic histochemical methods. The hair apparatus was found to contain considerable amounts of complex carbohydrates with different saccharide residues (alpha-D-mannose, beta-D-glucose, alpha-L-fucose, beta-N-acetyl-D-glucosamine). Variations of those were detected in the plasma membrane of the hair follicle cells during the course of their differentiation and keratinization, namely, alph-D-glucose, alpha-L-fucose and beta-N-acetyl-D-glucosamine in the suprabulbar and bulbar regions. The reaction level of sialic acid residues in the plasma membrane decreased in some cell layers during the course of differentiation. The results obtained from the present study indicated that interaction between saccharide residues of neutral carbohydrates and sialyl groups during the anagen phase might contribute to cell keratinization in hair follicles and hairs. It is discussed whether the existence of glycogen in outer root sheath cells might enable these cells to provide other hair apparatus cells with energy when necessary. Moreover, it became obvious from variations in sialyl residue distribution that cell differentiation processes terminate first of all in Huxley's and Henle's layers within the suprabulbar region of the hair follicle, as followed by the hair cortex.

Animals↗
PubMed2001

Stimulation of tetrahydrobiopterin synthesis induced by insulin: possible involvement of phosphatidylinositol 3-kinase.

Although we recently showed that insulin increases the intracellular concentration of tetrahydrobiopterin (BH4), which is one of the cofactors of nitric oxide (NO) synthase, the mechanism of the effect was not elucidated. In the present study, we examined the signaling pathway of the stimulation of BH4 synthesis by insulin in mouse brain microvascular endothelial cells. Extracellular and intracellular BH4 levels were determined as biopterin by using reversed-phase high performance liquid chromatography with fluorometric detection. Measurement of the level of mRNA for GTP cyclohydrolase I (GTPCH), which is the rate-limiting enzyme for de novo BH4 synthesis, was performed by reverse transcription-polymerase chain reaction (RT-PCR). Addition of insulin to endothelial cells caused an increase of not only the intracellular but also the extracellular BH4 level in a time- and a concentration-dependent manner. Insulin also induced an increase of the level of GTPCH mRNA. Moreover, 2,4-diamino-6-hydroxypyrimidine, an inhibitor of GTPCH, inhibited the insulin-induced enhancement of BH4 synthesis. The increase in the BH4 level and the induction of GTPCH mRNA by insulin were reduced by wortmannin and LY294002, which are both phosphatidylinositol 3-kinase (PI3-kinase) inhibitors. These results suggest that insulin stimulates BH4 synthesis through the de novo synthetic pathway involving induction of GTPCH, and that the signaling pathway involves the activation of PI3-kinase.

Animals↗
PubMed2001

HBe seroconversion and HBs mutation among Japanese hepatitis B virus carriers.

It has been reported in Germany that seroconversion to anti-HBe or anti-HBs is frequently associated with genotype changes of hepatitis B virus (HBV) from genotype A to genotype D. We previously reported that the HBeAg-negative state in Japan was significantly more common in patients infected with genotype B HBV than those infected with genotype C HBV. To determine whether the high prevalence of genotype B in the HBeAg-negative state is due to a change from genotype C to genotype B, 72 pairs of serum samples before and after HBe seroconversion were examined for nucleotide sequences in the S gene (amino acids 42-164) among Japanese HBV carriers. No one was identified to have undergone genotype change during HBe seroconversion. A total of 71 codon mutations were observed. Sixty-two of these 71 codon mutations (87.3%) were non-synonymous. Genotype B HBV had no mutational hot spots. In genotype C, there was a mutational hot spot at amino acid 126 of the S protein, and it was suggested that Thr126 before HBe seroconversion was more susceptible to becoming an asymptomatic carrier after HBe seroconversion than Ile126. In conclusion, genotype changes during HBe seroconversion were not found to be common in Japan.

Journal Article↗
PubMed2001

Determinants on tmRNA for initiating efficient and precise trans-translation: some mutations upstream of the tag-encoding sequence of Escherichia coli tmRNA shift the initiation point of trans-translation in vitro.

tmRNA facilitates a novel translation, trans-translation, in which a ribosome can switch between translation of a truncated mRNA and the tmRNA's tag sequence. The mechanism underlying resumption of translation at a definite position is not known. In the present study, the effects of mutations around the initiation point of the tag-encoding sequence of Escherichia coli tmRNA on the efficiency and the frame of tag translation were assessed by measuring the incorporations of several amino acids into in vitro poly (U)-dependent tag-peptide synthesis. One-nucleotide insertions within the tag-encoding region did not shift the frame of tag translation. Any 1-nt deletion within the span of -5 to -1, but not at -6, made the frame of tag translation heterologous. Positions at which a single base substitution caused a decrease of trans-translation efficiency were concentrated within the span of -4 to -2. In particular, an A-4 to C-4 mutation seriously damaged the trans-translation, although this mutant retained normal aminoacylation and ribosome-binding abilities. A possible stem and loop structure around this region was not required for transtranslation. It was concluded that the tag translation requires the primary sequence encompassing -6 to +11, in which the central 3 nt, A-4, G-3, and U-2, play an essential role. It was also found that several base substitutions within the span of -6 to -1 extensively shifted the tag-initiation point by -1.

Acylation↗
PubMed2001

Convenient synthesis of aliphatic polyesters by distannoxane-catalyzed polycondensation.

A convenient synthesis of aliphatic polyesters by the distannoxane-catalyzed polycondensation of aliphatic dicarboxylic acids and aliphatic diols in solvents under azeotropic conditions was developed. To determine the optimum conditions for polycondensation of succinic acid with 1,4-butandiol, the effect of various types of catalyst and their concentration was investigated. By choosing the appropriate solvent, the polymerization was made to proceed in a two-phase system of solvent and molten polymer, and in the presence of 0.001 mol % of 1-chloro-3-hydroxy-1,1,3,3-tetrabutyldistannoxane (CHTD), poly(butylene succinate) (PBS) with a weight-average molecular weight of 277,000 was obtained. This method was then successfully applied to the synthesis of various aliphatic polyesters, such as poly(ethylene succinate), poly(1,4-cyclohexanedimethylene succinate), and poly(ethylene sebacate).

Biodegradation, Environmental↗
PubMed2001

Granulomatous slack skin: an ultrastructural study.

BACKGROUND: Granulomatous slack skin is a rare lymphoproliferative disorder characterized clinically by gradual development of pendulous folds of lax erythematous skin in flexural areas, and histologically by non-necrotizing granuloma, with numerous multinucleated giant cells, mononuclear histiocytes, and atypical lymphocytes associated with loss of elastic fibers. Although there are many reports describing the histological and immunophenotypic features of this disease, only a few have described the ultrastructural features. METHODS: Here we report a case of granulomatous slack skin and describe the ultrastructural findings. RESULTS AND CONCLUSION: We could detect some previously not noted abnormal findings in multinucleated giant cells, histiocytes, and atypical lymphocytes.

Adult↗
PubMed2001

Re-treatment for immune globulin-resistant Kawasaki disease: a comparative study of additional immune globulin and steroid pulse therapy.

BACKGROUND: We compared the efficacy and safety of additional intravenous immune globulin (IVIG) therapy with steroid pulse therapy in patients with IVIG-resistant Kawasaki disease. METHODS: Two-hundred and sixty-two consecutive patients had been treated with a single dose of IVIG (2 g/kg) and aspirin (30 mg/kg per day). Thirty-five patients (13.4%) were not clinical responders to the initial IVIG treatment. They received an additional IVIG treatment (1 g/kg) within 48 h after the initial treatment. Seventeen patients (6.5%) did not respond to the additional IVIG treatment. We randomly divided these patients into two groups: group 1 consisted of eight patients who were treated with a single additional dose of IVIG (1 g/kg), while group 2 consisted of nine patients who were treated with steroid pulse therapy. RESULTS: The IVIG-resistant patients had a high incidence of coronary artery lesions (CAL; 48.6%). Five patients (62.5%) in group 1 had CAL, including two patients who each had a giant aneurysm and three patients who each had a small aneurysm. Seven patients (77.8%) in group 2 had CAL, including two patients who each had a giant aneurysm, two patients who each had a small coronary aneurysm and three patients who each showed transient dilatation during steroid pulse therapy. There was no significant difference in the incidence of CAL between the two groups. The duration of high fever in group 2 (1.4~0.7 days) was significantly shorter than in group 1 (4.8~3.4 days; P<0.05). The medical costs for the treatment of patients in group 2 (113, 012 yen +/- 22,084) were significantly lower than those for group 1 (144,194 yen +/- 12,914; P<0.05). CONCLUSIONS: Steroid pulse therapy may be useful in the treatment of patients with IVIG-resistant Kawasaki disease who experience prolonged fever. However, transient dilatation of the coronary artery is observed during steroid pulse therapy, so careful echocardiographic examination should be performed for those patients receiving steroid pulse therapy for the sake of early detection of coronary artery abnormalities.

Anti-Inflammatory Agents↗
PubMed2001

Catheter closure of moderate to large sized patent ductus arteriosus using the simultaneous double or triple coil technique.

BACKGROUND: Although the clinical experience with transcatheter closure of the patent ductus arteriosus using the coils has grown rapidly, one important complication of this procedure using the conventional Gianturco coil was the migration of coils into peripheral vessels. This is especially for patients with a relatively larger size ductus and the risk for such complications could be increased. In this situation, the detachable coil may have some technical benefits to perform coil occlusion and reduce the incidence of complications. METHODS: We describe the clinical efficacy of a simultaneous double or triple coil occlusion technique using the Cook detachable coil or bioptome delivered 0.052 inch Gianturco coil to close the ductus arteriosus. This was performed in patients whose ductus diameter was greater than 3.0 mm. RESULTS: From February 1995 to December 2000, 118 patients with patent ductus arteriosus were treated by coil occlusion using Cook detachable coils, of whom 58 patients whose minimum diameter of ductus > or = 3.0 mm were reviewed. All patients had successful placement of coils. According to the evaluation by color flow mapping, a trivial shunt was observed in 17 patients (29%) within 24 h after the procedure. In 11 out of 17 patients, a residual shunt was not detected 1 month after the procedure. At 6 months after the procedure, the residual shunt was detected only in three patients. CONCLUSIONS: Although this study did not calculate the statistical significance between detachable and non-detachable coils in term of occlusion rate, our institutional experience suggests that the simultaneous double or triple coil technique using the detachable or 0.052 inch Gianturco coils can reduce the prevalence of coil migration or complications.

Adolescent↗
PubMed2001

Guidelines for catheter intervention in coronary artery lesion in Kawasaki disease.

The Research Committee of Ministry of Health, Labour and Welfare 'Study of treatment and long-term management in Kawasaki disease' reported the guidelines for catheter intervention in coronary artery lesion in Kawasaki disease in this paper. The contents include: (i) background and natural history of coronary artery lesion in Kawasaki disease; (ii) indication of catheter intervention; (iii) types of procedure, and their indication and care; (iv) institute and backup system; (v) the management after procedure, evaluation and follow up; and (vi) prospects, especially in relation to bypass surgery.

Angioplasty, Balloon, Coronary↗
PubMed2001

A novel approach to endoscopic colorectal mucosal resection using a three-channel outer tube and multiple forceps: an experimental assessment.

BACKGROUND AND STUDY AIMS: Colorectal endoscopic mucosal resection (EMR) has limitations both anatomically and technically when it is done using the conventional snare wire method. The aim of this study was to develop a new method and instrument for colorectal EMR. METHODS: A total of 21 EMR procedures were done using ten surgical specimens. Saline was injected into the normal submucosa of freshly resected colorectal specimens to prepare a pseudotumor. EMR was performed experimentally by employing a three-channel outer tube with three forceps and a colonoscope with a needle-type precutting knife. This method was assessed in terms of safety and the size of the resected specimens. RESULTS: Perforation occurred only twice in the initial stage of this study. The size of the specimens resected by EMR was 28-39 mm (long diameter 34.8+/-3.11), by 22-28 mm (short diameter 25.8+/-2.07). CONCLUSION: This method can achieve safety and en bloc mucosal resection to the submucosal layer. This novel approach may be promising for clinical application as a new form of endoscopic surgery.

Colonoscopes↗