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Biomedical subjects

C Ishii

Publications and source records attributed to C Ishii.

At least 19 recordsLinked to original sources
PubMed2003

Relationship between transcardiac gradient of endothelin-1 and left ventricular remodelling in patients with first anterior myocardial infarction.

Aims To evaluate whether plasma endothelin-1 (ET-1) is extracted or produced through the heart in patients with acute myocardial infarction (AMI), and the relationship between transcardiac extraction of plasma ET-1 and left ventricular (LV) remodelling. Methods and results We measured the plasma level of ET-1 in the aortic root (Ao) and coronary sinus (CS) in 48 consecutive patients, who received successful revascularization and enalapril, for a first anterior AMI. In the acute phase the plasma ET-1 level was significantly higher both in the Ao and the CS compared to the control subjects. However, the plasma ET-1 level was significantly lower in the CS than in the Ao in the acute phase and after 1 month. There were significant correlations between transcardiac extraction of ET-1 in the acute phase and LV ejection fraction and LV end-diastolic volume index (LVEDVI) after 1 month. Stepwise multivariate analysis showed that maximal creatine phosphokinase and transcardiac extraction of plasma ET-1 during the acute phase were independently and positively correlated with the absolute change in LVEDVI after 1 month. Conclusions These results indicate that elevated circulating ET-1 is extracted through the heart in patients with a first anterior AMI and that the extracted ET-1 plays a significant role in modulating post-infarct LV remodelling.

Atrial Natriuretic Factor↗
PubMed2002

The upr-1 gene encodes a catalytic subunit of the DNA polymerase zeta which is involved in damage-induced mutagenesis in Neurospora crassa.

The upr-1 mutant was one of the first mutagen-sensitive mutants to be isolated in Neurospora crassa. However, the function of the upr-1 gene has not yet been elucidated, although some genetic and biochemical data have been accumulated. In order to clone the upr-1 gene, we performed a chromosome walk from the mat locus, the closest genetic marker to upr-1 for which a molecular probe was available, towards the centromere, and a chromosomal contig of about 300-400 kb was constructed. Some of these clones complemented the temperature sensitivity of the un-16 mutation, which is located between mat and upr-1. The un-16 gene was sequenced, and localized in the MIPS Neurospora crassa genome database. We then searched the regions flanking un-16 for homologs of known DNA repair genes, and found a gene homologous to the REV3 gene of budding yeast. The phenotype of the upr-1 mutant is similar to that of the yeast rev3 mutant. An ncrev3 mutant carrying mutations in the N. crassa REV3 homolog was constructed using the RIP (repeat-induced point mutation) process. The spectrum of mutagen sensitivity of the ncrev3 mutant was similar to that of the upr-1 mutant. Complementation tests between the upr-1 and ncrev3 mutations indicated that the upr-1 gene is in fact identical to the ncrev3 gene. To clarify the role of the upr-1 gene in DNA repair, the frequency of MMS and 4NQO-induced mutations was assayed using the ad-8 reversion test. The upr-1 mutant was about 10 times less sensitive to both chemicals than the wild type. The expression level of the upr-1 gene is increased on exposure to UV irradiation in the uvs-2 and mus-8 mutants, which belong to postreplication repair group, as well as in the wild type. All these results suggest that the product of the upr-1 gene functions in damage-induced mutagenesis and DNA translesion synthesis in N. crassa.

Catalytic Domain↗
PubMed2001

Diabetic ketoacidosis in a case of pheochromocytoma.

A 31-year-old woman was admitted to our hospital because of diabetic ketoacidosis (DKA). Ultrasound sonography revealed the existence of the left adrenal tumor and endocrinological examinations established a diagnosis of pheochromocytoma. She had been healthy and there was no evidence for gestational diabetes in her personal history. Characteristic features were not found in her tumor size and the catecholamine levels as compared with typical cases of pheochromocytoma. An overwhelming secretion of catecholamine might suppress insulin secretion, as evidenced by the improvement after the resection of the tumor. However, a significant insulin resistance continued after tumor resection. Obesity and the heterozygosity of beta3-adrenergic receptor gene (Try64Arg) might play a role in insulin resistance, which resulted in DKA at least in part. Literature survey revealed four cases of DKA in the patients with pheochromocytoma including ours, three of which were Japanese. Pancreatic capacity to secrete insulin has been reported to be less than Caucasians, which might be another reason for DKA. Thus, we speculate that both suppressed insulin secretion and insulin resistance deteriorated by obesity or other factor(s) such as abnormality in beta3 adrenergic receptor probably depress beta-cell function resulting in abnormal metabolic imbalance such as DKA.

Adrenal Gland Neoplasms↗
PubMed2000

Detection of DNA restriction fragment polymorphisms in Streptococcus equi.

Large-restriction-fragment (LRF) polymorphisms in Streptococcus equi (S equi subspecies equi) were studied by pulsed-field gel electrophoresis. Five or six chromosomal fragments of between 194 and 915 kb were separated by digestion with the restriction endonuclease Notl. All 20 isolates of S equi, including 12 from independent Japanese outbreaks, four from independent American outbreaks, two from a single Irish outbreak, us vaccine strain F43, and type strain NCTC 9682 were successfully typed. Seven distinctive, reproducible and stable types were identified. The 12 Japanese isolates collected between 1992 and 1998 were of LRF type II suggesting that they were derived from the same source. The remaining eight isolates were of six types. The results indicate that LRF typing should be a useful technique for investigating the source and transmission of S equi.

Animals↗
PubMed2000

Characterization of the Neurospora crassa mus-25 mutant: the gene encodes a protein which is homologous to the Saccharomyces cerevisiae Rad54 protein.

Characterization of the Neurospora crassa mus-25 mutant suggests that it is defective in recombination repair and belongs to the uvs-6 epistasis group. It shows a high sensitivity to the alkylating agents methyl methanesulfonate (MMS) and N-methyl-N'-nitro-N-nitrosoguanidine (MNNG), but not to UV radiation. It is barren (i.e. does not produce ascospores) in homozygous crosses. The frequency of MMS-induced mutations at the ad-3 loci is approximately three times higher than in the wild type. The ratio of homologous to nonhomologous integration of the pMTR::HYG plasmid is much lower than in wild type. The mus-25 mutant is epistatic to the mei-3 mutant for MMS sensitivity. mei-3, which is a homololog of the Saccharomyces cerevisiae gene RAD51, is a member of the uvs-6 epistasis group which contains several genes that are homologous to recombination repair genes in other organisms. The mus-25 gene was cloned by identifying a genomic DNA fragment which complements the MMS sensitivity of the mutant. The amino acid sequence deduced from the cloned DNA showed a high degree of homology to the Rad54 protein, which is involved in recombinational repair in S. cerevisiae. Comparison of the nucleotide sequences of the genomic and cDNAs of the mus-25 gene revealed an ORF of 2505 bp with a single 118-bp intron beginning immediately after the second nucleotide of the AUG start codon. The molecular weight of the deduced gene product was 93.5 kDa. The transcript level was raised within 60 min after UV irradiation or MMS treatment, as also observed for the expression of the other N. crassa recombinational repair genes, suggesting the existence of a common mechanism which induces expression of the recombinational repair genes in response to DNA damage.

Alkylating Agents↗
PubMed2000

A Neurospora double-strand-break repair gene, mus-11, encodes a RAD52 homologue and is inducible by mutagens.

We isolated a Neurospora crassa cDNA that encodes a Rad52 homologue (ncRAD52) by PCR, using degenerate primers. RFLP mapping demonstrated that the cloned gene is located close to the ro-4 locus on the right arm of linkage group V (LGVR). In a second experiment, we used sib selection to identify a cosmid clone containing the mus-11 gene in a N. crassa genomic library. Fine-scale mapping of the mus-11 mutant showed the gene order on LGVR near ro-4 to be: ad-7 - (9.5 mu) - pab-2 (7.8 mu) - mus-11 - (3.7 mu) - inv. The nucleotide sequence of the mus-11 gene matched that of the ncRAD52 cDNA. Thus, the mus-11 gene encodes the Rad52 homologue. The deduced amino acid sequence of the MUS11 protein shows 32.0% and 27.5% overall identity to the Schizosaccharomyces pombe Rad22 protein and the human hRad52 protein, respectively, and a higher level of identity (55-66%) within the conserved N-terminal region (141 residues). The MUS11 protein shows homology to Rad52 from budding yeast only within the N-terminal region (53.2% identity over 141 amino acids) which is conserved among Rad52 homologues. Yeast two-hybrid analysis reveals that the MUS11 protein binds to both the MEI-3 protein, a Rad51 homologue, and to itself in vivo. An ncRAD52 mutant obtained by the RIPping procedure showed the same sensitivity as the original mus-11 mutant to the following mutagens and chemicals: UV light, 4NQO (4-nitroquinoline 1-oxide), MMS (methyl methanesulfonate), EMS (ethyl methanesulfonate), MNNG (N-methyl-N'-nitro-N-nitrosoguanidine), TBHP (tert-butyl hydroperoxide), HU (hydroxyurea) and histidine. Unlike the RAD52 transcript in Saccharomyces cerevisiae, the mus-11 transcript could not be detected in mycelium under normal growth conditions, but expression of the gene was induced by UV irradiation or treatment with MMS.

Amino Acid Sequence↗
PubMed1999

High-resolution structure of the conger eel galectin, congerin I, in lactose-liganded and ligand-free forms: emergence of a new structure class by accelerated evolution.

BACKGROUND: Congerin I is a member of the galectin (animal beta-galactoside-binding lectin) family and is found in the skin mucus of conger eel. The galectin family proteins perform a variety of biological activities. Because of its histological localization and activity against marine bacteria and starfish embryos, congerin I is thought to take part in the eels' biological defense system against parasites. RESULTS: The crystal structure of congerin I has been determined in both lactose-liganded and ligand-free forms to 1. 5 A and 1.6 A resolution, respectively. The protein is a homodimer of 15 kDa subunits. Congerin I has a beta-sheet topology that is markedly different from those of known relatives. One of the beta-strands is exchanged between two identical subunits. This strand swap might increase the dimer stability. Of the known galectin complexes, congerin I forms the most extensive interaction with lactose molecules. Most of these interactions are substituted by similar interactions with water molecules, including a pi-electron hydrogen bond, in the ligand-free form. This observation indicates an increased affinity of congerin I for the ligand. CONCLUSIONS: The genes for congerin I and an isoform, congerin II, are known to have evolved under positive selection pressure. The strand swap and the modification in the carbohydrate-binding site might enhance the cross-linking activity, and should be the most apparent consequence of positive selection. The protein has been adapted to functioning in skin mucus that is in direct contact with surrounding environments by an enhancement in cross-linking activity. The structure of congerin I demonstrates the emergence of a new structure class by accelerated evolution under selection pressure.

Amino Acid Sequence↗
PubMed1999

Characterization of a Neurospora crassa photolyase-deficient mutant generated by repeat induced point mutation of the phr gene.

We produced a photolyase-deficient mutant by repeat induced point mutation using the Neurospora crassa photolyase gene cloned previously. This mutation identified a new gene, phr, which was mapped on the right arm of linkage group I by both RFLP mapping and conventional mapping. To investigate the relationship between photoreactivation and dark repair processes, especially excision repair, double mutants of phr with representative repair-defective mutants of different types were constructed and tested for UV sensitivity and photoreactivation. The results show that the phr mutation has no influence on dark repair. Tests with CPD and TC(6-4) photoproduct-specific antibodies demonstrated that the phr mutant is defective in CPD photolyase and confirmed that there is no TC(6-4) photolyase activity in N. crassa. Furthermore, N. crassa photolyase is not a blue light receptor in the signal transduction that induces carotenoid biosynthesis.

Blotting, Southern↗
PubMed1999

PPAR gamma mediates high-fat diet-induced adipocyte hypertrophy and insulin resistance.

Agonist-induced activation of peroxisome proliferator-activated receptor gamma (PPAR gamma) is known to cause adipocyte differentiation and insulin sensitivity. The biological role of PPAR gamma was investigated by gene targeting. Homozygous PPAR gamma-deficient embryos died at 10.5-11.5 dpc due to placental dysfunction. Quite unexpectedly, heterozygous PPAR gamma-deficient mice were protected from the development of insulin resistance due to adipocyte hypertrophy under a high-fat diet. These phenotypes were abrogated by PPAR gamma agonist treatment. Heterozygous PPAR gamma-deficient mice showed overexpression and hypersecretion of leptin despite the smaller size of adipocytes and decreased fat mass, which may explain these phenotypes at least in part. This study reveals a hitherto unpredicted role for PPAR gamma in high-fat diet-induced obesity due to adipocyte hypertrophy and insulin resistance, which requires both alleles of PPAR gamma.

Adipocytes↗
PubMed1999

Interplay between chromosomal beta-lactamase and the MexAB-OprM efflux system in intrinsic resistance to beta-lactams in Pseudomonas aeruginosa.

We investigated the role of chromosomal beta-lactamase and the MexAB-OprM efflux system in intrinsic resistance to beta-lactams in Pseudomonas aeruginosa. Determination of the susceptibilities of a series of isogenic mutants with impaired production of the beta-lactamase and the efflux system to 16 beta-lactams including penicillins, cephems, oxacephems, carbapenems, and a monobactam demonstrated that the intrinsic resistance of P. aeruginosa to most of the beta-lactams is due to the interplay of both factors.

Drug Resistance, Microbial↗
PubMed1999

Accelerated evolution in the protein-coding region of galectin cDNAs, congerin I and congerin II, from skin mucus of conger eel (Conger myriaster).

Two cDNAs encoding galectins named congerins I and II from the skin mucus of conger eel (Conger myriaster) were isolated and sequenced. Comparison of the nucleotide sequences of congerins I and II showed that the sequence similarities of the 5' and 3' untranslated regions (86 and 88%, respectively) were much higher than those of the protein-coding region (73%). The numbers of nucleotide substitutions per site (KN) for the untranslated regions are smaller than the numbers of nucleotide substitutions per synonymous site (KS) for the protein coding region. Furthermore, nonsynonymous nucleotide substitutions have accelerated more frequently than synonymous nucleotide substitutions in the protein coding region (KA/KS = 2.57). These results suggest that accelerated substitutions have occurred in the protein-coding regions of galectin genes to generate diverse galectins with different molecular properties. Northern blot analysis showed that both congerins were expressed not only in the skin tissues but also in the stomach of conger eel.

Amino Acid Sequence↗
PubMed1999

[Combination effect of teicoplanin and panipenem on highly resistant strains of MRSA].

We investigated the in vitro combination effect of teicoplanin (TEIC) and panipenem (PAPM) on highly oxacillin-resistant strains of Staphylococcus aureus (MRSA) isolated from various clinical specimens. Combination of TEIC and PAPM using checkerboard titration technique by agar dilution exhibited an excellent effect with mean fractional inhibitory concentration index of 0.18 +/- 0.07 on 47 MRSA strains, and the effects were judged as synergistic against all of the strains tested. In the combination of TEIC and PAPM at 1/4 MIC each against exponentially growing cells of MRSA, good bactericidal activity was found when TEIC and PAPM were added simultaneously, and PAPM was added at 1 or 2 hours prior to addition of TEIC, although the bactericidal activity was scarcely demonstrated when TEIC was added at 1 or 2 hours prior to addition of PAPM. Bactericidal activity against MRSA was enhanced in the combination of TEIC and PAPM at 1/4 MIC each for MRSA than the bactericidal activity of TEIC at 1 MIC alone. TEIC alone showed no bactericidal activity against P. aeruginosa in the mixed cultures with MRSA, while strong bactericidal activity against P. aeruginosa was induced by PAPM. In vitro bactericidal activities against mixed cultures of MRSA with P. aeruginosa were evaluated under conditions of concentrations of TEIC and PAPM, alone and in combination, whose plasma concentrations in human were simulated by a pharmacokinetic simulation model. Bactericidal activity against MRSA was enhanced by the combination of TEIC at 200 mg twice or once daily with PAPM at 500 mg twice daily in comparison with the bactericidal activity of each antibiotic alone, and P. aeruginosa was killed by the antibacterial activity of PAPM.

Anti-Bacterial Agents↗
PubMed1999

[In vitro and in vivo activities of cefpodoxime proxetil against penicillin-resistant Streptococcus pneumoniae].

We evaluated in vitro and in vivo activities of cefpodoxime proxetil (CPDX-PR) in comparison with other oral beta-lactams, cefdinir (CFDN), cefditoren pivoxil (CDTR-PI), and faropenem (FRPM), against penicillin-susceptible and -resistant Streptococcus pneumoniae. In vitro activities (MICs) of CPDX, CFDN, CDTR, and FRPM against clinical isolates, penicillin-susceptible S. pneumoniae (PSSP: MIC of penicillin G, < or = 0.063 microgram/ml), penicillin-intermediate S. pneumoniae (PISP: MIC of penicillin G, 0.125-1 microgram/ml), and penicillin-resistant S. pneumoniae (PRSP: MIC of penicillin G, > or = 2 micrograms/ml), were tested by an agar dilution method. The MIC80s of CPDX against 27 PSSP strains, 23 PISP strains, and 23 PRSP strains were 0.032, 1, and 8 micrograms/ml, respectively, which were superior to or equal to those of CFDN (0.063, 4, and 8 micrograms/ml) and were inferior to those of CDTR (0.016, 0.5, and 1 microgram/ml) and FRPM (< or = 0.008, 0.25, and 1 microgram/ml). Infection was induced in mice by inoculating with a PRSP clinical isolate, 9605 or 9601 (serotype 6), or 10692 (serotype 19), through the nares of male ddY mice into the lungs. The mice were treated with drugs with doses of 2-50 mg/kg at 18, 26, 42, and 50 hours after the infection. Viable cell numbers in the lungs and blood were assayed at 66 hours after the infection. The efficacy of each drug was dose-dependent. CPDX-PR showed the most potent in vivo efficacy among the drugs tested against the infections caused by the PRSP strains. MICs of the drugs against PRSP 9605, 9601, and 10692 were as follows: CPDX, 4, 4 and 2 micrograms/ml; CFDN, 16, 16, and 4 micrograms/ml; CDTR, 1, 1, and 0.5 microgram/ml; and FRPM, 1, 0.5, and 0.5 microgram/ml, respectively. Thus, CPDX-PR showed a stronger in vivo activity than that expected from the MICs of CPDX. This was probably caused by the pharmacokinetic advantage of CPDX over the other drugs used in this study.

Animals↗
PubMed1998

Intrasolid Interfacial Fractality of a Less-Crystalline Solid.

Small angle X-ray scattering (SAXS) measurements have been carried out on pitch (PIT) and cellulose (CEL)-based activated carbon fibers (ACFs). In the higher angle region, the scattering intensity did not obey the classical Porod's law. This suggests that ACFs have a rough surface and their roughness is expressed by the concept of surface fractal. The surface fractal dimension was determined from SAXS for each ACF. ACFs were treated at high temperature in argon in order to control the nanographitic crystallinity. PIT and CEL lost their microporosity upon heat treatment above 1773 and 2073 K, respectively. These nonporous ACFs showed also a strong SAXS caused by the electron density difference at the interface between microcrystalline and amorphous phase. This interface also had a fractal dimension, which was defined as the interfacial fractal dimension. The surface or interfacial fractal dimension of ACF depended on the heating temperature. As the treating temperature increased, the surface or interfacial fractal dimension decreased from 2.8 to 2.0. Both PIT and CEL showed a similar temperature dependence on each other. The surface or interfacial fractal dimension was reduced with the growth of nanographites, and upon heating at 3173 K, the intrasolid interfacial fractal dimension became 2. Copyright 1998 Academic Press.

Journal Article↗
PubMed1998

A new UV-sensitive mutant that suggests a second excision repair pathway in Neurospora crassa.

In an attempt to understand the relationship between photorepair and dark repair in Neurospora crassa, a new mutant was isolated, which showed defects in both repair processes. The new mutant, mus-38, is moderately sensitive to UV and shows imperfect photoreactivation following UV irradiation. DNA was purified from this mutant and the other UV-sensitive mutants, and analyzed for the removal of cyclobutane pyrimidine dimers (CPDs). UV-specific endonuclease-sensitive sites (ESS) completely disappeared with 1 h of photoreactivation in mus-38 DNA, although the survival recovery with photoreactivation was greatly reduced in this mutant. This suggests that the insufficient survival recovery with photoreactivation in mus-38 does not result from a failure of photo-reversal of CPDs. Removal of ESS during liquid holding (dark repair) was slower in mus-38 compared to wild type. To test the possibility that this mutant was involved in excision repair, the double mutant was made between mus-38 and mus-18, which encodes a UV-damage-specific endonuclease. CPD excision in the mus-18 null mutant was severely affected but not completely inhibited. The double mutant showed a complete loss of the excision activity and was super sensitive to UV. These results indicate that mus-38 participates in an excision pathway that is different from the mus-18 pathway. The mus-38 mutant was sensitive not only to UV but also to some chemical mutagens which make adducts on DNA. Thus, mus-38 is possibly involved in an excision-repair pathway that is related to the Saccharomyces cerevisiae RAD3 pathway.

DNA Repair↗
PubMed1998

Phenotypic discordance in monozygotic twins with 22q11.2 deletion.

We report on male monozygotic twins with 22q11.2 deletion and discordant phenotypes. The twins had twin-to-twin transfusion syndrome. Twin 1, the smaller of the pair, had Tetralogy of Fallot, a characteristic facial appearance, swallowing dysfunction, anal atresia, short stature, and mental retardation, whereas twin 2 had a characteristic facial appearance but no other signs of the 22q11 deletion syndrome. Fluorescence in situ hybridization analysis showed a microdeletion on chromosome 22q11.2 in both twins. Zygosity analysis gave a probability of monozygosity greater than 99.999%. These observations indicate that environmental factors or postzygotic events play a role in the phenotypic variability in the twins.

Abnormalities, Multiple↗