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Y Aoki

Publications and source records attributed to Y Aoki.

At least 37 records · Page 2Linked to original sources
PubMed2003

Evidence for unconventional strong-coupling superconductivity in PrOs4Sb12: an Sb nuclear quadrupole resonance study.

We report Sb-NQR results which evidence a heavy-fermion (HF) behavior and an unconventional superconducting (SC) property in Pr(Os4Sb12 with T(c)=1.85 K. The temperature (T) dependence of nuclear-spin-lattice-relaxation rate, 1/T(1), and NQR frequency unravel a low-lying crystal-electric-field splitting below T0 approximately 10 K, associated with Pr3+(4f(2))-derived ground state. In the SC state, 1/T(1) shows neither a coherence peak just below T(c) K nor a T3-like power-law behavior observed for anisotropic HF superconductors with the line-node gap. The isotropic energy gap with its size Delta/k(B)=4.8 K seems to open up across T(c) below T(*) approximately 2.3 K. It is surprising that Pr(Os4Sb12 looks like an isotropic HF superconductor-it may indeed argue for Cooper pairing via quadrupolar fluctuations.

Journal Article↗
PubMed2003

Protein levels of genes encoded on chromosome 21 in fetal Down syndrome brain: challenging the gene dosage effect hypothesis (Part I).

Down syndrome (DS) is the most significant genetic disorder with mental retardation and is caused by trisomy 21. The phenotype of DS is thought to result from overexpression of a gene(s) located on the triplicated chromosome (region). An increasing body of evidence that challenge this "gene dosage effect" hypothesis, however, has been reported indicating that this hypothesis still remains to be elucidated. The availability of the complete sequence of genes on chromosome 21 could have an immediate impact on DS research, but no conclusions can be drawn from nucleic acid levels. This made us evaluate protein levels of six proteins, gene products, encoded on chromosome 21 (T-cell lymphoma invasion and metastasis inducing Tiam1 protein, holocarboxylase synthetase, human interferon-regulated resistance GTP-binding protein MxA, Pbx regulating protein 1, autoimmune regulator, and pericentrin) in fetal cortex from DS and controls at 18-19 weeks of gestational age using Western blot technique. None of the investigated proteins showed overexpression in DS compared to controls. Our present data showing unaltered expression of six proteins on chromosome 21 in fetal DS brain suggest that the existence of the trisomic state is not involved in abnormal development of fetal DS brain and that the gene dosage effect hypothesis is not sufficient to fully explain the DS phenotype. We are in the process of quantifying all gene products of chromosome 21 and our first results do not support the gene dosage hypothesis.

Blotting, Western↗
PubMed2003

Effects of 3,3',4,4',5-pentachlorobiphenyl, a coplanar polychlorinated biphenyl congener, on cultured neonatal mouse testis.

3,3',4,4',5-Pentachlorobiphenyl (PCB126), a congener with a planar configuration, has been established to have relatively strong toxicities similar to those of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) via aryl hydrocarbon receptors. We investigated the effects of this coplanar PCB on mammalian early spermatogenesis and steroidogenesis in a mouse neonatal testicular organ culture system. Testes collected from newborn mice were subjected to organ culture in medium containing 0, 10, 100 or 1000 nM PCB126. Histochemical analysis revealed that the BrdU-labeling indices of both spermatogenic cells and Sertoli cells were unchanged in all testis specimens exposed to the coplanar PCB. CYP1A1 and steroidogenic enzymes (P450scc, P450c17, 3beta-HSD and 17beta-HSD) mRNA levels were determined by semiquantitative RT-PCR. The CYP1A1 mRNA level in cultured testis was significantly increased by PCB126 in a dose-dependent manner. Although mRNA levels of 3beta-HSD and 17beta-HSD were unchanged, the P450scc mRNA level was significantly down-regulated by PCB126 in a dose-dependent manner. In contrast, the P450c17 mRNA level was significantly higher in 1000 nM PCB126-exposed testis than in control testis. These results suggest that the coplanar PCB does not alter the proliferative activity of spermatogenic cells and Sertoli cells in neonatal testis, but that it directly affects the expression of steroidogenic enzyme genes.

Animals↗
PubMed2003

Partial response to biotin therapy in a patient with holocarboxylase synthetase deficiency: clinical, biochemical, and molecular genetic aspects.

We report the clinical course and biochemical findings of a 10-year-old, mentally retarded girl with late-onset holocarboxylase synthetase (HCS, gene symbol HLCS) deficiency and only partial response to biotin. On treatment, even with an unusually high dose of 200mg/day, activities of the biotin-dependent mitochondrial carboxylases in lymphocytes remained below 50% of the mean control values. Not only urinary 3-hydroxyisovaleric acid excretion has been persistently elevated, but also plasma and, with even higher concentrations, cerebrospinal fluid 3-hydroxyisovaleric acid have not normalized. The unusual and insufficient response of this patient to biotin treatment can be explained by the effect of the combination of the common HLCS allele IVS10 +5 g>a on one chromosome and a truncating mutation on the other. This case illustrates mechanisms involved in the genotype-phenotype correlation that unequivocally exists in HCS deficiency.

Age of Onset↗
PubMed2003

Strongyloides ratti: the role of interleukin-5 in protection against tissue migrating larvae and intestinal adult worms.

To determine the role of interleukin-5 (IL-5) and eosinophils in protection against Strongyloides ratti, mice treated with anti-IL-5 monoclonal antibody (mAb) were infected with S. ratti larvae. Strongyloides ratti egg numbers in faeces (EPG) in mAb treated mice were higher than those in control mice on days 6 and 7 after inoculation. The numbers of migrating worms in mAb treated mice 36 h after inoculation were higher than those observed in control mice. Intestinal worm numbers in mAb treated mice 5 days after inoculation were higher than those in control mice. These results show that eosinophils effectively protected the host against S. ratti infection by mainly the larval stage in primary infections. The involvement of eosinophils in protection against secondary infection was also examined. Before secondary infection, mice were treated with anti-IL-5 mAb and infected with S. ratti. Patent infections were not observed in either mAb treated or control Ab treated mice. The numbers of migrating worms in the head and lungs of mAb treated mice increased to 60% of that in primary infected mice. Intestinal worms were not found in mAb treated mice or in control mice after oral implantation of adult worms. Eosinophils were therefore mainly involved in protection against tissue migrating worms in secondary infections.

Animals↗
PubMed2003

Dexamethasone accelerates catabolism of leukotriene C4 in bronchial epithelial cells.

Leukotriene (LT)C4, a potent chemical mediator in bronchial asthma, is metabolised to the less active LTE4 via LTD4 in two consecutive reactions catalysed by enzymes of the glutamyl transpeptidase and dipeptidase families. The activities of these catabolic enzymes may be influenced by glucocorticosteroids. This study was conducted to examine whether this inactivation of LTC4 is affected by dexamethasone (DEX) in transformed human bronchial epithelial cells and normal human bronchial epithelial cells. After incubation with DEX for 0-5 days, cells were resuspended in the presence of exogenous LTC4, and conversion of LTC4 to LTE4 was measured using high-performance liquid chromatography. Gamma-glutamyl transpeptidase (GGT) and GGT-related enzyme (GGTRE) messenger ribonucleic acid (mRNA) expression were examined using reverse transcriptase-polymerase chain reaction analysis, and GGT activity by enzyme assay. Conversion to LTE4 was accelerated by DEX pretreatment. GGTRE but not GGT mRNA expression was enhanced after incubation with DEX. The results indicate that dexamethasone transcriptionally upregulates the activity of gamma-glutamyl transpeptidase-related enzyme in human bronchial epithelial cells, which accelerates inactivation of leukotriene C4 via conversion to leukotriene E4. This is a novel mechanism of glucocorticosteroids in human bronchial epithelial cells.

Analysis of Variance↗
PubMed2003

Mid-term prognosis of non-traumatic osteonecrosis of the femoral head.

We followed, prospectively, 77 patients (90 hips) with early-stage, non-traumatic osteonecrosis of the femoral head for a mean period of nine years. At the time of final review, 56 (62%) were symptomatic. Using the Cox model, the initial radiological stage, the progression of staging, the reduction in size of the lesions and the percentage of necrotic volume on MRI were identified as risk factors. Using the Harris score of < 70 or surgery as the endpoint, the cumulative rates of survival were 60.0% at one year, 43.3% at two years, 38.9% at five years and 37.2% at ten years. Survival curves demonstrated that clinical deterioration could occur 90 months after the initial diagnosis, suggesting that asymptomatic patients should be followed carefully for several years. Radiological time-dependent reduction in size without progressive collapse may represent repair even when the collapse is minimal.

Adult↗
PubMed2002

Pneumococcal purulent genual arthritis after allogeneic bone marrow transplantation.

A 21-year-old male patient with non-Hodgkin's lymphoma (diffuse large T-cell type, clinical stage IV) received allogeneic bone marrow transplantation (BMT) from a partially HLA-mismatched unrelated donor in July 1998 and achieved complete remission. Thereafter, he suffered from chronic graft-versus-host disease (GVHD) and was continuously administered immunosuppressive drugs for a long time. Two years after the BMT, he complained of severe pain in the right knee, which was swollen, and was diagnosed as having pneumococcal purulent genual arthritis. He underwent arthroscopic synovectomy and was administered systemic and intra-articular antibiotics, leading to a gradual improvement. Streptococcal infections are often seen in patients in the late phase after allogeneic BMT because of immunodeficiency associated with chronic GVHD and hyposplenism. Most streptococcal infections are respiratory tract infections and septicemia, and there have been very few reports on cases of purulent genual arthritis. Administration of prophylactic antibiotics and control of chronic GVHD, which is a risk factor of pneumococcal infection, seem to be important to prevent purulent genual arthritis.

Adolescent↗
PubMed2002

Circulating CD34+ cells to predict the adequate harvest of peripheral blood progenitor cells in platinum-based chemotherapy.

OBJECTIVE: The aim of this study was to clarify the appropriate timing for peripheral blood progenitor cells (PBPC) harvesting after platinum-based mobilization chemotherapy by measurement of the circulating CD34+ cell concentrations. PATIENTS AND METHODS: PBPC were collected for autotransplantation via a total of 68 leukaphereses in 16 patients with gynecological cancer. Circulating CD34+ cell concentrations were measured by CD34-side scatter parameter analysis. RESULTS: Data could be fitted into a linear regression line described by the equation y = 0.33 + 4.14 x (x) (R2 = 0.256), where y = the number of harvested colony-forming unit granulocyte macrophage (CFU-GM (x10(5)/kg) and x = the percentage of circulating CD34+ cells and y = 1.747 + 44.53 x (x) (R2= 0.475), where y = the number of harvested CD34+ cells (x10(6)/kg) and x = the percentage of circulating CD34+ cells. Failure to mobilize sufficient CFU-GM numbers (>1 x 10(5)/kg) occurred in 29 of 31 leukaphereses when the percentage of circulating CD34+ cells was less than 0.10%. CONCLUSIONS: Harvesting procedure may be avoided when circulating CD34+ cells showed less than 0.10% after platinum-based mobilization chemotherapy.

Adult↗
PubMed2002

Circulating highly fluorescent reticulocytes to predict the adequate harvesting of peripheral blood progenitor cells in platinum-based chemotherapy.

We prospectively evaluated whether peripheral blood progenitor cells (PBPC) yield from a single leukapheresis could be predicted by measurement of circulating highly fluorescent reticulocytes (HFR). PBPC were collected from 46 leukaphereses in 15 patients with gynecological cancer following platinum-based chemotherapy. Once a level of at least 5.0% HFR was achieved, sufficient PBPC were collected in a single harvest in 71% of the procedures. Whereas, failure to mobilize sufficient PBPC occurred in 24 of 28 leukaphereses when the percentage of circulating HFR was less than 5.0%. In conclusion, circulating HFR may aid in the efficiency of PBPC collections in platinum-based chemotherapy.

Adult↗
PubMed2002

DNA analysis of nosocomial infection by Enterobacter aerogenes in three cases of septicaemia in Japan.

Ceftazidime-resistant Enterobacter aerogenes was isolated from blood cultures of three patients with fever. DNA analysis using pulsed-field gel electrophoresis and ribosomal RNA gene restriction digest pattern analysis revealed that the strains were clonally similar to each other with a 79.3-96.0% homology. The same strain of E. aerogenes was isolated from a three-way stopcock connected to the indwelling catheter in one of the patients at a concentration of 45 cfu/mL. A similar strain was also isolated from the urine of one other patient on the same floor. The data suggest that E. aerogenes caused septicaemia via low bacterial contamination of a three-way stopcock in a peripheral drip intravenous infusion system in at least one patient, and that the outbreak of E. aerogenes infections was due to clonally-related strains.

Adult↗
PubMed2002

The role of mast cells in the development of 2, 4, 6-trinitrobenzene sulfonic acid-induced colitis in rats.

BACKGROUND: The role of mast cells in Crohn disease (CD) remains to be established. The aim of this study was to elucidate this in the development of CD-like colitis in rats by the use of mast-cell-deficient Ws/Ws and their control W+/W+ rats. METHODS: CD-like colitis was induced in both groups by an enema of 10 mg of 2,4, 6-trinitrobenzene sulfonic acid (TNBS) in 50% ethanol. Colonic damage, adhesion and colonic weight were measured at 7 and 14 days after the TNBS/ethanol enema. Rat mast cell protease-2 (RMCP-2) in the colonic tissue was also measured at 7 days after the enema. RESULTS: There was no significant difference between W+/W+ and Ws/Ws rats in terms of colonic damage, adhesion or colonic weight. The tissue content of RMCP-2 in Ws/Ws rats treated with either saline or TNBS/ethanol was only maintained at a much lower level than that in W+/W+ rats with the corresponding treatment. CONCLUSIONS: These results demonstrate that mast cells are not essential in the development of 2, 4, 6-trinitrobenzene sulfonic acid-induced colitis in rats.

Animals↗
PubMed2002

Mutagenesis by environmental pollutants and bio-monitoring of environmental mutagens.

There is serious concern about the adverse effects of environmental pollutants on human health. Various mutagens, which pollute air, water, and food, possibly induce mutations in humans, and are suspected of causing cancer. Environmental mutagens, such as polycyclic aromatic hydrocarbons (PAH) and heterocyclic amines are known to bind to nucleotides, resulting in the formation of DNA adducts. Some DNA adducts are fixed as mutations through replication of DNA. Reactive oxygen species generated by pollutants also induce the formation of DNA adducts. DNA adducts have been detected as a marker for the exposure of humans and wild life to mutagens. Because of its high sensitivity the 32P-postlabel-thin layer chromatography (TLC) method is widely used for the analysis of DNA adducts formed by PAH and related bulky compounds. However, new systems are required for detecting mutations induced in genomic DNA in vivo to monitor environmental mutagens. Recently, transgenic animals, in which a target gene for detecting mutations is integrated, have been developed. With these transgenic animals, not only mutant frequency but mutation spectra can be determined. We review here recent advances in the detection of DNA adducts formed by environmental pollutants and their application for biological monitoring of environmental mutagens. We also discuss transgenic animals as important tools for evaluating the total mutagenic potential of environmental chemicals.

Animals↗
PubMed2001

Application of quantitative ethanol detector (QED) test kit to measure ethanol concentration in blood samples.

In this paper, the applicability of the quantitative ethanol detector (QED) test kit for screening of ethanol concentrations in blood samples was investigated. The pretreatment of blood using the sulfosalicylic acid solution and the three-way stopcock followed by membrane filtration gave satisfactory results. The ethanol concentrations in whole blood samples (n=61) determined by QED correlated well with those determined by gas chromatography; the correlation coefficient indicated 0.990. Because a high correlation coefficient (0.928) was also confirmed in trial by investigators, QED test should be highly considered for ethanol screening in forensic praxis.

Benzenesulfonates↗
PubMed2001

The complete DNA sequence of the mitochondrial genome of the self-fertilizing fish Rivulus marmoratus (Cyprinodontiformes, Rivulidae) and the first description of duplication of a control region in fish.

We isolated Rivulus marmoratus mitochondrial DNA by long-polymerase chain reaction with conserved primers, and sequenced it with 36 sets of internal conserved primers, which were designed from the extensive sequence similarities of mitochondrial DNA from several fish species. The R. marmoratus mitochondrial DNA has 17,329 bp with a conserved structural organization compared to those of other fish. Rivulus marmoratus mitochondrial DNA also has two nearly identical control regions. The basic characteristics of the R. marmoratus mitochondrial genome are discussed.

Animals↗
PubMed2001

Racial differences in cellular composition of benign prostatic hyperplasia.

BACKGROUND: The present study was designed to compare the cellular composition of benign prostatic hyperplasia (BPH) in Caucasian-American (CA), African-American (AA), and Japanese (JP) men. METHODS: Biopsy specimens of the prostate were obtained from 15 men of each racial group with a prostate-specific antigen (PSA) of 4.1-10.0 ng/mL. The stained cores were quantitatively analyzed for the percentage of the area with different cellular composition (stroma (S), epithelium (E), epithelial lumen (L), and glandular component (E + L = G)), using computer-assisted color imaging. RESULTS: The mean percent area density of S, E, and L in the prostate of CA men was 84.2, 12.1, and 3.8%, respectively; for AA, 84.4, 12.4, and 3.2%; for JP, 77.4, 15.2, and 7.5%. The S/E ratio is significantly lower in JP than in CA men. The S/G ratio is significantly lower in JP than in CA and AA men. Overall, JP contained more glandular lumen and less stromal component than that of CA and AA. CA and AA showed no significant difference in cellular composition. CONCLUSIONS: The present study demonstrated the differences in cellular composition of BPH among the three races. This cellular composition divergence may account for previously observed racial differences in PSA, PSA density, and the incidence of clinical BPH.

Aged↗
PubMed2001

Receptor engagement by viral interleukin-6 encoded by Kaposi sarcoma-associated herpesvirus.

Receptor usage by viral interleukin-6 (vIL-6), a virokine encoded by Kaposi sarcoma- associated herpesvirus, is an issue of controversy. Recently, the crystal structure of vIL-6 identified vIL-6 sites II and III as directly binding to glycoprotein (gp)130, the common signal transducer for the IL-6 family of cytokines. Site I of vIL-6, however, comprising the outward helical face of vIL-6, where human IL-6 (hIL-6) would interact with the specific alpha-chain IL-6 receptor (IL-6R), is accessible and not occupied by gp130. This study examined whether this unused vIL-6 surface is available for IL-6R binding. By enzyme-linked immunosorbent assay, vIL-6 bound to soluble gp130 (sgp130) but not to soluble IL-6R (sIL-6R). Using plasmon surface resonance, vIL-6 bound to sgp130 with a dissociation constant of 2.5 microM, corresponding to 1000-fold lower affinity than that of hIL-6/sIL-6R complex for gp130. sIL-6R neither bound to vIL-6 nor affected vIL-6 binding to gp130. In bioassays, vIL-6 activity was neutralized by 4 monoclonal antibodies (mAbs) recognizing a domain within vIL-6 site I, mapped to the C-terminal part of the AB-loop and the beginning of helix B. The homologous region in hIL-6 participates in site I binding to IL-6R. In addition, binding of vIL-6 to sgp130 was interfered with specifically by the 4 neutralizing anti-vIL-6 mAbs. Based on the vIL-6 crystal structure, the vIL-6 neutralizing mAbs map outside the binding interface to gp130, suggesting that they either produce allosteric changes or block necessary conformational changes in vIL-6 preceding its binding to gp130. These results document that vIL-6 does not bind IL-6R and suggest that conformational change may be critical to vIL-6 function.

Allosteric Regulation↗