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Hirokazu Kimura

Publications and source records attributed to Hirokazu Kimura.

At least 19 recordsLinked to original sources
PubMed2026

Prevalence and chronology of colibactin-associated mutational processes and their microbiome spectra in Japanese colorectal cancer.

The incidence of colorectal cancer (CRC) has risen in recent decades, with a disproportionate increase observed among younger individuals in Japan and other countries. The etiological contribution of the gut microbiota to CRC pathogenesis is recognized, yet the mechanisms involved remain to be fully clarified. Here we integrated whole-genome sequencing (WGS) and transcriptome profiling of CRC with whole-genome metagenomic sequencing of fecal samples to interrogate host-microbiome interactions at high resolution. Application of interpretable artificial intelligence enabled the stratification of CRC into four distinct microbiome-informed subtypes. WGS analysis identified mutational signatures SBS88 and ID18, linked to colibactin exposure, as early clonal events detected in 44.8% of non-hypermutated patients. Notably, these signatures were significantly more frequent among patients born after the 1960s. Microbiome-based subclassification revealed subtype-specific clinical and molecular features. Collectively, our findings indicate that colibactin exposure constitutes a prevalent and potentially modifiable risk factor for CRC in the Japanese population.

Humans↗
PubMed2025

KRAS Mutations in Duodenal Lavage Fluid After Secretin Stimulation for Detection of Pancreatic Cancer.

OBJECTIVE: Although pancreatic ductal adenocarcinoma (PDAC) is still a devastating disease, the survival rate for surgically removed PDACs has significantly improved in recent years. Early detection is essential in managing PDAC. BACKGROUND: The presence of KRAS mutations in PDAC leads to the initial genetic abnormality and offers a significant timeframe for identifying resectable PDACs. A minimally invasive and highly specific PDAC screening test is necessary to prevent the need for invasive follow-up tests. METHODS: Between July 2021 and March 2023, 169 cases were enrolled in 7 institutions. By administering secretin before esophagogastroduodenoscopy (EGD), the excretion of pancreatic juice into the papillary fluid can be stimulated, creating a resource for testing. Washing fluid was collected using a specialized catheter from control individuals (n=75) and patients with resectable PDAC (n=89) at the initial diagnosis. A highly sensitive technique was employed to study KRAS gene mutations. RESULTS: This study obtained an AUC of 0.934 (95% CI: 0.904, 0.964) when using KRAS mutations in duodenal lavage fluid to differentiate between patients with resectable PDAC and healthy controls. The estimated sensitivities were calculated with specificity set at 100%, resulting in a sensitivity of 83.1% (95% CI: 71.7%, 91.2%). The McNemer test showed a significantly higher sensitivity for KRAS mutations than serum CEA and CA19-9 ( P <0.0001). CONCLUSIONS: We created a method to identify resectable PDACs by analyzing KRAS mutation levels in duodenal fluid collected during EGD with secretin stimulation of pancreatic juice secretion.

Humans↗
PubMed2006

A sensitive and reliable quantification method for mouse interleukin-12 p70 based on fluorometric sandwich ELISA (FS-ELISA).

Interleukin-12 (IL-12) p70 is an important cytokine secreted by antigen-presenting cells in response to antigenic stimulation; it is a heterodimer of p35 and p40 subunits. Here, we report a new, highly sensitive, and reliable method that employs fluorometric sandwich ELISA for quantification of the mouse IL-12 (moIL-12) p70 protein. Our method could quantify moIL-12 p70 in the range of approximately 0.5 to 500 pg/ml. In the assay, no signals were produced by the moIL-12 p40 monomer, homodimer [(p40)2], or mouse IL-23 even up to a concentration of 500 pg/ml; this ensures that our assay has a high specificity for moIL-12 p70. To demonstrate that our method can determine natural moIL-12 in real physiological/pathological samples, we monitored the moIL-12 p70 secretion from peritoneal exudative cells after lipopolysaccharide (LPS) stimulation. IL-12 p70 secretion as early as 3h after LPS stimulation was reliably detected due to the high sensitivity of the method.

Animals↗
PubMed2006

Pro-inflammatory cytokinemia is frequently found in Down syndrome patients with hematological disorders.

Down syndrome (DS) patients are frequently complicated with infections, autoimmune phenomena and hematological disorders, including transient abnormal myelopoiesis (TAM) in infancy and acute megakaryoblastic leukaemia (AMKL) in later life. In this study, serum levels of cytokines from 23 TAM and 15 AMKL patients were examined using the highly sensitive microsphere fluorescence system. Statistical differences between DS neonates with or without TAM were found in IL-1beta [median 7.0 pg/ml (0.34-271.6) verses 0.05 pg/ml (0.0-2.4), p=0.034], TNF-alpha [8.11 pg/ml (0.1-253.0) verses 0.41 pg/ml (0.1-1.5), p=0.041], and IFN-gamma [20.0 pg/ml (0.14-406.3) verses 1.5 pg/ml (0.14-5.79), p=0.036]. Moreover, abnormal inflammatory cytokinemia was also found in myelodysplastic syndrome (MDS) and AMKL with DS. These abnormal cytokinemia may have a role in the pathophysiology of TAM, MDS and AMKL in DS, especially in liver fibrosis or myelofibrosis.

Child, Preschool↗
PubMed2006

Substance use and sexual behaviours of Japanese men who have sex with men: a nationwide internet survey conducted in Japan.

BACKGROUND: Japanese men who have sex with men (MSM), especially those living in large metropolitan areas such as Tokyo and Osaka, are facing a growing HIV/AIDS epidemic. Although the Internet is used as a new venue for meeting sex partners, it can also serve as a useful research tool for investigating the risk behaviours of Japanese MSM. This Internet survey explored the extent of substance use and its association with sexual risk behaviours among Japanese MSM. METHODS: Between 28 February 2003 and 16 May 2003 MSM were recruited through 57 Japanese gay-oriented Web sites, gay magazines, and Internet mailing lists. Participants completed a structured questionnaire anonymously through the Internet. RESULTS: In total, 2,062 Japanese MSM completed the questionnaire. The average age of participants was 29.0 years and 70.5% identified as gay, 20.8% as bisexual, and 8.7% as other. Overall, 34.5% reported never using a substance, 45% reported ever using one type of substance (lifetime reported single substance users), and 19.6% had used more than 1 type of substance (lifetime reported multiple substance users) in their lifetimes. The substances most commonly used were amyl nitrite (63.2%), 5-methoxy-N, N-diisopropyltryptamine (5MEO-DIPT) (9.3%), and marijuana (5.7%). In the multivariate analysis, unprotected anal intercourse, having had 6 or more sexual partners, visiting a sex club/gay venue in the previous 6 months, a lower education level, and being 30 to 39 years of age were associated with both lifetime single and lifetime multiple substance use. Lifetime reported multiple substance use was also correlated with having a casual sex partner, having symptoms of depression, being diagnosed as HIV-positive, and greater HIV/AIDS-related knowledge. CONCLUSION: This is the first Internet-based research focused on the sexual and substance use behaviours of MSM in Asia. Our findings suggest a compelling need for prevention interventions to reduce HIV risk-related substance use behaviours among Japanese MSM. The results also suggest that the Internet is potentially a useful tool for collecting behavioural data and promoting prevention interventions among this population.

5-Methoxytryptamine↗
PubMed2006

Lysophosphatidylethanolamine in Grifola frondosa as a neurotrophic activator via activation of MAPK.

We found that Grifola frondosa extracts induced the activation of mitogen-activated protein kinase (MAPK) in cultured PC12 cells, a line of rat pheochromocytoma cells. The active substance was isolated by a few chromatographic steps, including high-performance liquid chromatography, and was identified to be lysophosphatidylethanolamine (LPE) from various structural analyses. LPE from G. frondosa (GLPE) was confirmed to induce the activation of MAPK of cultured PC12 cells and was found to suppress cell condensation and DNA ladder generation evoked by serum deprivation, suggesting that the GLPE had antiapoptotic effects. Moreover, GLPE caused morphological changes in and upregulation of neurofilament M expression of PC12 cells, demonstrating that the GLPE could induce neuronal differentiation of these cells. The activation of MAPK by GLPE was suppressed by AG1478, an antagonist of epidermal growth factor receptor (EGFR), and by U0126, an inhibitor of MAPK kinase (MEK1/2), but not by K252a, an inhibitor of TrkA, or by pertussis toxin. These results demonstrate that GLPE induced the MAPK cascade [EGFR-MEK1/2-extracellular signal-regulated protein kinases (ERK1/2)] of PC12 cells, the activation of which induced neuronal differentiation and suppressed serum deprivation-induced apoptosis. This study has clarified for the first time the involvement of the MAPK signal cascade in LPE actions.

Animals↗
PubMed2006

Phylogenetic analysis of envelope glycoprotein (E1) gene of rubella viruses prevalent in Japan in 2004.

We performed a molecular epidemiological study on the envelope glycoprotein gene (E1 gene) obtained by PCR amplification from specimens of 17 rubella patients in certain areas (Gunma, Saitama, and Kagoshima prefectures, and Tokyo metropolitan area) in Japan in 2004. In these sequences of partially amplified DNAs (283 bases) within the E1 gene, no nucleotide substitution was observed. They were classified into genotype 1D of clade 1 in the constructed phylogenetic tree. One amino acid substitution was found between the amino acid sequence predicted from these DNAs and those of Japanese strains [To-336 vaccine strain (To-336 vac) and its wild progenitor (To-336 wt)]. The results suggest that the rubella viruses (RV) prevalent in certain areas of Japan in 2004 were highly homologous and were closely related with Japanese vaccine strain.

Adolescent↗
PubMed2006

Bis-(2-amino-5-selenazoyl) ketone as a superoxide anion-scavenger.

We investigated the superoxide anion scavenging effects of 2-amino-1,3- selenazoles and bis-(2-amino-5-selenazoyl) ketones using a highly sensitive quantitative chemiluminescence method. At 166 microM, the 2-amino-1,3-selenazoles and bis-(2-amino-5-selenazoyl) ketones scavenged in the range of 10.0 to 80.0% of O(2)(-). Bis[2-dimethylamino-5-(1,3-selenazolyl)] ketone exhibited the strongest superoxide anion-scavenging activity among the six kinds of 2-amino-1,3-selenazoles and three kinds of bis-(2-amino-5-selenazoyl) ketones. The 50% inhibitory concentration (IC(50)) of bis[2-dimethylamino-5-(1,3-selenazolyl)] ketone was determined to be 37.1 microM. Thus, bis[2-dimethylamino-5-(1,3-selenazolyl)] ketone acted in vitro as effective and potentially useful O(2)(-) scavenger.

Free Radical Scavengers↗
PubMed2006

Omenn syndrome--review of several phenotypes of Omenn syndrome and RAG1/RAG2 mutations in Japan.

Omenn syndrome (OS) is a form of severe combined immunodeficiency (SCID) characterized by erythrodermia, hepatosplenomegaly, lymphadenopathy, and alopecia. In patients with OS, B cells are mostly absent, T-cell counts are normal to elevated, and T cells are frequently activated and express a restricted T-cell receptor (TCR) repertoire. Thus far, inherited hypomorphic mutations of the recombination activating genes either 1 or 2 (RAG1/2) have been detected in most OS patients. We have recently experienced a rare case of OS showing the revertant mosaicism due to multiple second-site mutations leading to typical OS clinical features with RAG1-deficient SCID. In this review, we will focus on the variation of several phenotypes of OS.

DNA-Binding Proteins↗
PubMed2006

Role of protein kinase C in eosinophil function.

Protein kinase C (PKC) isoforms are being elucidated as an increasingly diverse family of enzymes involved in the downstream signal transduction and cell function in various types of cells. To date, 11 PKC isoforms have been identified; they are grouped according to their molecular structure and mode of activation: conventional PKCs (alpha, beta I, beta II, and gamma), novel PKCs (delta, epsilon, mu, theta, and eta), and atypical PKCs (zeta, and iota/lambda). Eosinophils are involved in the pathogenesis of allergic diseases such as bronchial asthma, pollinosis, and atopic dermatitis as well as in the inflammatory response to parasitic infections. Recent studies using selective activators and inhibitors of individual PKC isoforms have revealed that this enzyme is involved in eosinophil dynamics such as cell motility and other functions. However, the role of PKCs in eosinophil functions has been not wholly understood. In this review, we have focused upon and summarized the current knowledge regarding the role of PKC isoforms in eosinophil functions.

Animals↗
PubMed2005

Elevation of cytokine concentrations in asphyxiated neonates.

BACKGROUND: Various cytokines are reportedly associated with many neonatal diseases. Asphyxia is considered to result in ischemia-reperfusion injuries and induces abnormal inflammatory responses involving excessive cytokine production. OBJECTIVES: To evaluate alteration in sera levels of various cytokines/chemokines in case of perinatal asphyxia at birth. METHODS: In order to determine the concentrations of various cytokines/chemokines in sera, we used a highly sensitive fluorescence microsphere method. We measured the concentration of 8 types of cytokines/chemokines in sera obtained from 17 cases of asphyxia, 10 normal neonates, and 6 healthy adults. RESULTS: The concentrations of IL-6, IL-8, and IL-10 in the sera of asphyxiated neonates were higher than those in the normal neonates. Irrespective of the presence or absence of asphyxia, sera concentrations of IL-2, IL-4, IFN-gamma, and TNF-alpha were higher in the neonates than those in the adults. The concentration of IFN-gamma in the asphyxiated neonates was lower than that in the normal neonates. Sera levels of IL-10 were higher in the asphyxiated cases than those in the normal neonates. The sera levels of IL-6, IL-8, and IL-10 in asphyxiated neonates with either a poor outcome or death were higher than those without poor outcomes. CONCLUSIONS: The concentrations of various types of cytokines/chemokines were different in neonatal sera and some of them increased drastically during asphyxia. The concentration of an anti-inflammatory cytokine IL-10 was elevated in asphyxiated neonates immediately after birth, thereby suggesting that IL-10 might be associated with neuroprotective functions.

Asphyxia Neonatorum↗
PubMed2005

Detection and sequence analysis of DNA polymerase and major envelope protein genes in koi herpesviruses derived from Cyprinus carpio in Gunma prefecture, Japan.

Koi herpesvirus (KHV), which is believed to be an emerging virus, causes fatal diseases in carps. Since the 1990s, the presence of KHV has been confirmed in several countries. In Japan, from 2003 to 2004, large outbreaks of KHV infection in farmed carps resulted in the death of numerous fishes. From April to May 2004, we collected 43 dead or dying carps exhibiting typical symptoms of KHV infection in Gunma prefecture. To conduct a molecular epidemiologic study of KHV in our prefecture, we amplified DNA polymerase and the major envelope protein genes of KHV derived from carp gills using newly designed primers. We also performed sequence analysis of both genes of KHV. Sensitivity of our PCR method for amplification of DNA polymerase and the major envelope protein genes of KHV was 3 x 10(2) (100 fg) and 3 x 10(3) (1000 fg) copies of KHV genome, respectively. We detected both DNA polymerase and major envelope protein genes in 37 of 43 carps (86%). No mutation was found in both the genes sequenced from 11 strains, which included two foreign strains and one domestic strain. The results suggested that KHV strains derived from carps in our prefecture were closely related genetically to the other KHV strains.

Animals↗
PubMed2005

Differential role of an atypical protein kinase C, PKC zeta, in regulation of human eosinophil and neutrophil functions.

BACKGROUND: Protein kinase C (PKC) comprises a family of isoenzymes playing a key role in downstream signaling and cell functions. PKCs are grouped according to molecular structure and mode of activation: 'conventional' PKCs (alpha, betaI, betaII, gamma), 'novel' PKCs (delta, epsilon, mu, theta, eta), and 'atypical' PKCs (zeta, tau/lambda). Here we compared the influence of PKC zeta on the function of human eosinophils and neutrophils. METHODS: After pretreating the cells with a myristoylated specific PKC zeta inhibitor, a myristoylated PKC eta inhibitor, or bisindolylmaleimide I (Bis I; an inhibitor of conventional and novel PKCs), we examined N-formyl-methionyl-leucyl-phenylalanine (FMLP)- or 4-phorbol 12-myristate 13-acetate (PMA)-evoked superoxide anion (O(2)(-)) generation. Induced PKC translocation was characterized using confocal laser scanning microscopy. RESULTS: The PKC zeta inhibitor significantly blocked FMLP- or PMA-induced O(2)(-) generation by eosinophils. However, this inhibitor attenuated PMA- but not FMLP-induced O(2)(-) generation by neutrophils. In contrast, Bis I inhibited FMLP-induced O(2)(-) generation by eosinophils and neutrophils in a similar manner. The PKC eta inhibitor had no significant effect, since both cell types lack PKC eta; this confirmed specificity of PKC zeta inhibitor effects. Finally, the translocation of PKC zeta to the plasma membrane induced by FMLP in both eosinophils and neutrophils was started at 1 min while the translocation was maintained for 15 min in eosinophils but not in neutrophils. CONCLUSION: An atypical PKC, PKC zeta, regulates human eosinophil and neutrophil functions in a differential manner.

Cell Movement↗
PubMed2005

Oligoclonal expansion of T lymphocytes with multiple second-site mutations leads to Omenn syndrome in a patient with RAG1-deficient severe combined immunodeficiency.

Omenn syndrome (OS) is a rare primary immunodeficiency characterized by the presence of activated/oligoclonal T cells, eosinophilia, and the absence of circulating B cells. OS patients carry leaky mutations of recombination activating genes (RAG1 or RAG2) resulting in partial V(D)J recombination activity, whereas null mutations cause severe combined immunodeficiency with absence of mature T and B cells (T-B- SCID). Here we describe somatic mosaicism due to multiple second-site mutations in a patient with RAG1 deficiency. We found that he is homozygous for a single base deletion in the RAG1 gene, which results in frameshift and likely abrogates the protein function. However, the patient showed typical OS features. Molecular analysis revealed that several second-site mutations, all of which restored the RAG1 reading frame and resulted in missense mutations, were demonstrated in his T cells. These findings suggest that his revertant T-cell mosaicism is responsible for OS phenotype switched from T-B- SCID.

Cell Proliferation↗
PubMed2005

Selenoureas and thioureas are effective superoxide radical scavengers in vitro.

Oxygen radicals, such as superoxide radicals, embellishing DNA, protein, lipids, etc., and carrying out the obstacle of the function of a cell is known. It depends for the oxidant level in the living body on the balance of a generation system and an elimination system of oxygen radicals, and research which controls an oxidant level in the living body is briskly done by taking in the substance which eliminates an oxygen radical. We investigated scavenging effects of superoxide radicals by selenoureas and thioureas using a highly sensitive and quantitative chemiluminescence method. At 330 nM, five selenoureas and five thioureas scavenged fractions of superoxide radicals (O2-) ranging from 8.4% to 87.6%. Among five N,N-unsubstituted selenoureas and N,N-unsubstituted thioureas 1-selenocarbamoylpiperidine and 1-thiocarbamoylpyrrolidine were the most effective scavengers. A possibility that selenoureas could use it as a new superoxide anion-scavenging substance from the result of this research became clear.

Dose-Response Relationship, Drug↗
PubMed2005

Selenocarbamates are effective superoxide anion scavengers in vitro.

We investigated the superoxide anion-scavenging effects of six selenocarbamates and four thiocarbamates, using a highly sensitive quantitative chemiluminescence method. At 333 nM, six selenocarbamates and four thiocarbamates scavenged in the range of 2.9-68.7% of O(2)*-. Se-methyl N-phenylselenocarbamate and Se-methyl N-(4-methylphenyl)selenocarbamate exhibited the strongest superoxide anion-scavenging activity among the Se-selenocarbamates. In contrast, the corresponding S-thiocarbamates had moderate inhibitory effect. The 50% inhibitory concentrations (IC(50)) of Se-methyl-N-phenylselenocarbamate and Se-methyl-N-(4-methylphenyl)selenocarbamate were determined to be 140 nM and 162 nM, respectively. Thus, these compounds acted in vitro as effective and potentially useful O(2)*- scavengers.

Carbamates↗
PubMed2005

An atypical protein kinase C, PKC zeta, regulates human eosinophil effector functions.

Protein kinase (PK) C comprises a family of isoenzymes that play key roles in downstream signalling and cell functions. We studied PKC zeta participation in the effector functions of human eosinophils stimulated with platelet-activating factor (PAF) or complement (C) 5a. After pretreating eosinophils with a myristoylated specific PKC zeta inhibitor; bisindlolylmaleimide I (BisI), an inhibitor of conventional and novel PKCs; or rottlerin, a PKC delta inhibitor, we examined PAF- and C5a-evoked functions. Induced PKC translocation was characterized by confocal laser scanning microscopy. The PKC zeta inhibitor blocked PAF- or C5a-induced eosinophil superoxide anion generation as effectively as BisI or rottlerin. The PKC zeta inhibitor also attenuated PAF- or C5a-induced eosinophil degranulation and adhesion. In contrast, the PKC zeta inhibitor did not affect PAF- or C5a-induced CD11b expression. Finally, both eosinophil shape changes and the translocation of PKC zeta and p47phox, a component of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase, to the plasma membrane induced by PAF or C5a were completely inhibited by the PKC inhibitor. Thus, the atypical PKC zeta regulates human eosinophil adhesion and effector functions.

CD11b Antigen↗