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Biomedical subjects

M Okano

Publications and source records attributed to M Okano.

At least 73 records · Page 4Linked to original sources
PubMed1999

DNA methyltransferases Dnmt3a and Dnmt3b are essential for de novo methylation and mammalian development.

The establishment of DNA methylation patterns requires de novo methylation that occurs predominantly during early development and gametogenesis in mice. Here we demonstrate that two recently identified DNA methyltransferases, Dnmt3a and Dnmt3b, are essential for de novo methylation and for mouse development. Inactivation of both genes by gene targeting blocks de novo methylation in ES cells and early embryos, but it has no effect on maintenance of imprinted methylation patterns. Dnmt3a and Dnmt3b also exhibit nonoverlapping functions in development, with Dnmt3b specifically required for methylation of centromeric minor satellite repeats. Mutations of human DNMT3B are found in ICF syndrome, a developmental defect characterized by hypomethylation of pericentromeric repeats. Our results indicate that both Dnmt3a and Dnmt3b function as de novo methyltransferases that play important roles in normal development and disease.

Animals↗
PubMed1999

Cutaneous lymphocyte antigen is expressed on memory/effector B cells in the peripheral blood and monocytoid B cells in the lymphoid tissues.

Cutaneous lymphocyte antigen (CLA) is expressed on a subpopulation of human memory T cells and is involved in the primary step of their skin homing. T cells and some B cells in the peripheral blood express CLA, but the pathophysiologic roles of CLA(+) B cells have not yet been clarified. We examined the relationships among CLA expression in B cells and immunoglobulin heavy chain subtype, the localization of CLA(+) B cells in the peripheral lymphoid tissues, and their functional binding to E-selectin. CLA was expressed on class-switched, memory B cells in the peripheral blood and tonsils as revealed by flow cytometry. Immunohistochemical staining of the lymph nodes with various types of inflammation or reactive hyperplasia showed CLA on the monocytoid B cells, which correspond to memory cells. The functional study revealed that CLA on B cells bound to E-selectin transfectants. E-selectin was detected on some of the high endothelial venules in the monocytoid B-cell-rich lymph nodes. These findings suggest that CLA is also expressed on a subset of memory/effector B cells, in addition to a subset of memory T cells. Such B cells were located in the lymph nodes or tonsils and rarely in chronic dermatitis. Therefore, CLA seems to be related to memory/effector B-cell trafficking to the lymph nodes or tonsils. According to the multistep theory, mechanisms involved in the second or third step might be different between CLA(+) B and T cells.

Antibodies, Monoclonal↗
PubMed1999

Purification, identification, and cDNA cloning of Cha o 2, the second major allergen of Japanese cypress pollen.

The second major allergen of Chamaecyparis obtusa (Japanese cypress) pollen, Cha o 2, has been purified and its cDNA cloned. Of patients with pollinosis caused by C. obtusa, 82.5% produce IgE antibodies which react with purified Cha o 2. The purified protein has a molecular mass of 46 kDa and its 12 N-terminal amino acid sequence displays a high homology with that of Cry j 2, the second major allergen of Cryptomeria japonica pollen. cDNA clones coding for Cha o 2 have been isolated using Cry j 2 cDNA as a probe. Cha o 2 cDNA clones were sequenced and found to code a putative 50-residue signal sequence and a 464-residue mature protein with a molecular weight of 50 kDa. Two possible N-linked glycosylation sites were found in the sequence. The deduced amino acid sequence of Cha o 2 shows 74.3% identity with that of Cry j 2. In its primary structure, Cha o 2 shows significant identity with those of the polygalacturonases of avocado, tomato, and maize as well as Cry j 2.

Allergens↗
PubMed1999

The type II activin receptors are essential for egg cylinder growth, gastrulation, and rostral head development in mice.

The type II activin receptors, ActRIIA and ActRIIB, have been shown to play critical roles in axial patterning and organ development in mice. To investigate whether their function is required for mesoderm formation and gastrulation as implicated in Xenopus studies, we generated mice carrying both receptor mutations by interbreeding the ActRIIA and ActRIIB knockout mutants. We found that embryos homozygous for both receptor mutations were growth arrested at the egg cylinder stage and did not form mesoderm. Further analyses revealed that ActRIIA(-/-)ActRIIB(+/-) and about 15% of the ActRIIA(-/-) embryos failed to form an elongated primitive streak, resulting in severe disruption of mesoderm formation in the embryo proper. Interestingly, we observed similar gastrulation defects in ActRIIA(-/-)nodal(+/-) double mutants, which, if they developed beyond the gastrulation stage, displayed rostral head defects and cyclopia. These results provide genetic evidence that type II activin receptors are required for egg cylinder growth, primitive streak formation, and rostral head development in mice.

Activin Receptors, Type II↗
PubMed1999

In vivo kinetics of transduced cells in peripheral T cell-directed gene therapy: role of CD8+ cells in improved immunological function in an adenosine deaminase (ADA)-SCID patient.

We previously reported successful peripheral T cell-directed gene therapy in a boy with adenosine deaminase (ADA)-SCID. In the present study, to better understand the reconstitutive effect of this gene therapy on his immunological system, we investigated the in vivo kinetics and functional subsets of T cells in PBL. Apparent immunological improvements were obtained after infusion of transduced cells at more than 4 x 108 cells/kg/therapy/3 mo. Frequency of ADAcDNA-integrated cells in PBL, ADA activity in PBL and clinical improvement showed good correlation, even though CD8+ cells gradually became predominant in PBL. On the basis that polyethylene glycol (PEG)-ADA was maintained at the same dosage as before gene therapy, we consider that his immunological improvement resulted from the gene therapy itself. Most CD3+ cells in PBL after gene therapy expressed TCRalphabeta. Analysis of TCR repertoire based on TCR V region usage revealed no expansion of limited clones in his PBL. The T cell subset cells CD8+CDw60+ and CD8+CD27+CD45RA-, which are reported to provide substantial help to B cells, were maintained throughout the gene therapy. Furthermore, his reconstituted peripheral T cells helped normal B cells to produce substantial IgG in vitro. Expression of both Th1- and Th2-type cytokine genes was induced in his reconstituted T cells at the same comparably high level as in normal subjects. Collectively, these results provide evidence of persistent and distinct functions of transduced cells in this patient's PBL after gene therapy.

Adenosine Deaminase↗
PubMed1999

Cloning, expression and chromosome locations of the human DNMT3 gene family.

DNA methylation plays an important role in animal development and gene regulation. In mammals, several genes encoding DNA cytosine methyltransferases have been identified. DNMT1 is constitutively expressed and is required for the maintenance of global methylation after DNA replication. In contrast, the murine Dnmt3 family genes appear to be developmentally regulated and behave like de novo DNA methyltransferases in vitro. In this study, we have cloned human DNMT3A and DNMT3B that encode full-length DNMT3A and DNMT3B proteins with 98% and 94% amino acid sequence identity to their murine homologues. The DNMT3A and DNMT3B show high homology in the carboxy terminal catalytic domain and contain a conserved cysteine-rich region, which shares homology with the X-linked ATRX gene of the SNF2/SWI family. We have mapped human DNMT3A and DNMT3B to chromosomes 2p23 and 20q11.2 respectively, and determined the DNMT3B genomic structure. We further show that DNMT3A expression is ubiquitous and can be readily detected in most adult tissues, whereas DNMT3B is expressed at very low levels in most tissues except testis, thyroid and bone marrow. Significantly, both DNMT3A and DNMT3B expression is elevated in several tumor cell lines to levels comparable to DNMT1. The cloning of the human DNMT3 genes will facilitate further biochemical and genetic studies of their functions in establishment of DNA methylation patterns, regulation of gene expression and tumorigenesis.

Amino Acid Sequence↗
PubMed1999

Mice lacking NK cells develop an efficient Th1 response and control cutaneous Leishmania major infection.

NK cells are believed to play a critical role in the development of immunity against Leishmania major. We recently found that transplantation of wild-type bone marrow cells into neonatal tgepsilon 26 mice, which are deficient in T and NK cells, resulted in normal T cell development, but no or poor NK cell development. Using this novel model we analyzed the role of NK cells in the development of Th1 response and control of cutaneous L. major infection. Mice selectively lacking NK cells (NK-T+) developed an efficient Th1-like response, produced significant amounts of IL-12 and IFN-gamma, and controlled cutaneous L. major infection. Administration of neutralizing IL-12 Abs to NK-T+ mice during L. major infection resulted in exacerbation of the disease. These results demonstrate that NK cells are not critical for development of protective immunity against L. major. Furthermore, they indicate that IL-12 can induce development of Th1 response independent of NK cells in NK-T+ mice following L.major infection.

Animals↗
PubMed1999

Familial paroxysmal dystonic choreoathetosis: clinical findings in a large Japanese family and genetic linkage to 2q.

BACKGROUND: Paroxysmal dystonic choreoathetosis (PDC) is a rare familial movement disorder that has been mapped to chromosome 2q31-36. OBJECTIVE: To study the first Japanese family with PDC clinically and genetically. PATIENTS AND METHODS: We studied a large Japanese family in which at least 17 members in 6 generations have been affected by PDC. We interviewed and examined 26 family members, 8 of whom revealed choreoathetosis-like and dystonialike involuntary movement and 1 of whom revealed no involuntary movement but only muscle stiffness such as the aura of paroxysmal dystonic choreoathetosis (PDC). Genetic linkage studies of this family were carried out with polymorphic DNA markers. RESULTS: The attacks of involuntary movement or muscle stiffness were precipitated by ovulation, menstruation, emotional stress, or caffeine or alcohol ingestion. Magnetic resonance imaging of the brain revealed no abnormalities. Clonazepam therapy was effective for reducing the attacks, and ingestion of garlic was believed by patients to be effective for softening the attacks. An affected woman with only muscle stiffness showed remission after hysterectomy for hysteromyoma. This woman also had the disease haplotype and transferred it to her typical PDC-affected daughter. Maximal pairwise logarithm of odds scores exceeding 2.00 were obtained at D2S2250, D2S1242, D2S377, D2S2148, and D2S126. The PDC gene was demonstrated by linkage analyses to be located in a 15.3-centimorgan interval lying between D2S371 and D2S339 based on pairwise and multipoint logarithm of odds scores and obligate recombination events in affected individuals. CONCLUSIONS: Linkage of PDC to chromosome 2q32-36 was confirmed in a Japanese family. The clinical characterizations of this family with PDC include that ovulation seems also to be a precipitating factor of the attacks and that hysterectomy seems to be effective for softening the attacks. Although low-dose clonazepam treatment was most effective, garlic use was believed by affected members to be effective for softening the attacks. Furthermore, based on the results of clinical and genetic analyses, we suggest that muscle stiffness without involuntary movement may represent a forme fruste of PDC.

Athetosis↗
PubMed1999

Analysis of exogenous dehydroepiandrosterone excretion in urine by gas chromatography/combustion/isotope ratio mass spectrometry.

A detailed procedure for the analysis of exogenous dehydroepiandrosterone (DHEA) in urine by gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS) has been established for detecting doping with DHEA. The average delta-value (parts per thousand difference of (13)C/(12)C ratio from the isotope ratio standard) of 26 synthetic steroids commercially available was -30.1 +/- 2.6, and was significantly lower than that of human endogenous DHEA in urine of the world class athletes who had participated in the XVIIth Olympic Winter Games (-20.3 +/- 2.1, n = 446). Although large inter-individual variations of urinary DHEA excretion were observed following a single oral administration of 50 mg of DHEA, no significant inter-individual difference was found when the excretion of exogenous DHEA was monitored in terms of delta-values using GC/C/IRMS; the minimum delta-values were observed around 6-8 h after the administration, and the values returned to the base level at over 72 h after the dosing. Thus, the deviations in delta-values of DHEA and its diol metabolites are considered to be conclusive evidence for detecting doping with DHEA. Some successful cases of detection of doping with DHEA from athletes are also reported.

Administration, Oral↗
PubMed1999

Identification of an autoimmune enteropathy-related 75-kilodalton antigen.

BACKGROUND & AIMS: We have previously reported a 75-kilodalton autoantigen specific to X-linked autoimmune enteropathy (AIE) associated with tubulonephropathy. The aim of this study was to identify the autoantigen. METHODS: Complementary DNA (cDNA) clones were isolated by immunoscreening a human duodenal cDNA-expression library with serum from a patient with AIE. RESULTS: cDNA encoding the 75-kilodalton antigen (AIE-75) was identified. The composite nucleotide sequence of the cDNA for AIE-75 was 2214 base pairs long and encoded 552 amino acids. The genomic sequence of AIE-75 was found in Sequence DataBank, which consisted of 21 exons and was located on the chromosome 11p14.3. Recombinant AIE-75 specifically reacted with sera from 3 of 4 unrelated patients with AIE but not with 58 control sera. AIE-75 was predominantly distributed in the epithelial cells of the luminal surface and the upper half of the crypts of the intestine and in the proximal renal tubulus. Similarity searches revealed that the AIE-75 cDNA sequence was an authentic form of several colon cancer-related cDNAs of unknown function. The deduced amino acid sequence contained 3 conserved PSD-95/Dlg/ZO-1 (PDZ) domains. CONCLUSIONS: AIE-75 is a PDZ domain-containing protein expressed in the differentiated epithelial cells of the intestine and kidney and may be involved in protein-protein interaction. The identification of the autoantigen may prove useful in the approach to the pathogenesis of this poorly understood disease.

Amino Acid Sequence↗
PubMed1999

CD80 (B7-1) and CD86 (B7-2) antigens on house dust mite-specific T cells in atopic disease function through T-T cell interactions.

BACKGROUND: CD80 (B7-1) and CD86 (B7-2) play an important role in antigen presentation to effector cells. Recent studies have demonstrated that these costimulatory molecules are also expressed on activated T cells. However, the functional role of CD80 and CD86 expressed on allergen-specific T cells in atopic diseases has not yet been clarified. OBJECTIVE: We sought to determine the functional role of CD80 and CD86 expressed on allergen-specific T cells in atopic diseases. METHODS: We assayed the expression of CD80 and CD86 on allergen-specific T-cell lines from patients with perennial allergic rhinitis stimulated by Dermatophagoides farinae-crude (Der f-c) antigen, 1 of the major allergens causing house dust mite allergy. T-cell proliferation induced by Der f-c-specific T-T cell interactions was measured, and the role of CD80 and CD86 in this proliferation was examined. In addition, we compared the proportion of CD45RO+CD86(+) T cells in primary culture of PBMCs stimulated by Der f-c antigen between patients with perennial allergic rhinitis and control subjects. RESULTS: On T-cell activation, CD86 antigen was upregulated earlier than CD80. Both CD80 and CD86 expressed on Der f-c-specific T cells could provide costimulatory signals to induce allergen-specific T-cell proliferation that was partially inhibitable by both anti-CD80 and anti-CD86 mAbs. The proportion of CD45RO+CD86(+) T cells in primary culture from atopic patients was significantly higher than that from control subjects. CONCLUSION: These results suggest that costimulatory molecules, such as CD80 and CD86, expressed on allergen-specific T cells may be involved in the amplification of allergen-specific immune responses through T-T cell interactions in atopic diseases.

Adult↗
PubMed1999

Strain-dependent induction of allergic rhinitis without adjuvant in mice.

BACKGROUND: To date, no murine models have been reported to show the induction of both antigen-specific IgE and nasal eosinophilia, two of the major hallmarks of allergic rhinitis, after local sensitization in the absence of adjuvants, a phenomenon which reflects natural exposure. In this report, we attempted to establish a murine model representing an initiation of allergic rhinitis. METHODS: BALB/c, CBA/J, and C57BL/6 mice were sensitized intranasally to Schistosoma mansoni egg antigen (SEA) solely. After repeated sensitization, serum Ab titers, nasal eosinophilia, and cytokine production by nasal lymphocytes were determined. RESULTS: BALB/c mice produced SEA-specific IgE after repeated sensitization. High-dose sensitization to SEA induced IgE production in CBA/J mice, while C57BL/6 mice did not show the production throughout the period observed, suggesting that IgE production was regulated genetically. BALB/c mice also exhibited nasal eosinophilia after the nasal challenge. In addition, nasal lymphocytes sensitized with SEA intranasally produced significant amount of IL-5 in vitro. CONCLUSIONS: These results suggest that intranasal sensitization with SEA in the absence of adjuvants induces a Th2 immune reaction, reflecting the hallmarks of the initiation of allergic rhinitis both in vivo and in vitro, which is genetically regulated.

Animals↗
PubMed1999

Prevalence and prediction of allergic rhinitis using questionnaire and nasal smear examination in schoolchildren.

Allergic rhinitis is a common condition among schoolchildren. However, little is known about the prevalence of nasal eosinophilia. We investigated the prevalence of rhinitis via questionnaire and nasal smears for eosinophils. The questionnaire was administered in 1992 and 1995. Complete responses were obtained from 1044 and 431 schoolchildren, respectively, of whom 26.5% and 22.5% claimed to have nasal symptoms. Nasal smears were taken in 1992, 1993 and 1994, and 415, 285 and 384 samples were collected, respectively. Positive eosinophilia were seen in 39.8%, 35.1% and 35.9% children in 1992, 1993 and 1994, respectively. In 1992, we utilized both questionnaire and nasal smears simultaneously to evaluate 415 schoolchildren. Of 415 schoolchildren, 72 (17.3%) had both nasal symptoms and nasal eosinophilia. Interestingly, those who showed positive eosinophilia in 1992, especially those who had eosinophilia with nasal symptoms, had significantly higher incidence of nasal symptoms three years later in 1995 than those who showed negative eosinophilia in 1992. These results suggest that nasal eosinophilia in schoolchildren are associated with subsequent nasal symptoms, and that nasal smear examination may be a potentially valuable test to predict prolonged or recurrent allergic rhinitis.

Adolescent↗
PubMed1999

Kawasaki disease and human lymphotropic virus infection.

Human lymphotropic viruses interacting with human immune systems may cause a wide spectrum of human diseases. Kawasaki disease has been thought to be related to events associated with infection, although a direct causative role has not been clearly demonstrated. In this concise review, the reported relationship between human lymphotropic viruses and Kawasaki disease is briefly described.

Adenovirus Infections, Human↗
PubMed1999

Involvement of carbohydrate on phospholipase A2, a bee-venom allergen, in in vivo antigen-specific IgE synthesis in mice.

BACKGROUND: Carbohydrates on allergens are known to be important for allergenicity. However, most findings have been made with epitope analysis. In this study, we investigated the involvement of N-glycan on phospholipase A2 (PLA2), the major allergen of honeybee venom, in in vivo synthesis of specific IgE in mice. METHODS: CBA/J and C57BL/6 mice were sensitized intranasally with either native or deglycosylated PLA2 in the absence of adjuvant. After repeated sensitization, serum Ab titers against PLA2 were determined. PLA2 was deglycosylated chemically with anhydrous trifluoromethanesulfonic acid (TFMS). RESULTS: CBA/J mice showed PLA2-specific IgE production after repeated sensitization with native PLA2. They also produced PLA2-specific IgG1 predominantly, suggesting that Th2-type Ab production was induced. When we used deglycosylated PLA2 as a competitor in ELISA for detecting PLA2-specific IgE, deglycosylated PLA2 completely inhibited the binding between native PLA2 and IgE. Deglycosylated PLA2 had the same potential for inducing specific IgE synthesis as native PLA2, since sensitization with deglycosylated PLA2 also elicited IgE production in CBA/J mice. CONCLUSIONS: These results suggest that carbohydrate on PLA2 is less important than previously thought not only as a dominant IgE epitope but also in synthesis of PLA2-specific IgE in vivo.

Allergens↗
PubMed1998

Mice with STAT6-targeted gene disruption develop a Th1 response and control cutaneous leishmaniasis.

The cutaneous growth of Leishmania mexicana was measured in STAT6-deficient mice (STAT6-/-) and compared with that in similarly infected wild-type (STAT6+/+) mice. Following s.c. inoculation with 5 x 10(6) amastigotes of L. mexicana into the shaven rump, STAT6+/+ mice developed large, nonhealing cutaneous lesions, while STAT6-/- mice failed to develop detectable lesions during most of the course of study. As infection progressed, STAT6+/+ mice infected with L. mexicana displayed significantly higher titers of Leishmania-specific IgG1 and IgE compared with STAT6-/- mice, which conversely produced significantly higher titers of Leishmania-specific IgG2a, indicating development of a Th1-like response in the latter group. At 12 wk postinfection, Leishmania Ag-stimulated lymph node cells from STAT6-/- mice produced significantly higher amounts of IL-12 and IFN-gamma than those from STAT6+/+ mice as measured by ELISA. However, there was no significant difference in IL-4 production between the two groups. Semiquantitative RT-PCR of transcript levels in intact draining lymph nodes and skin from inoculation sites confirmed a similar pattern of cytokines in vivo as that observed in stimulated lymph node cells in vitro. These results indicate that STAT6-mediated IL-4 signaling is critical for progression of L. mexicana infection in genetically susceptible mice and demonstrate that in the absence of STAT6, susceptible mice default toward a Th1-like response and control cutaneous L. mexicana infection.

Animals↗