Search PubMed⌕ Search

Biomedical subjects

M Okano

Publications and source records attributed to M Okano.

At least 91 records · Page 5Linked to original sources
PubMed1998

Dnmt2 is not required for de novo and maintenance methylation of viral DNA in embryonic stem cells.

We have shown previously that de novo methylation activities persist in mouse embryonic stem (ES) cells homozygous for a null mutation of Dnmt1 that encodes the major DNA cytosine methyltransferase. In this study, we have cloned a putative mammalian DNA methyltransferase gene, termed Dnmt2 , that is homologous to pmt1 of fission yeast. Different from pmt1 in which the catalytic Pro-Pro-Cys (PPC) motif is 'mutated' to Pro-Ser-Cys, Dnmt2 contains all the conserved methyltransferase motifs, thus likely encoding a functional cytosine methyltransferase. However, baculovirus-expressed Dnmt2 protein failed to methylate DNA in vitro . To investigate whether Dnmt2 functions as a DNA methyltransferase in vivo , we inactivated the Dnmt2 gene by targeted deletion of the putative catalytic PPC motif in ES cells. We showed that endogenous virus was fully methylated in Dnmt2 -deficient mutant ES cells. Furthermore, newly integrated retrovirus DNA was methylated de novo in infected mutant ES cells as efficiently as in wild-type cells. These results indicate that Dnmt2 is not essential for global de novo or maintenance methylation of DNA in ES cells.

Amino Acid Sequence↗
PubMed1998

Successful peripheral T-lymphocyte-directed gene transfer for a patient with severe combined immune deficiency caused by adenosine deaminase deficiency.

Ten patients with adenosine deaminase deficiency (ADA-) have been enrolled in gene therapy clinical trials since the first patient was treated in September 1990. We describe a Japanese ADA- severe combined immune deficiency (SCID) patient who has received periodic infusions of genetically modified autologous T lymphocytes transduced with the human ADA cDNA containing retroviral vector LASN. The percentage of peripheral blood lymphocytes carrying the transduced ADA gene has remained stable at 10% to 20% during the 12 months since the fourth infusion. ADA enzyme activity in the patient's circulating T cells, which was only marginally detected before gene transfer, increased to levels comparable to those of a heterozygous carrier individual and was associated with increased T-lymphocyte counts and improvement of the patient's immune function. The results obtained in this trial are in agreement with previously published observations and support the usefulness of T lymphocyte-directed gene transfer in the treatment of ADA-SCID.

Adenosine Deaminase↗
PubMed1998

Enhanced Th2-like responses in IL-1 type 1 receptor-deficient mice.

IL-1 has a number of effects on T cell growth but a specific role for IL-1 in T cell responses in vivo has not been elucidated. In this study the role of IL-1 in Th1/Th2 responses was examined in mice deficient for the IL-1 type 1 receptor (IL-1RI-/-) during cutaneous Leishmania major infection or following immunization with keyhole limpet hemocyanin (KLH). After inoculation of L. major stationary phase promastigotes into the hind footpad, both IL-1RI-/- and wild-type (WT) mice developed small lesions which resolved spontaneously. Lymph node cells from infected IL-1RI-/- mice produced significantly more IL-4 and IL-10 than those from WT mice following antigenic stimulation in vitro. Splenocytes from IL-1RI-/- and WT mice showed similar levels of antigen-induced proliferation. In contrast, splenocyte cultures from the IL-1RI-/- mice contained significantly more IL-4 than those from WT mice. Similar results were also obtained after immunization with KLH. While lymph node cells from both IL-1RI-/- and WT mice displayed similar levels of KLH-specific proliferation, those from IL-1RI-/- mice produced significantly more IL-4 than those from WT mice. Conversely, antigen-stimulated lymph node cells from WT mice secreted significantly greater amounts of IFN-gamma as compared with those from IL-1RI-/- mice. These data indicate that while IL-1 is not required for mounting an immune response or antigen-dependent proliferation, it appears to be required for normal regulation of Th1/Th2 responses and may function to negatively regulate IL-4 expression.

Animals↗
PubMed1998

Elevation of serum IgE level and peripheral eosinophil count during T lymphocyte-directed gene therapy for ADA deficiency: implication of Tc2-like cells after gene transduction procedure.

We have successfully carried out T-cell-directed gene therapy for a boy with severe combined immunodeficiency due to adenosine deaminase deficiency (ADA SCID) and unexpectedly found an elevation of serum IgE level and peripheral eosinophil count during the course. More than 90% of transduced cells cultured for 7-11 days before infusion into the patient were positive for CD8 and expressed Th2-type cytokine genes such as IL-4, IL-5 and IL-13. Furthermore, CD4(+) T-depleted PBMC (peripheral blood mononuclear cells) from the patient synthesized IgE in vitro by stimulation with IL-4. Collectively, these results suggested that Tc2-like cells in the transduced cells have distinct immunological functions to help IgE synthesis and activate eosinophils.

Adenosine Deaminase↗
PubMed1998

A 75-kD autoantigen recognized by sera from patients with X-linked autoimmune enteropathy associated with nephropathy.

Autoimmune enteropathy (AIE) is a rare disorder characterized by intractable diarrhoea and antienterocyte autoantibody. In this study, we detected a 75-kD autoantigen which distributed through the whole intestine and the kidney, as assessed by Western blot analysis using sera from two unrelated cases of AIE associated with nephropathy. Our results suggest that the detection of the autoantibody against the 75-kD antigen has a diagnostic value in AIE and that the autoimmune reaction against the 75-kD antigen may be implicated in the development of intestinal and renal tissue damage in this rare disorder.

Antigens↗
PubMed1998

Epstein-Barr virus infection and its role in the expanding spectrum of human diseases.

Recent advances of the various laboratory tests to detect Epstein-Barr virus (EBV) infection have clarified the causative role for a spectrum of EBV-associated diseases. They include lymphoproliferative disorders (LPD), which occur in immunologically compromised individuals, Hodgkin's disease (HD), chronic active EBV infection (CAEBV), virus-associated hemophagocytic syndrome (VAHS), certain forms of T cell lymphoma, and some gastric carcinomas, in addition to the classical EBV-associated diseases such as EBV genome-positive Burkitt's lymphoma (BL), undifferentiated nasopharyngeal carcinoma (NPC) and infectious mononucleosis (IM). This review intends to introduce the recent progress of studies on EBV infection mainly from the clinical points of view.

Animals↗
PubMed1998

CD86 (B7-2) antigen on B cells from atopic patients shows selective, antigen-specific upregulation.

To determine whether B7 signals are associated with atopic responses in man, we assayed CD80 and CD86 expression on B cells and monocytes from atopic patients and controls. Peripheral blood mononuclear cells from 10 patients with perennial allergic rhinitis and from 10 normal subjects were cultured in the presence or absence of house-dust-mite antigen, and B cells and monocytes were assayed for expression of CD80 and CD86 by flow cytometry. CD86 on B cells was significantly and selectively upregulated in all atopic subjects, but not in normal subjects, whereas CD80 expression was not altered in B cells from the atopic subjects or controls. In contrast, both CD80 and CD86 were upregulated in monocytes from the atopic subjects as well as the controls. However, CD86 upregulation was significantly higher in the atopic subjects than in controls. Our results seem to suggest that selective upregulation of CD86 on B cells by a challenging antigen may play a critical role in the development of Th2 cells in patients with atopic disease.

Adolescent↗
PubMed1998

Morphological changes in the orbital surface layer muscle of the rabbit eye produced by botulinum toxin.

We quantitated the morphological changes in the orbital surface layer muscles in the rabbit following the single injection of botulinum A toxin. Experiments were performed in 9 white rabbits (1.6-3.0 kg). They were administered 5 units (5 rabbits) or 10 units (4 rabbits) of botulinum toxin injected into the superior rectus muscle of one eye. The diameter of myofibers of the orbital and intermediate layer zones was measured with an ocular micrometer on histological sections 3 days and 1, 3 and 5 weeks after injection. Quantitative changes were noted in the muscle fibers of the orbital surface layer zone following the injection of 10 units of botulinum toxin. At 1 week, the diameter of myofibers in the orbital layer was reduced, but it was increased at 5 weeks compared to that in the control eyes; in contrast, no change in the diameter of muscle fibers was found in the intermediate layer zone.

Animals↗
PubMed1997

Painful small-fibre multifocal mononeuropathy and local myositis following influenza B infection.

A 47-year-old man experienced multifocal mononeuropathy and putative ganglionopathy associated with influenza B infection, characterized by aching and dysesthesia in the right arm and left leg with normal deep sense. He displayed muscle atrophy in the affected limbs, which might have resulted from local myositis or a disorder similar to neuralgic amyotrophy. Sural nerve biopsy revealed a severe loss of unmyelinated and thinly myelinated fibres, consistent with a small fibre neuropathy, without evidence of angiopathy or inflammation. We could not detect any other cause of the neuropathy except influenza B. In this case, it may be inferred that small-diameter neurons in the dorsal root ganglia and thinly- or nonmyelinated fibres were selectively involved through a post-infectious immune process. To our knowledge, small fibre neuropathy following influenza B has never been reported.

Humans↗
PubMed1997

Quassinoids as inhibitors of Epstein-Barr virus early antigen activation.

Short-term in vitro assays for tumor promoters and antitumor promoters (Epstein-Barr virus activation test) were carried out for 14 quassinoids isolated from Ailanthus altissima. Some quassinoids, including ailantinol B, ailantinol C, ailanthone, and shinjulactone A, showed moderate activity at a molar ratio of 1:100 (TPA/quassinoids), and the results led to the elucidation of structure-activity relationships.

Antigens, Viral↗
PubMed1997

Correlation of expression levels of P-glycoprotein with resistance to adriamycin in a renal adenocarcinoma cell line.

We have demonstrated that low-level expression of P-glycoprotein (PGP), detectable by reverse transcriptase polymerase chain reaction (RT-PCR) assay and flow cytometric assay, is an important factor in multidrug resistance (MDR) in ACHN cancer cells. In this study, we established a subline highly resistant to adriamycin (ACHN/ADM) from ACHN cells, and determined the correlation between PGP levels and MDR levels using ACHN/ADM cells and their parent ACHN cells. The ACHN/ADM cells showed overexpression of PGP, and sensitivity to antitumor agents was lower than that found in ACHN cells. Intracellular accumulation of ADM in ACHN/ADM cells was approximately half the amount of its accumulation in ACHN cells. Sensitivity to ADM in ACHN/ADM cells was enhanced by chemosensitizers with an increase in intracellular ADM accumulation. These results indicate that PGP levels correlate with MDR levels and suggest that chemotherapy using chemosensitizers might be effective in the treatment of renal cancers with overexpression of PGP.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed1997

Atypical MRI features of Wilson's disease: high signal in globus pallidus on T1-weighted images.

Most reports of MRI in Wilson's disease have been of abnormal low-signal lesions on T1-weighted images and high signal intensity on T2-weighted images. In contrast, we report three patients who had high-signal lesions in the globus pallidus on T1-weighted images, a finding seen in patients with portal-systemic encephalopathy. The possible causes include the paramagnetic effect of copper or iron and accumulation of Alzheimer type II glial cells.

Adult↗
PubMed1997

High susceptibility of an Epstein-Barr virus-converted Burkitt's lymphoma cell line to cytotoxic drugs.

Susceptibility to cytotoxic drugs was studied using an Epstein-Barr virus (EBV) genome-negative Burkitt's lymphoma (BL) cell line (Ramos) originating from the tumor cells and an in vitro EBV-converted Ramos cell line (B7). Decreased doubling time (DT) with increased saturation density (SD) and elevated [3H]thymidine incorporation were shown in B7, indicating more rapid cell proliferation and growth. However, B7 was highly susceptible to cytotoxic drugs when compared to Ramos. These results indicated whether the presence or absence of EBV genome in tumor cells may be beneficial for evaluation of susceptibility to cytotoxic chemotherapy in patients with BL.

Antineoplastic Agents↗
PubMed1997

Differentiation-dependent expression of laminin-8 (alpha 4 beta 1 gamma 1) mRNAs in mouse 3T3-L1 adipocytes.

We report that laminin-8 (alpha 4 beta 1 gamma 1) is the specific isoform of laminin synthesized in adipocytes. Reverse transcription-polymerase chain reaction (RT-PCR) of mRNA from mouse 3T3-L1 cells with paired primers for alpha 1, alpha 2, alpha 3, alpha 4, alpha 5, beta 1, beta 2, beta 3, gamma 1 and gamma 2 laminins yielded amplified fragments only for alpha 4, beta 1 and gamma 1. A polyclonal antibody against mouse laminin-1 (alpha 1 beta 1 gamma 1) precipitated alpha 4 in addition to beta 1 and gamma 1, while the antibody against a deduced peptide sequence of mouse alpha 4 in addition to beta 1 and gamma 1 in addition to alpha 4. Thus, laminin-8 (alpha 4 beta 1 gamma 1) is the only isoform expressed in 3T3-L1 cells. Northern blots showed that the levels of alpha 4, beta 1 and gamma 1 mRNAs increased 2.5-fold during adipose conversion of 3T3-L1 cells. A 1062 bp cDNA fragment cloned by RT-PCR demonstrated a polymorphism in the mouse alpha 4 gene which would lead to five amino acid changes in the domain G.

3T3 Cells↗
PubMed1997

Synthesis of cytotoxic fluorinated quassinoids.

The C-15 senecioyl side chain of brusatol was interchanged with fluorinated acyl groups, and the C-3 hydroxy group of bruceolide was esterified with fluorinated acyl chlorides. These fluorinated quassinoids 11, 12, 13, and 17 showed significant cytotoxic activity against eight human cancer cell lines including small and non-small cell lung, colon, CNS, ovarian and renal cancers, leukemia, and melanoma with 17 being about 100 times more potent than 11, 12, and 13. The activity of 17 was similar to that of bruceantin (1) in this in vitro cell line panel.

Acylation↗