Biomedical subjects

Takao Ando

Publications and source records attributed to Takao Ando.

23 records · Page 2Linked to original sources

PubMed2002

A novel murine model of Graves' hyperthyroidism with intramuscular injection of adenovirus expressing the thyrotropin receptor.

In this work we report a novel method to efficiently induce a murine model of Graves' hyperthyroidism. Inbred mice of different strains were immunized by i.m. injection with adenovirus expressing thyrotropin receptor (TSHR) or beta-galactosidase (1 x 10(11) particles/mouse, three times at 3-wk intervals) and followed up to 8 wk after the third immunization. Fifty-five percent of female and 33% of male BALB/c (H-2(d)) and 25% of female C57BL/6 (H-2(b)) mice developed Graves'-like hyperthyroidism with elevated serum thyroxine (T(4)) levels and positive anti-TSHR autoantibodies with thyroid-stimulating Ig (TSI) and TSH-binding inhibiting Ig (TBII) activities. In contrast, none of female CBA/J (H-2(k)), DBA/1J (H-2(q)), or SJL/J (H-2(s)) mice developed Graves' hyperthyroidism or anti-TSHR autoantibodies except SJL/J, which showed strong TBII activities. There was a significant positive correlation between TSI values and T(4) levels, but the correlations between T(4) and TBII and between TSI and TBII were very weak. TSI activities in sera from hyperthyroid mice measured with some chimeric TSH/lutropin receptors suggested that their epitope(s) on TSHR appeared similar to those in patients with Graves' disease. The thyroid glands from hyperthyroid mice displayed diffuse enlargement with hypertrophy and hypercellularity of follicular epithelia with occasional protrusion into the follicular lumen, characteristics of Graves' hyperthyroidism. Decreased amounts of colloid were also observed. However, there was no inflammatory cell infiltration. Furthermore, extraocular muscles from hyperthyroid mice were normal. Thus, the highly efficient means that we now report to induce Graves' hyperthyroidism in mice will be very useful for studying the pathogenesis of autoimmunity in Graves' disease.

Adenoviridae↗

PubMed2002

Determination of molecular mass of acidic polysaccharides by capillary electrophoresis.

We developed a method for the determination of molecular mass of acidic polysaccharides based on their high-resolution separation by capillary electrophoresis. Polymers of N-acetylneuraminic acid (NeuAc) and polysulfated hyaluronic acid were separated into their molecular species up to 100 mono- and 20 disaccharide units, respectively. The relationship between the molecular mass of NeuAc-polymer and their electrophoretic mobilities showed good linearity, and was applied to the determination of molecular masses of larger NeuAc species unresolved by capillary electrophoresis under the same conditions. In the first step, the standard curve for the determination of molecular mass was constructed from the relationship between electrophoretic mobility and molecular mass. Subsequently, the mobility was extrapolated to the standard curve, and the molecular mass was calculated. Five different preparations of NeuAc polymers having different molecular masses showed smaller values than those determined by conventional chromatographic techniques. Further, molecular mass determined by the present method correlated with number-average molecular mass. The methodology presented here was applied to the determination of molecular mass of polysulfated hyaluronic acid. The data indicated that native hyaluronic acid was extensively degraded during sulfonation reaction.

Acids↗

PubMed2002

A monoclonal thyroid-stimulating antibody.

The thyrotropin receptor, also known as the thyroid-stimulating hormone receptor (TSHR), is the primary antigen of Graves disease. Stimulating TSHR antibodies are the cause of thyroid overstimulation and were originally called long-acting thyroid stimulators due to their prolonged action. Here we report the successful cloning and characterization of a monoclonal antibody (MS-1) with TSHR-stimulating activity. The thyroid-stimulating activity of MS-1 was evident at IgG concentrations as low as 20 ng/ml. MS-1 also competed for radiolabeled TSH binding to the native TSHR and was able to compete for TSH-induced stimulation. MS-1 recognized a conformational epitope within the TSHR alpha (or A) subunit but excluding the receptor cleavage region. Using an assay measuring loss of antibody recognition after cleavage we demonstrated that MS-1, in contrast to TSH, was unable to enhance TSHR posttranslational cleavage. Since receptor cleavage is followed by alpha subunit shedding and receptor degradation, the functional half-life of the receptor may be extended. The isolation and characterization of MS-1 provides a novel explanation for the prolonged thyroid stimulation in this disease which may be secondary to the lack of receptor cleavage in addition to the prolonged half-life of IgG itself.

Animals↗

PubMed2002

Intrathyroidal fetal microchimerism in Graves' disease.

During pregnancy, fetal cells are known to reach the maternal circulation and infiltrate a variety of tissues (fetal microchimerism). Although the presence of such cells has the potential to modulate the maternal immune response to both self antigens and fetal alloantigens, the degree of their influence remains unclear. The hyperthyroidism of Graves' disease frequently abates during pregnancy and exacerbates after childbearing. Thus, we have hypothesized that fetal cells in the maternal circulation and tissues may influence this decrescendo to crescendo pattern of autoimmune thyroid disease. Part of this hypothesis was tested using an ELISA-PCR for the detection of DNA for a male-specific gene, sex-determining region Y. The sensitivity of this assay was the equivalent of approximately 1 male cell among 10(5) female cells. We initially examined paraffin-embedded thyroid tissues and detected male cells in 4 of 20 female Graves' thyroid specimens, but not in 6 of 6 female adenoma specimens. Using frozen thyroid tissue specimens, an additional 6 of 7 Graves' disease samples demonstrated intrathyroidal fetal microchimerism, whereas 1 of 4 female samples with thyroid nodules showed male cells. The greater detection of the sex-determining region Y gene in frozen female thyroid tissues was probably due to DNA fragmentation in the paraffin-derived samples. In summary, we demonstrated that intrathyroidal fetal microchimerism was common and profound in female patients with Graves' disease. Thus, fetal male cells are valid candidates for modulating autoimmune thyroid disease in pregnancy and postpartum.

Adenoma↗

PubMedDate not supplied

The effects of alpha interferon on the development of autoimmune thyroiditis in the NOD H2h4 mouse.

Alpha interferon (alphaIFN) therapy is known to induce thyroid autoimmunity in up to 40% of patients. The mechanism is unknown, but Th1 switching has been hypothesized. The aim of our study was to examine whether alphaIFN accelerated the development of thyroiditis in genetically susceptible mice. We took advantage of NOD-H2h4, a genetically susceptible animal model, which develops thyroiditis when fed a high iodine diet. Six to eight week old male NOD H2h4 mice were injected with mouse alphaIFN (200 units) or with saline three times a week for 8 weeks. All mice drank iodinated water (0.15%). Mice were sacrificed after 8 weeks of injection. Their thyroids were examined for histology and blood was tested for antithyroglobulin antibody levels. T4 and glucose levels were also assessed. In the IFN-injected group, 6/13 (46.2%) developed thyroiditis and/or thyroid antibodies while in the saline-injected group, only 4/13 (30.8%) developed thyroiditis and/or thyroid antibodies (p = 0.4). The grade of thyroiditis was not different amongst the two groups. None of the mice developed clinical thyroiditis or diabetes mellitus. Our results showed that alphaIFN treatment did not accelerate thyroiditis in this mouse model. This may imply that alphaIFN induces thyroiditis in a non-genetically dependent manner, and this would not be detected in a genetically susceptible mouse model if the effect were small. Alternatively, it is possible that alphaIFN did not induce thyroiditis in mice because, unlike in humans, in mice alphaIFN does not induce Th1 switching.

Animals↗