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  • 1
    ISSN: 1432-5233
    Schlagwort(e): Embryogenesis ; Glucose transporter ; Growth retardation ; Hypoglycemia ; Neural tube defect ; Rat embryo culture
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract We investigated the glucose transporter gene and protein expression during early organogenesis in the rat and in rat embryos cultured with hypoglycemic serum. Erythrocyte-type glucose transporter (GLUT-1) mRNA was expressed at a high level in embryos; peak levels were reached at days 10.5–11.5 and decreased as gestational age increased. In contrast, the insulin regulaable glucose transporter (GLUT-4) mRNA was not detected. The levels of GLUT-1 protein determined by Western blot analysis increased in parallel with expression of the glucose transporter (GLUT-1) gene and peak levels were observed on days 10.5 and 11.5, which correspond to the main periods of neural tube formation. Immunohistochemical staining of the embryo on day 10.5 showed that GLUT-1 protein was abundantly located in the tissue of neural tube. When embryos were cultured from day 9.5 to day 10.5 with insulin-induced hypoglycemic serum containing 2–3 mM glucose an increased frequency of anterior neural tube defects was observed in association with a significant reduction of the glycolytic flux. Increased levels of GLUT-1 mRNA and protein were not observed during the culture with hypoglycemic serum compared with the levels in embryos cultured in normal serum. Addition of insulin to normal serum (500 μU/ml) did not affect the GLUT-1 mRNA and protein levels. GLUT-1 mRNA and protein are strongly expressed in the embryo during early organogenesis, especially in the tissues of the neural tube, and the expression of the glucose transporter did not increase in response to prolonged glycopenia. This may account for the vulnerability of embryogenesis to hypoglycemia during these critical developmental periods.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    ISSN: 1432-0428
    Schlagwort(e): Type 1 (insulin-dependent) diabetes mellitus ; 64,000-Mr islet protein autoantibodies ; islet cell antibodies ; autoimmune thyroid disease ; long-term diabetes
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary Autoantibodies to the 64,000-Mr (64K) islet cell protein, identified as glutamic acid decarboxylase, were assayed in 46 Type 1 (insulin-dependent) diabetic patients with a disease duration of more than 5 years. Of 46 Type 1 diabetic patients, 18 (39.1 %) were found to be positive for 64K antibodies and 12 of these patients had been diagnosed with autoimmune thyroid disease. Serum C-peptide levels were not detectable in 15 of 18 patients positive for 64K antibodies. The samples were also tested for titres of islet cell antibodies. Islet cell antibodies were detected in 15 (32.6%) of the 46 patients and all the islet cell antibody positive patients were also found to be positive for 64K antibodies. Furthermore, of these 15 patients 12 had previously been diagnosed with autoimmune thyroid disease. A correlation between levels of 64K antibodies and islet cell antibody titre revealed that higher levels of 64K antibodies were observed in patients who had higher islet cell antibody titre. These results demonstrate that most long-term Type 1 diabetic patients with 64K antibodies were also positive for islet cell antibodies complicated by autoimmune thyroid disease.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    ISSN: 1432-0428
    Schlagwort(e): Glucose transporter ; embryogenesis ; hyperglycaemia ; rat embryo culture
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Summary We investigated the expression of glucose transporter genes and protein in embryo and yolk sac during organogenesis and the regulation of glucose transporters during culture in hyperglycaemic media. Erythrocyte-type glucose transporter (GLUT 1) and brain-type glucose transporter (GLUT 3) mRNA were expressed in embryo and yolk sac. The expression of GLUT-1 and GLUT-3 mRNA was abundant on day 9–11 and day 9–10 in the embryo, respectively, and day 9–14 and day 10–11 in the yolk sac, respectively. The levels of GLUT-1 protein in the embryo increased in parallel with the expression of GLUT-1 mRNA during the corresponding period. Immunohistochemical staining of GLUT-1 protein was found principally in the neuroepithelial cells surrounding the neural tube in the embryo on day 10 and appeared in the microvessels surrounding the neural tube after day 12. To test whether the expression of glucose transporter genes and protein was suppressed during hyperglycaemia, conceptuses were cultured in high glucose medium. The abundant expression of GLUT-1 protein was not decreased during culture in high glucose media for 24 h (day 9–10) and was only down-regulated by prolonged exposure to this media for 48 h (day 9–11). We have demonstrated the predominant expression of the high affinity glucose transporter (GLUT 1 and GLUT 3) genes and (GLUT 1) protein in embryo during the early period of organogenesis. The persistently abundant expression of glucose transporter during the critical period of neural tube formation (day 9–10) even in the presence of hyperglycaemia may explain one of the mechanisms of increased glucose flux into the neuroepithelium, which may lead to neural tube defects.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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