To demonstrate the myo-inositol depletion hypothesis in hyperglycaemia-induced embryopathy, rat conceptuses of 9.5 days of gestation in the early head-fold stage were grown in vitro during neural tube formation for 48 h with increasing amounts of glucose. The effects of an aldose reductase inhibitor and the myo-inositol supplementation were also investigated. Sorbitol and myo-inositol contents were measured in separated embryos and extra-embryonic membranes including yolk sac and amnion at the end of culture. After addition of 33.3 mmol/l and 66.7 mmol/l glucose to the culture media, the myo-inositol content of the embryos was significantly decreased by 43.1% (p less than 0.05) and 64.6% (p less than 0.01) of the control group, while a marked accumulation of sorbitol was observed (25 and 41 times that of the control). Although the addition of an aldose reductase inhibitor (0.7 mmol/l) to the hyperglycaemic culture media containing an additional 66.7 mmol/l glucose significantly reduced the sorbitol content of embryos to approximately one-eighth, the myo-inositol content of embryos remained decreased and the frequency of neural lesions was unchanged (23.1% vs 23.9%, NS). Supplementation of the myo-inositol (0.28 mmol/l) completely restored the myo-inositol content of the embryos and resulted in a significant decrease in the frequency of neural lesions (7.1% vs 23.9%, p less than 0.01) and a significant increase in crown-rump length and somite numbers. Much less significantly, sorbitol accumulation was also observed in the extra-embryonic membrane in response to hyperglycaemia, neither hyperglycaemia nor the myo-inositol supplementation modified the myo-inositol contents of the extra-embryonic membrane.(ABSTRACT TRUNCATED AT 250 WORDS)

No abstract

We have previously shown that myo-inositol depletion in the embryonic tissue at a critical stage of organogenesis has a crucial role in hyperglycemia-induced embryopathy. This study tested whether myo-inositol depletion in early organogenesis contributes to the pathogenesis of streptozocin-induced diabetic embryopathy. Rats were made diabetic by streptozocin administration before conception, and the diabetic rats were treated with diet supplemented by 2% myo-inositol or insulin from 6 to 11 gestational days during the period of maximum teratological susceptibility. In each group on the 11th gestational day, growth retardation and incidence of malformations were recorded, and myo-inositol and sorbitol content in the embryonic and extraembryonic tissues were examined. In diabetic rats, the myo-inositol content of the embryos was decreased by 36% (P less than 0.01) compared with control rats, and there was growth retardation (crown-rump length 3.37 +/- 0.04 vs. 3.87 +/- 0.03 mm, P less than 0.01; somite no. 27.5 +/- 0.2 vs. 29.1 +/- 0.2, P less than 0.01) and a significantly increased incidence of the neural lesions (17.6 vs. 1.9%, P less than 0.01). Insulin treatment resulted in near normalization of maternal serum glucose and complete restoration of myo-inositol content in the embryos with significant improvement of the growth retardation (crown-rump length 3.55 +/- 0.06 vs. 3.37 +/- 0.04 mm, P less than 0.05; somite no. 28.2 +/- 0.13 vs. 27.5 +/- 0.2, P less than 0.05) and a significantly lowered incidence of neural lesions (2.5 vs. 17.6%, P less than 0.01) compared with those of the untreated diabetic rats.(ABSTRACT TRUNCATED AT 250 WORDS)

We have previously shown that long-term exposure to medium containing insulin-induced hypoglycemic serum during the early phase of organogenesis can adversely affect embryonic development in rat embryo culture and that these effects were mediated through the interruption of glycolytic flux that constituted the principal pathway at this embryonic stage. Further experiments were performed to examine whether brief exposure to the hypoglycemic medium during critical developmental periods would have adverse effects on embryogenesis during embryo culture not only in normal but also in high glucose concentrations. Rat embryos in the early head-fold stage (9.5 days gestation) were grown in vitro for 48 h until neural tube closure occurred; dysmorphogenic lesions were not elicited in either the basal culture medium containing 6.6 mM glucose (control medium) or the hyperglycemic medium supplemented with glucose at a concentration of 33.3 mM. Hypoglycemic mediums (2.2-2.5 mM glucose) were prepared from the serum of rats given insulin intraperitoneally. Postimplantation embryos (in early neural tube formation) were briefly exposed (1 h) to hypoglycemic medium on day 10.3 of gestation during the basal culture. After exposure to the hypoglycemic medium for 1 h during culture in the control medium, embryos showed minor growth retardation and dysmorphogenic lesions (7.1% open neural pores). Exposure to the hypoglycemic medium for 1 h during culture in hyperglycemic medium suplemented with a subteratogenic concentration of glucose (33.3 mM) resulted in greater growth retardation and increased occurrence of dysmorphogenic lesions (17.3% open neural pores).(ABSTRACT TRUNCATED AT 250 WORDS)

Islet cell antibodies are usually detected in the sera of almost all Type 1 (insulin-dependent) diabetic patients within several months after onset of the disease. The antibodies then disappeared quite early during the course of the disease. The present study was undertaken to detect islet cell antibody-producing clones in peripheral blood lymphocytes of Type 1 diabetic patients whose islet cell antibodies could not be detected in sera. Epstein-Barr virus-transformed lymphocytes were employed to enhance the production of antibodies and to detect the clones from peripheral blood lymphocytes. Peripheral blood lymphocytes were obtained from 40 islet cell antibody-negative Type 1 diabetic patients, 10 antibody-positive Type 1 diabetic patients, 30 Type 2 (non-insulin-dependent) diabetic patients and 40 normal control subjects. Epstein-Barr virus-transformed lymphocytes were cultured for 4 weeks and the culture supernatants were used for assay of islet cell antibodies. Islet cell antibody assays were performed by immunohistochemical methods using peroxidase-labelled protein A for IgG antibodies, peroxidase-labelled anti-human IgM antibodies for IgM antibodies and fresh frozen human pancreatic tissue. IgG-islet cell antibodies were detected in 26 islet cell antibody-negative patients (65%), eight antibody-positive patients (80%) and one Type 2 diabetic patient (3%) in the culture supernatants. Islet cell antibodies in the supernatants could not be detected in any of the control subjects. IgM-islet cell antibodies could not be detected in any of the patients or control subjects.(ABSTRACT TRUNCATED AT 250 WORDS)