Effects of hyperglycaemia on sorbitol and myo-inositol contents of cultured embryos: treatment with aldose reductase inhibitor and myo-inositol supplementation

Inositol supplementation in premature infants with respiratory distress syndrome

BACKGROUND

Inositol influences cellular function and organ maturation. Feeding premature infants inositol-rich breast milk increases their serum inositol concentrations. Whether inositol supplementation benefits infants receiving fluids for parenteral nutrition, which are inositol-free, is not known.

METHODS

We carried out a placebo-controlled, randomized, double-blind trial to determine the effects of administering inositol (80 mg per kilogram of body weight per day) during the first five days of life to 221 infants with respiratory distress syndrome who were receiving parenteral nutrition (gestational age, 24 to 32 weeks; birth weight, less than 2000 g). All the infants were treated with mechanical ventilation and some with surfactant as well. The primary end point was survival at 28 days without bronchopulmonary dysplasia.

RESULTS

The 114 patients given inositol had significantly lower mean requirements for inspiratory oxygen (P less than 0.01) and mean airway pressure (P less than 0.05) from the 12th through the 144th hour of life than did the 107 infants given placebo. Eighty-one infants given inositol and 51 given placebo survived without bronchopulmonary dysplasia (71 vs. 55 percent; P = 0.005). In the 65 infants given surfactant, however, inositol had no effect on the degree of respiratory failure. Thirteen infants given inositol and 21 given placebo had retinopathy of prematurity (13 vs. 26 percent; P = 0.022); none of the infants given inositol had stage 4 disease, whereas 7 of those given placebo did (0 vs. 9 percent; P = 0.012). Among the infants given placebo, those who had poor outcomes (death, bronchopulmonary dysplasia, or stage 4 retinopathy of prematurity) had lower serum inositol concentrations during days 2 through 7 than those who had good outcomes (P less than 0.01).

CONCLUSIONS

The administration of inositol to premature infants with respiratory distress syndrome who are receiving parenteral nutrition during the first week of life is associated with increased survival without bronchopulmonary dysplasia and with a decreased incidence of retinopathy of prematurity.

The role of the visceral yolk sac in hyperglycemia-induced embryopathies in mouse embryos in vitro

The adverse developmental effects of hyperglycemia to rodent embryos have been shown using whole embryo culture. Although, a mechanism by which hyperglycemia-induced effects occur is unknown, recent work has focused on the visceral yolk sac as a potential target tissue. Therefore, we have evaluated the developmental effects of hyperglycemia in early head fold stage mouse embryos in vitro and assessed the histiotrophic function of the visceral yolk sac. As has been previously shown in rodents, hyperglycemia produced neural tube closure defects in a concentration dependent manner at 33, 50, and 67 mM glucose using a 44 h exposure period. However, exposure times between 6 and 12 h were sufficient to alter embryonic development when the glucose concentration was 50 or 67 mM. In contrast, early somite stage embryos (4-6 somite stage) appear to be less sensitive to dysmorphogenesis and a 48 h exposure to 67 mM glucose but not 33 or 50 mM also produced neural tube defects. Hyperglycemia (67 mM) did not alter the uptake of 35S-methionine and 35S-cysteine-labeled hemoglobin (35S-Hb) in the visceral yolk sac (VYS) in early headfold staged embryos. However, the accumulation of 35S in the embryo was reduced by 16-18% at glucose concentrations of 50 or 67 mM during the last 12 h of a 44 h exposure period. No effect on VYS uptake or embryonic accumulation of 35S-labeled products was observed at shorter exposure periods (12-24 and 24-36 h).(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of hyperglycemia on mitochondrial morphology in the region of the anterior neuropore in the explanted rat embryo model: evidence for a modified Reid hypothesis as a mechanism for diabetic teratogenesis

Congenital malformations are the leading cause of the increased perinatal mortality in the infants of insulin-dependent diabetic mothers. The mechanisms(s) of diabetic teratologic development has yet to be defined. Hyperglycemia is known to depress aerobic metabolism in many organisms and cell lines. Reid hypothesized that exposure to hyperglycemia could result in decreased mitochondrial biogenesis in embryonic cells. Should these cells suddenly be changed to an environment of lower glucose concentration, decreased energy capabilities would exist until sufficient numbers of mitochondria could be regenerated. Such cells may not be capable of meeting temporal-spatial requirements, thereby resulting in structural abnormalities. In our study the explanted rat embryo model demonstrated that in the head-fold region hyperglycemia produced morphologic alterations of mitochondria but no difference in the number of mitochondria per cell. Specifically, embryos cultured in euglycemia demonstrated orthodox mitochondrial configuration, whereas those cultured in hyperglycemia had mitochondria in a condensed configuration. These findings were reversible. A modification of Reid's original hypothesis may provide an explanation for the mechanism of diabetic teratologic development.

Protection by free oxygen radical scavenging enzymes against glucose-induced embryonic malformations in vitro

This study addresses the possibility that the teratogenic effects of a diabetic pregnancy are associated with increased embryonic activities of free oxygen radicals. Rat embryos were cultured in 50 mmol/l glucose for 48 h and subsequently showed pronounced growth retardation and severe malformations. The enzyme inducer citiolone and the free oxygen radical scavenging enzymes superoxide dismutase, catalase and glutathione peroxidase protected against the disturbed growth and development of the embryos at 50 mmol/l glucose when added to the culture media. Enzymatic measurements indicated that citiolone induced an increased activity of superoxide dismutase in the embryonic tissues and that the added enzymes were taken up by both the yolk sac and the embryo proper. The protection against embryonic maldevelopment was thus conferred by agents that increased the free oxygen radical scavenging capacity of the embryonic tissues. The results suggest that a high glucose concentration in vitro causes embryonic dysmorphogenesis by generation of free oxygen radicals. An enhanced production of such radicals in embryonic tissues may be directly related to the increased risk of congenital malformations in diabetic pregnancy.