Toxicokinetics of aflatoxin in pregnant mice.

Our objective was to study the toxicokinetics of aflatoxin (AF) in pregnant mice. Aflatoxin B1 (AFB1) was administered intraperitoneally (IP) to groups of pregnant mice in single doses of 20 mg/kg on gestation day (GD) 13 and orally at the same gestational age. Controls received (IP and oral) a proportionate volume of solvent only. Maternal blood was collected at 15, 30, 45, 60, 90, 120, and 150 minutes posttreatment. Their AFB1 contents were determined. Aflatoxin B1 concentrations following maternal exposure to AFB1 were highly correlated with time after exposure. The serum concentrations were predictable and the highest serum levels were seen immediately at 15 minutes in mice given AFs IP and at 30 minutes in those given it orally. The absorption was 5.0 microg/min and elimination was 3.0 microg/min. The toxicokinetics of AFB1 have been delineated. Aflatoxins are easily and rapidly absorbed both from the gastrointestinal tract (GI) tract and through the peritoneum.

Intrauterine growth restriction and skeletal variations in mouse fetuses induced by vigabatrin administered at preimplantation stages of development.

Epileptic women do not withdraw antiepileptic drug (AED) therapy during pregnancy, therefore, exposure to AED during preimplantation stages might result in considerable embryonic concentrations endangering development. Neither clinical nor experimental research has addressed this important issue adequately. Vigabatrin (VGB), a second generation AED, is both effective and well tolerated as an add-on therapy in epilepsy with partial seizures. However, there is little data on the possible reproductive toxicity of this widely used drug. The objective of the present study was to evaluate the effects of VGB on pregnancy and pregnancy outcome in an experimental model. VGB was administered in single doses of 450 mg/kg intraperitoneally (i.p.) to groups of mice on one of gestation days (GD) 1, 3, or 5. The treated animals consumed moderately reduced amounts of food and water on the day of treatment, so the controls were saline-injected and food and water-restricted to match the amounts consumed by the experimental animals. All animals were killed on GD 18. VGB treatment did not interfere with implantation, nor did it cause significant embryo resorption. However, it caused significant reduction in fetal bodyweight and increased frequency of growth restricted fetuses which weighed two standard deviations (SD) less than the mean of the controls. The VGB group fetuses also had retarded development of the skeletal system in terms of delay in maturity of the suproccipital bone development, cervical and coccygeal vertebral hypoplasia, and poor ossification of the bones of the fore and hind paws. Another major finding was the increased incidence of minor malformations, such as the presence of cervical ribs and sternal anomalies. The results of this study show that VGB administered at preimplantation stages of development causes intrauterine growth restriction (IUGR) and augments minor malformation rates in mice. Future studies must address the mechanisms of VGB-induced IUGR and minor malformations.

Beneficial effect of supplemental lipoic acid on diabetes-induced pregnancy loss in the mouse.

Uncontrolled diabetes mellitus (DM) is an etiological factor for recurrent pregnancy loss, fetal growth disorders, and major congenital malformations in the offspring. Antioxidant therapy has been advocated to overcome the oxidant-antioxidant disequilibrium inherent in diabetes. The objective of this article was to evaluate the beneficial effects of alpha-lipoic acid (LA) on fetal outcome in a mouse model of streptozotocin (STZ)-induced DM. Timed pregnant mice were made diabetic by intraperitoneal (IP) injection of a single dose of STZ (200 mg/kg) on gestation day (GD) 2. Diabetic animals were supplemented daily with an IP injection of 15 mg/kg of LA starting on GD 4 and continued through GD 12. Fetuses were examined on GD 18 for malformations and growth restriction. Some diabetic mice injected with Evans blue were examined on GD 3.5 and GD 6.5 to evaluate frequency of implantations. STZ-treated mice had all cardinal signs of DM. LA treatment did not normalize blood glucose levels of DM mice. Rates of pregnancy in saline control, DM, and DM + LA groups were 90%, 28%, and 64%, respectively, indicating that LA promotes pregnancy in DM animals. However, postimplantation resorption showed a threefold increase in the DM + LA group. Rates of intrauterine growth restriction and major congenital malformations were also augmented thus indicating that the interaction between DM and LA has deleterious effects on postimplantation embryos.

Mitochondrial dysmorphology in the neuroepithelium of rat embryos following a single dose of maternal hyperthermia during gestation.

Hyperthermia is teratogenic to human and animal embryos and induces mainly anomalies of the nervous system. However, the teratogenic mechanism is poorly understood. Mammalian embryos are known to switch from anaerobic to aerobic metabolism around the time of neural tube closure. This critical event might be sensitive to hyperthermia. The objective of the present study was to evaluate the ultrastructural changes of the mitochondria of the neuroepithelium (NE) of rat embryos following maternal exposure to hyperthermia. Pregnant rats were heat stressed for an hour on gestation day (GD) 9 and embryos were examined by electron microscopy on GD 10. NE presented extensive apoptosis. Intercellular junctions were weakened and copious cellular debris projected into the ventricle. The mitochondria were of diverse size and shape. Most of them were swollen and had short cristae and electron dense matrix. Hydropic changes were also observed in numerous mitochondria. Lipid-laden mitochondria were found in the apical portions of neuroblasts. The mesenchyme (ME) of heat-treated embryos showed paucity of cells and only as frequent apoptosis as the controls. Their mitochondria also showed changes similar to those of the NE. Additionally extensive lipid accumulation was observed in and in the vicinity of mitochondria, often surrounded by short strands of endoplasmic reticulum. Whereas mitochondrial pathology was associated with profound apoptosis in the NE, growth restriction and lipid accumulation accompanied mitochondrial changes in the ME. The results of this study indicate that the embryonic response to maternal heat shock is tissue-specific and morphologically distinct in this species.

Etiology, pathogenesis and prevention of neural tube defects.

Spina bifida, anencephaly, and encephalocele are commonly grouped together and termed neural tube defects (NTD). Failure of closure of the neural tube during development results in anencephaly or spina bifida aperta but encephaloceles are possibly post-closure defects. NTD are associated with a number of other central nervous system (CNS) and non-neural malformations. Racial, geographic and seasonal variations seem to affect their incidence. Etiology of NTD is unknown. Most of the non-syndromic NTD are of multifactorial origin. Recent in vitro and in vivo studies have highlighted the molecular mechanisms of neurulation in vertebrates but the morphologic development of human neural tube is poorly understood. A multisite closure theory, extrapolated directly from mouse experiments highlighted the clinical relevance of closure mechanisms to human NTD. Animal models, such as circle tail, curly tail, loop tail, shrm and numerous knockouts provide some insight into the mechanisms of NTD. Also available in the literature are a plethora of chemically induced preclosure and a few post-closure models of NTD, which highlight the fact that CNS malformations are of hetergeneitic nature. No Mendelian pattern of inheritance has been reported. Association with single gene defects, enhanced recurrence risk among siblings, and a higher frequency in twins than in singletons indicate the presence of a strong genetic contribution to the etiology of NTD. Non-availability of families with a significant number of NTD cases makes research into genetic causation of NTD difficult. Case reports and epidemiologic studies have implicated a number of chemicals, widely differing therapeutic drugs, environmental contaminants, pollutants, infectious agents, and solvents. Maternal hyperthermia, use of valproate by epileptic women during pregnancy, deficiency and excess of certain nutrients and chronic maternal diseases (e.g. diabetes mellitus) are reported to cause a manifold increase in the incidence of NTD. A host of suspected teratogens are also available in the literature. The UK and Hungarian studies showed that periconceptional supplementation of women with folate (FA) reduces significantly both the first occurrence and recurrence of NTD in the offspring. This led to mandatory periconceptional FA supplementation in a number of countries. Encouraged by the results of clinical studies, numerous laboratory investigations focused on the genes involved in the FA, vitamin B12 and homocysteine metabolism during neural tube development. As of today no clinical or experimental study has provided unequivocal evidence for a definitive role for any of these genes in the causation of NTD suggesting that a multitude of genes, growth factors and receptors interact in controlling neural tube development by yet unknown mechanisms. Future studies must address issues of gene-gene, gene-nutrient and gene-environment interactions in the pathogenesis of NTD.

Ultra-structural morphological abnormalities of the urinary bladder in streptozotocin-induced diabetic female rats.

The objective of this study was to evaluate the ultra-structural changes in the urinary bladder of diabetic rats in relation to disease duration since the morphological bases of diabetes-induced bladder dysfunction are poorly understood. Urinary bladders were examined chronologically by electron microscopy in a female Wistar-rat model of streptozotocin-induced diabetes mellitus and compared to control samples. Numerous dark mitochondria with swollen cristae and electron lucent, large, calcified and degenerated mitochondria were observed first in the urothelium. Intraepithelial capillaries surrounded by thick collagen were also present. Gap junctions between myocytes were interrupted or extensively widened with reduced mitochondria and caveolae. Collagen accumulation, degenerated nerve fibres and myelin bodies were seen between myocytes with increased collagen content and frequent mast cells, phagocytes and lymphocyte aggregates in the stroma. All ultra-structural lesions became augmented with longer duration of diabetes. Diabetes induces time-dependent pathologic changes in the urinary bladder of rats that might account for bladder dysfunction.

Birth prevalence and pattern of osteochondrodysplasias in an inbred high risk population.

BACKGROUND: Define the pattern and birth prevalence of the different types of osteochondrodysplasias in newborn infants in the United Arab Emirates (UAE) population, which is highly inbred and where termination of pregnancy is not accepted. METHODS: All infants with a birth weight of 500 gm and above in the three hospitals in Al Ain Medical District of the UAE were studied prospectively over a period of 5 years. For each live birth or stillbirth with suspected skeletal dysplasia, a detailed clinical and radiological examination was carried out. Pregnancy history and information regarding parental age, ethnic origin, family history, and level of consanguinity were obtained and a pedigree was constructed. RESULTS: Among the 38,048 births during the study period, 36 (9.46/10,000 births) had some type of skeletal dysplasia. Eighteen cases were attributed to autosomal recessive genes (4.7/10,000 births), 10 were due to apparent new dominant mutations (2.62/10,000), five were autosomal dominant type (1.3/10,000) and one was X-linked dominant type (0.26/10,000). In three cases, inheritance was unknown. The most common recessive type of skeletal dysplasia in our series was fibrochondrogenesis (1.05/10,000), followed by chondrodysplasia punctata (0.78/10,000). The birth prevalence rate of skeletal dysplasia doubled in the last 2 years of the 5-year observation period (6.74/10,000 in 1996 vs. 12.86/10,000 in 1999, and 13.45/10,000 in 2000). This increase involved cases caused by new dominant mutations, and occurred mainly in the first half of 1999. CONCLUSION: This prospective study has identified a high birth prevalence of skeletal dysplasia, and risk factors are postulated. These findings represent an accurate birthprevalence figure and a useful baseline for this group of birth defects in the UAE.