ABSTRACT Leptin is a hormone that reduces food intake and increases energy expenditure by acting on the arcuate nucleus in the hypothalamus. Recent studies indicated that the neuronal circuit related to food intake in the hypothalamus is formed in the neonatal period and that leptin is necessary for the formation of this circuit. Our studies have further suggested that leptin may act on the fetal cerebral cortex, including the cingulate cortex, which is involved in motor and cognitive processes, and that leptin may affect maintenance and differentiation of neural stem cells, glial-restricted progenitor cells and/or neuronal lineage cells. These recent studies showed that leptin not only has homeostatic functions in adults, but also regulates brain development in the prenatal and neonatal periods. These findings suggest that leptin is related to formation of the normal brain structure and regenerative potency of neural cells as well as the predisposition to homeostatic dysfunction, low locomotor activity or impairment of cognitive function.
ABSTRACT A hypothesis is presented that the association between maternal influenza and other causes of fever during the second trimester of pregnancy and the subsequent development of schizophrenia in the child is due to the damage caused by hyperthermia to the developing amygdalohippocampal complex and associated structures in the fetal brain. Hyperthermia is a known cause of congenital defects of the central nervous system and other organs after sufficiently severe exposures during early organogenesis. The pathogenic mechanisms include death of actively dividing neuroblasts, disruption of cell migration and arborization and vascular damage. In experimental studies, hyperthermia during later stages of central nervous system development also caused damage to the developing brainstem that was associated with functional defects. This damage usually results in hypoplasia of the parts undergoing active development at the time of exposure. Recent studies have shown no evidence of direct invasion of the fetus by the influenza virus. Factors that might interact with hyperthermia include familial liability to schizophrenia, season of birth, maternal nutrition, severe stress and medications used to alleviate the symptoms of fevers. The time of the development of the fetal amygdalohippocampal complex and the changes found in its structure and associated areas of the brain are compatible with the known effects of hyperthermia.
ABSTRACT The gene responsible for the polydactyly/arhinencephaly (Pdn/Pdn) mouse, which exhibits polysyndactyly and arhinencephaly and has a 13.2% risk of neural tube defects (NTD), has been identified as Gli3. Ochratoxin A (OTA) is a teratogen causing NTD in mice. When Pdn/Pdn embryos were exposed to 2 mg/kg of OTA on day 7.5, the incidence of NTD in Pdn/Pdn fetuses increased to 51.6%. Pre-treatment with folinic acid (FA), metabolically the most active form of folic acid, before OTA-treatment decreased the incidence of NTD to 20.8%. We investigated the effect of OTA and FA on gene expression in day 9 embryos using whole-mount in situ hybridization and real-time PCR. Over-expression of Fgf8 was observed at the anterior neural ridge (ANR) in the non-treated Pdn/Pdn. Over-expression at the ANR expanded in the OTA-treated Pdn/Pdn, and it was ameliorated by pretreatment with FA. Emx2 signal was observed in the dorsal forebrain in the non-treated +/+, but disappeared in the OTA-treated +/+, and was recovered by FA. The Emx2 signal was pale and the expression amount was depressed in the non-treated and OTA-treated Pdn/Pdn embryos. It was suggested that down-regulation of Gli3 induced the over-expression of Fgf8 at the ANR, that OTA treatment accelerated the over-expression, and that pretreatment with FA ameliorated the OTA-induced over-expression of Fgf8 in the Pdn/Pdn. It was also suggested that down-regulation of Gli3 induced the down-regulation of Emx2 in the Pdn/Pdn. It was further speculated that the over-expression of Fgf8 at the ANR and down-regulation of Emx2 in the dorsal forebrain may contribute to NTD induction.
ABSTRACT The aim of the investigation was to describe chromosomal inversions identified by a birth defects registry with respect to chromosomes involved, pregnancy outcome, method of diagnosis, inheritance, sex and diagnosis of major structural birth defects. Cases were derived from a population-based birth defects registry in Hawaii and comprised all infants and fetuses with chromosomal deletions delivered during 1986–2002. A total of 68 cases were identified through a statewide birth defects registry in Hawaii during 1986–2002. The chromosomes involved in the greatest proportion of inversions were chromosomes 6 (18%) and 9 (18%). Live births accounted for 62 (91%) of the cases. Diagnosis was made by amniocentesis or chorionic villus sampling in 60 (88%) of the cases. Of the 43 cases with known inheritance, the inversion was inherited in 40 (93%) and de novo in three (7%). Males accounted for 31 (46%) and females for 37 (54%) of the cases. Major structural birth defects were identified in 12 (18%) of the cases. Inversions diagnosed among infants and fetuses in Hawaii do not appear to affect all chromosomes equally. Most detected inversions occurred among live births and were inherited conditions. Infants and fetuses with inversions are not frequently associated with major structural birth defects.
ABSTRACT Iniencephaly is a rare congenital malformation consisting of a complex alteration of the embryonic development occurring around the third post-fertilization week and characterized by a hyper-retroflexion of the cephalic pole. We report a case of iniencephaly associated with acrania-encephalocele, spina bifida and abnormal ductus venosus in a fetus with trisomy 18 diagnosed at 12 week's gestation in a 41-year-old woman. A co-occurrence between aneuploidy and iniencephaly was documented and polymorphisms on folate metabolism-related genes were investigated in the parents to assess possible etiologic factors and recurrence risk for neural tube defects (NTD). An homozygous state for the MTRR polymorphism was diagnosed in the mother, identifying a clinical risk for NTD. Once iniencephaly or any other NTD are suspected, genetic analysis, second level ultrasound and fetal karyotype are recommended. Autopsy should also be performed in all cases of early ultrasound-based diagnosis of fetal malformations.
ABSTRACT We describe a 5-year-old girl with features resembling Trichorhinophalangeal syndrome, type I (sparse scalp hair, bushy eyebrows, bulbous nose, long philtrum, cone-shaped epiphyses, clinobrachydactyly, epiphyseal changes in the femoral head and short stature), and appendicular exostoses similar to trichorhinophalangeal syndrome, type II. However, despite physical resemblance to the trichorhinophalangeal syndrome variants, cytological analysis showed a structurally normal chromosome 8 and no mental deficiency was apparent. In addition, morphological congruities between multiple exostoses and metachondromatosis was indicated from radiographic findings.
ABSTRACT Prenatal development of Kbl:Dutch rabbits was studied in comparison with Kbl:New Zealand white rabbits. Significantly accelerated ossification of the 5th and 6th sternebrae and a low incidence of fetuses with a 13th rib were characteristic features in the prenatal development of Kbl:Dutch rabbits in comparison with Kbl:New Zealand white rabbits. These characteristics were largely consistent with earlier studies of Dutch rabbits from different suppliers and are notable when Kbl:Dutch rabbits are used for the evaluation of skeletal ossification.