ABSTRACT In order to determine whether cleft foot is caused by the same niechanism as tibial and fibular ray deficiencies, clinical cases of these anomalies and those in rat fetuses induced by myleran were analyzed. In tibial and fibular ray deficiencies, arrest of tibia or fibula was closely related to the missing of toes and tibial and fibular ray deficiencies can be accepted as an occurrence of so called longitudinal deficiency. On the other hand, cleft feet were frequently associated with central polydactyly and syndactyly. In our experimental study, the critical period of formation of cleft foot was different from that of tibial ray deficiency, but it was similar to those of central polydactyly and syndactyly. It seems that cleft foot is caused by the abnormal induction of toe rays as in cleft hand and does not belong to the same group as tibial and fibular ray deficiencies.
ABSTRACT The effects of maternal hyperphenylalaninemia during pregnancy on the biochernical maturation of neonatal mice brains were examined, thus establish- ing the critical concentration of phenylalanine in maternal blood and the critical period of maternal hyperphenylalaninemia during pregnancy. Hyperphenylalanine- mia was induced by giving chow supplemented with 370, 476, 570, or 6% phenylala- nine (Phe.) and 0.12% p-chlorophenylalanine (PCPA) for at least one month and then throughout pregnancy. Some of the pregnant mice fed the 6% Phe. diet before pregnancy received a normal diet after conception (670:A). Offspring from each group were decapitated two days after birth. Their brains were removed and then divided into the cerebrum and the brain stem including the cerebellum. Total protein, RNA and DNA were measured biochemically. All kinds of markers of the newborn mice born to the 5% and 6% mothers, the weight and the contents of the protein, RNA and DNA, were reduced significantly in both the cerebrum and brain stern. In the 4% group, however, only the brain stem was affected. The 3% group showed reductions neither in the weight nor the protein and nucleic acids contents in both the cerebrum and brain stem. In the 670:A group, in which the diet was returned to normal just after conception, total protein, RNA and DNA were reduced in the brain stem, but not in the cerebrum. These results suggest that the critical concentration of maternal blood phenylalanine during pregnancy in the mouse is 1 lmg/dl, which is that corresponding to the 3% group, and also suggest that it is too late to begin the low phenylalanine diet after conception.
ABSTRACT The hemizygote of the macular mutant mouse (Ml/y) is considered to be a model of Menkes kinky hair disease (MKHD). It suffers from seizure, ataxia and emaciation, and dies around day 15 after birth. However hemizygotes which were injected with 10, 20, 20 and 30 pg of cupric chloride on days 4, 6, 8 and 10, respectively were freed from these clinical manifestations. Copper con- tents in the cerebrum, cerebellum, brain stem and liver from untreated Ml/y were significantly lower than those from normal litterniate (+/y); 1.9k0.4, 3.8+1 .O, 2.5k0.6 and 9.322.5 pg/g dry weight in Ml/y, and 7.020.7, 11.323.3, 8.621.7 and 29.1k10.4 pg/g dry weight in +/y, respectively, on day 14. On the contrary, copper contents in the kidney and intestine from Ml/y were higher than those from +/y; 35.5k10.9 and 24.3t7.7 pg/g dry weight from Ml/y, and 9.4k1.2 and 6.1k1.3 pg/g dry weight from +/y, respectively, on day 14. By electron microscopic observation, although abnormal mitochondria were now and again observed in the neurons of the spinal cord, pathological changes were not seen in the liver, kidney and intestine from Ml/y. In the treated Ml/y, the copper contents of the brain and liver were raised to between those of the Ml/y and of the +/y. The copper contents in the kidney and intestine had increased much more in the treated Ml/y, and were 5.3 and 1.6 times more than those in the Ml/y, respectively, on day 14. These results show that the distribution of copper in various organs of Ml/y is quite similar to that of the patient with MKHD, and that the copper injection raised the level of copper content in the nervous system, thus improving the clinical features of Ml/y.
ABSTRACT Pregnant mice were exposed to 6oCo gamma-irradiation on day 13 of gestation, and the offspring after birth were examined in histological sections and microvascular specimens with India ink, in order to know the pathological changes leading to postnatal manifestation of hydrocephalus. The cerebrospinal fluid pres- sure was also measured. The offspring from birth to 12 days of age showed microcephaly or dysgenetic hydrocephaly with severely deranged cerebral cortical architecture. The micro- vascular specimens of these brains showed a deranged vascular pattern and poor vascular network in the brain mantle. Its severity was in proportion to that of the disorder of the cortical architecture. These brains were involved with blood congestion and perivascular hemorrhage in the periventricular white matter, and consequently with cystic degeneration and pseudoventricle formation, which changes became evident at 7 to 10 days of age. The cerebrospinal fluid pressure was not different from that of non-treated control mice until 12 days of age. Around 14 days of age, the pressure began to increase concurrently with an external appearance of vaulted skull, indicating a transformation from degenerative ex vucuo type of hydrocephaly to progressive high-pressure hydrocephalus. These results suggested that histogenetic disorders of the cerebral cortex caused abnormal vascular formation in the brain mantle and that the consequent intra- cerebral circulatory disturbance played a significant role for degenerative changes of the brain tissue and a failure of the cerebrospinal fluid dynamics at the time of brain growth spurt.
ABSTRACT Although non-Bayesian statistical methods have been used to detect a significant increase of birth defect incidence in monitoring, they require a large number of data. In this paper Bayesian statistics is applied to estimate the incidence rate particularly in a small population. The Bayesian method is as follows. Assuming that the incidence follows a binomial distribution and the prior distribution of the incidence rate is a beta distribution, the posterior distribution of the incidence rate is a beta distribution. The hyperparameters of the prior distribution are determined objectively by the method of maximum marginal likelihood or minimum ABlC of the posterior distribution based on past observations. The Bayesian method is compared with the non-Bayesian method when applied to the monthly data of anencephaly from the birth defects monitoring program in the Tokyo Metropolitan hospitals between 1979 and 1984. The variation of the Bayesian point estimates is 25% that of the non-Bayesian ones. The average confidence interval by the Bayesian method is 29% that by the non- Bayesian method. The results indicate that the Bayesian estimation is more appropriate than the non-Bayesian estimation in this type of monitoring analysis.
ABSTRACT Neuronal migration plays a key role in forming a characteristic laminar cytoarchitecture of the neocortex. In this review, the localization of cell- surface molecules in developing murine neocortex including that of the reeler mutant were described in association with their functional significance. L1 antigen appeared solely on neurons which were placed in the intermediate zone, the cortical plate and the marginal Lone. In the cortical plate the surface of neuronal cell body was positively stained until embryonic day 17. Later on, the cell body became negative whereas cell processes in the intermediate and the marginal zones remained positive. Migrating neurons in the intermediate zone were L1 positive. N-CAM, on the contrary, were detectable on both matrix cells and neurons. The L2/HNK-1 epitope was present on endfeet of matrix cells, in addition to on the neuronal surface. In vitro perturbation assays using embryonic neocortical explants showed that the antibody for L1 could modify the rate of neuronal migration to some degree. These results suggest the functional roles of the L1 molecule in neuronal migration. However, L1 was present in the reeler mouse that is supposed to have a genetic defect in neuronal migration resulting in a disorganized cytoarchitecture. The scanning electron microscope (SEM) fractographic studies revealed a defective formation of the bundles of matrix cell processes in the developing reeler neo- cortex. Our observations indicate deranged cellular interactions among matrix cells in the reeler, although no molecular abnormalities have so far been demonstrable. The significance of cell-to-cell interactions in neocortical histogenesis was discussed.