Fetal exencephaly arising as a result of preimplantation exposure to ammonium chloride.

OBJECTIVES: To investigate the effect of preimplantation exposure to 0.6 mM ammonium chloride on both preimplantation and postimplantation development of (F1 x F1) strain mouse embryos. METHOD: Two-cell stage mouse embryos were randomly allocated to culture in either M16 medium or M16 added with 0.6 mM ammonium chloride for 2 days before being transferred to 2.5 day pseudopregnant recipients. Embryo morphology was assessed after 1 and 2 days of culture. The recipient females were sacrificed on day 15.5 of gestation. The number of implantation sites, fetuses, moles and any gross abnormalities found were noted. RESULTS: There was no significant difference in the number of embryos reaching morula stage after two days of culture between the two groups (chi2=0.86, P>0.05). Implantation and pregnancy loss rates between the two groups were within comparable ranges. Crown-rump length was significantly higher in the group of embryos exposed to ammonium chloride (t=2.46, P<0.05). There was one gross abnormality, exencephaly, detected in the experimental group (4.35% per fetus obtained). CONCLUSIONS: Besides the abnormal increase in fetal size, preimplantation exposure to ammonium chloride also resulted in gross abnormality, exencephaly. If such effects occurred in the course of human in vitro fertilization, it could be devastating. Further study in this aspect is, therefore, clinically very important in preventing unwanted abnormalities that could arise from human in vitro fertilization.

Esvaziamento gástrico e acidose metabólica: III. Estudo da retençäo gástrica de uma soluçäo de citrato de sódio, utilizando um modelo experimental de acidose metabólica em ratos / Gastric emptying and metabolic acidosis: III. Study of gastric retention of a sodium citrate solution using an experimental model of metabolic acidosis in rats

O esvaziamento gástrico de uma soluçäo de citrato de sódio 0,25 mEq/ml, acrescida de fenol vermelho (6mg/dl), foi estudado em raias Wistar com acidose metabólica, induzida por infusäo orogástrica prévia de soluçäo de cloreto de amônio 0,5M. Como grupos controles foram utilizados animais com infusäo orogástrica prévia de soluçäo de cloreto de sódio 0,5M de água. Nas refeiçöes právias e de prova, o volume empregado foi de 2ml/100g de peso animal. As retençöes gástricas foram avaliadas 6 horas após a infusäo das refeiçöes prévias, nos tempos de 5, 10, 20 e 30 minutos, pela avaliaçäo da concentraçäo do marcador presente no resíduo gástrico. Os resultados mostraram que as retençöes gástricas da soluçäo de citrato de sódio, nos animais com acidose metabólica, näo mostraram diferenças significativas em relaçäo aos controles. Os resultados sugerem uma açäo preponderante do mecanismo de receptores duodenais para o pH da refeiçäo sobre as possíveis alteraçöes da acidose metabólica, impostas à motilidade gastrica