Arthrogryposis multiplex congenita in utero: radiologic and pathologic findings.

Arthrogryposis multiplex congenita (AMC) refers to the development of multiple joint contractures affecting two or more areas of the body prior to birth. It affects approximately 1 in 3000 individuals, mostly reported in individuals of Asian, African and European descent with equal incidence in males and females. Arthrogryposis is associated with over 400 medical conditions and 350 known genes with considerable variability in phenotypic expression. The primary underlying mechanism is decreased fetal movement during development. Prenatal imaging is crucial in early diagnosis by identifying fetal movement limitations and the presence of club foot or joint contractures. Postnatal autopsy confirms the diagnosis and extent of associated congenital anomalies and provides a valuable source of DNA material. Molecular methods are particularly useful in delineating novel gene mutations, locus heterogeneity and phenotype genotype correlation. Prenatal evaluation with early diagnosis via image scanning and further genetic surveillance give the opportunity for family counseling concerning future pregnancy management and expected neonatal morbidity and mortality.

Metal speciation in anoxic sediments: when sulfides can be construed as oxides.

Metal speciation in aquatic sediments is often characterized using wet chemical sequential extraction techniques. However, these methods are operationally defined and subject to artifacts, particularly when dealing with anoxic sediments, in which metal sulfide precipitates are likely to occur. Using X-ray absorption spectroscopy (XAS) and acid-volatile sulfide (AVS) analysis, we evaluated the effectiveness of one of the most widely used sequential extraction protocols, the Tessier method, at determining Zn and Pb speciation in anoxic wetland sediments. Sequential extraction results significantly underestimated the amount of Zn associated with sulfide phases as compared to the other two approaches. XAS analysis of ZnS amended sediments indicates that the most likely source of this conflict is an early dissolution of amorphous metal sulfide phases during the sequential extraction step corresponding to the extraction of iron and manganese oxides. The reagent mixture used in this step, hydroxylamine hydrochloride-HCl, is widely used in other sequential extraction protocols, including the BCR method, limiting their application to anoxic sediments. For this reason, current sequential extraction techniques should only be used on anoxic sediments with caution, and/or in conjunction with complementary approaches to assess metal speciation.