Thyrotoxicosis affects 0.2% of pregnant women and antithyroid drugs are the treatment of choice during pregnancy. Several case reports have suggested a relationship between the prenatal use of methimazole (MMI) and choanal atresia in the offspring. However, two epidemiological studies did not find an increased teratogenic risk for MMI. This multicenter case-control study compared the frequency of maternal hyperthyroidism treated with MMI during pregnancy, in children with choanal atresia (cases) and a control group randomly selected (three matched controls according to maternal age for each case). Mothers of cases (N = 61) and controls (N = 183) were interviewed for socio-demographic questions, obstetrical and genetic history, and exposure during pregnancy to different agents; specifically detailed information regarding hyperthyroidism and MMI intake was obtained. Prenatal exposure to maternal hyperthyroidism treated with MMI was identified in 10/61 cases (16.4%) compared to 2/183 (1.1%) in the control group (OR = 17.75; CI95% = 3.49-121.40). Cases and controls did not differ in their parental degree of education, paternal occupation, twinning, maternal parity, and other exposures during pregnancy. Facial features in exposed cases showed some similarities. Our data suggest that prenatal exposure to maternal hyperthyroidism treated with MMI is associated with choanal atresia. In addition, based on our cases and a critical literature review, we propose that the mother's disease might be the causal factor and not the MMI treatment.

The conjoined twins prevalence was similar to other studies. The prevalence of diprosopus was higher. The etiology is still unknown. The presence of visceral laterality anomalies may indicate the link between diprosopus and the alteration or duplication of the primitive node in the perigastrulation period (12-15 days postfertilization). Pregnancies of more than two embryos may be a risk factor for diprosopus. Given the low prevalence of this defect, it would be useful to perform studies involving several surveillance systems and international consortiums. Birth Defects Research (Part A), 2016. © 2016 Wiley Periodicals, Inc. Birth Defects Research (Part A) 106:993-1007, 2016. © 2016 Wiley Periodicals, Inc.

We report three patients with bilateral choanal atresia in children prenatally exposed to methimazole (MMI) in order to define a MMI embryopathy clinical pattern. The combination of choanal atresia and other specific malformations strongly resembles previously reported patients exposed to MMI in utero. At present, propylthiouracil is considered the best treatment in pregnancies. However in Argentina and some other countries MMI is the only antithyroid drug, possibly posing a significant risk to the unborn fetus.

Magnetic separation has gained much attention due to its implications in different fields, becoming feasible as an alternative to existent technologies at the industrial and lab scale. Substantial efforts are focused to improve the magnetic particles used in these applications. Here we show how a relatively simple and low-cost simulation strategy (tracer simulations) can be employed to predict the effect of various key factors in magnetic separation processes, namely, particle properties and magnetic separator designs. For concreteness, we consider here specific problems in magnetic separation. The first one is the effect of different profiles of the magnetic field in the separation of magnetic nanoparticles, and the second one is the magnetophoresis of colloidal particles in a dispersion of magnetic nanoparticles.