By analyzing the hearts of quail-chick chimeras, it was found that neural crest cells at the level of occipital somites 1 to 3 migrate to the region of the aorticopulmonary septum. Bilateral removal of this neural crest population prior to migration causes malformation of the aorticopulmonary septum resulting in common arterial outflow channels or transposition of the great vessels.

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Previous studies have shown that cadmium induces a variety of grossly detectable malformations in the golden hamster including exencephaly, cleft lip and palate, amelia, micromelia and ectrodactyly. This report presents the frequency and types of underlying skeletal malformations induced by the intravenous administration of cadmium at four times during the critical stages in hamster embryo organogenesis. In general, all areas of the skeletal system are damaged by this heavy metal. This is manifested by the absence or poor development of ossification centers in different bones. Possible mechanisms of action of cadmium are discussed.

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Prior work has demonstrated that chromium trioxide is embryotoxic in hamsters if administered to pregnant animals early on the eighth gestation day. The major manifestations are cleft palate and an increased frequency of resorptions. In the present study a single iv dose (8 mg/kg) of chromium trioxide was injected into pregnant hamsters at 8 A.M. on either day 7, 8, 9, 10 or 11 of gestation in order to determine the effect of altering the time of treatment on embryotoxicity. Fetuses from females treated with chromium or demineralized-distilled water were collected on day 15 of gestation and were examined for the types and frequency of external and internal malformations. The number of resorption sites was recorded. Cleft palate, the major malformation detected, was produced only when chromium was administered on days 7, 8, or 9 of gestation. Since the frequency of resorptions and the incidence of cleft palate varied with the time of treatment it is concluded that the time at which chromium trioxide is injected into the pregnant hamster does influence embryotoxicity. The results suggest that an interference with embryonic growth may be an important factor in chromium-induced cleft palate in hamsters.

The design, synthesis and characterization of a novel nucleoamino acid derivative based on an l-tryptophanamide functionalised with a thymine nucleobase (named TrpT) is here described. The novel construct’s tendency to self-assemble into supramolecular networks in aqueous solution was demonstrated by dynamic light scattering (DLS), circular dichroism (CD), fluorescence and UV spectroscopic measurements. TrpT nanoaggregates showed good stability (up to 5 h) at 140 µM and proved to comprise species of mean hydrodynamic diameter 330 nm and a homogeneous size distribution; scanning electron microscopy (SEM) analysis further revealed these to be spherical-shaped assemblies. The ability of TrpT nanoaggregates to bind curcumin, selected as a model anticancer drug, was also evaluated and its release was monitored over time by confocal microscopy. Molecular docking studies were performed on both TrpT self-assembly and curcumin-loaded nanoaggregates suggesting that the phytomolecule can be accommodated in the interior of the supramolecular network via hydrophobic (π−π and π-alkyl) interactions; the formation of TrpT-curcumin adducts may improve the polarity of the highly-hydrophobic curcumin with a resulting logP closer to the optimal values expected for a good drug bioavailability, as estimated by the ADMETlab software. Finally, the high stability of TrpT nanoassembly in human serum, and the absence of significant toxic effects on human model cells in a cell viability assay, were also demonstrated. Despite its thymine-based scaffold, TrpT was shown not to bind adenine-bearing nucleic acids, suggesting that this interaction is hindered by its intrinsic propensity to self-assemble in preference to forming A-T base pairings. Instead, TrpT was able to interact with a serum protein such as bovine serum albumin (BSA), known to improve the bloodstream transportation and bioavailability of its cargo. Collectively, our findings support the potential use of TrpT for the development of new drug delivery systems. Graphical abstract