Paediatric hepatic angiosarcoma with consumptive hypothyroidism-an important diagnostic pitfall to avoid during evaluation of hepatic vascular tumours.

Hepatic angiosarcoma is an extremely rare primary malignant vascular tumour in children with very poor prognosis. Radiological diagnosis of hepatic angiosarcoma is challenging due to overlapping imaging features with other benign vascular hepatic tumours, particularly infantile hepatic haemangioma. Consumptive hypothyroidism is a condition that is almost exclusively associated with infantile hepatic haemangioma and has never been reported in angiosarcoma. We present a case of hepatic angiosarcoma in a 20-month-old girl, associated with consumptive hypothyroidism and, as a result, initially misdiagnosed as infantile hepatic haemangioma. Radiologists should be aware that consumptive hypothyroidism is not a reliable feature to use in excluding paediatric hepatic angiosarcoma. Biopsy should be performed in patients older than 1 year of age or with atypical imaging features.

Effect of hyperoxidized guanine on DNA primer-template structures: spiroiminodihydantoin leads to strand slippage.

Oxidation of guanine in DNA can lead to mutagenic lesions such as 7-hydro-8-oxoguanine (oG). Upon further oxidation, a more mutagenic lesion, spirominodihydantoin (Sp), can occur. In this study, nuclear magnetic resonance (NMR) investigations were performed to determine the structural features of DNA primer-template models with 5'-GG, 5'-G(oG), 5'-G(Sp) and 5'-T(Sp) templates, that mimic the situation in which the downstream G of the template has been oxidized to oG or hyperoxidized to Sp. Our results show that misalignment occurs only in the 5'-G(Sp) and 5'-T(Sp) templates, providing structural insights into the observed differences in mutagenicity of Sp and oG during DNA replication.

Effect of 1-methyladenine on double-helical DNA structures.

Methylation at the N1 site of adenine leads to the formation of cytotoxic 1-methyladenine (m1A). Since the N1 site of adenine is involved in the hydrogen bonding of T.A and A.T Watson-Crick base pairs, it is expected that the pairing interactions will be disrupted upon 1-methylation. In this study, high-resolution NMR investigations were performed to determine the effect of m1A on double-helical DNA structures. Interestingly, instead of disrupting hydrogen bonding, we found that 1-methylation altered the T.A Watson-Crick base pair to T(anti).m1A(syn) Hoogsteen base pair, providing insights into the observed differences in AlkB-repair efficiency between dsDNA and ssDNA.