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Abstract. Of particular interest is the observation that cleavage of double-stranded plasmid DNA occurs even at very low concentrations of 1 (2.5 µM), under physiological conditions (optimum pH of 7.0), with a rate enhancement of 2.7×10 7 over the uncatalyzed reaction. Thus, 1 is one of the most effective model complexes to date, mimicking the function of nucleases.

Despite low mortality rates, nodal recurrence in papillary thyroid carcinoma occurs in up to 20 % of patients. Emerging evidences indicate that dysregulated microRNAs are implicated in the process of metastasis. In the present study, we investigated whether miR-9, miR-10b, miR-21 and miR-146b levels are predictive of papillary thyroid carcinoma recurrence. Using macro-dissection followed by quantitative real-time PCR, we measured miR-9, miR-10b, miR-21 and miR-146b expression levels in formalin-fixed, paraffin-embedded samples of 66 patients with papillary thyroid carcinoma categorized into two groups: the recurrent group (n = 19) and the non-recurrent group (n = 47). All patients underwent total thyroidectomy and were followed for at least 120 months after surgery to be considered recurrence-free. Univariate and multivariate analysis were performed using the Cox proportional hazard model in order to identify associations between multiple clinical variables and microRNA expression levels and papillary thyroid carcinoma recurrence. MiR-9 and miR-21 expression levels were found to be significant prognostic factors for recurrence in patients with papillary thyroid carcinoma (HR = 1.48; 95 % CI 1.24-1.77, p < 0.001; and HR = 1.52; 95 % CI 1.18-1.94, p = 0.001; respectively). Multivariate analysis involving the expression level of miR-9 and miR-21 and various clinical parameters identified the expression of these microRNAs as independent prognostic factors for papillary thyroid cancer patients. In conclusion, our results support the potential clinical value of miR-9 and miR-21 as prognostic biomarkers for recurrence in papillary thyroid carcinoma.

The design and development of suitable biomimetic catalytic systems capable of mimicking the functional properties of enzymes continues to be a challenge for bioinorganic chemists. In this study, we report on the synthesis, X-ray structures, and physicochemical characterization of the novel isostructural [Fe III Co ] complex as the catalytically active species in diester hydrolysis reactions. Kinetic studies on the hydrolysis of the model substrate bis(2,4-dinitrophenyl)phosphate by 1 and 2 show Michaelis-Menten behavior, with 2 being 35% more active than 1. In combination with k H /k D isotope effects, the kinetic studies suggest a mechanism in which a terminal M III -bound hydroxide is the hydrolysis-initiating nucleophilic catalyst. In addition, the complexes show maximum catalytic activity in DNA hydrolysis near physiological pH. The modest reactivity difference between 1 and 2 is consistent with the slightly increased nucleophilic character of the Ga