Activation of multiple proteolysis systems contributes to acute cadmium cytotoxicity.

Cadmium exhibits both toxic and carcinogenic effects, and its cytotoxicity is linked to various cellular pathways, such as oxidative stress, ubiquitin-proteasome, and p53-mediated response pathways. The molecular mechanism(s) underlying cadmium cytotoxicity appears to be complex, but remains largely unclear. Here, we examined the effects of cadmium on the protein catabolism using two surrogate markers, DNA topoisomerases I and II alpha and its contribution to cytotoxicity. We have found that cadmium exposure induced time- and concentration-dependent decreases in the protein level of surrogate markers and therefore suggest that cadmium may be involved in proteolysis system activation. A pharmacological study further revealed the novel role(s) of these proteolytic activities and reactive oxygen species (ROS) in the cadmium-induced acute toxicity: (i) Proteasome inhibition only partially relieved the cadmium-induced proteolysis of topoisomerases; (ii) Moreover, we report for the first time that the activation of metalloproteases, serine proteases, and cysteine proteases contributes to the acute cadmium cytotoxicity; (iii) Consistent with the notion that both ROS generation and proteolysis system activation contribute to the cadmium-induced proteolysis and cytotoxicity, the scavenger N-acetylcysteine and aforementioned protease inhibition not only reduced the cadmium-induced topoisomerase degradation but also alleviated the cadmium-induced cell killing. Taken together, acute cadmium exposure may activate multiple proteolytic systems and ROS formation, subsequently leading to intracellular damage and cytotoxicity. Thus, our results provide a novel insight into potential action mechanism(s) by which cadmium exerts its cytotoxic effect and suggest potential strategies to prevent cadmium-associated acute toxicity.

Supplementary Motor Area Syndrome after Removal of an Unusual Extensive Parasagittal Meningioma: Analysis of Twelve Reported Cases.

Background and Objectives: Supplementary motor area (SMA) syndrome is a common post-operation complication in intra-axial brain tumors, such as glioma. Direct damage to parenchyma or scarification of the major vessels during an operation are the main causes. However, it is rarely reported as a postoperative complication in extra-axial tumors. Materials and Methods: We reviewed 11 reported cases of supplementary motor area syndrome after removal of extra-axial meningiomas in the English literature from the PubMed database. We also added our case, which presented as an unusual huge meningioma, to analyze the clinical parameters and outcomes of these 12 reported cases. Results: Recovery time of supplementary motor area syndrome in extra-axial tumors could be within 1-7 weeks, shorter than intra-axial tumors (2-9 weeks). Epilepsy and progressive limb weakness are the most common presentations in 50% of cases. Different degrees of postoperative muscle power deterioration were noted in the first 48 h (from 0-4). Lower limbs (66.6%, 8/12) were slightly predominant compared to upper limbs (58.3%, 7/12). Mutism aphasia was also observed in 41.6% (5/12, including our case), and occurred in tumors which were involved in the dominant side; this recovered faster than limb weakness. Discussion and Conclusions: Our work indicated that SMA syndrome could occur in extra-axial brain tumors presenting as mutism aphasia and limb weakness without any direct brain parenchyma damage. In our analysis, we found that recovery time of postoperative motor function deficit could be within 1-7 weeks. Our study also provides a further insight of SMA syndrome in extra-axial brain tumors.