Mediastinal small cell carcinoma: a unique clinical entity?

PURPOSE: Mediastinal small cell carcinoma (MSCC) is a rare tumor with limited published literature. In view of diagnostic confusion pertaining to this tumor, we investigated its origin, clinical features, management and survival. METHODS: Clinical data of MSCC patients were retrospectively reviewed. Eligible patients showed pathologically proven small cell carcinoma (SCC) with the primary lesions confined to the mediastinum. Survival information was collected through follow-up studies. RESULTS: Among 25 MSCC patients identified, 22 were classified to have limited disease (LD), while 3 were with extensive disease (ED). The 5 patients (20%) underwent surgery and 20 patients (80%) underwent non-surgical treatment. The 4 patients with LD MSCC received chemotherapy alone, while 13 of them received chemoradiotherapy. Overall median survival time (MST) of all patients was 22 months, and the 1-, 3- and 5-year overall survival rates were 67.4, 16.8, and 8.4%, respectively. The MST of LD and ED patients separately was 23 and 8 months, respectively, with significant difference (P = 0.005). But, the MST of patients who received surgical and non-surgical treatment was 25 and 21 months, respectively, with no significant difference (P = 0.757). The MST of LD patients receiving chemotherapy and chemoradiotherapy was 12 and 29 months, respectively, but somehow did not show significant difference (P = 0.482). CONCLUSIONS: Our data suggested that MSCC may be a separate clinical entity like extrapulmonary small cell carcinomas (EPSCCs). Despite, multimodal treatment is currently the main treatment option, but for patients with LD MSCC, chemoradiotherapy is recommended to be preferred treatment modality.

Genetic diversity and differentiation of the endangered and endemic species Sauvagesia rhodoleuca in China as detected by ISSR analysis.

Sauvagesia rhodoleuca (Ochnaceae) is an endangered plant that is endemic to southern China. The levels of genetic variation and patterns of population structure in S. rhodoleuca were investigated using inter-simple sequence repeat markers. Eleven primers were used to amplify DNA samples from 117 individuals, and a total of 92 loci were detected. Our results indicated that genetic diversity was quite low both at the species level (percentage of polymorphic bands (PPB) = 41.30%, Nei's gene diversity (h) = 0.1331, and Shannon information index (I) = 0.2028) and the population level (PPB = 16.30-28.26%, h = 0.0496-0.1012, and I = 0.0756-0.1508). A high level of genetic differentiation among populations was detected based on Nei's genetic diversity analysis (0.4344) and analysis of molecular variance (47.03%). The low genetic diversity within population and high population differentiation of S. rhodoleuca were assumed to result largely from limited gene flow, genetic drift, inbreeding, and clonal growth. Conservation strategies for this endangered species are proposed based on the genetic data.

Interactions between rare-earth ions and DNA of Bashibai sheep.

The interaction between rare-earth ions and DNA from Bashibai sheep was studied by microcalorimetry and electrochemistry. The DNA chain was found to have four to five binding sites for rare-earth ions. The binding affinity was about 10⁻5-10⁻6 M. It was also found that smaller ions caused more heat to be released in the process of binding and bound more readily to the nucleic acid chain. This is attributed to the enhanced ability of polarization of smaller ions and reduced steric hindrance compared to larger ions. The electrochemistry results show that rare-earth ions could be inserted into the DNA helix, producing a new complex with electrochemically active groups. The rare-earth ions and DNA complex reached equilibrium after a 90-min incubation at room temperature.