Ecology of the collapse of Rapa Nui society.

Collapses of food producer societies are recurrent events in prehistory and have triggered a growing concern for identifying the underlying causes of convergences/divergences across cultures around the world. One of the most studied and used as a paradigmatic case is the population collapse of the Rapa Nui society. Here, we test different hypotheses about it by developing explicit population dynamic models that integrate feedbacks between climatic, demographic and ecological factors that underpinned the socio-cultural trajectory of these people. We evaluate our model outputs against a reconstruction of past population size based on archaeological radiocarbon dates from the island. The resulting estimated demographic declines of the Rapa Nui people are linked to the long-term effects of climate change on the island's carrying capacity and, in turn, on the 'per-capita food supply'.

Therapeutic choices in patients with Ph-positive CML living in Mexico in the tyrosine kinase inhibitor era: SCT or TKIs?

A total of 72 patients with Ph-positive CML in first chronic phase were followed during a 6-year period in two different institutions in México. Among them, 22 were given a reduced-intensity allogeneic SCT, whereas 50 were given a tyrosine kinase inhibitor (TKI), mainly imatinib mesylate. The 6-year overall survival (OS) after the therapeutic intervention for patients allografted or given a TKI was 77 and 84%, respectively (P, NS); the median OS for both groups has not been reached, being above 90 and 71 months, respectively (P, NS). The freedom from progression to blast or accelerated phases was also similar for both groups, as well as the overall OS after diagnosis. Most patients allografted (91%) chose this treatment because they were unable to afford continuing treatment with the TKI, whereas most treated with the TKI (84%) were given the treatment without charge, through institutions able to pay for their treatment. The median cost of each nonmyeloablative allograft was US$18,000, an amount that is enough to cover 180 days of treatment with imatinib (400 mg per day) in México. Cost considerations favor allogeneic SCT as a 'once only' procedure whereas lifelong treatment with an expensive drug represents an excessive burden on resources.

Autologous stem cell transplantation in multiple myeloma patients <60 vs >/=60 years of age.

The role of autologous stem cell transplantation (AuSCT) in older multiple myeloma patients is unclear. Using data from the Autologous Blood and Marrow Transplant Registry, we compared the outcome of 110 patients >/=the age of 60 (median 63; range 60-73) years, undergoing AuSCT with that of 382 patients <60 (median 52; range 30-59) years. The two groups were similar except that older patients had a higher beta(2)-microglobulin level at diagnosis (P=0.016) and fewer had lytic lesions (P=0.007). Day 100 mortality was 6% (95% confidence interval 4-9) and 1-year treatment-related mortality (TRM) was 9% (6-13) in patients <60 years, compared with 5% (2-10) and 8% (4-14), respectively, in patients >/=60 years. The relapse rate, progression-free survival (PFS) and overall survival (OS) in the two groups were also similar. Multivariate analysis of all patients identified only an interval from diagnosis to AuSCT >12 months and the use of two prior chemotherapy regimens within 6 months of AuSCT as adverse prognostic factors. Our results indicate that AuSCT can be safely performed in selected older patients: the best results were observed in patients undergoing AuSCT relatively early in their disease course.

CK-19 expression by RT-PCR in the peripheral blood of breast cancer patients correlates with response to chemotherapy.

BACKGROUND: The recent introduction of sensitive RT-PCR-based techniques for the detection of epithelial antigen expression, such as CK-19, in the peripheral blood and bone marrow of breast cancer patients may provide an opportunity to evaluate tumor response at the molecular level, even in the absence of measurable disease while patients are still receiving chemotherapy. METHODS: We studied serially collected blood samples of 53 patients with breast cancer before, during, and after adjuvant, neoadjuvant, and palliative chemotherapy to evaluate its effects on the expression of CK-19 measured by RT-PCR. RESULTS: The percentage of CK-19 RT-PCR positivity decreased consistently from 43% (23/53) before chemotherapy to 14.3% (7/49), and to 18.9% (7/37) after 3 and 6 cycles, respectively (chi-square for linear trend = 7.948; p = 0.0048). Furthermore, there was a significant correlation between a negative CK-19 at three months and the response to chemotherapy (p = 0.024). CONCLUSION: We conclude that RT-PCR negativity for CK-19 expression at 3 months after the beginning of chemotherapy correlates with tumor response and, as treatment progresses, there is a significant trend for the occurrence of more negative RT-PCR results. Further studies are needed to confirm if this technique can be useful to assess response to chemotherapy in patients without measurable disease and if negativation of CK-19 expression while on chemotherapy is of prognostic significance.