Citations

AbstractHematopoietic stem cells (HSCs) can both self renew and differentiate into precursors of all types of blood cells. HSCs are divided into an active pool and a quiescent reserve. Cells selected for the active pool contribute to hematopoiesis for many years. Mutations in HSCs can lead to neoplasms such as chronic myeloid leukemia, although the risk of neoplastic HSC disorders varies across mammals. We use allometric scaling relations combined with mutation-selection evolutionary dynamics to determine which mammalian species is most resistant to HSC disorders. We find that the advantage of large mammals at escaping the selective pressure of cancer cells is insufficient to overcome the increased risk of acquiring mutations. Hence, mutation dominates, which favors smaller stem-cell pools and, consequently, smaller mammals, since these minimize the development of mutations in the active stem-cell pool. Consequently, the smaller the active stem-cell pools, the better.

Background and Purpose— Even though endovascular coils have been widely used for the treatment of intracranial aneurysms, the cellular and molecular responses of aneurysms to the coils after embolization remain poorly understood. The aim of the present study was to understand the mechanism of apoptosis in aneurysms embolized with platinum coils in the rabbit model of elastase-induced aneurysms. Methods— Elastase-induced saccular aneurysms were created at the origin of the right common carotid artery in 30 rabbits. Aneurysms were allowed to mature for 8 weeks, after which 20 aneurysms were embolized with platinum coils by endovascular means. After 2 (n=10) and 4 (n=10) weeks of implantation, aneurysm samples harboring coils were harvested for apoptotic studies. The remaining 10 uncoiled aneurysms were used as controls; additional controls included the left common carotid artery, which had not undergone any surgical procedure. Control samples were harvested at 12 weeks after aneurysm creation. Results— Expression of procaspases-3, -8, and -9 was elevated in coiled aneurysms embolized with platinum coils at both time points when compared with uncoiled aneurysms and the left common carotid artery. Cleaved caspases-3, -8, and -9 were found to be expressed only at 4 weeks after embolization. Cells within the aneurysm cavity were terminal dUTP nick end-labeling–positive at 4 weeks only. These apoptotic cells were identified as smooth muscle actin–positive cells. Expression of tumor necrosis-α was high in coiled aneurysms when compared with controls. There was no significant difference in the expression of Fas ligand among groups. Decreased expression of antiapoptotic proteins Bcl-2 and phospho-Bad, as well as increased expression of proapoptotic proteins Bax and Bid, was observed in coiled aneurysms at both time points. Conclusions— Activation of apoptosis in aneurysms after embolization with platinum coils is induced by both tumor necrosis factor-α–mediated extrinsic and Bcl-2-mediated intrinsic pathways.

AbstractBackground: Assay of methylated DNA markers in stool is a promising approach for colorectal cancer (CRC) screening. A method to capture hypermethylated CpG islands from stool would enrich target analyte and allow optimal assay sensitivity.Methods: Methyl-binding domain (MBD) protein was produced using a pET6HMBD plasmid with MBD DNA sequence cloned from rat MeCP2 gene and bound to a column of nickel-agarose resin. We first established the feasibility of using the MBD column to extract methylated human DNA in a high background of fecal bacterial DNA. To explore the impact of MBD enrichment on detection sensitivity, the tumor-associated methylated vimentin gene was assayed with methylation-specific PCR from stools to which low amounts of cancer cell DNA (0–50 ng) were added and from stools from CRC patients and healthy individuals. Stools from cancer patients were selected with low amounts of human DNA (median 7 ng, range 0.5–832 ng).Results: With MBD enrichment, methylated vimentin was detected in stools enriched with ≥10 ng of cancer cell DNA and in CRC stool with a range of native human DNA amounts from 4 to 832 ng. Without MBD enrichment, methylated vimentin was not detected in the enriched stools and was detected in only 1 cancer stool with high human DNA (832 ng). In stools from healthy individuals methylated vimentin was not detected, with or without MBD enrichment.Conclusions: MBD capture increases assay sensitivity for detecting methylated DNA markers in stool. Applied clinical studies for stool cancer screening are indicated.

Purpose We update Radiation Therapy Oncology Group trial 8911 (USA Intergroup 113), a comparison of chemotherapy plus surgery versus surgery alone for patients with localized esophageal cancer. The relationship between resection type and between tumor response and outcome were also analyzed. Patients and Methods The chemotherapy group received preoperative cisplatin plus fluorouracil. Outcome based on the type of resection (R0, R1, R2, or no resection) was evaluated. The main end point was overall survival. Disease-free survival, relapse pattern, the influence of postoperative treatment, and the relationship between response to preoperative chemotherapy and outcome were also evaluated. Results Two hundred sixteen patients received preoperative chemotherapy, 227 underwent immediate surgery. Fifty-nine percent of surgery only and 63% of chemotherapy plus surgery patients underwent R0 resections (P = .5137). Patients undergoing less than an R0 resection had an ominous prognosis; 32% of patients with R0 resections were alive and free of disease at 5 years, only 5% of patients undergoing an R1 resection survived for longer than 5 years. The median survival rates for patients with R1, R2, or no resections were not significantly different. While, as initially reported, there was no difference in overall survival for patients receiving perioperative chemotherapy compared with the surgery only group, patients with objective tumor regression after preoperative chemotherapy had improved survival. Conclusion For patients with localized esophageal cancer, whether or not preoperative chemotherapy is administered, only an R0 resection results in substantial long-term survival. Even microscopically positive margins are an ominous prognostic factor. After a R1 resection, postoperative chemoradiotherapy therapy offers the possibility of long-term disease-free survival to a small percentage of patients.