Use of spleen organ cultures to monitor hemopoietic progenitor cell regeneration following irradiation and marrow transplantation

After lethal irradiation of C57BL mice followed by the injection of 10(7) marrow cells, total cellularity and progenitor cell levels exceeded pretreatment levels within 12 days in the spleen, but regeneration remained incomplete in the marrow. The exceptional regenerative capacity of progenitor populations in the spleen was observed in organ cultures of spleen slices prepared 24 hr after irradiation and transplantation, excluding continuous repopulation from the marrow as a significant factor in splenic regeneration.     

Development of twenty-one polymorphic microsatellite markers for the fungus-growing ant,Mycocepurus goeldii (Formicidae: Attini), using Illumina paired-end genomic sequencing

Obligate social parasites, or inquilines, exploit the colonies of free-living social species and evolved at least 80 times in ants alone. Most species of the highly specialized inquiline social parasites are rare, only known from one or very few, geographically isolated populations, and the sexual offspring of most inquiline species mates inside the maternal colony. Therefore, inquiline populations are believed to be small and genetically homogeneous due to inbreeding. To comparatively study the genetic diversity of the socially parasitic fungus-growing ant, Mycocepurus castrator, and its only known host species, Mycocepurus goeldii, and to infer the parasite’s conservation status, we developed 21 microsatellite markers for the host species, M. goeldii, and evaluated whether these markers cross-amplify in the social parasite, M. castrator. We isolated and characterized a total of 21 microsatellite loci for M. goeldii. The loci were screened for 24 individuals from geographically distant and genetically divergent populations in Brazil. The number of alleles per locus ranged from 18 to 4, the observed heterozygosity ranged from 0.25 to 0.636, and the probability of identity values ranged from 0.011 to 0.146. Preliminary analyses show that these markers cross amplify in the closely related social parasite species M. castrator. These newly developed loci provide tools for studying the genetic diversity and the evolution of social parasitism in the Mycocepurus host–parasite system.     

The effect of young age on tumor recurrence in the treated breast after conservative surgery and radiotherapy

Prognostic factors for local recurrence following conservative surgery and radiation therapy for patients with early breast cancer have not been fully established. To evaluate the importance of young age as a prognostic factor for local recurrence, we reviewed the results of treatment of 597 patients with 607 UICC-AJCC Stage I or II breast cancers, 47 of which were diagnosed when the patient was less than 35 years old. All were treated with excisional biopsy and a total dose to the site of the primary tumor of 60 Gy or more. The median follow-up in survivors was 63 months. Patient age and the presence of an extensive intraductal component (EIC) were both highly associated with the likelihood of tumor recurrence in the treated breast. Patients under 35 had an actuarial 5-year recurrence rate of 26%, compared to 10% for older patients (p = 0.002). Patients with an EIC had a breast recurrence rate of 25%, compared to 5% when EIC was absent (p less than 0.0001). Although the incidence of an EIC was higher in the younger subgroup (44% vs. 31%), this alone did not account for the difference in in breast recurrence rates, since younger patients had a higher recurrence rate than older patients even when an EIC was absent (22% vs. 3%, p = 0.0003). We conclude that the age of the patient is an important prognostic factor for local recurrence following conservative surgery and radiation therapy. This finding is in part attributed to the observation that younger women are more likely to have tumors with an EIC than older women, but even when an EIC is absent, they may be at an increased risk of local recurrence. However, caution is required in interpreting these findings with regard to selecting among treatment options until further data are available comparing the results of conservative surgery and radiation therapy to those of mastectomy in younger patients.