Nature, extent, and impact of Superfund hazardous waste sites

Uncontrolled hazardous waste sites are major environmental and public health concerns in the United States and elsewhere. The identification and remediation of and public health responses to these sites are mandated by the U.S. federal Superfund statute. Since its enactment into law in 1980, approximately 40,000 uncontrolled waste sites have been identified in the United States. Approximately 1,300 of these sites constitute the current national Superfund priority list of sites for remediation. Results from analyses are described that characterize the priority hazardous substances released from Superfund sites and the extent of hazard posed to residential communities. Findings from the United States' experience in responding to uncontrolled waste sites are relevant to other countries as they address similar environmental and public health concerns.     

Breast conservation and prolonged chemotherapy for locally advanced breast cancer: the University of Michigan experience

PURPOSE: To determine whether breast conservation and prolonged neoadjuvant chemotherapy have efficacy in locally advanced breast cancer (LABC), as measured by survival and rate of breast conservation. MATERIALS AND METHODS: Eighty-nine patients with stage III disease were enrolled at the University of Michigan (UM) onto a prospective nonrandomized trial. Patients received nine 21-day cycles of neoadjuvant chemohormonal therapy that consisted of doxorubicin 30 mg/m2 and cyclophosphamide 750 mg/m2 intravenously on day 1, conjugated estrogens 0.625 mg orally twice daily on days 6 to 8, methotrexate 40 mg/m2 and fluorouracil 500 mg/m2 intravenously on day 8, and tamoxifen 10 mg orally twice daily on days 9 to 14. Patients with a negative biopsy received radiation only, while those with residual disease underwent mastectomy and postoperative radiotherapy. Eight more cycles of chemohormonal therapy were administered after local-regional therapy. RESULTS: The clinical response rate to neoadjuvant therapy was 97%, 28% of patients had a complete pathologic response evaluated at biopsy. Five-year overall and disease-free survival probabilities were 54% and 44%, respectively. The median disease-free survival time was 2.4 years. The 5-year actuarial rates of local-regional control with local failure as only first failure were 82% and 78% following radiotherapy, and mastectomy and radiotherapy, respectively (P = .99). CONCLUSION: Prolonged neoadjuvant chemohormonal therapy and biopsy-driven local therapy have efficacy in LABC, with 28% of patients being candidates for breast conservation and a 5-year overall survival rate of 54%.     

Identification of the cellular location of internalized Escherichia coli O157:H7 in mung bean, Vigna radiata, by immunocytochemical techniques

Escherichia coli O157:H7 has been associated with numerous outbreaks involving fresh produce. Previous studies have shown that bacteria can be internalized within plant tissue and that this can be a source of protection from antimicrobial chemicals and environmental conditions. However, the types of tissue and cellular locations the bacteria occupy in the plant following internalization have not been addressed. In this study, immunocytochemical techniques were used to localize internalized E. coli O157:H7 expressing green fluorescent protein in germinated mung bean (Vigna radiata) hypocotyl tissue following contamination of intact seeds. An average of 13 bacteria per mm(3) were localized within the sampled tissue. The bacteria were found to be associated with every major tissue and corresponding cell type (cortex, phloem, xylem, epidermis, and pith). The cortical cells located on the outside of the vascular bundles contained the majority of the internalized bacteria (61%). In addition, the bacteria were localized primarily to the spaces between the cells (apoplast) and not within the cells. Growth experiments were also performed and demonstrated that mung bean plants could support the replication of bacteria to high levels (10(7) CFU per plant) following seed contamination and that these levels could be sustained over a 12-day period. Therefore, E. coli O157:H7 can be internalized in many different plant tissue types after a brief seed contamination event, and the bacteria are able to grow and persist within the plant.     

Firing characteristics of deep layer neurons in prefrontal cortex in rats performing spatial working memory tasks

Single cells were recorded with 'tetrodes' in regions of the rat medial prefrontal cortex, including those which are targets of hippocampal afferents, while rats were performing three different behavioral tasks: (i) an eight-arm radial maze, spatial working memory task, (ii) a figure-eight track, delayed spatial alternation task, and (iii) a random food search task in a square chamber. Among 187 recorded units, very few exhibited any evidence of place-specific firing on any of the behavioral tasks, except to the extent that different spatial locations were related to distinct phases of the task. Furthermore, no prefrontal unit showed unambiguous spatially dependent delay activity that might mediate working memory for spatial locations. Rather, the cells exhibited diverse correlates that were generally associated with the behavioral requirements of performing the task. This included firing related to intertrial intervals, onset or end of trials, selection of specific arms on the eight-arm radial maze, delay periods, approach to or departure from goals, and selection of paths on the figure-eight track. Although a small number of cells showed similar behavioral correlates across tasks, the majority of cells showed no consistent correlate when recorded across multiple tasks. Furthermore, some units did not exhibit altered firing patterns in any of the three tasks, while others showed changes in firing that were not consistently related to specific behaviors or task components. These results are in agreement with previous lesion and behavioral studies in rats that suggest a prefrontal cortical role in encoding 'rules' (i.e. structural features) or behavioral sequences within a task but not in encoding allocentric spatial information. Given that the hippocampal projection to this cortical region is capable of undergoing LTP, our data lead to the hypothesis that the role of this projection is not to impose spatial representations upon prefrontal activity, but to provide a mechanism for learning the spatial context in which particular behaviors are appropriate.