Adherence to Antimicrobial Inhalational Anthrax Prophylaxis among Postal Workers, Washington, D.C., 2001

In October 2001, two envelopes containing Bacillus anthracis spores were processed at the Washington, D.C., Processing and Distribution Center of the U.S. Postal Service; inhalational anthrax developed in four workers at this facility. More than 2,000 workers were advised to complete 60 days of postexposure prophylaxis to prevent inhalational anthrax. Interventions to promote adherence were carried out to support workers, and qualitative information was collected to evaluate our interventions. A quantitative survey was administered to a convenience sample of workers to assess factors influencing adherence. No anthrax infections developed in any workers involved in the interventions or interviews. Of 245 workers, 98 (40%) reported full adherence to prophylaxis, and 45 (18%) had completely discontinued it. Experiencing adverse effects to prophylaxis, anxiety, and being <45 years old were risk factors for discontinuing prophylaxis. Interventions, especially frequent visits by public health staff, proved effective in supporting adherence

Adipocyte development and the loss of erythropoietic capacity in the bone marrow of mice after sustained hypertransfusion

In this electron microscopic study, erythropoiesis in mice was completely suppressed by repeated hypertransfusion for up to 6 wk. We describe a sequence of ultrastructural changes in the marrow's stromal cells that accompany the resulting shift from erythropoietic to granulopoietic tissue. These include the destruction of medullary macrophages, the accelerated development of marrow adipocytes and reticular cells, and a reduction in the amount of vascular space in the marrow. The absence of macrophages was highlighted by the complete lack of erythrophagocytosis in the marrows of hypertransfused mice that were injected with the hemolysing agent, phenylhydrazine. The changes in the marrow stroma probably underlie the shift in the marrow's hematopoietic microenvironment. Repeated phlebotomy of mice that had been hypertransfused for 2 wk evoked the appearance of unique stromal cells in the marrow, similar to cells that have been associated with accelerated erythropoiesis. The newly anemic mice were otherwise unable to mount an erythropoietic response to repeated bleeding, showing that the decline in the erythropoietic microenvironment brought on by sustained hypertransfusion was a lasting one.</jats:p

Adipocyte development and the loss of erythropoietic capacity in the bone marrow of mice after sustained hypertransfusion

Abstract In this electron microscopic study, erythropoiesis in mice was completely suppressed by repeated hypertransfusion for up to 6 wk. We describe a sequence of ultrastructural changes in the marrow's stromal cells that accompany the resulting shift from erythropoietic to granulopoietic tissue. These include the destruction of medullary macrophages, the accelerated development of marrow adipocytes and reticular cells, and a reduction in the amount of vascular space in the marrow. The absence of macrophages was highlighted by the complete lack of erythrophagocytosis in the marrows of hypertransfused mice that were injected with the hemolysing agent, phenylhydrazine. The changes in the marrow stroma probably underlie the shift in the marrow's hematopoietic microenvironment. Repeated phlebotomy of mice that had been hypertransfused for 2 wk evoked the appearance of unique stromal cells in the marrow, similar to cells that have been associated with accelerated erythropoiesis. The newly anemic mice were otherwise unable to mount an erythropoietic response to repeated bleeding, showing that the decline in the erythropoietic microenvironment brought on by sustained hypertransfusion was a lasting one.</jats:p

Changes in hematopoietic stem cells in bone marrow of mice with Plasmodium berghei malaria

Abstract An impaired erythropoietic response to anemia has been noted in human patients with malaria and in rodents experimentally infected with Plasmodium berghei. We have attempted to characterize the erythropoietic response in mice with a fatal P berghei infection, with particular emphasis on changes in marrow hematopoietic stem cells. Mice infected with P berghei had dramatic decreases in bone marrow cellularity, erythroblasts, BFU-E, and CFU-E as early as 24 hours postinfection and before there was any change in hematocrit. With development of anemia, marrows became erythropoietic with some expansion of the CFU-E compartment, but the BFU-E pool remained depleted and reticulocyte response was inadequate. There was no significant change in CFU-S from marrows of malaria-infected mice one day after infection. The lethality of malaria infection may take three weeks to be revealed, but it may be determined within hours of the infection by the irreparable changes in marrow erythroid stem cells.</jats:p