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Thank you for visiting our website. We are a relatively small lab with big ideas. We are part of a much larger group of investigators known collectively as the LLUMC Molecular Radiation Biology Laboratories. It is our hope that this website will educate, communicate, and incite scientific debate. As the PI of our little group, I hope to post our data and discuss potential mechanisms, consequences, and countermeasures. With a bit of luck we'll all learn something. The links to the left include our merry band as well as collaborating investigators and laboratories. The links to the right include our archive and blogroll. The banner above will always bring you back to the main page page. Take a look around and please feel free to leave a comment on our blog (try to keep it civil and constructive) or shoot us an e-mail. - Michael " Ubertramp " Pecaut
Lab Update
Posted by: Ubertramp on 2009.02.10
Categories & Tags: Department of Energy,Grant Proposal,High-Energy Iron Radiation,Immunity,Microgravity,Mouse,NASA,NIH,New Publication,Radiation,Space Shuttle
Comments: None
Well, I’ve been on and off vacation for the last month or so. But a lot has been going on since my last update.
First, the bad news. Both NIH and DOE have turned down my grant proposals. I will probably try to resubmit the NIH grant this summer once I figure out how to address some of the reviewer concerns. I gotta keep remembering that being a scientist requires a thick skin and a short memory when it comes to rejection. Good thing I’m showing signs of early onset Alzheimer’s. Hah!
I still haven’t heard back from NASA regarding my Mice In Space proposal. I’m not sure what is holding it up. My guess is the recent economic issues have made spaceflight an even more difficult prospect than usual. Plus, they may be trying to work out a way to blend two or more proposals together. Given the lack of funds for science in general, this is probably harder than it sounds.
We also haven’t heard from LLU regarding our NMTB grant proposal. Seems LLU got a lot more proposals than they expected and they are having a harder time deciding who gets what. They may also be debating cutting the funding cap in order to fund more individual projects. I have no idea.
On to the good news. Farnaz had or Oral Defense a few weeks ago. We invited my mentor from CU, Monika Fleshner, to sit on her committee along with several investigators from LLU including Penelope Duerksen-Hughes, Denise Bellinger, and Daila Gridley. With all those smart people in the room, I think I was at least as nervous as Farnaz. Hah. It was pretty grueling, as you might expect, but she passed. Now she’s in the process of analyzing the rest of her data and addressing the committee concerns.
Also, our publication list keeps growing. One of these days I’ll have to update our publications page. For now, here are the abstracts from PubMed to latest few. They include immune, bone, radiation and spaceflight related data. They also demonstrate our continued collaborations with Ted Bateman at Clemson University, Keith Chapes at Kansas State, as well as Louis Stodieck and Ginger Ferguson at the University of Colorado at Boulder:
Radiation and secondary immune response to lipopolysaccharide.
Pecaut MJ, Gridley DS.
BACKGROUND: The purpose of this study was to determine whether secondary immune responses to lipopolysaccharide (LPS) were altered by exposure to radiation. MATERIALS AND METHODS: C57BL/6 mice were irradiated (60Co, gamma-rays) to 0 or 3 Gray (Gy) and injected intraperitoneally with LPS on days 10 and 42 thereafter. Subsets were euthanized 0-14 days after the second injection for analyses. RESULTS: The data show numerous radiation-induced effects, as well as some significant interactions among radiation, LPS, and day of analysis. Among the most striking were changes in thymus mass, circulating lymphocytes, monocytes, granulocytes, and specific lymphocyte subpopulations, erythrocyte counts, hematocrit, and platelet counts and volume. Spontaneous blastogenesis and oxidative burst capacity of phagocytic cells, however, were relatively normal. CONCLUSION: The findings indicate that exposure to radiation at a spaceflight relevant dose can influence the distribution of certain leukocyte populations in response to a secondary challenge with LPS.
Spaceflight effects on T lymphocyte distribution, function and gene expression.
Gridley DS, Slater JM, Luo-Owen X, Rizvi A, Chapes SK, Stodieck LS, Ferguson VL, Pecaut MJ.
The immune system is highly sensitive to stressors present during spaceflight. The major emphasis of this study was on the T lymphocytes in C57BL/6NTac mice after return from a 13-day space shuttle mission (STS-118). Spleens and thymuses from flight animals (FLT) and ground controls similarly housed in animal enclosure modules (AEM) were evaluated within 3-6 h after landing. Phytohemagglutinin-induced splenocyte DNA synthesis was significantly reduced in FLT mice when based on both counts per minute and stimulation indexes (P < 0.05). Flow cytometry showed that CD3(+) T and CD19(+) B cell counts were low in spleens from the FLT group, whereas the number of NK1.1(+) natural killer (NK) cells was increased (P < 0.01 for all three populations vs. AEM). The numerical changes resulted in a low percentage of T cells and high percentage of NK cells in FLT animals (P < 0.05). After activation of spleen cells with anti-CD3 monoclonal antibody, interleukin-2 (IL-2) was decreased, but IL-10, interferon-gamma, and macrophage inflammatory protein-1alpha were increased in FLT mice (P < 0.05). Analysis of cancer-related genes in the thymus showed that the expression of 30 of 84 genes was significantly affected by flight (P < 0.05). Genes that differed from AEM controls by at least 1.5-fold were Birc5, Figf, Grb2, and Tert (upregulated) and Fos, Ifnb1, Itgb3, Mmp9, Myc, Pdgfb, S100a4, Thbs, and Tnf (downregulated). Collectively, the data show that T cell distribution, function, and gene expression are significantly modified shortly after return from the spaceflight environment.
Shifts in bone marrow cell phenotypes caused by spaceflight.
Ortega MT, Pecaut MJ, Gridley DS, Stodieck LS, Ferguson V, Chapes SK.
Bone marrow cells were isolated from the humeri of C57BL/6 mice after a 13-day flight on the space shuttle Space Transportation System (STS)-118 to determine how spaceflight affects differentiation of cells in the granulocytic lineage. We used flow cytometry to assess the expression of molecules that define the maturation/activation state of cells in the granulocytic lineage on three bone marrow cell subpopulations. These molecules included Ly6C, CD11b, CD31 (platelet endothelial cell adhesion molecule-1), Ly6G (Gr-1), F4/80, CD44, and c-Fos. The three subpopulations were small agranular cells [region (R)1], larger granular cells (R2), which were mostly neutrophils, and very large, very granular cells (R3), which had properties of macrophages. Although there were no composite phenotypic differences between total bone marrow cells isolated from spaceflight and ground-control mice, there were subpopulation differences in Ly6C (R1 and R3), CD11b (R2), CD31 (R1, R2, and R3), Ly6G (R3), F4/80 (R3), CD44(high) (R3), and c-Fos (R1, R2, and R3). In particular, the elevation of CD11b in the R2 subpopulation suggests neutrophil activation in response to landing. In addition, decreases in Ly6C, c-Fos, CD44(high), and Ly6G and an increase in F4/80 suggest that the cells in the bone marrow R3 subpopulation of spaceflight mice were more differentiated compared with ground-control mice. The presence of more differentiated cells may not pose an immediate risk to immune resistance. However, the reduction in less differentiated cells may forebode future consequences for macrophage production and host defenses. This is of particular importance to considerations of future long-term spaceflights.
Spaceflight-relevant types of ionizing radiation and cortical bone: Potential LET effect?
Lloyd SA, Bandstra ER, Travis ND, Nelson GA, Bourland JD, Pecaut MJ, Gridley DS, Willey JS, Bateman TA.
Extended exposure to microgravity conditions results in significant bone loss. Coupled with radiation exposure, this phenomenon may place astronauts at a greater risk for mission-critical fractures. In a previous study, we identified a profound and prolonged loss of trabecular bone (29-39%) in mice following exposure to an acute, 2 Gy dose of radiation simulating both solar and cosmic sources. However, because skeletal strength depends on trabecular and cortical bone, accurate assessment of strength requires analysis of both bone compartments. The objective of the present study was to examine various properties of cortical bone in mice following exposure to multiple types of spaceflight-relevant radiation. Nine-week old, female C57BL/6 mice were sacrificed 110 days after exposure to a single, whole body, 2 Gy dose of gamma, proton, carbon, or iron radiation. Femora were evaluated with biomechanical testing, microcomputed tomography, quantitative histomorphometry, percent mineral content, and micro-hardness analysis. Compared to non-irradiated controls, there were significant differences compared to carbon or iron radiation for only fracture force, medullary area and mineral content. A greater differential effect based on linear energy transfer (LET) level may be present: high-LET (carbon or iron) particle irradiation was associated with a decline in structural properties (maximum force, fracture force, medullary area, and cortical porosity) and mineral composition compared to low-LET radiation (gamma and proton). Bone loss following irradiation appears to be largely specific to trabecular bone and may indicate unique biological microenvironments and microdosimetry conditions. However, the limited time points examined and non-haversian skeletal structure of the mice employed highlight the need for further investigation.
I suppose that’s it for now. We have a couple more publications already in review (including at least one more spaceflight & immune paper) and we are preparing several more for submission.
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