Structure-Function Relationships in Radiation-Induced Cell and Tissue Lesions: Special References to the Contributions of Scanning Electron Microscopy and Hematopoietic Tissue Responses

Contributions of scanning electron microscopy to the field of radiation biology are briefly reviewed and presented in terms of an overall goal to identify and characterize the structural features of radiation-induced lesions in vital cell and tissue targets. In the context of lesion production, the major radiation-elicited response sequences, the types and nature of measured end points, and governing temporal and radiobiological parameters are discussed and illustrated by using results derived from both in vitro cell systems and in vivo studies that measured tissue responses from various organ systems (respiratory, digestive, circulatory, and central nervous systems). Work in our laboratory on the nature of early and late hematopathologic tissue responses (aplastic anemia and myeloid leukemia) induced by protracted radiation exposure and the bridging effect of repair processes relative to the expression of these pathologies is highlighted

Economics knowledge, attitudes and experience of student teachers in Scotland

There is a move away from teaching economics as a separate subject in Scotland. It is now mainly taught within Business Management courses in upper secondary school and is embedded within several subject areas in both primary and early secondary curricula, a move that is in step with broader curricular aims to break down barriers among subjects. This writing discusses the need for clearly situated teaching and learning of economics, provided by teachers provided by teachers who have sufficient background knowledge to devise effective contexts for learning, whether or not it is taught as a discrete subject. The results of a survey of student teachers' levels of economic literacy are analysed and recommendations made for the preparation of teachers to deal effectively with embedded approaches to teaching about economics

Alpha-Particle Irradiation-Induced Change in Bronchopulmonary Macrophage Morphology, In Vitro

Bronchopulmonary macrophages, isolated from canine lungs by saline lavage and grown in tissue culture for short periods, were acutely irradiated with a range of doses of either Americium-241 alpha particles (0.03-48 Gy) or 250 keV x-rays (0.5-24 Gy). Following a 24-hour reincubation and expression period, cells were examined for radiation-induced changes in overall viability, as well as in cell morphology and ultrastructure. Results indicated that neither quality of radiation had much effect on cell viability over dose ranges examined, but substantial changes in cell volume, surface topography, and cytoplasmic features were noted, especially in the alpha-particle-irradiated specimens. Results support the concept that the limiting plasma membrane of the targeted macrophage is a sensitive subcellular target for ionizing radiation, especially high-linear-energy-transfer heavy particles

SEM of Canine Chromosomes: Normal Structure and the Effects of Whole-Body Irradiation

Canine chromosomes are not only numerous (38 autosomal pairs), but they are small (compared to human chromosomes) and morphologically similar as well. Analysis of the canine karyotype by light microscopy (LM) of banded chromosomes is, thus, difficult, and the literature on the canine karyotype is scanty. In this study, we describe examination of chromosomes from normal and chronically irradiated dogs with the scanning elect ran microscope (SEM). Metaphase chromosomes from bone marrow aspirates were Giemsa-banded with either 0.025% trypsin alone or 0.1% trypsin preceded by 10% H2O2 and prepared for SEM. Examination of chromosomes from normal dogs revealed cylindrical chromosome profiles with well-defined chromatids and centromeres. The chromosome arms were consistently marked by periodic grooves that had complementary structures on sister chromatids and may represent the trypsin-sensitive chromatic regions. The quality of the preservation varied from preparation to preparation and depended on the concentration and time of trypsin treatment. Chromosomes from irradiated dogs revealed translocations, deletions, and gaps. We conclude that SEM produces images superior to LM images of canine chromosomes; SEM images can be used not only to identify individual chromosomes, but also to identify genetic lesions in the chromosomes of chronically irradiated dogs. We further conclude that the two Giemsa-banding protocols used in the present study produced variable results, although 0.025% trypsin alone appeared to give better and more consistent results than 0.1% trypsin preceded by 10% H2O2

The bloodstream differentiation - division of Trypanosoma brucei studied using mitochondrial markers

In the bloodstream of its mammalian host, the African trypanosome Trypanosoma brucei undergoes a life cycle stage differentiation from a long, slender form to a short, stumpy form. This involves three known major events: exit from a proliferative cell cycle, morphological change and mitochondrial biogenesis. Previously, models have been proposed accounting for these events (Matthews & Gull 1994a). Refinement of, and discrimination between, these models has been hindered by a lack of stage-regulated antigens useful as markers at the single-cell level. We have now evaluated a variety of cytological markers and applied them to investigate the coordination of phenotypic differentiation and cell cycle arrest. Our studies have focused on the differential expression of the mitochondrial enzyme dihydrolipoamide dehydrogenase relative to the differentiation-division of bloodstream trypanosomes. The results implicate a temporal order of events: commitment, division, phenotypic differentiation

Integrating food security into public health and provincial government departments in British Columbia, Canada

Food security policy, programs, and infrastructure have been incorporated into Public Health and other areas of the Provincial Government in British Columbia, including the adoption of food security as a Public Health Core Program. A policy analysis of the integration into Public Health is completed by merging findings from 48 key informant interviews conducted with government, civil society, and food supply chain representatives involved in the initiatives along with relevant documents and participant/direct observations. The paper then examines the results within the context of historic and international trends and theoretical models of food policy, community food security, and applied policy research. Public Health re-emerged as a driver of food security in BC—both as a key player and in positing the public’s health as a driver in food security and food systems. While Public Health’s lead role supported an increase in legitimacy for food security in BC, interviewees described a clash of cultures between Public Health and civil society. The clash of cultures occurred partly as a result of Public Health’s limited food security mandate and top down approach. Consequently civil society voice at the provincial level was marginalized. A social policy movement toward a new political paradigm—regulatory pluralism—calls for greater engagement of civil society, and for all sectors to work together toward common goals. A new, emerging policy map is proposed for analyzing the dynamics of food security and health promotion initiatives in BC