63 research outputs found
Image Analysis and X-Ray Microanalysis in Cytochemistry
When cytochemical reaction products are homogeneously distributed within an organelle, point analyses suffice for the quantitative approach. However, quantitative analysis becomes tedious, when the elements in the reaction product are inhomogeneously distributed. Problems arise when elements from two reaction products have to be related to each other, or to endogenous cytological products (ferritin, haemosiderin, calcium, electron dense markers), either topographically or in concentration. When analyzing inhomogeneous/heteromorphical reaction product-containing organelles special attention has to be paid to measure and relate both volume and concentration. In this paper a relative simple structure (eosinophil granules) is chosen to demonstrate that the acquisition of the requested morphometrical plus chemical information and their integration is possible. The following points will be covered to acquire the morphometrical and chemical information:
a). How to estimate the total cell cross-sectioned area. b). How to estimate the total cross-sectioned area of all reaction product-containing particles inside that cell. The ratio of these two areas will provide the requested information about the particle volume fraction. By using the X-ray detector in addition: c). How to acquire the chemical information at the requested resolution, within a reasonable total acquisition time d). How to integrate the morphometrical and chemical data per organelle, by matrix analysis in a reduced scan area. e). How to acquire quantitative chemical information, by the use of cross-sectioned standards. f). How to make this acquisition method independent from changes in the instrumental conditions during the acquisition
Evaluation of contraceptive methods in women with congenital heart disease in Germany, Hungary and Japan
Aims For women with congenital heart defects (CHD), pregnancy may pose a health risk. Sexually active women with CHD without the desire for own children or for whom pregnancy would imply considerable health risks require adequate counselling regarding appropriate contraception. This study gathers data on the contraceptive behaviour of women with CHD from three different cultural regions. Methods and results 634 women with CHD from Germany, Hungary and Japan were surveyed regarding contraception and contraceptive methods (CM) used. The patients were divided into groups according to different criteria such as pregnancy associated cardiovascular risk or "safety" of the contraceptive methods used. 59% of the study participants had already gained experience with CM. The average age at the first time of use was 18.4 years; the German patients were significantly younger at the first time of using a CM than those from Hungary and Japan. Overall the condom was the method used the most (38%), followed by oral contraceptives (30%) and coitus interruptus (11%). The range of CM used in Japan was much smaller than that in Germany or Hungary. Unsafe contraceptives were currently, or had previously been used, by 29% of the surveyed patients (Germany: 25%, Hungary: 37%, Japan: 32%). Conclusion Most women with CHD use CM. There are differences between the participating countries. Adequate contraceptive counselling of women with CHD requires considering the individual characteristics of each patient, including potential contraindications. For choosing an appropriate CM, both the methods' "safety", as well as the maternal cardiovascular risk, are important. © 2015 Elsevier Ireland Ltd
The sugar phosphotransferase system of Streptomyces coelicolor is regulated by the GntR-family regulator DasR and links N-acetylglucosamine metabolism to the control of development
peer reviewedMembers of the soil-dwelling, sporulating prokaryotic genus Streptomyces are indispensable for the recycling of the most abundant polysaccharides on earth (cellulose and chitin), and produce a wide range of antibiotics and industrial enzymes. How do these organisms sense the nutritional state of the environment, and what controls the signal for the switch to antibiotic production and morphological development? Here we show that high extracellular concentrations of N-acetylglucosamine, the monomer of chitin, prevent Streptomyces coelicolor progressing beyond the vegetative state, and that this effect is absent in a mutant defective of N-acetylglucosamine transport. We provide evidence that the signal is transmitted through the GntR-family regulator DasR, which controls the N-acetylglucosamine regulon, including the pts genes ptsH, ptsI and crr needed for uptake of N-acetylglucosamine. Deletion of dasR or the pts genes resulted in a bald phenotype. Binding of DasR to its target genes is abolished by glucosamine 6-phosphate, a central molecule in N-acetylglucosamine metabolism. Extracellular complementation experiments with many bld mutants showed that the dasR mutant is arrested at an early stage of the developmental programme, and does not fit in the previously described bld signalling cascade. Thus, for the first time we are able to directly link carbon (and nitrogen) metabolism to development, highlighting a novel type of metabolic regulator, which senses the nutritional state of the habitat, maintaining vegetative growth until changing circumstances trigger the switch to sporulation. Our work, and the model it suggests, provide new leads towards understanding how microorganisms time developmental commitment
Nonpulmonary Outcomes of Asbestos Exposure
The adverse pulmonary effects of asbestos are well accepted in scientific circles. However, the extrapulmonary consequences of asbestos exposure are not as clearly defined. In this review the potential for asbestos to produce diseases of the peritoneum, immune, gastrointestinal (GIT), and reproductive systems are explored as evidenced in published, peer-reviewed literature. Several hundred epidemiological, in vivo, and in vitro publications analyzing the extrapulmonary effects of asbestos were used as sources to arrive at the conclusions and to establish areas needing further study. In order to be considered, each study had to monitor extrapulmonary outcomes following exposure to asbestos. The literature supports a strong association between asbestos exposure and peritoneal neoplasms. Correlations between asbestos exposure and immune-related disease are less conclusive; nevertheless, it was concluded from the combined autoimmune studies that there is a possibility for a higher-than-expected risk of systemic autoimmune disease among asbestos-exposed populations. In general, the GIT effects of asbestos exposure appear to be minimal, with the most likely outcome being development of stomach cancer. However, IARC recently concluded the evidence to support asbestos-induced stomach cancer to be “limited.” The strongest evidence for reproductive disease due to asbestos is in regard to ovarian cancer. Unfortunately, effects on fertility and the developing fetus are under-studied. The possibility of other asbestos-induced health effects does exist. These include brain-related tumors, blood disorders due to the mutagenic and hemolytic properties of asbestos, and peritoneal fibrosis. It is clear from the literature that the adverse properties of asbestos are not confined to the pulmonary system
Morphological and Chemical Mechanisms of Elongated Mineral Particle Toxicities
Much of our understanding regarding the mechanisms for induction of disease following inhalation of respirable elongated mineral particles (REMP) is based on studies involving the biological effects of asbestos fibers. The factors governing the disease potential of an exposure include duration and frequency of exposures; tissue-specific dose over time; impacts on dose persistence from in vivo REMP dissolution, comminution, and clearance; individual susceptibility; and the mineral type and surface characteristics. The mechanisms associated with asbestos particle toxicity involve two facets for each particle's contribution: (1) the physical features of the inhaled REMP, which include width, length, aspect ratio, and effective surface area available for cell contact; and (2) the surface chemical composition and reactivity of the individual fiber/elongated particle. Studies in cell-free systems and with cultured cells suggest an important way in which REMP from asbestos damage cellular molecules or influence cellular processes. This may involve an unfortunate combination of the ability of REMP to chemically generate potentially damaging reactive oxygen species, through surface iron, and the interaction of the unique surfaces with cell membranes to trigger membrane receptor activation. Together these events appear to lead to a cascade of cellular events, including the production of damaging reactive nitrogen species, which may contribute to the disease process. Thus, there is a need to be more cognizant of the potential impact that the total surface area of REMP contributes to the generation of events resulting in pathological changes in biological systems. The information presented has applicability to inhaled dusts, in general, and specifically to respirable elongated mineral particles
The social construction of public infrastructure
Disclosure of governmental map related information is increasingly being conceptualised as management of inter-organisational National Spatial Data Infrastructures (NSDIs). Until now, studies have been published on how NSDI projects should be designed, set up and monitored. While these approaches have gained some recognition when applied in practice, little is known about what happens when design rules are translated into daily project routines. Social scientific research into how NSDIs are defined, and how they develop and mature is scarce. This paper focuses on how infrastructure is conceptualised in NSDI projects. We present and analyse an ethnography of the development of the Dutch National Geo-information Clearinghouse (NCGI). A narrative approach is used to find out how the NCGI was conceptualised, how it emerged, developed, and changed, and how it was appraised. The research finds that actors held storyboards consisting of predefined scripts, which guided their behaviour and defined the project outcomes.OTB ResearchOTB Research Institute for the Built Environmen
Building a NGII: Balancing between infrastructure and innovation
A multitude of studies has been published on how National Geo Information Infrastructures (NGII), also known as Spatial Data Infrastructures (SDI), should be designed, set up and monitored. Scientific research on day-to-day experiences, on what is really happening in NGIIprojects is hard to find. We propose a narrative approach to elicit sensemaking processes in order to get a better understanding of NGII projects. An in-depth description and analysis on the development of the Dutch Geoportal project is given, which was funded by the Space for Geoinformation Program (SGI), meant to be part of the Dutch NGII. Intensive research was carried out through observing project meetings and conferences, and interviewing key persons, both within and outside the project environment. Out of the research data we identified different kinds of narratives, representing thinking patterns among project participants. Our ethnographic research elicits day-to-day struggles with project goals, technology, and infrastructure. We found that project participants find it hard to distinguish between requirements for infrastructure and innovation. While infrastructures need stable environments with harsh standardization that will last, innovation challenges that with new developments, reaching for something new, the uncontested terrain. We believe that this discrepancy is a cause for serious redefinitions of SDI project goals, assessment rules and results.OTB Research Institut
Balancing Infrastructure and Innovation in Geoinformation-infrastructure projects
Spatial information is increasingly exchanged between organizations within a National Geo Information Infrastructure (NGII). While a lot has been written on implementation strategies, yet little is known what really goes on in concrete projects. In this paper an ethnography is presented based on a narrative approach of a Dutch project, in which innovative technology impedes the establishment of such an infrastructure. In this project, the initial goal of building an infrastructure shifted towards applying a stream of innovative technologies, which did not help to bring about an infrastructure.OTB onderzoekOTB Research Institut
Thinking in circles: How national geo-information infrastructures cannot escape from the temptation of technology
OTB ResearchOTB Research Institute for the Built Environmen
Confocal Raman Scanning Electron Microscopy a Method for Parallel Non-Invasive High Resolution Analysis of Bone Samples
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