A dynamical model of the transport of asbestos fibres in the human body

We present a model for the transport of a single type of asbestos fibre through the human body. The model captures the transport modes that pertain particularly to the lungs and the mesothelium. Numerical solutions of the system follow observed movement in the body. We compare the accumulation of fibres in the lungs versus the mesothelium, and then we give analysis and results for various cases of exposure level and exposure time. Models, such as the one developed here, can give clues as to how asbestos fibres impact the body, and where to look for major impact.     

A retrospective cohort study of cancer mortality in employees of a Russian chrysotile asbestos mine and mills: Study rationale and key features

Chrysotile, a serpentine asbestos fibre, is the only type of asbestos produced and consumed in the world today. It is an established human carcinogen. We have begun fieldwork on a retrospective cohort study of employees of one of the world's largest chrysotile mine and mills, situated in Asbest, Russia. The primary aim of the study is to better characterize and quantify the risk of cancer mortality in terms of (i) the dose–response relationship of exposure with risk; (ii) the range of cancer sites affected, including female-specific cancers; and (iii) effects of duration of exposure and latency periods. This information will expand our understanding of the scale of the impending cancer burden due to chrysotile, including if chrysotile use ceased worldwide forthwith. Herein we describe the scientific rationale for conducting this study and the main features of its study design.     

Responses of antioxidants in the lichen Ramalina lacera may serve as an early-warning bioindicator system for the detection of air pollution stress

The aim of this study was to identify, in the lichen Ramalina lacera, antioxidants that could provide indications of air pollution stress, and respond earlier than traditionally used structural/physiological parameters. The pollution-sensitive lichen R. lacera was transplanted from its relatively unpolluted natural habitat to two air-polluted sites for a period of up to 6 months. The superoxide dismutase and catalase activities, total water- and lipid-soluble low-molecular-weight antioxidant capacities and chlorophyll b/chlorophyll a ratios were assessed every 6 weeks. The earliest signs of oxidative stress were detected in the activities of fungal copper/zinc-superoxide dismutase, algal iron-superoxide dismutase and water-soluble low-molecular-weight antioxidants, which increased significantly as early as 42 days after exposure to pollution. Catalase activity increased in lichens transplanted to the polluted sites after 90 days. All activities decreased towards the end of the experiment. The impact of air pollution on R. lacera, using the traditionally employed parameter of chlorophyll b/chlorophyll a ratio, was only detected after 6 months of exposure to air pollution. Our results indicate that antioxidant parameters may serve as improved early-warning indicators of air pollution stress in lichens.     

Biopersistent fiber-induced inflammation and carcinogenesis: Lessons learned from asbestos toward safety of fibrous nanomaterials

Nano-sized durable fibrous materials such as carbon nanotubes have raised safety concerns similar to those raised by asbestos. However, the mechanism by which particulates with ultrafine structure cause inflammation and ultimately cancer (e.g. malignant mesothelioma and lung cancer) is largely unknown. This is partially because the particulates are not uniform and they vary in a plethora of factors. Such variances include length, diameter, surface area, density, shape, contaminant metals (including iron) and crystallinity. Each of these factors is involved in particulate toxicity both in vitro and in vivo. Thus, the elicited biological responses are incredibly complicated. Various kinds of fibers were evaluated with different cells, animals and methods. The aim of this review is to concisely summarize previous reports from the standpoint that activation of macrophages and mesothelial injury are the two major mechanisms of inflammation and possibly cancer. Importantly, these two mechanisms appear to be interacting with each other. However, there is a lack of data on the interplay of macrophage and mesothelium especially in vivo. Since fibrous nanomaterials present potential applications in various fields, it is necessary to develop standard evaluation methods to minimize risks for human health.     

Occurrence of fungi in air and on plants in vegetation of different climatic regions in Croatia

Research was carried out onthe presence and variation in occurrence offungal genera in air and on plant samplescollected from three different climatic regionsin Croatia in relation to temperature andrelative humidity throughout one year (1998).The sampling method employed in this study wasexposure of 150 Sabouraud agar plates withantibiotics to the air for 10 min. and byplacing 10 pieces of each plant sample (N = 150)on same agar. The spores belonging to 15 fungalgenera and sterile mycelim were identified.Cladosporium (65.3–74%),Penicillium (4.43–13.9%), Alternaria(2–4.7%), and sterile mycelium (7.4–15%) werethe most prevalent fungi in the air of all threeclimatic regions, while Fusarium(20.3–36.2%) was the most prevalent fungalgenera on plant samples especially in the modestcontinental climate. Significant differenceswere obtained for comparative fungalcontamination of air and plant samples, and bycomparing monthly occurrence in all three partsincluded. The climate factors and presence ofvegetation that produce essential oils withfungicide activity may be the reason for reducedfungal contamination of outdoor environments inthe Mediterranean climate.     

Expansins in Plant Growth and Development: an Update on an Emerging Topic

Abstract: Expansins are a class of proteins identified by their ability to induce the extension of isolated plant cell walls. Expansins are encoded by an extensive multigene family in higher plants, several members of which have been shown to be expressed in a tissue-specific manner. Besides playing an apparently key role in wall expansion, and hence in cell growth, expansins have been implicated in an increasing number of processes during plant growth and development. These include: leaf organogenesis, fruit softening, and wall disassembly. A second class of closely related proteins (referred to as β-expansins) has been identified. Other recent advances in expansin research include the recovery of transgenic plants with altered level of expansins, and the production of recombinant expansins in het-erologous expression systems.     

Degradation of xenobiotic compounds in situ: Capabilities and limits

Abstract: Exploiting microorganisms for remediation of waste sites is a promising alternative to groundwater pumping and above ground treatment. The objective of in situ bioremediation is to stimulate the growth of indigenous or introduced microorganisms in regions of subsurface contamination, and thus to provide direct contact between microorganisms and the dissolved and sorbed contaminants for biotransformation. Subsurface microorganisms detected at a former manufactured gas plant site contaminated with coal tars mineralized significant amounts of naphthalene (8–43%) and phenanthrene (3–31%) in sediment-water microcosms incubated for 4 weeks under aerobic conditions. Evidence was obtained for naphthalene mineralization (8–13%) in the absence of oxygen in field samples. These data suggest that biodegradation of these compounds is occurring at the site, and the prospects are good for enhancing this biodegradation. Additional batch studies demonstrated that sorption of naphthalene onto aquifer materials reduced the extent and rate of biodegradation, indicating that desorption rate was controlling the biodegradation performance.     

Detection and identification of non-Candida albicans species in human oral lichen planus

Candida species were detected and identified in samples from the buccal mucosa, dorsal surface of the tongue and supragingival plaque of subjects with oral lichen planus (OLP). The Candida in the samples were cultured on selection agars, and identified by sequence analyses of 18S, 5.8S and 25/28S rRNA. The isolation frequency of Candida was higher in subjects with OLP than in those with healthy oral mucosa. Non-C. albicans were only isolated from people with OLP. These results support the notion that subjects with OLP are more likely to have oral colonization with Candida, and that non-C. albicans are specifically present in subjects with this condition.     

Modelling Environmental Responses of Plant Associations: A Review of Some Critical Concepts in Vegetation Study

The definition of vegetation types at different hierarchical levels, both to study the vegetation processes and for practical cartographic representation, is still considered a critical issue in many circles of plant ecologists. The problems are mainly related to the misleading idea that classification of the vegetation system, as developed by European phytosociologists during the last century within the discipline called syntaxonomy, would imply the assumption of the organismic concept of the plant community. After a short discussion on the role of Braun-Blanquet approach in plant ecology and in landscape ecology, the methods to detect multispecies responses along environmental gradients are briefly reviewed. In the main part of this article, we intend to stress that concepts considered critical, such as plant association and its ecological niche, are just operational tools that have nothing to do with the individualistic or organismic interpretation of plant communities in vegetation studies. Important to our views on vegetation, we believe that plant associations as well as the higher syntaxa can be regarded as fuzzy sets in an operational context for describing vegetation along ecological gradients in synthetic ways and can further the understanding of vegetation variation.     

Seasonal change in the above-ground phytomass of an Agrostis-with-Festuca grassland in North-east Scotland

Summary

The above-ground standing crop of an Agrostis-with-Festuca grassland near Cabrach, Banff, was measured nine times in a 16-month period by harvesting sample plots. Standing crop peaked in late summer when the weight of live graminoid phytomass reached its seasonal maximum.     

Plant intelligence: an alternative point of view

The concept of plant intelligence has been advanced by Trewavas as a potentially useful framework to guide those seeking to understand plant growth and development. In this short critique, the validity of this concept is critically assessed. Central to this critique is the proposition that the concept of the individual, to which intelligence and behaviour are intimately linked, cannot usefully be applied to plants. It is argued that the adaptive responses of plants are best appreciated if the importance of the autonomy of the individual organs is acknowledged. Although Trewavas does acknowledge the autonomy of organs by describing an individual plant as being 'a democratic confederation', that terminology implies a complexity to the interaction between organs which would demand a cogitative ability beyond that actually demonstrated in plants. It may be more appropriate to consider a plant as operating normally as a simple economic federation of many specialized economies (organs and cells). Occasionally, there can be a dramatic, and sometimes complex, reshaping of the economic balances, with the result that the fate of some or many of the individual cells will change. However, such major changes in growth and development are driven by a few simple events in an individual organ and cells. These driving events are more akin to small local revolutions in individual states than they are to democratic decisions in a sophisticated confederation.     

Modelling herbivore movement and colonization: pest management potential of intercropping and trap cropping

1 Using a stochastic simulation model, we explored the effects of agroecosystem diversity on herbivore densities. 2 Using parameters that included reproduction, colonization, and local movement rates, we simulated an insect herbivore population colonizing rows of plants in an agricultural setting. 3 Plant rows were comprised of either principal crop, intercrop, or trap crop. Herbivore parameters varied for different plant types. 4 Percent crop cover and movement rates were varied, and ensuing herbivore densities on crop rows were recorded. 5 In trap cropping schemes, both percent crop cover and movement rates were critical in determining herbivore densities. Intercropping schemes were governed primarily by colonization rates. 6 These results suggest that trap cropping schemes merit more attention than intercropping systems in the design and analysis of mixed cropping systems.     

Clara cell protein (CC16) in serum and bronchoalveolar lavage fluid of subjects exposed to asbestos

The Clara cell protein (CC16) is a small and readily diffusible protein of 16kDa secreted by bronchiolar Clara cells in the distal airspaces. These epithelial cells are altered in several pulmonary pathological processes induced by various lung toxicants. In the search for a new biomarker of asbestos-induced lung impairment, we used a sensitive immunoassay to determine the levels of CC16 in bronchoalveolar fluid (BALF) and serum of subjects exposed to asbestos compared with a group of healthy controls. In the BALF of asbestos-exposed subjects there was an insignificant trend towards CC16 elevation compared with controls, with a (mean ±SD of 0.81 ±0.65mg l^-1 for asbestos-exposed subjects (n = 23) versus 0.39 ±0.19mg l^-1 for controls (n = 11) (p = 0.09). In serum, CC16 concentration was significantly increased among asbestos-exposed subjects, with values of 27.2 ±24.0 µg l^-1 for asbestos-exposed subjects (n = 34) versus 16.1 ±7.6 µg l^-1 for controls (n = 34) (p = 0.01). Regarding the effects of smoking, there were significant differences between generally lower CC16 levels in serum and BALF (p = 0.05 and 0.001, respectively) of smokers compared with the higher levels in non-smokers. Serum CC16 levels positively correlated with those in BALF, which is consistent with a diffusional transfer of CC16 from the bronchoalveolar space into the serum. No association, however, emerged between the levels of CC16 in serum or BALF and either the duration of asbestos exposure or the severity of the lung impairment as assessed by chest X-ray. These findings suggest that exposure to asbestos elicits early changes in the local and, importantly, also the systemic levels of CC16. This pneumoprotein therefore appears as a promising non-invasive biomarker of asbestos-induced lung injury and occupational disease in both smoking and non-smoking exposed subjects.     

Inclusion of phytosociological data in an index of vegetation fire danger: application and mapping on the Karst area around Trieste (Italy)

In this paper we propose a method to produce maps of fire danger index (FDI). The index includes in the formula a vegetation pyrogenic potential index (VPPI) based on floristic phytosociological data. The map of FDI is produced by integrating available phytosociological maps of vegetation, geomorphology and climate, using the Geographic Information System technology. The method is applied to an area of the coastal Classical Karst (NE-Italy). While fire risk maps based on the incidence of previous fires are useful for facilitating emergency operations, e.g. the allocation of fire fighting resources, we conclude that the proposed index offers an effective tool to plan actions for fire prevention.     

Comparative cryptogam ecology: a review of bryophyte and lichen traits that drive biogeochemistry

BACKGROUND: Recent decades have seen a major surge in the study of interspecific variation in functional traits in comparative plant ecology, as a tool to understanding and predicting ecosystem functions and their responses to environmental change. However, this research has been biased almost exclusively towards vascular plants. Very little is known about the role and applicability of functional traits of non-vascular cryptogams, particularly bryophytes and lichens, with respect to biogeochemical cycling. Yet these organisms are paramount determinants of biogeochemistry in several biomes, particularly cold biomes and tropical rainforests, where they: (1) contribute substantially to above-ground biomass (lichens, bryophytes); (2) host nitrogen-fixing bacteria, providing major soil N input (lichens, bryophytes); (3) control soil chemistry and nutrition through the accumulation of recalcitrant polyphenols (bryophytes) and through their control over soil and vegetation hydrology and temperatures; (4) both promote erosion (rock weathering by lichens) and prevent it (biological crusts in deserts); (5) provide a staple food to mammals such as reindeer (lichens) and arthropodes, with important feedbacks to soils and biota; and (6) both facilitate and compete with vascular plants. APPROACH: Here we review current knowledge about interspecific variation in cryptogam traits with respect to biogeochemical cycling and discuss to what extent traits and measuring protocols needed for bryophytes and lichens correspond with those applied to vascular plants. We also propose and discuss several new or recently introduced traits that may help us understand and predict the control of cryptogams over several aspects of the biogeochemistry of ecosystems. CONCLUSIONS: Whilst many methodological challenges lie ahead, comparative cryptogam ecology has the potential to meet some of the important challenges of understanding and predicting the biogeochemical and climate consequences of large-scale environmental changes driving shifts in the cryptogam components of vegetation composition.