Evaluating options in LCA: The emergence of conflicting paradigms for impact assessment and evaluation

LCA aims to help direct decisions in an environmentally sustainable direction. It indicates the environmental effects of choices and evaluates these against this background. Approaches to evaluation in LCA differ substantially, related to the way of modelling environmental effects and to the way these effects are combined into an overall judgement on alternative options. Several approaches are now operational, which are linked to different paradigms in decision making. It is shown that the choice of paradigm is quite decisive on the outcome of the analysis. Also within similar paradigms, different methods now operational may lead to different outcomes. These latter differences may be alleviated more easily than those related to paradigmatic choices, as they are partly a matter of refinement, and they partly result from legitimate differences in subjective priorities. The more basic paradigmatic differences can hardly be bridged. The practical relevancy of the subject is proven by applying different operational methods to one case, showing widely differing outcomes. The paradigm behind evaluating environmental effects is either values based, directly or through policy decisions, or economics based, as individual preferences measured in the monetary terms of willingness-to-pay. Accordingly, the different methods are “policy-oriented” or “monetary”. It may be doubted if the differences between these can be overcome in standardisation.     

Implementation of asymmetric yielding in case-specific finite element models improves the prediction of femoral fractures

Although asymmetric yielding in bone is widely shown in experimental studies, previous case-specific non-linear finite element (FE) studies have mainly adopted material behaviour using the Von Mises yield criterion (VMYC), assuming equal bone strength in tension and compression. In this study, it was verified that asymmetric yielding in FE models can be captured using the Drucker-Prager yield criterion (DPYC), and can provide better results than simulations using the VMYC. A sensitivity analysis on parameters defining the DPYC (i.e. the degree of yield asymmetry and the yield stress settings) was performed, focusing on the effect on bone failure. In this study, the implementation of a larger degree of yield asymmetry improved the prediction of the fracture location; variations in the yield stress mainly affected the predicted failure force. We conclude that the implementation of asymmetric yielding in case-specific FE models improves the prediction of femoral bone strength.     

Analysis of the subcellular localization, function, and proteolytic control of the Arabidopsis cyclin-dependent kinase inhibitor ICK1/KRP1

Recent studies have shown that cyclin-dependent kinase (CDK) inhibitors can have a tremendous impact on cell cycle progression in plants. In animals, CDK inhibitors are tightly regulated, especially by posttranslational mechanisms of which control of nuclear access and regulation of protein turnover are particularly important. Here we address the posttranslational regulation of INHIBITOR/INTERACTOR OF CDK 1 (ICK1)/KIP RELATED PROTEIN 1 (KRP1), an Arabidopsis (Arabidopsis thaliana) CDK inhibitor. We show that ICK1/KRP1 exerts its function in the nucleus and its presence in the nucleus is controlled by multiple nuclear localization signals as well as by nuclear export. In addition, we show that ICK1/KRP1 localizes to different subnuclear domains, i.e. in the nucleoplasm and to the chromocenters, hinting at specific actions within the nuclear compartment. Localization to the chromocenters is mediated by an N-terminal domain, in addition we find that this domain may be involved in cyclin binding. Further we demonstrate that ICK1/KRP1 is an unstable protein and degraded by the 26S proteasome in the nucleus. This degradation is mediated by at least two domains indicating the presence of at least two different pathways impinging on ICK1/KRP1 protein stability.     

The insect upper lip (labrum) is a nonsegmental appendage-like structure

SUMMARY The insect upper lip—the labrum—is a lobe-like structure anterior to the mouth opening. Whether the labrum represents a fused pair of segmental appendages or evolved independently is heavily debated. Here, we identify additional similarities of the regulatory gene network active in labrum and trunk appendages. However, we do not find a labral parasegment boundary and we show that labral Tc-Dll expression is independent of Tc-wg and Tc-hh signals. In contrast, Tc-Dll expression in all trunk appendages does require these signals. Finally, we identify crucial differences between the location of the labrum and trunk appendages: the labrum develops in median rather than lateral tissues and is part of an anterior nonsegmental tissue marked by and dependent on Tc-six3 activity. To reconcile these seeming contradictory results, we propose that the genetic network evolved in either labrum or trunk appendages and became redeployed at a novel location to form the other structure.     

Identification and quantitative determination of 3-chloro-2-hydroxypropylmercapturic acid and α-chlorohydrin in urine of rats treated with epichlorohydrin

Epichlorohydrin (ECH) is used in many industrial processes. Different toxic effects of ECH were found in rodents. The metabolism of ECH was investigated before in rats using [¹⁴C]ECH. The aim of this investigation was the development of non-radioactive quantitative analytical methods for measuring two urinary metabolites of ECH, namely 3-chloro-2-hydroxypropylmercapturic acid (CHPMA) and α-chlorohydrin (α-CH). The identity of CHPMA and α-CH excreted in urine of rats treated with 5 to 35 mg/kg ECH was confirmed by GC-MS. The quantitative analysis of CHPMA, involving ethyl acetate extraction from acidified urine and subsequent methylation and analysis by gas chromatography-flame photometric detection (GC-FPD), showed a method limit of detection of 2 μg/ml. The analysis of α-CH, based on ethyl acetate extraction and subsequent analysis by GC-ECD, showed a method limit of detection of 2 μg/ml. CHPMA and α-CH derivatives could be determined quantitatively down to concentrations of 0.5 and 0.4 μg/ml urine, respectively, by selected-ion monitoring GC-MS under EI conditions. Cumulative urinary excretion of CHPMA and α-CH by rats treated with ECH were found to be 31 ± 10 and 1.4 ± 0.6% (n = 13) of the ECH dose, respectively. For CHPMA, the dose-excretion relationship suggested partially saturated ECH metabolism. For α-CH, the dose-excretion relationship was linear. With fractionated urine collection it was found that approximately 74 and 84% of the total cumulative excretion of CHPMA and α-CH, respectively, took place within the first 6 h after administration of ECH. From these investigations it is concluded that the GC-FPD and GC-ECD based methods developed are sufficiently sensitive to measure urinary excretion of CHPMA and α-CH in urine from rats administered 5 to 35 mg/kg ECH. It is anticipated that the analysis of CHPMA and α-CH based on GC-MS may be sufficiently sensitive to investigate urinary excretion from humans occupationally exposed to ECH.     

Effects of chronic hypoxia on microcirculation of the central nervous system during embryonic development

In the attempt to know the factors influencing the vasculogenesis and to verify whether the vessel formation and growth are influenced, during different ontogenetic periods, by oxygen deficiency, the intraneural vascular network has been morphometrically analyzed in chicken embryo optic tectum under conditions of aerogenic hypoxia. Chicken eggs, incubated under routine conditions, have been half-painted with melted wax at the 2nd incubation day (i.d.). Fragments of optic tectum, isolated from living embryos at the 8th, 14th and 17th i.d., have been fixed and embedded according to the usual E/M procedures. A parallel series of normally developed embryos of 8, 14 and 17 incubation days has been likewise prepared. On semithin sections from the hypoxic specimens and normal control embryos the area occupied by vessels (Av), the number of vessels (Nv) and the diameter of the radially directed ones (Dv) have been evaluated. The preliminary results indicate that hypoxia evokes, from the 8th to the 17th i.d., an increment of the Av parameter, due first to microvessel neoformation and enlargement from the 8th to the 14th i.d., then from the 14th to the 17th i.d. only to a growth of new capillary branches. The response of the vascular network to the hypoxic condition is more marked from the 8th to the 14th i.d., t.i. when, in relation to the differentiation and the stratification of the neurons, the metabolic requirements of the developing tectum are presumably increased. O2 deficiency causes severe developmental disorders of the cyto- and mieloarchitecture of the tectum: the vascular response can apparently prevent actual damages only when the hypoxic condition lasts for a relatively short time.     

Minireview: The Potential of Enhanced Manganese Redox Cycling for Sediment Oxidation

Both natural and anthropogenic processes are responsible for excessive organic loading of submerged soils, with detrimental environmental consequences. The often insufficient natural attenuation can be enhanced by exploiting microbial manganese cycles. This review describes how an anoxic oxidation of organic matter with concomitant reduction of MnO ₂ can link up with a reoxidation of the resulting, soluble Mn(II) in oxic layers. The potentially attainable oxidation rates through these natural cycles are of the same order as the organic carbon accumulation rates. The microbiology and physiology of the responsible organisms are discussed, as well as examples of naturally occurring manganese cycles and the possibility to engineer this natural phenomenon.