Bestimmung von Fumonisinen in komplexen Lebensmittelmatrices mittels Accelerated Solvent Extraktion (ASE)

Accelerated solvent extraction (ASE) is an alternative sample extraction procedure for fumonisins in corn and corn products. ASE gave results comparable to that of a draft CEN method, but required less extraction time. Furthermore, ASE gave significantly higher quantitative values than another method reported for extraction of fumonisins (Trucksess et al., 1995).     

Individualized,discrete event,simulations provide insight into inter- and intra-subject variability of extended-release,drug products

Objective

Develop and validate particular, concrete, and abstract yet plausible in silico mechanistic explanations for large intra- and interindividual variability observed for eleven bioequivalence study participants. Do so in the face of considerable uncertainty about mechanisms.

Methods

We constructed an object-oriented, discrete event model called subject (we use small caps to distinguish computational objects from their biological counterparts). It maps abstractly to a dissolution test system and study subject to whom product was administered orally. A subject comprises four interconnected grid spaces and event mechanisms that map to different physiological features and processes. Drugs move within and between spaces. We followed an established, Iterative Refinement Protocol. Individualized mechanisms were made sufficiently complicated to achieve prespecified Similarity Criteria, but no more so. Within subjects, the dissolution space is linked to both a product-subject Interaction Space and the GI tract. The GI tract and Interaction Space connect to plasma, from which drug is eliminated.

Results

We discovered parameterizations that enabled the eleven subject simulation results to achieve the most stringent Similarity Criteria. Simulated profiles closely resembled those with normal, odd, and double peaks. We observed important subject-by-formulation interactions within subjects.

Conclusion

We hypothesize that there were interactions within bioequivalence study participants corresponding to the subject-by-formulation interactions within subjects. Further progress requires methods to transition currently abstract subject mechanisms iteratively and parsimoniously to be more physiologically realistic. As that objective is achieved, the approach presented is expected to become beneficial to drug development (e.g., controlled release) and to a reduction in the number of subjects needed per study plus faster regulatory review.

     

Finite volume analysis of temperature effects induced by active MRI implants: 2. Defects on active MRI implants causing hot spots

Background

Active magnetic resonance imaging implants, for example stents, stent grafts or vena cava filters, are constructed as wireless inductively coupled transmit and receive coils. They are built as a resonator tuned to the Larmor frequency of a magnetic resonance system. The resonator can be added to or incorporated within the implant. This technology can counteract the shielding caused by eddy currents inside the metallic implant structure. This may allow getting diagnostic information of the implant lumen (in stent stenosis or thrombosis for example). The electro magnetic rf-pulses during magnetic resonance imaging induce a current in the circuit path of the resonator. A by material fatigue provoked partial rupture of the circuit path or a broken wire with touching surfaces can set up a relatively high resistance on a very short distance, which may behave as a point-like power source, a hot spot, inside the body part the resonator is implanted to. This local power loss inside a small volume can reach ¼ of the total power loss of the intact resonating circuit, which itself is proportional to the product of the resonator volume and the quality factor and depends as well from the orientation of the resonator with respect to the main magnetic field and the imaging sequence the resonator is exposed to.

Methods

First an analytical solution of a hot spot for thermal equilibrium is described. This analytical solution with a definite hot spot power loss represents the worst case scenario for thermal equilibrium inside a homogeneous medium without cooling effects. Starting with this worst case assumptions additional conditions are considered in a numerical simulation, which are more realistic and may make the results less critical. The analytical solution as well as the numerical simulations use the experimental experience of the maximum hot spot power loss of implanted resonators with a definite volume during magnetic resonance imaging investigations. The finite volume analysis calculates the time developing temperature maps for the model of a broken linear metallic wire embedded in tissue. Half of the total hot spot power loss is assumed to diffuse into both wire parts at the location of a defect. The energy is distributed from there by heat conduction. Additionally the effect of blood perfusion and blood flow is respected in some simulations because the simultaneous appearance of all worst case conditions, especially the absence of blood perfusion and blood flow near the hot spot, is very unlikely for vessel implants.

Results

The analytical solution as worst case scenario as well as the finite volume analysis for near worst case situations show not negligible volumes with critical temperature increases for part of the modeled hot spot situations. MR investigations with a high rf-pulse density lasting below a minute can establish volumes of several cubic millimeters with temperature increases high enough to start cell destruction. Longer exposure times can involve volumes larger than 100 mm³. Even temperature increases in the range of thermal ablation are reached for substantial volumes. MR sequence exposure time and hot spot power loss are the primary factors influencing the volume with critical temperature increases. Wire radius, wire material as well as the physiological parameters blood perfusion and blood flow inside larger vessels reduce the volume with critical temperature increases, but do not exclude a volume with critical tissue heating for resonators with a large product of resonator volume and quality factor.

Conclusion

The worst case scenario assumes thermal equilibrium for a hot spot embedded in homogeneous tissue without any cooling due to blood perfusion or flow. The finite volume analysis can calculate the results for near and not close to worst case conditions. For both cases a substantial volume can reach a critical temperature increase in a short time. The analytical solution, as absolute worst case, points out that resonators with a small product of inductance volume and quality factor (Q V_ind < 2 cm³) are definitely save. Stents for coronary vessels or resonators used as tracking devices for interventional procedures therefore have no risk of high temperature increases. The finite volume analysis shows for sure that also conditions not close to the worst case reach physiologically critical temperature increases for implants with a large product of inductance volume and quality factor (Q V_ind > 10 cm³). Such resonators exclude patients from exactly the MRI investigation these devices are made for.     

Ecological restoration: A new frontier for nature conservation and economics

Ecological restoration is still perceived by many conservationists, and the majority of economists, as a diversion, a delusion, and – far worse – a waste of money. In this paper we point out that restoration is in fact complementary not only to nature conservation but also to sustainable, equitable socio-economic development. This is because restoring and augmenting the natural capital base generates jobs and improves livelihoods and the quality of life of all in the economy.

In developing countries, where most biodiversity hotspots occur, both conservation of nature and the restoration of degraded ecosystems will find local support only if they are clearly linked to socio-economic development. Conversely, sound socio-economic development in the environmentally damaged portions of those countries undoubtedly will require ecological restoration of the natural capital base. Nature conservation, ecological restoration, and sustainable economic development policies should therefore be planned, budgeted and executed conjointly.     

Bridging Restoration Science and Practice: Results and Analysis of a Survey from the 2009 Society for Ecological Restoration International Meeting

Developing and strengthening a more mutualistic relationship between the science of restoration ecology and the practice of ecological restoration has been a central but elusive goal of SERI since its inaugural meeting in 1989. We surveyed the delegates to the 2009 SERI World Conference to learn more about their perceptions of and ideas for improving restoration science, practice, and scientist/practitioner relationships. The respondents' assessments of restoration practice were less optimistic than their assessments of restoration science. Only 26% believed that scientist/practitioner relationships were “generally mutually beneficial and supportive of each other,” and the “science–practice gap” was the second and third most frequently cited category of factors limiting the science and practice of restoration, respectively (“insufficient funding” was first in both cases). Although few faulted practitioners for ignoring available science, many criticized scientists for ignoring the pressing needs of practitioners and/or failing to effectively communicate their work to nonscientists. Most of the suggestions for bridging the gap between restoration science and practice focused on (1) developing the necessary political support for more funding of restoration science, practice, and outreach; and (2) creating alternative research paradigms to both facilitate on‐the‐ground projects and promote more mutualistic exchanges between scientists and practitioners. We suggest that one way to implement these recommendations is to create a “Restoration Extension Service” modeled after the United States Department of Agriculture's Cooperative Extension Service. We also recommend more events that bring together a fuller spectrum of restoration scientists, practitioners, and relevant stakeholders.     

Characterization of Three Plasmid Deoxyribonucleic Acid Molecules in a Strain of Streptococcus faecalis: Identification of a Plasmid Determining Erythromycin Resistance

Three plasmids designated alpha, beta, and gamma, distinguishable by their molecular weights (6, 17, and 34 million, respectively) were isolated from Streptococcus faecalis strain DS-5 (ATCC 14508). Derivatives of this strain "cured" for erythromycin resistance lacked the beta-plasmid. In the parent strain the beta-plasmid was estimated to be present to the extent of one to two copies per chromosomal genome equivalent whereas the alpha- and gamma-plasmids were about nine and five copies, respectively.     

Streptococcus faecalis sex pheromone (cAD1) response: evidence that the peptide inhibitor excreted by pAD1-containing cells may be plasmid determined

Streptococcus faecalis strains harboring the conjugative plasmid pAD1 excrete a small peptide, iAD1, which inhibits the sex pheromone cAD1. Studies making use of the host strain Streptococcus faecium 9790, which normally does not excrete peptide pheromones, suggest that iAD1 may be determined directly by pAD1.     

英国多克隐花植物保护区森林土壤和凋落叶特性及其与真菌的关系

报道了英国独特的真菌保护区里真菌的生态学和生物多样性,而该保护区内有关物种构成的数据自1994年就开始进行收集了。关于真菌的生态学相互关系以及它们在总的生态系统功能中的作用可以作为生物多样性数据的补充。5~8月期间,在8块覆盖着不同植被（山毛榉,桦树,桦栎山毛榉,禾本科植物）实验区里,研究了森林凋落叶和叶本层土壤的特性和构成,测量了细菌种群数量和真菌的生物量（针对麦角固醇而言）。用相关分析和分段回归建模方法,结合可通过并行研究采集到的原生动物和线虫数据,得到了一系列结果。这些结果强调了某些因素的复杂性,这些因素影响着森林土壤和森林凋落叶中真菌生物量空间可变性的时间动态。大多数的相互作用看起来是瞬时的,在解释环境观测记录时应该对这一点给予充分考虑。最后,解释了若干具体关系,给出了进一步研究的方向,讨论了对整个生态系统功能研究的必要性。