The geographic origin of old Douglas-fir stands growing in Central Europe

Since the nineteenth century, Douglas-fir seed sources have been widely used for establishment of forest stands outside its natural distribution range. In Europe, some of these old Douglas-fir stands are registered as seed stands and provide seed sources for nurseries, although it is unclear from which region in North America they originate. In recent years, the interest in planting Douglas-fir has increased substantially because the species is seen as a potential adaptation option to climate change. This makes the assignment of European Douglas-fir stands of unknown seed origin to their geographic origin in North America increasingly important, because the genetic quality of these plantations must be guaranteed. In this study, we use 13 nuSSR loci to investigate the origin of 67 Austrian and German Douglas-fir stands of unknown origin. We performed a hierarchical Bayesian cluster analysis using 38 native Douglas-fir populations. The resulting clusters are used as reference populations to assign the 67 Central European Douglas-fir stands from Austria and Germany planted more than 80 years ago. Our results suggest that the majority of our investigated Douglas-fir stands come from central Washington (USA), the recommended seed zones for Central Europe. Some stands were located outside the suggested area, e.g. central Oregon and Santa Fe (New Mexico). The accuracy assessment of our approach revealed the best performance for the highest hierarchical level, e.g. assigning populations either to the coastal or the Rocky Mountain variety. As expected, the uncertainty increases with decreasing hierarchical level. The final assessment, if an admixture of seed sources within the European Douglas-fir stands is evident suggests that 23 of the Douglas-fir stands show an admixture which was not detected in our Douglas-fir reference populations growing in the natural distribution range.     

Genetic diversity and adaptive traits of European versus American Douglas-fir seedlings

Due to its productivity and potential to adapt to the expected climate change, the Douglas-fir is one of the most important commercial non-native forest tree species in Europe. Currently, seeds from both non-native European and native American seed stands are used for plantations. In this study, we investigate European seed lots for their native origin (variety and potential geographic origin in America) and assess the adaptability, growth and survival potential of European versus American Douglas-fir seed lots. We compare the genetic diversity, morphological characteristics such as height (h), root collar diameter (rcd) and the ratio of h/rcd, and the timing of bud burst. We investigate 852 1-year-old seedlings from 10 different US and European seed lots representing 5 provenance regions which are sold in Germany and Austria. Seedlings are genotyped for 13 nuclear SSRs and analysed together with reference data set and standard genetic structuring and assignment methods. Adaptive traits of morphological characteristics and timing of bud burst of the seedlings are recorded and statistically analysed. The results show that the investigated European seedlings originate from recommended American native seed sources and represent both varieties and inter-varietal admixed individuals. European seedlings have a lower genetic diversity versus the American seedlings and native populations. They show significant differences in the adaptive traits such as morphological characteristics and timing of bud burst. According to the genetic diversity indices, certified North American Douglas-fir seed sources should be preferred for planting in Central Europe.     

Earthworm collection from agricultural fields: Comparisons of selected expellants in presence/absence of hand-sorting

The role earthworms play in soil fertility is under increasing scientific scrutiny, especially in light of the fact that farmers are seeking to reduce soil tillage. However, there are many discrepancies in earthworm sampling methods. The aim of this study is to compare the efficiency of three chemical expellants (formaldehyde, commercial ‘hot’ mustard and allyl isothiocyanate, abbreviated AITC), with two sampling methods: (i) a simple method that consisted in spreading an expellant solution on the soil and retrieving earthworms that emerged at the soil surface, and (ii) a combined method that consisted in applying a chemical to expel earthworms and then hand-sorting the remaining earthworms from the block of soil. Sampling efficiency was measured in terms of earthworm density and biomass, for endogeic and anecic earthworms.With the simple method, a higher density of earthworms was sampled using formaldehyde and AITC than with mustard. Formaldehyde, AITC and mustard expelled not significantly different biomasses of 47.7, 31.9 and 20.5 g m^?2, respectively, on average over the three plots. The combined method did not yield a significantly different density or biomass with the different chemicals.Formaldehyde is toxic and commercial ‘hot’ mustard is difficult to standardise and inefficient when used without hand-sorting. Accounting for the accuracy of the sampling methods as well as the toxicity of the chemicals to users and soil organisms, AITC appears to be a reliable and promising chemical expellant whether or not in combination with hand-sorting. Its use would be a step towards standardizing earthworm sampling methods.     

An in vitro biomechanical comparison of a limited-contact dynamic compression plate fixation with a dynamic compression plate fixation of osteotomized equine third metacarpal bones

OBJECTIVES: To compare the monotonic biomechanical properties and fatigue life of a broad, limited contact, dynamic compression plate (LC-DCP) fixation with a broad, dynamic compression plate (DCP) fixation to repair osteotomized equine 3rd metacarpal (MC3) bones. STUDY DESIGN: In vitro biomechanical testing of paired cadaveric equine MC3 with a mid-diaphyseal osteotomy, stabilized by 1 of 2 methods for fracture fixation. ANIMAL POPULATION: Twelve pairs of adult equine cadaveric MC3 bones. METHODS: Twelve pairs of equine MC3 were divided into 3 test groups (4 pairs each) for (1) 4-point bending single cycle to failure testing, (2) 4-point bending cyclic fatigue testing, and (3) torsional single cycle to failure testing. An LC-DCP (8-hole, 4.5 mm) was applied to the dorsal surface of 1 randomly selected bone from each pair. One DCP (8-hole, 4.5 mm broad) was applied dorsally to the contralateral bone from each pair. All plates and screws were applied using standard AO/ASIF techniques to MC3 bones that had mid-diaphyseal osteotomies. Mean test variable values for each method were compared using a paired t-test within each group. Significance was set at P<.05. RESULTS: The mean 4-point bending yield load, yield bending moment, composite rigidity, failure load, and failure bending moment of LC-DCP fixation were significantly greater (P<.01) than those of broad DCP fixation. Mean cycles to failure for 4-point bending was significantly (P<.001) greater for broad DCP fixation compared with broad LC-DCP fixation. Mean yield load, mean composite rigidity, and mean failure load in torsion was significantly (P<.02) greater for broad LC-DCP fixation compared with broad DCP fixation. CONCLUSION: Broad LC-DCP offers increased stability in static overload testing, however, it offers significantly less stability in cyclic fatigue testing. CLINICAL RELEVANCE: The clinical relevance of the cyclic fatigue data supports the conclusion that the broad DCP fixation is biomechanically superior to the broad LC-DCP fixation in osteotomized equine MC3 bones despite the results of the static overload testing.     

An in vitro evaluation of plate luting using osteotomized equine third metacarpal bones with a limited contact-dynamic compression plate

OBJECTIVES: To evaluate the effects of plate luting on the biomechanical properties of a broad limited contact-dynamic compression plate (LC-DCP) fixation to repair osteotomized equine 3rd metacarpal (MC3) bones. STUDY DESIGN: In vitro biomechanical testing of paired cadaveric equine MC3 with a mid-diaphyseal osteotomy, stabilized by LC-DCP fixation, with 1 of the pair luted with polymethylmethacrylate (PMMA). ANIMAL POPULATION: Ten pairs of adult equine cadaveric MC3 bones. METHODS: Ten pairs of equine MC3 were divided into 2 test groups (5 pairs each) for (1) palmarodorsal 4-point bending single cycle to failure testing and (2) palmarodorsal 4-point bending cyclic fatigue testing. The LC-DCP (8 hole, 4.5 mm) was applied to the dorsal surface of each pair of MC3 bones. All plates and screws were applied using standard AO/ASIF techniques. All MC3 bones had mid-diaphyseal osteotomies. One of the matched pairs of LC-DCP-MC3 constructs were randomly chosen to be luted with PMMA. Mean test variable values for each method were compared using a paired t-test within each group; significance was set at P<.05. RESULTS: Mean palmarodorsal 4-point bending yield bending moment, failure bending moment of the LC-DCP fixation with luting was not significantly different (P>.05) than those of the LC-DCP fixation without luting. Mean cycles to failure for palmarodorsal 4-point bending was significantly (P<.0003) greater, with a 7.2-fold increase, for the LC-DCP fixation with luting compared with the LC-DCP fixation without luting. CONCLUSION: Luting the broad LC-DCP with PMMA in the fixation osteotomized equine MC3 bones increases the fatigue life of cyclic loading for palmarodorsal 4-point bending under the in vitro conditions studied. CLINICAL RELEVANCE: The cyclic fatigue data supports the conclusion that luted broad LC-DCP fixation is biomechanically superior to the non-luted broad LC-DCP fixation in osteotomized equine MC3 bones.     

An in vitro biomechanical comparison of a prototype equine metacarpal dynamic compression plate fixation with double dynamic compression plate fixation of osteotomized equine third metacarpal bones

OBJECTIVES: To compare the monotonic biomechanical properties of a prototype equine third metacarpal dynamic compression plate (EM-DCP) fixation with a double broad dynamic compression plate (DCP) fixation to repair osteotomized equine third metacarpal (MC3) bones. STUDY DESIGN: In vitro biomechanical testing of paired cadaveric equine MC3 with a mid-diaphyseal osteotomy, stabilized by 1 of 2 methods for fracture fixation. POPULATION: Twelve pairs of adult equine cadaveric MC3 bones. METHODS: Twelve pairs of equine MC3 were divided into 3 test groups (4 pairs each) for (1) 4-point bending single cycle to failure testing, (2) 4-point bending cyclic fatigue testing, and (3) torsional testing. The EM-DCP (10-hole, 4.5 mm) was applied to the dorsal surface of one randomly selected bone from each pair. Two DCPs, 1 dorsally (10-hole, 4.5 mm broad) and 1 laterally (9-hole, 4.5 mm broad) were applied to the contralateral bone from each pair. All plates and screws were applied using standard AO/ASIF techniques to MC3 bones that had mid-diaphyseal osteotomies. Mean test variable values for each method were compared using a paired t-test within each group. Significance was set at P<.05. RESULTS: Mean 4-point bending yield load, yield bending moment, bending composite rigidity, failure load and failure bending moment of the EM-DCP fixation were significantly greater (P<.0001) than those of the double broad DCP fixation. Mean cycles to failure in 4-point bending of the EM-DCP fixation was significantly greater (P<.0008) than that of the double broad DCP fixation. Mean yield load, composite rigidity, and failure load in torsion of the EM-DCP fixation were significantly greater (P<.0035) than that of the double broad DCP fixation. CONCLUSION: The EM-DCP provides increased stability in both static overload testing and cyclic fatigue testing. CLINICAL RELEVANCE: Results of this in vitro study support the conclusion that the prototype EM-DCP fixation is biomechanically superior to the double broad DCP fixation for the stabilization of osteotomized equine MC3.     

Enterohaemorrhagic Escherichia coli: emerging issues on virulence and modes of transmission

Enterohaemorrhagic Escherichia coli (EHEC) constitute a subset of serotypes (E. coli O157 and some other serogroups) of Shiga toxin (Stx)-producing E. coli (STEC) firmly associated with severe human illnesses like bloody diarrhoea and haemolytic uraemic syndrome. Stx production is essential but not sufficient for EHEC virulence. Most strains are capable of colonising the intestinal mucosa of the host with the "attaching and effacing" mechanism, genetically governed by a large pathogenicity island (PAI) defined as the Locus of Enterocyte Effacement. Other virulence factors carried by mobile genetic elements like PAI and plasmids have been recently described, and their role in the pathogenic process has not been fully elucidated. EHEC are zoonotic pathogens. They rarely cause disease in animals, and ruminants are recognised as their main natural reservoir. Cattle are considered to be the most important source of human infections with EHEC O157, and the ecology of the organism in cattle farming has been extensively studied. The organism has also been reported in sheep, goats, water buffalos, and deer. Pigs and poultry are not considered to be a source of EHEC and the sporadic reports may derive from accidental exposure to ruminant dejections. The epidemiology of EHEC infections has remarkably changed during the past ten years and an increasing number of unusual food vehicles have been associated with human infections. New routes of transmission have emerged, like contact with animals during farm visits and a wide variety of environment-related exposures. As for other zoonotic agents, having animals and raw products that are free from EHEC is not possible in practice. However, their occurrence can be minimised by applying high standards of hygiene in all the steps of the food production chain.     

The use of oral endoscopy for detection of cheek teeth abnormalities in 300 horses

The main objective of this study was to evaluate an endoscopic examination protocol for routine dental examination in horses. The oral cavities of 300 standing, sedated horses were examined under field and hospital conditions with a rigid endoscope using a standardised technique that included examination of the occlusal, lingual (palatal) and buccal surfaces of all cheek teeth rows. The most common cheek teeth abnormalities detected were sharp enamel edges (present in 96.3% of horses), focal overgrowths (64.3%), fissure fractures (54.3%), diastemata (24.3%) and infundibular hypoplasia/caries (48.3%). Rigid endoscopy of the equine oral cavity was found to be a safe non-invasive diagnostic technique that appeared to be superior to clinical oral examination for detecting subtle cheek teeth changes.     

In vitro biomechanical comparison of locking compression plate fixation and limited-contact dynamic compression plate fixation of osteotomized equine third metacarpal bones

Objective— To compare monotonic biomechanical properties and fatigue life of a broad locking compression plate (LCP) fixation with a broad limited contact dynamic compression plate (LC‐DCP) fixation to repair osteotomized equine third metacarpal (MC3) bones. Study Design— In vitro biomechanical testing of paired cadaveric equine MC3 with a mid‐diaphyseal osteotomy, stabilized by 1 of 2 methods for fracture fixation. Animal Population— Cadaveric adult equine MC3 bones (n=12 pairs). Methods— MC3 were divided into 3 groups (4 pairs each) for: (1) 4‐point bending single cycle to failure testing; (2) 4‐point bending cyclic fatigue testing; and (3) torsional single cycle to failure testing. The 8‐hole, 4.5 mm LCP was applied to the dorsal surface of 1 randomly selected bone from each pair. One 8‐hole, 4.5 mm LC‐DCP) was applied dorsally to the contralateral bone from each pair. All plates and screws were applied using standard ASIF techniques. All MC3 bones had mid‐diaphyseal osteotomies. Mean test variable values for each method were compared using a paired t‐test within each group. Significance was set at P<.05. Results— Mean yield load, yield bending moment, composite rigidity, failure load and failure bending moment, under 4‐point bending, single cycle to failure, of the LCP fixation were significantly greater than those of the LC‐DCP fixation. Mean cycles to failure for 4‐point bending was significantly greater for the LCP fixation compared with LC‐DCP fixation. Mean yield load, mean composite rigidity, and mean failure load under torsional testing, single cycle to failure was significantly greater for the broad LCP fixation compared with the LC‐DCP fixation. Conclusion— The 4.5 mm LCP was superior to the 4.5 mm LC‐DCP in resisting the static overload forces (palmarodorsal 4‐point bending and torsional) and in resisting cyclic fatigue under palmarodorsal 4‐point bending. Clinical Relevance— The results of this in vitro study may provide information to aid in the selection of a biological plate for the repair of equine long bone fractures.