A rigorous method for evaluation of the 6D compliance of external fixators

External fixators are standard devices to stabilize bone fractures and their compliance aims at producing an interfragmentary motion that promotes rapid and successful healing. While evaluation of their axial compliance is a routine test, the quantification and interpretation of their full 6 × 6 compliance matrix is an extensive and delicate task. In this context, the objective of this study was to develop, validate and demonstrate the potential of a rigorous method to quantify their 6 × 6 compliance matrix. An experimental system was developed to apply six independent static forces and moments to an external fixator in the field of view of two infrared cameras quantifying the induced motion. The system was then tested with a calibration structure which compliance could be calculated analytically and numerically. Finally, the system was applied to compare three configurations of a commercial external wrist fixator. The results of the method proved to be reproducible and highly consistent with the linear elasticity theory in the physiological range of small deformations. A rigorous method for evaluation of the 6D compliance becomes therefore available for research in mechanobiology of fracture healing by external fixation.     

Suppression of ERK activation in urethral epithelial cells infected with Neisseria gonorrhoeae and its isogenic minD mutant contributes to anti-apoptosis

In gonococci-infected transduced human urethral epithelial cells (THUEC), the role of ERK, a mitogen-activated protein kinase (MAPK), in apoptosis is unknown. We observed lowering of ERK activation in THUEC following infection with anti-apoptosis-inducing Neisseria gonorrhoeae strain CH811. An isogenic cell division mutant of this strain, Ng CJSD1 (minD deficient), which is large and abnormally shaped, reduced ERK phosphorylation levels even more than its parental strain in THUEC. This led to higher anti-apoptosis in mutant-infected cells as compared to the parental strain-infected cells. Our results suggest that N. gonorrhoeae infection reduces ERK activation in THUEC contributing to anti-apoptosis.     

Raman microspectroscopy as an identification tool within the phylogenetically homogeneous 'Bacillus subtilis' group

Vibrational methods have multiple advantages compared to more classic, chemotaxonomic and even molecular microbial tools for the identification of bacteria. Nevertheless, their definite breakthrough in diagnostic microbiology laboratories is determined by their identification potential. This paper reports on the profound evaluation of Raman spectroscopy to identify closely related species by means of 68 Bacillus strains that are assigned or closely related to the phylogenetically homogeneous ‘Bacillus subtilis’-group (sensu stricto). These strains were chosen to represent biological variation within the selected species and to create a realistic view on the possibilities of this technique

The evaluation resulted in 49/54 correct identifications at the species level for intern and 15/19 for extern testing. The correct identification of strains, which were not represented in the training set, supports the potential as an identification tool within the ‘B. subtilis group’. Considering the vague borderline between the species studied, Raman spectroscopy can be regarded here as a promising application for identifications at the species level.     

Automatic classification within families of transposable elements: Application to the mariner Family

The higher levels of the classification of transposable elements (TEs) from Classes to Superfamilies or Families, is regularly updated, but the lower levels (below the Family) have received little investigation. In particular, this applies to the Families that include a large number of copies. In this article we propose an automatic classification of DNA sequences. This procedure is based on an aggregation process using a pairwise matrix of distances, allowing us to define several groups characterized by a sphere with a central sequence and a radius. This method was tested on the mariner Family, because this is probably one of the most extensively studied Families. Several Subfamilies had already been defined from phylogenetic analyses based on multiple alignments of complete or partial amino-acid sequences of the transposase. The classification obtained here from DNA sequences of 935 items matches the phylogenies of the transposase. The rate of error from a posteriori re-assignment is relatively low.     

Sperm velocity and its relation to social status in Arctic charr (Salvelinus alpinus)

Sperm velocity has been shown to be a major determinant of fertilization success of external fertilizers. Yet, sperm velocity varies both within and between ejaculates and only a small number of fast sperm cells within an ejaculate are likely to have the potential of fertilizing the eggs. Having such fast cells should be of special importance during sperm competition, particularly for subordinate males that may release their sperm later or further away from eggs, than dominants. We examined ejaculates of dominant and subordinate male Arctic charr (Salvelinus alpinus), a species with sperm competition. Yet, rather than examining just average sperm velocity values, the aim was to examine whether the fastest fraction of sperm cell from dominant and subordinate males differed in velocity. While there was no difference in the average sperm velocity between dominant and subordinate males, analysis of the fastest swimming sperm cells show that subordinate males have significantly higher initial sperm velocity than dominant males within the 10, 5 and 1% fastest sperm cells. That is, the difference in sperm velocity between dominant and subordinate charr is most predominant among the fastest sperm cells. In sum, this study emphasizes the importance of studying the fastest sperm cells in the ejaculates, as status-dependent differences in sperm velocity may not be detected using average values.     

The environmental impact of engineering education in Australia

Background, aim, and scope  The process of producing a graduate is a complex one involving major effort usually by large institutions such as universities. The Faculty of Engineering and Surveying at the University of Southern Queensland, Australia produces several hundred engineering and spatial science graduates each year using both on-campus and external modes of study. The purpose of this study is to determine the major causes of environmental impact in this process with a view to targeting areas where improvements may be made. Materials and methods  An inventory of all major inputs to and outputs from the faculty was compiled from a mixture of measurements, real data, and financial data for the calendar year 2006. Data for graduate output were also compiled. These data were then assessed using SimaPro software, mainly Australian data and predominantly the Eco-indicator 99 (E) method of impact assessment. Results  The analysis shows that environmental impacts are many and varied as might be expected from a complex operation like a university. However, energy inputs in the form of electricity from black coal, staff and student travel and the embodied impact of buildings were dominant. Discussion  The results obtained may point the way towards future consideration of areas where environmental impact might be reduced by changes in institution strategies such as the way external students are taught and the way the electricity usage in our buildings is managed. Conclusions  The environmental impact of undergraduate education is complex and involves many different areas of activity. However, the use of energy in various forms is of major significance in this impact. Recommendations and perspectives  It is recommended that university managers consider the results presented in this paper and use them as a starting point in developing strategies to reduce the impact of their institutions.     

De-novo modeling and ESR validation of a cyanobacterial FoF1-ATP synthase subunit bb′ left-handed coiled coil

The structure and functional role of the dimeric external stalk of F_oF₁-ATP synthases have been very actively researched over the last years. To understand the function, detailed knowledge of the structure and protein packing interactions in the dimer is required. In this paper we describe the application of structural prediction and molecular modeling approaches to elucidate the structural packing interaction of the cyanobacterial ATP synthase external stalk. In addition we present biophysical evidence derived from ESR spectroscopy and site directed spin labeling of stalk proteins that supports the proposed structural model. The use of the heterodimeric bb′ dimer from a cyanobacterial ATP synthase (Synechocystis sp. PCC 6803) allowed, by specific introduction of spin labels along each individual subunit, the evaluation of the overall tertiary structure of the subunits by calculating inter-spin distances. At defined positions in both b and b′ subunits, reporter groups were inserted to determine and confirm inter-subunit packing. The experiments showed that an approximately 100 residue long section of the cytoplasmic part of the bb′-dimer exists mostly as an elongated α-helix. The distant C-terminal end of the dimer, which is thought to interact with the δ-subunit, seemed to be disordered in experiments using soluble bb′ proteins. A left-handed coiled coil packing of the dimer suggested from structure prediction studies and shown to be feasible in molecular modeling experiments was used together with the measured inter-spin distances of the inserted reporter groups determined in ESR experiments to support the hypothesis that a significant portion of the bb′ structure exists as a left-handed coiled coil.     

新型可透X线骨外固定器的研制

目的治疗近关节骨折、复杂骨折、骨缺损及骨不连等的一种新型可透x线骨外固定器。方法由固定部件、连接杆、万向头、连接杆锁紧螺帽、骨折固定螺钉、固定螺钉锁紧螺帽构成,通过x线能够全方位地观察骨折情况,调整骨外固定器使骨折对位对线。结果可避免因传统金属骨外固定器对术后骨折愈合情况观察,固定安全可靠,特别适用于战时、紧急情况下对骨折的固定,固定不超关节,故可以术后即刻关节功能锻炼。结论固定器设计合理,构思新颖,值得推广应用。     

Comparison of neurolin (ALCAM) and neurolin-like cell adhesion molecule (NLCAM) expression in zebrafish

Many immunoglobulin (Ig)-superfamily cell adhesion molecules influence skeletal muscle formation. In Drosophila, dumbfounded (duf/kirre), irreC, sticks and stones and hibris encode related Ig-family proteins expressed in subsets of neurons and muscle precursor cells. The family mediates cell migration, axon guidance and fusion of myoblasts. Despite the importance of these genes in invertebrate myogenesis, no obvious functional parallels are known in vertebrate myogenesis. Here we investigate the gene expression pattern and phylogenetic and protein-structural relationships of the duf-related molecules neurolin and neurolin-like cell adhesion molecule (NLCAM), members of the activated leukocyte cell adhesion molecule (ALCAM) sub-family of Ig-molecules. These proteins are among the closest to Duf/Kirre by sequence. During zebrafish development, neurolin is expressed in subsets of somite and muscle cells, heart and numerous sites of neuronal maturation. The new ALCAM-family member, NLCAM, appears to have arisen by duplication of neurolin/ALCAM. NLCAM is expressed widely during gastrulation, particularly in the nascent neural plate, but later becomes predominantly expressed in sites of muscle and nerve maturation and in the fin fold. The expression of each gene is often in groups of cells in similar parts of the embryo; for example, in the region of Rohon Beard neurons, trigeminal ganglion and fusing fast and migrating slow muscle fibres. However, expression can also be distinct and dynamic; for example, muscle pioneer fibres express neurolin but not NLCAM at high level. Both molecules are expressed in subsets of muscle precursors at times prior to fusion.