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1.
Medial knee osteoarthritis is a debilitating disease. Surgical and conservative interventions are performed to manage its progression via reduction of load on the medial compartment or equivalently its surrogate measure, the external adduction moment. However, some studies have questioned a correlation between the medial load and adduction moment. Using a musculoskeletal model of the lower extremity driven by kinematics–kinetics of asymptomatic subjects at gait midstance, we aim here to quantify the relative effects of changes in the knee adduction angle versus changes in the adduction moment on the joint response and medial/lateral load partitioning. The reference adduction rotation of 1.6° is altered by ±1.5° to 3.1° and 0.1° or the knee reference adduction moment of 17 N m is varied by ±50% to 25.5 N m and 8.5 N m. Quadriceps, hamstrings and tibiofemoral contact forces substantially increased as adduction angle dropped and diminished as it increased. The medial/lateral ratio of contact forces slightly altered by changes in the adduction moment but a larger adduction rotation hugely increased this ratio from 8.8 to a 90 while in contrast a smaller adduction rotation yielded a more uniform distribution. If the aim in an intervention is to diminish the medial contact force and medial/lateral load ratio, a drop of 1.5° in adduction angle is much more effective (causing respectively 12% and 80% decreases) than a reduction of 50% in the adduction moment (causing respectively 4% and 13% decreases). Substantial role of changes in adduction angle is due to the associated alterations in joint nonlinear passive resistance. These findings explain the poor correlation between knee adduction moment and tibiofemoral compartment loading during gait suggesting that the internal load partitioning is dictated by the joint adduction angle. 相似文献
2.
The effect of specific proline residues on the kinetic stability of the triosephosphate isomerases of two trypanosomes 下载免费PDF全文
Valeria Guzmán‐Luna Andrea G. Quezada A. Jessica Díaz‐Salazar Nallely Cabrera Ruy Pérez‐Montfort Miguel Costas 《Proteins》2017,85(4):571-579
The effect of specific residues on the kinetic stability of two closely related triosephosphate isomerases (from Trypanosoma cruzi, TcTIM and Trypanosoma brucei, TbTIM) has been studied. Based on a comparison of their β‐turn occurrence, we engineered two chimerical enzymes where their super secondary β‐loop‐α motifs 2 ((βα)2) were swapped. Differential scanning calorimetry (DSC) experiments showed that the (βα)2 motif of TcTIM inserted into TbTIM (2Tc) increases the kinetic stability. On the other hand, the presence of the (βα)2 motif of TbTIM inserted into TcTIM (2Tb) gave a chimerical protein difficult to purify in soluble form and with a significantly reduced kinetic stability. The comparison of the contact maps of the (βα)2 of TbTIM and TcTIM showed differences in the contact pattern of residues 43 and 49. In TcTIM these residues are prolines, located at the N‐terminal of loop‐2 and the C‐terminal of α‐helix‐2. Twelve mutants were engineered involving residues 43 and 49 to study the effect over the unfolding activation energy barrier (EA). A systematic analysis of DSC data showed a large decrease on the EA of TcTIM (ΔEA ranging from 468 to 678 kJ/mol) when the single and double proline mutations are present. The relevance of Pro43 to the kinetic stability is also revealed by mutation S43P, which increased the free energy of the transition state of TbTIM by 17.7 kJ/mol. Overall, the results indicate that protein kinetic stability can be severely affected by punctual mutations, disturbing the complex network of interactions that, in concerted action, determine protein stability. Proteins 2017; 85:571–579. © 2016 Wiley Periodicals, Inc. 相似文献
3.
《Cell》2022,185(3):485-492.e10
4.
Felipe Vander Velden 《Anthrozo?s》2017,30(4):533-548
Narratives addressing the presence of European domestic dogs (Canis familiaris) in the encounters between Indians and non-Indians in the conquest of the Central and South American lowlands often portray those animals as terrible and bloodthirsty weapons. From the settlers’ perspective, dogs were formidable instruments in the subjugation of the native peoples they came across at various times over more than 500 years of American colonialization. But the indigenous narratives of these first contacts with dogs may exhibit distinct perspectives that view dogs not only as weapons, instruments, or tools of conquest but rather as agents or actors smoothing contact and establishing peaceful relations between Indians and non-Indians. This article explores the narratives of the first dogs encountered by two native populations in southwestern Brazilian Amazonia—the Puruborá and the Karitiana in the state of Rondônia—to demonstrate the canine agency behind the interethnic meetings in this region, where dogs were largely absent until the arrival of the Europeans and their descendants beginning in the sixteenth century. First contacts between Indians and non-Indians are complex inter-specific events, and may extend beyond only two participants (a group of non-Indians and a native people) to include at least three parties, since the actions and dispositions of dogs play a crucial role in the development of human interactions. Recollections of the first dogs encountered by the Puruborá and Karitiana point precisely toward recognizing the importance of the animal's presence as an actor, far beyond a mere instrument. 相似文献
5.
Building resource-conserving and environmental-friendly society (referred to as “two-oriented society”, TOS) is an important way proposed by the Chinese government to achieve sustainable development. In this paper, a pilot city of constructing TOS in China-Wuhan is taken as a case to evaluate the performance of TOS from 2005 to 2012. Treating the indicators of TOS as multi-dimensional vectors, this paper proposes a methodological framework by integrating the methods of vector angle and Euclidean distance to measure the angle and distance between the vector of annual status of TOS and the vector of planning target of TOS. Based on this, the paper employs coordination (the angle between the two vectors) and effectiveness (the distance between the two vectors) to describe the performance of TOS and its subsystems, including economic development (ED), social and people's well-being (SW), resource consumption (RC), resource recycling (RR), environmental quality (EQ) and pollution control (PC). Moreover, grey relational analysis approach is used to analyse the core factors influencing TOS construction. Results reveal that the performance of TOS in Wuhan is continually improved in the study period while the performance of its subsystems shows several differences: (1) both coordination and effectiveness of TOS, ED and SW keep on improving, while those of EQ fluctuate; (2) the effectiveness of both RR and PC shows a downward trend while the coordination of them fluctuates; (3) the actual value of RC indicators reaches the planning targets. Based on the analysis of determinants, we suggest that strengthening technological ability and adding investment are extremely important to improve the performance of RC and PC. For the sake of improving RR, it is critical to provide more government public expenditure and encourage financial institutions to provide more loans to stimulate and support the businesses. Moreover, increasing the amount of R&D funding and maintaining steady external economic environment are proved to be effective to improve all subsystems of TOS. 相似文献
6.
7.
The densities of adhesion of Staphylococcus epidermis, Staphylococcus aureus and Serratia marcescens to five types of plastics were studied in relation to interfacial free energies at the aqueous interfaces of both the bacteria and the plastics. The free energy of adhesion of bacteria to plastic in an aqueous medium is a linear function of partition of the bacteria between the solid surface and the liquid phase. These results show that the thermodynamics of the partitioning of a suspended particle between two immiscible liquid phases also apply to partitioning between a liquid and a solid phase. 相似文献
8.
Ryan C. Garrick John D. Banusiewicz Stephanie Burgess Chaz Hyseni Rebecca E. Symula 《Journal of Biogeography》2019,46(2):268-278
Secondary contact between long isolated populations has several possible outcomes. These include the strengthening of preexisting reproductive isolating mechanisms via reinforcement, the emergence of a hybrid lineage that is distinct from its extant parental lineages and which occupies a spatially restricted zone between them, or complete merging of two populations such that parental lineages are no longer extant (“lineage fusion” herein). The latter scenario has rarely been explicitly considered in single‐species and comparative phylogeographic studies, yet it has the potential to impact inferences about population history and levels of congruence. In this paper, we explore the idea that insights into past lineage fusion may now be possible, owing to the advent of next‐generation sequencing. Using simulated DNA sequence haplotype datasets (i.e., loci with alleles comprised of a set of linked nucleotide polymorphisms), we examined basic requirements (number of loci and individuals sampled) for identifying cases when a present‐day panmictic population is the product of lineage fusion, using an exemplar statistical framework—approximate Bayesian computation. We found that with approximately 100 phased haplotype loci (each 400 bp long) and modest sample sizes of individuals (10 per population), lineage fusion can be detected under rather challenging scenarios. This included some scenarios where reticulation was fully contained within a Last Glacial Maximum timeframe, provided that mixing was symmetrical, ancestral gene pools were moderately to deeply diverged, and the lag time between the fusion event and gene pool sampling was relatively short. However, the more realistic case of asymmetrical mixing is not prohibitive if additional genetic data (e.g., 400 loci) are available. Notwithstanding some simplifying assumptions of our simulations and the knowledge gaps that remain about the circumstances under which lineage fusion is potentially detectable, we suggest that the recent release from data limitation allows phylogeographers to expand the scope of inferences about long‐term population history. 相似文献
9.
The effect of axial ligand nodal plane orientation on the contact and pseudocontact shifts of a symmetrical low-spin octamethylferriheme
center has been calculated as a function of the angle of the axial ligand. Simple Hückel techniques have been used to estimate
the contact contribution, and values obtained from model hemes, together with counter-rotation of the g-tensor, have been used to estimate the pseudocontact contribution, for the eight β-pyrrole methyl and four meso-H positions. It is found that the maximum and minimum contact shifts occur when the axial ligand is aligned at an angle of
±15° to the meso-H axes of the heme, rather than when the axial ligand plane lies along the porphyrin nitrogens, as assumed previously by
some investigators. For systems having one planar axial ligand or two ligands in parallel planes, the contact and pseudocontact
contributions at the meso-H positions are comparable in size (at least on the basis of simple Hückel estimates), while the contact contribution clearly
dominates the isotropic shifts of the heme methyls. Allowing for the substituent effect of the 2,4-vinyls of protohemin, or
the 2,4-thioethers of hemin c, as well as the average diamagnetic shifts of the heme methyls and meso-H, plots of the predicted shifts as a function of axial ligand nodal plane orientation have been constructed for hemin b- and c-containing proteins. Excellent agreement in the order of shifts, and reasonable agreement in the sizes of the observed shifts,
is observed in the majority of the ferriheme proteins for which the methyl and meso-H resonances have been assigned and proton shifts reported. Plots have also been constructed for hemin c-containing proteins having the two axial ligand nodal planes oriented at relative angles of 40°, 70°, and 80°. Excellent
agreement in the order of shifts, and reasonable agreement in the magnitudes of the observed shifts, is observed in all cases
of bacterial cytochromes which do not fit the plots that assume the ligands are in parallel planes, except one – the cytochrome
c-552 of Nitrosomonas europae. Except for this case, where the order of the predicted methyl shifts at any angle of the axial ligands disagrees with the
observed, the reasons can usually be attributed to a large dihedral angle between two axial ligand nodal planes, to strong
H-bonding interactions involving His and/or CN– ligands, or to off-axis binding of one (or both) axial ligand(s). Ruffling of the porphyrin ring may also contribute to the
contact shift in as yet undefined ways. Hence, despite the simplicity of the calculations, the agreement with observed data
is highly satisfying and the concept of the importance of axial ligand plane orientation on the observed proton shifts of
heme proteins is fully confirmed.
Received: 15 June 1998 / Accepted: 6 August 1998 相似文献
10.