Background: The geometry of the tibial plateau is complex and asymmetric. Previous research has characterized

A combination of increased posterior-directed tibial plateau slope and shallow medial tibial plateau depth could be a major risk factor in anterior cruciate ligament injury susceptibility regardless of gender. Different injury risk models may be needed for men and women as other key risk factors are identified.

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Anterior cruciate ligament (ACL) injury continues to be at the forefront of sports injury concerns because of its impact on quality of life and joint health prognosis. One strategy is to reduce the occurrence of this injury by identifying at-risk subjects based on key putative risk factors. The purpose of our study was to develop models that predict the structural properties of a subject's ACL based on the combination of known risk factors. We hypothesized that the structural properties of the ACL can be predicted using a multi-linear regression model based on significant covariates that are associated with increased risk of injury, including age, sex, body size, and ACL size. We also hypothesized that ACL size is a significant contributor to the model. The developed models had predictive capabilities for the structural properties of the ACL: load at failure (R 2 = 0.914), elongation at failure (R 2 = 0.872), energy at failure (R 2 = 0.913), and linear stiffness (R 2 = 0.756). Furthermore, sex, age, body mass, BMI, and height were contributors (p < 0.05) to all predicted structural properties. ACL minimal area was a contributor to elongation, energy at failure, and linear stiffness (p < 0.05), but not to load at failure. ACL volume was also a contributor to elongation and energy at failure (p < 0.05), but not to linear stiffness and load at failure models. ACL length was not a significant contributor to any structural property. The clinical significance of this research is its potential, after continued development and refinement of the model, for application to prognostic studies that are designed to identify individuals at increased risk for injury to the ligament. Keywords: anterior cruciate ligament; structural properties; ACL size; body size; strength predictionThe high incidence of anterior cruciate ligament (ACL) injuries suffered by young active individuals, especially females, and the associated cost of treatment has been the subject of extensive research. [1][2][3][4] The negative impact of an ACL tear on a person's life is exacerbated by the increased risk of developing osteoarthritis (OA) when this injury is either treated with surgical reconstruction or conservatively through rehabilitation and activity modification. 5Recent research efforts have focused on determining the risk factors for ACL injury. Risk factor studies are crucial for developing intervention programs and for identifying who is at increased risk of suffering ACL injury so an intervention can be targeted at them. Such research has produced marked advances over the past decade.1 Although the question regarding sex-based disparity has not been answered, the susceptibility to ACL injury is universally believed to be multi-factorial, with complex interrelationships among key risk factors and separate risk models for males and females.1 Risk factors associated with increased risk of ACL injury include: footwear, surface type, subject sex, ACL geometry (size), femoral notch size, menstrual cycle phase, Q angle, tibial articular ...

The purpose of this study was to investigate the existence of sex-based differences in the ultrastructural characteristics of the human anterior cruciate ligament (ACL) as the underlying cause of differences in the structural and mechanical properties between sexes. The ACL of six male and six female cadaveric donors were randomly chosen from a pool of 10 male and 10 female ACLs that had previously been tested for their structural and mechanical properties. Eighteen tissue samples from the distal, proximal, and middle sections of the anteromedial and posterolateral bundles were analyzed by transmission electron microscopy. Female ACLs exhibited both lower fibril concentration and lower percent area occupied by collagen fibrils ( p < 0.05) compared to males. There was also a difference in the fibril diameters ( p < 0.05); donor age, height, body mass, and body mass index contributed significantly to this difference. In females, ACL stiffness and modulus of elasticity were highly correlated to fibril concentration (r ¼ 0.96 and 0.97, respectively); in males ACL failure load and strength were highly correlated to percent area occupied by collagen (r ¼ 0.96 and 0.96, respectively). These differences in ultrastructure may underlie differences in ACL properties between sexes. The anterior cruciate ligament (ACL) is a multifascicular structure made up of two bundles. Its two-bundle structure and complex attachment to the femur and the tibia allow for one or both bundles to be functional (taut) in all possible knee positions. 1 ACL bundles are composed of collagen fibrils oriented mostly in the direction of loading. 2 Strocchi et al. 3 and Baek et al. 4 previously described the ultrastructural characteristics of the human ACL, including size distribution of the collagen fibrils, number of fibrils per unit area, and percent area occupied by collagen, as determined by transmission electron microscopy (TEM). These investigators suggested that changes or variations in ultrastructural characteristics are strictly related to functional requirements. 4,5 Recent studies showed that ACL mechanical, structural, and geometric characteristics are dependent on sex. 6,12 Female ACLs offer less resistance to deformation (are less stiff) and fail at lower loads compared to male ACLs. Furthermore, molecular studies identified sex differences in expression of collagen and matrix metalloproteinase genes that influence remodeling and turnover of structural elements in the ACL. 7 If ACL properties indeed reflect ultrastructure, and sex-based differences in ACL properties exist, then the ultrastructure of the male and female ACL should also differ. To date, sex-based ultrastructural differences have not been reported. Furthermore, the mechanical properties of the ACL have not been directly linked to its ultrastructure.We hypothesized that collagen fibril measurements, including average fibril diameter, number of fibrils per unit area, and percent area occupied by collagen, are different between sexes. We further hypothesized that A...

In this study, a blend of polypropylene (PP) and two types of thermoplastic polyolefin elastomers (TPO) were prepared by melt mixing. The TPOs were either ethylene‐ or propylene‐based copolymer. The mechanical response and morphology of the blends were investigated using tensile and impact tests and scanning electron microscopy technique. There was significant increase in the impact strength of the TPO‐modified PP, which was an outcome of fine dispersion of TPO inclusions. In particular, the blends containing PP‐based TPO exhibited dramatic enhancement in toughness energy as featured by a plastic deformation in tensile test. The brittle‐tough transition had several deviations from theoretical models, in which generally the interparticle distance criterion was realized as a single parameter, only controlled the transition of brittle to tough behavior. Moreover, the brittle‐tough transition in tensile and impact mode tests was not coincident in the blend with a broad distribution of interparticle distance. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 44068.

Liposomal nanoparticles are the most commonly used drug nano-delivery platforms. However, recent reports show that certain pegylated liposomal nanoparticles (PLNs) and polymeric nanoparticles have the potential to enhance tumor growth and inhibit antitumor immunity in murine cancer models. We sought herein to identify the mechanisms and determine whether PLN-associated immunosuppression and tumor growth can be reversed using alendronate, an immune modulatory drug. By conducting in vivo and ex vivo experiments with the immunocompetent TC-1 murine tumor model, we found that macrophages were the primary cells that internalized PLN in the tumor microenvironment and that PLN-induced tumor growth was dependent on macrophages. Treatment with PLN increased immunosuppression as evidenced by increased expression of arginase-1 in CD11b+Gr1+ cells, diminished M1 functionality in macrophages, and globally suppressed T-cell cytokine production. Encapsulating alendronate in PLN reversed these effects on myeloid cells and shifted the profile of multi-cytokine producing T-cells towards an IFNγ+ perforin+ response, suggesting increased cytotoxic functionality. Importantly, we also found that PLN-encapsulated alendronate (PLN-alen), but not free alendronate, abrogated PLN-induced tumor growth and increased progression-free survival. In summary, we have identified a novel mechanism of PLN-induced tumor growth through macrophage polarization and immunosuppression that can be targeted and inactivated to improve the anticancer efficacy of PLN-delivered drugs. Importantly, we also determined that PLN-alen not only reversed protumoral effects of the PLN carrier, but also had moderate antitumor activity. Our findings strongly support the inclusion of immune-responsive tumor models and in-depth immune functional studies in the preclinical drug development paradigm for cancer nanomedicines, and the further development of chemo-immunotherapy strategies to co-deliver alendronate and chemotherapy for the treatment of cancer.

Interior-point methods for semidefinite optimization have been studied intensively, due to their polynomial complexity and practical efficiency. Recently, the second author designed an efficient primal-dual infeasible interior-point algorithm with full Newton steps for linear optimization problems. In this paper we extend the algorithm to semidefinite optimization. The algorithm constructs strictly feasible iterates for a sequence of perturbations of the given problem and its dual problem, close to their central paths. Two types of full-Newton steps are used, feasibility steps and (ordinary) centering steps, respectively. The algorithm starts from strictly feasible iterates of a perturbed pair, on its central path, and feasibility steps find strictly feasible iterates for the next perturbed pair. By using centering steps for the new perturbed pair, we obtain strictly feasible iterates close enough to the central path of the new perturbed pair. The starting point depends on a positive number ζ. The algorithm terminates in at most O n log n ε steps either by finding an ε-solution or by determining that the primal-dual problem pair has no optimal solution with vanishing duality gap satisfying a condition in terms of ζ.