We sought to define "at risk" loading conditions associated with rotating-platform total knee arthroplasty (TKA-RP) implants that predispose to insert subluxation and spinout and to quantify ...tolerances for flexion-extension gap asymmetry and laxity in order to prevent these adverse events.
Biomechanical testing was performed on 6 fresh-frozen cadaveric limbs with a TKA-RP implant with use of a gap-balancing technique, followed by sequential femoral component revision with variable-thickness polyethylene inserts to systematically represent 5 flexion-extension mismatch and asymmetry conditions. Each configuration was subjected to mechanical loading at 0°, 30°, and 60°. Rotational displacement of the insert on the tibial baseplate, lateral compartment separation, and insert concavity depth were measured with use of a digital caliper. Yield torque, a surrogate for ease of insert rotation and escape of the femoral component, was calculated with use of custom MATLAB code.
Design-intended insert rotation decreased with increasing knee flexion angles in each loading configuration. Likewise, yield torque increased with increasing joint flexion and decreased with increasing joint laxity in all testing configurations. Insert instability and femoral condyle displacement were reproduced in positions of increasing knee flexion and asymmetrical flexion gap laxity. The depth of lateral polyethylene insert concavity determined femoral condylar capture and defined a narrow tolerance of <2 mm in the smallest implant sizes for flexion gap asymmetry leading to rotational insert instability.
Decreased femoral-tibial articular surface conformity with increasing knee flexion and asymmetrical flexion gap laxity enable paradoxical motion of the femoral component on the upper insert surface rather than the undersurface, as designed.
Mobile-bearing TKA-RP is a technically demanding procedure requiring a snug symmetrical flexion gap. As little as 2 mm of asymmetrical lateral flexion laxity can result in decreased conformity, condyle liftoff, and insert subluxation. Flexion beyond 30° decreases bearing surface contact area and predisposes to reduced insert rotation and mechanical malfunction.
The occurrence of bullying, victimization, and aggressive
victimization was documented in a sample of 5th graders. Bullies
comprised about 14% of the sample, whereas aggressive victims
and victims ...comprised, respectively, 5% and 18%.
Bullying and aggressive victimization was positively related to
youngsters' emotionality and activity and negatively related to peer
popularity. Although proactive and reactive aggression was related
to bullying scores within the group of bullies, only proactive
aggression was related to within-group popularity for bullies.
Having friends and being liked by one's peers were protective
factors against victimization, although the latter was more powerful
than the former. Suggestions for future research, school policy, and
intervention are made.
The relationship between the tissue injury healing response and development of heterotopic ossification (HO) is poorly understood. Here we compare a rat blast model and human traumatized muscle from ...a blast injury to study the early signatures of osteogenesis and fibrosis during the formation of HO.
Rat and human tissues were characterized using histology, scanning electron microscopy, immunohistochemistry, as well as gene and protein expression analysis. Additionally, animals and humans were assessed radiographically for HO formation following injury.
Markers of bone formation were dramatically increased in tissue samples from both humans and rats, and both displayed increased fibroproliferative regions within the injured tissues and elevated expression of markers of tissue fibrosis such as TGF-β1, Fibronectin, SMAD3 and PAI-1. Markers of inflammation and fibrosis (ACTA, TNFα, BMP1 and BMP3) were elevated at the RNA level in both rat and human samples. By day 42, bone formation in the rat blast model appeared similar in radiographs compared to human patients who progressed to develop post-traumatic HO.
Our data demonstrates that a similar early fibrotic response is evident in both the rat blast model and the human tissues following a traumatic injury and demonstrates the relevance of this animal model for future translational studies.
International food transit is a risk to public and animal health when not subject to legal importation sanitation procedures. Due to the extensive border area, illegal food import in Brazil is a ...common practice, especially in Rio Grande do Sul (RS), a state that borders with Argentina and Uruguay. The objective of this study was to evaluate the profile of Brazilians living in cities in RS that border with Argentina (BR-AR) or Uruguay (BR-UR) regarding the practice of illegal import of products of animal origin and to determine associations between the population characteristics and illegal import. A questionnaire with information related to the personal profile, habits of acquisition of imported food, and knowledge of health risks deriving from the consumption of the imported products was elaborated. The questionnaire was administered in six cities in RS (three cities bordering Argentina and three cities bordering Uruguay) and responses were obtained from 744 individuals. The variables city, sex, level of education, and knowledge were subjected to the chi-square test to verify the association between these variables and food import. Part of the interviewees admitted to illegally importing products of animal origin at both BR-AR (65.17%) and BR-UR (76.28%) borders. Dairy products were the main imported goods, followed by raw and processed meat. The study revealed that illegal import is common at the frontier region of RS, especially that of products of animal origin, dairy, and raw and processed meat. Although illegal importation occurs at all the cities under study, it was higher at the BR-UR border. Also, knowledge of the health risks influences the decision to import food or not.
Evolutionary developmental psychology involves the expression of evolved, epigenetic programs, as described by the developmental systems approach, over the course of ontogeny. There have been ...different selection pressures on organisms at different times in ontogeny, and some characteristics of infants and children were selected in evolution to serve an adaptive function at that time in their life history rather than to prepare individuals for later adulthood. Examples of such adaptive functions of immaturity are provided from infancy, play, and cognitive development. Most evolved psychological mechanisms are proposed to be domain specific in nature and have been identified for various aspects of children's cognitive and social development, most notably for the acquisition of language and for theory of mind. Differences in the quality and quantity of parental investment affect children's development and influence their subsequent reproductive and childcare strategies. Some sex differences observed in childhood, particularly as expressed during play, are seen as antecedents and preparations for adult sex differences. Because evolved mechanisms were adaptive to ancestral environments, they are not always adaptive for contemporary people, and this mismatch of evolved mechanisms with modern environments is seen in children's maladjustment to some aspects of formal schooling. We argue that an evolutionary perspective can be valuable for developing a better understanding of human ontogeny in contemporary society and that a developmental perspective is important for a better understanding of evolutionary psychology.
Abstract The cartilage endplate (CEP) is implicated as the main pathway of nutrient supply to the healthy human intervertebral disc (IVD). In this study, the diffusivities of nutrient/metabolite ...solutes in healthy CEP were assessed, and further correlated with tissue biochemical composition and structure. The CEPs from non-degenerated human IVD were divided into four regions: central, lateral, anterior, and posterior. The diffusivities of glucose and lactate were measured with a custom diffusion cell apparatus under 0%, 10%, and 20% compressive strains. Biochemical assays were conducted to quantify the water and glycosaminoglycan (GAG) contents. The Safranin-O and Ehrlich׳s hematoxylin and eosin staining and scanning electron microscopy (SEM) were performed to reveal the tissue structure of the CEP. Average diffusivities of glucose and lactate in healthy CEP were 2.68±0.93×10−7 cm2 /s and 4.52±1.47×10−7 cm2 /s, respectively. Solute diffusivities were region-dependent ( p <0.0001) with the highest values in the central region, and mechanical strains impeded solute diffusion in the CEP ( p <0.0001). The solute diffusivities were significantly correlated with the tissue porosities (glucose: p <0.0001, r =0.581; lactate: p <0.0001, r =0.534). Histological and SEM studies further revealed that the collagen fibers in healthy CEP are more compacted than those in the nucleus pulposus (NP) and annulus fibrosus (AF) and show no clear orientation. Compared to human AF and NP, much smaller solute diffusivities in human CEP suggested that it acts as a gateway for solute diffusion through the disc, maintaining the balance of nutritional environment in healthy human disc under mechanical loading and preventing the progression of disc degeneration.
A call by the Institute of Medicine to advance the cause of patient safety catalyzed the current focus on duty hours limits during resident education. Unrelated benefits to resident education have ...accrued from those efforts, but, despite rigorous study of the issue, there is little evidence of a positive impact on patient safety resulting from trainee duty hours adjustments. Moreover, the discussion has become worrisomely myopic in its singular preoccupation with the impact of postgraduate medical education duty hours on safe patient care. The author argues that patient safety efforts should focus instead on the three essential elements of capacity, of which a discussion of duty hours and fatigue are an important part, commitment, and competence. Commitment requires altruism and professionalism, which are discouraged by a shift-work orientation. Competence is essential for safe patient care; as duty hours are constricted in the name of reducing fatigue-related medical error, it must be remembered that a certain amount of time is required to both acquire a knowledge base and attain proficiency in needed technical skills. Until a competency-based educational system can be implemented, the profession and patients would be well served by a heightened awareness of the increased number of years required in a constrained work hours environment to achieve proficiency in the independent practice of medicine, especially when procedural competence is required. Such a realization will inevitably result in voluntary lengthening of some residency training programs, particularly in surgical disciplines and those medical specialties with a prominent procedural component.
The intent of this longitudinal, multi-method, multi-agent study was to examine changes in bullying, victimization, and aggressive victimization as well as changes in peer affiliation as youngsters ...made the transition from primary school through the first year of middle school. Results indicated that bullying and aggressive victimization were relatively stable across time, possibly due to temperamental factors. Changes in peer affiliation indicated that youngsters' casual contacts with peers initially decreased from primary to the beginning of middle school but recovered by the end of the year. Close relationships, however, decreased, and number of youngsters nominated as isolates increased. Being embedded in an affiliative network of peers, in turn, inhibited victimization. School environmental factors did not make significant contributions to bullying or victimization. Results are discussed in terms of the importance of social affiliations in minimizing victimization in early adolescence. Limitations of the research were noted and suggestions for future research were also made.
•Acartia tonsa copepod is more sensitive to NiCl2 than to nickel nanoparticles.•At the tested concentration egg production was not affected by both form of nickel.•Egg viability is the most sensitive ...end-point for both form of nickel.•Nickel dissolved in seawater increased with nanoparticle concentration.•Acartia tonsa adults were able to ingest nanoparticles.
Nickel compounds are widely used in industries and have been massively introduced in the environment in different chemical forms. Here we report the effect of two different chemical forms of nickel, NiCl2 and nickel nanoparticles (NiNPs), on the reproduction of the marine calanoid copepod Acartia tonsa. The behavior of nickel nanoparticles was analyzed with different techniques and with two protocols. In the “sonicated experiment” (SON) NiNP solution was sonicated while in the “non-sonicated experiment” (NON-SON) the solution was vigorously shaken by hand. Final nominal concentrations of 5, 10 and 50mgL−1 and 1, 5 and 10mgL−1 NiNPs were used for the acute and semichronic tests, respectively. Nanoparticle size did not change over time except for the highest concentration of 50mgL−1 NiNPs, in which the diameter increased up to 843nm after 48h. The concentration of Ni dissolved in the water increased with NP concentration and was similar for SON and NON-SON solutions. Our results indicate that sonication does not modify toxicity for the copepod A. tonsa. Mean EC50 values were similar for NON-SON (20.2mgL−1) and SON experiments (22.14mgL−1) in the acute test. Similarly, no differences occurred between the two different protocols in the semichronic test, with an EC50 of 7.45mgL−1 and 6.97mgL−1 for NON-SON and SON experiments, respectively. Acute and semichronic tests, conducted exposing A. tonsa embryos to NiCl2 concentrations from 0.025 to 0.63mgL−1, showed EC50 of 0.164 and 0.039mgL−1, respectively. Overall, A. tonsa is more sensitive to NiCl2 than NiNPs with EC50 being one order of magnitude higher for NiNPs. Finally, we exposed adult copepods for 4 days to NiCl2 and NiNPs (chronic exposure) to study the effect on fecundity in terms of daily egg production and naupliar viability. Egg production is not affected by either form of nickel, whereas egg viability is significantly reduced by 0.025mgL−1 NiCl2 and by 8.5mgL−1 NiNPs. At NiNP concentration below the acute EC50 (17mgL−1) only 9% of embryos hatched after 4 days. Interestingly, the percentage of naupliar mortality (>82%) observed in the semichronic test at the nominal concentration of 10mgL−1 NiNPs corresponding to almost 0.10mgL−1 of dissolved Ni, was similar to that recorded at the same Ni salt concentration. Electron microscopical analyses revealed that A. tonsa adults ingest NiNPs and excrete them through fecal pellets. To the best of our knowledge, this is the first study investigating the toxicity of two different forms of Ni on the reproductive physiology of the copepod A. tonsa and showing the ability of the calanoid copepod to ingest nanoparticles from seawater.
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