Background Chromium (Cr) and cobalt (Co) are the essential elements for producing metal implants, but might have potential health issues. The research on the correlation between metal implants and blood Cr and Co on a large population is still limited. Methods National Health and Nutrition Examination Survey (NHANES) is a program of studies designed to assess the health status of Americans began in the early 1960s. The study was based on the NHANES database from two data collection years (2015–2016 and 2017–2018). The exposure variable of this study was whether the participants had metal objects in the body or not. The outcome variables were blood concentrations of Cr and Co. Age, body mass index, sex, race/ethnicity, income to poverty ratio, tap water behavior, shellfish/fish/tuna/salmon eating habits, level of education, smoking behavior, marital status, blood hemoglobin, and data collection years were included as confounding variables. Results A total of 4412 participants, aged 40 years or older, were included in this analysis, consisting of the without metal objects group (n = 3150) and the metal objects group (n = 1262). Metal objects was positively correlated to the accumulation of blood Cr (β = 0.072, 95% CI: 0.043–0.102, p < 0.001) and blood Co (β = 0.079, 95% CI: 0.049–0.109, p < 0.001). However, the positive correlation of metal objects with blood Cr was only presented in women (β = 0.112, 95% CI: 0.074–0.151, p < 0.001), but not in men. Meanwhile, the positive relationship between metal objects and blood Cr/Co was not observed in the Asian subgroup. Conclusions Blood Cr and Co concentrations were statistically higher in people with metal objects, but with race and sex differences. Level of Evidence Level IV, cross-sectional study

BackgroundTraumatic impacts to the articular joint surface are known to lead to degeneration of the cartilage, as in post-traumatic osteoarthritis (PTOA). While animal-based systems have been instrumental in understanding pathogenic progression of PTOA, they have not served to develop effective treatments for the disease. The limited progress in the development of disease-modifying OA drugs (DMOADs) may be due to insufficient mechanistic understanding of human disease onset/progression that can, in part, be attributed to insufficient in vitro models for disease and therapeutic modeling. To overcome this insufficiency, we are testing hydrogel-based models using adult human mesenchymal stromal cells to examine the effects of traumatic impacts on human cell-based engineered cartilage constructs. We hypothesize that cells encapsulated within biomimetic scaffolds will respond to traumatic impacts in a manner congruent with early PTOA pathogenesis in animal models.MethodsEngineered cartilage constructs were fabricated by encapsulating adult human bone marrow-derived mesenchymal stem cells (hBM-MSCs) in a photocrosslinkable, biomimetic hydrogel (15% methacrylated gelatin, GelMA) that were chondrogenically differentiated for 28 days using TGF-b3. Constructs were subjected to traumatic impacts with different strains or 10 ng/ml IL-1b. Cell viability and metabolism, mechanical property, gene expression, matrix protein production and activation of catabolic enzymes were assessed.ResultsLive and dead staining results showed that traumatic impacts of 30% strain caused massive cell death in engineered cartilage constructs. Elastic modulus of engineered cartilage constructs decreased significantly after traumatic impacts. CCK8 assay results also showed significant cell death and metabolism decrease in the constructs. GAG production decreased 1 day after impacts but recovered 7 days after impact, as was also observed in safranin O staining and GAG assay. RT-PCR results and IHC results showed that anabolic activities were depressed and catabolic enzymes (MMP13, ADAMTS4, ADAMTS5) were activated after impact. ConclusionTraumatic impacts delivered to engineered cartilage constructs induced PTOA-like changes in the encapsulated cells. The development of this in vitro PTOA model will contribute to development of DMOADs in the future.

Tumoral calcinosis, first termed by Inclan et al., 1 is a rare condition characterized by massive metastatic calcification around joints, which presents as single or multiple superficial or deep hard caseous nodules located periarticularly. The common symptoms of tumoral calcinosis are joint stiffness, joint functional impairment, and neurovascular compression. In the present case, the nodules were situated around the shoulder and wrist with no other symptoms. In particular, we, for the first time, report calcium oxalate crystal imaging in the mass via polarized microscopy.

Background: The “Stop The Bleed” (STB) campaign has achieved remarkable results since it launched in 2016, but there is no report on the application of a STB course combined with a trauma patient simulator. This study proposes the “problem-, team-, and evidence-based learning” (PTEBL) teaching method combined with Caesar (trauma patient simulator) based on the STB course, and compares its effect with the traditional teaching method in outstanding doctoral candidates training of hemostasis skills.Method: Seventy-eight outstanding doctoral candidates program students (five-years and eight-years) were selected as the research subjects and were randomly divided into a control group (traditional teaching method, n=34) and an experimental group (PTEBL teaching method combined with Caesar, n=44). Their confidence of hemostasis skills and willingness to rescue were investigated before and after the course in both groups.Result: Students’ self-confidence of STB skills and willingness to rescue in both groups were improved after the class. Compared with the control group, students in the experimental group were more confident in compressing with bandages and compressing with a tourniquet after a class (compressing with bandages: control group 3.9±0.8 vs. experimental group 4.3±0.7, P=0.014; compressing with a tourniquet: control group 3.9±0.4 vs. experimental group 4.5±0.8, P=0.001) More students in the experimental group than the control group thought that the use of Caesar for scenario simulation could improve learning (control group 55.9% vs. experimental group 81.8%, P=0.024), and showed higher teacher-student interaction (control group 85.3% vs. experimental group 97.7%, P=0.042) The overall effectiveness of the teaching was better in the experimental group than the control group (control group 85.3% vs. experimental group 97.7%, P=0.042). There was a significant positive correlation between teacher-students interaction and overall effectiveness of teaching (R=1.000; 95%CI, 1.000-1.000; P<0.001).Conclusion: The PTEBL teaching method combined with Caesar can effectively improve students' mastery of STB skills, and overcome the shortcomings of traditional teaching methods, which has a certain promotional value in the training of outstanding doctoral candidates in STB skills.