Mercury and molt: no strong Hg trend across songbird primaries

Mercury (Hg) is a bioaccumulative metal that can threaten the health of wild birds. Feathers are commonly used biomonitoring tools for non-lethally estimating Hg exposure in birds because they contain stable Hg concentrations upon completion of feather growth, when blood flow to the feather has stopped. Despite the common use of feathers as indicators of avian exposure, little is known about how feather concentrations relate to internal tissue exposures. Songbird feather physiology and how factors such as molt may impact Hg sequestration into songbird feathers are particularly lacking. To understand sequestration of Hg into primary feathers, we examined patterns of Hg concentrations among the 9 primary feathers of individual birds where molt order was known. Hg concentrations in the left primary feathers from 30 salvaged individual specimens from families Turdidae and Passeridae (Catharus ustulatus, Ixoreus naevius, Turdus migratorius, Melospiza melodia, Zonotrichia atricapilla, Passerella iliaca, Pipilo maculatus, Junco hyemalis) were measured. Preliminary results indicated that a conclusive trend in Hg concentration with increasing primary feather number was lacking, with only small variation in Hg concentration among primary feathers. A mixed effects repeated measures test yielded a p value of 0.2700 with ppm as the fixed effect and bird i.d. as a random effect. Similar studies in seabird primaries have shown strong downward trends in Hg ppm with molt order. The lack of a trend in songbird primaries may be influenced by diet shifts during molt or changes in sequestration to other feather tracts and body tissues. Conclusions on Hg exposure in birds based on feathers must take time and location between feather growth and the feather sampling into consideration

You are Not Welcome: Social Exchanges between Female Spider Monkeys (Ateles geoffroyi)

Group living leads to competition for food between group members. Two types of intragroup food competition may occur: scramble competition, in which all group members use the same resource, such that feeding opportunities are equal for everyone; and contest competition, in which some group members monopolize resources through aggression and dominance. In species in which females disperse from the natal group and immigrate into other groups, immigrant females increase group size and thus possibly food competition. Under these circumstances, other females may use aggression to discourage new females from joining the group. We assessed the distribution of aggression, embraces, and kisses among female spider monkeys (Ateles geoffroyi) in relation to group tenure. We recorded social interactions during 1688 10-min focal animal samples on 11 females in Santa Rosa, Costa Rica. We found that aggression was rare between long-term resident females and aggression rates were not higher during feeding than in other contexts, suggesting there was little contest competition. Long-term residents and less recently immigrant females showed higher aggression rates toward the most recent immigrants than toward other females, especially during the first months after a female immigrated, which coincided with the dry season. We did not find similar patterns for embrace and kiss. These results suggest that other females target aggression toward the most recent immigrants to reduce scramble competition. This finding suggests that group tenure should be included in socioecological models for species with female dispersal. © 2017 Springer Science+Business Media, LL

The Epidemiology of Youth Sport-Related Shoulder Injuries: A Systematic Review

Background. Youth around the globe place their shoulders at risk for injury when participating in sports. Shoulder injuries may vary in severity, produce the potential for time-loss from sport, and result in functional disability. We sought to explore sport-related shoulder injuries in youth by identifying injury rates, risk factors, injury mechanisms, and injury prevention strategies. Methods. All relevant full-text articles were identified by searching MEDLINE, EMBASE, CINAHL, Sport Discus, and the Cochrane Controlled Trials Registry. No date restrictions were used. All full-text studies reporting original research describing sport-related shoulder injury among female and/or male youth from 5 to 18 years old were included. Results. Of 3,889 studies screened, 97 described shoulder injury in youth sports. Shoulder injuries were identified in 24 unique sports. The median seasonal prevalence of shoulder injury was 10.9% (range 1.2–28.2%). The most common injury mechanisms identified were contacted with another player, contact with the playing environment, and falling to the ground. Risk factors for shoulder injury identified were side-to-side strength imbalances, weak external rotator muscles, and scapular dyskinesia. One study evaluated a successful training strategy to prevent shoulder injuries, but two other interventions demonstrated no effect. Conclusions. Sport-related shoulder injuries are prevalent among youth athletes. Injury risk factors identified included modifiable intrinsic factors such as strength, range of motion, and training load. The most common injury mechanism was direct contact with either another person or an object in the playing environment. Innovative shoulder-specific strategies are needed to reduce shoulder injuries in this population. Trial Registration: PROSPERO ID: CRD42020189142.Peer Reviewe

A Randomized Trial of SMART Goal Enhanced Debriefing after Simulation to Promote Educational Actions

Introduction Goal setting is used in education to promote learning and performance. Debriefing after clinical scenario-based simulation is a well-established practice that provides learners a defined structure to review and improve performance. Our objective was to integrate formal learning goal generation, using the SMART framework (Specific, Measurable, Attainable, Realistic, and Time-bound), into standard debriefing processes (i.e., “SMART Goal Enhanced Debriefing”) and subsequently measure the impact on the development of learning goals and execution of educational actions. Methods This was a prospective multicenter randomized controlled study of 80 emergency medicine residents at three academic hospitals comparing the effectiveness of SMART Goal Enhanced Debriefing to a standard debriefing. Residents were block randomized on a rolling basis following a simulation case. SMART Goal Enhanced Debriefing included five minutes of formal instruction on the development of SMART learning goals during the summary/application phase of the debrief. Outcome measures included the number of recalled learning goals, self-reported executed educational actions, and quality of each learning goal and educational action after a two-week follow-up period. Results The mean number of reported learning goals was similar in the standard debriefing group (mean 2.05 goals, SD 1.13, n=37 residents), and in the SMART Goal Enhanced Debriefing group (mean 1.93, SD 0.96, n=43), with no difference in learning goal quality. Residents receiving SMART Goal Enhanced Debriefing completed more educational actions on average (Control group actions completed 0.97 (SD 0.87), SMART debrief group 1.44 (SD 1.03) p=0.03). Conclusion The number and quality of learning goals reported by residents was not improved as a result of SMART Goal Enhanced Debriefing. Residents did, however, execute more educational actions, which is consistent with the overarching intent of any educational intervention

A Randomized Trial of SMART Goal Enhanced Debriefing after Simulation to Promote Educational Actions

Introduction: Goal setting is used in education to promote learning and performance. Debriefing after clinical scenario-based simulation is a well-established practice that provides learners a defined structure to review and improve performance. Our objective was to integrate formal learning goal generation, using the SMART framework (Specific, Measurable, Attainable, Realistic, and Time-bound), into standard debriefing processes (i.e., “SMART Goal Enhanced Debriefing”) and subsequently measure the impact on the development of learning goals and execution of educational actions.Methods: This was a prospective multicenter randomized controlled study of 80 emergency medicine residents at three academic hospitals comparing the effectiveness of SMART Goal Enhanced Debriefing to a standard debriefing. Residents were block randomized on a rolling basis following a simulation case. SMART Goal Enhanced Debriefing included five minutes of formal instruction on the development of SMART learning goals during the summary/application phase of the debrief. Outcome measures included the number of recalled learning goals, self-reported executed educational actions, and quality of each learning goal and educational action after a two-week follow-up period.  Results: The mean number of reported learning goals was similar in the standard debriefing group (mean 2.05 goals, SD 1.13, n=37 residents), and in the SMART Goal Enhanced Debriefing group (mean 1.93, SD 0.96, n=43), with no difference in learning goal quality. Residents receiving SMART Goal Enhanced Debriefing completed more educational actions on average (Control group actions completed 0.97 (SD 0.87), SMART debrief group 1.44 (SD 1.03) p=0.03). Conclusion: The number and quality of learning goals reported by residents was not improved as a result of SMART Goal Enhanced Debriefing. Residents did, however, execute more educational actions, which is consistent with the overarching intent of any educational intervention

Pten disruption in osteo-progenitor cells increases marrow adipocyte density and size.

<p>(A) Tibias from 12-month old <i>Osx-Cre</i> (control), <i>Osx-Cre; Pten</i>^<i>fl/fl</i>, and <i>Osx-Cre; Rb1</i>^<i>fl/+</i>; <i>Pten</i>^<i>fl/fl</i>, were cut for H&E staining and proximal end displayed. Scale bars, 500 μM. Tibial marrow contents from 12-month old mice were compared using NIH ImageJ. (B) Percentage of marrow fat; (C) adipocyte number (#/mm²); (D) adipocyte size (μm²) were measured using histomorphometry. Data are the mean ± SD from six mice. *, <i>p</i> < 0.05; **, <i>p</i> < 0.01; ***, <i>p</i> < 0.005.</p

Disruption of the <i>Pten</i> gene in osteoblast precursors leads to increased calvaria thickness.

<p>(A) μCT analysis was performed on 12-month-old <i>Osx-Cre</i> (control) and <i>Osx-Cre; Pten</i>^<i>fl/fl</i> calvaria. (B) Representative coronal calvarial sections from 12-month old mice. Scale bar, 500 μM. (C) Bar graphs showing the calvarial thickness (mean ± SD; n = 6). ***, <i>p</i> < 0.005.</p

Pten and Rb co-deletion in osteoblast precursor cells causes rapid lipoma but not osteosarcoma tumor onset.

<p>(A) H&E staining of sections from lipoma tumors derived from <i>Osx-Cre; Rb1</i>^<i>fl/fl</i>; <i>Pten</i>^<i>fl/fl</i> mice. Scale bars, 200 μM (Left), 50 μM (Right). (B) Kaplan-Meier survival curve analysis for the indicated genotypes: <i>Osx-Cre</i> (n = 21), <i>Osx-Cre; Rb1</i>^<i>fl/fl</i>; <i>p107</i>^<i>-/-</i> (n = 37), <i>Osx-Cre; Pten</i>^<i>fl/fl</i> (n = 17), <i>Osx-Cre; Rb1</i>^<i>fl/+</i>; <i>Pten</i>^<i>fl/fl</i> (n = 43), and <i>Osx-Cre; Rb1</i>^<i>fl/fl</i>; <i>Pten</i>^<i>fl/fl</i> (n = 37). <i>p</i>-values were determined by log rank test comparing a genotype with that of the control mice. *, <i>p</i> < 0.05; **, <i>p</i> < 0.01; ***, <i>p</i> < 0.005; N.S., not significant.</p

Loss of <i>Pten</i> promotes primary calvaria cell differentaion into adipocytes and osteoblasts and is further accentuated by co-deletion of <i>Rb1</i>.

<p>(A) Primary calvarial osteoblasts were grown to confluence, infected with control or Adeno-Cre, and grown for 25 days with adipogenic differentiation media and measured for adipocyte differentiation by Oil red O staining. Scale bar: 50 μM. (B) Cells were cultured as in (A) but were treated with osteoblastic differentiation media. Terminal osteoblastic differentiation was measured by alizarin red staining. Results are representative of 6 experiments.</p

<i>Rb1</i> and <i>Pten</i> Co-Deletion in Osteoblast Precursor Cells Causes Rapid Lipoma Formation in Mice

<div><p>The <i>Rb</i> and <i>Pten</i> tumor suppressor genes are important regulators of bone development and both are frequently mutated in the bone cancer osteosarcoma (OS). To determine if <i>Rb1</i> and <i>Pten</i> synergize as tumor suppressor genes for osteosarcoma, we co-deleted them in osteoprogenitor cells. Surprisingly, we observed rapid development of adipogenic but not osteosarcoma tumors in the <i>ΔRb1/Pten</i> mice. <i>ΔPten</i> solo deleted mice also developed lipoma tumors but at a much reduced frequency and later onset than those co-deleted for <i>Rb1</i>. <i>Pten</i> deletion also led to a marked increase in adipocytes in the bone marrow. To better understand the function of <i>Pten</i> in bone development <i>in vivo</i>, we conditionally deleted <i>Pten</i> in OSX⁺ osteoprogenitor cells using <i>OSX-Cre</i> mice. μCT analysis revealed a significant thickening of the calvaria and an increase in trabeculae volume and number in the femur, consistent with increased bone formation in these mice. To determine if <i>Pten</i> and <i>Rb1</i> deletion actively promotes adipogenic differentiation, we isolated calvarial cells from <i>Pten</i>^<i>fl/fl</i> and <i>Pten</i>^<i>fl/fl</i>; <i>Rb1</i>^<i>fl/fl</i> mice, infected them with CRE or GFP expressing adenovirus, treated with differentiation media. We observed slightly increased adipogenic, and osteogenic differentiation in the <i>ΔPten</i> cells. Both phenotypes were greatly increased upon <i>Rb1/Pten</i> co-deletion. This was accompanied by an increase in expression of genes required for adipogenesis. These data indicate that <i>Pten</i> deletion in osteoblast precursors is sufficient to promote frequent adipogenic, but only rare osteogenic tumors. <i>Rb1</i> hetero- or homo-zygous co-deletion greatly increases the incidence and the rapidity of onset of adipogenic tumors, again, with only rare osteosarcoma tumors.</p></div