Relationships Between Common Preseason Screening Measures and Dance-Related Injuries in Preprofessional Ballet Dancers.

OBJECTIVE: To examine modifiable and nonmodifiable factors for associations with dance-related injury among preprofessional ballet dancers over 5 academic years. DESIGN: Prospective cohort study. METHODS: Full-time preprofessional ballet dancers (n = 452; 399 female; median age [range], 15 years [11-21]) participated across 5 academic years at a vocational school. Participants completed baseline screening and online weekly injury questionnaires including dance exposure (hours/week). Zero-inflated Poisson regression models were used to examine associations between potential risk factors measured at baseline and self-reported dance-related injury. RESULTS: In count model coefficients, left one leg standing score (log coefficient estimate, -0.249 [95% CI: -0.478, -0.02]; P = .033) and right unipedal dynamic balance time (log coefficient estimate, -0.0294 [95% CI: -0.048, -0.01]; P>.001) carried a protective effect with increased years of training when adjusted for Athletic Coping Skills Inventory (ACSI) score. A significant association was found for left unipedal dynamic balance time and dance-related injury (log coefficient estimate, 0.013 [95% CI: 0.000, 0.026]; P = .045) when adjusted for years of training and ACSI score. There were no significant associations between dance-related injury and ankle and hip range of motion, active straight leg raise, or Y Balance Test measures. CONCLUSION: When adjusted for years of previous dance training and psychological coping skills, there was a significant association between limb-specific lumbopelvic control and dynamic balance tasks, as well as self-reported dance-related injury in preprofessional ballet. J Orthop Sports Phys Ther 2023;53(11):703-711. Epub 3 October 2023. doi:10.2519/jospt.2023.11835.

Society for the History of Psychology: News and notes.

In this News and Notes column, information about eligibility and how to apply for The David B. Baker Fellowship in the History of Psychology--which supports student research at the Archives of the History of American Psychology--is provided; recent publications and presentations are noted; and P. Croce, Stetson University, briefly describes their visit to Greece and shares a photo of Cheiron, an ancient Greek god. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Addendum.

In the last issue of this journal, Ben Harris authored a research note on Margaret Floy Washburn and her cats (see record 2023-67784-001). What was not included with that piece was an image Washburn's bookplate, which shows an image of a cat (quite possibly a likeness of her most acclaimed cat, "Hiram") with an accompanying Biblical verse in Greek, taken from 1 Thessalonians 5:21, which translated reads as "Test all things; hold fast what is good (NKJV)." It is reproduced in this article. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Are Self-Reported and Parent-Reported Attention Problems and Hyperactivity Associated With Higher Rates of Concussion in Youth Ice Hockey Players?

OBJECTIVE: To examine the association between self-reported and parent-reported attention problems and hyperactivity and rates of injury and concussion in Canadian youth ice hockey players. DESIGN: Secondary analyses of 2 prospective cohort studies. SETTING: Canadian youth ice hockey teams. PARTICIPANTS: Ice hockey players (ages 11-17 years) were recruited by team, over 4 seasons (2011-2016). A combined 1709 players contributing 1996 player-seasons were analyzed (257 players participated in more than one season). ASSESSMENT OF RISK FACTORS: Data were collected from preseason baseline questionnaires, including child and parent proxy forms of the Behavior Assessment System for Children, second edition. MAIN OUTCOME MEASURES: Injury and concussion rates and incidence rate ratios (IRR) comparing players with and without self-identified or parent-identified attention problems and hyperactivity, adjusted for covariates (ie, body checking policy, previous injury/concussion, and age) and a random effect for team, were estimated using multiple multilevel negative binomial regression. RESULTS: When analyzed continuously, rates of concussion increased with higher self-reported and parent-reported measures of attention problems [IRR SELF = 1.025; 95% confidence interval (CI): 1.011-1.040; IRR PARENT = 1.032; 95% CI: 1.008-1.057]. Self-reported hyperactivity was significantly associated with concussion (IRR = 1.021; 95% CI: 1.007-1.035), but parent-reported hyperactivity was not (IRR = 1.005; 95% CI: 0.983-1.028). A T score ≥ 60 cutoff combining attention problems and hyperactivity scores (an estimate of probable attention-deficit hyperactivity disorder) was not significantly associated with rates of injury or concussion. CONCLUSIONS: Attention problems and hyperactivity may place youth ice hockey players at increased risk of concussion and injury. Preseason assessments could identify players for targeted concussion education and risk reduction strategies.

Saliva Cortisol as a Biomarker of Injury in Youth Sport-Related Concussion.

Increasing rates of sport-related concussion (SRC) in youth impose a significant burden on public health systems and the lives of young athletes. Accurate prediction for those likely to develop persistent post-concussion symptomology (PPCS) using a fluid biomarker, reflecting both acute injury and recovery processes, would provide the opportunity for early intervention. Cortisol, a stress hormone released through the hypothalamic-pituitary-adrenal (HPA) axis following injury, may provide a missing physiological link to clinical recovery. This cohort study investigated the change in saliva cortisol following SRC and the association between cortisol and symptom burden in pediatric ice hockey players. Further, the association between cortisol levels and medical clearance to return to play was explored. In total, cortisol samples from 233 players were included; 165 athletes (23.6% female) provided pre-injury saliva and 68 athletes (19.1% female) provided post-SRC saliva samples for cortisol analysis. Quantile (median) regressions were used to compare cortisol between pre-injury and post-SRC groups, and the association between total symptoms (/22) and symptom severity scores (/132) reported on the Sport Concussion Assessment Tool (SCAT)3/SCAT5 and post-SRC cortisol (adjusting for age, sex, history of concussion, and time from injury to sample collection). Results demonstrated significantly lower saliva cortisol in post-SRC athletes compared with the pre-injury group (ß = -0.62, 95% confidence interval [CI; -1.08, -0.16], p = 0.009). Post-SRC cortisol was not significantly associated with the SCAT3/SCAT5 symptom totals or symptom severity scores; however, females were found to report more symptoms (ß = 6.95, 95% CI [0.35, 13.55], p = 0.040) and greater symptom severity (ß = 23.87, 95% CI [9.58, 38.15], p = 0.002) compared with males. Exploratory time-to-event analysis revealed a point estimate suggesting a potential association between low cortisol levels and days to medical clearance to return to play. Although preliminary, these findings suggest that the HPA axis may be dysregulated post-SRC. Further, our exploratory analysis and case presentation of post-injury outliers highlight the need to further research cortisol as a prognostic biomarker to inform individualized sex-specific care after SRC.

Society for the History of Psychology news and notes.

Cheiron's Book Prize Committee is pleased to announce that the recipient of the 2022 Prize is Nadine Weidman, Lecturer on the History of Science at Harvard University, for her book Killer Instinct: The Popular Science of Human Nature in Twentieth-Century America. In other news from the Society for the History of Psychology, Marjorie Lorch has recently published an article on how the concept of a matched control group was initially developed in neuropsychological testing. Lorch, M. P. (2022). Defining 'normal': Methodological issues in Aphasia and intelligence research. Cortex, 153, 224-234. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

Bodychecking experience and rates of injury among ice hockey players aged 15-17 years.

BACKGROUND: Although high rates of injury occur in youth ice hockey, disagreements exist about the risks and benefits of permitting bodychecking. We sought to evaluate associations between experience with bodychecking and rates of injury and concussion among ice hockey players aged 15-17 years. METHODS: We obtained data from a prospective cohort study of ice hockey players aged 15-17 years in Alberta who played in leagues that permitted bodychecking. We collected data over 3 seasons of play (2015/16-2017/18). We compared players based on experience with bodychecking (≤ 2 v. ≥ 3 yr), estimated using local and national bodychecking policy and region of play. We used validated methodology of ice hockey injury surveillance to identify all injuries related to ice hockey games and defined concussions according to the Consensus Statement on Concussion in Sport. RESULTS: We included 941 players who contributed to 1168 player-seasons, with 205 players participating in more than 1 season. Compared with players with 2 years or less of bodychecking experience, those with 3 or more years of experience had higher rates of all injury (adjusted incidence rate ratio [IRR] 2.55, 95% confidence interval [CI] 1.57-4.14), injury with more than 7 days of time loss (adjusted IRR 2.65, 95% CI 1.50-4.68) and concussion (adjusted IRR 2.69, 95% CI 1.34-5.42). INTERPRETATION: Among ice hockey players aged 15-17 years who participated in leagues permitting bodychecking, more experience with bodychecking did not protect against injury. This provides further support for removing bodychecking from youth ice hockey.

Society for the History of Psychology news and notes.

Article presents 2021 Society for the History of Psychology award winners. (PsycInfo Database Record (c) 2022 APA, all rights reserved).

No association found between body checking experience and injury or concussion rates in adolescent ice hockey players.

OBJECTIVES: To compare rates of injury and concussion among U-15 (ages 13-14 years) ice hockey players playing in leagues allowing body checking, but who have a varying number of years of body checking experience. METHODS: This 5-year longitudinal cohort included U-15 ice hockey players playing in leagues where policy allowed body checking. Years of body checking experience were classified based on national/local body checking policy. All ice hockey game-related injuries were identified using a validated injury surveillance methodology. Players with a suspected concussion were referred to a study sport medicine physician. Multiple multilevel Poisson regression analysis was performed, adjusting for important covariates and a random effect at a team level (offset by game exposure hours), to estimate injury and concussion incidence rate ratios (IRRs). RESULTS: In total, 1647 players participated, contributing 1842 player-seasons (195 players participating in two seasons). Relative to no body checking experience, no significant differences were found in the adjusted IRRs for game-related injury for players with 1 year (IRR=1.06; 95% CI: 0.77 to 1.45) or 2+ years (IRR=1.16; 95% CI: 0.74 to 1.84) body checking experience. Similarly, no differences were found in the rates of concussion for players with 1 year (IRR=0.92; 95% CI: 0.59 to 1.42) or 2+ years (IRR=0.69; 95% CI: 0.38 to 1.25) body checking experience. CONCLUSIONS: Among ice hockey players aged 13-14 years participating in leagues permitting body checking, the adjusted rates of all injury and concussion were not significantly different between those that had body checking experience and those that did not. Based on these findings, no association was found between body checking experience and rates of injury or concussion specifically in adolescent ice hockey.

Clodronate treatment significantly depletes macrophages in chickens.

Macrophages function as phagocytes and antigen-presenting cells in the body. As has been demonstrated in mammals, administration of clodronate [dichloromethylene bisphosphonate (Cl2MBP)] encapsulated liposomes results in depletion of macrophages. Although this compound has been used in chickens, its effectiveness in depleting macrophages has yet to be fully determined. Here, we show that a single administration of clodronate liposomes to chickens results in a significant depletion of macrophages within the spleen and lungs of chickens up to 4 d post-treatment. This finding suggests that, in order to obtain depletion of macrophages in chickens for greater than 5 d, it is necessary to administer clodronate liposomes 4 d apart. The study also showed that 2 treatments of clodronate liposomes at 4-day intervals resulted in the depletion of macrophages for up to 10 d. The findings of the present study will encourage more precise studies to be done on the potential roles of macrophages in immune responses and in the pathogenesis of microbial infections in chickens.

Les macrophages agissent comme phagocytes et cellules présentatrices d'antigènes dans l'organisme. Tel que démontré chez les mammifères, l'administration de liposomes encapsulés de clodronate [biphosphanate de dichlorométhylène (Cl2MBP)] cause une déplétion des macrophages. Bien que ce composé ait été utilisé chez les poulets, son efficacité à causer une déplétion des macrophages reste encore à être entièrement déterminée. Nous démontrons ici que l'administration d'une dose unique de liposomes de clodronate à des poulets a causé une déplétion significative des macrophages dans la rate et les poumons de poulets jusqu'à 4 j post-traitement. Cette trouvaille suggère qu'afin d'obtenir une déplétion des macrophages chez les poulets pour plus de 5 j, il est nécessaire d'administrer des liposomes de clodronate à un intervalle de 4 j. Cette étude a aussi démontré que deux traitements de liposomes de clodronate à 4 j d'intervalle a causé une déplétion des macrophages pour une durée allant jusqu'à 10 j. Les présentes trouvailles encourageront la mise en place d'études plus précises sur les rôles potentiels des macrophages dans la réponse immunitaire et dans la pathogénèse des infections microbiennes chez les poulets.(Traduit par Docteur Serge Messier).

Cell-type specific roles for PTEN in establishing a functional retinal architecture.

BACKGROUND: The retina has a unique three-dimensional architecture, the precise organization of which allows for complete sampling of the visual field. Along the radial or apicobasal axis, retinal neurons and their dendritic and axonal arbors are segregated into layers, while perpendicular to this axis, in the tangential plane, four of the six neuronal types form patterned cellular arrays, or mosaics. Currently, the molecular cues that control retinal cell positioning are not well-understood, especially those that operate in the tangential plane. Here we investigated the role of the PTEN phosphatase in establishing a functional retinal architecture. METHODOLOGY/PRINCIPAL FINDINGS: In the developing retina, PTEN was localized preferentially to ganglion, amacrine and horizontal cells, whose somata are distributed in mosaic patterns in the tangential plane. Generation of a retina-specific Pten knock-out resulted in retinal ganglion, amacrine and horizontal cell hypertrophy, and expansion of the inner plexiform layer. The spacing of Pten mutant mosaic populations was also aberrant, as were the arborization and fasciculation patterns of their processes, displaying cell type-specific defects in the radial and tangential dimensions. Irregular oscillatory potentials were also observed in Pten mutant electroretinograms, indicative of asynchronous amacrine cell firing. Furthermore, while Pten mutant RGC axons targeted appropriate brain regions, optokinetic spatial acuity was reduced in Pten mutant animals. Finally, while some features of the Pten mutant retina appeared similar to those reported in Dscam-mutant mice, PTEN expression and activity were normal in the absence of Dscam. CONCLUSIONS/SIGNIFICANCE: We conclude that Pten regulates somal positioning and neurite arborization patterns of a subset of retinal cells that form mosaics, likely functioning independently of Dscam, at least during the embryonic period. Our findings thus reveal an unexpected level of cellular specificity for the multi-purpose phosphatase, and identify Pten as an integral component of a novel cell positioning pathway in the retina.

Depressive-like behaviour of mice lacking cellular prion protein.

Cellular Prion Protein (PrP(C)) is known to mediate a protective role in several neurological conditions such as ischemia and epilepsy. However, so far, little information is available concerning the role of PrP(C) in psychiatric disorders such as depression. Here, we have used PrP(C) null mice to examine a putative role of PrP(C) in depressive-like states. Prion protein null mice exhibited depressive-like behaviour when compared to wild-type mice in both the Forced Swimming Test (FST) and Tail Suspension Test (TST). The clinical antidepressant drug imipramine and the NMDA receptor antagonist MK-801 reversed the depressive-like behaviour observed for knockout mice in the TST. The present data thus indicate that PrP(C) exerts a critical role in modulating the depressive-like state in mice, reinforcing the notion that PrP(C) might be associated with alterations in mood disorder states, and suggests a possible role of PrP(C) as a potential drug target for treating depressive disorders.

Walking with music is a safe and viable tool for gait training in Parkinson's disease: the effect of a 13-week feasibility study on single and dual task walking.

This study explored the viability and efficacy of integrating cadence-matched, salient music into a walking intervention for patients with Parkinson's disease (PD). Twenty-two people with PD were randomised to a control (CTRL, n = 11) or experimental (MUSIC, n = 11) group. MUSIC subjects walked with an individualised music playlist three times a week for the intervention period. Playlists were designed to meet subject's musical preferences. In addition, the tempo of the music closely matched (±10-15 bpm) the subject's preferred cadence. CTRL subjects continued with their regular activities during the intervention. The effects of training accompanied by "walking songs" were evaluated using objective measures of gait score. The MUSIC group improved gait velocity, stride time, cadence, and motor symptom severity following the intervention. This is the first study to demonstrate that music listening can be safely implemented amongst PD patients during home exercise.

The electroretinogram (ERG) of a diurnal cone-rich laboratory rodent, the Nile grass rat (Arvicanthis niloticus).

The most widespread models to study blindness, rats and mice, have retinas containing less than 3% cones. The diurnal rodent Arvicanthis niloticus retina has around 35% cones. Using ERG recordings, we studied retina function in this species. Several features differed from that reported in rats and mice: (a) fivefold larger photopic a-wave amplitudes; (b) photopic hill effect in Nile grass rats only; and (c) flicker amplitude plateau between 5 to 35 Hz with fusion beyond 60 Hz in Nile grass rats only. We conclude that A. niloticus might complement rats and mice for studying retinal function and pathologies involving cones.

Retinal anatomy and visual performance in a diurnal cone-rich laboratory rodent, the Nile grass rat (Arvicanthis niloticus).

Unlike laboratory rats and mice, muridae of the Arvicanthis family (A. ansorgei and A. niloticus) are adapted to functioning best in daylight. To date, they have been used as experimental models mainly in studies of circadian rhythms. However, recent work aimed at optimizing photoreceptor-directed gene delivery vectors (Khani et al. [2007] Invest Ophthalmol Vis Sci 48:3954-3961) suggests their potential usefulness for studying retinal pathologies and therapies. In the present study we analyzed the retinal anatomy and visual performance of the Nile grass rat (A. niloticus) using immunohistofluorescence and the optokinetic response (OKR). We found that approximately 35-40% of photoreceptors are cones; that many neural features of the inner retina are similar to those in other diurnal mammals; and that spatial acuity, measured by the OKR, is more than two times that of the usual laboratory rodents. These observations are consistent with the known diurnal habits of this animal, and further support its pertinence as a complementary model for studies of structure, function, and pathology in cone-rich mammalian retinae.

Modified Ca(v)1.4 expression in the Cacna1f(nob2) mouse due to alternative splicing of an ETn inserted in exon 2.

The Cacna1f(nob2) mouse is reported to be a naturally occurring null mutation for the Ca(v)1.4 calcium channel gene and the phenotype of this mouse is not identical to that of the targeted gene knockout model. We found two mRNA species in the Cacna1f(nob2) mouse: approximately 90% of the mRNA represents a transcript with an in-frame stop codon within exon 2 of CACNA1F, while approximately 10% of the mRNA represents a transcript in which alternative splicing within the ETn element has removed the stop codon. This latter mRNA codes for full length Ca(v)1.4 protein, detectable by Western blot analysis that is predicted to differ from wild type Ca(v)1.4 protein in a region of approximately 22 amino acids in the N-terminal portion of the protein. Electrophysiological analysis with either mouse Ca(v)1.4(wt) or Ca(v)1.4(nob2) cDNA revealed that the alternatively spliced protein does not differ from wild type with respect to activation and inactivation characteristics; however, while the wild type N-terminus interacted with filamin proteins in a biochemical pull-down experiment, the alternatively spliced N-terminus did not. The Cacna1f(nob2) mouse electroretinogram displayed reduced b-wave and oscillatory potential amplitudes, and the retina was morphologically disorganized, with substantial reduction in thickness of the outer plexiform layer and sprouting of bipolar cell dendrites ectopically into the outer nuclear layer. Nevertheless, the spatial contrast sensitivity (optokinetic response) of Cacna1f(nob2) mice was generally similar to that of wild type mice. These results suggest the Cacna1f(nob2) mouse is not a CACNA1F knockout model. Rather, alternative splicing within the ETn element can lead to full-length Ca(v)1.4 protein, albeit at reduced levels, and the functional Ca(v)1.4 mutant may be incapable of interacting with cytoskeletal filamin proteins. These changes, do not alter the ability of the Cacna1f(nob2) mouse to detect and follow moving sine-wave gratings compared to their wild type counterparts.

Corticofugal feedback for auditory midbrain plasticity elicited by tones and electrical stimulation of basal forebrain in mice.

The auditory cortex (AC) is the major origin of descending auditory projections and is one of the targets of the cholinergic basal forebrain, nucleus basalis (NB). In the big brown bat, cortical activation evokes frequency-specific plasticity in the inferior colliculus and the NB augments this collicular plasticity. To examine whether cortical descending function and NB contributions to collicular plasticity are different between the bat and mouse and to extend the findings in the bat, we induced plasticity in the central nucleus of the mouse inferior colliculus by a tone paired with electrical stimulation of the NB (hereafter referred to as tone-ES(NB)). We show here that tone-ES(NB) shifted collicular best frequencies (BFs) towards the frequency of the tone paired with ES(NB) when collicular BFs were different from tone frequency. The shift in collicular BF was linearly correlated to the difference between collicular BFs and tone frequencies. The changes in collicular BFs after tone-ES(NB) were similar to those found in the big brown bat. Compared with cortical plasticity evoked by tone-ES(NB), the pattern of collicular BF shifts was identical but the shifting range of collicular BFs was narrower. A GABA(A) agonist (muscimol) or a muscarinic acetylcholine receptor antagonist (atropine) applied to the AC completely abolished the collicular plasticity evoked by tone-ES(NB). Therefore, our findings strongly suggest that the AC plays a critical role in experience-dependent auditory plasticity through descending projections.