Publications by authors named "Daniel J Brown"

46 Publications

Model definition for genetic evaluation of purebred and crossbred lambs including heterosis.

J Anim Sci 2022 Jun;100(6)

Department of Animal Science, University of Nebraska - Lincoln, Lincoln, NE 68583, USA.

Crossbreeding is a common practice among commercial sheep producers to improve animal performance. However, genetic evaluation of U.S. sheep is performed within breed type (terminal sire, semi-prolific, and western range). While incorporating crossbred records may improve assessment of purebreds, it requires accounting for heterotic and breed effects in the evaluation. The objectives of this study were to: 1) describe the development of a paternal composite (PC) line, 2) determine the effect of direct and maternal heterosis on growth traits of crossbred lambs, 3) estimate (co)variance components for direct and maternal additive, and uncorrelated maternal environmental, effects, and 4) provide an interpretation of the estimates of random effects of genetic groups, and to use those solutions to compare the genetic merit of founding breed subpopulations. Data included purebred and crossbred records on birth weight (BN; n = 14,536), pre-weaning weight measured at 39 or 84 d (WN; n = 9,362) depending on year, weaning weight measured at 123 d (WW; n = 9,297), and post-weaning weight measured at 252 d (PW; n = 1,614). Mean (SD) body weights were 5.3 (1.1), 16.8 (3.9) and 28.0 (7.6), 39.1 (7.2), and 54.2 (8.7) kg for BN, WN (at the two ages), WW, and PW, respectively. In designed experiments, the Siremax, Suffolk, Texel, Polypay, Columbia, Rambouillet, and Targhee breeds were compared within the same environment. Estimates of heterotic effects and covariance components were obtained using a multiple trait animal model. Genetic effects based on founders' breeds were significant and included in the model. Percent estimates of direct heterosis were 2.89 ± 0.61, 2.60 ± 0.65, 4.24 ± 0.56, and 6.09 ± 0.86, and estimates of maternal heterosis were 1.92 ± 0.87, 4.64 ± 0.80, 3.95 ± 0.66, and 4.04 ± 0.91, for BN, WN, WW, and PW, respectively. Correspondingly, direct heritability estimates were 0.17 ± 0.02, 0.13 ± 0.02, 0.17 ± 0.02, and 0.46 ± 0.04 for BN, WN, WW, and PW. Additive maternal effects accounted for trivial variation in PW. For BN, WN, and WW, respectively, maternal heritability estimates were 0.16 ± 0.02, 0.10 ± 0.02, and 0.07 ± 0.01. Uncorrelated maternal environmental effects accounted for little variation in any trait. Direct and maternal heterosis had considerable impact on growth traits, emphasizing the value of crossbreeding and the need to account for heterosis, in addition to breed effects, if crossbred lamb information is included in genetic evaluation.
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http://dx.doi.org/10.1093/jas/skac188DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC9191838PMC
June 2022

Relevance of Deployment Experience and Clinical Practice Characteristics on Military Critical Care Air Transport Team Readiness: A Study of Simulation Construct Validity.

Mil Med 2022 May 27. Epub 2022 May 27.

Center for Sustainment of Trauma and Readiness Skills, University of Cincinnati, Cincinnati, OH 45219, USA.

Introduction: The Critical Care Air Transport Team (CCATT) Advanced course utilizes fully immersive high-fidelity simulations to train CCATT personnel and assess their readiness for deployment. This study aims to (1) determine whether these simulations correctly discriminate between students with previous deployment experience ("experienced") and no deployment experience ("novices") and (2) examine the effects of students' clinical practice environment on their performance during training simulations.

Materials And Methods: Critical Care Air Transport Team Advanced student survey data and course status (pass/no pass) between March 2006 and April 2020 were analyzed. The data included students' specialty, previous exposure to the CCATT Advanced course, previous CCATT deployment experience, years in clinical practice (<5, 5-15, and >15 years), and daily practice of critical care (yes/no), as well as a description of the students' hospital to include the total number of hospital (<100, 100-200, 201-400, and >400) and intensive care unit (0, 1-10, 11-20, and >20) beds. Following descriptive analysis and comparative tests, multivariable regression was used to identify the predictors of passing the CCATT Advanced course.

Results: A total of 2,723 surveys were analyzed: 841 (31%) were physicians (MDs), 1,035 (38%) were registered nurses, and 847 (31%) were respiratory therapists (RTs); 641 (24%) of the students were repeating the course for sustainment training and 664 (24%) had previous deployment experience. Grouped by student specialty, the MDs', registered nurses', and RTs' pass rates were 92.7%, 90.6%, and 85.6%, respectively. Multivariable regression results demonstrated that deployment experience was a robust predictor of passing. In addition, the >15 years in practice group had a 47% decrease in the odds of passing as compared to the 5 to 15 years in practice group. Finally, using MDs as the reference, the RTs had a 61% decrease in their odds of passing. The daily practice of critical care provided a borderline but nonsignificant passing advantage, whereas previous CCATT course exposure had no effect.

Conclusion: Our primary result was that the CCATT Advanced simulations that are used to evaluate whether the students are mission ready successfully differentiated "novice" from "experienced" students; this is consistent with valid simulation constructs. Finally, novice CCATT students do not sustain their readiness skills during the period between mandated refresher training.
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http://dx.doi.org/10.1093/milmed/usac142DOI Listing
May 2022

Descriptive Analysis of Intratheater Critical Care Air Transport Team Patient Movements During Troop Drawdown: Afghanistan (2017-2019).

Mil Med 2022 Apr 21. Epub 2022 Apr 21.

Department of Surgery, University of Cincinnati, Cincinnati, OH 45219, USA.

Background: The majority of critical care air transport (CCAT) flights are regulated, meaning that a theater-validating flight surgeon has confirmed that the patient is medically cleared for flight and that evacuation is appropriate. If the conditions on the ground do not allow for this process, the flight is unregulated. Published data are limited regarding CCAT unregulated missions to include the period of troop drawdown at the end of the Afghanistan conflict. The objective of our study was to characterize the unregulated missions within Afghanistan during troop drawdown and compare them to regulated missions during the same timeframe.

Study Design: We performed a retrospective review of all CCAT medical records of patients transported via CCAT within Afghanistan between January 2017 and December 2019. We abstracted data from the records, including mission characteristics, patient demographics, injury descriptors, preflight military treatment facility procedures, CCAT procedures, in-flight CCAT treatments, in-flight events, and equipment issues. Following descriptive and comparative analysis, a Cochran-Armitage test was performed to evaluate the statistical significance of the trend in categorical data over time. Multivariable regression was used to assess the association between vasopressors and preflight massive transfusions, preflight surgical procedures, injury patterns, and age.

Results: We reviewed 147 records of patients transported via CCAT: 68 patients were transported in a regulated fashion and 79 on an unregulated flight. The number of patients evacuated increased year-over-year (n = 22 in 2017, n = 57 in 2018, and n = 68 in 2019, P < .001), and the percentage of missions that were unregulated grew geometrically (14%, n = 3 in 2017; 37%, n = 21 in 2018; and 81%, n = 55 in 2019, P < .001). During the time studied, CCAT teams were being used more to decompress forward surgical teams (FST) and, therefore, they were transporting patients just hours following initial damage control surgery in an unregulated fashion. In 2 instances, CCAT decompressed an FST following a mass casualty, during which aeromedical evacuation (AE) crews assisted with patient care. For the regulated missions, the treatments that were statistically more common were intravenous fluids, propofol, norepinephrine, any vasopressors, and bicarbonate. During unregulated missions, the statistically more common treatments were ketamine, fentanyl, and 3% saline. Additional analysis of the mechanically ventilated patient subgroup revealed that vasopressors were used twice as often on regulated (38%) vs. unregulated (13%) flights. Multivariable regression analysis demonstrated that traumatic brain injury (TBI) was the only significant predictor of in-flight vasopressor use (odds ratio = 3.53, confidence interval [1.22, 10.22], P = .02).

Conclusion: During the troop drawdown in Afghanistan, the number of unregulated missions increased geometrically because the medical footprint was decreasing. During unregulated missions, CCAT providers used ketamine more frequently, consistent with Tactical Combat Casualty Care guidelines. In addition, TBI was the only predictor of vasopressor use and may reflect an attempt to adhere to unmonitored TBI clinical guidelines. Interoperability between CCAT and AE teams is critical to meet mass casualty needs in unregulated mission environments and highlights a need for joint training. It remains imperative to evaluate changes in mission requirements to inform en route combat casualty care training.
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http://dx.doi.org/10.1093/milmed/usac097DOI Listing
April 2022

Dysfunctional movement patterning in the hand: an unrecognized entity?

J Hand Surg Eur Vol 2022 07 13;47(7):779-781. Epub 2022 Mar 13.

Department of Trauma and Orthopaedics, Liverpool University Hospitals NHS FT, Liverpool, UK.

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http://dx.doi.org/10.1177/17531934221085838DOI Listing
July 2022

Exploring patients' experiences of the impact of dialysis therapies on quality of life and wellbeing.

J Ren Care 2022 Feb 28. Epub 2022 Feb 28.

School of Sport, Health and Exercise Sciences, Faculty of Science and Health, University of Portsmouth, Portsmouth, UK.

Background: When people with chronic kidney disease reach kidney failure, renal replacement therapy is usually required to improve symptoms and maintain life. Although in-centre haemodialysis is most commonly used for this purpose, other forms of dialysis are available, including home haemodialysis and peritoneal dialysis.

Objectives: We aimed to explore the experiences of adults living with chronic kidney disease who were either approaching the need for dialysis or had reached kidney failure and were receiving a form of dialysis. In particular, we explored how different forms of dialysis affect their quality of life, wellbeing, and physical activity.

Methods: Individual semistructured interviews were conducted with 40 adults with kidney failure, comprising four groups (n = 10 each): those receiving in-centre haemodialysis, home haemodialysis or peritoneal dialysis, or predialysis. Interviews were transcribed verbatim, thematically analysed, and then composite vignettes were subsequently developed to present a rich narrative of the collective experiences of each group.

Findings: Compared with adults who were predialysis, quality of life and wellbeing improved upon initiation of their home haemodialysis or peritoneal dialysis. Conversely, minimal improvement was perceived by those receiving in-centre haemodialysis. Low physical activity was reported across all four groups, although those receiving home haemodialysis and peritoneal dialysis reported a greater desire and ability to be physically active than those in-centre.

Conclusion: These findings highlight that dialysis modalities not requiring regular hospital attendance (i.e., home haemodialysis and peritoneal dialysis) improve independence, quality of life, wellbeing, and can facilitate a more physically active lifestyle.
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http://dx.doi.org/10.1111/jorc.12416DOI Listing
February 2022

A Dual-Process Model Applied to Two Health-Promoting Nutrition Behaviours.

Behav Sci (Basel) 2021 Dec 8;11(12). Epub 2021 Dec 8.

School of Applied Psychology, Griffith University, Brisbane 4122, Australia.

We tested a dual process model incorporating constructs that reflect both performing the target behaviour (behaviour directed habit) and habits that run counter to the target behaviour (opposing behaviour habit) in accounting for variance in two health behaviours: eating the recommended serves of fruits and vegetables a day and restricting sugar-sweetened beverage consumption. A prospective correlational design with two waves of data collection separated by one week was adopted. Participants ( = 606) comprising middle school students ( = 266) and university students ( = 340) completed an initial survey comprising self-report measures of past behaviour, intention, and habit to perform the target behaviour and habits that run counter to the target behaviour. One week later, participants ( = 414) completed a self-reported measure of behaviour. Results revealed that behaviour directed habits predicted fruit and vegetable consumption in both samples, while opposing behaviour habits predicted restriction of sugar-sweetened beverages in the middle-school sample only, with a moderating effect also observed. Current findings indicate that habits specifying avoidance of the target behaviour did not predict future behaviour. However, the moderating effect observed provides preliminary evidence that strong habits to perform a behaviour may override habit to avoid the behaviour.
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http://dx.doi.org/10.3390/bs11120170DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8698688PMC
December 2021

Letter about a Published Paper.

J Hand Surg Eur Vol 2021 10;46(8):901-902

Trauma and Orthopaedics, Liverpool University Hospitals Foundation NHS Trust, Liverpool, UK.

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http://dx.doi.org/10.1177/17531934211008364DOI Listing
October 2021

Similarities and Differences Between Vestibular and Cochlear Systems - A Review of Clinical and Physiological Evidence.

Front Neurosci 2021 12;15:695179. Epub 2021 Aug 12.

School of Pharmacy and Biomedical Sciences, Curtin University, Bentley, WA, Australia.

The evoked response to repeated brief stimuli, such as clicks or short tone bursts, is used for clinical evaluation of the function of both the auditory and vestibular systems. One auditory response is a neural potential - the Auditory Brainstem Response (ABR) - recorded by surface electrodes on the head. The clinical analogue for testing the otolithic response to abrupt sounds and vibration is the myogenic potential recorded from tensed muscles - the vestibular evoked myogenic potential (VEMP). VEMPs have provided clinicians with a long sought-after tool - a simple, clinically realistic indicator of the function of each of the 4 otolithic sensory regions. We review the basic neural evidence for VEMPs and discuss the similarities and differences between otolithic and cochlear receptors and afferents. VEMPs are probably initiated by sound or vibration selectively activating afferent neurons with irregular resting discharge originating from the unique type I receptors at a specialized region of the otolithic maculae (the striola). We review how changes in VEMP responses indicate the functional state of peripheral vestibular function and the likely transduction mechanisms allowing otolithic receptors and afferents to trigger such very short latency responses. In section "ELECTROPHYSIOLOGY" we show how cochlear and vestibular receptors and afferents have many similar electrophysiological characteristics [e.g., both generate microphonics, summating potentials, and compound action potentials (the vestibular evoked potential, VsEP)]. Recent electrophysiological evidence shows that the hydrodynamic changes in the labyrinth caused by increased fluid volume (endolymphatic hydrops), change the responses of utricular receptors and afferents in a way which mimics the changes in vestibular function attributed to endolymphatic hydrops in human patients. In section "MECHANICS OF OTOLITHS IN VEMPS TESTING" we show how the major VEMP results (latency and frequency response) follow from modeling the physical characteristics of the macula (dimensions, stiffness etc.). In particular, the structure and mechanical operation of the utricular macula explains the very fast response of the type I receptors and irregular afferents which is the very basis of VEMPs and these structural changes of the macula in Menière's Disease (MD) predict the upward shift of VEMP tuning in these patients.
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http://dx.doi.org/10.3389/fnins.2021.695179DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8397526PMC
August 2021

Thriving Through Relationships in Sport: The Role of the Parent-Athlete and Coach-Athlete Attachment Relationship.

Front Psychol 2021 2;12:694599. Epub 2021 Aug 2.

Faculty of Arts and Social Sciences, Karlstad University, Karlstad, Sweden.

The aim of this research was to examine whether attachment relationships to significant others, such as to parents and/or sports coaches, enable thriving and competition performance within sport. Two studies employing cross-sectional and prospective designs were carried out across different samples of athletes of varied skill levels and sports. In Study 1, we found athletes' attachment to their sports coach was significantly associated with athlete thriving and mediated by psychological needs satisfaction. Results of Study 2 found that athletes' secure attachment to their mother and/or father positively predicted the experience of thriving at the competition while athletes' insecure attachment did not predict thriving. Furthermore, athletes' attachment to both mother and father did not predict competition performance. Together, these two studies acknowledge the significant role that athletes' secure attachment relationships with parents and coaches play in facilitating thriving in athletes. These findings have significant implications for research and practice.
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http://dx.doi.org/10.3389/fpsyg.2021.694599DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8366224PMC
August 2021

Genomic prediction in a numerically small breed population using prioritized genetic markers from whole-genome sequence data.

J Anim Breed Genet 2022 Jan 10;139(1):71-83. Epub 2021 Aug 10.

School of Environmental and Rural Science, University of New England, Armidale, NSW, Australia.

The objective of this study was to investigate the accuracy of genomic prediction of body weight and eating quality traits in a numerically small sheep population (Dorper sheep). Prediction was based on a large multi-breed/admixed reference population and using (a) 50k or 500k single nucleotide polymorphism (SNP) genotypes, (b) imputed whole-genome sequencing data (~31 million), (c) selected SNPs from whole genome sequence data and (d) 50k SNP genotypes plus selected SNPs from whole-genome sequence data. Furthermore, the impact of using a breed-adjusted genomic relationship matrix on accuracy of genomic breeding value was assessed. The selection of genetic variants was based on an association study performed on imputed whole-genome sequence data in an independent population, which was chosen either randomly from the base population or according to higher genetic proximity to the target population. Genomic prediction was based on genomic best linear unbiased prediction (GBLUP), and the accuracy of genomic prediction was assessed according to the correlation between genomic breeding value and corrected phenotypes divided by the square root of trait heritability. The accuracy of genomic prediction was between 0.20 and 0.30 across different traits based on common 50k SNP genotypes, which improved on average by 0.06 (absolute value) on average based on using prioritized genetic markers from whole-genome sequence data. Using prioritized genetic markers from a genetically more related GWAS population resulted in slightly higher prediction accuracy (0.02 absolute value) compared to genetic markers derived from a random GWAS population. Using high-density SNP genotypes or imputed whole-genome sequence data in GBLUP showed almost no improvement in genomic prediction accuracy however, accounting for different marker allele frequencies in reference population according to a breed-adjusted GRM resulted to on average 0.024 (absolute value) increase in accuracy of genomic prediction.
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http://dx.doi.org/10.1111/jbg.12638DOI Listing
January 2022

Summating potentials from the utricular macula of anaesthetized guinea pigs.

Hear Res 2021 07 13;406:108259. Epub 2021 May 13.

Curtin Medical School, Curtin University, Bentley, WA 6102, Australia.

The Summating Potential (SP) was first recorded in the cochlea in the 1950s and represents an objective measure of cochlear hair cell function, in vivo. Despite being a regular tool in hearing research, a similar response has not yet been recorded from the vestibular system. This is mainly due to the lack of experimental techniques available to record electrical vestibular hair cell responses in isolation from the much larger cochlear potentials. Here we demonstrate the first recordings of the vestibular SP, evoked by Bone-Conducted Vibration (BCV) and Air-Conducted Sound (ACS) stimuli, in anaesthetized guinea pigs. Field potential measurements were taken from the basal surface of the utricular macula, and from the facial nerve canal following surgical or chemical ablation of the cochlea. SPs were evoked by stimuli with frequencies above ~200 Hz, and only with moderate to high intensity (~0.005-0.05 g) BCV and ACS (~120-140 dB SPL). Neural blockade abolished the Vestibular short-latency Evoked Potential (VsEP) and Vestibular Nerve Neurophonic (VNN) from the facial nerve canal recordings but did not abolish the vestibular SP nor the vestibular microphonic. Importantly, the vestibular SP was irreversibly abolished from the utricle and facial nerve canal recordings following local gentamicin application, highlighting its hair cell origin. This is the first study to record the Summating Potential from the mammalian vestibular system, in vivo, providing a novel research tool to assess vestibular hair cell function during experimental manipulations and animal models of disease.
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http://dx.doi.org/10.1016/j.heares.2021.108259DOI Listing
July 2021

Understanding the Impact of Initial COVID-19 Restrictions on Physical Activity, Wellbeing and Quality of Life in Shielding Adults with End-Stage Renal Disease in the United Kingdom Dialysing at Home versus In-Centre and Their Experiences with Telemedicine.

Int J Environ Res Public Health 2021 03 18;18(6). Epub 2021 Mar 18.

School of Sport, Health and Exercise Sciences, Faculty of Science and Health, University of Portsmouth, Portsmouth PO1 2UP, UK.

Early in the coronavirus-2019 (COVID-19) containment strategy, people with end-stage renal disease (ESRD) were identified as extremely clinically vulnerable and subsequently asked to 'shield' at home where possible. The aim of this study was to investigate how these restrictions and the transition to an increased reliance on telemedicine within clinical care of people living with kidney disease impacted the physical activity (PA), wellbeing and quality of life (QoL) of adults dialysing at home (HHD) or receiving in-centre haemodialysis (ICHD) in the UK. Individual semistructured telephone interviews were conducted with adults receiving HHD ( = 10) or ICHD ( = 10), were transcribed verbatim and, subsequently, thematically analysed. As result of the COVID-19 restrictions, PA, wellbeing and QoL of people with ESRD were found to have been hindered. However, widespread support for the continued use of telemedicine was strongly advocated and promoted independence and satisfaction in patient care. These findings highlight the need for more proactive care of people with ESRD if asked to shield again, as well as increased awareness of safe and appropriate PA resources to help with home-based PA and emotional wellbeing.
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http://dx.doi.org/10.3390/ijerph18063144DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8002886PMC
March 2021

To strive or survive: An exploration of the meaning and inhibitors to thriving in surgical performance.

Am J Surg 2021 09 17;222(3):504-505. Epub 2021 Mar 17.

Discipline of Surgery, School of Medicine, Trinity College Dublin, The University of Dublin, Ireland.

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http://dx.doi.org/10.1016/j.amjsurg.2021.03.010DOI Listing
September 2021

Reducing the incidence of pin site infection in hand surgery with the use of a protocol from Ilizarov.

J Hand Surg Eur Vol 2021 Jun 7;46(5):482-487. Epub 2021 Feb 7.

Department of Trauma and Orthopaedics, Liverpool University Hospitals NHS FT, Liverpool, UK.

Reported pin site infection rates in Kirschner wire fixation in the hand and wrist vary from 2% to 35%. In our unit we follow a strict pin site management protocol adapted from the Russian Ilizarov Scientific Centre. This study aims to identify if our current protocol reduces the incidence of pin site infection in hand and wrist surgery, and improves wire survival rates, to a level where exposed wires can be used safely. A retrospective review of 200 patients, treated with 369 percutaneous wires, in our hand surgery department over a 6-year period was carried out. Nine patients (4.5%) were diagnosed with a pin site infection with a wire survival rate of 99.5%.In our unit using our current protocol, results support the safe use of exposed wires with appropriate pin site care initiated in theatre. Adherence to this protocol allows wires to remain in-situ throughout treatment with minimal complications. IV.
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http://dx.doi.org/10.1177/1753193421991318DOI Listing
June 2021

A Study Comparing the Outcomes of Transverse Ulnar Shortening Osteotomy Fixed with a DCP to Oblique Osteotomy Fixed with a Procedure Specific Plate.

J Hand Surg Asian Pac Vol 2020 Dec;25(4):441-446

Liverpool University Hospitals NHS Foundation Trust, Liverpool, UK.

Ulnar shortening osteotomy (USO) is a well-established procedure for ulnar impaction syndrome. Various types of osteotomies have been described. A retrospective cohort study was conducted to compare the results of transverse osteotomy (TO) fixed with a small fragment dynamic compression plate (Synthes, Pennsylvania, USA), to oblique osteotomy (OO) fixed with a procedure specific plate and instrumentation system (Acumed LLC, Oregon, USA). A total of 39 patients underwent TO and 62 patients underwent OO between 2007 and 2016. The main outcomes compared were rate of union, duration of radiological healing, implant removal rate and other complications. The two groups were comparable with regards to demographics, side operated and smoking status ( > 0.05). Amongst the TO group; 36 out of 39 patients (92.3%) achieved union, 3 patients (7.7%) developed non-union. Six out of the 36 healed TO (16.6%) required removal of hardware due to implant-related pain. No other complications were recorded amongst TO group needing surgical intervention. Amongst the OO group, 2 of the early cohort of 62 patients (3.2%) sustained acute failure of the metalwork due to technical error. One of the remaining 60 patients (1.6%) developed non-union giving an overall union rate of 95.2%. Two patients out of 59 healed OO (3.3%) required removal of hardware. Although there were 2 early failures, there was a trend towards improved union rate with OO, but this did not reach statistical significance ( > 0.05). There was a significantly higher hardware removal rate recorded in TO group ( = 0.023). The OO showed shorter duration for radiological healing than TO ( < 0.05). USO performed with an OO and fixed with procedure specific plate has lower implant removal rate, a shorter duration for radiological healing and comparable union rate to TO fixed with DCP, but needs careful attention to detail.
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http://dx.doi.org/10.1142/S2424835520500484DOI Listing
December 2020

The prediction of thriving in elite sport: A prospective examination of the role of psychological need satisfaction, challenge appraisal, and salivary biomarkers.

J Sci Med Sport 2021 Apr 8;24(4):373-379. Epub 2020 Oct 8.

School of Sport, Exercise, and Health Sciences, Loughborough University, United Kingdom.

Objectives: To examine (i) whether levels of, and changes in, athletes' basic psychological need satisfaction (BPNS) and challenge appraisals predicted in-match thriving; and (ii) if salivary biomarkers could be defined that were related to thriving.

Design: Prospective study design.

Methods: Fifty-one elite male hockey players (M=24.94 years, SD=4.73) completed questionnaires measuring their BPNS and challenge appraisals on seven consecutive days prior to a competitive match, as well as providing saliva samples immediately on waking, and then +0.5, +3, and +5.25h on the day of the match. Saliva was assayed for catabolic (i.e., cortisol) and anabolic (i.e., dehydroepiandrosterone [DHEA]) hormones. In-match thriving was assessed retrospectively using measures of subjective performance and well-being.

Results: Latent growth curve modelling showed pre-match levels of BPNS and challenge appraisals to positively predict thriving. Although not statistically significant, small and moderate negative associations were found for thriving with cortisol concentration (+5.25h sample) and total cortisol exposure across the morning of the match, respectively. DHEA concentration shared a small positive, yet non-significant, association with thriving.

Conclusions: Athletes' pre-match levels of BPNS and challenge appraisal predict in-match thriving; thus, offering potential mechanisms through which both high-level performance and the experience of well-being can be facilitated. Furthermore, associations suggest that total cortisol exposure across the morning of the match, and cortisol and DHEA levels in pre-match samples may offer sport science and sports medicine practitioners potential biomarkers for thriving. Future research is required to substantiate this initial finding.
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http://dx.doi.org/10.1016/j.jsams.2020.09.019DOI Listing
April 2021

Incidence of tendon ruptures after locking plate fixation of distal radial fractures: are the cited rates still accurate?

J Hand Surg Eur Vol 2021 Feb 13;46(2):167-171. Epub 2020 Aug 13.

Department of Trauma and Orthopaedics, Liverpool University Hospitals NHS FT, Liverpool, UK.

With the introduction of the anterior locking plate in the early part of this century, there was a large change in how distal radial fractures were treated. Early articles about the techniques reported tendon ruptures occurring in as many as 10%, although studies from our unit reported rates closer to 2%. Subsequent refinements in surgical technique and improvements in plate design have been made with the aim of reducing the number of ruptures. Despite this, the original articles and their rates continue to be quoted. In this retrospective study of 798 cases treated with anterior locking plates, tendon ruptures have been significantly reduced and are now as low as 0.5%. Contributing factors leading to this improvement are identified and discussed. III.
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http://dx.doi.org/10.1177/1753193420948466DOI Listing
February 2021

The mediating role of constructs representing reasoned-action and automatic processes on the past behavior-future behavior relationship.

Soc Sci Med 2020 08 30;258:113085. Epub 2020 May 30.

Griffith University, Australia.

Objective: Past behavior has been consistently shown to predict and explain future behavior. It has been proposed that past behavior effects reflect both reasoned action and automatic processes. The current study sought to explore the mediation of past behavior-future behavior relationship via constructs reflecting these processes across three populations and behaviors: binge drinking in university students, flossing in adults, and parental sun safety behavior of children 2 - 5 years of age. Furthermore, this study used a measure of past behavior that combined long-term, recent, and routine patterns of behavioral engagement.

Method: A prospective design with two waves of data collection spaced six weeks apart was adopted. Participants (total N = 754) completed an initial survey containing measures of past behavior (frequency, recency, and routine), social cognition (attitudes, subjective norms, perceived behavioral control), and behavioral automaticity. Six weeks later, participants (N = 454) completed a self-report measure of behavior and behavioral automaticity.

Results: Structural equation modelling revealed that automatic, but not reasoned-action processes, mediated the past-to-future relationship, across the three behaviors. Results further revealed that long-term, recent, and routine patterns of behavioral engagement were highly correlated and indicated a second-order past behavior latent variable.

Conclusions: While both reasoned-action and automatic factors can predict a range of health behaviors, automatic processes appear to explain the effect of past behavior on future behavior. Further investigations should focus on exploring the role of other non-conscious and automatic processes such as counter-intentional habits and implicit beliefs in explaining engagement in heath behaviors.
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http://dx.doi.org/10.1016/j.socscimed.2020.113085DOI Listing
August 2020

A review of mechanical and synaptic processes in otolith transduction of sound and vibration for clinical VEMP testing.

J Neurophysiol 2019 07 1;122(1):259-276. Epub 2019 May 1.

School of Biomedical Sciences and Pharmacy, The University of Newcastle and Hunter Medical Research Institute. Newcastle, New South Wales, Australia.

Older studies of mammalian otolith physiology have focused mainly on sustained responses to low-frequency (<50 Hz) or maintained linear acceleration. So the otoliths have been regarded as accelerometers. Thus evidence of otolithic activation and high-precision phase locking to high-frequency sound and vibration appears to be very unusual. However, those results are exactly in accord with a substantial body of knowledge of otolith function in fish and frogs. It is likely that phase locking of otolith afferents to vibration is a general property of all vertebrates. This review examines the literature about the activation and phase locking of single otolithic neurons to air-conducted sound and bone-conducted vibration, in particular the high precision of phase locking shown by mammalian irregular afferents that synapse on striolar type I hair cells by calyx endings. Potassium in the synaptic cleft between the type I hair cell receptor and the calyx afferent ending may be responsible for the tight phase locking of these afferents even at very high discharge rates. Since frogs and fish do not possess full calyx endings, it is unlikely that they show phase locking with such high precision and to such high frequencies as has been found in mammals. The high-frequency responses have been modeled as the otoliths operating in a seismometer mode rather than an accelerometer mode. These high-frequency otolithic responses constitute the neural basis for clinical vestibular-evoked myogenic potential tests of otolith function.
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http://dx.doi.org/10.1152/jn.00031.2019DOI Listing
July 2019

Genetic correlations between meat quality traits and growth and carcass traits in Merino sheep1.

J Anim Sci 2018 Sep;96(9):3582-3598

Cooperative Research Centre for Sheep Industry Innovation, University of New England, Armidale, NSW, Australia.

Genetic correlations between 16 meat quality and nutritional value traits and live weight at various ages, live ultrasound fat and muscle depth, carcass measures, and carcass dissection traits were estimated for Merino sheep in the Information Nucleus (IN). Genetic correlations between live weight at various ages and the carcass traits are also reported. The IN comprised 8 genetically linked flocks managed across a range of Australian sheep environments. Meat quality traits included between 1,200 and 1,300 records for progeny from over 170 sires for intramuscular fat (IMF), lean meat yield (LMY), shear force (SF5), pH, meat color, and meat nutritional value traits including iron and zinc levels and long-chain omega-3 and omega-6 polyunsaturated fatty acid levels. The genetic correlations indicated that selection of Merino sheep to either reduce fat or increase muscle using ultrasound assessments will result in little change in IMF and SF5. Myoglobin levels would tend to be reduced following selection for reduced ultrasound fat depth (0.35 ± 0.21, 0.43 ± 0.14), whereas increases in myoglobin levels would occur due to selection for increased ultrasound muscle depth (0.25 ± 0.24, 0.38 ± 0.15). Selection for increased live weight will result in favorable correlated responses in hot carcass weight (0.76 to 0.97), dressing percentage (0.13 to 0.47), and carcass muscle (0.37 to 0.95), but unfavorable responses of increases in carcass fatness (0.13 to 0.65) and possible small reductions in muscle oxidative activity (-0.13 ± 0.14 to -0.73 ± 0.33) and iron content (-0.14 ± 0.15 to -0.38 ± 0.16), and a possible deterioration of shear force from selection at later ages (0.15 ± 0.26, 0.27 ± 0.24). Negligible changes are generally expected for LMY and meat color traits following selection for increased live weight (most genetic correlations less than 0.20 in size). Selection for increased LMY would tend to result in unfavorable changes in several aspects of meat quality, including reduced IMF (-0.27 ± 0.18), meat tenderness (0.53 ± 0.26), and meat redness (-0.69 ± 0.40), as well as reduced iron levels (-0.25 ± 0.22). These genetic correlations are a first step in assisting the development of breeding values for new traits to be incorporated into genetic evaluation programs to improve meat production from Merino sheep and other dual-purpose sheep breeds.
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http://dx.doi.org/10.1093/jas/sky232DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6127828PMC
September 2018

Otolithic Receptor Mechanisms for Vestibular-Evoked Myogenic Potentials: A Review.

Front Neurol 2018 25;9:366. Epub 2018 May 25.

MSA ENT Academy Center, Cassino, Italy.

Air-conducted sound and bone-conduced vibration activate otolithic receptors and afferent neurons in both the utricular and saccular maculae, and trigger small electromyographic (EMG) responses [called vestibular-evoked myogenic potentials (VEMPs)] in various muscle groups throughout the body. The use of these VEMPs for clinical assessment of human otolithic function is built on the following logical steps: (1) that high-frequency sound and vibration at clinically effective stimulus levels activate otolithic receptors and afferents, rather than semicircular canal afferents, (2) that there is differential anatomical projection of otolith afferents to eye muscles and neck muscles, and (3) that isolated stimulation of the utricular macula induces short latency responses in eye muscles, and that isolated stimulation of the saccular macula induces short latency responses in neck motoneurons. Evidence supports these logical steps, and so VEMPs are increasingly being used for clinical assessment of otolith function, even differential evaluation of utricular and saccular function. The proposal, originally put forward by Curthoys in 2010, is now accepted: that the ocular vestibular-evoked myogenic potential reflects predominantly contralateral utricular function and the cervical vestibular-evoked myogenic potential reflects predominantly ipsilateral saccular function. So VEMPs can provide differential tests of utricular and saccular function, not because of stimulus selectivity for either of the two maculae, but by measuring responses which are predominantly determined by the differential neural projection of utricular as opposed to saccular neural information to various muscle groups. The major question which this review addresses is how the otolithic sensory system, with such a high density otoconial layer, can be activated by individual cycles of sound and vibration and show such tight locking of the timing of action potentials of single primary otolithic afferents to a particular phase angle of the stimulus cycle even at frequencies far above 1,000 Hz. The new explanation is that it is due to the otoliths acting as seismometers at high frequencies and accelerometers at low frequencies. VEMPs are an otolith-dominated response, but in a particular clinical condition, semicircular canal dehiscence, semicircular canal receptors are also activated by sound and vibration, and act to enhance the otolith-dominated VEMP responses.
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http://dx.doi.org/10.3389/fneur.2018.00366DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5980960PMC
May 2018

Thriving on Pressure: A Factor Mixture Analysis of Sport Performers' Responses to Competitive Encounters.

J Sport Exerc Psychol 2017 Dec 13;39(6):423-437. Epub 2018 Feb 13.

3 Loughborough University.

Although considerable research exists on performers' responses to sporting encounters, little is known about thriving in sport contexts. The current study examined if distinct response patterns existed between sport performers who thrived in competitive encounters compared with those who did not. Participants were 535 sport performers (134 women; M = 23.60 years, SD = 8.08; M = 11.84 years, SD = 7.11). Results of factor mixture analysis supported a four-profile solution comprising a thriving group (n = 146), a low-functioning group (n = 38), and two groups characterized by scores marginally above (n = 131) and below (n = 209) the sample mean. Profile membership was found to be predicted by personal enablers (viz., personal resilient qualities, psychological skills use) and process variables (viz., basic psychological need satisfaction and frustration, challenge appraisal). This examination of thriving in sport performers offers significant implications for research and practice.
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http://dx.doi.org/10.1123/jsep.2016-0293DOI Listing
December 2017

Suppression of the vestibular short-latency evoked potential by electrical stimulation of the central vestibular system.

Hear Res 2018 04 2;361:23-35. Epub 2018 Feb 2.

The Meniere's Laboratory, Sydney Medical School, The University of Sydney, Sydney, NSW, 2050, Australia. Electronic address:

In an attempt to view the effects of the efferent vestibular system (EVS) on peripheral dynamic vestibular function, we have monitored the Vestibular short-latency Evoked Potential (VsEP) evoked by pulses of bone conducted vibration during electrical stimulation of the EVS neurons near the floor of the fourth ventricle in the brainstem of anesthetized guinea pigs. Given the reported effects of EVS on primary afferent activity, we hypothesized that EVS stimulation would cause a slight reduction in the VsEP amplitude. Our results show a substantial (>50%) suppression of the VsEP, occurring immediately after a single EVS current pulse. The effect could not be blocked by cholinergic drugs which have been shown to block efferent-mediated vestibular effects. Shocks produced a short-latency P1-N1 response immediately after the electrical artifact which correlated closely to the VsEP suppression. Ultimately, we have identified that this suppression results from antidromic blockade of the afferent response (the VsEP). It would appear that this effect is unavoidable for EVS stimulation, as we found no other effects.
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http://dx.doi.org/10.1016/j.heares.2018.01.013DOI Listing
April 2018

Multiple-trait QTL mapping and genomic prediction for wool traits in sheep.

Genet Sel Evol 2017 08 15;49(1):62. Epub 2017 Aug 15.

Agriculture Victoria Research, AgriBio Centre, Bundoora, VIC, 3083, Australia.

Background: The application of genomic selection to sheep breeding could lead to substantial increases in profitability of wool production due to the availability of accurate breeding values from single nucleotide polymorphism (SNP) data. Several key traits determine the value of wool and influence a sheep's susceptibility to fleece rot and fly strike. Our aim was to predict genomic estimated breeding values (GEBV) and to compare three methods of combining information across traits to map polymorphisms that affect these traits.

Methods: GEBV for 5726 Merino and Merino crossbred sheep were calculated using BayesR and genomic best linear unbiased prediction (GBLUP) with real and imputed 510,174 SNPs for 22 traits (at yearling and adult ages) including wool production and quality, and breech conformation traits that are associated with susceptibility to fly strike. Accuracies of these GEBV were assessed using fivefold cross-validation. We also devised and compared three approximate multi-trait analyses to map pleiotropic quantitative trait loci (QTL): a multi-trait genome-wide association study and two multi-trait methods that use the output from BayesR analyses. One BayesR method used local GEBV for each trait, while the other used the posterior probabilities that a SNP had an effect on each trait.

Results: BayesR and GBLUP resulted in similar average GEBV accuracies across traits (~0.22). BayesR accuracies were highest for wool yield and fibre diameter (>0.40) and lowest for skin quality and dag score (<0.10). Generally, accuracy was higher for traits with larger reference populations and higher heritability. In total, the three multi-trait analyses identified 206 putative QTL, of which 20 were common to the three analyses. The two BayesR multi-trait approaches mapped QTL in a more defined manner than the multi-trait GWAS. We identified genes with known effects on hair growth (i.e. FGF5, STAT3, KRT86, and ALX4) near SNPs with pleiotropic effects on wool traits.

Conclusions: The mean accuracy of genomic prediction across wool traits was around 0.22. The three multi-trait analyses identified 206 putative QTL across the ovine genome. Detailed phenotypic information helped to identify likely candidate genes.
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http://dx.doi.org/10.1186/s12711-017-0337-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5558709PMC
August 2017

Premier League academy soccer players' experiences of competing in a tournament bio-banded for biological maturation.

J Sports Sci 2018 Apr 19;36(7):757-765. Epub 2017 Jun 19.

j Department of Kinesiology and Health Education , University of Texas at Austin , Austin , TX , USA.

Individual differences in the growth and maturation have been shown to impact player performance and development in youth soccer. This study investigated Premier League academy players' experiences of participating in a tournament bio-banded for biological maturation. Players (N = 66) from four professional soccer clubs aged 11 and 14 years and between 85-90% of adult stature participated in a tournament. Players competed in three 11 vs 11 games on a full size pitch with 25-min halves. Sixteen players participated in four 15-min focus groups and were asked to describe their experiences of participating in the bio-banded tournament in comparison to age group competition. All players described their experience as positive and recommended the Premier League integrate bio-banding into the existing games programme. In comparison to age-group competitions, early maturing players described the bio-banded games more physically challenging, and found that they had to adapt their style of play placing a greater emphasis on technique and tactics. Late maturing players considered the games to be less physically challenging, yet appreciated the having more opportunity to use, develop and demonstrate their technical, physical, and psychological competencies. Bio-banding strategies appear to contribute positively towards the holistic development of young soccer players.
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http://dx.doi.org/10.1080/02640414.2017.1340656DOI Listing
April 2018

Electrophysiological Measurements of Peripheral Vestibular Function-A Review of Electrovestibulography.

Front Syst Neurosci 2017 31;11:34. Epub 2017 May 31.

Department of Psychology, The University of SydneySydney, NSW, Australia.

Electrocochleography (EcochG), incorporating the Cochlear Microphonic (CM), the Summating Potential (SP), and the cochlear Compound Action Potential (CAP), has been used to study cochlear function in humans and experimental animals since the 1930s, providing a simple objective tool to assess both hair cell (HC) and nerve sensitivity. The vestibular equivalent of ECochG, termed here (EVestG), incorporates responses of the vestibular HCs and nerve. Few research groups have utilized EVestG to study vestibular function. Arguably, this is because stimulating the cochlea in isolation with sound is a trivial matter, whereas stimulating the vestibular system in isolation requires significantly more technical effort. That is, the vestibular system is sensitive to both high-level sound and bone-conducted vibrations, but so is the cochlea, and gross electrical responses of the inner ear to such stimuli can be difficult to interpret. Fortunately, several simple techniques can be employed to isolate vestibular electrical responses. Here, we review the literature underpinning gross vestibular nerve and HC responses, and we discuss the nomenclature used in this field. We also discuss techniques for recording EVestG in experimental animals and humans and highlight how EVestG is furthering our understanding of the vestibular system.
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http://dx.doi.org/10.3389/fnsys.2017.00034DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5450778PMC
May 2017

Endolymph movement visualized with light sheet fluorescence microscopy in an acute hydrops model.

Hear Res 2016 09 1;339:112-24. Epub 2016 Jul 1.

University of Utrecht, Faculty Nature and Technique, Inst. for Life Sciences and Chemistry, Utrecht, 3508 AD, The Netherlands.

There are a variety of techniques available to investigate endolymph dynamics, primarily seeking to understand the cause of endolymphatic hydrops. Here we have taken the novel approach of injecting, via a glass micropipette, fluorescein isothiocyanate-dextran (FITC-dex) and artificial endolymph into scala media of anaesthetized guinea pigs, with subsequent imaging of the inner ear using Light Sheet Fluorescence Microscopy (LSFM) as a means to obtain highly resolved 3D visualization of fluid movements. Our results demonstrate endolymph movement into the utricle, semicircular canals and endolymphatic duct and sac when more than 2.5 μl of fluid had been injected into scala media, with no apparent movement of fluid into the perilymphatic compartments. There was no movement of endolymph into these compartments when less than 2.5 μl was injected. The remarkable uptake of the FITC-dex into the endolymphatic duct, including an absorption into the periductal channels surrounding the endolymphatic duct, highlights the functional role this structure plays in endolymph volume regulation.
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http://dx.doi.org/10.1016/j.heares.2016.06.007DOI Listing
September 2016

Effects of Psychological and Psychosocial Interventions on Sport Performance: A Meta-Analysis.

Sports Med 2017 Jan;47(1):77-99

School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough, UK.

Background: Psychologists are increasingly supporting the quest for performance enhancement in sport and there is a need to evaluate the evidence base underpinning their work.

Objectives: To synthesize the most rigorous available research that has evaluated psychological, social, and psychosocial interventions with sport performers on variables relating to their athletic performance, and to address some of the perplexing issues in the sport psychology intervention literature (e.g., do interventions have a lasting effect on sport performance?).

Methods: Randomized controlled trials were identified through electronic databases, hand-searching volumes of pertinent journals, scrutinizing reference lists of previous reviews, and contacting experts in the evaluation of interventions in this field. Included studies were required to evaluate the effects of psychological, social, or psychosocial interventions on sport performance in athletes when compared to a no-treatment or placebo-controlled treatment comparison group. A random effects meta-analysis calculating the standardized mean difference (Hedges' g), meta-regressions, and trim and fill analyses were conducted. Data were analyzed at post-test and follow-up (ranging from 1 to 4 weeks after the intervention finished) assessments.

Results: Psychological and psychosocial interventions were shown to enhance sport performance at post-test (k = 35, n = 997, Hedges' g = 0.57, 95 % CI = 0.22-0.92) and follow-up assessments (k = 8, n = 189, Hedges' g = 1.16, 95 % CI = 0.25-2.08); no social interventions were included or evaluated. Larger effects were found for psychosocial interventions and there was some evidence that effects were greatest in coach-delivered interventions and in samples with a greater proportion of male participants.

Conclusions: Psychological and psychosocial interventions have a moderate positive effect on sport performance, and this effect may last at least a month following the end of the intervention. Future research would benefit from following guidelines for intervention reporting.
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http://dx.doi.org/10.1007/s40279-016-0552-7DOI Listing
January 2017

The role of fracture reduction and plate position in the aetiology of flexor pollicis longus tendon rupture after volar plate fixation of distal radius fractures.

Hand (N Y) 2015 Sep;10(3):497-502

Department of Orthopaedics, Royal Liverpool University Hospital, Prescot Street, Liverpool, L7 8XP UK.

Background: Flexor pollicis longus (FPL) rupture has been described as complication following volar plating for distal radius fractures. It has been hypothesised that this is due to plate prominence. The aim of the study was to investigate the relationship between sub-optimal plate position and fracture reduction on plate prominence.

Methods: Plate prominence was measured in two experimental models. In the first, the effect of plate position was investigated using 18 fresh frozen cadavers with prominence being measured using a micrometer. In the second study, the effect of fracture reduction on plate prominence was investigated using similar methodology with simulated mal-reductions on dry bone models.

Results: The results of the first study showed a significant increase in lift-off for three plates (DVR, Synthes Universal and Acu-Loc), if the plates were moved distally or proximally from the anatomical position. Similar increases in prominence were also seen with rotational mal-positions. The results of the second study showed a statistically significant effect on plate prominence for even a 5° mal-reduction (p = 0.001) with worsening lift-off with increasing mal-reduction. These changes are significantly different from baseline and also significantly different to the lift-off recorded with mal-reductions 5° better and worse. Mal-reductions also necessitate more proximal placement of the plate to avoid screw penetration of the articular surface, and each 5° increment is significantly different from baseline.

Conclusions: The results show a statistically and clinically significant effect of both plate position and fracture reduction on plate prominence and support the theory that both contribute to the aetiology of post-operative FPL rupture.
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http://dx.doi.org/10.1007/s11552-014-9735-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4551651PMC
September 2015

Effects of birth-rearing type on weaning weights in meat sheep are systematically associated with differences in mean performance among flocks.

Genet Sel Evol 2015 Jul 3;47:57. Epub 2015 Jul 3.

Animal Genetics and Breeding Unit, University of New England, Armidale, NSW, 2351, Australia.

Background: Adjustment of body weights for systematic environmental effects such as dam age and litter size is essential for accurate prediction of breeding values in meat sheep and often accomplished by pre-adjusting records using simple multiplicative adjustment factors, which are derived as ratios of least-squares means of weights of lambs in target and reference classes. However, increasing use of multibreed genetic evaluations that incorporate data from both purebred and commercial flocks has generated concerns regarding the ability of simple additive or multiplicative adjustment factors to properly correct for environmental effects in flocks that differ widely in mean performance. Thus, consistency of adjustment factors across flocks and systematic effects of the level of flock performance on these factors were evaluated using data from the US National Sheep Improvement Program.

Methods: We used birth and weaning weights of lambs from 29 flocks that had at least 500 records per flock and represented several terminal-sire sheep breeds. Effects of lamb sex, dam age class and litter size on birth weights, and of dam age class and combined effects of type of birth and rearing on weaning weights were evaluated. Interactions between these effects and flock were assessed. Bias associated with different adjustment protocols was evaluated for high- and low-performance flocks.

Results: Effects of litter size and differences between yearling and adult dams varied (P < 0.001) among flocks. For weaning weights, additive adjustment factors were not associated with the level of flock performance, but multiplicative adjustment factors were strongly and inversely related to flock means for weaning weights (W). Flock-specific adjustment factors (F = αW(β)) reduced bias in adjusted weaning weights associated with differences in flock performance. By contrast, simple multiplicative adjustment factors were appropriate to adjust birth weights.

Conclusions: Differences in weaning weights among single, twin, and triplet lambs were inversely related to the level of flock performance. Use of simple multiplicative adjustment factors led to adjustment bias when applied across flocks with large differences in mean performance. This bias was reduced by using additive adjustment factors or multiplicative factors that were derived as simple exponential functions of flock means for weaning weight.
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http://dx.doi.org/10.1186/s12711-015-0136-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4489108PMC
July 2015
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