Bacterial osteomyelitis in pediatric patients: a comprehensive review.

Bacterial osteomyelitis, an inflammatory response in the bone caused by microorganisms, typically affects the metaphysis in the skeletally immature. Bacterial osteomyelitis possesses a significant diagnostic challenge in pediatric patients due to its nonspecific clinical presentation. Because the metaphysis is the primary focus of infection in skeletally immature patients, understanding the normal physiologic, maturation process of bones throughout childhood allows to understand the pathophysiology of osteomyelitis. Timely and accurate diagnosis is crucial to initiate appropriate treatment, and prevent long-term sequelae and efforts must be made to isolate the causative organism. The potential causative organism changes according to the age of the patient and underlying medical conditions. Staphylococcus Aureus is the most common isolated bacteria in pediatric pyogenic osteomyelitis whereas Kingella Kingae is the most common causative agent in children aged 6 months to 4 years. Imaging plays a pivotal role in the diagnosis, characterization, evaluation of complications, and follow up of bacterial osteomyelitis. Imaging also plays a pivotal role in the evaluation of potential neoplastic and non-neoplastic mimickers of osteomyelitis. In children, MRI is currently the gold standard imaging modality when suspecting bacterial osteomyelitis, whereas surgical intervention may be required in order to isolate the microorganism, treat complications, and exclude mimickers.

Effects of Activation Barriers on Quenching to Stabilize Prebiotic Chemical Systems.

We have previously shown in model studies that rapid quenches of systems of monomers interacting to form polymer chains can fix nonequilibrium chemistries with some lifelike properties. We suggested that such quenching processes might have occurred at very high rates on early Earth, giving an efficient mechanism for natural sorting through enormous numbers of nonequilibrium chemistries from which the most lifelike ones could be naturally selected. However, the model used for these studies did not take account of activation barriers to polymer scission (peptide bond hydrolysis in the case of proteins). Such barriers are known to exist and are expected to enhance the quenching effect. Here, we introduce a modified model which takes activation barriers into account and we compare the results to data from experiments on quenched systems of amino acids. We find that the model results turn out to be sensitive to the width of the distribution of barrier heights but quite insensitive to its average value. The results of the new model are in significantly better agreement with the experiments than those found using our previous model. The new parametrization of the model only requires one new parameter and the parametrization is more physical than the previous one, providing a chemical interpretation of the parameter p in our previous models. Within the model, a characteristic temperature Tc emerges such that if the temperature of the hot stage is above Tc and the temperature of the cold stage is below it, then the 'freezing out', in a quench, of a disequilibrium ensemble of long polymers is expected. We discuss the possible relevance of this to models of the origin of life in emissions from deep ocean rifts.

Contrast-Enhanced Ultrasound of the Chest in Children and Adolescents: A Pilot Study for Assessment of Added Diagnostic Value.

OBJECTIVES: To determine the added diagnostic value of contrast-enhanced ultrasound (CEUS) in pediatric chest abnormalities by comparing interpretation of CEUS studies and confidence level to conventional US studies. METHODS: CEUS studies in patients with a variety of clinically suspected chest abnormalities performed between 2016 and 2020 were reviewed and compared to same-day conventional US studies. Examinations were independently interpreted by 4 radiologists blinded to clinical and other imaging data. Rater confidence was classified as low, moderate, or high. Diagnostic accuracy was determined by comparing image interpretation to patient outcome as the ground truth. Interobserver agreement was also assessed. RESULTS: Sixteen patients (10 male) with 18 CEUS studies were included. Median rater agreement with ground truth was significantly higher for CEUS (100%) than conventional US (50%; P = .004). Median rater confidence was high (3.0) for CEUS, and low-moderate (1.5) for conventional US (P < .001). CEUS sensitivity (54.6-81.8%) and specificity (63.4-100.0%) were greater than conventional US (45.5-72.7% and 12.5-63.5%, respectively). CEUS false positives (0-4) and false negatives (2-5) were fewer than conventional US (4-7 and 3-6, respectively). Except for one rater pair where agreement was substantial (κ = .78, P < .01), inter-rater agreement for CEUS for all other rater pairs was nonsignificant (κ = .25-0.51, P ≥ .07). Agreement for conventional US was moderate and statistically significant for 3 rater pairs (κ = .55-0.78) and nonsignificant for the remaining 3 rater pairs (P ≥ .06). CONCLUSIONS: CEUS adds diagnostic value to the assessment of a variety of chest abnormalities. The data support further evaluation of the role of CEUS as a non-invasive, problem-solving technique in children.

Decreased serotonin transporter activity in the mitral valve contributes to progression of degenerative mitral regurgitation.

Degenerative mitral valve (MV) regurgitation (MR) is a highly prevalent heart disease that requires surgery in severe cases. Here, we show that a decrease in the activity of the serotonin transporter (SERT) accelerates MV remodeling and progression to MR. Through studies of a population of patients with MR, we show that selective serotonin reuptake inhibitor (SSRI) use and SERT promoter polymorphism 5-HTTLPR LL genotype were associated with MV surgery at younger age. Functional characterization of 122 human MV samples, in conjunction with in vivo studies in SERT-/- mice and wild-type mice treated with the SSRI fluoxetine, showed that diminished SERT activity in MV interstitial cells (MVICs) contributed to the pathophysiology of MR through enhanced serotonin receptor (HTR) signaling. SERT activity was decreased in LL MVICs partially because of diminished membrane localization of SERT. In mice, fluoxetine treatment or SERT knockdown resulted in thickened MV leaflets. Similarly, silencing of SERT in normal human MVICs led to up-regulation of transforming growth factor ß1 (TGFß1) and collagen (COL1A1) in the presence of serotonin. In addition, treatment of MVICs with fluoxetine not only directly inhibited SERT activity but also decreased SERT expression and increased HTR2B expression. Fluoxetine treatment and LL genotype were also associated with increased COL1A1 expression in the presence of serotonin in MVICs, and these effects were attenuated by HTR2B inhibition. These results suggest that assessment of both 5-HTTLPR genotype and SERT-inhibiting treatments may be useful tools to risk-stratify patients with MV disease to estimate the likelihood of rapid disease progression.

Some Factors from Theory, Simulation, Experiment and Proteomes in the Current Biosphere Supporting Deep Oceans as the Location of the Origin of Terrestrial Life.

Some standard arguments are reviewed supporting deep ocean trenches as a likely location for the origin of terrestrial life. An analysis of proteomes of contemporary prokaryotes carried out by this group is cited as supporting evidence, indicating that the original proteins were formed by quenching from temperatures close to the boiling point of water. Coarse-grained simulations of the network formation process which agree quite well with experiments of such quenches both in drying and rapid fluid emission from a hot to a cold fluid are also described and cited as support for such a scenario. We suggest further experiments, observations and theoretical and simulation work to explore this hypothesis.

Secondary Pulmonary Vein Stenosis Due to Total Anomalous Pulmonary Venous Connection Repair in Children: Extravascular MDCT Findings.

PURPOSE: To evaluate extravascular findings on thoracic MDCT angiography in secondary pulmonary vein stenosis (PVS) due to total anomalous pulmonary venous connection (TAPVC) repair in children. MATERIALS AND METHODS: All patients aged ≤18 years with a known diagnosis of secondary PVS after TAPVC repair, confirmed by echocardiography, conventional angiography, and/or surgery, who underwent thoracic MDCT angiography studies between July 2008 and April 2021 were included. Two pediatric radiologists independently examined MDCT angiography studies for the presence of extravascular thoracic abnormalities in the lung, pleura, and mediastinum. The location and distribution of each abnormality (in relation to the location of PVS) were also evaluated. Interobserver agreement between the two independent pediatric radiology reviewers was studied using kappa statistics. RESULTS: The study group consisted of 20 consecutive pediatric patients (17 males, 3 females) with secondary PVS due to TAPVC repair. Age ranged from 2 months to 8 years (mean, 16.1 months). In children with secondary PVS due to TAPVC repair, the characteristic extravascular thoracic MDCT angiography findings were ground-glass opacity (19/20; 95%), septal thickening (7/20; 35%), pleural thickening (17/20; 85%), and a poorly defined, mildly heterogeneously enhancing, non-calcified soft tissue mass (17/20; 85%) which followed the contours of affected pulmonary veins outside the lung. There was excellent interobserver kappa agreement between two independent reviewers for detecting extravascular abnormalities on thoracic MDCT angiography studies (k = 0.99). CONCLUSION: Our study characterizes the extravascular thoracic MDCT angiography findings in secondary pediatric PVS due to TAPVC repair. In the lungs and pleura, ground-glass opacity, interlobular septal thickening, and pleural thickening are common findings. Importantly, the presence of a mildly heterogeneously enhancing, non-calcified mediastinal soft tissue mass in the distribution of the PVS is a novel characteristic thoracic MDCT angiography finding seen in pediatric secondary PVS due to TAPVC repair.

Extravascular MDCT Findings of Pulmonary Vein Stenosis in Children with Cardiac Septal Defect.

Purpose: To retrospectively investigate the extravascular thoracic MDCT angiography findings of pulmonary vein stenosis (PVS) in children with a cardiac septal defect. Materials and Methods: Pediatric patients (age ≤ 18 years) with cardiac septal defect and PVS, confirmed by echocardiogram and/or conventional angiography, who underwent thoracic MDCT angiography studies from April 2009 to April 2021 were included. Two pediatric radiologists independently evaluated thoracic MDCT angiography studies for the presence of extravascular thoracic abnormalities in: (1) lung and airway (ground-glass opacity (GGO), consolidation, pulmonary nodule, mass, cyst, septal thickening, fibrosis, and bronchiectasis); (2) pleura (pleural thickening, pleural effusion, and pneumothorax); and (3) mediastinum (mass and lymphadenopathy). Interobserver agreement between the two independent pediatric radiology reviewers was evaluated with kappa statistics. Results: The final study group consisted of 20 thoracic MDCT angiography studies from 20 consecutive individual pediatric patients (13 males (65%) and 7 females (35%); mean age: 7.5 months; SD: 12.7; range: 2 days to 7 months) with cardiac septal defect and PVS. The characteristic extravascular thoracic MDCT angiography findings were GGO (18/20; 90%), septal thickening (9/20; 45%), pleural thickening (16/20; 80%), and ill-defined, mildly heterogeneously enhancing, non-calcified soft tissue mass (9/20; 45%) following the contours of PVS in the mediastinum. There was a high interobserver kappa agreement between two independent reviewers for detecting extravascular abnormalities on thoracic MDCT angiography studies (k = 0.99). Conclusion: PVS in children with a cardiac septal defect has a characteristic extravascular thoracic MDCT angiography finding. In the lungs and pleura, GGO, septal thickening, and pleural thickening are frequently seen in children with cardiac septal defect and PVS. In the mediastinum, a mildly heterogeneously enhancing, non-calcified soft tissue mass in the distribution of PVS in the mediastinum is seen in close to half of the pediatric patients with cardiac septal defect and PVS.

Thoracic Multidetector Computed Tomography Findings of Dedicator of Cytokinesis 8 Deficiency in Children.

PURPOSE: To investigate the characteristic thoracic multidetector computed tomography (MDCT) findings of dedicator of cytokinesis 8 (DOCK8) deficiency, a rare autosomal recessive form of hyperimmunoglobulin E syndrome, in children. MATERIALS AND METHODS: All pediatric patients (age 18 y and below) with a known diagnosis of DOCK8 deficiency based on genetic testing who underwent thoracic MDCT studies from November 2004 to November 2020 were included. Two pediatric radiologists independently evaluated MDCT studies for the presence of thoracic abnormalities in the lung [ground-glass opacity (GGO), consolidation, pulmonary nodule, mass, cyst, and bronchiectasis], pleura (pleural effusion and pneumothorax), and mediastinum (lymphadenopathy). When a lung abnormality was present, laterality, distribution (upper, middle, and lower lung zone), and extent were also evaluated. When a pleural abnormality was identified, laterality and size of the abnormality were also assessed. When mediastinal lymphadenopathy was present, its location and size were also evaluated. Interobserver agreement between two independent reviewers was evaluated with κ statistics. RESULTS: In all, 17 thoracic MDCT studies from 17 individual pediatric patients [5 males (29%) and 12 females (71%); mean age: 7.4 y; SD: 3.7; range: 1 to 13 y] comprised the final study population. Among 17 thoracic MDCT studies, 11 studies (65%) were performed with intravenous contrast (IV) and the remaining 6 MDCT studies (35%) were obtained without IV contrast. Bilateral bronchiectasis (11/17; 65%) with a middle lung zone predominance (8/11; 73%) was the most frequently detected lung abnormality, followed by GGO in 9/17 patients (53%). Among 11 contrast-enhanced MDCT studies, the majority (9 patients, 82%) had mediastinal lymphadenopathy. There was excellent interobserver κ agreement between 2 independent reviewers for detecting abnormalities on thoracic MDCT studies (κ>0.90). CONCLUSION: Children with DOCK8 deficiency have characteristic thoracic MDCT findings, including bilateral bronchiectasis with a middle lung zone predominance, GGO, and mediastinal lymphadenopathy. When these characteristic thoracic MDCT findings are detected, although rare, DOCK8 deficiency should be considered as a possible underlying diagnosis in the pediatric population.

Thoracic MDCT findings of a combined congenital lung lesion: Bronchial atresia associated with congenital pulmonary airway malformation.

PURPOSE: To investigate the characteristic thoracic multidetector computed tomography (MDCT) findings of pathologically proven combined congenital lung lesion consisting of bronchial atresia (BA) and congenital pulmonary airway malformation (CPAM) in children. MATERIALS AND METHODS: All pediatric patients (age ≤ 18 years) with a known pathological diagnosis of a combined BA-CPAM congenital lung lesion, who underwent thoracic MDCT studies from January 2011 to January 2021 were included. Two pediatric radiologists independently evaluated thoracic MDCT studies for the presence of abnormalities in the lung, including nodule, mass, cyst, ground-glass opacity, and consolidation. When a lung abnormality was present, the number, size, composition (solid, cystic, or combination of both), borders (well-circumscribed vs. ill-defined), contrast enhancement pattern (nonenhancement vs. enhancement), and location (laterality, and lobar distribution) were also evaluated. Interobserver agreement between two independent reviewers was evaluated with κ statistics. RESULTS: Eighteen contrast-enhanced thoracic MDCT studies from 18 individual pediatric patients (8 males (44%) and 10 females (56%); mean age: 4.9 months; SD: 2.6; range: 1-10 months) with a pathological diagnosis of combined BA-CPAM congenital lung lesion comprised the final study population. The most frequent MDCT finding of combined BA-CPAM congenital lung lesion in children was a solitary (18/18; 100%), well-circumscribed (18/18; 100%), both solid and cystic (17/18; 94%) lesion with nonenhancing (17/17; 100%) nodule, reflecting the underlying BA component, adjacent to a well-circumscribed multicystic mass (18/18; 100%), representing the underlying CPAM component. This combined congenital lung lesion occurred in all lobes with similar frequency. There was almost perfect interobserver κ agreement between the two independent reviewers for detecting abnormalities on thoracic MDCT studies (k = 0.98). CONCLUSION: The characteristic thoracic MDCT findings of a combined BA-CPAM congenital lung lesion are a solitary, well-circumscribed solid and multicystic mass, with a nonenhancing nodule, reflecting the BA component, adjacent to a cystic mass, representing the CPAM component. Accurate recognition of these characteristic MDCT findings of combined BA-CPAM congenital lung lesion has great potential to help differentiate this combined congenital lung lesion from other thoracic pathology in children.

Thoracic Multidetector Computed Tomography Angiography of Primary Pulmonary Vein Stenosis in Children: Evaluation of Characteristic Extravascular Findings.

PURPOSE: The purpose of this study was to investigate the extravascular thoracic multidetector computed tomography (MDCT) angiography findings of pediatric primary pulmonary vein stenosis (PVS) by comparing extravascular thoracic MDCT angiography findings in children with and without PVS. MATERIALS AND METHODS: All pediatric patients (age 18 y and below) with a known diagnosis of primary PVS, confirmed by echocardiogram and/or conventional angiography, who underwent thoracic MDCT angiography studies from July 2006 to December 2020 were included. A comparison group, comprised of age-matched and sex-matched pediatric patients without PVS who underwent thoracic MDCT angiography studies during the same study period, was also generated. Two pediatric radiologists independently evaluated thoracic MDCT angiography studies for the presence of extravascular thoracic abnormalities in the lung (ground-glass opacity [GGO], consolidation, pulmonary nodule, mass, cyst, septal thickening, fibrosis, and bronchiectasis), pleura (pleural thickening, pleural effusion and pneumothorax), and mediastinum (lymphadenopathy and mass). When a thoracic abnormality was identified, the location and distribution of the abnormality (in relation to the location of PVS) were also evaluated. Extravascular thoracic MDCT angiography findings of pediatric patients with and without primary PVS were compared. Interobserver agreement between the 2 independent reviewers was evaluated with κ statistics. RESULTS: The study group consisted of 15 thoracic MDCT angiography studies from 15 individual pediatric patients with primary PVS (8 males [53%] and 7 females [47%]; mean age: 10.9 mo; SD: 11.7 mo; range: 1 to 48 mo). The comparison group consisted of 15 thoracic MDCT angiography studies from 15 individual pediatric patients without PVS (8 males [53%] and 7 females [47%]; mean age: 10.2 mo; SD: 11.5 mo; range: 1 to 48 mo). In children with primary PVS, the characteristic extravascular thoracic MDCT angiography findings were GGO (14/15; 93%), septal thickening (5/15; 33%), pleural thickening (14/15; 93%), and ill-defined, mildly heterogeneously enhancing, noncalcified soft tissue mass (14/15; 93%) following the contours of PVS in the mediastinum. There was excellent interobserver κ agreement between 2 independent reviewers for detecting extravascular abnormalities on thoracic MDCT angiography studies (κ=0.99 for the study group and κ=0.98 for the comparison group). CONCLUSIONS: Children with primary PVS have characteristic extravascular thoracic MDCT angiography findings. In the lungs and pleura, GGO, septal thickening, and pleural thickening are common findings. Importantly, in the mediastinum, the presence of a mildly heterogeneously enhancing, noncalcified soft tissue mass in the distribution of PVS is a novel characteristic thoracic MDCT angiography finding unique to pediatric primary PVS. When this constellation of extravascular thoracic MDCT angiography findings is detected, although rare, primary PVS should be considered as a possible underlying diagnosis, especially in symptomatic children.

Thoracic Multidetector Computed Tomography Evaluation of Inflammatory Myofibroblastic Tumor of the Lung in Pediatric Patients in the Era of Modern Diagnosis.

PURPOSE: The purpose of this study was to investigate the characteristic thoracic multidetector computed tomography (MDCT) findings of pathologically proven inflammatory myofibroblastic tumor (IMT) of the lung in children in the era of modern understanding based on refined pathologic diagnosis. MATERIALS AND METHODS: All pediatric patients (age 18 y and above) with a known pathologic diagnosis of IMT of the lung who underwent thoracic MDCT studies from May 2008 to December 2020 were included. Two pediatric radiologists independently evaluated thoracic MDCT studies for the presence of abnormalities in the lung (nodule, mass, cyst, ground-glass opacity, consolidation), pleura (pleural effusion, pneumothorax), and mediastinum and hilum (lymphadenopathy). When a lung abnormality was present, the number, size, composition (solid, cystic, or combination of both), location (laterality, lobar distribution, and intraparenchymal vs. pleural-based), borders (well-circumscribed vs. ill-defined), the presence and type of associated calcification (punctate, dense, curvilinear, or flocculent), the presence of associated cavitation, contrast enhancement pattern (homogeneous, heterogenous, central, or peripheral), and other associated findings (neural foramen involvement, anomalous vessels, mass effect, and invasion of adjacent thoracic structures) were also evaluated. Interobserver agreement between 2 independent reviewers was evaluated with κ statistics. RESULTS: In all, 12 thoracic MDCT studies from 12 individual pediatric patients (5 males [42%] and 7 females [58%]; mean age: 9.9 y; SD: 4.4 y; range: 2 to 16 y) comprised the final study population. All 12 thoracic MDCT studies (100%) were performed with intravenous contrast. The most frequent MDCT finding of IMT of the lung in children is a solitary (92%), pleural-based (83%), well-circumscribed (100%), solid (92%) mass with heterogenous contrast enhancement (100%), often with dense calcification (50%), which occurred in both lungs and all lobes with similar frequency. No pleural abnormality (pleural effusion, pneumothorax) or mediastinal abnormality (lymphadenopathy) was detected. In addition, although mass effect on adjacent thoracic structures was frequently seen (42%), no invasion, neural foramen involvement, or associated anomalous vessels was identified. There was excellent interobserver κ agreement between 2 independent reviewers for detecting abnormalities on thoracic MDCT studies (κ>0.95). CONCLUSIONS: IMT of the lung in children typically presents as a solitary, pleural-based, well-circumscribed, solid mass with heterogenous contrast enhancement, often with dense calcification, without significant laterality or lobar preference. In addition, pleural or mediastinal abnormalities are characteristically absent. These notable MDCT attributes of IMT of the lung are an important and novel finding, with great potential to help differentiate pediatric IMT of the lung from other thoracic masses in children.

Quenching to fix metastable states in models of prebiotic chemistry.

For prebiotic chemistry to succeed in producing a starting metastable, autocatalytic and reproducing system subject to evolutionary selection it must satisfy at least two apparently contradictory requirements: Because such systems are rare, a search among vast numbers of molecular combinations must take place naturally, requiring rapid rearrangement and breaking of covalent bonds. But once a relevant system is found, such rapid disruption and rearrangement would be very likely to destroy the system before much evolution could take place. In this paper we explore the possibility, using a model developed previously, that the search process could occur under different environmental conditions than the subsequent fixation and growth of a lifelike chemical system. We use the example of a rapid change in temperature to illustrate the effect and refer to the rapid change as a "quench"borrowing terminology from study of the physics and chemistry of glass formation. The model study shows that interrupting a high-temperature nonequilibrium state with a rapid quench to lower temperatures can substantially increase the probability of producing a chemical state with lifelike characteristics of nonequilibrium metastability, internal dynamics and exponential population growth in time. Previously published data on the length distributions of proteomes of prokaryotes may be consistent with such an idea and suggest a prebiotic high-temperature "search" phase near the boiling point of water. A rapid change in pH could have a similar effect. We discuss possible scenarios on early Earth which might have allowed frequent quenches of the sort considered here to have occurred. The models show a strong dependence of the effect on the number of chemical monomers available for bond formation.

Some generic measures of the extent of chemical disequilibrium applied to living and abiotic systems.

We report results of evaluation of several measures of chemical disequilibrium in living and abiotic systems. The previously defined measures include R_{T} and R_{L}, which are Euclidean distances of a coarse grained polymer length distribution from two different chemical equilibrium states associated with equilibration to an external temperature bath and with isolated equilibration to a distribution determined by the bond energy of the system, respectively. The determination uses a simplified description of the energetics of the constituent molecules. We evaluated the measures for data from the ribosome of E. coli, a variety of yeast, and the proteomes (with certain assumptions) of a large family of prokaryotes, and for mass spectrometric data from the atmosphere of the Saturn satellite Titan and for nonliving commercial copolymers. We find with surprising consistency that R_{L} is much smaller than R_{T} for all these systems. The living (protein) systems have a well defined value of R_{T} that is sharply defined and distinct from that obtained from the nonliving Titan and copolymer systems. The living systems are also distinguishably characterized by larger values of R_{L} than most of the nonliving systems, but R_{L} values vary more from one living system to another than the R_{T} values do. These data suggest that the measures R_{L} and R_{T} can distinguish living from nonliving systems.

Effect of dietary amino acid density on broiler breeder reproductive performance.

The effects of 3 dietary amino acid (AA) profiles during lay on reproductive performance of broiler breeders were investigated. A flock of 2,376 Ross 708 female broiler breeders were randomly divided into 3 treatments with 12 replicates of 66 females per replicate, and fed 2 breeder feed phases (breeder 1: 25 to 36 wk; breeder 2: 37 to 60 wk) which were formulated to 3 different AA densities (Aviagen advice = control; 10% increased AA in Aviagen advice = high-AA; and estimated AA needs for maintenance, growth, and egg mass = estimated-AA). No differences in total or hatching egg production due to dietary treatments were observed. Hens fed high-AA had a higher incidence of double-yolk eggs. During the second phase of lay, hens fed estimated-AA had lower livability compared to the other treatments. Hens fed estimated-AA also laid smaller eggs compared to control and high-AA fed birds. Back feather cover deteriorated as hens grew older, and hens fed the estimated-AA diets had poorer feather cover from 41 wk onward. Overall, these results suggest that feeding higher AA levels than Aviagen recommendations presented no benefit in reproductive performance or feather quality. The estimated-AA feeding approach supported laying performance similar as other treatments, although affected egg weight and back feather cover.

Ultrasonographic screening for subclinical osteochondrosis of the femoral trochlea in foals (28-166 days old): a prospective farm study.

BACKGROUND: Extensive osteochondritis dissecans (OCD) lesions of the lateral ridge of the trochlea of the femur (LRTF), the most common OCD-affected site in the stifle, have a poor outcome with surgical debridement and can be career ending. The early detection of osteochondrosis lesions and their conservative management holds the promise to enhance outcome. We hypothesise that ultrasonography is a valuable field screening tool to detect and monitor early subclinical LRTF osteochondrosis. OBJECTIVES: The goals were to 1) describe the normal ultrasonographic features of the LRTF in foals of different ages and 2) screen a foal cohort at the farm for early subclinical osteochondrosis lesions. STUDY DESIGN: Prospective cohort study. METHODS: The LRTF of both hindlimbs of Thoroughbred foals (n = 46, 27-166 days old) were imaged once with ultrasonography and radiography (lateromedial and caudolateral-craniomedial oblique views). Cartilage thickness, ossification front indentation of the chondro-osseous junction and epiphyseal vascularisation were assessed on ultrasonography. Follow-up radiographs were taken as yearlings. RESULTS: The cartilage thickness, ossification front indentation and epiphyseal vascularisation significantly decreased with advancing maturity. Subclinical osteochondrosis lesions, characterised by semicircular indentations in the ossification front (indirect evidence of focal failure of ossification and retained cartilage) were detected in six foals (28-145 days old), both with radiography and ultrasonography. Ultrasonography provided a better overall subjective assessment of the osteochondrosis lesion topography (length, depth and the width) compared with radiography. MAIN LIMITATIONS: Post-mortem validation of lesions was not possible. CONCLUSION: Ultrasonography of the LRTF is a practical, inexpensive and reliable technique to discriminate physiological from pathological events at the LRTF in young foals. It revealed the complex topography of the chondro-osseous junction permitting a rapid, comprehensive assessment of the subclinical osteochondrosis lesions in very young foals.

Evaluation of starter dietary digestible lysine level on broilers raised under a sex-separated or straight-run housing regime, part 2: Economics of sex separation and digestible lysine level for maximum returns.

The objective of this experiment was to determine the maximum net returns digestible lysine (dLys) levels (MNRL) when maintaining the ideal amino acid ratio for starter diets of broilers raised sex separate or comingled (straight-run). A total of 3,240 Ross 708 chicks was separated by sex and placed in 90 pens by 2 rearing types: sex separate (36 males or 36 females) or straight-run (18 males + 18 females). Each rearing type was fed 6 starter diets (25 d) formulated to have dLys levels between 1.05 and 1.80%. A common grower diet with 1.02% of dLys was fed from 25 to 32 days. Body weight gain (BWG) and feed intake were assessed at 25 and 32 d for performance evaluation. Additionally, at 26 and 33 d, 4 birds per pen were sampled for carcass yield evaluation. Data were modeled using response surface methodology in order to estimate feed intake and whole carcass weight at 1,600 g live BW. Returns over feed cost were estimated for a 1.8-million-broiler complex of each rearing system under 9 feed/meat price scenarios. Results indicated that females needed more feed to reach market weight, followed by straight-run birds, and then males. At medium meat and feed prices, female birds had MNRL at 1.07% dLys, whereas straight-run and males had MNRL at 1.05%. As feed and meat prices increased, females had MNRL increased up to 1.15% dLys. Sex separation resulted in increased revenue under certain feed and meat prices, and before sex separation cost was deducted. When the sexing cost was subtracted from the returns, sex separation was not shown to be economically viable when targeting birds for light market BW.

Straight-run vs. sex separate rearing for two broiler genetic lines Part 2: Economic analysis and processing advantages.

The objective of this analysis was to evaluate the effects of raising broilers under sex separate and straight-run conditions for 2 broiler genetic lines. One-day-old Ross 308 and Ross 708 chicks (n = 1,344) were sex separated and placed in 48 pens according to rearing type: sex separate (28 males or 28 females) or straight-run (14 males + 14 females). There were 3 dietary phases: starter (zero to 17 d), grower (17 to 32 d), and finisher (32 to 48 d). Bird individual BW and group feed intakes were measured at 12, 17, 25, 32, 42, and 48 d to evaluate performance. At 33, 43, and 49 d 4 birds per pen (straight-run pens 2 males + 2 females) were sampled for carcass yield evaluation. Data were analyzed using linear and non-linear regression in order to estimate feed intake and cut-up weights at 3 separate market weights (1,700, 2,700, and 3,700 g). Returns over feed cost were estimated for a 1.8 million broiler complex for each rearing system and under 9 feed/meat price scenarios. Overall, rearing birds that were sex separated resulted in extra income that ranged from ${\$}$48,824 to ${\$}$330,300 per week, depending on the market targeted and feed and meat price scenarios. Sex separation was shown to be especially important in disadvantageous scenarios in which feed prices were high. Gains from sex separation were markedly higher for the Ross 708 than for the Ross 308 broilers. Bird variability also was evaluated at the 3 separate market ages under narrow ranges of BW that were targeted. Straight-run birds decreased the number of birds present in the desired range. Depending on market weight, straight-run rearing resulted in 9.1 to 16.6% fewer birds than sex separate rearing to meet marketing goals. It was concluded that sex separation can result in increased company profitability and have possible beneficial effects at the processing plant due to increased bird uniformity.

Straight-run vs. sex separate rearing for 2 broiler genetic lines Part 1: Live production parameters, carcass yield, and feeding behavior.

The objective of this experiment was to evaluate the effects of raising broilers under sex separate and straight-run conditions for 2 broiler strains. Day-old Ross 308 and Ross 708 chicks (n = 1,344) were separated by sex and placed in 48 pens according to the rearing type: sex separate (28 males or 28 females) or straight-run (14 males + 14 females). There were 3 dietary phases: starter (zero to 17 d), grower (17 to 32 d), and finisher (32 to 48 d). Birds' individual BW and feed intakes were measured at 12, 17, 25, 32, 42, and 48 d to evaluate performance. At 33, 43, and 49 d, 4 birds per pen were sampled for carcass yield evaluation. Additionally, from 06:00 to 06:30, 13:00 to 13:30, and 22:00 to 22:30, video records were taken to assess behavior at 45 days. Data were analyzed as CRD with a 2 × 3 factorial arrangement of treatments over time. Throughout the experiment Ross 308 were heavier than the 708, and after 17 d, male pens had the heavier birds, followed by straight-run and then females. Straight-run pens had higher BW CV in comparison with sex separate pens. Sex separate male BW was negatively impacted from 17 to 32 days. On the other hand, females raised sex separate were heavier than females raised straight-run with lower CV from 25 to 41 days. Post 25 d, FCR was the lowest in male pens whereas feed intake was the highest for these pens after 17 days. Overall, males had total carcass cut-up weights higher than straight-run and females at the 3 processing times. The Ross 708 had higher white meat yields, whereas 308 had higher yields for dark meat. Feeding behavior results were not consistent over time. However, from 13:00 to 13:30, birds in female pens spent more time eating, followed by straight-run and then males. In conclusion, raising females in a straight-run system negatively impacted performance and CV, whereas males benefited from straight-run rearing, with the differences being possibly related to feeder space competition.