Article

Sire evaluation and herd level of milk production

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Abstract

Age-corrected milk records of 40,374 Holstein cows tested in 1,073 herds in Ontario were studied to determine if the level of herd production had an effect on the genetic expression of milk production. Heritability of milk production was estimated from paternal half-sib correlations at each of seven levels of herd production. The estimates obtained varied from 0.24 ± 0.05 to 0.36 ± 0.04, lowest values being associated with the lowest and highest levels of production. A significant quadratic component (P = 0.07) was obtained when these estimates were regressed on herd level of production. The sire component of variance increased from low to higher levels of herd production. The environmental component of variance increased in magnitude from the lowest to the highest production level, with a large increase at the highest level. Correlations among the contemporary comparison proofs of 19 sires, each evaluated on the production of 20 or more daughters at four levels of herd production, ranged from 0.73 to 1.01, indicating little change in ranking of sires across herd level of production.

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Article
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Article
To investigate the magnetic resonance (MR) imaging appearance of a chronically stressed wrist and to assess the utility of MR imaging for evaluation of injuries to the growth plate. Coronal T1-weighted spin-echo and gradient-echo MR images were obtained of 93 wrists in 47 high-risk gymnasts of a Chinese opera school. MR imaging and radiographic findings were correlated in 93 wrists. The major MR imaging abnormalities of 47 radii with abnormal radiographic findings were horizontal fractures (n = 23), physeal cartilage extension to metaphysis (n = 17), and physeal widening (n = 17). The major MR abnormalities of 46 radii with normal radiographs included physeal cartilage extension (n = 12), metaphyseal bone bruise (n = 8), and vertical fractures (n = 4). Physeal cartilage extension into the metaphysis represents a healing sign in chronically stressed adolescent wrists. MR imaging findings including horizontal fracture and physeal cartilage extension to the metaphysis suggest that physeal widening occurred secondary to metaphyseal injury.
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To offer a descriptive review which characterizes and evaluates the significance of local physeal widening, (cartilaginous signal extending from the physis into the adjacent metaphysis), identified on magnetic resonance (MR) imaging. MR images (recollected from exams performed between 1988 and 1995) of 31 metaphyses in 22 children where we recognized local physeal widening were examined retrospectively. These areas of physeal widening were evaluated for morphology, depth, location, signal intensity, and the coexistence of epiphyseal alterations. The characteristics of the signal abnormalities were correlated with the duration and type of any identifiable insult to the adjacent metaphysis, and with the development of growth disturbance. Twenty-six metaphyses had identifiable insults (19 single event and 7 sustained or repetitive). The widened physes were of focal tongue (n = 15), broad band (n = 10), or mixed (n = 6) morphology. Most (n = 27) areas of widening were isointense with the physeal cartilage on all sequences. Subsequent growth disturbance was more likely when the metaphyseal insult was a single event rather than sustained or repetitive (P = 0.023), with focal tongues (P = 0.029), and with centrally located lesions (P = 0.030). In five cases, the adjacent epiphysis showed signal abnormalities; all developed growth disturbance. Histologic examinations available in two limbs confirmed that the MR findings represented extensions of hypertrophic physeal chondrocytes into the metaphysis. Incidentally observed local physeal widening in a growing bone may represent the imprint of a previous or ongoing interference with endochondral ossification from a prior metaphyseal insult, rather than a primary metaphyseal disorder. Single event insults, physeal widening of focal tongue morphology, central distribution in the metaphysis, and concomitant epiphyseal signal abnormalities on MR imaging are significant predictors of subsequent growth disturbance.
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The pathologic changes at the physis in patients with rickets have been well demonstrated histologically. Radiographs can depict only the associated osseous abnormalities. We report two children in whom MR imaging demonstrated rachitic changes in the physeal cartilage beyond the well-recognized bony features. The striking appearance of the physes and the physes of the secondary ossification centers confirm that MR imaging can successfully evaluate the cartilaginous structures of the developing skeleton. Though MR imaging is clearly unnecessary for the diagnosis of rickets, it is important that the typical features are not misinterpreted as other pathology.
Article
Despite substantial knowledge on the clinicopathology of chondrogenic skeletal neoplasms, only limited insights into the biology of the different tumor variants are available. There are virtually no established molecular markers for identification and classification of these neoplasms. In this paper, we present a systematic review of the biochemistry and cell biology of chondrogenic neoplasms of the bone focussing on our own recent investigations. The hallmark of all differentiated chondrogenic tumors is the presence of neoplastic chondrocytic cells responsible for the formation of the characteristic cartilaginous tumor matrix. These cells can show the full differentiation potential of physiologic chondrocytes depending on the tumor entity investigated. The high phenotypic diversity of physiologic chondrocytes explains the previously poorly understood, striking heterogeneity of the neoplastic cells and their surrounding extracellular matrix not only between different but also within chondrogenic tumors. In our studies, tumor classifications, so far based only on histomorphological criteria, were either confirmed or corrected: mesenchymal chondrosarcomas represent the prototypic neoplasm of pre-chondrogenic undifferentiated cells undergoing multifocal chondrocytic differentiation. Enchondromas, osteochondromas, and conventional chondrosarcomas are neoplasms of multi-phenotypically differentiated chondrocytes. Clear cell chondrosarcomas appear to be neoplasms of hypertrophic chondrocytic cells. A peculiar biology is displayed by dedifferentiated chondrosarcomas, which at least in most cases show neither "anaplasia" nor "dedifferentiation", but most likely "transdifferentiation" of part of the neoplastic cells to a cellular phenotype of a different mesenchymal differentiation lineage. Chondroblastomas do not show any chondroblastic differentiation at all. Our studies delineate molecular markers of chondrogenic neoplasms of the skeleton, which have the potential to be the basis of a new biology-orientated classification of skeletal neoplasms. The expression analysis of extracellular matrix genes, in particular of the collagen types, might be able to play herein a leading role in classification and diagnosis, similar to the cytokeratin subtypes or the CDs (cluster of differentiation) for the classification and diagnosis of neoplasms of the epithelia and the lymphatics.
Article
Rickets and the decreased ossification associated with it can give rise to abnormally low bone density and weakened osseous structures. Despite this association, rickets has rarely been associated with osteochondral defects, and the imaging findings of this association have not been previously described on magnetic resonance (MR) imaging. This case report presents an adolescent male with a clinical history of rickets and recent-onset knee pain that was determined to be caused by bilateral osteochondritis dissecans. Prompt recognition of osteochondritis dissecans is important, as this entity is a treatable cause of knee pain.
Article
Objective: The objective of our study was to describe the MRI appearance of and possible mechanism responsible for physeal widening in the knees of high-level child athletes. Conclusion: Widened physes in the knees of skeletally immature child athletes have MR signal characteristics similar to the normal physis but likely are a sign of stress injury. These children should cease the offending sport and rest the knee to allow rapid healing.
Article
The knee joint remains the articulation most frequently assessed by MR imaging, and osseous tumor and tumor-like lesions are not uncommon incidental imaging findings. This article reviews the most commonly encountered incidental lesions, emphasizing the characteristic MR imaging features. It is intended not as a complete review of the imaging findings associated with these lesions but as a summary, highlighting the MR imaging features that are most useful in suggesting a specific diagnosis. The authors organize incidental lesions into the following broad categories: cartilaginous, fibro-osseous, and degenerative. They do not address those lesions that are typically symptomatic and, as a result, likely to be directly related to the patients' clinical presentation and subsequent imaging.
Article
The purpose of our study was to determine the prevalence of incidental enchondromas on routine MR knee imaging. We retrospectively reviewed 449 consecutive routine knee MR examinations for the presence of enchondromas. MRI was considered positive when a focal geographic area of lobular marrow replacement (nonsubchondral) was identified on T1 weighting and high signal intensity was seen on T2 weighting. Patients with enchondromas were further evaluated for demographics; lesion site, size, and relationship to the physeal plate; aggressive imaging features described with chondrosarcoma; concurrent internal derangement; and study indication. The prevalence of incidental enchondromas was 2.9% on routine knee MR examinations. The prevalence was highest in the distal femur (2.0%), followed by the proximal tibia (0.7%) and the proximal fibula (0.2%). The average lesion size was 1.9 x 1.2 x 1.3 cm (57% of lesions were < 1 cm). Most lesions were located in the metaphysis (71%) or diaphysis (21%). Enchondromas were within 1.5 cm of the physeal plate in 72% of cases. No aggressive imaging features to suggest chondrosarcoma were seen. All patients had evidence of internal derangement as the cause of symptoms and the request for imaging. Incidental enchondromas can be identified on 2.9% of routine MR knee examinations, most frequently in the distal femur (2.0%). This significant prevalence is much higher than in an autopsy series (0.2%), likely reflecting the increased sensitivity of MRI for detecting small lesions, and is important to recognize to avoid confusion with other pathologic entities.
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