Position of the Proximal Manica Flexoria under different grades of fetlock joint extension - A biomechanical observational study in the equine fore- and hindlimb.

OBJECTIVE: The aim of this study was to examine the position of the proximal manica flexoria and the proximal scutum under different grades of fetlock joint extension and to describe measurements and compare findings between equine fore- and hindlimbs. STUDY DESIGN: It was an observational study. RESULTS: During fetlock joint extension, the proximal manica flexoria and the proximal scutum displace distally relative to the palmar/plantar extent of the sagittal ridge of the cannon bone. The proximal manica flexoria is further displaced distal to the proximal scutum within the fetlock canal. No significant differences were identified between fore- and hindlimbs at different levels of fetlock joint extension. The proximal scutum was observed to be longer and thicker and the tendinous part of the manica flexoria was longer in forelimbs compared with hindlimbs. CONCLUSION AND CLINICAL RELEVANCE: The described findings contribute to the understanding of the pathogenesis of manica flexoria tearing. The fact that the proximal scutum and the tendinous part of the manica flexoria are shorter in the hindlimb might explain why the manica flexoria is more likely to get caught on the proximal aspect of the scutum and develop a tear in the equine hindlimb.

Elbow-joint morphology in the North American 'cheetah-like' cat Miracinonyx trumani.

The North American cheetah-like cat Miracinonyx trumani is an extinct species that roamed the Pleistocene prairies 13 000 years ago. Although M. trumani is more closely related to the cougar (Puma concolor) than to the living cheetah (Acinonyx jubatus), it is believed that both A. jubatus and M. trumani possess a highly specialized skeleton for fast-running, including limbs adapted for speed at the expense of restricting the ability of prey grappling. However, forelimb dexterity of M. trumani has not been yet investigated. Here, we quantify the 3D-shape of the humerus distal epiphysis as a proxy for elbow-joint morphology in a sample of living cats to determine whether the extinct M. trumani was specialized to kill open-country prey using predatory behaviour based on fast running across the prairies and steppe terrains of the North American Pleistocene. We show that M. trumani had an elbow morphology intermediate to that of P. concolor and A. jubatus, suggesting that M. trumani had a less specialized pursuit predatory behaviour than A. jubatus. We propose that M. trumani probably deployed a unique predatory behaviour without modern analogues. Our results bring into question the degree of ecomorphological convergence between M. trumani and its Old World vicar A. jubatus.

Morphological and radiological study of the shoulder and elbow joints of the giant anteater (Myrmecophaga tridactyla).

The giant anteater (Myrmecophaga tridactyla) has specialized thoracic limbs to forage by breaking the walls of anthills and termite mounds. They also play critical roles in defense posture and locomotion. This study aimed to provide a morphological and radiographic description of the shoulder joint and elbow joint of the giant anteater. Both joints of 13 tamanduas were assessed by morphological dissections and histological evaluation and radiographies without and with positive contrast. The radiographic projections selected to this study were the mediolateral and craniocaudal projections. The radiographic and anatomical findings were compared with the following results: the shoulder joint had a continuous joint capsule with the tendon sheaths of the short head and long head of the biceps brachii muscle, which could be visualized with an injection of 3 ml of intra-articular contrast. The shoulder joint arthrography was performed with the needle positioned cranially to the joint for contrast injection. The elbow joint presented three articular compartments, and the insertion of the joint capsule was proximal to the radial fossa and distal to the radial tuberosity in the radial notch of the ulna, which were possible to identify with 2 ml of intra-articular contrast. The elbow joint arthrography was performed with the needle positioned laterally to the joint for contrast injection. Moreover, the joint capsule presented a caudomedial distention and fat pads. The powerful muscles of the forelimb play a fundamental role in maintaining the shoulder joint and elbow joint stability due to bony adaptations and the absence of usual ligaments. The morphological and radiological study provided relevant information on the soft-tissue characteristics of shoulder and elbow joints, which may aid clinical-surgical and diagnostic imaging procedures.

Advances in Engineered Three-Dimensional (3D) Body Articulation Unit Models.

Indeed, the body articulation units, commonly referred to as body joints, play significant roles in the musculoskeletal system, enabling body flexibility. Nevertheless, these articulation units suffer from several pathological conditions, such as osteoarthritis (OA), rheumatoid arthritis (RA), ankylosing spondylitis, gout, and psoriatic arthritis. There exist several treatment modalities based on the utilization of anti-inflammatory and analgesic drugs, which can reduce or control the pathophysiological symptoms. Despite the success, these treatment modalities suffer from major shortcomings of enormous cost and poor recovery, limiting their applicability and requiring promising strategies. To address these limitations, several engineering strategies have been emerged as promising solutions in fabricating the body articulation as unit models towards local articulation repair for tissue regeneration and high-throughput screening for drug development. In this article, we present challenges related to the selection of biomaterials (natural and synthetic sources), construction of 3D articulation models (scaffold-free, scaffold-based, and organ-on-a-chip), architectural designs (microfluidics, bioprinting, electrospinning, and biomineralization), and the type of culture conditions (growth factors and active peptides). Then, we emphasize the applicability of these articulation units for emerging biomedical applications of drug screening and tissue repair/regeneration. In conclusion, we put forward the challenges and difficulties for the further clinical application of the in vitro 3D articulation unit models in terms of the long-term high activity of the models.

Homoplasy in the evolution of modern human-like joint proportions in Australopithecus afarensis.

The evolution of bipedalism and reduced reliance on arboreality in hominins resulted in larger lower limb joints relative to the joints of the upper limb. The pattern and timing of this transition, however, remains unresolved. Here, we find the limb joint proportions of Australopithecus afarensis, Homo erectus, and Homo naledi to resemble those of modern humans, whereas those of A. africanus, Australopithecus sediba, Paranthropus robustus, Paranthropus boisei, Homo habilis, and Homo floresiensis are more ape-like. The homology of limb joint proportions in A. afarensis and modern humans can only be explained by a series of evolutionary reversals irrespective of differing phylogenetic hypotheses. Thus, the independent evolution of modern human-like limb joint proportions in A. afarensis is a more parsimonious explanation. Overall, these results support an emerging perspective in hominin paleobiology that A. afarensis was the most terrestrially adapted australopith despite the importance of arboreality throughout much of early hominin evolution.

Computed tomographic and radiographic morphology of the pastern and coffin joints of One-Humped Camel (Camelus dromedarius).

The objective of the current study was to describe the structures of the pastern and coffin joints in dromedary camel using x-ray, bone and soft tissue windows computed tomography (CT) and three-dimensional volume rendering (3DVR) of CT imaging. 3DVR of CT was obtained at the slight flexed dorsal view, plantar view, dorsolateral view and lateral view which explained all the surfaces and structures of the digit bony parts even the parts of the articular surface. The processed images of 3DVR of CT showed different patterns of the cortical, cancellous, subchondral bones and medullary cavity of the bones of the digits. The present study showed clearly all the hard and soft tissues in the pastern and coffin joints of the camel in CT images; however, the plantar ligaments of the pastern joint and ligaments of the navicular cartilage identified on CT images. The CT soft tissue window visualized the joint cavity and their pouches and tendon sheath of the flexor tendons better than the bone window CT. The radiographic, CT and 3D images could be used as a normal reference for the interpretation of some clinical diseases in the pastern and coffin joints of the camel.

Kinematics and morphology: A comparison of 3D-patterns in the fifth pereiopod of swimming and non-swimming crab species (Malacostraca, Decapoda, Brachyura).

Swimming crabs of the taxon Portunoidea show specialized, paddle-shaped fifth pereiopods (P5), which play a role in these crabs' ability to swim. In this study, the morphology of the fifth pereiopod in swimming and non-swimming crabs was studied in detail and the mobility in the articulations between podomeres was calculated from reconstructed three-dimensional (3D)-models. This way, we aimed to provide new estimates of kinematic parameters, and to answer the question on a possible homology of the P5 within several portunoid clades. We measured and compared podomere length ratios, orientations of the joint axes, and modeled single range of motion (sROM) of each joint as well as the total range of motion (tROM) of all joints of the P5 as a whole. Seven Portunoidea species, four of them belonging to the P5-swimming crab morphotype (Liocarcinus depurator, Polybius henslowii, Callinectes sapidus, Portunus pelagicus) and three not belonging to this morphotype (Carcinus aestuarii, Portumnus latipes, and with uncertain status Carupa tenuipes) were compared with the non-portunoids Sternodromia monodi, Ranina ranina, Raninoides bouvieri, Eriocheir sinensis, Varuna litterata, Ashtoret lunaris, and Cancer pagurus. The study was carried out using a combination of microcomputer tomography (µCT)-techniques and 3D-reconstructions. The µCT-data were used to create surface models of the P5 in Amira, which were then 3D-animated and manipulated in Maya to qualitatively compare modeled kinematic parameters. Results show that the merus and carpus in swimming crabs are shorter than in non-swimming crabs, while sROM angles are generally larger. The tROM of all joints expressed as Euclidean distances is generally higher in the portunoids (except for Carcinus). Our comparison of the complete trajectory of the dactylus tip regarding all maximum joint positions of the studied species suggests that the P5-swimming leg might have evolved once in the Portunoidea and got lost afterward in certain clades.

Distraction index measurement on the dog's hip joint using a dedicated software / [Medição do índice de distração da anca do cão usando um software especial]

The aim of this study was to test the accuracy of a new automated computer software tool for the assessment of passive hip laxity. The hip laxity was estimated using the dedicated computer software by two blinded evaluators, one previously trained and one without specific training for distraction index measurement, in two independent sessions using 230 hip joints from 115 dogs that underwent screening for passive hip laxity using the distraction view. Previously, all of these radiographs were sent to PennHIP Analysis Center for an official distraction index record. The measurement repeatability of the two sessions was adequate for both evaluators. The reproducibility of the official distraction index measurement, mean distraction index±standard deviation 0.44±0.15, was adequate (P>0.05) for the trained evaluator, 0.44±0.15, and non-adequate (P<0.05), for the non-trained evaluator 0.47±0.17. The distraction index measurement tool proposed can be used with confidence for hip laxity evaluation by trained evaluators, as it provided good repeatability and reproducibility of official reports. The simplicity of the process described leads to a less time-consuming and more affordable procedure.(AU)

O objetivo deste estudo foi testar a viabilidade de uma nova ferramenta de software informático para avaliação da lassitude articular passiva da articulação coxofemoral. A lassitude articular da articulação coxofemoral foi estimada usando-se um programa informático especial, desenvolvido para o efeito, por dois avaliadores, um com treino prévio e outro não treinado, na medição do índice de distração, em duas sessões independentes, utilizando-se 230 articulações coxofemorais de 115 cães, as quais efetuaram o rastreio de displasia coxofemoral realizando a projeção de distração da articulação coxofemoral. Previamente, todas as radiografias foram enviadas para o PennHIP Analysis Center, para se obter uma medida oficial do índice de distração. A repetibilidade das medições das duas sessões foi adequada para ambos os avaliadores. A reprodutibilidade do índice de distração oficial, média±desvio-padrão 0,44±0,15, foi adequada (P>0,05) para o avaliador treinado, 0,44±0,15, e não adequada (P>0,05) para o avaliador não treinado, 0,47±0,17. A ferramenta de medição do índice de distração proposta pode ser usada com segurança na medição do índice de distração por avaliadores treinados, uma vez que mostra uma adequada repetibilidade e reprodutibilidade das medições oficiais do índice de distração. A simplicidade do processo apresentado torna-o menos demorado e mais econômico.(AU)

[Computed tomography based elbow joint morphology and incidence of elbow dysplasia in the red fox (Vulpes vulpes)]. / Computertomografische Morphologie des Ellbogengelenks und Vorkommen der Ellbogengelenkdysplasie beim Rotfuchs (Vulpes vulpes).

OBJECTIVE: Elbow dysplasia (ED) is a common developmental disease of the canine elbow joint and one of the most frequent causes of forelimb lameness in domestic dogs (Canis lupus familiaris). ED is predominantly present in medium to large breed dogs, but has also been described in mixed breed dogs and smaller breeds. In the literature, no information is available concerning the existence of ED in wildlife species. The purpose of the present study was to obtain an overview of the elbow joint anatomy of the red fox as well as to demonstrate the incidence of ED in red foxes. Knowledge regarding the elbow conformation in red foxes may help to understand the effect of anatomical difference onto the pathogenesis of developmental elbow disease. MATERIAL AND METHODS: A total 94 elbow joints of 49 red foxes (Vulpes vulpes) were evaluated using computed tomography (CT) and were compared to canine elbow joints. RESULTS: Apart from size differences and minor species-specific variations, the anatomy of the elbow joints of red foxes and domestic dogs proved to be very similar. In the red foxes, the rounded conformation of the medial coronoid process was shown to be present in 76 % of the individuals. Two elbow joints in 2 red foxes exhibited pathological changes of the medial coronoid process in the CT imaging. CONCLUSION: The prevalence of medial coronoid disease in red foxes amounted to 2.1 % in the presented population. This observation is comparable to the prevalence of elbow dysplasia in small breed dogs. The rounded conformation of the medial coronoid process was found in more than three-quarters of the examined red foxes. This leads to the hypothesis that this conformation of the medial coronoid process could be the original, physiological variant. Selective breeding for such a morphological feature may be an approach to reduce the frequency of canine elbow dysplasia. CLINICAL RELEVANCE: The significance of anatomical characteristics in the development of elbow dysplasia is still unknown. Therefore, research concerning the pathogenesis of medial coronoid disease should set its focus not only on elbow joint anatomy, but also on other influencing factors, such as biomechanics, genetics and environmental parameters.

Mandibular symphyseal fusion in fossil primates: Insights from correlated patterns of jaw shape and masticatory function in living primates.

OBJECTIVES: Variation in primate masticatory form and function has been extensively researched through both morphological and experimental studies. As a result, symphyseal fusion in different primate clades has been linked to either the recruitment of vertically directed balancing-side muscle force, the timing and recruitment of transversely directed forces, or both. This study investigates the relationship between jaw muscle activity patterns and morphology in extant primates to make inferences about masticatory function in extinct primates, with implications for understanding the evolution of symphyseal fusion. MATERIALS AND METHODS: Three-dimensional mandibular landmark data were collected for 31 extant primates and nine fossil anthropoids and subfossil lemur species. Published electromyography (EMG) data were available for nine of the extant primate species. Partial least squares analysis and phylogenetic partial least squares analysis were used to identify relationships between EMG and jaw shape data and evaluate variation in jaw morphology. RESULTS: Primates with partial and complete symphyseal fusion exhibit shape-function patterns associated with the wishboning motor pattern and loading regime, in contrast to shape-function patterns of primates with unfused jaws. All fossil primates examined (except Apidium) exhibit jaw morphologies suggestive of the wishboning motor pattern demonstrated in living anthropoids and indriids. DISCUSSION: Partial fusion in Catopithecus, similar to indriids and some subfossil lemurs, may be sufficient to resist, or transfer, some amounts of transversely directed balancing-side muscle force at the symphysis, representing a transition to greater reliance on transverse jaw movement during mastication. Furthermore, possible functional convergences in physiological patterns during chewing (i.e., Archaeolemur) are identified.

Weakly Supervised Adversarial Learning for 3D Human Pose Estimation from Point Clouds.

Point clouds-based 3D human pose estimation that aims to recover the 3D locations of human skeleton joints plays an important role in many AR/VR applications. The success of existing methods is generally built upon large scale data annotated with 3D human joints. However, it is a labor-intensive and error-prone process to annotate 3D human joints from input depth images or point clouds, due to the self-occlusion between body parts as well as the tedious annotation process on 3D point clouds. Meanwhile, it is easier to construct human pose datasets with 2D human joint annotations on depth images. To address this problem, we present a weakly supervised adversarial learning framework for 3D human pose estimation from point clouds. Compared to existing 3D human pose estimation methods from depth images or point clouds, we exploit both the weakly supervised data with only annotations of 2D human joints and fully supervised data with annotations of 3D human joints. In order to relieve the human pose ambiguity due to weak supervision, we adopt adversarial learning to ensure the recovered human pose is valid. Instead of using either 2D or 3D representations of depth images in previous methods, we exploit both point clouds and the input depth image. We adopt 2D CNN to extract 2D human joints from the input depth image, 2D human joints aid us in obtaining the initial 3D human joints and selecting effective sampling points that could reduce the computation cost of 3D human pose regression using point clouds network. The used point clouds network can narrow down the domain gap between the network input i.e. point clouds and 3D joints. Thanks to weakly supervised adversarial learning framework, our method can achieve accurate 3D human pose from point clouds. Experiments on the ITOP dataset and EVAL dataset demonstrate that our method can achieve state-of-the-art performance efficiently.

Non-uniformity of displacement and strain within the Achilles tendon is affected by joint angle configuration and differential muscle loading.

Although the Achilles tendon (AT) has been studied for more than a century, a complete understanding of the mechanical and functional consequences of AT structural organization is currently lacking. The aim of this study was to assess how joint angle configuration affects subtendon displacement and strain of soleus (SOL) and lateral gastrocnemius (LG) muscles. Knots sutured onto SOL and LG subtendons of 12 Wistar rats, were videotaped to quantify displacements and the ankle torque was assessed for different isometric activation conditions (i.e., individual and simultaneous) of the triceps surae muscles. Changing ankle and knee joint angle affected the magnitude of displacement, relative displacement and strain of both SOL and LG subtendons. SOL subtendon behavior was not only affected by changes in ankle angle, but also by changes in knee angle. Displacement of SOL subtendon decreased (28-49%), but strain increased in response to knee extension. Independent of joint angle configuration, stimulation of any combination of the muscles typically resulted in displacements and strains of LG and SOL subtendons. Typically SOL displaced more but LG displaced more when stimulated at longer muscle lengths. Our results demonstrate that the distinct subtendons of the Achilles tendon can move and deform differently, but are not fully independent. Within the AT, there appears to be a precarious balance between sliding allowance and mechanical connectivity between subtendons.

Normal anatomic reference of pastern and coffin joints in Egyptian buffalo (Bubalus bubalis): A compared atlas of cross-sectional anatomy, magnetic resonance imaging and computed tomography.

The purpose of this study was to describe normal magnetic resonance imaging and computed tomographic anatomy of pastern and coffin joints in Egyptian buffalo using cadaveric distal limbs. This study was achieved using twelve fresh cadaveric distal limbs from adult healthy buffaloes of both sexes. These cadaveric limbs were scanned using a 1 Tesla MRI scanner and CT scanner, injected with red latex, frozen at -20°C for 1 week, and then sectioned into sagittal, dorsal and transverse slices. The obtained MR and CT images were selected to be matched with their corresponding anatomical cross-sections for identification and evaluation of the clinically correlated anatomical structures of the pastern and coffin joints. The difference in signal intensities on CT and MRI scans amongst the tissues allowed clear differentiation of major bone and soft tissue structures of the pastern and coffin joints. CT provided a high spatial resolution of bone and soft tissue structures, however, MRI allowed a better and higher resolution and definition between soft tissues. The current study provided a normal CT and MRI anatomic reference which could help veterinary clinicians for interpretation and diagnosis of the clinically affected pastern and coffin joints in buffalo.

"All models are wrong, but some are useful": On the non-bayesianstatistical robustness of Hilton's law

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Computational model of a synovial joint morphogenesis.

Joints enable the relative movement between the connected bones. The shape of the joint is important for the joint movements since they facilitate and smooth the relative displacement of the joint's parts. The process of how the joints obtain their final shape is yet not well understood. Former models have been developed in order to understand the joint morphogenesis leaning only on the mechanical environment; however, the obtained final anatomical shape does not match entirely with a realistic geometry. In this study, a computational model was developed with the aim of explaining how the morphogenesis of joints and shaping of ossification structures are achieved. For this model, both the mechanical and biochemical environments were considered. It was assumed that cartilage growth was controlled by cyclic hydrostatic stress and inhibited by octahedral shear stress. In addition, molecules such as PTHrP and Wnt promote chondrocyte proliferation and therefore cartilage growth. Moreover, the appearance of the primary and secondary ossification centers was also modeled, for which the osteogenic index and PTHrP-Ihh concentrations were taken into account. The obtained results from this model show a coherent final shape of an interphalangeal joint, which suggest that the mechanical and biochemical environments are crucial for the joint morphogenesis process.

The roles of joint tissues and jaw muscles in palatal biomechanics of the savannah monitor (Varanus exanthematicus) and their significance for cranial kinesis.

Numerous vertebrates exhibit cranial kinesis, or movement between bones of the skull and mandible other than at the jaw joint. Many kinetic species possess a particular suite of features to accomplish this movement, including flexible cranial joints and protractor musculature. Whereas the musculoskeletal anatomy of these kinetic systems is well understood, how these joints are biomechanically loaded, how different soft tissues affect joint loading and kinetic capacity, and how the protractor musculature loads the skull remain poorly understood. Here, we present a finite element model of the savannah monitor, Varanus exanthematicus, a modestly kinetic lizard, to better elucidate the roles of soft tissue in mobile joints and protractor musculature in cranial loading. We describe the 3D resultants of jaw muscles and the histology of palatobasal, otic and jaw joints. We tested the effects of joint tissue type, bite point and muscle load to evaluate the biomechanical role of muscles on the palate and braincase. We found that the jaw muscles have significant mediolateral components that can impart stability across palatocranial joints. Articular tissues affect the magnitude of strains experienced around the palatobasal and otic joints. Without protractor muscle loading, the palate, quadrate and braincase experience higher strains, suggesting this muscle helps insulate the braincase and palatoquadrate from high loads. We found that the cross-sectional properties of the bones of V. exanthematicus are well suited for performing under torsional loads. These findings suggest that torsional loading regimes may have played a more important role in the evolution of cranial kinesis in lepidosaurs than previously appreciated.

Real-Time Magnetic Resonance Imaging: Radial Gradient-Echo Sequences With Nonlinear Inverse Reconstruction.

OBJECTIVE: The aim of this study is to evaluate a real-time magnetic resonance imaging (MRI) method that not only promises high spatiotemporal resolution but also practical robustness in a wide range of scientific and clinical applications. MATERIALS AND METHODS: The proposed method relies on highly undersampled gradient-echo sequences with radial encoding schemes. The serial image reconstruction process solves the true mathematical task that emerges as a nonlinear inverse problem with the complex image and all coil sensitivity maps as unknowns. Extensions to model-based reconstructions for quantitative parametric mapping further increase the number of unknowns, for example, by adding parameters for phase-contrast flow or T1 relaxation. In all cases, an iterative numerical solution that minimizes a respective cost function is achieved with use of the iteratively regularized Gauss-Newton method. Convergence is supported by regularization, for example, to the preceding frame, whereas temporal fidelity is ensured by downsizing the regularization strength in comparison to the data consistency term in each iterative step. Practical implementations of highly parallelized algorithms are realized on a computer with multiple graphical processing units. It is "invisibly" integrated into a commercial 3-T MRI system to allow for conventional usage and to provide online reconstruction, display, and storage of regular DICOM image series. RESULTS: Depending on the application, the proposed method offers serial imaging, that is, the recording of MRI movies, with variable spatial resolution and up to 100 frames per second (fps)-corresponding to 10 milliseconds image acquisition times. For example, movements of the temporomandibular joint during opening and closing of the mouth are visualized with use of simultaneous dual-slice movies of both joints at 2 × 10 fps (50 milliseconds per frame). Cardiac function may be studied at 30 to 50 fps (33.3 to 20 milliseconds), whereas articulation processes typically require 50 fps (20 milliseconds) or orthogonal dual-slice acquisitions at 2 × 25 fps (20 milliseconds). Methodological extensions to model-based reconstructions achieve improved quantitative mapping of flow velocities and T1 relaxation times in a variety of clinical scenarios. CONCLUSIONS: Real-time gradient-echo MRI with extreme radial undersampling and nonlinear inverse reconstruction allows for direct monitoring of arbitrary physiological processes and body functions. In many cases, pertinent applications offer hitherto impossible clinical studies (eg, of high-resolution swallowing dynamics) or bear the potential to replace existing MRI procedures (eg, electrocardiogram-gated cardiac examinations). As a consequence, many novel opportunities will require a change of paradigm in MRI-based radiology. At this stage, extended clinical trials are needed.

Angles and waves: intervertebral joint angles and axial kinematics of limbed lizards, limbless lizards, and snakes.

Segmentation gives rise to the anterior-posterior axis in many animals, and in vertebrates this axis comprises serially arranged vertebrae. Modifications to the vertebral column abound, and a recurring, but functionally understudied, change is the elongation of the body through the addition and/or elongation of vertebrae. Here, we compared the vertebral and axial kinematics of the robustly limbed Fire skink (Riopa fernandi) representing the ancestral form, the limbless European glass lizard (Ophisaurus apodus), and the Northern water snake (Nerodia sipedon). We induced these animals to traverse through channels and peg arrays of varied widths and densities, respectively, using high-speed X-ray and light video. We found that even though the snake had substantially more and shorter vertebrae than either lizard, intervertebral joint angles did not differ between species in most treatment levels. All three species decreased the amplitude and wavelength of their undulations as channels narrowed and the lizard species increased wave frequency in narrower channels. In peg arrays, both lizard species decreased wave amplitude, while the snake showed no differences. All three species maintained similar wavelengths and frequencies as peg density increased in most cases. Our results suggest that amplitude is decoupled from wavelength and frequency in all three focal taxa. The combination of musculoskeletal differences and the decoupling of axial kinematic traits likely facilitates the formation of different undulatory waves, thereby allowing limbless species to adopt different modes of locomotion.

High-Resolution, Wide-Field, Forward-Viewing Spectrally Encoded Endoscope.

BACKGROUND AND OBJECTIVE: Spectrally encoded endoscopy (SEE) is an optical imaging technology that uses spatial wavelength multiplexing to conduct endoscopy in miniature, small diameter probes. Contrary to the previous side-viewing SEE devices, forward-viewing SEE probes are advantageous as they provide a look ahead that facilitates navigation and surveillance. The objective of this work was to develop a miniature forward-viewing SEE probe with a wide field of view and a high spatial resolution. MATERIALS AND METHODS: We designed and developed a forward-viewing SEE device with an overall total diameter of 1.27 mm, which consists of a monolithic illumination probe with a length of 3.87 mm and a diameter of 500 µm, 8 multimode detection fibers that were polished at a 17° angle, a rotational scanning mechanism, and a sheath. The SEE device was evaluated using a USAF resolution target and was used for preclinical imaging of a swine joint ex vivo. RESULTS: This design resulted in a high resolution probe (best spatial resolution of 20.3 µm), a wide total angular field of view of 100°, and an effective number of imaging elements of ~344,000 pixels. The SEE probe performance was compared to a commercial color chip-on-the-tip endoscope; while monochrome, results showed better spatial resolution and a wider field of view for the SEE device. CONCLUSION: These results demonstrate the potential of this forward-viewing SEE probe for visualization and navigation in medical imaging applications. Lasers Surg. Med. © 2019 Wiley Periodicals, Inc.

Genome-Wide Association Studies Based on Equine Joint Angle Measurements Reveal New QTL Affecting the Conformation of Horses.

The evaluation of conformation traits is an important part of selection for breeding stallions and mares. Some of these judged conformation traits involve joint angles that are associated with performance, health, and longevity. To improve our understanding of the genetic background of joint angles in horses, we have objectively measured the angles of the poll, elbow, carpal, fetlock (front and hind), hip, stifle, and hock joints based on one photograph of each of the 300 Franches-Montagnes (FM) and 224 Lipizzan (LIP) horses. After quality control, genome-wide association studies (GWASs) for these traits were performed on 495 horses, using 374,070 genome-wide single nucleotide polymorphisms (SNPs) in a mixed-effect model. We identified two significant quantitative trait loci (QTL) for the poll angle on ECA28 (p = 1.36 × 10-7), 50 kb downstream of the ALX1 gene, involved in cranial morphology, and for the elbow joint on ECA29 (p = 1.69 × 10-7), 49 kb downstream of the RSU1 gene, and 75 kb upstream of the PTER gene. Both genes are associated with bone mineral density in humans. Furthermore, we identified other suggestive QTL associated with the stifle joint on ECA8 (p = 3.10 × 10-7); the poll on ECA1 (p = 6.83 × 10-7); the fetlock joint of the hind limb on ECA27 (p = 5.42 × 10-7); and the carpal joint angle on ECA3 (p = 6.24 × 10-7), ECA4 (p = 6.07 × 10-7), and ECA7 (p = 8.83 × 10-7). The application of angular measurements in genetic studies may increase our understanding of the underlying genetic effects of important traits in equine breeding.