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Journal of Morphology Sep 2017A variety of vertebral centrum morphologies have evolved within early tetrapods which range from multipartite centra consisting of intercentra and pleurocentra in...
A variety of vertebral centrum morphologies have evolved within early tetrapods which range from multipartite centra consisting of intercentra and pleurocentra in stem-tetrapods, temnospondyls, seymouriamorphs, and anthracosaurs up to monospondylous centra in lepospondyls. With the present study, we aim to determine the formation of both intercentrum and pleurocentrum and asked whether these can be homologized based on their bone histology. Both intercentra and pleurocentra ossified endochondrally and periosteal bone was subsequently deposited on the outer surface of the centra. Our observations indicate low histological variation between intercentrum and pleurocentrum in microstructural organization and growth which inhibits the determination of homologies. However, intercentrum and pleurocentrum development differs during ontogeny. As previously assumed, the intercentrum arises from ventrally located and initially paired ossification centers that fuse ventromedially to form the typical, crescentic, rhachitomous intercentrum. In contrast, presacral pleurocentra may be ancestrally represented by four ossification centers: a ventral and a dorsal pair. Subsequently, two divergent developmental patterns are observed: In stem-tetrapods and temnospondyls, the pleurocentrum evolves from the two dorsally located ossification centers which may occasionally fuse to form a dorsal crescent. In some dvinosaurian temnospondyls, the pleurocentrum may even ossify to full rings. In comparison, the pleurocentrum of stem-amniotes (anthracosaurs, chroniosuchids, seymouriamorphs, and lepospondyls) arises from the two ventrally located ossification centers whereby the ossification pattern is almost identical to that of temnospondyls but mirror-inverted. Thus, the ring-shaped pleurocentrum of Discosauriscus ossifies from ventral to dorsal. We also propose that the ossified portions of the intercentrum and pleurocentrum continued as cartilaginous rings or discs that surrounded the notochord in the living animals.
Topics: Animals; Paleontology; Phylogeny; Vertebrates
PubMed: 28517044
DOI: 10.1002/jmor.20709 -
Developmental Neurobiology May 2015The basic organization of somatosensory circuits in the spinal cord is already setup during the initial patterning of the dorsal neural tube. Extrinsic signals, such as...
The basic organization of somatosensory circuits in the spinal cord is already setup during the initial patterning of the dorsal neural tube. Extrinsic signals, such as Wnt and TGF-β pathways, activate combinatorial codes of transcription factors that are responsible for generating a pattern of discrete domains of dorsal progenitors (dp). These progenitors will give rise to distinct dorsal interneurons (dI). The Wnt/ βcatenin signaling pathway controls specification of dp/dI1-3 progenitors and interneurons. According to the current model in the field, Wnt/βcatenin activity seems to act in a graded fashion in the spinal cord, as different relative levels determine the identity of adjacent progenitors. However, it is not clear how this activity gradient is controlled and how the identities of dI1-3 are differentially regulated by Wnt signalling. We have determined that two SoxD transcription factors, Sox5 and Sox6, are expressed in restricted domains of dorsal progenitors in the neural tube. Using gain- and loss-of function approaches in chicken embryos, we have established that Sox5 controls cell fate specification of dp2 and dp3 progenitors and, as a result, controls the correct number of the corresponding dorsal interneurons (dI2 and dI3). Furthermore, Sox5 exerts its function by restricting dorsally Wnt signaling activity via direct transcriptional induction of the negative Wnt pathway regulator Axin2. By that way, Sox5 acts as a Wnt pathway modulator that contributes to sharpen the dorsal gradient of Wnt/βcatenin activity to control the distinction of two functionally distinct types of interneurons, dI2 and dI3 involved in the somatosensory relay.
Topics: Animals; Avian Proteins; Cell Differentiation; Chick Embryo; Chickens; Gene Expression Regulation, Developmental; Interneurons; SOXD Transcription Factors; Signal Transduction; Spinal Cord; Stem Cells; Wnt Proteins
PubMed: 25363628
DOI: 10.1002/dneu.22240 -
PloS One 2024Predating Darwin's theory of evolution, the holotype of Saurodesmus robertsoni is a long-standing enigma. Found at the beginning of 1840s, the specimen is a damaged...
Predating Darwin's theory of evolution, the holotype of Saurodesmus robertsoni is a long-standing enigma. Found at the beginning of 1840s, the specimen is a damaged stylopodial bone over decades variably assigned to turtles, archosaurs, parareptiles, or synapsids, and currently nearly forgotten. We redescribe and re-assess that curious specimen as a femur and consider Saurodesmus robertsoni as a valid taxon of a derived cynodont (?Tritylodontidae). It shares with probainognathians more derived than Prozostrodon a mainly medially oriented lesser trochanter and with the clade reuniting tritylodontids, brasilodontids, and mammaliaforms (but excluding tritheledontids) the presence of a projected femoral head, offset from the long axis of the femoral shaft; a thin, plate-like greater trochanter; a distinct dorsal eminence proximal to the medial (tibial) condyle located close to the level of the long axis of the femoral shaft and almost in the middle of the width of the distal expansion; and a pocket-like fossa proximally to the medial (tibial) condyle. Saurodesmus robertsoni is most similar to tritylodontids, sharing at least with some forms: the relative mediolateral expansion of the proximal and distal regions of the femur, the general shape and development of the greater trochanter, the presence of a faint intertrochanteric crest separating the shallow intertrochanteric and adductor fossae, and the general outline of the distal region as observed dorsally and distally. This makes Saurodesmus robertsoni the first Triassic cynodont from Scotland and, possibly, one of the earliest representatives of tritylodontids and one of the latest non-mammaliaform cynodonts worldwide. Moreover, it highlights the need for revisiting historical problematic specimens, the identification of which could have been previously hampered by the lack of adequate comparative materials in the past.
Topics: Animals; Fossils; Femur; Scotland; Biological Evolution; Phylogeny
PubMed: 38809839
DOI: 10.1371/journal.pone.0303973 -
Cureus May 2020A 19-year-old female presented with pain, deformity, and slightly restricted left wrist motion for five years with gradual progression. Physical examination revealed...
A 19-year-old female presented with pain, deformity, and slightly restricted left wrist motion for five years with gradual progression. Physical examination revealed volar subluxation of the left hand, dorsally prominent ulnar styloid, radial and dorsal bowing of the distal forearm, and mild restriction in wrist dorsiflexion. Radiographs showed a failure of ossification of the ulnar side of the distal radial epiphysis, increased radial inclination angle, dorsal subluxation of the distal ulna, V-shaped proximal carpal row due to proximal migration of the lunate, and increased interosseous space. A diagnosis of Madelung deformity of the left wrist was made. Conservative management with oral analgesics, activity restriction, and a volar splint was done as the patient was skeletally mature, had only mild pain with no functional limitation or gross deformity. At the six-month follow-up, she was doing well with decreased pain and no new complaints.
PubMed: 32582486
DOI: 10.7759/cureus.8225 -
Joint Diseases and Related Surgery 2023The aim of this study was to evaluate the relationship between the length of the protruded screws from the dorsal cortex and extensor tendon damage in all compartments.
OBJECTIVES
The aim of this study was to evaluate the relationship between the length of the protruded screws from the dorsal cortex and extensor tendon damage in all compartments.
PATIENTS AND METHODS
Between May 2020 and April 2021, a total of 29 patients (13 males, 16 females; mean age: 52.3±13.0 years; range, 30 to 78 years) who were operated and followed in our clinic for AO A2 and A3 distal radius fractures were included in this prospective study. Surface ultrasound (US) imaging was made to the dorsal sides of both wrists of the operated patients at different timepoints postoperatively. The length of screws with radius dorsal cortex penetration and the presence of tendinitis were recorded.
RESULTS
In 15 of 23 patients, the presence of 29 protruding screws was accompanied by tendinitis and, in eight patients, no tendinitis was observed, despite the partial protrusion of screws. A statistically significant correlation was found between the screw protrusion and presence of tendinitis (p<0.05). The number of protruding screws and tendinitis were seen mostly in the second compartment. There was a statistically significant correlation between the protruding screw length of >1.6 mm and the presence tendinitis (p<0.05).
CONCLUSION
Dorsal cortex screw protrusions in the application of volar plate for distal radius fractures can cause tendinitis. Screw protrusions occur more frequently in the second compartment and the development of tendinitis in this compartment is associated with a screw length of >1.6 mm. Screw penetration can be easily identified with intraoperative US to prevent tendinitis and potential tendon ruptures.
Topics: Male; Female; Humans; Adult; Middle Aged; Aged; Radius Fractures; Prospective Studies; Fluoroscopy; Radius; Bone Screws; Wrist Fractures
PubMed: 36700271
DOI: 10.52312/jdrs.2023.856 -
Brain Research Oct 2021The present study aimed to assess spinal tract formation in neurons originating from cervical (C7), brachial (C14), and thoracic (T4) regions, with the lumbar (LS2)...
The present study aimed to assess spinal tract formation in neurons originating from cervical (C7), brachial (C14), and thoracic (T4) regions, with the lumbar (LS2) region as a reference, in a chick embryo. For the assessment of the spinal tracts, we introduced a vector expressing human placental alkaline phosphatase into progenitor cells generated after neural tube closure and belonging to the above segments, using in ovo electroporation. The ascending axons took primarily similar paths: dorsal commissural, ventral commissural, and dorsal non-commissural paths, with some variance depending on their originating segments. Some populations of non-commissural neurons later extended their axons following a ventral path. The elongation rates of these axons are primarily constant and tended to increase over time; however, some variations depending on the originating segments were also observed. Some of the dorsally ascending axons entered into the developing cerebellum, and spinocerebellar neurons originating from T4 projected their axons into the cortex of the cerebellum differently from those from LS2. These results unveil an overall picture of early ascending spinal tract formation.
Topics: Alkaline Phosphatase; Animals; Axons; Brain; Cerebellum; Chick Embryo; Electroporation; GPI-Linked Proteins; Isoenzymes; Neural Pathways; Neural Stem Cells; Neurons; Spinal Cord; Spine
PubMed: 34332964
DOI: 10.1016/j.brainres.2021.147595 -
Human Brain Mapping Jul 2019Interacting with manipulable objects (tools) requires the integration of diverse computations supported by anatomically remote regions. Previous functional neuroimaging...
Interacting with manipulable objects (tools) requires the integration of diverse computations supported by anatomically remote regions. Previous functional neuroimaging research has demonstrated the left supramarginal (SMG) exhibits functional connectivity to both ventral and dorsal pathways, supporting the integration of ventrally-mediated tool properties and conceptual knowledge with dorsally-computed volumetric and structural representations of tools. This architecture affords us the opportunity to test whether interactions between the left SMG, ventral visual pathway, and dorsal visual pathway are differentially modulated when participants plan and generate tool-directed gestures emphasizing functional manipulation (tool use gesturing) or structure-based grasping (tool transport gesturing). We found that functional connectivity between the left SMG, ventral temporal cortex (bilateral fusiform gyri), and dorsal visual pathway (left superior parietal lobule/posterior intraparietal sulcus) was maximal for tool transport planning and gesturing, whereas functional connectivity between the left SMG, left ventral anterior temporal lobe, and left frontal operculum was maximal for tool use planning and gesturing. These results demonstrate that functional connectivity to the left SMG is differentially modulated by tool use and tool transport gesturing, suggesting that distinct tool features computed by the two object processing pathways are integrated in the parietal lobe in the service of tool-directed action.
Topics: Brain Mapping; Female; Gestures; Humans; Magnetic Resonance Imaging; Male; Parietal Lobe; Psychomotor Performance; Tool Use Behavior; Visual Pathways; Young Adult
PubMed: 30900321
DOI: 10.1002/hbm.24565 -
European Journal of Trauma and... May 2024To identify the incidence of dorsal comminution using computed tomography (CT) images and identify predictors of this phenomenon in older adults with low-energy distal...
PURPOSE
To identify the incidence of dorsal comminution using computed tomography (CT) images and identify predictors of this phenomenon in older adults with low-energy distal radius fractures (DRFs).
METHODS
A total of 150 patients aged > 50 years with fall-induced dorsally angulated DRFs were enrolled in this study. Patients were divided into two groups based on the presence of dorsal comminution, defined as a metaphyseal void of greater than one-third of the maximum posterior to anterior depth of the bone on at least three cuts in the sagittal plane on post-reduction CT images. Data on participants' basic demographics, including age, sex, body mass index (BMI), and AO classification of DRFs, were collected. Bone mineral density (BMD) was assessed using T-scores of the femoral neck, and cortical thickness of the distal radius was determined from plain post-reduction radiographs. Radiological parameters and combined ulnar fractures were measured on plain pre-reduction radiographs.
RESULTS
Among study participants, 91 (61%) had dorsal comminution, whereas 59 (39%) had no dorsal comminution on CT images. Both patient groups were compared based on presence of dorsal comminution, and showed no significant differences in age, sex, BMI, BMD, or cortical thickness on radiographs. However, all radiological parameters were better in the no dorsal comminution group than in the dorsal comminution group, and the proportion of patients with combined ulnar fractures was higher in the dorsal comminution group. In the multivariate analysis, the presence of combined ulnar fractures was the only significant predictor of dorsal comminution (p = 0.029, odds ratio = 2.267, 95% confidence interval: 1.085-4.736).
CONCLUSION
The incidence of dorsal comminution is relatively high in patients with low-energy DRFs aged > 50 years. In particular, the presence of combined ulnar fractures is closely associated with dorsal comminution of DRFs. Thus, surgeons should exercise caution when evaluating this phenomenon.
PubMed: 38819680
DOI: 10.1007/s00068-024-02559-y -
Orthopedics Nov 2014There has been a trend away from dorsal fixation of distal radius fractures secondary to a historically higher complication rate. However, the literature on low-profile...
There has been a trend away from dorsal fixation of distal radius fractures secondary to a historically higher complication rate. However, the literature on low-profile dorsal plates and titanium implants for the treatment of these fractures is limited. The goal of the current study was to evaluate hardware-related complications and removal rates after open reduction and internal fixation of unstable, displaced distal radius fractures using a dorsal approach with a low-profile titanium plate. A single surgeon treated 125 patients with isolated, unstable, dorsally displaced distal radius fractures by open reduction and internal fixation using a low-profile titanium dorsal plating system. A total of 110 patients were followed for a minimum of 1 year, and mean follow-up was 27 months (range, 12-74). Outcomes were assessed radiographically and clinically. Satisfactory alignment was achieved in all cases, and no fracture went on to nonunion. Nine patients (8%) required removal of hardware at an average of 12 months (range, 6-34). Six patients (5%) had evidence of extensor tenosynovitis intraoperatively, but no extensor tendon ruptures were identified. Overall, using the Gartland and Werley score, results were excellent in 82 patients, good in 22 patients, fair in 5 patients, and poor in 1 patient. Six complications accounted for the fair and poor results. The average Disabilities of the Arm, Shoulder and Hand (DASH) score at latest follow-up was 6 (range, 0-25). This series showed that the technique of dorsal plating with a low-profile titanium plate is safe and effective.
Topics: Adolescent; Adult; Aged, 80 and over; Bone Plates; Female; Fracture Fixation, Internal; Humans; Male; Middle Aged; Postoperative Complications; Radiography; Radius Fractures; Range of Motion, Articular; Treatment Outcome
PubMed: 25361374
DOI: 10.3928/01477447-20141023-54 -
Frontiers in Veterinary Science 2020Laminitis is a debilitating disorder resulting in irreversible anatomical changes in the feet of equids. Assessing specific anatomical features through radiography and...
Laminitis is a debilitating disorder resulting in irreversible anatomical changes in the feet of equids. Assessing specific anatomical features through radiography and venography provides diagnostic and prognostic information. The reference ranges are well-established in horses, but not in donkeys. It is also uncertain as to whether these ranges can be applied to every donkey breed. The present study characterizes the radiological and venographic hoof anatomy of healthy feet of Amiata donkeys and defines the changes associated with severe and mild laminitis. A total of 16 forefeet were evaluated in 8 Amiata jennies. The animals underwent musculoskeletal examination, Obel grading assessment and radiological evaluation. Based on clinical examination and radiographic findings, the forefeet were grouped as healthy, mild or severe laminitic feet, thus the digital venograms were performed according to the group definition. Radiology revealed 7/16 healthy, 4/16 mild laminitic, and 5/16 severe laminitic forefeet. Statistical analysis showed differences between the healthy and laminitic forefeet for the dorsal angle ( < 0.0001) and angle of solar aspect ( < 0.0001) of the distal phalanx, for deviation between dorsal aspect of distal phalanx and the hoof wall ( < 0.0001) and phalangeal rotation angle ( = 0.0032). Venography was abnormal in mild and severe laminitic forefeet. In particular, the vascularization was reduced or absent at the lamellar-circumflex junction dorsally, at the sub-lamellar vascular bed and at the circumflex veins. Coronary plexus vascularization was absent in severe laminitic forefeet. This study provides the radiological parameters for the assessment of healthy and laminitic forefeet of Amiata donkeys. The mild laminitic foot venogram showed decreased vascularization mainly on lamellar-circumflex junction and sub-lamellar vascular bed, in latero-medial views. The severe laminitic foot showed very poor or absent vascularization in multiple areas. The technique is easily applicable and provides diagnostic support in laminitis.
PubMed: 33409297
DOI: 10.3389/fvets.2020.601665