-
The Journal of Neuroscience : the... May 2011In the developing spinal cord, most oligodendrocyte precursors (OLPs) arise from the ventral ventricular zone (VZ) under the influence of Sonic Hedgehog, but a minority...
In the developing spinal cord, most oligodendrocyte precursors (OLPs) arise from the ventral ventricular zone (VZ) under the influence of Sonic Hedgehog, but a minority are generated from the dorsal VZ in a Hedgehog-independent manner. In the developing forebrain too, OLPs arise from both the ventral and the dorsal VZ. It is not known whether dorsally and ventrally derived oligodendrocyte (OL) lineage cells have different properties. We generated a dual reporter mouse line to color code ventrally and dorsally derived OLPs (vOLPs and dOLPs) and their differentiated oligodendrocyte progeny (vOLs and dOLs) for functional studies. We found that ∼80% of OL lineage cells in the postnatal spinal cord and ∼20% in the corpus callosum are ventrally derived. In both spinal cord and corpus callosum, vOLPs and dOLPs had indistinguishable electrical properties, as did vOLs and dOLs. However, vOLPs and dOLPs had different migration and settling patterns. In the spinal cord, vOLPs appeared early and spread uniformly throughout the cord, whereas dOLPs arrived later and remained mainly in the dorsal and dorsolateral funiculi. During adulthood, corticospinal and rubrospinal tracts became myelinated mainly by dOLs, even though vOLs dominated these tracts during early postnatal life. Thus, dOLPs are electrically similar to vOLPs but appear to outcompete them for dorsal axons.
Topics: Animals; Cell Lineage; Corpus Callosum; Electrophysiology; Immunohistochemistry; Mice; Mice, Transgenic; Myelin Sheath; Oligodendroglia; Spinal Cord
PubMed: 21543611
DOI: 10.1523/JNEUROSCI.6474-10.2011 -
The Journal of Hand Surgery Mar 2012Volar plating for distal radius fractures has caused extensor tendon ruptures resulting from dorsal screw prominence. This study was designed to determine the...
PURPOSE
Volar plating for distal radius fractures has caused extensor tendon ruptures resulting from dorsal screw prominence. This study was designed to determine the biomechanical impact of placing unicortical distal locking screws and pegs in an extra-articular fracture model.
METHODS
We applied volar-locking distal radius plates to 30 osteoporotic distal radius models. We divided radiuses into 5 groups based on distal locking fixation: bicortical locked screws, 3 lengths of unicortical locked screws (abutting the dorsal cortex [full length], 75% length, and 50% length to dorsal cortex), and unicortical locked pegs. Distal radius osteotomy simulated a dorsally comminuted, extra-articular fracture. We determined each construct's stiffness under physiologic loads (axial compression, dorsal bending, and volar bending) before and after 1,000 cycles of axial conditioning and before axial loading to failure (2 mm of displacement) and subsequent catastrophic failure.
RESULTS
Cyclic conditioning did not alter the constructs' stiffness. Stiffness to volar bending and dorsal bending forces were similar between groups. Final stiffness under axial load was statistically equivalent for all groups: bicortical screws (230 N/mm), full-length unicortical screws (227 N/mm), 75% length unicortical screws (226 N/mm), 50% length unicortical screws (187 N/mm), and unicortical pegs (226 N/mm). Force at 2-mm displacement was significantly less for 50% length unicortical screws (311 N) compared with bicortical screws (460 N), full-length unicortical screws (464 N), 75% length unicortical screws (400 N), and unicortical pegs (356 N). Force to catastrophic fracture was statistically equivalent between groups, but mean values for pegs (749 N) and 50% length unicortical (702 N) screws were 16% to 21% less than means for bicortical (892 N), full-length unicortical (860 N), and 75% length (894 N) unicortical constructs.
CONCLUSIONS
Locked unicortical distal screws of at least 75% length produce construct stiffness similar to bicortical fixation. Unicortical distal fixation for extra-articular distal radius fractures should be entertained to avoid extensor tendon injury because this technique does not appear to compromise initial fixation.
CLINICAL RELEVANCE
Using unicortical fixation during volar distal radius plating may protect extensor tendons without compromising fixation.
Topics: Biomechanical Phenomena; Bone Plates; Bone Screws; Fracture Fixation, Internal; Humans; Models, Anatomic; Osteoporotic Fractures; Radius Fractures; Tendon Injuries
PubMed: 22305729
DOI: 10.1016/j.jhsa.2011.12.013 -
Acta Orthopaedica Apr 2021Background and purpose - It is unclear what degree of malalignment of a fracture of the distal radius benefits from reduction. This study addressed the following...
Background and purpose - It is unclear what degree of malalignment of a fracture of the distal radius benefits from reduction. This study addressed the following questions: (1) What is the interobserver reliability of surgeons concerning the recommendation for a reduction for dorsally displaced distal radius fractures? (2) Do expert-based criteria for reduction improve reliability or not?Methods - We sent out 2 surveys to a group of international hand and fracture surgeons. On the first survey, 80 surgeons viewed radiographs of 95 dorsally displaced (0° to 25°) fractures of the distal radius. The second survey randomized 68 participants to either receive or not receive expert-based criteria for when to reduce a fracture and then viewed 20 radiographs of fractures with dorsal angulation between 5° and 15°. All participants needed to indicate whether they would advise a reduction or not.Results - In the 1st study, the interrater reliability of advising a reduction was fair (kappa 0.31). Multivariable linear regression analyses indicated that each additional degree of dorsal angulation increased the chance of recommending a reduction by 3%. In the 2nd study, reading criteria for reduction did not increase interobserver reliability for recommending a reduction.Interpretation - There is notable variation in recommendations for reduction that is not accounted for by surgeon or patient factors and is not diminished by exposure to expert criteria. Surgeons should be aware of their biases and develop strategies to inform patients and share the decision regarding whether to reduce a fracture of the distal radius.
Topics: Aged; Female; Fracture Fixation; Humans; Male; Middle Aged; Observer Variation; Radiography; Radius Fractures; Reproducibility of Results; Surveys and Questionnaires
PubMed: 33183107
DOI: 10.1080/17453674.2020.1846853 -
Neuron Aug 2015Persistent mechanical hypersensitivity that occurs in the setting of injury or disease remains a major clinical problem largely because the underlying neural circuitry...
Persistent mechanical hypersensitivity that occurs in the setting of injury or disease remains a major clinical problem largely because the underlying neural circuitry is still not known. Here we report the functional identification of key components of the elusive dorsal horn circuit for mechanical allodynia. We show that the transient expression of VGLUT3 by a discrete population of neurons in the deep dorsal horn is required for mechanical pain and that activation of the cells in the adult conveys mechanical hypersensitivity. The cells, which receive direct low threshold input, point to a novel location for circuit initiation. Subsequent analysis of c-Fos reveals the circuit extends dorsally to nociceptive lamina I projection neurons, and includes lamina II calretinin neurons, which we show also convey mechanical allodynia. Lastly, using inflammatory and neuropathic pain models, we show that multiple microcircuits in the dorsal horn encode this form of pain.
Topics: Amino Acid Transport Systems, Acidic; Animals; Hyperalgesia; Mice; Mice, Knockout; Nerve Net; Organ Culture Techniques; Pain; Spinal Cord Dorsal Horn; Touch
PubMed: 26291162
DOI: 10.1016/j.neuron.2015.07.029 -
Arab Journal of Urology Jun 2018To report the surgical details and results of our technique of buccal mucosal graft (BMG) urethroplasty for panurethral stricture, as many studies have reported repair...
OBJECTIVE
To report the surgical details and results of our technique of buccal mucosal graft (BMG) urethroplasty for panurethral stricture, as many studies have reported repair of panurethral stricture by single-stage BMG urethroplasty by placing buccal mucosa ventrally, dorsally or dorsolaterally.
PATIENTS AND METHODS
This was an observational analysis of 38 patients with panurethral stricture treated by placing two BMGs, one as a ventral onlay in the proximal bulbar urethra and the other as a dorsal onlay in the distal bulbar and penile urethra. Success was defined as asymptomatic state with or without need for a postoperative single intervention such as dilatation or internal urethrotomy.
RESULTS
The 38 patients had a mean age of 44 years, with lichen sclerosus as the predominant cause of stricture. The ultimate success rate was 84.2% at the end of 3 months and 89.5% at the end of 1 year. Recurrent strictures appeared only in the failed cases during the follow-up period of 11 months. None of the patients needed redo urethroplasty during the follow-up period.
CONCLUSIONS
A proximal ventral and distal dorsal onlay technique of BMG urethroplasty is an available alternative for repairing panurethral stricture. The technique described is simple and easily reproducible with encouraging results compared to other similar techniques.
PubMed: 29892484
DOI: 10.1016/j.aju.2017.11.007 -
Molecular Imaging and Biology Oct 2021Many preclinical cancer studies use mice with varied phenotypes to monitor tumor treatment. We compared survival and optical imaging characteristics of strains with...
BACKGROUND
Many preclinical cancer studies use mice with varied phenotypes to monitor tumor treatment. We compared survival and optical imaging characteristics of strains with varied coat colors harboring luciferase-expressing disseminated lymphoma.
RESULTS
Luciferase-expressing lymphoma cells (Raji-luc) were injected via tail vein into severe combined immunodeficient (SCID) and Rag2-IL2rg (R2G2) mice, and survival was tracked. Tumor signals were obtained by imaging ventral and dorsal aspects of mice. Signal attenuation by isolated mouse pelts was measured in vitro. R2G2 mice had decreased survival compared to SCID mice (17 vs. 32 days, p<0.001) despite similar bioluminescence signal when mice were imaged dorsally (p=0.37). However, signal was 17.3-fold higher in R2G2 mice compared to SCID (p<0.001) when imaged ventrally. Isolated dark R2G2 dorsal pelts attenuated signal more than ventral pelts when placed over cells in vitro.
CONCLUSIONS
Mouse pelt color and imaging aspect are critical considerations for quantifying bioluminescent tumor signal, and the R2G2 mouse strain may prove useful for preclinical targeted therapy studies.
Topics: Animals; Cell Line; Disease Models, Animal; Female; Hair; Luminescent Measurements; Lymphoma; Mice; Mice, SCID; Mice, Transgenic; Radiotherapy; Skin Pigmentation
PubMed: 33830414
DOI: 10.1007/s11307-021-01594-0 -
Developmental Biology Sep 2013Fibroblast growth factor (FGF) signalling plays a key role in early embryonic development and cell migration in vertebrates and in invertebrates. To gain novel insights...
Fibroblast growth factor (FGF) signalling plays a key role in early embryonic development and cell migration in vertebrates and in invertebrates. To gain novel insights into FGF signalling in an arthropod, we characterized the fgf1b ortholog in the beetle Tribolium that is not represented in the Drosophila genome. We found that FGF1b dependent signalling organizes the anterior to posterior axis of the early embryo. The loss of Tc-fgf1b function in Tribolium by RNA interference resulted in the reduction of the anteriormost extraembryonic fate, in an anterior shift of embryonic fate and in the loss or malformation of anterior embryonic structures. Without intact extraembryonic membranes the serosa and the amnion, Tc-fgf1b(RNAi) embryos did not undergo morphogenetic movements and remained posteriorly localized throughout embryogenesis. Only weakly affected embryos developed into a cuticle that show dorsally curved bodies with head defects and a dorsal opening. Except for the posterior dorsal amnion, the overall topology of the dorsal-ventral axis seemed unaffected. Moreover, FGF signalling was not required for the onset of mesoderm formation but for fine-tuning this tissue during later development. We also show that in affected embryos the dorsal epidermis was expanded and expressed Tc-dpp at a higher level. We conclude that in the Tribolium blastoderm embryo, FGF1-signalling organizes patterning along the AP-axis and also balances the expression level of Dpp in the dorsal epidermis, a tissue critically involved in dorsal closure.
Topics: Animals; Body Patterning; Cell Lineage; Cell Membrane; Cloning, Molecular; Fibroblast Growth Factor 1; Gene Expression Profiling; Gene Expression Regulation, Developmental; Phenotype; RNA Interference; Signal Transduction; Transforming Growth Factor beta; Tribolium
PubMed: 23769707
DOI: 10.1016/j.ydbio.2013.05.031 -
Scientific Reports Apr 2020Sauropods were among the most diverse lineages of dinosaurs, with an ample geographic distribution throughout the Mesozoic. This evolutionary success is largely...
Sauropods were among the most diverse lineages of dinosaurs, with an ample geographic distribution throughout the Mesozoic. This evolutionary success is largely attributed to neck elongation and its impact on feeding efficiency. However, how neck elongation influenced exactly on feeding strategies is subject of debate. The process of mounting a nearly complete virtual skeleton of Spinophorosaurus nigerensis, from the Middle (?) Jurassic of Niger, has revealed several previously unknown osteological adaptations in this taxon. Wedged sacral and posterior dorsal vertebrae cause the presacral column to deflect antero-dorsally. This, together with elongated scapulae and humeri make the anterior region of the skeleton vertically lengthened. Also, elongated prezygapophyseal facets on the cervical vertebrae and a specialized first dorsal vertebra greatly increase the vertical range of motion of the neck. These characters support this early eusauropod as a more capable high browser than more basally branching sauropods. While limb proportions and zygapophyseal facets vary among Eusauropoda, the sacrum retained more than 10° of wedging in all Eusauropoda. This implied a functional constraint for sauropod species which evolved lower browsing feeding strategies: the antero-dorsal sloping caused by the sacrum had to be counteracted with further skeletal modifications, e.g. a ventrally curved mid to anterior presacral spine to hinder the dorsal slope of the whole presacral series caused by the wedged sacrum. This suggests that at least the last common ancestor of Eusauropoda developed high browsing capabilities, partially due to the modified wedged sacrum, likely a potential synapomorphy of the clade and key in the evolutionary history of the group.
Topics: Adaptation, Physiological; Animals; Biological Evolution; Cervical Vertebrae; Dinosaurs; Feeding Behavior; Fossils; History, Ancient; Musculoskeletal System; Neck; Niger; Phylogeny; Range of Motion, Articular; Sacrum
PubMed: 32313018
DOI: 10.1038/s41598-020-63439-0 -
Plastic and Reconstructive Surgery.... Jul 2022Carpal coalition is a rare congenital presentation of 2 or more fused carpal bones due to a failure of apoptotic segmentation during development. The most common subtype...
Carpal coalition is a rare congenital presentation of 2 or more fused carpal bones due to a failure of apoptotic segmentation during development. The most common subtype is lunotriquetral coalition (LTC). Most cases are asymptomatic and found incidentally on imaging; however, a few symptomatic cases requiring treatment have been reported. Surgical intervention of arthrodesis and proximal row carpectomy in adults have been reported where conservative management of splinting, physiotherapy, anti-inflammatory medication, or steroid injections have failed. We report a unique case of Minnaar type 2 LTC in a 20-year-old man with a 6-year history of daily right wrist pain and symptomatic wrist instability whose previous conservative therapies failed. Midcarpal instability and volar intercalated segment instability-volar flexion of the lunate-were present. A novel technique using the palmaris longus tendon to reconstruct the triquetrohamate, triquetrocapitate, and dorsal radiolunate ligaments was performed. The graft was secured dorsally to the hamate, triquetrum, and capitate. An additional graft from the lunate to distal radius acted as a biomechanical checkrein. There were no complications. Temporary Kirschner wires were removed 2 months postoperatively, followed by occupational hand therapy. At 1-year follow-up, the patient no longer reported pain or lunotriquetral tenderness. Midcarpal instability and volar intercalated segment instability resolved. Postoperative right wrist flexion and extension were 40 and 75 degrees, respectively. We discuss the successful outcome of this novel technique as an alternative to arthrodesis in the surgical management of LTC.
PubMed: 35813107
DOI: 10.1097/GOX.0000000000004430 -
PloS One 2013The motor cortex represents muscle and joint control and projects to spinal cord interneurons and-in many primates, including humans-motoneurons, via the corticospinal...
The motor cortex represents muscle and joint control and projects to spinal cord interneurons and-in many primates, including humans-motoneurons, via the corticospinal tract (CST). To examine these spinal CST anatomical mechanisms, we determined if motor cortex sites controlling individual forelimb joints project differentially to distinct cervical spinal cord territories, defined regionally and by the locations of putative last-order interneurons that were transneuronally labeled by intramuscular injection of pseudorabies virus. Motor cortex joint-specific sites were identified using intracortical-microstimulation. CST segmental termination fields from joint-specific sites, determined using anterograde tracers, comprised a high density core of terminations that was consistent between animals and a surrounding lower density projection that was more variable. Core terminations from shoulder, elbow, and wrist control sites overlapped in the medial dorsal horn and intermediate zone at C5/C6 but were separated at C7/C8. Shoulder sites preferentially terminated dorsally, in the dorsal horn; wrist/digit sites, more ventrally in the intermediate zone; and elbow sites, medially in the dorsal horn and intermediate zone. Pseudorabies virus injected in shoulder, elbow, or wrist muscles labeled overlapping populations of predominantly muscle-specific putative premotor interneurons, at a survival time for disynaptic transfer from muscle. At C5/C6, CST core projections from all joint zones were located medial to regions of densely labeled last-order interneurons, irrespective of injected muscle. At C7/C8 wrist CST core projections overlapped the densest interneuron territory, which was located in the lateral intermediate zone. In contrast, elbow CST core projections were located medial to the densest interneuron territories, and shoulder CST core projections were located dorsally and only partially overlapped the densest interneuron territory. Our findings show a surprising fractionation of CST terminations in the caudal cervical enlargement that may be organized to engage different spinal premotor circuits for distal and proximal joint control.
Topics: Afferent Pathways; Animals; Cervical Vertebrae; Cholera Toxin; Female; Forelimb; Ganglia; Interneurons; Joints; Male; Mice; Mice, Inbred C57BL; Motor Cortex; Muscles; Organ Specificity; Pyramidal Tracts; Staining and Labeling
PubMed: 24058570
DOI: 10.1371/journal.pone.0074454