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At least 613 records · Page 34Linked to original sources
PubMed1996

A novel mesoderm inducer, Madr2, functions in the activin signal transduction pathway.

A functional assay to clone mouse mesoderm inducers has identified the mouse gene Mad related 2 (Madr2). Madr2 induces dorsal mesoderm from Xenopus ectoderm and can mimic the organizer in recruiting neighboring cells into a second axis. By analyzing the expression of a lacZ/Madr2 fusion protein, we find Madr2 confined to the nucleus in the deep, anterior cells of the second axis, whereas in epidermal and more posterior cells the protein is cytoplasmically localized. This context-dependent nuclear localization suggests that in certain regions of the embryo, Madr2 responds to a localized signal and amplifies this signal to form the second axis. Furthermore, although Madr2 remains unlocalized in ectodermal explants, addition of activin enhances the concentration of Madr2 in the nucleus. Significantly, a functional lacZ fusion to a carboxy-terminal portion of Madr2 is nuclear localized even in the absence of activin. This indicates that Madr2 contains a domain that can activate downstream components and a repressive domain that anchors the protein in the cytoplasm. Nuclear localization of Madr2 in response to activin, and the activin-like phenotypes induced by overexpression of Madr2, indicate that Madr2 is a signal transduction component that mediates the activity of activin.

Activins↗
PubMed1999

Conserved requirement for EGF-CFC genes in vertebrate left-right axis formation.

Specification of the left-right (L-R) axis in the vertebrate embryo requires transfer of positional information from the node to the periphery, resulting in asymmetric gene expression in the lateral plate mesoderm. We show that this activation of L-R lateral asymmetry requires the evolutionarily conserved activity of members of the EGF-CFC family of extracellular factors. Targeted disruption of murine Cryptic results in L-R laterality defects including randomization of abdominal situs, hyposplenia, and pulmonary right isomerism, as well as randomized embryo turning and cardiac looping. Similarly, zebrafish one-eyed pinhead (oep) mutants that have been rescued partially by mRNA injection display heterotaxia, including randomization of heart looping and pancreas location. In both Cryptic and oep mutant embryos, L-R asymmetric expression of Nodal/cyclops, Lefty2/antivin, and Pitx2 does not occur in the lateral plate mesoderm, while in Cryptic mutants Lefty1 expression is absent from the prospective floor plate. Notably, L-R asymmetric expression of Nodal at the lateral edges of the node is still observed in Cryptic mutants, indicating that L-R specification has occurred in the node but not the lateral plate. Combined with the previous finding that oep is required for nodal signaling in zebrafish, we propose that a signaling pathway mediated by Nodal and EGF-CFC activities is essential for transfer of L-R positional information from the node.

Animals↗
PubMed1975

Sudden death in rheumatoid arthritis with atlanto-axial dislocation.

A post mortem material of 11 consecutive cases of severe atlanto-axial dislocation (a.a.d.) with cord compression is reported. The total number of deaths from rheumatoid arthritis (RA) during the period of 5 years was 104, and all were autopsied. Neurological symptoms correlated poorly to fatal a.a.d. Hemiplegia was found in three cases, one of which, however, was caused by thrombosis cerebri. Spastic signs were transiently recorded in two patients and dysphagia in a further two. Five patients had a history of recent vomiting. A.a.d. was the sole or main cause of death in 8 cases and contributory in 2. Sudden death occurred in 7 of the cases. Only 2 cases had obtained a correct diagnosis intra vitam. The CNS findings at autopsy consisted of cord compression (11/11 cases), cord malacia (2/11) and cerebral oedema (3/11). One case had polyarteritis and renal amyloidosis and one pulmonary carcinoma with metastatic spread. Signs of active inflammation in the axial joints were present in 4 cases. This study, based on systematic post mortem examinations, revealed an unexpectedly high and not previously reported incidence of fatal medulla compression in RA patients with a.a.d. (10%).

Arthritis, Rheumatoid↗
PubMed1988

Clinical findings in 12 patients with MPS IV A (Morquio's disease). Further evidence for heterogeneity. Part III: Odontoid dysplasia.

Odontoid dysplasia in the absence or presence of atlanto-axial instability was found in all cases. In general, this correlated well with the overall clinical severity of the condition and illustrates the importance of careful follow-up of these patients. Symptoms or signs of cervical cord compression merit further investigation. Proven compromise of the upper cervical cord is an indication for posterior fusion of the upper cervical spine.

Atlanto-Axial Joint↗
PubMed1976

Fracture of the odontoid process.

A review of 26 cases of odontoid fractures has been carried out. Late diagnosis and consequent delay in treatment were found to be important causes of non-union. Myelopathy in odontoid fractures is of two types. One type is that present immediately after injury, while the other is delayed. In treatment of long-standing cases, only fusion without posterior decompression should be done. If the latter procedure is carried out, it can produce medullospinal haematomyelia with respiratory arrest and tetraplegia. In the performance of atlanto-axial fusion, the technique of bone grafting and the use of thick wires need emphasis.

Adolescent↗
PubMed1978

Some specific anatomical features of the atlas and axis: dens, epitransverse process and articular facets.

Metrical and morphological findings, based on 107 human vertebral columns, related to the variations of the dens are given, and differences in the depth of the superior articular facets of the atlas and specific pertinent details related to the os odontoideum and epitransverse process are also provided and their possible clinical relevance indicated. Findings reveal considerable variation in the height of the dens (11 to 18 mm), but remarkably little in its anteroposterior and transverse diameters at the root. The use of the term "hypoplasia" with reference to the dens is discussed, and a need for more rigid criterian in the use of this term stressed. It is also suggested that there may be sufficient radiological evidence in a lateral radiography to lead one to suspect the presence of an os odontoideum or a separate dens caused by trauma in the distant past.

Adult↗
PubMed1984

Odontoid fractures, systemic disease and conservative care.

Patients admitted to the Prince Henry Hospital Spinal Unit between January 1982 and January 1983 with a diagnosis of fracture of the odontoid process of the axis were reviewed. There were nine patients representing 20% of all new cervical fractures. The mean age was 64.5 +/- 19.3 years. Alcoholism, brain damage following head injury, osteo-arthritis, cervical spondylosis, rheumatoid arthritis and osteoporosis may be complicating factors in the management of odontoid fractures. A fracture of the odontoid in an elderly patient with a history of minimal trauma suggests osteoporosis. Early mobilization in a custom-moulded orthosis with frequent radiological monitoring prevents the complications of prolonged bed rest.

Aged↗
PubMed2006

Functional connectivity between trigeminal and occipital nerves revealed by occipital nerve blockade and nociceptive blink reflexes.

Headache syndromes often suggest occipital and neck involvement, although it is still unknown to what extent branches of segment C1-C3 contribute actively to primary headache. Pain within the occipital area may be referred to the trigeminal territory. However, a modulation of trigeminal transmission by affecting cervical input in humans has not been elucidated so far. A convergence of cervical and trigeminal input at the level of the caudal part of the trigeminal nucleus in the brainstem has been suggested due to anatomical and neurophysiological studies in animals. We examined the R2 components of the nociceptive blink reflex responses in 15 healthy subjects before and after unilateral nerve blockade of the greater occipital nerve with 5 ml prilocain (1%). R2 response areas (AUC) decreased and the R2 latencies increased significantly after the nerve blockade only on the side of injection. AUC and latencies on the non-injection side remained stable. Thresholds for sensory or pain perception did not differ significantly between the repeated measurements on both sides. Our findings extend previous results related to anatomical and functional convergence of trigeminal and cervical afferent pathways in animals and suggest that the modulation of this pathway is of potential benefit in primary headache disorders.

Adult↗