ObjectiveTo compare magnetic resonance images (MRIs) of the sacroiliac (SI) joints of healthy subjects and individuals with known mechanical strain acting upon the SI joints to those of patients with axial spondyloarthritis (SpA) and patients with chronic back pain.MethodsThree readers who had received standardized training and were blinded with regard to study group randomly scored MRIs of the SI joints of 172 subjects, including 47 healthy individuals without current or past back pain, 47 axial SpA patients from the Spondyloarthritis Caught Early (SPACE) cohort (with a previous MRI confirmed positive for sacroiliitis), 47 controls with chronic back pain (irrespective of MRI results) from the SPACE cohort, 7 women with postpartum back pain, and 24 frequent runners. MRIs were scored according to the Assessment of SpondyloArthritis international Society (ASAS) definition and Spondyloarthritis Research Consortium of Canada (SPARCC) index.ResultsOf the 47 healthy volunteers, 11 (23.4%) had an MRI positive for sacroiliitis, compared to 43 (91.5%) of 47 axial SpA patients and 3 (6.4%) of 47 patients with chronic back pain. Three (12.5%) of the 24 runners and 4 (57.1%) of the 7 women with postpartum back pain had a positive MRI. Using a SPARCC cutoff of ≥2 for positivity, 12 (25.5%) of 47 healthy volunteers, 46 (97.9%) of 47 positive axial SpA patients, 5 (10.6%) of 47 controls with chronic back pain, 4 (16.7%) of 24 runners, and 4 (57.1%) of 7 women with postpartum back pain had positive MRIs. Deep bone marrow edema (BME) lesions were not found in healthy volunteers, patients with chronic back pain, or runners, but were found in 42 (89.4%) of 47 positive axial SpA patients and in 1 (14.3%) of 7 women with postpartum back pain.ConclusionA substantial proportion of healthy individuals without current or past back pain has an MRI positive for sacroiliitis according to the ASAS definition. Deep (extensive) BME lesions are almost exclusively found in axial SpA patients.
ldCT, covering the whole spine, detects more progression in the form of new and growing syndesmophytes in patients with AS compared with CR, which is limited to the cervical and lumbar spine. Most progression occurred in the thoracic spine.
So, although the pathophysiology of axSpA remains incompletely understood, the progress in recent years in several fields of research in axSpA including genetics, diagnosis, imaging and therapeutics, hold great promise for the future.
ronectin on stromal cells. 11
Lipophilic compounds that do not affect GJIC had no effect onWe asked if the gap junctions which are present in haemo-
drugs (Ref. 13 and Krenács and Rosendaal, in preparation).Keywords: blood formation; haemopoietic regulation; gap junctions; Cx43; Amphotericin B; stem cells; stroma Gap junctions are intramembranous channels through the walls of adjacent cells which permit the passage of watersoluble molecules smaller than 1 kDa, which could be messengers. Channels are gated, open when cytosolic [Ca 2+ i ] is Introduction high or pH low and closed when the opposite conditions occur. A single gap junction channel is called a connexon Normally blood cells form only in those parts of the body, and is formed by two hemi-connexons, one in each cell wall. especially bone marrow, where specialised cells calledThe channels group into plaques and these are the functional haemopoietic stromal cells are found. Grafting these cells into gap junctions. Each hemi-connexon is formed by six identical, non-medullary tissues such as the kidney enables such tissues membrane-spanning proteins called connexins. Thirteen conto form blood. 1 We have been able to understand many nexin species have been described and named for their molaspects of lifelong blood formation supported by stromal cells ecular weights in thousands, abbreviated as Cx43, etc. 15 Cerusing long-term bone marrow cultures. 2 tain kinds of stromal cell in haemopoietic tissue are coupled It was thought that long-term cultures required an underlyby Cx43 gap junctions, but we do not know yet if that is the ing monolayer of adherent bone marrow stromal cells to form only connexin species that can form haemopoietic junctions. blood cells for a long time. Bentley 3 indicated that stroma and There are functional gap junctions in long-term cultures stem cells need only be close for the maintenance of spleen between stromal and haemopoietic cells. 12 To investigate a colony-forming units and Brandt and colleagues 4 found that possible role of gap junctions in the regulation of haemopothe underlay could be replaced by adding recombinant iesis we studied the numerical alterations in clone formation interleukins IL-1 alpha, IL-3, IL-6, or granulocyte-macrophage and progenitor cell generation in stroma-supported long-term colony-stimulating factor (GM-CSF) at 2-day intervals. IL-3 cultures 2,[16][17][18] in the presence of lipophilic substances which block GJIC. Absolute numbers of haemopoietic clones were estimated using the cobblestone area forming cell (CAFC) culture carried out in a limited dilution set-up. In the mouse
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