Congenital generalised bone dysplasias: a clinical, radiological, and epidemiological survey.

The point prevalence at birth of generalised bone dysplasias was estimated by a study of all children born between 1 January 1970 and 31 December 1983 in the county of Fyn (Denmark). Additionally the population prevalence on 31 December 1983 of all patients with generalised bone dysplasias in this county was determined. The county is a well defined, representative subregion of Denmark which demographically comprises a cross section of about 9% of the Danish population. In total, bone dysplasias were found to be more frequent than generally assumed. Achondroplasia was, however, less common with a point prevalence at birth of 1.3 per 100,000, while osteogenesis imperfecta (21.8), multiple epiphyseal dysplasia tarda (9.0), achondrogenesis (6.4), osteopetrosis (5.1), and thanatophoric dysplasia (3.8) were found more frequently. It is striking how many bone dysplasias are still erroneously classified as achondroplasia. Correct diagnosis is important for a valid prognosis, for treatment, and for genetic counselling. The diagnosis relies almost exclusively on the radiographical findings.     

Spontaneous generation of functional osteoclasts from synovial fluid mononuclear cells as a model of inflammatory osteoclastogenesis

In osteoimmunology, osteoclastogenesis is understood in the context of the immune system. Today, the in vitro model for osteoclastogenesis necessitates the addition of recombinant human receptor activator of nuclear factor kappa‐B ligand (RANKL) and macrophage colony‐stimulating factor (M‐CSF). The peripheral joints of patients with rheumatoid arthritis (RA) and spondyloarthritis (SpA) are characterized by an immune‐mediated inflammation that can lead to bone destruction. Here, we evaluate spontaneous in vitro osteoclastogenesis in cultures of synovial fluid mononuclear cells (SFMCs) activated only in vivo. SFMCs were isolated and cultured for 21 days at 0.5–1.0 × 10⁶ cells/mL in culture medium. SFMCs and healthy control peripheral blood monocytes were cultured with RANKL and M‐CSF as controls. Tartrate‐resistant acid phosphatase (TRAP) positive multinucleated cells were found in the SFMC cultures after 21 days. These cells expressed the osteoclast genes calcitonin receptor, cathepsin K, and integrin β3, formed lacunae on dentin plates and secreted matrix metalloproteinase 9 (MMP9) and TRAP. Adding RANKL and M‐CSF potentiated this secretion. In conclusion, we show that SFMCs from inflamed peripheral joints can spontaneously develop into functionally active osteoclasts ex vivo. Our study provides a simple in vitro model for studying inflammatory osteoclastogenesis.     

Associations between recreational exercise and chronic pain in the general population: evidence from the HUNT 3 study

The evidence for an association between leisure-time physical activity and prevalence of pain is insufficient. This study investigated associations between frequency, duration, and intensity of recreational exercise and chronic pain in a cross-sectional survey of the adult population of a Norwegian county (the Nord-Trøndelag Health Study; HUNT 3). Of the 94,194 invited to participate, complete data were obtained from 46,533 participants. Separate analyses were performed for the working-age population (20-64 years) and the older population (65 years or more). When defined as pain lasting longer than 6 months, and of at least moderate intensity during the past month, the overall prevalence of chronic pain was 29%. We found that increased frequency, duration, and intensity of exercise were associated with less chronic pain in analyses adjusted for age, education, and smoking. For those aged 20-64 years, the prevalence of chronic pain was 10-12% lower for those exercising 1-3 times a week for at least 30 minutes duration or of moderate intensity, relative to those not exercising. Dependent on the load of exercise, the prevalence of chronic pain was 21-38% lower among older women who exercised, relative to those not exercising. Similar, but somewhat weaker, associations were seen for older men. This study shows consistent and linear associations between frequency, duration, and intensity of recreational exercise and chronic pain for the older population, and associations without an apparent linear shape for the working-age population.     

On Pattern Selection in Three-Dimensional Bénard-Marangoni Flows

In this paper we study Bénard-Marangoni convection in confined containers where a thin fluid layer is heated from below. We consider containers with circular, square and hexagonal cross-sections. For Marangoni numbers close to the critical Marangoni number, the flow patterns are dominated by the appearance of the wellknown hexagonal convection cells. The main purpose of this computational study is to explore the possible patterns the system may end up in for a given set of parameters. In a series of numerical experiments, the coupled fluid-thermal system is started with a zero initial condition for the velocity and a random initial condition for the temperature. For a given set of parameters we demonstrate that the system can end up in more than one state. For example, the final state of the system may be dominated by a steady convection pattern with a fixed number of cells, however, the same system may occasionally end up in a steady pattern involving a slightly different number of cells, or it may end up in a state where most of the cells are stationary, while one or more cells end up in an oscillatory state. For larger aspect ratio containers, we are also able to reproduce dislocations in the convection pattern, which have also been observed experimentally. It has been conjectured that such imperfections (e.g., a localized star-like pattern) are due to small irregularities in the experimental setup (e.g., the geometry of the container). However, we show, through controlled numerical experiments, that such phenomena may appear under otherwise ideal conditions. By repeating the numerical experiments for the same non-dimensional numbers, using a different random initial condition for the temperature in each case, we are able to get an indication of how rare such events are. Next, we study the effect of symmetrizing the initial conditions. Finally, we study the effect of selected geometry deformations on the resulting convection patterns.