Radiographic parameters for diagnosing sand colic in horses

<p>Abstract</p> <p>Background</p> <p>Ingestion of sand can cause colic, diarrhoea and weight loss in horses, but these signs are unspecific and can have many other causes. The amount of sand that induces disease may vary between individuals. To avoid over-diagnosing, it is important to determine the amount of sand that can be found in horses without clinical signs of gastrointestinal disease. The aim of this study was to use previously suggested parameters for establishing a radiographic diagnosis of sand colic, and compare these findings between a sand colic group and a control group.</p> <p>Methods</p> <p>Abdominal radiographs were obtained in 30 horses with a complaint unrelated to the gastrointestinal tract. In addition, archived abdominal radiographs of 37 clinical cases diagnosed with sand impaction were investigated. The size of the mineral opacity indicative of sand in the abdomen was measured and graded according to a previously published protocol based on height and length. Location, homogeneity, opacity and number of sand accumulations were also recorded.</p> <p>Results</p> <p>Twenty out of 30 control horses (66%) had one or more sand accumulations. In the present study; height, length and homogeneity of the accumulations were useful parameters for establishing a diagnosis of sand colic. Radiographically defined intestinal sand accumulation grades of up to 2 was a common finding in horses with no clinical signs from the gastrointestinal tract whereas most of the clinical cases had much larger grades, indicating larger sand accumulations.</p> <p>Conclusion</p> <p>Further work to establish a reliable grading system for intestinal sand content is warranted, but a previously proposed grading system based on measurements of height and length may be an alternative for easy assessment of sand accumulations in the meantime. The present study indicates that a grade 1 – 2 sand accumulation in the intestine is a frequent finding in horses. When working up a case with clinical signs from the gastrointestinal tract, one or more accumulations of this grade should not be considered the cause until other possibilities have been ruled out.</p

Matrix-Bound Growth Factors are Released upon Cartilage Compression by an Aggrecan-Dependent Sodium Flux that is Lost in Osteoarthritis

Articular cartilage is a dense extracellular matrix-rich tissue that degrades following chronic mechanical stress, resulting in osteoarthritis (OA). The tissue has low intrinsic repair especially in aged and osteoarthritic joints. Here, we describe three pro-regenerative factors; fibroblast growth factor 2 (FGF2), connective tissue growth factor, bound to transforming growth factor-beta (CTGF-TGFβ), and hepatoma-derived growth factor (HDGF), that are rapidly released from the pericellular matrix (PCM) of articular cartilage upon mechanical injury. All three growth factors bound heparan sulfate, and were displaced by exogenous NaCl. We hypothesised that sodium, sequestered within the aggrecan-rich matrix, was freed by injurious compression, thereby enhancing the bioavailability of pericellular growth factors. Indeed, growth factor release was abrogated when cartilage aggrecan was depleted by IL-1 treatment, and in severely damaged human osteoarthritic cartilage. A flux in free matrix sodium upon mechanical compression of cartilage was visualised by 23Na -MRI just below the articular surface. This corresponded to a region of reduced tissue stiffness, measured by scanning acoustic microscopy and second harmonic generation microscopy, and where Smad2/3 was phosphorylated upon cyclic compression. Our results describe a novel intrinsic repair mechanism, controlled by matrix stiffness and mediated by the free sodium concentration, in which heparan sulfate-bound growth factors are released from cartilage upon injurious load. They identify aggrecan as a depot for sequestered sodium, explaining why osteoarthritic tissue loses its ability to repair. Treatments that restore matrix sodium to allow appropriate release of growth factors upon load are predicted to enable intrinsic cartilage repair in OA

Tectonic evolution of the southern margin of the Amazonian craton in the late Mesoproterozoic based on field relationships and zircon U-Pb geochronology

New U-Pb zircon geochronological data integrated with field relationships and an airborne geophysical survey suggest that the Nova Brasilândia and Aguapeí belts are part of the same monocyclic, metaigneous and metasedimentary belt formed in the late Mesoproterozoic (1150 Ma-1110 Ma). This geological history is very similar to the within-plate origin of the Sunsás belt, in eastern Bolivia. Thus, we propose that the Nova Brasilândia, Aguapeí and Sunsás belts represent a unique geotectonic unit (here termed the Western Amazon belt) that became amalgamated at the end of the Mesoproterozoic and originated through the reactivation of a paleo-suture (Guaporé suture zone) in an intracontinental rift environment. Therefore, its geological history involves a short, complete Wilson cycle of ca. 40 Ma. Globally, this tectonic evolution may be related with the final breakup of the supercontinent Columbia. Mafic rocks and trondhjemites in the northernmost portion of the belt yielded U-Pb zircon ages ca. 1110 Ma, which dates the high-grade metamorphism and the closure of the rift. This indicates that the breakup of supercontinent Columbia was followed in short sequence by the assembly of supercontinent Rodinia at ca. 1.1-1.0 Ga and that the Western Amazon belt was formed during the accretion of the Arequipa-Antofalla basement to the Amazonian craton

Crustal recycling by subduction erosion in the central Mexican Volcanic Belt

Recycling of upper plate crust in subduction zones, or ‘subduction erosion’, is a major mechanism of crustal destruction at convergent margins. However, assessing the impact of eroded crust on arc magmas is difficult owing to the compositional similarity between the eroded crust, trench sediment and arc crustal basement that may all contribute to arc magma formation. Here we compare Sr–Nd–Pb–Hf and trace element data of crustal input material to Sr–Nd–Pb–Hf–He–O isotope chemistry of a well-characterized series of olivine-phyric, high-Mg# basalts to dacites in the central Mexican Volcanic Belt (MVB). Basaltic to andesitic magmas crystallize high-Ni olivines that have high mantle-like 3He/4He = 7–8 Ra and high crustal δ18Omelt = +6.3–8.5‰ implying their host magmas to be near-primary melts from a mantle infiltrated by slab-derived crustal components. Remarkably, their Hf–Nd isotope and Nd/Hf trace element systematics rule out the trench sediment as the recycled crust end member, and imply that the coastal and offshore granodiorites are the dominant recycled crust component. Sr–Nd–Pb–Hf isotope modeling shows that the granodiorites control the highly to moderately incompatible elements in the calc-alkaline arc magmas, together with lesser additions of Pb- and Sr-rich fluids from subducted mid-oceanic ridge basalt (MORB)-type altered oceanic crust (AOC). Nd–Hf mass balance suggests that the granodiorite exceeds the flux of the trench sediment by at least 9–10 times, corresponding to a flux of ⩾79–88 km3/km/Myr into the subduction zone. At an estimated thickness of 1500–1700 m, the granodiorite may buoyantly rise as bulk ‘slab diapirs’ into the mantle melt region and impose its trace element signature (e.g., Th/La, Nb/Ta) on the prevalent calc-alkaline arc magmas. Deep slab melting and local recycling of other slab components such as oceanic seamounts further diversify the MVB magmas by producing rare, strongly fractionated high-La magmas and a minor population of high-Nb magmas, respectively. Overall, the central MVB magmas inherit their striking geochemical diversity principally from the slab, thus emphasizing the importance of continental crust recycling in modern solid Earth relative to its new formation in modern subduction zones