ABSTRACT
Diabetes mellitus is a risk factor for various types of tendon disorders. The mechanisms underlying diabetes associated tendinopathies remain unclear, but typically, systemic factors related to high blood glucose levels are thought to be causally involved. We hypothesize that tendon immanent cells might be directly involved in diabetic tendinopathy. We therefore analyzed human and rat tendons by immunohistochemistry, laser capture microdissection, and single cell PCR for pancreatic ß-cell associated markers. Moreover, we examined the short term effects of a single injection of streptozotocin, a toxin for GLUT2 expressing cells, in rats on insulin expression of tendon cells, and on the biomechanical properties of Achilles tendons. Tendon cells, both in the perivascular area and in the dense collagenous tissue express insulin and Glut2 on both protein and mRNA levels. In addition, glucagon and PDX-1 are present in tendon cells. Intraperitoneal injection of streptozotocin caused a loss of insulin and insulin mRNA in rat Achilles tendons after only 5 days, accompanied by a 40% reduction of mechanical strength. In summary, a so far unrecognized, extrapancreatic, insulin-producing cell type, possibly playing a major role in the pathophysiology of diabetic tendinopathy is described. In view of these data, novel strategies in tendon repair may be considered. The potential of the described cells as a tool for treating diabetes needs to be addressed by further studies.
Subject(s)
Insulin-Secreting Cells/metabolism , Insulin-Secreting Cells/pathology , Insulin/biosynthesis , Tendons/pathology , Achilles Tendon/metabolism , Achilles Tendon/pathology , Adult , Aged , Animals , Blotting, Western , Diabetes Mellitus/pathology , Female , Glucose/pharmacology , Humans , Immunohistochemistry , Insulin/metabolism , Insulin Secretion , Insulin-Secreting Cells/drug effects , Male , Middle Aged , Rats , Young AdultABSTRACT
The incidence of proximal humerus fractures is rising and they constitute the third most frequent fracture in the elderly after femoral fractures in the hip area and radius fractures. They are caused by the age-related increase in osteoporosis. In contrast to young people, low-energy trauma involved in simple falls represents the mechanism that leads to the injury in older people. Numerous authors have introduced systems for the classification of proximal humerus fractures.After a thorough clinical examination of the affected extremity including assessment of circulation, motor function, and sensitivity, attention should be directed toward concomitant injuries, especially in the region of the shoulder girdle and thorax. Advocated imaging consists of anteroposterior and axial views of the affected shoulder. Disagreement over management of this fracture is quite considerable and treatment ranges from a conservative approach through to procedures for minimally invasive plate osteosynthesis, open fixed-angle locked plating, and nailing up to prosthetic replacement.
