The effect of fibroblasts, vascular smooth muscle cells, and pericytes on sprout formation of endothelial cells in a fibrin gel angiogenesis system.

We have recently shown that during angiogenesis in situ, sprouting and newly formed capillaries appear to be composed of two cell types, endothelial cells and nonendothelial, pericyte-like cells. The effect of pericytes on the process of neovessel formation is largely unknown. To study the influence of nonendothelial cell types on endothelial tubule formation, we have performed coculture experiments in a fibrin-clot angiogenesis system. When seeded below a critical density on the surface of fibrin gels, endothelial cells (from macro- or microvascular origin) did not show spontaneous formation of sprouts. However, in superconfluent cell cultures or after stimulation of endothelial cells with basic fibroblast growth factor (bFGF), endothelial cells frequently acquired an elongated shape. By stimulation of endothelial cells with both bFGF and vascular endothelial growth factor (VEGF), development of short capillary-like structures was induced. When endothelial cells were cocultivated with a cell type of high fibrinolytic potential, i.e., fibroblasts, development of capillary-like formations could not be detected. Cocultivation of endothelial cells with vascular smooth muscle cells or with retinal pericytes also did not increase the number of capillary-like formations in fibrin gels. In contrast, vascular smooth muscle cells on their own could be demonstrated to give rise to branched capillary-like networks in fibrin, which easily could be mistaken for true capillaries. Our results indicate that periendothelial cells contribute to angiogenesis not only by fibrinolysis and proteolytic permeation of the extracellular matrix. Rather, the interactions of endothelial cells and pericyte-like cells, as frequently observed during neovessel formation in situ, appear to be more specific and may require factors hitherto unknown.

[Instability problems of the spine in sports]. / Instabilitätsprobleme der Wirbelsäule im Sport.

In modern competitive sports the vertebral column is increasingly subjected to maximum stress. This has led to lasting damage especially in young competitive sportsmen in whom the vertebral column had not yet developed to full maturity. Back pain can be more successfully analysed in respect of its causes by means of the additional use of the knowledge and examination methods of manual medicine. Emphasis is placed in this article on the importance of such pain as an early symptom of ligamentous instability. Therapeutic recommendations are given.

Changes of the elastin compartment in the human meniscus.

We report on the elastin, collagen and ground substance compartments in the human meniscus and their interrelationships. Elastin is found in neonates and shows both an arrangement parallel to the collagen fibre and into net-like structures. Branching, caliber inconstancy, rupture and the phenomenon of the "rubber band" are findings within the different forms of the meniscopathy. The function of the elastin compartment cannot be visualised without suggesting "puncta fixa". The morphology of the collagen-elastin-junctions has been described and their possible mode of function is discussed with the help of a model.

[Resection arthrodesis in the treatment of bone tumors located near the knee joint (author's transl)]. / Resektionsarthrodesen in der Behandlung kniegelenknaher Knochentumoren

First of all the authors limit the indications to resection arthrodesis in bone tumors located near the knee joint and present the main features of the procedure. These consist of the technical requirements for a radical operation, the type of osteosynthesis with special supports and the type of compensation for the defect. Based on the well known surgical techniques of Juvara, Merle d'Aubigné and J.Böhler, a precedure was presented which has been clinically tested for 6 years. In this procedure which is based on individual locations of tumors, a homologous bone canal helps to compensate the resection defect. The biological characteristic of the healing of this interponate was described. Finally, recommendations for postoperative aftercare were presented whereby the long support in orthopedic apparatus and the renewed spongiosa accumulation as a result of the removal of the metal were mentioned.

[A case of fatigue fracture at the border between tibial head and shaft after removal of a small corticocancellous graft (author's transl)]. / Zur Ermüdungsfraktur an der Schienbeinkopfschaftgrenze nach Entnahme eines kleinen kortikospongiösen Spanes

Report on a case. Causes were: 1. faulty technique of removing graft. 2. Osteoporosis due to immobilisation in plaster after several previous operations. 3. functional overloading with mechanical after-treatment. The need for a proper technique of removing the graft - particularly for the operation after Maquet - is once more emphasized.