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A total of 14 women and seven men with a mean age of 43 years (18 to 68) who sustained a Mason type IV fracture of the elbow, without an additional type II or III coronoid fracture, were evaluated after a mean of 21 years (14 to 46). Primary treatment included closed elbow reduction followed by immobilisation in a plaster in all cases, with an additional excision of the radial head in 11, partial resection in two and suturing of the annular ligament in two. Delayed radial head excision was performed in two patients and an ulnar nerve transposition in one. The uninjured elbows served as controls. Nine patients had no symptoms, 11 reported slight impairment, and one severe impairment of the elbow. Elbow flexion was impaired by a mean of 3° (SD 4) and extension by a mean of 9° (SD 4) (p < 0.01). None experienced chronic elbow instability or recurrent dislocation. There were more degenerative changes in the formerly injured elbows, but none had developed a reduction in joint space. We conclude that most patients with a Mason type IV fracture of the elbow report a good long-term outcome.

Endocytosis of horseradish peroxidase was studiedin vivo in innervated mouse extensor digitorum longus and soleus muscles and in the same muscles 6 days after surgical denervation, by a combination of biochemical and morphological techniques. Biochemical determination of peroxidase activity in extensor digitorum longus and soleus muscles at different times after a single intravenous injection of horseradish peroxidase followed by extensive washing of the muscles, showed that peak levels of horseradish peroxidase in muscle tissue were obtained 2 h after injection. The uptake of horseradish peroxidase in denervated extensor digitorum longus and soleus muscles was approximately three times greater than in innervated control muscles. Light and electron microscopic examination of denervated and innervated extensor digitorum longus muscles, demonstrated that horseradish peroxidase was present in the extracellular space, i.e. between muscle fibers and in transverse tubules already 30 min after an intravenous horseradish peroxidase injection. Light-microscopic examination, 2–4 h after an intravenous injection of horseradish peroxidase, revealed that a population of denervated muscle fibers contained horseradish peroxidase in bodies or vacuoles restricted to segments of the fibers. Such bodies, containing horseradish peroxidase, were not observed in innervated muscle fibers. Ultrastructural examination showed that these horseradish peroxidase-bodies were limited by a single membrane and located adjacent to transverse tubules between myofibrils showing early signs of degeneration. Coated or uncoated vesicles of about 50–100 nm appeared to originate from horseradish peroxidase-labelled transverse tubules in denervated muscle fibers.

We describe a very efficient method for fluorescent labeling of acidic structures in denervated skeletal muscle with rhodamine B. Rhodamine B at 50 ng/ml gave selective and distinct segmental labeling of denervated muscle fibers after 5-min incubation at room temperature. Labeling was also achieved at 4 degrees C. The labeling was disrupted by the ionophores monensin and nigericin, suggesting a labeling confined to acidic structures. Rhodamine B co-localized with the lysosomotropic dye Lyso Tracker Green and a marker for endocytosis (fluorescein isothiocyanate-labeled dextran). Rhodamine B, which is highly lipophilic, showed pH-dependent fluorescence emission in saturated aqueous N-octanol. Tetramethylrhodamine showed similar characteristics for labeling of denervated muscle fibers and pH-dependent fluorescence in N-octanol. The carboxyl group present in these two compounds appears important, because structurally related compounds that either lack this group or have it esterified failed to label denervated muscle fibers and showed no pH-dependent fluorescence in N-octanol. The results suggest that rhodamine B labels acidic organelles belonging to the endosomal/lyosomal system of denervated skeletal muscle fibers. Nevertheless, it failed to label such organelles in a number of mammalian cell types other than denervated skeletal muscle fibers.

Summary Pinocytosis induced by Na+ was assayed by phase contrast microscopy in 8–12 days starvedAmoeba proteus. These cultures were inactive with respect to calcium-dependent Na+-induced pinocytosis, but treatment with amino acid methyl and ethyl esters increased their capacity for pinocytosis. Besides promoting pinocytosis these compounds also stimulated calcium-sensitive secretion of lysosomal enzymes from normal, 2–3 days starved, cells. Only uncharged 1-forms of the amino acid esters were effective. Also other lysosomotropic compounds including monodansylcadaverine, glycine-phenylalanine-2-naphthylamide, NH4Cl, and the ionophores monensin and A23187 activated starved cells. The effect of these agents (except A23187) was inhibited by the drug dantrolene suggesting that activation is a consequence of release of Ca2+ from intracellular stores. Several of the lysosomotropic agents also lost their activating effect in the presence of phospholipase A2 (PLA2) inhibitors. To investigate whether or not PLA2 activity in the cell culture could imitate the effect of the lysosomotropic agents, we incubated starved cells with snake venom PLA2s. These enzymes caused rapid, dantrolene-sensitive activation of the cells. Measurement of endogenous PLA2in “normal” cells revealed significant cellular activity but no significant secretion of the enzyme into the culture medium was observed. Together the studies with enzyme inhibitors and dantrolene suggest that the process by which lysosomotropic agents affect pinocytosis involves activation of PLA2 and release of Ca2+ from intracellular stores.

We have reviewed 20 women and three men aged 22 to 73 years, who had sustained a Mason type-IIb fracture of the neck of the radius 14 to 25 years earlier. There were 19 patients with displacement of the fractures of 2 mm to 4 mm, of whom 13 had been subjected to early mobilisation and six had been treated in plaster for one to four weeks. Of four patients with displacement of 4 mm to 8 mm, three had undergone excision and one an open reduction of the head of radius. A total of 21 patients had no subjective complaints at follow-up, but two had slight impairment and occasional elbow pain. The mean range of movement and strength of the elbow were not impaired. The elbows had a higher prevalence of degenerative changes than the opposite side, but no greater reduction of joint space.Mason type-IIb fractures have an excellent long-term outcome if operation is undertaken when the displacement of the fracture exceeds 4 mm.