Study of the degradation performance (TOC, BOD, and toxicity) of bisphenol A by the photo-Fenton process.

Degradation of bisphenol A (BPA, 0.5 L, 30 mg L-1) was studied by photo-Fenton treatment, while Fenton reagents were variables. The efficiency of the degradation process was evaluated by the reduction of total organic carbon (TOC), the biochemical oxygen demand (BOD), and toxicity. For toxicity analysis, bacterial methods were found infeasible, but the in vitro assay of VERO cells culture was successfully applied. Experiments according to a 22 design of experiments (DOE) with star points and three center points for statistical validity allowed selecting those process conditions (Fe(II) and H2O2 load) that maximized the process performance. Photo-Fenton process effectively eliminated BPA and partly degraded its by-products (residual TOC <15 %) under substoichiometric H2O2 dose (100.62 mg L-1) and at least 4 mg L-1 Fe(II), after a 90-min treatment. All treated samples were at least partially biodegradable. The cytotoxic concentration (LD50) of BPA for VERO cells was 7 mg L-1. With small H2O2 amount (15.24 mg L-1), only low BPA mineralization (TOC = 92 %) was attained. Toxicity was also detected to 50 % of cellular mortality even at long reaction times. However, 40.25 mg L-1 of H2O2 decreased residual TOC to 70 % while cell mortality decreased down to 25 %. With more H2O2, the residual TOC decreased down to 15 % but cell mortality remained within the 20-25 % level. Photo-Fenton increased the biodegradability and reduced the toxicity of the studied sample.

Short- to mid-term results of metallic press-fit radial head arthroplasty in unstable injuries of the elbow.

We assessed the short- to mid-term survival of metallic press-fit radial head prostheses in patients with radial head fractures and acute traumatic instability of the elbow. The medical records of 42 patients (16 males, 26 females) with a mean age of 56 years (23 to 85) with acute unstable elbow injuries, including a fracture of the radial head requiring metallic replacement of the radial head, were reviewed retrospectively. Survival of the prosthesis was assessed from the radiographs of 37 patients after a mean follow-up of 50 months (12 to 107). The functional results of 31 patients were assessed using range-of-movement, Mayo elbow performance score (MEPS), Disabilities of the Arm, Shoulder and Hand (DASH) score and the RAND 36-item health survey. At the most recent follow-up 25 prostheses were still well fixed, nine had been removed because of loosening, and three remained implanted but were loose. The mean time from implantation to loosening was 11 months (2 to 24). Radiolucent lines that developed around the prosthesis before removal were mild in three patients, moderate in one and severe in five. Range of movement parameters and mass grip strength were significantly lower in the affected elbow than in the unaffected side. The mean MEPS score was 86 (40 to 100) and the mean DASH score was 23 (0 to 81). According to RAND-36 scores, patients had more pain and lower physical function scores than normal population values. Loosening of press-fit radial head prostheses is common, occurs early, often leads to severe osteolysis of the proximal radius, and commonly requires removal of the prosthesis.

Regulated sarcolemmal localization of the muscle-specific ClC-1 chloride channel.

The skeletal muscle-specific ClC-1 is a voltage-gated chloride channel protein. Specific antibodies against ClC-1 revealed in muscle sections a sarcolemmal staining that was absent in the myotonic arrested development of righting response (ADR) mouse muscle. The intensity of the sarcolemmal staining varied from one type of muscle to another and in lateral sections showed a typical mosaic pattern that colocalized with beta-dystroglycan and left the transverse tubule openings clear. Surprisingly, in isolated myofibers, the ClC-1 protein was absent from the sarcolemma. Instead, it localized to intracellular I band areas as soon as the myofibers were isolated. When the isolated myofibers were incubated with the kinase inhibitor staurosporine, the ClC-1 protein shifted back to the sarcolemma. Electric stimulation of the cultivated fibers had a similar effect. Also, myofibers infected with a recombinant Semliki Forest virus (SFV) expressing myc-tagged ClC-1 showed intracellular localization of the protein. The virally expressed mycClC-1 reached the Golgi apparatus but sarcolemmal staining remained nondetectable, and addition of staurosporine into the growth medium recruited the mycClC-1 to the sarcolemma. These data indicate that sarcolemmal targeting of the ClC-1 requires specific signals that are provided by the physiological environment.

Endocytosis in skeletal muscle fibers.

Defining the organization of endocytic pathway in multinucleated skeletal myofibers is crucial to understand the routing of membrane proteins, such as receptors and glucose transporters, through this system. Here we analyzed the organization of the endocytic trafficking pathways in isolated rat myofibers. We found that sarcolemmal-coated pits and transferrin receptors were concentrated in the I band areas. Fluid phase markers were taken up into vesicles in the same areas along the whole length of the fibers and were then delivered into structures around and between the nuclei. These markers also accumulated beneath the neuromuscular and myotendinous junctions. The recycling compartment, labeled with transferrin, appeared as perinuclear and interfibrillar dots that partially colocalized with the GLUT4 compartment. Low-density lipoprotein, a marker of the lysosome-directed pathway, was transported into sparsely distributed perinuclear and interfibrillar dots that contacted microtubules. A majority of these dots did not colocalize with internalized transferrin, indicating that the recycling and the lysosome-directed pathways were distinct. In conclusion, the I band areas were active in endocytosis along the whole length of the multinucleated myofibers. The sorting endosomes distributed in a cross-striated fashion while the recycling and late endosomal compartments showed perinuclear and interfibrillar localizations and followed the course of microtubules.

Degradation of exogenous MBP by myelin Ca(2+)-activated neutral protease and effect of extraction of myelin on enzyme activity.

Time-course of degradation of exogenous myelin basic protein (MBP) by myelin calcium-activated neutral protease (CANP) and the effect of different treatments with organic solvents and salt solutions on CANP activity were studied. Activity was estimated from the supernatants of incubation mixtures as primary amino groups released during proteolysis by a spectrophotometric method or from the protein patterns on SDS gels. Analysis of the time-course of bovine 18.3 K MBP proteolysis revealed a defined sequence of degradation, at least twelve peptides being observed. Bovine and mouse myelin CANPs degraded both bovine 18.3 K MBP and mouse 14.0 K MBP in a similar manner. On SDS gels the banding patterns of degradation of these proteins revealed differences as well as similarities. Delipidation of myelin with acetone did not affect on myelin CANP activity. Removal of lipid with ether:ethanol (3:2) slightly reduced activity, and after chloroform:methanol (2:1) extraction the residue had no CANP activity. The activity could not be established in the chloroform-methanol supernatant either. These findings together with extraction experiments with buffered salt solutions suggest that the enzyme molecule is tightly bound in the membrane interior and may require certain myelin lipids for activity. Analysis of the time-course experiment suggests that MBP in the membrane-bound form acts as a substrate for CANP, and soluble degradation products are released from the membrane.