Hydrolysis of casein from different sources by immobilized trypsin on biochar: Effect of immobilization method.

The present study aimed to evaluate the effect of the immobilization method of trypsin on biochar on the hydrolysis of casein from different sources, when compared to the process using trypsin in native form, to obtain bioactive peptides. The modification of the surface of biochar with glutaraldehyde was effective, as shown by the results of FTIR assay and the texture profile of the materials. Both activated and functionalized biochar showed high immobilization efficiency (greater than 87%) and high binding capacity (greater than 91 mg/g). During hydrolysis, the biocatalyst obtained by enzyme immobilization on the functionalized biochar presented a higher hydrolysis capacity for the different caseins when compared to the enzyme immobilized by adsorption, with values of 3.05 and 2.73 U/mg for goat casein, 2.36 and 1.85 U/mg for bovine casein, and 2.60 and 2.37 U/mg for buffalo, casein, respectively, with 60 min of reaction. The results of inhibitory activity in this study ranged from 93.5% and 25.5% for trypsin in its free form and immobilized on functionalized activated carbon, respectively, under the same reaction conditions. The immobilization methods were efficient, presenting high immobilization capacity. The proteolytic activity of trypsin immobilized via covalent binding was higher when compared the immobilization by adsorption. Thus, the functionalized biochar has proven to be potential support for enzyme immobilization, and the biocatalyst can be reused for more than 4 cycles. Despite lower ACE inhibition values of hydrolyzed obtained with the immobilized enzymes compared to free enzymes, biocatalysts present advantage due to the possibility of reuse.

Short-term results of hydroxyapatite-coated primary total hip arthroplasty.

One hundred consecutive patients who had Howmedica ABG total hip replacements, a system in which the femoral stem and the acetabular component are hydroxyapatite coated, during the period from September 1989 to January 1991 were studied prospectively. Clinical assessment using the d'Aubigné score showed that 96 patients had an excellent score at a minimum of 2 years from the operation. Radiographic analysis, based on DeLee and Charnley criteria for the acetabular cup and on Gruen criteria for the femoral stem, showed equally good results. There was good initial stability of the cup and the metaphyseal portion of the stem, with a secondary increase of load transmission in Zones 2 and 6 with cortical and cancellous thickening.

[In vitro biocompatibility: increase in the capacity for adhesion in fibroblasts by materials pretreated with fibronectin]. / Biocompatibilita' in vitro: aumento della capacita' di adesione dei fibroblasti a materiali pretrattati con fibronectina (FN).

The Authors expose their observations about the fibroblasts adhesion to materials used as implants in orthopaedic surgery; the first part of the experiment uses normal culture conditions. In the second part the materials have been pre-coated with Fibronectin (FN), a glycoprotein involved in cell-to-substratum adhesion Fibroblasts adhesion increases about 30-40% with pre-coated materials. This observation is important for comprehension of adhesion mechanisms in a multidisciplinary approach to biocompatibility of implant materials.