ABSTRACT
Complete avulsion of hip abductor muscles may cause severe gait dysfunction and pain. An open surgical procedure to transfer tendons of the gluteus maximus and the tensor fasciae latae to the greater trochanter to make up for the deficient hip abductor has been proposed. The purpose of this study was to describe an endoscopic procedure to transfer gluteus maximus and the tensor fasciae latae to the greater trochanter for hip abductor deficiency.
ABSTRACT
Arthroscopic release of the iliopsoas tendon for iliopsoas impingement (IPI) after total hip arthroplasty (THA) at the lesser trochanter gives good results. However, where IPI then recurs, due to adhesions between the healing iliopsoas tendon and the surrounding soft tissue, and nonoperative measures have failed, a revision THA procedure is usually considered. We propose a technique of arthroscopic visualization of the recurrent IPI and a subsequent psoas tenotomy at the level of the hip joint using an outside-in capsulotomy approach. This secondary tenotomy, located proximally directly at the level of the recurrent impingement, allows relief of the painful symptoms without compromising the muscle function of the iliopsoas and precludes the need for a complex THA revision.
Subject(s)
Hand Deformities, Acquired/surgery , Leprosy/complications , Tendon Transfer/methods , Adult , Hand Deformities, Acquired/etiology , Hand Deformities, Acquired/microbiology , Humans , Male , Ulnar Nerve/microbiology , Ulnar Nerve/pathology , Ulnar Neuropathies/microbiology , Ulnar Neuropathies/pathologyABSTRACT
Pore formation in the apical membrane of the midgut epithelial cells of susceptible insects constitutes a key step in the mode of action of Bacillus thuringiensis insecticidal toxins. In order to study the mechanism of toxin insertion into the membrane, at least one residue in each of the pore-forming-domain (domain I) interhelical loops of Cry1Aa was replaced individually by cysteine, an amino acid which is normally absent from the activated Cry1Aa toxin, using site-directed mutagenesis. The toxicity of most mutants to Manduca sexta neonate larvae was comparable to that of Cry1Aa. The ability of each of the activated mutant toxins to permeabilize M. sexta midgut brush border membrane vesicles was examined with an osmotic swelling assay. Following a 1-h preincubation, all mutants except the V150C mutant were able to form pores at pH 7.5, although the W182C mutant had a weaker activity than the other toxins. Increasing the pH to 10.5, a procedure which introduces a negative charge on the thiol group of the cysteine residues, caused a significant reduction in the pore-forming abilities of most mutants without affecting those of Cry1Aa or the I88C, T122C, Y153C, or S252C mutant. The rate of pore formation was significantly lower for the F50C, Q151C, Y153C, W182C, and S252C mutants than for Cry1Aa at pH 7.5. At the higher pH, all mutants formed pores significantly more slowly than Cry1Aa, except the I88C mutant, which formed pores significantly faster, and the T122C mutant. These results indicate that domain I interhelical loop residues play an important role in the conformational changes leading to toxin insertion and pore formation.
Subject(s)
Bacillus thuringiensis/genetics , Bacterial Proteins/genetics , Bacterial Proteins/toxicity , Endotoxins/genetics , Endotoxins/toxicity , Epithelial Cells/drug effects , Hemolysin Proteins/genetics , Hemolysin Proteins/toxicity , Intestinal Mucosa/drug effects , Manduca/drug effects , Microvilli/drug effects , Mutation, Missense , Transport Vesicles/drug effects , Amino Acid Substitution/genetics , Animals , Bacillus thuringiensis Toxins , Bacterial Proteins/chemistry , Bacterial Proteins/metabolism , Endotoxins/chemistry , Endotoxins/metabolism , Hemolysin Proteins/chemistry , Hemolysin Proteins/metabolism , Humans , Hydrogen-Ion Concentration , Larva/drug effects , Models, Molecular , Mutagenesis, Site-Directed , Permeability/drug effects , Protein Structure, TertiaryABSTRACT
The objective of the present work was to create an active Cry1Aa toxin showing enhanced resistance to degradation by spruce budworm (Choristoneura fumiferana) midgut proteases by mutating potential chymotrypsin and trypsin sites. Fourteen Cry1Aa mutants were created in an Escherichia coli-Bacillus shuttle vector and expressed in a crystal minus Bacillus thuringiensis host. Using spruce budworm gut juice, commercial bovine trypsin and chymotrypsin we performed protease resistance assays with Cry1Aa wild type and mutant toxins. Although many mutants showed little or no change, several mutants showed a > 2-fold increase (R543S, R566G, and F570S) up to a > 4-fold increase in toxicity (F576S), in bioassay studies against C. fumiferana. The in vitro protease resistance assay results indicated a possible involvement of other gut juice components in toxin overdigestion.
