Preliminary results comparing two methods of lateral column lengthening.

Forty-five patients (49 feet) underwent lateral column lengthening as treatment for painful pes planus. Twenty-five patients (27 feet) were available for both radiographic and clinical evaluation at least one year postoperatively. Of these 25 patients, 10 feet underwent Evans opening wedge osteotomy with tricortical iliac crest bone graft; 17 feet underwent calcaneocuboid distraction arthrodesis utilizing iliac crest bone graft. In addition, both groups underwent debridement of the posterior tibial tendon combined with transfer of the flexor digitorum longus into the navicular for reinforcement. Radiographic results documented marked improvement in all parameters. There was more improvement in the calcaneocuboid fusion group than the osteotomy group, but the difference was not statistically significant. Postoperative AOFAS rating scores averaged 87.9 for the osteotomy group and 80.9 for the distraction arthrodesis group. The difference was not statistically significant. Twenty of 25 patients (83.5%) in both groups were very satisfied. Twenty-four of 25 patients (96%) stated that knowing the final result they would have the same surgery again. Complications were reported for 32 patients (34 feet). Both the Evans opening wedge calcaneal osteotomy and calcaneocuboid distraction arthrodesis offer significant improvement in the radiographic parameters and AOFAS clinical scores for patients with painful, flexible flatfoot deformity. However, the complication rate remains high with both methods, and the rate of nonunion and delayed union with the calcaneocuboid distraction arthrodesis method remains a significant problem with this technique.

Parameters for detection of mutagenesis of 1,2-dimethylhydrazine using an in vitro Bacillus subtilis system.

Parameters for detection of mutagenesis of 1,2-dimethylhydrazine (DMH) using a Bacillus subtilis microbial assay are defined. His+ and his met mutations were induced in B. subtilis TKJ6321 in the absence of rat liver S-9 Mix. This B subtilis mutant showed a greater sensitivity to this chemical than did Salmonella typhimurium TA1535. Protein-binding studies with bovine serum albumin showed the capacity for DMH to bind non-specifically to protein. S-9 mix from Aroclor pretreated animals appeared to decrease the mutagenic response. Kinetics of mutagen stability were also shown, thereby demonstrating the need for more complete investigation of known chemical carcinogens which give negative results in the Ames bioassay alone.

Mutagenicity and DNA-damaging activity for several pesticides tested with Bacillus subtilis mutants.

The active pure compounds of 4 pesticides were tested for DNA-damaging and mutagenic activity in Bacillus subtilis and Salmonella typhimurium tester strains. Included were zinc ethylenebisdithiocarbamate (dithane), 1,2-dihydropyridazine-3,6-dione (maleic hydrazide), O,O-dimethylphosphorodithioate (malathion), and 1,2-dibromoethane (fumazone). These agents gave either weak or negative mutagenic responses with the Salmonella/microsome tests for mutagenicity, but were all positive when the tester was B. subtilis strain TKJ6321. Of the 4 chemicals, only fumazone required metabolic activation with rat-liver S9 mix. Upon activation, it produced a volatile mutagenic product. Dithane, maleic hydrazide, and malathion were all mutagenic and did not require metabolic activation. Among these agents, dithane was strongly mutagenic while fumazone, maleic hydrazide and malathion were moderately mutagenic. Only dithane gave significant DNA-damaging activity when applied to a battery of repair-deficient B. subtilis mutants. For the chemicals reported, it is concluded that B. subtilis is superior to S. typhimurium in the detection of mutagenic activity. We strongly recommend its use for prescreening procedures in combination with the S. typhimurium testers.

DNA-damaging and mutagenic effects of 1,2-dimethylhydrazine on Bacillus subtilis repair-deficient mutants.

Mutagenic, DNA-damaging, and in vivo alteration of DNA have been demonstrated for 1,2-dimethylhydrazine (DMH), a potent inducer of adenocarcinomas of the large intestine and colon of rats. These activities are pH-dependent, with 6.5 giving optimum response. There was no requirement for metabolic activation with rat-liver S9 mix when the appropriate Bacillus subtilis mutant strains were used. The Rec- strains recA8 and mc-1 were greater than 300-fold more sensitive to the DNA-damaging activity of DMH than was their isogenic wild-type parent. The DNA isolated from DMH-treated mc-1 had altered spectroscopic characteristics, and gave a greatly reduced transformation efficiency. Treatment of B. subtilis strain TKJ6321 with DMH at pH 6.5 induced His+, Met+ mutations in substantial numbers at low concentrations of this chemical. The use of B. subtilis mutants in these studies has therefore made it possible to demonstrate mutagenic and DNA-damaging activity in bacteria for this potent carcinogenic chemical.