Objective:To investigate the effect of local application of the water soluble protein fraction,containing specific egg yolk antibody,on the recolonization of Streptococcus mutans.Methods:Whole cells of inactivated streptococcus mutans were used as antigen to immunize bens,then water soluble protein fraction(WSF) was extracted from the eggs. Mouth wash containing 0.1 mg/ml of WSF was prepared and administered to 8 volunteers.The mouth wash was used once every two days for 2 weeks.Vehicle solution was used in other 6 volunteers as the control.S.mutans in saliva was monitored for 100 days.Results:Before using the mouth washes,S.mutans level in saliva of the volunteers was 36.4%.S.mutans was removed by hibitane,it kept less than 3% in 100 days in the tested individuals,while 23%～37% in the controls.Conclusion:The WSF containing specific egg yolk antibody can effectively prevent the recolonization of streptococcus mutans.

BACKGROUND:Whether lumbar spondylolisthesis needs to be treated with reduction remains controversial.OBJECTIVE:To investigate the clinical effectiveness of pedicle screw fixation combined with posterior lumbar interbody fusion for degenerative lumbar spondylolisthesis in the patients aged more than 70 years old.METHODS:The clinical data of 30 patients with degenerative spondylolisthesis aged over 70 years old undergoing pedicle screw fixation combined with posterior lumbar interbody fusion were analyzed retrospectively.The Visual Analogue Scale,Oswestry Dysfunction Index and the Japan Orthopedics Association scores were compared and analyzed before and after surgery.RESULTS AND CONCLUSION:(1) Among 30 patients,12 were male and 18 female,the average age was (75.1±6.7) years old,and all were followed up for more than 12 months.(2) The postoperative Visual Analogue Scale,Oswestry Dysfunction Index and the Japan Orthopedics Association scores were significantly improved compared with baseline (P ＜ 0.05).According to the Japan Orthopedics Association scores,3 cases were cured,24 were significantly effective,and 3 effective.(3) Graft fusion was achieved at all patients,the average fusion time was (5.13±0.65) months.(4) The average operation time was (225.6±23.4) minutes,the average intraoperative blood loss was (470±45.5) mL,and the average follow-up time was (25.8±3.5) months.(5) Six patients presented complications (20％),including one case of dural tear,two cases of paralytic intestinal obstruction,and three transient lower extremity nerve symptoms.(6) These results indicate that if the associated disorders are strictly controlled,pedicle screw fixation combined with posterior lumbar interbody fusion can achieve good surgical results in the treatment of degenerative spondylolisthesis in the elderly.