| Part I Establishment of Rabbit Pyogenic Spondylitis ModelObjective:Establish rabbit pyogenic spondylitis model.Methods:Take 12 male New Zealand white rabbits, randomly divide into 4 groups and inject staphylococcus aureus suspension fluid with different concentration. Surgical approach selects anterolateral retroperitoneal approach. During the operation, exposure intervertebral space of rabbit spinal L1/2 and L5/6, remove part of intervertebral disc, destruct adjacent vertebral endplates, and then input the staphylococcus aureus suspension fluid with different concentration into destructed intervertebral space.2 weeks after the operation, draw venous blood for culturing and sacrifice the animal, take bone tissue of the surgical site and the liver for bacterial culturing, and take pathological examination to the bone tissue of the surgical site.Result:Apply the staphylococcus aureus suspension fluid with the concentration of 102 CFU/ml to successfully induce spinal infection in 100%(8/8) planting site, the result of liver and blood culturing is negative, rule out the possibility of systemic infection. Apply the staphylococcus aureus suspension fluid with the concentration of 10CFU/ml to successfully induce spinal infection in 33%(2/6) planting area, Apply the staphylococcus aureus suspension fluid with the concentration of lOCFU/ml to successfully induce spinal infection in 100%(6/6) planting area, but only 2 experimental animals separately die 7 and 11 days after the operation.Conclusion:It has successfully established appropriate rabbit pyogenic spondylitis model, which can be applicable to efficacy comparison of different anti-infection strategies.Part II Experimental Study on Nano Silver Local Reserved Injection Treatment Rabbit Pyogenic SpondylitisObjective:Discuss efficacy of Nano siiver treatment pyogenic spondylitis.Materials & Methods:Take 24 New Zealand white rabbits; randomly divide into blank control group and experimental group A & B, make spinal infection model in accordance with the aforesaid methods, meanwhile indwell drug control guide in the surgical site during the operation. Since the first day after the operation, conduct local drug every day, inject 0.1mg/Kg Nano silver solution to Experimental Group A, inject 1mg/Kg Nano silver solution to Experimental Group B, and inject saline to Blank Control Group. After 2 weeks of consecutive drugging, draw venous blood for culturing and sacrifice the animal, take bone tissue of the surgical site for pathological examination and culturing, and take the liver tissue for culturing. Before sacrificing the animals, take spinal X-ray and CT examination and observe the changes of medical imageology.Result:The bacteria culturing result of bone tissues in the inoculated site shows that the positive infection rate of Experimental Group A is 75%(6/8), zero death; the positive infection rate of Experimental Group B is 25%(2/8), zero death; the positive infection rate of Blank Control Group is 100%,1 death,2 cases paralysis of both lower extremities. The comparison of positive infection rate result of Experimental Group B and Blank Control Group has statistical difference (P＜0.01), as well as Experimental A and Blank Control Group (P＜0.01), which confirms the effectiveness of Nano silver local reserved drug.X-ray and CT examination indicate that the infectious animal bacterination partly has the changes involving bond destruction, bone mineral density increasing, and intervertebral space stenosis, and the uninfected animals have no abnormal structural change. The corresponding disease examination results further verify the imageology and animal centrum bone tissue of cultivating the positive have the changes of typical pyogenic osteomyelitis. The bone marrow tissue dissolves and necrotizes, the marrow cavity has pyogenic exudations and necrosis substances, the bone cells necrotize in quantity, the osteogenic activities reduce, and the sequestrum forms with the inflammatory granulation tissue around. Conclusion:It is effective to apply Nano silver solution for treating the spinal column infection partly. The antibiotic action of Nano silver solution in the internal environment of the body shows the positive correlation with the dose concentration. But it is not decisive that Nano silver partly dosing treats the spinal column infection, which cannot verify this dosing method shall replace for the application antibiotic of the whole body.Part III Biological Distribution of Nano Silver in the Body of the AnimalObjective:Analyze the distribution conditions of Nano sliver in the body of the animal preliminarily.Methods and Materials:Take the venous blood, liver, kidney, spleen, spinal cord, and testis organs specimen of the animals in Part II of the experiment. The grouping is the same as Part II of the experiment, involving 0.1 mg/Kg group,1 mg/Kg group and blank control group. Adopt the nitric acid-perchloric acid chemical digestion method, digest the specimen to be tested into the liquid state, and measure Ag content of the tissue with the atomic absorption method upon the constant volume. Make the liver, kidney, spleen, spinal cord, and testis paraffin section specimen as the histology examination and observe whether it has the pathologic change. Make the spinal marrow ultra thin section and observe with the transmission electron microscopy.Results:1 mg/Kg Nano silver solution group measures the silver content sequences of each tissue as spinal cord> spleen> kidney> testis> liver> blood serum, and as for 0.1 mg/kg group, the silver content sequences of each tissue is spinal cord> kidney> spleen> liver> testis> blood serum. The silver content differences of the blood serum in two experimental groups and control group have no statistics significance (P>0.05). The silver content differences of the spinal marrow tissue in two experimental groups and control group have the statistics significance (P<0.01). The silver content differences of liver, kidney, spleen and testis in 1 mg/Kg experimental group and control group have the statistics significance (P<0.05). The silver content differences of liver, kidney, spleen and testis in 0.1 mg/Kg experimental group and control group have no statistics significance (P＜0.05). The result indicates that 1 mg/Kg Nano silver group produces the accumulation in spinal cord, liver, kidney, spleen and testis tissues except for the blood serum, and 0.1 mg/Kg Nano silver group only produces the accumulation in spinal cord tissue. The histology examination of spinal cord, liver, kidney, spleen and testis of two experimental groups has no obvious pathological change.Conclusion:Nano silver solution is safe and effective by the way of partly retaining for dosing, however, the dose shall accumulate in the body of the animal after reaching the established limit values. The accumulating process is accomplished mainly through the transfer of hemolymph system and direct jump of the part. The most obvious target tissue of the accumulative action is the peripheral tissue (spinal cord) and immune organ (spleen). The micro accumulation shall not result in the organic and functional damages of the tissue and organ.
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