In this study, the rate of bone formation and the pattern of bone to implant contact surface around HA coated implant and pure Ti implant inserted into the irradiated tibia of rabbit were compared. Sixteen mongrel mature male rabbits were used as experimental animal. Each rabbit received 15 Gy of irradiation. Four weeks after irradiation, two holes were prepared on the tibia of each rabbit for placement of HA coated type and pure Ti type implants. Prior to implant placement, one group received steroid irrigation and the control group was similarly irrigated with normal saline. This was immediately followed by placement of the two different types of implants. Postoperatively, tetracycline was injected intramuscularly for 3 days. For fluorescent labelling, 3 days of intramuscular alizarine red injection was given. 2 weeks before sacrifice, followed by intramuscular calcein green on the last 3 days before specimen collection. Each rabbit was sacrificed on the second, fourth, sixth and eighth week after the implantation. The specimens were observed by the light microscope and the fluorescent microscope. The results were as follows; 1. All implants inserted into the irradiated tibia of rabbit were free from clinical mobility and no signs of bony resorption were noted around the site of implant placement. 2. Under the light microscope, new bone formation proceeded faster around implants that received steroid irrigation compared to the control group irrigated with saline. Bone to implant contact surface was greater in the steroid irrigated group than the saline irrigated group. Therefore, better initial stabilization was observed in the group pretreated with steroid irrigation. 3. Under the light microscope. HA coated implants showed broader bone to implant contact surface than pure Ti implants, and HA coated implants had better bone healing pattern than pure Ti implants. 4. In the steroid pretreated group, acceleration of bone formation was demonstrated by fluorescent microscopy around the 2, 4 weeks group and the 6 weeks HA coated implant group. The difference in the rate of bone formation proved to be statistically significant (P<0.05). Faster bone formation was noted in the saline irrigated group in the 6 weeks pure Ti implants and 8 weeks group. The difference was not statistically significant(P<0.05). 5. For the rabbits that were sacrificed on the second and fourth week after the implant placements, the rates of bone formation around HA coated implants proceeded faster than those around pure Ti implants under the fluorescent microscopy. For the rabbits that were sacrificed on the sixth week after the implant placements, the rates of bone formation around pure Ti implants proceeded faster than those around HA coated implants under the fluorescent microscopy. But this result did not show statistical significance (P<0.05) For the rabbits that were sacrificed on the eighth week after the implant placements, the rates of bone formation around HA coated implants proceeded faster than those around pure Ti implants under the fluorescent microscopy. This result was statistically significant (P<0.05).
Acceleration ; Animals ; Humans ; Male ; Microscopy ; Osteogenesis* ; Rabbits ; Specimen Handling ; Tetracycline ; Tibia*

BACKGROUND: Lipoprotein (a) [Lp(a)] contains apolipoprotein(a), which is a structural homologue of plasminogen and competes with it for binding sites. It also acts by increasing plasminogen activator inhibitor-1 expression. The objective of this study was to evaluate the relationship between Lp(a) levels and restenosis rate after successful coronary stent placement. METHODS: The study included 306 patients who underwent coronary stent placement and follow-up coronary angiogram at Chonnam National University Hospital from August 1996 to June 2000. Restenosis rate was analyzed according to the level of Lp(a); Group I with high Lp(a) (n=7, Lp(a) 36 mg/dL, 58.98.8 years, female: 35.1%) and Group II with low Lp(a) (n=29, Lp(a) < 36 mg/dL, 57.79.8 years, female: 18.8%). RESULTS: 1) There was no significant differences in risk factors of atherosclerosis, clinical diagnosis, the number of involved coronary artery, left ventricular function, angiographic lesion characteristics by American College of Cardiology/American Heart Association clasification and Thrombolysis In Myocardial Infarction flow in two groups. 2) Angiographic restenosis rates were not different between two groups (group I : 33.8%, group II : 35.4%). CONCLUSION: Plasma Lp(a) levels are not related with the angiographic restenosis rate after coronary stent placement.
Apoprotein(a) ; Atherosclerosis ; Binding Sites ; Coronary Vessels ; Diagnosis ; Female ; Follow-Up Studies ; Heart ; Humans ; Jeollanam-do ; Lipoprotein(a)* ; Myocardial Infarction ; Plasma ; Plasminogen ; Plasminogen Activators ; Risk Factors ; Stents* ; Ventricular Function, Left