Effect of calcium citrate on bone integration in a rabbit femur defect model

Objective:To explore effect of calcium citrate on bone integration in a rabbit femur defect model, and to compare the bone formation with different sizes by radiological and histological study. Methods:Twenty-four male Japanese white rabbits were randomly divided into three groups (Group A.B.C)in this study.Under anesthesia,defects of four sizes(1.2,1.5,2.0 and 2.5 mm) were created in each of the rabbits.Commercially pure calcium citrate powder was placed inside the medullary compartment of the femur(Experimental),while in the contralateral femur(Control) nothing was implanted.The defects were analyzed using radiography and histological analysis by using Imagepro-Plus 6.0 software after animal was sacrificed at 4th(Group A),6th(Group B) and 8th(Group C) weeks postoperatively.Four samples were analyzed for each size of defect and each healing period.Results:The histological and the radiologic evaluation were performed after sacrification of all rabbits on postoperative 4th and 6th weeks,It showed significant difference between the experimental group and the control group when these defects were less than or equal to 2.0 mm.No statistical difference was observed when these defects were larger than 2.0 mm at all healing periods except at the 4th week.Conclusions:Calcium citrate affects the early periods of hone defects healing mechanism in Japanese white rabbits positively,especially when the defect is not too large,We suggest further studies on calcium citrate to determine the effects of various dosages,administration ways and the experimental time on the bone defects.

An integral method for calculation of capillary pressure based on centrifuge data of tight sandstone

The traditional Hassler-Brunner(HB)interpretation method of centrifuge capillary pressure is widely used in materials,soil,biotechnology,and especially in the petroleum industry.However,the assumptions of the traditional method cannot be simultaneously satisfied,the traditional method has been known to lead significant errors in some cases.In this paper,a new double integral method is proposed to evaluate the centrifuge capillary pressure of long tight sandstone samples.Both the changes of capillary length and interface of wetting phase and non-wetting phase fluids are considered by the new integral method,thus the average pressure and saturation derived from the proposed double integral method is more sufficient in theoretic foundation and clearer on physical meaning.By comparing with the measured capillary pressure of long tight sandstone core samples from porous plate,the capillary pressure calculated from traditional HB method is obviously smaller than the measured value,and the discrepancy increases with the decreasing core porosity.However,the average capillary pressure obtained by the proposed double integral method is remarkably consistent with the measured value.The findings of this study can help for better understanding of distribution of wetting phase fluid and average centrifuge capillary pressure in the core during centrifugal process.