BACKGROUND: Abnormal hematopoietic microenvironment is an important factor causing dyshematopoiesis. However, no consensus has been reached on the sensitivity of hematopoietic stromal cells to irradiation.OBJECTIVE: To observe the changes of marrow stromal cells (MSCs) cycle and DNA content during the early stage of irradiation damage in mice, so as to further understand dyshematopoiesis due to radiation and provide scientific basis to avoid deleterious factors in hematopoietic environment.DESIGN: Completely randomized grouping and randomized controlled study based on the experimental animals.SETTING: Central laboratory of altitude military affairs medical department and altitude research institute of preventive medicine department, a military medical university of Chinese PLA.MATERIALS: This study was carried out at the Experimental Animal Center of Third Military Medical University between October 2002 and April 2003. A total of 60 healthy male Kunming mice were randomly divided into irradiation damage group and healthy control group, each having 30 mice.METHODS: The 30 mice in irradiation damage group were exposed to 60Co-γ of irradiation at a dose rate of 1.27 Gy/minutes within a distance of 4 m. Then the mice' marrow cells were harvested at day 3 and day 7 after irradiation, and were cultured in vitro for 14 days and 21 days for observation. Meanwhile the other 30 healthy mice unexposed to irradiation were considered as normal controls.MAIN OUTCOME MEASURES: Post-radiation number of MSCs colonies,cell cycle and DNA content.RESULTS: Although MSCs could grow and be adhered to walls after being exposed to irradiation of 5.0 Gy/s, the number of MSCs colonies was found significantly decreased compared to that of rnormal control group( P < 0.01 ).The colony number of the MSCs irradiated for 7 days obviously increased than that of MSCs irradiated for 3 days; however, MSCs recovered slowly and resulted in prolonged culture time, indicating the inhibited proliferation of MSCs due to irradiation damage. Results of flow cytometry showed that cells in G2+ M phase(2.60±0.41, 4.20±1.27) and DNA content (58.40±0.79,61.17 ± 1.35) in irradiation groups after 3-day and 7-day irradiation were obviously lower than those of normal control group(12.60 ±0. 75, 78.57±0. 83)(P <0.05-0.01).CONCLUSION: MSCs have relatively high sensitivity to irradiation damage and longer persisting period.

Objective:To compare the clinical outcomes between modified percutaneous kyphoplasty (PKP) and conventional PKP in the treatment of Kümmell disease.Methods:A retrospective cohort study was conducted of the 57 patients with single level kummell disease who had undergone PKP between January 2015 and December 2017 at Department of Spinal Surgery, Jiangmen Hospital Affiliated to Sun Yat-sen Uni-versity.Of them, 36 received modified PKP and 21 conventional PKP.In the modified PKP group, there were 24 males and 12 females with an age of 73.9 years±9.4 years and a course of disease of 2.2 months±1.5 months; the disease was located at a thorocic vertebra in 20 cases and at a lumbar vertebra in 16.In the conventional PKP group, there were 15 males and 6 females with an age of 72.6 years±11.9 years and a course of disease of 1.8 months±1.1 months; the disease was located at a thorocic vertebra in 10 cases and at a lumbar vertebra in 11.The 2 groups were compared in terms of operation time, bone cement volume, cement leakage, visual analogue scale (VAS), Oswestry disability index (ODI), anterior and middle heights and cobb angle of injured vertebra at postoperative 3 days, 1 and 3 months, and final follow-up.Results:There were no significant differences in the general clinical data between the 2 groups, showing compatibility between groups ( P>0.05).All the operations were accomplished uneventfully with no such serious complications as spinal cord nerve injury, wound infection, pulmonary embolism, bone cement poisoning reaction or death. There was no significant difference between the 2 groups in operation time or bone cement volume ( P>0.05).The rate of cement leakage in the modified PKP group [33.3%(9/27)] was significantly lower than that [52.4%(11/21)] in the conventional PKP group ( P<0.05).There were no significant differences be-tween the 2 groups in VAS, ODI, anterior or middle height of injured vertebra or cobb angle at postoperative 3 days or one month ( P>0.05), but the postoperative values were improved compared to the preoperative ones.At postoperative 3 months and final follow-up, the modified PKP group was significantly better in all the indexes than the conventional PKP group ( P<0.05). Conclusion:Compared with conventional PKP, the modified PKP may lead to better outcomes for Kümmell disease.