[Thrombocytopoietic Efficacy of Pegylated Recombinant Human Interleukin-11 Mutein in Myelosuppressed Mice].

OBJECTIVE: To evaluate the effect of PEGylated IL-11 mutein (PEG-mIL 11) with different dose or injection frequency on thrombocytopenia in myelosuppressed mice and to compare its effect with mIL-11, so as to provide reference data for clinical use. METHODS: Myelosuppressive model with thrombocyopenia was produced in BALB/c mice by whole body 60Co γ-ray irradiation in dose of administration 2.5 Gy followed by i.p. injections of carboplatin at 50 mg/kg. In study of injection frequency, 30 thrombocytopenic BALB/c mice were randomly divided into 5 groups: vehicle control group (once daily on d1, 4, 7), mIL-11 group [200 µg/(kg·d)×9 d], PEG-mIL 11 A group [111800 µg/(kg·d)×1 d (d 1)], PEG-mIL 11 B group 900 µg/(kg·d)×2 d (d 1,5), and PEG-mIL 11 C group [600 µg/(kg·d)×3 d (d 1,4,7)]. The route of administration is subcutaneous injection. The platelet counts were monitored in the subsequant 5 weeks. In study of dose administration, 100 thrombocytopenic BALB/c mice were randomly divided into 5 groups: vehicle control group (once daily on d1 and 5), mIL-11 group 200 µg/(kg·d)×9 d, and PEG-mIL 11 low-, mid-, and high-dose groups (200, 420 and 900 µg/(kg·d)×2 d, once a day on d1 and 5). The route of administration is subcutaneous injection. The platelet counts were monitored every 2-3 days in the subsequant 5 weeks, and CFU-Meg was determined on d 8 of the bone marrow cells collection. RESULTS: After 60Co irradition and carboplatin injection, Plt level decreased with time, and a >80% reduction was noted at nadir when comparing with baseline. In frequency of administration study, the platelet nadir of the 3 PEG-mIL 11 groups were significantly higher than that of vehicle control and mIL-11 groups (P<0.05), while no significant difference was noted among the 3 groups of different administration frequences; In dose level study, the reduction of Plt count at the nadir in the 3 PEG-mIL 11 groups was significantly less than that of vehicle control and mIL-11 groups (P<0.05). And a rapid recovery of Plt count was found in the PEG-mIL 11 groups with a dose-dependent increase of Plt count on d 10. A lower reduction and a rapider recovery of RBC was also found in the PEG-mIL 11 groups. No significant effect on WBC was found for all the treatment groups. An increase in CFU-Meg was observed in PEG-mIL 11 and mIL-11 groups, with higher CFU-Meg in PEG-mIL 11 groups. CONCLUSION: A preventive effect of PEG-mIL 11 on thrombocytopenia in myelosuppressed mice has been confirmed. In comparison with mIL-11, a better effect of PEG-mIL 11 is obtained under lower dose frequency, indicating a better compliance of the treatment regimen, and providing a foundation for developing a long-acting preparation of rhIL-11.

[Influence of periodontal ligament injury on initial stability for immediately loaded mini-implant].

OBJECTIVE: To evaluate the influence of periodontal ligament (PDL) injury on initial stability for immediately loaded mini-implant anchorage. METHODS: The sample consisted of 153 adult patients with maxillary protrusion deformity. Guiding by the positioning device designed by Choi, 306 mini-implants were inserted by self-tapping in the upper right and left buccal areas between the first molars and second premolars. The mini-implants were divided into two groups according to CT scanning. The mini-implant was absolutely separated from PDL (group I), the mini-implant appeared to touch or overlay on PDL, but not contact to the adjacent roots (group II). If orthodontic force could be applied to the mini-implants for four months, the mini-implant was recorded as successful anchorage. After immediate loading for four months, the analyses were completed by SPSS 9.0 software. RESULTS: Of the 306 inserted mini-implants, 162 were absolutely separated from PDL, 136 appeared to touch or overlay on PDL, but not contact to the adjacent roots, and 8 were excluded from this study because of injury to the adjacent root. The success rates of group I and II were 87.0% and 65.4% respectively. There were significant differences in the success rates between the two groups (P<0.001). The differences between the two groups in distribution of the upper right and left area had statistical significance (P<0.05). CONCLUSION: PDL injury is one of the main reasons leading to early loosening of the mini-implant.