ABSTRACT
Objective To study distributions of the compressive strength on the whole spine endplates by measuring the compressive strength at different locations of the whole spine endplates. Methods Indentation tests were performed at 49 locations in 225 bony endplates of intact human vertebrae (C3 S1) from 5 fresh male specimens to record the failure loads. Results (1) For the whole spine endplates, failure loads of the cervical and lumbar spine were found to be higher than those of the thoracic spine (P<0.01).The failure load was first decreased from C3 to C7 before increasing to T1, and then dropping through T7 and rising again from T8, reaching the maximum at L4, and dropping at L5 before increasing again at S1. (2) The failure load at inferior cervical endplates was significantly higher than that at superior endplates except at C5 and T1 (P＜0.05). (3) Within the intervertebral space, the cranial endplates had a higher yield stress than the caudal endplates except at C5/6, T12/L1 and L5/S1. (4) Failure loads were generally increased from the central to peripheral zones (P＜0.05). (5) For different angular points, failure load distributions were found among the endplates (P<0.01). (6) Distributions of the compressive strength on the endplates varied significantly within the whole spine（P<0.01）. It was found that at C3/4, the failure load at posterior was higher than that at anterior, but at C5/6, the failure load at posterior and anterior was balanced. At T1, the failure load was found to be higher at posterior again, until passing through T2 5, and at T6 L3, the failure load at anterior was higher than that at posterior, and balanced between the anterior and posterior again at L4. At L5 S1, the failure load at posterior was higher than that at anterior. Conclusions The strength distributions on the endplates varied significantly at different locations within the whole spine, which was closely correlated with the physiological curve of the spine. The failure load at inferior endplates was higher than that at superior endplates and it was increased from central to peripheral zones. Within the intervertebral space, the compressive strength at cranial endplates was higher than that at caudal endplates.
ABSTRACT
@#ObjectiveTo study the characteristic of apoptosis and the expression of interleukin-1β(IL-1β)and caspase-3, as well as the relation among them after spinal cord injury(SCI) in rats.MethodsAdult SD rats were divided into two groups randomly: sham group and spinal cord injury group. The rats were killed at 1 h, 8 h, 24 h, and 72h after surgery. The expression of IL-1β and caspase-3 was determined with immunohistochemistry and the apoptosis was labeled by TUNEL.ResultsThere was only a few cells that expressed low level IL-1β and caspase-3 in sham group, but they both enhanced in SCI group within 8 h after operation, and then decreased to the level similar to sham group 72 h after operation. The rates of TUNEL-positive cells were similar with that of IL-1β and caspase-3 after SCI. There was positive correlation among expression of IL-1β and caspase-3 and apoptosis index.ConclusionExpression of IL-1β and caspase-3 increase and a large number of TUNEL-positive cells present after SCI in rats, and there is positive correlation among them.