Objective To study the general shape of anterior cruciate ligament (ACL) insertion in rabbits and establish an animal model of ACL reconstruction using oval tunnels.Methods Eighteen mature white New Zealand rabbits were used in this study.Eight of them were used for anatomy study and the other 10 were for building an animal model.After removal of the medial femoral condyle and other soft tissues around ACL,the morphology of the ACL insertion was examined and the diameter of ACL insertions was measured using a caliper.An oval-tunnel dilator (1.6 mm×2.5 mm) was designed to make an oval-tunnel in the right knee of the rabbits while a round tunnel was drilled using a 2 mm diameter Kirschner wire in the left knee of the rabbits.Their hamstring tendon grafts were harvested as grafts for both sides and the compatibility between the bone tunnel and graft was examined for both groups.Right after the surgery,the knees of both sides were given the three-dimensional CT scan.Results The shape of ACL insertion of rabbits was oval.In the femur side,the average major and minor diameter of the ACL insertion was 5.28 ± 0.83 mm and 2.61 ± 0.33 mm respectively.In the tibial side,the major and the minor diameter of the ACL insertion was 5.33 ± 0.40 mm and 2.68 ±0.11 mm.The bone tunnel was compatible with the graft in both groups.In the oval tunnel ACL reconstruction group,the cross sectional area of the femoral bone tunnel was 3.18 ± 0.09 mm2 and the cross sectional area of the tibial bone tunnel was 3.26 ± 0.15 mm2.In the round tunnel ACL reconstruction group,the corresponding measurements were 3.13 ± 0.10 mm2 and 3.11 ± 0.11 mm2 respectively.There was no significant difference between the two groups.Conclusion The shape of ACL insertion in rabbits is oval.Using the self-made oval tunnel dilator we have successfully built an oval tunnel ACL reconstruction animal model with a good compatibility between the bone tunnel and graft.This lays the foundation for further research in the future.

Objective To explore the influence of elevating the oxygen pressure on articular chondrocytes in vitro.Method A hydrogen peroxide induced human articular chondrocyte damage model was established.Then the articular chondrocyte viability was detected using the CCK-8 kit.Collagen Ⅱ(COL Ⅱ),The expression levels of aggrecan (ACAN),matrix metalloproteinase 13 (MMP13) and adisintegrin and metalloproteinase with thrombospondin motifs 5 (ADAMTS5) were detected using the realtime PCR and Western blotting.Result The viability of articular chondrocytes improved at 12 h but decreased at 24 h after the stimulation of hydrogen peroxide.Twenty-four hours later,the average expression level of COL Ⅱ and ACAN decreased(P＜0.05),while that of MMP13 and ADAMTS5 elevated(P＞0.05).Conclusion Hydrogen peroxide induced elevation of the extracellular oxygen pressure can influence the synthesis and degradation of the articular chondrocyte extracellular matrix.

Objective To evaluate the effect of sevoflurane anesthesia on the expression of phosphorylated cAMP response element-binding protein (p-CREB) in the hippocampal neurons of developing rats.Methods Thirty-two healthy male Sprague-Dawley rats, aged 7 days, weighing 10-15 g, were equally and randomly divided into either control group (group C) or sevoflurane anesthesia group (group Sev) using a random number table.Group C inhaled 30％ oxygen for 6 h.Group Sev inhaled 3％ sevoflurane for 6 h.Eight rats in each group were sacrificed immediately after the end of oxygen or sevoflurane inhalation, and the hippocampus was removed for determination of the expression of p-CREB.The rats at ages 2 months underwent Morris water maze test.The rats were then sacrificed, and the hippocampus was removed for determination of the expression of p-CREB by Western blot.Results Compared with group C, the escape latency and swimming distance were significantly prolonged, the frequency of crossing the original platform was decreased, the percentage of the time of staying at the quadrant Ⅱ was decreased, and the expression of p-CREB in hippocampal neurons was down-regulated in group Sev.Conclusion The mechanism of sevoflurane anesthesia-induced neurotoxicity is related to inhibition of p-CREB expression in hippocampal neurons of developing rats.

Objective To evaluate the changes in the expression of CC-chemokine ligand 3 (CCL3) and CC-chemokine receptor 5 (CCR5) in the spinal cord during hyperalgesia induced by remifentanil in rats with incisional pain.Methods Thirty-two male Sprague-Dawley rats,aged 2-3 months,weighing 240-260 g,were randomly divided into 4 groups (n=8 each) using a random number table:control group (group C),incisional pain group (group Ⅰ),remifentanil group (group R) and remifentanil+incisional pain group (group R+I).A 1-cm longitudinal incision was made in the plantar surface of the left hindpaw in anesthetized rats.While the model of incisional pain was established,remifentanil was infused for 60 min at 1 μg · kg-1 · min-1.At 24 h before infusion of remifentanil (baseline) and 2,6,24 and 48 h after the end of infusion,the mechanical paw withdrawal threshold (MWT) and thermal paw withdrawal latency (TWL) were measured.The rats were sacrificed after the last measurement of pain threshold,the lumbar segment (L4-6) of the spinal cord was removed for determination of CL3 and CCR5 mRNA expression (by real-time PCR) and CL3 and CCR5 expression (by Western blot).Results Compared with group C,the MWT was significantly decreased,the TWL was shortened,and the expression of CCL3 and CCR5 mRNA and protein was up-regulated in I,R and R+ I groups.Compared with I and R groups,the MWT was significantly dccreascd,the TWL was shortened,and the expression of CCL3 and CCR5 mRNA and protein was up-regulated in group R+I.Conclusion The mechanism by which remifentanil induces hyperalgesia is related to up-regulated expression of CCL3 and CCR5 in the spinal cord of rats with incisional pain.

Objective To evaluate the effects of hydrogen on apoptosis in hippocampal neurons caused by sevoflurane anesthesia in neonatal rats.Methods Forty-eight healthy male Sprague-Dawley rats,aged 7 days,weighing 12-20 g,were randomly divided into 3 groups (n=16 each) using a random number table:control group (group C);sevoflurane anesthesia group (group S);hydrogen group (group H).In C and S groups,the rats inhaled 30％ oxygen and 3％ sevoflurane for 6 h,respectively.In group H,3％ sevoflurane and 2％ hydrogen were inhaled for 6 h.Eight rats in each group were randomly selected and sacrificed at 7 days after birth (after the end of oxygen,sevoflurane or hydrogen inhalation),and the hippocampus was removed for determination of the expression of activated caspase-3 and myelin basic protein by Western blot.At 28 days after birth,8 rats were selected,and Y-maze and Morris water maze tests were performed to evaluate the cognitive function.The total number of entries into each arm,the number of spontaneous alternation,escape latency and time of staying at the platform quadrant were recorded.Results Compared with group C,the percentage of spontaneous alternation was significantly decreased,the escape latency was prolonged,and the time of staying at the platform quadrant was shortened,and the expression of activated caspase-3 was significantly up-regulated,and the expression of myelin basic protein was down-regulated in group S.Compared with group S,the percentage of spontaneous alternation was significantly increased,the escape latency was shorten,and the time of staying at the platform quadrant was prolonged,and the expression of activated caspase-3 was significantly downregulated,and the expression of myelin basic protein was up-regulated in group H.There was no significant difference in the number of entries into each arm in Y-maze test between the three groups.Conclusion Hydrogen can inhibit apoptosis in hippocampal neurons caused by sevoflurane anesthesia in neonatal rats.

Objective To evaluate the changes in the expression of protein interacting with Cα kinase 1 (PICK1) in the spinal cord and dorsal root ganglion (DRG) neurons during remifentanil-induced hyperalgesia in rats with incisional pain.Methods Thirty-two male Sprague-Dawley rats, weighing 240-260 g, aged 42-49 days, were randomly divided into 4 groups (n =8 each) using a random number table: control group (group C) , incisional pain group (group Ⅰ) , remifentanil group (group R), and remifentanil + incisional pain group (group R + Ⅰ).In R and R+Ⅰ groups, remifentanil was infused intravenously for 60 min at the rate of 1.2 p,g · kg-1 · min-1.In C and Ⅰ groups, normal saline was infused intravenously for 60 min at the rate of 0.12 ml · kg-1 · min-1.In Ⅰ and R+Ⅰ groups, the model of incisional pain was established, and remifentanil and normal saline were infused intravenously, respectively, at the same time.The mechanical paw withdrawal threshold (MWT) and thermal paw withdrawal latency (TWL) were measured before normal saline or remifentanil infusion, and at 2, 6, 24, and 48 h after the end of normal saline or remifentanil infusion (T1-4).The rats were sacrificed after the last measurement of pain threshold.The lumbar segment (L4-6) of the spinal cord and left DRGs were removed for determination of the expression of PICKl mRNA (by quantitative real-time reverse transcriptase-polymerase chain reaction) and PICK1 protein (by Western blot).Results Compared with group C, the MWT was significantly decreased, the TWL was shortened, and the expression of PICK1 protein and mRNA was up-regulated in R and R+Ⅰ groups, and the MWT was significantly decreased, the TWL was shortened (P＜0.05) , and no significant change was found in the expression of PICK1 protein and mRNA in group Ⅰ (P＞0.05).Compared with group Ⅰ, the MWT was significantly decreased, the TWL was shortened, and the expression of PICK1 protein and mRNA was up-regulated in group R+Ⅰ (P＜0.05).Compared with group R, the MWT was significantly decreased, the TWL was shortened (P＜0.05) , and no significant change was found in the expression of PICK1 protein and mRNA in group R+ Ⅰ (P＞0.05).Conclusion The mechanism by which remifentanil induces hyperalgesia may be related to up-regulation of PICK1 expression in the spinal cord and DRG neurons of rats with incisional pain.

OBJECTIVETo investigate the effect of rupture and reconstruction of the anterior cruciate ligament (ACL) on the degeneration of rabbit knee articular cartilage.

METHODS14 mature New Zealand white rabbits were divided into four groups. In group I, the ACL of the right knees in 7 rabbits was resected and immediately reconstructed, and the contralateral ACL was resected only in controll f group I. In group II, the ACL of the right knees in 7 rabbits was reconstructed 3 weeks after the ACL was resected and the contralateral joints in control group II, in which only a medial arthrotomy was performed. The rabbits were killed 8 weeks after the operation. The methods of ink straining, histology and SEM were used to analyze the changes in articular cartilage of the joints.

RESULTSThe results of ink method and HE straining were analyzed quantitatively. The degeneration of knee articular cartilage in group I was significantly weaker than that in control group I (Hc = 5.9889, P = 0.0144). The degeneration of knee articular cartilage in group II was as serious as that in control group I (Hc = 0.7143, P = 0.785).

CONCLUSIONSImmediate reconstruction of the ACL can effectively prevent articular cartilage from degeneration. Once the articular cartilage damaged moderately, delayed reconstruction of the ACL could not effectively reduce the development of degeneration. So once the ACL is ruptured, reconstruction should be performed in the early stage to restore the stability of knee joint to prevent the articular cartilage from degeneration.

Animals ; Anterior Cruciate Ligament Injuries ; Cartilage, Articular ; pathology ; Disease Models, Animal ; Knee Joint ; physiopathology ; Rabbits