Expression of type IV collagen, metalloproteinase-2, metalloproteinase-9 and tissue inhibitor of metalloproteinase-1 in laryngeal squamous cell carcinomas.

OBJECTIVE: To investigate the significance of type IV collagen, metalloproteinase-2 (MMP-2), metalloproteinase-9 (MMP-9) and tissue inhibitor of metalloproteinase-1 (TIMP-1) expression in laryngeal squamous cell carcinomas (LSCCs). METHODS: Expression was quantified in 44 LSCC and 22 adjacent non-cancer normal tissues using a streptavidin-peroxidase conjugated immunohistochemistry and associations between the levels of the four proteins and clinicopathological characteristics in LSCC were analyzed. RESULTS: Significantly different expression of all four proteins was observed in LSCC and adjacent non-cancer normal tissues (P<0.05). Expression of type IV collagen correlated with primary cancer status (P = 0.04), clinical stage (P = 0.04) and histological grade (P = 0.01). Expression of MMP-9 correlated with the location of the tumor (P = 0.04), cervical node metastasis (P = 0.02) and prognosis (P = 0.02). The (MMP-2+MMP-9)/TIMP-1 score was associated with the prognosis of LSCC (P < 0.01). CONCLUSIONS: This study suggests that expression of type IV collagen and its regulators is strongly associated with the development of LSCC. Type IV collagen and MMP-9 may be more valuable than MMP-2 and TIMP-1 for the evaluation of clinical characteristics. Regulation of type IV collagen may contribute to the balance of MMPs and TIMPs in LSCC.

[Effects of surface potentials of tooth hard tissue on bone remodeling in rabbit tibiae].

OBJECTIVE: To investigate the influence of surface potentials of tooth hard tissue on bone remodeling. METHODS: After insured the surface potentials of human extracted teeth with electrochemical methods, teeth sections and artificial hydroxyapatite were implanted into 25 rabbits' tibiae. The rabbits were sacrificed at 1, 2, 4, 6 and 8 weeks after implantation, respectively. The bone regeneration was compared between opposite two sides (cathode side and anode side) of tooth sections using hematoxylin-eosin (HE) staining, tartrate-resistant acid phosphatase (TRAP) activity detecting and tetracycline tracing method. RESULTS: Resorption lacunae was seen in the tibiae facing to the enamel anode and new bone density in the implant bed near the cathode of tooth samples was much higher than that near the anode, while the number of TRAP positive cells near the cathode was smaller than that near the anode (P < 0.01). The fluorescent area of tetracycline tracing near the cathode was larger than that near the anode (P < 0.05). CONCLUSIONS: The cathode of tooth hard tissue (cementum) could improve or trigger new bone formation, while the other side, anode (enamel), could improve the bone resorption. This study suggests that tooth hard tissue's electrochemical characteristic might affect the remodeling of alveolar bone, and tooth supraeruption and the alveolar bone loss after tooth extraction might result from the redundant or lack of root electrochemical stimulation to bone.