太子参对心肌梗死后慢性心衰大鼠心功能与基质金属蛋白酶表达的影响

目的：研究太子参对心肌梗死诱导的慢性心衰大鼠心功能与基质金属蛋白酶（MMPs）表达和活性的作用。方法:采用结扎大鼠冠状动脉复制急性心肌梗死诱导慢性心衰动物模型，以血流动力学指标分析心功能，RT-PCR分析MMP-2与MMP-9的mRNA表达，酶谱法分析MMP-2与MMP-9的活力。结果:大鼠冠脉结扎6周后，心功能显著紊乱；左心室组织MMP-2与MMP-9 mRNA水平显著提高、酶活力增加。太子参水煎液连续灌胃给药5周，可显著改善心衰大鼠的血流动力学，抑制左心室组织MMP-2与MMP-9的活力和mRNA的水平增加（与模型组比较，差异显著，P<0.01，P<0.05）。结论:大鼠冠脉结扎6周形成慢性心衰模型，太子参水煎液可改善大鼠冠脉结扎所诱导的心衰，其机制可能与MMPs的表达和活性有关。     

Regulation of MMP-9 (92 kDa type IV collagenase/gelatinase B) expression in stromal cells of human giant cell tumor of bone

Matrix metalloproteinases (MMPs) play an important regulatory role in tissue morphogenesis, cell differentiation, tumor invasion and metastasis. Several authors have reported a direct correlation between the production of 72 kDa (MMP-2) and 92 kDa (MMP-9) type IV collagenases/gelatinases and the metastatic potential of cancer cells. Recently, we have identified the expression of both MMP-2 and MMP-9 in primary cultures of human giant cell tumor (GCT) of bone in vitro, and in tissue extracts in vivo. Interestingly, MMP-9 is not secreted by late-passaged GCT cells. It is possible that the production of MMP-9 is regulated by certain factor(s) secreted by the multinucleated giant cells in the primary culture. In order to test this hypothesis, the effect of primary-culture-conditioned medium on the expression of MMP-9 by late-passaged mononuclear stromal cells was examined. Adding conditioned medium from the primary GCT culture to the late-passaged stromal cells induced MMP-9, as evidenced by the presence of lytic bands at Mr 92000 and 72000 on a gelatin zymogram. These enzyme activities were inhibited by EDTA, a well-known inhibitor of the MMPs. We confirmed these results by Western blotting using specific antibodies and RT-PCR for MMP-2 and MMP-9. Immunofluorescence studies with specific antibodies to MMP-9 further confirmed its expression by the passaged stromal cells cultured in the primary-culture-conditioned medium. The data indicate that MMP-2 and MMP-9 are produced by the mononuclear stromal cells when cultured in GCT primary-culture-conditioned medium. This suggests that multinucleated giant cells in primary cultures secrete a factor(s) that stimulates stromal cells to produce MMP-9, which, in turn, may contribute to the aggressive behavior of GCT.     

Gelatinase-B (Matrix Metalloproteinase-9; MMP-9) secretion is involved in the migratory phase of human and murine muscle cell cultures

The remodelling of connective tissue components is a fundamental requirement for a number of pivotal processes in cell biology. These may include myoblast migration and fusion during development and regeneration. In other systems, similar biological processes are facilitated by secretion of the matrix metalloproteinases (MMPs), especially the gelatinases. This study investigated the activity of the gelatinases MMP-2 and 9 by zymography on cell conditioned media in cultures of cells derived from explants of the human masseter muscle and in the murine myoblast cell-line C2C12. Expression of MMP-9 by western blotting and TIMP-1, the major inhibitor of MMPs, by northern blotting, during all phases of myoblast proliferation, migration, alignment and fusion, was also measured. Irrespective of the origin of the cultures, MMP-9 activity was secreted only by single cell and pre-fusion cultures whilst MMP-2 activity was secreted at all stages as well as by myotubes. The loss of MMP-9 activity was due to the loss of MMP-9 protein expression. TIMP-1 mRNA was not detectable at the single cell stage but its expression increased as cells progressed through the pre-fusion and post-fusion stages to reach a maximal in myotube containing cultures. Migration of cells derived from human masseter muscle was inhibited, using a specific anti-MMP-9 blocking monoclonal antibody (6-6B). These data are consistent with the concept that regulation of matrix turnover via MMP-9 may be involved in the events leading to myotube formation, including migration. Loss of expression of this enzyme and expression of TIMP-1 mRNA is associated with myotube containing cultures. Consequently, the ratio between MMPs and TIMPs maybe important in determining myoblast migration and differentiation.     

Creep in a palladium-enriched high-copper amalgam

Palladium additions to a dispersed phase high-copper amalgam have been shown recently to suppress markedly the eta' (Cu6Sn5) concentration and decrease creep. A detailed study of the dental and 24 h creep for Pd containing high-copper amalgams and six commercial controls as a function of applied temperature and stress was performed. One part of Ag-Cu or Ag-Cu-Pd dispersants with substitutions of up to 20wt/o Pd for either Ag or Cu was blended with two parts of traditional amalgam alloy. Various temperatures from 25 to 60 degrees C and stresses from 36 to 72 MPa were applied to the samples during the test. For commercial controls and experimental amalgams with no Pd, creep is a strong function of temperature and stress. The experimental amalgam containing up to 10wt/o Pd, Pd substituted for Ag, demonstrated essentially constant creep over the temperature and stress range applied.     

Corrosion of the eta'(Cu-Sn) phase in dental amalgam

Previous studies have shown preferential corrosion of the eta'(Cu-Sn) phase in high-copper dental amalgam both in vitro and in vivo, while samples of pure eta' have shown high corrosion resistance. To clarify this contradiction, samples of pure eta' crystals mixed with other phases were prepared and tested. Evaluation of the corrosion resistance was based on the results of coulometry at constant potential and potentiodynamic polarization. The corrosion susceptibility of eta' in the matrix of gamma 1(Ag-Hg) was considerably higher than the susceptibility of isolated eta'. The susceptibility of pure eta' also could be increased by plating it will small amounts of Hg. It was concluded that in dental amalgam, the presence of mercury in the phases surrounding eta' reduces its resistance to corrosion. Although eta' is more resistant to corrosion than gamma 2(Sn-Hg) which appears in low-copper amalgams, it is the least corrosion resistant major phase in high-copper amalgams and can suffer deterioration.     

Matrix Metalloproteinases and Inflammatory Cytokines in Oral Fluid of Patients with Chronic Generalized Periodontitis and Various Construction Materials

We present the results of comparative enzyme-linked immunosorbent assay of matrix metalloproteinases MMP-2, MMP-8, MMP-9; IL-1β and IL-6; tissue inhibitors of MMP (TIMP-1, TIMP-2), and TNF-α. The object of study was oral fluid of practically healthy subjects with intact periodontium and patients with chronic generalized periodontitis with various structural materials of dental restorations. It was found that MMP-9 in oral fluid could be considered as a marker of chronic generalized periodontitis irrespective of the presence or absence of metal dental restorations. The level of MMP-8 surpassed the normal only in oral fluid of patients with chronic generalized periodontitis with metal restorations. The correlations between the studied parameters in patients attest to relatively similar regulation of MMP, IL and TIMP secretion in oral fluid in practically healthy subjects with intact periodontium. In patients with inflammatory destructive periodontal diseases with and without metal dental restorations, the correlation coefficients indicate initiation of biochemical cascade accompanied by activation of cytokine production in response to etiological factors. Patients with periodontitis and metal orthodontic structures showed more pronounced reaction. Orthodontic structures made from chromium-cobalt, or chromium-nickel alloys in the oral cavity of these patients increased the levels of MMP-2, IL-1β and IL-6 in oral fluid.     

Thrombin and TNF-alpha/IL-1beta synergistically induce fibroblast-mediated collagen gel degradation

Degradation of preexisting and newly synthesized extracellular matrix is thought to play an important role in tissue remodeling. The current study evaluated whether thrombin and TNF-alpha/IL-1beta could collaboratively induce collagen degradation by human fetal lung fibroblasts (HFL-1) and adult bronchial fibroblasts cultured in three-dimensional collagen gels. TNF-alpha/IL-1beta alone induced production of matrix metalloproteinases (MMPs)-1, -3, and -9, which were released in latent form. With the addition of thrombin, the latent MMPs were converted into active forms and this resulted in collagen gel degradation. Part of the activation of MMPs by thrombin resulted from direct activation of MMP-1, MMP-2, MMP-3, and MMP-9 in the absence of cells. In addition, tissue inhibitor of metalloproteinase-1 production was inhibited by the combination of thrombin and TNF-alpha/IL-1beta. These results suggest that thrombin and TNF-alpha/IL-1beta synergize to induce degradation of three-dimensional collagen gels through increasing the production and activation of MMPs, and that this effect is mediated through both direct activation of MMPs by thrombin and indirectly by thrombin activation of fibroblasts. Through such mechanisms, thrombin could contribute to many chronic lung disorders characterized by tissue remodeling.     

Gelatinolytic activity of matrix metalloproteinase in tumor tissues correlates with the invasiveness of oral cancer

We examined whether or not the gelatinolytic activity in tumor tissue was associated with the invasion and metastasis of oral squamous cell carcinoma (OSCC). Tissue homogenates were prepared from 57 biopsy specimens of OSCC. The gelatinolytic activities in the homogenates were measured by gelatin zymography and its densitometric analysis. The Immunoblot findings revealed the major gelatinolytic activities to be due to matrix metalloproteinase (MMP)-2 and -9. The zymography-detected gelatinolytic activities of MMP-2 and MMP-9 in the tissue specimens significantly correlated with the degree of immunohistochemical staining detected in frozen sections of the same biopsy specimens. According to a histopathological analysis of the mode of invasion, highly invasive cases showed the increased gelatinolytic activities of MMP-2 as well as MMP-9 in the tissue specimens. Although no significant differences were observed in the gelatinase activities between the metastatic cases and the non-metastatic cases, the levels of tissue inhibitor of MMP (TIMP)-1 in the tumor tissue specimens were higher in the non-metastatic cases than in the metastatic cases. The cases with the high levels of MMPs and low levels of TIMP-1 thus seemed to have a high potential to metastasize. As a result, the zymographic measurement of the gelatinolytic activity in biopsy tissue specimens may therefore be useful in predicting the behavior and prognosis of OSCC.     

Inhibition of the activities of matrix metalloproteinases 2, 8, and 9 by chlorhexidine

Matrix metalloproteinases (MMPs) are a host cell-derived proteolytic enzyme family which plays a major role in tissue-destructive inflammatory diseases such as periodontitis. The aim of the present study was to evaluate the inhibitory effect of chlorhexidine (CHX) on MMP-2 (gelatinase A), MMP-9 (gelatinase B), and MMP-8 (collagenase 2) activity. Heat-denatured type I collagen (gelatin) was incubated with pure human MMP-2 or -9 activated with p-aminophenylmercuric acetate (APMA), and the proteolytic degradation of gelatin was monitored by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Coomassie blue staining. The effect of CHX on MMP-8 activity was also studied with a cellular model addressing the ability of phorbol myristate acetate (PMA)-triggered human peripheral blood neutrophils (polymorphonuclear leukocytes [PMNs]) to degrade native type I collagen. CHX inhibited the activities of both gelatinases (A and B), but MMP-2 appeared to be more sensitive than MMP-9. Adding calcium chloride to the assay mixtures almost completely prevented the inhibition of MMP-9 activity by CHX, while the inhibition of MMP-2 activity could be reversed only when CHX was used at a low concentration. This observation suggests that CHX may act via a cation-chelating mechanism. CHX dose-dependently inhibited collagenolytic activity of MMP-8 released by PMA-triggered PMNs. MMP-8 without APMA activation was inhibited clearly more efficiently than APMA-activated MMP-8. Our study suggests that the direct inhibition of the MMPs' activities by CHX may represent a new valuable effect of this antimicrobial agent and explains, at least in part, the beneficial effects of CHX in the treatment of periodontitis.     

Soluble EMMPRIN (extra-cellular matrix metalloproteinase inducer) stimulates the migration of HEp-2 human laryngeal carcinoma cells, accompanied by increased MMP-2 production in fibroblasts

The basement membrane functions as a barrier against the invasion of cancer cells. It is therefore important to investigate the mechanism of basement membrane degradation by matrix metalloproteinases (MMPs). Previously, cancer cells were long considered to be the major source of MMPs; however, current evidence indicates that most MMPs in cancer tissue are produced by stromal rather than cancer cells. A glycoprotein highly expressed on the cancer-cell membrane, EMMPRIN (extra-cellular matrix metalloproteinase inducer), exhibits the potential role of the MMP inductor in stromal cells. Depending on the cell type, EMMPRIN can stimulate the production of MMP-1, MMP-2, and MMP-3. We here report that soluble full-length EMMPRIN is liberated from HEp-2 human laryngeal epidermoid carcinoma cells, probably via microvesicle shedding. Soluble EMMPRIN stimulates human fibroblasts to produce MMP-2, after which the augmented migration of HEp-2 cells occurs, as observed in an invasion chamber assay with separately cultured fibroblasts. An anti-EMMPRIN function-blocking antibody reduced MMP-2 activity in the conditioned medium and inhibited the migration of HEp-2; obviously, EMMPRIN activity contributes to cancer-cell migration. We postulate that soluble EMMPRIN probably triggers the promotion of cancer invasion in vivo.     

不同转移潜能的人肿瘤细胞系金属蛋白酶活性分析

目的探讨不同转移潜能的人类肿瘤细胞的金属蛋白酶（ＭＭＰｓ）活性与其侵袭转移潜能的相关性。方法分别选取具有不同转移潜能的人类肺癌细胞系（ＰＧ、ＰＡａ、ＢＥ１、ＣＬ３、ＬＨ７）、黑色素瘤细胞系（ＷＭ３５、ＷＭ１３４１ｂ、ＷＭ９８３ａ、ＷＭ４５１）及前列腺癌细胞系（ＰＣ，ＰＣ３Ｍ），经细胞培养，条件培养基的收集与浓缩，利用明胶Ｚｙｍｏｇｒａｐｈｙ法检测以上各组细胞ＭＭＰ２和ＭＭＰ９的产生及活性差异，并将这种差异与各自的转移潜能联系起来。结果转移能力相对较高的细胞系产生ＭＭＰｓ的能力相应强于转移能力相对较低者：ＰＧ高于ＰＡａ，ＢＥＩ高于ＣＬ３和ＬＨ７。在进展期黑色素瘤株ＷＭ９８３ａ和转移瘤株ＷＭ４５１出现了ＭＭＰ９的表达，早期瘤株则无。前列腺瘤细胞ＰＣ３的转移性克隆ＰＣ３Ｍ的条件培养基中有较高的ＭＭＰ９活性。结论肿瘤细胞的侵袭转移潜能与其产生ＭＭＰｓ的能力密切相关。     

Metal release from dental biomaterials

Levels of corrosion products released from dental alloys in natural or synthetic saliva, i.e. from amalgams, cobalt, gold, nickel, iron, or titanium based alloys have been surveyed. The amounts of Ag, Au, Cd, Co, Cr, Cu, Hg, Mo, Ti or Ni released from such alloys, either in vitro or in vivo during animal tests or during clinical usage have been compiled. The quantities released have been adapted to a 'standard restored man' with a specified number of restorations or a specified construction with a defined surface area, and compared to man's food and drink intake of similar elements. This was done as one approach to a security analysis of wearing dental alloys. In view of the assessment of extensive corrosion testing using electrochemical methods, rather scarce information seems presently available pertinent to release kinetics of specific elements in various biological environments like saliva or saliva substitutes. Several examinations indicate that mercury released from amalgams could be a substantial part of man's daily intake of this element, e.g. in the initial period following insertion, as well as on a long-term basis. From a copper amalgam cadmium could be released in vitro in amounts close to food and drink intake. The mercury release from the amalgam surface seems to be strongly influenced by the interaction of mechanical forces, e.g. chewing, and seems to be released according to a cyclic pattern. From a base metal alloy with high nickel content nickel could be released in vitro at the same level as from food and drink intake. However, from cobalt based alloys the nickel release seems insignificant in this context. The elemental release from the other alloys seemed to be far below the intake of similar elements from food and drink. Release under static and dynamic conditions has been discussed.     

MRL/lpr狼疮小鼠肾脏明胶酶表达随增龄变化及意义

目的 观察不同周龄MBL/lpr狼疮小鼠肾脏明胶酶的表达及其随增龄而发生的活性变化及意义。方法 取8、16与24周龄RMRL/lpr狼疮小鼠的肾组织进行常规病理检测。利用含有放射自显影的成像乳胶对冷冻肾组织切片进行原位明胶酶活性的检测;利用免疫组织化学检测肾脏明胶酶A与明胶酶B的酶B的蛋白表达变化,十二氨基磺酸钠-聚丙烯酰胺凝胶电泳（SDS-PACE）明胶酶谱法检测肾脏明胶酶A、B的活性变化。结果 8周龄狼疮小鼠肾组织吵仅在血管处检测到明胶酶的活性;16与24周龄狼疮小鼠肾小球内明胶酶的净活性明显增加。在肾小球以及肾小管间质上也可检测到明胶酶的活性,乙二胺四乙酸（EDTA）能够抑制肾脏明胶酶的活性,免疫组织化学与SDS-PAGE明胶酶谱法结果显示其肾组织中明胶酶A与明胶酶B的蛋白质表达及活性均明显增加。结论 明胶酶A、B在自发性狼疮小鼠肾炎中的表达及活化随增龄均明显增加,活化态的明胶酶可能在狼疮性肾炎细胞外基质重塑中发挥重要的作用。     

Matrix metalloproteinase (MMP)-2 and MMP-9 activities in human seminal plasma.

We report on the existence of two kinds of matrix metalloproteinases (MMPs), MMP-2 and MMP-9, in human seminal plasma. Partial purification of the proteinases was achieved by two steps, consisting of chromatography on a gel-filtration column and then on a gelatin affinity column. Proteinase activities in the chromatography extracts were shown to hydrolyse a fluorescent substrate specific to MMPs (Dnp-Pro-Leu-Gly-Leu-Trp-Ala-D-Arg-NH2). The proteinases were detected using gelatin-zymography, but were not detected using casein-zymography, and were also inhibited by EDTA, EGTA and o-phenanthroline. Molecular weights of the proteinases were determined by SDS-PAGE, gelatin-zymography and Western blot to be approximately 92, 84, 72, 67, 52 and 45 kDa. Gelatin-zymography showed three major bands of activity at 72, 67 and 52 kDa and minor bands at 92, 84 and 45 kDa. Apart from the two smallest bands, these proteinases were all recognized by the polyclonal antibodies for MMP-2 or MMP-9. These results indicate that two kinds of pro-form and active-form matrix metalloproteinases, MMP-2 and MMP-9, and their degradation products, are present in human seminal plasma.     

Calprotectin inhibits matrix metalloproteinases by sequestration of zinc.

BACKGROUND/AIMS: Calprotectin, a 36 kDa protein present in neutrophil cytoplasm, has antimicrobial and apoptosis inducing activities, which are reversed by the addition of zinc. Matrix metalloproteinases (MMPs), a family of zinc dependent enzymes, are important in many normal biological processes including embryonic development, angiogenesis, and wound healing, but also pathological processes such as inflammation, cancer, and tissue destruction. The aim of this study was to investigate whether calprotectin can inhibit MMP activity, and whether such inhibition could be overcome by the addition of zinc. METHODS: MMP activity was measured by the degradation of substrates precoated on to microwells, and visualised by Coomassie blue staining of residual substrate. Seven metalloproteinases (MMP-1, MMP-2, MMP-3, MMP-7, MMP-8, MMP-9, and MMP-13) were tested against two substrates: gelatin and alpha-casein. RESULTS: All MMPs except MMP-1 were active against gelatin, whereas MMP-7 was the only enzyme active against alpha-casein. The addition of calprotectin inhibited the activity of all the MMPs, but different concentrations of the protein, from 0.3 microM to > 11microM, were necessary to produce a 50% inhibition of the MMPs. Inhibition by calprotectin was largely overcome by the addition of zinc. CONCLUSIONS: The findings suggest that calprotectin inhibits MMPs by sequestration of zinc. The data also suggest that MMPs have different affinities for zinc and that calprotectin has a lower zinc affinity than the MMPs.     

Increased expression of matrix metalloproteinase-2, matrix metalloproteinase-9 and matrix metalloproteinase-13 in lesional skin of bullous pemphigoid

BACKGROUND: Matrix metalloproteinase (MMP)-2, MMP-9 and MMP-13 can degrade type IV collagen which is the major component of the basement membrane zone (BMZ). In bullous pemphigoid (BP), the separation occurs within the BMZ. OBJECTIVE: To evaluate the involvement of MMPs in the pathogenesis of BP, we examined the expression of MMP-2, MMP-9 and MMP-13 in the lesional skin of BP patients. METHODS: The expression of MMP-2, MMP-9, MMP-13, tissue inhibitors of metalloproteinase (TIMP)-1 and TIMP-2 was analyzed by immunohistochemistry in the lesional skin of BP patients in comparison with that in normal human skin. Next, the cellular sources of MMP-2, MMP-9 and MMP-13 were analyzed by double immunohistochemistry. Finally, the levels of these MMPs in the serum and blister fluid of BP patients were measured by ELISA. RESULTS: The number of cells expressing MMP-2, MMP-9 and MMP-13 were significantly increased in the lesional skin of BP patients as compared to that in normal skin. Although the number of cells expressing TIMP-1 and TIMP-2 were also increased in the lesional skin of BP patients as compared to that in normal skin, the ratio of MMPs to TIMPs in the lesional skin of BP patients was high (2.4:1). T cells comprised the major source of MMP-2, MMP-9 and MMP-13, while a proportion of mast cells and eosinophils also expressed these MMPs. Furthermore, marked expression of MMP-2 was detected in the epidermal keratinocytes. The levels of these MMPs in the blister fluid were significantly greater than those in the serum. CONCLUSION: These results suggest that MMP-2, MMP-9 and MMP-13 may be involved in the mechanism of blister formation in BP and that besides infiltrating inflammatory cells, structural cells like epidermal keratinocytes may also participate in the induction of blister formation in BP.     

Implication of extracellular matrix metalloproteinases in the course of chronic inflammatory airway diseases

Matrix metalloproteinases (MMPs) are major proteolytic enzymes that are involved in extracellular matrix (ECM) turn over. MMP-2 (gelatinase A) and MMP-9 (gelatinase B) cleave type IV collagen, which is an important constituent of basement membrane. These enzymes play an important role in normal tissue homeostasis, but imbalance between MMPs and their tissue inhibitors (TIMPs) is thought to be a critical factor in regulating tissue remodeling. MMP-2 is produced by fibroblasts, endothelial, and epithelial cells, while MMP-9 is mainly produced by inflammatory cells. The role of MMPs was investigated through biochemical analysis or in situ expression, in the pathogenesis of two chronic inflammatory airway diseases, asthma and nasal polyposis. Both are characterized with the accumulation of active inflammatory cells, matrix remodeling and epithelial changes. Increased levels of MMP-9 and TIMP-1 were found in asthmatic subjects and NP. In NP, MMP-9 expression was detected in epithelial, endothelial and inflammatory cells. In this setting, MMP-9 could play a crucial role in the transmigration of basement membrane components by inflammatory cells leading to inflammatory cell accumulation and maintenance of inflammation in airway. Moreover, MMP-9 may contribute to cell migration, an important mechanism involved in the repair of the respiratory epithelium.     

小鼠肝癌细胞特异性淋巴道转移与其基质金属蛋白酶分泌的关系

目的　探讨肿瘤细胞基质金属蛋白酶 (MMPs)分泌与特异性淋巴结转移的关系。方法　将自建高、低转移小鼠肝癌细胞系HCa F(高转移 )和HCa P(低转移 )在培养时 ,分别加入淋巴结、肝脏或脾脏匀浆 ,离心收集培养上清 ,用明胶酶谱法检测两株癌细胞在不同培养环境下分泌的MMPs酶谱 ,分析两者的差异。结果　在单纯RPMI16 40培养基中HCa F和HCa P细胞仅能分泌少量MMP 9(12 5 6± 15 7,2 6 42± 385 ) ,加入淋巴结匀浆后HCa F细胞分泌MMP 9显著增强 (12 40 3± 894) ,且分泌MMP 9的活性型和MMP 2 ;HCa P细胞也分泌MMP 9(90 6 8± 6 86 )及其活性型 (3 914± 12 5 3)和MMP 2(2 997± 1990 ) ,但量均明显低于HCa F细胞 ;加入肝脏或脾脏匀浆后 ,HCa F和HCa P细胞均不分泌MMPs。结论　HCa F细胞强于HCa P细胞的转移能力可能与HCa F细胞分泌MMPs的能力强于HCa P细胞相关 ,而HCa F和HCa P细胞仅在淋巴结成分诱导下才能分泌较多的MMPs,这可能与它们具有特异性地向淋巴结转移的功能密切相关。     

AC impedance measurements on high copper dental amalgams

In recent years alloys with a high copper content were developed to improve the corrosion resistance of dental amalgam by elimination of the γ₂ (Sn-Hg) phase. The purpose of the present investigation was to compare the electrochemical behaviour of high copper amalgams obtained from single composition amalgam alloys (Indiloy; Shofu, Dental Corp., Menlo Park, USA) with those that used the additive mode of copper alloying (Dispersalloy; Johnson & Johnson, East Windsor, USA).