Violence exposure and resulting psychological effects suffered by psychiatric visiting nurses in Japan.

WHAT IS KNOWN ON THE SUBJECT?: There is a developing body of research on violence in healthcare workplaces. Although psychiatric visiting nurses (PVNs) are an important group of professionals who provide medical services for people with mental disorders live in the community, little is known about the experiences and characteristics of violence exposure among PVNs, or the characteristics and work situations of PVNs related to violence exposure. WHAT THIS STUDY ADDS TO EXISTING KNOWLEDGE?: Approximately 40% of participants were exposed to violence during the previous 12 months; approximately 50% had been exposed during their PVN careers in PVN settings. The most frequent violence was verbal abuse. Longer career length as a PVN and greater number of visits per month were both positively associated with verbal abuse during the previous 12 months. Twenty-eight of the 34 participants (83%) who completed the IES-R-J survey had some residual psychological distress, and two (6%) had a potentially high risk of posttraumatic stress disorder. WHAT ARE THE IMPLICATIONS FOR PRACTICE?: In devising policies and strategies against violence, PVN organizations and administrators should consider the characteristics of the violence, especially verbal abuse, as well as the characteristics and work situations of PVNs that are related to verbal abuse. Furthermore, they might provide relevant information on violence in PVN settings within their violence-prevention manuals or education. It would be important to provide support and to construct a safe workplace environment for PVNs who are experiencing residual psychological distress. ABSTRACT: Introduction Psychiatric visiting nurses (PVNs) play a crucial role by providing medical services for community-living individuals with mental disorders in Japan. However, little is known about violence towards PVNs. Aim This cross-sectional study investigated violence during visits and the resulting psychological effects for PVNs. Methods PVNs were assessed using a violence exposure questionnaire and the Impact of Event Scale-Revised (IES-R-J); a measure of posttraumatic distress. Result Thirty-eight (41%) of 94 participants had experienced violence during the previous 12 months and 49 (53%) over their entire career. The most frequent violence was verbal abuse. Career length as a PVN and number of visits per month were significantly positively associated with verbal abuse during the previous 12 months. The IES-R-J scores indicated 28 of the 34 participants who completed the questionnaire exhibited psychological distress for the most traumatic violence during their career and two had a potentially high risk of posttraumatic stress disorder. Discussion and Implications Policies and strategies aimed at reducing violence in PVN settings should be developed according to characteristics of the violence, as well as the characteristics and work situation of PVNs. Furthermore, the provision of support and a safe workplace environment would be important for PVNs with residual psychological distress.

Effects of emulsifying components in the continuous phase of cream on the stability of fat globules and the physical properties of whipped cream.

The emulsifying components in cream are very important in controlling the physical characteristics of whipped cream. The effects of those components on the stability of fat globules and the physical characteristics of whipped cream were investigated. A low-molecular-weight emulsifier, and protein ingredients such as sodium caseinate and a casein partial hydrolysate (casein peptides), were used as emulsifying components in this investigation. The viscosity of deaerated whipped cream (called the serum viscosity) was measured to evaluate the degree of fat-globule aggregation. Furthermore, the shape-retention ability, which is the degree of reduction in the firmness of whipped cream between immediately after whipping and after 1d of refrigeration, was explored. The addition of the low-molecular-weight emulsifier in the continuous phase of dairy cream, which does not contain added low-molecular-weight emulsifiers, increased the stability of the fat globules and reduced the shape-retention ability of the whipped cream. The addition of protein ingredients (sodium caseinate and casein peptides) to the continuous phase of dairy cream had little effect. However, the addition of casein peptide in the continuous phase of dairy cream together with the low-molecular-weight emulsifier reduced the effect of the low-molecular-weight emulsifier on the stabilization of fat globules and the shape-retention ability of the whipped cream. The addition of casein peptide did not recover the serum viscosity; thus, other mechanisms might underlie this phenomenon.

Variational necessary and sufficient stability conditions for inviscid shear flow.

A necessary and sufficient condition for linear stability of inviscid parallel shear flow is formulated by developing a novel variational principle, where the velocity profile is assumed to be monotonic and analytic. It is shown that unstable eigenvalues of Rayleigh's equation (which is a non-self-adjoint eigenvalue problem) can be associated with positive eigenvalues of a certain self-adjoint operator. The stability is therefore determined by maximizing a quadratic form, which is theoretically and numerically more tractable than directly solving Rayleigh's equation. This variational stability criterion is based on the understanding of Krein signature for continuous spectra and is applicable to other stability problems of infinite-dimensional Hamiltonian systems.

Statins inhibit tumor progression via an enhancer of zeste homolog 2-mediated epigenetic alteration in colorectal cancer.

While statin intake has been proven to reduce the risk of colorectal cancer (CRC), the mechanism of antitumor effects and clinical significance in survival benefits remain unclear. Statin-induced antiproliferative effects and its underlying mechanism were examined using six CRC cell lines. Statins except pravastatin showed antiproliferative effects (simvastatin ≥ fluvastatin > atorvastatin) even though both of simvastatin and pravastatin could activate mevalonate pathways, suggesting the statin-mediated antiproliferative effects depended on non-mevalonate pathway. Indeed, statin induced p27(KIP1) expression by downregulation of histone methyltransferase enhancer of zeste homolog 2 (EZH2), which acts as an epigenetic gene silencer. Additionally, the use of simvastatin plus classII histone deacetylase (HDAC) inhibitor (MC1568) induced further overexpression of p27(KIP1) by inhibiting HDAC5 induction originated from downregulated EZH2 in CRC cells and synergistically led to considerable antiproliferative effects. In the clinical setting, Statin intake (except pravastatin) displayed the downregulated EZH2 expression and inversely upregulated p27(KIP1) expression in the resected CRC by immunohistochemical staining and resulted in the significantly better prognoses both in overall survival (p = 0.02) and disease free survival (p < 0.01) compared to patients without statin intake. Statins may inhibit tumor progression via an EZH2-mediated epigenetic alteration, which results in survival benefits after resected CRC. Furthermore, statin plus classII HDAC inhibitor could be a novel anticancer therapy by their synergistic effects in CRC.

Cervicofacial subcutaneous emphysema associated with dental laser treatment.

Cervicofacial subcutaneous emphysema is a rare complication of dental procedures. Although most cases of emphysema occur incidentally with the use of a high-speed air turbine handpiece, there have been some reports over the past decade of cases caused by dental laser treatment. Emphysema as a complication caused by the air cooling spray of a dental laser is not well known, even though dental lasers utilize compressed air just as air turbines and syringes do. In this study, we comprehensively reviewed cases of emphysema attributed to dental laser treatment that appeared in the literature between January 2001 and September 2012, and we included three such cases referred to us. Among 13 cases identified in total, nine had cervicofacial subcutaneous and mediastinal emphysema. Compared with past reviews, the incidence of mediastinal emphysema caused by dental laser treatment was higher than emphysema caused by dental procedure without dental laser use. Eight patients underwent CO2 laser treatment and two underwent Er:YAG laser treatment. Nine patients had emphysema following laser irradiation for soft tissue incision. Dentists and oral surgeons should be cognizant of the potential risk for iatrogenic emphysema caused by the air cooling spray during dental laser treatment and ensure proper usage of lasers.

High-dose zoledronic acid narrows the periodontal space in rats.

The aim of this experiment was to evaluate the histological effects of zoledronic acid on the periodontal space in rats. 40 male Wistar rats were divided into three zoledronic acid groups and a control group. Zoledronic acid was injected subcutaneously at doses of 10, 50, or 500 µg/kg once a week for 3 weeks. The rats were killed 1 or 9 weeks after the last injection. Histological examination of the periodontal space around the incisor tooth revealed that zoledronic acid did not inhibit tooth development. In the rats killed 1 week after treatment discontinuation, the periodontal space gradually narrowed in response to increasing zoledronic acid doses, and the changes were statistically significant according to ANOVA but not according to ANOVA with post hoc tests. The changes persisted in the high-dose zoledronic acid group despite zoledronic acid discontinuation, with significant differences identified by ANOVA and ANOVA with post hoc tests. Therefore, although zoledronic acid had an insignificant effect on tooth development, it had a significant effect on the periodontal space when high doses were administered. The results of this experiment may provide useful information for future investigations on the role of zoledronic acid in the osteonecrosis of the jaw.

Distal pancreatectomy using a no-touch isolation technique.

BACKGROUND AND AIMS: Distal pancreatectomy is the only effective treatment for cancers of the pancreatic body and tail. The recurrence rate after DP has remained high. In an effort to over-come this problem, we developed a no-touch surgical technique for DP. This is a pilot study to see if distal pancreatectomy can be technically done using a no-touch surgical technique with-out deteriorating the post-operative prognosis. PATIENTS AND METHODS: From November 2000 through May 2011, 16 pancreatic ductal adeno-carcinoma patients have been operated on using a no-touch technique by a single operator. We described the surgical technique, and we reported our preliminary experience. During the procedure, the pancreatic body and tail is neither grasped nor squeezed by the surgeon. And all drainage vessels from the pancreatic body and tail are ligated and divided during the early phase of the operation. Furthermore, for improved dissection of the retroperitoneal tissue (rightward and posterior margins), we use a hanging and clamping maneuver and dissection behind Gerota's fascia. RESULTS: In the current series, the posterior and rightward resection margins were free in all patients, although seven were positive for anterior serosal invasion. The post-operative prognosis was not deteriorated with this technique. CONCLUSION: No-touch distal pancreatectomy technique may have some theoretical advantages, which merit future investigation in randomized controlled trials.

Mandibular reconstruction using 2-step bone transport in an irradiated cancer patient with type 2 diabetes mellitus.

This report describes mandibular reconstruction using a 2-step bone transport technique in a cancer patient with type 2 diabetes mellitus (DM) who received radiotherapy before ablative surgery. The bone, measuring 90 mm in length with the mandibular curvature and good alveolar form, was regenerated using a plate-guided method. Three implants were placed 21 months after completion of the first distraction and 14 months after the second distraction. These implants integrated successfully and have remained stable more than 2 years after loading. The results suggest that mandibular reconstruction using bone transport is possible after segmental osteotomy in irradiated cancer patients with DM, although a long treatment period is required.

Fibrinogen induces cytokine and collagen production in pancreatic stellate cells.

OBJECTIVE: Fibroblasts in the area of fibrosis in chronic pancreatitis and of the desmoplastic reaction associated with pancreatic cancer are now recognised as activated pancreatic stellate cells (PSCs). Recent studies have shown strong expression of fibrinogen, the central protein in the haemostasis pathway, in the stromal tissues of pancreatic cancer and chronic pancreatitis, suggesting that PSCs are embedded in and exposed to abundant fibrinogen in these pathological settings. The effects of fibrinogen on cell functions in PSCs were examined here. METHODS: PSCs were isolated from human pancreas tissues of patients undergoing operations for pancreatic cancer, and from rat pancreatic tissues. The effects of fibrinogen on key cell functions and activation of signalling pathways in PSCs were examined. RESULTS: Fibrinogen induced the production of interleukin 6 (IL6), interleukin 8 (IL8), monocyte chemoattractant protein-1, vascular endothelial growth factor, angiopoietin-1 and type I collagen, but not proliferation or intercellular adhesion molecule-1 expression. Fibrinogen increased alpha-smooth muscle actin expression and induced the activation of nuclear factor-kappaB (NF-kappaB), Akt and three classes of mitogen-activated protein kinases (extracellular signal-regulated kinase (ERK), c-Jun N-terminal kinase and p38 mitogen-activated protein kinase (MAPK)). Fibrinogen-induced IL6 and IL8 production was inhibited by antibodies against alpha(v)beta(3) and alpha(5)beta(1) integrins, suggesting that these integrins worked as counter receptors for fibrinogen in PSCs. In addition, fibrinogen-induced production of these cytokines was abolished by an inhibitor of NF-kappaB, and partially inhibited by inhibitors of ERK and p38 MAPK. CONCLUSION: Fibrinogen directly stimulated profibrogenic and proinflammatory functions in PSCs.

A loss-of-function p.G191R variant in the anionic trypsinogen (PRSS2) gene in Japanese patients with pancreatic disorders.

OBJECTIVE: There is a concept that pancreatitis results from an imbalance of proteases and their inhibitors within the pancreatic parenchyma. It has been recently shown that a loss-of-function variant, c.571G>A (p.G191R), in the anionic trypsinogen (PRSS2) gene protects against chronic pancreatitis in European populations. Here we examined the association of the p.G191R variant with pancreatic disorders in Japan. METHODS: Genomic DNA was prepared from 378 healthy controls and 604 patients with pancreatic disorders (241 patients with chronic pancreatitis, 174 with acute pancreatitis, and 189 with pancreatic neoplasm). Mutational analysis of the PRSS2 gene was performed by polymerase chain reaction-restriction fragment length polymorphism and direct sequencing. RESULTS: The heterozygous p.G191R variant was found in three of 241 (1.2%) patients with chronic pancreatitis, in seven of 174 (4.0%) patients with acute pancreatitis, and in 12 of 189 (6.3%) patients with pancreatic neoplasm. The p.G191R variant was found in 25 (two were homozygous and 23 were heterozygous) of 378 (6.6%) healthy controls. The p.G191R frequency in patients with chronic pancreatitis was lower than that in healthy controls (p = 0.001; odds ratio (OR) 0.178; 95% confidence interval (CI) = 0.057 to 0.561). The p.G191R frequency was lower in patients with alcoholic (0.9%; p = 0.015; OR, 0.132; 95% CI, 0.022 to 0.779) and idiopathic (1.0%; p = 0.025; OR, 0.144; 95% CI, 0.025 to 0.851) chronic pancreatitis than that in healthy controls. There were no statistical differences in the p.G191R frequency between healthy controls and patients with acute pancreatitis or with pancreatic neoplasm. Patients with alcoholic acute pancreatitis (n = 59) had no variant carrier, and the p.G191R frequency was lower than that in healthy controls (p = 0.035). CONCLUSION: The p.G191R variant protected against alcoholic and idiopathic chronic pancreatitis as well as alcoholic acute pancreatitis in Japan.

Vertical distraction of a free vascularized osteocutaneous scapular flap in the reconstructed mandible for implant therapy.

This paper describes a case of vertical distraction osteogenesis of a free vascularized osteocutaneous scapular flap in the reconstructed mandible before implant therapy. The patient was a 67-year-old woman with squamous cell carcinoma of the right lower gingiva. She underwent segmental mandibulectomy for tumor ablation and reconstruction with an osteocutaneous scapular flap. The distraction protocol, clinical course and implant therapy are presented. Through this procedure, the bone height of the scapular graft increased by 10mm. Implants with adequate length could be placed in the distracted area. Two years after masticatory loading, the condition of these implants was stable. Vertical distraction osteogenesis of the scapular flap was considered effective when performed before implant therapy, to facilitate postoperative functional and esthetic restoration after tumor resection.

Auricular chondritis caused by metal ear tagging in C57BL/6 mice.

Although it has been shown that auricular chondritis in rats is caused by the use of metal identification ear tags, the pathogenesis remains unclear. Based on the hypothesis that the auricular chondritis is caused by metal ions released from metal identification ear tags, we investigated the pathogenesis in male C57BL/6 mice tagged with metal identification ear tags. Twenty-six weeks after the attachment of the ear tags, visible increases in the thickness of the auricle were observed, and the concentrations of copper and iron in the tagged ears were significantly increased (P < .05) in the tagged ears compared with the untagged ears. There was up-regulation of metallothionein (MT)-I and MT-II mRNA in the tagged ears, and this was confirmed by immunohistologic staining of the destroyed cartilage. Histopathologically, there were observed severe chondritis with extensive granulomatous inflammation, newly formed cartilage nodules, and osseous metaplasia accompanied by cellular infiltrates, such as CD4 T lymphocyte, macrophages, neutrophils, and mast cells, and expression of Th1 cytokines, such as interferon-gamma, tumor necrosis factor-alpha, and interleukin-2 in the tagged ear. Based on these results, we concluded that the release of copper and iron ions from the metal ear tags played a major role in the onset of auricular chondritis. Subsequent cellular interactions, such as CD4 T cells, macrophages, fibroblasts, and mast cells, mediated by cytokines, such as tumor necrosis factor-alpha and interferon-gamma, caused an autoimmune response that may have led to the progression of auricular chondritis as an autoimmune disease.

Normal hepatic hemodynamics during early postoperative period in recipients with adult live donor liver transplantation.

To recognize "normal" hepatic hemodynamics after live donor liver transplantation (LDLT), we analyzed Doppler parameters on recipients with a right liver graft and donors after extended left hepatectomy. Theoretically these values should be the same. From April 2000 to October 2004, 20 LDLTs were performed using a right liver graft. The 10 recipients without postoperative complications and their donors were included in this study. Portal venous velocity (PVV; cm/s), hepatic arterial peak systolic velocity (cm/s), and hepatic venous peak velocity (HVPV; cm/s) were measured during the first 2 weeks. In donors PVV and HVPV after LDLT were significantly higher after than before left hepatectomy: 19.2 +/- 4.2 vs. 31.5 +/- 13.0 cm/s (P = .013) and 23.0 +/- 7.2 vs. 41.8 +/- 10.3 cm/s respectively (P = .010). However, there were mild degrees of increased PVV and HVPV. In recipients, a markedly increased PVV (106.3 +/- 45.2 cm/s on day 1) was significantly higher than that in donors on each postoperative day. The hepatic arterial resistive index in recipients was also significantly higher than that in donors on each postoperative day, for example, 0.72 +/- 0.11 vs 0.62 +/- 0.04 on day 1 (P = .0326). In conclusion, we have shown "abnormal" hepatic hemodynamics in even those recipients without complications during the early postoperative period after LDLT.

Development of leiomyosarcoma of the uterus in MMTV-CR-1 transgenic mice.

Overexpression of Cripto-1 (CR-1) in FVB/N mice using the MMTV-LTR promoter results in increased mammary tumourigenesis in these female transgenic mice (MMTV-CR-1). Here, we characterize uterine tumours that developed in 15/76 (19.7%) of MMTV-CR-1 female nulliparous or multiparous mice during 24 months of observation compared with 0/33 (0%) of FVB/N normal control mice observed during the same time period (p < 0.01). The uterine tumours collected from the MMTV-CR-1 mice were classified as leiomyosarcomas and found to express the CR-1 transgene by polymerase chain reaction analysis and immunohistochemistry. Detection by western blot analysis showed higher levels of phosphorylated (P) forms of c-src, Akt, GSK-3beta, and dephosphorylated (DP)-beta-catenin in lysates from MMTV-CR-1 uterine leiomyosarcomas in comparison with lysates from normal control FVB/N uteri. Immunostaining showed increased nuclear localization of beta-catenin in the MMTV-CR-1 uterine leiomyosarcomas. Increased immunostaining for CR-1 was detected in 9/13 (69.2%) cases of human leiomyosarcoma compared with staining in 3/15 (20%) human leiomyoma sections. Stronger immunostaining for P-src, P-Akt, P-GSK-3beta and increased nuclear localization of beta-catenin was also seen in human leiomyosarcomas in comparison with leiomyomas. Normal human uterine smooth muscle (UtSM) cells treated with exogenous soluble rhCR-1 showed increased levels of P-src, P-Akt, P-GSK-3beta and dephosphorylated (DP)-beta-catenin and increased proliferation (p < 0.05) and migration (p < 0.01) in comparison with untreated control UtSM cells. Inhibitors against c-src, Akt or beta-catenin, individually or in combination, significantly reduced CR-1-induced migration. These results suggest a role for CR-1 during uterine tumourigenesis either directly by activating c-src and Akt and/or via cross-talk with the canonical Wnt signalling pathway, as suggested by the increased expression of P-GSK-3beta, DP-beta-catenin, and increased nuclear localization of beta-catenin in human and MMTV-CR-1 mice leiomyosarcomas.

Anti-inflammatory sesquiterpenes from Curcuma zedoaria.

From the methanolic extract of the rhizome of Curcuma zedoaria, we isolated anti-inflammatory sesquiterpene furanodiene (1) and furanodienone (2) along with new sesquiterpene compound 3 and known eight sesquiterpenes, zederone (4), curzerenone (5), curzeone (6), germacrone (7), 13-hydroxygermacrone (8), dehydrocurdione (9), curcumenone (10), and zedoaronediol (11). Their structures were elucidated on the basis of spectroscopic data. The anti-inflammatory effect of isolated components on 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced inflammation of mouse ears were examined. Compounds 1 and 2 suppressed the TPA-induced inflammation of mouse ears by 75% and 53%, respectively, at a dose of 1.0 micromol. Their activities are comparable to that of indomethacin, the normally used anti-inflammatory agent.

Development of an in vitro skin sensitization test using human cell lines; human Cell Line Activation Test (h-CLAT). II. An inter-laboratory study of the h-CLAT.

Recent regulatory changes have placed a major emphasis on in vitro safety testing and alternative models. In regard to skin sensitization tests, dendritic cells (DCs) derived from human peripheral blood have been considered in the development of new in vitro alternatives. Human cell lines have been also reported recently. In our previous study, we suggested that measuring CD86 and/or CD54 expression on THP-1 cells (human monocytic leukemia cell line) could be used as an in vitro skin sensitization method. An inter-laboratory study among two laboratories was undertaken in Japan in order to further develop an in vitro skin sensitization model. In the present study, we used two human cell lines: THP-1 and U-937 (human histiocytic lymphoma cell line). First we optimized our test protocol (refer to the related paper entitled "optimization of the h-CLAT protocol" within this journal) and then we did an inter-laboratory validation with nine chemicals using the optimized protocol. We measured the expression of CD86 and CD54 on the above cells using flow cytometry after a 24h and 48h exposure to six known allergens (e.g., DNCB, pPD, NiSO(4)) and three non-allergens (e.g., SLS, tween 80). For the sample test concentration, four doses (0.1x, 0.5x, 1x, and 2x of the 50% inhibitory concentration (IC(50))) were evaluated. IC(50) was calculated using MTT assay. We found that allergens/non-allergens were better predicted using THP-1 cells compared to U-937 cells following a 24 h and a 48 h exposure. We also found that the 24h treatment time tended to have a better accuracy than the 48 h treatment time for THP-1 cells. Expression of CD86 and CD54 were good predictive markers for THP-1 cells, but for U-937 cells, expression of CD86 was a better predictor than CD54, at the 24h and the 48 h treatment time. The accuracy also improved when both markers (CD86 and CD54) were used as compared with a single marker for THP-1 cells. Both laboratories gave a good prediction of allergen/non-allergen, especially using THP-1 cells. These results suggest that our method, human Cell Line Activation Test (h-CLAT), using human cell lines THP-1 and U-937, but especially THP-1 cells at 24h treatment, may be a useful in vitro skin sensitization model to predict various contact allergens.

Development of an in vitro skin sensitization test using human cell lines: the human Cell Line Activation Test (h-CLAT). I. Optimization of the h-CLAT protocol.

The aim of this study is to optimize the experimental conditions for an in vitro skin sensitization test using the human cell lines THP-1 and U-937. As regards pre-culturing time, the expression of CD86 on DNCB-treated THP-1 cells tended to be higher after 48h and 72h pre-culture compared with other time points evaluated. Next, we investigated the effect of chemical treatment time, and found that induction of CD86 expression on THP-1 cells by DNCB reached a plateau after 24h. Augmentation of CD86 expression is often observed when cells are treated with a subtoxic dose of allergens. To determine the appropriate dose of test samples, the cytotoxicity of test samples to THP-1 and U-937 cells was assessed with MTT assay, and the 50% inhibitory concentration (IC50) of each test sample was calculated. Based on the cytotoxicity assay data, four concentrations in the range between toxic and non-toxic were selected (0.1x, 0.5x, 1x and 2x IC50). Several kinds of antibodies were tested for staining THP-1 and U-937 cells treated with allergens/non-allergens (e.g., DNCB, Ni/SLS), and suitable antibodies for staining CD86 and CD54 were selected. We confirmed that the working dilutions of the selected CD86 and CD54 antibodies were appropriate for use in our method. The effect of an FcR blocking procedure was also evaluated. The mean fluorescence intensity (MFI value) was decreased by the FcR blocking procedure, which indicated that non-specific staining was blocked. Therefore, this procedure should be included in the method. Based on our findings, the protocol for this assay was optimized and the experimental conditions to be used in a future validation study were identified. We propose to call this kind of in vitro skin sensitization test h-CLAT, which is short for human Cell Line Activation Test.

Involvement of MMP-7 in invasion of pancreatic cancer cells through activation of the EGFR mediated MEK-ERK signal transduction pathway.

AIMS: To clarify the involvement of matrix metalloproteinase-7 (MMP-7) in cell dissociation and the subsequent invasion of pancreatic cancer cells. METHODS: Western blotting, in vitro invasion assay, immunocytochemistry, and immunohistochemistry were performed in pancreatic cancer cell lines or pancreatic cancer tissue. RESULTS: The active form of the MMP-7 protein was expressed exclusively in the conditioned medium of dissociated (PC-1.0 and AsPC-1) pancreatic cancer cells, whereas proMMP-7 protein was only detected in the conditioned medium of non-dissociated (PC-1 and Capan-2) cells. Both intracellular and conditioned medium localised MMP-7 was greatly reduced by treatment with the epidermal growth factor receptor (EGFR) inhibitor AG1478 and the mitogen activated protein kinase kinase (MEK) inhibitor U0126 in pancreatic cancer cells. MMP-7 treatment significantly induced the disruption of tight junction (TJ) structures and subsequent cell dissociation, and activation of the EGFR mediated MEK- ERK (extracellular signal regulated protein kinase) signalling pathway in the non-dissociated pancreatic cancer cells. Moreover, the strong in vitro invasiveness of dissociated cells was inhibited by AG1478 and U0126 treatment, whereas the weak invasiveness of non-dissociated cells was apparently induced by MMP-7 treatment. In addition, MMP-7 expression was stronger at the invasive front than at the centre of human pancreatic tumours. CONCLUSION: MMP-7 is involved in cell dissociation and the subsequent invasion of pancreatic cancer cells. It induces the disruption of TJ structures and forms a positive feedback loop with activation of the EGFR mediated MEK-ERK signalling pathway.