Connexin 43 mediated gap junctional communication enhances breast tumor cell diapedesis in culture

INTRODUCTION: Metastasis involves the emigration of tumor cells through the vascular endothelium, a process also known as diapedesis. The molecular mechanisms regulating tumor cell diapedesis are poorly understood, but may involve heterocellular gap junctional intercellular communication (GJIC) between tumor cells and endothelial cells. METHOD: To test this hypothesis we expressed connexin 43 (Cx43) in GJIC-deficient mammary epithelial tumor cells (HBL100) and examined their ability to form gap junctions, establish heterocellular GJIC and migrate through monolayers of human microvascular endothelial cells (HMVEC) grown on matrigel-coated coverslips. RESULTS: HBL100 cells expressing Cx43 formed functional heterocellular gap junctions with HMVEC monolayers within 30 minutes. In addition, immunocytochemistry revealed Cx43 localized to contact sites between Cx43 expressing tumor cells and endothelial cells. Quantitative analysis of diapedesis revealed a two-fold increase in diapedesis of Cx43 expressing cells compared to empty vector control cells. The expression of a functionally inactive Cx43 chimeric protein in HBL100 cells failed to increase migration efficiency, suggesting that the observed up-regulation of diapedesis in Cx43 expressing cells required heterocellular GJIC. This finding is further supported by the observation that blocking homocellular and heterocellular GJIC with carbenoxolone in co-cultures also reduced diapedesis of Cx43 expressing HBL100 tumor cells. CONCLUSION: Collectively, our results suggest that heterocellular GJIC between breast tumor cells and endothelial cells may be an important regulatory step during metastasis

Validation and Evaluation of Two Observational Pain Assessment Tools in a Trauma and Neurosurgical Intensive Care Unit

BACKGROUND: Studies have demonstrated that patients in the intensive care unit experience high levels of pain. While many of these patients are nonverbal at some point during their stay, there are few valid tools available to assess pain in this group

Validation and Evaluation of Two Observational Pain Assessment Tools in a Trauma and Neurosurgical Intensive Care Unit

BACKGROUND: Studies have demonstrated that patients in the intensive care unit experience high levels of pain. While many of these patients are nonverbal at some point during their stay, there are few valid tools available to assess pain in this group.OBJECTIVES: To evaluate the validity and clinical utility of two pain assessment tools, the revised Adult Non-Verbal Pain Scale (NVPS-R) and the Critical Care Pain Observation Tool (CPOT), in a trauma and neurosurgical patient population.METHODS: Patients were assessed using the NVPS-R and CPOT by trained intensive care unit nurses (n=23) and research assistants before, during and after two procedures: turning of the patient (nociceptive procedure) and noninvasive blood pressure cuff inflation (non-nociceptive procedure). Communicative patients were also asked to report their level of pain during each assessment.RESULTS: A total of 66 patients (34 communicative, 32 noncommunicative) were included in the study. CPOT and NVPS-R scores increased significantly when participants were exposed to turning, but not during noninvasive blood pressure measurement (repeated measures ANOVA: CPOT, F=5.81, P=0.019; NVPS-R, F=5.32, P=0.025) supporting discriminant validity. CPOT and NVPS-R scores were significantly higher during the turning procedure for patients who had indicated that they were in pain versus those who were not, indicating criterion validity. Inter-rater reliability was generally higher for the CPOT than NVPS-R. Nurses rated the feasibility of the two tools as comparable but provided higher ratings of acceptability for the CPOT.CONCLUSIONS: While the present study supports the use of the CPOT and the NVPS-R with critically ill trauma and neurosurgical patients, further research should explore the role of vital signs in pain.Peer Reviewe