Assessment of a circular powered stapler for creation of anastomosis in left-sided colorectal surgery: A prospective cohort study.

BACKGROUND: Circular staplers perform a critical function for creation of anastomoses in colorectal surgeries. Powered stapling systems allow for reduced force required by surgeons to fire the device and may provide advantages for creating a secure anastomosis. The objective of this study was to evaluate the clinical performance of a novel circular powered stapler in a post-market setting, during left-sided colectomy procedures. MATERIALS AND METHODS: Consecutive subjects underwent left-sided colorectal resections that included anastomosis performed with the ECHELON CIRCULAR™ Powered Stapler (ECP). The primary endpoint was the frequency in which a stapler performance issue was observed. Secondary endpoints included evaluation of ease of use of the device via a surgeon satisfaction questionnaire, and monitoring/recording of procedure-related adverse events (AEs). RESULTS: A total of 168 anastomoses were performed with the ECP. Surgical approaches included robotic-assisted (n = 74, 44.0%), laparoscopic (n = 71, 42.3%), open (n = 20, 11.9%), and hand-assisted minimally invasive (n = 3, 1.8%) procedures. There were 22 occurrences of device performance issues in 20 (11.9%) subjects during surgery. No positive intraoperative leak tests were observed, and only 1 issue was related to a procedure-related AE or surgical complication, which was an instance of incomplete surgical donut necessitating re-anastomosis. Postoperative anastomotic leaks were experienced in 4 (2.4%) subjects. Clavien-Dindo classification of all AEs indicated that 92.0% were Grades I or II. Participating surgeons rated the ECP as easier to use compared to previously used manual circular staplers in 85.7% of procedures. CONCLUSION: The circular powered stapler exhibited few clinically relevant performance issues, an overall favorable safety profile, and ease of use for creation of left-sided colon anastomoses.

Evaluation of a Powered Vascular Stapler in Video-Assisted Thoracic Surgery Lobectomy.

BACKGROUND: A narrow-profile powered vascular stapler (PVS) was developed to provide superior access and precise staple placement in thoracic procedures. The objective of this study was to determine if the PVS would yield an equivalent rate of hemostatic interventions compared with standard of care (SOC) staplers in video-assisted thoracoscopic surgery lobectomy. MATERIALS AND METHODS: A randomized, controlled, multicenter study was conducted comparing PVS with SOC staplers in lobectomies performed for non-small cell lung cancer. The primary performance endpoint was the incidence of intraoperative hemostatic interventions, and the primary safety endpoint was the frequency of postoperative bleeding-related interventions. RESULTS: A total of 98 subjects participated in the SOC group and 103 in the PVS group. Rates of intraoperative hemostatic interventions were 5.3% and 8.3% for the SOC and PVS groups, respectively. These rates were not statistically different (P = 0.137), although the upper bound of the 95% confidence interval for the difference in intervention rates between PVC and SOC exceeded a predefined 3% criterion for equivalence. Simple compressions were performed more frequently in the PVS subjects, which accounted for the higher intervention rate in this group. Postoperative interventions for bleeding were required in one SOC subject (1.0%) and one subject from the PVS group (0.9%). Procedure-related adverse events occurred in 21 (21.9%) SOC subjects and 23 (21.9%) PVS subjects, with no adverse events related to use of the study devices. CONCLUSIONS: The PVS exhibited similar overall safety and effectiveness to SOC staplers in video-assisted thoracoscopic surgery lobectomy.

Dose- and Time-Dependent Transcriptional Response of Ishikawa Cells Exposed to Genistein.

To further define the utility of the Ishikawa cells as a reliable in vitro model to determine the potential estrogenic activity of chemicals of interest, transcriptional changes induced by genistein (GES) in Ishikawa cells at various doses (10 pM, 1 nM, 100 nM, and 10 µM) and time points (8, 24, and 48 h) were identified using a comprehensive microarray approach. Trend analysis indicated that the expression of 5342 unique genes was modified by GES in a dose- and time-dependent manner (P ≤ 0.0001). However, the majority of gene expression changes induced in Ishikawa cells were elicited by the highest dose of GES evaluated (10 µM). The GES' estrogenic activity was identified by comparing the Ishikawa cells' response to GES versus 17 α-ethynyl estradiol (EE, at equipotent doses, ie, 10 µM vs 1 µM, respectively) and was defined by changes in the expression of 284 unique genes elicited by GES and EE in the same direction, although the magnitude of the change for some genes was different. Further, comparing the response of the Ishikawa cells exposed to high doses of GES and EE versus the response of the juvenile rat uterus exposed to EE, we identified 66 unique genes which were up- or down regulated in a similar manner in vivo as well as in vitro Genistein elicits changes in multiple molecular pathways affecting various biological processes particularly associated with cell organization and biogenesis, regulation of translation, cell proliferation, and intracellular transport; processes also affected by estrogen exposure in the uterus of the rat. These results indicate that Ishikawa cells are capable of generating a biologically relevant estrogenic response and offer an in vitro model to assess this mode of action.

Consistency and sealing of advanced bipolar tissue sealers.

OBJECTIVES: The aim of this study was to evaluate two commonly used advanced bipolar devices (ENSEAL(®) G2 Tissue Sealers and LigaSure™ Blunt Tip) for compression uniformity, vessel sealing strength, and consistency in bench-top analyses. METHODS: Compression analysis was performed with a foam pad/sensor apparatus inserted between closed jaws of the instruments. Average pressures (psi) were recorded across the entire inside surface of the jaws, and over the distal one-third of jaws. To test vessel sealing strength, ex vivo pig carotid arteries were sealed and transected and left and right (sealed) halves of vessels were subjected to burst pressure testing. The maximum bursting pressures of each half of vessels were averaged to obtain single data points for analysis. The absence or presence of tissue sticking to device jaws was noted for each transected vessel. RESULTS: Statistically higher average compression values were found for ENSEAL(®) instruments (curved jaw and straight jaw) compared to LigaSure™, P<0.05. Moreover, the ENSEAL(®) devices retained full compression at the distal end of jaws. Significantly higher and more consistent median burst pressures were noted for ENSEAL(®) devices relative to LigaSure™ through 52 firings of each device (P<0.05). LigaSure™ showed a significant reduction in median burst pressure for the final three firings (cycles 50-52) versus the first three firings (cycles 1-3), P=0.027. Tissue sticking was noted for 1.39% and 13.3% of vessels transected with ENSEAL(®) and LigaSure™, respectively. CONCLUSION: In bench-top testing, ENSEAL(®) G2 sealers produced more uniform compression, stronger and more consistent vessel sealing, and reduced tissue sticking relative to LigaSure™.

The genomic response of Ishikawa cells to bisphenol A exposure is dose- and time-dependent.

A reliable in vitro model to determine the potential estrogenic activity of chemicals of interest is still unavailable. To further investigate the usefulness of a human-derived cell line, we determined the transcriptional changes induced by bisphenol A (BPA) in Ishikawa cells at various doses (1 nM, 100 nM, 10 microM, and 100 microM) and time points (8, 24 and 48 h) by comparing the response of approximately 38,500 human genes and ESTs between treatment groups and controls (vehicle-treated). By trend analysis, we determined that the expression of 2794 genes was modified by BPA in a dose- and time-dependent manner (p< or =0.0001). However, the majority of gene expression changes induced in Ishikawa cells were elicited by the highest doses of BPA evaluated (10-100 microM), while the genomic response of the cells exposed to low doses of BPA was essentially negligible. By comparing the Ishikawa cells' response to BPA vs.17 alpha-ethynyl estradiol we determined that the change in the expression of 307 genes was identical in the direction of the change, although the magnitude of the change for some genes was different. Further, the response of Ishikawa cells to high doses of BPA shared similarities to the estrogenic response of the rat uterus, specifically, 362 genes were regulated in a similar manner in vivo as well as in vitro. Gene ontology analysis indicated that BPA results in changes to multiple molecular pathways affecting various biological processes particularly associated with cell organization and biogenesis, regulation of translation, cell proliferation, and intracellular transport; processes also affected by estrogen exposure in the uterus of the rat. These results indicate that Ishikawa cells are capable of generating a biologically relevant estrogenic response after exposure to chemicals with varied estrogenic activity, and offer an in vitro model to assess this mode of action.

The genomic response of a human uterine endometrial adenocarcinoma cell line to 17alpha-ethynyl estradiol.

We have determined the gene expression profile induced by 17 alpha-ethynyl estradiol (EE) in Ishikawa cells, a human uterine-derived estrogen-sensitive cell line, at various doses (1 pM, 100 pM, 10 nM, and 1 microM) and time points (8, 24, and 48 h). The transcript profiles were compared between treatment groups and controls (vehicle-treated) using high-density oligonucleotide arrays to determine the expression level of approximately 38,500 human genes. By trend analysis, we determined that the expression of 2560 genes was modified by exposure to EE in a dose- and time-dependent manner (p

The F-domain of estrogen receptor-alpha inhibits ligand induced receptor dimerization.

The role of the carboxyl terminal F-domain of estrogen receptor (ERalpha) is uncertain, but evidence suggests that this region may impart internal restraint on ER dimerization in the presence of 17beta-estradiol (E2). To identify the C-terminal residues affecting human ERalpha activation, we created a series of deletions and examined E2 induced receptor dimerization and transactivation. Deletion of the final 24 C-terminal amino acids of the F-domain (Delta7b) yielded a fivefold increase in dimerization, when compared to wild type (wt) ERalpha in the presence of 2nM E2, utilizing a yeast two-hybrid assay. This increase in dimerization is similar to that observed when the entire F-domain was deleted. Measurement of mutant:mutant homodimer formation yielded similar increases compared to mutant:wt interactions. Interestingly, a point mutation at the C-terminus (mut 3) showed increases in dimerization comparable to that of Delta7b in the presence of nanomolar amounts of E2. However, at sub-nanomolar levels of E2, mut 3 behaved similarly to wt ERalpha, whereas Delta7b maintained striking increases in dimerization. Determination of E2 binding affinity (Kd) constants revealed only marginal differences for wt and F-domain mutants, suggesting that the F-domain affects dimerization directly. We also observed enhanced interaction of F domain mutants with p160 family coactivator SRC1. Finally, transcriptional regulation of estrogen responsive reporters, 2XERE-LacZ and 3XERE-Luc in yeast and mammalian cells, respectively, reflected the increased propensity for dimerization by F domain mutants. Together, these data indicate that the C-terminal amino acids of ERalpha are critical for attenuation of E2 induced receptor dimerization and transcriptional activity.

Gene expression profiling reveals novel regulation by bisphenol-A in estrogen receptor-alpha-positive human cells.

Bisphenol-A (BPA) shows proliferative actions in uterus and mammary glands and may influence the development of male and female reproductive tracts in utero or during early postnatal life. Because of its ability to function as an estrogen receptor (ER) agonist, BPA has the potential to disrupt normal endocrine signaling through regulation of ER target genes. Some genes are regulated by both estradiol (E2) and BPA, but those exclusive to either agent have not been described. Using a yeast strain incorporating a vitellogenin A2 ERE-LacZ reporter gene into the genome, we found that BPA induced expression of the reporter in colonies transformed with the ERalpha expression plasmid, illustrating BPA-mediated regulation within a chromatin context. Additionally, a reporter gene transiently transfected into the endometrial cancer (Ishikawa) cell line also showed BPA activity, although at 100-fold less potency than E2. To compare global gene expression in response to BPA and E2, we used a variant of the MCF-7 breast cancer cell line stably expressing HA-tagged ERalpha. Cultures were treated for 3h with an ethanol vehicle, E2 (10(-8)M), or BPA (10(-6)M), followed by isolation of RNA and microarray analysis with the human U95A probe array (Affymetrix, Santa Clara, CA, USA). More than 300 genes were changed 2-fold or more by either or both agents, with roughly half being up-regulated and half down-regulated. A number of growth- and development-related genes, such as HOXC1 and C6, Wnt5A, Frizzled, TGFbeta-2, and STAT inhibitor 2, were found to be affected exclusively by BPA. We used quantitative real-time PCR to verify regulation of the HOXC6 gene, which showed decreased expression of approximately 2.5-fold by BPA. These results reveal novel effects by BPA and E2, raising interesting possibilities regarding the role of endocrine disruptors in sexual development.

Bisphenol-A and estradiol exert novel gene regulation in human MCF-7 derived breast cancer cells.

Xenoestrogens such as bisphenol-A (BPA) can mimic endogenous 17beta-estradiol (E2) in vitro and in vivo through binding the estrogen receptor (ER), and modulating target gene expression. In the present study, we compared global gene regulation by BPA and E2 in estrogen responsive (ERalpha-HA) human breast cancer cells derived from the MCF-7 cell line. The ERalpha-HA cells (stably over-expressing ERalpha) were exposed to E2 (10(-8)M) or BPA (10(-6)M), for 3h followed by analysis of global gene expression. More than 40 transcripts were significantly changed in ERalpha-HA cells, with many being unique to BPA. At least 15 genes were modulated by BPA in the ER-null C4-12 cell line, indicating ER independent activity. Utilizing quantitative reverse transcription-polymerase chain reaction (RT-PCR), we confirmed BPA and E2 mediated regulation of four selected genes. A consensus Alu-type estrogen responsive element (ERE) was found in the Wiskott-Aldrich syndrome protein (WASP) gene, which conferred responsiveness to BPA and E2 in a reporter gene assay. Significant stimulation was seen only in ERalpha expressing cells, thus indicating a functional ERE. Taken together these data illustrate novel gene regulation by BPA and E2, which has implications for in vivo actions and previous reports of additive and synergistic effects on breast cancer cell growth.

Mutation of serines 104, 106, and 118 inhibits dimerization of the human estrogen receptor in yeast.

Ligand-dependent dimerization and phosphorylation participate in regulating transcriptional activation of the estrogen receptor-alpha (ER). We investigated the role of serines 104, 106, and 118 located in the activation function-1 (AF-1) domain of ER in ligand-induced receptor dimerization. These serines, previously documented as important sites for transactivation, were mutated to alanine, and yeast genetic systems were used to determine their effect on receptor dimerization and transcriptional activity. The serine to alanine mutants resulted in 50-80% decreased dimerization in response to 17beta-estradiol, while having modest effects on ER-mediated transactivation. We further demonstrated that ER expressed in yeast became hyperphosphorylated in the presence of estradiol, most likely at a site(s) different than the serines under investigation. Ligand-induced phosphorylation was inhibited by U0126 indicating that the ER was phosphorylated via the MAPK pathway. Taken together, these data indicate that serines 104, 106, and 118 are important for ligand-dependent ER dimerization, and that MAP kinase mediated phosphorylation may be important for ER function, in yeast model systems.

Xenoestrogen exposure and mechanisms of endocrine disruption.

Environmental xenoestrogens can be divided into natural compounds (e.g. from plants or fungi), and synthetically derived agents including certain drugs, pesticides and industrial by-products. Dietary exposure comes mainly from plant-derived phytoestrogens, which are thought to have a number of beneficial actions. However, high levels of exogenous estrogens including several well-known synthetic agents are associated with harmful effects. Chemicals like xenoestrogens, which can mimic endogenous hormones or interfere with endocrine processes, are collectively called endocrine disruptors. Adverse effects by endocrine disrupting chemicals (particularly xenoestrogens) include a number of developmental anomalies in wildlife and humans. Critical periods of urogenital tract and nervous system development in-utero and during early post-natal life are especially sensitive to hormonal disruption. Furthermore, damage during this vulnerable time is generally permanent, whereas in adulthood, ill effects may sometimes be alleviated if the causative agent is removed. The most commonly studied mechanism in which xenoestrogens exert their effects is through binding and activation of estrogen receptors a and similar to endogenous hormone. However, endocrine disruptors can often affect more than one hormone (sometimes in opposite directions), or different components of the same endocrine pathway, therefore making it difficult to predict effects on human health. In addition, xenoestrogens have the potential to exert tissue specific and nongenomic actions, which are sensitive to relatively low estrogen concentrations. The true risk to humans is a controversial issue; to date, little evidence exists for clear-cut relationships between xenoestrogen exposure and major human health concerns. However, because of the complexity of their mechanism and potential for adverse effects, much interest remains in learning how xenoestrogens affect normal estrogen signaling.

Nongenomic activity and subsequent c-fos induction by estrogen receptor ligands are not sufficient to promote deoxyribonucleic acid synthesis in human endometrial adenocarcinoma cells.

Estrogen 17beta-estradiol (E2) rapidly modulates several signaling pathways related to cell growth, preservation, and differentiation. The physiological role of these nongenomic effects with regard to downstream outcomes, and the relationship with transcriptional estrogen activity are unclear. Furthermore, the ability of selective estrogen receptor modulators (SERMs) to trigger nongenomic actions is largely unknown. To determine whether estrogen receptor (ER) ligands exert nongenomic activity in endometrial adenocarcinoma cells, and whether this activity affects transcription and DNA synthesis, we challenged human Ishikawa cells with E2 or partial ER agonists 4-hydroxytamoxifen (OHT) and raloxifene (ral). Serum-starved Ishikawa cells exposed for 5 min to 0.1 nM E2 showed induced phosphorylation of MAPK (ERK1/2). Ral and 4-OHT each at 1 nM also stimulated ERK in a rapid transient manner. E2 and 4-OHT induced proto-oncogene c-fos mRNA expression in Ishikawa cells within 30 min, but ral had no effect. In contrast to nongenomic action, only E2 stimulated expression of an estrogen response element (ERE)-driven luciferase (LUC) reporter gene. To examine DNA synthesis, [(3)H]-thymidine incorporation was measured in serum-starved cultures exposed to E2 or partial agonists for 2 d. E2 at 1 nM stimulated thymidine uptake in an ERK-dependent manner, but 1 nM 4-OHT, 1 nM ral, and 0.1-nM concentrations of E2 had no significant effects. Taken together, these data indicate that both nongenomic and direct transcriptional ER effects are likely required to promote DNA synthesis.