Arterial levels of oxygen stimulate intimal hyperplasia in human saphenous veins via a ROS-dependent mechanism.

Saphenous veins used as arterial grafts are exposed to arterial levels of oxygen partial pressure (pO2), which are much greater than what they experience in their native environment. The object of this study is to determine the impact of exposing human saphenous veins to arterial pO2. Saphenous veins and left internal mammary arteries from consenting patients undergoing coronary artery bypass grafting were cultured ex vivo for 2 weeks in the presence of arterial or venous pO2 using an established organ culture model.

Micro/nanoscale technologies for the development of hormone-expressing islet-like cell clusters.

Insulin-expressing islet-like cell clusters derived from precursor cells have significant potential in the treatment of type-I diabetes. Given that cluster size and uniformity are known to influence islet cell behavior, the ability to effectively control these parameters could find applications in the development of anti-diabetic therapies. In this work, we combined micro and nanofabrication techniques to build a biodegradable platform capable of supporting the formation of islet-like structures from pancreatic precursors.

Protandim attenuates intimal hyperplasia in human saphenous veins cultured ex vivo via a catalase-dependent pathway.

Human saphenous veins (HSVs) are widely used for bypass grafts despite their relatively low long-term patency. To evaluate the role of reactive oxygen species (ROS) signaling in intima hyperplasia (IH), an early stage pathology of vein-graft disease, and to explore the potential therapeutic effects of up-regulating endogenous antioxidant enzymes, we studied segments of HSV cultured ex vivo in an established ex vivo model of HSV IH. Results showed that HSV cultured ex vivo exhibit an ~3-fold increase in proliferation and ~3.

Arterial pO₂ stimulates intimal hyperplasia and serum stimulates inward eutrophic remodeling in porcine saphenous veins cultured ex vivo.

Ex vivo culture of arteries and veins is an established tool for investigating mechanically induced remodeling. Porcine saphenous veins (PSV) cultured ex vivo with a venous mechanical environment, serum-supplemented cell-culture medium and standard cell-culture conditions (5% CO₂ and 95% balance air ~140 mmHg pO₂) develop intimal hyperplasia (IH), increased cellular proliferation, decreased compliance and exhibit inward eutrophic remodeling thereby suggesting that nonmechanical factors stimulate some changes observed ex vivo. Herein we explore the contribution of exposure to greater than venous pO₂ and serum to these changes in cultured veins.

High throughput assembly of spatially controlled 3D cell clusters on a micro/nanoplatform.

Guided assembly of microscale tissue subunits (i.e. 3D cell clusters/aggregates) has found applications in cell therapy/tissue engineering, cell and developmental biology, and drug discovery.

Vacuum-assisted cell seeding in a microwell cell culture system.

We present a simple method to actively pattern individual cells and groups of cells in a polymer-based microdevice using vacuum-assisted cell seeding. Soft lithography is used to mold polymer microwells with various geometries on top of commercially available porous membranes. Cell suspensions are placed in a vacuum filtration setup to pull culture medium through the microdevice, trapping the cells in the microwells.

Endothelial actin and cell stiffness is modulated by substrate stiffness in 2D and 3D.

There is a growing appreciation of the profound effects that passive mechanical properties, especially the stiffness of the local environment, can have on cellular functions. Many experiments are conducted in a 2D geometry (i.e.

Effects of a black raspberry diet on gene expression in the rat esophagus.

A diet containing 5% freeze-dried black raspberries (BRB) markedly inhibits esophageal cancer in rats treated with the carcinogen, N-Nitrosomethylbenzylamine (NMBA). We previously identified esophageal genes that become dysregulated after short-term treatment of rats with NMBA and determined which genes are maintained at near-normal levels of expression if the animals were fed 5% BRB prior to and during NMBA treatment. In this study, we report the effects of the BRB diet on gene expression in esophagi from untreated (control) animals.

Carcinogen-altered genes in rat esophagus positively modulated to normal levels of expression by both black raspberries and phenylethyl isothiocyanate.

Our recent study identified 2,261 dysregulated genes in the esophagi of rats that received a 1-week exposure to the carcinogen N-nitrosomethylbenzylamine (NMBA). We further reported that 1,323 of these genes were positively modulated to near-normal levels of expression in NMBA-treated animals that consumed dietary phenylethyl isothiocyanate (PEITC), a constituent of cruciferous vegetables. Herein, we report our results with companion animals that were fed a diet containing 5% freeze-dried black raspberries (BRB) instead of PEITC.

The mouse and human Ah receptor differ in recognition of LXXLL motifs.

The aryl hydrocarbon receptor (AhR) is a ligand inducible transcription factor that exhibits interspecies differences, with the human and mouse AhR C-terminal transactivation domain sharing only 58% amino acid sequence identity. The AhR has a transactivation domain comprised of proline/serine/threonine-rich, glutamine-rich, and acidic amino acid subdomains. A truncated mAhR and hAhR containing only the acidic subdomain displayed widely differing transactivation potentials.

Effects of phenylethyl isothiocyanate on early molecular events in N-nitrosomethylbenzylamine-induced cytotoxicity in rat esophagus.

There is little information on early molecular events in the development of N-nitrosomethylbenzylamine (NMBA)-induced rat esophageal tumorigenesis and of the effects of chemopreventive agents on these events. In this study, we identified genes in rat esophagus that were differentially expressed in response to short-term NMBA treatment and modulated by cotreatment with phenylethyl isothiocyanate (PEITC). Rats were fed AIN-76A diet or AIN-76A diet containing PEITC for 3 weeks.

Modulation of N-nitrosomethylbenzylamine metabolism by black raspberries in the esophagus and liver of Fischer 344 rats.

Dietary freeze-dried black raspberries (BRBs) inhibit N-nitrosomethylbenzylamine (NMBA)-induced tumorigenesis in the Fischer 344 rat esophagus. To determine the mechanistic basis of the anti-initiating effects of BRBs, NMBA metabolism was studied in esophageal explant cultures and in liver microsomes taken from rats fed with AIN-76A diet or AIN-76A diet containing 5% or 10% BRBs. Five percent and 10% dietary BRBs inhibited NMBA metabolism in explants (26% and 20%) and in microsomes (22% and 28%), but the inhibition was not dose dependent.

Evidence that ligand binding is a key determinant of Ah receptor-mediated transcriptional activity.

The aryl hydrocarbon receptor (AhR) mediates the biological activity of 2,3,7,8-tetrachlorodibenzo-p-dioxin. Whether the AhR can mediate enhanced transcriptional activity in the absence of ligand binding has not been established. Hepatocytes from AhR-null (AhR-KO) and wild-type (AhR-WT) neonatal mice were immortalized with Simian virus 40.

The subdomains of the transactivation domain of the aryl hydrocarbon receptor (AhR) inhibit AhR and estrogen receptor transcriptional activity.

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) activates the aryl hydrocarbon receptor (AhR) to mediate transcriptional activity of dioxin-responsive genes. The transactivation domain (TAD) of human AhR (hAhR) has potentially distinct acidic, glutamine-rich, and proline/serine/threonine-rich subdomains. Cotransfection of exogenous hAhR into BP8 cells with isolated subdomains of hAhR TAD fused to glutathione S-transferase exhibited squelching of TCDD-dependent dioxin-response element (DRE)-driven luciferase reporter-gene activity with each subdomain.