A. Larry Arsenault

Bio: A. Larry Arsenault is an academic researcher from McMaster University. The author has contributed to research in topics: Transmission electron microscopy & Phospholipid. The author has an hindex of 14, co-authored 29 publications receiving 2808 citations. Previous affiliations of A. Larry Arsenault include University of British Columbia.

Anti-angiogenic compositions and methods of use

Abstract: The present invention provides compositions comprising an anti-angiogenic factor, and a polymeric carrier. Representative examples of anti-angiogenic factors include Anti-Invasive Factor, Retinoic acids and derivatives thereof, and paclitaxel. Also provided are methods for embolizing blood vessels, and eliminating biliary, urethral, esophageal, and tracheal/bronchial obstructions.

Exposure to HIV-1 directly impairs mucosal epithelial barrier integrity allowing microbial translocation.

Abstract: While several clinical studies have shown that HIV-1 infection is associated with increased permeability of the intestinal tract, there is very little understanding of the mechanisms underlying HIV-induced impairment of mucosal barriers. Here we demonstrate that exposure to HIV-1 can directly breach the integrity of mucosal epithelial barrier, allowing translocation of virus and bacteria. Purified primary epithelial cells (EC) isolated from female genital tract and T84 intestinal cell line were grown to form polarized, confluent monolayers and exposed to HIV-1. HIV-1 X4 and R5 tropic laboratory strains and clinical isolates were seen to reduce transepithelial resistance (TER), a measure of monolayer integrity, by 30–60% following exposure for 24 hours, without affecting viability of cells. The decrease in TER correlated with disruption of tight junction proteins (claudin 1, 2, 4, occludin and ZO-1) and increased permeability. Treatment of ECs with HIV envelope protein gp120, but not HIV tat, also resulted in impairment of barrier function. Neutralization of gp120 significantly abrogated the effect of HIV. No changes to the barrier function were observed when ECs were exposed to Env defective mutant of HIV. Significant upregulation of inflammatory cytokines, including TNF-α, were seen in both intestinal and genital epithelial cells following exposure to HIV-1. Neutralization of TNF-α reversed the reduction in TERs. The disruption in barrier functions was associated with viral and bacterial translocation across the epithelial monolayers. Collectively, our data shows that mucosal epithelial cells respond directly to envelope glycoprotein of HIV-1 by upregulating inflammatory cytokines that lead to impairment of barrier functions. The increased permeability could be responsible for small but significant crossing of mucosal epithelium by virus and bacteria present in the lumen of mucosa. This mechanism could be particularly relevant to mucosal transmission of HIV-1 as well as immune activation seen in HIV-1 infected individuals.

A model for the ultrastructure of bone based on electron microscopy of ion-milled sections.

Abstract: The relationship between the mineral component of bone and associated collagen has been a matter of continued dispute. We use transmission electron microscopy (TEM) of cryogenically ion milled sections of fully-mineralized cortical bone to study the spatial and topological relationship between mineral and collagen. We observe that hydroxyapatite (HA) occurs largely as elongated plate-like structures which are external to and oriented parallel to the collagen fibrils. Dark field images suggest that the structures (“mineral structures”) are polycrystalline. They are approximately 5 nm thick, 70 nm wide and several hundred nm long. Using energy-dispersive X-ray analysis we show that approximately 70% of the HA occurs as mineral structures external to the fibrils. The remainder is found constrained to the gap zones. Comparative studies of other species suggest that this structural motif is ubiquitous in all vertebrates.

Murine oncostatin M stimulates mouse synovial fibroblasts in vitro and induces inflammation and destruction in mouse joints in vivo.

Abstract: Oncostatin M (OSM) is a multifunctional cytokine, a member of the interleukin-6/leukemia inhibitory factor (IL-6/LIF) family, that can regulate a number of connective-tissue cell types in vitro including cartilage and synovial tissue-derived fibroblasts, however its role in joint inflammation in vivo is not clear. We have analyzed murine OSM (muOSM) activity in vitro and in vivo in mouse joint tissue, to determine the potential role of this cytokine in local joint inflammation and pathology. The effects of muOSM and other IL-6/LIF cytokines on mouse synovial fibroblast cultures were assessed in vitro and showed induction of monocyte chemotactic protein-1, interleukin-6, and tissue inhibitor metalloproteinase-1, as well as enhancement of colony growth in soft agarose culture. Other IL-6/LIF cytokines including IL-6, LIF, or cardiotrophin-1, did not have such effects when tested at relatively high concentrations (20 ng/ml). To assess effects of muOSM in articular joints in vivo, we used recombinant adenovirus expressing muOSM cDNA (AdmuOSM) and injected purified recombinant virus (106 to 108 pfu) intra-articularly into the knees of various mouse strains. Histological analysis revealed dramatic alterations in the synovium but not in synovium of knees treated with the control virus Ad-dl70 or knees treated with Adm-IL-6 encoding biologically active murine IL-6. AdmuOSM effects were characterized by increases in the synovial cell proliferation, infiltration of mononuclear cells, and increases in extracellular matrix deposition that were evident at day 4, but much more marked at days 7, 14, and 21 after administration. The synovium took on characteristics similar to pannus and appeared to contact and invade cartilage. Collectively, these results provide good evidence that OSM regulates synovial fibroblast function differently than other IL-6-type cytokines, and can induce a proliferative invasive phenotype of synovium in vivo in mice on overexpression. We suggest that OSM may contribute to pathology in arthritis.

Bone Marrow Stromal Stem Cells: Nature, Biology, and Potential Applications

Abstract: Bone marrow stromal cells are progenitors of skeletal tissue components such as bone, cartilage, the hematopoiesis-supporting stroma, and adipocytes. In addition, they may be experimentally induced to undergo unorthodox differentiation, possibly forming neural and myogenic cells. As such, they represent an important paradigm of post-natal nonhematopoietic stem cells, and an easy source for potential therapeutic use. Along with an overview of the basics of their biology, we discuss here their potential nature as components of the vascular wall, and the prospects for their use in local and systemic transplantation and gene therapy.

Coated implantable medical device

Abstract: A coated implantable medical device 10 includes a structure 12 adapted for introduction into the vascular system, esophagus, trachea, colon, biliary tract, or urinary tract; at least one layer 18 of a bioactive material positioned over the structure 12; and at least one porous layer 20 positioned over the bioactive material layer 18. Preferably, the structure 12 is a coronary stent, and the bioactive material is at least one of heparin, dexamethasone or a dexamethasone derivative. The device 10 includes layers 18 and 22 of heparin and dexamethasone, the layer 22 of dexamethasone being positioned above the layer 18 of heparin. The layers of bioactive material also can be individual materials or a combination of different materials. Unexpectedly, the more soluble heparin markedly promotes the release of the less soluble dexamethasone above it. The porous layer 20 is composed of a polymer applied by vapor or plasma deposition and provides a controlled release of the bioactive material. It is particularly preferred that the polymer is a polyimide, parylene or a parylene derivative, which is deposited without solvents, heat or catalysts, merely by condensation of a monomer vapor.

Anti-angiogenic compositions and methods of use

Abstract: The present invention provides compositions comprising an anti-angiogenic factor, and a polymeric carrier. Representative examples of anti-angiogenic factors include Anti-Invasive Factor, Retinoic acids and derivatives thereof, and paclitaxel. Also provided are methods for embolizing blood vessels, and eliminating biliary, urethral, esophageal, and tracheal/bronchial obstructions.

Therapeutic inhibitor of vascular smooth muscle cells

Abstract: Methods are provided for inhibiting stenosis following vascular trauma or disease in a mammalian host, comprising administering to the host a therapeutically effective dosage of a therapeutic conjugate containing a vascular smooth muscle binding protein that associates in a specific manner with a cell surface of the vascular smooth muscle cell, coupled to a therapeutic agent dosage form that inhibits a cellular activity of the muscle cell. Methods are also provided for the direct and/or targeted delivery of therapeutic agents to vascular smooth muscle cells that cause a dilation and fixation of the vascular lumen by inhibiting smooth muscle cell contraction, thereby constituting a biological stent.