Gregory Williams - US grants

This award to a Primarily Undergraduate Institution will support research in the general area of organometallic chemistry. The award will permit the participation of four undergraduates in the synthesis of new compounds which may be useful as homogeneous catalysts for structural transformations of organic compounds. The undergraduate participants will gain experience in the use of a number of essential spectroscopic tools, such as nuclear magnetic resonance and infrared spectroscopy. The focus of the research project is the chemical reactivity patterns of iron pentadienyl species, with specific emphasis on transformations at the metal center. The development of stereocontrolled carbon-carbon bond forming reactions is the central theme of the research. The four specific goals of the project are: 1. To define the fundamental mechanistic differences between the pentadienyl ligand and its two isoelectronic counterparts, cyclopentadienyl and pi-allyl; 2. To develop new synthetic routes to metal pentadienyl complexes which contain ancillary ligands other than neutral two-electron donors; 3. To develop the first general procedures for selective endo substitution of (polyolefin)metal complexes; 4. To provide the first general and versatile methods for functionalizing metal(polyolefin) complexes with electrophiles.

This proposal concerns the application of (Cycloheptatriene) Iron Tricarbonyl and (Cycloheptatrieneone) Iron Tricarbonyl to organic synthesis. Both of these have a number of attractive features which recommend their application to synthesis. Most importantly, the Fe(CO)3 fragment blocks one face of the coordinated ring, providing the opportunity for stereoselective carbon-carbon bond forming reactions. The proposal discusses methods for the simple elaboration of (C7H8)Fe(CO)3 and (C7H6O)Fe(CO)3. Building upon this methodology, several schemes for cyclization are considered. These include: side-chain nucleophilic attack on the coordinated diene, ring-centered enolate attack on the side chain and Lewis acid induced cyclization of a divinyl ketone. The methodology developed in this proposal will provide versatile intermediates for the stereocontrolled synthesis of conformationally labile natural products of interest to the health sciences.

The first part of this research will involve the development of a strategy for endo carbon-carbon bond formation that involves functional group manipulation at the metal center of (cycloheptadienyl)M(halide), where M is Fe or Ru. Conversion of the halide ligand to an appropriate organic group followed by reductive elimination will complete the functionalization. The second goal of the research will be to study the chemistry of carbanions stabilized by Fe(CO)3 and CpCo. The organometallic anions described are mild nucleophiles that will allow carbon-carbon bond formation with acyl and/or alkyl halides and BF3 activated carbonyl compounds. %%% With this Research in Undergraduate Institutions (RUI) award, the Synthetic Organic Program will support the research of Dr. Gregory M. Williams of the Department of Chemistry at California State University, Fullerton. The work is focused on two major areas, each of which will expand the utility of transition metal polyolefin complexes as precursors to natural products. In these areas, the attack of electron rich species on coordinated polyoefins and the chemistry of transition metal stabilized carbanions will be used for developing new ways to affect carbon-carbon bond formation.

The Department of Chemistry is purchasing a gas chromatography mass spectrometer (GC-MS). The instrument is being incorporated throughout the curriculum, from introductory courses for non-science majors to the senior research program for chemistry majors. Acquisition of the GC-MS is making possible the development of a new environmental chemistry program.

DESCRIPTION (provided by applicant): Temporomandibular joint disorders (TMJD), including osteoarthritis and internal derangement, have a high prevalence in the adult population and often cause pain and limited jaw function. Severe deterioration of the articular cartilage of the mandibular condyle can occur in advanced cases of TMJD and may necessitate surgical removal via condylectomy. Reconstruction of the mandibular condyle has been attempted using autogenous, allogeneic, and alloplastic grafts, but these implant materials are often associated with complications including donor site morbidity, risk of disease transmission, and immunogenic reaction. Tissue engineering of cartilage and bone may address the significant and unmet clinical need for treating TMJD through the ability to produce grafts with appropriate biological and mechanical properties. One approach to a tissue engineering based treatment for TMJD might be through the creation of an appropriately shaped chondral graft which could be used alone to resurface the condyle or integrated to an osseous substrate to reconstruct the entire condyle. The ability to shape cartilaginous tissues into anatomical forms could be an enabling technology to this treatment approach. Thus, the long-term goal of this project is to establish scientific principles and engineering methods for the creation of contoured articular cartilage grafts for the effective surgical treatment of TMJD. Recent studies have shown that shape changes can be induced in immature articular cartilage explants in vitro through the use of mechanical stimuli, particularly bending deformations. Our overall hypothesis is that the shape plasticity of articular cartilage may be differentially modulated by imbalances in proteoglycan (PG) and collagen (COL) remodeling (via BAPN or p-D-xyloside) and may be used advantageously to create grafts of the size and shape of human mandibular condyle cartilage. To test this hypothesis, we have two aims. Aim 1: Determine whether in vitro growth which favors PG or COL remodeling (via BAPN or P-D-xyloside, respectively) alters the shape plasticity of immature and mature articular cartilage. Aim 2: Determine whether chondral grafts of the size and shape of human mandibular condyle cartilage can be produced through the mechanical reshaping of articular cartilage explants. The successful outcome of this interdisciplinary study will be the identification of culture conditions and techniques which are conducive to the formation of anatomically shaped chondral tissues. These findings will have broad clinical implications for the use of regenerative medicine in the treatment of disorders of the TMJ and articulating joints, in general.

Project Summary This proposal aims to determine the contribution of T cells to pathology in an alpha-synuclein (?-syn) based mouse model of Parkinson disease (PD). Our lab has pursued the idea that ?-syn, an intracellular protein abnormally aggregated in PD brains, is a trigger for the innate immune and adaptive immune system activation associated with PD. Targeted overexpression of ?-syn in the substantia nigra of mice driven by an adeno-associated virus vector (AAV2-SYN) recapitulates the microgliosis, T cell infiltration, and slow progressive cell death observed in human PD. Additionally, knocking out antigen processing machinery (MHCII) reduces ?-syn induced inflammation and neurodegeneration, suggesting a possible T cell mediated disease mechanism. The proposed research attempts to build upon these findings, by investigating the hypothesis that activation of T cells is required for mediating the dopaminergic neurotoxicity of alpha-synuclein in vivo. First, proposed experiments will determine whether alpha synuclein can lead to T cell activation in an AAV2-SYN mouse model of PD. Changes in brain effector T cell populations will be measured through IHC and flow cytometry in BL6 mice injected with AAV2-SYN or a control AAV2 vector (AAV2-GFP) at 2, 4, and 12 weeks post-injection. Next, experiments to determine the effect of T cells on myeloid activation in response to ?-syn will be conducted. Changes in activated myeloid populations will be measured in AAV2-SYN treated BL6 and mice lacking CD4 T cells (either by genetic KO or pharmacological treatment) by IHC and flow cytometry 2, 4, and 12 weeks post injection. Lastly, the hypothesis that blocking T cells (either by genetic KO or pharmacological treatment) into the CNS will reduce the neurodegeneration associated with ?-syn overexpression will be tested. Both control BL6 mice and mice with a deficiency in CD4 T cells will be injected with AAV2-GFP and AAV2-SYN in the substantia nigra. Dopaminergic neuron loss will be assessed at 6 months post-injection with unbiased stereology. Collectively, the completion of these experiments will aid in the development of new therapeutics targeting T cells that work to prevent neuroinflammation as a neuroprotective treatment for Parkinson disease. The proposed training plan is sponsored by Dr. David Standaert and Dr. Ashley Harms. The overall goal of the training plan is to provide the PI with a solid foundation for a successful career as a research scientist studying neuroimmunology. Included in the training plan are experiences that help the PI: 1) gain competence in a variety of techniques integrating neurobiology and immunology, 2) collaborate with other scientists, 3) develop hypothesis-driven research, 4) present data in a written and oral format, 5) effectively integrate research with clinic, and 6) responsibly conduct research.