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PLZF expression maps the early stages of ILC1 lineage development. - Proceedings of the National Academy of Sciences of the United States of America
Among the variety of tissue-resident NK-like populations recently distinguished from recirculating classical NK (cNK) cells, liver innate lymphoid cells (ILC) type 1 (ILC1s) have been shown to represent a distinct lineage that originates from a novel promyelocytic leukaemia zinc finger (PLZF)-expressing ILC precursor (ILCP) strictly committed to the ILC1, ILC2, and ILC3 lineages. Here, using PLZF-reporter mice and cell transfer assays, we studied the developmental progression of ILC1s and demonstrated substantial overlap with stages previously ascribed to the cNK lineage, including pre-pro-NK, pre-NK precursor (pre-NKP), refined NKP (rNKP), and immature NK (iNK). Although they originated from different precursors, the ILC1 and cNK lineages followed a parallel progression at early stages and diverged later at the iNK stage, with a striking predominance of ILC1s over cNKs early in ontogeny. Although a limited set of ILC1 genes depended on PLZF for expression, characteristically including Il7r, most of these genes were also differentially expressed between ILC1s and cNKs, indicating that PLZF together with other, yet to be defined, factors contribute to the divergence between these lineages.
Pyranone natural products as inspirations for catalytic reaction discovery and development. - Accounts of chemical research
Natural products continue to provide a wealth of opportunities in the areas of chemical and therapeutic development. These structures are effective measuring sticks for the current state of chemical synthesis as a field and constantly inspire new approaches and strategies. Tetrahydropryans and tetrahydropyran-4-ones are found in numerous bioactive marine natural products and medicinal compounds. Our interest in exploring the therapeutic potential of natural products containing these motifs provided the impetus to explore new methods to access highly functionalized, chiral pyran molecules in the most direct and rapid fashion possible. This goal led to exploration and development of a Lewis acid-mediated Prins reaction between a chiral Î²-hydroxy-dioxinone and aldehyde to produce a pyran-dioxinone fused product that can be processed in a single pot operation to the desired tetrahydropyran-4-ones in excellent yield and stereoselectivity. Although the Prins reaction is a commonly employed approach toward pyrans, this method uniquely provides a 3-carboxy-trisubstituted pyran and utilizes dioxinones in a manner that was underexplored at the time. The 3-carboxy substituent served as a key synthetic handhold when this method was applied to the synthesis of highly functionalized pyrans within the macrocyclic natural products neopeltolide, okilactiomycin, and exiguolide. When employed in challenging macrocyclizations, this tetrahydropyranone forming reaction proved highly stereoselective and robust. Another major thrust in our lab has been the synthesis of benzopyranone natural products, specifically flavonoids, because this broad and diverse family of compounds possesses an equally broad range of biological and medicinal applications. With the goal of developing a broad platform toward the synthesis of enantioenriched flavonoid analogs and natural products, a biomimetic, asymmetric catalytic approach toward the synthesis of 2-aryl benzopyranones was developed. A bifunctional hydrogen bonding/BrÃ¸nstead base catalyst was ultimately found to enable this transformation in analogous manner to the biosynthesis via the enzyme chalcone isomerase. Employing thiourea catalysts derived from the pseudoenantiomeric quinine and quinidine, alkylidene Î²-ketoesters can be isomerized to 3-carboxy flavanones and decarboxylated in a single pot operation to stereodivergently provide highly enantioenriched flavanones in excellent yield. This method was applied to the synthesis of the abyssinone family of natural products, as well as the rotenoid, deguelin. An analogous method to isomerize chalcones was developed and applied to the synthesis of isosilybin A. In both of these related endeavors, the need for novel enabling methodologies toward the efficient creation of targeted molecular complexity drove the discovery, development and deployment of these stereoselective catalytic transformations.
A biomimetic strategy to access the silybins: total synthesis of (-)-isosilybin A. - Organic letters
We report the first asymmetric, total synthesis of (-)-isosilybin A. A late-stage catalytic biomimetic cyclization of a highly functionalized chalcone is employed to form the characteristic benzopyranone ring. A robust and flexible approach to this chalcone provides an entry to the preparation of the entire isomeric family of silybin natural products.
Elevated T cell receptor signaling identifies a thymic precursor to the TCRÎ±Î²(+)CD4(-)CD8Î²(-) intraepithelial lymphocyte lineage. - Immunity
The origin and developmental pathway of intestinal T cell receptor Î±Î²(+) CD4(-)CD8Î²(-) intraepithelial lymphocytes (unconventional iIELs), a major population of innate-like resident cytolytic T cells, have remained elusive. By cloning and expressing several TCRs isolated from unconventional iIELs, we identified immature CD4(lo)CD8(lo)(DP(lo))CD69(hi)PD-1(hi) thymocytes as the earliest postsignaling precursors for these cells. Although these precursors displayed multiple signs of elevated TCR signaling, a sizeable fraction of them escaped deletion to selectively engage in unconventional iIEL differentiation. Conversely, TCRs cloned from DP(lo)CD69(hi)PD-1(hi) thymocytes, a population enriched in autoreactive thymocytes, selectively gave rise to unconventional iIELs upon transgenic expression. Thus, the unconventional iIEL precursor overlaps with the DP(lo) population undergoing negative selection, indicating that, concomitant with the downregulation of both CD4 and CD8 coreceptors, a balance between apoptosis and survival signals results in outcomes as divergent as clonal deletion and differentiation to the unconventional iIEL lineage.Copyright Â© 2014 Elsevier Inc. All rights reserved.
A negative feedback loop mediated by the Bcl6-cullin 3 complex limits Tfh cell differentiation. - The Journal of experimental medicine
Induction of Bcl6 (B cell lymphoma 6) is essential for T follicular helper (Tfh) cell differentiation of antigen-stimulated CD4(+) T cells. Intriguingly, we found that Bcl6 was also highly and transiently expressed during the CD4(+)CD8(+) (double positive [DP]) stage of T cell development, in association with the E3 ligase cullin 3 (Cul3), a novel binding partner of Bcl6 which ubiquitinates histone proteins. DP stage-specific deletion of the E3 ligase Cul3, or of Bcl6, induced the derepression of the Bcl6 target genes Batf (basic leucine zipper transcription factor, ATF-like) and Bcl6, in part through epigenetic modifications of CD4(+) single-positive thymocytes. Although they maintained an apparently normal phenotype after emigration, they expressed increased amounts of Batf and Bcl6 at basal state and produced explosive and prolonged Tfh responses upon subsequent antigen encounter. Ablation of Cul3 in mature CD4(+) splenocytes also resulted in dramatically exaggerated Tfh responses. Thus, although previous studies have emphasized the essential role of Bcl6 in inducing Tfh responses, our findings reveal that Bcl6-Cul3 complexes also provide essential negative feedback regulation during both thymocyte development and T cell activation to restrain excessive Tfh responses.Â© 2014 Mathew et al.
A committed precursor to innate lymphoid cells. - Nature
Innate lymphoid cells (ILCs) specialize in the rapid secretion of polarized sets of cytokines and chemokines to combat infection and promote tissue repair at mucosal barriers. Their diversity and similarities with previously characterized natural killer (NK) cells and lymphoid tissue inducers (LTi) have prompted a provisional classification of all innate lymphocytes into groups 1, 2 and 3 solely on the basis of cytokine properties, but their developmental pathways and lineage relationships remain elusive. Here we identify and characterize a novel subset of lymphoid precursors in mouse fetal liver and adult bone marrow that transiently express high amounts of PLZF, a transcription factor previously associated with NK T cell development, by using lineage tracing and transfer studies. PLZF(high) cells were committed ILC progenitors with multiple ILC1, ILC2 and ILC3 potential at the clonal level. They excluded classical LTi and NK cells, but included a peculiar subset of NK1.1(+)DX5(-) 'NK-like' cells residing in the liver. Deletion of PLZF markedly altered the development of several ILC subsets, but not LTi or NK cells. PLZF(high) precursors also expressed high amounts of ID2 and GATA3, as well as TOX, a known regulator of PLZF-independent NK and LTi lineages. These findings establish novel lineage relationships between ILC, NK and LTi cells, and identify the common precursor to ILCs, termed ILCP. They also reveal the broad, defining role of PLZF in the differentiation of innate lymphocytes.
Light induced and circadian effects on retinal photoreceptor cell crystallins. - Photochemistry and photobiology
Crystallins in the retina may serve a chaperone-like protective function. In this study we measured mRNA levels for alpha-, beta- and gamma-crystallins in rat retinas following treatment with potentially damaging levels of light. We also determined crystallin protein patterns in photoreceptor cell rod outer segments (ROSs) isolated from rats exposed to intense light. Weanling albino rats were maintained in a dim cyclic light environment or in darkness for 40days. At P60 animals were treated with intense visible light, for as long as 8h, beginning at various times of the day or night. Retinas were excised immediately after light treatment and used for quantitative RT-PCR, or to prepare ROSs for western analysis. Some eyes were frozen in OCT for crystallin immunohistochemistry. Intense light exposure led to increases in mRNA expression for all retinal crystallins and to changes in ROS crystallin immunoreactivity. These light-induced changes were found to depend on the time of day that exposure started, duration of light treatment and previous light rearing history. We suggest that crystallin synthesis in retina exhibits a dependence on both light stress and circadian rhythm and that within photoreceptor cells crystallins appear to migrate in a light-independent, circadian fashion.Â© 2010 The Authors. Photochemistry and Photobiology Â© 2010 The American Society of Photobiology.
Superhydrophilic surface modification of copper surfaces by Layer-by-Layer self-assembly and Liquid Phase Deposition of TiO(2) thin film. - Journal of colloid and interface science
A new method has been developed for the superhydrophilic surface modification of copper using versatile solution-based fabrication techniques. The high surface area of TiO(2) nanoparticles was exploited to create a thin film with increased surface energy that transformed copper materials from relatively hydrophobic to superhydrophilic. Copper exposed to ambient conditions resulting in a thin layer of copper oxide has a water contact angle near 90Â°, but following TiO(2) modification, the contact angle dropped to 0Â°. The thin film responsible for this drastic improvement in wettability proved durable by retaining its excellent properties throughout an extended application of thermal stress. SEM and Raman Spectroscopic analysis confirmed the structural integrity of the film before and after a durability test.Copyright Â© 2010 Elsevier Inc. All rights reserved.
Thick Silicon Double-Sided Strip Detectors for Low-Energy Small-Animal SPECT. - IEEE transactions on nuclear science
This work presents characterization studies of thick silicon double-sided strip detectors for a high-resolution small-animal SPECT. The dimension of these detectors is 60.4 mm Ã— 60.4 mm Ã— 1 mm. There are 1024 strips on each side that give the coordinates of the photon interaction, with each strip processed by a separate ASIC channel. Our measurement shows that intrinsic spatial resolution equivalent to the 59 Î¼m strip pitch is attainable. Good trigger uniformity can be achieved by proper setting of a 4-bit DAC in each ASIC channel to remove trigger threshold variations. This is particularly important for triggering at low energies. The thick silicon DSSD (Double-sided strip detector) shows high potential for small-animal SPECT.
Intrinsic functional defects of type 2 innate lymphoid cells impair innate allergic inflammation in promyelocytic leukemia zinc finger (PLZF)-deficient mice. - The Journal of allergy and clinical immunology
The transcription factor promyelocytic leukemia zinc finger (PLZF) is transiently expressed during development of type 2 innate lymphoid cells (ILC2s) but is not present at the mature stage. We hypothesized that PLZF-deficient ILC2s have functional defects in the innate allergic response and represent a tool for studying innate immunity in a mouse with a functional adaptive immune response.We determined the consequences of PLZF deficiency on ILC2 function in response to innate and adaptive immune stimuli by using PLZF(-/-) mice and mixed wild-type:PLZF(-/-) bone marrow chimeras.PLZF(-/-) mice, wild-type littermates, or mixed bone marrow chimeras were treated with the protease allergen papain or the cytokines IL-25 and IL-33 or infected with the helminth Nippostrongylus brasiliensis to induce innate type 2 allergic responses. Mice were sensitized with intraperitoneal ovalbumin-alum, followed by intranasal challenge with ovalbumin alone, to induce adaptive TH2 responses. Lungs were analyzed for immune cell subsets, and alveolar lavage fluid was analyzed for ILC2-derived cytokines. In addition, ILC2s were stimulated exÂ vivo for their capacity to release type 2 cytokines.PLZF-deficient lung ILC2s exhibit a cell-intrinsic defect in the secretion of IL-5 and IL-13 in response to innate stimuli, resulting in defective recruitment of eosinophils and goblet cell hyperplasia. In contrast, the adaptive allergic inflammatory response to ovalbumin and alum was unimpaired.PLZF expression at the innate lymphoid cell precursor stage has a long-range effect on the functional properties of mature ILC2s and highlights the importance of these cells for innate allergic responses in otherwise immunocompetent mice.Copyright Â© 2015 American Academy of Allergy, Asthma & Immunology. All rights reserved.
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