Publications by authors named "John F Rebhun"

Objective: To investigate the development of a minimal traditional Chinese medicine (TCM) formula using selected TCM ingredients and evaluating their biological activity with bone-specific tests. Finally, determining if the minimal formula can maintain bone mineral density (BMD) in a low bone mass (LBM)/osteoporosis (OP) model system.

Methods And Results: Sixteen different TCM plant extracts were tested for estrogenic, osteogenic and osteoclastic activities.

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Glycation and advanced glycation end products (AGE) damage skin which is compounded by AGE-induced oxidative stress and inflammation. Lip and facial skin could be susceptible to glycation damage as they are chronically stressed. As Gromwell (Lithospermum erythrorhizon) root (GR) has an extensive traditional medicine history that includes providing multiple skin benefits, our objective was to determine whether GR extract and its base naphthoquinone, shikonin, might protect skin by inhibiting glycation, increasing oxidative defenses, suppressing inflammatory responses and offering ultraviolet (UV) absorptive potential in lip and facial cosmetic matrices.

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Licorice, the root and stolons of the Glycyrrhiza plant (Fabaceae), has been used for centuries as a food additive (sweetener), in cosmetics, and in traditional medicine. In this research, we provide evidence that licorice extract activates peroxisome proliferator-activated receptor gamma (PPARγ) and, as identified through HPLC fractionation and mass spectroscopy, one of the activating phytochemicals is glabridin. Glabridin was shown to bind to and activate PPARγ.

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Lippia sidoides is an aromatic shrub that grows wild in the northeastern region of Brazil. In local traditional medicine, the aerial portions of this species are used as anti-infectives, antiseptics, spasmolytics, sedatives, hypotensives, and anti-inflammatory agents. In this research, we evaluate the potential immunological properties of Lippia extract through in vitro analysis of its ability to modulate intracellular cyclic adenosine monophosphate (cAMP) levels and interleukin-10 (IL-10) production.

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The dried unripe fruit from Evodia rutaecarpa Benth., known as Wu zhu yu in China, has long been used in traditional Chinese medicine. In this research, we provide evidence that evodia fruit extract activates peroxisome proliferator-activated receptor gamma (PPARγ) and, as identified through HPLC fractionation and mass spectroscopy, the activating phytochemical is evodiamine.

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Epac-1 and -2 (exchange proteins directly activated by cyclic AMP) are guanine-nucleotide exchange factors for the GTPases Rap1 and -2. Epac2 but not Epac1 was found to possess a RA (Ras association) domain similar to that found in the Ras effector Ral-GDS. This domain specifically bound Ras-GTP, enabling oncogenic Ras to translocate Epac2 from the cytosol to the plasma membrane.

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The detection of Ras-family GTPase activity is important in the determination of cell signaling events elicited by numerous ligands and cellular processes. This has been made much easier in recent years by the use of glutathione S-transferase (GST)-fused Ras binding domains. These domains from downstream effectors such as Raf and RalGDS preferentially bind the GTP-bound Ras proteins enabling their extraction and subsequent quantification by immunoblotting.

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Recently the tuberous sclerosis complex 2 (TSC2) tumor suppressor gene product has been identified as a negative regulator of protein synthesis upstream of the mTOR and ribosomal S6 kinases. Because of the homology of TSC2 with GTPase-activating proteins for Rap1, we examined whether a Ras/Rap-related GTPase might be involved in this process. TSC2 was found to bind to Rheb-GTP in vitro and to reduce Rheb GTP levels in vivo.

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GTPases of the Ras subfamily regulate a diverse array of cellular-signaling pathways, coupling extracellular signals to the intracellular response machinery. Guanine nucleotide exchange factors (GEFs) are primarily responsible for linking cell-surface receptors to Ras protein activation. They do this by catalyzing the dissociation of GDP from the inactive Ras proteins.

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Although a number of genetic defects are commonly associated with acute myeloid leukemia (AML), a large percentage of AML cases are cytogenetically normal. This suggests a functional screen for transforming genes is required to identify genetic mutations that are missed by cytogenetic analyses. We utilized a retrovirus-based cDNA expression system to identify transforming genes expressed in cytogenetically normal AML patients.

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