Publications by authors named "David Farquhar"

Insulin resistance (IR) contributes to the pathophysiology of diabetes, dementia, viral infection, and cardiovascular disease. Drug repurposing (DR) may identify treatments for IR; however, barriers include uncertainty whether in vitro transcriptomic assays yield quantitative pharmacological data, or how to optimise assay design to best reflect in vivo human disease. We developed a clinical-based human tissue IR signature by combining lifestyle-mediated treatment responses (>500 human adipose and muscle biopsies) with biomarkers of disease status (fasting IR from >1200 biopsies).

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Article Synopsis
  • Learned associations between the environment and drug effects are key to understanding drug addiction, with specific neurons in the nucleus accumbens being activated by drugs and associated cues.
  • Researchers developed a new technique called the 'Daun02 inactivation method' to selectively inactivate neurons that have been activated by cocaine in a specific environment.
  • This innovative method allows for studying the causal roles of these neurons in behaviors linked to drug responses and other learned behaviors in rats.
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Poly-L-glutamic acid (PGA) has previously been demonstrated to be an effective backbone for creating a hydrophilic prodrug of the established anti-tumor agent, paclitaxel, the active agent in Taxol; this approach has obviated the need for the toxic Cremophor excipient, used to enhance the solubility of paclitaxel in the clinical formulation. In order to form hydrophilic prodrugs of the hydrophobic pro-apoptotic sphingolipid, N,N-dimethylsphingosine (DMSP), PGA was condensed with DMSP, previously modified with coumarin to allow spectroscopic detection during conjugate synthesis, to yield PGA-DMSP. Conjugates with different loadings of DMSP were prepared and evaluated for in vitro cytotoxicity against two human breast adenocarcinoma cell lines.

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Numerous human tumor types, including ovarian cancer, display a significant expression of the CD44 family of cell surface proteoglycans. To develop tumor-targeted drugs, we have initially evaluated whether the CD44 ligand hyaluronic acid (HA) could serve as a backbone for paclitaxel (TXL) prodrugs. HA-TXL was prepared by modification of previous techniques.

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Coumarin derivatives of N,N-dimethylsphingosine (DMSP) were prepared and chemically characterized. They were apparently biologically equivalent to DMSP in terms of tumor cell cytotoxicity and were used to establish the rapid mitochondrial localization of this sphingolipid in tumor cells, followed closely by its marked reduction of mitochondrial membrane potential.

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The L49 monoclonal antibody against the p97 antigen on melanomas and carcinomas was chemically conjugated to E. coli beta-galactosidase (beta-gal), forming a largely monomeric conjugate with preserved enzymatic activity. The resulting L49-beta-gal conjugate was used to activate (N-[(4"R,S)-4"-hexyloxy-4"-(1'''-O-beta-D-galactopyranosyl)butyl]daunorubicin) (1), a derivative of daunorubicin that has low cytotoxicity and high chemical stability.

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Purpose: We previously reported the synthesis of bis(pivaloyloxymethyl) 2',3'-dideoxyuridine 5'-monophosphate (POM2-ddUMP) (1a) as a membrane-transport prodrug formulation of the free parent nucleotide, ddUMP. Although successful at delivering ddUMP into cells in culture, POM2-ddUMP was rapidly degraded by plasma carboxylate esterases after intravenous administration to experimental animals, and therefore has limited therapeutic potential as a systemically administered prodrug. We now report the synthesis of bis(N,N'-dimethylcarbamoyloxymethyl)- and bis(N-piperidinocarbamoyloxymethyl) 2',3'-dideoxyuridine 5'-monophosphate [DM2-ddUMP (1b) and DP2-ddUMP (1c), respectively], analogues of POM2-ddUMP that were designed to be more resistant to degradation by plasma esterases.

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Bis(pivaloyloxymethyl) thymidine 5-phosphate (POM(2)-dTMP) has been investigated as a membrane-permeable prodrugs of dTMP. The growth inhibitory activity of POM(2)-TMP has been compared with thymidine (TdR) in wild type CCRF CEM cells (CEM) and a strain that lacks TdR kinase (CEM tk-). After 72 h incubation at 37 degrees C, TdR showed significant antiproliferative activity (IC(50)=27 microM) against CEM cells but was weakly effective (IC(50)=730 microM) against the mutant cell line.

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Paclitaxel (Taxol) has demonstrated clinical activity in non-small-cell lung cancer (NSCLC), but its use has not led to marked improvements in survival. This ineffectiveness can in part be attributed to inadequate delivery of effective drug levels to the lung via systemic administration and to drug resistance mechanisms. Locoregional drug administration and the use of drug copolymers are possible approaches to address these issues.

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Previous preclinical studies with ectopic tumor models have demonstrated remarkable improvements in the therapeutic profile of paclitaxel, formulated as a copolymer with poly-L-glutamic acid, compared with paclitaxel in the clinical formulation, Taxol. In this study, we evaluated these formulations in two human ovarian carcinoma xenograft models, NMP-1 and HEY, in nude mice. i.

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