In the gustatory system, the recognition of sugars, amino acids and bitter-tasting compounds is the function of specialized G protein-coupled receptors. Recently, two members of novel subfamily of G protein-coupled receptors were proposed to function as taste receptors based on their speci®c expression in taste receptor cells. Here, we report the identi®cation of a third member, T1R3, of this family of receptors. T1R3 maps near the telomere of mouse chromosome 4 rendering it a candidate for the Sac locus, a primary determinant of sweet preference in mice. Consistent with its candidacy for the Sac locus, T1R3 displays taste receptor cell-speci®c expression. In addition, taster and non-taster strains of mouse harbor different alleles of T1R3.

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Background Infection remains a dreaded complication after implantation of surgical prosthetics, particularly after hernia repair with synthetic mesh. We previously demonstrated the ability of a newly developed polymer to provide controlled release of an antibiotic in a linear fashion over 45 days. We subsequently showed that coating mesh with the drug-releasing polymer prevented a Staphylococcus aureus (SA) infection in vivo. In order to broaden the applicability of this technology, the polymer was synthesized as isolated “microspheres” and loaded with vancomycin (VM) before conducting a non-inferiority analysis. Materials and Methods Seventy-three mice underwent creation of a dorsal subcutaneous pocket that was inoculated with 104 CFU of green fluorescent protein (GFP)-labeled SA (105 CFU/ml). Multifilament polyester mesh (7*7mm) was placed into the pocket and the skin was closed. Mesh was either placed alone (n=16), coated with VM-loaded polymer (n=20), placed next to VM-loaded microspheres (n=20) or unloaded microspheres (n=10), or flushed with VM solution (n=7). Quantitative tissue/mesh cultures were performed at 2 and 4-weeks. Mice with open wounds and explanted mesh were excluded. Results Twenty-two of twenty-three (96%) tissue-mesh samples from mesh alone or empty miscrospheres were positive for GFP-labeled SA at two and four-weeks. Six of seven (86%) samples from the VM flush group were positive for GFP SA at 4 weeks. Thirty-eight of thirty-eight (100%) VM-loaded pCD-coated mesh or VM-loaded microspheres were negative for GFP SA at two and four weeks. Conclusion Slow affinity based drug-releasing polymers in the form of microspheres are able to adequately clear a bacterial burden of SA and prevent mesh infection.

Current post-operative standard of care for surgical procedures, including device implantations, dictates prophylactic antimicrobial therapy, but a percentage of patients still develop infections. Systemic antimicrobial therapy needed to treat such infections can lead to downstream tissue toxicities and generate drug-resistant bacteria. To overcome issues associated with systemic drug administration, a polymer incorporating specific drug affinity has been developed with the potential to be filled or refilled with antimicrobials, post-implantation, even in the presence of bacterial biofilm. This polymer can be used as an implant coating or stand-alone drug delivery device, and can be translated to a variety of applications, such as implanted or indwelling medical devices, and/or surgical site infections. The filling of empty affinity-based drug delivery polymer was analyzed in an in vitro filling/refilling model mimicking post-implantation tissue conditions. Filling in the absence of bacteria was compared to filling in the presence of bacterial biofilms of varying maturity to demonstrate proof-of-concept necessary prior to in vivo experiments. Antibiotic filling into biofilm-coated affinity polymers was comparable to drug filling seen in same affinity polymers without biofilm demonstrating that affinity polymers retain ability to fill with antibiotic even in the presence of biofilm. Additionally, post-implantation filled antibiotics showed sustained bactericidal activity in a zone of inhibition assay demonstrating post-implantation capacity to deliver filled antibiotics in a timeframe necessary to eradicate bacteria in biofilms. This work shows affinity polymers can fill high levels of antibiotics post-implantation independent of biofilm presence potentially enabling device rescue, rather than removal, in case of infection.

Background Venous neointimal hyperplasia and venous stenosis (VS) formation can result in a decrease in arteriovenous fistula (AVF) patency in patients with end‐stage renal disease. There are limited therapies that prevent VNH/VS. Systemic delivery of simvastatin has been shown to reduce VNH/VS but local delivery may help decrease the side effects associated with statin use. We determined if microparticles (MP) composed of cyclodextrins loaded with simvastatin (MP‐SV) could reduce VS/VNH using a murine arteriovenous fistula model with chronic kidney disease. Methods and Results Male C57BL/6J mice underwent nephrectomy to induce chronic kidney disease. Four weeks later, an arteriovenous fistula was placed and animals were randomized to 3 groups: 20 μL of PBS or 20 μL of PBS with 16.6 mg/mL of either MP or MP‐SV. Animals were euthanized 3 days later and the outflow veins were harvested for quantitative reverse transcriptase–polymerase chain reaction analysis and 28 days later for immunohistochemistical staining with morphometric analysis. Doppler ultrasound was performed weekly. Gene expression of vascular endothelial growth factor‐A ( Vegf‐A ), matrix metalloproteinase‐9 ( Mmp‐9 ), transforming growth factor beta 1 ( Tgf‐β1 ), and monocyte chemoattractant protein‐1 ( Mcp‐1 ) were significantly decreased in MP‐SV treated vessels compared with controls. There was a significant decrease in the neointimal area, cell proliferation, inflammation, and fibrosis, with an increase in apoptosis and peak velocity in MP‐SV treated outflow veins. MP‐SV treated fibroblasts when exposed to hypoxic injury had decreased gene expression of Vegf‐A and Mmp‐9 . Conclusions In experimental arteriovenous fistulas, periadventitial delivery of MP‐SV decreased gene expression of Vegf‐A , Mmp‐9 , Tgf‐β1 and Mcp‐1, VNH/VS, inflammation, and fibrosis.

The one-step synthesis of a polyester family containing dihydroxyacetone is described along with a quantitative analysis of in vitro/in vivo degradation kinetics and initial biocompatibility. Polyesters were synthesized by combining dihydroxyacetone, which is a diol found in the eukaryotic glucose metabolic pathway, with even-carbon aliphatic diacids (adipic, suberic, sebacic) represented in the long-chain alpha carboxylic acid metabolic pathway, by Schӧtten-Baumann acylation. We show that by using a crystalline monomeric form of dihydroxyacetone, well-defined polyesters can be formed in one step without protection and deprotection strategies. Both diacid length and polyester molecular weight were varied to influence polymer physical and thermal properties. Polyesters were generated with number-averaged (Mn) molecular weights ranging from 2200-11,500. Polydispersities were consistent with step-growth polymerization and ranged from 2 to 2.6. The melting (Tm) and recrystallization (Tc) temperatures were impacted in an unpredictable manner. Thermal transitions for the polyesters were highest for the adipic acid followed by suberic acid and sebacic acid, respectively. It was shown that the thermal response of the DHA-based polyesters was influenced by both the diacid length and molecular weight. In vitro degradation studies revealed first-order weight loss kinetics, the molecular weight loss followed first order kinetics with 25%-40% of the original mass remaining after 8 weeks. In vivo testing over 16 weeks highlighted that mass loss ranged from ∼70% to ∼6% depending upon initial molecular weight and diacid length. Histological analysis revealed rapid resolution of both acute and chronic inflammatory responses, normal foreign body responses were observed and no inflammation was present after week 4. This one-step synthesis proved robust with unique copolymers warranting further study as potential biomaterials.

A diverse range of clinical infections are on the increase, resulting in part from disruption of the natural microbiome, or even mycobiome, as a result of many different medical interventions. Amphotericin B (AmB) is a leading drug for the treatment of clinical fungal infections. However, AmB is extremely cytotoxic to mammalian cells, making use of the drug problematic. In this work, a drug delivery system made of polymerized cyclodextrin (pCD) allows for the localized administration of AmB, reducing the toxicity to host cells while retaining antifungal activity. A slow, sustained delivery rate of AmB was achieved through exploiting molecular interactions between the CD pockets and the drug. Surface plasmon resonance (SPR) and Fourier transform infrared spectroscopy (FTIR) were used to characterize the interaction between AmB and cyclodextrins (CDs). Through these methods, it was found that amphotericin binds strongly ([Formula: see text]M−1) to β-cyclodextrin. Release studies showed slow, sustained release of AmB from pCD disks. Antifungal activity was tested against Saccharomyces cerevisiae in assays for zone of inhibition, contact killing, and solution killing. In all assays, AmB-loaded pCD disks were found to exhibit significant antifungal activity. These results indicate that AmB-loaded pCD disks are capable of both the prevention of fungal growth and the elimination of established colonies. Additionally, results suggest that AmB exhibits antifungal activity whether associated with or released from pCD. The usage of pCD as a delivery vehicle also significantly reduces the toxic side effects of AmB, as seen in mammalian cell culture studies. These results show that in addition to reducing side-effects from systemic dosing, local delivery of AmB from pCD disks has the potential to improve its usage both in antifungal efficacy and reduced mammalian cell toxicity. Impact statement Amphotericin B (AmB) is an effective and commonly used antifungal agent. However, nephrotoxicity and poor solubility limits its usage. The proposed polymerized cyclodextrin (pCD) system therefore is an attractive method for AmB delivery, as it retains the antifungal activity of AmB while decreasing toxicity, and confining drug release to the local environment. This system could potentially be used for both prevention and treatment of established fungal infections, as AmB is toxic to fungus whether associated or released from pCD.