Targeting Insulin-Degrading Enzyme in Insulin Clearance

Hepatic insulin clearance, a physiological process that in response to nutritional cues clears ~50–80% of circulating insulin, is emerging as an important factor in our understanding of the pathogenesis of type 2 diabetes mellitus (T2DM). Insulin-degrading enzyme (IDE) is a highly conserved Zn²⁺-metalloprotease that degrades insulin and several other intermediate-size peptides. Both, insulin clearance and IDE activity are reduced in diabetic patients, albeit the cause-effect relationship in humans remains unproven. Because historically IDE has been proposed as the main enzyme involved in insulin degradation, efforts in the development of IDE inhibitors as therapeutics in diabetic patients has attracted attention during the last decades. In this review, we retrace the path from Mirsky’s seminal discovery of IDE to the present, highlighting the pros and cons of the development of IDE inhibitors as a pharmacological approach to treating diabetic patients.     

Hydroxypyridinethione Inhibitors of Human Insulin-Degrading Enzyme

Insulin-degrading enzyme (IDE) is a human mononuclear Zn²⁺-dependent metalloenzyme that is widely regarded as the primary peptidase responsible for insulin degradation. Despite its name, IDE is also critically involved in the hydrolysis of several other disparate peptide hormones, including glucagon, amylin, and the amyloid β-protein. As such, the study of IDE inhibition is highly relevant to deciphering the role of IDE in conditions such as type-2 diabetes mellitus and Alzheimer disease. There have been few reported IDE inhibitors, and of these, inhibitors that directly target the active-site Zn²⁺ ion have yet to be fully explored. In an effort to discover new, zinc-targeting inhibitors of IDE, a library of ∼350 metal-binding pharmacophores was screened against IDE, resulting in the identification of 1-hydroxypyridine-2-thione (1,2-HOPTO) as an effective Zn²⁺-binding scaffold. Screening a focused library of HOPTO compounds identified 3-sulfonamide derivatives of 1,2-HOPTO as inhibitors of IDE (K_i values of ∼50 μM). Further structure-activity relationship studies yielded several thiophene-sulfonamide HOPTO derivatives with good, broad-spectrum activity against IDE that have the potential to be useful pharmacological tools for future studies of IDE.     

Ingredients and pH are Key to Clear Beverages that Contain Whey Protein

ABSTRACT:  A challenge of shelf stable beverages that contain whey protein is that a small portion of protein can be denatured and aggregated during thermal processing, resulting in a turbid solution or white precipitate that consumers perceive as a defect. In this study, 3 approaches were taken to reduce turbidity in heat-treated beverages that contain whey protein: (1) centrifugation to remove insoluble protein aggregates, (2) addition of ingredients, and (3) alteration of pH in the range from 3.0 to 4.0. At pH 3.6 and below, all samples were essentially clear both before and after heating for all ingredients. At a pH of 3.8 and above, ingredient selection was crucial to solution clarity after heat treatment. At a pH of 4.0, addition of salts at both 10 and 50 mM increased the turbidity significantly compared to the control, which contained only whey protein in water. Neither addition of sugars at 25, 50, and 100 g/L, nor addition of sugar alcohols at 25 g/L significantly affected turbidity after heat treatment compared to the control. However, sugar alcohols added at 50 or 100 g/L significantly reduced turbidity after heat treatment compared to the control. Removal of insoluble protein aggregates by centrifugation prior to heat treatment resulted in a statistically significant decrease in turbidity after heat treatment. Understanding these results at the molecular level will assist food scientists in selecting processing treatments, ingredients, and pH in the development of shelf stable clear beverages that contain whey protein.     

What Is the Role of HLA-I on Cancer Derived Extracellular Vesicles? Defining the Challenges in Characterisation and Potential Uses of This Ligandome

The Human Leukocyte Antigen class I (HLA-I) system is an essential part of the immune system that is fundamental to the successful activation of cytotoxic lymphocytes, and an effective subsequent immune attack against both pathogen-infected and cancer cells. The importance of cytotoxic T cell activity and ability to detect foreign cancer-related antigenic peptides has recently been highlighted by the successful application of monoclonal antibody-based checkpoint inhibitors as novel immune therapies. Thus, there is an increased interest in fully characterising the repertoire of peptides that are being presented to cytotoxic CD8+ T cells by cancer cells. However, HLA-I is also known to be present on the surface of extracellular vesicles, which are released by most if not all cancer cells. Whilst the peptide ligandome presented by cell surface HLA class I molecules on cancer cells has been studied extensively, the ligandome of extracellular vesicles remains relatively poorly defined. Here, we will describe the current understanding of the HLA-I peptide ligandome and its role on cancer-derived extracellular vesicles, and evaluate the aspects of the system that have the potential to advance immune-based therapeutic approaches for the effective treatment of cancer.     

In vitro release studies on matrix type transdermal drug delivery systems of naltrexone and its acetyl prodrug

Matrix type acrylic adhesive transdermal patches of naltrexone (NTX) and its 3-O-acetyl ester prodrug were prepared and evaluated for drug content, thickness, and in vitro release characteristics. Among the four DURO-TAK adhesive polymers (87-2516, 87-2054, 87-2501, and 87-2582) tested, 87-2516 proved to be the most suitable and compatible polymer for the transdermal delivery of NTX from NTX and prodrug patches. A linear relationship was observed for release flux (F) and cumulative amount (Mt) values versus 1%, 2%, and 3% drug loading at equimolar levels. The release of NTX from the patches showed a good correlation (R2>0.99) for Mt vs. square root t profiles, indicating that a Higuchian matrix diffusion mechanism of drug release from the transdermal adhesive patches was obtained. Overall, the amounts of NTX released from the prodrug patches were significantly higher than from the NTX patches, at all three drug loading levels.     

Hybrid fibers containing protein-templated nanomaterials and biologically active components as antibacterial materials

The persistent and emerging threat of bacterial infections now extends to many real world scenarios that drive a requirement for antimicrobial fabrics. Such functionalized textiles may find application in protective wear for medical and military personnel and provide functional wound dressings that reduce infection in situ. In this work, biomimetic enzyme entrapment and protein-directed nanomaterials synthesis is combined and applied to the antimicrobial functionalization of fabrics. A multi-faceted approach was adopted to address the fabrication of textiles with Ag nanoparticles, bactericidal proteins and mineral coatings that may contribute (singularly or in unison) to provide antimicrobial activity. Fibroin coordinated silver ions, for example, were chemically reduced to generate silver nanoparticles within the interior of silk fabric fibers. Silk textiles were further functionalized by the surface adsorption of the bactericidal enzyme lysozyme. The exposure of such lysozyme-conjugated fabrics to mineralizing solutions enabled the self-directed immobilization of the enzyme in a subsequent protective matrix of amorphous silica or titania. Silk-immobilized lysozyme was also utilized to adsorb nanocrystalline TiO₂ from solution onto the fabric surface; a subsequent layer of enzyme served to entrap the ceramic particles under a layer of biomimetically mineralized titania. The multiplicity of antimicrobial activities derived from this approach thereby combined; 1) the hydrolytic activity of lysozyme (demonstrated by radial diffusion assays), 2) the bactericidal properties of silver nanoparticles (demonstrated effective against Staphylococcus aureus, Escherichia coli, and silver resistant E. coli) and 3) the photocatalytic bactericidal response of TiO₂ under UV illumination.     

Assessing drought-induced change in a piñon-juniper woodland with Landsat: a multiple endmember spectral mixture analysis approach

Piñon-juniper communities exist on mid-elevation mountain ranges throughout the Southwestern USA. These species are drought adapted, and have lived with climatic stochasticity since the end of the Pleistocene. Rising temperatures and drought within the past two decades have stressed much of this community beyond its adaptive limits. With increased drought-induced stress, piñon show greater vulnerability to die-off than juniper. Widespread piñon die-off occurred from extreme drought in northern New Mexico (2002–2004) with minimal juniper die-off. This study assessed the feasibility of quantifying differential piñon and juniper mortality following a recent drought at a site in central New Mexico by performing multiple endmember spectral mixture analysis on six Landsat images from 2009 through 2015 using field-based spectra collected throughout 2015. An ideal spectral separability time of year was identified to maximize separation between constituent land-cover classes by calculating vegetation indices for the five dominant land-cover classes at the site (juniper, piñon, dead piñon, herbaceous, and soil). Ideal separability periods were also determined by evaluating precipitation and temperature data. Peak separabililty between land-cover classes within the study period was determined to occur during the pre-monsoon season between late spring/early summer (May) when minimal spectral overlap occurred between classes (σ = 1). The field-based spectra were then used to unmix each image in the study period. Results indicate a 24.6% decline of piñon across the study period with a comparable 23.8% increase of dead piñon. Accuracy assessment using high spatial (5–8 cm) resolution imagery for 2014 and 2015 showed strong correlation with modelled fractional cover results for 2014: live piñon and juniper (R² = 0.72), and dead piñon (R² = 0.79), and 2015: live piñon and juniper (R² = 0.77), dead piñon (R² = 0.65). Results demonstrate the potential of MESMA to monitor and accurately quantify the differential die-off of piñon and juniper at a regional scale as climate change-induced drought and higher temperatures are projected to continue in the Southwest.     

The influence of product knowledge on the relative importance of extrinsic product attributes of wine

The purpose of this paper is to examine the influence of product knowledge, both subjective and objective, on the relative importance of four extrinsic product attributes of wine, namely price, age, brand and region of origin. The relative importance of four product attributes is evaluated comparative to consumers’ self-reported and objectively measured knowledge of wine, using the conjoint analysis technique. The results suggest that product knowledge does influence the relative importance of extrinsic wine attributes in product evaluation, with the price of wine shown to be the dominant attribute regardless of the level of product knowledge expertise. Brand, age and region of origin received differing rankings of importance. Across all four levels of product knowledge, consumers navigate their evaluative product decisions according to the midpoint between most and least expensive wines in their consideration set. Price sensitivity appears to heavily impact consumer evaluation strategies, which serves to inform wine pricing strategies.