Structural and pharmacological characterization of phenylalanine-based AMPA receptor antagonists at kainate receptors

Continued efforts into the discovery of ligands that target ionotropic glutamate receptors (iGluRs) are important for studies of the physiological roles of the various iGluR subtypes as well as for the search for drugs that can be used in the treatment of diseases of the central nervous system. A new series of phenylalanine derivatives that target iGluRs was reported to bind AMPA receptors. Herein we report our studies of these compounds at the kainate receptors GluK1-3. Several compounds bind with micromolar affinity at GluK1 and GluK3, but do not bind GluK2. The crystal structure of the most potent compound in the ligand binding domain of GluK1 revealed different modes of binding to GluK1 and GluA2, due primarily to residues Ser741 (GluK1) and Met729 (GluA2). The compound was shown to be slightly more potent at GluK1 than at AMPA receptors and to induce a domain closure similar to that observed in GluK1 structures with partial agonists.     

Impact of Selected Chemical Characteristics of Cold-Pressed Oils on their Oxidative Stability Determined Using the Rancimat and Pressure Differential Scanning Calorimetry Method

In this study, 27 market and edible cold-pressed oils from 10 different oilseeds were analysed. Oxidative stability and the chemical composition of oils were evaluated. The oils were investigated for their primary quality, fatty acid composition, total phenolic content and antioxidant activity. Rancimat and pressure differential scanning calorimetry (PDSC) were used to assess oils oxidative stability. Principal component analysis (PCA) was conducted to determinate impact of selected chemical characteristics on tested oils’ oxidative stability in accelerated modes. PCA indicated that none of the chemical compounds correlated strongly with the oils’ oxidative stability determined by the Rancimat method. Correlation coefficients describing the impact of different chemical compounds on induction time determined using the Rancimat method were between r = ?0.54 (C18:3) to r = 0.62 (chlorophyll pigments). Oxidative stability of oils determined using the Rancimat and pressure differential scanning calorimetry (PDSC) were characterised by low correlation (r = 0.66). According to the statistical analyses, oils were divided into four groups, which depend on the method of oxidative stability evaluation did not differ.     

Modification of Multiresidue QuEChERS Protocol to Minimize Matrix Effect and Improve Recoveries for Determination of Pesticide Residues in Dried Herbs Followed by GC-MS/MS

An accurate, rapid, and reliable multiresidue QuEChERS method based on gas chromatography coupled with tandem mass spectrometry was developed for the determination of 235 pesticides in challenging, dry, complex herb matrices (Centaurea cyanus L., Matricaria chamomilla L., Thymus vulgaris L.). Sample mass and the type of cleanup sorbent used to estimate the procedure’s effectiveness were optimized. Purification steps with ChloroFiltr, ENVI-Carb, GCB, octadecyl, PSA, and Z-Sep as cleanup sorbents and a step without purification were compared. To minimize the matrix effect and obtain acceptable recoveries for pesticides, 2 g of herb sample and 10 mL acetonitrile, followed by d-SPE cleanup step with a combination of 150 mg PSA/45 mg ENVI-Carb/900 mg MgSO₄, and additionally 50 μL of 5% formic acid and some droplets of dodecane, were needed. Matrix effects for the vast majority of pesticides were reduced (>?20%), showing suppression or enhancement. Most recoveries were in the range of 70–120% (RSD < 18%), reaching the quantification limit of 0.001 to 0.002 mg kg^?1. There was excellent linearity within the range from 0.001 to 2.00 μg mL^?1, and a correlation coefficient higher than 0.999 was obtained. Expanded measurement uncertainty was estimated to be between 4 and 43%. Finally, the developed method was successfully employed to identify and quantify pesticide residues in the analysis of 46 real herb samples.     

Molecular pincers: antibody-based homogeneous protein sensors

We describe here a new homogeneous antibody-based protein sensor design (molecular pincers) that allows rapid and sensitive detection of a specific protein in solution. In the presence of the target protein these sensors produce fluorescence signal derived from target-dependent annealing of short complementary fluorochrome-labeled oligonucleotides attached to a pair of target-specific antibodies via nanometer-scale flexible linkers. The sensors allow near-instantaneous detection of the target with sensitivity and specificity approaching that of enzyme-linked immunosorbent assay (ELISA) but requiring no sample manipulation other then the addition of the sample to the sensor mix. We used cardiac troponin I and C-reactive protein as the targets to validate these desirable properties of the sensors. Due to the availability of antibodies to thousands of interesting targets and the straightforward design blueprint of the sensors we expect their wide-ranging applications in research and medical diagnosis, especially when simplicity, high throughput, and short detection time are essential.     

Effect of lecithin concentration on properties of sucrose-free chocolate masses sweetened with isomalt

Rheological properties such as Casson viscosity and yield value strongly affect costs and efficiency of the chocolate making process. The addition of a proper amount of lecithin to the blend of chocolate ingredients results in a decrease of both the aforementioned parameters. However, overdosing of lecithin leads to worse sensory attributes and flow properties of the chocolate mass. Our studies on rheological properties of isomalt-containing dark chocolate masses and sucrose-containing milk chocolate masses revealed that the critical lecithin concentration was 0.9 g/100 g; and the Casson yield value of both the types of chocolate blends was enhanced above this content. The same phenomenon, i.e. chocolate thickening, was observed at lecithin concentrations of 0.4 g/100 g and 0.6 g/100 g for milk chocolate masses sweetened with isomalt, and for dark chocolate masses sweetened with sucrose, respectively.     

Extra‐virgin and refined olive oils decrease plasma triglyceride,moderately affect lipoprotein oxidation susceptibility and increase bone density in growing pigs

The objective of this study was to determine the health benefits of extra‐virgin and refined olive oils, which are high in mono‐unsaturated fatty acids (MUFAs) and polyphenolic compounds using the pig as a model. Thirty‐two cross‐bred pigs were individually penned, allocated to one of four dietary treatments and fed ad libitum for 28 days. Two of the experimental diets consisted of a basal diet containing 12% tallow and either 7% sunflower oil (TSO) or 7% extra‐virgin olive oil (TEVO) on a w/w basis. The remaining diets contained 19% extra‐virgin olive oil (EVO) or 19% of refined olive oil (RO). On days 7, 14 and 28 fasted and 3‐h post‐prandial blood samples were taken. Body composition was measured at the beginning and end of the study using dual energy X‐ray absorptiometry. Daily gain, feed intake and lean and fat deposition were not significantly different between the treatments. However, the daily increase in bone mineral density was higher in pigs fed diets containing olive oil (1.23 vs 2.54, 6.28, 5.20 mg cm^?2 per day for TSO, TEVO, EVO and RO, respectively, P = 0.050). Both fasting and non‐fasting plasma triglycerides were lower (P = 0.003) in pigs fed MUFA‐rich diets, while the cholesterol profile was not significantly different between the treatments. The results from in vitro copper‐induced lipid peroxidation, expressed in terms of conjugated dienes, showed that low density lipoprotein (LDL) particles in postprandial serum from pigs fed olive oil were moderately more resistant to oxidative modification. In conclusion, these data demonstrate that both extra‐virgin and refined olive oils attenuate postprandial hypertriglyceridaemia, moderately affect oxidation susceptibility and increase bone mineral density in growing pigs. Copyright © 2006 Society of Chemical Industry     

Electric properties of monophase polycrystalline sinters SiC, B4C, TiC and their composites as non-inductive volume resistors

Monophase polycrystalline SiC, B₄C, TiC and their SiC-TiC, SiC-B₄C composite sinters with a theoretical density of 97% are characterized by good mechanical and thermal durability as well as a wide range of electrical conductivity values. SiC, which has semiconductor conductivity and negative TCR, was combined with TiC, which has metallic conductivity and positive TCR. Produced in this way resistive elements, within a temperature range from 293 K to 348 K, exhibit a TCR close to zero, and an impedance independent of frequency within a range from 100 Hz to 1 MHz. The combination SiC with 40 wt% of B₄C has been produced resistive elements, which are resistive to oxidation. This combination has also completly resistive character, within a range of 100 Hz to 1 MHz. Most of the investigated materials are suitable for high temperature, noninductive volume resistors.     

The effect of muscle, cooking method and final internal temperature on quality parameters of beef roast

The aim of the study was to evaluate the influence of cooking conditions (dry air and steam) and final internal temperature (75, 85, 95°C) on the physico-chemical properties of beef infraspinatus (INF) and semimembranosus (SEM) muscles as well as their tenderness and juiciness. Cooking method and temperature influenced moisture, total collagen content in cooked meat and cooking loss, whereas muscle type affected fat, total collagen content and cooking loss. Warner-Bratzler shear force values were affected by cooking method, which also influenced juiciness of roasts. Temperature affected tenderness and juiciness, whereas muscle type influenced juiciness. The most desirable tenderness had INF heated in steam and dry air to 95°C. Processing SEM in dry air to 85 and 95°C lowered the juiciness of the roasts. There were significant correlations between physico-chemical, sensorial and image attributes, however high accuracy of prediction (r(2)>0.8) was achieved only for SEM muscle.     

Protein degradation in bovine milk caused by Streptococcus agalactiae

Streptococcus (Str.) agalactiae is a contagious mastitis bacterium, often associated with cases of subclinical mastitis. Different mastitis bacteria have been evaluated previously from a diagnostic point of view, but there is a lack of knowledge concerning their effect on milk composition. Protein composition is important in achieving optimal yield and texture when milk is processed to fermented products, such as cheese and yoghurt, and is thus of great economic value. The aim of this in vitro study was to evaluate protein degradation mainly caused by exogenous proteases originating from naturally occurring Str. agalactiae. The samples were incubated at 37°C to imitate degradation caused by the bacteria in the udder. Protein degradation caused by different strains of Str. agalactiae was also investigated. Protein degradation was observed to occur when Str. agalactiae was added to milk, but there were variations between strains of the bacteria. Caseins, the most economically important proteins in milk, were degraded up to 75% in milk inoculated with Str. agalactiae in relation to sterile ultra-high temperature (UHT) milk, used as control milk. The major whey proteins, α-lactalbumin and β-lactoglobulin, were degraded up to 21% in relation to the sterile control milk. These results suggest that different mastitis bacteria but also different strains of mastitis bacteria should be evaluated from a milk quality perspective to gain knowledge about their ability to degrade the economically important proteins in milk.