Excretion profile of glycyrrhizin metabolite in human urine

Glycyrrhizin is the main pharmacologically active component in licorice. Long term consumption of higher amounts of glycyrrhizin results in serious side effects (pseudoaldosteronism) caused by the glycyrrhizin metabolite 3β-monoglucuronyl-18β-glycyrrhetinic acid (3-MGA). The aim of this study was to determine urine excretion profile of 3-MGA. Six healthy volunteers ingested 600 mg of glycyrrhizin. In the first experimental period, glycyrrhizin was ingested in the morning and in the second experimental period, which followed after 2 weeks, glycyrrhizin was ingested in the evening. Results showed that the amount of excreted 18-MGA in urine was 1425.9-3147.8 μg, which corresponds to 0.31-0.67% of the ingested dose. Maximum elimination rates were 31.52-209.47 μg/h. There were no significant differences in the amount of excreted 3-MGA as well as in elimination rates of 3-MGA when glycyrrhizin was ingested in the morning or evening, respectively. These results provide some important clinical data on glycyrrhizin metabolism.     

Comparison of isolation methods for the determination of buckwheat volatile compounds

Five different isolation techniques were combined with gas chromatographic–mass spectrometric determination of aroma compounds from buckwheat: dynamic headspace (DHS) with cryotrapping or sorbent trapping, solid-phase microextraction (SPME), headspace sorptive extraction (HSSE), solvent extraction (SE) and simultaneous distillation–extraction (SDE). Optimisation of each technique is presented, as well as comparison of the chemical profiles obtained by them. Solvent extraction with methanol resulted in the isolation of rather polar and less volatile compounds and was deemed least suitable for the odour-active compounds. Only SPME with DVB/CAR/PDMS fibre was suitable for the isolation of highly volatile compounds in a wider polarity range. DHS extracted the smallest number of compounds, but with the comparable chemical profile as obtained by SDE, which was chosen as the most suitable technique to obtain the aroma compounds of cooked buckwheat. The applied isolation techniques are complementary in their ability to extract a representative aroma profile of buckwheat.     

On the Role of Curved Membrane Nanodomains and Passive and Active Skeleton Forces in the Determination of Cell Shape and Membrane Budding

Biological membranes are composed of isotropic and anisotropic curved nanodomains. Anisotropic membrane components, such as Bin/Amphiphysin/Rvs (BAR) superfamily protein domains, could trigger/facilitate the growth of membrane tubular protrusions, while isotropic curved nanodomains may induce undulated (necklace-like) membrane protrusions. We review the role of isotropic and anisotropic membrane nanodomains in stability of tubular and undulated membrane structures generated or stabilized by cyto- or membrane-skeleton. We also describe the theory of spontaneous self-assembly of isotropic curved membrane nanodomains and derive the critical concentration above which the spontaneous necklace-like membrane protrusion growth is favorable. We show that the actin cytoskeleton growth inside the vesicle or cell can change its equilibrium shape, induce higher degree of segregation of membrane nanodomains or even alter the average orientation angle of anisotropic nanodomains such as BAR domains. These effects may indicate whether the actin cytoskeleton role is only to stabilize membrane protrusions or to generate them by stretching the vesicle membrane. Furthermore, we demonstrate that by taking into account the in-plane orientational ordering of anisotropic membrane nanodomains, direct interactions between them and the extrinsic (deviatoric) curvature elasticity, it is possible to explain the experimentally observed stability of oblate (discocyte) shapes of red blood cells in a broad interval of cell reduced volume. Finally, we present results of numerical calculations and Monte-Carlo simulations which indicate that the active forces of membrane skeleton and cytoskeleton applied to plasma membrane may considerably influence cell shape and membrane budding.     

The state of several indices of non-specific immunity in rats with nephrotoxic glomerulonephritis

Changes in the interferon reaction of leukocytes, bactericidal property of the blood serum against the E. coli and streptococcus, the activity of beta-lysins in experimental nephrotoxic glomerulonephritis reproducible with the aid of heterogenous nephrotoxic serum in mongrel male rats were studied. This model permitted to trace the changes in the nonspecific protection mechanisms depending on the pathological process in the kidneys. In nephrotoxic glomerulonephritis the most pronounced changes were seen in the interferon reaction of leukocytes: it decreased up to 90% in comparison with the normal depending on the duration of the disease. In difference from this the changes in the anti-bacterial immunity indices were observed at the period of marked nephrotic process activity.     

可靠性和维修性——现代设计的关键因素（一）

提高利润的压力迫使管理人员不得不改进技术以降低资产管理成本,这改变了维修人员和维修操作的地位。日益复杂的技术系统、公众对产品质量的要求以及关于产品责任的新法律等也进一步推进了可靠性和维修性的发展。本文描述了可靠性和维修性在总体设计中的地位以及其对寿命周期费用和总体设备效率的影响,列举了一些实际可行的可靠性和维修性的评估方法,并给出了一些实例。最后简单地介绍了一些系统方法在斯洛文尼亚“早期设备管理”领域的基本运用和早期成果。     

Identification,in vitro and in vivo Antioxidant Activity,and Gastrointestinal Stability of Lignans from Silver Fir (Abies alba) Wood Extract

Lignans are generally known for their beneficial impact on human health. In this study, we found that the water extract of silver fir (Abies alba) wood contains lignans, which constitute approximately 10% of the extract and include isolariciresinol, hydroxymatairesinol, secoisolariciresinol, lariciresinol, pinoresinol, and matairesinol. The antioxidant activity of the extract was measured by several in vitro assays and an assay in a eukaryotic cell model (yeast). The extract had greater in vitro antioxidative activity than ascorbic acid, resveratrol, or butylated hydroxytoluene (BHT) and similar antioxidative activity to epigallocatechin gallate. The intracellular antioxidant effect in the yeast gave indirect evidence that the components of the silver fir wood extract (SFWE) effectively pass through eukaryotic cell membranes and have higher in vivo antioxidative activity than ascorbic acid, resveratrol, tocopheryl succinate, or BHT and similar to epigallocatechin gallate. The in vitro gastrointestinal digestion of the lignans in the extract is not significant; therefore, it is reasonable to expect antioxidative effects from orally applied SFWE.     

Opioid Receptors and Protonation-Coupled Binding of Opioid Drugs

Opioid receptors are G-protein-coupled receptors (GPCRs) part of cell signaling paths of direct interest to treat pain. Pain may associate with inflamed tissue characterized by acidic pH. The potentially low pH at tissue targeted by opioid drugs in pain management could impact drug binding to the opioid receptor, because opioid drugs typically have a protonated amino group that contributes to receptor binding, and the functioning of GPCRs may involve protonation change. In this review, we discuss the relationship between structure, function, and dynamics of opioid receptors from the perspective of the usefulness of computational studies to evaluate protonation-coupled opioid-receptor interactions.     

Antimony powder-modified carbon paste electrodes for electrochemical stripping determination of trace heavy metals

A new type of the antimony electrode based on a carbon paste bulk-modified with antimony powder (Sb-CPE) is presented for the determination of cadmium(II) and lead(II) ions at the microgram-per-liter concentration level, when using square-wave anodic stripping voltammetric or stripping chronopotentiometric protocol. The Sb-CPE was prepared by mixing fine antimony powder, carbon powder, and silicon oil, thus combining typical features of the carbon paste material with specific electrochemical properties of antimony. Key-operational parameters, including the amount of antimony powder in the carbon paste mixture, effect of the deposition potential and deposition time, were optimized and electroanalytical performance of the Sb-CPE in nondeaerated solution of 0.01 M hydrochloric acid (pH 2) was compared with related bismuth powder-modified carbon paste electrode (Bi-CPE) and with in situ prepared antimony film carbon paste electrode (SbF-CPE). The electrode of interest exhibited well-developed signals and highly linear calibration plots for both metal ions tested. In addition, favorable limits of detection were achieved; namely: 1.4 μg L⁻¹ for Cd(II) and 0.9 μg L⁻¹ for Pb(II). The applicability of the new electrode was demonstrated on the analysis of tap water (spiked sample). Besides voltammetric measurements, the Sb-CPE was preliminary tested also under chronopotentiometric stripping mode in deoxygenated solutions, revealing also an excellent electroanalytical performance.