Selenium in food and the human body: a review

Selenium levels in soil generally reflect its presence in food and the Se levels in human populations. Se food content is influenced by geographical location, seasonal changes, protein content and food processing. Periodic monitoring of Se levels in soil and food is necessary. Diet is the major Se source and approximately 80% of dietary Se is absorbed depending on the type of food consumed. Se bioavailability varies according to the Se source and nutritional status of the subject, being significantly higher for organic forms of Se. Se supplements can be beneficial for subjects living in regions with very low environmental levels of Se. Several strategies have been followed: (1) employment of Se-enriched fertilizers; (2) supplementation of farm animals with Se; (3) consumption of multimicronutrient supplements with Se. Nevertheless, detailed investigations of possible interactions between Se supplements and other food components and their influence on Se bioavailability are needed. Suppliers also need to provide more information on the specific type of Se used in supplements. In addition, research is lacking on the mechanisms through which Se is involved in hepatocyte damage during hepatopathies. Although Se potential as an antioxidant for the prevention of cardiovascular diseases (CVD) is promising, additional long-term intervention trials are necessary. As a result, indiscriminate Se supplements cannot be reliably recommended for the prevention of CVD in human beings. Some interesting findings reported an association of Se intake with a reduced prevalence and risk for prostate and colon cancer. However, random trials for other cancer types are inconclusive. As a final conclusion, the general population should be warned against the employment of Se supplements for prevention of hepatopathies, cardiovascular or cancer diseases, because benefits of Se supplementation are still uncertain, and their indiscriminate use could generate an increased risk of Se toxicity.     

Non-linear impedance characterization of blood cells-derived microparticle biomarkers suspensions

This paper examines the application of higher harmonic Non-Linear Electrochemical Impedance Spectroscopy (NLEIS) to characterization of colloidal suspensions of clinically relevant microparticle biomarkers derived from monocytes (white blood cells). This study expands on previous linear EIS investigations of microparticle biomarkers’ suspensions and NLEIS studies of non-aqueous colloidal systems. Numerical minimization analysis allowed to develop a more accurate equivalent circuit model for the low frequency region (<1 kHz) and provided qualitative insight into the kinetic and physiological parameters of the system. The developed NLEIS characterization method permitted to resolve several remaining ambiguities in interpretation of low-frequency linear impedance experimental results for microparticles’ suspensions. These results support continued development of the NLEIS method validation and instrumentation for microparticle biomarkers’ analysis, further expanding its clinical diagnostic capabilities.     

苏北盆地高邮凹陷泰州组瓦6井油源对比

高邮凹陷发现的油藏原油来自泰二段烃源岩的较少,仅瓦6井的原油可能来自泰二段烃源岩。通过对泰二段烃源岩,尤其对马5井,与瓦6井泰一段原油的地球化学特征进行对比分析,发现瓦6井原油Pr/Ph<1Pr/nC₁₇18,C_27,C₂₈, C₂₉呈倒三角形,即C₂₈最低,C₂₉最高,与泰二段烃源岩特征相似;另外,瓦6井原油的饱和烃色谱、萜烷及甾烷图谱等与泰二段烃源岩也呈现相同特征,但与阜宁组有明显区别。因此,分析认为瓦6井原油来自泰二段烃源岩,这一发现能为高邮凹陷泰州组油气提供新的勘探方向,具有一定的指导意义。     

Urinary biomarkers for assessing dietary exposure to caffeine

The feasibility of using metabolites specific to caffeine as urinary biomarkers to be employed in the estimation of dietary caffeine intake is reported. The influence of inter-individual differences in the metabolism of caffeine and the effect of volunteer phenotype on the interpretation of potential biomarkers has been investigated using urinary caffeine metabolite data. This method of phenotype determination accurately reflected the rate constant for the cytochrome P4501A2 (CYP1A2)-catalysed 3-demethylation of caffeine in vivo . Three studies with up to 20 human volunteers demonstrated that a 24-h urine collection after a caffeine dose allows quantification of the metabolites excreted; that the ratios of selected metabolites used to classify the volunteers into fast, intermediate or slow caffeine metabolizers by CYP1A2 phenotype gave a similar result (2:7:3, slow:intermediate:fast) to that found in the general population (1:7:2); and that three metabolites, 1,7-dimethylxanthine, 1,7-dimethyluric acid and 1-methylxanthine, could be studied further as potential biomarkers for caffeine dietary intake.     

The nature and consequence of vitronectin interaction in the non-compromised contact lens wearing eye

Purpose

The aim of this work was to investigate the locus and extent of vitronectin (Vn) deposition on ex vivo contact lenses and to determine the influence of wear modality together with surface and bulk characteristics of the lens material.

Early detection of food pathogens and food spoilage microorganisms: Application of metabolomics

BackgroundFood safety is a major issue, with a large number of people around the world suffering from illness due to the consumption of contaminated and unsafe food products. An early detection of food pathogens and spoilage microorganisms is an important step that can help to control a foodborne outbreak, thus avoiding the loss of a massive amount of food products.Scope and approachMetabolomics is generally a hypothesis generating tool that makes use of different analytical instruments to analyse as many metabolites as possible in a given biological sample. Metabolomics has already been successfully applied to different areas of food science. Here, I present metabolomics as a valuable tool for studying the metabolism of food pathogens and spoilage microorganisms.Key findings and conclusionsThe scientific area of metabolomics has improved tremendously over last decade. Due to the rapid development of instrumental platforms, it is now possible to analyse a wide range of metabolites present in food and produced by microorganisms. This approach has a high potential to determine biomarkers which can later be used for the development of early detection tools for food pathogens and spoilage microorganisms, thus ensuring a better management of food safety.     

Impacts of pollution in feral Mya arenaria populations: The effects of clam bed distance from the shore

This study examined the relationships between population characteristics and the expression of physiological biomarkers of stress in an intertidal clam population under pollution at sites differing in thermal history and coastline distance. The clam population metrics were age distribution, growth, condition factor, distance of the clam beds from the shore, and gonad development. Physiological biomarkers comprised biomarkers of defence such as superoxide dismutase, labile IIb metals in tissues, redox status of metallothioneins and glutathione S-transferase, of tissue damage such as lipid peroxidation and DNA strand breaks, of reproduction as determined by vitellogenin-like proteins and gonadosomatic index and immunocompetence such as phagocytosis and hemocyte viability. Age-related pigments were also examined to compare the physiological age of the clams with their chronological age. The results showed that all the above biomarkers were significantly affected at one of the two polluted sites at least. Distance from the shore was significantly correlated with most (81%) of the biomarkers examined. Clams collected at one polluted site were physiologically older than clams from the corresponding reference site. Canonical and adaptive regression (artificial neural networks) analyses found that the biomarkers measured in this study were able to predict the ecologically relevant endpoints. Biomarkers implicated in defense mechanisms, tissue damage and age-related pigments were most closely related to the clam population characteristics. Sensitivity analysis of the learning algorithm found that the following physiological and biochemical markers were the most predictive, in decreasing order, of clam population characteristics: glutathione S-transferase, phagocytosis, age pigments, lipid peroxidation in the gills, labile IIb metals and total MT levels. These biomarkers were affected by the distance of the clam beds from the shore, site quality (pollution) and reproduction activity.     

食源性致病沙门氏菌血清型生物标志物的研究

寻找食源性致病沙门氏菌(Salmonella)血清型生物标志物,是研发食源性致病微生物鉴定及监控技术的基础。本文基于代谢组学技术提取5种沙门氏菌血清型8株标准菌株胞内代谢产物,对各菌株进行胞内代谢轮廓分析,并构建指纹图谱和PCA分析。研究发现,各血清型之间的产物在种类和丰度上具有较大差异,其中肠炎沙门氏菌血清型的特异性产物为硫基乙酸和α-羟基-戊二酸,伤寒沙门氏菌血清型特有产物为N-乙酰基-天冬氨酸、2(1H)-嘧啶酮和L-苏糖酸,鼠伤寒沙门氏菌血清型特有产物为肉豆蔻酸甲酯和甘油醚葡萄糖苷,猪霍乱沙门氏菌血清型特有产物1,4-萘醌,亚利桑那沙门菌血清型特有产物为3-吡啶甲酸三甲酯;通过聚类分析和PCA分析可以明显区分这5种沙门氏菌血清型。因此以上特异性产物有望作为各自血清型的潜在生物标志物。