Very low C-reactive protein in apparently healthy individuals: physiological status or just a reflection of an improved health profile

The objective of our study was to determine whether the very low concentrations of C-reactive protein (CRP) detected by high-sensitivity CRP (hs-CRP) assays that one encounters from time to time in apparently healthy individual represent a physiological status or are just a reflection of an improved general health profile. The concentration of hs-CRP was determined by using the Behring BN II nephelometer. The arbitrary cut-off point of hs-CRP (≤0.16mgl^-1) was determined at the lower detection level of the assay. A total of 6588 apparently healthy individuals were screened following exclusion of recent infection/inflammation by using a detailed questionnaire. One hundred and sixty (2.4%) individuals out of the above-mentioned cohort presented hs-CRP concentrations of ≤0.16mgl^-1. They were found to be significantly younger and lean, had an improved lipid profile and an attenuated acute-phase response in terms of lower erythrocyte sedimentation rate and fibrinogen concentration as well as white blood cell count. In addition, these individuals had less atherothrombotic risk factors, except for smoking habits which were as frequent as in those of individuals with a higher hs-CRP concentration. After calculating the concentration of this biomarker following multiple adjustments, the individuals with very low CRP remained with a very low value despite the multiplicity of the adjustments. We raise the possibility that this particular low concentration might represent a physiological status and is not necessarily a result of the improved general health profile per se.     

An efficient callus proliferation protocol and rhaponticin accumulation of Rheum franzenbachii Munt., a medicinal plant

An efficient callus proliferation system for Rheum franzenbachii Munt., a rare medicinal plant, has been developed. Callus induced from leaf explants incubated on Murashige and Skoog (MS) medium with appropriate supplements of plant growth regulators. In the 6-benzylaminopurine (6-BAP) in combination with α-naphthalene acetic acid (NAA) treatments, different concentrations of NAA showed different induction effects on explants. When concentration of 6-BAP was as high as 2.0 mgl^?1 in combination with 0.5 mgl^?1 NAA, the callus induction rate reached 58.3%. N-phenyl-N’-1,2,3-thiadiazol-5-ylure (TDZ) in combination with NAA was very suitable for callus proliferation compared to TDZ in combination with 2,4-dicholorophenoxy acetic acid (2,4-D) or TDZ in combination with indole-3-acetic acid (IAA). Fresh and dry weight of callus cultured on MS medium supplemented with 0.5 mgl^?1 TDZ in combination with 0.2 mgl^?1 NAA increased 26.3 and 15.0 times within 35 days culture, respectively. Quantitative analysis of rhaponticin by HPLC showed that the phytochemical profile of callus was similar to that of wild plants, and the content of rhaponticin in callus cultured on MS medium supplemented with 0.5 mgl^?1 TDZ and 0.2 mgl^?1 NAA was 16.6 mgg?¹DW compared to that of 4.0 mgg^?1 DW in wild plants.     

N-monoarylacetothioureas as potent urease inhibitors: synthesis,SAR, and biological evaluation

Abstract

A urease inhibitor with good in vivo profile is considered as an alternative agent for treating infections caused by urease-producing bacteria such as Helicobacter pylori. Here, we report a series of N-monosubstituted thioureas, which act as effective urease inhibitors with very low cytotoxicity. One compound (b19) was evaluated in detail and shows promising features for further development as an agent to treat H. pylori caused diseases. Excellent values for the inhibition of b19 against both extracted urease and urease in intact cell were observed, which shows IC₅₀ values of 0.16?±?0.05 and 3.86?±?0.10?µM, being 170- and 44-fold more potent than the clinically used drug AHA, respectively. Docking simulations suggested that the monosubstituted thiourea moiety penetrates urea binding site. In addition, b19 is a rapid and reversible urease inhibitor, and displays nM affinity to urease with very slow dissociation (k _off=1.60?×?10^?3 s^?1) from the catalytic domain.     

Ethnic groups and high sensitivity C-reactive protein in Israel

Abstract

High-sensitivity C-reactive protein (hs-CRP) is a biomarker that correlates with atherothrombotic risk and outcome. hs-CRP is influenced by various modifiable and non-modifiable factors. We studied the relationship between ethnic background and hs-CRP level, among the Jewish population in Israel. A total of 3659 men and 2180 women were divided into two ethnic groups (Ashkenazi and Sephardic Jews), based on the knowledge of Jewish immigration patterns throughout the centuries. Mean hs-CRP levels were calculated for each group and were adjusted for various factors known to influence hs-CRP. Sephardic Jews were found to have higher adjusted mean hs-CRP levels (2.0 mg l^?1 for men and 3.9 mg l^?1 for women) compared with Ashkenazi Jews (1.5 mg l^?1 for men and 2.9 mg l^?1 for women). Ethnic background emerged as an independent significant predictor of hs-CRP levels. We demonstrated that ethnicity is an important factor when considering hs-CRP as a marker of atherothrombotic risk.     

The baseline levels and risk factors for high-sensitive C-reactive protein in Chinese healthy population

Background

Recent studies show that C-reactive protein (CRP) is not only a biomarker but also a pathogenic mediator contributing to the development of inflammation and ageing-related diseases. However, serum levels of CRP in the healthy ageing population remained unclear, which was investigated in the present study.

Methods

Serum levels of high sensitive C-reactive protein (hs-CRP), glucose (Glu), triglyceride (TG), cholesterol (CHOL), high-density lipoprotein cholesterol (HDL-c), low-density lipoprotein cholesterol (LDL-c), superoxide dismutase (SOD), serum creatinine (SCr), serum uric acid (SUA) were measured in 6060healthy subjects (3672 male and 2388 female, mean age:45.9 years) who received routine physical examination at Sun Yat-sen Memorial Hospital, Guangzhou, China.

Results

In total of 6060 healthy people, serum levels of hs-CRP were significantly increased with ageing (P?<?0.05), particularly in those with age over 45-year-old (1.31[0.69–2.75] vs 1.05[0.53–2.16]mg/L, P?<?0.001). Interestingly, levels of serum hs-CRP were significantly higher in male than female population (1.24[0.65–2.57] vs 1.07[0.53–2.29]mg/L, P?<?0.001). Correlation analysis also revealed that serum levels of hs-CRP positively correlated with age and SUA, but inversely correlated with serum levels of HDL-c and SOD (all P?<?0.05).

Conclusions

Baseline levels of serum hs-CRP are increased with ageing and are significantly higher in male than female healthy population. In addition, elevated serum levels of hs-CRP are also associated with increased SUA but decreased HDL-c and SOD. Thus, serum levels of hs-CRP may be an indicator associated with ageing in healthy Chinese population.

     

Epigallocatechin-3-gallate inhibits interleukin-6- and angiotensin II-induced production of C-reactive protein in vascular smooth muscle cells

AimsExtensive research suggests that atherosclerosis is an inflammatory disease and that epigallocatechin-3-gallate (EGCG) is able to inhibit the formation and development of atherosclerosis. However, the mechanisms of action of EGCG against atherosclerosis are still unclear. Therefore, the effect of EGCG on interleukin-6 (IL-6)- and angiotensin II (Ang II)-induced CRP production in vascular smooth muscle cells (VSMCs) was studied to provide experimental evidence for its anti-inflammatory and anti-atherosclerotic actions.Main methodsRat VSMCs were cultured, and IL-6 (10^? 7 M) and Ang II (10^? 7 M) were used as stimulants for CRP generation. The CRP concentration in the supernatant was measured with ELISA, and mRNA and protein expression of CRP was assayed with RT-qPCR and immunocytochemistry, respectively. The production of reactive oxygen species (ROS) and superoxide anion (O₂^?) was detected with ROS and O₂^? assay kits, respectively.Key findingsThe results showed that both IL-6 and Ang II increased CRP levels in the supernatant of VSMCs and induced mRNA and protein expression of CRP in VSMCs, whereas pretreatment of the cells with EGCG (1 × 10^? 6 M, 3 × 10^? 6 M, 10 × 10^? 6 M) significantly inhibited IL-6- and Ang II-induced production and expression of CRP in VSMCs in a concentration-dependent manner. Additionally, Ang II stimulated O₂^? and ROS generations in VSMCs, and EGCG decreased the Ang II-induced increase of O₂^? and ROS in a concentration-dependent fashion.SignificanceThese results suggest that EGCG plays an anti-inflammatory role via inhibiting IL-6- and Ang II-induced CRP secretion, as well as the Ang II-induced generation of O₂^? and ROS in VSMCs, which contributes to its anti-atherosclerotic action.     

The effects of hydrocarbon pollution from a two‐stroke outboard engine on the feeding behaviour of Lythrypnus dalli (Perciformes: Gobidae)

Feeding behaviour (time of attack on flake fish food) in Lythrypnus dalli was measured under pollution concentrations of 2.1 and 4.01mgl^?1 total extractable material produced by a two‐stroke outboard engine. The variance of the times increased in pollution versus control treatments for both concentrations. No significant difference was found between the mean times of the control and 2.1 mgl^?1 pollution treatments. A significant difference was found between the mean times of the control and pollution treatments for two different tests at 4.01 mgl^?1. The combination of the increase in mean time of food attack and the increase of variance indicates that pollution concentrations lower than LD50 levels change feeding behaviour, and thus may indirectly effect the survival of the organism.     

Is C-reactive protein elevated in obstructive sleep apnea? a systematic review and meta-analysis

Purpose: This study examined whether circulating C-reactive protein (CRP) is elevated in obstructive sleep apnoea (OSA) independent of the confounding effects of comorbidities, smoking, body mass index (BMI), age and gender.

Methods: A systematic review of the literature was performed using PubMed, Embase and Cochrane databases from 1 January 1997 to 1 November 2017 using the key words obstructive sleep apnoea and C-Reactive protein to identify full text English language studies that compared CRP in adult non-smoking OSA participants without comorbidities and adult healthy non-smoking control participants matched for BMI, age and gender. Data from eligible studies were subjected to meta-analysis using RevMan version 5.3.

Results: Five studies (219 OSA participants, 116 controls) met the selection criteria. The total standard mean difference for circulating high sensitivity CRP was 0.61?mg/dL higher in OSA participants than in control participants (confidence interval: 0.38 to 0.84, p?<?0.00001), with low between-studies heterogeneity (df = 7, p?=?0.16, I²?=?33%) and minimal evidence of publication bias.

Conclusions: CRP levels in non-smoking OSA participants without comorbidities were increased relative to levels in healthy matched non-smoking control participants, suggesting that pharyngeal or systemic inflammatory effects attributable to OSA may elevate CRP.     

Low C-Reactive Protein Levels in a Traditional West-African Population Living in a Malaria Endemic Area

Background

C-reactive protein (CRP) levels are reported to be elevated in populations of African descent living in affluent environments compared to populations of European ancestry. However, the natural history of CRP levels in populations of African descent living under adverse environments remains largely unknown.

Methods

CRP levels were measured with a high sensitivity assay in 624 apparently healthy individuals who contributed blood as part of a study on innate immune responsiveness in a traditional Ghanaian population living under adverse environmental conditions in a malaria endemic area. As a comparison, we included CRP measurements from 2931 apparently healthy individuals from the Dutch population that were included in the same batch of CRP analyses. Associations between CRP and body mass index (BMI), immune responsiveness, and P. falciparum parasitaemia were investigated.

Results

In an age- and sex-adjusted model, CRP levels were 0.54 mg/L lower in the Ghanaian compared to the Dutch cohort (1.52 vs. 0.98 mg/L, p<0.001). When accounting for the substantially higher average BMI in the Dutch compared to the Ghanaians (25.6 vs. 18.4 kg/m²) the difference in CRP levels disappeared. BMI associated positively with CRP in the Dutch but not in the Ghanaians. In individuals with an acute phase response, CRP levels were higher in the Ghanaian compared to the Dutch cohort (24.6 vs. 17.3 mg/L, p = 0.04). Levels of CRP were positively related to immune responsiveness and P. falciparum parasitaemia (all p<0.001) among Ghanaians.

Conclusions

Our study demonstrates that West-Africans do not exhibit an inherently high inflammatory state. The role of genes, environment and gene-environment interaction in explaining reports of elevated CRP levels in populations of African ancestry when compared to other ethnicities living in affluent environments thus merits further investigation.     

Improved methods for the measurement of dissolved and particulate organic carbon in fresh water and their application to chalk streams

The development and use of an improved automatic system for the accurate measurement of dissolved organic carbon (D.O.C.) in fresh waters is described. The method, which covers the range 0-25 mgl^?1 D.O.C., is based on the oxidation of organic carbon to carbon dioxide by U.V. radiation. The carbon dioxide produced is measured by a non dispersive infra-red gas analyser (I.R.G.A.). The I.R.G.A. is also used in the semi-automatic measurement of particulate organic carbon (P.O.C.) by a combustion method which allows very low concentrations to be measured using samples of 200 ml or less. Results of surveys of two river systems indicate that D.O.C. concentrations of less than 2.0 mg l^?1 are typical in unpolluted chalk streams. D.O.C. concentrations of streams draining acid heathland were found to be significantly higher (3-5.5 mg l^?1). D.O.C. concentration was found to increase rapidly during a spate, in a river draining areas of mixed underlying geology. The throughput of D.O.C. during the twenty-five to fifty spates which occur annually in the river could amount to 20-30% of the annual flux of D.O.C. P.O.C. concentration in chalk spring waters (0.03–0.04 mg l^?1) were found to be higher than expected from preliminary estimates using membrane filtration techniques. The relevance of the measurement of D.O.C. and P.O.C. flux to estimates of the energy budgets of stream ecosystems is discussed and published methods for the automatic measurement of D.O.C. are reviewed.     

Immobilization and mineralization of dissolved free amino acids by stream-bed biofilms

1. Radiolabelled (¹⁴C) amino acids were used to investigate the influence of sediment size as well as dissolved free amino acid (DFAA) concentration and composition on immobilization and mineralization of DFAAs by biofilms from a first-order stream. 2. Over time (240 min), biofilms on stony substrata immobilized a DFAA mixture more effectively than those on sandy substrata, however proportional mineralization of immobilized DFAAs was higher for sandy substrata (36 v 20%). 3. Using stony substrata, the DFAA mixture was immobilized more rapidly than glycine alone at ‘near-natural’ amino acid concentrations (c. 37 μgl^?1), as well as enriched concentrations (1 and 100 mg 1-^?1). Instantaneous rates of glycine immobilization and mineralization were not saturated at glycine enrichments of up to 980 mgl^?1. 4. With both the amino acid mixture and glycine alone, proportional mineralization of the immobilized amino acids increased on enrichment to Img 1-^?1 (DFAA mixture: from 25 to 37%; glycine alone: from 50 to 54%), but then fell on further enrichment to 100mgl^?1 (DFAA mixture: 11%; glycine alone: 7%). 5. Results are discussed in terms of the potential trophic utility of immobilized DFAAs as well as the apparent roles of biotic and abiotic immobilization mechanisms. Immobilization and mineralization responses to variables investigated in this study give an insight into potential variability of carbon immobilization and retention in stream-bed sediments. This is fundamental to an understanding of how DOC may become available to higher trophic levels.     

In vitro clonal propagation of dioecious Carica papaya

A procedure for in vitro propagation of dioecious papaya clones is described. A high rate of success in culture estbalishment was obtained when axillary buds were taken from lateral shoots of hedged rooted cuttings grown in a greenhouse. Seasonal endophytic contamination was suppressed by shaking propagules for 24 h in 300 mgl^-1 rifampicin or by incorporating it at 50 mgl^-1 into the medium. Murashige & Skoog (MS) basal medium supplemented with 0.5 mgl^-1 6-benzyladenine and 0.1 mgl^-1 naphthaleneacetic acid was used for establishment and proliferation. The addition of 160 mgl^-1 adenine sulfate improved multiplication and shoot growth. An elongation stage on MS medium supplemented with 1.0 mgl^-1 kinetin and 0.05 mgl^-1 naphthaleneacetic acid was necessary before rooting. Rooting was obtained at a high rate on half-strength macroelements of MS medium supplemented with 1.0 mgl^-1 indole-3-butyric acid. Commercial plots of papaya plants obtained through this procedure already exist.     

Simultaneous removal of phosphorus and nitrogen in sequencing batch reactor

In this research, investigations were made on material transfer mechanisms and optimum operation mode for sequencing batch reactor system removing phosphorus and nitrogen simultaneously. Phosphorus release characteristics were expressed in the Monod equation, in which the reaction rate was replaced with specific phosphorus release (SPR) rate. The rate of SPR was increased during the first 80 days, but increased sharply to reach 0.003 hr^-1 afterwards. Phosphorus removal efficiencies were about 60% in the first 80 days, 75% after 80 days, and above 95% after 120 days. After 120 days, phosphorus concentration in effluent was below 0.5 mgl^-1 when 8 mgl^-1 was in the influent and the released phosphorus after 3-hour-anaerobic period was 60 mgl^-1. In the proposed optimum operation strategy (2-hour anaerobic react, 3-hour aerobic react, 4-hour anoxic react, and 3-hour settle and draw), phosphorus reappeared if the oxidized nitrogen was completely denitrified. In order to prevent this undesirable phosphorus release, anoxic period should be reduced to the extent of which the minimal concentration of the oxidized nitrogen existed. Phosphorus removal efficiency was stable under shock load as 5 times high as normal phosphorus concentration.Abbreviations dP/dt Phosphorus release rate (mgl^-1 hr^-1) - K Phosphorus release yield constant (mg P mg TOC^-1) - dS/dt Substrate utilization rate (mgl^-1 hr^-1) - X Mixed liquor suspended solid (MLSS, mgl^-1) - S Soluble TOC (mgl^-1) - k-q_max (Y_max)^-1 Maximum substrate utilization rate - Y Yield coefficient (mg mg^-1) - K_s Saturation constant (mgl^-1) - P_max kK-Maximum phosphorus release rate (hr^-1) - P_rel Total released phosphorus (mgl^-1) - P_o Phosphorus in influent (mgl^-1) - P_e phosphorus in effluent (mgl^-1) - t Anaerobic period (hr)     

Selenium nano-particle induced alterations in expression patterns of heat shock factor A4A (HSFA4A), and high molecular weight glutenin subunit 1Bx (Glu-1Bx) and enhanced nitrate reductase activity in wheat (<Emphasis Type="Italic">Triticum aestivum</Emphasis> L.)

Taking account of heat shock factor A4A (HSFA4A) as a hydrogen peroxide sensor, anti-apoptosis agent, and crosslink component with critical signaling cascades, the current study was carried out to monitor possible changes in expression of this gene as well as some other important characteristics in wheat plants exposed to selenium nano-particle (nSe). Wheat seedlings were treated with nSe (0, 5, 10, and 50 mgl^?1). In germinating stage, plant fresh weights were reduced in nSe-treated seedlings, among which the nSe of 50 provoked roots turned brown. The nSe triggered the increases in the expressions of HSFA4A, in the plate. In the pot condition, shoot fresh weights in nSe-supplemented seedlings were decreased by approximately 22%. The nSe of 5 and 10 mgl^?1, respectively induced the expression of HSFA4A by 3.4- and 9.15-folds, contrasted with nSe50. Increasing times of sprays caused the dramatic reductions of the expression of HSFA4A in the nSe-supplemented groups. Moreover, the treatment of nSe stimulated expression of high molecular weight glutenin subunit 1Bx (Glu-1Bx) by fourfold, over the control. While the dramatic decrease in the expression of Glu-1Bx was recorded with increasing times of spray. Nitrate reductase activities were significantly improved by approximately 47% in nSe-fortified seedlings. Also, the foliar supplementation of nSe of 5 mgl^?1 provoked the significant inductions in peroxidase activity by 8%, whereas two other nSe treatments declined it. It may be stated that the nSe may modify the expression of HSFA4A, thereby triggering specific signaling and altering metabolism.     

The toxicity of endod extract to the early life stages of Dreissena bugensis

Toxicity bioassays were conducted on embryos and early larvae of quagga mussels, Dreissena bugensis, using a filtered aqueous extract and a lyophilized butanol extract of the soap berry plant Phytolacca dodecandra. Developmental stages exposed to each extract were embryos to trochophores (ca 3h‐17h), trochophores to D‐hinge larvae (ca 17h‐40h) and embryos to D‐hinge (3h‐ca 40). Over the whole embryo to D‐hinge exposure period, the aqueous extract resulted in a lowest observed effective concentration (LOEC) of 5mgl^‐1 although mortality did not exceed 50%. For the butanol extract, the LOEC was 2mgl^‐1 and the LC₅₀ was 2.1 mgl^‐1. For the aqueous extract, most of the endod toxicity was seen at the embryo stage, whereas for the butanol extract the toxicity was associated with the trochophore stage. Compared with other non‐oxidizing commercial molluscicides, endod has only moderate toxicity to early dreissenid life stages.     

Response of two tomato cultivars to field-applied proline under irrigation with saline water: Growth,chlorophyll fluorescence and nutritional aspects

The response of tomato (Solanum lycopersicum L.) to abiotic stress has been widely investigated. Recent physiological studies focus on the use of osmoprotectants to ameliorate stress damage, but experiments at a field level are scarce. Two tomato cultivars were used for an experiment with saline water (6.57 dS m^?1) and subsurface drip irrigation (SDI) in a silty clay soil. Rio Grande is a salinity-tolerant cultivar, while Heinz-2274 is the salt-sensitive cultivar. Exogenous application of proline was done by foliar spray at two concentrations (10 and 20 mg L^?1) during the flowering stage. Control plants were treated with saline water without proline. Proline at the lower concentration (10 mg L^?1) increased dry mass of different plant organs (leaves, stems, and roots) and it improved various chlorophyll a fluorescence parameters compared with controls. Regarding mineral nutrition, K⁺ and P were higher in different organs, while low accumulation of Na⁺ occurred. However, Mg²⁺ was very high in all tissues of Rio Grande at the higher concentration of proline applied. Thus, the foliar spray of proline at 10 mg L^?1 increased the tolerance of both cultivars. The growth of aboveground biomass of Heinz-2274 was enhanced by 63.5%, while Rio Grande improved only by 38.9%.     

Bioactive chemical constituents produced by endophytes and effects on rice plant growth

We investigated the bioactive potential of fungal endophytes isolated from the roots of Glycine max (L.) Merr. and Cucumis sativus. Initial screening results showed that endophytes, (Chrysosporium pseudomerdarium, Aspergillus fumigates and Paecilomyces sp., Penicillium sp., Phoma glomerata, and Paecilomyces formosus) were promoting the growth attributes (shoot length, chlorophyll contents, and biomass) of mutant and wild-type rice. To know whether, these endophytes were producing bioactive chemical constituents; the endophytes were grown in potato dextrose, czapek broth, and ICI mediums that resulted in varying mycelia biomass. The advance chromatographic analysis of endophytic fungal culture filtrate showed gibberellins (GA) production namely GA₁ (0.05–10.55 ngml^?1), GA₃ (0.48–9.0 ngml^?1), GA₄ (0.2–8.0 ngml^?1), GA₇ (1.4–6.5 ngml^?1), and GA₉ (0.03–1.05 ngml^?1) while among endophytes, P. glomerata and P. formosus were highly potent in GAs production. Additionally, the endophyte's culture also contained indole-3-acetic acid (0.23–71.51 µgml^?1). Furthermore, oxalic (0.009–0.3 mgl^?1), quinic (0.019–0.22 mgl^?1), malic (1.94–17.2 mgl^?1), and citric (0.012–0.95 mgl^?1) acids were also present in the endophytic cultures. The biochemical potential of endophytes greatly varied depending on nutrient source and pH, however, czapek broth rich in carbon revealed higher potential for bioactive chemical constituent's production. In conclusion, the current findings suggest that endophyte can play a vital role in essential crop plant growth by synthesizing a wide array of bioactive metabolites. Furthermore, an increased production of chemical constituents can be achieved by changing the in vitro growth conditions of endophytes     

The uptake and transport of silicon by perennial ryegrass and wheat

Summary In experiments with perennial ryegrass and wheat, silicon (Si) concentration in flowing solution culture was maintained constant at 0, 10 and 20 mgl⁻¹ (ryegrass) or 0, 20 and 40 mgl⁻¹ (wheat). Uptake and transport were measured in both species at frequent harvests over periods of up to 80 days. By the final harvests the initial differences in concentration between plants grown at high or low Si were largely eliminated. Much more Si was taken up by both species from the culture solution than was present in the transpiration stream. With ryegrass, the calculated cumulative amounts taken up through mass flow by plants grown at 10 or 20mgl⁻¹ Si, represented less than 40 and 70 per cent, respectively, of the total Si uptake. Up to 94 per cent of the Si taken up by wheat was transported rapidly to the shoots; older leaves contained up to 11.8 per cent Si.     

Effects of benthivorous bream (Abramis brama) and carp (Cyprinus carpio) on sediment resuspension and concentrations of nutrients and chlorophyll a

1. The effect of benthivorous bream and carp on sediment resuspension and the concentrations of nutrients and chlorophyll a were studied in sixteen experimental ponds (mean depth 1m, mean area 0.1 ha, sandy clay/clay sediment), stocked with bream or carp at densities varying from 0 to 500 kg ha^?1. Planktivorous perch (Perca fluviatilis L.) were added to some ponds to suppress zooplankton. 2. Suspended sediment concentrations increased linearly with biomass of benthivorous fish. Bream caused an increase of 46 g sediment m^?2 day^?1 per 100kg bream ha^?1 and a reduction of 0.38m^?1 in reciprocal Secchi disc depth, corresponding to an increase in the extinction coefficient of 0.34m^?1. 3. No relationship was found between size of fish and amount of resuspension, but the effect of bream was twice as great as that of carp. Benthivorous feeding was reduced in May because alternative food (zooplankton) was available. 4. Assuming a linear relationship, chlorophyll a level increased by 9.0 μgI^?1, total P by 0.03mgl^?1 and Kjeldahl-N by 0.48mgl^?1 per 100kg bream ha^?1. Silicate, chlorophyll a, total P and total N were all positively correlated with fish biomass, but orthophosphate showed no correlation.     

High‐throughput quantification of selenium in individual serum proteins from a healthy human population using HPLC on‐line with isotope dilution inductively coupled plasma‐MS

In this study, a method, based on dual column affinity chromatography hyphenated to isotope dilution inductively coupled plasma–quadrupole MS, was developed for selenium determination in selenoprotein P, glutathione peroxidase, and selenoalbumin in human serum samples from a group of healthy volunteers (n=399). Method improvement was achieved using methanol‐enhanced isotope dilution which resulted in improved sensitivity and removal of isobaric interferences. Although no human serum reference materials are currently certified for their selenium species levels, method development was conducted using human serum reference material BCR 637 and 639 as their Se species content has been reported in the previous studies, and thus comparisons were possible. The mean selenium concentrations determined for the 399 healthy volunteer serum samples were 23±10 ng Se mL^?1 for glutathione peroxidase, 49±15 ng Se mL^?1 for selenoprotein P and 11±4 ng Se mL^?1 for selenoalbumin. These values are found to be in close agreement with published values for a limited number of healthy volunteer samples, and to establish baseline Se levels in serum proteins for an apparently healthy group of individuals, thus allowing for subsequent comparisons with respective values determined for groups of individuals with selenium related health issues, as well as assist in the discovery of potential selenium biomarkers. Also, the relationship between Se serum protein levels and some anthropometric characteristics of the volunteer population were investigated. Additionally, further development of the analytical method used in this study was achieved by adding a size exclusion chromatography column after the two affinity columns via a switching valve. This allowed for the separation of small selenium‐containing molecules from glutathione peroxidase and thus enhanced the overall confidence in its identification.