Organoarsenic compounds in plants and soil on top of an ore vein

Plants and soil collected above an ore vein in Gasen (Austria) were investigated for total arsenic concentrations by inductively coupled plasma mass spectrometry (ICP‐MS). Total arsenic concentrations in all samples were higher than those usually found at non‐contaminated sites. The arsenic concentration in the soil ranged from ∼700 to ∼4000 mg kg⁻¹ dry mass. Arsenic concentrations in plant samples ranged from ∼0.5 to 6 mg kg⁻¹ dry mass and varied with plant species and plant part. Examination of plant and soil extracts by high‐performance liquid chromatography–ICP‐MS revealed that only small amounts of arsenic (<1%) could be extracted from the soil and the main part of the extractable arsenic from soil was inorganic arsenic, dominated by arsenate. Trimethylarsine oxide and arsenobetaine were also detected as minor compounds in soil. The extracts of the plants (Trifolium pratense, Dactylis glomerata, and Plantago lanceolata) contained arsenate, arsenite, methylarsonic acid, dimethylarsinic acid, trimethylarsine oxide, the tetramethylarsonium ion, arsenobetaine, and arsenocholine (2.5–12% extraction efficiency). The arsenic compounds and their concentrations differed with plant species. The extracts of D. glomerata and P. lanceolata contained mainly inorganic arsenic compounds typical of most other plants. T. pratense, on the other hand, contained mainly organic arsenicals and the major compound was methylarsonic acid. Copyright © 2002 John Wiley & Sons, Ltd.     

Effect of surface charge of magnetite nanoparticles on their internalization into breast cancer and umbilical vein endothelial cells

Internalization of magnetite nanoparticles with diameter of approximately 40 nm into normal and cancer cells was examined by microscopic observation and flow cytometry. Magnetite nanoparticles were synthesized by hydrolysis in an aqueous solution containing ferrous chloride with organic amines as a base. It was demonstrated that the difference in surface charge of magnetite nanoparticles brought about the difference in uptake efficiency. The nanoparticles with positive charge showed higher internalization into human breast cancer cells than the nanoparticles with negative charge, while the degree of internalization of the positively- and negatively-charged nanoparticles into human umbilical vein endothelial cells (HUVEC) was almost the same.     

Blood compatible heteratom-doped carbon dots for bio-imaging of human umbilical vein endothelial cells

Carbon dots have unique advantages in biological applications owing to their excellent optical prope rties.However,the biosafety evaluation of carbon dots has limitations owing to cytotoxicity in vitro,and the re is little pre-safety evaluation before in vivo and clinical applications.Whether the carbon dots are or not suitable for applications in vivo,evaluation analysis can be made based on hemolysis and changes in erythrocyte morphology.In this work,a green fluorescent N,S-doped carbon dots(N,S-CDs)were obtained by hydrothermal method,tobias acid,and m-phenylenediamine as precursors.N,S-CDs not only possessed excellent dispersibility,uniform particle size,high quantum yield(37.2%)and stable photoluminescence property but also retain their photostability and stro ng fluorescence intensity in the acid/alkaline solutions,different ionic strengths(NaCl)and under 365 nm UV illumination.Moreove r,the N,S-CDs displayed low cytotoxicity and high cellular uptake efficiency in human umbilical vein endothelial cells(HUVEC)and excellent blood compatibility to the erythrocyte.It is foreseeable that N,S-CDs could be further studied as a promising biological imaging agent in vivo.     

Consistent patterns in leaf lamina and leaf vein carbon isotope composition across ten herbs and tree species

Wide‐spread post‐photosynthetic fractionation processes deplete metabolites and plant compartments in ¹³C relative to assimilates to varying degrees. Fragmentation fractionation and exchange of metabolites with distinct isotopic signatures across organ boundaries further modify the patterns of plant isotopic composition. Heterotrophic organs tend to become isotopically heavier than the putative source material as a result of respiratory metabolism. In addition fractionation may occur during metabolite transport across organ and tissue boundaries. Leaf laminae, veins and petioles are leaf compartments that are arranged along a gradient of increasing weight of heterotrophic processes and along a transport chain. Thus, we expect to find consistent patterns of isotopic signatures associated with this gradient. Earlier studies on leaves of Fagus sylvatica, Glycine max, and Saccharum officinarum showed that the organic mass and cellulose of major veins or petioles were consistently more positive than the respective fraction in leaf laminae. The objective of the current study was to assess whether this pattern can be detected in a greater set of plant species. Leaves from ten species were collected in the summer of 2006 outdoors and in glasshouses. Leaf laminae including small veins were separated from the major veins and the isotopic signatures of the organic mass, and the soluble and non‐soluble fractions were measured for laminae and veins separately. The organic mass, and the soluble and non‐soluble fractions of leaf laminae, were depleted in ¹³C relative to the veins in all cases. A general trend for the signature of organic mass being more depleted in ¹³C than the soluble fraction is in accordance with well‐known patterns of fractionation between metabolites. Copyright © 2009 John Wiley & Sons, Ltd.     

Comparison and validation of calibration methods for in vivo SPME determinations using an artificial vein system

The success of in vivo solid phase microextraction (SPME) depends significantly on the selection of calibration method. Three kinetic in vivo SPME calibration methods are evaluated in this paper: (1) on-fibre standardization (OFS), (2) dominant pre-equilibrium desorption (DPED), and (3) the diffusion-based interface (DBI) model. These are compared in terms of precision, accuracy, and ease of experimental use by employing a flow device simulating an animal circulatory system. In addition, the kinetic calibration methods were validated against established SPME equilibrium extraction (EE) external calibration and a conventional sample preparation method involving protein precipitation. The comparison was performed using a hydrophilic drug fenoterol as the analyte of interest. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) was used for the determinations. All three kinetic methods compared well with both EE extraction and the conventional method in terms of accuracy (93-119%). In terms of precision, the DBI model had the best precision in whole blood and buffered phosphate saline solution with %RSD similar to the standard techniques (9-15%). DPED had the poorest precision of %RSD (20-30%) possibly due to errors associated with uncertainty in the amount of standard loaded on-fibre and remaining on the fibre after desorption. In addition, incurred errors could result due to the greater number of fibres used in comparison to the other two calibration methods. The precision of the OFS procedure was better than for DPED primarily because the use of multiple fibres is eliminated. In terms of the ease of use for calibration, the DBI model was the simplest and most convenient as it did not require standards once it had been calibrated or the uptake constant was calculated. This research suggests the potential use of DBI model as the best kinetic calibration method for future in-vein blood SPME investigations.     

An on-line method for determining ATPase bioactivity and its application to human umbilical vein endothelial cell membrane

Based on the determination of inorganic phosphate (the product of ATP dephosphorylation by ATPase), a method for on-line determination of bioactivity of ATPase on cell membrane is presented, in which on-line sampling of cell membrane and separation of inorganic phosphate is employed in a flow injection system. The method has been successfully applied to the investigation of variation of ATPase from human umbilical vein endothelial cell membrane; the results show that ATPase activity decreases with elapsed time studied, which may supply important information for the pertinent studies on cell membrane enzymes bioactivity.     

A tag-less method for direct isolation of human umbilical vein endothelial cells by gravitational field-flow fractionation

The analysis of cellular and molecular profiles represents a powerful tool in many biomedical applications to identify the mechanisms underlying the pathological changes. The improvement of cellular starting material and the maintenance of the physiological status in the sample preparation are very useful. Human umbilical vein endothelial cells (HUVEC) are a model for prediction of endothelial dysfunction. HUVEC are enzymatically removed from the umbilical vein by collagenase. This method provides obtaining a good sample yield. However, the obtained cells are often contaminated with blood cells and fibroblasts. Methods based on negative selection by in vitro passages or on the use of defined marker are currently employed to isolate target cells. However, these approaches cannot reproduce physiological status and they require expensive instrumentation. Here we proposed a new method for an easy, tag-less and direct isolation of HUVEC from raw umbilical cord sample based on the gravitational field-flow fractionation (GrFFF). This is a low-cost, fully biocompatible method with low instrumental and training investments for flow-assisted cell fractionation. The method allows obtaining pure cells without cell culture procedures as starting material for further analysis; for example, a proper amount of RNA can be extracted. The approach can be easily integrated into clinical and biomedical procedures.     

In situ formation and scanning electrochemical microscopy assisted positioning of NO-sensors above human umbilical vein endothelial cells for the detection of nitric oxide release

Pt microelectrodes (50 μm diameter) were positioned by means of scanning electrochemical microscopy assisted z-approach curves and in situ modified with nickel tetrasulfonated phthalocyanine tetrasodium salt as electrocatalytic layer for the specific oxidative detection of nitric oxide. The thus modified electrodes were then moved over a layer of adherently growing human umbilical vein endothelial cells (HUVEC) in order to amperometrically detect nitric oxide (NO) released from the cells upon stimulation with bradykinin. This approach actually takes advantage of the use of SECM to define a sequential procedure that enables the in situ functionalisation of the SECM tip thus allowing to accurately control the separation between the functionalised SECM tip and the cell population.     

Expression of integrin beta1 and its roles on adhesion between different cell cycle hepatocellular carcinoma cells (SMMC-7721) and human umbilical vein endothelial cells

To investigate expression of integrin β₁ and its roles on adhesion between different cell cycle hepatocellular carcinoma cell (HCC) and human umbilical vein endothelial cells (HUVEC), the synchronous G₁ and S phase HCC were achieved through thymine-2-deoxyriboside and colchicines sequential blockage method and double thymine-2-deoxyriboside blockage method, respectively. Expression of integrin β₁ on hepatocellular carcinoma cells was detected with flow cytometer. Further, the adhesive force of HCC to HUVEC and the role of integrin β₁ in this adhesive course were studied by micropipette aspiration technique. The results showed that percentage of each cyclic phases of the controlled HCC (non-synchronous) are: G₂+M phase, 11%; G₁ phase, 54%; S phase, 36%; the synchronous rates of G₁ and S phase HCC amount to 74 and 98%, respectively. The expressive fluorescent intensity of integrin β₁ in G₁ phase HCC is depressed significantly than the values of S phase and controlled HCC. Accordingly, the adhesive forces of G₁ phase HCC to HUVEC was significantly lower than the value of S phase cells (P<0.01), but it has no remarkable difference when compared the adhesive force values of S phase HCC with control; the contribution of integrin β₁ was about 50% in the adhesion of HCC to HUVEC. It suggested that HCC would be synchronized preferably in G₁ and S phase with thymine-2-deoxyriboside and colchicines, the adhesive molecule integrin β₁ expressed in a high lever in HCC and presented differences in vary cell cycle, and integrin β₁ played an important roles in adhesion of HCC to HUVEC. Possibly, S phase HCC take a great action in this adhesive course.     

252. Synthesis and reactions of droso- and isodrosopterin. Pteridines. LIV

The synthesis of the Drosophila pigments droso- and isodrosopterin ( 7 ) from 7.8-dihydropterin ( 3 ) and 2-hydroxy-3-oxobutyric acid ( 4 ) is described. A reaction mechanism is discussed and proven by isotope experiments. Droso- and isodrosopterin form in weak acidic medium in the presence of NH ions two red reaction products each one of which seems to be identical with neodrosopterin.