Voltammetric determination of platinum in perfusate and blood: Preliminary data on pharmacokinetic study of arterial infusion with oxaliplatin

Because Platinum Group Elements have found widespread use in catalytic converters in cars and as chemotherapeutic agent, interest in the development of reliable analytical methods is carried out in order to monitor these analita in humans to protect the citizen's health.Considering that information on the levels of many trace elements in biological matrices is scarce and for many non-essential elements, baseline levels in the population, and especially in those particularly exposed to the risk are lacking, in this paper we optimize an analytical method for biological matrices, using a voltammetric technique to measure the concentration of Pt in blood and perfusate.The amount of Pt recovered from the blood and perfusate samples spiked with analita was observed to be meanly of 95% with 5–6% of R.S.D. These results indicated that proposed method for the determination of platinum in biological materials is accurate and reproducible.The amounts of platinum found in the blood samples of common ranged citizen were similar to quantification limit while in the patients the concentration ranged from 1.5 to 360 μg/L, in perfusate ranged from 0.7 to 9700 μg/l. The concentrations of Pt of populace and in patients before of infusion are in agreement with the level measured in the blood of unexposed patients.The proposed analytical method permits to determine the amount of Pt in the perfusate and subsequently absorbed by the target organs in order to determine the dose and timing of treatment and to avoid overdoses with related undesired effects.     

Application of Biomarkers to Assessment of Risk to Human Health from Exposure to Mycotoxins

Mycotoxins, the toxic compounds produced by mold secondary metabolism, represent a relevant source of danger to humans through alimentary channels. Efforts have been made by researchers and by national authorities to assess mycotoxin incidence in food, but often results are to be considered approximate or inaccurate due to the huge difficulties posed by sampling procedures. More recently the evaluation of mycotoxins in biological fluids have been given increasing attention since the results may offer valuable indications, although general on the overall status of mycotoxin contamination in food and feed. The assessment of the degree of exposure to these contaminants in the population or in specific groups can also be pursued. Researches on mycotoxins in biological fluids greatly contribute to clarify the mechanism of health impairment attributable to these toxic compounds and to elucidate the dose–response relationship. Despite the considerable efforts devoted to mycotoxin research in the past few decades, improvements in methodology has to be achieved mainly in sampling procedures and in quality assurance of the laboratories involved in mycotoxin analysis, as well as in the selection of appropriate biomarkers.     

Hygienic aspects related to burial

Burial grounds are generally provided by local authorities in cemeteries (subject to planning consent and to compliance with any considerations for environmental health). Their design has been submitted to studies of hydrogeological characteristics of soil with regard to its ability to purify wastewater coming from corpse decomposition, its ability to avoid the infiltration of pollutants in groundwater, and its ability to skeletonize buried corpses within the given times foreseen by the law in force. Greater environmental awareness has necessitated that new and existing burial grounds are assessed to determine the environmental load which they could release to soil or any downstream component. This problem arises in countries where there is a high density of built-up areas, a custom of disposing of the dead by burial, a lack of available spaces and suitable soils to designate as burial grounds. This paper reports some results from a study carried out on ground lands of Italy in order to revise articles 82 and 83 of the Decree No 285 of 1990 in force in relation to burial grounds. Soil permeability to water and air is a parameter of critical importance in relation to purification and/or diffusion of leachates from inhumed corpses in the soil, and in relation to its influence on the time necessary to completely skeletonize a human corpse.     

Solubilization of phenols in anionic polyelectrolyte gels with adsorbed cationic surfactant

Solubilization isotherms for various phenols in cetylpyridinium chloride (CPC)-polyelectrolyte gel aggregates have been determined in order to compare solubilization within these aggregates with that in free micelles and to examine the effects of gel chemistry and structure on solubilization. The isotherms describing solubilization are quite similar to those found for free surfactant in solution. Solutes that are more hydrophobic give rise to larger solubilization constants with trends similar to what is seen for hydrophobic effects in adsorption from aqueous solutions onto hydrophobic solids. The solubilization constants decrease as the fraction of solute in the aggregates increases, indicating that the solutes partition into the palisade region of the aggregates. Solubilization is found to be quite insensitive to changes in gel structure (cross-linker varying from 1% to 3%) and chemistry (poly(acrylic acid) versus poly(methacrylic acid) and neutralization from 50% to 100%). However, the switch from poly(acrylic acid) to poly(methacrylic acid) did give rise to a slight decrease in magnitude of the slope of the isotherm. The most significant factors appear to be the initial concentration of surfactant in solution and the ratio of surfactant solution to gel amount. A decrease in surfactant concentration (especially combined with an increase in solution volume) gives rise to a decrease in solubilization constants.     

Partitioning Solvophobic and Dispersion Forces in Alkyl and Perfluoroalkyl Cohesion

Fluorocarbons often have distinct miscibility properties compared to their nonfluorinated analogues. These differences may be attributed to van der Waals dispersion forces or solvophobic effects, but their contributions are notoriously difficult to separate in molecular recognition processes. Here, molecular torsion balances were used to compare cohesive alkyl and perfluoroalkyl interactions in a range of solvents. A simple linear regression enabled the energetic partitioning of solvophobic and van der Waals forces in the self‐association of apolar chains. The contributions of dispersion interactions in apolar cohesion were found to be strongly attenuated in solution compared to the gas phase, but still play a major role in fluorous and organic solvents. In contrast, solvophobic effects were found to be dominant in driving the association of apolar chains in aqueous solution. The results are expected to assist the computational modelling of van der Waals forces in solution.     

Optical Anisotropy of Porphyrin Nanocrystals Modified by the Electrochemical Dissolution

Reflectance anisotropy spectroscopy (RAS) coupled to an electrochemical cell represents a powerful tool to correlate changes in the surface optical anisotropy to changes in the electrochemical currents related to electrochemical reactions. The high sensitivity of RAS in the range of the absorption bands of organic systems, such as porphyrins, allows us to directly correlate the variations of the optical anisotropy signal to modifications in the solid-state aggregation of the porphyrin molecules. By combining in situ RAS to electrochemical techniques, we studied the case of vacuum-deposited porphyrin nanocrystals, which have been recently observed dissolving through electrochemical oxidation in diluted sulfuric acid. Specifically, we could identify the first stages of the morphological modifications of the nanocrystals, which we could attribute to the single-electron transfers involved in the oxidation reaction; in this sense, the simultaneous variation of the optical anisotropy with the electron transfer acts as a precursor of the dissolution process of porphyrin nanocrystals.     

Lab-on-chip methodologies for the study of transport in porous media: energy applications

We present a lab-on-chip approach to the study of multiphase transport in porous media. The applicability of microfluidics to biological and chemical analysis has motivated much development in lab-on-chip methodologies. Several of these methodologies are also well suited to the study of transport in porous media. We demonstrate the application of rapid prototyping of microfluidic networks with approximately 5000 channels, controllable wettability, and fluorescence-based analysis to the study of multiphase transport phenomena in porous media. The method is applied to measure the influence of wettability relative to network regularity, and to differentiate initial percolation patterns from active flow paths. Transport phenomena in porous media are of critical importance to many fields and particularly in many energy-related applications including liquid water transport in fuel cells, oil recovery, and CO(2) sequestration.     

Estimating Sun Exposure of Children in Day Care Nurseries in South Oxfordshire,UK

Exposure to ultraviolet radiation and sunburn during childhood and adolescence is linked to increased risks of melanoma and basal cell carcinoma later in life. Infants and toddlers are thought to be unusually vulnerable to UVR because of lower levels of melanin, a thinner stratum corneum and a higher surface area/body mass ratio. The aim of this study was to assess variations in the available erythema effective radiant doses to young children in day care nurseries in South Oxfordshire, UK over 7 years between 2008 and 2014. The data were analyzed in three distinct seasons according to a series of realistic exposure scenarios taking into account nursery routines. The results indicate the time of year when high doses are to be expected and provide strong support for arguments in favor of raising public awareness of sun protection earlier in the year.     

Amount of Melanin Granules in Human Hair Defines the Absorption and Conversion to Heat of Light Energy in the Visible Spectrum

One of the known important functions of hair is protection from extensive sunlight. This protection is accomplished in large part due to natural hair pigmentation which is known to reflect the number of melanin granules (melanosomes) in the hair shaft, and melanin variants. Melanin takes in excessive light energy and converts it to heat in a process called absorption; heat is then dissipated into the environment as infrared radiation, thereby protecting the underlying skin. We used transmission electron microscopy (TEM) to visualize the melanosome counts in samples of human hair, and used thermal microscopy to measure the temperature changes of the samples when exposed to green and blue light lasers. In our experiments green light conversion to heat was highly correlated to the number of melanosomes, whereas blue light conversion to heat was less correlated, which may be because the reddish melanosomes it contains are less effective in absorbing energy from the blue spectrum of light. Anyway, we have shown the metals accumulation in the melanin can be easily visualized with TEM. We confirmed that the amount of melanin granules in human hair defines the conversion to heat of light energy in the visible spectrum.     

Quantification of particle-bubble interactions using atomic force microscopy: A review

The attachment of particles to bubbles in solution is of fundamental importance to several industrial processes, most notably in the process of froth flotation. During this process hydrophobic particles attach to air bubbles in solution, which allows them to be separated as froth at the surface. The addition of chemicals can help to modulate these interactions to increase the yield of the minerals of interest. Over the past decade the atomic force microscope (AFM) has been adapted for use in studying the forces involved in the attachment of single particles to bubbles in the laboratory. This allows the measurement of actual DLVO (Derjaguin, Landau, Vervey and Overbeek) forces and adhesive contacts to be measured under different conditions. In addition contact angles may be calculated from features of force versus distance curves. It is the purpose of this article to illustrate how the colloid probe technique can be used to make single particle-bubble interactions and to summarise the current literature describing such experiments.     

Theoretical study of the mechanism of proton transfer in tautomeric systems: Alloxan

Semiempirical SCF-MO studies of tautomerism in alloxan preclude the possibility of direct proton transfer in the gas phase due to the strain in the four-centred transition state, in which the proton being transferred is forced to come close to the positively charged carbon atom at the opposite corner of the four-membered ring. However, in aqueous solution, the activation barrier reduces appreciably, not only due to reduction in strain, but also due to charge separation in the transition state, which is stabilized due to ionic resonance. The N-H bond is almost broken, while the O-H bond is only partially formed in the transition state. The other stabilizing effect in aqueous solution is due to bulk solvent dielectric effects, which stabilize the transition state to a greater extent due to its higher dipole moment. Although the transition states for proton transfer to the neighbouring oxygen atoms on either side have comparable energies, as the mechanisms of proton transfer leading to the formation of the 2-hydroxy and 4-hydroxy tautomers are similar, bulk solvent effects are larger in the latter due to the higher dipole moment of the transition state. The reason is the almost complete separation of the two entities, i.e. the alloxan anion and the hydronium ion in the latter case, indicating that in this case a dissociative mechanism of the kind encountered in acid-base equilibria is operating.     

Experiences in the measurement of RBC-bound IgG as markers of cell age

An immunologically mediated pathway has been largely accepted to be one of the mechanisms involved in the clearance of senescent or prematurely damaged RBC. According to this pathway, RBC removal is mediated by binding of naturally occurring IgG to clustered integral membrane proteins, followed by complement deposition. The validation of an immunoenzymatic method for the detection of RBC-bound autologous IgG is presented. The use of RBC-bound IgG as an index related to red cell age was evaluated by measuring IgG binding in RBC treated with the clustering agent ZnCl2, in density fractionated RBC and in a selected group of patients expected to have an altered RBC life span. The immunoenzymatic method for IgG detection resulted to be reproducible (CV = 3.4%). IgG binding to in vitro clustered RBC was found to be enhanced to a very great extent, about 20 times higher with respect to untreated RBC. A slight but significant increase (about 1.8-fold) in membrane-bound IgG was observed in the highest density fraction of normal RBC, which constituted 1% of the total cells. A significantly greater number of RBC-bound IgG was measured in splenectomized beta-thalassemia intermedia patients and in subjects with secondary decreases in the C3 complement fraction concentration.     

Plasma Processing of Scaffolds for Tissue Engineering and Regenerative Medicine

Plasma processes are largely employed in the biomedical field for different kind of materials. In particular, in tissue engineering, biomaterials need to be totally integrated with biological systems in order to be employed as substitutes of artificial prostheses. Since most materials do not allow a correct integration with the biological environment, plasma processes have been demonstrated to be very versatile in altering the material surface properties in order to improve the biocompatibility of materials. The challenge is to plasma modify 3D scaffolds in order to be used for in vivo regeneration of human tissues. The correct 3D biointegration inside living tissues is the crucial objective, towards which many aspects are directed, from the material engineering to its surface modification and affinity with the biological environment. In this paper, the advances in low pressure plasma processes, applied to both 2D rigid substrates and 3D porous structures, are discussed. Further an in vivo experiment in ovine animals using plasma processed 3D scaffolds is illustrated.     

紫外拉曼光谱研究焙烧气氛对氧化锆相变的影响

 以紫外拉曼光谱技术研究了在不同焙烧气氛中氧化锆样品的表面晶相结构及其转变过程．结果表明，在有氧气氛中焙烧的氧化锆样品易转变为单斜相，而在惰性气氛中焙烧可以有效地稳定样品体相和表面的四方相结构．在缺氧气氛中焙烧的样品暴露于空气中后，表面极易转变为单斜相，而其体相仍为四方相结构，这表明四方相氧化锆在样品表面是极不稳定的．     

QSAR for acetylcholinesterase inhibition and toxicity of two classes of phosphoramidothioates

Methamidophos (Met) is a weak inhibitor of housefly head AChE but at the same time it is highly toxic to the common housefly. The lethality of Met is believed to be due to AChE inhibition. An extensive QSAR study may help in determining the mode of action of Met in vivo and in vitro and provide a rational for its high insecticidal toxicity. Acephate (Ace), like Met, is a poor inhibitor of AChE in vitro and has a comparable to Met insect toxicity in vivo. Contrary to Met, though, Ace has much lower mammalian toxicity. Understanding the structural properties which make insecticides toxic to insects but not to mammals is of great importance, since mammals (including humans) are inadvertently exposed to these compounds. Our results were consistent with the model in which both the in vitro and in vivo toxicity of Met depends on the inhibition of the active center of AChE by the unchanged Met. An optimal susceptibility to hydrolysis is needed for Met and its analogs to have high insecticidal activity since in order to phosphorylate AChE they need to be hydrolyzed and at the same time their stability is of great importance in vivo for accumulating at the site of action. The insecticidal activity of Ace analogs may be due to direct interaction with the active center of the AChE. The mammalian toxicity of Ace analogs may be due to interaction with an 'allosteric' reaction center in the AChE.     

Flow-induced conformational changes in gelatin structure and colloidal stabilization

Flow can change the rate at which solutes adsorb on surfaces by changing mass transfer to the surface, but moreover, flow can induce changes in the conformation of macromolecules in solution by providing sufficient stresses to perturb the segmental distribution function. However, there are few studies where the effect of flow on macromolecules has been shown to alter the structure of macromolecules adsorbed on surfaces. We have studied how the local energy dissipation alters the adsorption of gelatin onto polystyrene nanoparticles ( r = 85 nm). The change in the nature of the adsorbed layer is manifest in the change in the ability of the nanoparticles to resist aggregation. Circular dichroism spectroscopy was used to assess conformational changes in gelatin, and dynamic light scattering was used to assess the colloid stability. Experiments were conducted in a vortex jet mixer where energy density and mixing times have been quantified; mixing of the gelatin and unstable nanoparticles occurs on the order of milliseconds. The adsorption of the gelatin provides steric stabilization to the nanoparticles. We found that the stability of the gelatin-adsorbed nanoparticles increased with increasing mixing velocities: when the mixing velocities were changed from 0.9 to 550 m/s, the radius of the nanoclusters (aggregates) formed 12 h after the mixing decreased from 2620 to 600 nm. Increasing temperature also gave rise to similar trends in the stability behavior with increasing temperature, leading to increasing colloid stability. Linear flow birefringence studies also suggested that the velocity fields in the mixer are sufficiently strong to produce conformational changes in the gelatin. These results suggest that the energy dissipation produced by mixing can activate conformational changes in gelatin to alter its adsorption on the surfaces of nanoparticles. Understanding how such conformational changes in gelatin can be driven by local fluid mechanics and how these changes are related to the adsorption behavior of gelatin is very important both industrially and scientifically.     

Occupational and environmental laboratory medicine: A network of EQAS organisers

Most people in any community come into contact with chemicals that are potentially harmful to their health. Some elements are essential to health and inadequate amounts in food may also lead to ill health. Measurement of chemicals in blood, urine or other specimens is a fundamental feature of studies undertaken in the field of Occupational and Environmental Laboratory Medicine (OELM). Results are used to assess the risk for either overexposure or deficiency of essential nutrients. External Quality Assessment Schemes (EQAS) aid laboratories to achieve accurate and consistent data and 11 organisers of EQAS in Europe and North America are working to improve the effectiveness of their activities.The aims of the Network of EQAS Organisers in OELM are to stimulate improvements in analytical results, establish equivalence of assessment among Schemes, collaborate to enhance the practice of EQA including whenever possible to warrant traceability of EQAS to primary standards.Presented at the Eurachem PT Workshop September 2005, Portorož, Slovenia.     

Review of Mesoscopic Modeling of Liquids in Materials Science

Mesoscopic theories can be used in the field of materials science to derive local average properties of relevance to the engineer such as flux, pressure, average density or composition. In the following density functional theory will be described and applied to different systems of interest and in particular, to materials formed from complex liquids as characterized by atomic structure and the type of interaction between the individual particles. The calculation of the solid to liquid transition will be explained in detail as a prototype for other order disorder transitions. The theory of polymers in solution will be revisited and used to calculate phase separation in mixtures. An extension of the theory to include the orientation of rodlike, long molecules will be applied to liquid crystals. In the presence of an interface, the system properties depend strongly on position in space and can be predicted from parameters obtained in the bulk in a square gradient approximation for sufficiently smooth and small deviations from the uniform distribution. A phase transition is often used to prepare heterogeneous materials by nucleation and growth. It will be shown how the equilibrium theory can be extended to study the dynamics of nonequilibrium phenomena.     

杨石先对农药化学学科的重要贡献及其学术思想

杨石先先生一生献身于我国的教育事业与化学学科的发展,在62年中为我国培养了无数高质量的科教人才。他除了长期担任南开大学校长之外, 还创建了我国大学第一个专职研究所,即元素有机化学研究所。他率先开展了我国元素有机化学与农药化学的科学研究,领导了元素有机化学国家重点实验室的建立,是我国元素有机化学和农药化学的奠基人和开拓者。他倡导用有机化学的专业知识,科学和系统地开展农药化学研究,组建队伍获得20项科研成果,发表上百篇科学与论述性论文,为我国开展自主创新农药研究事业作出重要贡献。在农药化学学科的学术思想中,他强调要弄清该学科的交叉性、系统性和内在规律性,倡导要学习国际先进经验,要结合国情自主创新,要为国家经济服务,要对世界农药科技做出贡献。他毕生对人才培养给予了特别的重视,为我国科技事业持续发展作出了重大贡献。     

Microfluidic technologies as platforms for performing quantitative cellular analyses in an in vitro environment

Quite often, important cellular events occur in environments that are either not amenable to implanted sensors or other types of molecular probes. In such cases, a viable alternative to taking the sensor or probe to the biological sample of interest is to bring the sample of interest out of its natural environment to one that is more conducive to the measurement scheme. The disadvantage of the latter approach is that the sample may not behave in the same manner in vitro as it does in vivo, or that the agonists and other stimuli to which the sample is subjected to in vivo are no longer present. In this Tutorial Review, the authors attempt to provide some guidance, based on their own experiences and those of other scientists, to performing cellular measurements in a quantitative manner under in vitro conditions. Due to the expansive literature on analyses involving cells, the authors have limited this Tutorial Review to those methods involving microfluidic technologies, both in microbore tubing and in microfabricated channels. Initial reports of analyses involving cells in microbore tubing were first reported nearly two decades ago, while those in microfabricated fluidic devices appeared over a decade ago. However, more recently, the complexity of cell analyses using fabricated microfluidic devices (as opposed to microbore tubing) has increased due in part to the improvements in fabrication technologies, fluid handling and delivery capabilities, advances in coatings of the channels within the microfluidic device, and integrated detection schemes. Examples of cellular analyses in microbore tubing and in fabricated microfluidic devices will be given, as well as associated advantages and challenges. Finally, the authors' thoughts on cellular analyses are presented here using the classical steps in an analysis as a guide.