Analytical strategy for the assessment of the protein glycation status in uremic patients by high-performance liquid chromatography.

We propose a newly integrated procedure for the analysis of furosine (early glycation product) and pentosidine (glycoxidation end-product) in plasma proteins and the simultaneous assessment of advanced glycation end-product (AGE) peptides and free pentosidine in plasma. In order to determine furosine and protein-linked pentosidine, plasma proteins were hydrolyzed in 8 M HCl and each analyte was purified by solid-phase extraction. Furosine was determined by ion-pair RP-HPLC methodology with isocratic elution and spectrophotometric detection at 280 nm and pentosidine by ion-pair RP-HPLC by using gradient elution and fluorimetric detection at 335/385 nm. To assess free pentosidine concentration and simultaneously evaluate the AGE peptides, an aliquot of plasma sample was diluted and ultrafiltered by using Centricon 10 M(r) < or = 10,000) ultrafiltration membranes. Free pentosidine and AGE peptides were analysed by ion-pair RP-HPLC, by using gradient elution and fluorimetric detection at 385 nm upon excitation at 335 nm. The HPLC methodology has been successfully used for the determination of glycation and glycoxidation protein status in uremic patients.     

Optimizing the energy status of skin cells during solar radiation.

Ionizing- and ultraviolet-radiation cause cell damage or death by directly altering DNA and protein structures and by production of reactive oxygen species (ROS) and reactive carbonyl species (RCS). These processes disrupt cellular energy metabolism at multiple levels. The formation of DNA strand breaks activates signaling pathways that consume NAD, which can lead to the depletion of cellular ATP. Poly(ADP)-ribose polymerase (PARP-1) is the enzyme responsible for much of the NAD degradation following DNA damage, although numerous other PARPs have been discovered recently that await functional characterization. Studies on mouse epidermis in vivo and on human cells in culture have shown that UV-B radiation provokes the transient degradation of NAD and the synthesis of ADP-ribose polymers by PARP-1. This enzyme functions as a component of a DNA damage surveillance network in eukaryotic cells to determine the fate of cells following genotoxic stress. Additionally, the activation of PARP-1 results in the activation of a nuclear proteasome that degrades damaged nuclear proteins including histones. Identifying approaches to optimize these responses while maintaining the energy status of cells is likely to be very important in minimizing the deleterious effects of solar radiation on skin.     

Present status of the Technological Laboratory at the LMU Munich

The Technological Laboratory of LMU is undergoing major changes. Most important of them is raising a DLC-Factory’s for diamond-like-carbon (DLC) foils production and a shutdown of the Hot-Lab Facility. Current Laboratory status and development plans are presented in this paper.     

Laboratory UV exposure: risk assessment and protective measures

In research laboratories ultraviolet radiation is widely used, particularly in photochemistry and photobiology, as a sterilizing agent and for the characterization of samples. The results of a survey conducted near several university laboratories are presented with the aim of quantifying exposure levels to UV-incoherent radiation and to assess individual risk for researchers and students. It has been shown that exposure is not negligible, especially if safety procedures are neglected and personal protective equipments, described in this study, are not used.     

Laboratory cost management.

Laboratory cost management deals with the economical use of laboratory resources such as capital, equipment and manpower. Cost analysis is a tool for cost management, by means of which the laboratory manager can properly set priorities, choose appropriate test procedures, set personnel policies and make better investments of his resources. This article sets out some important aspects of cost analysis, such as the construction of cost curves, the factors that enter into cost analysis, the context in which cost analysis is used, and the limitations of this type of analysis.     

Grid-based energy density analysis: implementation and assessment

Grid-based energy density analysis (grid-EDA) that decomposes the total energy into atomic energies by a space-partitioning function is proposed. The kinetic energy, nuclear attraction, and exchange-correlation functional are evaluated on grid points and are split into atomic contributions. To reduce numerical errors in the conventional scheme of numerical integration, the electronic Coulomb and HF exchange interactions are evaluated by the pseudospectral method, which was first applied to an ab initio method by Friesner [Chem. Phys. Lett. 116, 39 (1985)], and are decomposed into atomic contributions. Grid-EDA using the pseudospectral method succeeds in ensuring less than 1 kcalmol error in total energies for small molecules and providing reliable atomic energy contributions for the problematic lithium cluster, which exhibits a strong basis-set dependence for Mulliken-type EDA. Also, site-dependent atomization energies are estimated by grid-EDA for cluster models such as Li(48), C(41)H(60), and Mg(32)O(32). Grid-EDA reveals that these models imitate crystal environments reasonably because atomization energies estimated from the inner atoms of the models are close to the experimental cohesive energies.     

The present status of the selfshielded low energy electron accelerator

This paper details the history and the present status of the low energy electron accelerator in Japan, introduces potential applications, and describes the construction of the equipment.     

Quantum chemical assessment of the binding energy of CuO+

We present a detailed theoretical investigation on the dissociation energy of CuO(+), carried out by means of coupled cluster theory, the multireference averaged coupled pair functional (MR-ACPF) approach, diffusion quantum Monte Carlo (DMC), and density functional theory (DFT). At the respective extrapolated basis set limits, most post-Hartree-Fock approaches agree within a narrow error margin on a D(e) value of 26.0 kcal mol(-1) [coupled-cluster singles and doubles level augmented by perturbative triples corrections, CCSD(T)], 25.8 kcal mol(-1) (CCSDTQ via the high accuracy extrapolated ab initio thermochemistry protocol), and 25.6 kcal mol(-1) (DMC), which is encouraging in view of the disaccording data published thus far. The configuration-interaction based MR-ACPF expansion, which includes single and double excitations only, gives a slightly lower value of 24.1 kcal mol(-1), indicating that large basis sets and triple excitation patterns are necessary ingredients for a quantitative assessment. Our best estimate for D(0) at the CCSD(T) level is 25.3 kcal mol(-1), which is somewhat lower than the latest experimental value (D(0) = 31.1 ± 2.8 kcal mol(-1)[semicolon] reported by the Armentrout group) [Int. J. Mass Spectrom. 182/183, 99 (1999)]. These highly correlated methods are, however, computationally very demanding, and the results are therefore supplemented with those of more affordable DFT calculations. If used in combination with moderately-sized basis sets, the M05 and M06 hybrid functionals turn out to be promising candidates for studies on much larger systems containing a [CuO](+) core.     

Determination of an empirical energy function for protein conformational analysis by energy embedding

It is quite easy to propose an empirical potential for conformational analysis such that given crystal structures lie near local minima. What is much more difficult, is to devise a function such that the native structure lies near a relatively deep local minimum, at least in some neighborhood of the native in conformation space. An algorithm is presented for finding such a potential acting on proteins where each amino acid residue is represented by a single point. When the given structure is either an α-helical, β-strand, or hairpin bend segment of pancreatic trypsin inhibitor, the resulting potential function in each case possesses a deep minimum within 0.10 Å of the native conformation. The improved energy embedding algorithm locates a marginally better minimum in each case only 0.1–1.3 Å away from the respective native state. In other words, this potential function guides a conformational search toward structures very close to the native over a wide range of conformation space.     

Laboratory systems to evaluate the toxicity of polymers combustion products and hazard assessment

Several laboratory systems have been proposed to evaluate the toxicity of combustion products of materials. Generally, the “fire models” were poorly instrumented, excepted the analysis of the major toxicants. Better informations being needed in this respect, a furnace has been made, based on the 2 zones NBS model, and allowing the evaluation of flammability, heat release and weight loss. Moreover, opacity and toxic gases are monitored. The time to incapacitation is probably the more realistic toxicological evaluation. It is worth while to rank materials by an hazard assessment, separating the variables involved in the fire hazard and the variables corresponding to the toxicological hazards and to plot them in a two-dimensional graphic which looses less information than an index.     

Laboratory measurement of human cytokines.

Cytokines mediate and modulate different physiological systems. Accurate and sensitive methods for their measurement are being developed using bioassays, immunoassays, measurement of their mRNA, receptor binding assays, and immunochemical procedures. The most clinically significant cytokines and their assay methods are briefly reviewed. The need for standardization of assays is stressed.     

Fuel cell performance assessment for closed-loop renewable energy systems

Fuel cells and electrolysis are promising candidates for future energy production from renewable energy sources. Usually, polymer electrolyte fuel cell systems run on hydrogen and air, while the most of electrolysis systems vent out oxygen as unused by-product. Replacing air with pure oxygen, fuel cell electrochemical performance, durability and system efficiency can be significantly increased with a further overall system simplification and increased reliability. This work, which represents the initial step for pure H_2/O_2 polymer electrolyte fuel cell operation in closed-loop systems, focuses on performance validation of a single cell operating with pure H_2/O_2 under different relative humidity(RH) levels, reactants stoichiometry conditions and temperature. As a result of this study, the most convenient and appropriate operative conditions for a polymer electrolyte fuel cell stack integrated in a closed loop system were selected.     

Laboratory tests in rheumatology.

The most commonly used laboratory tests in the diagnosis and monitoring of rheumatic diseases are reviewed. Particular emphasis is placed on antinuclear antibodies as markers of specific rheumatic disorders and disease subsets. The use of synovial fluid tests to differentiate between inflammatory and noninflammatory rheumatic disorders is described as well as the use of common hematological tests.     

Exploring protein energy landscapes with hierarchical clustering

In this work we present a new method for investigating local energy minima on a protein energy landscape. The CABS (CAlpha, CBeta and the center of mass of the Side chain) method was employed for generating protein models, but any other method could be used instead. Cα traces from an ensemble of models are hierarchical clustered with the HCPM (Hierarchical Clustering of Protein Models) method. The efficiency of this method for sampling and analyzing energy landscapes is shown.     

Metal-organic frameworks for electrochemical energy conversion: status and challenges

正The quickly expanded energy consumption based on traditional fossil fuels has resulted in energy crises and severe environmental problems. Developing sustainable energy conversion technology is an important issue confronting the global energy security and consumption. Electrochemical energy storage and conversion is one of the most perspective renewable ways to produce carbon-free fuels via water splitting, and convert chemicals into electricity by fuel cells     

Quantitative assessment of human serum high-abundance protein depletion

The aim of this study is to quantify the effectivity of the depletion of human high-abundance serum and plasma proteins for improved protein identification and disease marker candidate discovery and to assess the risk of concomitant removal of relevant marker proteins. 2-DE and bottom-up shotgun MS combining 2-D capillary chromatography with MS/MS were applied in parallel for the analysis of fractions resulting from the depletion procedure. For many proteins the factors of enrichment by the depletion were obvious allowing their enhanced detection and identification upon high-abundance protein depletion. Nano-liquid chromatography linked MS allowed the efficient identification of several low-abundant proteins that were not identified on the 2-DE gels. Resolving the fractions that were eluted from the matrix upon depletion indicated unspecific binding of disease relevant proteins in plasma samples from acute myocardial infarction patients. The unspecific binding to the depletion matrix of inflammatory markers spiked into the serum was found to depend on the type of capturing agent used. Polyclonal avian antibodies (IgY) displayed the least unspecific binding due to the high immunogenicity of mammalian proteins in avian hosts.     

Fluorescence resonance energy transfer measurements on cell surfaces. A spectroscopic tool for determining protein interactions.

The interaction of cell surface components may influence several events during the process of transmembrane signalling. Receptor clustering, conformational changes and altered molecular interactions often play essential roles in the final outcome of ligand receptor interactions. Fluorescence resonance energy transfer (FRET) is an excellent tool which can be used to determine distance relationships and supramolecular structure on cell surfaces. This paper reviews the theoretical basis of fluorescence resonance energy transfer, its spectrofluorometric and flow cytometric applications, and provides a critical evaluation of the methods. Finally, examples are given to illustrate the use of the method of fluorescence resonance energy transfer in solving biological problems.     

Z dependence of mass attenuation coefficient at 59.54 keV photon energy: experimental assessment of binding energy effects

Mass attenuation coefficients of 59.54 keV photons were measured in elements with atomic number ranging from low to high, and including lanthanides whose K-shell binding energies were close to those of incident photons. Comparison with the most reliable data from tabulations in current use reveals some disagreement in the interval of binding energy values close to 59.54 keV. The significant disagreement reported by other authors for certain elements was not confirmed by the present investigation.