bluuebunny/crossref_metadata_2025 huggingface dataset:
Prediction of aqueous phase pH for enzymatic synthesis of peptides in aqueous–organic biphasic systems
Authors: Fan Ke‐Ke , Ouyang Pingkai , Wu Xijun , Lu Zuhong
Published: September 2002

An approach has been developed for predicting the change of the aqueous phase pH due to the partition of amino acid substrates in aqueous–organic biphasic systems. In the model reaction of papain‐catalyzed synthesis of N‐benzyloxycarbonyl‐glycine‐L‐phenylalanine methyl ester (ZGPM) in an aqueous–ethyl acetate system, the effects of the initial aqueous phase pH and phase volume ratio on the final aqueous phase pH, and the change of the final aqueous phase pH during the course of ZGPM synthesis, are investigated. The results suggest that the approach is useful for selecting optimum reaction conditions for peptide synthesis not only in the aqueous–organic biphasic systems with free or immobilized enzymes but also with an immobilized enzyme in an organic solvent.

© 2001 Society of Chemical Industry
Non‐invasive detection of the metabolic burden on recombinant microorganisms during fermentation processes
Authors: Bachinger Th , Mandenius C ‐F , Striedner G , Clementschitsch F , Dürrschmid E , Cserjan‐Puschmann M , Doblhoff‐Dier O , Bayer K
Published: September 2002

Heterologous protein production is an important source of therapeutic products. Optimisation of such bioprocesses by adjustment of the expression rate of the heterologous protein to the biosynthetic capacity of the cell metabolism would benefit from an online method for monitoring the metabolic burden. In this study we evaluated the use of a chemical multi‐sensor array for this purpose. Fermentations with a recombinant Escherichia coli strain expressing human superoxide dismutase (rhSOD) were monitored by the sensor array. The results of isopropyl‐thiogalactopyranoside (IPTG)‐induced expression were compared with fermentations with a plasmid‐free strain. The overproduction of rhSOD, imposing a high metabolic burden on the plasmid‐carrying cells, was distinctly and reproducibly observed by the multi‐sensor array. The potential of this non‐invasive method of non‐specific metabolic burden monitoring is demonstrated by the results of the study.

© 2001 Society of Chemical Industry
Stabilisation of a ferro‐industry waste in various solid matrices
Authors: Potgieter J Herman , Potgieter Sanja S , Loubser Maggi , Kearsley Elsabé , Strydom Christien A
Published: September 2002

This paper describes various ways of stabilising a ferro‐vanadium waste. In each case a combination of the ferro‐vanadium waste together with fly ash was employed. The methods investigated ranged from physical encapsulation in different matrices to high temperature immobilisation in solid products.

© 2002 Society of Chemical Industry
Pure zeolite synthesis from silica extracted from coal fly ashes
Authors: Moreno Natàlia , Querol Xavier , Plana Felicià , Andres José Manuel , Janssen Maria , Nugteren Heng
Published: September 2002

Pure zeolites can be synthesised from silica extracted from fly ash by alkaline leaching. If the process is optimised the solid residue arising from this extraction may also contain a relatively high content of zeolitic material mixed with residual fly ash components. Both the pure and the impure zeolitic material have a high potential for application in waste‐water and flue gas‐cleaning technologies. The silica extraction potential of 23 European coal fly ashes covering most of the possible fly ash types is investigated in this study. Optimisation of leaching processes, by varying temperature, time and alkali/fly ash rates, permitted extraction yields up to 140 g of SiO2 per kg using a single step process, but the extraction yields may reach up to 210 g kg−1 by applying thermal pre‐treatments prior to the extraction. The solid residue arising from the silica extraction experiments shows a high NaP1 zeolite content. A high Si/Al ratio of the glass matrix, the occurrence of easily soluble silica phases in the original fly ash and a high reactive surface area were found to be the major parameters influencing silica extraction. High purity 4A and X zeolitic material was obtained by combining the silica extracts from the Meirama fly ash and a waste solution from the Al‐anodising industry. The results allowed conversion of the silica extraction yields to an equivalent 630 g of pure 4A–X zeolite per kg of fly ash with a cation exchange capacity of 4.7 meq g−1.

© 2002 Society of Chemical Industry
Zeolitic material synthesised from fly ash: use as cationic exchanger
Authors: Juan R , Hernández S , Querol X , Andrés J M , Moreno N
Published: September 2002

The potential use as a ‘once through’ cation exchanger of a zeolitic material (NaP1 zeolite as the main active component) synthesised from fly ash has been evaluated and compared with a commercial weak acid exchanger, Amberlite IRC‐50. The cationic exchange has been tested for different cations present in sewage: NH4+ (urban sewage) and Pb2+, Zn2+ and Cr3+ (waste from electrolytic baths). The NH4+ retention capacity was higher in the zeolite (0.7 meq g−1) than in Amberlite IRC‐50 (0.21 meq g−1). The retention capacities of metallic cations obtained for NaP1 zeolite (1.16 meq Pb2+ g−1, 1.45 meq Zn2+ g−1 and 1.57 meq Cr3+ g−1) were also higher than in Amberlite IRC‐50 (0.32 meq Pb2+ g−1, 0.25 meq Zn2+ g−1 and 0.35 meq Cr3+ g−1). When solutions containing all the metallic cations were used, lower retention capacities were obtained for both exchangers.

© 2002 Society of Chemical Industry
Novel products from combustion ash – legislative and marketing issues
Authors: Barnes D Ian
Published: September 2002

The production of novel products from combustion ash poses great technical challenges. Nevertheless, significant progress has been made in this area in recent years, and a number of novel products are at an advanced stage in the laboratory, or even at the pilot‐scale stage, en route to the marketplace. This paper sets out the issues that impact on the passage of novel products from research stage, through pilot stage, to the commercial marketplace. The importance of product standards is presented and discussed, and important legislation on health and safety and environmental matters considered. The roles of national and local taxation on the commercial prospects for new materials from ash are considered, and the barriers that can impede successful marketing of the products (eg customer perception) set out. The paper concludes with comments on how the market for ash products is developing and what remains to be done in the future.

© 2002 Society of Chemical Industry
Removal of heavy metals from fly ash and the impact on its quality
Authors: Nugteren Henk W , Janssen‐Jurkovícová Maria , Scarlett Brian
Published: September 2002

Most coal fly ashes currently produced in The Netherlands contain leachable trace elements in amounts higher than allowed by Dutch law for its free application as a granular building material. To improve their technical and environmental quality, these ashes were subjected to forced leaching using water, citrate, oxalate, EDTA and carbonate solutions. With water alone, the free lime and substantial amounts of Mo (30%), Se (20–40%) and SO42− (40–50%) are removed. Using the extraction agents, these percentages increase to 60–90% and in addition 15–20% Cr, V and Sb are removed. Most of the extraction agents used form stable complexes or compounds with Ca2+, thus prewashing with water followed by treatment with extraction agents resulted in higher removal and/or lower reagent consumption. The environmental quality of the washed fly ash was evaluated using the Dutch standard leaching test (NEN7343). Leachability of oxyanions decreased by a factor of 2–4 after washing with water and by between 2 and 18 after washing with extraction agents. However, combined washing did not further decrease leaching but in some cases caused increased leaching. Selection of the washing procedure thus depends on the subsequent application of the ash, that is whether low concentrations or low mobility of trace elements are required. Removing extractants and metals remaining in the moisture after filtration will further decrease leaching. For a feasible process reduction of reagent consumption and simple methods for process water recycling are needed.

© 2002 Society of Chemical Industry
Biological treatment of saline wastewaters from marine‐products processing factories by a fixed‐bed reactor
Authors: Gharsallah Neji , Khannous Lamia , Souissi Nabil , Nasri Moncef
Published: September 2002

Wastewaters generated by a factory processing marine products are characterized by high concentrations of organic compounds and salt constituents (>30 g dm−3). Biological treatment of these saline wastewaters in conventional systems usually results in low chemical oxygen demand (COD) removal efficiency, because of the plasmolysis of the organisms. In order to overcome this problem a specific flora was adapted to the wastewater from the fish‐processing industry by a gradual increase in salt concentrations. Biological treatment of this effluent was then studied in a continuous fixed biofilm reactor. Experiments were conducted at different organic loading rates (OLR), varying from 250 to 1000 mg COD dm−3 day−1. Under low OLR (250 mg COD dm−3 day−1), COD and total organic carbon (TOC) removal efficiencies were 92.5 and 95.4%, respectively. Thereafter, fluctuations in COD and TOC were observed during the experiment, provoked by the progressive increase of OLR and the nature of the wastewater introduced. High COD (87%) and TOC (99%) removal efficiencies were obtained at 1000 mg COD dm−3 day−1.

© 2002 Society of Chemical Industry
Novel lipase isolated from a Pseudomonas strain and its application in the synthesis of S(+)‐2‐O‐benzylglycerol‐1‐acetate
Authors: Kanwar L , Hazarika S , Goswami A , Dutta N N , Hazarika A K , Goswami Pranab
Published: September 2002

Isolation of a novel microbial lipase (EC 3.1.1.3) having specific catalytic activity for the synthesis of optically pure 2‐O‐benzylglycerol‐1‐acetate, the building block for the preparation of many β‐blockers, phospholipase A2 inhibitors and other biologically active compounds was the aim of this investigation. A Pseudomonas (strain G6), recently isolated from soil, produced an extracellular lipase. SDS–PAGE analysis showed that the lipase protein was a hexamer. The molecular weight of the sub‐units of the lipase protein were 10, 19, 29, 30, 47 and 53. The catalytic activity of the lipase was exploited for the synthesis of 2‐O‐benzylglycerol‐1‐acetate from 2‐O‐benzylglycerol through transesterification using vinyl acetate as acylating agent. High selectivity of the lipase towards the monoacetate product was demonstrated. A 97% enantiomeric excess (ee) of S(+)‐2‐O‐benzylglycerol‐1‐acetate was obtained when the reaction was carried out at room temperature with shaking. The lipase was highly active in anhydrous organic microenvironments and in non‐polar organic solvents with log P values above 2.5.

© 2002 Society of Chemical Industry
Effect of ozone and ozone/activated carbon treatments on genotoxic activity of naphthalenesulfonic acids
Authors: Rivera‐Utrilla J , Sánchez‐Polo M , Mondaca M A , Zaror C A
Published: September 2002

Naphthalenesulfonic compounds are widely used, mainly by the textile industry in the synthesis of azoic colorants. The presence of the sulfonic group is known to endow these compounds with high water‐solubility and low biodegradability, although its influence on their genotoxic activity is unknown. The use of energetic oxidants is recommended for the degradation of organic compounds which are refractory to biological treatment. Ozone and ozone/activated carbon have been proposed as the best alternatives to remove these compounds. The results showed that the more sulfonic groups there are on the aromatic ring of this family of contaminants, the lower is their genotoxic activity. All the compounds studied presented genotoxic activity at elevated concentrations. Ames test results indicate that DNA damage was produced by substitution of nitrogenated bases. The system based on the combined use of ozone and activated carbon was the most efficacious in the depuration of water containing these contaminants. This approach rapidly degraded the naphthalenesulfonic acids, eliminated their genotoxic activity and reduced their organic material content using low doses of ozone.

© 2002 Society of Chemical Industry
Removal of toxic metal ions from aqueous systems by biosorptive flotation
Authors: Zouboulis Anastasios I , Lazaridis Nick K , Matis Kostas A
Published: September 2002

Biosorptive flotation was used as a combined operation for the simultaneous abstraction of nickel, copper and zinc ions from aqueous streams. Laboratory‐scale batch experiments, as well as pilot‐scale continuous experiments, have been conducted. Grape stalks, a by‐product of the winery industry, were used as sorbent material. The experimental procedure consisted of two consecutive stages: (i) biosorption, and (ii) flotation. The possibility of reusing biomass, after appropriate elution, was also examined. The main parameters examined were biomass concentration, particle size of sorbent, surfactant concentration, pH and flocculation. Flotation removals, following laboratory‐scale experiments, were found to be in the order of 100, 85 and 70% for copper, zinc and nickel, respectively. In pilot‐scale experiments, biomass sorption capacities were determined as 25 for copper, 81 for zinc and 7 µmol dm−3 for nickel. The order of biomass affinity regarding the studied metals was Cu > Zn > Ni. Short retention time and high effectiveness suggest that biosorptive flotation is a promising treatment process for the removal of toxic metals from contaminated aqueous solutions.

© 2002 Society of Chemical Industry
Cationic lipids derived from glycine betaine promote efficient and non‐toxic gene transfection in cultured hepatocytes
Authors: Gilot David , Miramon Marie‐Laure , Benvegnu Thierry , Ferrieres Vincent , Loreal Olivier , Guguen‐Guillouzo Christiane , Plusquellec Daniel , Loyer Pascal
Published: September 2002

Background

The low efficiency and toxicity of transfection in a primary culture of hepatocytes using cationic lipids remains a limiting step to the study of gene function and the setting up of non‐viral gene therapy.

Methods

A novel class of cationic lipids (GBs) derived from natural glycine betaine compounds covalently linked to acyl chains by enzymatically hydrolysable peptide and ester bonds, a structure designed to reduce cytotoxicity, was used to improve transfection efficiency in a primary culture of rat hepatocytes. The relationship between lipid structure, lipoplex formulation and transfection efficiency was studied using six GBs (12‐14‐16, 22‐24‐26) varying in their spacer and acyl chains.

Results

GB12, characterized by short [(CH2)10] acyl chains and spacer, allowed plasmid uptake in all cells and reporter gene expression in up to 40% of hepatocytes with a low cytotoxicity, a much higher efficiency compared with transfections using other reagents including Fugene6™and Lipofectin™. We also showed that numerous cells accumulated high amounts of plasmids demonstrating that GB12 promoted a very efficient DNA transfer through plasma membrane leading to an increase in nuclear plasmid translocation, allowing a much higher gene expression. Moreover, GB12‐transfected hepatocytes survived to injection in normal livers and were found to express the LacZ reporter gene.

Conclusions

The non‐toxic GB12 formulation is a powerful vehicle for plasmid delivery in cultured hepatocytes with relevance in liver gene therapy. Copyright © 2002 John Wiley & Sons, Ltd.
Toward a racial abyss: Eugenics, Wickliffe Draper, and the origins of The Pioneer Fund
Authors: Kenny Michael G.
Published: September 2002

The Pioneer Fund was created in 1937 “to conduct or aid in conducting study and research into problems of heredity and eugenics…and problems of race betterment with special reference to the people of the United States.” The Fund was endowed by Colonel Wickliffe Preston Draper, a New England textile heir, and perpetuates his legacy through an active program of grants, some of the more controversial in aid of research on racial group differences. Those presently associated with the Fund maintain that it has made a substantial contribution to the behavioral and social sciences, but insider accounts of Pioneer's history oversimplify its past and smooth over its more tendentious elements. This article examines the social context and intellectual background to Pioneer's origins, with a focus on Col. Draper himself, his concerns about racial degeneration, and his relation to the eugenics movement. In conclusion, it evaluates the official history of the fund. © 2002 Wiley Periodicals, Inc.
Synthesis of [N‐methyl‐11C]mianserin: a tetracyclic, atypical antidepressant
Authors: Marthi K. , Bender D. , Smith D.F.
Published: September 2002

As part of our program to develop PET tracers for investigating monoaminergic processes in the brain, mianserin, a tetracyclic, atypical antidepressant, was selected as a candidate for labelling with 11C for in vivo evaluation. [N‐methyl‐11C]Mianserin was produced by the alkylation of N‐desmethyl mianserin with [11C]methyl iodide followed by HPLC purification and formulation. [N‐methyl‐11C]Mianserin was obtained with a radiochemical purity >93% in a 16% decay corrected radiochemical yield. For a typical production starting with 40 GBq [11C]CO2, 1.9 GBq [N‐methyl‐11C]mianserin was obtained as a formulated solution in a synthesis time of 35 min (counted from EOB). Copyright © 2001 John Wiley & Sons, Ltd.
The synthesis of labelled forms of cipemastat
Authors: Wiltshire H R , Prior K J , Dhesi J , Maile G
Published: September 2002

The development of the collagenase inhibitor, cipemastat (Ro 32‐3555), required the synthesis of both carbon‐14 labelled and deuteriated material for the measurement of the parent drug and drug‐related material in biological fluids. In addition, labelled metabolites were needed for both in vitro metabolism and analytical studies. This paper describes the synthesis of labelled forms of cipemastat and its amide (Ro 32‐4778) and glucuronide (Ro 32‐6414) metabolites. Copyright © 2001 John Wiley & Sons, Ltd.
Preparation of carbon‐14 labelled guazatine
Authors: Hudson Harry R. , Ismail Fatima , Powroznyk Lubomira
Published: September 2002

A method is described for small‐scale laboratory simulation of the industrial process for the manufacture of guazatine, an agrochemical fungicide comprising a mixture of guanidated di‐, tri‐, and poly‐amines derived from octamethylenediamine. The product has been prepared with carbon‐14 labelling of the terminal positions of the octamethylene chains. Copyright © 2001 John Wiley & Sons, Ltd.
Synthesis and 11C‐labelling of (E,E)‐1‐(3′,4′‐dihydroxystyryl)‐4‐(3′‐methoxy‐4′‐hydroxystyryl) benzene for PET imaging of amyloid deposits†
Authors: Wang Yanming , Mathis Chester A. , Huang Guo‐feng , Holt Daniel P. , Debnath Manik L. , Klunk William E.
Published: September 2002

Carboxylic acid derivatives of the amyloid‐binding dye Congo red do not enter the brain well and are thus unable to serve as in vivo amyloid‐imaging agents. A neutral amyloid probe, (E,E)‐1‐(3′,4′‐dihydroxystyryl)‐4‐(3′‐methoxy‐4′‐hydroxystyryl)benzene (3), devoid of any carboxylate groups has been designed and synthesized via a 12‐step reaction sequence with a total yield of 30%. The unsymmetric compound 3 has also been labelled with C‐11 via [11C]methyl iodide ([11C]CH3I) methylation of a symmetric 4,4′‐dimesyl protected precursor followed by deprotection. Preliminary evaluation indicated that compound 3 selectively stained plaques and neurofibrillary tangles in post‐mortem AD brain, and exhibited good binding affinity (Ki=38±8 nM) for Aβ(1–40) fibrils in vitro. In vivo pharmacokinetic studies indicated that [11C]3 exhibited higher brain uptake than its carboxylic acid analogs and good clearance from normal control mouse brain. [11C]3 also exhibited specific in vivo binding to pancreatic amyloid deposits in the NOR‐beta transgenic mouse model. These results justify further investigation of 3 and similar derivatives as surrogate markers for in vivo quantitation of amyloid deposits. Copyright © 2002 John Wiley & Sons, Ltd.
Kidney uptake of 186/188Re(V)‐DMSA is significantly reduced when the reducing agent is changed from stannous ion to metabisulfite
Authors: Kothari Kanchan , Satpati Drishty , Mukherjee Archana , Sarma H. D. , Venkatesh Meera , Pillai M. R. A.
Published: September 2002

We describe the work carried out on the preparation of 186/188Re(V)‐DMSA, which showed lower kidney retention, formulated by using metabisulfite as the reducing agent. The complex was prepared by reducing 186/188ReO4− (100 μg, 0.54 μM, ∼150 MBq) in the presence of Na2S2O5 (30 mg, 0.15 mM) and reacting with DMSA (10 mg, 0.05 mM) in saline at pH 3.5 and at 80°C for 1 h. The complex was characterized by TLC using acetone and saline as two different solvent systems. Reverse phase HPLC carried out using isocratic system with 90:10 water/acetonitrile mobile phase showed the existence of four species. Biodistribution studies were carried out in albino mice with 186/188Re(V)‐DMSA prepared via metabisulfite reductant [186/188Re(V)‐DMSA (MBS)] as well as stannous chloride reductant [186/188Re(V)‐DMSA (SnCl2)]. The distribution patterns were similar except for kidney uptake. Kidney retention in case of 186/188Re(V)‐DMSA (MBS) was lower [0.68 (±0.06)%/g] than that observed in case of 186/188Re(V)‐DMSA (SnCl2) [2.93(±0.93)%/g] after 24 h p.i. Though bone uptake was initially similar with both the preparations, there was substantial decrease in bone activity after 24 h p.i. with 186/188Re(V)‐DMSA (MBS). In vitro cell uptake studies were carried out with 186/188Re(V)‐DMSA (MBS), 186/188Re(V)‐DMSA (SnCl2) and 99mTc(V)‐DMSA using Ehrlich Ascites Tumor Cell Lines. Approximately 15% cell uptake was observed with 186/188Re(V)‐DMSA (MBS) as well as with 186/188Re(V)‐DMSA (SnCl2) and was comparable with that of 99mTc(V)‐DMSA (19%). Our studies indicate that 186/188Re(V)‐DMSA prepared by using metabisulfite as a reducing agent has potential for use in targeted radiotherapy of medullary thyroid carcinoma. Copyright © 2002 John Wiley & Sons, Ltd.
Water relaxation by SPM particles: Neglecting the magnetic anisotropy? A caveat
Authors: Roch Alain , Muller Robert N. , Gillis Pierre
Published: September 2002

Magnetometric and relaxometric data from SPM particles are revisited, leading to a double conclusion rather different from the original one: accounting for the anisotropy energy not only allows a considerable improvement of the fit of the data to theory, but it also invalidates the conclusion obtained from the high field data (without accounting for anisotropy) concerning an important reduction of the diffusion coefficient by the coating of the particles. J. Magn. Reson. Imaging 2001;14:94–96. © 2001 Wiley‐Liss, Inc.
Solvation of acylium fragment ions in electrospray ionization quadrupole ion trap and Fourier transform ion cyclotron resonance mass spectrometry
Authors: Guan Ziqiang , Liesch Jerrold M.
Published: September 2002

In electrospray ionization (ESI) quadrupole ion trap and Fourier transform ion cyclotron resonance mass spectrometry, certain fragment ions (e.g. acylium ions) generated either during the ion transportation process (in the source interface region) or in the ion trap are found to undergo ion–molecule reactions with ESI solvent molecules (water, acetonitrile and aliphatic alcohols) to form adduct species. These unexpected solvated fragment ions severely complicate the interpretation of mass spectrometic data. High‐resolution accurate mass measurements are important in establishing the elemental compositions of these adduct species and preventing erroneous data interpretation. Copyright © 2001 John Wiley & Sons, Ltd.
Multiphoton ionization and ab initio calculation of the hydrogen‐bonded clusters (C5H5N)n(NH3)m
Authors: Hu Yongjun , Lu Richang , Cai Yong , Wang Xiuyan
Published: September 2002

Multiphoton ionization of pyridine–ammonia binary clusters was studied using a time‐of‐flight mass spectrometer at 532 nm laser wavelength. The experimental results showed that the main products of the cluster ionization were the protonated cluster ions [(Py)n(NH3)mH]+. The proton transfer in the multiphoton ionization process is discussed. The hypervalent cluster ions [(Py)(NH3)nH2]+ (n = 1–4) were observed in the experiment and their formation mechanism, the geometric structures and the binding energies are discussed. The results of the theoretical calculation were in agreement with the experimental observations that the binary cluster ions [(Py)3NH4]+ and [(Py)4NH4]+ were the ‘magic number’ ions. Copyright © 2001 John Wiley & Sons, Ltd.
Sequence information, distinction and quantitation of C‐terminal leucine and isoleucine in ternary complexes of tripeptides with Cu(II) and 2,2′‐bipyridine
Authors: Vaisar Tomáš , Gatlin Christine L. , Rao Ramesh D. , Seymour Jennifer L. , Tureček František
Published: September 2002

Tripeptides form ternary complexes with Cu2+ and 2,2′‐bipyridine (bpy) that self‐assemble upon mixing the components in aqueous methanol solution. Electrospray ionization (ESI) of the complex solutions provides abundant singly charged [Cu(peptide − H)bpy]+ and doubly charged [Cu(peptide)bpy]2+ ions. Collision‐induced dissociation (CID) at low ion kinetic energies of several tripeptides, AGG, GGA, LGG, GGL, GGI, FGG, GGF, LGF, GLF, GFL, GYA and GAY, showed fragments that were indicative of the amino acid sequence in the peptide. In addition, CID of single and doubly charged complexes of isomeric tripeptides GGL and GGI provided unambiguous distinction of the isomeric leucine and isoleucine residues. Leucine peptides eliminated C3H7 radicals from the amino acid side‐chain whereas isoleucine eliminated C2H5 radicals. CID of gas‐phase doubly charged peptide complexes in a quadrupole ion trap produced a series of singly charged sequence fragments that following isolation and further CID furnished distinct fragments that allowed quantitation of leucine and isoleucine‐containing peptides in mixtures. Copyright © 2001 John Wiley & Sons, Ltd.
Equilenin‐2′‐deoxynucleoside adducts: analysis with nano‐liquid chromatography coupled to nano‐electrospray tandem mass spectrometry
Authors: Embrechts Jan , Lemière Filip , Dongen Walter Van , Esmans Eddy L.
Published: September 2002

The interaction of 4‐hydroxy metabolites of estrogens with DNA leads to the formation of DNA adducts. These adducts are believed to play an important role in the incidence of breast and endometrial cancer. In order to be able to analyze these adducts in in vivo samples a method based upon the coupling of miniaturized liquid chromatography (LC) to electrospray tandem mass spectrometry (ES‐MS/MS) was developed for the analysis of the adducts formed with 4‐hydroxyequilenin. In vitro synthesized adducts obtained by the reaction of 4‐hydroxyequilenin with the main 2′‐deoxynucleosides were separated on a Hypersyl C18 BDS nano‐HPLC column (15 cm × 75 µm i.d.) at a flow‐rate of 300 nl min−1 using gradient elution with CH3OH–0.2% CH3COOH in H2O. The column was coupled, in combination with a column switching system, to a nano‐electrospray interface. Analysis of the low‐ and high‐resolution low‐energy collision‐activated dissociation product ion spectra of normal and deuterated adducts supported earlier data demonstrating equilenin to form different isomeric adducts, except with thymidine, for which no adducts were found. The nano‐HPLC column‐switching ES‐MS system was tested for its sensitivity on a triple‐quadrupole instrument, and detection limits down to 197 fg in the single reaction monitoring mode were obtained for semi‐preparatively isolated equilenin–2′‐deoxyguanosine adduct. Copyright © 2001 John Wiley & Sons, Ltd.
MassKinetics: a theoretical model of mass spectra incorporating physical processes, reaction kinetics and mathematical descriptions
Authors: Drahos László , Vékey Károly
Published: September 2002

A theoretical framework and an accompanying computer program (MassKinetics, www.chemres.hu/ms/ masskinetics) is developed for describing reaction kinetics under statistical, but non‐equilibrium, conditions, i.e. those applying to mass spectrometry. In this model all the important physical processes influencing product distributions are considered: reactions, including the effects of acceleration, collisions and photon exchange. These processes occur simultaneously and are taken into account by the master equation approach. The system is described by (independent) product, kinetic energy and internal energy distributions, and the time development of these distributions is studied using transition probability functions. The product distribution at the end of the experiment corresponds to the mass spectrum. Individual elements in this scheme are mostly well known: internal energy‐dependent reaction rates are calculated by transition state theory (RRK or RRKM formalisms). In the course of collisions, energy transfer and other processes may occur (the latter usually resulting in the ‘loss’ of ion signal). Collisions are characterized by their probability and by energy transfer in a single collision. To describe single collisions, three collision models are used: long‐lived collision complexes, partially inelastic collisions and partially inelastic collisions with cooling. The latter type has been developed here, and is capable of accounting for cooling effects occurring in collision cascades. Descriptions of photon absorption and emission are well known in principle, and these are also taken into account, in addition to changes in kinetic energy due to external (electric) fields. These changes in the system occur simultaneously, and are described by master equations (a set of differential equations). The usual form of the master equation (taking into account reactions and collisional excitation) was extended to consider also radiative energy transfer, kinetic energy changes, energy partitioning and ion loss collisions. Initial results show that close to experimental accuracy can be obtained with MassKinetics, using few or no adjustable parameters. The model/program can be used to model almost all types of mass spectrometric experiments (e.g. MIKE, CID, SORI and resonant excitation). Note that it was designed for mass spectrometric applications, but can also be used to study reaction kinetics in other non‐equilibrium systems. Copyright © 2001 John Wiley & Sons, Ltd.
Matrix‐assisted laser desorption/ionization, fast atom bombardment and plasma desorption mass spectrometry of polyethylene glycol esters of (2‐benzothiazolon‐3‐yl)acetic acid
Authors: Mincheva Zoia , Hadjieva Petia , Kalcheva Veneta , Seraglia Roberta , Traldi Piero , Przybylski Michael
Published: September 2002

Fast atom bombardment (FAB), matrix‐assisted laser desorption/ionization time‐of‐flight (MALDI‐TOF) and plasma desorption (PD) mass spectra of newly synthesized polyethylene glycols (PEGs), (Mw 600–4000 Da) chemically modified with biologically active (2‐benzothiazolon‐3‐yl)acetyl end‐groups are described (products 1–6). The spectra were also used for the determination of the molecular mass characteristics (number average (Mn) and weight average (Mw) molecular masses) of the initial and modified PEGs. As expected, Mn and Mw of the modified samples are higher than those of the nonmodified samples. However, it is shown that molecular mass dispersity (determined by the comparison of the polydispersity indices (PDI = Mw/Mn) of both types of PEGs) essentially do not change during this modification. The FAB mass spectra, together with molecular species, show the presence of abundant [M + Na]+ ions of product 1 and [M + Na + H]+ species of 2 and 3, and [M + Na + 2H]+ of product 4. Two main series of fragment ions, derived from the cleavage of the ether bonds, are observed. The number fractions of the molecular adduct ions and fragment adduct ions, determined from the FAB and PD mass spectra of the modified PEGs, are compared. The MALDI‐TOF mass spectra of compounds 1–6 show the presence of two series of polymers. The most abundant peaks are due to [M + Na]+ and [M + K]+ ions originating from the polymers, in which the two terminal hydroxyl groups of PEGs are esterified with (2‐benzothiazolon‐3‐yl)acetic acid. The less abundant peaks are due to the monosubstituted polymers. Copyright © 2001 John Wiley & Sons, Ltd.
Capabilities of static TOF‐SIMS in the differentiation of first‐row transition metal oxides
Authors: Aubriet Frédéric , Poleunis Claude , Bertrand Patrick
Published: September 2002

Time‐of‐flight secondary ion mass spectrometry (TOF‐SIMS) analyses were performed on the first‐row transition metal oxides from scandium to zinc in positive and negative detection modes. The nature of the numerous MxOy+/− ionic species generated by 15 keV Ga+ primary ion bombardment allows the identification of a given metal–oxygen system. To identify the metal valence in the oxide under investigation, several procedures were investigated: the detection of specific and characteristic ions, the use of ion abundance ratios and the use of a valence model. Owing to their importance in many fields of materials science, each of these speciation methodologies was evaluated for the differentiation of vanadium, titanium, chromium, manganese, iron, cobalt and copper oxides. Trivalent–hexavalent chromium distinction was first intensely investigated because it really corresponds to a model system for inorganic speciation. For each series of metal oxides, the more pertinent speciation criteria were then systematically tested. The limitations of the proposed methodologies are discussed. Their use is made complicated when pollutants or a superficial oxide layer, with a stoichiometry different from that of the bulk, are present. Finally, thermodynamic considerations relative to the stability of the MxOy+/− ions may also modify the relationship between the analyzed oxide and the observed positive and negative secondary ion mass spectra. Copyright © 2001 John Wiley & Sons, Ltd.
Validated assay for quantification of oxcarbazepine and its active dihydro metabolite 10‐hydroxycarbazepine in plasma by atmospheric pressure chemical ionization liquid chromatography/mass spectrometry
Authors: Maurer Hans H. , Kratzsch Carsten , Weber Armin A. , Peters Frank T. , Kraemer Thomas
Published: September 2002

Oxcarbazepine (OX), a new antiepileptic, may lead to unwanted side‐effects or even life‐threatening intoxications after overdose. Therefore, a validated liquid chromatographic/mass spectrometric (LC/MS) assay was developed for the quantification of OX and its pharmacologically active dihydro metabolite (dihydrooxcarbazepine, DOX, often named 10‐hydroxycarbazepine). OX and DOX were extracted from plasma by the authors' standard liquid/liquid extraction and were separated on a Merck LiChroCART column with Superspher 60 RP Select B as the stationary phase. Gradient elution was performed using aqueous ammonium formate and acetonitrile. The compounds were quantified in the selected‐ion monitoring mode using atmospheric pressure chemical ionization electrospray LC/MS. The assay was fully validated. It was found to be selective. The calibration curves were linear from 0.1 to 50 mg l−1 for OX and DOX. Limits of quantification were 0.1 mg l−1 for OX and DOX. The absolute recoveries were between 60 and 86%. The accuracy and precision data were within the required limits. The analytes in frozen plasma samples were stable for at least 1 month. The method was successfully applied to several authentic plasma samples from patients treated or intoxicated with OX. The measured therapeutic plasma levels ranged from 1 to 2 mg l−1 for OX and from 10 to 40 mg l−1 for DOX. The validated LC/MS assay proved to be appropriate for quantification of OX and DOX in plasma for clinical toxicology and therapeutic drug monitoring purposes. The assay is part of a general analysis procedure for the isolation, separation and quantification of various drugs and for their full‐scan screening and identification. Copyright © 2002 John Wiley & Sons, Ltd.
Mass spectrometric characterization of substituted 2‐thiazolin‐4‐one derivatives
Authors: Giorgi Gianluca , Salvini Laura , Attanasi Orazio A. , Filippone Paolino , Santeusanio Stefania
Published: September 2002

Electron ionization mass spectrometry was used for the structural characterization of substituted 2‐thiazolin‐4‐one derivatives in the gas phase. The compounds follow common fragmentation pathways, producing ions whose abundances are dependent on the chemical nature of the substituent at position 2. Collision‐induced dissociation tandem mass spectrometric experiments, carried out on both molecular ions and fragment ions produced in the source, allowed the elucidation of gas‐phase decompositions. The presence of tautomeric forms is suggested for some ionic species. Rapid identification of a primary or secondary amine moiety at position 2 of the thiazoline ring can be achieved by the detection of characteristic fragmentations occurring both in the ion source and under the collision‐induced dissociation regime. Copyright © 2002 John Wiley & Sons, Ltd.
Decomposition of multicomponent mass spectra using Bayesian probability theory
Authors: Kang H. D. , Preuss R. , Schwarz‐Selinger T. , Dose V.
Published: September 2002

We present a method for the decomposition of the mass spectra of mixed gases using Bayesian probability theory. The method works without any calibration measurement and therefore applies also to the analysis of spectra containing unstable species. For the example of mixtures of three different hydrocarbon gases the algorithm provides concentrations and cracking coefficients of each mixture component and also their confidence intervals. The amount of information needed to obtain reliable results and its relation to the accuracy of our analysis are discussed. Copyright © 2002 John Wiley & Sons, Ltd.
Qualitative characterization of biomolecular zinc complexes by collisionally induced dissociation
Authors: Afonso Carlos , Hathout Yetrib , Fenselau Catherine
Published: September 2002

Nanospray and collisionally induced dissociation (CID) on a quadrupole/time‐of‐flight mass spectrometer were used to examine the complexes formed between the zinc ion binding protein metallothionein and a series of peptides related to glutathione. The objective of the study was to determine if CID could be used to distinguish complexes that are stabilized by co‐chelation of a zinc ion from non‐covalent complexes that were formed in some other way. Differences in the collision energy required for dissociation and, more importantly, differences in the distribution of zinc ions between the pairs of dissociation products suggest that mass spectrometry can provide qualitative information about the bimolecular chelation of metal ions. The potential application to zinc chelates is particularly important, since biological chelates do not provide signals directly detectable by NMR, Mössbauer or other spectroscopies. The observations reported here also allowed a molecular mechanism to be proposed to explain the differences observed by others in the physiological interactions of reduced and oxidized glutathione with metallothionein. Copyright © 2002 John Wiley & Sons, Ltd.
Trend of hepatitis B virus infection in freshmen classes at two high schools in Hualien, Taiwan from 1991 to 1999
Authors: Lin Hans Hsienhong , Lin Sherry S.J. , Chiang Yu‐Ming , Wang Li‐Yu , Huang Lu‐Chin , Huang Shi‐Che , Liu Tso‐Tsa
Published: September 2002

Taiwan is an endemic area of hepatitis B virus (HBV) infection. A nationwide mass vaccination program to prevent HBV infection was started in 1985. Perinatal and horizontal transmission of HBV decreased substantially after the launching of this program. However, the influence of this program on children born before 1985 has not been studied. From 1991 to 1999, annual surveys of hepatitis B virus surface antigen (HBsAg) and antibody (anti‐HBs) were carried out in freshmen at two high schools in Hualien, Taiwan. The average age was 16 years old. Although these students were born 2–10 years after the start of the national HBV vaccination program, there is a significant trend of decreasing HBsAg carrier rate (from 21.0% to 10.5% in males and 14.3% to 4.7% in females) and increasing anti‐HBs rate (from 56.6% to 67.8% in males and 70.3% to 75.9% in females) over the 9 years. With yearly comparison, the carrier rate of HBsAg started to show significant decrease since 1994, while the anti‐HBs began to rise significantly after 1996, especially in male students. The HBsAg carrier rate in male students was significantly higher, while the anti‐HBs rate was significantly lower, than that in female students in most of the years. It is concluded that the effect of HBV vaccination also reduced horizontal transmission of HBV to children born up to 7 years before the start of the program. J. Med. Virol. 67:472–476, 2002. © 2002 Wiley‐Liss, Inc.
Preponderance of hepatitis B virus genotype B contributes to a better prognosis of chronic HBV infection in Okinawa, Japan
Authors: Sakugawa Hiroshi , Nakasone Hiroki , Nakayoshi Tomofumi , Orito Etsuro , Mizokami Masashi , Yamashiro Tsuyoshi , Maeshiro Tatsuji , Kinjo Fukunori , Saito Atsushi , Miyagi Yasuhiro
Published: September 2002

The present study was designed to examine the distribution of hepatitis B virus (HBV) genotypes among patients at various stages of chronic liver disease type B in Okinawa Prefecture, Japan, where the prevalence of hepatitis B surface antigen is the highest in Japan despite the lowest mortality rate from primary liver cancer. Serum samples from 227 HBV carriers were determined for HBV genotype by polymerase chain reaction (PCR)‐restriction fragment length polymorphism. Five of 227 sera were negative for HBV DNA by nested PCR and were excluded from the genotype analysis. Genotype B was predominant in asymptomatic carriers (45/67, 67%), whereas genotype C was predominant in chronic liver disease: 49% (50/103) in patients with chronic hepatitis, 63% (20/32) in patients with cirrhosis, and 60% (12/20) in patients with hepatocellular carcinoma. The distribution of genotype B decreased with increasing liver disease severity. However, this tendency was seen among patients aged less than 50 years old, whereas the prevalence of genotype B was similar among carriers with various liver diseases who were older than age 50. In conclusion, HBV genotype B was prevalent and less frequent among patients with advanced liver disease, particularly in patients aged less than 50 years. These findings suggest that the preponderance of genotype B is responsible for the low mortality rate of primary liver cancer associated with HBV seen in Okinawa Prefecture, despite having the highest HBV carrier rate in Japanese. J. Med. Virol. 67:484–489, 2002. © 2002 Wiley‐Liss, Inc.
Hepatitis C virus–Epstein‐barr virus interaction in patients with AIDS
Authors: Challine Dominique , Buisson Marlyse , Cadilhac Michel , Germanidis Georgios , Joab Irene , Eliaszewicz Muriel , Caumes Eric , Flahault Antoine , Fillet Anne‐Marie , Pawlotsky Jean‐Michel , Seigneurin Jean‐Marie
Published: September 2002

Immortalization of B cells by Epstein‐Barr virus (EBV) and their subsequent proliferation leads to B‐cell non‐Hodgkin's lymphoma in immunocompromised patients. The role of hepatitis C virus (HCV) in B‐cell non‐Hodgkin's lymphoma has recently been raised, and an interaction between HCV and EBV is supported by recent in vitro experiments. The aim of this study was to investigate in vivo interactions between HCV and EBV in patients with AIDS, i.e., patients exposed to the risk of EBV‐related B‐cell non‐Hodgkin's lymphoma. A total of 135 patients were prospectively studied. Serological and molecular markers of HCV, EBV, and human immunodeficiency virus (HIV) infection were sought. All the patients harbored latent EBV infection, and 20% had detectable HCV RNA in serum. No significant relationship was found between HIV, HCV, and EBV viral load in peripheral blood mononuclear cells or plasma. There was no difference between anti‐HCV‐positive and ‐negative patients or between HCV RNA‐positive and ‐negative patients with regard to the prevalence of EBV markers, especially EBV replication markers. The presence of EBV replication markers was not related to HCV RNA seropositivity or to HCV viral load. Five patients subsequently developed B‐cell non‐Hodgkin's lymphoma, none of whom had markers of EBV or HCV replication. These results argue against an in vivo interaction between HCV and EBV in patients with AIDS, and against a role of HCV infection in the occurrence of B‐cell non‐Hodgkin's lymphoma in these patients. J. Med. Virol. 67:510–515, 2002. © 2002 Wiley‐Liss, Inc.
Prolonged shedding of rotavirus in a geriatric inpatient
Authors: Mori Isamu , Matsumoto Kazuo , Sugimoto Kazunori , Kimura Makiko , Daimon Nagomu , Yokochi Takashi , Kimura Yoshinobu
Published: September 2002

This study concerns a nosocomial rotaviral infection of a geriatric patient with clinical symptoms of acute gastroenteritis. The virological diagnosis was based on the detection of rotaviral antigens using a Rota kit, viral genome RNA by reverse transcription‐polymerase chain reaction method, and viral particles by electron microscopy in the stool samples. Prolonged rotaviral shedding was suggested to be due to impaired natural killer cell activity, possibly together with deficiency of specific local immune response of the patient. J. Med. Virol. 67:613–615, 2002. © 2002 Wiley‐Liss, Inc.
Direct cell–cell interactions control apoptosis and oligodendrocyte marker expression of neuroepithelial cells
Authors: Hugnot J.P. , Mellodew K. , Pilcher H. , Uwanogho D. , Price J. , Sinden J.D.
Published: September 2002

During brain development, the neuroepithelium generates neurons and glial cells. Proliferation and differentiation of neuroepithelial cells are controlled by a complex combination of secreted factors and more intrinsic or local mechanisms, such as lateral inhibition and asymmetric division. To obtain further insights into the signals governing neuroepithelial cell fate, we used the immortomouse to derive conditionally immortalised cell lines from mouse E10 neuroepithelium. We isolated a nestin‐positive basic fibroblast growth factor (bFGF)‐responsive cell line (SVE10‐23) which mostly differentiate into astrocytes when cocultured with primary cortical cells. We found that, by simply lowering the cell density, SVE10‐23 cells embarked on oligodendrocytic differentiation as indicated by the strong expression of galactocerebroside C and 2′3′‐cyclic nucleotide 3′‐phosphodiesterase. Apoptosis accompanied the differentiation, and all cells died within 1 week. We present here evidence that direct interactions between cells are the main mechanism regulating this oligodendrocytic differentiation. We demonstrate that SVE10‐23 cells contact or proximity inhibit their differentiation, prevent apoptosis, and promote their proliferation. Similarly, others nestin‐positive precursor cell lines and nonimmortalised bFGF‐grown E10 cells were found to spontaneously differentiate at low density, thus generalising the idea that neural precursor fate is regulated by direct cell–cell interactions. The SVE10‐23 cell line provides a valuable tool with which to study further the molecular components implicated in this mode of regulation. J. Neurosci. Res. 65:195–207, 2001. © 2001 Wiley‐Liss, Inc.