bluuebunny/crossref_metadata_2025 huggingface dataset:
Structural Effects of Group VI Metal Tricarbonyl Binding to Benzenoid Rings: Interruption of Conjugation or Enhanced Aromaticity?
Authors: Baldridge Kim K. , Nambu Mitch , Siegel Jay S.
Published: June 2003

The effect of tricarbonyl (group VI metal) complexation on the geometric aromatic character of benzenoid rings is studied as a function of bond‐length alternation (localization) in the parent arene. Good agreement between theory and experiment is established for (η6‐benzene) tricarbonylchromium, ‐molybdenum, and ‐tungsten. It is found that, whereas the electrons of benzene become slightly more localized upon tricarbonyl metal complexation, those of ‘cyclohexatriene' mimics, like in‐starphenylene, become more delocalized. A combination of ab initio quantum‐mechanical and high‐accuracy X‐ray methods leads to a linear structurestructure correlation between the free and metal‐bound arene bond‐alternation geometry. In all cases, the average bond length in the arene increases upon complexation. The computational observation that the average bond length increases more in benzene complexes than in in‐starphenylene implies stronger back bonding in the benzene complexes and coincides with the experimental observation that more‐delocalized arenes form thermodynamically favored complexes. The rotational barriers about the tricarbonylmetal‐to‐arene axis were computed for 1‐Cr, 1‐Mo, and 1‐W as well as for 5‐Cr, 5‐Mo, and 5‐W. Barriers for the former group are characteristically low, almost negligible (0.05 kcal/mol for 1‐Cr; 0.01 kcal/mol for 1‐Mo; 0.27 kcal/mol for 1‐W), whereas for the latter group they are substantial (11.2 kcal/mol for 5‐Cr; 15.2 kcal/mol for 5‐Mo; 13.6 kcal/mol for 5‐W). The higher barriers found in 5‐M compounds are consistent with previous findings.
Helicity‐Encoded Molecular Strands: Efficient Access by the Hydrazone Route and Structural Features
Authors: Schmitt Jean‐Louis , Stadler Adrian‐Mihail , Kyritsakas Nathalie , Lehn Jean‐Marie
Published: June 2003

Control over the folding of molecular strands may be achieved by appropriate choice of the constituting subunits, in particular for chains of specific heterocycles such as sequences of directly connected pyridine (py) and pyrimidine (pym) rings, which are known to fold into extended helical structures. Since the hydrazone (hyz) group represents an isomorphic analogue of a py site, the condensation of hydrazine and carboxaldehyde derivatives of pym offers a very efficient approach to strands incorporating hyz instead of py units and constituted by sequences of alternating hyz and pym groups. A series of such strands of different lengths, up to ten hyz units, i.e., 1–7, were synthesized. Their spectral properties indicate that they fold indeed into helical shapes. Extensive characterization was performed in solution by 1HNMR spectroscopy and in the solid state by determination of the crystal structures of eight such strands. They all display the expected helical geometry with up to 3 1/3 turns and direct stacking contacts. The efficiency and flexibility of the synthetic approach as well as its wide potential for generation of diversity through lateral decoration make the (hyzpym) subunit a particularly attractive helicity codon.
Getting More out of Crystal‐Structure Analyses
Authors: Bürgi Hans‐Beat , Capelli Silvia C.
Published: June 2003

Motion and disorder in the crystal structures of benzene, (D6)benzene, and the clathrate C60⋅(HQ)3 (HQ=hydroquinone=benzene‐1,4‐diol) are studied. The observed temperature evolution of their atomic displacement parameters (ADPs) is analyzed in terms of a physical model that explicitly accounts for effects of temperature. The major part of the ADPs of (D6)benzene is explained by rigid‐body normal modes. The small but significant fraction that remains is shown to be due to zero‐point intramolecular motion. Comparison of the ADPs of D‐ and H‐isotopomers of benzene confirms the expected isotopic relationship. These findings, which leave no room for disorder between two Kekulé structures, corroborate the validity of the physical model. An analogous treatment of the ADPs of the hydroquinone part of the clathrate compound reveals a distinctive disposition of displacements related neither to rigid‐body nor to zero‐point motion. The pattern is interpreted nearly quantitatively in terms of orientational and positional disorder of the hydroquinone molecule amounting to a few degrees and hundredths of an Ångström, respectively. The model of disorder accounts for unusual bond angles in the average structure and suggests a chemically sensible pattern of locally ordered H‐bonds.
The RE M E Phases
Authors: Bojin Mihaela D. , Hoffmann Roald
Published: June 2003

There are more than 2000 compounds with RE/M/E 1 : 1 : 1 stoichiometry, where RE is a rare earth, actinide, or from groups 1–4, E is a late transition metal from groups 8–12, and E belongs to groups 13–15. In the first paper of a series, we describe the primary structural characteristics of this large class of compounds, focusing on the geometries and bonding in the [ME]n− anionic sublattices. We start with a detailed description of the EuAuSn lattice, by emphasizing its essential building blocks and the symmetry operations connecting them, in order to set up a way of describing systematically the geometric features of other RE M E frameworks. Nearly all these phases have eclipsed hexagonal layered arrangements (with only ME bonds within these slabs) in the ME sublattice. In most cases, stacking the puckered layers in the third dimension gives rise to ME, MM, or EE bonds, alternating in certain patterns. We point to several interesting sets of RE M E compounds, of like structure, but whose electron counts vary significantly. The structures of nonlayered networks and their most‐common electron counts are also introduced.
The RE M E Phases
Authors: Bojin Mihaela D. , Hoffmann Roald
Published: June 2003

In the second contribution on the RE M E phases, we enumerate the distinct networks resulting from the stacking in an eclipsed fashion of graphitic and puckered layers. Specifically, we derive all the distinct hypothetical lattices for up to N=7 layers per unit cell for planar (graphitic) sheets, and up to N=10 for slightly puckered layers. For the networks with slightly puckered layers, there can be only an even number of layers/unit cell, N. Additionally, we formulate an empirical rule for network stability: the structure should have either a mirror plane or a twin operation (mirror plane, followed by a color change) bisecting it half‐way up the stacking axis. Using these simple principles, from the original multitude of 2N−1 structures for a given N, we are able to significantly narrow down the number of potential combinations. Thus, for N=2, we find two nets, for N=4, one, for N=6, two, for N=8, there are no such viable arrangements, and for N=10, we exclude all but two distinct lattices. We sketch further guidelines to continue the enumeration for higher Ns. We also propose an ‘overlapping' Aufbau, by which more‐complex structures are derived from the smaller, basic ones. In the last part, we analyze the eclipsed stacking of diamond‐type layers; the resulting networks are analogous (in sequencing) to those determined for slightly puckered sheets. The networks formed from staggered diamond‐type layers are briefly discussed in the context of the related SiC polytypes.
Any Scalene Triangle Is the Most Chiral Triangle
Authors: Rassat André , Fowler Patrick W.
Published: June 2003

The shape space of all possible triangles is represented by a triangular diagram, an analogue of the phase diagram for ternary mixtures. Each point of its interior corresponds to the angle set of a pair of (2D) enantiomeric physical triangles and, with appropriate conventions, to just one member of the pair. Points on median lines represent achiral triangles, those on sides represent degenerate chiral triangles, and those on vertices achiral degenerate linear triangles. A chirality index for triangles must vanish on these lines, but nowhere else within the six compartments of the diagram, and should alternate in sign between them. The archetype is the lowest A2‐symmetric eigenfunction of the Schrödinger equation for the particle confined to an equilateral triangular box. Within the constraints, the extrema of an acceptable function may be pushed onto any D3h‐symmetric hexagonal set of points in the diagram, thereby verifying a conjecture of Dunitz that any scalene triangle is the most‐chiral triangle for some legal 2D‐chirality index.
Face alignment using view‐based direct appearance models
Authors: Yan Shuicheng , Hou Xinwen , Li Stan Z. , Zhang Hongjiang , Cheng Qiansheng
Published: June 2003

Accurate face alignment is the prerequisite for many computer vision problems, such as face recognition, synthesis and 3D face modeling. In this article, a novel appearance model, called direct appearance model (DAM), is proposed and its extended view‐based models are applied for multiview face alignment. Similar to the active appearance model (AAM), DAM also makes ingenious use of both shape and texture constraints; however, it does not combine them as in AAM; texture information is used directly to predict the shape and estimate the position and appearance (hence the name DAM). The way that DAM models shapes and textures has the following advantages as compared with AAM: (1) DAM subspaces include admissible appearances previously unseen in AAM, (2) it can converge more quickly and has higher accuracy, and (3) the memory requirement is cut down to a large extent. Extensive experiments are presented to evaluate the DAM alignment in comparison with AAM. © 2003 Wiley Periodicals, Inc. Int J Imaging Syst Technol 13: 106–112, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ima.10039
How we detect a face: A survey of psychological evidence
Authors: Lewis Michael B. , Ellis Hadyn D.
Published: June 2003

Scientists strive to build systems than can detect and recognize faces. One such system already exists: the human brain. How this system operates, however, is far from being fully understood. In this article, we review the psychological evidence regarding the process of face detection in particular. Evidence is collated from a variety of face‐processing tasks including stimulus detection; face categorization, visual search, first saccade analysis, and face detection itself. Together, the evidence points towards a multistage‐processing model of face detection. These stages involve preattentive processing, template fitting, and template evaluation. Comparisons are made with automatic face‐detection systems. © 2003 Wiley Periodicals, Inc. Int J Imaging Syst Technol 13, 3–7, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ima.10040
Modeling and animation of individualized faces for 3D facial expression synthesis
Authors: Zhang Yu , Prakash Edmond C. , Sung Eric
Published: June 2003

This article presents new methods for realistic and fast 3D facial expression synthesis based on an individualized face model constructed from the anatomical perspective. The face model has a 3D structure of anatomically motivated facial skin, muscles, and skull. We start from a highly accurate facial mesh reconstructed from the individual face measurements. By taking as input a collection of reflectance images covering the face, the view‐based texture blending method automatically generates a comprehensive texture map for photorealistic rendering. Based on the reconstructed facial mesh, a deformable multilayer skin model is developed to simulate the dynamic behavior of the skin by taking into account the nonlinear stress‐strain relationship and incompressibility of the skin. We develop a muscle modeling process that includes three kinds of force‐based facial muscle model to simulate facial muscle contraction. The 3D face model incorporates a skull structure which extends the scope of facial motion, facilitates facial muscle construction and constrains skin deformation. Based on the facial action coding system, various facial expressions are synthesized by the contraction of a set of facial muscles. Lagrangian mechanics governs the dynamics, dictating the deformation of facial skin in response to the contraction of muscles. For computational efficiency, we devise an adaptive computation algorithm for the numerical simulation. It uses either a semi‐implicit integration scheme or a quasi‐static solver to compute the relaxation of the facial mesh by traversing the designed data structures in a breadth‐first order. The resulting system enables us to construct realistic face models of living humans and to synthesize facial expressions in real time. © 2003 Wiley Periodicals, Inc. Int J Imaging Syst Technol 13: 42–64, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ima.10041
Face tracking for model‐based coding and face animation
Authors: Ahlberg Jörgen , Forchheimer Robert
Published: June 2003

We present a face and facial feature tracking system able to extract animation parameters describing the motion and articulation of a human face in real‐time on consumer hardware. The system is based on a statistical model of face appearance and a search algorithm for adapting the model to an image. Speed and robustness is discussed, and the system evaluated in terms of accuracy. © 2003 Wiley Periodicals, Inc. Int J Imaging Syst Technol 13: 8–22, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ima.10042
Synthetic faces: Analysis and applications
Authors: Kshirsagar Sumedha , Garchery Stephane , Sannier Gael , Magnenat‐Thalmann Nadia
Published: June 2003

Facial animation has been a topic of intensive research for more than three decades. Still, designing realistic facial animations remains to be a challenging task. Several models and tools have been developed so far to automate the design of faces and facial animations synchronized with speech, emotions, and gestures. In this article, we take a brief overview of the existing parameterized facial animation systems. We then turn our attention to facial expression analysis, which we believe is the key to improving realism in animated faces. We report the results of our research regarding the analysis of the facial motion capture data. We use an optical tracking system that extracts the 3D positions of markers attached at specific feature point locations. We capture the movements of these face markers for a talking person. We then form a vector space representation by using the principal component analysis of this data. We call this space “expression and viseme space.” As a result, we propose a new parameter space for sculpting facial expressions for synthetic faces. Such a representation not only offers insight into improving realism of animated faces, but also gives a new way of generating convincing speech animation and blending between several expressions. Expressive facial animation finds a variety of applications ranging from virtual environments to entertainment and games. With the advances in Internet technology, the development of online sales assistants, Web navigation aides and Web‐based interactive tutors is promising than ever before. We overview the recent advances in the field of facial animation on the Web, with a detailed look at the requirements for Web‐based facial animation systems and various applications. © 2003 Wiley Periodicals, Inc. Int J Imaging Syst Technol 13: 65–73, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ima.10043
Audiovisual localization of multiple speakers in a video teleconferencing setting
Authors: Kapralos Bill , Jenkin Michael R. M. , Milios Evangelos
Published: June 2003

Attending to multiple speakers in a video teleconferencing setting is a complex task. From a visual point of view, multiple speakers can occur at different locations and present radically different appearances. From an audio point of view, multiple speakers may be speaking at the same time, and background noise may make it difficult to localize sound sources without somea prioriestimate of the sound source locations. This article presents a novel sensor and corresponding sensing algorithms to address the task of attending, simultaneously, to multiple speakers for video teleconferencing. A panoramic visual sensor is used to capture a 360° view of the speakers in the environment and from this view potential speakers are identified via a color histogram approach. A directional audio system based on beamforming is then used to confirm potential speakers and attend to them. Experimental evaluation of the sensor and its algorithms are presented including sample performance of the entire system in a teleconferencing setting. © 2003 Wiley Periodicals, Inc. Int J Imaging Syst Technol 13: 95–105, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ima.10045
Face as an index: Knowing who is who using a PDA
Authors: Yang Jie , Chen Xilin , Kunz William , Kundra Harsh
Published: June 2003

In this article, we present a PDA‐based system for extending human memory or/and information retrieval using a human face as the lookup index. The system can help a user to remember names of people whom he/she has met before and find useful information, such as names and research interests, about people whom he/she is interested in talking to. The system uses a captured face image as the lookup index to retrieve information from some available resource such as departmental directory, web sites, personal homepages, etc. We describe the development of a PDA‐based face recognition system and introduce algorithms for image preprocessing to enhance the quality of the image by sharpening focus and normalizing both lighting condition and head rotation. We use a unified LDA/PCA algorithm for face recognition. We address design issues of the interface to assist in visualization and comprehension of retrieved information. We present user study and experiment results to demonstrate the feasibility of the proposed system. © 2003 Wiley Periodicals, Inc. Int J Imaging Syst Technol 13: 33–41, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ima.10046
Face recognition based on face‐specific subspace
Authors: Shan Shiguang , Gao Wen , Zhao Debin
Published: June 2003

In this article, we present an individual appearance model based method, named face‐specific subspace (FSS), for recognizing human faces under variation in lighting, expression, and viewpoint. This method derives from the traditional Eigenface but differs from it in essence. In Eigenface, each face image is represented as a point in a low‐dimensional face subspace shared byallfaces; however, the experiments conducted show one of the demerits of such a strategy: it fails to accurately represent the most discriminanting features of a specific face. Therefore, we propose to model each face with one individual face subspace, named Face‐Specific Subspace. Distance from the face‐specific subspace, that is, the reconstruction error, is then exploited as the similarity measurement for identification. Furthermore, to enable the proposed approach to solve the single example problem, a technique to derive multisamples from one single example is further developed. Extensive experiments on several academic databases show that our method significantly outperforms Eigenface and template matching, which intensively indicates its robustness under variation in illumination, expression, and viewpoint. © 2003 Wiley Periodicals, Inc. Int J Imaging Syst Technol 13: 23–32, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ima.10047
Erratum: Pyramid‐based super‐resolution of the undersampled and subpixel image sequence, vol. 12, no. 6, pp. 254–263, 2002
Authors: Lu Yao , Inamura Minoru
Published: June 2003

The original article to which this Erratum refers was published in International Journal of Imaging Systems and Technology (2002) 12(6) 254–263

An error was made in the spelling of the second author's name for the online version of the above article. Please note the correct spelling should be as above: Inamura. We apologize to the author for this error.
Putative role of proteolysis and inﬂammatory response in the toxicity of nerve and blister chemical warfare agents: implications for multi‐threat medical countermeasures
Authors: Cowan F. M. , Broomﬁeld C. A. , Lenz D. E. , Smith W. J.
Published: June 2003

Despite the contrasts in chemistry and toxicity, for blister and nerve chemical warfare agents there may be some analogous proteolytic and inﬂammatory mediators and pathological pathways that can be pharmacological targets for a single‐drug multi‐threat medical countermeasure. The dermal–epidermal separation caused by proteases and bullous diseases compared with that observed following exposure to the blister agent sulfur mustard (2,2′‐dichlorodiethyl sulﬁde) has fostered the hypothesis that sulfur mustard vesication involves proteolysis and inﬂammation. In conjunction with the paramount toxicological event of cholinergic crisis that causes acute toxicity and precipitates neuronal degeneration, both anaphylactoid reactions and pathological proteolytic activity have been reported in nerve‐agent‐intoxicated animals. Two classes of drugs already have demonstrated multi‐threat activity for both nerve and blister agents. Serine protease inhibitors can prolong the survival of animals intoxicated with the nerve agent soman and can also protect against vesication caused by the blister agent sulfur mustard. Poly (ADP‐ribose) polymerase (PARP) inhibitors can reduce both soman‐induced neuronal degeneration and sulfur‐mustard‐induced epidermal necrosis. Protease and PARP inhibitors, like many of the other countermeasures for blister and nerve agents, have potent primary or secondary anti‐inﬂammatory pharmacology. Accordingly, we hypothesize that drugs with anti‐inﬂammatory actions against either nerve or blister agent might also display multi‐threat efﬁcacy for the inﬂammatory pathogenesis of both classes of chemical warfare agent. Published in 2003 by John Wiley & Sons, Ltd.
Therapy and prophylaxis of inhaled biological toxins
Authors: Paddle Brian M.
Published: June 2003

This review highlights the current lack of therapeutic and prophylactic treatments for use against inhaled biological toxins, especially those considered as potential biological warfare (BW) or terrorist threats. Although vaccine development remains a priority, the use of rapidly deployable adjunctive therapeutic or prophylactic drugs could be life‐saving in severe cases of intoxication or where vaccination has not been possible or immunity not established. The current lack of such drugs is due to many factors. Thus, methods involving molecular modelling are limited by the extent to which the cellular receptor sites and mode of action and structure of a toxin need to be known. There is also our general lack of knowledge of what effect individual toxins will have when inhaled into the lungs — whether and to what extent the action will be cell speciﬁc and cytotoxic or rather an acute inﬂammatory response requiring the use of immunomodulators.

 Possible sources of speciﬁc high‐afﬁnity toxin antagonists being investigated include monoclonal antibodies, selected oligonucleotides (aptamers) and derivatized dendritic polymers (dendrimers). The initial selection of suitable agents of these kinds can be made using cytotoxicity assays involving cultured normal human lung cells and a range of suitable indicators. The possibility that a mixture of selected antibody, aptamer or dendrimer‐based materials for one or more toxins could be delivered simultaneously as injections or as inhaled aerosol sprays should be investigated. © Crown Copyright 2003. Reproduced with the permission of Her Majesty's Stationery Office. Published by John Wiley & Sons, Ltd.
Toxicity of cholesterol oxidation products to Caco‐2 and HepG2 cells: modulatory effects of α‐ and γ‐tocopherol
Authors: O'Sullivan A. J. , O'Callaghan Y. C. , Woods J. A. , O'Brien N. M.
Published: June 2003

Cholesterol can be oxidized to form a variety of cholesterol oxidation products also known as oxysterols. The aims of the present study were to compare the cytotoxic effects of four oxysterols, namely 25‐hydroxycholesterol (25‐OHC), 7β‐hydroxycholesterol (7β‐OHC), cholesterol‐5β,6β‐epoxide (β‐epox) and cholesterol‐5α,6α‐epoxide (α‐epox), in two human cell culture models. Further, the ability of 10 and 100 µm α‐ and γ‐tocopherol (α‐TOC and γ‐TOC, respectively) to protect against oxysterol‐induced cytotoxicity was also assessed. Human colonic adenocarcinoma Caco‐2 and human hepatoma HepG2 cells were supplemented with increasing concentrations of 25‐OHC, 7β‐OHC, β‐epox and α‐epox (0–25 µg ml−1) for 24, 48 or 96 h. Following 24‐h and 48‐h exposure, test media were replaced with normal growth media and the cells were maintained for 72 and 48 h, respectively. The 96‐h exposure represented a constant challenge to the cells. Cytotoxicity was assessed using the neutral red uptake assay. The concentration of compound that inhibited cell viability by 50% (ic50 value) was calculated. All four oxysterols investigated induced the greatest cytotoxic effects following 96 h of exposure. 25‐Hydroxycholesterol exhibited the greatest cytotoxicity in both cell lines. Both β‐epox and α‐epox were more toxic to HepG2 cells than to Caco‐2 cells after the 48‐h exposure. Pretreatment of cells with either α‐ or γ‐TOC did not protect against oxysterol‐induced cytotoxicity. The caco‐2 cells treated with the high concentration (100 µm) of γ‐TOC were found to be more susceptible to oxysterol‐induced toxicity under the conditions employed in this study. Copyright © 2003 John Wiley & Sons, Ltd.
Comparative study of total protein, and total and lipid‐associated serum sialic acid levels in patients with type 2 diabetes mellitus
Authors: Ekin Suat , Meral Ismail , Gunduz Handan , Mert Nihat
Published: May 2003

The aim of the present study was to investigate the serum total protein (TP), total sialic acid (TSA), lipid‐associated sialic acid (LSA), LSA/TP, and LSA/TP values in type 2 diabetes mellitus (DM) patients. Two study groups (healthy controls and type 2 DM subjects) were examined. For the type 2 DM group, 120 patients (60 females and 60 males) who had been diagnosed and treated for type 2 DM in the Yuzuncu Yil University Hospital, Van, Turkey, were selected consecutively. Forty healthy individuals (20 females and 20 males) were selected from hospital staff and other outpatient clinics to serve as the control group. They were matched for age, sex, body mass index, and smoking status. None of the participants had taken vitamin or mineral supplements for at least 2 weeks before sampling. To determine serum glucose, TP, TSA, and LSA levels, blood samples were drawn after all of the subjects fasted overnight. It was found that diabetics had higher TSA, LSA, TSA/TP, and LSA/TP levels than controls. However, the TP levels were not significantly different between the groups. Our results showed that TSA, LSA, TSA/TP, and LSA/TP have interactive connections with DM. These parameters can be used as a diagnostic index for patients with DM. J. Clin. Lab. Anal. 17:124–126, 2003. © 2003 Wiley‐Liss, Inc.
Chronic phase lipids in sera of chronic fatigue syndrome (CFS), chronic ciguatera fish poisoning (CCFP), hepatitis B, and cancer with antigenic epitope resembling ciguatoxin, as assessed with MAb‐CTX
Authors: Hokama Y. , Uto G.A. , Palafox N.A. , Enlander D. , Jordan E. , Cocchetto A.
Published: May 2003

Clinical reports and descriptions of chronic fatigue syndrome (CFS) and chronic ciguatera fish poisoning (CCFP) show great similarities in clinical symptomology. These similarities in the literature suggested the exploration of lipids in sera of CFS, CCFP, and other diseases with the membrane immunobead assay (MIA), which is typically used for screening ciguateric ocean fish. Sera from patients with other diseases, including hepatitis B, cancer, and diabetes, were included to assess the degree of specificity involved. Sera were treated with acetone in a ratio of 1 part serum to 4 parts acetone. The suspension was centrifuged, and the acetone layer was evaporated. The residue was weighed and redissolved in 1.0 mL methanol and tested by the MIA, undiluted and titered to 1:160. The undiluted acetone fraction of the 37 normal showed ± activity to +activity with 16 no titer, 15 with 1:5 titer and two with 1:10 titer, and four with ≥1:40 titers. One hundred fifteen CFS sera showed 1 with 1+ and 114 with 2+ activity in the undiluted samples, 1 with 1:10 titer, 3 with 1:20 titer, 31 with 1:40 titer, 50 with 1:80 titer, and 30 with 160 titer. Thus 95.6% of the samples had ≥1:40 titer. Eight hepatitis B sera samples had ≥1:40 titers. Four CCFP samples had ≥1:40 titers. Three of 16 cancer samples had 1:40 titer. These data are summarized in Fig. 1. As shown in Table 1, a significant increase (P<0.001) in the chronic phase lipids (CPLs) was shown relative to the normal group. A preliminary chemical study in C18 octadecylsilyl columns showed all fractions (100% chloroform, 9:1 chloroform : methanol, 1:1 chloroform : methanol, and 100% methanol) to contain lipids reactive to MAb‐CTX with different intensities. Prostaglandins were shown in 100% methanol fraction. Competitive MIA with crude fish ciguatoxin and CFS with synthetic JKLM ciguatoxin epitope suggested similarities in structure with ciguatoxin. This was compatible with the neuroblastoma assay demonstrated in the C18 column fractions 9:1 and 1:1, chloroform : methanol solvents. J. Clin. Lab. Anal. 17:132–139, 2003. Copyright © 2003 John Wiley & Sons, Ltd.
Analysis of urinary N‐acetyl‐β‐D‐glucosaminidase using 2,4‐dinitrophenyl‐1‐thio N‐acetyl‐β‐D‐glucosaminide as the substrate
Authors: Yamada Magohei , Fujita Toshio
Published: May 2003

2,4‐Dinitrophenyl‐1‐thio N‐acetyl‐β‐D‐glucosaminide was examined as a new substrate for analyzing the level of N‐acetyl‐β‐D‐glucosaminidase in the urine of patients suffering from renal diseases. The analysis is based on the fact that the substrate, when hydrolyzed in the presence of N‐acetyl‐β‐D‐glucosaminidase, liberates 2,4‐dinitrothiophenol as the chromogen. The optimum pH for the enzyme reaction is 4.6, which is covered by the optimal range for the UV absorbance of the chromogen. The first‐order rate of increase of the absorbance at this pH was linear to the enzyme concentration up to 600 U/L, with a high sensitivity. Analytical reagents with glucosaminides of 2,4‐dinitrophenol and 2‐chloro‐4‐nitrophenol are less stable than the reagent with glucosaminide of 2,4‐dinitrothiophenol. The optimum pH for the absorbance of p‐nitrophenol and 2‐chloro‐4‐nitrophenol does not match that for the enzyme reaction. J. Clin. Lab. Anal. 17:127–131, 2003. © 2003 Wiley‐Liss, Inc.
Cell‐free DNA is released from tumor cells upon cell death: A study of tissue cultures of tumor cell lines
Authors: Li Chia‐Ni , Hsu Hui‐Lun , Wu Tsu‐Lan , Tsao Kuo‐Chien , Sun Chien‐Feng , Wu James T.
Published: May 2003

To determine the source of cell‐free DNA detected in the serum of cancer patients, we monitored the release of cell‐free DNA and tumor markers from tumor cell lines using the cell culture technique. During the first 6 days of cell culture, we found very low concentrations of DNA and a steady increase of the CA 125 released from the SK‐BR3 tumor cell lines during cell growth. A sudden increase of cell‐free DNA detected in the cell medium coincided with cell death. As the cells died, the concentration of cell‐free DNA declined but the concentration of CA 125 increased. The sudden release of cell‐free DNA observed upon cell death was also found on the cell cultures of additional tumor cell lines, including A549, RD, and SK‐N‐SH cells. It appears that the majority of cell‐free DNA detected in the serum of cancer patients comes from tumor cells following cell death and cell necrosis. The concentration of cell‐free DNA released is related to the number of dead cells, whereas that of the tumor marker CA 125 is associated with the presence of the total number of cells (dead or alive). J. Clin. Lab. Anal. 17:103–107, 2003. © 2003 Wiley‐Liss, Inc.
Multiplex PCR: Rapid DNA cycling in a conventional thermal cycler
Authors: Markoulatos P. , Siafakas N. , Katsorchis T. , Moncany M.
Published: May 2003

Multiplex polymerase chain reaction (PCR) is a variant of PCR in which two or more target sequences are simultaneously amplified in the same reaction. In the present study we investigated the limits to which the duration of multiplex PCR steps can be shortened using the thermal cycler Gene Amp PCR system 9600 (Perkin Elmer, Oak Brook, IL). The present multiplex PCR assay simultaneously detects five different herpes viruses (HSV‐1, HSV‐2, VZV, CMV, and EBV) and assesses sample suitability in a single amplification round of 40 cycles. It appears that when six target sequences are simultaneously amplified in multiplex PCR, extension time is a critical parameter. Using a PCR protocol of 0 sec at 95°C, 0 sec at 60°C, and 0 sec at 74°C with Platinum Taq DNA polymerase (Life Technologies, Gaithersburg, MD), we were able to reduce the total cycling time of the multiplex PCR assay to as little as 55 min, without affecting the yield of PCR products or the specificity of the assay. It may be necessary to optimize each specific apparatus and template, but any such optimization would be trivial. J. Clin. Lab. Anal. 17:108–112, 2003. © 2003 Wiley‐Liss, Inc.
Evaluation of the Sysmex Xe‐2100® hematology analyzer in hospital use
Authors: Nakul‐Aquaronne Danièle , Sudaka‐Sammarcelli Isabelle , Ferrero‐Vacher Corinne , Starck Benoit , Bayle Jacques
Published: May 2003

The Sysmex XE‐2100® (Sysmex Corp. Kobe, Japan) is a latest‐generation hematology analyzer. Its optical and electrical measuring technology is improved by the addition of flux cytometry, fluorescence, and differential lysis. Its analytical performance in terms of precision, reproducibility, linearity, carryover, and time stability was found to be entirely satisfactory. In addition, the results of 500 complete blood counts and differentials correlated perfectly with those obtained by the Coulter STKS® (Beckman Coulter, Villapointe, France). The comparison of 500 leukocyte differential count results analyzed in parallel with optical microscopy and the XE‐2100® were surprising, and favorable to the XE‐2100®. This analyzer provides the user with an undeniable feeling of security concerning its reliability in detecting and identifying anomalies in the automated leukocyte differential count. With a sensitivity of 96%, a negative predictive value (NPV) of 98%, and a false‐negative (FN) rate of 4%, the XE‐2100® has perhaps reached the technological limits for a machine performing morphological recognition of normal and pathological blood cells. J. Clin. Lab. Anal. 17:113–123, 2003. © 2003 Wiley‐Liss, Inc.
Influence of response factors on determining equilibrium association constants of non‐covalent complexes by electrospray ionization mass spectrometry
Authors: Gabelica Valérie , Galic Nives , Rosu Frédéric , Houssier Claude , De Pauw Edwin
Published: June 2003

A method for determining the equilibrium association constant of a complexation reaction A + B ⇋ AB by electrospray ionization mass spectrometry is described. The method consists in measuring the relative intensities of the peaks corresponding to A and to AB in equimolar A–B solutions at different concentrations C0. The results are fitted by a non‐linear least‐squares procedure, with the two variable parameters being the equilibrium association constant Ka and a factor R, defined by I(AB)/I(A) = R × [AB]/[A]. The factor R is the ratio between the response factors of AB and A, and corrects for the relative electrospray responses of the complex and the free substrate A, mass discrimination of instrumental origin and/or moderate in‐source dissociation. The method is illustrated with the following two systems: complexes between a double‐stranded 12‐base pair oligonucleotide and minor groove binders, and cyclodextrin complexes with α,ω‐dicarboxylic acids. For the oligonucleotide complexes, it is found that the response of the complex is not dramatically different to the response of the free oligonucleotide duplex, as the double helix conformation is disturbed by the drug only to a minor extent. In the case of cyclodextrin complexes, these complexes were found to have a much higher response than free cyclodextrin. This may be due to the fact that cyclodextrin is neutral in solution, whereas the complex is charged, but it can also stem from the fact that a significant proportion of the complex is in a non‐inclusion geometry. The present method requires the exact determination of the concentrations of the reactants and is applicable to 1 : 1 complexes. Copyright © 2003 John Wiley & Sons, Ltd.
Monitoring of unfolding of metallo‐proteins by electrospray ionization mass spectrometry
Authors: Cunsolo Vincenzo , Foti Salvatore , La Rosa Carmelo , Saletti Rosaria , Canters G. W. , Verbeet M. Ph.
Published: June 2003

An electrospray ionisation (ESI) mass spectrometric method for the determination of the equilibrium constant and free energy (ΔG) of protein unfolding was used to monitor the denaturation process at different pH of three metallo‐proteins, i.e. wild‐type copper azurin, zinc azurin and wild‐type amicyanin. The time course of the unfolding process was followed by dissolving the proteins under denaturing conditions (methanol–water (1 : 1, v/v)) at different pH (2.5, 3.0, 3.5) and recording ESI spectra at time intervals. The spectra showed two series of peaks, corresponding to the native holo‐protein and the unfolded apo‐protein. From the intensity ratio of these two series of peaks at increasing time and at equilibrium, the equilibrium constants for the unfolding process for the three proteins could be determined. From these equilibrium constants a ΔG° derivation was attempted. The ΔG° values obtained decrease with decrease in pH, in agreement with the expected reduction of conformational stability of proteins at lower pH. The results obtained confirm that ESI‐MS can be used for monitoring of unfolding process and to derive quantitative thermodynamic data. Copyright © 2003 John Wiley & Sons, Ltd.
Low‐temperature SIMS mass spectra of diethyl ether
Authors: Kosevich Marina V. , Shelkovsky Vadim S. , Boryak Oleg A. , Gömöry Agnes , Végh Peter D. , Vékey Károly
Published: June 2003

For the first time a secondary ion mass spectrum of diethyl ether was obtained at low temperature. The spectrum recording became possible by carefully selecting the range of experimental conditions for the production of a cluster‐type spectrum. This range is specified by the threshold for spectrum appearance above the melting temperature of the frozen sample and a fairly short time span of existence of the liquid estimated as only a few minutes. The latter necessitates rather rapid spectrum detection. In practice, about 1 min was available for recording of the cluster‐type spectra. The secondary emission mass spectrum of diethyl ether appeared to be rich in peaks: along with abundant protonated clusters Mn·H+ (n = 1–12), unusually intense [Mn − H]+ and weaker Mn+· peaks were present accompanied by several sets of fragmented clusters, [Mn − 15]+, [Mn − 29]+, [Mn − 27]+, [Mn − 45]+, and monohydrates, Mn·H2O·H+. The analysis of all the peaks showed that the pattern of fragment clusters is qualitatively similar to the pattern of fragmentation of the diethyl ether molecular ion under high‐energy electron impact. The general features of the behaviour of diethyl ether under low‐temperature mass spectrometric conditions were similar to those observed earlier for some other organic solvents. Copyright © 2003 John Wiley & Sons, Ltd.
Volatile polydimethylcyclosiloxanes in the ambient laboratory air identified as source of extreme background signals in nanoelectrospray mass spectrometry
Authors: Schlosser Andreas , Volkmer‐Engert Rudolf
Published: June 2003

Polydimethylcyclosiloxanes, an almost ubiquitous air contaminant, can interfere with nanoelectrospray analysis. The sensitivity of nanoelectrospray to these volatile air contaminants was demonstrated in this study. The intensity of the interfering ion signals caused by these compounds can be decreased by changing the position of the nanoESI needle and almost completely suppressed by applying a flow of pure nitrogen around the needle and the sample cone. The nitrogen flow causes a slight shift in charge distribution, but does not influence the sensitivity for peptide detection. Copyright © 2003 John Wiley & Sons, Ltd.
Decomposition of protein nitrosothiolsin matrix‐assisted laser desorption/ionization and electrospray ionization mass spectrometry
Authors: Kaneko Rina , Wada Yoshinao
Published: June 2003

The S‐nitrosylation of proteins is involved in the trafficking of nitric oxide (NO) in intra‐ and extracellular milieus. To establish a mass spectrometric method for identifying this post‐translational modification of proteins, a synthetic peptide and transthyretin were S‐nitrosylated in vitro and analyzed by electrospray ionization (ESI) and matrix‐assisted laser desorption/ionization (MALDI) mass spectrometry. The intact molecular ion species of nitrosylated compounds was identified in the ESI mass spectrum without elimination of the NO group. However, the labile nature of the S—NO bond was evident when the in‐source fragmentation efficiently generated [M + H − 30]+ ions. The decomposition was prominent for multiply charged transthyretin ions with high charge states under ordinary ESI conditions, indicating that the application of minimum nozzle potentials was essential for delineating the stoichiometry of nitrosylation in proteins. With MALDI, the S—NO bond cleavage occurred during the ionization process, and the subsequent reduction generated [M + H − 29]+ ions. Copyright © 2003 John Wiley & Sons, Ltd.
Mass spectrometric characterization of mitochondrial electron transport complexes: subunits of the rat heart ubiquinol–cytochrome c reductase
Authors: Sun Gang , Kinter Michael T. , Anderson Vernon E.
Published: June 2003

Complex III of the mitochondrial electron transport chain, ubiquinol–cytochrome c reductase, was isolated by blue native polyacrylamide gel electrophoresis. Ten of the 11 polypeptides present in this complex were detected directly by matrix‐assisted laser desorption/ionization time‐of‐flight mass spectrometry (MALDI‐TOFMS) following electroelution of the active complex. Tryptic and chymotryptic digestion of the complex permit the identification of specific peptides from all of the protein subunits with 70% coverage of the 250 kDa complex. The mass of all 11 proteins was confirmed by second dimension Tricine sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS‐PAGE) and elution of the separated polypeptides. Additionally, the identity of the core I, core II, cytochrome c and the Rieske iron–sulfur protein were confirmed by liquid chromatography/tandem mass spectrometry (LC/MS/MS) characterization of the peptides generated by in‐gel trypsin digestion of the SDS‐PAGE separated proteins. The methodology demonstrated for analyzing this membrane‐bound electron transport complex should be applicable to other membrane complexes, particularly the other mitochondrial electron transport complexes. The MS analysis of the peptides obtained by in‐gel digestion of the intact complex permits the simultaneous characterization of the native proteins and modifications that contribute to mitochondrial deficits that have been implicated as contributing to pathological conditions. Copyright © 2003 John Wiley & Sons, Ltd.
Fragmentation of dipyridamole and related dipyrimidines by electrospray ionization collisional activated decomposition mass spectrometry
Authors: Rodrigues Filho Edson , Almeida Adaila Marta Paixão , Tabak Marcel
Published: June 2003

The coronary vasodilator, co‐activator of antitumor compounds and antioxidant drug dipyridamole and several of its derivatives were studied by electrospray ionization (ESI) combined with collisional activated decomposition (CAD) in both positive and negative modes. These compounds produce abundant monocharged ions ([M + H]+) under ESI. Interpretation of the CAD spectra showed that fragmentation occurs preferentially in the ethanolamine groups attached at C‐2, C‐4, C‐6 and C‐8. 2‐Methoxyethanol is eliminated when ethanolamines are in positions C‐2/C‐6 and 2‐aziridinethanol is eliminated from C‐4/C‐8 ethanolamines. The proposed fragmentation schemes were supported by deuterium labeling experiments and tandem mass spectrometry. Copyright © 2003 John Wiley & Sons, Ltd.
Quantitative analysis of ES‐285, an investigational marine anticancer drug, in human, mouse, rat, and dog plasma using coupled liquid chromatography and tandem mass spectrometry
Authors: Stokvis E. , Nan‐Offeringa L. , Rosing H. , López‐Lázaro L. , Aceña J. L. , Miranda E. , Lyubimov A. , Levine B. S. , D'Aleo C. , Schellens J. H. M. , Beijnen J. H.
Published: June 2003

A method was developed for the quantitative analysis of the novel anticancer agent ES‐285 (spisulosine; free base) in human, mouse, rat, and dog plasma using high‐performance liquid chromatography/electrospray ionization tandem mass spectrometry in order to support pre‐clinical and clinical studies with the drug. Sample preparation was carried out by protein precipitation with acetonitrile, containing isotopically labeled (d3) ES‐285 as internal standard. Aliquots of 10 µl of the supernatant were injected directly on to an Inertsil ODS‐3 column (50 × 2.0 mm i.d., 5 µm). Elution was carried out using methanol–10 mM ammonium formate (pH 4) in water (80 : 20, v/v) pumped at a flow‐rate of 0.2 ml min−1 with a run time of 8 min. Multiple reaction monitoring chromatograms obtained on an API365 triple‐quadrupole mass spectrometer were used for quantification. The lower limit of quantitation (LLOQ) was 10 ng ml−1 in human, mouse, rat, and dog plasma and the linear dynamic range extended to 500 ng ml−1. A full validation of the method was performed in human plasma, and partial validations were performed in mouse, rat and dog plasma. Accuracies and precisions were <20% at the LLOQ concentration and <15% for all other concentrations in all matrices. ES‐285 was stable during all steps of the assay. Thus far this method has been used successfully to analyze over 500 samples in pre‐clinical trials, and will be implemented in the planned clinical phase I studies. Copyright © 2003 John Wiley & Sons, Ltd.
Structural characterization and isomer differentiation of chalcones by electrospray ionization tandem mass spectrometry
Authors: Zhang Junmei , Brodbelt Jennifer S.
Published: June 2003

A series of chalcones were characterized by electrospray ionization tandem mass spectrometry (MSn). Several ionization modes were evaluated, including protonation, deprotonation and metal complexation, with metal complexation being the most efficient. Collision‐activated dissociation (CAD) was used to characterize the structures, and losses commonly observed include H2, H2O, CO and CO2, in addition to methyl radicals for the methoxy‐containing chalcones. CAD of the metal complexes, especially [CoII (chalcone—H) 2,2′‐bipyridine]+, allowed the most effective differentiation of the isomeric chalcones with several diagnostic fragment ions appearing upon activation of the metal complexes. MSn experiments were performed to support identification of some fragment ions and to verify the proposed fragmentation pathways. In several cases, MSn indicated that specific neutral losses occurred by stepwise pathways, such as the neutral loss of 44 u as CH3· and HCO·, or CH4 and CO, in addition to CO2. Copyright © 2003 John Wiley & Sons, Ltd.