bluuebunny/crossref_metadata_2025 huggingface dataset:
Modeling the mass transfer in solvent‐extraction processes with hollow‐fiber membranes
Authors: Bocquet S. , Torres A. , Sanchez J. , Rios G. M. , Romero J.
Published: February 2005

This work focuses on the modeling of solvent‐extraction processes carried out in a hollow‐fiber membrane contactor (HFC). A resistance‐in‐series model has been adapted to deal with a conventional solvent or a nonconventional solvent in subcritical conditions. Two kinds of applications have been chosen to test its validity: extraction of ethanol or acetone from an aqueous solution by subcritical carbon dioxide or propane in a single‐fiber module, and extraction of sulfur aroma compounds by hexane. Modifications in membrane characteristics and operating parameters have been investigated to determine optimal conditions. Simulations carried out with carbon dioxide have shown that the resistance in the solvent boundary layer is always negligible, whereas, in the case of hexane, the resistance in the aqueous boundary layer is always predominant. For the application with subcritical carbon dioxide, optimal values of feed and solvent velocities have been obtained. These thresholds correspond to the point where the resistance in the membrane becomes predominant. © 2005 American Institute of Chemical Engineers AIChE J, 2005
Novel polyelectrolyte carboxymethyl konjac glucomannan–chitosan nanoparticles for drug delivery. I. Physicochemical characterization of the carboxymethyl konjac glucomannan–chitosan nanoparticles
Authors: Du Jian , Sun Rui , Zhang Sheng , Zhang Li‐Fang , Xiong Cheng‐Dong , Peng Yu‐Xing
Published: February 2005

Carboxymethyl konjac glucomannan–chitosan (CKGM–CS) nanoparticles, which are well dispersed and stable in aqueous solution, were spontaneously prepared under very mild conditions via polyelectrolyte complexation. The physicochemical properties of the nanoparticles were identified by Zetasizer 3000 and Fourier transform infrared. It was found that at various CKGM and CS concentrations the particles ranged in size from approximately 50 to 1200 nm, and the zeta potential from 15 to 45 mV. By changing pH value of the medium and increasing the concentration of salt, the mean size of the particles increased and the zeta potential decreased. Also, investigations on the encapsulation efficiency of the bovine serum albumin loaded CKGM–CS nanoparticles were also undertaken. This nanoparticulate system driven by complex formation shows potential as an advanced drug delivery system for water‐soluble drugs. © 2005 Wiley Periodicals, Inc. Biopolymers, 2005
Monovalent cations affect the free solution mobility of DNA by perturbing the hydrogen‐bonded structure of water
Authors: Stellwagen Earle , Dong Qian , Stellwagen Nancy C.
Published: February 2005

The free solution mobilities of single‐ and double‐stranded DNA molecules of various molecular weights have been measured by capillary electrophoresis in solutions of constant ionic strength containing a common anion and fifteen different monovalent cations. In solutions with the same ionic composition, the mobilities of different DNA molecules can vary by up to 20%, depending on molecular weight, the number of strands, and the presence or absence of A‐tracts, runs of four or more contiguous adenine residues. Importantly, the mobilities observed for the same DNA sample can vary by up to 40% in solutions containing different cations. The mobility differences observed for the same DNA in solutions containing different cations cannot be rationalized by differences in the anhydrous radii or intrinsic conductivities of the various cations, or by the sequence‐dependent binding of certain cations to A‐tracts. Instead, the observed mobilities are linearly correlated with the average number of water–water hydrogen bonds that are present in solutions containing different cations. The mobilities are also correlated with the viscosity B coefficients of the various cations and with the rotational correlation times frictional coefficients observed for water molecules in solutions containing different cations. Hence, monovalent cations modify the free solution mobility of DNA primarily by perturbing the hydrogen‐bonded structure of water, affecting the friction experienced by the migrating DNA molecules during electrophoresis. © 2005 Wiley Periodicals, Inc. Biopolymers 78: 62–68, 2005
New anticoagulants and thromboprophylaxis
Authors: Hoppener Marnix R , Büller Harry R
Published: February 2005

May soon replace heparin and warfarin
Randomized clinical trial of the effects of oral preoperative carbohydrates on postoperative nausea and vomiting after laparoscopic cholecystectomy
Authors: Hausel J , Nygren J , Thorell A , Lagerkranser M , Ljungqvist O
Published: February 2005

Background

A carbohydrate-rich drink (CHO) has been shown to reduce preoperative discomfort. It was hypothesized that it may also reduce postoperative nausea and vomiting (PONV).

Methods

Patients undergoing elective laparoscopic cholecystectomy under inhalational anaesthesia (127 women and 45 men; mean(s.d.) 48(15) years) were randomized to either preoperative fasting, intake of CHO (50 kcal/100 ml, 290 mOsm/kg) or placebo. The non-fasting groups were double-blinded; patients ingested 800 ml of liquid on the evening before surgery and 400 ml 2 h before anaesthesia. Nausea and pain scores on a visual analogue scale (VAS) and episodes of PONV were recorded up to 24 h after surgery.

Results

The incidence of PONV was lower in the CHO than in the fasted group between 12 and 24 h after surgery (P = 0·039). Nausea scores in the fasted and placebo groups were higher after operation than before admission to hospital (P = 0·018 and P < 0·001 respectively), whereas there was no significant change in the CHO group. No intergroup differences in VAS scores were seen. The use of anaesthetics, opioids, antiemetics and intravenous fluids was similar in all groups.

Conclusion

CHO may have a beneficial effect on PONV 12–24 h after laparoscopic cholecystectomy.
Maternally and paternally silenced imprinted genes differ in their intron content
Authors: Fahey Marie E , Mills Walter , Higgins Desmond G , Moore Tom
Published: February 2005

Imprinted genes exhibit silencing of one of the parental alleles during embryonic development. In a previous study imprinted genes were found to have reduced intron content relative to a non‐imprinted control set (Hurst et al., ). However, due to the small sample size, it was not possible to analyse the source of this effect. Here, we re‐investigate this observation using larger datasets of imprinted and control (non‐imprinted) genes that allow us to consider mouse and human, and maternally and paternally silenced, imprinted genes separately. We find that, in the human and mouse, there is reduced intron content in the maternally silenced imprinted genes relative to a non‐imprinted control set. Among imprinted genes, a strong bias is also observed in the distribution of intronless genes, which are found exclusively in the maternally silenced dataset. The paternally silenced dataset in the human is not different to the control set; however, the mouse paternally silenced dataset has more introns than the control group. A direct comparison of mouse maternally and paternally silenced imprinted gene datasets shows that they differ significantly with respect to a variety of intron‐related parameters. We discuss a variety of possible explanations for our observations. Copyright © 2005 John Wiley & Sons, Ltd.
Exploring the foundation of genomics: a Northern blot reference set for the comparative analysis of transcript profiling technologies
Authors: Kemmer Danielle , Faxén Margareta , Hodges Emily , Lim Jonathan , Herzog Elena , Ljungström Elsebrit , Lundmark Anders , Olsen Mary K. , Podowski Raf , Sonnhammer Erik L. L. , Nilsson Peter , Reimers Mark , Lenhard Boris , Roberds Steven L. , Wahlestedt Claes , Höög Christer , Agarwal Pankaj , Wasserman Wyeth W.
Published: February 2005

In this paper we aim to create a reference data collection of Northern blot results and demonstrate how such a collection can enable a quantitative comparison of modern expression profiling techniques, a central component of functional genomics studies. Historically, Northern blots were the de facto standard for determining RNA transcript levels. However, driven by the demand for analysis of large sets of genes in parallel, high‐throughput methods, such as microarrays, dominate modern profiling efforts. To facilitate assessment of these methods, in comparison to Northern blots, we created a database of published Northern results obtained with a standardized commercial multiple tissue blot (dbMTN). In order to demonstrate the utility of the dbMTN collection for technology comparison, we also generated expression profiles for genes across a set of human tissues, using multiple profiling techniques. No method produced profiles that were strongly correlated with the Northern blot data. The highest correlations to the Northern blot data were determined with microarrays for the subset of genes observed to be specifically expressed in a single tissue in the Northern analyses. The database and expression profiling data are available via the project website (http://www.cisreg.ca). We believe that emphasis on multi‐technique validation of expression profiles is justified, as the correlation results between platforms are not encouraging on the whole. Supplementary material for this article can be found at: http://www.interscience.wiley.com/jpages/1531‐6912/suppmat Copyright © 2005 John Wiley & Sons, Ltd.
SOM‐based class discovery exploring the ICA‐reduced features of microarray expression profiles
Authors: Dragomir Andrei , Mavroudi Seferina , Bezerianos Anastasios
Published: February 2005

Gene expression datasets are large and complex, having many variables and unknown internal structure. We apply independent component analysis (ICA) to derive a less redundant representation of the expression data. The decomposition produces components with minimal statistical dependence and reveals biologically relevant information. Consequently, to the transformed data, we apply cluster analysis (an important and popular analysis tool for obtaining an initial understanding of the data, usually employed for class discovery). The proposed self‐organizing map (SOM)‐based clustering algorithm automatically determines the number of ‘natural’ subgroups of the data, being aided at this task by the available prior knowledge of the functional categories of genes. An entropy criterion allows each gene to be assigned to multiple classes, which is closer to the biological representation. These features, however, are not achieved at the cost of the simplicity of the algorithm, since the map grows on a simple grid structure and the learning algorithm remains equal to Kohonen's one. Copyright © 2005 John Wiley & Sons, Ltd.
Xenophilic Complexes Bearing a TpR Ligand, [TpRMM′Ln] [TpR=Tp, Tp# (Tp); M=Ni, Co, Fe, Mn; M′Ln=Co(CO)4, Co(CO)3(PPh3), RuCp(CO)2]: The Two Metal Centers are Held Together not by Covalent Interaction but by Electrostatic Attraction
Authors: Uehara Kazuhiro , Hikichi Shiro , Inagaki Akiko , Akita Munetaka
Published: February 2005

A series of dinuclear complexes, [TpRMM′Ln] [TpMCo(CO)4 (1; M=Ni, Co, Fe, Mn); Tp#MCo(CO)4 (1′; M=Ni, Co); Tp#NiRuCp(CO)2 (3′)] (Tp=hydrotris(3,5‐diisopropylpyrazolyl)borato; Tp# (Tp)=hydrotris(3,5‐dimethyl‐4‐bromopyrazolyl)borato), has been prepared by treatment of the cationic complexes [TpM(NCMe)3]PF6 or the halo complexes [Tp#MX] with the appropriate metalates. Spectroscopic and crystallographic characterization of 1–3′ reveals that the tetrahedral, high‐spin TpRM fragment and the coordinatively saturated carbonyl–metal fragment (M′Ln) are connected only by a metal–metal interaction and, thus, the dinuclear complexes belong to a unique class of xenophilic complexes. The metal–metal interaction in the xenophilic complexes is polarized, as revealed by their νCO vibrations and structural features, which fall between those of reference complexes: covalently bonded species [RM′Ln] and ionic species [M′Ln]−. Unrestricted DFT calculations for the model complexes [TpNiCo(CO)4], [TpNiCo(CO)3(PH3)], and [TpNiRuCp(CO)2] prove that the two metal centers are held together not by covalent interactions, but by electrostatic attractions. In other words, the obtained xenophilic complexes can be regarded as carbonylmetalates, in which the cationic counterpart interacts with the metal center rather than the oxygen atom of the carbonyl ligand. The xenophilic complexes show divergent reactivity dependent on the properties of donor molecules. Hard (N and O donors) and soft donors (P and C donors) attack the TpRM part and the MLn moiety, respectively. The selectivity has been interpreted in terms of the hard–soft theory, and the reactions of the high‐spin species 1–3′ with singlet donor molecules should involve a spin‐crossover process.
Double‐Helical Ultrastructure of Polycationic Dendronized Polymers Determined by Single‐Particle Cryo‐TEM
Authors: Böttcher Christoph , Schade Boris , Ecker Christof , Rabe Jürgen P. , Shu Lijin , Schlüter A. Dieter
Published: February 2005

The ultrastructure of cationic dendronized polymers (denpols) of third and fourth generations (PG3 and PG4) in water was determined by using single‐particle cryo‐transmission electron microscopy (cryo‐TEM). At concentrations in the region of 50 mg L−1, networks of double‐stranded fibers were revealed that exhibit well‐defined diameters of 5.9 nm±0.4 nm for PG3 and 7.4 nm±0.4 nm for PG4. The structure varies with progression along the fibers, and includes a double helix with a pitch of 7.0±0.4 nm for PG3 and 9.0±0.4 nm for PG4. The formation of the double strands is attributed to the hydrophobic effect and limited crowding in the dendron shell of the third and fourth generation denpols investigated. From solutions of lower concentrations (around 10 mg L−1), isolated molecular fibers were adsorbed onto high‐energy surfaces and examined by performing scanning force microscopy (SFM) on mica, and after staining, TEM on glow‐discharged carbon films. In both cases, characteristic undulations of single strands were observed, which are attributed largely to the adsorption process.
Preparation of murine B7.1‐glycosylphosphatidylinositol and transmembrane‐anchored staphylococcal enterotoxin
Authors: Yi Pingyong , Yu Hai , Ma Wenxue , Wang Qingqing , Minev Boris R.
Published: February 2005

BACKGROUND

The authors have previously reported a tumor cell vaccine modified with superantigen staphylococcal enterotoxin A (SEA) and its antitumor effect. The tumor cell vaccines modified with multiple immune activators frequently elicited stronger immune responses against established tumors than single‐modified vaccines.

METHODS

The authors explored the effectiveness of a tumor cell vaccine transduced with immune activators, dual‐modified using the protein transfer technique. First, a glycosylphosphatidylinositol (GPI)‐anchored murine B7.1 (mB7.1‐GPI) and a transmembrane‐anchored SEA (TM‐SEA) were genetically generated. Then, the murine lymphoma EL4 cells were dual modified with the incorporation of mB7.1‐GPI and TM‐SEA onto the cell surface. Flow cytometry and laser confocal microscopy showed that the incorporation of B7.1 and SEA molecules onto EL4 cells was quite stable.

RESULTS

The dual‐modified tumor cell vaccine EL4/mB7.1‐GPI + TM‐SEA elicited significantly stronger antitumor immune responses both in vitro and in vivo when compared with the single‐modified tumor cell vaccines EL4/mB7.1‐GPI and EL4/TM‐SEA.

CONCLUSIONS

The results of the current study validated the novel approach for preparing tumor cell vaccines modified with dual immune active molecules using the protein transfer technique, and supported the feasibility and effectiveness of the dual‐modified tumor cell vaccine. Cancer 2005. © 2005 American Cancer Society.
Disturbed root development of permanent teeth after pediatric stem cell transplantation
Authors: Hölttä Päivi , Hovi Liisa , Saarinen‐Pihkala Ulla M. , Peltola Jaakko , Alaluusua Satu
Published: February 2005

BACKGROUND

Deficient dental root development has been reported after conventional pediatric anticancer therapy, but less information is available on stem cell transplantation (SCT) recipients.

METHODS

Root‐crown (R/C) ratios of fully developed permanent teeth were assessed from panoramic radiographs of 52 SCT recipients, who were treated when they were age < 10 years. Using standard deviation scores (SDSs), the authors compared the R/C ratios to the corresponding tooth and gender‐specific values in a healthy population. The percentage of affected R/C ratios per individual was examined in a subgroup of 39 (SG39) patients with advanced tooth development. The effects of total body irradiation (TBI) and SCT age on the R/C ratios were studied in TBI and high‐dose chemotherapy (HDC = non‐TBI) groups and in 3 age groups (≤ 3.0 years, 3.1–5.0 years, ≥ 5.1 years).

RESULTS

Per individual, 77% of the fully developed permanent teeth were affected in SG39. At the tooth level, in 77% of the 945 teeth studied (52 patients), the R/C ratios were outside ±2 SDSs. More teeth were affected in the TBI (85%) than in the non‐TBI (55%) group (P < 0.001). The teeth of the patients who were ages 3.1–5.0 years old at SCT presented with the most severe aberrations of the R/C ratio (mean SDS = −4.4) whereas the teeth of the youngest (age ≤ 3.0 years) and the oldest (age ≥ 5.1 years) patients were equally affected (mean SDSs = −3.1 and −3.0, respectively).

CONCLUSIONS

Disturbances of dental root growth always followed pediatric SCT. HDC alone intensely harmed root growth but TBI further increased the adverse effects that were most extensive in the patients 3.1–5.0 years at SCT. These sequelae should be taken into account during the lifelong dental follow‐up to minimize the clinical consequences of dental injuries. Cancer 2005. © 2005 American Cancer Society.
Support and optimization of Java RMI over a Bluetooth environment
Authors: Wei Pu‐Chen , Chen Chung‐Hsin , Chen Cheng‐Wei , Lee Jenq‐Kuen
Published: February 2005

Distributed object‐oriented platforms are increasingly important over wireless environments for providing frameworks for collaborative computations and for managing a large pool of distributed resources. Due to limited bandwidths and heterogeneous architectures of wireless devices, studies are needed into supporting object‐oriented frameworks over heterogeneous wireless environments and optimizing system performance. In our research work, we are working towards efficiently supporting object‐oriented environments over heterogeneous wireless environments. In this paper, we report the issues and our research results related to the efficient support of Java RMI over a Bluetooth environment. In our work, we first implement support for Java RMI over Bluetooth protocol stacks, by incorporating a set of protocol stack layers for Bluetooth developed by us (which we call JavaBT) and by supporting the L2CAP layer with sockets that support the RMI socket. In addition, we model the cost for the access patterns of Java RMI communications. This cost model is used to guide the formation and optimizations of the scatternets of a Java RMI Bluetooth environment. In our approach, we employ the well‐known BTCP algorithm to observe initial configurations for the number of piconets. Using the communication‐access cost as a criterion, we then employ a spectral‐bisection method to cluster the nodes in a piconet and then use a bipartite matching scheme to form the scatternet. Experimental results with the prototypes of Java RMI support over a Bluetooth environment show that our scatternet‐formation algorithm incorporating an access‐cost model can further optimize the performances of such as system. Copyright © 2005 John Wiley & Sons, Ltd.
CSFS: a Java enabled network file storage system
Authors: Hua Han , Yafei Dai , Xiaoming Li
Published: February 2005

The CSFS (cryptographic storage file system) is a network file storage system that is suitable for a small‐to‐medium sized networks such as a campus network. In a CSFS, a lot of distributed file servers are organized in a star‐liked architecture. File names are stored in a name server and file data are stored in distributed file servers. A CSFS has good scalability and is able to accommodate hundreds of file servers. We implemented a CSFS in pure Java and tested the system with a benchmark. The test results show that CSFS delivers acceptable performance for general file operations. Its performance of file upload and download is as efficient as FTP. It can support more than 450 concurrent online users. Copyright © 2005 John Wiley & Sons, Ltd.
Generic programming for high‐performance scientific applications
Authors: Lee Lie‐Quan , Lumsdaine Andrew
Published: February 2005

We present case studies that apply generic programming to the development of high‐performance parallel code for solving two archetypal partial differential equations (PDEs). We examine the overall structure of the example scientific codes and consider their generic implementation. With a generic approach it is a straightforward matter to reuse software components from different sources; implementations with components from the Iterative Template Library (ITL), the Matrix Template Library (MTL), Blitz++, A++/P++, and Fortran BLAS are presented. Our newly developed Generic Message Passing library is used for communication. We compare the generic implementations with equivalent implementations developed with alternative libraries and languages and discuss performance as well as software engineering issues. Copyright © 2005 John Wiley & Sons, Ltd.
7‐Ketocholesterol favors lipid accumulation and colocalizes with Nile Red positive cytoplasmic structures formed during 7‐ketocholesterol–induced apoptosis: Analysis by flow cytometry, FRET biphoton spectral imaging microscopy, and subcellular fractionation
Authors: Vejux Anne , Kahn Edmond , Dumas Dominique , Bessède Ginette , Ménétrier Franck , Athias Anne , Riedinger Jean‐Marc , Frouin Frédérique , Stoltz Jean‐François , Ogier‐Denis Eric , Todd‐Pokropek Andrew , Lizard Gérard
Published: February 2005

Background

Oxidized low‐density lipoproteins play key roles in atherosclerosis. Their toxicity is at least in part due to 7‐ketocholesterol (7KC), which is a potent inducer of apoptosis. In this study on human promonocytic U937 cells, we determined the effects and the interactions of 7KC with cellular lipids during 7KC‐induced apoptosis.

Methods

Morphologic and functional changes were investigated by microscopic and flow cytometric methods after staining with propidium iodide, 3,3′‐dihexyloxacarbocyanine iodide, and Hoechst 33342. Cellular lipid content was identified by using filipin to quantify free cholesterol and Nile Red (NR), which emit a yellow or orange‐red fluorescence in the presence of neutral and polar lipids, respectively. After staining with NR, interactions of 7KC with cellular lipids were identified by fluorescence resonance energy transfer biphoton spectral imaging confocal microscopy and by subcellular fractionation, gas chromatography, and mass spectrometry.

Results

During 7KC‐induced apoptosis the fluorescence from filipin and the ratio of measured (orange‐red vs. yellow) fluorescence of NR were enhanced. Spectral analysis of images obtained in biphoton mode and resulting factor images demonstrated the occurrence of fluorescence resonance energy transfer between 7KC and NR and the subsequent colocalization of 7KC and NR. These data were in agreement with biochemical characterization and demonstrated that 7KC and neutral and polar lipids accumulate in NR‐stained cytoplasmic structures.

Conclusions

During 7KC‐induced apoptosis, 7KC modifies the cellular content of neutral and polar lipids, favors free cholesterol accumulation, and colocalizes with neutral and polar lipids that are inside NR‐stained cytoplasmic structures. © 2005 Wiley‐Liss, Inc.
Developmental expression of metalloproteases ADAM 9, 10, and 17 becomes restricted to divergent pancreatic compartments
Authors: Asayesh Amir , Alanentalo Tomas , Khoo Nelson K.S. , Ahlgren Ulf
Published: February 2005

The A Disintegrin And Metalloprotease (ADAM) family of metalloproteases affects a variety of proteins with important roles in development and disease, including growth factors and adhesion molecules. We have analyzed the expression patterns of ADAMs 9, 10, and 17 during pancreas ontogeny. All ADAMs investigated were expressed in the pancreatic anlagen but invariably became restricted to divergent pancreatic compartments. ADAM9 and 17 became restricted to the insulin‐producing β‐cells and all islet cells, respectively. During embryogenesis, ADAM10 was detected predominantly in acinar cells, but in the adult, it was localized to the cell surface membrane of both endocrine and exocrine cells. In addition to ADAM9, a potential prognostic factor for ductal cancers, we describe the expression of ADAM10 and ADAM17 in the pancreatic ductal epithelium. Altogether, the dynamic expression profile of the ADAM proteases described here may reflect a functional divergence of these as mediators of pancreas biology. Developmental Dynamics 232:1105–1114, 2005. © 2005 Wiley‐Liss, Inc.
Bioactivity of diopside ceramic in human parotid saliva
Authors: De Aza Piedad N. , Luklinska Zofia B. , Anseau Michel
Published: February 2005

Diopside ceramic pellets with a nominal composition of 55.5 wt % SiO2‐25.9 wt % CaO‐18.0 wt % MgO were soaked in human parotid saliva (HPS) over different time intervals, to investigate the behavior of the material in a natural medium of high protein content. The results showed the formation of a hydroxyapatite (HA)‐like layer on the surface of the ceramic, and suggested that the mechanism of HA‐like layer formation in saliva was similar to that showed in vitro test by other silica‐based materials. The HA‐like layer formed at the interface was found to be compact, continuous, and composed of many small crystallites with ultrastructure similar to that of natural cortical bone and dentine. The study concluded that the high pH conditions (9.8) existing right at the ceramic/human parotid saliva interface promoted HA‐like phase precipitation. At this stage of the study, it is possible to suggest that the diopside ceramic could be of interest in specific periodontal applications for bone restorative purposes. Morphology, structure, and composition of the interfacial reaction product were examined by Scanning and Transmission Electron Microscopy techniques (SEM and TEM), combined with Energy Dispersive X‐say Spectroscopy (EDS). Changes in ionic concentrations were measured using Inductively Coupled Plasma Atomic Emission Spectroscopy (ICP‐AES), while the pH right at the interface of diopside/PHS were determined with an Ion Sensitive Field Effect Transistor (ISFET‐Meter) instruments. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 73B: 54–60, 2005
Theoretical insights into the mechanism of acetylcholinesterase‐catalyzed acylation of acetylcholine
Authors: Manojkumar T. K. , Cui Chunzhi , Kim Kwang S.
Published: February 2005

Acylation of acetylcholine (ACh) catalyzed by acetylcholinesterase (AChE) has been studied using high‐level theoretical calculations on a model system that mimics the reaction center of the enzyme, and compared with uncatalyzed acylation reaction. The geometries of all the intermediates and transition states, activation energies, and solvent effects have been calculated. The calculations predict simultaneous formation of two short‐strong hydrogen bonds (SSHB) in the rate‐determining transition state structures [the first SSHB involves the hydrogen atom of Ser‐200 (Hs) and another involves the hydrogen atom of His‐440 (Hh)]. In the intermediate states, the H‐bond corresponding to Hhinvolves SSHB, whereas the one corresponding to Hsdoes not. © 2005 Wiley Periodicals, Inc. J Comput Chem 26: 606–611, 2005
The effect of aluminium coating on elemental signals in X‐ray microanalysis
Authors: Reid A. P. , Oates K. , Potts W. T. W.
Published: February 2005

It has been determined that, in the normal range of aluminium coating thicknesses used to remove charge from non‐conducting specimens in the electron microscope, no detectable influence on the elemental signals obtained in X‐ray microanalysis is observed. This is in contrast to a previous report (Hopkins et al., J. Electron Microsc. Tech., 18:176–182, 1991) of a reduction in elemental signal with increasing aluminium coating thickness. An explanation of errors in the previous interpretation is provided. © 1993 Wiley‐Liss, Inc.
Blood‐brain barrier permeability in rats is altered by exposure to magnetic fields associated with magnetic resonance imaging at 1.5 T
Authors: Prato Frank S. , Wills Jane M. , Roger J. , Frappier H. , Drost Dick J. , Lee Ting‐Yim , Shivers Richard R. , Zabel Pamela
Published: February 2005

We have previously reported that exposure of rats to low‐field (0.15 T) magnetic resonance imaging (MRI) increases blood‐brain barrier (BBB) permeability. However, a number of investigators have failed to observe this effect when high‐field MRI (1.5 T or higher) is used. Therefore, we investigated whether or not we would observe changes using our technique at these higher fields.

Adult male Sprague‐Dawley rats were anaesthetised and then exposed to a 22.5 min imaging or sham procedure. Immediately following exposure, rats were injected with 1 MBq of 153Gd‐DTPA intracardially and then immediately re‐exposed for an additional 22.5 min. The rats were killed 1h following the second MRI exposure, at which time the brain was resected and 3ml of venous blood collected. The ratio of radioactivity per gram of brain to radioactivity per per milliliter of blood, known as the brain‐blood partition coefficient, was determined and used as a measure of BBB permeability. Groups of animals had different exposures. Group 1 (n = 9) was exposed to a clinically relevant MRI procedure. Group 2 (n = 20) was exposed to the same procedure except the rf specific absorption rate (SAR) was reduced to 25% and the animals were positioned 15 cm from imager centre to increase the time‐varying magnetic field from 0.4 to 2.8 T/s. For the sham exposures (n = 21), the animals were placed in the imager with the static field ramped down to zero and exposed to a sound recording simulating a MRI examination. In a third group (n = 11), exposure to only the static 1.5 T was investigated, while in a fourth group (n = 15), the exposure field was only to a static 1.89 T. Sham controls for groups 3 (n = 12) and 4 (n = 19) were silent.

Group 1 showed an increase in BBB permeability (5.7 ± 0.5, mean ± SEM, P < 0.04, n = 9); however, group 2 showed a decrease (3.9 ± 0.2, P < 0.002, n = 20). Static field exposure of 1.5 T increased permeability (5.7 ± 0.5, P < 0.05, n = 11) as did 1.89 T (4.7 ± 0.4, P < 0.02, n = 15). Although there was no difference between sound and silent shams, shams done at night (4.8 ± 0.2, n = 32) were significantly greater (P < 0.0004) than those done during the day (3.7 ± 0.2, n = 19). Our results suggest changes in the rf and/or gradient field exposure can produce opposite effects on BBB permeability. Further, experiments involving only rf and only gradient field exposure are needed.

The estimation of changes in BBB permeability by measuring the partition coefficient of compounds normally excluded by the BBB offers an objective quantitative technique which can detect changes of the order of 25%. This sensitivity is needed to explore the important, albeit subtle, effects of magnetic fields. © 1994 Wiley‐Liss, Inc.
Combination of cobalt labelling with immunocytochemical reactions for electron microscopic investigations on frog spinal cord
Authors: Nagy István , Sik Attila , Polgár Erika , Petkó Mihály , Antal Miklós
Published: February 2005

Cobalt staining of primary afferents in frog spinal cord was combined with peroxidase‐antiperoxidase pre‐embedding or immunogold post‐embedding immunocytochemical labelling. Our results have shown that cobalt labelling can easily be distinguished from both of the immunoreaction end products. The protocol of cobalt labelling did not affect the immunoreactivity of structures. The morphology and synaptology of cobalt labelled and immunostained profiles in our sections were very similar to those reported in previous studies using different double labelling techniques. These results indicate that this new combined method could be used as an alternative double labelling technique in electron microscopic studies on nervous tissues. © 1994 Wiley‐Liss, Inc.
Direct determination of five fluoroquinolones in chicken whole blood and in veterinary drugs by HPLC
Authors: Samanidou Victoria F. , Christodoulou Eleni A. , Papadoyannis Ioannis N.
Published: February 2005

A direct, accurate, and sensitive chromatographic analytical method for the quantitative determination of five fluoroquinolones (enoxacin, ofloxacin, norfloxacin, ciprofloxacin, and enrofloxacin) in chicken whole blood is proposed in the present study. For quantitative determination lamotrigine was used as internal standard at a concentration of 20 ng/μL. The developed method was successfully applied to the determination of enrofloxacin, as the main component of commercially available veterinary drugs. Fluoroquinolone antibiotics were separated on an Inertsil (250×4 mm) C8, 5 μm, analytical column, at ambient temperature. The mobile phase consisted of a mixture of citric acid (0.4 mol L–1)–CH3OH–CH3CN (87 : 9 : 4% v/v) leading to retention times less than 14 min, at a flow rate 1.4 mL min–1. UV detection at 275 nm provided limits of detection of 2 ng/mL per 20 μL injected volume for enoxacin, norfloxacin, and ciprofloxacin, 0.4 ng/mL for ofloxacin, and 4 ng/mL for enrofloxacin. Preparation of chicken blood samples is based on the deproteinization with acetonitrile while the pharmaceutical drug was simply diluted with water. Peaks of examined analytes in real samples were identified by means of a photodiode array detector. The method was validated in terms of within‐day (n = 6) precision and accuracy after chicken whole blood sample deproteinization by CH3CN. Using 50 μL of chicken blood sample, recovery rates at fortification levels of 40, 60, and 80 ng ranged from 86.7% to 103.7%. The applicability of the method was evaluated using real samples from chicken under fluoroquinolone treatment.
Study of the Degradation of an Epoxy/Amine Resin, 2
Authors: Mailhot Bénédicte , Morlat‐Thérias Sandrine , Bussière Pierre‐Olivier , Gardette Jean‐Luc
Published: February 2005

Summary: The degradation behaviour of a flexible epoxy/amine resin has been studied. The resin, made of DGEBA and polyether diamine (Jeffamine® D2000) has been submitted to photooxidation, photolysis (in absence of oxygen) and thermooxidation experiments. The nature and the mechanism of formation of the products have been previously reported in the first paper of this series. In this paper, the rate of formation of the degradation products and their distribution within the sample are discussed. The change in the rate of degradation observed after 30 h of irradiation in artificial ageing at λ > 300 nm in the presence of oxygen, measured by ATR‐FTIR and UV‐Vis spectrometries, is explained by a large attenuation of light intensity by the chromophoric photoproducts formed. The photooxidation profiles measured by micro‐FTIR showed a heterogeneous distribution of the photoproducts in the first 250 μm of the exposed surface. The formation of these photoproducts is associated to chain scission reactions. This was clearly evidenced by the decrease of stiffness measured by AFM nanoindentations in the same first 250 μm.

Stiffness profiles measured by AFM nanoindentation of a photooxidised epoxy/amine sample.

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Stiffness profiles measured by AFM nanoindentation of a photooxidised epoxy/amine sample.
Study of the Degradation of an Epoxy/Amine Resin, 1
Authors: Mailhot Bénédicte , Morlat‐Thérias Sandrine , Ouahioune Mélanie , Gardette Jean‐Luc
Published: February 2005

Summary: The degradation of an epoxy/amine resin was studied under photolytic conditions in absence and in presence of oxygen and under thermooxidative conditions. The resin is obtained after curing the diglycidyl ether of bisphenol‐A (DGEBA) with a poly(propylene glycol) which is diamine terminated. The mechanisms of degradation of the two separate components before curing were also investigated. Analysis by IR and UV‐Vis spectroscopies revealed that the oxidation photoproducts detected during the degradation of the epoxy/amine result from the oxidation of the DGEBA part, of the amine crosslinks and, to a lower extent, of the poly(oxypropylene) units. Their mechanism of formation essentially involves chain scission reactions. During irradiation, the yellowing observed is mainly due to the formation of a quinone methide structure. Thermooxidation generates high discoloration with some products only generated in that case. For all experiments, a detailed analysis of the IR spectra is given with the chemical mechanisms of formation of the degradation products.

ATR‐IR spectra of an epoxy/amine sample in the carbonyl region during photooxidation.

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ATR‐IR spectra of an epoxy/amine sample in the carbonyl region during photooxidation.
Ultrarapid Molecular Release from Poly(N‐isopropylacrylamide) Hydrogels Perforated Using Silica Nanoparticle Networks
Authors: Kaneko Tatsuo , Asoh Taka‐aki , Akashi Mitsuru
Published: February 2005

Summary: Porous poly(N‐isopropylacrylamide) (PNIPAAm) hydrogels were successfully prepared in the presence of nanosized silica particles with network morphology and subsequent silica extraction by HF treatment. The nanosized pores induced very rapid deswelling of the hydrogels, accompanied by volume phase transitions from swelling to deswelling states at approximately 30 °C. Deswelling, which was analyzed by a quick change in temperature of the aqueous media from 20 to 40 °C, was facilitated by increased silica particle content. The deswelling rate constant of the hydrogel prepared using silica nanoparticles with a network morphology (NT gel) was about 1 900‐fold greater than that of nonporous hydrogels and 13‐fold larger than that of porous hydrogels perforated using spherical silica nanoparticles (SP gel). The releasing rate of the low‐molecular weight chromophore from the NT gel was higher than that from the SP gel. In the chromophore‐labeled macromolecules, the network morphology was effective for increasing the releasing rate based on the transfer inside the hydrogel, as well as for increasing the amount released based on the surface pore morphology.

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Novel Thermosetting Resins Based on 4‐(N‐Maleimido)phenylglycidylether, 4
Authors: Liu Ying‐Ling , Wang Yao‐Hsuan , Chen Hsueh‐Shih
Published: February 2005

Summary: A series of polymer‐clay nanocomposites were prepared by the simultaneous in situ curing of 4‐(N‐maleimido)phenylglycidylether/4,4‐diaminodiphenylmethane (MPGE/DDM) with the intercalation/exfoliation of various organo‐modified clays. The dispersion of the clays in the polymer matrix was produced by partial exfoliation and intercalation, as observed with X‐ray diffraction and transmission electronic microscopy. Clay modified with a carboxylic acid‐containing modifier showed enhancements with repesect to clay delamination in nanocomposite preparation. In comparison with the pristine resin, MPGE/DDM‐clay nanocomposites showed improved glass transition temperatures, thermal stability and flame retardance.

Preparation and characterization of polymer‐clay nanocomposites based on a new maleimide‐epoxy hybrid monomer.

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Preparation and characterization of polymer‐clay nanocomposites based on a new maleimide‐epoxy hybrid monomer.
IR Laser‐Induced Degradation of Poly(vinyl acetate): Novel Thermal Reactions in Solid Polymers
Authors: Kupčík Jaroslav , Blazevska‐Gilev Jadranka , Pola Josef
Published: February 2005

Summary: Pulsed‐IR laser‐induced decomposition of poly(vinyl acetate) (PVAC) differs remarkably from its conventional pyrolysis, which results in the formation of acetic acid and non‐polar carbonaceous residue. In contrast, the products in the former case are (i) vinyl acetate (low energy channel), (ii) products of cleavage in the acetate group, and (iii) an ablatively deposited polar polymeric film containing roughly half of the acetoxy groups initially present.

Schematic of the different routes of poly(vinyl acetate) degradation.

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Schematic of the different routes of poly(vinyl acetate) degradation.
Reply: Ciprofloxacin‐induced chorea
Authors: Post Bart , Koelman Johannes H.T.M. , Tijssen Marina A.J.
Published: February 2005

The original letter to which this reply refers was published in Movement DisordersMov Disord (2005) 20 (4) 513–514.
Anionic and cationic components from protein aggregates in bovine seminal plasma and their effects of sperm motility
Authors: Al‐Somai N. , C. Molan P. , Vishwanath R. , Shannon P.
Published: February 2005

Bovine seminal plasma proteins are in an aggregated form of high molecular weight in their native state. By immobilisation on a cation exchanger with exposure to disaggregating conditions (i.e., acetonitrile and low pH), the high‐molecular‐weight aggregates could be dissociated to slowly release the low‐molecular‐weight components. The anionic component released from the cation exchanger during disaggregation was collected by adsorption on a hydrophobic interaction column. The cationic component remaining on the cation exchanger was eluted with NaOH. Both components were found on gel permeation chromatography to be <5 kDa. SDS—PAGE of the various fractions showed that component of low molecular weight were still in an aggregated form.

These components resulting from the disaggregation process have detrimental effects on sperm motility and the effects were more substantial compared with that of whole seminal plasma. All the cationic components were significantly detrimental to sperm motility, especially the fractions of low molecular weight. The anionic fractions reduced sperm motility when in an aggregated state. The isolated anionic peptide was not detrimental in its free form. In all fractions the peptides tended to re‐aggregate to a higher molecular weight under neutral conditions, however, the isolated anionic peptide (molecular weight <1,500) failed to do so. © Wiley‐Liss, Inc.
Activation of a Gi protein in digitonin/cholate‐solubilized membrane preparations of mouse sperm by the Zona pellucida, an egg‐specific extracellular matrix
Authors: Ning Xiaoping , Ward Cynthia R. , Kopef Gregory S.
Published: February 2005

Mammalian sperm possess guanine nucleotide‐binding regulatory proteins (G proteins) that are involved in signal transduction pathways leading to zona pellucida (ZP)‐mediated acrosomal exocytosis. We have previously examined ZP‐G protein dynamics in mouse sperm homogenates, as well as cell‐free membrane preparations, and our data support the existence of ZP receptor‐G protein complexes in sperm membranes. However, the composition of this complex has not been identified due to experimental limitations of the membrane preparations. In the present study, a detergent‐solubilized preparation from mouse sperm membranes that retained the signaling properties of cell homogenates and cell‐free membrane preparations was developed using buffers containing digitonin and cholate. GTPγS, a poorly hydrolyzable analogue of GTP, bound to these solubilized preparations in a specific and concentration‐dependent fashion that reached saturation at 100 nM. Incubation of this solubilized membrane preparation with heat‐solubilized ZP resulted in an increase in specific GTPγS binding in a concentration‐dependent manner, with a maximal response at 4‐6 ZP/μl. Mastoparan (50 μM) increased GTPγS binding to levels similar to that seen with solubilized ZP. Mastoparan plus ZP stimulated GTPγS binding to the same extent as mastoparan or ZP alone. Pertussis toxin completely inhibited ZP‐stimulated GTPγS binding and decreased mastoparan‐stimulated GTPγS binding by 50–60%. Purified ZP3, the ZP component that possesses quantitatively all of the sperm binding and acrosomal exocytosis‐inducing activities of the intact ZP, stimulated GTPγS binding to an extent similar to that of solubilized ZP. The properties of this solubilized membrane preparation are similar to those found in the cell homogenates and cell‐free membrane preparations, suggesting that the components involved in ZP3‐mediated signal transduction are effectively solubilized and are responsive to the ZP3 ligand. © 1995 Wiley‐Liss, Inc.
Bovine oviduct‐specific glycoprotein: A potent factor for maintenance of viability and motility of bovine spermatozoa in vitro
Authors: Abe Hiroyuki , Sendai Yutaka , Satoh Takeshi , Hoshi Hiroyoshi
Published: February 2005

In the cow, a specific glycoprotein‐bovine oviduct‐specific glycoprotein (BOGP)‐is secreted by the epithelial cells of the oviduct at the follicular stage of the estrous cycle. In this study, we examined the effects of purified BOGP on the viability and motility of bovine spermatozoa in culture in vitro. Frozen‐thawed bovine spermatozoa were incubated in modified Tyrode's solution (TALP) that contained purified BOGP (TALP‐BOGP). In TALP‐BOGP, both the viability and motility of bovine spermatozoa were more effectively maintained than in the control medium without any added protein. The increases in both the viability and motility of spermatozoa were dose‐dependent. Spermatozoa were also incubated in TALP medium supplemented with bovine serum albumin, egg albumin, lactalbumin, or gastric mucin, and their viability and motility in these media were compared with that in TALP‐BOGP. Both the viability and motility of spermatozoa were more effectively maintained in TALP‐BOGP throughout a 12‐hr incubation than in other media tested. An immunolabeling study demonstrated that a monoclonal antibody specific for BOGP reacted with the posterior region of the head, the middle portion, and the tail of spermatozoa that had been incubated with TALP‐BOGP, suggesting that BOGP becomes specifically associated with particular regions of the spermatozoon. These results suggest that BOGP is a potent factor for maintenance of the viability and motility of sperm. On the basis of the present results, we also propose that BOGP may play an important role in sperm functions during the reproductive process. © 1995 wiley‐Liss, Inc.
An engineering approach to dynamic prediction of network performance from application logs
Authors: Abusina Zalal Uddin Mohammad , Zabir Salahuddin Muhammad Salim , Ashir Ahmed , Chakraborty Debasish , Suganuma Takuo , Shiratori Norio
Published: February 2005

Network measurement traces contain information regarding network behavior over the period of observation. Research carried out from different contexts shows predictions of network behavior can be made depending on network past history. Existing works on network performance prediction use a complicated stochastic modeling approach that extrapolates past data to yield a rough estimate of long‐term future network performance. However, prediction of network performance in the immediate future is still an unresolved problem. In this paper, we address network performance prediction as an engineering problem. The main contribution of this paper is to predict network performance dynamically for the immediate future. Our proposal also considers the practical implication of prediction. Therefore, instead of following the conventional approach to predict one single value, we predict a range within which network performance may lie. This range is bounded by our two newly proposed indices, namely, Optimistic Network Performance Index (ONPI) and Robust Network Performance Index (RNPI). Experiments carried out using one‐year‐long traffic traces between several pairs of real‐life networks validate the usefulness of our model. Copyright © 2005 John Wiley & Sons, Ltd.