bluuebunny/crossref_metadata_2025 huggingface dataset:
MEMS Device to Monitor Biological Oxygen Uptake at Arrays of Single Cells and Small Cell Clusters
Authors: Sheth Disha B. , Suresh Gayathri , Yang Jian , Ladas Thomas , Zorman Christian A. , Gratzl Miklós
Published: February 2008

Oxygen uptake by a cell is indicative of metabolic processes which are modulated by extracellular stimuli and is characteristic of a cell's physiological status. In this work, a MEMS platform with an array of microsensors to monitor these processes at cell constructs is being developed. An array of Pt microring electrodes has been fabricated to quantitatively assess oxygen uptake by normal and pharmacologically manipulated BAC1.2F5 macrophage cells positioned at cell attachment sites inside the microrings. An amperometric pulsing protocol was implemented to reduce interference with cellular metabolism caused by depletion of oxygen during the measurement. We were able to detect changes as small as 1% in oxygen concentration in the vicinity of single cells and small cell clusters. Thus, the approach can be used for sensitive indication of oxygen uptake by cell(s) and its modulation by environmental factors such as pharmacological agents, and interaction with adjacent cells. Moreover, parallel experiments at different cell attachment sites are made feasible by the sensor array. This can provide multiple data sets for biostatistics in the same amount of time that is required to get a single data set.
Enhanced system design for download and streaming services using Raptor codes
Authors: Gasiba Tiago , Xu Wen , Stockhammer Thomas
Published: February 2008

Raptor codes have been recently standardised by 3rd Generation Partnership Project (3GPP) to be used in the application layer (AL) for multimedia broadcast and multicast services (MBMS) including download delivery and streaming delivery. Furthermore, digital video broadcast (DVB) has also recommended the inclusion of these Raptor codes for IP‐datacast services. In this paper, enhancements on the system and receiver design using Raptor codes are studied, namely the permeable layer receiver (PLR) and the individual post‐repair mechanism. With the PLR, the partial information ignored in the conventional receiver is passed from lower layer to higher layer. We show how a practical and efficient implementation of the Raptor decoder as a PLR can be done, which can not only achieve huge performance gains, but the gains can be achieved at an affordable low decoding complexity. Whereas the PLR is employed for enhancing both download and streaming services, the post‐repair aims at guaranteeing reliable download delivery when a feedback channel is available. We propose here two efficient post‐repair algorithms which fully exploit the properties of the Raptor codes. One allows to find a minimum set of source symbols to be requested in the post‐delivery, and another allows to find a sufficient number of consecutive repair symbols. Selected simulations verify the good performance of proposed techniques. Copyright © 2008 John Wiley & Sons, Ltd.
Comparison of approaches for machine‐learning optimization of neural networks for detecting gene‐gene interactions in genetic epidemiology
Authors: Motsinger‐Reif Alison A. , Dudek Scott M. , Hahn Lance W. , Ritchie Marylyn D.
Published: February 2008

The detection of genotypes that predict common, complex disease is a challenge for human geneticists. The phenomenon of epistasis, or gene‐gene interactions, is particularly problematic for traditional statistical techniques. Additionally, the explosion of genetic information makes exhaustive searches of multilocus combinations computationally infeasible. To address these challenges, neural networks (NN), a pattern recognition method, have been used. One limitation of the NN approach is that its success is dependent on the architecture of the network. To solve this, machine‐learning approaches have been suggested to evolve the best NN architecture for a particular data set. In this study we provide a detailed technical description of the use of grammatical evolution to optimize neural networks (GENN) for use in genetic association studies. We compare the performance of GENN to that of a previous machine‐learning NN application—genetic programming neural networks in both simulated and real data. We show that GENN greatly outperforms genetic programming neural networks in data sets with a large number of single nucleotide polymorphisms. Additionally, we demonstrate that GENN has high power to detect disease‐risk loci in a range of high‐order epistatic models. Finally, we demonstrate the scalability of the GENN method with increasing numbers of variables—as many as 500,000 single nucleotide polymorphisms.Genet. Epidemiol. 2008. © 2008 Wiley‐Liss, Inc.
The Limits of Growth
Authors: Sander Martin , Hummel Jürgen , Klein Nicole , Clauss Marcus
Published: February 2008

Tracing the footsteps of giants: How the bodies of 50‐ton prehistoric dinosaurs worked and the evolutionary steps that led to this gigantic size
Moving Like Worms: Without “Legs”
Authors: Zimmermann Klaus
Published: February 2008

A copycat of nature: The use of magnetic fluids opens up innovative, entirely new high‐tech ways of creating an artificial worm. Worm‐like motion systems can be both useful and inspirational in a wide variety of technical applications
Redistribution or horizontal equity in Hong Kong's mixed public–private health system: a policy conundrum
Authors: Leung Gabriel M. , Tin Keith Y. K. , O'Donnell Owen
Published: February 2008

We examine the distributional characteristics of Hong Kong's mixed public–private health system to identify the net redistribution achieved through public spending on health care, compare the income‐related inequality and inequity of public and private care and measure horizontal inequity in health‐care delivery overall. Payments for public care are highly concentrated on the better‐off whereas benefits are pro‐poor. As a consequence, public health care effects significant net redistribution from the rich to the poor. Public care is skewed towards the poor in part not only because of allocation according to need but also because the rich opt out of the public sector and consume most of the private care. Overall, there is horizontal inequity favouring the rich in general outpatient care and (very marginally) inpatient care. Pro‐rich bias in the distribution of private care outweighs the pro‐poor bias of public care. A lesser role for private finance may improve horizontal equity of utilisation but would also reduce the degree of net redistribution through the public sector. Copyright © 2008 John Wiley & Sons, Ltd.
Energy metabolism transition in multi‐cellular human tumor spheroids
Authors: Rodríguez‐Enríquez Sara , Gallardo‐Pérez Juan Carlos , Avilés‐Salas Alejandro , Marín‐Hernández Alvaro , Carreño‐Fuentes Liliana , Maldonado‐Lagunas Vilma , Moreno‐Sánchez Rafael
Published: February 2008

It is thought that glycolysis is the predominant energy pathway in cancer, particularly in solid and poorly vascularized tumors where hypoxic regions develop. To evaluate whether glycolysis does effectively predominate for ATP supply and to identify the underlying biochemical mechanisms, the glycolytic and oxidative phosphorylation (OxPhos) fluxes, ATP/ADP ratio, phosphorylation potential, and expression and activity of relevant energy metabolism enzymes were determined in multi‐cellular tumor spheroids, as a model of human solid tumors. In HeLa and Hek293 young‐spheroids, the OxPhos flux and cytochrome c oxidase protein content and activity were similar to those observed in monolayer cultured cells, whereas the glycolytic flux increased two‐ to fourfold; the contribution of OxPhos to ATP supply was 60%. In contrast, in old‐spheroids, OxPhos, ATP content, ATP/ADP ratio, and phosphorylation potential diminished 50–70%, as well as the activity (88%) and content (3 times) of cytochrome c oxidase. Glycolysis and hexokinase increased significantly (both, 4 times); consequently glycolysis was the predominant pathway for ATP supply (80%). These changes were associated with an increase (3.3 times) in the HIF‐1α content. After chronic exposure, both oxidative and glycolytic inhibitors blocked spheroid growth, although the glycolytic inhibitors, 2‐deoxyglucose and gossypol (IC50 of 15–17 nM), were more potent than the mitochondrial inhibitors, casiopeina II‐gly, laherradurin, and rhodamine 123 (IC50 > 100 nM). These results suggest that glycolysis and OxPhos might be considered as metabolic targets to diminish cellular proliferation in poorly vascularized, hypoxic solid tumors. J. Cell. Physiol. 216: 189–197, 2008. © 2008 Wiley‐Liss, Inc.
Regulation of Na+/H+ exchanger 1 allosteric balance by its localization in cholesterol‐ and caveolin‐rich membrane microdomains
Authors: Tekpli Xavier , Huc Laurence , Lacroix Jérôme , Rissel Mary , Poët Mallorie , Noël Josette , Dimanche‐Boitrel Marie‐Thérèse , Counillon Laurent , Lagadic‐Gossmann Dominique
Published: February 2008

The Na+/H+ exchanger 1, which plays an essential role in intracellular pH regulation in most tissues, is also known to be a key actor in both proliferative and apoptotic processes. Its activation by H+ is best described by the Monod–Wyman–Changeux model: the dimeric NHE‐1 oscillates between a low and a high affinity conformation, the balance between the two forms being defined by the allosteric constant L0. In this study, influence of cholesterol‐ and caveolin‐rich microdomains on NHE‐1 activity was examined by using cholesterol depleting agents, including methyl‐β‐cyclodextrin (MBCD). These agents activated NHE‐1 by modulating its L0 parameter, which was reverted by cholesterol repletion. This activation was associated with NHE‐1 relocation outside microdomains, and was distinct from NHE‐1 mitogenic and hormonal stimulation; indeed MBCD and serum treatments were additive, and serum alone did not change NHE‐1 localization. Besides, MBCD activated a serum‐insensitive, constitutively active mutated NHE‐1 (625KDKEEEIRK635 into KNKQQQIRK). Finally, the membrane‐dependent NHE‐1 regulation occurred independently of Mitogen Activated Protein Kinases, especially Extracellular Regulated Kinase activation, although this kinase was activated by MBCD. In conclusion, localization of NHE‐1 in membrane cholesterol‐ and caveolin‐rich microdomains constitutes a novel physiological negative regulator of NHE‐1 activity. J. Cell. Physiol. 216: 207–220, 2008. © 2008 Wiley‐Liss, Inc.
Hepatocyte growth factor modulates Sertoli–Sertoli tight junction dynamics
Authors: Catizone A. , Ricci G. , Galdieri M.
Published: February 2008

In mammalian testes Sertoli cells form tight junctions whose function is fundamental for the maintenance of a normal spermatogenesis. Hepatocyte growth factor (HGF) is a cytokine influencing the cellular tight junctions either in normal or in tumor cells. We have previously demonstrated that HGF is expressed in the rat testis and influences many functional activities of somatic and germ cells. We now report that HGF decreases the levels of testicular occludin and influences the position of the molecule in the tight junctions as demonstrated by confocal microscopy analysis. In fact in the presence of the factor occludin was mainly localized in the suprabasal region of the tubules whereas in its absence occludin was prevalently localized in the basal region. Occludin production is known to be regulated by different cytokines including TGFβ. We have investigated the role of HGF in the regulation of the levels of TGFβ and we report that HGF significantly increases the amount of the active fraction of the factor without affecting the amount of the total TGFβ. Urokinase type plasminogen activator (uPA) is closely related with the tight junctions and is one of the molecules able to activate the inactive TGF‐β. We found that HGF significantly increases the amount of uPA present in the testis suggesting that HGF regulates the amount of active TGFβ via uPA levels. In conclusion we report that in the testis HGF regulates Sertoli–Sertoli tight junctions inducing a reduction and redistribution of occludin possibly modulating the levels of uPA and active TGFβ. J. Cell. Physiol. 216: 253–260, 2008. © 2008 Wiley‐Liss, Inc.
Comparison of atmospheric aqueous glycerol and steam explosion pretreatments of wheat straw for enhanced enzymatic hydrolysis
Authors: Sun Fubao , Chen Hongzhang
Published: February 2008

BACKGROUND: The oversupply of cheap glycerol by the oleochemicals industry together with problems occurring in low‐boiling‐point organosolv pretreatments, has generated an interest in the use of glycerol in the organosolv pretreatment of lignocellulosic biomass. Atmospheric aqueous glycerol autocatalytic organosolv pretreatment (AAGAOP) is a promising strategy that can effectively enhance enzymatic hydrolysis of lignocellulosic biomass. As a cost‐effective technique, steam explosion pretreatment (SEP) is being adopted in industrial applications. Accordingly, work has been carried out to investigate how AAGAOP enhanced enzymatic hydrolysis of lignocellulosic biomass compares with the SEP method.

RESULTS: Under controlled laboratory conditions, based on ≥ 90% cellulose recovery, AAGAOP removed ≥ 60% hemicellulose and ≥ 60% lignin from wheat straw while SEP led to ∼80% hemicellulose and 10% lignin removal. Enzymatic hydrolysis yields of AAGAOP and SEP reached ∼90% and ∼70%, respectively. Physical‐chemical structural characterization by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FT‐IR), helped explain the above results. The two methods gave priority to dissociating the guaiacyl lignin and had a relatively small effect on syringyl units. However, AAGAOP exhibited a superior performance.

CONCLUSION: The two methods enhanced the enzymatic hydrolysis of lignocellulosic biomass by removing and/or altering physical‐chemical structural impediments. The AAGAOP technique, with some special advantages, was more effective than SEP in enhancing the recovery and enzymatic digestibility of cellulose. Copyright © 2008 Society of Chemical Industry
Systematic study of β‐asarone‐rich volatile oil from Acori graminei rhizoma by off‐line supercritical CO2 extraction–gas chromatography–mass spectrometry
Authors: Dai Jian , Ha Chengyong , Shen Minmin
Published: February 2008

Supercritical CO2 extraction (SCE) technology was used to extract a volatile oil, rich in β‐asarone, from Acori graminei rhizoma (AGR). The effect of different extraction and fractionation parameters on oil yield and selectivity towards β‐asarone was investigated by SCE using commercial AGR samples. The optimal conditions (Pe/Te = 10 MPa/45°C; Pf1/Tf1 = 8 MPa/–10°C; Pf2/Tf2 = 2 MPa/10°C) gave a good oil yield and selectivity for β‐asarone. The extracts were also analyzed by GC–MS and compared with the volatile oil obtained by hydrodistillation, in which 39 main constituents including β‐asarone were found. Different cultivated AGR samples obtained from three areas of China were evaluated in terms of their volatile oil compositions obtained by extraction of commercial AGR samples under optimal conditions; the extract of the Guangdong (GD) sample showed a high β‐asarone content.
Optimized derivatization of acidic herbicides with trimethylsilyldiazomethane for GC analysis
Authors: Ranz Andreas , Korpecka Justyna , Lankmayr Ernst
Published: February 2008

In the present study, the preparation of methyl esters of chlorophenoxy acids with trimethylsilyldiazomethane (TMSD) is reported. TMSD is a mild and safe alternative to the highly toxic, thermally labile, and explosive diazomethane. Due to the novelty of this method, the characteristics of the reaction were investigated and the derivatization procedure was screened for statistically significant factors. The parameters identified as influential are the amount of methanol as well as reaction time and temperature. A careful optimization by a complete factorial response surface design was carried out to generate optimal reaction conditions with respect to maximum recovery and reaction yield. Special emphasis has been given to an accurate validation of the derivatization procedure. LODs were determined between 4.1 and 8.1 ng/mL for the enriched sample and linearity was proofed for more than five orders of magnitude. The applicability of the method was demonstrated by the analyses of quality control material including sample preparation with SPE. Polar herbicides investigated in the study belong to acetic acid (2,4‐D, MCPA, and 2,4,5‐T), butanoic acid (MCPB), and propanoic acid (mecoprop). An efficient, fast, and high‐throughput method for the determination of polar herbicides including the potential for automation is proposed.
gIsolation and purification of acetylshikonin and β‐acetoxyisovalerylshikonin from cell suspension cultures of Arnebia euchroma (Royle) Johnston using rapid preparative HPLC*
Authors: Sharma Nandini , Sharma Upendra Kumar , Malik Sonia , Bhushan Shashi , Kumar Vinod , Verma Subash Chandra , Sharma Naina , Sharma Madhu , Sinha Arun Kumar
Published: February 2008

Shikonin and its derivatives are important red colored naphthoquinone pigments found in a large number of Arnebia species, including A. euchroma, that are responsible for the various pharmacological activities exhibited by the plant. The precise separation of each naphthoquinone is essential for total quality evaluation and bioactivity analysis of herbal formulations of A. euchroma. Furthermore, the overexploitation of this useful plant has resulted in species becoming endangered. With this in mind, a simple and rapid preparative scale HPLC method with single compound recovery for the isolation and purification of two shikonin derivatives (i. e. acetylshikonin, β‐acetoxyisovalerylshikonin) from cell suspension cultures of A. euchroma is presented. The compounds were separated on a C18 column within 10 min using acetonitrile/methanol (95:5) as mobile phase in isocratic mode. The isolated compounds were found to be more than 98% pure. The LOD for acetylshikonin and β‐acetoxyisovalerylshikonin was estimated at 0.063 and 0.146 μg/mL, respectively, while the LOQ was found to be 0.209 and 0.487 μg/mL, respectively. The recoveries accomplished for both the shikonin derivatives were in the range of 94.7–96.8%. The repeatability, expressed as %RSD, of acetylshikonin and β‐acetoxyisovalerylshikonin was found to be 1.74 and 1.27, respectively.
One-way quantum computation via manipulation of polarization and momentum qubits in two-photon cluster states
Authors: Vallone G , Pomarico E , De Martini F , Mataloni P
Published: February 2008

Four-qubit cluster states of two photons entangled in polarization and linear momentum have been used to realize a complete set of single qubit rotations and the C-NOT gate for equatorial qubits with high values of fidelity. By the computational equivalence of the two degrees of freedom our result demonstrate the suitability of two photon cluster states for rapid and efficient one-way quantum computing.
Self-organized microvoid array perpendicular to the femtosecond laser beam in CaF2 crystals
Authors: Hu X , Qian B , Zhang P , Wang X , Su L , Qiu J , Zhu C
Published: February 2008

Microvoid arrays were self-organized when femtosecond laser beam was tightly focused at a fixed point inside CaF2 crystal sample. Expect the void array grown below the focal point which had been reported before, we found another void array grown vertical to the laser propagation direction. This result has potential application in the fabrication of integrated micro-optic elements and photonic crystals. The possible mechanism of the phenomenon was proposed and verified experimentally.
The effect of multiple language product descriptions on product evaluations
Authors: Gopinath Mahesh , Glassman Myron
Published: February 2008

This study investigates the influence of bilingual product packaging descriptions on product evaluation. In an experimental study, the evaluation of a product with an English‐only package is compared to the evaluation of the same product in a bilingual package. The evaluation of the product in the bilingual package is found to be significantly lower. Ethnocentrism and prejudice are investigated as possible explanations for this differential. The effect of the method of information processing used to evaluate the product (peripheral vs. central) is also explored. Both ethnocentrism and prejudice affect evaluations of a product in a bilingual package in a peripheral processing situation, but not in a central processing situation. © 2008 Wiley Periodicals, Inc.
Opinion leaders and followers: A replication and extension
Authors: Shoham Aviv , Ruvio Ayalla
Published: February 2008

Opinion leadership has been a central construct in studies of new product diffusion models. Flynn, Goldsmith, and Eastman (1996) introduced the related concept of opinion seeking and documented its measurement properties. This replication and extension paper examines these two concepts, using their original scales and placing them in a nomological model that includes innovativeness and computer and software use as antecedents. The research model is tested empirically using a convenience sample of 123 Israeli consumers, with regression models and a multiple discriminant analysis. Innovativeness and computer usage were found to explain opinion leadership and opinion seeking. Opinion leadership and opinion seeking predicted several computer‐related outcomes. The findings can be used to identify and utilize the differing information search profiles for opinion leaders and seekers. The former use a variety of sources, such as store visits and category‐specific newspapers and magazines. In contrast, seekers rely more on expert advice from opinion leaders. © 2008 Wiley Periodicals, Inc.
Pathogenicity of LRRK2 P755L variant in Parkinson's disease
Authors: Tan Eng‐King , Lim Hui‐Qin , Yuen Yih , Zhao Yi
Published: February 2008

A heterozygous 2264C→T variant (P755L) in LRRK2 gene has been reported to be a likely pathogenic variant among ethnic Chinese patients with Parkinson's disease (PD). In a case control study, we performed genetic analysis of the P755L variant in an independent cohort of Chinese patients with PD and controls. The P755L variant was present in 4/204 (2.0%) of PD compared with 6/235 (2.6%) of controls (odds ratio = 0.76, 95% CI 0.23, 2.6, P = 0.76). All subjects carried the heterozygous genotype. Subset analysis in the group ≥65 years of age revealed a prevalence of 2.8% in PD compared with 3.1% in controls (odds ratio = 0.92, 95% CI 022, 3.7, P = 0.9), and in the group <65 years of age showed a 0% in PD versus 2.1% in controls (P = 0.2). The phenotype of patients with PD with the P755L variant was generally similar to other patients with PD and none of the carriers reported a positive family history. The lack of functional data, absence of segregation of the variant with disease, and the presence of the variant in apparently healthy individuals suggest that P755L is possibly a rare polymorphism in the Chinese population. Further validation of our findings in other populations would be important. © 2008 Movement Disorder Society
Adult onset simple phonic tic after caudate stroke
Authors: Gomis Meritxell , Puente Victor , Pont‐Sunyer Claustre , Oliveras Carlos , Roquer Jaune
Published: February 2008

We describe a case of adult onset simple phonic tic after subcortical stroke involving left caudate nucleus. In the acute phase of stroke the patient presented a mild right clumsiness with complete recovery one week after onset. Within 3 weeks after stroke the patient noticed the gradual onset of involuntary simple phonic tic consisting of an “a” sound which persists. The patient did not present motor tics or the typical Tourette syndrome co‐morbidities, such as attention deficit or obsessive‐compulsive disorder. © 2008 Movement Disorder Society
A FETI‐based domain decomposition technique for time‐dependent first‐order systems based on a DAE approach
Authors: Nakshatrala K. B. , Hjelmstad K. D. , Tortorelli D. A.
Published: February 2008

We present a novel partitioned coupling algorithm to solve first‐order time‐dependent non‐linear problems (e.g. transient heat conduction). The spatial domain is partitioned into a set of totally disconnected subdomains. The continuity conditions at the interface are modeled using a dual Schur formulation where the Lagrange multipliers represent the interface fluxes (or the reaction forces) that are required to maintain the continuity conditions. The interface equations along with the subdomain equations lead to a system of differential algebraic equations (DAEs). For the resulting equations a numerical algorithm is developed, which includes choosing appropriate constraint stabilization techniques. The algorithm first solves for the interface Lagrange multipliers, which are subsequently used to advance the solution in the subdomains.

The proposed coupling algorithm enables arbitrary numeric schemes to be coupled with different time steps (i.e. it allows subcycling) in each subdomain. This implies that existing software and numerical techniques can be used to solve each subdomain separately. The coupling algorithm can also be applied to multiple subdomains and is suitable for parallel computers. We present examples showing the feasibility of the proposed coupling algorithm. Copyright © 2008 John Wiley & Sons, Ltd.
Flame retarding polyamide 6 with melamine cyanurate and layered silicates
Authors: Zhang Jin , Lewin Menachem , Pearce Eli , Zammarano Mauro , Gilman Jeffrey W.
Published: February 2008

The flammability behavior of the system polyamide 6 (PA 6) + melamine cyanurate (MC) with or without organically modified layered montmorillonite (OMMT) or sodium montmorillonite (Na+MMT) was studied. The high degree of flame retardancy (FR) obtained with 13 wt% MC is maintained upon adding up to 0.2 wt% OMMT or Na+MMT. Increase mass % of OMMT is antagonistic to the MC effect. The rate of dripping decreases while the size and mass of drops in the UL‐94 tests increases with increasing wt% OMMT indicating increase in viscosity of the melt and decrease in the rate of sublimation of melamine. Addition of poly vinyl pyrrolidone (PVP) decreases the viscosity and partially restores the FR rating. Na+MMT does not increase the viscosity and the FR ratings are partially preserved. The peak of heat release rate (PHRR) in the cone calorimeter decreases with increased loading of OMMT. Addition of Na+MMT or PVP has little influence on the PHRR. The time of ignition decreases with increase in OMMT, but is not affected when Na+MMT is used. This is explained by the low thermal conductivity of the clay containing surface layer of samples during pyrolysis and combustion. Mechanistic considerations are presented. Copyright © 2008 John Wiley & Sons, Ltd.
The individual fetal weight/estimated placental weight ratios in monochorionic twins with selective intrauterine growth restriction
Authors: Chang Yao‐Lung , Chang Shuenn‐Dyh , Chao An‐Shine , Hsieh Peter C. C. , Wang Chao‐Nin , Tseng Ling‐Hong
Published: February 2008

Objectives

To evaluate the individual fetal weight/estimated placental weight ratios (F/P ratio) of the two fetuses in monochorionic (MC) twins with selective intrauterine growth restriction (IUGR).

Material and Methods

MC twin with selective IUGR was defined as an estimated fetal weight below the 10th percentile in one twin of MC pregnancy. The estimated individual placental weight was obtained by cutting the placenta along the vascular equator into two territories. A total of 15 MC twins with selective IUGR and 18 MC twins without selective IUGR were included in this study.

Results

The individual F/P ratio in the IUGR twin is significantly higher than that in the appropriate for gestational age (AGA) one in MC twin with selective IUGR (6.4 vs 4.0 respectively, p < 0.001). In MC twin without IUGR, the F/P ratios are not significantly different between the two fetuses (5.4 vs 5.1, respectively).

Conclusion

The high F/P ratio in the IUGR twin in MC with selective IUGR may be due to the placental reserve phenomenon, so that a smaller placental territory may suffice to perfuse the IUGR twin. In other words, in MC twin gestations with an IUGR twin, the fetal weights are not proportional to the placental masses. Copyright © 2008 John Wiley & Sons, Ltd.
Effect of maternal smoking on prenatal screening for Down syndrome and trisomy 18 in the first trimester of pregnancy
Authors: Miron Pierre , Côté Yvan P. , Lambert Jean
Published: February 2008

Objectives

To assess the impact of maternal smoking on first‐trimester prenatal screening results for Down syndrome and trisomy 18.

Methods

Data on maternal smoking status, maternal age, gestational dating, levels of free beta‐human chorionic gonadotrophin (β‐hCG) and pregnancy‐associated plasma protein A (PAPP‐A) in maternal blood and fetal nuchal translucency (NT) thickness were analyzed from a cohort of 53 114 women. Statistical analyses were carried out for crude and adjusted comparisons between smoking and nonsmoking groups.

Results

In women who smoked during the first trimester of pregnancy, PAPP‐A and free β‐hCG levels from dried blood were significantly decreased (p < 0.001) and fetal NT thickness was significantly increased (p < 0.001). For an overall risk assessment combining maternal age and biochemical and ultrasound markers, no significant changes for Down syndrome were found with smoking, but significant increases in average risk as well as in positive rates were found for trisomy 18 (p < 0.001). A potential association between maternal smoking and trisomy 18 remains to be clarified.

Conclusion

Adjustment for smoking is recommended in first‐trimester prenatal screening for trisomy 18 and probably not warranted for Down syndrome because of the cancelling effects of decreased free β‐hCG and increased NT. Further research is required to demonstrate a biological association between maternal smoking and trisomy 18. Copyright © 2008 John Wiley & Sons, Ltd.
Expected performance of second trimester maternal serum testing followed by a ‘genetic sonogram’ in screening of fetal Down syndrome
Authors: Benn Peter A. , Egan James F. X.
Published: February 2008

Objective

To assess the efficacy of screening for fetal Down syndrome through the sequential provision of second trimester maternal serum tests and fetal ultrasound (the ‘genetic sonogram’).

Methods

Monte Carlo modeling was used to generate typical results for second trimester serum screening. Serum test likelihood ratios were then multiplied by likelihood ratios associated with the provision of a genetic sonogram. The impact of adding the genetic sonogram on the detection rate (DR) and false‐positive rate (FPR) were assessed for typical protocols that are currently in use. The effect of expanding the number of women who receive the genetic sonogram, variation in the marker frequencies in the genetic sonogram, and a multivariate Gaussian model that incorporated both serum and ultrasound measurements as continuous variables were also considered.

Results

When the genetic sonogram is offered only to those women who are screen‐positive by serum testing, there can be a substantial reduction in the number of women with an indication for amniocentesis but also some loss in detection. The extent of these changes will partially depend on the serum tests and cutoff used. Providing the genetic sonogram to more women can reduce loss in detection without resulting in high amniocentesis rates. As a sequential screening tool, the genetic sonogram can be improved by incorporating markers that have a high frequency in affected pregnancies and by using ultrasound measurements as continuous variables.

Conclusion

It should be possible to provide highly effective multistep screening protocols that maximize the benefits of both maternal serum and ultrasound while minimizing the amount of testing offered. Copyright © 2008 John Wiley & Sons, Ltd.
Smoking in pregnancy is associated with increased total maternal serum cell‐free DNA levels
Authors: Urato Adam C. , Peter Inga , Canick Jacob , Lambert‐Messerlian Geralyn , Pulkkinen Andrea , Knight George , Jeong Young‐Ju , Johnson Kirby L. , Bianchi Diana W.
Published: February 2008

Objective

Cell‐free DNA is a marker of cellular apoptosis and necrosis. We wished to determine if maternal smoking affects maternal and fetal serum cell‐free DNA levels.

Methods

Case–control sets of stored second‐trimester serum‐screening samples from 27 smoking and 90 nonsmoking pregnant women were developed. Smoking status was confirmed by measuring serum cotinine levels. Glyceraldehyde 3‐phosphate dehydrogenase (GAPDH) and DYS1 levels were determined using real‐time polymerase chain reaction (PCR) to measure total and fetal cell‐free DNA, respectively. At delivery, medical records were reviewed to confirm gender and determine other factors that could affect DNA values.

Results

Smoking was associated with significantly elevated GAPDH levels compared with nonsmokers (median: 97 662 genome equivalents (GE)/mL vs 38 217 GE/mL; p = 0.018). DYS1 levels were not statistically significantly elevated in smokers (p = 0.29). Other factors that affected DYS1 levels included maternal age in nonsmokers only (r2 = 0.30, p = 0.013) and maternal Synthroid use (p = 0.0045)

Conclusion

Pregnant smokers have threefold higher levels of total cell‐free DNA compared with pregnant nonsmokers. Maternal age and Synthroid exposure may also affect circulating cell‐free fetal DNA levels. Copyright © 2008 John Wiley & Sons, Ltd.
Correlation between referral ultrasound with suspected foetal anomalies and autopsy examination in two prenatal diagnosis centres. Impact of the routine use of 3D/4D scan
Authors: Picone Olivier , Levaillant Jean‐Marc , Hirt Raphael , Frydman René , Boulvain Michel , Senat Marie‐Victoire
Published: February 2008

Objective

To compare ultrasound diagnosis with autopsy findings in two tertiary referral foetal medicine centres, only one routinely using 3D and 4D ultrasound, and to compare results between the centres.

Methods

A retrospective study of 138 cases with a termination of pregnancy for foetal abnormalities after 21 weeks' gestation from January 2004 through May 2006 was carried out. We compared prenatal ultrasound and autopsy findings for each organ, calculating the sensitivity, specificity, positive predictive and negative predictive values, and false‐positive and false‐negative rates for ultrasound.

Results

Abnormalities were found most frequently in the brain (48.9%), heart and thorax (34.0%), limbs (31.9%), face (15.9%), and abdomen, urogenital tract and spine (14.5%). Sensitivity between centres did not differ statistically for the brain, spine, limbs and abdomen, but was different for the face (p = 0.005) and heart (p = 0.007). The detection rate was higher for facial malformations at the centre with routine 3D and 4D scans, and better for the heart and thorax at the other centre.

Conclusion

Diagnostic ultrasound cannot give a complete assessment of foetal anatomy. Autopsy examination is always strongly recommended for accurate genetic counselling. As already reported, 3D and 4D ultrasound may improve ultrasound performance in facial anomalies. Copyright © 2008 John Wiley & Sons, Ltd.
ADAM12s in maternal serum as a potential marker of pre‐eclampsia
Authors: Spencer Kevin , Cowans Nicholas J. , Stamatopoulou Anastasia
Published: February 2008

Objective

To examine whether maternal serum ADAM12s, a potential first‐ and second‐trimester marker of fetal aneuploidy and fetal growth, had altered concentrations in the first or second trimester of pregnancies subsequently developing pre‐eclampsia.

Methods

ADAM12s was measured by a time‐resolved fluoroimmunoassay developed by PerkinElmer Life Science. Maternal serum samples from women taking part in early first‐trimester aneuploidy screening in whom the pregnancy resulted in pre‐eclampsia (64) were identified from a cohort of 4390 singleton pregnancies in which uterine artery Doppler mean Pulsatility Index (PI) had been measured at 22–24 weeks. From amongst those cases delivering a normal term infant with birth weight greater than the 10th centile for gestational age 240 cases were selected as gestational age‐matched controls. A second study group consisting of maternal serum taken at 22–24 weeks at the time of uterine artery Doppler in a group of 12 women developing pre‐eclampsia were compared with 86 matched controls from a previously studied cohort of 24 cases and 144 controls. Serum ADAM12s concentrations were converted to multiple of the median (MoM) to take account of gestational age variation.

Results

First‐trimester maternal serum ADAM12s levels in women who developed pre‐eclampsia were reduced with a median MoM of 0.71 which was further reduced in those delivering prior to 35 weeks (0.50). At the 5th centile of normal (0.48 MoM) ADAM12s identified 27% of cases with pre‐eclampsia and 47% of those with early pre‐eclampsia. Combining ADAM12s with PAPP‐A from a previous study only resulted in a further 1% increase in detection of all women developing pre‐eclampsia. However combining ADAM12s with mean PI increased the detection rate to 66%. In the second trimester at 22–24 weeks the maternal serum ADAM12s levels were increased in those women developing pre‐eclampsia compared to controls (709 vs 486 ug/L, p = 0.045).

Conclusion

ADAM12s in addition to being a potential marker of aneuploidy may also be a marker of pre‐eclampsia. Further studies are required to see if this can improve on the clinical discrimination already provided by PAPP‐A in the early first trimester. Copyright © 2008 John Wiley & Sons, Ltd.
Sustainable use of glyphosate in North American cropping systems
Authors: Gustafson David I
Published: February 2008

Roundup Ready (glyphosate‐resistant) cropping systems enable the use of glyphosate, a non‐selective herbicide that offers growers several benefits, including superior weed control, flexibility in weed control timing and economic advantages. The rapid adoption of such crops in North America has resulted in greater glyphosate use and concern over the potential for weed resistance to erode the sustainability of its efficacy. Computer modeling is one method that can be used to explore the sustainability of glyphosate when used in glyphosate‐resistant cropping systems. Field tests should help strengthen the assumptions on which the models are based, and have been initiated for this purpose. Empirical evaluations of published data show that glyphosate‐resistant weeds have an appearance rate of 0.007, defined as the number of newly resistant species per million acres treated, which ranks low among herbicides used in North America. Modeling calculations and ongoing field tests support a practical recommendation for growers occasionally to include other herbicides in glyphosate‐resistant cropping systems, to lower further the potential for new resistance to occur. The presented data suggest that the sustainability of glyphosate in North America would be enhanced by prudent use of additional herbicides in glyphosate‐resistant cropping systems. Copyright © 2008 Society of Chemical Industry
On the properties of auxetic meta‐tetrachiral structures
Authors: Grima Joseph N. , Gatt Ruben , Farrugia Pierre‐Sandre
Published: February 2008

Auxetics are systems which get fatter when stretched and thinner when compressed i.e. they exhibit a negative Poisson's ratio. Here, we present an analysis of a novel class of structures (referred to as ‘meta‐chiral') which belong to the class of auxetics constructed using chiral building blocks. We show through analytical modelling that some of these systems can exhibit negative Poisson's ratios, the extent of which will depend, amongst other things, on the geometry of the system. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
On the auxetic properties of rotating rhombi and parallelograms: A preliminary investigation
Authors: Grima Joseph N. , Farrugia Pierre‐Sandre , Gatt Ruben , Attard Daphne
Published: February 2008

Auxetics exhibit the unusual property of expanding when uniaxially stretched (negative Poisson's ratio), a property that is usually linked to particular geometric features and deformation mechanisms. One of the mechanisms which results in auxetic behaviour is the one involving rotating rigid units, for which, systems made from triangles, squares or rectangles have already been considered. In this work we extend this study by considering systems which can be constructed from either connected rhombi or connected parallelograms. We show that various types of such systems can exist and we discuss in detail the properties of one type of ‘rotating rhombi' and one type of ‘rotating parallelograms'. We also show that the Poisson's ratio of these systems, which can be positive or negative, is anisotropic and dependent on the shape of the parallelograms/rhombi and the degree of openness of the system. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Initial growth of W‐based films deposited on Si studied with ARXPS
Authors: Oswald S. , Rittrich D. , Zahn W.
Published: February 2008

W and WN films with thicknesses of less than one monolayer up to some nanometers were deposited by magnetron sputtering. The samples were transferred after deposition immediately into an analysis chamber without breaking the vacuum to avoid oxide formation and contamination. Analysis was done by means of XPS for elemental and bonding state characterization and angle‐resolved XPS (ARXPS) for nondestructive depth profiling. Phase formation and morphology were studied during the first stages of layer growth. Influences of the residual gas atmosphere are discussed. Copyright © 2008 John Wiley & Sons, Ltd.
The morphological, optical and electrical properties of SnO2:F thin films prepared by spray pyrolysis
Authors: Zhi Xiao , Zhao Gaoyang , Zhu Tao , Li Ying
Published: February 2008

Combining the spray pyrolysis and the sol–gel techniques gives the possibility to produce Fluorine doped Tin oxide (SnO2:F) thin films. Transparent conducting SnO2:F thin films have been deposited on glass substrates by the spray pyrolysis technique. This technique for the fabrication of SnO2:F filmsby combining sol–gel process and the spray pyrolysis technique ispresented in this paper. The Sol–gel precursors have been successfully prepared using SnCl2·5H2O and (Ac)F3. The structural, electrical, and optical properties of these films were investigated. The high resolution transmission electron microscopy (HRTEM) and selected area diffraction (SAD) patterns of SnO2:F films show that the gel films lead to a tetragonal structure. The X‐ray diffraction pattern of the films deposited at substrate temperature 530° , the orientation of the films was predominantly [110]. In addition, the surface chemical components were also examined by X‐ray photoelectron spectroscopy (XPS) showing the SnO2:F deposited with the atomic concentration ratios Sn/F 1.82:1. The minimum sheet resistance was 50 Ω and average transmission in the visible wavelength range of 300 to 800 nm was 87.25%. Copyright © 2008 John Wiley & Sons, Ltd.
Contact angle and biocompatibility of sol‐gel prepared TiO2 thin films for their use as semiconductor‐based cell‐viability sensors
Authors: Ozasa Kazunari , Nemoto Shigeyuki , Li Yuanzhi , Hara Masahiko , Maeda Mizuo , Mochitate Katsumi
Published: February 2008

We have investigated the surface, biocompatibility, and H2O2 sensitivity of TiO2 thin films prepared by sol‐gel technique, from the viewpoints of aptitude for a gate‐oxide film on field‐effect transistors (FETs) for cell‐viability sensors. The surface of TiO2 thin films had nanometer‐scale roughness (approximately 1 nm in height), but was uniform and flat in micrometer scale. The contact angle of the TiO2 thin films increases with time, when the TiO2/GaAs samples were preserved in air at room temperature, probably because of hydrophobic contaminates. A stretched exponential dependence fits well to the temporal evolution of the TiO2 contact angle. Scattered data obtained in cell‐adhesion experiments show that the cell adhesion is mostly independent of the contact angle of the TiO2 surfaces. In order to evaluate TiO2 thin films for biosensor use, TiO2 thin films were formed on two‐dimensional electron‐gas (2DEG) FETs as the gate‐oxide film. TiO2/2DEG‐FETs exhibit a high H2O2 sensitivity up to 4.5 mV/µM, whereas conventional ISFET (Ta2O5/Si‐FET)is insensitive to H2O2. Copyright © 2008 John Wiley & Sons, Ltd.
Characterisation of the silicon nitride thin films deposited by plasma magnetron
Authors: Batan A. , Franquet A. , Vereecken J. , Reniers F.
Published: February 2008

Silicon nitride thin films were deposited by reactive DC magnetron sputtering on different substrates in a home‐made planar DC sputtering system. The sputtering was performed from a silicon target in a sputtering atmosphere of (Ar, H2, N2) mixture. The gas composition could be varied from 0 to 100% for Ar and N2, and from 0 to 10% for H2. The structure and purity of the coatings have been investigated as a function of the process parameters, such as the composition of the sputtering atmosphere and the total pressure. The deposited films were characterised by optical interferometry (thickness measurement), Fourier transformed infrared spectroscopy (FTIR), X‐ray diffraction (XRD) and XPS. The XPS spectra indicated that Si3N4 was obtained for a molar fraction of nitrogen larger than 0.1, and also indicated that the sputtered silicon nitride films were uncontaminated with oxygen and carbon. The N/Si ratio of the nitride films could be tuned between 0.56 and 1.33 depending on the deposition conditions. The presence of the transverse optical (TO) and longitudinal optical (LO) phonons in infrared reflection absorption spectroscopy (IRRAS) attest for the presence of SiN bonds. For the stoichiometric films no change in the LO phonon peak position was observed, indicating that there is no variation in the film composition. Copyright © 2008 John Wiley & Sons, Ltd.
Electrochemical studies on the stability and corrosion resistance of new zirconium‐based alloys for biomedical applications
Authors: Branzoi Ioan Viorel , Iordoc Mihai , Codescu Mirela
Published: February 2008

The biocompatibility of commercially pure zirconium and its alloys is closely related to their surface properties with both the composition of the protecting oxide film and the surface topography playing an important role. This article is a study of corrosion behavior of new zirconium alloys for orthopedic implants, which are supposed to be used instead of some implant materials that have a higher citotoxicity. For this reason, zirconium and its alloys will be employed widely in biomedical applications. The higher stability and corrosion resistance exhibited by zirconium are due to the spontaneous formation of a passive zirconium oxide film, which protects the metal from further oxidation. Potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) are used as electrochemical techniques. Measurements were carried out to investigate the corrosion behavior of zirconium and Zr2.5Nb, Zr3Ta, and Zr2.5Nb3Ta alloys in aerated Hank solution at 37 ± 0.2 °C. The results of EIS were compared with those obtained by potentiodynamic polarization techniques. Impedance spectra were represented both in complex impedance diagram (Nyquist plot) and Bode plots. The EIS measurements have confirmed this stability range and pointed out the formation of oxide layers on the electrode surfaces. Copyright © 2008 John Wiley & Sons, Ltd.