bluuebunny/crossref_metadata_2025 huggingface dataset:
Consumer Evaluations of Competing Brands: Perceptual versus Predictive Validity
Authors: Woodside Arch G.
Published: May 2012

This study applies the concepts of consumer predictive and confidence values of information to consumer evaluations of food quality. Examining hypothetical findings from a thought experiment, the study offers advances in cue utilization, predictive validity, and achievement of consumer's perceived quality and actual quality. Separately, metrics for these concepts were applied in a consumer product‐quality evaluation study of three brands of peanut butter. Actual quality was operationally defined in terms of Consumers Union ratings of the peanut butter. Using a between‐groups, posttest only experimental design, female graduate students (n = 98) tasted and rated one of three peanut butters on the basis of quality and nine product attributes. These informants received no knowledge of brand names or comparative qualities prior to the test. The analysis indicates a nonsignificant correlation between actual quality of the brands and quality as perceived by the informants. The major cues used by informants in making their qualitative judgments (cue utilization) differed from the significant dimensions associated with actual quality (predictive validity). The findings inform the suggestion for consumer training in the process of making accurate quality evaluations.
Movement disorders in autoimmune diseases
Authors: Baizabal‐Carvallo José Fidel , Jankovic Joseph
Published: May 2012

Movement disorders have been known to be associated with a variety of autoimmune diseases, including Sydenham's chorea, pediatric autoimmune neuropsychiatric disorders associated with streptococcus, systemic lupus erythematosus, antiphospholipid syndrome, gluten sensitivity, paraneoplastic and autoimmune encephalopathies. Tremors, dystonia, chorea, ballism, myoclonus, parkinsonism, and ataxia may be the initial and even the only presentation of these autoimmune diseases. Although antibodies directed against various cellular components of the central nervous system have been implicated, the pathogenic mechanisms of these autoimmune movement disorders have not yet been fully elucidated. Clinical recognition of these autoimmune movement disorders is critically important as many improve with immunotherapy or dietary modifications, particularly when diagnosed early. We discuss here the clinical features, pathogenic mechanisms, and treatments of movement disorders associated with autoimmune diseases, based on our own experience and on a systematic review of the literature. © 2012 Movement Disorder Society
Attenuated heart rate response in REM sleep behavior disorder and Parkinson's disease
Authors: Sorensen Gertrud Laura , Kempfner Jacob , Zoetmulder Marielle , Sorensen Helge B. D. , Jennum Poul
Published: May 2012

The objective of this study was to determine whether patients with Parkinson's disease with and without rapid‐eye‐movement sleep behavior disorder and patients with idiopathic rapid‐eye‐movement sleep behavior disorder have an attenuated heart rate response to arousals or to leg movements during sleep compared with healthy controls. Fourteen and 16 Parkinson's patients with and without rapid‐eye‐movement sleep behavior disorder, respectively, 11 idiopathic rapid‐eye‐movement sleep behavior disorder patients, and 17 control subjects underwent 1 night of polysomnography. The heart rate response associated with arousal or leg movement from all sleep stages was analyzed from 10 heartbeats before the onset of the sleep event to 15 heartbeats following onset of the sleep event. The heart rate reponse to arousals was significantly lower in both parkinsonian groups compared with the control group and the idiopathic rapid‐eye‐movement sleep behavior disorder group. The heart rate response to leg movement was significantly lower in both Parkinson's groups and in the idiopathic rapid‐eye‐movement sleep behavior disorder group compared with the control group. The heart rate response for the idiopathic rapid‐eye‐movement sleep behavior disorder group was intermediate with respect to the control and the parkinsonian groups. The attenuated heart rate response may be a manifestation of the autonomic deficits experienced in Parkinson's disease. The idiopathic rapid‐eye‐movement sleep behavior disorder patients not only exhibited impaired motor symptoms but also incipient autonomic dysfunction, as revealed by the attenuated heart rate response. © 2012 Movement Disorder Society
Three‐dimensional first‐pass myocardial perfusion MRI using a stack‐of‐spirals acquisition
Authors: Shin Taehoon , Nayak Krishna S. , Santos Juan M. , Nishimura Dwight G. , Hu Bob S. , McConnell Michael V.
Published: May 2012

Three‐dimensional cardiac magnetic resonance perfusion imaging is promising for the precise sizing of defects and for providing high perfusion contrast, but remains an experimental approach primarily due to the need for large‐dimensional encoding, which, for traditional 3DFT imaging, requires either impractical acceleration factors or sacrifices in spatial resolution. We demonstrated the feasibility of rapid three‐dimensional cardiac magnetic resonance perfusion imaging using a stack‐of‐spirals acquisition accelerated by non‐Cartesian k‐t SENSE, which enables entire myocardial coverage with an in‐plane resolution of 2.4 mm. The optimal undersampling pattern was used to achieve the largest separation between true and aliased signals, which is a prerequisite for k‐t SENSE reconstruction. Flip angle and saturation recovery time were chosen to ensure negligible magnetization variation during the transient data acquisition. We compared the proposed three‐dimensional perfusion method with the standard 2DFT approach by consecutively acquiring both data during each R–R interval in cardiac patients. The mean and standard deviation of the correlation coefficients between time intensity curves of three‐dimensional versus 2DFT were 0.94 and 0.06 across seven subjects. The linear correlation between the two sets of upslope values was significant (r = 0.78, P < 0.05). Magn Reson Med, 2013. © 2012 Wiley Periodicals, Inc.
Segmentation propagation using a 3D embryo atlas for high‐throughput MRI phenotyping: Comparison and validation with manual segmentation
Authors: Norris Francesca C. , Modat Marc , Cleary Jon O. , Price Anthony N. , McCue Karen , Scambler Peter J. , Ourselin Sebastien , Lythgoe Mark F.
Published: May 2012

Effective methods for high‐throughput screening and morphometric analysis are crucial for phenotyping the increasing number of mouse mutants that are being generated. Automated segmentation propagation for embryo phenotyping is an emerging application that enables noninvasive and rapid quantification of substructure volumetric data for morphometric analysis. We present a study to assess and validate the accuracy of brain and kidney volumes generated via segmentation propagation in an ex vivo mouse embryo MRI atlas comprising three different groups against the current “gold standard”—manual segmentation. Morphometric assessment showed good agreement between automatically and manually segmented volumes, demonstrating that it is possible to assess volumes for phenotyping a population of embryos using segmentation propagation with the same variation as manual segmentation. As part of this study, we have made our average atlas and segmented volumes freely available to the community for use in mouse embryo phenotyping studies. These MRI datasets and automated methods of analyses will be essential for meeting the challenge of high‐throughput, automated embryo phenotyping. Magn Reson Med, 2013. © 2012 Wiley Periodicals, Inc.
On shimming approaches in 3T breast MRI
Authors: Hancu Ileana , Govenkar Ambey , Lenkinski Robert E. , Lee Seung‐Kyun
Published: May 2012

A comparative study is presented, analyzing quantitatively the impact of 15 shim strategies on the homogeneity of the main magnetic field over the three‐dimensional breast region in 3T MRI. The results obtained in 12 female volunteers, spanning a wide range of body and breast types, indicate that the inclusion of the back and heart in the shim region of interest leads to considerable decrease in field homogeneity, and needs to be avoided. Comparison between shim strategies using volumetric B0 maps, covering the entire breast region, and 1–6 plane B0 maps indicate only minimally reduced performance for the latter. Interestingly, however, no single shim strategy relying on a limited number of B0 maps as input was found to work best in all volunteers. This was attributed to the limited capability of a small number of B0 maps to capture the B0 variability existent within breast. On the average, a rectangular shim region of interest, encompassing the breast region alone, worked best for the cohort studied here. Magn Reson Med, 2013. © 2012 Wiley Periodicals, Inc.
Adapting MRI acoustic radiation force imaging for in vivo human brain focused ultrasound applications
Authors: Kaye Elena A. , Pauly Kim Butts
Published: May 2012

A variety of magnetic resonance imaging acoustic radiation force imaging (MR‐ARFI) pulse sequences as the means for image guidance of focused ultrasound therapy have been recently developed and tested ex vivo and in animal models. To successfully translate MR‐ARFI guidance into human applications, ensuring that MR‐ARFI provides satisfactory image quality in the presence of patient motion and deposits safe amount of ultrasound energy during image acquisition is necessary. The first aim of this work was to study the effect of motion on in vivo displacement images of the brain obtained with 2D Fourier transform spin echo MR‐ARFI. Repeated bipolar displacement encoding configuration was shown less sensitive to organ motion. The optimal signal‐to‐noise ratio of displacement images was found for the duration of encoding gradients of 12 ms. The second aim was to further optimize the displacement signal‐to‐noise ratio for a particular tissue type by setting the time offset between the ultrasound emission and encoding based on the tissue response to acoustic radiation force. A method for measuring tissue response noninvasively was demonstrated. Finally, a new method for simultaneous monitoring of tissue heating during MR‐ARFI acquisition was presented to enable timely adjustment of the ultrasound energy aimed at ensuring the safety of the MR‐ARFI acquisition. Magn Reson Med, 2013. © 2012 Wiley Periodicals, Inc.
Fast joint design method for parallel excitation radiofrequency pulse and gradient waveforms considering off‐resonance
Authors: Yoon Daehyun , Fessler Jeffrey A. , Gilbert Anna C. , Noll Douglas C.
Published: May 2012

A fast parallel excitation pulse design algorithm to select and to order phase‐encoding (PE) locations (also known as “spokes”) of an Echo‐Volumar excitation k‐space trajectory considering B0 field inhomogeneity is presented. Recently, other groups have conducted research to choose optimal PE locations, but the potential benefit of considering B0 field inhomogeneity during PE location selection or their ordering has not been fully investigated. This article introduces a novel fast greedy algorithm to determine PE locations and their order that takes into account the off‐resonance effects. Computer simulations of the proposed algorithm for B1 field inhomogeneity correction demonstrate that it not only improves excitation accuracy but also provides an effective ordering of the PE locations. Magn Reson Med, 2012. © 2012 Wiley Periodicals, Inc.
Low‐profit Limited Liability Companies (L3Cs)
Authors: Artz Nancy , Gramlich Jeffrey , Porter Terry
Published: May 2012

This paper introduces the Low‐profit Limited Liability Company (L3C) form to the public affairs literature. The L3C is a new legal form of business entity emerging in the USA. As a form of social enterprise, L3C firms use a marketplace approach to solve social problems. The L3C form represents a radical transformation of capitalist enterprise, in that a social mission trumps profit generation. The emergence of the social enterprise movement has the potential to shift stakeholder expectations about appropriate levels of corporate social responsibility. If changes in tax policy occur, private foundations could become a major source of start‐up capital for L3Cs. The result would be social enterprise claiming a larger share of commercial marketplaces. This paper explores L3C opportunities and risks from a managerial perspective, with particular focus on the public affairs implications of the L3C form. Copyright © 2012 John Wiley & Sons, Ltd.
Semen analysis in adolescent cancer patients prior to bone marrow transplantation: When is it too late for fertility preservation?
Authors: Nahata Leena , Cohen Laurie E. , Lehmann Leslie E. , Yu Richard N.
Published: May 2012

Background

Sperm banking is an effective method of fertility preservation in adolescent boys with cancer but is strikingly underutilized, partly due to inconsistencies in fertility counseling and unclear guidelines regarding who should bank sperm. Patients undergoing bone marrow transplantation (BMT) are of particular interest given the high risk of infertility in this population.

Procedure

We reviewed the charts of male cancer patients who underwent BMT at age ≥13 years at the Dana‐Farber Cancer Institute (DFCI) from 2003 to 2010 to determine the number of fertility preservation attempts prior to initial treatment and/or BMT, and the outcomes of those sperm banking attempts.

Results

Sixty‐eight male cancer patients who had a BMT at age ≥13 years at the DFCI from 2003 to 2010 were included in the analysis. Six patients had attempted sperm banking prior to initial therapy. Thirty‐three patients attempted to bank prior to BMT; of those, 39% were azoospermic and 15% were oligospermic. Nineteen patients did not attempt to bank, and in 13 patients the decision to bank was unclear.

Conclusions

A more consistent approach to fertility counseling is essential for adolescent cancer patients. Though first line therapy may be low‐risk in terms of long‐term impact on fertility, our results demonstrate that transient gonadal dysfunction is common and ongoing chemotherapy may affect spermatogenesis. Should a patient undergo BMT during this period, sperm banking is unlikely to be successful; initial fertility risk assessment should account for this possibility. Pediatr Blood Cancer 2013; 60: 129–132. © 2012 Wiley Periodicals, Inc.
Viscoelasticity behaviors of lightly cured natural rubber/zinc dimethacrylate composites
Authors: Chen Yukun , Xu Chuanhui , Wang Yanpeng
Published: May 2012

Zinc dimethacrylate (ZDMA) can be polymerized during peroxide curing to form the polymerized ZDMA (PZDMA) at nanoscales. At the same time, the covalent crosslink of the rubber matrix and ionic crosslink introduced by the graft‐PZDMA also are formed. The structure evolution of this type of composites is complex. In this article, the dynamic viscoelasticity characteristics of lightly cured ZDMA/natural rubber (NR) composites were investigated using a Rubber Process Analyzer 2000 (RPA2000). Our goal was to study the internal structures of this type of composites in an early curing stage. The dynamical viscoelasticity of the composites cured for 1 min was focused. The results of RPA2000 indicated that the PZDMA could act as particles to form a strong filler–filler structure which resulted in apparent Payne effect. A “primary network” structure might be formed which contained covalent crosslink points, ionic crosslinks, physical adsorption, and PZDMA. The stress‐softening behavior was also investigated. At last, the scanning electron microscope analysis verified that most of the ZDMA had been polymerized to form PZDMA “nanoparticle” when the composites were cured for 1 min. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers
Statistical modeling for the accumulation of transverse matrix cracking in cross‐ply laminates
Authors: Wang Fang , Li Lu , Chen Zhiqian , Zeng Xiangguo
Published: May 2012

A statistical model has been proposed to predict the evolution of matrix cracking in the transverse lamina of cross‐ply laminates subjected to longitudinal tensile loading. The analytical model is based on a fracture mechanics approach which considers that the critical fracture toughness Gc of the 90° layers is not a constant but follows a Weibull distribution. Monte‐Carlo simulation technique is applied to predict the initiation and propagation of transverse cracking in terms of applied stress versus crack density. The effects of the thickness of the 90° layers on progressive damage and failure are also discussed in this study. Good agreements are reached between simulation and experimental results. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers
Tear behavior of polyester‐based coated textiles after thermo‐oxidative aging
Authors: Triki Ennouri , Arrieta Carlos , Boukehili Hychem , Vu‐Khanh Toan
Published: May 2012

In this article, a new method to characterize the tear behavior of coated textiles using fracture mechanics is proposed. The energy dissipated in tearing (EDT) of as‐received and thermally aged samples of polyester fabric, polyvinyl acetate rubber coating, and textile‐coating composites was calculated and compared. The EDT of the coated fabric displayed a slightly smaller value than the fabric alone, whereas the EDT of the coating was found to be negligible when compared with the other two. The presence of the coating is believed to have a detrimental effect on the tearing behavior of the coated fabric as it hinders interfilament slippage. A master curve of EDT retention vs. aging time for noncoated and coated fabric samples was constructed using the time–temperature superposition principle and fitted using the Hill equation. Fourier transform infrared analyses carried out on aged fabric samples hinted at a possible chain scission process, whereas the crystallinity of fabric samples, calculated via differential scanning calorimetry, was found to decrease after thermal aging. Scanning electron microscopy images revealed an increase in surface roughness after aging that may reduce interfilament friction. These results, coupled to an increase in the adhesion strength between fabric and coating, are likely the cause of the reduction of EDT noticed in aged coated and noncoated fabrics compared with as‐received ones. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers
Polyamide 6–wheat straw composites: Effects of additives on physical and mechanical properties of the composite
Authors: Amintowlieh Yasaman , Sardashti Amirpouyan , Simon Leonardo C.
Published: May 2012

Polyamide 6 was modified with lithium chloride (LiCl) salt and N‐butyl benzenesulfonamide (N‐BBSA) plasticizer (additives). The modification was done in order to develop an environmentally friendly composite, composed of wheat straw (WS). A 15 wt% of ground WS was compounded with Polyamide 6 along with the additives. Addition of LiCl decreased the melting point of the matrix, allowing for a lower compounding temperature. However, a pseudo‐crosslinking formation upon addition of salt limited the polymer chain movement and restricted the processing temperature. LiCl addition increased the tensile and flexural modulus of the composite, but decreased the tensile and flexural strength. Decrease in the strength was found to be related to the increase in the residence time of material during extrusion causing severe WS thermal degradation. Addition of N‐BBSA eased the processing due to lubrication effect, however, when used in excess, lowered the flexural modulus and strength. Addition of WS to Polyamide 6 increased the modulus of the matrix. Matrix tensile modulus and flexural modulus were enhanced by 27%; however, a decrease in strength of the matrix was obtained. Addition of WS, LiCl, and plasticizer lowered the impact properties of Polyamide 6. It was concluded that combination of 2 wt% LiCl and of 2 wt% N‐BBSA gives the best mechanical properties. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers
Studies on the viscoelasticity of poly(trimethylene terephthalate)/poly(ethylene–octene)/organomontmorillonite nanocomposites
Authors: Liu Feng , Zhong Yu , Jiang Chunyan , Wang Dong , Wang Zeng‐Kun , Run Ming‐Tao
Published: May 2012

The viscoelasticity of poly(trimethylene terephthalate)/maleinized poly(octene‐ethylene) copolymer/organomontmorillonite (OMMT) nanocomposites were investigated at both liquid and glassy states by using the rotational rheometer and dynamic mechanical analysis, respectively. The viscoelasticity results suggest that OMMT has many important influences on the structure, modulus, toughness, and cold‐crystallization of the nanocomposites. The OMMT has a strip‐like sheet morphology in the polymer matrix and when OMMT content increases to 4 wt%, the physical network‐like structure begins to form in the nanocomposites. The pseudoplasticity of the melts is increased by OMMT. In addition, the complex viscosity, storage modulus, and viscous behavior of the melts are increased with increasing OMMT content. The creep resistance of the nanocomposites is improved by OMMT, and it plays an important role on reinforcing the melts. The stress relaxation of the melts suggests that the nanofillers can not only enhance the interfacial interactions of the nanocomposites but also inhibit the recovery of the polymer chain segments. At glassy state, the nanocomposites' storage modulus increases with increasing OMMT content. As glass transition occurs, the loss factor and loss modulus suggest that OMMT toughens the polymer matrix. At rubber‐elastic state, OMMT depresses the cold‐crystallization of the polymer matrix due to its limitation effect on the motion of molecular chains. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers
Morphology, thermal, and dynamic mechanical properties of poly(lactic acid)/sisal whisker nanocomposites
Authors: Ahmad E.E.M. , Luyt A.S.
Published: May 2012

Sisal whiskers were used as biobased nanofillers to prepare poly(lactic acid) (PLA)‐based nanocomposites. The whiskers were prepared from sisal fibers via sulfuric acid hydrolysis. Freeze drying of the aqueous whisker suspension was carried out to obtain loosely packed dry sisal whiskers. The nanocomposites were prepared by melt mixing, followed by hot melt pressing. The effect of the freeze drying of the nanofibers, the treatments of the samples with maleic anhydride (MA)/dicumyl peroxide (DCP) and with DCP, and the premixing of the powdered components on the dispersion of the whiskers in the PLA matrix and on the morphology, as well as the thermal and dynamic mechanical properties, of the resultant nanocomposites were investigated. Transmission electron microscopy micrographs show that the acid hydrolysis has led to separation of the whiskers, which had an approximate length and diameter of 195 and 15 nm, respectively. The TEM images of the nanocomposites show similar dispersion of the whiskers in the PLA matrix, whether untreated or MA/DCP or DCP treated. It was found that the crystallization behavior of the PLA matrix changed somewhat depending on whether the samples were treated or not. The thermogravimetric analysis results show a slight decrease in the thermal stabilities of the untreated and the MA/DCP‐treated nanocomposite samples compared to that of the neat PLA, whereas the DCP treatment slightly improved the thermal stability of the nanocomposites. The storage modulus of the nanocomposites increased over the investigated temperature region, and the incorporation of sisal whiskers reduced the intensity of the glass transition at 67°C. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers
Structurally modified poly(vinyl alcohol) ionic composites as efficient humidity indicators
Authors: Mujahid Adnan , Afzal Adeel , Ahmad Mirza Nadeem , Farooq Muhammad Umar , Hussain Tajamal , Shehzad Khurram , Shah Asma Tufail
Published: May 2012

Synthesis of structurally modified poly(vinyl alcohol) (PVA) ionic composites is presented. Low‐molecular‐weight PVA (Mn = 18,000 g mol−1) is prepared and blended together with either copper or borate ions under ambient conditions to yield PVA–Cu and PVA–B ionic composites, respectively. The borate ions coalesce together with different polymeric chains of PVA, forming a 3D network structure, which is identified by the weakening of OH absorption in the infrared spectrum. On the other hand, copper ions yield a weakly crosslinked polyelectrolyte by forming a coordinated complex with the hydroxyl groups of PVA, which leads to an increase in the λmax value in the ultraviolet–visible spectrum. The surface morphology of these PVA‐based ionic composites is studied via atomic force microscopy. Furthermore, the quantitative estimation of copper in PVA–Cu composites is performed by atomic absorption spectroscopy. Among these PVA ionic composites, the PVA–Cu exhibits excellent moisture absorption capability and dramatic changes in the color of thin composite film, when exposed to 75% humidity atmosphere. The absolute recovery, recyclability, and stability of the PVA–Cu ionic composites not only enable them to be good humidity indicators but the results show that these composites can be employed as efficient humidity‐sensitive material on suitable transducers for environmental and industrial applications. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers
An Improved CTAB–Ammonium Acetate Method for Total RNA Isolation from Cotton
Authors: Zhao Lu , Ding Qi , Zeng Jun , Wang Fu‐Rong , Zhang Jun , Fan Shou‐Jin , He Xin‐Qiang
Published: May 2012

Introduction

Cotton is an important economic crop. Genetic, developmental and molecular studies of cotton require high‐quality total RNA from different tissues. Due to the richness in polyphenols and polysaccharides, the Trizol‐based methods and other commercial kits are unsuitable for RNA isolation from cotton. Available methods are generally laborious and time‐consuming.

Objective

To develop an easy, simple and rapid cetyltrimethylammonium bromide (CTAB)–ammonium acetate protocol that takes less time and obtains high yield and quality of RNA from polysaccharide‐ and polyphenol‐rich cotton tissues.

Methodology

Based on the original CTAB protocol, we used phenol–chloroform and chloroform–isoamyl alcohol to remove proteins, polysaccharides and polyphenols, and ammonium acetate to precipitate RNA, reducing the incubation time prior to RNA precipitation. After adding ammonium acetate to precipitate RNA, all centrifugation steps (14000 × g) were carried out at 4°C to avoid degradation.

Results

The procedure took only 1.5 h and was suitable for different cotton tissues. The A260:A280 ratios ranged from 1.80 to 1.85 with clear 28 s and 18 s ribosomal RNA bands in 1.2% agarose gel. The isolated RNA was usable for downstream molecular studies, such as reverse transcription polymerase chain reaction (PCR) and real‐time quantitative PCR.

Conclusion

The CTAB–ammonium acetate method is easy, rapid, low‐cost and effective for high‐quality RNA isolation from polysaccharide‐ and polyphenol‐rich cotton tissues. Copyright © 2012 John Wiley & Sons, Ltd.
Prenatal diagnosis of HbE‐Lepore and Hb Lepore‐β‐thalassemia: the importance of accurate genotyping of the couple at risk
Authors: Italia Khushnooma , Sheth Jayesh , Sawant Pratibha , Nadkarni Anita , Ghosh Kanjaksha , Colah Roshan
Published: May 2012

Objective

To accurately define unusual genotypes in compound heterozygotes for hemoglobinopathies before undergoing prenatal diagnosis.

Methods

The HPLC results showed one of the parents in case A and B and a child in case C to be HbE‐beta‐thalassemia. However, this finding did not correlate with molecular findings. Further screening of their grandparents and analysis of DNA for HbLepore were performed.

Results

The presence of a typical hump in the peak in the HbA2 window (10–15%) in one of the grandparents led to the suspicion of a large deletion. Further molecular screening for HbLepore concluded that case A was compound heterozygous for HbLepore‐Hollandia‐(δ22/β50) and HbE, case B for HbLepore‐Boston‐Washington‐(δ287/β116) and IVS‐I‐5(G > C) and case C for HbLepore‐Hollandia‐(δ22/β50) and HbE. The fetuses were found to be HbE trait in case A and HbLepore trait in case B and C.

Conclusion

Accurate genotyping of the couple at risk referred for prenatal diagnosis is important to identify uncommon genotypic combinations in compound heterozygous cases. Extended family studies are often useful to avoid misdiagnosis of the fetus. © 2012 John Wiley & Sons, Ltd.
Attitudes toward non‐invasive prenatal diagnosis among pregnant women and health professionals in Japan
Authors: Yotsumoto Junko , Sekizawa Akihiko , Koide Keiko , Purwosunu Yuditiya , Ichizuka Kiyotake , Matsuoka Ryu , Kawame Hiroshi , Okai Takashi
Published: May 2012

Objective

This study aims to assess the attitudes toward non‐invasive prenatal diagnosis (NIPD) and NIPD problems in clinical practice in Japan.

Methods

A mail‐in survey using a self‐reported questionnaire was conducted among pregnant women and health professionals. The questionnaire enquired about attitudes, concerns, and expectations regarding NIPD.

Results

The responses from 252 respondents revealed that pregnant women have more positive attitudes toward NIPD than health professionals. In addition, there were wide discrepancies in concerns and expectations about NIPD, between medical professionals and pregnant women. The respondents with less NIPD knowledge had a more positive attitude toward the clinical application of NIPD. There was concern expressed by clinical geneticists whether an NIPD test should be performed or not when there is a lack of knowledge about the NIPD. All of the health professionals emphasized the importance of providing genetic counseling prior to and after the testing.

Conclusion

Pregnant women place importance on the safety and non‐invasiveness of the NIPD tests, whereas medical professionals consider the diagnostic accuracy and reliability of the test to be the most important. Health professionals pointed out that the tests might be frequently performed without the pregnant women having adequate knowledge or counseling. © 2012 John Wiley & Sons, Ltd.
Evaluation of total hip arthroplasty devices using a total joint replacement registry
Authors: Paxton Elizabeth W. , Ake Christopher F. , Inacio Maria C.S. , Khatod Monti , Marinac‐Dabic Danica , Sedrakyan Art
Published: May 2012

Purpose

The purpose of this paper is to describe the infrastructure of the total joint replacement registry of a large integrated healthcare system's and emphasize challenges associated with orthopedic device classification and evaluation.

Methods

Using a large integrated healthcare system innovative infrastructure including electronic health record data, administrative data sources, and registry data collection, we evaluated device choice and outcomes of total hip arthroplasty (THA). Devices were classified into type of bearing surface (alternative versus traditional). Multiple imputation was used to accommodate missing data, and a logistic regression model was applied to assess the impact of patient and surgeon factors on choice of bearing surface. A Cox regression model was used to evaluate risk of aseptic revision while controlling for surgeon, site, and patient characteristics. Adjusted cumulative probability‐of‐event curves were created, comparing survival of alternative against traditional bearings of devices, with aseptic revision as the outcome of interest.

Results

The study sample consisted of 25 377 primary THAs with an average follow‐up of 2.7 years. Choice of bearing surface varied by surgeon and patient characteristics. After adjusting for patient, surgeon, and hospital covariates, results showed that the risk of aseptic revision associated with alternative bearings did not differ significantly from traditional bearing surfaces (hazard ratio = 1.33; 95% confidence interval: 0.90, 1.98).

Conclusions

Clinically rich data from a registry with linkages to electronic health records and other administrative databases improve identification of exposures, outcomes, and patient subgroups in medical device evaluation. These various data sources facilitate refined adjustment for potential confounders such as hospital, surgeon, and patient factors and ensure comprehensive device performance evaluation within registries. Copyright © 2012 John Wiley & Sons, Ltd.
Role of disease risk scores in comparative effectiveness research with emerging therapies
Authors: Glynn Robert J. , Gagne Joshua J. , Schneeweiss Sebastian
Published: May 2012

Background

Usefulness of propensity scores and regression models to balance potential confounders at treatment initiation may be limited for newly introduced therapies with evolving use patterns.

Objectives

To consider settings in which the disease risk score has theoretical advantages as a balancing score in comparative effectiveness research because of stability of disease risk and the availability of ample historical data on outcomes in people treated before introduction of the new therapy.

Methods

We review the indications for and balancing properties of disease risk scores in the setting of evolving therapies and discuss alternative approaches for estimation. We illustrate development of a disease risk score in the context of the introduction of atorvastatin and the use of high‐dose statin therapy beginning in 1997, based on data from 5668 older survivors of myocardial infarction who filled a statin prescription within 30 days after discharge from 1995 until 2004. Theoretical considerations suggested development of a disease risk score among nonusers of atorvastatin and high‐dose statins during the period 1995–1997.

Results

Observed risk of events increased from 11% to 35% across quintiles of the disease risk score, which had a C‐statistic of 0.71. The score allowed control of many potential confounders even during early follow‐up with few study endpoints.

Conclusions

Balancing on a disease risk score offers an attractive alternative to a propensity score in some settings such as newly marketed drugs and provides an important axis for evaluation of potential effect modification. Joint consideration of propensity and disease risk scores may be valuable. Copyright © 2012 John Wiley & Sons, Ltd.
Identification of metastatic cancer in claims data
Authors: Nordstrom Beth L. , Whyte Joanna L. , Stolar Marilyn , Mercaldi Catherine , Kallich Joel D.
Published: May 2012

Purpose

To develop algorithms to identify metastatic cancer in claims data, using tumor stage from an oncology electronic medical record (EMR) data warehouse as the gold standard.

Methods

Data from an outpatient oncology EMR database were linked to medical and pharmacy claims data. Patients diagnosed with breast, lung, colorectal, or prostate cancer with a stage recorded in the EMR between 2004 and 2010 and with medical claims available were eligible for the study. Separate algorithms were developed for each tumor type using variables from the claims, including diagnoses, procedures, drugs, and oncologist visits. Candidate variables were reviewed by two oncologists. For each tumor type, the selected variables were entered into a classification and regression tree model to determine the algorithm with the best combination of positive predictive value (PPV), sensitivity, and specificity.

Results

A total of 1385 breast cancer, 1036 lung, 727 colorectal, and 267 prostate cancer patients qualified for the analysis. The algorithms varied by tumor type but typically included International Classification of Diseases‐Ninth Revision codes for secondary neoplasms and use of chemotherapy and other agents typically given for metastatic disease. The final models had PPV ranging from 0.75 to 0.86, specificity 0.75–0.97, and sensitivity 0.60–0.81.

Conclusions

While most of these algorithms for metastatic cancer had good specificity and acceptable PPV, a tradeoff with sensitivity prevented any model from having good predictive ability on all measures. Results suggest that accurate ascertainment of metastatic status may require access to medical records or other confirmatory data sources. Copyright © 2012 John Wiley & Sons, Ltd.
Analyzing partially missing confounder information in comparative effectiveness and safety research of therapeutics
Authors: Toh Sengwee , García Rodríguez Luis A. , Hernán Miguel A.
Published: May 2012

Purpose

Electronic healthcare databases are commonly used in comparative effectiveness and safety research of therapeutics. Many databases now include additional confounder information in a subset of the study population through data linkage or data collection. We described and compared existing methods for analyzing such datasets.

Methods

Using data from The Health Improvement Network and the relation between non‐steroidal anti‐inflammatory drugs and upper gastrointestinal bleeding as an example, we employed several methods to handle partially missing confounder information.

Results

The crude odds ratio (OR) of upper gastrointestinal bleeding was 1.50 (95% confidence interval: 0.98, 2.28) among selective cyclo‐oxygenase‐2 inhibitor initiators (n = 43 569) compared with traditional non‐steroidal anti‐inflammatory drug initiators (n = 411 616). The OR dropped to 0.81 (0.52, 1.27) upon adjustment for confounders recorded for all patients. When further considering three additional variables missing in 22% of the study population (smoking, alcohol consumption, body mass index), the OR was between 0.80 and 0.83 for the missing‐category approach, the missing‐indicator approach, single imputation by the most common category, multiple imputation by chained equations, and propensity score calibration. The OR was 0.65 (0.39, 1.09) and 0.67 (0.38, 1.16) for the unweighted and the inverse probability weighted complete‐case analysis, respectively.

Conclusions

Existing methods for handling partially missing confounder data require different assumptions and may produce different results. The unweighted complete‐case analysis, the missing‐category/indicator approach, and single imputation require often unrealistic assumptions and should be avoided. In this study, differences across methods were not substantial, likely due to relatively low proportion of missingness and weak confounding effect by the three additional variables upon adjustment for other variables. Copyright © 2012 John Wiley & Sons, Ltd.
Performance of propensity score methods when comparison groups originate from different data sources
Authors: Hammill Bradley G. , Curtis Lesley H. , Setoguchi Soko
Published: May 2012

Purpose

To examine the performance of propensity score‐based methods for estimating relative risks when exposed and comparison subjects are selected from different data sources.

Methods

We conducted Monte Carlo simulations to assess the performance of propensity score methods under various scenarios in which exposed and comparison subjects were selected from different data sources for a comparative effectiveness study of a medical device.

Results

The use of propensity score methods in our simulated data scenarios often yielded estimates of relative risk that were close to the true effect, unless the comparison group differed from the exposed group systematically on a factor associated with the outcome. This situation caused severe bias regardless of which method was used but could be overcome if the exposed group could be restricted similarly to the comparison group. Mean square error of relative risk estimates was lowest for similarly restricted study groups and when the comparison group could be considered a random sample of the source population that generated the exposed group.

Conclusions

When exposed and comparison groups originated from different data sources, all propensity score methods yielded relatively unbiased and consistent estimates of relative risk in most situations reflected in our simulation study. Copyright © 2012 John Wiley & Sons, Ltd.
Simulation study of instrumental variable approaches with an application to a study of the antidiabetic effect of bezafibrate
Authors: Cai Bing , Hennessy Sean , Flory James H. , Sha Daohang , Ten Have Thomas R. , Small Dylan S.
Published: May 2012

Purpose

We studied the application of the generalized structural mean model (GSMM) of instrumental variable (IV) methods in estimating treatment odds ratios (ORs) for binary outcomes in pharmacoepidemiologic studies and evaluated the bias of GSMM compared to other IV methods.

Methods

Because of the bias of standard IV methods, including two‐stage predictor substitution (2SPS) and two‐stage residual inclusion (2SRI) with binary outcomes, we implemented another IV approach based on the GSMM of Vansteelandt and Goetghebeur. We performed simulations under the principal stratification setting and evaluated whether GSMM provides approximately unbiased estimates of the causal OR and compared its bias and mean squared error to that of 2SPS and 2SRI. We then applied different IV methods to a study comparing bezafibrate versus other fibrates on the risk of diabetes.

Results

Our simulations showed that unlike the standard logistic, 2SPS, and 2SRI procedures, our implementation of GSMM provides an approximately unbiased estimate of the causal OR even under unmeasured confounding. However, for the effect of bezafibrate versus other fibrates on the risk of diabetes, the GSMM and two‐stage approaches yielded similarly attenuated and statistically non‐significant OR estimates. The attenuation of the OR by the two‐stage and GSMM IV approaches suggests unmeasured confounding, although violations of the IV assumptions or differences in the parameters estimated could be playing a role.

Conclusion

The GSMM IV approach provides approximately unbiased adjustment for unmeasured confounding on binary outcomes when a valid IV is available. Copyright © 2012 John Wiley & Sons, Ltd.
One‐to‐many propensity score matching in cohort studies
Authors: Rassen Jeremy A. , Shelat Abhi A. , Myers Jessica , Glynn Robert J. , Rothman Kenneth J. , Schneeweiss Sebastian
Published: May 2012

Background

Among the large number of cohort studies that employ propensity score matching, most match patients 1:1. Increasing the matching ratio is thought to improve precision but may come with a trade‐off with respect to bias.

Objective

To evaluate several methods of propensity score matching in cohort studies through simulation and empirical analyses.

Methods

We simulated cohorts of 20 000 patients with exposure prevalence of 10%–50%. We simulated five dichotomous and five continuous confounders. We estimated propensity scores and matched using digit‐based greedy (“greedy”), pairwise nearest neighbor within a caliper (“nearest neighbor”), and a nearest neighbor approach that sought to balance the scores of the comparison patient above and below that of the treated patient (“balanced nearest neighbor”). We matched at both fixed and variable matching ratios and also evaluated sequential and parallel schemes for the order of formation of 1:n match groups. We then applied this same approach to two cohorts of patients drawn from administrative claims data.

Results

Increasing the match ratio beyond 1:1 generally resulted in somewhat higher bias. It also resulted in lower variance with variable ratio matching but higher variance with fixed. The parallel approach generally resulted in higher mean squared error but lower bias than the sequential approach. Variable ratio, parallel, balanced nearest neighbor matching generally yielded the lowest bias and mean squared error.

Conclusions

1:n matching can be used to increase precision in cohort studies. We recommend a variable ratio, parallel, balanced 1:n, nearest neighbor approach that increases precision over 1:1 matching at a small cost in bias. Copyright © 2012 John Wiley & Sons, Ltd.
Theoretical study of keto–enol tautomerism by quantum mechanical calculations (the QM/MC/FEP method)
Authors: Kaweetirawatt Thanayuth , Yamaguchi Toru , Higashiyama Tsutomu , Sumimoto Michinori , Hori Kenji
Published: May 2012

In this study, the tautomeric equilibrium between the keto and enol forms has been studied for five typical ketones and aldehydes: i‐butanal, acetaldehyde, acetone, acetylacetone, and dimedone. The level of theory used in the gas‐phase calculation was Becke, three‐parameter, Lee–Yang–Parr/6‐311G(d,p)//Becke, three‐parameter, Lee–Yang–Parr/6‐31G(d). The free energies of solvation were included in the calculation by using the free‐energy perturbation method based on Monte Carlo simulation, that is, the quantum mechanical/Monte Carlo/free‐energy perturbation method. Three different models, incorporating no‐water, one‐water, and two‐waters, were adopted. The results showed that in the gas phase the addition of water molecules to the reaction mechanism caused the activation barriers (ΔG‡gas) to decrease by half relative to the water‐free mechanism, but there was no effect on the relative difference in free energy, ΔGgas. The solvation effects (ΔGsol), based on quantum mechanical/Monte Carlo/free‐energy perturbation calculations, were added to those of the gas‐phase results of the one‐water and two‐waters models. The two‐waters model produced values that were very consistent with the experimental data for all of the tautomers. The differences in the relative Gibbs free energy (ΔGrxn) were less than 1.0 kcal mol–1. In summary, the inclusion of solvent molecules in gas‐phase calculations plays a very important role in producing results consistent with experimental data. Copyright © 2012 John Wiley & Sons, Ltd.
Acidities of strong neutral Brønsted acids in different media
Authors: Raamat Elin , Kaupmees Karl , Ovsjannikov Gea , Trummal Aleksander , Kütt Agnes , Saame Jaan , Koppel Ivar , Kaljurand Ivari , Lipping Lauri , Rodima Toomas , Pihl Viljar , Koppel Ilmar A. , Leito Ivo
Published: May 2012

Acidities of different families of acids are examined in media of different physical and chemical nature: water, acetonitrile (AN), 1,2‐dichloroethane (DCE) and the gas phase, with special emphasis on strong acids. Included are OH (carboxylic acids, alcohols, and phenols), NH (sulfonamides, imides), and CH (phenylmalononitriles, etc.) acids as well as HCl, HBr, and HI. Dependence of the acidity trends on moving from water to the gas phase on the nature of the acidity center, and the molecular structure are analyzed. The acidity orders are different in water, AN, DCE, and the gas phase. In some cases the differences are dramatic. AN and DCE display similar acidity order in the set of the investigated acids. It is demonstrated that the decisive factor for the behavior of the acids when transferring between different media is the extent of charge delocalization in the anion and that the recently introduced weighted average positive sigma parameter in spite of its simplicity enables interpretation of the trends in the majority of cases. Copyright © 2012 John Wiley & Sons, Ltd.
Active Layer Characteristics At Ten Borehole Sites In Alpine Permafrost Terrain, Switzerland
Authors: Zenklusen Mutter Evelyn , Phillips Marcia
Published: May 2012

This study investigates and compares active layer characteristics determined from ground temperature measurements at ten borehole sites in various types of Alpine permafrost terrain. Active layer thickness (ALT) remained fairly constant at the individual boreholes over the past five to 14 years, but was highly variable among the sites due to local terrain characteristics. To allow intra‐site comparisons, a characteristic depth within the active layer was determined for each site. The temperature series either measured or interpolated for that depth were used to investigate different thermal stages during the annual thawing and refreezing cycle. The relation between air temperature thawing‐degree days and ALT was investigated on an annual, seasonal and daily basis. The results show that at least daily data are required to establish the relevant characteristics of active layer development. Periods of slow advance of the thaw plane, interpreted as being due to the presence of ice‐bearing layers within the active layer, are particularly important to the final ALT. Rapid active layer deepening, however, can occur due to the formation of taliks caused by lateral thermal disturbances below the active layer. Copyright © 2012 John Wiley & Sons, Ltd.