bluuebunny/crossref_metadata_2025_split huggingface dataset:
An Evaluation of Methods for the Estimation of Sensitivity and Specificity of Site‐Specific Diagnostic Tests
Authors: Ahn Chul 
Published: May 2007

AbstractThe performance of diagnostic tests is often evaluated by estimating their sensitivity and specificity with respect to a traditionally accepted standard test regarded as a “gold standard” in making the diagnosis. Correlated samples of binary data arise in many fields of application. The fundamental unit for analysis is occasionally the site rather than the subject in site‐specific studies. Statistical methods that take into account the within‐subject corelation should be employed to estimate the sensitivity and the specificity of diagnostic tests since site‐specific results within a subject can be highly correlated. I introduce several statistical methods for the estimation of the sensitivity and the specificity of sitespecific diagnostic tests. I apply these techniques to the data from a study involving an enzymatic diagnostic test to motivate and illustrate the estimation of the sensitivity and the specificity of periodontal diagnostic tests. I present results from a simulation study for the estimation of diagnostic sensitivity when the data are correlated within subjects. Through a simulation study, I compare the performance of the binomial estimator pCBE, the ratio estimator pCBE, the weighted estimator pCWE, the intracluster correlation estimator pCIC, and the generalized estimating equation (GEE) estimator PCGEE in terms of biases, observed variances, mean squared errors (MSE), relative efficiencies of their variances and 95 per cent coverage proportions. I recommend using PCBE when σ == 0. I recommend use of the weighted estimator PCWE when σ = 0.6. When σ == 0.2 or σ == 0.4, and the number of subjects is at least 30, PCGEE performs well.
Testing for Absence of Qualitative Interactions Between Risk Factors and Treatment Effects
Authors: Wellek S. 
Published: May 2007

AbstractThe problem of investigating qualitative interactions (QI's) between subsets of patients defined by means of some risk factors, and treatment effects in clinical trials is considered from a viewpoint which leads to interchanging the hypotheses of the testing problem dealed with in the existing literature on QI's. A natural way of approaching this reverse problem is to apply one of the tests available for the original problem of detecting QI's at level 1 — α and to reject the null hypothesis of the new problem if and only if this test accepts. Unfortunately, this would require unbiasedness of the level 1 — α test for existence of QI's to start with, a property which exhibits neither the likelihood ratio procedure derived in the seminal paper of GAIL and SIMON (1985), nor the test based on the extreme order statistics which was introduced by several authors in 1993. Nevertheless we show that there is a valid test for absence of QI's which depends on the extreme values only and coincides with the maximum likelihood ratio procedure for the same problem. Furthermore, the procedure is generalized to the problem of testing for absence of relevant QI's, i.e. of qualitative interactions exceeding some specified tolerance ε > 0.
Confidence Regions for Spectral Peak Frequencies
Authors: Timmer Jens , Lauk M. , Lücking C. H. 
Published: May 2007

AbstractA procedure is proposed to obtain confidence regions for spectral peak frequencies. The method is based on resampling the periodogram from the estimated spectrum in order to reestimate the spectrum and its peak frequency. We investigate the dependence of the results from the applied spectral estimator in three simulation studies and apply the method to tremor data.
Parametric Methods for Bivariate Quantile‐Partitioned Tables and the Efficiency of Corresponding Nonparametric Methods
Authors: Borkowf Craig B. , Gail Mitchell H. 
Published: May 2007

AbstractIn order to study the agreement between two continuous measurements on a sample of individuals, epidemiologists sometimes partition the original bivariate data into categories defined by the empirical quantiles of the two marginal distributions. The counts in the resulting two‐way contingency table have the empirical bivariate quantile‐partitioned (EBQP) distribution rather than the conventional multinomial distribution. BORKOWF et al. (1997) developed the asymptotic theory and inferential procedures for estimates of measures of agreement calculated from EBQP tables. In this paper, we develop parametric methods for bivariate quantile‐partitioned (BQP) tables. We use these methods to study the efficiency of nonparametric (EBQP) methods and to improve the precision of estimates of measures of agreement. We present computational methods for estimating certain measures of agreement (kappa, weighted kappa, and row proportions) together with their variances. Numerical studies and an example show that nonparametric (EBQP) estimates of kappa and certain row proportions tend to be quite inefficient compared to parametric estimates, whereas nonparametric estimates of weighted kappa can be relatively more efficient for some underlying distributions. Thus, investigators should weigh the efficiency advantages of parametric estimates against possible biases that can result from choosing an inappropriate parametric model when they employ BQP tables to study agreement.
On Conditions for Validity of the Approximations to Fisher's Exact Test
Authors: Martínandrés A. , Tejedor I. Herranz 
Published: May 2007

AbstractA 2 × 2 table is analyzed from the conditional viewpoint, using Fisher's exact test, for which there is abundant software nowadays (StatXact, SPSS with the module “Exact Test”, …). Nevertheless, because it is well‐nigh impossible to work the test out “by hand”, it is customary in many books to analyze the table, in an approximate fashion, by using the classic chi‐square test with the appropriate continuity correction, and this is what many researchers do in practice. Unfortunately little research has been carried out on the validity conditions of the test (remember the classic advice that the minimum expected quantity E should be larger than or equal to 5), so that it is applied indiscriminately with the obvious danger of obtaining erroneous results. In this paper the exact validity conditions (which depend not only on E, but also on the real P‐value, on the size of the sample, on the number of tails of the test and on the continuity correction used) are determined, showing that the classic condition E > 5 can be either very strict or quite liberal (depending on the circumstances) and it can even be necessary for the test to have E > 20. A similar study is made of the case of using the binomial approximation, while the Poisson approximation is also discussed.The article ends with a list of rules and precautions to be borne in mind by researchers using the approximate methods. The strict rules are complex enough to make the researcher want to use the exact test, but simplified (and conservative) rules are also given for those unable to do so.
Bioluminescence imaging for assessment and normalization in transfected cell arrays
Authors: Pannier Angela K. , Ariazi Eric A. , Bellis Abigail D. , Bengali Zain , Jordan V. Craig , Shea Lonnie D. 
Published: May 2007

AbstractTransfected cell arrays (TCAs) represent a high‐throughput technique to correlate gene expression with functional cell responses. Despite advances in TCAs, improvements are needed for the widespread application of this technology. We have developed a TCA that combines a two‐plasmid system and dual‐bioluminescence imaging to quantitatively normalize for variability in transfection and increase sensitivity. The two‐plasmids consist of: (i) normalization plasmid present within each spot, and (ii) functional plasmid that varies between spots, responsible for the functional endpoint of the array. Bioluminescence imaging of dual‐luciferase reporters (renilla, firefly luciferase) provides sensitive and quantitative detection of cellular response, with minimal post‐transfection processing. The array was applied to quantify estrogen receptor α (ERα) activity in MCF‐7 breast cancer cells. A plasmid containing an ERα‐regulated promoter directing firefly luciferase expression was mixed with a normalization plasmid, complexed with cationic lipids and deposited into an array. ER induction mimicked results obtained through traditional assays methods, with estrogen inducing luciferase expression 10‐fold over the antiestrogen fulvestrant or vehicle. Furthermore, the array captured a dose response to estrogen, demonstrating the sensitivity of bioluminescence quantification. This system provides a tool for basic science research, with potential application for the development of patient specific therapies. Biotechnol. Bioeng. 2007;98; 486–497. © 2007 Wiley Periodicals, Inc.
Separation and determination of isoflavones in red clover by micellar electrokinetic capillary chromatography
Authors: Zhang Yu , Chen Juan , Zhao Liang , Shi Yan‐Ping 
Published: May 2007

AbstractA micellar electrokinetic capillary chromatography (MECC) method has been developed for the determination of the four isoflavones, i.e. biochanin A, formononetin, genstein and daidzein in red clover (Trifolium Pratense L.). The effect of running buffer pH and concentration were investigated. An electrolyte composed of 30 mm borate, 20 mm sodium dodecyl sulfate (SDS) and 4 mg/mL HP‐β‐CD containing 5% (v/v) ethanol at pH 10.1 provides a satisfactory separation for all the analytes. The applied voltage was 25 kV, and the capillary temperature was kept constant at 25°C with a UV detection at 254 nm. The relative standard deviations (RSD) of the migration time and peak area were less than 1.73 and 3.94% (intra‐day), and 2.29 and 4.38% (inter‐day), respectively, under the optimized separation conditions. Regression equations revealed a good linear relationship between the peak area of each compound and its concentration. The contents of the four compounds in red clover were successfully determined with satisfactory repeatability and recovery. Copyright © 2007 John Wiley & Sons, Ltd.
Can defendants with mental retardation successfully fake their performance on a test of competence to stand trial?
Authors: Everington Caroline , Notario‐Smull Heidi , Horton Mel L. 
Published: May 2007

AbstractThe purpose of this study was to determine whether criminal defendants with mental retardation can feign poor performance on a test of competence to stand trial. Four groups of adjudicated criminal defendants were given a test of competence to stand trial. In the experimental condition, defendants with mental retardation (MR) and mentally typical defendants (non‐MR) were given instructions to fake their performance on the test. In the control, MR defendants and non‐MR defendants took the test under standard conditions. The results indicated that both the MR and non‐MR fakers scored significantly lower than the MR and non‐MR controls. There was no significant difference in the scores of the MR and non‐MR fakers. The results suggest that defendants with mental retardation may be able to successfully fake their performance in certain circumstances. Implications of these findings are discussed. Copyright © 2007 John Wiley & Sons, Ltd.
The function of punishment in the “civil” commitment of sexually violent predators
Authors: Carlsmith Kevin M. , Monahan John , Evans Alison 
Published: May 2007

AbstractTwo experiments find that support for civil commitment procedures for sexually violent predators is based primarily upon the retributive rather than incapacitative goals of respondents. Two discrete samples composed of students (N = 175) and jury‐eligible citizens (N = 200) completed experimental surveys assessing their support or opposition to scenarios in which a sexual predator was to be released after completing his criminal sentence. Respondents were sensitive to likelihood of recidivism only when the initial sentence was sufficiently punitive. When initial sentence was lenient, respondents strongly supported civil commitment without regard to future risk. Results are discussed in light of the U.S. Supreme Court's ruling inKansas v. Hendricks(1997) on the constitutionality of civil commitment laws for sexually violent predators. Copyright © 2007 John Wiley & Sons, Ltd.
Newer concepts for imaging anomalous aortic origin of the coronary arteries in adults
Authors: Angelini Paolo , Flamm Scott D. 
Published: May 2007

AbstractOf the different kinds of coronary anomalies observed in adults, anomalous origin of a coronary artery from the opposite sinus of Valsalva with an “interarterial” course (ACAOS) entails a high risk of clinical consequences related to the intramural course of the ectopic coronary artery. We review current imaging modalities for differentiating this condition from generally benign coronary anomalies and for quantifying the severity of individual cases. For identifying ACAOS, noninvasive modalities (echocardiography, computed tomographic angiography, and coronary magnetic resonance angiography) are preferred: the favored modalities are transthoracic echocardiography in children and multidetector computed tomography in adults. For evaluating the pathophysiologic mechanisms of ischemia in ACAOS and subclassifying the severity of individual forms, coronary intravascular ultrasonography provides enhanced temporal and spatial resolution. The critical quantifiable features of the coronary anatomy in ACAOS seem to be hypoplasia, lateral compression at the level of the intramural course, and possibly exercise‐related further narrowing of the proximal ectopic segment. Definitive guidelines are being developed for the optimal workup and treatment of ACAOS. © 2007 Wiley‐Liss, Inc.
Highly Stereoselective Peptide Modifications through Pd‐Catalyzed Allylic Alkylations of Chelated Peptide Enolates
Authors: Deska Jan , Kazmaier Uli 
Published: May 2007

AbstractDeprotonation of peptides in the presence of zinc chloride gives rise to highly reactive nucleophiles that can be subjected to palladium‐catalyzed allylic alkylation reactions. Excellent diastereoselectivities are obtained that are nearly independent of the allylic substrate used. By using this protocol, highly functionalized side chains can also be incorporated in excellent yields and selectivities. The stereochemical outcome of the reaction is exclusively controlled by the peptide chain as long as terminal π‐allyl–palladium complexes are involved. Probably, there is a threefold coordination, at least, of the deprotonated peptide chain to the chelating zinc ion. In such metal peptide complexes, one face of the generated enolate is shielded by the side chain of the adjacent amino acid, thus directing the electrophilic attack onto the opposite face. This behavior explains why an S amino acid always generates an R amino acid (and the other way round).
The genetics and embryology of zebrafish metamerism
Authors: Holley Scott A. 
Published: May 2007

AbstractSomites are the most obvious metameric structures in the vertebrate embryo. They are mesodermal segments that form in bilateral pairs flanking the notochord and are created sequentially in an anterior to posterior sequence concomitant with the posterior growth of the trunk and tail. Zebrafish somitogenesis is regulated by a clock that causes cells in the presomitic mesoderm (PSM) to undergo cyclical activation and repression of several notch pathway genes. Coordinated oscillation among neighboring cells manifests as stripes of gene expression that pass through the cells of the PSM in a posterior to anterior direction. As axial growth continually adds new cells to the posterior tail bud, cells of the PSM become relatively less posterior. This gradual assumption of a more anterior position occurs over developmental time and constitutes part of a maturation process that governs morphological segmentation in conjunction with the clock. Segment morphogenesis involves a mesenchymal to epithelial transition as prospective border cells at the anterior end of the mesenchymal PSM adopt a polarized, columnar morphology and surround a mesenchymal core of cells. The segmental pattern influences the development of the somite derivatives such as the myotome, and the myotome reciprocates to affect the formation of segment boundaries. While somites appear to be serially homologous, there may be variation in the segmentation mechanism along the body axis. Moreover, whereas the genetic architecture of the zebrafish, mouse, and chick segmentation clocks shares many common elements, there is evidence that the gene networks have undergone independent modification during evolution. Developmental Dynamics 236:1422–1449, 2007. © 2007 Wiley‐Liss, Inc.
Wide‐bore monolithic column for electrochromatography
Authors: Yuan Ruijuan , Ding Guosheng , Guo Yugao , Liu Danning , Bao James J. 
Published: May 2007

AbstractA new wide‐bore electrophoresis (WE) system adopting an inner cooling device was set up to perform electrochromatography. In this system, a quartz tube of 1.2 mm inner diameter was used as the separation channel. The Joule heat generated during electrophoresis was removed timely through the outer surface of the quartz tube and a cooling capillary inserted into the quartz tube. A proper coolant passed through the cooling capillary to further improve the cooling efficiency. In the primary research, a polyacrylamide monolithic column was successfully prepared in this quartz tube. Then it was evaluated in the electrochromatographic mode. An electric field strength as high as 625 V/cm can be applied to this system without obvious deviation of the current from the linear curve of the Ohm plot. Sample volume as high as 1 μL was injected into the WE system and reasonable efficiency was obtained for separation of the test compounds.
Rapid determination of genomic DNA length for new bacteriophages
Authors: Serwer Philip , Hayes Shirley J. , Thomas Julie A. , Griess Gary A. , Hardies Stephen C. 
Published: May 2007

AbstractdsDNA viruses with long genomes (>200 kb) are expected to be a major source of novel genes. To rapidly characterize the genomes of newly isolated dsDNA bacteriophages, we develop here a procedure for the PFGE of intact long DNA genomes from bacteriophage particles in unfractionated, infected cell lysates of either liquid or gelled cultures. The DNA used for PFGE is suitable for sequencing after extraction with phenol. The PFGE is tuned to the range of expected DNA lengths. This procedure bypasses the isolation of bacteriophage particles and is useful for PFGE analysis of DNA from dissected zones of bacteriophage plaques.
Determination of catecholamines by CE with direct chemiluminescence detection
Authors: Liu Yan‐Ming , Wang Cheng‐Quan , Mu Hai‐Bei , Cao Jun‐Tao , Zheng Yan‐Li 
Published: May 2007

AbstractA rapid and sensitive method to detect three catecholamines, isoprenaline, epinephrine, and dopamine, by CE coupled with direct luminol‐potassium periodate chemiluminescence (CL) detection is described. The conditions for CE separation and CL reaction were systematically optimized. Under the optimum conditions, the baseline separation of three catecholamines was achieved within 6.5 min. The LODs obtained in standard solution were 5.3 × 10–8 mol/L for isoprenaline, 4.7 × 10–8 mol/L for epinephrine, and 1.5 × 10–7 mol/L for dopamine. The RSD of the migration time and peak area were less than 1.8 and 3.6% (n = 5), respectively. The present method was applied to the determination of the dopamine in urine samples of cigarette smokers and nonsmokers. The results obtained indicate that there is a close relationship between the content of dopamine in human urine and the amount of cigarettes smoked daily; the level of dopamine in smokers is higher than in nonsmokers.
Analysis of substances to be used as internal standards in MEKC
Authors: Hasemann Phillip , ter Balk Marieke , Wätzig Hermann 
Published: May 2007

AbstractThe use of internal standards (ISs) improves the quantitative performance of CE. However, ISs chosen for use in CZE often cannot be used for micellar EKC (MEKC). Therefore 22 substances were investigated as potential ISs in MEKC. These substances were selected based upon a literature search. The substances were investigated using a method similar to the standard operating conditions for MEKC as recommended by S. Terabe. Furthermore, the migration time and the corrected migration time (kS) were determined for each substance to establish the migration position relative to other peaks in the electropherograms. A combination of eight substances, selected according to the obtained results (tm = 4 up to 12 min), was tested for practical benefit and applicability. The peak area precision was in the range of 0.8 and 1.2% (n = 60), and the peaks were well shaped for all the investigated substances. The selected substances covered a wide migration time window and therefore they can be regarded as suitable for future analysis at any required migration position.
Distribution of piperitone oxide stereoisomers in Mentha and Micromeria species and their chemical syntheses
Authors: Larkov Olga , Matasyoh Josphat C. , Dudai Nativ , Lewinsohn Efraim , Mayer Alfred A. , Ravid Uzi 
Published: May 2007

AbstractChiral GC–MS analyses of natural and synthetic trans‐ and cis‐piperitone oxide were performed on an Rt‐βDEX‐sm capillary column in order to clarify the stereochemistry of their enantiomeric forms. Only enantiomerically pure laevo‐rotatory piperitone oxides, (1S,2S,4S)‐trans‐piperitone oxide and (1S,2S,4R)‐cis‐piperitone oxide, were detected by chiral analyses of Micromeria fruticosa (L.) Druce and Mentha longifolia L. The occurrence of the cis‐ and trans‐piperitone oxides was dependent on the population of the species. In all cases (1S,2S,4S)‐trans‐piperitone oxide was detected together with (4S)‐piperitone, while (1S,2S,4R)‐cis‐piperitone oxide was detected together with (4R)‐piperitone in the plants analysed. The four stereoisomers of trans‐ and cis‐piperitone oxide were obtained by alkaline epoxidation of both (4R)‐ and (4S)‐piperitone. The formation of the 1,2‐epoxide can take place on either side of the 1,4‐substituted six‐membered ring. Racemization at C4 was observed under alkaline epoxidation reaction conditions due to keto‐enol tautomerism. Copyright © 2007 John Wiley & Sons, Ltd.
Expression and functional analysis of the cellular retinoic acid binding protein from silkworm pupae (Bombyx mori)
Authors: Wang Xue‐Jian , Chen Jian , Lv Zheng‐Bing , Nie Zuo‐Ming , Wang Dan , Shen Hong‐Dan , Wang Xue‐Dong , Wu Xiang‐Fu , Zhang Yao‐Zhou 
Published: May 2007

AbstractCellular retinoic acid binding protein (CRABP) is a member of intracellular lipid‐binding protein (iLBP), and closely associated with retinoic acid (RA) activity. We have cloned the CRABP gene from silkworm pupae and studied the interaction between Bombyx mori CRABP (BmCRABP) and all‐trans retinoic acid (atRA). The MTT assay data indicated that when BmCRABP is overexpressed in Bm5 cells, the cells dramatically resisted to atRA‐induced growth inhibition. Conversely, the cells were sensitive to atRA treatment upon knocking down the BmCRABP expression. Subcellular localization revealed that BmCRABP is a cytoplasm protein, even when treated with atRA, the CRABP still remained in the cytoplasm. These data demonstrated that the function of BmCRABP have an effect on the physiological function of atRA. J. Cell. Biochem. 102: 970–979, 2007. © 2007 Wiley‐Liss, Inc.