bluuebunny/crossref_metadata_2025 huggingface dataset:
Method of Determination of Emission Properties of Very Weakly Emitting Species Ensuring Elimination of Emission of Impurities
Authors: Ciesielska Barbara , Łukaszewicz Adam , Celewicz Lech , Maciejewski Andrzej , Kubicki Jacek
Published: January 2007

This paper describes a new type of spectrofluorimeter, composed of a high-performance liquid chromatography (HPLC) system directly connected to a fluorescence detector and an absorption photodiode array detector, designed for studying the emission of weakly emitting species. Procedures for measurements of emission spectra (ES), emission excitation spectra (EES), and quantum yields of emission (φE) for very weakly emitting systems (ΦE ≥ 10−7) have been proposed. The original methodical solution allows verification of whether the emission observed comes solely from the compound studied (and not from its impurities) or from some photochemical or thermal process taking place during measurements. Thanks to the use of this new type of spectrofluorimeter, it is possible to establish with a high probability that the dependence of the shape and position of the ES on the excitation wavelength and the differences between EES and absorptance spectra are due to photo-physical and/or photochemical properties of the compound studied and not due to the presence of emitting impurities. An especially interesting application of this method is to study the emission of species whose very weak emission is related to a very short lifetime as well as a low radiative rate constant. It is particularly suitable to the study of the emission properties of flexible molecules that can occur in a few conformers of different absorption and emission properties. The performance of the method is illustrated by the results of the emission studies carried out for Nα-acetyl-2-(uracil-5-yl)-L-tryptophan N-ethylamide.
Adhesive Secretions of Live Mussels Observed in Situ by Attenuated Total Reflection—Infrared Spectroscopy
Authors: Gao Zhihong , Bremer Phil J. , Barker Michael F. , Tan Eng Wui , McQuillan A. James
Published: January 2007

The chemical species involved in the adhesion of blue mussels ( Mytilus galloprovincialis) and greenshell mussels ( Perna canaliculus) to surfaces has been investigated using in situ attenuated total reflection infrared (ATR-IR) spectroscopy. Mussel spat ranging in size from 0.5 to 25 mm were placed in a flow cell containing a ZnSe multiple internal reflection prism and supplied with temperature-controlled seawater. Distinctively different absorption spectra were obtained when the mussels were predominantly moving across the surface or forming permanent bonds. With limited movement, the absorption spectrum was characteristic of protein with peaks near 1647 cm−1 (amide I), 1543 cm−1 (amide II), and 1235 cm−1 (amide III). When the mussels were observed to be moving across the surface of the ATR-IR crystal there was a strong broad absorption maximum around 1200–900 cm−1 (carbohydrate polymers), presumably due to the secretion of a weakly acidic mucopolysaccharide. Distinct differences in the spectra obtained from the adhesive secretions of blue or greenshell mussels were not observed. The data presented is the first reported use of IR spectroscopy to obtain in situ, real-time, chemical data on the interactions between invertebrates and substrates immersed in sea water.
Attenuated Total Reflection Fourier Transform Infrared Imaging with Variable Angles of Incidence: A Three-Dimensional Profiling of Heterogeneous Materials
Authors: Chan K. L. Andrew , Kazarian Sergei G.
Published: January 2007

Depth profiling in Fourier transform infrared (FT-IR) spectroscopic imaging has been demonstrated using a single reflection variable angle attenuated total reflection (ATR) accessory. Chemical information about samples can be obtained in three dimensions by acquiring ATR-FT-IR images at different angles of incidence through the ATR crystal. The image quality and field of view achieved at different angles of incidence has been discussed. A polymer film comprising two layers has been used as an example to demonstrate the principle of the measurement. The demonstrated approach is a promising tool to obtain depth profiles of heterogeneous materials. The extent of the measured depths is limited and ranges from approximately 0.3 to 4 μm, but the spatial resolution in the z-direction is not limited by diffraction. The development of this approach opens up the possibility to study the spatial heterogeneity of thin films including biological tissues, such as hair and skin, with high depth resolution.
Development of a Surface-Enhanced Raman Technique for Biomarker Studies on Mars
Authors: Dunn Darrell S. , Sridhar Narasi , Miller Michael A. , Price Kendra T. , Pabalan Roberto , Abrajano Teofilo A.
Published: January 2007

Raman spectroscopy has been identified as a potentially useful tool to collect evidence of past or present life on extraterrestrial bodies. However, it is limited by its inherently low signal strength. In this investigation, laboratory tests were conducted using surface-enhanced Raman spectroscopy (SERS) in an “inverted” mode to detect the presence of organic compounds that may be similar to possible biomarkers present on Mars. SERS was used to overcome the inherently low signal intensity of Raman spectroscopy and was an effective method for detecting small concentrations of organic compounds on a number of surfaces. For small organic molecules, dissolution of the molecule to be analyzed in a suitable solvent and depositing it on a prepared SERS substrate for analysis is possible. However, for larger molecules, an “inverted” SERS (iSERS) technique was shown to be effective. In iSERS, nanoparticles of silver or gold were deposited on the mineral substrate/organic compound to be analyzed. Benzotriazole, benzoic acid, and phthalic acid were used as test organic analogs and the iSERS technique was able to detect femtomole levels of the analytes. The interference from various mineral substrates was also examined. Different methods of depositing silver particles were evaluated, including ion beam-assisted vapor deposition and deposition from aqueous colloidal suspensions.
Raman Spectroscopic Investigation of Solid Samples Using a Low-Repetition-Rate Pulsed Nd:YAG Laser as the Excitation Source
Authors: Zhang Jing , Feng Zhaochi , Li Meijun , Chen Jun , Xu Qian , Lian Yuxiang , Li Can
Published: January 2007

We tried to investigate the possibility of using a low-repetition-rate pulsed Nd:YAG laser as an excitation source in Raman measurements for solid samples. Based on the results from the Raman spectra excited by continuous wave (CW) 532 and 325 nm lasers, we studied the influence of laser energy and irradiation time of 532 and 355 nm pulsed Nd:YAG lasers (10 Hz repetition rate) on the thermal stability of (NH4)6Mo7O24·4H2O, NH4VO3, and Ce(NO3)3·6H2O samples, which usually decompose at relatively low temperatures. It is observed that the heating temperature estimated at these samples caused by the irradiation of 532 nm pulsed laser with 22 mJ is no higher than 100 °C even for 60 min exposure. The 355 nm pulsed laser with energies below 8.0 mJ hardly causes thermal damage to hydrated (NH4)6Mo7O24 and hydrated Ce(NO3)3 samples. However, a 355 nm pulsed laser with only 2.2mJ causes heating temperatures as high as 200 °C in the NH4VO3 sample. These great differences should be attributed to the electronic absorbance of the above three samples at 355 nm. We also found that a 532 nm pulsed laser with even 22 mJ and a 355 nm pulsed laser with even 8.0 mJ do not cause the phase transition of TiO2 and ZrO2, whose phase transformation easily takes place at elevated temperatures, but pulsed lasers could remove some oxygen atoms from these samples. In addition, for L-alanine and DL-β-phenylalanine biological samples, it is surprisingly found that they are not damaged by the 355 nm pulsed laser even when the laser energy is increased to 8.0 mJ, possibly because they do not absorb the 355 nm laser. Based on these results, it is demonstrated that low-repetition-rate pulsed lasers with appropriate wavelength and energy can be employed as the excitation sources of Raman spectroscopy for characterizing some solid samples, even the thermally unstable samples.
Application of Sample—Sample Two-Dimensional Correlation Spectroscopy to Determine the Glass Transition Temperature of Poly(Ethylene Terephthalate) Thin Films
Authors: Hu Yun , Zhang Ying , Li Boyan , Ozaki Yukihiro
Published: January 2007

The glass transition temperatures ( Tg) of poly(ethylene terephthalate) (PET) thin films with different thicknesses are determined by analyzing their in situ reflection–absorption infrared (RAIR) spectra measured over a temperature range of 28 to 84 °C. The criterion of standard deviation of the covariance matrices is used as a graphical indicator for the determination of the Tg present in the sample–sample two-dimensional (2D) correlation spectra calculated from the temperature-dependent RAIR spectra. After two data pretreatments of the first derivative of the spectral absorbance versus temperature and the mean normalization over the wavenumbers are sequentially carried out on the RAIR spectra, an abrupt change of the first-derivative correlation spectra with respect to temperature is quickly obtained. It reflects the temperature at which the apparent intensity changes in pertinent absorption bands of PET thin films take place due to the dramatic segmental motion of PET chain conformation. The Tg of the thin PET films is accordingly determined. The results reveal that it decreases with a great dependence on the film thickness and that sample–sample 2D correlation spectroscopy enables one to determine the transition temperature of polymer thin films in an easy and valid way.
Practical Aspects of the Maximum Entropy Inversion of the Laplace Transform for the Quantitative Analysis of Multi-Exponential Data
Authors: Lórenz-Fonfría Víctor A. , Kandori Hideki
Published: January 2007

The number, position, area, and width of the bands in a lifetime distribution give the number of exponentials present in time-resolved data and their time constants, amplitudes, and heterogeneities. The maximum entropy inversion of the Laplace transform (MaxEnt-iLT) provides a lifetime distribution from time-resolved data, which is very helpful in the analysis of the relaxation of complex systems. In some applications both positive and negative values for the lifetime distribution amplitudes are physical, but most studies to date have focused on positive-constrained solutions. In this work, we first discuss optimal conditions to obtain a sign-unrestricted maximum entropy lifetime distribution, i.e., the selection of the entropy function and the regularization value. For the selection of the regularization value we compared four methods: the χ2 criterion and Bayesian inference (already used in sign-restricted MaxEnt-iLT), and the L-curve and the generalized cross-validation methods (not yet used in MaxEnt-iLT to our knowledge). Except for the frequently used χ2 criterion, these methods recommended similar regularization values, providing close to optimum solutions. However, even when an optimal entropy function and regularization value are used, a MaxEnt lifetime distribution will contain noise-induced errors, as well as systematic distortions induced by the entropy maximization (regularization-induced errors). We introduce the concept of the apparent resolution function in MaxEnt, which allows both the noise and regularization-induced errors to be estimated. We show the capability of this newly introduced concept in both synthetic and experimental time-resolved Fourier transform infrared (FT-IR) data from the bacteriorhodopsin photocycle.
Wavelength Selection for Multivariate Calibration Using Tikhonov Regularization
Authors: Stout Forrest , Kalivas John H. , Héberger Károly
Published: January 2007

Prediction of sample properties using spectroscopic data with multivariate calibration is often enhanced by wavelength selection. This paper reports on a built-in wavelength selection method in which the estimated regression vector contains zero to near-zero coefficients for undesirable wavelengths. The method is based on Tikhonov regularization with the model 1-norm (TR1) and is applied to simulated and near-infrared (NIR) spectral data. Models are also formed from wavelength subsets determined by the standard method of stepwise regression (SWR). Harmonious (bias/variance tradeoff) and parsimonious considerations are compared with and without wavelength selection for principal component regression (PCR), ridge regression (RR), partial least squares (PLS), and multiple linear regression (MLR). Results show that TR1 models generally contain large baseline regions of near-zero coefficients, thereby essentially achieving built-in wavelength selection. For example, wavelengths with spectral interferences and/or poor signal-to-noise ratios obtain near zero regression coefficients. Results often improve with TR1 models, compared to full wavelength PCR, RR, and PLS models. The SWR subset results are similar to those for the TR1 models using the NIR data and worse with the simulated spectral situations. In general, wavelength selection improves prediction accuracy at a sacrifice to a potential increase in variance and the parsimony remains nearly equivalent compared to full wavelength models. New insights gained from the reported studies provide useful guidelines on when to use full wavelengths or use wavelength selection methods. Specifically, when a small number of large wavelength effects (good sensitivity and selectivity) exist, subset selection by SWR (with caution) and TR1 do well. With a small to moderate number of large to moderate sized wavelength effects, TR1 is better. Lastly, when a large number of small effects are present, full wavelengths with the methods of PCR, RR, or PLS are best.
On-Line Determination of the Molar Ratio between Methanol and Isobutylene in Feedstock of a Methyl Tertiary Butyl Ether Production Plant Using Near-Infrared Spectroscopy
Authors: Yuan Hongfu , Luo Xianhui , Zheng Guojun , Hua Wei , Chu Xiaoli , Lu Wanzhen
Published: January 2007

The molar ratio between methanol and isobutylene (MRMI) is very important to the operation of methyl tertiary butyl ether (MTBE) production units. A new on-line near-infrared (NIR) analytical system was integrated for monitoring the MRMI in real time and was successfully applied in a rubber plant. Calibration models for methanol and isobutylene were established using partial least squares (PLS). The sample temperature effect on the performance of the models is discussed. The MRMI is calculated by methanol content and isobutylene content predicted by NIR. A large benefit has been obtained by the user through controlling the operation of the unit according to the monitoring of the MRMI of the feedstock in real time.
Efficient Characterization for Protein Crystals Using Confocal Raman Spectroscopy
Authors: Noda Kohki , Sato Hidetoshi , Watanabe Shu , Yokoyama Shigeyuki , Tashiro Hideo
Published: January 2007

Confocal Raman spectroscopy was applied to the characterization of various states emerging in the screening of protein crystallization. Four main characterized states, namely single crystals, microcrystals, precipitates, and clear drops without solid materials, appear in a droplet for crystallization; the first three states should be critically distinguished and characterized because of the limitations of visual observation under an optical microscope. Using lysozyme and other proteins, crystallization was performed by the hanging drop vapor diffusion technique and was monitored through an automated confocal Raman system. Prior to the spectroscopic analysis, an optical microscope with a charge-coupled device (CCD) camera and associated image processing software were used to rapidly identify the XY locations to be measured spectroscopically by focusing the laser beam on a test sample. Instead of the current image analysis by optical microscopy, confocal Raman spectroscopy with a high spatial resolution was used to identify the state of protein crystallization. Such real-time Raman monitoring also distinguished real protein crystals from pseudo-protein crystals emerging in a crystallization droplet.
Measurement of Contrast Transfer Function in Super-Resolution Microscopy Using Two-Color Fluorescence Dip Spectroscopy
Authors: Iketaki Yoshinori , Watanabe Takeshi , Bokor Nándor , Omatsu Takashige , Hiraga Takashi , Yamamoto Kimihisa , Fujii Masaaki
Published: January 2007

The contrast transfer function (CTF) of super-resolution microscopy was quantitatively investigated using a fluorescent scale. The scale has minute fluorescent line patterns, finer than 100 nm, and is suitable for measuring CTF in super-resolution microscopy. The measured CTF shows that super-resolution microscopy can indeed improve the optical properties of fluorescent images and enable us to observe a structure with the spatial resolution overcoming the diffraction limit. From the CTF, it has been found that super-resolution microcopy can resolve a 100 nm line-and-space pattern and provides a contrast of 10%. The CTF corresponds to a PSF with a full-width at half-maximum (FWHM) of 130 nm. An evaluation using a 100 nmφ fluorescent bead consistently supports the results given by the CTF for super-resolution microscopy.
High Urinary Concentrations of Activin A in Asphyxiated Full-Term Newborns with Moderate or Severe Hypoxic Ischemic Encephalopathy
Authors: Florio Pasquale , Luisi Stefano , Moataza Bashir , Torricelli Michela , Iman Iskander , Hala Mufeed , Hanna Aboulgar , Petraglia Felice , Gazzolo Diego
Published: January 2007

Background: Hypoxic ischemic encephalopathy (HIE) is a major cause of permanent neurological disabilities in full-term newborns. We measured activin A in urine collected immediately after birth in asphyxiated full-term newborns, and assessed the ability of the measurements to predict the occurrence of perinatal encephalopathy.

Methods: We studied 30 infants with perinatal asphyxia and 30 healthy term neonates at the same gestational age. We recorded routine laboratory variables, cranial assessments by standard cerebral ultrasound, and the presence or absence of neurological abnormalities during the first 7 days after birth. Urinary activin A concentrations were measured at first urination and 12, 24, 48, and 72 h after birth.

Results: Asphyxiated infants were subdivided as follows: group A (n = 18): no or mild HIE with good prognosis and group B (n = 12): moderate or severe HIE with a greater risk of neurological handicap. Activin A concentrations in urine collected at birth (median collection time at first urination <2 h) and at 12, 24, 48, and 72 h from birth were significantly (P <0.0001) higher in asphyxiated newborns with moderate or severe HIE (Group B) than in those with absent of mild HIE (group A) and controls. Concentrations did not differ between group A and controls. Activin A concentrations were >0.08 μg/L at first urination in 10 of 12 patients with moderate or severe HIE but in none of 18 patients with no or mild HIE.

Conclusions: Activin A measurements in urine soon after birth may be a promising tool to identify which asphyxiated infants are at risk of neurological sequelae.
Time-Resolved Immunofluorometric Dual-Label Assay for Simultaneous Detection of Autoantibodies to GAD65 and IA-2 in Children with Type 1 Diabetes
Authors: Ankelo Matti , Westerlund Annette , Blomberg Kaj , Knip Mikael , Ilonen Jorma , Hinkkanen Ari E
Published: January 2007

Background: Autoantibodies to glutamic acid decarboxylase (GADAs), specifically the 65-kDa isoform GAD65, and autoantibodies to the protein tyrosine phosphatase-like molecule IA-2 (IA-2As) predict development of diabetes. Our aim was to develop a time-resolved immunofluorometric (TR-IFMA) dual-label assay method for the simultaneous detection of these autoantibodies and to evaluate the diagnostic sensitivity of the method compared with single-label TR-IFMA and fluid-phase radiobinding assay (RBA) in screening children with type 1 diabetes.

Methods: We incubated combined biotinylated GAD65 and IA-2 proteins, glutathione S-transferase (GST)-IA-2, europium-labeled GAD65, terbium-labeled anti-GST antibody, and serum sample or calibrator and transferred aliquots to a streptavidin-coated 96-well microtiter plate for a second incubation. After washing, we added Delfia Enhancement solution to each well and measured the fluorescence of Eu. We developed the Tb fluorescence signal by use of the Delfia Enhancer solution and measured it. We analyzed serum samples from a cohort of 100 children with newly diagnosed type 1 diabetes.

Results: The correlation coefficients between the autoantibody concentrations measured by dual- and single-label TR-IFMA assays were 0.962 for GADA and 0.874 for IA-2A. Among 100 children with newly diagnosed diabetes, 65 of them were GADA positive in the dual-label assay, 64 in the single-label assay, and 66 in the RBA GADA assay. Seventy-four of the children tested positive for IA-2A in both TR-IFMA assay types, and 79 in the RBA IA-2A assay.

Conclusions: The novel dual-label immunofluorometric assay performed comparably to the separate, single-label GADA and IA-2A assays in screening for β-cell autoimmunity in children with newly diagnosed type 1 diabetes.
Relationship Between C-Reactive Protein and Atherosclerotic Risk Factors and Oxidative Stress Markers Among Young Persons 10–18 Years Old
Authors: Kelishadi Roya , Sharifi Mohsen , Khosravi Alireza , Adeli Khosrow
Published: January 2007

Background: This study was undertaken to determine the association of serum C-reactive protein (CRP) with generalized and abdominal obesity, body fat composition, the metabolic syndrome, and oxidative stress markers among young people.

Methods: We conducted a population-based study of 512 young people, aged 10–18 years. We obtained anthropometric and blood pressure measurements. Fasting blood sugar, total cholesterol (TC), HDL-cholesterol, triglycerides, CRP, malondialdehyde (MDA), and conjugated diene (CDE) were quantified. LDL-cholesterol (LDL-C) was calculated for samples with TG ≤4.52 mmol/L

Results: Mean triglycerides, waist and hip circumferences, percentage body fat, subcutaneous fat, and systolic blood pressure increased significantly with increasing body mass index (BMI). In contrast, the mean LDL and TC were higher in underweight than normal weight individuals, and then increased significantly from normal to higher BMI categories. Mean HDL cholesterol significantly decreased with increasing BMI. Overall, CRP, MDA, and CDE were significantly correlated with measures of abdominal obesity. Serum CRP, MDA, and CDE significantly increased in the upper quartiles of waist circumference. Study participants with higher CRP concentrations were more likely to have metabolic syndrome and high oxidative stress markers.

Conclusion: We found a significant positive association between CRP and oxidative stress markers in healthy young people, as well as an increase in these markers in the upper quartiles of waist circumference, but not BMI. Oxidative stress and CRP may interact in the early inflammatory processes of atherosclerosis.
Processing-Independent Quantitation of Chromogranin A in Plasma from Patients with Neuroendocrine Tumors and Small-Cell Lung Carcinomas
Authors: Børglum Tine , Rehfeld Jens F , Drivsholm Lars B , Hilsted Linda
Published: January 2007

Background: Most neuroendocrine tumors express chromogranin A (CgA). The posttranslational processing of neuroendocrine proteins such as CgA is often specific for the individual tumor. To cope with this variability and improve tumor diagnosis, we developed a processing-independent analysis (PIA) method to measure the total CgA product.

Methods: For PIA, samples underwent trypsin treatment followed by measurement of CgA by the “CgA(340→)” assay, in which the antiserum binds an epitope starting at amino acid 340 of CgA and including amino acid residues located in the C-terminal direction. The diagnostic accuracy of the CgA PIA and 3 sequence-specific assays for CgA were evaluated on plasma samples from patients with neuroendocrine tumors and small-cell lung carcinomas. Furthermore, we investigated whether the CgA plasma concentrations correlated with the tumor burden.

Results: Size-exclusion chromatography of plasma showed that CgA immunoreactivity mainly consisted of high–molecular-weight forms, indicating that neuroendocrine tumors may secrete large amounts of poorly processed CgA. Accordingly, trypsination of plasma from 54 patients with neuroendocrine tumors or small-cell lung carcinomas increased the CgA(340→) immunoreactivity up to 500-fold. Both the CgA(340→) assay and the PIA measured significantly higher plasma concentrations in patients with very extensive disease than in patients with less widespread disease. The diagnostic sensitivity was 0.91 when using the CgA(340→) assay and 0.82 using the CgA PIA.

Conclusion: The CgA(340→) assay and CgA PIA are both useful for diagnosis of neuroendocrine tumors and small-cell lung carcinomas and both assays correlate with tumor burden.
Discovery of Candidate Tumor Markers for Prostate Cancer via Proteomic Analysis of Cell Culture–Conditioned Medium
Authors: Sardana Girish , Marshall John , Diamandis Eleftherios P
Published: January 2007

Objective: Prostate-specific antigen measurement, widely used for early detection of prostate cancer (CaP), suffers from low specificity. Additional tumor markers are needed for the early detection of clinically relevant CaP. Our objective was to perform a qualitative proteomic analysis of conditioned medium (CM) from the CaP cell line PC3(AR)6.

Methods: We used a roller bottle culture system to culture the PC3(AR)6 cell line in chemically defined serum-free medium for 14 days. By using strong anion-exchange chromatography, we fractionated the CM and trypsinized the fractions. The tryptic peptides were further fractionated by reversed-phase C-18 chromatography before being subjected to electrospray ionization tandem mass spectrometry. We used MASCOT software to search the mass spectra generated and organized identified proteins based on their genome ontology classification of cellular location. We used an immunoassay to measure a newly identified secreted protein, Mac-2BP, and kallikreins 5, 6, and 11 in serum samples from CaP patients and healthy men.

Results: We classified 262 proteins according to cellular location; the sample was found to contain a significant proportion of secreted (23%) and membrane (16%) proteins. In a proportion of cancer patients compared with healthy men, we determined by ELISA that serum concentrations of a novel candidate biomarker Mac-2BP were increased.

Conclusions: These identified proteins, and possibly many others found in the CM, may have utility as novel CaP biomarkers.
High-Throughput Microtiter Well-Based Chemiluminometric Genotyping of 15 HBB Gene Mutations in a Dry-Reagent Format
Authors: Glynou Kyriaki , Kastanis Petros , Boukouvala Sotiria , Tsaoussis Vassilis , Ioannou Penelope C , Christopoulos Theodore K , Traeger-Synodinos Joanne , Kanavakis Emmanuel
Published: January 2007

Background: Hemoglobinopathies are the most common inherited diseases worldwide. Various methods for genotyping of hemoglobin, beta (HBB) gene mutations have been reported, but there is need for a high sample-throughput, cost-effective method for simultaneous screening of several mutations. We report a method that combines the high detectability and dynamic range of chemiluminescence with the high allele-discrimination ability of probe extension reactions for simultaneous genotyping of 15 HBB mutations in a high sample-throughput, dry-reagent format.

Methods: We genotyped the HBB mutations IVSI-110G>A, CD39C>T, IVSI-1G>A, IVSI-6T>C, IVSII-745C>G, IVSII-1G>A, FSC6GAG>G-G, −101C>T, FSC5CCT>C−, IVSI-5G>A, FSC8AAG>−G, −87C>G, IVSII-848C>A, term+6C>G, and HbS (cd6GAG>GTG). The method used comprises the following: (a) duplex PCR that produces fragments encompassing all 15 mutations, (b) probe extension reactions in the presence of fluorescein-modified dCTP, using unpurified amplicons, and (c) microtiter well-based assay of extension products with a peroxidase-antifluorescein conjugate and a chemiluminogenic substrate. We used lyophilized dry reagents to simplify the procedure and assigned the genotype by the signal ratio of the normal-to-mutant–specific probe.

Results: We standardized the method by analyzing 60 samples with known genotypes and then validated by blindly genotyping 115 samples with 45 genotypes. The results were fully concordant with sequencing. The reproducibility (including PCR, probe extension reaction, and chemiluminometric assay) was studied for 20 days, and the CVs were 11%–19%.

Conclusions: This method is accurate, reproducible, and cost-effective in terms of equipment and reagents. The application of the method is simple, rapid, and robust. The microtiter well format allows genotyping of a large number of samples in parallel for several mutations.
Technical and Diagnostic Performance of 6 Assays for the Measurement of Citrullinated Protein/Peptide Antibodies in the Diagnosis of Rheumatoid Arthritis
Authors: Coenen Dries , Verschueren Patrick , Westhovens René , Bossuyt Xavier
Published: January 2007

Background: Several anticitrullinated protein/peptide antibodies (ACPA) assays have been reported to be of diagnostic value for rheumatoid arthritis (RA). We evaluated the technical performance and diagnostic accuracy of 6 ELISAs for the detection of antibodies to citrullinated protein/peptide antigens.

Methods: ACPA were determined in 298 serum samples using 6 commercially available ACPA assays. One hundred two samples were from RA patients, including patients with early and established RA, and 196 were from controls, including patients with psoriatic arthritis, connective tissue diseases, organ-specific autoimmune diseases, and a group of consecutive patients for whom a rheumatologist ordered anticyclic citrullinated peptide (CCP) antibodies. The ELISA reagent sets under study were Citrullinated Protein Antibodies (Genesis), Anti-MCV (Orgentec), Immunoscan RA (Euro-Diagnostica), Anti-CCP IgG ELISA (Euroimmun), EliA™ CCP (Phadia), and Quanta Lite™ CCP3 IgG ELISA (Inova). Technical performance (imprecision, linearity, correlation, and agreement) and diagnostic accuracy (sensitivity and specificity) were compared.

Results: Variable technical performance was noted among the different ACPA assays, with some assays displaying poor reproducibility and bad linearity. ACPA results were well correlated among assays with the same antigen specificity, but the numerical values reported for each assay differed widely. Using cutoff values proposed by the manufacturer, diagnostic sensitivities ranged between 69.6% and 77.5% and specificities between 87.8% and 96.4%. The areas under the ROC curves were comparable among the different assays.

Conclusions: Overall diagnostic performance of ACPA assays is comparable among the different assays, but standardization is needed. For some assays, analytical characteristics could be improved.
HPLC–Atmospheric Pressure Chemical Ionization MS/MS for Quantification of 15-F2t-Isoprostane in Human Urine and Plasma
Authors: Haschke Manuel , Zhang Yan Ling , Kahle Christine , Klawitter Jelena , Korecka Magdalena , Shaw Leslie M , Christians Uwe
Published: January 2007

Background: Quantification of F2-Isoprostanes is considered a reliable index of the oxidative stress status in vivo and is valuable in the diagnosis and monitoring of a variety of diseases. Because of complex and lengthy sample preparation procedures, current chromatography/mass spectrometry and immunoassays are impractical for measuring larger numbers of samples. Thus, we developed and validated a semiautomated high-throughput HPLC tandem mass spectrometry assay for the quantification of F2-Isoprostane F2t in human urine and plasma.

Methods: After protein precipitation (500 μL methanol/zinc sulfate added to 500 μL plasma), samples were injected into the HPLC system and extracted online. The extracts were then back-flushed onto the analytical column and detected with an atmospheric pressure chemical ionization-triple quadrupole mass spectrometer monitoring the deprotonated molecular ions [M-H]− of 15-F2t-IsoP (m/z = 353→193) and the internal standard 15-F2t-IsoP-d4 (m/z = 357→197).

Results: In human urine, the assay was linear from 0.025 to 80 μg/L and in human plasma from 0.0025 to 80 μg/L (r2>0.99). Interday accuracy and precision for concentrations above the lower limit of quantification were <10%. Concentrations of 15-F2t-IsoP in urine of 16 healthy individuals ranged from 55–348 ng/g creatinine. In 16 plasma samples from healthy individuals, free 15-F2t-IsoP was detectable in all samples and concentrations were 3–25 ng/L.

Conclusions: Our assay meets all predefined method performance criteria, allows for analysis of >80 samples/day, and has sufficient sensitivity for quantifying 15-F2t-IsoP concentrations in plasma and urine from healthy individuals. It is, thus, suitable for clinical routine monitoring and the analysis of samples from larger clinical trials.
Laboratory Diagnosis of Specific Antibody Deficiency to Pneumococcal Capsular Polysaccharide Antigens
Authors: Jeurissen Axel , Moens Leen , Raes Marc , Wuyts Greet , Willebrords Luc , Sauer Kate , Proesmans Marijke , Ceuppens Jan L , De Boeck Kris , Bossuyt Xavier
Published: January 2007

Background: Measurement of postimmunization antibody response to pneumococcal capsular polysaccharide (caps-PS) is the standard method to identify deficiency of antipolysaccharide antibody production. However, no standardized criteria have been defined for classification of patients into responders or nonresponders to caps-PS.

Methods: We vaccinated 37 healthy children and 39 healthy adults with Pneumovax® and measured the anti–caps-PS antibody response to 5 serotypes. We also measured antipneumococcal antibody titers in 82 patients with increased susceptibility to airway infection. The ELISA was performed according to the 3rd-generation assay format.

Results: The lower 5th percentile (cutoff) concentrations for the postimmunization antibody titer in healthy individuals were 0.67 mg/L, 0.45 mg/L, 0.46 mg/L, 0.31 mg/L, and 1.04 mg/L for serotypes 3, 4, 9N, 18C, and 19F, respectively. In 96% of healthy individuals, antibody responses higher than the cutoff concentration were seen for at least 3 of the 5 serotypes. Nine of 82 patients (11%) failed to mount an adequate antibody response for at least 4 of the 5 serotypes tested, whereas only 1 control (1.3%) failed to do so.

Conclusion: The cutoffs for antibody responses to caps-PS identified in this study appear useful for identifying individuals with an inadequate response to vaccine.
Evaluation of the Risk for Tay-Sachs Disease in Individuals of French Canadian Ancestry Living in New England
Authors: Martin Dianna C , Mark Brian L , Triggs-Raine Barbara L , Natowicz Marvin R
Published: January 2007

Background: The assessment of risk for Tay-Sachs disease (TSD) in individuals of French Canadian background living in New England is an important health issue. In preliminary studies of the enzyme-defined carrier frequency for TSD among Franco-Americans in New England, we found frequencies (1:53) higher than predicted from the incidence of infantile TSD in this region. We have now further evaluated the risk for TSD in the Franco-American population of New England.

Methods: Using a fluorescence-based assay for β-hexosaminidase activity, we determined the carrier frequencies for TSD in 2783 Franco-Americans. DNA analysis was used to identify mutations causing enzyme deficiency in TSD carriers.

Results: We determined the enzyme-defined carrier frequency for TSD as 1:65 (95% confidence interval 1:49 to 1:90). DNA-based analysis of 24 of the enzyme-defined carriers revealed 21 with sequence changes: 9 disease-causing, 4 benign, and 8 of unknown significance. Six of the unknowns were identified as c.748G>A p.G250S, a mutation we show by expression analysis to behave similarly to the previously described c.805G>A p.G269S adult-onset TSD mutation. This putative adult-onset TSD c.748G>A p.G250S mutation has a population frequency similar to the common 7.6 kb deletion mutation that occurs in persons of French Canadian ancestry.

Conclusions: We estimate the frequency of deleterious TSD alleles in Franco-Americans to be 1:73 (95% confidence interval 1:55 to 1:107). These data provide a more complete data base from which to formulate policy recommendations regarding TSD heterozygosity screening in individuals of French Canadian background.
Vehicle and Driver Attributes Affecting Distance from the Steering Wheel in Motor Vehicles
Authors: McFadden Michael , Powers Jennifer , Brown Wendy , Walker Michelle
Published: January 2007

The current study was designed to confirm that female drivers sit closer to the steering wheel than do male drivers and to investigate whether this expected difference in sitting position is attributable to differences in the physical dimensions of men and women. Driver body dimensions and multiple measures of sitting distance from the steering wheel were collected from a sample of 150 men and 150 women. The results confirmed that on average, women sit closer to the steering wheel than men do and that this difference is accounted for by variations in body dimensions, especially height. This result suggests that driver height may provide a good surrogate for sitting distance from the steering wheel when investigating the role of driver position in real-world crash outcomes. The potential applications of this research include change to vehicle design that allows independent adjustment of the relative distance among the driver's seat, the steering wheel, and the floor pedals.
Fuzzy Signal Detection Theory: Basic Postulates and Formulas for Analyzing Human and Machine Performance
Authors: Parasuraman Raja , Masalonis Anthony J. , Hancock Peter A.
Published: January 2007

Signal detection theory (SDT) assumes a Division of Objective truths of "States of the World" into the nonoverlapping categories of signal and noise. The definition of a signal in many real settings, however, varies with context and over time. In the terminology of fuzzy logic, a real-world signal has a value that falls in a range between unequivocal presence and unequivocal absence. The definition of a response can also be nonbinary. Accordingly the methods of fuzzy logic can be combined with SDT, yielding fuzzy SDT. We describe the basic postulates of fuzzy SDT and provide formulas for fuzzy analysis of detection performance, based on four steps: (a) selection of mapping functions for signal and response; (b) use of mixed-implication functions to assign degrees of membership in hits, false alarms, misses, and correct rejections; (c) computation of fuzzy hit, false alarm, miss, and correct rejection rates; and (d) computation of fuzzy sensitivity and bias measures. Fuzzy SDT can considerably extend the range and utility of SDT by handling the contextual and temporal variability of most real-world signals. Actual or potential applications of fuzzy SDT include evaluation of the performance of human, machine, and human-machine detectors in real systems.
Visual Search for Grouped versus Ungrouped Icons in a Computer Interface
Authors: Niemelä Marketta , Saarinen Jukka
Published: January 2007

The paradigm of visual search was used to investigate how participants looked for a target file among distracter files in an icon-based computer interface. The purpose of these experiments was to study the effect of icons and spatial grouping on scanning speed. Does spatial grouping of identical icons increase the scanning speed? Do icons themselves speed up the search for a target file when compared with a condition in which the files are indicated with mere textual labels? Our results showed that both the presence of icons and their grouping had a significant positive effect on the scanning speed. Potential applications of this research include the design of graphics-based interfaces, such as the effective arrangement of icons in an interface.
Effects of Vehicle Interior Geometry and Anthropometric Variables on Automobile Driving Posture
Authors: Reed Matthew P. , Manary Miriam A. , Flannagan Carol A. C. , Schneider Lawrence W.
Published: January 2007

The effects of vehicle package, seat, and anthropometric variables on posture were studied in a laboratory vehicle mockup. Participants (68 men and women) selected their preferred driving postures in 18 combinations of seat height, fore-aft steering wheel position, and seat cushion angle. Two seats differing in stiffness and seat back contour were used in testing. Driving postures were recorded using a sonic digitizer to measure the 3D locations of body landmarks. All test variables had significant independent effects on driving posture. Drivers were found to adapt to changes in the vehicle geometry primarily by changes in limb posture, whereas torso posture remained relatively constant. Stature accounts for most of the anthropometrically related variability in driving posture, and gender differences appear to be explained by body size variation. Large intersubject differences in torso posture, which are fairly stable across different seat and package conditions, are not closely related to standard anthropometric measures. The findings can be used to predict the effects of changes in vehicle and seat design on driving postures for populations with a wide range of anthropometric characteristics.
Frames of Reference for the Display of Battlefield Information: Judgment-Display Dependencies
Authors: Wickens Christopher D. , Thomas Lisa C. , Young Rachel
Published: January 2007

In 2 experiments, U.S. Army soldiers viewed computer-generated displays that presented battlefield information from 3 different frames of reference: a 2D plan view display (with contour lines), a 3D exocentric perspective display, and an interactive 3D immersed display. In Experiment 1, soldiers made geographical judgments. The results suggested that both 3D displays suffered from ambiguity of distance estimates but that the 3D immersed display was most accurate for judging whether a location is directly visible from another. In Experiment 2, the 3D exocentric display was compared with a 3D immersed view, coupled with a small 2D inset map, in a more continuous battlefield scenario in which judgments of enemy activity were made. The findings of 3D ambiguity were replicated from Experiment 1. The accuracy of judgments of enemy activity suffered with the immersed display when information necessary to answer correctly did not appear in the initial forward view and required panning to acquire, reflecting the cognitive demands of integration across different views. This display also hindered soldiers' ability to report changes in enemy activity from one scene to the next. The results of this research will help to provide guidelines for the appropriate choice of computer display technology to assist in designing battlefield visualization aids. Caution should be exercised in choosing immersive viewpoints.
A Componential Model of Human Interaction with Graphs: VI. Cognitive Engineering of Pie Graphs
Authors: Gillan Douglas J. , Callahan Anna Burd
Published: January 2007

This paper proposes and tests the following three-component model of reading a pie graph to estimate segment size: (a) selecting a mentally represented anchor segment (25%, 50%, or 75%), (b) mentally aligning representations of the anchor and target segments, and (c) mentally adjusting the size of the anchor to match the target. Experiment 1 showed that the size difference between the target and closest anchor and the angular displacement of the target from vertical predicted response times (RTs) and absolute error. Experiment 2 demonstrated that an aligned pie graph, designed to reduce the "align" portion of the process, produced faster RTs and lower error than did a regular pie graph. Experiment 3 showed that a pie graph labeled at the anchor values produced the same response times and absolute error as a regular pie graph but that a pie labeled off the anchor points produced a very different pattern of results. The discussion relates the results to the componential model and describes applications in increasing pie graph usability and developing design guidelines. Actual or potential applications of this research include guidelines for graph design and more usable pie graphs.
Applying Quality Control Charts to the Analysis of Single-Subject Data Sequences
Authors: Shehab Randa L. , Schlegel Robert E.
Published: January 2007

Techniques from the field of quality control can be used to classify the quality of individual samples of physical or cognitive performance. After stable baselines have been established for an individual, deviations in performance can be evaluated using control charts. The effectiveness of this approach in evaluating cognitive performance was tested using databases collected under a variety of risk factors. The sensitivity and specificity characteristics of Shewhart, cumulativesum (CUSUM), and exponentially weighted moving average (EWMA) control charts were determined for a total of 174 trials involving 10 participants and 23 cognitive performance assessment measures. The most effective technique in each case was typically a function of the specific performance measure and the type of performance change being evaluated. Sensitivity and specificity for the best techniques were as high as 100%. This study demonstrated the usefulness of quality control charts as a tool to evaluate individual participant performance over time. Actual or potential applications of this research include readiness-to-perform screening of industrial workers in order to improve the health and safety of the workforce.
Medication Schemas and Memory for Automated Telephone Messages
Authors: Morrow Daniel , Carver Lisa M. , Leirer Von O. , Tanke Elizabeth Decker
Published: January 2007

The present study investigated whether older and younger adults use a schema to organize and remember spoken reminder messages for taking medication. Previous research has shown that older and younger adults share preferences for organizing printed instructions for taking medication, suggesting a shared schema. Older and younger participants in Experiment 1 of the present study used a similar schema to organize medication reminder messages. This finding suggests that the medication schema generalizes across communication purpose (to remind or to instruct) as well as across patient age. Medication reminder messages were better understood and remembered when organized to match this schema, whether the reminders were presented as automated telephone messages (Experiment 2) or in printed form (Experiment 3). Schema-compatible organization especially helped people draw inferences from the messages, suggesting that organization helps older and younger adults construct a situation model of the medication-taking task from the messages. Potential applications of organized messages include increasing the impact of automated systems for delivering health services002E
Adaptation and Sensitivity to Postural Change in Sitting
Authors: Helander Martin G. , Little Steven E. , Drury Colin G.
Published: January 2007

We used 3 psychophysics methods to determine perceptible changes in seat height, seat pan angle, and backrest angle using an experimental chair. In the method of adjustment, the chosen chair settings were affected by the initial setting. For example, a high initial setting of the seat height led to a high selected setting and a low setting led to a low value. The difference between settings was referred to as not noticeable difference (NND). The method of limits was used to determine acceptable chair settings using verbal limits such as "too high" and "too low." Using the method of constant stimuli, just noticeable differences (JNDs) were determined for chair height (1.5 cm), seat pan angle (1.2°) and backrest angle (1.7°). The corresponding values for NNDs and verbal limits were about twice as large: chair height (2.5 cm), seat pan angle (4°) and backrest angle (3°). NNDs and verbal limits are unobtrusive measures that are considered more valid than JNDs, which exaggerate the need for adjustability. The results have practical implications for the design of office chairs.