bluuebunny/crossref_metadata_2025_split huggingface dataset:
High‐resolution restoration of dynamic image sequences
Authors: Yu‐Su Wen , Kim Seung P. 
Published: March 2007

AbstractWe investigated an approach to reconstructing high‐resolution images from dynamic image sequences using local spectral analysis. High‐resolution reconstruction from linearly shifted multiple static image frames has previously been studied, in which the aliasing relationship between the spectrum of the original signal and the DFTs of shifted and sampled signals is exploited. In the high‐resolution reconstruction of dynamic image sequences, difficulties occur as a result of nonuniform shifts in the frames. We use loca spectral analysis to achieve high‐resolution reconstruction by overlapped block decomposition and motion compensation. For each block image in a reference frame in the sequence, motion estimation and subpixel registrations are performed against adjacent frames. High resolution reconstruction is performed on such motion‐compensated block‐image sequences. For some blocks containing motion boundaries, high resolution reconstruction is difficult; a new scene emerges or disappears producing inconsistent information. An interpolation technique is used in such blocks to generate the number of pixels consistent with other high‐resolution blocks. The flower‐garden image sequence is used for the computer simulations. The quality of the restored images are very encouraging; the aliasing effects in the original frames are significantly reduced and sharper edges are produced. The overall procedure to generate such higher‐resolution images from a dynamic image sequence is described in detail. The result can be applied to various image sequence restoration applications including up‐conversion of conventional video signals.©1994 John Wiley & Sons Inc
Conformal therapy using maximum entropy optimization
Authors: Sandham William A. , Yuan Yong , Durrani Tariq S. 
Published: March 2007

AbstractConformal therapy offers considerable advantages over conventional radiotherapy treatment, because it has the potential for matchingalmost exactlythe delivered dose distribution to the prescribed dose distribution. Associated (inverse) treatment planning methods address a constrained linear optimization problem. In this article, a method based on maximizing the total entropy of the beam profiles is developed. Maximum entropy optimization constrains the computed dose to be within well‐defined tolerances of the prescribed dose, and has advantages of robustness, fast convergence, and high accuracy. For the work reported here, it is assessed using clinically prescribed irregular target dose volumes based on magnetic resonance imaging and computed tomography images. Results are shown for a two‐dimensional, homogeneous absorption, primary dose computation model, to illustrate the feasibility of the approach; however, the method may be extended to accommodate a more general three‐dimensional model, including inhomogeneities and scatter dose contributions. Optimization of beam offset for a regular angular displacement of beams is also considered, with particular regard to implications on total beam energy, entropy, and computation time.
Methodologic considerations for spiral k‐space functional MRI
Authors: Noll Douglas C. 
Published: March 2007

AbstractMagnetic resonance imaging has recently been developed as a tool to image brain function based on regional changes in blood oxygenation. In this article, we examine the methodologic considerations for functional brain mapping using the spiral k‐space acquisition technique. Gradient design and image reconstruction methods as well as considerations for the selection of imaging parameters are presented. Several sources of image artifacts, along with artifact compensation strategies, are examined. Functional maps of activation in primary motor cortex are usd to demonstrate the effect of image parameter selection and of artifact compensation procedures. These results demonstrate that the spiral k‐space acquisition technique is a rapid, flexible, and robust method for imaging brain activity.
Comparison of T2*‐weighted sequences for functional MRI
Authors: Hu Xiaoping , Erhard Peter , Le Tuang Huu , Kim Seong‐Gi , Menon Ravi , Andersen Peter , Adriany Gregor , Strupp John P. , Uǧurbil Kâmil 
Published: March 2007

AbstractSeveral sequences, including conventional gradient‐echo sequence (e.g., FLASH), gradient‐echo echo‐planar imaging (EPI), T2* prepared ultrafast gradient echo technique (TurboFLASH), and T2*‐weighted spiral sequence, are currently used for T2*‐weighted functional magnetic resonance imaging. This paper presents a comparison of FLASH, gradient‐echo EPI, and T2*‐prepared TurboFLASH. Experimental results have demonstrated that these sequences have different susceptibility to physiologic fluctuation, which is likely the dominant source of noise. EPI images exhibit the lowest relative fluctuation, while images obtained by FLASH and TurboFLASH, respectively, display similar relative fluctuation. Functional maps generated using these sequences are comparable but exhibit different sensitivity to activation from large vessels. Consequently, interpretation of activation results from various maps should take into account the difference in the sequences.
On the use of temporal correlation coefficients for magnetic resonance mapping of functional brain activation: Individualized thresholds and spatial response delineation
Authors: Kleinschmidt Andreas , Requardt Martin , Merboldt Klaus‐Dietmar , Frahm Jens 
Published: March 2007

AbstractFunctional activation of the human visual and motor system was studied by magnetic resonance imaging (MRI) at 2.0 T using dynamic series of oxygenation‐sensitive gradient‐echo images at high spatial resolution. Activation maps were computed by correlating signal intensity time courses with a reference waveform on a pixel‐by‐pixel basis. Although this strategy readily demonstrates stimulus‐related functional cooperativity of activated regions in thresholded maps of correlation coefficients, intertrial variability in the underlying distributions of correlation coefficients precludes the use of correlation coefficients as direct thresholds for defining activation. Because stimulus‐related effects emerge as positive deviations from an otherwise symmetric distribution of correlation coefficients, invariance against intertrial differences as well as adequate visualization of activated areas may be achieved by the following procedure. First, a symmetrized noise distribution is reconstructed from the actual activation map that allows rescaling of correlation coefficients into percentile ranks with respect to the integral of the noise distribution. Second, a high percentile rank (or correspondingly low error probability) can be used as threshold to define primary sites of activation with high specificity. And third, the spatial extent of activation may be delineated by adding directly neighboring pixels with lower values provided their correlation coefficients are high enough to contribute to the positive deviation from the noise distribution. The outlined approach yields robust activation maps but still awaits a more thorough statistical treatment of activation in MRI correlational mapping.
Cognitive task design for FMRI
Authors: Worden Michael , Schneider Walter 
Published: March 2007

AbstractThe quality of functional magnetic resonance imaging (FMRI) data is determined by the quality of the scanning and the control of cognitive behavior of the individual being scanned. This report describes cognitive task design methodology. It is suggested that mapping the stages of cognitive processing is a technically achievable goal with current technology. The behavioral paradigms in FMRI are categorized into technique development and brain mapping paradigms. Technique development paradigms are used to tune scanning parameters with tasks such as visual mapping, motor responding, and language processing. Brain mapping paradigms generally examine uncharacterized areas of cortex. Three stages of brain mapping are described, including: (1) determining the number, location, and stability of active areas; (2) determining the topology and replication of areas; and (3) determining the exogenous/endogenous differentiation of areas. Issues of condition sequencing of tasks within and between trials, statistical analysis, and practical FMRI running are described.
Functional magnetic resonance imaging of language cortex
Authors: Binder Jeffrey R. 
Published: March 2007

AbstractThis review examines recent functional magnetic resonance imaging (FMRI) studies of language cortex. Included are activation studies involving listening to speech, reading, word generation, semantic categorization, and verbal working memory. Where possible we compared FMRI results with similar data obtained using positron emission tomography. Several applications of language FMRI in neurologic patients are presented. Methodologic issues concerning task design are discussed from the perspective of cognitive neuroscience. These issues include the validity of “covert” responses, selection of control tasks, consideration of practice effects, and interpretation of “rest” conditions. FMRI has great potential to clarify the neurophysiologic basis of human language, although this potential remains largely unexplored.
Generalized cross‐validation as a stopping rule for the Richardson‐Lucy algorithm
Authors: Reeves Stanley J. 
Published: March 2007

AbstractThe Richardson‐Lucy (R‐L) algorithm has been widely used to restore degraded astronomical images. This algorithm is nothing more than the expectation‐maximization (EM) algorithm applied to Poisson data. The R‐L method is iterative in nature and converges to a (possibly local) maximum of the likelihood function. Unfortunately, because of the ill‐conditioned nature of the problem, this maximum likelihood estimate may actually be a very poor restoration. One way to prevent degradation of the restoration is to stop the iteration before it reaches convergence. A number of methods have been proposed for determining the optimal stopping point‐the point that provides the best trade‐off between restoring the image and amplifying the noise. Cross‐validation (CV) has recently been proposed as an advantageous method for determining the optimal stopping point. We propose a different form of CV based on generalized cross‐validation (GCV) that overcomes some of the difficulties of CV. We derive a GCV‐based criterion for the R‐L algorithm that can be efficiently evaluated at each iteration. We present examples displaying the power of the stopping rule and discuss the abilities and shortcomings of the method.
Bystander killing of breast cancer MCF‐7 cells by MDA‐MB‐231 cells exposed to 5‐fluorouracil is mediated via Fas
Authors: Chhipa Rishi Raj , Bhat Manoj Kumar 
Published: March 2007

AbstractThe major drawback with cancer therapy is the development of resistant cells within tumors due to their heterogeneous nature and due to inadequate drug delivery during chemotherapy. Therefore, the propagation of injury (“bystander effect” (BE)) from directly damaged cells to other cells may have great implications in cancer chemotherapy. The general advantage of the bystander cell killing phenomenon is the large therapeutic index that can be achieved. Experiments suggest that this phenomenon is detected in radiation therapy as well as in gene therapy in conjunction with chemotherapy. In the present study, we developed an original in vitro model dedicated to the exploration of bystander cytotoxicity induced during breast carcinoma chemotherapy. In brief, we investigated this perpetuation of injury on untreated bystander MCF‐7 breast cancer cells which were coplated with 5‐fluorouracil (5‐FU)‐treated MDA‐MB‐231 breast cancer cells. To achieve this goal, a specific in vitro coculture model which involved mixing of aggressive MDA‐MB‐231 breast cancer cells with enhanced green fluorescent protein (EGFP) expressing stable clone of non‐metastatic MCF‐7 breast cancer cells (MCF‐EGFP), was used. A bystander killing effect was observed in MCF‐EGFP cells cocultured with MDA‐MB‐231 cells pretreated with 5‐FU. The striking decrease in MCF‐EGFP cells, as detected by assaying for total GFP intensity, is mediated by activation of Fas/FasL system. The implication of Fas in MCF‐EGFP cell death was confirmed by using antagonistic anti‐FasL antibody that reverses bystander cell death by blocking FasL on MDA‐MB‐231 cells. In addition, inhibition of CD95/Fas receptor on the cell surface of MCF‐EGFP cells by treatment with Pifithrin‐alpha, a p53 specific transactivation inhibitor, partially abrogated the sensitivity of bystander MCF‐EGFP cells. Our data, therefore, demonstrates that the Fas/FasL system could be considered as a new determinant for chemotherapy‐induced bystander cell death in breast cancers. J. Cell. Biochem. J. Cell. Biochem. 101: 68–79, 2007. © 2007 Wiley‐Liss, Inc.
Excited state properties, fluorescence energies, and lifetime of a poly(fluorene‐pyridine) copolymer, based on TD‐DFT investigation
Authors: Chidthong Rungtiwa , Hannongbua Supa , Aquino Adelia J. A. , Wolschann Peter , Lischka Hans 
Published: March 2007

AbstractThe structural and electronic properties of the fluorene‐pyridine copolymer (FPy)n, (n = 1–4) were investigated theoretically by means of quantum mechanical calculations based on density functional theory (DFT) and time‐dependent DFT (TD‐DFT) using the B3LYP functional. Geometry optimizations of these oligomers were performed for the ground state and the lowest excited state. It was found that (FPy)n is nonplanar in its ground state, whereas a more pronounced trend toward planarity is observed in the S1 state. Absorption and fluorescence energies have been extrapolated to infinite chain length making use of their good linearity with respect to 1/n. An extrapolated value of 2.64 eV is obtained for vertical excitation energy. The S1←S0 electronic excitation is characterized as a highest occupied molecular orbital to lowest unoccupied molecular orbital transition and is dominating in terms of oscillator strength. Fluorescence energies and radiative lifetime were calculated as well. The obtained results indicate that the fluorescence energy and radiative lifetime of (FPy)n are 2.16 eV and 0.38 ns, respectively. The decrease of fluorescence energy and radiative lifetime with the increase in the chain length is discussed. © 2007 Wiley Periodicals, Inc. J Comput Chem, 2007
Current status of homogeneous enzyme immunoassays
Authors: Nakamura Robert M. , Robbins Bruce A. 
Published: March 2007

AbstractRecent advances in homogeneous enzyme immunoassays (EIAs) are discussed. EIA methods have been developed with comparable sensitivity to those of radioimmunoassay (RIA). EIAs have become established in many clinical laboratories and are generally being employed for: 1) homogeneous assay of low molecular weight compounds such as drugs and antibiotics present in biological samples at relatively high concentrations, 2) qualitative and semiquantitative assays for viral, bacterial, fungal, and parasitic antigens and antibodies, 3) tissue immunohistochemical localization of antigens and antibodies, and 4) alternatives to RIA in smaller laboratories. This paper discusses the principles and applications of newer homogeneous assays such as avidin‐biotin enzyme, hybrid antibody, insoluble sub state and cloned enzyme donor, and electrochemical immunoassays. Future instrumentation for EIAs with the use of biosensors is also discussed.
Performance of the tandem ICON strep A® enzyme immunoassay system for detection of group a streptococci from oropharyngeal swabs
Authors: Kellogg James A. , Bankert David A. , Levisky John S. 
Published: March 2007

AbstractThe Tandem ICON Strep A® (TISA Hybri‐tech, Inc.) was compared to culture for detection of group A streptococci, using throat swabs obtained from patients with symptoms of pharyngitis. Each swab was first inoculated to a 5% sheep blood agar plate and then tested for streptococcal antigen using the TISA. Cultures were incubated anaerobically at 35°C for 36 to 48 hours unless positive following overnight incubation. Group A streptococci were recovered in culture and serologically identified from 163 (21.0%) of the 776 swabs processed. The sensitivity and specificity of the TISA were 76.7% and 96.4%, respectively, whereas the predictive values of positive (PVP) and negative (PVN) results were 85.0% and 94.0%, respectively. However, TISA specificity ranged from 93.6% in one of 3 lots tested to 99.1% in another (P < 0.005). The PVP of the former lot was 76.3%, whereas that of the latter was 95.6% (P < 0.005). The relative lack of sensitivity and lot‐to‐lot variation observed with the TISA in this study indicate that the product is not a suitable alternative to a competently performed throat culture.
Impaired interleukin‐2 production by t‐lymphocytes in polycythemia vera
Authors: Paul Cassandra C. , Baumann Michael A. 
Published: March 2007

AbstractT‐lymphocyte function was investigated in a group of eight patients with polycythemia vela (PV) and 13 normals. Responsiveness of T‐cells to stimulation by mitogen was significantly impaired in the PV patients (p = .02). Analysis of immune cell subpopulation composition by assessment of cell surface phenotype did not reveal imbalances that could account for impaired T‐cell proliferative ability in PV patients. Addition of recombinant human interleukin‐1 to PV mononuclear cell cultures did not enhance proliferative ability.Addition of recombinant human interleu‐kin‐2 to cultures had no effect on maximum mitogen stimulation in normals but significantly improved responses in PV patients (p < .02), correcting them to normal levels. Measurement of interleukin‐2 production by stimulated cultured mononuclear cells confirmed subnormal IL‐2 production by PV T‐cells (p < .00005). Impaired IL‐2 production could conceivably contribute to the pathogenesis of PV by limiting the ability of IL‐2‐dependent cells to regulate hematopoiesis.
Expression of the cd4 molecule on acute nonlymphocytic leukemia (anll) cell lines
Authors: Neudorf Steven , Delaat Cynthia , Jones Marilyn , Neudorf Steven 
Published: March 2007

AbstractMature and immature monocytes express the CD4 molecule similar to that expressed on lymphocytes. Since monocytes and cells of myeloid lineage are derived from a common progenitor, we studied a panel of nine myeloid leukemia cell lines for the expression of the CD4 molecule. We found that six of nine myeloid leukemia cell lines (U937, KG1‐B, HL‐60, THP‐1, HEL 92.1.7, KMOE) expressed CD4, the exceptions being the erythroleukemia line K562, myeloblast line KG1‐REV, and megakaryocytic line, CHRF‐288. SDS‐PAGE analysis of HL‐60 cells immunoprecipitated with OKT4 showed the presence of a 55kd molecule similar in weight to that seen on lymphocytes. These data suggest that some myeloid progenitor cells express the CD4 molecule and that the CD4 may have a broader distribution within hematopoietic cells.
Ca 72‐4 radioimmunoassay for the detection of the tag‐72 carcinoma‐associated antigen in serum of patients
Authors: Gero Eva J. , Melsheimer Richard , Colcher David , Ferroni Patrizia , Giani Silvia , Schlom Jeffrey , Kaplan Paul , Giani Silvia 
Published: March 2007

AbstractMonoclonal antibody (MAb)B72.3 has been used to detect the presence of TAG‐72 in the serum of carcinoma patients. We have developed new anti‐TAG‐72 MAbs and have selected one of these, CC49, as the “catcher” MAb with 125I–B72.3 as the detecting antibody in a double‐determinant immunoradiometric assay. This combination enabled the development of a sequential assay (designated CA 72‐4) that showed optimal quantitative properties as demonstrated by such parameters as linear dose‐response, high reproducibility, and lack of serum‐matrix and “hook‐back” effects.Only 3.5% of 744 normal sera and 6.7% of 134 sera from patients with benign gastrointestinal diseases had TAG‐72 levels greater than 6 U/ml. Approximately 40% of 303 patients with gastrointestinal malignancies had serum TAG‐72 levels of greater than 6 U/ml (55% of the patients with advanced disease). Thirty‐six percent of patients with adenocarcinomas of the lung and 24% of patients with ovarian cancer (53% stage IV patients) also had elevated serum TAG‐72 levels.A poor correlation was found between the carcinoembryonic antigen (CEA) and TAG‐72 values of sera obtained from gastric cancer patients. Thirty‐four percent of CEA negative cases were scored positive in the CA 72‐4 assay, suggesting the complementarity of the CA 72‐4 assay to CEA assays in the analysis of sera from patients with certain malignancies.
Natural killer cytotoxicity in the diagnosis of immune dysfunction: Criteria for a reproducible assay
Authors: Whiteside Theresa L. , Bryant John , Herberman Ronald B. , Day Roger 
Published: March 2007

AbstractCurrent evidence indicates that natural killer (NK) cells, which are large granular lymphocytes that mediate non‐major histocompatibility complex (MHC)‐restricted cytotoxicity and antibody‐dependent cytotoxicity and that are involved in multiple regulatory, developmental, and immunologic processes, are important in health. Immunodeficiency states presenting with low NK activity are often associated with malignancies, chronic viral infections, or autoimmune diseases. Monitoring of NK function appears to be indicated as an aid to diagnosis, prognosis, and follow‐up after therapy. Reliable performance of NK assays in a clinical laboratory requires that uniform criteria be established and followed for the acceptability of results. Statistical analysis of daily variability can be of great assistance in identifying and tracking sources of error, but routine statistical adjustments are not generally advisable. The quality control program described here provides a degree of assurance that this cytotoxicity assay can be dependable whether performed at one time point or serially. The successful implementation of this program requires laboratory resouces, biostatistical support, and interpretative skills, all of which are available in a modern clinical laboratory.
A sandwich enzyme immunoassay for detecting and measuring alzheimer's disease‐associated proteins in human brain tissue
Authors: Ghanbari Hossein A , Ghanbari Hossein A , Kozuk Terry , Miller Barney E. , Riesing Sue 
Published: March 2007

AbstractA simple, fast, and reliable immunoassay has been developed to detect and measure Alzheimer's disease‐associated proteins (ADAPs) in human brain tissue. This assay, called ALZ‐EIA (brain), was developed for Abbott's quantum system, in which 1/4‐in. beads are used as solid phase. The beads were coated with polyclonal IgG purified from sera obtained from rabbits immunized with a highly enriched Alzheimer's disease brain protein fraction for ADAP. The antigen (ADAP) is effectively captured by the polyclonal IgG coated on the beads. ALZ‐50 (a mouse monoclonal IgM) is used as the detection antibody, and bound ALZ‐50 is subsequently quantified by a horseradish peroxidase‐linked goat antimouse IgM and appropriate substrate. The assay is linear up to 0.5 absorbance units (r = 0.9), reproducible (CV less than lo%), sensitive, and specific. With preformulated reagents and standard supplies, the assay is simple and rapid; 120 data points can readily be generated in about 4 hr.