bluuebunny/crossref_metadata_2025_split huggingface dataset:
Origin of feathers: Feather beta (β) keratins are expressed in discrete epidermal cell populations of embryonic scutate scales
Authors: Sawyer Roger H. , Salvatore Brian A. , Potylicki Ta‐Tanisha F. , French Jeffery O. , Glenn Travis C. , Knapp Loren W. 
Published: January 2003

AbstractThe feathers of birds develop from embryonic epidermal lineages that differentiate during outgrowth of the feather germ. Independent cell populations also form an embryonic epidermis on scutate scales, which consists of peridermal layers, a subperiderm, and an alpha stratum. Using an antiserum (anti‐FβK) developed to react specifically with the beta (β) keratins of feathers, we find that the feather‐type β keratins are expressed in the subperiderm cells of embryonic scutate scales, as well as the barb ridge lineages of the feather. However, unlike the subperiderm of scales, which is lost at hatching, the cells of barb ridges, in conjunction with adjacent cell populations, give rise to the structural elements of the feather. The observation that an embryonic epidermis, consisting of peridermal and subperidermal layers, also characterizes alligator scales (Thompson, 2001. J Anat 198:265–282) suggests that the epidermal populations of the scales and feathers of avian embryos are homologous with those forming the embryonic epidermis of alligators. While the embryonic epidermal populations of archosaurian scales are discarded at hatching, those of the feather germ differentiate into the periderm, sheath, barb ridges, axial plates, barbules, and marginal plates of the embryonic feather filament. We propose that the development of the embryonic feather filament provides a model for the evolution of the first protofeather. Furthermore, we hypothesize that invagination of the epidermal lineages of the feather filament, namely the barb ridges, initiated the formation of the follicle, which then allowed continuous renewal of the feather epidermal lineages, and the evolution of diverse feather forms. J. Exp. Zool. (Mol. Dev. Evol.) 295B:12–24, 2003 © 2003 Wiley‐Liss, Inc.
Protein evolution: structure‐function relationships of the oncogene beta‐catenin in the evolution of multicellular animals
Authors: Schneider Stephan Q. , Finnerty John R. , Martindale Mark Q. 
Published: January 2003

AbstractBeta‐catenin functions as a cytoskeletal linker protein in cadherin‐mediated adhesion and as a signal mediator in wnt‐signal transduction pathways. We use a novel integrative approach, combining evolutionary, genomic, and three‐dimensional structural data to analyze and trace the structural and functional evolution of beta‐catenin genes. This approach also enabled us to examine the effects of gene duplication on the structure and function of beta‐catenin genes in Drosophila, C. elegans, and vertebrates. By sampling a large number of different taxa, we identified both ancestral and derived motifs and residues within the different regions of the beta‐catenin proteins. Projecting amino acid substitutions onto the three‐ dimensional structure established for mouse beta‐catenin, we identified specific domains that exhibit loss and gain of selective constraints during beta catenin evolution. Structural changes, changes in the amino acid substitution rate, and the appearance of novel functional domains in beta‐catenin can be mapped to specific branches on the metazoan tree. Together, our analyses suggest that a single, beta‐catenin gene fulfilled both adhesion and signaling functions in the last common ancestor of metazoans some 700 million years ago. In addition, gene duplications facilitated the evolution of beta‐catenins with novel functions and allowed the evolution of multiple, single‐function proteins (cell adhesion or wnt‐signaling) from the ancestral, dual‐function protein. Integrative methods such as those we have applied here, utilizing the ‘natural experiments’ present in animal diversity, can be employed to identify novel and shared functional motifs and residues in virtually any protein among the proteomes of model systems and humans. J. Exp. Zool. (Mol. Dev. Evol.) 295B:25–44, 2003. © 2003 Wiley‐Liss, Inc.
Telomerase activity is widespread in adult somatic tissues of Xenopus
Authors: Bousman Sylvia , Schneider Gerard , Shampay Janis 
Published: January 2003

AbstractChromosome ends, or telomeres, are maintained by telomerase. Work in selected vertebrates has implied that telomerase is often repressed in differentiated cells, and telomere erosion results in senescence of cultured cells. Tissues from mature Xenopus laevis frogs were examined for telomerase enzymatic activity with the TRAP (telomere repeat amplification protocol) assay. All tissues contained active telomerase, most abundantly in testis, spleen, liver, and embryos; activity was less abundant but still readily detectable with < 100 ng of protein extract from brain and muscle tissues. Activity in somatic tissues of the diploid Xenopus tropicalis suggests this condition is not limited to the polyploid members of the genus, and that extensive differentiation‐linked telomerase repression does not occur in Xenopus. J. Exp. Zool. (Mol. Dev. Evol.) 295B:82–86, 2003. © 2003 Wiley‐Liss, Inc.
In the margins of scientific dialogue: Evart Van Dieren contra psychoanalysis
Authors: Bos Jaap 
Published: January 2003

AbstractEvart Van Dieren (1861–1940), a Dutch general practitioner who had a passionate aversion against psychoanalysis, wrote two particularly polemical books contra Freud but nevertheless did not succeed in generating much response. In this paper, some of his objections against psychoanalysis are briefly examined and compared with some present day arguments against Freud by Grünbaum and Crews, with the purpose of finding an answer to the question: What does it take to be a successful or unsuccessful critic? © 2003 Wiley Periodicals, Inc.
“Automatism” and the emergence of dynamic psychiatry
Authors: Crabtree Adam 
Published: January 2003

AbstractThis article is about the clash of two explanatory paradigms, each attempting to account for the same data of human experience. In the first half of the nineteenth century, physiologists investigated reflex actions and applied a recently coined word, “automatism,” to describe actions which, although seeming to arise from higher centers, actually result from automatic reaction to sensory stimuli. Experiments with spinal reflexes led to the investigation of the reflex action of the brain or “cerebral automatisms.” Reflex actions of this kind were used to explain everything from acting compulsively to composing symphonies. Physiological explanations of phenomena of this kind seemed insufficient to some and, in the 1880s, Frederic Myers and Pierre Janet developed psychological frameworks for understanding these phenomena, positing hidden centers of intelligence at work in the individual, outside ordinary awareness, which produce what came to be called “psychological automatisms.” Their attempts to unify this psychological framework with the existing physiological one failed. Nevertheless, their work played a crucial role in paving the way for what Ellenberger called dynamic psychiatry, which accepts the reality of an unconscious dynamic of the psyche. © 2003 Wiley Periodicals, Inc.
B. F. Skinner's technology of behavior in American life: From consumer culture to counterculture
Authors: Rutherford Alexandra 
Published: January 2003

AbstractFrom the 1940s through the 1970s, articles in popular magazines and newspapers presented B. F. Skinner in a wide array of guises, from educational revolutionary and utopian to totalitarian and fascist. Understanding these diverse, and often contradictory, portrayals requires a consideration of the social and political discourses in which they were embedded. In this paper, I suggest that reports of Skinner's work were influenced by a number of cultural categories, from the better living campaign of the 1950s, to the counterculture crusade of the late 1960s. Through this examination, a multifaceted rendering of Skinner's public image that takes into account the nature of his work, the context in which it was produced, and the culture in which it was received is revealed. I propose that the received view of Skinner as maligned behaviorist actually obscures the complexity of his relationship with psychology's public throughout this period. © 2003 Wiley Periodicals, Inc.
Versemaking and lovemaking—W. B. Yeats' “strange second puberty”: Norman Haire and the Steinach rejuvenation operation
Authors: Wyndham Diana 
Published: January 2003

AbstractThis article examines the Steinach rejuvenation operation (a vasectomy) which Norman Haire performed on W. B. Yeats in 1934: while this method is now discredited, many others are still used in similar attempts to “cure” old age and restore youthful vitality. The article deals substantially with ideas which were popular among well‐read people and intellectuals in the 1920s and 1930s and discusses whether the poet's late‐in‐life burst of creativity was caused by a medical breakthrough, Haire's more general medical advice, the placebo effect, or by a combination of factors: questions which still have relevance to theories about age, sexuality, and mind‐body relationships. © 2003 Wiley Periodicals, Inc.
The use of the resonant mirror biosensor to detect point mutations, as demonstrated with synthetic oligonucleotides
Authors: Momynaliev K. T. , Govorun V. M. , Gnedenko O. , Ivanov Yu. D. , Archakov A. I. 
Published: January 2003

AbstractThe possibility of using the resonant mirror biosensor to detect point substitutions in oligonucleotides was demonstrated with a fragment of the Helicobacter pylori 23S rRNA gene, point mutations in which are responsible for clarythromycin resistance. Conditions were optimized for the interaction of a probe immobilized on the sensing surface with targets containing various nucleotide substitutions. A probe allowing reliable discrimination of mutant targets was selected. The mismatch position in the probe was shown to affect the kinetic parameters (response) of hybridization with mutant targets, reporting not only the position, but also the character (G or C) of a substitution. Copyright © 2003 John Wiley & Sons, Ltd.
RNA aptamers specific for bovine thrombin
Authors: Liu Xuemei , Zhang Dajin , Cao Guojun , Yang Guang , Ding Hongmei , Liu Gang , Fan Ming , Shen Beifen , Shao Ningsheng 
Published: January 2003

AbstractBovine thrombin is widely used in clinical wound healing after surgery. There is 85% homology between bovine thrombin and human thrombin, so most antibodies against bovine thrombin cross‐react with human thrombin. Rare antibodies against bovine thrombin but not cross‐reacting with human thrombin have been reported. RNA ligands (aptamers) have been used to bind to target molecules with sometimes higher specificity than antibodies. Here we report the isolation of aptamers specific for bovine thrombin by systematic evolution of ligands by exponential enrichment (SELEX) from an RNA pool containing a 25‐nucleotide randomized region. After seven rounds of selection, two aptamers specific for bovine thrombin were identified with a Kd of 164 and 240 nM, respectively. Significantly, these aptamers do not bind to human thrombin. Secondary structure prediction revealed potential stem‐loop structures for these RNAs. Both RNA aptamers inhibit only bovine thrombin‐catalyzed fibrin clot formation in vitro. Competition assay results suggested that the RNA aptamers might bind to the electropositive domain of bovine thrombin, that is, heparin‐binding site, instead of fibrinogen‐recognition exosite. The resulting bovine‐specific thrombin inhibitor might be used in some clinical applications when bovine thrombin activity needs to be contained or in research where human and bovine thrombin need to be distinguished. Copyright © 2003 John Wiley & Sons, Ltd.
Abbreviations used:

SELEX

systematic evolution of ligands by exponential enrichment
8.0‐Tesla human MR system: Temperature changes associated with radiofrequency‐induced heating of a head phantom
Authors: Kangarlu Allahyar , Shellock Frank G. , Chakeres Donald W. 
Published: January 2003

AbstractPurposeTo investigate if the heat induced in biological tissues by typical radio frequency (RF) energy associated with an 8.0‐Tesla magnetic resonance (MR) system causes excessive temperature changes.Materials and MethodsFluoroptic thermometry was used to measure temperatures in multiple positions in a head phantom made of ground turkey breast. A series of experiments were conducted with measurements obtained at RF power levels ranging from a specific absorption rate (SAR) of up to 4.0 W/kg for 10 minutes.ResultsThe highest temperature increases were up to 0.7°C. An inhomogeneous heating pattern was observed. In general, the deep regions within the phantom registered higher temperature increases compared to the peripheral sites.ConclusionThe expectation of an inhomogeneous RF distribution in ultra high field systems (> 4 T) was confirmed. At a frequency of 340 MHz and in‐tissue RF wave length of about 10 cm, the RF inhomogeneity was measured to create higher temperatures in deeper regions of a human head phantom compared to peripheral tissues. Our results agree with the computational electromagnetic calculations for such frequencies. Importantly, these experiments indicated that there were no regions of heating that exceeded the current FDA guidelines. J. Magn. Reson. Imaging 2003;17:220–226. © 2003 Wiley‐Liss, Inc.
Multispectral magnetic resonance image analysis using principal component and linear discriminant analysis
Authors: Witjes Han , Rijpkema Mark , van der Graaf Marinette , Melssen Willem , Heerschap Arend , Buydens Lutgarde 
Published: January 2003

AbstractPurposeTo explore the possibilities of combining multispectral magnetic resonance (MR) images of different patients within one data matrix.Materials and MethodsPrincipal component and linear discriminant analysis was applied to multispectral MR images of 12 patients with different brain tumors. Each multispectral image consisted of T1‐weighted, T2‐weighted, proton‐density‐weighted, and gadolinium‐enhanced T1‐weighted MR images, and a calculated relative regional cerebral blood volume map.ResultsSimilar multispectral image regions were clustered, while dissimilar multispectral image regions were scattered in a single plot. Both principal component and linear discriminant analysis allowed discrimination between healthy and tumor regions on the image. In addition, linear discriminant analysis allowed discrimination between oligodendrogliomas and astrocytomas. However, the discriminant analysis method was partially capable of recognizing the tumor identity in unknown multispectral images.ConclusionThe proposed method may help the radiologist in comparing multispectral MR images of different patients in a more easy and objective way. J. Magn. Reson. Imaging 2003;17:261–269. © 2003 Wiley‐Liss, Inc.
MR findings of collateral circulation are more accurate measures of hemodynamic significance than arm‐leg blood pressure gradient after repair of coarctation of the aorta
Authors: Araoz Philip A. , Reddy Gautham P. , Tarnoff Harold , Roge Claude L. , Higgins Charles B. 
Published: January 2003

AbstractPurposeTo determine the relationship between percent stenosis and three indicators of hemodynamic significance—arm–leg blood pressure gradient, direct visualization of collaterals, and percent increase flow from proximal to distal descending thoracic aorta—in patients with prior repair of coarctation of the aorta (CoA).Materials and MethodsMagnetic resonance imaging (MRI) examinations of 19 patients with prior repair of CoA were retrospectively reviewed. Percent stenosis was compared to the arm–leg blood pressure gradient as obtained from chart review, the depiction of collaterals by gadolinium‐enhanced magnetic resonance angiography (MRA), and the percent increased flow in the distal thoracic aorta as measured by velocity‐encoded cine MRI. Some imaging series or blood‐pressure values were not available in some patients. All of the data were available for 15 of the 19 patients.ResultsThe arm–leg blood pressure gradient showed no statistical association with percent stenosis (R2 = 0.10, P = 0.22), direct visualization of collaterals (P = 0.80), or percent increase in flow (R2 < 0.01, P = 0.85). Percent stenosis did show association with visualization of collaterals (P = 0.01) and increase flow (R2 = 0.62, P < 0.01).ConclusionThe arm–leg blood pressure gradient is not a reliable indicator of hemodynamic significance of restenosis in patients with prior repair of CoA. Direct visualization of collateral vessels by MRA and percent increase in flow from proximal to distal descending thoracic aorta are reliable indicators of hemodynamic significance. J. Magn. Reson. Imaging 2003;17:177–183. © 2003 Wiley‐Liss, Inc.
Variation correction algorithm: Analysis of phase suppression and thermal profile fidelity for proton resonance frequency magnetic resonance thermometry at 0.2 T
Authors: Barkauskas Kestutis J. , Lewin Jonathan S. , Duerk Jeffrey L. 
Published: January 2003

AbstractPurposeTo develop and analyze the performance of the variation correction algorithm (VCA), a phase correction technique that mitigates the contribution of background phase variations by combining accurate alignment of echoes, K‐space‐based phase correction (as opposed to spatial polynomials), and extraction of alias‐free phase difference images.Materials and MethodsA series of echo‐shifted gradient‐recalled echo (GRE) images was processed with K‐space alignment and phase corrected with increasing sizes of M × M masks of central K‐space coefficients. The extent of background phase variation suppression due to magnet field drift was assessed. Further, a simulated thermal profile was superimposed on the same data in a related experiment. Residual errors in reconstructed simulated thermal profiles were quantitatively characterized to estimate algorithm performance.ResultsUsing a 3 × 3 K‐space mask, the VCA was able to 1) maintain the typical mean backround error in a 35 × 35 pixel region of interest (ROI) at −0.1°C; and 2) reconstruct, relative to the applied thermal profile, a phase‐corrected profile that typically contains a 1.7°C underestimation of peak temperature difference and a mean error along the 60°C line of −0.8°C.ConclusionThe results suggest that thermal profiles can be accurately reconstructed at 0.2 T using the VCA, even in the presence of over 1 ppm spatially and temporally dependent field drift over a 1‐hour time frame. J. Magn. Reson. Imaging 2003;17:227–240. © 2003 Wiley‐Liss, Inc.
Can dynamic susceptibility contrast magnetic resonance imaging perfusion data be analyzed using a model based on directional flow?
Authors: Thacker N.A. , Scott M.L.J. , Jackson A. 
Published: January 2003

AbstractPurposeTo examine the implications of a physiological model of cerebral blood that uses the contradictory assumption that blood flow in all voxels of DSCE‐MRI data sets is directional in nature. Analysis of dynamic susceptibility contrast‐enhanced magnetic resonance imaging (DSCE‐MRI) uses techniques based on indicator dilution theory. Underlying this approach is an assumption that blood flow through pixels of gray and white matter is entirely random in direction.Materials and MethodsWe have used a directional flow model to estimate theoretical blood flow velocities that would be observed through normal cerebral tissues. Estimates of flow velocities from individual pixels were made by measuring the mean transit time for net flow (nMTT). Measurements of nMTT were made for each voxel by estimating the mean difference in contrast arrival time between each of the adjacent six voxels.ResultsExamination of the spatial distribution of contrast arrival time from DSCE‐MRI data sets in normal volunteers demonstrated clear evidence of directional flow both in large vessels and in gray and white matter. The mean velocities of blood flow in gray and white matter in 12 normal volunteers were 0.25 ± 0.013 and 0.21 ± 0.014 cm/second, respectively, compared to predicted values of 0.25 and 0.18 cm/second. These values give measured nMTT for a 1‐mm isotropic voxel of gray and white matter of 0.45 ± 0.12 and 0.52 ± 0.11 seconds, respectively, compared to predicted values of 0.47 and 0.55 seconds.ConclusionA directional model of blood flow provides an alternative approach to the calculation of cerebral blood flow from (CBF) DSCE‐MRI data. J. Magn. Reson. Imaging 2003;17:241–255. © 2003 Wiley‐Liss, Inc.
Feasibility of abdomino‐pelvic T1‐weighted real‐time thermal mapping of laser ablation
Authors: Dick Elizabeth A. , Wragg Paul , Joarder Rita , de Jode Michael , Lamb Gabrielle , Gould Stuart , Gedroyc Wladyslaw M.W. 
Published: January 2003

AbstractPurposeTo prove the hypothesis that T1‐weighted (T1W) thermal mapping is reliable and achievable in magnetic resonance (MR)‐guided laser tumor ablation.Materials and MethodsNear real‐time gray and color‐scale T1W thermal maps in 111 MR‐guided laser thermal ablations (LTA) of liver, kidney, and uterine tumors were studied. After laser fiber placement, near real‐time gray and color‐scale thermal maps were produced. Previous work showed T1 signal is inversely proportional to temperature below 55°C (the point of irreversible necrosis).ResultsThermal mapping was successful in 84% of uterine, 74% of hepatic, and 20% of renal ablations. For hepatic and uterine tumors, size and conspicuity of thermal lesions were significantly greater on subtracted colorized images rather than gray‐scale raw image mapping (P = 0.001, paired Student's t‐test). Patient movement (N = 24), fiber charring N = 2), magnetic field distortion, and reconstruction errors (N = 2) caused mapping failure. For both renal and hepatic tumors, comparison of near real‐time T1W colorized thermal map and follow up gadolinium‐enhanced MR imaging revealed moderate correlation (Pearson correlation coefficient of 0.55 and 0.5, respectively).ConclusionIn hepatic, renal, and uterine thermal maps, the color scale produced significantly greater sized lesions with significantly greater conspicuity than the gray scale. T1W thermal mapping was reliable and successfully achieved in 73.7% of procedures, and predicted the ablated area of the tumor moderately well. J. Magn. Reson. Imaging 2003;17:197–205. © 2003 Wiley‐Liss, Inc.
MRI measurement of time‐resolved wall shear stress vectors in a carotid bifurcation model, and comparison with CFD predictions
Authors: Papathanasopoulou Panorea , Zhao Shunzhi , Köhler Uwe , Robertson Malcolm B. , Long Quan , Hoskins Peter , Yun Xu X. , Marshall Ian 
Published: January 2003

AbstractPurposeTo study pulsatile fluid flow in a physiologically realistic model of the human carotid bifurcation, and to derive wall shear stress (WSS) vectors.Materials and MethodsWSS vectors were calculated from time‐resolved 3D phase‐contrast (PC) MRI measurements of the velocity field. The technique was first validated with sinusoidal flow in a straight tube, and then used in a model of a healthy human carotid bifurcation. Velocity measurements in the inflow and outflow regions were also used as boundary conditions for computational fluid dynamics (CFD) calculations of WSS, which were compared with those derived from MRI alone.ResultsThe straight tube measurements gave WSS results that were within 15% of the theoretical value. WSS results for the phantom showed the main features expected from fluid dynamics, notably the low values in the bulb region of the internal carotid artery, with a return to ordered flow further downstream. MRI was not able to detect the high WSS values along the divider wall that were predicted by the CFD model. Otherwise, there was good general agreement between MRI and CFD.ConclusionThis is the first report of time‐resolved WSS vectors estimated from 3D‐MRI data. The technique worked well except in regions of disturbed flow, where the combination with CFD modeling is clearly advantageous. J. Magn. Reson. Imaging 2003;17:153–162. © 2003 Wiley‐Liss, Inc.