bluuebunny/crossref_metadata_2025 huggingface dataset:
Evidence for a direct link between stress and immunity in the mollusc Haliotis tuberculata
Authors: Malham Shelagh K. , Lacoste Arnaud , Gélébart Florence , Cueff Anne , Poulet Serge A.
Published: January 2003

Stress is thought to cause increased disease outbreaks and mortality in a number of invertebrates but currently very little information is available on mechanisms linking physiological states of stress and reduced disease resistance in these organisms. In the present study, we examined the possibility that stress alters immune functions, the principal line of defense against pathogens, in a molluscan model, the abalone Haliotis turbeculata. Immune parameters were investigated in abalones subjected to a 15 min mechanical disturbance which, as indicated by noradrenaline and dopamine hemolymphatic levels, resulted in a transient state of physiological stress. During the application of the stressor, immune parameters such as the number of circulating hemocytes, the migratory activity, the phagocytic capacity and the respiratory burst responses of hemocytes, decreased significantly. All parameters returned to initial values within 15–30 min after the end of the disturbance and a transient period of immunostimulation occurred between 100 and 480 min after the stress for all immune parameters except intracellular superoxide anion production. These results indicate that in the abalone H. tuberculata, as in vertebrates, a link exists between stress and the immune system. This may begin to answer why stress and disease outbreaks are linked in shellfish. J. Exp. Zool. 295A:136–144, 2003. © 2003 Wiley‐Liss, Inc.
Iron uptake by hepatopancreas brush border membrane vesicles (BBMV) of the lobster (Homarus americanus)
Authors: Aslamkhan Amy G. , Ahearn Gregory A.
Published: January 2003

The uptake of 55Fe2+ and solubilized 55Fe3+ into brush border membrane vesicles prepared from the hepatopancreas of the Atlantic lobster (Homarus americanus) was investigated. Non‐specific surface binding of 55Fe2+ at equilibrium to the vesicular surface approximated 57% of total 55Fe2+ uptake. 55Fe2+ uptake showed temperature sensitivity and was trans‐stimulated by a Ca2+ gradient (at 5mM) directed out. Equilibrated 59Fe2+ exchanged for both Cd2+ and cold Fe2+. The data obtained in this study are suggestive that at least a portion of ferrous iron absorption may occur by a divalent exchanger mechanism. J. Exp. Zool. 295A:145–150, 2003. © 2003 Wiley‐Liss, Inc.
Yolk testosterone varies with sex in eggs of the lizard, Anolis carolinensis
Authors: Lovern Matthew B. , Wade Juli
Published: January 2003

In the green anole (Anolis carolinensis), a lizard with genotypic sex determination, yolk testosterone (T) concentration is greater in male‐producing than female‐producing eggs at oviposition, but the source and potential effects were not clear from previous studies. If yolk T levels are also sex‐specific before eggs are laid, a period during which embryonic steroidogenesis is unlikely, it would strongly suggest that the difference in yolk T is maternally derived. We collected yolk samples from eggs shelling within the oviducts of anesthetized females, and then allowed these females to lay the eggs naturally. Eggs were incubated to hatching to determine sex morphologically, and yolk T concentrations were analyzed by radioimmunoassay. As is the case just after they are laid, yolk T is higher in male than female oviductal eggs. To our knowledge, this is the earliest sex difference reported for any yolk steroid. We suggest that maternally derived yolk T levels could influence sex by differentially affecting male‐ and female‐inducing sperm, because fertilization occurs after yolk deposition and ovulation, while the egg is in the oviduct. Our results, together with those of an increasing number of studies, suggest that a relationship between hormones and vertebrate sex determination may be more widespread than generally appreciated. J. Exp. Zool. 295A:206–210, 2003. © 2003 Wiley‐Liss, Inc.
Partial cloning and expression of the cyclin B gene in the ovary of the bullseye puffer (Sphoeroides annulatus)
Authors: Gutiérrez Jesús Neftalí , Duncan Neil John , Estañol Perla Verónica , García‐aguilar Noemí , García‐Gasca Alejandra
Published: January 2003

The bullseye puffer is a marine fish species with great potential for aquaculture in Mexico, and the understanding of its reproductive physiology at every level of biological organization is essential in order to succeed. Several molecules orchestrate the complex process of oocyte maturation and spawning. One of these molecules is cyclin B, which is the regulatory subunit of the maturation‐promoting factor. In this study, a fragment of the cyclin B gene was isolated from the ovary of the bullseye puffer using an RT‐PCR approach. The gene fragment was homologous to the cyclin B2 gene of other vertebrate species. Similar levels of cyclin B gene expression were detected in ovaries at different developmental stages, except for atretic ovaries from captive fish which did not spawn. However, cyclin B gene expression was maintained in captive fish treated with LHRH‐a to induce spawning, and appeared to be similar to the pattern observed in wild fish. It is possible that the reduced expression of cyclin B in atretic ovaries is the result of mRNA degradation during atresia. Alternatively, reduced gene expression could be a controlling factor in the process of oocyte reabsorption since cyclin B is required for final oocyte maturation and ovulation. J. Exp. Zool. 295A:211–216, 2003. © 2003 Wiley‐Liss, Inc.
Hox genes as synchronized temporal regulators: Implications for morphological innovation
Authors: Crawford Michael
Published: January 2003

In vertebrates, clusters of Hox genes express in a nested and hierarchical fashion to endow the embryo's segments with discrete identities. Later in development, members of the same gene family are employed again to pattern the limb, intestinal, and reproductive systems. A careful analysis of the morphologies of Hox mutant mice suggests that the genes provide qualitatively different cues during the specification of segments than they do during the development of more recently derived structures. In addition to the regulatory differences noted by others, the activity of Hox genes during specification of the vertebrate metameres in some recent deletion experiments is inconsistent with a role for them as strictly spatial determinants. On the contrary, the phenotypes observed are suggestive of a role for them as elements of a generic time‐keeping mechanism. By contrast, the specification of more recent evolutionary structures appears to be more spatial and gene‐specific. These differences in role and effect may suggest some simple mechanisms by which the Hox clusters operate, and rules by which gene networks can be diverted to create new structures over the course of evolution. Specific predictions and experiments are proposed. J. Exp. Zool. (Mol. Dev. Evol.) 295B:1–11, 2003. © 2003 Wiley‐Liss, Inc.
A comparison of parthenogenetic and sexual embryogenesis of the pea aphid Acyrthosiphon pisum (Hemiptera: Aphidoidea)
Authors: Miura Toru , Braendle Christian , Shingleton Alexander , Sisk Geoffroy , Kambhampati Srinivas , Stern David L.
Published: January 2003

Aphids exhibit divergent modes of embryogenesis during the sexual and asexual phases of the life cycle. To explore how a single genome can give rise to these alternative developmental modes, we have initiated embryological studies of the pea aphid, Acyrthosiphon pisum. Here we present a detailed description of parthenogenetic, viviparous embryonic development in the pea aphid. We compare and contrast development of the parthenogenetic embryo with that of the embryo resulting from sexual reproduction. The primary difference between the embryos is the scale on which development occurs: early parthenogenetic development occurs in a volume approximately three orders of magnitude smaller than the sexual egg, largely because of the apparent absence of yolk in the parthenogenetic egg. This results in a drastically different duration of syncytial energid cleavage and, presumably, patterning processes in the two embryos must act at scales that differ by orders of magnitude. The eggs also develop on time scales that differ approximately by an order of magnitude and the timing of the embryonic movements, collectively called blastokinesis, have temporally shifted relative to growth of the embryo. In addition, the endosymbiotic bacteria are transferred from mother to embryo in different ways in the two embryos. Finally, the function of the serosa has diverged greatly in the two embryos: in the sexual egg the serosa deposits a thick cuticle that protects the egg, whereas the serosa of the parthenogenetic embryo is greatly reduced and its function is unclear. The pea aphid is a useful model system for examining how a single genome has evolved to allow divergent modes of development. J. Exp. Zool. (Mol. Dev. Evol.) 295B:59–81, 2003. © 2003 Wiley‐Liss, Inc.
Positive Darwinian selection operating on the immunoglobulin heavy chain of Antarctic fishes
Authors: Ota Tatsuya , Nguyen Thuy‐Ai , Huang Eric , Detrich H. William , Amemiya Chris T.
Published: January 2003

The cooling of the Southern Ocean to the freezing point of seawater (−1.9°C) over the past 25 million years played a dominant selective role in the evolution of the Antarctic fish fauna. During this period, the perciform suborder Notothenioidei, which is largely endemic to the Antarctic, diversified and developed numerous cold‐adapted characters. In this report, we provide compelling evidence that the immunoglobulin heavy chain (IgH) of the notothenioid fishes has undergone adaptive selection. Two and four IgH clones were isolated, respectively, from spleen cDNA libraries prepared from the Antarctic icefish Chaenocephalus aceratus and the yellowbelly rockcod Notothenia coriiceps. The transmembrane region of the membrane form of the rockcod IgM heavy chain was located at the end of the second constant (CH) domain, in contrast to other teleost IgMs in which the transmembrane region is located at the end of the third constant domain. Phylogenetic analyses of CH regions revealed that rates of nonsynonymous nucleotide substitution were higher than rates of synonymous nucleotide substitution. Many of the nonsynonymous substitutions introduced charge changes, consistent with positive Darwinian selection acting to adapt the structure of the notothenioid immunoglobulins. The rates of nonsynonymous nucleotide substitutions were higher than the rates of synonymous nucleotide substitutions in complementarity determining regions of variable regions, suggesting that diversity at antigen binding sites is enhanced by genomic and/or somatic selection. Results of Southern blot hybridization experiments were consistent with a translocon type of IgH gene organization reminiscent of bony fishes and tetrapods. J. Exp. Zool. (Mol. Dev. Evol.) 295B:45–58, 2003. © 2003 Wiley‐Liss, Inc.
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

The 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

Beta‐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

Chromosome 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

Evart 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

This 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

From 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

This 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

The 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

Bovine 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

Purpose

To 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 Methods

Fluoroptic 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.

Results

The 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.

Conclusion

The 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

Purpose

To explore the possibilities of combining multispectral magnetic resonance (MR) images of different patients within one data matrix.

Materials and Methods

Principal 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.

Results

Similar 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.

Conclusion

The 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

Purpose

To 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 Methods

Magnetic 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.

Results

The 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).

Conclusion

The 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

Purpose

To 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 Methods

A 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.

Results

Using 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.

Conclusion

The 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

Purpose

To 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 Methods

We 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.

Results

Examination 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.

Conclusion

A 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

Purpose

To prove the hypothesis that T1‐weighted (T1W) thermal mapping is reliable and achievable in magnetic resonance (MR)‐guided laser tumor ablation.

Materials and Methods

Near 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).

Results

Thermal 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).

Conclusion

In 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

Purpose

To study pulsatile fluid flow in a physiologically realistic model of the human carotid bifurcation, and to derive wall shear stress (WSS) vectors.

Materials and Methods

WSS 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.

Results

The 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.

Conclusion

This 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.
Serial, noninvasive, in vivo magnetic resonance microscopy detects the development of atherosclerosis in apolipoprotein E‐deficient mice and its progression by arterial wall remodeling
Authors: Choudhury Robin P. , Fayad Zahi A. , Aguinaldo J. Gilberto , Itskovich Vitalii V. , Rong James X. , Fallon John T. , Fisher Edward A.
Published: January 2003

Purpose

To test the ability of serial, in vivo magnetic resonance microscopy (MRM) to detect the development of atherosclerosis and quantify its progression in apolipoprotein E‐deficient mice.

Materials and Methods

The abdominal aortae of six ApoE−/− and three wild‐type (WT) control mice were imaged by MRM at 9.4T. Proton density weighted images were obtained (TR = 2000, TE = 9 msec) using four signal averages. The image resolution was 109 × 109 × 500 μm3. The six ApoE−/− mice underwent serial MRM three to five times over a period ≤ 44 weeks. Multiple, anatomically aligned MRM slices (N = 6–11 per time point, total 202) were compared serially in each animal.

Results

The abdominal aorta remained free of atherosclerosis until 20 weeks of age but thereafter, atherosclerosis was identified in all ApoE−/− mice (P < 0.05 to P < 0.001), but no WT controls. Lesion progression was accompanied by positive remodeling in which atherosclerosis within the aortic wall was accommodated by an increase in total cross sectional area (P < 0.01), while lumen area was unchanged.

Conclusion

Serial MRM demonstrated the development and progression of atherosclerosis in mouse aorta. Importantly, progression of atherosclerosis could be identified within individual animals. By following the same aortic lesions over time, MRM demonstrated that progression of atherosclerosis in mice is associated with positive arterial remodeling. J. Magn. Reson. Imaging 2003;17:184–189. © 2003 Wiley‐Liss, Inc.
MR imaging of the thyroid: Correlation between apparent diffusion coefficient and thyroid gland scintigraphy
Authors: Tezuka Mikio , Murata Yuji , Ishida Ryuji , Ohashi Isamu , Hirata Yukio , Shibuya Hitoshi
Published: January 2003

Purpose

To evaluate the usefulness of echo‐planar MR imaging for assessing the thyroid function and confirm the clinical use of MR imaging for thyroid diseases.

Materials and Methods

Thirty‐four patients with a variety of thyroid disorders (24 Graves disease; five subacute thyroiditis; five Hashimoto thyroiditis) were examined using T1‐, T2‐, and diffusion‐weighted magnetic resonance (MR) imaging and thyroid scintigraphy with Tc‐99m pertechnetate.

Results

The ADC values obtained from the diffusion‐weighted images of the patients with Graves disease were significantly higher than those of patients with subacute hyroiditis and Hashimoto thyroiditis, though no difference among those disorders was observed on T1‐ and T2‐weighted images. Based on the ADC value, anisotropy was not observed in the thyroid gland. An ADC value of 1.82 × 10−3 mm2/second or higher indicated the presence of Graves disease (sensitivity 75%, specificity 80%).

Conclusion

Diffusion‐weighted MR images may be of value for the diagnosis of thyroid diseases and could be clinically important in the evaluation of thyroid function. J. Magn. Reson. Imaging 2003;17:163–169. © 2003 Wiley‐Liss, Inc.
MRI of the liver: Can true FISP replace HASTE?
Authors: Herborn Christoph U. , Vogt Florian , Lauenstein Thomas C. , Goyen Mathias , Debatin Jörg F. , Ruehm Stephan G.
Published: January 2003

Purpose

To determine the diagnostic accuracy of two fast breath‐hold magnetic resonance (MR) imaging sequences, half‐Fourier acquired single turbo spin‐echo (HASTE) and true fast imaging with steady state precession (TrueFISP), for the detection and characterization of focal liver lesions

Materials and Methods

A total of 186 patients with suspected focal liver lesions were enrolled in this study. All patients underwent the same standardized study protocol including HASTE and TrueFISP. A consensus reading based on all available image data served as a standard of reference for classifying lesions into cysts, hemangiomas, focal nodular hyperplasia, or malignant/other lesions. All malignant lesions, as well as hepatic adenomas and abscesses, were histologically verified. Each separated by an eight‐week interval, HASTE and TrueFISP images were retrospectively reviewed in random order for the detection and characterization of focal hepatic lesions. Finally, a receiver operating characteristic (ROC) analysis was calculated.

Results

HASTE images had an overall sensitivity of 0.86 and a specificity of 0.91, whereas TrueFISP showed an overall sensitivity and specificity of 0.79 and 0.83, respectively (p>0.1).

Conclusion

Neither HASTE nor TrueFISP alone are sufficient for the detection and characterization of hepatic lesions. J. Magn. Reson. Imaging 2003;17:190–196. © 2003 Wiley‐Liss, Inc.
Percutaneous MR‐guided discography in a low‐field system using optical instrument tracking: A feasibility study
Authors: Sequeiros Roberto Blanco , Klemola Rauli , Ojala Risto , Jyrkinen Lasse , Vaara Teuvo , Tervonen Osmo
Published: January 2003

Purpose

To evaluate the feasibility of MRI‐guided discography with optical tracking.

Material and Methods

12 consecutive patients who had a clinical suspicion of lumbar discogenic pain and/or suggestive finding of disc degeneration in imaging studies (MRI, CT, plain radiography) underwent MRI‐guided discography in order to determine possible pain provocation during puncture and contrast injection. An 0.23 T open configuration MRI device with interventional tools (Outlook Proview, Philips Medical Systems, MR Technologies, Finland) was used in procedural imaging and instrument guidance. An optical guidance tool was attached to the MRI compatible needle (Chiba‐type MReye, Cook, Bloomington, IN). After initial disc puncture, 1–2 mL of gadolinium contrast (Magnevist, 469 mg/mL, Schering AG, Germany) saline mixture (1:8) was injected into the disc. Immediately after injection, sagittal FE T1 weighted images were obtained to verify the final position of the needle and formation of the MRI discogram. On nine patients, additional noncontrast sagittal fast spin echo (FSE) T1, FSE T2, and axial 3D T1 gradient echo imaging was performed before and after contrast media injection to obtain MRI discograms.

Results

Overall, 35 disc punctures were initialized and 34 MRI discograms were obtained. In all punctures, a positive or negative pain response was obtained. The average time for performing a procedure for three discs was 1 hour 25 minutes (minimum 45 minutes, maximum 2 hours, 15 minutes), and the average number of imaging sequences used for a puncturing one disc was 12. On one disc, the puncture failed and a discogram was not acquired. There was one complication (disc collapse) reported during follow‐up.Conclusion: Our results show that MRI guidance in performing discography is accurate and relatively safe. It is a technically comparable method to CT‐guidance or fluoroscopy. J. Magn. Reson. Imaging 2003;17:214–219. © 2003 Wiley‐Liss, Inc.
Coronary MR angiography: Respiratory motion correction with BACSPIN
Authors: Hardy Christopher J. , Zhao Lei , Zong Xuli , Saranathan Manojkumar , Yucel E. Kent
Published: January 2003

Purpose

To improve the signal‐to‐noise ratio (SNR) of breath‐held coronary magnetic resonance angiography (CMRA) without increasing the number or duration of breath holds.

Materials and Methods

In this BACSPIN (Breathing AutoCorrection with SPiral INterleaves) technique, a single breath‐held electrocardiogram (ECG)‐gated multi‐slice interleaved‐spiral data set is acquired, followed by repeated imaging of the same slices during free breathing. Each spiral interleaf from the breath‐held data set is used as a standard for comparison with corresponding acquisitions at the same interleaf angle during free breathing. The most closely matched acquisitions are incorporated into a multi‐slice, multi‐average data set with increasing SNR over time. In‐plane translations of the coronary artery can be measured and compensated for each accepted acquisition before combination with the other acquisitions.

Results

CMRA was performed on six volunteers, with improved SNR and minimal motional blurring. In some cases, breath holding could be dispensed with completely and the average respiratory position used as a reference.

Conclusion

BACSPIN provides a promising method for CMRA with improved SNR and limited breath‐holding requirements. J. Magn. Reson. Imaging 2003;17:170–176. © 2003 Wiley‐Liss, Inc.
Efficacy of passive acoustic screening: Implications for the design of imager and MR‐suite
Authors: Moelker Adriaan , Vogel Mika W. , Pattynama Peter M. T.
Published: January 2003

Purpose

To investigate the efficacy of passive acoustic screening in the magnetic resonance (MR) environment by reducing direct and indirect MR‐related acoustic noise, both from the patient's and health worker's perspective.

Materials and Methods

Direct acoustic noise refers to sound originating from the inner and outer shrouds of the MR imager, and indirect noise to acoustic reflections from the walls of the MR suite. Sound measurements were obtained inside the magnet bore (patient position) and at the entrance of the MR imager (health worker position). Inner and outer shrouds and walls were lined with thick layers of sound insulation to eliminate the direct and indirect acoustic pathways. Sound pressure levels (SPLs) and octave band frequencies were acquired during various MR imaging sequences at 1.5 T.

Results

Inside the magnet bore, direct acoustic noise radiating from the inner shroud was most relevant, with substantial reductions of up to 18.8 dB when using passive screening of the magnetic bore. At the magnet bore entrance, blocking acoustic noise from the outer shroud and reflections showed significant reductions of 4.5 and 2.8 dB, respectively, and 9.4 dB when simultaneously applied. Inner shroud coverage contributed minimally to the overall SPL reduction.

Conclusion

Maximum noise reduction by passive acoustic screening can be achieved by reducing direct sound conduction through the inner and outer shrouds. Additional measures to optimize the acoustic properties of the MR suite have only little effect. J. Magn. Reson. Imaging 2003;17:270–275. © 2003 Wiley‐Liss, Inc.
In vivo and in vitro MR spectroscopic profile of central neurocytomas
Authors: Jayasundar Rama , Shah Tariq , Vaishya Sandeep , Singh Virender P. , Sarkar Chitra
Published: January 2003

This study reports in vivo and in vitro magnetic resonance spectroscopic findings in two cases of central neurocytomas (CNC) confirmed by immunohistochemistry. Volume localized in vivo proton magnetic resonance spectroscopy (MRS) was carried out before surgery using a point resolved spectroscopy (PRESS) sequence with a repetition time of six seconds and an echo time of 135 msec. Normal spectrum was obtained from gray matter from a volunteer for comparison. 1H and 31P in vitro MRS studies were carried out at 9.4 T on the extracts prepared from the surgically excised tumors. The in vivo spectra showed prominent glycine (Gly) and choline (Cho) and low N‐acetyl aspartate compared to the normal. The Gly peak was assigned using the in vitro studies. These studies showed that the major contribution to the Cho peak observed in vivo is from phosphocholine. A combination of the presence of NAA and an increased Gly in the proton MR spectrum could be a characteristic feature of CNCs, which are rare intraventricular tumors of neuronal origin. J. Magn. Reson. Imaging 2003;17:256–260. © 2003 Wiley‐Liss, Inc.
Precise 3D skeletal kinematics using fast phase contrast magnetic resonance imaging
Authors: Rebmann Andrea J. , Sheehan Frances T.
Published: January 2003

Purpose

To examine the precision of cine‐phase contrast (PC) magnetic resonance imaging (MRI) techniques as applied to the quantification of three‐dimensional knee joint kinematics.

Materials and Methods

The knee joints of eight healthy volunteers were studied using three different dynamic, PC MRI protocols: cine‐PC (one average), cine‐PC (two averages), and cine‐PC with segmented phase encoding (fast‐PC).

Results

Fast‐PC has comparable precision, shorter scan times, and improved subject interexam variability (SIEV) compared to cine‐PC (two averages). Further, cine‐PC (one average) has low precision and high SIEV, making fast‐PC the preferred method of data acquisition. Specifically, the precision of fast‐PC MRI in measuring knee joint kinematics ranged from 0.22°–1.16°.

Conclusion

A cine‐PC MRI technique utilizing segmented phase encoding (fast‐PC MRI) acquires dynamic data at a faster rate than other PC imaging protocols, without compromising data precision. Being able to acquire precise 3D kinematics with shorter imaging times is critical if we are to use this technique to advance ongoing research in musculoskeletal kinematics. J. Magn. Reson. Imaging 2003;17:206–213. © 2003 Wiley‐Liss, Inc.