bluuebunny/crossref_metadata_2025 huggingface dataset:
Prox1 is a master control gene in the program specifying lymphatic endothelial cell fate
Authors: Hong Young‐Kwon , Harvey Natasha , Noh Yun‐Hee , Schacht Vivien , Hirakawa Satoshi , Detmar Michael , Oliver Guillermo
Published: November 2002

Early during development, one of the first indications that lymphangiogenesis has begun is the polarized expression of the homeobox gene Prox1 in a subpopulation of venous endothelial cells. It has been shown previously that Prox1 expression in the cardinal vein promotes and maintains the budding of endothelial cells that will form the lymphatic vascular system. Prox1‐deficient mice are devoid of lymphatic vasculature, and in these animals endothelial cells fail to acquire the lymphatic phenotype; instead, they remain as blood vascular endothelium. To investigate whether Prox1 is sufficient to induce a lymphatic fate in blood vascular endothelium, Prox1 cDNA was ectopically expressed by adenoviral gene transfer in primary human blood vascular endothelial cells and by transient plasmid cDNA transfection in immortalized microvascular endothelial cells. Transcriptional profiling combined with quantitative real‐time reverse transcription‐polymerase chain reaction and Western blotting analyses revealed that Prox1 expression up‐regulated the lymphatic endothelial cell markers podoplanin and vascular endothelial growth factor receptor‐3. Conversely, genes such as laminin, vascular endothelial growth factor‐C, neuropilin‐1, and intercellular adhesion molecule‐1, whose expression has been associated with the blood vascular endothelial cell phenotype, were down‐regulated. These results were confirmed by the use of specific antibodies against some of these markers in sections of embryonic and adult tissues. These findings validate our previous proposal that Prox1 is a key player in the molecular pathway leading to the formation of lymphatic vasculature and identify Prox1 as a master switch in the program specifying lymphatic endothelial cell fate. That a single gene product was sufficient to re‐program the blood vascular endothelium toward a lymphatic phenotype corroborates the close relationship between these two vascular systems and also suggests that during evolution, the lymphatic vasculature originated from the blood vasculature by the additional expression of only a few gene products such as Prox1. © 2002 Wiley‐Liss, Inc.
Evidence that nitric oxide regulates cell‐cycle progression in the developing chick neuroepithelium
Authors: Traister Alexandra , Abashidze Soulico , Gold Veronica , Plachta Nicolas , Karchovsky Esther , Patel Ketan , Weil Miguel
Published: November 2002

In all developing epithelia, the nuclei continually migrate between the apical and basal sides of the cell during the cell cycle, with S phase occurring basally and mitosis occurring apically. The purpose and mechanism of this nuclear migration are unknown. Here, we show that nitric oxide (NO) is endogenously produced in the developing chicken neural tube, where it apparently regulates cell‐cycle progression. We provide evidence that high NO levels promote entry into S phase basally, whereas low levels of NO facilitate entry into mitosis apically. © 2002 Wiley‐Liss, Inc.
Embryonic retinal gene expression in sonic‐you mutant zebrafish
Authors: Stenkamp Deborah L. , Frey Ruth A. , Mallory Dianne E. , Shupe Emily E.
Published: November 2002

Hedgehog (Hh) signaling is required for proper eye development in vertebrates; known roles for Hh in the zebrafish include regulation of eye morphogenesis, ganglion cell neurogenesis, and photoreceptor differentiation. To gain insight into the mechanisms by which Hh signaling influences these developmental events, we have examined proliferation, cell death, and expression patterns of several retinal genes in the eyes of embryonic zebrafish lacking the sonic hedgehog gene. We find that features of the eye phenotype of the sonic‐you (syu) mutant are consistent with multiple roles for the Hh signal during retinal development. Most interestingly, half of the mutant retinas failed to initiate cell differentiation and, instead, retained a neuroepithelial appearance. In the other half of the mutants, retinal cell differentiation was initiated, but not fully propagated. We also find that Hh signaling is important for retinal cell proliferation and retinal cell survival; together, these functions provide an explanation for progressive microphthalmia in the syu‐/‐ mutant. © 2002 Wiley‐Liss, Inc.
Expression of the ETS transcription factor ER81 in the developing chick and mouse hindbrain
Authors: Zhu Yan , Guthrie Sarah
Published: November 2002

ER81 is an ETS domain‐containing transcription factor, which is expressed in various developing tissues and organs of the embryo and in pools of developing spinal motor neurons and proprioceptive sensory neurons. Analysis of mice lacking ER81 function showed that this gene played an important role in the establishment of sensory‐motor circuitry in the spinal cord. Here, we investigate the expression pattern of er81 in the hindbrain of both chick and mouse embryos. We find that er81 is expressed in a subpopulation of inferior olive neurons, which send their projections to the caudal cerebellum. © 2002 Wiley‐Liss, Inc.
Prep2: Cloning and expression of a new prep family member
Authors: Haller Klaus , Rambaldi Isabel , Kovács Erzsébet Nagy , Daniels Eugene , Featherstone Mark
Published: November 2002

We describe Prep2, a new murine homeobox‐containing gene closely related to Prep1. The PREP2 protein belongs to the three amino acid loop extension (TALE) superclass of homeodomain‐containing proteins and encodes a polypeptide of 462 residues. As for PREP1, PREP2 binds an appropriate site on DNA as a heterodimer with PBX1A. Northern analysis, immunoblotting, immunohistochemistry, and in situ hybridization show widespread Prep2 expression during organogenesis and in the adult. The data suggest that Prep2 functions to varying degrees in a broad array of tissues and developmental processes. © 2002 Wiley‐Liss, Inc.
Tooth development is independent of a Hox patterning programme
Authors: James Chela T. , Ohazama Atsushi , Tucker Abigail S. , Sharpe Paul T.
Published: November 2002

Hox genes have a critical role in controlling the patterning processes of many tissues by imparting positional information in embryogenesis. Patterning of the pharyngeal component of the skull (the visceroskeleton) has been proposed to be influenced by this “Hox code.” Recently, it has been shown that Hox genes are associated with the evolution of jaws, loss of Hox gene expression in the first branchial arch being necessary for the transition from the agnathan condition to the gnathostome condition. Teeth develop on the first branchial arch in mammals and, therefore, might be expected to be under the control of Hox genes in a manner similar to that of the cranial skeletal elements. However, we show that, unlike cartilage and bone, the development of teeth is not affected by alterations in Hoxa2 expression. Tooth development in the first arch was unaffected by overexpression of Hoxa2, whereas recombinations of second arch mesenchyme with first arch epithelium led to tooth development within a Hoxa2‐positive environment. These data demonstrate that teeth develop from local interactions and that tooth formation is not under the axial patterning program specified by the Hox genes. We propose that the evolutionary development of teeth in the first branchial arch is independent of the loss of Hox expression necessary for the development of the jaw. © 2002 Wiley‐Liss, Inc.
Surface imaging microscopy, an automated method for visualizing whole embryo samples in three dimensions at high resolution
Authors: Ewald Andrew J. , Mcbride Helen , Reddington Mark , Fraser Scott E. , Kerschmann Russell
Published: November 2002

Modern biology is faced with the challenge of understanding the specification, generation, and maintenance of structures ranging from cells and tissues to organs and organisms. By acquiring images directly from the block face of an embedded sample, surface imaging microscopy (SIM) generates high‐resolution volumetric images of biological specimens across all of these scales. Surface imaging microscopy expands our range of imaging tools by generating three‐dimensional reconstructions of embryo samples at high resolution and high contrast. SIM image quality is not limited by depth or the optical properties of overlying tissue, and intrinsic or extrinsic alignment markers are not required for volume reconstruction. These volumes are highly isotropic, enabling them to be virtually sectioned in any direction without loss of image quality. Surface imaging microscopy provided a more accurate three‐dimensional representation of a chick embryo than confocal microscopy of the same sample. SIM offers excellent imaging of embryos from three major vertebrate systems in developmental biology: mouse, chicken, and frog. Immediate applications of this technology are in visualizing and understanding complex morphogenetic events and in making detailed comparisons between normal and genetically modified embryos. © 2002 Wiley‐Liss, Inc.
An amphioxus winged helix/forkhead gene,AmphiFoxD: Insights into vertebrate neural crest evolution
Authors: Yu Jr‐Kai , Holland Nicholas D. , Holland Linda Z.
Published: November 2002

During amphioxus development, the neural plate is bordered by cells expressing many genes with homologs involved in vertebrate neural crest induction. However, these amphioxus cells evidently lack additional genetic programs for the cell delaminations, migrations, and differentiations characterizing definitive vertebrate neural crest. We characterize an amphioxus winged helix/forkhead gene (AmphiFoxD) closely related to vertebrateFoxDgenes. Phylogenetic analysis indicates that theAmphiFoxDis basal to vertebrateFoxD1,FoxD2,FoxD3,FoxD4, andFoxD5. One of these vertebrate genes (FoxD3) consistently marks neural crest during development. Early in amphioxus development,AmphiFoxDis expressed medially in the anterior neural plate as well as in axial (notochordal) and paraxial mesoderm; later, the gene is expressed in the somites, notochord, cerebral vesicle (diencephalon), and hindgut endoderm. However, there is never any expression in cells bordering the neural plate. We speculate that anAmphiFoxDhomolog in the common ancestor of amphioxus and vertebrates was involved in histogenic processes in the mesoderm (evagination and delamination of the somites and notochord); then, in the early vertebrates, descendant paralogs of this gene began functioning in the presumptive neural crest bordering the neural plate to help make possible the delaminations and cell migrations that characterize definitive vertebrate neural crest. © 2002 Wiley‐Liss, Inc.
Ultrasonic imaging with narrow aperture phased array
Authors: Takizawa Naoki , Ohya Akihisa , Akiyama Iwaki
Published: November 2002

This paper describes the method of narrow aperture phased array ultrasonic computed tomography (NAPA‐CT), conceived for three‐dimensional imaging with increased resolution and speed in the field of clinical diagnosis. By reducing the size of the transducer in the thickness direction, a beam is formed such that the focal region of the phased array is a circular arc. This arc focus is scanned in a sector and is further rotated about the sound axis to acquire an echo. Then, the scatterer distribution on a hemisphere containing the arc as its part can be reconstructed by the inverse Radon transform. The feasibility of the proposed method is investigated by simulation and experiment. © 2002 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 86(2): 72–81, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.10029
Design of nonlinear adaptive digital filter by wavelet shrinkage
Authors: Tokairin Tomoya , Sato Yoshiharu
Published: November 2002

The wavelet shrinkage method is a nonlinear signal denoising procedure to remove noise by shrinking the empirical wavelet coefficients in the wavelet domain. In this paper, we apply the wavelet shrinkage method to nonlinear adaptive digital filters, and we propose the adaptive wavelet shrinkage filter which updates the threshold levels adaptively by the LMS algorithm according to the reference signal. The adaptive wavelet shrinkage filter is robust and has the property that one can control the filter easily by modifying the threshold levels. We describe the theorems concerning the convergence of the LMS algorithm for updating the threshold levels, and demonstrate several examples of the adaptive wavelet shrinkage filter. © 2002 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 86(2): 59–71, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.10032
A design technique for two‐dimensional FIR digital filters with noniterative numerical calculation
Authors: Tsuchiya Mamoru
Published: November 2002

A novel design algorithm is proposed for two‐dimensional linear‐phase FIR digital filter approximating constant amplitude over the entire passband. The design technique proposed in this paper is an analytical method in which the filter coefficients can be obtained with noniterative numerical calculation. This design technique is based on the idea that the specified filter characteristics of the filters to be realized can be made out using the frequency response of a one‐dimensional window function with well‐known characteristics. In this paper, we present a number of design examples to illustrate the flexibility and effectiveness of the proposed technique as a comprehensive design technique. © 2002 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 86(2): 43–58, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.10033
Direction‐of‐arrival estimation of speech using virtually generated multichannel data from two‐channel microphone array
Authors: Tanigawa Shinichi , Hamada Nozomu
Published: November 2002

Recently, with rapid progress in multimedia technologies, hopes for a speech‐based man‐machine interface have increased. For high‐quality voice collection and acquisition of the position information of the speaker, direction‐of‐arrival (DOA) estimation technology for voice with a microphone array has been discussed. However, one problem is large‐scale implementation of the arrays. In the present research, a new DOA estimation method for a two‐channel microphone array based on the harmonic structure of vowels is proposed. The present method has been applied in a real‐world environment and its effectiveness has been confirmed. © 2002 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 86(2): 33–42, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.10038
Generation of physical random numbers with a variable‐capacitor parametron
Authors: Saitoh Yoshiaki , Hori Junichi , Nishimura Hiroshi , Kiryu Tohru
Published: November 2002

In the present study, a random number generator which physically produces nonperiodic uniform random number was developed using the parametron principle. The parametron is an oscillation circuit at one‐half of the excited frequency. The phase of the parametron cannot be predicted because it depends on the noise in the parametron circuit. The random number was generated by detecting the unpredictable phase. The randomness of the data generated by the present method was confirmed by the spatial distribution and by statistical random tests. © 2002 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 86(2): 24–32, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.10040
Cooperative communication model: Human‐robot interface based on relationship with robot
Authors: Imai Michita , Ono Tetsuo , Nakatsu Ryouhei , Anzai Yuichiro
Published: November 2002

In conversations between two people, the listener understands the content spoken by the speaker even if the speech is hard to hear by relying on the intent of the speaker and the surroundings. In this paper, we explain the condition where the human starts to refer to the robot's intent and real‐world information in order to bring human‐robot communication closer to communication between humans. Specifically, we propose a communication model, a cooperative communication model, that focuses on the human‐robot relationship. We also conduct behavioral experiments using an actual robot to prove the validity of this model. In the experiment, we built a relationship with a human in a robot by using a computer graphics (CG) agent and examined the effect of the human‐robot relationship on the communication. We found from the experimental results that an interface that builds a relationship between a human and a robot is required in order for the intent and state of the robot to be referenced by the human. © 2002 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 86(2): 13–23, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.10052
Estimation of chaotic ordinary differential equations by coevolutional genetic programming
Authors: Ikeda Yoshikazu
Published: November 2002

This paper describes a method of estimation of ordinary differential dynamics by Genetic Programming (GP) and discusses the accuracy of estimation. The dynamics is expressed by a tree structure and we obtain a numerical solution by carrying out digital integration (Runge‐Kutta‐Gill method) of the function system. The square error of the numerical solution and the original data is calculated and the inverse of the error is used as an evaluation of the individuals (functions) of the GP. Genetic operations such as crossover and mutation are carried out on pairs of solution candidates with high evaluation values, and the solutions (functions) are optimized. In addition, a coevolutional model that can efficiently perform simultaneous estimation of multiple functions is proposed.

In the study of the estimation error, two systems, the Lorenz and Rössler systems, which are representatives of the chaotic ordinary differential model, are estimated and it is shown that a function of the same shape as the original one can be estimated in one‐function estimation, and that in multiple‐function (three‐function) estimation, the coevolutional model is effective. © 2002 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 86(2): 1–12, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.10057
Adaptive error diffusion using fuzzy reasoning for step edges
Authors: Muneyasu Mitsuji , Oda Tetsuya , Nakata Yoshihisa , Hinamoto Takao
Published: November 2002

When multivalued images are transformed to binary images, the error diffusion method is often used because it is excellent in gray scale representation. When the error diffusion method is applied by means of a raster scan, equal‐color regions with all black pixels or all white pixels occur along the edges. This phenomenon has the effect of emphasizing the edges, and the edges may be visually emphasized excessively. In this paper, in order to freely control the equal‐color regions, a method that adaptively adjusts the filter coefficients in the error diffusion method based only on the difference from the points to be processed is presented. The filter coefficients are computed by using fuzzy reasoning. According to the proposed method, the width of the equal‐color region near a step edge can be controlled adequately by providing appropriate values. © 2002 Wiley Periodicals, Inc. Electron Comm Jpn Pt 3, 86(2): 82–90, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecjc.1135
Bent but not broken: An introduction to the issue on chronic illness
Authors: Rainer Jackson P.
Published: November 2002

What is the difference between sackcloth and ashes and chronic illness? You can always take a shower and change shirts. © 2002 Wiley Periodicals, Inc. J Clin Psychol/In Session 58: 1347–1350, 2002.
Ambiguous loss from chronic physical illness: Clinical interventions with individuals, couples, and families
Authors: Boss Pauline , Couden Barbara A.
Published: November 2002

The theory of ambiguous loss is applied to chronic illness in individuals, couples, and families. Lack of clarity about prognosis, daily physical condition, and fluctuating capabilities create relationship confusion, preoccupation with the illness, or avoidance of the ill individual. Immobilization, depression, and relationship collapse may occur in response to features of chronic illness over which there is no control. A case study illustrates helpful therapeutic interventions for couples and families with chronically ill members. © 2002 Wiley Periodicals, Inc. J Clin Psychol/In Session 58: 1351–1360, 2002.
Mind's response to the body's betrayal: Gestalt/existential therapy for clients with chronic or life‐threatening illnesses
Authors: Imes Suzanne A. , Clance Pauline Rose , Gailis Andra T. , Atkeson Ellen
Published: November 2002

In the literature on chronic or life‐threatening illness, there is an overriding emphasis on clients' psychological coping styles and how they relate to psychological functioning. By contrast, in our approach, we look at the subjective mind/body experiences that clients have of their illness and how their lives are impacted by their illness. As psychotherapists, we address their existential distress, pain, body experience, thoughts, and feelings, as well as their efforts to cope or find meaning in their illness. We summarize Gestalt/Existential therapy for chronic illness, illustrate the approach with three case‐vignettes, and stress the importance of attending to each client's unique responses to illness. © 2002 Wiley Periodicals, Inc. J Clin Psychol/In Session 58: 1361–1373, 2002.
Chronic illness as a family process: A social‐developmental approach to promoting resilience
Authors: Shapiro Ester R.
Published: November 2002

This paper describes a social‐developmental approach to interventions in chronic illness using naturally occurring processes of change during family life‐cycle transitions to promote more positive developmental outcomes. Clinical interventions can help build resilience by creating a therapeutic collaboration designed to help patients improve their use of existing and new resources in multiple systems. They can then better meet demands of the illness as it impacts on shared development. A case example of a 13‐year‐old daughter with complex, chronic health problems and developmental disabilities illustrates clinical interventions designed to promote family resilience during the entry into adolescence and a transition in schooling. This approach involves focusing on the family's own definition of the current problem and relevant history, constructing a multidimensional, coherent story of the illness and its impact that recognizes stressors yet highlights strengths, and normalizing their strategies for stability under circumstances of developmental stress. These interventions with mother, daughter, and family helped improve health efficacy, communication toward mutual understanding and shared problem solving, and better use of existing and new resources to enhance current and future developmental adaptation. © 2002 Wiley Periodicals, Inc. J Clin Psychol/In Session 58: 1375–1384, 2002.
Chronic pain: Psychological approaches for the front‐line clinician
Authors: Arena John G.
Published: November 2002

Many of the techniques and skills the average front‐line practitioner possesses (such as intake, psychological testing, cognitive behavior therapy, and relaxation therapy) can be readily and effectively applied to a chronic‐pain population. More specialized techniques for pain reduction, such as biofeedback training, can be easily learned by the generalist clinician with a minimum of additional training. In this article, four general steps to assess and reduce chronic pain are reviewed. Through careful use of the available research literature, and by consulting with a colleague who has expertise in chronic pain, most psychologists can straightforwardly begin to help individuals suffering from chronic pain. © 2002 Wiley Periodicals, Inc. J Clin Psychol/In Session 58: 1385–1396, 2002.
Beyond a sense of safety: A psychologist's tale of serious chronic illness
Authors: Sollod Robert N.
Published: November 2002

Based on a narrative account, this paper highlights and reviews the experiences of the author, a psychologist, experiencing a chronic illness. Areas covered include coping with doctors and medical personnel, adjusting to illness, complying, actively coping, and even, at times, resisting unwarranted medical procedures. Experiences such as loss of trust, a sense of isolation, re‐working relationships, and generative reaching‐out are also covered. Some positive consequences of chronic illness for personal growth are suggested. Suggestions for conducting psychotherapy with clients who are dealing with serious chronic illness are made. © 2002 Wiley Periodicals, Inc. J Clin Psychol/In Session 58: 1397–1409, 2002.
Pushing through solid rock: Words of wisdom for clinicians from four patients with life‐threatening conditions
Authors: Zucker Robert
Published: November 2002

Four subjects living with profoundly debilitating and life‐threatening illnesses reflect on how psychotherapy has contributed to their ability to cope and survive. With frankness and eloquence they address issues related to cancer, heart disease, fibromyalgia, and AIDS. © 2002 Wiley Periodicals, Inc. J Clin Psychol/In Session 58: 1411–1420, 2002.
Caregiving at the end of life
Authors: Rainer Jackson P. , McMurry Patti Ellis
Published: November 2002

Meeting the demands of chronic illness and disease states is challenging, at best. Too often, the chronicity of the illness hastens death. The physical, psychological, and sociological changes that accompany the death of an individual require attention and forethought if the life transition is to be made with elegance and grace. This article addresses the caregiving demands for the professional and familial/social support surrounding the chronically ill individual at the end of life. Focus is placed on the preparation of advance directives—legal documents that set clear boundaries for honoring the wishes of the patient. © 2002 Wiley Periodicals, Inc. J Clin Psychol/In Session 58: 1421–1431, 2002.
Compassion fatigue: Psychotherapists' chronic lack of self care
Authors: Figley Charles R.
Published: November 2002

Psychotherapists who work with the chronic illness tend to disregard their own self‐care needs when focusing on the needs of clients. The article discusses the concept ofcompassion fatigue, a form of caregiver burnout among psychotherapists and contrasts it with simple burnout and countertransference. It includes a multi‐factor model of compassion fatigue that emphasizes the costs of caring, empathy, and emotional investment in helping the suffering. The model suggests that psychotherapists that limiting compassion stress, dealing with traumatic memories, and more effectively managing case loads are effective ways of avoiding compassion fatigue. The model also suggests that, to limit compassion stress, psychotherapists with chronic illness need to development methods for both enhancing satisfaction and learning to separate from the work emotionally and physically in order to feel renewed. A case study illustrates how to help someone with compassion fatigue. © 2002 Wiley Periodicals, Inc. J Clin Psychol/In Session 58: 1433–1441, 2002.
Inside every chronic patient is an acute patient wondering what happened
Authors: Brown, F. Marcus
Published: November 2002

This In Session describes how chronic illness erodes connections, eludes definition, and reduces one's ability to manage daily life. The contributors compassionately and competently provide an array of perspectives, pragmatic techniques, and caveats. This concluding article seeks to integrate the articles in this issue and to deepen the clinician's ability to meet the needs of a chronically ill individual requesting psychotherapy. Particular emphasis is given to three models of psychotherapy with chronically ill individuals, care giving at the end of life, and compassion fatigue found in professionals working with this population. Multiple case examples are provided to illustrate psychotherapy and psychosocial intervention strategies. © 2002 Wiley Periodicals, Inc. J Clin Psychol/In Session 58: 1443–1449, 2002.
Functional imaging of the rat cervical spinal cord
Authors: Malisza Krisztina L. , Stroman Patrick W.
Published: November 2002

Purpose:

To examine functional magnetic resonance imaging (fMRI) of the rat cervical spinal cord using painful stimulation.

Materials and Methods:

fMRI of the rat cervical spinal cord was performed at 9.4 T. Stimuli included injection of 25μL of capsaicin (128 μg/mL in 7.5% dimethylsulfoxide (DMSO)) into the right dorsal forepaw and electrical stimulation (15 V, 0.3 msec, 3 Hz) of the left dorsal forepaw.

Results:

Activation in the dorsal horn of the spinal cord, which is known to be associated with the transmission of pain, was found in all rats (N = 4) following injection of capsaicin into the dorsal forepaw. It was possible to reproduce the pain response in a given animal several times throughout the course of an experiment, provided that sufficient time was allowed between capsaicin injections. Regions of the spinal cord associated with motor and pain response were observed in functional imaging experiments involving subcutaneous electrical stimulation of the dorsal forepaw.

Conclusion:

Spinal fMRI using electrical stimulation and capsaicin‐induced painful stimulation can be a useful tool in an animal model of pain and injury. J. Magn. Reson. Imaging 2002;16:553–558. © 2002 Wiley‐Liss, Inc.
Acoustic noise and functional magnetic resonance imaging: Current strategies and future prospects
Authors: Amaro Edson , Williams Steve C.R. , Shergill Sukhi S. , Fu Cynthia H.Y. , MacSweeney Mairead , Picchioni Marco M. , Brammer Michael J. , McGuire Philip K.
Published: November 2002

Functional magnetic resonance imaging (fMRI) has become the method of choice for studying the neural correlates of cognitive tasks. Nevertheless, the scanner produces acoustic noise during the image acquisition process, which is a problem in the study of auditory pathway and language generally. The scanner acoustic noise not only produces activation in brain regions involved in auditory processing, but also interferes with the stimulus presentation. Several strategies can be used to address this problem, including modifications of hardware and software. Although reduction of the source of the acoustic noise would be ideal, substantial hardware modifications to the current base of installed MRI systems would be required. Therefore, the most common strategy employed to minimize the problem involves software modifications. In this work we consider three main types of acquisitions: compressed, partially silent, and silent. For each implementation, paradigms using block and event‐related designs are assessed. We also provide new data, using a silent event‐related (SER) design, which demonstrate higher blood oxygen level‐dependent (BOLD) response to a simple auditory cue when compared to a conventional image acquisition. J. Magn. Reson. Imaging 2002;16:497–510. © 2002 Wiley‐Liss, Inc.
Correction for displacement artifacts in 3D phase contrast imaging
Authors: Thunberg Per , Wigström Lars , Ebbers Tino , Karlsson Matts
Published: November 2002

Purpose

To correct for displacement artifacts in 3D phase contrast imaging.

Materials and Methods

A 3D phase contrast pulse sequence was modified so that displacements of velocity measurements were restricted to one direction. By applying a postprocessing method, displaced measurements could be traced back to their accurate positions. Flow studies were performed using a phantom that generated flow through a stenosis, directed oblique relative to the phase and frequency encoding directions. Velocity profiles and streamline visualization were used to compare displaced and corrected velocity data to a reference.

Results

Velocity profiles obtained from the original measurement showed skewed profiles due to the displacement artifact, both at close proximity to the orifice as well as further downstream. After correction, concordance with the reference improved considerably.

Conclusion

The displacement artifact, which restricts the accuracy of phase contrast measurements, can be corrected for using the proposed method. Correction of the phase contrast velocity data may improve the accuracy of subsequent flow analysis and visualization. J. Magn. Reson. Imaging 2002;16:591–597. © 2002 Wiley‐Liss, Inc.
MR assessment of cerebral vascular response: A comparison of two methods
Authors: Spilt Aart , Van den Boom Rivka , Kamper Adriaan M. , Blauw Gerard J. , Bollen Edward L.E.M. , van Buchem Mark A.
Published: November 2002

Purpose

To compare the results and reproducibility of two MR‐based methods of measuring the cerebrovascular response (CVR).

Materials and Methods

In eight volunteers, CVR was assessed with two MR‐based methods upon a challenge with acetazolamide. CVR was assessed by measuring changes in total cerebral blood flow (TCBF) using phase contrast (PC) MRI, and by measuring perfusion MRI. To assess reproducibility the measurements were repeated after 1 week.

Results

The average CVR with the PC‐MRI method was 46% (SD = 16%), and for perfusion MR the measured CVR was 44% (SD = 16%). The coefficient of variation (COV) for PC‐MRI was 28%, while perfusion MR had a COV of 26%. The limits of agreement between the two methods were −49% and 45%, demonstrating a lack of agreement between the two methods in terms of CVR estimation.

Conclusion

CVR estimates based on PC‐MRI and perfusion MRI showed reproducibility but a lack of agreement in healthy volunteers. This lack of agreement can be attributed to the different aspects of the CVR reflected by these methods: TCBF reflects changes in CBF, whereas our perfusion MRI method reflects cerebral blood volume (CBV). J. Magn. Reson. Imaging 2002;16:610–616. © 2002 Wiley‐Liss, Inc.
Single‐voxel long TE 1H‐MR spectroscopy of the normal brainstem and cerebellum
Authors: Mascalchi Mario , Brugnoli Roberto , Guerrini Laura , Belli Giacomo , Nistri Marco , Politi Letterio S. , Gavazzi Cinzia , Lolli Francesco , Argenti Giovanni , Villari Natale
Published: November 2002

Purpose:

To evaluate the feasibility of single voxel 1H‐MRS of the CNS structures contained in the posterior cranial fossa and to determine the distribution of the normal metabolite ratios, concentrations, and T2 relaxation times in the midbrain, pons, medulla, dentate nucleus and cerebellar vermis.

Materials and Methods:

A total of 147 single voxel 1H‐MR spectra with a point‐resolved proton spectroscopy sequence (PRESS) sequence and echo time (TE) of 136 or 272 msec were obtained in the midbrain, pons, medulla, dentate, and vermis of 31 healthy volunteers. In seven additional patients; the concentrations and T2 relaxation times of metabolites were obtained in the same locations (except the medulla) with an external phantom calibration method and a four TE PRESS technique.

Results:

Ten (27%) of 36 spectra acquired in the medulla were of poor quality. A similar ranking of the N‐acetyl aspartate (NAA)/creatine (Cr) ratio and choline(Cho)/Cr ratios in the five locations for the two TEs was observed, with the highest values in the pons (mean NAA/Cr = 4.16 ± 0.6 and Cho/Cr =2.66 ± 0.6 at TE 272) and the lowest values in the dentate and vermis (mean NAA/Cr = 1.66 ± 0.2 and Cho/Cr = 1.20 ± 0.2 at TE 272). The analysis of variance showed significant regional differences of the NAA and Cr concentrations, which had the highest values in the dentate. Non‐significant regional differences were observed for the concentration of Cho and for the T2 of the metabolites.

Conclusion:

With the exception of the medulla, single voxel 1H‐MRS enables an in vivo biochemical analysis of the CNS structures contained in the posterior cranial fossa. Regional differences in the metabolite ratios and concentrations must be considered when employing 1H‐MRS for evaluation of diseases of the brainstem and cerebellum. J. Magn. Reson. Imaging 2002;16:532–537. © 2002 Wiley‐Liss, Inc.
Proton magnetic resonance spectroscopy with metabolite nulling reveals regional differences of macromolecules in normal human brain
Authors: Mader Irina , Seeger Uwe , Karitzky Jochen , Erb Michael , Schick Fritz , Klose Uwe
Published: November 2002

Purpose

To quantify the macromolecular content in different anatomic brain regions and to evaluate an age dependency of the macromolecular concentrations.

Material and Methods

A short echo time Stimulated Echo Acquisition Mode (STEAM) sequence was used without and with inversion recovery metabolite nulling in 8–12 healthy volunteers. Quantitation was achieved by an extended LCModel, and macromolecular resonances at 0.9, 1.4, 2.1, and 3.0 ppm were evaluated.

Results

In the cerebellum, the 1.4, 2.1, and 3.0 ppm resonances were highest compared to all other regions (P < 0.02); the 0.9 ppm resonance was significantly higher than that of pons (P < 0.01). In the motor cortex, the 0.9, 1.4, and 2.1 ppm resonances were higher than those of white matter and pons (P < 0.02). Pons and white matter did not differ significantly from each other. A significant correlation of the macromolecular concentrations with the age could not be found.

Conclusion

There were higher macromolecular concentrations in the cerebellum and motor cortex than in pons or white matter. These were probably due to the higher portions of gray matter in these volumes of interest (VOIs) than in the other regions. J. Magn. Reson. Imaging 2002;16:538–546. © 2002 Wiley‐Liss, Inc.
Multiplanar MR temperature‐sensitive imaging of cerebral thermal treatment using interstitial ultrasound applicators in a canine model
Authors: Kangasniemi Marko , Diederich Chris J. , Price DVM Roger E. , Stafford R. Jason , Schomer Donald F. , Olsson Lars E. , Tyreus Per Daniel , Nau Will H. , Hazle John D.
Published: November 2002

Purpose

To study the feasibility of an interleaved gradient‐echo, echo‐planar imaging (iGE‐EPI) sequence for multiplanar magnetic resonance temperature imaging (MRTI) to monitor intracerebral thermal treatment three‐dimensionally using multielement ultrasound applicators.

Materials and Methods

Transmissible venereal tumor (TVT) fragments were injected into the right cerebral hemisphere of five dogs. Guided by MRI, an interstitial ultrasound applicator was inserted into the tumor or normal brain tissue. The iGE‐EPI sequence was used to estimate temperature changes by computing the complex phase‐difference induced by temperature‐dependent shifts in the proton resonance frequency of water. The thermal dose maps were updated every 6–8 seconds for five to seven image planes during treatment. The results of MRTI were compared with those of post‐treatment MRI and histologic analysis.

Results

The multiplanar MRTI monitored temperature and thermal dose distributions in tumor and normal brain tissue over the entire user‐defined treatment volume. The ultrasound applicators produced contiguous areas of coagulative necrosis, resulting in 1.5–4.0 cm3 volumes of tissue necrosis. MRTI‐based assessments of thermal‐dose distributions were consistent with the results of post‐treatment MRI and histologic analysis.

Conclusion

Multiplanar MRTI is feasible for measuring necrosing thermal doses during intracerebral thermal delivery by interstitial ultrasound applicators. J. Magn. Reson. Imaging 2002;16:522–531. © 2002 Wiley‐Liss, Inc.
Changes in oxygenation of intracranial tumors with carbogen: A BOLD MRI and EPR oximetry study
Authors: Dunn Jeff F. , O'Hara Julia A. , Zaim‐Wadghiri Youssef , Lei Hao , Meyerand M. Elizabeth , Grinberg Oleg Y. , Hou Huagang , Hoopes P. Jack , Demidenko Eugene , Swartz Harold M.
Published: November 2002

Purpose

To examine, using blood oxygen level dependent (BOLD) MRI and EPR oximetry, the changes in oxygenation of intracranial tumors induced by carbogen breathing.

Materials and Methods

The 9L and CNS‐1 intracranial rat tumor models were imaged at 7T, before and during carbogen breathing, using a multi‐echo gradient‐echo (GE) sequence to map R2*. On a different group of 9L tumors, tissue pO2 was measured using EPR oximetry with lithium phthalocyanine as the oxygen‐sensitive material.

Results

The average decline in R2* with carbogen breathing was 13 ± 1 s−1 in the CNS‐1 tumors and 29 ± 4 s−1 in the 9L tumor. The SI vs. TE decay curves indicate the presence of multiple components in the tumor. Tissue pO2 in the two 9L tumors measured was 8.6 ± 0.5 and 3.6 ± 0.6 mmHg during air breathing, and rose to 20 ± 7 and 16 ± 4 mmHg (mean ± SE) with carbogen breathing. Significant changes were observed by 10 minutes, but changes in pO2 and R2* continued in some subjects over the entire 40 minutes.

Conclusion

EPR results indicate that glial sarcomas may be radiobiologically hypoxic. Both EPR and BOLD data indicate that carbogen breathing increases brain tumor oxygenation. These data support the use of BOLD imaging to monitor changes in oxygenation in brain tumors. J. Magn. Reson. Imaging 2002;16:511–521. © 2002 Wiley‐Liss, Inc.
Structure of the water resonance in small voxels in rat brain detected with high spectral and spatial resolution MRI
Authors: Fan Xiaobing , Du Weiliang , MacEneaney Peter , Zamora Marta , Karczmar Gregory
Published: November 2002

Purpose:

To acquire high spectral and spatial resolution (HiSS) MR images of the water resonance in rat brain, evaluate the lineshape of the water resonance in small voxels, and compare images derived from HiSS data with conventional images.

Materials and Methods:

Spectroscopic images of rat brain were obtained at 4.7 Tesla using phase encoding gradients only. Spectral resolution in each voxel was ∼8 Hz and bandwidth was 1000 Hz. Spatial resolution was ∼250 microns in 1‐mm slices. Images were synthesized to show the water signal integral, peak height, linewidth, resonance frequency, and asymmetry.

Results:

Two or more resolved components of the water resonance were detected in ∼14% ± 6% of voxels in the brains of eight rats. The water resonances in ∼20% ± 10% of voxels (n = 8) were highly asymmetric. Images with intensity proportional to water signal peak height, T2*, or to selected components of the water resonance showed features that were not evident in conventional images.

Conclusions:

The complexity of the water signal reflects the anatomy and physiology of the sub‐voxelar environment, and may be a useful source of image contrast. HiSS imaging of brain provides accurate anatomic information, and may improve image contrast and delineation of subtle anatomic features. J. Magn. Reson. Imaging 2002;16:547–552. © 2002 Wiley‐Liss, Inc.
Preoperative evaluation of patients awaiting liver transplantation: Comparison of multiphasic contrast‐enhanced 3D magnetic resonance to helical computed tomography examinations
Authors: Eubank William B. , Wherry Kimberly L. , Maki Jeff H. , Sahin Hakan , Funkhouser Charles P. , Schmiedl Udo P.
Published: November 2002

Purpose

To determine the feasibility of using a multiphasic magnetic resonance (MR) examination to evaluate the hepatic arterial anatomy and parenchyma in patients awaiting orthotopic liver transplantation (OLT).

Materials and Methods

Twenty consecutive patients awaiting OLT underwent multiphasic MR (using a T1‐weighted 3D gadolinium‐enhanced gradient‐echo (GRE) sequence and two separate injections of contrast material) and computed tomography (CT) imaging; both imaging studies were performed within a 1‐week period for each patient. Quantitative and qualitative assessment of the hepatic arterial system on MR data was performed. Two independent observers classified the hepatic arterial anatomy and evaluated the hepatic parenchyma from the MR data. The prospective CT interpretation was used as the gold standard.

Results

Overall qualitative rating of hepatic arterial system‐to‐background contrast on MR data was good to excellent (average pooled score of 2.00 ± 0.27), with no significant difference between the two observers after the first or second injections of contrast material. Classification of hepatic arterial anatomy by MR angiography (MRA) and CT angiography (CTA) was concordant in 85% (17/20) of patients and discordant in 15% (3/20) of patients. Focal parenchymal lesions were detected in 25% (5/20) of patients by MR and CT; however, two lesions in one patient with multiple lesions were detected only with MR.

Conclusion

Multiphasic T1‐weighted 3D gadolinium‐enhanced MR examination can provide comprehensive evaluation of the hepatic arterial anatomy and parenchyma in patients awaiting OLT. MR may offer an advantage over CT in the detection of focal parenchymal lesions. J. Magn. Reson. Imaging 2002;16:565–575. Published by Wiley‐Liss, Inc.
Combined high‐resolution and real‐time imaging: A technical feasibility study on coronary magnetic resonance angiography
Authors: Eggers Holger , Koken Peter , Manke Dirk , Boesiger Peter , Boernert Peter
Published: November 2002

Purpose

To propose a new approach to combining high‐resolution and real‐time imaging and to show its technical feasibility on the example of coronary magnetic resonance angiography.

Materials and Methods

The insertion of fast two‐dimensional (2D) acquisitions into time intervals that have not been utilized by triggered or gated 2D or three‐dimensional (3D) acquisitions so far is suggested, as well as the immediate reconstruction and display of the additional data. For a technical validation of this concept, a 2D ventricular function protocol was interleaved into a cardiac‐triggered and respiratory‐gated 3D coronary angiography protocol. Dedicated hardware was employed to rapidly process the data originating from the former. Since the sampling of the latter was restricted to intervals with minimal motion, remaining periods of time could be used to simultaneously image the cardiac and respiratory motion.

Results

The technical feasibility of the proposed approach was demonstrated by successful measurements with the combined high‐resolution and real‐time protocol in volunteers. All examinations provided short axis views during the acquisition and angiograms of selected parts of the coronary system after its completion.

Conclusion

The investigated concept allows high‐resolution measurements to be complemented with real‐time imaging functionality without affecting the scan time or image quality. In the particular application considered, an image‐based patient monitoring or motion correction is enabled, indicating potential benefits of combining two very dissimilar methods of data acquisition in one measurement. J. Magn. Reson. Imaging 2002;16:584–590. © 2002 Wiley‐Liss, Inc.
Magnetic resonance safety update 2002: Implants and devices
Authors: Shellock Frank G.
Published: November 2002

The preservation of a safe magnetic resonance (MR) environment requires constant vigilance by MR healthcare professionals, particularly with regard to the management of patients with metallic biomedical implants or devices. The variety and complexity of implants and devices constantly changes, requiring continuous attention and diligence with regard to obtaining the most current and accurate information about these objects relative to the MR environment. This review article discusses MR safety and MR compatibility issues and presents important information for a variety of implants and devices, with an emphasis on those objects that have recently undergone evaluation or that require additional consideration because of existing controversy or confusion. J. Magn. Reson. Imaging 2002;16:485–496. © 2002 Wiley‐Liss, Inc.