bluuebunny/crossref_metadata_2025 huggingface dataset:
Calcium regulation of actin crosslinking is important for function of the actin cytoskeleton inDictyostelium
Authors: Furukawa Ruth , Maselli Andrew , Thomson Susanne A. M. , Lim Rita W. L. , Stokes John V. , Fechheimer Marcus
Published: November 2002

The actin cytoskeleton is sensitive to changes in calcium, which affect contractility, actin-severing proteins, actin-crosslinking proteins and calmodulin-regulated enzymes. To dissect the role of calcium control on the activity of individual proteins from effects of calcium on other processes,calcium-insensitive forms of these proteins were prepared and introduced into living cells to replace a calcium-sensitive form of the same protein. Crosslinking and bundling of actin filaments by the Dictyostelium 34 kDa protein is inhibited in the presence of micromolar free calcium. A modified form of the 34 kDa protein with mutations in the calcium binding EF hand (34 kDa ΔEF2) was prepared using site-directed mutagenesis and expressed in E. coli. Equilibrium dialysis using[45Ca]CaCl2 revealed that the wild-type protein is able to bind one calcium ion with a Kd of 2.4 μM. This calcium binding is absent in the 34 kDa ΔEF2 protein. The actin-binding activity of the 34 kDaΔEF2 protein was equivalent to wildtype but calcium insensitive in vitro. The wild-type and 34 kDa ΔEF2 proteins were expressed in 34-kDa-null and 34 kDa/α-actinin double null mutant Dictyostelium strains to test the hypothesis that calcium regulation of actin crosslinking is important in vivo. The 34 kDa ΔEF2 failed to supply function of the 34 kDa protein important for control of cell size and for normal growth to either of these 34-kDa-null strains. Furthermore, the distribution of the 34 kDa protein and actin were abnormal in cells expressing 34 kDa ΔEF2. Thus, calcium regulation of the formation and/or dissolution of crosslinked actin structures is required for dynamic behavior of the actin cytoskeleton important for cell structure and growth.
Radical styrene polymerization in the presence of trace levels of sulfonic acids
Authors: Matthews Bryan R. , Pike William , Rego Jose M. , Kuch P. D. , Priddy D. B.
Published: December 2002

The bulk polymerization of styrene in the presence of the vinyl functional sulfonic acid 2‐sulfoethylmethacrylate (SEM) was found to have utility for making polystyrenes with narrow polydispersity, bimodal polydispersity, and ultrahigh molecular weight at fast polymerization rates. Narrow polydispersity polymers were made by the addition of SEM to nitroxide‐mediated polymerizations. Bimodal polydispersity polymers were made by the ultrahigh molecular weight component being made in the presence of SEM in the absence of an initiator and the low molecular weight component being made in the presence of an initiator and/or chain‐transfer agent. Ultrahigh molecular weight monomodal polystyrenes were prepared at much faster polymerization rates than possible via spontaneous polymerization in the absence of SEM. SEM was found to be more effective, by an order of magnitude, than camphor sulfonic acid on a weight basis and, because it is copolymerized into the polymer chain, should not lead to corrosion problems during fabrication of the polymer. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 869–875, 2003
Electrochemical polymerization of acrylics on stainless steel cathodes
Authors: Cram S. L. , Spinks G. M. , Wallace G. G. , Brown H. R.
Published: December 2002

A cathodic, aqueous‐based technique for producing uniform, thin, passive films of poly(methyl methacrylate) and poly(glycidylacrylate) on stainless steel electrodes was developed. The films were chemically characterized by Fourier transform infrared spectroscopy, NMR spectroscopy, and differential scanning calorimetry. The thickness (quantified by ellipsometry) and morphology of the films were dependent on the electrolysis time and potential and were also influenced by the individual monomer properties. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 765–773, 2003
Stability of DL‐poly(lactic acid) in aqueous solutions
Authors: Proikakis C. S. , Mamouzelos N. J. , Tarantili P. A. , Andreopoulos A. G.
Published: December 2002

DL‐poly(lactic acid) of molecular weight about 2500 was prepared by polycondensation of lactic acid and characterized by viscosimetry, infrared spectroscopy, light scattering, GPC, and NMR. Tablets made of the above polymer were immersed in buffer solutions at 37°C, and their swelling behavior was recorded as a function of time, in terms of weight gain. In the same experiments, the hydrolytic stability of PLA was assessed by measuring the weight loss after drying the tablets. To inhibit any degradation due to bacteria, formaldehyde was added to the solution as a biostatic factor. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 795–804, 2003
Modification of oil palm empty fruit bunches with maleic anhydride: The effect on the tensile and dimensional stability properties of empty fruit bunch/polypropylene composites
Authors: Rozman H. D. , Saad M. J. , Mohd Ishak Z. A.
Published: December 2002

Oil palm empty fruit bunch (EFB)‐filled polypropylene (PP) composites were produced. The EFB filler was chemically modified with maleic anhydride (MAH). The effects of the filler size and chemical modification of EFBs on the tensile and dimensional stability properties of EFB–PP composites were studied. The composites with MAH‐treated EFBs showed higher tensile strengths than those with untreated EFBs. This was attributed to the enhanced compatibility between the MAH‐treated EFBs and PP matrix, as shown in a scanning electron microscopy study. Fourier transform infrared analysis showed evidence of CC and CO bonds from MAH at 1630 and 1730 cm−1, respectively. The MAH‐treated PP composites showed lower water absorption and thickness swelling than those with untreated EFBs. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 827–835, 2003
Preparation and characterization of poly(ethylene‐co‐vinyl alcohol) membranes via thermally induced liquid–liquid phase separation
Authors: Shang Mengxian , Matsuyama Hideto , Maki Taisuke , Teramoto Masaaki , Lloyd Douglas R.
Published: December 2002

Porous membranes were prepared through the thermally induced phase separation of poly(ethylene‐co‐vinyl alcohol) (EVOH)/glycerol mixtures. The binodal temperature and dynamic crystallization temperature were determined by optical microscopy and differential scanning calorimetry measurements, respectively. It was determined experimentally that the liquid–liquid phase boundaries were shifted to higher temperatures when the ethylene content in EVOH increased. For EVOHs with ethylene contents of 32–44 mol %, liquid–liquid phase separation occurred before crystallization. Cellular pores were formed in these membranes. However, only polymer crystallization (solid–liquid phase separation) occurred for EVOH with a 27 mol % ethylene content, and the membrane morphology was the particulate structure. Scanning electron microscopy showed that the sizes of the cellular pores and crystalline particles in the membranes depended on the ethylene content in EVOH, the polymer concentration, and the cooling rate. Furthermore, the tendency of the pore and particle sizes was examined in terms of the solution thermodynamics of the binary mixture and the crystallization kinetics. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 853–860, 2003
The video suggestibility scale for children: how generalizable is children's performance to other measures of suggestibility?
Authors: McFarlane Felicity , Powell Martine B.
Published: December 2002

This study explored the generalizability of the Video Suggestibility Scale for Children (VSSC), which was developed by Scullin and colleagues (Scullin & Ceci, 2001; Scullin & Hembrooke, 1998) as a tool for discriminating among children (aged three to five years) who have different levels of suggestibility. The VSSC consists of two subscales; Yield (a measure of children's willingness to acquiesce to misleading questions) and Shift (a measure of children's tendency to change their responses after feedback from the interviewer). Children's (N = 77) performance on each of the subscales was compared with their performance using several other measures of suggestibility. These measures included children's willingness to assent to a false event as well as the number of false interviewer suggestions and false new details that the children provided when responding to cued‐recall questions about an independent true–biased and an independent false (non‐experienced) event. An independent samples t‐test revealed that those children who assented to the false event generated higher scores on the Yield measure. Hierarchical regression analyses revealed that Yield was a significant predictor of the number of false details reported about the false activity, but not the true–biased activity. There was no significant relationship between the Shift subscale and any of the dependent variables. The potential contribution of the VSSC for forensic researchers and practitioners is discussed. Copyright © 2002 John Wiley & Sons, Ltd.
Cruise ships and kayaks: welfare and rehabilitation approaches for women with disabilities in poverty
Authors: Foley Susan M. , Marrone Joseph , Simon Mia
Published: December 2002

Women with disabilities have low employment rates and about one‐third live in poverty. They represent half of the population using either services of the vocational rehabilitation (VR) system or the welfare system, and many use both. Although both systems have made gains in improving their employment status, neither comprehensively addresses the needs of this population. Welfare policy has encouraged state level innovation and moved large numbers of people into employment in as little as five years. State welfare agencies offer a range of services specifically addressing the needs of families with children. VR agencies have decades of specific experience assisting people with disabilities gain employment. Welfare reform has been the cruise ship moving large numbers of people across an ocean. VR agencies have been the kayak builders designing specialized small craft to move specific people along tributaries. What can they learn from each other? Copyright © 2002 John Wiley & Sons, Ltd.
Accounting for unemployment among people with mental illness
Authors: Baron Richard C. , Salzer Mark S.
Published: December 2002

Persons diagnosed with a serious mental illness experience significantly high rates of unemployment compared with the general population. The explanations for this situation have included a focus on the symptoms associated with these disorders, a focus on the lack of effective vocational rehabilitation programs for this population, and, most recently, a focus on employer discrimination and the financial disincentives to employment in various public policies. The authors of this manuscript review the evolution in thought pertaining to the labor market experiences of persons with a serious mental illness and propose as an additional set of factors that should be considered, those labor market liabilities that this population shares with others without disabilities who experience similar employment histories. The authors conclude that the inclusion of these factors in our understanding of issues that persons with serious mental illness face in the competitive labor market will likely lead to a further evolution in program and policy development. Copyright © 2002 John Wiley & Sons, Ltd.
Does U.S. federal policy support employment and recovery for people with psychiatric disabilities?
Authors: O'Day Bonnie , Killeen Mary
Published: December 2002

Evidence suggests that a high percentage of people with a psychiatric disability can recover—find meaningful work, develop positive relationships, and participate fully in their communities. Evidence also suggests that work is an essential component of recovery. However, few people with a serious psychiatric disability are actually employed and most of those who are employed work only part‐time at barely minimum wages.

To assess the impact of federal programs such as Social Security Disability Insurance, vocational rehabilitation, medical insurance, and psychiatric services upon employment, we conducted a qualitative study of 16 employed and 16 unemployed individuals with psychiatric disabilities. All of our participants had disabilities severe enough to qualify them for Social Security Disability benefits.

They told us that current federal policies and practices encouraged employment and integration of only a few participants, in a particular stage of their recovery, and placed significant barriers in the employment path of others. Copyright © 2002 John Wiley & Sons, Ltd.
TNFα downregulates PPARδ expression in oligodendrocyte progenitor cells: Implications for demyelinating diseases
Authors: Cimini Annamaria , Bernardo Antonietta , Cifone Grazia , Di Muzio Luisa , Di Loreto Silvia
Published: December 2002

TNFα has been implicated in several demyelinating disorders, including multiple sclerosis (MS) and X‐adrenoleukodystrophy (X‐ALD). TNFα abundance is greatly increased in the areas surrounding damaged regions of the central nervous system of patients with MS and X‐ALD, but its role in the observed demyelination remains to be elucidated. A class of nuclear receptors, the peroxisome proliferator‐activated receptors (PPARs), has been implicated in several physiological and pathological processes. In particular, PPARδ has been shown to promote oligodendrocyte (OL) survival and differentiation and PPARγ has been implicated in inflammation. In the present study, we investigate on the effects of TNFα on OLs during differentiation in vitro. The results obtained show that TNFα treatment impairs PPARδ expression with concomitant decrease of lignocerolyl‐CoA synthase and very‐long‐chain fatty acid β‐oxidation as well as plasmalogen biosynthesis. We propose a hypothetical model possibly explaining the perturbation effects of proinflammatory cytokines on myelin synthesis, maturation, and turnover. GLIA 41:3–14, 2003. © 2003 Wiley‐Liss, Inc.
Alterations in the balance of protein kinase and phosphatase activities and age‐related impairments of synaptic transmission and long‐term potentiation
Authors: Hsu Kuei‐Sen , Huang Chiung‐Chun , Liang Ying‐Ching , Wu Huang‐Ming , Chen Yea‐Lin , Lo Shiow‐Win , Ho Wen‐Chia
Published: December 2002

Aging is associated with an impaired ability to maintain long‐term potentiation (LTP), but the underlying cause of the impairment remains unclear. To gain a better understanding of the cellular and molecular mechanisms responsible for this impairment, the synaptic transmission and plasticity were studied in the CA1 region of hippocampal slices from adult (6–8 months) and poor‐memory (PM)‐aged (23–24 months) rats. The one‐way inhibitory avoidance learning task was used as the behavioral paradigm to screen PM‐aged rats. With intracellular recordings, CA1 neurons of PM‐aged rats exhibited a more hyperpolarized resting membrane potential, reduced input resistance, and increased amplitude of afterhyperpolarization and spike threshold, compared with those in adult rats. Although a reduction in the size of excitatory synaptic response was observed in PM‐aged rats, no obvious differences were found between adult and PM‐aged rats in the pharmacological properties of excitatory synaptic response, paired‐pulse facilitation, or frequency‐dependent facilitation, which was tested with trains of 10 pulses at 1, 5, and 10 Hz. Slices from the PM‐aged rats displayed significantly reduced early‐phase long‐term potentiation (E‐LTP) and late‐phase LTP (L‐LTP), and the entire frequency‐response curve of LTP and LTD is modified to favor LTD induction. The susceptibility of time‐dependent reversal of LTP by low‐frequency afferent stimulation was also facilitated in PM‐aged rats. Bath application of the protein phosphatase inhibitor, calyculin A, enhanced synaptic response in slices from PM‐aged, but not adult, rats. In contrast, application of the cAMP‐dependent protein kinase inhibitors, Rp‐8‐CPT‐cAMPS and KT5720, induced a decrease in synaptic transmission only in slices from the adult rats. Furthermore, the selective β‐adrenergic receptor agonist, isoproterenol, and pertussis toxin‐sensitive G‐protein inhibitor, N‐ethylmaleimide, effectively restored the deficit in E‐LTP and L‐LTP of PM‐aged rats. These results demonstrate that age‐related impairments of synaptic transmission and LTP may result from alterations in the balance of protein kinase/phosphatase activities. Hippocampus 2002;12:787–802. © 2002 Wiley‐Liss, Inc.
Facilitated CA1 hippocampal synaptic plasticity in dystrophin‐deficient mice: Role for GABAA receptors?
Authors: Vaillend Cyrille , Billard Jean‐Marie
Published: December 2002

Duchenne muscular dystrophy (DMD) is associated with cognitive deficits that may result from a deficiency in the brain isoform of the cytoskeletal membrane‐associated protein, dystrophin. CA1 hippocampal short‐term potentiation (STP) of synaptic transmission is increased in dystrophin‐deficient mdx mice, which has been attributed to a facilitated activation of NMDA receptors. In this study, extracellular recordings in the hippocampal slice preparation were used first to determine the consequences of this alteration on short‐term depression (STD). STD induction was facilitated in mdx as compared with wild‐type mice in a control medium. Because brain dystrophin deficiency results in a decreased number of γ‐aminobutyric acid A (GABAA)‐receptor clusters, we tested the hypothesis that neuronal disinhibition contributes to the enhanced synaptic plasticity in mdx mice. We found that the GABAA receptor antagonist, bicuculline, increased basal neurotransmission in wild‐type, but not in mdxmice and prevented the enhanced STP and STD in the CA1 area of slices from mdx mice. The possibility that altered GABA mechanisms underlie the facilitation of NMDA receptor‐dependent synaptic plasticity in mdx mice is discussed. Hippocampus 2002;12:713–717. © 2002 Wiley‐Liss, Inc.
Differential contributions of the parahippocampal place area and the anterior hippocampus to human memory for scenes
Authors: Köhler Stefan , Crane Joelle , Milner Brenda
Published: December 2002

Past neuroimaging research has identified a parahippocampal place area (PPA) in the posterior medial temporal lobe (MTL), which responds preferentially to visual scenes and plays a role in episodic memory for this class of stimuli. In the present positron emission tomography study, we examined to what extent the functional characteristics of the PPA resemble those of other, more anterior MTL regions across various learning and recognition‐memory tasks. We also determined whether the involvement of the PPA in recognition of previously studied scenes is specific to a particular type of scene information. We found that, like the PPA, anterior hippocampal regions showed a novelty response (higher activation for novel than repeated scenes) and a stimulus‐related response (higher activation for scenes than objects) during learning, indicating that MTL structures other than the PPA contribute to the encoding of novel stimulus relationships in scenes. However, these anterior hippocampal regions showed no involvement during recognition of either spatial or nonspatial information contained in scenes. The PPA, by contrast, was consistently involved in recognition of all types of scene details, presumably through interactions with co‐activated parietal and occipitotemporal cortices. We suggest that MTL contributions from the PPA are sufficient to support recognition of scenes when the task can be based on a perceptually based familiarity process. Hippocampus 2002;12:718–723. © 2002 Wiley‐Liss, Inc.
Progressive supranuclear palsy diagnosis and confounding features: Report on 16 autopsied cases
Authors: Birdi Sam , Rajput Ali H. , Fenton Mark , Donat Jeffery R. , Rozdilsky Bohdan , Robinson Christopher , Macaulay Rob , George David
Published: December 2002

We evaluated 16 (15 men, 1 woman) autopsy‐verified progressive supranuclear palsy (PSP) cases during 31 years (1969–2000) for clinical diagnosis and the course of the disease. The onset was gait difficulty or postural instability in 9 (56.3%), general motor slowing in 3 (18.8%), and tremor in 2. One case had onset with cognitive decline and 1 as hemidystonia. Four cases had supranuclear ophthalmoplegia (SNO) at the first assessment and were diagnosed as PSP. By last assessment, PSP diagnosis was made in 4 additional cases, but in 8 (50%) who never manifested ophthalmoplegia (mean 9.8 years after onset), PSP diagnosis was not made. Other manifestations included bulbar symptoms in 13 (81.3%), and cognitive impairment in 10 (62.5%) during the course of illness. Fifteen cases received levodopa, amantadine, anticholinergics, dopamine agonists, and selegiline in different combinations with symptomatic benefit in 9 of 15 (60%). Five had some improvement on levodopa alone and 3 showed more improvement when a dopamine agonist was added to levodopa. In general, the benefit was minimal and occurred only early in the course of illness. The mean age at onset was 63.7 (range, 53–85) years. Mean duration at PSP diagnosis was 4.8 (range, 2–11) years. Mean survival was 8.6 (range, 3–24) years and mean age at death was 72.3 (range, 60–89) years. When the different diagnostic criteria recommended in the literature were used, the accuracy of clinical diagnosis did not improve substantially. © 2002 Movement Disorder Society
Cabergoline plasma concentration is increased during concomitant treatment with itraconazole
Authors: Christensen Jakob , Dupont Erik , Østergaard Karen
Published: December 2002

We report on 2 patients with idiopathic Parkinson's disease who experienced marked improvement in symptoms following the addition of itraconazole to current cabergoline treatment. Plasma levels of cabergoline were analyzed in one of the patients and increased to approximately 300% during treatment with itraconazole, which paralleled major clinical improvement. © 2002 Movement Disorder Society
The power of cueing to circumvent dopamine deficits: A review of physical therapy treatment of gait disturbances in Parkinson's disease
Authors: Rubinstein Tamar C. , Giladi Nir , Hausdorff Jeffrey M.
Published: December 2002

Gait disturbances are among the primary symptoms of Parkinson's disease (PD) and contribute significantly to a patient's loss of function and independence. Standard treatment includes antiparkinsonian drugs, primarily levodopa. In addition to the standard drug regime, physical therapy is often prescribed to help manage the disease. In recent years, there have been promising reports of physical therapy programs combined with various types of sensory cueing for PD. In this brief review of the literature, we summarize the evidence regarding the clinical efficacy of different physical therapy programs for PD, specifically with respect to improving gait. We also discuss the potential therapeutic mechanisms of sensory cueing and review the studies that have used cueing in the treatment of gait in PD. This review of the literature shows two key findings: (1) despite its relatively long history, the evidence supporting the efficacy of conventional physical therapy for treatment of gait in PD is not strong; and (2) although further investigation is needed, sensory cueing appears to be a powerful means of improving gait in PD. © 2002 Movement Disorder Society
Transient mania with hypersexuality after surgery for high frequency stimulation of the subthalamic nucleus in Parkinson's disease
Authors: Romito Luigi Michele , Raja Michele , Daniele Antonio , Contarino Maria Fiorella , Bentivoglio Anna Rita , Barbier Annalisa , Scerrati Massimo , Albanese Alberto
Published: December 2002

Among 30 Parkinson's disease patients who received high frequency stimulation of the subthalamic nucleus, 5 developed remarkable disorders of mood or sexual behavior after the implant. We describe 2 men who developed mania and hypersexuality a few days after the implant that lasted for some months and then gradually disappeared spontaneously. © 2002 Movement Disorder Society
Case‐Control study of dopamine transporter‐1, monoamine oxidase‐B, and catechol‐O‐methyl transferase polymorphisms in Parkinson's disease
Authors: Goudreau John L. , Maraganore Demetrius M. , Farrer Matthew J. , Lesnick Timothy G. , Singleton Andrew B. , Bower James H. , Hardy John A. , Rocca Walter A.
Published: December 2002

We investigated the association of Parkinson's disease (PD) with dopamine transporter‐1 (DAT1), monoamine oxidase‐B (MAO‐B), and catechol‐O‐methyltransferase (COMT) gene polymorphisms. Overall, we observed no significant association of PD with the DAT1‐3′–variable numbers of tandem repeats, the MAO‐B‐(GT)n, and the COMT‐Val108Met gene polymorphisms in a sample of 319 unrelated PD cases and 196 control subjects. Analyses stratified by sex, age at examination, family history of PD, and ethnic origin also yielded negative findings, with three exceptions. We found statistically significant associations of PD with MAO‐B polymorphisms in older patients and with a COMT polymorphism in younger subjects and in women. These significant differences at the two‐tailed alpha level of 0.05 and restricted to subgroup analyses may have a biological basis or may be chance findings. © 2002 Movement Disorder Society
Sublingual Atropine for sialorrhea secondary to parkinsonism: A pilot study
Authors: Hyson H. Christopher , Johnson Andrew M. , Jog Mandar S.
Published: December 2002

Sialorrhea is a relatively common symptom in idiopathic Parkinson's disease and related conditions for which most of the accepted treatments are either highly invasive or may cause substantial systemic side effects. This study describes an open‐label pilot study of sublingual atropine drops for the treatment of sialorrhea in 7 patients (6 with Parkinson's disease, 1 with progressive supranuclear palsy). Participants demonstrated statistically significant declines in saliva production, both objectively and subjectively. Self‐reported drooling severity showed a significant decline between baseline and 180 minutes, t(6) = 3.240 P < 0.025 (η2 = 0.636), and between baseline and 1 week, t(6) = 4.583 P < 0.005 (η2 = 0.778). Objectively measured saliva production decreased significantly between baseline and the 1‐week follow‐up, t(6) = 2.711 P < 0.05 (η2 = 0.551). Delirium occurred in 1 patient (concurrent with a urinary tract infection), and 2 patients experienced worsening of hallucinations (active hallucinosis was concealed by both individuals to allow participation in the trial). The remaining trial participants did not experience any anticholinergic side effects. This trial shows that, in selected patient populations, sublingual atropine is a simple and inexpensive treatment for sialorrhea associated with parkinsonism. © 2002 Movement Disorder Society
Holmes' tremor and neuroparacoccidioidomycosis: A case report
Authors: Teive Hélio A.G. , Zanatta Alessandra , Germiniani Francisco M.B. , Almeida Sérgio M. , Werneck Lineu C.
Published: December 2002

We report on a case of neuroparacoccidioidomycosis that presented with a midbrain mass lesion associated with Holmes' tremor. The difficulties of pharmacological treatment of such tremor are emphasized. © 2002 Movement Disorder Society
Forty‐one year follow‐up of childhood‐onset opsoclonus‐myoclonus‐ataxia: Cerebellar atrophy, multiphasic relapses, and response to IVIG
Authors: Pranzatelli Michael R. , Tate Elizabeth D. , Kinsbourne Marcel , Caviness Verne S. , Mishra Bibhuti
Published: December 2002

We report on an adult with opsoclonus‐myoclonus‐ataxia syndrome experiencing widely spaced neurological relapses, who was followed for 41 years. His responses to treatment are described. © 2002 Movement Disorder Society
Further case of paroxysmal exercise‐induced dystonia and some insights into pathogenesis
Authors: Barnett Michael H. , Jarman Paul R. , Heales Simon J.R. , Bhatia Kailash P.
Published: December 2002

Cerebrospinal fluid (CSF) analysis of pterin and monamine metabolites was performed before and after an attack in a patient with paroxysmal exercise‐induced dystonia. A twofold increase in CSF homovanillic acid and 5‐hydroxyindoleacetic acid after an attack was measured. This finding lends support to the hypothesis that increased dopaminergic transmission contributes to the clinical features of the hyperkinetic movement disorders. © 2002 Movement Disorder Society
Method for efficient fast spin echo Dixon imaging
Authors: Ma Jingfei , Singh Sanjay K. , Kumar Ashok J. , Leeds Norman E. , Broemeling Lyle D.
Published: December 2002

In order to satisfy the Carr‐Purcell‐Meiboom‐Gill (CPMG) condition, echo shift as dictated in fast‐spin‐echo (FSE)‐based Dixon imaging was previously achieved by applying a time shift to the readout gradient and the data acquisition window. Accordingly, interecho spacing is increased, which entails increased image blurring and, in multislice imaging, a significant reduction in the slice coverage for a given imaging time. In this work, a new method is developed by which the echo shift is induced by “sandwiching” in time the readout gradient with a pair of small gradients of equal area and of opposite polarity. While data with non‐zero phase shifts between water and fat signals are collected as fractional echoes, no increase in echo spacing is necessary with the modified acquisition strategy, and increased time efficiency is therefore achieved. In order to generate separate water‐only and fat‐only images in data processing, a set of low‐resolution images are first reconstructed from the central symmetric portion (either 128 × 128 or 64 × 64) of the acquired multipoint Dixon data. High‐resolution images using all the acquired data, including some partial Fourier‐reconstructed images, are then phase demodulated using the phase errors determined from the low‐resolution images. The feasibility of the technique is demonstrated using a water and fat phantom as well as in clinical patient imaging. Magn Reson Med 48:1021–1027, 2002. © 2002 Wiley‐Liss, Inc.
Reproducibility of localized 2D correlated MR spectroscopy
Authors: Binesh Nader , Yue Kenneth , Fairbanks Lynn , Thomas M. Albert
Published: December 2002

The test‐retest reliability of two‐dimensional (2D) correlated spectroscopy (COSY) was studied on a whole‐body 1.5T MRI scanner. Single‐voxel localized 2D proton spectra were recorded in vitro as well as in vivo using a recently implemented localized chemical shift correlated spectroscopic (L‐COSY) sequence. A total of 40 in vitro and 40 human brain (10 volunteers, four times each) 2D L‐COSY spectra were recorded. The coefficients of variation (CVs) of selected brain metabolites (raw volume integrals) recorded in 10 healthy volunteers were less than 9% for creatine, choline, and N‐acetyl aspartate, and less than 17% for myo‐inositol, glutamine/glutamate, aspartate, and threonine/lactate. The 2D metabolite ratios and the raw volume integrals of 2D diagonal and cross peaks in healthy human brain were very well reproduced. The intraclass correlation coefficients were greater than 0.4 (P < 0.05) for the major metabolites, indicating that the 2D peak volumes were stable enough within individuals to detect reliable differences between normal subjects. Magn Reson Med 48:942–948, 2002. © 2002 Wiley‐Liss, Inc.
Band artifacts due to bulk motion
Authors: Storey Pippa , Chen Qun , Li Wei , Edelman Robert R. , Prasad Pottumarthi V.
Published: December 2002

Band artifacts due to bulk motion were investigated in images acquired with fast gradient echo sequences. A simple analytical calculation shows that the width of the artifacts has a square‐root dependence on the velocity of the imaged object, the time taken to acquire each line of k‐space and the field of view in the phase‐encoding direction. The theory furthermore predicts that the artifact width can be reduced using parallel imaging by a factor equal to the square root of the acceleration parameter. The analysis and results are presented for motion in the phase‐ and frequency‐encoding directions and comparisons are made between sequential and centric ordering. The theory is validated in phantom experiments, in which bulk motion is simulated in a controlled and reproducible manner by rocking the scan table back and forth along the bore axis. Preliminary cardiac studies in healthy human volunteers show that dark bands may be observed in the endocardium in images acquired with nonsegmented fast gradient echo sequences. The fact that the position of the bands changes with the phase‐encoding direction suggests that they may be artifacts due to motion of the heart walls during the image acquisition period. Magn Reson Med 48:1028–1036, 2002. © 2002 Wiley‐Liss, Inc.
FIESTA‐ET: High‐resolution cardiac imaging using echo‐planar steady‐state free precession
Authors: Slavin Glenn S. , Saranathan Manojkumar
Published: December 2002

This work describes a technique that combines multishot echo‐planar imaging (EPI) with steady‐state free precession (SSFP, also known as TrueFISP, FIESTA, and balanced FFE) for multislice, cine MR imaging of the heart. Unlike recently reported methods, the technique presented here (FIESTA‐ET) is high‐resolution and does not require offline reconstruction or postprocessing. It is therefore suitable for use on standard clinical scanners. FIESTA‐ET was compared with conventional FIESTA imaging in 10 volunteers and quantitative analyses of myocardial signal‐to‐noise ratios (SNR) and ventricular volumes were performed. While providing comparable image quality, FIESTA‐ET required half the acquisition time per slice of conventional FIESTA. Because multiple slices could be imaged in a single breathhold, the entire heart could be scanned in less than 2 min. Although the FIESTA‐ET images exhibited an unexpected increase (P < 0.0005) in myocardial SNR of 16% over FIESTA, the volumetric measurements showed excellent correlation. Magn Reson Med 48:934–941, 2002. © 2002 Wiley‐Liss, Inc.
Relaxivity and diffusion of gadolinium agents in cartilage
Authors: Gillis Amy , Gray Martha , Burstein Deborah
Published: December 2002

Prior work indicates that the distribution of Gd(DTPA)2‐ (as measured by T1) is a good surrogate measure of the distribution of gycosaminoglycan (GAG) in cartilage. In addition to the measured T1 in the presence of Gd(DTPA)2‐, the precision of the measurement of Gd(DTPA)2‐ concentration depends on the T1 without Gd(DTPA)2‐ (T), and the relaxivity (r) of Gd(DTPA)2‐ in cartilage, parameters that are influenced by cartilage composition. These parameters were measured in native and GAG‐depleted cartilage in order to estimate the bounds on the values one might expect for cartilage in arbitrary states of degeneration. The range of T was 0.3 sec; the range of r was 0.6 (mM*s)‐1 at 8.5 T and 1.4 (mM*s)‐1 at 2 T. These data suggest that Gd(DTPA)2‐ will be underestimated (and GAG overestimated) if the values for T and r are assumed to be those of native cartilage. (For example, in a severe case a 90% loss of GAG would be underestimated as a 70% loss.) Gd(HPDO3A) was investigated as a nonionic “control agent” and found to have relaxivity and diffusion properties that were comparable to Gd(DTPA)2‐ (rGd(HPDO3A)/rGd(DTPA) ≈ 1; DGd(HPDO3A)/DGd(DTPA) ≈ 0.85). Since Gd(HPDO3A) distributes uniformly through cartilage (independent of GAG), the distribution of T1 with Gd(HPDO3A) can be used as a surrogate measure of variations in T and r, if present. From the perspective of transport, if Gd(HPDO3A) has fully penetrated the cartilage, Gd(DTPA)2‐ would have in the same time frame. Therefore, the data confirm the efficacy of using Gd(HPDO3A) as a “control agent” for dGEMRIC. Magn Reson Med 48:1068–1071, 2002. © 2002 Wiley‐Liss, Inc.
Automatic selection of mask and arterial phase images for temporally resolved MR digital subtraction angiography
Authors: Kim Junhwan , Prince Martin R. , Zabih Ramin , Bezanson Jeff , Watts Richard , Erel Hale E. , Wang Yi
Published: December 2002

For time‐resolved background‐subtracted contrast‐enhanced magnetic resonance angiography, the bright and sparse arterial signal allows unique identification of contrast bolus arrival in the arteries. This article presents an automatic filtering algorithm using such arterial characterization for selecting arterial phase images and mask images to generate an optimal summary arteriogram. A paired double‐blinded comparison demonstrated that this automatic algorithm is as effective as the manual process. Magn Reson Med 48:1004–1010, 2002. © 2002 Wiley‐Liss, Inc.
An electrokinetic model of drop deformation in
an electric field
Authors: ZHOLKOVSKIJ EMILIJ K. , MASLIYAH JACOB H. , CZARNECKI JAN
Published: December 2002

An electrokinetic model is proposed to describe a slight drop deformation which is
induced by a weak external electric field. The fluids forming the system are considered
Newtonian incompressible dielectric liquids containing free electric charge carriers.
According to the model, the charge carriers take part in migration, diffusion and
convection transport and there is no solute adsorption at the interface. Thermodynamic
quasi-equilibrium at the interface is assumed for the charge carriers in the
contacting liquids. The interfacial thermodynamic equilibrium is described using a
common distribution coefficient for all the carriers. The problem is simplified by
assuming equal diffusion coefficients for the different charge carriers within the same
liquid. An analytical expression is obtained for slight drop deformation which is proportional
to the second power of the applied field strength magnitude. The expression
derived represents the drop deformation as a function of the parameters employed
in previous theories (O’Konski & Thacher 1953; Allan & Mason 1962; Taylor 1966)
as well as two additional parameters. The additional parameters are the ratios of
the drop radius to the Debye lengths of the outer and inner liquids, respectively.
The expression obtained for the drop deformation is valid for arbitrary values of
these parameters. According to the theory prediction, with an increase in the drop
radius, the drop deformation monotonically changes from that obtained by O’Konski
& Thacher (1953) and Allan & Mason (1962) for perfect dielectric liquids to that
obtained by Taylor (1966) for leaky dielectric liquids. Two simplified versions of the
general expression are suggested to describe particular cases of a conducting drop in
a perfect dielectric liquid and of a perfect dielectric drop in a conducting liquid.
Stability of fluid flow past a membrane
Authors: THAOKAR R. M. , KUMARAN V.
Published: December 2002

The stability of fluid flow past a membrane of infinitesimal thickness is analysed in
the limit of zero Reynolds number using linear and weakly nonlinear analyses. The
system consists of two Newtonian fluids of thickness R* and HR*, separated by an
infinitesimally thick membrane, which is flat in the unperturbed state. The dynamics
of the membrane is described by its normal displacement from the flat state, as well
as a surface displacement field which provides the displacement of material points
from their steady-state positions due to the tangential stress exerted by the fluid
flow. The surface stress in the membrane (force per unit length) contains an elastic
component proportional to the strain along the surface of the membrane, and a
viscous component proportional to the strain rate. The linear analysis reveals that the
fluctuations become unstable in the long-wave (α→0) limit when the non-dimensional
strain rate in the fluid exceeds a critical value Λt, and this critical value increases
proportional to α2 in this limit. Here, α is the dimensionless wavenumber of the
perturbations scaled by the inverse of the fluid thickness R*−1, and the dimensionless
strain rate is given by Λt = (γ˙*R*η*/Γ*), where η* is the fluid viscosity, Γ* is the
tension of the membrane and γ˙* is the strain rate in the fluid. The weakly nonlinear
stability analysis shows that perturbations are supercritically stable in the α→0 limit.
Experiments on stability and transition
at Mach 3
Authors: GRAZIOSI PAOLO , BROWN GARRY L.
Published: December 2002

The results of an experimental study of stability, receptivity and transition of the
flat-plate laminar boundary layer at Mach 3 are discussed. With a relatively low free-stream
disturbance level (∼0.1%), spectra, growth rates and amplitude distributions
of naturally occurring boundary layer waves were measured using hot wires. Physical
(mass-flux) amplitudes in the boundary layer and free stream are reported and provide
stability and receptivity results against which predictions can be directly compared.
Comparisons are made between measurements of growth rates of unstable high-frequency
waves and theoretical predictions based on a non-parallel, mode-averaging
stability theory and receptivity assumptions; good agreement is found. In contrast,
it was found that linear stability theory does not account for the measured growth
of low-frequency disturbances. A detailed investigation of the disturbance fields in
the free stream and on the nozzle walls provides the basis for a discussion of the
source and the development of the measured boundary layer waves. Attention is
drawn to the close matching in streamwise wavelengths for instability waves and the
free-stream acoustic disturbances. It was also found that a calibration of the hot
wire in the free stream yields a double-peak boundary layer disturbance amplitude
distribution, as has been found by previous investigators, which is not consistent
with the predictions of linear stability theory. This double peak was found to be
an experimental anomaly which resulted from assumptions that are frequently made
in the free-stream calibration procedure. A single-peak amplitude distribution across
the boundary layer was established only when the hot-wire voltage was calibrated
against the mean boundary layer profile. Finally, the late stages of transition, at a
higher Reynolds number with a higher free-stream disturbance level, were explored.
Calibrated amplitude levels are provided at locations where nonlinearities are first
detected and where the mean boundary layer profile is first observed to depart from
the laminar similarity solution. A qualitative discussion of the character of ensuing
nonlinearities is also included.
Fission of collapsing cavitation bubbles
Authors: BRENNEN CHRISTOPHER E.
Published: December 2002

High-speed observations clearly show that though a collapsing cavitation bubble
approaches its minimum size as a coherent single volume, it usually reappears in
the first rebounding frame as a cloud of much smaller bubbles or as a highly
distorted single volume. This paper explores two mechanisms that may be responsible
for that bubble fission process, one invoking a Rayleigh–Taylor stability analysis
and the other using the so-called microjet mechanism. Both approaches are shown
to lead to qualitatively similar values for the number of fission fragments and
the paper investigates the flow parameters that effect that number. Finally, the
additional damping of the Rayleigh–Plesset single-bubble calculation caused by the
fission process is investigated; it is shown that the fission damping dominates other
contributions normally considered and is consistent with the number of collapses and
rebounds that are observed to occur in experiments.
The fate of an African ‘chaebol’: Malawi's Press Corporation after democratisation
Authors: van Donge Jan Kees
Published: December 2002

Press Corporation, a large diversified Malawian company, was the personal property of Kamuzu Banda who ruled Malawi as a dictator for thirty years from independence in 1964. The history of Press is analysed in order to generate insights into the relationship between politics and economics in Africa. Comparative references are made to the experience of East Asian countries, as there are important similarities between their development paths and that of Malawi under Banda. The activities of Press Corporation were, in general, similar to parastatal companies elsewhere in Africa but, unlike the latter, Press was profitable and viable as a commercial entity. This challenges the idea that there is a compelling logic in African patrimonialist politics which necessitates parasitism on the economy. The experience of Press points to the value of such large multisectoral companies, as they can mobilise scarce local savings and channel them as venture capital into areas where investment has large external benefits, while the discipline of the profit and loss account in the company is not lost.
Business associations and growth coalitions in Sub-Saharan Africa
Authors: Bräutigam Deborah , Rakner Lise , Taylor Scott
Published: December 2002

Why are ‘growth coalitions’ involving business interest groups and governments so rare in Africa? How has democratisation affected the possibilities for growth coalitions? In three cases with varying degrees of democracy – Mauritius, Zambia, and Zimbabwe – we find that hypotheses about growth coalitions that place importance on the organisation of the business sector are generally borne out. Yet even when the business community is organised in an ‘ideal’ manner, growth coalitions still depend on factors within the state: leadership, ideas, and capacity. Democratisation has a mixed effect. We find that in the case of Zambia, business–state relations did not improve despite a pro-democracy stance by business and the pro-business agenda of the democratic government coming to power in 1991. In Zimbabwe, the erosion of democracy reduced business access to state elites, breaking up a growth coalition that initially showed considerable promise. In Mauritius, the strengthening of democracy has paralleled the deepening of the growth coalition, and both have been reinforced by a strong economy. Our study shows that growth coalitions are possible in Africa; the key lies in determining the conditions under which such coalitions can be sustained in Africa's fragile polities.
Can refugees benefit the state? Refugee resources and African statebuilding
Authors: Jacobsen Karen
Published: December 2002

Refugees impose a variety of security, economic and environmental burdens on host countries, but also embody a significant flow of resources in the form of international humanitarian assistance, economic assets and human capital. These refugee resources represent an important statebuilding contribution to the host state, but security problems and other hindrances inhibit the state's ability to access and control them. This article explores the challenges and opportunities for African states arising from the double impact of refugee-generated resources and security problems. It argues that the potential benefit for the state and its citizens go beyond the burdens imposed by a mass influx. Refugee resources and security threats potentially provide long-term gains, and, by compelling the state to strengthen its grip on border areas, enable the state to ‘harden’ its presence there. However, for host states to realise the potential of refugee resources and continue hosting refugees, they must be assisted by appropriate humanitarian programmes.