bluuebunny/crossref_metadata_2025 huggingface dataset:
Magnetic resonance imaging and permanent cosmetics (tattoos): Survey of complications and adverse events
Authors: Tope Whitney D. , Shellock Frank G.
Published: August 2002

Purpose

To use a survey to determine the incidence of complications and adverse events in individuals with permanent cosmetics (e.g., tattooed eyeliner, eyebrows, lips, cheeks, etc.) who underwent magnetic resonance (MR) imaging.

Materials and Methods

A questionnaire was distributed to clients of cosmetic tattoo technicians. This survey asked study subjects for demographic data, information about their tattoos, and for their experiences during MR imaging procedures.

Results

Data obtained from 1032 surveys were tabulated. One hundred thirty‐five (13.1%) study subjects underwent MR imaging after having permanent cosmetics applied. Of these, only two individuals (1.5%) experienced problems associated with MR imaging. One subject reported a sensation of “slight tingling” and the other subject reported a sensation of “burning”; both sensations were transient in nature.

Conclusion

Based on these findings and information in the peer‐reviewed literature, it appears that MR imaging may be performed in patients with permanent cosmetics without any serious soft tissue reactions or adverse events. Therefore, the presence of permanent cosmetics should not prevent a patient from undergoing MR imaging. J. Magn. Reson. Imaging 2002;15:180–184. © 2002 Wiley‐Liss, Inc.
The reproducibility and sensitivity of brain tissue volume measurements derived from an SPM‐based segmentation methodology
Authors: Chard Declan T. , Parker Geoffrey J.M. , Griffin Colette M.B. , Thompson Alan J. , Miller David H.
Published: August 2002

Purpose

To investigate the reproducibility of SPM99‐based whole brain, gray matter, and white matter volume measurements with and without image inhomogeneity correction, subsequently exploring age and gender effects on absolute and fractional (proportional to intra‐cranial) volumes.

Materials and Methods

Twenty‐seven control subjects (aged 23.2 to 55.2 years) had three‐dimensional fast spoiled gradient recall scans. Ten subjects were scanned about 197 days later.

Results

Coefficients of variation (CV) for absolute and fractional volumes determined from images processed with inhomogeneity correction ranged from 1.2% to 0.5%. Inhomogeneity correction reduced the CV for all measures except gray matter fractional (GMF) volumes. Significantly lower white matter absolute (WM) and fractional (WMF) volumes, and higher GMF were found in females compared with males, overlying age‐related reductions (in decreasing order of significance) in brain parenchymal fraction, GMF, WMF, brain parenchymal, and gray matter volumes.

Conclusion

SPM99 segmentations are sufficiently reproducible to detect age and gender effects in limited cohorts J. Magn. Reson. Imaging 2002;15:259–267. © 2002 Wiley‐Liss, Inc.
A new gadolinium‐based contrast agent for magnetic resonance imaging of brain tumors: Kinetic study on a C6 rat glioma model
Authors: Fonchy Emmanuel , Lahrech Hana , François‐Joubert Anne , Dupeyre Roger , Benderbous Soraya , Corot Claire , Farion Régine , Rubin Christophe , Décorps Michel , Rémy Chantal
Published: August 2002

T1‐weighted magnetic resonance imaging (MRI) was used to evaluate the potential interest of a new Gd‐based contrast agent, termed P760, to characterize brain tumor heterogeneity and vascularization and to delineate regions containing permeable vessels. The C6 rat glioma model was used as a model of high‐grade glioblastoma. The signal enhancement was measured as a function of time in the vascular compartment and in different regions of interest (ROIs) within the tumor after the injection of 0.02 mmol kg−1 of P760. The results were compared to those obtained after the injection of 0.1 mmol kg−1 of Gd‐DOTA. We showed that P760, in spite of a Gd concentration five times smaller, produces an enhancement in the blood pool similar to that produced by Gd‐DOTA. It was shown that P760 makes possible an excellent delineation of regions containing vessels with a damaged blood‐brain barrier (BBB). Images acquired 5–10 minutes after P760 injection showed the location of permeable vessels more accurately than Gd‐DOTA‐enhanced images. The enhancement produced in the tumor by P760 was, however, less than that produced by Gd‐DOTA. The extravasation and/or diffusion rate of P760 in the interstitial medium were found to be strongly reduced, compared to those found with Gd‐DOTA. This study suggests that the new contrast agent has promising capabilities in clinical imaging of brain tumors. J. Magn. Reson. Imaging 2001;14:97–105. © 2001 Wiley‐Liss, Inc.
In vivo studies of Gd‐DTPA‐monoclonal antibody and gd‐porphyrins: Potential magnetic resonance imaging contrast agents for melanoma
Authors: Shahbazi‐Gahrouei D. , Williams M. , Rizvi S. , Allen B. J.
Published: August 2002

New tumor‐specific contrast agents for clinical imaging and therapy for cancer are required. To this end Gd‐H (Gd‐hematoporphyrin), Gd‐TCP (Gd‐tetra‐carboranylmethoxyphenyl‐porphyrin), Gd‐DTPA‐WM53, and Gd‐DTPA‐9.2.27 were synthesized and administered by systemic injection to nude mice with human melanoma (MM‐138) xenografts. The biodistribution T1 relaxation times and magnetic resonance (MR) image signal enhancement of the contrast agents are presented for the first time and compared for each group of five mice. A change (20%) in T1 relaxation times of water in human melanoma tumor xenografts was revealed 24 hours after injection of the labeled immunoconjugate Gd‐DTPA‐9.2.27. The percent of injected antibody or gadolinium that localized to the tumor was measured by inductively coupled plasma atomic emission spectroscopy (ICP‐AES) to be approximately 35%. A higher concentration of gadolinium was achieved compared with nonspecific compounds, indicating selective delivery of Gd‐DTPA‐9.2.27 to the melanoma xenografts. Porphyrin‐based contrast agents (Gd‐H and Gd‐TCP) also showed significant uptake in melanomas. The uptake of Gd‐TCP by the tumor was sufficient to deliver boron atoms into the tumor, making possible dual use for both MR imaging (MRI) and boron neutron capture therapy (BNCT). The linear relationship found between the paramagnetic contribution to the relaxation rates and contrast agent concentration allows quantitative studies of paramagnetic contrast agent uptake. J. Magn. Reson. Imaging 2001;14:169–174. © 2001 Wiley‐Liss, Inc.
Steady‐state free precession magnetic resonance imaging of the heart: Comparison with segmented k‐space gradient‐echo imaging
Authors: Plein Sven , Bloomer Timothy N. , Ridgway John P. , Jones Tim R. , Bainbridge Gavin J. , Sivananthan Mohan U.
Published: August 2002

Steady‐state free precession imaging is a promising technique for cardiac magnetic resonance imaging (MRI), as it provides improved blood/myocardial contrast in shorter acquisition times compared with conventional gradient‐echo acquisition. The better contrast could improve observer agreement and automatic detection of cardiac contours for volumetric assessment of the ventricles, but measurements might differ from those obtained using conventional methods. We compared volumetric measurements, observer variabilities, and automatic contour detection between a steady‐state free precession imaging sequence (BFFE = balanced fast field echo) and segmented k‐space gradient‐echo acquisition (TFE = turbo field echo) in 41 subjects. With BFFE, significantly higher end‐diastolic and end‐systolic volumes and lower wall thickness, ventricular mass, ejection fraction, and wall motion were observed (P < 0.0001), while interobserver variabilities were lower and automatic contour detection of endocardial contours was more successful. We conclude that the improved image quality of BFFE reduces the observer‐dependence of volumetric measurements of the left ventricle (LV) but results in significantly different values in comparison to TFE measurements. J. Magn. Reson. Imaging 2001;14:230–236. © 2001 Wiley‐Liss, Inc.
Effect of eluent on the ionization efficiency of flavonoids by ion spray, atmospheric pressure chemical ionization, and atmospheric pressure photoionization mass spectrometry
Authors: Rauha Jussi‐Pekka , Vuorela Heikki , Kostiainen Risto
Published: August 2002

The effect of nine different eluent compositions on the ionization efficiency of five flavonoids was studied using ion spray (IS), atmospheric pressure chemical ionization (APCI), and the novel atmospheric pressure photoionization (APPI), in positive and negative ion modes. The eluent composition had a great effect on the ionization efficiency, and the optimal ionization conditions were achieved in positive ion IS and APCI using 0.4% formic acid (pH 2.3) as a buffer, and in negative ion IS and APCI using ammonium acetate buffer adjusted to pH 4.0. For APPI work, the eluent of choice appeared to be a mixture of organic solvent and 5 mM aqueous ammonium acetate. The limits of detection (LODs) were determined in scan mode for the analytes by liquid chromatography/mass spectrometry using IS, APCI and APPI interfaces. The results show that negative ion IS with an eluent system consisting of acidic ammonium acetate buffer provides the best conditions for detection of flavonoids in mass spectrometry mode, their LODs being between 0.8 and 13 µM for an injection volume of 20 µl. Copyright © 2001 John Wiley & Sons, Ltd.
Human cytomegalovirus hyperimmune globulin not only neutralizes HCMV infectivity, but also inhibits HCMV‐induced intracellular NF‐κB, Sp1, and PI3‐K signaling pathways
Authors: Andreoni Kenneth A. , Wang Xin , Huang Shu‐Mei , Huang Eng‐Shang
Published: August 2002

Inhibition of virus‐induced intracellular signaling pathways and viral infectivity are our ultimate goals in the development of effective antiviral agents to control human cytomegalovirus (HCMV) infections. The HCMV hyperimmune globulin may meet such criteria. In a human embryonic lung (HEL) fibroblast culture model, pretreatment of Towne strain HCMV with HCMV hyperimmune globulin was shown to inhibit viral infectivity successfully, as measured by a standard plaque assay. The extracellular viral titers and extracellular viral DNA, as measured by plaque assay and PCR, respectively, were also decreased. In addition, the HCMV hyperimmune globulin prevented HCMV from inducing the intracellular activation of NF‐κB, Sp‐1, and PI3‐K signaling pathways. The PI3‐K pathway was examined by following phosphorylation (activation) of two of its downstream kinases, Akt and p70S6K. HCMV hyperimmune globulin also prevented the production of immediate early, early, and late viral proteins. These studies show that HCMV hyperimmune globulin neutralization of HCMV prevents the earliest known events observed after viral envelope glycoproteins bind their cell membrane receptors, i.e., NF‐κB, Sp‐1 and PI3‐K activation. This suggests that HCMV hyperimmune globulin not only can inhibit viral infectivity, but can also prevent the abnormal cellular signaling that may induce unwanted cellular proliferation or cytokine synthesis. J. Med. Virol. 67:33–40, 2002. © 2002 Wiley‐Liss, Inc.
Simulation of EM wave propagation in magnetoelectric media using TLM
Authors: Christopoulos Christos , Paul John , Thomas David W. P.
Published: August 2002

In this paper, the simulation of general frequency‐dependent magnetoelectric material properties in time‐domain TLM is described. The formulation is developed from Maxwell's equations and the constitutive relations using bilinear 𝒵‐transform methods leading to a general Padé system. The approach is applicable to all frequency‐dependent linear materials including those displaying anisotropic and bianisotropic behaviour. The method is validated by the example of a chiral slab having an analytic solution. Copyright © 2001 John Wiley & Sons, Ltd.
Changes in the cellular distribution of glutamine synthetase in Alzheimer's disease
Authors: Robinson Stephen R.
Published: August 2002

The intracellular localization of glutamine synthetase (GS) in the inferior temporal cortices of non‐demented elderly individuals was compared with that in brains affected by Alzheimer's disease (AD). The present study confirmed previous reports of a general decrease in GS expression in astrocytes and the expression of GS in some neurons. Several new observations were made: the morphology of astrocytes is generally unaffected by the presence of plaques, GS labeling is present in some diffuse plaques and occasional neuritic plaques, whereas the overall density of astrocytes increases 1.4‐fold in AD. In addition, the present study found that the reduction in GS expression is almost entirely due to a loss of GS from perisynaptic regions of the neuropil and from the astrocytic endfeet that normally abut cortical blood vessels. These changes implicate astrocytes in glutamate excitotoxicity and ammonia neurotoxicity. It is suggested that it may be more fruitful to regard AD not as a neuronal disease, but as a disorder of astrocyte‐neuron interactions. © 2001 Wiley‐Liss, Inc.
Differential expression of glutamate dehydrogenase in cultured neurons and astrocytes from mouse cerebellum and cerebral cortex
Authors: Zaganas Ioannis , Waagepetersen Helle S. , Georgopoulos Panagiotis , Sonnewald Ursula , Plaitakis Andreas , Schousboe Arne
Published: August 2002

Glutamate dehydrogenase (GDH) specific activities, kinetic properties and allosteric regulation were studied in extracts from cultured neurons and astrocytes prepared from mouse cerebral cortex and cerebellum. Considerable differences were observed in the specific activity of the enzyme among the different cell types with astrocytes expressing the highest GDH activity. This may reflect the functional importance of these cells in glutamate uptake and metabolism. Among the neurons, the glutamatergic cerebellar granule cells showed a GDH specific activity that was 60% higher (P < 0.01) than that of the GABAergic cerebral cortical neurons. Also, the Km for ammonia was 1.7‐fold higher in the cortical neurons than in the other cell types. These findings may reflect a particular need for the glutamatergic granule cells to synthesize glutamate via the GDH pathway. No differences were observed among the different cell types with regard to the allosteric properties of GDH expressed by these cells. © 2001 Wiley‐Liss, Inc.
Elucidation of the quantitative significance of pyruvate carboxylation in cultured cerebellar neurons and astrocytes
Authors: Waagepetersen Helle S. , Qu Hong , Schousboe Arne , Sonnewald Ursula
Published: August 2002

Pyruvate carboxylation was studied in cerebellar astrocytes and granule neurons. The cells were incubated in medium containing [U‐13C]glucose (2.5 mM) and [U‐13C]lactate (1 mM) and varying amounts of 3‐nitropropionic acid (3‐NPA) plus/minus aspartate. 3‐NPA alone clearly stopped tricarboxylic acid (TCA) cycle activity at the succinate dehydrogenase step in both culture types as evidenced by a buildup of succinate. Labeling of aspartate and glutamate was abolished in neurons in the presence of 3‐NPA. In astrocytes, however, labeled glutamate and glutamine derived from pyruvate carboxylation was detected. Unchanged glucose and lactate metabolism in the absence of a functioning malate aspartate shuttle indicates the importance of the glycerol‐3‐phosphate shuttle in brain cells. To compensate for the loss of oxaloacetate in the presence of 3‐NPA, unlabeled aspartate (0.25 mM) was added. In this case [1,2‐13C] and [3,4‐13C]aspartate were observed in neurons but not in astrocytes. This labeling pattern in aspartate occurs after a full turn of the TCA cycle and thus indicates only partial inhibition by 3‐NPA in the neurons when aspartate is present. In astrocytes, however, aspartate derived from uniformly labeled pyruvate was observed clearly indicating pyruvate carboxylation. The present study has unequivocally demonstrated a quantitatively important pyruvate carboxylation in astrocytes but it was not possible to demonstrate the presence of such carboxylation in neurons. Based on the present results it may be safely concluded that neuronal pyruvate carboxylation is unlikely to be of quantitative significance. © 2001 Wiley‐Liss, Inc.
Cyclin‐dependent kinase 5 (cdk5) activation requires interaction with three domains of p35
Authors: Amin Niranjana D. , Albers Wayne , Pant Harish C.
Published: August 2002

Cyclin‐dependent kinase 5 (cdk5), in contrast to other members of the cyclin‐dependent kinase family, is not activated by cyclins but instead is activated by complexing with neuron‐specific activator molecules (p35, p39, and p67). The most effective activator of cdk5 both in vitro and in vivo is p35. We have taken a kinetic approach to study the interaction between p35, its various truncated forms, and cdk5 to understand better the mechanism of its activation. The cdk5 complexes formed with the truncated forms p25 and p21 produced similar maximum active kinase, whereas the cdk5 complexed with full‐length p35 and a further truncated form spanning amino acid residues from 138 to 291, with approximate molecular weight of 16 kDa (p16), produced slightly less (80%) activation than p25. P16 was the smallest fragment of p35 that produced activation equal to or greater than that of full‐length p35. By examination of further truncations of p16, we found that a small number of residues, 11 and 4 at the N‐ and C‐termini, respectively, of p16, are essential for cdk5 activation. Further truncation, removing both essential N‐ and C‐terminal domains, produces a peptide with markedly higher affinity for cdk5 compared with the peptides that retain either of these domains. Using these inactive truncated peptides as inhibitors, we examined the kinetics of activation. From these studies we conclude that activation involves at least three cdk5‐interacting domains, one located at each end of p16 and at least one located in a central domain. The cdk5 activation process is slow: The second‐order rate constant for p16 is about 1.2 μM−1 hr−1. On the basis of kinetic data, we suggest that cdk5 exists in two conformations. The inactive kinase conformation predominates in the absence of the activator. Activation occurs in two stages: a rapid and reversible interaction of cdk5 with its activator, which involves only one or two binding domains, followed by a slow stabilization of the active conformation as interaction with all three domains is achieved. Published 2002 Wiley‐Liss, Inc.
Lack of prion protein expression results in a neuronal phenotype sensitive to stress
Authors: Brown David R. , Nicholas Richard St.J. , Canevari Laura
Published: August 2002

The prion protein is a highly conserved glycoprotein expressed most highly in the synapse. Evidence has recently been put forward to suggest that the prion protein is an antioxidant. However, the functional importance of the prion protein has been disputed; it is claimed that mice genetically ablated to lack prion protein expression are normal and have no specific phenotype. We have reexamined the phenotype of prion protein knockout mice and found that there are multiple biochemical changes in the mice, including increased levels of nuclear factor NF‐κB and Mn superoxide dismutase, COX‐IV decreased levels of Cu/Zn superoxide dismutase activity, decreased p53, and altered melatonin levels. Additionally, cultured cells from these mice are more sensitive to a range of insults, all linked to increased neuronal sensitivity to oxidative stress. These results imply that prion protein knockout mice are more sensitive to oxidative stress and have an altered phenotype that must be taken into account when considering the additional effects of increased levels of proteins such as Doppel. The implication of these results is that the consequence of genetic ablation of genes must include biochemical analysis as well as analyses of possible developmental and behavioral changes. © 2002 Wiley‐Liss, Inc.
Expression of Concern: Transient expression of fluorescent tau proteins promotes process formation in PC12 cells: Contributions of the tau C‐terminus to this process
Authors: Yu Jiang‐Zhou , Kuret Jeff , Rasenick Mark M.
Published: August 2002

The neuronal microtubule‐associated protein tau promotes microtubule assembly and has been implicated in the development of axonal morphology. In this study, PC12 cells were transiently transfected with constructs coding fusion proteins of human tau with green fluorescent protein (GFP). Expression of tau constructs actively stabilized microtubules. Expression of the C‐terminus of tau can mimic this effect in living cells, though to a lesser extent because of the absence of the tau N‐terminus. However, tau colocalization with microtubules did not require the presence of the tau N‐terminus. Transient expression of tau (including tau24, a four‐repeat human tau isoform encoded in 383 residues, and tau23, human fetal tau isoform encoded in 352 residues) stimulated process formation in PC12 cells, and this occurred faster with tau24 than with tau23. The residues (residues 154–172 in tau23) that confer microtubule nucleation activity of tau in vitro are not required for tau‐directed process formation. However, when tau induces the formation of cellular processes in response to cortical breakdown by cytochalasin B, residues 154–172 must be present. Thus, it appears that tau may serve to promote cellular process outgrowth in cultured neuronal cells and that C‐terminus of tau is essential to this process. © 2002 Wiley‐Liss, Inc.
Differential neuropathological alterations in transgenic mice expressing α‐synuclein from the platelet‐derived growth factor and Thy‐1 promoters
Authors: Rockenstein Edward , Mallory Margaret , Hashimoto Makoto , Song David , Shults Clifford W. , Lang Ingrid , Masliah Eliezer
Published: August 2002

Accumulation of α‐synuclein has been associated with neurodegenerative disorders, such as Lewy body disease and multiple system atrophy. We previously showed that expression of wild‐type human α‐synuclein in transgenic mice results in motor and dopaminergic deficits associated with inclusion formation. To determine whether different levels of human α‐synuclein expression from distinct promoters might result in neuropathology mimicking other synucleopathies, we compared patterns of human α‐synuclein accumulation in the brains of transgenic mice expressing this molecule from the murine Thy‐1 and platelet‐derived growth factor (PDGF) promoters. In murine Thy‐1‐human α‐synuclein transgenic mice, this protein accumulated in synapses and neurons throughout the brain, including the thalamus, basal ganglia, substantia nigra, and brainstem. Expression of human α‐synuclein from the PDGF promoter resulted in accumulation in synapses of the neocortex, limbic system, and olfactory regions as well as formation of inclusion bodies in neurons in deeper layers of the neocortex. Furthermore, one of the intermediate expresser lines (line M) displayed human α‐synuclein expression in glial cells mimicking some features of multiple system atrophy. These results show a more widespread accumulation of human α‐synuclein in transgenic mouse brains. Taken together, these studies support the contention that human α‐synuclein expression in transgenic mice might mimic some neuropathological alterations observed in Lewy body disease and other synucleopathies, such as multiple system atrophy. © 2002 Wiley‐Liss, Inc.
Cannabinoid receptor agonist‐stimulated [35S]guanosine triphosphateγs binding in the brain of C57BL/6 and DBA/2 mice
Authors: Basavarajappa Balapal S. , Hungund Basalingappa L.
Published: August 2002

The two inbred strains of mice C57BL/6 (alcohol‐preferring) and DBA/2 (alcohol‐avoiding) mice have been shown to differ significantly in their preference for alcohol (EtOH). We have previously demonstrated the differences in the density and the affinity of cannabinoid (CB1) receptors in the brains of the two inbred C57BL/6 and DBA/2 mouse strains. In the present study, we investigated the CB1 receptor agonist‐stimulated guanosine‐5′‐O‐(3‐[35S]thio)‐triphosphate ([35S]GTPγS) binding in plasma membranes (PM) from C57BL/6 and DBA/2 mice. The results indicate that the net CP55,940‐stimulated [35S]GTPγS binding was increased with increasing concentrations of CB1 receptor agonists and GDP. The net CB1 receptor agonist (WIN55,212‐2 or HU‐210 or CP55,940)‐stimulated [35S]GTPγS binding was reduced significantly (–10% to –12%, P < 0.05) in PM from DBA/2 mice; no significant differences were observed in basal [35S]GTPγS binding among these strains. Nonlinear regression analysis of net CP55,940‐stimulated [35S]GTPγS binding showed that the Bmax of cannabinoid agonist‐stimulated binding was significantly reduced (–24%) in DBA/2 mice (Bmax = 12.43 ± 0.64 for C57BL/6 and 9.46 ± 0.98 pmol/mg protein for DBA/2; P < 0.05) without any significant changes in the G protein affinity. The pharmacological specificity of CP55,940‐stimulated [35S]GTPγS binding was examined with CB1 receptor antagonist SR141716A, and these studies indicated that CP55,940‐stimulated [35S]GTPγS binding was blocked by SR141716A, with a decrease in the IC50 values in the PM from the DBA/2 mouse strain. These results suggest that a signal transduction pathway(s) downstream from the CB1 receptor system may play an important role in controlling the voluntary EtOH consumption by these strains of mice. J. Neurosci. Res. 64:429–436, 2001. © 2001 Wiley‐Liss, Inc.
In vitro model of microglial deramification: Ramified microglia transform into amoeboid phagocytes following addition of brain cell membranes to microglia‐astrocyte cocultures
Authors: Bohatschek Marion , Kloss Christian U.A. , Kalla Roger , Raivich Gennadij
Published: August 2002

Changes in the morphology of ramified microglia are a common feature in brain pathology and culminate in the appearance of small, rounded, microglia‐derived phagocytes in the presence of neural debris. Here, we explored the effect of adding brain cell membranes on the morphology of αMβ2‐integrin (CD11b/CD18, CR3) positive microglia cultured on a confluent astrocyte substrate as an in vitro model of deramification. Addition of brain membranes led to a loss of microglial ramification, with full transformation to small, rounded, macrophages at 20–40 μg/ml. Time course studies showed a rapid response, with first effects at 1–3 hours, and full transformation at 24–48 hours. Removal of cell membranes and exchange of the culture medium led to a similarly rapid process of reramification. Comparison of cell membranes from different tissues at 20 μg/ml showed strong transforming effect for the brain, more moderate for kidney and liver, and very weak for spleen and skeletal muscle. Fluorescent labeling of brain membranes revealed uptake by almost all rounded macrophages, by a subpopulation of glial fibrillary acidic protein (GFAP)‐positive astrocytes, but not by ramified microglia. Phagocytosis of inert fluorobeads did not lead to a transformation into macrophages but their phagocytosis was inhibited by brain membranes, pointing to a saturable uptake mechanism. In summary, addition of brain cell membranes and their phagocytosis leads to a rapid and reversible loss of ramification. The differences in transforming activity from different tissues and the absence of effect from phagocytosed fluorobeads suggest, however, the need for a second stimulus following the phagocytosis of cell debris. J. Neurosci. Res. 64:508–522, 2001. © 2001 Wiley‐Liss, Inc.
Antibodies directed against rubella virus induce demyelination in aggregating rat brain cell cultures
Authors: Besson Duvanel Cécile , Honegger Paul , Matthieu Jean‐Marie
Published: August 2002

To link the presence of intrathecal virus‐specific oligoclonal immunoglobulin G (IgG) in multiple sclerosis patients to a demyelinating activity, aggregating rat brain cell cultures were treated with antibodies directed against two viruses, namely, rubella (RV) and hepatitis B (HB). Anti‐RV antibodies in the presence of complement decreased myelin basic protein concentrations in a dose‐dependent manner, whereas anti‐HB antibodies had no effect. A similar but less pronounced effect was observed on the enzymatic activity of 2′,3′‐cyclic nucleotide 3′‐phosphohydrolase, which is enriched in noncompact membranes of oligodendrocytes. These effects were comparable to those in cultures treated with antibodies directed against myelin oligodendrocyte glycoprotein (MOG), previously found to be myelinotoxic both in vitro and in vivo. Sequence homologies were found between structural glycoprotein E2 of RV and MOG, suggesting that demyelination was due to molecular mimicry. To support the hypothesis that demyelination was caused by anti‐RV IgG that recognized an MOG epitope, we found that anti‐RV antibodies depleted MOG in a dose‐dependent manner. Further evidence came from the demonstration that anti‐RV and anti‐MOG IgG colocalized on oligodendrocyte processes and that both revealed by Western blot a 28 kDa protein in CNS myelin, a molecular weight corresponding to MOG. These findings suggest that a virus such as RV exhibiting molecular mimicry with MOG can trigger an autoimmune demyelination. J. Neurosci. Res. 65:446–454, 2001. © 2001 Wiley‐Liss, Inc.
Ammonia‐induced production of free radicals in primary cultures of rat astrocytes
Authors: Murthy C.R.K. , Rama Rao K.V. , Bai Ge , Norenberg Michael D.
Published: August 2002

Elevated levels of ammonia in blood and brain result in derangement of cerebral function. Recently, lipid peroxidation and oxidative stress have been implicated in ammonia neurotoxicity. Because ammonia is primarily detoxified in astrocytes, we postulated that pathophysiological concentrations of ammonia might induce free radical formation in these cells. To test this hypothesis, we examined the extent of free radical production in primary cultures of astrocytes that had been preloaded with the fluorescent dye 5‐ (and 6‐)carboxy‐2′,7′‐dichlorodihydrofluorescein diacetate (DCFDA). DCFDA fluoresence was found to be increased in a dose‐dependent manner when astrocytes were exposed to 1, 5, and 10 mM NH4Cl. This phenomenon was transitory; it peaked at 2.5 min after exposure and declined subsequently. By 2 hr after treatment, DCFDA fluorescence was below control level. Addition of catalase or superoxide dismutase to 5 mM NH4Cl‐treated astrocytes reduced free radical formation. Pretreatment with 3 mM methionine sulfoximine, an inhibitor of glutamine synthetase, also suppressed free radical formation by 5 mM NH4Cl. The results of this study suggest that elevated concentrations of ammonia induce the formation of free radicals in astrocytes and that this process is associated with the synthesis of glutamine. We propose that astrocyte‐derived free radicals may be responsible for some of the pathophysiological changes associated with hyperammonemic conditions. J. Neurosci. Res. 66:282–288, 2001. © 2001 Wiley‐Liss, Inc.
Identification and characterization of neuronal precursors and their progeny from human fetal tissue
Authors: Piper David R. , Mujtaba Tahmina , Keyoung Hansoo , Roy Neeta S. , Goldman Steven A. , Rao Mahendra S. , Lucero Mary T.
Published: August 2002

We have examined primary human neuronal precursors (HNPs) from 18–22‐week‐old fetuses. We showed that E‐NCAM/MAP2/β‐III tubulin‐immunoreactive neuronal precursors divide in vitro and could be induced to differentiate into mature neurons in 2 weeks. HNPs did not express nestin and differentiated slowly compared to rodent neuronal restricted precursors (NRPs, 5 days). Immunocytochemical and physiological analyses showed that HNPs could generate a heterogeneous population of neurons that expressed neurofilament‐associated protein and various neurotransmitters, neurotransmitter synthesizing enzymes, voltage‐gated ion channels, and ligand‐gated neurotransmitter receptors and could fire action potentials. Undifferentiated and differentiated HNPs did not coexpress glial markers. Only a subset of cells that expressed GFP under the control of the Tα1 tubulin promoter was E‐NCAM/β‐III tubulin‐immunoreactive, indicating nonexclusive overlap between these two HNP cell populations. Overall, HNPs resemble NRPs isolated from rodent tissue and appear to be a neuronal precursor population. J. Neurosci. Res. 66:356–368, 2001. © 2001 Wiley‐Liss, Inc.
Me and us: differential relationships among goal‐setting training, efficacy and effectiveness at the individual and team level
Authors: Gibson Cristina B.
Published: August 2002

Efficacy‐effectiveness relationships were examined for individual nurses and nursing teams who were either trained or untrained in goal‐setting. At the individual level, positive direct relationships were demonstrated between self‐efficacy and effectiveness, between training and subsequent self‐efficacy, and between training and effectiveness. Initial self‐efficacy also moderated the training‐effectiveness relationship. Nurses low in initial self‐efficacy realized greater effectiveness gains from the training than did nurses high in initial self‐efficacy. At the team level, group efficacy was related to effectiveness, and training was related to subsequent group efficacy, but training was not related to effectiveness, and there were no moderation effects for initial group efficacy. Collective cognition and behavioral plasticity are potential explanations for different effects at the individual and team level and avenues for theory development and future research. Copyright © 2001 John Wiley & Sons, Ltd.
Re‐thinking burnout
Authors: Densten Iain L.
Published: August 2002

The conceptualization and psychometric properties of the Maslach Burnout Inventory (Maslach and Jackson, 1981) were examined by this study. A new structure of five burnout factors was identified using a sample of 480 Australian law enforcement managers. An examination of each item, along with single and confirmatory factor analyses supported both emotional exhaustion and the lack of personal accomplishment factors splitting into two factors while depersonalization remained a single factor. The new five‐factor structure incorporates psychological and somatic strain aspects of emotional exhaustion, and two aspects of the lack of personal accomplishment, namely self and others. This expanded factor structure clarifies the multi‐dimensional nature of the MBI. Further research directions are discussed. Copyright © 2001 John Wiley & Sons, Ltd.
The good soldier: who is s(he)?
Authors: Kidder Deborah L. , Parks Judi McLean
Published: August 2002

This paper examines how perceptions of Organizational Citizenship Behaviors (OCBs) are affected by socially constructed gender roles. We argue that gender roles are important for the perception, categorization, and consequences of OCBs. We suggest that the dimensions of OCBs (altruism, courtesy, sportsmanship, and civic virtue) are related to gender stereotypes. Combining social identity theory with gender role theory suggests that the ‘gender’ of these behaviors, the job, the job incumbent, and the gender identity of the observer interact, potentially broaden the breadth of requisite job behaviors defined as either in‐ or extra‐role. Implications are discussed. Copyright © 2001 John Wiley & Sons, Ltd.
Multi‐wave, multi‐variable models of job insecurity: applying different scales in studying the stability of job insecurity
Authors: Mauno Saija , Leskinen Esko , Kinnunen Ulla
Published: August 2002

The study had two specific targets: first, to examine the stability of job insecurity by utilizing three‐year longitudinal data (n = 109) collected in Finland and, second, to clarify psychometric properties of four job insecurity scales, i.e., the global scale, the importance scale, the probability scale and the powerlessness scale. The study was carried out by means of questionnaires, which were answered on three occasions. Analyses were conducted using multi‐wave, multi‐variable models which were estimated and tested via the LISREL program. Generally, the results showed that job insecurity remained relatively stable during the follow‐up period, although there were some variations in the stability as well as in the psychometric properties of the four job insecurity scales examined. More specifically, three of the scales studied showed good psychometric properties, whereas the probability scale could not be estimated longitudinally. Furthermore, working organization and time had effects on the level of job insecurity measured via the different scales. Copyright © 2001 John Wiley & Sons, Ltd.
Reflections on shared cognition
Authors: Cannon‐Bowers Janis A. , Salas Eduardo
Published: August 2002

The purpose of this paper is to highlight several fundamental questions that remain regarding shared cognition: (1) What must be ‘shared’? (2) What does ‘shared’ mean? (3) How should ‘shared’ be measured? and (4) What outcomes do we expect shared cognition to affect? A general and integrative description of these questions is provided. In addition, the value of shared cognition is discussed along with recommendations for future research. Copyright © 2001 John Wiley & Sons, Ltd.
Trends in extreme daily rainfall and temperature in Southeast Asia and the South Pacific: 1961–1998
Authors: Manton M.J. , Della‐Marta P.M. , Haylock M.R. , Hennessy K.J. , Nicholls N. , Chambers L.E. , Collins D.A. , Daw G. , Finet A. , Gunawan D. , Inape K. , Isobe H. , Kestin T.S. , Lefale P. , Leyu C.H. , Lwin T. , Maitrepierre L. , Ouprasitwong N. , Page C.M. , Pahalad J. , Plummer N. , Salinger M.J. , Suppiah R. , Tran V.L. , Trewin B. , Tibig I. , Yee D.
Published: August 2002

Trends in extreme daily temperature and rainfall have been analysed from 1961 to 1998 for Southeast Asia and the South Pacific. This 38‐year period was chosen to optimize data availability across the region. Using high‐quality data from 91 stations in 15 countries, significant increases were detected in the annual number of hot days and warm nights, with significant decreases in the annual number of cool days and cold nights. These trends in extreme temperatures showed considerable consistency across the region. Extreme rainfall trends were generally less spatially coherent than were those for extreme temperature. The number of rain days (with at least 2 mm of rain) has decreased significantly throughout Southeast Asia and the western and central South Pacific, but increased in the north of French Polynesia, in Fiji, and at some stations in Australia. The proportion of annual rainfall from extreme events has increased at a majority of stations. The frequency of extreme rainfall events has declined at most stations (but not significantly), although significant increases were detected in French Polynesia. Trends in the average intensity of the wettest rainfall events each year were generally weak and not significant. Copyright © 2001 Royal Meteorological Society
Pilot study of latewood‐width of conifers as an indicator of variability of summer rainfall in the North American monsoon region
Authors: Meko David M. , Baisan Christopher H.
Published: August 2002

The variability of the North American Monsoon System (NAMS) is important to the precipitation climatology of Mexico and the southwestern United States. Tree‐ring studies have been widely applied to climatic reconstruction in western North America, but as yet, have not addressed the NAMS. One reason is the need for highly resolved seasonal dendroclimatic information. Latewood‐width, the portion of the annual tree ring laid down late in the growing season, can potentially yield such information. This paper describes a pilot study of the regional summer precipitation signal in latewood‐width from a network of five Pseudotsuga menziesii chronologies developed in the heart of the region of NAMS influence in Arizona, USA. Exploratory data analysis reveals that the summer precipitation signal in latewood is strong, but not equally so over the full range of summer precipitation. Scatter in the relationship increases toward higher levels of precipitation. Adjustment for removal of inter‐correlation with earlywood‐width appears to strengthen the summer precipitation signal in latewood‐width. To demonstrate a possible application to climatic reconstruction, the latewood precipitation signal is modelled using a nonlinear model—a binary recursive classification tree (CT) that attempts to classify summers as dry or not dry from threshold values of latewood‐width. The model identifies narrow latewood‐width as an effective predictor of a dry summer. Of 14 summers classified dry by latewood‐width for the period 1868–1992, 13 are actually dry by the instrumental precipitation record. The results suggest that geographical expansion of coverage by latewood‐width chronologies and further development of statistical methods may lead to successful reconstruction of variability of the NAMS on century time scales. Copyright © 2001 Royal Meteorological Society
Diurnal characteristics of heavy precipitation according to weather type at an upland site in Scotland
Authors: Svensson Cecilia , Jakob Dörte , Reed Duncan W.
Published: August 2002

The diurnal characteristics of heavy 3 h and 24 h precipitation events exceeding a certain threshold (o‐called peak‐over‐threshold or POT events) were studied according to synoptic weather type. Hourly precipitation data for 1970–86 from Eskdalemuir, an upland site in southern Scotland, and the (daily) Mayes weather type classification for Scotland were used. Through cluster analysis, the weather types were divided into five groups according to the overall diurnal distribution of precipitation. Subsequently, 272 POTs for each duration were extracted and analysed using circular statistics. The diurnal distributions of the 3 h POTs were found to be significantly non‐uniform for four of the five weather type groups.

The 3 h POTs in the group that includes the Cyclonic weather type show a bimodal distribution with early‐morning and afternoon maxima. A bias towards increased temperatures and a shift in the wind direction suggest that early‐morning POTs may be caused mainly by warm fronts. This is consistent with warm fronts providing favourable conditions for orographic enhancement, which occurs predominantly during the early morning. The afternoon maximum may represent cold frontal precipitation enhanced by thermal convection. Because a cyclone passage generally involves a warm front followed by a cold front, 24 h POTs were found to start significantly more often in the first 4 h after midnight than during the rest of the day. Copyright © 2002 Royal Meteorological Society.
The redevelopment of a weather‐type classification scheme for North America
Authors: Sheridan Scott C.
Published: August 2002

Synoptic weather‐typing, or the classification of weather conditions into categories, is a useful tool for climate impact applications. Numerous procedures have been developed to accomplish this goal. Before the advent of high‐speed computers, manual methods were most common; more recently, more automated methods have come into wide use. Both types of classification have shortcomings; manual methods are time consuming and difficult to reproduce, whereas automated methods may not produce easily interpretable results. Several recent methods have incorporated the advantages of both methodologies into a hybrid scheme.

This paper describes the redevelopment of one such hybrid scheme, the Spatial Synoptic Classification (SSC). The SSC, originally developed in the mid‐1990s, classifies each day at a location into one of six weather types, or a transition. It has been utilized for several applications, from climate trends to human health. Despite its utility, it has several shortcomings, most notably a lower‐than‐desired match percentage among adjacent stations and a framework that only allows for classification during winter and summer.

The new SSC (SSC2) has been altered in several important ways. The most notable changes involve the procedure for selecting seed days, days that typify a particular weather type at a particular location. With the new procedures, the SSC can now produce weather‐type classifications year‐round, instead of only winter and summer. The spatial cohesiveness among stations has also been improved. The SSC has been expanded to include Canada, Alaska, and Hawaii in addition to the lower 48 US states. SSC calendars are now available for 327 stations with a mean length of 44.6 years, and are updated daily on a website.

This paper also presents an important application of the redesigned SSC. It has been used in several heat‐stress warning systems worldwide. The synoptic approach is considered to be superior to a traditional apparent temperature approach, as it considers more parameters in its holistic assessment. At each location, one or two of the weather types is associated with mortality levels significantly above the mean. Copyright © 2002 Royal Meteorological Society
Normal-coordinate structural decomposition and the vibronic spectra of porphyrins
Authors: SHELNUTT JOHN A.
Published: August 2002

The connection is made between macrocycle deformations obtained from normal-coordinate structural decomposition (NSD) and the vibronic molecular states and spectra of porphyrins. NSD is a procedure that provides a description of the time-averaged distortion of a porphyrin in terms of normal-coordinate displacements from a D4 h symmetric reference structure. Expressions for the optical absorption spectra with vibrational structure are developed with these NSD-determined deformations as parameters. Using these expressions, the effects of macrocycle distortion on the UV-vis absorption spectra of porphyrins are determined.
Luminescence properties of a cofacial dipalladium porphyrin dimer under argon and in the presence of dioxygen
Authors: BOLZE FRÉDÉRIC , GROS CLAUDE P. , HARVEY PIERRE D. , GUILARD ROGER
Published: August 2002

The preparation and luminescence properties of a dipalladium cofacial porphyrin dimer (DPA) Pd 2 (where DPA is the tetraanion of 1,8-bis(2,8,13,17-tetraethyl-3,7,12,18-tetramethylporphyrin-5-yl)anthracene) are reported and compared together with the photophysical behavior of the known monomeric (OEP)Pd and (TPP)Pd complexes. The effect of dioxygen in the presence and in the absence of the very bulky base, 1-t-butyl-5-phenylimidazole, is also investigated. The title dimer, (DPA) Pd 2, shows fluorescence and phosphorescence in the ps and ms time scale, respectively, with a global intensity lower than that of the porphyrin monomer analogues. The fluorescence sensitivity towards dioxygen quenching appears greater for the dipalladium complex than that of the monoporphyrin derivatives. In the presence of the bulky base, this sensitivity shows a dramatic decrease.
The Greenland 8200 cal. yr BP event detected in loss‐on‐ignition profiles in Norwegian lacustrine sediment sequences
Authors: Nesje Atle , Dahl Svein Olaf
Published: August 2002

High‐resolution loss‐on‐ignition analyses of lacustrine sediment cores from both proglacial and non‐glacial lakes in southern Norway have revealed a specific pattern characterised by a significant, two‐peaked reduction of the loss‐on‐ignition values in the basal half of the cores. In non‐glacier‐fed lakes, the loss‐on‐ignition variations are interpreted to reflect mainly lake productivity and hence variability in surface summer air temperature. Sediments deposited in proglacial lakes, however, reflect mainly the glacier activity in the lake catchment. Bulk AMS radiocarbon dates from the core sequences and the loss‐on‐ignition curve pattern suggest that this event correlates with the ‘8200 cal. yr BP event’ recorded in the GRIP and GISP2 Greenland ice‐cores, termed the Finse event in southern Norway. Copyright © 2001 John Wiley & Sons, Ltd.