bluuebunny/crossref_metadata_2025 huggingface dataset:
Fast imaging of phosphocreatine in the normal human myocardium using a three‐dimensional RARE pulse sequence at 4 Tesla
Authors: Greenman Robert L. , Axel Leon , Ferrari Victor A. , Lenkinski Robert E.
Published: August 2002

Purpose

To investigate the use of a three‐dimensional rapid acquisition with relaxation enhancement (RARE) pulse sequence for direct acquisition of phosphocreatine (PCr) images of the human myocardium.

Materials and Methods

A short elliptical birdcage radiofrequency (RF) body coil was constructed to produce a uniform flip angle throughout the chest cavity. In vivo images using a spectrally‐selective RARE sequence with a spatial resolution of 1.2 cm × 1.2 cm × 2.5 cm (4 cm3) were acquired in nine minutes and 40 seconds.

Results

Scans of phantoms demonstrated excellent spectral selectivity. The signal‐to‐noise ratio in the myocardium ranged from 12.6 in the anterior wall to 5.3 in the mid septum.

Conclusion

This study demonstrates that PCr data can be acquired using a three‐dimensional RARE sequence with greater spatial and temporal resolution than spectroscopic techniques. J. Magn. Reson. Imaging 2002;15:467–472. © 2002 Wiley‐Liss, Inc.
Magnetic resonance image registration in multiple sclerosis: Comparison with repositioning error and observer‐based variability
Authors: Tan I Leng , van Schijndel Ronald A. , van Walderveen Marianne A.A. , Quist Marcel , Bos Reinhard , Pouwels Petra J.W. , Desmedt Pol , Adèr Herman J. , Barkhof Frederik
Published: August 2002

Purpose

To study the use of image registration in the analysis of multiple sclerosis (MS) lesion volume and compare this with repositioning error and observer‐based variability.

Materials and Methods

The normalized mutual information (NMI) algorithm is evaluated in an accuracy study using a phantom, followed by a validation study on magnetic resonance (MR) data of MS patients. Further, using scan‐rescan MR data, the effect of registration on MS lesion volume compared with repositioning error and observer‐based variability is assessed.

Results

The registration accuracy was near perfect in the phantom study, while the in vivo validation study demonstrated an accuracy on the order of 0.2–0.3 mm. In the scan‐rescan study, quantification accounted for 15.6% of the relative variance, repositioning for 44.4%, and registration for 40.0%.

Conclusion

NMI resulted in robust and accurate alignment of MR brain images of MS patients. Its use in the detection of changes in MS using large serial MR imaging (MRI) data warrants future evaluation. J. Magn. Reson. Imaging 2002;15:505–510. © 2002 Wiley‐Liss, Inc.
Mass spectrometric studies of anomeric glycopyranosyl azides
Authors: Dinya Zoltán , Benke Péter , Györgydeák Zoltán , Somsák László , Jekö József , Pintér István , Kuszman János , Praly Jean‐Pierre
Published: August 2002

We studied the mass spectrometric behaviour of peracetylated and underivatized anomeric hexopyranosyl azides and 5‐thioglucopyranosyl azides by means of different mass spectrometric techniques. The unstable molecular ions fragment predominantly by losing either N3 radical or N2 molecule. Loss of N2 molecule and the protonation of the derived nitrene were characteristic of the studied compounds. The presence of BF3·Et2O in the ion source is favorable for producing the protonated nitrene form. The protonated nitrene shows a new type of ring expansion rearrangement. The abundances of the [M + H − N2]+ ion makes it possible to identify the anomeric configuration of the azido group. Copyright © 2001 John Wiley & Sons, Ltd.
International Mass Spectrometry Society (IMSS)
Authors: Cooks R. G. , Gelpi E. , Nibbering N. M. M.
Published: August 2002

This paper gives a brief description of the recently formalized International Mass Spectrometry Society (IMSS). It is presented here in order to increase awareness of the opportunities for collaboration in mass spectrometry in an international context. It also describes the recent 15th International Mass Spectrometry Conference, held August/September 2000, in Barcelona. Each of the authors is associated with the IMSS. The 15th Conference, which covers all of mass spectrometry on a triennial basis, was chaired by Professor Emilio Gelpi of the Instituto de Investigaciones Biomedicas, Barcelona. The outgoing and founding President of the IMSS is Professor Graham Cooks, Purdue University, and the incoming President is Professor Nico Nibbering, University of Amsterdam. Similar material has been provided to the Editors of other journals that cover mass spectrometry. Copyright © 2001 John Wiley & Sons, Ltd.
Sequencing cyclic peptide inhibitors of mammalian ribonucleotide reductase by electrospray ionization mass spectrometry
Authors: Lin Shanhua , Liehr Sebastian , Cooperman Barry S. , Cotter Robert J.
Published: August 2002

Mammalian ribonucleotide reductase (mRR) is a potential target for cancer intervention. A series of lactam‐bridged cyclic peptide inhibitors (1–9) of mRR have been synthesized and tested in previous work. These inhibitors consist of cyclic and linear regions, causing their mass spectral characterization to be a challenge. We determined the fragmentation mechanism of cyclic peptides 1–9 using an ion‐trap mass spectrometer equipped with an ESI source. Low‐energy collision‐induced dissociation of sodiated cyclic peptides containing linear branches follows a general pathway. Fragmentation of the linear peptide region produced mainly a and b ions. The ring peptide region was more stable and ring opening required higher collision energy, mainly occurring at the amide bond adjacent to the lactam bridge. The sodium ion, which bound to the carbonyl oxygen of the lactam bridge, acted as a fixed charge site and directed a charge‐remote, sequence‐specific fragmentation of the ring‐opened peptide. Amino acid residues were cleaved sequentially from the C‐terminus to the N‐terminus. Our findings have established a new way to sequence cyclic peptides containing a lactam bridge based on charge‐remote fragmentation. This methodology will permit unambiguous identification of high‐affinity ligands within cyclic peptide libraries. Copyright © 2001 John Wiley & Sons, Ltd.
Characterisation of a South African human astrovirus as type 8 by antigenic and genetic analyses
Authors: Taylor Maureen B. , Walter Jolán , Berke Tamás , Cubitt W. David , Mitchell Douglas K. , Matson David O.
Published: August 2002

Human astroviruses (HAstV) can, on the basis of immunoassays using type‐specific rabbit antisera, be classified into eight serotypes that correlate with genotypes. Very few isolates of HAstV type 8 have been described and there is a paucity of data available with regard to the antigenic and genetic relationships between HAstV type 8 (HAstV‐8) and HAstV types 1 (HAstV‐1) to 7 (HAstV‐7). A wild‐type HAstV from a South African paediatric patient with diarrhoea was analysed antigenically, by immune electron microscopy and enzyme immunoassay, and genetically in selected regions of the ORF1a, ORF1b and ORF2 and characterised as a HAstV‐8. This HAstV‐8 strain exhibited greatest homology with HAstV‐4 in the 5′ end of the capsid gene and ORF1a and 1b, and greatest homology with HAstV‐5 in the 3′ end of the capsid region. This study confirms, by both antigenic and genetic analyses, that HAstV‐8 represents a distinct antigenic and genotype and is the first report of a HAstV‐8 from a hospitalised paediatric patient with diarrhoea in southern Africa. J. Med. Virol. 64:256–261, 2001. © 2001 Wiley‐Liss, Inc.
Replicative fitness in vivo of HIV‐1 variants with multiple drug resistance‐associated mutations
Authors: Devereux Helen L. , Emery Vincent C. , Johnson Margaret A. , Loveday Clive
Published: August 2002

The relative fitness of HIV‐1 viral variants containing a broad range of drug resistance‐associated mutations has been little studied in vivo. Understanding the relative fitness associated with viruses containing mutations may aid future therapeutic management. The aim of this study was to investigate the relative fitness of mutant viruses by assessing a cohort of patients who had developed resistance to many drugs and subsequently stopped all therapy. Eleven patients were assessed for drug resistance associated mutations in the protease (PR) and reverse transcriptase (RT) genes before and, at multiple time points, after stopping therapy. Relative fitness was calculated as a function of the rate of disappearance of mutant viruses when therapy was stopped. The least fit viruses were associated with the RT mutation M184I/V (11.6% less fit) and the PR mutations D30N (12.4% less fit) and M46I/L (21% less fit). Mutations at these codons were associated with significant reductions in fitness levels compared to wild‐type viruses. Mutations at codons 10, 20, 36, and 63 in the PR gene remained fairly constant when therapy was stopped and may not significantly reduce viral fitness. The rapid re‐population of wild‐type viruses may allow the recycling of antiretroviral drugs prescribed previously. J. Med. Virol. 65:218–224, 2001. © 2001 Wiley‐Liss, Inc.
Human picornavirus and coronavirus RNA in nasopharynx of children without concurrent respiratory symptoms
Authors: Nokso‐Koivisto Johanna , Kinnari Teemu J. , Lindahl Päivi , Hovi Tapani , Pitkäranta Anne
Published: August 2002

The prevalence of human rhino‐, entero‐, and coronaviruses was investigated by RT‐PCR in nasopharyngeal aspirates from 107 children without concurrent respiratory symptoms. The children were admitted to the hospital for elective surgery. The parents filled a questionnaire about the occurrence of respiratory symptoms four weeks before and two weeks after the surgery. The rate of viral detection was 45% in children with related past or recent respiratory infection whereas 20% of the samples taken from children without any related past or recent respiratory infections were positive for picornavirus RNA, P = 0.008. Thirty‐one (29%) of the nasopharyngeal aspirates were positive for viral RNA, 18% for rhinovirus, and 11% for enterovirus RNA. Coronavirus RNA was not found in any of the children. Fifty‐five percent of the children with virus‐positive samples had an infection‐related diagnosis. In addition, 81% of the children with virus‐positive samples had had previously respiratory symptoms or there were concurrent respiratory symptoms in other family members. Only four of the 31 virus‐positive samples were from children without infection‐related diagnosis or recent past (or immediate future) respiratory symptoms. J. Med. Virol. 66:417‐420, 2002. © 2002 Wiley‐Liss, Inc.
The ARB method
Authors: Lindenmeier Stefan , Russer Peter
Published: August 2002

For the general case of two interacting structures the computational effort of the adapting radiating boundaries (ARB) method is compared with the computational effort of the pure space discretizing transmission line matrix method. Since the numerical field modelling with the ARB method requires a very low computational effort, this method can be applied in a process for the automatical optimization of planar structures to prevent electromagnetic coupling phenomena. Numerical aspects of the method of ARB are shown. In two numerical examples, the ARB method is applied to the numerical modelling of the electromagnetic coupling between planar microwave structures. Copyright © 2001 John Wiley & Sons, Ltd.
Hepatocyte growth factor is a mitogen for olfactory ensheathing cells
Authors: Yan Henglin , Nie Xingtie , Kocsis Jeffery D.
Published: August 2002

Hepatocyte growth factor (HGF) is a potent mitogen for mature hepatocytes, and it has multi‐functional effects in a variety of cells in various organs. HGF stimulates DNA synthesis and promotes cell migration and morphogenesis in several cell types including the olfactory system. To characterize the potential mitogenic activity of HGF that might contribute to olfactory ensheathing cell (OEC) proliferation, we tested the ability of HGF to stimulate OEC division in vitro. OECs were obtained from adult rat olfactory bulbs and cultured in serum‐free medium, and were identified by double immunostaining for p75 and S‐100 antibodies. DNA synthesis assayed by pulsing BrdU for 24 hr showed that HGF at the concentration of 5–100 ng/ml elicited a 5–10‐fold increase of OEC proliferation. By immunocytochemical analysis, we demonstrated that c‐Met‐immunoreactivity was present in cultured OECs, and c‐Met anti‐serum significantly sequestered the activity of HGF on OECs proliferation, suggesting that HGF‐induced proliferation of OECs is mediated by the c‐Met receptor. The mitogenic activity of HGF was potentiated by addition of heregulin (HRG), but inhibited by addition of forskolin. These results demonstrate that HGF is a novel mitogen for rat OECs in vitro, and HGF/c‐Met system is involved in regulating OECs growth and development. J. Neurosci. Res. 66:698–704, 2001. © 2001 Wiley‐Liss, Inc.
Relationship between the increased cell surface α7 nicotinic receptor expression and neuroprotection induced by several nicotinic receptor agonists
Authors: Jonnala Ramamohana R. , Buccafusco Jerry J.
Published: August 2002

Nicotine and other nicotinic acetylcholine receptor agonists have been shown to exert neuroprotective actions in vivo and in vitro by an as yet unknown mechanism. Even the identification of the subtype of nicotinic receptor(s) mediating this action has not been determined. In neural cell lines, the induction of cytoprotection often requires exposure to nicotine for up to 24 hr to produce a full protective effect. One phenomenon associated with chronic exposure of neural cells to nAChR agonists is the increased expression of nAChRs (upregulation), possibly as a response to desensitization. Because nicotinic receptors desensitize rapidly in the continuous presence of agonist, we investigated whether the neuroprotective actions produced by different nicotinic receptor agonists was related to their ability to induce nicotinic receptor upregulation. Differentiated PC12 cells were preincubated for 24 hr with various nAChR ligands, and the cells were subsequently deprived of both NGF and serum to induce cytotoxicity. Under control conditions cell viability was reduced to 66.5 ± 5.4% of control by trophic factor withdrawal. For those cells pretreated with nicotine (1 nM–100 μM) cell viability increased from 74.2 ± 1.5 to 97.3 ± 4%. The neuroprotective action of nicotine was blocked by co‐treatment with either 5 μM mecamylamine or 10 nM methyllycaconitine (MLA). The high potency blockade by MLA suggested that neuroprotection was mediated through the α7 nicotinic receptor subtype. For the seven agonists examined for neuroprotective activity, only nicotine was capable of evoking a near maximal (near 100% cell viability) neuroprotective action. The next most effective group included epibatidine, 4OHGTS‐21, methycarbamylcholine, and 1,1‐dimethyl‐4‐phenyl‐piperazinium iodide. These least effective group included cytisine and tetraethylammonium. Incubation of differentiated PC12 cells with 10 μM nicotine increased the number of [125I]αbungarotoxin ([125I]αBGTbinding sites by 41% from 82.6 ± 3.67 to 117 ± 10.3 fmol/mg protein). Under similar conditions of incubation, the nicotinic receptor agonist cytisine (that was least effective in terms of neuroprotection) failed to increase the number of [125I]αBGT binding sites. Cells expressing increased levels of cell surface [125I]αBGT binding sites received added neuroprotective benefit from nicotine. Thus the induced upregulation of the α7 subtype of nicotinic receptors during chronic exposure to nicotine may be responsible for the drug's neuroprotective action. J. Neurosci. Res. 66:565–572, 2001. © 2001 Wiley‐Liss, Inc.
Altered brain phosphocreatine and ATP regulation when mitochondrial creatine kinase is absent
Authors: Kekelidze Téa , Khait Igor , Togliatti Anthony , Benzecry Jorge M. , Wieringa Be , Holtzman David
Published: August 2002

In cerebral gray matter, ATP concentration is closely maintained despite rapid, large increases in turnover and low substrate reserves. As seen in vivo by 31P nuclear magnetic resonance (NMR) spectroscopy, brain ATP is stable early in seizures, a state of high energy demand, and in mild hypoxia, a state of substrate deficiency. Like other tissues with high and variable ATP turnover, cerebral gray matter has high phosphocreatine (PCr) concentration and both cytosolic and mitochondrial creatine kinase (UbMi‐CK) isoenzymes. To understand the physiology of brain creatine kinases, we used 31P NMR to study PCr and ATP regulation during seizures and hypoxia in mice with targeted deletion of the UbMi‐CK gene. The baseline CK reaction rate constant (k) was higher in mutants than wild‐types. During seizures, PCr and ATP decreased in mutants but not in wild‐types. The k‐value for the CK catalyzed reaction rate increased in wild‐types but not in the mutants. Hypoxic mutants and wild‐types showed similar PCr losses and stable ATP. During recovery from hypoxia, brain PCr and ATP concentrations returned to baseline in wild‐types but were 20% higher than baseline in the mutants. We propose that UbMi‐CK couples ATP turnover to the CK catalyzed reaction rate and regulates ATP concentration when synthesis is increased. © 2001 Wiley‐Liss, Inc.
Role of specific aminotransferases in de novo glutamate synthesis and redox shuttling in the retina
Authors: LaNoue Kathyrn F. , Berkich Deborah A. , Conway Myra , Barber Alistair J. , Hu Lain‐Yen , Taylor Charles , Hutson Susan
Published: August 2002

In this study aminotransferase inhibitors were used to determine the relative importance of different aminotransferases in providing nitrogen for de novo glutamate synthesis in the retina. Aminooxyacetate, which inhibits all aminotransferases, blocked de novo glutamate synthesis from H14CO3− by more than 60%. Inhibition of neuronal cytosolic branched chain amino acid transamination by gabapentin or branched chain amino acid transport by the L‐system substrate analog, 2‐amino‐bicyclo‐(2,2,1)‐heptane‐2‐carboxylic acid, lowered total de novo synthesis of glutamate by 30%, suggesting that branched chain amino acids may account for half of the glutamate nitrogen contributed by transamination reactions. L‐cycloserine, an inhibitor of alanine aminotransferase, inhibited glutamate synthesis less than 15% when added in the presence of 5 mM pyruvate but 47% in the presence of 0.2 mM pyruvate. Although high levels of pyruvate blunted the inhibitory effectiveness of L‐cycloserine, the results indicate that, under physiological conditions, alanine as well as branched chain amino acids are probably the predominant sources of glutamate nitrogen in ex vivo retinas. The L‐cycloserine results were also used to evaluate activity of the malate/aspartate shuttle. In this shuttle, cytosolic aspartate (synthesized in mitochondria) generates cytosolic oxaloacetate that oxidizes cytosolic NADH via malate dehydrogenase. Because L‐cycloserine inhibits cytosolic but not mitochondrial aspartate aminotransferase, L‐cycloserine should prevent the utilization of aspartate but not its generation, thereby increasing levels of 14C‐aspartate. Instead, L‐cycloserine caused a significant decline in 14C‐aspartate. The results suggest the possibility that shuttle activity is low in retinal Müller cells. Low malate/aspartate shuttle activity may be the molecular basis for the high rate of aerobic glycolysis in retinal Müller cells. © 2001 Wiley‐Liss, Inc.
Identification and characterization of uptake systems for cystine and cysteine in cultured astrocytes and neurons: Evidence for methylmercury‐targeted disruption of astrocyte transport
Authors: Shanker Gouri , Aschner Michael
Published: August 2002

Maintenance of appropriate intracellular glutathione (GSH) levels is crucial for cellular defense against oxidative damage. A suggested mechanism of methylmercury (MeHg) neurotoxicity implicates the involvement of oxygen radical formation and a decrease in cellular levels of GSH. Astrocytes play an important role in providing GSH precursors to neurons, and as will be discussed in this review, altered GSH homeostasis likely leads to impairment of astrocytic handling of glutamate, and neuronal energy metabolism. The review summarizes recent observations on transport systems for cysteine and cystine, precursors of GSH, in primary cultures of astrocytes and neurons, and their sensitivity to MeHg treatment. © 2001 Wiley‐Liss, Inc.
α‐cyano‐4‐hydroxycinnamate decreases both glucose and lactate metabolism in neurons and astrocytes: Implications for lactate as an energy substrate for neurons
Authors: McKenna Mary C. , Hopkins Irene B. , Carey Adrienne
Published: August 2002

The rates of uptake and oxidation of [U‐14C]lactate and [U‐14C]glucose were determined in primary cultures of astrocytes and neurons from rat brain, in the presence and absence of the monocarboxylic acid transport inhibitor α‐cyano‐4‐hydroxycinnamate (4‐CIN). The rates of uptake for 1 mM lactate and glucose were 7.45 ± 1.35 and 8.80 ± 1.0 nmol/30 sec/mg protein in astrocytes and 2.36 ± 0.19 and 1.93 ± 0.16 nmol/30 sec/mg protein in neuron cultures, respectively. Lactate transport into both astrocytes and neurons was significantly decreased by 0.25–1.0 mM 4‐CIN; however, glucose uptake was not affected. The rates of 14CO2 formation from 1 mM lactate and glucose were 12.49 ± 0.77 and 3.42 ± 0.67 nmol/hr/mg protein in astrocytes and 29.32 ± 2.81 and 10.04 ± 1.79 nmol/hr/mg protein in neurons, respectively. Incubation with 0.25 mM 4‐CIN decreased the oxidation of lactate and glucose to 57.1% and 54.1% of control values in astrocytes and to 13.2% and 41.6% of the control rates in neurons, respectively. Preincubation with 4‐CIN further decreased the oxidation of both glucose and lactate. Studies with glucose specifically labeled in the one and six positions demonstrated that 4‐CIN decreased mitochondrial glucose oxidation but did not impair the metabolism of glucose via the pentose phosphate pathway in the cytosol. The lack of effect of 4‐CIN on glutamate oxidation demonstrated that overall mitochondrial metabolism was not impaired. These findings suggest that the impaired neuronal function and tissue damage in the presence of 4‐CIN observed in other studies may be due in part to decreased uptake of lactate; however, the effects of 4‐CIN on mitochondrial transport would significantly decrease the oxidative metabolism of pyruvate derived from both glucose and lactate. © 2001 Wiley‐Liss, Inc.
Constitutive overexpression of the basic helix‐loop‐helix Nex1/MATH‐2 transcription factor promotes neuronal differentiation of PC12 cells and neurite regeneration
Authors: Uittenbogaard Martine , Chiaramello Anne
Published: August 2002

Elucidation of the intricate transcriptional pathways leading to neural differentiation and the establishment of neuronal identity is critical to the understanding and design of therapeutic approaches. Among the important players, the basic helix‐loop‐helix (bHLH) transcription factors have been found to be pivotal regulators of neurogenesis. In this study, we investigate the role of the bHLH differentiation factor Nex1/MATH‐2 in conjunction with the nerve growth factor (NGF) signaling pathway using the rat phenochromocytoma PC12 cell line. We report that the expression of Nex1 protein is induced after 5 hr of NGF treatment and reaches maximal levels at 24 hr, when very few PC12 cells have begun extending neurites and ceased cell division. Furthermore, our study demonstrates that Nex1 has the ability to trigger neuronal differentiation of PC12 cells in the absence of neurotrophic factor. We show that Nex1 plays an important role in neurite outgrowth and has the capacity to regenerate neurite outgrowth in the absence of NGF. These results are corroborated by the fact that Nex1 targets a repertoire of distinct types of genes associated with neuronal differentiation, such as GAP‐43, βIII‐tubulin, and NeuroD. In addition, our findings show that Nex1 up‐regulates the expression of the mitotic inhibitor p21WAF1, thus linking neuronal differentiation to cell cycle withdrawal. Finally, our studies show that overexpression of a Nex1 mutant has the ability to block the execution of NGF‐induced differentiation program, suggesting that Nex1 may be an important effector of the NGF signaling pathway. © 2002 Wiley‐Liss, Inc.
Inhibition by R(+) or S(–) pramipexole of caspase activation and cell death induced by methylpyridinium ion or beta amyloid peptide in SH‐SY5Y neuroblastoma
Authors: Abramova Nicole A. , Cassarino David S. , Khan Shaharyar M. , Painter Terry W. , Bennett James P.
Published: August 2002

Cell models of neurodegenerative diseases (NDD) can involve expression of mutant nuclear genes associated with Mendelian forms of the diseases or effects of toxins believed to replicate essential disease features. Death produced by exposing neural cells to methylpyridinium ion (MPP+) or neurotoxic beta amyloid (BA) peptides is frequently used to study features of the sporadic, most prevalent forms of Parkinson's disease (PD) and Alzheimer's disease (AD), respectively. We examined in replicating SH‐SY5Y human neuroblastoma cells the release of cytochrome C into cytoplasm, activation of caspases 9 and 3, and loss of calcein retention as markers of the “mitochondrial” pathway of cell death. Exposure to 5 mM MPP+, which induces apoptotic cell death within 18–24 hr, released cytochrome C within 4 hr, activated caspases 9 and 3, and reduced calcein accumulation. BA 25–35 peptide produced more rapid and greater elevations of caspase 3 activity; no effects were observed with the nontoxic BA 35–25 reverse sequence. The dependence on mitochondrial transition pore (MTP) activity of MPP+‐induced caspase activations was demonstrated by preincubation with bongkreckic acid, which blocked elevations of caspases 9 and 3. Stereoisomers of pramipexole (PPX), a free radical scavenger and inhibitor of MTP opening, inhibited caspase activation (MPP+ and BA) and restored calcein accumulation (MPP+). Our results demonstrate that MPP+ and BA can induce cell death through MTP‐dependent activation of caspase cascades. PPX stereoisomers interfere with activation of these cell death pathways and may be useful clinically as neuroprotectants in PD and AD and related diseases. © 2002 Wiley‐Liss, Inc.
Gene transfer into the central nervous system in vivo using a recombinanat lentivirus vector
Authors: Lai Zhennan , Brady Roscoe O.
Published: August 2002

Gene transfer vectors derived from human immunodeficiency virus (HIV‐1) efficiently transduce nondividing cells and may provide for the delivery of their gene products to discrete regions of the brain. We investigated whether stable gene transduction can be achieved in cells of the central nervous system (CNS) in vivo by a potent lentivirus vector. The herpes simplex virus type 1 protein VP22 has been known to facilitate intercellular protein transport and thereby provides an opportunity to increase the effectiveness of therapeutic genes by enhancing the delivery of their protein products. We developed a lentiviral vector construct expressing enhanced green fluorescent protein (EGFP) fused at its N‐terminus to the herpes simplex virus VP22. In order to determine expression of the fusion protein in specific cells such as neurons in the CNS, a neuron‐specific promoter was also placed into the construct. The viral vectors were injected directly into the striatum and hippocampus of mouse brains. We found that the lentivirus vector efficiently and stably transduced nondividing cells in the CNS with transgene expression for over 3 months. We also show that the delivery of VP22‐EGFP fusion protein encoded by the lentivirus was effectively transported between neuronal cells via axons in vivo. Doubly labeled experiments revealed that our lentiviral vector is capable of delivering gene products to neurons and astrocytes in CNS. The data also demonstrate that up to 90% of the CNS cells transduced by our lentiviral vector under the control of the neuronal promoter are neurons. Published 2002 Wiley‐Liss, Inc.
Differential effects of glucocorticoids and gonadal steroids on glutathione levels in neuronal and glial cell systems
Authors: Schmidt A.J. , Krieg J.‐C. , Vedder H.
Published: August 2002

The aim of the present study was to investigate the short‐ and long‐term effects of glucocorticoids [corticosterone (CORT), dexamethasone (DEX), 6‐methylprednisolone (6‐MP)] and gonadal steroids [17β‐estradiol (E2), progesterone (PROG), testosterone (TEST)] on the levels of the antioxidant glutathione (GSH) in different cell systems of the CNS (neuronal hippocampal HT22 cells, primary hippocampal and neocortical brain cells, and C6 glioma cells). In HT22 cells, steroids exerted mainly long‐term effects. Significant increases of GSH levels were detectable after a 24 hr treatment with 10−7 M of DEX (122% ± 5%), 6‐MP (208% ± 32%), E2 (134% ± 10%), and TEST (155% ± 17%). A significant decrease occurred after incubation with PROG for 24 hr (79% ± 9%). In primary hippocampal cultures, a 24 hr treatment with DEX (140% ± 8%), E2 (123% ± 6%), and PROG (118% ± 5%) led to significant increases of the GSH levels, whereas, in neocortical primary cultures, only an incubation with E2 increased GSH (149% ± 8%). In C6 cells, hormone treatment led to both significant short‐term (1 hr: CORT 114% ± 5%, DEX 90% ± 3%, E2 88% ± 3%; 3 hr: DEX 115% ± 5%, E2 122% ± 6%, TEST 78% ± 4%) and significant long‐term (24 hr: CORT 74% ± 4%, 6‐MP 84% ± 5%, E2 115% ± 6%, PROG 91% ± 4%, TEST 116% ± 5%) effects. In summary, we were able to demonstrate differential effects of steroids on GSH levels in different cellular CNS models, showing an important influence of steroids and especially E2 on antioxidative cellular functions in neuronal and glial cells. © 2002 Wiley‐Liss, Inc.
Role of HuD and other RNA‐binding proteins in neural development and plasticity
Authors: Perrone‐Bizzozero Nora , Bolognani Federico
Published: August 2002

Transcription factors have traditionally been viewed as the main determinants of gene expression. Yet, in recent years it has become apparent that RNA‐binding proteins also play a critical role in determining the levels of expression of a large number of genes. Once mRNAs are transcribed, RNA‐binding proteins can control all subsequent steps in their function, from alternative splicing and translation to mRNA transport and stability. In the nervous system, a large number of genes are regulated post‐transcriptionally via the interaction of their mRNAs with specific RNA‐binding proteins. This type of regulation is particularly important in the control of the temporal and spatial pattern of gene expression during neural development. This review will discuss the function of the embryonic lethal abnormal vision (ELAV)/Hu family of nervous system‐specific RNA‐binding proteins, with a special emphasis on HuD, a member of this family that controls GAP‐43 mRNA stability and expression. In addition, we will present recent findings on other neural RNA‐binding proteins: the ribonucleoprotein K homology (KH)‐domain proteins, Fragile X mental retardation protein (FMRP), quakinguiable protein (QKI), and Nova‐1. Together with the ELAV/Hu family, these proteins are essential for proper neural development and in some cases for plasticity in the mature brain. The biological significance of these proteins is evident not only by their evolutionary conservation but also by the magnitude of problems arising from autoimmune reactions against them or from mutations affecting their expression or function. © 2002 Wiley‐Liss, Inc.
Identification of Gas6, a putative ligand for Sky and Axl receptor tyrosine kinases, as a novel neurotrophic factor for hippocampal neurons
Authors: Funakoshi Hiroshi , Yonemasu Tomoko , Nakano Toru , Matumoto Kunio , Nakamura Toshikazu
Published: August 2002

Sky (also known as “Tyro3” and “Rse”) is a member of the Axl/Sky/Mer receptor tyrosine kinase family and has two immunoglobulin‐like repeats and two fibronectin type III‐like repeats in the extracellular domain. Gas6 is a ligand for all members of the Axl family, each of which (Axl, Sky, and c‐Mer) has different affinities to Gas6. Physiological functions of Sky and Gas6 in the nervous system are not well understood, despite their importance, which is suggested by Sky structural features and its predominant expression in the brain. We found in the RNase protection assays that gas6 and sky mRNAs are expressed in the adult rat hippocampus and are similarly regulated during development. Expression levels were low during embryonic stages but gradually increased during development and reached the highest level in adulthood. Sky, but not Axl, immunoreactivity was observed in the adult hippocampus. Recombinant rat Gas6 attenuated hippocampal neuronal cell death that was caused by serum starvation in vitro, indicating that Gas6 is a novel neurotrophic factor for hippocampal neurons. Gas6 showed regulated expression in the sciatic nerve after nerve transection. Therefore, Sky and Gas6 have neurotrophic roles in the nervous system. © 2002 Wiley‐Liss, Inc.
Hypothermia and thiopentone sodium: Individual and combined neuroprotective effects on cortical cultures exposed to prolonged hypoxic episodes
Authors: Varathan Sriranganathan , Shibuta Satoshi , Shimizu Tomoaki , Varathan Vidya , Mashimo Takashi
Published: August 2002

Because there are many conflicting reports on cerebroprotective effects of hypothermia and barbiturates, we examined the degree of neuroprotection at defined temperatures (normothermia, 37°C; mild hypothermia, 32°C; deep hypothermia, 22°C; and profound hypothermia, 17°C) and various concentrations (low, 4 μM; moderate, 40 μM; and high, 400 μM) of thiopentone sodium (TPS), alone and in combination in cortical cultures exposed to prolonged hypoxia (24–48 hr). The survival rate of embryonic day (E)16 Wistar rat cortical neurons was evaluated on photomicrographs before and after experiments. During the 24‐hr hypoxic period, the survival rate of neurons was maximal with combinations of mild hypothermia with 40 μM (91.6 ± 0.7%) and 400 μM TPS (90.8 ± 0.7%) or deep hypothermia combined with all concentrations of TPS (4 μM, 90.6 ± 1.0%; 40 μM, 91.4 ± 0.8%; 400 μM, 91.8 ± 1.2%). During 48 hr hypoxia, the highest survival rate was seen with the combination of deep hypothermia and either 40 μM (90.9 ± 0.6%) or 400 μM (91.1 ± 1.4%) TPS. In the presence of profound hypothermia in combination with all concentrations of TPS, the survival rate was significantly reduced (P< 0.01) compared to combined application of either mild or deep hypothermia with TPS. In summary, maximal neuroprotection was attained with hypothermia and TPS in combination rather than applied individually, during prolonged hypoxic episodes (24– 48 hr). During a 24‐hr hypoxic period, both mild and deep hypothermia combined with a clinically relevant concentration of TPS (40 μM) offered the highest neuroprotection. Only deep hypothermia provided maximal neuroprotection when combined with 40 μM TPS, during 48‐hr hypoxia. Combination of profound hypothermia and TPS did not confer considerable neuroprotection during long lasting hypoxia. © 2002 Wiley‐Liss, Inc.
Δ9‐tetrahydrocannabinol increases endogenous extracellular glutamate levels in primary cultures of rat cerebral cortex neurons: Involvement of CB1 receptors
Authors: Tomasini Maria Cristina , Ferraro Luca , Bebe Berta Wonjie , Tanganelli Sergio , Cassano Tommaso , Cuomo Vincenzo , Antonelli Tiziana
Published: August 2002

The effects of the principal psychoactive component of marijuana, Δ9‐tetrahydrocannabinol (Δ9‐THC), on endogenous extracellular glutamate levels in primary cultures of rat cerebral cortex neurons were investigated. Locally applied Δ9‐THC (0.03, 3, 300, and 1,000 nM) concentration‐dependently increased basal extracellular glutamate levels (+18% ± 11%, +54% ± 10%, +90% ± 14%, +149% ± 33% vs. basal). The facilitatory effects of Δ9‐THC (3 and 300 nM) on cortical glutamate were fully counteracted in the presence of the selective CB1 receptor antagonist SR141716A (10 nM) and by replacement of the normal Krebs‐Ringer bicarbonate buffer with a low‐Ca2+ (0.2 mM) medium. Δ9‐THC application also induced an enhancement in K+‐evoked glutamate levels. These findings suggest that an increase in cortical glutamatergic transmission mediated by local CB1 receptor activation may underlie some of the psychoactive and behavioral effects of acute marijuana consumption. © 2002 Wiley‐Liss, Inc.
Hippocampal brain‐derived neurotrophic factor gene regulation by exercise and the medial septum
Authors: Berchtold Nicole C. , Kesslak J. Patrick , Cotman Carl W.
Published: August 2002

Brain‐derived neurotrophic factor (BDNF) enhances synaptic plasticity and neuron function. We have reported that voluntary exercise increases BDNF mRNA levels in the hippocampus; however, mechanisms underlying this regulation have not been defined. We hypothesized that medial septal cholinergic and/or gamma amino butyric acid (GABA)ergic neurons, which provide a major input to the hippocampus, may regulate the baseline gene expression and exercise‐dependent gene upregulation of this neurotrophin. Focal lesions were produced by medial septal infusion of the saporin‐linked immunotoxins 192‐IgG‐saporin or OX7‐saporin. 192‐IgG‐saporin produced a selective and complete loss of medial septal cholinergic neurons with no accompanying GABA loss. Baseline BDNF mRNA was reduced in the hippocampus of sedentary animals, but exercise‐induced gene upregulation was not impaired, despite complete loss of septo‐hippocampal cholinergic afferents. OX7‐saporin produced a graded lesion of the medial septum characterized by predominant GABA neuron loss with less reduction in the number of cholinergic cells. OX7‐saporin lesion reduced baseline hippocampal BDNF mRNA and attenuated exercise‐induced gene upregulation, in a dose‐dependent manner. These results suggest that combined loss of septal GABAergic and cholinergic input to the hippocampus may be important for exercise‐dependent BDNF gene regulation, while cholinergic activity on its own is not sufficient. These results are discussed in relation to their implications for aging and Alzheimer's disease. © 2002 Wiley‐Liss, Inc.
Altered apolipoprotein D expression in the brain of patients with Alzheimer disease
Authors: Belloir Bénédicte , Kövari Enikö , Surini‐Demiri Maria , Savioz Armand
Published: August 2002

The etiology of late‐onset Alzheimer disease is poorly understood. Predisposing factors such as the apolipoprotein E4 allele, as well as protective factors (e.g., antioxidants) have been proposed to play a role in the disease's process. A search for predisposing factors contributing to sporadic late‐onset Alzheimer disease was initiated using the differential display technique. RNA expression profiles of the entorhinal cortex and the cerebellum of Alzheimer‐diseased and normal patients were compared. The entorhinal cortex is the first brain region to accumulate neurofibrillary tangles during disease progression, whereas the cerebellum is spared. In the Alzheimer cases of this study, one signal showing preferential expression in the entorhinal cortex corresponded to the apolipoprotein D gene. This preferential expression might be genuine at the RNA level as suggested by the in situ hybridization method used. In addition, immunohistochemical experiments showed higher percentages of Apolipoprotein D reactive pyramidal neurons in the entorhinal cortex and region 1 of Ammon's horn in diseased patients. This increase correlated with the number of neurofibrillary tangles in Alzheimer as well as in normal patients. Colocalization of Apolipoprotein D proteins and neurofibrillary tangles in the same neuron was rare. Thus, these results suggest that in Alzheimer disease and aging, apolipoprotein D gene expression is increased in stressed cortical neurons before they possibly accumulate neurofibrillary tangles. J. Neurosci. Res. 64:61–69, 2001. © 2001 Wiley‐Liss, Inc.
Conduction of impulses by axons regenerated in a Schwann cell graft in the transected adult rat thoracic spinal cord
Authors: Pinzon Alberto , Calancie Blair , Oudega Martin , Noga Brian R.
Published: August 2002

Central nervous system axons regenerate into a Schwann cell implant placed in the transected thoracic spinal cord of an adult rat. The present study was designed to test whether these regenerated axons are capable of conducting action potentials. Following the transection and removal of a 4‐ to 5‐mm segment of the thoracic spinal cord (T8–T9), a polymer guidance channel filled with a mixture of adult rat Schwann cells and Matrigel was grafted into a 4‐ to 5‐mm‐long gap in the transected thoracic spinal cord. The two cut ends of the spinal cord were eased into the guidance channel openings. Transected control animals received a channel containing Matrigel only. Three months after implantation, electrophysiological studies were performed. Tungsten microelectrodes were used for monopolar stimulation of regenerated axons within the Schwann cell graft. Glass microelectrodes were used to record responses in the spinal cord rostral to the stimulation site. Evoked responses to electrical stimulation of the axon cable were found in two out of nine Schwann cell‐grafted animals. These responses had approximate latencies in the range of those of myelinated axons. No responses were seen in any of the Matrigel‐grafted animals. Histological analysis revealed that the two cases that showed evoked potentials had the largest number of myelinated axons present in the cable. This study demonstrates that axons regenerating through Schwann cell grafts in the complete transected spinal cord can produce measurable evoked responses following electrical stimulation. J. Neurosci. Res. 64:533–541, 2001. © 2001 Wiley‐Liss, Inc.
Identification of living oligodendrocyte developmental stages by fractal analysis of cell morphology
Authors: Bernard Frédéric , Bossu Jean‐Louis , Gaillard Stéphane
Published: August 2002

The Mandelbrot's fractal dimension (D), a measure of shape complexity, has been used to quantify the complex morphology of living cells. Previous studies on glial cells have shown that as cells increase in morphological complexity, their “D” value increases, suggesting that “D” could be used to estimate their stage of differentiation. In the present study the box‐counting method was used to calculate the “D” values of rat cerebellar oligodendrocytes during their differentiation in primary culture. These values were correlated with the immunoreactivity of cells to antigenic markers commonly used for assessing their stages of differentiation: A2B5, O4 and anti‐galactocerebroside (Gal‐C). Our results show that changes of the fractal dimension during differentiation follow the well known pattern of markers expression by these cells. These results demonstrate that A2B5‐, O4‐, and Gal‐C‐expressing oligodendrocytes can be confidently estimated from their respective fractal dimension values. Based on this immunocytochemical calibration, the calculation of “D” allows an easy and fast determination of the developmental stage of living (unstained) oligodendrocytes before the study of their physiological characteristics. Using this method we precisely identified living oligodendrocyte progenitors and early pro‐oligodendrocytes expressing voltage‐activated sodium currents that is a common characteristic of these two immature developmental stages (Sontheimer et al. [1989b] Neuron 2:1135–1145). J. Neurosci. Res. 65:439–445, 2001. © 2001 Wiley‐Liss, Inc.
Type of employment, work–family conflict and well‐being: a comparative study
Authors: Parasuraman Saroj , Simmers Claire A.
Published: August 2002

The study examined the impact of work and family role characteristics on work–family conflict, and indicators of psychological well being among self‐employed and organizationally employed women and men. Results show that employment type and gender have independent main effects on several of the study variables. Self‐employed persons enjoy greater autonomy and schedule flexibility at work, and report higher levels of job involvement and job satisfaction than those employed in organizations. However, they also experience higher levels of work–family conflict, and lower family satisfaction than organizational employees. The findings suggest that there are trade‐offs between the costs and benefits of self‐employment, and that business ownership is not a panacea for balancing work and family role responsibilties. Directions for future research are discussed. Copyright © 2001 John Wiley & Sons, Ltd.
Job insecurity and crossover of burnout in married couples
Authors: Westman Mina , Etzion Dalia , Danon Esti
Published: August 2002

We investigated crossover of burnout between spouses in 98 married couples in an organization undergoing downsizing. Burnout was found to be associated with feelings of job insecurity, self‐control and social undermining. Using SEM, findings supported the crossover of burnout from husbands to wives and the impact of burnout on undermining behavior. They also supported the research hypothesis of a direct relationship between job insecurity and burnout among husbands but not among wives. Sense of control was found to have a negative impact on burnout and on the spouse's undermining behavior and a positive impact on the spouse's sense of control. Copyright © 2001 John Wiley & Sons, Ltd.
The interactive effects of procedural justice and exchange ideology on supervisor‐rated commitment
Authors: Witt L. A. , Kacmar K. Michele , Andrews Martha C.
Published: August 2002

Matched data collected from 143 employees and their immediate supervisors of a private sector organization indicated that employee perceptions of procedural justice were only related to supervisor‐rated affective commitment among employees with a strong exchange ideology. That is, individuals motivated by a fair exchange exhibited fewer affective commitment behaviors when they viewed the environment as unfair than when they perceived it to be fair. Individuals comparatively indifferent to a fair exchange did not alter their affective commitment behaviors regardless of the level of perceived environmental fairness. These results illustrate the importance of considering individual differences in exchange ideology when attempting to alter the work environment for the purpose of increasing commitment. Implications for research and management practice are presented. Copyright © 2001 John Wiley & Sons, Ltd.
Instrumental pressure observations and atmospheric circulation from the 17th and 18th centuries: London and Paris
Authors: Slonosky V.C. , Jones P.D. , Davies T.D.
Published: August 2002

Daily pressure observations recorded by William Derham (1657–1735) at Upminster, Essex (near London), from 1697 to 1706 and 1708 have been corrected, converted to modern units and the Gregorian calendar, and adjusted for homogeneity. These pressure readings have been compared with previously published contemporary observations from Paris, and the two sets of early instrumental data used to calculate a daily series of the pressure difference between Paris and London. Frequency analysis of the daily series reveals that reversals of the south–north pressure gradient and easterly winds were more common from 1697 to 1708 than during the 1990s. Monthly mean values of Paris–London pressure differences have been compared with previously published monthly mean reconstructed surface pressure maps and to a reconstructed North Atlantic Oscillation (NAO) index. There is a good agreement between the strength and direction of monthly mean flow between London and Paris estimated from the circulation maps and the sign and magnitude of the Paris–London westerly flow index, but the correlation between the Paris–London index, known to be a good proxy for European zonal circulation, and the reconstructed NAO index, is low (0.2). Correlations between the monthly mean Paris–London zonal circulation index and central England temperatures suggest a strong relationship during winter and late summer from 1697 to 1708. The meticulous daily instrumental observations and the monthly and seasonal climate descriptions of Derham, his collection of instrumental observations and climatic descriptions from contemporary observers throughout Europe, and his early theories on the causes of climate change make his publications a valuable source of information for studies on climate during the early instrumental period. It is hoped that more of Derham's papers related to weather and climate may eventually come to light. Copyright © 2001 Royal Meteorological Society.