bluuebunny/crossref_metadata_2025 huggingface dataset:
Differential regulation of protein expression, growth and apoptosis by natural and synthetic retinoids
Authors: Christine Pratt M.A. , Niu Minying , White Dawn
Published: October 2003

All‐transretinoic acid (ATRA) can down regulate the anti‐apoptotic protein Bcl‐2 and the cell cycle proteins cyclin D1 and cdk2 in estrogen receptor‐positive breast cancer cells. We show here that retinoids can also reduce expression of the inhibitor of apoptosis protein, survivin. Here we have compared the regulation of these proteins in MCF‐7 and ZR‐75 breast cancer cells by natural and synthetic retinoids selective for the RA receptors (RARs) α, β, and γ then correlated these with growth inhibition, induction of apoptosis and chemosensitization to Taxol. In both cell lines ATRA and 9‐cisRA induced the most profound decreases in cyclin D1 and cdk2 expression and also mediated the largest growth inhibition. The RARα agonist, Ro 40‐6055 also strongly downregulated these proteins although did not produce an equivalent decrease in S‐phase cells. Only ATRA induced RARβ expression. ATRA, 9‐cisRA and 4‐HPR initiated the highest level of apoptosis as determined by mitochondrial Bax translocation, while only ATRA and 9‐cisRA strongly reduced Bcl‐2 and survivin protein expression. Enumeration of dead cells over 96 h correlated well with downregulation of both survivin and Bcl‐2. Simultaneous retinoid‐mediated reduction of both these proteins also predicted optimal Taxol sensitization. 4‐HPR was much weaker than the natural retinoids with respect to Taxol sensitization, consistent with the proposed requirement for reduced Bcl‐2 in this synergy. Neither the extent of cell cycle protein regulation nor AP‐1 inhibition fully predicted the antiproliferative effect of the synthetic retinoids suggesting that growth inhibition requires regulation of a spectrum of RAR‐regulated gene products in addition even to pivotal cell cycle proteins. © 2003 Wiley‐Liss, Inc.
Sphingosine 1‐phosphate effect on endothelial cell PAF synthesis: Role in cellular migration
Authors: Bernatchez Pascal N. , Tremblay François , Rollin Simon , Neagoe Paul‐Eduard , Sirois Martin G.
Published: October 2003

Sphingosine 1‐phosphate (S1P) and vascular endothelial growth factor (VEGF) are two inflammatory mediators capable of promoting endothelial cell (EC) migration and angiogenesis. As VEGF inflammatory effect is mediated by the synthesis of endothelial platelet‐activating factor (PAF) which is also contributing to VEGF chemotactic activity, we wanted to assess if S1P can trigger PAF synthesis in EC and if S1P‐induced migration is PAF‐dependent. Treatment of bovine aortic EC (BAEC) with S1P (10−10–10−6 M) increased dose‐ and time‐dependently the synthesis of PAF by up to 3.3‐fold above the basal level, with a maximal amount of PAF detected at 20 min post‐stimulation. This biological response was attenuated by inhibiting p38 mitogen‐activated protein kinase (MAPK), cytosolic or secreted phospholipase A2 (cPLA2, sPLA2) activity, suggesting that p38 MAPK activation by S1P promotes the conversion of membrane phospholipids into PAF through the combined activation of cPLA2 and sPLA2. Interestingly, pretreatment of BAEC with extracellular PAF receptor antagonists (BN52021, 10−5 M and CV3988, 10−6 M) reduced by up to 42% the cellular migration induced by S1P (10−6 M). These data demonstrate the capacity of S1P to induce PAF synthesis, which contributes in part to S1P chemotactic activity. © 2003 Wiley‐Liss, Inc.
Rho exchange factor ECT2 is induced by growth factors and regulates cytokinesis through the N‐terminal cell cycle regulator‐related domains
Authors: Saito Shin'ichi , Tatsumoto Takashi , Lorenzi Matthew V. , Chedid Marcio , Kapoor Veena , Sakata Hiromi , Rubin Jeffrey , Miki Toru
Published: October 2003

The ECT2 protooncogene plays a critical role in cytokinesis, and its C‐terminal half encodes a Dbl homology‐pleckstrin homology module, which catalyzes guanine nucleotide exchange on the Rho family of small GTPases. The N‐terminal half of ECT2 (ECT2‐N) contains domains related to the cell cycle regulator/checkpoint control proteins including human XRCC1, budding yeast CLB6, and fission yeast Cut5. The Cut5‐related domain consists of two BRCT repeats, which are widespread to repair/checkpoint control proteins. ECT2 is ubiquitously expressed in various tissues and cell lines, but elevated levels of ECT2 expression were found in various tumor cell lines and rapidly developing tissues in mouse embryos. Consistent with these findings, induction of ECT2 expression was observed upon stimulation by serum or various growth factors. In contrast to other oncogenes whose expression is induced early in G1, ECT2 expression was induced later, coinciding with the initiation of DNA synthesis. To test the role of the cell cycle regulator/checkpoint control protein‐related domains of ECT2 in cytokinesis, we expressed various ECT2 derivatives in U2OS cells, and analyzed their DNA content by flow cytometry. Expression of the N‐terminal half of ECT2, which lacks the catalytic domain, generated cells with more than 4N DNA content, suggesting that cytokinesis was inhibited in these cells. Interestingly, ECT2‐N lacking the nuclear localization signals inhibited cytokinesis more strongly than the derivatives containing these signals. Mutational analyses revealed that the XRCC1, CLB6, and BRCT domains in ECT2‐N are all essential for the cytokinesis inhibition by ECT2‐N. These results suggest that the XRCC1, CLB6, and BRCT domains of ECT2 play a critical role in regulating cytokinesis. Published 2003 Wiley‐Liss, Inc.
Melatonin reduces fenton reaction‐induced lipid peroxidation in porcine thyroid tissue
Authors: Karbownik Małgorzata , Lewiński Andrzej
Published: October 2003

Free radicals and reactive oxygen species (ROS) participate in physiological and pathological processes in the thyroid gland. Bivalent iron cation (ferrous, Fe2+), which initiates the Fenton reaction (Fe2+ + H2O2 → Fe3+ + •OH + OH−) is frequently used to experimentally induce oxidative damage, including that caused by lipid peroxidation. Lipid peroxidation is involved in DNA damage, thus indirectly participating in the early steps of carcinogenesis. In turn, melatonin is a well‐known antioxidant and free radical scavenger. The aim of the study was to estimate the effect of melatonin on basal and iron‐induced lipid peroxidation in homogenates of the porcine thyroid gland. In order to determine the effect of melatonin on the auto‐oxidation of lipids, thyroid homogenates were incubated in the presence of that indoleamine in concentrations of 0.0, 0.00001, 0.0001, 0.001, 0.01, 0.1, 0.25, 0.5, 1.0, 2.5, or 5.0 mM. To study melatonin effects on iron‐induced lipid peroxidation, the homogenates were incubated in the presence of FeSO4 (40 μM) plus H2O2 (0.5 mM), and, additionally, in the presence of melatonin in the same concentrations as above. The degree of lipid peroxidation was expressed as the concentration of malondialdehyde + 4‐hydroxyalkenals (MDA + 4‐HDA) per mg protein. Melatonin, in a concentration‐dependent manner, decreased lipid peroxidation induced by Fenton reaction, without affecting the basal MDA + 4‐HDA levels. In conclusion, melatonin protects against iron + H2O2‐induced peroxidation of lipids in the porcine thyroid. Thus, the indoleamine would be expected to prevent pathological processes related to oxidative damage in the thyroid, cancer initiation included. © 2003 Wiley‐Liss, Inc.
Hepatic stellate cells uptake of retinol associated with retinol‐binding protein or with bovine serum albumin
Authors: Fortuna Vitor A. , Martucci Renata B. , Trugo Luiz C. , Borojevic Radovan
Published: October 2003

Retinol is stored in liver, and the dynamic balance between its accumulation and mobilization is regulated by hepatic stellate cells (HSC). Representing less than 1% total liver protein, HSC can reach a very high intracellular retinoid (vitamin‐A and its metabolites) concentration, which elicits their conversion from the myofibroblast to the fat‐storing lipocyte phenotype. Circulating retinol is associated with plasma retinol‐binding protein (RBP) or bovine serum albumin (BSA). Here we have used the in vitro model of GRX cells to compare incorporation and metabolism of BSA versus RBP associated [3H]retinol in HSC. We have found that lipocytes, but not myofibroblasts, expressed a high‐affinity membrane receptor for RBP–retinol complex (KD = 4.93 nM), and both cell types expressed a low‐affinity one (KD = 234 nM). The RBP–retinol complex, but not the BSA‐delivered retinol, could be dislodged from membranes by treatments that specifically disturb protein–protein interactions (high RBP concentrations). Under both conditions, treatments that disturb the membrane lipid layer (detergent, cyclodextrin) released the membrane‐bound retinol. RBP‐delivered retinol was found in cytosol, microsomal fraction and, as retinyl esters, in lipid droplets, while albumin‐delivered retinol was mainly associated with membranes. Disturbing the clathrin‐mediated endocytosis did not interfere with retinol uptake. Retinol derived from the holo‐RBP complex was differentially incorporated in lipocytes and preferentially reached esterification sites close to lipid droplets through a specific intracellular traffic route. This direct influx pathway facilitates the retinol uptake into HSC against the concentration gradients, and possibly protects cell membranes from undesirable and potentially noxious high retinol concentrations. © 2003 Wiley‐Liss, Inc.
Exact mass measurement on an electrospray ionization time‐of‐flight mass spectrometer: error distribution and selective averaging
Authors: Wu Jiejun , McAllister Heather
Published: October 2003

An automated, accurate and reliable way of acquiring and processing flow injection data for exact mass measurement using a bench‐top electrospray ionization time‐of‐flight (ESI‐TOF) mass spectrometer is described. Using Visual Basic programs, individual scans were selected objectively with restrictions on ion counts per second for both the compound of interest and the mass reference peaks. The selected ‘good scans’ were then subjected to two different data‐processing schemes (‘combine‐then‐center’ and ‘center‐then‐average’), and the results were compared at various ion count limit settings. It was found that, in general, the average of mass values from individual scans is more accurate than the centroid mass value of the combined (same) scans. In order to acquire a large number of good scans in one injection (to increase the sampling size for statistically valid averaging), an on‐line dilution chamber was added to slow down the typically rapid mass chromatographic peak decay in flow‐injection analysis. This simple addition worked well in automation without the need for manual sample dilution. In addition, by dissolving the reference compound directly into the mobile phase, manual syringe filling can be eliminated. Twenty‐seven samples were analyzed with the new acquisition and process routines in positive electrospray ionization mode. For the best method found, the percentage of samples with RMS error less than 5 ppm was 100% with repetitive injection data (6 injections per sample), and 95% with single injection data. Afterwards, 31 other test samples were run (with MW ranging from 310 to 3493 Da, 21 samples in ESI+ and 10 in ESI− mode) and processed with similar parameters and 100% of them were mass‐calculated to RMS error less than 5 ppm also. Copyright © 2003 John Wiley & Sons, Ltd.
Utilisation of electrospray time‐of‐flight mass spectrometry for solving complex fragmentation patterns: application to benzoxazinone derivatives
Authors: Bonnington L. S. , Barcelò D. , Knepper T. P.
Published: October 2003

In this paper we describe the application of electrospray time‐of‐flight mass spectrometry (ESI‐TOFMS) to structural elucidation of the fragment ions formed from a range of natural and synthetic allelochemical derivatives. The extensive mass spectrometric characterisation of ten non‐glucosylated benzoxazinone derivatives using this method is described here for the first time. The analytes include six naturally occurring 1,4‐benzoxazin‐3(4H)‐one derivatives, including the hydroxamic acids DIMBOA [2,4‐dihydroxy‐7‐methoxy‐2H‐1,4‐benzoxazin‐3(4H)‐one] and DIBOA [2,4‐dihydroxy‐2H‐1,4‐benzoxazin‐3(4H)‐one], lactams HBOA [2‐hydroxy‐2H‐1,4‐benzoxazin‐3(4H)‐one] and HMBOA [2‐hydroxy‐7‐methoxy‐2H‐1,4‐benzoxazin‐3(4H)‐one], benzoxazolinones BOA [benzoxazolin‐2(3H)‐one] and MBOA [6‐methoxy‐benzoxazolin‐2(3H)‐one] and four synthetic variations, 2′H‐DIBOA [4‐hydroxy‐2H‐1,4‐benzoxazin‐3(4H)‐one], 2′OMe‐DIBOA [2‐methoxy‐4‐hydroxy‐2H‐1,4‐benzoxazin‐3(4H)‐one], 2′H‐HBOA [2H‐1,4‐benzoxazin‐3(4H)‐one] and 2′OMe‐HBOA [2‐methoxy‐2H‐1,4‐benzoxazin‐3(4H)‐one]. Assignments of the mass spectral fragments were aided by elemental composition calculation results, comparison of structural analogues and background literature, and acquired knowledge regarding feasible structures for the compounds. The influence of substituents on the chemical reactivity of the compounds with respect to the observed MS behaviour over varying nozzle potentials is addressed and, through comparison of the structural analogues, generic fragmentation patterns have also been identified. Copyright © 2003 John Wiley & Sons, Ltd.
Gas‐phase polar [4+ + 2] cycloaddition with ethyl vinyl ether: a structurally diagnostic ion–molecule reaction for 2‐azabutadienyl cations
Authors: Meurer Eduardo C. , Sparrapan Regina , Eberlin Marcos N.
Published: October 2003

The intrinsic reactivity of eight gaseous, mass‐selected 2‐azabutadienyl cations toward polar [4+ + 2] cycloaddition with ethyl vinyl ether has been investigated by pentaquadrupole mass spectrometric experiments. Cycloaddition occurs readily for all the ions and, with the only exception of those from the N‐acyl 2‐azabutadienyl cations (N‐acyliminium ions), the cycloadducts are found to dissociate readily upon collision activation (CID) both by retro‐Diels‐Alder reaction and by a characteristic loss of an ethanol (46u) neutral molecule. Ethanol loss from the intact polar [4+ + 2] cycloadduct functions therefore as a structurally diagnostic test: 72 u neutral gain followed by 46 u neutral loss, i.e., as a combined ion–molecule reaction plus CID ‘signature’ for N‐H, N‐alkyl and N‐aryl 2‐azabutadienyl cations. The two N‐acyliminium ions tested are exceptional as they form intact cycloadducts with ethyl vinyl ether which dissociate exclusively by the retro‐Diels‐Alder pathway. Copyright © 2003 John Wiley & Sons, Ltd.
Direct analysis of drug candidates in tissue by matrix‐assisted laser desorption/ionization mass spectrometry
Authors: Reyzer Michelle L. , Hsieh Yunsheng , Ng Kwokei , Korfmacher Walter A. , Caprioli Richard M.
Published: October 2003

Matrix‐assisted laser desorption/ionization mass spectrometry (MALDI‐MS) has been used to directly analyze and image pharmaceutical compounds in intact tissue. The anti‐tumor drug SCH 226374 was unambiguously determined in mouse tumor tissue using MALDI‐QqTOFMS (QSTAR) by monitoring the dissociation of the protonated drug at m/z 695.4 to its predominant fragment at m/z 228.1. A second drug, compound A, was detected in slices of rat brain tissue following oral administration with doses ranging from 1–25 mg/kg. Quantitation of compound A from whole brain homogenates using routine high‐performance liquid chromatography/tandem mass spectrometry (HPLC/MS/MS) procedures revealed that concentrations of the drug in whole brain varied from a low of 24 ng/g to a high of 1790 ng/g. The drug candidate was successfully detected by MALDI‐QqTOF in samples from each dose, covering a range of approximately two orders of magnitude. In addition, good correlation was observed between the MALDI‐QqTOFMS intensities at each dose with the HPLC/MS/MS results. Thus the MALDI‐MS response is proportional to the amount of drug in tissue. Custom software was developed to facilitate the imaging of small molecules in tissue using the MALDI‐QqTOF mass spectrometer. Images revealing the spatial localization of SCH 226374 in tumor tissue and compound A in brain tissue were acquired. Copyright © 2003 John Wiley & Sons, Ltd.
Peptide cation‐radicals. A computational study of the competition between peptide NCα bond cleavage and loss of the side chain in the [GlyPhe‐NH2 + 2H]+• cation‐radical
Authors: Tureček František , Syrstad Erik A. , Seymour Jennifer L. , Chen Xiaohong , Yao Chunxiang
Published: October 2003

Cation‐radicals and dications corresponding to hydrogen atom adducts to N‐terminus‐protonated Nα‐glycylphenylalanine amide (Gly‐Phe‐NH2) are studied by combined density functional theory and Møller‐Plesset perturbational computations (B3‐MP2) as models for electron‐capture dissociation of peptide bonds and elimination of side‐chain groups in gas‐phase peptide ions. Several structures are identified as local energy minima including isomeric aminoketyl cation‐radicals, and hydrogen‐bonded ion‐radicals, and ylid‐cation‐radical complexes. The hydrogen‐bonded complexes are substantially more stable than the classical aminoketyl structures. Dissociations of the peptide NCα bonds in aminoketyl cation‐radicals are 18–47 kJ mol−1 exothermic and require low activation energies to produce ion‐radical complexes as stable intermediates. Loss of the side‐chain benzyl group is calculated to be 44 kJ mol−1 endothermic and requires 68 kJ mol−1 activation energy. Rice‐Ramsperger‐Kassel‐Marcus (RRKM) and transition‐state theory (TST) calculations of unimolecular rate constants predict fast preferential NCα bond cleavage resulting in isomerization to ion‐molecule complexes, while dissociation of the CαCH2C6H5 bond is much slower. Because of the very low activation energies, the peptide bond dissociations are predicted to be fast in peptide cation‐radicals that have thermal (298 K) energies and thus behave ergodically. Copyright © 2003 John Wiley & Sons, Ltd.
Fragmentation of tunichrome Sp‐1 is dominated by an unusual gas‐phase intramolecular rearrangement
Authors: Taylor Steven W. , Kassel Daniel B. , Tincu J. Andy , Craig A. Grey
Published: October 2003

Tunichrome Sp‐1 is a modified pentapeptide from the ascidian Styela plicata, having the structure H‐DOPA‐DOPA‐Gly‐Pro‐dcΔDOPA (where DOPA = 3,4‐dihydroxyphenylalanine and dcΔDOPA = decarboxy‐(E)‐α,β‐dehydro‐DOPA). The tandem mass spectrum of the peptide is dominated by a number of abundant fragment ions that involve a gas‐phase rearrangement where the dcΔDOPA group becomes covalently attached to the N‐terminus. The high degree of rearrangement in Sp‐1 compared with a related octapeptide, plicatamide, allowed for detailed multiple mass spectrometric (MSn) (up to n = 6) experiments, and hence permitted a detailed assessment of the origin and routes to the formation of the various rearrangement ions. Analyses on both a triple‐quadrupole and a quadrupole time‐of‐flight mass spectrometer were made to ascertain whether the gas‐phase rearrangements observed for tunichrome Sp‐1 were unique to an ion trap mass spectrometer (i.e. the hypothesis being that perhaps the extended trapping times were required to facilitate this unusual gas‐phase rearrangement). Interestingly, analyses on both the triple‐quadrupole and quadruple time‐of‐flight mass spectrometers revealed an identical phenomenon, with the rearrangement fragment ions present at approximately the same abundance as the non‐rearranged a‐, b‐ and y‐type sequence ions. We suggest that the smaller size of tunichrome Sp‐1 compared with plicatamide facilitates the transfer of the dcΔDOPA group in this gas‐phase rearrangement. This rearrangement was not observed for peptide analogs of tunichrome Sp‐1 that did not contain the dcΔDOPA at the C‐terminus, confirming that the presence of dcΔDOPA is critical for the rearrangement. Copyright © 2003 John Wiley & Sons, Ltd.
Connection between Eastern Mediterranean seasonal mean 500 hPa height and sea‐level pressure patterns and the spatial rainfall distribution over Israel
Authors: Zangvil Abraham , Karas Svetlana , Sasson Anat
Published: October 2003

This study introduces a new conceptual model to explain the recently observed changes in winter precipitation over Israel. The model is based on our earlier published work (where a connection was reported between the occurrence of major rain days (MRDs) in different parts of the country and three prototypes, A, B and C, of the 500 hPa trough axis orientation prevailing on MRDs) and on additional results obtained by an extension of that work in the present paper.

The first part of the present study is devoted to the extension of our early work. Composite techniques have been used on National Center for Atmospheric Research (NCAR)–National Meteorological Center grid‐point data for the rain seasons 1981–82 to 1985–86 to identify the sea‐level pressure (SLP) distribution associated with each of the three 500 hPa prototypes. Prototype A (trough axis oriented from northwest to southeast, earlier shown to be associated with MRDs in northern Israel) was found in the present work to be associated with a surface low in the vicinity of Antalya, southern Turkey. Prototype B (trough axis oriented from north to south, earlier shown to be associated with MRDs in central Israel) was found in the present work to be associated with a surface low over southeastern Turkey. Prototype C (trough axis oriented from northeast to southwest, earlier shown to be associated with MRDs in southern Israel) was found to be associated with elevated surface pressure over northwestern Turkey and a trough over eastern Turkey.

In the second part of the study we used our results to construct a conceptual model of the mechanism responsible for the relative increases in seasonal (winter) rainfall over the southern part of the country and the decrease over the north. Using National Centers for Environmental Prediction–NCAR reanalysis data for the period 1982–2000, we demonstrated that the direct atmospheric agent responsible for this change in the spatial rainfall distribution is an increased frequency of occurrence of 500 hPa troughs oriented from northeast to southwest (Prototype C) accompanied by prominent positive SLP anomalies centred over Turkey. Our analysis further shows that these atmospheric systems are consistent with the persistence of a positive phase of the North Atlantic Oscillation on the one hand and with latest IPCC predictions of precipitation patterns over the eastern Mediterranean basin on the other hand. Copyright © 2003 Royal Meteorological Society
Variability of the impact of El Niño–southern oscillation on sea‐level pressure anomalies over the North Atlantic in January to March (1874–1996)
Authors: Gouirand I. , Moron V.
Published: October 2003

Sea‐level pressure (SLP) anomalies over the North Atlantic and European (NAE) sector (25–70°N, 100°W–50°E) and over a larger domain encompassing the entire North Pacific domain are studied to demonstrate that SLP anomalies (SLPAs) during boreal winter (January–March) vary widely between years characterized by the same El Niño–southern oscillation (ENSO) phase. The typical cold ENSO signal tends to be more stable than the warm one during the 1874–1996 period. The typical cold ENSO pattern (e.g. positive SLPA south of 55°N across the North Atlantic and negative SLPA in the northern North Atlantic) is similar to the positive phase of the North Atlantic oscillation (NAO) and occurs throughout the 20th century, except during the 1950s and 1960s when the basinwide westerlies are particularly slow. On the contrary, the typical warm ENSO pattern (e.g. positive SLPA from central Canada to Scandinavia and negative SLPA from the southeastern USA to central Europe, corresponding to the negative phase of the NAO) occurs mainly from 1930 to 1970. Another robust warm ENSO pattern is associated with a large positive (negative) SLPA between Newfoundland and western Europe (between Greenland and Scandinavia), and occurs mainly at the beginning and the end of the 20th century when the basinwide North Atlantic westerlies are strengthened. All these patterns stay statistically significant when the multi‐decadal variability is removed from the North Atlantic SLPA. It is shown that the low‐frequency variability of the north tropical Atlantic sea‐surface temperature anomalies could exert a modulating effect on the ENSO teleconnection. NAE SLPAs tend to be strong during warm (cold) ENSO winters and consistent with a negative (positive) phase of the NAO when the north tropical Atlantic is anomalously warm (cold). Lastly, the magnitude of the SLPA patterns over the NAE sector appears poorly related to the intensity of sea‐surface temperature anomalies in the central and eastern equatorial Pacific. Copyright © 2003 Royal Meteorological Society
Tnfa and Il‐10 deficiencies have contrasting effects on lung tumor susceptibility: Gender‐dependent modulation of IL‐10 haploinsufficiency
Authors: Bernert Heike , Sekikawa Kenji , Radcliffe Richard A. , Iraqi Fuad , You Ming , Malkinson Alvin M.
Published: October 2003

Epidemiologic evidence suggests that pulmonary diseases with a prominent chronic inflammatory component elevate lung cancer risk. Genetic manipulations of mouse models of lung inflammation and tumorigenesis can be used to investigate this association. The genes encoding pro‐inflammatory tumor necrosis factor‐α (TNFα) and antiinflammatory IL‐10 cytokines map within quantitative trait loci that regulate susceptibility to lung tumor development in mice; sensitive A/J and resistant C57BL/6J (B6) mice have different Tnfa and Il‐10 alleles. Genetic ablation studies were performed to examine whether these genes would qualify as candidate tumor modifiers. Tnfa null (−/−) mice on a B6 background and B6.129 Il‐10−/− mice were intercrossed with A/J mice and subjected to urethane carcinogenesis; lung tumor multiplicity was determined 20 weeks later. In the absence of one copy of Tnfa, tumor number. Male Il‐10+/+ mice developed more tumors than did female mice (P < 0.001), absence of one copy of Il‐10 raised tumor number in female mice to that observed in +/+ males, but no change in multiplicity occurred in Il‐10 hemizygous males. Thus, a deficit of pro‐inflammatory TNFα decreased the number of tumors, whereas diminished gene copy number of anti‐inflammatory IL‐10 increased tumorigenesis; manifestation of an effect of Il‐10 haploinsufficiency is gender dependent. These studies support a role for inflammation in lung cancer susceptibility. © 2003 Wiley‐Liss, Inc.
Changes in gene expression during chemical‐induced nephrocarcinogenicity in the Eker rat
Authors: Patel Sonal K. , Ma Ning , Monks Terrence J. , Lau Serrine S.
Published: October 2003

Hydroquinone (HQ) is a rodent carcinogen and a potential human carcinogen. Glutathione conjugation of HQ enhances its biological reactivity, and 2,3,5‐tris‐(glutathion‐S‐yl)hydroquinone (TGHQ) is a potent nephrotoxicant and nephrocarcinogen in the Eker rat. Moreover, a single exposure of primary epithelial cells derived from Eker rat kidneys to TGHQ transforms these cells into an immortalized phenotype (quinol‐thioether transformed rat renal epithelial (QT‐RRE) cells). The Eker rat bears a mutation in one allele of the tuberous sclerosis‐2 (Tsc‐2) tumor suppressor gene, which predisposes the animals to the development of spontaneous and chemical‐induced renal cell carcinoma. Thus, the Eker rat provides a unique model for elucidating the mechanisms of renal tubular epithelial carcinogeneisis. cDNA microarray analysis of QT‐RRE3 cells and of tumor tissue derived from the kidneys of Eker rats treated with TGHQ revealed alterations (by threefold or greater) in the expression of a total of 80 genes. Fifteen percent of these genes exhibited similar expression patterns in both QT‐RRE cells and tumor tissue. The differentially expressed genes primarily participate in three major areas: (1) signal transduction or in the regulation of signal transduction (extracellular signal regulated kinase 2 (ERK2); protein kinase CK2; protein kinase B; c‐jun; NF‐κB; ras‐related GTPases; annexins), (2) stress response, tissue remodeling, and DNA repair (glutathione‐S‐transferases; procollagen c proteinase enhancer; plasminogen activator; tissue inhibitor of metalloprotease 3; apurinic/apyrimidic endonuclease), and (3) electron transport and energy homeostasis (cytochrome c oxidase subunits). The changes in the expression of many of these genes was confirmed by reverse transcription (RT)‐polymerase chain reactions (PCR) using primers specific for the differentially expressed genes. As an example, the annexin I and II genes, implicated in signal transduction, were highly induced in tumor tissue and also in dysplastic lesions isolated from the kidneys of rats treated chronically with TGHQ. The annexin I and II proteins were also upregulated in tumor tissue, which probably play an important role in TGHQ‐induced nephrocarcinogenesis. Moreover, in the present study, a tumorigenicity assay using athymic nude mice revealed that QT‐RRE cell lines formed tumors when injected in the subcutis of nude mice, providing evidence that the cells are malignantly transformed. Histopathological analysis further indicated that the tumors were composed of neoplastic cells, resembling renal carcinoma cells with varying degrees of atypia, with the presence of apoptotic and mitotic figures. © 2003 Wiley‐Liss, Inc.
Elevated levels of prostate‐specific antigen (PSA) in prostate cancer cells expressing mutant p53 is associated with tumor metastasis
Authors: Downing Sean , Bumak Clare , Nixdorf Sheri , Ow Kim , Russell Pamela , Jackson Paul
Published: October 2003

The underlying basis for rising levels of prostate‐specific antigen (PSA) in prostate cancer is not fully understood, but attention has turned to the possibility that loss of normal p53 function might be directly involved. We have investigated the relationship between p53 function and PSA expression using in vitro and in vivo approaches. Three prostate cancer–derived p53 mutants (F134L, M237L, R273H) were introduced into LNCaP prostate cancer cells and stable transfectants established. Expression of mutant p53 was demonstrated by Western blot analysis, inactivation of wtp53 function, and a loss of p53‐dependent responses to DNA damage induced by UV‐irradiation and cisplatin. Levels of PSA mRNA and secreted protein were determined by RT‐PCR and Western blotting, respectively. Serine protease activity was assessed using an esterase assay. In vivo effects of mutant p53 expression were examined after orthotopic implantation into prostates of nude mice. Expression of all p53 mutants was associated with elevated PSA mRNA and secreted PSA protein. In a representative line, mutant p53 was also associated with increased PSA protease‐like activity compared with a control line expressing wildtype p53. Overall PSA levels, and PSA levels in serum from mice bearing tumors derived from cells expressing mutant p53, were increased compared with levels in mice bearing tumors derived from control cells. In addition, the tumors derived from cells with mutant p53 had increased vascularization and induced lymph node metastases. These data provide in vitro and in vivo support for the notion that p53 mutations directly contribute to increased levels of serum PSA, and are associated with more aggressive tumors. © 2003 Wiley‐Liss, Inc.
Generalized diffusion tensor imaging and analytical relationships between diffusion tensor imaging and high angular resolution diffusion imaging
Authors: Özarslan Evren , Mareci Thomas H.
Published: October 2003

A new method for mapping diffusivity profiles in tissue is presented. The Bloch‐Torrey equation is modified to include a diffusion term with an arbitrary rank Cartesian tensor. This equation is solved to give the expression for the generalized Stejskal‐Tanner formula quantifying diffusive attenuation in complicated geometries. This makes it possible to calculate the components of higher‐rank tensors without using the computationally‐difficult spherical harmonic transform. General theoretical relations between the diffusion tensor (DT) components measured by traditional (rank‐2) DT imaging (DTI) and 3D distribution of diffusivities, as measured by high angular resolution diffusion imaging (HARDI) methods, are derived. Also, the spherical tensor components from HARDI are related to the rank‐2 DT. The relationships between higher‐ and lower‐rank Cartesian DTs are also presented. The inadequacy of the traditional rank‐2 tensor model is demonstrated with simulations, and the method is applied to excised rat brain data collected in a spin‐echo HARDI experiment. Magn Reson Med 50:955–965, 2003. © 2003 Wiley‐Liss, Inc.
Value of a blood pool contrast agent in MR venography of the lower extremities and pelvis: Preliminary results in 12 patients
Authors: Aschauer Manuela , Deutschmann Hannes A. , Stollberger Rudolf , Hausegger Klaus A. , Obernosterer Andrea , Schöllnast Helmut , Ebner Franz
Published: October 2003

The purpose of this study was to determine the value of a blood‐pool contrast media (NC100150, Nycomed Imaging (now Amersham Health) Oslo, Norway) for evaluation of venous thrombosis of the deep veins of the pelvis and lower extremities. Twelve patients were prospectively evaluated with conventional X‐ray venography (XRV) and MR venography (MRV) after injection of NC100150 (2 ml/kg body weight). The source images and 3D maximum intensity projection (MIP) were viewed on an independent workstation. Diagnosis was made in consensus from two radiologists. Diagnostic image quality was achieved in 87 veins with XRV and MRV. As determined by XRV, thrombus was present in 30 out of 87 veins (34.5%). There was agreement concerning absence or presence of thrombi in 83 out of 87 veins (95.4%; κ = 0.9 ± 0.05). Compared to XRV, overall sensitivity and specificity of blood‐pool MRV were 93.3% and 96.5%, respectively. Two venous thromboses of the popliteal and posterior tibial vein were diagnosed in MRV, but not in XRV. Conversely, two venous thromboses below the knee had been missed by MRV. NC100150 allows prolonged and improved visualization of the peripheral vasculature and may overcome some limitations of gadolinium contrast media. A more complete examination of the proximal venous tree may be possible than with conventional XRV. Arterial and venous enhancement and motion artifacts can limit image interpretation. Magn Reson Med 50:993–1002, 2003. © 2003 Wiley‐Liss, Inc.
Triggered, navigated, multi‐baseline method for proton resonance frequency temperature mapping with respiratory motion
Authors: Vigen Karl K. , Daniel Bruce L. , Pauly John M. , Butts Kim
Published: October 2003

A technique is presented for the acquisition of temperature maps in the presence of variable respiratory motion using the proton resonance frequency (PRF) shift. The technique uses respiratory triggering, diaphragm position determination with a navigator echo, and the collection of multiple baseline images to generate temperature maps. Laser ablations were performed in an ex vivo liver phantom undergoing variable simulated respiratory motion and in vivo in four porcine livers, demonstrating a reduction of artifacts in the computed temperature maps compared with conventional single baseline techniques, both uncorrected and corrected for motion. Magn Reson Med 50:1003–1010, 2003. © 2003 Wiley‐Liss, Inc.
Parsing local signal evolution directly from a single‐shot MRI signal: A new approach for fMRI
Authors: Twieg Donald B.
Published: October 2003

In this work a new single‐shot MRI method, single‐shot parameter assessment by retrieval from signal encoding (SS‐PARSE), is introduced. This method abandons a fundamental simplifying assumption that is used in conventional MRI methods. Established MRI methods implicitly assume that the local intrinsic signal does not change its amplitude or phase during signal acquisition, even though these changes may be substantial, especially during the relatively long signals used in single‐shot image acquisitions. SS‐PARSE, on the other hand, acknowledges local decay and phase evolution, and models each signal datum as a sample from (k,t)‐space rather than k‐space. Because of this more accurate signal model, SS‐PARSE promises improved performance in terms of accuracy and robustness, but requires more intensive reconstruction computations. The theoretical properties of the method are discussed, and simulation results are presented that demonstrate more robust and accurate measurements of relaxation rate changes associated with brain activation in functional MRI (fMRI), freedom from geometric errors due to off‐resonance frequencies, and better tolerance of the large susceptibility gradients that occur naturally in parts of the brain. In addition, this technique has the potential to assess nonexponential relaxation behavior during a single‐shot signal. Magn Reson Med 50:1043–1052, 2003. © 2003 Wiley‐Liss, Inc.
Breast tissue differentiation using arterial spin tagging
Authors: Zhu David C. , Buonocore Michael H.
Published: October 2003

An arterial spin tagging (AST) pulse sequence has been developed to measure T1 and relative blood perfusion. This full sequence is composed of three sequences: selective tagging, nonselective tagging, and nontagging. Perfusion quantification error resulting from imperfect inversion and acquisition slice profiles has been addressed in the literature. In this work, the error is reduced through the application of optimized Shinnar‐Le Roux (SLR) RF pulses and a semi‐log linear regression data‐processing technique. A threshold approach based on the breast tissue T1 and relative blood perfusion is introduced to show that these two parameters can be applied to breast tissue differentiation and potentially to cancer detection. Magn Reson Med 50:966–975, 2003. © 2003 Wiley‐Liss, Inc.
High‐resolution diffusion and relaxation‐edited magic angle spinning 1H NMR spectroscopy of intact liver tissue
Authors: Rooney O.M. , Troke J. , Nicholson J.K. , Griffin J.L.
Published: October 2003

High‐resolution magic angle spinning (HRMAS) 1H NMR spectroscopy is ideal for monitoring the metabolic environment within tissues, particularly when spectra are weighted by physical properties such as T1 and T2 relaxation times and apparent diffusion coefficients (ADCs). In this study, spectral‐editing using T1 and T2 relaxation times and ADCs at variable diffusion times was used in conjunction with HRMAS 1H NMR spectroscopy at 14.1 T in liver tissue. To enhance the sensitivity of ADC measurements to low molecular weight metabolites a T2 spin echo was included in a standard stimulated gradient spin‐echo sequence. Fatty liver induced in rats by chronic orotic acid feeding was investigated using this modified sequence. An increase in the combined ADC for the co‐resonant peaks glucose, betaine, and TMAO during fatty liver disease was detected (ADCs = 0.60 ± 0.11 and 0.35 ± 0.1 * 10−9 m2s−1 (n = 3) for rats fed with and without orotic acid), indicative of a reduction in glucose and betaine and an increase in TMAO. Magn Reson Med 50:925–930, 2003. © 2003 Wiley‐Liss, Inc.
Helical MR: Continuously moving table axial imaging with radial acquisitions
Authors: Shankaranarayanan Ajit , Herfkens Robert , Hargreaves Brian M. , Polzin Jason A. , Santos Juan M. , Brittain Jean H.
Published: October 2003

A technique for extended field of view MRI is presented. Similar to helical computed tomography, the method utilizes a continuously moving patient table, a 2D axial slice that remains fixed relative to the MRI magnet, and a radial k‐space trajectory. A fully refocused SSFP acquisition enables spatial resolution comparable to current clinical protocols in scan times that are sufficiently short to allow a reasonable breathhold duration. RF transmission and signal reception are performed using the RF body coil and the images are reconstructed in real time. Experimental results are presented that illustrate the technique's ability to resolve small structures in the table‐motion direction. Simulation experiments to study the steady‐state response of the fully refocused SSFP acquisition during continuous table motion are also presented. Finally, whole body images of healthy volunteers demonstrate the high image quality achieved using the helical MRI approach. Magn Reson Med 50:1053–1060, 2003. © 2003 Wiley‐Liss, Inc.
Variable‐density spiral 3D tailored RF pulses
Authors: Stenger V. Andrew , Boada Fernando E. , Noll Douglas C.
Published: October 2003

A variable‐density spiral method is presented for reducing three‐dimensional tailored radiofrequency pulse duration. Pulse length reductions of 21–32% are possible, with only a small error in the desired excitation profile. The method is demonstrated using simulations, phantom experiments, and T2*‐weighted images of brain regions with susceptibility‐induced intravoxel dephasing. Four 19.7‐ms shots were needed to excite a 5‐mm‐thick slice with reduced susceptibility artifacts in the sinus region at 3T. Magn Reson Med 50:1100–1106, 2003. © 2003 Wiley‐Liss, Inc.
Utilization of an intra‐oral diamagnetic passive shim in functional MRI of the inferior frontal cortex
Authors: Wilson James L. , Jezzard Peter
Published: October 2003

Due to the presence of gross magnetic susceptibility artifacts, functional MRI (fMRI) has proved problematic in studies of the human inferior frontal cortex (IFC). There is a strong desire, therefore, to employ techniques that mitigate susceptibility artifacts in the IFC while preserving the imaging parameters of an fMRI study. It has been shown that the use of a single, strongly diamagnetic, intra‐oral passive shim significantly improves the homogeneity of the static magnetic field (B0) and, as a result, alleviates the susceptibility artifacts within the IFC. In this study, practical issues regarding the use of an intra‐oral passive shim are examined. We investigated B0 instabilities within the IFC resulting from subject head motion in order to calculate the effects of an intra‐oral passive shim on the temporal variance of an EPI time series. These studies show that the addition of an intra‐oral passive shim improves both B0 homogeneity and signal stability, and increases sensitivity to functional activation. Magn Reson Med 50:1089–1094, 2003. © 2003 Wiley‐Liss, Inc.
Accuracy and reproducibility in phase contrast imaging using SENSE
Authors: Thunberg Per , Karlsson Matts , Wigström Lars
Published: October 2003

The purpose of this study was to evaluate the accuracy and reproducibility of phase contrast imaging using the sensitivity encoding (SENSE) method at different reduction factors. Analytical expressions were derived that state how reproducibility is influenced for velocity and flow measurements. Computer simulations, and in vitro and in vivo studies were performed in order to validate these expressions and to assess how accuracy is affected when different reduction factors are applied. It was shown that reproducibility depends on the reduction and geometry factors. Since the geometry factor varies spatially, so does the reproducibility for phase contrast imaging. In areas with high geometry factors, the standard deviation (SD) may become so large that aliasing occurs. The accuracy of phase contrast imaging is not influenced directly when SENSE is used, but may be indirectly influenced due to high SDs of the measured phase that may subsequently cause aliasing. The current results show that it is possible to achieve accurate flow measurements even at high reduction factors. By taking the geometry factor into account, it may be possible to find areas where phase contrast imaging is accurate even at high reduction factors. Magn Reson Med 50:1061–1068, 2003. © 2003 Wiley‐Liss, Inc.
Modulation of the pharmacokinetics of macromolecular contrast material by avidin chase: MRI, optical, and inductively coupled plasma mass spectrometry tracking of triply labeled albumin
Authors: Dafni Hagit , Gilead Assaf , Nevo Nava , Eilam Raya , Harmelin Alon , Neeman Michal
Published: October 2003

The goal of this work was to develop an MRI method for mapping the clearance of interstitial macromolecular plasma proteins after their extravasation from permeable blood vessels. To that end, a well‐defined window of exposure to elevated blood levels was generated by inducing rapid clearance of macromolecular contrast material from the blood. Experimental removal of the intravascular component allowed subsequent tracking of clearance from the interstitial compartment in the absence of further contrast extravasation. The contrast material was based on albumin triply labeled with biotin, fluorescent tag, and GdDTPA, allowing optical, inductively coupled plasma mass spectrometry (ICP‐MS) and MRI detection. The biotin tag was used here for in vivo chasing of the contrast material from the blood by intravenous administration of avidin. Upon administration of avidin the contrast material disappeared from the blood vessels and was cleared by the liver and spleen as detected by MRI, fluorescence of blood samples and histological sections, and by ICP‐MS. Nonbiotinylated fluorescent albumin was not affected by administration of avidin. Contrast material that extravasated from leaky blood vessels in a VEGF overexpressing tumor, prior to administration of avidin, was not cleared by the addition of avidin and showed continued interstitial convection. Thus, avidin‐chase provides an effective tool for in vivo manipulation of the arterial input function by providing experimental control over the rate of clearance of the contrast material from the circulation. Magn Reson Med 50:904–914, 2003. © 2003 Wiley‐Liss, Inc.
A Cbl:clathrin complex involved in NGF signaling for neurite outgrowth
Authors: Howe Charles L.
Published: October 2003

Cbl regulates receptor tyrosine kinase activity by promoting the endocytosis of receptors from the plasma membrane. The mechanism of this effect is unclear, but recent evidence suggests that Cbl mediates ubiquitin‐dependent sorting of receptors following recruitment to phosphotyrosine motifs in the activated receptor. Moreover, recent findings support a role for Cbl in the clathrin‐mediated endocytosis of receptor tyrosine kinases. We provide evidence that Cbl is found in complex with clathrin and is localized to clathrin‐coated vesicles following NGF stimulation of TrkA. We also show that overexpression of Cbl enhances clathrin‐mediated endocytosis of 125I‐NFG, and that this increased internalization is correlated with a substantial acceleration of neurite outgrowth in response to NGF. Our data suggest that Cbl may participate in the formation of a multi‐protein complex involved in the clathrin‐mediated endocytosis of receptor tyrosine kinases, and that Cbl may function as a positive regulator of such kinases in specific cellular contexts.
Time dependence of the effect of ethanol on serotonin synthesis and tryptophan hydroxylase expression in the dorsal and median raphe of young rats
Authors: Jang Mi‐Hyeon , Shin Min‐Chul , Kim Hong , Kim Ee‐Hwa , Kim Chang‐Ju
Published: October 2003

Serotonin (5‐hydroxytryptamine, 5‐HT) has been implicated in the pathophysiology of many neuropsychiatric disorders, and alcohol is reported to influence serotonergic neuronal activity in the dorsal raphe. In the present study, the effects of ethanol on the synthesis of 5‐HT and the expression of tryptophan hydroxylase (TPH), the rate‐limiting enzyme of 5‐HT synthesis, in the dorsal and median raphe of rats were investigated, using immunohistochemial methods. Results showed that the density of 5‐HT‐positive and TPH‐positive cells was reduced by ethanol treatment in a time‐dependent manner. Based on these results, it is suggested that the pathogenesis of ethanol‐induced neuropsychological disorders involves ethanol‐induced suppression of 5‐HT synthesis and TPH expression in the raphe region.