bluuebunny/crossref_metadata_2025_split huggingface dataset:
Randomized comparison of cognitive function in humans at 0 and 8 Tesla
Authors: Chakeres Donald W. , Bornstein Robert , Kangarlu Allahyar 
Published: August 2003

AbstractPurposeTo discover whether there was a measurable alteration in cognitive performance in humans when exposed to a static magnetic field of 8 Tesla (T).Materials and MethodsTwenty‐five normal human subjects were evaluated at both 0.05 and 8 T in a randomized order. Six standardized neuropsychological tests were administered and auditory reaction times were assessed. The cognitive assessment included measures of learning and retention, verbal fluency (spontaneous word generation), auditory attention, and auditory working memory. Alternate test forms were utilized to reduce practice effects. The sequential order of testing, 0.05 T first vs. 8 T first exposure, was randomized. The data was analyzed using univariate comparisons for correlated means to assess potential differences under the two conditions.ResultsThere were no clinically significant differences in any of the measures. On a measure of recognition memory the subjects performed significantly better in the 0.05T condition, but the difference was extremely small, not clinically meaningful, and likely due to statistical artifact.ConclusionThis study shows that exposure of the brain to high magnetic fields of up to 8 T does not appear to alter human cognitive performance. J. Magn. Reson. Imaging 2003;18:342–345. © 2003 Wiley‐Liss, Inc.
Effect of static magnetic field exposure of up to 8 Tesla on sequential human vital sign measurements
Authors: Chakeres Donald W. , Kangarlu Alayar , Boudoulas Harisios , Young Donn C. 
Published: August 2003

AbstractPurposeTo determine if increasing static magnetic field strength exposures up to 8 Tesla (T) affect vital signs or electrocardiograms (ECGs) in normal human volunteers.Materials and MethodsWe studied 25 normal subjects, consisting of 19 men and six women, ages 24–53 years. The vital signs and ECGs of the subjects were measured 14 times inside and outside the magnetic field. This included the heart rate, respiratory rate, systolic and diastolic blood pressures, finger pulse oxygenation levels, core body temperature via the external auditory canal temperature, and fiber optic core body sublingual temperatures. Inside the magnetic field the vital signs were measured sequentially at field strengths of 8, 6, 4.5, 3, and 1.5 T.ResultsThe only statistically significant effect of magnetic field strength was observed with systolic blood pressure. An average increase of 3.6 mm Hg in systolic blood pressure was seen with 8 T exposure. ECG rhythm strip analysis demonstrated no significant changes post‐exposure.ConclusionsNormal subjects exposed to varying magnetic field strengths of up to 8 T demonstrated no clinically significant changes in vital signs. Transient ECG artifacts were noted to increase with the field strength. J. Magn. Reson. Imaging 2003;18:346–352. © 2003 Wiley‐Liss, Inc.
Pain dynamics observed by functional magnetic resonance imaging: Differential regression analysis technique
Authors: Cho Zang‐Hee , Son Young‐Don , Kang Chang‐Ki , Han Jae‐Yong , Wong Edward K. , Bai Sun‐Joon 
Published: August 2003

AbstractPurposeTo observe the dynamic responses of the cortical areas related to the pain processing by using the differential regression analysis (DRA) technique in functional magnetic resonance imaging (fMRI) and investigation of pain mechanisms.Materials and MethodsFor pain studies, thermal stimulation was applied by immersing the index finger into a hot bath of water with a temperature of 50–52°C. Motor (finger tapping) and visual (flickering light) stimulation experiments were conducted to elucidate the physiological differences between the simple sensory tasks and pain tasks. To obtain dynamic responses, T values (regression analysis) were sequentially estimated by using a series of shifted differential window functions (narrow width).ResultsBy using the DRA technique, well‐defined prompt responses were observed for both motor and visual stimuli. On the other hand, in the pain experiment, a set of sequentially varying responses was observed for the thalamus (Thal), the dorsal anterior cingulate cortex (dACC), the caudal ACC (cACC), and the rostral ACC (rACC). This time‐dependent response suggests the dynamics of pain signal processing in cortical areas.ConclusionThe results support the hypothesis that the activated areas are similar to the previously reported pain processing areas; however, new sequential responses were observed, suggesting that the technique may reveal dynamics of pain perception and their pathway, important elements in understanding the mechanism of pain. The DRA technique can provide a new opportunity for many spatiotemporal analyses, for example, the physiologically complex and little‐studied physiological phenomena, such as pain dynamics. J. Magn. Reson. Imaging 2003;18:273–283. © 2003 Wiley‐Liss, Inc.
Method for quantitation of dynamic MRI contrast agent uptake in colorectal liver metastases
Authors: van Laarhoven Hanneke W.M. , Rijpkema Mark , Punt Cornelis J.A. , Ruers Theo J. , Hendriks Jan C.M. , Barentsz Jelle O. , Heerschap Arend 
Published: August 2003

AbstractPurposeTo investigate the reproducibility of dynamic contrast‐enhanced MRI (DCE‐MRI) in colorectal liver metastases using a vascular normalization function (VNF) from pixels in the spleen and to compare this with a technique using an arterial input function (AIF) from pixels in the aorta.Materials and MethodsDCE‐MRI with gadolinium‐DTPA (Gd‐DTPA) was performed in patients with colorectal liver metastases. The VNF and AIF were determined using an automated algorithm. The average Gd‐DTPA uptake rate (kep) was calculated for the metastases using a physiological pharmacokinetic model. The protocol was repeated on a second day to calculate the repeatability coefficient of the measurements of kep.ResultsUsing the VNF from the spleen the overall mean kep of the two sessions for 11 patients was 0.033 per second and the repeatability coefficient was 0.009 per second. Using the AIF from the aorta these values were 0.031 per second and 0.028 per second, respectively.ConclusionThe mean Gd‐DTPA uptake rate using a VNF taken from the spleen can be determined with adequate reproducibility in colorectal liver metastases. The use of a VNF from pixels in the spleen is better than an AIF from pixels in the aorta in terms of reproducibility, and is recommended when this DCE‐MRI technique is used for prediction and monitoring of therapy outcome in colorectal liver metastases. J. Magn. Reson. Imaging 2003;18:315–320. © 2003 Wiley‐Liss, Inc.
Magnetization transfer contrast imaging in Niemann pick type C mouse liver
Authors: Guo Jingyu , Erickson Robert , Trouard Theodore , Galons Jean‐Philippe , Gillies Robert 
Published: August 2003

AbstractPurposeTo investigate livers of mice afflicted with Niemann Pick type C (NP‐C) disease using magnetization transfer contrast (MTC) imaging and to test the hypothesis that the MT ratio reproducibly changes during disease progression.BackgroundNP‐C is a heritable defect of lipid metabolism that results in the accumulation of unesterified cholesterol and gangliosides in virtually all cells. Symptoms predominate in brain and liver, which have high endogenous rates of lipid turnover. It is fatal to children, usually early in the second decade of life. Previous work has shown that the efficiency of magnetization transfer (MT) can be affected by cholesterol and collagen in tissues. The MT ratio (MTR) was calculated and compared during growth and therapy of diseased and control mice.ResultsSignificant differences in the MTR were observed between livers of diseased and control mice. These ratios were consistent with collagen deposition associated with fibrosis, and not the accumulation of unesterified cholesterol in this organ.ConclusionThese results indicate that MTC imaging may have clinical potential for monitoring progression and therapy in NP‐C disease. J. Magn. Reson. Imaging 2003;18:321–327. © 2003 Wiley‐Liss, Inc.
Probing of arginine residues in peptides and proteins using selective tagging and electrospray ionization mass spectrometry
Authors: Leitner Alexander , Lindner Wolfgang 
Published: August 2003

AbstractA general labelling method is presented which allows the determination of the number of guanidine groups (related to arginine and homoarginine in peptides and proteins) by means of mass spectrometry. It implies a guanidine‐selective derivatization step with 2,3‐butanedione and an arylboronic acid under aqueous, alkaline conditions (pH 8–10). The reaction mixture is then directly analysed by electrospray ionization mass spectrometry without further sample pretreatment. Other amino acids are not affected by this reaction although it is demonstrated that lysine side‐chains may be unambiguously identified when they are converted to homoarginine prior to derivatization. Guanidine functionalities, as e.g. in the amino acid arginine, are easily identified by the characteristic mass shift between underivatized and derivatized analyte. The tagging procedure is straightforward and selective for guanidine groups. The influence of several experimental parameters, especially the pH of the solution and the choice of reagents, is examined and the method is applied to various arginine‐containing peptides and to lysozyme as a representative protein. Possible applications of this technique and its limitations are discussed. Copyright © 2003 John Wiley & Sons, Ltd.
Sensitive liquid chromatographic/tandem mass spectrometric method for the determination of beclomethasone dipropionate and its metabolites in equine plasma and urine
Authors: Guan Fuyu , Uboh Cornelius , Soma Lawrence , Hess Anne , Luo Yi , Tsang Deborah S. 
Published: August 2003

AbstractBeclomethasone dipropionate (BDP) is a potent pro‐drug to beclomethasone (BOH) and is used in the treatment of chronic and acute respiratory disorders in the horse. The therapeutic dose of BDP (325 µg per horse) by inhalation results in very low plasma and urinary concentrations of BDP and its metabolites that pose a challenge to detection and confirmation by equine forensic laboratories. To solve this problem, a method involving the use of a liquid chromatography coupled with tandem mass spectrometry (LC/MS/MS) was developed for the detection, confirmation and quantification of the analytes in equine samples. Ammonium formate or acetate buffer added to LC mobile phase favored the formation of [M + H]+ions from BDP and its metabolites, whereas formic acid led to the formation of sodium and potassium adduct ions ([M + Na]+, [M + K]+) together with [M + H]+ions. Acetonitrile, on the other hand, favored the formation of abundant solvent adduct ions [M + H + CH3CN]+with the analytes under electrospray ionization (ESI) and atmospheric pressure chemical ionization conditions. In contrast, methanol formed much less solvent adduct ions than acetonitrile. The solvent adduct ions were thermally stable and could not be completely desolvated under the experimental conditions, but they were very fragile to collision‐induced dissociation (CID). Interestingly, these solvent adduct ions were observed on a triple‐quadrupole mass spectrometry but not on an ion trap instrument where helium used as a damping gas in the ion trap might cause the solvent adduct ions desolvated by collision. By CID studies on the [M + H]+ions of BDP and its metabolites, their fragmentation paths were proposed. In equine plasma at ambient temperature over 2 h, BDP and B21P were hydrolyzed in part to B17P and BOH, respectively, but B17P was not hydrolyzed. Sodium fluoride added to equine plasma inhibited the hydrolysis of BDP and B21P. The matrix effect in ESI was evaluated in equine plasma and urine samples. The method involved the extraction of BDP and its metabolites from equine plasma and urine samples by methyltert‐butyl ether, resolution on a C8column with a mobile phase gradient consisting of methanol and ammonium formate (2 mmol l−1, pH 3.4) and multiple reaction monitoring for the analytes on a triple‐quadrupole mass spectrometer. The detection limit was 13 pg ml−1for BDP and B17P, 25 pg ml−1for BOH and 50 pg ml−1for B21P in plasma and 25 pg ml−1for BOH in urine. The method was successfully applied to the analysis of equine plasma and urine samples for the analytes following administration of BDP to horses by inhalation. B17P, the major and active metabolite of BDP, was detected and quantified in equine plasma up to 4 h post‐administration by inhalation of a very low therapeutic dose (325 µg per horse) of BDP. Copyright © 2003 John Wiley & Sons, Ltd.
Study of the fragmentation mechanism of novel functionalized macrocycles by Fourier transform ion cyclotron resonance mass spectrometry
Authors: Chen Hui , Du Da‐Ming , Hua Wen‐Ting , He Meiyu , Xin Bin 
Published: August 2003

AbstractLiquid secondary ion mass spectrometry (L‐SIMS) of six new functionalized macrocycles was investigated. All six compounds yielded abundant fragment ions and protonation molecular ions [M + H]+ under L‐SIMS conditions. The proposed fragmentation mechanisms were supported by high‐resolution accurate mass data from Fourier transform ion cyclotron resonance mass spectrometric and MSn experiments on using sustained off‐resonance irradiation collision‐induced dissociation. Copyright © 2003 John Wiley & Sons, Ltd.
Comparison of electrospray ionization and atmospheric pressure chemical ionization techniques in the analysis of the main constituents from Rhodiola rosea extracts by liquid chromatography/mass spectrometry
Authors: Tolonen Ari , Hohtola Anja , Jalonen Jorma 
Published: August 2003

AbstractRhodiola rosea L. (Golden Root) has been used for a long time as an adaptogen in Chinese traditional medicine and is reported to have many pharmacological properties. A liquid chromatographic (LC) method with mass spectrometric (MS) detection based on selected ion monitoring (SIM) was developed for determining salidroside, sachaliside 1, rosin, 4‐methoxycinnamyl‐O‐β‐glucopyranoside, rosarin, rosavin, cinnamyl‐(6′‐O‐β‐xylopyranosyl)‐O‐β‐glucopyranoside, 4‐methoxy‐cinnamyl‐(6′‐O‐α‐arabinopyranosyl)‐O‐β‐glucopyranoside, rosiridin and benzyl‐O‐β‐glucopyranoside from the callus and plant extracts in one chromatographic run. Good linearity over the range 0.5–500 ng ml−1 for salidroside, 2–2000 ng ml−1 for rosavin and 2–500 ng ml−1 for benzyl‐O‐β‐glucopyranoside was observed. The intra‐assay accuracy and precision within quantitation ranges varied between −10.0 and +13.2% and between 0.7 and 9.0%, respectively. Optimization of the ionization process was performed with electrospray and atmospheric pressure chemical ionization techniques using four different additive compositions for eluents in the LC/MS scan mode, using both positive and negative ion modes. The best ionization sensitivity for the compounds studied was obtained with electrospray ionization when using pure water without any additives as the aqueous phase. Copyright © 2003 John Wiley & Sons, Ltd.
Gas‐phase hydrogen/deuterium exchange of adenine nucleotides
Authors: Crestoni Maria Elisa , Fornarini Simonetta 
Published: August 2003

AbstractGas‐phase hydrogen/deuterium exchange reactions of (de)protonated (sodiated) adenosine‐5′‐mono‐, di‐ and triphosphate ions with CD3OD, CD3CO2D and ND3 were achieved using a combination of electrospray ionization and Fourier transform ion cyclotron resonance mass spectrometry. The reaction kinetics are dependent on factors such as the charge state, the phosphate chain length, the properties of the exchange reactants and the sodium content. The results indicate that the overall H/D exchange may involve specific sites even if endowed with high energetic barriers. The enhanced reactivity exhibited by adenosine polyphosphate ions compared with adenosine‐5′‐monophosphate suggests a critical role of the polyphosphate chain in rendering conformationally accessible remote H‐donor sites. Low‐energy collision‐induced dissociation of (sodiated) adenine nucleotides anions supports the aptitude of the (poly)phosphate chain in probing distant sites via the intermediacy of a cyclic structure. Copyright © 2003 John Wiley & Sons, Ltd.
Band composition analysis: a new procedure for deconvolution of the mass spectra of organometallic compounds
Authors: Szymura Jacek A. , Lamkiewicz Jan 
Published: August 2003

AbstractA new chemometric procedure called band composition analysis (BCA) designed for the deconvolution of mass spectra of organometallics is proposed. BCA generates theoretical bands Ti, then combines them to obtain a model band M, which is finally compared with the experimental band E. All of these steps are realized with computer assistance. This modeling yields four parameters characterizing the experimental band: theoretical and model variances s2theor and s2model, a fit factor α and a contribution xi from the theoretical band. If s2theor > 20 the band is deemed complex and needs modeling. The values α > 90 indicate that there is good agreement between the experimental and model bands. BCA is particularly effective for the modeling of complex isotopic bands often present in organometallics. Two illustrations of BCA for tetrabutyltin, C16H36Sn, and 1,1′,2,2′,3,3′‐hexachloroferrocene, C10H4Cl6Fe, are shown. Copyright © 2003 John Wiley & Sons, Ltd.
Stable isotope labeling for matrix‐assisted laser desorption/ionization mass spectrometry and post‐source decay analysis of ribonucleic acids
Authors: Berhane Beniam T. , Limbach Patrick A. 
Published: August 2003

AbstractMatrix‐assisted laser desorption/ionization mass spectrometry is a powerful analytical tool for the structural characterization of oligonucleotides and nucleic acids. Here we report the application of stable isotope labeling for the simplified characterization of ribonucleic acids (RNAs). An 18O label is incorporated at the 3′‐phosphate of oligoribonucleotides during the enzymatic processing of intact RNAs. As implemented, a buffer solution containing a 50 : 50 mixture of H2O and 18O‐labeled H2O is used during endonuclease digestion. Upon digestion, characteristic doublets representative of the isotopic distribution of oxygen are noted for those products that contain 3′‐phosphate groups. This approach is used to distinguish readily endonuclease digestion products from incomplete digestion products and non‐specific cleavage products. In addition, RNase digestion products containing the characteristic isotopic doublet can be selected for further characterization by post‐source decay (PSD) analysis. PSD products carrying the 3′‐phosphate group will appear as a doublet, thereby simplifying fragment ion assignment. Copyright © 2003 John Wiley & Sons, Ltd.
Strategy for structural elucidation of drugs and drug metabolites using (MS)n fragmentation in an electrospray ion trap
Authors: Tozuka Zenzaburo , Kaneko Hayato , Shiraga Toshifumi , Mitani Yasuyuki , Beppu Manabu , Terashita Shigeyuki , Kawamura Akio , Kagayama Akira 
Published: August 2003

AbstractTriple‐stage quadrupole (TSQ) electrospray ionization (ESI) tandem mass spectrometry (MS/MS) and ion trap ESI‐MS/MS can be used to cleave protonated molecules to produce carbocations and neutral molecules in the positive ion mode. Dissociation products which correspond to protonated forms of neutral fragment molecules can also be trapped and detected. These protonated molecules in turn can cleave via carbocation cleavage, ipso cleavage, onium cleavage or McLafferty or related rearrangements. One can elucidate the structures of metabolites from the differences in m/z ratios of the fragments arising from the original drug compound and its metabolite. This strategy for structural elucidation is further facilitated by estimates of the reactivity of drugs with oxygen diradicals involved in cytochrome P‐450 cycles. Copyright © 2003 John Wiley & Sons, Ltd.
Deletions in env gene of HIV‐1 in AIDS patients treated with highly active antiretroviral therapy (HAART)
Authors: Saurya Shreesh , Lichtenstein Zelman , Karpas Abraham 
Published: August 2003

AbstractMany AIDS patients retain high CD4+ T‐cell counts despite a significant increase in PCR viral load after varied periods of treatment on drug combination with Highly Active Antiretroviral Therapy (HAART). In order to investigate this contradictory phenomenon, we assayed for infectious HIV‐1 from the plasma of such patients. Since the biological assays failed to reveal any infectious virus, we undertook molecular characterization of the plasma HIV‐1 genes. These studies revealed large deletions in the env gene of the free virus, while there were no deletions in the proviral DNA obtained from the infected cells of the patients' blood. This suggests that the viral particles produced and released by the infected cells during the HAART treatment have deletions in the env gene. The deletions were large enough to produce an envelop‐deficient virus, which can readily explain why it is not infectious. Such a defective virus is the most likely explanation for its failure to infect the T‐cells, which in turn lead to the discordance between the high PCR viral load and stable CD4+ T cell counts. J. Med. Virol. 71:167–172, 2003. © 2003 Wiley‐Liss, Inc.
HIV‐2 derived lentiviral vectors: Gene transfer in Parkinson's and Fabry disease models in vitro
Authors: D'Costa Jenice , Harvey‐White Judith , Qasba Pankaj , Limaye Advait , Kaneski Christine R. , Davis‐Warren Alberta , Brady Roscoe O. , Bankiewicz Krys S. , Major Eugene O. , Arya Suresh K. 
Published: August 2003

AbstractLentiviral vectors are prime candidate vectors for gene transfer into dividing and non‐dividing cells, including neuronal cells and stem cells. For safety, HIV‐2 lentiviral vectors may be better suited for gene transfer in humans than HIV‐1 lentiviral vectors. HIV‐2 vectors cross‐packaged in HIV‐1 cores may be even safer. Demonstration of the efficacy of these vectors in disease models will validate their usefulness. Parkinson's disease and Fabry disease provide excellent models for validation. Parkinson's disease is a focal degeneration of dopaminergic neurons in the brain with progressive loss of ability to produce the neurotransmitter dopamine. Current treatment entails administration of increasing doses of L‐dopa, with attendant toxicity. We explore here the hypothesis that gene transfer of aromatic acid decarboxylase (AADC), a key enzyme in the pathway, will make neuronal cells more efficiently convert L‐dopa into dopamine. Fabry disease on the other hand is a monogenic inherited disease, characterized by α‐galactosidase A (AGA) deficiency, resulting in glycolipid accumulation in several cell types, including fibroblasts. Animal models for preclinical investigations of both of these diseases are available. We have designed monocistronic HIV‐1 and HIV‐2 vectors with the AADC transgene and monocistronic and bicistronic HIV‐2 vectors with the AGA and puromycin resistance transgenes. They were packaged with either HIV‐2 cores or HIV‐1 cores (hybrid vectors). Gene transfer of AADC gene in neuronal cells imparted the ability on the transduced cells to efficiently convert L‐dopa into dopamine. Similarly, the AGA vectors induced Fabry fibroblasts to produce high levels of AGA enzyme and caused rapid clearance of the glycolipids from the cells. Both monocistronic and bicistronic vectors were effective. Thus, the insertion of a second gene downstream in the bicistronic vector was not deleterious. In addition, both the self‐packaged vectors and the cross‐packaged hybrid vectors were effective in gene transfer. J. Med. Virol. 71:173–182, 2003. © 2003 Wiley‐Liss, Inc.