bluuebunny/crossref_metadata_2025_split huggingface dataset:
A new insight into suction and dilution effects in capillary electrophoresis coupled to mass spectrometry via an electrospray ionization interface. Part I‐Suction effect
Authors: Mokaddem Meriem , Gareil Pierre , Belgaied Jamel‐Eddine , Varenne Anne 
Published: April 2008

AbstractThe hyphenation of CE with MS is nowadays accepted as a powerful analytical approach. Employing ESI, the most common interface, one challenge is to provide quantitative information, which is quite a difficult task, as it is linked, among other factors, to suction and dilution effects. In the coaxial ESI configuration, the suction effect has been presented in literature as stemming from nebulizing gas (NG) flow rate and drying gas temperature. But as this interface consists in three concentric capillaries, allowing for BGE, sheath liquid (SL) and NG mixing, it is demonstrated herein that other parameters are also involved in this suction effect: the CE capillary protrusion from the interface needle, SL flow rate, and overall BGE flow rate and velocity profile. Whereas NG flow rate is the parameter affecting suction to a greater extent, separation capillary protruding length, SL, and overall BGE flow rate have a significant additional impact on this phenomenon. It is shown that SL flow rate can affect suction differently according to the NG velocity, which may be explained by modification of the Taylor cone geometry. Furthermore, it appears that suction effect is noticeably favored by a parabolic velocity profile of the BGE, again probably due to the Taylor cone shape modification. Finally, the temperature gradient created by the contact between the heated NG and the separation capillary enhances this effect.
“Mind the gap”: Caves, radiocarbon sequences, and the Mesolithic–Neolithic transition in Europe—lessons from the Mala Triglavca rockshelter site
Authors: Mlekuž Dimitrij , Budja Mihael , Payton Robert , Bonsall Clive 
Published: April 2008

AbstractRadiocarbon sequences from some northern Mediterranean cave sites show a temporal gap between Mesolithic and Neolithic occupations. Some authors regard this as a regional phenomenon and have sought to explain it in terms of a general population decline in the late Mesolithic, which facilitated the replacement of indigenous foragers by immigrant farmers. New evidence from the rockshelter site of Mala Triglavca, in Slovenia, leads us to question this view. We describe the deposits in the rockshelter and discuss the results of AMS radiocarbon dating of bone samples recovered in excavations in the 1980s. New archaeological investigations and associated soil/sediment analyses show that in the central part of the rockshelter a well‐defined stratigraphic sequence can be established, despite post‐depositional modification by soil forming processes. There is also evidence of substantial post‐depositional disturbance of the cave sediments by human agency and geomorphological processes, which have created “temporal gaps” and “inversions” in the radiocarbon sequence. The relatively large series of radiocarbon dates obtained enables some of the post‐depositional processes to be identified. © 2008 Wiley Periodicals, Inc.
The location of specialized copper production by the lost wax technique in the Chalcolithic southern Levant
Authors: Goren Yuval 
Published: April 2008

AbstractThe origins of southern Levantine Chalcolithic copper metallurgy have been debated for decades. Typological and metallurgical examinations of the copper artifacts from the Nahal Mishmar hoard and elsewhere have indicated a dichotomy between simple tools, made of pure copper by open casting, and elaborate items made by the “lost wax” technique of copper alloys with arsenic, antimony, and nickel. While the first were considered local production of the northern Negev sites, the prestige objects were either considered as imports from the remote sources of arsenic copper, or local to the southern Levant. The present paper presents the results of a research project that was aimed at examining this issue through the analysis of ceramic mold remains that were still attached to a large number of copper implements from Israel. The En Gedi area in the Judean Desert of Israel is identified as the place of origin of all copper objects produced by this method. Based on the results, some new interpretations are suggested to the complex topic of Chalcolithic copper metallurgy. © 2008 Wiley Periodicals, Inc.
On multiple‐testing correction in genome‐wide association studies
Authors: Moskvina Valentina , Schmidt Karl Michael 
Published: April 2008

AbstractThe interpretation of the results of large association studies encompassing much or all of the human genome faces the fundamental statistical problem that a correspondingly large number of single nucleotide polymorphisms markers will be spuriously flagged as significant. A common method of dealing with these false positives is to raise the significance level for the individual tests for association of each marker. Any such adjustment for multiple testing is ultimately based on a more or less precise estimate for the actual overall type I error probability. We estimate this probability for association tests for correlated markers and show that it depends in a nonlinear way on the significance level for the individual tests. This dependence of the effective number of tests is not taken into account by existing multiple‐testing corrections, leading to widely overestimated results. We demonstrate a simple correction for multiple testing, which can easily be calculated from the pairwise correlation and gives far more realistic estimates for the effective number of tests than previous formulae. The calculation is considerably faster than with other methods and hence applicable on a genome‐wide scale. The efficacy of our method is shown on a constructed example with highly correlated markers as well as on real data sets, including a full genome scan where a conservative estimate only 8% above the permutation estimate is obtained in about 1% of computation time. As the calculation is based on pairwise correlations between markers, it can be performed at the stage of study design using public databases. Genet. Epidemiol. 2008. 2008 Wiley‐Liss, Inc.
Selection of high-avidity CD8 T cells correlates with control of hepatitis C virus infection
Authors: Neveu Bérangère , Debeaupuis Emilie , Echasserieau Klara , le Moullac-Vaidye Béatrice , Gassin Michelle , Jegou Loïg , Decalf Jérémie , Albert Matthew , Ferry Nicolas , Gournay Jérôme , Houssaint Elisabeth , Bonneville Marc , Saulquin Xavier 
Published: April 2008

Abstract

Both strong antigenic avidity and acquisition of proper effector functions contribute to the efficacy of antiviral T cell responses. To correlate these parameters with the outcome of hepatitis C virus (HCV) infection, we characterized HCV-specific CD8 T cell lines isolated after immunomagnetic sorting of peripheral blood mononuclear cells from human leukocyte antigen A*02 (HLA-A*02) individuals with various HCV serological statuses, using recombinant HLA-A*0201 multimers loaded with three immunodominant HCV genotype 1-derived epitopes. CD8 T cells specific for these three epitopes were derived from most HLA-A*0201 individuals, regardless of their HCV serology or clinical outcome. Donors recovered from genotype 1 HCV infection were enriched for high-avidity T cells with enhanced interferon gamma (IFN-γ), tumor necrosis factor alpha, and cytotoxic T lymphocyte responses, when compared with seronegative donors and seropositive patients infected with irrelevant HCV genotypes. Patients chronically infected with genotype 1 strain yielded almost exclusively low-avidity T cells, whose hyporesponsiveness was primarily attributable to low T cell receptor (TCR) avidity rather than intrinsic functional defects.

Conclusion:

This study suggests that strong IFN-γ responses associated with efficient viral clearance primarily result from Ag-driven selection/survival of HCV-specific T cells expressing high-avidity TCR. It also suggests a link between the quality of the initial HCV-specific T cell repertoire and susceptibility to chronic infection. (Hepatology 2008.)
Single-nucleotide polymorphism analysis of the multidrug resistance protein 3 gene for the detection of clinical progression in Japanese patients with primary biliary cirrhosis
Authors: Ohishi Yuki , Nakamura Minoru , Iio Naomi , Higa Shingo , Inayoshi Mao , Aiba Yoshihiro , Komori Atsumasa , Omagari Katsuhisa , Ishibashi Hiromi , Tsukamoto Kazuhiro 
Published: April 2008

Abstract

Primary biliary cirrhosis (PBC) is a multifactorial disease in which genetic factors rather than environmental factors may predominantly contribute to the pathogenesis. In order to identify the genetic determinants of the disease severity and progression of PBC, we examined an association of seven tag single-nucleotide polymorphisms (SNPs) in the multidrug resistance protein 3 (

MDR3/ABCB4

) gene in 148 Japanese PBC patients and 150 age- and sex-matched healthy control subjects. SNPs were detected via polymerase chain reaction (PCR) restriction fragment length polymorphism and PCR direct DNA sequencing methods. Subsequently, haplotypes were constructed from three tag SNPs (rs31658, rs31672, and rs1149222) that were significantly associated with progression of PBC. Logistic regression analyses revealed that a Hap 2 haplotype and its homozygous diplotype, Hap 2/Hap 2, in

MDR3

were closely associated with the susceptibility to jaundice-type progression of PBC [

P

= 0.004, odds ratio (OR) 3.93, 95% confidence interval (CI) 1.56–9.90 and

P

= 0.0003, OR 17.73, 95% CI 3.77–83.42, respectively]. Conversely, another haplotype, Hap 1, and its homozygous diplotype, Hap 1/Hap 1, were associated with the insusceptibility to the progression to late-stage PBC (

P

= 0.021, OR 0.55, 95% CI 0.33–0.91 and

P

= 0.011, OR 0.24, 95% CI 0.08–0.71, respectively).

Conclusion:

The present study is the first report of an association of

MDR3

haplotypes and diplotypes with progression of PBC. The Hap 2/Hap 2 diplotype in

MDR3

could therefore be potentially applied to DNA-based diagnosis in Japanese patients with PBC as a strong genetic biomarker for predicting the progression and prognosis of PBC. (Hepatology 2008.)
Cathepsin L inhibitor I blocks mitotic chromosomes decondensation during cleavage cell cycles of sea urchin embryos
Authors: Morin Violeta , Sanchez Andrea , Quiñones Karin , Huidobro Jenaro Garcia , Iribarren Claudio , Bustos Paula , Puchi Marcia , Genevière Anne Marie , Imschenetzky Maria 
Published: April 2008

AbstractWe have previously reported that sperm histones (SpH) degradation after fertilization is catalyzed by a cystein–protease (SpH‐protease). Its inhibition blocks the degradation of SpH in vivo and also aborts sea urchin development at the initial embryonic cell cycles. It remains unknown if this effect is a consequence of the persistence of SpH on zygotic chromatin, or if this protease is involved per‐se in the progression of the embryonic cell cycles. To discriminate among these two options we have inhibited this protease at a time when male chromatin remodeling was completed and the embryos were engaged in the second cell cycle of the cleavage divisions. The role of this enzyme in cell cycle was initially analyzed by immuno‐inhibiting its SpH degrading activity in one of the two blastomeres after the initial cleavage division, while the other blastomere was used as a control. We found that in the blastomere injected with the anti‐SpH‐protease antibodies the cytokinesis was arrested, the chromatin failed to decondense after mitosis and BrdU incorporation into DNA was blocked. Since the N‐terminal sequence and the SpH protease was homologous to the cathepsin L (Cat L) family of proteases, we subsequently investigated if the deleterious effect of the inhibition of this protease is related to its Cat L activity. In this context we analyzed the effect of Cat L inhibitor I (Z–Phe‐Phe–CH2F) on embryonic development. We found that the addition of 100 uM of this inhibitor to the embryos harvested at the time of the initial cleavage division (80 min p.i.) mimics perfectly the effects of the immuno‐inhibition of this enzyme obtained by microinjecting the anti‐SpH–protease antibodies. Taken together these results indicate that the activity of this protease is required for embryonic cell cycle progression. Interestingly, we observed that when this protease was inhibited the chromatin decondensation after mitosis was abolished indicating that the inhibition of this enzyme affects chromosomes decondensation after mitosis. J. Cell. Physiol. 216: 790–795, 2008, © 2008 Wiley‐Liss, Inc.
Single‐breathhold four‐dimensional assessment of left ventricular volumes and function using k‐t BLAST after application of extracellular contrast agent at 3 Tesla
Authors: Hamdan Ashraf , Kelle Sebastian , Schnackenburg Bernhard , Wellnhofer Ernst , Fleck Eckart , Nagel Eike 
Published: April 2008

AbstractPurposeTo prospectively determine the feasibility and accuracy of a four‐dimensional (4D) k‐space over time broad‐use linear acquisition speed‐up technique (k‐t BLAST) for the evaluation of left ventricular (LV) volumes in comparison to standard multiple‐breathhold cine imaging, using a 3.0 Tesla (3T) MR system.Materials and MethodsIn 23 subjects, short‐axis cine loops completely covering the LV were acquired using conventional turbo gradient echo (GRE) imaging. Immediately after administration of gadobenate dimeglumine, a rapid single‐breathhold k‐t BLAST 4D dataset with the same coverage was acquired and reconstructed to short‐axis views. Quantitative aortic flow measurement for LV stroke volume (LVSV) was used to calibrate both techniques. For GRE and k‐t BLAST cine imaging: LV volumes, ejection fraction (EF), and blood‐to‐myocardium‐contrast (BMC) were determined.Resultsk‐t BLAST and GRE sequences showed a strong correlation for LV volumes and EF (r = 0.97–0.99; P < 0.001). Excellent agreement was also found between the LVSV determined by aortic flow measurements and LVSV assessed using GRE sequence and k‐t BLAST sequence. BMC of GRE was similar to that of k‐t BLAST cine imaging.ConclusionThe use of the single‐breathhold 4D k‐t BLAST technique for the assessment of LV volume is feasible and accurate in 3T MRI. J. Magn. Reson. Imaging 2008;27:1028–1036. © 2008 Wiley‐Liss, Inc.
Assessment of muscle oxygenation with balanced SSFP: A quantitative signal analysis
Authors: Klarhöfer Markus , Madörin Philipp , Bilecen Deniz , Scheffler Klaus 
Published: April 2008

AbstractPurposeTo investigate the feasibility of balanced steady‐state free precession (b‐SSFP) for blood oxygenation level–dependent (BOLD) MRI during a short‐term ischemia/reactive hyperemia (RH) experiment on human calf muscles.Materials and MethodsTo investigate contributions to the b‐SSFP signal during an RH experiment, the relaxation times T1, T2, and T were quantified in an interleaved fashion. Data from soleus, gastrocnemius, and tibialis muscle groups of five healthy subjects were evaluated.ResultsDuring ischemia a decreased b‐SSFP signal amplitude as well as a decrease in T2, T, and the initial intensity I0 was observed. RH provoked an overshoot of T2, T, and the b‐SSFP signal. No paradigm‐related changes in T1 were observed. Comparing the evolution of transverse relaxation times, initial intensity, and b‐SSFP signal amplitude, we concluded that the measured b‐SSFP signal in muscle tissue is not only determined by T2 variations but also significantly influenced by I0 changes. These I0 changes are attributed to spin density variations since inflow effects were suppressed by saturation bands.Conclusionb‐SSFP signal changes during a RH paradigm cannot unambiguously be assigned to oxygenation changes. Therefore, care has to be taken with their interpretation. J. Magn. Reson. Imaging 2008;27:1169–1174. © 2008 Wiley‐Liss, Inc.
Determining exercise‐induced blood flow reserve in lower extremities using phase contrast MRI
Authors: Nagaraj Hosakote M. , Pednekar Amol , Corros Cecilia , Gupta Himanshu , Lloyd Steven G. 
Published: April 2008

AbstractPurposeTo study the changes in limb blood flow during lower extremity exercise using phase contrast (PC) MRI in normal volunteers.Materials and MethodsHealthy volunteers performed plantar flexion exercise (<1 W) for four minutes. Flow velocity was measured using cardiac‐gated, cine PC‐MRI sequences (fast gradient recalled echo [GRE]; multishot echo planar imaging [EPI]) on a 3T scanner at the level of the superficial femoral artery (SFA): 1) preexercise; 2) immediately postexercise; 3) during three minutes recovery; and 4) postrecovery.ResultsAt rest there was a triphasic flow waveform in the SFA. During exercise it changed to a monophasic pattern with an increase in total flow; there were variable changes in vessel size and flow velocity. The waveform regained the triphasic pattern during recovery. The exercise‐induced flow reserve (FR) was 167 ± 90%.ConclusionPC‐MRI demonstrates that the resting triphasic flow waveform transforms into a monophasic pattern with submaximal exercise and returns to baseline with recovery. This increase in the regional blood flow allows for measurement of exercise‐induced FR in the SFA. J. Magn. Reson. Imaging 2008;27:1096–1102. © 2008 Wiley‐Liss, Inc.
Comparison of quantitative coronary angiography and first‐pass perfusion magnetic resonance imaging for the detection of an impaired coronary perfusion in nonsevere coronary stenosis
Authors: Barmeyer Achim A. , Stork Alexander , Muellerleile Kai , Schofer Anne K. , Tiburtius Claudia , Koester Ralf , Heitzer Thomas , Adam Gerhard , Meinertz Thomas , Lund Gunnar K. 
Published: April 2008

AbstractPurposeTo compare quantitative coronary angiography (QCA) and first‐pass perfusion magnetic resonance imaging (FPP‐MRI) in symptomatic patients with nonsevere coronary stenosis to detect a reduced coronary flow velocity reserve (CFVR).Materials and MethodsIn 35 patients, FPP‐MRI and CFVR measurements were performed in 40 coronary arteries with a diameter stenosis (DS) <70% by QCA. From FPP‐MRI a myocardial perfusion reserve index (MPRI) was calculated. CFVR was calculated as the ratio of the average peak flow velocity during infusion of adenosine and at rest and was considered reduced if <2. Diagnostic performance of MPRI and DS to detect a reduced CFVR was compared by receiver operating characteristic (ROC) curve analysis.ResultsCFVR was reduced in 16 coronary arteries (40%). Mean DS did not differ in coronary arteries with a reduced CFVR (41.0% ± 13.3) and a normal CFVR (36.5% ± 12.3; P = 0.281). Mean MPRI was lower in coronary arteries with a reduced CFVR (1.12 ± 0.12) compared to a normal CFVR (1.33 ± 0.2; P < 0.001). Sensitivity, specificity, and area under the ROC curve (AUC) were higher for MPRI (81%, 79%, 0.84) than for DS (56%, 58%, 0.60).ConclusionFPP‐MRI detects impaired CFVR in symptomatic patients with nonsevere coronary stenosis more accurately than QCA and can identify patients with symptomatic ischemia. J. Magn. Reson. Imaging 2008;27:1005–1011. © 2008 Wiley‐Liss, Inc.
Interstudy reproducibility of SSFP cine magnetic resonance: Impact of magnetic field strength and parallel imaging
Authors: Maroules Christopher D. , McColl Roderick , Khera Amit , Peshock Ronald M. 
Published: April 2008

AbstractPurposeTo study the effects of field strength and parallel imaging on image contrast and interstudy reproducibility of right and left ventricular (RV and LV) measurements using steady‐state free precession (SSFP) cardiovascular magnetic resonance (CMR).Materials and MethodsThirty‐two subjects (20 normal, 12 cardiac patients) underwent four SSFP cine short‐axis imaging studies: two at 1.5T, one at 3T, and another at 3T with parallel imaging (SENSE). RV and LV contrast‐to‐noise ratios (CNRs) were compared between methods. Interstudy reproducibility of RV and LV measurements were assessed by Bland–Altman analyses.Results3T SENSE imaging reduced total imaging time from 8 ± 2 minutes to 3 ± 1 minute (P < 0.001). A significant gain in LV CNR was detected between 1.5T and 3T with SENSE (43.8 ± 6.5 vs. 48.4 ± 7.4, P = 0.01), but no significant gain was detected in RV CNR. The reproducibility of LV and RV measurements between two 1.5T studies was not significantly different from the reproducibility between a 1.5T study and a 3T study with SENSE.ConclusionSENSE imaging at 3T is a reproducible technique for assessing RV and LV structure and function. J. Magn. Reson. Imaging 2008;27:1139–1145. © 2008 Wiley‐Liss, Inc.
Assessment of regional myocardial oxygenation changes in the presence of coronary artery stenosis with balanced SSFP imaging at 3.0T: Theory and experimental evaluation in canines
Authors: Dharmakumar Rohan , Arumana Jain Mangalathu , Tang Richard , Harris Kathleen , Zhang Zhouli , Li Debiao 
Published: April 2008

AbstractPurposeTo examine the dependence of steady‐state free‐precession (SSFP) ‐based myocardial blood‐oxygen‐level‐dependent (BOLD) contrast on field strength using theoretical and experimental models.Materials and MethodsNumerical simulations using a two‐pool exchange model and a surgically prepared dog model were used to assess the SSFP‐based myocardial BOLD signal changes at 1.5T and 3.0T. Experimental studies were performed in eight canines with pharmacological vasodilation under various levels of left circumflex coronary artery stenosis. Experimentally obtained BOLD signal changes were correlated against microsphere‐based true flow changes.ResultsTheoretical results showed that, at 3.0T, relative to 1.5T, a threefold increase in oxygen sensitivity can be expected. Experimental studies in canines showed near similar results—a 2.5 ± 0.2‐fold increase in BOLD sensitivity at 3.0T relative to 1.5T (P < 0.05). Based on the scatter gram of BOLD data and microsphere data, it was found that the minimum regional flow difference that can be detected with SSFP‐based myocardial BOLD imaging at 1.5T and 3.0T were 2.9 and 1.6, respectively (P < 0.05).ConclusionThis study demonstrated that SSFP‐based myocardial BOLD sensitivity is substantially greater at 3.0T compared with 1.5T. The findings here suggest that SSFP‐based myocardial BOLD imaging at 3.0T may have the necessary sensitivity to detect the clinically required minimum flow difference of 2.0. J. Magn. Reson. Imaging 2008;27:1037–1045. © 2008 Wiley‐Liss, Inc.
Effect of vascular stenosis on perfusion‐weighted imaging; differences between calculation algorithms
Authors: Matsushima Shigenori , Kubota Takao , Yamada Kei , Akazawa Kentaro , Masunami Terutoshi , Ito Hirotoshi , Ushijima Yo , Owada Kei , Sasajima Hiroyasu , Mineura Katsuyoshi , Nishimura Tsunehiko 
Published: April 2008

AbstractPurposeTo determine the most suitable postprocessing technique for magnetic resonance (MR) perfusion imaging in patients with vascular stenosis, by comparing the cerebral blood flow (CBF) maps of single photon emission tomography (SPECT) and perfusion MR imaging (MRI).Materials and MethodsIn 15 consecutive patients (14 men and one woman, mean age 73.9 ± 6.0 years) with stenosis of common carotid artery (CCA) or internal carotid artery (ICA) of more than 75%, both brain perfusion MRI and brain perfusion SPECT were performed. From perfusion MR images, CBF maps were calculated with the first moment, singular value decomposition (SVD), and block circulant SVD (b‐SVD) methods, and CBF maps from each algorithm were compared with those from SPECT.ResultsThe b‐SVD method had the best correlation with SPECT (R = 0.814), followed by the first moment method (R = 0.776) and the SVD method (R = 0.723). The b‐SVD method has the least mean difference with SPECT (0.118), the first moment method also had less difference (0.121), and the SVD had greatest mean difference (0.164).ConclusionOur results suggest that in patients with vascular impairment the b‐SVD method will be the technique of choice rather than SVD or first moment method. J. Magn. Reson. Imaging 2008;27:1103–1108. © 2008 Wiley‐Liss, Inc.