bluuebunny/crossref_metadata_2025_split huggingface dataset:
An ortho‐lithiated derivative of protected phenylboronic acid: an approach to ortho‐functionalized arylboronic acids and 1,3‐dihydro‐1‐hydroxybenzo[c][2,1]oxaboroles
Authors: Da̧browski Marek , Kurach Paweł , Luliński Sergiusz , Serwatowski Janusz 
Published: March 2007

Abstract2‐(2′‐Bromophenyl)‐6‐butyl‐[1,3,6,2]dioxazaborocan, prepared readily by the esterification of 2‐bromophenylboronic acid with N‐butyldiethanolamine (BDEA), undergoes Br/Li exchange using BuLi/THF at − 78 °C. A resulting intermediate proved useful in synthesis of various ortho‐functionalized arylboronic acids. Specifically, reactions with benzaldehydes provide a convenient access to 1,3‐dihydro‐1‐hydroxy‐3‐arylbenzo[c][2,1]oxaboroles that exhibit a remarkably high rotational barrier around the Caryl bond. In addition, the molecular structure of sterically hindered 1,3‐dihydro‐1‐hydroxy‐3‐(2′, 6′‐dimethoxyphenyl)benzo[c][2,1]oxaborole is reported. Copyright © 2007 John Wiley & Sons, Ltd.
The rodent estrous cycle: characterization of vaginal cytology and its utility in toxicological studies
Authors: Goldman Jerome M. , Murr Ashley S. , Cooper Ralph L. 
Published: March 2007

AbstractWhile an evaluation of the estrous cycle in laboratory rodents can be a useful measure of the integrity of the hypothalamic‐pituitary‐ovarian reproductive axis, it can also serve as a way of insuring that animals exhibiting abnormal cycling patterns are disincluded from a study prior to exposure to a test compound. Assessment of vaginal cytology in regularly cycling animals also provides a means to establish a comparable endocrine milieu for animals at necropsy. The procedure for obtaining a vaginal smear is relatively non‐invasive and is one to which animals can become readily accustomed. It requires few supplies, and with some experience the assessments can be easily performed in fresh, unstained smears, or in fixed, stained ones. When incorporated as an adjunct to other endpoint measures, a determination of a female's cycling status can contribute important information about the nature of a toxicant insult to the reproductive system. In doing so, it can help to integrate the data into a more comprehensive mechanistic portrait of the effect, and in terms of risk assessment, may provide some indication of a toxicant's impact on human reproductive physiology. Birth Defects Res (Part B), 2007. Published 2007 Wiley‐Liss, Inc.
Electron‐ and Energy‐Transfer Properties of Hydrophilic Carotenoids
Authors: Sliwka Hans‐Richard , Melø Thor‐Bernt , Foss Bente Jeanette , Abdel‐Hafez Shams H. , Partali Vassilia , Nadolski Geoff , Jackson Henry , Lockwood Samuel F. 
Published: March 2007

AbstractThe antioxidant activities—expressed as the electron‐donating properties—of five hydrophilic carotenoids (carotenoid surfactants) and three related hydrophobic carotenoids were investigated by flash photolysis. The electron‐transfer rates of the carotenoids to the triplet state of the sensitizer 2‐nitronaphthalene and the energy transfer rates of triplet 2‐nitronaphthalene to the carotenoids were determined. The results demonstrate that the electron‐donating effects of the hydrophilic and hydrophobic carotenoids were comparable when evaluated in acetonitrile. In the presence of water, however, electron transfer (i.e., antioxidant efficiency) was enhanced by a factor of four for the hydrophilic carotenoids. The increased hydrophilicity of carotenoids, therefore, could expand their antioxidant properties, thus facilitating their use as aqueous‐phase radical scavengers. At the same time, it was shown that supramolecular assembly (“aggregation”) of the amphiphilic carotenoids prevented electron transfer, thus deactivating the antioxidant function. Modulation of the biophysical properties of carotenoids through synthetic modification is capable of increasing the biological and medical utility of this natural class of predominantly hydrophobic antioxidant compound.
Rearrangement of microtubule polarity orientation during conversion of dendrites to axons in cultured pyramidal neurons
Authors: Takahashi Daisuke , Yu Wenqian , Baas Peter W. , Kawai‐Hirai Rika , Hayashi Kensuke 
Published: March 2007

AbstractAxons and dendrites of neurons differ in the polarity orientation of their microtubules. Whereas the polarity orientation of microtubules in axons is uniform, with all plus ends distal, that in dendrites is nonuniform. The mechanisms responsible for establishment and maintenance of microtubule polarity orientation in neuronal processes remain unclear, however. We previously described a culture system in which dendrites of rat cortical neurons convert to axons. In the present study, we examined changes in microtubule polarity orientation in such dendrites. With the use of the hooking procedure and electron microscopy, we found that microtubule polarity orientation changed from nonuniform to uniform, with a plus end‐distal arrangement, in dendrites that gave rise to axons during culture of neurons for 24 h. Microtubule polarity orientation remained nonuniform in dendrites that did not elongate. Axon regeneration at the dendritic tip thus triggered the disappearance of minus end‐distal microtubules from dendrites. These minus end‐distal microtubules also disappeared from dendrites during axon regeneration in the presence of inhibitors of actin polymerization, suggesting that actin‐dependent transport of microtubules is not required for this process and implicating a previously unidentified mechanism in the establishment and maintenance of microtubule polarity orientation in neuronal processes. Cell Motil. Cytoskeleton 2007. © 2007 Wiley‐Liss, Inc.
Rho plays a central role in regulating local cell‐matrix mechanical interactions in 3D culture
Authors: Lakshman N. , Kim A. , Bayless K. J. , Davis G. E. , Petroll W. M. 
Published: March 2007

AbstractThe purpose of this study was to assess quantitatively the role of the small GTPase Rho on cell morphology, f‐actin organization, and cell‐induced matrix remodeling in 3D culture. Human corneal fibroblasts (HTK) were infected with adenoviruses that express green fluorescent protein (GFP) or GFP‐N19Rho (dominant negative Rho). One day later cells were plated inside collagen matrices and allowed to spread for 24 h. Cells were fixed and stained for f‐actin. Fluorescent (for f‐actin) and reflected light (for collagen fibrils) images were acquired using confocal microscopy. Fourier transform analysis was used to assess local collagen fibril alignment, and changes in cell morphology and collagen density were measured using MetaMorph. The decrease in matrix height was used as an indicator of global matrix contraction. HTK and HTK‐GFP cells induced significant global matrix contraction; this was inhibited by N19Rho. HTK and HTK‐GFP fibroblasts generally had a bipolar morphology and occasional intracellular stress fibers. Collagen fibrils were compacted and aligned parallel to stress fibers and pseudopodia. In contrast, HTK‐GFPN19 cells were elongated, and had a more cortical f‐actin distribution. Numerous small extensions were also observed along the cell body. In addition, both local collagen fibril density and alignment were significantly reduced. Rho plays a key role in regulating both the morphology and mechanical behavior of corneal fibroblasts in 3D culture. Overall, the data suggest that Rho‐kinase dependent cell contractility contributes to global and local matrix remodeling, whereas Rho dependent activation of mDia and/or other downstream effectors regulates the structure and number of cell processes. Cell Motil. Cytoskeleton 2007. © 2007 Wiley‐Liss, Inc.
Microtubule‐binding proteins CLASP1 and CLASP2 interact with actin filaments
Authors: Tsvetkov Andrey S. , Samsonov Andrey , Akhmanova Anna , Galjart Niels , Popov Sergey V. 
Published: March 2007

AbstractCell morphogenesis requires dynamic communication between actin filaments and microtubules which is mediated, at least in part, by direct structural links between the two cytoskeletal systems. Here, we examined interaction between the CLIP‐associated proteins (CLASP) CLASP1 and CLASP2, and actin filaments. We demonstrate that, in addition to a well‐established association with the distal ends of microtubules, CLASP2α co‐localizes with stress fibers, and that both CLASP1α and CLASP2α co‐immunoprecipitate with actin. GFP‐CLASP2α exhibits retrograde flow in the lamellipodia of Xenopus primary fibroblasts and in the filopodia of Xenopus spinal cord neurons. A deletion mapping analysis reveals that both the microtubule‐binding domain of CLASP2 (which is homologous between all CLASPs) and the N‐terminal dis1/TOG domain of CLASP2α (which is homologous between α isoforms) possess actin‐binding activity. Fluorescence resonance energy transfer experiments demonstrate significant energy transfer between YFP‐CLASP2α and CFP‐actin. Our results indicate that CLASPs function as actin/microtubule crosslinkers in interphase cells. We propose that CLASPs facilitate recognition of actin filaments by the plus ends of growing microtubules at the initial stages of actin‐microtubule interaction. Cell Motil. Cytoskeleton 2007. © 2007 Wiley‐Liss, Inc.
Virtual Screening Leads to the Discovery of an Effective Antagonist of Lymphocyte Function‐Associated Antigen‐1
Authors: Shoda Miyuki , Harada Takeo , Yano Kazuo , Stahura Florence L. , Himeno Takeshi , Shiojiri Satoshi , Kogami Yuji , Kouji Hiroyuki , Bajorath Jürgen 
Published: March 2007

AbstractThe binding of lymphocyte function‐associated antigen‐1 (LFA‐1) to its ligand on endothelial cells, intercellular adhesion molecule‐1 (ICAM‐1), is a crucial step in the migration of leukocytes during the early stages of inflammation and is also involved in T‐cell activation. In this paper, we report the identification of a series of novel antagonists of the LFA‐1/ICAM‐1 interaction using ligand‐based virtual screening (VS), analogue design, and structure–activity relationship (SAR) analysis. Candidate compounds were evaluated in protein binding and cell adhesion assays. Experimental evaluation of only 25 candidates selected from a pool of ∼2.5 million database compounds identified an initial hit that could be expanded and converted into a lead that effectively blocked the interaction between LFA‐1 and ICAM‐1.
Measurement of intracellular sodium with NMR methods
Authors: Hutchison Robert B. , Shapiro Joseph I. 
Published: March 2007

AbstractThe measurement and monitoring of intracellular sodium concentrations is critically important to elucidating normal and abnormal cellular physiology. NMR approaches to this problem using 23Na NMR spectroscopy have included detailed analysis of relaxation time constants, the use of chemical shift agents, and detection of multiple‐quantum‐filtered signals. These methods have been applied to isolated cells as well as to perfused organs and in situ tissues. The theoretical framework for as well as the practical applications and limitations of these methods are discussed.
Relaxation time measurements in NMR imaging. Part I: Longitudinal relaxation time
Authors: Kaldoudi Eleni , Williams Steve C. R. 
Published: March 2007

AbstractRelaxation time measurements are important in magnetic resonance imaging. This paper discusses the need for creating calculated relaxation time images and it reviews current practices in the field. Imaging techniques based on inversion recovery, partial saturation, and variable‐tip‐angle experiments, as well as single‐shot methods that employ stimulated echoes or multiple‐readout pulses are considered. Virtues and limitations of each method are reported.
Correlated vector model of multiple‐spin systems
Authors: Lowry David F. 
Published: March 2007

AbstractA vector model correctly predicts the correlated motion of weakly coupled spins. The model is semiclassical when the spins are interacting and fully classical when all spins are transverse and not interacting. A simple two‐pulse experiment and the Heteronuclear Multiple Quantum Coherence (HMQC) experiment are analyzed. The model is extended to the relativistic limit and discussed in the context of the Einstein, Rosen, Podolsky gedanken experiment and the twin paradox.
Curve fitting in nuclear magnetic resonance spectroscopy: Illustrative examples using a spreadsheet and microcomputer
Authors: Irwin Peter L. , Damert William C. , Doner Landis W. 
Published: March 2007

AbstractA simplified explanation of the modified Gauss‐Newton linearization (curve‐fitting) procedure is presented by translating this algorithm into a spreadsheet with examples from various single‐ and multiple‐pulse NMR experiments. Comparisons are made with linear regression analysis of mathematically manipulated data.
Absence of conservation laws and the reciprocity relation in polarization‐transfer experiments
Authors: Zhang Shanmin , Xu Ping , Sørensen Ole W. , Ernst Richard R. 
Published: March 2007

AbstractConservation, creation, and destruction of polarization in nuclear magnetic polarization‐transfer experiments are discussed. In general, polarization is not conserved during NMR pulse experiments, although a useful reciprocity relation is formulated. The features of polarization‐transfer experiments are illustrated by liquid‐ and solid‐state NMR.
Homonuclear and heteronuclear correlation experiments using pulsed‐field gradients
Authors: Tolman Joel R. , Prestegard James H. 
Published: March 2007

AbstractThe underlying theoretical aspects for the application of pulsed‐field gradients to heteronuclear NMR experiments are developed within the density matrix and product operator formalisms. Specific rules allow the straightforward product operator analysis of many pulsed‐field‐gradient NMR experiments. Using these rules, experiments for coherence selection in two‐dimensional NMR spectroscopy are discussed and compared with experiments that use coherence selection by phase cycling. Methods for obtaining pure‐phase lineshapes are discussed in detail. Finally, pulsed‐field‐gradient experiments that achieve resolution and sensitivity comparable to their corresponding phase‐cycled versions are reviewed.
Pulse techniques for CIDNP
Authors: Goez Martin 
Published: March 2007

AbstractThe peculiarities of measurements of chemically induced dynamic nuclear polarization (CIDNP) with pulsed and Fourier transform NMR spectrometers are discussed. If detection is accomplished in this way, new classes of experiments become possible. First, CIDNP net and multiplet effects can be separated by pulse techniques. Second, kinetic measurements (“flash” CIDNP) can be performed with a time resolution in the submicrosecond range. Third, pseudostationary experiments allow recording of time‐independent CIDNP spectra that are free from the effects of nuclear spin relaxation in the products and that possess improved signal‐to‐noise ratios while maintaining excellent suppression of unchanging background magnetization. Finally, signals of unpolarized nuclei in the products can be made observable by means of coherence transfer techniques.
Risk of cerebral metastases and neurological death after pathological complete response to neoadjuvant therapy for locally advanced nonsmall‐cell lung cancer
Authors: Chen Allen M. , Jahan Thierry M. , Jablons David M. , Garcia Joaquin , Larson David A. 
Published: March 2007

AbstractBACKGROUND.The incidence and pattern of brain metastases was analyzed among patients who achieved a pathological complete response (pCR) after neoadjuvant chemotherapy or chemoradiotherapy for locally advanced nonsmall‐cell lung cancer (NSCLC).METHODS.Between 1990 and 2004, 211 patients were treated with neoadjuvant therapy before surgical resection for stage III NSCLC. The clinical course of 51 patients who demonstrated a pCR were reviewed. The neoadjuvant regimen consisted of either chemotherapy (29 patients) or chemoradiotherapy (22 patients). Histology was 45% adenocarcinoma, 41% squamous cell, and 14% large cell carcinoma. No patient received prophylactic cranial irradiation (PCI).RESULTS.Overall survival at 1, 3, and 5 years was 82%, 63%, and 42%, respectively. The most common site of initial recurrence was the brain. Twenty‐two (43%) patients developed brain metastasis as the site of first failure, which represented 71% of all isolated recurrences. Ultimately, 28 (55%) patients developed brain metastases at some point during their clinical course. The 5‐year estimates of brain metastasis‐free survival for patients with squamous and nonsquamous cancers were 57% and 34%, respectively (P = .02). Median survival from the time of brain metastasis was 10 and 5 months for those with isolated and nonisolated recurrences, respectively.CONCLUSION.Patients with a pCR after multimodality therapy for locally advanced NSCLC are at excessively high risk for the subsequent development of brain metastases. Implications for management strategies including PCI and stereotactic radiosurgery (SRS) are discussed. Cancer 2007. © 2007 American Cancer Society.
Male breast cancer in the veterans affairs population
Authors: Nahleh Zeina A. , Srikantiah Roopa , Safa Malek , Jazieh Abdul‐Rahman , Muhleman Albert , Komrokji Rami 
Published: March 2007

AbstractBACKGROUND.The incidence of male breast cancer (MBC) continues to rise. The Veterans Affairs (VA) Central Cancer Registry (VACCR) provides a unique source for the study of MBC. The objective of this retrospective analysis was to compare the characteristics and outcome of patients with MBC and patients with female breast cancer (FBC) in the VA population.METHODS.VACCR data were used to analyze the database of VA patients who had breast cancer diagnosed between 1995 and 2005. It includes 120 VA medical centers. Primary site codes were identified for breast cancer (500–508). Data were entered and analyzed using biostatistical software.RESULTS.In total, 3025 patients' records were reviewed, and 612 patients who had MBC were compared with 2413 patients who had FBC. The mean age at diagnosis was 67 years for patients with MBC and 57 years for patients with FBC (P < .005). More patients with MBC were black, and patients with MBC presented with higher disease stage and more lymph node‐positive disease. The dominant histology in MBC was ductal carcinoma. No difference in grade or laterality was observed. Estrogen and progesterone receptor‐positive tumors were more common in MBC compared with FBC. Overall, patients with MBC received less chemotherapy, whereas no statistical difference was observed in the use of hormone treatment. The median overall survival for patients who had MBC was 7 years compared with 9.8 years for patients who had FBC (log‐rank test; P < .005). There was no statistically significant difference in median survival for patients with stage III disease and stage IV disease. However, the median survival differed significantly for patients with stage I disease and stage II disease. In lymph node‐negative patients, the median survival was 6.1 years for patients with MBC and 14.6 years for patients with FBC (P < .005), whereas the median survival did not differ significantly in lymph node‐positive patients. Using Cox regression analysis age, sex, clinical stage, and lymph node status were independent prognostic factors for survival, whereas race, histology, and grade were not.CONCLUSIONS.To the authors' knowledge, this is the largest series of MBC and FBC to date in the veterans population. The results suggested the presence of differences in the biology, pathology, presentation, ethnicity, and survival between patients with MBC and patients with FBC in the VA population. It is noteworthy that the survival of patients with MBC was inferior for those with early‐stage disease and lymph node‐negative tumors, suggesting that there are differences between the sexes in the pathogenesis and biology of breast cancer. In patients with hormone receptor‐positive MBC, survival was inferior despite similar hormone treatment practices between MBC and FBC. This observational study calls for a better understanding of this disease that would allow new opportunities for specific therapeutic intervention. Cancer 2007. © 2007 American Cancer Society.
A cracked beam finite element for through‐cracked tube
Authors: Schoefs F. , Le Van A. , Rguig M. 
Published: March 2007

AbstractThe reassessment of existing structures leads to analyse the impact of local defects on the structural behaviour. This paper proposes a cracked beam finite element with a view to introducing the effect of large through‐cracks in the structural analysis for framed structures like jacket offshore platforms. The model parameters are identified for several joint typologies using 3D finite element results. Copyright © 2007 John Wiley & Sons, Ltd.
Flow analysis and sorting of microchromosomes (<3 Mb)
Authors: Ng Bee L. , Yang Fengtang , Carter Nigel P. 
Published: March 2007

AbstractBackground:The analysis and isolation of high numbers of chromosomes smaller than 3 Mb in size (microchromosomes) with good purity is dependent primarily on the detection sensitivity of the flow cytometer and the precision of the sort unit. The aim of this study was to investigate the capability of using a conventional flow cytometer for the detection and sorting at high purity microchromosomes with an estimated size of 2.7 Mb.Methods:Chromosomes were isolated from a human cell line containing a pair of X‐derived microchromosomes, using a modified polyamine isolation buffer. The chromosome preparation was labeled with Hoechst and Chromomycin and analyzed and purified using a MoFlo sorter (DAKO) configured for high‐speed sorting. The purity of the flow‐sorted microchromosomes was assessed by reverse chromosome painting.Results:Improved resolution of the peak of microchromosomes in a bivariate plot of Hoechst versus Chromomycin fluorescence was obtainable after discriminating clumps and debris based on gating data within a FSC versus pulse width plot.Conclusions:Chromosomes of smaller size, less than 3 Mb, can be detected with high resolution and flow‐sorted with high purity using a conventional flow sorter. © 2007 International Society for Analytical Cytology
Alterations of centromere positions in nuclei of immortalized and malignant mouse lymphocytes
Authors: Sarkar Rahul , Guffei Amanda , Vermolen Bart J. , Garini Yuval , Mai Sabine 
Published: March 2007

AbstractBackground:The three‐dimensional (3D) positions of centromeres have been studied in several cell systems. However, data on centromere positions during cellular transformation remain elusive. This study has focused on mouse lymphocytes and investigated the centromere positions in primary, immortalized, and tumor cells.Methods:Eighty‐to‐ninety z‐slices of each mouse lymphocyte nucleus were acquired using a sampling distance of 107 nm in the xy plane and 200 nm along z for each z‐stack, using an Axioplan 2 microscope, an AxioCam HR CCD, a 63×/1.4 oil objective, and the Axiovision 3.1 software (Carl Zeiss, Canada). A constrained iterative algorithm (Schaefer et al., J Microsc 2001;204:99–107) was used for deconvolution. Centromere positions in 3D images were analyzed using CentroView, a program we developed to measure nuclear centromere positions.Results:Using CentroView we determined the positions of centromeres in primary lymphocytes, immortalized and malignant mouse B cells. We show that centromeres exhibit altered nuclear positions in immortalized and malignant B cells. These changes are independent of previously described cell cycle‐dependent centromere dynamics.Conclusions:The 3D positions of centromeres are altered during cellular transformation. In lymphocytes, centromeres are found in more central nuclear positions following immortalization and transformation. These nuclear changes reflect structural remodeling of mammalian nuclei during oncogenesis and may impact on the structural organization of chromosomes. How centromeric changes are linked to nuclear remodeling can now be quantitatively examined using the tools of this study. © 2007 International Society for Analytical Cytology