bluuebunny/crossref_metadata_2025_split huggingface dataset:
Antigen presentation and transfer between B cells and macrophages
Authors: Harvey Bohdan P. , Gee Renelle J. , Haberman Ann M. , Shlomchik Mark J. , Mamula Mark J. 
Published: May 2007

AbstractB cells play an active role in directing immunity against specific proteins in part because of their capacity to sequester antigen via B cell receptor (BCR). Our prior findings indicate that B cells can initiate an immune response in vivo to self proteins independent of other antigen‐presenting cells (APC). However, these studies also demonstrated that both dendritic cells and macrophages are important in the ongoing immune response. The present work illustrates a mechanism by which antigen acquired by B cells through BCR is specifically transferred to other APC, in particular, macrophages. The transfer of antigen is dependent on the specificity of BCR and requires direct contact between the cells, but does not require MHC compatibility between the cells and is independent of the activation state of macrophages. Antigen transfer is functional, in that macrophages, which received B cell derived‐antigen, can activate CD4 T cells. Overall, these results define a novel mechanism by which B cells can focus immunity toward a specific antigen and transfer the ability to activate CD4 T cells to other APC.
Alternative Synthesis, Density Functional Calculations and Proton Reactivity Study of a Trinuclear [NiFe] Hydrogenase Model Compound
Authors: Lauderbach Frank , Prakash Raju , Götz Andreas W. , Munoz Marcela , Heinemann Frank W. , Nickel Ulrich , Hess Bernd A. , Sellmann Dieter 
Published: May 2007

AbstractThe trinuclear complex [(‘S2’){Ni(PMe3)}2Fe(CO)(‘S2’)2] (1) {‘S2’2– = 1,2‐benzenedithiolate(2–)} has been reported as a structural as well as functional model for [NiFe] hydrogenases since it contains key structural features of the [NiFe] hydrogenase active site, and is oxidized by protons to give [1]+ and H2. Complex 1 formed as an unexpected product from the reaction of [Fe(CO)2(‘S3’)]2 {‘S3’2– = bis(2‐mercaptophenyl) sulfide(2–)} and [Ni(PMe3)2(‘S2’)]. Both the iron and nickel centers of 1 are chelated by ‘S2’ donors, but not with any ‘S3’ ligand. In order to understand this reaction, the new precursor [Fe(CO)2(siS3)]2 (2) {siS32– = bis(2‐mercapto‐3‐trimethylsilylphenyl) sulfide(2–)} was synthesized. Compound 2 readily loses its CO ligand to give [Fe(CO)(siS3)]2 (3), which consists of two 16 valence electron fragments and could be isolated in the solid state. Conversion of 3 to 2 is feasible with gentle bubbling of CO gas for about 2 min. Treatment of 2 with [Ni(PMe3)2(‘S2’)] resulted exclusively in the formation of complex 1, which confirms that all three ‘S2’ ligands in 1 originate from [Ni(PMe3)2(‘S2’)]. Therefore, an alternative synthesis of 1, which does not involve any ‘S3’ ligand, has been developed. Density functional theory (DFT) calculations suggest that the oxidation states of the metal centers are FeII and NiII and do not change upon oxidation of 1 to [1]+. The unpaired electron in [1]+ is located to a large extent on the nickel atoms and the adjacent thiolate donor functions. The charge, however, is distributed over the whole cluster, main parts residing on the ‘S2’ ligands. Preliminary constant potential coulometric measurements indicate that 1 mediates the reduction of protons to dihydrogen at a mild potential (–0.48 V vs. NHE). Based upon these experimental and theoretical results, plausible mechanisms for this reduction are briefly discussed. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
The Role of Escherichia coliform in the Biomineralization of Calcium Oxalate Crystals
Authors: Chen Long , Shen Yuhua , Jia Rong , Xie Anjian , Huang Bei , Cheng Xiaobin , Zhang Qingfeng , Guo Ruiyong 
Published: May 2007

AbstractThe influence of the common bacterium Escherichia coliform (E. coli) on the nucleation and growth of calcium oxalate (CaOxa) in aqueous solution is studied in order to determine its role in the biomineralization of urinary stones. The results show that CaOxa crystals obtained in the presence of E. coli transform more quickly from calcium oxalate dihydrate (COD) into calcium oxalate monohydrate (COM), and they become even larger, than in the absence of the bacterium. On decreasing the concentration of chemical reagents, in other words increasing the ratio bacterium/CaOxa, except for the more rapid phase transition from COD to COM, the CaOxa particles obtained become larger and more regular with a hexagonal morphology. This suggests that E. coli accelerates the crystallization of COM, which is the most stable crystal phase of CaOxa and the major component of urinary stones. Transmission electron microscopy (TEM) images, electron diffraction (ED) patterns, and Fourier‐transform IR (FTIR) spectra show that the biomineralization process of CaOxa crystals takes place both inside and outside the bacterium, which implies that it is induced by both intracellular biomolecules and the bioorganic secretions of the bacteria. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS‐PAGE) data and UV/Vis spectra show that the proteins bound to the crystal surface with a molecular weight of around 26.5 kDa have tyrosine, tryptophan, or phenylalanine residues. The zeta potential and FTIR spectra are used to investigate the mineralization mechanism of CaOxa with E. coli and show that, the negatively charged biomolecules inside and outside the bacterium interact with Ca2+ ions to provide nucleation sites and then act as modifiers to induce the nucleation, growth, and aggregation of COM crystals. Therefore, we infer that E. coli mineralizes calcium oxalate and plays a role in the formation of urinary stones.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Hypomethylation of PRAME is responsible for its aberrant overexpression in human malignancies
Authors: Schenk Tino , Stengel Sven , Goellner Stefanie , Steinbach Daniel , Saluz Hans Peter 
Published: May 2007

AbstractThe preferentially expressed antigen of melanoma (PRAME) is expressed at high levels in large fractions of human malignancies, e.g., acute myeloid leukemia. Therefore, PRAME is an important marker for diagnosis of various malignant diseases and a relevant parameter for monitoring minimal residual disease. It is supposed to be involved in tumorigenic processes. Because of these important aspects we investigated its transcriptional regulation in detail. Most relevant was a detailed DNA methylation analysis of the PRAME 5′ region by genomic sequencing in correlation with PRAME expression in various human patient samples and cell lines. In combination with DNA‐truncation/transfection experiments with respect to DNA methylation, we show that changes in the methylation pattern in defined parts of the regulatory regions of PRAME are sufficient for its upregulation in cells usually not expressing the gene. © 2007 Wiley‐Liss, Inc.
Water uptake by trees in a riparian hardwood forest (Rhine floodplain, France)
Authors: Sánchez‐Pérez José Miguel , Lucot Eric , Bariac Thierry , Trémolières Michèle 
Published: May 2007

AbstractWater flow in the soil–root–stem system was studied in a flooded riparian hardwood forest in the upper Rhine floodplain. The study was undertaken to identify the vertical distribution of water uptake by trees in a system where the groundwater is at a depth of less than 1 m. The three dominant ligneous species (Quercus robur, Fraxinus excelsior and Populus alba) were investigated for root structure (vertical extension of root systems), leaf and soil water potential (Ψm), isotopic signal (18O) of soil water and xylem sap. The root density of oak and poplar was maximal at a depth of 20 to 60 cm, whereas the roots of the ash explored the surface horizon between 0 and 30 cm, which suggests a complementary tree root distribution in the hardwood forest. The flow density of oak and poplar was much lower than that of the ash. However, in the three cases the depth of soil explored by the roots reached 1·2 m, i.e. just above a bed of gravel. The oak roots had a large lateral distribution up to a distance of 15 m from the trunk. The water potential of the soil measured at 1 m from the trunk showed a zone of strong water potential between 20 and 60 cm deep. The vertical profile of soil water content varied from 0·40 to 0·50 cm3 cm−3 close to the water table, and 0·20 to 0·30 cm3 cm−3 in the rooting zone. The isotopic signal of stem water was constant over the whole 24‐h cycle, which suggested that the uptake of water by trees occurred at a relatively constant depth. By comparing the isotopic composition of water between soil and plant, it was concluded that the water uptake occurred at a depth of 20 to 60 cm, which was in good agreement with the root and soil water potential distributions. The riparian forest therefore did not take water directly from the water table but from the unsaturated zone through the effect of capillarity. Copyright © 2007 John Wiley & Sons, Ltd.
Neuronal protein synuclein γ predicts poor clinical outcome in breast cancer
Authors: Guo Jianping , Shou Chengchao , Meng Lin , Jiang Beihai , Dong Bin , Yao Lihua , Xie Yuntao , Zhang Jianzhi , Chen Yiding , Budman Daniel R. , Shi Yuenian Eric 
Published: May 2007

AbstractSynuclein γ (SNCG), previously identified as a breast cancer‐specific gene (BCSG1), is highly expressed in breast carcinomas but not in normal epithelium. SNCG regulates many pathways in growth and progression of breast cancer. To determine if SNCG is a biomarker for clinical prognosis of breast cancer, we generated a panel of murine monoclonal antibodies (mAbs) against human SNCG and correlated SNCG protein expression in 358 clinical breast cancer specimens with clinical outcome. A panel of 14 mAbs was characterized by ELISA, immunoprecipitation (IP), Western blot, immunocytochemistry and immunohistochemistry. SNCG protein expression was determined in 438 clinical breast specimens by immunohistochemical analysis using mAb 5C5. Expression of SNCG was strongly correlated with the stage, lymph node involvement, metastasis, tumor size and Her‐2 status, but its expression was not associated with ER and PR expression status. While 71.4% of advanced breast cancers were positive for SNCG expression, only 26.8% of Stage I/II breast cancers were positive for SNCG expression and 5.2% of benign hyperplasia expressed SNCG. SNCG protein was not detectable in normal tissue adjacent to breast cancer. After a median follow‐up of 64 months, patients with an SNCG‐positive tumor had a significantly shorter disease‐free survival and overall survival and a high probability of death compared no expression of SNCG. Multivariate analysis demonstrated that SNCG was a strong independent prognostic variable. SNCG is a new unfavorable prognostic marker for breast cancer progression and a potential target for breast cancer treatment. © 2007 Wiley‐Liss, Inc.
Inhibition of Wnt‐2 and galectin‐3 synergistically destabilizes β‐catenin and induces apoptosis in human colorectal cancer cells
Authors: Shi Yihui , He Biao , Kuchenbecker Kristopher M. , You Liang , Xu Zhidong , Mikami Iwao , Yagui‐Beltran Adam , Clement Genevieve , Lin Yu‐Ching , Okamoto Junichi , Bravo Dawn T. , Jablons David M. 
Published: May 2007

AbstractConstitutive activation of the Wnt pathway as a result of APC, AXIN1 or CTNNB1 mutations has been found in most colorectal cancers. For a long time, this aberrant Wnt activation has been thought to be independent of upstream signals. However, recent studies indicate that upstream signals retain their ability to regulate the Wnt pathway even in the presence of downstream mutations. Wnt‐2 is well known for its overexpression in colorectal cancer. Galectin‐3 (Gal‐3), a multifunctional carbohydrate binding protein implicated in a variety of biological functions, has recently been reported to interact with β‐catenin. In this study, we investigated roles of Wnt‐2 and Gal‐3 in the regulation of canonical Wnt/β‐catenin signaling. We found that siRNA silencing of either Wnt‐2 or Gal‐3 expression inhibited TCF‐reporter activity, decreased cytosolic β‐catenin level and induced apoptosis in human colorectal cancer cells containing downstream mutations. More interestingly, we showed that inhibition of both Wnt‐2 and Gal‐3 had synergistic effects on suppressing canonical Wnt signaling and inducing apoptosis, suggesting that aberrant canonical Wnt/β‐catenin signaling in colorectal cancer can be regulated at multiple levels. The combined inhibition of Wnt‐2 and Gal‐3 may be of superior therapeutic advantage to inhibition by either one of them, giving rise to a potential development of novel drugs for the targeted treatment of colorectal cancer. © 2007 Wiley‐Liss, Inc.
Differential DNA methylation associated with hepatitis B virus infection in hepatocellular carcinoma
Authors: Su Pei‐Fen , Lee Te‐Chang , Lin Pei‐Ju , Lee Po‐Huang , Jeng Yung‐Ming , Chen Chien‐Hung , Liang Ja‐Der , Chiou Ling‐Ling , Huang Guan‐Tarn , Lee Hsuan‐Shu 
Published: May 2007

AbstractGene inactivation through DNA hypermethylation plays a pivotal role in carcinogenesis. This study aimed to profile aberrant DNA methylation in different stages of liver disease, namely noncirrhosis, cirrhosis and hepatocellular carcinoma (HCC), and also to clarify the influence of hepatitis B virus (HBV) infection on the aberrant DNA methylation in HCCs. Promoter methylation in p14ARF, p16INK4a, O6‐methylguanine‐DNA methyltransferase (MGMT), glutathione S‐transferase pi (GSTP1) and E‐cadherin (E‐Cad) genes of 58 HCCs paired with adjacent nontumorous tissues was assayed by methylation‐specific PCR. HBV infection was determined using a hepatitis B virus surface antigen (HBsAg) serological assay. The frequency of p16INK4a promoter methylation increased from noncirrhotic, cirrhotic, to HCC tissues (noncirrhotic vs. HCC, p < 0.001), while that of GSTP1 promoter methylation increased in cirrhotic tissues compared to noncirrhotic ones (p = 0.029). The frequency of GSTP1 promoter hypermethylation is significantly higher in HCC than in nontumorous tissues (p = 0.022) from HBsAg‐positive patients, but not the HBsAg‐negative controls (p = 0.289). While the frequency of E‐Cad promoter hypermethylation remained high in both nontumorous tissues and HCCs from HBsAg‐positive patients (p = 0.438), it was lower in HCCs than in nontumorous tissues from HBsAg‐negative patients (p = 0.002). In contrast, the frequency of p16INK4a, MGMT and p14ARF promoter hypermethylation in HCCs was unrelated to HBsAg status. In conclusion, aberrant DNA methylation may begin at different stages of liver disease in a gene‐dependent manner. Moreover, HBV infection may enhance or maintain GSTP1 and E‐Cad promoter methylation and thereby affect hepatocarcinogenesis. © 2007 Wiley‐Liss, Inc.
Alcohol and folate consumption and risk of benign proliferative epithelial disorders of the breast
Authors: Cui Yan , Page David L. , Chlebowski Rowan T. , Beresford Shirley A. , Hendrix Susan L. , Lane Dorothy S. , Rohan Thomas E. 
Published: May 2007

AbstractAlcohol consumption has been associated with increased breast cancer risk and the increase in risk may be attenuated by adequate folate intake. However, their associations with the risk of benign proliferative epithelial disorders (BPEDs) of the breast, possible precursors of breast cancer, are not well understood. To investigate these associations, we conducted a cohort study among 68,132 postmenopausal women participating in the Women's Health Initiative randomized clinical trials. Women were prospectively followed and those reporting a breast procedure (open surgical biopsy or core needle biopsy) had histological sections obtained for central pathology review. A total of 1,792 women with BPED of the breast were identified over an average of 7.8 years of follow‐up. Cox proportional hazards models were used to estimate hazard ratios (HRs) and 95% confidence limits (CLs) for the associations of interest. Compared to nondrinkers, total current alcohol intake of 30 g/day or more was not associated with BPED risk (HR = 0.98, 95% CL = 0.70, 1.38). The risk of BPED was not associated with folate intake from diet (highest vs. lowest quartile: HR = 1.10, 95% CL = 0.96, 1.26), from supplements (yes vs. no: HR = 1.05, 95% CL = 0.96, 1.16) or from all sources combined (highest vs. lowest quartile: HR = 1.11, 95% CL = 0.96, 1.27). Furthermore, there was no effect modification between alcohol and folate in relation to the risk of BPED. In conclusion, we observed that alcohol consumption and folate intake were not associated with altered risk of BPED, and that there was no effect modification between them in relation to the risk of BPED. © 2007 Wiley‐Liss, Inc.
The falsity of the reconstruction conjecture for tournaments
Authors: Stockmeyer Paul K. 
Published: May 2007

AbstractThe conjecture that for all sufficiently large p any tournament of order p is uniquely reconstructable from its point‐deleted subtournaments is shown to be false. Counterexamples are presented for all orders of the form 2n + 1 and 2n + 2. The largest previously known counterexamples were of order 8.
The spanning subgraphs of eulerian graphs
Authors: Boesch F. T. , Suffel C. , Tindell R. 
Published: May 2007

AbstractIt is shown that a connected graph G spans an eulerian graph if and only if G is not spanned by an odd complete bigraph K(2m + 1, 2n + 1). A disconnected graph spans an eulerian graph if and only if it is not the union of the trivial graph with a complete graph of odd order. Exact formulas are obtained for the number of lines which must be added to such graphs in order to get eulerian graphs.
The combinatorial map color theorem
Authors: Ringel Gerhard 
Published: May 2007

AbstractThis paper is written in the spirit of the author's book: Map Color Theorem (1974). We try to develop the Map Color Theorem in a combinatorial way, circumventing the unwieldy embedding theory. Similar (but not identical) generalizations have recently and independently been developed by Alpert (in press) and by Stahl (in press). The first nine theorems are one‐dimensional versions of known facts from the theory of two‐dimensional compact manifolds. Theorems 10 to 13 are to my knowledge completely new results.
The number of connected sparsely edged graphs
Authors: Wright E. M. 
Published: May 2007

AbstractAn (n, q) graph has n labeled points, q edges, and no loops or multiple edges. The number of connected (n, q) graphs is f(n, q). Cayley proved that f(n, n‐1) = nn−2 and Renyi found a formula for f(n, n). Here I develop two methods to calculate the exponential generating function of f(n, n + k) for particular k and so to find a formula for f(n, n + k) for general n. The first method is a recurrent one with respect to k and is well adapted for machine computation, but does not itself provide a proof that it can be continued indefinitely. The second (reduction) method is much less efficient and is indeed impracticable for k greater than 2 or 3, but it supplies the missing proof that the generating function is of a particular form and so that the first method can be continued for all k, subject only to the capacity of the machine.
On the independence ratio of a graph
Authors: Albertson Michael O. , Hutchinson Joan P. 
Published: May 2007

AbstractThis paper presents some recent results on lower bounds for independence ratios of graphs of positive genus and shows that in a limiting sense these graphs have the same independence ratios as do planar graphs. This last result is obtained by an application of Menger's Theorem to show that every triangulation of a surface of positive genus has a short cycle which does not separate the graph and is non‐contractible on that surface.
On cycle—Complete graph ramsey numbers
Authors: Erdös P. , Faudree R. J. , Rousseau C. C. , Schelp R. H. 
Published: May 2007

AbstractA new upper bound is given for the cycle‐complete graph Ramsey number r(Cm, Kn), the smallest order for a graph which forces it to contain either a cycle of order m or a set of n independent vertices. Then, another cycle‐complete graph Ramsey number is studied, namely r(⩽Cm, Kn) the smallest order for a graph which forces it to contain either a cycle of order / for some / satisfying 3⩽/⩽m or a set of n independent vertices. We obtain the exact value of r(⩽Cm Kn) for all m > n and an upper bound which applies when m is large in comparison with log n.
Mixed ramsey numbers: Chromatic numbers versus graphs
Authors: Benedict James M. , Chartrand Gary , Lick Don R. 
Published: May 2007

AbstractFor positive integers n1, n2, …, nI and graphs GI+1, GI+2, …, Gk, 1 ≤ / < k, the mixed Ramsey number χ(n1, …, n1, GI+1, …, Gk) is define as the least positive integer p such that for each factorization Kp = F1⊕ … ⊕ F⊕ FI+1⊕ … ⊕ Fk, it it follows that χ(Fi) ≥ ni for some i, 1 ⩽ i ⩽ l, or Gi is a subgraph of Fi for some i, l < i ⩽ k. Formulas are presented for maxed Ramsey numbers in which the graphs GI+1, GI+2, …, Gk are connected, and in which k = I+1 and GI+1 is arbitray.
Some connected ramsey numbers
Authors: Faudree R. J. , Schelp R. H. 
Published: May 2007

AbstractA graph G is co‐connected if both G and its complement Ḡ are connected and nontrivial. For two graphs A and B, the connected Ramsey number rc(A, B) is the smallest integer n such that there exists a co‐connected graph of order n, and if G is a co‐connected graph on at least n vertices, then A ⩽ G or B ⩽ Ḡ. If neither A or B contains a bridge, then it is known that rc(A, B) = r(A, B), where r(A, B) denotes the usual Ramsey number of A and B. In this paper rc(A, B) is calculated for some pairs (A, B) when r(A, B) is known and at least one of the graphs A or B has a bridge. In particular, rc(A, B) is calculated for A a path and B either a cycle, star, or complete graph, and for A a star and B a complete graph.
When the cartesian product of directed cycles is Hamiltonian
Authors: Trotter William T. , Erdös Paul 
Published: May 2007

AbstractThe cartesian product of two hamiltonian graphs is always hamiltonian. For directed graphs, the analogous statement is false. We show that the cartesian product Cn1 × Cn2 of directed cycles is hamiltonian if and only if the greatest common divisor (g.c.d.) d of n1 and n2 is at least two and there exist positive integers d1, d2 so that d1 + d2 = d and g.c.d. (n1, d1) = g.c.d. (n2, d2) = 1. We also discuss some number‐theoretic problems motivated by this result.
Perfect Elimination and Chordal Bipartite Graphs
Authors: Golumbic Martin Charles , Goss Clinton F. 
Published: May 2007

AbstractWe define two types of bipartite graphs, chordal bipartite graphs and perfect elimination bipartite graphs, and prove theorems analogous to those of Dirac and Rose for chordal graphs (rigid circuit graphs, triangulated graphs). Our results are applicable to Gaussian elimination on sparse matrices where a sequence of pivots preserving zeros is sought. Our work removes the constraint imposed by Haskins and Rose that pivots must be along the main diagonal.
Achiral plane trees
Authors: Wormald Nicholas 
Published: May 2007

AbstractHarary and Robinson showed that the number an of achiral planted plane trees with n points coincides with the number pn of achiral plane trees with n points, for n ⩾ 2. They posed the problem of finding a natural structural correspondence which explains this coincidence. In the present paper this problem is answered by constructing two‐to‐one correspondences from certain sets of binary sequences to each of the sets of trees concerned, giving a structural basis for the equation 2an = 2pn. Answers are also supplied to similar correspondence‐type problems of Harary and Robinson, concerning planted plane trees, and achiral rooted plane trees. In addition, each of these four types of plane trees are counted with numbers of points and endpoints as the enumeration parameters. The results all show a symmetry with respect to the number of endpoints which is not shared by the set of all plane trees.