bluuebunny/crossref_metadata_2025 huggingface dataset:
Novel interactions of fission yeast kinesin 8 revealed through in vivo expression of truncation alleles
Authors: West Robert R. , McIntosh J. Richard
Published: June 2008

Fission yeast expresses two kinesin 8s, klp5+ and klp6+, which are important for diverse cellular functions: mitosis, meiosis, and the maintenance of normal cell morphology. During vegetative growth these motors display complex localization patterns, moving from the cytoplasm during interphase to the kinetochores in early mitosis, the interpolar spindle in anaphase B, and then back into the cytoplasm. We have expressed GFP‐tagged alleles of domains from these motors, seeking the signals required for their localizations. The tail of Klp5p localized to the interphase nucleus, more specifically to telomeres. Addition of the neck re‐directed this fragment to microtubules in the cytoplasm. Klp6‐tail and the neck‐tail domains of both motors localized at microtubule ends. Klp6‐neck‐tail localized to the spindle in early mitosis but to the pole‐proximal ends of the spindle in anaphase B. The Klp5‐motor and motor‐neck localized to microtubules, often causing them to bundle. Over‐expression of Klp6‐motor or motor‐neck resulted in shorter microtubules. These localization patterns were no different when constructs were expressed in strains lacking either or both of the endogenous, full‐length proteins. Our results indicate that the localization signals for these kinesins are not derived from simple amino acid sequences but from complex interactions among multiple domains of each motor. Cell Motil. Cytoskeleton 2008. © 2008 Wiley‐Liss, Inc.
A minor β‐tubulin essential for mammalian cell proliferation
Authors: Bhattacharya Rajat , Frankfurter Anthony , Cabral Fernando
Published: June 2008

Mammals use tubulin from multiple genes to construct microtubules. Some genes are expressed in a tissue specific manner, while others are expressed in almost all cell types. β5‐Tubulin is a minor, ubiquitous isoform whose overexpression was recently shown to disrupt microtubules. Using inhibitory RNA, we now report that suppression of β5 production in both human and hamster cells blocks cell proliferation. Cells depleted of β5 either trigger the mitotic checkpoint and undergo apoptosis; or they experience a transient mitotic block, a high incidence of lagging chromosomes, and progression into G1 without cytokinesis to become large, flat cells with elevated DNA content. Microtubules appear to be normally organized in cells depleted of β5, but they are rich in acetylated α‐tubulin indicating that they may be more stable than normal. The results provide the first evidence that a specific isoform of β‐tubulin is required for mitosis. Cell Motil. Cytoskeleton 2008. © 2008 Wiley‐Liss, Inc.
The impact of ethnicity on the presentation and prognosis of patients with gastric adenocarcinoma
Authors: Al‐Refaie Waddah B. , Tseng Jennifer F. , Gay Greer , Patel‐Parekh Lina , Mansfield Paul F. , Pisters Peter W. T. , Yao James C. , Feig Barry W.
Published: June 2008

BACKGROUND.

Regional‐based studies have indicated that ethnicity is associated with presentation and outcome in patients with gastric adenocarcinoma. To validate this observation in a large cohort, the authors of this report used the National Cancer Data Base (NCDB) to determine whether self‐reported ethnicity influences presentation and survival in this patient population.

METHODS.

Patient demographics, tumor‐related features, and treatment‐related features were analyzed by ethnicity. Univariate analyses were performed using the chi‐square test. Overall median and relative survival rates were examined by using the Kaplan‐Meier method. Cox proportional‐hazards models were used to identify the predictors of survival outcomes.

RESULTS.

Between 1995 and 2002, 81,095 cases of gastric adenocarcinoma were entered into the NCDB. There were 57,943 white patients (71.5%), 11,094 African‐American patients (13.7%), 5665 Hispanic patients (7%), 4736 Asian/Pacific Islander (API) patients (5.8%), and 1657 patients of other ethnicities (2%). Significant differences were observed according to ethnicity among the variables that were compared (all P < .01). In patients with stage I and II disease, the 5‐year relative survival rates for APIs (stage I, 77.2%; stage II, 48%) were more favorable than for whites (stage I, 58.7%; stage II, 32.8%), African Americans (stage I, 55.9%; stage II, 37.9%), and Hispanics (stage I, 60.8%; stage II, 39.3%). The overall median survival of APIs was more favorable than that of others (P < .01). Predictors of a better outcome were Asian race, female sex, younger age, earlier stage, lower grade, distal tumors, multimodality treatment, and care at a teaching hospital.

CONCLUSIONS.

Ethnicity was associated with differences in presentation and outcome of patients with gastric adenocarcinoma. APIs had a more favorable outcome than patients of other ethnicities. Further studies should target underlying biologic and socioeconomic factors to explain these differences. Cancer 2008. © 2008 American Cancer Society.
Critical assessment of tools to predict clinically insignificant prostate cancer at radical prostatectomy in contemporary men
Authors: Chun Felix K.‐H. , Haese Alexander , Ahyai Sascha A. , Walz Jochen , Suardi Nazareno , Capitanio Umberto , Graefen Markus , Erbersdobler Andreas , Huland Hartwig , Karakiewicz Pierre I.
Published: June 2008

BACKGROUND.

Overtreatment of prostate cancer (PCa) is a concern, especially in patients who might qualify for the diagnosis of insignificant prostate cancer (IPCa). The ability to identify IPCa prior to definitive therapy was tested.

METHODS.

In a cohort of 1132 men a nomogram was developed to predict the probability of IPCa. Predictors consisted of prostate‐specific antigen (PSA), clinical stage, biopsy Gleason sum, core cancer length and percentage of positive biopsy cores (percent positive cores). IPCa was defined as organ‐confined PCa (OC) with tumor volume (TV) <0.5 cc and without Gleason 4 or 5 patterns. Finally, an external validation of the most accurate IPCa nomogram was performed in the same group.

RESULTS.

IPCa was pathologically confirmed in 65 (5.7%) men. The 200 bootstrap‐corrected predictive accuracy of the new nomogram was 90% versus 81% for the older nomogram. However, in cutoff‐based analyses of patients who were qualified by our and the older nomograms as high probability for IPCa, respectively 63% and 45% harbored aggressive PCa variants at radical prostatectomy (Gleason score 7‐10, ECE, SVI, and/or LNI).

CONCLUSIONS.

Despite a high accuracy, currently available models for prediction of IPCa are incorrect in 10% to 20% of predictions. The rate of misclassification is even further inflated when specific cutoffs are used. As a consequence, extreme caution is advised when statistical tools are used to assign the diagnosis of IPCa. Cancer 2008. © 2008 American Cancer Society.
Multipolar Ordering in Electro‐ and Magnetostatic Coupled Nanosystems
Authors: Vedmedenko Elena Y. , Mikuszeit Nikolai
Published: June 2008

Electric and magnetic multipole moments and polarizabilities are important quantities in studies of intermolecular forces, non‐linear optical phenomena, electrostatic, magnetostatic or gravitational potentials and electron scattering. The experimental determination of multipole moments is difficult and therefore the theoretical prediction of these quantities is important. Depending on purposes of the investigation several different definitions of multipole moments and multipole–multipole interactions are used in the literature. Because of this variety of methods it is often difficult to use published results and, therefore, even more new definitions appear. The first goal of this review is to give an overview of mathematical definitions of multipole expansion and relations between different formulations. The second aim is to present a general theoretical description of multipolar ordering on periodic two‐dimensional lattices. After a historical introduction in the first part of this manuscript the static multipole expansion in cartesian and spherical coordinates as well as existing coordinate transformations are reviewed. On the basis of the presented mathematical description multipole moments of several symmetric charge distributions are summarized. Next, the established numerical approach for the calculation of multipolar ground states, namely Monte Carlo simulations, are reviewed. Special emphasis is put on the review of ground states in multipolar systems consisting of moments of odd or even order. The last section is devoted to the magnetization reversal in dense packed nanomagnetic arrays, where the magnetic multipole–multipole interactions play an important role. Comparison between the theory and recent experimental results is given.
Normalization of bone marrow aspirates for hemodilution in flow cytometric analyses
Authors: Loken Michael R. , Chu Sung‐Chao , Fritschle Wayne , Kalnoski Michael , Wells Denise A.
Published: June 2008

The use of flow cytometric enumeration of blasts in bone marrow aspirates has been of limited value in situations where blood contamination of the specimen is present. Assessment of sequential pulls of bone marrow aspirates from the same patient show decreasing proportions of blasts that are detected in later specimens. To address this problem, the intensity of CD16 on maturing neutrophils was compared for bone marrow biopsies, peripheral blood, and bone marrow aspirates. A comparison between bone marrow biopsy and aspirate specimens from the same individuals showed similar proportions of neutrophils with mature phenotype in most, but not all pairs. Other cell populations (total mature lymphocytes, monocytes, neutrophils, and blasts) were also similar between the two specimen types, with one exception of a patient with myelodysplasia, exhibiting a unique blast population in the biopsy that was not evident in the aspirate. The proportion of mature myeloid cells expressing a mature neutrophil phenotype (high levels of CD16) was found to be 17% (± 6.7, n = 47) in trephine marrow biopsy specimens. In contrast, marrow aspirates contained more of the mature neutrophil phenotype (38% ± 16, n = 33) with about 1/3 of the aspirates indistinguishable from biopsies. Using a simple formula to normalize the aspirate specimens to the average neutrophil composition of marrow biopsies, it was possible to correct for the dilutional effect of added blood to both normal bone marrow aspirates and aspirates with elevated blast counts. These results suggest three alternative means of circumventing the problem of blood dilution of marrow aspirate specimens. (1) Blast counts by flow cytometry can be obtained from disaggregated biopsy specimens. (2) A bone marrow aspirate can be assessed for the proportion of mature neutrophils present and only those with low proportions (<30%) of phenotypic mature neutrophils are considered adequate for blast counting. (3) The aspirates with high proportions of mature neutrophils may be normalized based on the proportion of dim CD16 maturing myeloid cells to a level observed in bone marrow biopsies (based on an average mature neutrophil composition). Such an approach for identifying the amount of hemodilution in each specimen may enhance the utility of flow cytometry in enumeration of blasts in bone marrow, especially in cases where myeloblast count is crucial for prognosis, such as myelodysplastic syndromes (MDS). © 2008 Clinical Cytometry Society
Standardization of flow cytometric minimal residual disease evaluation in acute lymphoblastic leukemia: Multicentric assessment is feasible
Authors: Dworzak Michael Norbert , Gaipa Giuseppe , Ratei Richard , Veltroni Marinella , Schumich Angela , Maglia Oscar , Karawajew Leonid , Benetello Allessandra , Pötschger Ulrike , Husak Zvenyslava , Gadner Helmut , Biondi Andrea , Ludwig Wolf‐Dieter , Basso Giuseppe
Published: June 2008

Background:

Single‐laboratory experience showed that flow cytometric (FCM) assessment of minimal residual disease (MRD) in acute lymphoblastic leukemia (ALL) is feasible in most patients and gives independent prognostic information. It is, however, not known whether FCM analysis can reliably be standardized for multicentric application.

Methods:

An extensive standardization program was installed in four collaborating laboratories, which study FCM‐MRD in children treated with the AIEOP‐BFM‐ALL 2000 protocol. This included methodological alignment, continuous quality monitoring, as well as personnel education by exchange and performance feed‐back.

Results:

Blinded inter‐laboratory tests of list‐mode data interpretation concordance (n = 202 blood and bone marrow samples from follow‐up during induction of 31 randomly selected patients of a total series of n = 395) showed a very high degree of inter‐rater agreement among the four centers despite differences in cytometers and software usage (intraclass correlation coefficient [ICC] 0.979 based on n= 800 single values). Lower concordance was reached with amounts of MRD below 0.1%. Comparing data from sample exchange experiments (n = 42 samples; ICC 0.98) and from independent patient cohorts from the four centers (regarding positive samples per time‐point of follow‐up as well as risk estimates) concordance was also good.

Conclusion:

MRD‐evaluation by FCM in ALL can be standardized for reliable multicentric assessment in large trials. © 2008 Clinical Cytometry Society.
Increased LDL cholesterol and CRP in infants of mothers with type 1 diabetes
Authors: Lindegaard Marie L. S. , Svarrer Eva M. M. , Damm Peter , Mathiesen Elisabeth R. , Nielsen Lars B.
Published: June 2008

Background

Proatherogenic stimuli during foetal life may predispose to development of atherosclerosis in adulthood. Elevated plasma low‐density lipoprotein (LDL) cholesterol and C‐reactive protein (CRP) expression is associated with increased risk of atherosclerosis.

Methods and Results

In this study, we examined how maternal type 1 diabetes affects foetal plasma LDL cholesterol and CRP. In comparison with healthy mothers, the plasma LDL cholesterol was not increased in the mothers with diabetes, however, the umbilical‐cord plasma LDL cholesterol was increased in their infants. CRP was increased in infants of mothers with diabetes and high haemoglobin A1c (HbA1c, ≥ 6.2%). Human placenta expresses microsomal triglyceride transfer protein (MTP), which facilitates secretion of apolipoprotein B‐containing lipoproteins. Microsomal triglyceride transfer activity was slightly higher (11%) in placentas from mothers with diabetes and HbA1c ≥ 6.2% compared with the controls.

Conclusion

The results suggest that maternal type 1 diabetes increases the foetal plasma LDL cholesterol and CRP concentration and thus might predispose the offspring to development of atherosclerosis. Copyright © 2008 John Wiley & Sons, Ltd.
1,25‐Dihydroxyvitamin D improved the free fatty‐acid‐induced insulin resistance in cultured C2C12 cells
Authors: Zhou Qiu Gen , Hou Fan Fan , Guo Zhi Jian , Liang Min , Wang Guo Bao , Zhang Xun
Published: June 2008

Background

Epidemiological evidence has indicated that vitamin D deficiency increased the risk of insulin resistance in metabolic syndrome. The present study was conducted to test the hypothesis that 1,25‐dihydroxyvitamin D may improve the free fatty‐acid (FFA)‐induced insulin resistance in muscle cells.

Method

The insulin resistance of muscle cell model was established by treatment of FFA in differentiated C2C12 cells. Glucose uptake of C2C12 myotubes was analysed by the 3H‐labelled 2‐deoxyglucose uptake assay. The diameter of myotubes was measured under the condition of glutaraldehyde‐induced autofluorescense. Tyrosine phosphorylated insulin receptor substrate 1 (IRS‐1) was measured by immunoprecipitation. Serine phosphorylated IRS‐1 and protein kinase B (Akt), extracellular signal‐related kinase (ERK), c‐Jun amino‐terminal kinases (JNK) as well as their phosphorylated form were analysed by Western blots.

Results

Compared with a vehicle‐treated group, FFA treatment in myotubes was associated with 70.6% reduction in insulin‐mediated uptake of glucose, a five‐fold increase in serine phosphorylation of IRS‐1, 76.9% decrease in tyrosine phosphorylation of IRS‐1 and 81.8% decrease in phosphorylation of Akt. Supplement of 1,25‐dihydroxyvitamin D improved the FFA‐induced inhibition of glucose uptake in a dose‐ dependent (p < 0.001) and time‐dependent manner (p < 0.01). This was accompanied by increase in tyrosine phosphorylation of IRS‐1 and phosphorylated Akt and decrease in serine phosphorylation of IRS‐1 (p < 0.001). 1,25‐Dihydroxyvitamin D also inhibited the FFA‐induced reduction in myotube diameter by 35.3% (p < 0.001). JNK phosphorylation was reduced by 126.7% with treatment of 1,25‐dihydroxyvitamin D (p < 0.001). 1,25‐Dihydroxyvitamin D had no effect on FFA‐induced ERK phosphorylation (p = 0.84).

Conclusion

1,25‐Dihydroxyvitamin D improved the FFA‐induced insulin resistance in muscle cells. Copyright © 2008 John Wiley & Sons, Ltd.
Polysialic acid controls NCAM‐induced differentiation of neuronal precursors into calretinin‐positive olfactory bulb interneurons
Authors: Röckle Iris , Seidenfaden Ralph , Weinhold Birgit , Mühlenhoff Martina , Gerardy‐Schahn Rita , Hildebrandt Herbert
Published: June 2008

Understanding the mechanisms that regulate neurogenesis is a prerequisite for brain repair approaches based on neuronal precursor cells. One important regulator of postnatal neurogenesis is polysialic acid (polySia), a post‐translational modification of the neural cell adhesion molecule NCAM. In the present study, we investigated the role of polySia in differentiation of neuronal precursors isolated from the subventricular zone of early postnatal mice. Removal of polySia promoted neurite induction and selectively enhanced maturation into a calretinin‐positive phenotype. Expression of calbindin and Pax6, indicative for other lineages of olfactory bulb interneurons, were not affected. A decrease in the number of TUNEL‐positive cells indicated that cell survival was slightly improved by removing polySia. Time lapse imaging revealed the absence of chain migration and low cell motility, in the presence and absence of polySia. The changes in survival and differentiation, therefore, could be dissected from the well‐known function of polySia as a promoter of precursor migration. The differentiation response was mimicked by exposure of cells to soluble or substrate‐bound NCAM and prevented by the C3d‐peptide, a synthetic ligand blocking NCAM interactions. Moreover, a higher degree of differentiation was observed in cultures from polysialyltransferase‐depleted mice and after NCAM exposure of precursors from NCAM‐knockout mice demonstrating that the NCAM function is mediated via heterophilic binding partners. In conclusion, these data reveal that polySia controls instructive NCAM signals, which direct the differentiation of subventricular zone‐derived precursors towards the calretinin‐positive phenotype of olfactory bulb interneurons. © 2008 Wiley Periodicals, Inc. Develop Neurobiol, 2008
Sustainable development and the ‘governance challenge’: the French experience with Natura 2000
Authors: McCauley Darren
Published: June 2008

Sustainable development is conceptualized in this paper as a serious challenge for governance structures and processes in nation states. Global and European agreements have placed the inclusion of civil society actors in policy‐making at the heart of the sustainability agenda. This commitment is particularly evident in the Commission's White Paper on Governance and the EU Sustainable Development Strategy. From this perspective, the European Commission has consistently underlined the integral role of dialogue with social partners in any sustainability agenda. In contrast, there is a clear mismatch between these principles of civil society inclusion and policy‐making in France. Long‐standing traditions of meso‐corporatism have struggled to adapt to extending participation to civil society actors. This paper assesses the implementation of sustainable development as civil society inclusion with reference to the French experience in dealing with EU biodiversity policy. It is argued that this governance challenge has effectively presented nation states with an ‘interpretation dilemma’ with regards to sustainable development. Copyright © 2008 John Wiley & Sons, Ltd and ERP Environment.
Cationic Triple‐Decker Complexes with a Bridging 4‐Borataborepine Ligand: Synthesis, Structure, and Bonding
Authors: Mutseneck Elena V. , Wadepohl Hubert , Kudinov Alexander R. , Siebert Walter
Published: June 2008

Cationic 30 VE triple‐decker complexes [Cp*Ru(μ‐η7:η7‐C5B2Me6H)ML]+[ML = Co(C4Me4) (3a), RuCp* (4a), Rh(cod) (7a), and Ir(cod) (8a)] with a bridging hexamethyl‐4‐borataborepine ligand were obtained by electrophilic stacking of the sandwich compound Cp*Ru(η7‐C5B2Me6H) (2a) with [ML]+complex fragments. The reaction of the phenyl‐substituted derivative Cp*Ru(η7‐7‐PhC5B2Me5H) (2b) with [(C4Me4)Co(MeCN)3]+selectively affords the triple‐decker complex [Cp*Ru(μ‐η7:η7‐7‐PhC5B2Me5H)Co(C4Me4)]+(3b), whereas a similar reaction with [Cp*RuCl]4/TlBF4produces a 1:3 mixture of cations, the triple‐decker [Cp*Ru(μ‐η7:η7‐7‐PhC5B2Me5H)RuCp*]+(4b) and the arene‐coordinated [Cp*Ru(μ‐η6:η7‐7‐PhC5B2Me5H)RuCp*]+(5). Stacking of Cp*Ru(η7‐7‐PhCH2C5B2Me5H) (2c) with [CpRu(MeCN)3]+selectively gives the triple‐decker complex [Cp*Ru(μ‐η7:η7‐7‐PhCH2C5B2Me5H)RuCp]+(6c). The dinuclear cations3–8were isolated as deep‐colored air‐stable salts with [BF4]–or [PF6]–anions in moderate to high yields. Structures of3bPF6,4aBF4,7aBF4, and8aBF4were confirmed by X‐ray diffraction studies. Energy decomposition analysis of complexes CpRu(ring) and [CpRu(ring)RuCp]+(ring = Cp, C5BH6, C5B2H7) revealed that the insertion of BH units makes the bonding between [ring]–and [RuCp]+more covalent. According to Mulliken population analysis, weakening of π‐donation and strengthening of δ‐back donation occur in the same order. The electrostatic character of the bond and the contribution of σ‐donation to the covalent bonding are higher in the case of bifacially bonded rings. The boron‐containing triple‐decker complexes are considerably more stable than the cyclopentadienyl analog. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Polymer‐Mediated Growth of Highly Crystalline Nano‐ and Micro‐Sized LiNi0.5Mn1.5O4 Spinels
Authors: Arrebola José Carlos , Caballero Alvaro , Hernán Lourdes , Morales Julián
Published: June 2008

The use of polymers containing oxygen‐based functional groups [polyethylene glycol (PEG), poly(methyl methacrylate) (PMMA)] has been studied to synthesize highly crystalline nanometric LiNi0.5Mn1.5O4 spinel. Polyvinylidene fluoride (PVDF), which was also tested, failed in the spinel synthesis. Mechanical activation of hydrated salts in the presence of oxalic acid and the polymer, followed by heating at 800 °C for a few minutes, is sufficient to obtain pseudopolyhedral particles ranging from 60–80 nm in size. X‐ray broadening analysis and the electron micrographs of the microstructure reveal that the polymer has an improved particle crystallinity. Calcining at 400 °C tailors the particle shape towards a nanorod‐like morphology due to the nonionic surfactant properties of PEG. The ability of the functional groups of these polymers to bind to metal ions brings them closer and therefore shortens the diffusion paths followed to adopt the spinel structure. At high temperature, the particles adopt a well‐defined pseudopolyhedral morphology with a smooth texture and a lower microstrain content than that obtained in the absence of polymer. The results of the electrochemical tests show that the polymer‐assisted nanoparticles exhibit improved reversible capacity and better cycling properties as electrode materials in lithium cells. The improved crystallinity of the particles is the key factor in this respect, particularly when the cells are operated at low rates.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Characterization and chemometric study of crude and refined oils from table olive by‐products
Authors: Ruiz‐Méndez M. Victoria , López‐López Antonio , Garrido‐Fernández Antonio
Published: June 2008

Table olive processing produces defective fruits and the conditioning operations give rise to solid by‐products which are processed to obtain oil. In this study, the most relevant characteristics of crude oils extracted from table olive by‐products were high average acidity values (4.5%, green olives; 8.1%, ripe olives), ECN42 values of 0.34 (green olives) and 0.10 (ripe olives), while 2‐mono‐palmitin averaged 0.92%. The overall content of sterols was 2257 mg/kg (green olives) and 1746 mg/kg (ripe olives), while the concentration of cholesterol was 36 mg/kg (green olives) and 19 mg/kg (ripe olives). The effect of refining was mainly reflected by a decrease in acidity and sterols. Although most characteristics were in agreement with the established regulation for olive oil, the overall trans fatty acid content, the low apparent β‐sitosterol content, and the relatively high cholesterol content prevented their inclusion into classes of crude or refined lampante or pomace olive oils, not even into the vegetable oil category. Therefore, the oils analyzed should be considered for non‐edible purposes. The physicochemical characteristics used for chemometric discrimination permitted discrimination among types of oils (crude, 100%; physically refined, 90%; chemically refined, 100%), elaboration styles (green and ripe olives, 100%) and cultivars (Gordal, Manzanilla, Hojiblanca and Cacereña, 100%), with the sterol composition being the most useful parameter for discrimination.
Imino‐Diels–Alder Reactions of 1‐Aryl‐3‐(trialkylsiloxy)‐1,3‐butadienes in Solution and the Solid Phase
Authors: Caballero Esther , Figueroa Javier , Puebla Pilar , Peláez Rafael , Tomé Fernando , Medarde Manuel
Published: June 2008

Imino‐Diels–Alder reactions between 1‐aryl‐ or 1‐heteroaryl‐3‐(trialkylsiloxy)‐1,3‐butadienes and imines derived from ethyl glyoxylate have been studied. When an achiral imine was used, the diastereoselectivity depended on the nature of the aryl or heteroaryl system; diastereoselectivities > 90 % were observed with methoxyphenyl or indolyl substituents, but were much lower for nitro substituents. High diastereoselectivities were also achieved if a chiral imine derived from methylbenzylamine was used as the dienophile. Solid‐supported imine dienophiles yielded the N‐deprotected cycloadducts by direct cleavage from the resin with no diastereoselectivity. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Synthesis of New Polycyclic γ‐ and δ‐Lactones upon Activation of, and Nucleophilic Additions to, Diazines: Influence of the Activating Agents
Authors: Garduno‐Alva A. , Xu Y. , Gualo‐Soberanes N. , Lopez‐Cortes J. , Rudler H. , Parlier A. , Ortega‐Alfaro M. C. , Alvarez‐Toledano C. , Toscano R. A.
Published: June 2008

The reaction of bis(trimethylsilyl)ketene acetals 2 with N‐heterocycles containing either one or two nitrogen atoms in the presence of triflic anhydride has been examined and the structures of the resulting products compared with those obtained by using methyl chloroformate as the activating agent. Whereas pyridine, pyrazine, quinoxaline and pyrimidine led to the same type of fused δ‐ or γ‐lactones 4, 6, 8, 10 and 11 as with methyl chloroformate, the behaviour of pyridazine appeared to be peculiar. In the presence of methyl chloroformate, this heterocycle led to δ‐lactones 16 via stable dihydropyridazines, with triflic anhydride, the direct formation of γ‐lactones 20 was observed. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Use of Allenylphosphonates as New Substrates for Phosphane‐Catalyzed [3+2] and [4+2] Annulations
Authors: Panossian Armen , Fleury‐Brégeot Nicolas , Marinetti Angela
Published: June 2008

The suitability of allenylphosphonates as substrates in phosphane‐catalyzed annulation reactions has been investigated. Despite their lower reactivity relative to allenyl esters, allenylphosphonates overall display the anticipated behavior: pyrrolines, tetrahydropyridines, and cyclopentenes bearing phosphoryl functions were obtained from imines, α,β‐unsaturated esters, and enones in Bu3P‐ or iBu3P‐promoted reactions. Enantioselective variants of these cyclization reactions afforded enantiomeric excesses of up to 90 % when phosphepine A2 was used as the chiral catalyst. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
2H‐Pyrrole Derivatives from an Aza‐Nazarov Reaction Cascade Involving Indole as the Neutral Leaving Group
Authors: Ghavtadze Nugzar , Fröhlich Roland , Würthwein Ernst‐Ulrich
Published: June 2008

Trifluoromethyl‐substituted N‐indolinyl‐1‐aza‐1,4‐dien‐3‐ones 4, which are accessible in good yields from indolinylimino esters 6 in a two‐step procedure, undergo a novel type of aza‐Nazarov cyclization if treated with strong acids to give the hitherto unknown 3‐hydroxy‐5H‐pyrrole derivatives 8a–p. The solvent‐free polyphosphoric acid/acyl anhydride system as the acidic reaction medium is especially efficient and requires only short reaction times. According to quantum chemical calculations the key step in the reaction cascade is the cleavage of the N–N bond of the hydrazone fragment of a protonated N‐(indolin‐1‐yl)‐1‐aza‐1,4‐dien‐3‐one intermediate such as 10. This intermediate releases 3H‐indole as an unusual, but very efficient neutral leaving group. Several 1‐aza‐1,4‐dien‐3‐ones 4 and some 3‐hydroxy‐5H‐pyrrole derivatives 8 were characterized by X‐ray diffraction.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Separation of α‐, β‐, γ‐, δ‐tocopherols and α‐tocopherol acetate on a pentaerythritol diacrylate monostearate‐ethylene dimethacrylate monolith by capillary electrochromatography
Authors: Chaisuwan Patcharin , Nacapricha Duangjai , Wilairat Prapin , Jiang Zhengjin , Smith Norman W.
Published: June 2008

This work reports the first use of a monolith with method development for the separation of tocopherol (TOH) compounds by CEC with UV detection. A pentaerythritol diacrylate monostearate‐ethylene dimethacrylate (PEDAS‐EDMA) monolithic column has been investigated for an optimised condition to separate α‐, β‐, γ‐ and δ‐TOHs, and α‐tocopherol acetate (TAc). The PEDAS‐EDMA monolith showed a remarkably good selectivity for separation of the TOH isomers including the β‐ and γ‐isomers which are not easily separated by standard C8 or C18 particle‐packed columns. Retention studies indicated that an RP mechanism was involved in the separation on the PEDAS‐EDMA column, but polar interactions with the underlying ester and hydroxyl groups enhanced the separation of the problematic β‐ and γ‐isomers. Separation of all the compounds was achieved within 25 min using 3:10:87 v/v/v 100 mM Tris buffer (pH 9.3)/methanol/ACN as the mobile phase. The method was successfully applied to a pharmaceutical sample with recoveries from 93 to 99%. Intraday and interday precisions (%RSD) for peak area and retention time were less than 2.3. LODs for all four TOHs and TAc were below 1 ppm.
Analysis of disulphide linkages in bovine κ‐casein oligomers using two‐dimensional electrophoresis
Authors: Holland John W. , Deeth Hilton C. , Alewood Paul F.
Published: June 2008

Disulphide bonds play an important role in protein structure and function. Bovine κ‐casein (κ‐csn), an important glycoprotein in milk, contains two cysteines that can form disulphide bonds. On 2‐D gels run under nonreducing conditions the κ‐csn in milk presented a complex pattern of monomers and disulphide‐linked oligomers. Trains of spots corresponding to monomers to hexamers were observed as a result of the participation of different glycoforms and phosphoforms in oligomer formation. The dimers and trimers ran as doublets on the gel and analysis of the disulphide‐linked peptides released from them after in‐gel tryptic digestion showed they were the result of different disulphide linkages. The linkages were confirmed by MSMS. When milks with electrophoretically distinct genetic variants of κ‐csn were mixed and run on 2‐D gels, they retained their distinct patterns indicating that disulphide exchange reactions or disulphide ‘scrambling’ was not occurring during 2‐D analysis. The patterns observed represent the native distribution of κ‐csn in milk at harvest. The role and significance of the disulphide bonding of κ‐csn are discussed.
Microfluidic electroporation for selective release of intracellular molecules at the single‐cell level
Authors: Bao Ning , Wang Jun , Lu Chang
Published: June 2008

Analysis of intracellular materials at the single‐cell level presents opportunities for probing the heterogeneity of a cell population. Lysis by electroporation has been gaining popularity as a rapid method for disruption of the cell membrane and release of intracellular contents. In this report, we selectively released specific intracellular molecules for interrogation at the single‐cell level by tuning the parameters of electroporation. We examined the release of a small molecule, calcein (MW˜600), and a 72‐kDa protein kinase, Syk, tagged by enhanced green fluorescent protein (EGFP) from chicken B cells during electroporation at the single‐cell level. We studied the effects of the field intensity and the field duration on the release of the two molecules. We found that calcein in general was released at lower field intensities and shorter durations than did SykEGFP. By tuning the electrical parameters, we were able to deplete calcein from the cells before SykEGFP started to release. This approach potentially provides a high‐throughput alternative for probing different intracellular molecules at the single‐cell level compared to chemical cytometry by eliminating complete disruption of the cell membrane.
Study of protein binding and micellar partition of highly hydrophobic molecules in a single system using capillary electrophoresis
Authors: Liu Shufang , Wang Hailin , Song Maoyong , Yin Junfa , Jiang Guibin
Published: June 2008

The measurement of protein binding of highly hydrophobic molecules is challenging due to poor solubility and strong adsorption, and further complicated by the competition of lipophilic partition in biological systems. Here, an attempt is presented to simultaneously simulate protein binding and lipophilic partition of hydrophobic molecules in a single system using CE. In this system, the incorporated biocompatible micelles also facilitate the protein binding study of hydrophobic molecules by enhancing their solubility (27 to 104times) and eliminating the problematic adsorption. An equation is derived to describe the competition of protein binding and lipophilic partition and to estimate the protein binding constants in nonmicellar aqueous solution. Five polycyclic aromatic hydrocarbons (PAHs) and HSA were used as model hydrophobic compounds and protein, respectively. The study of the competition between lipophilic partition and protein binding reveals that the binding of the PAHs to HSA is governed by hydrophobic interactions and such binding (except naphthalene) can be eliminated by the lipophilic partition in the nonionic surfactant Tween‐20. The developed method may be extended to evaluate the interactions of various macromolecules (receptors, enzymes, proteins, and DNA/RNA) and hydrophobic molecules.
Confinement effects on the morphology of photopatterned porous polymer monoliths for capillary and microchip electrophoresis of proteins
Authors: He Mei , Zeng Yong , Sun Xuejun , Harrison D. Jed
Published: June 2008

We find that the morphology of porous polymer monoliths photopatterned within capillaries and microchannels is substantially influenced by the dimensions of confinement. Porous polymer monoliths were prepared by UV‐initiated free‐radical polymerization using either the hydrophilic or hydrophobic monomers 2‐hydroxyethyl methacrylate or butyl methacrylate, cross‐linker ethylene dimethacrylate and different porogenic solvents to produce bulk pore diameters between 3.2 and 0.4 µm. The extent of deformation from the bulk porous structure under confinement strongly depends on the ratio of characteristic length of the confined space to the monolith pore size. The effects are similar in cylindrical capillaries and D‐shaped microfluidic channels. Bulk‐like porosity is observed for a confinement dimension to pore size ratio >10, and significant deviation is observed for a ratio <5. At the extreme limit of deformation a smooth polymer layer ˜300 nm thick is formed on the surface of the capillary or microchannel. Surface tension or wetting also plays a role, with greater wetting enhancing deformation of the bulk structure. The films created by extreme deformation provide a rapid and effective strategy to create robust wall coatings, with the ability to photograft various surface chemistries onto the coating. This approach is demonstrated through cationic films used for electroosmotic flow control and neutral hydrophilic coatings for electrophoresis of proteins.
Isoelectric focusing in an ordered micropillar array
Authors: Dauriac Virginie , Descroix Stéphanie , Chen Yong , Peltre Gabriel , Sénéchal Hélène
Published: June 2008

An original micropillar array dedicated to electrophoretic separations has been developed. It consists of a rectangular zone of PDMS micropillars protruding on a PDMS block. This area has been chosen to mimic a diluted gel structure and remains uncovered to keep the ability to perform an immunoblot after the protein separation for further applications in the field of allergy diagnosis. The micropillar array geometry has been optimized by evaluating the influence of pillar shape, pillar size and interpillar distance on evaporation and IEF separation. The separation conditions namely electrolyte composition, temperature and sample loading have been studied. Finally a protein mixture with pI ranging from 4.7 to 10.6 has been successfully separated within this microdevice by IEF without decreasing the resolving power obtained with conventional minigel. The micropillar array developed for electrophoretic separations leads to much shorter analysis times and can be reused several times while gels are disposable.
Flow resistance in steep mountain streams
Authors: Reid Donald E. , Hickin Edward J.
Published: June 2008

Resistance to flow at low to moderate stream discharge was examined in five small (12–77 km2 drainage area) tributaries of Chilliwack River, British Columbia, more than half of which exhibit planar bed morphology. The resulting data set is composed of eight to 12 individual estimates of the total resistance to flow at 61 cross sections located in 13 separate reaches of five tributaries to the main river. This new data set includes 625 individual estimates of resistance to flow at low to moderate river stage. Resistance to flow in these conditions is high, highly variable and strongly dependent on stage. The Darcy–Weisbach resistance factor (ff) varies over six orders of magnitude (0·29–12 700) and Manning's n varies over three orders of magnitude (0·047–7·95). Despite this extreme range, both power equations at the individual cross sections and Keulegan equations for reach‐averaged values describe the hydraulic relations well. Roughness is divided into grain and form (considered as all non‐grain sources) components. Form roughness is the dominant component, accounting for about 90% of the total roughness of the system (i.e., form roughness is on average 8.6 times as great as grain roughness). Of the various quantitative and qualitative form‐roughness indicators observed, only the sorting coefficient (σ = D84/D50) correlates well with form roughness. Copyright © 2008 John Wiley & Sons, Ltd.
Spatial analysis of stream power using GIS: SLk anomaly maps
Authors: Pérez‐Peña J. V. , Azañón J. M. , Azor A. , Delgado J. , González‐Lodeiro F.
Published: June 2008

The stream length‐gradient index (SL) shows the variation in stream power along river reaches. This index is very sensitive to changes in channel slope, thus allowing the evaluation of recent tectonic activity and/or rock resistance. Nevertheless, the comparison of SL values from rivers of different length is biased due to the manner in which the index is formulated, thus making correlations of SL anomalies along different rivers difficult. Therefore, when undertaking a comparison of SL values of rivers of different lengths, a normalization factor must be used. The graded river gradient (K) has already been used in some studies to normalize the SL index. In this work, we explore the relationships between the graded river gradient (K), the SL index and the stream power, proposing the use of a re‐named SLk index, which enables the comparison of variable‐length rivers, as well as the drawing of SLk anomaly maps. We present here a GIS‐based procedure to generate SLk maps and to identify SLk anomalies. In order to verify the advantages of this methodology, we compared an SLk map of the NE border of the Granada basin with both simple river profile–knickpoint identification and with an SL map. The results show that the SLk map supplies good results with defined anomalies and suitably reflects the main tectonic and lithological features of the study area. Copyright © 2008 John Wiley & Sons, Ltd.
Channel degradation and slope adjustment in steep streams controlled through bed sills
Authors: Martín‐Vide J. P. , Andreatta A.
Published: June 2008

General, parallel and rotational degradation and the effect of bed sills are investigated with the aid of historical field data and laboratory experiments. The case under consideration is a system of two tributaries and a main river in northeast Spain, characterized by its short length, steepness and ephemeral nature. The comparison of bed profiles since 1962 revealed an incision greater than 5·5 m. The main causes of degradation are thought to be channelization (width reduction) and urban growth. The equilibrium slopes with and without sills were obtained in 111 live‐bed flume tests. It is demonstrated that the bed slope is milder with sills than without sills under the same flow and sediment rates. The equations for the calculation of equilibrium slopes, scaled to prototype, are applied to the case‐study, with good agreement. Copyright © 2008 John Wiley and Sons, Ltd.
Effects of terrain smoothing on topographic shielding correction factors for cosmogenic nuclide‐derived estimates of basin‐averaged denudation rates
Authors: Norton Kevin P. , Vanacker Veerle
Published: June 2008

Estimation of spatially averaged denudation rates from cosmogenic nuclide concentrations in sediments depends on the surface production rates, the scaling methods of cosmic ray intensities, and the correction algorithms for skyline, snow and vegetation shielding used to calculate terrestrial cosmogenic nuclide production. While the calculation of surface nuclide production and application of latitude, altitude and palaeointensity scaling algorithms are subjects of active research, the importance of additional correction for shielding by topographic obstructions, snow and vegetation is the subject of ongoing debate. The derivation of an additional correction factor for skyline shielding for large areas is still problematic. One important issue that has yet to be addressed is the effect of the accuracy and resolution of terrain representation by a digital elevation model (DEM) on topographic shielding correction factors. Topographic metrics scale with the resolution of the elevation data, and terrain smoothing has a potentially large effect on the correction of terrestrial cosmogenic nuclide production rates for skyline shielding. For rough, high‐relief landscapes, the effect of terrain smoothing can easily exceed analytical errors, and should be taken into account. Here we demonstrate the effect of terrain smoothing on topographic shielding correction factors for various topographic settings, and introduce an empirical model for the estimation of topographic shielding factors based on landscape metrics. Copyright © 2008 John Wiley and Sons, Ltd.
Sub‐cell shock capturing and spacetime discontinuity tracking for nonlinear conservation laws
Authors: Palaniappan J. , Miller S. T. , Haber R. B.
Published: June 2008

We describe two approaches to resolving shocks and other discontinuities in spacetime discontinuous Galerkin (SDG) methods for nonlinear conservation laws. The first is an adaptation of the sub‐cell shock‐capturing technique, recently introduced by Persson and Peraire, to the special circumstances of SDG solutions constructed on causal spacetime grids. We restrict the stabilization operator to spacetime element interiors, thereby preserving the 𝒪(N) computational complexity and the element‐wise conservation properties of the basic SDG method, and use a special discontinuity indicator to limit the stabilization to elements traversed by discontinuous solution features. The method resolves discontinuities within individual spacetime elements having a sufficiently high‐order basis. Numerical studies demonstrate the combination of sub‐cell shock capturing with h‐adaptive spacetime meshing that circumvents the projection errors inherent to purely spatial remeshing procedures.

In a second method, we use adaptive spacetime meshing operations to track the trajectories of singular surfaces while maintaining the quality of the surrounding mesh. We present a series of feasibility studies where we track shocks and contact discontinuities in solutions to the inviscid Euler equations, including an example where the trajectories are not known a priori. The SDG‐tracking method sharply resolves discontinuities without mesh refinement and requires very little stabilization. Copyright © 2008 John Wiley & Sons, Ltd.
Parallel three‐dimensional simulation of the injection molding process
Authors: Araújo B. J. , Teixeira J. C. F. , Cunha A. M. , Groth C. P. T.
Published: June 2008

This paper describes the development of a parallel three‐dimensional unstructured non‐isothermal flow solver for the simulation of the injection molding process. The numerical model accounts for multiphase flow in which the melt and air regions are considered to be a continuous incompressible fluid with distinct physical properties. This aspect avoids the complex reconstruction of the interface. A collocated finite volume method is employed, which can switch between first‐ and second‐order accuracy in both space and time. The pressure implicit with splitting of operators algorithm is used to compute the transient flow variables and couple velocity and pressure. The temperature equation is solved using a transport equation with convection and diffusion terms. An upwind differencing scheme is used for the discretization of the convection term to enforce a bounded solution. In order to capture the sharp interface, a bounded compressive high‐resolution scheme is employed. Parallelization of the code is achieved using the PETSc framework and a single program multiple data message passing model. Predicted numerical solutions for several example problems are considered. The first case validates the solution algorithm for moderate Reynolds number flows using a structured mesh. The second case employs an unstructured hybrid mesh showing the capability of the solver to describe highly viscous flows closer to realistic injection molding conditions. The final case presents the non‐isothermal filling of a thick cavity using three mesh sizes and up to 80 processors to assess parallel performance. The proposed algorithm is shown to have good accuracy and scalability. Copyright © 2008 John Wiley & Sons, Ltd.