bluuebunny/crossref_metadata_2025 huggingface dataset:
Experimental Apoptosis Provides Clues about the Role of Mitochondrial Changes in Neuronal Death
Authors: FATTORETTI PATRIZIA , BERTONI‐FREDDARI CARLO , RECCHIONI RINA , GIORGETTI BELINDA , BALIETTI MARTA , GROSSI YESSICA , SOLAZZI MORENO , CASOLI TIZIANA , DI STEFANO GIUSEPPINA , MARCHESELLI FIORELLA
Published: March 2007

Abstract:  A quantitative morphometric study has been carried out in human neuroblastoma SK‐N‐BE cells to evaluate the ultrastructural features and the metabolic efficiency of mitochondria involved in the early steps of apoptosis. In mitochondria from control and apoptotic cells cytochrome oxidase (COX) activity was estimated by preferential cytochemistry. Number of mitochondria (numeric density: Nv), volume fraction occupied by mitochondria/μm3 of cytoplasm (volume density: Vv), and average mitochondrial volume (V) were calculated for both COX‐positive and ‐negative organelles. The ratio (R) of the cytochemical precipitate area to the overall area of each mitochondrion was evaluated on COX‐positive organelles to estimate the inner mitochondrial membrane fraction actively involved in cellular respiration. Following apoptotic stimulus, the whole mitochondrial population showed a significant increase of Nv and Vv, while V was significantly decreased. In COX‐positive organelles higher values of Nv were found, V appeared significantly reduced, and Vv was unchanged. R was increased at a nonsignificant extent in apoptotic cells. COX‐positive mitochondria accounted for 21% and 35% of the whole population in control and in apoptotic cells, respectively. These findings document that in the early stages of apoptosis the increased fraction of small mitochondria provides an adequate amount of ATP for progression of the programmed cell death and these more efficient organelles appear to represent a reactive response to the loss of metabolically impaired mitochondria. A better understanding of the mitochondrial role in neuronal apoptosis may suggest potential interventions to prevent the extensive nerve cell death typical of neurodegenerative diseases.
Using Janus Green B to Study Paraquat Toxicity in Rat Liver Mitochondria
Authors: GHAZI‐KHANSARI M. , MOHAMMADI‐BARDBORI A. , HOSSEINI M‐J.
Published: March 2007

Abstract:  Janus green B (JG‐B) dye is used for vital staining of mitochondria and its reduction and oxidation shows the electron transfer chain alteration. The defect in electron transfer chain of mitochondria by paraquat is linked to free radical formation. In this present study we compared the abilities of different angiotensin‐converting enzyme inhibitors, captopril (a thiol ACEi), enalapril, and lisinopril (two nonthiol ACEi) on mitochondria toxicity due to paraquat. The rat liver mitochondria were first isolated by centrifuge (at 4°C at a speed of 7,000 g) in a mixture of 0.25 M saccharose solution and 0.05 M Tris buffer. Various concentrations of paraquat (1, 5, 10 mM), enalapril (0.25, 0.5, 1 mM), lisinopril (0.01, 0.05, 0.1 mM), and captopril (0.08, 0.1, 1 mM) on the mitochondria isolated from the liver with respect to time were investigated. Paraquat at a concentration of 5 mM was determined to be significantly different compared to control values (P < 0.05) and captopril at a concentration of 0.08 mM, lisinopril (0.01 mM), and enalapril (0.25 mM) were found not to be significantly different from controls as found by spectroscopy at wavelength of 607 nm. Simultaneous treatment of mitochondria with captopril (0.08 mM) and paraquat (5 mM) significantly ameliorates the mitochondria toxicity of paraquat (5 mM) alone (P < 0.05). Our results show that captopril is a more effective antioxidant than the nonthiol ACEi. Lisinopril (0.01 mM) and enalapril (0.25 mM) did not significantly change the mitochondrial toxicity by paraquat (5 mM) (P > 0.05). The antioxidative action of captopril appears to be attributable to the sulfahydryl group (SH) in the compound. This effect may be due to captopril's abilities to scavenge reactive oxygen species.
Capacitation and Acrosome Reaction in Nonapoptotic Human Spermatozoa
Authors: GRUNEWALD SONJA , BAUMANN THOMAS , PAASCH UWE , GLANDER HANS‐JUERGEN
Published: March 2007

Abstract:  Capacitation and acrosome reaction (AR) of human spermatozoa are prerequisites for fertilization. Annexin‐V‐MACS is able to separate apoptotic from nonapoptotic sperm on the basis of their externalization of phosphatidylserine (EPS). The nonapoptotic (EPS−) fraction is characterized by the lowest amounts of membrane alterations, caspase activation, disrupted mitochondrial potential, and DNA fragmentation. The aim of our study was to investigate the separation effect of Annexin‐V‐MACS on capacitation and AR in nonapoptotic sperm. Semen specimens from 10 healthy donors were separated into 2 samples each, one was left untreated (control) and the second was subjected to Annexin‐V‐MACS. Two aliquots of both, the control as well as the EPS− fraction after Annexin‐V‐MACS, were incubated in HTF at 37°C, 5% CO2 for 3 h either with 3% BSA (capacitation) or without additives. Capacitation was monitored by tyrosine phosphorylation (TyrP) using Western blot technique. AR was determined by labeling with CD46‐FITC before and after stimulation with calcium‐ionophore A23187, followed by flow cytometric evaluation of the percentage of CD46+ sperm. Densitometric analyses of the 105‐kDa and 80‐kDa bands of the TyrP Western blots demonstrated highest TyrP in the capacitated EPS− aliquots. There was no difference in spontaneous AR in all groups. AR was best inducible in EPS‐negative sperm after capacitation. Nonapoptotic human spermatozoa with intact plasma membranes are characterized by superior ability to capacitate and consequently by maximum potential to perform AR after stimulation. Selection of EPS‐negative sperm may be of advantage for assisted reproduction in order to prepare the sperm subpopulation with the highest fertilizing potential.
Experimental Sepsis
Authors: EVI SIMOVART HELLE , AREND ANDRES , TAPFER HELLE , KOKK KERSTI , AUNAPUU MARINA , POLDOJA ELLE , SELSTAM GUNNAR , LIIGANT AADE
Published: March 2007

Abstract:  Sepsis, being characterized by massive translocation of bacteria into tissues, induces the suppression of the function of both leukocytes and macrophages. The aim of the study was to count activated macrophages (AMs) and apoptotic (Ao) cells in the rat spleen during the period of experimental sepsis and to clarify the associations of these parameters with each other and with leukocyte migration and bacterial translocation into different organs. The Wistar rats were intraperitoneally inoculated with Escherichia coli (E. coli) and were sacrificed after 2, 6, 24, 48, and 120 h. Bacteria and leukocytes in tissues were specifically stained. AMs were identified by immunohistological staining and Ao cells by the TUNEL assay. The high counts of E. coli at 6 h were strongly associated with a low level of the total counts of leukocytes, accompanied by the high translocation of microbes into tissues. In the spleen, lymphocytes, macrophages, and neutrophils with pyknotic nuclei were identified. The count of AMs was highest at 24 h after the inoculation with E. coli; at the same time the Ao cell count began to rise and achieved the highest level 24 h later. Our investigation indicates that the molecular peculiarities of macrophages and their responses to the inflammation process are tissue‐specific. In the spleen the activation process involving hematopoietic cells and macrophages was remarkable at the late stage of sepsis, characterized by a high count of Ao cells.
14‐3‐3 Proteins Bind Both Filamin and αLβ2 Integrin in Activated T Cells
Authors: NURMI SUSANNA M. , GAHMBERG CARL G. , FAGERHOLM SUSANNA C.
Published: March 2007

Abstract:  Engagement of the T cell receptor (TCR) initiates intracellular signaling cascades that result in T cell activation, differentiation, acquisition of effector functions, or apoptosis. The signals from the TCR are coupled to distal signaling pathways by adapter proteins leading to dramatic changes in the cytoskeleton, transcription, and activation of integrins, which mediate adhesion. LFA‐1 (leukocyte function‐associated antigen‐1) integrin (αLβ2 or CD11a/CD18) plays an important role in adhesion, for example, by linking extracellular ligands to the actin cytoskeleton. The intracellular tails of integrins contain several phosphorylation sites, making them candidate‐binding partners for 14‐3‐3 proteins, which are adaptor proteins that bind to phosphorylated ligands. In a screen for 14‐3‐3 binding partners in T cells, we identified both β2 integrins and filamin. The integrin β2 chain binds to 14‐3‐3 proteins through phosphorylated Thr758 after TCR ligation and this association regulates integrin‐mediated cell spreading, which is necessary for adhesion. Here, we show that filamin associates with 14‐3‐3 proteins in activated T cells. 14‐3‐3 association with T cell membrane and cytoskeleton proteins after cell stimulation may mediate numerous T cell functions.
SDF‐1 Controls Pituitary Cell Proliferation through the Activation of ERK1/2 and the Ca2+‐Dependent, Cytosolic Tyrosine Kinase Pyk2
Authors: MASSA ALESSANDRO , CASAGRANDE SILVIA , BAJETTO ADRIANA , PORCILE CAROLA , BARBIERI FEDERICA , THELLUNG STEFANO , ARENA SARA , PATTAROZZI ALESSANDRA , GATTI MONICA , CORSARO ALESSANDRO , ROBELLO MAURO , SCHETTINI GENNARO , FLORIO TULLIO
Published: March 2007

Abstract:  Stromal cell‐derived factor‐1 (SDF‐1) is a chemokine of the CXC subfamily that exerts its effects via CXCR4, a G‐protein‐coupled receptor. CXCR4 is often expressed by tumor cells, and its activation causes tumor cell proliferation. Using GH4C1 cells, here we show that SDF‐1 induced cell proliferation in a dose‐dependent manner. Thus, we evaluated the intracellular signaling involved in this effect. SDF‐1 increased cytosolic [Ca2+] and activated Pyk2, ERK1/2, and BKCa channels. To correlate these intracellular effectors with the proliferative activity of SDF‐1, we inhibited their activity using BAPTA‐AM (Ca2+ chelator), PD98059 (MEK inhibitor), salicylate (Pyk2 inhibitor), and TEA (K+ channel blocker). All these compounds reverted SDF‐1‐induced proliferation, suggesting the involvement of multiple intracellular pathways. To identify a possible crosstalk and a molecular ordering among these pathways, we tested these antagonists on SDF‐1‐dependent activation of ERK1/2, Pyk2, and BKCa channels. We report that the inhibition of [Ca2+]i increase or the blockade of BKCa channel activity did not affect ERK1/2 activation by SDF‐1; Pyk2 activation was purely Ca2+‐dependent, not involving ERK1/2 or BKCa channels; and BKCa channel activity was antagonized by Pyk2 but not by ERK1/2 inhibitors. These data suggest that SDF‐1‐dependent increase of [Ca2+]i activates Pyk2, which, in turn, regulates BKCa channel activity. Conversely, ERK1/2 activation is an independent phenomenon. In conclusion, we demonstrate that SDF‐1 induces proliferation of GH4C1 cells, suggesting that the activation of CXCR4 may represent a novel regulatory mechanism for pituitary cell proliferation which may contribute to pituitary adenoma development.
Effects of Chemical Ischemia on Cerebral Cortex Slices
Authors: SINISCALCHI ANNA , CAVALLINI SABRINA , MARINO SILVIA , FALZARANO SOFIA , FRANCESCHETTI LARA , SELVATICI RITA
Published: March 2007

Abstract:  A variety of harmful stimuli, among them energy depletion occurring during transient brain ischemia, are thought to unbalance protein kinase cascades, ultimately leading to neuronal damage. In superfused, electrically stimulated rat cerebral cortex slices, chemical ischemia (CI) was induced by a 5‐min treatment with the mitochondrial toxin, sodium azide (10 mM), combined with the glycolysis blocker, 2‐deoxyglucose (2 mM). Thereafter, 1 h reperfusion (REP) with normal medium followed. Western blot analysis of p21Ras, extracellular signal‐regulated protein kinases (ERK)1/2 (p44/42), phospho‐ERK1/2, mitogen‐activated protein kinase (MAPK)‐p38, phospho‐p38, stress‐activated protein kinases/c‐Jun NH2‐terminal protein kinases (SAPK/JNK), phospho‐SAPK/JNK was carried out. The level of p21Ras was increased by 40% immediately after CI, and did not return to control values following REP. Both ERK1 and ERK2 levels were reduced by CI and recovered to control values following REP; no significant change in their phosphorylation degree (phosphorylated to total level ratio, about 50% in the controls) was observed. Neither p38 levels, nor phosphorylation degree were changed following CI/REP. The activation of SAPK/JNK was significantly reduced under CI, and did not recover following REP. All CI/REP‐induced effects were prevented by the NMDA receptor antagonist MK‐801, 10 μM, suggesting the involvement of glutamate. The present findings show that although CI stimulates the p21Ras protein, MAPK levels and/or phosphorylation are reduced, possibly because of acute energy depletion. Because the activation of SAPK/JNK has been related to both apoptosis and neuroprotection, the decrease observed under CI/REP conditions may instead be related to nonapoptotic neuronal death. These results could be of interest in developing preventive treatments for ischemia/REP‐induced brain damage.
Managing Stock Option Expense: The Manipulation of Option‐Pricing Model Assumptions*
Authors: Johnston Derek
Published: March 2007

This paper examines whether firms that voluntarily recognize stock option expense in their financial statements manage that expense downward more than firms that do not recognize the expense by adjusting option‐pricing model assumptions. To examine this issue, I collect option‐pricing model assumptions from fiscal year 2002 for both a sample of firms that voluntarily recognize stock option expense (“recognizing firms”) and a sample of control firms that do not (“disclosing firms”). The empirical results suggest that recognizing firms manage the recognized stock‐based compensation expense reported in their financial statements downward more than do firms that only disclose the expense. Additional analyses reveal that recognizing firms assume a lower level of volatility than disclosing firms in the option‐pricing model calculations; however, I find no evidence that recognizing firms manage the dividend yield and risk‐free interest rate assumptions more than disclosing firms. The Financial Accounting Standards Board (FASB) recently issued Statement of Financial Accounting Standards No. 123(R), which requires the expensing of the fair value of stock options, so these results may be of interest to capital‐market participants and the FASB as they assess the reliability of stock option expense as determined by option‐pricing models.
Employee Stock Option Fair‐Value Estimates: Do Managerial Discretion and Incentives Explain Accuracy?*
Authors: Hodder Leslie , Mayew William J. , McAnally Mary Lea , Weaver Connie D.
Published: March 2007

We examine the determinants of managers' use of discretion over employee stock option (ESO) valuation‐model inputs that determine ESO fair values. We also explore the consequences of such discretion. Firms exercise considerable discretion over all model inputs, and this discretion results in material differences in ESO fair‐value estimates. Contrary to conventional wisdom, we find that a large proportion of firms exercise value‐increasing discretion. Importantly, we find that using discretion improves predictive accuracy for about half of our sample firms. Moreover, we find that both opportunistic and informational managerial incentives together explain the accuracy of firms' ESO fair‐value estimates. Partitioning on the direction of discretion improves our understanding of managerial incentives. Our analysis confirms that financial statement readers can use mandated contextual disclosures to construct powerful ex ante predictions of ex post accuracy.
The Circumstances and Legal Consequences of Non‐GAAP Reporting: Evidence from Restatements*
Authors: PALMROSE ZOE‐VONNA , SCHOLZ SUSAN
Published: March 2007

Our study examines the circumstances of non‐GAAP financial reporting by 492 U.S. companies that announced restatements from 1995 to 1999. We focus on income statements to analyze the occurrence and resolution of litigation over restatements and explore the role of accounting items in bringing and resolving this litigation. We provide evidence on the pervasiveness of accounting misstatements, describe their nature, and show how, if at all, they affect litigation. We assess the nature of restatements by determining whether regular, recurring earnings from primary operations (core) or other components of earnings (noncore) are misstated, and we assess their pervasiveness by estimating the number of primary accounts misstated. In our sample, companies with core restatements have higher frequencies of intentional misstatements (fraud) and subsequent bankruptcy or delisting. Likewise, these companies have, on average, more material misstatements, more negative security price reactions to restatement announcements, and more negative security price changes over the six months preceding and following restatement announcements. However, controlling for these and other factors, we find a significant association between accounting items and litigation, whether occurrences or resolutions. Specifically, core restatements — driven primarily by misstatements of revenue, a component of core earnings — and more pervasive restatements each play a role, while misstatements of noncore earnings alone do not.
Book Reviews
Authors: SWENSON EDWARD
Published: March 2007

Structure and Meaning in Human Settlements. Tony Atkin and Joseph Rykwert, eds. Philadelphia: University of Pennsylvania Museum of Archaeology and Anthropology, 2005. 370 pp.
Book Reviews
Authors: THOMPSON RICHARD H.
Published: March 2007

Empire at the Margins: Culture, Ethnicity, and Frontier in Early Modern China. Pamela Kyle Crossley, Helen F. Siu, and Donald Sutton, eds. Berkeley: University of California Press, 2006. 378 pp.
Book Reviews
Authors: JORDT INGRID
Published: March 2007

Rebuilding Buddhism: The Theravada Movement in Twentieth‐Century Nepal. Sarah LeVine and David N. Gellner. Cambridge, MA: Harvard University Press, 2005. 377 pp.
Book Reviews
Authors: KAMP KATHRYN
Published: March 2007

Puebloan Ruins of the Southwest. Arthur H. Rohn and William M. Ferguson. Albuquerque: University of New Mexico Press, 2006. 320 pp.
Artificial Curiosities
Authors: Dark Philip J. C.
Published: March 2007

“Artificial Curiosities”, being an exposition of native manufactures coll ected on the three Pacific voyages of Captain James Cook, R.N. at the Bernice Pauahi Bishop Museum, January 18, 1978 – August 31, 1978 on: the occasion of the Bicentennial of the European Discovery of the Hawaiian Islands by Captain Cook – January 18, 1778, by Adrienne Kaeppler. Honolulu, Hawaii: Bishop Museum Press, 293 pp., $27.50.
High-Throughput Identification of Genes Promoting Neuron Formation and Lineage Choice in Mouse Embryonic Stem Cells
Authors: Falk Anna , Karlsson Tobias E. , Kurdija Sanja , Frisén Jonas , Zupicich Joel
Published: March 2007

The potential of embryonic stem cells to differentiate to all cell types makes them an attractive model for development and a potential source of cells for transplantation therapies. Candidate approaches have identified individual genes and proteins that promote the differentiation of embryonic stem cells to desired fates. Here, we describe a rapid large-scale screening strategy for the identification of genes that influence the pluripotency and differentiation of embryonic stem cells to specific fates, and we use this approach to identify genes that induce neuron formation. The power of the strategy is validated by the fact that, of the 15 genes that resulted in the largest increase in neuron number, 8 have previously been implicated in neuronal differentiation or survival, whereas 7 represent novel genes or known genes not previously implicated in neuronal development. This is a simple, fast, and generally applicable strategy for the identification of genes promoting the formation of any specific cell type from embryonic stem cells.

Disclosure of potential conflicts of interest is found at the end of this article.
Studies on the use of offset and angled prescores for fracture control during laser machining of alumina ceramics
Authors: Segall A. E. , Cai G. , Akarapu R.
Published: March 2007

While lasers offer many advantages when machining ceramics, micro- to macroscale damage often culminating in premature fractures is a shortcoming that cannot be ignored by manufacturers, especially during higher-speed machining where supports are not practical. As detailed in earlier studies, such macroscale fractures can be controlled by simultaneously scoring and cutting. Indeed, by using a lower-power beam to simultaneously create a shallow groove or prescore directly ahead of the higher-power cutting beam, the final fracture path can be dictated, even under exaggerated mixed-mode conditions. In this study, the practice of prescoring was extended to include both offset and angled prescores to investigate possible improvements, as well as potential problems associated with poor alignment of the beams. Results indicate that offset beams away from the unsupported end can delay fracture slightly, while offsets toward the free-edge can results in crack bridging and a slightly accelerated fracture. On the other hand, angled prescore tests indicate no real advantages to the practice in part, because material redistribution within the recast layer tends to eliminate the angle. Based on the results of this study, it appears that while precise beam alignment (both angle and offset) is recommended for the highest quality cuts, offsets up to 50% of the beam diameter and slight angles up to 9° off the surface can still work.
Celestite in the Weathering Crust on Limestone Exposed to an Urban Atmosphere in Cracow (Poland)
Authors: Wilczyńska-Michalik Wanda , Michalik Marek
Published: March 2007

Celestite in the Weathering Crust on Limestone Exposed to an Urban Atmosphere in Cracow (Poland)

Celestite containing very low amounts of barium occurs in weathering reaction zones developed on the Pińczów limestone exposed to the polluted atmosphere of Cracow. The mineral occurs both in limestone pore spaces filled with gypsum and in black gypsum crust. The Pińczów limestone contains ca 500 ppm strontium which was released during the reaction with atmospheric pollutants. The nucleation and growth of celestite, requiring significant concentration of components in evaporating solutions, is associated with gypsum crystallization.
The Oak Chronology (948-1314 AD) for the Zary Area (Sw Poland)
Authors: Danek Małgorzata , Kłusek Marzena , Krąpiec Marek
Published: March 2007

The study presents the results of investigations aimed at construction of a site chronology for oak wood from the surroundings of Zary (SW Poland). The 366-year chronology ZY_2006, covering the period 948-1314 AD was determined on the basis of 189 individual ring patterns representing samples of archaeological wooden objects lifted at the excavation works led in the Old Town of Zary in the years 2004-2005. The chronology produced exhibits high similarity to the standards for the neighbouring regions: Wielkopolska and Lower Silesia. The statistical parameters of the chronology are very high and, thanks to the signature years determined, it should be an excellent tool for dating samples of mediaeval timbers from the whole region of Ziemia Lubuska, including some with relatively short dendrochronological sequences.
Dissimilarity analysis based batch process monitoring using moving windows
Authors: Zhao Chunhui , Wang Fuli , Jia Mingxing
Published: March 2007

In recent years, a novel MSPC method known as DISSIM, which is based on the dissimilarity of process time series data, has been developed focusing on continuous and stable processes. However, its further application is hindered because of its unsuitability to batch processes which lie at the heart of many industries. In the present work, combined with variable moving windows, an important extension of the novel DISSIM method, termed EDISSIM, is made for its practical application to batch processes monitoring as well as the theoretical analysis basis for the determination of control limit. Moreover, contribution plots of dissimilarity index are used to identify the variables that contribute significantly to the out‐of‐control state. The applications of the proposed EDISSIM method are illustrated with respect to simulated data collected from both a simple 2 × 2 numerical process and a fed‐batch penicillin fermentation industrial batch process. The results clearly show that it functions very well to successfully detect and diagnose fault in batch processes, which implies the significant investigation potential of the proposed method. © 2007 American Institute of Chemical Engineers AIChE J, 2007
Titelbild: Formation of Gels and Liquid Crystals Induced by Pt⋅⋅⋅Pt and π–π* Interactions in Luminescent σ‐Alkynyl Platinum(II) Terpyridine Complexes (Angew. Chem. 15/2007)
Authors: Camerel Franck , Ziessel Raymond , Donnio Bertrand , Bourgogne Cyril , Guillon Daniel , Schmutz Marc , Iacovita Cristian , Bucher Jean‐Pierre
Published: March 2007

Weiche Platindrähte lassen sich durch Verknüpfung amphiphiler Alkinplattformen mit planaren PtII‐Terpyridin‐Einheiten herstellen. Das Titelbild zeigt Fasern, die durch Stapeln solcher Komplexe über Pt⋅⋅⋅Pt‐ und π–π‐Wechselwirkungen gebildet werden. Man erhält dunkelgrüne Gele und flüssigkristalline Materialien mit Phosphoreszenz im nahen IR. R. Ziessel et al. beschreiben in der Zuschrift auf S. 2713 ff., wie diese Fasern auf hoch geordnetem pyrolytischem Graphit aufgebaut werden (beobachtet durch AFM; Bildhintergrund).
The σ‐CAM Mechanism: σ Complexes as the Basis of σ‐Bond Metathesis at Late‐Transition‐Metal Centers
Authors: Perutz Robin N. , Sabo‐Etienne Sylviane
Published: March 2007

Complexes in which a σ‐HE bond (E=H, B, Si, C) acts as a two‐electron donor to the metal center are called σ complexes. Clues that it is possible to interconvert σ ligands without a change in oxidation state derive from CH activation reactions effecting isotope exchange and from dynamic rearrangements of σ complexes (see Frontispiece). Through these pathways, metathesis of ME bonds can occur at late transition metals. We call this process σ‐complex‐assisted metathesis, or σ‐CAM, which is distinct from the familiar σ‐bond metathesis (typical for d0 metals and requiring no intermediate) and from oxidative‐reductive elimination mechanisms (inherently requiring intermediates with changed oxidation states and sometimes involving σ complexes). There are examples of σ‐CAM mechanisms in catalysis, especially for alkane borylation and isotope exchange of alkanes. It may also occur in silylation and alkene hydrogenation.
Inside Cover: A Nucleoside That Contains a Rigid Nitroxide Spin Label: A Fluorophore in Disguise (Angew. Chem. Int. Ed. 15/2007)
Authors: Barhate Nivrutti , Cekan Pavol , Massey Archna P. , Sigurdsson Snorri Th.
Published: March 2007

A single nucleoside acts as a probe for two complementary spectroscopic techniques. In their Communication on page 2655 ff., S. Th. Sigurdsson and co‐workers describe the synthesis of DNA with a rigid nitroxide spin label. The modified nucleoside forms a stable base pair with guanine and projects the spin label into the major groove of the duplex. The rigidity of the nitroxide enables more accurate measurements of distance and motion in nucleic acids (left), while its reduction yields a fluorescent probe DNA (right).
Einfluss der Eigenspannung auf die Rissbildung bei dicken Bauteilen im jungen Betonalter
Authors: Viet Tue Nguyen , Bödefeld Jörg , Dietz Jörg
Published: March 2007

Entsprechend den geltenden nationalen und internationalen Massivbaunormen darf die in Stahlbetonbauteilen von Bewehrung aufzunehmende Kraft bei überwiegender Zwangbeanspruchung mit zunehmenden Bauteildicken bis auf 50% reduziert werden. Als Begründung werden Eigenspannungen genannt. Die Ergebnisse einer umfangreichen FE‐Untersuchung zu den Eigenspannungen während der Betonerhärtung haben bestätigt, dass der Einfluss der Eigenspannung auf die Risslast mit der Bauteildicke zunimmt. Deren Zusammenhang ist jedoch sehr komplex, so dass die heutige Annahme zur Zwangkraft für die Begrenzung der Rissbreite infolge Zwangbeanspruchung nur als eine pragmatische Vorgehensweise bewertet werden kann. Für einen mechanisch fundierten Bemessungsvorschlag sind weitere Untersuchungen erforderlich.
Weiße Wanne in Additiv‐Bauweise
Authors: Fastabend Michael , Doering Norbert , Nagel Felix
Published: March 2007

Ausgehend von den Hinweisen zur regelkonformen Ausbildung von Weißen Wannen wird an einem konkreten Beispiel gezeigt, dass auch die Verletzung der Konstruktionsregeln zu erfolgreichen Bauwerken führen kann. Aus den geometrischen und grundbaulichen Randbedingungen ergab sich die Notwendigkeit, eine Weiße Wanne mit einer Additivaußenwand sowie einer Bodenplatte mit mannigfachen Festhaltungen auszuführen. Die Additivaußenwand wurde vermittels einer Stahlspundwand sowie einer Betoninnenschale konstruiert. Die Verklammerungen der Gesamtkonstruktion mit dem umgebenden Boden ergaben sich aus der profilierten Außenkante der Spundwand sowie aus den Pfahlgründungen für die Bodenplatte. Besonderheiten bei den Bemessungkonzepten waren insbesondere bei der Additivaußenwand festzustellen. Nicht über das übliche Maß hinausgehende Rissbildungen in Wand und Bodenplatte zeigten die erfolgreiche Umsetzung der speziellen Bauweise einer Weißen Wanne auf.
Fmoc‐2‐mercaptobenzothiazole, for the introduction of the Fmoc moiety free of side‐reactions
Authors: Isidro‐Llobet Albert , Just‐Baringo Xavier , Ewenson Ariel , Álvarez Mercedes , Albericio Fernando
Published: March 2007

A double side‐reaction, consisting in the formation of Fmoc‐β‐Ala‐OH and Fmoc‐β‐Ala‐AA‐OH, during the preparation of Fmoc protected amino acids (Fmoc‐AA‐OH) with Fmoc‐OSu is discussed. Furthermore, the new Fmoc‐2‐MBT reagent is proposed for avoiding these side‐reactions as well as the formation of the Fmoc‐dipeptides (Fmoc‐AA‐AA‐OH) and even tripeptides, which is another important side‐reaction when chloroformates such as Fmoc‐Cl is used for the protection of the α‐amino function of the amino acids. © 2007 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 88: 733–737, 2007.

This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com
Randomized clinical trial of perioperative systemic warming in major elective abdominal surgery
Authors: Wong P F , Kumar S , Bohra A , Whetter D , Leaper D J
Published: March 2007

Background

Hypothermia is common in the operating theatre and may increase susceptibility to postoperative complications. Intraoperative systemic warming has been shown to improve outcomes of surgery. This study aimed to examine the effects of additional perioperative systemic warming on postoperative morbidity.

Methods

All patients admitted for elective major abdominal surgery and fulfilling the inclusion criteria were randomized into control or warming groups. Both groups were warmed during surgery, but patients in the warming group were additionally warmed 2 h before and after surgery using a conductive carbon polymer mattress.

Results

The trial recruited 103 patients (56 in the control group, 47 in the warming group). Both groups were well matched for age, sex and clinical state. Patients in the warming group had lower blood loss (median 200 (range 5–1000) ml versus median 400 (range 50–2300) ml in the control group; P = 0·011) and complication rates (15 (32 per cent) of 47 versus 30 (54 per cent) of 56 in the control group; P = 0·027). There were three deaths; two in the control group (P = 0·566).

Conclusion

Extending systemic warming to the perioperative period had additional beneficial effects, with minimal additional cost and patient discomfort.
Meta-analysis and systematic review of the relationship between volume and outcome in abdominal aortic aneurysm surgery
Authors: Holt P J E , Poloniecki J D , Gerrard D , Loftus I M , Thompson M M
Published: March 2007

Background

This study investigated the volume–outcome relationship for abdominal aortic aneurysm (AAA) surgery and quantified critical volume thresholds.

Methods

PubMed, EMBASE and the Cochrane library were searched for articles on the operation volume–outcome relationship in elective and ruptured AAA surgery. UK Hospital Episode Statistics data were also considered. Elective and ruptured AAA repairs were dealt with separately. The data were meta-analysed, and the odds ratios (95 per cent confidence interval) for mortality at higher- and lower-volume hospitals were compared. Volume thresholds were identified from each paper.

Results

The analysis included 421 299 elective and 45 796 ruptured AAA operations. Significant relationships between mortality and annual volume were noted for both groups. Overall, the weighted odds ratio was 0·66 (0·65 to 0·67) for elective repair at a threshold of 43 AAAs per annum and 0·78 (0·73 to 0·82) for ruptured aneurysm repair at a threshold of 15 AAAs per annum, both in favour of high-volume institutions.

Conclusion

Higher annual operation volumes are associated with significantly lower mortality in both elective and ruptured AAA repair. This suggests that AAA surgery should be performed only at higher-volume centres.
Semiconductor Behavior of a Metal‐Organic Framework (MOF)
Authors: Alvaro Mercedes , Carbonell Esther , Ferrer Belén , Llabrés i Xamena Francesc X. , Garcia Hermenegildo
Published: March 2007

Upon light excitation MOF‐5 behaves as a semiconductor and undergoes charge separation (electrons and holes) decaying in the microsecond time scale. The actual conduction band energy value was estimated to be 0.2 V versus NHE with a band gap of 3.4 eV. Photoinduced electron transfer processes to viologen generates the corresponding viologen radical cation, while holes of MOF‐5 oxidizes N,N,N′,N′‐tetramethyl‐p‐phenylenediamine. One application investigated for MOF‐5 as a semiconductor has been the shape‐selective photocatalyzed degradation of phenol in aqueous solutions.
From Molecule to Bulk Material: Optical Properties of Hydrogen‐Bonded Dimers [C12H12N4O2AgPF6]2 and [C28H28N6O3AgPF6]2 Depend on the Arrangement of the Oxime Moieties
Authors: Cheng Wen‐Dan , Wu Dong‐Sheng , Shen Juan , Huang Shu‐Ping , Xie Zhi , Zhang Hao , Gong Ya‐Jing
Published: March 2007

The dependence of the optical properties of [C12H12N4O2AgPF6]2 (dimer‐1) and [C28H28N6O3AgPF6]2 (dimer‐2) on the arrangement of the oxime moieties in the molecule and in bulk crystals was investigated by means of time‐dependent density functional theory. Dimer‐1 with simple pyridine oxime ligands and a wavy arrangement has a smaller dipole moment and larger transition energy between the two states, and thus smaller third‐order polarizabilities and two‐photon absorption cross sections. Dimer‐2 with extended pyridine oxime ligands and a ladder arrangement has a larger dipole moment and smaller transition energy between the two states, and thus larger third‐order polarizabilities and two‐photon absorption cross sections. The lowest energy absorption band is red‐shifted for dimer‐2 as compared with dimer‐1, due to more pronounced π–π delocalization interactions and weaker hydrogen bonding in dimer‐2. The electronic absorption spectra, frequency‐dependent third‐order polarizabilities, and two‐photon absorption cross sections involve significant contributions from charge transfers from π/π* orbitals of the pyridine oxime ligands but no contribution from PF6− ions or H2O molecules in the wavelength range studied for the monomers and dimers of the C12H12N4O2AgPF6 and C28H28N6O3AgPF6 molecules. The third‐order susceptibilities and two‐photon absorption coefficients of bulk solids were estimated on the basis of the optical properties of the corresponding dimers, and the bulk material constructed from dimer‐2 has the larger optical parameters of the two.
Dienyne Ring‐Closing Metathesis Approach for the Construction of Taxosteroids
Authors: Aldegunde María J. , García‐Fandiño Rebeca , Castedo Luis , Granja Juan R.
Published: March 2007

A cascade dienyne ring‐closing metathesis approach has been applied to the synthesis of the tetracyclic carbon framework of a new class of hybrid compounds—the taxosteroids—possessing carbon frameworks incorporating moieties characteristic of both taxanes (such as AB rings) and steroids (i.e., CD system and side chain). This tandem cyclization is highly stereoselective, allowing the one‐step formation of the bicyclo[5.3.1]undecene system characteristic of taxol. In this work we describe the scope and limitations of such cyclizations.
Sn20.5□3.5As22I8: A Largely Disordered Cationic Clathrate with a New Type of Superstructure and Abnormally Low Thermal Conductivity
Authors: Zaikina Julia V. , Kovnir Kirill A. , Sobolev Alexei V. , Presniakov Igor A. , Prots Yuri , Baitinger Michael , Schnelle Walter , Olenev Andrei V. , Lebedev Oleg I. , Van Tendeloo Gustaaf , Grin Yuri , Shevelkov Andrei V.
Published: March 2007

Sn20.5As22I8, a new cationic clathrate, has been prepared by using an ampoule technique. According to the X‐ray powder diffraction data, it crystallizes in the face‐centered cubic space group F23 or Fm$\bar 3$ with a unit‐cell parameter of a=22.1837(4) Å. Single‐crystal X‐ray data allowed solution of the crystal structure in the subcell with a unit‐cell parameter of a0=11.092(1) Å and the space group Pm$\bar 3$n (R=5.7 %). Sn20.5As22I8 (or Sn20.5□3.5As22I8, accounting for the vacancies in the framework) possesses the clathrate‐I type crystal structure, with iodine atoms occupying the cages of the cationic framework composed of tin and arsenic atoms. The crystal structure is strongly disordered. The main features are a random distribution of vacancies, and shifts of the tin and arsenic atoms away from their ideal positions. The coordination of the tin atoms has been confirmed by using 119Sn Mössbauer spectroscopy. Electron diffraction and high‐resolution electron microscopy (HREM) analyses have confirmed the presence of the superstructure ordering, which results in a doubling of the unit‐cell parameter and a change of the space group from Pm$\bar 3$n to either F23 or Fm$\bar 3$. Analysis of the crystal structure has led to the construction of four ordering models for the superstructure, which have been corroborated by HREM, and has also led to the identification of disordered regions originating from overlap of the different types of ordered domains. Sn20.5As22I8 is a diamagnetic semiconductor with an estimated band gap of 0.45 eV; it displays abnormally low thermal conductivity, with the room temperature value being just 0.5 W m−1 K−1.
Modification of Methylaluminoxane‐Activated ansa‐Zirconocene Catalysts with Triisobutylaluminum—Transformations of Reactive Cations Studied by NMR Spectroscopy
Authors: Babushkin Dmitrii E. , Brintzinger Hans H.
Published: March 2007

When triisobutylaluminum (AliBu3) is added to solutions containing methylaluminoxane (MAO) and rac‐[Me2Si(ind)2ZrCl2] (ind: indenyl) in C6D6, NMR spectra show that methyl‐bridged mixed‐alkylaluminum dimers Al(μ‐Me)2Me4−xiBux predominate. These dimers react with MAO under partial transfer of isobutyl groups and induce a conversion of the initially prevailing cationic trimethylaluminum adduct rac‐[Me2Si(ind)2Zr(μ‐Me)2AlMe2+] to rac‐[Me2Si(ind)2Zr(μ‐Me)2AlMeiBu+] and rac‐[Me2Si(ind)2Zr(μ‐Me)2AliBu2+]. These species are unstable and release isobutene under formation of zirconocene hydrides.
Efficient automated assessment of genetic abnormalities detected by fluorescence in situ hybridization on brush cytology in a Barrett esophagus surveillance population
Authors: Rygiel Agnieszka M. , van Baal Jantine W. P. M. , Milano Francesca , Wang Kenneth K. , ten Kate Febo J. , Fockens Paul , Rosmolen Wilda D. , Bergman Jacques J. G. H. M. , Peppelenbosch Maikel P. , Krishnadath Kausilia K.
Published: March 2007

BACKGROUND.

Automated assessment of genetic abnormalities detected by fluorescence in situ hybridization (FISH) in brush cytology specimens from patients with Barrett esophagus (BE) may enhance the clinical applicability of this methodology. The objectives of this study were to validate a novel, automated, proprietary system (CytoVison SPOT AX) for the assessment of FISH abnormalities in BE brush cytology and, subsequently, to use this automated method for screening of a BE surveillance cohort.

METHODS.

FISH with DNA probes for chromosomes 9, 17, and Y, and for the 9p21 (p16), 17q11.2 (Her2/neu), and 17p13.1 (p53) loci was applied on brush cytology specimens from a surveillance cohort of 151 patients with BE. Validation of the automated system was performed by comparison of the automated FISH results with manual scores for the first 60 patients.

RESULTS.

There was 98% concordance between manual and automated FISH analysis with κ values from 0.49 to 1 for the different probes. The loss of 17p13.1 (p53) was observed in only 5% of patients with no dysplasia (ND) and in 9% of patients with low‐grade dysplasia (LGD) but increased to 46% in patients with high‐grade dysplasia (HGD) (P < .005; Fisher exact test). Chromosomes 9 and 17 were observed in 6% of patients with ND, in 21% of patients with LGD, and in 62% of patients with HGD (P < .05). Ten percent of patients with ND had loss of the Y chromosome, which increased to 27% in patients with HGD (P< .05). The amplification of 17q11.2 (Her2/neu) was detected in 62% of patients with HGD (P < .001).

CONCLUSIONS.

The current investigation indicated that the CytoVison SPOT AX is an objective, efficient system for the analysis of DNA‐FISH on BE brush cytology and is applicable for analyzing large populations of BE patients. In the current study cohort, the loss of 17p13.1 (p53), Y chromosome loss, and polysomy of chromosomes 17 and 9 were correlated with increasing grade of dysplasia in patients with BE. Cancer 2007. © 2007 American Cancer Society.
Chelating η6‐Arene‐η1‐carbene Ligands in Ruthenium Complexes
Authors: Özdemir Ismail , Demir Serpil , Çetinkaya Bekir , Toupet Loïc , Castarlenas Ricardo , Fischmeister Cédric , Dixneuf Pierre H.
Published: March 2007

N‐Heterocyclic carbene (NHC) ruthenium complexes containing a chelating NHC‐η6‐arene ligand have been prepared and evaluated as precursors for ring opening metathesis polymerization (ROMP). The reaction of [RuCl2(p‐cymene)]2 with electron‐rich olefins of the bis(imidazolinylidene) type containing at least one arylmethyl‐N chain (aryl: 2,4,6‐trimethylphenyl, 3,4,5‐trimethoxyphenyl) selectively leads, upon heating, to ruthenium(II) complexes 2 containing a chelating bridged carbene η6‐arene ligand. The reaction of complexes containing an additional ROCH2CH2N group with AgOTf leads to ionic complexes 5 with a tridentate trifunctional carbene/arene/ether ligand. The X‐ray structure of[RuCl2{η1‐CN(CH2{η6‐C6H2Me3‐2,4,6})CH2CH2N(CH2{C6H2(OMe)3‐3,4,5})}] (2c) and that of the ionic ruthenium complex containing a trifunctional carbene/arene/ether ligand that provides ten electrons, [RuCl{η1‐CN(CH2{η6‐C6H2Me3‐2,4,6})CH2CH2N(CH2CH2OCH3)}][CF3SO3] (5e), have been determined. The precursors 2 in the presence of AgOTf and propargyl alcohol, in order to produce an allenylidene initiator, and complexes 5 in the presence of propargyl alcohol lead to ROMP of norbornene. It is shown that initial chloride abstraction is required and that the catalyst activity is increased by using mesityl–ruthenium precursors and coordinated branched ether complexes. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Hydrogenation of a Trinuclear μ3‐Imido Complex of Ruthenium: Homolytic or Heterolytic H–H Bond Cleavage?
Authors: Kameo Hajime , Nakajima Yumiko , Suzuki Hiroharu
Published: March 2007

To elucidate the mode of hydrogen–hydrogen bond cleavage at transition metal sites that cooperate with a heteroatom, the hydrogenation of trinuclear μ3‐imido complex (Cp*Ru)3(μ3‐NH)(μ‐H)3 (Cp* = η5‐C5Me5) (1) with deuterium was carried out. The percentage of deuterium content in the amido ligand of (Cp*Ru)3(μ‐NH2)(μ‐H)4 (2), which was generated as an intermediate in the reaction of 1 with dihydrogen, proved that hydrogenation of 1 to 2 proceeded through homolytic cleavage of dihydrogen.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Novel Sorbicillin Derivatives with an Unprecedented Carbon Skeleton from the Sponge‐Derived Fungus Trichoderma Species
Authors: Neumann Kerstin , Abdel‐Lateff Ahmed , Wright Anthony D. , Kehraus Stefan , Krick Anja , König Gabriele M.
Published: March 2007

Chemical investigation of the fungus Trichoderma sp., isolated from the Caribbean sponge Agelas dispar led to four novel sorbicillinoid polyketide derivatives (1–4) with an unprecedented tricyclic ring system. The structures of all compounds, including the absolute configuration, were determined by interpretation of their spectroscopic data (1D and 2D NMR, CD, MS, UV and IR), and molecular modeling calculations. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)
Coupled hydrodynamic response of concrete gravity dams using finite and infinite elements
Authors: Saini S. S. , Bettess P. , Zienkiewicz O. C.
Published: March 2007

This paper presents the application of the finite element method for analysing the two‐dimensional response of reservoir‐dam systems subjected to horizontal ground motion. The interaction between the dam and the reservoir as well as the compressibility of water has been taken into account. The complete system has been considered to be composed of two substructures, namely the reservoir and the dam. To take into account the large extent of the reservoir, it has been idealized using specially developed infinite elements coupled with standard finite elements while the dam is represented using finite elements alone. Structural damping of the dam and radiation damping in the fluid phase have been accounted for in the analysis. It is concluded that the effect of radiation damping is considerable at high frequencies of excitation. The coupled response of the system is significantly large at and near the fundamental natural frequency of the system in comparison to the uncoupled responses. The method is computationally quite economical, capable of taking into account the arbitrary geometry of the system and is recommended for practical application. Further applications and extensions of the approach to three dimensional analyses are possible.
Response spectrum techniques for asymmetric buildings
Authors: Rutenberg Avigdor , Hsu Tzu‐I. , Tso W. K.
Published: March 2007

A scheme is proposed to calculate the effect of torsion on each lateral load resisting element of asymmetrical buildings in the context of the response spectrum technique. The scheme consists of: (i) Obtain the modal shear and torque on the building by the response spectrum technique, (ii) Compute the total modal shear forces on each frame by resolving the modal shear and torque on the building according to principles of structural mechanics. The shears on each frame due to the lateral load effect and torsional effect are combined algebraically, (iii) Obtain the total shear force on each frame by combining the total modal shears on that frame in a root sum square manner.

Since the proper phase relationship between the lateral load effect and torsional effect is accounted for on a modal basis, it is believed that the proposed scheme provides a more realistic load estimate on the frames than the conventional approach. An example of a simplified mono‐symmetrical frame structure is chosen to illustrate the accuracy of the proposed scheme, using dynamic time‐history analysis as a standard for comparison.