bluuebunny/crossref_metadata_2025_split huggingface dataset:
Presidential Succession in Ecuador, 1830-1970
Authors: Maier Georg 
Published: March 2007

An article by Professors Richard B. Gray and Frederick R. Kirwin entitled “Presidential Succession in Chile: 1817-1966” and subsequent correspondence with one of the coauthors encouraged me to write a similar study on Ecuador. In researching the available material on the subject I can well appreciate the reasons for the great lack of comparative data on the Latin American presidency and the need for additional studies on this subject.Of the few sources available on Ecuador's presidents no two provide exactly the same information. This pertains to biographical data as well as to time served in the executive office. There is even disagreement as to who served at a given time. Some of these discrepancies are the result of the turbulent events of the first three decades of Ecuador's republican history during which the country attempted to make strides toward the establishment of a national identity.
The
R
amberg‐
B
äcklund Rearrangement
Authors: Paquette Leo A. 
Published: March 2007

Abstract
The halogen atoms of α‐halo sulfones, in contrast to halogen atoms α to other electron‐withdrawing functionalities, show marked resistance to substitution by external nucleophiles. Seemingly, polar, steric, and field effects combine to repel nucleophilic species. However, the same α‐sulfonyl halogen atoms are capable of facile intramolecular 1,3 elimination, leading to replacement of the sulfonyl group by a carboncarbon double bond with loss of halide and sulfite ions. This extrusion process, frequently referred to as the α‐halo sulfone or Ramberg‐Bäcklund rearrangement after its discoverers, has found broad utility in olefin synthesis. The reaction is generally applicable and easy to use.

Its earliest application dealt with the preparation of alkenes, the
cis
isomers of which predominated. Whereas such molecules may be more readily available by other methods, none of the alternative procedures offers the added option of specifically replacing the olefinic hydrogen atoms with deuterium by merely conducting the rearrangement in deuterated solvents. Moreover, because the α‐halo sulfones undergo this transformation in alkaline solution, further rearrangement of the initially formed alkenes is precluded. Therefore the SO
2
group in the starting sulfone is invariably replaced cleanly and unequivocally by the π bond.

The rearrangement is generally applicable to molecules containing the minimal structural requirements of a sulfonyl group, an α‐halogen atom, and at least one α′‐hydrogen atom, even in systems leading to small‐ring cycloalkenes. Di‐ and tri‐halo sulfones behave analogously. Conformational constraints, adverse hybridization characteristics, and excessive strain are known to deter the reaction. Inasmuch as these features arise only in special circumstances, they do not necessarily detract from its usefulness.
This chapter summarizes the more important advances in the understanding of α‐halo sulfone rearrangements, particular consideration being given to the nature of the intermediates, scope of the available synthetic alternatives, optimization of experimental conditions, and effect of structural features on reactivity. Closely related transformations are also discussed.
Heteroatom‐Facilitated Lithiations
Authors: Gschwend Heinz W. , Rodriguez Herman R. 
Published: March 2007

Abstract

Some 25 years have elapsed since the topic of metalation reactions was reviewed by Gilman and Morton. The intervening years have been notable for intensive explorations in this area, in part because many organolithium reagents are now commercially available. Specifically, research efforts have been characterized by the discovery of new functional groups that promote metalation, elaboration of novel heterocyclic and olefinic substrates as metalatable species, recognition of new types of lithiating agents, and the continuation of efforts to define accurately the mechanism of metalation. Accordingly, heteroatom‐facilitated lithiation has become recognized as an increasingly important tool, not only in the elaboration of carbocyclic aromatic and heteroaromatic systems, but also in synthetic aliphatic chemistry. A few recent reviews have covered the topic in a more limited or less specific sense. It is the purpose of this chapter to survey and classify the vast accumulation of heteroatom‐facilitated lithiations recorded since the first coverage in
Organic Reactions
.

As outlined by Gilman and Morton, the terms “metalation” in general and “lithiation” in particular denote any replacement of a hydrogen atom by metal or lithium. In this review, however, lithiation is defined as the exchange of a hydrogen atom attached to an
sp
2
‐hybridized carbon atom by lithium to form a covalent lithium‐carbon bond. More specifically, discussion is limited to those metalations that, through the influence of a heteroatom, are characterized by rate enhancement and regioselectivity. In fact, lithiation reactions of this type are noted for an extraordinarily high degree of regioselectivity, metalation generally occurring on the
sp
2
‐carbon atom closest to the heteroatom. Based on the relative position of the heteroatom, such lithiations are conveniently classified into two principal categories: alpha and beta (
ortho
) lithiations.

In
alpha
lithiations
the metalating agent deprotonates the
sp
2
‐carbon atom
alpha
to the heteroatom to form a carbonlithium bond. This
sp
2
‐carbon atom may be part of an olefinic or heteroaromatic π system.

In
beta
lithiations
the metalating agent is directed to deprotonate the
sp
2
‐carbon atom
beta
to the heteroatom‐containing substituent. The
sp
2
‐carbon atom can be part of an aromatic or an olefinic π system. It should be noted that the designation “
ortho
metalation” is used specifically for the beta metalation of carbocyclic aromatic systems.

This chapter surveys all systems in which alpha and beta lithiations have been observed, with the exception of ferrocenes.
Palladium‐Catalyzed Vinylation of Organic Halides
Authors: Heck Richard F. 
Published: March 2007

Abstract
The palladium‐catalyzed vinylation of organic halides provides a very convenient method for forming carboncarbon bonds at unsubstituted vinylic positions. Generally the reaction does not require anhydrous or anaerobic conditions although it is advisable to limit access of oxygen when arylphosphines are used as a component of the catalyst. The transformation is valuable because it cannot be carried out in a single step by any other known method (except in certain Meerwein reactions).

The organic halide employed is limited to aryl, heterocyclic, benzyl, or vinyl types, with bromides and iodides seen most often. Halides with an easily eliminated beta‐hydrogen atom (
i.e.
, alkyl derivatives) cannot be used since they form only olefins by elimination under the normal reaction conditions. The base needed may be a secondary or tertiary amine, sodium or potassium acetate, carbonate, or bicarbonate.

When nucleophilic secondary amines are used as coreactants with most vinylic halides, a variation occurs that often produces tertiary allylic amines as major products. The catalyst is commonly palladium acetate, although palladium chloride or preformed triarylphosphine palladium complexes, as well as palladium on charcoal, have been used. A reactant, product, or solvent may serve as the ligand in reactions involving organic iodides, but generally a triarylphosphine or a secondary amine is required when organic bromides are used. The reaction, which occurs between
ca.
50° and 160° proceeds homogeneously. Solvents such as acetonitrile, dimethylformamide, hexamethylphosphoramide, N‐methylpyrrolidinone, and methanol have been used, but are often not necessary. The procedure is applicable to a very wide range of reactants and yields are generally good to excellent.

Several variations of the reaction are known in which the organic halide is replaced by other reagents such as organometallics, diazonium salts, or aromatic hydrocarbons. These reactions are not discussed in detail, but are only briefly compared with the halide reaction. Other related reactions such as the palladium‐catalyzed replacement of allylic substituents with carbanionic reagents, the palladium‐promoted nucleophilic substitutions at olefinic carbons, and the numerous palladium‐catalyzed coupling reactions of halides and organometallics are also beyond the scope of this review. The palladium‐catalyzed vinylic substitution reaction has not yet received much attention from organic chemists, but its broad scope and simplicity demonstrate that it is a useful method for the synthesis of a variety of olefinic compounds.
Olefin Synthesis by Deoxygenation of Vicinal Diols
Authors: Block Eric 
Published: March 2007

AbstractSince the discovery in 1963 that 1,3‐dioxolane‐2‐thiones (cyclic thionocarbonates) undergo stereospecific fragmentation to olefins on heating with trivalent phosphorus compounds (the Corey–Winter reaction), a variety of approaches have been developed for the regio‐ and stereospecific (or stereo‐selective) deoxygenation of vicinal diols based onsynelimination from cyclic derivatives. These methods have been particularly useful in synthesizing substrates with delicate structural features such as strained and twisted olefins, unsaturated carbohydrates, macrocyclic lactones, lipids, and polyenes, as well as in establishing the stereochemistry of diol functions in natural products.This chapter deals primarily with deoxygenation of vicinal diols via cyclic species with X = C, P, Ti, W, or S (suitably functionalized). Brief coverage is given to deoxygenation processes that do not involve cyclic intermediates, whereas routes proceeding via oxiranes orvic‐dihalides as separately isolated intermediates are excluded from consideration. The stereochemical equilibration of vicinal diols and the conversion of vicinal hydroxy thiols and dithiols to olefins are also covered in this chapter. Brief reviews have appeared in the literature of the Corey–Winter reaction and of the general topic of deoxygenation of vicinal diols.
Catalytic Enantioselective Aldol Addition Reactions
Authors: Carreira Erick M. , Fettes Alec , MartI Christiane 
Published: March 2007

Abstract
The aldol addition reaction has become a strategically important, reliable transformation that is widely employed in the asymmetric synthesis of complex molecules. It can be counted on not only to provide access to polyketide fragments with their characteristic 1,3‐oxygenation pattern, but also to numerous other classes of compounds, such as oxo‐heterocycles, alpha and beta‐amino acids, and nucleosides.
Two general approaches have emerged for aldol reaction: (1) diastereoselective additions, wherein stoichiometric quantities of a covalently bound, chiral controlling element shepherds the stereochemical course of the reaction and, alternatively, (2) enantioselective methods wherein a chiral catalyst functions as the stereochemical controlling element. Diastereoselective methods remain dominant. Enantioselective methods are new on the scene. However, explosive development has led to complex molecule assembly via catalytic asymmetric aldol transformations. Such reactions are described here.
Molecular pathogenesis of seipin/BSCL2‐related motor neuron diseases
Authors: Ito Daisuke , Suzuki Norihiro 
Published: March 2007

AbstractObjectiveHeterozygous mutations in the Seipin/BSCL2 gene have recently been identified in two autosomal dominant motor neuron diseases, distal hereditary motor neuropathy type V and Silver's syndrome. Seipin protein is reportedly a transmembrane protein localized in the endoplasmic reticulum (ER). N88S and S90L mutations of this protein disrupt its glycosylation, resulting in its aggregation, but the mechanism of neurodegeneration remains unclear. To clarify the molecular pathogenesis of seipin‐related motor neuron diseases, we expressed wild‐type and mutant seipin proteins in neuronal and nonneuronal cells.Methods and ResultsCoexpression of human seipin and ubiquitin showed that seipin is polyubiquitinated and its ubiquitination is enhanced by mutation. Treatment of cells with a proteasome inhibitor increased the amounts of mutant seipin in the cells, suggesting that they are degraded through the ER‐associated degradation pathway. Immunoprecipitation studies showed that mutant seipin stably binds to the ER chaperone calnexin, indicating accumulation of unfolded mutant seipin in the ER. Furthermore, expression of mutant seipin increased the level of ER stress–mediated molecules and induced apoptosis in cultured cells.InterpretationThese findings demonstrate that seipin/BSCL2‐related motor neuron diseases are novel conformational diseases, and we suspect that they are tightly associated with ER stress–mediated cell death. Ann Neurol 2007;61:237–250
Mesenchymal stem cells effectively modulate pathogenic immune response in experimental autoimmune encephalomyelitis
Authors: Gerdoni Ezio , Gallo Barbara , Casazza Simona , Musio Silvia , Bonanni Ivan , Pedemonte Enrico , Mantegazza Renato , Frassoni Francesco , Mancardi Gianluigi , Pedotti Rosetta , Uccelli Antonio 
Published: March 2007

AbstractObjectiveTo evaluate the ability of mesenchymal stem cells (MSCs), a subset of adult stem cells from bone marrow, to cure experimental autoimmune encephalomyelitis.MethodsThe outcome of the injection of MSCs, in mice immunized with the peptide 139–151 of the proteolipid protein (PLP), was studied analyzing clinical and histological scores of treated mice. The fate of MSCs labeled with the green fluorescent protein was tracked in vivo by a photon emission imaging system and postmortem by immunofluorescence. The modulation of the immune response against PLP was studied through the analysis of in vivo T‐ and B‐cell responses and by the adoptive transfer of MSC‐treated encephalitogenic cells.ResultsMSC‐treated mice showed a significantly milder disease and fewer relapses compared with control mice, with decreased number of inflammatory infiltrates, reduced demyelination, and axonal loss. In contrast, no evidence of green fluorescent protein–labeled neural cells was detected inside the brain parenchyma, thus not supporting the hypothesis of MSCs transdifferentiation. In vivo, PLP‐specific T‐cell response and antibody titers were significantly lower in MSC‐treated mice. When adoptively transferred, encephalitogenic T cells activated against PLP139–151 in the presence of MSCs induced a milder disease compared with that induced by untreated encephalitogenic T cells. These cells showed decreased production of interferon‐γ and tumor necrosis factor‐α and did not proliferate on antigen recall, and thus were considered anergic.InterpretationOverall, these findings suggest that the beneficial effect of MSCs in experimental autoimmune encephalomyelitis is mainly the result of an interference with the pathogenic autoimmune response. Ann Neurol 2007;61:219–227
Correction
Authors: Meyer zu Horste Gerd , Prukop Thomas , Liebetanz David , Mobius Wiebke , Nave Klaus‐Armin , Sereda Michael W. 
Published: March 2007

AbstractIn the original published article, the first sentence of the Intrepretation section in the article's abstract was incorrectly printed. The sentence should read:

Intrepretation:Progesterone‐antagonist long‐term therapy reduces Pmp22 overexpression to a degree at which the axonal support function of Schwann cells is better maintained than myelination.
Optimization of fed‐batch parameters and harvest time of CHO cell cultures for a glycosylated product with multiple mechanisms of inactivation
Authors: Senger Ryan S. , Karim M. Nazmul 
Published: March 2007

AbstractOptimization of fed‐batch feeding parameters was explored for a system with multiple mechanisms of product inactivation. In particular, two separate mechanisms of inactivation were identified for the recombinant tissue‐type activator (r‐tPA) protein. Dynamic inactivation models were written to describe particular r‐tPA glycoform inactivation in the presence and absence of free‐glucose. A glucose‐independent inactivation mechanism was identified, and inactivation rate constants were found dependent upon the presence of glycosylation of r‐tPA at N184. Inactivation rate constants of the glucose‐dependent mechanism were not affected by glycosylation at N184. Fed‐batch optimization was performed for r‐tPA production by CHO cell culture in a stirred‐tank reactor with glucose, glutamine and asparagine feed. Feeding profiles in which culture supernatant concentrations of free‐glucose and amino acids (combined glutamine and asparagine) were used as control variables, were evaluated for a wide variety of set points. Simulation results for a controlled feeding strategy yielded an optimum at set points of 1.51 g L−1 glucose and 1.18 g L−1 of amino acids. Optimization was also performed in absence of metabolite control using fixed feed‐flow rates initiate during the exponential growth phase. Fixed feed‐flow results displayed a family of optimum solutions along a mass flow rate ratio of 3.15 of glucose to amino acids. Comparison of the two feeding strategies showed a slight advantage of rapid feeding at a fixed flow rate as opposed to metabolite control for a product with multiple mechanisms of inactivation. Biotechnol. Bioeng. 2007;98: 378–390. © 2007 Wiley Periodicals, Inc.
Unusual CD couplet pattern observed for the π*←n transition of enantiopure (Z)‐8‐methoxy‐4‐cyclooctenone: An experimental and theoretical study by electronic and vibrational circular dichroism spectroscopy and density functional theory calculation
Authors: Tanaka Takeyuki , Oelgemöller Michael , Fukui Keijiro , Aoki Fumiko , Mori Tadashi , Ohno Takashi , Inoue Yoshihisa 
Published: March 2007

AbstractUltraviolet absorption (UV) and electronic circular dichroism (ECD) spectra of enantiopure (Z)‐8‐methoxy‐4‐cyclooctenone (MCO) were measured in hexane to give a normal single UV absorption band at 298 nm, which is assigned to the carbonyl's π*←n transition. Unexpectedly, the ECD spectrum exhibited an apparent couplet pattern with vibrational fine structures. Obviously, the conventional CD exciton coupling mechanism cannot be applied to this bisignate CD signal observed for single‐chromophoric MCO. Variable temperature‐ECD and vibrational circular dichroism (VCD) spectral measurements, simultaneous UV and ECD spectral band resolution, and density functional theory (DFT) calculations of energy and structure revealed that this apparent CD couplet originates from a rather complicated spectral overlap of more than three conformers of MCO, two of which exhibit mirror‐imaged ECD spectra at appreciably deviated wavelengths. In the simultaneous band‐resolution analysis, the observed UV and ECD spectra were best fitted to four overlapping bands. Two major conformers were identified by comparing the experimental IR and VCD spectra with the simulated ones, and the other two by comparing the observed UV and ECD spectra with the theoretical ones obtained by time‐dependent DFT calculations. It was shown that the combined use of experimental ECD and VCD spectra and theoretical DFT calculations can give a reasonable interpretation for the Cotton effects of the conformationally flexible molecule MCO. Chirality, 2007. © 2007 Wiley‐Liss, Inc.
Hemodynamic changes during cardiac resynchronization therapy
Authors: Nägele H. , Azizi M. , Castel M. A. 
Published: March 2007

AbstractCardiac resynchronization therapy (CRT) is a new method for the correction of inter‐ and/or intraventricular conduction delays of patients with heart failure. The long‐term impact of CRT on central hemodynamics is not fully characterized. We performed complete right heart catheterization studies in 31 patients receiving a CRT device pre and 6 months after implantation. Most of the patients improved in their NYHA stage, their LVEF, and in parallel showed reduced right atrial (RA) pulmonary artery (PA) and pulmonary capillary wedge (PCW) pressures and pulmonary vascular resistance both at rest and at 25 watts. In addition, we found a reduction in heart rate accompanied by an increased mean arterial pressure both at rest and at 25 watts. Accordingly, brain natriuretic peptide levels (BNP) were lowered. It was concluded that, besides other well‐known effects on ventricular coordination, central hemodynamics after 6 months were improved during CRT. Copyright © 2007 Wiley Periodicals, Inc.
Combined use of endothelial function assessed by brachial ultrasound and high‐sensitive C‐reactive protein in predicting cardiovascular events
Authors: Huang Po‐Hsun , Chen Jaw‐Wen , Lu Tse‐Min , Yu‐An Ding Philip , Lin Shing‐Jong 
Published: March 2007

AbstractBackgroundEndothelial function plays a key role in determining the clinical manifestations of atherosclerotic lesions. Elevated high‐sensitive C‐reactive protein (hsCRP) relates to long‐term prognosis of cardiovascular disease.HypothesisWe test the hypothesis that combined use of endothelial function and hsCRP could increase predictive value of future cardiovascular events.Methods and Results205 patients were followed up for a median period of 24 months. Endothelial function was assessed using brachial ultrasound to measure endothelium‐dependent flow‐mediated vasodilation (FMD). Cox regression analyses were conducted for the 205 subjects, with cardiovascular events being defined as myocardial infarction, hospitalization due to congestive heart failure, percutaneous coronary intervention, coronary artery bypass grafting, and ischemic stroke. Twenty nine (14%) developed cardiovascular events. Both FMD and hsCRP were significantly predictive of cardiovascular events (relative risk for patients with FMD < 3% as compared to those with FMD > 6%, 4.65, 95% confidence interval (CI): 1.30‐16.66, p = 0.018; relative risk for the highest as compared with the lowest tertile of hsCRP level, 3.59, 95% CI: 1.32‐9.74, p = 0.012, respectively). Further risk analysis was performed among four groups classified by FMD (FMD ≥ 6% or < 6%) and half percentile of hsCRP (hsCRP ≥ 1 or < 1 mg/dL). Relative risks for the FMD < 6%/hsCRP ≥ 1 mg/dL group compared to FMD ≥ 6%/hsCRP < 1 mg/dL group increased markedly to 12.598 (95% CI: 1.69 to 94.14, p = 0.014) for cardiovascular events.ConclusionsPatients with suspected coronary artery disease may benefit from risk stratification based on both endothelium‐dependent FMD and hsCRP, since combined these two factors contribute significantly toward the incidence of cardiovascular events. Copyright © 2007 Wiley Periodicals, Inc.
Chronic pretreatment of ACEI reduces no‐reflow in patients with acute myocardial infarction treated with primary angioplasty
Authors: Zhao Jing‐Lin , Yang Yue‐Jin , Zhang Yuan‐Hui , Pei Wei‐Dong , Sun Yu‐Hua, , Chen Ji‐Lin , Gao Run‐Lin 
Published: March 2007

AbstractBackgroundIn animal models, pretreatment with angiotensin‐converting enzyme inhibitor (ACEI) can reduce no‐reflow. In the present study, we investigated whether pretreatment with ACEI may prevent no‐reflow in patients who underwent primary coronary intervention for AMI.Method and ResultsA total of 259 consecutive patients who underwent primary angioplasty for a first AMI were studied. No‐reflow was defined as a TIMI flow grade < 3. The no‐reflow phenomenon was found in 33 of 259 patients. There were no significant differences in clinical characteristics between the patients with and without ACEI pretreatment. However, the 47 patients receiving chronic ACEI treatment before admission had lower incidence of the no‐reflow than those without it (4.2 and 14.6%, p < 0.05). Multivariable logistic regression analysis revealed that absence of ACEI pretreatment was a significant predictor of the no‐reflow along with absence of preinfarction angina, complete occlusion of the culprit lesion, high‐burden thrombus, ejection fraction on admission, number of Q‐waves, absence of statin pretreatment, and anterior AMI.ConclusionPretreatment with ACEI could preserve the microvascular integrity after acute myocardial infarction in humans. Copyright © 2007 Wiley Periodicals, Inc.